AV¶ÌÊÓƵ

The FASER experiment at the CERN LHC detects for the first time neutrinos produced at a particle collider

The FASER collaboration has detected for the first time neutrinosÌýcreatedÌýby a particle collider, promising to deepen our understanding ofÌýthese particles,Ìýwhich areÌýthe most abundantÌýonesÌýin the universe. NeutrinosÌýinteract extremely weakly with matter and play a fundamental role in the nuclear processes within stars.

Since their discovery in 1956, the majority of neutrinos studied by physicists have beenÌýofÌýlowÌýenergy. However, the neutrinos detected by FASER areÌýlikelyÌýthe most energetic ever produced inÌýaÌýlaboratory. TheyÌýhaveÌýsimilarÌýenergiesÌýto the neutrinos found when cosmic rays produce cascades of particles as they interact with our atmosphere.

"This study couldÌýshed light onÌýcosmic neutrinos that travelÌýlargeÌýdistances and collide with the Earth providing a window into the most distant parts of the universe," says Anna Sfyrla, professor in the Department of Nuclear and Corpuscular Physics (DPNC) at the AV¶ÌÊÓƵ (UNIGE) and member of the FASER collaboration.

This is one of the first and most recent results from FASER (Forward Search Experiment) using data from collisions at the Large Hadron Collider (LHC) at CERN. FASER is a particle detector designed and built by an international consortium of physicists, withÌýmajor contributions from the DPNC. The research groups of Professors Giuseppe Iacobucci and Anna Sfyrla, as well as the technical teams of the department, were significantly involved in the construction of the part of the detector that measures the properties of charged particles. They also led the development and implementation ofÌýthe read-out and trigger electronics and software. Members of the DPNC were part of the teams that installed, commissioned andÌýcurrentlyÌýoperate the experiment.Ìý

FASER is a unique and very recent particle detector. Data collection started in 2022 and its first results were announced at a conference onÌý19ÌýMarch 2023.ÌýCompared to other CERN detectors, such as ATLAS, which is more than 20 metres high and weighs 7,000 tonnes, FASER weighs just one ton and fits perfectly into a small side-tunnel of the LHC.ÌýIt took only a few years toÌýdesign and construct,ÌýusingÌýspare parts from other experiments.Ìý

BeyondÌýneutrino physics, one of FASER's main goals is to help identify the particles thatÌýmake upÌýdark matter, which has never been directly observedÌýso farÌýandÌýwhichÌýis thought toÌýcompriseÌýmost of the matter in the universe.Ìý

"Over the next few years, FASER is expected to obtain 10 times more data from the LHC," says Lorenzo Paolozzi, professor at DPNC andÌýstaff atÌýCERN, whose group contributesÌýsignificantly to the technical improvement of FASER, to optimise its sensitivity so that the collaboration canÌýmore efficientlyÌýsearch for new physics.