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International audience; The Advanced GAmma Tracking Array (AGATA) has been installed at Laboratori Nazionali di Legnaro (LNL), Italy. In this installation, AGATA will consist, at the beginning, of 13 AGATA triple clusters (ATCs) with an angular coverage of 1π, and progressively the number of ATCs will increase up to a 2π angular coverage. This setup will exploit both stable and radioactive ion beams delivered by the Tandem–PIAVE-ALPI accelerator complex and the SPES facility. The new implementation of AGATA at LNL will be used in two different configurations, firstly one coupled to the PRISMA large-acceptance magnetic spectrometer and lately a second one at Zero Degrees, along the beam line. These two configurations will allow us to cover a broad physics program, using different reaction mechanisms, such as Coulomb excitation, fusion-evaporation, transfer and fission at energies close to the Coulomb barrier. These setups have been designed to be coupled with a large variety of complementary detectors such as charged particle detectors, neutron detectors, heavy-ion detectors, high-energy γ-ray arrays, cryogenic and gasjet targets and the plunger device for lifetime measurements. We present in this paper the conceptual design, characteristics and performance figures of this implementation of AGATA at LNL.

International audience; Target properties such as thickness and composition are essential ingredients in nuclear physics experiments, therefore, dedicated analyses to evaluate them before and/or after the measurement are often performed. In some experimental techniques, the exploited detectors allow for the evaluation of these properties on-line, i.e. directly during the experiment. In this paper, we report on the use of analysis methods coming from the Rutherford backscattering spectroscopy technique to obtain on-line information on the target used in a nuclear physics experiment. This measurement was performed at INFN LNL by exploiting the low-energy Coulomb excitation technique. The results have been compared with an independent Rutherford backscattering spectroscopy analysis of the same target performed at INFN LABEC in Florence.

Background: The heaviest T-z = 0 doubly-magic nucleus, Sn-100, and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structur ...

ispartof: PHYSICAL REVIEW C vol:103 issue:4 status: published

The GALILEO array is a high-efficiency γ -ray spectrometer, resident at the Legnaro National Laboratory (LNL)in Italy, and it is currently used in combination with the Si-ball EUCLIDES for the detection of charged-particles. The combined setup was used in the 6 Li+89Y experiment with incident energies of 22 MeV and 34 MeV to investigate the influence of breakup and transfer of weakly bound projectile on the fusion process. Using the coincidence by the charged particles and γ -rays, the different reaction channels can be clearly identified and the different reaction mechanisms can be clearly studied. It is shown that this facility can be used well to explore the fusion reaction mechanisms induced by weakly bound nuclei.

We present recent results on the structure of the one-valence-particle $^{41}$Ca and $^{49}$Ca, and one-valence-hole $^{47}$Ca, nuclei. The isotopes of interest were populated via the cold-neutron capture reactions $^{40}$Ca(n,$\gamma$), $^{48}$Ca(n,$\gamma$) and $^{46}$Ca(n,$\gamma$), respectively. The experiments were performed at the Institut Laue-Langevin, within the EXILL campaign, which employed a large array of HPGe detectors. The $\gamma$ decay and level schemes of these nuclei were investigated by $\gamma$-ray coincidence relationships, leading to the identification of 41, 10, and 6 new transitions in $^{41}$Ca, $^{47}$Ca, and $^{49}$Ca, respectively. Branching ratios and intensities were extracted for the $\gamma$ decay from each state, and $\gamma$-ray angular correlations were performed to establish a number of transition multipolarities and mixing ratios, thus helping in the spin assignment of the states. The experimental findings are discussed along with microscopic, self-consistent beyond-mean-field calculations performed with the Hybrid Configuration Mixing model, based on a Skyrme SkX Hamiltonian. The latter suggests that a fraction of the low-spin states of the $^{41}$Ca, $^{49}$Ca, and $^{47}$Ca nuclei is characterized by the coexistence of either 2p-1h and 1p-2h excitations, or couplings between single-particle/hole degrees of freedom and collective vibrations (phonons) of the doubly-magic "core".

