A Large Aperture Neutron Time-Of-Flight Spectrometer

Abstract We describe a large aperture 2 m × 2 m neutron time-of-flight spectrometer, consisting of 145 plastic scintillator blocks, each 270 mm deep and 153 × 153 mm 2 in area. We present details of the design, the construction and the on-line data acquisition and monitoring system. We briefly summarise its performance: detection efficiency ≳20%, time-of-flight and spatial resolution (standard deviation) ∼1.1 ns and ∼ 0.9 blocks respectively. The counter operated successfully for four years in conjuction with a high resolution electron spectrometer to measure electroproduction processes with a nucleon in the final state. Although it was designed for the detection of neutrons of kinetic energy between 30 and 500 MeV, it was well suited also for the detection of high energy protons.