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Luminescence of common materials application to national security spooner






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    Luminescence of common materials application to national security spooner Luminescence of common materials application to national security spooner Presentation Transcript

    • 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 Sensing School 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 Exposure Does 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 Support for UN weapons inspection efforts. Detection of cleared ‘dirty bomb’ construction or storage sites. • forensic analysis of bunkers, buildings and laboratories cleaned and refurnished • forensic analysis even when free for non-nuclear cover activity. of isotopic contamination. Prevention Detection Recovery Response Retrospective population exposure assessment. • measure of extent of the affected area. • quantification of radiation exposure over the affected area
    • Luminescence Mechanism Conduction Band thermal or Ea optical release Trap     ra light di at emission io n Valence Band The population of trapped charge is proportional to the absorbed dose - enabling quantitative dosimetry
    • Principal Steps in Luminescence Analysis Sample cores are extracted from common building materials at suspect sites… Chemically prepared … Then measured in the Laboratory Photon-Counting Imaging System at ANU enables analysis of slices and potential rapid Environmental radioactivity measurements are also assessment of dose-depth profiling made to correct for the natural radiation background Including use of a NaI portable Gamma-ray Spectrometry, here undergoing calibration at Geosciences Australia, Canberra
    • Luminescence Technique Numerous reported applications in the open literature:  Retrospective nuclear accident dosimetry  Art authentication  Detection of illicit food irradiation  Atomic bomb radiation effects  Chronology of human evolution  Geomorphology & Soil Science  Megafaunal extinction/climate change BUT: requires very experienced personnel
    • Extension to “New” Signals and Materials 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-studied to 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
    • Key Goal – Standard Operating Procedures A Key Goal is the testing and extension of protocols on new and established materials, to develop Standard Operating Procedures to enable rapid and flexible analysis 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 Example – Analysis of Brick Schematic diagram illustrating current standardised sectioning used to sample brick for depth-dose measurements
    • Opportunistic Dosimetry Utilises materials that fortuitously occur in the incident environment, or are carried in by people Contrary 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 Dosimetric Materials at Habitations: Items carried by people, such as:  Ceramics • Glass (spectacles, watches etc)  Porcelain & tiles • Jewelry  Bricks • Credit cards  Pottery • Electronic components  Mortar & Concrete • Hard plastics (some?) • Some foodstuffs  Glass  Salt  Hard plastics (some?)  Gyprock  Mud-based insect nests  Carbonate materials (limestone, marble, calcite etc)  Quartz, Feldspar & Zircon grains
    • 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 Spectra 2. Kinetic Analysis 3. TL Sensitivity Changes During Heating 4. OSL & IRSL Dose Response 5. OSL & IRSL Pulse-Annealing Spectra 6. OSL & IRSL Sensitivity Summary 7. Imaged OSL, IRSL, TL
    • TL Emission Spectra All 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 Sample #3; “Woolworths Homebrand” Salt chosen due to representative glow curve shape and strong Red TL emission Heating rates 5 K/s – 0.002 K/s 240ºC peak (5K/sec) Glow5n E= 1.45 eV 100ºC peak (5K/sec) s= 7.9 x 1013 s-1 Glow2n Lifetime20ºC = 6.6 hours Lifetime20ºC = 3.9 ka Glow1bn 5 deg/s 200ºC peak (5K/sec) Glow05bn 0.01 2 deg/s Area Normalised TL Lifetime20ºC = 0.64 ka Glow02n 1 deg/s Glow01n 0.5 deg/s Glow005n 0.2 deg/s Glow002n 0.1 deg/s Data for 100ºC peak 3 510 0.05 deg/s 19 Glow001n 18 0.02 deg/s 17 Glow0002n 0.002 K/s 0.01 deg/s Ln(Tmax2/B) 16 15 0.02 K/s 0.002 deg/s 14 13 0.2 K/s 12 1.0 K/s 11 0 0.0027 0.0029 0.0031 0.0033 0 100 200 300 1/T T1 Temperature (ºC)
