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Annealing study of a highly irradiated FZ CMS mini sensor with the ALiBaVa setup at KIT

Annealing study of a highly irradiated FZ CMS mini sensor with the ALiBaVa setup at KIT. Robert Eber , Tanja Pfister A. Nürnberg , T. Barvich , W. de Boer, A. Dierlamm , M. Frey, Th. Müller, P. Steck , A. Kornmayer. Overview. Alibava setup at Karlsruhe

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Annealing study of a highly irradiated FZ CMS mini sensor with the ALiBaVa setup at KIT

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  1. Annealing study of a highly irradiated FZ CMS mini sensor with the ALiBaVa setup at KIT Robert Eber, TanjaPfister A. Nürnberg, T. Barvich, W. de Boer, A. Dierlamm, M. Frey, Th. Müller, P. Steck, A. Kornmayer

  2. Overview • Alibavasetupat Karlsruhe • Annealingstudyof a FZ CMS mini sensor • Reverse bias • Forward bias • Leakagecurrent • Signal tonoiseratio • Comparisonofoperatingmodes • Conclusion

  3. ALiBaVa Station at Karlsruhe • Setup shieldedinside a metal box • Daughterboardthermallyisolatedfromsensor • Temperaturerange • Coolingto -30°C • Heatingto +80°C forannealingstudiesinsidethesetup • Signal generationby • Laser 1060nm • 90Sr betasource • XYZ-stage forpositiondependentstudies • Fullyautomatedsoftwareandtemperaturecontrolforcompleteannealingstudy

  4. ALiBaVa Station at Karlsruhe • XYZ stage • Collimatorforsource • IR lasermount • Sensor • Daughterboard • Peltier cooling • Primary cooling • Scintillator • Isolation andshielding

  5. Sensors aboveexpected LHC fluence • Sensor • CMS mini: FZ p-in-n sensor, 295µm activethickness, 192 strips • Irradiation: 7.5E14 Neq/cm2, 25MeV protons (@KA) • Fluenceisequivalenttoaround 10 yearsof LHC operationatradius 4 – 5cm (pixelregion), 300fb-1 • Outerbarrel SLHC stripregion • Annealingstudy • Signal andsignaltonoiseratio • Current • Reverse bias • Forward bias, CID

  6. Reverse biasoperation • Higher collectedcharge • Higher voltage • Lowertemperature • As expected • Sensor at 500V is not fullydepleted • Signal and S/N dropswithlongerannealingtimes 1 ADC ~ 80e- 500V -30°C Noannealing

  7. CID Measurements • Forward bias • Generation ofelectricfieldthroughoutwholesensorvolume • Entiresensordepthis sensitive • Currentfillstraplevelspermanently • Lowerbiasvoltagenecessarytocollectcharges • Landau-Gaussfitswell • Signal • Signal tonoiseratio • Fluence 7.5e14 Neq/cm2and T= -30°C not optimal forCID mode • Investigateoperability [4] [5] -150V-30°CNoannealing

  8. CID Measurements • Signal increaseswithvoltage • S/N showsmaximumatcertainbiasvoltage: • Noise increase • Relatedtocurrent • Overall annealingbehaviour: • Slightdrop in S/N withannealing

  9. Currentannealing Forward bias • Leakagecurrentshowsknownannealingbehaviourwithreversebiasapplied • LC decreases • More impactathighertemperatures • Underforwardbiascondition, currentincreasesdrasticallywithannealing • Noise rises due tocurrent • Operation atlowertemperaturesnecessarytoreducecurrentlevel • Powerful coolingrequired • Currentannealingatfirststeponly Reverse bias

  10. Comparison: CID – reversebias (Signal) • Reverse bias • Signal levelincreasesatlowervoltages after shortannealing • Signal decreaseswithlongerannealing • Forward bias • Annealing has almost no influence on signal height 10d RT annealing Noannealing 100d RT annealing

  11. Comparison: CID – reversebias (S/N) • Reverse bias • Signal to Noise ratioimproved due tobeneficialannealing • Forward bias • Slightdecrease in S/N due tocurrentincrease • Nobeneficialannealingobserved 10d RT annealing Noannealing 100d RT annealing

  12. Summary • Sensor in CID modeoutperformsthesensorwithreversebiaswithnoannealingatonly -150V • Italmostreachesthereversebias 10d at RT annealinglevel • 500V, noannealing, fitswellintoknowndata • 500V, 10d annealingalmostdoublesthecollectedcharge • 1000V, 10d annealingevenperformslikethe n-in-n pixelsat 600V • Noimprovementduringannealing in CID mode References: [1] p/n-FZ, 300µm (-30°C,25ns), strip [Casse 2008] [2] n/n-FZ, 285µm (-10°C,40ns), pixel [Rohe et al. 2005] [3] p/n-FZ, 295µm (-30°C,25ns), strip [Pfister 2010]

  13. Conclusion • Sensor couldbeoperated in CID modewithfluenceof „only“ 7.5e14 Neq/cm2 andtemperature-30°C • CID ispossiblereadoutmode… • Feasible S/N canbeachievedatmuchlowervoltagescomparedtoreversebias • But.. • Applicable in detectorsonlywhen not annealed • Operation atlowtemperatureand high forwardcurrentrequiresvery powerful cooling • Lack ofbeneficialannealingrules out advantagesofforwardbias • Withappropriateannealingthesensorcanresistfluencesabovetheexpectedonesat LHC (300fb-1) • Known FZ p-in-n material couldbechosenforouterbarrelstripregionsat SLHC

  14. Thankyouforyourattention! Diploma Thesis, Tanja Pfister, KIT 2010: IEKP-KA/2010-20

  15. Prof. Max Mustermann - Title References • [4] Beatti, L.J., et al. Forward-bias operating of Si detectors: a way to work in high-radiation environment. Nuclear Instruments and Methods in Physics Research, 439:293, 2000. • [5]Zheng, L. et col. Cryogenic Si detectors for ultra radiation hardness in SLHC environment. Nuclear Instruments and Methods in Physics Research, 579(A):775-781, 2007.

  16. Landau-Gaussfitsat600V, -10°C Signal: NoAnnealing 10d Annealingat RT S2N: NoAnnealing 10d Annealingat RT

  17. Landau-Gaussfitsat -150V, -30°C • Signal: NoAnnealing 10d Annealingat RT • S2N: NoAnnealing 10d Annealingat RT

  18. Current – Voltageat different T

  19. Current – Voltageat different annealing

  20. Clustersignal – Time Plots • Reverse Bias • Forward Bias

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