Construction and commissioning of the cylindrical-GEM inner tracker of KLOE-2

Abstract

The KLOE-2 experiment aims to continue the successful program of KLOE,that collected 2.5 fb−1 of integrated luminosity between 2001 and 2006 at DAΦNE, the ϕ-factory at the Frascati National Laboratories of INFN, fulfilling a vast set of precision kaon and hadron physics measurements.One of the major upgrades of the apparatus is the extension of the tracking system with the insertion of a central Inner Tracker (IT) inside the Drift Chamber. The IT is realized as four concentric cylindrical triple-GEM detectors, directly fixed onto the DAΦNE beam pipe, at a distance from the interaction point going from 13 cm to 20.5 cm.The conception, design and realization of the cylindrical-GEM have been taken on in Frascati since 2007, with the goal of minimizing dead-spaces, support frames and material budget. The final result is a very light detector with an overall thickness corresponding to only 2% of a radiation length.Moreover the detector exploits the outstanding rate capability typical of the micro-pattern gas detectors, useful to cope with the unavoidable background of a high-luminosity e+e− collider.The tracker provides space points with resolutions of 200 μm in rϕ and 500 μm in Z. The two coordinates are obtained by an XV strips patterned readout coupled to the GASTONE front-end, a 64 channels ASIC with digital output expressly developed for this experiment.