De-excitation of compound nuclei with A around 56: reduction of the emission barriers for protons and alpha particles
Sektion Physik, University of Munich, D-85748 Garching, Germany
Received: 15 June 1998 / Revised version: 5 November 1998 Communicated by C. Signorini
This paper contributes to the discussion on the phenomena of the enhanced emission of low-energetic charged particles during compound nuclei decay. The decay of compound nuclei 52Fe, 56Ni, and 59Cu was studied. Energy spectra and emission angles of evaporated charged particles were measured in coincidence with gamma rays to determine the corresponding evaporation residue nucleus. Additionally, evaporation residue distributions were determined with the Munich rf recoil spectrometer. In this way, detailed channel-specific evaporation data were obtained for theoretical analysis. We extracted evaporation barriers and compared them with corresponding fusion barriers. The main result was revealed to be a lowering of the evaporation barrier for protons and alpha particles relative to the fusion barriers. But the observed effect is not as intensive as reported in recent studies.
24.10.-i Nuclear-reaction models and methods - 25.60.Pj Fusion reactions - 25.70.Gh Compound nucleus