title: High-Precision Half-Life Measurements for the Superallowed β^{+} Emitter ^{10}C: Implications for Weak Scalar Currents.
abstract: Precision measurements of superallowed Fermi β-decay transitions, particularly for the lightest superallowed emitters ^{10}C and ^{14}O, set stringent limits on possible scalar current contributions to the weak interaction. In the present work, a discrepancy between recent measurements of the ^{10}C half-life is addressed through two high-precision half-life measurements, via γ-ray photopeak and β counting, that yield consistent results for the ^{10}C half-life of T_{1/2}=19.2969±0.0074  s and T_{1/2}=19.3009±0.0017  s, respectively. The latter is the most precise superallowed β-decay half-life measurement reported to date and the first to achieve a relative precision below 10^{-4}. A fit to the world superallowed β-decay data including the ^{10}C half-life measurements reported here yields b_{F}=-0.0018±0.0021 (68% C.L.) for the Fierz interference term and C_{S}/C_{V}=+0.0009±0.0011 for the ratio of the weak scalar to vector couplings assuming left-handed neutrinos.
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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authors.initials: MR
authors.lastname: Dunlop
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: C E
authors.initials: CE
authors.lastname: Svensson
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.initials: GC
authors.lastname: Ball
authors.affiliation: GANIL, CEA/DRF-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen, France.
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authors.initials: GF
authors.lastname: Grinyer
authors.affiliation: Department of Physics, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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authors.initials: JR
authors.lastname: Leslie
authors.affiliation: Department of Chemistry, Simon Fraser University, Burnaby, British Colombia V5A 1S6, Canada.
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authors.lastname: Andreoiu
authors.affiliation: Department of Astronomy and Physics, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada.
authors.forename: R A E
authors.initials: RA
authors.lastname: Austin
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.lastname: Ballast
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.initials: PC
authors.lastname: Bender
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Bildstein
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Diaz Varela
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Dunlop
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: A B
authors.initials: AB
authors.lastname: Garnsworthy
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: P E
authors.initials: PE
authors.lastname: Garrett
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.lastname: Hackman
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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authors.lastname: Hadinia
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: D S
authors.initials: DS
authors.lastname: Jamieson
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: A T
authors.initials: AT
authors.lastname: Laffoley
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: A D
authors.initials: AD
authors.lastname: MacLean
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.initials: DM
authors.lastname: Miller
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.initials: WJ
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authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
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authors.lastname: Park
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: A J
authors.initials: AJ
authors.lastname: Radich
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: M M
authors.initials: MM
authors.lastname: Rajabali
authors.affiliation: Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: E T
authors.initials: ET
authors.lastname: Rand
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Unsworth
authors.affiliation: Department of Astronomy and Physics, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Valencik
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Wang
authors.affiliation: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Zganjar