Inelastic interactions caused by 4.5 A GeV/c carbon and silicon nuclei

IL NUOVO CIMENTO VOL. 106A, N. 2 Febbraio 1993

Inelastic Interactions Caused by 4.5A GeV/c Carbon and Silicon Nuclei (*).

TAUSEEF AHMAD and M. IRFAN

Department of Physics, Aligarh Muslim University - Aligarh 202 002, India

(ricevuto il 10 Aprile 1992; approvato il 2 Giugno 1992)

Summary. - - Emission characteristics such as multiplicity distribution, multiplicity correlation, KNO scaling, moments and angular distributions of secondary charged particles produced in 4.5AGeV/c carbon- and silicon-emulsion interactions are investigated. Results obtained in the present study are compared with those reported for different projectiles having the same incident momentum per nucleon.

PACS 25.70.Np - Fragmentation and relativistic collisions.

1 . - Introduction.

The study of nucleus-nucleus interactions at relativistic energies have attracted the considerable attention of high-energy physicists during the recent years due to the realization [1-5] that such studies might provide an opportunity to search for the possible manifestation of the collective properties of high-density nuclear matter and the scale invariance in the collisions of composite systems [6].

With the availability of beams of relativistic heavy ions at the Lawrence Berkeley laboratory (LBL), Berkeley, USA and the Joint Institute for Nuclear Research (JINR), Dubna, USSR, it has become possible to investigate the characteristics of heavy-ion collisions at relativistic energies. Until recently, nucleus-nucleus collisions were considered to be a rather complex affair owing to the complicated nature of the interactions and due to the fact that theoretical models to explain the experimental data did not exist. However, with the commissioning of heavy-ion accelerators during the last two decades, many new and important developments have taken place in high-energy heavy-ion physics.

The mechanism of multiparticle production of secondary particles in relativistic heavy-ion collisions is believed to be similar to that of hadron-hadron and hadron- nucleus interactions at high energies. By analysing nucleus-nucleus interactions one may also be able to obtain useful and interesting information about the behaviour of nucleons interacting collectively at relativistic energies. Furthermore, from such

(*) The authors of this paper have agreed to not receive the proofs for correction.

1 2 - ll N~ovo Cimetdo A 171

172 TAUSEEF AHMAD and M. IRFAN

studies one may be able to investigate the nature of highly compressed phases of nuclear matter. It may be interesting to mention that currently the high-energy nucleus-nucleus collisions are perhaps the only source to subject the nuclear matter to such abnormal conditions.

In this paper, results on the general characteristics of the interactions caused by carbon (12C) and silicon (2sSi) nuclei of primary momentum 4.5 GeV/c per nucleon with emulsion nuclei are presented. Results obtained from the study of the interactions caused by other projectiles having the same beam momentum per nucleon are also presented. Furthermore, the multiplicity distributions, correlations among various multiplicity parameters, moments of relativistic charged-particle multiplicity, KNO scaling and angular distributions of secondary charged particles are examined.

2. - E x p e r i m e n t a l d e t a i l s .

Two stacks of BR2 emulsion of dimensions (18.6 • 9.5 x 0.06)cm 3 and (16.9 • 9.6 x x 0.06)cm 3, exposed to 4.5A GeV/c 12C and 2SSi beams at the Dubna Synchrophasotron, USSR, have been used in the present investigation. The plates were scanned using a Nikon Microscope having travelling stage. The tracks were picked up at a distance of 3 mm from the entrance edge of the stack and were followed backward to ensure that they did not come from the previous interactions. All such tracks were followed until they interacted or left the stack. Scanning was performed by three independent observers to increase the scanning efficiency; efficiency was found to be -98%.

Random samples consisting of 852 and 1024 events produced in 12C- and 2SSi-emulsion interactions were collected under 15 • eye-pieces and each interaction was looked into under 95• oil immersion objectives for various measurements. Furthermore, the events which satisfied the following criteria were selected:

i) All the beam tracks having projected angles > 3 ~ with respect to the mean primary direction were rejected.

ii) The events produced within 301zm from the top and the bottom of the emulsion pellicles were not included for the analysis.

