Damping of Unbound Single-Particle Modes

S. FORTIER; D. BEAUMEL; S. GALÈS; J. GUILLOT; H. LANGEVIN-JOLIOT; H. LAURENT; J.M. MAISON; J. BORDEWIJK; S. BRANDENBURG; A. KRAZNAHORKAY; G.M. CRAWLEY; C.P. MASSOLO; M. RENTERÍA; A. KHENDRICHE

PHYS. REV. - C

AMER PHYSICAL SOC

Lugar: New York; Año: 1995 vol. 52 p. 2401 - 2414

0556-2813

The (α,3He-n) reaction has been investigated at 120 MeV incident energy on Ni64, Zr90, and Sn120 target nuclei. Neutrons in coincidence with He3 particles emitted at 0° were detected using the multidetector array EDEN, in order to get information about the decay of single-particle states embedded in the (α,3He) continuum. Neutron angular correlations, multiplicity values, and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Evidence for a significant nonstatistical decay branch has been observed in the three nuclei below about 15 MeV excitation energy. Direct branching ratios in Zr91 deduced from this analysis are compared with the predictions of two nuclear structure models. At higher excitation energy, the decay characteristics of the (α,3He) continuum are shown to be mainly statistical.