Improved Value for the Energy Splitting of the Ground-State Doublet in the Nucleus 229mTh

Conference · Thu Jul 16 00:00:00 EDT 2009

OSTI ID:964521

Beck, B R; Wu, C; Beiersdorfer, P; Brown, G V; Becker, J A; Moody, K J; Wilhelmy, J B; Porter, F S; Kilbourne, C A; Kelley, R L

We have made an improved estimate of the {sup 229m}Th isomer energy. The new value, 7.8(5) eV, includes an estimate of possible spectral contamination effects due to the out-of-band E2 transition from the 42.43-keV 7/2+ member of the [633] ground state band to the 3/2+ [631] {sup 229m}Th bandhead and so a weak and unresolved transition a few eV different in energy. We estimate a 2% branching ratio for this unobserved transition in the 42.43-keV 7/2+ [633] deexcitation. The excitation of the {sup 229m}Th level is increased from the previously reported value of 7.6(5) eV to the new best value of 7.8(5) eV when this branch is included in the analysis.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 964521
• Report Number(s): LLNL-PROC-415170; TRN: US0903866
• Resource Relation: Conference: Presented at: 12th International Conference on Nuclear Reaction Mechanisms, Varenna, Italy, Jun 15 - Jun 19, 2009
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BRANCHING RATIO
CONTAMINATION
EXCITATION
GROUND STATES
ISOMERS
NUCLEAR REACTIONS