| 1. |
- Das, B., et al.
(författare)
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Nature of seniority symmetry breaking in the semimagic nucleus Ru-94
- 2022
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Ingår i: Physical Review C. - : AMER PHYSICAL SOC. - 2469-9985 .- 2469-9993. ; 105:3
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Tidskriftsartikel (refereegranskat)abstract
- Direct lifetime measurements via gamma -gamma coincidences using a fast timing detector array consisting of LaBr3(Ce) scintillators has been applied to determine the lifetime of low-lying states in the semimagic (N = 50) nucleus Ru-94. The experiment was carried out as the first in a series of "FAIR-0" experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in Ru-94 were populated primarily via the beta-delayed proton emission of Pd-95 nuclei, produced in the projectile fragmentation of an 850 MeV/nucleon Xe-124 beam impinging on a 4 g/cm(2) Be-9 target. While the deduced E2 strength for the 2(+) -> 0(+) transition in the yrast cascade follows the expected behavior for conserved seniority symmetry, the intermediate 4(+) -> 2(+) transition exhibits a drastic enhancement of transition strength in comparison with pure-seniority model predictions as well as standard shell model predictions in the f pg proton hole space with respect to doubly magic Sn-100. The anomalous behavior is ascribed to a subtle interference between the wave function of the lowest seniority v = 2, I-pi = 4(+) state and that of a close-lying v = 4 state that exhibits partial dynamic symmetry. In addition, the observed strongly prohibitive 6(+) -> 4(+) transition can be attributed to the same mechanism but with a destructive interference. It is noted that such effects may provide stringent tests of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations.
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| 2. |
- Kukkonen, J., et al.
(författare)
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Towards a Comprehensive Evaluation of the Environmental and Health Impacts of Shipping Emissions
- 2022
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Ingår i: Springer Proceedings in Complexity. - Cham : Springer International Publishing. - 2213-8684 .- 2213-8692. ; , s. 329-336
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Konferensbidrag (refereegranskat)abstract
- We present a new concept for marine research, applied in the EU-funded project EMERGE, “Evaluation, control and Mitigation of the EnviRonmental impacts of shippinG Emissions” (2020–2024; https://emerge-h2020.eu/ ). For the first time, both the various marine and atmospheric impacts of the shipping sector have been and will be comprehensively analyzed, using a concerted modelling and measurements framework. The experimental part of the project focuses on five European geographical case studies in different ecologically vulnerable regions, and a mobile onboard case study. The EMERGE consortium has also developed a harmonised and integrated modelling framework to assess the combined impacts of shipping emissions, both (i) on the marine ecosystems and (ii) the atmospheric environment. The first results include substantial refinements of a range of models to be applied, especially those for the STEAM and OpenDrift models. In particular, the STEAM (Ship Traffic Emission Assessment Model) model has been extended to allow for the effects of atmospheric and oceanographic factors on the fuel consumption and emissions of the ships. The OpenDrift model has been improved to take into account the partitioning, degradation, and volatilization of pollutants in water. The predicted emission and discharge values have been used as input for both regional scale atmospheric dispersion models, such as WRF-CMAQ (Weather Research and Forecasting—Community Multiscale Air Quality Model) and SILAM (System for Integrated modeLling of Atmospheric composition), and water quality and circulation models, such as OpenDrift (Open source model for the drifting of substances in the ocean) and Delft3D (oceanographic model). The case study regions are Eastern Mediterranean, Northern Adriatic Sea, the Lagoon of Aveiro, the Solent Strait and the Öresund Strait. We have also conducted a substantial part of the experimental campaigns scheduled in the project. The final assessment will include the benefits and costs of control and mitigation options affecting water quality, air pollution exposure, health impacts, climate forcing, and ecotoxicological effects and bioaccumulation of pollutants in marine biota.
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| 3. |
- Petrovic, Jana, 1992-, et al.
(författare)
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Performance Evaluation of an Imaging Radiation Portal Monitor System
- 2022
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:18
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Tidskriftsartikel (refereegranskat)abstract
- An organic scintillator-based radiation portal monitor (RPM) prototype system with imaging capabilities has been developed based on the neutron-gamma emission tomography technique. The technique enables rapid detection and precise location of small amounts of special nuclear materials, such as plutonium, using time and energy correlations between fast neutrons and gamma rays from spontaneous fission with low false-alarm rates. These capabilities, in addition to state-of-the-art detection of various gamma-emitting sources, enables the novel imaging RPM concept to efficiently address global security threats from terrorism and the proliferation of nuclear weapons. The detector approach is simple and versatile and can easily be adapted for different applications in nuclear security, public safety, nuclear emergency response, and radiological surveying. In this work, basic performance parameters of the imaging RPM prototype system developed at KTH have been evaluated.
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| 4. |
- Petrovic, Jana, et al.
(författare)
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Rapid imaging of special nuclear materials for nuclear nonproliferation and terrorism prevention
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:21
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a neutron-gamma emission tomography (NGET) technique for rapid detection, three-dimensional imaging, and characterization of special nuclear materials like weapons-grade plutonium and uranium. The technique is adapted from fundamental nuclear physics research and represents a previously unexplored approach to the detection and imaging of small quantities of these materials. The method is demonstrated on a radiation portal monitor prototype system based on fast organic scintillators, measuring the characteristic fast time and energy correlations between particles emitted in nuclear fission processes. The use of these correlations in real time in conjunction with modern machine learning techniques provides unprecedented imaging efficiency and high spatial resolution. This imaging modality addresses global security threats from terrorism and the proliferation of nuclear weapons. It also provides enhanced capabilities for addressing different nuclear accident scenarios and for environmental radiological surveying.
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| 5. |
- Polettini, M., et al.
(författare)
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Decay studies in the A∼225 Po-Fr region from the DESPEC campaign at GSI in 2021
- 2022
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Ingår i: Il Nuovo Cimento. - : Società Italiana di Fisica. - 2037-4909. ; 45:5
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Tidskriftsartikel (refereegranskat)abstract
- The HISPEC-DESPEC collaboration aims at investigating the structure of exotic nuclei formed in fragmentation reactions with decay spectroscopy measurements, as part of the FAIR Phase-0 campaign at GSI. This paper reports on first results of an experiment performed in spring 2021, with a focus on beta-decaystudies in the Po-Fr nuclei in the 220 < A <230 island of octupole deformation exploiting the DESPEC setup. Ion-beta correlations and fast-timing techniques are being employed, giving an insight into this difficult-to-reach region.
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| 6. |
- Polettini, M., et al.
(författare)
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DESPEC Phase-0 campaign at GSI
- 2021
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Ingår i: NUOVO CIMENTO C-COLLOQUIA AND COMMUNICATIONS IN PHYSICS. - : SOC ITALIANA FISICA. - 2037-4909. ; 44:2-3
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports preliminary results of the DESPEC campaign at GSI, focused on the study of neutron-deficient nuclei approaching Sn-100. The results presented show the isomeric decays of excited states with I-pi = 14(+) and 8(+) in Pd-96 and Pd-94, respectively. The detailed characterisation of the DESPEC set-up and analysis methodologies, proven in this experimental run, are crucial for the future campaigns.
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