LHC b COMMISSIONING and operation - PowerPoint PPT Presentation

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Dirk Wiedner- On behalf of the LHCb CollaborationLHCb COMMISSIONINGand operation

Physics at the LHC 2010

LHCb Commissioning

CALORIMETERS

Trackers

VErtex LOcator

MAGNET

MUON Detector

RICHes

Outline

HARDWARE installation

The LHCb Experiment
Commissioning before Beam
pp collisions 2009/10
Conclusions

TRACKER detectors

Dirk Wiedner on behalf of LHCb

LHCb Detector

pp Collision December 2009

BEAM2

BEAM1

[zy]

[zx]

Muon

Calorimeters

(ECAL, HCAL)

MAGNET

4 Tm

RICH2

Tracker

(IT,OT)

Acceptance:

15‐250 mrad (V)

15‐300 mrad (H)

 1.9 < η < 4.9

Vertex

(VELO)

RICH1

p

Tracker Turicensis

(TT)

p

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 vertexing

Up to 2 kHz output

Detector Calibration: Commissioning Steps

WITHOUT Beam

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-detectors

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 Beam

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

Beam-gas interactions

WITH Collisions

450 GeV fills (2009)

3.5 TeV fills (2010)

2008 cosmics data

OUTER TRACKER

MUON

CALORIMETERS

Proton-proton collisions

Velo

Velo sensors all powered

With 450 GeV beams we could not fully close the Velo

. . . but we see where the beams are

Velo

Velo closed for the first time on 1. April

Closing procedure now takes routinely < 15 minutes

Stability in (X; Y ; Z) : (10; 4; 10) μm

PV resolution for track multiplicity of 25

x: ~16 μm

y: ~15 μm

z: ~90 μm

Silicon trackers

TT and IT fully operational

Signal to noise ratio as expected

Alignment ongoing

Residual width is 65μm

See Tracking and alignment in LHCb by Florin MACIUC

Outer tracker

Drift tubes with TDC

Fully operational

Time and space alignment on a good track

Resolution 276 μm

Drift-time space relation determined

Tracking  Λ

~65 μb-1

See Tracking and alignment in LHCb by Florin MACIUC

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 ± 0.15MeV/c2

M(ΛPDG) =1115.68 MeV/c2

RICHes

~65 mμb-1

Preliminary

RICH1

See LHCb particle ID by Philip XING

Kaon ring

Preliminary

RICH2

Kaon ring

With

RICHes

PID!

Beam-Beam December 2009

RICH (Ring Imaging CHerenkov)

allow K-π identification from ~ 2 to 100 GeV

Particle IDentification with RICHes

orange points: photon hits
Continuous lines: expected distribution for each particle hypothesis

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/c2agreement with the PDG value
σ= (6.06 ± 0.03) MeV/c2
π0 can be routinely monitored on-line

π0

Muon

CALORIMETERs

TRACKERs

Beam-Beam @ 3.5 TeV 2010

See J/Psi results from LHCb by Julien COGAN

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

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

MUON

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

LHC State

LHCb State

Handshake

HV/LV State

VELO Motion Control

Coming to a screen near you!

Fill sequence for physics fill in LHCb:

NO_BEAM

INJECTION

RAMP

PHYS_ADJUST

PHYSICS

DUMP

End Of Fill

Detector and Run Control

LHCb PVSS Global Console

Run the LHCb detector as a whole from one console

All sub-detectors included and operational
Detector readout with HLT1 selection
Data storage at nominal 2 kHz

Detector operated with a unified control software

PVSS to control HW and SW processes

LHCb Control Room

Data Quality

Data manager

Alarms and errors

Channel maps

Online reconstruction

Trigger control plots

Problem data base

Data quality shift

Express stream

Reconstruction

Data quality group

Stripping of all physics runs

Categorization of runs

Ks

Luminosity

So far 14 nbarn-1

Luminosity will be measured at LHCb with beam gas

LHCb (In-) Efficiency

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…

J/y from D or B
mixing measurements in the D sector
search for CPV
Bs m m ; fs from Bs J/y f
rare decays (D0mm) in the charm sector
And more: CKM-γ, …

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

730 members

15 countries

54 institutes

LHCb collaboration

Thanks!

