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Publié par | technische_universitat_munchen |
Publié le | 01 janvier 2006 |
Nombre de lectures | 25 |
Langue | English |
Poids de l'ouvrage | 42 Mo |
Extrait
TechnischenUniversit¨atM¨unchen
Fakult¨atf¨urPhysik
Institutf¨urExperimentalphysikE21
Quantitativetimeresolvedneutron
imagingmethodsatthehighfluxneutron
IFRM-Isource
BrunnersneJohan
Vollst¨andigerAbdruckdervonderFakult¨atf¨urPhysik
derTechnischenUniversit¨atM¨unchenzurErlangungdesakademischenGradeseines
DoktorsderNaturwissenschaften
.ertationDissgenehmigten
Vorsitzender:Univ.Prof.Dr.M.Kleber
Pr¨uferderDissertation:1.Univ.Prof.Dr.P.B¨oni
2.Univ.Prof.Dr.W.Petry
gereicDiehtunDissdduertatrchiondiewuFrdeakuamlt¨atfu¨r19.09.2005Physikbameid01er.Tec03.2006hnischenangenommUniveren.sit¨atMu¨nchenein-
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English
Inthecurrentworkvariousnewexperimentalmethodsandcomputationprocedures
inthefieldofneutronimagingarepresented.Thesemethodshaveasignificanttechnical
importanceinnon-destructivematerialinvestigations.
Withstroboscopicneutronradiographyperiodicprocessescanbeinvestigatedonasub-
millisecondtimescale.Thisopensgreatopportunitiesforthestudyandthedevelopment
ofcombustionengines.
Energyselectivetimeofflightneutronradiographyatneutronspallationsourcesuses
theenergydependenceoftheneutroncrosssectiontodistinguishbetweenmaterials.The
energyresolutionofthistechniqueisverygoodandallowstheidentificationofspecific
ials.rmateSoftwaretoolsforneutronradiographydataevaluationanddatavisualizationwere
programmed:calibrationalgorithms,imagedeconvolutionprocedures,toolsforimage
assessment,agraphicaluserinterfaceforfastdatainspectionandmanybatchprocessing
routinesforlargeneutronradiographyimageseries.
Thedevelopedmethodsandsoftwaretoolsareinuseattheneutronradiographyand
tomographyfacilitiesatnewresearchreactorFRM-IIinMunich,Germany.
enfassungusammZ
hDeutsc
IndervorliegendenArbeitwerdenverschiedeneneueexperimentelleMethodenund
RechenverfahrenausdemGebietderRadiographieundTomographiemitNeutronen
vorgestellt.DieseDurchstrahlungsverfahrengewinnenzunehmendanBedeutungfu¨rdie
zerst¨orungsfreiePru¨fungvonneuenMaterialien.
MitderstroboskopischenNeutronenradiographie-Methodek¨onnenperiodische
ProzesseaufeinerSubmillisekunden-Zeitskalauntersuchtwerden.Daser¨offnetviele
verheißungsvolleM¨oglichkeitenf¨urdasStudiumunddieWeiterentwicklungvonVerbren-
nungsmotoren.
Dieenergieaufgel¨osteFlugzeit-NeutronenradiographieanNeutronen-
Spallationsquellenn¨utztdieEnergieabh¨angigkeitderSchw¨achungskoeffizientenaus,um
zwischenverschiedenenMaterialienzuunterschieden.DurchdiehoheEnergieau߬osung
dieserMethodewirddasgezielteSuchennachbestimmtenMaterialienineinem
unbekanntenObjektm¨oglich.
Softwarewerkzeugef¨urdieAuswertungundVisualisierungvonNeutronenradiographie-
Datenwurdenprogrammiert:Evaluierungsalgorithmen,ProgrammezurEntfaltungder
Bildunsch¨arfeundzurKorrekturvonArtefakten,einegraphischeBenutzeroberfl¨achef¨ur
dieschnelleDateninspektion,AlgorithmenzurBestimmungderBildqualit¨atsowieRouti-
nenf¨urdieStapelverarbeitungvongroßenBildserien.
DieneuenexperimentellenMethodenundSoftwarewerkzeugewerdenanden
Neutronenradiographie-und-tomographieanlagenamneuenForschungsreaktorM¨unchen
FRM-IIeingesetzt.
