Diamond Detector Technology - Status and Perspectives
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-11-09 |
| Journal | Proceedings of The European Physical Society Conference on High Energy Physics â PoS(EPS-HEP2017) |
| Authors | M. Reichmann, Andreas V. Alexopoulos, M. Artuso, F. Bachmair, L. BĂ€ni |
| Institutions | Karlsruhe University of Education, Syracuse University |
| Citations | 1 |
| Analysis | Full AI Review Included |
Diamond Detector Detector Technology for HL-LHC Applications
Section titled âDiamond Detector Detector Technology for HL-LHC ApplicationsâExecutive Summary
Section titled âExecutive SummaryâThis documentation summarizes the technical findings of the RD42 Collaboration regarding the deployment and optimization of Chemical Vapour Deposition (CVD) diamond detectors for extreme radiation environments, specifically the High-Luminosity Large Hadron Collider (HL-LHC).
- Proven Radiation Hardness: CVD diamond (Single Crystal and Polycrystalline) is confirmed as a robust sensor material, demonstrating stable performance following irradiation up to $2.2 \times 10^{16} \text{p/cm}^2$, confirming its role as a key technology for future tracking layers.
- Superior Material Properties: Diamond exhibits inherent advantages over silicon, including a high band gap (5.5 eV), large displacement energy (42 eV/atom), and thermal conductivity that is four times higher than silicon.
- High Rate Stability: Detectors showed stable pulse height signals (variation <5%) when exposed to extremely high particle fluxes up to 20 MHz/cm$^2$, essential for HL-LHC instantaneous luminosity monitoring.
- Successful Deployment: CVD diamond detectors are already established in Beam Condition Monitors (BCMs) across all four major LHC experiments, including the recently recommissioned ATLAS Diamond Beam Monitor (DBM).
- 3D Architecture Breakthrough: The development of 3D pixel detectors in pCVD successfully reduced the charge carrier drift distance below the trap-limited mean free path (<75 ”m post-irradiation), resulting in >80% charge collection efficiency.
- Near-Silicon Efficiency: The latest 3D pixel prototype achieved 98.5% detection efficiency, demonstrating performance comparable to silicon pixel detectors (99.2% relative efficiency).
Technical Specifications
Section titled âTechnical SpecificationsâThe following key parameters and performance metrics were established through the characterization of scCVD and pCVD diamond detectors in high-radiation environments.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| HL-LHC Design Fluence (2028) | $2 \times 10^{16}$ | $\text{n}_{eq}/\text{cm}^2$ | Target dose for innermost tracking layer |
| Maximum Irradiation Dose Tested | $2.2 \times 10^{16}$ | $\text{p/cm}^2$ | Equivalent to ~500 Mrad |
| High Rate Stability Tested (Max Flux) | 20 | MHz/cm$^2$ | Pulse height stable (<5% dependence) |
| Diamond Band Gap | 5.5 | eV | Intrinsic material property |
| Displacement Energy | 42 | eV/atom | Indicates radiation damage threshold |
| Thermal Conductivity Ratio (vs Si) | 4 | Higher | Critical for detector cooling |
| ATLAS DBM Detector Thickness | 500 | ”m | PCD material used in beam monitors |
| Minimum Charge Carrier MFP (Post-Irradiation) | <75 | ”m | Trap limited distance in heavily irradiated material |
| 3D Detector Cell Size (Latest Prototype) | $100 \times 100$ | ”m | Optimized for reduced drift distance |
| 3D Column Production Efficiency | >99 | % | High yield achieved in fabrication |
| 3D Pixel Detector Efficiency (Absolute) | 98.5 | % | Preliminary beam test result |
| 3D Pixel Detector Efficiency (Relative to Si) | 99.2 | % | Relative efficiency comparison |
Key Methodologies
Section titled âKey MethodologiesâThe research leveraged specialized techniques in material growth, processing, and high-energy beam characterization to validate the diamond detector technology.
- CVD Diamond Sourcing: Acquisition of high-quality Single Crystal CVD (scCVD) and Polycrystalline CVD (pCVD) diamond from industrial partners (Element Six and II-VI) to ensure detector grade purity.
- Detector Fabrication: Application of specific recipes for cleaning and metalization (Au, Pt, Ti contacts implied for bonding) to define pad, strip, and pixel electrode geometries on the diamond surface [18].
- 3D Detector Processing: Manufacturing of novel 3D architectures involving precise column drilling (etching) into the diamond sensor, achieving cell sizes down to $100 \text{ ”m} \times 100 \text{ ”m}$ with near-perfect column yield (>99% efficiency).
