Phosphors and Scintillators Phosphors and Scintillators in Radiation Imaging Detectorsin Radiation Imaging Detectors……incorporated into real world ……incorporated into real world detectorsdetectors

Glenn C. TyrrellGlenn C. Tyrrell

Applied Scintillation Technologies LtdFluorescent & Scintillation Products for Industry, Science & Medicine

Outline and objectivesOutline and objectivesLuminescenceLuminescence–– IntroductionIntroduction

An overview of radiation imaging innovation at AST with An overview of radiation imaging innovation at AST with reference to synergy of materials science with physics.reference to synergy of materials science with physics.

XX--ray imaging and detectionray imaging and detection–– Commercial applicationsCommercial applications–– New imaging intensifying screensNew imaging intensifying screens–– New detectors (3DNew detectors (3D--RID)RID)

Neutron imaging and detectionNeutron imaging and detection–– Fast detectors at RALFast detectors at RAL–– ApplicationsApplications

UV and infrared imaging UV and infrared imaging –– Cost effective spectral enhancement of linear arrays and Cost effective spectral enhancement of linear arrays and

coated coated CCDsCCDs for instrumentationfor instrumentation

The single viewgraph The single viewgraph acknowledgement to the great acknowledgement to the great luminescence pioneersluminescence pioneersEarly historyEarly history–– 1010thth centurycentury Japan and ChinaJapan and China–– 1717thth centurycentury Sir Isaac Newton Sir Isaac Newton –– ThermoluminescenceThermoluminescence from from

diamonddiamond

–– 1717thth centurycentury VincentinusVincentinus CasciaroloCasciarolo (Bologna) coined the term (Bologna) coined the term phosphor phosphor PhosphorPhosphor –– ““gkgk. Light bearer”. Light bearer”–– ““BolognianBolognian Stone” Stone” (BaSO4)(BaSO4)

–– 1919thth centurycentury --EilhardtEilhardt WiedemannWiedemann (German Physicist) (German Physicist) –– coined word coined word luminescenceluminescence in 1888.in 1888.

Recent historyRecent history–– LenardLenard (1862(1862--1947) 1947) –– alkaline earth alkaline earth sulfidessulfides–– Pohl (1920s and 1930s) Pohl (1920s and 1930s) TlTl activated alkali halidesactivated alkali halides–– Humboldt Humboldt LeverenzLeverenz (1940s and 1950s) (1940s and 1950s) ZnSZnS–– GintherGinther (1960s) (1960s) –– neutron detection glassesneutron detection glasses

Major applications of phosphorsMajor applications of phosphors

DisplaysDisplays–– Cathode ray tube Cathode ray tube –– Plasma displays, Electroluminescence, Plasma displays, Electroluminescence, –– Oscilloscopes Oscilloscopes ––

LightingLighting–– Fluorescent lightingFluorescent lighting–– White White LEDsLEDs–– UV Therapy lamps UV Therapy lamps

Printing Printing –– Security inks, etc for banknotes and credit cardsSecurity inks, etc for banknotes and credit cards

Safety signs and stripsSafety signs and strips

XX--ray intensifying screensray intensifying screens

Novelty goods Novelty goods –– luminescent toysluminescent toys

….and how they can be applied to niche ….and how they can be applied to niche applications Iapplications I

Security

• Fast decay x-ray phosphors for x-ray backscatter detection

• High efficiency and low γsensitivity detectors for radiation threat monitors

• High efficiency screens for baggage scanning and postal imaging systems

• Image storage panels for rapid response terrorist threats

….and how they can be applied to niche ….and how they can be applied to niche applications IIapplications II

Medical

• High thickness phosphors for MeVradiotherapy systems

• Intensifying screens for medical imaging

• High efficiency screens for baggage scanning and postal imaging systems

• Image storage panels for rapid response terrorist threats

….and how they can be applied to niche ….and how they can be applied to niche applications IIIapplications III

