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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 42Ca 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 42Ca were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2 matrix elements coupling six low-lying states in 42Ca, including the diagonal E2 matrix elements of 2+ 1 and 2+ 2 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 0+ 1,2 and 2+ 1,2 states, as well as triaxiality for 0+ 1,2 states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in 42Ca. 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 42Ca.

The lifetimes of the first excited 2þ, 4þ, and 6þ states in 98Zr were measured with the recoil-distance Doppler shift method in an experiment performed at GANIL. Excited states in 98Zr were populated using the fission reaction between a 6.2 MeV=u 238U beam and a 9 Be target. The γ rays were detected with the EXOGAM array in correlation with the fission fragments identified by mass and atomic number in the VAMOS++ spectrometer. Our result shows a very small BðE2; 2þ 1 → 0þ 1 Þ value in 98Zr, thereby confirming the very sudden onset of collectivity at N ¼ 60. The experimental results are compared to large-scale Monte Carlo shell model and beyond-mean-field calculations. The present results indicate the coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.

Lifetimes of the first excited 2þ and 4þ states in the extremely neutron-deficient nuclide 172Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio BðE2∶4þ 1 → 2þ 1 Þ=BðE2∶2þ 1 → 0þ gsÞ ¼ 0.55ð19Þ was found, similar to a handful of other such anomalous cases observed in the entire Segr´e chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N ≈ 90–94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low BðE2∶4þ 1 → 2þ 1 Þ=BðE2∶2þ 1 → 0þ gsÞ ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of BðE2∶4þ 1 → 2þ 1 Þ=BðE2∶2þ 1 → 0þ gs) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N ≈ 90–94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.

20th IEEE Real Time Conference, 5–10 Haz 2016, Padova, Italy -- F.J. Egea is with INFN Sezione di Padova, Padova, Italy. E-mail: javiegea@pd.infn.it. -- V. González and E. Sanchis are with Departament d’Enginyeria Electrònica. Universitat de València. Burjassot (Spain). -- C. Houarner, A. Boujrad, M. Tripon and G. de France are with Grand Accélératéur National d’Ions Lourds (GANIL), Caen, France. -- A. Gadea and T. Hüyük are with Institut de Física Corpuscular (IFIC), Paterna, Spain. -- J.J. Valiente-Dobón and G. Jaworski are with LNL (Laboratori Nazionali di Legnaro), Legnaro, Italy. -- J. Nyberg is with Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden. -- M. Moszyński is with National Centre for Nuclear Research, A. Soltana 7, PL 05-400 Otwock-Swierk, Poland. -- M.N. Enduran is with Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University Istanbul, Turkey. -- S. Ertürk is with Nigde Universitesi, Fen-Edebiyat Falkultesi, Fizik Bölümü, Nigde, Turkey. -- M. Jastrząb is with the Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland. -- I. Lazarus is with STFC Daresbury Laboratory, Warrington, United Kingdom. -- P-A. Söderström is with RIKEN Nishina Center, Wako-shi, Japan. -- V. Modamio is with Universitet I Oslo, Oslo, Norway. -- X. L. Luo is with Department of Instrument Science and Technology, National University of Defense Technology, Changsha, China. -- M.Palacz are with the Heavy Ion Laboratory, University of Warsaw, Warszawa, Poland. -- R. Wadsworth is with Department of Physics, University of York, York, United Kingdom. The detection of rare events close to the proton dripline involve the utilization of high-efficient neutron detectors with excellent neutron-gamma discrimination (NGD) performance. Even though in the literature, several off-line algorithms focus on the maximization of the NGD accuracy, our aim is to look for an on-line efficient implementation capable to discard a majority of the gamma-rays, therefore allowing the system to work to counting rates up to 50 kHz, optimizing hence the overall electronics infrastructure in terms of data throughput. In this paper we analyze two of the most widespread techniques for NGD based on PSA, i.e. the charge-comparison method (CC) and the zero crossover (ZCO). Then, based on the NGD performance and FPGA resource utilization, we select one to be implemented in an FPGA. Finally we present the preliminary results obtained up to now.