Proportional counters are summarized below.
Proportional Counters Summary
When radiation enters a proportional counter, the detector gas, at the point of
incident radiation, becomes ionized.
The detector voltage is set so that the electrons cause secondary ionizations as
they accelerate toward the electrode.
The electrons produced from the secondary ionizations cause additional
This multiplication of electrons is called gas amplification.
Varying the detector voltage within the proportional region increases or decreases
the gas amplification factor.
A quenching gas is added to give up electrons to the chamber gas so that
inaccuracies are NOT introduced due to ionizations caused by the positive ion.