Decays to by positron emission and by electron capture

PHYSICS · Multi-part · Fermi University Physics · Nuclear Physics · Radioactivity and decay modes · Radioactivity and decay modes

The Nucleus Resolved, Ch Beta decay: Fermi's theory, parity violation and the double beta modes

Problem

^{18}\mathrm{F}

decays to

^{18}\mathrm{O}

by positron emission and by electron capture. The atomic mass excesses are

\Delta(^{18}\mathrm{F}) = +0.873\,\mathrm{MeV}

and

\Delta(^{18}\mathrm{O}) = -0.782\,\mathrm{MeV}

. ((a)) Calculate

Q_{\beta^+}

, stating explicitly how the electron masses are counted. ((b)) Calculate

Q_{EC}

for capture from a neutral

^{18}\mathrm{F}

atom, ignoring the atomic binding energy of the captured electron.