LHC b COMMISSIONING and operation

Dirk Wiedner- On behalf of the LHCb Collaboration

LHCb COMMISSIONINGand operation

1

Physics at the LHC 2010

https://indico.desy.de/conferenceDisplay.py?confId=1964

LHCb commissioning and operation7 June 2010 Dirk Wiedner on behalf of LHCb 2

LHCb CommissioningOutline The LHCb Experiment Commissioning before

Beam pp collisions 2009/10 Conclusions

HARDWARE installation

MUON Detector

VErtex LOcator MAGNET

RICHes

CA

LO

RIM

ET

ER

S

TRACKER detectors

Trackers


LHCb Detector

Acceptance: 15‐250 mrad (V)15‐300 mrad (H) 1.9 < η < 4.9

p p

MAGNET 4 Tm

[zx]

Vertex(VELO)

Tracker(IT,OT)

Calorimeters(ECAL, HCAL)

MuonRICH2

RICH1

p p

Tracker Turicensis

(TT)

[zy]

BEAM1 BEAM2

pp Collision December 2009


B+ J/Ψ K+


Trigger Strategy

L0 (up to 1 MHz)

Muon trigger

Calorimeter trigger (electron, photon, hadron)

HLT: computer-farm running full reconstruction

L0 confirmation and vertexingUp to 2 kHz output


Detector Calibration: Commissioning Steps

2008 cosmics data

OUTER TRACKER

CALORIMETERS

MUON

WITHOUT Beam1. Test pulse (LED, pulsing systems and radioactive source)

• Calorimeters time aligned ~ 1ns• Each Muon half-station internally aligned ~ 3 ns• No relative time alignment between different sub-

detectors2. Commissioning with Cosmics (started spring 2008)

• Detector acceptance and trigger optimized with respect to the interaction point

• ~ 4 M events collected• Sub-detector relative time alignment

WITH Beam3. LHC injection test (started September 2008)

TED Runs: Beam2 dumped on the injection line beam stopper 350 m downstream LHCb

Particles coming from behind the detector and not centered (8 mrad [H] and 12 mrad [V])

Time alignment between sub-detectors ~1 ns Spatial alignment

4. Beam-gas interactions

WITH Collisions5. 450 GeV fills (2009)6. 3.5 TeV fills (2010)


Proton-proton collisions


Velo sensors all poweredWith 450 GeV beams we could not fully close the Velo. . . but we see where the beams are

Velo


Velo

Velo closed for the first time on 1. AprilClosing procedure now takes routinely < 15 minutesStability in (X; Y ; Z) : (10; 4; 10) μmPV resolution for track multiplicity of 25

x: ~16 μmy: ~15 μmz: ~90 μm


TT and IT fully operational

Signal to noise ratio as expected

Alignment ongoingResidual width is 65μm

Silicon trackers See Tracking and alignment in LHCb by Florin MACIUC

https://indico.desy.de/contributionDisplay.py?contribId=189&sessionId=17&confId=1964


Outer trackerOuter tracker

Drift tubes with TDCFully operationalTime and space alignment on a good trackResolution 276 μmDrift-time space relation determined


Tracking Λ The masses of the reconstructed Λ in agreement with the PDG values Tracking without VELO: tracking detectors were well calibrated at the start-up ! Now using full tracking power, including VELO Tracking in good shape for charm and beauty physics

M(Λ) = 1115.74 ± 0.01 MeV/c2

σ = 2.83 ± 0.15 MeV/c2

M(ΛPDG) =1115.68 MeV/c2

See Tracking and alignment in LHCb by Florin MACIUC

~65 μb-1



RICHes

Beam-Beam December 2009

RICH1

RICH2

Kaon ring

Kaon ring

Preliminary

Preliminary

RICH (Ring Imaging CHerenkov)o allow K-π identification from ~ 2 to 100 GeV

Particle IDentification with RICHeso orange points: photon hitso Continuous lines: expected distribution for

each particle hypothesis

With RICHes

PID!

See LHCb particle ID by Philip XING

~65 mμb-1



Calorimeter• The calorimeters systems work very effectively, providing the

principal trigger at LHCb• Time alignment now 1 ns• PS/SPD calibration using MIPs• ECAL Energy calibration ongoing. Need 50M events to

achieve 1% with π0

<m> = (135.16 ± 0.02) MeV/c2 agreement with the PDG value

σ= (6.06 ± 0.03) MeV/c2

π0 can be routinely monitored on-line

π0


Muon Muon system works very well part of L0 trigger Event with dimuons

Oppositely charged muon candidates from the interaction region

Time resolution in perfect agreement with expectation!

