Status of the LHCb experiment

Andrei Golutvin ( Imperial & CERN & ITEP )on behalf of the LHCb Collaboration

Outline:

Introduction Detector Subsystems Trigger/Online/Computing First Look at the data Cost and funding issues Collaboration matters Preparation for LHCb upgrade Physics goals in 2010

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Commissioning of LHCb with data was the main activity since last RRB

Detector is time aligned to optimal working point within 1–2 ns. Data taken with and without magnetic field for position alignment

A total of 300k collision events at 900 GeV recorded in 2009. Overall operation went very smoothly. Due to beam optics Vertex Detector (VELO) modules can approach only ±15 mm from the beam. The VELO powering and closing procedures have been optimized and commissioned In 2010, from first collisions onwards, LHCb is taking successfully data at 7 TeV with high efficiency LHCb is in excellent shape for the Physics Run in 2010-2011

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Brief Summary

LHCb Collaboration

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730 members15 countries54 intitutes

VErtex LOcator (CH,DE,GB,NL) 2×21 pairs of Si sensors arranged in 2 halves; each pair consists of one sensor with R-

and one sensor with -strips

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99.3% of channels operational– For first collisions at 900 GeV VELO was operated in a safe

mode utilizing an “incremental” powering scheme. VELO was

powered in its open position and then each half moved to within 15 mm of the nominal physics position (full closure possible only above 2 TeV /beam)

– Primary vertex distributions from

both beam-beam and beam-gas

events

– The module alignment is stable

within 4 μm. Two halves relative

position is aligned to better

than 30 μm, as evaluated with

2009 and 2010 data

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When running at 3.5 TeV per beam VELO has beensuccessfully closed

During closing procedure

• The distance between two VELO halves has been measured using reconstructed primary vertices at each step of the 1st closing with beam

• Closing procedure works well ( takes ~ 15 min now ) Will be further improved !

Reconstructed distance between VELOhalves as a function of time during 1st closure

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Status of VELO replacement• All 42 hybrid replacement modules have been built and tested Burn in programme in Q2 2010

• The replacement mechanics is expected to be completed by October 2010

• Complete VELO replacement halves are planned to be ready for the LHC start in 2011

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Outer Tracker – OT (CERN,CF,CN,DE,NL,PL)Three stations with each 4 stereo layers of straw tubes 5 mm diameter and 5m length; 55k channels

OT

CaloMuon

• Detector is 100 % efficient and running with low noise at the nominal threshold. All Front-End spares are available

• In order to improve aging behavior a 1.5% fraction of O2 has been added to the gas mixture. Aging tests in situ show mitigating effect of O2 and a general improvement with flushing time. Furthermore the possibility of curing gain losses in situ by means of HV training procedure has been demonstrated

One of the first LHCb collision events @ 3.5 TeV per beamregistered on March 30

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Drift-time space relation (R(t))

R(t) from test beam R(t) from fit to proton data

R

Plateau efficiency 98.7 %

R [mm]

Hit residuals:

Data/MC differences due to missing module alignment

straw tube

OT performance:

Without O2 @ 450 GeVWith O2 @ 3.5 TeV

No effect caused by addition of O2

Cell efficiency profile:Efficiency vs. distance in mono layer plane

ST: Tracker Turicensis & Inner Tracker(CERN,CH,DE,ES,UA)

TT covers area of 1.41.2 m2; 4 stereo layers with ladders consisting of 3 or 4 chained Si- sensors with strip pitch 183 micron; 143k channelsIT: 3 stations with 4 boxes each arranged around beam pipe; each box has 4 stereo layers x-u-v-x, modules with one or two chained Si-sensors; strip pitch 198 micron; 130k channels

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• Both TT and IT run smoothly and without problems (> 99.5% of TT channels and 99% of IT channels are operational)

• Significant progress in improving stability and reliability of the control and monitoring software

• The problem of breaking bonds on the TT hybrids has stabilized. No new broken bonds since May 2009. New hybrids are being ordered and the nine affected modules will be repaired

• Internal alignment of IT has been verified with beam and a global alignment relative to the other tracking components performed

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TT and IT performanceσ = 77.3µm

unbiased residual σ~72μm

TTUnbiased TT residuals is still broader thanexpected in MC (49 μm). Further improvementwill be achieved soon

IT tracks and efficiencies (alignment fixed from TED data)

IT• Unbiased residuals (2009 data) still show room for improvement (expect ~ 50 μm)

• Efficiencies O(98%)

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Demonstration of tracking performance with reconstructed particles

Ξ from ~ 65 µb-1

Λ from ~ 65 µb-1KS from ~ 65 µb-1

RICH (CERN,CF,GB,IT)RICH1 and RICH2 with 3 radiators covers momentum range 2-100 GeV; RICH1: 5cm aerogel with n=1.03 & 4m3 C4F10 with n=1.0014; RICH2: 100m3 CF4 with n=1.0005;

~500 HPD to readout

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Both RICH1 and RICH2 take data with great success

• RICH2 was fully aligned. For RICH1 more data are required to align the mirrors in the outer region from where aerogel rings are reflected. Also some indication that the poor resolution for the aerogel rings is due to low photon yield.

