Study of multiplicity correlations in nucleus–nucleus interactions at high energy

In the present paper, some results on the correlations of the nucleus–nucleus interactions, at high energy, between different particle multiplicities are reported. The correlations between the multiplicities of the different charged particles emitted in the interactions of 22 Ne and 28 Si nuclei with emulsion at (4.1–4.5)A GeV/c have been studied. The correlations of the compound multiplicity nc, defined as the sum of both numbers of the shower particles ns and grey particles ng, have been investigated. The experimental data have been compared with the corresponding theoretical ones, calculated according to the modified cascade evaporation model (MCEM). An agreement has already been fairly obtained between the experimental values and the calculated ones. The dependence of the average compound multiplicity, on the numbers of shower, grey, black and heavy particles is obvious and the values of the slope have been found to be independent of the projectile nucleus. On the other hand, the variation of the average shower, grey, black and heavy particles is found to increase linearly with the compound particles. A strong correlation has been observed between the number of produced shower particles and the number of compound particles. Moreover, the value of the average compound multiplicity is found to increase with the increase of the projectile mass. Finally, an attempt has also been made to study the scaling of the compound multiplicity distribution showing that the compound multiplicity distribution is nearly consistent with the KNO scaling behavior.

A STUDY OF COMPOUND PARTICLES IN EMULSION

An attempt is made to study the compound particles by taking black and shower particles together. Average compound particle multiplicity is found to vary linearly with heavily ionizing particle multiplicity but with black particle multiplicity it does not show a linear dependence. Dispersion of the compound multiplicity distribution has also been studied. The ratio of the mean number of compound particles to its dispersion for different target sizes has been calculated.

A Study of Pion-Nucleus Interactions in terms of Compound Particles

We report some results on the compound multiplicity distribution at 340 GeV/c π- nucleus interactions. Compound multiplicity distribution is found to depend on the target size and the distribution becomes broader. The peak of the distribution shifts towards higher values of the compound particle multiplicity. Mean compound multiplicity is found to vary linearly with grey, heavy, and shower particle multiplicity. Correlations between different particle multiplicities have been studied in detail. Dispersion of compound multiplicity distributions and its ratio with the mean value is observed to obey a linear relationship with different particle multiplicities except for shower particles where dispersion is almost independent of shower particles. Mean normalized multiplicity has also been studied in terms of created charged particles.

SOME CHARACTERISTICS OF THE COMPOUND MULTIPLICITY IN HIGH-ENERGY NUCLEUS–NUCLEUS INTERACTIONS

The present paper deals with the interactions of 22 Ne and 28 Si nuclei at (4.1–4.5)A GeV /c with emulsion. Some characteristics of the compound multiplicity nc given by the sum of the number of shower particles ns and grey particles ng have been investigated. The present experimental data are compared with the corresponding ones calculated according to modified cascade evaporation model (MCEM). The results reveal that the compound multiplicity distributions for these two reactions are consistent with the corresponding ones of MCEM data. It can also be seen that the peak of these distributions shifts towards a higher value of nc with increasing projectile mass. It may further be seen that the compound multiplicity distributions becomes broader with increasing target size and its width increases with the size of the projectile nucleus. In addition, it has been found that the MCEM can describe the compound multiplicity characteristics of the different projectile, target and the correlation between different emitted particles. The values of average compound multiplicity increase with increasing mass of the projectile. Furthermore, it is observed that while the value of 〈nc〉 depends on the mass number of the projectile Ap and the target mass number At, the value of the ratio 〈nc〉/D(nc) seems to be independent of Ap and At. The impact parameter is found to affect the shape of the compound multiplicity distribution. Finally, the dependence of the average compound multiplicity on the numbers of grey and black particles, and the sum of them, is obvious. The values of the slope have been found to be independent of the projectile nucleus.

FLUCTUATION PATTERN OF SHOWER AND COMPOUND MULTIPLICITY DISTRIBUTIONS IN NUCLEUS–NUCLEUS INTERACTIONS AT A FEW GeV

This work presents a study on the multiplicity distribution of shower and compound multiplicity (pions + target protons) emitted from 12 C – AgBr and 24 Mg – AgBr interactions at 4.5 AGeV in terms of negative binomial distribution (NBD) and also on the fluctuation pattern of shower and compound multiplicity in the frame work of two-dimensional factorial moment methodology using the concept of Hurst exponent.

Self-affine fluctuations of pions and protons and nonthermal phase transition in hadron–nucleus interactions

The paper reports a study revealing self-affine fluctuations in pion, proton, and compound multiplicity (of pions combined with protons) spectra obtained from the interactions of 350 GeV pions with AgBr nuclei. The study is performed in the transformed two-dimensional phase space of the emission and azimuthal angles using the factorial moment methodology and the concept of the Hurst exponent. Evidence of a nonthermal phase transition is obtained for self-affine fluctuations of pions along with an indication for such a regime to be seen in similar fluctuations of proton and compound multiplicity distributions. The study bridges the anisotropic nature of the multiparticle production process and an evidence of the nonthermal phase transition with similar earlier findings from hadron–hadron and nucleus–nucleus interactions and shows the same effects to be peculiar features of the multiplicity distributions of the different species of particles produced. All this brings important information about the underlying dynamics of the hadroproduction process.PACS Nos.: 25.80.Hp, 24.60.Ky, 13.85.–t

Azimuthal asymmetry and dynamical fluctuation of compound multiplicity in nucleus–nucleus collisions at ultra-relativistic energy

The paper reports a study on azimuthal asymmetry fluctuations in compound (pion combined with proton) multiplicity spectra obtained from interactions of 60A GeV 16O–nucleus and 200A GeV 32S–nucleus with AgBr nuclei. The maximum azimuthal asymmetry is investigated, averaged over different compound multiplicity intervals. The data exhibit the existence of a dynamical component in the emission asymmetry fluctuations. The degree of the asymmetry is found to decrease as the multiplicity increases, and the decrease is found to be faster for a heavier projectile. The latter may provide important information on the production mechanism, when compared to the similar studies of pion fluctuations, where no such dependence has been observed. PACS Nos.: 25.75–q, 24.60 Ky

Fractality of emission of compound multiplicity in 12C–AgBr interactions at 4.5A GeV

This paper presents a fractality analysis of the compound multiplicity (pions + target protons) distribution in 12C–AgBr interactions at 4.5A GeV in terms of moments proposed by Takagi (Phys. Rev. Lett. 72, 32 (1994)) for both emission-angle (θ) and azimuthal-angle (ϕ) space. The generalized dimensions Dq, q = 1 to 5, have been calculated and compared to other studies. The analysis reveals the multifractal nature of particle production as a common feature of emission of different patterns in high-energy nuclear collisions. PACS Nos.: 25.75–q, 24.60 Ky