The CMS Magnetic Field Map Performance

• Published in: IEEE transactions on applied superconductivity Vol. 20; no. 3; pp. 152 - 155
• Main Authors: Klyukhin, V I, Amapane, N, Andreev, V, Ball, A, Cure, B, Herve, A, Gaddi, A, Gerwig, H, Karimaki, V, Loveless, R, Mulders, M, Popescu, S, Sarycheva, L I, Virdee, T
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2010; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Collision mitigation; Cylinders; Detectors; Electromagnetism; Flux-loops; hall probes; Large Hadron Collider; Magnetic field measurement; magnetic field measurements; Magnetic fields; Magnetic flux; Mathematical models; Mesons; NMR probes; Parametrization; Solenoids; Studies; Superconducting magnets; superconducting solenoid; Superconducting transmission lines; Superconductivity; Yokes
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2010.2041200

The Compact Muon Solenoid (CMS) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000-ton return yoke made of construction steel. Accurate characterization of the magnetic field everywhere in the CMS detector is required. During two major tests of the CMS magnet the magnetic flux density was measured inside the coil in a cylinder of 3.448 m diameter and 7 m length with a specially designed field-mapping pneumatic machine as well as in 140 discrete regions of the CMS yoke with NMR probes, 3-D Hall sensors and flux-loops. A TOSCA 3-D model of the CMS magnet has been developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. A volume based representation of the magnetic field is used to provide the CMS simulation and reconstruction software with the magnetic field values. The value of the field at a given point of a volume is obtained by interpolation from a regular grid of values resulting from a TOSCA calculation or, when available, from a parameterization. The results of the measurements and calculations are presented, compared and discussed.