Numerical counting ratemeter with large time constant for very low count rates - operational results

The use of an analogue ictometer poses technical problems for measuring low count rates. These latter call for time constants of up to 1000 sec. The numerical technique is better adapted and makes it possible to increase the time constant to 1000 sec. or over. The equipment described consists of 6 numerical ictometers fitted in a 3 U 3 drawer. By means of a clock it is possible to vary the counting time from 1 second to 1000 seconds, using values at 5, 10, 50, 100 and 500 seconds. The corresponding values of the frequency are 500 c/sec, 100, 50 10. 5. 1 and 0.5 c/sec with a resolving power of 0.2 per cent. The result appears on an indicator panel (galvanometer) and is available in the form of an analogue voltage suitable for a 50 mV MECI recorder. (author)