Alpha decay of221Rn and217Po; level structure of217Po and the213Pb ground state

Alpha recoil sources of221Rn were used to study the level structure of217Po and the ground state of213Pb. The half-life of217Po was measured to be (1.6±0.2) s. When combined with unpublished data, an alpha-decay hindrance factor (HF) of 1.3 was obtained for the alpha-decay, strongly suggesting a g9/2 → g9/2 transition between217Po and213Pb ground states. Alpha-gamma coincidence studies confirm the previously observed 11/2+ band head in217Po. It is suggested that an unobserved 9/2+ ground state lies below the 11/2+ state in217Po and an attempt is made to observe connecting links between these two parts of the217Po level scheme.