This chapter is the third part in a series of publications
on the Compact Muon Solenoid (CMS) detector magnetic field map creation. The
chapter focuses on pioneering work on the performance of the three-dimensional
(3D) magnetic field map in the entire volume of the CMS detector at the Large
Hadron Collider at CERN. In the CMS detector the magnetic field deflects the
charged particles produced in the proton–proton collisions at the
center-of-mass energy of 13.6 TeV. The curvatures of the charged particles allow
the measurements of the particle momenta with help of the silicon tracking
detectors located in the solenoidal magnetic flux density of 3.81 T. The
magnetic system of the CMS detector is of a heterogeneous type, where the
magnetic flux is created by a superconducting solenoid coil enclosed in a steel
flux-return yoke. The 10,000-ton steel yoke of the magnet is used as a series
of magnetized layers up to 620 mm thick which are penetrated only by muons,
making it possible to identify them and measure their momenta in a muon
spectrometer. The programs for
simulation and reconstruction of the momenta of the charged particles emerging
from collision events require the knowledge of the value of the magnetic flux
density components at the coordinates of space points along the trajectories of
the particles. To describe the CMS magnetic flux distribution in the entire CMS
detector volume, a system of the primitive 3D volumes containing the values of
the magnetic flux density measured inside the superconducting coil inner volume
and modelled outside the coil across a special mesh of reference nodes was
developed. This system, called the CMS magnetic field map, follows the
geometric features of the yoke and allows the interpolation of the magnetic
flux density between the nodes to obtain the magnetic field values at any
spatial point inside a cylinder of 18 m in diameter and 48 m in length, where
all the CMS sub-detectors are located. The geometry of the volumes is described
inside one 30° azimuthal sector of the CMS magnet. To obtain the values of the
magnetic flux density components across the entire azimuth angle of the CMS
detector, rotational symmetry is applied. Volumes are organized in a
hierarchical structure optimized for fast global searching, and caching techniques
allow simulation and track extrapolation algorithms to minimize the number of
global volume searches.
Author(s) Details:
Nicola Amapane,
INFN Sezione di Torino, I-10125 Torino, Italy and Dipartimento di
Fisica, Università di Torino, I-10125 Torino, Italy.
Vyacheslav Klyukhin,
Skobeltsyn
Institute of Nuclear Physics, Lomonosov Moscow State University, RU-119992,
Moscow, Russia. d European Organization for Nuclear Research (CERN), CH-1211
Geneva 23, Switzerland.
Please see the link here: https://stm.bookpi.org/CPPSR-V7/article/view/13455
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