Identifying, quantifying, and mitigating background with the time-resolved x-ray diffraction platform at the National Ignition Facility.

The time-resolved x-ray diffraction platform at the National Ignition Facility (NIF) fields electronic sensors closer to the exploding laser-driven target than any other NIF diagnostic in order to directly detect diffracted x rays from highly compressed materials. We document strategies to characterize and mitigate the unacceptably high background signals observed in this geometry. We specifically assess the possible effects of electromagnetic pulse, x-ray fluorescence, hot electrons, and sensor-specific non-x-ray artifacts. Significant background reduction is achieved by strategic shielding.