Nuclear structure of 48Ca.

Abstract

The states of $^{48}\mathrm{Ca}$ were studied by proton inelastic scattering at ${E}_{\mathrm{p}}$=65 MeV with an energy resolution of about 15 keV. The spectra obtained were highly structured and about 200 discrete levels were identified up to the excitation energy of 13.6 MeV. The widths of these levels were not noticeably wider than the instrumental energy resolution, even in the high excitation energy region above the neutron threshold. The values of transferred angular momentum L were assigned for most of the levels. The low-energy octupole resonance was observed as clustering L=3 states at the excitation energy between 7 and 12 MeV. In addition, many L=2 states and several L=0 states were observed above excitation energies of 10.5 and 12 MeV, respectively. These states are most likely the lower tails of giant quadrupole resonance and giant monopole resonance, respectively. Several unnatural parity states were clearly identified by comparing the (p,p') spectra with (\ensuremath{\alpha},\ensuremath{\alpha}') spectra obtained at a few angles. The spin and parity of each of these states were assigned with the aid of microscopic distorted wave analysis. Several states prominent at backward angles were identified to be high-spin stretched or nearly stretched states.