Optimization of evaporation and counting times for measurements of short-lived gamma-ray emitters in water samples

A methodology how to optimize the throughput of a laboratory when the sample preparation and sample measurement times are related is presented for the case when radioactive decay during the processing time cannot be neglected. It is assumed that the sensitivity of the measurements is prescribed and can be attained by processing a larger sample quantity or by extending the measuring time. The methodology is illustrated for measurements of 131I in samples of the dry residue obtained by evaporation of water. It is demonstrated that the quantities which determine the throughput of the laboratory are the maximum sample size which can be processed, the evaporation rate and the quality of the spectrometers.