Determination of Thermal Neutron Cross Section and Resonance Integral for 64Zn (n, γ) 65Zn Reaction by Activation Method

Abstract

Abstract:  Despite the growing availability of resonance integral data for stable nuclides, several isotopes produced via (n,γ) reactions still lack precise or consistent experimental data. Accurate nuclear data are essential for reactor physics, neutron flux characterization, and analytical applications. This study reports the thermal neutron cross section and resonance integral of the ⁶⁴Zn(n,γ)⁶⁵Zn reaction, measured using the activation method at the Nigerian Research Reactor-1 (NIRR-1), Ahmadu Bello University, Zaria. High-purity powdered ZnO samples were irradiated under both bare and 1-mm cadmium-covered conditions to separate thermal and epithermal neutron contributions. A monitor with a well-known neutron cross section was used as a single comparator to minimize neutron self-shielding and to quantify zinc concentration. Irradiated samples were measured using a calibrated p-type high-purity germanium (HPGe) detector at a source-to-detector distance of 2.2 cm. The thermal neutron cross section of the ⁶⁴Zn(n,γ)⁶⁵Zn reaction was determined to be 0.726 ± 0.02 barn, while the resonance integral was found to be 1.47 ± 0.05 barn at a cadmium cut-off energy of 0.55 eV. The cadmium ratio (R_Cd) was measured as 7.01 ± 0.99, consistent with previous work in other NIRR-1 channels. These results agree well with evaluated nuclear data, such as 0.726 ± 0.02 barn (De Corte and Simonits, 2003), 0.76 ± 0.02 barn (Mughabghab, 2003), and 1.45–1.428 barn for the resonance integral from various libraries, while earlier experimental cross sections ranged from 0.72 ± 0.04 to 1.23 ± 0.12 barn and resonance integrals from 0.76 ± 0.08 to 3.10 ± 0.02 barn.The agreement of measured activities, cadmium ratio, and derived cross sections demonstrates the stability of the thermal neutron flux and the high analytical capability of the NIRR-1 LEU core. The results provide reliable nuclear data for ⁶⁴Zn and validate the use of powdered ZnO as a monitor in thermal neutron activation studies.