vol. 45,no.5 la physique au canada septembre 1989 … · symmetries in physic — ths e unitar...

La Physique au Canada Vol. 45, No. 5

September/ septembre 1989

V r ,

%

\ ' * A j V r

1

Corporate Members/Membres Corporatifs Canadian Association of Physicists/Association canadienne des physiciens

The Corporate Members of the Canadian Association of Les Membres corporatifs de l'Association Canadienne des Physicists are a group of corporations, laboratories and Physiciens sont un groupe de corporations, laboratoires ou institutions who through their membership support the institutions qui supportent f inancièrement les activités éduc-educational activities of the Association. atives de l'Association.

The entire proceeds of corporate membership contr ibu- Les revenus de leurs contr ibut ions déductibles aux fins t ions are paid into the CAP Educational Trust Fund and d ' impôt sont entièrement versés au Fonds Educatif de l'ACP. are tax deductible.

ACCUREX TECHNOLOGY INCORPORATED ALCAN INTERNATIONAL LTD. ALLAN CRAWFORD ASSOCIATES LTD. APTEC ENGINEERING LIMITED ATLANTIS AEROSPACE CORPORATION ATMOSPHERIC ENVIRONMENT SERVICE ATOMIC ENERGY OF CANADA LIMITED BELL-NORTHERN RESEARCH LTD. CAE ELECTRONICS LTD. CANADIAN INDUSTRIAL INNOVATION CENTRE/WATERLOO COMINCO LTD. ELECTRONIC MATERIALS CTF SYSTEMS INC. EALING SCIENTIFIC LIMITED EDWARDS HIGH VACUUM (CANADA) LIMITED EG & G INSTRUMENTS HYDRO-QUÉBEC LEIGH INSTRUMENTS LIMITED LINEAR TECHNOLOGY INC. LUMONICS INC. MITEL CORPORATION MOLI ENERGY LIMITED MPB TECHNOLOGIES INC. NATIONAL OPTICS INSTITUTE ONTARIO HYDRO OPTECH INCORPORATED OPTO ELECTRONICS INC. POLYSAR LTD. QUEEN'S UNIVERSITY RAYONICS INC. RCA INC. SOUTHERN ALBERTA INSTITUTE OF TECHNOLOGY SPAR AEROSPACE LIMITED SRP CONTROL SYSTEMS LTD. TASMAN SCIENTIFIC INC. TECHNICAL MARKETING ASSOCIATES LIMITED TRIUMF VG INSTRUMENTS CANADA INC. UNIVERSITY OF WATERLOO XEROX RESEARCH CENTRE OF CANADA

The Canadian Association of Physicists cordially invites L'Association Canadienne des Physiciens invi le cordialement interested corporat ions and institutions to make applica- corporations et institutions à faire partie des Membres Cor-t ion for Corporate membership and wi l l welcome the poratifs. Renseignements auprès du Secrétaire Exécutif, inquiries addressed to the Executive Secretary.

CANADIAN ASSOCIATION OF PHYSICISTS/ASSOCIATION CANADIENNE DES PHYSICIENS 151 Slater, Suite 903

Ottawa, Ontario K1P 5H3

52 Physics in Canada January 1989

The Bulletin of The Canadian Association of Physicists Bulletin de l'Association canadienne des physiciens

EDITORIAL B O A R D / C O M I T E DE R É D A C T I O N

Editor/Rédacteur en chef G. Doll ing Chalk River Nuclear Laboratories, Chalk River, Ontario K0| 1)0 (613) 584-331 1-401 1

Associate Editor/Rédacteur Associé M.L. Jento Managing/Administration

Book Review Editor/Rédacteur à la critiques des livres G.R. Hébert Dept. of Physics, York University 4700 Keele St. North York, On I. M3J 1 P3 (416) 736-2100 X 3837

I.C. Cook Division of Physics, National Research Council, Montreal Rd„ Ottawa, Ontario Kl A 0R6 (613) 993-9407

Béla |oos University of Ottawa, Ottawa, Ont. K1N 6N5 (613) 564-3460

John A. Nilson 1778 Gilbert Ottawa, Ont. K2C 1A4 (613) 225-5426

R.H. Packwood Physical Metallurgy Research Laboratories E-M-R 568 Booth St. Ottawa, Ont. (613) 992-2288

René Roy Département de physique Université Laval Cité Universitaire Québec (Québec) G1 K 7P4 (418) 656-2655

ANNUAL SUBSCRITPION RATE/ABON-NEMENT PAR AN $30.00 ADVERTISING, SUBSCRIPTIONS, CHANGE OF ADDRESS PUBLICITÉ, ABONNEMENT, CHANGEMENT D'ADRESSE :

Canadian Association of Physicists Association canadienne des physiciens Suite 903, Slater Street Ottawa, Ontar io K1P 5H3 Phone: (613) 237-3392 BITNET: WCSCAP @ Carleton FAX: (613) 238-1677

Physics in Canada Vol . 45, No . 5

La Physique au Canada September /

septembre 1989

Rock M a g n e t i c R e c o r d i n g s by W y n W i l l i a m s a n d D a v i d ). D u n l o p

T h e Sc ien t i f i c P r o g r a m of t h e T o k a m a k d e V a r e n n e s by C.C. D a u g h n e y

S y m m e t r i e s in Physics — t h e U n i t a r y C r o u p A p p r o a c h by M . Sch les inger a n d R.D. Kent

CAP L u m o n i c s A w a r d s

O s c i l l a t o r S tud ies o f Flux D y n a m i c s in C e r a m i c H i g h T e m p e r a t u r e S u p e r c o n d u c t o r s

by D a v i d J. Baar

Te t rac r i t i ca l B e h a v i o u r o f C s M n B r j by T.E. M a s o n , M.F. Co l l i n s , B.D. G a u l i n a n d J.Z. Larese

Analys is o f S p u t t e r i n g F r o m a T iC C o a t e d Test L im i te r in t h e T o k a m a k d e V a r e n n e s

by D.A. Po i r ie r , B.L. Stansf ie ld , W . W . Z u z a k , L. Pe l le t ie r , R.C. Sa in t -Jacques a n d t h e Tokamak de Varennes T e a m

Page N o .

137

141

146

151

153

154

Departments/ Rubriques C o r p o r a t e M e m b e r s / M e m b r e s c o r p o r a t i f s

Le t te rs /Le t t res

CAP A f fa i r s /A f fa i res d e I 'ACP

N e w s / N o u v e l l e s

C a n a d i a n Phys ic is ts /Phys ic iens c a n a d i e n s

Books Rece i ved /L i v res reçus

B o o k R e v i e w s / C r i t i q u e s des l ivres

IFC

136

155

165

166

169

170

Front Cover: T h e t h r e e - d i m e n s i o n a l v a r i a t i o n of m a g n e t i z a t i o n w i t h i n a 0 .2 / im c u b e o f m a g n e t i t e . In th is s o l u t i o n t h e m a g n e t i c s t r u c t u r e is u n d e r g o i n g a t r a n s f o r m a t i o n d u e to an ex te rna l l y a p p l i e d f ie ld .

Typesetting, Layout and Print ng : T r i - G r a p h ic P r i n t i n g ( O t t a w a ) L i m i t e d

Advertising Rates Effective January 1988

Single Issue Jan. March July Sept.

Nov. Congress Issue

(May)

One-year-Contract (6 issues)

Full Page Half Page

$550.00 385.00

$600.00 440.00

$440.00 330.00

Quarter Page 220.00 245.00 190.00 Fourth Cover 660.00 725.00 560.00 Second & Third Cover 600.00 660.00 510.00

Colour, $200.00 each addit ional colour; Bleed $120.00 Typesetting and art t ime extra

Deadline for copy — 15th of previous month Published — |an., March, May (Congress), July, Sept., Nov.

©Canadian Association of Physicists/Association canadienne des physiciens 1989. All rights reserved. Second Class Mail Registration Number: 5415 ISSN 0031-9147.

Letters/Lettres There is a general assumption by the publ ic that Canadian "Space Science" (other than astronomy) is recent. However, Canadian work in the field goes back several generations.

The earliest paper to come to our attention is by J.C. McLennan and G.M. Shrum on the 5577A Auroral line (Proc. Roy. Soc. London, A106, 138 (1924)). We should be pleased to learn of any earlier publications in the field report ing work done in Canada.

Yours sincerely,

Larkin Kerwin, c.c. President, Canadian Space Agency

Rock Magnetic Recordings

by Wyn Williams* and David /. Dunlop Geophysics Laboratory Department of Physics University of Toronto

Geomagnetism

Nearly all of the rocks that form the Earth's crust are magnetic to some extent, due to small traces of magnetic minerals w i th in them. The most c o m m o n such mineral is the i ron oxide magnetite, wh ich is abundant in lodestone and wh ich the Chinese used over 4000 years ago as a compass.

Modern research into the magnetic propert ies of rocks began w i th Delesse and Mel lon i in the mid n ineteenth century. They discovered that most of the magnetism of igneous rocks was acquired as they fo rmed and coo led in the Earth's magnetic f ield. Later Folgerhaiter demonstrated that the magnetic moment that was t rapped in the rocks pointed in the d i rect ion of the ambient magnetic f ield at the t ime the rocks formed.

The use of rocks to determine the Earth s ancient history can be traced back to David (1904) and Brunhes (1906) w h o not iced that the d i rect ion of the magnetizat ion in some ancient lavas was almost exactly opposi te the present f ield di rect ion. They speculated that the Earth's f ield had reversed at some t ime in the past. Such f ield reversals have since been conf i rmed by many magnetic measurements f rom all over the Earth's surface. As the abil i ty to measure the magnetism recorded by rocks increased, and the understanding of magnetic phenomena grew, it became possible to measure the d i rect ion of a rock's magnetic moment to w i th in a few degrees. Assuming that the Earth's magnetic pole (either normal or reversed) is on average coinc ident w i th one of the geographic poles, then one cou ld test the theory original ly put forward by Wegener in 1920, that the cont inents are dr i f t ing on the Earth's surface.

Not only does the rock record the ancient f ield di rect ion, but it also records the ancient f ield intensity, and this too has been explo i ted to unveil the Earth's geological history.

The foundat ions of this vast area of research in paleo-magnetism are laid on the abil ity of c o m m o n minerals to accurately record the changes in the Earth's magnetic field. As paleo- and rock-magnetists' abil i ty to measure the mag-netism of rocks increases, it becomes more and more im-portant to proper ly understand the mechanism by wh ich ancient fields are recorded. Are the recordings stable enough to last mi l l ions of years? How can we detect wh ich grains in the rock are good recorders and wh ich are bad? Have there been physical or chemical changes to the grain since it was fo rmed that might alter its or iginal magnetization? The answers to these questions have been sought for over fifty years.

Magnetic Stability

Most magnetic materials fo rm domain structures. Magnetic domains are simply regions of un i form magnetizat ion (i.e. regions in wh ich the magnetizat ion d i rect ion does not vary). There may be many domains w i th in a single magnetic crystal, and it is only when a large fract ion of the domains point in the same d i rect ion that the sample's magnetic moment becomes measurable. The stability of the sample's magnetism is therefore dependent on the stability of its domain structure. Grains of magnetic minerals, such as magnetite, can be

* Present address, Depar tmen t of Geophysics, Univers i ty of Edin-burgh, Mayf ie ld Road, Ed inburgh EH9 3JZ, UK.

classified into three groups wh ich describe their general magnetic properties. The smallest grains (less than about 0.1/1im for cubic grains of magnetite) contain only one domain. These single-domain (SD) grains carry large magnetic mo-ments. Large grains (larger than about 20 yum for magnetite) that contain many domains (i.e. mul t idomain or MD) generally have small magnetic moments. Finally grains wh ich contain only a few domains are often called pseudo-single-domain (PSD) grains. They exhibit many of the propert ies of M D grains, but still carry large magnetic moments.

The physics of single-domain grains is wel l understood, and can be formulated analytically (Néel, 1949). Rocks conta in ing predominant ly s ingle-domain grains acquire very large and stable magnetic moments by cool ing in a magnetic f ield f rom a temperature near or above the mineral's Curie temperature (Tc), wh ich for magnetite is 580°C, wel l below the mel t ing temperature of most rocks (about 1000°C). At the Curie temperature, the sample's magnetic energy falls to zero. Its magnetic moment quick ly rotates to align wi th the ambient field, and remains in this d i rect ion as the sample cools. At room temperature the magnetizat ion is locked, so that the d i rect ion of the magnetic vector in the rock wi l l not change even if the ambient f ield does. Single-domain grains are very stable at room temperature, having relaxation times, r , of the order of mil l ions of years, as def ined by

r-> = C exp(-EJkT)

Here Em is the energy barrier to be crossed in transit ions between domains of dif ferent or ientat ion, k is Boltzmann's constant, T is the absolute temperature, and C is the rate factor wh ich has a value of about 1 0 V 1 (£„, is of the order of 100 kTH, T0 being room temperature)

Thus if they are not reheated or chemical ly altered, the single-domain magnetite grains are capable of ho ld ing records of pr imary magnetic fields of even the oldest rocks on Earth.

A l though single-domain behaviour is wel l understood, it is likely that a sample wi l l also contain grains wh ich are PSD or MD, so if we are to complete ly resolve the magnetic vector recorded in the rock we must also be able to predict the behaviour of these larger grains. The most recent attempts at model l ing magnetic grains (Schabes & Bertram 1988, Wil l iams & Dun lop 1989) have concentrated on PSD grains since, in general, these are responsible for a larger fract ion of the sample's magnetism than the M D grains.

Micromagnetism

The techn ique used to model the magnetic domain structure is called micromagnet ism. It takes a semi-classical approach in that it uses the basic magnetostatic and electrostatic forces that can only be fully understood on the quantum mechanical level, but applies these forces to a model in wh ich the magnetizat ion is represented as a cont inuous vector. Initially these studies were analytic (Bloch 1932, Landau & Lifshitz 1935), but the models were simplistic and involved constrain-ing the magnetizat ion to one dimensional variations wh ich cou ld be described by simple analytic funct ions.

Computers in the 1960's prov ided the tool w i th wh ich to bui ld less constrained models. A l though init ial ly still one-

La Physique au Canada septembre 1989 137

dimensional (Brown and LaBonte 1965) the variation of the magnetization was not constrained to blocks having pre-defined direction's of magnetization (Amar, 1957) or to fol low analytic functions. In the late 1960's, two-dimensional models were formulated (LaBonte, 1969) and in the last year full three-dimensional solutions have been achieved, with the aid of powerful supercomputers.

All micromagnetic models are similar in that they calculate the effects of competing forces on the electron spins which generate the samples' magnetic moment. In computational models the grain is divided up into many elements, and the magnetization within each element is averaged and repres-ented as a magnetic dipole placed at the centre of the element. The models described here are those of Williams and Dunlop (1989). There are five important interactions which have to be considered.

1) The exchange energy.

£ f = -2 2 2 2 h ^ • s, x y z

where JE is the exchange integral, and Sj and Sj are the spin vectors. This is a consequence of Pauli's exclusion principle for electrons in overlapping orbitals of neighbouring cations. It is a short-range force, whose effect is to align neighbouring spins parallel or antiparallel to each other.

2) The magnetocrystalline anisotropy energy.

= X X X («MW + a22a32 + a3W) + K2a,2ot2W) x y z

where K1r K2 are the anisotropy constants and a :,a2,a3, are the direction cosines of the magnetic vector (tv

This is due to the interaction of the electron spins with the orbital magnetic moments of the atoms, and has the effect of aligning the magnetization along certain 'easy' crystallo-graphy axes.

3) The magnetoelastic energy.

Es • ~ X X cos2 <t> 2 x y z

where A is the magnetostrictive constant, a is the magne-toelastic stress and 4> is the angle between the stress and magnetization direction.

This is the magnetic energy due to deformation of the crystal lattice. In magnetite it is an order of magnitude smaller than the anisotropy energy, and so is not included in the numerical calculations.

4) The external field magnetostatic energy.

This is due to the magnetostatic interaction of an externally applied field with the sample's magnetization.

5) The magnetostatic demagnetizing energy.

E d = -—X X X mi ' Hi 2 x y z

where Hj is the magnetic field at the location of mi due to all the other dipoles.

This is the Coulomb-l ike non-linear interaction between the dipoles. The force is long-ranged; every dipole interacts with every other dipole in the sample. The overall effect of this force is to align the spins to be anti-parallel to each other.

As a generalization, the exchange forces wil l dominate in the smaller grains, and the demagnetizing forces in the larger. The grain may reduce its demagnetizing energy, at the expense of the increased exchange energy, by forming domains whose magnetizations point in different (usually antiparallel) directions.

Because of the long-range and non-linear nature of the demagnetizing interactions, powerful computers are required to solve the full three-dimensional micromagnetic models.

The numerical procedure is to sum the total magnetic energies arising from the interactions listed above, and the minimize the energy to find stable magnetic structures. In any one iteration of the minimization manv millions of interactions are required for even a modest grid resolution (eg 12 x 12 x 12). When a minimum energy structure is obtained, it is virtually impossible to prove that there is no other existing structure with a lower energy. However it is possible to identify some surface magnetic structures ex-perimentally using magnetic colloids (similar to that of map-ping field lines on a magnet by using iron filings), and these experiments demonstrate that a grain may have many different stable magnetic structures (Halgedahl & Fuller, 1983). These then correspond to the local min imum energy structures of the numerical models. Various types of structures that have been predicted by the three-dimensional modell ing are shown in figure 1. The mag-netostatic demagnetizing energies of these solutions are two to three times lower in absolute value than those of cor-responding solutions with only one- and two-dimensional variations, demonstrating that the variation of the magne-tization in a small grain is fully three-dimensional and that the structures predicted by one- and two-dimensional models were indeed overly constrained. In order to realise the significance of the new results, it is important to understand the concepts that have been devel-oped over the last 50 years with other micromagnetic so-lutions. Whi le we wil l demonstrate that many of these con-cepts must be modified to accommodate the results of the three-dimensional models, much progress has been made with the simpler models, and their simplicity still allows investigations of certain aspects of domain theory, such as stability to thermal fluctuations, which cannot yet be sim-ulated in full three dimensions. Some of the major ideas of the early models may be summarized as follows.

1) Domains are lamellar in nature.

2) Domain walls (i.e. transition regions between domains) occupy a significant fraction of the grain volume.

3) Rotations between domains are usually via Bloch walls; i.e. spins rotate parallel to the plane of the walls and normal to the crystal surfaces intersecting the walls.

4) The magnetic structures change by adding or subtracting one domain.

5) The body domains extend to the surface of the grain, so that mapping the surface fields uniquely defines the interior domain structure.

6) The magnetocrystalline anisotropy of the grain strongly influences both domain structure and coercivity (the field that must be applied to alter the domain structure). Figure 1 shows some of the results of three-dimensional micromagnetic modell ing (Williams & Dunlop 1989). From these figures it can be seen that several of the ideas of earlier models are not true. First, the domains are not lamellar. In the cubic grains modelled, separate domains ;orm in regions of high demagnetizing fields, such as at the cube corners and edges, and steadily grow to form larger and larger fractions of the grain volume as the grain size, for instance, increases.

The domain walls are not planar and wil l usually curve to become parallel to the crystal surfaces, such as in the corner domains of figure 1b, as they approach the top and bottom grain surfaces. This means that the surface magnetization and field patterns will not necessarily indicate the domain struc-ture in the body of the grain. Also in figure 1b, although distinct domain walls can be identified (the regions where the spins have intermediate directions between up and down) these transition regions are narrow and form only a small fraction of the grain volume.

138 Physics in Canada September 1989

Fig. 1. Various types of magnetic structures in 0.2^m cubes of magnetite, (a) A single-domain structure, showing deflection of the magnetization at the cube corners, (b) A 5-domain structure, with antiparallel domains at the cube edges, (c) A two-domain structure, with large closure domains, (d) A 5-domain structure dominated by internal flux loops.


Comparison of figures 1a and 1b indicates how the domain state of a grain might evolve. In grains of increasingly larger sizes, the demagnetizing forces wi l l become bigger. These wi l l be strongest at the cube corners, and it is in these regions that the magnetization begins to rotate (figure 1a). As the demagnetizing forces increase, these deflections of the mag-netization increase further, and eventually the rotations of the magentizations at opposite corners along a cube edge wi l l jo in to form edge domains (the regions where the spins are point ing downwards in f igure 1b). Thus the domain state wi l l transform f rom a one-domain to a f ive-domain structure, there being a domain at the grain centre which points in the +Z direct ion, and four domains which point in the - Z direct ion at the cube edges. When viewed on one of the side surfaces, howerver, it wou ld appear as a three domain grain since the central body domain has arms which extend to the surface (the regions of upward point ing spins on the side surfaces of f igure 1b).

In all solutions the magnetocrystall ine anisotropy easy axes are the eight cube diagonals, but it can be seen that this has not caused the domain structure to deform and prefer-entially align along the 'easy' magnetization axes. In fact for magnetite, the direct ion of the anisotropy axis may be changed wi th very little change in the domain structure.

These new results thus differ radically f rom the tradit ional concepts of domain structure in PSD grains. However, even these three-dimensional solutions have not al lowed for some important factors that wi l l inf luence domain structure, such as irregular grain shapes and grain imperfections. The use-fulness of the models must be judged by the accuracy to which it can predict experimental results. Preliminary inves-tigations show that an equipart i t ion of al lowed domain states in grains ranging f rom 0.05^m to 0.5/um fits the experimental data for the grain size dependence of saturated magnetic moments in bulk magnetic samples, that is in samples con-taining many grains. However, more rigorous testing needs to be carried out by observation of domain patterns on individual submicron grains.

These calculations are being cont inued at the University of Toronto, to generate the response of the magnetic structures to changes in external fields and temperature and to inves-tigate the energy barriers between states. The results wi l l be compared to the experimental data being gathered at Toronto and other universities in Canada, the U.S.A. and Europe.

Acknowledgement

This work was supported by an NSERC grant to D.J.D., and also an NSERC supercomputer access grant. We are also grateful to Dr. Bregman of the Ontario Centre for Large Scale Computat ion for her help, and James Rowell for the pro-duct ion of the colour graphics.

References

1. Amar H., On the width and energy of domain walls in small mult i -domain particles /. Appl. Phys., 28, 732-733, 1957.

2. Bloch F., Zur Theorie des Austauschproblems und der Remanenzerscheinung der Ferromagnetika, Z. Phys., 74, 295-335, 1932.

3. Brown W. F. & LaBonte A. E., Structure and energy of one-dimensional walls in ferromagnetic thin films, I. Appl. Phys., 36, 1380-1386, 1965.

4. Brunhes B., Recherches sur la direct ion d'aimantation des roches volcaniques, /. Phys, 5, 705, 1906.

5. David P., Sur la stabilité de la direct ion d'aimantation dans quelques roches volcaniques, C. R. Acad. Sci. Paris, 138, 41, 1904.

6. Delesse, A., Sur le magnétisme polaire dans les minéraux et dans les roches, Ann. Chim. Physique, 25, 194, 1849.

7. Folgerhaiter G., Sur les variations séculaires de l ' inclinai-son magnétique dans l'antique, /. Phys, 8, .5, 1899.

8. Halgedhal S. & Fuller M., The dependence of magnetic domain structure upon magnetization state wi th emphasis upon nucleation as a mechanism for pseudo single domain behaviour, / Geophys. Res., 88, 6505-6522, 1983.

9. LaBonte A. E., Two-dimensional Bloch-like domain walls in ferromagnetic films, /. Appl. Phys., 40, 2450-2458,1969.

10. Landau L. D. & Lifshitz E. M., On the theory of the dispersion of magnetic permeabil i ty in ferromagnetic bodies, Phys. Z. Sowjet, 8, 153-167, 1935.

11. Néel, L., Théorie du trainage magnetique des ferromag-nétiques aux grains fins avec applications aux terres cuites, Ann. Geophys., 5, 99, 1949.

12. Schabes M. E. & Bertram H. N., Magnetization processes in ferromagnetic cubes, / Appl. Phys., 64,1347-1357,1988.

13. Wegener A. L., The origin of the continents and oceans, Cordon Press, 1977 (originally published in 1920).

14. Will iams W. & Dunlop D. ]., Three-dimensional micro-magnetic model l ing of ferromagnetic domain structure, Nature, 337, 634-637, 1989.


The Scientific Program of the Tokamak de Varennes

C.C. Daughney National Fusion Program Atomic Energy of Canada Limited Chalk River, Ontario, KOJ 1J0

The Tokamak de Varennes is the principal research tool of the Centre canadien de fusion magnétique (CCFM) located at the research site of Hydro-Québec in Varennes near Montreal ' . This article first places the Tokamak de Varennes (TdeV) wi th in the frame of the National Fusion Program (NFP) of Canada, and then describes the scientific program of the TdeV as it has been presented by the staff of the CCFM to the Apri l 1989 meeting of the CCFM Advisory Committee. CCFM has completed Phase I of the experimental program which involved commissioning of the tokamak and the many diagnostic systems required to monitor the plasma behavior. The tokamak has met or exceeded the design targets for magnetic field (1.5 tesla), plasma current (250 kiloamperes) and pulse length (1 second). The TdeV machine has been disassembled in lanuary 1989 for modifications. Phase II of the experimental program wi l l begin in December 1989 with the plasma boundary defined by a magnetic divertor and the power supplies and vacuum system capable of creating a sequence of one second plasma pulses wi th one second between successive pulses. The scientific program for these two phases of machine development wi l l be described and the article concludes wi th some comments f rom the recent Advisory Commit tee report.

