DEVELOPMENT OF A FUNDAMENTAL SCALING RULE FOR NUCLEAR COUNTING EXPERIMENTS*

A fundamental scaling rule for the optimization of available time between counting time spent on background measurements and counting time spent on item measurements has been developed. In field situations in particular, only minimal thought is typically given to the time allotted for background and item measurements when conducting counting experiments on radiological material. Arbitrarily determined counting times are often used, resulting in half the available time devoted to the background measurement and half to the item. However, a given counting time can be optimally partitioned between background and item measurements to maximize precision. For simple Poisson counting experiments, we have determined the theoretical optimum fraction of time spent counting the item with respect to the signal-to-background ratio. The target measurement precision is also considered with the counting time partition to determine the time required to achieve desired results. The resulting scaling rule can be utilized as an experimental planning tool to ensure the most efficient use of available counting time. The guidance provided, along with the equations and graphs presented, can be applied in a straightforward manner, even in field situations where many other constraints and operational pressures are present.