E第3章-光电子发射探测器

Chapter3

Photoelectricemissiondetector6/19/20251Photoelectricemissiondetector(VacuumPhotodetector)PhototubeandPhotomultipliertubeCharacteristicsandapplicationofmultiplierphototube

6/19/20252§3-1PhotoelectricemissioneffectEinsteinequation6/19/202533.1.1PhotoelectricemissionofmetalEFEAT=0T>0EnergydistributionofelectronSurfacebarrierEFermienergylevelT＝0：6/19/20254EFEAT=0T>0EnergydistributionofelectronSurfacebarrierEFermienergylevelT>0：6/19/20255Superperformance：lowreflectancemoderateconductanceofcathodealotofemissioncenterlittleescapepower3.1.2Photoelectricemissionofsemiconductor6/19/20256Emissionprocessofsemiconductor1.AbsorptionofphotonIntrinsicemission:η－－20％－30％Impurityemission:η－－1％freecarrieremission:negligible6/19/20257

2.photoelectronmovingtosurfaceLatticescattering,collisionwithvalenceelectronAbsorptioncoefficientEg6/19/202583.Againstsurfacepotentialenergytoescape6/19/20259Classifyofphotoelectricemissionmaterial：PuremetalmaterialAdulteratedmetalorsemiconductorPhotoelectriccathodefunction：§3-2Materialofphotoelectricemission

6/19/2025103.2.1PrincipalParametersofPhotoelectricCathode1.Luminoussensitivity（luminoussensivity／chromalightsensitivity／spectrumsensitivity）（1）Luminoussensitivity:

μA/lm。6/19/202511

(2)Chromalightsensitivity(blue:QB24,red:HB11,infrared:HWB3)wavelength/nmtransmissivity/%6/19/202512

(3)Spectrumsensitivity:

mA/WorA／W

6/19/2025132．Quantumefficiency6/19/2025143．SpectrumresponsecurveS----λQ----λ4．Thermoelectronemission10－16～10－17Acm－26/19/2025153.2.2NormalPhotoelectricEmissionMaterialConditions(1)Lightabsorptioncoefficient(2)Transmissionenergyloss(3)Surface-potentialbarriermetalsemiconductor6/19/2025161.Ag-O-CsphotocathodewwwwwwCsatominternalabsorptionatom6/19/2025172．SinglealkaliantimonidephotocathodeAlkalimetals－Sb，Pbplumbum,Bi,Ti6/19/2025183．Muti-alkaliantimonidephotocathode4．Violetphotocathode“Solarblind”photocathodeCeTe(0.32μm)andCeI(0.2μm)6/19/2025193.2.2Negativeelectronaffinity(NEA)MaterialPositiveelectronaffinity(PEA)photocathodeNegativeelectronaffinity(NEA)photocathode6/19/202520EA1Ec1Ef1Ev1E0EA2Ec2Ef2Ev2Si（Ptype）Cs2O（n

type）Ec1EfEv1Ev2Ec2EA2EdEA1E0SurfacedepletionlayerElectronaffinity

EA1>0Electronaffinity:

EA1=EA2-Ed<06/19/202521CharacteristicsofNEAmaterial：

(1)Highquantumefficiency(2)InfraredspectrumresponseandhomogeneousresponsivityLongwavelengththresholdofPEALongwavelengththresholdofNEA6/19/202522(3)Littlethermoelectronemissionandlittlenoise(4)Photoelectronenergyconcentrate(5)Spectrumresponsibilityeven6/19/202523Normalphotocathode：GaAs/InGaAs/GaAsPSpectrumcharacteristicscurve：HighquantumefficiencySpectrumeven0.50.70.91.10.10.5151050Wavelength/μmQuantumefficiency

