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 svoboda@ujf.cas.cz

Outline Energy plus Transmutation project Proton and deuteron experiments MCNPX simulations Experiment  Simulation Conclusion

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

Energy plus Transmutation - setup

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!

Beam monitors 27Al beam monitor – (p,3pn)24Na – well known sexp – (d,3p2n)24Na – only one value in our region sexp= 15.25 ± 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!

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

Placement of activation foils

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

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)

Radial distributions of isotopes produced in Au and Al foils (e.g., 2.52 GeV deuterons)

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

Experiment versus Simulations – models comparison example of 194Au in radial distribution, 1 GeV proton

Experiment versus Simulations relative ratios of experimental and simulated yields (normalized to this foil) MCNPX setting: Bertini + Dresner

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..