The response and sensitivity of low pressure proportional counters in radiation protection

The results are reported of calculations on the response and sensitivity of a spherical low pressure tissue-equivalent proportional counter of 1 cm diameter simulating a tissue diameter of 1 μm. The calculations are preliminary to the design of a personal monitor based on the low pressure proportional counter but may be used directly for the design of a reference instrument and indirectly in the design of an area monitor. For various monoenergetic neutrons, kerma and the dose distribution in LET are calculated in muscle and hence dose equivalent is derived. For the same neutron energies the event size distributions in the proportional counter are calculated and from these estimates of dose, dose equivalent and counter sensitivity are made. From these calculations, conclusions are drawn concerning the constraints to be placed on the use of these counters for personal monitoring.