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CBM – Technical Challenges

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  1. CBM – Technical Challenges Walter F.J. Müller, GSI, Darmstadt for the CBM Collaboration

  2. Observables → Detector Requirements Capabilities Observables Momentum measurement Hadron ID Lepton ID: e or μ Photon detection Vertex reconstruction event-by-event fluctuations flow excitation function strangeness production: K, L, S, X, W low-mass vector mesons: ρ,ω,f hidden charm: J/Ψ Capacities High track density → highly granular detectors Large integrated luminosity high interaction rates (10 MHz) →fast detectors (100 kHz/ch) → efficient event selection several month/year beam → radiation hard detectors open charm: D0, D±,Ds CCNU Wuhan, November 2006

  3. CBM Setup Capabilities Momentum measurement Hadron ID Lepton ID: e or μ Photon detection Vertex reconstruction Capacities High track density → highly granular detectors Large integrated luminosity high interaction rates (10 MHz) →fast detectors (100 kHz/ch) → efficient event selection several month/year beam → radiation hard detectors CCNU Wuhan, November 2006

  4. [W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745] SIS100/ 300 Driving Factor 1: Rare Probes D → 106 int/sec J/Ψ→ 107 int/sec Integrated Luminosity: ~ 1014 int/lifetime for some sub-systems CCNU Wuhan, November 2006

  5. High Multiplicity Central Au+Au collision at 25 AGeV: URQMD + GEANT 160 p 170 n 360 -330 +360 0 41 K+ 13 K-42 K0 CCNU Wuhan, November 2006

  6. Driving Factor 2: Hit Densities For Au + Au @ 25 A GeV central collisions: at Vertex Detector at end of STS at ToF Wall horz. planevert. plane up to 1 hit/mm2/evt 10-2 hit/cm2/evt up to 1 hit/cm2/evt x 1014 int/life → ~ 2.5 MRad replace Vertex Detectorafter one run ~ 25 KHz/cm2/sec CCNU Wuhan, November 2006

  7. CBM Event Selection Requirements assume archive rate: few GB/sec 20 kevents/sec • In-medium modifications of hadrons onset of chiral symmetry restoration at high ρBmeasure: , ,   e+e- or μ+μ - open charm (D0, D±) • Strangeness in matter enhanced strangeness productionmeasure: K, , , ,  • Indications for deconfinement at high ρB anomalous charmonium suppression ?measure: D0, D±- J/  e+eor μ+μ - • Critical point event-by-event fluctuations measure: π, K offline trigger trigger ondisplaced vertex offline drives FEE/DAQarchitecture trigger trigger trigger on high pte+e- or μ+μ- pair offline CCNU Wuhan, November 2006

  8. Driving Factor 3: Tracking Trigger • Example: D0  K-+ (3.9%; c = 124.4 m) • reconstruct tracks • find primary vertex • find displaced tracks • find secondary vertex target few 100 μm 5 cm • high selectivity because combinatorics is reduced first two planesof vertex detector CCNU Wuhan, November 2006

  9. DAQ – Event Selection • Challenge: • no conventional first level trigger • first decision level requires tracking and vertexing • hard to do in a limited decision time • straight forward to use farming to achieve throughput • Solution: • build a system that is throughput limited, not latency limited • use self-triggered front-ends CCNU Wuhan, November 2006

  10. Buffer L1 Select L2 Select DAQ – Data Push Architecture Detector Self-triggered front-end Autonomous hit detection time distribution FEE No dedicated trigger connectivity All detectors can contribute to L1 Cave Shack Highbandwidth DAQ Large buffer depth available System is throughput-limitedand not latency-limited Some Programmable Logicand mostly CPU's Use term: Event Selection Archive CCNU Wuhan, November 2006

  11. Front-End for Data Push Architecture • Each channel detects autonomously all hits • An absolute time stamp, precise to a fraction of the sampling period, is associated with each hit • All hits are shipped to the next layer (usually concentrators) • Association of hits with events done later using time correlation • Typical Parameters: • with few 1% occupancy and 107 interaction rate: • some 100 kHz channel hit rate • few MByte/sec per channel • whole CBM detector: 1 Tbyte/sec CCNU Wuhan, November 2006

  12. Vertex Detector • Challenge: • ~30 x 30 μm pixel size • cope with 1 Mhz interaction rate • stand at least 1012 interactions • low material budget (0.2-0.3 % X0) • Solutions: • Active pixel sensors (MAPS) • DEPFET sensors CCNU Wuhan, November 2006

  13. 1st Draft Vertex Detector – MAPS Development • Base technology like STAR Heavy Flavor Tracker (HFT) • Working on: • faster readout: • column-parallel read-out • short columns • 10 MHz pixel rate @ 1 mW/column • radiation hardness • 1 MRad and 2x1012 neq/cm2 demonstrated so far • low mass support structure M. Winter, IPHC, StrasbourgJ. Stroth, Uni. Frankfurt CCNU Wuhan, November 2006

