6533b872fe1ef96bd12d37cd

RESEARCH PRODUCT

Thermal neutron capture cross section of the radioactive isotopeFe60

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Background: Fifty percent of the heavy element abundances are produced via slow neutron capture reactions in different stellar scenarios. The underlying nucleosynthesis models need the input of neutron capture cross sections.Purpose: One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive isotopes, such as $^{60}\mathrm{Fe}$ with a half-life of $2.60\ifmmode\times\else\texttimes\fi{}{10}^{6}$ yr. To reproduce this $\ensuremath{\gamma}$ activity in the universe, the nucleosynthesis of $^{60}\mathrm{Fe}$ has to be understood reliably.Methods: An $^{60}\mathrm{Fe}$ sample produced at the Paul Scherrer Institut (Villigen, Switzerland) was activated with thermal and epithermal neutrons at the research reactor at the Johannes Gutenberg-Universit\"at Mainz (Mainz, Germany).Results: The thermal neutron capture cross section has been measured for the first time to ${\ensuremath{\sigma}}_{\text{th}}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}0.226\phantom{\rule{4pt}{0ex}}{(}_{\ensuremath{-}0.049}^{+0.044})\phantom{\rule{4pt}{0ex}}\text{b}$. An upper limit of ${\ensuremath{\sigma}}_{\text{RI}}l0.50\phantom{\rule{4pt}{0ex}}\text{b}$ could be determined for the resonance integral.Conclusions: An extrapolation towards the astrophysically interesting energy regime between $kT=10$ and 100 keV illustrates that the $s$-wave part of the direct capture component can be neglected.