Status of the Silicon Tracking System

1. Status of the Silicon Tracking System Johann M. Heuser, CBM Collaboration Meeting, GSI, 28.2.2008 • News and update on • Layout studies, realistic detector response • Radiation environment • Prototyping of detectors and components • R&D Cooperations, Tasks J.M. Heuser − Status of the Silicon Tracking System

2. STS detector layout 8 stations double-sided silicon micro-strip detectors, thickness 300mm Building block is a low-mass ladder structure Support made of carbon boxes Cables represented as capton boxes, thickness 200mm Readout electronics: thick layers of silicon and aluminium J.M. Heuser − Status of the Silicon Tracking System

3. Station layout Sectors: 6cm wide, 2 - 18 cm high Station 1 (R. Karabowicz) Station 8 About 1.2 million channels total.Occupancy reaches 5.7% in central Au+Au collisions at 25 AGeV. J.M. Heuser − Status of the Silicon Tracking System

4. Tracking results (R. Karabowicz) OLD SETUP WITH ADDITIONAL MATERIAL tracking eff. 93.8 % mom. resol. 1.7 % NEW SETUP WITHOUT ADDITIONAL MATERIAL tracking eff. 90.3 % mom. resol. 1.6 % OLD SETUP WITHOUT ADDITIONAL MATERIAL NEW SETUP WITH ADDITIONAL MATERIAL tracking eff. 87.9 % mom. resol. 1.6 % tracking eff. 96.18 % mom. resol. 1.3 % J.M. Heuser − Status of the Silicon Tracking System

5. Realistic detector response (I) Simple Event Display so far: single strips underneath Geant hits activated now: charge chared by several strips (R. Karabowicz) Size of plot [cm] Position in STS: X Y Z Sector view: Front strips in blue Back strips in green MC points in circles Reconstructed hits: stars Front strips’ ADC distribution Back strips’ ADC distribution J.M. Heuser − Status of the Silicon Tracking System

6. Realistic detector response (II) Problem: wide, overlapping clusters in the most upstream stations To be answered: Do we require pixel detectors in the first STS stations? J.M. Heuser − Status of the Silicon Tracking System

7. Tracking results - incl. clustering Clustering included tracking eff. 74.5 % mom. resol. 1.6 % Work in progress: DIGITIZER: TOO SIMPLE HIT FINDER: TOO SIMPLE Station 1 Station 8 (R. Karabowicz) J.M. Heuser − Status of the Silicon Tracking System

8. Radiation environment iFluka framework (D. Bertini) 1-MeV neutron equivalent fluences in CBM cave DPM (beam dump) UrQmd (interaction in target) J.M. Heuser − Status of the Silicon Tracking System

9. Radiation assessment in CBM (I) per min. bias UrQMD event, 25 AGeV (D. Bertini) J.M. Heuser − Status of the Silicon Tracking System

10. Radiation assessment in CBM (II) MDV+STS Scoring planes MUCH scoring planes J.M. Heuser − Status of the Silicon Tracking System

11. Neutron fluence in STS STS 5 STS 6 min. bias UrQMD @ 25 AGeV back scattering from MUCH absorber STS 7 STS 8 ~ 1 nequiv. per min. bias interaction Dose in 6 years of CBM running: ~ 3  1014 nequiv. Very Significant !! (D. Bertini) J.M. Heuser − Status of the Silicon Tracking System

12. Ionizing dose Station 1, z =30cm Calculated with GEANT for 6 years* of CBM running. *1 year = 2 months at 107 int/s (R. Karabowicz) comparable result with FLUKA Station 8, z =100cm Station 4, z =50cm J.M. Heuser − Status of the Silicon Tracking System

13. STS built from single-sided strip detectors • Why to study • Technology "radiation hard" • May be easier to construct a b a • Geometry composed of 28 stations • First station has vertical strips • Second station has stereo strips • 0.5 cm distance between stations. • Digitizer developed • Ideal hit finder combining strips belonging to one track. • Modified L1 tracking b First trials: (R. Karabowicz) (I. Kisel) Tracking efficiency ~ 80 % no advanced features included (e.g. no computing speed optimization) J.M. Heuser − Status of the Silicon Tracking System

14. Microstrip detector prototype CBM01, 8/2007 Test sensors 4" wafer, 285 µm Si Double-sided, single-metal, 256256 strips, orthogonal, 50(80) µm pitch, size: 1414 (22 22)mm2 CBM01B1 CBM01B2 Main sensor Double-sided, double-metal, 1024 strips per side, 50 µm pitch, 15º stereo angle, full-area sensitive, contacts at top + bottom edge, size: 5656 mm2 CBM01 Designed to explore CBM-specific connectivity J.M. Heuser − Status of the Silicon Tracking System

