He and Ne ages of large presolar silicon carbide grains: Solving the recoil problem

TL;DR

This paper refines age determination methods for presolar silicon carbide grains by addressing recoil correction issues, revealing ages mostly under 200 million years, and discusses extending these methods to smaller grains.

Contribution

It introduces an improved recoil correction procedure for large presolar SiC grains and applies it to determine their He and Ne ages, enhancing age estimation accuracy.

Findings

Most grains are less than 200 Myr old.

Ages range from near zero to about 850 Myr.

Method can potentially be extended to smaller grains.

Abstract

Knowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of micrometer) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC "Jumbo" grains that range from close to zero to ~850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic rays.