| 1. |
- Pawlowski, P., et al.
(författare)
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Neutron recognition in the LAND detector for large neutron multiplicity
- 2012
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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. ; 694, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment. (C) 2012 Elsevier B.V. All rights reserved.
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| 2. |
- Audouin, L., et al.
(författare)
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High-precision measurement of isotopic fission yields of 236 U
- 2018
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 193
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Konferensbidrag (refereegranskat)abstract
- We report on the second SOFIA experiment, dedicated to the fission yields of 236U∗, analog to 235U(n,f). The measurement is based on the inverse kinematics method, using a relativistic, secondary beam of 236U. Both fission fragments are identified in mass and charge in the SOFIA recoil spectrometer. The obtained isotopic yields are compared with existing spectroscopy measurements and the elemental yields are used to discuss the treatment of the even-odd effect with energy in nuclear data libraries.
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| 3. |
- 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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| 4. |
- Chatillon, A., et al.
(författare)
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Experimental study of nuclear fission along the thorium isotopic chain: From asymmetric to symmetric fission
- 2019
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 99:5
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Tidskriftsartikel (refereegranskat)abstract
- The inverse kinematics technique, applied to radioactive beams and combined to the Coulomb excitation method, is a powerful tool to study low-energy fission. A novel experimental setup was developed within the R3B/SOFIA (Reactions with Relativistic Radioactive Beams/Studies On FIssion with Aladin) collaboration to identify in mass and atomic numbers both fission fragments in coincidence. These new data provide elemental, isobaric, and isotonic yields for the fission along the thorium isotopic chain. Results are also compared to previous measurements using either the same reaction mechanism or thermal-neutron induced fission. This latter comparison permits to probe the influence of the excitation energy in the fission process.
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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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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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| 7. |
- 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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| 8. |
- Martin, J. F., et al.
(författare)
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Studies on fission with ALADIN Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI
- 2015
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 51:12, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism.
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| 9. |
- Pellereau, E., et al.
(författare)
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Accurate isotopic fission yields of electromagnetically induced fission of U 238 measured in inverse kinematics at relativistic energies
- 2017
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 95:5, s. 054603-
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Tidskriftsartikel (refereegranskat)abstract
- SOFIA (Studies On Fission with Aladin) is a novel experimental program, dedicated to accurate measurements of fission-fragment isotopic yields. The setup allows us to fully identify, in nuclear charge and mass, both fission fragments in coincidence for the whole fission-fragment range. It was installed at the GSI facility (Darmstadt), to benefit from the relativistic heavy-ion beams available there, and thus to use inverse kinematics. This paper reports on fission yields obtained in electromagnetically induced fission of U238.
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| 10. |
- Benlliure, J., et al.
(författare)
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New experimental approaches to investigate the fission dynamics
- 2016
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Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. - 9780735414112 ; 1753
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Konferensbidrag (refereegranskat)abstract
- The first ever achieved full identification of both fission fragments, in atomic and mass number, made it possible to define new observables sensitive to the fission dynamics along the fission path up to the scission point. Moreover, proton-induced fission of 208Pb at high energies offers optimal conditions for the investigation of dissipative, and transient effects, because of the high-excitation energy of the fissioning nuclei, its low angular momentum, and limited shape distortion by the reaction. In this work we show that the charge distribution of the final fission fragments can constrain the ground-to-saddle dynamics while the mass distribution is sensitive to the dynamics until the scission point.
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| 11. |
- Boutoux, G., et al.
(författare)
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The SOFIA Experiment
- 2013
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 47, s. 166-171
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Konferensbidrag (refereegranskat)abstract
- SOFIA (Study On FIssion with Aladin) is an innovative experimental programme on nuclear fission carried out at GSI. In August 2012, we used relativistic secondary beams of neutron-deficient actinides and pre-actinides provided by the FRS and studied their fission, induced by electromagnetic interaction, in inverse kinematics. This experiment will provide for the first time complete isotopic yields (nuclear charge and mass) for both fragments over a broad range of fissioning nuclei from 238Np down to 183Hg. In this article, we discuss the experimental set-up and present promising preliminary results.
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| 12. |
- Chatillon, A., et al.
(författare)
-
Accurate measurements of fission-fragment yields in U-234,U-235,U-236,U-238(gamma,f) with the SOFIA set-up
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759819706 ; 111
-
Konferensbidrag (refereegranskat)abstract
- SOFIA (Studies On Fission with Aladin) is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (gamma,f) electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in U-234,U-235,U-236,U-238(gamma,f) reactions.
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| 13. |
- Gorbinet, T., et al.
