Question

(Figure 1) shows the decay scheme for 137Cs, which has two possible beta decay modes. The first, labeled β1, is a decay directly to the ground state of 137Ba. The second beta decay (β2) is to an excited state 137Ba∗. This excited state subsequently undergoes gamma decay to the ground state. In beta decay, the maximum possible energy of the emitted beta particle is equal to the difference in energy between the initial and final states of the nucleus. The maximum energy of β2 has been measured to be 0.5120 MeV. Atomic mass of 137Ba is 136.9058274 u, atomic mass of 137Cs is 136.9070895 u.

What is the maximum energy of the beta particle β1? Express your answer in megaelectron volts.

What is the energy of the gamma ray? Express your answer in megaelectron volts.

137 Cs β2 βι "У 137Ba

Answer 1

134 Cs 134Lq ass8q Mass , 0. 66 46 46/s Mev En