Neutron Transfer Reactions for Deformed Nuclei Using Sturmian Basis States

الأصل · EN

We study the spin-parity distribution P(Jπ,E) of ¹⁵⁶Gd excited states above the neutron separation energy Sₙ=8.536 MeV 156Gdₗistₒfₗevels that are expected to be populated via the 1-step neutron pickup reaction ¹⁵⁷Gd(³He,⁴He)¹⁵⁶Gd. In analogy with the rotor plus particle model Bohr&Mottelson-II, we view excited states in ¹⁵⁶Gd as rotational excitations built on intrinsic states consisting of a neutron hole in the ¹⁵⁷Gd core, that is, a neutron removal from a deformed Woods-Saxon type single-particle state Woods-Saxon:1954 in ¹⁵⁷Gd. The particle-core interaction usually dominated by a Coriolis coupling are accounted via first order perturbation theory VGGueorguiev:07062002. The reaction cross section to each excited state in ¹⁵⁶Gd is calculated as coherent contribution using a standard reaction code CHUCK based on spherical basis states. The spectroscopic factor associated with each state is the expansion coefficient of the deformed neutron state in a spherical Sturmian basis along with the spherical form factors VGGueorguiev:07062002. The total cross section, as a function of the excitation energy, is generated using Lorentzian smearing distribution function. Our calculations show that, within the assumptions and computational modeling, the reaction ³He+¹⁵⁷Gd → ⁴He+¹⁵⁶Gd⋆ has a smooth formation probability P(Jπ,E) within the energy range relevant to the desired reaction ¹⁵⁵Gd+n → ¹⁵⁶Gd⋆. The formation probability P(Jπ,E) resembles a Gaussian distribution with centroids and widths that differ for positive and negative parity states.