Heating of Nuclei with Energetic Antiprotons

The annihilation of energetic (1.2 GeV) antiprotons is exploited to deposit maximum thermal excitation (up to 1000 MeV) in massive nuclei (Cu, Ho, Au, and U) while minimizing the contribution from collective excitation such as rotation, shape distortion, and compression. Excitation energy distributions $d\sigma /{\mathrm{dE}}^{*}$ are deduced from eventwise observation of the whole nuclear evaporation chain with two $4\pi$ detectors for neutrons and charged particles. The nuclei produced in this way are found to decay predominantly statistically, i.e., by evaporation.