Status and prospects of the LHCb Experiment Neville Harnew University of Oxford Beauty 2002, Santiago de Compostela 21st June 2002 On behalf of the LHCb Collaboration

2 N.Harnew 21st June 2002 Beauty 2002 France: FR Annecy, Clermont-Ferrand, CPPM Marseille, LAL Orsay Germany: DE Tech. Univ. Dresden, Phys. Inst. Univ. Heidelberg, KIP Univ. Heidelberg, MPI Heidelberg, Italy: IT Bologna, Cagliari, Ferrara, Firenze, Frascati, Genoa, Milan, Univ. Rome I (La Sapienza), Univ. Rome II (Tor Vergata) Netherlands: NL NIKHEF Poland: PL Cracow Inst. Nucl. Phys. & Tech. Univ, Warsaw Soltan Inst. Spain: ES Univ. Barcelona, Univ. Santiago de Compostela Switzerland: CH Univ. Lausanne, Univ. Zürich UK: GB Univ. Bristol, Univ. Cambridge, Univ. Edinburgh, Univ. Glasgow, IC London, Univ. Liverpool, Univ. Oxford, RAL CERN Brazil: BR UFRJ, CPBF China: CN IHEP(Beijing), Tsinghua Univ. Russia: RU BINP, INR, ITEP, IHEP, PNPI Romania: RO IFIN-HH (Bucharest) Ukraine: UA Inst. Phys. Tech. (Kharkov), Inst. Nucl. Research (Kiev) TechnicalEspoo-Vantaa Inst. Tech. (Finland), Geneva Engineering School (Switzerland) Associates:CEFET-RJ (Brazil) The LHCb Collaboration (45+3 institutes)

3 N.Harnew 21st June 2002 Beauty 2002 OUTLINE n Introduction n The LHCb experiment wStatus of the experiment wDetector optimization  LHCb-light  Trigger strategy n Physics prospects  Measurement of angle  wImportance of high statistics n Summary and conclusions

4 N.Harnew 21st June 2002 Beauty 2002 n Standard Model wpredicts large CP violating asymmetries for B mesons n CP violation predicted in many (often v.rare) decays wneed large samples of B d, B u, B s mesons, B baryons wNeed consistency checks Physics motivation of LHCb Unitarity Triangles B d 0     B d 0    B d 0  DK *0 B S 0  D S K B d 0  D*  B S 0  D S  B d 0  J/  K S 0 B S 0  J/ 

5 N.Harnew 21st June 2002 Beauty 2002 CP violation in 2007     |V td /V ts | |V ub /V cb |  (sin2  ) ~ 0.02 (world average)  (sin2  ) ~ 0.1  (  ) ~ v.large ? |V td /V ts | from  m S by CDF & D0 limited by theory n |V ub /V cb | from b->u by BaBar & Belle

6 N.Harnew 21st June 2002 Beauty 2002 Advantage of LHC bb angular distribution LHC Luminosity LHCb = 2 x10 32 cm -2 s -1  bb = 500  b  inelastic ~ 80 mb bb / 10 7 s (or 1 million per 10s)

7 N.Harnew 21st June 2002 Beauty 2002 LHCb Experiment (“classic”) n Acceptance w10 – (250) 300 mrad (non) – bending plane n Particle ID   -K separation 1<p<150 GeV/c n Vertexing wProper time resolution  43 fs B s -> D s  (K)  30 fs B s -> J/  

8 N.Harnew 21st June 2002 Beauty 2002 Status of construction & design n Experimental area n Magnet n VELO n RICH n Tracking system n Calorimeter n Muon system n Re-optimization of the detector

9 N.Harnew 21st June 2002 Beauty 2002 Experimental area Pit 8: DELPHI dismantling completed. Necessary modification work started. POINT 8 - UX85 March 2002 Pillar Head Wall

10 N.Harnew 21st June 2002 Beauty 2002 Magnet n Warm magnet Al conductor w∫B.dl ~ 4 Tm n All contracts placed and signed n Production well underway Bending of the Al conductor

