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Status of the Prototype of the CBM Micro Vertex Detector

Status of the Prototype of the CBM Micro Vertex Detector. M. Deveaux , Goethe University Frankfurt for the CBM-MVD collaboration. Physics goals of CBM. CBM. Important probe: Open charm. M. Deveaux. [W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745]. SIS100

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Status of the Prototype of the CBM Micro Vertex Detector

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  1. Status of the Prototype of the CBM Micro Vertex Detector M. Deveaux, Goethe University Frankfurt for the CBM-MVD collaboration

  2. Physics goals of CBM CBM Important probe: Open charm M. Deveaux

  3. [W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745] SIS100 SIS300 SIS18 Open charm reconstruction: The challenge A collision rate of ~105/s Au+Au is required M. Deveaux

  4. z Target (Gold) Detector2 Detector 1 Primary Beam: 25 AGeV Au Ions (up to 109/s) Primary vertex Secondary vertex Short lived particle D0 (ct = ~ 120 µm) Reconstruction concept for open charm Open charm reconstruction: Concept • Reconstructing open charm requires: • Excellent secondary vertex • resolution (~ 50 µm) • => Excellent spatial resolution (~5 µm) • => Very low material budget (few 0.1 % X0) • => Detectors in vacuum • A good time resolution to distinguish • the individual collisions (few 10 µs) • Very good radiation tolerance • (>1013neq/cm²) Central Au + Au collision (25 AGeV) M. Deveaux,

  5. Sensors for the MVD • Monolithic Active Pixel Sensors • (MAPS, also CMOS-Sensors) • Invented by industry (digital camera) • Modified for charged particle detection since 1999 by IPHC Strasbourg • Also foreseen for ILC, STAR, ALICE… => Sharing of R&D costs. Optimized for one parameter Current compromise M. Deveaux

  6. The MVD for SIS100 Status of FAIR: SIS100 available 2018 SIS300 available later Need SIS300 for open charm production in A-A Physics cases at SIS100 (MVD) • Measure open charm in p-A (p-p?) collisions • Needs ~106 p-Au collisions/s • Measure light vector mesons in A-A collisions • Use MVD as low momentum tracker • Tag and reject conversion pairs => reduces Background • Needs ~104 Au-Au collisions/s M. Deveaux

  7. Running conditions (SIS-100): S. Seddiki, C. Dritsa • Radiation doses per year, incl. factor 3 security margin • Occupancy incl. factor 10 security margin 7 M. Deveaux

  8. Status of the sensor R&D M. Deveaux

  9. Sensor R&D: The operation principle +3.3V Reset +3.3V Output SiO2 SiO2 SiO2 N++ N++ P+ N+ P- 50µm 15µm P+ M. Deveaux

  10. Non-ionising radiation Energy deposit into crystal lattice Sensor R&D: Tolerance to non-ionising radiation +3.3V Output +3.3V GND SiO2 SiO2 GND SiO2 SiO2 N+ P++ P++ N++ P++

  11. Sensor R&D: Tolerance to non-ionising radiation +3.3V Output +3.3V GND SiO2 SiO2 GND SiO2 SiO2 N+ P++ P++ N++ P++ Key observation: Signal amplitude is reduced by bulk damage

  12. Sensor R&D: Tolerance to non-ionising radiation +3.3V Output +3.3V GND SiO2 SiO2 GND SiO2 SiO2 N+ P++ P++ N++ P++ E Electric field increases the radiation hardness of the sensor Draw back: Need CMOS-processes with low doping epitaxial layer

  13. S/N of MIMOSA-18 AHR (high resistivity epi-layer) Mimosa-9 (2005) 20 µm standard epi Preliminary D.Doering, HK 12.8 P. Scharrer,HK 53.13 D. Doering, P. Scharrer, M. Domachowski Safe operation 0.2 x 1013 neq/cm² • Plausible conclusion: Radiation tolerance ~1014neq/cm² reached • Cooling required to operate heavily irradiated sensors M. Deveaux

  14. Sensor R&D: Tolerance to ionisingradiation • Imagers: • Tolerate 1-2 MRad if cooled. • Fast pixels are so far vulnerable: • More transistors • No space for radiation tolerant layout in 0.35µm CMOS. • Current tolerance: 0.5 MRad Pixel withpedestalcorrection ~1000 discriminators M. Koziel, PhD On - chip cluster-finding processor Output: Cluster information (zerosurpressed) • Next steps: Migrate design to 0.18 µm CMOS process • Higher intrinsic radiation tolerance • Less space constraints • Status: First sensor (MIMOSA-32) under test. M. Deveaux

  15. Tolerance to non-ionisingradiation - Annealing MIMOSA-19 imager D. Doering Annealing alleviates ionizing radiation damage substantially No indication for reverse annealing => Recover detector on the fly(?)

