Influence of amplifier time constant on proportional counter calibration

This note describes the observation of the effects of a particular electronic parameter on the calibration of proportional counters. The effect in question is well-known and in a sense obvious, but it is easily overlooked in some applications of proportional counters to microdosimetry. Therefore, it is thought worthwhile to recount an example where this problem did occur, with a view toward helping others avoid such difficulties in the future. The effect will be of greatest importance for large gas pressures and/or small electrode potentials (low gas gain), and for radiation modalities which exhibit a large dynamic range of energy deposition