Gross and intermediate-width structure in the interaction ofO16withO16

Abstract

The complete fusion cross section and the individual yields of the 12 most abundant nuclides produced have been determined for the $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ system in the energy region from 30-40 MeV (c.m.). The individual production cross sections from this and an earlier experiment at lower energies are compared with the predictions of a spin-dependent evaporation model calculation. The comparison, though not completely satisfactory, nevertheless provides no evidence that such models are inadequate to explain the observations. The measured production cross sections are also used to deduce a new normalization for existing low-energy $^{16}\mathrm{O}$ + $^{16}\mathrm{O}$ reaction cross section data. Striking periodic gross structure observed in the complete fusion cross section is compared with the total reaction cross section predictions of the optical model, using several different potentials. Good agreement is obtained for surface-transparent and, in particular, angular-momentum-dependent potentials. Additional intermediate-width anomalies are identified at ${E}_{\mathrm{c}.\mathrm{m}.}=30.5, 35, \mathrm{and} 38.5$ MeV in the $^{16}\mathrm{O}$ (${3}^{\ensuremath{-}}$) and $^{20}\mathrm{Ne}$ channels.NUCLEAR REACTIONS Complete fusion, $^{16}\mathrm{O}$+$^{16}\mathrm{O}$, ${E}_{\mathrm{c}.\mathrm{m}.}=12\ensuremath{-}40$ MeV, measured $\ensuremath{\sigma}(E)$ for production of 12 nuclides; $\ensuremath{\gamma}$-ray measurement, Ge(Li) detectors and natural target; deduced total fusion $\ensuremath{\sigma}$; evaporation-model analysis of nuclide distribution; optical-model analysis of total reaction cross sections; extracted barrier and critical parameters; deduced new normalization for existing low-energy $^{16}\mathrm{O}$+$^{16}\mathrm{O}$ reaction cross sections.