Status of the LHCb experiment
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Transcript of Status of the LHCb experiment
Status of the LHCb experiment
Andrei Golutvin ( Imperial & CERN & ITEP )on behalf of the LHCb Collaboration
Outline:
Introduction Detector Subsystems Trigger/Online/Computing Cost and funding issues Collaboration matters Physics goals in 2010
RRB October 2009 1
2
The installation of LHCb is fully completed, including M1 station
All detector elements are commissioned and ready for data taking Read out at 1 MHz successfully tested
Full Experimental System Test (FEST), which is able to inject MC data to Event Filter Farm, is used for the HLT commissioning Strategy for trigger and subsequent physics analysis of the 2009-2010 Run is prepared LHCb is fully operational for the Physics Run in 2010
RRB October 2009
Brief Summary
LHCb Collaboration
3
700 members15 countries52 intitutes
RRB October 2009
RRB October 2009 4
Beam Pipe (CERN)23 m long beam pipe consisting of 3 Be and 1 stainless steel sections
• The procurement of a replacement beam pipe UX85/3B is underway It is fully budgeted by CERN
• Design of optimized beam pipe supports with reduced material is ongoing
Magnet (CF)Warm dipole magnet with 4 Tm bending power
along the beam axis
• Magnet was powered in July and September 2009 to perform a survey on the support of TT and RICH-1 shielding using CCD cameras. Much improved stability no other intervention on the support structures needed
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
5RRB October 2009
VELO is now ~100% operational
– LV and HV system are operating stable
LV spares situation substantially improved due to delivery of spares from CAEN
– DAQ read out at 1 MHz– Online and offline monitoring finalized – Vacuum and cooling systems fully operational
Until September 2009 the temperature was kept at -5°C.
Lowered to the nominal -30°C for the recent TED RUN (completed Yesterday) in readiness for full data taking
– VELO interlock box ready (including spare)– The build of the VELO replacement continues. ~50% of
modules,
capton cables and vacuum feedthroughs complete
RRB October 2009 6
TI8
LHC
- Transfer line External beam Dump - Shots every 48 seconds - Joint work with TT/IT/ST and SPD - Typical occupancy of 7 clusters/sensor/event
• The procedure to tune the timing tested with data
• Timing accuracy < 2 ns can be achieved with ~ 100 clusters/sensor/step
• Timing is monitored online
VELO experience with TED runs
RRB October 2009 7
Results with 255 tracks: Histogram 2.163
mm( = 0.080 mm)
Milliepede 2.156 mm
The halves were moved by a “secret” amount (450 m).
Results with 852 tracks: Histogram 2.611
mm ( = 0.087 mm)
Milliepede 2.601 mm
Very Preliminary
Very Preliminary
VELO was moved by 445 ± 10 m
Evaluation of the distance between 2 VELO halvesusing TED data
RRB October 2009 8
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
Outer Tracker is ready for data taking
• Installation and test of FE electronics completed
• OT read out at 1.11 MHz
• HV test continued, 99.9% channels ok! Likely a large fraction of remaining 0.1% can be recovered
• The anti-ageing treatment of detector modules at 40°C in situ has been completed. Gas system modified to allow an oxygen admixture if necessary
• Initial time and space alignment within expectations The procedures for further offline improvements give expected results. High level data quality monitoring is being finalized
RRB October 2009 9
- 2 FE boxes show high rate issues- 3 FE boxes (at the edge of acceptance) dismounted
Status of the Front End electronics (9 / 2009)
RRB October 2009 10
without alignment with alignment
T1 T2 T3
OT spatial alignment using cosmics(using drift time information)
Alignment accuracy better than 100 musing only 10k tracks
ST: Trigger Tracker & 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
RRB October 200911
ST is ready for data taking
• After repair work during shutdown 99.7% IT channels and 98.6% TT channels are operational
• Both detectors successfully read out at 1 MHz
• Detailed studies of detector performance using TED data; IT ladders aligned to < 20 m precision
• Remaining concern is the broken bonds appearing on seven TT modules. Four of the effected modules replaced with spares; three left in situ to study the evolution in the pit. Order new hybrids in the next months.
