We deployed the Mobile Skipper Testing Apparatus $\sim 33\mathrm{m}$ away from the Compact Muon Solenoid collision point, the first skipper-CCD detector probing low-energy particles produced in high-energy collisions at the Large Hadron Collider. In this work, we search for beam-related events using data collected in 2024 during beam-on and beam-off periods. The dataset corresponds to integrated luminosities of $113.3{\mathrm{fb}}^{-1}$ and $1.54{\mathrm{nb}}^{-1}$ for the proton-proton and Pb-Pb collision periods, respectively. We report observed event rates in a model-independent framework across two ionization regions: $\le 20e^{-}$ and $>20e^{-}$. For the low-energy region, we perform a likelihood analysis to test the null hypothesis of no beam-correlated signal. We found no significant correlation during proton-proton and Pb-Pb collisions. For the high-energy region, we present the energy spectra for both collision periods and compare event rates for images with and without luminosity. We observe a slight increase in the event rate following the Pb-Pb collisions, coinciding with a rise in the single-electron rate, which will be investigated in future work. Using the low-energy proton-proton results, we place 95% confidence level constraints on the mass-millicharge parameter space of millicharged particles. Overall, the results in this work demonstrate the viability of skipper-CCD technology to explore new physics at high-energy colliders and motivate future searches with more massive detectors.

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• Hypothetical particle physics models
• Particle dark matter
• Particle detection signatures
• Particle interactions
• Relativistic heavy-ion collisions
• Dark matter detectors
• Hadron colliders
• Particle accelerators
• Particle detectors
• Solid-state detectors