Study of compound particle production in 84Kr-emulsion interactions at 1.7 A GeV

The characteristics of compound particle multiplicity distribution and multiplicity correlations between the compound particle and the grey particle, black particle, shower particle and heavily ionized track particle are investigated in this paper. It is found that the average multiplicities of the grey particle, black particle, shower particle and heavily ionized track particle increase with an increase in the number of compound particles, which can be explained by the impact geometrical model. The compound multiplicity distribution is observed to obey a Koba-Nielson-Olesen (KNO) type of scaling law.     

Projectile spectator proton production in 84Kr-emulsion interactions at 1.7 A GeV

The multiplicity distribution of projectile protons and multiplicity correlations between black particles, grey particles, shower particles, compound particles, heavily ionized track particles, projectile helium fragments and projectile spectator protons in <'84>Kr-emulsion collisions at 1.7 A GeV are investigated. It is found that the projectile spectator proton multiplicity distribution becomes broader with increasing target mass. The average multiplicity of shower particles and compound particles strongly depends on the number of projectile spectator protons, but the average multiplicity of black particles, grey particles and heavily ionized track particles weakly depends on the number of projectile spectator protons. The average multiplicity of projectile helium fragments increases linearly with increasing numbers of projectile spectator protons. Finally, the multiplicity distribution of projectile spectator protons obeys a KNO type of scaling law.     

Multiplicity distributions of shower particles and target fragments in 7Li–Em collisions at 3 A GeV/c

Multiplicity distributions of shower particles and target fragments in ⁷Li–Em (emulsion) collisions at 3 A GeV/c are experimentally studied. In the framework of the multisource thermal model, the multicomponent Erlang distribution is used to describe the experimental multiplicity distributions of shower particles, grey fragments, black fragments, and heavily ionized fragments. The correlations between these multiplicities are experimentally reported. With the increase of impacting centrality (or the target fragment multiplicity), a saturation phenomenon for shower particle multiplicity is observed in the experiment.     

Investigation of Multiplicity of Alpha-particle Interactions with Emulsion at 12A GeV

The multiplicity distribution of charged secondary particles and correlation between shower particles and heavy particles of alpha-particle interaction with nuclear emulsion at 12A GeV are discussed.The results indicate the mean multiplicity of heavy particle increase with shower particle numbers.     

Study of compound particle production in ~（84）Kr-emulsion interactions at 1.7 A GeV

The characteristics of compound particle multiplicity distribution and multiplicity correlations between the compound particle and the grey particle, black particle, shower particle and heavily ionized track particle are investigated in this paper. It is found that the average multiplicities of the grey particle, black particle, shower particle and heavily ionized track particle increase with an increase in the number of compound particles, which can be explained by the impact geometrical model. The compound multiplicity distribution is observed to obey a Koba-Nielson-Olesen (KNO) type of scaling law.     

Systematic study of multiparticle production in nucleus–nucleus interactions at 14.6 A GeV

An experimental analysis of 855 events induced by 14.6 A GeV ²⁸Si in nuclear emulsion is presented. Mean multiplicities of charged secondary particles produced in the nuclear interactions are studied and compared with the results from the other experiments for the same projectile at 3.7 A GeV as well as data for proton at similar energy (14 GeV). An analysis of pseudorapidity densities of target fragments (black and grey particles) is also performed. The behaviour of the KNO scaling law of the multiplicity distribution for shower particles has been examined. In order to accumulate knowledge about the intermittent behaviour of shower particles, the scaled factorial moments (SFMs) are computed in η-space and ?-space for a set of data in the ²⁸Si–AgBr events. Furthermore, validity of limiting fragmentation of shower particles produced in central collision events induced by ²⁸Si-emulsion interactions has been tested. A crude estimation for the energy density of the nuclear matter formed in the central collision events at our energy has been examined.     

A study of 12C and 28Si interactions with heavy emulsion targets

This paper presents some general characteristics of totally disintegrated events observed in the interactions of Silicon and Carbon with Ag/Br nuclei. The events with heavy particle multiplicity greater than or equal to twenty-eight, i. e., N_h ≥ 28 were analyzed. The probability of occurrence of central collision events is found to increase with the mass of the projectile and total projectile energy. The multiplicity distributions are described quite well by a Gaussian curve. The variation in the mean multiplicity of grey, black, heavy, and shower particles with projectile mass is being discussed. Average compound particle multiplicity is found to increase with the mass of the projectile.     