RRB October 200912
Innermost bond row affectedEffect not reproduced in the lab(despite of extensive studiesapplying vibrations & thermalcycling)
Possible causes:
• Initial cracks due to the bonding process, typically occur at first bonds• Loop height (should be > 25%)
RRB October 200913
Three modules left in situ in order to study progress of the problemOrder for new hybrids to be placed
RRB October 200914
ST analysis of TED data
RRB October 200915
• IT ladders aligned to precision of ~14 m
• TT alignment requires better understanding of VELO seeds
• Expect from the analysis of recent TED run:
- Improved quality of VELO-TT & IT-TT tracks - Improved timing
RICH (CERN,CF,GB,IT)RICH1 and RICH2 with 3 radiators covers momentum rRecent highlighange 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
RRB October 200916
Both RICH1 and RICH2 are complete, commissioned and waiting for data
• Recent highlight is the observation of Cherenkov rings from the aerogel and gas ( C4F10 ) radiators using cosmic rays convincing test of the online monitoring and offline reconstruction software.
• Estimate of lifetime is well established process for each HPD. The details of repair process of all degraded tubes agreed with DEP-PHOTONIS. Tubes expected to fail in RICH-2 in 2009/2010 are being replaced (14 HPD available).
• Timing alignment, in particular for RICH-2.
• RICH-1 Magnetic Distortion Monitoring System tested.
• Some HV supplies were showing short saturation glitches. Cause identified by the manufacturer. All HV suppliers repaired. Overall stability is now satisfactory
LHCb RICH1 sees rings with cosmic rays(RICH1 has two radiators: aerogel and gas)
Ratio of the rings radiicorresponds to the ratio of the gas and aerogelrefractive indexes
Aerogel ring
Gas ring
17RRB October 2009
• Excellent Signal/Noise of HPD (only a few out of ~105 active channels were noisy). • Number of detected Cherenkov photons agree with expectations
18RRB October 2009
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
19RRB October 2009
The four calorimeters system SPD/PS/ECAL/HCAL is fully operational
• Much improved stability of the 6000 ECAL channels modified during 2008/2009 shutdown. PMT gain measurements agree within 5% with earlier test measurements ~10% inter-calibration at the start-up
• HCAL is inter-calibrated to <4% using the Cesium source
• All calorimeters are successfully read out at 1 MHz
• SPD/PS/ECAL/HCAL time aligned within 3 ns Further improved using TED data
• Emphasis on ECAL calibration procedures and data quality controls
RRB October 2009 20
Timing inside crate & Front End card
PS / ECAL / HCAL aligned to < 1ns using TED dataFast improvement expected with a few millions events
Improved CALO timing using TED data
RRB October 2009 21
(G(LED) – G(HAM)) / G(LED)
Mean: 2.3%
R.M.S.: 11.4%
Comparison of the ECAL PMT gain measured in situ with previous measurements (@ LAL and Hamamatsu)
PMT gain can be measured in situ using LED calibration system
Taking into account that all moduleshave been measured at cosmics beforethe installation ECAL is inter-calibratedto ~ 10% at the start-up
Several methods to reach 1% levelusing 0 signals have been tested with MC data
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
22RRB October 2009
• The installation of M1 station completed in time by July 7 M1 commissioning is nearly completed; M1 included in the global DAQ
• HV systems operational
• Commissioning of M2-M5 stations completed Faulty readout channels fixed
RRB October 2009 23
02 March 2009: cables and pipes…
July
200
9:in
stal
latio
n co
mpl
eted
Sept
embe
r 2
009:
first
dat
a!
M1 history in brief
24
Hardware level (L0)
Search for high-pT μ, e, γ and hadron candidates
Software level (High Level Trigger, HLT)
Farm with O(2000) multi-core processors
HLT1: Confirm L0 candidate with more complete
info, add impact parameter and lifetime cuts
HLT2: B reconstruction + selections
Trigger & Online &Computing(CERN,CF,CH,DE,FR,ES,GB,IT,NL)
Hig
h-L
ev
el T
rig
ge
r
2 kHz
Le
vel -
0
L0 e,
40 MHz
1 MHz
L0 had
L0
ECALAlley
Had.Alley
Global reconstruction30 kHz
HLT1
HLT2
MuonAlley
Inclusive selections, +track, topological,
charm, ϕ
& Exclusive selections
Storage: Event size ~35kB
(L0) (HLT1) (HLT2)
Electromagnetic 70 %
> ~80 % > ~90 %Hadronic 50 %
Muon 90 %
Trigger is crucial as σbb is less than 1% of total inelastic cross section and B decays of
interest typically have BR < 10-5
RRB October 2009
RRB October 2009 25
• L0 trigger rechecked following improvements in the MUON, CALO and DAQ The integration of M1 underway.
