A new graphic environment to drive X-ray optics simulation packages such as SHADOW and SRW is proposed. The
aim is to simulate a virtual experiment, including the description of the electron beam and simulate the emitted
radiation, the optics, the scattering by the sample and radiation detection. Python is chosen as common interaction
language. The ingredients of the new application, a glossary of variables for optical component, the selection of
visualization tools, and the integration of all these components in a high level workflow environment built on Orange
are presented.
A “source-to-sample” wavefront propagation analysis of the Electron Spectro-Microscopy (ESM) UV / soft X-ray
beamline, which is under construction at the National Synchrotron Light Source II (NSLS-II) in the Brookhaven
National Laboratory, has been conducted. All elements of the beamline - insertion device, mirrors, variable-line-spacing
gratings and slits - are included in the simulations. Radiation intensity distributions at the sample position are displayed
for representative photon energies in the UV range (20 - 100 eV) where diffraction effects are strong. The finite
acceptance of the refocusing mirrors is the dominating factor limiting the spatial resolution at the sample (by ~3 μm at
20 eV). Absolute estimates of the radiation flux and energy resolution at the sample are also obtained from the
electromagnetic calculations. The analysis of the propagated UV range undulator radiation at different deflection
parameter values demonstrates that within the beamline angular acceptance a slightly “red-shifted” radiation provides
higher flux at the sample and better energy resolution compared to the on-axis resonant radiation of the fundamental
harmonic.
We report on the implications of the design of a Soft Matter Interfaces beamline, a long energy range canted in-vacuum
undulator (IVU) beamline at National Synchrotron Light Source II, based on comparison of geometrical ray-tracing and
partially coherent x-ray wavefront propagation simulation software packages, namely, SHADOW and Synchrotron
Radiation Workshop (SRW). For SHADOW, we employed an SRW-generated source file which simulated spectralangular
distribution and apparent source characteristics of radiation produced by a 2.8 m long IVU with a 23 mm period
and allowed us to realistically estimate the beam intensity at the sample positions. We highlight the necessity to use
realistic mirror surface profiles with expected slope errors as opposed to “standard” built-in SHADOW surface error
options. The beamline performances at three different x-ray photon energies: 20358 eV, 10778 eV, and 2101 eV, under
different focusing conditions, have been studied. We compare beamline simulations performed with both software
packages. In particular, we stress that the neglect of wavefront diffraction effects in geometrical ray-tracing approach
results in significant discrepancies in beam spot size and beam shape, the correct assessments of which are crucial in
determining the future performance of an instrument.
We present the conceptual design of a dispersive X-ray Absorption Fine Structure (XAFS) beamline for MIRRORCLE,
a new compact laboratory X-ray source. This machine accelerates electrons up to 1,4,6 or 20MeV
(depending upon the model) in a ring and produces X-rays when the electrons collide onto a thin target. The
radiation emitted has a white spectrum due to both synchrotron and bremsstrahlung emission. A substantial
part of the electrons are recovered after collisions, and the emitted light has high flux, wide energy spectrum
and a large angular dispersion.
We have opted for a simple beamline design using a collimator, slits, a curved crystal, the sample environment
and a CCD. The beamline parameters (position of the mirror, ray of curvature, slit aperture, reflecting angle, etc.)
have been optimized by defining and improving a figure of merit. This optimization allows for room constraints
(distances among elements), mechanical constraints (minimum curvature radii available) and optical constraints.
Further ray tracing simulations using SHADOW3 have been performed to check all the theoretical results, refine
the final parameters, quantitative flux calculations and for simulating the image on the CCD camera.
We developed the third version of SHADOW, a ray tracing software widely used to design optical system in the synchrotron world. SHADOW3 is written in Fortran 2003 and follows the new computer engineering standards. The users can always execute the program in the traditional file oriented approach. Moreover, advanced users can create personalized scripts, macros and executables using the new Application Programming Interface SHADOW3-API. It also allows binding of SHADOW3 with several popular programming languages
such as C, C++, python and IDL. We describe the SHADOW3 API structure, and illustrate its use with some examples.
We analyze the possibilities of running SHADOW3 in parallel machines under different environments. A
version using the Open Message Parsing Interface has been implemented. A SHADOW3 postprocessor has been
accelerated with the use Graphics Processing Units. This will open new possibilities to extend the already very
popular ray tracing tool to applications simulating 2D and 3D experiments (like imaging, tomography)
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