ScienceImagersasHigh-EnergyRadia4onSensors
AshleyCarltonMassachuse<sIns4tuteofTechnology
SpaceTelecommunica4ons,Astronomy,andRadia4onLaboratory
ThesisProposalDefenseMay23,2017
33-218
Outline• Introduc)on
– BackgroundandMo)va)on– ThesisOverview
• LiteratureReview– ImagersasRadia)onSensors
• Approach&Methodology– GalileoSSIandEPD– DataAnalysisofSSIObserva)ons– Simula)onsusingGeant4– Ini)alresultsandcomparisontotheEPD
• NextSteps– GalileoNIMS– In-labtes)ng
• ThesisContribu)ons• Schedule
– Research,academic,degree
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JovianMagnetosphere
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Imagesource:PearsonEduca1on,2011
Earth JupiterEquatorialradius
[km] 6.38x103 7.15x104
Magne)cmoment[G-cm3] 8.10x1025 1.59x1030
Dipole)lt[o] 11.5 11
Rota)onperiod[hr] 24.0 9.925
Aphelion/perihelion[AU] 1.01/0.98 5.45/4.95
ContoursoftheintegralelectronandprotonfluxesattheEarthandJupiter.ImagecourtesyofI.Jun.
Jovianenvironmentisdominatedbyelectrons. [1,2]
LimitedHigh-EnergyMeasurements
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TrajectoriesofspacecraDthathavemadehigh-energypar1clemeasurementswithrespecttoJupiter.RJ=71,492km.Imagesource:M.deSoria-SantacruzPichetal.,2016.
SpacecraO Orbit Date
Pioneer10 flyby December1973
Pioneer11 flyby December1974
Voyager1 flyby March1979
Voyager2 flyby July1979
Galileo 35orbits Dec.1995–Sept.2003
RJ=71,492km
MissionstoJupiterCurrentandplannedmissionstoJupiterdonothaveinstrumentsdedicatedtomeasuring>1MeVelectrons.
• Juno:– InorbitatJupiter(JOI:July2016)– Highlyellip)calorbitoverthepoles[4]
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• EuropaClipperconcept:– InphaseBofdesign,launchdate
~2024– Consistsofanorbiter(flyingby
Europaoneachof~40-45highlyellip)calorbits)andlander[5,6]
VideoshowingtheplannedJunoorbitwithrespecttoJupiterandtheGalileanmoons.Videocreatedusing
NASA’sEyes:hXps://eyes.nasa.gov/
Whydowecareabout>1MeVe-?• ScienceMo)va)on:
– Magnetosphericscience– MeVelectronsaffectsurfacesofJovianmoons[7,8]
• EngineeringMo)va)on:– Missionopera)ons– Anomalyinves)ga)onandmi)ga)on[9,10]
– Improvementofmodelsforfuturemissiondesign
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Effect EnvironmentSource
1.Radia)ondose/doserate
100keV–50MeVelectrons1MeV–100MeVprotons
2.SurfaceCharging/ESD
1keV–1MeVelectrons
3.SingleEventEffects 1–100MeVprotons>1MeV/Nuc.heavyions
4.InternalCharging/IESD
1– 10+MeVelectrons
LimitedHigh-EnergyMeasurements
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Flybysonly
~Equatorialorbit
Flybysonly
Polarorbit,minimalcoverageofradia)ondoseenergies
Nohigh-energypar)clemeasurementsplanned
Summaryofenerge1celectronmeasurementsatJupiter.Thecoloredregionshighlight
environmentswithpar1cularradia1onrisks.Imagecredit:A.Carlton
ThesisResearchStatement
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Developamethodtoextractquan4ta4veinforma4onaboutthehigh-energy(>1MeV)electronenvironmentatJupiterusingexis4ngtechnologieson-board.
ScienceimagersassensorsoftheMeVelectrons.
DevelopthetechniqueusingimagersontheGalileospacecrahandcompareresultstoGalileoEnerge)cPar)cleDetector.
