A Measurement of the 18O(⍺,n)21Ne Reaction for Nuclear Astrophysics*

For passive interrogation of nuclear material, understanding the outgoing radiation spectrum is crucial. For low burnup fuels, the ^17,18O(α,n) reactions have been identified as a dominant source of neutrons. In the energy range of the α-decay of actinide elements, little data are available for these reactions, and it has been highlighted as a focus for experimental efforts. Existing data for the ¹⁸O(α,n)²¹Ne reaction are limited, with no partial cross section or neutron angular distribution data available. Therefore, a high-resolution measurement of this reaction was performed at the University of Notre Dame over the range E_α = 2-8 MeV, to extract partial and total cross sections. Deuterated scintillator detectors were used for neutron spectroscopy, analyzed via the spectrum unfolding technique. In addition, 2 HPGe detectors were used to detect secondary γ rays. Partial cross sections and angular distributions and SCALE neutron source calculations using these new data will be presented. Development of a new deuterated array at LLNL will also be presented.