The electromagnetic structure of Zn66 at low excitation energy was investigated via low-energy Coulomb excitation at INFN Legnaro National Laboratories, using the Gamma Array of Legnaro Infn Laboratories for nuclEar spectrOscopy (GALILEO) γ-ray spectrometer coupled to the SPIDER (Silicon PIe DEtectoR). A set of reduced E2, E3, and M1 matrix elements was extracted from the collected data using the gosia code, yielding 12 reduced transition probabilities between the low-spin states and the spectroscopic quadrupole moment of the 21+ state. The B(E2) values for transitions depopulating the 02+ state have been determined for the first time, allowing for the lifetime of this state to be deduced and, consequently, the ρ2(E0;02+→01+) monopole transition strength to be extracted. In addition, the B(E3;31−→01+) value has been determined for the first time in a Coulomb excitation experiment. The obtained results resolve the existing discrepancies between literature lifetimes and demonstrate that Zn66 cannot be described by using simple collective models. Therefore, new state-of-the-art beyond-mean-field and large-scale shell-model calculations were performed in order to interpret the structure of this nucleus. Both the experimental and theoretical results suggest that the triaxial degree of freedom has an important impact on electromagnetic properties of Zn66, while the unique features of the 02+ state indicate its distinct and rather isolated structure.

GALILEO, a new 4 π high-resolution γ -detection array, based on HPGe detectors, has been developed and installed at the Legnaro National Laboratories. The GALILEO array greatly benefits from a fully-digital read-out chain, customized DAQ, and a variety of complementary detectors to improve the resolving power by the detection of particles, ions or high-energy γ -ray transitions. In this work, a full description of the array, including electronics and DAQ, is presented together with its complementary instrumentation.

Gamma-ray angular distributions in oriented $$^{92}$$ Mo produced via the $$^{6}$$ Li+ $$^{89}$$ Y reaction were studied in this work. The characteristic $$\gamma $$ rays in $$^{92}$$ Mo were measured by means of the GALILEO array, which is composed of 25 Compton-suppressed HPGe detectors arranged in a nearly 2 $$\pi $$ geometry. A detailed analysis of the spin-alignment attenuation factors ( $$\alpha _2$$ ) for different excited states in $$^{92}$$ Mo was performed, by analyzing the measured angular distribution coefficients of several pure-E2 transitions. The relationship between $$\alpha _2$$ and the spin was established in $$^{92}$$ Mo and the 244-keV transition between the 5 $$^-_1$$ and 4 $$^+_1$$ states resulted to have a E1 + M2 character with a mixing ratio ( $$\delta $$ ) of $$-0.05^{+0.05}_{-0.06}$$ , consistent with shell model calculations.

The lifetime of the 2(+) and 9(-), 11(-), 13(-), 15(-) states in the neutron-deficient Te-110 was measured for the first time using the recoil distance Doppler shift technique. The reported value of the reduced transition probability B(E2; 0(g.s)(+) -> 2(+)) = 4.3(8) x 10(3) e(2) f m(4) supports the systematic for even-mass Te isotopes and was interpreted g.s in the framework of the large-scale shell model and cranked shell model calculations. The measured reduced transition probabilities in the negative-parity yrast band revealed the upward trend towards the high spins. The enhanced collectivity is discussed in terms of the tilted axis cranking approach and the symmetry configuration mixing method with the Gogny D1S interaction., DoE [DE-FG02-95ER4093]; Spanish MICINN [PGC2018-094583-B-I00], The authors would like to thank the technical staff of the LNL Legnaro facility for their assistance in providing excellent operation of the XTU-tandem accelerator. The authors wish to acknowledge the support of local engineers P. Cocconi and R. Isocrate. The work was partially supported by the DoE Grant No. DE-FG02-95ER4093 and Spanish MICINN Grant No. PGC2018-094583-B-I00.

Physics letters / B 816, 136183 (2021). doi:10.1016/j.physletb.2021.136183, Published by North-Holland Publ., Amsterdam

Three nearly degenerate pairs of doublet bands are identified in $^{131}$Ba. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners π(d5/2,g7/2) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in $^{131}$Ba have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in $^{131}$Ba are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry.

