Energy Calibration of the JLab Bremsstrahlung Tagging System
  In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with $e^+e^-$ pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of $\pm 0.1% E_\gamma$. The absolute energy scale was determined using the $e^+e^-$ rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be $<3$ MeV. 
S. Stepanyan, S. Boyarinov, H. Egiyan, L. Guo, D. Dale, M. Gabrielyan,   L. Gan, A. Gasparian, A. Glamazdin, B. Mecking, I. ...