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Physical and Applicative Overview Joey Goodknight Physics 129 October 21, 2010
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Getting and Getting Rid of Them
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Basic Physical Mechanisms Antimatter is Everywhere Too Many Electrons!
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How and Why the Positron?
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1 gram of anti-p+ 2 X 10 14 Joules 4 “Little Boy”s (Hiroshima) 2 “Fat Man”s (Nagasaki) $25,000,000,000.00 (2009 Nasa Study) ~GDP of Yemen Admittedly only 1/20 of US defense Spending ~Yearly Nuclear Weapons Spending (1998 ) Containment Unrealistic past 10 12 atoms From Space: Classic “Doomsday Theory” Tungaska Event
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Sorry, Back to e+/e-…
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EM Phenomenon 3 main methods: γ e + + e - γ + γ e + + e - Decay Other Possibilities?
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EE Conservation E=h υ = ~ m e c 2 λ ~1 femtometer υ ~10 23 Hz Well past gamma rays PP Conservation Restricts Diagrams LLeast Expected Femtosecond 800nm focus
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matter+anti-matter “Nothing” Much simpler than Prod. P Conservation Positronium Bound state L=0, annihilation!
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Dirac 1929 Carl Anderson 1932 under Millikan Cloud Chamber Tracks γ 208 Tl 1936 Nobel
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They’re All Around Us!
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+q -q’ +q’ Goop, full of dipoles
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+q -q E=?
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Vacuum Photons Create Virtual Pairs Shield Charge Vacuum Dielectric QED Triumph spin 1997 Confirmation
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Seein’ inside you
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Weak Force Decay 11 C, 40 K, 13 N, 18 F etc.
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e+e- γ γ Photons Come out at 180 degrees to each other Complex Processing Density Map of Tracer
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Always a Friend of Solid State Physicists
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e+ γ γ Positron Source Na, usually γ Scan Material Correlate emission with annihilation Generate map of open volume defects Gets trapped Live longer Defects are what make many semiconductors cool
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