Measurement of the muon flux at the SND@LHC experiment

Abstract

The Scattering and Neutrino Detector at the LHC (SND@LHC) started taking data at the beginning of Run 3 of the LHC. The experiment is designed to perform measurements with neutrinos produced in proton-proton collisions at the LHC in an energy range between 100 GeV and 1 TeV. It covers a previously unexplored pseudo-rapidity range of $7.2<\eta <8.4$. The detector is located 480 m downstream of the ATLAS interaction point in the TI18 tunnel. It comprises a veto system, a target consisting of tungsten plates interleaved with nuclear emulsion and scintillating fiber (SciFi) trackers, followed by a muon detector (UpStream, US and DownStream, DS). In this article we report the measurement of the muon flux in three subdetectors: the emulsion, the SciFi trackers and the DownStream Muon detector. The muon flux per integrated luminosity through an 18$\times$18 cm${}^2$ area in the emulsion is: $$\begin{array}{c}\hfill 1.5\pm 0.1(\text{stat})\times {10}^4{\text{fb/cm}}^2.\end{array}$$The muon flux per integrated luminosity through a 31$\times$31 cm${}^2$ area in the centre of the SciFi is: $$\begin{array}{c}\hfill 2.06\pm 0.01(\text{stat})\pm 0.12(\text{sys})\times {10}^4{\text{fb/cm}}^2\end{array}$$The muon flux per integrated luminosity through a 52$\times$52 cm${}^2$ area in the centre of the downstream muon system is: $$\begin{array}{c}\hfill 2.35\pm 0.01(\text{stat})\pm 0.10(\text{sys})\times {10}^4{\text{fb/cm}}^2\end{array}$$The total relative uncertainty of the measurements by the electronic detectors is 6$\%$ for the SciFi and 4$\%$ for the DS measurement. The Monte Carlo simulation prediction of these fluxes is 20–25$\%$ lower than the measured values.