Production and characterization of large-size diamond detectors for particle tracking and medical applications
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-01-09 |
| Journal | Proceedings of The European Physical Society Conference on High Energy Physics â PoS(EPS-HEP2017) |
| Authors | J. Collot, A. BĂšs, G. Bosson, S. Curtoni, D. Dauvergne |
| Institutions | Centre National de la Recherche Scientifique, Université de Lyon |
| Analysis | Full AI Review Included |
6CCVD Technical Documentation: High-Performance CVD Diamond Detectors for Hadrontherapy and High-Energy Physics
Section titled â6CCVD Technical Documentation: High-Performance CVD Diamond Detectors for Hadrontherapy and High-Energy PhysicsâExecutive Summary
Section titled âExecutive SummaryâThis research validates MPCVD diamondâs suitability as an ultra-fast, large-area sensor for high-rate particle tracking and medical applications, specifically addressing the requirements for online hadrontherapy monitoring.
- Core Application: Validation of synthetic CVD diamond (sCVD, pCVD, and Heteroepitaxial DOI) as beam tagging hodoscopes for real-time dose control in carbon ion/proton hadrontherapy.
- Ultra-Fast Performance: Achieved time resolutions between 20 ps and 90 ps (rms), satisfying the requirements for Time-of-Flight (TOF) measurements crucial for background reduction.
- High Rate Capability: Demonstrated operational viability at count rates greater than 100 MHz, essential for monitoring high-intensity clinical beams.
- Material Scalability: Successfully characterized large-size detectors (up to 2x2 cm2), confirming that polycrystalline CVD (pCVD) is a viable, scalable material option for high-area coverage.
- Processing Validation: Uniform disk-shaped Aluminum (Al) metalization (50 nm thickness) was achieved using plasma-assisted sputtering, demonstrating reproducible electrode manufacturing.
- High Energy Resolution: Measured energy resolutions ranging from 7% to 10% (rms), confirming the ability to unambiguously identify single high-energy carbon ions (95 MeV/u).
- Radiation Hardness: Results reinforce the conclusion that CVD diamondâs intrinsic propertiesâhigh resistivity, large bandgap, and fast carrier mobilityâmake it an ideal radiation-hard sensor.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Count Rate | > 100 | MHz | Required for position and timing measurement. |
| Time Resolution (Best) | 20 | ps (rms) | Achieved using small sCVD/DOI pairing. |
| Time Resolution (Large Area) | 90 | ps (rms) | Measured using 2x2 cm2 pCVD samples. |
| Energy Resolution (Carbon Ion) | 7 | % (rms) | Measured on 300 ”m pCVD with 95 MeV/u 12C beam. |
| Energy Resolution (X-Ray) | 9 | % (rms) | Measured on 300 ”m pCVD with 8.5 keV photons. |
| Detector Thickness Range | 300 - 518 | ”m | Tested dimensions across sCVD, pCVD, and DOI samples. |
| Metalization Thickness | 50 | nm | Deposited Aluminum (Al) layer thickness. |
| Largest Area Tested | 2x2 | cm2 | Polycrystalline CVD (pCVD) detector area. |
| Alpha Particle Mean Free Path | ~12 | ”m | Significantly smaller than detector thickness. |
| Charge Carrier Mobility | High | N/A | Contributes to signal response of âfew tens of picoseconds.â |
Key Methodologies
Section titled âKey MethodologiesâThe large-size diamond sensors were manufactured and characterized using advanced plasma deposition, specialized metalization, and high-energy beam facilities.
- Material Growth: Diamonds were synthesized using Microwave Plasma Enhanced Chemical Vapor Deposition (MPCVD).
- Single Crystal (sCVD) grown homo-epitaxially on HPHT seeds (limited to < 1 cm2).
- Polycrystalline (pCVD) grown on diamond nanocrystal seeds (scalable to several cm2).
- Diamond-on-Iridium (DOI) hetero-epitaxial growth for enhanced area scalability (> 1 cm2).
- Detector Metalization: Disk-shaped metal contacts were applied using the Distributed MicroWave Plasma (DMW) technology developed by LPSC.
- Surface Preparation: Initial reactive plasma cleaning step.
- Deposition: Plasma-assisted sputtering to deposit 50 nm of Aluminum (Al) on both sides.
- Signal Readout Chain: Devices were mounted on 50 Ω impedance holders using SMA connectors.
- Preamplifiers: Tested with CIVIDEC C2 low-noise broadband RF amplifier and DBA III Diamond Broadband Amplifier.