National Fusion Program of Canada

The long term goal of the National Fusion Program is to contr ibute to Canada's search for a stable energy source for future generations of Canadians. For decades, it has been understood that the sun obtains its energy f rom nuclear fusion; and for nearly as long scientists have been attempting to obtain control led nuclear fusion in the laboratory. Recently, a new technique has been reported for producing nuclear fusion in metals ("cold fusion") and this claim has gained much media attention. However, as wi th the enthusiasm generated for magnetic conf inement in the 60's, for inertial conf inement in the 70's, and for muon-catalyzed fusion in the 80's, the fact is that all approaches to fusion wi l l demand considerable development and effort. Canada must specialize its contro l led fusion effort not only to use its l imited resources to best advantage, but also to create the best opportunit ies for Canadian industries to access the considerable interna-tional effort in fusion research and development in the near term. Thus the NFP consists of an applied research program which is founded upon cooperat ion wi th the fusion programs of other nations, and which attempts to make use of expertise available in Canada. Atomic Energy of Canada Limited (AECL) manages the NFP on behalf of the Federal Government. Federal funding is through Energy, Mines and Resources' interdepartmental Panel on Energy Research and Develop-ment. The cornerstones of the NFP are two projects — the CCFM ment ioned above and the Canadian Fusion Fuels Technology Project (CFFTP). CFFTP is a joint program of Ontar io Hydro, the Province of Ontar io and AECL. It exploits Canadian expertise in deuter ium and tr i t ium technologies (these wi l l be the first fuels to be used in fusion reactors) as well as Canadian expertise in the technology of remote handling. CFFTP has an excellent record of involving Canadian industry wi th capabilities in these areas in the extensive fusion programs of other nations. CCFM is a joint venture of Hydro-Québec, the University of Québec and AECL. CCFM exploits expertise in electrical and mechanical engineering available at Hydro-Québec and Canatom Inc. CCFM also takes advan-

tage of capabilities in plasma physics available f rom the Universities of Québec and Montréal and from MPB Tech-nologies Inc.

Participation by the electrical utilities in the NFP is a unique aspect of the Canadian fusion effort. Hydro-Québec and Ontario Hydro contr ibute funding and personnel, and provide valuable perspective in project management. Both projects are overseen by Steering Committees and both projects are reviewed annually by Advisory Committees which are com-posed of Canadian and international specialists in the ap-propriate fields. The remainder of this article describes the scientific plan of the CCFM as presented to the CCFM Advisory Committee.

CCFM Scientific Plan

The scientific plan contains three main elements — tokamak development, research on transport and equi l ibr ium in plas-mas, and research on the plasma-wall problem. Machine development may seem unusual as a scientific program, but, in fact, much of the success in control led fusion research has been driven by improvements in hardware. The machine is the experiment. This first element is crucial for Canada in maintaining relevance to international programs and main-taining acceptance by the international fusion communi ty for the Canadian program. The second element, research on transport and equi l ibr ium, is related to the basic understand-ing of high temperature plasmas and is an area of great concern to all magnetic conf inement programs. Indeed, the significance of unknowns in this area has been recently dramatized dur ing the conceptual design stage of a large international reactor experiment (ITER) where expensive ma-chine capabilities were required to cover the scientific un-certainties2. The third element, the plasma-wall problem, refers to the control of processes occurr ing at the boundary between the plasma and the first material surface. The hot plasma is substantially conf ined by the magnetic field, but there remain fluxes of energy and particles directed toward the wall. Materials must be developed and techniques found for handling these considerable fluxes which are of order 1 megawatt/square metre and 1021 particles/square metre/ second. Furthermore, wall materials must be prevented from entering the plasma (as impurities) where they can deplete the fuel and radiate energy f rom the plasma.

Tokamak de Varennes

The design of the Tokamak de Varennes required a com-promise between budget demands and relevance to foreign programs which would allow Canada the international col-laboration which was sought. The solution was a modest sized machine which, with a minor plasma radius of 0.25 metre, is still relevant to larger tokamaks. The modest size permits considerable flexibil i ty compared to larger devices. TdeV has unusually flexible power supplies, a magnetic divertor and plans for non-induct ive current drive. Most importantly, TdeV is conceived to bridge the gap between present tokamaks wi th pulse durations of about 1 second and reactors which must operate continuously. TdeV has capability for 30 second pulses which for a smaller machine are very much longer than the characteristic times of energy confinement, about 10 milliseconds, or the L/R (inductance/resistance) t ime of 100 milliseconds.


Fig. 1. The shaded portion in the center of the figure represents a cross section of the toroidal plasma. Note that the boundary of the plasma is defined by a magnetic separatrix. Magnetic field lines inside this boundary are confined to the central region while magnetic field lines outside this boundary loop around the top and bottom divertor coils. Thus, plasma diffusing across the boundary flows along the field lines and is led to the divertor chambers where it is neutralized and pumped away. Each divertor loop is formed by a triplet of current carrying coils with the two smaller coils carrying current in the opposite corners of the rectangular cross section of the vacuum vessel. These coils produce a force on the plasma current which establishes equilibrium for its horizontal position on a rapid time scale. Outside the vacuum vessel, the many current carrying coils which provide the main toroidal magnetic field and which drive the plasma current may be seen. All coils — inside and outside the vacuum vessel — are provided with water cooling channels.


A special feature of TdeV is the demountable toroidal f ield coils wh ich simplify construct ion and modif icat ion of the vacuum vessel, since the vessel is not " t rapped" by the coils. However, design and fabrication of 128 coil joints, each capable of carrying 100 kiloamperes, did cause some concern. After two years of operation, these joints have now been disassembled successfully. There was no sign of arcing, over-heating or any mechanical problem and thermal performance of the joints was as expected for the 8 second magnet pulses used to date. This means that there should be no problems in extending the pulses to 30 seconds in the future.

Other special featu res of TdeV are the power supply and switch which drive the ohmic heating transformer. This system provides full four quadrant operation, that is, ±24 kiloamperes and ±15 kilovolts. The power supply has produced a maximum plasma current of 283 kiloamperes. Dur ing Phase I, the system was tested by successfully dr iv ing two, one-second tokamak pulses separated by a one second off time. Preliminary studies indicated that the plasmas resulting from the two pulses were very similar to one another, and the power supply funct ioned as expected; so mult ipulse operation should be possible for Phase II. Operat ion of single pulse tokamaks is dominated by particle recycling and energy exchange between plasma and wall at the beginning and end of the pulse. It is important to know how these processes change and what are their t ime scales under mult ipulse condit ions. If desired, the off t ime between pulses can be reduced to one-half second if the capacitor bank for the forced commutat ion is increased.

The surfaces of the vaccum vessel must be carefully cleaned or "cond i t i oned" in order to obtain reproducible, hot, dense plasmas. The TdeV team used proven techniques of glow discharge at higher pressure and radio frequency assisted glow discharge at lower pressure. The former caused surface erosion at the rate of 0.6 nanometres per hour. The latter was characterized by the formation of carbide on the surface. A novel technique of wall condi t ioning was also explored on TdeV, namely, outgassing under ultraviolet radiation. Wi th 28 watts of ultraviolet radiation, 15 monolayers of adsorbed gas were removed per hour and a factor of five improvement in base pressure was attained.

Unti l September 1989, the machine wil l undergo construct ion to add (i) six internal coils, which form the two tr iplet divertor configurations, ( i i ) two addit ional coils which provide the vertical magnetic field for plasma equi l ibr ium on a mil l isecond t ime scale, and (iii) internal liner and getter pumps which provide differential pumping in the divertor chambers (Fig-ure 1). These features wil l permit flexible operation of TdeV in single pulse or mult iple pulse modes for an experimental per iod of about 18 months. The next major upgrade of the TdeV wi l l be the addit ion of a 1 megawatt lower hybrid current drive system at 3.7 gigahertz which is coupled to the plasma by a gril le composed of 64 waveguides. Such a system uses electromagnetic waves at a frequency supported by the plasma (the lower hybrid frequency) to transfer momentum to the plasma electrons and so drive current around the torus. This technique contrasts wi th the usual method of dr iv ing current by means of an electric f ield arising f rom a change of magnetic flux through the center of the torus (i.e. through the hole of the doughnut). For this usual method of current drive, the pulse length is l imited to the order of one second by the maximum magnetic field pressure which can be sustained by materials. The lower hybrid wave driven current can be cont inuous and, in the case of the TdeV, wil l be used to drive a 30 second pulse of plasma current. This wi l l allow investigation of plasma-wall effects with surfaces which are close to saturation. The energy density deposited on the divertor plates dur ing this phase of operation wil l be very high, characteristic of that of large machines like ITER.

Transport/Equilibrium

As explained above, transport and equi l ibr ium are issues of plasma physics fundamental to the magnetic conf inement concept. The TdeV team proposes to specialize in aspects of plasma transport and equi l ibr ium. They propose to study the coefficients of diffusion for both particle density and current density and the coefficient of thermal conduct iv i ty for the electron and ion temperature gradients through various perturbation techniques — both natural and imposed perturbations. Data have been obtained dur ing Phase I using the natural perturbation of the internal kink mode. This tokamak instability causes a small, cyclic bui ld-up and collapse of pressure in the core of the plasma which then results in pulses of heat f lowing to the plasma boundary. This transport of heat was observed wi th an X-ray tomography diagnostic, a six channel submil l imeter interferometer and by six channel optical detection of Bremsstrahlung radiation.

PERTURBATION ONLY

Fig. 2.

0 .08 .16 .24

minor radius (m)

Figure 2a gives the response of the plasma density at one millisecond intervals following admission of a puff of gas into the vaccum vessel at 550 milliseconds. The pertur-bation of plasma density is measured with an interfero-meter system operating at 214 microns. The system has six vertical lines of sight across the plasma cross section and the profiles of Figure 2a are obtained from Abel inversion. The use of two difluoromethane lasers operating at 214 microns permits phase modulated detection on Schottky diodes.

to Diffusion Coeff icient

- K '

/

-

0.2 0.4 0.6 0.8

r/a

1.0

Figure 2b gives the diffusion coefficient extracted from the perturbation profiles. The radial dependence of the source of plasma density due to ionization of the neutral gas is also indicated.


In a second technique, a short pulse of gas was used to perturb the plasma density at the plasma boundary. The gas puff created a source of plasma density which was peaked near the boundary since the mean free path for ionization was much less than the plasma radius. The perturbat ion was moni tored wi th the six channel submil l imeter interferometer (Figure 2). The analysis sugested that the diffusion coefficient is of order 1 metre squared/second which agreed wi th the diffusion coeff icient estimated from the energy balance for these plasmas. The diffusion coefficient appeared to peak strongly toward the plasma boundary although these were still prel iminary results. Other measurements of the diffusion coefficients made dur ing the last months of operation wi l l be analyzed dur ing this present period of construction. For example, trace amounts of a luminum were injected into the plasma f rom laser ablation of thin films and the decay of a luminum line radiation was observed wi th the ultraviolet spectrometer. This spectrometer was also used to obtain profiles of the line intensity of neon admitted as a gas pulse. Both of these experiments must be analyzed wi th the aid of computer codes which are presently under development.

X-ray tomography has been used to study the structure of the internal kink mode3. The system available on the TdeV has five cameras each viewing sixteen chords through the plasma. Systems on other tokamaks often have fewer camera angles available and the results f rom TdeV indicate that quite different conclusions can be drawn f rom reconstructions made from two or five cameras (Figure 3). Indeed, the full five camera analysis suggested that a hot core of plasma was rigidly displaced from the center of the plasma. This picture wou ld be in agreement wi th the Kadomtsev model where the displacement of the core pinches off some of the en-circl ing magnetic field, al lowing these magnetic field lines to reconnect and so redistribute plasma energy on a rapid t ime scale. By contrast, the two camera reconstruction arti-ficially suggested a structure similar to the recently proposed interchange model where a cold bubble of plasma enters into the plasma core. In this latter case, complete tubes of magnetic flux are interchanged and there is no field line reconnect ion dur ing the rapid collapse phase of the insta-bility. Obviously these results f rom the TdeV demonstrate a need for great care in interpret ing tomographic data.

The equi l ibr ium and stability studies performed dur ing Phase I have already prof i ted f rom the flexibil i ty of TdeV referred to previously. Its power supplies have al lowed investigation of fast rampdown of plasma current — an issue of considerable interest to the designers of present machines as a means of conserving the precious volt-seconds of the current driving transformers. TdeV has already attained a disrupt ion free, current rampdown rate of 6 megamperes/second which is three times its L/R rate. The facility is capable of investigating current rampdown rates of up to 20 megamperes/second in the next phase of experiments.

An innovative equi l ibr ium study was begun on TdeV using the electrically isolated limiters to drive vertical currents across the tokamak plasma. Currents which were expected to move the plasma outward did so whi le currents which were expected to move the plasma inward did not. The same apparatus was used to study plasmas which were electrically biased wi th respect to the vacuum chamber walls. Early results indicated that negatively biased plasmas showed many de-sirable properties. Higher plasma density was obtained wi th lower Lyman alpha emission and lower hydrogen pressure. Reduced carbon emission was also observed, wi th reduced Zefi across the entire profi le, and steepening of the density gradient at the boundary. These investigations wil l be pursued dur ing the next experimental phase of TdeV.

Tomography with Various Harmonic Contents

19-3 Shot 5517, lp = 200 kA , n e = 3 x 1 0 m , B T = 1 . 5 T

482.08

M=1 1fe

Fig. 3. The intensity of soft X-rays (1 -15 kiloelectron volt) emitted by the plasma is proportional to the electron temperature and the square of the electron density and thus represents the hot, dense core of the plasma. Five arrays of sixteen detectors each are used to examine the behaviour of the plasma during cycles of the internal kinl; instability (see text). A reconstruction is required to obtain the features of the plasma and the present figures demonstrate the sensitivity of the result upon the number of detector angles available. The figures on the left were obtained using only two detector arrays while those on the right were obtained using all five detector arrays. Note the qualitative features of a cold bubble at the core on the left and a displaced peak on the right.

Plasma-wall Interaction

As stated above, this study is of interest to all magnetic conf inement configurations — tokamaks, pinches, stellara-tors, mirrors, etc. Furthermore, even though TdeV does not have the very hot core of the world's largest machines, it does have an edge plasma similar to that of these larger devices. Indeed, by making use of the magnetic divertor on TdeV, a flux of 10 megawatts/square metre can be attained on the divertor plates — a flux which is comparable to that expected on ITER or a reactor.

A test l imiter head has been used to study thick TiC coatings which have been fabricated by the National Research Coun-cil's materials laboratory in Boucherville, Québec, in collab-oration with staff f rom CCFM. A 200 micron thick coating withstood 17 shots at 15 megawatts/square metre, but failed at higher power because of melt ing of the stainless steel substrate.

Preliminary investigations of erosion and redeposit ion have suggested that these processes are localized. Traces of tita-nium f rom the test l imiter and of molybdenum from a col l imator were found only on those wall samples located close to the respective source. Samples showed a general


asymmetry wi th respect to drift velocity of the ions. Two to five times as much deposit was found on the ion dri f t side as on the electron drift side. Dur ing the next series of experiments, a carousel wi l l be available which permits short t ime exposure of samples to specific tokamak shots. Erosion studies wil l be facilitated by the use of samples wi th implanted marker elements.

Advisory Committee Comments

The Commit tee noted that the Phase II development of TdeV wil l provide a unique and versatile facility for further exper-iments. The tokamak wil l be capable of mult ipulse operation at full current. It wi l l also be possible to operate wi th alternati ng current at the 100 ki loampere level if this proves to be of interest. The tokamak wil l be capable of either l imiter or divertor conf igurat ion and the divertor chambers can be pumped at rates of 104 l i ters/second or fed wi th gas, as desired. (This wi l l permit investigation of a f low reversal of radial impur i ty flux which has been predicted theoretically under condit ions of poloidal f low caused by this asymmetric gas feed.)The internal coils wi l l provide precise positional stability on a submil l isecond t ime scale using either magnetic flux loops or the submil l imeter interferometer as the source of the feedback signal.

The Commit tee encouraged the CCFM to pursue the equil i-br ium studies wi th fast rampdown of plasma current and wi th cross currents fed through limiters or divertor plates. These studies are not generally possible on other tokamaks and TdeV can provide information of much interest to the wor ld fusion communi ty . The CCFM was also encouraged to investigate impuri ty transport across the boundary layer and along the field lines toward the l imiter or divertor. TdeV is equipped wi th good diagnostics for this study and again the results are of interest to all programs. The CCFM should cont inue its materials tests and obtain data on particle recycling and retention under the new condit ions of mult ipulse operation.

The Commit tee recommended cont inued development of the wall conditioning program as a means to reduce the impuri ty levels in TdeV.

The Commit tee emphasized the importance of development, dur ing Phase II, of the long lead t ime elements of future upgrades. Most important is the final design and fabrication (and funding!) of the lower hybrid current drive system which would allow the study of truly steady-state plasmas for the ful l 30 second pulse of the toroidal magnetic field. The Commit tee placed high priori ty on the development of the submil l imeter polarimeter for measurement of the current distr ibution. This diagnostic wou ld give valuable data for the equi l ibr ium studies and especially for the lower hybrid current drive experiments.

References

1. R.A. Bolton, et al., Post Deadline Paper, Proceedings of 12th International Conference on Control led Nuclear Fu-sion, Nice, 1988.

2. K. Tomabechi and ITER Team, IAEA-CN-50/F-I-4, Proceed-ings of 12th International Conference on Contro l led Nu-clear Fusion, Nice, 1988.

3. C. Janicki, R. Décoste and C. Simm, Physical Review Letters, 62, 3038, 1989.

Members of CCFM Advisory Committee

Dr. Gilbert Bartholomew, Consultant. (Chairman) Dr. Charles Daughney, AECL, National Fusion Program. (Secretary) Dr. Donald Dautovich, Canadian Fusion Fuels Technology Project. Dr. Peter Dyne, Consultant. Dr. Akira Hirose, University of Saskatchewan. Dr. jan Hugill, UKAEA, Culham Laboratory, UK. Dr. Miklos Porkolab, MIT Plasma Fusion Center, USA. Dr. Jôrg Winter, KFA Institut fur Plasmaphysik, FRG.

X CAREER OPPORTUNITIES X

CAP offers a service to br ing together career seekers and employers in the physical sci-ences.

Interested candidates should request an infor-mat ion form and return it to

Canadian Associat ion of Physicists 151 Slater St., Suite 903 Ot tawa, Ontar io , K1P 5H3

This in format ion w i l l be kept on f i le and made avai lable to all prospective employers.

Employers should contact the above address and prov ide a brief descr ipt ion of the posi t ion

vd,heskilw / La Physique au Canada septembre 1989 145

Symmetries in Physics — the Unitary Group Approach M. Schlesinger, Department of Physics and R. D. Kent, School of Computer Science, University of Windsor, Windsor, Ontario, Canada, N9B 3P4

ABSTRACT

The unitary group approach encompasses a set of techniques for describing quantum mechanical many-particle systems by incor-porating permutational symmetry directly into the basis functions. By using these bases the algebraic expressions of the matrix elements of operators may be written in terms of the U (n) or SU (m) Racah coefficients for which simple formulae apply. The methods are extendable to systems of arbitrary complexity exhibiting unitary symmetry without the introduction of any additional techniques. The possible application areas of these methods encompasses such diverse fields as fusion, plasma physics, elementary particles, NMR medical imaging and even biotechnology.

I. INTRODUCTION

A consistent goal of modern science has been to construct theories which reflect the inherent beauty and symmetry of nature. The realization that symmetry plays such a significant and fundamental role in nature cannot be emphasized too strongly. Arguments based on these principles have led to the development of successful self-consistent theories spanning the realms of cosmology, biology, atomic and molecular physics and elementary particles.

Our purpose in writing this article is to report on the recent substantial progress made mainly in Canada in one particular approach to problems involving systems of many particles in atomic, molecular and elementary particle realms, the domains of quantum physics. This scheme is referred to as the Unity Group Approach, or UGA.

In quantum physics symmetry principles are used to categorize certain properties of fundamental particles and of systems built up from them. Usually, this is manifested explicitly in the form of mathematical expressions whose algebraic components represent appropriate fundamental objects and concepts (e.g. positions, momenta, energy, spin, etc.). The manner in which various compo-nents can be coupled together, for instance to form increasingly complex expressions, is constrained by the symmetries expressed by physical theory. Symmetry methods typically suggest efficient, elegant techniques for studying the structure and behaviour of mathematical expressions. Common properties of groups of expres-sions are used then to simplify calculations and for interpretations in a physical sense.

Clearly, in attempting to present such a rich topic area, we had to omit a great amount of detail. In so doing we risk trivializing certain concepts for the more sophisticated reader while at the same time presenting an inadequate basis for appreciating the techniques to the uninitiated.

Further, with few notable exceptions we do not refer directly to any workers, including the authors in particular. To all those who have contributed so much to the development of UGA we especially apologize.

II. THE ANGULAR MOMENTUM CALCULUS.

The cornerstone of atomic and molecular spectroscopy is the angular momentum theory originally developed by E. Wigner1 and G. Racah2. Through this theory great progress has been made in explaining the complex spectra and chemical properties of many-electron systems and nucléons. The Racah-Wigner theory also


provides a paradigm for the construction and interpretation of the unitary group approach as wil l be seen presently.

The simplest and best understood quantum system is the hydrogen atom with its single, positively charged proton nucleus and nega-tively charged electron, both of which possess an intrinsic spin and magnetic moment. To an excellent approximation (due to the fact the proton mass is about 1836 times that of the electron) this system can be treated as a single particle, the electron, orbiting a fixed point in space.

In classical physics a particle is defined as existing, deterministi-cally, at specified points in space; intuitively a material object. In the quantum domain this notion is replaced by a wave-based viewpoint in which one speaks only of the probability of finding some part of a wave-particle in a certain spatial volume. The important components in actual calculations are then the wavefunc-tions, to describe the particle structure and behaviour, and various mathematical operators which describe the interactions with the external world.

The hydrogen atom is described by the one-electron Schrodinger equation

^ i / r = [ - V 7 2 n + U ) = E i|i In this form i|j is the wavefunction of the electron, whose mass is |i, and X is referred to as the Hamiltonian operator which is immedi-ately related to the total energy, E, of the system.

The Hamiltonian is made up of two terms, the kinetic and nuclear potential energies. These are expressed as a differential operator, V-', and a function, U, which depends only on the radial distance from the nucleus to a point in space. (For the moment we ignore the electron spin). The V|J are then solutions of a differential equation. The obvious requirement of stability, that is the electron remains in orbit about the nucleus rather than collide with it or even fly off into a free trajectory, gives rise to the quantum conditions first stated by N. Bohr. Under these constraints the permitted wavefunctions pred ict that, on average, the electron wi 11 be fou nd only i n d iscretely allowed orbits (as proposed to a continuum of orbits at arbitrary radii).

The solutions can be rewritten in the discrete form i l ^ ^ u ^ Y j , (v=1,2,-,<=°; 1=0,1-,v-1 ;m=-l,-l+1,-,l) reflecting the spherical spa-tial symmetry evident in this case; u H is a function of radial distance from the nucleus while the Yi, called spherical harmonics (Legendre polynomials), are functions of angles only on spheres of unit radius. The Schrodinger equation is then transformed into^4»v ln l = E ,i|/t|tT|

where the wavefunctions are called eigenfunctions ancfthe ener-gies E„t are eigenvalues.

The important thing to note about the structure of these solutions is the categorization of families of finite numbers of eigenfunctions into groups labelled by v, the principal quantum number, and I, the orbital angular momentum, each group having the same energy, E If one represents the Hamiltonian and, therefore, the energy eigenval-ues in matrix form with rows and columns labelled by the quantum numbers v, I and m then the structure of these matrices is said to be block-diagonal with the same value of Eu| appearing along the digital in (21+1 )x(2l+1) sub-matrices labelled by fixed vand 1 only. The invariance of the model system and its Hamiltonian under 3-dimensional rotations is seen in terms of transformations which mix only functions of the same v and I.

Another important point has to do with the evaluation of the eigenvectors. The solutions were first obtained using algebraic

methods. Thus, forgiven vand I, each of the 21+1 m-labelled func-tions can be explicitly calculated for given radius and angles. This requires the evaluation of complicated functions, however, which is a time-consuming process. In contrast, by using group theoreti-cal techniques one can generate each of the m-labelled functions by recursively operating on a selected function, say i|ipll, with a so-called "ladder" or shift operator.

The selected function is chosen by the criterion that it be relatively easy to calcu late (compared to other possible functions). The ladder operators are formed from elementary group theoretical functions called generators, such as

y-il>„lm = V (l+m)(l-m+1 )/2 i|/ The repeated application of these operators generates a sequence of ijjii|m for m decreasing from 1,1-1 and so on. The coefficient arising from i f is typically quite easy to evaluate.

The point of this is that the calculations required are both simpler and faster to perform and, as well, one is working with conceptual elements, such as the generators, which themselves arise from the physical symmetries of the problem. Another way of stating this is that symmetry considerations suggest methods for reorganizing the approach to a problem, usually by breaking the problem into smaller ones each of which is more easily solved.

Now an important theory of physics states that systems tend to orient themselves (arrange their internal structure) in ways which minimize the total energy. In the quantum domain, states of minimal energy (lowest v and 1 ) occur with higher probability than otherwise. Although a complete solution to the Schrodinger equa-tion requires the inclusion of an infinite number of eigenvectors, most of these occur rarely and can usually be ignored. In many cases excellent approximations to the complete solutions can be achieved by including only the first few families of eigenvectors.

