Search

Gamma rays have been observed from the 48Ca(p, γ) reaction de-exciting analogs of the 4.005 MeV ( f 5 2 ) and 4.024 MeV ( g 9 2 ) states in 49Ca. The resonances were observed at Ep(c.m.) = 5.933 ± 0.005 and 5.992 ± 0.005 MeV, respectively, with total widths 39 ± 5 and 18 ± 5 keV. The corresponding ground-state γ-widths were inferred to be 17 ± 5 and 22−11+22 eV. Decays of the lower resonance to excited states of 49Sc were also observed. A tentative lower limit of 1.7 eV was placed on the width of the transition to the 3 2 − (3.08 MeV ) level. The upper ( 9 2 + ) γ-ray (g.s.) resonance is depleted by a factor of 10–20 by the giant dipole resonance and cannot be used easily to extract structural information. The (tentative) lower limit on the M1 decay of the lower ( 5 2 − ) resonance to the 3 2 − state (Ex = 3.08 MeV) implies a strong 1 f 5 2 neutron admixture in the lower state which is not borne out by theoretical estimates of the effects of the core polarization. The M1 decay of this same resonance to the ground state is calculated to be 9–13 eV, with the Arima-Horie estimate for the effects of core polarization, and 16 eV in a three-particle, two-hole configuration mixing shell-model calculation. Both figures are consistent with the measurement and confirm the existence of strong magnetic moment renormalization effects.

The reaction 6Li(16O, d)20Ne has been studied at E 16 O = 20.0 MeV . Angular distributions were obtained for levels in 20Ne up to 6.72 MeV. Estimates of reduced α-particle widths were derived by estimating the direct reaction contribution to the cross section and by comparison to (α, α) scattering results.

The charge exchange reactions 26Mg(3He, t)26A1 and 30Si(3He, t)30P have been studied at 17.85 MeV bombarding energy. Angular distributions were obtained for transitions leading to levels up to 2547 keV in 26A1 and 3020 keV in 30P. The 1760 keV level of 26A1 was not excited. The data are analyzed with a microscopic model DWBA code that included a tensor force in addition to the central forces. The inclusion of the tensor part of the interaction permits fitting the non-analog transitions.

Targets of 14 N and 14 C were bombarded with 14.5 MeV protons. The 14 N was in the form of natural N 2 gas, which is 99.6% 14 N, while the 14 C was in the form of CO 2 with a 14 C enrichment of 91.4%. Particles from the (p, p'), (p, d) and (p, t) reactions on these nuclei were identified and analyzed using conventional solid-state detectors and electronics. The overall energy resolution was 70 keV. Angular distribution were taken from 20° to 150° for the (p, p′) reaction and from 20° to 110° for the (p, d) and (p, t) reactions. For 14 N, 18 levels were seen below 10 MeV excitation energy in the (p, p') reaction and one transition to the ground state of 13 N in the (p, d) reaction. The (p, t) reaction is energetically forbidden. For 14 C, 5 levels were seen below 8.5 MeV excitation but is was not possible to obtain angular distributions because of masking due to excited states of 16 O. Also for 14 C, 3 levels were seen in the (p, d) reactions and the (p, t) reaction leading to the ground state of 12 C. The (p, p′) data were analyzed assuming a microscopic model of the nucleus and a two-body interaction, which included a tensor component for the study of the 2.31 MeV level of 14 N. The DWBA code DRC was used for the (p, p′) analyses. The (p, d) data were analyzed using the code DWUCK to extract spectroscopic factors.