CERN - European Organization for Nuclear Research - Physics Department - NA62

The aim of NA62 (Kaon Factory)

NA62 initially proposed to measure the very rare kaon decay K+-> pi+ nu nubar at the CERN SPS to extract a 10% measurement of the CKM parameter |Vtd|.
The experiment aims to collect about 80 K+-> pi+ nu nubar events at the SM prediction with a signal to background ratio of 10:1 in two years of data taking.

We are using 400 GeV/c protons from the SPS to perform the experiment.
There are several challenging aspects for this experiment. They include:

  • Performing tracking at 1~GHz total rate, 40 MHz/cm2, within a minimal material budget, minimal detector dead-time, and excellent time resolution ( 150 ps).
  • Achieving positive kaon identification in a high rate environment by means of a differential Cherenkov counter insensitive to pions and protons with minimal accidental mistagging.
  • Constructing and operating hermetic photon vetoes to provide a pi0 rejection of 108.
  • Achieving a muon rejection of at least 105 using a magnetised iron/scintillator detector.
  • Achieve a two or more standard deviations pi/mu separation up to 35 GeV/c momentum by means of a RICH counter.
  • Performing redundant measurement of the momentum of the incoming K+ and outgoing pi+ for suppression of the tails in the reconstruction of the missing mass for two body decays.
  • Vetoing the charged particles coming from three and four body kaon decays.
  • Minimizing the accidental activity from non-kaon decays (e.g. muons from the proton dump and tracks coming from pion and kaon decays occurring upstream of the decay region).