| 1. |
- Siciliano, M., et al.
(author)
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Pairing-quadrupole interplay in the neutron-deficient tin nuclei : First lifetime measurements of low-lying states in Sn-106,Sn-108
- 2020
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In: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 806
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Journal article (peer-reviewed)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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| 2. |
- Davis-Merry, T. R., et al.
(author)
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Collective excitations in the transitional nuclei Re-163 and Re-165
- 2015
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:3
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Journal article (peer-reviewed)abstract
- Excited states in the neutron-deficient nuclei (163)(75) Re-88 and (165)(75) Re-90 were populated in the Cd-106(Ni-60, p2n gamma) and Mo-92(Kr-78, 3p2n gamma) fusion-evaporation reactions at bombarding energies of 270 and 380 MeV, respectively.. rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated in-flight by the RITU gas-filled recoil separator and implanted in the GREAT spectrometer. The energy level schemes for Re-163 and Re-165 were identified using recoil-decay correlation techniques. At low spin, the yrast bands of these isotopes consist of signature partner bands based on a single pi h(11/2) quasiproton configuration. The bands display large energy splitting consistent with the soft triaxial shape typical of transitional nuclei above N = 82. The configurations of the excited states are proposed within the framework of the cranked shell model.
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| 3. |
- Drummond, M. C., et al.
(author)
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Low-lying excited states in the neutron-deficient isotopes Os-163 and Os-165
- 2013
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:5, s. 054309-
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Journal article (peer-reviewed)abstract
- Excited states in the neutron-deficient isotopes Os-163 and Os-165 were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The Os-163 and Os-165 nuclei were populated via the Cd-106(Ni-60,3n) and Mo-92(Kr-78,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the f(7/2) and h(9/2) orbitals.
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| 4. |
- Doncel, Maria, et al.
(author)
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Lifetime measurements of excited states in W-162 and W-164 and the evolution of collectivity in rare-earth nuclei
- 2017
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 95:4
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Journal article (peer-reviewed)abstract
- Lifetimes of the first excited 2(+) states in the extremely neutron- deficient W-162 and W-164 nuclei have been measured using the recoil distance Doppler shift technique. Experimental B(E2) data for the isotopic chains of hafnium, tungsten, and osmium, from the midshell region near the beta-stability line towards the N = 82 closed shell and the most neutron-deficient nuclides, are compared with predictions of nuclear deformations and 2(1)(+) -> 0(g.s)(.+) reduced transition strengths from different classes of state-of-the-art theoretical model calculations. The results reveal striking differences and deficiencies in the predictive power of current nuclear structure models.
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| 5. |
- Grahn, T., et al.
(author)
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Excited states and reduced transition probabilities in Os-168
- 2016
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In: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 94:4
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Journal article (peer-reviewed)abstract
- The level scheme of the neutron-deficient nuclide Os-168 has been extended and mean lifetimes of excited states have been measured by the recoil distance Doppler-shift method using the JUROGAM gamma-ray spectrometer in conjunction with the IKP Koln plunger device. The 168Os. rays were measured in delayed coincidence with recoiling fusion-evaporation residues detected at the focal plane of the RITU gas-filled separator. The ratio of reduced transition probabilities B(E2; 4(1)(+)-> 2(1)(+))/B(E2; 2(1)(+)-> 0(1)(+)) is measured to be 0.34(18), which is very unusual for collective band structures and cannot be reproduced by interacting boson model (IBM-2) calculations based on the SkM* energy-density functional.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Lewis, M. C., et al.
(author)
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Decay of a 19(-) isomeric state in Lu-156
- 2018
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:2
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Journal article (peer-reviewed)abstract
- A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10(+) state in Lu-156 has been discovered. The Lu-156 nuclei were produced by bombarding isotopically enriched Cd-106 targets with beams of Ni-58 ions, separated in flight using the gas-filled separator RITU and their decays were measured using the GREAT spectrometer. Analysis of the main decay path that populates yrast states observed previously suggests a spin-parity assignment of 19(-) for the isomeric state, which is consistent with isomeric states identified in the N = 85 isotones. Comparison with other decay paths in Lu-156 indicates that the [pi h(11/)(2)(-1) circle times nu h(9/2)]10(+) state at the bottom of the yrast sequence is likely to be the a-decaying isomeric state, with the [pi h(11/)(2)(-1) circle times nu f(7/2)]9(+) state lying 62 keV above it. The relative ordering of the lowest-lying 9(+) and 10(+) states is inverted in Lu-156 compared with its odd-odd isotones.
