Investigation of γ Rays following S - and P -Wave Neutron Capture in Tin Isotopes

The energies and intensities of $\ensuremath{\gamma}$ rays following slow-neutron capture in resonances in isotopes of tin have been studied. The angular distribution of $\ensuremath{\gamma}$ rays from capture in $P$-wave resonances in ${\mathrm{Sn}}^{118}$, ${\mathrm{Sn}}^{120}$, and ${\mathrm{Sn}}^{124}$ has been measured for several $\ensuremath{\gamma}$ rays in order to determine the spins and parities of initial and final states in the reaction. The following assignments for the resonances can be made: ${\mathrm{Sn}}^{117}$(38.8 eV, ${1}^{+}$), ${\mathrm{Sn}}^{118}$(45.8 eV, ${\frac{3}{2}}^{\ensuremath{-}}$) ${\mathrm{Sn}}^{120}$(426.9 eV, ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$), and ${\mathrm{Sn}}^{124}$(61.95 eV, ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$), The spins of eight final states in ${\mathrm{Sn}}^{119}$ are assigned by virtue of the nonisotropic angular distribution for $\ensuremath{\gamma}$ rays following $P$-wave capture. New data on the energy levels in ${\mathrm{Sn}}^{118}$, ${\mathrm{Sn}}^{121}$, and ${\mathrm{Sn}}^{125}$ are also presented. Results of the present work are compared with the results of ($d, p$) and other charged-particle reaction studies and theoretical calculations on the tin isotopes.