Total prompt γ -ray emission in fission of U235 , Pu239,241 , and Cf252

Abstract

The total prompt $\ensuremath{\gamma}$-ray energy distributions for the neutron-induced fission of $^{235}\mathrm{U}$ and $^{239,241}\mathrm{Pu}$ in the neutron energy range of 0.025 eV -- 100 keV and the spontaneous fission of $^{252}\mathrm{Cf}$ were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) in coincidence with the detection of fission fragments by a parallel-plate avalanche counter. DANCE is a highly segmented, highly efficient 4$\ensuremath{\pi}$ $\ensuremath{\gamma}$-ray calorimeter. Corrections were made to the measured distribution by unfolding the two-dimension spectrum of total $\ensuremath{\gamma}$-ray energy vs multiplicity using a simulated DANCE response matrix generated with a geometrical model of the detector arrays and validated with the $\ensuremath{\gamma}$-ray calibration sources. The mean values of the total prompt $\ensuremath{\gamma}$-ray energy, determined from the unfolded distributions, are $\ensuremath{\sim}$20% higher than those of early measurements for all the fissile nuclei studied. The implication for the $\ensuremath{\gamma}$ heating in nuclear reactors is discussed.