Problem 6.284

The yield of a nuclear reaction producing radionuclides may be described in two ways: either by the ratio $w$ of the number of nuclear reactions to the number of bombarding particles, or by the quantity $k$, the ratio of the activity of the formed radionuclide to the number of bombarding particles, Find: (a) the half-life of the formed radionuclide, assuming $w$ and $k$ to be known: (b) the yield $w$ of the reaction $L i^{7}(p, n) B e^{7}$ if after irradiation of a lithium target by a beam of protons (over $t=2.0$ hours and with beam current $I=10 \mu \mathrm{A}$ ) the activity of $\mathrm{Be}^{7}$ became equal to $A=$ $=1.35 \cdot 10^{8}$ dis/s and its half-life to $T=53$ days.