The relevance of finite approximation methods is seen immediately when one considers the next simplest case, two or more electrons moving in a central field including the effects of inter-electronic repulsion.

A typical Hamiltonian used to describe an N-electron system is written

N N jnr = i s [ - v y 2 ^ + u ( ) + s v M i ^ l a l

(a| i = 1 i< j= l

where the first summation is made of single particle operators operating on the wavefunction of the i'h particle only and V . is a two-body interaction potential, such as the electron-electron repul-sion. The many-particle wavefunctions are built up from products of N single-particle wavefunctions 4>, which are solutions of the one-electron Schrodinger equation. Finally, the labels {<*) are used to distinguish the various combinations of product states.

In the case of a single electron the wavefunctions can be more or less easily determined depending on the degree of utilization of symmetry. This is reflected in the labelling used to clarify these functions, or states. It would be natural, then, to look for types of symmetry which provide labels |a| which simplify the solution to our more general problem, just as in the single electron case.

If one assumes that electronic repulsion is relatively small com-pared to the nuclear attraction (a good assumption based on the fact that stable multi-electronic atoms do exist) then the effect of the V(

on the solutions to the Schrodinger equation can be found using methods from perturbation theory. In such treatments one looks for solutions when V |=0. The resulting wavefunctions are just the products mentioned previously.

However, not all such products represent acceptable solutions because of the Pauli exclusion principle, the consequenceof which is that at most two electrons can be described by the same spatial wavefunction. Further, this important principle gives rise to a new symmetry of nature, that of intrinsic particle spin (which is inextri-cably tied to the existence of moments as well). Each single-electron

wavefunction is augmented by additional labels, hence "Ki ms„=,t\.i mXs,T< where xs(r is a two-component mathematical device called a spinor. The spin quantum numbers has a value of 1/2 while its magnetic projection label <x=±1/2.

One simple method for producing product states which obey the Pauli principle istoconsider linearcombinationsof productswhich are anti-symmetric under the interchange of any two particle labels. For example, for the states <|/(1 )and t|/(j), i and j denoting an arbitrary particle number, the combinations <J»(i)i|)(j)±i|i(j)i|j(i) represent a sym-metric (+) or anti-symmetric (-) state depending on whether the sign of the product state changes with an interchange of the labels i and j.

In cases where N is greater than 2 properly anti-symmetrized linear combinations of products can be formed from so-called Slater determinantal states.

Since electrons are indistinguishable from one another there must be no explicit dependence on particle number labels built into the Hamiltonian. Nevertheless, the type of symmetry called permuta-tional, or interchange of particle number labels, figures prominently in categorizing the eigenfunctions. We shall discuss this symmetry further below.

Early workers chose to exploit the symmetry properties of the single electron case through the three-dimensional rotation group, R(3), which possesses obvious immediacy. In the absence of inter-elec-tronic interactions the product wavefunctions can still be adapted to R(3) symmetry.

The symmetry adaptation of the product functions amounts to finding linear combinations of such functions which preserve the Pauli principle constraint while at the same time obeying the rules of invariance under transformations of the R(3) group. This leads directly to the angular momentum theory developed by G. Racah and E. Wigner.

In this scheme the notion of "vector-coupling" is introduced. Geometrically each wavefunction is viewed as a vector in a special mathematical space called Hilbert space. The angular momentum of each vector is written t . Vector coupling is obtained by consid-ering restricted cases of vector addition between two states, hence n=T+f. Algebraically this takes the form, using only the spatial parts of the complete wavefunctions,

1 , + 1 LM = E C . „ , * „ L M ^ M = m + m '

where the C's, which embody the quantum constraints on the allowed values of L, are referred to alternatively as Clebsch-Gordan, Wigner or vector-coupling coefficients.

It is a powerful result indeed which states that the properties of a product of single particle wavefunctions can be deduced from linear combinations of a product of single particle wavefunctions

this being derived from the wave property called superposi-tion. The most obvious and immediate benefit of this is a reduction in the amount of computation required to evaluate the wavefunc-tions and other quantities made up from them.

The Wigner coefficients are fundamental quantities of the invari-ance properties of the group. These coefficients arise whenever the type of wavefunction coupling described above applies. Further, this coupling method works not only for vectors in ordinary 3-dimensional space but also for vectors in other abstract spaces, in particular the space of spin symmetry. Indeed the coefficients which arise in the construction of product states adapted to permu-tational symmetry are just the Wigner coefficients of the spin vector coupling. Fully labelled wavefunctions are written

To couple three or more wavefunctions together requires more complicated coefficients of higher symmetry. These include the Racah coefficients, themselves constructed from Wigner coeffi-cients. Unfortunately, use of spin and angular momentum coupling


in R(3) eventually results in definitions of product states which are not uniquely labelled. This latter point, the solution of which is to increase the number of labels (e.g. fractional parentage) used to denote states, proves to be a major stumbling block in the use of Racah-Wigner methods to solve complex problems involving many particles.

At the level of construction of the symmetry adapted many-particle basis states the fundamental quantities used in computations are the Wigner coupling coefficients. At the level of evaluation of tensor operators, for one- and two-particle interactions, the fundamental quantities are the Racah coefficients.

For N-particle transformations other coefficients, the 3N-j symbols, arise in a natural and systematic way. General and specialized formulae exist for the simple 3N-j symbols (the Wigner 3j and Racah 6j coefficients). For higher symmetry symbols there are none, however, and their computation is laborious. It is worth pointing out that a large body of literature has been devoted, over the years, to methods for calculating these coefficients.

^=^+^oulomb+^pin-orbit+<^pin-!pin+^quadrop<,leH"""

we re-express this in terms of unit irreducible, spin-independent tensor operators

V N k

expanded in terms of the Gel'fand (SN-adapted) basis of U(n). These operators are generalizations of the Y1 introduced previously. The matrix elements of the Vk can be evaluated using the U(n) group generators, E . Thus, using the well-known Wigner-Eckart theorem with standard1 notation we have

i l k / , l ' m i r 1 i * ' i v <{a<};SNMN| V* |{a};SNMN> = E (-1) [ _ , ! q m J < a ] l l * W

J,' . <{a<};SNMN| E y |{a};SNMN>

The Hamiltonian may be expressed, therefore, in terms of the E. operators (generators),

III. THE SU(2) UNITARY GROUP APPROACH

The immediate objective of the unitary group methods in many-particle quantum physics is to build into the wavefunctions as many of the symmetry properties of the system as possible from the outset. In the molecular and nuclear regimes the Slater determinants ensure antisymmetry (Pauli's exclusion principle) with no addi-tional symmetry properties other than the (approximate) single particle symmetries. The unitary group methods go further than this by ensuring that each basis set member in itself is a total spin (isospin) eigenfunction.

The mathematical foundations for obtaining complete sets of spin-adapted functions and evaluating matrix elements were developed by early workers in the Soviet Union, North America and else-where. For references prior to 1979 we direct the interested reader to the proceedings of the Bielefeld workshop on unitary group methods.3 One comprehensive exposition on group theoretical methods in quantum physics is that of Biedenharn and Louck.4

The point of departure of the UGA is the fact that rather than opt for immediacy one follows the path of fundamental beauty. The fact that this beauty produces significant benefits in the computational aspects of application is not a mere side product; rather, an inherent property.

Early attempts at implementing the UGA were hampered by the seemingly unmanageably complicated mathematical expressions that were required in actual calculation. Recent work by mostly the Canadian scientific community, including (by no means exclu-sively) the current authors, has enabled one to implement the UGA in theory as well as in practice resulting in ease of calculation and enabling the application of the UGA to problems lying outside the immediate applicability of traditional methods.

At least in the atomic and molecular regime both the traditional and UGA methods wi l l ultimately lead to the same energy levels and other predictions. Keeping in mind that G. Racah initially devel-oped his methods without regard to group theory (only later did he make the connection and thus pushed forward our understanding of the fundamental symmetries of nature) it is not surprising that ultimately the fundamental building blocks are the appropriate Wigner and Racah coefficients. In the UGA those are coefficients of a special class amenable to immediate determination whereas in the traditional approach the coefficients require resorting to either tables or complicated algebraic expressions.

«* = W i j + R f c M K ^ E u - ^

where [ij] and |ij;kl] represent, respectively, one- and two-electron integrals.

Other relevant operators, besides the Hamiltonian, can also be expanded in terms of the generators. Examples include N-body interaction operators and the projection operators used to produce those linear combinations of Gel'fand states which are eigenstates of X. By expressing the projection operators in terms of permuta-tions the generators act as transposition operators and, in general, one can write

V: N n

: n s i= i /V"i»i

E " i n

where denote numerical factors corresponding to particu-lar transpositions (e.g. point symmetry group transformation coef-ficients).

For electronic spin-orbitals (group structure-U(2Ti) U(ri) ® SU(2)) basis states of total spin can be defined graphically by employing vector coupling calculus or Weyl-Young tableaux:

| { a * } ; S N M N > = Ï

/n ! • S ( - l ) n |a,mi>

i = l 1 1

,N N

n ^ i = l :

pa i rs

( - 1 ) " n y 2S-+1 i = l 1

no pa i rs

s k + 2 s k + 1 - s k - i sk_2

-o — I

"N

I I m k + 3 " k + î "•k-l " "2

Qt

a i

m, m, m f i

<>i

« i n

M «

IV. ELEMENTS OF THE THEORY*

('Sections IV and V may be skipped by the non-specialist.)

Starting with a Hamiltonian for a generic N-particle U(n) system such as

V (a). ONE-BODY OPERATOR MATRIX ELEMENTS FOR SU(2)

The one-body operator matrix elements require the generator matrix elements <|a'|SM|E i | |a|SM>, expressed graphically (i>j) as


—o——

s s s s î + + + +s,+s,+ + This graph can be decomposed in terms of Racah (6-j) coefficients such as. for instance

H) s, + s- + 1 S• s,

S , . , S;

The decomposition of <E > is expressible as a single product of (i-j+1 ) Racah coefficients, each of which involves the square root of a rational number.

V(b). ONE-BODY MATRIX ELEMENTS FOR U(n)

The extension of the above regimen to U(n) follows in an analogous fashion, leading to graphs with similar appearance though more complicated algebraic expressions. Graphically we have

"V p^i P„ V i

' 1

X Each node represents the coupling of r particles labelled (jl (the symmetric state) to the SN irrep p t yielding p , and is expressed as a U(n) Wigner coefficient. Completely labelfed Gel'fand states are constructed according to

I p ^ r ' - p p = s r < P r - l r l r

r > * I P T _ i " ' P i >

with appropriate (anti)symmetrization performed by the Young operator y. The U(n) Racah coefficients are then constructed in the usual fashion.

The Racah coefficients can be easily evaluated using so-called hooklength formulae derived with the aid of Weyl-Young tableaux. These can be adapted so that the group labels (pTand r ) can be used directly in calculations.

V(c). TWO-BODY OPERATOR MATRIX ELEMENTS FOR U(n)

The representation of two-particle interactions is accomplished using products of two generators. Until recently values of these could be computed only using time-consuming iterative tech-niques. In SU(2) it was found that matrix elements of such generator products are expressible as the sum of at most two terms (called singlet and triplet terms), each of which is a product of easily computed Racah coefficients. The derivation of these is accom-plished easily using graphical methods of analysis.

What is especially revealing and useful about the unitary group approach using the Gel'fand basis is that the same degree and nature of simplification extends to all orders, that is to an arbitrary number of particles exhibiting arbitrary spin symmetry. This dem-onstrates the essential role of permutation symmetry in the quantum domain.

VI. APPLICATIONS AND IMPLEMENTATIONS

Presently the main "users" of the unitary group approach have been quantum chemists. These workers use it in conjunction with the configuration interaction (CI) method. In this method one seeks an approximate solution to the Schrodinger equation using an expan-sion in terms of an incomplete basis set in a subspace of the N-

electron Hilbert space. The expansion coefficients are determined variationally and this calls for the solution of a matrix eigenvalue problem for the matrix representation of the Hamiltonian operator. The N-electron basis functions (configurations) are expressed in terms of 1 -electron functions (orbitals). The unitary group approach provides a systematic, efficient way for the construction of a suit-able N-electron basis in terms of the 1-electron basis.

In conventional CI the Hamiltonian matrix is computed explicitly in a given order, and saved for use in the iterative solution of the eigenvalue problem. Each element of this matrix is computed as a linear combination of 1- and 2-body integrals corresponding to suitable components of the Hamiltonian operator which operates upon the orbitals. The unitary group approach can be used to derive the formulae for these linear combinations.

Modern CI calculations, for example those pertaining to medical NMR applications, often use expansions of 0(107) terms and this poses a serious organizational problem in computation. Sequential calculation of the Hamiltonian matrix elements requires random access to the integrals while sequential processing of the integrals produces, essentially, random sequences of matrix element contri-butions. The speed of calculation depends critically on the access speed to huge amounts of information.

The difficulties are overcome using the Direct-CI approach by avoiding the explicit computation and storage of the Hamiltonian matrix. Instead, in each iteration the integrals are handled in a se-quence producing contributions to the matrix elements which are utilized in the iterative procedure for the solution of the eigenvalue problem and then discarded. An essential point in this approach is the need for an efficient way for the identification of the matrix elements (row and column indices) to which each contribution be-longs. This is yet another aspect of the problem to which the unitary group techniques provide a crucial contribution.

In summary, because of this last characteristic as well as because it facilitates the calculation of the individual matrix element contribu-tion, UGA (particularly in its graphical form) has made possible the generalization of the Direct-CI method to virtually arbitrary many-electronic states and more general Cl-expansion types.

VII. PUTTING IT ON THE COMPUTER

The emergence of computing technology with sufficient power to enable the implementation of methods such as the unitary group approach, for the first time present opportunities to obtain detailed, ab initio model calculations for complex many-particle systems. These are clearly of great interest in that it is through the study of these models that one obtains greater understanding of the basic theory of complex systems and, further, one is led to develop particular methods which are of use in more practical areas; for example, industrial applications or medical research.

The current generation of physicists has developed a sophisicated appreciation of what constitute useful hardware/software combina-tions for specific problems. Among the more promising technolo-gies in the case of the unitary group approach are the parallel and distributed computing systems.

The pertinent issues in this development concern the choice of a configuration of processors (the network topology) which is best suited to the rapid communication of data and instructions through-out the network and the production of high-quality, reliable and maintainable systems and programs adapted to the parallel pro-gramming environment.

This area presents tremendous opportunities for Canadian develop-ment.

VIII. SUMMARY

It ought to be stressed again that were it only for calculational ease one achieves using the UGA one may argue that considering


present day computational capabilities any method that leads to the correct results is acceptable and so the UGA is merely one of many methods which an individual may choose to use.

We wish to take issue with such viewpoints and point to UGA's inherent beauty and overall usefulness in the broadest sense of its possible applications. Were it only for the former it would be reason enough for its thorough study. Now that we also have the latter no worker can afford being ignorant of it.

Admittedly the UGA may not always be superior to other methods in use for particular problems. Those are identified by special simplifying features appropriate to the problem. It has been con-cluded, nevertheless, by a number of workers interested in prob-lems characterized by large numbers of particles with higher degrees of symmetry that the UGA affords current science the best vehicle for obtaining detailed models of those truly complex sys-tems.

Indeed the fact that the same computational and theoretical appa-ratus which works so well and in agreement with traditional theory also extends, without the necessity for additional enhancement or modification, to regimes of arbitrary complexity emphasizes once again the beauty of the UGA.

ACKNOWLEDGEMENT

We wish to acknowledge the continued support of the Natural Sciences and Engineering Research Council (NSERC) of Canada. One of us (M.S.) wishes to express his deeply felt indebtedness to the late Giullio (Yoel) Racah.

REFERENCES

1. E. P. Wigner, in Quantum Theory of Angular Momentum, Eds. L. C. Biedenharn and H. Van Dam, pp. 87-133 (Academic Press, New York, 1965).

2. G. Racah, Phys. Rev. 62, 438 (1942); 63, 367 (1943); 76, 1 352 (1949).

3. The Unitary Croup for the Evaluation of Electronic Energy Matrix Elements, edited by ). Hinze, Lecture Notes in Chemistry, (Springer-Verlag, Berlin, 1981), Vol. 22.

4. L. C. Biedenharn and J. D. Louck, Angular Momentum in Quantum Physics: Theory and Application, vol. 8; and, The Racah-Wigner Algebra in Quantum Theory, vol. 9, in Ency-clopedia of Mathematics and Its Applications, Ed. G.-C. Rota (Addison-Wesley, Reading, Mass., 1981).

APPENDIX A. NOMENCLATURE

: Hamiltonian operator. This is related to the interaction energy between states.

^vimw • Wavefunction of particle with principle quantum number v, orbital and spin angular momentum 1 and s and their projections m and a.

C,Lmi-m- : Wigner coefficient used in vector coupling of two wave-functions

R(I,I2I3;I12I23I]23) : Racah coefficient used in coupling three wavefunctions.

Vk : Unit irreducible tensor operators. Vq : tensor components related to the spherical harmonic functions, Ym.

iôr E..: Generators of the R(3) or unitary groups.

[653220000I of the U(9) group, corresponding to the [65322| par-tition of the symmetric group S, g. Such matrix elements would arise, for instance, in quadropole type transitions. Using Weyl-Young tab-leaux we consider:

. . . . 7 7 . . 7 9

. . 7 7 8 . . 7 8 8 < . . 9

. 7 ^7.1 7̂.9

. 7 9 >

8 9 9 9

Below we list the U(6) - U(9) labels of the Gel'fand states in t« :rm of SN partition inc ices.

Bra Ket Row =

Subgroup 6 5 4 3 2 1 0 6 5 4 3 2 1 0 Row =

Subgroup 9 1 1 0 1 2 0 4 1 1 0 1 2 0 4 8 1 1 0 0 2 1 3 0 2 0 0 2 0 4 7 1 0 1 0 2 0 3 0 1 0 1 2 0 3 6 0 0 1 0 2 1 2 0 0 1 0 2 1 2

The "angular momentum" (YVL) graph is written as:

Ket

[11012 04]

Bra

- [0200204] - [0101203] -- 0 . 0 . 0 -

U. 1 -o

0+

o+

- Ô -

[0010212]

+ [1100213] + [1010203] +

This graph decomposes into a product of three subgraphs, each of which represents a Racah coefficient. These are easily evaluated using the hooklength formulae resulting in the terms:

l " l ' l ' ' 7 ' 2 4 ' 7 " 2

5 2 " 2

2 27 . 6 . 5

. 7 . j j .

15 r— — y 42

81

The important thing to note regarding this computation is that it involves a limited number of terms in a single product and each term is directly computable using formulae derived from the pattern calculus of the Weyl-Young tableaux.

The same calculation can be performed iteratively using the Lie algebra relations lEÊ ^ ^ Ô ^ E -SÊ^ to decompose the genera-tor products into products of single-step form E t , . ; however, even for this simple example the number of contributing (i.e. non-zero) terms is eight, illustrating the amount of redundant computation inherent in this approach.

APPENDIX B. NUMERIC EXAMPLE

In order to demonstrate the use of the graphical decomposition results we compute a matrix element of the generator product E79E79 for two basis states from the Gel'fand labelled irrep


CAP Lumonics Awards

At the 1989 CAP Congress at the University of Cuelph, three graduate students received Lumonics Awards for their presentations at a special session held on Monday evening, June 26. The "extended summaries" of their presentations are reproduced below.

Oscillator Studies of Flux Dynamics in Ceramic High Temperature Superconductors

by David /. Baar Dept. of Physics, Queen's University

One of the possible mechanisms l imit ing the ult imate critical current in ceramic superconductors involves the mot ion of magnetic flux lines. This dissipative mot ion is reduced by the presence of flux p inning sites in the ceramic. A simple oscillator technique has been developed for studying flux line mot ion in high temperature superconductors. The tech-nique involves measurement of the resonance response of an oscillating sample of ceramic superconductor, in the presence of an applied magnetic field. Resonance frequency and damping measurements provide a means of detecting the viscous mot ion of flux lines in the superconductor.

In the oscillator experiments (figures 1 and 2), a beam-shaped sample of ceramic superconductor was suspended from four wires, and was made to swing in the presence of a vertical magnetic field. Oscil lations were driven by an alternating current f lowing along the beam. The induced voltage across the sample was used to detect the mot ion of the sample. The results of the experiments have been quite dramatic. Above the superconduct ing transition temperature, the res-onance frequency of the oscillator is determined by the mechanical properties of the suspension wires, and by the suspended mass. Below the transition temperature, pinned magnetic flux contr ibutes to the stiffness of the osti l lator, so that the resonance frequency increases (figure 3).

If the flux is completely pinned, it makes no contr ibut ion to the damping of the oscillator. If the flux is completely de-pinned, it produces no damping aside from a small resistive contr ibut ion. In the "st icky" regime between these extremes, flux line mot ion produces increased damping. This is observed as a peak in the oscillator damping as a funct ion of temper-ature. In the same regime, the hysteretic mot ion of the flux lines produces an increase in the asymmetry o f the resonance.

For the YBa2Cu,07.6 samples which have been tested, two damping peaks were observed,' one immediately below Tc, and another at lower temperature. The temperature at wh ich the latter damping peak occurs decreases linearly with in-creasing oscillator driving force (figure 4), and this is what wou ld be expected for a depinning process. The temperature at which the higher temperature damping peak occurs is independent of the driving force on the oscillator. Therefore, this damping peak is thought to be the result of the intragrain critical currents, and its temperature dependence reflects that of the upper critical field rather than the depinning of flux lines.

s u p p o r t •vacuum line t h e r m a l link

I © ® I I v / V I • ft / . ft ft : t _ J

sample p l a t f o r m

magnet •.liquid helium."

Fig. 1. Schematic illustration of the swinging beam technique. Fig. 2. Apparatus for the swinging beam experiment.


M •

t 1 1 1 | 1 . ° D D ° ° q ° O 0 d L

r -r-j 1 * 1 1 1

£ 180 -' ° ° n 1 1 Q

D ! 1 • 1 1 • 1 o 160 - 1 1

• , • | <u 1 • ! 3 1 cr 140 - 1 i 0) L_ Li. 1 i

120 - 1 | i <u 1 i u c 1 1 o 100 - 1 i c 1 i o 1 | i <u 80 1 • • • • • • a

(X

60

1 1 1 1 . | . 1 1 «

i i i i . i t (X

60 1 I 0.12 -

1 1 1 i i 1 1 i

0.10 - 1 1 1 i

0.08 1 1 1

a 1 1 "i i \ 1 i - 0 . 0 6 - 1 1 i

1 1 i • i

0.04 - • i • • 1 o • 1

0.02 • a • 0 0 ° ° ° | i D • • • „

1 ! a-0.00

1 • 1 • 1 > 1 1 • i i . i t 0.00 1 i

1.5 -1 1

° !

i

• ,—, • N i i i

fr 1 0 -• J

i t

B i • i i • i E i i E >»

• i • |

« 0.5 • o D ° 0 ! • j • i J o • i 1 • '

• i

0.0

1 • 1 1 1 1 1 1 1 1 1 n O l I I • n ai B

IB (mA T)

Fig. 4. Temperature dependence of the depinning transition temperature for samples of various starting particle sizes.

The influence of grain size on flux pinning in the ceramic superconductors is of some interest. If the flux is pinned at the grain boundaries of the ceramic, the flux pinning should be strongly influenced by grain size. In our oscillator exper-iments, we have used samples of grain size <38um up to 75um. No effect of grain size on the depinning temperature was observed. This suggests that the pinning sites are intrinsic wi th in the grains. This postulate is supported by the existence of distinct damping maxima.

Studies are now in progress on the frequency dependence of the flux pinning. Future work wil l involve experiments on materials other than the 123 compound, and also single crystals and oriented ceramics.

Reference

1. D.J. Baar, and J.P. Harrison, Physica C 157 (1%9) 215.

20 40 60 80 100 120 Temperature (K)

Fig. 3. Resonance frequency, dissipation, and resonance asym-metry as observed in a typical run of the experiment.


Tetracritical Behaviour of CsMnBr,

by T.E. Mason, M.F. Collins, and B.D. Caulin McMaster University, and J.Z. Larese Chemistry Department, Brook haven National Laboratory Upton, N.Y.

CsMnBr3 has a hexagonal lattice structure belonging to space group P63 /mmc.' The Mn ' 2 ions form a simple hexagonal lattice wi th an Mn-Mn spacing of 3.2 Â along c and 7.6 Â in the ab-plane. The spin j Mn*2 moments interact anti-ferromagnetically; below about 20 K an XY-like anisotropy restricts them to the ab-plane.2 This system is therefore an experimental realization of the XY antiferromagnet on a stacked triangular lattice.

