Natural Radiocarbon from Cosmic Radiation

Abstract

${\mathrm{C}}^{14}$ produced by the ${\mathrm{N}}^{14}\mathrm{}(n,p)\mathrm{}$ reaction of cosmic-ray neutrons has been detected and identified. The ${\mathrm{C}}^{14}$ concentration of biological methane was enriched by factors of up to 260-fold by thermal diffusion to raise the activity to convenient levels for counting. The pure methane was used as the filling gas in large Geiger-Müller counters.