April 1, 1994 Journal article Open Access

Helmer, R. G.; Reich, C. W.

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  <dc:creator>Helmer, R. G.</dc:creator>
  <dc:creator>Reich, C. W.</dc:creator>
  <dc:date>1994-04-01</dc:date>
  <dc:description>It has been known for many years that the first excited state of Th229 lies close to the ground state. Originally this energy was given as &lt;0.1 keV; later, the authors reported a value of -1±4 eV. In an attempt to improve the value for this level energy, we have remeasured the energies of a number of γ rays from U223 whose positions in the Th229 level scheme can be used to establish it. Compared with our earlier study, we have considered more γ rays in Th229, used more well-measured energy calibration and reference lines, used more detectors, used detectors with better low-energy resolution, more closely matched the counting rates in the γ-ray peaks whose relative energy is measured, and specifically considered certain systematic errors. More than 111 γ-ray spectra have been measured. From this large set of measurements we have deduced a value of 3.5±1.0 eV for the energy of this level.</dc:description>
  <dc:identifier>https://zenodo.org/record/1233767</dc:identifier>
  <dc:identifier>10.1103/physrevc.49.1845</dc:identifier>
  <dc:identifier>oai:zenodo.org:1233767</dc:identifier>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>https://creativecommons.org/publicdomain/zero/1.0/legalcode</dc:rights>
  <dc:title>An excited state of Th 229 at 3.5 eV</dc:title>
  <dc:type>info:eu-repo/semantics/article</dc:type>
  <dc:type>publication-article</dc:type>
</oai_dc:dc>