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Status of the CMS Detector

Status of the CMS Detector. The LHC and Dark Matter Ann Arbor, Michigan , January 6 th -9 th , 2009. Paolo Rumerio, University of Maryland On Behalf of the CMS Collaboration. Overview. Installation and Commissioning Beam Days Cosmic Run at Four Tesla Winter Shutdown Activities.

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Status of the CMS Detector

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  1. Status of the CMS Detector The LHC and Dark Matter Ann Arbor, Michigan, January 6th -9th, 2009 Paolo Rumerio, University of Maryland On Behalf of the CMS Collaboration

  2. Overview • Installation and Commissioning • Beam Days • Cosmic Run at Four Tesla • Winter Shutdown Activities LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 2

  3. The CMS Detector YB0 3.8T solenoid HCAL YE-1 Muon chambers Pixel Si Tracker ECAL Iron yoke Some detector component acronyms: Pixel: Barrel (BPix) and Endcap disks (FPix) Tracker: Inner Barrel (TIB), Inner Disks (TID), Outer Barrel (TOB), Endcaps (TEC) Electromagnetic Calorimeter: ECAL Barrel (EB) and ECAL Endcaps (EE) Hadronic Calorimeter: HCAL Barrel (HB), HCAL Endcap (HE), HCAL Forward (HF), HCAL Outer (HO) Muon Chambers: Drift Tubes (DT) in the barrel (also Muon Barrel - MB), Cathode Strip Chambers (CSC) in the endcaps (also Muon Endcaps - ME), Resistive Plate Chambers (RPC) in barrel end endcaps Magnetic field return yoke: Yoke Barrel (YB) and Yoke Endcaps (YE) LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 3

  4. Lowering Barrel Wheels and Endcap Disks Endcap disks: Jan. 07 – Jan. 08 • …………….. • ……….. • ……………. Barrel wheels: Jan. - Oct. 2007 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 4

  5. Installing Detectors Inside the Magnet Inserting HCAL barrel: Mar. 07 Installing ECAL Barrel: ended July 07 • …………….. • ……….. • ……………. Inserting Silicon Strip Tracker: Dec 08. Cabling completed Mar. 08 YB0 After Cabling Dec. 07 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 5

  6. Latest Installed Components ECAL endcaps: completed and fully installed Aug. 08 Beam pipe: insertion and bakeout June 08 • EE and Pixels were installed just before beam and worked quite well very soon Pixels: inserted Aug. 08 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 6

  7. CMS Closed – 3 September 2008 • …………….. • ……….. • ……………. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 7

  8. Commissioning • Magnet Test and Cosmic Challenge (MTCC) took place in summer 2006 on the surface of the experiment location • Commissioning of the magnet and measuring of the field map • Test of a vertical slice of the detector and cosmic data taking • Since May 2007, three- to ten-day-long exercises took place underground with the installed detector components, electronics and services • Increasing size and number of participants, and scope of the exercises • Balancing with • installation schedule • and detector local • commissioning Detector Participation versus Time LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 8

  9. Cosmic Runs Without Magnetic Field • Since March 2008, global runs saw an increasing focus on • stability of operations • cosmic ray data taking (hence named CRUZET - Cosmic RUns at ZEro Tesla) Events Collected Versus Time CRUZET4 : Pixel tracker and EE join (final CMS configuration) CRUZET3: Strip tracker joins Sept.10: Beam CRUZET2 CRUZET1 End March 08 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 9

  10. First Beam • Sun and Mon, Sept. 7 and 8 • Beam 1 (clockwise) single “shots” onto a collimator 150 meters upstream of CMS (also called “splash” events) • Tue, Sept. 9 • 20 additional shots as above • Wed, Sept. 10 • Circulating beams, beam 1 in the morning, beam 2 in the afternoon • Thu, Sept. 11 • RF capture of beam Beam Pickup and CMS Beam Condition Monitors • Fri, Sept. 19th • A faulty electrical connection between a dipole and a quadrupole failed, massive helium loss, and cryogenics and vacuum lost • Beam elements in the region are being extracted and replaced or repaired • During all of these activities, CMS triggered and recorded data • (without CMS magnetic field and with inner tracking systems kept off) LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 10

  11. Event Display of a Beam-on-Collimator Event HCAL Energy ECAL Energy From 2x10^9 protons on a collimator 150 m upstream • …………….. • ……….. • ……………. Drift Tube hits 11 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 11

