Particle Physics Experiments

Transcription

1 Particle Physics Experiments Su Dong Stanford Student Orientation SLAC session Sep/22/2011 1

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? 2

3 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

4 Accelerator based Expt Current Particle Physics Programs Description Data Period APEX/HPS Heavy Photon Search at Jlab 2011/2015- ATLAS pp TeV at LHC BaBar/ superb at SLAC B-factory/ e+e- super B factory at Frascati / 2016?? Non Accel. Expt. Description Data Period CDMS Cryogenic Dark Matter Search EXO Neutrino-less double b decay search with Enriched Xenon Observatory A common primary goal is to search for physics beyond the Standard Model 4

5 LHC

6 Physics Program in Full Swing No new physics yet, but Higgs hunting already getting interesting 6

7 Stage 0: 2013 Stage 1: 2017 Stage 2: 2021 Physics Roadmap and Detector Evolution

8 Physics Preparation Examples Pile up correction with Jet Vertex Fraction (JVF) Jet Energy Scale calibration b-jet trigger menu optimization 8

9 Physics Analysis Examples Boosted Top in jet substructure analysis Stopped long-lived particle search SUSY Search with b+met and simplified models Close collaboration with SLAC/Stanford theory community 9

10 SLAC Involvement in ATLAS 2 Faculty 16+ Staff physicists & professionals 6 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 10

11 Examples of Experimental Activities Pixel clustering Simulation: muon trigger background Modern DAQ concept for upgrade Online beam spot 2mm DOE Site Visit: Aug/2/2011 ATLAS 11

12 Contact Info Prof. Ariel Schwartzman Prof. Su Dong Dr. Charlie Young Detailed info on for students: 12

13 Detector R&D for & Frascati 13

14 BaBar DIRC ---> FDIRC (in 2 easy steps) BaBar DIRC R&D Complete st FDIRC prototype This full scale device is nearly complete now FDIRC design for SuperB DIRC provided the world s best PID at BaBar. It was stable and robust. But new SuperB factories need devices that work at even higher backround levels. Performance: s qc ~ 9.5 mrads Cherenkov Ring Imaging Particle ID Prototype verified the focusing concept, use of highly pixilated detectors, developed MC methods, and demonstrated the previously unobserved principle that the chromatic error can be corrected by timing. Performance: s qc ~ 9.5 mrads => 9.0 mrads after we corrected for the chromatic error - 3D imaging (x, y & time), - 25x smaller volume and - 10x faster than BaBar DIRC. Performance: s qc ~ 9.5 mrads => mrads if we correct for the chromatic error. 14

15 Status of Fused Silica FBLOCK & New Wedge Precise machining on a 5-axis NC machine finished. Presently FBLOCK & New Wedge are being polished to final size and surface quality. Expect delivery in 3-6 weeks. 15

16 CRT: our SLAC test beam Test setup is now ready for the bar box. FBOX support structure arrived at SLAC in July. 16

17 Status of Electronics and Detector plane Have already experience with BLAB2 electronics used in the 1-st FDIRC prototype: Hope to add Up to 16 additional H-8500 tubes 15 H-8500 tubes exist now French TDC/ADC electronics: Will be used to develop and test electronics as well as demonstrate overall FDIRC performance 17

18 Opportunity to Join FDIRC R&D Fabrication, testing, electronics, photon detectors, software development, and analysis. Precise role depends on timing and level of the student s participation. Expected Schedule: Fabrication and assembly complete by early fall Software and analysis system development in parallel System cosmic ray test in the SLAC end station in early winter Data accumulation, analysis, and published results during 2012 Prof. David Leith leith@slac.stanford.edu Dr. Blair Ratcliff blair@slac.stanford.edu Dr. Jaroslav Va Vra jjv@slac.stanford.edu 18

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20 Introduction to Heavy Photons The Heavy Photon (A ) is a conjectured U(1) force particle, a massive vector gauge boson which couples to an analogue of electric charge The A kinetically mixes with the SM, inducing a weak coupling e to electric charge, so heavy photons can be radiated by electrons, and decay to e + e -. Are there more U(1) s in Nature? They proliferate in BSM theories. General considerations imply ~ 10-3 and m A ~100 MeV. A may mediate Dark Matter annihilations and interactions, and thereby account for excess HE e + e - in the cosmic rays and DAMA s direct detection! 20

