| 1. |
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| 2. |
- Keller, P. S., et al.
(författare)
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Global CO2 emissions from dry inland waters share common drivers across ecosystems
- 2020
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global survey covering 196 dry inland waters across diverse ecosystem types and climate zones. We show that their CO2 emissions share fundamental drivers and constitute a substantial fraction of the carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and climate zones, with local characteristics explaining much of the variability. Accounting for such emissions increases global estimates of carbon emissions from inland waters by 6% (~0.12 Pg C y−1). Our results indicate that emissions from dry inland waters represent a significant and likely increasing component of the inland waters carbon cycle.
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| 3. |
- Ponnath, L., et al.
(författare)
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Measurement of nuclear interaction cross sections towards neutron-skin thickness determination
- 2024
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 855
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Tidskriftsartikel (refereegranskat)abstract
- The accuracy of reaction theories used to extract properties of exotic nuclei from scattering experiments is often unknown or not quantified, but of utmost importance when, e.g., constraining the equation of state of asymmetric nuclear matter from observables as the neutron-skin thickness. In order to test the Glauber multiple-scattering model, the total interaction cross section of [Formula presented] on carbon targets was measured at initial beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The measurements were performed during the first experiment of the newly constructed R3B (Reaction with Relativistic Radioactive Beams) experiment after the start of FAIR Phase-0 at the GSI/FAIR facility with beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The combination of the large-acceptance dipole magnet GLAD and a newly designed and highly efficient Time-of-Flight detector enabled a precise transmission measurement with several target thicknesses for each initial beam energy with an experimental uncertainty of ±0.4%. A comparison with the Glauber model revealed a discrepancy of around 3.1% at higher beam energies, which will serve as a crucial baseline for the model-dependent uncertainty in future fragmentation experiments.
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| 4. |
- Saito, T. R., et al.
(författare)
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Studies of three-and four-body hypernuclei with heavy-ion beams, nuclear emulsions and machine learning
- 2023
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 2586
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Tidskriftsartikel (refereegranskat)abstract
- Interests on few-body hypernuclei have been increased by recent results of experiments employing relativistic heavy ion beams. Some of the experiments have revealed that the lifetime of the lightest hypernucleus, hypertriton, is significantly shorter than 263 ps which is expected by considering the hypertriton to be a weakly-bound system. The STAR collaboration has also measured the hypertriton binding energy, and the deduced value is contradicting to its formerly known small binding energy. These measurements have indicated that the fundamental physics quantities of the hypertriton such as its lifetime and binding energy have not been understood, therefore, they have to be measured very precisely. Furthermore, an unprecedented Lambda nn bound state observed by the HypHI collaboration has to be studied in order to draw a conclusion whether or not such a bound state exists. These three-body hypernuclear states are studied by the heavy-ion beam data in the WASA-FRS experiment and by analysing J-PARC E07 nuclear emulsion data with machine learning.
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| 5. |
- Saito, T. R., et al.
(författare)
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The WASA-FRS project at GSI and its perspective
- 2023
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 542, s. 22-25
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique to study bound states of exotic hadrons in subatomic nuclei, such as hypernuclei and mesic nuclei, has been developed by employing the Fragment Separator FRS and the WASA central detector at GSI. Two experiments, S447 for studying light hypernuclei, especially hypertriton and a Ann bound state, and S490 for searching for ri' mesic-nuclei, were recently performed. Data analyses are currently in progress, and light charged particles such as protons and x & PLUSMN; are clearly observed and identified in the both experiments. For S447, light nuclear fragments that can also be residual nuclei from decays of hypernuclei of interests have been analysed by the FRS, and a momentum resolution, Ap/p, of 5 x 10-4 has been achieved. Further data analyses are to be completed. The WASA-FRS project will be continued and extended with the FRS at FAIR Phase 0, and upgrading of the WASA magnet and detectors is currently in progress. Furthermore, construction of a larger detector system with the Super-FRS at FAIR Phase 1 is also under consideration.
