Exploring Current Constraints on Antineutrino Production by $^{241}$Pu and Paths Towards the Precision Reactor Flux Era

Abstract

By performing global fits to inverse beta decay (IBD) yield measurements from existing neutrino experiments based at highly 235 U enriched reactor cores and conventional low-enriched cores, we explore current direct bounds on neutrino production by the sub-dominant fission isotope 241 Pu. For this nuclide, we determine an IBD yield of σ241 = 8.16 ± 3.47 cm 2 /fission, a value (135 ± 58)% that of current beta conversion models. This constraint is shown to derive from the non-linear relationship between burn-in of 241 Pu and 239 Pu in conventional reactor fuel. By considering new hypothetical neutrino measurements at high-enriched, low-enriched, mixed-oxide, and fast reactor facilities, we investigate the feasible limits of future knowledge of IBD yields for 235 U, 238 U, 239 Pu, 241 Pu, and 240 Pu. We find that first direct measurement of the 240 Pu IBD yield can be performed at plutonium-burning fast reactors, while a suite of correlated measurements at multiple reactor types can achieve a precision in direct 238 U, 239 Pu, and 241 Pu yield knowledge that meets or exceeds that of current theoretical predictions.