Absolute Determination of Monoenergetic Neutron Flux in the Energy Range 1 to 30 Mev

Monoenergetic neutron fluxes can be measured at neutron energies above 1 Mev by observing recoil protons scattered at forward angles from a hydrogenous radiator. A counter telescope system for observing the recoil protons is described which has a relatively high efficiency for neutron detection. The major part of the paper is devoted to backgrounds and corrections, the calculation of telescope efficiency, and the accuracy of neutron flux measurements. Tables are given which make possible a simple determination of the efficiency of a counter system at neutron energies between 1 and 30 Mev. An appendix presents a semiempirical formulation of n-p scattering which is used in obtaining counter efficiencies.