Investigation of the Bohr-Independence Hypothesis for Nuclear Reactions in the Continuum:α+Co59,p

Abstract

Measurements were made of the energy spectra at various angles of protons and a. particles emitted from the reactions of protons with Ni 62 and a. particles with Co 59 to determine the extent to which the deexcitation of the reaction intermediate, Cu 63 at 20.2-MeV excitation energy, is independent of its mode of formation. Similarly, the reaction intermediate Ni 60 at 23.6 MeV was formed by protons on Co 59 and a. particles on Fe 56 , again to determine to what degree its deexcitation by proton and a-particle emission is independent of its mode of formation. Small differences in the shapes of corresponding energy spectra {_{p, p') versus (a, p), and (a, a.') versus (p, a) ] that were observed in apparent violation of the Bohr-independence hypothesis are removed after account has been taken of the effects of angular-momentum conservation. The observed enhancement of the ratio of cross sections a(x } p)/cr{x ) a) for the proton entrance channel over that for the a entrance channel cannot be interpreted in terms of angular-momentum conservation. The consequences of the possibility of isotopic-spin conservation, when considered, lead to enhanced proton reemission similar to that observed experimentally.

Comparison of proton and neutron spectra: The extended Griffin model, pairing and isospin

“…Previous work has indicated that isospin is conserved to a significant extent (at least 40-900/0) in reactions in this energy range in both the nickel [24][25][26] and tin [9] mass regions. Therefore, as a first approximation, complete isospin conservation has been assumed in these calculations.…”

Excitation functions of nuclear reactions producing11C

“…However, for light target nuclei the dominance of the compound nucleus contribution to %, although reasonable [31], is more questionable than for nuclei with A>40, cf. [32,33]. Special attention was given to the selection of the optical model parameters from the compilation of Perey and Perey [34].…”

Particle spectra from reversed kinematics: Powerful probes of hot rotating nuclei

“…6 constitute strong signatures for compound-nucleus evaporation. In addition, the results of [5][6][7] (Figs. 4 and 5) also indicate the dominance of evaporation for similar reactions in the same c.m.…”

“…These experiments demonstrated the validity of the "independence hypothesis" for the light particles observed in the backward hemisphere [5][6][7][8][9]. In addition, more detailed features of the evaporation processes were measured such as decay probabilities versus spin zone of the emitters [-7, 9-11].…”