Abstract
The gas gain and energy resolution of single and double THGEM detectors (5 cm × 5 cm effective area) with mini-rims (rim less than 10 μ m) were studied. The maximum gain was found to reach 5 × 103 and 2 × 105 for single and double THGEMs respectively, while the energy resolution for 5.9 keV X-rays varied from 18% to 28% for both single and double THGEM detectors of different hole sizes and thicknesses. Different combinations were also investigated of noble gases (argon, neon) mixed with a quantity of other gases (isobutane, methane) at atmospheric pressure.