An X-ray beam profile monitoring system at a beamline front-end combining a single-crystal diamond film and energy discrimination using droplet analysis
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-04-20 |
| Journal | Journal of Synchrotron Radiation |
| Authors | Togo Kudo, Mutsumi Sano, Takahiro Matsumoto, Toshiro Itoga, Shunji Goto |
| Institutions | Japan Synchrotron Radiation Research Institute, SPring-8 |
| Citations | 5 |
| Analysis | Full AI Review Included |
6CCVD Technical Documentation: Single-Crystal Diamond for High-Stability X-ray Beam Monitoring
Section titled â6CCVD Technical Documentation: Single-Crystal Diamond for High-Stability X-ray Beam MonitoringâThis document analyzes the requirements and findings of the research paper âAn X-ray beam profile monitoring system at a beamline front-end combining a single-crystal diamond film and energy discrimination using droplet analysisâ (Kudo et al., 2022). It highlights 6CCVDâs capabilities in supplying the necessary Single-Crystal Diamond (SCD) materials and customization services required for replicating and advancing this critical synchrotron diagnostic technology.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrated a high-precision X-ray beam profile monitoring system essential for Diffraction-Limited Storage Rings (DLSRs) requiring strict light source stability (10 nrad level).
- Material Superiority: Single-Crystal CVD Diamond (SCD) was proven superior to Polycrystalline Diamond (PCD) by eliminating diffraction bright spots caused by crystal grains, resulting in significantly improved image quality.
- Core Application: Monitoring pink-beam X-rays exiting a beamline front-end, crucial for small angular stabilizations of the light source.
- Methodology: X-rays scattered from a thin SCD film (70 ”m) were converted into a cross-sectional image using pinhole optics and digitized by a direct detection 2D CMOS sensor (SOPHIAS-L).
- Energy Resolution: Photon energy discrimination was achieved using âdroplet analysis,â successfully visualizing the spatial distribution of fundamental (12.4 keV) and harmonic radiation components.
- Key Achievement: Accurate beam centroid detection was demonstrated by discriminating the fundamental radiation in the 14 keV to 16 keV range, sharpening the beam profile compared to integrated images.
- Future Improvement: The system requires a detector with higher energy resolution, faster frame rate, and shorter exposure time to operate efficiently at full ring current (100 mA) without an attenuation disk.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental setup and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material Used | Single-Crystal CVD | N/A | Chosen to eliminate diffraction spots |
| Diamond Thickness | 70 | ”m | High X-ray transparency |
| Diamond Dimensions | 15 x 10 | mm | Rectangular film size |
| Polished Surface Roughness (Ra) | < 5 | nm | Required for low scattering noise |
| Crystal Orientation | 3° off-(100) | ° | Tilted surface to minimize diffraction |
| Fundamental Photon Energy | 12.4 | keV | Corresponds to ID gap of 17.26 mm |
| Transmittance at 12.4 keV | 97 | % | Through the 70 ”m SCD film |
| Detector Pixel Size | 30 | ”m | SOPHIAS-L CMOS sensor |
| Detector Frame Rate | 30 | frames s-1 | Used for data acquisition |
| Optimized Energy Range for Centroid | 14 to 16 | keV | Range used for fundamental radiation discrimination |
| Target Light Source Stability | 10 | nrad | Required for DLSR operation |
Key Methodologies
Section titled âKey MethodologiesâThe X-ray beam profile monitoring system relies on precise material selection and controlled experimental parameters:
- Light Source & Beam Conditioning: The experiment utilized the SPring-8 BL05XU in-vacuum undulator. Measurements were conducted at 10 mA beam current (1/10 normal operation) with the fundamental energy set to 12.4 keV. The Front-End (FE) slit aperture was enlarged to 3.6 mm (H) x 2.8 mm (V) to observe the wide spatial distribution.
- Diamond Placement: A 70 ”m thick SCD film (15 mm x 10 mm, 3° off-(100)) was placed 35.5 m from the source point in a high-vacuum chamber (10-6 Pa). The film acts as a scattering screen.
- Imaging System: Forward-scattered X-rays were transmitted through a 250 ”m Beryllium window and imaged using a 10 ”m diameter, 500 ”m thick Tungsten pinhole.
