1. Klaus Honscheid 1 Ohio State University BTeV – A Dedicated B Physics Experiment at the Tevatron Collider Klaus Honscheid The Ohio State University DPF 2002, May 24, 2001

2. Klaus Honscheid 2 Ohio State University BTeV Collaboration Belarussian State- D.Drobychev, A. Lobko, A. Lopatrik, R. Zouversky UC Davis - P. Yager Univ. of Colorado-J. Cumalat Fermi National Lab J. Appel, E. Barsotti, C. N. Brown, J. Butler, H. Cheung, G. Chiodini, D. Christian, S. Cihangir, R. Coluucia, I. Gaines, P. Garbincius, L. Garren, E. Gottschalk, A. Hahn, P. Kasper, P. Kasper, R. Kutschke, S. Kwan, P. Lebrun, P. McBride, M. Votava, M. Wang, J. Yarba Univ. of Florida at Gainesville P. Avery University of Houston M. Bukhari, K. Lau, B. W. Mayes, V. Rodriguez, S. Subramania Illinois Institute of Technology R. A. Burnstein, D. M. Kaplan, L. M. Lederman, H. A. Rubin, C. White Univ. of Illinois- M. Haney, D. Kim, M. Selen, J. Wiss Univ. of Insubria in Como- P. Ratcliffe, M. Rovere INFN - Frascati- M. Bertani, L. Benussi, S. Bianco, M. Caponero, F. Fabbri, F. Felli, M. Giardoni, A. La Monaca, E. Pace, M. Pallotta, A. Paolozzi INFN - Milano - G. Alimonti, P. D’Angelo, L. Edera, S. Magni, D. Menasce, L. Moroni, D. Pedrini, S.Sala, L. Uplegger INFN - Pavia - G. Boca, G. Liguori, & P. Torre INFN - Torino – R. Arcidiacono, S. Argiro, S. Bagnasco, N. Cartiglia, R. Cester, F. Marchetto, E. Menichetti, R. Mussa, N. Pastrone IHEP Protvino, Russia A. Derevschikov, Y. Goncharenko, V. Khodyrev, V. Kravtsov, A. Meschanin, V. Mochalov, D. Morozov, L. Nogach, K. Shestermanov, L. Soloviev, A. Uzunian, A. Vasiliev University of Iowa C. Newsom, & R. Braunger University of Minnesota V. V. Frolov, Y. Kubota, R. Poling, & A. Smith Nanjing Univ. (China) T. Y. Chen, D. Gao, S. Du, M. Qi, B. P. Zhang, Z. Xi Zhang, J. W. Zhao Ohio State University K. Honscheid, & H. Kagan Univ. of Pennsylvania W. Selove Univ. of Puerto Rico A. Lopez, & W. Xiong Univ. of Science & Tech. of China - G. Datao, L. Hao, Ge Jin, T. Yang, & X. Q. Yu Shandong Univ. (China) - C. F. Feng, Yu Fu, Mao He, J. Y. Li, L. Xue, N. Zhang, & X. Y. Zhang Southern Methodist University - T. Coan SUNY Albany - M. Alam Syracuse University M. Artuso, S. Blusk, C. Boulahouache, O. Dorjkhaidav, K. Khroustalev, R.Mountain, N. Raja, T. Skwarnicki, S. Stone, J. C. Wang Univ. of Tennessee T. Handler, R. Mitchell Vanderbilt University W. Johns, P. Sheldon, K. Stenson, E. Vaandering, & M. Webster Univ. of Virginia: M. Arenton, S. Conetti, B. Cox, A. Ledovskoy Wayne State University G. Bonvicini, & D. Cinabro, A. Shreiner University of Wisconsin M. Sheaff York University S. Menary

3. Klaus Honscheid 3 Ohio State University CKM, CP and all that Magnitudes Bd, Bs Mixing Phases From Hocker et al: Current constraints on bd CKM triangle From Peskin: Many independent checks are needed

