A New Look at the PPAC

摘要

The Parallel Plate Avalanche Counter (PPAC) has been used mostly for measuring the energy loss of single, heavily ionizing particles. A PPAC is even more effective with high-energy showers for which a single event causes hundreds of electrons to pass through it. For operation at reduced pressures, the alkanes such as iso-butane, C_4H_(10) are excellent PPAC gasses with the quality of performance increasing with the size of the molecule. Under some circumstances the perfluoroalkanes such as perfluoropropane, C_3F_8, may be preferred. For operation at atmospheric pressure, CF_4 and mixtures containing Ar and CO_2 work well.