title: Novel search for heavy nu mixing from the beta+ decay of 38mK confined in an atom trap.
abstract: A new technique, full neutrino momentum reconstruction, is used to set limits on the admixture of heavy neutrinos into the electron neutrino. We measure coincidences between nuclear recoils and positrons from the beta decay of trapped radioactive atoms and deduce the neutrino momentum. A search for peaks in the reconstructed recoil time-of-flight spectrum as a function of positron energy is performed. The admixture upper limits range from 4 x 10(-3) to 2 x 10(-2) and are the best direct limits for neutrinos (as opposed to antineutrinos) for the mass region of 0.7 to 3.5 MeV.
authors.affiliation: Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6. trin@triumf.ca
authors.forename: M
authors.initials: M
authors.lastname: Trinczek
authors.forename: A
authors.initials: A
authors.lastname: Gorelov
authors.forename: D
authors.initials: D
authors.lastname: Melconian
authors.forename: W P
authors.initials: WP
authors.lastname: Alford
authors.forename: D
authors.initials: D
authors.lastname: Asgeirsson
authors.forename: D
authors.initials: D
authors.lastname: Ashery
authors.forename: J A
authors.initials: JA
authors.lastname: Behr
authors.forename: P G
authors.initials: PG
authors.lastname: Bricault
authors.forename: J M
authors.initials: JM
authors.lastname: D'Auria
authors.forename: J
authors.initials: J
authors.lastname: Deutsch
authors.forename: J
authors.initials: J
authors.lastname: Dilling
authors.forename: M
authors.initials: M
authors.lastname: Dombsky
authors.forename: P
authors.initials: P
authors.lastname: Dubé
authors.forename: S
authors.initials: S
authors.lastname: Eaton
authors.forename: J
authors.initials: J
authors.lastname: Fingler
authors.forename: U
authors.initials: U
authors.lastname: Giesen
authors.forename: S
authors.initials: S
authors.lastname: Gu
authors.forename: O
authors.initials: O
authors.lastname: Häusser
authors.forename: K P
authors.initials: KP
authors.lastname: Jackson
authors.forename: B
authors.initials: B
authors.lastname: Lee
authors.forename: J H
authors.initials: JH
authors.lastname: Schmid
authors.forename: T J
authors.initials: TJ
authors.lastname: Stocki
authors.forename: T B
authors.initials: TB
authors.lastname: Swanson
authors.forename: W
authors.initials: W
authors.lastname: Wong