In this study, we have investigated a 2-dimensional gas
detector based on plasma display technology as a candidate for the
flat-panel radiation detector. Using the Geant4 and Garfield codes,
that simulate the passage of particles through matter, we examined
the dependence of X-ray absorption and multiplication factors on the
Xe-He gas mixture. Prototype detectors, with four different gas
mixtures, were designed and fabricated based on the results from the
simulations. The performance of four detectors was evaluated by
measuring the collected charge density, dark current density and
sensitivity. The maximum collected charge occurred when the Xe
80%-He 20% gas mixture was 1.216 μC/cm2 at -1800
V. The dark current of this detector varied between 0.124 and 0.321
nA/cm2 in the bias range of -300 to -1800 V, which is
approximately one-third of the dark current density of an a-Se
based detector, in this range. The sensitivity of Xe 80%-He
20% detector was 0.246 nC/mRcm2 at 0.61 V/μm. It is
about a tenth lower than that of an a-Se based detector at 10
V/μm.