A Differential Counting Rate Meter for Low Counting Rates

A counting rate meter was constructed after a circuit suggested by Harald Trefall, with a power supply after Elmore.The instrument was tested and proved quite stable after operating for several weeks.The response of the instrument was calculated and the experimental results verified the calculations.Methods of calibration and operation of the instrument were developed to obtain the full benefit of its design.A set of calibration curves was obtained from the counting rate meter and a suggestion for their use in interpreting the output was made. The research resulted in the construction of an instrument with the following specifications: Maximum Counting Rates: 100, 200, 300 cpm. Sensitivity of indicating stage: 30, 50, 100% of maximum counting rate for full scale deflection. Time constants: Charging 2760 ± 300 seconds Discharging 4680 ± 300 seconds Probable Error: 0.3-1.2%, depending upon rate. Overall Resolving Time: 290 microseconds. Univibrator Deadtime: 220 microseconds. Advisor: Robert L. Chasso