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D0 Silicon Tracker Replacement for Run 2b SMT-II 2004-2007

D0 Silicon Tracker Replacement for Run 2b SMT-II 2004-2007. Tianchi Zhao May 1, 2001 Tevatron Collider Run 2b D0 Silicon Tracker for Run 2a Radiation Damage and Radiation hard Materials MRI Proposal and Responsibilities D0 Silicon Tracker for Run 2b. Tevatron Operation.

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D0 Silicon Tracker Replacement for Run 2b SMT-II 2004-2007

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  1. D0 Silicon Tracker Replacement for Run 2bSMT-II 2004-2007 Tianchi Zhao May 1, 2001 Tevatron Collider Run 2b D0 Silicon Tracker for Run 2a Radiation Damage and Radiation hard Materials MRI Proposal and Responsibilities D0 Silicon Tracker for Run 2b

  2. Tevatron Operation Run 2a (2001-2003) ~2 fb-1 36x36 (396 ns bunch spacing) until reaches 1032 cm-2sec-1 switch to 140x100 (132 nsec bunch spacing) Peak luminosity 2x1032 cm-2sec-1 Run 2b (2004-2006) ~13 fb-1 150 Rad crossingangle Increase antiproton intensity by 2-3 Peak luminosity 5x1032 cm-2sec-1 TeV33 (2007 and beyond)~10 fb-1 per year Peak luminosity 1033 cm-2sec-1

  3. D0 Run 2A Silicon Tracker 6 Barrels Double-sided + Single sided 12 F-Disks double-sided H-Disks double-sided H-Disks double-sided

  4. D0 Run 2a Silicon Barrel Side-View Layer 1-4 Inner radius 27 mm Outer radius 94 mm Barrel length 762 mm 4 layres- 8 overlapping sublayers

  5. D0 Run 2a Barrel Silicon Tracker

  6. D0 Run 2a Barrel Silicon Tracker Summary Layer 1 Outer 2 barrels 24 single sided sensors Axial Inner 4 barrels 48 double sided sensors Axial + 2o Stereo Layer 3 Outer 2 barrels 48 single sided sensors Axial Inner 4 barrels 96 double sided sensors Axial + 2o Stereo Layer 2 All 6 barrels 72 double sided sensors Axial + 90o Stereo Layer 4 All 6 barrels 144 double sided sensor Axial + 90o Stereo Total number of sensors 432 Total number of channels 387,120 Inner 4 barrels : 8 measurements -> 4 axial, two 2o Stereo, two 90o Stereo Outer 2 barrels : 6 measurements -> 4 axial, two 90o Stereo

  7. Operating voltage limited by breakdown of integrated capacitors

  8. D0 Silicon Tracker Replacement for Run 2b D0 Silicon Track was conceived in early 1990’s (VFD << 100 V) It was designed for ~3 fb-1 Decision made to replace the entire silicon tracker after Run 2a Two inner layers expected to die some time during Run 2b Partial replacement is too difficult to do Time required for a partial replacement it much longer than the 6 month shut down between Run 2a and Run 2b SMT-II project has started at D0

  9. Symptoms of Radiation Damaged Detectors P-type doping level increases as radiation level increases Bulk type inversion (n  p) at 0.4 - 0.6 Mrad Depletion voltage increases after inversion (10’s V  100’s V) Leakage current linearly with radiation -> increased shot noise -> increased heat load Reduced inter-strip isolation and charge collection -> signal reduction -> deep level traps -> under depletion Micro discharges Localized radiation damage : noisy strips

  10. Radiation Damage Machanizm Surface damage to peak at ~100 kRad and effects insignificant SiO2 layer : Positive ion accumulation (VFD increase by 10-20V) SiO2-Si interfaces : new energy levels in band gap Dominate effect Bulk damage due to energetic particles displacing lattice silicon atoms Detailed physics processes for bulk damages are not well understood Doping changes due to nuclear reactions examples: 30Si + n 31Si + 31P + e-n-type 28Si(n,p) 28Al (ET = 4 MeV) p-type 28Si(n,d) 27Al (ET = 4 MeV) p-type 28Si(n,) 25Mg (ET = 4 MeV) p-type Insignificant compared to dislocation defects

  11. Depletion voltage as a function of radiation fluence Neff = (2 si VFD /qw2) Doping type inversion n --> P

  12. Radiation Hard Silicon Material and Process • Oxygen diffused FZ silicon : Most promising • Typical level of oxygen doping in FZ silicon: ~1015/cm3 • Oxygenation can go up to ~1018/cm3 • Effective doping level still ~1012/cm3 • Other materials • Carbon diffused FZ silicon (diffusion too slow) • Tin diffused FZ silicon • Low resistivity FZ silicon • Epitaxy silicon film • Best radiation resistance may be expected for n+ readout strip on • p-type or n-type bulk • Depletion region starts from the n+ strip side • Works better if partially depleted

