Breakup temperature of target spectators in 197Au + 197Au collisions at E/A = 1000 MeV

Abstract

Breakup temperatures were deduced from double ratios of isotope yields for target spectators produced in the reaction 197 The good agreement with the breakup temperatures measured previously for projectile spectators at an incident energy of 600 MeV per nucleon confirms the universality established for the spectator decay at relativistic bombarding energies. The measured temperatures also agree with the breakup temperatures predicted by the statistical multifragmentation model. For these calculations a relation between the initial excitation energy and mass was derived which gives good simultaneous agreement for the fragment charge correlations.The energy spectra of light charged particles, measured at θ lab = 150• , exhibit Maxwellian shapes with inverse slope parameters much higher than the breakup temperatures. The statistical multifragmentation model, because Coulomb repulsion and sequential decay processes are included, yields light-particle spectra with inverse slope parameters higher than the breakup temperatures but considerably below the measured values. The systematic behavior of the differences suggests that they are caused by light-charged-particle emission prior to the final breakup stage. Keywords:197 Au projectiles and targets, E/A = 600 and 1000 MeV; measured fragment cross sections, isotopic yield ratios; deduced breakup temperatures, pre-breakup emission; analysis using quantum statistical and statistical multifragmentation models.

Theoretical study of projectile fragmentation in theSn112+Sn112and<

“…An ensemble of excited sources was assumed to represent the collision systems after the initial nonequilibrium part of the reaction and chosen as the starting configuration for the statistical description of the subsequent reaction stages. Its general form in the plane of source mass and excitation energy was adapted from previous studies [9][10][11] and the sensitivity of the experimental observables to the parameters required for the liquid-drop description of the primary excited fragments was evaluated [6]. With the present work, we demonstrate that the same approach can be used to describe the recent FRS data for similar projectiles and that comparable results concerning the required model parameters are obtained.…”

“…[8]] is a useful tool for describing the fragment production in peripheral heavy-ion collisions at high energy [6,10,11,18]. In the present work, we consider the ensemble approach with the same parameters that were used for the interpretation of the ALADIN data [6].…”

“…[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.…”

Evidence of phase transition in the break up of Kr-projectile nuclei at 0.95A GeV

“…On the other hand, it has been proposed that a back bending in the caloric curve that leads to a negative specific heat can be signed through the occurrence of abnormally large kinetic energy fluctuations. This signature of 1st order phase transition has been applied to a number of multi-fragmentation data and a liquid-gas phase transition has been tentatively identified, particularly at few hundred MeV/A [1,[14][15][16][17][18]. Also, considering the size of the heaviest fragment produced in each collision event as order parameter, a number of other groups [19][20][21][22][23][24][25] have studied the distribution of this order parameter for various systems at few to few hundred MeV/A.…”

Microcanonical studies concerning the recent experimental evaluations of the nuclear caloric curve

“…Consequently, we deal with an important nonequilibrium part included in the measured source excitation energies which may belong to both pre-equilibrium or pre-break-up stages [7]. The SMM calculations suggest a significant quantity of nonequilibrium energy even in the case of the 600 MeV/nucleon bombarding energy reaction [7][8][9].…”