Problem

{}^7\text{Li}

target is bombarded with a proton beam current of

10^{-4} \text{ A}

for 1 hour to produce

{}^7\text{Be}

of activity

1.8 \times 10^8

disintegrations per second. Assuming that one

{}^7\text{Be}

radioactive nucleus is produced by bombarding 1000 protons, determine its half-life.