Question

(a) Show that, for large Z and A, the energy released when a nucleus (ZA) emits an α particle is given by where B(24) is the binding energy of the α particle, 28.30 MeV, and η =k-1)" + (-1)"/2 (b) The isotopes 17 Ag of silver and Au of gold are the only naturally occurring ones. Discuss the stability of these nuclides in light of the expression for Qa you obtained in (a) CONTINUED ON NEXT PAGE The nuclide 200Cm (which is 0+) decays to 2 Pu almost 100% of the time, but it can decay to a variety of 4 Pu states: the 0' ground state (Q 5.902 Me V) with branching fraction of 76.7%, and to the following excited states given by their spin- parity, branching fraction, and energy above the ground state in MeV: (2", 23.3%, 0.043), (4°, 0.023%, 0.142), (6", 0.0036%, 0.294). (a) Draw the level diagram for these processes. (b) Use the Geiger-Nuttall relation In ω= C-DZ/Q1/2 , with C= 132.8, D-397 MeV1/2, Q in MeV, and ω in s-1 to compute the mean life of Cm. (c) Use the same values of C and D to compute the α decay rate for the transition to the 6", state, and compare it to the rate given by the branching fraction and the result of (b). Suggest an explanation for the discrepancy

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Answer 1

Date 2-2

t B 2. 드283-4 3 (1) (167)

Page УЗ 3(12) Y3 2 (112)2 112) -19.0 28.8 쿠) ニぐ. ISI Meal