Abstract
An account is given of a series of study to accurately determine the cross section of the 99Tc (n, γ) 100Tc reaction for thermal neutrons. Methods used are an activation analysis in which γ rays in 100Ru are examined, and analyses of ground-state transitions in 100Tc. To reduce uncertainty of the cross section obtained in the activation measurement, an attempt was made to accurately determine emission probabilities of γrays in 100Ru.