Original scientific paper
Excitation of the low-lying isomeric level in 229Th
Kinney H. Kim
; Physics Department, NCCU, Durham, NC 27707, U. S. A.
George M. Irwin
; Physics Department, Lamar University, Beaumont, TX 77710, U. S. A.
Abstract
Gamma-ray spectroscopy measurements have revealed the presence of an isomeric excited state in 229Th only (3.5 ± 1.0) eV above the ground state, and recent measurements with a high resolution detector have resulted in the value of (7.6 ± 0.5) eV. The state is of interest due to the unique atomic-nuclear interactions which should govern its decay. The state is also of interest as excitation of the level allows the study of processes important in the development of gamma-ray lasers. Although a small number of experiments have been done in an attempt to observe the de-excitation of the isomeric level populated following alpha decay of 233U, the results remain controversial and inconclusive, mainly due to ambiguities in samples used by various researchers. To date no attempts have been made to excite the lowlying level from the ground state of 229Th, nor has there been a systematic study of 233U in various sample forms with suitable uranium control isotopes to look for evidence of the decay of the low-lying level consistent with theoretical predictions. We present a comparison of some possible excitation techniques, including the resonant (M¨ossbauer effect) and non-resonant (broadband) methods, and propose some possible experiments.
Keywords
isomeric state in 229Th; atomic-nuclear interaction
Hrčak ID:
304726
URI
Publication date:
1.11.2011.
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