We present new experimental data obtained with the FOPI detector at SIS, for the Au + Au heavy-ion collisions at 400
A MeV incident energy. The sideward flow, determined from a method without ...reaction-plane reconstruction, and the nuclear stopping are studied as a function of the centrality of the collisions. In order to study the nuclear in-medium effects, which act on the NN cross sections and potential and hence on experimental observables like the nuclear-matter flow and stopping, these results are compared with the predictions of two different QMD versions. The first one offers a fully microscopic calculation of the cross sections and potential in the G-matrix formalism and naturally includes the in-medium effects (this version is for the first time confronted with experiment). The second one uses a standard Skyrme potential plus a momentum-dependent term in order to mimic the in-medium effects.
Central Au on Au collisions Gobbi, Adriano; Alard, J.P.; Amouroux, V. ...
Nuclear Physics A,
02/1995, Letnik:
583
Journal Article, Conference Proceeding
The entropy per nucleon (ital S/ital A) has been extracted for the Au (150--800)ital A MeV + Au reaction by using the phase I setup of the 4pi facility at GSI, Darmstadt. The entropy has been ...obtained from the comparison of various observables characterizing the ital dM/ital dZ fragment multiplicity distributions, extending up to ital Zsimilar to15, with those calculated with the quantum statistical model. It is the first time that ital S/ital A values are determined by considering the full ensemble of charged products detected in the reaction. Consistent values of ital S/ital A are found from different methods. These entropy values are shown to be fairly independent of the volume of the participant'' region considered. They are somewhat lower than those extracted in earlier works but are in good agreement with hydrodynamic calculations and suggest a low viscosity for the hot and dense nuclear matter.
Light-particle emission from Au+Au collisions has been studied in the bombarding-energy range 100–250
A·MeV, using
ΔE−
E
R telescopes in coincidence with the FOPI detector in its
phase I ...configuration. Center-of-mass energy spectra have been measured for
Z = 1,2 isotopes emitted in central collisions at CM polar angles between 60° and 90°. Evidence for a collective expansion is reported, on the basis of the mean kinetic energies of hydrogen isotopes. Comparison is presented with statistical calculations (WIX code). For CM kinetic energy spectra, fair agreement is found between data and a recently developed transport model.
