The implications of particle energy and acidic media on gross alpha and gross beta determination using liquid scintillation

The interaction of humans with radioactivity present in the environment from natural and artificial sources necessitates an evaluation of its risk on human health. Gross alpha and gross beta activities can provide a rapid evaluation of the radioactive content of a sample and can be simultaneously determined by using liquid scintillation counters. However, calibration of the liquid scintillation counter is required and is affected by many factors, such as particle energy and the acidity of the media. This study investigates what effect the particle energy used for calibration has on misclassification and how to account for this misclassification in routine measurements.The variability in measurement produced by the final pH, as well as any acids used in sample treatment, was also studied. These results showed that the most commonly used acid for these types of analyses, HNO3, produced a high amount of misclassifications at very low pH. The results improved when HCl was used to adjust the sample to low pH.

► We study the effect of alpha and beta energies on PSA optimisation.
► The optimum PSA shifts to higher values as the alpha energy increases. Beta energies do not affect it.
► We study the effect of pH on the simultaneous determination of gross alpha/beta activities.
► HNO3 produces a high amount of misclassification at very low pH.
► The results improve when HCl is used to adjust the sample to low pH.