• L0×HLT1×HLT2 tuned to give an output rate below 2 kHz (for MC data produced at nominal LHCb conditions @ 2×1032).
• HLT farm has been increased to 550 processing units sufficient to receive 1 MHz trigger rate at nominal event size.
• The readout network expanded to nominal capacity. Completion of the farm to reach its full CPU power will be decided in the beginning 2010.
• New MC09 data sample prepared to mimic 2010 conditions. A total of 109
min. bias and 100’s billion signal events run on the GRID. Many improvements in the production system.
• MC09 is being used to tune the trigger settings to the start-up and first physics. Trigger is capable to efficiently select charm in addition to the core B-physics programme.
RRB October 2009 26
Cost and FundingOverall cost remains unchanged at 75 MCHFThe underfunding in 2005 of 2.6 MCHF for the DAQ CPU Farm, hasbeen covered through extra contributions (BMBF Brazil, France,MPI Germany, Spain, UK, US and CERN)
Budget forecast for M&O Cat. A for this year is correct for all the itemsexcept Online and Power estimates
Collaboration Matters• Two new applications for Technical Associates:
- Catholic University of Rio de Janeiro, Brazil - Tier-1 centre CCIN2P3, Lyon, France
Final decision is expected at the next CB in December 2009 Guy Wilkinson (University of Oxford) elected as the next PhysicsCoordinator starting from January 2010
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Physics goals in 2010Early measurements - Calibration signals and minimum bias physics: 108 eventsKey channels available in min bias data with simple trigger: - Ks ππ 95% purities achievable using - Λ pπ kinematical & vertex cuts ~ 40 mins @ 1031
With 2 kHz random trigger
- J/ψ trigger on single muon with pt cut (600k ev./pb-1) one muon unbiased for PID studies and momentum calibration
- J/ψ physics & production cross-sections: ~ 1-5 pb-1
Measure diff. cross-section for promptJ/ψ and bb production cross-section(from secondary J/ψ) in regioninaccessible to other experiments
Λpπ
RRB October 2009
28
Physics goals in 2010
Charm physics: 20 pb-1 and upward ( Exciting possibilities even with low luminosity)
An example: flavour tagged D0KK events for measuring yCP
y = τ(D0 Kπ) / τ(D0 KK) – 1and corresponding CP asymmetry LHCb can collect ~ 105 flavour tagged KK events with 20 pb-1 (same statisticsas BELLE with 540 fb-1 ). Similar data sets for many related channels:
D0ππ, KKππ, KSππ, KSKK, D+ KKπ …
Detailed studies of Dhh (rehearsal for Bhh) - Separate Kπ, KK, ππ and DCS Kπ - Vertex and mass resolutions - LifetimesAccumulate samples of BD(Kπ)π(“ADS” control mode) - Study background environment - Look for any evidence of B+ / B- asymmetries
Analysis commissioning in hadronic modes
RRB October 2009
29
Prospects for most competitive measurements in 2010
With data sample of ~200 pb-1
LHCb should be able to improveTevatron sensitivity for Bs μμ and ϕs
(present ‘central’ value from Tevatron wouldbe confirmed at 5σ level)
Bs μμ
ϕs
RRB October 2009
30
Conclusion
LHCb is ready for data taking
First data will be used for calibration of the detector and trigger in particular. First exploration of low Pt physics at LHC energies. Some high class measurements in the charm sector may be possible with 50 pb-1
With ~ 200 pb-1 data sample LHCb will reach Tevatron sensitivity in a few golden channels in the beauty sector
RRB October 2009
RRB October 2009 31
RRB October 2009 32
Calorimeter hardware status
Non working channels
Non working LED
ECAL 2/6016 none 17 PMT changedLED fixed
HCAL 1/1448 none 4 PMT changed
PS 0/6016 20 Cables plugged Patch Panel
SPD 0/6016 10% channels
Cables cured
RRB October 2009 33
M2 M3 M4 M5
2008
2009
Noi
se r
ate
per
logi
cal c
hann
el
G. Graziani
M2-M5 channel map: 2008 vs 2009A few missing logical channels in 2009 map due to wrong settings (too high threshold)