publication . Article . 1994

An excited state ofTh229at 3.5 eV

C. W. Reich; R. G. Helmer;
Open Access
  • Published: 01 Apr 1994
It has been known for many years that the first excited state of $^{229}\mathrm{Th}$ lies close to the ground state. Originally this energy was given as 0.1 keV; later, the authors reported a value of -1\ifmmode\pm\else\textpm\fi{}4 eV. In an attempt to improve the value for this level energy, we have remeasured the energies of a number of \ensuremath{\gamma} rays from $^{223}\mathrm{U}$ whose positions in the $^{229}\mathrm{Th}$ level scheme can be used to establish it. Compared with our earlier study, we have considered more \ensuremath{\gamma} rays in $^{229}\mathrm{Th}$, used more well-measured energy calibration and reference lines, used more detectors, use...
arXiv: Astrophysics::High Energy Astrophysical Phenomena
free text keywords: Systematic error, Spectral line, Ground state, Physics, Excited state, Atomic physics, Relative energy
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