Production rates of Be-10, C-14, and Al-26 from terrestrial quartz were calculated for sea level and no geomagnetic fields using two numerical simulation codes and existing cross sections. This work is part of the international CRONUS project to get improved production systematics for terrestrial in situ cosmic-ray-produced cosmogenic nuclides. Production rates for these nuclides (in units of atoms/yr/g-quartz) ignoring muons were reported by Masarik and Reedy [EPSL, 1995] using the LAHET Code System (LCS) to be Be-10 (5.97), C-14 (18.6), and Al-26 (36.1). For this work, we used the same or similar cross sections but newer codes for calculating neutron fluxes, the latest version of LCS and the Monte Carlo N Particle eXtend (MCNPX) codes. Both codes have been used often for production rates of cosmogenic nuclides in meteorites and lunar samples. As before, the incident proton fluxes were normalized to an effective flux of galactic-cosmic-ray (GCR) protons as determined in the Apollo 15 deep drill core for each radionuclide. This lunar normalization is for the last few half-lives of each radionuclide and might not be representative for more recent time periods. The production rates with the newest versions of LCS and MCNPX are Be-10 (5.7 and 4.5), C-14 (18.7 and 19.0), and Al-26 (34.3 and 29.6), although there might have been some minor changes in some of the cross sections that we used. Other comparisons that we have done using several options in MCNPX and between LCS and MCNPX show that the codes can give slightly different rates. We are working on getting the best normalizations for these cosmogenic nuclides with these codes. We are also revising the cross sections used in these calculations (some of them were generated over 2 decades ago) using measured cross sections and measured activities in several natural and artificially-irradiated objects. Eventually, we hope to include new cross sections measured with neutrons and to use well-calibrated terrestrial samples, work that will be done over the nest few years by CRONUS participants.
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