Organizer: T. Ferbel Scientific Secretaries: R. J. Abrams

K. P. Pretzl J. J. Whitmore

High Energy Collisions III: • Production Processes at High Energies, Experimental

HIGH-ENERGY COLLISIONS III - PRODUCTION PROCESSES� AT mGH ENERGIES, EXPERIMENTAL�

Topic

1.� Charged Particle at the ISR

Z.� High Energy pp Charged Particle� Multiplicity Parameters�

3.� KNO Semi -Inclusive Scaling

4.� Evidence for Two Components in High� Energy pp Collisions�

5.� Neutral Pion Production at ISR and NAL

6.� Photon Production at High Energies and� Scaling�

7.� Longitudinal Momentum Distributions� for Protons Produced in pp Collisions� at High Energy�

8.� Measurement of the Inclusive Reaction p + pen) - p + Anything from 15 to 200 GeV/c Using Carbon Target

9.� A Remark About the Fraction of Single� Dissociation�

10. Multiparticle Production in 1I'N Collisions

11 . Cumulative Meson Production in Interactions of Relativistic Deuterons with Nuclei

1 Z. Large Angle Acceptance Experiment at the ISR

13. 1r Production in Inclusive Reactions

14. Strange Particle Inclusive Reactions

1 5. Correlations in Multiparticle Production

Speaker

E ..Linethun (Bergen)

J.� Whitmore (NAL)

P.� Slattery (Rochester)

E.� Malamud (NAL)

K.� R. Schubert (CERN/Hamburg)

L.� R. Sulak (Harvard~

J. C. Sens (FOM. Utrecht)

F. Sannes (Rutgers)

J. VanderVelde (Michigan)

A.� R. Erwin (Wisconsin. Madison)

A.� M. Baldin (Dubna)

G.� Bellettini (Pisa)

K.� C. Moffeit (SLAC)

P.� Soding (DESY)

R.� Panvini (Vanderbilt)

HIGH ENERGY COLLISIONS ill - PRODUCTION PROCESSES AT mGH ENERGIES - EXPERIMENT

Summary prepared by T. Ferbel� University of Rochester�

Rochester, New York�

and

J. Whitmore� National Accelerator Laboratory*�

Batavia, IDinois�

CHARGED PARTICLE PRODUCTION AT THE ISR (#'s 112, 478, 147, 792,900,937,940)

Presented by E. Lillethun� Institute of -Physics�

University of Bergen� Bergen, Norway�

This summary** is not an attempt to show all the detailed data from the experiments but

rather to unify them and to show the gross features they reveal.

The four main experimental teams usually measure charged particle production (11'*# K*, p::l::)

at the standard ISR energies (23.3, 30.4,44.7, and 53.0 GeV) in the following angular regions (the

groups are referred to by their institutions): t

CHLM : 35 mrad < 8 < t80 mrad,ISR2

BCC : -80 mrad < 6 < 350 mrad,ISR3BS : 36· < 8 < 89·,

1SR4 9 -a 0

58: ISR = 90 *1 5 .

The groups have chosen slightly different approaches for the parametrization of their

experiments: S8 always measure at x = 0 and therefore obtain P distributions; as measureT

angular p -distributions which are then converted to P distributions; BCC measure at fixed PT T

= 0.4 Gev/c and for 0.08 < x < O.3Z. and P distributions for x =0.08, 0.16, and O.3Z; and CHLMT

measure PT distributions for fixed x in the range o. f 8 < ·x < 1. Most data refer to P valuesT

between 0.2 and t.2 GeV/c, but the SS group has recently measured ,..* spectra with PT up to

5 GeV/c. Besides the large counter efforts, there are also two smaller groups which have

recently obtained data at the ISR: CERN-Cracow and Bucharest-CERN.

Figure 1 shows E d3aldp3 as a function of P for positive pions created in pp collisions atT

30-GeV c.m. energy. Data are from 58 at x =0, as at x =0, and BeC at x =O.f6. Also shown

*Operate<:l by Universities Research Association. Inc. for the United States Atomic Energy **Commis~ion. . . .

A somewhat more detailed version of this review can be found in E. Lillethun. Charged Parhcle Production at ISR, University -of Bergen Scientific/Technical Report No. 47. November ,1972.

