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A compact and cost-effective hard X-ray free-electron laser driven by a high-brightness and low-energy electron beam

Abstract

We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-Å wavelength with pulse energies of more than 500 μJ, pulse durations of ~30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of ~2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation.

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Fig. 1: Schematic of SwissFEL.
Fig. 2: Electron and photon beam properties at SwissFEL.
Fig. 3: Transient response in Bi(111) peak intensity displaying a coherent optical phonon, displacively excited by an 800-nm pulse.
Fig. 4: SwissFEL special operation modes.

Data availability

The data that support the figures in this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The FEL code Genesis 1.3 is available at http://genesis.web.psi.ch.

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Acknowledgements

We thank all the technical groups involved in the construction, installation and operation of SwissFEL. We also thank K. Sokolowski Tinten and M. Horn-von Hoegen for providing the thin-film Bi samples used in the timing characterization. This work has been supported by SNF grant no. 200021 175498 and no. 51NF40-183615 (NCCR:MUST). Moreover, this project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 695197 DYNAMOX).

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E.P. wrote the initial version of the manuscript with the help of P.J., R.I., H.T.L., F.L., C.J.M., S. Reiche, T. Schietinger and H.-H.B. All authors contributed to the final version of the document. All authors participated in the design, construction or commissioning of SwissFEL. F.L. was the machine coordinator of SwissFEL. H.-H.B., R.A. and L.P. were the project leaders of SwissFEL.

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Correspondence to Eduard Prat.

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Prat, E., Abela, R., Aiba, M. et al. A compact and cost-effective hard X-ray free-electron laser driven by a high-brightness and low-energy electron beam. Nat. Photonics 14, 748–754 (2020). https://doi.org/10.1038/s41566-020-00712-8

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