Editing Proportional counter (section)

===Spectroscopy===
The proportionality between the energy of the charged particle traveling through the chamber and the total charge created makes proportional counters useful for charged particle [[spectroscopy]]. By measuring the total charge (time [[integral]] of the [[electric current]]) between the electrodes, we can determine the particle's [[kinetic energy]] because the number of ion pairs created by the incident ionizing charged particle is proportional to its energy. The energy resolution of a proportional counter, however, is limited because both the initial ionization event and the subsequent 'multiplication' event are subject to statistical fluctuations characterized by a standard deviation equal to the square root of the average number formed. However, in practice these are not as great as would be predicted due to the effect of the empirical [[Fano factor]] which reduces these fluctuations.<ref name = knoll /> In the case of argon, this is experimentally about 0.2.