A measurement of the efficiency for the detection of neutrons, in the momentum range 200-3200 MeV/c, in large volume liquid scintillation counters

A system of 194 large volume liquid scintillation counters designed to detect neutrons in an experiment on the reaction π-p→π0n in the resonance region is described. The detection efficiency of the system has been determined, as a function of neutron momentum, in three separate measurements, covering the range 200-3200 MeV/c. Below 400 MeV/c the efficiency shows the expected momentum dependence near threshold, rising to a maximum of 50% near 300 MeV/c and then falling to 43% near 400 MeV/c. In the region 400-700 MeV/c the efficiency rises to 47% near 600 MeV/c and falls again to 43%, an effect not seen before; the efficiency was expected to be almost momentum independent in this region. Above the threshold for inelastic processes in nucleon-nucleon collisions approximately 800 MeV/c) the efficiency rises significantly reaching a maximum value of 65% above 1700 MeV/c. (Auth.)