NEUTRON YIELDS FROM ACTINIDE–BERYLLIUM ALLOYS

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, nmax, on the alpha-particle energy, E, is described by the empirical formula nmax = 0.152 E3.65 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.