Physics-based modeling of cosmogenic nuclides part II – Key aspects of in-situ cosmogenic nuclide production

• Cosmic-ray radiation field in atmosphere and upper crust simulated using MCNPX.
• Surface production rates are parameterized as functions of altitude and latitude.
• Angular distribution of production is found to differ from the standard cos2.3(Θ).
• New form of shielding correction to account for near-horizontal particles presented.
• Subsurface production rate profiles are investigated.

Characteristics of the spallogenic component of nuclide production are investigated through the use of a physics-based model. Calculated production rates for commonly used nuclides indicate differences in scaling up to 15% at very high altitude. Angular distribution of nuclide forming particles suggests the current method of shielding correction, which is neither altitude nor latitude dependent, can be improved on. Subsurface production profiles suggest that erosion corrections should be performed with non-constant attenuation lengths. Results are parameterized for easy application.