1. Joint IAEA-ICTP Workshop on Nuclear Reaction Data for Advanced Reactor Technologies Student’s presentation Calculation of correction factors for neutron capture cross section measurements Pham Ngoc Son, Nuclear Research Institute, VAEC, Vietnam

2. The average capture cross sections,, at an average neutron spectrum energy can be measured relative to the standard capture cross section of 197 Au by activation method: Introduction f c : correction factors

3. Introduction Correction factors must be introduced to take into account: Multi-scattering of neutron in sample Self-shielding effect Resonance capture with neutrons in low energy background region Monte Carlo simulation Exactly estimation of neutron spectrum (unfolding method)

4. Computer programs

6. Th-232 69.2eV 70.4eV

7. Computer programs Unfolding neutron spectrum of 54keV filtered neutron beam at Dalat Reactor

8. Computer programs Unfolding neutron spectrum of 148.3keV filtered neutron beam at Dalat Reactor

9. Computer programs In a neutron activation experiment, the reaction rate will be measured indirectly, by detection of emitted decay gamma rays from the product nucleus: The first term of the reaction rate accounts for the effect of neutrons in the primary region of spectrum. The second term accounts for the effect of neutron in background region. Can be Measured by using a HPGe Detector

10. Experimental results Nucleus 54keV 148.3keV This workENDFThis workENDF Sm-1520.345010.34380. 258320. 25030 Sm-1540.1521 0.21999 0.0841 0.08496 La-1390.022070.028190.009910.01422 Ir-1911.013331.0060.547970.6282 Ir-1930.637210.63490.37190.3726 Nd-1460.0883 0.09919 0.0642 0.72845 Nd-1480.1189 0.11058 0.0936 0.84968 Results of measured capture cross section for some nuclei

11. Thank you for your attention!