Spallation Neutron Measurement by the Time-of-Flight Method with a Short Flight Path.

Abstract

The experimental method of measuring neutron production double-differential cross sections was tested at incident proton energies of 0.8 and 1.5 GeV with C and Pb targets. Neutrons were measured with liquid scintillators by the time-of-flight method. The use of very weak secondary beam forced us to take a typical flight path length as short as 1 m. Preliminary experimental consideration led to the results that the amount of back ground neutrons were made low by the short flight path measurement, and a two-gate integration method was suited for the pulse shape discrimination between high energy neutrons and gamma-rays. The cross sections were obtained in the neutron energy range up to 100 MeV with acceptable energy resolution. The experimental results obtained at the incident proton energy of 0.8 GeV were consistent with the data taken with much longer flight paths. It was confirmed that the time-of-flight method with bare detectors at the short flight path was reliably applicable to the spallation neutron measurement.