Applied Voltage:

The relationship among the applied voltage and pulse height in a detector is extremely complex. The Pulse height and the number of ion pairs collected are directly associated. Figure describes ion pairs collected -vs- applied voltage. Two curves are displays:  one curve for alpha particles and one curve for beta particles; each curve is separated into various voltage regions. A alpha curve is higher than the beta curve from Region I to categories of Region IV due to the larger number of ion pairs produced through the initial reaction of the incident radiation. An alpha particle will established more ion pairs than a beta since the alpha has a much greater mass. The difference in mass is negated at once the detector voltage is increased to Region IV because the detector fully discharges along with each initiating event.

Figure: Ion Pairs Collected -vs- Applied Voltage