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The transitional nuclei Ba134 and Ba133 are investigated after multinucleon transfer employing the high-resolution Advanced GAmma Tracking Array coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and after fusion-evaporation reaction at the FN tandem accelerator of the University of Cologne, Germany. The Jπ=19/2+ state at 1942 keV in Ba133 is identified as an isomer with a half-life of 66.6(20)ns corresponding to a B(E1) value of 7.7(4)×10-6e2fm2 for the Jπ=19/2+ to Jπ=19/2- transition. The level scheme of Ba134 above the Jπ=10+ isomer is extended to approximately 6 MeV. A pronounced backbending is observed at ω=0.38 MeV along the positive-parity yrast band. The results are compared to the high-spin systematics of the Z=56 isotopes. Large-scale shell-model calculations employing the GCN50:82, SN100PN, SNV, PQM130, Realistic SM, and EPQQM interactions reproduce the experimental findings and elucidate the structure of the high-spin states. The shell-model calculations employing the GCN50:82 and PQM130 interactions reproduce alignment properties and provide detailed insight into the microscopic origin of this phenomenon in transitional Ba134.

The transitional nuclei ¹³⁴Ba and ¹³³Ba are investigated after multinucleon transfer employing the high-resolution Advanced GAmma Tracking Array coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and after fusion-evaporation reaction at the FN tandem accelerator of the University of Cologne, Germany. The Jπ=19/2⁺ state at 1942 keV in ¹³³Ba is identified as an isomer with a half-life of 66.6(20)ns corresponding to a B(E1) value of 7.7(4)×10⁻⁶e²fm² for the Jπ=19/2⁺ to Jπ=19/2⁻ transition. The level scheme of ¹³⁴Ba above the Jπ=10⁺ isomer is extended to approximately 6 MeV. A pronounced backbending is observed at ℏω=0.38 MeV along the positive-parity yrast band. The results are compared to the high-spin systematics of the Z=56 isotopes. Large-scale shell-model calculations employing the GCN50:82, SN100PN, SNV, PQM130, Realistic SM, and EPQQM interactions reproduce the experimental findings and elucidate the structure of the high-spin states. The shell-model calculations employing the GCN50:82 and PQM130 interactions reproduce alignment properties and provide detailed insight into the microscopic origin of this phenomenon in transitional ¹³⁴Ba.

International audience; The transitional nuclei $^{134}$Ba and $^{133}$Ba are investigated after multinucleon transfer employing the high-resolution Advanced GAmma Tracking Array coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and after fusion-evaporation reaction at the FN tandem accelerator of the University of Cologne, Germany. The Jπ=19/2+ state at 1942 keV in $^{133}$Ba is identified as an isomer with a half-life of 66.6(20)ns corresponding to a B(E1) value of 7.7(4)×10−6e2fm2 for the Jπ=19/2+ to Jπ=19/2− transition. The level scheme of $^{134}$Ba above the Jπ=10+ isomer is extended to approximately 6 MeV. A pronounced backbending is observed at ℏω=0.38 MeV along the positive-parity yrast band. The results are compared to the high-spin systematics of the Z=56 isotopes. Large-scale shell-model calculations employing the GCN50:82, SN100PN, SNV, PQM130, Realistic SM, and EPQQM interactions reproduce the experimental findings and elucidate the structure of the high-spin states. The shell-model calculations employing the GCN50:82 and PQM130 interactions reproduce alignment properties and provide detailed insight into the microscopic origin of this phenomenon in transitional $^{134}$Ba.

18 pags., 11 figs., 4 tabs., The transitional nuclei Ba-134 and Ba-133 are investigated after multinucleon transfer employing the high-resolution Advanced GAmma Tracking Array coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and after fusion-evaporation reaction at the FN tandem accelerator of the University of Cologne, Germany. The J(pi) = 19/2(+) state at 1942 keV in Ba-133 is identified as an isomer with a half-life of 66.6(20) ns corresponding to a B(E1) value of 7.7(4) x 10(-6) e(2) fm(2) for the J(pi) = 19/2(+) to J(pi) = 19/2(-) transition. The level scheme of Ba-134 above the J(pi) = 10(+) isomer is extended to approximately 6 MeV. A pronounced backbending is observed at h omega = 0.38 MeV along the positive-parity yrast band. The results are compared to the high-spin systematics of the Z = 56 isotopes. Large-scale shell-model calculations employing the GCN50:82, SN100PN, SNV, PQM130, Realistic SM, and EPQQM interactions reproduce the experimental findings and elucidate the structure of the high-spin states. The shell-model calculations employing the GCN50:82 and PQM130 interactions reproduce alignment properties and provide detailed insight into the microscopic origin of this phenomenon in transitional Ba-134., The research leading to these results has received funding from the German BMBF under Contracts No. 05P15PKFN9 TP1 and No. 05P18PKFN9 TP1, from the European Union Seventh Framework Programme FP7/2007-2013 under Grant No. 262010-ENSAR, from the Spanish Ministerio de Ciencia e Innovación under Contract No. FPA2011-29854-C04, from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2014- 57196-C5, and from the U.K. Science and Technology Facilities Council (STFC). One of the authors (A. Gadea) has been supported by the Generalitat Valenciana, Spain, under Grant No. PROMETEOII/2014/019 and EU under the FEDER program.

International audience; Lifetimes of excited states in At211 were measured using the electronic γ-γ fast timing technique. The nucleus of interest was populated in a Pb208(Li6,3n)At211 fusion-evaporation reaction at the FN Tandem accelerator of the Institute for Nuclear Physics, University of Cologne. The lifetimes of the 17/21− and 23/21− states were determined, together with an upper limit for the 13/21− state. The experimental results are compared to two shell-model calculations, one using a semiempirical interaction for three particles in a single j=9/2 shell and the other using the modified Kuo-Herling interaction in a multi-j model space.

The $5/{2}_{1}^{\ensuremath{-}}$, $9/{2}_{1}^{\ensuremath{-}}$, and $11/{2}_{1}^{\ensuremath{-}}$ states in $^{209}\mathrm{Po}$ were populated in the $\ensuremath{\beta}$ decay of $^{209}\mathrm{At}$ and their lifetimes measured using the electronic $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ fast timing technique. The lifetime of the $9/{2}_{1}^{\ensuremath{-}}$ state is measured for first time. The lifetime of the $5/{2}_{1}^{\ensuremath{-}}$ is measured to be shorter than the value adopted in the literature while the lifetime of the $11/{2}_{1}^{\ensuremath{-}}$ state agrees well with the previous measurement. In order to get deeper insight into the structure of the states, a shell-model calculation was carried out adopting a microscopic effective interaction derived from the realistic CD-Bonn potential. The comparison between theoretical and experimental data for the low-lying negative-parity states of $^{209}\mathrm{Po}$ supports the reliability of the predicted wave functions, which are found to be dominated by the coupling of a neutron hole to the yrast states of $^{210}\mathrm{Po}$. However, it also points to the important role played by minor wave-function components in describing the reduced electromagnetic strengths, suggesting the need of additional configuration mixing for achieving a better quantitative agreement.