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| 6. |
- Sekiya, R., et al.
(författare)
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Search for η'-mesic nuclei in 12C(p, dp) reaction with the WASA detector at GSI-FRS
- 2024
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Ingår i: Nuovo cimento della societa italiana de fisica. C, Geophysics and space physics. - : Società Italiana di Fisica. - 1124-1896 .- 1826-9885. ; 47:4
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Tidskriftsartikel (refereegranskat)abstract
- We conducted an experimental search for η′-mesic nuclei, bound systems of an η′ meson and a nucleus, in 12C(p, dp) reactions. We measured the missing mass in the (p, d) reaction to obtain the mass spectrum of the reaction product near the η′ emission threshold. Forward-emitted deuterons were momentum-analyzed in the FRS of GSI. We installed a nearly 4π detector WASA near the 12C target to effectively select formation and decay of the η′-mesic nuclei. We are presently finalizing the analysis.
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| 7. |
- Tanaka, Y. K., et al.
(författare)
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WASA-FRS EXPERIMENTS IN FAIR PHASE-0 AT GSI
- 2023
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Ingår i: ACTA PHYSICA POLONICA B PROCEEDINGS SUPPLEMENT. - : Jagiellonian University.
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Konferensbidrag (refereegranskat)abstract
- We have developed a new and unique experimental setup integrating the central part of the Wide Angle Shower Apparatus (WASA) into the Fragment Separator (FRS) at GSI. This combination opens up possibilities of new experiments with high-resolution spectroscopy at forward 0 and measurements of light decay particles with nearly full solid-angle acceptance in coincidence. The first series of the WASA-FRS experiments have been successfully carried out in 2022. The developed experimental setup and two physics experiments performed in 2022 including the status of the preliminary data analysis are introduced.
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| 8. |
- Heil, M., et al.
(författare)
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A new Time-of-flight detector for the R 3 B setup
- 2022
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 58:12
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Tidskriftsartikel (refereegranskat)abstract
- We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R3B experimental setup at GSI and FAIR, Darmstadt, Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision σΔE/ ΔE of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.
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| 9. |
- Kudaibergenova, E., et al.
(författare)
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MEASUREMENTS OF THE REACTION CROSS SECTIONS OF NEUTRON-RICH Sn ISOTOPES AT THE R 3 B SETUP
- 2024
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Ingår i: Acta Physica Polonica B, Proceedings Supplement. - 1899-2358. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- A fundamental framework to describe nuclear matter as a function of pressure and nuclear isospin asymmetry is the nuclear Equation of State (EoS). Constraining the parameters of the EoS is one of the central issues in nuclear physics, especially since the slope parameter L has not yet been constrained well experimentally. It has been identified that a precise determination of the neutron-removal cross section in neutron-rich nuclei, which correlates with the neutron-skin thickness, would provide a more precise constraint on L. To this end, an experiment was performed at the R3B setup in the GSI Helmholtzzentrum für Schwerionenforschung GmbH as a part of the FAIR Phase-0 program. The reactions are studied in inverse kinematics with neutron-rich tin isotopes in the mass range of A = 124–134 on carbon targets of different thicknesses. The reaction products have been measured at beam energies of 400–900 MeV/u in a kinematically complete manner. In this communication, the analysis of124Sn+12C at 900 MeV/u is presented. The charge-exchange reactions, resulting processes, and their role in the calculation of other reaction cross sections are discussed.
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| 10. |
- Lihtar, I., et al.
(författare)
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RELATIVISTIC COULOMB EXCITATION OF 124 Sn
- 2024
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Ingår i: Acta Physica Polonica B, Proceedings Supplement. - 1899-2358. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- The Coulomb excitation of 124, 128, 130, 132, 134Sn isotopes in the electric field of a Pb target have been studied using the R3B setup as a part of the FAIR Phase-0 program. The experiment was motivated by the possibility of using the nuclear dipole response to infer valuable information on the slope of the symmetry energy of the nuclear equation of state. Measurements were performed in inverse kinematics at relativistic energies of 750 MeV/u and 904 MeV/u. The analysis method and preliminary results for the decay channel with a single outgoing neutron for 124Sn are reported.
