Calculations of Inelastic Scattering of Neutrons by Heavy Nuclei

Abstract

Neutron-scattering cross-section data between 0.1 and 3.0 MeVforU, Th,Bi, Pb, Au, W,and Ta have been fitted using a local, spherical, spin-dependent optical potential with a minimum number of parameters. Total cross sections and differential elastic angular distributions, corrected to include compound elastic scattering, are used. With the ''entrance-channel" parameters thus determined, the Hauser-Feshbach statistical model gives reasonable predictions of the cross sections for inelastic scattering of neutrons by U 238 , Th 232 , Bi 209 , Pb 208 , Au 197 , W 184 , and Ta 181 . The latitude in fitting entrance-channel data allowed by the optical-model parameters is sufficient to mask effects arising from nonlocality, deformation, and width distributions. To a very high degree, this relatively simple model is shown to be

Small-Angle Scattering of Neutrons by Heavy Nuclei

“…16 The parameters of the optical model of Auerbach and Moore are the values given in Ref. 19. The results of these calculations for U at 1.2 MeV are given in Fig.…”

“…The potentials investigated were those of Rosen, 16 Perey and Buck, 17 Bjorklund and Fernbach, 18 and Auerbach and Moore. 19 In these models, the real well is represented by The parameters for the models of Refs. 16-18 are summarized by Rosen.…”

“…v(r)=-vf(r)-iw g (r)+vf-)[-/(r)l<r-l, (l)\MKC/ Lr dr J with /(r)={l+exp[(>-R)/a s ']}~1.The imaginary potential was of the surface-absorption type with the form factor g(r) given either as a Gaussian18,19 g(r) = exp£-(r-R)/ ad J,…”

Fast-Neutron Scattering From Tantalum, Rhenium, and Platinum.

“…Because of this limited experimental base, quantitative comparison with calculation has been difficult. [13][14][15][16][17][18][19][20] The low-energy excited structures of tantalum, rhenium, and platinum are characterized by collective rotational-vibrational and by singleparticle states.2 A wealth of structure information pertinent to these elements has been reported, particularly as the result of radioactive decay and Coulomb excitation s tudie s.…”