ESRF Upgrade Program Research Articles

New data analysis for BioSAXS at the ESRF.

The second phase of the ESRF upgrade program did not only provide a new storage ring (Extremely Brilliant Source, EBS) but also allowed several beamlines to be refurbished. The BioSAXS beamline (located on port BM29) was upgraded with a new wiggler source and a larger detector. All analysis software has been rewritten to cope with the increased data flux and continues to provide beamline users with reduced and pre-processed data in real time. This article describes FreeSAS, an open-source collection of various small-angle scattering analysis algorithms needed to reduce and analyze BioSAXS data, and Dahu, the tool used to interface data analysis with beamline control. It further presents the data-processing pipelines for the different data acquisitions modes of the beamline, using either a sample changer for individual homogeneous samples or an inline size-exclusion chromatography setup.

New challenges in beamline instrumentation for theESRF Upgrade Programme Phase II.

Although beamline instrumentation is by nature driven by science, some recent examples serve as reminders that new technologies also enable new science. Indeed, exploiting the full scientific potential of forthcoming new storage rings with unprecedented source characteristics will, in many cases, require the development and implementation of novel instrumentation. In comparison with present synchrotron radiation facilities, the majority of beamlines should reap immediate performance benefits from the improved source emittance, principally through increased flux and/or horizontal beam size reduction at the sample. Instrumentation will have to develop along similar quantitative and qualitative trends. More speculative and more challenging is anticipating instrumentation that will be required by the new science made possible thanks to the unique coherence properties of diffraction-limited storage rings (DLSRs). ESRF has recently carried out a detailed feasibility study for a new ultra-low-emittance 6 GeV hybrid multibend storage ring, identified as ESRF Upgrade Programme Phase II. Although its performance is not expected to be equivalent to a DLSR source, the successful implementation of the ESRF Phase II project has to address scientific instrumentation issues that are also common to DLSRs. This article aims at providing a comprehensive review of some of the challenges encountered by the ESRF, in the context of the preparation of PhaseII of its upgrade programme.

Exploiting coherence for real-time studies by single-bunch imaging.

First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding bunch length is 140 ps FWHM). Hard X-ray imaging with absorption contrast as well as phase contrast in combination with large propagation distances is demonstrated using spatial samplings of 11 µm and 35 µm pixel size. The images acquired allow one to track crack propagation in a bursting piece of glass, breaking of an electrical fuse as well as cell wall rupture in an aqueous foam. Future developments and their potential in the frame of the proposed Phase II of the ESRF Upgrade Program are discussed.

Upgraded ESRF BM29 beamline for SAXS on macromolecules in solution

Small-angle X-ray scattering (SAXS) measurements of proteins in solution are becoming increasingly popular with biochemists and structural biologists owing to the presence of dedicated high-throughput beamlines at synchrotron sources. As part of the ESRF Upgrade program a dedicated instrument for performing SAXS from biological macromolecules in solution (BioSAXS) has been installed at the renovated BM29 location. The optics hutch has been equipped with new optical components of which the two principal elements are a fixed-exit double multilayer monochromator and a 1.1 m-long toroidal mirror. These new dedicated optics give improved beam characteristics (compared with the previous set-up on ID14-3) regarding the energy tunability, flux and focusing at the detector plane leading to reduced parasitic scattering and an extended s-range. User experiments on the beamline have been successfully carried out since June 2012. A description of the new BioSAXS beamline and the set-up characteristics are presented together with examples of obtained data.

New generation mirror systems for the ESRF upgrade beamlines

The construction of new beamlines defined in the ESRF upgrade program, requires high performance optics, for which thermal and mechanical stability will be of the utmost importance. Solutions for optimizing drifts and thermal gradients, as well as vibration free positioning have been analysed. This has lead to new opto-mechanical engineering able to implement generic solutions for the optics, such as new architecture for flat or bent mirrors, multilayer monochromators, and a new generation hexapod for toroidal mirrors. Vertical incidence fine tuning within 200 nrad, as well as horizontal reflection resolution in the range of 50 nrad, has lead to the development of different movers and positioning mechanisms. A review is presented, considering the different design validation stages and laboratory commissioning and showing performance achieved on the very first upgrade beamlines.

New challenges in ray tracing simulations of X-ray optics

The construction of new synchrotron sources and the refurbishment and upgrade of existing ones has boosted in the last years the interest in X-ray optics simulations for beamline design and optimization. In the last years we conducted a full renewal of the well established SHADOW ray tracing code, ending with a modular version SHADOW3 interfaced to multiple programming languages (C, C++, IDL, Python). Some of the new features of SHADOW3 are presented. From the physics point of view, SHADOW3 has been upgraded for dealing with lens systems. X-ray partial coherence applications demand an extension of traditional ray tracing methods into a hybrid ray-tracing wave-optics approach. The software development is essential for fulfilling the requests of the ESRF Upgrade Programme, and some examples of calculations are also presented.

UHV Superconducting Magnet System for Soft X-ray MCD Experiments

In the framework of the ESRF upgrade program, the soft X-ray beamline UPBL7 will replace the current beamline ID08. The new beamline will be installed on port ID32 and will be equipped with a superconducting magnet system dedicated to study the electronic and magnetic properties of matter using soft X-rays from 300 up to 1500 eV. The magnet system comprises two nested UHV cold bore split-coil magnets of ±9T along the X-ray beam and ± 4T perpendicular to the X-ray beam and a variable temperature insert with a temperature range of 1.5 to 400 K. The VTI wiring will include possibilities to measure total electron yield, sample transport properties or the application of an electric field. The system will be further equipped with a UHV sample preparation facility allowing in-situ application of surface science techniques.

Thermal stability optimization of the ESRF nano hutch

The ESRF upgrade programme includes a number of extended beamlines in which instrumentation stability, be it mechanical or thermal, will be of utmost importance. Significant efforts are being made at every stage of design to increase stiffness and minimize thermal drift, but a thermally stable environment would greatly facilitate instrument conception and enhance overall performance. A numerical model of the most stable existing ESRF experimental hutch is detailed. With the aim to enhance thermal performance of future ‘nano hutches’, several optimization studies, both spatial and transient, have been performed on this model. Results from these studies and associated recommendations for future nano hutch design improvements are presented.

The ESRF upgrade programme

The ESRF upgrade programme