Beamline Operation Research Articles

Shielding calculations for the design of new beamlines at ALBA synchrotron

ALBA is a Spanish synchrotron facility generating intense beams of synchrotron radiation from a 3 GeV electron accelerator. At ALBA Synchrotron, electrons are first accelerated in a 110 MeV linear accelerator and then injected in Booster ring which increases the energy up to 3 GeV. Finally, the electron beam is stored in a synchrotron Storage Ring with a current up to 400 mA emitting intense beam of synchrotron radiation. Both the Booster and the Storage Ring are located inside the same concrete building, the Tunnel, while the LINAC is located in a separated concrete building, the Bunker. Outside the Tunnel, and tangentially to the Storage Ring, are located the experimental research laboratories, the Beamlines, where scientists receive synchrotron light for a wide variety of experiments. At present ALBA has 8 Beamlines installed, 3 Beamline under construction, and 1 Beamlines in the design stage.This paper details the design of the shielding elements of the new Beamlines under construction called LOREA, NOTOS and XAIRA. The first one is a soft X-ray and the other two are hard X-ray Beamlines. Shielding calculations are performed using FLUKA Monte Carlo code and aim at quantifying the total dose rate produced by the different sources of radiation at the Beamlines in operation. In particular, it details the dose generated by the gas bremsstrahlung radiation resulting from the interaction of the 3 GeV electron beam with the residual gas of the storage ring vacuum chamber and compares it to the dose rate generated by the insertion device radiation flux. The objective of the FLUKA simulations performed in this work is to establish the requirements for all the Beamline shielding elements to ensure a public dose (dose rate lower than 0.5 μSv/h) outside the shielding during Beamline operation. Results from the simulations set the general requirements for all the Beamline shielding elements, from a radiation protection point of view.

Beamline operating software B4 and automated crystallography suite at the Berkeley Center for Structural Biology

Beamline operating software <i>B4</i> and automated crystallography suite at the Berkeley Center for Structural Biology

Influence of optics vibration on synchrotron beam coherence.

Vibration of optics is one of the major limiting factors of the performance of state-of-the-art beamlines at low-emittance synchrotron facilities. We present a theoretical model with experimental data describing vibration-induced effects on x-ray beam coherence. Owing to the incoherent nature of vibration, the decrease in the beam spatial coherence perturbed by optics vibrations can be characterized by modeling the effective source profile of the vibrating beam. The measurements were carried out by using grating interferometry and a refractive lens with controlled vibration as test optics. The experimental results confirm the model and reveal the dependency of the measured beam spatial coherence on the acquisition time. The proposed method can be used to identify the eigenfrequency of the optical system as well as to optimize beamline operation and experimental conditions for coherence-related techniques.

A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate.

Time- and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivity. The design and operation of the XUV beamline, pump-probe setup, and ultra-high vacuum endstation are described in detail. By characterizing the effect of space-charge broadening, we determine an ultimate source-limited energy resolution of 60 meV, with typically 80-100 meV obtained at 1-2 × 1010 photons/s probe flux on the sample. The instrument capabilities are demonstrated via both equilibrium and time-resolved ARPES studies of transition-metal dichalcogenides. The 50-kHz repetition rate enables sensitive measurements of quasiparticles at low excitation fluences in semiconducting MoSe2, with an instrumental time resolution of 65 fs. Moreover, photo-induced phase transitions can be driven with the available pump fluence, as shown by charge density wave melting in 1T-TiSe2. The high repetition-rate setup thus provides a versatile platform for sensitive XUV trARPES, from quenching of electronic phases down to the perturbative limit.

Pseudo-single-bunch mode for a 100 MHz storage ring serving soft X-ray timing experiments

At many storage rings for synchrotron light production there is demand for serving both high-flux and timing users simultaneously. Today this is most commonly achieved by operating inhomogeneous fill patterns, but this is not preferable for rings that employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. For these rings, inhomogeneous fill patterns could severely reduce the effect of the harmonic cavities. It is therefore of interest to develop methods to serve high-flux and timing users simultaneously without requiring gaps in the fill pattern. One such method is pseudo-single-bunch (PSB), where one bunch in the bunch train is kicked onto another orbit by a fast stripline kicker. The light emitted from the kicked bunch can then be separated by an aperture in the beamline. Due to recent developments in fast kicker design, PSB operation in multibunch mode is within reach for rings that operate with a 100 MHz RF system, such as the MAX IV and Solaris storage rings. This paper describes machine requirements and resulting performance for such a mode at the MAX IV 1.5 GeV storage ring. A solution for serving all beamlines is discussed as well as the consequences of beamline design and operation in the soft X-ray energy range.

