Evaluating the dynamic aperture evaluation for the new RHIC 250 GeV polarized proton lattice

To increase luminosity in the Relativistic Heavy Ion Collider's (RHIC's) polarized proton 250 GeV operations, we are considering reducing β* to 0.65 m at the interaction points (IPs), and increasing bunch intensity. The new working point near the 2/3 integer will used on the ramp to preserve polarization. In addition, we plan to adjust the betatron-phase advances between IP6 and IP8 to (k+1/2)*π so to lower the dynamic beta-beat from the beam-beam interaction. The effects of all these changes will impact the dynamic aperture, and hence, it must be evaluated carefully. In this article, we present the results of tracking the dynamic aperture with the proposed lattices.