The pulse height can be computed if the capacitance, detector characteristics, and radiation are
known. The capacitance is normally about 10-4 farads. The number of ionizing events may be
calculated if the detector size and specific ionization, or range of the charged particle, are known.
The only variable is the gas amplification factor that is dependent on applied voltage.
The operation of gas-filled detectors is summarized below.
Gas-Filled Detectors Summary
The central electrode, or anode, attracts and collects the electron of the
The chamber walls attract and collect the positive ion.
When the applied voltage is high enough, the ion pairs initially formed
accelerate to a high enough velocity to cause secondary ionizations. The
resultant ions cause further ionizations. This multiplication of electrons
is called gas amplification.