Projectile spectator proton production in 84Kr- emulsion interactions at 1.7 A GeV

The multiplicity distribution of projectile protons and multiplicity correlations between black particles, grey particles, shower particles, compound particles, heavily ionized track particles, projectile helium fragments and projectile spectator protons in ⁸⁴Kr-emulsion collisions at 1.7 A GeV are investigated. It is found that the projectile spectator proton multiplicity distribution becomes broader with increasing target mass. The average multiplicity of shower particles and compound particles strongly depends on the number of projectile spectator protons, but the average multiplicity of black particles, grey particles and heavily ionized track particles weakly depends on the number of projectile spectator protons. The average multiplicity of projectile helium fragments increases linearly with increasing numbers of projectile spectator protons. Finally, the multiplicity distribution of projectile spectator protons obeys a KNO type of scaling law.     

Analysis of multiparticle production data on proton-nucleus collisions using a new variable

Multiparticle production data on proton-nucleus collisions have been analyzed taking the number of ‘created’ charged particles instead of the observed number of shower particles as the variable. The mean normalized multiplicity,R _A , has been found to be independent of energy in the energy range (7–8000) GeV and its mass number dependence has been obtained. The modified analysis introduces some more regularities in the experimental results onp-nucleus collisions like the invariance with respect to energy of the relationshipR _A = α + βN _h and the KNO-like scaling of the multiplicity distributions of the created charged particles. The functional form of the scaling function has been calculated.     

On the origin of approximate KNO scaling ine + e − annihilation

KNO scaling of the multiplicity distribution in hadronic final states was originally derived as a consequence of Feynman scaling. We show that in iterative models of hadron production in jets, incorporating Feynman scaling, KNO scaling obtains only in the limit when the width of the multiplicity distribution tends to zero. Within the context of the models currently employed to describee ⁺ e ^? annihilation into hadrons, the apparent KNO scaling observed is an accidental consequence of effects which violate Feynman scaling.     

A comment on the early onset of semi-inclusive scaling in proton-proton collisions

The present experimental evidence for the scaling of multiplicity distributions predicted by Koba, Nielsen and Olesen is examined critically. Our results indicate that the approximate scaling observed experimentally is not necessarily connected with an “early” approach to the asymptotic limit. Some simple models are shown to predict an extremely slow approach to scaling. The possibility of distinguishing between “early” scaling ang the “quasi-scaling” exhibited by these models with experiments at ISR is discussed.     

Multiplicity distribution in proton-proton and proton-antiproton collisions at high energies

Multiplicity distributions of secondary hadrons produced in p $ \bar p $ \bar p and collisions are very different. There are three types of inelastic processes in p $ \bar p $ \bar p scattering. The first one is the production of a shower of secondary hadrons in gluon string decay. The second one is the shower produced from the decay of two quark strings, and the third one is the shower produced from the decay of three quark strings. At the same time, there are just two types of inelastic processes for pp scattering: the shower from the gluon string and the shower from two quark strings. The multiplicity distribution and the average multiplicity of charged hadrons for an energy of 14 TeV are predicted.     

Multiplicity characteristics in relativistic 24Mg-nucleus collisions

This work is concerned with the analyses of the shower and gray particle production in 4.5 A GeV/c ²⁴Mg collision with emulsion nuclei. The highest particle production occurs in the region of the low impact parameters. While the multiplicity of the shower particles emitted in the forward direction depends on the projectile mass number and energy, the multiplicity of the backward ones shows a limiting behaviour. The source of the emission of the forward shower particles is completely different from that of the backward ones. The target fragments are produced in a thermalized system of emission.     

Multiplicities of forward-backward particles in16O-emulsion interactions at 4.5 AGeV/c

An exclusive study of the characteristics of interactions accompanied by backward emission (θlab≥ 90°) of shower and grey particles in collisions of a 4.5 AGeV/c 16O beam with emulsion nuclei is carried out. The experimental multiplicity distributions of different particles emitted in the forward (θlab<90°) and backward hemispheres due to the interactions with the two emulsion components (CNO, AgBr) are presented and analyzed. The correlations between the different emitted particles are also investigated. The results indicate that there are signatures for a collective mechanism, which plays a role in the production of particles in the backward hemisphere. Hence, the backward multiplicity distribution of the emitted shower and grey particles at 4.5 AGeV/c incident momentum can be represented by a decay exponential law formula independent of the projectile size. The exponent of the power was found to increase with decreasing target size. The experimental data favor the idea that the backward particles were emitted due to the decay of the system in the latter stages of the reactions.     

Multiplicities in electroproduction and e+e− annihilation

It is shown how more sophisticated versions of the parton model can replace the naive expectation of final state hadrons being produced in ep or e⁺e^? collisions in two jets of finite multiplicity, well-separated in rapidity, with a picture that permits the rapidity gap to be filled in and allows the multiplicity to rise with energy, even up to the limit imposed by energy conservation. Large multiplicity is shown to imply a rather slow approach to scaling and a significant tail in the transverse momentum distribution.     

