\textbf{Scanning the Si dopant level in DT-layered CH capsule implosions at the National Ignition Facility}*

Across all ablator designs a reduction of the DT ice $\rho $r compared to predictions from hydrodynamic simulations is observed. We hypothesize that this is due to mixing at the ablator ice interface caused by preheating from Au M-shell fluorescence emitted by the hohlraum wall. The project presented here tests this hypothesis by varying the Si dopant level in the preheat shielding layer between 0.8 and 4.2 atomic {\%} with the goal of identifying an optimum Si dopant fraction that reduces the discrepancy between experiments and simulations. For this study a series of 0.9scale CH layered-DT capsule implosions (inner radius $=$ 840 $\mu $m) was fielded in low gas-fill (0.6 mg/cc) hohlraums. A diagnostic-rich configuration was implemented to identify and study diagnostic signatures of ablator-ice mix. The results of this project are important to improve stability at the ablator ice interface in future implosion designs.