Scattering of alpha particles by oxygen. I. Bombarding energy range 5.8 to 10.0 MeV

Abstract

Absolute differential cross sections for the elastic scattering of a particles by O¹⁶ have been measured as a function of bombarding energy in the range 5.8-10.0 MeV. Measurements were made at center-of-mass angles of 90.0°, 109.9°, 114.0°, 125.3°, 131.4°, 140.8°, 149.4°, 154.0°, 158.8°, and 163.8°. Detailed angular distributions have been measured at 6.97, 8.63, and 9.92 MeV (lab). Sixteen resonances have been observed corresponding to energy levels in Ne²⁰ at 9.50, 9.99, 10.30, 10.49, 10.55, ~10.7, 10.83, (10.93), 11.03, 11.29, ~11.6, (11.89), 11.99, 12.27, 12.39, and 12.58 MeV (c.m.). Spin and parity assignments have been made for six of these levels, tentative assignments are suggested for seven, and two or more possible assignments are given for two levels. Phase shifts have been extracted from the angular distribution data at 6.97, 8.63, and 9.92 MeV (lab). New rotational bands in Ne²⁰ are suggested by the data and previously reported bands have been extended. Information about the levels in Ne²⁰ is compared with that obtained in previous studies of other nuclear reactions. The correspondence with the results of an O¹⁶(α, γ )Ne²⁰ investigation is generally good. The set of Ne²⁰ levels found in this work is somewhat different from the set determined by the C¹²(C¹², α)Ne²⁰ reaction experiments, and this difference is discussed.