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Characterization and Comparison of New Concepts in Neutron

Detection

Advisers:Professor Martin E. Nelson – Mechanical

Engineering

Professor Svetlana Avramov-Zamurovic – Systems Engineering

CAPT Charles B. Cameron – Electrical Engineering

Professor James F. Ziegler – Physics

MIDN 2/C Kayla J. Sax

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Overview

• Objective• Related Work and Support• Background• Method• Analysis• Applications• Contribution• Questions

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Objective

• Premise• Objective: Evaluate both

unmodified and modified memory chips for sensitivity to neutrons, comparing them to conventional detection systems, in an effort to establish their potential for general scientific use.

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Naval Research Laboratory: Related Work and Support

• Naval Research Laboratory (NRL)– Point of contact: Dr.

Harold Hughes, Solid State Devices Branch

• Developing device to be utilized for remote detection of nuclear weapons of mass destruction (WMDs).

• Supporting and funding project.

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Neutron Detection System Applications

• Hospitals and Health physics• Nuclear power plants • International nuclear weapons

treaty compliance• Homeland security• Military

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Conventional Neutron Detection Systems

• Non-powered– Thermoluminescent dosimeter (TLD)– Foil activation detector– Bubble detector– Track-etch detector

• Powered– BF3 proportional counter

– 3He proportional counter

Lithium Fluoride Crystals

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Conventional Neutron Detection Systems

• Non-powered– Thermoluminescent dosimeter (TLD)– Foil activation detector– Bubble detector– Track-etch detector

• Powered– BF3 proportional counter

– 3He proportional counter

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Conventional Neutron Detection Systems

• Non-powered– Thermoluminescent dosimeter (TLD)– Foil activation detector– Bubble detector– Track-etch detector

• Powered– BF3 proportional counter

– 3He proportional counter

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Conventional Neutron Detection Systems

• Non-powered– Thermoluminescent dosimeter (TLD)– Foil activation detector– Bubble detector– Track-etch detector

• Powered– BF3 proportional counter

– 3He proportional counter

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Conventional Neutron Detection Systems

• Non-powered– Thermoluminescent dosimeter (TLD)– Foil activation detector– Bubble detector– Track-etch detector

• Powered– BF3 proportional counter

– 3He proportional counter

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Conventional Neutron Detection Systems:

Advantages and Disadvantages• Non-powered

– Advantages:• Require no external energy source and therefore can

operate in almost any environment.• Relatively inexpensive compared to more complicated

powered detectors. – Disadvantages:

• Passive; provide the user no instantaneous information.

• Powered– Advantages:

• Active; provide information on radiation exposure more quickly and more often.

– Disadvantages:• Require a significant amount of power, operating at

900V – 1500V.

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Detection Methods Based on Integrated Circuit

Components • Conventional detection systems that

rely on integrated circuit components: – Direct Ion Storage (DIS) Dosimeter – Metal Oxide Semiconductor Field Effect

Transistor (MOSFET) Dosimeter

• No neutron detection system relying on memory cells is currently competitive with other detectors.

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Utilizing Static Random Access Memory (SRAM) for Neutron

Detection • Metric: Soft Error Rate (SER)• Theory: Technological advances

and their result on SER trends.• Result: An SRAM chip with a

high SER makes an inferior memory device but an excellent neutron detector.

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Unmodified Chip

Typical Unmodified Memory Chip Dimensions (Cross-Section)

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Sensitivity-Enhancing Modification of Chips

Modified Memory Chip (Cross-Section)

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Sensitivity-Enhancing Modification of Chips

Modified Memory Chip (Isometric View)

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Method for Evaluation of SRAM Sensitivity

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Summary of Experimental Plan

Detector Comments Output Incident EnergiesTested

FluencesTested

TLD Non-powere

d

Electrical Charge

4 3

Foil Activation Non-powere

d

Counts 4 3

Bubble Detector

Non-powere

d

Bubbles 4 3

Track-etch Detector

Non-powere

d

Tracks 4 3

BF3 Proportiona

lCounter

Powered Pulses 4 3

3He Proportiona

lCounter

Powered Pulses 4 3

UnmodifiedMemory Chip

Ultra-lowPowered

SER 4 3

Modified MemoryChip

Ultra-lowPowered

SER 4 3

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Detector Comments Output Incident EnergiesTested

