d.l. balabanskiphysics of nuclei at extremes, t.i.tech, 26.01.2010 1 nuclear moments and structure...

D.L. Balabanski Physics of Nuclei at Extremes, T.I.Tech, 26.01.2010

1

Nuclear moments and structure of isomers in regions far from stability

Dimiter L. BalabanskiInstitute for Nuclear Research and Nuclear Energy

Bulgarian Academy of Sciences


2

781 A.D.


3


4

basic definitions

experiments with fast beams• orientation in fragmentation reactions• how to approach ground state moments of exotic nuclei• how to approach isomeric states • how to approach short-lived states• what can we learn from such measurements

outlook• experiments with post-accelerated ISOL beams

Nuclear moments and structure of isomers in regions far from stability

Dimiter L. BalabanskiInstitute for Nuclear Research and Nuclear Energy

Bulgarian Academy of Sciences


5

+ 6 more pages

193Pb

key issue: week exotic excitations

e.g. magnetic rotation


6

key issue: week exotic excitations

e.g. chiral rotation

128Cs


7

Q,

Q,

Z = 28

N =

40

key issue: shell structure away from stability


8

A schematic view of the basic methods of producing

radioactive nuclear beams. At the top we see the ISOL

method with and without a post-accelerator. Below we see

the In-flight method and the proposed hybrid in which

fragments are caught in a gas cell and then re-accelerated.

In-flight

Accelerator

Thin productiontarget

Fragmentseparator

In-flight post-accelerator

Gas stopper

Separator

Accelerator

Experiments

ISOL

Accelerator

Thick productiontarget

ISOL

ISOL trap

Beam manipulation

Post-accelerator

Beam manipulation

Separator

Experiments

ISOL post-accelerator

The European perspective:present day • ISOL: ISOLDE• in-flight: GSI, GANIL post-accelerated ISOL:

REX-ISOLDEnear future•in-flight: FAIR• post-accelerated ISOL: Spiral2, HIE-ISOLDEfar future: EURISOL

In-Flight


9

Nuclear moment measurements

magnetic moment () quadrupole moment (Q)

single-particle configuration (configuration mixing)

collective properties(deformation, effective charges)

Spin-orientedbeams


10

Spin-aligned and spin-polarized beams some definitions

m-2 –1 0 +1 +2

m-2 –1 0 +1 +2

spin-alignment

spin-polarization


11

= gl.l + gs.s

= <j, m=j | z | j,m=j>

(j=l + 1/2) = 1 1

2 2l s Nj g g

(j=l -1/2) =

3 1

1 2 2l s N

jj g g

j

some more definitions

Magnetic dipole moment in atomic nuclei

(I) = <I, m=I | ( . . )i i i il z s z

i

g l g s | I,m=I>

• orbital momentum of the protons• intrinsic spin of the nucleons

Schmidt lines


12

odd protonodd neutron

j = l + 1/2

j = l – 1/2

j

j = l – 1/2

j = l + 1/2

j

Schmidt lines


13

yet more definitions

Electric quadrupole moment in atomic nuclei

Q =

2 2(3. )i i ii

e z r = 2

2 ( , )i i i ii

e r Y .

Q = 02, ,I m I I m I Q

Q(j) =

22 1

2( 1)j j

je r

j


14


15

experimental approach

Basic principles for moment measurements (ground states)

magnetic dipole moments: experiments in external magnetic fields

electric quadrupole moments: interaction with external electric fields, e.g. with a lattice field after implantation

signal for -decaying ground states: GT -decay asymmetry (-NMR, -NQR)see talk of A.Yoshimi

requirement: polarization of the spin ensemble


16

B

JFragment beam

L = -gNB/h

Measure Larmor precesionand decay I(t)

Time Differential Perturbed Angular Distribution

t=0 time

Field UPField DOWN

2L

2A2B2

the relative phases depend on the g-factor

time

1 2

1 2

( )I I

R tI I

detectors at ±45° and ±135°detectors at ±45° and ±135°

isomeric sates (ns − s) requirement: alignment of of the spin ensemble

signal : time dependence of the intensity of the decay rays TDPAD


17

ALIG

NM

EN

T(%

)

+6.2(7)%

GENERAL ASPECTS of g-factor measurements with fast beams

4. FEASIBILITY: SPIN-ALIGNMENT !

PROJECTILE FRAGMENTATION +

selection in longitudinal momentum(slits in FRS or via ion-correlation)

CONDITION:STRIPPED FRAGMENTS !

