Comparative study of multifragmentation of gold nuclei induced by relativistic protons, 4He, and 12C

Abstract

Multiple emission of intermediate-mass fragments has been studied for the collisions of p, 4 He and 12 C on Au with the 4π setup FASA. The mean IMF multiplicities (for the events with at least one IMF) are saturating at the value of 2.2 ± 0.2 for the incident energies above 6 GeV. The observed IMF multiplicities cannot be described in a two-stage scenario, a fast cascade followed by a statistical multifragmentation. Agreement with the measured IMF multiplicities is obtained by introducing an intermediate phase and modifying empirically the excitation energies and masses of the remnants.The angular distributions and energy spectra from the p-induced collisions are in agreement with the scenario of "thermal" multifragmentation of a hot and diluted target spectator. In the case of 12 C+Au(22.4 GeV) and 4 He(14.6 GeV)+Au collisions, deviations from a pure thermal break-up are seen in the energy spectra of the emitted fragments, which are harder than those both from model calculations and from the measured ones for p-induced collisions. This difference is attributed to a collective flow.

Multifragmentation with GeV light-ion beams

“…Values of source velocities similar to ours (0.01-0.02c) were reported by Avdeyev et al (2002) for the same interaction as examined in our work. But their results do not account for the existence of the transversal component of the V s .…”

Experimental signals of phase transition

“…A very good scaling behaviour is also obtained by comparing the presented sets of data and the charge distributions measured by the FASA collaboration for the reactions p, α + Au at 8.1, 4 and 14.6 GeV [7] and by the Indra collaboration for Xe + Sn reaction at 32 A MeV incident energy [8].…”

Theoretical study of projectile fragmentation in theSn112+Sn112and<

“…[8,21,22] is used. It represents the main version used previously for successful comparisons with a variety of experimental data [6,10,11,18,[23][24][25]. We calculate the contributions of all breakup channels partitioning the system into various species.…”