| 1. |
- Fernández, A., et al.
(författare)
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Reinterpretation of excited states in 212Po: Shell-model multiplets rather than α-cluster states
- 2021
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 104:5
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Tidskriftsartikel (refereegranskat)abstract
- A γ-ray spectroscopic study of 212Po was performed at the Grand Accélérateur National d'Ions Lourds, using the inverse kinematics α-transfer reaction 12C(208Pb,212Po)8Be and the AGATA spectrometer. A careful analysis based on γγ coincidence relations allowed us to establish 14 new excited states in the energy range between 1.9 and 3.3 MeV. None of these states, however, can be considered as candidates for the levels with spins and parities of 1− and 2− and excitation energies below 2.1 MeV, which have been predicted by recent α-cluster model calculations. A systematic comparison of the experimentally established excitation scheme of 212Po with shell-model calculations was performed. This comparison suggests that the six states with excitation energies (spins and parities) of 1744 (4−), 1751 (8−), 1787 (6−), 1946 (4−), 1986 (8−), and 2016 (6−) keV, which previously were interpreted as α-cluster states, may in fact be of positive parity and belong to low-lying shell-model multiplets. This reinterpretation of the structure of 212Po is supported by experimental information with respect to the linear polarization of γ rays, which suggests a magnetic character of the 432-keV γ ray decaying from the state at an excitation energy of 1787 keV to the 6+ yrast state, and exclusive reaction cross sections.
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| 2. |
- Perez-Vidal, R. M., et al.
(författare)
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Evidence of Partial Seniority Conservation in the pi g9/2 Shell for the N=50 Isotones
- 2022
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 129:11
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Tidskriftsartikel (refereegranskat)abstract
- The reduced transition probabilities for the 4+1 -2+1 and 2+1 -0+1 transitions in 92Mo and 94Ru and for the 4+1 -2+1 and 6+1 -4+1 transitions in 90Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f5=2, p3=2, p1=2, and g9=2 proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N = 50 g9=2 orbital to be understood. The conclusion is that seniority is largely conserved in the first 71g9=2 orbital.
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| 3. |
- Korten, W., et al.
(författare)
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Physics opportunities with the Advanced Gamma Tracking Array : AGATA
- 2020
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 56:5
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Forskningsöversikt (refereegranskat)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.
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| 4. |
- Pasqualato, G., et al.
(författare)
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Shape evolution in even-mass 98-104Zr isotopes via lifetime measurements using the γ γ-coincidence technique
- 2023
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Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 59:11
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Tidskriftsartikel (refereegranskat)abstract
- The Zirconium (Z = 40) isotopic chain has attracted interest for more than four decades. The abrupt lowering of the energy of the first 2(+) state and the increase in the transition strength B(E2; 2(1)(+) -> 0(1)(+) ) going from Zr-98 to Zr-100 has been the first example of "quantum phase transition" in nuclear shapes, which has few equivalents in the nuclear chart. Although a multitude of experiments have been performed to measure nuclear properties related to nuclear shapes and collectivity in the region, none of the measured lifetimes were obtained using the Recoil Distance Doppler Shift method in the gamma gamma-coincidence mode where a gate on the direct feeding transition of the state of interest allows a strict control of systematical errors. This work reports the results of lifetime measurements for the first yrast excited states in Zr98-104 carried out to extract reduced transition probabilities. The new lifetime values in gamma gamma-coincidence and gamma-single mode are compared with the results of former experiments. Recent predictions of the Interacting Boson Model with Configuration Mixing, the Symmetry Conserving Configuration Mixing model based on the Hartree-Fock- Bogoliubov approach and the Monte Carlo Shell Model are presented and compared with the experimental data.
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| 5. |
- Andreyev, A. N., et al.
(författare)
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α decay of the neutron-deficient isotope 190At
- 2023
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Ingår i: Physical Review C. - 2469-9985. ; 108:3
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Tidskriftsartikel (refereegranskat)abstract
- The α decay of the neutron-deficient 190At isotope was observed following the 103Rh(90Zr,3n)190At reaction at Argonne National Laboratory. The reaction products were separated from the beam using the Argonne Gas-Filled Analyzer and implanted into a double-sided Si strip detector. The spatial and temporal correlations between implanted nuclei and subsequent α decays towards the known daughter isotope 186Bi were used to identify and characterize 190At nuclei. Two possible decay scenarios are proposed for the 190At→186Bi decay.
