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Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned \nu h11/2^2 , 7/2+[523] \otimes 9/2-[514] Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A=130 mass region. The t-band is fed by a dipole band involving two additional h11/2 protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a gamma-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A = 130 mass region., Comment: 8 pages, 7 figures

A new device, the GALILEO plunger, has been developed for lifetime measurement studies using the GALILEO γ -ray detector array at the Laboratori Nazionali di Legnaro (LNL) in Legnaro, Italy. This plunger device holds two stretched metal foils in the beam path for the use of the recoil distance Doppler-shift technique in order to measure lifetimes of nuclear excited states in the range of 1 ps to 1 ns. The compact design allows one to combine different auxiliary detectors with the plunger device inside the target chamber and takes care of high γ -ray transparency. The design and control of the device are presented in this paper, together with lifetimes of excited states in 180Pt measured within the first in-beam commissioning run.

Detailed information on isomeric states in A ≈ 135 nuclei is exploited to benchmark shell-model calculations in the region northwest of doubly-magic nucleus 132Sn. The N = 79 isotones 133Xe and 135Ba are studied after multinucleon transfer (MNT) in the 136Xe + 208Pb 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 a pulsed-beam experiment at the FN tandem accelerator of the University of Cologne, Germany utilizing a 9Be+130Te fusion-evaporation reaction at a beam energy of 40 MeV. Isomeric states are identified via delayed γ-ray spectroscopy. Hitherto tentative excitation energy, spin, and parity assignments of the 2107-keV Jπ = 23/2+ isomer in 133Xe are confirmed and a half-life of T1/2 = 8.64(13) ms is measured. The 2388-keV state in 135Ba is identified as a Jπ = 23/2+ isomer with a half-life of 1.06(4) ms. The new results show a smooth onset of isomeric Jπ = 23/2+ states along the N = 79 isotones and close a gap in the high-spin systematics towards the recently investigated Jπ = 23/2+ isomer in 139Nd. The resulting systematics of M2 reduced transition probabilities is discussed within the framework of the nuclear shell model. Latest large-scale shell-model calculations employing the SN100PN, GCN50:82, SN100-KTH, and a realistic effective interaction reproduce the experimental findings generally well and give insight into the structure of the isomers.

The gamma-ray decay of excited states of the one-valence-proton nucleus Sb-133 has been studied using cold-neutron induced fission of U-235 and Pu-241 targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between gamma-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 mu s isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus Sn-132 and the valence proton, using Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.

In this work we present the architecture and results of a fully digital Front End Electronics (FEE) read out system developed for the GALILEO array. The FEE system, developed in collaboration with the Advanced Gamma Tracking Array (AGATA) collaboration, is composed of three main blocks: preamplifiers, digitizers and preprocessing electronics. The slow control system contains a custom Linux driver, a dynamic library and a server implementing network services. The digital processing of the data from the GALILEO germanium detectors has demonstrated the capability to achieve an energy resolution of 1.53 per mil at an energy of 1.33 MeV., Comment: 5 pages, 6 figures, preprint version of IEEE Transactions on Nuclear Science paper submitted for the 19th IEEE Real Time Conference

The magnetic moment of the 19/2- state in 39K has been measured by the transient field technique. The state was excited by the inverse reaction 12C(32S,pa)39K and the recoil nucleus traversed a thin Gd foil. Its absolute g-factor, g= 0.35(3), was obtained by an internal calibration, which makes use of the magnetic moment of the 15/2+ state in 41Ca also excited in the same reaction. The experimental result agrees well within shell model predictions.

The electromagnetic decay properties of high spin states in 52Mn have been studied through various experiments with the GASP and EUROBALL arrays plus the ISIS charged-particle detector, the Neutron-Wall and the Recoil Filter Detector. From 7-7-particles coincidence measurements, spins and parities of these states have been determined and using the Doppler-shift attenuation method the mean life of some of these states have been determined. These results are compared with large scale shell-model calculations in the full fp shell.

The transitional nucleus 131Xe is investigated after multinucleon transfer (MNT) in the 136Xe+208Pb and 136Xe+238U reactions employing the high-resolution Advanced GAmma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy and as an elusive reaction product in the fusion-evaporation reaction 124Sn(11B,p3n) 131Xe employing the HORUS γ-ray array coupled to a double-sided silicon strip detector (DSSSD) at the University of Cologne, Germany. The level scheme of 131Xe is extended to 5 MeV. A pronounced backbending is observed at ~ω ≈ 0.4 MeV along the negative-parity one-quasiparticle νh11/2(α = −1/2) band. The results are compared to the high-spin systematics of the Z = 54 isotopes and the N = 77 isotones. Large-scale shell-model calculations (LSSM) employing the PQM130, SN100PN, GCN50:82, SN100-KTH and a realistic effective interaction reproduce the experimental findings and provide guidance to elucidate the structure of the high-spin states. Further calculations in 129−132Xe provide insight into the changing nuclear structure along the Xe chain towards the N = 82 shell closure. Proton occupancy in the π 0h11/2 orbital is found to be decisive for the description of the observed backbending phenomenon.