11 N.Harnew 21st June 2002 Beauty 2002 ~1 m VErtex LOcator n Si strip detectors, single sided, read-out 220  m thick, wedges. n Now 21 stations mounted inside the vacuum tank. ~200k readout channels. n Vertex detector crucial in ALL time-dependent CP violation studies. Si detectors

12 N.Harnew 21st June 2002 Beauty 2002 VELO test beam radial azimuth Test beam Reconstruction of Primary Vertex using 2d tracks  z ~ 79  m Test beam Reconstruction of Primary Vertex using 2d tracks  z ~ 79  m

13 N.Harnew 21st June 2002 Beauty 2002 RICH System n 2 RICH detectors 3   K separation 3-80 GeV/c 2   K separation GeV/c Aerogel C 4 F 10 CF 4 L cm n  mrad  GeV K GeV

14 N.Harnew 21st June 2002 Beauty 2002 Photon detection with HPDs -20 kV CF 4 Aerogel large rings C 4 F 10 small rings 1024 pixel prototype n Prototype pixel HPD (LHC speed) being developed n Major review end June 2002 n Backup MAPMT

15 N.Harnew 21st June 2002 Beauty 2002 And in reality …

16 N.Harnew 21st June 2002 Beauty 2002 RICH-2 Engineering Design n 3-D CAD model n Assembly of Prototype window

17 N.Harnew 21st June 2002 Beauty 2002 Power of particle ID n Purity = 84% ; Efficiency = 90% B   +  -

18 N.Harnew 21st June 2002 Beauty 2002 LHCb Inner & Outer Tracking Outer tracker n Straw tubes n 5mm diameter, occupancy <10% n 3m Prototype installed in HERA-B Inner tracker n Now full silicon soln. n Tests in progress

19 N.Harnew 21st June 2002 Beauty 2002 n ECAL – Shashlyk type (+ preshower) n 5952 cells 25 X 0, 1.1  depth  E /E = 0.10/sqrt(E) n Mass production started, ~30% modules produced. LHCb Calorimeters n HCAL – Tile calorimeter n 1468 cells 5.6  E /E = 0.80/sqrt(E) n Module 0 built and tested n Mass production started

20 N.Harnew 21st June 2002 Beauty 2002 Muon system Outer region RPCs Rate < 1kHz/cm 2 Muon system n 5 stations n 900 MWPCs n 480 RPC chambers n Production in preparation Inner & outer region MWPC

21 N.Harnew 21st June 2002 Beauty 2002 Detector optimization n LHCb material budget increased significantly since Technical Proposal. LHCb has been reoptimized. wBeampipe Al -> Be-Al alloy  possibility of first beampipe cone all Be wVELO reduced number of stations 25 -> 21 & thinner Si  Was 0.19 X 0 ( ) ; Now 0.18 X 0 wRICH-1 composite mirror and mirror support outside acceptance.  Was 0.14 X 0, ( ) ; Now X 0 wTracking stations from 9 -> 4  Now 0.27 X 0, ( ) ; Now 0.12 X 0 n Trigger optimization : B-field to provide P T information. n New RICH-1 design required by presence of B-field.

22 N.Harnew 21st June 2002 Beauty 2002 LHCb Light n No tracking stations in magnet region n “Vertical” RICH-1 n RESULT : an improved detector

23 N.Harnew 21st June 2002 Beauty 2002 LHCb Light tracking n Reduce tracking stations:- n Track efficiency and ghost rates improved with fewer secondary interactions. Preliminary conclusions B   +  - sample

24 N.Harnew 21st June 2002 Beauty 2002 LHCb trigger system high P T muonshigh P T electrons high P T hadrons high P T  /  0 pile-up veto Level-0 decision unit Muon SystemCalorimeter System pile-up vertex detector 40 MHz Level-1 trigger unit VELO 1 MHz All the detector Higher Levels 40 kHz (up to 100 kHz) Level-0 Level-1 Vertex trigger Levels-2&3

