A multiwire ionisation chamber filled with liquid xenon as a position sensi
tive detector for Positron Emission Tomography is studied. Both xenon scint
illation, which provides a fast trigger, and ionisation charge for position
and energy measurements are read. The detection efficiency of the detector
is assessed in separate measurements of the probability of detection of th
e scintillation light and the charge signals due to 511 keV gamma-rays. The
se were measured to be about 1 and 0.82, respectively.