Test of Diamond sCVD Detectors at High Flux of Fast Neutrons

At a Glance

Metadata	Details
Publication Date	2025-08-07
Journal	Particles
Authors	L. Weissman, A. Shor, Sergey Vaintraub
Institutions	Soreq Nuclear Research Center, Israel Atomic Energy Commission
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Flux sCVD Diamond Detectors

Executive Summary

This research validates the exceptional performance of single-crystal Chemical Vapor Deposition (sCVD) diamond detectors for high-rate neutron spectroscopy and timing applications, directly supporting 6CCVD’s core market.

Extreme Flux Validation: SCD detectors maintained good spectroscopic and timing performance at fast neutron flux densities up to 10¹⁰ n/s/cm² (14 MeV neutrons), significantly higher than previously reported tests.
Spectroscopic Excellence: Achieved an energy resolution of 13 keV FWHM for 5.5 MeV alpha particles, comparable to high-quality silicon detectors, demonstrating superior charge collection properties in sCVD.
Timing Capability: Confirmed the potential for sub-nanosecond time resolution, essential for Time-of-Flight (TOF) neutron energy tagging in pulsed accelerator environments like SARAF Phase II.
Active Target Utility: The detector serves a dual role: a high-rate neutron flux monitor and an active target for critical nuclear physics measurements, specifically the ¹²C(n,n’)3α cross-section.
Material Specification: The successful detectors were 140 µm thick sCVD diamond, utilizing a 100 nm Titanium (Ti) electrode, a configuration 6CCVD can replicate and optimize.
Radiation Hardness: The findings reinforce sCVD diamond’s superior radiation hardness (cited up to 10 MGy), making it ideal for fusion reactor diagnostics and intense accelerator facilities.

Technical Specifications

The following hard data points were extracted from the experimental results, demonstrating the high-performance metrics achieved by the sCVD diamond detectors.

Parameter	Value	Unit	Context
Detector Material	Single Crystal CVD (sCVD)	N/A	B3 Grade Diamond
Detector Thickness	140	µm	Active volume used in tests
Detector Area	10	mm²	Detector surface area
Neutron Energy (Tested)	14	MeV	Generated via t(d,n) reaction
Peak Neutron Flux Density (Validated)	10¹⁰	n/s/cm²	Performance validated at 25 cm distance
Maximum Neutron Flux Density (Close)	1.9 x 10¹¹	n/s/cm²	Close geometry (5 cm)
Alpha Energy Resolution (FWHM)	13	keV	Using slow CX-L amplifier (1.2 µs shaping)
Fast Timing Resolution (FWHM)	35	keV	Using fast C6 amplifier (10 ns shaping)
Bias Voltage	+120	V	Operating voltage
Electrode Material	Titanium (Ti)	100 nm	Detector dead layer
Vacuum Pressure	3 x 10^-5	mbar	Test chamber environment

Key Methodologies

The experiment successfully tested sCVD detectors under high-flux conditions using a combination of standard nuclear physics techniques and advanced pulsed neutron generation.

Detector Preparation: Two 140 µm thick, 10 mm² sCVD diamond detectors (B3 grade) were acquired, featuring a 100 nm Titanium electrode.
Source Calibration: Initial tests utilized standard spectroscopic triple alpha sources (²³⁹Pu, ²⁴¹Am, ²⁴⁴Cm) and a ²⁵²Cf fission source for energy calibration and waveform analysis.
Neutron Generation: An ING-031 pulsed neutron generator (t(d,n) reaction) produced 14 MeV neutrons in short bursts.
Pulsed Parameters: Neutron pulses occurred at a frequency of 30 Hz, with a duration of approximately 0.5 µs (above 10% maximum amplitude).
Amplification Strategy: Both slow (CX-L, 1.2 µs shaping time) and fast (C6, 10 ns shaping time) spectroscopic amplifiers were used to optimize for either energy resolution or timing speed.
Geometry Testing: Detectors were placed at 5 cm (high flux, high pileup) and 25 cm (validated flux, resolved events) from the neutron generator frontal surface.
Simulation: GEANT4 Monte-Carlo simulations (v4.11.0.0) were performed using the NRESP71 model to understand neutron interaction channels, including elastic, inelastic, and the critical ¹²C(n,n’)3α reaction.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-purity, custom-engineered sCVD diamond required to replicate, extend, and optimize the high-flux neutron detection research performed in this study.

