EPS 2003, July 19, 2003David Buchholz, Northwestern University Performance of the D0 Experiment in Run II Detector Commissioning and Performance Accelerator, Calorimeter, Muon, Tracking, Triggering Separate D0 Computing talk (D. Wicke) Physics Results will be presented in separate parallel talks

EPS 2003, July 19, 2003David Buchholz, Northwestern University Fermilab Accelerator New Main Injector Improved Antiproton source and Booster Increase pbar yield Increase luminosity Increase number of bunches Reduce bunch spacing Reduce # of interactions per crossing Run 1  Run IIa  Run IIb 0.1 fb -1  2 fb -1  ~10 fb-1 Increase beam energy 900  980 GeV Increase x-sections, e.g., of top production by 30-40% - from ~5 to ~7 pb for top pair Run IIa data taking started in spring 2001 Run Ib Run IIa #bunches6X636X36  s (TeV) typ L (cm -2 s -1 )1.6X x10 30  Ldt (pb -1 /week) 3.26 bnch xing (ns)

EPS 2003, July 19, 2003David Buchholz, Northwestern University Integrated Luminosity

EPS 2003, July 19, 2003David Buchholz, Northwestern University Data Taking Efficiency

EPS 2003, July 19, 2003David Buchholz, Northwestern University DØ Run II Detector New for Run II Magnetic tracker 2 Tesla solenoid Silicon microvertex tracker Scintillating fiber tracker Preshower detectors Forward muon detector Forward proton detector Front-end electronics Trigger and DAQ Retained from Run I LrAr calorimeter Central muon detector Muon toroid

EPS 2003, July 19, 2003David Buchholz, Northwestern University Many Preliminary Results Top quark physics (M. Warsinski, L. Shabalina) Re-discovered the top quark, preliminary studies on properties, … Electroweak (N. Varelas) W/Z productions, di-boson production, e+e- forward-backward asymmetry, … New phenomena searches (M. Sanders, T. Nunnemann, D. Baden, M. Wegner) Higgs bosons, supersymmetry, leptoquark, large extra dimensions, Z’, … Heavy flavor (M. Hildreth, P. Balm) resonance reconstructions, masses, lifetimes, branching fractions, rare decays, … QCD (A. Kupco, B. Casey) jet structure, inclusive jet cross section, dijet mass distribution, diffraction…

EPS 2003, July 19, 2003David Buchholz, Northwestern University Tracker

EPS 2003, July 19, 2003David Buchholz, Northwestern University Silicon Microstrip Tracker - SMT 6 Barrels 12 F-disks 4 H-disks BarrelsF-disksH-disks Dble+sngle sided Double sided Single sided Stereo angle0 o, 2 o, 90 o ±15 o ±7.5 o Channels~400K~250K~150K Inner radius2.7 cm2.6 cm9.5 cm Outer radius9.4 cm10.5 cm26 cm Multi-layer barrel cross-section 3m 2 of silicon

EPS 2003, July 19, 2003David Buchholz, Northwestern University Central Fiber Tracker- CFT  ~80K channels with VLPC readout  first sci-fi/VLPC tracker at collider  VLPC's  9K operating temp.  85% QE, excellent S/N  8 layers fiber doublets 0 pe 2 pe 3 pe 4 pe 1 pe LED Calibration

EPS 2003, July 19, 2003David Buchholz, Northwestern University Vertexing Performance Impact parameter resolution getting close to expectation

EPS 2003, July 19, 2003David Buchholz, Northwestern University Average B lifetime

EPS 2003, July 19, 2003David Buchholz, Northwestern University DØ Calorimeter  Uranium-Liquid Argon Calorimeter stable, uniform response, radiation hard Single particle energy resolution – e:  /E = 15% /  E  0.3% –  :  /E = 45% /  E  4% p T = 432 GeV p T = 396 GeV  = 0  = 2  = -2  = 2   =   = 0 New for Run II analog readout electronics 396ns bunch crossing Forward and Central preshower

EPS 2003, July 19, 2003David Buchholz, Northwestern University Preshower Detectors  Scintillation fibers (same as CFT)  Central Region  1 axial layer  2 stereo layer  Forward Region  2 MIP layers  2 shower layers Recover EM energy resolution lost by Solenoid and other material in the central region. Aid in particle ID, used for electron trigger

EPS 2003, July 19, 2003David Buchholz, Northwestern University Contribution to Modern Art Museum D0 Forward Preshower Wedge Part of “Signatures of the Invisible” Museum of Modern Art in New York City

EPS 2003, July 19, 2003David Buchholz, Northwestern University Inclusive Jets Production The errors are dominated by jet energy scale uncertainty Jet energy resolution

EPS 2003, July 19, 2003David Buchholz, Northwestern University Muon Detector  Muon Toroid  Central region,  < 1 (not changed from Run I) u 3 layers drift tubes u 3 layers scintillator counters  Forward region, 1<  < 2 (new) u 3 layers mini drift tubes u 3 layers pixel scintillator counters  New Shielding (very forward direction)  New readout and trigger electronics Muon momentum resolution  p/p ~ p

EPS 2003, July 19, 2003David Buchholz, Northwestern University J/Ψ Dimuon Mass Peak

EPS 2003, July 19, 2003David Buchholz, Northwestern University Z   Mass peak Z      with 104 pb  1 of data

EPS 2003, July 19, 2003David Buchholz, Northwestern University Trigger and DAQ Level 1 Level 2 Level 3 Tape Spec. 5 kHz 1 kHz 50 Hz Operating 1.4 kHz 800 Hz 50 Hz Track and vertex triggers integration underway, Upgrades to L1 and L2 in progress Linux Computers All data available Analog Calorimeter data Prelim. Muon and CFT Muon and CFT tracking Silicon microstrip

EPS 2003, July 19, 2003David Buchholz, Northwestern University Jet Trigger Selection

EPS 2003, July 19, 2003David Buchholz, Northwestern University What’s Next?- Run IIb  Peak Luminosities >4X10 32  Partial upgrade to trigger and front end electronics  Upgrade L1 calorimeter trigger  Upgrade L1 track trigger  Incremental upgrades to L2, L3 triggers and online systems  Integrated Luminosities ~10fb -1  Radiation damage to existing silicon detector after 4fb -1  Replacement silicon tracking system- in progress  Single sided radiation hard detectors  Starts at inner radius of 1.78cm for improved impact resolution

EPS 2003, July 19, 2003David Buchholz, Northwestern University Summary Collider Tevatron is a complex and old machine, it takes time Started slower than we’d like, but making progress Expect to deliver well over 200 pb -1 this year Slow start… Now Strong Program ! Detector DØ detectors are working well Taking physics data with high efficiencies Physics Impressive first results, broader physics potential Presenting results from data samples of 100+ pb -1 this summer Many measurements will supercede those of Run I