(författare)
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A sample of the results of the first SOFIA experiment
- 2015
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 101-106
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Konferensbidrag (refereegranskat)abstract
- The first SOFIA experiment (Studies On FIssion with Aladin) was performed in August 2012 at GSI. The fission of several neutron-deficient actinides and pre-actinides was induced in flight at 700 A MeV by electromagnetic excitation. The use of inverse kinematics provides both high detection and high geometrical efficiency. The complete identification of both fission fragments in coincidence (nuclear charge and mass) was obtained over a broad range of fissioning nuclei. After a short introduction and description of the experimental setup, the quality of the charge and mass separation is presented, followed by some results concerning the Coulex-induced fission of U-234 and U-235. (C) 2015 Published by Elsevier B.V.
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| 14. |
- Grente, L., et al.
(författare)
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The SOFIA experiment: Measurement of 236U fission fragment yields in inverse kinematics
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 122:01006
-
Konferensbidrag (refereegranskat)abstract
- The SOFIA (Studies On FIssion with Aladin) experiment aims at measuring fission-fragments isotopic yields with high accuracy using inverse kinematics at relativistic energies. This experimental technique allows to fully identify the fission fragments in nuclear charge and mass number, thus providing very accurate isotopic yields for low energy fission of a large variety of fissioning systems. This report focuses on the latest results obtained with this set-up concerning electromagnetic-induced fission of 236U.
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| 15. |
- Pellereau, E., et al.
(författare)
-
SOFIA: An innovative setup to measure complete isotopic yield of fission fragments
- 2013
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 62
-
Konferensbidrag (refereegranskat)abstract
- We performed an experiment dedicated to the accurate isotopic yield measurement of fission fragments over the whole range. SOFIA exploits the inverse kinematics technique: using heavy ion beams at relativistic energies, fission is induced by Coulomb excitation in a high-Z target. The fragments are emitted forward and both of them are identified in charge and mass. The setup will be presented, as well as preliminary spectra. © Owned by the authors, published by EDP Sciences, 2013.
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| 16. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Complete characterization of the fission fragments produced in reactions induced by Pb 208 projectiles on proton at 500A MeV
- 2015
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 91:6
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Tidskriftsartikel (refereegranskat)abstract
- The two fragments produced in fission reactions induced by Pb208 projectiles impinging on a liquid hydrogen target at 500AMeV have been fully identified in coincidence. The experiment was performed at GSI Darmstadt, where the combined use of the inverse kinematics technique with an efficient detection setup permitted one to detect and to fully identify the fission fragments in a range from Z=27 to Z=52. The corresponding isotopic cross sections and velocities of the fission fragments were measured with high accuracy. The results are compared to state-of-the-art model calculations that reproduce the measured observables. Correlations between the two fragments were used to assess the role of charge polarization and the excitation energy gained by the nascent fragments using the neutron excess of the final fragments. The analysis of the average velocities of the fission fragments allowed us to parametrize the distance between the two fission fragments at scission as a function of the size of the fissioning system.
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| 17. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Constraining the level density using fission of lead projectiles
- 2015
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 92:4
-
Tidskriftsartikel (refereegranskat)abstract
- The nuclear level density is one of the main ingredients for the statistical description of the fission process. In this work, we propose to constrain the description of this parameter by using fission reactions induced by protons and light ions on Pb208 at high kinetic energies. The experiment was performed at GSI (Darmstadt), where the combined use of the inverse kinematics technique with an efficient detection setup allowed us to measure the atomic number of the two fission fragments in coincidence. This measurement permitted us to obtain with high precision the partial fission cross sections and the width of the charge distribution as a function of the atomic number of the fissioning system. These data and others previously measured, covering a large range in fissility, are compared to state-of-the-art calculations. The results reveal that total and partial fission cross sections cannot unambiguously constrain the level density at ground-state and saddle-point deformations and additional observables, such as the width of the charge distribution of the final fission fragments, are required.
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| 18. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Dissipative effects in fission investigated in complete kinematics measurements
- 2017
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759890200 ; 146
-
Konferensbidrag (refereegranskat)abstract
- The study of dissipative effects in fission has been carried out with fusion-fission reactions by using a limited number of observables, such as the fission probabilities, the mass distribution of the fission fragments, or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus in this kind of reaction could affect the conclusions drawn from such experiments. In this work, we propose to investigate the fission dynamics by the use of spallation reactions on 208Pb because the fissioning systems are produced with low angular momentum, small deformations, and high excitation energies, enhancing the dissipative effects. The complete kinematics measurements of the fission fragments and light-charged particles were performed by the use of the SOFIA setup combined with the inverse kinematics technique, allowing us for the first time a full indentification in atomic and mass number of the two fission fragments. These measurements permit us to define new fission observables for the investigation of the temperature and deformation dependencies of the dissipation parameter.
