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$^{+} \rightarrow \pi^{+} \nu \overline{\nu}$ at the CERN SPS. The detector has to track particles in a 75~GeV/c hadron beam with a flux reaching 1.3~MHz/mm$^2$ and provide single-hit timing with better than 200 ps r.m.s. resolution for a total material budget of less than 0.5\%~X$_0$ per station. The tracker comprises three 61$\times$27~mm$^2$ stations installed in vacuum (about 10$^{-6}$~mbar) and cooled with liquid C$_{6}$F$_{14}$ circulating through micro-channels etched inside few hundred of microns thick silicon plates. Each station is composed of a 200~$\mu$m thick planar silicon sensor bump-bonded to 2$\times$5 custom 100~$\mu$m thick ASIC, called TDCpix. Each chip contains 40$\times$45 asynchronous pixels, each 300$\times$300~$\mu$m$^2$ 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.