1. RICH 2002, Pylos, Greece1 Steven Blusk for the BTeV Collaboration Design of the BTeV RICH and its Expected Performance

2. RICH 2002, Pylos, Greece2 The BTeV Collaboration Belarussian State- D.Drobychev, A. Lobko, A. Lopatrik, R. Zouversky UC Davis - J. Link, P. Yager Univ. of Colorado at Boulder J. Cumalat Fermi National Lab J. Appel, E. Barsotti, CN Brown, J. Butler, H. Cheung, G. Chiodini, D. Christian, S. Cihangir, I. Gaines, P. Garbincius, L. Garren, E. Gottschalk, A. Hahn, G. Jackson, P. Kasper, P. Kasper, R. Kutschke, SW Kwan, P. Lebrun, P. McBride, L. Stutte, M. Votava, M. Wang, J. Yarba Univ. of Florida at Gainesville P. Avery University of Houston K. Lau, B. W. Mayes, J. Pyrlik, V. Rodriguez, S. Subramania Illinois Institute of Technology RA Burnstein, DM Kaplan, LM Lederman, HA Rubin, C. White Univ. of Illinois- M. Haney, D. Kim, M. Selen, J. Wiss Indiana University RW Gardner, DR Rust Univ. of Insubria in Como- P. Ratcliffe, M. Rovere INFN - Frascati- M. Bertani, L. Benussi, S. Bianco, M. Caponero, F. Fabri, F. Felli, M. Giardoni, A. La Monaca, E. Pace, M. Pallota, A. Paolozzi, A. Scicutelli INFN - Milano – G. Alimonti, M. Citterio, P. D’Angelo, S. Magni, D. Menasce, L. Moroni, D. Pedrini, M. Pirola, S. Sala, L. Uplegger INFN - Pavia - G. Boca, G. Cossail, E. Degliantoni, PF Manfredi, M. Manghisoni, M. Marengo, L. Ratti, V. Re, V. Speziali, G. Traversi INFN - Torino N. Cartiglia, R. Cester, F. Marchetto, R. Mussa, N. Pastrone IHEP Protvino, Russia A. Derevschikov, Y. Goncharenko, V. Khodyrev, A. Meschanin, L. Nogach, K. Shestermanov, L. Soloviev, 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, BP. Zhang, JW 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, L. Tiankuan, T. Yang, XQ Yu Shandong Univ. (China) CF Feng, Yu Fu, Mao He, JY Li, L. Xue, N. Zhang, & XY Zhang Southern Methodist University - T. Coan SUNY Albany - M. Alam Syracuse University M. Artuso, C. Boulahouache, O. Dorjkhaidav K. Khroustalev, R.Mountain, R. Nandakumar, T. Skwarnicki, S. Stone, JC Wang, H. Zhao Univ. of Tennessee K. Cho, T. Handler, R. Mitchell Tufts Univ. – A. Napier Vanderbilt University W. Johns, P. Sheldon, K. Stenson, E. Vaandering, M. Webster Wayne State University G. Bonvicini, D. Cinabro University of Wisconsin M. Sheaff Yale University J. Slaughter York University S. Menary

3. RICH 2002, Pylos, Greece3 Physics of BTeV  BTeV will vastly improve the constraints on the CKM angles by making precision measurements of both the sides and the angles    over-constrain (  ).   Measurements and searches for rare and SM forbidden decays  “Beyond the SM” Physics.  B factories will provide valuable input on sin(2  ) and V ub, but they cannot compete with a hadron collider on measuring , and searches for new physics (even by 2007). - They don’t produce B S -  (bb) is ~10,000X larger at the Tevatron than at  (4S)

4. RICH 2002, Pylos, Greece4 B Production at the Tevatron b production angle The higher momentum b are at larger   Pseudo-rapidity  b production peaks at large angles with large bb correlation b cross section ~ 100  b at 2 TeV  2x10 11 b’s per 10 7 sec at L =2x10 32 cm -2 s -1.

