ISOTOPIC YIELDS OF INTERMEDIATE-MASS FRAGMENTS EMITTED IN E/A=50 MEV HE-4+SN-116, SN-124 REACTIONS

Inclusive yields of isotopically resolved intermediate-mass fragments (IMF) with Z = 3-6 have been measured for the reaction of E/A = 50 MeV He-4 with Sn-116 and 124Sn targets. The isotopic yield patterns reflect the N/Z ratio of the target for both equilibriumlike and nonequilibrium components of the spectra. In addition, the IMF elemental cross sections for the Sn-124 target decrease much more rapidly with Z than for Sn-116. This effect is presumably due to lower barriers for IMF emission from residues formed with the neutron-deficient Sn-116 target and increased competition from pre-IMF neutron emission for the neutron-excess 124Sn target. The experimental cross sections are compared with statistical and accreting-source calculations.