1,142 research outputs found
Design study of time-preserving grating monochromators for ultrashort pulses in the extreme-ultraviolet and soft X-rays
The design of grating-based instruments to handle and condition coherent ultrafast
pulses in the extreme-ultraviolet is discussed. The main application of such instruments is the
monochromatization of high-order laser harmonics and free-electron-laser pulses in the femtosecond
time scale. Broad-band monochromators require the use of diffraction gratings at grazing incidence.
A grating can be used for the spectral selection of ultrashort pulses without altering the pulse duration
in a significant way, provided that the number of illuminated grooves is equal to the resolution.
We discuss here the design conditions to be fulfilled by a grating monochromator that does not
increase the pulse duration significantly longer than the Fourier limit
Notes about collision monochromatization in colliders
The manuscript describes several monochromatization schemes starting from
A.~Renieri \cite{ref:Renieri} proposal for head-on collisions based on
correlation between particles transverse position and energy deviation. We
briefly explain initial proposal and expand it for crossing angle collisions.
Then we discuss new monochromatization scheme for crossing angle collisions
based on correlation between particles longitudinal position and energy
deviation
Novel opportunities for sub-meV inelastic X-ray scattering at high-repetition rate self-seeded X-ray free-electron lasers
Inelastic X-ray scattering (IXS) is an important tool for studies of
equilibrium dynamics in condensed matter. A new spectrometer recently proposed
for ultra-high-resolution IXS (UHRIX) has achieved 0.6~meV and 0.25~nm
spectral and momentum transfer resolutions, respectively. However, further
improvements down to 0.1~meV and 0.02~nm are required to close the gap
in energy-momentum space between high and low frequency probes. We show that
this goal can be achieved by further optimizing the X-ray optics and by
increasing the spectral flux of the incident X-ray pulses. UHRIX performs best
at energies from 5 to 10 keV, where a combination of self-seeding and undulator
tapering at the SASE-2 beamline of the European XFEL promises up to a
hundred-fold increase in average spectral flux compared with nominal SASE
pulses at saturation, or three orders of magnitude more than possible with
storage-ring based radiation sources. Wave-optics propagation shows that about
~ph/s in a -eV bandwidth can be achieved on the
sample. This will provide unique new possibilities for dynamics studies by IXS.Comment: 17 pages, 14 figure
Low energy activation analysis for geochemical exploration
Low energy activation analysis for geochemical exploratio
Extension of self-seeding scheme with single crystal monochromator to lower energy < 5 keV as a way to generate multi-TW scale pulses at the European XFEL
We propose a use of the self-seeding scheme with single crystal monochromator
to produce high power, fully-coherent pulses for applications at a dedicated
bio-imaging beamline at the European X-ray FEL in the photon energy range
between 3.5 keV and 5 keV. We exploit the C(111) Bragg reflection
(pi-polarization) in diamond crystals with a thickness of 0.1 mm, and we show
that, by tapering the 40 cells of the SASE3 type undulator the FEL power can
reach up to 2 TW in the entire photon energy range. The present design assumes
the use of a nominal electron bunch with charge 0.1 nC at nominal electron beam
energy 17.5 GeV. The main application of the scheme proposed in this work is
for single shot imaging of individual protein molecules
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