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Homework Statement
Calculate the Q-value for the electron capture beta decay of Kr-81
(Answer in MeV, correct to 6 significant figures)
Atomic Masses (amu)
Kr-81 = 80.916592(3)
Br-81 = 80.916291(3)
proton 1.00727647
neutron 1.00866501
electron 0.0005485803
Homework Equations
Q = ∑mic2-∑mfc2
Electron Capture = ZX +e_ ---> Y+ neutrino
The Attempt at a Solution
Q = (80.916592 + 0.0005485803) - 80.916291
= 0.00084958029 * 931.5020
= 0.7913857 MeV
I found a Q value of .280801 Mev online. Not sure why I'm off by so much...
Q = 80.916592 - 80.916291 = 0.00030099999
Q = 0.00030099999 * 931.5020cMeV
= 0.28038209268
= 0.2803821 Mev (correct to 6 sig figs)
Seems better, but I've calculated this using the atomic masses and not the nuclear masses...
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