Investigation of the Bohr-Independence Hypothesis for Nuclear Reactions in the Continuum: α+Co59, p+Ni62 and α+Fe56, p+Cl59

Abstract

Measurements were made of the energy spectra at various angles of protons and $\alpha$ particles emitted from the reactions of protons with ${\mathrm{Ni}}^{62}$ and $\alpha$ particles with ${\mathrm{Co}}^{59}$ to determine the extent to which the deexcitation of the reaction intermediate, ${\mathrm{Cu}}^{63}$ at 20.2-MeV excitation energy, is independent of its mode of formation. Similarly, the reaction intermediate ${\mathrm{Ni}}^{60}$ at 23.6 MeV was formed by protons on ${\mathrm{Co}}^{59}$ and $\alpha$ particles on ${\mathrm{Fe}}^{56}$, again to determine to what degree its deexcitation by proton and $\alpha$-particle emission is independent of its mode of formation. Small differences in the shapes of corresponding energy spectra [($p, p^{\prime }$) versus ($\alpha , p$), and ($\alpha , {\alpha }^{\prime }$) versus ($p, \alpha$)] 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 $\frac{\sigma (x, p)}{\sigma (x, \alpha )}$ for the proton entrance channel over that for the $\alpha$ 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.