• Evolution of each HPD lifetime using ion feedback is continuously monitored. In March those tubes predicted to glow in 2010 have been replaced with refurbished ones. The repair process is proceeding regularly and the extracted tubes are being sent to PHOTONIS.

• Satisfactory stability of HV system and gas system

• PID performance has been calibrated using kinematically reconstructed Ks mesons and Λ hyperons.

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after alignment

momentum spectrum

before alignment

RICH 1LHCb data(preliminary)

Kaon ring

RICH 2LHCb data(preliminary)

Kaon ring

Orange points photon hits Continuous lines expected distribution for each

particle hypothesis (proton below threshold)

PID with RICH

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Demonstration of RICH PID performance with reconstructed particles

Φ from ~ 65 µb-1

K* from ~ 65 µb-1

Calorimeters (CERN,CF,ES,FR,RO,RU,UA) PS/SPD: 12k scint. tiles readout by WLS; ECAL:

6k shashlik cells; HCAL: TILE Calo, 1.5k channels

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The four calorimeter systems operate very effectively providing the principle trigger for LHCb

• Initial time alignment has been significantly improved. The current inter-cell time alignment is 1 ns for HCAL/ECAL and 2 ns for PS/SPD

• Energy calibration is being gradually improved using collected data. Inter-calibration at the start-up was close to 9% for ECAL, <4% for HCAL and ~15% for PS

• The reconstructed masses and widths of the 0 andsignals agree well with expectations. In order to reach ~1% calibration accuracy for ECAL and PS one needs ~50 M events.

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π0

<m> = (135.0±0.6) MeV/c2

σ = (10.9±0.7) MeV/c2

Et(γ)> 300 MeV; Et(di-γ)> 2 GeV

η

<m> = (547±5) MeV/c2

σ = (24±3) MeV/c2

N(πº)=849±36N(η)=146±32R(η/ πº)=17.2±3.8 %

N(πº)=719±31N(η)=163±27R(η/ πº)=22.7±3.8 %

2009 data Monte Carlo

2009 data 2009 data

MeV/c^2

Et(γ)> 500 MeV; Et(di-γ)> 2 GeV Et(γ)> 500 MeV; Et(di-γ)> 2 GeV

Et(γ)> 300 MeV; Et(di-γ)> 2 GeV

Demonstration of CALO performance with reconstructed particles

Muon (CERN,CF,IT,RU)Arranged in 5 SuperLayers; M1 consists of 12 double triple GEM

chambers and 264 MWPC’s; M2-M5 consists of 1104 MWPCs

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• The Muon system operates successfully, both the efficiency and the noise level are in perfect agreement with expectations from the test beam

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• Muon detector hardware performs very well:

- Only ~0.1% chamber gaps showed some HV problems - <0.1% dead readout channels - Negligible number of noisy channels

• Time alignment in perfect agreement with expectations

• Space alignment: analysis of collision data taken in 2009 confirmed ~7-8 mm shift in X of M4 A-side that was seen with cosmics M4 position was corrected in January 2010

• Stability of HV modules is of some concern. Full review of the HV control system has been made and some hardware modifications have been applied to the CAEN power supply system to achieve more reliable operation

MUON performance

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Strategy for trigger settings in 2010

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Few fills at injection energy 450 GeV, 2-4 bunches 5·1010 p colliding,

β * =10 => rate ~(few) 100 HzRamp in energy 3.5 TeV, 2 bunches 1·1010 p colliding,

β*=10 => rate ~100 Hz

Squeeze of β* 3.5 TeV, 2 bunches 1·1010 p colliding, β* = 2 => rate ~500 HzIncreased bunch charge 3.5 TeV, 2 bunches 5·1010 p colliding,