ImagersasRadia4onSensors
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Averageenergyneededfore-hpairgenera)oninSilicon:3.6eV
Q∝ΔE
• Impactioniza)on
• Energe)cchargedpar)cleslosekine)cenergypredominatelythroughinelas)ccollisionswiththeorbitalsiliconelectrons
• Electronspromotedfromvalencetoconduc)onband
Conduc)onband
Valenceband¢h
�e-
Si
Si
Si
Si
Si .... ....
Si
Si
Si
Si
Si .... ....
....
Valenceelectron
Covalentbond
Egap1.12eV
[11,12]
LiteratureReview
• Radia)on“hits”/noiseextractedfromimagers– Radia)onhitremovalalgorithms
[12,13,14,15]– Comparingradia)onhitrateto
simula)ons[16]– Comparingradia)onhitrateto
pre-flighttes)ngandtodifferentloca)onsonorbit[17,18,19]
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OriginalCCDimage.Right:Imagewithcrossesindica1nganoisepixel.Imagesource:GirónandCorrea,2010.
Radia1on-inducedsignalratesinSSIimagesasafunc1onofRJ.Imagesource:Klaasenetal.,1999.
• Imagersasradia)ondetectors– Diagnos)csofiner)alconfinement
fusionimplosions[20,21]– Threshold-crossingrates[22,23]
ApproachandMethodology(1/2)• TheGalileospacecrahorbitedJupiterfromDecember1995toSeptember
2003,comple)ng35orbits.
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Imagesource:NASAhXps://solarsystem.nasa.gov/images/galleries/Galileo_Diagram_No_Labels.jpg
• DevelopthetechniqueusingSSIandNIMSimagersonGalileoascasestudiesandtheEPDtovalidate.
Beltonetal.,1992
Solid-StateImager(SSI)
Near-InfraredMappingSpectrometer(NIMS)
Carlsonetal.,1992
[24,25,26]
ApproachandMethodology(2/2)ForGalileoSSIandNIMS,wewill:• Determinetheenergy(orenergies)the
imagerissensi)veto• Calculatethefluxatagivenenergy• CompareresultstotheGalileoEPD
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Imagesource:NASAhXps://solarsystem.nasa.gov/images/galleries/Galileo_Diagram_No_Labels.jpgBeltonetal.,1992
Solid-StateImager(SSI)
Near-InfraredMappingSpectrometer(NIMS)
Carlsonetal.,1992
Energe4cPar4cleDetector(EPD)
Williamsetal.,1992[24,25,26]
Approach
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• Collectrawinstrumentframeswithradia)onnoise
• Processframestoremovetargetanddarkcurrent
• Usecalibratedinstrumentgaintodetermineenergydeposited
DataAnalysis:Radia4onNoiseinSSIImages
• ModelinstrumentinGeant4
• Performmono-energe)csimula)ons
Simula4ons:InstrumentResponsetoMeVe-
• Determineinstrumentresponsetomono-energe)cbeams
• Determinefluxatagivenenergy
ExtractEnvironmentInforma4on
ComparetoEPDforvalida4on.
Approach:DataAnalysis(1/2)
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1.Collectrawinstrumentframes(pictures)withradia)onnoise.
ScreenshotoftheimageatlasfromthePlanetaryDataSystem(PDS),whichcanbeaccessedhere:hXps://pds-imaging.jpl.nasa.gov/
ExampleSSIObserva)on:• Orbit33,18Jan2002• Integra)onTime:195.83ms
(exposure)+8.667s(read-out)• ImagetakenatRJ=17.1
GalileoSSIimageofEuropa,downloadedfromthePDS.
2.Processframestoremovetargetobjectanddarkcurrent,leavingonlyradia)onhits.
Moonremoved
Right:Contrastedimagewiththeintensityscalerepresen1ngthedigitalnumberofthepixel.
