Total cross sections of nuclei for 280 Mev neutrons.

The measurement of 28O-Mev neutron cross sections of various nuclei is described. The neutron beam used results from 340-Mev protons in the 184-in. cyclotron striking a 2-in. Be target. The neutron detector consists of a double coincidence anthracene scintillation counter telescope which counts recoil protons scattered at 15 deg from a paraffin cylinder placed in the collimated neutron beam. A 2-in. Cu absorber placed between the counters assures that only protons of energy greater than 250 Mev are counted. The cross sections for all nuclei measured from Li to Pb are smaller than the corresponding cross sections measured at 90 Mev by factors between 0.5 and 0.6.