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| 2. |
- Bevilacqua, Riccardo, 1974-, et al.
(författare)
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Light-ion production in the interaction of 175 MeV neutrons with iron and bismuth
- 2011
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Ingår i: Journal of Korean Physical Society.
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Konferensbidrag (refereegranskat)abstract
- We have measured double-differential (angle and energy) cross sections for light-ion (p, d, t, 3He and α) production in the interaction of quasi-monoenergetic 175 MeV neutrons with iron and bismuth. Measurements have been performed at the The Svedberg Laboratory, Uppsala (Sweden), using the Medley setup which allows low-energy thresholds and wide energy and angular ranges. Medley is a spectrometer system consisting of eight three-element telescopes placed at angles from 20◦ to 160◦, in steps of 20◦. Each telescope is composed of two silicon surface barrier detectors and a CsI(Tl) scintillator, to perform particle identification,fully stop the produced light-ions and measure their kinetic energy. The time-of-flight was used to reduce the contribution from the low energy tail in the accepted incident neutron spectrum. We report double-differential production cross sections for protons, deuterons, tritons, 3He and α particles and compare them with model calculations with TALYS-1.2.
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| 3. |
- Bevilacqua, Riccardo, 1974-, et al.
(författare)
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Medley spectrometer for light ions in neutron-induced reactions at 175 MeV
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 646:1, s. 100-107
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Tidskriftsartikel (refereegranskat)abstract
- We have upgraded the Medley spectrometer to measure neutron-induced double differential cross-sections for light-ion production, with neutron energies up to 175 MeV. Measurements were performed at the quasi-monoenergetic neutron beam line at the The Svedberg Laboratory, in Uppsala (Sweden). Medley is a spectrometer system composed of eight three-element telescope detectors; Delta E-E technique is used for particle identification and total kinetic energy measurement. We have improved particle separation and installed new detectors that fully stop ions with kinetic energy up to 170 MeV. To reduce the contribution of the low energy tail in the quasi-monoenergetic neutron spectrum, we have applied time-of-flight techniques and investigated the results for measurements with 175 MeV neutrons. We have investigated the response function of the CsI(Tl) scintillators and describe a method for efficiency correction. We have studied the signal-to-background ratio of the new configuration of the spectrometer and of the collimation system. A method to obtain absolute cross-section normalization, separating the peak neutrons from the low-energy tail, is proposed. Finally we have characterized the 175 MeV quasi-monoenergetic neutron spectrum with the Medley spectrometer. This upgraded configuration has been used in 2007 and 2009 for light-ion production measurements at 175 MeV from C, Si, O, Fe, Bi and U.
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| 4. |
- Bevilacqua, Riccardo, 1974-
(författare)
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Neutron-Induced Light-Ion Production from Iron and Bismuth at 175 MeV
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radioactive waste management is one of the key issues in sustainability of nuclear energy production. Geological repositories represent today the most appropriate solution to long-term management of high-level radioactive waste. Strategies such as Partitioning and Transmutation of spent nuclear fuel may offer a positive impact on geological repositories, by reducing the mass of transuranium elements to be disposed and the time scale for their radiotoxicity. In this scenario, Accelerator Driven Systems (ADS) may play a relevant role as dedicated burners towards sustainable nuclear energy. The NEXT project at Uppsala University contributes to a European effort to improve nuclear data knowledge for transmutation, providing the first experimental neutron induced data in the 100 to 200 MeV energy region. This thesis presents measurements of double-differential cross sections for production of light-ions in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi. Results are compared with model calculations obtained with state-of-the-art nuclear reaction codes; TALYS-1.2, a modified version of JQMD, and MCNP6. Special focus in this work is given to pre-equilibrium emission of composite light-ions. A new energy dependence in the mechanisms described by the Kalbach systematics used in TALYS to account for composite particle emission in the pre-equilibrium stage is proposed. Data show also the need to include multiple pre-equilibrium emission of composite particles, a mechanism now included in TALYS only for protons and neutrons. The JQMD code was recently modified to include a surface coalescence model in the quantum molecular dynamics description of the formation of composite particles. Comparisons of the measured data with results from this modified JQMD code confirm the importance of coalescence mechanisms for the description of the emission spectra of composite particles. Finally, the neutron-induced data are compared with MCNP6 calculations, to contribute to the process of validation and verification of the code.