J/Ψ peak from dimuon events 12.8 nbarn -1 of data

Beam-Beam @ 3.5 TeV 2010

TRACKERs

CALORIMETERs

MUON

See J/Psi results from LHCb by Julien COGAN

Results and prospects for dimuon final states at LHCb by Justine SERRANO

J/Ψ




LHC/LHCb operation procedure

Fill sequence for physics fill in LHCb:NO_BEAM

INJECTION

RAMP

PHYS_ADJUST Velo open

PHYSICS Velo closed

DUMP Velo open

End Of Fill


LHC/LHCb operation procedure

Fill sequence for physics fill in LHCb:NO_BEAM

INJECTION

RAMP

PHYS_ADJUST

PHYSICS

DUMP

End Of Fill

VELO Motion Control Coming to a screen near you!

LHC State LHCb State

Handshake

HV/LV State


Detector and Run Control

Run the LHCb detector as a whole from one consoleo All sub-detectors included and operationalo Detector readout with HLT1 selectiono Data storage at nominal 2 kHz

LHCb PVSS Global Console

LHCb Control Room

Detector operated with a unified control softwareo PVSS to control HW and SW

processes


Data Quality

Data managerAlarms and errorsChannel mapsOnline reconstructionTrigger control plotsProblem data base

Data quality shiftExpress streamReconstruction

Data quality groupStripping of all physics runsCategorization of runs

Ks


Luminosity

LHCb (In-) EfficiencySo far 14 nbarn-1

Luminosity will be measured at LHCb with beam gas


Conclusions LHCb detector is in good shape! Cosmics data have been very useful for the commissioning of LHCb detector First collisions were used to conclude commissioning

higher statistics are now used to fine tune calibrations Intense physics program to fulfill (integrated luminosity ~1 fb-1 in 12-18 months) with many

channels to look at…o J/ y from D or Bo mixing measurements in the D sector o search for CPVo Bs m m ; fs from Bs J/ y fo rare decays (D0mm) in the charm sectoro And more: CKM-γ, …

730 members15 countries54 institutes

LHCb collaboration

See also:• Status of and news from LHCb by Andrei GOLUTVIN (Imperial College)• Tracking and alignment in LHCb by Florin MACIUC • LHCb particle ID by Philip XING• LHCb first physics results by Olivier SCHNEIDER• Minimum bias physics at LHCb by Walter BONIVENTO • Charm physics results and prospects at LHCb by Joerg MARKS • J/Psi results from LHCb by Julien COGAN• Results and prospects for dimuon final states at LHCb by Justine SERRANO• Prospects for CP violation at LHCb by Geraldine CONTI











Thanks!

730 members15 countries54 institutes

LHCb collaboration


Backup


Trigger1. Level0 hardware trigger 40 MHz 1 MHz

o ~ 12 MHz visible interaction @ 2•1032 cm-2s-1

o Search for high pT and ET candidates• e, γ, μ, hadron

o Pile‐up veto

2. High Level Trigger 1 MHz 2 kHzo Software triggero HLT1 1MHz 30 kHz

• Confirms Level0 candidates• Vertex and tracker detectors• Impact parameter and lifetime cuts

o HLT2 30 kHz 2kHz• Full detector information• Inclusive and exclusive selection


LHCb Experimentbb-bar production

along the beam axis

b

_b

θb

b

_b

θb

Single-arm forward spectrometer dedicated to study b physicso bb-bar pairs produced with a high boost are highly forward

or backward

2009 run conditions (s1/2 = 900 GeV)o Integrated luminosity ~ 7 μb-1

Expected conditions next run 2010/11 (s1/2 = 7 TeV)o Expected integrated luminosity ~1 fb-1 in 12-18 months

Nominal Conditions (s1/2 = 14 TeV; L = 2 1032 cm-2 s-1)o Integrated luminosity: 2 fb 1/107 s

→ ~1012 bb bar pairs per yearo Large b cross section ~500 b, about 0.6% of total

Many B, D mesons to study High background rate

Detector requirementso Highly selective triggero Good particle identificationo Good vertex reconstruction