- Readout Integration: Final 3D pixel sensors were metalized and bump bonded to advanced pixel readout chips (e.g., CMS pixel ROC PSI46digV2.1) to test integrated detector performance.
- Radiation Tolerance Studies: Sensors were exposed to diverse particle fields, including 24 GeV protons, 800 MeV protons, ~1 MeV reactor neutrons, and 200 MeV pions, to determine the damage constant ($\kappa$) using the Mean Free Path (MFP) damage equation.
- High Rate Beam Testing: Use of the $\pi\text{M}1$ beam line at PSI HIPA to provide continuous $\pi^{+}$ beams (260 MeV/c) with tunable fluxes ranging from 1 kHz/cm$^2$ up to 10 MHz/cm$^2$ to verify signal stability under maximum expected HL-LHC flux conditions.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is positioned as an ideal partner to supply the advanced CVD diamond materials required to replicate, test, and further develop the high-performance radiation detectors documented in this research.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the high radiation-tolerance performance and enable complex 3D structures, 6CCVD recommends the following specific materials from our catalog:
| Application Target | 6CCVD Material Recommendation | Required Specification Match |
|---|---|---|
| HL-LHC Tracking Layers | Detector Grade Polycrystalline Diamond (PCD) | Custom wafers up to 125mm diameter for large-area coverage; Thickness control up to 500 ”m (matching DBM). |
| High-Resolution Beam Monitors | High-Purity Single Crystal Diamond (SCD) | Small-area detectors (like the $0.25 \text{ cm}^2$ reference samples); Thickness control from 0.1 ”m up to 500 ”m. |
| Integrated Contacts / Electrodes | Boron-Doped Diamond (BDD) | Material available for high conductivity regions or micro-column structures where doping enhances charge injection/collection efficiency. |
Customization Potential
Section titled âCustomization PotentialâThe success of the RD42 collaboration relies heavily on precision fabrication (pixelization, strip patterns, and 3D drilling). 6CCVD provides the necessary integrated services to meet these advanced demands.
- Large Format Processing: We offer custom PCD plates/wafers up to 125mm diameter, exceeding the size requirements for the reported DBM modules (500 ”m thick).
- Precision Thickness & Dimensions: We routinely provide SCD and PCD substrates with precise thickness control necessary for optimizing Charge Collection Distance (CCD) or reducing material budget, ranging from 0.1 ”m to 500 ”m.
- Advanced Metalization Services: The reported integration requires complex multi-layer contacts for bump bonding. 6CCVD offers in-house deposition and patterning of standard metal stacks, including Ti/Pt/Au, Pt, Pd, W, and Cu, suitable for reliable ASIC interconnection.
- Micro- and Nanoscale Polishing: Achieving high efficiency in 3D structures requires superb surface quality. Our polishing guarantees $\text{Ra} < 1 \text{ nm}$ for SCD and $\text{Ra} < 5 \text{ nm}$ for large-area PCD, ensuring optimal metal adhesion and reduced charge trapping at the surface.
- Custom Geometry Shaping: We utilize advanced laser cutting techniques to provide custom shapes and dimensions required for detectors that must conform tightly to experiment geometry (e.g., mounting symmetrically around the beam pipe).
Engineering Support
Section titled âEngineering Supportâ- Application-Specific Material Selection: 6CCVDâs in-house PhD team can assist engineering groups in material selection and specification development for similar High Energy Physics (HEP), Radiation Monitoring, and Neutron Detection projects.
- Consultation on 3D Processing: We offer support regarding the material requirements for advanced 3D structures, focusing on optimizing the CVD growth recipe to facilitate high-efficiency micro-column processing.
- Global Logistics: We ensure reliable global shipping, managing DDU (Delivered Duty Unpaid) as a default, with DDP (Delivered Duty Paid) options available for streamlined delivery to complex international research sites like CERN or PSI.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The planned upgrade of the LHC to the High-Luminosity-LHC will push the luminosity limits above the original design values. Since the current detectors will not be able to cope with this environment ATLAS and CMS are doing research to find more radiation tolerant technologies for their innermost tracking layers. Chemical Vapour Deposition (CVD) diamond is an excellent candidate for this purpose. Detectors out of this material are already established in the highest irradiation regimes for the beam condition monitors at LHC. The RD42 collaboration is leading an effort to use CVD diamonds also as sensor material for the future tracking detectors. The signal behaviour of highly irradiated diamonds is presented as well as the recent study of the signal dependence on incident particle flux. There is also a recent development towards 3D detectors and especially 3D detectors with a pixel readout based on diamond sensors.