Instrumentation

• Neutron scintillators for MWD oil well logging

• High resolution for state of the art TEM digital imaging systems

• CsI:Tl for dental x-ray applications and oxysulfide phosphors for panoramic imagers

• Alpha/beta detectors for health physics

•Y2SiO5:Ce, Gd2SiO5:Ce, YAP:Ce, YGG:Ce, YAG:Ce for mass spectrometry

•CdS:In, ZnO:Ga fast scintillators (2ns) for TOF mass spectrometry

XX--ray scintillatorsray scintillators

XX--ray Intensifying Screens ray Intensifying Screens –– A launch of a new series of A launch of a new series of oxysulfideoxysulfide screens with world class imaging performance.screens with world class imaging performance.

CsI:Tl on CsI:Tl on fiberfiber optics optics –– XioXio range incorporated into digital dental range incorporated into digital dental xx--ray systemsray systems

Fast decay phosphors for security Fast decay phosphors for security –– Pr dopedPr doped

High gain screens for High gain screens for MeVMeV imagingimaging

3D3D--RID RID –– melt detectors in silicon and glass devices. Depression melt detectors in silicon and glass devices. Depression of melt point to converge technologies.of melt point to converge technologies.

SS--typetype scintillatorsscintillators

Resolution (lp/mm) @ 10% contrast

2 4 6 8 10 12 14 16 18

Inte

nsity

(c

ompa

red

to L

anex

Fin

e (1

00%

))

0

100

200

300

400

500

600

700Lanex Fast Back

134 mg/cm2

Kasei DRZ

Lanex FF/Regular

Min-R 2190

Lanex Fine

1

2

3

4

5

1

2

3

4

51 GT10-85W2 GT4-70W3 GT4-60W4 GT10-86B5 MedeX Superfine Type I

BenefitsHigher resolution for same intensity OR increased light output for same resolution

Spatial frequency (lp/mm)

0 2 4 6 8 10 12

CTF

%

0

20

40

60

80

100

Schott 90:10 6µSchott 82:18 8µSchott 90:10 13µBPLSE6/85BPLI6/85Schott 75:25 6µ

Schott 90:10 (6)Incom BPLSE 6/85Schott 75:25 (6)Schott 82:18 (8)Incom BPLI 6/85(very poor low spatialFrequency)

CTF measurements of different fibre optic types with CsI coating

HIGH EMA

LOW EMA

High uniformity High uniformity CsICsI with excellent edge with excellent edge characteristicscharacteristics

HamamatsuHR

Applied Scintillation Xio F1

Significant inactive Edge area

-2%

+2%

0%

CsI:Tl Filled poresCsI:Tl Filled pores

20mm 500µm1.25 mm

Etched structures courtesy: Jan Linnros/Xavier Badel –KTH Stockholm

Neutron imaging and detectionNeutron imaging and detection

Commercial applicationsCommercial applications–– MWD Oil well loggingMWD Oil well logging–– Gemstone detection and imagingGemstone detection and imaging–– NDT (hydrogen inclusions in complex metal casts)NDT (hydrogen inclusions in complex metal casts)

Fundamental and applied physicsFundamental and applied physics–– Detectors for neutron Detectors for neutron spallationspallation sourcessources–– Neutron radiographyNeutron radiography–– Planetary studiesPlanetary studies

The process for neutron capture in a 6LiF/ZnS:Ag/polymer screen is by reaction of a thermal neutron with 6Li atom.

6Li + n 3H + 4He + 4.71 MeV

The probability of interaction of a thermal neutron with a screen is dependent upon the number of 6Li atoms in a fixed volume.

