Cerenkov counting as a complement to liquid scintillation counting

A commercially available spectrometer was calibrated for liquid scintillatoion (LS) and Cerenkov counting efficiency (CCE) using National Institute of Standards and Technology traceable solutions. The CCE increased linearly over a 3 order of magnitude range in 40K β activity, and by 42% per MeV as β-energies increased from 0.300 to 3.54 MeV, achieving a maximum value of 80% for 106Ru/106Rh. The CCE can be enhanced by 10–15% when a wavelength shifter is used. A comparison of the data showed that the CCE was typically 20–50% less than the LS counting efficiency for β-particles with maximum energies >1 MeV. Applications that utilize sequential CCE and LS counting to quantitate activity concentrations are discussed for samples containing two β-emitting nuclides of differing energies.