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Status of the Micro Vertex Detector

Status of the Micro Vertex Detector. M. Deveaux , Goethe University Frankfurt for the CBM-MVD collaboration. The CBM-MVD. We are here. CBM. How will it look. Silicon Tracking System. Magnet. Vacuum vessel. DAQ cards. MVD - planes. z. Target (Gold). Detector2. Detector 1.

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Status of the Micro Vertex Detector

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

  2. The CBM-MVD We are here CBM M. Deveaux

  3. How will it look Silicon Tracking System Magnet Vacuum vessel DAQ cards MVD - planes 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 Central Au + Au collision (25 AGeV) 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) • => Eventually: Detectors in vacuum • A good time resolution to distinguish • the individual collisions (few 10 µs) • Very good radiation tolerance • (>1013neq/cm²) M. Deveaux,

  5. Status of the sensors (last meeting 2011) • 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. A word on simulation MVD and STS integration M. Deveaux

  7. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 7 M. Deveaux

  8. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 8 M. Deveaux

  9. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 9 M. Deveaux

  10. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 10 M. Deveaux

  11. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 11 M. Deveaux

  12. Global design: How many MVD stations? Vacuum window MVD 2 Target MVD 1 STS 2 STS 3 STS 1 5 cm Tracking, artist view 12 M. Deveaux

  13. L1 “MVD track finding efficiency” vs. MVD design 90 4 MVD stations 3 MVD stations 2 MVD stations MVD track finding efficiency[%] C. Trageser 100% = primary tracks, geo- metrically accepted by MVD, > 4 hits in STS 50 10 pile up None 5 Tracking efficiency = 83% for standard MVD, drops to <55% at pile up 10 Tracking efficiency is substantially improved by additional stations Impact for 4th station to be studied in detail M. Deveaux

  14. Background rejection capabilities of the MVD Bad reconstruction Some bad hits 50 C. Trageser Good track finding Not accepted accepted BG-tracks / event Cuts: p >1 GeV pt>0.3 GeV Long (>4 in STS) IP<600µm IP/sIP>6 0 None 5 10 More than 2 MVD stations are needed for BG rejection Expect good sensitivity for open charm with >3 stations M. Deveaux

  15. Sensor R&D for (Int_t Mimosa=1; true; Mimosa++) { Build_Next_Prototype (Mimosa); Test_Prototype (Mimosa); Enjoy_Spectacular_Progress_Of(Mimosa); ImproveDesign(Mimosa);} M. Deveaux

  16. Long standing believes vs. technological progress A small pixel pitch is needed to reach the radiation tolerance needed for CBM CBM goal M. Deveaux

  17. 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

  18. 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++

  19. 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

  20. 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

  21. Long standing believes vs. technological progress A small pixel pitch is needed to reach the radiation tolerance needed for CBM D. Doering et al. – Mimosa18 AHR CBM goal MIMOSA-32: 20x40µm² pixel 99.5% M. Deveaux

  22. Status of the sensors (last meeting 2011) • 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

  23. Update on sensor R&D • 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

  24. Radiation tolerance of MAPS • So far - Radiation tolerance limited by: • Leakage current – noise • Conduction channels between transistors (?) • Known solution: • Use 0.18 µm CMOS instead of 0.35µm CMOS DONE Challenge: Find MAPS-compatible 0.18µm CMOS process First prototype: MIMOSA-32 • 32 different kinds of pixels • 32 µs readout time • 32 mm² surface 33 mm² M. Deveaux

  25. Long standing believes vs. technological progress A small pixel pitch is needed to reach the radiation tolerance needed for CBM Mimosa-32, 20x40µm² pitch (Beam test @ SPS by IPHC, preliminary) 99.5% detection efficiency After 1013neq/cm² + 1 MRad ! CBM goal MIMOSA-32: 20x40µm² pixel 99.5% M. Deveaux

  26. Long standing believes vs. technological progress A small pixel pitch is needed to reach the radiation tolerance needed for CBM Mimosa-32, 20x40µm² pitch (Beam test @ SPS by IPHC, preliminary) 99.5% detection efficiency After 1013neq/cm² + 1 MRad ! CBM goal MIMOSA-32: 20x40µm² pixel 99.5% M. Deveaux

