Production of carbon 14 by cosmic‐ray neutrons

The rate of production of carbon 14 by cosmic‐ray neutrons is calculated by multigroup diffusion theory as a function of altitude, latitude, and time, and it is normalized to absolute cosmic‐ray neutron flux measurements. The global average production rate over the last ten solar cycles is found to be 2.50 ± 0.50 carbon 14 atoms per square centimeter per second. This value is compared with recent estimates of the decay rate of 1.8 ± 0.2 and 1.9 ± 0.2, and some of the possible implications are discussed.