Speaker
Description
The GigaTracKer is a hybrid silicon pixel detector of the fixed-target experiment NA62 at the CERN SPS that aims to precisely measure the branching ratio of the very rare $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay. The detector was designed to provide measurements of the momentum, direction, and time of beam particles arriving at a rate of 750 MHz. The tracking system consists of four stations installed in vacuum ($\sim10^{-6}$ mbar), $60.8 \times 27\ \text{mm}^2$ each, with a total material budget of less than $2\%$ X$_0$. Each station is cooled with a microchannel cooling plate used for the first time in a high-energy physics experiment. The beam particles are tracked in four dimensions using time-stamping pixels ($300\times300\ \mu \text{m}^{2}$) with a single-hit time resolution of 115 ps. This performance must be maintained despite the beam irradiation that amounts to $4.5 \times 10^{14}$ 1 MeV neutron equivalent yearly fluence (integrated over a data taking period of 200 days). The detector has been fully operational since 2016. We describe the GigaTracKer design, performance, and developed 4D track reconstruction algorithms.