4. Klaus Honscheid 4 Ohio State University Some crucial measurements

5. Klaus Honscheid 5 Ohio State University B Physics at Hadron Colliders The Opportunity –Lot’s of b’s (a few times 10 11 b-pairs per year at the Tevatron) –“Broadband, High Luminosity B Factory” (B d, B u, B s, b-baryon, and B c ) –Tevatron luminosity will increase to at least 5x10 32 –Cross sections at the LHC will be 5 times larger –Because you are colliding gluons, it is intrinsically asymmetric so time evolution studies are possible (and integrated asymmetries are nonzero) The Challenge –Lot’s of background (S/N 1:500 to 1:1000) –Complicated underlying event –No stringent kinematic constraints that one has at an e + e - machine –Multiple interactions These lead to questions about the triggering, tagging, and reconstruction efficiency and the background rejection that can be achieved at a hadron collider

6. Klaus Honscheid 6 Ohio State University The Tevatron as a b & c source Value Luminosity b cross-section # of b’s per 10 7 sec b fraction c cross-section Bunch Spacing Luminous region length Luminous region width Interactions/crossing 2 x 10 32 100  b 4 x 10 11 10 -3 >500  b 132 ns  z = 10-20 cm  x ~  y ~ 50  m property

7. Klaus Honscheid 7 Ohio State University b production angle Characteristics of hadronic b production The higher momentum b’s are at larger  ’s b production peaks at large angles with large bb correlation b production angle   BTeV Central Detectors Mean  ~0.75

8. Klaus Honscheid 8 Ohio State University A simulated BTeV Event

9. Klaus Honscheid 9 Ohio State University

10. Klaus Honscheid 10 Ohio State University The BTeV Spectrometer (revised) Single Arm Full Pixel Detector Full Trigger and DAQ Reduce costs New baseline cost ~M$100 Use extra bandwidth to loosen trigger Better lepton id Re-gain some performance New baseline performance about 70% of original two- arm spectrometer

11. Klaus Honscheid 11 Ohio State University Key Design Features of BTeV ¬A dipole magnet (1.6 T) and 2 1 spectrometer arms ­A precision vertex detector based on planar pixel arrays ®A detached vertex trigger at Level I ¯High resolution tracking system (straws and silicon strips) °Excellent particle identification based on a Ring Imaging Cerenkov counter.  A lead tungstate electromagnetic calorimeter for photon and  0 reconstruction ²Excellent identification of muons  A very high capacity data acquisition system which frees us from making excessively specific choices at the trigger level

12. Klaus Honscheid 12 Ohio State University Pixel Vertex Detector Reasons for Pixel Detector: Superior signal to noise Excellent spatial resolution -- 5-10 microns depending on angle, etc Very low occupancy Very fast Radiation hard Special features: It is used directly in the L1 trigger Pulse height is measured on every channel with a 3 bit FADC It is inside a dipole and gives a crude standalone momentum

13. Klaus Honscheid 13 Ohio State University Pixels – Close up of 3/31 stations 50  m x 400  m pixels - 30 million total Two pixel planes per station (supported on a single substrate) Detectors in vacuum Half planes move together when Tevatron beams are stable. 10 cm

14. Klaus Honscheid 14 Ohio State University Pixel Readout Chip FPIX1 Different problem than LHC pixels: 132 ns crossing time (vs. 25ns)  easier Very fast readout required  harder R&D started in 1997 Two generations of prototype chips (FPIX0 & FPIX1) have been designed & tested, with & without sensors, including a beam test (1999) in which resolution <9  was demonstrated. New “deep submicron” radiation hard design (FPIX2):Three test chip designs have been produced & tested. Expect to submit the final design ~Dec. 2001 A pixel 7.2 mm Test outputs 8 mm Readout

15. Klaus Honscheid 15 Ohio State University Pixel Test Beam Results Track angle (mr) No change after 33 Mrad (10 years, worst case, BTeV) Analog output of pixel amplifier before and after 33 Mrad irradiation. 0.25  CMOS design verified radiation hard with both  and protons.

