LUMINESCENCE OF COMMON MATERIALS: APPLICATION TO NATIONAL SECURITY

Adjunct Professor Nigel A. Spooner 1,2

and Dr Barnaby W. Smith 1

1. Defence Science and Technology Organisation&

2. Institute for Photonics and Advanced SensingSchool of Chemistry and Physics

University of Adelaide

Overview:

Luminescence Techniques for Defence & National Security

Opportunistic Dosimetry: “New” Luminescence & “New” Materials

Example: Salt

Institute for Photonics and Advanced Sensing (IPAS)– DSTO/University of Adelaide Centre of Expertise in Luminescence

Luminescence Detection of Radiation ExposureLuminescence Detection of Radiation ExposureDoes not rely on the detection of either Ionising Radiation or Radioisotopes - offers a

unique capability in sanitised locations and in the post-event recovery phase

Detection of cDetection of clearedleared ‘‘dirty bombdirty bomb’’ construction or storage sites.construction or storage sites.

•• forensic analysis even when forensic analysis even when free free of isotopic contamination.of isotopic contamination.

Support for UN weapons inspection efforts.Support for UN weapons inspection efforts.•• forensic analysis of bunkers, buildings forensic analysis of bunkers, buildings

and laboratories cleaned and refurnished and laboratories cleaned and refurnished for nonfor non--nuclear cover activity.nuclear cover activity.

Retrospective population exposure Retrospective population exposure assessment.assessment.

•• measure of measure of extent of the affected areaextent of the affected area..•• quantification of radiation exposure over the quantification of radiation exposure over the

affected areaaffected area

PreventionPrevention DetectionDetection

ResponseResponseRecoveryRecovery

The population of trapped charge is proportional to the absorbed

dose

Conduction Band

radiation

Valence Band

Trap

Ea

thermal oropticalrelease

lightemission

Luminescence MechanismLuminescence Mechanism

- enabling quantitative dosimetry

Principal Steps in Luminescence AnalysisPrincipal Steps in Luminescence Analysis

Environmental radioactivity measurements are alsoEnvironmental radioactivity measurements are alsomade to correct for the natural radiation backgroundmade to correct for the natural radiation backgroundIncluding use of a NaI portable GammaIncluding use of a NaI portable Gamma--ray Spectrometry, hereray Spectrometry, hereundergoing calibration at Geosciences Australia, Canberraundergoing calibration at Geosciences Australia, Canberra

Then measured in the LaboratoryThen measured in the LaboratoryPhotonPhoton--Counting Imaging System at ANUCounting Imaging System at ANU

enables analysis of slices and potential rapidenables analysis of slices and potential rapidassessment of doseassessment of dose--depth profilingdepth profiling

Chemically prepared …

Sample cores are extracted from common building materials at suspect sites…

Retrospective nuclear accident dosimetryRetrospective nuclear accident dosimetry

Art authenticationArt authentication

Detection of illicit food irradiationDetection of illicit food irradiation

Atomic bomb radiation effectsAtomic bomb radiation effects

Chronology of human evolutionChronology of human evolution

Geomorphology & Soil ScienceGeomorphology & Soil Science

MegafaunalMegafaunal extinction/climate changeextinction/climate change

Luminescence TechniqueLuminescence Technique

BUT: requires very experienced personnelBUT: requires very experienced personnel

Numerous reported applications in the open Numerous reported applications in the open literature:literature:

Motivation: Naturally-occurring materials are well-studied

notably quartz and feldspar for luminescence dating

BUT –

these may not be present in many scenarios of interest

urban or industrial locations, vehicles

Instead, Artificial materials may dominate

which ones can reveal prior exposure to ionising radiation?

Many candidate materials exist but few are sufficiently well-studiedto enable rapid use

entails compiling, validating and extending current know-how

The complexity of the phenomena means extensive laboratory work is required to develop Standard Operating Procedures

Extension to “New” Signals and Materials

A Key Goal is the testing and extension of protocols on new A Key Goal is the testing and extension of protocols on new and established materials, to develop Standard Operating and established materials, to develop Standard Operating

Procedures to enable rapid and flexible analysisProcedures to enable rapid and flexible analysis

Example – Analysis of Brick

Schematic diagram illustrating current standardised sectioning used to sample brick for depth-dose measurements

Currently there are no standard protocols, however the Luminescence Dating community has a large and expanding literature on fired and

unfired materials, and increasing effort in Radioepidemiology

Key Goal – Standard Operating Procedures

Dosimetric Materials at Habitations:

Ceramics

Porcelain & tiles

Bricks

Pottery

Mortar & Concrete

Glass

Salt

Hard plastics (some?)

Gyprock

Mud-based insect nests

Carbonate materials (limestone, marble, calcite etc)

Quartz, Feldspar & Zircon grains

Items carried by people, such as:• Glass (spectacles, watches etc)• Jewelry• Credit cards• Electronic components• Hard plastics (some?)• Some foodstuffs

Opportunistic DosimetryUtilisesUtilises materials that fortuitously occur in the incident

environment, or are carried in by peopleContrary to Luminescence Dating, Opportunistic Dosimetry can utilise signals lacking long-term stability.

