An Overview of High Energy Physics

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An Overview of High Energy Physics

• Wan Ahmad Tajuddin Wan Abdullah
• Jabatan Fizik, Universiti Malaya
• 50603 Kuala Lumpur
• http//fizik.um.edu.my/cgi-bin/hitkat?wat
• July 2004

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contents

• dulu
• kini
• seterusnya

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• 624-547 B.C. Thales of Miletus postulates that
  water is the basic substance of the Earth. He
  also was acquainted with the attractive power of
  magnets and rubbed amber.
• 580-500 B.C. Pythagoras held that the Earth was
  spherical. He sought a mathematical understanding
  of the universe.
• 500-428 B.C., 484-424 B.C. Anaxagoras and
  Empedocles. Anaxagoras challenged the previous
  Greek contention about the creation and
  destruction of matter by teaching that changes in
  matter are due to different orderings of
  indivisible particles (thus his teachings were a
  precursor to the law of the conservation of
  matter). Empedocles reduced these indivisible
  partices into four elements earth, air, fire,
  and water.
• 460 - 370 B.C. Democritus developed the theory
  that the universe consists of empty space and an
  (almost) infinite number of invisible particles
  which differ from each other in form, position,
  and arrangement. All matter is made of
  indivisible particles called atoms.
• 384-322 B.C. Aristotle formalized the gathering
  of scientific knowledge. While it is difficult to
  point to one particular theory, the total result
  of his compilation of knowledge was to provide
  the fundamental basis of science for a thousand
  years.
• 310-230 B.C. Aristarchus describes a cosmology
  identical to that proposed by Copernicus 2,000
  years later. However, given the great prestige of
  Aristotle, Aristarchus' heliocentric model was
  rejected in favor of the geocentric model.
• 287-212 B.C. Archimedes was a great pioneer in
  theoretical physics. He provided the foundations
  of hydrostatics.
• 70-147 AD Ptolemy of Alexandria collected the
  optical knowledge of the time. He also invented a
  complex theory of planetary motion.
• 1000 AD Alhazen, an Arab, produced 7 books on
  optics.
• 1214 - 1294 AD Roger Bacon taught that in order
  to learn the secrets of nature we must first
  observe. He thus provided the method by which
  people can develop deductive theories using
  evidence from the natural world. experimental
  method
• 1473 - 1543 AD Nicholaus Copernicus set forth the
  theory that the earth revolves around the sun.
  This heliocentric model was revolutionary in that
  it challenged the previous dogma of scientific
  authority of Aristotle, and caused a complete
  scientific and philosophical upheaval. man not
  at centre of universe

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• 1564 - 1642 Galileo Galilei is considered by many
  to be the father of modern physics because of his
  willingness to replace old assumptions in favor
  of new scientifically deduced theories. He is
  famous for his celestial theories, and his works
  on mechanics paved the way for Newton.
• 1546 - 1601, 1571 - 1630 Tycho Brahe and Johannes
  Kepler. Brahe's accurate celestial data allow
  Kepler to develop his theory of elliptical
  planetary motion and provide evidence for the
  Copernican system. In addition, Kepler writes a
  qualitative description of gravitation.
• 1642 - 1727 Sir Isaac Newton develops the laws of
  mechanics (now called classical mechanics) which
  explains object motion in a mathematical fashion.
  
• 1773 - 1829 Thomas Young develops the wave theory
  of light and describes light interference.
• 1791 - 1867 Michael Faraday creates the electric
  motor, and develops an understanding of
  electromagnetic induction, which provides
  evidence that electricity and magnetism are
  related. In addition, he discovers electrolysis
  and describes the conservation of energy law.
• 1799 - 1878 Joesph Henry's research on
  electromagnetic induction is performed at the
  same time as Faraday's. He constructs the first
  motor his work with electromagnets leads
  directly to the development of the telegraph.

