ABSTRACT

In order to obtain good energy resolution and good time or pulse-shape resolution in alpha spectra from liquid-scintillation pulses, all factors involved in producing the light pulses (scintillations) and converting them to electrical pulses must operate in an optimum and consistent manner. Energy transfer to a molecule that emits light (fluor) can be either directly from the excited molecule or indirectly through other molecules. The light-output/particle-energy relationship is different for the different radiation types, although beta- and gamma-produced pulses are similar and quite different from alpha-produced light pulses. All of the alpha decays that occur in the scintillator are detected. However, some of the alpha decays that occur within 50 μm of the sample vessel wall and go toward the wall will deposit some or all of their energy in the glass. In alpha-liquid-scintillation counting and spectrometry, quenching does not necessarily have the same effect or meaning as in beta-liquid-scintillation counting.