Abstract:
The low-energy nuclear structure and decay properties of the neutron-deficient isotopes 195At and 191Bi have been studied. 195At was produced in the reaction 142Nd(56Fe,p2n)195At and 191Bi as the daughter activity of 195At. The activities were implanted in a position-sensitive silicon detector after being separated from the primary beam by a gas-filled recoil separator. The 1/2+ intruder state was determined to be the ground state in 195At with an alpha-decay energy of E α = 6953(3) keV and a half-life T 1/2 = 328(20) ms. Another state with an alpha-decay energy E α = 7075(4) keV and a half-life T 1/2 = 147(5) ms was found to decay to a 148.7(5) keV excited state in 191Bi for which a spin and parity of 7/2- were deduced. Consequently, the same 7/2- character was assigned to the initial state at 32(7) keV in 195At on the basis of unhindered alpha-decay. The 9/2- state, being the ground state in heavier odd-mass astatine isotopes, was not observed.
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Received: 16 September 2002 / Accepted: 19 December 2002 / Published online: 25 March 2003
RID="a"
ID="a"e-mail: heikki.kettunen@phys.jyu.fi
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ID="b"Present address: Laboratory of Radiochemistry, P.O. Box 55, FIN-00014, University of Helsinki, Finland.
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ID="c"Present address: Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki, Finland.
Communicated by W. Henning
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Kettunen, H., Enqvist, T., Leino, M. et al. Investigations into the alpha-decay of 195At. Eur Phys J A 16, 457–467 (2003). https://doi.org/10.1140/epja/i2002-10130-9
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DOI: https://doi.org/10.1140/epja/i2002-10130-9