Study of low multiplicity electron source LEETECH with diamond detector

At a Glance

Metadata	Details
Publication Date	2017-02-16
Journal	Journal of Instrumentation
Authors	Viacheslav Kubytskyi, V. Krylov, P. Bambade, B. Cabouat, F. Wicek
Institutions	Université Paris-Sud, Centre National de la Recherche Scientifique
Citations	2
Analysis	Full AI Review Included

Low Multiplicity Electron Detection using Single Crystal Diamond

This technical documentation analyzes the findings of Kubytskyi et al. (2017) regarding the calibration of the LEETECH low-multiplicity electron source using a diamond detector. The results demonstrate the critical role of high-purity Single Crystal Diamond (SCD) in high-resolution particle detection and beam-line diagnostics.

Executive Summary

Core Achievement: The study successfully utilized a Single Crystal CVD Diamond (SCD) detector to clearly resolve the energy deposition peaks corresponding to 1, 2, and 3 electrons traversing the detector simultaneously.
Application: This technique is validated for high-precision calibration of diamond detectors and for diagnostics of accelerated beam halos in low-multiplicity regimes (down to a few particles).
Material Specification: The detector consisted of a high-purity SCD wafer, 500 µm thick, with Ti/Pt/Au metalization, proving the viability of MPCVD diamond in demanding accelerator environments.
Performance: The detector successfully measured Poisson-distributed electron samples (2.5-3 MeV) and showed a Most Probable Value (MPV) collected charge of 2.88 fC for a single minimum ionizing particle (MIP) electron.
Resolution Challenge: While discrimination was achieved, limited detector resolution was attributed to the Landau distribution of energy deposition in thin detectors, highlighting the need for ultra-low noise amplification systems.
6CCVD Value: 6CCVD specializes in manufacturing the high-quality, custom-dimensioned SCD and advanced metalization required to replicate and advance this precision particle detection work.

Technical Specifications

The following parameters summarize the detector material and performance metrics achieved in the low-multiplicity detection mode.

Parameter	Value	Unit	Context
Diamond Material	Single Crystal CVD (SCD)	N/A	High-purity detector grade
Diamond Thickness	500	µm	Used for single-electron resolution
Detector Dimensions	4 x 4	mm²	Lateral size of the active sensor area
Metalization Layers	Ti/Pt/Au	N/A	Used for top and bottom contacts
Electron Energy (Sample)	2.5 - 3	MeV	Energy of electrons clearly resolved
Energy Deposition (Single Electron MPV)	225	keV	Energy deposited in the 500 µm diamond
Collected Charge (Single Electron MPV)	2.88	fC	Measured charge for single electron event
Magnetic Field (Dipole)	400	G	Field used to select 2.7 MeV electrons
Detector Ionization Yield	36	electron hole pairs / µm	Intrinsic property of the diamond material
Efficiency Parameter ($\alpha_{corr}$)	0.12 ± 0.04	N/A	Corrected efficiency accounting for beam size and alignment

Key Methodologies

The following is an ordered summary of the primary experimental and simulation steps used to achieve low-multiplicity electron detection:

Beam Generation: PHIL photoinjector generated electron bunches accelerated to 3.5 MeV.
Energy Degradation: The beam was passed through an Aluminum attenuator (2 mm thickness used experimentally) to introduce momentum and angular spread.
Spectrometer Function: A magnetic dipole field (400 G) was used to select and bend electrons, delivering a test sample with a mean energy of 2.7 MeV.
Low-Multiplicity Mode Setup: Low multiplicity operation was achieved by finely adjusting entrance and exit collimator systems, ensuring the delivered particle population followed a Poisson distribution with low mean parameter ($\lambda$ < 5).
Detector Fabrication: A SCD detector (500 µm thick, 4 x 4 mm²) was prototyped with Ti/Pt/Au metalization.
Calibration: The SCD detector was calibrated using a ⁹⁰Sr radioactive source, triggered by a scintillator to filter for non-MIP electrons (E > 1.8 MeV), establishing the single-particle MPV response.
Signal Acquisition: The diamond signal was fed into a low-noise charge sensitive amplifier (4 mV/fC gain) and digitized using a 12-bit, 500-MHz bandwidth digitizer.
Data Analysis: The resulting histogram of measured energy deposition successfully showed distinct peaks corresponding to 1, 2, and 3 incident electrons, alongside the noise peak (0 electrons).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials required to replicate, improve, and scale the low-multiplicity detection techniques demonstrated in this research.

Applicable Materials for Particle Detection

To achieve the single-electron resolution demonstrated, the highest purity diamond material is essential for minimizing charge trapping and maximizing Charge Collection Efficiency (CCE).

Optical Grade Single Crystal Diamond (SCD): This material is the ideal choice. 6CCVD supplies SCD with extremely low nitrogen content, ensuring optimal CCE and minimizing noise, which is critical for resolving low-multiplicity peaks caused by the Landau energy distribution.

Customization Potential

6CCVD’s expertise in custom CVD growth and fabrication directly addresses the specific engineering requirements of this detector:

Detector Requirement (Paper)	6CCVD Capability	Technical Benefit
Material Thickness	SCD from 0.1 µm up to 500 µm	Exact replication of the 0.5 mm thickness used for optimized energy deposition.
Custom Dimensions	Plates/wafers up to 125mm (PCD)	Can provide 4 x 4 mm² detectors via precision laser cutting, or large-area detectors for higher flux or profile monitoring.
Metalization Schema	Internal capability: Au, Pt, Pd, Ti, W, Cu	Exact replication of the Ti/Pt/Au contact layers, ensuring stable, low-resistance ohmic contacts essential for low-noise measurement.
Surface Finish	Polishing to Ra < 1nm (SCD)	High-quality surface finish reduces scattering and optimizes bonding wire adhesion, as utilized in the prototyped sensor design.
Global Logistics	Global shipping (DDU default, DDP available)	Reliable, secure delivery of sensitive materials to accelerator facilities worldwide (e.g., LAL, CERN, KEK).

Engineering Support

6CCVD provides dedicated application support from our in-house PhD material scientists specializing in nuclear and particle physics.

Optimization for Low-Multiplicity Projects: Our team can assist researchers in selecting the optimal diamond substrate (thickness, orientation, and purity) to maximize the signal-to-noise ratio for applications such as Beam Halo Diagnostics and Beam Loss Monitoring, ensuring peak resolution in the single-to-few particle regime.
Metalization Design: Consultation on contact placement and material stack optimization (e.g., choice between Au, Pt, or Ti adhesion layers) to interface with specific charge sensitive amplifiers (like CIVIDEC C6).

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

View Original Abstract

In this paper, we present experimental and numerical studies of the calibration of low-multiplicity electron source using signals from electrons incident on a diamond detector. The experiments were performed at the newly commissioned versatile LEETECH platform at the PHIL photoinjector facility at LAL. We show that with a single crystal CVD diamonds of 500 micrometers thickness, the energy losses from the first three electrons of 2.5-3 MeV are clearly resolved. The described technique can be used as a complementary approach for calibration of diamond detectors as well as for diagnostics of accelerated beam halos in a regime down to a few particles.

Tech Support

Original Source

DOI: https://doi.org/10.1088/1748-0221/12/02/p02011