Cosmogenic production rates and recoil loss effects in micrometeorites and interplanetary dust particles

<jats:title>Abstract</jats:title><jats:p>We present a purely physical model to determine cosmogenic production rates for noble gases and radionuclides in micrometeorites (<jats:styled-content style="fixed-case">MM</jats:styled-content>s) and interplanetary dust particles (<jats:styled-content style="fixed-case">IDP</jats:styled-content>s) by solar cosmic‐rays (<jats:styled-content style="fixed-case">SCR</jats:styled-content>) and galactic cosmic‐rays (<jats:styled-content style="fixed-case">GCR</jats:styled-content>) fully considering recoil loss effects. Our model is based on various nuclear model codes to calculate recoil cross sections, recoil ranges, and finally the percentages of the cosmogenic nuclides that are lost as a function of grain size, chemical composition of the grain, and the spectral distribution of the projectiles. The main advantage of our new model compared with earlier approaches is that we consider the entire <jats:styled-content style="fixed-case">SCR</jats:styled-content> particle spectrum up to 240 MeV and not only single energy points. Recoil losses for <jats:styled-content style="fixed-case">GCR</jats:styled-content>‐produced nuclides are assumed to be equal to recoil losses for <jats:styled-content style="fixed-case">SCR</jats:styled-content>‐produced nuclides. Combining the model predictions with Poynting‐Robertson orbital lifetimes, we calculate cosmic‐ray exposure ages for recently studied <jats:styled-content style="fixed-case">MM</jats:styled-content>s, cosmic spherules, and <jats:styled-content style="fixed-case">IDP</jats:styled-content>s. The ages for <jats:styled-content style="fixed-case">MM</jats:styled-content>s and the cosmic‐spherule are in the range <2.2–233 Ma, which corresponds, according to the Poynting‐Robertson drag, to orbital distances in the range 4.0–34 AU. For two <jats:styled-content style="fixed-case">IDP</jats:styled-content>s, we determine exposure ages of longer than 900 Ma, which corresponds to orbital distances larger than 150 AU. The orbital distance in the range 4–6 AU for one <jats:styled-content style="fixed-case">MM</jats:styled-content> and the cosmic spherule indicate an origin either in the asteroid belt or release from comets coming either from the Kuiper Belt or the Oort Cloud. Three of the studied <jats:styled-content style="fixed-case">MM</jats:styled-content>s have orbital distances in the range 23–34 AU, clearly indicating a cometary origin, either from short‐period comets from the Kuiper Belt or from the Oort Cloud. The two <jats:styled-content style="fixed-case">IDP</jats:styled-content>s have orbital distances of more than 150 AU, indicating an origin from Oort Cloud comets.</jats:p>