Study of high-energy neutrinos in the FASER experiment at the LHC

FASER is a new experiment at the Large Hadron Collider (LHC) aiming to search for light, weakly interacting new particles, complementing other experiments. The particle detector will be located 480 m downstream of the ATLAS interaction point. In addition to searches for new particles, we also aim to study high-energy neutrinos of all flavors, as there is a huge flux of neutrinos at this location. To date, muon-neutrino cross-section data, obtained with accelerator-based neutrino beams, exist up to 350 GeV, but we are still missing data at the TeV energy scale. At LHC-FASER, the neutrino cross sections will be measured in the currently unexplored energy range between 350 GeV and 6 TeV. In particular, tau neutrinos will be measured at the highest energy ever. Furthermore, the channels associated with heavy quark (charm and beauty) production can be studied. As a feasibility study, we performed a test run in 2018 at the proposed detector location, using a 30 kg lead/tungsten emulsion-based neutrino detector. We collected 12.5 fb(-1) of data, and expect a few tens of neutrino interactions to have been recorded in the detector. From 2021 to 2023 during Run 3 of the 14 TeV LHC, we are planning to deploy an emulsion detector with a target mass of 1.2 tons, possibly coupled with the FASER magnetic spectrometer, which would yield roughly 1,300 nu(e), 20,000 nu(mu), and 20 nu(tau) interacting in the detector. Here, we present an overview of the FASER neutrino program, as well as a preliminary analysis of the 2018 test run.