Abstract:

The Gas Electron Multiplier consists of a metal-clad polymer foil, chemically pierced by a high density of holes; it permits to multiply electrons released in the gas, transferring the amplified charge to a following device. I will describe recent studies aimed at understanding and optimizing the structure, and in particular the performance at high rates and under exposure to heavily ionizing tracks. GEM-based detectors have been adopted by several experiments (HERA-B, LHC-B, COMPASS), and are being considered by others. The development and performance of a large size prototype (32x32 cm2) with two-dimensional readout will be described. The photon and ion feedback suppression properties of GEM can be exploited for other applications, namely for high-resolution end-cap readout of Time Projection Chambers, and single photoelectron detection in gaseous photomultipliers; developments in these fields will be discussed.