Secondary charged particles produced in each interaction were classified into shower, grey, black and projectile fragments on the basis of their specific ionization.

a) Shower tracks: Tracks having ionization g < 1.4go, where go represents the plateau density of a singly charged particle, have been classified as shower tracks. The number of shower tracks produced in an event is denoted by Ns ; shower tracks are mostly relativistic pions.

b) Grey tracks: Tracks having ionization in the interval 1.4g0 <~ g <~ 10g0 are termed as grey tracks. Grey tracks are mainly due to protons, deuterons, tritons and some slow mesons. The number of grey tracks in an interaction is represented by Ng.

c) Black tracks: Tracks with ionization g > 10go are defined as black tracks. Black tracks are due to slow and evaporated fragments. The number of black tracks produced in an event is denoted by Nb.

I N E L A S T I C INTERACTIONS CAUSED BY 4.5A GeV/c CARBON AND SILICON N U C L E I 173

Grey and black tracks together are referred to as heavily ionizing particles or heavy tracks in an interaction and their number is denoted by Nh (= Ng + Nb ). It may be noted that grey and black tracks having dip angles, 0,1 <~ 30 ~ are only considered in the present study. To account for the loss of grey and black tracks having dip angles 0d > 30 ~ a statistical weight factor, K, defined below, was assigned to each grey and black track having 0 d ~ 30~

(1) K = Z/2 arc sin (sin 30~ 0) '

K = 1 for the space angles lying in the interval 150 ~ ~< 0 < 30 ~

d) Projectile fragments: Tracks with ionization g ~> 4go (with no change in the ionization over a distance of 2 cm from the interaction vertex) and lying in a narrow cone in the forward direction (0 ~< 5 ~ are known as the projectile fragments. These tracks were not considered for determining the emission characteristics of grey and black tracks.

3. - Multiplicity of secondary particles.

Particle multiplicity defined as the number of particles produced in an interaction is considered to be an important parameter because its study is likely to yield significant information about the production mechanism. However, most of the detecting devices record only the charged particles that are produced. Multiplicity is also regarded as a useful parameter in the study of multiparticle production process in heavy-ion collisions. It also serves as one of the sensitive tools for checking the predictions of different phenomenological and theoretical models.

30

e~

20

10 i

5 l o 15 20 25 - 35 '% Ng

Fig. 1. - Multiplicity distribution of grey tracks emitted in ..... p-, - - - 2sSi-emulsion interactions at 4.5AGeV/c.

~X-, . . . . . 12C- and - -

174 T A U S E E F A H M A D and M. I R F A N

3"1. M u l t i p l i c i t y d i s t r i b u t i o n s . - Multiplicity distributions of grey, black, shower and heavily ionizing tracks produced in 12C- and 28Si-emulsion interactions at 4.5AGeV/c are compared with the corresponding distributions obtained for p-emulsion[7] and a-emulsion[8] interactions at the same momentum per nucleon; these distributions are shown in fig. 1-4. It may be seen in fig. 1 that the Ng-distributions in 12C- and ~sSi-emulsion interactions are appreciably enriched by the events of relatively higher multiplicities as compared to those observed in the ease of p- and ~-emulsion interactions at the same incident momentum per nucleon.

2O

~o

~10

i

?]

-7

5 10 15 20 25 30 Nb

35

Fig. 2. - Multiplicity distribution of black tracks produced in ..... p-, - - - 2sSi-emulsion interactions at 4.5A GeV/c.

, - . . . . 12C- and - -

40

30

t ~

2C

10[ r~, i_~

', ~l r~.

o 5 lo 15 20 25 ao a5 4o Ns

Fig. 3. - Multiplicity distribution of shower tracks produced in . . . . . p-, - - - ~2C- and - - 2sSi-emulsion interactions at 4 . 5 A G e V / c .

INELASTIC INTERACTIONS CAUSED BY 4.5A G e V / c CARBON AND SILICON NUCLEI

15

175

10

~ 5

r

~ . ~ . _ ! , , r 7

5 10 15 20 25 30 35 40 45 50 Nh

Fig. 4. - Multiplicity distribution of heavily ionizing part icles emit ted in . . . . . p-, - - - 12C- and - - 2sSi-emulsion interactions at 4 .5AGeV/c .

