Plastic Scintillator Neutron Detection via Coincidence Timing
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Solution Overview
Problem
Current neutron measurement stations face high costs due to the prohibitively expensive helium-3 proportional counters, and alternative detectors like boron trifluoride and organic scintillators are either toxic, flammable, or inefficient for high counting rates, making them unsuitable for characterizing nuclear materials effectively.
Innovation Solution
A radiation detection method using polyvinyl-toluene (PVT) or polystyrene plastic scintillators not doped with neutron absorbers, arranged around a radiation source, which detects pulse coincidences of multiplicity 2 or higher and employs time difference windows to differentiate between neutron and gamma radiation signals, thereby isolating useful fission coincidences from parasitic ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helium-3 proportional counters are used for neutron detection, then detection efficiency for thermalized neutrons is improved, but cost increases prohibitively
Solution Approach 1:
The patent replaces expensive helium-3 counters with cheaper plastic scintillator detectors that can be used in large numbers without significant degradation, effectively using inexpensive substitute components to achieve the same detection function
Solution Approach 2:
The patent changes the detection parameter from direct thermal neutron counting (helium-3) to fast neutron detection through time-correlated coincidence counting, allowing the use of different detector materials with different properties
2Quantity of substance
If boron trifluoride meters are used as alternative detectors, then cost is reduced, but detection efficiency is approximately 2 times lower than helium-3 counters
Solution Approach 1:
The patent combines multiple low-efficiency detectors in a coincidence counting arrangement, where the joint detection of two or more neutrons from fission events provides superior measurement capability that compensates for individual detector inefficiency
Solution Approach 2:
The plastic scintillator detectors serve multiple functions: detecting fast neutrons directly, providing timing information for coincidence counting, and enabling gamma-ray rejection through pulse shape discrimination
3Quantity of substance
If organic scintillators are used for neutron detection, then cost and availability are improved, but ability to discriminate neutrons from gamma radiation deteriorates
Solution Approach 1:
The patent performs preliminary time-correlation analysis by recording arrival times of all detected particles and subsequently identifying coincidence events through computational processing, separating neutron signals from gamma background before final analysis
Solution Approach 2:
The patent introduces time correlation as an intermediary parameter that mediates between the raw detector signals and the final neutron identification, using temporal patterns to distinguish neutron coincidences from gamma radiation
4Measurement precision
If multiple detectors are arranged around radiation source for coincidence detection, then detection capability is improved, but system complexity increases
Solution Approach 1:
The patent divides the detection system into independent modular detector units, each processing signals locally, with results combined through simple coincidence logic, allowing scalable configuration without proportional increase in overall system complexity
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
This approach effectively reduces the cost and improves the signal/noise ratio by accurately distinguishing between fission and parasitic coincidences, enabling efficient detection of neutrons from fission events while minimizing false positives from gamma radiation and crosstalk interactions.
Implementation Method 1
A radiation detection method using polyvinyl-toluene (PVT) or polystyrene plastic scintillators
Implementation Method 2
each detector comprising a photomultiplier associated with an organic plastic scintillator
Data Source
Figure 1~2
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Figure 5
AI summary
A method for detecting radiation, comprising the steps, implemented by a computer connected to N detectors (N≥3) arranged around a radiation source, each comprising a photomultiplier of: detection, within a time window, of coincidences of pulses of multiplicity of order ≥2 between the electrical signals provided by the photomultipliers; determination of a first number of pulse coincidences for a first time gap window including the pairs (γ, n) and (n, n), and excluding pairs (γ, γ); determination of a second number of pulse coincidences for a second time gap window chosen to include pairs (n, n) and excluding pairs (γ, γ) and (γ, n); counting the coincidences located in a time zone delimited by the first and second time gap windows.