  14. Silicon Tracker • Challenges: • Sensor • radiation hard (must stand 1014 interactions) • 50 μm pitch, double sided, ~150 stereo, ladderable • Read-out • self-triggered, 128 ch, radiation tolerant • Support Structure • low mass • likely need cooled sensors CCNU Wuhan, November 2006

  15. Silicon Tracker – FEE Development • Start with N-XYTER chip from DETNI Collaboration • 128 channels, self-triggered (designed for neutron detectors !) • 2 ns time stamp accuracy • 32 Mhit/sec readout bandwidth • will be used in 2007/2008 prototyping • Next steps • lower power; fully digital interface • radiation hardness • Strategy • use same architecture also for read-out of highly granular gas detectors (e.g. GEM) → variants with adapted preamps CCNU Wuhan, November 2006

  16. N-XYTER Architecture Front-end targeted for Silicon strip (pos & neg) GEM's and MSGC's S. Buzzetti, Uni HeidelbergDETNI Coll. CCNU Wuhan, November 2006

  17. Fast Gas Tracking Detectors Needed in many places e+-e- setup μ+-μ- setup doinghadronic observables MUCH detector CCNU Wuhan, November 2006

  18. Fast Gas Tracking Detectors • Challenges: • hit density: 10-2 up to 1 hit/cm2 • hit rate: 25 kHz up to 2.5 MHz/cm2 • fluence: 1012 up to 1014 part/cm2 (~ 1 C/cm2) • Solution: • up to a few 100 kHz/cm2: (TRD or intermediate Tracker) • high-rate MWPC'sseveral 100 m2 needed for TRD or intermediate trackersignificant R&D done in the last years • above a few 100 kHz/cm2: (parts of Muon system) • GEM, Mircomegasrequirements depending on detailed MUCH layoutwork just starting within CBM CCNU Wuhan, November 2006

  19. Time-of-Flight Wall • Challenges: • Size: 150 m2 • hit density: 10-2 hit/cm2 • hit rate: 25 kHz/cm2 • System time resolution <= 80 ps • Solution: • Multigap RPC Counters with 'low' resistivity electrodes CCNU Wuhan, November 2006

  20. RPC Development • Example: Ceramic electrodes • controlled resistivity alumina109Ω cm at room temperature • efficiency drop • 9% /100 kHz in single gap • 2% @ 200 kHz for 4 gaps • Also under investigation: • warm glass • semiconductive glass • Outlook: • 25 kHz/cm2 rate is achievable • challenge is to control ageing Single gap P. Fonte, LIP, Coimbra For  pairsexpect ~60 ps for MIPS CCNU Wuhan, November 2006

  21. Summary • Hit rates and densities seem feasible • Main challenge is • control radiation damage / ageing • → long-term and comprehensive testing • system integration • → build complete sub-system prototypes CCNU Wuhan, November 2006

  22. CBM collaboration India (cont): Univ. Varanasi IIT Kharagpur Korea: Korea Univ. Seoul Pusan National Univ. Norway: Univ. Bergen Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Kaiserslautern Univ. Mannheim Univ. Münster FZ Rossendorf GSI Darmstadt Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Nucl. Phys. Inst. Krakow Croatia: RBI, Zagreb China: CCNU, Wuhan USTC, Hefei Cyprus: Nikosia Univ. Czech Republic: CAS, Rez Techn. Univ. Prague France: IReS Strasbourg Hungaria: KFKI Budapest Eötvös Univ. Budapest India: VECC Kolkata IOP Bhubaneswar Univ. Chandighar Portugal: LIP Coimbra Romania: NIPNE Bucharest Russia: IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg Kurchatov Inst., Moscow LHE, JINR Dubna LPP, JINR Dubna LIT, JINR Dubna MEPHI Moscow Obninsk State Univ. PNPI Gatchina SINP, Moscow State Univ. St. Petersburg Polytec. U. Ukraine: Shevshenko Univ. , Kiev CCNU Wuhan, November 2006

  23. The End Thanks for your attention CCNU Wuhan, November 2006

  24. The End Spares CCNU Wuhan, November 2006

  25. Especially instrumenteddetectors Trigger Primitives Dedicatedconnections Buffer Cave Limitedcapacity Shack L1 Accept Modestbandwidth L1 Trigger LimitedL1 triggerlatency Specializedtriggerhardware Standardhardware Conventional FEE-DAQ-Trigger Layout Detector fbunch FEE DAQ L2 Trigger Archive CCNU Wuhan, November 2006

  26. Fast Gas Detector Development • MWPC Example: Double-sided pad plane HCRTRD chamber for TRD • 3mm max. drift; 12 mm Xe • stable up to 200 kHz/cm2 • π rejection of >100 can be achieved with 6 layers and foil radiator M. Petrovici, NIPNE, Bucharest CCNU Wuhan, November 2006

  27. 4 2 3 1 Anode segment 2 Anode segment 1 Anode segment 3 Straw Detector with Segmented Anode Glass joint with 2 anode wiresand a read-out wire Feed-Through Joint plus spacer unit V Peshekhonov, JINR, Dubna CCNU Wuhan, November 2006