Novel large-area thermal neutron imaging detectors comprising [formula omitted] and micro-strip gas detectors with low-pressure, two-stage amplification and delay line readout

Abstract

A novel large-area (0.5 × 0.5 m 2) two-dimensional position-sensitive detector for thermal and sub-thermal neutrons is being developed comprising 157 Gd CsI multilayer convertor foils and two fourfold segmented micro-strip gas detector (MSGC) planes for electron multiplication on either side of the convertor. The MSGC operates in low-pressure, two-stage amplification mode; their novel design is optimized for that mode and for obtaining high signals on both coordinates. Fast signal rise times (5–6 ns) and very high gains (∼ 5 × 10 5) are expected according to calculations; thus, simple delay line readout, with one interpolating strip between readout nodes, can be used delivering expected position resolutions <0.5 mm (fwhm) and tolerable count rates of 10 5–10 6 events/s depending on delay line segmentation.