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• 1873 James Clerk Maxwell performs important
  research in three areas color vision, molecular
  theory, and electromagnetic theory. The ideas
  underlying Maxwell's theories of electromagnetism
  describes the propagation of light waves in a
  vacuum.
• Electromagnetic interaction/force
• Unification
• Electricity Magnetism Light ?
  Electromagnetism

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• 1874 George Stoney develops a theory of the
  electron and estimates its mass.
• 1895 Wilhelm Röntgen discovers X rays.
• 1898 Marie and Pierre Curie separate radioactive
  elements.
• 1898 Joseph Thompson measures the electron, and
  puts forth his "plum-pudding" model of the atom
  -- that the atom is a slightly positive sphere
  with small, raisin-like negative electrons
  inside.
• - measure momentum and charge through deflection
  in magnetic field

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• 1900 Max Planck suggests that radiation is
  quantized (it comes in discrete amounts.)
• 1905 Albert Einstein, one of the few scientists
  to take Planck's ideas seriously, proposes a
  quantum of light (the photon) which behaves like
  a particle. Einstein's other theories explained
  the equivalence of mass and energy, the
  particle-wave duality of photons, the equivalence
  principle, and special relativity.
• - energy-mass equivalence
• 1909 Hans Geiger and Ernest Marsden, under the
  supervision of Ernest Rutherford, scatter alpha
  particles off a gold foil and observe large
  angles of scattering, suggesting that atoms have
  a small, dense, positively charged nucleus.
• 1911 Ernest Rutherford infers the nucleus as the
  result of the alpha-scattering experiment
  performed by Hans Geiger and Ernest Marsden.
• - scattering experiment

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• 1912 Albert Einstein explains the curvature of
  space-time.
• - curvature mimicking force
• 1913 Niels Bohr succeeds in constructing a theory
  of atomic structure based on quantum ideas.
• 1917 Friedmann realised that Einstein equations
  could describe an expanding universe. Allows
  (later called by Hoyle) Big Bang model of the
  universe.
• 1919 Ernest Rutherford finds the first evidence
  for a proton.
• 1921 James Chadwick and E.S. Bieler conclude that
  some strong force holds the nucleus together.
• - strong nuclear force
• 1923 Arthur Compton discovers the quantum
  (particle) nature of x rays, thus confirming
  photons as particles.
• 1924 Louis de Broglie proposes that matter has
  wave properties.
• 1925 (Jan) Wolfgang Pauli formulates the
  exclusion principle for electrons in an atom.
• 1925 (April) Walther Bothe and Hans Geiger
  demonstrate that energy and mass are conserved in
  atomic processes.
• 1926 Erwin Schroedinger develops wave mechanics,
  which describes the behavior of quantum systems
  for bosons. Max Born gives a probability
  interpretation of quantum mechanics. G.N. Lewis
  proposes the name "photon" for a light quantum.
• 1927 Certain materials had been observed to emit
  electrons (beta decay). Since both the atom and
  the nucleus have discrete energy levels, it is
  hard to see how electrons produced in transition
  could have a continuous spectrum (see 1930 for an
  answer.)

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• 1927 Werner Heisenberg formulates the uncertainty
  principle the more you know about a particle's
  energy, the less you know about the time of the
  energy (and vice versa.) The same uncertainty
  applies to momenta and coordinates.
• 1928 Paul Dirac combines quantum mechanics and
  special relativity to describe the electron.
• - basis for quantum electrodynamics contains
  spin and antiparticles
• 1929 Edwin Hubble showed that galaxies are moving
  away from us with a speed proportional to their
  distance
• 1930 Quantum mechanics and special relativity are
  well established. There are just three
  fundamental particles protons, electrons, and
  photons. Max Born, after learning of the Dirac
  equation, said, "Physics as we know it will be
  over in six months."
• 1930 Wolfgang Pauli suggests the neutrino to
  explain the continuous electron spectrum for beta
  decay.
• - neutrino chargeless, massless
• - proposal of new particle to protect
  conservation principle
• 1931 Paul Dirac realizes that the
  positively-charged particles required by his
  equation are new objects (he calls them
  "positrons"). They are exactly like electrons,
  but positively charged. This is the first example
  of antiparticles.
• 1931 James Chadwick discovers the neutron. The
  mechanisms of nuclear binding and decay become
  primary problems.
• - look for protons scattered by neutrals from
  a-scattering

