β-delayed γ-ray spectroscopy of 203,204Au and 200-202Pt

The β decay of five heavy, neutron-rich nuclei, 203,204Pt and 200-202Ir, has been investigated following relativistic cold fragmentation reactions of lead projectiles using the FRS+RISING setup at GSI. This paper reports on the study of the low-lying states in the decay daughter nuclei 203,204Au and 200-202Pt. The characteristic γ rays for each nucleus have been determined using β-delayed γ-ray spectroscopy. Tentative level schemes, relative intensities, and apparent β feedings are provided. These data are compared with shell-model calculations, which indicate a substantial contribution to the total β strength from high-energy first-forbidden β-decay transitions in this mass region.