Neutron flux and 10Be production rate as a function of geomagnetic latitude were investigated using both the recently developed Monte Carlo N Particle eXtend (MCNPX) code and the existing MCNP/LAHET code system. It has traditionally proved difficult to obtain neutron flux values close to actual measurements because of limitations inherent in the codes, and the lack of good quality measurements. For this study, we compared numerical simulations of neutron flux and 10Be production in water targets as a function of geomagnetic latitude with Southern Hemisphere data generated by I. Graham and co-workers during 1998-2001. Preliminary calculations for neutron fluxes at various geomagnetic latitudes at near surface sea level are consistent with the measured values, assuming a low effective primary proton flux of 2.6~3.25 p/cm2/s. These values are lower than those associated with long term exposure of meteorites in space or in deep lunar drill cores (4~5 p/cm2/s), and could be due to the strong solar modulation effect during period of neutron flux measurements. The good agreement between the numerical simulation results and the measured data is positive affirmation of the usefulness of the MCNPX code, and gives promise of future successful application along similar lines. The presentation will include details of the MCNPX calculations involved in both neutron flux and 10Be production rate simulation, and also a comparison of the MCNPX and MCNP/LAHET code results on the same dataset.
See more of Poster Session II
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)