Approach:DataAnalysis(2/2)
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3.Usecalibratedinstrumentgaintodetermineenergydepositedperpixelperframefromnoise.Makehistogramofdepositedenergy.
Gainstatesforconver1ngtodigitalnumbertoelectrons[19].
CommandedGain
GainStateRa4oFactors
Conversion[e-/DN] Notes
0=Gain1 1.00 1822Summa)on
modeonly,~400Kfullscale
1=Gain2 4.824 377.4 Lowgain,~100Kfullscale
2=Gain3 9.771 186.5 ~40Kfullscale
3=Gain4 47.135 38.66 Highgain,~10Kfull255DNscale
Histogramoftheenergydepositedbypixel,aDerthedarkcurrentandmoonhavebeenremoved.
1bin=1DN=377.4e-=1.36keV
Approach:Simula4ons(1/2)
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1.Modelfullinstrument(includingshielding)inachargedpar)cletransportsimula)oncode,Geant4.
Redorange:tantalumBrown:printedwiringboard
Yellow:siliconDarkblue:aluminum
Cyan:1taniumGreen:invarPink:silica
Imagesource:A.Carlton
Approach:Simula4ons(2/2)
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2.Performsimula)onsofSSIundermono-energe)cenvironments.
Resul1ngimagefromsimula1ng1billion100MeVelectronsontheSSI.Imagesarein800by800pixelswiththeintensityscalerepresen1ngenergydepositedinapixel.
Sourceenvironment Sphereradia)nginwards
Radiusofsourcesphere 150cm
Numberofsourcepar4cles 1E9electrons
Energiessimulated 1,3,5,10,30,50,100,and200MeV
Simula1onparametersused.Theinputisessen1allyafluence,sincethe1mecomponentisnegligiblysmallforthesehigh-energyelectrons.
Histogramofresultsfromsimula1onof10billion50MeVe-.
Mono-energe4cSims:EnergyDeposited
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Mono-energe4cSims:EnergyDeposited
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Shapesofthecurvesaresimilaràmaynotbepossibletoextractspectra
Mono-energe4cSims:EnergyDeposited
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Integralenergychannel~>10MeV
Geant4Results• Sourceenvironmentsimulated:– Onebillionmono-energe)celectrons– Sphereradia)nginwardwithacosinedistribu)onandradiusr=150cm
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Ra4oofthenumberofpar4clesreachingthe
detectorandthenumberofpixelswithhits,G1
Numberofpar4clesthatreachthedetector
Numberofpixelswithenergydeposited
Geant4Results• Sourceenvironmentsimulated:– Onebillionmono-energe)celectrons– Sphereradia)nginwardwithacosinedistribu)onandradiusr=150cm
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Ra4oofthenumberofpar4clesreachingthe
detectorandthenumberofpixelswithhits,G1
Numberofpar4clesthatreachthedetector
Numberofpixelswithenergydeposited
WefindG1=0.53±0.014(95%conf.)par)cles/pixel
GeometricScalingFactors
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R1 = f0G2
1. Calculatethera)oofpixelswithhitstopar)clesthatdepositenergyonthedetector• R0:pixelhits/totalpixels• R1:par)cles/totalpixels
2. Tofindthenumberofpar)clesperunitarea,dividebythepixelsize
• Pixelsize:15μmx15μm
3. Usingtheknownfluencefromthesimula)onf0,computethegeometricviewfactor,G2
DeterminingthefluxfrompixelswithhitsontheSSIobserva)onrequiresscalingfactorsthatcanbecalculatedwiththeGeant4simula)ons.
R1 = R0G1 G1=0.53par)cles/pixel
f0 =N
4π (4πr2 )Simula)onfluence:f0=1.258x103#/cm2-sr
[par)cles/cm2]
Example:SSIObserva4on5101r,Orbit22- SSIimageofAmalthea,takenat9.4RJ- 295pixelswithhitsoutof4161pixels(7.09%)- Integra)on)me:62.5ms,Readout)me:8.667s- Pixelsize:15μmx15μm
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1. Calculatethepixelhitrate:
2. Par)clerate(frompar)clesintheenvironmentfromallenergies):
3. ApplythescalefactorG2for10MeVandcalculatetheflux:
Image5101r,fromNASAPDS.
