The influence of shell effects on the fissility of neutron deficient uranium isotopes at N ≃ 126

Production cross sections and excitation functions of neutron deficient isotopes of U, Pa and Th have been measured in the reaction of 22 N e+ 208 P b. The comparison of experimental production cross sections of uranium isotopes with the neutron number 126 ≤ N ≤ 134 to the values calculated using statistical model of nuclear deexcitation has been carried out. There is shown, that none of the commonly used methods of introduction of shell effect influence on the production cross sections of evaporations residues allows to reproduce unambigiously used set of experimental data. Simple semiempirical method of introduction of shell effect influence in fission channel is proposed and good agreement with production cross sections of neutron deficient isotopes in the region from Bi to U is reached.