Explosives Trace Detection - ndiastorage.blob.core ... · Susan Hallowell, Ph.D. Director...

Susan Hallowell, Ph.D.Susan Hallowell, Ph.D.DirectorDirectorTransportation Security LaboratoryTransportation Security LaboratoryScience and Technology DirectorateScience and Technology DirectorateDepartment of Homeland SecurityDepartment of Homeland Security

Explosives Trace DetectionExplosives Trace Detection

““Putting First Responders FirstPutting First Responders First””

Science & Technology

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Susan F. Hallowell, Ph.D. January 14, 2008

Explosives and Weapons Detection‘Bulk and Trace’ Programs

Bulk

Trace

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Trace Detection

Can be solid (particulate) or gas (vapor) phase.ppm, ppb, or even ppt

Identifies explicit composition

TATP

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Explosives Detection Overview Trace Detection – Chemistry Approaches

Detection of trace (<ng/ppb) levels of explosive particles andvapors resulting from contamination

C-4 particle on cloth at 400X

Vapor signature

Vapor molecule of TNT

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Trace Detection - What are we finding?n 1-100 Nanogram of residue

n On the Concealment (BOMB)

n

On the Latches, Handles, etc (bags,

cargo, vehicles, people, ...)

n On the Interior of the Surfaces

n On the Exterior of the Surfaces

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Where does the Traces of Explosives Come From ?n Contact with the Bulk Explosive

n Aerosolized Explosive

n Secondary Fingerprints

n

Contact with Contaminated Hands

(gloves)

n Contact with Surfaces - Tools & Workplace

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Explosives Matter

Explosives Industrial Chemicalswhich can form Explosive Mixtures

Ammonium NitrateSodium Chlorate

Organic PeroxidesNG, PETN (Medical Use)Solid Fuel (camp Stoves)

Primary(initiating)

Secondary

MilitaryExplosives

IndustrialExplosives

DynamitesPermitted Explosives

ANFOSlurries Emulsions

Binary

TNTRDXHMXPETNPBX-*

Boosters

Lead AzideLead StyphnateMercury Fulinate

Tetryl

Propellants

GunPropellants

RocketPropellants

SmokelessBlack Powder

Double BaseTriple Base

Liquid

High Explosives Pyrotechnics

FlashesFlares

Noise GeneratorsSmokes

Fireworks

Characteristics of Explosives• Detonation velocity• Intimacy of fuels• Sensitivity to external stimuli

Explosives Detection Overview Classification of Explosives

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ExplosivesStandard ExplosivesStandard Explosives

TNTTNTRDXRDXPETNPETNNitroglycerin (NG)Nitroglycerin (NG)Ethylene Glycol Ethylene Glycol DinitrateDinitrate (EGDN)(EGDN)

Plastic ExplosivesPlastic ExplosivesCC--4 (RDX)4 (RDX)DetasheetDetasheet (PETN)(PETN)SemtexSemtex (RDX + PETN)(RDX + PETN)

Improvised ExplosivesImprovised ExplosivesANFO (Ammonium nitrate + fuel oil)ANFO (Ammonium nitrate + fuel oil)Urea nitrate Urea nitrate TriacetoneTriacetone triperoxidetriperoxide (TATP)(TATP)

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Explosive Compounds

H2C

CH2

CH2

NO2

NO2NO2

RDX

C

CC

O

OO

H

H

HH

H

NO2

NO2

NO2

NG

CCH2

H2C CH2

H2C O

OO

O NO2

NO2

O2N

O2N

PETN

CH3NO2NO2

NO2

TNT

NH2NO2NO2

NO2

NH2H2N

TATB

H2C CH2

CH2H2C

NO2

NO2NO2

NO2

HMX

CC

C

C O

C

OC

C

C C

CO

OO ONO2

ONO2

ONO2

ONO2

H H

HONO2

H

H ONO2

H H

H

HH

nNitrocellulose

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0 50 100 150 200 250 300 350Molecular Weight [amu]

Con

cent

ratio

n in

Air

at 2

5 C

HMX

1 ppm

1 ppq

TATPEGDN

p-MNTNG

DMNB

DNT

AN TNT

PETNRDX1 in 1012

1 ppb

1 ppt

1 in 109

1 in 106

1 in 1015

1 in 103

*Cocaine

Ref: US DOE study . . .

Vapor Pressure, at Room Temperature . . .

Trace Detection: Three processes- Collect - the sampling process…Front-end

collection / preconcentration…

- Separate - provides selectivity of threat…

- Detect - provides sensitivity for the threats of interest…

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Particle vs. Vapor SamplingParticle vs. Vapor Sampling

- Most threats only provide spread via particles…* exceptions - newer homemade threats…

- Particle - hard, solid surfaces; contact swiping- soft surfaces, air jet or vac. sampling

- Vapor - High and low volume air collection.

