Abstract
The energy distributions of the light charged particles evaporated from spin-aligned compound nuclei at high angular momenta formed in the reactions of 240 MeV ('40)Ar + ('nat)Se and 176.6 MeV ('20)Ne + ('150)Nd were studied using four different experimental techniques in order to determine the effects of nuclear deformation on the energies of the emitted particles. In the first experiment with the Ar + Se system, a planar multiplicity filter selected a range of orientations of the singular momentum vector. Isotropic in-plane and anisotropic out-of-plane angular distributions for both protons and alpha particles coincident with large in-plane multiplicities showed this effect. The second experiment used a total energy crystal to both align the nuclei and determine the angular momentum of the emitting system using the total gamma energy. An indication of a deformation was seen in the constant average alpha particle energy as a function of the initial angular momentum. This result contrasts with a statistical model prediction of increasing alpha energy. Another observation was the dominant emission of protons over alpha particles at the highest total gamma energies. Model calculations showed this could be the result of a single nucleon cascade to the entry state from the highest initial angular momentum states. The third and final experiment with the Ar + Se system used a multiplicity filter to select alignment and the total energy crystal to select regions of angular momentum. The effect of constant average alpha particle energy with increasing total gamma energy was again observed. Analysis of the energy distributions parallel and perpendicular to the angular momentum vector showed an enhancement of the low and high energy alpha particles emitted perpendicular to the angular momentum vector. The high energy effect is predicted by the model but the low energy enhancement is consistent with the effect of a deformation. The final experiment was performed using the spin spectrometer at Oak Ridge National Laboratory with the Ne + Nd system. Results from this experiment showed a definite effect of the deformation, with the emission of low energy alpha particles emitted perpendicular to the angular momentum axis enhanced over thos emitted parallel to it.
Adler, Lee Ala (1984). A search for deformation effects in the energy distributions of light charged particles emitted from aligned nuclei at high angular momentum. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -411168.