Transition probabilities of intermediate-spin yrast and non-yrast excitations in 80, 82Se were investigated in a recoil distance Doppler-shift (RDDS) experiment performed at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. The Cologne Plunger device for deep inelastic scattering was used for the RDDS technique and was combined with the AGATA Demonstrator array for the γ-ray detection and coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 80Se, the level lifetimes of the yrast (6+1) and (8+1) states and of a non-yrast band feeding the yrast 4+1 state are determined. A spin and parity assignment of the head of this sideband is discussed based on the experimental results and supported by large-scale shell-model calculations. In 82Se, the level lifetimes of the yrast 6+1 state and the yrare 4+2 state and lifetime limits of the yrast (10+1) state and of the 5−1 state are determined. Although the experimental results contain large uncertainties, they are interpreted with care in terms of large-scale shell-model calculations using the effective interactions JUN45 and jj44b. The excited states' wave functions are investigated and discussed with respect to the role of the neutron g9/2 orbital.

A Coulomb-excitation experiment to study electromagnetic properties of Ca42 was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in Ca42 were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2 matrix elements coupling six low-lying states in Ca42, including the diagonal E2 matrix elements of 21+ and 22+ states, were determined using the least-squares code gosia. The obtained set of reduced E2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 01,2+ and 21,2+ states, as well as triaxiality for 01,2+ states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in Ca42.

The measurement of one-neutron stripping cross sections for the $^{89}\mathrm{Y}(^{6}\mathrm{Li},^{5}\mathrm{Li})^{90}\mathrm{Y}^{*}$ reaction at 22 MeV and 34 MeV is reported, using both in-beam and off-beam $\ensuremath{\gamma}$-ray spectroscopy methods. Characteristic $\ensuremath{\gamma}$ lines of $^{90}\mathrm{Y}$ are clearly identified by both the $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and proton-$\ensuremath{\gamma}$ coincidence methods. The obtained cross section of one-neutron stripping at 34 MeV is found to be much smaller than that at 22 MeV. The one-neutron stripping cross sections measured for this system have the same order of magnitude as the one measured for the same reaction for the $^{6}\mathrm{Li}+^{96}\mathrm{Zr}$ system at energies around the Coulomb barrier. Parameter-free coupled reaction channel calculations agree quite well with the experimental data. Theoretical study of the effect of the one-neutron transfer on the elastic total fusion cross section is performed.

Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. In comparison with radioactive ion beam (RIB), the beam intensities of stable weakly bound nuclei such as 6,7Li and 9Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements induced by these nuclei have already been performed. However, the conclusion of reaction dynamics was not clear and has contradiction. In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV was performed on Galileo array in combination with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using the coincidence by the charged particles and γ-rays, the different reaction channels can be clearly identified.

An in-beam test of two pixel-type silicon detectors of the TRACE detector project has been performed at Laboratori Nazionali di Legnaro (Italy). The aim was to investigate the lowest kinetic energy values at which isotopic identification of heavy-ion reactions products with mass $ A\sim 10$ is possible, by using a single-layer silicon detector. Two separate read-out chains, analog and digital, were used, and the Pulse Shape Analysis technique was employed to obtain the particle identification matrices for the digitally processed data. The results confirmed the high capability of the Pulse Shape Analysis method which can be used for light ion identification, with performances similar to the analog approach. Separation in both charge and mass was obtained for Li and Be isotopes, however, the presence of a significant background from alpha particles severely limited the data analysis in the lower energy region. Due to this effect, the identification of the light products (7, 6Li isotopes) could be possible down to $ \sim 24.5$ MeV only, while the 9, 7Be isotopes were separable down to $ \sim 29$ MeV. This gives the value of $ < 4$ MeV/nucleon as the lowest kinetic energy for light products identification by using the pixel-type detectors of the TRACE project, in the present experimental conditions.

International audience; Isomeric states in isotopes in the vicinity of doubly-magic 208Pb were populatedfollowing reactions of a relativistic 208Pb primary beam impinging on a9Be fragmentation target. Secondary beams of 198,200,202,206Pb and 206Hg wereisotopically separated and implanted in a passive stopper positioned in thefocal plane of the GSI Fragment Separator. Delayed γ rays were detected withthe Advanced Gamma Tracking Array (AGATA). Decay schemes were reevaluatedand interpreted with shell-model calculations. The momentumdependentpopulation of isomeric states in the two-nucleon hole nuclei206Pb/206Hg was found to differ from the population of multi neutron-holeisomeric states in 198,200,202Pb.

