Speaker
Description
The Thomas Jefferson National Accelerator Facility (JLab) has developed a unique spectrometer system to study the weak interaction between electrons. The "Measurement of Lepton-Lepton Electroweak Reaction" (MOLLER) experiment, utilizing JLab's recent 12 GeV electron beam upgrade, is scheduled to operate for three years. Central to the MOLLER experiment are five water-cooled toroidal magnets, each with a unique geometry and seven-fold symmetry, designed to focus the particles. These magnets generate the magnetic field needed to separate incident beam electrons scattered from target electrons (Møller scattering) and protons (elastic e-p scattering) within a target. This paper details the magnet field measuring technique developed to map all five MOLLER toroidal magnets at multiple locations within the open sector and along the bore. It covers the design, mounting, and operation of the probe, along with the calibration procedure to determine the field and to prepare field map for GEANT4 analysis. Additionally, the paper addresses the challenges of accurately measuring low magnetic fields.
Index Terms – magnets, spectrometer, toroid, field mapping, calibration
Acknowledgement – This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
