Photon detection related to scintillation process for alpha emitter analysis in the environment

High sensitive detector and high resolution are required when analysing alpha emitters in environmental samples by liquid scintillation spectrometry, in order to avoid merging peaks between several radionuclides. The performances of a very sensitive detector, namely the avalanche photodiodes (APD) are presented and compared to that of photomultiplier tubes (PMT). Enhancement of the resolution up to 50 % is observed. The performances of a liquid scintillation spectrometer equipped with APD can be still increased due to its capability to match easily any scintillator with the large spectral response of the APD. Moreover, the geometry of light collection is not fully optimized and improvement is expected. (authors)