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| 11. |
- Bott, Lukas Thomas, et al.
(författare)
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Coulomb dissociation of O-16 into He-4 and C-12
- 2023
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Ingår i: NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022. - : EDP Sciences. - 2100-014X. ; 279
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Konferensbidrag (refereegranskat)abstract
- We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4.
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| 12. |
- Cabanelas, P., et al.
(författare)
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Commissioning of the CALIFA Barrel Calorimeter of the R 3 B Experiment at FAIR
- 2020
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1667:1
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Konferensbidrag (refereegranskat)abstract
- CALIFA is the high efficiency and energy resolution calorimeter for the R3B experiment at FAIR, intended for detecting high energy charged particles and γ-rays in inverse kinematics direct reactions. It surrounds the reaction target in a segmented configuration of Barrel and Forward End-Cap pieces. The CALIFA Barrel consists of 1952 detection units made of CsI(Tl) long-shaped scintillator crystals, and it is being commissioned during the Phase0 experiments at FAIR. The first setup for the CALIFA Barrel commissioning is presented here. Results of detector performance with γ-rays are obtained, and show that the system fulfills the design requirements.
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| 13. |
- Cabanelas, P., et al.
(författare)
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Performance recovery of long CsI(Tl) scintillator crystals with APD-based readout
- 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. ; 965
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Tidskriftsartikel (refereegranskat)abstract
- CALIFA is the high efficiency and energy resolution calorimeter for the R3B experiment at FAIR, intended for detecting high energy light charged particles and gamma rays in scattering experiments, and is being commissioned during the Phase-0 experiments at FAIR, between 2018 and 2020. It surrounds the reaction target in a segmented configuration with 2432 detection units made of long CsI(Tl) finger-shaped scintillator crystals. CALIFA has a 10 year intended operational lifetime as the R3B calorimeter, necessitating measures to be taken to ensure enduring performance. In this paper we present a systematic study of two groups of 6 different detection units of the CALIFA detector after more than four years of operation. The energy resolution and light output yield are evaluated under different conditions. Tests cover the aging of the first detector units assembled and investigates recovery procedures for degraded detection units. A possible reason for the observed degradation is given, pointing to the crystal-APD coupling.
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| 14. |
- Feijoo, C., et al.
(författare)
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Harnessing artificial intelligence (AI) to increase wellbeing for all: The case for a new technology diplomacy
- 2020
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Ingår i: Telecommunications Policy. - : Elsevier BV. - 0308-5961. ; 44:6
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Tidskriftsartikel (refereegranskat)abstract
- The field of artificial intelligence (AI) is experiencing a period of intense progress due to the consolidation of several key technological enablers. AI is already deployed widely and has a high impact on work and daily life activities. The continuation of this process will likely contribute to deep economic and social changes. To realise the tremendous benefits of AI while mitigating undesirable effects will require enlightened responses by many stakeholders. Varying national institutional, economic, political, and cultural conditions will influence how AI will affect convenience, efficiency, personalisation, privacy protection, and surveillance of citizens. Many expect that the winners of the AI development race will dominate the coming decades economically and geopolitically, potentially exacerbating tensions between countries. Moreover, nations are under pressure to protect their citizens and their interests—and even their own political stability—in the face of possible malicious or biased uses of AI. On the one hand, these different stressors and emphases in AI development and deployment among nations risk a fragmentation between world regions that threatens technology evolution and collaboration. On the other hand, some level of differentiation will likely enrich the global AI ecosystem in ways that stimulate innovation and introduce competitive checks and balances through the decentralisation of AI development. International cooperation, typically orchestrated by intergovernmental and non-governmental organisations, private sector initiatives, and by academic researchers, has improved common welfare and avoided undesirable outcomes in other technology areas. Because AI will most likely have more fundamental effects on our lives than other recent technologies, stronger forms of cooperation that address broader policy and governance challenges in addition to regulatory and technological issues may be needed. At a time of great challenges among nations, international policy coordination remains a necessary instrument to tackle the ethical, cultural, economic, and political repercussions of AI. We propose to advance the emerging concept of technology diplomacy to facilitate the global alignment of AI policy and governance and create a vibrant AI innovation system. We argue that the prevention of malicious uses of AI and the enhancement of human welfare create strong common interests across jurisdictions that require sustained efforts to develop better, mutually beneficial approaches. We hope that new technology diplomacy will facilitate the dialogues necessary to help all interested parties develop a shared understanding and coordinate efforts to utilise AI for the benefit of humanity, a task whose difficulty should not be underestimated.
