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Alpha-decay from the 3.5 eV isomer of 229Th

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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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  1. R. G. Burke, P. E. Garrett, Tpao Qu, R. A. Naumann, Phys. Rev., C42(2) (1990) R499.

    Google Scholar 

  2. R. G. Helmer, C. W. Reich, Phys. Rev., C49(4) (1994) 1845.

    Google Scholar 

  3. E. V. Tkalya, A. N. Zherikhin, V. I. Zhudov, Phys. Rev., C61 (2000) 064308.

    Google Scholar 

  4. G. M. Irvin, K. H. Kim, Phys. Rev. Lett., 79 (1997) 990.

    Google Scholar 

  5. D. S. Richardson, D. M. Benton, D. E. Evans, J. A. R. Grifithm, G. Tungate, Phys. Rev. Lett., 80 (1998) 3206.

    Google Scholar 

  6. S. B. Utter, P. Beiersdorfer, A. Barnesw, R. W. Lougheed, J. R. Crespo Lopez-Urrutia, J. A. Becker, M. S. Weiss, Phys. Rev. Lett., 82 (1999) 505.

    Google Scholar 

  7. R. W. Shaw, J. P. Young, S. P. Cooper, O. F. Webb, Phys. Rev. Lett., 82 (1999) 1109.

    Google Scholar 

  8. Table of Isotopes, Vol. 2, 8th ed., R. B. Firestone and V. S. Shirley (Eds), John Wiley & Sons, Inc., New York, 1996, p. 2711.

    Google Scholar 

  9. T. Mitsugashira, M. Hara, Y. Suzuki, M. Watanabe, S. Hirai, Y. Okada, A. Mori, J. Radioanal. Nucl. Chem., 239 (1999) 345.

    Google Scholar 

  10. L. I. Schiff, Phys. Rev., 126 (1962) 1112.

    Google Scholar 

  11. M. Asai, private communication.

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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).

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