- Today - need for both, simultaneous…

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C-4 Fingerprint

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X-RAY MAPPING OF C-4

X-ray Nitrogen MapSEM of C-4 on Muslin

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Particle SamplingParticle Sampling- How to remove from surfaces;

- First, need to know physical and chemical properties of the threat of interest … particle size, stickiness, binding forces, vapor pressure, etc.

- Sample Swiping method - efficiency of collection; careful selection of material, collection via hand wiping or sampling wand, area per collection and pressure to be applied, etc..-Enviromental effects; dry vs. wet surface (vs. type of sample swipe), clean vs. dirty surfaces, etc.

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Reference herein to any specific commercial products, processes, equipment, or services does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or the Department of Homeland Security (DHS), or any of its employees or contractors.

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Commercial Trace Sampling Wands

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Smiths Detection

IonScan 400B

GE-Ion Track

Itemiser2

Explosives Detection Overview Trace Detection – Deployed Particle Equipment

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Vapor SamplingVapor Sampling- How to collect from surfaces; - First, need to know physical and chemical properties of the threat of interest … vapor pressure, sublimation rate, etc. --------->>>- Sample method - efficiency of collection; careful selection of collection via low volume or high volume sampling, distance to suspect item critical, etc.-Enviromental effects; temperature (range of temp), clean vs dirty surfaces (amount of other non-threat vapor), etc.

Sampling for Explosive Vapors

Human Convection PlumeThe ITMS Detector

0∂

=∂

i

i

Ux

2

3 2

ˆ 1Re

i i ij i j i

j i j j j

U U Up GrU u ut x x Re x x x

δ∂ ∂ ∂∂ ∂+ = − + − + Θ

∂ ∂ ∂ ∂ ∂ ∂

Reynolds Averaged Navier-Stokes

Laser Sheet Flow VisualizationScalar Flow Model

–A New Hypothesis

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Smiths Detection

Sabre 4000

GE – IonTrack

VaporTracer2

Explosives Detection Overview Trace Detection – Vapor Detection Equipment

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Smiths Detection

Sentinel

Syagen

Guardian

GE – IonTrack

EntryScan3

Explosives Detection Overview Trace Detection – Whole Body Screening

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Explosives Detection Overview Trace Detection – Canines

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Vortex Sampling System

Axial cyclone with return flow designed to generate an artificial tornado and pick up vapors of explosive materials without physical contact with a surface.

Sampling distance is ½"-13½".

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Trace Explosive Detection Technologies

Electronic/Chemical: Picogram sensitivityIon Mobility Spectrometry : Widespread use: Separates and Analyzes in secondsChemiluminescence: Extremely sensitive, need to separate explosives from other compoundsElectron Capture Detection: Sensitive, but needs separation stepSurface Acoustic Wave: Trade off between specificity and sensitivityThermo-Redox: Sensitive, needs separation stepMass Spectrometry: Requires high vacuum, is fragile but very sensitive

Colorimetric (Chemical): Sensitive only to micrograms to nanograms

BiosensorK-9s: Sensitive, versatile, must train to application Antigen Antibody: Very sensitive, but very specific

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Technology RequirementsMeet Detection Specification for Sensitivity and Selectivity forSpecified Threats.

Very Low False Alarm Rate

Very High Probability of Detection

Minimal Decision Making by Human

Automated

Robust

Can Be Operated by Screeners (Not the Ones That Have a Masters Degree in Physics)

Not Too Expensive (ETD, consumables, etc.)

Privacy Concerns Addressed

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BARRINGERTechnology - Ion Mobility Spectrometry

Approved models - IonScan Models 400 and 400B

IONTRACKTechnology - Ion Mobility Spectrometry

Approved models - Itemizer-DOS & Itemizer-W

THERMODETECTIONTechnology - GC/Chemiluminescense

Approved models - EGIS Models 3000 & II

Deployed Trace DetectorsDeployed Trace Detectors

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ION MOBILITY SPECTROSCOPYION MOBILITY SPECTROSCOPY (IMS)(IMS)

Applications:•Explosives detection on both luggage and people•Detection of narcotics

Technical Barriers:•Dependent on screener sampling•Susceptible to atmospheric changes•Calibration requirements•Saturation possible

•Substrate heated to vaporize particles•Molecules are ionized by a weak radioactive source and drift through a weak electric field•Particle time of flight is a distinct fingerprint, enabling detection

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ITMS DetectorHow It Works

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Simultaneous, Dual-Mode Detector

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Challenges to Trace DetectionInterferential OnlyAn alarm does not necessarily mean a bomb if sampling for particles but you need a good reason to be

contaminated! If you see vapor, YOU HAVE A BOMB!

