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Simulations on the setup “Energy plus Transmutation”

Simulations on the setup “Energy plus Transmutation”. Mitja Majerle m ajerle@ujf.cas.cz. - can they predict the experimental results ?. Modelling of basic processes (microscopic scale). Experiments (macroscopic scale). Simulation codes. Models – particle interactions, transport

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Simulations on the setup “Energy plus Transmutation”

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  1. Simulations on the setup“Energy plusTransmutation” Mitja Majerle majerle@ujf.cas.cz - can they predict the experimental results ?

  2. Modelling of basic processes (microscopic scale) Experiments (macroscopic scale) WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  3. Simulation codes • Models – particle interactions, transport • Cross-section libraries • Problem setup • Particles, processes can be followed WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  4. Simulations, how/what we calculate • MCNPX code v. 2.4.0 Input : • setup geometry • starting conditions • neutron distribution • Cross-section libraries (Au, Al - ENDF; Bi - experimental; Iodine - ?) • masses of produced elements or B-values WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  5. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  6. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  7. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  8. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  9. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  10. Control detectors for studying the setup - with (n,g) we study LE neutrons (flat part) – odd numbers -(n,4n) threshold is 23 MeV – even numbers WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  11. ENERGY + TRANSMUTATION • INFLUENCE OF THE SETUP PARTS • simplifications of the setup description • different parts of the setup • SYSTEMATIC ERROR (not accurately known exp. conditions) • beam geometry • reactions with protons • inserted detectors • ACCURACY OF SIMULATION • intra-nuclear cascade model used in calculations • PARAMETERS OF THE SETUP • the number of produced neutrons (spallation, fission, ..) • k (criticality) WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  12. The simplifications of the blanket • No influence on high energy neutrons (even numbers) • Box has no influence on HE neutrons ! • Box blurs differences. • 40%, 10% WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  13. Polyethylene, Cd layer • The spectra were taken inside the 1st and 3rd gap. • No influence on HE neutrons. absorption by238U resonance capture WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  14. Aluminum and iron holders, upper iron plate • Two simulations with and without Al, Fe components. The results do not differ outside the limits of statistical error - (HE 3%, LE 10%) • The upper iron plate reduces the number of neutrons for 2%. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  15. The wooden plate • Wooden plate under the target(1+2cm,0.5kg/l). • Without box. • Detectors from top to bottom. • Asymmetry 5% => negligible wood influence. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  16. Systematic error • Systematic error is made, because we can/did not measure all the experimental conditions. • Simulations give us the estimation of the error. • In simulations we vary experimental conditions in limits of the accuracy with which we measured them. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  17. Beam parameters influence • Beam profile is approximated with Gaussian distribution (good only near the beam center !). • We must always count with beam displacement. • Experimentally determined beam profiles and displacement (V Wagner using monitor and track detector data – for profile mainly I Zhuk data): WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  18. Beam profile • Simulations with 3mm, 3cm homogenous beams and with a beam with gaussian profile (FWMH=3cm). • Differences only for few percents. • Not important. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  19. Beam displacement • Beam displaced for 3,5,8, and 10 mm. • Differences between results up to tens of %Displacement must be measured as accurately as possible ! WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  20. The influence of protons • Activation detectors could also be activated by protons. • Cross-sections for reactions with protons are not included in MCNPX. • Estimations from Phasotron experiment and neutron/proton ratio : in gaps, near the central axis ca. 10% of activation is due to protons. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  21. The influence of detectors on neutron field • Metal plate on top reduces the number of neutrons only for 2%. Our detectors are much smaller. • Golden strap (2mm, 4mm) in the first gap has no influence on detectors in other gaps. • Only 0.1 mm thick golden strap is an obstacle for thermal neutrons : it can reduce the production rates of reactions with thermal neutrons inside the same gap for 20%. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  22. The influence of plastic foils for detectors on neutron field • The 4mm and 8mmpolyethylene on which were placed the detectors for 1.5 GeV experiments had effect on LE neutrons. • Au in sandwich of 2 Bi foils => no influence. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  23. Intra-Nuclear Cascade models • In MCNPX 2.4.0 are 3 models (above 150 MeV): • Bertini • CEM • Isabel • The differences are up to 50% (standard, our detectors). WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  24. Experimentally we cannot measure these. For 1.5 GeV experiment, neutron production : 29 in nuc. Interactions 8 in (n,xn) 14 prompt fission. Together 54 neutrons per 1 proton. Without box 49 neutrons. KCODE calculations for criticality : k=19.2% k was calculated also by S.R. Hashemi-Nezhad - 22%. If we add polyethylene wall at the back, k stays the same. Beyond experimental results: neutrons per proton, criticality,.. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  25. Neutrons per proton with beam energy • Neutrons per 1 proton and per 1 MeV in the beam • Box adds ca. 5 neutrons • Saturation • Peak at 1500 MeV WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  26. K.D. Tolstov, “Some Aspects of Accelerator Breeding,” JINR preprint, 18-89-778, Dubna, Russia, 1989 WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

  27. Conclusions • The differences between experiment and simulations : systematic errors vs. models/cross-sections • On the way to qualify the models and cross-section libraries. Thank you. WORKSHOP ON PHYSICS OF ADS FOR ENERGY AND TRANSMUTATION (January 23-26, 2003)

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