Event Simultaneity in Cavities: Theory of the Distortions of Energy Deposition in Proportional Counters

The so-called wall effects are distortions of the statistics of energy deposition which occur in proportional counters even if the counting gas and the counter walls have the same atomic composition. The distortions are due to the density difference between walls and counting gas. They consist in the simultaneity of particle passages which in the case of uniform density would occur separately. For heavy particles the delta-ray effect is dominant, but the V-effect can be significant at very high energies of the primary particles. In the case of x-rays, γ-rays, and fast electrons the distortions are due to the reentry, or backscattering, effect. Numerical estimates for the extent of the different processes and the corresponding change of mean event size and of event frequency are given.