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| 6. |
- Basu, Anwesha, et al.
(författare)
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Highly deformed band structures due to core excitations in Xe 123
- 2021
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Ingår i: Physical Review C. - 2469-9985. ; 103:1
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Xe123 were populated in the Se80(Ca48, 5n)Xe123 reaction at a beam energy of 207 MeV. γ-ray coincidence events were recorded with the Gammasphere spectrometer. Four new high-spin bands have been discovered in this nucleus. The bands are compared with those calculated within the framework of cranked Nilsson-Strutinsky and cranked Nilsson-Strutinsky-Bogoliubov models. It is concluded that the configurations of the bands involve two-proton excitations across the Z=50 as well as excitation of neutrons across the N=82 shell gaps resulting in a large deformation, 2≈0.30 and γ≈5°C.
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| 7. |
- Basu, Anwesha, et al.
(författare)
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Evolution of collective and noncollective structures in Xe 123
- 2020
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Ingår i: Physical Review C. - 2469-9985. ; 101:2
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Tidskriftsartikel (refereegranskat)abstract
- An experiment involving a heavy-ion-induced fusion-evaporation reaction was carried out where high-spin states of Xe123 were populated in the Se80(Ca48,5n)Xe123 reaction at 207 MeV beam energy. Gamma-ray coincidence events were recorded with the Gammasphere Ge detector array. The previously known level scheme was confirmed and enhanced with the addition of five new band structures and several interband transitions. Cranked Nilsson-Strutinsky (CNS) calculations were performed and compared with the experimental results in order to assign configurations to the bands.
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| 8. |
- Ljungvall, J., et al.
(författare)
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Performance of the Advanced GAmma Tracking Array at GANIL
- 2020
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 955
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Tidskriftsartikel (refereegranskat)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 γ-ray tracking are discussed. Recent developments of γ-ray tracking are also presented. The experimentally achieved peak-to-total is compared with simulations showing the impact of back-scattered γ rays on the peak-to-total in a γ-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 γ-ray tracking on the normalization of the angular correlations.
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| 9. |
- de Angelis, G., et al.
(författare)
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AGATA : nuclear structure advancements with fusion-evaporation reactions
- 2023
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 59:7
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear-structure studies using fusion reactions are reviewed in terms of prospects for advancement using the next generation of ?-ray tracking arrays such as AGATA. Properties discussed include those of light N = Z nuclei and rotational behaviour in heavy nuclei at high values of angular momentum and internal excitation energy.
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| 10. |
- Bemmoussat, A., et al.
(författare)
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Contribution of Satellite-Based Precipitation in Hydrological Rainfall–Runoff Modeling : Case Study of the Hammam Boughrara Region in Algeria
- 2021
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Ingår i: Earth Systems and Environment. - : Springer Nature. - 2509-9426 .- 2509-9434. ; 5:4, s. 873-881
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Tidskriftsartikel (refereegranskat)abstract
- Hydrological models are viewed as powerful tools that have a major importance for managing water resources and predicting flows. It should be specified that the meteorological parameter rainfall is the main input in these models. In the current study, data from only one rainfall station are available over the analysis domain, which cannot represent the entire Hammam Boughrara watershed of Algeria. The precipitation data remotely detected by the tropical rainfall measuring mission (TRMM) provide good spatial coverage in the watershed and can be used to fill in the missing data. The use of raw TRMM data gives poor results from the simulated flow rates with a Nash–Sutcliffe efficiency NSE equal to 0.34 for the validation period that ranges from year 2000 to 2005; this is mainly due to uncertainties in the TRMM data. For this reason, it was deemed necessary to carry out a performance test of the model. The results obtained give an unsatisfactory percent bias (PBIAS) of − 46.24%, which suggests the need to perform a correction to decrease the PBIAS of satellite precipitation. For this, two methods were used: the linear regression method and the multiplicative method. These two techniques can only be applied if there is at least one rainfall measurement station available in the watershed. The obtained results are very satisfactory since the PBIAS reaches − 0.62% for the linear regression method and − 11.58% for the multiplicative method. In addition, the use of corrected TRMMs gives also very good results with a Nash–Sutcliffe efficiency that ranges from 0.74 to 0.88 for both validation and calibration periods. Overall, the current study is supportive to estimate the satellite-based rainfall, one of the very sensitive to measure the meteorological parameter, in northwestern Algeria.
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