Calculation of Forces to the High Granularity Calorimeter Stainless Steel Absorbers Misaligned inside the CMS Superconducting Coil

Abstract

The general-purpose Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN includes the hadronic calorimeter to register the energies of the charged and neutral hadrons produced in the proton-proton collisions at the LHC at a centre of mass energy 13.6 TeV. The calorimeter is located inside the superconducting solenoid of 6 m in diameter and 12.5 m in length operating with a direct current of 18.164 kA that creates the central magnetic flux density of 3.81 T. To fit optimally to the high pileup and high radiation environment of the High Luminosity LHC, the existing CMS endcap calorimeter will be replaced with a new high granularity calorimeter (HGCal) comprising the electromagnetic and hadronic sections. The hadronic section in each of two endcaps of the HGCal will include 22 stainless steel absorber plates with a relative permeability value of 1.000588 at to the central magnetic flux density of 3.81 T. The calculation of the electromagnetic forces to the absorber plates due to orthogonal and angular misalignments of the HGCal endcaps with respect to the coil axis is performed with a three-dimensional computer model of the CMS magnet using the method of calculation described earlier.