Decay of the $49/{2}^{+}$, $0.51\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{s}$ isomeric state in $^{147}\mathrm{Gd}$ was reinvestigated in the $\ensuremath{\gamma}$-coincidence catcher experiment using the $^{76}\mathrm{Ge}(^{76}\mathrm{Ge},5n$) reaction and the GASP $\ensuremath{\gamma}$ detector array. A previously suggested extraordinary complexity of the decay was confirmed and established down to intensity level better than ${10}^{\ensuremath{-}3}$/decay, involving 400 transitions and 89 levels populated between the isomer and the $^{147}\mathrm{Gd}$ ground state. The earlier measured electron conversion coefficients (ECC) and $\ensuremath{\gamma}$ angular distributions, together with the total ECC extracted presently for low-energy transitions from the intensity balance, allowed to assign spin and parity values to all of the observed levels. Discussion of the level structure is restricted to few important cases clarified by the present investigation in the low-energy part of the decay scheme. Those involved the identification of the new $M2$ and $E2$ branches populating two new levels in the decay of the ${27/2}^{\ensuremath{-}}$ isomer and firm location of positive parity levels arising in the coupling of this isomer with the ${3}^{\ensuremath{-}}$ core excitation. In the upper part it was concluded that the observed complexity of the decay is initiated by fast low-energy $M1$ transitions populating a group of similar structure levels located within 7.8--8.0 MeV excitation energy range. Some statistical features of the observed complex isomeric decay are reviewed and discussed.

International audience; SPIDER is a new array of segmented silicon detectors for low-energy Coulomb-excitation experiments, designed as an ancillary device for modern γ -ray spectrometers such as GALILEO and AGATA. Currently, it is used at the INFN Legnaro National Laboratories (LNL) for experiments with the GALILEO γ -ray array and the stable beams provided by the Tandem-XTU, ALPI-PIAVE accelerator complex. In this paper, a detailed description of SPIDER is presented, as well as the outcomes from the first in-beam experiment of the array coupled with GALILEO. In particular, radiation damage and cross-talk/charge-sharing effects induced by energetic heavy ions in SPIDER are investigated and the capabilities of the array to perform on-line Rutherford back-scattering analysis of the exploited target are presented. The material reported here can be used to plan future experiments with the GALILEO-SPIDER setup with the presently available stable beams at LNL and paves the way for future experimental campaigns with the radioactive beams provided in the near future by the SPES facility at LNL.

Background: Shape coexistence in the Z≈82 region has been established in mercury, lead, and polonium isotopes. For even-even mercury isotopes with 100≤N≤106 multiple fingerprints of this phenomenon are observed, which seems to be no longer present for N≥110. According to a number of theoretical calculations, shape coexistence is predicted in the Hg188 isotope. Purpose: The aim of this work was to measure lifetimes of excited states in Hg188 to infer their collective properties, such as the deformation. Extending the investigation to higher-spin states, which are expected to be less affected by band-mixing effects, can provide additional information on the coexisting structures. Methods: The Hg188 nucleus was populated using two different fusion-evaporation reactions with two targets, Gd158 and Gd160, and a beam of S34 provided by the Tandem-ALPI accelerator complex at the Laboratori Nazionali di Legnaro. The channels of interest were selected using the information from the Neutron Wall array, while the γ rays were detected using the GALILEO γ-ray spectrometer. Lifetimes of excited states were determined using the recoil-distance Doppler-shift method, employing the dedicated GALILEO plunger device. Results: Lifetimes of the states up to spin 16ℏ were measured and the corresponding reduced transition probabilities were calculated. Assuming two-band mixing and adopting, as done commonly, the rotational model, the mixing strengths and the deformation parameters of the unperturbed structures were obtained from the experimental results. In order to shed light on the nature of the observed configurations in the Hg188 nucleus, the extracted transition strengths were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach, limited to axial shapes, and the five-dimensional collective Hamiltonian, including the triaxial degree of freedom. Conclusions: The first lifetime measurement for states with spin ≥6 suggested the presence of an almost spherical structure above the 121+ isomer and allowed elucidating the structure of the intruder band. The comparison of the extracted B(E2) strengths with the two-band mixing model allowed the determination of the ground-state band deformation. Both beyond-mean-field calculations predict coexistence of a weakly deformed band with a strongly prolate-deformed one, characterized by elongation parameters similar to those obtained experimentally, but the calculated relative position of the bands and their mixing strongly differ.

Low-energy Coulomb excitation is one of the simplest and most known tools to study the nuclear shape; for this reason it is nowadays widely used at radioactive beam facilities. The SPES facility, for the acceleration of radioactive beams will soon provide the first exotic beams at the Laboratori Nazionali di Legnaro (LNL) in Italy.a#13; To this end a new particle detector (Silicon PIe DEtectoR) to be used for Coulomb excitation studies has been installed at LNL. SPIDER has been coupled to the GALILEO array of germanium detectors, and a number of experiments have been already successfully performed. This paves the way for future experiments with the radioactive beams provided by the SPES facility.

