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Register a new userInvestigation of an angular distribution of protons in peripheral and central nucleus-nucleus collisions at the momentum of 4.2 A GeV/c
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The experimental results on the relation between the number of events, the angular distributions of protons and full number of protons are presented for ${}^{12}CC$-interactions at the momentum of 4.2 A GeV/c. The influence of nuclear fragmentation process on the results is also considered. The obtai- ned results confirm the assumption that there exist the critical phenomena among the central collisions and it is necessary to use a percolation approa- ch for the full description of the central collisions.
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Collective flow of protons and negative pions has been studied within the momentum region of $4.2 div 4.5$ AGeV/c ($E =3.4 div 3.7$ AGeV) for different projectile-target combinations involving carbon and, specifically, He-C, C-C, C-Ne, C-Cu and C-Ta. The data stem from the SKM-200-GIBS streamer chamber and from Propane Bubble Chamber systems utilized at JINR. The directed flow of protons grows dramatically in the carbon region when the counterpart nucleus grows in mass between He and Ta. The elliptic proton flow points out of the reaction plane and also strengthens as system mass increases. Within the reaction plane, the negative pions flow in the same direction as protons for the lighter of the investigated systems, He-C, C-C and C-Ne, and in the opposite direction for the heavier, C-Cu and C-Ta. The Quark-Gluon String Model reproduces observed changes in the flow with system mass.
The production of protons, anti-protons, neutrons, deuterons and tritons in minimum bias p+C interactions is studied using a sample of 385 734 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.9 GeV/c in transverse momentum and in Feynman x from -0.80 to 0.95 for protons, from -0.2 to 0.4 for anti-protons and from 0.2 to 0.95 for neutrons. Existing data in the far backward hemisphere are used to extend the coverage for protons and light nuclear fragments into the region of intranuclear cascading. The use of corresponding data sets obtained in hadron-proton collisions with the same detector allows for the detailed analysis and model-independent separation of the three principle components of hadronization in p+C interactions, namely projectile fragmentation, target fragmentation of participant nucleons and intranuclear cascading.
New data on the production of protons, anti-protons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic calorimeter. Inclusive invariant cross sections are obtained in intervals from 0 to 1.9 GeV/c (0 to 1.5 GeV/c) in transverse momentum and from -0.05 to 0.95 (-0.05 to 0.4) in Feynman x for protons (anti-protons), respectively. pT integrated neutron cross sections are given in the interval from 0.1 to 0.9 in Feynman x. The data are compared to a wide sample of existing results in the SPS and ISR energy ranges as well as to proton and neutron measurements from HERA and RHIC.
The PHENIX collaboration has measured high-$p_T$ dihadron correlations in $p$$+$$p$, $p$$+$Al, and $p$$+$Au collisions at $sqrt{s_{_{NN}}}=200$ GeV. The correlations arise from inter- and intra-jet correlations and thus have sensitivity to nonperturbative effects in both the initial and final states. The distributions of $p_{rm out}$, the transverse momentum component of the associated hadron perpendicular to the trigger hadron, are sensitive to initial and final state transverse momenta. These distributions are measured multi-differentially as a function of $x_E$, the longitudinal momentum fraction of the associated hadron with respect to the trigger hadron. The near-side $p_{rm out}$ widths, sensitive to fragmentation transverse momentum, show no significant broadening between $p$$+$Au, $p$$+$Al, and $p$$+$$p$. The away-side nonperturbative $p_{rm out}$ widths are found to be broadened in $p$$+$Au when compared to $p$$+$$p$; however, there is no significant broadening in $p$$+$Al compared to $p$$+$$p$ collisions. The data also suggest that the away-side $p_{rm out}$ broadening is a function of $N_{rm coll}$, the number of binary nucleon-nucleon collisions, in the interaction. The potential implications of these results with regard to initial and final state transverse momentum broadening and energy loss of partons in a nucleus, among other nuclear effects, are discussed.
Inclusive charged pion, kaon, proton, and deuteron production in 14.6 GeV/c proton-nucleus collisions measured by BNL experiment E802 is compared with results from the GEANT3, GEANT4, and FLUKA simulation packages. The FLUKA package is found to have the best overall agreement.
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