Operational experience with the NA62 Gigatracker

Abstract

The Gigatracker is a hybrid silicon pixel detector developed for the NA62 experiment at CERN, which aims at measuring the branching fraction of the ultra-rare kaon decay K+ → π+ vv at the CERN SPS. The detector has to track particles in a 75 GeV/c hadron beam with a flux reaching 1.3 MHz/mm2 and provide single-hit timing with better than 200 ps r.m.s. resolution for a total material budget of less than 0.5% X0 per station. The tracker comprises three 61 × 27 mm2 stations installed in vacuum (about 10-6 mbar) and cooled with liquid C6F14 circulating through micro-channels etched inside few hundred of microns thick silicon plates. Each station is composed of a 200 μm thick planar silicon sensor bump-bonded to 2 × 5 custom 100 μm thick ASIC, called TDCpix. Each chip contains 40 × 45 asynchronous pixels, each 300 × 300 μm2 and is instrumented with 720 time-to-digital converter channels with 100 ps bin. In order to cope with the high rate, the TDCpix is equipped with four 3.2 Gb/s serializers sending out the data. Detector description, operational experience and results from the NA62 experimental runs will be presented.