BNL, Upton, Long Island, New York, USA
The electron-ion collider eRHIC requires an electron bunch replacement about every second to maintain both high luminosity and polarization. If the bunch can be replaced in several steps, the requirements for both the electron gun and the electron accelerator are greatly reduced due to the reduced bunch charge. However, a stepwise replacement of electron bunches in eRHIC will give rise to transient effects from the beam-beam interaction that will lead to emittance growth. Such a scheme was tested using one of the RHIC electron lenses with a multiple step increase of the electron current. The test provides an order-of-magnitude estimate of the effect without any further mitigating measures.
BNL, Upton, Long Island, New York, USA
Transfer function measurements are important for characterizing betatron tunes, betatron coupling, and beam spectrum in the routine operation of the Relativistic Heavy Ion Collider (RHIC). To counteract the linear betatron coupling, we developed a technique to continuously measure the betatron coupling coefficient with a base band phase lock loop tune meter in 2006. Based on this technique, we demonstrated and built a robust tune/coupling feedback in RHIC. In this article, we revisit the BTF measurement with betatron coupling to benchmark our BTF simulation code. We also compared the values of eigenmode projection ratios from BTF with those calculated with the single particle model.
BNL, Upton, Long Island, New York, USA
LBNL, Berkeley, California, USA
In the present design of the future electron-ion collider eRHIC at the Brookhaven National Laboratory, a crossing angle of 22~mrad between the electron and proton orbits at the interaction region is adopted. To compensate the geometric luminosity loss, a local compensation scheme with two sets of crab cavities for each beam is considered. In this article, we first carry out strong-strong beam-beam simulation to study possible coherent beam-beam instability. Under the assumption of no coherent beam-beam motion, we then carry out a weak-strong beam-beam simulation to determine the long-term stability of the proton beam with the equilibrium electron beam sizes extracted from the strong-strong beam-beam simulation.
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
The electron-ion collider eRHIC aims at a luminosity around 1034cm-2sec-1, using strong cooling of the hadron beam. Since the required cooling techniques are not yet readily available, an initial version with a peak luminosity of 3*1033cm-2sec-1 is being developed that can later be outfitted with strong hadron cooling. We will report on the current design status and the envisioned path towards 1034cm-2sec-1 luminosity.
BNL, Upton, Long Island, New York, USA
RIKEN Nishina Center, Wako, Japan
Utsunomiya University, Utsunomiya, Japan
The FY18 RHIC physics program calls for Ru-Ru and Zr-Zr collisions at 100GeV using isobaric Ruthenium and Zirconium ions, each having 96 nucleons. In the injector chain, these two ions have to come from tandem and EBIS source, respectively. To reduce systematic errors in the detector, the luminosity between the two species combinations is matched as closely as possible, and the species are switched frequently. Several bunch merges are needed in the Booster and AGS to reach the desired bunch intensity for RHIC. The setup and performance of Booster and AGS with these ions are reviewed.