Correcting for helicity-correlated beam parameters in the parity-violating electron scattering experiment of CREX at Jefferson Lab.

In high precision parity-violating experiments such as CREX at Jefferson Lab, understanding and correcting for differences in helicity-correlated beam parameters is essential in removing false asymmetries from the experimental parity-violating measurement. To accurately measure possible helicity-correlated beam parameters such as beam position, energy, and angle, these parameters are deliberately modulated in a controlled way and the response is measured in a series of monitors located along the beam line of the accelerator. Invertibility of the response matrix depends on the accelerator configuration and is required to express false asymmetries in terms of the beam parameters. We continuously monitor components of this response matrix to ensure invertibility and make necessary adjustments during the experimental running to accommodate changes in accelerator configuration. This system was successful in suppressing the false asymmetries in CREX to the level required for the experiment. The elements of this modulation system, monitoring strategy, and its controls  will be discussed.