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| 2. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 3. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 5. |
- Chatillon, A., et al.
(författare)
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Fission-fragment yields measured in Coulomb-induced fission of U-234,U-235,U-236,U-238 and Np-237,Np-238 with the (RB)-B-3/SOFIA setup
- 2023
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Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284
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Konferensbidrag (refereegranskat)abstract
- Low energy fission of (234,235,236,238)u and Np-237,Np-381 radioactive beams, provided by the GSI/FRS facility, has been studied using the (RB)-B-3/SOFIA setup. The latter allows, on an event-by-event basis, to simultaneously identify, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission. This presentation reports on new results on elemental, isobaric and isotopic yields.
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| 6. |
- Chatillon, A., et al.
(författare)
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Evidence for a New Compact Symmetric Fission Mode in Light Thorium Isotopes
- 2020
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 124:20
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Tidskriftsartikel (refereegranskat)abstract
- Taking benefit of the R3B/SOFIA setup to measure the mass and the nuclear charge of both fission fragments in coincidence with the total prompt-neutron multiplicity, the scission configurations are inferred along the thorium chain, from the asymmetric fission in the heavier isotopes to the symmetric fission in the neutron-deficient thorium. Against all expectations, the symmetric scission in the light thorium isotopes shows a compact configuration, which is in total contrast to what is known in the fission of the heavier thorium isotopes and heavier actinides. This new main symmetric scission mode is characterized by a significant drop in deformation energy of the fission fragments of about 19 MeV, compared to the well-known symmetric scission in the uranium-plutonium region.
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| 7. |
- Chatillon, A., et al.
(författare)
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Influence of proton and neutron deformed shells on the asymmetric fission of thorium isotopes
- 2022
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 106:2
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Tidskriftsartikel (refereegranskat)abstract
- Mean values of the number of protons and neutrons of the primary fission fragments at scission are determined for the asymmetric fission of 16 fissioning isotopes, from Ac-219 up to Np-238. Our results confirm that the main asymmetric fission mode around the heavier uranium isotopes is indeed characterized by an average atomic number around (Z(H)) = 54 in the heavy fission fragments. However, they also unambiguously show a stabilization effect in the light fission fragments around (N-L) = 52-54 in the neutron-deficient thorium and actinium isotopes. This is a clear signature that these deformed proton and neutron shell closures around 54 play a major role in the nuclear fission process. The evolution along the thorium chain shows that the neutron shell appears to be dominant in the asymmetric fission of the lighter thorium isotopes, in contrast to the heavier thorium isotopes for which the stabilization originates from the proton shell.
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| 8. |
- Martin, J. F., et al.
(författare)
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Fission-fragment yields and prompt-neutron multiplicity for Coulomb-induced fission of and
- 2021
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Ingår i: Physical Review C. - 2469-9993 .- 2469-9985. ; 104:4
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Tidskriftsartikel (refereegranskat)abstract
- Low-energy fission of and radioactive beams, provided by the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung facility (GSI), has been studied using the Reactions with Relativistic Radioactive Beams / Studies on Fission with Aladin (R3B/SOFIA) setup. The latter allows us, on an event-by-event basis, to simultaneously identify, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission. This article reports new results on elemental, isotonic, isobaric, and isotopic yields. Moreover, the high accuracy of our data allowed us to study in detail proton even-odd staggering, from elemental yields; neutron excess, from isotopic yields; and total prompt-neutron multiplicity, from the difference of masses of the fissioning nucleus and fission fragments. These results are then compared to previous experimental data in order to probe how these fission observables change as function of the excitation energy and atomic and neutron numbers of the compound nucleus.
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| 10. |
- Tanaka, Y. K., et al.
(författare)
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Search for eta '-mesic nuclei using (p,d) reaction with FRS/Super-FRS at GSI/FAIR
- 2020
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1643
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Tidskriftsartikel (refereegranskat)abstract
- We plan a semi-exclusive measurement of the C-12(p,dp) reaction to search for eta'-mesic nuclei, aiming at investigating in-medium properties of the eta'-meson. We employ a 2.5 GeV proton beam impinging on a carbon target to produce eta'-mesic C-11 nuclei via the C-12(p,d)eta'circle times C-11 reaction. Using coincidence measurements of the forward going deuterons, important for missing-mass spectroscopy, and decay protons emitted from the eta'-mesic nuclei for event selection will provide a high experimental sensitivity to observe eta'-mesic nuclei. We will perform the measurements by combining the WASA detector system with the fragment separator FRS at GSI and also with the Super-FRS at FAIR in the future. The plan of the experiments and the present status are reported.
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| 11. |
- Valiente-Dobón, J.J., et al.
(författare)
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Manifestation of the Berry phase in the atomic nucleus 213Pb
- 2021
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 816
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-rich 213Pb isotope was produced in the fragmentation of a primary 1 GeV A 238U beam, separated in FRS in mass and atomic number, and then implanted for isomer decay γ-ray spectroscopy with the RISING setup at GSI. A newly observed isomer and its measured decay properties indicate that states in 213Pb are characterized by the seniority quantum number that counts the nucleons not in pairs coupled to angular momentum J=0. The conservation of seniority is a consequence of a geometric phase associated with particle-hole conjugation, which becomes observable in semi-magic nuclei where nucleons half-fill the valence shell. The γ-ray spectroscopic observables in 213Pb are thus found to be driven by two mechanisms, particle-hole conjugation and seniority conservation, which are intertwined through a Berry phase.
