Abstract
Our knowledge of the possible existence in nature of stable exotic particles depends solely upon experimental observation. Using a sensitive laser spectroscopy technique, we searched for a doubly charged particle accompanied by two electrons as an anomalously heavy isotope of helium in the Earth’s atmosphere. The concentration of noble-gas-like atoms in the atmosphere and the subsequent very large depletion of the light isotopes allow stringent upper limits to be set on the abundance: per atom in the solar system over the mass range of 20–10 000 amu.
- Received 18 February 2003
DOI:https://doi.org/10.1103/PhysRevLett.92.022501
©2004 American Physical Society