Abstract
Neutron-diffraction patterns have been measured for isotopically enriched powder samples of calcite using both steady-state and pulsed-neutron techniques. Greatly enhanced precision over previous work has been achieved for and , while the results for , , and represent new data. The coherent scattering lengths deduced from these measurements have been employed in a more definitive analysis of primary electric-dipole gamma rays from thermal-neutron capture. In three cases Ca, , and ) the estimates from a spherical optical-model formulation of the direct-capture mechanism are in agreement with the experimental cross sections. In the theory overestimates the measured cross sections on average by about 60%; this divergence can be explained by considering the modifications to the theory due to collective vibrations of the core.
- Received 5 December 1988
DOI:https://doi.org/10.1103/PhysRevC.39.1297
©1989 American Physical Society