AgBr Nuclei Research Articles

System size dependence in backward relativistic hadron production in pA and AA collisions

In this comprehensive study the multiplicity characteristics of the backward emitted relativistic hadron (shower particle) through hadron-nucleus and nucleus-nucleus are overviewed in three dimensions. These dimensions are the projectile size, target size, and energy. To confirm the universality in this production system, wide ranges of system size and energy (Elab ∼ 2.1 A up to 200 A GeV) are used. The multiplicity characteristics of this hadron imply a limiting behavior with respect to the projectile size and energy. The target size is the main effective parameter in this production system. The exponential decay shapes is a characteristic feature of the backward shower particle multiplicity distributions. The decay constant changes with the target size to be nearly 2.02, 1.41, and 1.12 for the interactions with CNO, Em, and AgBr nuclei, respectively, irrespective of the projectile size and energy. While the backward production probability and average multiplicity are constants at different projectile sizes and energies, they can be correlated with the target size in power law relations.

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

Determination of The Reaction Plane and Collective Flow In Nucleus-Nucleus Interactions at 4.5 A GeV/c

Nuclear emulsions are used to investigate spallations produced by 4.5 A GeV/c 24 Mg and 28 Si nuclei. The integral multiplicity distribution of disintegrated particles from target nuclei is used to separate the inelastic interactions with the free hydrogen (H), the light (CNO), and the heavy (AgBr) nuclei. Angle of flow, transverse momentum, angular characteristics, and azimuthal alignment data are analyzed for the presence collective fragments in 24 Mg+ Ag( Br) and 28 Si+ Ag( Br) collisions with emulsion nuclei at 4.5 A GeV/c. The determination of the reaction plane is powerful tool for investigating the nucleus-nucleus interactions. The analysis of the projection of the transverse momentum, angular characteristics, azimuthal alignment and range onto the reaction plane shows a significant side splash of the target fragment.

Characteristics of the total disintegration of AgBr nuclei by <sup>24</sup>Mg and <sup>32</sup>S nuclei at 4.5 A GeV/<i>c</i>

Characteristics of the total disintegration of AgBr nuclei by <sup>24</sup>Mg and <sup>32</sup>S nuclei at 4.5 A GeV/<i>c</i>

Bounce – off in 197Au induced collisions with Ag(Br) nuclei at 11.6 A GeV/c

Using emulsion detectors a transverse-momentum analysis of projectile fragments has been performed in Au induced nuclear interactions at 11.6 A GeV/c. Evidence for collective flow of the projectile fragments has been obtained. Angular distributions of the principal vectors of projectile and target fragments have shown strong azimuthal correlation.

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.

One- and two-dimensional multifractals in proton-AgBr interactions at 800 GeV.

We analyze the multifractal structure in one and two dimensions of multihadronic final states produced in proton interactions with AgBr nuclei at 800 GeV in terms of modified G moments. Explicit corrections have been made for the finite statistical sample. The generalized dimensions ${\mathit{D}}_{\mathit{q}}$ have been determined for q=1--5. The observed multifractal structure of multiparticle production is well represented by the p model of self-similar cascading. The phenomenological parameter p drops in value in going from two to one dimensions, and shows weaker dependence on multiplicity for high multiplicity events compared to low multiplicity events. \textcopyright{} 1996 The American Physical Society.

INTERACTIONS OF RELATIVISTIC 24Mg NUCLEI WITH EMULSION NUCLEI AT 4.5 GeV/c PER NUCLEON

Nuclear emulsions are used to investigate spallations produced by 108 GeV/c 24Mg nuclei. The main experimental characteristics (inelastic cross-sections and multiplicities of various types of secondary particles and their dependence on the masses of the colliding nuclei) in inelastic interactions of 24Mg nuclei with nuclei of nuclear emulsion at 4.5 GeV/c per nucleon have been studied. The integral multiplicity distribution of disintegrated particles from target nuclei is used to separate the inelastic interactions with the free hydrogen (H), the light (CNO), and the heavy (AgBr) nuclei. Multiplicity scaling in the shower particles obeys a scaling function of Koba-Neilsen-Olesen (KNO) type in this energy region.

Observation of Strong Multiproton Correlationin Proton-Nucleus Interaction at 400 GeV/c

Three-proton correlations in 400 GeV/c with AgBr nuclei have been studied in this paper in the Monte-Carlo background and search for short range dynamical correlations has been made. It is interesting to observe that strong correlations exist in both backward and forward hemisphere in p-AgBr emulsion where in case of π-AgBr interaction at 350 GeV/c correlations exist only in backward hemisphere and there is the evidence of strong correlation.