Applicable Materials

To achieve the high spectroscopic resolution (13 keV FWHM) and fast timing demonstrated, the highest purity material is essential.

Optical Grade Single Crystal Diamond (SCD): This material is required to minimize defects and charge trapping, ensuring the high charge collection efficiency necessary for superior energy resolution in high-flux environments.
Custom Thickness SCD: The paper utilized 140 µm thickness. 6CCVD offers SCD plates with precise thickness control from 0.1 µm up to 500 µm, allowing researchers to tune the active volume for optimal energy deposition of specific reaction products (e.g., ¹²C(n,n’)3α products).

Customization Potential

The success of this research hinges on precise material dimensions and electrode engineering. 6CCVD provides comprehensive in-house customization capabilities.

Research Requirement	6CCVD Solution & Capability	Technical Advantage
Custom Dimensions	Plates/Wafers up to 125mm (PCD) & Custom SCD Cutting	We can supply the specific 10 mm² detector area used, or larger arrays for improved counting statistics, using advanced laser cutting services.
Electrode Material	In-House Custom Metalization (Ti, Au, Pt, Pd, W, Cu)	The paper used a 100 nm Titanium (Ti) electrode. 6CCVD offers internal deposition of Ti and other metals, ensuring low-resistance ohmic contacts and precise control over the detector dead layer thickness.
Surface Quality	Precision Polishing (Ra < 1nm)	Our SCD material can be polished to an atomic-scale roughness (Ra < 1nm), minimizing surface defects that could contribute to noise or charge trapping, especially critical for fast timing applications.
Global Logistics	Global Shipping (DDU/DDP)	We ensure reliable, fast delivery of sensitive diamond detectors worldwide, simplifying procurement for international research facilities like SARAF.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing CVD diamond properties for extreme environments and complex nuclear physics applications.

Material Selection for Neutron Monitoring: Our experts can assist in selecting the optimal SCD thickness and crystal orientation to maximize the signal-to-noise ratio for high-rate neutron flux monitoring, particularly in the vicinity of strong accelerator sources.
TOF Optimization: We provide consultation on material specifications (e.g., thickness and electrode design) to achieve the sub-nanosecond time resolution required for future Time-of-Flight (TOF) tagging counters in nuclear physics experiments.
BDD for Alternative Applications: While this paper focused on SCD, 6CCVD also offers Boron-Doped Diamond (BDD), which is highly relevant for thermal and epithermal neutron detection (via ¹⁰B(n,α)⁷Li reaction), offering a complementary solution for broad-spectrum neutron facilities.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We have tested the performance of spectroscopic single-crystal Chemical Vapor-Deposited (sCVD) diamond detectors with radioactive sources and with a pulsed deuterium-tritium neutron generator. The tests demonstrate that the detectors could provide good timing and spectroscopic information at high neutron fluxes. The spectroscopic information can be obtained at a 14 MeV neutron rate as high as 1010 n/cm2/s, despite some limitations associated with pulse character of the used neutron generator. Monte-Carlo simulations were performed in order to achieve better understanding of neutron interaction with the detector material. Possible applications for the use of the detectors at Soreq Applied Research Accelerator Facility (SARAF) are considered. The detectors could be used as reliable neutron rate monitors in the vicinity of a strong accelerator-based source of energetic neutrons. The detectors could also be utilized as time-of-flight tagging counters in nuclear physics experiments under condition of high neutron fluxes during short beam pulses. In particular, measurement of the 12C(n,n′)3α cross-section is discussed.

Tech Support

Original Source

DOI: https://doi.org/10.3390/particles8030075

References

2004 - A Fast Low-Noise Charged-Particle CVD Diamond Detector [Crossref]
2006 - Radiation hard diamond sensors for future tracking applications [Crossref]
2011 - Experimental response functions of a single-crystal diamond detector for 5-20.5 MeV neutrons [Crossref]
2016 - Ionization signals from diamond detectors in fast neutron fields [Crossref]
2016 - 13C(n,α0)10Be cross section measurement with sCVD diamond detector [Crossref]
2018 - Upgrade of the compact neutron spectrometer for high flux environments [Crossref]