Spin dipole and quadrupole resonances in 40Ca.

Angular distributions of the double differential cross section {ital d}{sup 2}{sigma}/d{Omega} dE({sigma}) and the spin-flip probability {ital S}{sub {ital nn}} have been measured for inclusive proton inelastic scattering from {sup 40}Ca at 319 MeV. Excitation energies ({omega}) up to about 40 MeV have been investigated over the angular range from 3.5{degree} to 12{degree} in the laboratory (0.3 to 0.9 fm{sup {minus}1}). Here, multipole decompositions of angular distributions of {sigma}{ital S}{sub {ital nn}} for the {sup 40}Ca({ital {rvec p}},{ital {rvec p}} {prime}) reaction at 319 MeV have been performed in order to compare {Delta}{ital S}=1 strength observed with sum rules. In contrast to the well-known quenching of Gamow-Teller and {ital M}1 resonances, the spin-dipole resonance has a total measured strength which is larger than that predicted by the energy-weighted sum rule. The spin-dipole strength distribution supports asymmetric widths predicted by calculations including 2p-2h mixing. The spin-quadrupole resonance is observed near {omega}=35 MeV and its total strength for {omega}{lt}40 MeV estimated.