5. RICH 2002, Pylos, Greece5 B Physics Detector “Wish List” Detector Property Precision 3D Tracking Excellent Particle ID (K, , p, e,  ) Excellent calorimetry Detached Vertex trigger at lowest level trigger BTeV    

6. RICH 2002, Pylos, Greece6 The BTeV Detector

7. RICH 2002, Pylos, Greece7 RICH Specifications  Momentum Range of Interest * p > 2-3 GeV for CP tagging * p < 70 GeV  clean separation of 2-body modes: B  , K , KK.  Minimize material in front of ECAL  Longitudinal space available ~3 meters  Desirable to detect Cerenkov photons in the visible range (minimize chromatic error, less sensitive to contaminants, etc)  Well-suited for a Ring Imaging Cerenkov Detector Tagging kaons in BTeV Acc.

8. RICH 2002, Pylos, Greece8 Radiators Large momentum coverage requires a low index of refraction  gas radiator We chose C 4 F 10 because: * heaviest gas which has high transparency in the visible * wide usage in other HEP expt’s (e.g. Delphi, HERA-B, HERMES, LHC-b). For momenta below 9.5 GeV/c neither K nor P radiate in C 4 F 10  Separate liquid radiator for K/P separation below 9.5 GeV/c Large momentum coverage requires a low index of refraction  gas radiator We chose C 4 F 10 because: * heaviest gas which has high transparency in the visible * wide usage in other HEP expt’s (e.g. Delphi, HERA-B, HERMES, LHC-b). For momenta below 9.5 GeV/c neither K nor P radiate in C 4 F 10  Separate liquid radiator for K/P separation below 9.5 GeV/c

9. RICH 2002, Pylos, Greece9 The BTeV RICH Arrays of 163-channel HPDs (~1000 in total) PMT Arrays (~5,000 in total) Spherical mirrors C 5 F 12 Liquid Radiator C 4 F 10 gas volume  Photons from gas are reflected off mirrors and focused at the HPD plane.  Photons from liquid are directly detected in the PMTs.

10. RICH 2002, Pylos, Greece10 Photon Angles Track from Interaction HPD Array PMT Array Liquid radiator photons are detected in PMT array. Liquid Radiator Gas Radiator Volume Gas radiator photons are detected in HPD array. Mirror

11. RICH 2002, Pylos, Greece11 Gas Radiator Gas: C 4 F 10 (n=1.00138): * K/  separation for 3 < p <70 GeV * P/K separation for 9.5 < p < 70 GeV   c (  ) ~ 0.43 mrad @ 70 GeV  Must keep  C )/trk < 0.13 mrad  N(  ) detected ~ 65 (simulation)  Total uncertainty per photon must be kept below ~1 mrad.  Requires ~1.5 mm segmentation  Well-suited for HPDs No P/K separation below ~ 9.5 GeV with gas alone

12. RICH 2002, Pylos, Greece12 Detecting Gas Photons with HPDs * See talk by Ray Mountain  Started with 61-channel HPD that LHC-b and DEP developed.  We worked with DEP to develop 163-ch version| which would meet BTeV’s requirements.  Cross-focused onto hexagonal pixels  Signal: ~5000 e - in Silicon.  Readout system is being developed by Syracuse in collaboration with IDE AS Norway. HPD e  163 channels ~1.5 mm -20 kV

13. RICH 2002, Pylos, Greece13 HPD Hexad Mu-metal shield Readout Boards are mounted here HPD VA_BTEV ASICs (AS&D) Full HPD Array

14. RICH 2002, Pylos, Greece14 HPD Readout  VA_BTeV ASIC being developed in collaboration with IDE AS Norway (independent from HPD development)  Initial tests indicate that ~500 e - noise level be achieved.  Threshold for each channel is adjustable.  Readout is binary (ON or OFF)  Testing of first prototypes is underway at Syracuse. HPD Readout Board VA_BTeV chip

15. RICH 2002, Pylos, Greece15 More on HPD Readout  Discharge of FE chip requires 2 beam crossings, so a hit channel is dead for the next crossing.  Simulated effect @ L=2x10 32 cm -2 s -1. Find <10% loss of photons even in the busiest regions. (Much smaller elsewhere) HPD# Y X Number of hit channels in consecutive beam crossings per 163 channels

16. RICH 2002, Pylos, Greece16 Liquid Radiator C 5 F 12 (n=1.24): * Extends P/K separation to p<9.5 GeV * Extends K/  separation into the p<3 GeV range  c (  ) ~ 5.3 mrad @ 9 GeV Must keep  C )/trk<1.7 mrad N(  ) detected ~ 15 (simulation)  Total uncertainty per photon must be kept below ~7 mrad  Separate PMT system (3” PMT is acceptable)

