For the first time, we might be able to detect neutrinos interacting with matter at the Large Hadron Collider with FASERv

Credit: FASER\CERN

Neutrinos are subatomic particles with very, weighing 50,000 times less than an electron, other than that they are very abundant in the universe, but very difficult to detect because their interaction with matter is very little, so little that trillions of neutrinos are passing through the Earth every second and the amount which interact with matter is very minuscule.

And at CERN, no neutrino that has ever been produced at the particle collider has ever been detected, so in order to detect them, CERN implemented a new detector for the FASER (ForwArd Search ExpeRiment) experiment (One of the experiments at LHC, designed to search for light and extremely weakly interacting elementary particles), where they use a detector called FASERν, which was placed in front of the main detector. FASERν was an idea considered by CERN theorist Alvaro de Rújula.

FASERν is only 25cm wide, 25cm tall and 1.35m long, and weighs at about 1.2 tons, which is very small compared to other neutrino detectors, which use a large volume of water to detect neutrinos, like the IceCube detector in the South Pole, it has a volume of a cubic kilometer. The FASERν detector works with emulsion films and tungsten plates, which act as the target and the detector to detect neutrinos interactions. When a charged particle passes through the film it leaves a track marking, but neutrinos have no electric charge, so they don't leave a trail behind on the film, but when a neutrino interacts with matter inside the detector, it produces a lot of charged particles, and those get detected by the detector, and they point to the neutrino as their source.

Credit: FASER\CERN

The detector will start up when LHC will restart in 2022 and is expected to detect around 20,000 neutrinos from 2022 to 2024, these neutrinos would have mean energy of 600GeV and 1TeV. They expect to detect about 1300 electron neutrinos, 20,000 muon neutrinos, and 20 tau neutrinos.

It will measure neutrinos cross-sections, that how often are the neutrinos interacting with matter. But why does this hold any importance? With the results, Scientists can learn about the production of energetic neutrinos in stars and cosmic sources, and for that, they need to know how likely are these particles to interact. 

Detecting neutrinos is not new, it's just that we would be able to study their interaction more precisely with FASERν.

Report on arXiv:2105.06197