CCD based vertex detector design for JLC

CCD based vertex detector design for JLCTsukasa AsoToyama National College of Maritime TechnologyG.Iwai,K.Fujiwara,H.Takayama,N.TamuraNiigata UniversityY.Sugimoto, A.MiyamotoKEKK.AbeTohoku Gakuin UniversityJLC Vertex group

VERTEX2002 in Hawaii Island, Kona

ContentsDesign concepts and RequirementsAccelerator DesignVTX detector designIR design and backgroundsPresent results and ActivitiesRadiation immunitySpatial resolutionFast readout electronicsSummary


AcceleratorDesign6mrad crab crossingBeam time StructureBunch-train StructureI )


VTX DesignVTXPrecise Secondary vertex reconstructionReconstruct decay vertices of B and D meson decays for excellent b/c jet separation Improvement of momentum resolutionRequirementsUnambiguous 2D reconstructionPixel devices If the hit rate of background was about 1hit/mm2/train, It correspond to 100% occupancy in Strip detector 1hit/(20um x 5cm)/train.Low materials(Especially for low momentum tracks)Thin devicesSimple structure/operation Operation at room temperature ~ 0 Celsius.


Room temperature operationCCDsFeatureThin/Low materialLow power consumptionBut Needs cooling ?w/o Cooling system Avoid multiple scattering by cooling systemAvoid thermal distortion of sensors ( fabrication operation temperature discrepancy)Desirable to operate in room temperature ( ~ 0 Celsius )Back-illumination CCD : HPK S7170 Thickness ~20umCCD Flatness


VTX detector designBaseline design |cos | < 0.90Pixel size 25 um1.25cm x 5cm x330um4Layers with 10deg tilt ( r=24,36,48,60 mm) ( Ladder 16/24/32/40) (Sensor 2/3/4/5)Intrinsic resolution 4 um (Just for a Simulation input )


IR Design and BackgroundModel d) 3T with SC-QC1QC1 : Super Conducting magnet L* = 4.3 m To reduce back scattering background produced by the interaction at QC1R=8~16.5cm


Background estimationBeam-Beam Interactione+e- pair productionBeamstrahlung Secondary produced backgrounds*Geant4 ( SR/PhotoNuclear )Include solenoid ( uniform 3T ) +QC1 ( Ideal gradient ) Electron backgrounds ( /mm2/train)**Geant395bunchesLow Lum.Similar toTRC(X)NLC - JLCNeutrons Previous Study 1E+9/cm2/Yr (Beamstrahlung)1Yr operation e+e- pair ~1hit/mm2/train1.5E+11/cm2/Yr


Present results and ActivitiesRadiation immunitySpatial resolutionFast readout electronicsII)


Radiation ImmunityMPP OperationInverted by holesSi02 Si InterfaceSmall packetNotch CCD2-Phase CCD3-Phase CCDLow density


CCD Structure [contd]

Result > 1.5E+11e/cm2JLC: 1.5E+11/cm2/yr @2.4cmResult > 1.5E+10 n/cm2JLC: 1E+9/cm2/Yr (Preliminary)Radiation ImmunityVee (V)Vee (V)Dark current (electrons/pix) Electrons from Sr90Neutrons from Cf252HPK10


Radiation Immunity CTI properties3Phase2PhaseStdCTINotchVCTI ( Irradiation)CTI ( Irradiation)ElectronNeutronHPK10CTI~Nt/Ns Concentration Nt : Defect Ns : Signal


Radiation test -1-Why is additional test of radiation damage needed?

Non-Ionizing Energy LossRadiation damageis thought to be proportional to NIEL

The radiation damageat JLC estimated to be10 times bigger thanour study using Sr90.

Radiation damage by high energy (>10MeV)electrons should be studied.


Radiation test (First trial 2002/12/9)Experimental setup

ElectronBeam100 MeVPt 0.1X0 0.5X0Bending MagnetChoice of SettingsPrimary Beam Energy 100MeV electronsTarget radiation length 0.1/0.5 X0B field High/Low Tesla modeTohoku-Univ


Spatial resolution-Test beam-Dark current is suppressed by the successfulOperation of Inverted mode. Noises in a pixel (R/O cycle ~ 3sec. ) HPK10(23e)/ HPK50(58e) / EEV(37e)HPK50 : HPK with epitaxial layer of 50um4-Layers CCD Tracker


Spatial resolutionIntrinsic ResolutionIs better than 3 um. Thermal diffusion of signal charge improves resolution. RLM : RLM functionAC : Analog centered Pixel APixel BSignal of Pixel ASignal of Pixel B


Comparison with simulationEnergy Deposit in Silicon Estimated Active layer11um for HPK1051um for HPK50Active Layer


Charge sharing simulationHPK10HPK50d/A=50%d/A=30%d/A=20%d/A=10%d/A=5%Depletion (d)Field Free (f)Active (A=d+f)XXLog(R)Log(R)d ~ sqrt(2Dt)f ~ G.R.HopkinsonNIM 216(1983)432Energy(keV)NNClusteringHPK50HPK10OpenExpCloseSimDrift coff. *Drift Time


Electronics fabricationReadout operationAll pixels must be readout every train crossing interval of 6.7 ms.10MHz readout can transfer about 250x250pix in the interval.5cm1.25cm250x250pix/chip16chips/sensor

Total 424 sensors6784chips needed.


Fast R/O System -1-

Evaluation board of ADCCCD Signal processor chip for Digital Camera 9x9mm2 chip size ~ $6/chipAD9844A(Analog Devices Co.)12bit 20MSPS ADC20MSPS Correlated Double Sampler6bit variable CDS Gain Amp.Low power consumption(65mW/2.7V)


Fast R/O System -2-CCD SIGNALVIDEO SIGNALAD6644 inputLVDS InputXC2V404CS144C(FPGA)AD9844A[FADC]Backside Interface to Digital board (12 bit DBUS]Linearity was confirmed.LSB resolution 0.2mV.Dynamic range 0~800mV


SummaryDesign and status of JLC VTX detector is presented.Goal --- CCD operation at room temperatureRadiation immunity : No problemBut, further investigation is necessary. Electrons => Higher energy must be confirmed experimentally. ( Additional experiments are going. ) Neutrons => Yield of neutron is ambiguous ( beam dump ) ( Reliable simulation with precise geometry, JUPITER)Spatial resolution : < 3um at -15 C.More investigation of charge sharing property improve resolution? ( Laser scanner test at Niigata Univ. with 2x2um spot.)Readout Electronics: EvaluatingStudy the effect of Fast readout for irradiated samplesEvaluation of thinned devicePartially thinned CCD ..(Distortion measurement system: ready)


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CCD based vertex detector design for JLC