FluencesTested

TLD Non-powere

d

Electrical Charge

4 3

Foil Activation Non-powere

d

Counts 4 3

Bubble Detector

Non-powere

d

Bubbles 4 3

Track-etch Detector

Non-powere

d

Tracks 4 3

BF3 Proportiona

lCounter

Powered Pulses 4 3

3He Proportiona

lCounter

Powered Pulses 4 3

UnmodifiedMemory Chip

Ultra-lowPowered

SER 4 3

Modified MemoryChip

Ultra-lowPowered

SER 4 3

Summary of Experimental Plan

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Detector Comments Output Incident EnergiesTested

FluencesTested

TLD Non-powere

d

Electrical Charge

4 3

Foil Activation Non-powere

d

Counts 4 3

Bubble Detector

Non-powere

d

Bubbles 4 3

Track-etch Detector

Non-powere

d

Tracks 4 3

BF3 Proportiona

lCounter

Powered Pulses 4 3

3He Proportiona

lCounter

Powered Pulses 4 3

UnmodifiedMemory Chip

Ultra-lowPowered

SER 4 3

Modified MemoryChip

Ultra-lowPowered

SER 4 3

Summary of Experimental Plan

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Neutron Sources Available at USNA

Source Location Incident Neutron Energy

D-T Accelerator RI073 14 MeV

Pu-Be Sources (5) RI005 4 MeV

D-D Accelerator RI073 2 MeV

SCR RI005 Thermal

USNA D-T Neutron Generator in Exposure Room

USNA D-D Neutron Generator

USNA Sub-Critical Reactor

Pu-Be Source

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Summary of Experimental Plan

Detector Comments Output Incident EnergiesTested

FluencesTested

TLD Non-powere

d

Electrical Charge

4 3

Foil Activation Non-powere

d

Counts 4 3

Bubble Detector

Non-powere

d

Bubbles 4 3

Track-etch Detector

Non-powere

d

Tracks 4 3

BF3 Proportiona

lCounter

Powered Pulses 4 3

3He Proportiona

lCounter

Powered Pulses 4 3

UnmodifiedMemory Chip

Ultra-lowPowered

SER 4 3

Modified MemoryChip

Ultra-lowPowered

SER 4 3

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Analysis

• Sensitivity of each detection system to a particular incident neutron energy established.

• Confidence level for each sensitivity determined.

• Minimum dose sensitivity and dose saturation level established.

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Special Application: Screening Cargo Containers

for WMDs • NRL scheduled to produce three

additional devices.• Pending successful production,

NRL has asked to collaborate with me to extend my research into evaluating the group of new devices.

• Expansion of work into developing a new system of nuclear WMD monitors for cargo containers.

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Timeline• 2/C Spring Semester

– Take Reactor Physics I (EM362)– Conduct additional background research

• 1/C Summer– Participate in University of Florida Internship– Order bubble detectors and track-etch detectors– Obtain unmodified/modified chips and tester from NRL

• 1/C Fall Semester– Ensure operational status of detection systems– Cross-calibrate TLD, bubble, and track-etch detectors

against foil activation with 14 MeV source– Test, analyze, and evaluate all detectors with 14 MeV

source– Write interim report

• 1/C Spring Semester– Test, analyze, and evaluate all detectors with remaining

sources– Conduct complete comparative analysis– Write and present final Trident Scholar report– Present final results at a technical conference

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Contribution

• Characterization of a brand new concept in neutron detection.

• Establish the potential for detection system to improve existing applications.

• Establish the potential for detection system to be implemented as a remote special nuclear material detection system in cargo containers.

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Characterization and Comparison of New Concepts in Neutron

Detection

Advisers:Professor Martin E. Nelson – Mechanical

Engineering

Professor Svetlana Avramov-Zamurovic – Systems Engineering

CAPT Charles B. Cameron – Electrical Engineering

Professor James F. Ziegler – Physics

MIDN 2/C Kayla J. Sax