However, from fig. 2 it is noticed that the Nb-distributions remain the same for all the four projectiles considered. The Ns-distributions, plotted in fig. 3, shows that the shape of the distribution changes appreciably with increasing projectile mass; with increasing projectile mass the distribution tends to become broader. The number of events with comparatively lower values of Ns decreases with increasing projectile mass. In fig. 4, small dips in the Nh-distributions are observed for 12C- and 2SSi-emulsion events at Nh = 2, 3. It is interesting to mention that a similar behaviour has been observed by Chernov et al. [9] in their study of Nh distribution for 14N-emulsion interactions at 2.1A GeV/c.

3"2. M e a n m u l t i p l i c i t y . - Mean multiplicities of the charged secondary particles for both r~c- and 28Si-emulsion interactions at 4.5A GeV/c are listed in table I, along

TABLE I. - Mean multiplicities of different charged secondaries emitted in nucleus-nucleus collisions for different projectiles at various momenta per nucleon.

Momentum / Project i le <Ng > <Nb } <Ns > Ref. A (GeWc)

4.5 p 2.81 _+ 0.06 3.77 _+ 0.08 1.63 _+ 0.02 [7] 3.6 d 2.34 _+ 0.07 5.78 _+ 0.15 3.08 _+ 0.05 [10] 3.6 ~ 4.64 -- 0.17 4.68 _+ 0.15 3.86 -+ 0.08 [10] 4.5 a 4.70 _+ 0.20 4.70 + 0.20 3.90 -+ 0.10 [8] 4.5 C 5.93 -+ 0.34 4.49 -+ 0.24 7.67 -+ 0.19 (*) 2.1 N 5.29 _+ 0.31 4.57 -+ 0.22 8.85 -+ 0.28 [9] 4.5 0 7.60 -+ 0.60 4.88 -+ 0.29 10.50 _+ 0.60 [12] 4.1 Ne 7.58 -+ 0.23 7.63 -+ 0.17 8.38 -+ 0.22 [11] 4.5 Si 8.59 _+ 0.26 4.69 _+ 0.23 11.26 _+ 0.33 (*)

(*) Present work.


with the results reported by other workers [7-12] involving different projectiles at various incident momenta per nucleon. The average multiplicity of the singly charged relativistic particles grows rapidly with increasing mass of the incident nucleus. This behaviour is compatible with the predictions of the superposition models [13-15]. It may also be seen from table I that <Ng> increases with increasing projectile mass. This trend can be explained in terms of the predictions of the fireball model [16]; this model predicts that the number of the participant nucleons should increase due to increasing volume of the cylinder cut in the target by the projectile. Thus volume increases with increasing mass of the projectile and consequently the average number of the grey particles should increase. The value of <Ng > within the stated errors is observed to be independent of the mass of the projectile as well as the momentum of the incident nucleus.

^ '

I I

i0 ~ 101 m a s s n u m b e r (A)

10 2

Fig. 5. - Average multiplicities of �9 shower, �9 grey and �9 black tracks as a function of the projectile mass. The solid lines shown in the figure are discussed in the text.

Variations of <N~ >, <N~> and <Nb> with projectile mass at 4.5A GeV/c are shown in fig. 5; the solid lines in the figure can be represented by the following equation:

(2) <Nx > = constA ~,

where x represents shower or grey or black particles. The best fitting values of ~ are 0.61 _+ 0.04, 0.33-+ 0.02 and 0.06-+ 0.02, respectively, for the variations of the average numbers of shower, grey and black particles with the projectile mass. From fig. 5, it is seen that (Nb> and <N~> depend weakly on the projectile mass in comparison with the dependence of <Ns > on the projectile mass. However, in general one may conclude that the larger the momenta of the secondary particles emitted in heavy-ion collisions, the stronger the projectile mass dependence of the average particle multiplicities is.

