A new glass GEM with a single-sided guard-ring structure

The gas electron multiplier (GEM) is a gaseous detector that is widely used in many applications. Our glass GEM (G-GEM) comprises a photo-etchable glass (PEG3, HOYA Corporation, Japan). Our research indicated that it shows superior performance compared with other gas detectors. In this article, a new type of G-GEM is introduced. It has a guard-ring structure around the holes in order to improve the spark tolerance by reducing the total capacitance of each hole structure. A measured gas gain of approximately 7500 is attained for this new G-GEM with a single-sided guard-ring structure using a gas mixture of Ar (90%) and CH4 (10%) in the gas flow mode. An energy resolution of 17.3% (FWHM) is also achieved with a collimated 6 keV X-ray beam. The results of a 10 to 12 hour gas gain stability measurements are also shown.