16O AgBr Interactions Research Articles

Higher order correlation of the pions and their target excitation dependence in relativistic and ultrarelativistic nuclear collisions

The target excitation dependence of higher order correlation of the pions is investigated in the present work using the data of 16O–AgBr interactions at 2.1 and 60 A GeV and 32S–AgBr interactions at 200 A GeV. The data are divided into different sets of ng which correspond to different degrees of the target excitation. The target excitation dependence was evident at the lower projectile energy—at the higher projectile energy no target excitation dependence was revealed by the data.

Intermittency of Target Fragments in 16O–AgBr Collisionsat 4.5 A GeV/c

We report the angular distributions of grey and black particlesproduced in 16O–AgBr interactions at 4.5 A GeV/c in nuclearemulsion. Intermittency and fractal behaviour are studied for emissionspectra of target associated grey and black particles. Intermittentbehaviour is observed for both grey and black particles. In both thecases, anomalous dimensions are seen to increase linearly with theorder of moments, thereby indicating the association of multifractilitywith production mechanism of both grey and black particles.

Target excitation dependence of pion fluctuation in relativistic heavy ion collision at 2.1 and 60 AGeV

This paper studies the dependence of a fluctuation pattern of produced pions on the target excitation for 16O–AgBr interactions at 2.1 and 60 AGeV. For studying target excitation dependence, the data for produced pions are distributed into three sets depending on the number of grey tracks (ng). The different sets correspond to the different degrees of target excitation. We have investigated the fluctuation pattern of emitted pions corresponding to different sets in both η (pseudo-rapidity) and ϕ (azimuthal angle) space. The effective fluctuation strength is calculated for each set for both η and ϕ space. The study reveals that the fluctuation pattern of pions depends on target excitation and the dependence is more pronounced at the lower projectile energy.

Evidence of azimuthal void probability scaling in relativistic and ultra relativistic nuclear interactions

A study of azimuthal angle void probability of produced pions has been carried out in relativistic and ultra relativistic nucleus–nucleus interactions (32S–AgBr interactions at 200 A GeV, 16O–AgBr interactions at 60 A GeV , 24Mg–AgBr interactions at 4.5 A GeV and 12C–AgBr interactions at 4.5 A GeV). The study reveals a very interesting observation-void probability showing scaling behaviour at significantly lower energy (24Mg–AgBr interactions at 4.5 A GeV and 12C–AgBr interactions at 4.5 A GeV) whereas the behaviour is not so pronounced at higher energy in 16O–AgBr interactions at 60 A GeV and the data do not reveal scaling behaviour at all in case of 32S–AgBr interactions at 200 A GeV.

Features of the total disintegration events of heavy emulsion targets caused by 4.5A GeV/c 16 O

Total disintegration events produced by 4.5 A GeV/c 16O–AgBr interactions are analysed to investigate the characteristics of secondary charged particles produced in such collisions. The multiplicity distributions of grey, black, and relativistic charged particles can be well represented by Gaussian distribution. The average multiplicity of grey particles is found to increase with the mass of projectile increasing, while that of black particles is found to decrease with the mass of projectile increasing. This result is in good agreement with the prediction of fireball model. Finally, the linear dependence between grey and black particles is observed, but there is no distinct dependence between the production of relativistic charged particles and the target excitation.

Signature of void probability scaling in jet-like events in 16O–AgBr interactions at 60 GeV/n

This paper presents the analysis of jet-like and ring-like events to study the rapidity gap probability of pions produced in 16O–AgBr interactions at 60 A GeV. The study reveals the scaling behavior of the void probability for the jet-like events. However for ring-like events, the rapidity gap probability does not obey the scaling law.

Pion production and multifractality in ultrarelativistic nuclear collision – evidence of constant specific heat

Multifractal analysis of the pions produced in 32S–AgBr and 16O–AgBr interactions at 200 and 60 AGeV, respectively, is performed following the method proposed by Takagi. The generalized fractal dimensions Dq's are determined and found to decrease with order, thereby supporting multifractality in multiparticle production. From the knowledge of Dq, the multifractal specific heat is calculated for each interaction. It has been observed that the value of the specific heat is independent of the collision energy. PACS Nos.: 25.75–q, 24.60.Ky, 12.40.Ee

Evidence of Intermittent Type Fluctuation of Target Residue in Relativistic Nuclear Collisions at a Few Gev/n

This paper presents evidence of intermittency in target fragmentation in 28Si-AgBr interactions at 14.5 AGeV in emission angle space and azimuthal angle space separately and also in two-dimensional (cos θ,ϕ) space. From the intermittency exponent, the anomalous fractal dimension dq is calculated and the variation of dq with the order q is investigated. The authors also compare the results with those obtained from 16O-AgBr interactions at 60 AGeV and at 2.1 AGeV and 32S-AgBr interactions at 200 AGeV to study the energy dependence of intermittent type of fluctuations in emission angle and azimuthal angle space separately. Comparing the intermittency exponents in one- and two-dimensions it is further seen that intermittency exponent has a higher value in two-dimensional space.

Evidence of Dynamical Fluctuation of Target Residues in Relativistic Nuclear Interaction at 14.5 AGeV

An analysis of data of target fragments of 28Si-AgBr (at 14.5 AGeV) reveals the existence of emission asymmetry in the azimuthal plane, which is found to depend on the number of target fragments. The comparison with the data of 32S-AgBr (at 200 AGeV) and 16O-AgBr (at 60 AGeV) interactions indicates that emission asymmetry depends on the projectile mass and energy.

Search for shock-wave phenomena in central 16O-AgBr interactions at 0.2 and 2.0 GeV/nucleon

Angular distributions of high energy He nuclei, emitted from the target in central 16O-AgBr interactions, are found to be highly forward-peaked at 0.2 GeV/nucleon but almost isotropic at 2 GeV/nucleon. The angular distributions are in qualitative agreement with recent shock-wave calculations. However, we observe no narrow peaks neither in the angular nor in the energy distributions of He nuclei.

Interactions of 2 GeV/Nucleon 16O with Light and Heavy Emulsion Nuclei

Heavy ion interactions in nuclear emulsions induced by 2 GeV/nucleon 16O have been studied. The reaction cross sections determined are 337-85+56 mb, 1007-174+175 mb and 2180-231+304 mb for interactions with H, CNO and AgBr, respectively. Energy-, angular- and transverse momentum distributions of non-relativistic protons (E400 MeV) and all He nuclei have been analysed. Statistical models assuming small correlations among nucleon momenta can account for the main part of the He emission. The energy- and transverse momentum distributions of protons, emitted from light as well as heavy target nuclei indicate that intranuclear nucleon-nucleon scattering is the most important proton emission process. The angular distributions of both high energy protons and high energy He nuclei emitted from the target nucleus differ considerably in central and peripheral 16O-AgBr interactions. In order to explain the angular distributions of high energy protons and He nuclei in events with extremely small impact parameter, non-statistical phenomena, possibly hydrodynamic shock wave emission, must be considered.