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 First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Toyoko Orimoto, Caltech The CMS Detector 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) Tracker 66M Si pixels & 10M Si strips Superconducting Solenoid Very large, 6m x 13m 3.8T, 1.6 GJ stored energy Muon System Barrel: Drift Tubes (DT) Endcap: Cathode Strip Chambers (CSC) Barrel & Endcap interleaved with Resistive Plate Chambers (RPC) Pixels Tracker ECAL HCAL Solenoid Muons Compact, Modular Weight: 12500 t Diameter: 15m Length: 21.6 m First CMS Results with LHC Beam Toyoko Orimoto, Caltech

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) BEAM Collimators 146m CMS Debris Beam Splash Schematic Beam 2, E=450 GeV Beam 1, E=450 GeV CMS The Large Hadron Collider 19 September Faulty electrical connection between dipole and quadrupole failed, resulting in massive helium loss, cryogenics and vacuum lost Beam elements being removed and replaced/repaired During all these activities, CMS triggered and recorded data ~40 hours of beam to CMS First CMS Results with LHC Beam Toyoko Orimoto, Caltech

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

Beam Splash: ECAL Energy Correlation Between Energies in Barrel HCAL and ECAL ~150 TeV in ECAL & ~1000 TeV in HCAL per splash event ECAL Endcaps Energy (GeV) 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. crystal index iy crystal index iy crystal index ix crystal index ix TOP BOTTOM ECAL Barrel crystal index i crystal index i Energy (GeV) First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Toyoko Orimoto, Caltech 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 Cathode Strip Chamber Hits from Beam Halo Events Muon Endcap Layer -1 Muon Endcap Layer -2 Muon Endcap Layer -3 Muon Endcap Layer -4 LHC Tunnel Profile A useful tool for alignment and time synchronization BEAM First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Toyoko Orimoto, Caltech Beam Halo Muons 1 muon 3 muons Reconstructed Tracks Endcap muon chambers Three muons are reconstructed in the Cathode Strip Chambers (CSC's). The chambers with hits are shown as trapezoidal volumes in white, with yellow strips running in the radial direction, and purple wires running in the azimuthal direction. The long blue lines threading several chambers represent muon trajectories reconstructed offline. One line appears to be bent due to multiple scattering of the muon in the calorimeter. This particular beam halo / beam gas event is unusual in having three reconstructed muons; most events have one. Barrel muon drift tubes Endcap muon chambers First CMS Results with LHC Beam Toyoko Orimoto, Caltech 7

Halo and Cosmic Muon Angles Angle of Muon Tracks wrt Beam Line beam ON data = beam halo MC + cosmic ray data The normalization of the blue and black histograms are not based on any calculation; they are meant to guide the eye. 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. First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Beam Halo Before and After RF Capture First RF capture of beam 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 Peak Energy Location & Amp time h:m Before After HCAL Endcap Energy Before, high rate of energy deposition near beamline. After, beam is cleaner, depositing less energy in HCAL endcap. This plot shows the CSC halo trigger rate in the MINUS endcap as a function of time. The yellowish band indicates the first successful RF capture of the LHC beam (beam 2) which lasted about 10min (and ended with the first automatic beam abort). One sees rate jumps preceding this due to earlier capture attempts. These rates are defined by averaging over a 10 s interval. Sectors 1 and 6 are mostly horizontal on the inside part of the ring Y (cm) Y (cm) X (cm) X (cm) First CMS Results with LHC Beam Toyoko Orimoto, Caltech 9

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) First CMS Results with LHC Beam Toyoko Orimoto, Caltech

CMS Performance with Cosmics Si Strip Tracker: Signal to Noise /ndof After Tracker Alignment 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 S/N ~30 Excellent eff > 99% Using 4M tracks for alignment and 1M for validation “Unaligned” is the nominal geometry “CRUZET” is the geometry obtained from the B=0T runs using the Hits and Impact Point method and survey constraints “CRAFTHIP” is the geometry obtained from the Hits and Impact Point algorithm applied to CRAFT data, including survey constraints “CRAFTMP” is the geometry obtained from the Millepede algorithm applied to CRAFT data Mean of residual distributions (cm) Sensitive to module displacements Only modules with >30 hits considered TIB 96%, TID 98%, TOB 98%, TEC 94% HIP algo: TIB RMS = 26m TOB RMS = 28m First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Toyoko Orimoto, Caltech 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 First CMS Results with LHC Beam Toyoko Orimoto, Caltech

Toyoko Orimoto, Caltech 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! First CMS Results with LHC Beam Toyoko Orimoto, Caltech