Abstract:
The light actinide nuclei
219U and
216Ac were produced in fusion-evaporation reaction using a
183W target and
40Ar beam. After recoiling from thin target, the fusion-evaporation residues were separated by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure) and transported into the focal plane detector systems, where their impantations and decays were measured. The method of searching for
\alpha 
-decay chains was used to identify the nuclei. In this work, the known
\alpha decay of
219U was measured with improved precision and the
\alpha -particle energy of 9 763(15) keV and a half-life of 60(7) μs was determined. In addition, two new
\alpha -decay lines at 9 246(17) keV and 8 975(17) keV were observed and assigned as the decays from the ground state of
219U to the (
5/2 ^- 
) and (
3/2 ^- 
) states of
215Th, respectively. The existence of an
\alpha -decaying isomeric state in
216Ac was also confirmed.
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