(a) The first excited state of lies at above the ground state and decays by an…
PHYSICS · Subjective · Fermi University Physics · Nuclear Physics · Radioactivity and decay modes · Radioactivity and decay modes
The Nucleus Resolved, Ch Gamma decay: multipoles, isomers, internal conversion and the Mossbauer line
Problem
(a) The first excited 2+ state of 114Cd lies at Eγ=0.558MeV above the 0+ ground state and decays by an E2 transition with measured photon partial mean life τγ=18.3ps. Using the Weisskopf estimate λW(E2)=7.3×107A4/3Eγ5s−1 (with Eγ in MeV), express the measured strength in Weisskopf units and say whether the transition is collective or single-particle. (b) A γ-γ cascade following electron capture in an even-even nucleus is fitted to W(θ)=1+A2P2(cosθ)+A4P4(cosθ) with measured coefficients A2=0.357, A4=1.141. Four candidate spin sequences, each with both steps of definite multipolarity, predict the ratio W(180∘)/W(90∘) as follows: 0+→2+→0+ (E2,E2): 2.00; 2+→2+→0+ (pure M1, then E2): 1.43; 4+→2+→0+ (E2,E2): 1.17; 3+→2+→0+ (dipole, then E2): 0.90. Compute the measured ratio using P2(0)=−21, P2(1)=1, P4(0)=83, P4(1)=1, and identify the spin sequence.