The neutron attenuation coefficients of any material can be determined using the following relation,

I =Io exp (-Nσt)where t is the thickness of the material

σ is the atomic cross section in barnsN is the number of 6Li atoms per cm3

Io is the incident neutron fluxI is the transmitted neutron flux

Neutron reaction in screen and glassNeutron reaction in screen and glass

thermal neutrons

ND screen

6 LiF particle

ZnS:Ag particle

Particle sizes exaggerated

n

Diagrammatic representations of Diagrammatic representations of physical processes occurring in a physical processes occurring in a LiLi66F/ZnS neutron detection screenF/ZnS neutron detection screen

miss

miss

hit

hit

c∆td

area σ=πd2collision tubeneutron

6LiF particlesZnS:Ag particles

αα

3H 3H

Benefits• High n/γ sensitivity 10-7 -10-8 in ISIS detectors at RAL: due to

improved phosphor purity.• 6Li reaction gives approx 68 times more energy per event than 157Gd

and couples efficiently into luminescent process.• Intrinsic efficiency of phosphor is high.

(Gd202S ~14%; ZnS:Ag ~23%)• λem at 460nm gives matched spectral output for standard bialkali and

many other PMTs• Excellent imaging performance – 6 lp/mm at 10% MTFDrawbacks• Reduced neutron absorption compared to Gd screens• Escape of light more difficult from thicker screens, may require

angular use to neutron increase path length.

Benefits of neutron screenBenefits of neutron screen

Neutron detectionNeutron detection

Applied Scintillation TechnologiesND scintillators (6LiF/ZnS) populate significant number of detector modules at the ISIS pulsed spallationsource at the Rutherford Appleton Laboratories,e.g. SANDALS:

GEM:HRPD:ENGIN-X:

2nd Target station detectors for 2008WISH?NIMROD?

GEM module from ISIS: courtesy N.J. Rhodes

CeCe-- doped Scintillation Glassdoped Scintillation Glass

extremely robust extremely robust

resistant to all organic and resistant to all organic and inorganic chemicals except inorganic chemicals except hydrofluoric acidhydrofluoric acid

can easily operate in can easily operate in temperatures ranging from temperatures ranging from --200200°°C to 250C to 250°°C. C.

allows them to be used in allows them to be used in conditions which prohibit conditions which prohibit the use of many other the use of many other scintillation materials.scintillation materials.

Fabrication of complex glass Fabrication of complex glass componentscomponents

Luminescent glass is difficult to manufacture in Luminescent glass is difficult to manufacture in complex shapescomplex shapesVariety of complex detector configurations can be Variety of complex detector configurations can be manufactured to a variety of finishesmanufactured to a variety of finishes

MEcury Space, Space ENvironment, GEochemistry and Ranging

JHU-APL NASA MESSENGER– Gamma Ray and Neutron Spectrometer (GRNS)

GRNS detector Ed Rhodes – JHU-APL

GS20 scintillators

+/- 5% pulse height matched

This instrument will detect gamma rays and neutrons that are emitted by radioactive elements on Mercury's surface or by surface elements that have been stimulated by cosmic rays. It will be used to map the relative abundances of different elements and will help to determine if there is ice at Mercury's poles, which are never exposed to direct sunlight.

Applications of lithium scintillator glass Applications of lithium scintillator glass ---- Positional sensitive detection Positional sensitive detection

Courtesy: Dr. Ralf Engels – KFA Julich

Neutron sensitive 3D scintillation structureNeutron sensitive 3D scintillation structure

66LiF/ZnS:Ag shows compact and complete filling within pore LiF/ZnS:Ag shows compact and complete filling within pore structures. structures. ParyleneParylene binds the phosphor to the pore and also adds a binds the phosphor to the pore and also adds a conformal cap layer to the pore.conformal cap layer to the pore.

