Optimization of a dedicated bio-imaging beamline at the European X-ray FEL

TL;DR

This paper proposes an optimized design for a bio-imaging beamline at the European XFEL, enhancing performance and operational efficiency through improved monochromator design and high electron energy operation.

Contribution

It introduces a novel undulator source design with advanced monochromators, enabling higher electron energy and peak power, tailored for bio-imaging applications.

Findings

Achieves 2 TW FEL power in 3-5 keV range

Enables operation at 17.5 GeV electron energy

Maintains performance despite spatiotemporal coupling effects

Abstract

We recently proposed a basic concept for design and layout of the undulator source for a dedicated bio-imaging beamline at the European XFEL. The goal of the optimized scheme proposed here is to enable experimental simplification and performance improvement. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Based on the use of an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. An advantage of operating at such high electron energy is the increase of the X-ray output peak power. Another advantage is that 17.5 GeV is the preferred operation energy for SASE1 and SASE2 beamline users. Since it will be necessary to run all the XFEL lines at the same electron energy, this choice will reduce the interference with other undulator lines and increase the total amount of scheduled beam time. In this work we also propose a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. Our analysis indicates that this distortion is easily suppressed by the right choice of diamond crystal planes and that the proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV - 5 keV photon energy range, which is the most preferable for single biomolecule imaging.