15. Towards 2nd design iteration CIS activity in frame of german BMWI project INNOWAT -“SPID“ L. Long and R. Rolf, CIS Test wafer to explore primarilyradiation tolerance Full detectors 7 pixel detectors; 18 strip detectors. Test structures: 3 Pad diodes, 4 Gate diodes, 6 PDTF, 2 SIMS, 2 SDM. poly silicon bias structures Process status 2/2008: First active implant finished. J.M. Heuser − Status of the Silicon Tracking System

16. 1/C2 [pF-2] I [µA] I [µA] U [V] U [V] U[V] Characterization of CBM01 at CIS • IV and CV characterization of CBM01B1, CBM01B2, CBM02 (W. John et al.) • reported at CBM Meeting September 2007 J.M. Heuser − Status of the Silicon Tracking System

17. Find application in various activities of beginning detector module R&D Only currently available CBM-specific microstrip detectors. Very important for STS prototyping!! GSI: Test board (CBM01B2, preparation, report A. Lymanets) Test beam tracking module (planned) KINR Kiev: Pre-prototype module & CBM01B1 detector tests (electrical, diode laser, radioactive source) (report V. Pugatch) Kharkov/JINR: Test board with microcable fanout structure (planned) Cracow: n-XYTER-SUCIMA board with CBM01B2 (planned) + many new ideas around J.M. Heuser − Status of the Silicon Tracking System

18. Detector test board, GSI produced 2/2008 • test global detector characteristics • e.g. IV, CV • access both detector sides • contact a few strips for detailed measurements, including n-XYTER readout • do all this as quickly and as simple as possible to start work (A. Lymanets, J. Heuser) J.M. Heuser − Status of the Silicon Tracking System

19. Detector module pre-prototypes, KINR Kiev (V. Pugatch) CBM01-B1 detector: p-side on test board CBM01 detector, chip cable on carbon fibre support J.M. Heuser − Status of the Silicon Tracking System

20. I [µA] EStrip U [V] E Strip+1 CBM01 – first measurements at KINR Charge collection near surface Current-Voltage behaviour CBM01-B1 226 Ra from p-side, p-strips 5@6 EStrip Mapping of inter-strip charge charing with laser positioning system (V. Pugatch) µm J.M. Heuser − Status of the Silicon Tracking System HV = 50 V HV = 70 V

21. 14 µm Al on 10 µm Kapton 55 cm long, 1024 lines, 100 µm pitch Readout cables, SE SRTIIE Kharkov (V. Borshchov et al.) 1024 strips50 µm pitch2 cm long first pre-prototypes produced Analog readout cable. J.M. Heuser − Status of the Silicon Tracking System

22. R&D cooperations, tasks ISTC project: “CBM Silicon Tracker“ (GSI, KRI St. Petersburg, MSU Moscow, IPHC Strasbourg) HadronPhysics2 I3 JRA: 9/2007Proposal: “Ultra-thin silicon tracking and vertex detection systems“ ... decision in 2008 ... CBM STS Consortium: 2008 - 2010 JINR-SINP-KRI-SPbSU-SESRITIIE-BTI-(IHEP)-GSI Finnland:FAIR member, in-kind contribution to CBM "single-sided rad-hard microstrip detectors" project under preparation To build and test a prototype(s) of the CBM STS Ladder GSI R&D cooperations: GSI-Kiev Inst. for Nucl. Research J.M. Heuser − Status of the Silicon Tracking System

23. Summary • STS still in conceptual design phase. • Progress with essential details, missing so far, is being made, including: • Realistic detector response (signal sharing, clusters) • Hit densities: - Strip technology in most upstream stations? - Are pixel detectors required? • Radiation study: How harsh are the operation conditions? • Deep consequences for the detector technologies and operating scenario. • Explore technologies: Double/single-sided strip detectors, AC/DC coupling... • Detector module concept: Very challenging design in mind, motivated by the low-mass requirement of our physics. Doable? • Risk management: Identify potential failures, redundant approaches, conservative and aggressive technical solutions. • Detector R&D: Essential. Becomes lively! Teams are forming. Preparations of test systems, test beams! • To aid this: Latest insights/results will be compiled in a technical document. J.M. Heuser − Status of the Silicon Tracking System