61FeYIELD

61Fe

-15.9(8)%

61Fe

61Fe


18


19


20


21

1/2-

5/2+

9/2+

694

313T1/2 = 13.3 s

67Ni

1 2 3 4 5 s

auto

corre

latio

nR(

t)

0 5 10 15 20 25L (Mrad/s)

Ampl

itude

Fourrier spectrum

G. Georgiev et al. J.Phys. G 28, 2993 (2002)


22

76Ge @ 130 MeV/u; 9Be targetA1900 – 90% beam purity


23

I. Matea et al. PRL 93 (2004) 142503


24

207 keV M1 transition 654 keV M2 transition

Q(61mFe; g9/2) = 41(6) mb

GANIL did a press release on this result !Time-differential perturbed angular distributions

test case 61Feexp. July 2005

principle investigators: Micha Hass (Rehovot) and Jean-Michel Daugas (Bruyeres-la-Chatel)

Analysis: Nele Vermuelen, Leuven and Chamoli, Rehovot (PR C 75, 051302)

2 = - 0.21 or +0.24


25

(d,p) reaction, Tandem-ALTO, Orsay

Qs(61Fe; 9/2+)= 41(6); 2 > 0 Qs(65Cu; 3/2−) = −19.5(4); 2 < 0

Qadd = QQ = 21.5(60) efm2


26

classical view quantum-mechanical view

Pop

ula

tion

I = 2

E

m =2m =1

m =0m =-1

m =-2

I=2 ensemble

Necessary to induce polarization of the beam prior the measurement

ISOL beams


27

Electromagnetic moments in transfer reactions

98Mo 99Mo

100Tc

100Mo 101Mo

102Tc

63Cu 64Cu

65Zn

65Cu 66Cu

67ZnP P

• populate low-spin (single-particle) states• go a step further in the Nuclear Terra Exotica

G. Georgiev (Orsay, France) and D.L. Balabanski (INRNE – BAS, Sofia)

http://www.zoomwhales.com/language/english/label/tools/answers.shtml


28

What do we want to do next ?targets: 62,64Ni beams: 63,65Cu

test case: g = +0.177(5)

Cu-beam

D2 target

electromagnet

3.5 MeV/uS2 detector of TIARA

T1/2 = 20ns

use particle – coincidences instead of beam pulsing

http://www.zoomwhales.com/language/english/label/tools/answers.shtml


29

inverse kinematics63Cu beam @ 220 MeV (3.5 MeV/u)

CD2 target (2 mg/cm2)

Ni ferromagnetic backing (15 µm)

permanent magnet for holding fieldParticle identification: Si strip detector (8 annular strips) as ECsI 16 sectors – as E detector angular coverage 25° - 60°

ADWA (d,p) calculations for 3.5 MeV/u 63Cu beams

0.00

0.10

0.20

0.30

0.40

0.50

0.60

10 40 70 100 130laboratory angle (degrees)

mb/sr

cu64 6- isomer 3.76 mb


30


31

The CD detector of TIARA

The CsI detector

Particle detection with TIARA(in collaboration with Surrey, Birmingham)


32


33


34

Particle- vs. beam pulsing

Try to avoid the particle- correlations if not absolutely necessary


35

short-lived (ps) states

Transient field technique

requirement: alignment of of the spin ensemble

signal: rotation of the angular distribution of the rays

interaction: very high transient magnetic field (tens of Tesla)


36


37

Honma et al., PR C 80, 064323 (2009) in the calculation f7/2 is frozen!

Question: Is there deviation from the hydrodynamic limit?


38

1. Spin-alignment in projectile fission and g-factors around 132Sn (Gerda Neyens and Gary

Simpson)

g-RISING EXPERIMENTS performed Oct – Dec. 2005

2. Spin-alignment and g-factors of isomers in 127,128Sn from fragmentation of a 136Xe beam. (Dimiter Balabanski and Michael Hass)

Sn

238U-fission at 750 MeV/u 136Xe-fagmentation at 700 MeV/u


39

THE EXPERIMENTAL SET-UP AT GSI: g-RISING

Spin-aligned secondary beam selected(S2 slits + position selection in SC21)

SC41 gives t=0 signal for -decay time measurement

Implantation: plexiglass degrader + 2 mm Cu (annealed)

SC42 and SC43 validates the event


40


41

The 136Xe fragmentation experiment

Z

A/q

127Sn

analysis:L.Atanasova, Sofia


42

Momentum selection

Position at Sc21

Isom

eric

rat

io (

arbi

trar

y un

its)

25%


43

128Sn

127Sn

J. Pinston et al., PRC 61, 024312 (2000)

4.5(3) s -ray spectra gated on 127Sn


44

s isomers in the Sn region NN=82=82

1g7/2

1h11/2

3s1/2

2d3/2

2d5/2

NN=50=50

J. Pinston et al, PRC61 024312 (2000) , J. Pinston et al, JPG30 (2004) R57,NNDC data base and this work

d3/2-1h11/2

-1

Odd Sn

Even Sn

d3/2-1h11/2

-2

h11/2 -d3/2

-1h11/2 -1

d3/2-1h11/2

-2

h11/2 x 5- core h11/2 x 7- core

h11/2 -

h11/2

s1/2-1

d3/2-2

Brown et al, PRC71 (2005) 044317

Newly identifiedisomers

R. Lozeva, PR C 77, 064313 (2008)


45

B = 0.12 T g = - 0.15

Choice of the magnetic field

g = 0.16

R(t, R(t, ±B) = ±B) = 3A3A

4+A4+A sin(2sin(2LLt)t)

1 2

1 2

( )I I

R tI I

I1 = (A+L) + (D+G) I2 = (A+L) + (D+G)


46

1095 keV

715 keV

FFT

TDPAD

715 keV L. Atanasova, Europhys. Letters in preparation

g = 0.17(2)


47

G.Ilie et al, Phys. Lett. (submitted)

Analysis S.K. Chamoli; L. Atanasova et al, Europhys. Lett. (in preparation)

g(7; 126Sn) = 0.097(3)

g(10+; 128Sn) = 0.20(4)


48

7

10+

19/2+

7 : 114,116Sn and 130Sn10+ : 116,118Sn19/2+ : none

Sn neutron-rich isomers

11/2


49

Structure of the 19/2+ isomer in 127Sn

• the spin-parity assignment of the 19/2+ isomer is based on energy systematics J. Pinston et al., PRC 61, 024312 (2000)

• suggested configuration: (ννh11/2 1 5)19/2+; gexp(h11/2) = 0.24

• the 5 isomers in even-even Sn isotopes take experimental values: gexp(5) 0.06 and are understood as an admixture of (ννh11/2

1d3/2 1)5- with gemp = 0.26

(ννh11/2 1s1/2

1)5- with gemp = 0.09

• for the structure of the 19/2+ isomer an admixture with the νg7/2 1h11/2

2 configuration is

suggested in order to explain the l -forbidden M2 isomer-decay transition.

gemp(νs1/2 1 h11/2

2) = 0.15 gemp(νg7/2

1 h11/2 2) = 0.23

• the fragmentation g-RISING experiment yields gexp = 0.17(2)

• LSSM calculations yield gSM = 0.11 (calculation M.Hjorth-Jensen)