$^{111}\mathrm{Ag}$ and $^{113}\mathrm{Ag}$ were produced in induced fission reaction, where yrast and near-yrast states were populated. To interpret the new data the Interacting Boson-Fermion Model was used. A good agreement with the experimental data is achieved, suggesting that the two Ag nuclei have a well-developed collectivity, superimposed on $\ensuremath{\pi}{g}_{9/2}^{\ensuremath{-}3}$ excitations previously observed throughout the entire isotopic chain.

Background: While the $N=50$ shell-gap evolution towards $^{78}\mathrm{Ni}$ is presently in the focus of nuclear structure research, experimental information on the neutron effective single-particle energy sequence above the $^{78}\mathrm{Ni}$ core remain scarce. Direct nucleon-exchange reactions are indeed difficult with presently available post-accelerated radioactive-ion beams (especially for high orbital-momentum orbitals) in this exotic region.Purpose: In this study we probe the evolution of the $\ensuremath{\nu}1{g}_{7/2}$ effective single-particle energy which is a key to understanding the possible evolution of the spin-orbit splitting due to the proton-neutron interaction in the $^{78}\mathrm{Ni}$ region. To achieve this goal, a method based on lifetime measurements is used for the first time. The obtained lifetimes of the $7/{2}_{1}^{+}$ states in $^{87}\mathrm{Kr}$ and $^{85}\mathrm{Se}$ are used to investigate the $\ensuremath{\nu}1{g}_{7/2}$ evolution.Method: Yrast and near-yrast states in the light $N=51$ isotones $^{85}\mathrm{Se}$ and $^{87}\mathrm{Kr}$ were populated via multinucleon transfer reactions, using a $^{82}\mathrm{Se}$ beam and a $^{238}\mathrm{U}$ target at the LNL tandem-ALPI facility. The prompt $\ensuremath{\gamma}$ rays were detected by the AGATA Demonstrator and particle identification was performed using the PRISMA spectrometer. Lifetime measurements were performed by using the Cologne plunger device for deep inelastic reactions and the Recoil Distance Doppler Shift technique.Results: We obtain ${\ensuremath{\tau}}_{(7/{2}_{1}^{+})}=0.{4}_{\ensuremath{-}0.4}^{+1.6}$ ps for $^{87}\mathrm{Kr}$. In the case of $^{85}\mathrm{Se}$ an upper limit of 3(2) ps is obtained for the ${\ensuremath{\tau}}_{7/{2}_{1}^{+}}$ value.Conclusion: For $^{87}\mathrm{Kr}$, the measured $(7/{2}_{1}^{+})$ lifetime is consistent with a core-coupled ${2}^{+}\ensuremath{\bigotimes}\ensuremath{\nu}2{d}_{5/2}$ configuration for this state. This result is consistent with that obtained by direct reaction, which validates our method. For $^{85}\mathrm{Se}$, the measured $7/{2}_{1}^{+}$ lifetime limit indicates a very small contribution of the $\ensuremath{\nu}1{g}_{7/2}$ configuration to the wave function of this state.

L. Pellegri et al. ; 5 pags. ; 6 figs. ; open access article under the CC BY license. Funded by SCOAP3, © 2014 The Authors. The γ decay from the high-lying states of 124Sn was measured using the inelastic scattering of 17O at 340 MeV. The emitted γ rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented δE-E silicon telescopes. The angular distribution was measured both for the γ rays and the scattered 17O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with (γ, γ') and (α, α'γ) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1- excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density., Grant No. 2011/03/B/ST2/01894; (iii) the National Superconducting Cyclotron Laboratory at MSU; (iv) the US NSF Grant PHY-1204486; and the German BMBF under Grant 06KY9136.

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-Gatermann, C; Napoli, D; Pearson, CJ; Podolyak, Z; Pollarolo, G; Pullia, A; Queiser, M; Recchia, F; Regan, PH; Regis, JM; Saed-Samii, N; Sahin, E; Scarlassara, F; Seidlitz, M; Siebeck, B; Sletten, G; Smith, JF; Soderstrom, PA; Stefanini, AM; Stezowski, O; Szilner, S; Szpak, B; Teng, R; Ur, C; Warner, DD; Wolf, K; Wu, CY; Zell, KO | Abstract: The transitional nuclei Xe132 and Xe133 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe136+Pb208 MNT reactions employing the high-resolution Advanced GAmma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (ii) in the Xe136+Pt198 MNT reaction employing the GAMMASPHERE spectrometer in combination with the gas-detector array CHICO, and (iii) as an evaporation residue after a Te130(α,xn)Xe134-xn fusion-evaporation reaction employing the HORUS γ-ray array at the University of Cologne. The high-spin level schemes are considerably extended above the Jπ=(7-) and (10+) isomers in Xe132 and above the 11/2- isomer in Xe133. The results are compared to the high-spin systematics of the Z=54 as well as the N=78 and N=79 chains. Furthermore, evidence is found for a long-lived (T1/2â‰1μs) isomer in Xe133 which closes a gap along the N=79 isotones. Shell-model calculations employing the SN100PN and PQM130 effective interactions reproduce the experimental findings and provide guidance to the interpretation of the observed high-spin features.

