Measurement of the ionization loss in the region of relativistic rise for noble and molecular gases

Abstract

The ionization loss of relativistic charged particles has been measured in thin samples of Ar, Xe, and propane in a pressurized gas proportional counter. Although the total relativistic rise becomes smaller for increasing pressure, the reduced fluctuation of the ionization loss permits, in principle, a better particle separation. Propane is found, especially in the lower pressure range, to give better particle separation at the expense of restriction to smaller momenta in comparison to Ar and Xe. An attempt is made to describe the relativistic rise and particle identification by simple gas parameters using Sternheimer's approximation.