NE-CAT: Crystallography Beamlines for Challenging Structural Biology Research

The NorthEastern Collaborative Access Team (NE-CAT) focuses on the design and operation of synchrotron X-ray beamlines for the solution of technically challenging structural biology problems and provides an important resource for the national and international research community. Currently, NE-CAT operates two undulator beamlines: a 6 - 22 keV tunable energy beamline (24-ID-C) and a 12.662 keV single energy beamline (24-ID-E). Both beamlines are equipped with state-of-the-art instrumentation. MD2 microdiffractometers installed at both beamlines provide very clean beams down to 5 microns in diameter and are capable of visualizing micron-sized crystals. Large area pixel array detectors (Pilatus6M and Eiger16M) provide fast noiseless data collection and make possible it to resolve large unit cells. Both beamlines are equipped with custom-built ALS-style robotic sample automounters with dewars capable of holding 14 pucks. Our locally developed software suite RAPD provides data collection strategies, quasi-real time data integration, scaling and simple automated MR/SAD pipeline through a 384-core compute cluster. Towards improving the diffraction from low resolution crystals, NE-CAT has installed humidity controlled device, HC1 in the 24ID-E hutch. Users of the beamlines are supported 24/7 by experienced resident crystallographers. Funding for NE-CAT is provided through a P41 grant from the NIGMS and from the NE-CAT member institutions.

Characterization of Carbon-Contaminated B4C-Coated Optics after Chemically Selective Cleaning with Low-Pressure RF Plasma

Boron carbide (B4C) is one of the few materials that is expected to be most resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at light source facilities, B4C-coated optics are subject to ubiquitous carbon contaminations. Carbon contaminations represent a serious issue for the operation of FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B4C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the low-pressure RF plasma cleaning of carbon contaminated B4C test samples via inductively coupled O2/Ar, H2/Ar, and pure O2 RF plasma produced following previous studies using the same ibss GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B4C optical coating before and after the plasma cleaning are reported. We conclude that among the above plasma processes only plasma based on pure O2 feedstock gas exhibits the required chemical selectivity for maintaining the integrity of the B4C optical coatings.

XDS: a flexible beamline for X-ray diffraction and spectroscopy at the Brazilian synchrotron.

The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage-ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X-ray spectrum (above ∼10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi-purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X-ray absorption spectroscopy at energies above 18 keV and high-resolution diffraction experiments. More recently, new setups and photon-hungry experiments such as total X-ray scattering, X-ray diffraction under high pressures, resonant X-ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.

Speckle-based at-wavelength metrology of X-ray mirrors with super accuracy

X-ray active mirrors, such as bimorph and mechanically bendable mirrors, are increasingly being used on beamlines at modern synchrotron source facilities to generate either focused or "tophat" beams. As well as optical tests in the metrology lab, it is becoming increasingly important to optimise and characterise active optics under actual beamline operating conditions. Recently developed X-ray speckle-based at-wavelength metrology technique has shown great potential. The technique has been established and further developed at the Diamond Light Source and is increasingly being used to optimise active mirrors. Details of the X-ray speckle-based at-wavelength metrology technique and an example of its applicability in characterising and optimising a micro-focusing bimorph X-ray mirror are presented. Importantly, an unprecedented angular sensitivity in the range of two nanoradians for measuring the slope error of an optical surface has been demonstrated. Such a super precision metrology technique will be beneficial to the manufacturers of polished mirrors and also in optimization of beam shaping during experiments.

In-situ compact 3He neutron spin polarizer based on a magneto-static cavity with built-in NMR coils

A polarized 3He neutron polarizer for in-situ neutron beam line operation was developed based on a compact magneto-static cavity with a dimension of 280×270×300 mm3 and a fiber-coupled VBG (Volume Bragg Grating) diode laser with a narrow spectral bandwidth of 25 GHz. Built-in NMR coils of the neutron spin polarizer designed for NMR signal measurements were described in detail and their performances were tested for monitoring the progress of in-situ 3He polarization.

