The Gigatracker: An ultra-fast and low-mass silicon pixel detector for the NA62 experiment

The Gigatracker is a hybrid silicon pixel detector developed to track the highly intense NA62 hadron beam with a time resolution of 150ps(rms). The beam spectrometer of the experiment is composed of three Gigatracker stations installed in vacuum in order to precisely measure momentum, time and direction of every traversing particle. Precise tracking demands a very low mass of the detector assembly (< 0.5% X0 per station) in order to limit multiple scattering and beam hadronic interactions. The high rate and especially the high timing precision requirements are very demanding: two R&D options are ongoing and the corresponding prototype read-out chips have been recently designed and produced in 0.13 mm CMOS technology. One solution makes use of a constant fraction discriminator and on-pixel analogue-based time-to-digital-converter (TDC); the other comprises a delay-locked loop based TDC placed at the end of each pixel column and a time-over-threshold discriminator with time-walk correction technique. The current status of the R&D program is overviewed and results from the prototype read-out chips test are presented

Heavy neutrino searches and NA62 status

The NA62 experiment at CERN SPS recorded in 2007 a large sample of $K^+\to\mu^+\nu_\mu$ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on $\mathcal{B}(K^+\to\mu^+\nu_h)$ and on the mixing matrix element $|U_{\mu4}|^2$ are reported. The upgraded NA62 experiment started data taking in 2015, with the aim of measuring the branching fraction of the $K+\to\pi^+\nu\bar{\nu}$ decay. An update on the status of the experiment is presented.The NA62 experiment at CERN SPS recorded in 2007 a large sample of $K^+ \to \mu^+ \nu_{\mu}$ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on $\mathcal{B}(K^+ \to \mu^+ \nu_h)$ and on the mixing matrix element $\lvert U_{\mu 4} \rvert ^2$ are reported. The upgraded NA62 experiment started data taking in 2015, with the aim of measuring the branching fraction of the $K^+ \to \pi^+ \nu \bar{\nu}$ decay. An update on the status of the experiment is presented