Method for visualizing detailed profiles of synchrotron X-ray beams using diamond-thin films and silicon drift detectors
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-04-22 |
| Journal | Journal of Synchrotron Radiation |
| Authors | Togo Kudo, Shinji Suzuki, Mutsumi Sano, Toshiro Itoga, Hiroyasu Masunaga |
| Institutions | Japan Synchrotron Radiation Research Institute |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study presents a novel, semi-nondestructive methodology for visualizing detailed, energy-resolved profiles of synchrotron X-ray beams, specifically addressing contamination issues inherent in conventional monitoring techniques.
- Core Value Proposition: The method accurately determines the true undulator beam center by eliminating contamination from nearby bending magnet (BM) radiation, a significant challenge in high-brightness synchrotron facilities.
- Contamination Suppression: Utilizing the high energy resolution of the Silicon Drift Detector (SDD), photon flux from BM radiation near the beam center was suppressed by approximately four orders of magnitude.
- High Resolution Imaging: The system achieved an energy resolution of 140 eV (FWHM) and a spatial resolution limit of 50 ”m, enabling detailed visualization of undulator harmonics (up to the third order).
- Dual Measurement Modes: Two methods were developed: an SDD scanning mode for high-spatial resolution imaging (1.5 mm aperture) and a Front-End Slit (FES) scanning mode for wide-field visualization (5 mm x 5 mm area).
- Key Components: The technique relies on a robust, thin single-crystal diamond film (70 ”m) acting as a scatterer, coupled with a pinhole camera arrangement and a high-performance SDD.
- Application: The measurements are immediately applicable for achieving the initial alignment of beamlines in advanced synchrotron facilities, such as Diffraction-Limited Storage Rings (DLSRs).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Detector Type | Silicon Drift Detector (SDD) | N/A | Techno AP XSDD50-01 |
| SDD Energy Resolution (ÎE) | 140 | eV (FWHM) | Used for energy-resolved imaging |
| Diamond Film Thickness | 70 | ”m | Single crystal scatterer |
| Diamond Film Location | 35.407 | m | Downstream from light source |
| Undulator Gap (SDD Scan) | 26 | mm | First harmonic peak at 17.3 keV |
| Undulator Gap (FES Scan) | 14.8 | mm | First harmonic peak at 10 keV |
| FES Aperture (High-Res Scan) | 1.5 x 1.5 | mm2 | Used during SDD scanning |
| FES Aperture (Wide-Field Scan) | 0.4 x 0.4 | mm2 | Used during FES scanning |
| Spatial Resolution Limit | 50 | ”m | Established by Pinhole 1 diameter |
| Pinhole 1 Material/Thickness | W / 500 | ”m | Diameter 50 ”m |
| Pinhole 2 Material/Thickness | W/Mo / 350 | ”m | Diameter 200 ”m (used with SDD) |
| BM Contamination Suppression | ~4 | Orders of magnitude | Near the undulator beam center |
| Storage Ring Current | 100 | mA | Standard operating condition |
| SDD Scan Integration Time | 5 | s/point | Total measurement time: 4 h |
| FES Scan Integration Time | 1 | s/point | Total measurement time: 6 h |
Key Methodologies
Section titled âKey MethodologiesâThe visualization of the synchrotron beam profile was achieved using two distinct scanning methods, both relying on a thin diamond scatterer and an energy-resolved SDD.
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High-Spatial Resolution Measurement (SDD Scan):
- Aperture: Front-End Slit (FES) aperture was fixed at 1.5 mm x 1.5 mm.
- Scattering/Imaging: The pink X-ray beam scattered off the 70 ”m single-crystal diamond film. Scattered X-rays passed through Pinhole 1 (50 ”m diameter) and were imaged onto the SDD via Pinhole 2 (200 ”m diameter), achieving a 3.3x magnification.
- Scanning Procedure: The SDD and Pinhole 2 assembly were scanned in two dimensions (X and Z) using a pulse motor, with 200 ”m increments (matching the size of Pinhole 2).
- Data Output: 2000 spectra were acquired over 4 hours, compiled into 2D maps showing energy-resolved intensity (10 bins, 67 eV resolution). This method established the spatial resolution limit of 50 ”m.
-
Wide-Field Measurement (FES Scan):
- Aperture: The FES aperture was reduced to 0.4 mm x 0.4 mm to improve spatial resolution during the scan.
- Scanning Procedure: The FES itself was scanned in 2D across a 5 mm horizontal and vertical range, with a pitch of 0.1 mm.
- Detector Configuration: The SDD and Pinhole 1 (50 ”m) remained fixed, capturing the scattered radiation as the FES moved.
- Data Output: 2500 spectra were acquired over 6 hours, compiled into 2D maps showing energy-resolved intensity (10 bins, 80 eV resolution) across a broad 5 mm x 5 mm field of view. This method successfully visualized the full beam profile after the pre-slit.
Commercial Applications
Section titled âCommercial ApplicationsâThis technology, centered on high-resolution, energy-resolved X-ray beam monitoring using diamond films and SDDs, has direct relevance across several high-tech sectors:
- Advanced Synchrotron Facilities: Essential for the commissioning and operation of fourth-generation Diffraction-Limited Storage Rings (DLSRs) where beam stability and precise center determination are paramount.
- X-ray Beam Position Monitoring (XBPM): Provides a highly accurate, energy-filtered reference standard for calibrating and validating conventional XBPM systems, especially where high-order harmonics or complex beam structures are present.
- High-Heat Load Optics: The use of thin single-crystal diamond films demonstrates their viability as robust, low-Z, semi-nondestructive scatterers capable of withstanding the intense heat load of undulator radiation.
- Energy-Dispersive X-ray Imaging: The methodology validates the use of high-resolution SDDs (or future multi-element SDDs) for fast, energy-resolved imaging in applications such as X-ray fluorescence (XRF) microscopy and spectroscopy.
- Accelerator Feedback Systems: While currently limited by measurement time (hours), the concept provides the foundation for developing faster, energy-resolved 2D detectors (e.g., multi-element SDDs) that could eventually be integrated into high-speed feedback loops for light source stabilization.
View Original Abstract
Contamination from nearby bending magnet radiation hinders precise and accurate determination of the true beam center of undulator radiation. To solve this problem, a semi-nondestructive method was developed to visualize the detailed profile of a synchrotron radiation beam by using a thin diamond film as a scatterer. As the beam passed through the diamond film, scattered X-rays were imaged using a pinhole camera and measured with a two-dimensional silicon drift detector (SDD) scan. With this configuration, the beam center was accurately determined by visualizing the radiation pattern distribution for each energy level of a pink X-ray beam within an aperture size of 1.5 mm Ă 1.5 mm, shaped by a front-end slit (FES) positioned upstream of the monochromator. Additionally, by scanning the FES in two dimensions with a reduced aperture of 0.4 mm Ă 0.4 mm, energy-resolved images were successfully obtained using the SDD at a fixed position. These images revealed the profile of undulator radiation over a broad area (with an aperture extending up to 4 mm) in a pre-slit positioned upstream of the FES, demonstrating good alignment with SPECTRA calculations. This method effectively eliminates contamination from nearby bending magnet radiation, a significant issue in previous approaches, enabling a direct and highly accurate determination of the true beam center.