Covariance analysis on the thermal neutron capture cross sections using an Am-Be neutron source

We measured the thermal cross sections of Ga-71(n,gamma)Ga-72 using an Am-Be neutron source having strength of 4x10(7)neutrons/sec using the two monitor reactions Au-197(n,gamma)Au-198 and Mn-55(n,gamma)Mn-56, and obtained 4.07 +/- 0.27 b and 3.97 +/- 0.31 b as the values measured relative to Au and Mu neutron captures, respectively. We constructed their covariance matrix by taking into account the correlation of parameters which are not independent in derivation of these two thermal cross sections (e.g., Ga sample weight, decay data of Ga-72, detector efficiency of gamma-ray emitted from Ga-72) The off-diagonal weighted mean of the two cross sections 4.04 +/- 0.27 b was derived from the two thermal cross sections and their covariance matrix.