Status of the LHCb experiment Elie Aslanides CPPM, IN2P3-CNRS et Université de la Méditerranée, France on behalf of the LHCb Collaboration LISHEP Itacuruçá, Rio de Janeiro, April 4, 2006
Introduction LHCb detector status Expected performances Conclusion
Introduction LHCb is the dedicated B physics experiment at the LHC devoted to the precision study of CP violation and rare decays. The LHCb Collaboration includes 47 institutes from 15 countries and more than 600 members. •Extend B-physics results obtained in B-factories and the Tevatron •Search for new physics in a complementary way to ATLAS/CMS LHCb may be the only running Beauty Physics experiment, after the B-factories (if no Super B-factories are approved) !
Baseline physics goals of LHCb…a second generation experiment With a luminosity < L > ≈ 2×10 32 cm −2 s −1 , 10 7 s/year, 2 fb -1 /year, LHCb should reach in 5 years unprecedented precisions σ (>5 y) SM (expect) φ s (B s → ccss) ~ 0.013 ~ 0.035 γ ( D s K, D 0 K *0 ) ~1 ° ~60 ° (tree only) γ (ΚΚ+ππ ) ~2 ° ~60 (tree + penguin) Br(B s →µ + µ − ) ~0.7 ×10 −9 ~ 3.5×10 −9 A FB ( s ) B d → K ∗0 µ + µ − A FB ( s ) sensitive to NP 22k events expected >5y (Super-KEKB similar… by 2020!) ± 0.04 Belle 357 fb −1 114 events 1000 fb −1 by ~2009
Beauty production at the LHC At √ s = 14 TeV, pp collisions have large σ bb ~ 500 µ b but small compared to the total, σ bb / σ tot ~ 5·10 -3 interesting B decays have low b.r. ~10 -5 Bunch crossing rate at the LHC is 40 MHz pp interactions/crossing LHCb average L ~ 2 × 10 32 cm -2 s -1 1.0 Probability 0 → 2 fb -1 / year (10 7 s) 0.8 0.6 → 10 12 bb produced/year! 0.4 1 → most events due to single interactions 0.2 2 3 per bunch crossing! 4 10 31 10 32 10 33 Luminosity [cm − 2 s − 1 ]
Beauty production at the LHC Forward peaked, correlated " b anti-b" pair production" LHCb is a forward spectrometer (10 – 300 mrad) pT of B-hadron p T vs η for detected B hadrons ATLAS/CMS 10 2 100 µ b LHCb 230 µ b p p 10 1 -2 0 2 4 6 eta of B-hadron
Experimental requirements … � Efficient and flexible Trigger � High quality Event Reconstruction particle identification hadrons…, µ ’s and e’s, as well as γ ’s, π 0 ’s excellent tracking and vertexing good p, E, Mass and τ resolutions m m 0 1 ~ b b � Powerful Readout and on line processing ( HLT )
Spectrometer Dipole magnet Tracking system Muon system 250 mrad Calorimeters Vertex Locator 10 mrad p p RICH detectors
LHCb at Point 8 Offset Interaction Point Shielding wall Electronics + CPU farm Detectors can be moved away from beam-line for access
Introduction LHCb detector status Expected performances Conclusion
November 2005
The beam pipe… Located in the high rapidity region where particle density is high, it is a major source of secondaries! 3 Beryllium sections Stainless steel section UX85/1 UX85/2 UX85/3 UX85/4 1mm 1-2 mm 3-4 mm Stainless steel flanges VELO window and bellows Al flanges and bellows
Production is progressing well… VeLo window prototype UX 85/1 (Be) COMPLETED
UX 85/2 (Be) tested at IHEP, Protvino Acceptance tests NEG coating … UX 85/3 ( Be) under construction by Kompozit, Moscow, All components in production. Installation early summer’06, fits in general planning.
The magnet Warm dipole magnet ∫ B dl = 4 Tm Iron yoke 15 ton; Power 4.2 MW Nominal field reached on Nov. ‘04
Magnetic field measurements Dec. ’04; June ’05 including RICH1 shield and all iron Dec. ’05 [final and Polarity ± ] TT VeLo magnet • ∫ B dl in VELO-TT region needed for fast online p T 60 3D Hall probes • B inside RICH is ok for the HPD operation!
