10/12/01T.Bose1 TESTING THE STANDARD MODEL AT THE DØ EXPERIMENT -at present and in the future Tulika Bose for the Columbia-D  group

10/12/01T.Bose2 The Standard Model HEP’s burning questions The Fermilab Tevatron The D  experiment Outline Acknowledgement: Hal Evans – for letting me steal many of his slides!

ForceBosonMass [GeV] Strength GravityG E-M  WeakWW Z0Z Strongg ( M Z ) E-W SymH0H0 >113mf2mf2 ParticleChg [e] Mass [MeV] Leptons ee   0O(<eV) e  Quarks uct+2/31– dsb-1/33– Particles and forces 3

10/12/01T.Bose4 Hugely successful ! But lots of problems/unanswered questions : 19 arbitrary parameters The origin of mass ? Matter/antimatter asymmetry? Gravity ? Standard Model –the good and the bad… Particle Theory HEP Experiments Trash The Feedback Loop Beyond the SM ???

10/12/01T.Bose5 Why is there mass ? Why do some particles have mass while others are massless? Why does, say a top quark, have about 40 times as much mass as a bottom quark? etc. Electric Magnetic EM Weak Electroweak The question of mass

10/12/01T.Bose6 Invents a set of particles with very special properties their interaction with all the standard particles  mass + one new particle – the Higgs boson HEP’s Most Wanted But where is the Higgs???

10/12/01T.Bose7 Higgs in cartoons

10/12/01T.Bose8 What’s the matter with antimatter ? Matter = Right after Big Bang Antimatter But But we exist!!! Where did the anti-matter go?  some asymmetry between matter and antimatter connects the Universe’s matter dominance with elem. pcles Proton decay Rapid expansion

10/12/01T.Bose9 Theoretical framework : CKM matrix atleast 6 quark flavors  complex phase Quarks  CP Violation in B 0, K 0 decays…, Mixing Leptons  Neutrino Oscillations: neutrino mass, mixing & CP Is it zero or non-zero accomodates but does not explain it!!! amount of not enough to account for matter dominance Alternate models include other CP viol. effects experiments sensitive to physics beyond the SM SM

10/12/01T.Bose10 The gravity of the situation Hierarchy problem

Supersymmetry adds a Superpartner for every SM pcle and 5 Higgs: h 0, H 0, A 0, H ± Simplest SUSY models require M h < 135 GeV (!!!) SUSY to the rescue??? Standard ModelSuperpartners ParticleSSparticleS ½0 ½0 ½0 1½ 0½ 1½ 11

10/12/01T.Bose12 new interactions analogous to the ‘color’ force new technicolor fermions like quarks at TeV scale SM particles interact with techi-fermions : the interaction  mass to the SM pcles Answers??? Hierarchy problem solved!

10/12/01T.Bose13 Large extra dimensions ?? Collision energy  disappears Non-conservation of energy sign of new physics String Theory

10/12/01T.Bose14 Take your favourite beyond the SM theory : it looks like the SM at low energies, differences only at high E small corrections to SM predictions  We need to look more precisely and at higher energies The strategy

10/12/01T.Bose15 The truth is out there… Precision measurements: Electroweak Physics: large sample of W & Z bosons W mass (  M(W) ~ 30 MeV/c 2 ) W width, W/Z production properties tri-linear gauge boson couplings Any deviation  new physics ! Top Physics: top only produced at the Tevatron top mass (  M(top) ~ 2.8 GeV/c 2) top pair production cross-section single top production W mass + Top mass constrain Higgs mass

10/12/01T.Bose16 - Large rate: u CP violation and CKM angles u B s mixing u Cross sections u Rare decays The beauty of physics at 2 TeV at Z 0 at  (4S) –All species, including B s, B c,  b, produced

10/12/01T.Bose17 Fermilab Tevatron Circumference: 4 mile 20 feet underground E CM =2 TeV collisions Underlying Event u u d g q q u u d Hard Scatter p (E = 1 TeV) Tevatron

Protons 1.H - Sourceproduce 2.Linac 400 MeV 3.Booster8 GeV 4.Main Injector150 GeV 5.Tevatron980 GeV Antiprotons 1.p-Ni  ’sproduce 2.Accumulator8 GeV 3.Main Injector150 GeV 4.Tevatron980 GeV 5.Recyclerrecovery Tevatron 18

10/12/0119 Linac upgrade, main injector, new antiproton storage ring Ib IIa IIb 03-07… Tot. Anti-p(x10 12 ) Bunches6x636x36140x103 Spacing[ns] E-CM[GeV] Typ. Lumi.[cm -2 s -1 ] (x10 32 ) –5.2 Lumi/weekpb –105 Tot Lumifb –20 Int’s/X’ing –4.8  Extensive upgrade of the D  detector Tevatron upgrade