BEAM1

BEAM2LHCb Detector


Commissioning with Cosmics Dedicated Level0 trigger selection

1. Muon Trigger• Nominal coincidence of 5 stations ~ 0 Hz rate• AND of the two last Muon stations 4 Hz rate• Central Muon station alone (M3) 60 Hz rate

2. Calorimeter Trigger• Higher Voltage to see MIP ~ 10 Hz rate

o No Vertex constraints Open a time window of several bunch

crossing centered on the triggered one• Time Alignment Event (TAE)

• Start time alignment between sub-detectors Start commissioning of basic Level0 trigger

building blocks!o Calorimeters and Muon aligned ~ 3 ns for

forward tracks Improvement of Muon Detector internal time

alignment• r.m.s time distribution from 9 ns (first cosmics

2008) to ~ 4 ns (last measurement 2010)

FORWARD: Time Aligned!

BACKWARD: not aligned

t (ns)

M2

M3

M4

M5

M1

Muon raw hits acquired with the Calorimeter Trigger Muon and Calorimeter are in time for FORWARD tracks


VELO, Tracker Turicensis, Inner Tracker detectors start of spatial alignment

TED run: spatial alignment

Residual for relative Alignment VELO -Tracker Turicensis (TT)

IT

TT

VELO

Relative Alignment VELO – Tracker Turicensis (TT)o expected uncertainty VELO-TT

extrapolation: 300 μmo hit residual observed in TT: 500 μmo offset: 150-300 μm

Inner Tracker (IT) alignment ~ 15μm

BEAM2

BEAM2 Inner Tracker (IT)

Single TED shot[mm]


Level0 trigger in nominal condition commissioned with BEAM1!!

Acquired 5 consecutive bunch crossing centered on the trigger event

OUTER TRAKER

CALORIMETER

MUON

Splash from Beam1

-50 ns -25 ns 0 ns + 25ns + 50ns

BEAM1

Beam1 on the Target Collimator Tertiary (TCTh)o Beam1: correct direction

Looking for Halo and splash events Statistics to better align inner

regions!

time

Readout of 5 bunch crossing centered on the trigger event

September 2008


Beam – Gas interactions

BEAM1 - GAS

BEAM2 - GAS

Beam1-Gas 11/2009: Triggered by Calorimeters OR Muon (rate ~ 5Hz)

Beam2-Gas 11/2009: Triggered by VErtex LOcator: backward silicon stations

Beam-Empty bunch crossing:o ~ 1 M interaction between beam and the

residual gas in beam pipe VErtex LOcator (VELO) reconstructs the

interaction beam – gas o Retractable detector halves

• open during injection (30 mm per side)

• closed in stable beam condition (Ebeam > 2 TeV) VErtex LOcator21 stations of Silicon strip detector

FORWARD BACKWARD


Beam – gas interactions VELO reconstructs the beams

crossing angle using beam-gas interactions

Impact of LHCb dipole magnet o beams cross at 2 mrad angle in [xz] plane as

expected at the full magnetic field @ 450 GeV

x (mm)

z (m)

Blue: beam1 – empty

Red: empty - beam2

Green: beam1- beam2 vertex

Beam - Gas [YZ] Plane

BEAM1 BEAM2

Beam - Gas [XZ] Plane; Crossing Angle

BEAM1 BEAM2


High Level Trigger Farm

Data Acquisition Boards

ONLINE and OFFLINE data Monitoring and Processing

Injector

FE

ST

da

ta flo

w

LHCb detector data flow

DAQ network

Commissioning of DAQ chain

Commissioning of:o run control

• run HLT;• exercise control/configuration

o HLT processingo online reconstruction and

monitoring• Histograms relevant to understand

problems

o data storage; data quality • Procedure to give the green light• interaction with the GRID

1.9 kHz achieved steadily

FEST (Full Experiment System Test) Raw-Monte Carlo events injected into the DAQ chain

o inject @ 2kHz at the High Level Trigger input (limited by Monte Carlo injection)o generated 100 M minimum bias (14 hours)


LHCb clock phase

LHCb clock to LHC beam phase temperature dependant

Seasonal and daily time walk

Beam pickup monitor phase measurementCorrection if drift >500ps

-2.50-2.00-1.50-1.00-0.500.000.50

[ns]

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LHC b COMMISSIONING and operation