16. Klaus Honscheid 16 Ohio State University Pixel detectors are hybrid assemblies Sensors & readout “bump bonded” to one another. Readout chip is wire bonded to a “high density interconnect” which carries bias voltages, control signals, and output data. Micrograph of FPIX1: bump bonds are visible Sensor Readout chip HDI Sensor (5 readout chips underneath) Wire bonds

17. Klaus Honscheid 17 Ohio State University Distribution in L/  of Reconstructed B s Primary-secondary vertex separation Minus generated.  = 138   proper (reconstructed) -  proper (generated)  = 46 fs Mean = 44 Physics Performance of Pixel Detector

18. Klaus Honscheid 18 Ohio State University The BTeV Level I Detached Vertex Trigger Three Key Requirements: –Reconstruct every beam crossing, run at 7.6 MHz –Find primary vertex –Find evidence for a B decaying downstream of primary vertex Five Key Ingredients: –A vertex detector with excellent spatial resolution, fast readout, and low occupancy –A heavily pipelined and parallel processing architecture well suited to tracking and vertex fining –Inexpensive processing nodes, optimized for specific tasks within the overall architecture ~3000 CPUs –Sufficient memory to buffer the vent data while calculations are carried out ~1 Terabyte –A switching and control network to orchestrate the data movement through the system

19. Klaus Honscheid 19 Ohio State University Information available to the L1 vertex trigger p p p p

20. Klaus Honscheid 20 Ohio State University Track segments found by the L1 vertex trigger “entering” track segment “exiting” track segment

21. Klaus Honscheid 21 Ohio State University FPGA Associative Memory DSP Track Farm (4 DSPs per crossing) Average Latency: 0.4  s Average Latency: 55  s DSP Vertex Farm (1 DSP per crossing) Average Latency: 77  s Level 1 Vertex Trigger: FPGAs: ~ 500 Track Farm DSPs: ~ 2000 Vertex Farm DSPs: ~ 500 Level 2/3 Trigger 2500 high performance LINUX processors Pixel System Pattern Recognition Track Reconstruction Vertex Reconstruction Block Diagram of the Level 1 Vertex Trigger

22. Klaus Honscheid 22 Ohio State University Pixel Trigger Performance Select number (N) of detached tracks typically pt> 0.5 GeV, N = 2 Select impact parameter (b) w.r.t. primary vertex typically  (b) = 6 Options include cuts on vertex, vertex mass etc. 74% 1% N=1 N=2 N=3 N=4 N=1 N=2 N=3 N=4

23. Klaus Honscheid 23 Ohio State University Trigger Simulation Results L1 acceptance: 1% 2% Profile of accepted events 4 % from b quarks including 50-70% of all “analyzable” b events 10 % from c quarks 40 % from s quarks 45 % pure fakes L2/L3 acceptance: 4 % 4000 Hz output rate 200 Mbytes/s Level 1 Efficiency on Interesting Physics States

24. Klaus Honscheid 24 Ohio State University Trigger/DAQ BTeV Data Acquisition Overview

25. Klaus Honscheid 25 Ohio State University Importance of Particle Identification Cherenkov angle vs Mom. P Gas Liquid

26. Klaus Honscheid 26 Ohio State University Two identical RICH detectors Components: –Gaseous Radiator (C 4 F 10 ) –Liquid Radiator (C 5 F 12 ) –Spherical mirrors –Photo-detectors (PM + HPD) –Vessel to contain gas volume Cherenkov photons from B o  +   and rest of the beam collision Ring Imaging Cherenkov (RICH)

27. Klaus Honscheid 27 Ohio State University RICH Readout: Hybrid Photodiodes (HPD) Commercial supplier from Holland (DEP) A number of prototypes was successfully produced and tested for CMS New silicon diode customized for BTeV at DEP (163 pixels per HPD) Challenges: –high voltages (20 kV!) –Signal ~5000e -  need low noise electronics (Viking) –In the hottest region up to 40 channels fire per tube –About 2000 tubes total (cost)

28. Klaus Honscheid 28 Ohio State University Use of RICH to extend Lepton Identification While the full detector aperture is 300 mr, the acceptance of the electromagnetic calorimeter and muon detector is only 200mr The RICH, however, has both electron-pion and muon-pion discrimination at low momentum. The wide angle particles are mostly at low momentum! This gains us a factor of 2.4 for single lepton id and 3.9 if we require both leptons to be identified

