Application of a continuous channel electron multiplier for measuring gaseous tritium at low pressures

Some fundamental studies on the application of a continuous channel electron multiplier (channeltron) for monitoring gaseous tritium present in an evacuated vessel at low pressures below 10(-4) Torr were carried out. The results showed that at the tritium pressures lower than 10(-6) Torr the tritium counting rate measured by the channeltron increased linearly, in practice, with increasing tritium pressure, as was expected by assuming that the interactions between beta-particle emitted from tritium and the vessel wall and gaseous molecules during the migration of beta-particle to the channeltron can be ignored. However, in the range of pressures over 10(-5) Torr the measured tritium counting rate was found to be getting smaller than the expected with increase in tritium pressure. This is presumably due to the absorption and scattering of beta-particles by gaseous tritium.