The Gigatracker detector of the NA62 experiment at CERN SPS

The NA62 experiment at the CERN SPS is a fixed target experiment designed to measure the branching ratio of the ultra-rare Kaon decay K + → π + ν ν . The experiment uses an high-momentum K + decay in-flight technique to increase the rejection power of the main background: K + → π + π 0 . The Gigatracker is a hybrid silicon pixel detector, exposed to a 750 MHz high-energy charged hadron beam, built to give an accurate measurement of K + momentum and direction together with an high precision measurement of the beam particle arrival time (115 ps RMS resolution per plane). It comprises three stations placed right before the K + decay region and inserted around two achromats. The detector works in vacuum ( ∼ 1 0 − 6 mbar ) at about − 10 ° C . Each station is made of a 200 μ m thick silicon sensor readout by 10 TDCPix, custom 100 μ m thick ASICs, and cooled by an innovative double circuit silicon micro-channel cooling system. All these parts are designed to minimize the total material budget which, in the final detector, amounts to less than 1.5% X 0 for the three stations. In order to sustain the high rate of incoming particles, each TDCPix, operating in a self triggered mode, is equipped with four 3.2 Gb/s serializers sending data to the detector DAQ system based on a read-out card per TDCPix chip sending trigger-matched hits to 6 PC servers. I will describe the whole detector and present some of the results from data collected during the 2016 NA62 runs.