Some Factors Affecting Alpha Particle Detection In Liquid Scintillation Spectrometry

Pulse shape analyzers have been introduced in commercial liquid scintillation counters, such as the WaIlac 1220 QuantulusTM and 1219 SM, enabling separation of alpha particle spectra from other types of radiation in a single measurement and making ultra sensitive alpha counting possible. Background count rates as low as one count per day for 214Po in a teflon vial are achievable while still retaining nearly 100% counting efficiency. The number of photons per decay event however, is relatively low in liquid scintillation counting, leading to energy resolution of the order of 10%. Energy resolution has been found to improve with low water to cocktail ratios and opaque vial types. Easy and fast sample preparation together with the ultra low background make liquid scintillation spectrometry a competitive method in environmental counting of alpha particles.