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| 10. |
- Li, Hongjie, et al.
(author)
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First identification of rotational band structures in Re-166(75)91
- 2015
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 92:1
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Journal article (peer-reviewed)abstract
- Excited states in the odd-odd, highly neutron-deficient nucleus Re-166 have been investigated via the Mo-92(Kr-78, 3p1n)Re-166 reaction. Prompt gamma rays were detected by the JUROGAM II. gamma-ray spectrometer, and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and implanted into the Gamma Recoil Electron Alpha Tagging spectrometer located at the RITU focal plane. The tagging and coincidence techniques were applied to identify the gamma-ray transitions in Re-166, revealing two collective, strongly coupled rotational structures, for the first time. The more strongly populated band structure is assigned to the pi h(11/2)[514]9/2(-) circle times vi(13/2)[660]1/2(+) Nilsson configuration, while the weaker structure is assigned to be built on a two-quasiparticle state of mixed pi h(11/2)[514]9/2(-) circle times v[h(9/2)f(7/2)]3/2(-) character. The configuration assignments are based on the electromagnetic characteristics and rotational properties, in comparison with predictions from total Routhian surface and particle-rotor model calculations.
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| 11. |
- Li, Hongjie, et al.
(author)
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Recoil-decay tagging spectroscopy of W-162(74)88
- 2015
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 92:1
-
Journal article (peer-reviewed)abstract
- Excited states in the highly neutron-deficient nucleus W-162 have been investigated via the Mo-92(Kr-78, 2 alpha) W-162 reaction. Prompt gamma rays were detected by the JUROGAM II high-purity germanium detector array and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and identified with the gamma recoil electron alpha tagging (GREAT) spectrometer at the focal plane of RITU. gamma rays from W-162 were identified uniquely using mother-daughter and mother-daughter-granddaughter alpha-decay correlations. The observation of a rotational-like ground-state band is interpreted within the framework of total Routhian surface (TRS) calculations, which suggest an axially symmetric ground-state shape with a gamma-soft minimum at beta(2) approximate to 0.15. Quasiparticle alignment effects are discussed based on cranked shell model calculations. New measurements of the W-162 ground-state alpha-decay energy and half-life were also performed. The observed alpha-decay energy agrees with previous measurements. The half-life of W-162 was determined to be t(1/2) = 990(30) ms. This value deviates significantly from the currently adopted value of t(1/2) = 1360(70) ms. In addition, the alpha-decay energy and half-life of Os-166 were measured and found to agree with the adopted values.
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| 12. |
- Saygi, B., et al.
(author)
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Reduced transition probabilities along the yrast line in W-166
- 2017
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 96:2
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Journal article (peer-reviewed)abstract
- Lifetimes of excited states in the yrast band of the neutron-deficient nuclide W-166 have been measured utilizing the DPUNS plunger device at the target position of the JUROGAM II gamma-ray spectrometer in conjunction with the RITU gas-filled separator and the GREAT focal-plane spectrometer. Excited states in W-166 were populated in the Mo-92(Kr-78, 4p) reaction at a bombarding energy of 380 MeV. The measurements reveal a low value for the ratio of reduced transitions probabilities for the lowest-lying transitions B(E2; 4(+)-> 2(+)) / B(E2; 2(+)-> 0(+)) = 0.33(5), compared with the expected ratio for an axially deformed rotor (B-4/2 = 1.43).
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| 13. |
- Siciliano, M., et al.
