Investigation of shell effects for heavy fissionable nuclei by the blocking technique

Abstract The crystal blocking technique has been used to measure delay times in the fission channel for excited nuclei produced in the 28 Si + nat Pt reaction. Experimental results range from 10 −17 to 10 −18 s at bombarding energies from 140 to 170 MeV. It is shown that fission barriers keep their double-humped structure for temperature up to 1.7–1.8 MeV, and that the lifetimes of excited states in the second potential well contribute essentially to the observed delay times in the fission channel.