Intermittency in the Slow Particle Emission During HadronNucleus Interactions (original) (raw)
Dynamics of hadron nucleus interactions
Nuclear Physics A, 1982
Recent progress in diffraction theory shows that proton-nucleus scattering at nonforward angles is dominated by the interference of waves from two or more "bright spots". Analytic formulas based on asymptotic theories of diffraction yield valuable new insights into the scattering and these formulas can be readily extended to illuminate the role of dynamical ingredients, i.e., the nucleon-nucleon amplitudes. The governing parameters of the diffraction and some direct connections between the observed cross sections and the inp-. t dynamics are reviewed. New information regarding the nucleon-nucleon parameters based on recent phase shift analyses show some systematic differences from the "effective" NN amplitudes which produce fits to proton-nucleus diffraction data. Recent progress in understanding the role of ^.-isobars in proton-nucleus dynamics is reviewed.
Slow Particle Production in Nucleus-Nucleus Collisions at Relativistic Energies
Journal of Modern Physics, 2016
In this paper an effort has been made to study the general characteristics of slow particles produced in the interactions of 32 S-Em at 200 AGeV to extract the information about the mechanism of particle production. The results have been compared with the experimental results obtained by other workers. The multiplicity distributions of the slow target associated particles (black, grey and heavy tracks) produced by 32 S-beam with different targets have been studied. Also several types of correlations among them have been investigated. The variation of the produced particles with projectile mass number and target size has been studied. Also the multiplicity distributions of slow particles with NBD fits are presented and scaling multiplicity distributions of slow particles produced have been studied in order to check the validity of KNO-scaling.
Extended Statistical Thermal Model and Rapidity Spectra of Hadrons at 200 GeV/A
2009
We use the extended statistical thermal model to describe various hadron rapidity spectra at the highest RHIC energy (200 GeV/A). The model assumes the formation of hot and dense regions moving along the beam axis with increasing rapidities, yFB. It has been earlier shown that this model can explain the net proton flow i.e. p minus pbar, ratio pbar/p and the pion rapidity spectra. In this paper we have attempted to show that in addition to these quantities, this model can also successfully describe the individual rapidity spectra of protons, antiprotons, Kaons, antiKaons, pions, the ratios lambdabar/lambda and cascadebar/cascade. The experimental data set on p, pbar, K, Kbar and Pion provided by BRAHMS collaboration at the highest energy of Relativistic Heavy Ion Collider, sqrt(SNN) = 200 GeV are used. The theoretical results fit quite well with mid-rapidity data (for y < 1) of the lambdabar/lambda and the cascadebar/cascade ratios available (from STAR). We have used single set of model parameters including single value of the temperature parameter T for all the regions of the hot and dense matter formed. The chemical potentials are however assumed to be dependent on the fireball rapidity yFB. We have analyzed the contribution of the decay of the heavier resonances to the proton (antiproton) rapidity spectra. It is found that the rapidity spectrum of the product hadron is nearly same as that of the parent hadron. We have also imposed the criteria of exact strangeness conservation in every (local) region of the dense matter separately, which is necessary. We also discuss what can be learned about the nuclear transparency effect at the highest RHIC energy from the net proton rapidity distribution.
Production of slow singly charged fragments in 200 GeV/c hadron nucleus interactions
Zeitschrift für Physik C Particles and Fields, 1993
Measurements of slow, singly charged fragments in the target rapidity region have been performed for proton and pion induced reactions with various nuclei at 200 GeV/c. Multiplicity, angular and energy distributions are examined and used to study the effects of rescattering in the nuclear medium. Data are compared to a "geometric cascade model" and to simulations with the VENUS 3.11 and the FRITIOF 1.7 Monte Carlo codes.