290 AMeV 12C诱发乳胶核反应末态粒子多重数关联

对290 AMeV 12C诱发乳胶核反应末态粒子间的多重数关联进行了研究。实验结果表明:黑径迹粒子、灰径迹粒子、重电离粒子多重数之间存在较强的关联,而且黑径迹粒子和重电离粒子多重数有饱和的趋势,这些特征与高能区实验结果一致;簇射粒子与其他粒子间的关联性较弱,这一特征与高能区实验结果不同,主要归因于弹核能量较低、簇射粒子产额较小;黑径迹粒子、灰径迹粒子在前后半球的平均多重数随靶核的增大而增加;实验结果可用基于碰撞几何的旁观体-反应体模型及级联蒸发模型来解释。We have investigated the multiplicity correlation of particles produced in 12C-emulsion interactions at 290 AMeV. It is found that there is a strong correlation between black track particle, grey track particle and heavily ionized track particle, and finally black track particles and heavily ionized track particles tend to saturation, which is the same as the experimental results observed at high energies. The multiplicity correlation between shower particle and other particles is weaker, which is different from the experimental results observed at high energies. This discriminating character can be explained by the lower energy of projectile. The productivity of shower particle is lower at intermediate energies compared to that at high energies. The forward-backward averaged multiplicity of black track particle and grey track particle increases with the increasing target size.     

A study of charged particle multiplicities in hadronic decays of theZ0

We present an analysis of multiplicity distributions of charged particles produced inZ ⁰ hadronic decays. The results are based on the analysis of 82941 events collected within 100 MeV of theZ ⁰ peak energy with the OPAL detector at LEP. The charged particle multiplicity distribution, corrected for initial-state radiation and for detector acceptance and resolution, was found to have a mean n _ch=21.40±0.02(stat.)±0.43(syst.) and a dispersionD=6.49±0.02(stat.)±0.20(syst.). The shape is well described by the Lognormal and Gamma distributions. A negative binomial parameterisation was found to describe the shape of the multiplicity distribution less well. A comparison with results obtained at lower energies confirms the validity of KNO(-G) scaling up to LEP energies. A separate analysis of events with low sphericity, typically associated with two-jet final states, shows the presence of features expected for models based on a stochastic production mechanism for particles. In all cases, the features observed in the data are well described by the Lund parton shower model JETSET.deceased 25th March 1991     

4.5AGeV/c 24Mg与核乳胶碰撞中簇射粒子的赝快度分布

报道了4.5AGeV/c ²⁴Mg与核乳胶碰撞中产生的簇射粒子的赝快度分布,结果表明,分布宽度和峰值位置明显依赖于靶核尺寸.用柱模型对赝快度分布进行了分析,MonteCarlo方法计算得到的结果基本符合实验数据的走向,并重现了实验数据中的涨落现象.     

Characteristics of alpha projectile fragments emission in interaction of nuclei with emulsion

The properties of the relativistic alpha fragments produced in interactions of ⁸⁴Kr at around 1 A GeV in nuclear emulsion are investigated. The experimental results are compared with the similar results obtained from various projectiles with emulsion interactions at different energies. The total, partial nuclear cross-sections and production rates of alpha fragmentation channels in relativistic nucleus-nucleus collisions and their dependence on the mass number and initial energy of the incident projectile nucleus are investigated. The yields of multiple alpha fragments emitted from the interactions of projectile nuclei with the nuclei of light, medium and heavy target groups of emulsion-detector are discussed and they indicate that the projectile-breakup mechanism seems to be free from the target mass number. It is found that the multiplicity distributions of alpha fragments are well described by the Koba-Nielsen-Olesen (KNO) scaling presentation. The mean multiplicities of the freshly produced or newly created charged secondary particles, normally known as shower and secondary particles associated with target in the events where the emission of alpha fragments were accompanied by heavy projectile fragments having Z ≥ 3 seem to be constant as the alpha fragments multiplicity increases, and exhibit a behavior independent of the alpha fragments multiplicity.     

Pseudorapidity Distribution of Shower Particles in 24Mg-Emulsion Collisions at 4.5A GeV/c

The pseudorapidity distribution of shower particles produced in the ²⁴Mg-emulsion collisions at 4.5A GeV/c is reported in this paper. The dependences of the distribution width and the peak position on the target size are observed.The pseudorapidity distribution of shower particles for the events with low target multiplicity (light target) is narrower than that with high target multiplicity (heavy target). The maximum probability pseudorapidity for light target is greater than that for heavy target. The experimental data is analyzed by using the cylinder model suggested by Liu et al. The Monte Carlo results based on Liu's cylinder model are approximately in agreement with the experimental tendency and fluctuation.