High energy Coulomb-scattered electrons for relativistic particle beam diagnostics

TL;DR

This paper introduces a novel diagnostic system using Coulomb-scattered electrons to precisely align electron and ion beams in the RHIC, supported by theory, commissioning results, and error analysis.

Contribution

It presents a new method for beam diagnostics based on Coulomb scattering, including theoretical development, system design, and successful application in RHIC operations.

Findings

Successful beam alignment during RHIC runs

Estimated systematic errors of the diagnostic method

Potential for future beam diagnostic applications

Abstract

A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Finally, some possible future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.