Multiplicity Of Grey Particles Research Articles

Studies of fast protons produced in the reactions of 16O Nuclei incident on emulsion nuclei at 3.7A GeV

• The grey particle multiplicity characteristics, reflects the role of the limiting fragmentation hypothesis. • It is found that the multiplicity distribution of grey particle is independent of the projectile energy or its size. • The multiplicity distribution P(Ng) of the emitted g-particles fit well with the Gauss distribution function, which is both symmetric and platykurtic behavior. Both values of Skewness (S) and Kurtasis (K) are less than zero. • The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event. We report the experimental data of the fast target protons produced in the reaction of 16 O-Em at 3.7A GeV. The emission mechanism of the fast target protons (grey particles with kinetic energy in the range of 26 – 400 MeV) is investigated in terms of multiplicity characteristics. Our experimental data is compared with the corresponding data from the interactions of 12 C, 22 Ne and 28 Si projectiles at nearly the same incident energy. It is found that the multiplicity distribution is independent of the projectile energy or its size. The interaction events were classified in two ways. First, according to the degree of their centrality, depending on the number of the nucleons remaining as spectators Q (stripping nucleons) from the projectile. The second way, the interactions are classified according to the target size (N h – parameter). At various groups of events, the higher moments of the multiplicity distributions were calculated statistically. The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event.

Characteristics of the grey particles emission at relativistic energy

The theme of present analysis is to focus on the emission characteristics of grey particles emitted in 4π angle, forward hemisphere angle (θ < 90°) (FHS) and backward hemisphere angle (θ ≥ 90°) (BHS). We have studied the average multiplicity variation of grey particles for the events emitted from the reaction of projectiles with CNO and AgBr target nuclei of nuclear emulsion. We have also investigated the emission probability of grey particles with projectile mass in between the range of 1 and 207. In this analysis we have observed that the emission probability of grey particles is higher in forward hemisphere angle as compared to backward hemisphere angle. We have also observed that the average multiplicity of grey particles is independent on the projectile mass and incident energy.

Centrality dependence of total disintegration of target nuclei in high energy nucleus–nucleus interactions

A study of centrality dependence of target fragmentation and multiparticle production has been carried out in 16O–AgBr, 22Ne–AgBr, and 28Si–AgBr interactions at 4.1–4.5 AGeV/c for the total disintegrated (TD) events. Average multiplicity of black particles increases linearly with decreasing centrality while average multiplicity of grey and shower particles decreases with decreasing centrality for the TD events. The decrease of average multiplicity of grey particles is linear; on the other hand, in the case of shower particles, the increase is nonlinear. With the increase of the mass of the projectile beam, the average multiplicity of black particles decreases and the average multiplicity of grey particles increases for the TD events. This observation has been explained on the basis of the fireball model; however, in the case of shower particles, average multiplicity increases with increase of projectile mass.

Sensibility of grey particle production system to energy and centrality in 60A and 200A GeV 16O–Nucleus interactions

The grey particle production following 60 A and 200[Formula: see text]A GeV [Formula: see text]O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4[Formula: see text] space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

Complete Destruction of Ag Br Emulsion Nuclei BY&amp;lt;sup&amp;gt;28&amp;lt;/sup&amp;gt;Si Ions with 4.5 GeV/Nucleon Energy

The main experimental characteristics (multiplicity characteristics) of secondary particles have been investigated in interactions of 28Si with emulsion at 4.5 GeV/c per nucleon at rest of emulsion, nuclei. The complete destruction of the heavy target nuclei (Ag, Br) has been studied. The average of shower particles s > is weakly dependent on the target mass whereas the average multiplicity of grey particles g > is strongly dependent on it. The correlations between the multiplicities of the charged secondaries at different mass number of the projectile and center-of-mass-available energy are investigated.

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.

