Characterization of Diamond and Silicon Carbide Detectors With Fission Fragments
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-09-20 |
| Journal | Frontiers in Physics |
| Authors | M.-L. Gallin-Martel, Yeul Hong Kim, L. Abbassi, A. BĂšs, C. Boiano |
| Institutions | CEA Cadarache, Centre National de la Recherche Scientifique |
| Citations | 5 |
| Analysis | Full AI Review Included |
Characterization of Diamond and Silicon Carbide Detectors With Fission Fragments
Section titled âCharacterization of Diamond and Silicon Carbide Detectors With Fission FragmentsâExecutive Summary
Section titled âExecutive SummaryâThis study characterized wide-gap semiconductor detectors (Diamond and SiC) using mass- and energy-separated Fission Fragments (FF) at the ILL LOHENGRIN spectrometer, aiming for innovative instrumentation in high-flux nuclear physics experiments (like FIPPS).
- Timing Performance: A 500-”m thick single crystal CVD (sCVD) diamond achieved an excellent timing resolution of 10.2 ps RMS for 90 MeV FF (A=98), representing the best value reported for diamond FF detection.
- Energy Resolution (sCVD): The thin sCVD diamond (50 ”m) demonstrated superior energy resolution for FF (A=98) at 90 MeV, achieving 1.4% RMS, compared to 1.6% RMS for the 500-”m thick sCVD detector.
- Energy Resolution (SiC): The 400-”m SiC detector showed a resolution of 3.4% RMS for the same FF, approximately twice as large as the sCVD results.
- Pulse Height Defect (PHD): Significant PHD was observed in sCVD diamond detectors, resulting in an approximate 50% loss of the initial generated charge carriers for FF, weakly dependent on the applied electric field (up to 4 V/”m).
- Polycrystalline CVD (pCVD): pCVD detectors exhibited poor spectroscopic performance due to high inhomogeneity and defects (grain boundaries) but still maintained excellent timing resolution (23.8 ps RMS).
- Application Viability: sCVD diamond detectors are confirmed as the optimal choice for fast, radiation-hard FF detection, suitable for integration into complex in-beam spectroscopy setups like FIPPS.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Best Timing Resolution (sCVD A) | 10.2 ± 0.2 | ps RMS | FF (A=98, 90 MeV) |
| Energy Resolution (sCVD B) | 1.4 | % RMS | FF (A=98, 90 MeV, 50 ”m thick) |
| Energy Resolution (sCVD A) | 1.6 | % RMS | FF (A=98, 90 MeV, 517 ”m thick) |
| Energy Resolution (SiC) | 3.4 | % RMS | FF (A=98, 90 MeV, 400 ”m thick) |
| Pulse Height Defect (PHD) | ~50 | % | Loss of generated charge carriers for FF in sCVD diamond |
| Diamond Band Gap | 5.45 | eV | Intrinsic property |
| Diamond Eeh (Pair Energy) | 13.6 | eV | Energy required to produce an electron-hole pair |
| Diamond Electron Mobility | 1,714 | cm2 V-1 s-1 | Intrinsic property |
| Diamond Hole Mobility | 2,064 | cm2 V-1 s-1 | Intrinsic property |
| Diamond Displacement Energy | 43 | eV | High radiation hardness threshold |
| SiC Displacement Energy | 25 | eV | Comparison value (Silicon) |
| sCVD A Bias Voltage (FF) | -450 | V | Corresponds to 0.9 V/”m electric field |
| sCVD B Bias Voltage (FF) | -200 | V | Corresponds to 4 V/”m electric field |
| SiC Bias Voltage (FF) | -100 | V | Operating voltage |
| SiC N- Layer Thickness | 20 | ”m | Doping concentration ~2 x 1014 cm-3 |
| SiC Substrate Thickness | 350 | ”m | N+ SiC substrate |
| FF Kinetic Energy Range Tested | 35 to 110 | MeV | LOHENGRIN selection |
| Target Neutron Flux (ILL) | ~5 x 1014 | n/s/cm2 | Operating environment |
Key Methodologies
Section titled âKey MethodologiesâThe detector characterization utilized the LOHENGRIN mass spectrometer at the ILL, which provides mass (A/Q) and energy (E/Q) separated heavy ions.
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Detector Preparation:
- Tested detectors included two sCVD, three pCVD, one Diamond-On-Iridium (DOI), and one 4H-SiC p+n diode.
- Diamond detectors were housed in a âsandwichâ configuration with aluminum metallization (50 nm or 100 nm thick) for signal readout from both sides (0° and 180°).
