Exploring Current Constraints on Antineutrino Production by 241Pu and Paths Towards the Precision Reactor Flux Era*

Nuclear reactors produce thermal energy from the fission of heavy nuclides in the reactor's fuel, such as ²³⁵U, ²³⁸U, ²³⁹Pu,  ²⁴¹Pu, and ²⁴⁰Pu. Each of these nuclides has its own decay chain, which produces beta particles, gamma rays, and antineutrinos. It is well-known the existence of discrepancies between existing reactor antineutrino detector data and theoretical predictions, which creates the need for further investigation. In this context, we have combined data of several experiments based at highly ²³⁵U enriched reactor cores (HEU) with conventional low-enriched cores (LEU) and performed global fits on them. These allowed us to explore new bounds to antineutrino production on the sub-dominant fission isotope of ²⁴¹Pu, which resulted in an IBD yield of σ₂₄₁ = 8.16 ± 3.47 cm2/fission, a value (135 ± 58)% that of current beta conversion models. Furthermore, we considered hypothetical neutrino measurements at HEU, LEU, mixed-oxide, and fast reactor facilities to conjecture on their limits of future IBD yield measurements and what knowledge we hope to obtain with them. We also suggest possible arrangements to maximize our understanding and testing of the current theoretical predictions.