  27. Why is this important? 20x20µm² 20x40µm² Pixel withpedestalcorrection ~2000 ~1000 discriminators 12 µs/frame 50 µs/frame 25 µs/frame On - chip cluster-finding processor Output: Cluster information (zerosuppressed) Requires 0.18µm CMOS Test chip submitted M. Deveaux

  28. Why is this important MAPS are too slow for CBM 20x20µm² 20x40µm² Pixel withpedestalcorrection ~2000 ~1000 discriminators 12 µs/frame 50 µs/frame 25 µs/frame On - chip cluster-finding processor Output: Cluster information (zerosuppressed) Requires 0.18µm CMOS Test chip submitted M. Deveaux

  29. Why is this important There is a clear strategy for reaching the readout speed needed for CBM 20x20µm² 20x40µm² Pixel withpedestalcorrection ~2000 ~1000 discriminators 12 µs/frame 50 µs/frame 25 µs/frame On - chip cluster-finding processor Output: Cluster information (zerosuppressed) Requires 0.18µm CMOS Test chip submitted M. Deveaux

  30. Update on sensor R&D • 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

  31. MIMOSA-32 and ionizing radiation Sensor irradiated with X-rays @ CERN D. Doering Noise Noise increases much slower (as expected) Higher initial noise (not expected) M. Deveaux

  32. Sensor R&D: Tolerance to non-ionising radiation +3.3V Output Study noise with varied size of transistor gate +3.3V GND SiO2 SiO2 GND SiO2 SiO2 N+ P++ P++ N++ P++

  33. Comparison with 0.18µm vs. AMS 0.35 0.35 µm, big 0.18µm, small 0.18µm, tiny D. Doering M. Deveaux

  34. Going into details M. Winter et al.

  35. Random Telegraph Signal M. Winter et al. Sensors see difference between two samples Side peaks due to change of state. Problem understood, => Need bigger gates RTS, illustration

  36. So what? Mimosa-32, 20x20µm² pitch (Beam test @ SPS by IPHC, preliminary) 99.5% det. efficiency (S/N ~30) After 3 MRad at +15°C! Optimized for one parameter Current compromise M. Deveaux

  37. So what? Mimosa-32, 20x20µm² pitch (Beam test @ SPS by IPHC, preliminary) 99.5% det. efficiency (S/N ~30) After 3 MRad at +15°C! Optimized for one parameter Current compromise M. Deveaux

  38. Next steps in the R&D Already excellent but Get rid of RTS 4 prototypes submitted Pixel withpedestalcorrection ~1000 discriminators Prototype MIMOSA-22THR submitted On - chip cluster-finding processor Prototype SUZE - 2 submitted Output: Cluster information (zerosuppressed) First prototypes in 0.18µm CMOS show spectacular results. Full engineering run (11 CBM relevant prototypes) submitted. More to come => Stay tuned. M. Deveaux

  39. How to integrate the sensors? MIMOSA-26 (600 kPixel, 104 frames/s, zero suppression) Thinned to 50µm, at IKF Frankfurt See next talk (M. Koziel) M. Deveaux, CBM Collaboration Meeting, Kolkata, 24-28. Sept 2012

  40. Summary • Simulation • MVD needs 3 or 4 stations for good performance • Sensors for MVD (since 2010) • Radiation tolerance (non-io.) was improved by factor 10 • Radiation tolerance (io) was improved by factor > 3 • All sensor requirements for CBM are individually demonstrated • Still room for improvement in 0.18µm process • Ongoing effort to combine all functionalities Prototype and integration: Very promising (see next talk)

  41. Thanks to: S. Amar-Youcef, B. Milanovic, Q. Li (Prototype firmware and analysis) M. Koziel, T.Tischler (mechanical integration) B. Neumann (JTAG slow control), M. Wiebusch (analog electronics) C. Schrader (DAQ concept and coordination, now with BOSCH), C. Trageser (simulation) PICSEL Group IPHC, Strasbourg (sensor R&D + test) The prototype DAQ at night M. Deveaux, CBM Collaboration Meeting, Kolcata, 24-28. Sept 2012

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