First CMS Results with LHC Beam Toyoko Orimoto, Caltech 1
First CMS Results First CMS Results with LHC Beamwith LHC Beam
Toyoko OrimotoToyoko OrimotoCalifornia Institute of TechnologyCalifornia Institute of Technology
On behalf of the CMS CollaborationOn behalf of the CMS Collaboration
Lake Louise Winter InstituteLake Louise Winter Institute16-21 February 200916-21 February 2009
First CMS Results with LHC Beam Toyoko Orimoto, Caltech 2
The CMS Detector
PixelsTrackerECALHCALSolenoidMuons
Compact, ModularWeight: 12500 tDiameter: 15mLength: 21.6 m
EM calorimeter: ECALPbWO4 crystal calorimeterHigh resolutionHigh granularity, >70k crystalsBarrel (EB) & Endcap (EE)Hadronic calorimeter: HCALBrass & scintillatorBarrel (HB), Endcap (HE), Outer (HO)
Tracker66M Si pixels & 10M Si strips
Superconducting SolenoidVery large, 6m x 13m3.8T, 1.6 GJ stored energyMuon SystemBarrel: Drift Tubes (DT) Endcap: Cathode Strip Chambers (CSC)Barrel & Endcap interleaved with Resistive Plate Chambers (RPC)
First CMS Results with LHC Beam Toyoko Orimoto, Caltech 3
Timeline: First LHC Beams
• 7-9 September
• Single shots of beam 1 onto closed collimator 150m upstream of CMS (“beam splash” events)
• 10 September (Media Day!)
• Beam 1 circulated in the morning, 3 turns within 1 hour!
• Beam 2 circulated by 3:00pm, 300 turns by evening
• 11 September
• RF system captures beam at evening (millions of orbits)
• During all these activities, CMS triggered and recorded data
• ~40 hours of beam to CMS
Beam 2, E=450 GeV
Beam 1, E=450 GeV
CMS
The Large Hadron ColliderThe Large Hadron Collider
BEAM
Collimators
146m
CMSCMSDebris
Beam Splash Schematic
BEAM
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Beam Splash Event Display
HCAL energyHCAL energy ECAL energyECAL energy
DT muon DT muon chamber chamber
hitshits
LHC Tunnel profile visible
LHC Tunnel profile visible
Longitudinal views
Transverse views
Single beam shots of 2*109 protons onto closed collimatorsHundreds of thousands of muons pass through CMS per event
BEAMDebris
First CMS Results with LHC Beam Toyoko Orimoto, Caltech 5
Beam Splash: ECAL Energy
Enormous amount of energy deposited in calorimeters!
~200 TeV energy deposited in EB+EE
> 99% of ECAL channels fired
Beam (clockwise) came from plus side.
ECAL Endcaps
crystal index ix
cry
sta
l in
dex
iy
crystal index ix
cry
sta
l in
dex
iy
En
erg
y (G
eV
)
TOP BOTTOM
ECAL BarrelECAL Barrel
cry
sta
l in
dex
i
crystal index i
En
erg
y (G
eV
)
Correlation Between Energies Correlation Between Energies
in Barrel HCAL and ECALin Barrel HCAL and ECAL
~150 TeV in ECAL & ~1000 TeV in HCAL
per splash event
First CMS Results with LHC Beam Toyoko Orimoto, Caltech 6
Beam Halo Muons
Beam Halo:Beam Halo: Muons outside of beam-pipe, arising from decays of pions created when off-axis protons scrape collimators or other beamline elements
Muon Endcap Layer -1
LHC Tunnel Profile
Endcap Muon Cathode Strip Chamber Hits from Beam Halo EventsEndcap Muon Cathode Strip Chamber Hits from Beam Halo EventsMuon Endcap Layer -2 Muon Endcap Layer -3 Muon Endcap Layer -4
BEAM
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Beam Halo Muons
Endcap muon chambers
3 muons
1 muon
Barrel muon drift tubes
Endcap muon chambers
Reconstructed Tracks
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Halo and Cosmic Muon Angles
• Beam halo muons to make a small angle
• Cosmic Ray muons pass through the CSCs at a more oblique angle
• Beam-on distribution consists of two pieces, one resembling cosmic rays and the other matching the beam halo simulation.
Angle of Muon Tracks wrt Beam LineAngle of Muon Tracks wrt Beam Line
beam ON data =beam halo MC
+ cosmic ray data
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Beam Halo Before and After RF Capture
Beam Halo Rates in Muon Endcaps
• Muon Endcap (CSC) halo trigger rate in the minus endcap vs time.
• First successful capture lasted for 10 min and ended with beam abort
HCAL Endcap Energy
• Before, high rate of energy deposition near beamline.
• After, beam is cleaner, depositing less energy in HCAL endcap.
BeforeBefore AfterAfter
First RF capture of beam
time h:m
X (cm)X (cm)
Y (
cm)
Y (
cm)
HCAL Endcap Peak Energy Location & Amp
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CMS Performance with Cosmics
collision loss
brem radiation
ECAL dE/dx:Experimental data vs Expected stopping power for PbWO4
MomentumData vs MC
p (GeV/c)
CRAFT: Cosmic Run at Full Tesla
• ~300 M cosmic events collected
• Field at 3.8T operated for ~1 month
• Participation from all subsystems
• Detector performance studies as well as detailed cosmics studies ongoing
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CMS Performance with Cosmics/ndof After Tracker Alignment
/ndof
Strip Inner BarrelRMS26m
Pixel Barrel
RMS 47m
Pixel & Strip Tracker Alignment: Mean of Residuals
S/N = ~30
Excellent eff > 99%
Si Strip Tracker: Signal to Noise
S/N
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CMS Detector Status• Since beginning of September 2008
• All installed CMS sub-detectors in global readout routinely
• All triggers operational
• Stability of running with all CMS components proven
• LHC clock and orbit signals tested
• Synchronization to few ns or better
• Have continued global data-taking with cosmics
• CRAFT: Cosmic Run at Full Tesla
• Detector opening started Nov 17th
• Interventions/repairs for problematic channels
• Installation of Preshower detector
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Conclusions
• After many years of design & construction, CMS is commissioned and has collected first data with LHC
• Detector performance proven with beam splash, beam halo, as well as cosmics with and without B field.
Expect more results, not just with single beam or cosmics, but with collisions!