Exploring current constraints on antineutrino production by Pu241 and paths towards the precision reactor flux era

By performing global fits to inverse beta-decay (IBD) yield measurements from existing neutrino experiments based at highly 235U-enriched reactor cores and conventional low-enriched cores, we explore current direct bounds on neutrino production by the subdominant fission isotope 241Pu. For this nuclide, we determine an IBD yield of σ241 = 8.16 ± 3.47 cm2/fission, a value (135 ± 58)% that of current beta-conversion models. This constraint is shown to derive from the nonlinear relationship between the burn-in of 241Pu and 239Pu in conventional reactor fuel. By considering new hypothetical neutrino measurements at highly-enriched, low-enriched, mixed-oxide, and fast reactor facilities, we investigate the feasible limits of future knowledge of IBD yields for 235U, 238U, 239Pu, 241Pu, and 240Pu. We find that the first direct measurement of the 240Pu IBD yield can be performed at plutonium-burning fast reactors, while a suite of correlated measurements at multiple reactor types can achieve precision in direct 238U, 239Pu, and 241Pu yield knowledge that meets or exceeds that of current theoretical predictions.