Temporal Gating for Fissile Material Elemental Analysis
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Solution Overview
Problem
Conventional techniques for determining the elemental composition of samples containing fissile materials are time-consuming and require a laboratory setting, and active neutron interrogation methods face difficulties in isolating inelastic pre-fission gamma rays due to the production of delayed gamma rays.
Innovation Solution
A system utilizing a pulsed neutron generator and a detector, synchronized by an analyzer circuit, which defines time bins to distinguish between different types of gamma rays emitted from a sample, allowing for real-time and in situ analysis of elemental composition by assigning pulses to specific time windows and removing 'noise' from delayed gamma rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional techniques are used to determine elemental composition of fissile materials, then measurement precision is maintained, but analysis time becomes excessively long and laboratory environment is required
Solution Approach 1:
The patent employs periodic pulsed neutron generation with temporal gating, where neutrons are emitted in periodic pulses and detection is gated to specific time windows within each pulse cycle. This periodic action enables rapid sequential measurement of different gamma ray components (prompt vs delayed), achieving real-time elemental analysis without requiring lengthy conventional processing or dissolution procedures
Solution Approach 2:
The system performs preliminary temporal gating setup and synchronization before actual measurement begins. The analyzer circuit is pre-configured with time bins corresponding to prompt gamma ray windows and delayed gamma ray windows, allowing immediate real-time analysis upon neutron pulse initiation, eliminating the need for time-consuming sample preparation and sequential measurement steps
2Productivity
If active neutron interrogation is used to analyze samples, then real-time analysis capability is achieved, but delayed gamma rays interfere with isolation of inelastic pre-fission gamma rays
Solution Approach 1:
The detection time window is segmented into distinct temporal bins: prompt gamma ray windows immediately following neutron pulses, and delayed gamma ray windows during inter-pulse periods. This time-based segmentation allows separate measurement and analysis of prompt inelastic pre-fission gamma rays without contamination from delayed gamma rays, achieving both real-time capability and spectral isolation
Solution Approach 2:
By using periodic pulsed neutron generation with duty cycles (e.g., 25% on-time, 75% off-time), the system creates periodic opportunities to measure prompt gamma rays during neutron emission and inter-pulse periods, while measuring delayed gamma rays during off-periods. This periodic measurement strategy enables mathematical separation and precise isolation of prompt inelastic pre-fission gamma ray signals from delayed gamma ray backgrounds
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
Enables rapid, real-time acquisition of elemental composition data from fissile materials, potentially within seconds or minutes, facilitating applications such as airport screening and oil well logging by isolating and identifying elemental signatures through temporal gating of neutron pulses.
Implementation Method 1
gamma rays produced from inelastic neutron scattering reactions
Implementation Method 2
gamma rays produced from thermal neutron capture reactions
Implementation Method 3
prompt fission gamma rays
Implementation Method 4
the detector outputs signals based upon the gamma rays that impinge upon the material, wherein the signals are indicative of energies of the gamma rays
Data Source
AI summary
Technologies related to determining elemental composition of a sample that comprises fissile material are described herein. In a general embodiment, a pulsed neutron generator periodically emits bursts of neutrons, and is synchronized with an analyzer circuit. The bursts of neutrons are used to interrogate the sample, and the sample outputs gamma rays based upon the neutrons impacting the sample. A detector outputs pulses based upon the gamma rays impinging upon the material of the detector, and the analyzer circuit assigns the pulses to temporally-based bins based upon the analyzer circuit being synchronized with the pulsed neutron generator. A computing device outputs data that is indicative of elemental composition of the sample based upon the binned pulses.