SamplingTrue vapor and particle sampler does not exist

Its about getting the sample!!

Currently highly dependent on skilled operator

Selectivity/SensitivityA wider range of threats (cross-applications) needs to be addressed and developed for Trace Detection, eg. Chemical agents, transparent Extremely sensitive explosive detectors exist, but ability to detect more compounds, lower false alarm rate needed.

Operational alarm rates are “reasonable” for many of the current applications; but are prohibitively high in others.

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Explosive Trace Detectors The Future …

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Near – term ETD’s . . . and improvements to sample collection . . .

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MicroHound III

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separation detectionpreconcentrationcapture

Mini - Ion Mobility Spectrometerdetection

explosives vapors

SAW array

SAW = surface acoustic wave

MicroHound™ Concept

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Microsensors Requirements for Detection of Explosives for First

Responders

Small and portable

Specific to one or more explosives

Array of Sensors – provides full threat coverage, and Improved alarm statistics.

Sensitive (and Selective).

Low cost

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Micro-electromechanical System (MEMS) Cantilever

Ref: T. Thundat et al, ORNL

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Micro-electromechanical System (MEMS) Cantilever

Ref: Coatings NRL & ORNL

ATF /TSAuCantil. Progm.

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Micro-electromechanical System (MEMS)Cantilever detection systemCantilever detection system

T. Thundat et al., Ultramicroscopy, 97, 433, 2003

Is based on miniature microIs based on miniature micro-- machined silicon cantilevers (a few machined silicon cantilevers (a few hundred hundred μμmm long and 1 long and 1 μμmm thick) thick) that can detect tiny forces caused that can detect tiny forces caused by heatby heat--induced induced nanonano--explosions.explosions.The silicon material absorbs the The silicon material absorbs the explosive vapor, which is heated explosive vapor, which is heated and undergoes tiny explosions that and undergoes tiny explosions that are detected by an optical beam.are detected by an optical beam.Scanning the temperature of the Scanning the temperature of the cantilever allows detection of cantilever allows detection of various explosives, according to various explosives, according to their temperature of deflagration.their temperature of deflagration.

SensitivitySensitivity: 10: 10--30 30 pptppt of RDX and of RDX and PETN (PETN (femtogramfemtogram range)range)

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Mass Spec on a Chip/MEMS

R&D of a front end Chemical sensor for the MEMS based MS on a Chip (and support of MS development project).

Report with evaluation of one type of front end chemical sensor (gas centrifuge separator).

Inlet Outlet

Inlet Valve Pump

Outlet Valve

MS on a Chip- Partnership with NG/ARL/DARPA

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What analyte is a detection dog signaling on?

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2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.507.00 7.50 8.00 8.509.00 9.500

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

550000

600000

650000

700000

Time-->

Abundance

TIC: SEMTA31.D

Ab d

4 89

5 31

5 44

6.26

7.30

7.69

8.30

9.04

9.61

Styrene

Ethylbenzene

M-Xylene Nonane

α-pinene

Decane

Ethyl hexanolUndecane

DodecaneTridecane

Time (minutes)

Semtex H Headspace Analysis

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Nano detection on micro systemsCNT – nano explosives Det.

The Future of Trace?

CNT – nano wire sensor

• Automated Samplers: The key is the front end!

Trace Explosives and CW/BW Sensor Development, Metal Detection, etc.

Embedded Detectors in containers/walls.

Nanotechnology: sources and detectors

Effort with NASA Ames Research Cntr.

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Future Prospects

Novel Collection/Sampling Systems, New ETD’s – including other technologies like MS, Spectroscopy (THz, CRDS, ...), etc.

Microsensors/electronic noses – as Array Detectors.

Nanotechnology will become the major driver for microsensors, and certainly a long-term future development.

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Conclusions…• Today/Future - need to efficiently sample both vapor and

particle at same time…

- Automated - to eliminate or reduce human training and human ability to sample.

- Non-contact (if possible) - to reduce interaction with surfaces and eliminate wiping of surfaces (manual sampling issues, cost of consumables, etc.).

• Ability to detect threats with Trace Explosive Detection is a combination of Sampling and Detection…both critical processes.

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Questions?

Susan F. Hallowell, Ph.D.Transportation Security LabScience and TechnologyEmail: [email protected]

mailto:[email protected]

Explosives Trace Detection - ndiastorage.blob.core ... · Susan Hallowell, Ph.D. Director...

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