Intrabeam scattering studies with large-emittance-ratio ion beams in the relativistic heavy ion collider and implications for the electron-ion collider

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 × 10 34 cm − 2 s − 1 . To reach such high 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. 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. In this article, we present results of intrabeam scattering (IBS) measurements and modeling for large-emittance-ratio gold ion beams, both without and with controlled betatron coupling. To model the IBS growth, we use the formulas developed by Lebedev and Nagaitsev.