Investigation of γ-multiplicity spectra and neutron capture cross-sections of 232Th in the energy region 21.5-215 eV

Applying multiplicity spectrometry and using U-238 as the reference sample, the coincidence multiplicity spectra and the radiative capture cross-sections of Th-232 were measured for the energy range 21.5-215 eV. The gamma rays originating from neutron capture were detected by 16 sections of liquid scintillator, where the coincidence multiplicity ranged from 1 to 16. It seems that the gamma-multiplicity spectra of the s resonances of Th-232 in the above energy region are almost identical. The radiative capture cross-sections were determined for each s resonance and for the three energy groups 21.5-46,5, 46.5-100 and 100-215 eV. Our group average cross-sections agree well with the values calculated with the resonance parameters given in the evaluated data libraries ENDF/B-VI, JENDL-3 and BROND-2. (C) 2000 Elsevier Science B.V. All rights reserved.