Gamma decay of analog states in 49Sc: [formula omitted

Abstract

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 E p(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 ( E x = 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.