1 J.M. Heuser − CBM Silicon Tracking System Development of a Silicon Tracking System for the CBM Experiment at FAIR Johann M. Heuser, GSI Darmstadt for the CBM Collaboration DPG-Tagung "Hadronen und Kerne", Gießen, 13. März 2007 The Compressed Baryonic Matter Experiment The Silicon Tracking System Performance Studies and Detector R&D

2 J.M. Heuser − CBM Silicon Tracking System GSI today FAIR 2015 CBM The Compressed Baryonic Matter Experiment: What are the properties of dense nuclear matter? SIS-300 CBM - expected in extreme objects: cores of neutron stars, certain supernovae Laboratory: collide nuclei of heavy elements PhysicsObservables In-medium modifications of hadrons: Onset of chiral symmetry restoration , ,   e + e - (μ + μ - ) open charm: D 0, D ± Indications for deconfinement: Anomalous charmonium suppression ? D 0, D ±, J/   e + e - (μ + μ - ) Strangeness in matter: Enhanced strangeness production K, , , ,  Critical point: Event-by-event fluctuations , K Challenge Precise track + momentum measurement Vertex reconstruction Particle identification Nuclear collisions Au beam, 25 AGeV, on Au target up to 10 MHz interaction rate up to 1000 particles/event rare probes phase diagram QCD SN 1054

3 J.M. Heuser − CBM Silicon Tracking System Concept of the CBM Experiment Electron-hadron setup Muon-(hadron) setup MVD + STS RICH TRDs ECAL TOF MVD + STS TRDs MUCH ECAL TOF

4 J.M. Heuser − CBM Silicon Tracking System Silicon Detector System MVD (Micro Vertex Detector) + STS (Silicon Tracking System) 1 T field

5 J.M. Heuser − CBM Silicon Tracking System Microstrip Tracking Stations material budget momentum resolution tracking efficiency - strip lengths - stereo angle - station segmentation strip vs. pixel stations r/o electronics sensors station 6 Microstrip detector module: Layout studies: 50 µm strip pitch 15º stereo angle ~20 – 50 cm double-sided sensors

6 J.M. Heuser − CBM Silicon Tracking System Challenge: Hit densities Detector occupancy 6 tracking stations ~ 5000 physical hits ~ 5000 physical hits per central event combinatorial hit challenge: ~ hits ~ hits 2 pixel, 4 strip stations: ~ hits 6 strip stations: ~ hits fraction of fired strips x [cm] y [cm] real hit strip hit station 5 station 5 z = 50cm

7 J.M. Heuser − CBM Silicon Tracking System STS Performance: Tracking Track reconstruction "Cellular Automaton + Kalman Filter" "CBMRoot " Momentum resolution ~ 1% 697 rec. tracks ~ 1% ghost tracks central collision Au beam, 25 AGeV, on Au target efficiency [%] momentum [GeV/c] pixels + strips: ± 0.09 only strips: ± 0.12 pixels +strips: ± 0.14 only strips: ± 0.15 Tracking efficiency primary tracksall rec. tracks

8 J.M. Heuser − CBM Silicon Tracking System STS+MVD Performance: Vertexing Measurement of the D 0 signalVertex resolution S/B 2  = 4.4 Eff = 3.25% D 0 → K -  + (c  = 124  m) = 4∙ MVD stations at z= cm ~54  m sec. vertex resolution Proton identification with TOF 1.6 ×10 7 central Au+Au collisions, 25 AGeV primary secondary

9 J.M. Heuser − CBM Silicon Tracking System Towards a Microstrip Detector Module Development goal & challenge: sensors, single or chained readout thin flex multi-line fine-pitch cables fast, self-triggered readout: - outside of STS aperture - capacity-matched, low noise low-mass mechanical support conceptional CAD study as a building block of the tracking stations  focus on "low mass" + fast "self-triggered" readout

10 J.M. Heuser − CBM Silicon Tracking System Microstrip Detector Development Two streams of activities: double-sided sensors, different technologies 1) Moscow State University, SiLab: ~300 µm, AC coupling, poly-silicon biasing, p-stops, 15 deg stereo angle connectivity: top/bottom + sides goal: study radiation tolerance 2) GSI together with CIS, Erfurt: ~300 µm, AC coupling, punch-through biasing, p-spray, 15 deg stereo angle, double-metal interconnections on p side goal: connectivity study for module construction; r/o at top/bottom edge n side: "vertical" strips p side: "stereo" strips p side: "stereo" strips with "double metal" blue: double metal connections of strips in regions I to III n side: "vertical" strips III r/o direction I II

11 J.M. Heuser − CBM Silicon Tracking System 256 x 256 strips 80 µm pitch 90 deg stereo angle 256 x 256 strips 50 µm pitch 90 deg stereo angle 1024 x 1024 strips 50 µm pitch 15 deg stereo angle 4" wafer, 280 µm thick Microstrip Detector R&D with CiS, Erfurt Sensor design: finished 12/2006. Delivery in Summer 2007: batch of ~ 20+ wafers. Plenty of sensors for a variety of tests of first sensor and detector concepts. sensor p side r/o chip sensor n side test systems sensor r/o chip interconnects concepts

