Analysis of muon production in P42 and their effect on the M2 beamline

During the 2022 operation of the P42 beamline, high radiation levels were observed at the ramp to EHN1 and the M2 tunnel in CERN’s North Area. This study employs BDSIM simulations to investigate the influence of muons originating from P42 on the M2 beamline, which are located in the North Area at CERN. The simulations reveal that muons effectively reach the CEDAR region of M2, exhibiting a uniform distribution at approximately 10^6 muons per dm per primary proton on T4, both in x and y. However, within a 1-meter radius of M2, this uniform distribution ceases due to the presence of magnetic fields of the M2 magnets, causing the deflection of muons away from this area. The majority of these muons possess momenta less than 20 GeV/c.