Question

Many radioisotopes have important industrial, medical, and research applications. One such radioisotope is 60Co, which has a half-life of 5.2 yr and decays by the emission of a beta particle (energy 0.31 MeV) and two gamma photons (energies 1.17 MeV and 1.33 MeV). A scientist wishes to prepare a 60Co sealed source that will have an activity of at least 10 Ci after 30 months of use. What is the minimum initial mass of 60Co required?

Answer 1

You are given the half life of an isoptope which is 5.2yr and the numer of days that it will decay which is 30 months. You are required to find the initial mass of the isotope.

An = A0*exptaveln2/t1/2
30 = A0 exp^(30/12 * ln2/5.2yr)
A0 = 21.5grams