The g factor of the $$12^+$$ K-isomer in $$^{174}$$ W has been measured by means of the time-differential perturbed angular distribution technique as $$g(12^+)=+0.304(11)$$ . In addition, the half-life of the isomer has been remeasured as $$T_{1/2}(12^+)=124(8)$$ ns, in agreement with the literature value and confirming the anomalous hindrance F of the E2 transition to the $$10^+$$ level of the ground state band with respect to the $$\gamma $$ -tunnelling model prediction. The measured g factor has been compared with estimates based on experimental g factors from odd-mass isotopes in the same mass region and with Nilsson model calculations. The results establish unique features of the $$12^+$$ K-isomer in $$^{174}$$ W, which can possess a non-pure intrinsic configuration and/or can be characterised by values of the intrinsic quadrupole moment $$Q_0$$ and the rotational g factor $$g_R$$ significantly different with respect to the majority of K-isomers at mass $$A \approx 180$$ .

Aydın, Sezgin ( Aksaray, Yazar ), Level structures of Rn212 have been studied by in-beam γ-ray spectroscopic methods using the Bi209(Li6,3n)Rn212 reaction at beam energies of 28, 30, and 34 MeV. A number of new nonyrast states based on πh9/24 and πh9/23f7/2 configurations have been identified. A 3(-) collective state is also proposed at 2121 keV, which is most likely formed by mixing the octupole vibration with the 3- member of the πh9/23i13/2 multiplet. The level scheme is compared with large-scale shell model calculations and discussed in terms of excitations of valence protons and without contributions from the Pb208 core. An overall excellent agreement is obtained for states that can be described in this model space.

6 pags., 4 figs., The γ-ray emission from the nuclei Fe following Coulomb excitation at bombarding energy of 400-440 AMeV was measured with special focus on E1 transitions in the energy region 4-8 MeV. The unstable neutron-rich nuclei Fe were produced at the FAIR-GSI laboratories and selected with the FRS spectrometer. The γ decay was detected with AGATA. From the measured γ-ray spectra the summed E1 strength is extracted and compared to microscopic quasi-particle phonon model calculations. The trend of the E1 strength with increasing neutron number is found to be fairly well reproduced with calculations that assume a rather complex structure of the 1 states (three-phonon states) inducing a strong fragmentation of the E1 nuclear response below the neutron binding energy., This work was partially supported by INFN (Italy) and STFC (UK), the Swedish Research Council (Vetenskapsrådet, VR 2010-147, 2011-5253, and 2016-3969), BMBF NuSTAR-AGATA 05P18RDFN9 and BMBF NuSTAR 05P18RDFN1. The project was co-funded by the European Commission under the 7th Framework Program for RTD (2007-2013) under the Capacities Program (Contract Number 262010, ENSAR). This work was par-tially supported by the Ministry of Science, and Generalitat Valenciana, Spain, under the Grants SEV-2014-0398, FPA2017-84756-C4, PROMETEO/2019/005 and by the EU FEDER funds.

