Heating of nuclei with energetic anti-protons

International audienceHigh-energy γ rays associated with the decay of the giant dipole resonance have been measured for two fusion reactions leading to the 140Sm compound nucleus at an excitation energy of 71 MeV. The observed yield increases with the asymmetry in the ratios of the number of neutrons to protons in the entrance channel. This is interpreted as resulting from giant dipole phonons excited at the moment of collision in an N/Z asymmetric reaction

Grenze der Anregungsenergie fuer Teilchenverdampfung heisser Kerne nach Fusionsreaktionen

Available from TIB Hannover: DW 6570 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Particle evaporation from hot nuclei with A less than or equal to 85 mainly prior to scission

We report on measurements of fusion fission fragments and evaporation residues from the reaction Ni 58 Al 27 at 835 MeV incident energy leading to compound nuclei A less than or equal to 85 with high excitation energies. In the case of fission the mass dependence of the velocity widths of separated fragments indicate that the evaporation of light particles predominantly occurs from the composite nucleus prior to scission. The fraction evaporated from the fully separated fragments after scission can be estimated to approximately 2

Limiting excitation energies in fusion evaporation reactions

The mass dependence of the critical excitation energy above which a hot nucleus does not decay any more by particle evaporation, has been studied in the mass range 75 less than or equal to A less than or equal to 130. The experimental values of the critical excitation energy have been obtained by means of a new integral method based on the analysis of the widths of the evaporation residue mass distributions as a function of the residue velocity. The obtained mass dependence appears to be stronger than expected by Various models and a predicted dependence on the ZIA ratio of the decaying nucleus seems to be confirme

Vaporization and multifragmentation in 1.2GeV antiproton induced reactions on Cu and Ag

With energetic antiproton-light-nucleus interactions it is possible to reach excitation energies exceeding nuclear binding energy. For 1.2 GeV $\bar P$ +Cu we observe the onset of vaporization at about 8 MeV/nueleon, but even at 15 MeV/nucleon the probability of vaporization is smaller than 15%. The threshold excitation energy for multifragmentation processes defined as the detection of at least 3 intermediate mass fragments is observed at about 4 MeV/nucleon for 1.2 GeV $\bar P$ + Cu and Ag. The probability of multifragmentation is small and even at excitation energy above the total binding energy not larger than 5% and 20% of the corresponding inclusive cross sections

Thermal excitation and decay of nuclei from antiproton-nucleus interactions at 1.22 GeV

The formation and subsequent decay of nuclei excted via the annihilation of 1.22 GeV antiprotons have been investigated at LEAR. This mode of exciting nuclei offers.......