Development of a Liquid Xenon Photon Detector

—Toward the Search for a Muon Rare Decay Mode at Paul Scherrer Institute—

Abstract

We are developing a new type of photon detector in preparation of an experiment to search for muons decaying into positrons and gamma rays. In the experiment, the photon detector will utilize liquid xenon (Xe) as the scintillation material because of its fast response, large light yield, and high density. The scintillation light emitted in liquid Xe will be observed directly by positioning photomultipliers (PMTs) in the liquid without the use of a transmission window. In order to determine proper experimental procedures and study the detector response to gamma rays, we constructed a prototype utilizing a 100-liter volume of liquid Xe. Current status and future prospects of detector development are reported in this article.