Detection of X-Rays with a Proportional Counter

Gas-filled chambers operating in the proportional counter range are used in certain special applications for the detection of X-rays with energy less than 100 

X-ray proportional counters are usually cylindrical with a very thin beryllium window located either on the side or at the front end. They use a gas that is a mixture of a noble gas—He, Ne, Ar, Kr, Xe—with methane, at a pressure of about 1 atm. 

The energy resolution of these counters is such that the FWHM is 1-2 keV at 20 keV. Thus, proportional counters are superior to scintillation counters in this energy range. 

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