Circular dichroism measurements at an x-ray free-electron laser with polarization control

Journal Article · Mon Aug 15 00:00:00 EDT 2016 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4961470· OSTI ID:22597648

Hartmann, G.; Shevchuk, I.; Walter, P.; Viefhaus, J. ^[1]; Lindahl, A. O. ^[2]; Knie, A. ^[3]; Hartmann, N.; Lutman, A. A.; MacArthur, J. P.; Glownia, J. M.; Helml, W.; Huang, Z.; Marinelli, A.; Nuhn, H. -D.; Moeller, S.; Coffee, R. N.; Buck, J.; Galler, A.; Liu, J. ^[4]; others, and

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1. Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607 Hamburg (Germany)
2. PULSE at Stanford, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)
3. Institut für Physik, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel (Germany)
4. European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany)

A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a combined two-color, multi-photon experiment with polarization control, the degree of circular polarization of the Delta undulator has been determined. Towards this goal, an oriented electronic state in the continuum was created by non-resonant ionization of the O{sub 2} 1s core shell with circularly polarized FEL pulses at hν ≃ 700 eV. An also circularly polarized, highly intense UV laser pulse with hν ≃ 3.1 eV was temporally and spatially overlapped, causing the photoelectrons to redistribute into so-called sidebands that are energetically separated by the photon energy of the UV laser. By determining the circular dichroism of these redistributed electrons using angle resolving electron spectroscopy and modeling the results with the strong-field approximation, this scheme allows to unambiguously determine the absolute degree of circular polarization of any pulsed, ultraintense XUV or X-ray laser source.

• OSTI ID: 22597648
• Journal Information: Review of Scientific Instruments, Vol. 87, Issue 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
APPROXIMATIONS
COMPUTERIZED SIMULATION
DIAGNOSTIC TECHNIQUES
DICHROISM
ELECTRON SPECTROSCOPY
ELECTRONS
EXTREME ULTRAVIOLET RADIATION
FERMILAB ACCELERATOR
FREE ELECTRON LASERS
IONIZATION
LINEAR ACCELERATORS
MULTI-PHOTON PROCESSES
PHOTONS
POLARIZATION
PULSES
STANFORD LINEAR ACCELERATOR CENTER
WAVELENGTHS
WIGGLER MAGNETS
X RADIATION
X-RAY LASERS