The structure of the S33 nucleus was investigated in the Mg24(N14,αp) fusion-evaporation reaction using a 40-MeV N14 beam. The level scheme was extended up to an excitation energy of 11.7 MeV and spin 19/2+. Lifetimes of the intermediate- and high-spin states have been investigated by the Doppler shift attenuation method. Data were compared with different shell-model calculations where effective interactions involving two main shells, the sd and the fp, are used.

The neutron-rich nucleus \nucleus{200}{Pt} is investigated via in-beam \gamma-ray spectroscopy in order to study the shape evolution in the neutron-rich platinum isotopes towards the N = 126 shell closure. The two-neutron transfer reaction \nucleus{198}{Pt}(\nucleus{82}{Se}, \nucleus{80}{Se})\nucleus{200}{Pt} is used to populate excited states of \nucleus{200}{Pt}. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects \gamma rays coincident with the \nucleus{80}{Se} recoils, the binary partner of \nucleus{200}{Pt}. The binary partner method is applied to extract the \gamma-ray transitions and build the level scheme of \nucleus{200}{Pt}. The level at 1884\,keV reported by Yates et. al [Phys. Rev. C 37, 1889] was confirmed to be at 1882.1\,keV and assigned as the (6^+_1) state. An additional \gamma ray was found and it presumably de-excites the (8^+_1) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even \nucleus{190-204}{Pt} isotopes, revealing that \nucleus{200}{Pt} marks the transition from the \gamma-unstable behaviour of lighter Pt nuclei towards a more spherical one when approaching the N=126 shell closure.

The Advanced GAmma Tracking Array (AGATA) has been installed at the GANIL facility, Caen-France. This setup exploits the stable and radioactive heavy-ions beams delivered by the cyclotron accelerator complex of GANIL. Additionally, it benefits from a large palette of ancillary detectors and spectrometers to address in-beam γ-ray spectroscopy of exotic nuclei. The set-up has been designed to couple AGATA with a magnetic spectrometer, charged-particle and neutron detectors, scintillators for the detection of high-energy γ rays and other devices such as a plunger to measure nuclear lifetimes. In this paper, the design and the mechanical characteristics of the set-up are described. Based on simulations, expected performances of the AGATA l π array are presented. Title in WoS: Conceptual design of the AGATA 1 pi array at GANIL

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 systematics for the N = 81 isotones. Its half-life is measured to be 8.6(10) ns, corresponding to a transition probability of B(E2; 19=2 ! 15=2 ) = 0:539(69) W.u. Latest shell model calculations considering 132Sn as a closed core reproduce the experimental findings and provide guidance to the interpretation of the new levels. The experimentally deduced reduced quadrupole transition probabilities of the isomeric states are compared to shell-model predictions.

The isovector giant dipole resonance (IVGDR) $\ensuremath{\gamma}$ decay was measured in the compound nuclei $^{80}\mathrm{Zr}$ and $^{81}\mathrm{Rb}$ at an excitation energy of ${E}^{*}=54$ MeV. The fusion reaction $^{40}\mathrm{Ca}+^{40}\mathrm{Ca}$ at ${E}_{\mathrm{beam}}=136$ MeV was used to form the compound nucleus $^{80}\mathrm{Zr}$, while the reaction $^{37}\mathrm{Cl}+^{44}\mathrm{Ca}$ at ${E}_{\mathrm{beam}}=95$ MeV was used to form the compound nucleus $^{81}\mathrm{Rb}$ at the same excitation energy. The IVGDR parameters extracted from the analysis were compared with the ones found at higher excitation energy (${E}^{*}=83$ MeV). The comparison allows one to observe two different nuclear mechanisms: (i) the IVGDR intrinsic width remains constant with the excitation energy in the nucleus $^{81}\mathrm{Rb}$; (ii) the isospin-violating spreading width (i.e., Coulomb spreading width) remains constant with the excitation energy in the nucleus $^{80}\mathrm{Zr}$. The experimental setup used for the $\ensuremath{\gamma}$-ray detection was composed by the AGATA demonstrator array coupled to the large-volume ${\mathrm{LaBr}}_{3}$:Ce detectors of the ${\mathrm{HECTOR}}^{+}$ array.

