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Author Tonev, D. et al; Gadea, A.
Title Transition probabilities in P-31 and S-31: A test for isospin symmetry Type Journal Article
Year (down) 2021 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 821 Issue Pages 136603 - 6pp
Keywords Mirror nuclei; Lifetime measurements; Transition probabilities; Isospin symmetry; Microscopic multiphonon model
Abstract Excited states in the mirror nuclei P-31 and S-31 were populated in the 1p and 1n exit channels of the reaction Ne-20 + C-12, at a beam energy of 33 MeV. The Ne-20 beam was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident gamma-rays and Doppler-shift attenuation lifetime measurements were performed using the multi-detector array GASP in conjunction with the EUCLIDES charged particle detector. In the observed B(E1) strengths, the isoscalar component, amounting to 24% of the isovector one, provides strong evidence for breaking of the isospin symmetry in the A = 31 mass region. Self-consistent beyond mean field calculations using Equation of Motion method based on a chiral potential and including two- and three-body forces reproduce well the experimental B(E1) strengths, reinforcing our conclusion. Coherent mixing from higher-lying states involving the Giant Isovector Monopole Resonance accounts well for the effect observed. The breaking of the isospin symmetry originates from the violation of the charge symmetry of the two- and three-body parts of the potential, only related to the Coulomb interaction.
Address [Tonev, D.; Goutev, N.; Pavlov, P.; Pantaleev, I. L.; Iliev, S.; Yavahchova, M. S.; Demerdjiev, A.; Dimitrov, D. T.; Geleva, E.; Laftchiev, H.] Bulgarian Acad Sci, Inst Nucl Res & Nucl Energy, BG-1784 Sofia, Bulgaria, Email: dimitar.tonev@inrne.bas.bg
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000734909800003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5064
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Author Bertoldo, S.; Maggioni, G.; Raniero, W.; Carraro, C.; Riccetto, S.; Sgarbossa, F.; Scarpa, D.; Andrighetto, A.; Mazzolari, A.; Gadea, A.; Napoli, D.R.; Napolitani, E.; De Salvador, D.
Title New method for the production of thin and stable, segmented n plus contacts in HPGe detectors Type Journal Article
Year (down) 2021 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A
Volume 57 Issue 6 Pages 177 - 10pp
Keywords
Abstract The realization of pulsed-laser diffused, thin n+ contacts on high purity germanium (HPGe) and their successful segmentation is described. The contacts have been obtained by a laser-induced diffusion of Sb atoms, deposited by sputtering on Ge surface, and then segmented by means of a photolithographic technique. Three small prototypes of gamma ray detectors have been implemented, using the same n+ contact (laser diffused Sb) but with three different geometries and a B implanted p+ contact. Electrical and detection properties of the prototypes have been characterized, showing low leakage currents and good spectroscopy data with different gamma-ray sources. The stability of the detector performance has also been tested subjecting one of the prototypes to a typical annealing treatment.
Address [Bertoldo, S.; Maggioni, G.; Raniero, W.; Carraro, C.; Sgarbossa, F.; Scarpa, D.; Andrighetto, A.; Napoli, D. R.; Napolitani, E.; De Salvador, D.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, Viale Univ 2, I-35020 Legnaro, PD, Italy, Email: maggioni@lnl.infn.it
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6001 ISBN Medium
Area Expedition Conference
Notes WOS:000781800800001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5193
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Author Fernandez, A.; Hufschmidt, D.; Colaux, J.L.; Valiente-Dobon, J.J.; Godinho, V.; Jimenez de Haro, M.C.; Feria, D.; Gadea, A.; Lucas, S.
Title Low gas consumption fabrication of He-3 solid targets for nuclear reactions Type Journal Article
Year (down) 2020 Publication Materials & Design Abbreviated Journal Mater. Des.
