The CMS Magnetic Field Map (I). Design and Description of the CMS Magnetic System Model

Abstract

This review is the first part in a series of papers on the Compact Muon Solenoid (CMS) detector magnetic field map creation. The review describes the composition of the CMS detector and the methodology for modelling the heterogeneous CMS magnetic system, starting with the formulation of the magnetostatics problem for modelling the magnetic flux of the CMS superconducting solenoid enclosed in a steel flux-return yoke. The review includes a section on the magnetization curves of various types of steel used in the CMS magnet yoke. The evolution of the magnetic system model over 20 years is presented in the discussion section and is well illustrated by the CMS model layouts and the magnetic flux distribution. Different kinds of geometrical and scalar magnetic potential symmetries were used to build the CMS magnet model in a series of successive iterations. This has made it possible to characterize the magnetic flux in the CMS detector for an extended period using as little computational power as possible, in line with current computer technology capabilities.