New prompt spectral<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>-ray data from the reaction<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow/><mml:mn>252</mml:mn></mml:msup></mml:math>Cf(sf) and its implication on present evaluated nuclear data files

We present results from new spectral prompt $\ensuremath{\gamma}$-ray measurements from the spontaneous fission of ${}^{252}$Cf. Apart from one recent experiment, about four decades have passed since the last dedicated experiments were reported in the literature. Hence, there was a need for a revision. We have measured prompt fission $\ensuremath{\gamma}$ rays with both cerium-doped LaBr${}_{3}$ and CeBr${}_{3}$ scintillation detectors, both of which exhibit excellent timing and good energy resolution. The emission yield was determined to be ${\ensuremath{\nu}}_{\ensuremath{\gamma}}=(8.30\ifmmode\pm\else\textpm\fi{}0.08)$/fission and ${\ensuremath{\nu}}_{\ensuremath{\gamma}}=(8.31\ifmmode\pm\else\textpm\fi{}0.10)$/fission, with the average energy of ${\ensuremath{\epsilon}}_{\ensuremath{\gamma}}=(0.80\ifmmode\pm\else\textpm\fi{}0.01)$ MeV and ${\ensuremath{\epsilon}}_{\ensuremath{\gamma}}=(0.80\ifmmode\pm\else\textpm\fi{}0.01)$ MeV and total energy of ${E}_{\ensuremath{\gamma},\mathrm{tot}}=(6.64\ifmmode\pm\else\textpm\fi{}0.08)$ MeV and ${E}_{\ensuremath{\gamma},\mathrm{tot}}=(6.65\ifmmode\pm\else\textpm\fi{}0.12)$ MeV, with the LaBr${}_{3}$ and CeBr${}_{3}$ detectors, respectively. Since the results from the two detectors are in excellent agreement and confirm the historical data, but not those in the present evaluated nuclear data files, we strongly recommend an update.

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