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Description of BTeV detector

DPF 2000 Aug 9 - 12 , 2000 Columbus, Ohio. Description of BTeV detector. Jianchun Wang Syracuse University Representing The BTeV Collaboration. Introduction. BTeV: dedicated beauty and charm experiment at pp collider at Fermilab

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Description of BTeV detector

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  1. DPF 2000 Aug 9 - 12 , 2000 Columbus, Ohio Description of BTeV detector Jianchun Wang Syracuse University Representing The BTeV Collaboration

  2. Introduction • BTeV: dedicated beauty and charm experiment at pp collider at Fermilab • Physics goal: mixing, CP violation, rare decays of b- and c- hadrons • Accurately determine Standard Model parameters • Search for physics beyond Standard Model Jianchun (JC) Wang

  3. Characteristics of b Production at Tevatron Jianchun (JC) Wang

  4. b production peaks at large angles with large bb correlation b production angle b production angle A Forward Detector at pp Collider BTeV detector covers forward region, 10-300 mrad The higher momentum b are at larger  bg Pseudo-rapidity  Jianchun (JC) Wang

  5. Main Challenges • High background ( sb/stot ~ 1/500 ), large data rate ( 1kHz ) to be recorded • Detached vertex trigger and background rejection • Deadtimeless trigger and DAQ system • Background from real b event can overwhelm “rare” processes  Excellent particle identification • Radiation hard detector components Jianchun (JC) Wang

  6. C0 collision Hall ( 9 m x 24 m ) The C0 Interaction Region C0 Assembly Building Jianchun (JC) Wang

  7. The BTeV Detector Pixel Vertex Detector Dipole Magnet Magnet Coil Beam Pipe Forward tracking RICH PbWO4 EM calorimeter Muon Toroid Jianchun (JC) Wang

  8. The Pixel Detector • Function: • Deliver clean, precise space points to detached vertex trigger • Provide vertex information for offline analysis • Pixel sensor • Eliminate ambiguity problems with high track density (essential to the detached vertex trigger) • Radiation hard, low noise • Easy pattern recognition • Pixels size: 50mm  400 mm (total 3  107 channels) 5mm Elevation View 10 of 31 Doublet stations Jianchun (JC) Wang

  9. Silicon Pixel Detector • FPIX2 Readout Chip • 3-bit analog readout • Noise ~ 100 e • 0.25mm CMOS process Pixel sensor Size: 50400 mm2 Thickness: 250 mm Type: n+np+ Jianchun (JC) Wang

  10. Support and Cooling • Carbon composite structures include integrated cooling tubes ( by ESLI) • Shingled surface, allow the multichip assemblies to overlap • Movable structure, adjustable distance between the sensor and the beam • Light mass material ( ~ 0.9 % X0 includes the detector) Jianchun (JC) Wang

  11. Pixel Test Beam Results • 280 mm thick detector bump bonded to custom made electronics chip developed at Fermilab • Excellent resolution ( requirement: 9 mm ) • Diamond target test, track density higher than BTeV Jianchun (JC) Wang

  12. Bp+p- PB distribution sL (cm) Decay length error pB (GeV) Decay Time Resolution • Decay length (from primary vertex to secondary vertex) <L> = gbctB = 480 mm  pB/mB(2700 mm at pB = 30 GeV) • Excellent resolution (sL 75 mm at pB = 30 GeV) • Reduces background • Allows detached vertex trigger • Smallest error near peak (30GeV) Jianchun (JC) Wang

  13. State efficiency(%) State efficiency(%) B p+p- 63 Bo K+p- 63 Bs DsK 71 Bo J/y Ks 50 B- DoK- 70 Bs J/yK* 68 B- Ksp- 27 Bo ropo 56 Detached Vertex Trigger • Idea: finds the primary vertex, selects events that have additional tracks miss it • Requirement: at least 2 tracks detached by more than 6s 1% minimum bias • Efficiency:(after the other analyses cuts) Jianchun (JC) Wang

  14. Forward Tracking System • Major functions: • Improve P measurement combined with pixel system • Reconstruct and measure all parameters for tracks outside the acceptance of pixel system • Project tracks into downstream detectors • Provide information for level 2 trigger • Combination of straw-tube chambers and silicon strips(along the beam line, 7 station per arm) • Straw-tube (4mm diameter, sx ~ 150 mm): small cell for large chamber, no heavy frame near the beam • Silicon strip (100mm pitch, sx ~ 29 mm): near the beam, handle high track density • Momentum resolution ( 0.4% - 0.9% ) Jianchun (JC) Wang

  15. Ring Imaging CHerenkov • Goal: p/K/p separation from 3 - 70 GeV/c • Radiators: freon, aerogel (~ 4cm thick) • Photon detector: hybrid photodiodes (HPD) Jianchun (JC) Wang

  16. Hybrid Photo Diode g • Electrostatic acceleration and focusing of a photo-electron on a silicon diode • Large active area ( ~ 80%), hexagonal close packed, no lens system needed • 163 channels, manufactured by DEP • Large HV (20kV) but no current draw window with a photo-cathode at -20 kV e Silicon diode Pins to readout chip Jianchun (JC) Wang

  17. Particle Identification Rings from Bop+p- High efficiency with excellent rejection Jianchun (JC) Wang

  18. The PbWO4 EM Calorimeter • Goal: • Reconstruction of g/p (B, etc), identification of electron • Excellent resolution, radiation hard • PbWO4 crystal • Radiation hard • Scintillation is fast, 99% of light emitted < 100 ns • Lateral size: 25.425.4 mm2 (front), 2626 mm2 (back) • Length 22 cm (25 X0) • Photo-multiplier tube (PMT) readout (no magnetic field) • Projective geometry, covers up to 210 mrad (reduce cost) • Total of 2  11,850 crystals needed Jianchun (JC) Wang

  19. p0 at 10 GeV BK*g s = 0.77% sM=2.6MeV Mgg(GeV) DE / Eg Expected Resolution Excellent Resolution: Jianchun (JC) Wang

  20. Expected Efficiency • High rate at small radius resolution and efficiency degrade • About 80% efficiency at large radius BK*g Jianchun (JC) Wang

  21. The Muon Detector • Goals: • Muon Identification • Trigger on di-muons in level 1, Provides a method of checking detached vertex triggering efficiency • Design: Two Toroids with three sets of position detectors • Toroid: 1 m thick, 1.5 Tesla, absorb hadron, deflect track • position detectors: 1 between toroids, two downstream B  B  To beam center Jianchun (JC) Wang

  22. r u v The Muon Position Detector • Planks of 3/8" diameter stainless steel proportional tubes • Eight overlapping pie shaped octants • Four views (r, u, v, r) • sp / p= 19%  0.6%  p Jianchun (JC) Wang

  23. DAQ Scheme See Paul Lebrun’s talk 7.6MHz crossing rate 2 - 4 kHz 40 KB/event Jianchun (JC) Wang

  24. The Status of BTeV • BTeV submitted a preliminary technical design report in May of 1999 and a full proposal in May of 2000 • BTeV is an approved experiment, Fermilab E897 • More information can be found at http://www-btev.fnal.gov Jianchun (JC) Wang

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