Studies of Fragment Angular Distributions inthe Fission of 197Au, 207Pb and 209Bi Induced by Alpha Particles of Energy up to 70 MeV

摘要

正The fission fragment angular distributions are measured with Lexan polycarbonate plastics for alpha-particle induced fission of gold, lead and bismuth. The measurements are made at several alpha particle energies between 40 and 70 MeV. At these energies, the relative differential fission cross sections for gold, lead and bismuth acting as targets are measured at several angles between 0° and 180° and the resulted angular distributions are fitted by least square method with Legendre polynomials. The anisotropies W（0°） / W（90°） at several alpha particle energies are measured for the above targets. These data are utilized in the calculation of the energy dependence of K₀2, the standard deviation of the distribution of the angular momentum projection on the nuclear symmetry axis at the saddle point. The integral cross section for alpha induced fission in each target is determined by numerical integration of the respective differential cross sections measured in the center of mass system. The results ar