Alpha-decay studies of the new isotopes 191At and 193At

H. Kettunen; T. Enqvist; T. Grahn; P.T. Greenlees; P. Jones; R. Julin; S. Juutinen; A. Keenan; P. Kuusiniemi; M. Leino; A.-P. Leppänen; P. Nieminen; J. Pakarinen; P. Rahkila; J. Uusitalo

doi:10.1140/epja/i2002-10162-1

2022 Impact factor 2.7

Hadrons and Nuclei

Eur. Phys. J. A (2003) 17: 537-558
https://doi.org/10.1140/epja/i2002-10162-1

Original Paper

Alpha-decay studies of the new isotopes ¹⁹¹At and ¹⁹³At

H. Kettunen^*, T. Enqvist, T. Grahn, P.T. Greenlees, P. Jones, R. Julin, S. Juutinen, A. Keenan, P. Kuusiniemi, M. Leino, A.-P. Leppänen, P. Nieminen, J. Pakarinen, P. Rahkila and J. Uusitalo

Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40014, Jyväskylä, Finland

^* e-mail: heikki.kettunen@phys.jyu.fi

Abstract

Detailed alpha-decay studies have been performed for the neutron-deficient isotopes ¹⁹¹At and ¹⁹³At. The nuclei were produced in fusion-evaporation reactions of ⁵⁴Fe and ⁵⁶Fe ions with a ¹⁴¹Pr target. The fusion products were separated in-flight using a gas-filled recoil separator and implanted into a position-sensitive silicon detector. The isotopes were identified using position, time and energy correlations between the implants and subsequent alpha-decays. Three alpha-decaying states were identified for ¹⁹³At and two for ¹⁹¹At. The spin and parity of the initial states in the astatine isotopes were deduced based on unhindered alpha-decays to states in the bismuth daughter nuclei. In both astatine isotopes the 1/2⁺ intruder state was determined to be the ground state and a 7/2^- state to be the first-excited state. In ¹⁹³At the alpha-decay of the 13/2⁺ state was observed in coincidence with a previously known gamma-ray transition from the 13/2⁺ state in the corresponding daughter nucleus ¹⁸⁹Bi. In ¹⁸⁷Bi and ¹⁸⁹Bi low-lying 7/2^- states were observed for the first time via alpha-decay of the mother nuclei.