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					ATLAS SCT Endcap Detector Modules




                                Lutz Feld
                              University of Freiburg
            5.6m       for the ATLAS SCT Collaboration

                              Vertex 2002
Endcap Disks covered by 3 Rings of Modules


                                                             cooling block
    outer modules



    middle modules
     (on backside)
                                                             power tapes

      inner modules

•   9 disks in each endcap, ~1.2m diameter CF structure
•   132 detector modules on a full disk, 1976 endcap modules in total
•   modules have central mounting and cooling point module overlap easy
•   each module serviced by a power tape and 3 optical fibres
•   evaporative cooling circuits serve up to 13 modules
Vertex 2002                 Lutz Feld, Freiburg University                   2
3 Module Types



              outer module                                           inner module
              (52 per ring)                                          (40 per ring)




                                                     middle module
                                                     (40 per ring)




Vertex 2002             Lutz Feld, Freiburg University                               3
Endcap Module Design: Silicon Sensors

                                                 4 wedge shape
                                                 silicon sensors

                                                 768 p-in-n strips,
                                                 single sided

                                                 supplied by
                                                 Hamamatsu and
                                                 CiS

                                                 sensor
                                                 alignment < 5µm

                                                 40mrad stereo
                                                 angle



Vertex 2002     Lutz Feld, Freiburg University                 4
Endcap Module Design: „Spine“



                                                         sensors are
                                                         glued to „spine“:

                                                         TPG bar for heat
                                                         removal
                                                         (1700 W/m/K)

                                                         AlN wings for
              mounting points and cooling contacts       mechanical
                                                         stability




Vertex 2002             Lutz Feld, Freiburg University                5
Endcap Module Design: Hybrid
12 ABCD3TA            hybrid connected to sensors
binary read-out       only by fanins  thermal split
chips (DMILL)




hybrid:
flex circuit on
carbon-carbon




Vertex 2002       Lutz Feld, Freiburg University       6
Hybrid
• development of hybrid was critical and
  needed several iterations

• very low impedance is key for successful
  operation of binary ABCD chips

• requirements:
      • double sided, 12 readout chips
      • supply well filtered analogue/digital power
      • com/data lines and drivers for optical link
      • detector bias supply (up to 500V)
      • heat removal (7W)
      • low mass

• implementation:
      • 6 layer copper/Kapton flex circuit
      • ~75µm feature size, ~3000 micro vias
      • flex folded around carbon-carbon
        substrate
      • full assembly and basic testing in industry


Vertex 2002                      Lutz Feld, Freiburg University   7
Thermal Performance of Endcap Module
• evaporative C3F8 cooling system, capable to cool down to –30°C

• central module cooling block, split between hybrid and detectors,
  long modules have additional far end cooling block

• detailed simulations, confirmed by measurements of non-irradiated and
  irradiated modules on an evaporative cooling test rig
              detector temperature vs. radiation damage for coolant at –21°C
                           inner module                                              outer module




 expected after 10 years                                   expected after 10 years
Vertex 2002                        Lutz Feld, Freiburg University                               8
Electrical Performance
• binary front-end chip  occupancy vs. threshold  „s-curves“

• signal height and noise are derived from „s-curves“

• relevant for operation: hit efficiency and noise occupancy

• noise occupancy determined by
      – front-end noise (fixed for given ASIC and detector)
      – channel-to-channel threshold variations (threshold trim per channel)
      – additional noise: common mode, feedback etc. (the difficult part...)

occupancy vs. channel and threshold                         occupancy vs. threshold




Vertex 2002                    Lutz Feld, Freiburg University                         9
16 Prototype Modules
• 9 outer, 2 middle, 5 inner
                                                        threshold spread
• modules built reliably inside
  tolerances, in several institutes
• noise 1500 e or less
• noise occupancy @1fC: ~10-5
• gain ~50mV/fC
• threshold spread 150 e


       ENC noise                                        gain




Vertex 2002                    Lutz Feld, Freiburg University              10
System Test: 4 Modules on a Disk Sector
              noise for each chip when operated
              simultaneously
              singly




        common mode noise

                                                                  with 4 modules on disk
                                                                  • no extra noise
                                                                  • common mode noise
                                                                    negligible


Vertex 2002                      Lutz Feld, Freiburg University                            11
Testbeam Results
• binary read-out: efficiency and noise occupancy at given threshold

• spec: single hit efficiency > 99% while noise occupancy < 5E-4

• long modules before / after irradiation to 1.6 or 3.3 E14 24GeV-p/cm2
  in a beam of 180 GeV pions

• 10 years LHC operation ~2.6 E14 p/cm2
non-irradiated            1.6E14 24GeV-p/cm2                3.3E14 24GeV-p/cm2
@ 150V bias               @ 480V bias                       @ 480V bias




• spatial resolution of 23µm achieved, as expected from pitch/sqrt(12)
Vertex 2002                Lutz Feld, Freiburg University                        12
Summary & Outlook

• ATLAS SCT endcap modules final design review in August 02




• now preparing for production of 2000 modules (+spares):
      – ASICs and detectors: ~80% delivered
      – hybrid: pre-series of 100 pieces in production, first samples delivered;
        for production: full assembly and basic testing in industry
      – spines and fan-ins: pre-series in production, first samples delivered;
        production can start soon

• module assembly and QA at 7 sites
      – good experience with assembly of prototype modules (>20)
      – preparation of production tooling and qualification over next months
      – production will take about 1.5 years




Vertex 2002                     Lutz Feld, Freiburg University                     13

				
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posted:6/8/2013
language:English
pages:13