- Data Acquisition: Waveform readout utilized a 500 MHz, 3.2 GS/s digital sampling âWavecatcherâ system, supplemented by a 2 GHz, 20 GS/s analog bandwidth DSO for 2D response mapping (XBIC).
- Characterization Sources:
- Alpha and Beta Sources: Used radioactive sources (e.g., 233U, 90Sr) to measure Charge Collection Distance (CCD) and signal response based on bias polarity.
- X-Ray Beam: Focused 8.5 keV photon micro-beam (ESRF ID21) used for X Beam Induced Current (XBIC) surface mapping and energy resolution.
- Ion Beam: 95 MeV/u 12C carbon ion beam (GANIL) used to evaluate single ion detection characteristics and energy resolution.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the specialized MPCVD materials and custom processing required to replicate or advance this research into commercial systems for hadrontherapy monitoring and high-energy physics. We specialize in producing detectors that offer superior uniformity and scalability compared to the samples characterized.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve optimal performance and scalability for fast timing applications (e.g., CLaRyS collaboration hodoscope), 6CCVD recommends the following specific material grades:
| Material Grade | Target Application | Key 6CCVD Advantage |
|---|---|---|
| Optical Grade SCD | Ultra-Fast Timing Hodoscope (replicating 20 ps results) | Highest crystalline quality (Ra < 1 nm polish), maximizing Charge Collection Distance (CCD) and signal uniformity. SCD wafers up to 500 ”m thick. |
| High-Purity PCD Wafers | Large-Area Beam Tracking Detectors | Scalable dimensions up to 125mm (5 inches), well beyond the 2x2 cm2 tested. Thickness control from 0.1 ”m up to 500 ”m. |
| Boron-Doped Diamond (BDD) | Dosimetry and Reference Electrodes | Available as both films and thick substrates (up to 10 mm) for specialized dosimetry needs, leveraging diamondâs inherent radiation hardness. |
Customization Potential
Section titled âCustomization PotentialâThe research highlights the need for precise dimensional control, large area availability, and specific metal contacts. 6CCVD is uniquely positioned to meet these engineering demands:
- Scalability for Large Systems: We routinely manufacture inch-size PCD wafers (up to 125mm). This capability overcomes the area limitations reported for sCVD (< 1 cm2) and significantly extends the scalability of the pCVD solutions tested (2x2 cm2).
- Precision Thickness Control: The paper tested thicknesses between 300 ”m and 518 ”m. 6CCVD guarantees thickness uniformity within this range and offers substrates up to 10 mm, tailored to specific energy deposition and capacitance requirements.
- Custom Metalization Services: The tested detectors utilized 50 nm Aluminum (Al) contacts. 6CCVD offers in-house deposition of Al, alongside a full suite of materials crucial for bonding and robust contacts (Au, Pt, Pd, Ti, W, Cu). We can deliver finished detectors with custom geometries (e.g., the required disk shape) directly on the diamond surface.
- High-Quality Polishing: For applications requiring precise bonding or minimizing surface leakage, 6CCVD provides industry-leading polishing, achieving surface roughness of Ra < 1 nm for SCD and Ra < 5 nm for large-area PCD.
Engineering Support
Section titled âEngineering SupportâThe successful development of CVD diamond detectors for precision hadrontherapy beam tagging requires advanced material knowledge and detector physics expertise. 6CCVDâs in-house PhD engineering team specializes in connecting material properties (like grain boundary reduction in PCD or doping control in SCD) to target device performance (e.g., minimizing time walk or maximizing Charge Collection Efficiency).
Our team can assist researchers and engineers in selecting the optimal crystal type and processing recipe necessary to maximize count rate capability and achieve the demanding time resolution required for hadrontherapy beam tagging projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Large-size diamond detectors have been produced and tested with the aim of achieving reliable & efficient sensors for particle tracking or medical applications. Poly- and single-crystal CVD diamond samples were submitted to various ionizing particles. Their metallization was performed by using Distributed MicroWave Plasmas, a process developed by LPSC. Their detection performance was investigated using α and ÎČ radioactive sources, 95 MeV/u carbon beams from GANIL (Caen France) and short-bunched 8.5 keV photons from ESRF. This study is part of the ANR project MONODIAM-HE and of the CLaRyS collaboration for the on-line dose monitoring of hadrontherapy. The goal here is to provide large-area detectors with a high detection efficiency for carbon or proton beams, yielding time and position measurement at count rates greater than 100 MHz. A time resolution ranging from 20 ps up to 40 ps and an energy resolution varying from 7 % up to 10% were measured. It allowed us to conclude that poly-crystal CVD diamond detectors are good candidates for this application.