NASA GSFC & CRESST/USRA
Current and Future Measurements of Ultra-Heavy Galactic Cosmic Rays.
The gold in your jewelry, the silver and tin in the solder of your electronics and the platinum in your vehicle’s catalytic converter all were most likely synthesized in the heart of a supernova explosion. Normal stellar nucleosynthesis fusion processes can explain the creation of matter through atomic number Z=26 (Iron), but not heavier elements. These ultra-heavy elements are thought to be produced via neutron bombardment of atoms during the violent supernova death of a star. These ultra-heavy elements are of particular interest to scientists who study galactic cosmic rays (GCRs). GCRs are particles that have been accelerated by astrophysical processes to MeV, GeV and even higher energies. Despite first being discovered over 100 years ago, the origin and acceleration mechanism for these particles is still not fully understood. Ultra-heavy cosmic-ray particles are of particular interest as they can provide insight to understanding the origin and acceleration process of GCRs. Measuring ultra-heavy GCRS is a challenge due to their low flux and high interaction cross section, requiring extremely large detectors flown on balloons and in space. In this talk I will discuss how past and recent ultra-heavy cosmic ray measurements have shaped our understanding of the cosmic-ray source and acceleration process and what we hope to learn from future measurements. I will present results on the abundances of ultra-heavy cosmic rays, with particular focus on recent measurements in the charge range of 26 ≤ Z ≤ 40 from the SuperTIGER Antarctic balloon flight. I will also review the current status of active missions to measure ultra-heavy cosmic rays and discuss future possibilities.