Intrabeam scattering studies with large-emittance-ratio ion beams in the Relativistic Heavy Ion Collider, and implications for the Electron-Ion Collider

Abstract: The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized, high-energy electron beams with hadron beams, achieving peak luminosities of up to $1.0 \times 10<sup>{34}$ cm$<sup>{-2}$ s$<sup>{-1}$. To reach such luminosity, the EIC will employ flat-beam collisions at the interaction point. The design transverse emittance ratio will be about 10:1 in the Hadron Storage Ring (HSR). Thanks to stochastic cooling and precise decoupling, we successfully generated and accelerated gold ion beams with a large emittance ratio of 11:1 in the Relativistic Heavy Ion Collider (RHIC). In this article, we present results of intrabeam scattering (IBS) measurements and modeling for large-emittance-ratio gold ion beam, both with and without controlled betatron coupling. To model the IBS growth, we use the formulas developed by Lebedev and Nagaitsev.