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

Collimators

146m

CMSCMSDebris

Beam Splash Schematic

Beam 2, E=450 GeV

Beam 1, E=450 GeV

CMS

The Large Hadron ColliderThe Large Hadron Collider

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 4

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

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 5

Beam Splash: ECAL Energy

TOP BOTTOM

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.

Endcap calibrations were not yet applied (lowest gain photo-detectors are nearest the beam pipe).

ECAL Endcaps

ECAL BarrelECAL Barrelixix

iy iy

i

i

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

ME4ME3ME2ME1LHC Tunnel Profile

Endcap Muon CSC Hit Distribution from Beam Halo EventsEndcap Muon CSC Hit Distribution from Beam Halo Events

BEAM 2

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 7

Beam Halo Muons

Endcap muon chambers

3 muons

1 muon

Barrel muon drift tubes

Endcap muon chambers

Reconstructed Tracks

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 8

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 = combination of • beam halo • cosmic rays

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 9

Beam Halo Before and After RF Capture

Beam Halo Rates in Muon Endcaps

• CSC halo trigger rate in the minus endcap as a function of 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 HE.

BeforeBefore AfterAfter

First RF capture of beam

time h:m

X (cm)X (cm)

Y (

cm)

Y (

cm)

HE Peak Energy Location and Amplitude

First CMS Results with LHC Beam Toyoko Orimoto, Caltech 10

Alignment with Beam Halo MuonsEndcap Muon Cathode Strip Chamber Alignment Use tracks passing through overlap of 2 chambers Determine relative pos by requiring consistency

between 2 track segments r position,z rotation in layer's plane

Cross-check against photogrammetry (PG)

Track-based alignment accuracy: 270 m r0.35 mrad z

Achieved with 9 min of LHC beam data (~30k events)

Chamber-by-chamber Diff wrt Photogrammetry

Before & after track alignment

Before & after track alignment

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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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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

Strip Outer BarrelRMS28m

S/N = ~30

Excellent eff > 99%

Si Strip Tracker: Signal to Noise

S/N

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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!