Beam-beam observations in the RHIC

TL;DR

This paper reviews beam-beam effects observed in RHIC's polarized proton operations, analyzing particle loss mechanisms, emittance growth, and operational limits to improve collider performance.

Contribution

It provides a comprehensive review of beam-beam observations, mechanisms of particle loss, and discusses solutions to current operational limits in RHIC p-p runs.

Findings

Maximum beam-beam tune shift reached 0.018

Beam-beam interactions cause emittance growth and short lifetimes

Intra-beam scattering contributes significantly to emittance increase

Abstract

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been in operation since 2000. Over the past decade, the luminosity in the polarized proton (p-p) operations has increased by more than one order of magnitude. The maximum total beam-beam tune shift with two collisions has reached 0.018. The beam-beam interaction leads to large tune spread, emittance growth, and short beam and luminosity lifetimes. In this article, we review the beam-beam observations during the previous RHIC p-p runs. The mechanism for particle loss is presented. The intra-beam scattering (IBS) contributions to emittance and bunch length growths are calculated and compared with the measurements. Finally, we will discuss current limits in the RHIC p-p operations and their solutions.