Basic performance of a pressurized backgammon-type position-sensitive proportional counter for thermal neutrons

A position-sensitive proportional counter with the backgammon position-reading method has been developed for thermal neutron detection. The use of a thin solid layer of 10B and a high-pressure counting gas of 6-atm Ar+10%CH4 has enabled us to obtain the position resolution well below 1.0 mm. Moreover, it was clearly revealed that the deterioration and/or the splitting of position-peak structure, observed in some conditions, originated in the strong correlational behavior between position information and avalanche size. It is explained qualitatively that this phenomenon is caused by the effect of self-induced space charge.