The lifetimes of the low-lying excited states 2(+) and 4(+) have been directly measured in the neutron-deficient Sn-106,Sn-108 isotopes. the nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. the emitted gamma rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2; 2(1)(+) -> 0(g.s)(+)) values and it describes well the experimental pattern for Sn104-114 ; the B(E2;(+)(4) -> 2(1)(+)) values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in Sn-108. (C) 2020 the Authors. Published by Elsevier B.V., European Union's Seventh Framework Programme for Research and Technological DevelopmentEuropean Union (EU) [262010]; Fondazione Cassa di Risparmio Padova e Rovigo under the project CONPHYT, starting grant in 2017; Swedish Research CouncilSwedish Research Council [822-2005-3332, 821-2010-6024, 821-2013-2304, 621-20145558, 2017-0065]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [2005.0184]; Scientific and Technological Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114F473]; Ministerio de Ciencia e InnovacionInstituto de Salud Carlos IIISpanish Government [SEV-2014-0398, FPA2017-84756-C4, EEBBI-15-09671]; Generalitat ValencianaGeneralitat Valenciana [PROMETEO/2019/005]; EU-FEDER fundsEuropean Union (EU); Croatian Science Foundation [7194]; Hungarian National Research and Innovation Office (NKFIH) [K128947, PD124717, GINOP-2.3.3-15-2016-00034]; Polish National Science Centre under the COPIN-IN2P3 project [2014-14-M-ST2-00738, 2016-22M-ST2-00269, 2017-25-B-ST2-01569]; Polish National Science Centre under the COPIGAL project [2014-14-M-ST2-00738, 2016-22M-ST2-00269, 2017-25-B-ST2-01569]; Polish National Science Centre under the POLITA project [2014-14-M-ST2-00738, 2016-22M-ST2-00269, 2017-25-B-ST2-01569], The authors would like to thank the AGATA and VAMOS collaborations. Special thanks go to the GANIL technical staff for their help in setting up the apparatuses and the good quality beam and to A. Poves for his fruitful comments. This work was partially supported by the European Union's Seventh Framework Programme for Research and Technological Development (grant no. 262010). A.G. acknowledges the support of the Fondazione Cassa di Risparmio Padova e Rovigo under the project CONPHYT, starting grant in 2017. the work was also supported (B.C, H.L., J.N. and U.J.) by Swedish Research Council under the grant agreements nos. 822-2005-3332, 821-2010-6024, 821-2013-2304, 621-20145558 and 2017-0065, and by the Knut and Alice Wallenberg Foundation grant no. 2005.0184, (B.S.) by the Scientific and Technological Council of Turkey (TUBITAK) under the project no. 114F473, (A.G., A.J. and R.P.) by the Ministerio de Ciencia e Innovacion under the contracts nos. SEV-2014-0398, FPA2017-84756-C4 and EEBBI-15-09671, by the Generalitat Valenciana under the grant agreement no. PROMETEO/2019/005 and by the EU-FEDER funds, (T.M and S.S.) by the Croatian Science Foundation under the project no. 7194, (I.K and D.S.) by the Hungarian National Research and Innovation Office (NKFIH) under the project nos. K128947, PD124717 and GINOP-2.3.3-15-2016-00034, (M.P.) by the Polish National Science Centre with the grants nos. 2014-14-M-ST2-00738, 2016-22M-ST2-00269 and 2017-25-B-ST2-01569 under the COPIN-IN2P3, COPIGAL and POLITA projects.

The GALILEO ?-ray spectrometer, installed at the Laboratori Nazionali di Legnaro (LNL), benefits from intense stable beams provided by the Tandem-ALPI-PIAVE accelerator complex and from radioactive beams to be delivered in the near future by the SPES facility. The spectrometer is complemented with a variety of ancillary devices to allow for nuclear structure and reaction studies. The 4? Si-ball array EUCLIDES coupled to the GALILEO ?-ray spectrometer represents one of the commonly used setup for experiments aiming at spectroscopic studies. High-efficiency detection of light-charged particles in a fusion–evaporation reaction guarantees good discrimination of different reaction channels and provides essential information for the kinematic reconstruction. In this paper we discuss a configuration of the EUCLIDES array developed for the lifetime measurements of nuclear excited states populated in a fusion–evaporation reaction. In such a configuration a part of the EUCLIDES detectors is disassembled allowing for the installation of a plunger device in the reaction chamber. The reduced configuration of EUCLIDES provides high detection efficiency necessary for reliable light charged-particle discrimination. We report on the commissioning experiment focused on the 58Ni(58Ni,3p)113I reaction. The lifetimes of 11/2? and 15/2? states were measured by applying the Recoil Distance Doppler Shift method to be equal to 206(20) ps and 7.9(12) ps correspondingly and were in good agreement with the values cited in the literature. Thus, the combination of the GALILEO and EUCLIDES arrays, and the plunger device has resulted in a powerful experimental setup to determine lifetimes of excited states in neutron-deficient nuclei in the picosecond range. © 2020 Elsevier B.V., Fondazione Cassa di Risparmio di Padova e Rovigo Narodowe Centrum Nauki, NCN: 2017/25/B/ST2/01569 Narodowym Centrum Nauki, NCN, The authors would like to thank the technical staff of the LNL-INFN facility for their assistance in providing excellent operation of the XTU-Tandem accelerator. The authors wish to acknowledge the support of local engineers P. Cocconi and R. Isocrate. The work of G. Jaworski was supported by the National Science Centre, Poland (NCN) (grant no. 2017/25/B/ST2/01569 ). A. Goasduff acknowledges the support of the CARIPARO foundation under the Starting Grant 2017 .

