Decay of 201-203Ra and 200-202Fr

Decay properties of the neutron-deficient nuclides Ra201-203 and Fr200-202 were investigated using alpha- and gamma-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of Fe-56 projectiles with enriched Sm-147 and 149Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The a decay from the (3/2(-)) state in Ra-201 was identified with an energy E-alpha = 7842(12) keV and half-life T-1/2 = 8(-4)(+40) ms. Ambiguous decay properties for Ra-202 from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of E-alpha = 7722(7) keV and T-1/2 = 3.8(-0.8)(+1.3) ms. New short-lived isomeric states were identified in Fr-200 and Fr-201 with half-lives of 0.6(-0.2)(+0.5) mu s and 0.7(-0.2)(+0.5) mu s, respectively. A tentative spin and parity of 13/2(+) were assigned to the latter. One event attributed to beta-delayed fission of Fr-200 was observed.