Revised neutron capture cross section of Pb by combining activation method and high-precision thermal ionization mass spectrometry

Nakamura, Shoji  ; Shibahara, Yuji*; Shizuma, Toshiyuki*; Kimura, Atsushi   ; Endo, Shunsuke   ; Rovira Leveroni, G.  

In view of the requirement for accurate cross-section data of the stable Pb isotopes in order to discuss the neutron moderation effect and neutron economy in the design of accelerator-driven systems, the authors previously derived the thermal-neutron capture cross-section of Pb by using thermal ionization mass spectrometry to be 0.5370.030 barn. The uncertainty in the Pb/Pb isotope ratio determined by mass spectrometry was 4.3, bringing the total uncertainty to 5.6. This study demonstrated that a new silica-gel emitter used in mass spectrometry improved isotope ratio precision to 1. This enabled us to determine the reaction rate with 1 accuracy, which exceeds the accuracy of conventional activation analysis. Owing to improved accuracy in mass spectrometry, the uncertainty has been reduced and the value of isotope ratio has changed slightly. Accordingly, the authors report a revised Pb neutron capture cross-section of 0.5120.019 barn.