TPC based on optically readout GEM.
Antochi C.V., Baracchini G., Cavoto G., De Stena A., Di Marco E., Marafini M., Mazzitelli G., Pinci D., Renga F., Tomassini S., Voena C.
Scintillation mechanisms in gases offer the possibility of an optical read out of GEM detectors. CMOS sensors provide a very high granularity along with a low noise level and a high quantum efficiency. An innovative concurrent readout by a photomultiplier system provides the time resolution necessary for the complete reconstruction of the position of the clusters. The performance of a triple-GEM TPC are presented. About 100 photons are collected per primary electron providing a space resolution of about 35 $\mu$m. The device showed high sensitivity to energy deposit: 6 photons are collected per released electronvolt.