Intermittency and erraticity of charged particles produced in 28 Si-Ag/Br interaction at 14.5 A GeV
Canadian Journal of Physics, 2011
In this paper, we present the intermittency and the erraticity analyses of the distributions of charged particles produced in Si-Ag/Br interaction at incident energy 14.5 A GeV. The experimental results are compared with a Monte Carlo simulation using ultra-relativistic quantum molecular dynamics (UrQMD) model. The experimental data show the presence of a nonstatistical component in the produced charged-particle density. Neither the UrQMD simulation nor the purely statistical simulation was found to match the experimental data. The present set of results are compared to those obtained in similar measurements from earlier high-energy nucleus-nucleus experiments. PACS Nos: 25.75.-q, 25.70.Mn, 24.60.Ky
Non-Equilibrium Approach to Dense Hadronic Matter
International Journal of Modern Physics E
A general approach to the kinetics of a hadronic many-particle system is formulated employing a nonequilibrium diagram technique. The investigation of medium effects is based on the analysis of the coupled set of nonequilibrium Dyson equations for the π, N, and Δ components. Some model approaches to their solution are considered. The results are applied to the study of expanding hadronic fireballs containing pions, nucleons, and deltas as produced in the course of heavy-ion collisions at energies provided by the GSI-SIS up to the CERN-SpS.
2007
We discuss the experimental results on the behavior of the average multiplicities and angular distributions of slow particles emitted in hadron-nuclear and nuclear-nuclear interactions at relativistic energies as a function of the centrality of collisions. It is observed that by increasing the mass of the projectiles the angular distributions of slow particles change and the structure which was demonstrated in the case of π-mesons, protons and light nuclear projectiles, almost disappears. During the interaction of the heavier projectile with nuclear target, the number of secondary interactions as well as number of nucleon-nucleon elastic scattering and re-scattering events increases. We suggest to restore this information using the heavy ion generators taking into account the multiplicity distributions. Because our investigations show that the formation of the percolation cluster sufficiently influences the behaviour of the average multiplicity of the slow particles emitted in these interactions.
Beam–plasma instability and fast particles: the Lynden-Bell approach
Plasma Physics and Controlled Fusion, 2014
The beam-plasma instability, i.e., the response of the plasma bulk to the injection of supra thermal charged-particle beams, results to be appropriately characterized by a long-range interaction system. This physical system hosts a number of very interesting phenomena and, in particular, the emergence of long-lived quasi-stationary states. We characterize the self-consistent distribution functions of such out-of-equilibrium states by means of the Lynden-Bell's theory. The prediction of this theory, based on the statistical mechanics of the Vlasov equation, are checked against the outcomes of numerical simulations of the discrete system. Moreover, a phenomenological study of the effective resonance band for the system response is also addressed. A threshold value has been found in the initial spread of beam-particle momenta. This threshold allows to discriminate between the resonant and non-resonant regimes. The analysis of the thermalization of a few percents of the beam population characterized by large initial momenta (with respect to the main part of the beam itself) is also performed and it confirms and deepens the understanding of the physical meaning of the mentioned threshold.
Fast nucleon emission: A probe of the heavy ion reactions at energies below 100 MeV/u
Nuclear Physics A, 1984
After a review of the various theoretical models which describe the fast nucleon emission in heavy-ion reactions at bombarding energies lower than 100 MeV/u, the Boltzmann equation is discussed as a tool for studying the reaction mechanisms in this energy range. The Boltzmann equation allows to analyze the balance between one-and two-body processes. A linearized version is derived to study the transport in nuclei of fast nucleon flows generated by the reaction dynamics. Results are presented showing that the high energy tails of the spectras can be interpreted without reference to statistical emissions from hot nuclear fragments. 1. INTRODUCTION Free nucleons are a quasi-permanent output of the heavy-ion collisions ; the least bound nucleons in nuclei have a binding energy of approximately 8 MeV, which is small when compared with the relative kinetic energy of the ions. Even at low energies, nucleon emission is then an open channel for the dissipation of the excitation energy, the linear and angular momenta of the interacting system. At very low bombarding energies (a few MeV per nucleon), it is generally accepted that the nucleon emission occurs statistically from either the emerging fragments or from the compound system (see refs. 1-4). At higher bombarding energies (typically higher than 8 MeV per incident nucleon), there are well established evidences for non-statistical neutron5-8 and proton'-I1 emissions. Due to their non-equilibrated character, these emissions have been thought to bear signatures of the processes from which they originate and, by the way, to provide probes of the reaction dynamics. This work will follow such a philosophy ; it will be specialized in reactions the bombarding energies of which do not exceed 100 MeV per nucleon. This energy range is presently under focus owing to the recent availability of experimental data12 ; it is interesting too from a theoretical point of view, since one expects to observe the transition between a regime where the reactions are mainly governed by the nuclear mean field and a regime where, the binding energies the nucleons becoming progressively negligible, the reactions are dominated the individual collisions.