730 members

15 countries

54 institutes

LHCb collaboration

Backup

Trigger

Level0 hardware trigger 40 MHz  1 MHz

~ 12 MHz visible interaction @ 2•1032 cm-2s-1
Search for high pT and ET candidates

e, γ, μ, hadron

Pile‐up veto

High Level Trigger 1 MHz  2 kHz

Software trigger
HLT1 1MHz  30 kHz

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

HLT2 30 kHz  2kHz

Full detector information
Inclusive and exclusive selection

LHCb Experiment

bb-bar production along the beam axis

Single-arm forward spectrometer dedicated to study b physics

bb-bar pairs produced with a high boost are highly forward or backward

2009 run conditions(s1/2 = 900 GeV)

Integrated luminosity ~ 7 μb-1

Expected conditions next run 2010/11(s1/2 = 7 TeV)

Expected integrated luminosity ~1 fb-1 in 12-18 months

Nominal Conditions (s1/2 = 14 TeV; L = 2 1032 cm-2 s-1)

Integrated luminosity: 2 fb1/107s

→ ~1012 bbbar pairs per year

Large b cross section ~500 b, about 0.6% of total

Many B, D mesons to study

High background rate

Detector requirements

Highly selective trigger
Good particle identification
Good vertex reconstruction

b

θb

_

b

θb

b

_

LHCb Detector

b

BEAM2

BEAM1

Commissioning with Cosmics

Muon raw hits acquired with the Calorimeter Trigger

 Muon and Calorimeter are in time for FORWARD tracks

M1

Dedicated Level0 trigger selection

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

Calorimeter Trigger

Higher Voltage to see MIP  ~ 10 Hz rate

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!

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)

M2

M3

M4

M5

t (ns)

BACKWARD: not aligned

FORWARD: Time Aligned!



TED run: spatial alignment

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

Relative Alignment VELO –Tracker Turicensis (TT)

expected uncertainty VELO-TT extrapolation: 300 μm
hit residual observed in TT: 500 μm
offset: 150-300 μm

Inner Tracker (IT) alignment ~ 15μm

TT

BEAM2

VELO

IT

Inner Tracker (IT)

BEAM2

Single TED shot

[mm]

Residual for relative Alignment VELO -Tracker Turicensis (TT)

Splash from Beam1

CALORIMETER

 Level0 trigger in nominal condition commissioned with BEAM1!!

 Acquired 5 consecutive bunch crossing centered on the trigger event

Beam1 on the Target Collimator Tertiary (TCTh)

Beam1: correct direction

Looking for Halo and splash events

Statistics to better align inner regions!

OUTER TRAKER

BEAM1

MUON

September 2008

time

+ 25ns

-50 ns

-25 ns

0 ns

+ 50ns

Readout of 5 bunch crossing centered on the trigger event

Beam – Gas interactions

FORWARD

BACKWARD

Beam-Empty bunch crossing:

~ 1 M interaction between beam and the residual gas in beam pipe

VErtex LOcator (VELO) reconstructs the interaction beam – gas

Retractable detector halves

open during injection (30 mm per side)
closed in stable beam condition (Ebeam > 2 TeV)

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

VErtex LOcator

21 stations of Silicon strip detector

Beam – gas interactions

BEAM1

BEAM2

Beam - Gas [XZ] Plane; Crossing Angle

Blue: beam1 – empty

Red: empty - beam2

Green: beam1- beam2 vertex

x (mm)

VELO reconstructs the beams crossing angle using beam-gas interactions
Impact of LHCb dipole magnet

beams cross at 2 mrad angle in [xz] plane as expected at the full magnetic field @ 450 GeV

z (m)

Beam - Gas [YZ] Plane

Commissioning of DAQ chain

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

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

Commissioning of:

run control

run HLT;
exercise control/configuration

HLT processing
online reconstruction and monitoring

Histograms relevant to understand problems

data storage; data quality

Procedure to give the green light
interaction with the GRID

Injector

DAQ network

FEST data flow

Data Acquisition Boards

LHCb detector data flow

High Level Trigger Farm

ONLINE and OFFLINE data Monitoring and Processing

1.9 kHz achieved steadily

LHCb clock phase

LHCb clock to LHC beam phase

temperature dependant

Seasonal and daily time walk

Beam pickup monitor phase measurement

Correction if drift >500ps

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