CsMnBr3 undergoes a cont inuous transition to long range antiferromagnetic order at TN = 8.32 K.3 The nature of this transit ion has been of some interest because the ordered state is non-coll inear. Due to lattice frustration the ground state is one in which the spins are rotated by 120° f rom site to site in the ab-plane. There is no frustration along the c-axis and the spins are aligned antiparallel in this direction. This state is characterized by a chirality or "handedness" as well as a vector and it has been suggested that the critical indices should belong to a universality class distinct f rom the standard XY model w i thout chirality.4 Critical phase transitions are classified according to the dimensionality of the system (three in this case), the dimensionality of the order parameter (sublatt ice magnet izat ion for an ant i fer romagnet) , and whether or not the interactions are long range. For the chiral XY antiferromagnet to differ f rom the XY universality class the second dist inct ion wou ld have to be extended to the symmetry of the order parameter. The unusual exponents predicted for CsMnBr, by Monte Carlo simulations4 have been conf i rmed by recent neutron scattering measurements.5'6-7

In order to better understand the behaviour of this novel magnetic system we have used elastic neutron dif fraction to determine the phase diagram in a magnetic field applied along the (100) direct ion. The measurements were carried out on the H5 triple-axis spectrometer at the Brookhaven National Laboratory. Magnetic fields up to 6.5 T were applied using a split coil superconduct ing magnet. Further details concern-ing the experimental set-up may be found in the literature.8

The temperature dependence of the (-57}-,1) and f ^ l ) magnetic Bragg peaks in 4.2 T field are shown in Figure 1. Two phase transitions are clearly visible at 9.0 ± 0.1 K and 7.5 ± 0.1 K. The inset shows the f ield dependence of the (220) and (002) reflections at T = 7.0 K. The increasing intensity is a signature of an increasing ferromagnetic component parallel to the applied field. We have systematically investigated the temper-ature and field dependence of the magnetic Bragg peak intensities and the resulting phase diagram is shown in Figure 2. The structure of the two ordered phases is shown sche-matically in thediagram. The low temperature, low field phase (I) is the 120° structure, and as the field is increased this six sublattice system collapses to the four sublattice system wi thout chirality that constitutes phase II. These results are consistent wi th zero temperature classical predictions.9

The transition at T = 8.32 K, H = 0.0 T is a tetracritical point. Mult icr i t ical points are known to exhibit unusual critical properties10 so the fact that the zero field transit ion is a tetracritical point could account for the observed critical indices5-67 wi th in the scope of the conventional universality classes. Further work on other chiral antiferromagnets such as Ho and VC12 is clearly warranted to determine if the tetracrit icality of the zero f ield transition is a feature common to all chiral systems.

6 8 Temperature (K)

Fig. 1. The temperature dependence of the (j,j,1) and (f,f,1) magnetic Bragg peaks in an applied magnetic field of 4.2 T. The inset shows the field dependence of the (220) and (002) Bragg peaks for T = 7.0 K.

H ( T )

Fig. 2. The phase diagram of CsMnBr3 in a magnetic field applied along (100). P denotes the paramagnetic phase. The structures of the two ordered phases (I and II) are indicted schematically on the diagram.

References 1. J. Goodyear and D.J. Kennedy, Acta. Cryst. B 28, 1640

(1974). 2. B.D. Gaulin and M.F. Collins, Can. ). Phys. 62, 1132 (1984). 3. M. Eibshutz, R.C. Sherwood, H.S.L. Fsu, and D.E. Cox, AIP

Conf. Proc. 17, 864 (1972). 4. H. Kawamura, J. Appl. Phys. 63, 3086 (1988). 5. T.E. Mason, B.D. Gaulin, and M.F. Collins, J. Phys. C 20,

L945 (1987). 6. B.D. Gaulin, M.F. Collins, and T.E. Mason, Physica B, in

press. 7. T.E. Mason, B.D. Gaulin, and M.F. Collins, Phys. Rev. B

39, 586 (1989). 8. B.D. Gaulin, T.E. Mason, M.F. Collins, and J.Z. Larese, Phys.

Rev. Lett., 62, 1380 (1989). 9. A.V. Chubukov, J. Phys. C 21, L441 (1988).

10. M.F. Collins, Magnetic Critical Scattering, Oxford Univer-sity Press, (1989).


Analysis of Sputtering From a TiC Coated

by D.A. Poirier, B.L. Stansfield, W.W. Zuzak, L. Pelletier, R.G. Saint-lacques and the Tokamak de Varennes Team Centre canadien de fusion magnétique*

Introduction

Nuclear fusion research is advancing to the point where reactor-sized devices are now being designed. However, a fundamental problem remains: that of the choice of materials for the components which wil l come into contact wi th the plasma. In order for a magnetically conf ined plasma to reach thermonuclear temperatures, the number of impurit ies in the plasma must be kept to a min imum. Impurit ies enter the plasma primari ly when energetic particles interact wi th wall and l imiter materials. This causes two problems: firstly, the plasma is degraded and its temperature lowered by the presence of the impurities, and secondly, the wall itself is damaged in the process.

One important interaction is sputtering, where a plasma ion or impuri ty ion strikes a surface and thereby causes one of its atoms to be dislodged, or "sputtered". This is basically a transfer of momentum mechanism. The sputtered atom then penetrates a certain distance into the plasma, where it is ionized and transported further toward the interior, thus contr ibut ing to the impuri ty level of the plasma.

An edge spectroscopy diagnostic is used on the Tokamak de Varennes to examine sputtering f rom a test l imiter coated wi th t i tanium carbide. Some preliminary results wi l l be given, along wi th the conclusions we have drawn from them to date.

Description of the Diagnostic

In order to test the behaviour of various materials in the hostile environment of a fusion plasma, we constructed a vacuum manipulator assembly, wh ich allows a test l imiter head to be inserted into the plasma and retracted for study. An optical diagnostic has been mounted which allows observation of the l imiter head.

The purpose of this diagnostic is to make an absolute mea-surement of the rate of product ion of atomic t i tanium at the surface of the test l imiter which is in contact wi th the plasma in the Tokamak. The spatial variation of the atomic density in front of the l imiter along wi th power deposit ion measure-ments on the l imiter itself can then be used to define the plasma edge properties in this area.

The radiation f rom a region near the test l imiter is focussed onto an array of optical fiber bundles. The light is passed through separate interference filters tuned to a wavelength of 4453Â , corresponding to a transition in atomic t i tanium. This f i l tered light is then detected and amplif ied by photo-

* T h e Cen t re canadien de fus ion magnét ique is f u n d e d by A tomic Energy of Canada Limited, Hyd ro -Québec , and l ' Inst i tut nat ional de la recherche sc ient i f ique.

Test Limiter in the Tokamak de Varennes

multipl iers whose output is digit ized, mult ip l ied by an ab-solute calibration factor, and stored. Thus output readings are of actual emissivity, photons.s-'rrr2. All data acquisit ion is tr iggered and control led by the operation of the Tokamak, with a 10 kHz sampling rate over the duration of the shot, typically 800 ms.

The power deposited on the test l imiter head was calculated by measuring the bulk temperature rise dur ing each Tokamak discharge wi th a series of thermocouples embedded below its surface.

Results

The emission of atomic t i tanium from the test l imiter is maximum near the surface and then decreases exponentially into the plasma. This decreasing signal is due to the ionization of the sputtered atoms as they are ejected f rom the limiter surface. From the exponential decay in front of the target, the mean free path for ionization of the sputtered t i tanium atoms is calculated. This, along wi th the ionization rate coefficient, gives a relation for the electron density in front of the limiter.

The power density deposited onto the test l imiter head also has an exponential variation wi th radius. Using this, we can derive another relationship between ne and the electron temperature, Tc. These two relations are used together to determine unique values for ne and Te. The value found for the electron density using a simple analysis wou ld seem to be too small, whereas the temperature value is loo high. This is an area of ongoing study.

There is found to be a small but non-negligible background signal at the wavelength we are observing, most likely due to oxygen radiation. This radiation shows the characteristic shape of sawteeth. An unexpected and as yet unexplained phenomenon has been observed, wherein the phase of the modulat ion of the signal undergoes a change producing an inversion of the signal at the edge of the plasma.

Conclusion

An assembly which allows insertion of a test-l imiter into a hot plasma has been developed. In addit ion to its usefulness in the study of various materials, it is also well adapted for measuring the properties of the edge plasma. Measurements of sputtering and power deposit ion can be used to determine unique values for the plasma density and temperature. In addit ion, the fluctuations of the radiation f rom the edge have shown very regular "sawteeth", which we have correlated wi th other diagnostics. These display a surprising phase inversion near the edge.


CAP Affairs/Affaires de l'ACP

The 1989 CAP Medal for Achievement in Physics to Paul Redhead

Paul Redhead

by Brian C. Gregory

High vacuum techn iques , and in particular ultra-high vacuum techniques, are of fundamental importance in numerous branches of phys-ics. Paul Redhead is one of the most important pioneers in this area.

After graduating f rom Cam-bridge towards the end of the war, Paul went to work for the A d m i r a l t y . He r e m a i n e d there three years, work ing on magnetrons and R.F. tubes for radar. He was lured f rom the United Kingdom in 1947 by a job offer f rom NRC.

Work ing first on microwave tubes at NRC, he became in-terested in ultra-high vacuum technology as a means of producing and maintaining for a relatively long t ime clean metal surfaces. These, Paul tells me, interested him because of an underlying feeling for the enormous industrial impor-tance of catalysis.

He established the Electron Physics Croup at NRC in the early fifties. He built up the Croup, hir ing Pete Hobson, Bob Armstrong, Ernie Kornelsen, Alec Szabo, and bringing in many post docs and summer students. This was when I first met Paul, as a summer student along wi th )ohn Alcock, Dan Krupka and )ohn Earnshaw. I believe Paul strongly inf luenced my career and probably those of other summer students, post docs and colleagues.

The Electron Physics Croup, which later became a Section, developed modern vacuum technology along with, at the time, Westinghouse and MIT. Curiously, this development was a North-American phenomenon.

Perhaps his work on magnetrons at the Admiralty led him to the invention of the Inverted Magnetron Gauge, published wi th Hobson in 1958, and the Magnetron Gauge, now baptized the Redhead Gauge, in 1959. Three Redhead Gauges are still on the moon, having gone up on the Apol lo mission. They were ideal for the first measurements of the moon's atmos-pheric pressure of 10 8 Torr dur ing the day and 10 ,2 at night.

Paul used ultra-high vacuum techniques to explore surface phenomena, and for over a decade from 1958, he studied chemisorpt ion of molecules on metals and electron stimu-lated desorption. His theory of thermal desorption, published in 1962, won him the "Citat ion Classic" in 1980 (at the moment, this paper has 765 citations). Another frequently cited paper on the interaction of slow electrons wi th chemisorbed oxygen laid the foundations for electron stimulated desorption, an important f ield of modern surface science.

Vers la fin des années soixante, Paul a inventé une petite source, extrêmement astucieuse, d' ions plusieurs fois ionisés (jusqu'à 10 - 15 fois). Ce dispositif convient comme source pour les accélérateurs. Les ions sont piégés dans une con-f iguration de champs électr ique et magnétique. Ils sont des cibles faciles pour les électrons d 'un faisceau d'énergie modeste, et leur état de charge monte avec le temps. Paul a exploité ce dispositif en mesurant les niveaux d'énergie de divers phénomènes.

Paul est l 'auteur ou le co-auteur d'au dessus de 60 articles dans les revues scientifiques ou des chapitres de livres. Huit de ces papiers ont été cités plus de 50 fois et 3 plus de 270 fois. Il a 8 brevets et, avec Hobson et Kornelsen, a écrit en 1968 la "B ib le" de l'ultra-vide, " T h e Physical Basis of Ultrahigh Vacuum".

Très actif dans la "American Vacuum Society" (AVS), Paul était éditeur du " journal of Vacuum Science and Technology" de 1970 à 1974 et président de la Société en 1967. Il en est membre honor i f ique pour la vie et a mérité sa médail le "Medard W. We lch " en 1975. Actuel lement il préside le comité sur l'his-toire de l'AVS.

Paul a beaucoup d'autres distinctions: membre de la Société royale du Canada, Fellow of the American Physical Society, Fellow of the IEEE, and so on.

He has been a loyal corporate member of NRC, doing his duty as administrator. In particular, he was a very successful, well liked and respected, director of the Physics Division f rom 1973 to 1986.

Paul has worked very hard for thermonuclear fusion in Canada as chairman of the NRC Advisory Commit tee (1975-1980) and for high energy physics as chairman of the NRC Advisory Board on TRIUMF since 1975. In semi-retirement, he is very active, work ing hard on a revised version of his book, and as an advisor to NRC on cold fusion, among many other projects.

Response by Paul Redhead

Mr. President, Honoured Guests, Friends and Colleagues

When the President's letter arrived informing me that I had been chosen for this medal I was at first astonished and then delighted. I feel very honoured to be chosen by the CAP to join the group of outstanding Canadian physicists who have been awarded this prize in the past, and I can only aspire to the standard of excellence they have attained.

I graduated f rom Cambridge in wart ime when the fate of all science graduates was dictated by C.P. Snow, who was the British government's czar of scientific manpower. He directed me into an Admiralty laboratory where I was for-tunate to work for Alec Thomson, one of the co-inventors of the proximity fuse. When the war ended I transferred to a newly-formed Admiralty laboratory to work on the devel-opment of mil l imetre-wave magnetrons under Robert Sutton, the inventor of the reflex klystron.

Coming to Canada in 1947 to escape the gloom of post-war austerity in the UK, I was very fortunate to join NRC at the start of a period, lasting more than a decade, when NRC, under Steacie, was one of the best labs in Canada if not the world. The degree of intellectual freedom and stimulation at this t ime in NRC was quite unique amongst national laboratories. Al though I was in an engineering division I was permit ted to form a group concerned wi th electron physics and to pursue a course which combined basic research wi th the development of new instruments and techniques. A considerable body of technology related to ultra-high vacuum came out of this group as well as quite basic research on surface physics. This experience has taught me that it is unwise, and usually inefficient, to separate applied and basic research.


I was very lucky to move into the field of surface physics in the early sixties at a t ime when the advent of UHV technology was rapidly increasing our ability to create and maintain surfaces in a wel l-character ized state. Surface science was then a sparsely populated field of research and it was possible to know all the practit ioners around the wor ld. These were excit ing days for experimentalists, unfortunately our theoretical colleagues did not join us in surface physics for another decade.

In the late sixties, after twenty-f ive years of research, I went back to Cambridge to get my trade-union ticket, the PhD, on the basis of published research. Scientific respectability had befallen me at last.

Having become respectable I was moved out of the laboratory in the early seventies to become a scientific bureaucrat. There were many pleasures in research management and in par-ticular the direct ion of the Division of Physics at NRC for thirteen years was both enjoyable and rewarding. Less en-joyable was the responsibil ity for implement ing cut-backs.

I consider myself to have been fortunate beyond my just deserts in a career in research and research management, and particularly lucky in the many scientific colleagues wi th w h o m I have worked over the years. I owe a great debt of gratitude to the five presidents of NRC under whom I have worked for permit t ing me great intellectual f reedom and for tolerat ing my idiosyncrasies.

Finally, I have been particularly fortunate in being awarded the Medal for Achievement in Physics and I am most grateful to the CAP for this recognit ion.

The 1989 Herzberg Medal to Tom Tiedje

by Brian G. Turrell

Tom Tiedje was born and raised in Sarnia, Ontario. For his high school education he a t tended Sarnia N o r t h e r n Collegiate School where he s t u d i e d French, Ge rman , La t in , G r e e k and M u s i c . A r m e d w i t h th is classical learning he enrol led in Engi-neering Science at the Uni-versity of Toronto where he studied f rom 1969 to 1973, taking the 2nd Prize in the CAP Prize Examinat ion in 1972 and the 1st Prize the fo l lowing year. He then went to UBC wi th an NSERC 1967 Science Scholarship and studied for the M.Sc. and Ph.D. degrees under the supervision of J. Carolan and R. Haering respectively. His Ph.D. work on TTF-TCNQ demonstrated the blend of expertise that has characterized his research career: extraordinary experimental skill coupled wi th considerable theoretical insight. I think that all the aforementioned ed-ucational institutes can reflect wi th some pride that they had some part in Tom's development.

After UBC, Tom accepted a position in 1977 on the Research Staff of Exxon Corporat ion where he established himself as an internationally recognized authority in the science of amorphous semiconductors. His accomplishments were sev-

Tom Tiedje

eral and inc luded: the discovery (with B. Abeles) that superlattice-l ike structures can be made f rom amorphous semiconductors and that these structures exhibit quantum conf inement effects, analogous to conventional crystalline superlattices, creating a new subfield for semiconductor research; the demonstration that the disordered structure of amorphous semiconductors puts a fundamental limit on the efficiency of amorphous solar cells that is significantly lower than that for crystalline devices; the first simple physical explanation for dispersive charge transport in disordered semiconductors, now widely used and sometimes referred to as the TROK (Tiedje Rose Orenstein Kastner) model, and the discovery that the drift mobil i ty in amorphous sil icon was an order of magnitude higher than previously believed, the practical consequence being that the material is suitable for driving the matrix-addressed l iquid crystal displays needed for flat panel computer monitors. He was made Group Head in 1983 at a relatively tender age.

By 1987, Tom had decided to turn to an academic career, and accepted from several offers the one put to him by my colleague and former Head, David LI. Williams. Later that year, Tom was made a Fellow of the American Physical Society " for his contr ibut ion to the understanding of electrical trans-port in amorphous semiconductors and his pioneering work on amorphous semiconductor superlattices".

Safely back in academe at UBC, he has in a couple of years significantly inf luenced the direct ion of science in the De-partment and the University. He was primarily responsible (with a little help from his friends including Lawrence Young of the Electrical Engineering Department, the Deans of Ap-plied Science and Science, the VP Research and personnel in the Cominco and Microtel corporations and NSERC) for the acquisition of a Molecular Beam Epitaxy machine. In fact, this was an excellent example of how Industry, NSERC, and the University can work together. Tom installed the machine in a remarkably short t ime and his research group are busy doing experiments on it. He set up (with R. Cline) a Scanning Tunnel ing Microscope (the first one in Canada west of Halifax), a version of which is being marketed. He has also been doing experiments at the Brookhaven National Synchrotron Light Source.

Obviously Tom is an exceptionally gifted experimental phy-sicist, but he is also an excellent teacher able to explain scientific concepts to students at any level, lay people and (importantly) Provincial Cabinet Ministers and MLAs. So, what is he like as a person? In fact, he has a most pleasant personality meeting every situation with equanimity and always wi th a nice sense of humour. I do understand, however, that some aggressiveness is shown on the hockey rink where he is known to dispense body checks impartially to senior and junior colleagues alike. I also know personally that he is no mean runner and he loves hiking in the mountains.

Tom's work has been recognized in many ways, but the highest award that he wil l have received so far is the Herzberg Medal. I am delighted that this gifted physicist and delightful colleague should be so honoured, and I am sure that his friends in Canada and other countries wil l join me in offering Tom our sincere congratulations for being awarded this most prestigious prize.

Response by Tom Tiedje

I am absolutely delighted to receive the Herzberg Medal f rom the CAP. I thank you, the members of the CAP, for this honour. I wou ld like to share the credit for this award wi th my wife Glenna, who has in a very real sense supported my work; wi th the people at UBC who educated me, in particular R.R. Haering, A.J. Berlinsky, J.F. Carolan and W.N. Hardy; and wi th my collaborators at Exxon Research and Engineering. At Exxon I was fortunate to have been able to work w i th one of the

1 5 6 Physics in Canada September 1989

best collections of condensed matter physicists in the world, including three former leaders of the old RCA Laboratories, Ben Abeles, George Cody and AI Rose.

As you know from Brian's introduct ion, two years ago I returned to Canada after work ing in industry in the U.S. for almost 10 years. If you don' t mind, I wou ld like to share with you some of my perspectives on this career change.

The university impresses me as being an effective and low cost place to do research. The university operates on the principles of individual initiative and individual responsibility, which is the best system for encouraging people to produce at a high level. The NSERC funding scheme is well run even though the money may be a little thin. Also NSERC is happy to cut off people who are low producers: this doesn't happen as easily in industry or in government. The combinat ion of teaching and research is a powerful one. Not only is research essential for keeping advanced education up to date and relevant, but teaching and the involvement of students fa-cilitate the research process. Of course, this assumes one has enough t ime left after preparing and giving lectures, to do research.

Now I wou ld like to say something about the U.S. and Canada. First, I wou ld guess that there are as many Canadian physicists in the U.S. as there are in Canada. That makes about 5% of the total in the U.S. One of the biggest differences wi th regard to how science is done in the two countries, is the almost complete absence of scientific research in industry in Canada. This is a very serious structural problem, that is in my opin ion self-consistent wi th the large degree of foreign control of

The CAP Committee to Encourage Women 1. Introduction

The purpose of this commit tee is to encourage women to pursue careers in Physics. In 1988-89 the Commit tee met three times in Toronto. Because of the predominantly Ontar io membership of the Committee, efforts were made to expand the membership to include "corresponding members" f rom areas other than Toronto.

As in previous years, the activities of Commit tee members have been largely self-initiated wi th the Commit tee providing information and support. Consistent wi th direct ion f rom the Counci l , the activities of the Commit tee were increased dur ing the year and included:

• providing material on women in science to interested Physicists, and material on careers in Physics to girls;

• making presentations at career days at conferences, high schools and universities to promote Physics as a career (eg, University of Guelph, Science Teachers Association of Ontar io Conference);

• support ing York University's Physics Workshop and send-ing planning details for such an event to Physics Depart-ments in Universities, CEGEPS and Colleges; and

• repeating a survey of university Physics Departments to determine the number of female students in Physics.

2. Evaluation

Expansion of the membership of the Commit tee has led to broader dissemination of information regarding careers in Physics for women. Also individual members, who may not be able to attend meetings in Toronto, nonetheless participate by raising awareness of the issue wi th in their own organ-ization. Whi le it is dif f icult to assess the success of this approach, there is a growing interest in the issue of gett ing more women into Physics careers. By providing information (eg, f rom the survey of Physics Departments) the Commit tee

Canadian industry. Industrial research is an act of faith. There is an immediate cash outlay, wi th an uncertain future gain. The top management of the company must be constantly reassured first hand, by people they know and trust, that the research dollar is being spent well. It helps a lot if the research and development lab is close to headquarters. In our case, all too often headquarters is outside the country.

I worry about the quality of jobs available to Canadian science and engineering graduates. Finding a job is not a problem because a good science or engineering graduate can always f ind a job. The dif f iculty is in f inding a quality job where you can do something interesting and significant and at the same t ime earn a good salary.

Canadians should be concerned if their university graduates in science or engineering need to leave the country to f ind interesting work. This is bad for future enconomic growth and for our ability to remain independent. One promising alternative for the enterprising young scientist or engineer is to create his or her own job. In this regard, one is much more likely to be successful if one has something new or state-of-the-art to offer. This is where the quality of the university system is critical. To fulf i l l their educational re-sponsibilities well the universities must be at the forefront of scientific knowledge.

Numerous other comparisons could be made of how science is done in the two countries and in the industry/university sectors. However, I wi l l stop here. Thank you very much for your attention and for the medal.

Physics — A Report on 1988-89 Activities

can help ensure that the numbers of women entering Physics are known. In addit ion, speakers are provided for career days and similar events in public schools and universities.

Plans for an in-depth study of the issue were not pursued because of diff iculty obtaining the necessary funds. The need for a "Directory of Women Physicists" has been established, but a detailed plan to assemble such a directory has yet to be produced.

Future Plans

Further expansion of the Commit tee to include addit ional corresponding members f rom other provinces and organ-izations is proposed. Activities as carried out for the past several years wi l l be cont inued relying primarily on initiatives of individual Commit tee members wi th in their own organ-izations. For example, several Commit tee members participate in Affirmative Act ion Committees wi th in their organization. Emphasis wi l l cont inue to be on the provision of information and support to girls considering careers in Physics, to Phys-icists interested in the issue of women in Physics and to women in Physics. The current members wil l cont inue to serve for 1989-1990.

Summary In 1989-1990 the visibility of the Commit tee has been main-tained with the University communi ty through distr ibut ion of the questionnaire on female students in Physics and the Physics Workshop Documentat ion. In 1989-1990 these activ-ities wil l be fo l lowed up on. In addit ion efforts wi l l be made to liaise more closely with groups such as WISE, KIWIS, SWIST, which have women scientists as members. By jo in ing forces to provide speakers and information it should be possible to raise the visibility of all of these groups.

Ann McMillan, Chair


Fifty Years of Nuclear Fission

A special symposium to mark the 50th anniversary of the discovery of nuclear fission was held dur ing the annual meeting of the Canadian Nuclear Association and the Can-adian Nuclear Society, in Ottawa, 1989 June 4-7. The early developments, more recent achievements and future pros-pects for fission technologies, were described by six of the most eminent and distinguished participants in this 50-year old saga.

As the first speaker at the symposium, Bertrand Goldschmidt, put it, "For Canada it really began in February 1940, a few months after the start of the Second Wor ld War, the day the French Prime Minister Edouard Daladier gave his consent to the dispatch to Norway of a French secret agent to acquire the wor ldwide stock of heavy water, a paramount decision in the race toward the chain reaction started a year earlier fo l lowing the discovery of fission." Goldschmidt, who had been hired by Marie Curie as her personal assistant in 1933, jo ined the Anglo-Canadian atomic project at its start in Montreal. He left his posit ion as head of the Chemistry Division at Chalk River in 1946 to return to France as one of the founders of the French Atomic Energy Commission, and later became Chairman of the Board of the International Atomic Energy Agency.

Another Chalk River pioneer, Leslie G. Cook, related remi-niscences going back to his research days in the late 1930s at the Kaiser Wi lhe lm Institute in Berlin and the Cavendish Laboratory in Cambridge. His talk contained many fascinating reflections on the early history and later development of the Canadian nuclear power program (for example the sometimes baleful inf luence on it of polit ical considerations). His com-ments on the crucial contr ibut ions to the discovery and understanding of fission by three women scientists, Irene Curie, Ida Noddack and Lisa Meitner were particularly i l luminating.

