Charged-particle calorimetry of 40Ar + 27Al reactions from 36 to 65 MeV/u

Abstract

Temperatures and excitation energies have been independently determined for hot nuclei formed in the 40Ar + 27Al reaction at energies ranging from 36 to 65 MeV/u. Charged products have been measured in a geometry close to 4π in the center of mass with the multidetectors MUR and TONNEAU. Events were sorted as a function of the impact parameter and the products emitted from equilibrated nuclei were separated from both pre-equilibrium and target-like products. Temperature (slope parameter) and excitation energy values were deduced from the kinetic energies of particles in the frame of the reconstructed equilibrated nucleus. Both have been found to increase with decreasing impact parameter. For the most central collisions impact parameters — less than 2 fm — the temperature was seen to increase with incident energy (slowly above 45 MeV/u) and reach a value of 7 MeV at 65 MeV/u. The excitation energy per nucleon exhibited a similar behaviour. The correlation between excitation energy and temperature was found to remain compatible with the statistical theory.