Accretion rate of extraterrestrial 41Ca in Antarctic snow samples

[摘要] Interplanetary Dust Particles (IDPs) are small grains, generally less than a few hundred micrometers in size. Their main source is the Asteroid Belt, located at 3 AU from the Sun, between Mars and Jupiter. During their flight from the Asteroid Belt to the Earth they are irradiated by galactic and solar cosmic rays (GCR and SCR), thus radionuclides are formed, like Ca-41 and Mn-53. Therefore, Ca-41 (T-1/2 = 1.03 x 10(5) yr) can be used as a key tracer to determine the accretion rate of IDPs onto the Earth because there are no significant terrestrial sources for this radionuclide. The first step of this study consisted to calculate the production rate of Ca-41 in IDPs accreted by the Earth during their travel from the Asteroid Belt. This production rate, used in accordance with the Ca-41/Ca-40 ratios that will be measured in snow samples from the Antarctica will be used to calculate the amount of extraterrestrial material accreted by the Earth per year. There challenges for this project are, at first, the much longer time for the flight needed by the IDPs to travel from the Asteroid Belt to the Earth in comparison with the Ca-41 half-life yields an early saturation for the Ca-41/Ca-40 ratio, and second, the importance of selecting the correct sampling site to avoid a high influx of natural Ca-40, preventing dilution of the Ca-41/Ca-40 ratio, the quantity measured by AMS. (C) 2015 Elsevier B.V. All rights reserved.

[发布日期] 2015-10-15

[效力级别]  Proceedings Paper

[关键词] AMS;Ca-41;Interplanetary dust