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Title: Centrality and multiparticle production in ultrarelativistic nuclear collisions

Abstract

A critical analysis of methods for selecting central events in high-energy proton–nucleus (pA) and nucleus–nucleus (AA) collisions is presented. A sample of event classes in which background fluctuations associated with the dispersion of the impact parameter of each event or the number of participant nucleons are minimal is examined. At the SPS and LHC energies, the numbers of nucleon–nucleon collisions are estimated with the aid of the Monte Carlo event generators HIJING and AMPT, which take into account energy–momentum conservation, and on the basis of a non-Glauber model involving string fusion and a modified Glauber model. The results obtained in this way demonstrate the need for revising the extensively used application of the Glauber model in normalizing multiplicity yields in experimental data on pA and AA collisions in the soft region of the spectrum.

Authors:
; ; ;  [1]
  1. Universitetskaya Naberezhnaya 7-9, St. Petersburg State University (Russian Federation)
Publication Date:
OSTI Identifier:
22612616
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 79; Journal Issue: 5; Other Information: Copyright (c) 2016 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ATOM-ATOM COLLISIONS; CERN LHC; EXPERIMENTAL DATA; GLAUBER THEORY; IMPACT PARAMETER; MONTE CARLO METHOD; MULTIPLICITY; PROTON-NUCLEON INTERACTIONS; RELATIVISTIC RANGE; SPECTRA

Citation Formats

Drozhzhova, T. A., Kovalenko, V. N., Seryakov, A. Yu., and Feofilov, G. A., E-mail: grigory-feofilov@yandex.ru. Centrality and multiparticle production in ultrarelativistic nuclear collisions. United States: N. p., 2016. Web. doi:10.1134/S1063778816040074.
Drozhzhova, T. A., Kovalenko, V. N., Seryakov, A. Yu., & Feofilov, G. A., E-mail: grigory-feofilov@yandex.ru. Centrality and multiparticle production in ultrarelativistic nuclear collisions. United States. doi:10.1134/S1063778816040074.
Drozhzhova, T. A., Kovalenko, V. N., Seryakov, A. Yu., and Feofilov, G. A., E-mail: grigory-feofilov@yandex.ru. Thu . "Centrality and multiparticle production in ultrarelativistic nuclear collisions". United States. doi:10.1134/S1063778816040074.
@article{osti_22612616,
title = {Centrality and multiparticle production in ultrarelativistic nuclear collisions},
author = {Drozhzhova, T. A. and Kovalenko, V. N. and Seryakov, A. Yu. and Feofilov, G. A., E-mail: grigory-feofilov@yandex.ru},
abstractNote = {A critical analysis of methods for selecting central events in high-energy proton–nucleus (pA) and nucleus–nucleus (AA) collisions is presented. A sample of event classes in which background fluctuations associated with the dispersion of the impact parameter of each event or the number of participant nucleons are minimal is examined. At the SPS and LHC energies, the numbers of nucleon–nucleon collisions are estimated with the aid of the Monte Carlo event generators HIJING and AMPT, which take into account energy–momentum conservation, and on the basis of a non-Glauber model involving string fusion and a modified Glauber model. The results obtained in this way demonstrate the need for revising the extensively used application of the Glauber model in normalizing multiplicity yields in experimental data on pA and AA collisions in the soft region of the spectrum.},
doi = {10.1134/S1063778816040074},
journal = {Physics of Atomic Nuclei},
number = 5,
volume = 79,
place = {United States},
year = {Thu Sep 15 00:00:00 EDT 2016},
month = {Thu Sep 15 00:00:00 EDT 2016}
}
  • Inclusive double differential multiplicities [ital d][sup 2][ital N]/[ital dy] d[ital p][sub [ital t]] and related quantities have been measured for protons and deuterons produced in 14.6[ital A] GeV/[ital c] Si+Al and Si+Pb collisions using the E814 forward spectrometer at the AGS at BNL. Collision centrality'' is determined by measuring [ital N][sub [ital c]], the total charged particle multiplicity in the pseudorapidity range 0.85[lt][eta][lt]3.8. For both systems Si + Al and Si + Pb, an increase in the proton rapidity distribution [ital dN]/[ital dy] at midrapidity and a corresponding decrease at higher rapidities are observed with increasing [ital N][sub [ital c]].more » For Si+Pb, Boltzmann slope parameters [ital T][sub [ital B]] increase significantly in the most central collisions. The measured distributions exhibit a centrality dependence even when [sigma]/[sigma][sub geo][approx lt]10%, where full overlap between the Si and Pb nuclei occurs in a simple geometric picture. The proton rapidity distribution [ital dN]/[ital dy] is presented for the symmetric system Si+Al over the entire rapididty interval. The total number of protons, which is the integral of this quantity over rapidity, varies with [ital N][sub [ital c]]. Results are compared with various model calculations, mostly using the hadronic cascade codes ARC and RQMD. No significant nuclear transparency is observed, indicating that large baryon and energy densities are produced in these collisions.« less
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