Novel optical interferometry of synchrotron radiation for absolute electron beam energy measurements

TL;DR

This paper introduces a new optical interferometry technique using synchrotron radiation for precise absolute electron beam energy measurements, demonstrated with a 195 MeV beam at MAMI, achieving high statistical precision.

Contribution

The paper presents a novel interferometric method for absolute electron beam energy measurement using optical synchrotron radiation and a high-resolution grating monochromator, with demonstrated experimental results.

Findings

Achieved 1 keV statistical precision in 1 hour

Systematic uncertainties of 700 keV identified

Method applicable to other accelerators like MESA

Abstract

A novel interferometric method is presented for the measurement of the absolute energy of electron beams. In the year 2016, a pioneering experiment was performed using a 195 MeV beam of the Mainz Microtron (MAMI). The experimental setup consisted of two collinear magnetic undulators as sources of coherent optical synchrotron light and a high-resolving grating monochromator. Beam energy measurements required the variation of the relative undulator distance in the decimeter range and the analysis of the intensity oscillation length in the interference spectrum. A statistical precision of 1 keV was achieved in 1 hour of data taking, while systematic uncertainties of 700 keV were present in the experiment. These developments aim for a relative precision of $10^{-5}$ in the absolute momentum calibrations of spectrometers and high-precision hypernuclear experiments. Other electron accelerators with beam energies in this regime such as the Mainz Energy Recovering Superconducting Accelerator (MESA) might benefit from this new method.