Impact of the Material Choice for the Solenoid Magnet of an EIC Central Detector on Muon Tracks

Two superconducting magnet technologies are currently being considered for the central solenoid of a second EIC detector: Al-stabilized and Co-stabilized Nb-Ti superconductors. The former utilizes minimum material and weight, which increase the magnet’s transparency for charged particles, but it comes with high monetary costs. The latter has lower transparency but has a lower cost and could lead to substantial cost savings. Since a muon detector would be placed outside of the solenoid, the effect of a Co-based solenoid on the muon identification needs to be studied. The goal of this research is to compare the effect of copper and aluminum magnet materials on muon tracks by using Geant-4 simulated data. Muons with momenta 0.5 – 4.0 GeV/c and pseudorapidity of -1 – 1 were generated and propagated through the Fun4All CORE detector simulation. The change in the components of the muon three-momentum vector through the magnet was studied for both materials. The widths of the event distributions over these variables are used to quantify the magnet material effect and are presented here as functions of muon momentum and pseudorapidity. Our estimates are critical for the choice of magnet material for the second EIC detector and for the design of a muon detection system there.