The Large Hadron Collider Is Turning On (Again) In November

1. The Large Hadron Collider Is Turning On (Again) In November Michael Shupe Department of Physics University of Arizona

2. Large Hadron Collider French/Swiss Countryside outside Geneva, Switzerland.

3. Large Hadron Collider At four points around the ring the two beams are brought together for head-on collisions. The beams are actually composed of many bunches of protons, with bunch crossings (collisions) every 25 nanoseconds. At nominal energy, it takes 90 microseconds for a proton to make one revolution. • 7 GeV 3

4. LHC experiments, and a few of the physicists…

5. The ATLAS Detector 7000 tons of detector sits 100m underground 150 million sensors incorporated into ATLAS

6. The ATLAS Detector One of four experiments at the LHC: 46m in length and 25m in diameter. 100 m underground.

10. ATLAS By The Numbers • Size • ½ size of Notre Dame Cathedral • Weighs as much as 100 747 airplanes • Data • 3200 terabytes expected • Equivalent to 7km of CDs stacked vertically • Energy and Temperature • 7 times the energy of any existing accelerator • 100,000 times hotter than the sun • Collaboration • 2500 physicists • 37 countries • 169 universities and laboratories

11. What’s the LHC for? To study the fundamental building blocks of nature, and the interactions among them. Electromagnetic Force Strong (Nuclear) Force Weak Force (Changes particle types) Gravity (Gravitons?)

12. LHC and the Big Bang At the LHC we will recreate temperatures similar to those found about one nanosecond after the Big Bang.

13. What Can Be Found at the LHC? • Source of mass: find the Higgs particle? • Confirm new theories: Supersymmetry? • Astrophysical phenomena: Dark Matter particles? • More BTSM: Compositeness?, Extra Large Dimensions? • Complete surprises? (See the history of this field.) Dennis Overbye

14. Mass puzzle, and the Higgs Particle. Providing mass to all massive particles is role of the predicted Higgs particle. We are searching for the Higgs at the LHC. The standard model of particle physics works wonderfully well. • Unification of the Electromagnetic and Weak Forces. • Form of the Strong Force. • But it does not explain why particles have masses nor why some particles are very light while others are very massive.

15. Finding a Higgs • A Higgs, if it is produced at the LHC, will decay immediately into other lighter particles. • Such particles can be reconstructed in a detector (ATLAS, CMS). • By searching for these “daughter” particles, one can reconstruct the Higgs. • Many other decays can mimic a Higgs, producing background. A few hundred Higgs events seen after a few years of running

16. Dark Matter • From Newtonian mechanics we expect the rotational velocity of galaxies to drop off with radius. • Pluto’s orbit is about 250 times longer than Earth’s even though it’s only 40 times farther from the Sun. • Data show that velocities remain nearly constant. • Galaxies should fly apart. • Indication that all mass in galaxies is not contained in stars.

17. Dark Matter Candidates • Weakly Interacting Massive Particles • WIMPs • As yet undiscovered particle/particles • Only interacts via the weak force and gravity. • A leading WIMP candidate is the neutralino. • If this particle exists, it is likely to be found at the LHC.

18. This is one of the new-physics directions being pursued at Arizona: • Leading an effort to search for a charged Higgs particle decaying into a chargino and neutralino. • Definitive evidence for physics beyond the Standard Model. • The neutralino may be the solution to the dark matter problem. • One of many scenarios for the decay of the Higgs particle.

19. The University of Arizona Team Faculty Research Associates & Staff Students

20. The ATLAS Detector • Arizona’s contributions to ATLAS. • Forward Calorimeter • Forward Muon Chambers • Radiation Studies • Development of Data Analysis

21. LAr Calorimeters Arizona

22. Forward Calorimeter Close-up photo of the front of one of the forward calorimeter modules during construction. One of the prototypes for this detector element is located in the hallway. Cutaway drawing of one FCal module. The LHC accelerator vacuum beam pipe passes through the hole in the middle of the module.

23. Forward Calorimeter Construction in the Basement of Physics: Even Experimentalists Dress Up Occasionally

24. Forward Calorimeter Installation

25. Muon Detector Muons are the only charged particles which can pass through the calorimeters. The muon system detects such particles and can determine their charge and momentum.

26. CSC (Cathode Strip Chambers) CSCs

27. CSC Chambers

28. One of My Physics Interests: Quark Compositeness • Are there smaller things inside quarks? • Recall Rutherford Scattering: excess events at large angles. • LHC analogy is quark collisions with large momentum transfer. Small scattering centers inside quarks would modify the pT distribution. (“Jets” simulation for ATLAS shown at right.)

29. One of My Service Contributions: ATLAS Backgrounds Simulation, and Shielding Design

30. Installation of bridge piece for ATLAS forward shield.

31. What next? • Next beam in LHC: November • First collisions: December. • First low energy data: Spring 2010 • Increase in rate & energy: 2010 – 2011 • First Discoveries in 2011…

32. Summary • The LHC turn on has just begun. • World’s largest scientific experiment to date. • Expect to find answers to many fundamental questions. • Mass, Dark Matter, Supersymmetry, and More! • The University of Arizona has played a significant role in developing and building this device. • Exciting times ahead…

33. CSC Muon Chambers Resolution is 70 μm

34. CSC Calibration System • Improves resolution • Allows detector to operated in a high rate environment.

35. EM Calorimeter Endcap Barrel in cryostat