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| 19. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Dissipative effects in fission investigated with proton-on-lead reactions
- 2016
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9788874381012 ; 117, s. Art. no. 08017-
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Konferensbidrag (refereegranskat)abstract
- The complete kinematic measurement of the two fission fragments permitted us to investigate dissipative effects at large deformations, between the saddle-point and the corresponding scission configurations. Up to now, this kind of study has only been performed with fusionfission reactions using a limited number of observables, such as the mass distribution of the fission fragments or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus could affect the conclusions drawn from such experiments. In this work, the use of spallation reactions, where the fissioning systems are produced with low angular momentum, small deformations and high excitation energies, favors the study of dissipation, and allowed us to define new observables, such as postscission neutron multiplicities and the neutron excess of the final fission fragments as a function of the atomic number of the fissioning system. These new observables are used to investigate the dissipation at large deformations.
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| 20. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Fission dynamics at high excitation energies investigated in complete kinematics measurements
- 2017
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 863:1, s. Article no 012047-
-
Konferensbidrag (refereegranskat)abstract
- Light-charged particles emitted in proton-induced fission reactions on 208 Pb have been measured at different kinetic energies: 370A, 500A, and 650A MeV. The experiment was performed by the SOFIA collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light-charged particles in coincidence with fission fragments. The data were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.
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| 21. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Fission of highly excited nuclei investigated in complete kinematic measurements
- 2013
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 62
-
Konferensbidrag (refereegranskat)abstract
- Fission is an extremely complex mechanism that requires a dynamical approach to describe the evolution of the process in terms of intrinsic and collective excitations of the nuclear constituents. In order to determine these effects a complex experimental setup was mounted at GSI, which allowed us for the first time the full identification in charge and mass of all fission fragments thanks to a magnetic separation and the use of the inverse kinematic technique. Moreover, we also measured the neutron multiplicities and the light-charged particles emitted in coincidence with fission. These complete kinematic measurements will be used to define sensitive observables to dissipative and transient effects in fission. In this manuscript we present the first results for the total fission cross sections. © Owned by the authors, published by EDP Sciences, 2013.
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| 22. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Light charged particles emitted in fission reactions induced by protons on Pb-208
- 2016
-
Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 94:3
-
Tidskriftsartikel (refereegranskat)abstract
- Light charged particles emitted in proton-induced fission reactions on Pb-208 have been measured at different kinetic energies: 370A, 500A, and 650A MeV. The experiment was performed by the SOFIA Collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light charged particles in coincidence with fission fragments. This measurement allowed us, for the first time, to obtain correlations between the light charged particles emitted during the fission process and the charge distributions of the fission fragments. These correlations were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.
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| 23. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
-
Presaddle and postsaddle dissipative effects in fission using complete kinematics measurements
- 2016
-
Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 94:6
-
Tidskriftsartikel (refereegranskat)abstract
- A complete kinematics measurement of the two fission fragments was used for the first time to investigate fission dynamics at small and large deformations. Fissioning systems with high excitation energies, compact shapes, and low angular momenta were produced in inverse kinematics by using spallation reactions of lead projectiles. A new generation experimental setup allowed for the first full and unambiguous identification in mass and atomic number of both fission fragments. This measurement permitted us to accurately determine fission cross sections, the charge distribution, and the neutron excess of the fission fragments as a function of the atomic number of the fissioning system. These data are compared with different model calculations to extract information on the value of the dissipation parameter at small and large deformations. The present results do not show any sizable dependence of the nuclear dissipation parameter on temperature or deformation.
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| 24. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Proton-induced fission cross sections on Pb-208 at high kinetic energies
- 2014
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 90:6, s. Art. no. 064606-
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Tidskriftsartikel (refereegranskat)abstract
- Total fission cross sections of Pb-208 induced by protons have been determined at 370A, 500A, and 650A MeV. The experiment was performed at GSI Darmstadt where the combined use of the inverse kinematics technique with an efficient detection setup allowed us to determine these cross sections with an uncertainty below 6%. This result was achieved by an accurate beam selection and registration of both fission fragments in coincidence which were also clearly distinguished from other reaction channels. These data solve existing discrepancies between previous measurements, providing new values for the Prokofiev systematics. The data also allow us to investigate the fission process at high excitation energies and small deformations. In particular, some fundamental questions about fission dynamics have been addressed, which are related to dissipative and transient time effects.
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| 25. |
- Rodriguez-Sanchez, J. L., et al.
(författare)
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Transient effects in fission investigated with proton-on-lead reactions in complete kinematic measurements
- 2015
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 157-162
-
Konferensbidrag (refereegranskat)abstract
- Proton-induced fission of Pb-208 has been investigated at 370, 500 and 650 A MeV in complete kinematic measurements. The experiment was performed at GSI Darmstadt where the combined use of the inverse kinematics technique with an efficient detection setup allowed to measure for the first time the atomic and mass number of both fission fragments. The performed measurement together with different model calculations allow us to investigate dissipative and transient effects in the fission process and the dependence on temperature and deformation of the dissipation strength beta. The use of spallation reactions with lead projectiles favours this study due to its high excitation energy and low angular momentum. (C) 2015 The Authors. Published by Elsevier B.V.
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