The assignment of the slow-neutron-produced activities of thallium and the dual disintegration of radium E

Recoil experiments with a strong source of RaE (21 mC initial activity) electrolytically deposited on platinum show that an activity of half-value period 4-2 min. is obtained. This observation indicates that Ra E undergoes dual disintegration with an o: ,B branching ratio of the order of 5 x 1O-7. Rough absorption measurements favour the identification of the activity with the 4-2-min. activity produced in the (n, y) and (d, p) reactions with thallium, and therefore require assignment of the latter to 206T1, contrary to earlier suggestions. Consideration of the energies involved shows that the postulated a: ,B branching ratio has roughly the value which would be predicted on the basis of accepted regularities.