Hadron-nucleus Interactions Research Articles

Scaling of the multiplicity in hadron-nucleus interactions.

It is shown that in interactions of protons at 200, 300, and 400 GeV, and negative pions at 300 GeV with emulsion nuclei, the scaling of the multiplicity of relativistic charged secondaries is valid and described by a linear function of the scaling variable, [ital z].

INTERMITTENCY IN HADRON-NUCLEUS INTERACTIONS AT 200 GeV/c IN TERMS OF FACTORIAL CORRELATORS

Factorial Correlators (FCs), a tool for the test of “intermittency” in multiparticle production in high energy physics, has not been given much attention, compared to the efforts towards understanding the phenomenon in terms of scaled factorial moments. So far, only hadron-hadron data of NA22 collaboration and nucleus-nucleus data of EMU01 collaboration have been analyzed in terms of FCs. However, the present situation of intermittency study demands thorough exploitation of all the available tools for better understanding of the phenomenon. In this article we present the analysis of particle production data of hadron-nucleus interaction at 200 GeV/c in terms of FCs. The results of the analysis show a consistency with the prediction of α-model for the existence of “intermittency.”

Leading hadron inclusive spectra in hadron-nucleus interactions

A description ofhA→hX processes at fixed transverse momenta of detected hadrons is given following the model with intermediate leading states. A good agreement with FNAL experimental data on invariant cross sections of the processes at 0.3≤pτ≲7 GeV/c is obtained.

Clustering phenomena in high energy hadron–nucleus interactions

A hypothetical model based on the production of two clusters in hadronnucleus collisions is proposed. The identification of the produced clusters depends mainly on the analysis of the experimental data in the rapidity space. The predicted angular distribution is compared with experimental data in the energy range 50 to 200 GeV for proton reactions with Cu, Pb and emulsion nuclei as targets. The cluster parameters (mass, momentum, velocity and the particle multiplicity) are studied as a function of the number of target nucleons v encountered by the projectile.

Evidence of Different Pion Coherence Zone in High Energy Hadron-Nucleus and Nucleus-Nucleus Interactions

This paper reports detailed observation of coherent production of pions in hadron-nucleus interactions at 200 to 400 GeV/c and nucleus-nucleus interactions at 2.1 to 4.5 GeV/c per nucleon. The analysis is based on a comparative study of experimental multiplicity distribution in different pseudorapidity bins with Poissonian and Chaotic distributions

Evidence of Different Pion Coherence Zone in High Energy Hadron-Nucleus and Nucleus-Nucleus Interactions

This paper reports detailed observation of coherent production of pions in hadron-nucleus interactions at 200 to 400 GeV/c and nucleus-nucleus interactions at 2.1 to 4.5 GeV/c per nucleon. The analysis is based on a comparative study of experimental multiplicity distribution in different pseudorapidity bins with Poissonian and Chaotic distributions.

Production of slow singly charged fragments in 200 GeV/c hadron nucleus interactions

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.

Charm production in hadronic collisions

We discuss a two-component model of open charm production including high momentum transfer parton fusion and an intrinsic charm component of the projectile. Our model has been applied to charm production in hadron-hadron and hadron-nucleus interactions. We also discuss applications to RHIC physics.

Who killed the J/ ψ?

We discuss some of the ‘hadronic’ effects that play a role in J/ ψ production in hadron-nucleus interactions and that may be important in high energy nucleus-nucleus collisions.

Cross sections and multiplicities in hadron-nucleus collisions with interacting color strings

The energy and [ital A] dependence of the cross sections, number of wounded nucleons, and multiplicities in hadron-nucleus interactions at high energies are discussed in the framework of a probabilistic string model. All observables are calculated analytically. The results show that at present energies observable effects due to string fusion are small. However at higher energies, such as at the CERN Large Hadron Collider or the Superconducting Super Collider, these effects give rise to a spectacular reduction of the multiplicity, which becomes independent of [ital A]. The total cross section, on the contrary, remains proportional to [ital A][sup 2/3] and only its small reduction is predicted.

Self-similarity in particle production in hadron-nucleus interactions at 350 and 200 GeV/c.

Self-similarity in multiparticle production in ${\ensuremath{\pi}}^{\ensuremath{-}}$-nucleus interactions at 350 and at 200 GeV/c has been studied in terms of factorial moments ${F}_{q}$ as well as fractal moments ${G}_{q}$. Fractal parameters, already developed in the classical chaotic system, have been discussed and those parameters for multiparticle production in ${\ensuremath{\pi}}^{\ensuremath{-}}$-nucleus interactions have been evaluated. While the $F$-moment analysis confirms nonstatistical fluctuations, and in terms of anomalous dimensions, predicts cascading in hadronization, multifractality is indicated through the $G$-moment analysis. Variation in the nature or values of fractal parameters have been studied in different sizes of phase space and in different energies for the same reactants. Such a phenomenological analysis is essential at the present stage of development in the study of fractality in multiparticle production.

