Investigation on the performance of a thick ceramic gas electron multiplier

We report the performance of a THick Gas Electron Multiplier (THGEM) fabricated by drilling holes in a gold-clad ceramic substrate using the standard PCB (Printed Circuit Board) technology and etching rims. The THGEM has a total thickness of 200 mu m with a hole diameter and rim size of 200 mu m and 80 mu m, respectively. In order to carry out a performance study, a detector was assembled by putting the THGEM inside a versatile chamber and irradiating it with a Fe-55 X-ray source (5.9 keV). An Ar/CO2 gas mixture was flushed inside the chamber at a pressure of about 1 atm, with volume ratios varying between 70/30 and 90/10. Pulse height spectra of the detector were recorded by a multichannel analyzer to investigate the gain and energy resolution at different drift and induction electric fields. The variations in the gain and energy resolution were also interpreted using simulations. The gain and resolution data of the THGEM were compared with those of a standard GEM which was measured using the same experimental setup.