Using the FOPI facility at GSI Darmstadt complete data of Au on Au collisions at 150ital A MeV were collected for charged products (ital Z=1--15) at laboratory angles 1degreeleThetasub lable30degree. ...Central collisions were selected by applying various criteria. The kinetic energy spectra of fragments from an isolated midrapidity source are investigated in detail for center-of-mass angles 25degreeleThetasub c.m.le45degree. The heavy products (ital Zge3) are used to determine the collective energy which is found to be at least 10ital A MeV.
Charged particles have been observed in collisions of Au on Au at an incident energy of 150{ital A} MeV using a high-granularity detector system covering approximately the forward hemisphere in the ...center-of-mass system. Highly central collisions have been studied using a double selection criterion which combines large charged-particle multiplicities with small transverse-momentum directivities. In this class of events about one quarter of the total nuclear charge emerges as intermediate-mass fragments with nuclear charges {ital Z}{gt}2. These fragments are centered at midrapidity and are produced with large transverse velocities.
Velocity correlations of intermediate mass fragments (IMFs), produced in central collisions of Au+Au at 150 MeV beam energy, are extracted from measurements with the FOPI (phase I) detector system at ...SIS in GSI Darmstadt. The IMF correlation function for semicentral events is found to be affected by the directed sideward flow. When rotating the events into a unique reaction plane an enhancement of correlations, resulting from event mixing effects, vanishes. Selecting violent collisions with a high degree of azimuthal symmetry the correlation function appears nearly independent of additional event or single particle gate conditions. The comparison of the data with a Coulomb dominated final-state interaction model points to an expanding and multifragmenting soure with radius ital Rsimilar to14 fm.