Export Date: 14 August 2020 ispartof: Acta Physica Polonica B vol:51 issue:3 pages:683-688 ispartof: location:POLAND, Piaski status: published

Lifetimes of excited states of the phosphorus isotopes 1533,34,35,36P have been measured by using the differential recoil-distance method. The isotopes of phosphorus were populated in binary grazing reactions initiated by a beam of S36 ions of energy 225 MeV incident on a thin Pb208 target mounted in the Cologne plunger apparatus. The combination of the PRISMA magnetic spectrometer and an early implementation of the AGATA γ-ray tracking array was used to detect γ rays in coincidence with projectile-like nuclear species. Lifetime measurements of populated states were made within the range from about 1 to 100 ps. The number of states for which lifetime measurements were possible was limited by statistics. For P33, lifetime limits were determined for the first 3/2+ and 5/2+ states at 1431 and 1848 keV, respectively; the results are compared with previous published lifetime values. The lifetime of the first 2+ state of P34 at 429 keV was determined and compared with earlier measurements. For P35, the states for which lifetimes, or lifetime limits, were determined were those at 2386, 3860, 4101, and 4493 keV, with Jπ values of 3/2+, 5/2+, 7/21−, and 7/22−, respectively. There have been no previous published lifetimes for states in this nucleus. A lifetime was measured for the stretched π(1f7/2)⊗ν(1f7/2)Jπ=(7+) state of P36 at 5212 keV and a lifetime limit was established for the stretched π(1d3/2)⊗ν(1f7/2)Jπ=(5−) state at 2030 keV. There are no previously published lifetimes for states of P36. Measured lifetime values were compared with the results of state-of-the-art shell-model calculations based on the PSDPF effective interaction. In addition, measured branching ratios, published mixing ratios, and electromagnetic transition rates, where available, have been compared with shell-model values. In general, there is good agreement between experiment and the shell model; however there is evidence that the shell-model values of the M1 transition rates for the 3/21+→1/2+ (ground state) and 5/21+→3/21+ transitions in P33 underestimate the experimental values by a factor between 5 and 10. In P35 there are some disagreements between experimental and shell-model values of branching ratios for the first and second excited 7/2− states. In particular, there is a serious disagreement for the decay characteristics of the second 7/2− state at 4493 keV, for which the shell-model counterpart lies at 4754 keV. In this case, the shell-model competing electromagnetic decay branches are dominated by E1 and M1 transitions.

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.

The neutron-rich isotopes 211;213Tl, beyond the N = 126 shell-closure, have been studied for the first time in isomer γ-ray decay, exploiting the fragmentation of a primary uranium beam at the FRS-RISING (FRagment Separator-Rare ISotopes INvestigation at GSI) setup at GSI. The observed isomeric states in 211;213Tl show a deviation from the seniority-like scheme of 209Tl. The possible interpretation of the data is discussed on the basis of energy-level systematics and shell-model calculations.

In recent years, a number of both theoretical and experimental investigations have been performed focusing on the zirconium isotopic chain. In particular, state-of-the-art Monte Carlo shell-model calculations predict shape coexistence in these isotopes. In this context, the 94Zr nucleus, which is believed to possess a nearly spherical ground state, is particularly interesting since the purported deformed structure is basedon the low-lying 02+ state, making it amenable for detailed study. In order to provide definitive conclusionson the shapes of the low-lying states, two complementary experiments to study 94Zr by means of low-energy Coulomb excitation were performed. This data will allow the quadrupole moments of the 21,2+ levels to be extracted as well as for the deformation parameters of the 01,2+ states to be determined and, thus, definitive conclusions to be drawn on the role of shape coexistence in this nucleus for the first time. The first experiment was performed at the INFN Legnaro National Laboratory with the GALILEO-SPIDER setup, which, for the first time, was coupled with 6 lanthanum bromide scintillators (LaBr3:Ce) in order to maximize the γ-ray detection effciency. The second experiment was performed at the Maier-Leibnitz Laboratory (MLL) in Munich and used a Q3D magnetic spectrograph to detect the scattered 12C ions following Coulomb excitation of 94Zr targets.