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| 12. |
- Zago, L., et al.
(författare)
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High-spin states in 212Po above the α-decaying (18+) isomer
- 2022
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 834
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Tidskriftsartikel (refereegranskat)abstract
- The nucleus 212Po has been produced through the fragmentation of a 238U primary beam at 1 GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer γ-decay spectroscopy with the RISING setup. Two delayed previously unknown γ rays have been observed. One has been attributed to the E3 decay of a 21− isomeric state feeding the α-emitting 45-s (18+) high-spin isomer. The other γ-ray line has been assigned to the decay of a higher-lying 23+ metastable state. These are the first observations of high-spin states above the 212Po (18+) isomer, by virtue of the selectivity obtained via ion-by-ion identification of 238U fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high-j proton and neutron orbitals, to which the region around Z∼100 is sensitive.
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| 13. |
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| 14. |
- Bížová, B., et al.
(författare)
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Single-dose cefixime 800 mg plus doxycycline 100 mg b.i.d. for 7 days compared to single-dose ceftriaxone 1 g plus single-dose azithromycin 2 g for treatment of urogenital, rectal and pharyngeal gonorrhoea : A randomised clinical trial
- 2024
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Ingår i: Clinical Microbiology and Infection. - : European Society of Clinical Microbiology and Infectious Diseases (ESCMID). - 1198-743X .- 1469-0691. ; 30:2, s. 211-215
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate the efficacy and tolerability of single-dose oral cefixime 800 mg plus oral doxycycline 100 mg b.i.d. for 7 days, compared to recommended single-dose ceftriaxone plus single-dose, oral azithromycin, for treatment of uncomplicated urogenital, rectal or pharyngeal gonorrhoea.METHODS: A non-inferiority, open-label, multicentre randomised controlled trial was conducted in Prague, Czech Republic. Some 161 patients, 18-65 years of age diagnosed with uncomplicated urogenital, rectal or pharyngeal gonorrhoea by nucleic acid amplification test (NAAT) were randomised to treatment with single-dose cefixime 800 mg plus doxycycline 100 mg b.i.d. for 1 week or single-dose ceftriaxone 1 g intramuscularly plus single-dose azithromycin 2 g. The primary outcome was the number of participants with negative culture and NAAT at 1 week and 3 weeks, respectively, after treatment initiation.RESULTS: In all, 161 patients were randomised, 152 were included in per-protocol analyses. All 76 (100%; 95% confidence interval [CI], 0.95-1.00) patients treated with ceftriaxone plus azithromycin achieved negative cultures and NAAT after treatment. In the cefixime plus doxycycline arm at week 1, culture was negative in all 76 (100%) patients; at week 3, culture was negative in 70/76 patients (92%; 95%CI, 0.84-0.97) and NAAT negative in 66/76 patients (87%; 95%CI, 0.77-0.94). At week 3, culture and NAAT were negative in 65/76 patients (86%; 95%CI, 0.76-0.93). Per-protocol risk difference was 14.5% (95%CI, 6.56-22.38). All treatment failures observed in the cefixime arm were pharyngeal gonorrhoea cases.CONCLUSION: The combination of cefixime and doxycycline did not achieve non-inferiority to ceftriaxone and azithromycin for treatment of gonorrhoea when including pharyngeal gonorrhoea. It did, however, show high efficacy for urogenital and rectal gonorrhoea.
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| 15. |
- Brlík, Vojtěch, et al.
(författare)
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Animal tracing with sulfur isotopes : Spatial segregation and climate variability in Africa likely contribute to population trends of a migratory songbird
- 2023
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 92:7, s. 1320-1331
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Tidskriftsartikel (refereegranskat)abstract
- Climatic conditions affect animals but range-wide impacts at the population level remain largely unknown, especially in migratory species. However, studying climate–population relationships is still challenging in small migrants due to a lack of efficient and cost-effective geographic tracking method. Spatial distribution patterns of environmental stable isotopes (so called ‘isoscapes’) generally overcome these limitations but none of the currently available isoscapes provide a substantial longitudinal gradient in species-rich sub-Saharan Africa. In this region, sulphur (δ34S) has not been sufficiently explored on a larger scale. We developed a δ34S isoscape to trace animal origins in sub-Saharan Africa by coupling known-origin samples from tracked migratory birds with continental remotely sensed environmental data building on environment–δ34S relationships using a flexible machine learning technique. Furthermore, we link population-specific nonbreeding grounds with interannual climatic variation that might translate to breeding population trends. The predicted δ34S isotopic map featured east–west and coast-to-inland isotopic gradients and was applied to predict nonbreeding grounds of three breeding populations of Eurasian Reed Warblers Acrocephalus scirpaceus with two distinct migratory phenotypes. Breeding populations as well as migratory phenotypes exhibited large-scale segregation within the African nonbreeding range. These regions also differed substantially in the interannual climatic variation, with higher interannual variability in the eastern part of the range during 2001–2012. Over the same period, the eastern European breeding population seemed to have experienced a more steep decline in population size. The link between migratory patterns and large-scale climatic variability appears important to better understand population trajectories in many declining migratory animals. We believe animal tracing using sulphur isotopes will facilitate these efforts and offers manifold ecological and forensic applications in the biodiversity hotspot of sub-Saharan Africa.
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