ComparisontoGalileoEPD
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Log-normalfinngandEPD
uncertain1escanbefoundinJunet
al.,2005.
NextSteps• GalileoSSI– Buildconfidencein~10MeVintegralchannelbyperformingmoreGeant4simula)ons
– ProcessallremainingSSIimagesandextractenergydeposi)oncurvesand>10MeVflux
– ComparecurvestoEPD
• GalileoNIMSanalysistodemonstratetechniquecanbeappliedtootherimagers
• Tes)ngwithelectronbeamforvalida)onofGeant4modelingphysics– Testsolid-statedetectorresponsetoenerge)celectronbeamsunderdifferentamountsofshielding
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ExpectedContribu4ons• Inventatechniqueanddesignageneralizedproceduretoextract
high-energy(>1MeV)electronenvironmentinforma)onfromsolid-statedetectors.– Demonstratehowtofindatleastoneintegralenergychannelfromthe
GalileoSolid-StateImaginginstrument.– Demonstratehowtofindatleastoneintegralenergychannelfromthe
GalileoNear-InfraredMappingSpectrometer(NIMS).– DemonstrateagreementwiththeGalileoEnerge)cPar)cleDetector
(EPD).– AnalyzeresultscomparedtocurrentJovianradia)onmodels(GIRE-2,
suppliedbyJPL).
• Testsolid-statedetectorinelectronbeamstovalidateGeant4modelingphysics.
• Composerecommenda)onsandrequirementsfortes)ng,calibra)on,
andopera)onalproceduresforaninstrumentontheEuropaClippermissioninordertousethetechniquedevelopedinthisthesis.
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ResearchSchedule
Summer2017 Fall2017 Spring2018 Summer2018 Fall2018
GalileoSSI:Completeaddi)onalmono-energe)csimula)onsoftheSSIinGeant4todefineconfidenceintervalonenergyandfluxscalingfactors.Tes4ng:Supporttestplanandpartprocurement;Modeltestset-up;PerformtestsinlabWri4ng:Submitpaperonmastersresearch
GalileoSSI:Completeextrac)onofradia)oninfoandprocessingofallSSIimages;ComparisontoEPDandGIRE-2.GalileoNIMS:Beginanalysisofdata;Determinehowtoextracttheenergyandhitrateinfofromtheimages.Tes4ng:Post-processresults
GalileoNIMS:ModelingofNIMSinGeant4;Performsimula)onsWri4ng:WriteandsubmitpaperonSSIworkConferencepresenta)on(TBD)
GalileoNIMS:NIMSscalingfactors;ComparisonofNIMSresultstoEPDandGIRE-2,andtoSSI.Assessmentofgeneralizability,recommenda)onsforEuropaClipperinstrumentWri4ng:Writethesis
Wri4ng:Writethesis,defend,andgraduateConferencepresenta)on(TBD)
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AcademicRequirements
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Req. CourseNumber CourseTitle Semester
TakenGrade/Status
Major 16.413 Intro.toAutonomy&Decision-Making Fall2013 A
Major 16.851 SatelliteEngineering Fall2014 A
Major 16.363 Communica)onSystems Spring2015 A
