Novel emulators for fission event generators

Fission event generators, such as the LANL-developed code CGMF, are being used with increasing frequency in the analysis and interpretation of experimental measurements. These calculations begin with information on fission fragment initial conditions in mass, charge, kinetic energy, spin, and parity, and follow the de-excitation of the fission fragments through prompt neutron and γ-ray emission, conserving energy, momentum, and angular momentum throughout the process. For each fission event, information about the fragment initial conditions are recorded, along with the multiplicity of the emitted neutrons and γ rays, and their energies and directions. The breadth of the observables that are calculated along with the multiple physics models that are included in the complete calculation require the development of a novel emulator to speed up this type of calculation. Here we discuss the construction of an emulator for CGMF that takes as input the fission fragment initial conditions and uses a combination of classifiers and probabilistic mixture density networks to emulate the full decay. The speedup gained from this type of emulator opens the door to consistent optimization of all prompt fission observables.