LHC – New era ? Large Hadron Collider (protons + protons) C.H. Wang/nuu

Outline What is LHC? CERN Accelerator Recent News of LHC History of Particle Physics What Comes from LHC Summary

Budget/Size/Man Power/Fact The largest machine in the world... Circumference : m Cost: 3 billion Euro (machine only)/6.0 billion (~15% detector) The fastest racetrack on the planet... v = c  7 TeV per proton The emptiest space in the Solar System... The internal pressure of the LHC is atm, ten times less than the pressure on the Moon!

The hottest spots in the galaxy, but even colder than outer space... When two beams of protons collide, they will generate temperatures more than times hotter than the heart of the Sun. The 'cryogenic distribution system', which circulates superfluid helium around the accelerator ring, keeps the LHC at a super cool temperature of °C (1.9 K) – even colder than outer space!

The biggest and most sophisticated detectors ever built... Detector (scientists): CMS (2000), ATLAS(2000), ALICE(1000), LHCb(700) 600 million collisions per second The most powerful supercomputer system in the world... The data recorded by each of the big experiments at the LHC will fill around dual layer DVDs every year.  GRID

First Week of LHC LHC started the beams on 10 September. On 18 September 2008, LHC successfully got beams around the ring in both directions on the first day with several hundred orbits being achieved. The next step in the commissioning process is to bring in the radio-frequency (RF) system that keeps the beams bunched, rather than spreading out around the ring, and will eventually accelerate them to 7 TeV. Next: To collide the beams !

Last Week of LHC Geneva, 23 September Investigations at CERN1 following a large helium leak into sector 3-4 of the Large Hadron Collider (LHC) tunnel have indicated that the most likely cause of the incident was a faulty electrical connection between two of the accelerator’s magnets. Before a full understanding of the incident can be established, however, the sector has to be brought to room temperature and the magnets involved opened up for inspection. This will take three to four weeks. Restart the accelerator complex to early spring LHC beams will then follow.

History of Particle Physics What are the Elementary Constituents of Matter? What are the forces that control their behaviour at the most basic level?

electron/proton/neutron/neutrino/photon….. anti-matter Proposed in 1928 and discovered in 1932: positrons (balloon flight) – Carl Anderson, PR43, 491 (1933)

Neutron discovered by James Chadwick /1932 Fermi theory of beta decay n -> p + + e - + ν e /1933 (Weak Interaction) Yukawa’s meson hypothesis on nuclear force /1935  (muon) lepton discovered by Carl Anderson /1937 (Yukawa?) Charged  meson discovered  + ->  + +  /1946 Neutral  meson discovered  o ->  /1950

By 1950 QED (Quantum Electrodynamics) -- quantum theory of electrodynamics. Charged particles interact via exchange of photons. Richard Feymann/ Julian Schwinger/ Tomonaga

In 1947 kaons were discovered in the cosmic rays. At first, people thought kaons should have decayed to pions relatively rapidly. But this was not the case. And scientists did think this strange. And so the kaon was assigned a property called "strange." Discovery of anti-proton in In 1956, neutrino was detected directly.  e  p  e + + n

    p           W h a t a j u n g l e !

From Fermi Lab: donut.fnal.gov/web_pages/standardmodelpg/TheStandardModel.htmlhttp://www- donut.fnal.gov/web_pages/standardmodelpg/TheStandardModel.html Tsung-Dao Lee and Chen Ning Yang propose parity non-conservation in certain sub-atomic processes, which is confirmed by experimentalist Chien- Shiung Wu

-1962 The first experimental observation of the muon neutrino Quarks are proposed by Murray Gell-Mann and George Zweig   was discovered Steven Weinberg, Sheldon Glashow (collaboration) and Abdus Salam (independent) create the electro-weak theory, unifying the electromagnetic and weak nuclear force (they win Nobel prizes in 1979) Standard model of particle physics is developed (QCD) The charmed quark is observed Evidence of the tau lepton is found Experimenters find proof of the bottom quark

 / K L detection 14/15 lyr. RPC+Fe C entral D rift C hamber small cell +He/C 2 H 6 CsI(Tl) 16X 0 Aerogel Cherenkov cnt. n=1.015~1.030 Si vtx. det. 3/4 lyr. DSSD TOF conter SC solenoid 1.5T 8 GeV e  3.5 GeV e  Belle Detector

-1983 Carlo Rubbia discovers the W and Z bosons, mediators of the weak-force Planning for LHC (Large Hadron Collider) at CERN begins Evidence for the top quark, the final undiscovered quark, is found at Fermilab The tau neutrino, the last piece to the standard model, (with the exceptopm of the higgs particle) is observed at Fermilab

Size: 46 m long, 25 m high and 25 m wide. The ATLAS detector is the largest volume particle detector ever constructed. Weight: 7000 tonnes Size: 21 m long, 15 m wide and 15 m high. Weight: tonnes

The Standard Model of Particle Physics (Electroweak + Strong) Fundamental Particles: quarks & leptons In weak decays, quarks will change flavors. (quark mixing) Source of the mass: Higgs Boson

Proton-Proton Collision (LHC) What is our plan? Search for Higgs! H -> Z 0 Z 0 / Z0 -> l + l - What is our dream? New Particles! Clues for new physics!

Summary LHC successfully ejects and maintain the beams inside the beam pipe. Maintenance is a challenge issue. Plan to collide beams middle next year. Hope for the unexpected results!