Shan Liu

Single-shot sorting of Mössbauer time-domain data at X-ray free-electron lasers

Miriam Gerharz, Willi Hippler, Berit Marx-Glowna, Sakshath Sadashivaiah et autres

Mössbauer spectroscopy is widely used to study structure and dynamics of matter with remarkably high energy resolution, provided by the narrow nuclear resonance line widths. However, the narrow width implies low count rates, such that experiments commonly average over extended measurement times …

Control of bandwidth and signal-to-noise ratio for hard-x-ray self-seeded free-electron lasers

Tianyun Long, Ye Chen, Winfried Decking, Gianluca Geloni et autres

Hard-x-ray self-seeded (HXRSS) free-electron lasers (FELs) can provide nearly fully coherent radiation pulses in the hard-x-ray domain with extremely high spectral density, which opens up new possibilities for a wide range of scientific applications such as resonant inelastic x-ray scattering, nuclear resonance …

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Updates on the Hard X-Ray Self-Seeding at the European XFEL

Shan Liu, Gianluca Geloni, Tianyun Long, Weilun Qin et autres

1. The European XFEL is a state-of-the-art hard X-ray free-electron laser (FEL) facility powered by a high-energy superconducting linear accelerator. Operating at megahertz repetition rates, it can...

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Self-Seeding: Enhancing Spectral Brightness in Hard X-Ray Free-Electron Lasers

Shan Liu, Gianluca Geloni

This special issue of SRN highlights a groundbreaking technique developed over the past decade at hard X-ray Free-Electron Lasers (XFELs): Hard X-ray Self-Seeding (HXRSS).HXRSS is deeply influencing experimental techniques that demand high photon flux per unit bandwidth, such as Mössbauer spectroscopy, inelastic …

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Terawatt-attosecond hard X-ray free-electron laser at high repetition rate

Jiawei Yan, Weilun Qin, Ye Chen, Winfried Decking et autres

Abstract Ångstrom and attosecond are the fundamental spatiotemporal scales for electron dynamics in various materials. Although attosecond pulses with wavelengths comparable to the atomic scales are expected to be a key tool in advancing attosecond science, producing high-power hard X-ray attosecond pulses …

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A Millimeter-Wave Fixed-Frequency Beam-Steering Leaky-Wave Antenna Based on 2-Bit Phase Control

Shan Liu, Zheng Li, Junhong Wang

A millimeter-wave fixed-frequency beam-steering leaky-wave antenna (L WA) is presented in this article. The designed LWA adopts an air-filled gap waveguide as transmission structure to reduce the dielectric loss. By changing the bias voltage to control the ON/OFF state of the diodes …

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Cascaded hard X-ray self-seeded free-electron laser at megahertz repetition rate

Shan Liu, Christian Grech, Marc Walter Guetg, Suren Karabekyan et autres

Abstract High-resolution X-ray spectroscopy in the sub-nanosecond to femtosecond time range requires ultrashort X-ray pulses and a spectral X-ray flux considerably larger than that presently available. X-ray free-electron laser (XFEL) radiation from hard X-ray self-seeding (HXRSS) setups has been demonstrated in the …

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Resonant X-ray excitation of the nuclear clock isomer 45Sc

Yuri V. Shvyd'ko, Ralf Röhlsberger, Olga A. Kocharovskaya, Jörg Evers et autres

Abstract Resonant oscillators with stable frequencies and large quality factors help us to keep track of time with high precision. Examples range from quartz crystal oscillators in wristwatches to atomic oscillators in atomic clocks, which are, at present, our most precise time …

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Superconducting undulator activities at the European X-ray Free-Electron Laser Facility

S. Casalbuoni, Suren Abeghyan, Levon Alanakyan, Johann Baader et autres

For more than 5 years, superconducting undulators (SCUs) have been successfully delivering X-rays in storage rings. The European X-Ray Free-Electron Laser Facility (XFEL) plans to demonstrate the operation of SCUs in X-ray free-electron lasers (FELs). For the same geometry, SCUs can reach …

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Ku/Ka Dual-Band Shared-Aperture Leaky-Wave Antenna With Fixed-Frequency and Wide-Angle Beam Scanning Based on Ridged SIW

Bang Wei, Zheng Li, Shanzhe Wang, Shan Liu et autres

In this communication, a novel ridged substrate integrated waveguide (RSIW) structure is reported to realize the transmission of electromagnetic waves in dual bands in a shared aperture. The structure is consisting of two substrate integrated waveguides (SIWs) operating in Ka- and Ku-bands, …

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Cascaded hard X-ray self-seeded free-electron laser at MHz-repetition-rate

Shan Liu, Christian Grech, Marc Walter Guetg, Suren Karabekyan et autres

Abstract The European XFEL is currently the only high-repetition rate hard X-ray free electron laser (FEL) facility in operation worldwide. We significantly improved its capabilities by installing a cascaded Hard X-ray Self-Seeding (HXRSS) system, composed of two single-crystal monochromators. With this system, …

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A fixed-frequency Beam-Scanning Leaky-Wave Antenna Base on Phase and Amplitude Control

Shan Liu, Zheng Li, Junhong Wang

A novel fixed-frequency beams canning leaky-wave antenna (LWA) based on dual control of amplitude and phase is proposed. The antenna adopts a gap wave waveguide (GGW) as the basic transmission structure and consists of SO patch elements. Each patch is excited by …

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