Kosmogenisk

Kosmogenisk refers to substances, isotopes, or processes produced by cosmic rays interacting with matter, either in space or on Earth. The term is used in geology, astroparticle physics, and archaeology to describe materials whose isotopic composition records exposure to cosmic radiation. Cosmogenic nuclides can accumulate in surface rocks, ice, sediments, meteorites, and lunar samples, providing information about exposure histories, shielding, and space weather.

Production occurs mainly by spallation reactions when high-energy protons and heavier cosmic-ray particles strike target nuclei, producing new isotopes. Fast neutrons from these interactions can be captured or induce further reactions. Other pathways involve muons and secondary particles. Notable cosmogenic nuclides include 14C, 10Be, 26Al, 36Cl, 32Si, 3He, and 21Ne. In the atmosphere, 14C is produced from 14N via neutron capture; in surface media, production rates depend on altitude, latitude, shielding, and solar activity.

Applications include exposure dating of surfaces such as rock faces, glacial moraines, and ice cores; reconstruction of erosion rates and past climate and ice-sheet dynamics; and measurements in meteorites to infer shielding depth and cosmic-ray history. In radiocarbon dating, the atmospheric 14C that is incorporated into living organisms originates from cosmogenic production.

Measurement typically uses accelerator mass spectrometry to detect rare cosmogenic isotopes at trace levels. Production-rate calibrations rely on models of cosmic-ray flux, which vary with latitude, altitude, and solar modulation. Limitations include complex irradiation histories and uncertainties in production constants. Kosmogenisk processes thus provide crucial tools for understanding both Earth history and the space environment.