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• 1930s Zwicky, Babcock require dark matter to
  explain galaxy dynamics.
• 1933-34 Enrico Fermi puts forth a theory of beta
  decay that introduces the weak interaction. This
  is the first theory to explicitly use neutrinos
  and particle flavor changes.
• - weak nuclear interaction
• 1933-34 Hideki Yukawa combines relativity and
  quantum theory to describe nuclear interactions
  by an exchange of new particles (mesons called
  "pions") between protons and neutrons. From the
  size of the nucleus, Yukawa concludes that the
  mass of the conjectured particles (mesons) is
  about 200 electron masses. This is the beginning
  of the meson theory of nuclear forces.
• - force as a result of particle exchange
• 1937 A particle of 200 electron masses is
  discovered in cosmic rays. While at first
  physicists thought it was Yukawa's pion, it was
  later discovered to be a muon.
• 1938 E.C.G. Stuckelberg observes that protons and
  neutrons do not decay into any combination of
  electrons, neutrinos, muons, or their
  antiparticles. The stability of the proton cannot
  be explained in terms of energy or charge
  conservation he proposes that heavy particles
  are independently conserved.
• 1941 C. Moller and Abraham Pais introduce the
  term "nucleon" as a generic term for protons and
  neutrons.

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• 1946-47 Physicists realize that the cosmic ray
  particle thought to be Yukawa's meson is instead
  a "muon," the first particle of the second
  generation of matter particles to be found. This
  discovery was completely unexpected -- I.I. Rabi
  comments "who ordered that?" The term "lepton" is
  introduced to describe objects that do not
  interact too strongly (electrons and muons are
  both leptons).
• 1947 A meson that does interact strongly is found
  in cosmic rays by Powell, and is determined to be
  the pion.
• 1947 Physicists develop procedures to calculate
  electromagnetic properties of electrons,
  positrons, and photons. Introduction of Feynman
  diagrams.
• - perturbative calculations
• 1948 The Berkeley synchro-cyclotron produces the
  first artificial pions.
• - accelerators
• 1949 Alpher and Hermann predict the cosmic
  microwave background radiation, interpreted as
  the faint afterglow of the intense radiation of a
  Hot Big Bang.

Berkeley cyclotron
Microwave background radiation
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First K meson observed (decay at point B)

• 1949 Enrico Fermi and C.N. Yang suggest that a
  pion is a composite structure of a nucleon and an
  anti-nucleon. This idea of composite particles is
  quite radical.
• 1949 Discovery of K via its decay.
• 1950 The neutral pion is discovered.
• 1951 Two new types of particles are discovered in
  cosmic rays. They are discovered by looking a
  V-like tracks and reconstructing the
  electrically-neutral object that must have
  decayed to produce the two charged objects that
  left the tracks. The particles were named the L0
  and the K0.
• 1952 Discovery of particle called delta there
  were four similar particles (D, D, D0, and
  D-.)
• 1952 Donald Glaser invents the bubble chamber.
  The Brookhaven Cosmotron, a 1.3 GeV accelerator,
  starts operation.
• 1953 The beginning of a "particle explosion" -- a
  true proliferation of particles.
• 1953 - 57 Scattering of electrons off nuclei
  reveals a charge density distribution inside
  protons, and even neutrons. Description of this
  electromagnetic structure of protons and neutrons
  suggests some kind of internal structure to these
  objects, though they are still regarded as
  fundamental particles.

Bubble chamber
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• 1953 Reines and Cowan discovers the neutrino by
  looking at products from inverse beta decay of
  neutrinos from reactor
• (anti)n p ? n e
• 1955 Davis shows that the neutrino is different
  from its antiparticle by searching for inverse
  beta decay in Chlorine-37 (to Argon-37) due to
  reactor (anti)neutrinos

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• 1954 C.N. Yang and Robert Mills develop a new
  class of theories called "gauge theories."
  Although not realized at the time, this type of
  theory now forms the basis of the Standard Model.
  
