Lawrence Berkeley National Laboratory

Total thermal radiative neutron cross sections have been measured on natural and enriched isotopic targets containing Li6,7,Be9,B10,11,C12,13, and N14,15 with neutron beams from the Budapest Reactor. Complete neutron capture γ-ray decay schemes were measured for each isotope. Absolute transition probabilities have been determined by a least-squares fit of the transition intensities, corrected for internal conversion, to the (n,γ) decay schemes. The γ-ray cross sections were standardized using stoichiometric compounds containing both the isotope of interest and another element whose γ-ray cross sections are well known. Total cross sections σ0 were then determined for each isotope from the γ-ray cross sections and transition probabilities. For the B11(n,γ)B12 reaction decay transition probabilities were determined for the γ rays from B12 (t1/2=20.20 ms) β- decay.