Abstract
With the exception of illinium, thulium and lutecium all the rare earth elements have been bombarded with slow and fast neutrons. The fast neutrons were obtained from the Li+D reaction. Deuterons of 6.3 Mev were produced by the cyclotron at the University of Michigan. The following periods for electron emission have been observed: (31 hr.), (19 hr.), (84 hr.), (2.0 hr.), (21 min.), (12.5 hr.), (21 min.), (46 hr.), (9.2 hr.), (3.3 hr.), (2.5 hr.), (47 min.), (30 hr.), (12 hr.) and (5.1 hr.) The following periods for positron emission have been observed: (2.1 min.), (3.5 min.), (27 hr.), (3.6 min.), (2.2 min.) and (1.1 min.). There seems to be at least two isotopes which are isomeric: one is (3.5 min., 17 hr.) and the other is (2.1 hr., 14 hr.). From radioactivity data it is necessary to postulate the existence of four new stable isotopes: , , and . With the fast neutron bombardment seventeen type of reactions have been found.
- Received 15 January 1938
DOI:https://doi.org/10.1103/PhysRev.53.437
©1938 American Physical Society