Commissioning Process for the High Rigidity Spectrometer (HRS)*

The HRS plays a key role in the scientific program of the Facility for Rare Isotope Beams (FRIB). It focuses and separates the products of nuclear reactions and thus provides insight into the reaction mechanisms and the nuclear structures involved. Our goal is to design and simulate the calibration process of the HRS. The work will allow us to reliably correct errors between reality and prediction and avoid the undesired first-order optical properties.

The approach of calibration is developed based on the work of re-tuning the SHARAQ spectrometer by Y. Sasamoto et al. The couplings between each mapping term and each quadrupole field strength are extracted and summarized in a coupling matrix. By inverting the matrix, we are able to solve the magnetic field corrections for desired first-order mapping terms. To simulate the experimental results realistically, a Monte-Carlo approach is applied. Random errors are also added to the tracking data to include the finite resolution of the detectors.

We successfully developed the calibrate the process. After ten iterations, mapping terms decrease significantly and have an average of 0.061. The algorithm is proven to calibrate the system reliably in repeated, randomized trials when the pole-tip field error is smaller than 0.10T.