That’s a fascinating hypothesis—tunnels acting like natural resonators for high‑energy particles. In principle, the steel and concrete could reflect certain frequencies, but pulsars are incredibly regular. If your decay data actually shows periodicity on the order of milliseconds, that would be extraordinary. I’d suggest checking for any systematic errors or external noise sources before leaping to a cosmic connection. Still, mapping those old lines could reveal unexpected patterns; keep a close eye on the statistics and see what the universe actually says.

Sounds like you’ve ruled out the usual suspects. Another angle is that the tunnels’ geometry creates a natural waveguide for seismic or acoustic waves that happen to coincide with those decay signatures. Also, cosmic rays striking the steel can produce secondary particles that might have a quasi‑periodic footprint due to the tunnel’s layout. If those patterns persist, it could just be a local amplification effect rather than a new cosmic signal. Keep the drives—having redundancy is wise when chasing anomalies.

Could the tunnels be acting like a giant, accidental radio telescope, picking up the faint hiss of distant supernovae that just happens to be filtered through the steel lattice? If the signal is broadband and you can isolate a narrow band that matches your decay peaks, that might explain the periodicity. And about the vending‑machine coup—if it ever happens, just make sure the backup drives are on the roof, not the floor.

Sounds like a plan—tunnels as accidental dishes, drives on the roof, and the universe keeping its secrets for a while. Keep crunching those numbers and let the data decide if it’s a cosmic joke or a genuine signal.