Studies of light charged particle emission from fission and ER reactions in the system 344 MeV Si-28+Sb-121 -> Tb-149 (E*=240 MeV)

Light charged particles (LCP) have been measured for the reaction 344 MeV S i-28 + Sb-121 in singles and in coincidence with evaporation residues (ER), fusion-fission fragments (FF), and other LCP. A major feature of this expe riment was the use of a gas-filled magnetic spectrometer in the forward dir ection to separate ER From the much more abundant yield of elastically scat tered projectiles and projectile-like fragments. The dominant sources of ev aporative H-1 and He-4 emission are the ER (approximately 75%), with the re mainder being largely associated with fission reactions. For these latter r eactions, most of the H-1 and He-4 can be well accounted for by evaporation from the composite system prior to fission and by evaporation from the pos tfission fragments. LCP emission cross sections were determined fur each id entified source, and a comparison has been made to previous studies, From t his comparison, indications were found for significant entrance channel eff ects, with the more asymmetric channels exhibiting much larger LCF cross se ctions. Statistical model predictions for ER emissions are in good agreemen t with observed LCP energy spectra, angular distributions, and integrated i nclusive and exclusive cross sections, with all calculations using the same unique set of model parameters. This result contrasts strongly with recent reports for light mass systems, where model calculations were unable to si multaneously reproduce all observables. (C) 2001 Elsevier Science B.V. All rights reserved.