Monte Carlo simulations of low-energy cosmogenic neutron fluxes near the bottom of cliff faces

Cosmogenic radionuclide analysis for determining exposure ages and erosion rates is becoming more extensively utilized. Due to the complexity of the neutron absorption production avenue, the interpretation of 36Cl data is a complex problem, particularly for non-trivial landform geometries. This work provides a numerical, Monte Carlo simulation analysis of variations in in situ cosmogenic 36Cl production rate near the bottom of vertical cliffs. It is found that in comparison with production at height (more than a thermal neutron mean free path length in air) the production rate in the cliff face increases with decreasing height, but within a thermal neutron mean free path length in rock near the bottom of the cliff, the production rate exhibits a sharp decrease.