Neutron Capture Cross-Section Measurement of Rhodium in the Energy Region from 0.003 eV to 80 keV by Linac Time-of-Flight Method

The neutron capture cross section of rhodium has been measured in the energy region from 0.003 eV to 80 keV by the neutron time-of-flight method with a 46-MeV electron linear accelerator of the Kyoto University, Research Reactor Institute. An assembly of Bi₄Ge₃O₁₂ (BGO) scintillators, which was composed of 12 pieces of BGO and placed at a distance 12.7 ± 0.02 m from the neutron source, was employed as a total energy absorption detector for the prompt capture gamma-ray measurement from the sample. In order to determine the neutron flux impinging on the capture sample, a plug of ¹⁰B powder sample and the ¹⁰B(n, ) standard cross section were used.

The existing experimental data and evaluated capture cross sections in ENDF/B-VI, JENDL-3.2, and JEF-2.2 have been compared with the current measurement. Popov and Shapiro obtained poor energy resolution data in the resonance region with a lead slowing-down spectrometer. Furthermore, their data are a little higher than the current values above ~1 keV. The experimental data measured by Weston et al., Hockenbury et al., Macklin and Halperin, Fricke et al., and Block et al. are somewhat higher than the current values. The data measured by Moxon and Rae are somewhat lower than the current values above ~100 eV. The data measured by Wisshak et al. and Bokhovko et al. are in general agreement with the measurement above 4 keV within the experimental error. The evaluated data in ENDF/B-VI, JENDL-3.2, and JEF-2.2 have been in good agreement with the current result, although the JENDL-3.2 and the JEF-2.2 values are somewhat lower than the measurement in the cross section minimum region from 10 to 100 eV.

The thermal neutron cross sections (2200 m/s values) measured by Seren et al. and Walker et al. are in good agreement with the current measurement (133.0 ± 0.93 b) within the experimental error. Other experimental data and the evaluated data are discrepant by 9 to 29% from the measurement.