Mississippi students

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Mississippi students at CERN
Cosmic Ray Lecture-Demo
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The Particle Journey

• Greeks and others believe the earth and heavens
  were
• linked by four elements of nature earth, air,
  water and fire.
• Much of science was utilitarian, alchemy,
  astrology !
• Advances came by invention, discovery, accident.

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Atomism or not!

• All the objects in the universe are composed of
  very
• small, indestructible building blocks.
• In the late fifth century B.C. Democritus and
  Leucippus
• taught that the hidden substance in all physical
  objects
• consists of different arrangements of 1) atoms
  and 2) void.

• Aristotle asserted that the elements of fire,
  air, earth, and water were not made of atoms, but
  were continuous. 330 B.C.

Greek stamp honoring Democritus and his modern
significance.
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Spectacles - 13th century

• Assyrians first realized that glass spheres
  could be
• used as magnifying devices circa B.C./A.D.
• Probably invented anonymously and developed
• over a period of time- Vikings, Italians,
  Germans, etc.
• Allowed one to see things in more detail!

Italy circa 1352
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Telescope

• The telescope was unveiled in the Netherlands
• in October 1608!
• Galileo made the instrument famous. He
  constructed
• a 20-powered telescope in 1609 which was able to
  see
• Jupiter's moons - an event of major enlightenment!

"O telescope, instrument of much knowledge,
more precious than any sceptre! Is not he who
hold thee in his hand made king and lord of the
works of God?" - Johannes Kepler
Johannes Hevelius observing with one of his
telescopes.
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Microscope - 1662

• In 1662 Robert Hooke was named Curator of
  Experiments
• of the newly formed Royal Society of London.
• Hooke devised the compound microscope and
  illumination
• system and used it in his demonstrations at the
  Royal
• Society's meetings.
• He displayed plant cells! in a slice of cork
  (below).

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Microscope -1668

• The father of microscopy, Anton van Leeuwenhoek
• of Holland, started as an apprentice in a dry
  goods store
• where magnifying glasses were used to count the
  threads
• in cloth.
• He was the first to see and describe bacteria,
  yeast plants,
• the teeming life in a drop of water, and the
  circulation of
• blood corpuscles in capillaries.

" I have thought it my duty to put down my
discovery on paper, so that all ingenious people
might be informed thereof' .
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Modern Electricity

• Benjamin Franklin and others conducted extensive
• research on electricity in the 18th century.
• Alessandro Volta perfected a chemical battery.
• Two types of charges exist positive() and
  negative (-).
• Like charges repel, Unlike charges attract !

Volta
Volta's Chemical Battery
- - -
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Periodic Table of the Elements

• IN 1869 Russian chemist Dmitri Mendeleev
  organized the
• known elements in to a table to illustrate
  recurring ("periodic")
• properties- Z charge, A Atomic Weight

AXZ
1.0079H1
12.0112C6
4.0026He2
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Electron Tubes - Particle Accelerator

• 1850's experimenters began passing electricity
  through evacuated and gas filled tubes from
  negative to positive electrode.
• James Crookes developed a series of tubes and
  observed cathode (-) rays!
• 1897, JJ Thompson measured the mass of the rays
  to be very small compared to an atom -gt electrons!

Crooke's Tube
Thompson's 2nd experiment
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Rutherford Atom

• In 1911 Rutherford experimented with alpha
  particles and gold
• foil and discovers that atoms have a small
  positive nucleus
• made of protons and outer negative cloud -
  electrons.

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Building an Hydrogen Atom
p
H atom
E lt12.6 eV
Electro-magnetic Force
e-
photon or gamma ray
force carrier
p
p
E gt13.6 eV
scattering
e-
e-
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Rutherford Scattering revisited

• By scattering experiments one can study the
  physical
• properties of the scattering particles and the
  internal forces.
• -Properties mass, charge, intrinsic magnetism
  

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Discovery of the Neutron

• In 1932 James Chadwick discovered a heavy
  neutral
• particle, the neutron.

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Nuclear Binding Force

• If the nucleus is made of protons, why do the
  positive
• charges stick together?

1H1
p
Hydrogen
p
p
nuclear binding force
gluon
Does not bind!
force carrier
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The Weak Force and the Neutrino

• In radioactive beta decay neutrons transmute to
  protons
• with the emission of an electron.
• In 1930 W. Pauli proposed that a 3rd invisible
  particle called
• the neutrino was emitted, consistent with
  experiment.

?
n
p
e-
Never observed!
Pauli's solution, the neutrino.
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Anti Matter

• In 1928 Paul Dirac proposed that every particle
  should have an associated anti-particle with
  reversed electric charge.
• In 1936, at age 31, Carl Anderson became the
  second youngest Nobel laureate for his discovery
  of antimatter when he observed positrons in a
  cloud chamber.

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Quarks

• Scattering experiments in the 50's and 60's gave
  evidence that protons and neutrons were made of
  fractionally charges particles called quarks.
• Today we believe there are 6 quarks.
• up charm top q2/3e
• down strange bottom q-1/3e
• A proton is then two ups and a down.

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EM
Todays Particle Picture
Strong
Weak
Gravity
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STANDARD MODEL
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The Higgs Boson

• Why do particles have mass?
• In the 1960's Peter Higgs proposed a particle
  named the
• the higgs boson which gives mass to all
  particles.

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(1) Higgs to Gamma Gamma
H ? g ?g
photon
t
t
top loop
t
t
photon
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(2) Higgs to 4 Leptons
H ? l l- l l
proton
l
Z
gluon
top
l-
H
l l-
gluon
top
Z
proton
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(3) Higgs to 2 Leptons 2 jets
H ? l l- j j
proton
l
Z
gluon
top
l-
H
q-jet q-jet
gluon
top
Z
proton
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(4) Higgs to 2 Leptons 2 jets
H ? j j j j
proton
q-jet q-jet
Z
gluon
top
H
q-jet q-jet
gluon
top
Z
proton
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(5) Black Hole to 4 leptons
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CMS DETECTOR
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CMS SLICE