Accurate single-shot measurement technique for the spectral distribution of GeV electron beams from a laser wakefield accelerator

TL;DR

This paper introduces a novel single-shot measurement technique using a dipole magnet spectrometer with scintillation screens, enabling precise spectral characterization of GeV electron beams from laser wakefield accelerators, even with beam fluctuations.

Contribution

The paper presents an optimized algorithm and numerical code for accurate, single-shot spectral measurement of LWFA electron beams, validated through simulations and applied to multi-GeV experiments.

Findings

Enhanced accuracy in spectral measurement of LWFA electron beams.

Effective characterization despite shot-to-shot pointing fluctuations.

Successful application to multi-GeV electron beams from high-power lasers.

Abstract

We present a technique, based on a dipole magnet spectrometer containing multiple scintillation screens, to accurately characterize the spectral distribution of a GeV electron beam generated by laser wakefield acceleration (LWFA). An optimization algorithm along with a numerical code was developed for trajectory tracing and reconstructing the electron beam angle, divergence, and energy spectrum with a single-shot measurement. The code was validated by comparing the results with the Monte-Carlo simulation of electron beam trajectories. We applied the method to analyze data obtained from laser wakefield acceleration experiments performed using a multi-Petawatt laser to accelerate electron beams to multi-GeV energy. Our technique offers improved accuracy to faithfully characterize electron beams with non-negligible shot-to-shot beam pointing fluctuations, particularly in the state-of-the-art multi-GeV LWFA experiments performed to push the energy frontier.