Volume 186 Issue Pages 108337 - 10pp
Keywords He-3 solid targets; Quasistatic magnetron sputtering; Low gas consumption; Nuclear reactions; Inverse kinematics; Target stability
Abstract Nanoporous solids that stabilize trapped gas nanobubbles open new possibilities to fabricate solid targets for nuclear reactions. A methodology is described based on the magnetron sputtering (MS) technique operated under quasistatic flux conditions to produce such nanocomposites films with He-3 contents of up to 16 at.% in an amorphous-silicon matrix. In addition to the characteristic low pressure (3-6 Pa) needed for the gas discharge, the method ensures almost complete reduction of the process gas flow during film fabrication. The method could produce similar materials to those obtained under classical dynamic flux conditions for MS. The drastic reduction (>99.5%) of the gas consumption is fundamental for the fabrication of targets with scarce and expensive gases. Si:He-3 and W:He-3 targets are presented together with their microstructural (scanning and transmission electron microscopy, SEM and TEM respectively) and compositional (Ion Beam Analysis, IBA) characterization. The He-3 content achieved was over 1 x 10(18) at/cm(2) for film thicknesses between 1.5 and 3 μm for both Si and W matrices. First experiments to probe the stability of the targets for nuclear reaction studies in inverse kinematics configurations are presented.
Address [Fernandez, Asuncion; Hufschmidt, Dirk; Godinho, Vanda; Jimenez de Haro, Maria C.; Feria, David] Univ Seville, CSIC, Inst Ciencia Mat Sevilla, Avda Amer Vespucio 49, Seville 41092, Spain, Email: asuncion@icmse.csic.es
Corporate Author Thesis
Publisher Elsevier Sci Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0264-1275 ISBN Medium
Area Expedition Conference
Notes WOS:000505221700053 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4239
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Author Ljungvall, J.; Perez-Vidal, R.M.; Lopez-Martens, A.; Michelagnoli, C.; Clement, E.; Dudouet, J.; Gadea, A.; Hess, H.; Korichi, A.; Labiche, M.; Lalovic, N.; Li, H.J.; Recchia, F.
Title Performance of the Advanced GAmma Tracking Array at GANIL Type Journal Article
Year (down) 2020 Publication Nuclear Instruments & Methods in Physics Research A Abbreviated Journal Nucl. Instrum. Methods Phys. Res. A
Volume 955 Issue Pages 163297 - 13pp
Keywords AGATA spectrometer; GANIL facility; gamma-ray tracking; Nuclear structure; HPGe detectors
Abstract The performance of the Advanced GAmma Tracking Array (AGATA) at GANIL is discussed, on the basis of the analysis of source and in-beam data taken with up to 30 segmented crystals. Data processing is described in detail. The performance of individual detectors are shown. The efficiency of the individual detectors as well as the efficiency after gamma-ray tracking are discussed. Recent developments of gamma-ray tracking are also presented. The experimentally achieved peak-to-total is compared with simulations showing the impact of back-scattered gamma rays on the peak-to-total in a gamma-ray tracking array. An estimate of the achieved position resolution using the Doppler broadening of in-beam data is also given. Angular correlations from source measurements are shown together with different methods to take into account the effects of gamma-ray tracking on the normalization of the angular correlations.
Address [Ljungvall, J.; Lopez-Martens, A.; Dudouet, J.; Korichi, A.] Univ Paris Saclay, Univ Paris Sud, CNRS IN2P3, CSNSM, F-91405 Orsay, France, Email: joa.ljungvall@csnsm.in2p3.fr
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0168-9002 ISBN Medium
Area Expedition Conference
Notes WOS:000508940400029 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4276
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Author AGATA Collaboration (Cederwall, B. et al); Gadea, A.; Jurado, M.; Domingo-Pardo, C.; Huyuk, T.; Perez-Vidal, R.M.
Title Isospin Properties of Nuclear Pair Correlations from the Level Structure of the Self-Conjugate Nucleus Ru-88 Type Journal Article
Year (down) 2020 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.