Major 16.89 SpaceSystemsEngineering Spring2015 A
Major 16.899 SystemsEngineeringofFLAREproject Fall2016 A
Major 22.16 NuclearTechnologyandSociety Spring2015 A
Minor 16.910 Intro.toNumericalSimula)on Fall2014 A
Minor 16.343 SensorsandInstrumenta)on Spring2017 Inprogress
Minor 8.613OR8.701
PlasmaPhysicsORNuclearandPar)clePhysics Fall2017 Planned
DegreeMilestones
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DegreeRequirement DateComplete
QualifyingExams January2016MastersDegree May2016
ThesisProposalDefense May23,2017ThesisDefense Summer2018(TBR)
References(1/2)
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[1]F.Bagenal,T.Dowling,andW.McKinnon,eds.Jupiter:ThePlanet,SatellitesandMagnetosphere.CambridgeUniversityPress,2004.[2]H.Garrevetal.“TheJovianChargingEnvironmentandItsEffects–AReview”.In:IEEETransac1onsonPlasmaScience40.2(Feb.2012),pp.144–154.[3]M.deSoria-SantacruzPich,etal.,“Anempiricalmodelofthehigh-energyelectronenvironmentatJupiter”.InJ.Geophys.Res.SpacePhysics,121.10(2016).Pp.9732-9743.[4]S.Boltonetal.,“TheJunoMission”,In:ProceedingsoftheInt’lAstron.Union.6.S269(2010).Pp.92-100.[5]B.Goldsteinetal.,“EuropaClipperUpdate”.Presenta)onattheEuropaClipperOPAG,unpublished.Jan.2014.[6]C.PhillipsandR.Pappalardo.“EuropaClipperMissionConcept:ExploringJupiter’sOceanMoon”.In:EOS,Trans.Am.Geophys.Union95.20(2014),pp.165-167).[7]C.ChybaandC.Phillips,“Surface-SubsurfaceExchangeandtheProspectsforLifeonEuropa,”In:Proc.ofLunarandPlanetarySci.Conf,Vol.32,2001.[8]C.Paranicasetal.,“Europa’sRadia)onEnvironmentandItsEffectsontheSurface,”In:Europa.SpaceScienceSeries.UniversityofArizonaPress,2009.Chap.21,pp.529–544.[9]D.Has)ngsandH.Garrev,SpacecraD-EnvironmentInterac1ons.CambridgeAtmosphericandSpaceScienceSeries.Cambridge,UK:CambridgeUniversityPress,1996.[10]GordonWrenn.“ConclusiveEvidenceforInternalDielectricChargingAnomaliesonGeosynchronousCommunica)onsSpacecrah”.In:JournalofSpacecraDandRockets32.3(May1995).pp.514–520.[11]J.Janesick.Scien1ficCharge-CoupledDevices.Vol.PM83.Bellingham,Washington:SPIEPress,Jan.2001.[12]A.Yamashitaetal.“Radia)ondamagetochargecoupleddevicesinthespaceenvironment”.In:IEEETrans.onNuclSci44.3(June1997),pp.847–853.[13]A.Smithetal.“Radia)oneventsinastronomicalCCDimages”.In:Proc.SPIE4669,SensorsandCameraSystemsforScien)fic,Industrial,andDigitalPhotographyApplica)onsIII,172(April26,2002),pp.172–183.[14]L.ArchambaultL,T.Briere,S.Beddar,“Transientnoisecharacteriza)onandfiltra)oninCCDcamerasexposedtostrayradia)onfromamedicallinearaccelerator”.MedicalPhysics.2008;35(10):4342-4351.
