A higher momentum aperture lattice proposed for the sPHENIX background problem

During the 2024 Au+Au 100 GeV physics run, the sPHENIX MVTX detector experienced background issues originating from the Yellow beam, leading to frequent auto-recoveries during streaming mode operation. One hypothesis attributes the background to the loss of off-momentum particles. An evaluation of the momentum apertures in both RHIC rings revealed that the Yellow ring had a worse momentum acceptance compared to the Blue ring. To address this, a new lattice design with a reduced W-function was proposed. This report presents the momentum aperture comparison between the two rings, the proposed new lattice design considering additional constraints, and the resulting momentum and dynamic apertures.