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Background: The γ softness of 136Nd makes it possible to study the shape changes induced by two-proton or two-neutron excitation. Purpose: We measure the lifetimes of two-quasiparticle states of the bands based on the 10+ states at 3296 and 3279 keV to investigate the shape change induced by the alignment of two protons or two neutrons in the h11/2 orbital. Methods: The recoil-distance Doppler shift method was used for the study of 136Nd studies, which was formed by the fusion reaction 120Sn(20Ne, 4n)136Nd, at Ebeam = 85 MeV. Calculations were performed within the microscopic-macroscopic approach, based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy. Results: The lifetime of the 10+ state at 3279 keV of 136Nd was measured to be T 10+1/2 = 1.63(9) ns. The lifetimes of the 2+ state at 374 keV and of the 12+ state at 3686 keV of the ground band were also measured to be T 2+1/2 = 26.5(14) ps and T 12+1/2 = 22.5(14) ps. Conclusions: The measured lifetime of 10+ the state at 3279 keV together with other observables confirm the structure change in 136Nd. A rather small reduced hindrance of the electromagnetic decay of the 10+ state at 3279 keV would be consistent with its K-mixed character.

International audience; Background: The γ softness of Nd136 makes it possible to study the shape changes induced by two-proton or two-neutron excitation. Purpose: We measure the lifetimes of two-quasiparticle states of the bands based on the 10+ states at 3296 and 3279 keV to investigate the shape change induced by the alignment of two protons or two neutrons in the h11/2 orbital. Methods: The recoil-distance Doppler shift method was used for the study of Nd136 studies, which was formed by the fusion reaction Sn120(Ne20,4n)Nd136, at Ebeam=85 MeV. Calculations were performed within the microscopic-macroscopic approach, based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy. Results: The lifetime of the 10+ state at 3279 keV of Nd136 was measured to be T1/210+=1.63(9) ns. The lifetimes of the 2+ state at 374 keV and of the 12+ state at 3686 keV of the ground band were also measured to be T1/22+=26.5(14) ps and T1/212+=22.5(14) ps. Conclusions: The measured lifetime of 10+ the state at 3279 keV together with other observables confirm the structure change in Nd136. A rather small reduced hindrance of the electromagnetic decay of the 10+ state at 3279 keV would be consistent with its K-mixed character.

International audience; The g factor of the 56 ns half-life isomeric state in $^{128}$Cs has been measured using the time-differential perturbed angular distribution method. This state is the bandhead of the positive-parity chiral rotational band, which emerges when an unpaired proton, an unpaired neutron hole, and an even-even core are coupled such that their angular momentum vectors are aplanar (chiral configuration). g-factor measurements can give important information on the relative orientation of the three angular momentum vectors. The measured g factor g=+0.59(1) shows that there is an important contribution of the core rotation in the total angular momentum of the isomeric state. Moreover, a quantitative theoretical analysis supports the conclusion that the three angular momentum vectors lie almost in one plane, which suggests that the chiral configuration in $^{128}$Cs demonstrated in previous works by characteristic patterns of electromagnetic transitions appears only above some value of the total nuclear spin.

WOS: 000423131200005, PubMed: 29376727, The g factor of the 56 ns half-life isomeric state in Cs-128 has been measured using the time-differential perturbed angular distribution method. This state is the bandhead of the positive-parity chiral rotational band, which emerges when an unpaired proton, an unpaired neutron hole, and an even-even core are coupled such that their angular momentum vectors are aplanar (chiral configuration). g-factor measurements can give important information on the relative orientation of the three angular momentum vectors. The measured g factor g = +0.59(1) shows that there is an important contribution of the core rotation in the total angular momentum of the isomeric state. Moreover, a quantitative theoretical analysis supports the conclusion that the three angular momentum vectors lie almost in one plane, which suggests that the chiral configuration in Cs-128 demonstrated in previous works by characteristic patterns of electromagnetic transitions appears only above some value of the total nuclear spin., Polish National Science Centre (NCN) [2013/10/M/ST2/00427]; Polish-French Collaboration [COPIN-IN2P3 (06-121)]; Chinese Major State 973 Program [2013CB834400]; National Natural Science Foundation of China [11335002, 11375015, 11461141002, 11621131001]; China Postdoctoral Science Foundation [2015M580007, 2016T90007]; U.S. Department of Energy (DOE), Office of Science, Office of Nuclear Physics [DE-AC02-06CH11357]; U.S. National Science Foundation [1713857], The authors wish to thank the ORSAY Tandem team for providing an excellent and stable beam. This project was supported in part by Polish National Science Centre (NCN) Grant No. 2013/10/M/ST2/00427. This work was partially supported by the Polish-French Collaboration No. COPIN-IN2P3 (06-121). This work was partly supported by the Chinese Major State 973 Program No. 2013CB834400, the National Natural Science Foundation of China (Grants No. 11335002, No. 11375015, No. 11461141002, and No. 11621131001), and the China Postdoctoral Science Foundation under Grants No. 2015M580007 and No. 2016T90007. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (P.W.Z.). This work was partly supported by the U.S. National Science Foundation, Grant No. 1713857.

