ABSTRACT
For example, the uncertainty of the analysis of a sample with a total activity of 1000 dpm (sample + background), counted for 10 min in a Geiger-Mueller counter with 10% efciency and a background of 40 cpm (also determined by a 10-min count), would be 73.3 dpm, or 12.2% of the net dpm at the 95% condence level. The same 1000 dpm sample counted for 10 min in a gas proportional counter with 40% efciency and a background of 1 cpm would have an uncertainty of 31.0 dpm, or 3.1%. Thus, the latter counting method will provide a more precise result. Increasing the counting time will also decrease the uncertainty of both measurements.