Volume 124 Issue 6 Pages 062501 - 6pp
Keywords
Abstract The low-lying energy spectrum of the extremely neutron-deficient self-conjugate (N = Z) nuclide Ru-88(44)44 has been measured using the combination of the Advanced Gamma Tracking Array (AGATA) spectrometer, the NEDA and Neutron Wall neutron detector arrays, and the DIAMANT charged particle detector array. Excited states in Ru-88 were populated via the Fe-54(Ar-36, 2n gamma)Ru-88* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. The observed gamma-ray cascade is assigned to Ru-88 using clean prompt gamma-gamma-2-neutron coincidences in anticoincidence with the detection of charged particles, confirming and extending the previously assigned sequence of low-lying excited states. It is consistent with a moderately deformed rotating system exhibiting a band crossing at a rotational frequency that is significantly higher than standard theoretical predictions with isovector pairing, as well as observations in neighboring N > Z nuclides. The direct observation of such a “delayed” rotational alignment in a deformed N = Z nucleus is in agreement with theoretical predictions related to the presence of strong isoscalar neutron-proton pair correlations.
Address [Cederwall, B.; Liu, X.; Aktas, O.; Ertoprak, A.; Zhang, W.; Qi, C.; Nyberg, A. Atac; Back, T.; Doncel, M.; Gottardo, A.] KTH Royal Inst Technol, S-10691 Stockholm, Sweden, Email: cederwall@nuclear.kth.se
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007 ISBN Medium
Area Expedition Conference
Notes WOS:000513242500002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4278
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Author AGATA Collaboration (Korten, W. et al); Gadea, A.
Title Physics opportunities with the Advanced Gamma Tracking Array: AGATA Type Journal Article
Year (down) 2020 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A
Volume 56 Issue 5 Pages 137 - 33pp
Keywords
Abstract New physics opportunities are opening up by the Advanced Gamma Tracking Array, AGATA, as it evolves to the full 4 pi instrument. AGATA is a high-resolution gamma -ray spectrometer, solely built from highly segmented high-purity Ge detectors, capable of measuring gamma rays from a few tens of keV to beyond 10 MeV, with unprecedented efficiency, excellent position resolution for individual gamma -ray interactions, and very high count-rate capability. As a travelling detector AGATA will be employed at all major current and near-future European research facilities delivering stable and radioactive ion beams.
Address [Clement, E.] CEA DRF CNRS IN2P3, GANIL, Bd Henri Becquerel,BP 55027, F-14076 Caen 05, France, Email: w.korten@cea.fr
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6001 ISBN Medium
Area Expedition Conference
Notes WOS:000537289700004 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4422
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Author Siciliano, M. et al; Gadea, A.
Title Shape coexistence in neutron-deficient Hg-188 investigated via lifetime measurements Type Journal Article
Year (down) 2020 Publication Physical Review C Abbreviated Journal Phys. Rev. C
Volume 102 Issue 1 Pages 014318 - 16pp
Keywords
Abstract Background: Shape coexistence in the Z approximate to 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 Hg-188 isotope. Purpose: The aim of this work was to measure lifetimes of excited states in Hg-188 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 Hg-188 nucleus was populated using two different fusion-evaporation reactions with two targets, Gd-158 and Gd-160, and a beam of S-34 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 gamma rays were detected using the GALILEO gamma-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 16 (h) over bar 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 Hg-188 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 12(1)(+) 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.
Address [Siciliano, M.; Zanon, I; Cicerchia, M.; de Angelis, G.; Galtarossa, F.; Gozzelino, A.; Hadynska-Klek, K.; Jaworski, G.; Napoli, D. R.; Valiente-Dobon, J. J.] INFN, Lab Nazl Legnaro, I-35020 Legnaro, Italy, Email: marco.siciliano@lnl.infn.it
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0556-2813 ISBN Medium
Area Expedition Conference
Notes WOS:000551404600001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4471
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Author AGATA Collaboration (Siciliano, M. et al); Gadea, A.; Perez-Vidal, R.M.; Domingo-Pardo, C.