29. Klaus Honscheid 29 Ohio State University Electromagnetic Calorimeter The main challenges include Can the detector survive the high radiation environment ? Can the detector handle the rate and occupancy ? Can the detector achieve adequate angle and energy resolution ? BTeV now plans to use a PbWO 4 calorimeter Developed by CMS for use at the LHC Large granularity Block size 2.7 x 2.7 x 22 cm 3 (25 X o ) ~11000 crystals Photomultiplier readout (no magnetic field) Pre-amp based on QIE chip (KTeV) Energy resolution Stochastic term 1.8% Constant term 0.33% Position resolution

30. Klaus Honscheid 30 Ohio State University PbWO 4 Calorimeter Properties Property Value Density(gm/cm 2 ) 8.28 Radiation Length(cm) 0.89 Interaction Length(cm) 22.4 Light Decay time(ns) 5(39%) (3components) 15(60%) 100(1%) Refractive index 2.30 Max of light emission 440nm Temperature Coefficient (%/ o C) -2 Light output/Na(Tl)(%) 1.3 Light output(pe/MeV) into 2” PMT 10 Property Value Transverse block size 2.7cm X 2.7 cm Block Length 22 cm Radiation Length 25 Front end Electronics PMT Inner dimension +/-9.8cm (X,Y) Energy Resolution: Stochastic term 1.8% Constant term 0.33% Spatial Resolution: Outer Radius 140 cm--215 cm $ driven Total Blocks/arm 11,500

31. Klaus Honscheid 31 Ohio State University Electromagnetic Calorimeter Tests Lead Tungstate Crystals from Shanghai, Bogoroditsk, other vendors Verify resolution, test radiation hardness (test beam at Protvino) Test uniformity Block from China’s Shanghai Institute 5X5 stack of blocks from Russia ready for testing at Protvino

32. Klaus Honscheid 32 Ohio State University Preliminary Testbeam Results Resolution (energy and position) close to expectations Some non-uniformity in light output more Radiation Hardness studies Position Resolution Energy Resolution

33. Klaus Honscheid 33 Ohio State University EM calorimetry * CLEO barrel  =89% radius

34. Klaus Honscheid 34 Ohio State University Muon System track from IP toroid(s) / iron ~3 m 2.4 m half height Provides Muon ID and Trigger –Trigger for interesting physics states –Check/debug pixel trigger fine-grained tracking + toroid –Stand-alone mom./mass trig. –Momentum “confirmation” Basic building block: Proportional tube “Planks”

35. Klaus Honscheid 35 Ohio State University Physics Reach (CKM) in 10 7 s J/  +  - Reaction B (B)(x10 -6 ) # of EventsS/B Parameter Error or (Value) Bo+-Bo+- 4.5 14,600 3 Asymmetry 0.030 B s  D s K - 300 7500 7  8 o B o  J/  K S J/  l + l  - 445 168,000 10 sin(2  ) 0.017 B s  D s  - 3000 59,000 3 x s (75) B -  D o (K +  - ) K - 0.17 170 1 B -  D o (K + K - ) K - 1.1 1,000>10  13 o B-KS -B-KS - 12.1 4,600 1 <4 o + B o  K +  - 18.8 62,100 20  theory errors Bo+-Bo+- 28 5,400 4.1 BoooBooo 5 780 0.3  ~4 o B s  J/  330 2,800 15 B s  J/  670 9,800 30  0.024

36. Klaus Honscheid 36 Ohio State University Concluding Remarks PAC Recommendation “ … BTeV has designed and prototyped an ambitious trigger that will use B decay displaced vertices as its primary criterion. This capability, together with BTeV’s excellent electromagnetic calorimetry and particle ID and enormous yields, will allow this experiment to study a broad array of B and B s decays. BTeV has a broader physics reach than LHCb and should provide definitive measurements of CKM parameters and the most sensitive tests for new physics in the flavor sector.” C0 Hall at the Tevatron