12 J.M. Heuser − CBM Silicon Tracking System Microstrip r/o chip "N-XYTER" N-XYTER chip produced 2006; DETNI Consor- tium − GSI test system under construction micro- strip sensor N-XYTER chip Data Driven Front-End: Asynchronous Channel Trigger 128 channels 50.7 µm pitch dual polarity 30 ns peaking time ~1.4 ns jitter thresholds: > 2700 e count rates: ~160 kHz/strip token ring r/o scheme power: ~ 30 mW/ch (high!!!) 0.35  m CMOS ASIC evaluation + first sensor tests Next steps: N-XYTER r/o hybrid for full-size sensors Compatible with CBM DAQ board prototypes. Lab and beam tests! Future: new chip: CBM-XYTER

13 J.M. Heuser − CBM Silicon Tracking System Summary CBM: Baseline experiment at FAIR. Running in Very interesting physics program on the QCD phase diagram: "Properties of dense nuclear matter" Challenge: CBM is a 2nd generation, specialized experiment. Must measure: rare probes and fluctuations, correlations  high interaction rates, high track multiplicities Requires: High-performance Silicon Tracking System  efficient tracking, high momentum resolution, sec. vertexing Simulation studies: STS concept works. Detector R&D: Has started. Demonstrate technical feasibility.  Microstrip  FEE, DAQ  Mechanics, cables etc. sensors components for module prototyping Goal: Starting with small test systems, build and characterize a prototype tracking system in the next years.

14 J.M. Heuser − CBM Silicon Tracking System CBM Collaboration Russia: IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg China: CCNU Wuhan USTC Hefei Croatia: RBI, Zagreb Portugal: LIP Coimbra Romania: NIPNE Bucharest Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Nucl. Phys. Inst. Krakow LIT, JINR Dubna MEPHI Moscow Obninsk State Univ. PNPI Gatchina SINP, Moscow State Univ. St. Petersburg Polytec. U. Ukraine: Shevchenko Univ., Kiev Cyprus: Nikosia Univ. Univ. Mannheim Univ. Münster FZ Rossendorf GSI Darmstadt Czech Republic: CAS, Rez Techn. Univ. Prague France: IPHC Strasbourg Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Kaiserslautern Hungaria: KFKI Budapest Eötvös Univ. Budapest India: VECC Kolkata SAHA Kolkata IOP Bhubaneswar Univ. Chandigarh Univ. Varanasi IlT Kharagpur Korea: Korea Univ. Seoul Pusan National Univ. Norway: Univ. Bergen Kurchatov Inst. Moscow LHE, JINR Dubna LPP, JINR Dubna 46 institutions > 400 members Strasbourg, September 2006 CBM related talks: C. Höhne HK 31.4 M. Klein-Bösing HK 16.8T. Galatyuk HK 19.3 A. Kiseleva HK 19.4J. Heuser HK 22.2 K. Solvag HK 34.8E. Cordier HK 47.4 S. Gorbunov HK 53.1C. Steinle HK 53.4 Poster on CBM Micro Vertex Detector: C. Müntz HK 49.23

15 J.M. Heuser − CBM Silicon Tracking System Backup slides

16 J.M. Heuser − CBM Silicon Tracking System Stereo angle [deg] y-resolution [µm] eff. (primary tracks, %) efficiency (all tracks, %) momentum resolution,% ghost track rate, % STS Layout Studies material budget momentum resolution tracking efficiency - strip lengths - stereo angle - stereo angle - station segmentation strip vs. pixel stations r/o electronics sensors Microstrip detector module: Layout studies: 50 µm strip pitch 15º stereo angle ~20 – 50 cm double-sided sensors

17 J.M. Heuser − CBM Silicon Tracking System CBM01 design: focus on interconnectivity Layout of the bond pad pattern and the double-metal line connections of the corner strips. I II III r/o direction

18 J.M. Heuser − CBM Silicon Tracking System STS station fluence per min. bias event [particles/cm 2 ] fluence per CBM year [particles/cm 2 ] z=100 cm~ 0.25~ 1.25 × z= 30 cm~ 2.5~ 1.25 × [z= 10 cm][~ 25][~ 1.25 × ] The detector system would have to be operated for typically 3-4 years with one set of sensors. Interaction rate: 10 7 /s Effective CBM run year: 2 months at full operation 5 × 10 6 s Particle fluencies in the most exposed parts of the tracking stations: URQMD generator, Au+Au 25 GeV/nucleon, primary particles. More refined simulations are in progress that take into account also secondary particle production. STS requirement on radiation hardness radiation tolerance: > 5 × MeV n equiv. × 10 7 /s × 5×10 6 s

19 J.M. Heuser − CBM Silicon Tracking System Primary particle rates in STS stations for central Au+Au collisions at 25 GeV/nucleon. Factor central  min. bias: × ~ 1/4 Particle energy spectrum for min. bias Au+Au collisions at 25 GeV/nucleon.