This eliminates many complications (from ambient environmental radiation and signals of formation), and in the CT context this biases against reporting False Positives

The Potential of Salt (NaCl) For Retrospective Dosimetry

19 samples have been collected from around the world Australia, UK, Poland, USA, Canada etc.

Types include:

Rock salt

Salt damp crystals

Domestic salt from evaporation of: sea water; saline lake water saline river water

Our Analyses have included:1. Emission Spectra2. Kinetic Analysis3. TL Sensitivity Changes During Heating4. OSL & IRSL Dose Response5. OSL & IRSL Pulse-Annealing Spectra6. OSL & IRSL Sensitivity Summary7. Imaged OSL, IRSL, TL

TL Emission SpectraAll samples were measured on the University of Adelaide “3D TL Spectrometer”

No signal-of-formation was observed from any recent-age sample

Representative spectra are shown, measured at 2K/s; 2Gy beta dose

Prominent TL peaks were seen in the mid-Temp range (150-280ºC), with emissions in UV: 380 nm (3.4 eV), Blue: 440 nm (2.8 eV), Red 590 nm (2.1 eV).

(18) JFK Airport, USA (3) Woolworths Homebrand (10) Himalayan Rock Salt

Signal Lifetime: by Variation of Heating Rate Method

0 100 200 3000

5 10 3

0.01

Glow5n

Glow2n

Glow1bn

Glow05bn

Glow02n

Glow01n

Glow005n

Glow002n

Glow001n

Glow0002n

T1Temperature (ºC)

0.1 deg/s

5 deg/s

0.02 deg/s0.01 deg/s

0.002 deg/s

2 deg/s

0.2 deg/s

0.5 deg/s

1 deg/s

0.05 deg/sAre

a N

orm

alis

ed T

L

Sample #3; “Woolworths Homebrand” Salt chosen due to representative glow curve shape and strong Red TL emission

11

12

13

14

15

16

17

18

19

0.0027 0.0029 0.0031 0.0033

1/T

Ln(T

max

2 /B)

0.002 K/s

1.0 K/s

0.02 K/s

0.2 K/s

100ºC peak (5K/sec)Lifetime20ºC = 6.6 hours

200ºC peak (5K/sec)Lifetime20ºC = 0.64 ka

240ºC peak (5K/sec)E= 1.45 eVs= 7.9 x 1013 s-1

Lifetime20ºC = 3.9 ka

Data for 100ºC peak

Heating rates 5 K/s – 0.002 K/s

Sample # Provenance

OSL (after PH 150ºC)(Cts/Gy/mg)(1s shine)

IRSL (after PH 150ºC) (Cts/Gy/mg)*25

(1s shine)

OSL100 sec shine

(Cts/Gy/mg)

11 Salt Damp Crystals | 48 ||| 5159

12 River Murray Salt Flakes (evap.) | 1602 |||||| 595 |||| 7735

1 Australian Lake Salt |||| |||||| ||||||||||||

13 Ramona's salt |||||| |||||| ||||||||||||||

3Woolworth's HomeBrand Salt (evap. seawater) |||||| 11549 ||||||| 771 |||||||||||||| 29861

19 Sydney, Canada (Huston Texas) ||||||| |||| ||||||||||||||

16 Table Salt, UK, Silver Sachet |||||||||||| 26758 ||||||| 1028 |||||||||||||||||| 39637

14 Evap. Seawater ||||||| ||||| ||||||||||||||||||

15Table Salt, UK Roadhouse, Blue Sachet ||||||||||| |||||||||| ||||||||||||||||||

18JFK Airport, USA (Savannah Georgia) |||||||||||| ||||| |||||||||||||||||||||||

20 Halifax Canada ||||||||||||||||| ||||| |||||||||||||||||||||||||||||||

8 Evap. Seawater, SA ||||||||||||| ||||| |||||||||||||||||||||||||||||||

9 Rock Salt (Poland) |||||||||||| |||||||||| |||||||||||||||||||||||||||||||||||

10Himalayan Crystal Salt ( 250Ma Rock Salt, Pakistan). |||||||||||||| ||||||||| |||||||||||||||||||||||||||||||||||||

5 ISM Table Salt |||||||||||||||||||| |||||||| ||||||||||||||||||||||||||||||||||||||||||||||

7 Unbranded Table Salt |||||||||||||||||||||||| ||||||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| ||||||

4 Coles Iodised Salt (evap. seawater) |||||||||||||||||||||||||| |||||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| ||||||||||||

2 Saxa Cooking Salt (evap. seawater) ||||||||||||||||||||||||||||| ||||||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| |||||||||||||||

6Water Softener Salt (unknown comp.) * |||||||||||||||||||||||||||||| 65862 |||||||||| 1088 |||||||||||||||||||||||||||||||||||||||||||||||||||

|||||||||||||||||||||||||| 173578

The Photon-Counting Imaging System (PCIS)