References(2/2)
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[15]A.D.RestrepoGirónandH.LoaizaCorrea,“Anewalgorithmfordetec)ngandcorrec)ngbadpixelsininfraredimages.IngenieríaeInves1gación,30(2),(2010).pp.197-207.[16]R.CarlsonandK.Hand.“Radia)onNoiseEffectsatJupiter’sMoonEuropa:In-SituandLaboratoryMeasurementsandRadia)onTransportCalcula)ons”.In:IEEETransac1onsonNuclearScience62.5(Oct.2015),pp.2273–2282.[17]K.Klaasenetal.,“Opera)onsandcalibra)onofthesolid-stateimagingsystemduringtheGalileoextendedmissionatJupiter,”In:SPIEOpt.Eng.42(2)(Feb.2003).Pp.494-509.[18]K.Klaasenetal.,‘‘Calibra)onandperformanceoftheGalileosolid-stateimagingsysteminJupiterorbit,’’In:SPIEOpt.Eng.38(7),(1999),pp.1178-1199.[19]K.Klaasenetal.,‘‘Inflightperformancecharacteris)cs,calibra)on,andu)liza)onoftheGalileosolid-stateimagingcamera,’’In:SPIEOpt.Eng.,36(11),(1997),pp.3001-3027.[20]B.E.Burkeetal.“Useofcharge-coupleddeviceimagersforcharged-par)clespectroscopy”.In:ReviewofScien1ficInstruments68.1(1997),pp.599–602.[21]C.K.Lietal.“Charged-coupleddevicesforcharged-par)clespectroscopyonOMEGAandNOVA”.In:ReviewofScien1ficInstruments68.1(1997),pp.593–595.[22]C.E.Grantetal.“UsingACISontheChandraX-rayObservatoryasapar)cleradia)onmonitor”.In:SpaceTelescopesandInstrumenta1on2010:UltraviolettoGammaRay.EditedbyArnaud7732(2010),p.80.[23]C.E.Grantetal.“UsingACISontheChandraX-rayObservatoryasapar)cleradia)onmonitorII”.In:SpaceTelescopesandInstrumenta1on2012:UltraviolettoGammaRay,8443(Sept.2012).[24]M.Beltonetal.“TheGalileoSolid-StateImagingexperiment”.In:SpaceScienceReviews60.1(1992),pp.413–455.[25]R.Carlsonetal.“Near-InfraredMappingSpectrometerexperimentonGalileo”.In:SpaceScienceReviews60.1(1992),pp.457–502.[26]D.Williamsetal.“TheGalileoEnerge)cPar)clesDetector”.In:SpaceScienceReviews60.1(1992),pp.385–412.[27]S.Agos)nellietal.“Geant4—asimula)ontoolkit”.In:NuclearInstrumentsandMethodsinPhysicsResearchSec1onA:Accelerators,Spectrometers,DetectorsandAssociatedEquipment506.3(2003),pp.250–303.[28]I.Junetal.,“Sta)s)csofthevaria)onsofthehigh-energyelectronpopula)onbetween7and28jovianradiiasmeasuredbytheGalileospacecrah”,Icarus,178(2),15November2005,pp.386-394.
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HardElectronSpectrumatJupiter• ComparisonbetweenJovianandTerrestrialradia)onspectra
23May2017 A.Carlton 34
MissionstotheOuterSolarSystemSpacecraO Jupiter Cost Mass(wet)
Pioneer10 Jupiter:1973,flyby $350M(FY2001) 258kg
Pioneer11 Jupiter:1974,flyby;Saturn:1979,flyby 259kg
Voyager1 Jupiter:1979,flyby;Saturn:1980,flyby
$900M
2080kg
Voyager2 Jupiter:1979,flyby;Saturn:1981,flyby;Uranus:1986,flyby;Neptune:1989,flyby 2080kg
Galileo Jupiter:1995-2003,orbiter;1995,2003atmospheric $1.41B 2223kg
Ulysses Jupiter:1992,2004,gravityassist $318M(FY1989) 371kg
Cassini-Huygens
Jupiter:2000,gravityassist;Saturn:2004-present,orbiter;2005,Titanlander $3.27B 5712kg
NewHorizons Jupiter:2007,gravityassist;Pluto:2015,flyby $700M 478kg
Juno Jupiter:2016-present,orbiter $1.1B 3625kg
23May2017 A.Carlton 35
CurrentModelsandLimita4onsModelName Reference Descrip4onandComments
DivineandGarrev(D&G)
DivineandGarrev,1983
Firstcomprehensivemodeloftheradia)onandplasmaenvironmentaroundJupiterEmpirical,fromGeigertubetelescope(GTT)onPioneer10and11,andfromthecosmicraytelescopeonVoyager1and2.