This short paper presents the investigation of reaction mechanism induced by 6Li through a particle­γ coincidence measurement. The data have been taken from a 6Li+89Y experimentwhich is performed inINFN-LNL, Italy. In this experiment, the light charged particles are detected by a Si­ball, named EUCLIDES, and the γ rays are collected by a HPGe detector array, called GALILEO. In this contribution, scientific motivations, experimental details and some results, such as α­γ analysis, are presented.

In a fusion-evaporation reaction, nuclei are produced by evaporating light-charged particles and neutrons from the compound nucleus. Typically, a nucleus of interest is produced as a result of a part of the total cross-section and, in order to guarantee a good channel discrimination, a particle detector, like the EUCLIDES $4\pi$ Si-ball array, is necessary. EUCLIDES has been quoted in more than a hundred publications resulting from many experiments performed in combination with the EUROBALL and GASP $\gamma$-ray spectrometers. The present paper reports on the upgraded version of EUCLIDES, that is presently coupled to the new GALILEO $\gamma$-ray spectrometer, installed at the Laboratori Nazionali di Legnaro, INFN. The design, characteristics and performance of the EUCLIDES array are presented and discussed.

The band built on the Kπ = 8−, T1/2 = 9.4 ms isomer of 130Ba has been identified, filling the gap in the systematics of the dipole bands built on the 8− isomers in the N = 74 isotones from 128Xe to 138Gd. The use of the GALILEO array in conjunction with its ancillaries EUCLIDES and Neutron Wall, helped to firmly place the newly identified transitions on top of the long-lived isomer. The extracted gK and gR gyromagnetic factors are in agreement with the 7/2+[404] ⊗ 9/2−[514] two-neutron Nilsson configuration. Particle-rotor model calculations give an understanding of the limited degree of K mixing. The experimental information on the Kπ = 8− isomer of 130Ba is now the most complete among the K isomers of the N = 74 isotones.

The high-spin structures of 136Ba and 137Ba are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. 136Ba is populated in a 136Xe+238U MNT reaction employing the high-resolution Advanced GAmma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and in two 9Be + 130Te fusion-evaporation reactions using the High-efficiency Observatory for -Ray Unique Spectroscopy (HORUS) at the FN tandem accelerator of the University of Cologne, Germany. Furthermore, both isotopes are populated in an elusive reaction channel in the 11B+130Te fusion-evaporation reaction utilizing the HORUS -ray array. The level scheme above the J� = 10+ isomer in 136Ba is revised and extended up to an excitation energy of approx. 5.5 MeV. From the results of angular-correlation measurements, the Ex = 3707- and Ex = 4920-keV states are identified as the bandheads of positive- and negative-parity cascades. While the high-spin regimes of both 132Te and 134Xe are characterized by high-energy 12+ ! 10+ transitions, the 136Ba E2 ground-state band is interrupted by negativeparity states only a few hundred keV above the J� = 10+ isomer. Furthermore, spins are established for several hitherto unassigned high-spin states in 137Ba. The new results close a gap along the highspin structure of N < 82 Ba isotopes. Experimental results are compared to large-scale shell-model calculations employing the GCN50:82, Realistic SM, PQM130 and SN100PN interactions. The calculations suggest that the bandheads of the positive-parity bands in both isotopes are predominantly of proton character.

Excited states of odd-odd nucleus 92Nb and odd-A nucleus 93Nb were populated in the 6Li+ 89Y reaction with an incident energy of 34 MeV. The processes that produce 92,93Nb and can be measured by a combination of light charged particle and gamma ray measurements are discussed. Twenty new transitions are observed and eight new levels are constructed in 92Nb, and in addition two new transitions are added to the level scheme of 93Nb. Using shell model calculations, the low-lying structure of 92Nb is investigated and compared with the experimental results.

International audience; Excited states of the rubidium isotopes$_{37}^{87, 89, 91}$Rb have been studied at the INFN Legnaro National Laboratory. Measurements of the $\gamma$ -ray decay of fragments produced in binary grazing reactions resulting from the interaction of a beam of 530 MeV$^{96}$Zr ions with a$^{124}$Sn target have been complemented by studies of the $\gamma$ -ray decay of fission fragments produced in the interaction of a beam of 230 MeV$^{36}$S ions with a thick$^{176}$Yb target. The structure of the yrast states of$_{37}^{87, 89, 91}$Rb has been discussed within the context of spherical shell-model and cranked Nilsson-Strutinsky calculations.