TEMPERATURE AND EXCITATION ENERGY OF HOT NUCLEI IN THE REACTION OF AR-40+AU-197 AT 25 MEV/NUCLEON

摘要

The coincidence measurements between heavy fission fragments and light charged particles with Z less than or equal to 2 were carried out for the Ar-40 + (197)AU reaction at 25 MeVucleon, to study the properties of hot nuclei in heavy ion induced reactions, The linear momentum transfers (LMTs) were deduced from the folding angle and the time-of-flight difference between two fission fragments of heavy residues. The relationship of the nuclear temperature (slope parameter of the energy spectrum) and the excitation energy was determined independently from the measurement of the kinetic energy spectra in the frames of the emitting sources and from the LMT analysis. Both the temperature and the excitation energy increase with decreasing impact parameter, which suggests that a plateau temperature of 5.5 MeV is reached at an excitation energy of 3.1 MeVucleon. The result was also compared with various statistical models that explain the plateau by the multifragmentation process, where the excitation energy is assumed to be stored in compression and expansion effects. (C) 1997 Elsevier Science B.V. [References: 30]