Abstract
Low-lying excited levels of231Th fed through α-decay of235U were investigated by using α-γ and γ-γ coincidence technique. From the analyses for co-relating energy levels and transition intensities, we found that the most favorable transition from 205.3 keV ([631]7/2) level that is fed by the most dominant α transition from235U is 19.6 keV transition (205.3 keV [631]7/2−→185.7 keV [631]5/2−). We also found that the transition probability of 109.2 keV, 205.3 keV [631]7/2−→96.1 keV [633]9/2+, was corrected to be weak. These findings can explain why the 185.7 keV γ-ray is so strongly observed, 0.57 photons/ga, in the γ-spectrum associated with the α-decay of235U. The decay scheme of231Th levels previously reported has been modified according to the present analysis.
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Yuki, H., Nakazawa, K., Ohtsuki, T. et al. Reinvestigation of low-lying levels of231Th. J Radioanal Nucl Chem 239, 151–153 (1999). https://doi.org/10.1007/BF02349547
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DOI: https://doi.org/10.1007/BF02349547