Figure 6 shows the variations of D/(Ns > with the number of the grey tracks for 12C- and 2sSi-emulsion collisions, where D represents dispersion defined as [(<N~>- -<Ns>2) 1/2 ]; D/<Ns> varies with Ng in the following fashion:

(3) D/<Ns > = a(Ng)b ;

INELASTIC INTERACTIONS CAUSED BY 4.5A GeV/c CARBON AND SILICON NUCLEI 177

1.0

carbon

05

~ , silicon

0.5

0 1'0 2'0 3'0 Ng

A

5 o V l 0

Fig. 6. - The ratio D(N~)/(N~} as a ihnction of the number of grey tracks.

the values of a and b are found to be 0.834 _+ 0.127, - 0.352 _+ 0.051 and 1.081 + 0.117, - 0 . 4 9 7 - 0.072, respectively, for 12C- and 2sSi-emulsion collisions. It may be noted that D/<Ns> decreases with increasing Ng. This result is at odds with the predictions of the collective tube model [17] and favours the model which takes into account the repeated collisions [18]. It may be of interest to mention that the collective tube model predicts that D/<Ns} shall remain constant with N~. Similar results have also been obtained in the case of proton- and pion-nucleus interactions[19] at high energies.

3"3. Multiplicity correlations. - Several authors[7,19-21] have attempted to investigate the multiplicity correlations of the type <Ni (N i)>, where N~, Nj = N~, Nb, Nh, Ns with i ~ j, over widely different incident energies using different projectiles. We have also attempted to study the multiplicity correlations for three projectiles--p, 12C and 2sSi; these correlations have been nicely fitted by using the linear relation

(4) (Ni(Nj)> = at] + bijNj (i ~ j)

in the full range of Ni variation except for (Nb } - Ng and (Ng > - Nb correlations which have been observed to be non-linear ones. In fig. 7, the variations of <Nb>, (Ng) and (Nh > with N~ are shown for all the three projectiles, whereas in fig. 8 the variations of (N~ > with Ng, Nb and Nh are shown for the three projectiles at 4.5A GeV. From these figures it follows that:

i) in the case of p-emulsion interactions there is practically no dependence of (N~ >, (Nb > and (Nh > on Ns, meaning that the number of shower particles produced in

15f , 0 | .pr~176 ~ ~ ]1 ~[

i i , ,

0 2 4 6

30

2O

10

V

V 40

30

20

10

carbon ~

I'0 2'0

0 0

io

A

silicon , I / ~

10 20 30 40 50 Ns

30

20

10

0

36

24

12

0

40

32

24

16

10 20 30 40 50 Nh

Fig. 7. Fig. 8.

J

Nb

Ng


Fig. 7. - Multiplicity correlations of • (Nb), �9 (Ng) and �9 (Nh) with Ns, for p-, 12C- and 2sSi-emulsion interactions.

Fig. 8. - Multiplicity correlations of (N~} with Nb, Ng and Nh, for �9 p-, A 12C- and �9 28Si-emulsion interactions.

an event is independent of the target excitation. But in the case of 12C-emulsion interactions these parameters, (Ng }, (Nb) and (Nh }, are observed to depend strongly on Ns. A similar trend is visible in the case of 2sSi-emulsion collisions.

ii) There are negative correlations of (Ns} with Ng and Nb in the case of p-emulsion interactions, whereas in the case of 1~C- and 2sSi-emulsion reactions, the correlations are strong and positive. Consequently, the variation of (N~) with the number of heavily ionizing particles in the case of p-emulsion interactions is weak and negative. However, in the case of heavy-ion collisions, for example, 12C- and 2sSi-nucleus collisions, the variations are moderate and positive. On the basis of these observations, it may be stated that the absorption of shower particles is relatively higher than the multiplication during the propagation through the nuclear matter in p-emulsion interactions. The values of the parameter b~j for the above correlations are listed in table II. It is observed from the table that the variations of the values of (Ns)

INELASTIC INTERACTIONS CAUSED BY 4.5A G e V / c CARBON AND SILICON NUCLEI 179

TABLE II. - Values of the slope coefficients in multiplicity correlations in proton-, carbon- and silicon-emulsion interactions.

