A5086465335- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Gyrotron and Vacuum Electronics Research
- Advancements in Photolithography Techniques
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle Detector Development and Performance
- Mass Spectrometry Techniques and Applications
- Advanced Electron Microscopy Techniques and Applications
- Terahertz technology and applications
- Photocathodes and Microchannel Plates
- Adrenal and Paraganglionic Tumors
- Laser-Matter Interactions and Applications
- Radioactive element chemistry and processing
- Laser-induced spectroscopy and plasma
- Photonic and Optical Devices
- Laser Design and Applications
- Image Processing Techniques and Applications
- Advanced Measurement and Metrology Techniques
- CCD and CMOS Imaging Sensors
Deutsches Elektronen-Synchrotron DESY
2007-2023
European Union
2013
Northern Illinois University
2012
Fermi National Accelerator Laboratory
2012
Universität Hamburg
2011
Daresbury Laboratory
2004
Technische Universität Berlin
1996-2002
Dublin City University
2000
FLASH, the Free-electron LASer in Hamburg, is a worldwide unique source for extremely bright ultra-short laser-like pulses tunable wide spectral range extreme ultraviolet and soft x-ray region (Ackermann et al 2007 Nat. Photonics 1 336–42). To fully exploit features of this new generation light sources, user facility with efficient radiation transport to experimental area novel online photon diagnostics capable characterizing parameters FLASH has been built. It serves broad community active...
The following topics are dealt with: TTF/FLASH in the XFEL context, general layout of facility, accelerator, undulators for SAES and spontaneous emission, photon beamlines scientific instruments, infrastructure auxiliary systems, commissioning operation, project management organization, cost time schedule. (HSI)
We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed gain (approximately 3000) and radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, intensity fluctuations, are all consistent with models for SASE FELs.
Experimental results are presented from vacuum-ultraviolet free-electron laser (FEL) operating in the self-amplified spontaneous emission (SASE) mode. The generation of ultrashort radiation pulses became possible due to specific tailoring bunch charge distribution. A complete characterization linear and nonlinear modes SASE FEL operation was performed. At saturation produces (30-100 fs FWHM) with a peak power GW level full transverse coherence. wavelength tuned range 95-105 nm.
Recording electric field evolution in single-shot with THz bandwidth is needed science including spectroscopy, plasmas, biology, chemistry, Free-Electron Lasers, accelerators, and material inspection. However, the potential application range depends on possibility to achieve sub-picosecond resolution over a long time window, which largely open problem for techniques. To solve this problem, we present new conceptual approach so-called spectral decoding technique, where chirped laser pulse...
In order to measure the photon flux of highly intense and extremely pulsed vacuum ultraviolet (VUV) extreme (EUV) radiation in absolute terms, we have developed a gas-monitor detector which is based on atomic photoionization rare gas at low particle density. The device indestructible almost transparent. By first pulse-resolved measurements VUV free-electron laser TESLA test facility Hamburg, peak power more than 100 MW was detected. Moreover, extended dynamic range allowed its accurate...
One of the most challenging tasks for extreme ultraviolet, soft and hard x-ray free-electron laser photon diagnostics is precise determination pulse duration, which typically in sub 100 fs range. Nine different methods, able to determine such ultrashort durations, were compared experimentally at FLASH, self-amplified spontaneous emission DESY Hamburg, order identify advantages disadvantages methods. Radiation pulses a wavelength 13.5 24.0 nm together with corresponding electron bunch...
The successful operation of X-ray free-electron lasers (FELs), like the Linac Coherent Light Source or Free-Electron Laser in Hamburg (FLASH), makes unprecedented research on matter at atomic length and ultrafast time scales possible. However, order to take advantage these unique light sources meet strict requirements many experiments photon science, FEL pulse durations need be known tunable. This can achieved by controlling driving electron beams, high-resolution longitudinal beam...
We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies impressing nonlinear correlations in longitudinal phase space using a superconducing radiofrequency linear accelerator operating at two frequencies and current-enhancing dispersive section. produced $\sim 700$-MeV have peak currents order kilo-Amp\`ere. Data taken for various settings demonstrate versatility method particular its ability to produce profiles that...
The decay channels of the $\mathrm{Ar}{2s}^{\ensuremath{-}1}$ and ${2p}^{\ensuremath{-}1}$ $\mathrm{Kr}{3p}^{\ensuremath{-}1}$ ${3d}^{\ensuremath{-}1}$ electronic hole states have been investigated by means photoelectron-photoion coincidence measurements following innershell ionization using synchrotron radiation. With method final ion-charge resolving electron spectroscopy it has become possible to disentangle different contributions spectrum determine probabilities...
The $3p$ photoelectron spectra of Cr, Mn, Fe, and Co atoms have been studied experimentally theoretically. $3p$-$3d$ interaction in the final ionic state gives rise to an $\mathrm{LS}$ multiplet structure spanning a binding-energy range around 20 eV. prominent high-spin components at low binding energies contrast with broad weak low-spin high energies. Term-dependent lifetime broadening by super-Coster-Kronig decays is main cause almost complete suppression latter lines. corresponding metals...
The photoelectron-photoion coincidence method is shown to be very successful for the quantitative investigation of ratio radiative nonradiative transitions and single double Auger transitions. These decay probabilities are important parameters analytical methods as well theoretical descriptions. demonstrated neon $1s$ decay. Especially fluorescence yield process have been determined both experimentally theoretically.
Electron-ion coincidence spectroscopy of energy-analyzed electrons and charge-separated ions is used to investigate complex decay processes atoms after inner-shell photoionization with monochromatized synchrotron radiation. Improvements in the experimental technique allow a complete electron spectrum resolved into different contributions final ion-charge states be measured. This method resolving demonstrated by example xenon for region...
A high-resolution $4d$ photoelectron spectrum of Eu has been measured. The reveals a rich structure reflecting multiplet splitting due to $4d\ensuremath{-}4f,$ $4f\ensuremath{-}4f,$ and spin-orbit interaction. In order interpret the complex ${4d}^{\ensuremath{-}1}$ structure, calculations in intermediate coupling scheme were performed taking into account term-dependent lifetime width each state. strong influence both $4d\ensuremath{-}4f$ exchange interaction broadening on shape is...
Electron spectroscopy in direct $4d$ photoionization of free ${\mathrm{Xe}}^{+}$ ions has been realized for the first time, applying various timing and coincidence techniques to suppress monitor on line strong fluctuating background. The ionization energies ${4d}_{5/2}$ ${4d}_{3/2}$ electrons ${\mathrm{Xe}}^{+}({5p}^{5}^{2}P_{3/2})$ ${\mathrm{Xe}}^{+}({5p}^{5}^{2}P_{1/2})$ were determined compared calculated RHF(CI) values corresponding results neutral $\mathrm{Xe}({5p}^{6}^{1}S_{0})$ atoms...
Using monochromatized synchrotron radiation and atomic beam technique the photoion spectra of Fe, Co, Ni in region 3p resonances were measured. For interpretation photoionization cross sections calculated, taking into account strong interconfiguration mixing type (3d,4s${)}^{\mathit{N}}$ thermal population different fine-structure levels ground states according to temperature about 1800 K for evaporation metals. The calculations performed framework overlapping interacting with many continua....
The 3p photoelectron spectra of atomic Fe and Cu, the outer-shell satellites have been investigated. complex multiline structure has resolved using high-resolution electron spectroscopy. thresholds direct photoionization determined are compared with experimental results from photoabsorption measurements Auger spectra, multiplet structures calculated taking into account intershell configuration interaction. stepwise decay highly excited states verified by detection satellite lines binding...