| 1. |
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| 2. |
- Boso, A., et al.
(författare)
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Isospin dependence of electromagnetic transition strengths among an isobaric triplet
- 2019
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Ingår i: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 797
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Tidskriftsartikel (refereegranskat)abstract
- Electric quadrupole matrix elements, M-p, for the J(pi) = 2(+) -> 0(+), Delta T = 0, T = 1 transitions across the A = 46 isobaric multiplet Cr-46-V-46-Ti-46 have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of M-p with respect to T-z. Pairs of nuclei in the T = 1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The M-p values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for Cr-46 and Ti-46; (ii) a "stretched target" technique was adopted here, for the first time, for lifetime measurements in V-46 and Ti-46. A constant value of M-p across the triplet has been observed. Shell-model calculations performed within the fp shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T = 1 isospin triplets is presented. (C) 2019 The Author(s). Published by Elsevier B.V.
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| 3. |
- Louchart, C., et al.
(författare)
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Collective nature of low-lying excitations in Zn-70,Zn-72,Zn-74 from lifetime measurements using the AGATA spectrometer demonstrator
- 2013
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neutron-rich nuclei with protons in the fp shell show an onset of collectivity around N=40. Spectroscopic information is required to understand the underlying mechanism and to determine the relevant terms of the nucleon-nucleon interaction that are responsible for the evolution of the shell structure in this mass region. Methods: We report on the lifetime measurement of the first 2(+) and 4(+) states in Zn-70,Zn-72 ,Zn-74 and the first 6(+) state in Zn-72 using the recoil distance Doppler shift method. The experiment was carried out at the INFN Laboratory of Legnaro with the AGATA demonstrator, first phase of the Advanced Gamma Tracking Array of highly segmented, high-purity germanium detectors coupled to the PRISMA magnetic spectrometer. The excited states of the nuclei of interest were populated in the deep inelastic scattering of a Ge-76 beam impinging on a U-238 target. Results: The maximum of collectivity along the chain of Zn isotopes is observed for Zn-72 at N=42. An unexpectedly long lifetime of 20(-5.2)(+1.8) ps was measured for the 4(+) state in Zn-74. Conclusions: Our results lead to small values of the B(E2;4(1)(+) -> 21(+))/B(E2;2(1)(+->)0(1)(+)) ratio for Zn-72,Zn-74, suggesting a significant noncollective contribution to these excitations. These experimental results are not reproduced by state-of-the-art microscopic models and call for lifetime measurements beyond the first 2(+) state in heavy zinc and nickel isotopes.
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| 4. |
- Sahin, E., et al.
(författare)
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Shell evolution beyond N=40 : Cu-69,Cu-71,Cu-73
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:3
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Tidskriftsartikel (refereegranskat)abstract
- The level structure of the neutron-rich Cu-69, Cu-71, and Cu-73 isotopes has been investigated by means of multinucleon transfer reactions. The experiment was performed at Laboratori Nazionali di Legnaro using the AGATA Demonstrator array coupled to the PRISMA magnetic spectrometer. Lifetimes of excited states in Cu nuclei were measured with the recoil-distance Doppler-shift method. The resulting electromagnetic matrix elements for transitions from excited states in Cu-69,Cu-71,Cu-73 nuclei are used to assess the collective or single-particle character of these states. The results are compared with predictions of large-scale shell-model calculations, giving further insight into the evolution of the proton pf shell as neutrons fill the 1g(9/2) orbital.
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| 5. |
- Doncel, Maria, et al.
(författare)
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Lifetime Measurements in Neutron-rich Cu Isotopes
- 2013
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 44:3, s. 505-510
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of neutron-rich nuclei close to the double-magic nucleus Ni-78 has been investigated by measuring the lifetime of excited states. In this contribution, it will be presented the lifetime of the J(pi) = 7/2(-) excited state at 981 keV of the Cu-71 isotope, measured using the AGATA Demonstrator coupled to the PRISMA spectrometer and the Koln plunger setup. This is the first time this combined setup has been used for a lifetime measurement.
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| 6. |
- Alexander, T., et al.