Project i les (N~) (Ng) (Nb) (Nh)

N~ p - 0.01 __ 0.04 0.02 _+ 0.02 0.03 -+ 0.04 C 0.45 +_ 0.01 0.32 ~+ 0.01 0.75 - 0.02 Si 0.55 _+ 0.03 0.53 _+ 0.05 1.13 _+ 0.07

Ng p - 0.10 +_ 0.01 C 0.55 -+ 0.03 Si 1.17 _+ 0.12

N b p - 0.02 _+ 0.01 C 0.49 _+ 0.03 Si 0.84 _+ 0.09

Nh p - 0.03 _+ 0.01 C 0.32 _+ 0.01 Si 0.81 _+ 0.02

15

lO

V

20

A

V

10

Nb

0 10 10 3'0 40 Ng

Fig. 9. - Multiplicity correlat ions of {N~,) with Ng and (Ng) with Nb for �9 p-, A 1~C- and �9 zsSi-emulsion interactions.


with Ng, Nb and Nh are comparatively faster for 2sSi-emulsion interactions in comparison with the corresponding variation observed for 12C-emulsion interactions.

Variations of (Nb) with Ng and of (Ng) with Nb are plotted for p-, 12C- and 2sSi-emulsion interactions at 4.5A GeV in fig. 9. It may be seen in the figure that the (Ng) - Nb correlation gets saturated around Nb -- 12 for p-nucleus collisions and Nb

16 for the heavy-ion reactions. Furthermore, the ( N b ) - Ng correlation saturates beyond Ng = 16 for 12C- and 2sSi-emulsion interactions. However, in the case of p-nucleus collisions, the (Nb) - Ng correlation does not saturate. Similar results have also been obtained by Stenlund and Otterlund[22] for proton- and pion-nucleus collisions over a wide range of incident energy. It has been pointed out by these authors [22] that the saturation in these correlations should occur because the energy of the struck nucleus becomes so large that there is no way to dispose it off except by undergoing complete destruction. In such a situation, it is expected that:

i) the emitted products may have higher energies than the particles likely to be produced through the evaporation process, which in turn would result in the increase of the grey-particle multiplicity and

ii) relatively heavier fragments might be produced during the evaporation process, thereby causing a decrease in the multiplicity of the black tracks. It means that the ( N g ) - Nb and ( N b ) - N~ correlations are essentially insensitive to the projectile mass in the case of nucleus-nucleus collisions.

3"4. Mul t ip l i c i t y scaling. - During the recent years, many attempts [23-26] have been made to study the multiplicity distribution of charged shower particles produced in proton-proton (p-p), proton-nucleus (p-A) and nucleus-nucleus (A-A) collisions[20,27]. It has been observed that the probability distribution for the production of n relativistic charged particles exhibits a universal behaviour for all interactions--p-p, p-A and A-A. Hence one may express (n )P , = ,~(n/(n)), where P , is the probability of production of n charged particles, (n} represents the average number of charged particles and ~ is some function of the variable, Z (= n/ (n) ) . This behaviour of the multiplicity distribution as a function of the variable Z is referred to as KNO scaling after Koba-Nielsen-Olesen[28]. The probability of observing n charged particles in p-p interactions is related to the scaling function 4~(Z) as [28]

( 5 ) p , , _ o . _ ( n ) - i ~ ( n / ( n ) ) = (n) - i ~(Z), ~'inel

where ~ and ~'inel are the partial cross-sections for producing n charged particles at a given centre-of-mass energy Vs and the total inelastic cross-section, respectively.

Slattery [29] has proposed the following form for the scaling function:

(6) r = ( A Z + B Z 3 + CZ 5 + D Z T ) e x p [ - E Z ] ,

where A, B, C, D and E are constants. The values of these constants have been evaluated by Slattery [29] for p-p interactions in the energy range - (50 + 303)GeV; the values of the constants A, B, C, D and E obtained by Slattery are 3.79, 33.7, - 6.64, 0.33, - 3.04, respectively.

INELASTIC INTERACTIONS CAUSED BY 4.5A GeV/c CARBON AND SILICON NUCLEI

1.0

181

o.5

1 2 3 4 Z

Fig. 10. - ~(Z) vs. the scaling function Z/'or carbon (• and silicon (e) projectiles. The solid curves represent the KNO-type scaling function.