Geoffrey Hanna, now retired as Director of Research at Chalk River, and a former President of the C.A.P., discussed the very substantial impact of the discovery of fission upon the development of physics research in Canada, f rom fission physics itself through nuclear structure studies wi th heavy ion accelerators, to the investigation of interatomic forces by neutron scattering techniques that were pioneered at Chalk River in the 1950s. Mr. Hanna concluded his talk by reviewing some of the initiatives that could have a major impact on physics in Canada in the future, and which have their roots in the discovery of fission. Examples include the Sudbury Neutr ino Observatory and the McMaster Nuclear Reactor upgrade.

John Foster, a past President of Atomic Energy of Canada Ltd., gave a detailed account of " the greatest thing in the field of energy since cooked meat": the development of nuclear power. Specifically he concentrated on what he called the Second Stage — the development and general application of the essentially simple fuel cycle power reactors that provide virtually all of our nuclear power today.

The final talk of the June 5th segment of the symposium was to have been given in person by Alvin Weinberg, a past Director of the Oak Ridge National Laboratory. Unfortunately, Dr. Weinberg was prevented by a sudden (and happily temporary) illness f rom attending the symposium, but his paper was read on his behalf by the organizer of the sym-posium, Dr. Malcolm Harvey. Entitled "The Second Fifty Years of Nuclear Fission", Dr. Weinberg's paper emphasized that the two primary aims of nuclear power — inexhaustible energy via the breeding of fuel and economical ly competi t ive elec-tricity — have both been amply demonstrated. "But despite these extraordinary successes, nuclear energy hangs in the

balance, and is all but dead in many countries. What went wrong and how can we set it right?". Dr. Weinberg dealt wi th these questions wi th admirable clarity and a profound understanding of both the justifiable and the unjustif ied anxieties of today's environmentally conscious society.

A f i t t ing conclusion to this 50th anniversity celebration was provided on June 6th, when one of the wor ld- renowned pioneers of nuclear medicine, and now Lieutenant Governor of Saskatchewan, Her Honour Sylvia Fedoruk, guided us on an enthusiastic and entertaining "walk down memory lane", recalling the important developments in medical therapies and diagnostics brought about by the advent of fission. Dr. Fedoruk herself played a leading role in many of these advances, and she certainly made this reporter feel proud of Canada's (and Saskatchewan's!) achievements in this area.

The full proceedings of this symposium are to be published in an elegant format appropriate to the tremendous signif-icance of this first half century of fission. Malcolm Harvey and his organizing team deserve a hearty vote of thanks for ensuring that Canada's role in this saga wil l not be forgotten.

Gerald Dolling

Nominations for CAP Representatives

to Other Organizations

At the June 19, 1988 meeting of the CAP Counci l , a policy and procedure were established for the nomination of CAP representatives to other organizations. (See p. 42 of the January 1989 issue of Physics in Canada.)

We are currently seeking suggestions for a representative to the organization described below. (Please complete and return the form on p. 168).

NRC Committee on International Scientific and Technological Affairs.

The mandate and responsibilities of the Committee are described in the fol lowing extract f rom the invitation received from NRC's Vice-President, International Relations, Dr. B.A. Gingras.

"Le CNRC représente presque depuis toujours la commu-nauté canadienne au sein de plusieurs organismes interna-tionaux. Pour être en mesure d'assumer ce rôle, nous avons mis sur pied un comité à très large représentation (CASTI). Le mandat de ce comité est à la fois de conseiller et de prêter son assistance au CNRC dans l 'élaboration et l 'application des règles de conduite qu' i l s'est données en ce qui concerne la participation canadienne aux activités d'organismes scien-tifiques et techniques non gouvernementaux internationaux. Pour nous assurer que le comité représenterait bien la communauté canadienne, nous nous sommes toujours adres-sés aux sociétés nationales pour solliciter la nominat ion de candidats ayant une réputation et une stature leur permettant de jouer un rôle utile dans le soutien actif des intérêts canadiens.

"La principale responsabilité du comité en question est de superviser notre réseau de comités nationaux canadiens pour différents organismes internationaux. Le CASTI peut toutefois s'attendre à jouer un rôle qui déborde le cadre des intérêts qu' i l a dans des activités scientifiques ou techniques plus spécifiques. Par exemple, dans l 'élaboration de programmes multidisciplinaires comme le programme international sur la géosphère-biosphère et la Décennie internationale pour la réduct ion des désastres naturels; dans la sauvegarde des principes de coopérat ion scientif ique et; dans l'examen des questions d'éthique liées au progrès scientif ique."


The 1988 CAP Salary Survey by Peter Kirkby Ontario Hydro

A grand total of 573 responses to the 1988 CAP Salary Survey were received by the CAP Head Office. Of these responses, 520 were processed. Those not processed were predominantly responses with no entry for " the year of graduation" or for "salary". The histogram below shows the salary distribution of those processed.

Medians and quartiles were found for the four categories of the Survey, which were subdivided into 16 sub-units. The results of the Survey are given in 16 tables. These are listed below under the appropriate category and sub-unit.

Category Sub-unit Table Category Sub-unit Tabl Qualifications Bachelors Degree 1a Region of Employment Atlantic Provinces 3a

Masters Degree 1b Quebec 3b Doctorate Degree 1c Ontario 3c

Current Employment Academic 2a Prairie Provinces 3d Government 2b BC and Territories 3e Industry 2c Outside Canada 3f Graduate 2d Sex of Respondent Male 4a Other 2e Female 4b

In each table, the medians and quartiles are given for five-year periods, based on the year of graduation. The final entry in a table covers the entire period of the table, which normally covers the period 1944-1988. The medians are not reported if there are less than 3 in a period, to maintain confidentiality of the salaries. Quartiles are only reported if there are 7, or more, in a period.

Such surveys have many uses, so the interpretation is left to the reader. However, should you have suggestions on future salary surveys, please notify the CAP Head Office. Many thanks to those that responded.

15 £ <D c

&<5-

M E 3 z

80

70

60

50

S 40

30

2 0 -

10

0 " T - T T - T - T - J~1 J ~ L

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Salaries (k$)

Histogram of the 520 salaries processed in the 1988 CAP Salary Survey. La Physique au Canada septembre 1989 159

Table la. Qualifications: Bachelors Degree

Graduation Year Number Lower

Quartile Median Upper Quartile

$ $ $

54-58 2 59-63 1 -

64-68 3 64,800 69-73 2 -

74-78 3 56,500 79-83 4 42,300 84-88 26 12,000 15,000 17,500

54-88 41 12,250 17,350 44,000

Table lb. Qualifications: Masters Degree

Graduation Year Number

Lower Quartile Median Upper

Quartile $ $ $

49-53 5 58,000 54-58 3 68,000 59-63 4 57,446 64-68 8 46,143 54,000 60,000 69-73 7 46,000 46,000 48,000 74-78 9 25,000 38,000 45,000 79-83 20 11,500 14,800 30,000 84-88 17 12,000 14,000 19,000

49-88 73 14,000 33,302 53,000

Table le. Qualifications: Doctorate Degree



$ $ $

39-43 1 44-48 19 74,500 76,700 86,000 49-53 55 69,800 75,000 83,000 54-58 49 62,600 69,000 76,500 59-63 81 61,000 65,000 71,000 64-68 74 53,000 60,000 64,500 69-73 53 45,500 51,500 57,000 74-78 45 40,000 43,000 48,000 79-83 22 34,000 36,300 40,000 84-88 6 34,000

39-88 405 50,000 61,000 71,000

Table 2a. Current Employment: Academic

Graduation Number Lower Median Upper Year Quartile Quartile

$ $ $

44-48 11 75,000 76,700 84,000 49-53 34 70,000 78,000 85,000 54-58 37 60,000 68,980 77,803 59-63 56 60,000 65,000 70,000 64-68 49 53,000 59,000 63,000 69-73 29 43,000 48,000 52,500 74-78 34 35,000 42,000 45,000 79-83 12 34,000 37,000 41,000 84-88 6 31,000

44-88 268 47,672 60,000 70,000


Table 2b. Current Employment: Goverment

Graduation Year

Number Lower Quartile Median Upper

Quartile $ $ $

44-48 6 77,000 49-53 16 67,563 71,000 73,000 54-58 15 66,000 67,000 70,000 59-63 22 62,000 65,000 72,000 64-68 17 58,000 62,000 76,000 69-73 18 48,000 55,000 57,000 74-78 10 42,000 47,300 56,532 79-83 8 35,000 40,000 40,000

44-83 112 55,000 62,580 71,000

Table 2c. Current Employment: Industry

Graduation Year

Number Lower Quartile

Median Upper Quartile

$ $ $

39-43 1 44-48 1 -

49-53 5 80,000 54-58 2 -

59-63 6 70,000 64-68 10 51,000 58,512 60,000 69-73 7 45,000 45,000 51,500 74-78 6 56,040 79-83 8 35,000 37,000 42,300 84-88 6 30,000

39-88 52 42,300 56,800 70,000

Table 2d. Current Employment: Graduate


Quartile $

Median $

Upper Quartile

$

64-68 69-73 74-78 79-83 84-88

64-88

2 1 2 16 34

55

11,000 11,000

11,000

12,000 13,000

13,000

14,500 15,(XX)

15,000

Table 2e. Current Employment: Other


Quartile $

Median $

Upper Quartile

$

44-48 1 49-53 59-63

5 2

65,000

64-68 69-73 74-78 79-83

8 7 5 2

54,000 53,000

62,000 58,000 46,000

64,800 64,(300

84-88 3 18,000

44-88 33 35,400 53,865 64,800

Table 3a. Region of Employment: Atlantic Provinces

Graduation Year Number

Lower Quartile Median Upper

Quartile $ $ $

49-53 1 54-58 8 63,000 67,000 68,980 59-63 4 62,000 64-68 9 51,700 56,000 57,000 69-73 5 41,000 74-78 5 42,300 79-83 1 -

49-83 33 44,000 56,000 62,000

Table 3b. Region of Employment: Quebec



$ $ $

44-48 1 49-53 6 72,000 54-58 13 56,000 62,000 70,000 59-63 16 60,000 65,000 69,219 64-68 15 60,000 60,000 65,000 69-73 19 48,000 50,000 55,000 74-78 21 40,000 43,460 55,000 79-83 10 11,500 36,300 45,000 84-88 17 11,000 15,000 17,350

44-88 118 40,000 55,000 63,000

Table 3c. Region of Employment: Ontario

Graduation Year


Quartile $ $ $

39-43 1 44-48 11 76,000 76,700 84,000 49-53 31 69,000 78,000 83,000 54-58 23 67,000 72,000 78,400 59-63 39 61,700 64,650 69,000 64-68 38 54,000 60,000 63,000 69-73 26 45,500 53,000 60,000 74-78 21 33,302 42,500 47,300 79-83 17 14,500 30,000 37,000 84-88 17 12,000 13,000 20,000

39-88 224 45,500 61,000 70,000

Table 3d. Region of Employment: Prairie Provinces

Graduation Year


Quartile $ $ $

44-48 4 82,000 49-53 5 73,000 54-58 4 77,803 59-63 13 70,000 71,000 72,000 64-68 11 53,000 64,500 65,000 69-73 8 47,000 56,900 57,000 74-78 4 43,000 79-83 3 45,000 84-88 3 11,000

44-88 55 48,000 65,000 71,900

3e. Region of Employment: British Columbia and the Territories


Quartile $

Median $

Upper Quartile

$

44-48 49-53 54-58 59-63 64-68 69-73 74-78 79-83 84-88

44-88

1 7 5 9 7 3 1 3 3

39

69,800

59,000

45,000

75,000 68,000 60,000 53,000 48,000

13,000 15,000

58,000

75,264

69,000

69,000

Table 3f. Region of Employment: Outside Canada



$ $ $

44-48 2 49-53 8 65,000 71,000 71,371 54-58 1 -

59-63 5 80,240 64-68 4 90,000 69-73 1 -

74-78 5 47,672 79-83 12 28,320 35,400 36,000 84-88 9 17,700 18,000 28,320

44-88 47 28,320 45,000 65,000

Table 4a. Sex: Male


Quartile Median Upper

Quartile $ $ $

39-43 1 44-48 19 74,500 76,700 86,000 49-53 55 67,700 73,000 80,000 54-58 52 62,000 69,000 76,000 59-63 84 60,205 65,000 71,000 64-68 76 53,000 60,000 64,500 69-73 59 46,000 51,000 56,900 74-78 55 37,600 43,000 48,000 79-83 39 16,000 32,000 37,000 84-88 40 12,000 15,000 23,000

39-88 480 43,850 59,500 70,000

Table 4b. Sex: Female



$ $ $

49-53 2 59-63 1 -

64-68 8 54,000 58,512 64,800 69-73 3 45,000 74-78 1 -

79-83 7 14,800 34,500 36,000 84-88 7 13,000 13,000 15,000

49-88 29 14,800 40,000 54,000


CAP Council and Division Executives 1989-90 *President, A.A. Of fenberger , University of Alberta •Past President, L.C. Caron, Université de Sherbrooke •Vice-President, R.L. Armst rong, University of Toronto •Vice-President Elect, R.M. Lees, University of New Brunswick •Honorary Secretary-Treasurer, A.). A lcock, National Research Council Director — Full Members, R.C. Barber, University of Manitoba Director — Affiliate Members, P. Char leswor th , Energy Mines and Resources Director — Student Members, Crystal Plume, University of Waterloo Director — Corporate Members, R.J. Kriegler, Bell Northern Research

Division Chairmen Aeronomy and Space Physics, , Atomic and Molecular Physics, G.W.F. Drake, University of Windsor Canadian Geophysical Union, D.E. Smylie, York University Condensed Matter Physics, T. Timusk, McMaster University Medical and Biological Physics, C.J. Thompson , Montreal Neurological Institute Nuclear Physics, H.R. Andrews, Atomic Energy of Canada Optical Physics, R.M. Lees, University of New Brunswick Particle Physics, R. Wo loshyn , TRIUMF Physics Education, C.G. Deacon, Memorial University Plasma Physics, P. Cou tu re , IREQ, Hydro-Québec Theoretical Physics, R.B. Mann , University of Waterloo Industrial and Applied Physics, P.S. V incet t , Xerox Canada Ltd. Surface Science, S. Ingrey, Bell Northern Research

Councillors/ Conseillers

British Columbia (1) R. Keeler, University of Victoria (2) L.E. Wa l tham, University of British Columbia

Alberta (1) H.A. Buckmaster, University of Calgary (2) Wytze Brouwer , University of Alberta

Saskatchewan and Manitoba (1) J. Vail, University of Manitoba (2) E.L. Tomusiak, University of Saskatchewan

Ontario — Southwest (1) F.S. Razavi, Brock University (2) ).B. Atk inson, University of Windsor

Ontario — Central and North (1) P. Kirkby, Ontario Hydro (2) D.K. Hasell, York University

Ontario — East (1) P.A. Kalyniak, Carleton University (2) D.B. McLay, Queen's University

Québec — Nord et Ouest (1) M. Sutton, McCill University (2) A. MacGregor , RCA Inc.

Québec — Sud et Est (1) R. Marchand, INRS — Energie (2) P. Amio t , Université Laval

New Brunswick & Newfoundland (1) W.R. Ross, University of New Brunswick (2) M ichae l M o r r o w , Memorial University

Nova Scotia and Prince Edward Island (1) Y.N. Joshi, St Francis Xavier University (2) G. Stoink, Dalhousie University

At Large (1) A.C. McMi l l an , Ontario Hydro (1) C. Samson, University of Toronto (2)

Editor — Canadian Journal of Physics: R. Nichol ls , York University Editor — Physics in Canada/La Physique au Canada: G. Do l l ing , Atomic Energy of Canada Ltd. Executive Secretary — Secrétaire Exécutif: M.L. Jento

• M e m b e r of Executive C o m m i t t e e (1) Te rm ends |une 1990 (2) Term ends June 1991

Division Executives

1. Division of Aeronomy and Space Physics Chair H.G. lames, Past-Chair, University of Alberta Vice-Chair R.A. Koehler, Secretary-Treasurer, York University

2. Division of Atomic and Molecular Physics G.W.F. Drake, Chair, University of Windsor F.W. Dalby, Past-Chair, University of British Columbia R.L. Brooks, Vice-Chair , Universi ty of Gue lph J.A. Kernahan, Secretary-Treasurer, University of Alberta

3. Canadian Geophysical Union D.E. Smylie, President, York University P. Vanicek, Past-President, University of New Brunswick W.R. Peltier, Vice-President, University of Toronto R.D. Kurtz, Secretary-Treasurer, Ceological Survey of Canada

4. Division of Condensed Matter Physics T. Timusk, Chair, McMaster University G. Wi l l iams, Past-Chair, University of Manitoba H.R. Glyde, Vice-Chair , University of Alberta B.W. Southern, Secretary-Treasurer, University of Manitoba

5. Division of Medical and Biological Physics C.) Thompson , Chair, Montreal Neurological Institute R.M. Henke lman, Past-Chair, Ontario Cancer Institute M. Yaffe, Vice-Chair , Ontario Cancer Institute S.G. Connors , Secretary-Treasurer, Cross Cancer Institute

6. Division of Nuclear Physics H.R. Andrews, Chair, Atomic Energy of Canada E.L. Math ie, Past-Chair, University of Regina G. Roy, Vice-Chair , University of Alberta W.P. A l ford, Secretary-Treasurer, University of Western Ontario

7. Division of Optical Physics R.M. Lees, Chair, University of New Brunswick I.W.Y. Lit, Past-Chair, Wilfrid Laurier University R.A. Lessard, Vice-Chair , Université Laval M. Piché, Secretary-Treasurer, Université Laval

8. Division of Particle Physics R.M. Woloshyn , Chair, TRIUMF R.S Orr , Past-Chair, University of Toronto P. Estabrooks, Vice-Chair , Carleton University D.C. Bailey, Secretary-Treasurer, University of Toronto

9. Division of Physics Education C.G. Deacon, Chair, Memorial University I.K. Dean, Past-Chair, George Brown College Vice-Chai r A.S. Biffi, Secretary-Treasurer, Collège Militaire Royal de St. lean F. Gi rouard , Counc i l l o r , Université de Moncton P. Kirkby, Counc i l l o r , Ontario Hydro L.G. Caron, Counc i l l o r , Université de Sherbrooke

10. Division of Plasma Physics P. Couture , Chair, IREQ, Hydro Québec A. Ng, Past-Chair, University of British Columbia D. McKen, Vice-Chair , Alberta Laser Institute D.M. Vi l leneuve, Secretary-Treasurer, National Research Council

11. Division of Theoretical Physics R. Mann, Chair, University of Waterloo D. Pink, Past-Chair, St. Francis Xavier University Vice-Chair , W. Romo, Secretary-Treasurer, Carleton University

12. Division of Industrial and Applied Physics P. Vincet t , Chair, Xerox Canada B. Paton, Past-Chair, Dalhousie University Vice-Chai r J.F. Bussière, Secretary-Treasurer, National Research Council

13. Division of Surface Science S. Ingrey, Chair, Bell Northern Research R.L. Tapping, Past-Chair, A f . C . L P. Schultz, Vice-Chair , University of Western Ontario T. Jackman, Secretary-Treasurer, National Research Council


1989-1990 COMMITTEES AND REPRESENTATIVES TO OTHER ORGANIZATIONS Standing Committees

1. Science Policy

A.A. Of fenberger (c) C. Do l l i ng L.G. Caron J.A. Ni lson

power to add

2. Editorial Board

C. Dol l ing, Editor M.L. )en to |.C. Cook G. Héber t

3. Publ icat ions

R.W. Nicho l ls (c) D.D. Betts W.R. Datars P.A. Forsyth ). Go t t l i eb R.R. Haer ing G. Herzberg

4. Membersh ip A.). A lcock (c) M.L. Jento

5. Awards

P.A. Egelstaff (c) M.P. Bachynski

Physics in Canada B. Joos J.A. Ni lson R.H. Packwood R. Roy

G.W.F. Drake W. Israel B.K. Jennings B.P. Stoicheff T.W. Johnston B. Margol is A.A. Jones

R. Barber A. Okazaki

C.C. Costain A.A. Ar ro t t

P.R. Wal lace B. Joos J.A. Coxon P. Marmet W.P. A l fo rd M. Piché G. Rostoker

6. Annua l Congress — Program

R.L. A rms t rong (c) G.W.F. Drake D.E. Smylie T. Timusk C.J. Thompson

7. Annua l Congress S.P. Reddy (c) M.L. Jento

H.R. Andrews R.M. Lees R. W o l o s h y n C.G. Deacon P. Cou tu re

- Local C o m m i t t e e

w i t h power to add

G.T. Ewan

R.B. Mann P.S. V incet t S. Ingrey S.P. Reddy M.L. l e n t o

8. Secondary School Physics C o m p e t i t i o n

V.S. Rao plus regional conveners

9. Nomina t i ng L.G. Caron (c) A.A. Of fenberger

R.M. Lees w i t h power to add

10. M e m b e r s h i p Campaign

R.M. Lees (c) R. Keeler L.E. Wa l tham H.A. Buckmaster W. Brouwer |. Vail E.L. Tomusiak F.S. Razavi

J.B. Atk inson P. Kirkby D.K. Hasell P.A. Kalyniak D.B. McLay M. Sut ton A. McGregor R. Marchand

P. Amio t W.R. Ross M. M o r r o w Y.N. Joshi G. Stroink A.C. McMi l l an C. Samson

11. Corpora te Members R.J. Kriegler (c) P.S. V incet t B.A. Paton J.F. Bussière

12. Physics and Society

W. Brouwer (c) w i t h power to add

13. Honorary Advisory Counc i l of Past Presidents


L.G. Caron (c) D.C. Rose J.S. Marshal l A.D. Misener J.L. Kerwin B.W. Sargent G. Herzberg H.E. D u c k w o r t h E.R. Pounder G.M. Vo lko f f L. Katz

P. Lorrain R.E. Bell J.M. Robson H E. Petch M.P. Bachnynski D.D. Betts E.W. Vogt G.G. C lout ie r A.T. Stewart A.H. Mor r i sh R.J.A. Levesque

H.E. lohns R.R. Haer ing P.A. Forsyth C.C. Costain P. Marmet A.R. Crawford B.P. Stoicheff G.C. Hanna A.I. Carswel l J.S. McKee P.A. Egelstaff

15. C o m m i t t e e of R.W. O l le rhead (c) A.F. Ant ippa M. Aub in

E.G. Au ld R.C. Barber G. Bédard R. Bishop C.J. Bland I.G. Cameron I.R. Dagg G.R. Demi l le J.R. De rome R. Dong G. Faucher A. Fi l ion M. Fort in B. Frank F.E. G i rouard

16. Employment Oppor tun i t i es

L.G. Caron (c) M.L. Jento

17. O n Professionalism

P. Kirby (c) K.E. Biretman

Univers i ty Physics Depa

H.R. Glyde I.E. Hardy R.F. Harr is-Lowe M.H. Hawton D. Hunte r T.J. Kennett D.W. Kydon H.E. Lin J.T. MacFarlane B. Mar in ier S.K. Mark R. Monta lbe t t i D.R. Moo rc ro f t D.S. M u r t y S.I.H. Naqvi D.A. Naylor R.W. Nicho l ls

B. Ah lbo rn M.J. Bronski l l

r tment Heads

C.A. Plint M. Plischke M. Press D.H. Rendell L.P. Robertson G. Rubin M. Schlesinger A.M. Simpson A.|. Slavin R.C. Smith P.G. Suther land D.R. Taylor R. Tennyson B.C. Turre l l M.B. Walker I. Zawadski N. Znot inas


F.J. Morgan w i t h power to add

J.D. Prent ice J. Scott E. Svennson G. Tabisz

w i th power to add

14. Tel ler C o m m i t t e e

Members to be appo in ted by the Executive w h e n requ i red

18. To Encourage W o m e n in Physics A.C. McM i l l an (c) D.H. Rendell I. Buck iewicz V. Lister J. Hal l iwel l P. Kalyniak M.A. Jenkins W.J. Megaw R. Petrovich

