Light-particle evaporation as a function of neutron excess for medium-mass compound nuclei with Ex∼2 MeV/u

Light-particle emission from the fission reactions of 63Cu+92,100Mo and 20Ne+ 144,148,154Sm has been studied using the Texas A and M Neutron Ball detector. Linear-momentum transfers (LMT) were determined from fission-fragment-folding-angle measurements. An increase of neutron multiplicity with apparent linear-momentum transfer was seen. The initial excitation energies of the compound nuclei are estimated from the observed linear-momentum transfer and also reconstructed from the measured multiplicities and average energies of neutrons, protons and α-particles. The results of the two methods are in good agreement. The observed neutron multiplicities show a strong increase with increasing neutron-to-proton ratio of the composite system. The light-particle multiplicities are compared with calculated values using the statistical code GEMINI. The effect of the dynamic fission delay on the total light-particle multiplicities is explored and f ound to be small. ((orig.))