Martin et al. [30] have, however, observed that the charged-shower-particle multiplicity for p-emulsion interactions obeys a KNO type of scaling instead of an exact KNO scaling. Martin et al. [30] have expressed the scaling function ~(Z) as

(7) ~m ( Z ) -- (6.84Z + 26.6Z 3 - 2.12Z ~ + 0.16Z 7) exp [ -3 .28Z],

where ~bm (Z) is the modified scaling function. The validity of the KNO scaling at different projectile energies has been debated

by many authors having diverse opinions[31]. Recently, some authors[20, 27] have attempted to examine the existence of the KNO-type scaling in nucleus-nucleus collisions.

A plot of ~(Z) vs. N~/<Ns ), where <Ns ) is the average number of the charged shower particles produced in 12C- and 2sSi-emulsion interactions, is shown in fig. 10. The solid curve in the figure is fitted with the following KNO-type scaling function:

(8) r = (4.38Z + 1.50Z 3 + 0.09Z 5 + 0.03Z 7 ) exp [ - 2.70Z]

with zZ/d.f. = 0.10, where d.f. represents the degrees of freedom. The values of the parameters appearing in eq. (8) have been computed with the help of the CERN standard programme MINUIT.

3"5. Moments of the mult ipl ici ty distribution. - The central moment of the multiplicity distribution is defined as

(9) q ~ q = q V < ( N s - < N ~ ) ) q ) ,

where q = 2, 3, 4, etc. The values of the central moments of the relativistic charged particles for p-, 12C- and 2sSi-emulsion interactions are given in table III. It is noticed from the table that the values of the central moments (2 ,V~2, 3 ~ :~ and 4 V~4) depend strongly on the projectile mass. Incidentally, these results are in fine accord with the predictions of the coherent tube model [32].

1 8 2 TAUSEEF AHMAD and M. IRFAN

TABLE III. - Moments of the multiplicity distribution of relativistic particles produced in proton-, carbon- and silicon-emulsion interactions.

Proton Carbon Silicon

<N~> 1.63 _+ 0.02 7.67 _+ 0.19 11.26 _ 0.33 2 ,V~.z 1.08 _+ 0.02 5.53 _+ 0.13 10.70 _+ 0.24 3 ,V~3 0.98 _ 0.01 5.28 _+ 0.13 11.68 _ 0.26 4 ~ 1.50 _ 0.02 7.47 _+ 0.18 15.20 _+ 0.34 C2 1.44 +_ 0.14 1.52 + 0.16 1.60 _+ 0.12 C3 2.55 _+ 0.17 2.89 _+ 0.08 2.84 +_ 0.06 C4 5.97 _ 0.46 6.23 +_ 0.07 6.21 + 0.06

The normalized moments of the relativistic charged particles are defined as

(10) Cq = <N~ q >/<Ns >q,

where <N~/= Ns~,/~inel is the q-th moment of the shower particle multiplicity distribution, ~ represen ts the partial cross-section for producing n charged particles and ~,el is the total inelastic cross-section.

The values of C2, C~ and C4 for the three types of interactions are listed in table I I I . The values of these moment s are observed to be constant within their statistical limits.

3"6. Angular distributions of secondary particles. - The angular distributions of black, g rey and shower t racks produced in the interactions of 12C and 2sSi ions with emulsion nuclei at 4 . 5 A G e V / c are displayed in fig. 11-13. These distributions are compared with the corresponding distribution for z-emulsion [8] interactions at the same incident momen tum per nucleon. The analysis of these distributions leads to the following conclusions:

ii the angular distribution of black t racks shows a relatively b roader peak around 0 ~ (30 + 60) ~ Similar t rends have been observed by Heckman et al. [33] in the angular distributions of the t a rge t f ragments for 1~0- and 4~

7

6

~ 5

~4 ~ 3 ~u

2

1

0

.... r~

: : : r , . . :

cos Ob

Fig. 11. - Angular distribution of black tracks producc(I in . . . . . ~-, . . . . . 2sSi-emulsion interactions at 4.5A GeV/c.

