1. LHCb Status and Prospects Doris Eckstein (CERN) on behalf of the LHCb Collaboration 3rd International Conference on Flavor Physics Chungli, Taiwan, 3-8 October 2005
Introduction
Status and Performance of Detector
Physics Prospects - Examples

2. Introduction LHCb experiment to study CP violation in B-hadron decays
LHC: 14TeV
full spectrum of B-hadrons produced
B-cross-section large ~500mb
Interactions/crossing
Pile-up at high luminosity: choose 2x1032 cm-2 s-1
most events have single interactions
1012 b-hadrons per nominal year of data taking (2 fb-1)
LHCb: forward spectrometer
15-250mrad acceptance
8 October 2005
Doris Eckstein,
ICFP2005

3. Introduction cont’d LHCb: study CP violation look for New Physics
rare B decays
Need:
efficient trigger on leptons and hadrons
efficient particle ID for flavour tagging and background rejection
good proper time resolution for time dependent measurements of Bs decays
good B mass reconstruction for background rejection
8 October 2005
Doris Eckstein,
ICFP2005

4. Introduction - LHCb detector
Kinematics
Magnet + Trackers
Calorimeters
Particle ID
RICH1 and RICH2
Calorimeters
Muon system
Vertex
Reconstruction
VELO
Tracking system
VELO
Trigger Tracker
Inner/Outer Tracker p
250 mrad
10 mrad
8 October 2005
Doris Eckstein,
ICFP2005

5. Detector Status - VELO Downstream Interaction region 42mm 8mm ~1m
Silicon microstrip sensors
42 modules around interaction region
R-F geometry
Strip pitch varies from 40mm to 100mm
Sensors close to beam (8 mm)
Beetle FE chip
VELO hybrid
Module production starting
8 October 2005
Doris Eckstein,
ICFP2005

6. Detector Status - VELO Ensure high resolution
 short extrapolation distance
 small multiple scattering
 Sensors are at 8 mm from beam
 Sensors in secondary vacuum
Roman Pots
Mechanics to allow for retraction
Vacuum Vessel and stand manufactured.
Mechanics to move VELO ready.
8 October 2005
Doris Eckstein,
ICFP2005

7. Detector Performance - Vertexing
dIP = 14mm+35mm/pT
Impact parameter resolution
proper time t=lm/p
Proper time resolution is dominated by B vertex resolution
Bs→Dsp
Impact parameter resolution crucial for proper time resolution
~40 fs for most channels
8 October 2005
Doris Eckstein,
ICFP2005

8. Detector Status - Magnet
∫Bdl = 4 Tm
Warm dipole magnet (Al), Fe yoke = 1600 t
Regularly reverse field to control systematics
Installed in 2004
Field mapping ongoing
8 October 2005
Doris Eckstein,
ICFP2005

9. Detector Status – Tracker
Outer Tracker
Inner Tracker for
Region of high occupancy cm
T1, T2, T3 made of
Outer Tracker and
Inner Tracker
Trigger Tracker
Measurement in fringe field of magnet
Covers full detector acceptance
Provide pt for Trigger (together with VELO)
2*2 layers
Silicon microstrip sensors
500mm thickness
~200mm readout pitch
Production started
8 October 2005
Doris Eckstein,
ICFP2005

10. Detector Status – Tracker
Tracking behind the Magnet – IT and OT
Inner Tracker:
only 2% of area, but 20% of tracks
 Silicon microstrip sensors
11 cm strips, ~200mm pitch
Outer Tracker:
3 stations
each made up of 4 double-layers of Kapton/Al straw tubes
glued together to form modules
two-sensor ladders:
410 mm thickness
Single sensors:
320 mm thickness
Modules in production
Module production close to completion
8 October 2005
Doris Eckstein,
ICFP2005

11. blue = reconstructed tracks
red = detected hits
blue = reconstructed tracks
VELO TT
T1 T2 T3
Detector Performance – Tracking
tracks passing through full spectrometer:
e ~ 95%, a few percent of ghost tracks
Momentum resolution Dp/p ~ 0.4%
Mass resolution BsDsp+
Typical sm~15 MeV
8 October 2005
Doris Eckstein,
ICFP2005

12. Detector Status – RICHes
For hadron ID
Efficient p/K separation up to 100 GeV
Aerogel
C4F10 gas
CF4 gas
RICH2:
High momentum tracks
CF4: ~100 GeV
RICH1:
Low momentum tracks
Aerogel: 2 - ~10 GeV
C4F10: ~60 GeV
5cm Aerogel
n=1.030
8 October 2005
Doris Eckstein,
ICFP2005

13. Detector Status – RICHes
Novel photon detectors: Hybrid Photon Detectors
 Si pixel detectors encapsulated in photo-tube
~ 500 tubes, each with ~1000 pixels
Production underway
HPD tubes
RICH2 ready for transportation
HPDs in production
RICH1 in production
Outside
RICH2 Spherical mirrors aligned to 50mrad
8 October 2005
Doris Eckstein,
ICFP2005

14. Detector Status – Calorimeters
Scintillating Pad Detector/PreShower
2.5 X0 Pb between 2 Scintillator planes
size corresponds to size of ECAL pads
in production
Hadronic Calorimeter (HCAL)
Fe/Scintillator tile calorimeter, 5.6 lI
Granularity varies transversally 13x13 and 26x26cm
SPD/PS
HCAL
HCAL
ECAL
installed, commissioning starts
8 October 2005
Doris Eckstein,
ICFP2005

