First CMS Results with LHC Beam

1. First CMS Results with LHC Beam Toyoko Orimoto California Institute of Technology On behalf of the CMS Collaboration Lake Louise Winter Institute 16-21 February 2009 Toyoko Orimoto, Caltech

2. The CMS Detector Tracker 66M Si pixels & 10M Si strips EM calorimeter: ECAL PbWO4 crystal calorimeter High resolution High granularity, >70k crystals Barrel (EB) & Endcap (EE) Hadronic calorimeter: HCAL Brass & scintillator Barrel (HB), Endcap (HE), Outer (HO) Superconducting Solenoid Very large, 6m x 13m 3.8T, 1.6 GJ stored energy Pixels Tracker ECAL HCAL Solenoid Muons Compact, Modular Weight: 12500 t Diameter: 15m Length: 21.6 m Muon System Barrel: Drift Tubes (DT) Endcap: Cathode Strip Chambers (CSC) Barrel & Endcap interleaved with Resistive Plate Chambers (RPC) Toyoko Orimoto, Caltech

3. Beam Splash Schematic The Large Hadron Collider Collimators Beam 2, E=450 GeV Debris CMS BEAM 146m CMS Beam 1, E=450 GeV 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 Toyoko Orimoto, Caltech

4. Beam Splash Event Display Single beam shots of 2*109 protons onto closed collimators Hundreds of thousands of muons pass through CMS per event ECAL energy HCAL energy Longitudinal views DT muon chamber hits Transverse views LHC Tunnel profile visible Toyoko Orimoto, Caltech

5. Correlation Between Energies in Barrel HCAL and ECAL ~150 TeV in ECAL & ~1000 TeV in HCAL per splash event Beam Splash: ECAL Energy ECAL Endcaps 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). iy iy ix ix ECAL Barrel i Toyoko Orimoto, Caltech TOP BOTTOM i

6. Beam Halo Muons Beam Halo: Muons outside of beam-pipe, arising from decays of pions created when off-axis protons scrape collimators or other beamline elements  Endcap Muon CSC Hit Distribution from Beam Halo Events ME1 ME2 ME3 ME4 LHC Tunnel Profile BEAM 2 Toyoko Orimoto, Caltech

7. Beam Halo Muons 1 muon 3 muons Endcap muon chambers Reconstructed Tracks Barrel muon drift tubes Endcap muon chambers Toyoko Orimoto, Caltech

8. Halo and Cosmic Muon Angles Angle of Muon Tracks wrt Beam Line • Beam halomuons 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. • beam ON data =combination of • beam halo • cosmic rays Toyoko Orimoto, Caltech

9. Beam Halo Before and After RF Capture First RF capture of beam 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 HE Peak Energy Location and Amplitude time h:m Before After HCAL Endcap Energy • Before, high rate of energy deposition near beamline. • After, beam is cleaner, depositing less energy in HE. Y (cm) Y (cm) X (cm) X (cm) Toyoko Orimoto, Caltech

10. Alignment with Beam Halo Muons • Endcap 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) Chamber-by-chamber Diff wrt Photogrammetry • Track-based alignment accuracy: 270 m r 0.35 mrad z • Achieved with 9 min of LHC beam data (~30k events) Before &aftertrack alignment Before &aftertrack alignment Toyoko Orimoto, Caltech

11. 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 Toyoko Orimoto, Caltech

12. CMS Performance with Cosmics 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  Momentum Data vs MC ECAL dE/dx: Experimental data vs Expected stopping power for PbWO4 collision loss brem radiation p (GeV/c) Toyoko Orimoto, Caltech

13. CMS Performance with Cosmics /ndof After Tracker Alignment Si Strip Tracker: Signal to Noise S/N = ~30 Excellent eff > 99% S/N /ndof Pixel & Strip Tracker Alignment: Mean of Residuals Pixel Barrel RMS 47m Strip Inner Barrel RMS 26m Strip Outer Barrel RMS 28m Toyoko Orimoto, Caltech

14. 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! Toyoko Orimoto, Caltech