  12. ECAL vs. HCAL Energy Correlation in Beam-on-Collimator Events • Correlation between reconstructed energy in the CMS Hadron Barrel calorimeter (HB) and Electron Barrel Calorimeter (EB) for beam-on-collimator events in September 2008. • The large reconstructed energy values are the result of the hundreds of thousands of muons which passed through the detector during each event. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 12

  13. Muon Chamber Number of Hitsin Beam-on-Collimator Events • …………….. • ……….. • ……………. • Linearity of the number of hits in the third ring of DT chambers vs. total ECAL energy for beam-on-collimator events LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 13

  14. Synchronization of HCAL from Beam-on-Collimator Events • The pulse arrival time of beam-on-collimator events is predicted using geometry considerations • Left panel: difference between predicted and mean pulse arrival time • beam-on-collimator events of Sep. 10. • HCAL barrel uses tuned integration delays, while HCAL endcap, forward and outer use not tuned delays • Right panel: as above, with the following differences • beam-on-collimator events of Sep. 18 • HCAL uses delays tuned from previous beam-on-collimator runs (except a small region of the Outer calorimeter, omitted here) LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 14

  15. RF Capture of the LHC Beam seen in HCAL Endcap Energy and CMS Trigger Time Distribution of the CMS trigger time versus bunch crossing (BX) number. Before the capture of the LHC beam by the RF system, the trigger timing is spread over a few BXs. After the capture, the trigger timing is sharply peaked at BX=831. Distribution of energy observed in the CMS Endcap Hadron Calorimeter. Before the capture of the LHC beam by the RF system, there is a high rate of energy deposit near the beam line. After the capture, the beam is quite clean. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 15

  16. Evidence of Beam Gas Collisions • Average energy as a function of eta in the CMS Forward Hadron Calorimeter (HF) for circulating beam events at LHC. • The events are triggered by the HF from LHC's Beam 2, which passes through the CMS Detector from negative to positive z. • The events are further selected to contain at least one deposit of 20 GeV in a tower which is registered by both the long and short fiber sections of the tower. • The long and short sections measure the total energy and the hadronic energy of a shower, respectively. • The peak in energy deposition towards positive pseudorapidity is a signature of beam-gas interactions near or within the detector, as the remnants of beam-gas interactions will have a small transverse momentum and a larger longitudinal momentum from the initiating proton. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 16

  17. Beam Halo vs. Cosmic Muons Beam Halo Muon in CSC and HCAL Beam Halo Muons Cosmic Muons  • Distribution of the angles of reconstructed muon tracks with respect to the plane perpendicular to the beam. • Beam halo muons typically make a small angle (blue histogram). • Muons from cosmic rays pass through the cathode strip chambers at a more oblique angle, as seen when the beam is off (black histogram). • When the beam is on (orange-shaded histogram) the distribution consists of two pieces, one of which closely resembles cosmic rays, and the other which matches the beam halo simulation. • The normalization of the blue and black histograms are not based on any calculation; they are meant to guide the eye. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 17

  18. ME1 ME2 ME3 ME4 ME+1 ME+2 ME+3 ME+4 Beam Halo Hit Distribution • Hit distribution in the Cathod Strip Chambers • Red arrows indicate the order beam traversed endcap disks • A few chambers are being fixed during the winter shutdown LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 18

  19. Cosmic Run At Four Tesla - CRAFT LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 19

  20. CRAFT • Four weeks of continuous running • 19 days with magnet at the operational setting of B=3.8 T • Gained operational experience and put in evidence sources of inefficiency • Collected 370 M cosmic events, out of which 290 M with B = 3.8 T. Of those with magnetic field on: • 87% have a muon track reconstructed in the chambers • 3% have a muon track with strip tracker hits (~7.5 M tracks) • 3 x 10-4 have a track with pixel hits (~75K tracks) Number of cosmic events vs. time • Data operation performed satisfactorily • 600 TB of data volume transferred • Prompt reconstruction at Tier 0 completed with a typical latency of 6h • Tier 0 to Tier 1 at average of 240 MB/s LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 20

  21. Tracker Performance • On track Strip clusters S/N ratio, corrected for the track angle • TOB thick sensors: S/N = 32 • TIB/TID thin sensors: S/N = 27/25 • TEC (mixed thickness): S/N = 30 Entries • Track hit finding efficiency • TIB and TOB layers S/N Layer • Muon momentum distribution • high quality tracks (8 hits, one in TIB layers 1-2, one in TOB layers 5-6) • Partial CRAFT statistics (expected >70K tracks at PT>100 GeV for full CRAFT) LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 21

