Measurement of Cross Sections of Heavy Fragments Formed in the Interaction of 0.65-12.7 GeV 4He with 209Bi

Formation of heavy fragments in the fission mass region during the interaction with 209Bi of the 0.65, 1.74, 5.1, 8.8 and 12.7 GeV 4He is studied using a sandwich configuration of the Makrofol polycarbonate track detector. Events are analyzed in which at least one heavy fragment is detected. Fragments produced in the experiment are identified and a model-free event-by-event analysis is performed in order to separate different production mechanisms. The cross sections and experimental features are determined for these reaction mechanisms, and so are their variations with the incident energy. Results are compared to the corresponding proton interaction data. (author)