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| 15. |
- Feijoo, Pedro C., et al.
(författare)
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Does carrier velocity saturation help to enhance fmax in graphene field-effect transistors?
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:9, s. 4179-4186
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Tidskriftsartikel (refereegranskat)abstract
- It has been argued that current saturation in graphene field-effect transistors (GFETs) is needed to get optimal maximum oscillation frequency (f(max)). This paper investigates whether velocity saturation can help to get better current saturation and if that correlates with enhancedf(max). We have fabricated 500 nm GFETs with high extrinsicf(max)(37 GHz), and later simulated with a drift-diffusion model augmented with the relevant factors that influence carrier velocity, namely: short-channel electrostatics, saturation velocity effect, graphene/dielectric interface traps, and self-heating effects. Crucially, the model provides microscopic details of channel parameters such as carrier concentration, drift and saturation velocities, allowing us to correlate the observed macroscopic behavior with the local magnitudes. When biasing the GFET so all carriers in the channel are of the same sign resulting in highly concentrated unipolar channel, we find that the larger the drain bias is, both closer the carrier velocity to its saturation value and the higher thef(max)are. However, the highestf(max)can be achieved at biases where there exists a depletion of carriers near source or drain. In such a situation, the highestf(max)is not found in the velocity saturation regime, but where carrier velocity is far below its saturated value and the contribution of the diffusion mechanism to the current is comparable to the drift mechanism. The position and magnitude of the highestf(max)depend on the carrier concentration and total velocity, which are interdependent and are also affected by the self-heating. Importantly, this effect was found to severely limit radio-frequency performance, reducing the highestf(max)from similar to 60 to similar to 40 GHz.
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| 16. |
- Graña-González, A., et al.
(författare)
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Quasi-free (p,2p) reactions in inverse kinematics for studying the fission yield dependence on temperature
- 2023
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Ingår i: FAIR next generation scientists - 7th Edition Workshop : FAIRness2022 - FAIRness2022. - 1824-8039. ; 419
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Konferensbidrag (refereegranskat)abstract
- Despite the recent experimental and theoretical progress in the investigation of the nuclear fission process, a complete description still represents a challenge in nuclear physics because it is a very complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. To improve on the existing data on nuclear fission, we produce fission reactions of heavy nuclei in inverse kinematics by using quasi-free (p,2p) scattering, which induce fission through particle-hole excitations that can range from few to ten's of MeV. The measurement of the four-momenta of the two outgoing protons allows to reconstruct the excitation energy of the fissioning compound nucleus and therefore to study the evolution of the fission yields with temperature. The realization of this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and here some preliminary results are presented.
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| 17. |
- Knyazev, A., et al.
