| 1. |
- Boso, A., et al.
(author)
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Isospin dependence of electromagnetic transition strengths among an isobaric triplet
- 2019
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In: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 797
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Journal article (peer-reviewed)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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| 2. |
- Gadea, A., et al.
(author)
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Observation of Ni-54 : Cross-conjugate symmetry in f(7/2) mirror energy differences
- 2006
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:15, s. 152501-
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Journal article (peer-reviewed)abstract
- Gamma decays from excited states up to J(pi)=6(+) in the N=Z-2 nucleus Ni-54 have been identified for the first time. Level energies are compared with those of the isobars Co-54 and Fe-54 and of the cross-conjugate nuclei of mass A=42. The good but puzzling f(7/2) cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.
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| 3. |
- Georgali, E., et al.
(author)
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Experimental study of the 165Ho(n, 2n) reaction : Cross section measurements for the population of the 164Ho ground state and isomeric state from the threshold up to 20 MeV
- 2020
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 102:3
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Journal article (peer-reviewed)abstract
- In the present work the 165Ho(n,2n) reaction was studied experimentally and theoretically for the population of the ground state (Jπ=1+) of the 164Ho product nucleus, as well as for the population of its isomeric state (Eex=139.8 keV, Jπ=6−). The cross sections of both the ground and isomeric state channels were measured at energies near the reaction threshold (Eth=8.04 MeV), at 10.1, 10.4, and 10.7 MeV, as well as at energies higher than 17 MeV, at 17.1, 18.1, 19.0, and 19.6 MeV. The adopted method was the activation technique relative to the 197Au(n,2n) 196Au and 27Al(n,α)24Na reference reactions. The quasi-monoenergetic neutron beams for the near threshold energies were produced via the 2H(d,n)3He reaction, while for the neutron beams above 17 MeV the 3H(d,n)4He reaction was utilized. In both cases the deuteron beams were delivered by the 5.5 MV Tandem Van de Graaff accelerator of the Institute of Nuclear and Particle Physics at N.C.S.R. “Demokritos”. Additional to the experimental study, calculations were performed using the talys code (v. 1.9). The experimental data of the present work along with the previous measurements were compared with the talys results so as to investigate the reproduction of the experimental data for the different level density models of the code.
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| 4. |
- Spolaore, P., et al.
(author)
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Identification and study of the very neutron deficient nuclide I-111 : search for octupole correlations in the region of N approximate to Z approximate to 56
- 2001
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In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 682, s. 387C-393C
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Journal article (peer-reviewed)abstract
- High-spin states in the neutron-deficient nuclide I-111 have been populated with the fusion reaction Ni-58 + Ni-58 at a beam energy of 210 MeV, in an experiment performed at the Tandem Accelerator of the Laboratori Nazionali di Legnaro. The gamma spectrometer GASP was used in time coincidence with the ISIS Si-ball and the CAMEL recoil mass spectrometer for the positive identification of the nuclide. Gamma transitions and structure details previously attributed to I-111 by Other authors are only partially confirmed. The obtained level scheme includes new rotational bands and a new low lying structure which suggests the presence of octupole correlations at predicted rotational frequency values.
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| 5. |
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| 6. |
- Gadea, A, et al.
(author)
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Hindered E4 decay of the 12(+) yrast trap in Fe-52
- 2005
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 619:1-2, s. 88-94
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Journal article (peer-reviewed)abstract
- The gamma decay of the 12(+) yrast trap in Fe-52 has been measured for the first time. The two E4 gamma-branches to the 8(+) states are hindered with respect to other B(E4) reduced transition probabilities measured in the f(7/2) shell. The interpretation of the data is given in the full pf shell model framework, comparing the results obtained with different residual interactions. It is shown that measurements of hexadecapole transition probabilities constitute a powerful tool in discriminating the correct configuration of the involved wavefunctions.
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| 7. |
- du Rietz, Rickard, et al.
(author)
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Investigation of High-spin States in 53Fe
- 2005
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 72:1
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Journal article (peer-reviewed)abstract
- The fusion-evaporation reactions Si-28(S-32,1 alpha 2p1n)Fe-53 at 125 MeV and Mg-24(S-32,2p1n)Fe-53 at a 95-MeV beam energy were used to investigate excited states in Fe-53. The combination of the Gammasphere Ge detector array and ancillary devices led to the construction of an extensive level scheme comprising some 90 transitions connecting 40 states. The lifetime of the yrast 25/2(-) state and upper limits for the lifetimes of a number of additional states were determined using the Cologne plunger device coupled to the GASP gamma-ray spectrometer. The experimental results are compared to large-scale shell-model calculations using different sets of two-body matrix elements. In particular, predictions on electromagnetic decay properties such as lifetimes, branching ratios, and mixing ratios are studied in detail.
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| 8. |
- Georgali, E., et al.
(author)
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Cross-section measurements of the Dy-156(n, 2n)Dy-155 reaction at neutron energies higher than 17 MeV
- 2021
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 104:6
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Journal article (peer-reviewed)abstract
- In the present work the cross section of the 156Dy (n, 2n) 155Dy reaction (Eth = 9.51 MeV) was measured at neutron beam energies above 17 MeV: 17.1, 18.1, and 19.0 MeV. The irradiations were performed at the 5.5-MV tandem accelerator of the Institute of Nuclear and Particle Physics at N.C.S.R. "Demokritos", where quasimonoenergetic neutron beams were produced via the 3H (d, n) 4He reaction. The cross-section measurements were performed by means of the activation technique relative to the 27Al (n, alpha) 24Na reference reaction. Within the present work the experimental study is framed by theoretical calculations performed via the TALYS code (version 1.95).
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| 9. |
- Kalamara, A., et al.
(author)
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Determination of the Ir-193(n, 2n) reaction cross section and correction methodology for the Ir-191(n, gamma) contamination
- 2019
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In: European Physical Journal A. - : SPRINGER. - 1434-6001 .- 1434-601X. ; 55:10
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Journal article (peer-reviewed)abstract
- The cross section of the Ir-193(n, 2n)Ir-192 reaction has been determined by means of the activation technique, relative to the Al-27(n, alpha) and Au-197(n, 2n) reference reactions cross sections, at neutron beam energies ranging from 10 to 21 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" via the H-2(d, n) and H-3(d, n) reactions. The induced gamma-ray activity of the irradiated target and reference foils was measured with high resolution HPGe detectors. In order to correct for the contribution of the Ir-191(n, gamma)Ir-192 reaction, which is open to low energy parasitic neutrons, a recently developed analysis method was implemented and it is presented in great detail. Furthermore, cross section theoretical calculations were carried out using the EMPIRE and TALYS codes over a wide energy range.
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| 10. |
- Andreoiu, Corina, et al.
(author)
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First Identification of Excited States in 59Zn
- 2002
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 15, s. 459-462
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Journal article (peer-reviewed)abstract
- Excited states in 59Zn were observed for the first time following the fusion-evaporation reaction 24Mg + 40Ca at a beam energy of 60 MeV. The GASP array in conjunction with the ISIS Silicon ball and the NeutronRing allowed for the detection of n-rays in coincidence with evaporated light particles. The mirror symmetry of 59Zn and 59Cu is discussed.
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