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M&C 2005 Avignon September 12-15, 2005 MCNPX STUDIES OF SPALLATION NEUTRON PRODUCTION ON A THICK LEAD TARGET. Mitja Majerle NPI CAS Řež, The Czech Republic. Introduction. Generally : Experiments with high-energy protons on heavy targets (~ADS), spallation neutrons, direct beam
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M&C 2005 AvignonSeptember 12-15, 2005MCNPX STUDIES OF SPALLATION NEUTRON PRODUCTION ON A THICK LEAD TARGET Mitja Majerle NPI CAS Řež, The Czech Republic
Introduction • Generally : • Experiments with high-energy protons on heavy targets (~ADS), spallation neutrons, direct beam • We measure transmutation possibilities, neutron fields, we compare data with model simulations • Focus – The PHASOTRON experiment : • Protons, neutron field (threshold detectors) • ... and the simulations • What and how we calculate • Comparison with the experiment • The influence of the setup parts M&C 2005, Avignon, September 12-15, 2005
Neutrons and protons react with detectors: (n,g), (n,2n), (n,xn), (n,a), (p,n), (p,a), ... • Yields of produced elements are detectable in g-detectors M&C 2005, Avignon, September 12-15, 2005
Experimental results B=Number of produced nuclei in 1 g of material per one incident proton Preliminary results M&C 2005, Avignon, September 12-15, 2005
Simulations, how/what we calculate • MCNPX code v. 2.4.0 (on Linux, parallel computing) • Input : • setup geometry • starting conditions • Output 1: • neutron distribution • Cross-section libraries (Au, Al - ENDF; Bi - experimental; Iodine - ?) • Output 2: • masses of produced elements or B-values M&C 2005, Avignon, September 12-15, 2005
Neutron spectra + cross-sections • We can convolute the calculated neutron spectrum with the cross-section for a given reaction (SSW+HTAPE3X+convolution). 197Au(n,2n)196Au 27Al(n,a)24Na 197Au(n,g)198Au • Computer can convolute the spectrum with cross-sections and outputs B (F4+FM tally). M&C 2005, Avignon, September 12-15, 2005
Calculations vs. experiment Calculated values in comparison with the experiment for 27Al(n,a)24Na Ratios between calculated and experimental values for 24Na, 196Au, 194Au M&C 2005, Avignon, September 12-15, 2005
Influence of the setup parts No walls • Concrete walls : • Neutrons are moderated and reflected back Walls M&C 2005, Avignon, September 12-15, 2005
Influence of other simplifications • Extensive calculation tests on PHASOTRON and EPT setup revealed that : • HTAPE3X and F4 methods results do not always agree. • Beam profile and displacement influence the neutron field (3 mm ~ 5%). • The use of different models (BERTINI, CEM, ISABEL) ~ 10%. • Detectors minimally influence the neutron field. • Metal holders, tables, ... have minimal influence. • ... M&C 2005, Avignon, September 12-15, 2005
Parallel processing • The use of parallel processing (PVM) speeds up our calculations significantly. M&C 2005, Avignon, September 12-15, 2005
Conclusion • We try to imitate an ADS systems with the setup • We can describe new, similar systems with the computer with the accuracy (50%) Thank you. M&C 2005, Avignon, September 12-15, 2005