  Motivated by the theoretical hypotheses on the existence of heretofore
unobserved stable elementary particles and exotic nuclear states, we searched
for doubly-charged particles, as anomalously heavy isotopes of helium, in the
Earth's atmoshpere using a sensitive laser spectroscopy technique. The
concentration of noble-gas-like atoms in the atmosphere and the subsequent very
large depletion of the light He-3,4 isotopes allow us to set stringent limits
on th abundance: 10^-13 to 10^-17 per atom in the solar system, over the mass
range of 20 to 10,000 amu.
