Neutron radiative capture cross section for sodium with covariance analysis

Abstract

The neutron radiative capture cross sections measurement has been carried out for the $$^{23}$$ 23 Na nucleus in the neutron energy region from 0.6 to 3.2 MeV using the neutron activation technique followed by off-line $$\\gamma $$ γ -ray spectrometry. The measurement was made relative to the $$^{115}$$ 115 In( n,n $$\\prime $$ ′ $$\\gamma $$ γ ) $$^{115}\\hbox {In}^{m}$$ 115 In m reference monitor reaction cross section. The neutrons were produced via the $$^{7}$$ 7 Li( p,n ) $$^{7}$$ 7 Be reaction. Detailed uncertainty propagation has been performed using the covariance analysis, and the measured cross sections are being reported with their uncertainties, covariance, and correlation matrix. The necessary corrections have been made for the low background neutron energy contribution, $$\\gamma $$ γ -ray true coincidence summing, and self-attenuation process. The obtained neutron spectrum averaged cross sections of $$^{23}$$ 23 Na(n, $$\\gamma $$ γ ) $$^{24}$$ 24 Na are discussed and compared with the existing cross sections data retrieved from the EXFOR database. EMPIRE-3.2 and TALYS-1.9 calculations were performed in order to determine the radiative capture cross section in this energy region. The present results are also compared with the evaluated nuclear data from ENDF/B-VIII.0, TENDL-2019, IRDFF-1.05, JENDL-4.0, and JEFF-3.3. The obtained cross section results are in good agreement with existing experimental data, evaluated libraries, and reaction models for the highest energy points (2.11 and 3.13 MeV), while the lowest-energy point at 0.61 MeV underestimates them.