Contents
1Physicsofneutronimaging2
1.1Exponentialattenuationmodel.........................3
1.2Effectsofneutronscattering...........................4
1.3Effectsoftotalreflection.............................6
1.4Spectraleffectsinneutronimaging.......................7
1.5MonteCarloSimulations.............................10
ductiontroIn
2
2Experimentalsetupforneutronimaging11
2.1Neutronsource..................................11
2.1.1TheneutronradiographyfacilityANTARESatFRM-II.......12
2.2Neutronradiographydetectors.........................14
2.2.1Scintillators................................15
2.2.2Detectoroptics..............................16
2.2.3CCDcameras...............................17
2.2.3.1LCDshutters..........................18
2.2.3.2InterlinetransferCCDs....................19
2.2.3.3CCDswithimageintensifier.................20
2.2.3.4ShutteredCCDs........................21
2.2.4TheNRdetectoratANTARES.....................22
2.3Theobjectforneutronradiographyandtomography.............23
2.4Imagequality...................................26
2.4.1Apracticalexaminationofimagequality...............27
3Dataevaluationandvisualization33
3.1HardandsoftwarefordataanalysisatANTARES..............33
3.2Artefactcorrection................................34
3.2.1Beamfluctuations............................34
3.2.2Gammaspots...............................34
3.2.3Scintillatordegradation.........................35
3.2.4Lensdistortions..............................36
3.2.5NRdeconvolution............................36
3.3Normalization...................................37
3.4ReproducibilityanduncertaintyofaNRimage................38
3.5QuantitativeNR.................................40
3.6NRdatavisualization..............................42
3.6.1Softwaretoolsfordataevaluationandvisualization..........42
3.6.2Visualizingdifferencesbetweenimages.................44
3.6.3Fusingimages...............................46
CONTENTS
vi
3.7Limitationsbythehumaneye..........................47
4Measurements51
4.1StroboscopicNR:Combustionengines.....................51
4.1.1FirstNRofarunningcombustionengine...............52
4.1.2Carcombustionengine..........................54
4.1.3Injectionnozzle..............................57
4.1.4FirstneutronradioscopyofancombustionengineatFRM-II....60
4.2EnergyselectivetimeofflightNR.......................62
4.3QuantitativeNR:acompressortyperefrigerator...............69
ANewapplication:fossilstone
BVisualizationmethod:DifferenceNRofanoilpump
esfigurofList
yiographBibl
ionsAbbreviat
soncatiPubli
diCompactcs
onsiluscCon
okOutlo
72
76
80
86
87
88
89
90
91
Introduction
whichuNeutronsethepimagingenetrati(NI)onisofaneucollectivtronseteforrmtheforinvnones-tidegationstructivofethetestiningternal(NDTstr)meucturethodsof
anobject.TheuniqueinformationdeliveredbyNeutronRadiography(NR)andNeutron
inTsighomograptintohyhistori(NT)calconandtriarbutcehetoologithcealdevobeljectopmes.ntofhightechproductsandconcedes
appTheliedfirstatNRtheresimearcageshwreaceretortakenFRMinin1940,Garchatingthewithbeginthermalningofandthesoon80’swiththefasmtnethoeudtronwsas.
Withtheuseoflarge2DdetectorsandincreasingcomputingpowertheNImethodsreally
gotestablished.InthelastyearsnewmethodslikeenergyselectiveNR,phasecontrast
NRandmanynewareasofapplicationsopenedup.Highfluxneutronsourcesanda
growinginterestfromindustryandsciencepushedtheactivitiesinthefieldandgavenew
opportunitiesformethodicalimprovements.InthelastfiveyearseightdiplomaandPhD
thesesaboutNIappeared.
Thisworkisdedicatedtonewexperimentalmethodsfortimeresolvedneutronimaging
andmethodsforquantitativedataanalysis.Itconsistsoffivechapters:
attenChapuationter1modstartsel.FwithorathewiderprincipundleersandtanthdinegphofysicsneutofronNRimandagingpresdenevtsiationtheesxpfonromentithale
simplemodellikeneutronscattering,totalreflection,effectsduetothebeamgeometry
andspectraleffectsarediscussed.
faciliThetiesfexporenrieumentrontalsimagingetupofareaaNIvailfacilitable:yisThtreeatedANTinARESchaptefacilitr2.ywAitththaecoldFRM-IneutItwrono
spectrumandtheNECTARfacilitywithafastfissionspectrum.TheANTARESfacility
ispresentedanddescribedfocussingonthebeam,thedetectorandpossibleobjectsof
.estigationvinAmajorpartofthisworkconsistsofnewandpowerfultechniquesforquantitative
evaluationandvisualizationofNRdata(chapter3).Allimportantstepsoftheevaluation
proceWitdurehinarethisdewscrorkibtedwoandnewtheexpesoftriwmareentalm”Neutrethooneydsew”erefordevviseulopedalizationandisapplexpiedlainined.prac-
timeticalofmeasflighutremNR.enInts:chtheapterstrob4boscothopticechneutrniquesonarimeagiintngrodtecucehdniqanduethandeexptheerenimeerngyts,secarlectriedive
outatneutronimagingfacilitiesinEurope,aredescribedandtheirresultsarediscussed.
1erChapt
Physicsofneutronimaging
TheobjectofinvestigationisplacedinawelldefinedneutronbeamI0(x,y)anda2D
pgraposithyionsimageensitiv(1.1).edeteThisctorshadorecordswimtheagetrconansmtaiinstteindforrmadiatationionabinoutensitttheyIin(tex,rynal),sthteructurradio-e
oftheobject.
Figure1.1:Principleofneutronradiography
Forneutrontomography,aseriesofNRimagesfromdifferentdirectionsaremeasured
byrotatingtheobject.Fromtheimagesstackthecomplete3Dvolumeoftheobjectis
reconstructed.Adetailedmathematicaldescriptionofthetomographicreconstructioncan
befoundin[Kak88,0].Thegreylevelsofeachvolumeelement(voxel)correspondtothe
attenuationcoefficientofthatelement’smaterial.Inthiswaymaterialsdifferinginthe
neutronattenuationcoefficientscanbedistinguishedandtheindividualcomponentsofa
multicompositeobjectcanbeseparated.
NeutronimagingiscomplementarytootherNDTmethodsandoftenpermitsanonde-
structiveanalysiswhenothermethodsfail.CharacteristicforNIistheuniqueability
topenetratelargemetallicobjectsandatthesametimethesensitivityforhydrogenous
materials.Inthefollowingsomeexamplesoftypicalapplicationsarelisted:
•penetrationbehaviourofwaterinsoil,wood,stone,concrete,textilesanddevel