19. Undergraduate Student Affairs

E.D. Hal lman (c) C. Plume

20. Radiation Regulat ions J. Robins (c) C. Kwok W. Huda J. Scr imger

Ad Hoc Committees

1. Finance Sub C o m m i t t e e of the Executive

A.J. A lcock (c) M.L. l en to 1.E. Hardy w i t h power to add

2. O n Public Awareness of Science & Techno logy

P. Kirkby (c) J.D. Prent ice D.D. Betts G. Rostoker L.G. Caron G. Stroink

Off ic ial CAP Delegates to other Organizations

1. Canadian Commi t t ee for IUPAP A. Cail lé M. Jericho

2. Youth Science Foundat ion

M.A.R. LeBlanc

3. In ternat ional Organ iza t ion for Med ica l Physics

R.L. Clarke M. Cohen

4. Canadian Commiss ion for UNESCO

I. Dean

5. CNC/ ln te rna t iona l Un ion of Crystal lography

B. Powel l

6. Technica l Advisory C o m m i t t e e to A.E.C.L. on Nuclear Fuel Waste Management

M.H.L. Pryce R.J. Uf fen

7. In ternat ional Counc i l on Q u a n t u m Electronics

A.|. A lcock

8. Canadian Chemis t ry & Physics O l y m p i a d

N. Gauth ier

Educational Trust Fund Trustees

D. Betts W.A. Pieczonka G.C. Hanna


CANADIAN UNIVERSITY PHYSICS DEPARTMENTS/ DÉPARTEMENTS DE PHYSIQUE DANS LES UNIVERSITÉS CANADIENNES

INSTITUTION HEAD CHAIR

Acadia University R. Bishop

Brandon University R. Dong

Brock University C.A. Plint

Carleton University J.E. Hardy

Collège Mil i taire Royal de St-Jean A. Filion

Concordia University B. Frank

Dalhousie University A.M. Simpson

École Polytechnique C. Faucher

Lakehead University M.H. Hawton

Laurentian University C. Rubin

McCi l l University S.K. Mark

McMaster University—Physics P.C. Sutherland

—Engineering Physics T.J. Kennett

Memorial University of Newfoundland D.H. Rendell

Mount All ison University J.T. MacFarlane

Queen's University D.R. Taylor

Royal Military College, Kingston R.F. Harris-Lowe

Royal Roads Military College, Victoria M. Press

Saint Francis Xavier University D. Hunter

Saint Mary's University D.S. Murty

Simon Fraser University M. Plischke

Trent University A.). Slavin

University of Alberta H.R. Clyde

University of British Columbia—Physics B.C. Turrell

—Engineering Physics E.G. Auld

University of Calgary C.J. Bland

University of Guelph R.W. Ollerhead

Université Laval G. Bedard

University of Lethbridge D.A. Naylor

University of Manitoba R.C. Barber

Université de Moncton F.E. Girouard

Université de Montréal J.R. Derome

University of New Brunswick—Fredericton C.R. DeMil le

—St. John I.C. Cameron

University of Ottawa R.C. Smith

University of Prince Edward Island H.E. Lin

Université du Québec à Chicout imi M. Fortin

Université du Québec à Montréal I. Zawadski

Université du Québec à Rimouski B. Marinier

Université du Québec à Trois-Rivières A.F. Antippa

University of Regina S.I.H. Naqvi

University of Saskatchewan R. Montalbett i

Université de Sherbrooke M. Aubin

University of Toronto —Physics M.B. Walker

—Engineering Science

University of Victoria L.P. Robertson

University of Water loo I.R. Dagg

University of Western Ontar io D.R. Moorcrof t

University of Windsor M. Schlesinger

University of Winnipeg D.W. Kydon

Wi l f red Laurier University N. Znotinas

York University R.H. Prince

TELEPHONE NO. EX. FAX

(902) 542-

(204) 727-

(416) 688

(613) 788-

(514) 346-

(514) 848-

(902) 424-

(514) 340-

(807) 343-

(705) 675-

(514) 398-

(416) 525-

(416) 525-

(709) 737-

(506) 364-

(613) 545-

(613) 541-

(604) 380-

(902) 867-

(902) 420-

(604) 291

(705) 748-

(403) 492-

(604) 228-

(604) 228-

(403) 220-

(519) 824-

(418) 656-

(403) 329-

(204) 474-

(506) 858-

(514) 343-

(506) 453-

(506) 648-

(613) 564-

(902) 566-

(418) 545-

(514) 987-

(418) 724-

(819) 376-

(306) 585-

(306) 966-

(819) 821-

(416) 978-

•2201 X 290

9695

5550 X 3414

4326

2131

3276

2339

4768

8782

1151 X 2221

6483

9140 X 4263

9140 X 4548

8738

2580

2706

6415

4556

2104/2196

5831

3154

1289

4127

3150

6746

5385

4120

2652

2426

9817

4339

6669

4723

5634

3253

0421

5081

3320

1770

5107

4258/4149

6394

7055

5205

(604) 721-7698

(519) 885-1211 X 2214

(519) 661-3283 X 6444

(519) 253-4232 X 2647

(204) 786-9443

(519) 884-1970

(416) 736-5249

542-4727

726-4573

688-2789

788-4389

848-3494

424-2319

340-4333

343-8023

675-1024

398-3733

528-5030

528-5030

737-4569

364-2262

545-6463

547-3053

380-4513

867-5153

420-5561

748-1246

492-4256

228-5324

228-5324

289-3331

836-9967

656-2040

329-2057

269-8489

858-4541

343-2071

453-4599

564-5014

566-0420

987-3115

966-6400

821-7921

978-5848

721-7715

746-8115

661-2033

973-7075

886-9351

736-5516

POSTAL

E-MAIL CODE

BISHOP@ACADIA B0P 1X0

R7A 6A9

L2S 3A1

[email protected] K1S 5B6

J0J 1R0

BFRANK@CONUI H3G 1M8

PHYS@DALAC (NetNorth/BITNET) B3H 3J5

H3C 3A7

[email protected] P7B 5E1

P3E 2C6

H3A 2T8

SUTHERLA@MCMASTER L8S 4M1

L8S 4M1

DAVIDR@MUN A1B 3X7

A002@MTAM E0A 3C0

K7L 3N6

HARRISLR@RMC K7K 5L0

[email protected] VOS 1B0

[email protected] B2G 1C0

B3H 3C3

USERPLIS@SFU V5A 1S6

K9J 7B8

MHEN@UALTAMTS T6G 2)1

[email protected] V6T 2A6

ASTA@UBCMTSG V6T 1W5

T2N 1N4

PHYSICS@UOGUELPH N1G 2W1

C1K 7P4

[email protected] T1K 3M4

BARBER@UOFMCC R3T 2N2

PHYS@UM E1A 3E9

[email protected] H3C 3J7

[email protected] E3B 5A3

E2L 4L5

K1N 6N5

[email protected] C1A 4P3

G7H 2B1

27724@UQAM H3C 0A2

G5L 3A1

C9A 5H7

S4S 0A2

PHYSICS@SASK S7N 0W0

J1K 2R1

MWALKER@UTORPHYS M5S 1A7

[email protected] V8W 2Y2

[email protected] N2L 3C1

[email protected] N6A 3K7

A29@WINDSOR1 N9B 3P4

UOWDEV@UOFMCC R3B 2E9

N2L 3C5

FS300Q32@YUSOL M3J 1P3


mailto:[email protected]








News / Nouvelles 1989 Royal Society of Canada Awards The Henry Marshall Tory Medal of the Royal Society of Canada has been awarded this year to Dr. Boris P. Stoicheff, F.R.S.C. in recognit ion of his basic work in Raman spectroscopy and of his more recent work in laser physics and laser spectro-scopy. He is credited wi th the discovery of the inverse Raman effect f rom work wi th lasers in his Raman studies, and for the first observation of thermal shear waves in liquids.

Dr. Stoicheff was born in Yugoslavia in 1924 and came to Toronto in 1931. He earned his B.A.Sc. (1947), M.A. (1948) and Ph.D. (1950) f rom the University of Toronto, and joined the National Research Counci l in Ottawa a year later. He returned to the University of Toronto in 1964 where he is currently University Professor.

The Rutherford Medal in Physics has been awarded to Dr. Nathan Isgur, F.R.S.C. Dr. Isgur has made several important contr ibut ions to the field of elementary particle physics, especially to hadron spectroscopy and the quark model, which he has generalized to include excitations of the string connect ing quarks to anti-quarks, leading to very interesting predict ions for the masses and decay modes of so-called hybrid mesons.

Dr. Isgur was born in 1947 in Houston, Texas. He received his B.S. (1968) f rom the California Institute of Technology and his Ph.D. (1974) f rom the University of Toronto. He has been a professor at the University of Toronto since 1982.

The Sir Wi l l iam Dawson Medal of the Royal Society of Canada has been awarded to Dr. Henry G. Thode, F.R.S.C. Dr. Thode, considered one of Canada's most distinguished physical scientists, is best known for his seminal experiments in stable isotope research and nuclear fission. His explorations on the distr ibut ion of the sulphur isotopes have contr ibuted to the fields of chemistry, geology, physics, biochemistry, cosmo-chemistry and environmental science.

From 1961 to 1972, as President and Vice-Chancellor of McMaster University in Hamilton, Ontario, he was concerned wi th the administration of the university — seeking financial resources, planning and developing buildings, and appoint ing staff. Dur ing this period, Dr. Thode resolutely kept his lab-ratory funct ioning, turn ing out world-class research even wi th the administrative demands made on his t ime.

Dr. Thode was born in Dundurn, Saskatchewan, in 1910. He earned his B.Sc. (1930) and M.Sc. (1932) at the University of Saskatchewan, and his Ph.D. (1934) at the University of Chicago. He joined the Department of Chemistry at McMaster University in 1939 where he is currently Professor Emeritus. Dr. Thode has a lengthy record of scholarly and professional activities, including fifteen years (1966-81) as a Director and member of the Executive Committee, Atomic Energy of Canada Ltd. He has received eleven honorary degrees and has publ ished more than 150 papers. Dr. Thode was President of the Royal Society of Canada dur ing 1959-60 and was made a Companion of the Order of Canada in 1967.

CAP Awards at the 1989 Canada-Wide Science Fair The CAP donated three awards of $250 again this year at the Canada-Wide Science Fair for projects best relating to Physics. The Fair was held May 14 to 20, in St. John's Newfoundland.

Melissa Andrew received the award in the Junior category for her project entit led: "La natation de puissance".

Cory Hallam was awarded the prize in the Intermediate Category for his project entit led: "Trusses: A Development Project — Part 2".

Ken Hunt received the award in the Senior Category for a project entit led: "Relativistic Geometrical Distort ions".


AECL Alumnus Named Science Advisor to U.S. President Dr. Allan Bromley, an Ottawa Valley native and former AECL's Chalk River Nuclear Laboratories employee, has been named science advisor to U.S. President George Bush. Dr. Bromley wi l l also head the Off ice of Science and Technology Policy. Born in Westmeath, Ontario, Dr. Bromley earned his bache-lor's and master's degrees at Queen's University, and his doctorate at the University of Rochester, where he became an assistant professor of physics in 1952. He jo ined AECL at Chalk River in 1955, becoming a senior research officer wi th a particular interest in heavy ion research. He jo ined Yale University in 1961.

Dr. Pierre Perron New NRC President On July 25, Prime Minister Brian Mulroney appointed Dr. Pierre O. Perron, then Associate Deputy Minister of Energy, Mines and Resources, as president of NRC for a five-year term.

Dr. Perron is a metallurgist who obtained a Ph.D. f rom Glasgow's University of Strathclyde in 1966 after graduating in metallurgical engineering f rom Laval University.

His field is the application of thermodynamics to metallurgical processes using nuclear techniques. He started work in 1966 as a researcher at AECL's Chalk River Laboratories for two years. Since then, he's pursued a career in research man-agement — at Hydro-Québec, at the Centre de recherche industrielle du Québec, as Associate Deputy Minister of Québec's Department of Energy and Resources and in Ottawa at Energy, Mines and Resources.

Le Dr. Pierre Perron nouveau président du CNRC Le 25 jui l let dernier, le Premier Ministre Brian Mulroney nommait le Dr. Pierre O. Perron, alors sous-ministre délégué du ministère de l'Énergie, des mines et des ressources, président du CNRC pour un mandat de cinq ans.

Le Dr. Perron est métallurgiste de formation. Il a obtenu un doctorat à l 'Université of Strathclyde, à Glasgow, en 1966, après des études en génie métallurgique à l 'Université Laval.

Sa spécialisation porte sur l 'application de la thermodyna-mique aux procédés métallurgiques à l'aide de techniques nucléaires. Il a commencé à travailler en 1966 comme cher-cheur aux Laboratoires de Chalk River de l'EACL pendant deux ans. Il a ensuite poursuivi sa carrière dans la gestion de la recherche: à Hydro-Québec, au Centre de recherche industrielle du Québec, puis comme sous-ministre délégué du ministère de l'Énergie et des Ressources à Québec et, enfin, à Ottawa.

Le CNRC nomme Jacques Martel au poste de directeur de l'Institut de génie des matériaux Le Conseil national de recherches annonce récemment la nominat ion du Dr Jacques G. Martel au poste de directeur de l'Institut de génie des matériaux (IGM) du CNRC.

Le Dr Martel est d ip lômé en génie physique de l'École polytechnique de Montréal. Il est t i tutlaire d 'un doctorat en génie nucléaire qu' i l a obtenu au Massachusetts Institute of Technology (M.I.T.) en 1971.

Le Dr Martel succède à M. Georges Bata, directeur-fondateur de cet institut du CNRC qui a maintenant 10 années d'exis-tence. M. Bata maintiendra ses liens avec le CNRC comme conseiller.


Canadian Physicists Physiciens canadiens AT YORK UNIVERSITY . . . G.R. Hébert is on a six-month sabbatical. However, he still does the work of Assistant editor of the C.J.P./J.C.P. and Book-Review Editor of Physics in Canada/La Physique au Canada.

One of our welcomed visitors at York's Physics department dur ing July and August of 1989 was Dr. John Humberston, f rom University College London. His work, as well as that of several other short-term visitors who come to collaborate with physicists at York, would seem to indicate that York is fast becoming a mecca for positron-coll ision physics.

The department was indeed pleased to see Dr. Les Parcell spend several weeks with the atomic and molecular Physicists dur ing the summer months.

Al Stauffer, who left his stint of duty as Chairman of York University Senate on June 30,1989, is currently spending part of his full-year sabbatical at JILA.

Dr. D. Smylie tells us that "people can now join the Canadian Geophysical Union directly (for $25.00) or become a Founder (for $100.00), even though one can join through the C.A.P. The C.G.U. is now broadening its interests to include all of the Geophysical sciences, much like the A.G.U.! ' One should note that D.E. Smylie is currently president of the Union Géophysique Canadienne/Canadian Geophysical Union.

What was known for many years as York's "Centre for Research in Experimental Space Science, (CRESS)" has been officially changed to CENTRE FOR RESEARCH IN EARTH AND SPACE SCIENCE, (CRESS). Similarly, York's Senate also changed the name of the corresponding programme to: THE GRADUATE PROGRAMME IN EARTH AND SPACE SCIENCE. Thus York wi l l have programmes in CRESS that should be recognized as an M.Sc. or a Ph.D. degree in Earth and Space Science.

The Senate of York University also approved, in June, 1989, a new Faculty of Science B.Sc. programme in SPACE AND COMMUNICATIONS SCIENCES commencing in the fall of 1989. The graduates from this programme should be well prepared for careers with companies and research institutions in Canada's growing space industries. R. Prince, Chairman of the York's Physics Department is currently the Student Advisor for this programme.

CAP Publications and Membership Certificate The Directory of Employers of Physicists conta ins deta i led in fo rmat ion o n 140 non-academic employers of physicists in Canada. As wel l as the a lphabet ical l ist ing, employers are also l isted by reg ion and by areas of activi ty.

The Directory of Canadian Physicists, second ed i t ion , lists some 1500 physicists w i t h their areas of expert ise. It conta ins about 500 new listings and updated in fo rma t ion on indiv iduals whose names ap-peared in the first ed i t ion . It is available on diskette in ASCII format .

A membership certif icate (sample on ins ide back cover) is n o w available to fu l l members in g o o d standing. Please comp le te the i n fo rma t ion on the o rder fo rm, i nc lud ing your membersh ip number , and re tu rn w i t h your cheque. Please a l low 6-8 weeks for del ivery.

Publications de l'ACP et certificat de membre Le Répertoire des employeurs de physiciens c o m p r e n d des renseigne-ments détai l lés sur env i rons 140 emp loyeurs des mi l l ieux non-universitaires au Canada. En plus de l ' énuméra t ion par o rd re a lphabé-t ique, ce recuei l cont ien t une répar t i t ion par rég ion ainsi q u ' u n e énuméra t i on par sujets d'act ivi tés.

Le Répertoire des physiciens canadiens, deux ième éd i t ion , con t ien t les noms, adresses et champs d 'act iv i té d 'env i ron 1500 physiciens, que lques 500 noms y f igurant pour la p remiè re fois. D'ai l leurs, les renseignements sur un grand n o m b r e de personnes ont été mis-à- jour . Le réper to i re est d ispon ib le sur d isquet te en format ASCII.

Les membres t i tu laires en règle peuvent maintenant se p rocu re r un certif icat de membre (voir l 'exempla i re sur la couver tu re intér ieure). Veui l lez comp le te r et nous re tourner le fo rmu la i re avec vot re chèque. Vous recevrez vo t re cert i f icat dans env i ron 6 à 8 semaines.

ORDER FORM — BON DE COMMANDE D i r e c t o r y o f E m p l o y e r s o f P h y s i c i s t s / R é p e r t o i r e d e s e m p l o y e u r s d e p h y s i c i e n s

P r i c e / P r i x : $10 C A P m e m b e r s / m e m b r e s d e l ' A C P

$25 n o n - m e m b e r s / n o n - m e m b r e s

$50 i n s t i t u t i o n s

D i r e c t o r y o f C a n a d i a n P h y s i c i s t s / R é p e r t o i r e d e s p h y s i c i e n s c a n a d i e n s

S e c o n d e d i t i o n / D e u x i è m e é d i t i o n . O n diskette o n l y / s u r disquette s e u l e m e n t

P r i c e / P r i x : $15

M e m b e r s h i p C e r t i f i c a t e / C e r t i f i c a t d e m e m b r e

P r i c e / P r i x : $25

I w i s h t o p u r c h a s e / j e d é s i r e a c h e t e r

c o p i e s o f / d e _ _ _ _ _

c o p i e s o f / d e

A m e m b e r s h i p c e r t i f i c a t e / U n c e r t i f i c a t d e m e m b r e

T o t a l e n c l o s e d / T o t a l c i - i n c l u s

N a m e t o a p p e a r o n c e r t i f i c a t e

N o m à i n s c r i r e su r le c e r t i f i c a t _

@

@

@

M e m b e r s h i p n o . / n u m é r o d e m e m b r e

Address adresse

Postal code / code postal

Please m a k e c h e q u e p a y a b l e t o / V e u i l l e z l i b e l l e r v o t r e c h è q u e à:

C a n a d i a n Assoc ia t ion o f Phys ic is ts /Assoc ia t ion c a n a d i e n n e des physic iens

C a n a d i a n A s s o c i a t i o n o f Phys ic i s ts

A s s o c i a t i o n c a n a d i e n n e d e s p h y s i c i e n s

151 S la te r , S u i t e 903

O t t a w a , O n t a r i o

K1P 5 H 3


CAP REPRESENTATIVES TO OTHER ORGANIZATIONS LES REPRESENTANTS DE l'ACP A DES ORGANISMES

Members of the CAP are invited to submit names of persons who could be considered to represent CAP in other organizations. Les membres de l'ACP sont invités à soumettre le nom de personnes qui seraient susceptibles de représenter l'ACP au sein d'autres organismes.

I, the undersigned, suggest that Je, sousigné, propose que

Name nom

Address adresse

be considered for selection as Official CAP Delegate or nominee to soit considéré pour le poste de représentant officiel de l'ACP ou comme candidat proposé à l'organisme suivant

(Name of organization) (nom de l'organisme)

Signature

Name and Address of Nominator Nom et adresse du proposeur

Please include a c.v. of the individual and evidence that he/she would accept the nomination if selected. Veuillez joindre le curr iculum vitae de la personne ainsi qu'une lettre indiquant son assentiment à cette candidature.

In order for your candidate to be considered, this form must be returned by November 1, 1989 to: Cette formule doit être retournée au plus tard le 1er novembre 1989 au :

Chairman Président CAP Nominating Committee Comité des candidatures c/o Canadian Association of Physicists a/s Association canadienne des physiciens 151 Slater Street, Suite 903 151, rue Slater, Suite 903 Ottawa, Ontario Ottawa (Ontario) K1P5H3 K1P5H3

or to a member of Counci l (The names and affiliation of all members of the 1989/90 Council are listed on page 162 of this issue of Physics in Canada). ou à un membre du Conseil (la liste des membres du Conseil figure à la page 162 de ce numéro de la Physique au Canada).


Books Received/Livres reçus The following books have been received for review. Readers are invited to write reviews of books of interest to them. Books may be requested from the book review editor G.R.Hébert: BITNET:"PHYSCANQYUSOL" or at Department of Physics, York University, 4700 Keele St., North York, Ontario, M3J 1P3. Tel: 1-416-736-2100 ext. 3837.

Note: All prices listed below are in U.S. $ unless otherwise specified.

* * * * * * * * * * * * * * *

00 General

THE ATOMIC SCIENTISTS, A Biographical History, by Henry A. Boorse, Lloyd Motz & Jefferson Hane Weaver, John Wiley & Sons, 1989, pp viii+472. ISBN 0-471-504-55-6; QC773.B66. Price: $ 27.95 he.

GAUGE FIELD THEORIES, by Stefan Pokorski, Cambridge University Press, 1987, pp xiii+394. ISBN 0-521-368-46-4; QC793.3.F5P65. Price: $ 34.50 pbk.

MATHEMATICAL METHODS IN CHEMISTRY AND PHYSICS, by Michael E. Starzak, Plenum Press, 1989, pp x+651. ISBN 0-306-43066-5; QC39.3.M3S73. Price: $ 69.50 he.

NOISE IN NONLINEAR DYNAMICAL SYSTEMS, vol. 1, Theory of Continuous Fokker-Planck Systems, edited by Frank Moss & P.V.E. McClintock, Cambridge University Press, 1989, pp xvi+353. ISBN 0-521-35228-2; QC6.4.F58N64. Price: $ 85.00 he.

NOISE IN NONLINEAR DYNAMICAL SYSTEMS, vol. 2, Theory of Noise Induced Processes in Special Applications, edited by Frank Moss & P.V.E. McClintock, Cambridge University Press, 1989, pp xviii+388. ISBN 0-521-352-29-0; QC6.4.F58N64. Price: $ 85.00 he.

NOISE IN NONLINEAR DYNAMICAL SYSTEMS, vol. 3, Experi-ments and Simulations, edited by Frank Moss & P.V.E. McClintock, Cambridge University Press, 1989, pp xi + 278. ISBN 0-521-352-65-7; QC6.4.F58N64. Price: $ 75.00 he.

NONPERTURBATIVE QUANTUM FIELD THEORY, edited by G.'t Hooft, A. Jaffe, G. Mack, P.K. Mitter and R. Stora, Plenum Press, 1988, pp ix+603. ISBN 0-306-43027-4; QC17 4.45.A1N37. Price: $ 110.00 he.

OPTICAL TECHNIQUES FOR INDUSTRIAL INSPECTION, by P. Cielo, Academic Press, Inc., 1988, pp xii+606. ISBN 0 12-174655-0; TS156.2.C55. Price: $ 74.50 he.

THE STORY OF PHYSICS, by Lloyd Motz and Jefferson Hane Weaver, Plenum Press, 1989, pp xiii+412. ISBN 0-306-43076-2; QC21.2.M65. Price: 24.50 he.

2 0 NUCLEAR PHYSICS

ADVANCES IN NUCLEAR PHYSICS, Vol. 19, edited by J.W. Negele and Erich Vogt, Plenum Press, 1989, pp xvi+380 ISBN 0-306-43046-0; QC173.A2545. Price: $ 72.50 he.

MAGNETIC SCATTERING, by Malcom F. Collins, Oxford University Press, 1989, pp xi+188. ISBN 0-19-504600-5 QC765.C65. Price: Can. $ 69.95, he.

NEUTRON OPTICS, A Introduction to the Theory of Neu-tron Optical Phenomena and Their Application, by Var-ley F. Sears, Oxford University Press, 1989, pp x+317 ISBN 0-19-504601-3; QC793.5.N4628S43. Price: Can $ 84.00, pb.

NEW ASPECTS OF HIGH-ENERGY PROTON-PROTON COLLISIONS, edited by A. Ali, Plenum Press, 1988, pp xii+434. ISBN 0-306-43106-8; QC793.5.P728154. Price: $ 95.00hc.

RF PLASMA HEATING IN TOROIDAL FUSION DEVICES, by V.E. Golanty S V.I. Fedorov, transi, by Donald H. McNeill, Consultants Bureau, 1989, pp viii+194. ISBN 0-306-11-021-0; QC718.5.H5G6513. Price: $ 85.00 he.

30 ATOMIC AND MOLECULAR PHYSICS

PHOTON-ATOM INTERACTIONS, by Mitchel Weissbluth, Aca-demic Press, 1989, pp xiii+407. ISBN 0-12743660-X; QC794.8P4W45. Price: $ 69.50 he.

THE STRUCTURE OF SMALL MOLECULES AND IONS, edited by Ron Naaman and Zeev Vager, Plenum Press, 1988, xi+351 ISBN 0-306-43016-9; QD461.I65. Price: $ 75.00 he.

4 0 FUNDAMENTAL AREAS OF PHENOMENOLOGY

NONLINEAR FIBER OPTICS, by Govind P. Agrawal, Academ-ic Press, Inc., 1989, pp xii+342. ISBN 0-12-045140-9; QC448.A38. Price: $ 39.95 he.

SURFACE ACOUSTIC WAVE DEVICES AND THEIR SIGNAL PROCES-SING APPLICATIONS, by Colin Campbell, Academic Press, 1989, pp xiv+470. ISBN 0-12-157345-1; TK5981.C35. Price: $ 59.95 he.

50 FLUIDS, PLASMAS, AND ELECTRICAL DISCHARGES

ELECTRON-EXCITED MOLECULES IN NONEQUILIBRIUM PLASMA, Proceedings of the Lebedev Physics Institute, Academy of Sciences of the USSR, vol. 179, suppl. vol. 2, e-dited by N.N. Sobolev, transi, by Kevin S. Hendzel, Nova Science Publ., 1989, pp x+272. ISBN 0-941743-25-X. Price $ 79.00 he.

