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Author |
Siciliano, M. et al; Gadea, A. |
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Title |
Shape coexistence in neutron-deficient Hg-188 investigated via lifetime measurements |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
102 |
Issue |
1 |
Pages |
014318 - 16pp |
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Keywords |
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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. |
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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 |
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Amer Physical Soc |
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English |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
0556-2813 |
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Conference |
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Notes |
WOS:000551404600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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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. |
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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 |
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Year |
2020 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
806 |
Issue |
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Pages |
135474 - 7pp |
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Keywords |
Lifetime; Nuclear structure; Multi-nucleon transfer; Light Sn; Tracking array |
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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. |
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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 |
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Publisher |
Elsevier |
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English |
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Series Volume |
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Edition |
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ISSN |
0370-2693 |
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Conference |
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Notes |
WOS:000571760900006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4539 |
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Author |
AGATA Collaboration (Sahin, E. et al); Gadea, A.; Huyuk, T. |
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Title |
Shell evolution beyond N=40: Cu-69,Cu-71,Cu-73 |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
91 |
Issue |
3 |
Pages |
034302 - 9pp |
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Keywords |
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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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Address |
[Sahin, E.; de Angelis, G.; Modamio, V.; Valiente-Dobon, J. J.; Corradi, L.; Fioretto, E.; Gottardo, A.; Montanari, D.; Napoli, D. R.; Rosso, D.; Singh, Pushpendra P.; Stefanini, A. M.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, I-35020 Legnaro, Italy |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000350998600002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2159 |
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Author |
Sahin, E. et al; Gadea, A.; Algora, A. |
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Title |
Structure of the N=50 As, Ge, Ga nuclei |
Type |
Journal Article |
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Year |
2012 |
Publication |
Nuclear Physics A |
Abbreviated Journal |
Nucl. Phys. A |
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Volume |
893 |
Issue |
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Pages |
1-12 |
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Keywords |
NUCLEAR REACTIONS U-238(Se-82, Ga-81), (Se-82, Ge-82), (Se-82, As-83), E=515 MeV; measured E-gamma, I-gamma (theta), gamma gamma-coin, reaction fragments, (fragment)gamma-coin using PRISMA magnetic spectrometer, gamma after deexcitation using Ge Compton-suppressed detectors of CLARA array, thin and thick target; deduced sigma(theta), levels, J, pi; calculated levels, J, pi using shell model |
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Abstract |
The level structures of the N = 50 As-83, Ge-82, and Ga-81 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 gamma-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 Ni-78 (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. |
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Address |
[Sahin, E.; de Angelis, G.; Gadea, A.; Corradi, L.; Fioretto, E.; Gottardo, A.; Guiot, B.; Modamio, V.; Napoli, D. R.; Silvestri, R.; Stefanini, A. M.; Valiente-Dobon, J. J.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, I-35020 Legnaro, Italy, Email: eda.sahin@lnl.infn.it |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0375-9474 |
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Conference |
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Notes |
WOS:000310091000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1191 |
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Author |
AGATA Collaboration (Rezynkina, K. et al); Gadea, A.; Perez-Vidal, R.M. |
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Title |
Structure of As-83, As- 85, and As-87: From semimagicity to gamma softness |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
106 |
Issue |
1 |
Pages |
014320 - 14pp |
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Keywords |
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Abstract |
The structure of As-83,As- 85, and As-87 have been studied in fusion-fission reaction( 238)U+9Be. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident gamma rays were detected in the gamma-ray tracking array AGATA. New transitions in 83As and 85As are reported and placed in the level schemes. A level scheme of the excited states in 87As is proposed for the first time. The data are interpreted in frame of large-scale shell-model calculations, SU3 symmetries, and beyond mean-field frameworks. A spherical regime at magic number N = 50 is predicted and the location of the proton g9/2 orbital is proposed for the first time. Development of collectivity in a prolate deformed, gamma-soft regime in the open shell cases 85As and 87As, most neutron-rich isotopes beyond N = 50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the 9/2+ state in 79Cu, one proton above 78Ni. |
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Address |
[Rezynkina, K.; Dao, D. D.; Duchene, G.; Nowacki, F.; Didierjean, F.; Le Blanc, F.; Lozeva, R.; Schmitt, C.] Univ Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France, Email: kseniia.rezynkina@pd.infn.it |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000848175600004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5347 |
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