Photoelectron spectroscopy as a non-invasive method to monitor SASE-FEL spectra

Wellhöfer, M.; Hoeft, J.; Martins, M.; Würth, W.; Braune, Markus; Viefhaus, Jens; Tiedtke, K.; Richter, M.

doi:10.1088/1748-0221/3/02/p02003

Cited by 20 publications

(9 citation statements)

References 21 publications

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“…The latter one includes the response time of the MCP electron detector and the resolution of the analog-to-digital (ADC) converter [106]. To improve the energy resolution, retardation potentials can be applied to increase the flight time of the electrons, before they enter the drift tube.…”

Section: Measurement Resolutionmentioning

confidence: 99%

Ultrashort Free-Electron Laser X-ray Pulses

et al. 2017

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For the investigation of processes happening on the time scale of the motion of bound electrons, well-controlled X-ray pulses with durations in the few-femtosecond and even sub-femtosecond range are a necessary prerequisite. Novel free-electron lasers sources provide these ultrashort, high-brightness X-ray pulses, but their unique aspects open up concomitant challenges for their characterization on a suitable time scale. In this review paper we describe progress and results of recent work on ultrafast pulse characterization at soft and hard X-ray free-electron lasers. We report on different approaches to laser-assisted time-domain measurements, with specific focus on single-shot characterization of ultrashort X-ray pulses from self-amplified spontaneous emission-based and seeded free-electron lasers. The method relying on the sideband measurement of X-ray electron ionization in the presence of a dressing optical laser field is described first. When the X-ray pulse duration is shorter than half the oscillation period of the streaking field, few-femtosecond characterization becomes feasible via linear streaking spectroscopy. Finally, using terahertz fields alleviates the issue of arrival time jitter between streaking laser and X-ray pulse, but compromises the achievable temporal resolution. Possible solutions to these remaining challenges for single-shot, full time-energy characterization of X-ray free-electron laser pulses are proposed in the outlook at the end of the review.

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Section: Measurement Resolutionmentioning

confidence: 99%

Ultrashort Free-Electron Laser X-ray Pulses

et al. 2017

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“…Therefore, different pathways competing to form a multiply charged state can be distinguished unambiguously, which is not possible by simple ion detection. In addition, photoelectron spectroscopy enables one to characterize the spectrum of each FEL shot, as demonstrated recently [17]. This capability is promising for a detailed investigation of the multiple ionization processes, under the present operations of FEL in the selfamplified spontaneous emission (SASE) scheme.…”

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confidence: 95%

Multiphoton Double Ionization of Ar in Intense Extreme Ultraviolet Laser Fields Studied by Shot-by-Shot Photoelectron Spectroscopy

et al. 2010

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Photoelectron spectroscopy has been performed to study the multiphoton double ionization of Ar in an intense extreme ultraviolet laser field (hν ∼ 21 eV, ∼ 5 TW/cm²), by using a free electron laser (FEL). Three distinct peaks identified in the observed photoelectron spectra clearly show that the double ionization proceeds sequentially via the formation of Ar(+): Ar+hν→Ar (+) + e⁻ and Ar²(+) + 2hν→Ar(+) + e⁻. Shot-by-shot recording of the photoelectron spectra allows simultaneous monitoring of FEL spectrum and the multiphoton process for each FEL pulse, revealing that the two-photon ionization from Ar(+) is significantly enhanced by intermediate resonances in Ar(+).

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“…In the soft x-ray range, time-of-flight spectroscopy on the photoemitted electrons [5] or ions [6] in a gas has been used to obtain emission spectra without interfering with an experiment downstream. However, in the hard x-ray range when using applicable gas pressures, the photoionization cross sections become too small for this method to work well.…”

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confidence: 99%

Single-shot analysis of hard x-ray laser radiation using a noninvasive grating spectrometer

et al. 2012

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We present a spectrometer setup based on grating dispersion for hard x-ray free-electron lasers. This setup consists of a focusing spectrometer grating and a charge-integrating microstrip detector. Measurement results acquired at Linac Coherent Light Source are presented, demonstrating noninvasive monitoring of single-shot spectra with a resolution of 2.0×10(-4) ±0.3×10(-4) at photon energy of 6 keV with more than 95% transmission of the main beam.

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Photoelectron spectroscopy as a non-invasive method to monitor SASE-FEL spectra

Cited by 20 publications

References 21 publications

Ultrashort Free-Electron Laser X-ray Pulses

Ultrashort Free-Electron Laser X-ray Pulses

Multiphoton Double Ionization of Ar in Intense Extreme Ultraviolet Laser Fields Studied by Shot-by-Shot Photoelectron Spectroscopy

Single-shot analysis of hard x-ray laser radiation using a noninvasive grating spectrometer

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