-Ztt ­

are data from CHLM at x =O. t 8 at an energy of 44 GeV and data from Muck et al. S at lower

energy. The main features to note are:

t . The data from S5 and BS show very good agreement and we have consequently not dis­

tinguished between them. However. when fitted to exponential forms the following results are

obtained by the two groups at tJ8 =30.4 GeV:

A B C Ref.3 -Bp

E ~ =Ae T 144±5 5.80:1:0.06 (4) dp3

162~6 6.i8±O.04 (3)

166±iO 6.36%O.Z2 0.48±0.18 (4)

i86±7 6.82±0.12 0.60:tO. fO (3)

Since the coefficients in the fits disagree. one should be very careful when trying to extrapolate

the data, for example to P =O.T

Z. The ISH cross sections are higher than the lower-energy data, showing that scaling has

not quite set in for c. m. energies around 6 GeV. Probably more important is the change in the

shape of the P spectrum from the lower-energy data to ISH-energy data: The spectra showT

essentially the same slope for P ~ 0.3 GeV/c. but below PT =0.3 GeV/c the slope of the lower­T

energy data decreases while there is no apparent change in the ISR data. The average transverse

momentum at ISR energies is therefore lower than at accelerator energies.

3. At x = 0.16 the cross sections are lower than at x =0; slopes in P are essentially theT

same for the two x values at large PT' but the x =0.16 cross section may natten off near PT = 0

just as it appears to flatten in the CHLM data at x -= 0.i8 and ..JS -= 45 GeV.

Figure Z shows a compilation of the 'If± production cross sections for P =0.4 GeV/c as aT

function of

=!. In( EO + Poy _ y . E - PL ) , max 2 E- E+PL

o Po

i. e. ~ the rapidity of the pions measured in the system where one of the protons is at rest. The

data are taken from Refs. t -4 and the solid line represents the data of Muck et a1. 5

It should be pointed out here that the data points scatter by an amount greater than expected

from their statistical accuracy. (No error bars are shown in this or any of the other figures.)

This refiects a difficulty that the experimental teams have to deal with at the ISR, namely that

there are some fiuctuations that are not yet clearly understood.

The following features of Fig. Z are clear: 'a) both 1/ and 11' - spectra show a plateau for

(Ymax -y) ? Z; b) scaling holds from accelerator energies to ISR energies for (Y -y) S 1. max

Figure 3 shows a similar plot for the K::t: cross sections as a function of the rapidity. The

main features here are: a) a plateau essentially as for 'If± but for a shorter range of rapidity,

(Ymax -y) ? Z.S or 3; b) scaling appears to hold better for K+ than for K- production; C) one finds

a factor of roughly 10 between the 'If and K invariant cross sections at P =0.4 GeV/c.T

The p::t: cross sections are shown in Fig. 4 as a function of rapidity. The main features

are:

-ZtZ­

t. The behavior of the proton spectra is very different from the other spectra just shown.

In particular the cross section rises at small rapidities (0 to 0.5), it then decreases by a factor

of to, and remains essentially constant (possibly even increasing) for rapidity values greater than

3. This is shown in more detail for the BS data in Figs. 5 and 6. The large cross section (as

compared to p) is attributed to the leading-particle effects in the fragmentation region.

Z. The cross section scales fairly well at low rapidity values.

3. The antiproton cross sections show a steady rise for increasing rapidities. Related to

this is the observed rise of the p cross section close to y* = 0, as shown for the BS data in Fig.

and 8; although the effect is small, it occurs consistently at each energy.

Figure 9 shows the same cross sections as given in Fig. 4 but for a transverse momentum

P = 0.7 GeV/c. Here the decrease in the forward proton cross sections appears to occur at aT

higher (y -y) value. max +

Figure to shows the 11' cross sections for P = 0.3, 0.5, 0.7, and 0.9 Gev/c at x =0 as aT

function of the center-of-mass energy. 11'- data are also shown for ,JS =6.8 GeV. The rise in

cross section for ,t (and 11' -) is small within the ISR range of energies. It is therefore fair to say

that the asymptotic value has (almost) been reached. (Note that the ratio of 11'+ /11' - = 1.03±O.02 in

this ISH energy region. ) 3 3

The invariant eross sections E d a Idp for p ± at x = 0 and PT = 0.1 GeV Ie are shown in

Fig. 11 as a function of s. The proton cross sections seem to have come down to a plateau at

ISR energies. while the antiproton cross sections are still rising.

Shown in Table I are the multiplicities for each type of charged particle as estimated at

three ISR energies. 7 •8

Table I. Estimated Charged Particle Multiplicities at the ISR. <n > +.J8 (GeV) 11' _'lr__� Ref.~ -L

53 12.0 4.9 4.3 0.7 0.4 0.2 7 11.8 8

45 1t.3 4.6 4.1 0.6 0.3 1.5 0.2

30 10.0 4.1 3.6 0.5 0.3 1.4 0.1

Errors� ±200/0 for 'If± , p

:1:40% for K:I:, P

Finally, Fig. t2 shows the cross section, E d3aldp3, for values ofPT below 5 Gev/c,

x = 0 and rJi = 44.4 GeV. Data are from the SS group. 4 The important remark to be made about

this is the relatively high cross section for high PT values. The deviation from the exponential-6p

fit e� T from lower energies is about a factor of 100 at 5 Gev/c. Between P = 3 and 5 GeV/c,T

the slope, if fitted to e- , is B - 2.5 (Gev/c) -1.BPT

References

1CERN-Holland-Lancaster-Manchester collaboration, M. G. Albrow et 81. #'s 792 and 940.J

2Bologna-CEN/Saclay-CERN collaboration, A. Bertin et aI. J #!s 747 and 936.