21 Heavy Photon Search The photon provides a portal to hidden sectors of the universe, since by virtue of kinetic mixing it will weakly mix with hidden sector vector gauge bosons and couple them to electric charge. Dark Matter may be part of such a hidden sector, and may well couple to the hidden sector gauge boson, just as charged particles in our sector couple to the photon. The Heavy Photon Search is a search for a massive vector gauge boson which could mediate Dark Matter interactions with regular matter, be produced in Dark Matter annihilations, and be visible in our sector by decaying to electrons and positrons. 21

22 HPS Setup An intense electron beam impinging on a thin target would produce heavy photons. They are detected in a compact spectrometer/vertex detector by measuring the invariant mass and decay lengths of the e+e- pairs into which they decay. Heavy photons appear as a resonance above the copious QED trident background. For small couplings, the finite A decay length provides a second signature. EM Calorimeter provides a fast trigger and electron ID. Small cross sections and high backgrounds demand large luminosities. HPS survives beam backgrounds by spreading them out maximally in time, capitalizing on 100% CEBAF duty cycle and employing high rate DAQ. A QED 22

23 Present Limits, Region of Interest, HPS Reach / 2 Both naturalness arguments and fits to astrophysical data suggest / 2 ~ m A ~ MeV - GeV Bump Hunt 2.2 GeV Vertex 6.6 GeV 23

24 Schedule and Plans HPS Test Run was approved by JLAB and funded by DOE earlier this year. (Full HPS was conditionally approved, depending on the Test Run.) Design, construction, and preparations for analysis are underway now, to be completed early next year. SLAC is collaborating with JLAB, UCSC, Fermilab, and others on HPS. HPS Test Run will be installed and commissioned at JLAB during Spring 2012 to test detector operations and search for low mass heavy photons. 24

25 Opportunities for Students Rotation Projects are available on HPS this year After the Test Run, lots to do: 2012 Analyze test run data 2012 Remove contingencies for full HPS Refine the design and construct full HPS 2015 Install HPS at JLAB Take data with HPS and analyze Ideal training for all aspects of HEP experimentation Experiment design, planning, and simulation Proposal writing and submission and defense State of the art hardware construction and commissioning Data taking and monitoring Data Analysis Contact: Prof John Jaros 25

26 CDMS

27 Cryogenic Dark Matter Search (CDMS) Stanford and SLAC have leading roles in the CDMS experiment, which seeks to directly detect the Dark Matter that makes up ~25% of the universe 10 kg of new IZip Ge detectors will start taking data in ~2 months at the Soudan Underground Laboratory in Minnesota 100 kg planned for deeper SNOLAB site in Sudbury Canada Sophisticated detector technology to provide robust rejection of backgrounds expect background-free performance up to 1 ton CDMS Collaboration Meeting at SNOLAB 27

28 SuperCDMS Technology Identify Dark Matter by simultaneously measuring phonons and ionization produced in Ge crystals Phonons heat tungsten strips kept at transition between normal and superconducting state - acts as a calorimeter in the traditional sense Ionization signal helps distinguish electron recoils (highly ionizing - largely background) from nuclear recoils from Dark Matter interactions

29 Collage of SLAC / Stanford Efforts in CDMS Photolithographic detector fabrication Automated inspection of detectors Adapt 10 mk dilution refrigerator for SNOLAB Test Facility SNOLAB mechanical and electronic design GEANT4 simulation of backgrounds and phonon/charge propagation in 10 mk Ge

30 CDMS Contacts Prof. Blas Cabrera Dr. Richard Partridge

31 EXO

32 EXO-200 first result 2nbb EXO Is neutrino Dirac or Majorana? 2nbb 0nbb See more details in Prof. Giorgio Gratta s talk on Wednesday Prof. Giorgio Gratta gratta@stanford.edu Prof. Martin Breidenbach mib@slac.stanford.edu Dr. Peter Rowson rowson@slac.stanford.edu

33 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? There is a vibrant particle physics experimental program at SLAC/Stanford seeking answers with variety of approaches 33