NEUTRON YIELDS FROM ACTINIDE–BERYLLIUM ALLOYS

Abstract

The neutron yields from the reaction Be⁹(α, n)C¹² have been measured for several actinide–beryllium alloys. The values for the beryllium thick target neutron yield, derived from the measurements on alloys containing Pu²³⁹, Am²⁴¹, and Cm²⁴², are 60 ± 2, 74 ± 2, and 112 ± 3 neutrons per million alphas, respectively, when based on the Chalk River standard Ra²²⁶-α-Be source. The dependence of the thick target yield, n_max, on the alpha-particle energy, E, is described by the empirical formula n_max = 0.152 E^3.65 neutrons per million alphas. The yields for Ra-α-Be and Ac²²⁷-α-Be, calculated from the latter expression, are in reasonable agreement with the best observed yields from powder-compacted sources. For Po-α-Be, the calculated thick target yield of 67 neutrons per million alphas lies within the limits of error of the yield observed by several earlier workers.