25 N.Harnew 21st June 2002 Beauty 2002 Optimized Level-1 trigger n Include Level-0 information  B     improved by factor 2 n Add p T information wAllow to work at low o/p rates (5-40) kHz wHigh signal efficiencies Work in progress : B     Signal efficiency Minimum bias retention TP L1 algorithm L1 with L0 info L1 with p T info

26 N.Harnew 21st June 2002 Beauty 2002 n B field in VELO region n Si station TT1 has 10% of B y n Momentum resolution using VELO tracks & TT1 wS(1/p)~0.2p /GeV B-field in RICH-1 region VELO RICH1

27 N.Harnew 21st June 2002 Beauty 2002 Major re-design of RICH-1 n 2-mirror geometry n Magnetic shielding box n Retain Aerogel & C 4 F 10

28 N.Harnew 21st June 2002 Beauty 2002 LHCb Physics performance n Importance of redundancy n Importance of particle ID n Importance of B S modes n Importance of high statistics n Performance summary table Re-optimization of LHCb currently in progress. All performance figures are pre - detector optimization. Measurement of 

29 N.Harnew 21st June 2002 Beauty 2002 Measurement of angle  (1) n Expect 2400 events in 1 year of data taking     Depends on   and strong phase diff.  ( ) B s -> D s K  Rate asymmetries measure angle  n Theoretically clean

30 N.Harnew 21st June 2002 Beauty 2002 Measurement of  (2) A CP = A dir cos  mt + A mix sin  mt n ~5k events per year in each channel Invoke U-spin symmetry & relate  and KK coefficients to extract  n (Fleischer CERN-TH/ )  ~ 5 – 10 o [theory]  From B d     , B s  K  K 

31 N.Harnew 21st June 2002 Beauty 2002 Measurement of  (3) n 4 Time-dependent decay rates n Relies on efficient hadron trigger n CP asymmetry very small (need large statistics)  - Inclusive D* reconstruction ~ 500 k events/year with S/B~5 - Add D*a 1 channels ~ 360 k events/year - Get  from B->J/  K s (2  +  ) in degrees  (2  +  ) in degrees 1 year5 years B d  D   , D    Measures 2  +  ( ) Assumes perfect knowledge (blue) and 10% uncertainty (red) in |  |

32 N.Harnew 21st June 2002 Beauty 2002 LHCb sensitivity per year :  ~ 10 O Determination of  from the measurement of 6 time-integrated decay rates : B d  D 0 K * 0, B d  D 0 K * 0, B d  D 0 CP=+1 K * 0 K +  - K -  + K+-,+-K+-,+- Visible BR’s ~    Measurement only possible with forward detector with particle ID B d  D 0 K *0 signal From B d 0  D 0 K *0 Measurement of  (4)

33 N.Harnew 21st June 2002 Beauty 2002 B -> J/  K s  world (sin 2  ) ~ 0.02 by 2006 n What will LHCb bring to this topic ? wSTATISTICS !  LHCb (sin 2  ) ~ 0.02 in 1 year n True precision measurement of this parameter n Eg. Fit for direct CP- violating contribution

34 N.Harnew 21st June 2002 Beauty 2002 LHCb performance 64% 35% 45% n Performance figures are for: n 1 year’s running n Reconstructable events n Event yields are for tagged events n Performance figures are currently being re-evaluated. Preliminary

35 N.Harnew 21st June 2002 Beauty 2002 After 1 year of LHCb (2008)

36 N.Harnew 21st June 2002 Beauty 2002 or maybe … … maybe  will provide a surprise

37 N.Harnew 21st June 2002 Beauty 2002 Summary n LHCb will perform a precision study of CP violation. A probe for physics beyond the SM. n Redundancy of measurements in many channels. Good particle ID, vertexing, and efficient & flexible trigger essential. n Detector construction has started and progressing well. Good balance of advanced and proven technologies. n LHCb will be ready for data-taking at LHC startup in 2007.