EXILL experimental campaign; International audience; The level scheme of 96Y was significantly extended and a new 201 ns isomer was located at 1655 keV excitation energy, with spin-parity assignment of 5± or 6−. The isomer decays to spherical low-spin structure by transitions with large hindrance and is fed by a short cascade which resembles the beginning of a rotational band. This is in analogy with the feeding and decay pattern of the 4− isomer in 98Y, here confirmed, by lifetime analysis, as a bandhead of a rotational structure with sizable deformation. It is suggested that the new isomer in 96Y arises from a shape change between deformed and spherical configurations, which indicates the appearance of deformation already at N = 57 in the yttrium chain. The experimental findings for 96Y are strengthened by theoretical calculations based on the complex Excited Vampir model.

D. Ralet et al. -- 11 pags., 10 figs., 3 tabs., Background: In the neutron-rich A≈100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A=100 up to mass A=108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the γ ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a γ-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A=100 to A=108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: τ=29.7-9.1+11.3 ps for the 4+ state of Mo108 and τ=3.2-0.7+0.7 ps for the 6+ state of Mo102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A=100 to A=108 with a maximum reached at N=64. The transition probabilities decrease for Mo108 which may be related to its well-pronounced triaxial shape indicated by the calculations., This work was supported by the BMBF under Grants No. 05P09RDFN4, No. 05P12RDFN8, and No. 05P12PKFNE and by the LOEWE center HIC for FAIR. Part of this work was supported by the P2IO excellence center. This work was also supported by the European Community FP7–Capacities, ENSAR Contract No. 262010, by the Swedish Research Council under Contracts No. 2010-147, No. 2010-3694, No. 2011-5253, No. 2011-6127, and No. 2014-5558, by the IN2P3- GSI No. 02-42 collaboration, by the Science and Technology Facilities Council (STFC) and by MINECO, Spain, under Grant No. FPA2014-57196-C5, and Generalitat Valenciana, Spain, under Grant No. PROMETEOII/2014/019

International audience; A new segmented particle detector, SPIDER, has been designed to be used as an ancillary device with the GALILEO γ-ray spectrometer, as well as with other multi-detector γ-ray arrays that will be available at LNL in the future (e.g. AGATA). To commission the SPIDER-GALILEO experimental setup, a multi-step Coulomb excitation experiment was carried out with a 240 MeV beam of (66)Zn produced by the Tandem-XTU accelerator at INFN Laboratori Nazionali di Legnaro. The measured particle and γ-ray spectra are compared with the results of detailed GEANT4 simulations which used the Coulomb excitation cross sections, estimated with the computer code GOSIA, as an input. The preliminary results indicate that precise transition probabilities will be obtained which are essential for solving discrepancies reported in the literature for this nucleus.

A major task in experimental nuclear astrophysics is the measurement of cross sections of capture reactions. In the last years, the astrophysics group of NCSR “ Demokritos ” developed and used a method for conducting this kind of research using a 4 π NaI γ -detector. Of great importance in this method is the determination of the efficiency of the detector, which depends on the average multiplicity of the γ -cascade de-exciting the entry state of the produced nucleus. Two new experimental setups have been studied and are in course of installation at the Tandem Laboratory of the Institute of Nuclear and Particle Physics of NCSR “ Demokritos ” , that will provide the possibility for conducting this kind of experiments inhouse. The first one is a new 14x14 inches NaI detector and the second is the BGO Ball of the GASP setup. These detector setups as well as their potential experimental use will be described in detail.

International audience; The structure of the 131Sn nucleus was studied at the Institut LaueLangevin by prompt-delayed γ-ray spectroscopy across the 0.3 µs, 23/2− isomeric state at 4670 keV, following cold-neutron-induced fission of 235U and 241Pu targets. New γ-ray transitions are observed and the results are compared with theoretical calculations performed with the Hybrid Configuration Mixing Model. The latter suggests that the majority of the states can be well-described in terms of couplings between single-hole degrees of freedom and 132Sn core excitations, pointing to a robust neutron shell closure at N = 82.

© 2019 Jagellonian University. All Rights Reserved. The breaking of isospin symmetry caused by the Coulomb interaction can be measured by the study of E1 γ decay. The Isovector Giant Dipole Resonance (IVGDR) was measured in 60 Zn and 62 Zn at two different excitation energies E ∗ = 47 MeV and E ∗ = 58 MeV with the goal of deducing the isospin mixing term. A fusion–evaporation reaction, with a beam of 32 S and a target of 28 Si, was used to produce 60 Zn. We also produced the compound nucleus 62 Zn using the reaction 32 S + 30 Si. This last reaction is required because, for the produced nucleus, the statistical model analysis is much less sensitive to the isospin mixing, and this allows to extract the GDR parameters and use them for isospin mixing sensitive reaction populating neighboring nucleus with N = Z. The experimental setup was composed of GALILEO array (germanium detectors) coupled to the large-volume LaBr 3 :Ce detectors for the γ-rays measuring and by two ancillary arrays, EUCLIDES and the Neutron Wall for the detection of particles and neutrons, respectively. An overview on the ongoing analysis and on preliminary results is presented. ispartof: ACTA PHYSICA POLONICA B vol:50 issue:3 pages:481-486 ispartof: location:POLAND, Zakopane status: published

Position sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ - spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined.

