[2107.02881]
L. Snyder, M. Anastasiou, N. S. Bowden, J. Bundgaard, R. J. Casperson, D. A. Cebra, T. Classen, D. H. Dongwi, N. Fotiades, J. Gearhart, V. Geppert-Kleinrath, U. Greife, C. Hagmann, M. Heffner, D. Hensle, D. Higgins, L. D. Isenhower, K. Kazkaz, A. Kemnitz, J. King, J. L. Klay, J. Latta, E. Leal-Cidoncha, W. Loveland, J. A. Magee, B. Manning, M. P. Mendenhall, M. Monterial, S. Mosby, D. Neudecker, C. Prokop, S. Sangiorgio, K. T. Schmitt, B. Seilhan, F. Tovesson, R. S. Towell, N. Walsh, T. S. Watson, L. Yao, W. Younes
The $^{239}$Pu(n,f)/$^{235}$U(n,f) cross-section ratio has been measured with the fission Time Projection Chamber (fissionTPC) from 100 keV to 100 MeV. The fissionTPC provides three-dimensional reconstruction of fission-fragment ionization profiles, allowing for a precise quantification of measurement uncertainties. The measurement was performed at the Los Alamos Neutron Science Center which provides a pulsed white source of neutrons. The data are recommended to be used as a cross-section ratio shape. A discussion of the status of the absolute normalization and comparisons to ENDF evaluations and previous measurements is included.