  13. Calculated oxygen diffusion profile at 1150oC Si diffusion coefficiency @ 2.25 x 10-10 cm2s-1

  14. Comparison: Standard and Oxygenated Silicon Initial effective n-type doping 1-2 x 1012/cm3 (Note: Oxygen doping level up to 1018/cm3) Doping type inversion at particle fluence ~2.5 x 1013 cm-2 (~0.6 Mrad) Rate of p-type doping increase much slower for oxygenated bulk

  15. More on Oxygenated Silicon O2 oxgenation technique was pioneered by a BNL group in 1992 No effects was found after irradiated with 1 MeV neutrons In 1999, RD-48 at CERN found x2 improvement for protons Further investigations made by the BNL group (IEEE NS Vol. 47, No. 6, p1892, Dec, 2000) High O2 concentration : Oxygenation at High T at 1200 oC for 9 days Thermal donors added  = 925 cm Sample #921 Cool down from 550 oC to 350 oC in 3 hours+ No termal doner  = 2300 cm Sample #903 Cool down from 550 oC to 350 oC in 5 minutes Low O2 concentration : 1100 oC for 6 hours Sample #923 No thermal donor effects (low O2 level)

  16. BNL Study Results • Initial VFD similar for #923 and 903 • Initial VFD of #921 is ~2 times higher • VFD increases more slowly for #903 after inversion : High O2 level helps • #921 appears more resistant to radiation than Sample 903. But VFD higher #923 Low O2 level #903 High O2 level without TD #921 High O2 level with TD

  17. Cooling and Radiation Damage Low temperature operation reduces diode leakage current ATLAS silicon @ -7 oC results a x10 leakage current reduction Detector must be kept at low temperature all the time even during shutdown and detector maintains To avoid ‘reverse annealing’ At room temperature, Neff rises after radiation No reverse annealing if below 5-10 oC

  18. Radiation Level for Silicon Microstrip Detectors at Tevatron For best impact resolution, silicon trackers must start as close as possible to the beam have minimum amount dead material before the first measurement Current D0 barrel layer-1 silicon starts at r = 27 mm CDF in Run 2a has added a layer-00 at rmin = 13.5 mm D0 is planning to do the same in Run 2b At r = 13.5 mm 6x1013 charged-particles/cm2/fb-11.5 MRad/fb-1 The inner most layer can get 15-20 Mrad in Run 2b

  19. New D0 Run 2b Silicon Tracker SMT-II Design Constraints Beam pipe parameters Radius of central section ~11 mm (?) (CDF beryllium beam pipe @ $0.25M) Expand to radius starting at z  100 mm (?) Flange radius 20 - 22.5 mm (?) Total length of beam pipe 1520 mm (?) SMT-II Parameters: 13 mm < R < 160 mmBeam pipe r = 11 mm CFT ID = 180 mm Minimum active length : 1.2 m (|| < 2) Maximum installable length as one piece 1320 mm

  20. Problems of D0 Run 2a Silicon Tracker Serious delays, cost overruns caused because of Complicated design Too many different sensor types and hybrids Double sided axial, 2o 90o stereo, different width Single sided different width F, H disks (15o) Vendor technical difficulties and delays double-sided sensors Readout chips and hybrids Low mass cables More than 1 year after the original schedule and after the start of 36x36 collision, only 23% are cabled up and only a few pieces are readout

  21. Layout of D0 Run 2a Silicon Tracker

  22. Silicon Tracker End View(Concept) New SMT-II ID ~25 mm OD ~320 mm SMT-I Barrel ID ~54 mm OD ~200 mm Outer constrained to fit inside fiber tracker L0 sensors mounted on new 1” OD beam pipe

  23. Expected SMT II Performance

  24. Sensor Choice for SMV-II Single sided sensors only Commodity products that can be purchased Radiation hard Much less problems than double-sided Two single sided bonded together for 2D readout Oxgenated n-type FZ silicon bulk p+ strips on n-type bulk Positive high voltage on back plane (n+ side) Back plane AC coupled to ground for signals Break down > 1000 V for inner layers

  25. L2-5 Sensor+Hybrid Modules • Two 12 cm long, 5 chip wide sensors with ~55 mm pitch • Flex circuit hybrid laminated on substrate; wire bonds directly connect sensor to SVX4 readout chips • Do not bond hybrids on silicon as done for SMT-1 • Stereo sensors mounted on opposite side of silicon support

  26. Stave Support Structures • Modules are mounted on “Stave” support structures that run the full length of the tracker • Cooling, low-mass cables run along length of stave • Two different module designs are being investigated

  27. Mechanical and Cooling Issues Stave support (no beryllium bulkheads) Strong outer carbon fiber composite shell Thin inner carbon fiber composit shell Cooling techniques (baseline : water plus glycol) Inner layer requries : -10 to -20 oC Engineering team at Fermilab SiDet actively working