DivineandGarrev(D&G),updated
Garrevetal.,2005 IncludeddatafromEarth-basedobserva)onsoftheJupitersynchrotronemissions
JovianSpecificEnvironment(JOSE)
ONERA,FranceSicard-Pietetal.,2011
BasedonSalammbôtheore)calcodeincombina)onwithdatafromtheEnerge)cPar)cleDetector(EPD)ontheGalileospacecrah
GalileoInterimRadia)onEnvironment(GIRE)andGIRE2
Garrevetal.,2002;Garrevetal.,2012;deSoria-Santacruzetal.,2016
Empiricalmodel,uses10-minaveragesfromtheEnerge)cPar)cleDetector(EPD)onGalileoV2addressesdiscon)nui)esattheboundarybetweenGIREandtheD&Gmodelsandextendsfrom~16RJtoupto~50RJ
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Currentmodelsarelimitedbylackofdata,bothspa)allyandtemporally.
KeyEnvironmentalInterac4ons
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Tablecredit:H.GarreX
High-EnergyPar4cleMeasurements• Juno:high-energypar)cle
measurementinstruments– JovianAuroralDistribu)on
Experiment(JADE):• Electrons:100eV–100keV• Ions(1-50amu):10eV–40keV
– JupiterEnerge)c-par)cleDetectorInstrument(JEDI):• Electrons:20keV–1MeV• Protons:15keVto3MeV
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Effect EnvironmentSource
1.Radia)ondose/doserate
100keV–50MeVelectrons1MeV–100MeVprotons
2.SurfaceCharging/ESD 1keV–1MeVelectrons
2.SingleEventEffects 1–100MeVprotons>1MeV/Nuc.heavyions
3.InternalCharging/IESD 1–10MeVelectrons
• EuropaClipper:noinstrumentscurrentlydedicatedtoMeVpar)cledetec)on
• Whydowecare?Whyisthisnot
enough?
Imagesource:NASA/JPL-Caltech
ExtractInforma4onfromExis4ngHardware• Scienceimagersare
1. Commontoexplora)onmissions,suchasthosetoJupiter
2. AffectedbyMeVpar)cles• ThreeinstrumentsonJuno
areCCDs• EuropaClipper:UVS,MISE,
EIS,andMASPEXaresensi)vetoMeVelectrons
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Imagesource:NASA/JPL-CaltechStellarReferenceUnits(SRUs)
Goal:Usescienceimagerstomeasurethehigh-energyradia)onenvironment. Trash?
Treasure!
Opportuni4es:Juno• MissionOverview:Juno– JOI:July2016,nominalsciencetostartDec.2016– Sciencephase:37orbits,20months– Polarmeasurementsàgreaterorbitdiversity– Junoequippedwithdetectorsfor1MeVe-and3MeVp+
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• ThreeinstrumentsareCCDs– JunoColorCamera(JunoCAM)– AdvancedStellarCompass(ASC)– StellarReferenceUnit(SRU)
Junoorbitplan,resul1ngin24°spacingover15orbits.Imagesource:NASA/JPL-Caltech
(Note:ImagemadepriortoJOI.)
JunoInstrumentsandSystems
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Opportuni4es:Europa• MissionOverview:– PhaseBofdesign,Launchdate:~2022– OrbiterandlandertostudyEuropa– Highlyellip)calorbitdesign
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Imagesource:NASA/JPL-CaltechhXp://www.jpl.nasa.gov/missions/europa-mission/
• NodetectorswithdedicatedMeVcapabili)esatall…
• UVS,MISE,EIS,andMASPEXaresensi)vetoMeVelectrons
• Measuredelectronenergyrangedeterminedbyinstrumentshieldingandsensi)vity
• Beamtestsandtransportsimula)onsshouldbeperformedtocalibratetheinstrumentresponsetoradia)on
ApproachandMethodology• TheGalileospacecrahorbitedJupiterfromDecember1995toSeptember2003,comple)ng35orbits.