Angular characteristics of charged shower particles in 4.5A GeV12C-nucleus interactions

A study of angular characteristics of charged shower particles in terms of pseudorapidity, η, has been carried out by analyzing the experimental data obtained in 4.5 A GeV12C-emulsion interactions. It is observed that the maxima of rapidity width,R(η), distribution shifts towards the smaller values ofR(η) with decreasing impact parameter. It is observed that the average pseudorapidity, and the dispersion,D(η) decrease with an increase in the value of different multiplicities of secondary particles. It is also found that andD(η) strongly depend on the impact parameter. The results also reveal that the values of andD(η) remain almost the same beyond grey particle multiplicity, Ng > 11 and heavy ionizing particles, Nh > 28.

Features of relativistic charged particles produced in catastrophic destruction of heavy emulsion nuclei at 4.5 A GeV

Total disintegration events produced in 4.5 A GeV/c 12C--AgBr reactions are analysed to investigate the characteristics of secondary charged particles produced in such collisions. The results reveal that multiplicity distributions of grey, black, and relativistic charged particles agree with the Poisson distribution. The average multiplicity of grey particles is found to increase with the increasing mass of projectile, while the average value of black particles is found to decrease with the increasing mass of projectile. This result is in good agreement with the prediction of fireball model. Finally, the linear dependence of grey and compound multiplicities on black, heavy, and relativistic charged particles is also observed. PACS No.: 25.70

Central collisions of 28Si with Ag(Br) nuclei

Abstract This paper presents data on multiplicity and pseudorapidity distributions of hadrons from central collisions of 28Si with Ag(Br) targets at 4.5 GeV c per nucleon. These events exhibit approximate pseudorapidity distribution scaling in their target as well as in the projectile rest frames. The average pseudorapidity 〈gh〉 is examined as a function of grey particle multiplicity, ng and the effect of intranuclear collisions is discussed. A rough estimation of the energy density has been made from the data of this experiment. Also, a comparison with data from collisions induced by lighter nuclei at the same momentum per nucleon is presented in order to trace the dependence on the projectile mass.

Dependence of the Rapidity Gap Correlations on the Multiplicity of Grey Particles

The characteristics of short-short and short-long rapidity gap correlations in 50 GeV π - -nucleus and 400 GeV proton-nucleus interactions have been investigated. The dependence of the characteristics of clusters on the multiplicity of grey particles, N g , has also been studied. The results reveal that the behaviour of the rapidity gap correlations and the average cluster size are not only independent of the size of the target nucleus but also do not depend on the identity and energy of the impinging hadron. However, the increasing value of the parameter R with increasing value of N g and the energy of the projectile indicates the dominance of the short-short rapidity gap correlations over the short-long correlations.

Determination of cluster size in particle-nucleus interactions at 50 and 400 Gev

We have investigated the formation of clusters and their sizes in 50-GeV ${\ensuremath{\pi}}^{\ensuremath{-}}$-nucleus and 400-GeV proton-nucleus interactions. The maximum multiplicity of charged shower particles constituting the clusters at the two incident energies is observed to be four. Furthermore, the cluster size has been found to be independent of the grey-particle multiplicity and hence the target mass. The cluster size has also been observed to be independent of the energy and identity of the impinging hadrons.

A study of inelastic hadron–nucleus interactions at 50 and 400 GeV

Some results on multiplicity, mean normalized multiplicity, and pseudorapidity distributions of shower particles produced in pion–nucleus and proton–nucleus collisions at 50 and 400 GeV are presented and discussed. From the study of the pseudorapidity distributions, it is found that the projectile fragmentation is mass independent and the target fragmentation depends upon the target size. The effect of nuclear mass on the forward–backward asymmetry is also examined by using the grey particle multiplicity data. Upon using the additive quark model, a new kind of nuclear scaling is observed between RA4, in terms of created charged particles and [Formula: see text].

Leading particle and nuclear-mass effects on multiparticle production in 50 GeV/c π− interactions in nuclear emulsion

An experimental study is carried out on the effects of nuclear mass on leading particle multiplicity and multiparticle production with the help of an emulsion stack exposed to 50 GeV/c π− beam under a strong pulsed magnetic field. The study of the effect of nuclear mass on the forward–backward asymmetry in a π−–A collision is also carried out using the grey particle multiplicity data. The results support the concept of "formation length" of radiation. An attempt is made to explain the space–time structure of hadronic matter in terms of the additive quark model of multiparticle production.