THE LIQUID STATE AND ITS ELECTRICAL PROPERTIES, edit-ed by E.E. Kunhardt, L.G. Christophorou, & L.H. Lues-sen, Plenum Press, 1987, pp xii+573. ISBN 0-306-4314-5-9; QC14 5.4.E455N37. Price: $ 110.00 he.

REVIEWS OF PLASMA PHYSICS, vol. 14, edited by B. B. Zkadomtsev, transi, by J.G. Adashko, Consultants Bur-eau, 1989, pp vi+252. ISBN 0-306-11004-0; QC718.V63. Price: $ 85.00 he.

60 CONDENSED MATTER: STRUCTURE, MECHANICAL, AND THERMAL PROPERTIES

THE METALLIC BOND AND THE STRUCTURE OF METALS, by V.K. Grigorovich, transi, by A1 Peabody, Nova Sci-ence Publ., 1989, pp x+311. ISBN 0-941743-50-0; QD4 61.M57713. Price $ 78.00 he.

SUPERALLOYS, SUPERCOMPOSITES AND BUPERCERAMICS edit-ed by John K. Tien S Thomas Caulfield, Academic Press Inc., 1989, ppxxvii+755. ISBN 0-12-690845-1;TA485.S95 Price: $ 129.95 he.

70 CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRI-CAL, MAGNETIC, AND OPTICAL PROPERTIES

ELECTRON PROCESSES IN MIS-STRUCTURE MEMORIES, Proceed, ings of the Lebedev Physics Institute, Academy of Sci-ences of the USSR, vol. 184, edited by A.F.Plotnikov, transi, by Paul Makinen, Nova Science Publ., 1989, pp vi+227. ISBN 0-9417-43-53-5. Price $ 77.00 he.

STUDIES OF HIGH TEMPERATURE SUPERCONDUCTORS, edited by Anant Narlikar, vol 1, Nova Science Publ., 1989, pp xiv+381. ISBN 0-941743-54-3. Price: $ 72.00 he.

STUDIES OF HIGH TEMPERATURE SUPERCONDUCTORS, edited by Anant Narlikar, vol 2, Nova Science Publ., 1989, pp xiv+381. ISBN 0-941743-55-1. Price: $ 72.00 he.

80 CROSS-DISCIPLINARY PHYSCIS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

CHEMICAL SENSING WITH SOLID STATE DEVICES, by Marc J. Madou and S. Roy Morrison, Academic Press, Inc., 1989 pp xv+556. ISBN 0-12-464965-3; TP159.C46M33. Price: $ 89.50 he.

MONTE CARLO TRANSPORT OF ELECTRONS AND PHOTONS, edit-ed by Theodore M. Jenkins, Walter R. Nelson, and Ales-


sandro Rindi, Plenum Press, 1988, pp xviii+638. ISBN 0-306-43099-1; QC176.8.E41537. Price: $ 115.00 he.

TERRESTRIAL SPACE RADIATION AND ITS BIOLOGICAL EF-FECTS, Proceedings of a NATO Advanced Study Institute on Terrestrial Radiation ..., held in Corfu, Greece, in 1987, edited by Percival D. McCormack, Charles E. Swenberg & Horst Bucker, Plenum Press, 1988, pp x+864 ISBN 0-306-43020-7; QH652.A1N36. Price: $ 129.50

90 GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

SELECTED PAPERS, vol. 1: STELLAR STRUCTURE AND STEL-LAR ATMOSPHERES, by S. Chandrasekhar, The University of Chicago Press, 1989, pp xiv+515. ISBN 0-226-10089-8; QB808.C47. Price: $ 74.95 he.; $ 29.95 pbk.

Book Reviews Critiques des livres ADVANCES IN ATOMIC AND MOLECULAR PHYSICS, vol. 25, edited by Sir David Bates and Benjamin Bederson, Aca-demic Press, Inc., 1988, pp xv+559, ISBN 0-12-003-825-0. Price: $ 99.50 he.

The latest volume in this well respected series is a festschrift on the occasion of the 60th birthday of Alexander Dalgarno, Philips Professor of Astronomy at Harvard University. There are twenty-one articles in this volume written by former students and co-workers of Prof. Dalgarno. The range of topics is very wide, reflecting the immense variety of research interests of this man who has been one of the outstanding the-orists in the field of Atomic and Molecular Physics for over forty years. Three of the articles review Prof. Dalgarno's contributions in the fields of Atom-ic and Molecular Physics, Aeronomy and Astrophysics. The remaining articles reflect the research interests of the individual authors and are mainly in the field ofAtomic and Molecular Physics with some applications to Astronomy dealing with interstellar molecules. Most of the articles are of a theoretical nature, re-flecting Prof. Dalgarno's own work, but a few concen-trate on experimental work such as dipole polariza-ility measurements, ion-molecule reactions and atom-atom or ion-atom collisions. The remaining articles cover atomic processes in plasmas, spectral line sha-pes, and various methods for the calculation of bound state properties or scattering processes in atomic or molecular systems including some work on relativistic methods.

Because the number of articles in this volume are las ger than in the other volumes in this series, the ar-ticles are shorter than usual and hence tend to give an overview of the subject rather than an exhaustive review. Some also contain recent work of a more spe-cific nature. However to have such a large collection of articles written by many of the leading figures in the field is a distinct advantage. I have found the book useful as a quick reference on a particular top-ic as well as providing an up-to-date summary of the progress in the field. Those of us who have the pri-vilege of knowing Prof. Dalgarno welcome this fitting tribute to an outstanding researcher and will find this volume a valuable addition to our library.

Allan D. Stauffer Department of Physics York University

THE "DELFIN" LASER THERMONUCLEAR INSTALLATION: OPER-ATIONAL COMPLEX AND FUTURE DIRECTIONS, Proceedings of the Lebedev Physics Institute, Vol. 178, Academy of the Sciences of the USSR, edited by G.V. Sklizkov, transi, by Kevin S. Hendzel, Nova Science Publishers, 1988, pp viii+292. ISBN 0-941743-22-5; QC1.A4114. Price: $ 92.00 (U.S.& Ca.), $ 110.00 elsewhere).

This volume contains eight papers concerning various details of the design and operations of the Russian inertial confinement fusion (ICF) installation named Dolfin. This is the first comprehensive review of the

installation since its inception. This review gives the overall design philosophy and physical bases for such philosophy, detailed engineering and system de-signs, as well as individual component design and per formance.

Since the inception of ICF, the Russian approach has been using the concept of ablative imploding targets with nanoseconds pulses, while the US approach ori-ginally concentrated on using the exploding pusher' with subnanosecond pulses. Moreover, the Russians have been using multilayer targets for experimenta-tion from the start, whereas the Western laboratories switched to multilayer targets more recently. In this book, various difficulties encountered in the initial stages of the development of both approaches are dis-cussed.

The first paper contains a brief survey of the ICF research conducted at the Lebedev Institute. It also discusses the design philosophy and overall system considerations. The second paper presents the study on achieving optimum target irradiation. The third paper investigates the means of achieving radiation with a given spatial coherence. The fourth paper dis-cusses the need of suppressing target reflected radi-ation, and the usage and design of Faraday rotators for such purposes. The next paper studies the influ-uence of the nonradiative transition rates in Nd la-ser glasses and crystals. This is important because the nonradiative relaxation rates among the pump and lasing transitions largely determine the energy capa-bilities of the laser system, the spectral composi-tions and radiation kinetics. It is found that such relaxation rates are very fast, of the order of pico-seconds. The next paper analyses the requirements im-posed on ultra-high-speed multiple-image photography systems, and describes the design of the laser plasma and shock wave optical diagnostic systems. The seven-th paper describes remote optical target position mon-itoring systems. The last paper describes an automa-ed data collection and processing system for plasma-corona diagnostics. Experimental results for glass shell targets are given.

This book is rich in information and detail, about the "Dolfin" ICF system. It fills many details of earlier papers from the Lebedev Institute on its ICF experi-mental results. Some important topics such as target irradiation uniformity, multi-beam energy balance and timing, and target dynamics, are not discussed in any detail. The references cited are dated only up to the 1983-84 years. Thus, this it is not the most recent report of the Dolfin' system. Western' references are sparsely cited and only up to 1982. Nonetheless, this volume is a useful addition to the literature of ICF.

K.K. Lee Optical Group Perkin-Elmer

FUNDAMENTALS OF MOLECULAR SPECTROSCOPY, by Walter S. Struve, John Wiley & Sons Inc., 1989, pp xii+379. ISBN 0-471-85424-7; QC454.M6S87. Price: $ 49.95, he.

This book is just what the preface describes: a con-cise introduction to the spectroscopy of atoms and molecules at the graduate level. Most of the emphasis is on the rotation-vibration and electronic spectra of diatomic and polyatomic molecules, but the book starts with a solid introduction to atomic spectra and ends with three chapters (12 5 pages) on lasers and nonlinear optics. The first of these is a good introduction for readers with no previous knowledge of lasers. The theoretical sections of the book re-quires a thorough background in quantum mechanics.

It is not surprising, and not to be disparaged, that most of the theoretical material is standard fare. This, after all, is a mature subject. There is also a healthy emphasis on experimental spectra and their interpretation. Nevertheless, it is clear that this is not really a book on how to analyse spectra. There is little coverage of the traditional methods, e.g. combination differences, and none of the modern tech-niques involving the optimization of model Hamilton-ians.


This book is not competitor of the Herzberg volumes. Its theoretical content is considerably deeper and more extensive, but its description of real spectra and their analysis is much shallower. This is simply the nature of the compromise the author has had to make in a book of 380 pages.

Anyone who has loved spectroscopy long and well will find the book incomplete in at least minor ways. For example, lambda doubling is mentioned as resulting from an interaction of rotational and electronic an-gular momenta, but nothing more is said about it. In the discussion of breakdown of the Born Oppenheimer approximation, the term diabatic states is not men-tioned. This may well be a considered omission, as the term has been used ambiguously, but diabatic is so common a term that it should be explained. In the 16 page chapter on line shapes and intensities there is only the most casual mention of collision broaden-ing. Honl-London factors do not seem to be mentioned anywhere. Franck-Condon factors are given only half a page in connection with diatomic molecules. Neither they nor nuclear spin statistics are mentioned for polyatomic molecules.

Each chapter ends with a set of references and a few problems. The references are appropriate, often clas-sics, but only a small percent are dated in the nine-teen eighties. The problems are generally realistic and appropriate in subject and difficulty.

Is this book really necessary? It is very similar to Jeffrey I. Steinfeld's Molecules and Radiation (M.I. T.) Press, 1974) in its intended audience, contents, and level of treatment, though, of course, there are many differences in emphasis.

No one planning a first graduate course on molecular spectroscopy should choose one of these books before examining the other.

In a book on fundamentals, there must be a division of emphasis between basics and applications which can not please everyone. A reader who does not expect too much of either may decide that Struve has made his division wisely.

Tucker Carrington C.R.E.S.S. York University

GROUP STRUCTURE OF GUAGE THEORIES, by L. O'Raifear-taigh, Cambridge Monographs on Mathematical Physics, Cambridge University Press, 1988, pp ix+172. ISBN 0-521-34785-8; QC793.3.F5069. Price: 13.95 pbk.

The utility of group theoretic methods and techniques in physics is virtually impossible to underestimate. As a consequence there now exist a rather large num-ber of textbooks on this subject which deal with the various aspects of this rich mathematical jewel.

With this small book, 0 1 Raifeartaigh has brightly pol-ished yet another of its facets. Dividing the subject into two distinct parts, he clearly outlines both the relevant mathematical tools in part I and then fol-lows up with their application to gauge theories in particle physics in part II. Economy of language is neatly used without sacrificing any essential mathe-matical or physical details. Indeed, he expends ad-ditional effort to clarify obscure points in other books and to clearly elucidate the distinction be-tween fact and folklore in the subject.

With useful exercises at the end of each chapter and with an extensive glossary appearing at the end of the text, this book would be a useful addition to any particle physicist's library. Previously only a hard-back edition of this book (reviewed in an earlier is-sue of Physics in Canada by Dwight Vincent) had been available. The reduction in price permitted by the softback edition makes this book an exceptional bar-gain.

Robert Mann Department of Physics University of Waterloo

MICROSOFT QUICKBASIC FOR SCIENTISTS, by James W. Co-oper, John Wiley & Sons, 1988, pp xvii+281. ISBN 0-471-61301-0; QA76.73.B3C665. Price: $ 29.95 pbk.

The Microsoft QuickBASIC for Scientists also bears the secondary title: A Guide to Writing Better Pro-grams. QuickBASIC (QB) is a version of BASIC that is actually a compiler i.e.it is a version of BASIC that compiles programs and runs them, hence1 an inherently faster running "BASIC". QB is NOT an interpretive lan guage! There are no line numbers in Q.B., thus the u-sual BASIC "decision" statements that refer to line numbers cannot be used. A more extensive use of logi-cal " IF-THEN-ELSE1 and WHILE-WEND' etc. statements have to be used instead. The author makes a great to-do regarding this feature although, in fact, I was reminded of the fable: The Fox Who Lost his Tail when I read the emphasized exposition extolling the "num-berless" feature of this version of BASIC.

The text leads the reader in a clear logical fashion through the basics of BASIC programming in the first 10 chapters. These include topics of: Elements of QB, Decision Making, Strings and Functions, Using Arrays and Files, Editing and Compilation, Debugging, Sub-routines and Subprograms, Keyboard and Displays, and Memory Handling in QB. Chapters 12 & 13 deal with QB Screen Graphics and Printer Control. DOS, and Files & DOS are treated in the next two chapters. The multi-topic Chapters 14 to 23 discuss the use of the Mouse, Sorting Procedures, Matrix Algebra,Fast Fourier Trans-forms, Structural Programming, Plotting and Display Techniques, and Assembly Language Programming (mainly for the 8088 Microprocessor). Here and there through-out the text are listed a number of useful programs; e.g. "Reading a Record File Program", "Subprogram MOU-SE Which Passes and Returns up to 4 Arguments"; and "The Complex Fast Fourier Transform". A fourteen-page index enhances the value of the text.

In all, a useful book for both novice microprocessor user and "BASIC" programmers alike who want to make use of a faster, compiled, BASIC programmer language.

Gérard R. Hébert Department of Physics York University

SIGNAL ANALYSIS AND ESTIMATION, An Introduction, by Ronald L. Fante, John Wiley & Sons, 1988, pp xiv+ 448. ISBN 0-471-62425-X; TK5102.5.F36. Price: U.S.$ 44.95.

This book deals with a subject matter that has grown in popularity since the introduction of the computer in the processing of signals such as acoustical, e-lectrical, geophysical and optical signals. Spectral analysis and estimation techniques are involved in diverse applications such as radar, computer-aided tomography, remote sensing and geophysical explora-tion.

This book is divided into two roughly equal parts: Part I deals with Deterministic Signals, and Part II with Random Signals. Part I introduces Fourier series and the Fourier transform for continuous signals. Dis-crete signals and the discrete Fourier transform are then considered, and the Fast Fourier Transform (FFT) is explained. This section of the book also deals with practical problems such as the sampling, window-ing and aliasing of data and the calculation of FFTs. Part II (Random Signals) introduces the basic con-cepts of probability theory needed to characterize and analyse random signals. Traditional and modern techniques of spectral analysis and spectral estima-mation are then considered, including techniques such as the Kalman filter and the Maximum Entropy Method.

This book is designed for a 12-week university course It requires no mathematical knowledge beyond first year university calculus, and includes a generous set of problems designed to illustrate applications which are not included in the book. The text is kept at a level that allows the student to understand the ba-sics of the subject matter without overwhelming him with details, and allows the inquisitive mind to ab-sorb more advanced expositions.


This is also a book for the physicist or engineer who needs to understand and apply the techniques of spec-tral analysis and spectral estimation. It is a prac-tical book which includes a discussion of the pit-falls likely to be encountered when using the tech-ques. Overall, this book is a very good introduction to signal analysis and estimation.

Pierre A. Millette Bell-Northern Research

STATISTICAL MECHANICS OF MAGNETICALLY ORDERED SYSTEMS by Yu. A. Izyumov & Yu. N. Skryabin, transi, by Roger Cooke, Consultants Bureau (Plenum Publ. Corp.), 1988, pp xii+295. ISBN 0-306-11015-6; QC762.19513. Price: $ 85.00, he.

This is an advanced treatise on magnetism with three major topics: Heisenberg, Hubbard and s-d models. The methods discussed include diagrammatic technique for spin operators, path integration, and techniques for exact solutions. A wide and interesting range of to-pics are covered: a diagrammatic technique for Hub-bard operators in the discussion of the microscopic theory of phase transition, the Kondo effect, the derivation of the renormalization group for n-vector models, the static limit of the coherent potential approximation in the treatment of the Hubbard model by path integral, and low dimensional magnetic sys-tems. The chapter on two-dimensional systems are es-pecially well written, with sections on the exact sol ution of the Ising model, the Berezinskii-Koster-litz-Thouless vortex unbinding transition in the classical XY model and the instanton solution in the classical Heisenberg model. The last chapter is devoted to one-dimensional exactly solvable systems. The Bethe an-satz and the quantum method of the inverse scattering problem are discussed together with applications to different models of magnetism.

In many ways, this book complements the classic trea-tise of Mattis in that a short but more advanced tre-atment of many topics of current interest are succint ly discussed. The combination of techniques, such as the application of renormalization group analysis in the treatment of topological excitations, also pro-vides a good example for graduate students and resear chers alike in the learning of some of the most re-cent developments in magnetism. It can be used as a reference book, in conjunction with the books by Stan-ley, and by Amit et al. for a rigorous course in cri-tical phenomena. Field theorists may also find it use ful for insights into the some of the recent exciting developments in condensed matter physics, as many of the techniques originally come from there. The reader should, however, be warned that the language familiar to the field theorist is avoided in this book. The last chapter is a good attempt to introduce readers to the fast and turbulently developing areas of math-ematical physics of exact solutions, without intimi-dating mathematics.

As with many advanced books, this book does not cover some of the topics that one wishes to read about. The lack of an index makes it hard to use as a reference, but this shortcoming is partially overcome by the huge list of references, (177 of them with the latest in 1985). Notwithstanding these minor criticisms,this book is highly recommended to serious students in the theory of magnetism. Libraries too should have this book available for general reference.

K.Y. Szeto Dept. of Physics York University

SUPERLUMINAL RADIO SOURCES, Proceedings of a Workshop in Honor of Professor Marshall H. Cohen, held at Big Bear Solar Observatory, California, October 28 - 30, 1986, edited by J. Anton Zensus and Timothy J. Pear-son, Cambridge University Press, 1987; pp xv+361. ISBN 0-521-34560-X. Price: $ 49.50.

In the fall of 1986 a workshop on "Superluminal Radio Sources" was held to celebrate the sixtieth birthday of Professor Marshall H. Cohen of Caltech, a pioneer in the technique of Very Long Baseline Interferometry

(VLBI). This book contains a summary of the proceed-ings of that Workshop. Each chapter (of which there are thirty-nine, written by conference participants) provides a brief, informal review of some aspect of the study of superluminal radio sources.

The first two chapters provide an introduction and overview. VLBI observations of the milliarcsecond-scale structure of bright radio sources were first made in 1967 by Canadian and American teams of radio astronomers. Contemporaneous theoretical work sug-gested that the rapid radio brightness fluctuations seen in some compact sources might require expansion at relativistic velocities. With VLBI resolution, which provides a few light years linear resolution at cosmological distances, this expansion could produce detectable structural changes over time scales of a few months to years.

In fact, for an object moving relativistically at an angle near to the line of sight, apparent transverse velocities much greater than the speed of light are possible. The discovery in the early 1970s that some radio sources do appear to expand faster than the speed of light was a great triumph for VLBI.

The contents of this book deal with the many issues which arise because of the superluminal phenomenon. For instance, what would superluminal sources look like if they were not relativistically beamed towards us? Might they be extended steep-spectrum radio soup ces seen from a perspective which enhances their in-trinsically faint core emission?

Much of the book discusses particular superluminal radio sources. Also, non-VLBI data (such as lower re-solution optical spectroscopy, and radio and optical polarimetry) thought to be relevant to the interpret-ation of superluminal sources are discussed. The fin-al chapters attempt to synthesis preceding chapters and to provide a theoretical framework.

The editors have made this book especially useful to graduate students in astronomy, and others interested in becoming acquainted with developments in thisfield field, by providing an extensive bibliography listing all books and articles referred to in the text, and complete subject and astronomical object indices. For workers in the field, acquaintance with this book is a necessity!

Raymond Rusk Defence Research Establ. Pacific Electromagnetics Section, Victoria, B.C.

SUPERMASSIVE BLACK HOLES, by Minas Kafatos, edit., Cambridge University Press, 1988, pp 382. ISBN 0-521-34246-5. Price: $ 54.50.

This book is a collection of invited and contributed papers on supermassive black holes (SBHs) presented at the Third George Mason Fall Workshop in Astrophy-sics in October 1986. McKee's excellent overview of the conference in the final paper divides the discus-sion of SBHs into: evidence for their existence, for-mation and evolution, and how they "shine."

A large fraction of the papers are devoted to the weak observational evidence in favour of the exist-ence of SBHs. (Most authors readily admit that the observational evidence for SBHs is not as convincing as the evidence for stellar mass black holes in bin-ary systems, where Kepler's Laws apply directly.) Sharply-peaked velocity dispersion profiles have been found in the centres of a few local galaxies consist-ent with the presence of a "dark" point mass of at least 1-10 million solar masses. As well, weak H-al-pha emission has been uncovered in a number of nearby galaxies with broad profiles reminiscent of profiles found in the spectra of quasars and active galactic nuclei (AGNs).

Most of the observational discussion is centred on quasars and AGNs, however. Rapid optical and X-ray continuum variability (requiring high energy conver-sion efficiencies), "flat" spectral energy distribu-tions (often from radio through gamma-ray energies) extreme UV — soft X-ray "bumps" (suggesting thermal


emission from an accretion disk), all point to a com-pact, supermassive "central engine" in quasars at least 10-100 times more massive than in the local galaxies.

While theoreticians provide the strongest arguments in favour of SBHs in this book, several papers warn that a number of fundamental problems associated with SBHs (e.g. accretion disk stability) have yet to be solved. There are some brief discussions of the ori-gin and evolution of SBHs in galactic nuclei. A SBH cannot form from the core collapse of a "normal" gal-actic nucleus, although it may form from a dense nu-clear star cluster, or a "seed" hole that grows by accretion from the formation epoch. Finally, there are a number of papers that speculate on energy pro-duction mechanisms that are expected to operate in the immediate vicinity of the SBH.

This book provides a good summary of both the obser-vational and theoretical evidence for the existence of supermassive black holes, and is recommended to all who have an interest in extra-galactic astronomy, or high energy or gravitational physics. It should be noted that some attention is paid to observations with space-based telescopes that could help unequivo-cally establish their existence.

M. De Robertis Department of Physics York University

THE THEORY OF NUCLEAR MAGNETIC RELAXATION IN LIQUIDS, by James McConnell. Cambridge University Press, 1987, pp x+194. ISBN 0-521-321-12-3; QC145.4.M27M37. Price: $ 49.50.

In the preface the author, who has made significant contributions to the subject area of the book, states "...It is the purpose of the present book to provide, as far as space allows, a self-contained account of this theory." This scholarly and comprehensive mono-graph lives up to the promise. The reader is led with pithiness from the phenomenological treatment of spin relaxation to its microscopic theory. The necessary tools of Brownian motion, density matrix operator etc, are aptly developed and applied. The mathematical appendices are quite useful.

The book deals mainly with theory, although Chapter Eleven has some discussion of how theory compares with experiment. A highlight of this chapter is Sec-tion 11.2 which contains a summary of the main theo-retical results.

This book will be a valuable reference to those wish-ing to have an authoritative theoretical account of nuclear magnetic relaxation in liquids. Lastly, I must state that I find the price a bit high.

Amal K. Das Department of Physics Dalhousie University

WONDERING ABOUT PHYSICS USING SPREADSHEETS TO FIND OUT, by Dewey I. Dykstra, Jr., and Robert G. Fuller, John Wiley & Sons, 1988, pp x+122. ISBN 0-471 63174-4; QC52.D95. Price: $ 12.25 pbk.

Spreadsheets have been used by the business community to illustrate trends and ask the "what if" question. It should not come as surprise that spreadsheets can be used to investigate and document physics problems as well. What if a pendulum clock is on the moon? What if the mass of the car is doubled? What is the center of mass of a complex object? These are a few examples from Wondering about Physics...

This book is intended as a companion to a first year university, or advanced level high school text book. It contains about 50 problems which can be investi-gated using a spreadsheet. The problems are intended to be solved using numerical methods without recourse to calculus. The problems are taken from the standard textbook topics: F = MA, conservation of energy and momentum, simple harmonic motion, thermodynamics, op-tics, and electricity and magnetism. Each problem has

a theme, (for example how does the speed of a landing plane change during braking), suggestions on how to collect the data and set up the spreadsheet, some background information, a discussion of related sci-ence concepts and the relevant equations. Sometimes sample data is supplied. The reader is encouraged to make "what if" calculations using the spreadsheet, and make approximations or best guesses in the ab-sence of hard data. The authors do not spoon feed the solution to the students but provide enough instruc-tion that exploration of the problem is possible if the student is sufficiently motivated.

The book is humorously illustrated by one of the au-thors, Fuller. The Table of Contents gives the level of difficulty of each problem. No spreadsheet program mes are provided. An appendix with a few worked exam-ples would have been helpful.

