Transverse Beam Size Effects on Longitudinal Profile Reconstruction

TL;DR

This paper investigates how large transverse beam sizes affect the accuracy of longitudinal profile reconstruction using coherent transition radiation autocorrelation, proposing a correction factor for improved measurements.

Contribution

It introduces a correction factor for longitudinal profile reconstruction methods accounting for large transverse beam sizes, validated through theory and experiments.

Findings

Large transverse sizes distort autocorrelation measurements

A correction factor improves profile reconstruction accuracy

Experimental results confirm theoretical predictions

Abstract

The use of coherent transition radiation autocorrelation methods to determine bunch length and profile information is examined with the compressed electron beam at the BNL ATF. A bi-gaussian fit is applied to coherent transition radiation auto-correlation data to extract the longitudinal current distribution. The effects of large transverse beam sizes are studied in theory and compared to experimental results. A suitable form of the correction factor is derived for beams with large transverse-longitudinal aspect ratios.