| 1. |
- 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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| 2. |
- 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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| 3. |
- Göttsche, M., et al.
(författare)
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C/O Kerma coefficient ratio for 96 MeV neutrons deduced from microscopic measurements
- 2010
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 45:10, s. 1139-1141
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Tidskriftsartikel (refereegranskat)abstract
- Double-differential cross sections for neutron-induced light-ion production at 96 MeV have been measured for a variety of nuclei at The Svedberg Laboratory. Using the measured cross-section data, we deduce the Kerma coefficient from carbon and oxygen for p, d, t, He-3 and alpha particles. In order to get the total Kerma for C and O, we add GNASH calculation values where experimental data are not available and obtain a Kerma coefficient of 7.85 +/- 0.63 fGy m(2) for carbon and 7.09 +/- 0.57 fGy m(2) for oxygen. The C/O Kerma coefficient ratio then becomes 1.11 +/- 0.11. In addition we determine the Kerma ratio between ICRU muscle and A-150, again adding calculations with the GNASH code where no experimental data are available, and obtain a value of 0.98 +/- 0.05. While the Kerma coefficients for carbon and oxygen do not agree with the prediction in ICRU Report 63, the ratio values are in good agreement with existing predictions.
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| 4. |
- 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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| 5. |
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| 6. |
- 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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