Neutron isotope production from radiogenic nuclides (2888U, 232Th, ...) in Earth crust rocks. How can their products be assessed given most common rock types and what are the results of such calculations.
Best regards.
Dear Rui Rosa
What do you mean by "Neutron Isotope" exactly? I suppose you mean 238U not 2888U. Also, 238U and 232Th are radioactive nuclides and not radiogenic nuclides, they are parents of two radioactive chains. A radiogenic nuclide is a nuclide that is produced by a process of radioactive decay.
Best Regards,
Dear Yehia H. Dawood:
Sorry I meant 238U. I refer to the nuclear transmutations produced in the rock matrix as a result of the decay of the radioactive nuclides (238U and 232Th etc and their progeny) through the agency of the alfa particles emitted by such radioactive chains.
Best regards
Dear Rui Rosa
Thanks for clarification. Several changes could be happened in the rock matrix and in the radioactive minerals in these rocks due to radiation including alpha particle emissions and alpha-recoil process. These include chemical and physical changes such as uranium-series diequilibrium in open system, metamictization, Radial fracturing in the radioactive minerals mostly due to thermal energy that is associated with radiation, radio haleos including the remarkable pleochroic halos in mica and amphibole mineral groups and also the discoloration in some minerals such as fluorite due to fluorine ion gap.
Best regards
Alpha particles from natural radionuclides are able to produce nuclear reactions with light elements. During the early stages of research on nuclear reactions (before the discovery of the neutron in 1932 and the design of the first cyclotron in 1931) , alpha particles were almost the only projectile available for nuclear reactions. Such reactions allowed to discover the neutron (9Be being the target) or the first artificial radionuclide 30P (with 27Al as target). But reactions of alphas producing radionuclides are very marginal in nature because (a) alphas efficiently loose their energy by ionisation and rapidly fall under the Coulomb threshold of reaction, (b) natural alphas cannot react with heavier elements, (c) many reactions produce stable nuclides.
Cosmic neutrons are much more efficient in producing radionuclides in the earth crust.
Dear Yehia H. Dawood, Dear François Tondeur:
Thanks for your explanations that clarify and fit well in the notions I had on this subect. I wonder what are the relative probabilities of the different nuclide outcomes from Alpha particles emitted by U and Th series (in secular equilibrium) - energy 2 through 8 MeV - in a rock with the average composition of the Earth crust. The most relevant targets will range from Li trough o Mg.
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