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Fenker B, Gorelov A, Melconian D, Behr JA, Anholm M, Ashery D, Behling RS, Cohen I, Craiciu I, Gwinner G, McNeil J, Mehlman M, Olchanski K, Shidling PD, Smale S, Warner CL. Precision Measurement of the β Asymmetry in Spin-Polarized ^{37}K Decay. Phys Rev Lett 2018; 120:062502. [PMID: 29481259 DOI: 10.1103/physrevlett.120.062502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 12/23/2017] [Indexed: 06/08/2023]
Abstract
Using Triumf's neutral atom trap, Trinat, for nuclear β decay, we have measured the β asymmetry with respect to the initial nuclear spin in ^{37}K to be A_{β}=-0.5707(13)_{syst}(13)_{stat}(5)_{pol}, a 0.3% measurement. This is the best relative accuracy of any β-asymmetry measurement in a nucleus or the neutron, and is in agreement with the standard model prediction -0.5706(7). We compare constraints on physics beyond the standard model with other β-decay measurements, and improve the value of V_{ud} measured in this mirror nucleus by a factor of 4.
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Affiliation(s)
- B Fenker
- Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, Texas 77843-3366, USA
- Department of Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, Texas 77843-4242, USA
| | - A Gorelov
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - D Melconian
- Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, Texas 77843-3366, USA
- Department of Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, Texas 77843-4242, USA
| | - J A Behr
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - M Anholm
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - D Ashery
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - R S Behling
- Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, Texas 77843-3366, USA
- Department of Chemistry, Texas A&M University, 3012 TAMU, College Station, Texas 77843-3012, USA
| | - I Cohen
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - I Craiciu
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - G Gwinner
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - J McNeil
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Mehlman
- Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, Texas 77843-3366, USA
- Department of Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, Texas 77843-4242, USA
| | - K Olchanski
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - P D Shidling
- Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, Texas 77843-3366, USA
| | - S Smale
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - C L Warner
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
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Roger T, Büscher J, Bastin B, Kirsebom OS, Raabe R, Alcorta M, Äystö J, Borge MJG, Carmona-Gallardo M, Cocolios TE, Cruz J, Dendooven P, Fraile LM, Fynbo HOU, Galaviz D, Gasques LR, Giri GS, Huyse M, Hyldegaard S, Jungmann K, Kruithof WL, Lantz M, Perea A, Riisager K, Saastamoinen A, Santra B, Shidling PD, Sohani M, Sørensen AJ, Tengblad O, Traykov E, van der Hoek DJ, Van Duppen P, Versolato OO, Wilschut HW. Precise determination of the unperturbed 8B neutrino spectrum. Phys Rev Lett 2012; 108:162502. [PMID: 22680713 DOI: 10.1103/physrevlett.108.162502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Indexed: 06/01/2023]
Abstract
A measurement of the final state distribution of the (8)B β decay, obtained by implanting a (8)B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyväskylä [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fits. Combined with the IGISOL data, this leads to an improvement of the overall errors and the extension of the neutrino spectrum at high energy. The new unperturbed neutrino spectrum represents a benchmark for future measurements of the solar neutrino flux as a function of energy.
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Affiliation(s)
- T Roger
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Belgium
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