Development of neutron chambers with improved electrode design

A boron-lined neutron chamber has been developed with improved electrode design. The use of suitably machined PEEK spacers at the ends of the electrodes resulted in better performance of the ion chamber. The performance of the ion chamber was compared with a similar detector developed earlier with alumina discs. Neutron sensitivity tests on both types of chambers at Apsara Thermal Column chamber showed a sharper knee in the case of the chamber with PEEK spacers due to well-defined volume and elimination of edge and fringe effects. Tests with a calibrated 60Co Teletherapy source at gamma intensity levels ranging from 900 to 3000 R/h showed an average gamma compensation factor of 3.8%. The corresponding value for chambers with the alumina discs was 11.5%. A plot of the compensation factor as a function of gamma flux, showed a much more pronounced variation in the gamma compensation factor in the earlier design using alumina discs.