The main objective of the Advanced GAmma Tracking Array (AGATA) is the investigation of the structure of exotic nuclei at the new generation of RIB facilities. As part of the preparatory phase for FAIR-NUSTAR, AGATA is going to be installed at the FRS fragmentation facility of the GSI centre for an experimental campaign to be performed in 2012 and 2013. Owing to its γ - ray tracking capabilities and the envisaged enhancement in resolving power, a series of in-flight γ - ray spectroscopy experiments are being planned. The present work describes the conceptual design of this first implementation of AGATA at GSI-FRS, and provides information about the expected performance figures. According to the characteristics of each particular experiment, it is foreseen that the target–array distance is adjusted in order to achieve the optimum compromise between detection efficiency and energy resolution, or to cover an specific angular range of the emitted electromagnetic radiation. Thus, a comprehensive Monte Carlo study of the detection sensitivity in terms of photopeak efficiency, resolution and peak-to-total ratio, as a function of the target–array distance is presented. Several configurations have been investigated, and MC-calculations indicate that a remarkable enhancement in resolving power can be achieved when double-cluster AGATA detectors are developed and implemented. Several experimental effects are also investigated. This concerns the impact of passive materials between the target and the array, the angular distribution of the detection efficiency and the influence of target thickness effects and transition lifetimes in the attainable detection sensitivity. A short overview on half-life measurements via lineshape effects utilizing AGATA is also presented.

The level structures of the N = 50 83As, 82Ge, and 81Ga isotones have been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA–PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the γ-ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N = 50 shell closure in the region of 78Ni ( Z = 28 ). The comparison of the experimental level schemes with the shell-model calculations yields an N = 50 energy gap value of 4.7(3) MeV at Z = 28 . This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell model calculations, does not support a weakening of the N = 50 shell gap down to Z = 28 .

During the AGATA campaign at GANIL, the neutron-deficient Sn region was populated via a multi-nucleon transfer reaction in order to directly measure the lifetime of the first excited states with a plunger device, providing complementary information to previous results obtained with Coulomb excitation experiments. The AGATA γ-ray array was used together with the VAMOS++ spectrometer to study the nuclei of interest. ispartof: Acta Physica Polonica B vol:48 issue:3 pages:331-336 ispartof: location:Zakopane: POLAND status: published

International audience; The decay of the one-proton valence nucleus 133Sb is studied usingthe cold-neutron induced fission of 235U and 241Pu targets. The experimentis performed at the ILL reactor in Grenoble, using a highly efficient HPGearray, also coupled to fast LaBr3(Ce) scintillators. High-spin excited statesabove the 16.6 s isomer are observed, and the lifetime of the 13/2+ and15/2+ states is measured by fast-timing techniques, revealing a complexnature of the wave functions. The experimental results are well-interpretedby a newly developed microscopic model which takes into account the couplingbetween the valence proton and excitations (both collective and noncollective)of the doubly magic 132Sn core.

K. Hadyńska-Kl¸ek et al. ; 7 pags., 3 figs., 2 tabs., Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42 were determined from E2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 02+ has been obtained and the role of triaxiality in the A∼40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time. © 2016 American Physical Society, Special gratitude goes to the INFN LNL and HIL Warsaw technical staff for their support and help, in particular, the accelerator crews for providing intense and good-quality 42Ca and 32S beams. K. H.-K. acknowledges support from the Research Council of Norway under the project Grant No. 213442. T. R. R. acknowledges computing time at GSI-Darmstadt and support from Spanish MINECO under Programa Ramon y Cajal 11420 and FIS-2014-53434-P, H. N. acknowledges support from Helmholtz Association through the Nuclear Astrophysics Virtual Institute NAVI (No. VH-VI-417). We also acknowledge the support by Generalitat Valenciana, Spain, under the grant PROMETEOII/2014/019 and by the FEDER funds of the European Commission (A. Gadea), Spanish Ministerio de Economía y Competitividad under Contract No. FPA2014-57196-C5 (A. J., A. Gadea), German Bundesministerium für Bildung und Forschung (BMBF) under Contract No. 05P12PKFNE TP4 (B. Birkenbach), the Polish National Science Centre under Projects No. DEC-2013/10/M/ST2/00427, No. DPN/N190/ AGATA/2009, No. 2011/03/B/ST2/01894, No. UMO- 2014/14/M/ST2/00738 (COPIN-INFN Collaboration), and No. 2015/17/B/ST2/01534.

