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Material developments for the HL-LHC upgrade of the CMS tracker

Material developments for the HL-LHC upgrade of the CMS tracker . 19 January 2012 Joachim Erfle University of Hamburg. Overview. The tracker and its challenges at HL-LHC Some layout possibilities for a new tracker and sensor modules The basic working principle of silicon sensors

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Material developments for the HL-LHC upgrade of the CMS tracker

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  1. Material developments for the HL-LHC upgrade of the CMS tracker Material developments for the HL-LHC upgrade of the CMS tracker 19 January 2012 Joachim Erfle University of Hamburg

  2. Material developments for the HL-LHC upgrade of the CMS tracker Overview • The trackeranditschallengesat HL-LHC • Somelayoutpossibilitiesfor a newtrackerandsensormodules • The basicworkingprincipleofsiliconsensors • A campaignto find thenexttracker‘ssensor material • First resultsofthiscampaign

  3. Material developments for the HL-LHC upgrade of the CMS tracker The currenttracker • Over 200m2activesilicon • About 26000 sensors • 9.6 millionstripchannels + 66 millionpixelchannels

  4. Material developments for the HL-LHC upgrade of the CMS tracker Challengesforthetrackerat HL-LHC • Requiredfeaturesfor HL-LHC: • Higher radiationtolerance • More (smaller) channelsfor a loweroccupancyat high pile-up • Trigger informationforlevel 1 New trackerneeded

  5. Material developments for the HL-LHC upgrade of the CMS tracker Twopossiblenewsensormodulelayouts courtesyofS. Mersi, CERN courtesyofS. Mersi, CERN

  6. Material developments for the HL-LHC upgrade of the CMS tracker Possiblenewtrackerlayout courtesyofS. Mersi, CERN

  7. Material developments for the HL-LHC upgrade of the CMS tracker Strip sensors Basic layoutof a stripsensor Depletionof a n-bulksensor • Basicallytwo different types: • N dopedbulk: • Holes readout •  slower • Easiertoproduce • Tendstoundergotype inversion • P dopedbulk: • Electronreadout •  faster, lesstrapping • Harder toproduce Depletionof a p-bulksensor

  8. Material developments for the HL-LHC upgrade of the CMS tracker Radiation damage in silicon • Twotypesofradiationdamage: • Surfacedamage • Bulkdamage mainproblemforhadronicirradiation • Subdivided in threedamagetypes: courtesyofM. Moll, UHH CERN Reduceschargecollection Increasesleakagecurrent Changeseffectivedopingconcentration  fulldepletionvoltage

  9. Material developments for the HL-LHC upgrade of the CMS tracker Goals ofthe HKP-campaign • The mainchallengesforthetrackeratthe HL-LHC will be: • Higher radiation dose (upto a fluenceofΦeq= 1016 cm-2) • Higher occupancy • The currenttrackerwould not withstandtheradiationand also developoccupancyproblems • → Find bestbestsuitablesilicon material andlayoutfor a futuretrackingdetector • Toachievethatweinvestigate a large varietyofmaterials: • Different oxygen, carbon,… content • Different bulkdoping (n and p) • Test sensor geometries andlayouts • Irradiationswithneutronsor/andprotonstosimulate HL-LHC radiation dose

  10. Material developments for the HL-LHC upgrade of the CMS tracker Wafer overview: HPK-campaign

  11. Material developments for the HL-LHC upgrade of the CMS tracker Silicon material • Ofeach material thereare 3 different types: • n-type (N) • Two different stripisolationtechnologiesfor p-bulk: • p-type with p-stop (P) • p-type with p-spray (Y)

  12. Material developments for the HL-LHC upgrade of the CMS tracker Wafer-Processing (deep diffusion) • At high irradiation thick sensors not fully depletable • Mean free path of charge carriers severely reduced due to trapping for highly irradiated sensors • → In thin sensors less charge is trapped and • voltage needed for full depletion is lower. • Standard method for thinning: wafer bonding of Si to Si-substrate (low ohmic) • Well known process • Relatively expensive • New method: deep diffusion • Active volume of a 320μm wafer reduced by diffusing high doping from the back. activevolume inactivevolume activethickness pn-junction physicalthickness

  13. Material developments for the HL-LHC upgrade of the CMS tracker SequenceofMeasurementsandirradiations courtesyof A. Dierlamm, KIT HL-LHC: Lint=3000 fb-1 Prequalification First irradiation Single irradiationqualification Second irradiation Measurementsand time development ofdefect (annealing) studies courtesyofS. Müller, KIT

  14. Material developments for the HL-LHC upgrade of the CMS tracker Irradations HL-LHC: Lint=3000 fb-1 • Neutrons: 1 MeV (TRIGA Reactor Ljubljana) • Protons: 23 MeV (Karlsruhe cyclotron) courtesyofS. Müller, KIT

  15. Material developments for the HL-LHC upgrade of the CMS tracker Volume current versus fluence protons neutrons neutrons protons currentsaremeasured after annealingof 10 min@ 60°C at 0°C andscaledto 20°C J. Erfle, UHH Currentsmatchexpectedvaluefromliterature (M. Moll‘sthesis) withintheuncertainties. -> dose measurementsare ok.