1~C- and - -


16

14

12

~ 6

?... ,...

cos Og

Fig. 12. - Angular distribution of grey tracks produced in . . . . . a-, 2sSi-emulsion collisions at 4.5AGeV/c.

5 10

r

09 8

4 ~.,[~

~ -~?_ --" 0

COS Os

Fig. 13. - Angular distribution of shower tracks produced in . . . . . ~-, - - - 2sSi-emulsion collisions at 4.5AGeV/c.

12C- and - -

12C- and - -

collisions. I t may be noted that some authors [34, 35] are of the opinion that this t rend is due to the effect of the sideways collective fluk of the nucleons; sideway flow is expected in the hydrodynamical approach for the low-energy fragments.

ii) The angular distributions of grey and shower tracks depend on the projectile mass. However, the forward peaking tends to increase with increasing projectile mass.

4 . - C o n c l u s i o n s .

On the basis of the results of the present investigation, the following important conclusions may be drawn.


1) The multiplicity distributions of shower, grey and heavily ionizing particles and their mean multiplicities depend on the projectile mass, whereas the distribution of black tracks and their mean multiplicity do not depend on the projectile mass and the incident momenta per nucleon.

2) There is no significant difference between the multiplicity correlations of the particles produced in 12C- and 2sSi-emulsion collisions. However, one can say that the variations of the mean shower particle multiplicity with the heavy-, grey-, and black-track multiplicities are faster in the case of 2sSi-emulsion interactions in comparison to those obtained for 12C-emulsion collisions. But the correlations in the case of p-emulsion interactions are often different from those of nucleus-nucleus collisions.

3) The <Ng>-Nb and <Nb > - Ng correlations are observed to saturate beyond Nb(Ng) ~- 16.

4) The KNO type of scaling behaviour is observed in heavy-ion collisions.

5) The central moments of the shower particle multiplicity distribution increase linearly with increasing mean multiplicity. However, the normalized moments are found to be essentially independent of the mean multiplicity and the projectile mass.

6) The angular distributions of grey and shower tracks depend on the projectile mass, whereas the angular distribution of black tracks is independent of the projectile mass.

REFERENCES

[1] H. H. HECKMAN: Invited talk at V International Conference on High Energy Physics and Nuclear Structure, Uppsala, 1973.

[2] A. M. BALDIN: Invited talk at VI International Conference on High Energy Physics and Nuclear Structure, Los Alamos and Santa Fe, 1975.

[3] T. D. LEE: Rev. Mod. Phys., 47, 267 (1975). [4] G. BYAM and S. A. CHIN: Phys. Lett. B, 62, 241 (1976). [5] J. BOGUTA: Phys. Lett. B, 109, 251 (1982). [6] J. I. KAPUSTA: Nucl. Phys. B, 148, 461 (1979). [7] A-ABDDKLMTU-B COLLABORATION: Z. Phys. A, 302, 133 (1981). [8] DGKLMTW COLLABORATION: JINR Dubna communication, P1-8313 (1974). [9] G. M. CHERNOV, K. GULAMOV, U. G. GULYAMOV, S. Z. NASYROV and L. N. SVECHNIKOVA:

Nucl. Phys. A, 280, 478 (1977). [10] E. S. BASOVA, G. M. CHERNOV, K. G. GULAMOV, C. G. GULYAMOV and B. G. RAKHIMBAEV:

Z. Phys. A, 287, 393 (1978). [11] B. P. BANNIK, A. EL-NAGHY, S. A. KRASNOV, G. S. SHABRATOVA and K. D. TOLSTOV: Z.

Phys. A, 329, 341 (1988). [12] V. A. ANTONCHIK, V. A. BAKAEV, A. V. BELOUSOV, S. D. BOGDANOV, V. I. OSTROUMOV and

M. V. PAVLOVETS: Soy. J. Nucl. Phys., 39, 774 (1984). [13] A. BIALAS, W. CzYz and W. FURMANSKI: Acta Phys. Pol. B, 8, 585 (1977). [14] A. CAPELLA and Y. TRAN THAN VAN: Phys. Lett. B, 93, 146 (1980). [15] K. KINOSHITA, A. MINAKA and H. SYMYOSHI: Prog. Theor. Phys., 61, 165 (1979). [16] J. GOSSET, H. H. GUTBROD, W. G. MEYER, A. M. POSKANZER, A. SANDVAL, R. STOCK and

