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202 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
Optics	Development of laterally graded X-ray multilayer optics Arindam Majhi , Wadwan Singhapong , Wai Jue Tan , Andrey Sokolov , Stefano Agrestini , Mirian Garcia-Fernandez , Ke-Jin Zhou , Andrew C. Walters , Chris Bowen , Alexander J. G. Lunt , Hongchang Wang , Kawal J. Sawhney Advanced Materials Technologies 58 DOI: 10.1002/admt.202501364 Open Access Show Abstract ▼ Abstract: Laterally graded multilayer optics play an important role in advanced X-ray applications, enabling precise control of beam properties for spectroscopic and focusing techniques. The Multilayer Deposition System (MDS) at Diamond Light Source (DLS) has demonstrated its ability to fabricate highly precise laterally graded X-ray optics. Developing such optics is challenging due to stringent requirements for precise lateral thickness variations and sagittal uniformity, achieved through optimized substrate speed profiles and advanced mask design. This study presents a comprehensive investigation into the design, fabrication, and characterization of laterally graded multilayers. An adjustable mask design improves sagittal uniformity and reduces optimization times. The structural and optical performance of the multilayers is evaluated, confirming their suitability for synchrotron applications. Two types of laterally graded multilayers were developed: one with a constant lateral gradient (0.005 nm/mm) for O-K edge polarizers, achieving sagittal thickness variations of approximately 0.3–0.4% across an 80 mm substrate, and another featuring a strong variable gradient from 0.037 to 0.112 nm/mm, designed to match the elliptical periodicity profile. The constant gradient multilayer polarizer has been successfully implemented on the state-of-the-art I21 beamline at DLS, highlighting the MDS's role in producing next-generation X-ray optics that meet the stringent demands of synchrotron beamlines.	Jan 2026
Metrology Optics	A new, ultra-stable lab for nano-metrology of x-ray optics at Diamond Light Source S. G. Alcock , I.-T. Nistea , M. Bazan Da Silva , J. Kelly , G. Preece , A. Howell , K. Sawhney Review Of Scientific Instruments 96 The 8th International Workshop on X-Ray Optics and Metrology DOI: 10.1063/5.0287189 Open Access Show Abstract ▼ Abstract: A new Optics Metrology Laboratory for assembling and characterizing beamline x-ray optical systems has been built. This replaces the old laboratory, which was demolished to make space for construction of a new flagship beamline for the forthcoming Diamond-II facility upgrade. The new cleanroom laboratory is located between several beamlines and laboratories, which intermittently generate significantly higher levels of acoustic noise and floor vibrations. A threefold design strategy was employed to create an ultra-stable environment for the sensitive, optical metrology instruments. First, the walls, ceiling and doors of the laboratory were constructed to attenuate acoustic noise. Second, the air handling systems were designed to minimize self-production of noise and vibrations. Finally, engineering solutions were developed to further isolate the metrology instruments from environmental fluctuations. Overall, despite higher levels of external disturbances, this strategy enables nano-metrology to be successfully conducted in the new laboratory. The shielded environment around each instrument achieves noise rating NR30, which is 5–25 dB quieter than the old laboratory. Over 60-h, the temperature inside the Diamond-NOM’s enclosure varied by only 0.004 °C rms, and humidity changed by <1% RH. All optical metrology instruments are now performing better than in the old laboratory: the slope error repeatability of Diamond-NOM is improved from 15 to 9 nrad rms; the GTX micro-interferometer has measured super-polished substrates with micro-roughness <40 pm rms; the new gantry for Speckle Angular Measurement is commissioned; and the HDX Fizeau interferometer has measured mirrors with slope errors <50 nrad.	Oct 2025
