Direct observation of bound state beta decay of bare 207Tl at FRS-ESR

Abstract

We observed the bound-state beta decay of fully ionized 207Tl nuclei circulating in a storage ring. It is the first direct measurement of bound-state beta decay. 207Tl nuclei were produced by the projectile fragmentation, separated by fragment separator and injected in the storage ring. Using the Schottky diagnostics the decay time spectrum of bare 207Tl and hydrogen like 207Pb ions which are the daughter nuclei of bound-state beta decay were measured. Observed decay-rate ratio between bound-state and continuous-state beta decay was 0.18(2). This value is consistent with the theoretical calculation.