International audience; The properties of the K-isomer decays in the 134 Nd and 184 Pt nuclei have been investigated. Measurements were carried out in e-γ and γ-γ coincidence modes using electron spectrometers coupled to the central European Array for Gamma Levels Evaluations at the Heavy Ion Laboratory of the University of Warsaw. Internal conversion coefficients were obtained for transitions relevant to the decay of the isomeric states, allowing the determination of multipolarities and mixing ratios as well as hindrance factors. Two possible causes of the weakening of the K forbiddenness, namely rotational K mixing (Coriolis interaction) and triaxiality, are briefly discussed using schematic theoretical models.

The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 2+ 1 state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region. ispartof: Acta Physica Polonica B vol:46 issue:3 pages:607-611 ispartof: location:Zakopane: POLAND status: published

E. Grodner et al. ; 5 pags. ; 4 figs. ; 1 tab. ; PACS numbers: 21.60.Cs, 23.20.Lv, 23.40.−s, Search for a new kind of superfluidity built on collective proton-neutron pairs with aligned spin is performed studying the Gamow-Teller decay of the T=1, Jπ=0+ ground state of Ge62 into excited states of the odd-odd N=Z nucleus Ga62. The experiment is performed at GSI Helmholtzzentrum für Shwerionenforshung with the Ge62 ions selected by the fragment separator and implanted in a stack of Si-strip detectors, surrounded by the RISING Ge array. A half-life of T1/2=82.9(14)ms is measured for the Ge62 ground state. Six excited states of Ga62, populated below 2.5 MeV through Gamow-Teller transitions, are identified. Individual Gamow-Teller transition strengths agree well with theoretical predictions of the interacting shell model and the quasiparticle random phase approximation. The absence of any sizable low-lying Gamow-Teller strength in the reported beta-decay experiment supports the hypothesis of a negligible role of coherent T=0 proton-neutron correlations in Ga62. © 2014 American Physical Society., The present work has been supported by the Generalitat Valenciana, Spain, under Grant No. PROMETEO/2010/ 101 and by MINECO, Spain, under Grants No. AIC-D- 2011-0746, No. FPA2011-29854, No. FIS2011-23565, No. FPA2011-24553, and No. SEV-2012-0249. The experimental activity has been partially supported by the EU under the FP6-Integrated Infrastructure Initiative EURONS, Contract No. RII3-CT-2004-506065, FP7- Integrated Infrastructure Initiative ENSAR, Grant No. 262010, and the Science and Technology Facilities Council (UK), the Swedish Science Council, Istanbul University Scientific Research Projects, No. 21658, and OTKA Contract No. K100835.

Excited states of the Tb146 nucleus have been studied using γ-ray and electron spectroscopy in off-beam and in-beam modes following Sn112(Ar40,3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7−) level in Tb146 shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5−,6−) state. The log ft values have been deduced for 11 β+/EC transitions populating excited states in Gd146. The systematic behavior of spins and parities of the long-lived levels at 0+x keV and the first excited states above them in the N=81 isotones Tb146, Ho148, and Tm150 is discussed

The excited states of Ho148 and Ho149 isotopes are studied using γ-ray and electron spectroscopy in off-beam and in-beam modes following Sn112,114(Ar40,xnyp) reactions. Experiments include measurements of single γ-rays and conversion electron spectra as well as γ-γ, electron-γ, γ−t, and γ−γ−t coincidences with the use of the OSIRIS-II 12-HPGe array and conversion electron spectrometer. Based on the present results, the level schemes of Ho148 and Ho149 are revised and significantly extended, up to about 4 and 5 MeV of excitation energy, respectively. Spin and parity of 5− are assigned to the 9.59-s isomer in Ho148 based on conversion electron results. Previously unobserved γ rays feeding the 10+ isomer in Ho148 and the 27/2− isomer in Ho149 nuclei are proposed. Shell-model calculations are performed. Possible core-excited states in Ho149 are discussed.

