Improving Optics Control and Measurement at RHIC

TL;DR

This paper presents methods to improve linear optics control and measurement at RHIC, achieving significant reduction in beta beat and better $s^*$ measurement consistency to optimize luminosity.

Contribution

It introduces a sensitivity matrix approach and a one-turn map method for linear optics measurement, enhancing control accuracy at RHIC.

Findings

Achieved 10% reduction in beta beat.

Improved $s^*$ measurement stability.

Validated methods for RHIC optics control.

Abstract

In order to aid in luminosity maximization at the interaction point (IP), the collision location $s_{IP}$ must be equivalent to the location of the minimum value of the beta function $s^*$. Accurate optics measurements and $s^*$ movements are therefore essential to luminosity optimization. However, according to current Relativistic Heavy Ion Collider (RHIC) operations measurements, average horizontal beta beat measurements between operating IPs are around $20\%$ along with significant variation in $s^*$ measurements. A sensitivity matrix was shown to successfully move $s^*$ and the linear optics to their desired values using power supply currents at the 8 o'clock interaction region (IR8). A method to measure the linear optics using the one-turn map within IRs was explored and compared with other mature methods. An error analysis was also included for all optics measurements methods. Through these methods, a $10\%$ beat reduction was consistently achieved while moving $s^*_x$ as well significant improvement to variations in $s^*$ measurements. These methods used at the RHIC control room will be updated for future linear optics analysis and control.