Neutron Scattering Cross-Section and Analyzing Power Measurements for CALCIUM-40 and YTTRIUM-89 and Comprehensive Optical Model Analyses.

Differential cross sections (sigma)((THETA)) and analyzing powers A(,y)((THETA)) have been obtained for the scattering of neutrons to the ground and 3('-) excited states of ('40)Ca. These new measurements include (sigma)((THETA)) for (n,n(,0)) and (n,n(,1)) at 14 and 17 MeV, and A(,y)((THETA)) for both groups at 11, 14, and 17 MeV. The data complement earlier work performed at Triangle Universities Nuclear Laboratory (TUNL) for elastic scattering of neutrons from ('40)Ca between 10 and 14 MeV. The A(,y)((THETA)) measurements, as well as those for (sigma)((THETA)), were made using pulsed deuteron beams and the ('2)H(d,n)('3)He reaction as a source of neutrons. Both types of measurements were made using the TUNL, time-of-flight spectrometer. All data were corrected for the effects of flux attenuation, finite geometry, and multiple scattering. The combined set of neutron data has been described using the spherical optical model (SOM) and the coupled-channel (CC) optical model. In addition to these analyses a CC study was made in which many available proton data up to 200 MeV and total cross sections up to 80 MeV were incorporated as well, providing a much more comprehensive data base for determining the global properties of the optical model potential for the ('40)Ca + nucleon system over a wide energy range. In all the optical model studies, special emphasis was placed on the determination of the parameters that describe the spin-orbit interaction and the deformations of the central and spin-orbit potentials. The program of measuring differential cross sections and analysing powers for neutron scattering was also extended to include the nucleus ('89)Y in order to obtain more information about nucleon-nucleus elastic scattering in the mass region near A = 90. These new measurements consist of (sigma)((THETA)) data obtained at 8, 10, 12, 14, and 17 MeV, and A(,y)((THETA)) data at 10, 14, and 17 MeV. The results have been compared to predictions based on existing spherical optical models and to newly derived SOM parameter sets obtained in searches on the (sigma)((THETA)) and A(,y)((THETA)) data.