Characterisation of plastic scintillator paddles and lightweight MWPCs for the MID subsystem of ALICE 3

Abstract

The ALICE collaboration is proposing a completely new detector, ALICE 3, for operation during the LHC Runs 5 and 6. One of the ALICE~3 subsystems is the Muon IDentifier detector (MID), which has to be optimised to be efficient for the reconstruction of $J/\psi$ at rest (muons down to $p_{\rm T}\approx1.5$ GeV/$c$) for $|\eta|<1.3$. Given the modest particle flux expected in the MID of a few Hz/cm$^2$, technologies like plastic scintillator bars ($\approx1$ m length) equipped with wavelength-shifting fibers and silicon photomultiplier readout, and lightweight Multi-Wire Proportional Chambers (MWPCs) are under investigation. To this end, different plastic scintillator paddles and MWPCs were studied at the CERN T10 test beam facility. This paper reports on the performance of the scintillator prototypes tested at different beam momenta (from 0.5 GeV/$c$ up to 6 GeV/$c$) and positions (horizontal, vertical, and angular scans). The MWPCs were tested at different momenta (from 0.5 GeV/$c$ to 10 GeV/$c$) and beam intensities, their efficiency and position resolutions were verified beyond the particle rates expected with the MID in ALICE 3.