The average-resonance-neutron-capture spectra of ${}_{}{}^{147}{}_{}{}^{}\mathrm{Sm}(n,\gamma ){}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{149}{}_{}{}^{}\mathrm{Sm}(n,\gamma ){}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ obtained with the Argonne in-pile ($n,\gamma$) facility are used to develop and extend the level schemes of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$. In particular, the experiment gives information about the spin and parity assignments of 33 levels with excitation energies from 0 to 2.7 MeV in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and 47 levels from 0 to 2.5 MeV in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$. Unique spin and parity assignments are given for almost all the states below 2.2 MeV in both isotopes. In many cases in which previous experiments gave conflicting indications, the new data led to definite spin assignments. The neutron binding energies in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ were found to be 8140.6±1.8 and 7986.4±1.8 keV, respectively, after correction for the energy spectrum of the captured neutrons.

• Received 11 May 1970

DOI:https://doi.org/10.1103/PhysRevC.2.1513