3British-Scandinavian collaboration, B. Alper et a1. , #900.

4Saclay-Strasbourg collaboration, M. Banner et al. , #478.

-213 ­

--

SH. J. MUck et ale , Phys. Letters 39B, 301 (1972).�

6CERN-Rome Collaboration, A1labY~ale ~ (-Oxford Conference contribution).�

7A. Bertin et ai., #937.�

aG . Damgaard and K. H. Hansen, *1iZ.�

9 L . G. Ratner et al., Phys. Rev. Letters 1.7, 68 (1971).�

iO M• G. Albrowet al., Phys. Letters 40B, -;-36 (1972), and private communication.

100

0

* 0

•0 :+'iT<l­

,-0"

~* *0

J+~ Oy

10 +o. ¢.

++/¢~ t~

>CD� 0­.a ~~

N I

t ~

t", E

('I)""

a.. ~l

+t~ -c

f<t1b .. ,9~~ "0

t4­11J�

~1

t0.1 H

Symbol Ref. vs(GeV) x-I 53.0 0.18• l

6. 2 30.5 0.16­0 3 30.5 0(90°)

4 30.5 0(90°)•.. 5 6.8 0 + 9 30.5 025

0.01 0 0·2 0.4 0.6 0.8 : 1.0 1.2 1.4

PT", GeV Ie

Fig. i. The invariant cross section for production of 'If+ as a function of transverse momentum. for fixed values of x and different values of t/S-.

-2.t4­

100

,• ~ 9' 11+

10

N

•> ~

<!)

..0

E 10 M

a. I ,."C

"'" b M ."�

W�

Symbol Ref. J$(GeV)

• 1,10 30.5 0 3 30.5.. 4 23.3

30.5 44.7 53.0

7 23.3

•<> V 7 30.5

7 44.7

• 7 53.0

0.' -1 0 2 3 4 5

Y max Y + ­Fig. 2. The invariant production cross section for 11' and 11' at fixed transverse momentum

(P = 0.4 GeV!e) as a function of "laboratory" rapidity, Ymax-Y' The 11' - data are displaced aT

de cade below the 11'+ data for clarity. The plateau in each case is roughly f 3 mb -GeV -2 . The curves represent the data of Ref. 5.

-215 ­

~ ~ft f f ~+ ++ K+

+ +� 1+#++ +

1+1+ N

I

> 4»�

C)�

.a E� ~ ~ +9+ ++

K

"'aa ~ --.. b

(IIJ

"0� UJ�

0.1

o� 1.0 2.0 3.0 4.0 YtnCf'l.-Y

Fig. 3. The invariant production cross section for K+ and K- at fixed transverse momentum (PT =0.4 GeV Ie) as a function of "laboratory" rapidity,y -yo Note the displaced ordinate seiles. The symbols are defined in Fig. 2. The curvesI¥~reBentthe data of Ref. 6.

-216­

20

~ = 0.4 G.V/c 10

p

N I

> ~ .a� E� M~ ~O.1 b PC")

-0 111

Q01­

0.003......----......---.......-----""'-------........� o 1.0 2.0 3.0 4.0 Yma)(- Y

Fig. 4. The invariant production cross section for p and p at fixed transverse momentum (PT =

0.4 GeV Ic) as a function of ''1aboratoryU rapidity~ Ymax-Y' The symbols are defined in Fig. 2.

but the data of Refs. f and fO are at 53.0 GeV and the solid curves are the data of Ref. 6. The dashed curve is the difference between proton and antiproton cross sections and represents proton production via other channels (assuming pair production).

-2f 7­

iii i • • i i •10.� 10r-,---........-r-.....---ri-r-i--..,--,-,�

Protons.-VS =3IGeV Protons.-VS =53 GeV

t --~, 9----§--~, -- " ~ '-,

" ........ 'iIL ~ p. =.3� ~--+---2-- ....""2----~p =.3�---V--" r� N ""...... T ............�T >CDt--+ ............"2-----~.4N ~

(.!) ---~---2--- -2-----~.4

I ~ "­(!)� .c~ t--+----_~ -JI\ 5!}---- r---- ~. ---r __ ~.500 "­� E ~_-~--~~----~---~-x§

1.0 t ---+------~.6 ----~ 6 If)bl~CL -----2----~-- ~.