37. Klaus Honscheid 37 Ohio State University Additional Transparencies

38. Klaus Honscheid 38 Ohio State University Changes wrt Proposal in Event Yields & Sensitivities We lost one arm, factor = 0.5 We gained on dileptons –From RICH ID –in proposal we used only  +  -, now we include e + e - –factor = 2.4 (or 3.9), depending on whether analysis used single (dilepton) id We gained on bandwidth, factor = 1.15 Gained on  D 2 for B s only, factor = 1.3

39. Klaus Honscheid 39 Ohio State University Examples mode Yield prop Yield factor Yield one-arm quan/Err prop (  D 2 ) quan/Err one arm(  D 2 ) B o  J/  K s 80,5000.5*3.9* 1.15=2.24 168,000 sin(2  )/ 0.025 (0.10) sin(2  )/ 0.017 (0.10) B s  J/  () 9,940 0.5*2.4* 1.15=1.38 12,600 sin(2  )/ 0.033 (0.10) sin(2  )/ 0.024 (0.13) B s  D s K - 13,100 0.5*1.15 =0.58 7,500  /  6 o (0.10)  /  8 o (0.13)

40. Klaus Honscheid 40 Ohio State University Reconstructed Events in New Physics Modes: Comparison of BTeV with B-factories Mode BTeV (10 7 s) B-fact (500 fb -1 ) YieldTaggedS/BYieldTaggedS/B B s  J/   12650 1645>15 - - B-K-B-K- 11000 >10 700 4 BoKsBoKs 2000 200 5.2 250 75 4 B o  K*  +  - 2530 11 ~50 3 Bs +-Bs +- 6 0.7>15 0 Bo+-Bo+- 1 0.1>10 0 D *+   + D o, D o  K  + ~10 8 large 8x10 5 large

41. Klaus Honscheid 41 Ohio State University Comparisons with LHCb Advantages of LHCb  b 5x larger at LHC, while  t is only 1.6x larger –The mean number of interactions per beam crossing is 3x lower at LHC, when the FNAL bunch spacing is 132 ns Advantages of BTeV (machine specific) –The 25 ns bunch spacing at LHC causes increased electronic noise. It makes 1st level detached vertex triggering more difficult; in fact LHCb only does vertexing in level 2

42. Klaus Honscheid 42 Ohio State University Comparisons with LHCb II –The 7x larger LHC beam energy causes problems: much larger range of track momenta that need to be analyzed and large increase in track multiplicity, which causes triggering and tracking problems –The long interaction region at FNAL,  =30 cm compared with 5 cm at LHC, somewhat compensates for the larger number of interactions per crossing, since the interactions are well separated –There is an ion-trapping problem that stops them from moving their silicon closer than ~1 cm (compared to 6 mm for BTeV)

43. Klaus Honscheid 43 Ohio State University Comparisons with LHCb III Advantages of BTeV (detector specific) –BTeV has vertex detector in magnetic field which allows rejection of high multiple scattering (low p) tracks in the trigger –BTeV is designed around a pixel vertex detector which has much less occupancy, and allows for a detached vertex trigger in the first trigger level. Important for accumulation of large samples of rare hadronic decays and charm physics. Allows BTeV to run with multiple interactions per crossing, L in excess of 2x10 32 cm -2 s -1 –BTeV will have a much better EM calorimeter –BTeV is planning to read out 5x as many b's/second

44. Klaus Honscheid 44 Ohio State University Specific Comparisons with LHC-b Yields in important final states Mode BR YieldS/B Yield S/B B s  D s K - 3.0x10 -4 7530 77660 7 Bo+-Bo+- 2.8x10 -5 5400 4.12140 0.8 BoooBooo 0.5x10 -5 776 0.3 880 not known BTeV LHC-b

45. Klaus Honscheid 45 Ohio State University Fundamentals: Decay Time Resolution Excellent decay time resolution –Reduces background –Allows detached vertex trigger The average decay distance and the uncertainty in the average decay distance are functions of B momentum: =  c    = 480  m x p B /m B  from b L/  direct  CDF/D0 region LHC-b region

46. Klaus Honscheid 46 Ohio State University Trigger

47. Klaus Honscheid 47 Ohio State University

48. Klaus Honscheid 48 Ohio State University