Liquid-helium scintillation detection with germanium photodiodes

Special high purity germanium photodiodes were developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV (-) particles are presented. It is suggested that the use of these photodiodes as liquid helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes.