Accurate setting of electron energy for demonstration of first hadron beam cooling with rf-accelerated electron bunches

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Accurate setting of electron energy for demonstration of first hadron beam cooling with rf-accelerated electron bunches

S. Seletskiy, M. Blaskiewicz, A. Drees, A. Fedotov, W. Fischer, D. M. Gassner, X. Gu, R. Hulsart, D. Kayran, J. Kewisch, C. Liu, K. Mernick, R. Michnoff, T. Miller, M. Minty, G. Robert-Demolaize, V. Schoefer, H. Song, P. Thieberger, and P. Wanderer

Phys. Rev. Accel. Beams 22, 111004 – Published 27 November 2019

Abstract

The world’s first electron cooling based on the rf acceleration of electron bunches was experimentally demonstrated at the Low Energy RHIC Electron Cooler (LEReC) at Brookhaven National Laboratory. The critical step in obtaining cooling of the Au ions in the collider with this new approach was matching the electron and ion relativistic $γ$ -factors with a relative error of less than $5 \times 10^{- 4}$ . Since the electron beam kinetic energy was just 1.6 MeV, it was required to set the absolute energy of electrons with an accuracy better than 0.8 keV. The method of setting electron energy in conventional coolers was unsuitable for LEReC and a new technique had to be developed. In this paper we describe our experience with measuring the electron beam energy at LEReC and precisely matching electron and ion $γ$ -factors, which resulted in demonstration of the cooling.

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Received 21 October 2019

DOI:https://doi.org/10.1103/PhysRevAccelBeams.22.111004

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society