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 ? 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 ?

Accelerator Based Particle Physics Programs Expt Description Data Period ATLAS pp collision @7-14 TeV at LHC 2010- BaBar/ superB e+e- @10GeV at SLAC B-factory/ e+e- super B factory at Frascati 1999-2008/ ?? APEX/HPS Heavy Photon Search at Jlab 2010/2012- SiD Silicon Detector for ILC ?? SLD e+e- -> Z0 @91GeV,polarized e- beam 1992-1998

ATLAS @ LHC

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

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…

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

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/

BaBar @ PEP-II & superB @ Frascati

BaBar Physics CP violation in B0 decays

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

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: 8/6/2018

Focusing DIRC prototype photon detectors Nucl. Inst. &Meth Focusing DIRC prototype photon detectors Nucl.Inst.&Meth., A 553 (2005) 96 1) Burle 85011-501 MCP-PMT (64 pixels, 6x6mm pad, sTTS ~50-70ps) snarrow ≈70ps time (ns) 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) snarrow ≈140ps time (ns) 3) Hamamatsu H-9500 Flat Panel MaPMT (256 pixels, 3x12mm pad, sTTS ~220ps) snarrow ≈220ps time (ns) 8/6/2018

Cherenkov light: tagging color by time Chromatic growth rate: s ~ 40ps/m Analytical calculation: dTOP/Lpath [ns/m] = TOP/Lpath(l) - TOP/Lpath (410nm) 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) Geant 4 - without and with pixilization: Data from the prototype: dTOP/Lpath [ns/m] dTOP/Lpath [ns/m] 8/6/2018

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. 8/6/2018

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

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 detectable distances before decaying, providing a unique signature. g’ =  e

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

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 system GOOD 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