• 1957 Julian Schwinger writes a paper proposing
  unification of weak and electromagnetic
  interactions.
• 1957-59 Julian Schwinger, Sidney Bludman, and
  Sheldon Glashow, in separate papers, suggest that
  all weak interactions are mediated by charged
  heavy bosons, later called W and W-. Actually,
  it was Yukawa who first discussed boson exchange
  twenty years earlier, but he proposed the pion as
  the mediator of the weak force.
• 1961 As the number of known particles keep
  increasing, a mathematical classification scheme
  to organize the particles (the group SU(3)) helps
  physicists recognize patterns of particle types.
• - (gauge) symmetries
• 1962 Experiments verify that there are two
  distinct types of neutrinos (electron and muon
  neutrinos). This was earlier inferred from
  theoretical considerations.

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Baryon

• 1964 Murray Gell-Mann and George Zweig
  tentatively put forth the idea of quarks. They
  suggested that mesons (quark-antiquark) and
  baryons (quark-quark-quark) are composites of
  three types (flavours) of quarks or antiquarks,
  called up, down, or strange (u, d, s) with spin
  0.5 and electric charges 2/3, -1/3, -1/3,
  respectively (it turns out that this theory is
  not completely accurate). Since the charges had
  never been observed, the introduction of quarks
  was treated more as a mathematical explanation of
  flavor patterns of particle masses than as a
  postulate of actual physical object. Later
  theoretical and experimental developments allow
  us to now regard the quarks as real physical
  objects, even though they cannot be isolated.
• 1964 The W- (sss baryon) discovered through its
  decay products.

Meson
Helium atom
Discovery of the W-
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• 1964 Since leptons had a certain pattern, several
  papers suggested a fourth quark carrying another
  flavor to give a similar repeated pattern for the
  quarks, now seen as the generations of matter.
  Very few physicists took this suggestion
  seriously at the time. Sheldon Glashow and James
  Bjorken coin the term "charm" for the fourth (c)
  quark.
• 1965 Penzias and Wilson discovered a cosmic
  microwave background radiation

Penzias and Wilson and the horn antenna
Microwave background spectrum
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• 1965 O.W. Greenberg, M.Y. Han, and Yoichiro Nambu
  introduce the quark property of color charge. All
  observed hadrons are color neutral.
• ...1966... The quark model is accepted rather
  slowly because quarks hadn't been observed.
• 1967 Steven Weinberg and Abdus Salam separately
  propose a theory that unifies electromagnetic and
  weak interactions into the electroweak
  interaction. Their theory requires the existence
  of a neutral, weakly interacting boson (now
  called the Z0) that mediates a weak interaction
  that had not been observed at that time. They
  also predict an additional massive boson called
  the Higgs Boson that has not yet been observed.
• - spontaneous symmetry-breaking

Peter Higgs
Spontaneous symmetry-breaking (Higgs mechanism)
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The Higgs mechanism
Pictures courtesy CERN
Higgs field
A particle acquires mass in a Higgs field
Higgs boson
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• 1968-69 At the Stanford Linear Accelerator, in an
  experiment in which electrons are scattered off
  protons, the electrons appear to be bouncing off
  small hard cores inside the proton. James Bjorken
  and Richard Feynman analyze this data in terms of
  a model of constituent particles inside the
  proton (they didn't use the name "quark" for the
  constituents, even though this experiment
  provided evidence for quarks.)
• - substructure from scattering

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• 1970 Sheldon Glashow, John Iliopoulos, and
  Luciano Maiani recognize the critical importance
  of a fourth type of quark in the context of the
  Standard Model. A fourth quark allows a theory
  that has flavor-conserving Z0-mediated weak
  interactions but no flavor-changing ones.
• 1973 Donald Perkins, spurred by a prediction of
  the Standard Model, re-analyzes some old data
  from CERN and finds indications of weak
  interactions with no charge exchange (those due
  to a Z0 exchange.)
• 1973 A quantum field theory of strong interaction
  is formulated. This theory of quarks and gluons
  (now part of the Standard Model) is similar in
  structure to quantum electrodynamics (QED), but
  since strong interaction deals with color charge
  this theory is called quantum chromodynamics
  (QCD). Quarks are determined to be real
  particles, carrying a color charge. Gluons are
  massless quanta of the strong-interaction field.
  This strong interaction theory was first
  suggested by Harald Fritzsch and Murray
  Gell-Mann.
• 1973 David Politzer, David Gross, and Frank
  Wilczek discover that the color theory of the
  strong interaction has a special property, now
  called "asymptotic freedom." The property is
  necessary to describe the 1968-69 data on the
  substrate of the proton.
• 1974 In a summary talk for a conference, John
  Iliopoulos presents, for the first time in a
  single report, the view of physics now called
• the Standard Model.

