STUDY ON EXPERIMENTAL CROSS SECTIONS FOR REACTIONS 174Yb(n,γ)175Yb AND 55Mn(n,γ)56Mn AT NEW ENERGIES OF 0.0334 AND 0.0536 eV USING NEUTRONS FROM TRIGA NUCLEAR REACTOR

Abstract

The neutron capture cross sections of 1 74Yb(n,γ)1 75Yb and 55Mn(n,γ)56Mn reactions at 0.0334 eV and 0.0536 eV energies were experimentally measured for the first time using monochromatic neutrons from a neutron diffractometer and a neutron spectrometer at TRIGA Mark II research reactor. The 197Au(𝑛𝛾198Au reaction was used as a monitor reaction to determine the neutron beam intensity. High-resolution gamma-ray spectrometry system was used to measure the radioactivity of the product nuclides. After considering all the correction factors such as neutron self-shielding and gamma attenuation effects, the resultant cross sections obtained for the reaction 1 74Yb(n,γ)1 75Yb at 0.0334 eV and 0.0536 eV energies are 56.8 ± 3.7 b and 44.2 ± 2.6 b, respectively. The determined experimental values for the reaction at 0.0334 eV and 0.0536 eV are in agreement with the theoretically evaluated data libraries of JENDL-4.0 and ENDF/B-VIII. However, experimentally determined data in this work are around 45% less than the theoretically evaluated JEFF-3.3 data. Similarly, the resultant cross sections obtained for the reaction 55Mn(n,γ)56Mn at 0.0334 eV and 0.0536 eV neutron energies are 11.07±0.60 b and 9.03±0.49 b, respectively. The resultant data for the two reactions were extrapolated to the 0.0253 eV energy by assuming 1/v dependence in the thermal energy region. The extrapolated data at 0.0253 eV for 174Yb(n,γ)175Yb and 55Mn(n,γ)56Mn reactions are 64.8±2.9 b and 12.93±0.99 b, respectively. The data obtained from this study at 0.0253 eV for the reactions are compared with the integrally measured values reported in the literature and different theoretically evaluated data libraries such as ENDF/B-VIII, JENDL-4.0, ROSFOND-2010 and JEFF-3-3. The data obtained from this study at 0.0253 eV for 174Yb(n,γ)175Yb reaction validates the excitation functions of JENDL-4.0 and ENDF/B-VIII data libraries. However, data obtained from this study do not support the JEFF-3-3 data library ii at thermal energy region for this reaction. On the other hand, the resultant cross sections for 55Mn(n,γ)56Mn reaction at 0.0253 eV, 0.0334 eV and 0.0536 eV are consistent with those data libraries within the uncertainty limits. The new cross sectional data obtained from this study are convenient to check the evaluated excitation functions at thermal energy region to resolve discrepancies of the data for the studied reactions which can be used for the proper assessment of the reactor criticality safety. Moreover, the obtained data from this study will also be useful to measure activity distribution, therapeutic radioisotope production and studies related to the interaction of neutrons with matter for the studied targets. This study will also encourage crosssection measurements for various reactions, at different energies in the thermal energy region, at many places in the world where neutron diffractometer and spectrometer are installed.