0000000000131976
AUTHOR
M. Cromaz
Stable triaxiality at the highest spins in138Ndand139Nd
The nuclei ${}^{138}\mathrm{Nd}$ and ${}^{139}\mathrm{Nd}$ have been studied at very high spins via the ${}^{48}\mathrm{Ca}{+}^{94}\mathrm{Zr}$ reaction. Several new rotational bands were observed, four in ${}^{138}\mathrm{Nd}$ and two in ${}^{139}\mathrm{Nd}.$ The ${J}^{(2)}$ moments of inertia calculated from the observed $\ensuremath{\gamma}$-ray energies are very small and almost constant, indicating that these bands are triaxial. Cranked Nilsson-Strutinsky calculations reproduce the general behavior of the bands, supporting this interpretation and suggesting an approximately constant $\ensuremath{\gamma}$ value of $\ensuremath{\sim}+35\ifmmode^\circ\else\textdegree\fi{}$ over a large s…
Evidence for isovector neutron-proton pairing from high-spin states inN=Z74Rb
High-spin states in the odd-odd N=Z nucleus Rb-74(37)37 were studied using the Ca-40(Ca-40,alphanp) reaction. A previously observed odd-spin T=0 band has been extended to I-pi=(31(+)) and an even-spin T=0 band has been observed for the first time to I-pi=(22(+)); both have a pi(g(9/2))circle timesnu(g(9/2)) structure. A strongly coupled low-spin T=0,K=3 band has been interpreted as being based upon a pi[312]3/2 circle timesnu[312]3/2 configuration. Cranked relativistic Hartree-Bogoliubov calculations, which are corrected for the t=1 np-pair field by restoring isospin symmetry, reproduce the observed spectrum. These new results provide evidence for the existence of an isovector pair field th…
Isomers and high-spin structures in the N=81 isotones Xe135 and Ba137
The high-spin structures of the N = 81 isotones 135Xe and 137Ba are investigated after multinucleontransfer (MNT) and fusion-evaporation reactions. Both nuclei are populated in (i) 136Xe+238U and (ii) 136Xe+208Pb MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii), in the 136Xe+198Pt MNT reaction employing the -ray array GAMMASPHERE in combination with the gas detector array Chico, and (iv) via a 11B+130Te fusion-evaporation reaction. The high-spin level schemes of 135Xe and 137Ba are considerably extended to higher energies. The 2058-keV (19=2 ) state in 135Xe is identified as an isomer, completing the systema…
High-spin structures in Xe132 and Xe133 and evidence for isomers along the N=79 isotones
Author(s): Vogt, A; Siciliano, M; Birkenbach, B; Reiter, P; Hadynska-Klȩk, K; Wheldon, C; Valiente-Dobon, JJ; Teruya, E; Yoshinaga, N; Arnswald, K; Bazzacco, D; Blazhev, A; Bracco, A; Bruyneel, B; Chakrawarthy, RS; Chapman, R; Cline, D; Corradi, L; Crespi, FCL; Cromaz, M; De Angelis, G; Eberth, J; Fallon, P; Farnea, E; Fioretto, E; Fransen, C; Freeman, SJ; Fu, B; Gadea, A; Gelletly, W; Giaz, A; Gorgen, A; Gottardo, A; Hayes, AB; Hess, H; Hetzenegger, R; Hirsch, R; Hua, H; John, PR; Jolie, J; Jungclaus, A; Karayonchev, V; Kaya, L; Korten, W; Lee, IY; Leoni, S; Liang, X; Lunardi, S; MacChiavelli, AO; Menegazzo, R; Mengoni, D; Michelagnoli, C; Mijatovic, T; Montagnoli, G; Montanari, D; Muller-…
Shears Mechanism in theA∼110Region
Lifetimes of states in a rotational-like $M1$ band in ${}^{110}\mathrm{Cd}$ have been determined through a Doppler-shift attenuation method measurement performed with the Gammasphere array. The deduced $B(M1)$ values, which agree well with the predictions of the tilted axis cranking model, clearly confirm that it has the character of a shears band. Using a semiclassical scheme of the coupling of two long $j$ vectors we deduce information on the strength and form of the effective interaction between the constituent nucleons. These results are the first definitive evidence of the shears mechanism and ``magnetic rotation'' in this mass region.
High-spin structure of Xe134
A. Vogt et al. ; 12 págs.; 9 figs.; 1 tab.
Decay and Fission Hindrance of Two- and Four-QuasiparticleKIsomers inRf254
Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) μs have been discovered in the heavy ^{254}Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K^{π}=8^{-}, ν^{2}(7/2^{+}[624],9/2^{-}[734]) two-quasineutron and the K^{π}=16^{+}, 8^{-}ν^{2}(7/2^{+}[624],9/2^{-}[734])⊗8^{-}π^{2}(7/2^{-}[514],9/2^{+}[624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N=150 isotones. …
Shears mechanism in109Cd
Lifetimes of high-spin states in two $\ensuremath{\Delta}I=1$ bands and one $\ensuremath{\Delta}I=2$ band in ${}^{109}\mathrm{Cd}$ have been measured using the Doppler shift attenuation method in an experiment performed using the ${}^{96}\mathrm{Zr}{(}^{18}\mathrm{O},5n)$ reaction with the GAMMASPHERE array. Experimental total angular momenta and reduced transition strengths for both $\ensuremath{\Delta}I=1$ bands were compared with tilted axis cranking (shears mechanism) predictions and the $\ensuremath{\Delta}I=2$ band with principal axis cranking predictions, based on configurations involving two proton ${g}_{9/2}$ holes and one or three valence quasineutrons from the ${h}_{11/2}$ and mi…