title: Search for anomalously heavy isotopes of helium in the earth's atmosphere.
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 (3,4)He isotopes allow stringent upper limits to be set on the abundance: 10(-12)-10(-17) per atom in the solar system over the mass range of 20-10 000 amu.
authors.affiliation: Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: P
authors.initials: P
authors.lastname: Mueller
authors.forename: L-B
authors.initials: LB
authors.lastname: Wang
authors.forename: R J
authors.initials: RJ
authors.lastname: Holt
authors.forename: Z-T
authors.initials: ZT
authors.lastname: Lu
authors.forename: T P
authors.initials: TP
authors.lastname: O'Connor
authors.forename: J P
authors.initials: JP
authors.lastname: Schiffer