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• 1974 (Nov.) Burton Richter and Samuel Ting,
  leading independent experiments, announce on the
  same day that they discovered the same new
  particle. Ting and his collaborators at
  Brookhaven called this particle the "J" particle,
  whereas Richter and his collaborators at SLAC
  called this particle the y particle. Since the
  discoveries are given equal weight, the particle
  is commonly known as the J/y particle. The J/y
  particle is a charm-anticharm meson.
• 1976 Gerson Goldhaber and Francois Pierre find
  the D0 meson (anti-up and charm quarks). The
  theoretical predictions agreed dramatically with
  the experimental results, offering support for
  the Standard Model.
• 1976 The tau lepton is discovered by Martin Perl
  and collaborators at SLAC. Since this lepton is
  the first recorded particle of the third
  generation, it is completely unexpected.

y? y p p- y ? e e-
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• 1977 Leon Lederman and his collaborators at
  Fermilab discover yet another quark (and its
  antiquark). This quark was called the "bottom"
  quark. Since physicists figured that quarks came
  in pairs, this discovery adds impetus to search
  for the sixth quark "top."

FERMILAB
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• 1978 Charles Prescott and Richard Taylor observe
  a Z0-mediated weak interaction in the scattering
  of polarized electrons from deuterium which shows
  a violation of parity conservation, as predicted
  by the Standard Model, confirming the theory's
  prediction.
• 1979 Strong evidence for a gluon radiated by the
  initial quark or antiquark if found at PETRA, a
  colliding beam facility at the DESY laboratory in
  Hamburg,

DESY
ee- ? q q
ee- ? q q g
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• 1983 The W and Z0 intermediate bosons demanded
  by the electroweak theory are observed by two
  experiments using the CERN synchrotron using
  techniques developed by Carlo Rubbia and Simon
  Van der Meer to collide protons and antiprotons.

7 km SPS ring
CERN
W ? e n
UA1 detector
First Z0
Pictures courtesy CERN
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• 1989 Experiments carried out in SLAC and CERN
  strongly suggest that there are three and only
  three generations of fundamental particles. This
  is inferred by showing that the Z0-boson lifetime
  is consistent only with the existence of exactly
  three very light (or massless) neutrinos.
• 1991 3 neutrinos confirmed by LEP

Courtesy CERN
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Pictures courtesy CERN
The 27 km LEP ring
The ALEPH detector
The L3 detector
The DELPHI detector
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Pictures courtesy CERN
ALEPH
An event observed by ALEPH
calorimetry
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• 1992 NASA's Cosmic Background Explorer satellite
  detected the first anisotropies in this
  background radiation. There are slight
  fluctuations in the temperature of the radiation,
  about one part in a hundred thousand, which may
  be the seeds from which galaxies formed

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• 1995 After eighteen years of searching at many
  accelerators, the CDF and D0 experiments at
  Fermilab discover the top quark at the unexpected
  mass of 175 GeV. No one understands why the mass
  is so different from the other five quarks.

CDF detector
D0 Collaboration
Top signature
Top event through electron signature
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Courtesy CERN
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Courtesy CERN
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Courtesy CERN
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Courtesy CERN
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Some Remaining Questions

• Generations
• Masses why the hierarchy where is the Higgs?
• More types of particles and forces to be
  discovered?
• Substructure?
• Further unification proton decay,
  supersymmetry, supergravity, Kaluza-Klein,
  superstrings, M theory
• Dark matter
• Flatness of the universe

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Indication of SUSY
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Some recent developments

• Neutrino masses
• 1994 First proclamation of possible neutrinos
  oscillations seen by LSND experiment
• 1995 Missing solar neutrinos confirmed by GALLEX
• 1998 Neutrino oscillations seen in LSND and
  Super-Kamiokande

Building a neutrino detector to look for missing
solar neurtinos in Homestake mines
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• Looking for neutrino oscillations at Kamiokande

