Updated magnetic rigidity calibration of ARIS

The Facility for Rare Isotope Beams (FRIB) enables groundbreaking research in nuclear physics, astrophysics, and fundamental interactions, as well as the societal applications of this work. Critical to the science program at FRIB is the Advanced Rare Isotope Separator (ARIS), which separates, identifies, and purifies fragments produced via projectile fragmentation and fission using a variety of beamline elements, including eight superconducting dipole magnets. An accurate magnetic rigidity calibration of these dipole magnets is crucial for obtaining peak fragment yields with optimal transport conditions in minimal time and comparing to simulations. This work reports on the use of the FRIB linear accelerator to provide charge states of a U-238 beam of known energies, with accuracy of 0.1%, to calibrate the ARIS dipole field versus effective bend radius over a range of magnetic rigidities. Due to saturation of the iron in the dipoles, the effective radius varies significantly, especially above about 1.2 T. Details of the procedure and results will be presented.