Image guidance protocol for synchrotron microbeam radiation therapy

The protocol for image-guided microbeam radiotherapy (MRT) developed for the Australian Synchrotron's Imaging and Medical Beamline (IMBL) is described. The protocol has been designed for the small-animal MRT station of IMBL to enable future preclinical trials on rodents. The image guidance procedure allows for low-dose monochromatic imaging at 50 keV and subsequent semi-automated sample alignment in 3D with sub-100 µm accuracy. Following the alignment, a beamline operation mode change is performed and the relevant beamline components are automatically aligned for the treatment (pink) beam to be delivered on the sample. Here, the small-animal MRT station, the parameters and procedures for the image guidance protocol, as well as the experimental imaging results using phantoms are described. Furthermore, the experimental validation of the protocol using 3D PRESAGE(®) dosimeters is reported. It is demonstrated that the sample alignment is maintained after the mode change and the treatment can be delivered within the same spatial accuracy of 100 µm. The results indicate that the proposed approach is viable for preclinical trials of small-animal MRT.

Beamline P02.1 at PETRA III for high-resolution and high-energy powder diffraction.

Powder X-ray diffraction techniques largely benefit from the superior beam quality provided by high-brilliance synchrotron light sources in terms of photon flux and angular resolution. The High Resolution Powder Diffraction Beamline P02.1 at the storage ring PETRA III (DESY, Hamburg, Germany) combines these strengths with the power of high-energy X-rays for materials research. The beamline is operated at a fixed photon energy of 60 keV (0.207 Å wavelength). A high-resolution monochromator generates the highly collimated X-ray beam of narrow energy bandwidth. Classic crystal structure determination in reciprocal space at standard and non-ambient conditions are an essential part of the scientific scope as well as total scattering analysis using the real space information of the pair distribution function. Both methods are complemented by in situ capabilities with time-resolution in the sub-second regime owing to the high beam intensity and the advanced detector technology for high-energy X-rays. P02.1's efficiency in solving chemical and crystallographic problems is illustrated by presenting key experiments that were carried out within these fields during the early stage of beamline operation.

NE-CAT Crystallography Beamlines for Challenging Structural Biology Research

The NorthEastern Collaborative Access Team (NE-CAT) focuses on the design and operation of synchrotron X-ray beamlines for the solution of technically challenging structural biology problems and provides an important resource for the national and international research community. Currently NE-CAT operates two undulator beamlines: 24ID-C - tunable in the energy range from 6 to 22keV and 24ID-E - not-tunable, but optimized for Se SAD experiments. Both beamlines are equipped with state-of-the-art instrumentation. MD2 microdiffractometers installed at both beamlines provide very clean beams down to 5 microns in diameter and are capable of visualizing micron-sized crystals. Large area detectors (ADSC Quantum 315 at 24ID-E beamline and Pilatus-6MF at 24ID-C beamline), not only provide the best diffraction data, but also make possible to resolve large unit cells. Both beamlines are equipped with ALS style automatic sample mounters. Locally developed software suite RAPD provides data collection strategies, quasi-real time data integration and scaling and simple automated MR/SAD pipeline through 384 core computing cluster. Users of the beamlines are supported by experienced resident crystallographers. To meet the needs of technically challenging crystallographic projects, cutting-edge hardware and software ideas are implemented. A summary of beamline capabilities, technology, scientific highlights and details of availability will be presented. Funding for NE-CAT is provided through P41 grant from the NIGMS and from the NE-CAT member institutions.

A comprehensive facility for EXAFS measurements at the INDUS-2 synchrotron source at RRCAT, Indore, India

The EXAFS technique, which deals with fine structure oscillations observed in the X-ray absorption spectrum of an element from 50 eV to ~700 eV above its absorption edge, gives precise information regarding the short range order and local structure around the particular atomic species in the material. With the advent of modern bright synchrotron radiation sources, EXAFS has emerged to be the most powerful local structure determination technique, which can be applied to any type of material viz. amorphous, polycrystalline, polymers, surfaces and solutions etc. Over the last few years a comprehensive facility for carrying out EXAFS measurements with synchrotron radiation over variety of samples has been developed at the 2.5 GeV, Synchrotron Radiation Source (INDUS-2) at RRCAT, Indore, India. The facility consists of two operational beamlines viz., the energy dispersive EXAFS beamline (BL-08) and the Energy Scanning EXAFS beamline (BL-09).