Title Pairing-quadrupole interplay in the neutron-deficient tin nuclei: First lifetime measurements of low-lying states in Sn-106,Sn-108 Type Journal Article
Year (down) 2020 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 806 Issue Pages 135474 - 7pp
Keywords Lifetime; Nuclear structure; Multi-nucleon transfer; Light Sn; Tracking array
Abstract 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.
Address [Siciliano, M.; Valiente-Dobon, J. J.; Goasduff, A.; Jaworski, G.; Marchi, T.; Napoli, D. R.; Saygi, B.; Egea-Canet, F. J.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, Legnaro, PD, Italy, Email: marco.siciliano@lnl.infn.it
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000571760900006 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4539
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Author Ertoprak, A. et al; Algora, A.; Gadea, A.; Huyuk, T.
Title Lifetimes of core-excited states in semi-magic Rh-95 Type Journal Article
Year (down) 2020 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A
Volume 56 Issue 11 Pages 291 - 8pp
Keywords
Abstract Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus Rh-95. The fusion-evaporation reaction Ni-58(Ca-40, 3p) was used to populate high-spin states in Rh-95 at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6 mg/cm(2) metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations. state-of-the-art theory. Remarkably, the structural features up to moderate angular momentum of nuclei immediately below the N = Z = 50 shell closures can be described with high accuracy in a very simple way by shell-model calculations including only the g(9/2) and p(1/2) subshells. Of special interest is the neutron-proton pair coupling scheme which is expected to appear in the heaviest N=Z nuclei [1,2] and the seniority structure of the N = 50 isotones [3-7]. However, multiple core-excited states have been observed in the semi-magic nuclei of the Sn-100 region [8-10]. The theoretical study of those states is a challenging task, which requires a significantly larger model space for their interpretation. Transition probabilities between nuclear states provide important constraints for theoretical modelling of the structure of the nuclei of interest. Our previous lifetime study of the semimagic (N = 50) nucleus Ru-94 [ 11,12] provided information on the electromagnetic decay properties of neutron-core excited states. We now address lifetime measurements in its closest, more neutron deficient, isotone Rh-95 using the same DSAM technique. The experimental results have been interpreted within the framework of large-scale shell-model (LSSM) calculations.
Address [Ertoprak, A.; Qi, C.; Cederwall, B.; Doncel, M.; Jakobsson, U.; Atac, A.; Back, T.; Ghazi Moradi, F.; Li, H.] Royal Inst Technol KTH, Dept Phys, S-10691 Stockholm, Sweden, Email: ertoprak@kth.se
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6001 ISBN Medium
Area Expedition Conference
Notes WOS:000590264900001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4612
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Author AGATA Collaboration (Avigo, R. et al); Domingo-Pardo, C.; Gadea, A.; Gonzalez, V.
Title Low-lying electric dipole gamma-continuum for the unstable Fe-62(,)64 nuclei: Strength evolution with neutron number Type Journal Article
Year (down) 2020 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 811 Issue Pages 135951 - 6pp
Keywords Fe-64; Fe-62; Nuclear structure; Dipole excitation around neutron threshold
Abstract The gamma-ray emission from the nuclei Fe-62,Fe-64 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-62,Fe-64 were produced at the FAIR-GSI laboratories and selected with the FRS spectrometer. The gamma decay was detected with AGATA. From the measured gamma-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.
Address [Avigo, R.; Wieland, O.; Bracco, A.; Camera, F.; Benzoni, G.; Blasi, N.; Bottoni, S.; Brambilla, S.; Crespi, F. C. L.; Leoni, S.; Million, B.; Morales, A., I; Pullia, A.; Riboldi, S.] Ist Nazl Fis Nucl, Sez Milano, I-20133 Milan, Italy, Email: oliver.wieland@mi.infn.it
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000612225400080 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4700
Permanent link to this record