An Assessment of Wall Effects in Microdosimetric Measurements

Proportional counters with solid walls exhibit distortions of pulse height distributions due to the so-called wall effects.With heavy charged particles these wall effects mainly affect the indirect events of energy deposition, i.e., those events where the heavy charged particle does not actually enter the cavity but merely injects some delta rays into it.The percentage of absorbed dose due to these distorted pulses is calculated for charged particles of different energy and for neutron fields.For neutrons below 10 MeV the wall effects are generally small, and conventional proportional counters are applicable.