Particle-hole strength excited in the 48Ca(p,n)48Sc reaction at 134 and 160 MeV: Gamow-Teller strength.

Abstract

Gamow-Teller strength in the $^{48}\mathrm{Ca}$(p,n${)}^{48}$Sc reaction was studied at 134 and 160 MeV. Neutron energy spectra were measured by the time-of-flight technique with resolutions of about 320 and 460 keV, respectively. The cross sections reported at 160 MeV are increased (by a factor of about 1.4) from results reported previously. The ${1}^{+}$ Gamow-Teller strength is observed to be split into a low-lying state at ${E}_{x}$=2.52 MeV, the Gamow-Teller giant resonance in a complex of states between 4.5 and 14.5 MeV, and a single T=4 state at 16.8 MeV. The general distribution of the ${1}^{+}$ strength in $^{48}\mathrm{Sc}$ is in good agreement with a shell-model prediction. The total ${1}^{+}$ strength observed in discrete states amounts to 43% of the simple Gamow-Teller sum rule, relative to the observed ${0}^{+}$, Fermi strength assumed to be concentrated into the isobaric analog state at 6.67 MeV. Consideration of the \ensuremath{\Delta}l=0 contributions to the background under the Gamow-Teller giant resonance and of the non-quasifree scattering contributions to the continuum (up to about 30 MeV) increases this fraction to about 70%. Possible Gamow-Teller strength in the quasifree scattering contributions to the continuum is discussed.