| 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. |
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| 3. |
- 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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| 4. |
- Guo, S., et al.
(author)
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Evidence for pseudospin-chiral quartet bands in the presence of octupole correlations
- 2020
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In: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 807
-
Journal article (peer-reviewed)abstract
- Three nearly degenerate pairs of doublet bands are identified in Ba-131. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners pi(d(5/2), g(7/2)) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in Ba-131 have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in Ba-131 are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry.
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| 5. |
- Siciliano, M., et al.
(author)
-
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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- Čolović, P., et al.
(author)
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Population of lead isotopes in binary reactions using a Rb 94 radioactive beam
- 2020
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In: Physical Review C. - 2469-9985. ; 102:5
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Journal article (peer-reviewed)abstract
- We measured absolute cross sections for neutron transfer channels populated in the Rb94+Pb208 binary reaction. Cross sections have been extracted identifying directly the lead isotopes with the high efficiency MINIBALL γ-ray array coupled to a particle detector combined with a radioactive Rb94 beam delivered at Elab=6.2 MeV/nucleon by the HIE-ISOLDE facility. We observed sizable cross sections in the neutron-rich mass region, where the heavy partner acquires neutrons. A fair agreement between the measured cross sections with those from GRAZING calculations gives confidence in the cross-section predictions of more neutron-rich nuclei produced via a larger number of transferred nucleons.
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| 10. |
- Söderström, Pär-Anders, 1980-, et al.
(author)
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Neutron detection and gamma-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537
- 2019
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In: Nuclear Instruments and Methods in Physics Research Section A. - : ELSEVIER SCIENCE BV. - 0168-9002 .- 1872-9576. ; 916, s. 238-245
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Journal article (peer-reviewed)abstract
- In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and gamma rays. Special emphasis is put on the application of artificial neural networks. The results show a systematically higher gamma-ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of gamma rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neutrons could be identified in BC-501A using artificial neural networks down to a recoil proton energy of 800 keV compared to a recoil deuteron energy of 1200 keV for BC-537. We conclude that using artificial neural networks it is possible to obtain the same gamma-ray rejection quality from both BC-501A and BC-537 for neutrons above a low-energy threshold. This threshold is, however, lower for BC-501A, which is important for nuclear structure spectroscopy experiments of rare reaction channels where low-energy interactions dominates.
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