Entry-level spin distributions and relative γ-neutron branching ratios of samarium isotopes populated by the (p,t) reaction

The spin distribution populated in the Sm-150(p, t) reaction with 25 MeV protons has been investigated using the silicon telescope and high-purity germanium array Hyperion. Angular distributions of outgoing tritons and relative intensities of gamma rays from low-lying levels are used to deduce the initial spin distribution using statistical calculations and are compared with a semiclassical model of the (p, t) reaction. Experimental and theoretical results suggest a peak strength near 4h when gated on outgoing tritons detected in Hyperion, while the full 4 pi distribution may peak near 2h. Additionally, the average gamma-neutron branching ratio is determined from the data with the aid of one of two new codes presented in this work. The analysis is extended to other recent studies of Sm-152,Sm-154(p, t) to form systematics of the spin-dependence of the surrogate method applied to heavy nuclei in the transitional to deformed region.