Polarized electron beams in the MEIC collider ring at JLab

Abstract

The nuclear physics program of the Medium-energy Electron-Ion Collider (MEIC) at the JLab requires a highly-polarized (over 70%) electron beam with longitudinal polarization at the collision points. This can be achieved by arranging the equilibrium polarization direction to be vertical in the arcs of the figure-8 shape ring and longitudinal at collision points. The rotation of the polarization is accomplished at each energy by using universal spin rotators, each of which consists of a set of solenoids and dipoles placed at the end of each arc. To reduce the spin-orbit depolarization effect due to the synchrotron radiation, spin matching to make the sections between the rotators in the long straights spin transparent has to be considered. We present the current universal spin rotator design, address various coupling compensation schemes for the solenoids, provide polarization configurations based on the spin rotators' layout, and briefly explore the use of continuous injection of electrons from the CEBAF into the MEIC collider ring for maintaining high equilibrium polarization. This continuous injection might be less demanding than spin matching.

PERLE. Powerful energy recovery linac for experiments. Conceptual design report

“…A new concept [83] using many of the design features of this module, as well as attractive features of other JLab designs, is being developed for the JLab Electron Ion Collider [84]. Features of that module might also be considered for an eventual LHeC production cryo-module.…”

“…The SNS cryo-module is therefore a convenient model for PERLE and could be adapted with minimal changes to host the new 802 MHz 5-cell b = 1 cavities. A new concept [83] using many of the design features of this module, as well as attractive features of other JLab designs, is being developed for the JLab Electron Ion Collider [84]. Features of that module might also be considered for an eventual LHeC production cryo-module.…”

The lowQ2chicane and Compton polarimeter at the JLab EIC

“…Energy of the electrons will be similar to the existing CEBAF from 3 to 10 GeV. The protons or ions will have an energy from 20 to 100 GeV [1].…”

The low Q 2 chicane and Compton polarimeter at JLEIC

“…Energy of the electrons will be similar to the existing CEBAF from 3 to 10 GeV. The protons or ions will have an energy from 20 to 100 GeV [2]. Polarization measurement is important since the machine is designed to run at high luminosity, many measurements will be limited by systematic errors.…”