Measurement of prompt fission neutron spectrum for spontaneous fission of Cf252 using γ multiplicity tagging

Abstract

The prompt fission neutron spectrum from spontaneous fission of $^{252}\mathrm{Cf}$ is an integral part of several aspects of nuclear data. Not only is the spectrum itself of interest, but neutron detectors often use the spectrum for calibration, and other prompt fission neutron spectra are measured as a ratio to $^{252}\mathrm{Cf}$. Therefore, reducing the uncertainties in this spectrum will allow for more accurate nuclear data to be available across a wide range of fields. The prompt fission neutron spectrum for the spontaneous fission of $^{252}\mathrm{Cf}$ was measured at Rensselaer Polytechnic Institute using the multiple $\ensuremath{\gamma}$ tagging method with a 18.4-ng fission sample. An EJ-301 liquid scintillator fast neutron detector was used to measure the high energy portion of the spectrum, 0.5--7 MeV, and a thin EJ-204 plastic scintillator was used to measure the low energy portion of the spectrum, from 50 keV to 2 MeV. These spectra both show good agreement with the current evaluation of $^{252}\mathrm{Cf}$ and have low associated uncertainties providing a new high precision measurement that helps reduce the uncertainties in the prompt fission neutron spectrum for the spontaneous fission of $^{252}\mathrm{Cf}$.