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Alpha-decay from the 3.5 eV isomer of 229Th

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Abstract

The alpha-decay of a low energy isomer of 229Th at about 3.5 eV was sought by producing it through the (g,n) reaction on a 230Th target. Thorium isotopes in the reaction products were isolated and purified by anion exchange chromatography in a concentrated nitric acid medium to remove lanthanides fission products. The thorium fraction was further purified by samarium fluoride coprecipitation and the precipitate was mounted as a source for a-spectroscopy. Decaying a-signals were observed in the energy region that was expected for 229mTh, i.e., between 4.83 and 5.08 MeV. The half-life of the decaying component was determined from repeated experiments to be 13.9±3 hours.

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Mitsugashira, T., Hara, M., Ohtsuki, T. et al. Alpha-decay from the 3.5 eV isomer of 229Th. Journal of Radioanalytical and Nuclear Chemistry 255, 63–66 (2003). https://doi.org/10.1023/A:1022267428310

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  • DOI: https://doi.org/10.1023/A:1022267428310

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