  16. MVD-Simulation M. Deveaux

  17. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 17 M. Deveaux

  18. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 18 M. Deveaux

  19. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 19 M. Deveaux

  20. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 20 M. Deveaux

  21. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 21 M. Deveaux

  22. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm 22 M. Deveaux

  23. Global design: How many MVD stations? Open charm in Au-Au 25 AGeV, accepted background tracks per collision. Bad reconstruction Some bad hits Good hits C. Trageser, HK 53.19 Accepted after cut on: p > 1 GeV pt > 0.3 GeV Impact parameter Not applied: Secondary vertex cut Impact parameter of mother particle Adding a third station might improve system performance substantially ! Needs full physics simulation before concluding M. Deveaux

  24. Global design: How many MVD stations? Vacuum window e+ MVD 2 Target MVD 1 STS 2 STS 3 STS 1 e- 5 cm Sensor response simulation: J. Enders - HK 53.18 M. Domachowski - HK 57.5 24 M. Deveaux

  25. System integration – An MVD for CBM Aim for thickness of 0.3% X0 (=0.3 mm Si equivalent) How to fix the sensors? CBM-MAPS consume ~1W/cm² How to bias? How to evacuate heat? … …without material … in vacuum? M. Deveaux

  26. Integration concept of the MVD rout Beam hole CBM acceptance Outside acceptance Geometry of MVD-stations • Vacuum operation requires light and actively cooled device. • Use cooling support from diamond to move heat out of acceptance • Put heat sink and FEE outside acceptance

  27. Integration concept of the MVD Sensor Sensor Sensor Sensor Sensor Sensor Sensor Sensor Sensor Sensor Discri Discri Discri Discri Discri Discri Discri Discri Discri Discri MIMOSIS1B MIMOSIS1A MVD Prototype (mock up) T. Tischler 27 M. Deveaux

  28. Simulation: Material budget of a first MVD station Heat sink 300 µm Si equivalent T. Tischler Cable Support Sensor Conservative estimate close to 0.3% X0 Improve using FPC with aluminum

  29. Validation of the cooling concept Aim: Validate the cooling concept with TPG DT = ~10K T. Tischler 25 W / 16 cm² • Observation: • Temperature gradient on the station appears acceptable • A 150 µm CVD diamond support might be sufficient for station 1 • Diamond => liquid heat transport needs optimization Vacuum compatible cooling concept for 1W/cm² seems robust. 29

  30. Prototype: Beam test setup MVD Prototype Reference telescope T. Tischler • Ambitioned performances: • Up to 10 MIMOSA-26 running @10k frames/s, 3.5µm resolution. • Local DAQ based on HADES TRB - 1.6 Gbps data, scalable. • Actively cooled prototype (<0.3% X0) • Passively cooled telescope arms (0.05% X0) M. Deveaux

  31. Prototype: Beam test setup 2 MIMOSA-26 operated with …. the prototype readout electronics See C.Schrader, HK 41.5 See B. Milanovic, HK 41.6 M. Deveaux

  32. Summary • CMOS MAPS provide an unprecedented compromise between precision measurements and rate capability. • Their performances were massively improved within 10 years. • MAPS are considered for STAR, CBM, ILC, ALICE, eRHIC … => Industrial trends help: Expect further improvements • Integration concept for the CBM-Micro Vertex Detector: • Host MAPS on a vacuum compatible diamond cooling support • Readout with ultra thin flex print cables • Build local DAQ based on HADES TRB • Status: • Prototype under construction, beam test middle 2012 M. Deveaux

  33. Outlook: The story has just started SERNWIETE (mechanical demonstrator) A bended MIMOSA-26 in a foil Ideafrom R. De Oliveira, W.Dulinski Thanks to the CBM-MVD collaboration: PICSEL group, sensor production AG Prof. Stroth, MVD integration radiation tolerance studies M. Deveaux

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