ANTIPARTICLES

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ANTIPARTICLES

• Prep by Beste KORUTLU

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OUTLINE

• MATTER ANTI MATTER
• DISCOVERY OF ANTIMATTER
• DIRACS THEORY OF ANTIMATTER
• FEYNMANS THEORY OF ANTIMATTER
• 1930- 1995

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Matter and Antimatter

• MATTER
• All quarks
• All negatively charged leptons.
• Left handed neutrinos.

• ANTIMATTER
• Antiquarks
• Positively charged leptons
• Right-handed neutrinos.

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Matter/Anti-Matter Asymmetry

• Pair production
• Annihilation
• Q anti Q photon photon

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The Discovery of Antimatter

• In 1932 there were three known elementary
  particles
• Electron
• Positron
• Neutron

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Then Carl Anderson discovered a new one.
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The new particle that Anderson discovered

• The mass equals the mass of the electron.
• The charge has the same magnitude as the
  electron's charge, but is positive
• The particle is always created in pairs with
  electrons.
• When this particle collides with an electron,
  both annihilate

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Dirac's Theory of Antimatter

• Why the energy is always a positive number?
• Why don't we observe these negative energy
  electrons?

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A Hindu story

• A fish went to the Queen fish and asked "I
  have always heard about the sea, but what is the
  sea? Where is it?"
• The Queen fish replied "You live, move, and
  have your being in the sea. The sea is within you
  and without you, and you are made of sea and you
  will end in sea. The sea surrounds you as your
  own being.

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Feynman's Theory of Antimatter

• No creation
• No annihilation
• Change of direction of moving particles from past
  to future, or from future to past

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"Day and Night" by M. C. Escher
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After 22 Years

• In 1930, Ernest Lawrence had invented the
  cyclotron
• In 1954, Lawrence built the Bevatron at Berkeley,
  California
• In October 1955 the big news hit the front page
  of the New York Times "New Atom Particle Found
  Termed a Negative Proton".

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1965 Antinuclei

• Only a year later, a second team working at the
  Bevatron (B. Cork, O. Piccione, W. Wenzel and G.
  Lambertson) announced the discovery of the
  antineutron.
• In 1965 with the observation of the antideuteron,
  a nucleus of antimatter made out of an antiproton
  plus an antineutron

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1995 from antiparticles to antimatter

• In fact the answer was only revealed quite
  recently in Low Energy Antiproton Ring (LEAR).
• Contrary to an accelerator, LEAR actually "slowed
  down" antiprotons.
• Physicists could then try to force a positron (or
  antielectron) to stick to an antiproton

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How do you distinguish a neutron from an
antineutron?

• Neutrons are made of quarks, and antineutrons are
  made of antiquarks. Quarks and antiquarks have
  opposite charges, even though they sum up to zero
  in both cases.

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What about antiphotons?

• Photons have zero charge and do not contain
  inside objects that are charged, so a photon can
  not be distinguished from an antiphoton. Photon
  and antiphotons are the same thing, i.e. the
  photon is its own antiparticle.

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CONCLUSION ?

• So there you go ... now you have a recipe for
  how to convert yourself into a pure photon
  energy you just need to create anti-you and then
  have a date with 'it'.

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THANK YOU