Question

alpha decay tne menes valy widuery, Wnclcer the emitted alpha particles vary little (3 marks) The following expression holds for the half-life of an alpha emitter: (b) where C and D are (approximately) constant and D4 if Ea is in units of MeV Use this formula to calcuiate the ratio of the half-lives of Ra (a 5.685 MeV) and Ra (Ea 7.453 MeV). Compare your result with the ratio of the experimentally observed half-lives for 3 Ra (r 3.66 days) and 20Ra t 18 ms). (2 marks) (c) Xe has a 3/2t ground state, and the energies, spins and parities of the first three excited states of Xe are 1/2t at 0.080 MeV, 11/2 at 0.164 Me V, and 9/2 at 0.341 MeV. The three gamma ray transitions between these states are 9/2~-, 1 1/2-г 3/2+ and 1/2 3/2+. (i) Determine the dominant multipole for each of these three transitions. (3 marks) (ii) The 11/2 state is isomeric: briefly state what is meant by this and explain why (ii) The excited state at 0.365 MeV decays to the 1/2t state via an E2 transition. (1 mark) this is the case. (1 mark) Determine the most likely spin and parity of this excited state.

Answer 1

2 1h 2. Ratw 224 89 Ra 1.314 X lo ะ 7.153

thioulic a valut hu lt attu o du At kłtu 剛toit, r.eu d Atla It

and OC to