Dual Parton Model with complete formation zone intranuclear cascade and a minijet component for the description of particle production in heavy ion collisions at collider energies

We present a Monte Carlo version of the Dual Parton Model for the description of particle production in hadron-nucleus and nucleus-nucleus collisions with a complete formation zone intranuclear cascade. Each nucleon nucleon collision is described by the two component Dual Parton Model. Soft hadronic collisions and hard perturbative collisions (minijets) are the two components included in the unitarization scheme. Depending on the transverse momentum cut off we find up to several thousand minijets in collisions of heavy ions at the TeV energies of the future LHC collider. The model is compared with rapidity distributions and grey-particle production in hadron-nucleus interactions as well as with results from nucleus-nucleus collisions. We present predictions for the rapidity and transverse momentum distributions as well as for the hadronic energy density at LHC energies. We also study the cascade of the partons from the perturbative component.

Multiparticle clustering in high-energy interaction. A direct search

This paper presents an analysis on the direct search of multiparticle clusters produced in hadron-nucleus interactions using the method of Lepekhin and Simonov. It is observed that clusters of three, four and five particles are present in the multiple production in π--AgBr interaction at 350 GeV/c, whereas the conventional methods do not reveal any higher-order clustering.

Dual parton model with complete formation zone intranuclear cascade for the description of particle production in hadron-nucleus and nucleus-nucleus interactions

We present a Monte Carlo version of the dual parton model for the description of particle production in hadron-nucleus and nucleus-nucleus collisions with a complete formation zone intranuclear cascade. All generations of secondary interactions are considered. Furthermore, Fermi motion and Pauli's principle are introduced to control the generation of low-energy nucleons. The model is compared with rapidity distributions and grey-particle production in hadron-nucleus interactions as well as with results from nucleus-nucleus collisions. Within the DPM the number of chains with sea-quarks at their ends grows with the complexity of the target and/or projectile nuclei as well as with the collision energy. We discuss this increase of chain-end sea-quarks as a mechanism for strangeness enhancement within the model. Furthermore we study the properties of the model at the energies of future heavy ion colliders.

HARD HADRON-NUCLEUS PROCESSES IN THE DYNAMICAL RESCALING MODEL

We develop the dynamical rescaling model in the case of hard hadron-nucleus processes at high energy. It is shown that the rescaling effect takes place both for hadron which penetrates through the nuclear medium and for the bound nucleon. The main reason for the rescaling is the quasielastic re-scattering of quarks from the incoming hadron on the nucleons inside the nucleus before the hard subprocess. We demonstrate a very good agreement data of J/Ψ and leptonic pairs xF-spectra in hadron-nucleus interaction with our results.

Negative binomial distribution for hadron-nucleus interactions

Assuming the validity of the negative binomial distribution for hadron-nucleus interactions, the Singh-Uddin-Kamal relation between the two parameters k A and n ̄ s of the distribution is derived and is found to be universally valid for proton-proton as well as proton-nucleus interactions at high energy. We further deduce the target-mass number dependence and the energy dependence of the parameter k A .

Tests of punch-through simulations

Simulations of the punch-through in hadronic showers will be presented. This includes a detailed analysis of the beam fragmentation in hadron-nucleus interactions. The results shown have been obtained with the GHEISHA and GEANT Monte Carlo programs. Comparisons with experimental data in the range of 2–300 GeV beam energy will be performed. The use of a fast Monte Carlo version, based on simplifications of the general GHEISHA shower simulation program, will be described and the limits of applicability will be investigated. Alternative solutions of punch-through calculations by use of the Boltzmann transport equation will be demonstrated. Muon identification in past and future collider experiments is reviewed and the performance will be compared with predictions of Monte Carlo calculations.

Characteristics of hadron-nucleus interactions with and without emission of hadrons in the backward hemisphere

An attempt has been made to study the emission of hadrons produced in the backward hemisphere in nuclear emulsion at 340 GeV pion-nucleus and 400 GeV proton-nucleus collisions. Some characteristics of grey particles emitted in the forward and backward hemispheres have been investigated. The dispersion of relativistic particles depends linearly on the average multiplicity. The observed difference between the behaviour of angular distribution of grey (shower) particles in hadron-nucleus interactions with and without the emission of shower (grey) particles has also been discussed.

Nuclear response and hadron formation length in high-energy hadron-nucleus interactions.

A simple Monte Carlo cascade model which gives the exclusive description of the hadron-nucleus collisions is described. Comparison with the data on pAr, pXe collisions at 200 GeV suggests that at this energy all secondary particles are produced basically by the multiple collisions of a projectile and by the cascading of the recoiled nucleons inside the nucleus, while the cascading of the secondary pions is rather negligible.

Topological cross-section in hadron-nucleus collisions and multiple scattering theory

The multiple scattering theory supplemented with AGK cutting rules is applied to calculation of the hadron-nucleus interaction cross-sections. In contrast to standard Glauber approach neither smallness of the interaction radius compared to the nuclear radii nor Gaussian form of thehN-interaction profile function are assumed. We consistently use the theory of the supercritical Pomeron. However all the results are more general and do not depend on the specific parametrization of the Pomeron pole ampletude. The region of validity of the widely used approximate formulae for topological and totalhA-interaction cross sections are discussed. It is discussed the novel features of particle-nucleus interactions at superhigh energies.