17. RICH 2002, Pylos, Greece17 Detecting Liquid Photons -- PMTs  Expect to use 3” tubes.  Shielding necessary ( |B| < 15 G in PMT region)  Expect   (   c ) ~ 6 mrad, N(  ~15/trk   (  trk c ) ~ 1.6 mrad PMT Layout in BTeV Mu-metal shields 3”

18. RICH 2002, Pylos, Greece18 Magnetic Shielding of PMTs Unshielded B Trans. PMTs from 4 different manufacturers 4.0 12.0 45.0 Shielded B Long. B max =15 G

19. RICH 2002, Pylos, Greece19 Preliminary Conceptual Tank Design PMT Arrays HPD Arrays

20. RICH 2002, Pylos, Greece20 Liquid Radiator Conceptual Design  1 cm of C 5 F 12  3 mm Carbon Fiber front window & 3 mm quartz back window  Split into 5 volumes to reduce pressure.  Structure is reinforced by CF posts  Total Material Budget: X 0 ~ 8.7%  Simulations indicate negligible impact on  0 reconstruction since electrons from  conversions are only in a very weak magnetic field.

21. RICH 2002, Pylos, Greece21 Progress with Mirrors  Measurements being taken on the test bench of the TA2 group at CERN.  Several mirrors under study  COMPAS: glass, glass+foam back.,  CMA: Carbon fiber  Initial tests show that they meet spot size spec. R curv =660 cm Work being done by INFN Torino group ~60 cm

22. RICH 2002, Pylos, Greece22 Expected Performance from Simulations

23. RICH 2002, Pylos, Greece23 Efficiency vs Fake Rate Clean separation of B   from B  K  and B  KK For example:  (B   ): 80% K  Rejection ~ 95% KK Rejection > 99%  The latter is important because B s  KK lies on top of B   signal B   Simulation w/ 2 minimum bias events. Gas Radiator & HPDs K+-K+- K+K-K+K-

24. RICH 2002, Pylos, Greece24 Low Momentum K/P separation using Liquid Radiator & PMTs K and P cannot be separated below 9.5 GeV/c in gas system. Our simulations showed that we could improve  D 2 by ~25% for B S and ~10% for B 0 using liquid radiator. Mom. < 9 GeV/c

25. RICH 2002, Pylos, Greece25 Expectations for  D 2 BSBS CP side Recoiling b-hadron K+K+ Away-side tags K –,  -, e -, p,    jet charge Same-side particle tag K + Error on CP Asymmetry Tag Type D2D2  SS Away Side Kaon Tag 6.0%5.8 % Same Side Kaon (Pion) Tag 1.1%4.5% Away Side Muon Tag 0.8%1.3% Jet Charge 1.4%0.4% Total9.2 %12.1 % BTeV Expected 10 %13 %

26. RICH 2002, Pylos, Greece26 Test Beam – May 2003 Concrete Support Blocks HPD Enclosure Mirror Assembly Front Entrance Window  ~15 HPDs to cover full Cerenkov ring  ~100 GeV  beam  Will measure: * resolution on Cerenkov angle * photon yield  We’ll also scan the mirror to check sensitivity  Construction underway.

27. RICH 2002, Pylos, Greece27 Summary  The BTeV RICH uses :  gas system: C 4 F 10 gas and HPDs, and  liquid system: C 5 F 12 and PMTs to achieve excellent  K/P separation for all relevant momenta less than 70 GeV/c.  Recent addition of the liquid radiator system will improve  D 2 for CP tag by ~25% for B S and ~10% for B 0.  Initial tests of HPDs/PMTs look encouraging (see talk by R. Mountain)  Test beam next year to validate detector design and simulations.

28. RICH 2002, Pylos, Greece28 Why did we punt on Aerogel?  Both gas & aerogel photons were detected in the HPDs  After removing photons which were consistent with more than 1 track, aerogel provided essentially no K/P separation  The aerogel rings have too few photons to compete with the bright gas rings Low mult. event High mult. event

29. RICH 2002, Pylos, Greece29 Alternate solution for detecting gas photons (MA-PMT16)  Larger active region than 1 st gen.  lens system not required  Viable backup to HPDs  slightly worse position resolution..  Currently being tested at Syracuse.