High pressure gas scintillation drift chamber with photomultipliers inside of working medium

The first results of testing a high pressure gas scintillation drift chamber as with single photomultiplier and with matrix of 7 photomultipliers placed inside of pressurized xenon are presented. Two types of ordinary glass tube photo-multipliers that are found mechanically stable up to 8 and 45 bar of external pressure have been used. The quantum efficiency of vacuum deposited on glass PMT window p-terphenyl is about 90% at 170 nm. For 60 keV ²⁴¹Am γ-source energy resolution of 4% FWHM, intrinsic spatial resolution of 0.2 mm FWHM along the drift direction and 1.2 mm FWHM in the perpendicular plane are achieved at 20 bar xenon filling