Abstract
Experiments carried out on the detection of slow neutrons from the () reaction in show an increasing number of low-energy neutrons beginning at an alpha particle energy of 4.3 Mev, and extending to 5.6 Mev. The energies and angular distribution of these neutrons for Mev have been measured using the polyethylene sphere-moderated neutron spectrometer. The results indicate a peaking in the forward direction and an energy distribution consistent with their origin from inelastic alpha-particle scattering leaving excited to the level at 1.75 Mev, which subsequently breaks up with neutron emission. At an alpha-particle energy of 5.11 Mev, the mean energy of these neutrons and the differential cross sections are: 0°(0.33 Mev, 22 mb/sr); 70°(0.21 Mev, 8 mb/sr); and 120°(0.07 Mev, 2 mb/sr). The neutron spectrum of a Pu-Be source has been determined to have a large number of low-energy neutrons with a peak intensity at 0.3 Mev.
- Received 18 December 1961
DOI:https://doi.org/10.1103/PhysRev.126.1794
©1962 American Physical Society