Parylene

6LiF

ZnS:Ag

UV detectors and imagersUV detectors and imagers

Enhancement of spectral response of silicon linear Enhancement of spectral response of silicon linear diode arraysdiode arrays

UV passive converters for bioscience applications UV passive converters for bioscience applications ––Gel documentationGel documentation

Wavelength specific applications for specific dyes Wavelength specific applications for specific dyes for proteomic and genomics (e.g. Cy3, Cy5, for proteomic and genomics (e.g. Cy3, Cy5, AlexaAlexa, , etc)etc)

UV Enhancement of diode arraysUV Enhancement of diode arrays

Manufacturer DescriptionSony ILX 511

Sony ILX526A

Sony ILX 554B

Toshiba TCD1201D

modified silicon

150 200 250 300 350 400 450 500 550 600 650 700 750 800 λ (nm)

human eye sensitivitystandard silicon sensitivity

back-thinned device sensitivity

Sensitivity range of AST’s low cost spectrally extended silicon devices - ExtendUV

Germicidal UV

applications:curingbacterial controlEPROM erasingindustrial testing

Vacuum UV

applications:semi-conductormetals analysis

Black light

applications:non destructive test

Solar/sun-tan UV

applications:genetic finger printbio-sciencessun tan

V-UV UV-C UV-B UV-A Visible Near infra red

ArF KrF Nd:YAG (4th) XeCl HeCd N2 Nd:YAG(3rd)

193nm 248nm 266nm 305nm 325nm 337nm 355nm

UV

Lase

rs

185nm 254nm 302nm 312nm 365nmHg

Line

s

Extension of functionality of silicon devices using inorganic and organic phosphors

modified silicon

human eye sensitivitystandard silicon sensitivity

InGaAS device/streak camera sensitivity

Sensitivity range of AST’s low cost spectrally extended silicon devices -ExtendIR

400 500 600 700 800 900 1.0 1.1 1.2 1.3 1.4 1.5 1.6 λ (um)

UV Visible Near infra red

Typical Applications multi-photon microscopy security alignment machine vision telecoms research

LaserD

iodes

InxGa1-xP GaAsxP1-x AlxGa1-xAs GaAs InP GaSb/InxGa1-xAsP/InAsxP1-xInxGa1-xAs

0.76µm 0.65-0.9µm 0.65-0.9µm 0.9µm 0.91µm 1.3um - 1.55um - 1.67µm

Pr3+ based Er3+ based

1.31µm 1.55µm

Optical

Am

ps

Nd:YLF1st order Nd:YAG 1st

order1.053um 1.064um C

ryst

alLa

sersExamples of laser and

laser diode configurations which may be used with AST’s ExtendIR devices

Extension of functionality of silicon devices using inorganic and organic phosphors

Filtration of non-specific wavelengthsin Gd2O2S:Tb

Wavelength (nm)400 450 500 550 600 650 700 750

Inte

nsity

0

2

4

6

8

10

Col 1 vs GTLe116b Col 3 vs GT lee113 + 015 Col 5 vs GT + 113 +015 +

Emission spectrum of Visi-Dye Greenfollowing filtration

Wavelength (nm)400 450 500 550 600 650 700 750

Inte

nsity

Specific application of excitation of multiple dyed gels

SummarySummary

Phosphors and scintillators have a very Phosphors and scintillators have a very widespread practical applicationwidespread practical application

There are so many different flavoursThere are so many different flavours

AcknowledgementsAcknowledgements

Present AST development group membersPresent AST development group members–– Steve MoodySteve Moody–– Dr Jonathan Dr Jonathan CreaseyCreasey–– Luke WilliamsLuke Williams–– Dr Xiangdong Dr Xiangdong QuQu

Partners in 3DPartners in 3D--RID consortiumRID consortium–– University of Glasgow, STS, University of Glasgow, STS, MetorexMetorex, , MitthogskolenMitthogskolen, ,

KTH KTH StockolmStockolm, , CTU,UniversityCTU,University of of FreiburgFreiburg

Other collaboratorsOther collaborators–– University College London, Kings College London, RAL, University College London, Kings College London, RAL, –– All the unnamed key account partnersAll the unnamed key account partners

Applied Scintillation Technologies Ltd

Fluorescent & Scintillation Products for Industry, Science & Medicine

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