CROSS-SECTIONS FOR PRODUCTION OF NEUTRON-DEFICIENT ISOTOPES OF BI ANDPB IN THE REACTIONS CA-40-151,EU-153(EU)

Measurements have been carried out of the absolute cross sections of t he (xn) and (p,xn) channels in the reactions Ca-40 + Eu-151, Eu-153 in the range of excitation energies 40-70 MeV. Comparison of the experim ental cross sections with calculations using a modified version of the program ALICE has shown that satisfactory agreement can be obtained u nder the assumption of a significant reduction of the fission barriers of the neutron-deficient isotopes of Pb and Bi. The justification of this conclusion is examined in an analysis including the cross section s of the (xn) and (p,xn) channels of the reactions Ar-40+ + Ho-165, Mg -24, Mg-26, + Ta-181, Ca-40 + Tb-159, and Ar-40 + Tb-159.