/％Ag-O-CsGaAsIn0.12Ga0.22AsIn0.06Ga0.94As6/19/202524§3-3Photomultipliertube(PMT)V0RLaD10D8D6D4D2D1D3D5D7D9-200-400-600-100-300-500-700-900-1100-800-1000-1200DKelectronRvConfiguration:photoelectriccathode,electronopticsfocussystem,interdynode,anode6/19/202525K－photoelectriccathodeD－concentrationelectrode,electronopticsfocussystemD1~D10－

interdynodea－anode3.3.1PrincipleofworkofPhotomultipliertube6/19/2025263.3.2

ConfigurationofPhotomultiplierTubephotoelectriccathode,electronopticsfocussystem,interdynode,anodeFunctionofelectronopticsfocussystem

(1)Focusing(2)Increasethespeedofresponsibility6/19/202527Electronopticsfocussystem16/19/202528Electronopticsfocussystem26/19/202529Electronopticsfocussystem36/19/202530ConfigurationofinterdynodeNon-focusingtypeFocusingtype6/19/202531Configurationofinterdynode

1LouverfanmeshSubtransparenthphotocathodeanode6/19/202532Configurationofinterdynode2Box——meshworkConfigurationmeshfocusingelectrode6/19/202533Non-focusingphotomultipliertubeDefinitionCharacteristics①highefficiencyofinterdynode②independentwithadjacentinterdynodevoltage③longresponsetime6/19/202534Configurationofinterdynode3Straight-linefocusingconfigurationfocusingelectrode6/19/202535Configurationofinterdynode4Squirrel-cagedynodedisadvantagemask6/19/202536AnodeofPhotomultiplierTubeMeshstructuremashanodelastinterdynodeSecondaryelectronprimaryelectron6/19/2025373.3.3

BasicnatureparameterofPhotomultiplierTube1．Sensitivityandspectrumresponsibility

Cathodesensitivity

SK：(μA／lm)

AnodesensitivitySa：

(A／lm)

6/19/202538Cathode

currentspectrumresponsibilityRK(λ)

Anode

currentspectrumresponsibilityRa(λ)CathodeintegralcurrentresponsibilityRKAnode

integralcurrentresponsibilityRA6/19/2025392.Dark-currentCause：(1)Thermoelectronemission(2)Leakagecurrentbetweeneletrode(3)Feedbackeffectbetweenionandlight

(4)Fieldemission(5)Radiosotopeandcosmicradiation6/19/202540Themethodtoreducedark-current：ChoosemoderatevoltagebetweenelectrodeOtherwise：①addreverseddirectcurrenttocompensate②filterdark-current③refrigerant6/19/2025413．Volt-amperecharacteristics(1)Cathodevolt-amperecharacteristics6/19/202542(2)anodevolt-amperecharacteristics6/19/2025434.linearityThecauseofnonlinearity：①internalcause——thechangeofspacecharge,resistanceofphotocathode,focusingandgatheringefficiencyetal②externalcause——degenerativefeedbackandreassignmentofloadresistance6/19/2025445.stability(1)Sensitivityslowdriftworking-hours/hrelativeanodecurrent/%6/19/202545(2)Hysteresiseffectanodecurrent/%time/minlightpulsecurrentpulsetransit-timetrtransit-timets6/19/202546(3)aging(4)fatigue6/19/202547

6．Timecharacteristicsandfrequencycharacteristics(1)risetime(2)transit-timetransit-time90％10％risetime光脉冲电流脉冲lightpulsecurrentpulse6/19/2025487.MagneticfieldcharacteristicsRelativesensitivity(%)Magnetic(T)×1046/19/202549ThemethodtoreduceexteriormagneticfieldDegreeofmagneticmask(%)

6/19/202550

8．Spaceuniformity6/19/2025519．PolarizationeffectphotoelectriccathodeincidentpolarizedlightRelativeoutput(%)angleofincidentpolarizedlight(o)6/19/20255210.NoiseChiefnoise:ShotnoiseCathodeShotnoiseRMS(Root-mean-squarevalue)AnodeShotnoiseRMS(Root-mean-squarevalue)

6/19/2025533.3.4Material