Constraints on Exotic Heavily Ionizing Particles from the Geological Abundance of Fullerenes

The C_{60} molecule exhibits a remarkable stability and inertness that leads to its survival in ancient carbonaceous rocks initially subject to the high temperatures requisite for its formation. Elementary particles having very high electronic stopping powers can similarly form C_{60} and higher fullerenes in their wake. Combined, these two features point at the possibility of using the C_{60} presence (or absence) in selected bulk geological samples as a new type of solid-state nuclear track detector, with applications in astro-particle physics.Comment: Final version (few modifications). Phys. Rev. Lett. (in press). 4 pages LaTeX, 1 eps figure embedde