FISSION OF RELATIVISTIC SECONDARY BEAMS

A new method is described to study nuclear fission of short-lived radi oactive isotopes induced by electromagnetic excitations. Secondary bea ms of fissile nuclei were produced by fragmentation of U-238 projectil es at 1 A GeV. After being separated and identified in the fragment se parator of GSI they impinged on a secondary lead target. Nuclear-charg e distributions and total kinetic energies of fission fragments produc ed in low-energy fission have been measured for a number of neutron-de ficient uranium, protactinium, thorium, actinium and radium isotopes. First experimental results are presented.