Neutron Detector with Boron-Lithium Scintillator Layer

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Solution Overview

Problem

Existing neutron detection technologies using gadolinium or cadmium struggle with discrimination in high-energy gamma environments and fail to provide accurate neutron dose measurements, limiting their effectiveness in industrial and safety applications.

Innovation Solution

A neutron detector system comprising a gadolinium or cadmium core surrounded by a scintillating plastic shell, with an additional scintillator layer containing boron or lithium, and employing pulse shape discrimination and pseudo-spectral modeling for enhanced sensitivity and robustness against gamma radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gadolinium or cadmium is used for neutron detection, then neutron capture efficiency is improved, but discrimination capability in high-energy gamma environments deteriorates

Engineering Contradiction:
Improveneutron detection efficiencyVSAvoidgamma radiation interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The detector is segmented into multiple functional layers: a central gadolinium or cadmium core for neutron capture, surrounded by a plastic scintillator shell for gamma detection, and an outer scintillating coating containing boron or lithium for additional neutron capture. This segmentation allows each layer to contribute to neutron detection while the plastic scintillator shell provides gamma discrimination capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The detector employs a composite structure combining gadolinium or cadmium (for high neutron capture cross-section) with plastic scintillator material (for gamma discrimination) and boron or lithium coating (for thermal neutron detection). This composite approach enables simultaneous neutron detection efficiency and gamma radiation discrimination.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If radiative capture of gadolinium is used, then neutron capture signal is enhanced, but measurement reliability in high-energy gamma atmosphere deteriorates

Engineering Contradiction:
Improvecapture signal intensityVSAvoidmeasurement reliability in gamma environment
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

Different regions of the detector have specialized functions: the gadolinium or cadmium core provides strong capture signals, the plastic scintillator shell provides gamma discrimination through its response characteristics, and the boron or lithium coating enhances thermal neutron detection. This local specialization allows the system to maintain reliability in gamma environments while preserving capture signal intensity.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If existing gadolinium-based detection techniques are used, then neutron detection capability is improved, but neutron dose measurement capability deteriorates

Engineering Contradiction:
Improveneutron detection capabilityVSAvoidneutron dose measurement capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The detector is designed to perform multiple functions: it detects thermal neutrons through gadolinium or cadmium capture, detects fast neutrons through the plastic scintillator response, and can estimate neutron dose by analyzing the combined signals from different layers. This multi-functionality enables both neutron detection and dose measurement capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system achieves isotropic, economically competitive, and transportable neutron measurement capabilities, enabling accurate radiological dose assessment even in challenging gamma environments, surpassing the limitations of previous technologies.

Implementation Method 1

Inside a suitably sized plastic scintillator, these rays can lead to an energy deposition on the order of 3 MeV to 4 MeV, or even higher

Methodology Applied
Scientific EffectScintillation: Scintillation

Implementation Method 2

the slowing down of incident neutrons by the sphere

Methodology Applied
Scientific EffectThermalization:

Implementation Method 3

Gadolinium and cadmium exhibit the largest neutron capture cross-sections among stable isotopes

Methodology Applied
Scientific EffectNeutron capture:

Implementation Method 4

a thin scintillation coating that exploits neutron capture by boron or lithium

Methodology Applied
Scientific EffectNeutron capture by boron or lithium:

Data Source

PatentEP3452850B1Neutron detector, with scintillating plastic, surrounding a gadolinium or cadmium core, and scintillating cover doped or covered by boron or lithium, and associated neutron counting device
Publication Date: 2020.06.10 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3452850B1 patent drawingFigure 1~2
  • EP3452850B1 patent drawingFigure 3~4
  • EP3452850B1 patent drawingFigure 5~6

AI summary

The invention relates to a neutron detector, with scintillating plastic, surrounding a gadolinium or cadmium core, and a scintillating cover doped or covered by boron or lithium, and associated neutron counting device. The neutron detector comprises a core (2), which is rich in gadolinium or cadmium, a shell (10) made of a plastic scintillator, which surrounds the core, and a photon-conversion device (16) which has an interface with the shell and which converts the scintillation photons from the shell into a signal representing same. According to the invention, the detector also comprises a scintillator layer (12) containing boron or lithium, which surrounds the shell. The counting device comprises the detector and a device (20) for processing a neutron counting signal from a signal representing scintillation photons. The invention can be used, in particular, for dose rate measurements.