Scintillation Detectors Using Large Area Silicon Avalanche Photodiodes

Low noise, large area silicon avalanche photodiodes have now been made to replace photomultiplier tubes in certain scintillator detector applications in which overall size and ruggedness are important. Previous devices have been limited by poor optical sensitivity and very small active size. These sensors when coupled to a 1-inch NaI(T1) crystal have produced pulse height spectra with resolution for Cs 137 gamma radiation as low as 9.5% FWHM. This achievement is the result of improvements in both silicon material quality and device design. Based on these results the future prospects of such detectors are very encouraging.