A low-background-intensity focusing small-angle X-ray scattering undulator beamline

The SAXS/WAXS beamline at the Australian Synchrotron is an advanced and flexible undulator X-ray scattering beamline used for small- and wide-angle X-ray scattering analysis on a wide variety of solids, fluids and surfaces across a diverse range of research and development fields. The beamline has numerous features that minimize the intensity of the instrument background, provide automated stable optics, and allow accurate analysis of very weakly scattering samples. The geometric and intensity requirements of a three-slit collimation system are described in detail for conventional metal and single-crystal germanium slits. Straightforward ray tracing and simple linear projections describe the observed direct beam as well as parasitic background scattering geometry of the beamline at its longest camera length, providing a methodology for the design and operation of similar beamlines. As an aid to instrument design, the limit of background intensity determined by the intensity incident on single-crystal germanium guard slit edges and itsqdependence was quantified at 11 keV. Details of the beamline's implementation, underlying optical concept and measured performance are given.

At-wavelength Metrology of X-ray Optics at Diamond Light Source

Modern third-generation synchrotron radiation sources provide coherent and extremely bright X-ray beams, but the performance of the optics employed on the beamlines is critical for the X-rays' successful exploitation. The quality of the beam delivered to the sample is limited by the optics' imperfections and misalignment. Though the optics are accurately evaluated in metrology labs equipped with visible-light-based measuring instruments, such ex-situ characterizations do not allow perfect predictions of their beamline performance, since the mechanical and thermal strains imposed by beamline operation cannot be perfectly modelled. In-situ at-wavelength characterization is the natural way to overcome this limitation [1]. In-situ wavefront sensing performed at the optics' operating wavelength (“at-wavelength” metrology) can be used not only to optimize the performance of X-ray optics, but also to correct and minimize the collective distortions of upstream beamline optics (e.g., monochromator, windows, etc.). This issue has become even more critical with the increasing use of active optics on the beamlines on one hand, and with the desire to achieve diffraction-limited and coherence-preserved beams [2] on the other.

NIST high throughput variable kinetic energy hard X-ray photoelectron spectroscopy facility

We present an overview of the National Institute of Standards and Technology beamline X24A at the National Synchrotron Light Source at Brookhaven National Lab and recent work performed at the facility. The beamline is equipped for HAXPES measurements, with an energy range from 2.1 to 6keV with Si(111) crystals. Recent measurements performed at the beamline include non-destructive depth dependent variable kinetic energy measurements of dielectric and semiconductor films and interfaces for microelectronics applications, band alignment at buried interfaces, and the electronic structure of bulk-like materials. The design and operation of the current beamline will be discussed, as well as the future NIST beamline at NSLS II.

Human factors design for the BMIT biomedical beamlines

Operation of a biomedical beamline poses a unique set of operational and instrumentation challenges for a synchrotron facility. From proper handling and care of live animals and animal tissues, to a user community drawn primarily from the medical and veterinary realms, the work of a biomedical beamline is unique when compared to other beamlines. At the Biomedical Imaging and Therapy (BMIT) beamlines at Canadian Light Source (CLS), operation of the beamlines is geared towards our user community of medical personnel, in addition to basic science researchers. Human factors considerations have been incorporated wherever possible on BMIT, including in the design of software and hardware, as well as ease-of-use features of beamline control stations and experiment hutches. Feedback from users continues to drive usability improvements to beamline operations.

Data Management System at the Photon Factory Macromolecular Crystallography Beamline

Macromolecular crystallography is a very powerful tool to investigate three-dimensional structures of macromolecules at the atomic level, and is widely spread among structural biology researchers. Due to recent upgrades of the macromolecular crystallography beamlines at the Photon Factory, beamline throughput has improved, allowing more experiments to be conducted during a user's beam time. Although the number of beamlines has increased, so has the number of beam time applications. Consequently, both the experimental data from users' experiments and data derived from beamline operations have dramatically increased, causing difficulties in organizing these diverse and large amounts of data for the beamline operation staff and users. To overcome this problem, we have developed a data management system by introducing commercial middleware, which consists of a controller, database, and web servers. We have prepared several database projects using this system. Each project is dedicated to a certain aspect such as experimental results, beam time applications, beam time schedule, or beamline operation reports. Then we designed a scheme to link all the database projects.

Study of time and pressure dependent phenomena at the hard x-ray beamline BL9 of DELTA

The beamline BL9 of DELTA (Dortmund ELecTron Accelerator) is a multi-purpose beamline operating in an energy range between 4 and 27 keV. A short overview of the beamline and the experimental endstation is given. Exemplarily three typical applications, namely x-ray diffraction from interfaces, small angle x-ray scattering under high hydrostatic pressure and fast x-ray reflectivity measurements, are discussed in some detail in order to demonstrate the capabilities of the beamline.