Pair Annihilation and Production Physical and Applicative Overview Joey Goodknight Physics 129 October 21, 2010
Feb 26, 2016
Pair Annihilation and Production
Pair Annihilation and ProductionPhysical and Applicative Overview
Joey GoodknightPhysics 129October 21, 20101e+/e-Getting and Getting Rid of Them2GoalsBasic Physical MechanismsAntimatter is EverywhereToo Many Electrons!3History, Motivation and MechanismsHow and Why the Positron?4Antimatter: The Publics View5Reality Check1 gram of anti-p+2 X 1014 Joules4 Little Boys (Hiroshima)2 Fat Mans (Nagasaki)$25,000,000,000.00 (2009 Nasa Study)~GDP of YemenAdmittedly only 1/20 of US defense Spending~Yearly Nuclear Weapons Spending (1998 ) Containment Unrealistic past 1012 atomsFrom Space: Classic Doomsday TheoryTungaska Event
6Sorry, Back to e+/e-7Pair Production?EM Phenomenon3 main methods: e+ + e- + e+ + e-DecayOther Possibilities?
8ConditionsE ConservationE=h=~mec2~1 femtometer ~1023 Hz Well past gamma raysP ConservationRestricts DiagramsLeast ExpectedFemtosecond 800nm focus
9Pair Annihilation?matter+anti-matterNothingMuch simpler than Prod.P ConservationPositroniumBound stateL=0, annihilation!
10History: First Pair ProductionDirac1929Carl Anderson1932 under MillikanCloud Chamber Tracks 208Tl1936 Nobel
11Nifty ApplicationsTheyre All Around Us!12What if qeqe?13+q-q+qGoop, full of dipoles14+q-q
E=?E=?15Vacuum PolarizabilityVacuum PhotonsCreate Virtual PairsShield ChargeVacuumDielectricQED Triumphspin1997 Confirmation
16Positron Emission TomographySeein inside you17Positron (+) DecayWeak Force Decay11C, 40K, 13N, 18F etc.
18PET: How it Works
e+
e-
Photons Come out at 180 degrees to each otherComplex ProcessingDensity Map of Tracer19PALSAlways a Friend of Solid State Physicists20e+Positron SourceNa, usuallyScan MaterialCorrelate emission with annihilationGenerate map of open volume defectsGets trappedLive longerDefects are what make many semiconductors cool21Hawking Radiation22
Black hole, kicks 23Thank You24