Problems in neutron dosimetry associated with the incorrect composition of tissue-equivalent gas

The effects of varying tissue-equivalent gas composition in a tissue-equivalent ionisation chamber were investigated. Problems associated with the use of silicone rubber tubing in the gas flow system due to the leakage of carbon dioxide throught the wall of the tube are reported. Possible errors and discrepancies in th calibration of the tissue-equivalent chamber due to differences in the composition of the gas mixture are discussed.