Progress on Minimizing Laser Pointing Fluctuations in MAGIS-100 via Structural Analysis

MAGIS-100 is a 100-m-baseline atom interferometer under construction at Fermilab, designed for precision quantum sensing and searches for new physics. To ensure long-term stability and avoid drift associated with active stabilization systems, the experiment prioritizes passive noise suppression. A dominant technical challenge arises from vibrations of the retro-reflecting mirror, which is mounted on a side wall and mechanically coupled to seismic and structural noise. These vibrations introduce both angular pointing fluctuations of the interferometer laser beam and mirror velocity noise. The latter produces Doppler shifts that appear as detuning noise, directly impacting how the atoms interact with the laser fields. We investigate passive mitigation of these effects through finite-element structural analysis of the mirror mount using ANSYS. The model is used to identify dominant vibrational modes and coupling pathways, with particular emphasis on the 50 - 500Hz frequency band where environmental noise is strongest. Guided by these simulations, we optimize the mount geometry and stiffness to shift resonances and suppress vibration transmission to the optical element. The optimized designs demonstrate an order-of-magnitude reduction in simulated angular and velocity noise relative to initial configurations within the targeted frequency band. Ongoing work includes constructing a comparison structure at Northwestern University to benchmark the simulations and inform future implementation in MAGIS-100.