(författare)
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Tl concentration and its variation in a CsI(Tl) crystal for the CALIFA detector
- 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. ; 975
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Tidskriftsartikel (refereegranskat)abstract
- One of the factors that can contribute to the resolution of long, doped inorganic scintillators used for nuclear spectroscopy is the variation of the dopant concentration over the length the detector crystal. In this work an investigation of such potential variations in one of the CsI(Tl) scintillators used in the calorimeter, CALIFA, of the R3B experiment at FAIR, has been performed using particle induced X-ray emission. No statistically significant gradient in doping level was found along the long axis of the investigated sample crystal and the mean value of the Tl concentration was measured to be 0.0839(38)% by weight. This corresponds to a light output of 97.3−1.7 +1.3% relative to the maximum attainable light output according to previously published work. By taking the ±1σ bounds, the 3% statistical spread in the relative light output provides a good reference value of the minimum light-output non-uniformity observed for the CALIFA crystals. If the relative light output is estimated pointwise from a set of Tl concentration measurements a light-output non-uniformity of 4.6(2.4)% results. For a γ-ray energy of 662 keV the deduced variation in Tl concentration contributes with 0.48(6)% to the typical resolution of 7.74(6)% measured with a collimated source along the crystal main axis. The result is of interest for the characterization of the detector system performance and for realistic simulations of the light collection process in detector systems that are used for nuclear spectroscopy and calorimetry.
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| 18. |
- Rodriguez-Sancheza, J. L., et al.
(författare)
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Comprehensive investigation of fission yields by using spallation- and (p,2p)induced fission reactions in inverse kinematics
- 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
- In the last decades, measurements of spallation, fragmentation and Coulex induced fission reactions in inverse kinematics have provided valuable data to accurately investigate the fission dynamics and nuclear structure at large deformations of a large variety of stable and non -stable heavy nuclei. To go a step further, we propose now to induce fission by the use of quasi -free (p,2p) scattering reactions in inverse kinematics, which allows us to reconstruct the excitation energy of the compound fissioning system by using the four-momenta of the two outgoing protons. Therefore, this new approach might permit to correlate the excitation energy with the charge and mass distributions of the fission fragments and with the fission probabilities, given for the first time direct access to the simultaneous measurement of the fission yield dependence on temperature and fission barrier heights of exotic heavy nuclei, respectively. The first experiment based on this methodology was realized recently at the GM/FAIR facility and a detailed description of the experimental setup is given here.
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| 19. |
- Toussaint, Laura, et al.
(författare)
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Clinical practice in European centres treating paediatric posterior fossa tumours with pencil beam scanning proton therapy
- 2024
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Ingår i: RADIOTHERAPY AND ONCOLOGY. - 0167-8140 .- 1879-0887. ; 198
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: As no guidelines for pencil beam scanning (PBS) proton therapy (PT) of paediatric posterior fossa (PF) tumours exist to date, this study investigated planning techniques across European PT centres, with special considerations for brainstem and spinal cord sparing. Materials and methods: A survey and a treatment planning comparison were initiated across nineteen European PBS-PT centres treating paediatric patients. The survey assessed all aspects of the treatment chain, including but not limited to delineations, dose constraints and treatment planning. Each centre planned two PF tumour cases for focal irradiation, according to their own clinical practice but based on common delineations. The prescription dose was 54 Gy(RBE) for Case 1 and 59.4 Gy (RBE) for Case 2. For both cases, planning strategies and relevant dose metrics were compared. Results: Seventeen (89 %) centres answered the survey, and sixteen (80 %) participated in the treatment planning comparison. In the survey, thirteen (68 %) centres reported using the European Particle Therapy Network definition for brainstem delineation. In the treatment planning study, while most centres used three beam directions, their configurations varied widely across centres. Large variations were also seen in brainstem doses, with a brainstem near maximum dose (D2%) ranging from 52.7 Gy(RBE) to 55.7 Gy(RBE) (Case 1), and from 56.8 Gy(RBE) to 60.9 Gy(RBE) (Case 2). Conclusion: This study assessed the European PBS-PT planning of paediatric PF tumours. Agreement was achieved in e.g. delineation-practice, while wider variations were observed in planning approach and consequently dose to organs at risk. Collaboration between centres is still ongoing, striving towards common guidelines.
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