A SHIFT of Perspective: Observing Neutrinos at CMS and ATLAS

We investigate the physics potential of SHIFT@LHC, a proposed gaseous fixed target installed in the LHC tunnel, as a novel source of detectable neutrinos. Using simulations of proton-gas collisions, hadron propagation, and neutrino interactions, we estimate that $O(10^4)$ muon-neutrino and $O(10^3)$ electron-neutrino interactions, spanning energies from 20 GeV to 1 TeV, would occur in the CMS and ATLAS detectors with 1% of the LHC Run-4 integrated luminosity. This unique configuration provides access to hadron production in the pseudorapidity range 5<$\eta$<8, complementary to existing LHC detectors. If realized, this would mark the first detection of neutrinos in a general-purpose LHC detector, opening a new avenue to study neutrino production and interactions in a regime directly relevant to atmospheric neutrino experiments.