Statistical Multifragmentation in Central Au+Au Collisions at 35 MeV/u

Multifragment disintegrations, measured for central Au + Au collisions at E/A = 35 MeV, are analyzed with the Statistical Multifragmentation Model. Charge distributions, mean fragment energies, and two-fragment correlation functions are well reproduced by the statistical breakup of a large, diluted and thermalized system slightly above the multifragmentation threshold.Comment: Latex file, 8 pages + 4 postscript figures available upon request from [email protected]

Multifragment production in Au+Au at 35 MeV/u

Multifragment disintegration has been measured with a high efficiency detection system for the reaction $Au + Au$ at $E/A = 35\ MeV$. From the event shape analysis and the comparison with the predictions of a many-body trajectories calculation the data, for central collisions, are compatible with a fast emission from a unique fragment source.Comment: 9 pages, LaTex file, 4 postscript figures available upon request from [email protected]. - to appear in Phys. Lett.

Position determination and resolution of two-dimensional position-sensitive solid-state detectors

The determination of the coordinates of the incidence position on large solid state detectors, where the position sensitiveness is due to resistive electrodes, is discussed. A method to extract the x and y values from the signals at the corners of the resistive layer is described and tested. The results have been checked with different detectors and a variety of energies and ion beams

Angular and velocity analysis of the three-fold events in the Xe + Cu reaction at 45 MeV/u

An analysis of the angular and velocity distributions of the intermediate mass fragments produced in the reaction Xe + Cu at 45 MeV/u is presented. Events coming from central collisions are selected and compared with predictions of different models based on a statistical deexcitation of an equilibrated source. The angular and velocity correlations show that the experimental production of three nearly-equal mass fragments cannot be explained by a sequential binary decay and is compatible with a multifragmentation mechanism

Production of three nearly equal mass fragments in the Xe + Cu reaction at 45 MeV/u

An experimental study of three intermediate mass fragment production in the reaction Xe+Cu at 45 MeV/u is presented. Results are compared with the predictions of a conventional statistical binary decay model starting from equilibrated sources obtained both from incomplete fusion systematics and from dynamical calculations at several impact parameters. The inclusive experimental data agree with the dynamical predictions, whereas a disagreement between the exclusive data and the calculations has been found

A signal of spinodal decomposition around Fermi energy

Using thermal photons to tag the reaction time a prompt IMF emission component has been identified in central Ni-58 + (197)An collisions at 45 MeV/amu. The comparison with theoretical calculations supports the hypothesis of dynamical emission in the spinodal regio

Towards a better understanding of hard photon emission in intermediate energy heavy ion collisions

High energy photon spectra have been measured in several 58Ni induced reactions at 30A MeV incident energy. A two source analysis of the data has been performed using a two exponential parameterization of the associated gamma spectra. The relative intensity of the two components has been deduced as a function of the total mass of the interacting system and of the impact parameter. To attempt a characterization of the emission sources, correlations between photons and IMF's have been measured for the first time

Energetic Proton Emission in Heavy Ion Collisions at Intermediate Energy: Pre-Equilibrium and Cooperative Effects

Energetic proton emission has been investigated as a function of the centrality in the reaction Ni-58 + Ni-58 at 30 AMeV. Protons with energy extending up to a relevant fraction of the total available energy in the reaction were measured and studied. The dependence on the reaction centrality has been extensively investigated and data have been compared with the results of microscopic transport calculations. The more striking observation concerns the extremely energetic proton (E-P(NN) greater than or equal to 130 MeV) multiplicity which is found to increase almost quadratically with the number of participant nucleons thus indicating the onset of a mechanism beyond one and two-body dynamics

Nuclear temperature measurements with helium isotopes

Temperatures extracted with the family of (He-3, He-4) isotope ratio thermometers, T-He, have been studied and cross-checked with temperatures, T(He-4*) constructed from excited and ground state populations of He-4. Empirical correction factors provide baseline corrections for sequential decay effects for T-He < 4.5 MeV, independent of projectile, target and incident energies. After corrections for fluctuations due to sequential decay, statistical calculations predict that T-He, and T(He-4*) should agree. (C) 1998 Published by Elsevier Science B.V. All rights reserved