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Imagesource:NASAhXps://solarsystem.nasa.gov/galleries/galileo-diagram-labeled
Mono-energe4cSims:EnergyDeposited
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Simula4onFluence• 1E9electronssimulated• Spherewithradiusr=150cm• Angulardistribu)on:cosine-law(uniform2πfluxfromaplane)
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f0 =N
4π (4πr2 )=
1×109
4π (4π (150)2 )=1.258×103
90cm
150cm
e-
• Needtomul)plybyafactorof4fortherealenvironment:– Par)clesradiateinwardsandoutwards– Angulardistribu)onisisotropic(whatwouldbeseenfromauniform4πflux)
Units:par)cles/sr-cm2
A B C D E F
Energy [MeV]
#Unique Hits
# Pixels with Hits
Hits to Pixels
Primaries Secondaries Total (B+C) Particle to Pixel Hits (D/E)
1 0 0 0 0 0
3 0 3 11 3 0.27
5 0 16 26 16 0.62
10 48 99 225 147 0.65
30 296 1001 2489 1297 0.52
50 622 2661 6151 3283 0.53
100 1144 7989 18263 9133 0.50
200 1999 20496 44650 22495 0.50
Simula4onRun2
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Ra4oofthenumberofpar4clesreachingthe
detectorandthenumberofpixelswithhits,G1
Numberofpar4clesthatreachthedetector
Numberofpixelswithenergydeposited
WefindG1=0.54±0.056(95%conf.)par)cles/pixel
GalileoEnerge4cPar4cleDetector
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10-minuteEPDintegralcountrate(leD)andomnidirec1onalflux(right)fortheDC3(>11MeV)channelasafunc1onofdistancefromJupiter.Ontheright,thedataarefitwithalinear(inred)andalog-normaldistribu1on(inblue).Thelog-normalaverageareabeXerfittothedata.Imagesource:I.Junetal.,2005
GalileoEPDUncertain4es
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Plotoftheuncertainty(standarddevia1on)ofthera1ooftheobservedfluxtothepredictedfluxasafunc1onofdistance(binnedby1RJ).Imagesource:I.Junetal.,2005.
DistancefromJupiter,RJ,avg
10^STD(11MeV)
7.5 1.2808.5 1.5379.5 1.61610.5 1.74011.5 1.87212.5 1.83913.5 2.27014.5 2.70015.5 2.85416.5 2.75817.5 3.35918.5 2.91519.5 3.06920.5 3.10721.5 2.66722.5 3.40523.5 2.47824.5 2.77425.5 2.99826.5 2.89127.5 2.906
For11MeVintegralflux:
GalileoSSIImagesforAnalysis
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BackupPlans• IfitisnotpossibletoextractanintegralenergychannelfromeithertheSSIorNIMSinstruments(e.g.,theinforma)onextracteddoesnotagreewiththeEPD),wewillaugmentthenullresultwithaddi)onalanalysesofnon-tradi)onalsourcesofradia)oninforma)on.– AnalysisofGalileostartrackerdata(notimages,buthits)
– AnalysisofhousekeepingtelemetryfromGalileo– AnalysisofGalileo'sUltra-StableOscillators(USOs).USOfrequencyshihscorrespondtoradia)ondose.
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GalileoSSIOpera4onandModes
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• Fourimagingmodes:
• Eachframehasa“prepare”and“readout”opera)on.• Exampleof8-2/3smode:
ImagingModes 2-1/3s 8-2/3s 30-1/3s 60-2/3s
PrepareTime 2/3s 2s 3-2/3s 7-1/3s
ReadoutTime 1-2/3s 6-2/3s 26-2/3s 53-1/3s
FilterStepsAllowed 1 2 3 7
Prepare:2seconds
Readout:6-2/3seconds
Claryetal.,1979