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Research Masterclass - 2009 Lecture 1 Steve Watts Physics and Astronomy, University of Manchester Research Masterclass - 2009 Lecture 1 Steve Watts Physics and Astronomy, University of Manchester. Advanced Detector Design for Particle Physics (A story of designing an upgrade for ATLAS) First there has to be a physics case. Then, is it technically feasible ? Yes ? But you have to do a lot of detector R&D and work through the problems Succeed ? Yes ? Will someone give the money ? Yes ? Complicated project management to final installation Succeed ? Yes ….get some data Do you find the physics you wanted ???? Note: lecture will be delivered in the form of a research seminar….. ASIDE: COORDINATE SYSTEM AND UNITS Centre of Mass Energy = sqrt(s) = 14 TeV Z-axis Z, θ , φ Use rapidity (y) /pseudo-rapidity ( η ) rather than theta. Why ? dN/dy is Lorentz invariant Units such that c=1……energy, GeV, mass, GeV/c2, momentun GeV/c • A theorist publishes a paper with a new idea – Khoze/Martin/Ryskin Physics Archive – http://arxiv.org/ Higgs or dijet production in double rapidity gap events Authors: V.A. Khoze (U. of Durham), A.D. Martin (U. of Durham), M.G. Ryskin (U. of Durham) (Submitted on 1 Jun 2000) hep-ph/0006005 • Idea is picked up by experimental physicists who look to see if an experiment can be done. Searching for the Higgs Boson at Hadron Colliders using the Missing Mass Method Authors: M.G.Albrow (Fermilab), A.Rostovtsev (ITEP) (Submitted on 28 Sep 2000) hep-ph/0009336 • Not as easy as it looks……years of detector R&D follows….. The FP420 R&D Project: Higgs and New Physics with forward protons at the LHC Authors: M.G. Albrow, and a lot of other people, including Brian Cox, Jeff Forshaw, Cinzia Da Via, Rob Appleby, Andy Pilkington, Steve Watts Fred Loebinger and graduate students from Manchester arXiv:0806.0302 Just published in JINST Nice slide Andrew Brandt The Large Hadron Collider proton-proton collisions at an energy of 14 TeV CMS 26.7 km circumference LHCb ATLAS ALICE Start: September/October 2008 Pictures in this presentation are almost all from the public outreach ATLAS site http://atlas.ch/ LHC - Superconducting 1.8K !! Coldest place on the planet TheTheThe ATLASATLASATLAS DetectorDetectorDetector Diameter 25 m Barrel toroid length 26 m End-cap end-wall chamber span 46 m Overall weight 7000 tons Barcelona October 2009 + Executive Board October 2009 Proposal to STFC sent today. If £££££££ then ready by 2014 !!! MASS ACCEPTANCE – This is a crucial plot……. NOTE 70 GeV/c2 < Mass < 150 420 + 420 120 GeV/c2 < Mass < 500 GeV/c2 420 + 220 300 GeV/c2 < Mass < 1400 GeV/c2 220 + 220 SM = Standard Model Will return to the problem of “overlap background “………………. Luminosity x cross section = events per second Integrated Luminosity ( inverse fb) What level of cross-section can one get ? L = 1034 cm-2sec-1 is nominal LHC luminosity. 80 fb-1 at 14 TeV in year. “30 fb-1” is expected integrated luminosity after first three years WARNING: Total Cross Section is around 100 mb. Trigger rate 100 kHz! There is no reason to think the Higgs is a standard model version…… New results arrive all the time. THE ASSUMPTIONS YOU HAD WHEN YOU STARTED THE JOURNEY MAY NO LONGER BE TRUE. BEWARE !!! AFP ADDS TO THE ATLAS PHYSICS PROGRAMME – COMPLEMENTARY! PLUS LOTS OF STANDARD MODEL “BREAD AND BUTTER” PHYSICS THANKS TO ANDREW BRANDT AND ANDY PILKINGTON FOR UPDATED CASE WHAT ARE THE TECHNICAL AFP = uses LHC beam-line as a spectrometer PROBLEMS ??????? Proton energy loss results in proton trajectory horizontal departure IP1 220m 420m beam y(mm) y(mm) beam V. Avati/ Totem V. Avati/ Totem x(mm) x(mm) Q. How to track the forward protons with standard LHC optics and L = 1034 cm-2s-1 ? A. Hamburg pipe + rad. hard silicon tracking with active edge sensors (3D technology) + fast timing detectors ( 30 ps -> 10 ps) to reject pile up events In principle possible to trigger on protons at Level 1 for 220 detector – important to get at the Higgs to bbar channel.. EXPERIMENTAL PROBLEMS • How to get within a few millimetres of the LHC beam. • Radiation levels are very high close to the beam • Need to track the protons with 1 micro-radian angular precision • 420 m region of the LHC is currently at 1. 8 Kelvin – but it has no magnetic fields !! • To remove pile-up problem you need a radiation hard timing detector with at least 10 pico-second timing resolution. • Need a trigger to select events due to very small cross-section, but, 220 and 420 m are a long way from the central detector ( speed of light) • All components have to work reliably in the LHC tunnel – radiation environment. NONE OF THESE ARE SIMPLE – BUT SOLUTIONS HAVE BEEN FOUND OR R&D IN THE NEXT 1-2 YEARS WILL SOLVE REMAINING PROBLEMS THE STORY CONTINUES NEXT WEEK DIRECTED LEARNING FOR THE NEXT WEEK • Prove that the relationship between the momentum of a charged particle moving in a constant magnetic field and its radius of curvature is; P ( GeV/c) = 0.3 B (Tesla) R (metres) • Derive the missing-mass formula on slide 10. • Estimate the fractional momentum loss for CEP protons at 220 and 420m. Explain why the 220 m region selects a higher mass range than the 420 m region. • Look up and understand rapidity and pseudorapidity • Make estimates for the signal rates for a Standard Model Higgs at various masses for the CEP process at the LHC. Assume a centre of mass energy of 14 TeV. ( Hint: Repeat the exercise in Table 1 of the paper by Albrow et al.) • What is the current state of knowledge of the existence of the Higgs Boson ?? • Look over the FP420 Design Report to prepare for the next lecture on the silicon tracking system..
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