Structures in angular momentum gated proton and alpha particle spectra in low-energyan ~(12)C and ~(16)O induced reactions

摘要

Gamma-ray multiplicity gated proton spectra have been measured in the ~(12)C + ~(93)Nb and ~(16)O + ~(89)Y reactions producing the same compound nucleus ~(105)Ag at an excitation energy of __39.8 MeV, and in the ~(12)C + ~(89)Y reaction at E(~(12)C) = 40 MeV. Multiplicity gated alpha particle spectra have been measured in the ~(12)C + ~(93)Nb reaction at E(~(12)C) = 37.5-45 MeV. All these measurements were aimed at gaining more insight into the origin of the unexpected broad structures seen earlier in the high energy part of the proton spectra at high gamma-ray multiplicities. Two possible explanations, one of the enhanced nuclear level density within the statistical model and the other of a massive cluster transfer process, were suggested by us to understand the earlier data. The former prescription appears to be favoured by the present proton data.