Some background work would be required by the course instructor to prepare students to use this book. Pro-perly prepared students would find this book a good thought provoking guide to using spreadsheets as a tool to explore physics problems. It would serve as a useful supplement to their textbook. I would recom-mend Wondering about Physics... Using Spreadsheets to Find Out to anyone currently using spreadsheets to graph their data.

This text includes many examples of other uses for a spreadsheet.

James Freemantle C.R.E.S.S. York University

GRADUATE SCHOLARSHIPS MATERIALS RESEARCH

THE ONTARIO CENTRE FOR MATERIALS RESEARCH

ENTRY and CO-OPERATIVE RESEARCH SCHOLARSHIPS (15 Awards Annually)

Value $17,000 minimum

The applicants must be entering a program, or commenc-ing a thesis, leading to a PhD degree through research in materials at one of:

Queen's University McMaster University University of Toronto University of Waterloo University of Western Ontario

Competit ion closing date: January 5, 1990

For information, contact:

OCMR Administrative Office P.O. Box 1146, Kingston, ON K7L 4Y5 Phone: 613-545-6519 FAX: 613-545-6510


New Coatings for Excimer and YAG Lasers High damage threshold coatings allow the Ealing reflecting objectives to be used with YAG and Excimer Lasers in place of more conventional optical systems with all the inherent advan-tages of a reflecting system. • No chromatic and spheri-

cal aberration • Long working distances • Magnifications X15, X25,

X36, X52, X74

SEND FOR TECHNICAL LITERATURE

Ealing EALING SCIENTIFIC LIMITED

Call Toil-Free 1-800-361-1905 6010 Vanden Abeele, St. Laurent, Que. H4S 1FI9 Tel.: (514) 335-0792 Fax: (514) 335-3482

RESEARCH ASSOCIATE POSITION

SOLID STATE CHEMICAL PHYSICIST

Appl ica t ions are inv i ted for a permanent posi t ion of a Research Associate in a p rogram of exp lo r ing single-layer suspensions of t ransi t ion metal d ichalcogenides. M i n i m u m qual i f icat ions inc lude a Ph.D. in Physics w i th a s t rong background in t h in fi lms, powder suspensions and chemica l and electr ical measurements on such systems. The successful appl icant shou ld have at least t w o years' exper ience in f i lm depos i t ion techn iques f r om solut ions, character izat ion of th in f i lms w i t h X-ray d i f f rac t ion and e l l ipsometry and some exper ience in th in f i lm gas sensors. Salary $26,000 p.a.

Appl icants shou ld send thei r c.v., list of publ icat ions, and arrange for th ree letters of reference to be for-warded by September 30, 1989 to:

Dr. S.R. Morrison, Director Energy Research Institute Physics Department Simon Fraser University Burnaby, British Columbia Canada, V5A 1S6

In accordance w i t h Canadian Immigra t ion requi re-ments, p r io r i ty w i l l be g iven to Canadian ci t izens and permanent residents of Canada.

UNIVERSITY OF VICTORIA DEPARTMENT OF PHYSICS A N D A S T R O N O M Y

VICTORIA, BRITISH C O L U M B I A , C A N A D A .

FACULTY POSITION IN PHYSICS Applications are invited for a tenure-track posit ion at the rank of Assistant Professor to commence in 1990. The posit ion is in the area of Experimental Intermediate and High Energy Physics. The successful applicant wi l l have an established research record and have an interest in undergraduate and graduate teaching.

The current research interests of the Department in this area include rare decay experiments at TRIUMF and Brookhaven National Laboratory and the SLD experiment at the Stanford Linear Coll ider, as wel l as active part icipation in the proposal for a KAON facility based program at TRIUMF. In the future the group intends to maintain a balanced program of physics at High Energy Coll iders and Fixed Target Facilities. The close proximity of the TRIUMF Laboratory affords the oppor tun i ty for involvement in the TRIUMF program, and provides facilities for technological support and test beams for detector development, not normally present in a university department.

The University of Victoria offers equal employment opportuni t ies to qual i fed male and female applicants. W o m e n are particularly encouraged to apply. In accordance wi th Canadian Immigrat ion requirements, pr ior i ty wi l l be given to Canadian citizens and permanent residents.

Applications w i th curr icu lum vitae, publ icat ion list, and names and addresses of at least three referees should be sent to:

Professor L.P. Robertson, Chairman Department of Physics & Astronomy

University of Victoria VICTORIA, B.C.

V8W 2Y2

Applications wi l l be accepted unti l October 1, 1989.

TENURE TRACK FACULTY POSITION HIGH ENERGY AND NUCLEAR PHYSICS

Department of Physics University of Toronto

The Depa r tmen t of Physics plans to make one or possibly t w o tenure track appo in tmen ts w i t h star t ing date of lu ly 1,1990 at the rank of Assistant Professor. App l i ca t ions for these pos i t ions f r o m candidates in the areas of exper imen ta l or theore t i ca l h igh energy and nuc lear physics are inv i ted. Candidates w i t h demons t ra ted or po ten t ia l exce l lence in re-search and teach ing are sought . M e m b e r s of the h igh energy g r o u p are co l l abo ra t i ng in the study of charm, beauty and tau physics w i t h the ARGUS de tec to r , in the cons t ruc t i on of the ZEUS de tec to r for the study of h igh-energy e l e c t r o n - p r o t o n co l l is ions at HERA and in the ope ra t i on of the CDF de tec to r at the Fermi lab p r o t o n - a n t i p r o t o n co l l ider . Ma jo r areas of exper imenta l nuclear research inc lude: in te rmed ia te energy nuc l eon -nuc lea r react ions using accelerators at TRIUMF and IUCF, heavy- ion physics using TASCC and measurement of nuc lear cross sect ions of astrophysical interest using low-energy par t ic le accelerators. Theore t ica l act ivi t ies i nc lude an invest igat ion of quark physics p h e n o m e -no logy , the d e v e l o p m e n t of t e c h n i c o l o u r mode ls and gauge f ie ld theor ies of par t ic le physics and gravity, the d e v e l o p m e n t of so l i ton mode ls and mode ls of nuc lear co l lec t i ve mot ions , and the app l i ca t ion of g r o u p theo ry and symmet ry to p rob lems of subatomic physics. Theore t ica l appl icants in terested in w o r k at the in ter face be tween astrophysics and par t ic le physics w o u l d f i nd in teract ions w i t h CITA (Canadian Inst i tute of Theo-ret ical Astrophysics) at tract ive. App l i ca t ions consis t ing of a c u r r i c u l u m vitae; list of pub l ica t ions ; summary of research interests; a deta i led research proposal ; and the names, addresses and FAX numbers of th ree referees shou ld be sent as soon as possible, and no later than O c t o b e r 30, 1989 to: Professor M.B. Walker, Chair, Department of Physics, University of Toronto, Toronto, Ontar io, Canada M5S 1A7. In accordance w i t h Canadian Immig ra t i on requ i rements , this adver t isement is d i rec ted to bo th Canadian c i t izens and permanen t residents of Canada. The Un i -versity of T o r o n t o encourages b o t h w o m e n and m e n to apply for this pos i t ion .

Faculty Position in Experimental Condensed Matter Physics

Simon Fraser University Subject to final budget approval, the physics department at Simon Fraser University expects to have available a t e n u r e t rack facu l t y p o s i t i o n fo r an e x p e r i m e n t a l condensed matter physicist. The initial appointment wi l l be at the assistant professor level and wil l take effect in lanuary or September 1990. We are searching for an individual of outstanding background and exceptional promise who wi l l establish a vigorous independent re-search program and participate in the graduate and under-graduate teaching program of the department. Excellent candidates in any area of specialization wil l be given serious consideration. The present condensed matter research group consists of twenty full t ime faculty with broad research interests.

Simon Fraser University is an equal oppor tuni ty employer and encourages applications f rom women and minorit ies. In accordance wi th Canadian immigrat ion requirements, this advertisement is directed to Canadian citizens and permanent residents. Applicants should send vitae, pub-lication list and the names of at least three references to: Professor M. Plischke, Chairman, Department of Physics, Simon Fraser University, Burnaby, B.C. Canada V5A 1S6 by October 15, 1989.

TENURE TRACK FACULTY POSITION

GEOPHYSICS


The Depar tment of Physics plans to make one or possibly t w o tenure track appo in tments , w i t h start ing date of July 1, 1990, at the rank of Assistant Professor. Candidates w i t h demonst ra ted or potent ia l excel lence in research and teach ing are sought. The geophysics g roup cur rent ly has faculty members w o r k i n g in argon and lead geochrono logy , rock and paleomagnet ism, theoret ica l and exper imenta l seismology, e lect romag-netic methods and appl ied geophysics, and crustal and mant le dynamics. Candidates in these or c o m p l e m e n -tary f ields are inv i ted to apply. Appl ica t ions consist ing of a cu r r i cu l um vitae; list of publ icat ions; summary of research interests; a detai led research proposal; and the names, addresses and FAX numbers of three referees shou ld be sent as soon as possible and no later than Oc tobe r 30, 1989 to: Professor M.B. Walker, Chair, De-partment of Physics, University of Toronto, Toronto, On-tario, Canada M5S 1A7. In accordance w i t h Canadian Immigra t ion requi rements, this advert isement is di-rected to bo th Canadian cit izens and permanent res-idents of Canada. The Universi ty of To ron to encourages bo th w o m e n and men to apply for this posi t ion.

MEDICAL PHYSICIST

Saskatoon Cancer Centre

An immediate opening exists for a Medical Physicist in the Saskatoon Cancer Centre. The successful applicant wi l l jo in a group of professional physicists providing a ful l range of services in the Radiotherapy Department of the Cancer Centre and in the Nuclear Medic ine Department of the University Hospital.

The ideal candidate wi l l broaden the range of expertise w i th in the group. The responsibil it ies of the group cover a broad range including radiation physics, comput ing and advanced instrumen-tation engineering.

The Saskatoon Cancer Centre is located in a new custom-bui t bui ld ing on the University of Saskatchewan campus. The Radi-otherapy Department is equipped wi th 3 accelerators, Cobalt unit, simulator, VAX-based treatment planning system. We have a well-equ ipped dosimetry laboratory, workshop and mould room. Approximately 1200 patients are treated wi th radiation each year.

This posit ion provides an attractive salary and fr inge benefits. There are opportuni t ies for research, and it is expected that the successful applicant wi l l receive an academic appointment at the University of Saskatchewan.

Candidates must have a graduate degree in Physics or a related subject. Please submit a cur r icu lum vitae and the names of three references.

Send applications to: Dr. Alistair Baillie Chief Medical Physicist Saskatoon Cancer Centre 20 Campus Drive University of Saskatchewan Campus Saskatoon, Saskatchewan S7N 4H4

POST DOCTORAL POSITIONS

University of British Columbia O u t s t a n d i n g cand ida tes are b e i n g sough t t o f i l l t w o Post D o c t o r a l pos i t i ons in e x p e r i m e n t a l physics. O n e research area is c e n t e r e d o n h i gh t e m p e r a t u r e su-p e r c o n d u c t o r s , w h i c h i n c l u d e mater ia l synthesis, m e a s u r e m e n t of f u n d a m e n t a l p rope r t i es by DC e lec-t r ica l , magne t i c , and m i c r o w a v e t e c h n i q u e s , in te rna l magne t i c s t r u c t u r e and o t h e r p rope r t i es via m u o n sp in resonance (at T r i um f , t h e m e s o n fac to ry l oca ted o n t h e U B C campus) , spec i f i c heat, and nuc lear magne t i c resonance . T h e s e c o n d research area is c o n c e r n e d w i t h l o w t e m p e r a t u r e a t o m i c h y d r o g e n and d e u t e r i u m , spec i f i ca l l y sp in -a l i gned H and D, c r y o g e n i c h y d r o g e n masers and re la ted areas of l o w t e m p e r a t u r e physics. T h e l o w t e m p e r a t u r e g r o u p possesses t h r e e 3 H e / 4 H e d i l u t i o n re f r igera to rs and has t r ad i t i ona l l y c o n c e n t r a t e d o n r.f., m i c r o w a v e and m i l l i m e t e r w a v e t echn iques .

Prospec t i ve cand ida tes s h o u l d send resume a l o n g w i t h names of 3 re fe rences to: W .N . Hardy, Depart-ment of Physics, University of British Columbia, 6224 Agriculture Road, Vancouver, B.C. CANADA V6T 2A6, before October 31, 1989.

McMASTER UNIVERSITY MEDICAL PHYSICIST

The Department of Physics at McMaster University invites applications for an Assistant Professorship in Medical Physics. The successful candidate will be expected to establish a research programme centred in the Physics Department and contribute to the teaching of both the existing M.Sc. pro-gramme in health and radiation physics as well as a developing medical physics doctoral programme. These programmes are currently run by a group of seven professional medical physicists who are associate members of the Department and whose primary appointments are in Hamilton hospitals or the Regional Cancer Centre. Favourable research areas for the successful applicant might be lasers, magnetic resonance, ultrasound, instrumentation, biomedical computing or pros-thetics and biomaterials. Expected start date is July, 1990 subject to University budget approval.

In accordance with Canadian Immigration requirements, this advertisement is directed to Canadian citizens and permanent residents. However, applications from all outstanding candi-dates will be considered. This position is open to both men and women. Closing date for receipt of applications for this competition will be November 30, 1989.

Applicants should send a curriculum vitae, an outline of proposed research and the names of three referees to:

Dr. P.G. Sutherland, Chairman Department of Physics McMaster University Hamilton, Ontario, Canada L8S 4M1

MEDICAL PHYSICIST Applications are being accepted for the position of medical physicist at the Kingston Regional Cancer Centre of the Ontario Cancer Treatment and Research Foundation. The Centre is closely associated wi th the Kingston General Hospital and Queen's University. We treat approximately 1100 new patients per year, teach students at both the graduate and undergraduate level, and have a research program in medical physics.

The candidate wil l preferably have a PhD, although ex-ceptional candidates with an MSc wil l be considered. Several years' experience in the field of medical physics are required. The successful candidate wil l be expected to participate in the clinical, educational arid research activities of the Medical Physics Department: this includes applying for research funds and the supervision of graduate students.

The successful candidate can expect to receive an aca-demic appointment in the Department of Oncology and a cross-appointment in the Physics Department at Queen's University.

This position is available immediately.

The Foundation offers a competi t ive salary and benefit package.

Please mail a curr iculum vitae and the names of three referees to: Dr. Peter Shragge, Head of Physics, Kingston Regional Cancer Centre, King Street West, Kingston, Ontario K7L 2V7.

TENURE TRACK FACULTY POSITION

CONDENSED MATTER AND QUANTUM OPTICS


The Department of Physics plans to make one or possibly two tenure track appointments, wi th starting date of July 1, 1990 at the rank of Assistant Professor. Applications for these positions from candidates in the areas of experi-mental or theoretical condensed matter and quantum optics are invited. Candidates wi th demonstrated or po-tential excellence in research and teaching are sought. The recent establishment of the Ontar io Laser and Light-wave Research Centre and a strong group in high temper-ature superconductivity emphasize the commitment of the Department to the broad area of condensed matter and quantum optics. Applications consisting of a curr iculum vitae; list of publications; summary of research interests; a detailed research proposal; and the names, addresses and FAX numbers of three referees should be sent as soon as possible, and no later than October 30,1989 to: Professor M.B. Walker, Chair, Department of Physics, University of Toronto, Toronto, Ontario, Canada M5S 1A7. In accordance with Canadian Immigration requirements, this advertise-ment is directed to both Canadian citizens and permanent residents of Canada. The University of Toronto encourages both women and men to apply for this position.

i M

McGill University FACULTY P O S I T I O N I N PHYSICS

The Department of Physics invites applications for a tenure-track posit ion in experimental sub-atomic physics at the rank of Assistant Professor commencing as early as January 1, 1990. Preference wil l be given to candidates wi th an established research record and a creative potential for generating excit ing research in experimental relativistic heavy ion coll ision physics. Strong interest in undergrad-uate and graduate teaching is also a prerequisite.

Applications, together wi th curr icu lum vitae and letters of recommendat ion f rom three referees, should be sent to:

Professor S. K. Mark, Chairman Department of Physics Ernest Rutherford Physics Building McGill University 3600 University Street Montreal, Quebec, Canada H3A 2T8

In accordance wi th the Canadian immigrat ion regulations, prior i ty wi l l be given to Canadian citizens and permanent residents of Canada.

U N I V E R S I T Y O F T O R O N T O DEPARTMENT OF CHEMISTRY

TENURE-STREAM APPOINTMENT

Applications for a tenure-stream appointment at the Assistant Professor Level in Experimental Polymer Chemistry are solicited. Applicants should possess a strong academic background and an excellent research record. The successful candidate wil l be expected to conduct an active and highly innovative research program and to teach at both undergrad-uate and graduate levels.

This position is open to men and women candidates of any nationality. Applicants should provide a cur-r iculum vitae and an outl ine of their proposed research for the first three years, and should arrange to have four letters of recommendation sent on their behalf, as soon as possible and not later than De-cember 15th, 1989.

Attention: The Chair, Polymer Search Committee Department of Chemistry

University of Toronto 80 St. George Street

Toronto, Ont. Canada M5S 1A1

CANADIAN INSTITUTE FOR THEORETICAL ASTROPHYSICS / INSTITUT CANADIEN

D'ASTROPHYSIQUE THEORIQUE

RESEARCH FELLOWSHIPS

CITA is a national centre for theoretical astrophysics located at the University of Toronto. The Institute expects to offer five to ten research fellowships with a starting date of September 1, 1990. The appoint-ments wil l be of two kinds: postdoctoral fellows (two years duration) and research associates (three years renewable to five). Funds wil l be available to each fellow for travel and other research expenses. Fellows are expected to carry out original research in theo-retical astrophysics under the general supervision of the permanent faculty or visitors to CITA, whose interests include: cosmology, interstellar matter, nu-clear and relativistic astrophysics, star formation, stellar structure, active galactic nuclei and galactic and solar system dynamics.

Applicants should send a curr iculum vitae and state-ment of research interests and must arrange them-selves for three letters of recommendation to be sent to: Prof. S. Tremaine, Director, Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario CANADA M5S 1A1.

APPLICATION DEADLINE IS DECEMBER 31, 1989.

U N I V E R S I T Y O F T O R O N T O DEPARTMENT OF CHEMISTRY

TENURE-STREAM APPOINTMENT

The depar tment of Chemistry, Universi ty of To ron to w i l l make a tenure-st ream appo in tmen t at the Assistant Professor level in Experimental Physical Chemist ry on or after January 1, 1990. Appl icants shou ld possess a strong academic background and an excel lent research record in any area of m o d e r n exper imenta l physical chemistry. The successful candidate wi l l be expected to conduc t an active and h ighly innovat ive research program and to teach at bo th the undergraduate and graduate level.

Appl icat ions shou ld be submi t ted by December 15, 1989. M e n and w o m e n appl icants, w h o may be of any nat ional i ty, shou ld prov ide a cu r r i cu lum vitae and an ou t l i ne of their p roposed research, and shou ld arrange to have three letters of r ecommenda t i on sent on the i r behalf to:

The Chair Attention: Experimental Physical Chemistry

Department of Chemistry University of Toronto

Toronto, Ont. Canada M5S 1A1

Assistant Professors Department of Physics T h e D e p a r t m e n t o f Phys ics an t i c ipa tes a n u m b e r o f t e n u r e - t r a c k a p p o i n t m e n t s i n severa l f i e lds o f phys ics o v e r the n e x t f e w years . C u r r e n t f ie lds o f emphas i s i n t h e D e p a r t m e n t are C o n d e n s e d M a t t e r Physics, Geophys i cs , G r a v i t a t i o n a n d A s t r o p h y s i c s , and S u b a t o m i c Physics. A p p l i c a t i o n s f r o m o u t s t a n d i n g i nd i v i dua l s h a v i n g a p r o v e n ab i l i t y o r a d e m o n s t r a t e d p o t e n t i a l f o r exce l lence i n t each ing a n d research a re i n v i t e d .

W e speci f ica l ly seek cand ida tes f o r t w o t e n u r e - t r a c k pos i t i ons a t t h e Ass i s tan t P ro fesso r level b e g i n n i n g July 1, 1990 in the f ie lds o f e x p e r i m e n t a l C o n d e n s e d M a t t e r Physics a n d in e x p e r i m e n t a l S u b a t o m i c Physics. I n C o n d e n s e d M a t t e r Phys ics w e have a specif ic i n te res t i n e l e c t r o n m i c r o s c o p y A p p o i n t m e n t o f an excep t i ona l cand ida te a t a m o r e sen io r level m a y be cons ide red . In accordance w i t h C a n a d i a n I m m i g r a t i o n r egu la t i ons , th i s a d v e r t i s e m e n t is d i r ec ted t o C a n a d i a n c i t i zens a n d p e r m a n e n t res iden ts .

T h e A s s i s t a n t P ro fesso r sa lary r ange is f r o m $ 3 4 , 9 7 0 t o $ 5 1 , 4 3 4 per a n n u m , d e p e n d i n g u p o n exper ience .

Send c u r r i c u l u m v i tae and t h e n a m e s o f t h ree (3) re ferees, by D e c e m b e r 15, 1 9 8 " to :

C h a i r m a n , S e a r c h C o m m i t t e e D e p a r t m e n t o f P h y s i c s U n i v e r s i t y of A l b e r t a E d m o n t o n , A l b e r t a T 6 G 2J1

The University of Alberta is committed to the principle of equity in employment.

INDUSTRIAL RESEARCH FELLOWSHIPS

M P B T e c h n o l o g i e s I n c . is s e e k i n g c a n d i d a t e s t o n o m i n a t e f o r N a t u r a l S c i e n c e a n d E g n i n e e r i n g C o u n c i l o f C a n a d a I n d u s t r i a l R e s e a r c h F e l l o w s h i p s .

T h e F e l l o w s h i p s w i l l n o r m a l l y b e t e n a b l e i n t h e L a b o r a t o r i e s o f M P B T e c h n o l o g i e s I n c . l o c a t e d a t D o r v a l , Q u e b e c o r O t t a w a , O n t a r i o .

P r o j e c t s i n w h i c h s u c c e s s f u l c a n d i d a t e s m a y b e i n v o l v e d i n c l u d e :

• E l e c t r o m a g n e t i c s a n d M i l l i m e t e r W a v e s • Lasers a n d Laser A p p l i c a t i o n s • E l e c t r o - o p t i c s a n d A c o u s t o - o p t i c s • P l a s m a , F u s i o n a n d S p a c e T e c h n o l o g y • E x p e r t S y s t e m s a n d A r t i f i c i a l I n t e l l i g e n c e • R o b o t o t i c s

Sa la r i es a n d o t h e r b e n e f i t s a r e t h e s a m e as f o r p e r m a n e n t s ta f f o f e q u i v a l e n t e x p e r i e n c e .

I n t e r e s t e d r e c e n t g r a d u a t e s , i n d i v i d u a l s c u r r e n t l y c o m p l e t i n g p o s t d o c t o r a t e f e l l o w s h i p s , o r c a n d i d a t e s w h o w i l l g r a d u a t e i n t h e n e a r f u t u r e w i t h a b a c k g r o u n d i n p h y s i c s , e l e c t r i c a l e n g i n e e r i n g o r c o m p u t e r s c i e n c e a n d w h o a r e C a n a d i a n c i t i z e n s o r l a n d e d i m m i g r a n t s a r e i n v i t e d t o w r i t e o r c a l l :

D r . M . P . Bachynski M P B Technologies Inc. 1 7 2 5 N o r t h Service Road T rans -Canada H i g h w a y D o r v a l , Q u e b e c C A N A D A , H 9 P 1J1

Te lephone: (514) 6 8 3 - 1 4 9 0 Fax: ( 5 1 4 ) 6 8 3 - 1 7 2 7

Meeting All Your CAMAC/FASTBUS Needs For Laboratory

Automation

...FOR YOUR TIME-CRITICAL DATA ACQUISITION and CONTROL NEEDS

Whether you want a complete data acquisition and control system with application software or just modules and crates, see how fully KSC serves your needs.

ALSO AVAILABLE: C H A R T R E C O R D E R S

P R E S S U R E T R A N S D U C E R S

P R E S S U R E S T D S

TECHNEL

TECHNEL E N G I N E E R I N G I N C . 120 Whltmore Rood. N° B P O BOX 15, Woodbrldge Ontario Canada. L4L 1A9 Tel. (416) 851-4244 Fax: 1416) 851-5743

For a more deta i led exp lanat ion of ou r p roduc ts and services,

call COLLECT 416-851-4244

Canadian Association of Physicists Association canadienne des physiciens

This certifies that Ceci atteste que

is a member in good standing of the Association est membre en règle de l'Association

President

Président

Date of issue

Date d'émission

• • • • • Build Your • • • • •

Future • » > • • with •

* Newport *

Because you need a lot more than specifications, it's a lot more than a catalog

All new for 1989 The Newport Catalog has

always been the most convenient place to find research-quality laser and optics products. Now, with the addition of over 100 new products and an easy-to-use format, it's even better.

Reserve your copy Order your copy of the new

Newport Catalog by calling us at (416) 826-7752

CV> N e w p o r t Unshakeable Quality

t ® Technical Marketing Associates Limited

6695 Millcreek Rd„ Unit 1. Mississauga, Ont L5N 5R8 Telephone: (416) 826-7752 • Fa*: (416) 826-8225

At 500pages, it's by far the most comprehensive guide 3 precision laser and optics components.

©1988 08891 -A Newport Corporation

vol. 45,no.5 la physique au canada septembre 1989 … · symmetries in physic — ths e unitar...

Documents