A muon from a muon neutrino
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• Cosmological microwave anisotropy
• Density fluctuations very early
• Dark energy

Earliest galaxies (400-800 Myrs after big bang)
Hubble space telescope
WMAP
Earliest microwave anisotropies WMAP
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Dark energy
WMAP results
Supernova brightness vs redshift
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WMAP results

• WMAP data compared and combined with other
  diverse cosmic measurements (galaxy clustering,
  Lyman-alpha cloud clustering, supernovae, etc.)
• Universe is 13.7 billion years old, with a margin
  of error of close to 1.
• First stars ignited 200 million years after the
  Big Bang.
• Light in WMAP picture is from 379,000 years after
  the Big Bang.
• Content of the Universe
• 4 Atoms, 23 Cold Dark Matter, 73 Dark Energy.
• The data places new constraints on the Dark
  Energy. It seems more like a "cosmological
  constant" than a negative-pressure energy field
  called "quintessence". But quintessence is not
  ruled out.
• Fast moving neutrinos do not play any major role
  in the evolution of structure in the universe.
  They would have prevented the early clumping of
  gas in the universe, delaying the emergence of
  the first stars, in conflict with the new WMAP
  data.
• Expansion rate (Hubble constant) value Ho 71
  (km/sec)/Mpc (with a margin of error of about 5)
  
• New evidence for Inflation (in polarized signal)
• For the theory that fits our data, the Universe
  will expand forever. (The nature of the dark
  energy is still a mystery. If it changes with
  time, or if other unknown and unexpected things
  happen in the universe, this conclusion could
  change.)

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Possible Higgs?
Higgs pair decaying to four (anti)quarks

Courtesy CERN
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Ongoing and planned experiments
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RHIC
Looking for quark-gluon plasma
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WIMP detection
RAL-Imperial Collaboration
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HERA and TESLA
ZEUS Collaboration
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LHC
Constructing the CMS detector
LHC tunnel
Pictures courtesy CERN
Simulated Higgs on CMS
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ATLAS detector
Pictures courtesy CERN
digging
The collaboration 2000 scientists from 220
institutions from 39 countries from 6 continents
Simulated event
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• Hubble - deepest-ever view of the universe until
  ESA, together with NASA, launches the James Webb
  Space Telescope in 2011.

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Spin-offs

• Acceleration techniques
• Magnetics
• Superconductivity
• Detector technology
• Electronic data acquisition
• Data processing
• Computing and networking

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Courtesy CERN
accelerator
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Courtesy CERN
Superconducting magnet
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Courtesy CERN
Berners-Lee, originator of WWW, with first web
server
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Courtesy CERN
The DataGrid project
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Courtesy CERN
Largest HPD (hybrid photon detector), 10 cm
diameter
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Courtesy CERN
Fibreoptics
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Courtesy CERN
Silicon microstrip detector
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Courtesy CERN
Farming out computing on LINUX clusters
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Courtesy CERN
Superconducting strands
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How Malaysia can be a significant player in big
science by 2020
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• Basic sciences drive the development of science
  and technology
• Development in basic sciences which generate
  domestic technology required for competitiveness
  in a globalised era

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• Current level of science in Malaysia inadequate
• Malaysia should be advanced in science and
  technology by 2020 thus be a significant player
  in Big Science including high energy physics

• Rationale for Malaysia to enter the league of Big
  Science nations
• Strategic advantage scientific cooperation and
  leadership
• Scientific advantage civilisational wish,
  popularisation of science, science and technology
  transfer
• Technological advantage rapid technology
  development through spin-offs

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• PROPOSED TIMETABLE FOR MALAYSIAN INVOLVEMENT
• Initial steps have to be started immediately
• Human resource with specialized skills have to be
  developed
• Start by joining collaboration in ongoing
  experiments
• Subsequent involvement in internation experiments
  currently being planned

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Immediate actions to be taken

• Commitment from government for high energy
  physics to guarantee continuing funding, etc
• Human resource development through gradually
  increasing involvement in existing experiments
  from (14) to 10 (2005) to 20 (2010)
• Fund allocation
• Organization collaboration between domestic
  institutions central coordinating institute (?
  MINT ?)