NA62 experiment

NA62 experiment
Name	NA62
Location	CERN, Prevessin
Institution	CERN
Established	2007

NA62 experiment The NA62 experiment is a fixed-target particle physics experiment at the CERN Super Proton Synchrotron, designed to study rare decays of charged kaons. It builds on the legacy of experiments such as NA48 and interfaces with accelerator complexes like the Proton Synchrotron and the Large Hadron Collider program. The collaboration involves institutions from across Europe and beyond, including national laboratories such as INFN, CNRS, and DESY.

Overview

NA62 operates on a high-intensity 400 GeV/c secondary beam delivered by the Super Proton Synchrotron to a 75 GeV/c charged hadron beamline produced by the CERN North Area facilities. The experiment's apparatus is installed in the ECN3 cavern in the Prevessin site, adjacent to infrastructures used by experiments like NA48/2 and COMPASS. The project was proposed and approved within the European Organization for Nuclear Research framework and receives technical and scientific support from national funding agencies including STFC, DFG, and SNSF.

Experimental goals and physics program

NA62 targets ultra-rare processes predicted by the Standard Model such as the decay K+ → π+νν̄ with extremely small branching ratio, testing flavor-changing neutral current processes originally analyzed in the context of the Glashow–Iliopoulos–Maiani mechanism and loop diagrams related to the Cabibbo–Kobayashi–Maskawa matrix. Measurements constrain models beyond the Standard Model including scenarios with supersymmetry, leptoquarks, extra dimensions, and heavy neutral leptons motivated by the seesaw mechanism and neutrino oscillation anomalies. NA62 also searches for dark-sector candidates like axion-like particles, hidden photons studied in contexts such as the DarkLight proposal, and tests of discrete symmetries connected to the CPT theorem and CP violation research pioneered in kaon physics by experiments like NA31 and KTeV.

Detector and beamline

The beamline architecture includes a production target and a system of magnetic optics similar to those used in experiments such as NA48, with a differential Cherenkov counter (KTAG) derived from designs like the CEDAR Cherenkov detectors. Key subdetectors include a precision silicon pixel tracker inspired by developments at CERN's Velo and ALICE inner trackers, a magnetic spectrometer with straw chambers evolved from COMPASS technology, a ring-imaging Cherenkov detector (RICH) building on concepts used in LHCb, and electromagnetic calorimetry borrowing techniques from NA48's liquid-krypton calorimeter. Muon veto systems take cues from designs at MINOS and OPERA, while photon vetoes cover large solid angles informed by KOTO and E949 experiments. The entire detector chain is mounted along the CERN North Area beam axis and interfaces with accelerator diagnostics used by the SPS operations team.

Data acquisition and trigger systems

NA62 employs a multi-level trigger and data-acquisition (DAQ) architecture comparable to systems used by ATLAS and CMS for high-rate environments. A hardware Level-0 trigger reduces the 750 MHz beam-rate background using fast signals from calorimeters and the RICH, followed by software High-Level Trigger stages running on commodity computing farms similar to those developed by the WLCG community. Time-stamping and synchronization use clock distribution methods akin to the White Rabbit protocol applied in other CERN experiments. Event-building and storage interface with tape and disk infrastructures coordinated through national grids such as CERN Open Data Portal partners and regional centers like INFN CNAF.

Analysis methods and key results

Analyses rely on blind-analysis methodologies pioneered in precision experiments including E787 and E949, with background estimation techniques using control samples from decays like K+ → μ+ν and K+ → π+π0. Kinematic reconstruction exploits missing-mass squared variables and particle-identification likelihoods combining RICH, calorimeter, and muon detector information, analogous to strategies used in LHCb rare-decay searches. Key published results set world-leading limits and measurements on the branching ratio of K+ → π+νν̄, searches for heavy neutral leptons similar to those targeted by PS191, and bounds on dark-photon couplings comparable to limits from BaBar and NA64. Results have been presented at forums such as the International Conference on High Energy Physics and the Rencontres de Moriond series.

Collaborations and organization

The NA62 collaboration comprises universities and laboratories from countries including Italy, United Kingdom, France, Switzerland, Spain, Germany, and Russia, organized under a spokesperson and an institutional board in a structure resembling governance models at CERN experiments like CMS and ATLAS. Technical coordination involves detector groups with links to institutes such as INFN Sezione di Pisa, University College London, CNRS/IN2P3, and MPI für Kernphysik. Funding and oversight engage agencies like European Research Council grant holders, national research councils including STFC and DFG, and collaborative agreements with accelerator operations at CERN.

Category:Particle physics experiments