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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 μ m with a hole diameter and rim size of 200 μ m and 80 μ 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 55Fe X-ray source (5.9 keV). An Ar/CO 2 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. [ABSTRACT FROM AUTHOR]

The effective gain variations as a function of the drift electric field strength (E d) are measured in a ceramic thick gas electron multiplier (THGEM) and a standard GEM using the same experimental setup. Significant differences in the variations are observed between the THGEM and the standard GEM. The effective gain variations with E d are quantitatively reproduced by calculations via investigating the respective influence of E d change on the electron collection efficiency and the gain. The differences in the effective gain variation with E d between the THGEM and standard GEM are thus explained. • A method was suggested to calculate the electron collection efficiency of a fully charged THGEM. • The relative gain after increasing drift electric field was found independent on the starting positions of primary electrons. • The effective gain variation with drift electric field was interpreted. [ABSTRACT FROM AUTHOR]