Volcanic rocks can help track cosmic rays over 40,000 years
Scientists have found a creative way to track cosmic rays hitting Earth over the past 40,000 years, using volcanic rocks from France as natural "detectors."
This approach could provide a time-resolved (chronosequence) record of cosmic-ray activity over ~40,000 years that complements existing methods.
How does the method work?
Cosmic-ray muons interacting in olivine can induce nuclear recoils (via spallation or capture), and those recoiling nuclei leave short damage tracks in the crystals found in the volcanic xenoliths.
By looking at samples from different eruptions (which are already well-dated), researchers can see how the number of tracks changes with time.
If the pattern shifts, it means something changed in our cosmic environment.
What does it mean for our understanding of cosmic rays?
This method could detect spikes in cosmic rays associated with events like the Laschamp geomagnetic excursion, and could be sensitive to contributions from nearby supernovae in favorable scenarios.
It opens up new ways to study how space weather has changed through history and helps scientists understand what's been happening above our heads for ages.