The brightness and coherence of modern light sources is pushing the limits of X-ray beamline design. The open source Synchrotron Radiation Workshop (SRW) provides physical optics based algorithms for correctly simulating such beamlines.<sup>1</sup> We present new SRW capabilities to calculate source brightness and related quantites for undulators. The Sirepo cloud computing framework<sup>2, 3</sup> includes a browser-based GUI for SRW.<sup>4–6</sup> In addition to high-accuracy wavefront simulations, the Sirepo interface now supports analytical calculations for flux, photon beam size, divergence and photon brightness. We have included the effects of detuning from resonance and electron beam energy spread, which can be important in realistic operational conditions. We compare our results to features previously available in the Igor Pro interface to SRW, to analytical formulae available in the literature, and also to the results of simulated wavefront propagation. Differences between the various approaches are explained in detail, so that all the assumptions, conventions and ranges of validity can be better understood.
The paper presents an overview of the main functions and new application examples of the “Synchrotron Radiation Workshop” (SRW) code. SRW supports high-accuracy calculations of different types of synchrotron radiation, and simulations of propagation of fully-coherent radiation wavefronts, partially-coherent radiation from a finite-emittance electron beam of a storage ring source, and time-/frequency-dependent radiation pulses of a free-electron laser, through X-ray optical elements of a beamline. An extended library of physical-optics “propagators” for different types of reflective, refractive and diffractive X-ray optics with its typical imperfections, implemented in SRW, enable simulation of practically any X-ray beamline in a modern light source facility. The high accuracy of calculation methods used in SRW allows for multiple applications of this code, not only in the area of development of instruments and beamlines for new light source facilities, but also in areas such as electron beam diagnostics, commissioning and performance benchmarking of insertion devices and individual X-ray optical elements of beamlines. Applications of SRW in these areas, facilitating development and advanced commissioning of beamlines at the National Synchrotron Light Source II (NSLS-II), are described.
Synchrotron Radiation Workshop (SRW) is a powerful synchrotron radiation simulation tool and has been widely used at synchrotron facilities all over the world. During the last decade, many types of X-ray wavefront sensors have been developed and used. In this work, we present our recent effort on the development of at-wavelength metrology simulation based on SRW mainly focused on the Hartmann Wavefront Sensor (HWS). Various conditions have been studied to verify that the simulated HWS is performing as expected in terms of accuracy. This at-wavelength metrology simulation tool is then used to align KB mirrors by minimizing the wavefront aberrations. We will present our optimization process to perform an ‘in situ’ alignment using conditions as close as possible to the real experiments (KB mirrors with different levels of figure errors or different misalignment geometry).
We present the application of fully- and partially-coherent synchrotron radiation wavefront propagation simulation functions, implemented in the "Synchrotron Radiation Workshop" computer code, to create a ‘virtual beamline’ mimicking the Coherent Hard X-ray scattering beamline at NSLS-II. The beamline simulation includes all optical beamline components, such as the insertion device, mirror with metrology data, slits, double crystal monochromator and refractive focusing elements (compound refractive lenses and kinoform lenses). A feature of this beamline is the exploitation of X-ray beam coherence, boosted by the low-emittance NSLS-II storage-ring, for techniques such as X-ray Photon Correlation Spectroscopy or Coherent Diffraction Imaging. The key performance parameters are the degree of Xray beam coherence and photon flux, and the trade-off between them needs to guide the beamline settings for specific experimental requirements. Simulations of key performance parameters are compared to measurements obtained during beamline commissioning, and include the spectral flux of the undulator source, the degree of transverse coherence as well as focal spot sizes.
“Sirepo” is an open source cloud-based software framework which provides a convenient and user-friendly web-interface for scientific codes such as Synchrotron Radiation Workshop (SRW) running on a local machine or a remote server side. SRW is a physical optics code allowing to simulate the synchrotron radiation from various insertion devices (undulators and wigglers) and bending magnets. Another feature of SRW is a support of high-accuracy simulation of fully- and partially-coherent radiation propagation through X-ray optical beamlines, facilitated by so-called “Virtual Beamline” module. In the present work, we will discuss the most important features of Sirepo/SRW interface with emphasis on their use for commissioning of beamlines and simulation of experiments at National Synchrotron Light Source II. In particular, “Flux through Finite Aperture” and “Intensity” reports, visualizing results of the corresponding SRW calculations, are being routinely used for commissioning of undulators and X-ray optical elements. Material properties of crystals, compound refractive lenses, and some other optical elements can be dynamically obtained for the desired photon energy from the databases publicly available at Argonne National Lab and at Lawrence Berkeley Lab. In collaboration with the Center for Functional Nanomaterials (CFN) of BNL, a library of samples for coherent scattering experiments has been implemented in SRW and the corresponding Sample optical element was added to Sirepo. Electron microscope images of artificially created nanoscale samples can be uploaded to Sirepo to simulate scattering patterns created by synchrotron radiation in different experimental schemes that can be realized at beamlines.
High-accuracy physical optics calculation methods used in the “Synchrotron Radiation Workshop” (SRW) allow for multiple applications of this code in different areas, covering development, commissioning, diagnostics and operation of X-ray instruments at light source facilities. This presentation focuses on the application of the SRW code for the simulation of experiments at these facilities. The most complete and most detailed simulation of experiments with SRW is possible in the area of elastic coherent scattering, where the interaction of radiation with samples can be described with the same transmission-type “propagators” that are used for the simulation of fully- and partially-coherent radiation propagation through X-ray optical elements of beamlines. A complete “source-to-detector” simulation of such an experiment for a lithographic sample is described here together with comparisons of the simulated coherent scattering data with actual measurements results, obtained at the Coherent Hard X-ray (CHX) beamline of the National Synchrotron Light Source II (NSLS-II). Particular attention is paid to the analysis of visibility of speckles and intensity levels in the scattered radiation patterns at different degrees of coherence of the radiation entering the sample.