Production of nucleogenic neon in the Earth from natural radioactive decay

Abstract

[1980] and Kyser and Rison [1982]. The present study also has shown that the nucleogenic 2•Ne production from the 24Mg(n,00 reaction is only about one-fifth the previous estimate. The contribution of nucleogenic 21Ne from the 24Mg(n,00 reaction is insignificant compared with nucleogenic 2•Ne production from 180(o•,n). Our estimate of the nucleogenic 2•Ne/radiogenic 4He production ratio both in the mantle and in the crust is 4.5 x 10 -8. This production ratio is quite consistent with nucleogenic 21Ne/radiogenic 4He ratios actually observed in crustal fluid samples ((4.6 + 0.8) x 10-8). The error in calculation of the nucleogenic neon production, resulting from a random statistical variation of the entry neutron yields and cross sections, is estimated to be less than 5%.

Nucleogenic production of Ne isotopes in Earth's crust and upper mantle induced by alpha particles from the decay of U and Th

“…Our approach is more stringent than that used by Hiinemohr [1989] and Yatsevich and Honda [1997] to calculate the Ne production in mean crust and mantle, since we rely on cross section data instead of thick-target yields. Hence, our approach is applicable to a wide field of target element compounds, since the calculations are independent of limiting assumptions on, e.g., stopping power ratios.…”

“…Since the stopping powers for pure elements differ from those for the actual chemical composition considered, a corresponding correction was necessary. This was done by assuming that the ratios of the stopping powers for different elements are independent of energy (for more details see, e.g., West [1979] and Yatsevich and Honda [1997]). In contrast, in our new approach the mass stopping power for the chemical compound is calculated directly and then folded with the excitation functions of the underlying nuclear reactions.…”

Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario

“…[23] The model assumes a uniform initial helium distribution within grains that was determined by Hunt [2000] using the 21 Ne-4 He method [Yatsevich and Honda, 1997] that between 60 and 87% of helium had been lost prior to till emplacement.…”

Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

“…We provide a comparison of nucleogenic production rates of neutrons, 21 Ne, and 39 Ar calculated in this study to select recent evaluations (Yatsevich and Honda, 1997;Leya and Wieler, 1999;Mei et al, 2010;Yokochi et al, 2012Yokochi et al, , 2014. Similar calculations were previously performed by Fabryka-Martin (1988); Andrews et al (1989Andrews et al ( , 1991; Lehmann et al (1993); Lehmann and Purtschert (1997).…”

“…In section 6 we present the results, including coefficients for production rate evaluation (6.3) and an estimate of the uncertainty in the calculated results (6.4). A discussion follows in section 7 where we compare our calculations with recent results (Yatsevich and Honda, 1997;Mei et al, 2010;Yokochi et al, 2012Yokochi et al, , 2014.1), calculate the nucleogenic neutron flux out of a rock (7.2), and discuss the geochemical implications (7.3). Concluding remarks follow in section 8.…”