Eur. Phys. J. A (2005) 25: 355-363
https://doi.org/10.1140/epja/i2005-10141-0

Original Article

Isomers of astrophysical interest in neutron-deficient nuclei at masses A = 81, 85 and 86

¹ Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40014, Finland
² St. Petersburg State University, 198904, St. Petersburg, Russia
³ Petersburg Nuclear Physics Institute, 188300, Gatchina, Russia
⁴ GSI, Postfach 110552, D-64291, Darmstadt, Germany
⁵ Michigan State University, 48824, East Lansing, MI, USA

^* e-mail: anu.kankainen@phys.jyu.fi

Received: 21 June 2005
Accepted: 16 August 2005
Published online: 26 September 2005

Abstract

Decay properties of neutron-deficient exotic nuclei close to A=80 have been investigated at the IGISOL facility. The studied nuclei, ⁸¹Y, ⁸¹Sr, ^81mKr, ⁸⁵Nb, ⁸⁵Zr, ⁸⁶Mo and ⁸⁶Nb, were produced by a ³²S beam from the Jyväskylä isochronous cyclotron on ⁵⁴Fe and ^natNi targets. The internal conversion coefficient for a 190.5 keV isomeric transition in ^81mKr has been measured and the internal transition rate has been determined. The internal transition rate has been used to estimate a neutrino capture rate on ⁸¹Br, which yields a log ft of 5.13±0.09 for the reaction ⁸¹Br( ν, e ^-)^81mKr. A new isomer with a half-life of 3.3±0.9 s has been observed in ⁸⁵Nb. The existence of an earlier reported isomer with a half-life of 56 s in ⁸⁶Nb has not been confirmed.