NA62 experiment

The NA62 experiment (known as P-326 at the stage of proposal) is a particle physics experiment in the North Area of the SPS accelerator at CERN. The experiment was approved in February 2007. Data taking began in 2015, and the experiment is expected to become the first in the world to probe the decays of the charged kaon with probabilities down to 10⁻¹². The experiment's spokesperson is Augusto Ceccucci. The collaboration involves 333 individuals from 30 institutions and 13 countries around the world.

The experiment is designed to conduct precision tests of the Standard Model by studying rare decays of charged kaons. The principal goal, for which the design has been optimized, is the measurement of the rate of the ultra-rare decay K⁺ → π⁺ + ν + ν with a precision of 10%, by detecting about 100 decay candidates with a low background in two years of data taking. This will lead to the determination of the CKM matrix element |V_td| with a precision better than 10%. This element relates very accurately the likelihood that top quarks decay to down quarks. The Particle Data Group's 2008 Review of Particle Physics lists |V_td| = 6997874000000000000♠0.00874+0.00026
−0.00037.

In order to achieve the desired precision, the NA62 experiment requires a certain level of background rejection with respect to signal strength. Namely, high-resolution timing (to support a high-rate environment), kinematic rejection (involving the cutting on the square of the missing mass of the observed particles in the decay with respect to the incident kaon vector), particle identification, hermetic vetoing of photons out to large angles and of muons within the acceptance, and redundancy of information.

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