  22. Tracker Alignment • Chi Square distribution • 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) • Only modules with >30 hits considered • TIB 96%, TID 98%, TOB 98%, TEC 94% • HIP algorithm : TIB RMS = 26m TOB RMS = 28m LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 22

  23. Pixel Occupancy and Alignment RMS=47mm RMS=112mm • Barrel aligned at module level (200-300 hits, 89%) • Endcap aligned at half-disk level (8) LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 23

  24. Drift Tube Muon System Data MC MB4 • Residual Distributions • Reasonable agreement between data and MC after cosmic muonarrival time fit • Sigma ~ 200 – 260 m • Sector 4 of wheel -2 is shown here • B field degrades MB1 distribution in wheels +/-2 MB3 MB2 MB1 LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 24

  25. Drift Tubes Drift Velocity Along z-Axis with/without Field • Innermost stations on outer wheels have largest radial field • Maximum difference in drift velocity is 3% LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 25

  26. HCAL Barrel Muon Response • Event selection: • Muon track matching in DT and Tracker • 20 GeV/c < Pµ < 1000 GeV/c • CRAFT: 200 K events • MC: 15 K events CRAFT data HB energy: signal from HB towers corrected for muon path length in HB Test Beam 2006 Pµ = 150 GeV/c Mean signal = 2.8 GeV LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 26

  27. ECAL Barrel Occupancy • Occupancy map of clusters in cosmic muon runs during CRAFT • Avalanche photodiode gain set to x4 the LHC conditions. • Clusters are seeded either from a single crystal or a pair of adjacent crystals above threshold EB+16 EB+7 • Higher occupancy in top and bottom regions (vertical flux of cosmic rays) • Top EB- is closer to the shaft of the CMS P5 pit • Other modulations are due to the cluster efficiency varying with crystal light yield. • EB+7 and EB+16 suffered from low voltage problems - being fixed. • Empty 5x5 crystal regions are trigger towers masked from the readout. LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 27

  28. ECAL Stopping Power Blue dots: CRAFT experimental data Black line:dE/ρdx in PbWO4 Red dashed line: collision loss Blue dashed line: bremsstrahlung radiation • Stopping power for cosmic muons as a function of their momentum • Muon momentum is measured in the tracker • The ECAL energy deposit is measured by the cluster energy matched to the track • The track length in ECAL is estimated from track propagation inside ECAL crystals • Loose selection on the track distance of closest approach to the centre of CMS LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 28

  29. Activities for and after winter shutdown • Detector opening started on Nov 17th • Started a selected list of interventions/repairs for problematic channels (order of the percent) • CMS cooling system maintenance (done) • Installation of Preshower detector in February • Continue the optimization of detector operations • Optimization of online system and procedures to eliminate possible sources of data taking inefficiency • Centralization and optimization of detector control system and monitoring • Consolidation of data quality monitor and certification • Aim to reduce the needed number of shifters and expertise to decrease long term manpower load • Schedule for Resuming Commissioning Activities • Global run sessions to be resumed mid-Feb • First CRUZET (Cosmic RUn at ZEro Tesla) in April • Detector closed around mid-May 2009 • Extended CRAFT (Cosmic Run At Four Tesla) before LHC beam LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 29

  30. Conclusions • A long, intensive and challenging installation and commissioning campaign was carried out successfully • All major components of the detector have been installed and commissioned • Preshower detector will be installed in February • CMS was ready for beam • Collected and exploited at best the beam data delivered before the September 19th incident • A one-month-long cosmic ray run with nominal magnetic field has been taken • Commissioned and verified stability of operations (detector, magnet and operators) • Pointed out inefficiencies and issues to be addressed • Some interventions on detector components are currently being carried out • none of the problems being worked on would have prevented efficient data taking if collisions had been delivered • Schedule for this year has been defined • It will evolve with time, depending on ongoing repair activities and progresses made • Commissioning activities will resume by the end of this month. The goal is to optimize performance, increase efficiency and reduce manpower and expertise needed in control room • CMS will be closed again with enough contingency for being ready for beam, allowing another extended cosmic ray run with magnetic field LHCDM, Ann Arbor, Jan 6th - 9th, 2009 Paolo Rumerio, Maryland Page 30

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