(författare)
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Isomeric Ratios in 206Hg
- 2015
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 46:3, s. 601-605
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Tidskriftsartikel (refereegranskat)abstract
- Hg-206 was populated in the fragmentation of an E/A = 1 GeV Pb-208 beam at GSI. It was part of a campaign to study nuclei around Pb-208 via relativistic Coulomb excitation. The observation of the known isomeric states confirmed the identification of the fragmentation products. The isomeric decays were also used to prove that the correlations between beam identification detectors and the AGATA gamma-ray tracking array worked properly and that the tracking efficiency was independent of the time relative to the prompt flash.
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| 7. |
- Podolyák, Zs, et al.
(författare)
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Role of the Δ Resonance in the Population of a Four-Nucleon State in the 56Fe → 54Fe Reaction at Relativistic Energies
- 2016
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Ingår i: Physical Review Letters. - 0031-9007. ; 117:22
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Tidskriftsartikel (refereegranskat)abstract
- The Fe54 nucleus was populated from a 56Fe beam impinging on a Be target with an energy of E/A=500 MeV. The internal decay via γ-ray emission of the 10+ metastable state was observed. As the structure of this isomeric state has to involve at least four unpaired nucleons, it cannot be populated in a simple two-neutron removal reaction from the 56Fe ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of 54Fe, suggesting that it was populated via the decay of the Δ0 resonance into a proton. This process allows the population of four-nucleon states, such as the observed isomer. Therefore, it is concluded that the observation of this 10+ metastable state in 54Fe is a consequence of the quark structure of the nucleons.
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| 8. |
- Hagen, T. W., et al.
(författare)
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Evolution of nuclear shapes in odd-mass yttrium and niobium isotopes from lifetime measurements following fission reactions
- 2017
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Ingår i: Physical Review C: covering nuclear physics. - 2469-9985. ; 95:3
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of excited states in Y99,Y101,Nb101,Nb103, and Nb105 were measured in an experiment using the recoil distance Doppler shift method at GANIL (Grand Accélérateur National d'Ions Lourds). The neutron-rich nuclei were produced in fission reactions between a U238 beam and a Be9 target. Prompt γ rays were measured with the EXOGAM array and correlated with fission fragments that were identified in mass and atomic number with the VAMOS++ spectrometer. The measured lifetimes, together with branching ratios, provide B(M1) and B(E2) values for the strongly coupled rotational bands built on the [422]5/2+ ground state in the Y and Nb nuclei with neutron number N≥60. The comparison of the experimental results with triaxial particle-rotor calculations provides information about the evolution of the nuclear shape in this mass region.
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| 9. |
- Hauge, J. M. Baalsrud, et al.
(författare)
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Game Mechanics Supporting Pervasive Learning and Experience in Games, Serious Games, and Interactive & Social Media
- 2015
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Ingår i: ENTERTAINMENT COMPUTING (ICEC 2015). - Cham : Springer. - 9783319245898 - 9783319245881 ; , s. 560-565
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Konferensbidrag (refereegranskat)abstract
- This workshop investigates the mechanisms for behaviour change and influence, focusing on the definition of requirements for pervasive gameplay and interaction mechanics, procedures, actions, mechanisms, systems, story, etc.) with the purpose of informing, educating, reflecting and raising awareness. By connecting various experts such as designers, educators, developers, evaluators and researchers from both industry and academia, this workshop aims to enable participants share, discuss and learn about existing relevant mechanisms for pervasive learning in a Serious Game (SG) context. Research in SG, as a whole, faces two main challenges in understanding: the transition between the instructional design and actual game design implementation [1] and documenting an evidence-based mapping of game design patterns onto relevant pedagogical patterns [2]. From a practical perspective, this transition lacks methodology and requires a leap of faith from a prospective customer to the ability of a SG developer to deliver a game that will achieve the desired learning outcomes. This workshop aims to present and apply a preliminary exposition though a purpose-processing methodology to probe, from various SG design aspects, how SG design patterns map with pedagogical practices
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| 10. |
- Lalovic, Natasa, et al.
(författare)
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Analysis of the Response of AGATA Detectors at GSI
- 2015
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759817948 ; 93, s. 07007-07007
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Konferensbidrag (refereegranskat)abstract
- In 2012 and 2014 the γ-ray tracking spectrometer AGATA was operated at the SIS/FRS facility at GSI in Darmstadt, Germany. The performance of the array is discussed, outlining some important aspects of the offline data processing and analysis. Relying on the data obtained from measurements with standard γ-ray sources, a first estimate of the photopeak efficiency and peak-to-total (P/T) is presented.
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