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

2. DPF 2000Jianchun (JC) Wang2 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

3. DPF 2000Jianchun (JC) Wang3 Characteristics of b Production at Tevatron

4. DPF 2000Jianchun (JC) Wang4 A Forward Detector at pp Collider The higher momentum b are at larger  b production angle b production peaks at large angles with large bb correlation  Pseudo-rapidity  BTeV detector covers forward region, 10-300 mrad

5. DPF 2000Jianchun (JC) Wang5  High background (  b /  tot ~ 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 Main Challenges

6. DPF 2000Jianchun (JC) Wang6 The C0 Interaction Region C0 collision Hall ( 9 m x 24 m ) C0 Assembly Building

7. DPF 2000Jianchun (JC) Wang7 The BTeV Detector Pixel Vertex Detector Dipole Magnet Magnet Coil Beam Pipe Forward tracking RICH PbWO 4 EM calorimeter Muon Toroid

8. DPF 2000Jianchun (JC) Wang8 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: 50  m  400  m (total 3  10 7 channels) Elevation View 10 of 31 Doublet stations 5mm

9. DPF 2000Jianchun (JC) Wang9 Silicon Pixel Detector FPIX2 Readout Chip  3-bit analog readout  Noise ~ 100 e  0.25  m CMOS process Pixel sensor Size: 50  400  m 2 Thickness: 250  m Type: n + np +

10. DPF 2000Jianchun (JC) Wang10 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 % X 0 includes the detector)

11. DPF 2000Jianchun (JC) Wang11 Pixel Test Beam Results  280  m thick detector bump bonded to custom made electronics chip developed at Fermilab  Excellent resolution ( requirement: 9  m )  Diamond target test, track density higher than BTeV

12. DPF 2000Jianchun (JC) Wang12 Decay Time Resolution Decay length (from primary vertex to secondary vertex) =  c    = 480  m  p B /m B (2700  m at p B = 30 GeV) Excellent resolution (  L  75  m at p B = 30 GeV) –Reduces background –Allows detached vertex trigger Smallest error near peak (30GeV) p B (GeV)  L (cm) B      P B distribution Decay length error

13. DPF 2000Jianchun (JC) Wang13 Detached Vertex Trigger State efficiency(%) State efficiency(%) B   +  - 63 B o  K +  - 63 B s  D s K 71 B o  J/  K s 50 B -  D o K - 70 B s  J/  K * 68 B -  K s  - 27 B o    o  o   Idea: finds the primary vertex, selects events that have additional tracks miss it  Requirement: at least 2 tracks detached by more than 6   1% minimum bias  Efficiency: (after the other analyses cuts)

14. DPF 2000Jianchun (JC) Wang14 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,  x ~ 150  m): small cell for large chamber, no heavy frame near the beam  Silicon strip (100  m pitch,  x ~ 29  m): near the beam, handle high track density  Momentum resolution ( 0.4% - 0.9% )

15. DPF 2000Jianchun (JC) Wang15 Ring Imaging CHerenkov  Goal:  /K/p separation from 3 - 70 GeV/c  Radiators: freon, aerogel (~ 4cm thick)  Photon detector: hybrid photodiodes (HPD)

16. DPF 2000Jianchun (JC) Wang16 Hybrid Photo Diode  e Silicon diode Pins to readout chip window with a photo-cathode at -20 kV  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

17. DPF 2000Jianchun (JC) Wang17 Particle Identification Rings from B o  +  - High efficiency with excellent rejection

18. DPF 2000Jianchun (JC) Wang18 The PbWO 4 EM Calorimeter  Goal:  Reconstruction of  (B , etc), identification of electron  Excellent resolution, radiation hard  PbWO 4 crystal  Radiation hard  Scintillation is fast, 99% of light emitted < 100 ns  Lateral size: 25.4  25.4 mm 2 (front), 26  26 mm 2 (back)  Length 22 cm (25 X 0 )  Photo-multiplier tube (PMT) readout (no magnetic field)  Projective geometry, covers up to 210 mrad (reduce cost)  Total of 2  11,850 crystals needed

19. DPF 2000Jianchun (JC) Wang19 Expected Resolution M  (GeV)  0 at 10 GeV  M =2.6MeV  E / E   = 0.77% B  K*  Excellent Resolution:

20. DPF 2000Jianchun (JC) Wang20 Expected Efficiency High rate at small radius  resolution and efficiency degrade About 80% efficiency at large radius B  K* 

21. DPF 2000Jianchun (JC) Wang21 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 To beam center BB BB

22. DPF 2000Jianchun (JC) Wang22 The Muon Position Detector  Planks of 3/8" diameter stainless steel proportional tubes  Eight overlapping pie shaped octants  Four views (r, u, v, r)   p / p= 19%  0.6%  p r v u

23. DPF 2000Jianchun (JC) Wang23 DAQ Scheme See Paul Lebrun’s talk 7.6MHz crossing rate 2 - 4 kHz 40 KB/event

24. DPF 2000Jianchun (JC) Wang24 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