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Accelerator Based Particle Physics Experiments

Accelerator Based Particle Physics Experiments . Su Dong Stanford Student Orientation SLAC session Sep/16/2010. The Fundamental Questions. Are there undiscovered principles of nature: new symmetries, new physical laws ? How can we solve the mystery of dark energy ?

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Accelerator Based Particle Physics Experiments

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  1. Accelerator Based Particle Physics Experiments Su Dong Stanford Student Orientation SLAC session Sep/16/2010

  2. The Fundamental Questions • Are there undiscovered principles of nature: new symmetries, new physical laws ? • How can we solve the mystery of dark energy ? • Are there extra dimensions of space ? • Do all forces become one ? • Why are there so many kinds of particles ? • What is dark matter ? How can we make it in the laboratory ? • What are neutrinos telling us ? • How did the universe come to be ? • What happened to antimatter ?

  3. Accelerator Based Particle Physics Programs

  4. ATLAS @ LHC

  5. 2010 2020 Physics Road map and Detector Evolution Stage 2: 2020 Stage 1: 2015-6 Stage 0: 2012 2015

  6. Physics Opportunities • SLAC physics strategy: • Initial emphasis on physics signature tools (b-tag,jet/missingEt) and trigger. Use Standard Model measurements with early data to validate these tools to prepare for searches of new physics beyond Standard Model. • Current SLAC physics analyses • New physics search and top cross section measurement with b-tag and missing Et • Search for long lived new particles • Lepton jets • Heavy fermions->same sign dileptons • Boosted W • Close collaboration with SLAC theory group • Higgs particle • SuperSymmetry • Large extra-dimensions • The unexpected…

  7. SLAC Involvement in ATLAS 2 Faculty + 1 Panofsky fellow 17+ Staff physicists & professionals 7 Postdocs 6 Grad students & Tier2 computing center staff • Experimental Involvement • Pixel vertex detector and tracking • High Level Trigger and DAQ • Simulation • Tier-2 computing center • ATLAS Detector Upgrades • Opportunities to develop wide variety of experimental skills

  8. Contact Info Dr. Charlie Young young@slac.stanford.edu Prof. Su Dong sudong@slac.stanford.edu Prof. Ariel Schwartzman sch@slac.stanford.edu (resident at CERN) Dr. Andy Haas ahaas@slac.stanford.edu Detailed info on ATLAS@SLAC for students: http://www.slac.stanford.edu/exp/atlas/students/

  9. BaBar @ PEP-II & superB @ Frascati

  10. BaBar Physics CP violation in B0 decays

  11. BaBar Analysis Opportunities • Analysis topics: • ISR->hadronic final states • B/D decay Dalitz analysis • Radiative B decays • fDs • Charmonium like resonances • Data taking ended Apr/08. • 465M BB events • 630M cc events • 460M tt events • Largest sample of Upsilon resonance data • 2-photon, ISR Prof. David Leith leith@slac.stanford.edu Dr. Blair Ratcliff blair@slac.stanford.edu

  12. Focusing DIRC prototype now in Research Yard • Radiator: • 1.7 cm thick, 3.5 cm wide, 3.7 m long fused silica bar (the same used in the BaBar DIRC). • Optical expansion region: • filled with mineral oil to match the fused silica refraction index (KamLand oil). • include optical fiber for the electronics calibration. • Focusing optics: • spherical mirror with 49cm focal length focuses photons onto a detector plane. • Now being tested with new electronics:

  13. snarrow ≈70ps time (ns) snarrow ≈220ps time (ns) snarrow ≈140ps time (ns) Focusing DIRC prototype photon detectorsNucl.Inst.&Meth., A 553 (2005) 96 • 1) Burle 85011-501 MCP-PMT (64 pixels, 6x6mm pad, sTTS ~50-70ps) • Timing resolutions were obtained using a fast laser diode in bench tests with single photons on pad center. • 2) Hamamatsu H-8500 MaPMT (64 pixels, 6x6mm pad, sTTS ~140ps) 3) Hamamatsu H-9500 Flat Panel MaPMT (256 pixels, 3x12mm pad, sTTS ~220ps)

  14. Cherenkov light: tagging color by time Chromatic growth rate: s ~ 40ps/m Cherenkov angle production controlled by nphase: cos c = 1/(nphaseb),nphase(red) < nphase(blue) => c< c Propagation of photons is controlled by ngroup (≠ nphase): vgroup =c0 /ngroup = c0 /[nphase - phase vgroup(red) > vgroup (blue) Analytical calculation: dTOP/Lpath [ns/m] = TOP/Lpath(l) - TOP/Lpath (410nm) Data from the prototype: Geant 4 - without and with pixilization: dTOP/Lpath [ns/m] dTOP/Lpath [ns/m]

  15. Future • We are building a new full size prototype for Super B with new fused silica focusing elements • Will be starting tests in Cosmic Ray Telescope in the SLAC Research Yard this year • Excellent opportunity for hands-on R&D with a innovative new detector.

  16. HPS is a new, small experiment which offers the thesis student exposure to all aspects of experimental particle physics, from experiment design and optimization, to hardware construction, installation and commissioning, and data analysis.Rotation Projects: https://confluence.slac.stanford.edu/display/hpsg/Rotation+Projects+in+Heavy+Photon+Search John Jaros

  17. What is a “Heavy Photon”? • A heavy photon (A’) is a new, ~100 MeV spin one, force-carrying particle that couples to an analogue of electric charge. Because it will mix with “our” photon, it couples to electrons, albeit weakly: • Heavy photons can be produced by electron bremstrahlung off heavy targets and they decay to e+e – • A heavy photon appears as an e+e- resonance on a large background of QED tridents. • Heavy photons can travel detectabledistances before decaying, providing a unique signature. g’ =  e

  18. Why Consider Heavy Photons? • Are there are additional U(1)’s in Nature? If so, they’ll show up by mixing with “our” photon, inducing weak couplings to electric charge. • Heavy Photons could mediate Dark Matter annihilations. Their decays may explain excess high energy electrons and positrons in the cosmic rays; their interactions may account for the DAMA dark matter “detection”. Pamela Positron Excess

  19. SLAC Activities on HPS and APEX SLAC Heavy Photon Group is engaged in two projects: HPS (Heavy Photon Search) has just submitted a proposal to JLab • Review next week at JLab workshop; approval this Fall? • Hope to engineer, construct, test, install by Spring 2012 • Building Si tracker/vertexer, targets, and SVT data acquisition systemGOOD PROJECTS FOR ROTATION STUDENTS APEX (A Prime Experiment) utilizes two large existing spectrometers in Jlab’s Hall A to search for heavy photons • SLAC built targets, helped with test run, and is developing analysis • SLAC will continue helping run and analyze APEX Contact: John Jaros john@slac.stanford.edu Si Tracker APV25 Readout

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