A design study of a 1-m2 Multi-Wire-Proportional-Chamber Position-Sensitive-Neutron-Detector (MWPC-PSND)

Abstract

Neutron detection by MWPC based on 10B4C coatings can surpass in performance the one utilising 3He-gas in terms of position resolution and count rate capability at similar detection efficiency [13]. The use of m2-size foils coated by 10B4C demands the development of a mechanical concept to avoid deformations of the neutron sensitive surface due to their own weight and the electrostatic forces resulting from high voltage for operation. To preserve a flat shape of the converter, a pressure gradient is applied between its both sides [4]. The design shall allow a stacking of detection modules consisting of sequenced elements [converter/x-y-multi-wire planes/converter] in few mm proximity. A multiple stacking of the detector modules is needed to accumulate a sufficient high detection efficiency for diffraction with thermal neutrons over the entire detector [2]. The MWPC is planned to have fifteen detection modules corresponding to an efficiency equivalent of 30 converters coated with 1.2 µm of 10B4C. Efficiency simulations of a converter coating thickness-profile from 0.6 µm up to 1.2 µm prognoses a conversion rate up to 50 % for thermal neutrons and the presented design parameters of the 1-m2 MWPC allow a position resolution of 2 mm.