Transcript LHC – New era - National Chiao Tung University

LHC – New era ?
Large Hadron Collider (protons + protons)
C.H. Wang/nuu
Outline
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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 : 26659 m
• Cost: 3 billion Euro (machine only)/6.0 billion (~15%
detector)
• The fastest racetrack on the planet...
• v = 99.9999991c  7 TeV per proton
• The emptiest space in the Solar System...
• The internal pressure of the LHC is 10-13 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 100 000 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 -271.3°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 100 000 dual layer DVDs every year.
 GRID
First Week of LHC
http://public.web.cern.ch/public/
• 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 2008. 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 2009.
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?
1930 - 1950
• 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- + νe /1933
(Weak Interaction)
• Yukawa’s meson hypothesis on nuclear force /1935
•
m(muon) lepton discovered by Carl Anderson /1937
(Yukawa?)
• Charged p meson discovered p+ -> m+ +nm /1946
• Neutral p meson discovered po -> g +g /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 1955.
• In 1956, neutrino was detected directly.
ne + p  e+ + n
S
0
K
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D
D
p
-
-
p
D
o
W
+
p
+
K
L
o
+
D
++
-
p
0
K
+
What a jungle!
From Fermi Lab:
http://wwwdonut.fnal.gov/web_pages/standardmodelpg/TheStandardModel.html
• -1956-57 Tsung-Dao Lee and Chen Ning Yang propose parity non-conservation in
certain sub-atomic processes, which is confirmed by experimentalist ChienShiung Wu
• -1962 The first experimental observation of the muon
neutrino
• -1964 Quarks are proposed by Murray Gell-Mann and
George Zweig
• -1964 W- was discovered.
• -1967 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)
• -1970-73 Standard model of particle physics is
developed (QCD)
• -1974 The charmed quark is observed
• -1975 Evidence of the tau lepton is found
• -1977 Experimenters find proof of the bottom quark
Belle Detector
SC solenoid
1.5T
Aerogel Cherenkov cnt.
n=1.015~1.030
3.5 GeV e+
CsI(Tl)
16X0
TOF conter
8 GeV e-
Central Drift Chamber
small cell +He/C2H6
Si vtx. det.
3/4 lyr. DSSD
m / KL detection
14/15 lyr. RPC+Fe
m
Bs
Bs
+
nm
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Ds
p

-
K
K
+
• -1983 Carlo Rubbia discovers the W and Z
bosons, mediators of the weak-force
• -1994 Planning for LHC (Large Hadron Collider)
at CERN begins
• -1995 Evidence for the top quark, the final
undiscovered quark, is found at Fermilab
• -2000 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: 12 500 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 -> Z0 Z0 / 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!