ROSA: Reconstruction of Spectrogram Autocorrelation for Self-Amplified Spontaneous Emission Free-Electron Lasers

TL;DR

This paper introduces a cost-effective spectrogram autocorrelation method for analyzing the temporal properties of SASE pulses in XFELs, using measured spectra to infer pulse duration and coherence.

Contribution

It proposes a novel technique that reconstructs the autocorrelation of SASE FEL pulses from spectral measurements, enhancing diagnostics without complex equipment.

Findings

Enables pulse duration estimation from spectral data

Provides insights into the temporal coherence of SASE pulses

Offers a practical diagnostic tool for XFEL experiments

Abstract

In recent years X-ray Free Electron Lasers (XFELs) proved to be unmatched sources of ultrashort pulses of spatially coherent quasimonochromatic X-ray radiation. Diagnostics of XFEL emission properties, in particular pulse duration, spectrum and temporal profile is extremely important in order to analyze the experimental results. In this paper we propose a cost-effective method to examine these properties of Self-Amplified Spontaneous Emission (SASE) pulses. It only requires an ensemble of measured SASE spectra and provides the temporal autocorrelation of the ensemble-averaged Wigner distribution of SASE FEL pulses.