Scintillation of liquid xenon and its application to nuclear radiation detectors

We review the scintillation mechanism of liquid rare gases and estimate the absolute scintillation yield of liquid xenon in order to understand the superiority of liquid xenon as a detector medium. The decays of scintillation light from liquid xenon, which are faster than those of scintillation light from crystal scintillators, are summarized. New photomultipliers with high quantum efficiency that can operate at liquid xenon temperature were recently developed by Hamamatsu Photonics Co. Using these photomultipliers, a new gamma-ray calorimeter system, whose sensitive volume is surrounded by many photomultipliers was proposed. This new calorimeter system was applied to a mu⁺rarre⁺gamma decay search experiment and then to liquid xenon scintillation time-of-flight positron-emission-tomography (TOF-PET). A third application, a new apparatus for detecting solar neutrinos and for use in the dark matter search experiment developed at Kamioka, Japan, is also presented