50

1. K.U. Leuven, Belgium: M. De Rydt, R. Lozeva, S. Mallion, G. Neyens, K. Turzó, N. Vermeulen2. INRNE, Sofia, Bulgaria: D.L. Balabanski3. University of Sofia, Bulgaria: L. Atanasova, P. Detistov 4. ILL Grenoble, France: G. Simpson5. CEA, Bruyères le Chatel, France: J.M. Daugas, O. Perru6. CSNSM – Orsay, France: G. Georgiev7. ISKP Bonn, Germany: H. Hübel, S Chmel8. GSI-Darmstadt, Germany: F. Becker, P. Bednarczyk, L. Caceres, P. Doornenbal, J. Gerl, H. Grawe, M. Górska, I. Kojuharov, N. Kurz, W. Prokopowicz, T. Saito, H. Schaffner,

E. Werner-Malento, H.J. Wollersheim

9. IKP Koeln, Germany: J. Jolie, G. Illie, A. Blazhev10. IKHP Rossendorf, Germany: R. Schwengner, G. Russev11. ATOMKI, Debrecen, Hungary: A. Krasznahorkay12. The Weizmann Institute, Israel: S. Chamoli, M. Hass, S. Lakshmi13. University of Camerino, Italy: G. Lo Bianco, A. Saltarelli14. LNL Legnaro, Italy: J.J. Valente-Dubon15. University of Milano, Italy: G. Benzoni, N. Blasi, A. Bracco, F. Camera, F. Crespi, D. Montanari, O. Wieland 16. U. Padova and INFN Padova, Italy: D. Bazzacco, E. Farnea17. INFN-Perugia, Italy: K. Gladnishki18. IFJ-PAN Krakow, Poland: J. Grębosz, M. Kmiecik, A. Maj, K. Mazurek, W. Męczyński, S. Myalsky, J. Styczeń, M. Ziębliński 19. Jaggielonian University, Krakow, Poland: R. Kulessa 20. Warsaw University, Poland: M. Pfűtzner21. NIPNE, Bucharest, Romania: M. Ionescu-Bujor, A. Iordachescu 22. Universidad Autonoma de Madrid, Spain: A. Jungclaus 23. Univerity of Lund, Sweden: C. Fahlander, R. Hoishen, D. Rudolf24. University of Surrey, UK: Zs. Podolyàk, P. Regan, J. Walker, S. Pietri, C. Brandau.

The g-RISING collaboration: 71 researchers from 24 institutions


51

Quadrupole moment measurement of the 8+ isomer in 96Pdusing the RISING stopped-beam set up

Spokespersons : Michael Hass (WI) and Dimiter Balabanski (Sofia/Camerino)

GSI contact: Juergen GerlINRNE, Bulgarian Academy of Sciences, Bulgaria: D.L. BalabanskiWeizmann Institute, Israel: G. Goldring, M. Hass, V. KumarUniversity of Sofia, Bulgaria: L. Atanasova, P. Detistov, K. Gladnishki, S. Lalkovski, G.I. RainovskiCSNSM, Orsay, France: G. GeorgievK.U. Leuven, Belgium: M. De Rydt, R. Lozeva, G. Neyens, N. VermeulenUniversity of Camerino, Italy: G. Lo Bianco, A. Saltarelli, S. NardelliUniversity of Milano, Italy: G. Benzoni, N. Blasi, A. Bracco, F. Camera, F. Crespi, S. Leoni, B. Million, O. WielandLNL, Padova, Italy: G. De Angelis, A. Gadea, R. Orlandi, E. SahinUniversity of Surrey, UK: A. Garnsworthy, S. Pietri, Zs. Podolyàk, P. Regan, S. SteerUniversity of Brighton, UK: A. M. BruceUniversity of York, UK: B.S. Nara SinghUniversidad Autonoma de Madrid, Spain: L. Caceres, A. Jungclaus, V. Modamio, J. WalkerUniversity of Istanbul, Turkey: M.N. ErduranIKP Koeln, Germany: A. Blazhev, G. Ilie, J. JolieUniversity of Lund, Sweden: D. Rudolph, C. Fahlander, R. HoisenIFJ PAN Krakow, Poland: A. Maj, M. Kmiecik, J. Grebosz, P. Bednarczyk, K. Mazurek, S. MyalskiGSI-Darmstadt, Germany: F. Becker, C. Brandau, P. Doornenbal, J. Gerl, M. Gorska, H. Grawe, I. Kojuharov, N. Kurz, W. Prokopowicz, H. Schaffner, S. Tachenov, H.J. Wollersheim

