Neutron Capture in Fluorine Below 1500 keV

Abstract

Neutron time-of-flight radiative capture data taken at the Oak Ridge electron linear accelerator have been analyzed for single-level resonance parameters. Eleven resonances were found, with parameters as indicated, listing ${E}_{0}$ (keV), $J$ value assumed, and ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}}$ (eV) in order: 27.07 (2) 1.4 \ifmmode\pm\else\textpm\fi{} 0.3, 48.7 (1) 1.7 \ifmmode\pm\else\textpm\fi{} 0.4, 97.0 (1) \ensuremath{\le}6.0 \ifmmode\pm\else\textpm\fi{} 1.8, 269 (2) 3.5 \ifmmode\pm\else\textpm\fi{} 0.8, 270 (1) \ensuremath{\le} 4.4, 386 (1) \ensuremath{\ge} 7\ifmmode\pm\else\textpm\fi{}2, 490.5 (0) \ensuremath{\ge} 10\ifmmode\pm\else\textpm\fi{}3, 595 (2) \ensuremath{\ge} 7 \ifmmode\pm\else\textpm\fi{} 2, 1460 (1) \ensuremath{\ge} 11\ifmmode\pm\else\textpm\fi{}3. Values of total width were also found for these resonances. Two resonances are very narrow and their capture areas yield estimates of $g{\ensuremath{\Gamma}}_{n}$. At 43.5 keV, $g{\ensuremath{\Gamma}}_{n}=0.086\ifmmode\pm\else\textpm\fi{}0.02$ eV if $J\ensuremath{\ge}1$ or ${\ensuremath{\Gamma}}_{n}=0.42\ifmmode\pm\else\textpm\fi{}0.1$ eV if $J=a$, and, at 173.5 keV, $g{\ensuremath{\Gamma}}_{n}=0.35\ifmmode\pm\else\textpm\fi{}0.10$ eV. The increase of nearly an order of magnitude in radiative width with increasing energy up to 600 keV is notable. Twelve large resonances between 1600 and 5000 keV were not analyzed for capture because of detector sensitivity to the inelastic scattering channels which open in that energy region.