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Closed Access item Quadrupole deformed and octupole collective bands in Ra-228

Authors:Gulda, K.
Mach, H.
Aas, A. J.
García Borge, María José
Burke, D. G.
Fogelberg, B.
Gietz, H.
Grant, I. S.
Hagebø, E.
Hill, P.
Hoff, P.
Kaffrell, N.
Kurcewicz, W.
Lindroth, A.
Løvhøiden, G.
Martínez, T.
Mattsson, S.
Naumann, R. A.
Nybø, K.
Nyman, G.
Rubio, Berta
Sánchez-Vega, M.
Taín, José Luis
Taylor, R. B. E.
Tengblad, Olof
Thorsteinsen, T. F.
Keywords:Radioactivity Fr-228, [from Th-232(p,4pln) and U-238(p,6p5n)], Measured E-e, I(ce), T-1/2, βγγ(t), γγ coincidences, Ra-228, Deduced ICC, Multipolarities, I-π, Rotational bands, B(XL), Ge, Si(Li), Plastic, BaF2 detectors, Mini-orange spectrometer, [PACS] Properties of nuclei; nuclear energy levels, [PACS] Electromagnetic transitions, [PACS] γ transitions and level energies, [PACS] Internal conversion and extranuclear effects (including Auger electrons and internal bremsstrahlung)
Issue Date:15-Jun-1998
Citation:Nuclear Physics A 636(1): 28-46 (1998)
Abstract:Spins and parities for collective states in Ra-228 have been determined from conversion electron measurements with a mini-orange β spectrometer. The fast-timing βγγ(t) method has been used to measure lifetimes of T(1/2) = 550(20) ps and 181(3) ps for the 2(1)(+) and 4(1)(+) members of the K = 0(+) band, and T(1/2) ≤ 7 ps and ≤ 6 ps for the 1(1)(-) and 3(1)(-) members of the K = 0(-) band, respectively. The quadrupole moments, Q(0), deduced from the B(E2;2(1)(+) --> 0(1)(+)) and B(E2;4(1)(+) -->2(1)(+)) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(EI) rates of ≥ 4 x 10(-4) e(2)fm(2), which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for Ra-228. The new results are consistent with the B(E1) rates recently measured for the neighbouring Ra-227 and reveal octupole correlations in Ra-228.
Description:19 pages, 4 tables, 4 figures.-- PACS nrs.: 21.10.-k; 23.20.-g; 23.20.Lv; 23.20.Nx.
Publisher version (URL):http://dx.doi.org/10.1016/S0375-9474(98)00191-2
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