Vertex Locator Key element around the IP 8cm ~1m 8cm 21 stations of Silicon 300 µ -strip detectors r- φ geometry variable pitch [ r (40-102 µ ); φ (36-97 µ ) ] 172 k channels
VELO detector vacuum box … 300 µ AlMg3 RF shield for sensors + electronics guides the beams mirror charge suppresses dynamic vacuum phenomena suppresses electron multipacting RF box corrugations RF box corrugations
To give precise vertex reconstruction VELO approaches to 8 mm from beam Radiation ~1.5 10 14 n eq./cm2/y Expected lifetime ~3 years; Si to be replaced Detector stations in 2 retractable halves Complex mechanics to allow retraction during beam injection (~completed) VELO uses vacuum like a « roman pot » VELO operated at –5°C (CO2 cooling)
Sensors characteristics: n+n type, double metal layers 300 µ , laser cut FE electronics (Beetle chip) mounted on thin kapton, connected to the sensors via Pitch Adapters Modules production started ! should be completed ~end summer’06 RF boxes installed September ’06 Vacuum tests October ‘06 VELO modules installed in RF boxes >January ’07
Tracking… T1 T2 T3 Trigger Tracker Si µ -strip detector Outer Tracker 144 k channels Straw Tubes TT 56 k channels Inner Tracker Si µ -strip detector around the beam pipe 130 k channels
Trigger Tracker Four Si µ -strip detection layers, ~ 8 m 2 of silicon, covering the nominal LHCb acceptance. Arranged in two double layers (0°,+5°) and (-5°,0°) 30 cm apart. Together with VELO, the TT measures the p T of the high IP tracks for use in the trigger. Offline: decay tracks of long-lived neutral particles decaying outside the VELO fiducial volume. 500 µ silicon, CMS OB2-type sensors Strips: pitch 198 µ ; length 11, 22, 33 cm Radiation: ≤ 9×10 12 n eq /cm²/10 year Operated at 5°C
Almost all sensors and components in hand… TT support structure will be installed in April TT installation in UX85 between June and October ’06.
3 Tracking stations Outer Tracker Inner Tracker
T stations: Outer Tracker 3 stations, each made up of Kapton/Al straws glued together to form modules 4 double-layers (0°,+5°) and (-5°,0°) Ar/CF 4 /CO 2 modules 64-cells wide modules only ~0.7% of 1 X 0 : “light” panel (Rohacell 5 mm core with carbon skins) “light” straws Installation in UX85 November ’06 Commissioning starting December ‘06
T stations: Inner Tracker Silicon strip detectors close to beam pipe, in region of high occupancy: only 2% of area, but 20% of tracks arranged in boxes around beam pipe 410 µ m thick for two-sensor ladders 0.4 m 1.2 m Same sensors as Trigger Tracker Strip length 11, 22 cm, pitch 198 µ Four layers (0°, +5°, -5°, 0°) 320 µ m thick Cooled -5 °C Radiation ≤ 9×10 12 n eq /cm²/10 years for single sensors Installation in UX85 in June ‘06
Ring Imaging CHerenkov Three radiators in two detectors to give π -K separation from 2-100 GeV RICH2 RICH1 Aerogel + C 4 F 10 CF4 Θ 25 to 250 mrad Θ 15 to 100 mrad V p 2 to 60 GeV/c 120 mrad H p 17 to 100 GeV/c 200k channels 295k channels
Novel photon detectors: Hybrid Photon Detectors ~500 tubes, each with a 32x32 pixel sensor array Pixels size (500x500 µ m 2 ) Operated at 20 kV Test beam image Pixels 3000 30 2500 25 20 2000 15 1500 ~150 HPD’s already in hand! 1000 10 Production at a rate ~30 HPD /month… 5 500 0 0 0 5 10 15 20 25 30 Pixels
RICH1 combines the use of aerogel n = 1.03 and C 4 F 10 n = 1.0014 radiators for low momentum particles 7 x 14 HPD array Light weight spherical mirrors High clarity aerogel Glass plane mirrors outside the acceptance Quartz windows to HPD material budget ~7.5% X 0 Switched from Be to C spherical mirrors, quite recently! New design tested April ’06; production expected < end ’06. RICH-1 installation completed ~ March 2007.
High clarity aerogel was developed with a Novosibirsk group … now in production!
Magnetic shielding of RICH1 now installed Magnetic measurements in the HPD plane show residual field of less than 25 Gauss
RICH2 uses CF4 gas radiator for high p particles (n=1.0005) Flat mirror Spherical Mirror Support Structure 7 m Central pipe Photon funnel Shielding Gas vessel: 100 m 3
In position 11.19.2005 Mirrors alignment ~150 µ rad ~100 µ rad mirror movement cf. RICH-2 Cherenkov angle resolution ~ 700 µ rad! RICH-2 completed end 2006
Calorimeter system SPD/PS HCAL SPD/PS ECAL 2 planes of Scintillating Pads + 2 X 0 Pb (1.5 cm); 0.1 λ I ECAL Pb – scintillator Shashlik calorimeter, 25 X 0 ; 1.1 λ I HCAL Fe – scintillator tile calorimeter, 5.6 λ I 19k channels, R/O by WLS fibres to PM or MaPMT’s
Pre-shower SPD / PS 2 scintillator pad planes on either side of a Pb absorber Inner Middle Outer Modules Moving cable trays 4x4 cm 2 6x6 cm 2 12x12cm 2 support structure 4 super modules per half detector VFE + MAPMT ECAL MAPMT MAPMT+ VFE R/O Clear cables fibers 16 Super modules x (2 x 13 modules) 2 x 5952 channels SPD PS SPD PS particles
PS/SPD installation has started… …the Pb modules are in place! Detector installation April to ~September ‘06
Electromagnetic (shashlik) calorimeter Two retrievable halves 3312 modules, 25 X 0 Pb σ E / E = 10% / √ E ⊕ 1% Electron. platform modules Beam plug Chariot stacked: ~ 6 m high positioning agrees to specifications to <1mm!
In place since June ’05… Commissioning 6000 ch.with LED monitoring going on!
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