Micro-hole & strip plate detector for neutron detection

We propose the use of argon-xenon penning-mixtures as the stopping gas, in substitution of carbon-based gases, in /sup 3/He neutron detectors. Such stopping gas presents a solution for the use of GEMS or MHSPs electron multipliers with suitable gains for neutron detection. With these mixtures it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. A MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2 × 10/sup 3/. This mixture allows neutron detection efficiencies of about 70% for a 2.5-cm thick absorption region and intrinsic position resolution (FWHM) of about 1.7-mm. Increasing the argon partial pressure to 6-bar, it is possible to reduce the detector intrinsic position resolution to 1-mm. The sensitivity to γ-rays will be the same when compared to that of 2.6-bar CF/sub 4/.