Interactions of 2 GeV/Nucleon¹⁶O with Light and Heavy Emulsion Nuclei

Abstract

Heavy ion interactions in nuclear emulsions induced by 2 GeV/nucleon 16O have been studied. The reaction cross sections determined are 337-85 +56 mb, 1007-174 +175 mb and 2180-231 +304 mb for interactions with H, CNO and AgBr, respectively. Energy-, angular- and transverse momentum distributions of non-relativistic protons (E400 MeV) and all He nuclei have been analysed. Statistical models assuming small correlations among nucleon momenta can account for the main part of the He emission. The energy- and transverse momentum distributions of protons, emitted from light as well as heavy target nuclei indicate that intranuclear nucleon-nucleon scattering is the most important proton emission process. The angular distributions of both high energy protons and high energy He nuclei emitted from the target nucleus differ considerably in central and peripheral 16O-AgBr interactions. In order to explain the angular distributions of high energy protons and He nuclei in events with extremely small impact parameter, non-statistical phenomena, possibly hydrodynamic shock wave emission, must be considered.

The disintegration of nuclei in violent heavy ion interactions at 55A MeV-110A MeV

“…The velocity of the composite particle source is larger than that of protons. The velocities we find for the proton source are of the same order as one finds for central relativistic heavy ion collisions [22,29]. Naturally it is tempting to believe, that these particles originate from the same system as the heaviest final remnant since the two velocities are of the same order (fl< 0.02c).…”

“…Here cr R is the reaction cross-section. With reaction cross-sections from [22] we find bmax= 3.8 fm. Thus the maiofity of the events corresponds Emission angles (0), ranges (R) and dip angles (r i.e.…”

“…2a) are indica'ted with arrows. A dip angle correction of the kind discussed in [22] has been applied. Only 7% of all particles produce tracks with q;>60 degrees, where such a correction is not sufficient.…”

On the anomalon interpretation of40Ar + Cu collisions at 0.9 and 1.8 A GeV

“…where A, B and C are the target activities induced by the primary beam, by beam fragments, and by target fragments, and generated pions, respectively. According to Jacobson and Kulberg [7], the inelastic cross section of the interaction between 4~ ions and Cu, o, is 2.65.10 -24 cm 2, and the mean-freepath, 2, equals 4.5 cm. As a result, the primary beam attentuation is 0.2 for a copper thickness of 1 cm.…”

Heavy ion reactions at 75?100 MeV/nucleon

“…impossible to exclude particles emitted in processes other than spectator emission from the "kinematically allowed" fragmentation region and this means that the selection criteria for p, d and He (solid histograms in Figures 1, 3 and 4) are not quite comparable. For 160-emulsion nucleus interactions at 2GeV/n a ~flll ) value less than 0.02c is reported [10]. For non-peripheral t60-emulsion nucleus reactions, Heckman et al [11] report {/~il)=0.015 c at 2.1 GeV/n and ~/~il)=0.038 c at 0.2 GeV/n.…”