A counting system for use with gas flow proportional counters has been examined and the advantages are discussed of a specially developed pre-amplifier of current to voltage conversion type. The system proposed, embodying a conventional voltage amplifier as main amplifier, retains the advantages of the current mode signals from a flow counter. The present method has the further convenience of using a commonly adopted general purpose voltage amplifier with pole/zero cancellation, a base-line restorer, and other nuclear instrument modules (NIM).
Good plateau characteristics were obtained for both α- and β-particles from RaDEF source with double and triple differentiation pulse shaping. Furthermore a slope of less than 0.1%/100V was obtained with 32P source at a counting rate of 2, 000cps. A noise level of 0.03μA peak-to-peak was realized without particular selection of transistors permitting detection of 2-3 ion pairs of ionization.
