Hot nuclei as viewed through 4π neutron multiplicity filters

Several aspects of hot nuclei are examined in the present review article. After defining what is usually meant by hot nuclei, the new tools which have been developed in order to determine the temperature are described. Using several examples, it is demonstrated that the 4π neutron multiplicity filters constitute a powerful and reliable means for nuclear temperature measurements. So far, hot nuclei have been essentially investigated through nucleus-nucleus collisions. The conditions of formation of hot nuclei in such collisions, as a function of the entrance channel parameters (bombarding energy, mass asymmetry, impact parameter) are studied in detail. Two specific decay channels of hot nuclei: binary fission and emission of intermediate mass fragments, as well as the combined effect of temperature and spin are reviewed. It is shown that energetic light particles can also be successfully used to generate hot nuclei. Such nuclei left with little initial compression and spin are of special interest in order to investigate the effect of heat and only heat on the properties and on the fate of nuclei. This is not possible in nucleus-nucleus collisions. Prospects are finally given, with the annihilation of energetic antiprotons in nuclei appearing as the most promising method of reaching the limiting temperature that a nucleus can sustain. (Author)