-

Quantitative TL and OSL Imagery

Modified Minisys reader

High sensitivity LN/CCD detector

Broad spectrum high capture optics

Optical stimulation sources

Optical filtering capability

Integration electronics

Automation software systems

Photon-Counting Imaging System (PCIS)

Architecture

PCIS Luminescence Imaging CapabilityPCIS Luminescence Imaging Capability

The bright inclusions are mineral grains emitting TL (acquired by natural irradiation over the 50 years since firing)

Natural TL from 50 year Natural TL from 50 year old house brickold house brick

Aluminum Oxide ChipAluminum Oxide Chip Red TL integral measured from 130-260°C following 0.18 Gy dose (equates to 3 x 109 counts/Gy)

Quantitative Quantitative imaging of irradiated slices, including brick and concreteimaging of irradiated slices, including brick and concrete•• using a unique facility under development at the RSES, Australiausing a unique facility under development at the RSES, Australian National University n National University

Irradiation

Concrete slice (app. 5 mm square) after 20 Gy dose applied from direction as shown

Concrete slice (app. 8 mm length) after 9 Gy dose applied from Z (above) direction

TL from Australian Lake Salt crystals -

PCIS Image

PCIS Image; False Colour, Unprocessed Data.No filters; 200-1050nm spectral range

20Gy beta dose; then TL measured at 2K/s

The brightest grain shown here has emitted 5.7 x 107

counts

The total light sum of all grains is approximately 4.2 x 108 counts

Sensitivity is ~ 2 x 106

counts/Gy/mg for this salt sample

OSL: 470 nm Stimulation

UV emission: U 340 filter

1st sec Lightsum=1.8 x 105 cts/Gy

Total Lightsum~ 3 x 105 cts/Gy

TL 200ºC – 300ºC; 6 Gy beta dose;No filters (200 – 1050 nm)TL Lightsum = 1.6 x 108 counts. Corresponds to 2.5 x 107 cts/Gy

Sample #3

(“Woolworths Homebrand”)

5 mg aliquot

IRSL: 880 nm Stimulation

Red emission: 3 mm BG 39 filter

1st sec Lightsum=2.8 x 105 cts/Gy

Total lightsum~ 2 x 106 cts/Gy

Red/Near-IR TL (695-1050 nm)Sample #3 (“Woolworths Homebrand”); 6 Gy beta doseTL integrated from 200 – 300ºC; Schott RG 695 filter

TL Lightsum = 5.2 x 107 countsCorresponds to 1.7 x 106 cts/Gy/mg

Reheat image (note heater plate incandescence and grain images)

IPAS is a transdisciplinary institute incorporating physicists, chemists, biologists and environmental scientists; Director Professor Tanya Monro

New $80 million Integrated laboratories for research in Photonics and Sensing, University of Adelaide Nth. Tce campus

Builds on University of Adelaide expertise in soft glass optical fibre research and silica fibre fabrication

Aims to develop new technologies in areas including:

1. Fibre lasers (medicine & Defence)2.2. Luminescence for detection of trace materials and environmental Luminescence for detection of trace materials and environmental dosimetrydosimetry3. “Smart”

fibre sensors using surface chemistry techniques4. Detection of viruses and cancer biomarkers (functionalised fibre sensors)5. Evolutionary Biology & Photonics –

assess impact of climate change on biodiversity

IPAS Concept & Goals

Principal IPAS Activity Areas

DSTO / Univ. of Adelaide Centre of Expertise in Luminescence

(Part of IPAS)

Standing and Deployable Capability forStanding and Deployable Capability for

Detection of Prior Radiation ExposureDetection of Prior Radiation Exposure

Principal method: Luminescence (TL or OSL) analyses of materialsPrincipal method: Luminescence (TL or OSL) analyses of materials (including brick, tiles, porcelain, drywall, concrete and sedime(including brick, tiles, porcelain, drywall, concrete and sediment) to nt) to reveal radiation exposure in excess of natural backgroundreveal radiation exposure in excess of natural background

DSTO / Univ. of Adelaide Centre of Expertise in Luminescence

A Key Goal is the testing and extension of protocols on new A Key Goal is the testing and extension of protocols on new and established materials, to develop Standard Operating and established materials, to develop Standard Operating

Procedures enabling analysis rapidly and flexiblyProcedures enabling analysis rapidly and flexibly

Summary

New Material Example:

Salt has high sensitivity to beta radiation: TL, OSL & IRSL detection limits are < 1mGy using 10 mg portions of sample

Salt appears a suitable material for Retrospective Dosimetry

Australian Luminescence Analysis capacity is currently focussed on the specialist technique of Optical Dating using OSL from Quartz

An emergency response will also require utilising less-studied materials

Well-defined SOPs for these materials are essential

A key goal of the Centre of Expertise in Luminescence is the A key goal of the Centre of Expertise in Luminescence is the testing and extension of protocols on new and established testing and extension of protocols on new and established materials, to develop Standard Operating Procedures and materials, to develop Standard Operating Procedures and

enable rapid and flexible analysisenable rapid and flexible analysis