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
In this article, we study the beam-beam interaction related issues with two interaction points in the current eRHIC ring-ring design. We carried out strong-strong beam-beam simulation in a 2-d bunch intensity scan. We observed coherent beam-beam instability and emittance blowup with 2 collisions per turn at lower bunch intensities than the case with only 1 collision per turn. To deliver collisions to the two experiments simultaneously, we proposed a new bunch filling pattern to avoid 2 collisions per turn for any electron or proton bunch. We proved that the parasitic beam-beam effect with the new bunch filling pattern is negligible.
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
Cornell University, Ithaca, New York, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
JLab, Newport News, Virginia, USA
An option as an injector into the polarized-electron storage ring of eRHIC EIC is a rapid-cycling synchrotron (RCS). Cornell's 10 GeV RCS injector to CESR presents a good opportunity for dedicated polarized bunch rapid-acceleration experiments, it can also serve as a test bed for source and polarimetry developments in the frame of the EIC R&D, as polarized bunch experiments require disposing of a polarized electron source, and of dedicated polarimetry in the linac region and in the RCS proper. This is as well an opportunity for a pluri-disciplinary collaboration between Laboratories. This paper is an introduction to the topic, and to on-going activities towards that EIC R&D project.
BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.
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
A tilted bunch traversing a button beam profile monitor will produce signals on opposite pickup electrodes that will have different degrees of distortion depending on the tilt angle. In particular, the zero-crossing time difference between the two signals will be approximately proportional to the tilt angle. We perform simulations to study this effect as a possible diagnostic tool for measuring the crabbing angles in a future electron-ion collider.
BNL, Upton, Long Island, New York, USA
The electron-ion collider eRHIC requires a variety of kickers and septa for injection and extraction of beams throughout the entire collider complex. We plan to use pulsed systems for beam injection and extraction in Electron RCS, Electron Storage Ring, and Hadron ring. In this paper, we describe the pulsed systems required for beam transfer in the eRHIC Ring-Ring Pre-conceptual Design. We will outline the parameter ranges, technology choices, and opportunities for research and development in pulsed power technology.