- Single-Photon Condition: A rotating Tungsten attenuation disk (chopper, 30 Hz) was used to reduce the exposure time to 0.7 ms per shot, ensuring the one-photon condition necessary for accurate energy discrimination.
- Detection: A direct-detection 2D CMOS sensor (SOPHIAS-L) with 30 ”m pixels was operated at 30 frames s-1.
- Energy Discrimination (Droplet Analysis): A computer algorithm was applied offline to 10,000 images. This method uses two thresholds (TH1 = 80 ADU, TH2 = 40 ADU) to recover the charge amount shared across adjacent pixels (due to the detectorâs Point Spread Function, PSF), thereby measuring the energy of each photon and enabling energy-resolved imaging.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-quality SCD materials and custom engineering required to replicate and advance this X-ray beam monitoring technology for DLSRs and XFELs.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the successful elimination of diffraction spots and achieve high X-ray transparency, Optical Grade Single Crystal Diamond (SCD) is the required material.
- SCD Wafers: 6CCVD provides high-purity SCD grown via MPCVD, ensuring the low defect density and superior crystalline quality necessary for minimal Bragg diffraction contamination.
- Thickness Control: We offer precise thickness control from 0.1 ”m up to 500 ”m. The 70 ”m film used in this study is a standard offering, and we can provide thinner films for even higher X-ray transmittance or thicker substrates (up to 10 mm) for high heat load applications.
- Boron-Doped Diamond (BDD): For future iterations requiring integrated electrical contacts or sensing layers, 6CCVD offers Boron-Doped Diamond (BDD) films, which can be patterned and metalized for direct charge collection or photoconductive applications.
Customization Potential
Section titled âCustomization PotentialâThe research utilized specific dimensions and surface finishes that align perfectly with 6CCVDâs core customization capabilities:
| Research Requirement | 6CCVD Capability | Value Proposition |
|---|---|---|
| Custom Dimensions (15 mm x 10 mm) | Plates/Wafers up to 125 mm | We provide precision laser cutting to match exact required geometries, including the 15 mm x 10 mm rectangle, ensuring perfect fit into custom vacuum chambers. |
| High Surface Finish (Ra < 5 nm) | Polishing to Ra < 1 nm (SCD) | Our state-of-the-art polishing exceeds the paperâs requirement, minimizing surface scattering and improving the signal-to-noise ratio for pinhole imaging. |
| Crystal Orientation (3° off-(100)) | Custom Off-Cut Angles | We can supply SCD substrates with specific off-cut angles and orientations (e.g., 3° tilt) to optimize scattering conditions and mitigate specific diffraction effects (Laue case). |
| Future Integration (Contacts/Alignment) | In-House Metalization | We offer internal deposition of Au, Pt, Pd, Ti, W, and Cu for creating robust electrical contacts or precise alignment marks directly on the diamond surface, supporting advanced detector designs. |
Engineering Support
Section titled âEngineering SupportâThe success of this X-ray beam monitoring system relies heavily on selecting the optimal diamond properties (thickness, orientation, and surface finish) relative to the X-ray energy and heat load.
6CCVDâs in-house PhD team specializes in material selection and optimization for high-performance Synchrotron and XFEL Diagnostics projects. We provide consultation on:
- Optimizing SCD thickness for specific fundamental energies (e.g., 12.4 keV) to balance scattering signal strength and transmission.
- Designing SCD components for high heat load environments (e.g., 100 mA operation) where thermal management is critical.
- Integrating BDD or metalized SCD layers for advanced, real-time beam position monitoring systems.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
This work has successfully demonstrated a system for monitoring pink-beam X-rays exiting from a beamline front-end, which has a specific spatial distribution based on each energy component. In this study, the X-rays scattered from a single-crystal chemical-vapor-deposited diamond film were converted into a cross-sectional image using pinhole optics, followed by digitization with a direct detection complementary metal-oxide-semiconductor 2D detector. By using single crystals instead of poly-crystals, good quality images were obtained with no diffraction bright spots. As a result of applying photon energy discrimination using the droplet analysis to the image information, the spatial distribution of each energy component of the undulator radiation was successfully visualized. The result was found to be in good agreement with the theoretically calculated result obtained using the synchrotron radiation calculation code SPECTRA . The new synchrotron radiation beam monitor proposed in this paper can serve as a powerful beam diagnostic tool for diffraction-limited rings that require strict light source stability.