Forbidden transitions in the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(d, p){}_{}{}^{49}{}_{}{}^{}\mathrm{Ca}$ reaction

In a measurement of the angular distribution of proton groups from the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(d, p){}_{}{}^{49}{}_{}{}^{}\mathrm{Ca}$ reaction at $E_d=20\mathrm{}$ MeV, particular emphasis is placed on the observation of seven weak transitions to states below 5 MeV excitation. These distributions are analyzed using distorted-wave Born-approximation (DWBA) parameters fixed by fitting, at $E_d=13.0, 16.0, \mathrm{and} 19.3$ MeV, the angular distributions of the elastically scattered deuterons and the protons populating the single-particle $2p_{\frac{3}{2}}$, $2p_{\frac{1}{2}}$, and $1f_{\frac{5}{2}}$ states. The DWBA model also fits the ($d, p$) data of other investigators at $E_d=7.0\mathrm{} \mathrm{and} 10.0$ MeV. The same model is then applied to the seven weak transitions, for which earlier data are available at 7.5 and 10.0 MeV in addition to the new $E_d=20\mathrm{}$ MeV data. New partial angular distributions at 9.0 MeV are helpful in resolving some discrepancies. For three of the weak transitions, older $l$ assignments are confirmed, for two of them new $l$ assignments are made, and for two transitions the observed behavior is incompatible with any reasonable DWBA model. All seven transitions can be explained as populating 2p-1h states formed by coupling a neutron to excited states of the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ core.

NUCLEAR REACTIONS ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(d, p)$, $E_d=9, 13, 16, 19.3, 20$ MeV; measured $\sigma (E_p, \theta )$; deduced levels, $J$, $\pi$, $l$, spectroscopic factors. Enriched target.