β*=2 => rate ~10 kHz

Increasing number of bunches 3.5 TeV, 19 bunches 5·1010 p colliding,

β*=2 => rate ~100 kHz

mbias triggers based on Level 0 objects: muon pT, hadron pT, Pile-Up System

L0 and HLT optimized for prompt Charm and Beauty

+ (mbias & random triggers) downscaled

Optimized for Beauty Physics

Prompt charm efficiency increased by more than a factor 4 w.r.t. design settings without loss in b-physics

Evo

lutio

n of

lum

inos

ity in

firs

t few

mon

ths

When moving to crossing angle and 50 ns bunch spacing we expect L~1-

2·1032 cm-2s-1 with ~200 pb-1 in 2010 and ~1 fb-1 in 2011

(~1/2 of a nominal year for LHCb)

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Online & Computing

• Data monitoring and online reconstruction are commissioned and in regular use Some minor problems with the switches of the read-out network, which are addressed by the manufacturer with high priority

• Completion of the HLT farm to its full capacity is foreseen towards the end of 2010 depending on the LHC luminosity progress

• Data processing chain works well. New data are distributed to the LHCb Tier1s, fully reconstructed on the Grid and made available for analysis within a few hours.

• Three reprocessing done so far on the Grid, each taking less than one day

• Simulation campaign to prepare the 2010-2011 analyses of data at 3.5 TeV started

• Some concern with Tier1s stability in particular regarding Storage and Data Access CERN site busy with user analysis

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D0→Kπ from ~110 µb-1

D+ →Kππ from ~110 µb-1

Towards LHCb physics programme

First D mesons havebeen reconstructed !!!

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J/ψ from ~160 µb-1

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B+→J/ψK+ candidate: global view(muons are magenta, kaon is red)

4 J/ candidates have non-zero proper time as expected for production in B decays BJ/

>25 separation between primary and secondary vertices

First candidate for reconstructed B meson

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Primary vertex

B decay vertex+

-

K+

J/ψ

B+

[x 0.2mm]

[mm]

YZ Projection

Tracks from primary vertex

B→J/ψK candidate: YZ vertex zoom

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Cost and Funding

Collaboration Matters• Two new institutes accepted as Technical Associates: - Catholic University of Rio de Janeiro, Brazil - Tier-1 centre CCIN2P3, Lyon, France

• Guy Wilkinson (Oxford) is the Physics Coordinator for a term of 1 year as from January 1, 2010 • Rolf Lindner has been appointed as the Technical Coordinator for a term of 3 years starting from July 1, 2010

• Marco Cattaneo (CERN) has been appointed as the Computing Project Leader for 2 years starting from January 1, 2010• Chris Parkes (Glasgow) has been appointed as the Vertex Detector Project Leader for 2 years starting from June 15, 2010

• Overall situation is healthy; no cash flow problem foreseen

• VELO replacement financing mechanism works well

• Prepare for important interventions on sub-detectors and infrastructure during long shutdown in 2012

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LHCb Upgrade activities

A Letter of Intent for the LHCb upgrade is under preparation

The strongest part of the LHCb physics case is the flexibility to be preparedfor the exploration of New Physics

Staged approach:

First stage – Full software trigger

- Upgrade to 40 MHz readout keeping sub-detectors unchanged wherever is possible

- Construct NEW VELO

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Expected B-physics reach in 2010-2011

Sensitive probe for MSSM with large tanβ: Br (BSμ+μ-) ~ tanβ6 / MA

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Large (non-SM) phase favoured by D0 and CDF analysis:Φs [ −1.47 ; −0.29 ] [ −2.85 ; −1.65 ∪] (90% CL range)

Assume ~200 pb-1 in 2010 and ~1 fb-1 in 2011

2010

2011

Exclusion limit @ 90% C.L.

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Conclusion I LHCb is successfully taking data with high efficiency !!!

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LHCb operation over 30/3-13/4

17%

69%

8%1% 5%

Tech Velo closed Velo open DAQ Others

On the ~82 hours of collision delivered

-Technic program completed at 95%

- 98% DAQ efficiency -95% detector efficiency

-Velo closing efficiency 94% - Mostly in beginning - Long fill help

In 2010 we have so far recorder ~14M collisions at √s = 7 TeV

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First data are being used for calibration of the detector and trigger in particular. - First results of low Pt physics are available at LHC energies

- Some high class measurements in the charm sector may be possible with 50 pb-1. Charm resonances have been reconstructed.

With ~ 200 pb-1 data sample LHCb will reach Tevatron sensitivity in a few golden channels in the beauty sector

Further consolidation is important prerequisite for efficient long term operation (e.g. R&D on improved reliability

of readout cards in EPFL)

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Conclusion II

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