EVIDENCE OF INTRA- AND INTERGROUP AZIMUTHAL CORRELATIONS IN NUCLEAR INTERACTIONS AT A FEW GeV/c

The paper presents new data on azimuthal correlations in angles between different types of secondary charged particles emitted in inelastic interactions between 24Mg nuclei with the AgBr nuclei of nuclear emulsion. Azimuthal correlations are observed in some cases of intergroup correlations, and an asymmetry is found to exist in the emission of the same type of particles. The present data is compared in some cases, with those of p-emulsion, d-emulsion, α-emulsion and 12C-emulsion interactions at 4.5 A GeV/c and 84Kr-emulsion interaction at 1.4 A GeV.

Factorial moments in high-multiplicity events in 800 GeV proton interactions with AgBr nuclei

The scaled factorial moments were investigated for secondary particles in high-multiplicity events produced by 800 GeV proton interactions with AgBr nuclei in a nuclear emulsion. The results show clear evidence for power-law behavior of scaled factorial moments. The variation of dimension as a function of order of the moment was also studied. The presence of phase transitions is not indicated from our data. From the behavior of the third-differential moment, we do not find any evidence for the clustering of particles in any pseudorapidity region.

Self-similarity in one and two dimension of 800 GeV proton interactions with AgBr nuclei

The normalized multiplicity moments in one and two dimensions were investigated for secondary particles produced in 800 GeV proton interactions with AgBr nuclei in nuclear emulsion. The fluctuations are found to be more in two dimensions as compared to one dimension. It has been shown that the self-similar cascade model describes well the observed fluctuations. The multiplicity shows a weaker dependence of moments for high multiplicity events in comparison to all multiplicity events. The slope ratios (rq) are not different in one and two dimensions and are found to be independent of the multiplicity. Therq distribution is well represented by the logbinomial and Levy-stable distributions which follows from the self-similar cascade model.

Multiplicities of secondaries in interactions of 1.8 GeV/nucleon 56Fe nuclei with photoemulsion and the cascade evaporation model

A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of 56Fe nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases.

Complete disintegration of heavy nuclei induced by 340 GeV negative pions

The total disintegration of AgBr nuclei caused by 340 GeV negative pions is investigated. The probability of this phenomena depends on the energy of the pion projectile. The angular distributions of grey and black tracks are investigated. Results for the rapidity gap correlation in these catastrophic destructions are also presented.

Nucleation behavior in the precipitation of a sparingly soluble salt - AgBr

Nucleation behavior during the early stages of the precipitation of a sparingly soluble salt (AgBr) was studied experimentally. Direct electron microscopy and light-scattering photometry were used to determine the average diameter and the number of the AgBr nuclei. For a given reactant addition rate R, the number of AgBr nuclei increased at first, reached a maximum, and then started to decrease. The slope of the ln-ln plot of the maximum number versus R was ∾ 1.5, indicating a bulk-diffusion growth mechanism for the AgBr nuclei. The average diameter of the nuclei was 0.008–0.015 μm, and changed with precipitation time. The supersaturation ratio S, calculated from the average nuclei diameter and the Gibbs-Thomson equation, showed the same behavior as that from a theoretical prediction. However, the calculated S values were significantly smaller than a critical value reported for the homogeneous nucleation of AgBr nuclei. These smaller S values can be explained qualitatively by a nuclei survival concept.

Cascade model analysis of the interactions of 17.2 GeV mesons with heavy emulsion nuclei

The comparison of the theoretical results obtained in ref. [1] on the basis of internuclear cascade initiated in AgBr nuclei by 17 GeV mesons with our experimental results shows that the theoretical results are in good agreement only with events having N h ⩾ 8 but not with an overall sample of AgBr events.

Nuclear Surface Effects in Muon Capture

Slow-muon capture in heavy nuclei results in a moderately excited nucleus which emits mostly neutrons and to a lesser extent, charged particles. The neutron and alpha emissions can be explained as statistical emission from the compound nucleus formed. The experimentally observed proton emission is ten times higher than that predicted by the same mechanism. It is proposed to take into account clustering of nucleons at the nuclear surface in order to account for the increased proton emission. The capture of the muon by two-nucleon clusters at the surface of AgBr nuclei is calculated and the subsequent direct proton emission evaluated. The experimental findings can be explained with a reasonable strength of correlations assumed.