The GEM Technology for the SBS at Jefferson Lab

F. Noto[1], V. Bellini[1], E. Cisbani[2], and C. Sutera[1]
[1]INFN Sez. di catania, Università di Catania, Italy
[2]INFN Sez. Roma, Italy

The Gas Electron Multiplier (GEM) technology has proven to tolerate rate up to 50 MHz/cm2 without noticeable aging and to provide the required resolution on working chambers up to 33x33 cm2. The SBS GEM chambers have been designed in a modular way: each chamber consists of 3 adjacent GEM modules. Each GEM module has an active area of 40x50 cm2, which 2 represent the current standard double mask GEM technology limit. The design of the module using COMSOL has optimized the active area, surrounded by a tiny 8 mm width mechanical frame of Permaglas™ which embeds the protection resistors that distribute the high voltage to the GEM foils and includes the gas inlet-outlet pipes. In order to safely guarantee the required tracking performance, an additional 2D small plane of high resolution silicon detector is planned to be placed before the SBS dipole.