EES 0836 Lecture Notes - Lecture 5: The Physicists, Strontium-90, Positron
3 Apr 2016
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Lecture - 5: radioactivity, any time a nucleus spontaneously emits a particle . Electron through beta ( -) decay: increase z by 1; decrease n by 1; a remains the same. Positron (anti-electron) through beta ( +) decay: decrease z by 1; increase n by 1; a remains the same. Alpha ((cid:1)) particle (4he nucleus: decrease z by 2; decrease n by 2; decrease a by 4. Gamma ((cid:1)) ray (high-energy photon of light: z, n, a unchanged (stays the same nucleus, just loses energy, we say it underwent a radioactive transformation, certain isotopes of nuclei are radioactively unstable. They will eventually change flavor by a radioactive particle emission. Not 100% efficient at detection, but representative of rate: have three sources: 14c (carbon-14) with half life of 5730 years (to 14n: about 4200 - decays per second in this sample, corresponds to 25 ng, or 1015 particles.