    • OSL (after PH 150ºC) IRSL (after PH 150ºC) OSL Sample Provenance (Cts/Gy/mg) (Cts/Gy/mg)*25 100 sec shine # (1s shine) (1s 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 |||||| |||||| |||||||||||||| Woolworth's HomeBrand Salt (evap. |||||| 11549 ||||||| 771 |||||||||||||| 29861 3 seawater) 19 Sydney, Canada (Huston Texas) ||||||| |||| |||||||||||||| 16 Table Salt, UK, Silver Sachet |||||||||||| 26758 ||||||| 1028 |||||||||||||||||| 39637 14 Evap. Seawater ||||||| ||||| |||||||||||||||||| Table Salt, UK Roadhouse, Blue ||||||||||| |||||||||| |||||||||||||||||| 15 Sachet JFK Airport, USA (Savannah |||||||||||| ||||| ||||||||||||||||||||||| 18 Georgia) 20 Halifax Canada ||||||||||||||||| ||||| ||||||||||||||||||||||||||||||| 8 Evap. Seawater, SA ||||||||||||| ||||| ||||||||||||||||||||||||||||||| 9 Rock Salt (Poland) |||||||||||| |||||||||| ||||||||||||||||||||||||||||||||||| Himalayan Crystal Salt ( 250Ma Rock |||||||||||||| ||||||||| ||||||||||||||||||||||||||||||||||||| 10 Salt, Pakistan). 5 ISM Table Salt |||||||||||||||||||| |||||||| |||||||||||||||||||||||||||||||||||||||||||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| 7 Unbranded Table Salt |||||||||||||||||||||||| ||||||||| |||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| 4 Coles Iodised Salt (evap. seawater) |||||||||||||||||||||||||| |||||||| |||||||||||| ||||||||||||||||||||||||||||||||||||||||||||||||||| 2 Saxa Cooking Salt (evap. seawater) ||||||||||||||||||||||||||||| ||||||||| ||||||||||||||| Water Softener Salt (unknown comp.) ||||||||||||||||||||||||||||||||||||||||||||||||||| |||||||||||||||||||||||||||||| 65862 |||||||||| 1088 6 * |||||||||||||||||||||||||| 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 Capability Quantitative imaging of irradiated slices, including brick and concrete • using a unique facility under development at the RSES, Australian National University Concrete slice (app. 8 mm length) after 9 Gy dose applied from Z (above) direction Concrete slice (app. 5 mm square) after 20 Gy dose applied from direction as shown Irradiation Aluminum Oxide Chip Red TL integral measured from 130-260°C following 0.18 Gy dose (equates to 3 x 109 counts/Gy) Natural TL from 50 year old house brick The bright inclusions are mineral grains emitting TL (acquired by natural irradiation over the 50 years since firing)
    • 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 Sample #3 Stimulation (“Woolworths Homebrand”) UV emission: U 340 filter 5 mg aliquot 1st sec Lightsum =1.8 x 105 cts/Gy TL 200ºC – 300ºC; 6 Gy beta dose; No filters (200 – 1050 nm) Total Lightsum TL Lightsum = 1.6 x 108 counts. ~ 3 x 105 cts/Gy Corresponds to 2.5 x 107 cts/Gy 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 dose TL integrated from 200 – 300ºC; Schott RG 695 filter TL Lightsum = 5.2 x 107 counts Reheat image (note heater plate Corresponds to 1.7 x 106 cts/Gy/mg incandescence and grain images)
    • IPAS Concept & Goals 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. Luminescence for detection of trace materials and environmental dosimetry 3. “Smart” fibre sensors using surface chemistry techniques 4. Detection of viruses and cancer biomarkers (functionalised fibre sensors) 5. Evolutionary Biology & Photonics – assess impact of climate change on biodiversity
    • Principal IPAS Activity Areas
    • DSTO / Univ. of Adelaide Centre of Expertise in Luminescence (Part of IPAS)
    • DSTO / Univ. of Adelaide Centre of Expertise in Luminescence Standing and Deployable Capability for Detection of Prior Radiation Exposure Principal method: Luminescence (TL or OSL) analyses of materials (including brick, tiles, porcelain, drywall, concrete and sediment) to reveal radiation exposure in excess of natural background A Key Goal is the testing and extension of protocols on new and established materials, to develop Standard Operating Procedures enabling analysis rapidly and flexibly
    • Summary  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 testing and extension of protocols on new and established materials, to develop Standard Operating Procedures and enable rapid and flexible analysis 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