1. Czech Technical University in Prague, Horská 3a/22, 12800 Prague 2, Czech Republic
2. Joint Institute for Nuclear Research, 141980 Dubna, Russia
3. Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay, France
4. Comenius University in Bratislava, SK-842 15 Bratislava, Slovakia