15. Detector Status – Calorimeters
Electromagnetic Calorimeter (ECAL)
Pb-Scintillator Shashlik, 25 X0
granularity varies transversally from 1 to 3 Rm
sE/E = 10% /E  1% resolution from testbeam
installed
Comissioning started
8 October 2005
Doris Eckstein,
ICFP2005

16. Detector Status – Muon System
MWPC’s
Triple-GEM in inner part of M1 (highest rate region)
Projective pad geometry (used in Trigger)
Muon-Identification
Efficiency ~95% for <1% pion misidentification
MWPC’s in production
GEM production will start soon
calorimeters
8 October 2005
Doris Eckstein,
ICFP2005

17. Detector Performance – Particle ID
K/p separation by RICH
Pion id efficiency ~97%
Pion misid ~3%
Kaon id efficiency ~88%
Kaon misid ~12%
Signal
Background
Large rings: aerogel
Small rings: C4F10
Lepton ID by Calorimeters and
Muon System:
<e(mm)> = 94%
<e ( m)> = 1%
<e(ee )> = 81%
<e( e)> = 1%
8 October 2005
Doris Eckstein,
ICFP2005

18. Trigger 40 MHz 1 MHz Recent change:L0
High pt hadron, lepton, g
Flag multiple interactions, busy events
Hardware (custom boards), latency 4ms
Calo, Muon, Pileup, SPD L1
Combined high pt, high IP
Software (PC farm), partial event information,decision in 1ms
VELO, TT
HLT
Inclusive and exclusive
Software (PC farm), complete event, 10ms
Full information from detector
On tape
40 MHz
1 MHz
40 kHz
2 kHz
L0, L1
L0×L1
Recent change:
Full detector information read out at 1 MHz
Zero suppressed
Combined software trigger
8 October 2005
Doris Eckstein,
ICFP2005

19. Physics Prospects – Baseline Measurements
Bs mixing (new physics effects in box diagrams)
Dms from Bs→Dsp
fs and DGs from Bs→J/yf
CKM angles from different processes to over-constrain unitary triangle
sin(2b) from Bd → J/yKs
Important check/comparison with B-factories
g from various channels
different sensitivity to new physics
g from Bs → DsK time dependent asymmetries
g from B → pp, Bs → KK time dependent asymmetries
g from B → D0K*0 decay rates
a from Bd → rp
rare B decays (b → s processes, NP now yet well constrained)
Bs → mm down to SM BR
Bd → K*mm : measure forward-backward asymmetry
8 October 2005
Doris Eckstein,
ICFP2005

20. Physics Prospects – Dms
Decay time resolution
Bs  Ds-p+
Proper time resolution ~ 40 fs
S/B~3
80k events/year
Dms=25ps-1
1 year of LHCb data
Statistical uncertainty on amplitude of Bs oscillation as function of Dms
5σ measurement in 1 year of running for Δms up to 68 ps-1
(far beyond Standard Model expectation Δms < 26 ps-1)
oscillations clearly observed with 1 year of
data taking!
Once oscillations are established, determine Δms with σ(Δms) ~ 0.01ps-1 stat.
8 October 2005
Doris Eckstein,
ICFP2005

21. Physics Prospects – g from Bs→DsKu b c Bs
Ds- K+
Interference of tree diagrams yields phase of g+fs
fit four time dependant decay rates:
Bs → Ds-/+ K+/-
fs measured through Bs→J/yf
Free of new physics contributions in penguin diagrams
Measured g not affected by new physics in Bs mixing
Discrepancy with indirect g from CKM fit will signify new physics in mixing
Sensitivity after 1 year:
Dms
20ps-1
25ps-1
30ps-1
s(g)
14.2
16.2
18.3
8 October 2005
Doris Eckstein,
ICFP2005

22. Physics Prospects – g from B→hh
Bd ->pp 25k events/year
Bs -> KK 37k events/year
Bd/s
/K
/K
Bd/s
time dependent asymmetries for Bd→pp and Bs→KK
ACP(t) = Adir cos(Dm t) + Amix sin(Dm t)
Parameters:
Mixing phases fd or fs
 through Bd→J/yKs and Bs→J/yf
Penguin/Tree=deiq
U-spin symmetry: dpp=dKK, qpp=qKK
4 observables, 3 unknowns: solve for g
Dms=20ps-1, DGs/Gs=0.1, g=65o, q=160o,
d=0.3, Fs=-0.04
One year: s(g) ~ 5+ uncertainty from U-spin symmetry breaking
Sensitive to new physics in penguin
8 October 2005
Doris Eckstein,
ICFP2005

23. Summary
The detector is designed for precise vertexing and tracking and excellent particle identification.
LHCb has a high performance trigger dedicated to B physics.
LHCb will extend the B physics results from B-factories and Tevatron due to the high statistics expected and the full spectrum of B-hadrons available.
LHCb spectrometer construction is progressing well.
Overall commissioning will start end of 2006.
We are looking forward to first data in 2007!
8 October 2005
Doris Eckstein,
ICFP2005