Solution-Grown Stilbene Crystals for Neutron Detection

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Solution Overview

Problem

The limited availability and high cost of stilbene and other melt-grown crystals for radiation detectors hinder the development of large-crystal scintillators, as they are difficult to obtain through conventional melt growth processes.

Innovation Solution

Growing organic crystals, such as those comprising diphenylacetylene and stilbene or stilbene derivatives, using solution growth methods, which allows for the production of crystals with signal response signatures for neutrons from radioactive sources, including photodetectors for detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If melt growth process is used to produce stilbene crystals, then crystal quality and size are improved, but manufacturing cost and difficulty increase significantly

Engineering Contradiction:

Improvecrystal qualityVSAvoidmanufacturing difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the fundamental growth parameter from melt-based to solution-based growth. This involves dissolving stilbene or diphenylacetylene in appropriate solvents and controlling crystallization through solvent evaporation or temperature changes, thereby avoiding the technical difficulties of melt growth while maintaining crystal quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs inexpensive, readily available solvents and simple evaporation containers instead of expensive, complex melt growth apparatus. The solution growth method uses common laboratory equipment and materials, dramatically reducing manufacturing cost and complexity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If melt growth process is used to produce stilbene crystals, then crystal quality is improved, but production time and accessibility worsen

Engineering Contradiction:

Improvecrystal qualityVSAvoidproduction time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent prepares saturated solutions in advance and allows gradual evaporation to occur over time, producing high-quality crystals without the need for complex real-time control during growth. The preliminary preparation of supersaturated solutions enables controlled, steady crystal formation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The solution growth method allows crystals to form autonomously through natural evaporation or controlled temperature changes, without requiring continuous intervention or complex equipment. The system self-regulates the crystallization process, reducing production time and increasing accessibility

Inventive Principle:

Principle #25Self-service

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 increases access to these materials, reduces their cost, and enables the production of crystals with pulse shape discrimination properties similar to stilbene, facilitating more efficient neutron-gamma differentiation in radiation detection.

Implementation Method 1

Pulse shape discrimination (PSD) of organic scintillators involves subtle physical phenomena which give rise to the delayed luminescence characteristic of neutrons

Methodology Applied

Scientific EffectPulse shape discrimination:

Implementation Method 2

The mechanism by which this occurs begins with intersystem crossing (ISC), where the excited singlet state (S1) nonradiatively relaxes to the excited triplet (T)

Methodology Applied

Scientific EffectIntersystem crossing:

Implementation Method 3

the energy migrates until two triplets collide and experience an Auger upconversion process

Methodology Applied

Scientific EffectAuger upconversion: Auger Effect

Implementation Method 4

Finally, the delayed singlet emission occurs with a decay rate characteristic of the migration rate and concentration of the triplet population

Methodology Applied

Scientific EffectDelayed singlet emission: Fluorescence

Data Source

PatentUS8872125B2Solution-grown crystals for neutron radiation detectors, and methods of solution growth

Publication Date: 2014.10.28 LAWRENCE LIVERMORE NAT SECURITY LLC

AI summary

An organic crystal according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. Methods of making such crystals are also provided.