Energy splitting of the ground-state doublet in the nucleus 229Th.
The energy splitting of the 229Th ground-state doublet is measured to be 7.6+/-0.5 eV, significantly greater than earlier measurements. Gamma rays produced following the alpha decay of 233U (105 muCi) were counted in the NASA/electron beam ion trap x-ray microcalorimeter spectrometer with an experimental energy resolution of 26 eV (FWHM). A difference technique was applied to the gamma-ray decay of the 71.82 keV level that populates both members of the doublet. A positive correction amounting to 0.6 eV was made for the unobserved interband decay of the 29.19 keV state (29.19-->0 keV).
Beck
B R
BR
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Becker
J A
JA
Beiersdorfer
P
P
Brown
G V
GV
Moody
K J
KJ
Wilhelmy
J B
JB
Porter
F S
FS
Kilbourne
C A
CA
Kelley
R L
RL