On the decay of the J = 11/2, T1/2 = 38.9 h isomer in 133Ba: search for the E5 transition and verification of the EC branch

P Granholm (1, 2) , T Lönnroth (1) , J Suhonen (3) , J Bergman (4) , K-M Källman (1) , J-O Lill (1, 4) , M Norrby (1) , E Ydrefors (3) , P Tikkanen (5)

1 Department of Physics
2 Telecommunication and e-Business
3 JYU - Department of Physics [Jyväskylä Univ]
4 Turku PET Centre
5 JYFL-ACCLAB - Accelerator Laboratory

This paper presents a search for the competing 11/2 − → 1/2 + E5 branch to the main 11/2 − → 3/2 + M4 transition from the T 1/2 = 39 h, J π = 11/2 − isomeric state in 133 Ba. An upper limit of 1.8 * 10 −5 could be established for the E5/M4 intensity ratio. In addition a long-standing controversy in the EC-decay of the same isomer was resolved: only one EC branch to the 11/2 + state in 133 Cs was observed. The shell-model structures of the involved states in 133 Ba and 133 Cs were studied with the microscopic quasiparticle-phonon model (MQPM). Good agreement with the decay rates B(λ) was obtained. In particular, the B(M4) value is well reproduced and further only one low-lying 11/2 state could be identified in the latter nuclide, supporting the experimental results.

Mots clés: 23.20.-g

Mots clés: 23.35.+g; 21.60.-n; 21.60.Cs; 23.40.-s

P Granholm, T Lönnroth, J Suhonen, J Bergman, K-M Källman, et al.. On the decay of the J = 11/2, T1/2 = 38.9 h isomer in 133Ba: search for the E5 transition and verification of the EC branch. Journal of Physics G: Nuclear and Particle Physics, 2011, 38 (1), pp.15101. ⟨10.1088/0954-3899/38/1/015101⟩. ⟨hal-00600868⟩