The 3$_{1}^{-}$ level in $^{56}$Fe

ORAL

Abstract

The question whether the 3076.2-keV, (3$^{-}$), or the 4509.6~keV, 3$^{-}$, is the first 3$^{-}$ level in $^{56}$Fe is important for reaction model calculations [see M. B. Chadwick {\it et al.}, Nucl. Data Sheets {\bf 118}, 1 (2014)]. The inclusion in the databases of the 3076.2-keV level will be discussed. A work by A. M. Demidov {\it et al.} [Phys. Atom. Nucl. {\bf 67}, 1884 (2004)] using the $^{56}$Fe(n,n$^{\prime}{\gamma}$) reaction and fast neutrons from a reactor, reported that the 3076.2-keV state does not exist and triggered the present work, where $\gamma$-$\gamma$ coincidence data in $^{56}$Fe, which are more definitive, were recorded with the GEANIE spectrometer comprised of 26 high-purity Ge detectors. The pulsed beam of the Los Alamos Neutron Science Center's WNR facility provided fast neutrons impinging on a $^{56}$Fe target. As we reported in Phys. Rev. C {\bf 81}, 037304 (2010), our experiment supported the assignment of the 4509.6~keV level as the first 3$^{-}$ state, with no observation in the gated spectra of the two transitions that were reported to decay out of the 3076.2-keV level by Z. Guo {\it et al.} [Nucl. Phys. {\bf A540}, 117 (1992)]. A plan to repeat the (p,$\gamma$) reaction that reported the observation of these two transitions will be discussed.

Authors

  • N. Fotiades

    Los Alamos National Laboratory, LANL, NM, USA

  • M. Devlin

    Los Alamos National Laboratory, LANL, NM, USA

  • R.O. Nelson

    Los Alamos National Laboratory, LANL, NM, USA