The multipolarity of the main transition leading to the ground state in 210Bi was investigated using the angular correlations of γ rays. The analyzed γ -coincidence data were obtained from the 209Bi(n,γ )210Bi experiment performed at Institut Laue-Langevin Grenoble at the PF1B cold-neutron facility. The EXILL (EXOGAM at the ILL) multidetector array, consisting of 16 high-purity germanium detectors, was used to detect γ transitions. The mixing ratio of the 320-keV γ ray was defined by minimizing a multivariable χ2 function constructed from the coefficients of angular correlation functions for seven pairs of strong transitions in 210Bi. As a result, the almost pure M1 multipolarity of the 320-keV γ ray was obtained, with an E2 admixture of less than 0.6% only (95% confidence limit). Based on this multipolarity the neutron-capture cross section leading to the ground state in 210Bi, that decays in turn to radiotoxic 210Po, was determined to be within the limits 21.3(9) and 21.5(9) mb. This result is important for nuclear reactor applications.

We performed a γ -particle coincidence experiment for the 60Ni+116Sn system to investigate whether the population of the two-neutron pickup channel leading to 62Ni is mainly concentrated in the ground-state transition, as has been found in a previous work [D. Montanari et al., Phys. Rev. Lett. 113, 052501 (2014)]. The experiment has been performed by employing the PRISMA magnetic spectrometer coupled to theAdvanced Gamma Tracking Array (AGATA) demonstrator. The strength distribution of excited states corresponding to the inelastic, one- and two-neutron transfer channels has been extracted.We found that in the two-neutron transfer channel the strength to excited states corresponds to a fraction (less than 24%) of the total, consistent with the previously obtained results that the 2n channel is dominated by the ground-state to ground-state transition.

The low-spin structure of the 210Bi nucleus was investigated in the neutron capture experiment 209Bi(n,γ )210Bi performed at ILL Grenoble at the PF1B cold-neutron facility. By using the EXILL multidetector array, consisting of 46 high-purity germanium crystals, and γγ-coincidence technique, 64 primary γ rays were observed (40 new) and a total number of 70 discrete states (33 new) were located below the neutron binding energy in 210Bi. The analysis of the angular correlations of γ rays provided information about transitions multipolarities, which made it possible to confirm most of the previously known spin-parity assignments and helped establish new ones. The obtained experimental results were compared to shell-model calculations involving one-valence-proton, one-valence-neutron excitations outside the 208Pb core. It has been found that while up to the energy of ∼2 MeV each state observed in 210Bi has its calculated counterpart; at higher excitation energies some levels cannot be described by the valence particle couplings. These states may arise from couplings of valence particles to the 3− octupole phonon of the doubly magic 208Pb core and may serve as a testing ground for models which describe single particle-phonon excitations.

The γ decay from the high-lying states of ^140Ce excited via inelastic scattering of ^17O at a bombarding energy of 340 MeV was measured using the high-resolution AGATA-demonstrator array in coincidence with scattered ions detected in two segmented Δ E-E silicon detectors. Angular distributions of scattered ions and emitted γ rays were measured, as well as their differential cross sections. The excitation of 1^− states below the neutron separation energy is similar to the one obtained in reactions with the α isoscalar probe. The comparison between the experimental differential cross sections and the corresponding predictions using the distorted-wave Born approximation allowed us to extract the isoscalar component of identified 1^− pygmy states. For this analysis the form factor obtained by folding microscopically calculated transition densities and optical potentials was used.

Lifetimes of yrast and nonyrast states of Pd-102 populated via the Zr-92(C-13, 3n) reaction are measured by means of the recoil distance Doppler-shift technique with a Cologne plunger coupled to a GASP spectrometer. The event-by-event data accumulated at 24 plunger distances in the range of 0.1 mu m to 9 mm are analyzed using the differential decay curve method. The resulting B(E2) values of the gamma transitions depopulating yrast-band members up to the I-pi = 8(+) state are found to deviate significantly from the corresponding predictions of the E(5) critical-point symmetry.

A. Vogt et al. ; 12 págs.; 9 figs.; 1 tab., Detailed spectroscopic information on the N∼82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in Xe134 is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in Xe136+U238 and Xe136+Pb208 MNT reactions and (ii) as a fission product in the Xe136+U238 reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The Xe136+Pt198 MNT reaction was studied with the γ-ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in Xe134 on top of the two long-lived isomers are discovered based on γγ-coincidence relationships and information on the γ-ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of Xe134 is extended up to an excitation energy of 5.832 MeV with tentative spin-parity assignments up to 16+. Previous assignments of states above the 7- isomer are revised. Latest shell-model calculations employing two different effective interactions reproduce the experimental findings and support the new spin and parity assignments., The research leading to these results has received funding from the German BMBF under Contract No. 05P12PKFNE TP4, from the European Union Seventh Framework Programme FP7/2007–2013 under Grant Agreement 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, from the Bonn-Cologne Graduate School of Physics and Astronomy (BCGS), from the UK Science and Technology Facilities Council (STFC), and from the US National Science Foundation (NSF). 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.

