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 neutrinos created by a particle collider, promising to deepen our understanding of these particleswhich are the most abundant ones in the universe. Neutrinos interact 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 been
 of low energy. However, the neutrinos detected by FASER are likely the most energetic ever produced in a laboratory. They have similar energies to the neutrinos found when cosmic rays produce cascades of particles as they interact with our atmosphere.

"This study could 
shed light on cosmic neutrinos that travel large distances 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 University of Geneva (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
, with major 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 of the read-out and trigger electronics and software. Members of the DPNC were part of the teams that installed, commissioned and currently operate the experiment. 

FASER is a unique and very recent particle detector
. Data collection started in 2022 and its first results were announced at a conference on 19 March 2023. Compared 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. It took only a few years to design and construct, using spare parts from other experiments. 

Beyond neutrino physics, one of FASER's main goals is to help identify the particles that make up dark matter, which has never been directly observed so far and which is thought to comprise most of the matter in the universe. 

"Over the next few years, FASER is expected to obtain 10 times more data from the LHC," says Lorenzo Paolozzi, professor at DPNC and 
staff at CERN, whose group contributes significantly to the technical improvement of FASER, to optimise its sensitivity so that the collaboration can more efficiently search for new physics.

March 19, 2023