(author)
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Lifetime measurements in the even-even 102-108Cd isotopes
- 2021
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 104:3
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Journal article (peer-reviewed)abstract
- Background: The heaviest T-z = 0 doubly-magic nucleus, Sn-100, and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structure of light-Sn nuclei has been shown to be affected by the delicate balance between nuclear-interaction components, such as pairing and quadrupole correlations. From Cd to Te, many common features and phenomena have been observed experimentally along the isotopic chains, leading to theoretical studies devoted to a more general and comprehensive study of the region. In this context, having only two proton holes in the Z = 50 shell, the Cd isotopes are expected to present properties similar to those found in the Sn isotopic chain.Purpose: The aim of this work was to measure lifetimes of excited states in neutron-deficient nuclei in the vicinity of Sn-100.Methods: The neutron-deficient nuclei in the N approximate to Z approximate to 50 region were populated using a multinucleon transfer reaction with a Cd-106 beam and a Mo-92 target. The beamlike products were identified by the VAMOS++ spectrometer, while the gamma rays were detected using the AGATA array. Lifetimes of excited states were determined using the recoil distance Doppler-shift method, employing the Cologne differential plunger.Results: Lifetimes of low-lying states were measured in the even-mass Cd-102-(108) isotopes. In particular, multiple states with excitation energy up to MeV, belonging to various bands, were populated in approximate to 3 Cd-106 via inelastic scattering. The transition strengths corresponding to the measured lifetimes were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach.Conclusions: Despite the similarities in the electromagnetic properties of the low-lying states, there is a fundamental structural difference between the ground-state bands in the Z = 48 and Z = 50 isotopes. The comparison between experimental and theoretical results revealed a rotational character of the Cd nuclei, which have prolate-deformed ground states with beta(2) approximate to 0.2. At this deformation Z = 48 becomes a closed-shell configuration, which is favored with respect to the spherical one.
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| 14. |
- Siciliano, M., et al.
(author)
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STUDY OF QUADRUPOLE CORRELATIONS IN N = Z=5 0 REGION VIA LIFETIME MEASUREMENTS
- 2017
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In: Acta Physica Polonica B. - : Jagiellonian University Press. - 0587-4254 .- 1509-5770. ; 48:3, s. 331-336
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Journal article (peer-reviewed)abstract
- During the AGATA campaign at GANIL, the neutron-deficient Sn region was populated via a multi-nucleon transfer reaction in order to directly measure the lifetime of the first excited states with a plunger device, providing complementary information to previous results obtained with Coulomb excitation experiments. The AGATA gamma-ray array was used together with the VAMOS++ spectrometer to study the nuclei of interest.
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| 15. |
- Testov, D. A., et al.
(author)
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Octupole correlations near Te 110
- 2021
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In: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 103:4
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Journal article (peer-reviewed)abstract
- The lifetime of the 2+ and 9-, 11-, 13-, 15- states in the neutron-deficient Te110 was measured for the first time using the recoil distance Doppler shift technique. The reported value of the reduced transition probability B(E2;0g.s+→2+)=4.3(8)×103e2fm4 supports the systematic for even-mass Te isotopes and was interpreted in the framework of the large-scale shell model and cranked shell model calculations. The measured reduced transition probabilities in the negative-parity yrast band revealed the upward trend towards the high spins. The enhanced collectivity is discussed in terms of the tilted axis cranking approach and the symmetry configuration mixing method with the Gogny D1S interaction.
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| 16. |
- Testov, D., et al.
(author)
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High Resolution γ-Ray Spectrometry Using Galileo Array
- 2019
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In: Eurasian Journal of Physics and Functional Materials. - : L.N. Gumilyov Eurasian National University. - 2522-9869. ; 3:1, s. 84-90
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Journal article (peer-reviewed)abstract
- The GALILEO γ-ray spectrometer has been constructed at the Legnaro National Laboratory of INFN (LNL-INFN). It can be coupled to advanced ancillary devices which allows nuclear structure studies employing the variety of in-beam γ-ray spectroscopy methods. Such studies benefit from reactions induced by the intense stable beams delivered by the Tandem-ALPI-PIAVE accelerator complex and by the radioactive beams which will be provided by the SPES facility. In this paper we outline two experiments performed within the experimental campaign at GALILEO coupled to the EUCLIDES Si-ball and the Neutron Wall array. The first one was aimed at spectroscopic studies in A=31 mirror nuclei and the second one at measurements of lifetimes of excited states in nuclei in the vicinity of 100Sn.
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| 17. |
- Valiente-Dobon, J. J., et al.
(author)
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NEDA-NEutron Detector Array
- 2019
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 927, s. 81-86
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Journal article (peer-reviewed)abstract
- The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.
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