Photon beamlines and diagnostics at LCLS

Moeller, Stefan; Arthur, John R.; Brachmann, A.; Coffee, R.; Decker, F.‐J.; Ding, Yuantao; Dowell, D.H.; Edstrom, S.; Emma, P.; Feng, Yiping; Fisher, A.; Frisch, J.; Galayda, J.; Gilevich, S.; Hastings, J. B.; Hays, G.; Hering, Ph.; Huang, Zhirong; Iverson, R.; Krzywiński, J.; Lewis, Samantha M.; Loos, H.; Messerschmidt, Marc; Miahnahri, Alan; Nuhn, H.‐D.; Ratner, Daniel; Rzepiela, Jeffrey A.; Schultz, D.; Smith, T.; Stefan, P.M.; Tompkins, Harland G.; Turner, J.; Welch, J.; White, Bill; Wu, Juhao; Yocky, G.; Bionta, R.; Ables, E.; Abraham, Baxter; Gardener, C.; Fong, K.; Friedrich, S.; Hau‐Riege, Stefan P.; Kishiyama, K.; McCarville, T.; McMahon, Donn H.; McKernan, M. A.; Ott, L.; Pivovaroff, M. J.; Robinson, Jeffrey C.; Ryutov, D. D.; Shen, S.; Soufli, Régina; Pile, G.

doi:10.1016/j.nima.2010.10.125

Cited by 63 publications

(32 citation statements)

References 12 publications

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“…The experiment was carried out using the SXR experimental station [16] of the LCLS facility [5,6]. The SASE (Self Amplified Spontaneous Emission) FEL X-ray source was operated with the electron bunch charge 250 pC and 13 undulator segments tunable to deliver X-ray photons with energies between 800 eV and 2000 eV (λ from 1.55 nm to 0.62 nm).…”

Section: Methodsmentioning

confidence: 99%

X-ray laser-induced ablation of lead compounds

Hájková¹,

Juha²,

Boháček³

et al. 2011

SPIE Proceedings

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The recent commissioning of a X-ray free-electron laser triggered an extensive research in the area of X-ray ablation of high-Z, high-density materials. Such compounds should be used to shorten an effective attenuation length for obtaining clean ablation imprints required for the focused beam analysis. Compounds of lead (Z=82) represent the materials of first choice. In this contribution, single-shot ablation thresholds are reported for PbWO 4 and PbI 2 exposed to ultra-short pulses of extreme ultraviolet radiation and X-rays at FLASH and LCLS facilities, respectively. Interestingly, the threshold reaches only 0.11 J/cm 2 at 1.55 nm in lead tungstate although a value of 0.4 J/cm 2 is expected according to the wavelength dependence of an attenuation length and the threshold value determined in the XUV spectral region, i.e., 79 mJ/cm 2 at a FEL wavelength of 13.5 nm. Mechanisms of ablation processes are discussed to explain this discrepancy. Lead iodide shows at 1.55 nm significantly lower ablation threshold than tungstate although an attenuation length of the radiation is in both materials quite the same. Lower thermal and radiation stability of PbI 2 is responsible for this finding.

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Section: Methodsmentioning

confidence: 99%

X-ray laser-induced ablation of lead compounds

Hájková¹,

Juha²,

Boháček³

et al. 2011

SPIE Proceedings

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“…The reconstruction is done shot by shot and the incoming electron energy jitter has to be subtracted to determine the absolute power. In a simple way, the absolute power scale of the reconstructed X-ray profile can also be calibrated against the total X-ray pulse energy, as measured simultaneously at a calibrated gas detector 38 . In this way, the electron beam energy jitter issue can be ignored during data processing.…”

Section: Article Nature Communications | Doi: 101038/ncomms4762mentioning

confidence: 99%

Few-femtosecond time-resolved measurements of X-ray free-electron lasers

et al. 2014

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X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1 fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100 GW.

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“…(1) and (2). The values of σ and μ are determined over the spatial frequency intervals, specific for the optic's application.…”

Section: Limitations Of Current Specification Of Mirror Quality As Apmentioning

confidence: 99%

Specification of x-ray mirrors in terms of system performance: a new twist to an old plot

2014

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Abstract. In the early 1990s, Church and Takacs pointed out that the specification of surface figure and finish of x-ray mirrors must be based on their performance in the beamline optical system. We demonstrate the limitations of specification, characterization, and performance evaluation based on conventional statistical approaches, including root-mean-square roughness and residual slope variation, evaluated over spatial frequency bandwidths that are system specific, and a more refined description of the surface morphology based on the power spectral density distribution. We show that these limitations are fatal, especially in the case of highly collimated coherent x-ray beams, like beams from x-ray free electron lasers (XFELs). The limitations arise due to the deterministic character of the surface profile data for a definite mirror, while the specific correlation properties of the surface are essential for the performance of the entire x-ray optical system. As a possible way to overcome the problem, we treat a method, suggested by Yashchuk and Yashchuk in 2012, based on an autoregressive moving average modeling of the slope measurements with a limited number of parameters. The effectiveness of the approach is demonstrated with an example specific to the x-ray optical systems under design at the European XFEL. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Photon beamlines and diagnostics at LCLS

Cited by 63 publications

References 12 publications

X-ray laser-induced ablation of lead compounds

X-ray laser-induced ablation of lead compounds

Few-femtosecond time-resolved measurements of X-ray free-electron lasers

Specification of x-ray mirrors in terms of system performance: a new twist to an old plot

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