Matter-Antimatter
Annihilation
Contact person: K. Kolsky and A. Frenkel
Location: Medical Facility, Bldg. 801
Duration: several hours
Description:
The processes of electron-positron annihilation into
photon pairs and of pair creation by photons are of interest both
theoretically and experimentally. Not only they can shed light on flavor
of quarks and anti-quarks that can be created at high enough energies
during a billionth of a billionth of a billionth of a second, they give
rise to imagination of cosmologists who study black holes and even time
travel...
(Copyright:
http://www.schoolscience.co.uk/content/4/physics/particles/particlesmodel4b.html)
Students will
verify the Einstein's
famous equation, E = mc2 and observe matter-antimatter
annihilation using the positron
beta-decay 22Na source.Positrons
slow down in a material to the point where they annihilate with electrons
producing two gamma quanta, each with 511 keV and traveling in opposite
direction. This
energy is equal to the electron rest mass.
Students measure this energy, taking into account the Doppler
effect, by using the Germanium gamma-ray spectrometer,
and obtain the rest mass of electron by using the E = mc2
equation.
