Energy Levels inSm148andSm150

Abstract

Energy levels in ${\mathrm{Sm}}^{148}$ and ${\mathrm{Sm}}^{150}$ have been observed via the reactions ${\mathrm{Sm}}^{147}(d, p){\mathrm{Sm}}^{148}$, ${\mathrm{Sm}}^{149}(d, p){\mathrm{Sm}}^{150}$, ${\mathrm{Sm}}^{148}(p, p^{\prime }){\mathrm{Sm}}^{148}$, and ${\mathrm{Sm}}^{150}(p, p^{\prime }){\mathrm{Sm}}^{150}$ at 12-MeV bombarding energy. Reaction products were analyzed in a 0.1% energy resolution magnetic spectrograph using emulsion techniques. Levels below 1.9-MeV excitation are found to have much smaller ($d, p$) cross sections than those above this energy. Many previously unknown levels above 1-MeV excitation have been found in both these nuclei. The observed levels are compared with previous studies of these nuclei. Several of the positive parity levels in ${\mathrm{Sm}}^{148}$ can be fitted to an asymmetric rotor-vibrator spectrum. The excited states in ${\mathrm{Sm}}^{150}$ can be approximated, but not fitted exactly, with this model. The observed low-lying states in these nuclei are discussed in terms of expected level structure for collective models. The ground-state $Q$ values for the reactions ${\mathrm{Sm}}^{147}(d, p){\mathrm{Sm}}^{148}$ and ${\mathrm{Sm}}^{149}(d, p){\mathrm{Sm}}^{150}$ are determined to be 5920±10 keV and 5764±4 keV, respectively.