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1 B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS Optics	High-efficiency multilayer grating for enhanced tender X-ray photoelectron spectroscopy Wai Jue Tan , Arindam Majhi , Wadwan Singhapong , Andrew C. Walters , Matthijs A. Van Spronsen , Georg Held , Burcu Karagoz , David C. Grinter , Pilar Ferrer , Guru Venkat , Qiushi Huang , Zhe Zhang , Zhanshan Wang , Patrick Yuheng Wang , Andrey Sokolov , Hongchang Wang , Kawal Sawhney Scientific Reports 15 DOI: 10.1038/s41598-025-19440-6 Open Access Show Abstract ▼ Abstract: X-ray Photoelectron Spectroscopy (XPS) is a powerful tool for probing the chemical and electronic states of materials with elemental specificity and surface sensitivity. However, its application in the tender X-ray range (1–5 keV) for synchrotron radiation has remained limited due to the limited choice of optics capable of maintaining high reflectivity and efficiency in this energy window. To address this, multilayer (ML) grating structures have become increasingly popular, offering significantly higher efficiency than SL coatings in the tender X-ray region. This paper presents the development of ML laminar gratings optimised for enhancing efficiency in the tender X-ray range, and capable of retaining performance under intense X-ray exposure in the oxygen partial pressure of 10 mbar. The ML coating quality was verified through X-ray reflectivity (XRR), XPS and near-edge X-ray absorption fine structures (NEXAFS) measurements, while the performance of the grating was validated through beamline flux transmission and XPS measurements. The MLLG demonstrated 22 higher intensity in flux and XPS, significantly improving the signal-to-noise ratio. Most importantly, the MLLGs outperformed traditional designs by offering improved spectral resolution while maintaining measurement capability at varying values without compromising the intensity. Furthermore, we demonstrated that the incorporation of nitrogen during deposition further enhances flux transmission.	Oct 2025
B16-Test Beamline	Characterisation and quantification of the ‘Excess-Leakage-Current’ effect in Redlen HF-CdZnTe at > 106 ph s-1 mm-2 B. Cline , D. Banks , M. Bishop , A. Davis , J. Harris , M. Hart , S. Knowles , T. Nicholls , J. Nobes , S. Pradeep , M. Roberts , M. C. Veale , M. D. Wilson , V. P. Dhamgaye , O. J. L. Fox , K. J. S. Sawhney , S. Scully Journal Of Instrumentation 20 DOI: 10.1088/1748-0221/20/10/P10021 Diamond Proposal Number(s): [36472] Open Access Show Abstract ▼ Abstract: In this paper, results are presented from the characterisation of a 2 mm thick Redlen Technologies high-flux-capable Cadmium Zinc Telluride (HF-CZT) sensor hybridised to the small-pixel, spectroscopic-imaging HEXITEC_MHz ASIC. Dynamic datasets were taken on the B16 Test Beamline at the Diamond Light Source to study a previously-identified 'excess-leakage-current' phenomenon in HF-CZT, where additional leakage current was temporarily generated upon the application of an X-ray flux. A study of the response of the detector as a function of X-ray intensity demonstrated a measurable excess leakage current signal above 105 ph s-1 mm-2. At a 20 keV flux of 7.81 × 106 ph s-1 mm-2, this effect contributed a signal equivalent to 3.79 ± 1.59 nA mm-2in addition to the expected photocurrent. On removal of X-rays at this flux, this excess leakage current took ∼ 10 s to decay below the noise floor of the detector. This long lifetime has implications for detectors required to operate at high frame rates and fluxes. The use of a small-pixel detector also allowed the spatial variation of this effect to be studied. A per-pixel comparison between the magnitude of the excess leakage current and the spectroscopic performance of the pixel showed no correlation. This suggests that the phenomenon is less likely to be a bulk-crystal effect and more likely the result of the properties of the CZT surface or metal/semiconductor interface. An Arrhenius analysis of the temperature-dependence of the dark and excess leakage currents in the detector yielded values of 0.69 ± 0.04 eV and 0.13 ± 0.01 eV respectively. The change in dark current with temperature is consistent with deep levels pinning the Fermi level close to the mid band gap, whilst the activation energy of the excess leakage current suggests shallower defects at the metal-semiconductor interface are responsible.	Oct 2025