The layers T.Bose10/12/01 20 General purpose high energy physics detector

10/12/01T.Bose21 >500 people from ~ 50 institutions (17 countries) Run I (’92-’96) ~ 104 publications… EW Physics Top Physics Top quark co-discovered (w/ CDF) March 95 New Phenomena B Physics QCD Run II started March 1, 2001 ! Detector rolled in. All component detectors installed Electronics : final production/installation The international coalition

On the home front 22 FacultyPost-docsGraduate students Hal Evans John Parsons Mike Tuts Leslie Groer Christos Leonidopoulos Georg Steinbrueck Tulika Bose Shaohua Fu Mingcheng Gao Burair Kothari Jovan Mitrevski Responsibilities Hal EvansL2 muon trigger, Si Track Trigger, B phys group co-convener, Run 2b Cal. Trigger Upgrade leader Leslie GroerDetector Commissioning John ParsonsTop/Higgs group Georg SteinbrueckElectroweak group co-convener Mike TutsCalorimeter electronics, Run 2a upgrade co-leader

D  upgrade T.Bose10/12/01 23 Central Scintillator Forward Mini- drift chamb’s Forward Scint Shielding Tracking: Solenoid,Silicon,Fiber Tracker,Preshowers New Electronics,Trigger,DAQ Calorimeter Central PDTs

The real thing! T.Bose10/12/01 24

Tracking Tulika Bose 10/12/01 25 p=qBR Charged Particle B Ionization of atoms by charged particles : electrons knocked out trajectory deduced by measuring ionization at many points along the path curvature of track measured  particle momentum ; amount of ionization per unit length (dE/dx) depends on particle type, p  particle type identified Si wafers: charged pcle passes thru Si  electrons & holes charge collected on strip readout  pcle position  points for track fit n SiO 2 n+n+ p+p+ 300  m VBVB Readout 50  m Si Detector reverse biased diode

Tracking upgrade Silicon Microstrip Tracker (SMT) Central Fiber Tracker (CFT) 2T superconducting solenoid 26

Silicon Microstrip Tracker (SMT) 6 Barrels : 4 layers of Si microstrip detectors axial strips (10  m resolution) Layers 1, 3: double-sided 90 o strips (30  m res.) (single-sided on 2 outer barrels) Layers 2, 4: double-sided 2 o stereo (15  m res.) 12 F-disks & 4 H-disks 793k Channels SVX IIe Readout L2 Trigger (’02) 27 SMT

SMT & CFT SMT high resolution measurements of particle tracks near the beam pipe (10  m res.) measurement of charged particle momenta measurement of secondary vertices for identification of b-jets from top, Higgs, and for b-physics CFT (Scintillating fiber tracker) Fibers (830  m) -Axial & Stereo (±3 o ) on 8 concentric cylinders light from the fibers converted into electrical pulses by Cryogenic (LHe) Photon Detectors (new) VLPC Readout: ~77k Channels (SIFT + SVX IIe) Hit Resolution (~100  m) 28

Calorimeters Calorimeter high density material: particles slow down & stop energy deposited measured  showers  shape of shower distinguishes e,  from hadrons electromagnetic : electrons, positrons, photons hadronic: hadrons which penetrate EM Cal. Detector unchanged from Run I (U-LAr) New electronics to cope with BX frequency 10/12/01 29

Chasing muons Muon detectors tracking muons, measure momentum drift chambers parallel anode wires stretched between two cathode planes elec liberated by ionization moves towards anode energy gain  further ionization  avalanches of elec & +ions drift time (collection time of avalanches)  measure of position scintillation counters excitation of atoms by ionizing particles  luminescence light converted into electrical pulses by Visible light photon counters 30

Pictures Silicon Detector Fiber Tracker Muon Detector 31

Physics Rates ProcessX-Sect or BR Rate (L=2x10 32 ) Beam X’ing7.5 MHz (132ns) Inelastic50 mb 50  b 10 MHz 10 kHz  WX  ZX  bbX 22 nb 1 nb 4.4 Hz 0.2 Hz  e/  + jets  only jets 7.2 pb ~100% 35% 44% 5 / hour 425 fb 22% 56% 7 / day Physics Rates * M(H) = 100 GeV 32

Signal Vs. Background Signals High P T Leptons W/Z, b... High E T Jets Massive Objs Missing E T  ’s, LSP Displaced Vertices b’s... Backgrounds Low E T Jets E T Balanced No High P T Leptons No Displaced Vertices 33