An experiment that we could not make!


52

in this experiment we aim to measure the quadrupole moment of the 8+ isomer in 96Pd which has four holes in the Z = 50 shell

Sn

MOTIVATION: Q(8+) is a probe for the break down of the g9/2

n seniority scheme


53

Seniority mixing has been experimentally established from a measurement ofB(E2) transition strengths from the 4+ states in 96Pd and 94Ru. Large scale shellmodel calculations fully account for the experimental data in 96Pd and 94Ru and

prove that the mixing is due to ph excitations across the N=50 closed shell. H. Grawe et al, EPJ A (2006)

20% spread of predictions


54

The 8+ isomer in 96Pd was produced in the fragmentation of the 107Ag beam at 750 MeV/u during S244 RISING experiment; we suggest to perform the moment

measurement under the same conditions

PRODUCTION OF THE 96Pd ISOMER


55

Polarized beams at HIE-ISOLDE – from dreams to reality.

G. Georgiev1, M. Hass2, A. Herlert3, D.L. Balabanski4, L. Hemmingsen5, K. Johnston3, M. Lindroos3, K. Riisager6, J. Van de Walle3, D. Voulot3, F. Wenander3, W.-D. Zeitz7

1. CSNSM, Orsay, France; 2. The Weizmann Institute, Rehovot, Israel; 3. ISOLDE, CERN, Geneva, Switzerland; 4. INRNE, BAS, Sofia, Bulgaria; 5. IGM, LIFE, University of Copenhagen, Denmark; 6. Department of Physics and

Astronomy, University of Aarhus, Denmark; 7. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany

Polarized beams – WHY?

p

dd

pdd

dd

dd

Ay

Precise test of the nuclear models for exotic nuclei: • transfer reactions(analyzing power)• Coulomb excitation – spin/parity;multiplicity assignments etc.• nuclear moments – proton/neutron character, angular momentum j

21 j


56

Can one do it and how?

M. Hass et al., NPA 414, 316 (84)

Tilted Foils - the principles: • atomic polarization nuclear polarization• higher nuclear spins higher polarization (>10% achieved so far)• strong velocity dependence (poorly studied up to now)

•Can one post-accelerate the ions after polarizing them?done for stable beams - noble-gas like charge states + LINAC J. Bendahan et al., ZPA 331, 343 (88)


57

- unique opportunity

What do we need to achieve it?

3 MeV/u and 0.3 MeV/u

-NMR setup from HMI Berlin transferred to ISOLDE

• gain of complete control on the TF polarization

• nuclear structure (moments, reactions …),

nuclear methods in the solid-state physics,

biophysics etc. …


58

Conclusions• fragmentation reaction at intermediate energies are proved to be a reliable tool for nuclear moment measurements; • fragmentation reactions at relativistic energies are rather difficult to handle, BUT need to be used for medium and heavy nuclei; • transfer reactions (and incomplete fusion) are an option to approach neutron-rich nuclei; • polarization of post-accelerated beams is the next c hallenge to address


59

This work wouldn’t have been possible without the fruitful collaborations with my friends

Georgi Georgiev,Gerda Neyens,Micha Hass, andJean-Michel

Daugas

d.l. balabanskiphysics of nuclei at extremes, t.i.tech, 26.01.2010 1 nuclear moments and structure...

Documents