B16-Test Beamline Optics	Development of high-performance multilayer monochromators Wadwan Singhapong , Arindam Majhi , Wai Jue Tan , Vishal Dhamgaye , Riley Shurvinton , Paresh Pradhan , Igor Dolbnya , Lucia Alianelli , Chris Bowen , Alexander J. G. Lunt , Hongchang Wang , Kawal Sawhney Advanced Optical Materials 11822 DOI: 10.1002/adom.202501312 Open Access Show Abstract ▼ Abstract: Multilayer monochromators are crucial optical elements for monochromatizing intense X-ray beams in applications demanding high photon flux with moderate energy resolution. Achieving high-performance multilayer monochromators requires optimizing multilayer parameters, using high-quality substrates, and precisely controlling the deposition process to ensure high reflectivity and eliminate stripe artifacts. This paper presents the design and development, and characterization of double multilayer monochromators (DMM). These coatings are deposited using an optimized mask design to ensure <0.3% sagittal thickness uniformity and employing reactive sputtering in nitrogen gas (N2) - to enhance multilayer reflectivity. A high reflectivity of 88.7% at 14.0 keV and 85.6% at 22.4 keV is achieved. Furthermore, stripe-free imaging is achieved in double-reflection geometry via the use of high-quality substrates produced using the in-house ion beam figuring machine. These findings offer valuable insights for developing high-performance DMMs, paving the way for the next generation of synchrotron optics and instruments.	Aug 2025
Metrology Optics	Improving the quality of X-ray mirrors: An inter-lab, optical metrology collaboration to guide deterministic polishing Simon G. Alcock , Ioana-Theodora Nistea , Murilo Bazan Da Silva , Kawal Sawhney , Norman Niewrzella , Holger Lasser , Amparo Vivo , Ray Barrett , Jana Buchheim , Grzegorz Gwalt , Frank Siewert , Sibylle Spielmann , Uwe Flechsig , Silja Schmidtchen , Maurizio Vannoni , Josep Nicolas , Muriel Thomasset , Francois Polack Review Of Scientific Instruments 96 The 8th International Workshop on X-Ray Optics and Metrology DOI: 10.1063/5.0287341 Open Access Show Abstract ▼ Abstract: The surface quality of x-ray mirrors is a major constraint on optical performance at synchrotron light and free electron laser facilities. A limiting factor for creating state-of-the-art optics is the accuracy of metrology data to deterministically guide the polishing tool to correct surface errors. The “MooNpics” (Metrology On One-Nanometer-Precise Optics) collaboration aims to improve optical metrology capabilities at European facilities to enable reproducible measurement of long or curved optics with height errors <1 nm rms and slope errors <100 nrad rms. Three challenging x-ray optics were measured by several labs using a variety of instruments. The mirrors, chosen to challenge and explore different aspects of optical metrology, were as follows: a 1 m-long, ultra-flat (radius of curvature R > 100 km); an ellipse with added parabolic arcs; and a strongly curved sphere (R ∼ 9.3 m) with an added spatially varying chirp. This study highlighted calibration issues with several instruments, which were subsequently corrected. In this paper, we present results about the ellipse mirror. Based on metrology data provided by the collaboration, two cycles of ion beam figuring improved all aspects of the mirror, including correcting the ellipse parameters, reducing high- and mid-frequency spatial polishing errors, and refining the shape of the parabolic arcs. Overall, the slope and height errors were improved by a factor of ∼10. We also show how the round-robin measurement exercise helped refine “best practice” procedures for mounting optics, alignment, and data acquisition and analysis methods. It is hoped that this collaborative project will ignite further improvements in the production quality of x-ray optics to benefit many scientific communities around the world.	Aug 2025
B16-Test Beamline Optics	Development of multilayer monochromators for stripe-free X-ray imaging Riley Shurvinton , Paresh Pradhan , Murilo Bazan Da Silva , Wadwan Singhapong , Wai Jue Tan , Arindam Majhi , Vishal Dhamgaye , Hongchang Wang , Kawal Sawhney Optics Express 33 DOI: 10.1364/OE.562887 Open Access Show Abstract ▼ Abstract: Multilayer (ML) monochromators are essential components in synchrotron radiation facilities, widely used for X-ray imaging and X-ray diffraction, as well as select X-ray spectroscopy techniques. However, ML monochromators introduce stripe artefacts to the reflected beam, which degrade the quality of the X-ray images. These stripe artefacts originate from figure errors on the monochromator’s surface, which are challenging to minimise for most manufacturers. In this study, we demonstrate stripe-free imaging from ultra-high-quality ML monochromators. We employed a state-of-the-art ion beam figuring (IBF) technique to produce multilayer substrates with a cutting-edge slope error of less than 30 nrad root mean squared (rms). These substrates were coated in an advanced multilayer deposition system, enabling the production of uniform multilayer coatings. The performance of the ML monochromators was tested at the B16 test beamline at the diamond light source. Speckle-based metrology was used to verify the theoretical link between wavefront curvature and the appearance of stripe artefacts. We obtained stripe-free X-ray images from the newly fabricated ML monochromators in both single-bounce and double-bounce configurations, with excellent image clarity and flat field uniformity. This represents a breakthrough in the production of ML monochromators.	Aug 2025
