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Neutron production in Pb/U assembly irradiated by p+, d+ at 0. 7 – 2
Neutron production in Pb/U assembly irradiated by p+, d+ at 0.7 – 2.52 GeV Ondřej Svoboda Nuclear Physics Institute, Academy of Sciences of Czech Republic Department of Nuclear Reactors, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague
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Outline Energy plus Transmutation project
Proton and deuteron experiments MCNPX simulations Experiment Simulation Conclusion
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Energy plus Transmutation project
Main aim: study of transmutation of FP and HA by spallation neutrons Our tasks: study of neutron production in thick, heavy target with fissionable blanket irradiated by light ions in GeV range perform relevant Monte-Carlo simulations make comparisons between experimental data and simulations
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Energy plus Transmutation - setup
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Proton and deuteron experiments
Until now : - p+ experiments – energies 0.7, 1, 1.5, and 2 GeV Analyzed & simulated - d+ experiments - energies 1.6 and 2.52 GeV Preliminary results, simulations in progress On Nuclotron accelerator (Joint Institute for Nuclear Research, Dubna, Russia) Intensity ~ 1010/bunch, 1013 total Irradiation time: about 8 h Deuterons represent a new challenge for us – difficulties both in experiment and in simulation!
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Beam monitors 27Al beam monitor – (p,3pn)24Na – well known sexp
– (d,3p2n)24Na – only one value in our region sexp= ± 1.50 mbarn (2330 MeV) natCu beam monitor – (p,X) – many isotopes 58Co, 56Co, 55Co, 52Mn, 48Cr, 48Sc, 44mSc, 57Ni, 48V, 43K, 61Cu, etc. – well known sexp – (d,X) – no sexp in our energy region!
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Detection of neutrons Al Au Bi Co In Ta Reaction E thresh [MeV]
Half-life 197Au (n,2n) 196Au 8.1 6.183 d 197Au (n,3n) 195Au 14.8 186.1 d 197Au (n,4n) 194Au 23.2 38.02 h 197Au (n,5n) 193Au 30.2 17.65 h 197Au (n,6n) 192Au 38.9 4.94 h 197Au (n,7n) 191Au 45.7 3.18 h EXFOR data
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Placement of activation foils
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Gamma spectra measurement and evaluation
Yields of produced isotopes computed with respect to all corrections: decay during cooling, measurement, irradiation unequable irradiation coincidences non point-like emittors detector deadtime detector efficiency
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Longitudinal distributions of isotopes produced in Au and Al foils (e
Longitudinal distributions of isotopes produced in Au and Al foils (e.g., 2.52 GeV deuterons)
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Radial distributions of isotopes produced in Au and Al foils (e.g., 2.52 GeV deuterons)
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Description of U/Pb assembly in MCNPX
Simulations – MCNPX 2.6.C Different models available in the code – a lot of combinations! IntraNuclear Cascade stage: Bertini, Isabel, INCL4, CEM03 models Pre-equilibrium stage: Multistage Pre-equilibrium Exciton model Evaporation/fission: Dresner, ABLA models Description of U/Pb assembly in MCNPX
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Experiment versus Simulations – models comparison
example of 194Au in radial distribution, 1 GeV proton
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Experiment versus Simulations
relative ratios of experimental and simulated yields (normalized to this foil) MCNPX setting: Bertini + Dresner
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Thank you for your attention..
Summary Experiment × simulation: Protons – good agreement for Ep ≤ 1 GeV – big difference for Ep ≥ 1.5 GeV Deuterons – experiment analysis in progress – simulations problematic, only INCL4 can simulate E >2 GeV, but very time consuming Future plans: Perform proton experiments with higher energies Continue deuteron experiments Detailed analysis of possible sources of uncertainties to find out “where is the problem?” Thank you for your attention..
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