Capture reactions in the 40,48Ca+197Au and 40,48Ca+208Pb systems

Capture-fission cross sections for 40,48Ca+197Au and 40,48Ca+208Pb have been measured at beam energies ranging from 195 to 416 MeV. The fissionlike fragments were detected in a pair of position-sensitive multiwire proportional counters and were identified from measurements of position and time using two-body kinematics. The data taken at energies above the barrier (up to 2.4 times the Coulomb barrier) were analyzed in terms of the extra push model showing a strong dependence on the Ca isotope. This dependence was also observed at energies below the barrier, where the results have been interpreted using a schematic coupled-channel code