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The GigaTracker magnetic spectrometer (GTK) has been designed for the NA62 experiment at the CERN SPS. NA62 aims to measure the branching fraction of the ultra-rare decay K+ → π+ vm[1] [2]. The detector is made of three planes of hybrid pixels, as shown in Figure 1. It has to track particles in a beam with a flux reaching 1.3 MHz/mm2 and provide single-hit timing with 200 ps resolution for a total material budget of less than 0.5% X 0 per station. In order to maintain good timing performance, it is planned to replace the detectors after 100 days of operation, which would correspond to a fluence of 1014 1 MeV eq. n/cm2.

We present the results of a study of the feasibility of implementing real-time track reconstruction within the framework of a pre-existing readout system, using the “Artificial Retina” approach. This is the first attempt at building a complete medium-size prototype of this kind (comprising about 8M Logic Elements, distributed on several separate boards), operating it continuously at its limit speed. This study emphasizes logic architecture, correct operation, size, and compatibility with a standard readout framework, to explore its useability as an add-on to a conventional readout system. For this reason we have chosen for implementation a moderate-cost, moderate-speed board already in use in the data acquisition of an existing HEP experiment. Our choice fell on the readout boards currently in use by the NA62 experiment (TEL62), each equipped with 5 Altera Stratix III FPGAs and 4 Gbit/s ethernet interface. We have reprogrammed the board firmware in two different ways, to make the boards behave as the two main blocks of a AR system (switch system, and cellular processor farm). They are interfaced via the front panel, inverting their normal data flow path, by custom interconnection boards, and devoped in internal sytem for continuous feeding of data in order to test them at their maximum achievable speed. We report the results of extensive tests perfomed with this prototype, and discuss their implications regarding the applicability of the “retina architecture” to faster, and custom-developed real-time processors.

The main goal of the last generation kaon experiment NA62 at CERN is the measurement of the branching ratio of the ultra-rare decay K+ → π+ vv with 10% uncertainty. One of the key principles of the experiment is the reliable particle identification (PID) which is crucial for the rejection of background decay modes with muons and electrons in the final state, e.g. K+ → μ+ v μ . The RICH detector is designed to suppress muon contamination in the pion sample by the factor of 100 in the momentum range between 15 and 35 GeV/c, to measure the pion crossing time with a resolution of about 100 ps and to produce a trigger signal for a charged track. The detector was installed in 2014 and has been operating during NA62 data taking periods: a pilot run in 2014, the Commissioning Run in 2015 and Physics Run in 2016. This paper describes the RICH construction and measurements of the detector performance.