Lifetimes of low-lying excited states of the neutron-rich 44, 46Ar nuclei, populated via multinucleon transfer reactions, are measured by means of the differential recoil distance Doppler shift method. The extracted electromagnetic transition probabilities are compared with previous intermediate-energy Coulomb-excitation measurements and with large-scale shell-model calculations. The increase in the deduced B(E2 ; 2+→0+) transition probability from 44Ar to the closed-shell nucleus 46Ar contradicts the earlier results of Coulomb-excitation experiments. Shell-model calculations using different effective interactions agree with the new measured values.

The yrast sequence of the neutron-rich dysprosium isotope Dy-168 has been studied using multinucleon transfer reactions following collisions between a 460-MeV Se-82 beam and an Er-170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2(+) and 4(+) members of the previously measured ground-state rotational band of Dy-168 have been confirmed and the yrast band extended up to 10(+). A tentative candidate for the 4(+) -> 2(+) transition in Dy-170 was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed., This work was partially supported by the European Commission within the Sixth Framework Programme through I3-EURONS contract RII3-CT-2004-506065, the Swedish Research Council, EPSRC/STFC (UK) and U.S. DOE grant No. DE-FG02-91ER40609.

The yrast sequence of the neutron-rich dysprosium isotope 168Dy has been studied using multi-nucleon transfer reactions following collisions between a 460-MeV 82Se beam and a 170Er target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2+ and 4+ members of the previously measured ground state rotational band of 168Dy have been confirmed and the yrast band extended up to 10+. A tentative candidate for the 4+ to 2+ transition in 170Dy was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of Total Routhian Surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed., 15 pages, 7 figures, submitted to Phys. Rev. C

The yrast sequence of the neutron-rich dysprosium isotope Dy-168 has been studied using multinucleon transfer reactions following collisions between a 460-MeV Se-82 beam and an Er-170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2(+) and 4(+) members of the previously measured ground-state rotational band of Dy-168 have been confirmed and the yrast band extended up to 10(+). A tentative candidate for the 4(+) -> 2(+) transition in Dy-170 was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.

Preliminary results from an experiment aiming at Dy-170. Submitted to the LNL Annual Report 2008., 2 pages, 4 figures, Submitted to the LNL Annual Report 2008

The lifetimes of the first excited states of the N=30 isotones Ca-50 and Sc-51 have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f(7/2) shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus Ca-48, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

The lifetimes of the first excited states of the N=30 istones 50Ca and 51Sc have been determined using a novel techinique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA sepctrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This exteneds the lifetime knowledge beyond the f7/2 shell closure and allows to derive the effective proton and neutron charges in the fp shell near the doubly-magic nucleus 48Ca, using large-scale shell-model claculations. These results seem to indicate an orbital dependence of the core polarization along the fp shell.

The lifetimes of the first excited states of the N = 30 isotones 50Ca and 51Sc and the Z = 18 isotopes 44−46Ar isotopes have been determined using a novel technique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA spectrometers in multinucleon transfer reactions. The results allow determinination of the effective charges above 48Ca and test the strength of the N = 28 magic number when moving away from the stability line. Gadea Raga, Andrés, Gadea.Andres@ific.uv.es ; Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es

The lifetimes of the first excited states of the N=30 isotones 50Ca and 51Sc and the Z=18 isotopes 44-46Ar isotopes have been determined using a novel technique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA spectrometers in multinucleon transfer reactions. The results allow determinination of the effective charges above 48Ca and test the strength of the N=28 magic number when moving away from the stability line.

The lifetimes of the first excited states of nuclei around the doubly-magic nucleus 48Ca have been determined using a novel method that combines the Recoil Distance Doppler Shift (RDDS) method with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This novel method and some preliminary results on lifetimes are presented.

Search for a new kind of superfluidity built on collective proton-neutron pairs with aligned spin is performed studying the Gamow-Teller decay of the T=1, J(π)=0+ ground state of (62)Ge into excited states of the odd-odd N=Z nucleus (62)Ga. The experiment is performed at GSI Helmholtzzentrum für Shwerionenforshung with the (62)Ge ions selected by the fragment separator and implanted in a stack of Si-strip detectors, surrounded by the RISING Ge array. A half-life of T1/2=82.9(14) ms is measured for the (62)Ge ground state. Six excited states of (62)Ga, populated below 2.5 MeV through Gamow-Teller transitions, are identified. Individual Gamow-Teller transition strengths agree well with theoretical predictions of the interacting shell model and the quasiparticle random phase approximation. The absence of any sizable low-lying Gamow-Teller strength in the reported beta-decay experiment supports the hypothesis of a negligible role of coherent T=0 proton-neutron correlations in (62)Ga.