- Bias cycling (e.g., +450 V for 3 min, then -450 V for 1 min ramped) was used to minimize polarization effects, especially in pCVD and DOI samples.
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Pre-Characterization (Laboratory):
- Leakage current vs. bias voltage was measured to infer contact quality.
- Charge Collection Efficiency (CCE) was mapped using a 241Am alpha source (5.5 MeV).
- Spatial homogeneity was assessed using focused particle beams:
- X-ray Beam Induced Current (XBIC, 8.5 keV X-rays) at ESRF (focused to ~1 ”m).
- Electron Beam Induced Current (eBIC, 30 keV electrons) at Institut NĂ©el (weakly penetrating, simulating FF stopping depth).
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Spectroscopic Measurement (Energy Resolution & PHD):
- Detectors were exposed to mass-separated FF (A=98, 84, 144, 131) and light ions (4.75 MeV alpha, 2.7 MeV tritons).
- Readout utilized a dedicated low-noise, fast-response charge sensitive preamplifier (INFN-Milano) with 0.5 ”s Gaussian shaping time.
- PHD was quantified by comparing the linear calibration obtained from alpha/triton measurements (negligible PHD) against the measured FF signal amplitude.
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Timing Measurement (Temporal Resolution):
- Readout used a low-noise broadband RF amplifier (CIVIDEC C2, 2 GHz, 40 dB).
- Waveforms were recorded using a high-speed digital sampling system (Wavecatcher, 3.2 GS/s).
- Timing resolution was determined offline using a numerical Constant Fraction Discrimination (CFD) algorithm applied to the time difference between signals extracted from the two sides (0° and 180°) of a single detector.
Commercial Applications
Section titled âCommercial ApplicationsâThe demonstrated performance characteristics (extreme speed, high radiation hardness, and good energy resolution) make these detectors highly valuable for applications in high-energy physics and nuclear safety.
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Nuclear Physics Instrumentation:
- Fission Product Prompt gamma-ray Spectrometer (FIPPS) at ILL, used for in-beam FF detection and tagging in high-flux thermal neutron environments.
- Recoil separators and mass spectrometers requiring fast timing for Time-of-Flight (TOF) measurements (E-v method).
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Radiation Detection and Monitoring:
- High-rate heavy-ion detection systems where charge recombination (PHD) must be managed or minimized.
- Radiation-hard monitoring systems in high-flux reactors or particle accelerators, leveraging diamondâs high displacement energy (43 eV).
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Homeland Security and Safety:
- Neutron detection systems (using 10B conversion layers, as tested in SiC) requiring stability under prolonged irradiation.
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Advanced Semiconductor Technology:
- Development of high-performance, wide-bandgap solid-state ionization chambers for extreme environments.
View Original Abstract
Experimental fission studies for reaction physics or nuclear spectroscopy can profit from fast, efficient, and radiation-resistant fission fragment (FF) detectors. When such experiments are performed in-beam in intense thermal neutron beams, additional constraints arise in terms of target-detector interface, beam-induced background, etc. Therefore, wide gap semi-conductor detectors were tested with the aim of developing innovative instrumentation for such applications. The detector characterization was performed with mass- and energy-separated fission fragment beams at the ILL (Institut Laue Langevin) LOHENGRIN spectrometer. Two single crystal diamonds, three polycrystalline and one diamond-on-iridium as well as a silicon carbide detector were characterized as solid state ionization chamber for FF detection. Timing measurements were performed with a 500-”m thick single crystal diamond detector read out by a broadband amplifier. A timing resolution of âŒ10.2 ps RMS was obtained for FF with mass A = 98 at 90 MeV kinetic energy. Using a spectroscopic preamplifier developed at INFN-Milano, the energy resolution measured for the same FF was found to be slightly better for a âŒ50-”m thin single crystal diamond detector (âŒ1.4% RMS) than for the 500-”m thick one (âŒ1.6% RMS), while a value of 3.4% RMS was obtained with the 400-”m silicon carbide detector. The Pulse Height Defect (PHD), which is significant in silicon detectors, was also investigated with the two single crystal diamond detectors. The comparison with results from α and triton measurements enabled us to conclude that PHD leads to âŒ50% loss of the initial generated charge carriers for FF. In view of these results, a possible detector configuration and integration for in-beam experiments has been discussed.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2017 - EXILL-a High-Efficiency, High-Resolution Setup for Îł-spectroscopy at an Intense Cold Neutron Beam Facility [Crossref]
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