G. D. WESTFALL: Phys. Rev. C, 16, 629 (1977).


[17] S. A. AziMov, G. M. CHERNOV, K. G. GULAMOV, V. SH. NAVOTNY and N. S. SCRIPNIK: Phys. Lett. B, 73, 339 (1978).

[18] I. OTTERLUND: Report LUIP 7904 (1979). [19] TAUSEEF AHMAD, M. TARIQ, M. IRFAN, M. ZAFAR, M. Z. AHSAN and M. SHAFI: Acta Phys.

Pol. B, 20, 701 (1989). [20] D. GHOSH, J. RoY and R. SENGUPTA: Nucl. Phys. A, 468, 719 (1987). [21] V. S. SHUKLA, K. B. BHALLA, A. GILL, V. KUMAR, S. LOKNATHAN, S. MOOKERJEE, A.

BHASIN, V. K. GUPTA, S. KITRO0, V. KUMAR, L. K. MANGOTRA, N. K. ROA, M. M. AGGARWAL, R. ARORA, V. S. BHATIA, M. KAUR and I. S. MITTRA: Mod. Phys. Lett. A, 3, 1753 (1988).

[22] E. STENLUND and I. OTTERLUND: Nucl. Phys. B, 198, 407 (1982). [23] F. FUMURO, R. AHARA and T. OGATA: Nucl. Phys. B, 152, 376 (1979). [24] TSAI-CHU et al.: Lett. Nuovo Cimento, 20, 25 (1977). [25] M. M. AGGARWAL, J. M. KOHLI, I. S. MITTRA, J. B. SINGH, P. M. SOOD, B. BHOWMIK, P. K.

SENGUPTA, S. SINGH, K. B. BHALLA, M. CHOUDHARI, S. LOKNATHAN, S. K. BADYAL, V. K. GUPTA, G. L. KAUL, B. KOUR, Y. PRAKASH, N. K. RAO, S. K. SHARMA and G. SINGH: Nucl. Phys. B, 131, 61 (1977).

[26] A. SHAKEEL, H. KHUSHNOOD, M. IRFAN, M. ZAFAR, V. ALI and M. SHAFI: Phys. Scr., 29, 435 (1984).

[27] P. L. JAIN and G. DAS: Phys. Rev. D, 24, 1987 (1981). [28] Z. KOBA, H. B. NEILSON and P. OLESEN: Nucl. Phys. B, 40, 317 (1972). [29] P. SLATTERY: Phys. Rev. Lett., 29, 1624 (1972). [30] J. W. MARTIN, J. R. FLORIAN, L. D. KIRKPATRICK, J. J. LORD and R. E. GIBBS: Nuovo

Cimento A, 25, 447 (1975). [31] J. HUFNER and B. LIU: Z. Phys. C, 27, 283 (1985). [32] Y. AFEK, G. BERLAD, A. DAR and G. EILAM: Proceedings of Topical Meeting on

Multiparticle Production, Trieste, 1976. [33] H. H. HECKMAN, H. J. GRAWFORD, D. E. GREINER, P. J. LINDSTROM and L. W. WILSON:

Phys. Rev. C, 17, 1651 (1978). [34] H. STOCKER, J. A. MARUHN and W. GREINER: Phys. Rev. Lett., 44, 725 (1980). [35] H. STOCKER, C. RIEDEL, Y. YARIV, L. P. CSERNAI, G. BUCHWALD, G. GRAEBNER, J. A.

MARUHN, W. GREINER, K. FRANKEL, M. GYULASSY, B. SCHURAMANN, G. WEASFALL, J. D. STEVENSON, J. R. NIX and D. STROTTMAN: Phys. Rev. Lett., 47, 1807 (1981).

Inelastic interactions caused by 4.5 A GeV/c carbon and silicon nuclei

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