Instrumentation for Fast Neutron Time-of-Flight Studies

In connection with a continuing program of fundamental research concerning the scattering of fast neutrons, instrumentation has been developed for measuring the energies of 1-4 mev neutrons by means of their flight time over a one-meter path. Some problems involved in measuring the resultant 30-70 mμsec time intervals with an accuracy of a few per cent are discussed, together with the limitations imposed by intensity considerations, presently available photomultipliers, and known electronic recording techniques. Some results are given showing the spectra of neutrons scattered from a primary energy of 4.3 mev by zirconium, carbon, nickel, aluminum, and chromium.