Where is the needle? Out of every trillion proton-antiproton collisions, about ten top-antitop quark pairs are produced!!! 34

D  Trigger System 7 MHz10 kHz1 kHz L1L2 L3 50 Hz Decision time 4.2  s Decision time 100  s Decision time 25ms p p Crossing frequency 7MHz But data acquisition rate is 50 Hz  New 3 Level Trigger System 35 Single Sub-Det’s Towers, Tracks, E T -miss Some correl’s Not deadtimeless Correlations Calibrated Data Physics Objects e, ,j, ,E T -miss Simple Reco Physics Algo’s

L1 & L2 CAL c/f PS CFT SMT MU FPD L1Cal L1PS L1CTT L1Mu L1FPD L2Cal L2PS L2CTT L2STT L2Mu Global L2 Framework Detector Lumi Level 1Level 2 7 Mhz10 khz1 khz Level 3 36

The importance of beauty Some Run II physics programs: Search for the Higgs Boson ( ) Studies of the top quark ( ) B Physics (CP violation etc.) Search for new particles b quarks appear in the final state Tagging of b-quark jets is of utmost importance ! 37

Impact parameter Interesting physics is tagged by b-quarks Impact parameter is a good b-tag Need sensitivity at level of 10's of microns Collision B-Hadron: Flight Length ~ mm’s Decay Vertex B Decay Products Impact Parameter CFT: (100  m res.), SMT (10  m res.) 38

Trigger thresholds soft thresholds allow a fraction of the particles with p T below threshold to fire (BAD!) increase in trigger rate sharp threshold cuts out this background below threshold decrease in trigger rate (VERY GOOD!) precise tracking  more efficient use of the data acquisition bandwidth PTPT Evts Bgrd Signal (magnified) Trig Cut Momentum Resolution Interesting evts  High P T Bgrd dominated by Low P T 39

Physics benefits New Phenomena increase Higgs sensitivity 20%ZH  bb double sensitivityhA  bbbb Top Trigger on Z  bb (increase yield x6) Cut M t systematics in half B-Physics Increase B  K S yield by 50% 40

Silicon Track Trigger Tracks from CFT Data from SMT detectors Form Clusters Define search region in Si Associate clusters to tracks Re-fit track with Si clusters via L2CFT 50  s time budget Global L2 Trigger FRC STC TFC impact parameter trigger Res ~ 30  m at P T =2GeV ; 15  m at P T =15GeV improved momentum resolution: (factor 2-3) sharper thresholds 41

The STT Integration 42

10/12/01T.Bose43 DatesTevatronDØDØ 1/Mar/01Official Run II StartDetector Open 3/Apr/01First Colliding Beam (1x8)Timing In Detectors 27/Apr/0136x36 storesFinal mu-chamber gas 3-17/May/012-week shutdownAll Si cabled – Close det. May-Aug/0136x36 stores w/ shutdownsInstall electronics as avail Jul/01-Sep/01L2 Cal and Muon Oct/01-Nov/011-month shutdownFully instrument Nov/ Run IIa2 fb -1 Jun/2002STT installed 2003Long ShutdownInstall new silicon, etc Run IIb>15 fb -1 Status

10/12/01T.Bose44 Status 36x36 fine tune & stabilize;  stable operation December & January x36 stores Commission CFT & L1 track trigger November Install AFE8 boards & other completionOct 8 - Nov 16 Take data & commission Offline software with real data; Calibration & Alignment Run until ~ Oct 8 Increase L3 rate from 4 Hz to ~100Hz Complete L1 Cal Start bringing up L2 trigger partially By August 15 Continue 36 x 36 running With detector as described before. ~ July 26 ActionDates NOW Done In Preparation In Progress

10/12/01T.Bose45 Muon Data!

10/12/01T.Bose46 Di-muon candidate

Outlook Exciting times ahead! D  is the place to be at! 47 DØ vs. The Standard Model Precision (2 fb -1 )Searches (20 fb -1 )Quark M vs Weak (2 fb -1 ) MWMW 30 MeVH SM 180 sin2  0.03 MtMt 1.6 GeV tan ,M A most 5  xsxs 30 |V tb |12%rare top  10–40K*+-K*+- 700 evts etc…

I.P. resolution with STT Tulika Bose I.P. Resolution ~ 30  m at p T =2GeV ~ 15  m at p T =15GeV 48

Momentum resolution Si precision ~ 10  m, CFT precision ~ 100  m improved momentum resolution: (factor 2-3) Tulika Bose 49

Improved rates 50