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| 5. |
- Bevilacqua, Riccardo, 1974-
(författare)
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New neutron data measurements at 175 MeV for Accelerator Driven Systems
- 2011
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Ingår i: Proceedings of the 2011 International Congress on Advances in Nuclear Power Plants. ; , s. 2828-2834
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Konferensbidrag (refereegranskat)abstract
- We have compared TALYS, MCNP6 and quantum molecular dynamics model calculations with preliminary light-ion production data in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi. Data were measured with the Medley setup at the The Svedberg Laboratory, in Uppsala – Sweden. These are the first neutron induced light-ion production data available in the 100 to 200 MeV energy region; these data are relevant for the development of accelerator-driven system technologies, and are needed to ensure a link between high and low energy processes. Model calculations are consistent with some results, but at the moment no code is able to fully predict all the experimental data. Our results show the need of further investigation of neutron-induced reactions in this energy region, in particular to study the production of composite light ions.
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| 6. |
- Bevilacqua, Riccardo, 1974-, et al.
(författare)
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Study of pre-equilibrium emission of light complex particles from Fe and Bi induced by intermediate energy neutrons
- 2011
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 312:SECTION 8, s. 082013-, s. 082013-
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Tidskriftsartikel (refereegranskat)abstract
- We have measured double differential cross sections (DDX) for emission of hydrogen- and helium-isotopes in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi using the Medley setup at the The Svedberg Laboratory (Uppsala, Sweden). We compared experimental DDX with calculations with the TALYS code, which includes exciton model and Kalbach systematics; the code fails to reproduce the emission of complex light ions, generally overestimating it. We propose an correction for the application of the Kalbach phenomenological model in the TALYS code by introducing a new energy dependence for the nucleon transfer mechanism in the pre-equilibrium emission region. Our results suggest also evidence for multiple pre-equilibrium emission of composite particles at 175 MeV.
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| 7. |
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| 8. |
- Hirayama, Shusuke, et al.
(författare)
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Production of protons, deuterons, and tritons from carbon bombarded by 175 MeV quasi mono-energetic neutrons
- 2011
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Ingår i: Progress in Nuclear Science and Technology. - : Atomic Energy Society of Japan. ; 1, s. 69-72
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Tidskriftsartikel (refereegranskat)abstract
- We have measured double-differential yields of protons, deuterons, and tritons produced from carbon induced by 175 MeV quasi mono-energetic neutrons using the MEDLEY setup at the TSL neutron beam facility. The measured data are used for benchmarking of a high-energy nuclear data file, JENDL/HE-2007, and both intra-nuclear cascade (INC) model and quantum molecular dynamics (QMD) calculations.
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| 9. |
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| 10. |
- Ryzhov, I.V., et al.
(författare)
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Fragment-mass distributions in neutron-induced fission of 232Th and 238U at 33, 45, and 60 MeV
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:5, s. 054603-
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Tidskriftsartikel (refereegranskat)abstract
- We have measured fission fragment-mass yields for neutron-induced fission of Th-232 and U-238 at energies 32.8, 45.3, and 59.9 MeV. The experiments were done at quasimonoenergetic neutron beams of the Cyclotron Research Center at Louvain-la-Neuve. To detect the fission fragments, a multisection Frisch-gridded ionization chamber was used. The measurement and data analysis techniques are discussed in detail. The obtained mass yields are compared to model calculations with the intermediate-energy nuclear reaction code MCFX. The MCFX code is used to calculate the fraction of fissioning nuclei after cascade, preequilibrium, and statistical reaction stages. The formation of mass distributions is considered as a result of oscillations of the mass-asymmetry degree of freedom in the potential well calculated with the temperature-dependent shell correction method. The experimental results as well as the results of the model calculations demonstrate that the probability of symmetric fission increases with incident neutron energy for both nuclei. The comparison also shows that the symmetric fission is more enhanced for thorium than for uranium with increasing neutron energy. We also compare U-238 results with available experimental data; the Th-232 data were measured for the first time.
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