Application of BGO Scintillators to Absolute Measurement of Neutron Capture Cross Sections between 0.01eV and 10eV

Applying a total energy absorption γ-ray detector composed of 12 bricks (5×5cm2, 7.5cm thick) of BGO scintillators, the absolute measurement of capture cross sections for Au and Sb has been made in an energy region between 0.01 and 10eV using the linac time-of-flight method. Incident thermal neutron flux was absolutely determined by using the BGO detection system with a Sm sample. T6 extend the neutron flux measurement from the thermal neutron region to higher neutron energies, the 10B(n, αγ) reaction was applied. Absolute capture yield for the relevant capture sample was obtained by the saturated capture yield at a large resonance of the sample. Gold was selected to investigate the application of the BGO detection system to the absolute measurement of the capture cross sections, since the 197Au(n, -γ)198Au reaction cross section is a well known standard one.The result of the 197Au(n, -γ)198Au reaction cross section showed good agreement with the evaluated data in JENDL Dosimetry File and ENDF/B-VI. Then, the detection system was applied to the Sb(n, γ) cross section measurement. Antimony has a large scattering-to-capture cross section ratio comparing to that of gold. Theresult showed good agreement with the evaluated data in JENDL-3.2 and ENDF/B-VI.