I .Q

----t ~-------l7 ----_.A 7~bl~~ "0"0 ~u ----y ~.8 W ~ t-----2-----i·8 ~.

"----t.................",2.9 ~---_2_----i .9

~-...... If""I _

II , ...­O.ln 2� 0.10� .2 A

y*

Fig. 5. Invariant cross section for the production of protons at Fig. 6. Invariant cross section for the production of protons at various transverse momenta as a function of the natural ISH various transverse momenta as a function of the natural ISH rapidity (c. m.) at tJB = 31 GeV. Data of Ref. 3. rapidity (c. m.) at ~ = 53 GeV. Data of Ref. 3.

Antiprotons,-VS :53 GeVAntiprotons.-JS =31 GeV

t"~-+f"'---X =3~"-~ ....... ~ .�1.0t:......t--~----i- __--2P =.3 1.0~--2--- t-----2--±!.-l.4N >

I CD T <.!)

t --1---~-----+----~.4

N

t---f--- ------2---J--1 ...0

> Q)

w + __ I -- ~ 6 S~ "­ r--_ - lL y.C)

E ---j----+----- +-----a.S E

.A­

I .0"2----t----X-------§.6J.7

~

~----t---+------~.7rt)blrt)c. ",bl"'a.

"'0 ~

"'C "'C ~----f----~------i' t----t---isI lJJI.LJ

0.1~----t----l.9c­l----t----~·8 I O.lC ...~.9

~--. t;" ,�f ............ -, I�

I I 4 o .2 .6 .8o .2 . y* A y* Fig. 7. Invariant cross section Cor the production of antiprotons. Fig. B. Invariant cross section for the production of antiprotons, at

at various transverse momenta, as a function of the c. m. ISR various transverse momenta. as a function of the c. m. ISR rapidity at ~ =31 GeV. Data of Ref. 3. rapidity at ~ :: 53 GeV. Data of Ref. 3.

10

PT = 0.' GeV/c

+ + ~++ P

N I ; >.. C)

.0 ~ ~.? ¢+ J; E

t'l)c.

" ....... b

t'I) +

t ~ +,.Y

~ t

-c w 0.1 is

0.01 o� 1.0 2-0 3-0

Ymd-.-Y

Fig. 9. Th.e invariant production crOBS section for p and IS' at fixed transverse momentum. (PT = 0.7 GeV Ie) as a function of ''laboratory'' rapidity, Y -yo The symbols are defined in Fig. 2, but the data of Refs. t and to are at 44.7 GeV.

max

-220­

10

+ p + p --. 1T +..... at)( =0

. t·i ~=0.3 GeV/c

• ~

+ 10

0.5 GeV/c ~ + t t~ ~ • -}�0 .Q

E+

i,., .. CL t+ 0.7 GeV/c~

-0 t ~ b •~

"0 W

+ t} 0.9 GeV/c

t~

• +

10

Fig. 10. The invariant production eross sections for 11'+ at x =0 (90· ) and various fixed values of transverse momentum as flDlctions of center of mass energy.[S. -Data of Ref. 3 (0), Ref. 4 (9), and Ref. 5 ( *). Also shown from Ref. 5 are 11' - production data (+).

-221 ­

x=o PT=0.7 GeV Ie

100 • P t +t ~ ~

t t N, ~ >4U t

(!) 10-1� .c� E

Pl""0­

"'C� ...... -0 P

('I")

"'0� W�

10-2

•

10-3 .........-.I.---&----I.......a..-a............~-..........-L....-----...................~----...&....I 2

10 10�

SJ GeV2�

Fig. t t. The invariant cross sections for the production of p and p at x = 0 (90 0 ) and PT =0.7 GeV Ie

as functions of center of mass energy squared. Data of Ref. 3 (0), Ref. 4 (YL and Ref. 6 ( *).

-222­

210

P+P -+1T+ ---­10 X=oVi=".' GeV\:

102 liTI

+ I : TIt t \ _:'JT0

10

i %

\� ~ 'f( \:�

Q) C) 1Ii .0 10-1

\E.. \ tr)

Q. \ 0 -0 \ iT-... 10-2 \ ~

C") \ + '"'C \ II 11w

10 3 \\ II�\� \ I

10-4 \ \ I III

/\

10-5 -6P' \ IIIA.e T \

\ orr III! 10-6 \

\ \ 1 \

10-7

0.0 1.0 2.0 3.0 4.0 5.0 6.0 P1"GeV Ie

Fig. fl. The invariant production cross sections for pions at x= 0 (90") and ~= 44.4 GeV as functions of transverse mom.entum. Data of Ref. 4" The dashed line is an extrapolation of the exponential behavior observed at small PTe Note the displaced ordinates for 11'+ and 11' - •

-223 ­