Optics	An automated and robust method for modelling X-ray beamlines with plane grating monochromators Patrick Yuheng Wang , Murilo Bazan Da Silva , Georg Held , Hongchang Wang , Kawal Sawhney , Andrew C. Walters Journal Of Synchrotron Radiation 32 DOI: 10.1107/S1600577525003200 Open Access Show Abstract ▼ Abstract: The plane grating monochromator (PGM) is an optical instrument used in the majority of soft X-ray beamlines. Despite its ubiquity, the PGM efficiency can easily be overestimated, because the geometry of many modern PGMs can lead to unexpected blocking of the beam. We have developed a new workflow in Python for simulating PGMs, thus extending the capabilities of SHADOW3, a well established ray tracing software tool. We have used our method to simulate the flux on branch C of the Versatile Soft X-ray (VerSoX) beamline B07 at Diamond Light Source. The simulation results demonstrate qualitative agreement with the experimental measurements, confirming the robustness of the proposed methodology.	Jul 2025
Optics	Characterization of cryo-cooled silicon crystal monochromators via measurement of flux versus power Lucia Alianelli , Hossein Khosroabadi , John Sutter , Andrew C. Walters , Pierpaolo Romano , Kalotina Geraki , Francesco Carla , Jonathan Rawle , Sarah Barnett , Kawal Sawhney Journal Of Synchrotron Radiation 32 DOI: 10.1107/S160057752500342X Open Access Show Abstract ▼ Abstract: A study on the thermal load of cryogenically cooled silicon in synchrotron double-crystal monochromators is presented, based on experimental data from four different beamlines at Diamond Light Source. Different amounts of power are deposited on the first monochromator crystal by varying the storage ring current. The resulting crystal deformation causes a decline in the diffraction efficiency when power and power density are above threshold values. The results are compatible with an analytical model of thermo-mechanical deformation. Acceptable monochromator heat load values are determined with this model, to ensure optimal function of the monochromator. This model, previously tested against finite element analyses, is now validated against measured data and it will be used as a tool for initial analysis of monochromator performance on upgraded photon sources.	Jul 2025
Optics	Optimization of high-performance multilayer monochromator at the Diamond Light Source Wadwan Singhapong , Arindam Majhi , Wai Jue Tan , Lucia Alianelli , Chris Bowen , Alexander J. G. Lunt , Hongchang Wang , Kawal Sawhney 15th International Conference on Synchrotron Radiation Instrumentation (SRI 2024) DOI: 10.1088/1742-6596/3010/1/012048 Open Access Show Abstract ▼ Abstract: Multilayer monochromators offer substantial advantages over traditional crystal-based monochromators. By integrating a multilayer structure, these monochromators can efficiently deliver a high photon flux density and speed up the data acquisition processes, thereby significantly enhancing synchrotron-based experiments. This study focuses on advancing the development of multilayer optics used for the monochromator upgrade of the KMX I24 beamline at the Diamond Light Source. The multilayer monochromator is designed to operate optimally at energies of 12.4 keV and 22.4 keV to maximize the flux. Two multilayer systems including NiV/B4C and Ru/B4C are fabricated using the newly developed Multilayer Deposition System at the Diamond Light Source under the optimized condition. Results indicate that replacing Ni with NiV improves the sputtering stability and interface roughness, while reactive sputtering of Ru/B4C enhances the interface quality of the multilayer. A reflectivity of 92.8% and 89.2% is achieved at 8.048 keV for a 150-bilayer of NiV/B4C and a 70-bilayer of Ru/B4C, respectively.	May 2025

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