  16. Material developments for the HL-LHC upgrade of the CMS tracker Type-inversion andtheeffectivedoping Partlydepletedsensor, not type inverted • Defectsclosetothebandgapperformlikedopants, so theychangetheeffectivedopingbyproviding a freeelectronor hole • Influence on: • Fulldepletionvoltage • Type ofbulkdoping • Possibleproblems: • fulldepletionvoltagecanriseabovethevaluethatcanbeapplied • Ifthathappens in the type invertedcase, thechargemeasurementisdisturbed Effectivethicknessreduced, but fullyfunctional Partlydepletedsensor, type inverted Readoutchannelsaresomewhat „isolated“ fromcollectedcharge

  17. Material developments for the HL-LHC upgrade of the CMS tracker Nefffor different materials / irradiations n-type protons J. Erfle, UHH neutrons J. Erfle, UHH capacitancesaremeasuredat 0°C, 1kHz after annealingof 10min@60°C All measured n-type materials (FZ andMCz) are type-inverted after neutronorprotonirradiation.

  18. Material developments for the HL-LHC upgrade of the CMS tracker Nefffor different materials / irradiations n-type p-type protons J. Erfle, UHH J. Erfle, UHH neutrons J. Erfle, UHH capacitancesaremeasuredat 0°C, 1kHz after annealingof 10min@60°C J. Erfle, UHH All n-type materialsundergo type inversion No p-type material undergoes type inversion All p-type materialsshow a steepincrease in Neffandthereforedepletionvoltage

  19. Material developments for the HL-LHC upgrade of the CMS tracker Time resolvedchargecollectionmeasurementwith TCT shows type inversion Front Rear E red depth FZ320N - holes - electrons FZ320P courtesyof J. Lange unirradiated p@3E14 Laser: 672 nm, red 3µm penetrationdepth courtesyof T. Pöhlsen, UHH courtesyof T. Pöhlsen, UHH not type inverted U=600V type inverted U=300V type inversionof FZ andMCz n-type materialsisconfirmedby TCT. Signals aremeasuredat 0°C, after annealingof 10min@60°C

  20. Material developments for the HL-LHC upgrade of the CMS tracker CCE ofdiodes, after p@3E14 infrared redlaser, front injection infraredlaser courtesyof J. Lange unirradiated p-type: hole collection n-type p-type n-type: electron collection courtesyof T. Pöhlsen, UHH courtesyof T. Pöhlsen, UHH measurementsareperformedat 0°C and 600V, with 20ns integration time infraredlaser: CCE isabout 90% Electronsonly: CCE ~ 85%, holescollectiononly: CCE ~ 67% Electronreadoutperformsbetter

  21. Material developments for the HL-LHC upgrade of the CMS tracker Signal of FZ320P babysensor, after p@3E14 Signal inducedby a 90Sr source, readoutbyALiBaVa Vdepl CCE of FZ320 p-type isabout 87% at p@3E14, comparedto non-irradiated measurementsareperformedat -20°C courtesyof K. Hoffman, KIT

  22. Material developments for the HL-LHC upgrade of the CMS tracker Idea to reduce occupancy and increase resolution To be able to read out from the sides, inner strips are routed out in the first metal layer Some experimental structures Strip-sensor with integrated Pitchadapter in the first metal layer Strixel-sensor • Pitchadapter needed for readout-chip connection • Is it possible to integrate it on the sensor without loosing active area? courtesyofA. Kornmayer, KIT

  23. Material developments for the HL-LHC upgrade of the CMS tracker First results for integrated pitch adapter courtesyofA. Kornmayer, KIT courtesyofA. Kornmayer, KIT Electron from a Sr90-source at different positions Reduced S/N in PA-region, noise stays constant Flat S/N in standard region of about 17

  24. Material developments for the HL-LHC upgrade of the CMS tracker First results for strixelsensors Electron from a Sr90-source at near area Electron from a Sr90-source at far area 1. far neighbour 1. near neighbour 1. near neighbour 1. far neighbour Seed strip (near) Seed strip (far) 1. near neighbour Signal in the far area only measured on strips in the far area. Signals in near area appear also on far strips 1. far neighbour courtesyofA. Kornmayer, KIT Seed strip (far)

  25. Material developments for the HL-LHC upgrade of the CMS tracker Conclusions • HL-LHC: CMS needscompletelynewtrackingdetectors: • Higher granularity • More radiationtolerance • HPK-campaign to identify Si-material, polarity, sensor-layout • First results: • Diode currents increase as a function of fluence as expected • Neff shows: • - type inversion for all n-type materials • - no type inversion for p-type, with steep increase • Not expected: • CCE with baby sensors and diodes reduced to ~90% after 3E14 proton irradiation

  26. Material developments for the HL-LHC upgrade of the CMS tracker Outlook • More irradiations to come: Higher fluences! • Trying to understand material properties in detail • Full annealing studies to be done •  Definethe material andlayouttobeused in the Phase II upgrade ofthetracker ThankYou !

  27. Material developments for the HL-LHC upgrade of the CMS tracker Backup

  28. Material developments for the HL-LHC upgrade of the CMS tracker CCE of FZ320 after protonirradiation courtesyof T. Pöhlsen measurementsareperformedat 0°C

  29. Material developments for the HL-LHC upgrade of the CMS tracker TCT pulses – p-type FZ200P FZ320P MCZ200P courtesyof T. Pöhlsen courtesyof T. Pöhlsen courtesyof T. Pöhlsen 300V 600V 250V measurementsareperformedat 0°C, using a redlaser not type inverted

  30. Material developments for the HL-LHC upgrade of the CMS tracker TCT pulses – n-type FZ200N FZ320N MCZ200N courtesyof T. Pöhlsen courtesyof T. Pöhlsen courtesyof T. Pöhlsen 300V 300V 200V type inverted measurementsareperformedat 0°C, using a redlaser

  31. Material developments for the HL-LHC upgrade of the CMS tracker oxygencontent

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