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 Outline and objectivesobjectives

LuminescenceLuminescence– IntroductionIntroduction

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

X-ray imaging and detectionX-ray imaging and detection– Commercial applicationsCommercial applications– New imaging intensifying screensNew imaging intensifying screens– New detectors (3D-RID)New detectors (3D-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 Cost effective spectral enhancement of linear arrays

and coated CCDs for instrumentationand coated CCDs for instrumentation

The single viewgraph The single viewgraph acknowledgement to the great acknowledgement to the great luminescence pioneersluminescence pioneers

Early historyEarly history– 1010thth century century Japan and China Japan and China– 1717thth century century Sir Isaac Newton – Sir Isaac Newton – Thermoluminescence from Thermoluminescence from

diamonddiamond

– 1717thth century century Vincentinus Casciarolo (Bologna) coined the term Vincentinus Casciarolo (Bologna) coined the term phosphor Phosphor – “gk. Light bearer”– “Bolognian Stone” phosphor Phosphor – “gk. Light bearer”– “Bolognian Stone” (BaSO4)(BaSO4)

– 1919thth century century - -Eilhardt Wiedemann (German Physicist) – coined word Eilhardt Wiedemann (German Physicist) – coined word luminescenceluminescence in 1888. in 1888.

Recent historyRecent history– Lenard (1862-1947) – alkaline earth sulfidesLenard (1862-1947) – alkaline earth sulfides– Pohl (1920s and 1930s) Tl activated alkali halidesPohl (1920s and 1930s) Tl activated alkali halides– Humboldt Leverenz (1940s and 1950s) ZnSHumboldt Leverenz (1940s and 1950s) ZnS– Ginther (1960s) – neutron detection glassesGinther (1960s) – neutron 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 LEDsWhite LEDs– 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

X-ray intensifying screensX-ray intensifying screens

Novelty goods – luminescent toysNovelty goods – luminescent toys

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

Security

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

• High efficiency and low sensitivity 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 .and how they can be applied to niche applications IIniche applications II

Medical

• High thickness phosphors for MeV radiotherapy 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 .and how they can be applied to niche applications IIIniche applications 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

X-ray scintillatorsX-ray scintillators

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

CsI:Tl on fiber optics – Xio range incorporated into CsI:Tl on fiber optics – Xio range incorporated into digital dental x-ray systemsdigital dental x-ray systems

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

High gain screens for MeV imagingHigh gain screens for MeV imaging

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

S-typeS-type scintillators scintillators

Resolution (lp/mm) @ 10% contrast

2 4 6 8 10 12 14 16 18

Inte

ns

ity

(c

om

pa

red

to

La

ne

x F

ine

(1

00

%))

0

100

200

300

400

500

600

700

Lanex Fast Back134 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

CT

F %

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 CsI with excellent edge High uniformity CsI with excellent edge characteristicscharacteristics

Hamamatsu HR

Applied Scintillation Xio F1

Significant inactive Edge area

-2%

+2%

0%

CsI:Tl Filled poresCsI:Tl Filled pores

20mm 500m1.25 mm

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

Neutron imaging and Neutron imaging and detectiondetection

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

casts)casts) Fundamental and applied physicsFundamental and applied physics

– Detectors for neutron spallation sourcesDetectors for neutron spallation sources– 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 (-Nt)where t is the thickness of the material

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 Neutron reaction in screen and glassglass

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 F/ZnS neutron detection screenscreen

miss

miss

hit

hit

ct

d

area d2collision tube

neutron

6LiF particles

ZnS:Ag particles

3H

3H

Benefits

• High n/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%)

• em 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 spallation source at the Rutherford Appleton Laboratories,e.g. SANDALS:

GEM:HRPD:ENGIN-X:

2nd Target station detectors for 2008

WISH?NIMROD?

GEM module from ISIS: courtesy N.J. Rhodes

Ce- doped Scintillation GlassCe- doped 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 -200°C to 250°C. 200°C to 250°C.

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

Variety of complex detector configurations can Variety of complex detector configurations can be manufactured to a variety of finishesbe manufactured 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 LiF/ZnS:Ag shows compact and complete filling within pore structures. pore structures.

Parylene binds the phosphor to the pore and also adds Parylene binds the phosphor to the pore and also adds a conformal cap layer to the pore.a conformal cap layer to the pore.

Parylene

6LiF

ZnS:Ag

UV detectors and UV detectors and imagersimagers

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

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

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

UV Enhancement of diode UV Enhancement of diode arraysarrays

Manufacturer Description

Sony 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 (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

Laser

s

185nm 254nm 302nm 312nm 365nm

Hg

Lin

es

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 (um)

UV Visible Near infra red

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

Laser

Dio

des

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

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

Pr3+ based Er3+ based

1.31m 1.55m

Op

tica

lA

mp

s

Nd:YLF 1st order

Nd:YAG 1st order

1.053um 1.064um

Cry

sta

lLasersExamples 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

nsi

ty

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

nsi

ty

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 CreaseyDr Jonathan Creasey– Luke WilliamsLuke Williams– Dr Xiangdong QuDr Xiangdong Qu

Partners in 3D-RID consortiumPartners in 3D-RID consortium– University of Glasgow, STS, Metorex, Mitthogskolen, University of Glasgow, STS, Metorex, Mitthogskolen,

KTH Stockolm, CTU,University of FreiburgKTH Stockolm, CTU,University of Freiburg Other collaboratorsOther collaborators

– University College London, Kings College London, University College London, Kings College London, RAL, 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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