Science coffee

The FASER experiment: A new LHC detector in search for long lived particles

by Claire Antel (Université de Genève)

Fysiska institutionen-Physics Department Hus H

Fysiska institutionen-Physics Department Hus H

Large experiments at the LHC have focussed on searching for new particles at TeV mass scale with order of ~1 couplings to the Standard Model and produced at high transverse momenta relative to the beam axis. After two completed data-taking periods at the LHC, no hints of new particles at such scales have appeared, leading us to increasingly consider phase space beyond the sensitivity of ATLAS and CMS. The very forward region of these large detectors presents one such region, from which in Run 3 alone we expect O(10^16) inelastic events that mostly pass by undetected. FASER is a new LHC experiment that will take advantage of this ‘blind spot’. The ForwArd Search ExpeRiment will be positioned 480 downstream from ATLAS situated on the collision axis line of sight. It will use trackers, scintillators and calorimetry to have sensitivity to hypothetical light, highly boosted signals from long-lived particles such as dark photons and axions that travel almost parallel to the beam axis from the proton interaction point at ATLAS. The experiment was approved in March 2019 and is to be installed underground in 2020. I will describe the FASER detector in detail, illustrate what makes it a low risk and high gain experiment