  28. Front End ChipSVX4 SVXIIe used in D0 SMT-I SVXIII used in CDF Run 2a Silicon Tracker SVXIIe and SVXIII use 1.2 m process that is now obsolete Develop SVX4 based on CDF’s SVXIII design LBL/Fermilab Use 0.25 m process that is extremely radiation resistant DC voltage reduced from 2.5 V to 1.25 V Chip will not get much smaller because analog part dominates

  29. Total silicon : ~7 m2 Total number of channels : 947k (SMT-I : 793 k)

  30. Tracker Parameters • Plan to gang two sensors per readout channel for L2-5 • Maximum of 948 readout channels (no ganging of L0-1) • Fits within current DAQ (960 readout channels available)

  31. MRI Proposal to NSF Development of a Silicon Vertex Detector for the Higgs Search at the Tevatron Collider Fresno State UIC (C. Gerber – PI) KU (A.Bean – Project director) K*State (R. Demina – PI) Michigan State Stony Brook Brown (R. Partridge – PI) Washington (G. Watts, H.J.Lubatti – PI) 1.96(NSF)+0.4(foreign) +0.42(match)= $2.78M Covers silicon, chips, electronics and testing for L0-4 and mechanics for L0-1 If successful funding starts 8/01

  32. Institutional Responsibilities and founding Brown IC testing and module assembly $ 327 k Fresno State Hybrid procurement and testing $ 179 k Kansas U Hybrid testing $ 404 k UIC Module assembly $ 200 k Kansas State Sensor procurement and testing $ 320 k Stony Brook Sensor procurement and testing $ 303 k MSU Assembly fixture procurement $ 60 k U Washington Inner layer design and testing $ 165 k

  33. PAC (4/20/01) has advised D0 and CDF to adapt a common design for Run 2b silicon tracker Run 2A CDF Layer-00, 0, 1 Layer-00 is installed on beam pine L00 CDF Inner Layers L00 Rmin = 13.5 mm L0 Rmin = 25.4 mm L1 Rmin = 41.2 mm L0 L1

  34. CDF Layer-00 Construction

  35. Sensor width 8.4 mm and 14.6 mm, Active length 78.4 Implant strip pitch 25 m Implant strip widths of 8 m Readout pitch of 50 m Two sensors are wire bonded together to form pairs Six pairs total along length ~960 mm Hybrids mounted at the ends of the array Fine-pitch kapton cables carry signals from each of the six pairs of sensors CDF layer-00 Laddle

  36. Assembly CDF layer-00

  37. Fine Picth Low Mass Cables for CDF layer-00

  38. Hybrids of CDF Layer-00 at the end

  39. Completed CDF layer-00 Silicon Tracker

  40. Insert CDF Layer-00 in to SVXII

  41. PAC (4/20/01) has advised D0 and CDF to adapt a common design for their Run 2b silicon tracker Current D0 Plan for inner layers Accept CDF inner layer design for Run 2b Improved oxygenated single sided sensors High resolution stereo view for inner layers was not in D0 NSF proposal High resolution stereo (90o) for L0 (was not in D0 NSF proposal) L0 uses 1 and 2 chip wide sensors for axial measurements (only 2 chip wide sensors in D0 NSF proposal) L1 uses 2 chip wide sensors CDF wants to separate inner layers (L0-1-3: r < 6cm) from 3 outer layers D0 current plan is to build L0-1 on beam pipe

  42. Hybrid and Cable for Inner Layers Move hybrids to two ends of the barrel for inner L0 and L1 Reduce sensor damage during construction Ease ladder construction Ease cooling requirement Bring signals from microstrips to hybrids by fine pitch low mass cables Copper and gold traces on kapton 50 m pitch and fanned out to 100 m pitch to reduce capacitance CDF has received new sample cables from Keycom (Japan) They plan to visit Keycom later this year

  43. CDF Run 2b D0 Run 2b Silicon Tracker Design Concepts -Barrel Construction- Long barrel, no disks Simplify construction Interaction region length reduced to  = 12 cm Do not use short barrel construction SMV-I has 6 short barrels Each barrel has two sensor wire bonded together Hybrids glued on top of the silicon sensors Use long ladder construction as done by CMS Long staves (1200 mm for layer-5) Sensors, suport frames, integrated cooling channels, hybrids

  44. A Possible Fall Back Scenario What if Run 2b is on schedule but SMV-II is late? Replace existing beam pipe with a thinner one as planned Build L0 quickly Install layer-0 to substitute dead layer-1,2 Do the full replacement at a later stage

  45. Current D0 Plan for outer layers Reject CDF outer layer approach CDFD0 rmax = 20 cm rmax = 16 cm 9 layers (3 at 40<r<60) 6 layers planned No hybrid in tracking volume Outer layers still has hybrids in tracking volume 100 m readout pitch for L3-555 m readout pitch for L2-5 My opinion D0 should accept CDF’s 100 m readout pitch for the outer layers and also move hybrids to end end of the barrel using pine pitch cables. Some mechanical aspects will have to be different 320 mm OD (D0) vs ~400 mm OD (CDF) 1320 mm installable length limit for D0

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