eRHIC Project Research Articles

Main Magnets and Correctors for the CBETA and eRHIC Projects, and Hadron Facilities

The CBETA (Cornell Brookhaven Experimental Test Accelerator) project described in reference C. Mayes (2015) is a prototype electron accelerator for the proposed eRHIC (electron Relativistic Heavy Ion Collider) project, described in reference E. C. Aschenauer (2014). An Energy Recovery Linac (ERL) in combination with a recirculating beam line which is based on the Fixed Field Alternating Gradient (FFAG) principle constitute the electron accelerator. The FFAG beam line of the electron accelerator is comprised of cells consisting of one focusing and one defocusing quadrupoles which are designed as Halbach type permanent magnet quadrupoles which are discussed in reference K. Halbach (1980). Window frame electromagnets surrounding the Halbach magnets will be used as normal and skew dipoles correctors and quadrupole correctors. A Halbach magnet in combination with low field electromagnets to act as dipole and/or quadrupole correctors can also be used in the proposed eRHIC project as well as other hadrons facilities like RHIC. We will discuss some of the advantages the Halbach type permanent magnets have over electromagnets and provide experimental and theoretical evidence of these advantages.

The eRHIC Project

The eRHIC project plans to expand Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC) with a high-intensity electron beam. Building on the exciting discoveries of RHIC, CERN, HERA and others, eRHIC will break new ground in collider luminosity and will push the frontiers of knowledge in nucleon and nuclear structure and in spin physics. The varied eRHIC physics programme and the proposed machine design will be presented and discussed.

Self-polarizing electron ring for eRHIC project

We present the electron storage ring for an arrangement of electron–proton and electron–ion collisions at RHIC. High degree of radiative electron polarization will be achieved at the beam energy range 5–10 GeV with characteristic time about 10 min. Required luminosity of polarized e–p collisions for studies of deep inelastic scattering is 1×10 33 cm −2 s −1 in the SCM energy range 15–100 GeV.

QCD analysis of spin structure function data from present and prospective measurements

We present an updated QCD analysis in next to leading order in α s of all available g 1 spin structure function data. The first moment of the polarized gluon distribution is determined from the fit with a statistical error of 30%. The results of the fit are used to project measurements in the kinematic region of an electron-proton collider such as suggested by the e-RHIC project or a polarized HERA. The new data obtained from a collider like e-RHIC will improve our knowledge on the low x behavior of g 1 and will further reduce the error on the first moment of the polarized gluon distribution to about 10%.