Experience with position-sensitive neutron detectors at the Intense Pulsed Neutron Source

Abstract

At the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory, pulses of protons accelerated in a synchrotron produce pulses of fast neutrons via the spallation process in an enriched uranium target. After moderation, the resulting pulses of slow neutrons are directed into beams which serve a variety of neutron-scattering instruments. Currently there are thirteen neutron-scattering instruments in operation or under development at IPNS, and six of these use position-sensitive neutron detectors (PSDs). These PSDs are: a 30 cm × 30 cm, ∼3 mm resolution, neutron Anger camera area PSD with 6Li-glass scintillator; a 2.5 cm diameter, ∼0.7 mm resolution, microchannel-plate area PSD with 6Li-glass scintillator; a 20 cm × 20 cm, ∼5 mm resolution, 3He proportional-counter area PSD; a 40 cm × 40 cm, ∼4 mm resolution, 3He proportional-counter area PSD; a flat 20 cm long, ∼1.6 mm resolution, 3He proportional-counter linear PSD; and 160 cylindrical 3He proportional-counter linear PSDs, each of which is 1.27 cm in diameter and 60 cm long and has ∼14 mm resolution. These detectors, in addition to being position-sensitive, resolve the time of the neutron capture with ∼1 μs precision for neutron time-of-flight measurements. This paper will discuss these various PSDs with emphasis on the instrumental specifications and the reasons for the selection of the different types of PSDs, and will also discuss the observed performances of these PSDs.