Reduced quadrupole transition probabilities for low-lying transitions in neutron-rich Se-84,Se-86 are investigated with a recoil distance Doppler shift (RDDS) experiment. The experiment was perform ...

The isospin mixing was deduced in the compound nucleus Zr-80 at an excitation energy of E* = 54 MeV from the gamma decay of the giant dipole resonance. The reaction Ca-40 + Ca-40 at E-beam = 136 MeV was used to form the compound nucleus in the isospin I = 0 channel, while the reaction Cl-37 + Ca-44 at E-beam = 95 MeV was used as the reference reaction. The. rays were detected with the AGATA demonstrator array coupled with LaBr3:Ce detectors. The temperature dependence of the isospin mixing was obtained and the zero-temperature value deduced. The isospin-symmetry-breaking correction delta(C) used for the Fermi superallowed transitions was extracted and found to be consistent with beta-decay data.

Background: Identification of proton-neutron mixed-symmetric one-quadrupole phonon excitations (the 2(ms)(+) states) of atomic nuclei provides information on the isovector part of the residual nucleon-nucleon interaction. It was predicted that the 2(ms)(+) state of particular nuclei close to the U(5) limit of the interacting boson model, in particular Ba-140, should be considerably populated by alpha-transfer reactions [C. E. Alonso et al., Phys. Rev. C 78, 017301 (2008)]. Purpose: We aim at the identification of the 2(ms)(+) mixed-symmetry state (MSS) of radioactive Ba-140 and investigate its population by the alpha-transfer reaction as a suitable tool to selectively populate MSSs and as a potential new signature for its mixed-symmetric character. Method: A gamma-ray spectroscopy experiment was performed in inverse kinematics in order to populate the 2(ms)(+) state of Ba-140 by alpha-transfer from a C-nat target on Xe-136 beam ions. The population of the candidate for the 2(ms)(+) state of Ba-140 was measured relative to the population of the 2(1)(+) state. Results: The candidate for the 2(ms)(+) state of Ba-140 was populated by a transfer three times weaker than predicted. Another 2(+) state that can be ruled out as the MSS was in turn as strongly populated by the a transfer as predicted for the MSS. Conclusions: The relative population of 2(+) states by alpha-transfer cannot serve as a new signature for MSSs, since other 2(+) states are also strongly populated. Nevertheless, the substantial population of the MSS candidate of Ba-140 by alpha transfer qualifies this type of reaction as suitable tool to excite MSSs and study their electromagnetic decay properties.

Background: Nuclear structure information for the neutron-rich actinide nuclei is important since it is the benchmark for theoretical models that provide predictions for the heaviest nuclei. Purpose: gamma-ray spectroscopy of neutron-rich heavy nuclei in the actinide region. Method: Multinucleon-transfer reactions in Zn-70 + U-238 and Xe-136 + U-238 have been measured in two experiments performed at the INFN Legnaro, Italy. In the Zn-70 experiment the high-resolution HPGe Clover Array (CLARA) coupled to the magnetic spectrometer PRISMA was employed. In the Xe-136 experiment the high-resolution Advanced Gamma Tracking Array (AGATA) was used in combination with PRISMA and the Detector Array for Multinucleon Transfer Ejectiles (DANTE). Results: The ground-state band (g.s. band) of U-240 was measured up to the 20(+) level and a tentative assignment was made up to the (24(+)) level. Results from gamma gamma coincidence and from particle coincidence analyses are shown. Moments of inertia (MoI) show a clear upbend. Evidence for an extended first negative-parity band of U-240 is found. Conclusions: A detailed comparison with latest calculations shows best agreement with cranked relativistic Hartree-Bogoliubov (CRHB) calculations for the g.s. band properties. The negative-parity band shows the characteristics of a K-pi = 0 band based on an octupole vibration.

WOS: 000295765100014, The first implementation of the AGATA spectrometer consisting of five triple germanium detector clusters has been installed at Laboratori Nazionali di Legnaro, INFN. This setup has two major goals, the first one is to validate the gamma-tracking concept and the second is to perform an experimental physics program using the stable beams delivered by the Tandem-PIAVE-ALPI accelerator complex. A large variety of physics topics will be addressed during this campaign, aiming to investigate both neutron and proton-rich nuclei. The setup has been designed to be coupled with the large-acceptance magnetic-spectrometer PRISMA. Therefore, the in-beam prompt gamma rays detected with AGATA will be measured in coincidence with the products of multinucleon-transfer and deep-inelastic reactions measured by PRISMA. Moreover, the setup is versatile enough to host ancillary detectors, including the heavy-ion detector DANTE, the gamma-ray detector array HELENA, the Cologne plunger for lifetime measurements and the Si-pad telescope TRACE. In this paper the design; characteristics and performance figures of the setup will be described.