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Gonzalez FM, Fries EM, Cude-Woods C, Bailey T, Blatnik M, Broussard LJ, Callahan NB, Choi JH, Clayton SM, Currie SA, Dawid M, Dees EB, Filippone BW, Fox W, Geltenbort P, George E, Hayen L, Hickerson KP, Hoffbauer MA, Hoffman K, Holley AT, Ito TM, Komives A, Liu CY, Makela M, Morris CL, Musedinovic R, O'Shaughnessy C, Pattie RW, Ramsey J, Salvat DJ, Saunders A, Sharapov EI, Slutsky S, Su V, Sun X, Swank C, Tang Z, Uhrich W, Vanderwerp J, Walstrom P, Wang Z, Wei W, Young AR. Improved Neutron Lifetime Measurement with UCNτ. Phys Rev Lett 2021; 127:162501. [PMID: 34723594 DOI: 10.1103/physrevlett.127.162501] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
We report an improved measurement of the free neutron lifetime τ_{n} using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38×10^{6} surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ_{n} from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ_{n} measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ_{n}=877.75±0.28_{stat}+0.22/-0.16_{syst} s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.
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Affiliation(s)
- F M Gonzalez
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E M Fries
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - C Cude-Woods
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - T Bailey
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - M Blatnik
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - L J Broussard
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - N B Callahan
- Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - J H Choi
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - S M Clayton
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S A Currie
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M Dawid
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
| | - E B Dees
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - B W Filippone
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - W Fox
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
| | - P Geltenbort
- Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
| | - E George
- Tennessee Technological University, Cookeville, Tennessee 38505, USA
| | - L Hayen
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - K P Hickerson
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - M A Hoffbauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - K Hoffman
- Tennessee Technological University, Cookeville, Tennessee 38505, USA
| | - A T Holley
- Tennessee Technological University, Cookeville, Tennessee 38505, USA
| | - T M Ito
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A Komives
- DePauw University, Greencastle, Indiana 46135, USA
| | - C-Y Liu
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
| | - M Makela
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C L Morris
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R Musedinovic
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
| | - C O'Shaughnessy
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R W Pattie
- East Tennessee State University, Johnson City, Tennessee 37614, USA
| | - J Ramsey
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D J Salvat
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
| | - A Saunders
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E I Sharapov
- Joint Institute for Nuclear Research, 141980 Dubna, Russia
| | - S Slutsky
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - V Su
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - X Sun
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - C Swank
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - Z Tang
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - W Uhrich
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Vanderwerp
- Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
- Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA
| | - P Walstrom
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Z Wang
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - W Wei
- Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
| | - A R Young
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
- Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
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Plaster B, Adamek E, Allgeier B, Anaya J, Back H, Bagdasarova Y, Berguno D, Blatnik M, Boissevain J, Bowles T, Broussard L, Brown MP, Carr R, Clark D, Clayton S, Cude-Woods C, Currie S, Dees E, Ding X, Du S, Filippone B, García A, Geltenbort P, Hasan S, Hawari A, Hickerson K, Hill R, Hino M, Hoagland J, Hoedl S, Hogan G, Hona B, Hong R, Holley A, Ito T, Kawai T, Kirch K, Kitagaki S, Knecht A, Lamoreaux S, Liu CY, Liu J, Makela M, Mammei R, Martin J, Meier N, Melconian D, Mendenhall M, Moore S, Morris C, Mortensen R, Nepal S, Nouri N, Pattie R, Pérez Galván A, Phillips II D, Pichlmaier A, Picker R, Pitt M, Ramsey J, Rios R, Russell R, Sabourov K, Sallaska A, Salvat D, Saunders A, Schmid R, Seestrom S, Servicky C, Sharapov E, Sjue S, Slutsky S, Smith D, Sondheim W, Sun X, Swank C, Swift G, Tatar E, Teasdale W, Terai C, Tipton B, Utsuro M, Vogelaar R, VornDick B, Wang Z, Wehring B, Wexler J, Womack T, Wrede C, Xu Y, Yan H, Young A, Yuan J, Zeck B. Final results for the neutron β-asymmetry parameter A0 from the UCNA experiment. EPJ Web Conf 2019. [DOI: 10.1051/epjconf/201921904004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The UCNA experiment was designed to measure the neutron β-asymmetry parameter A0 using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7 T magnetic field, and then directed to a 1 T solenoidal electron spectrometer, where the decay electrons were detected in electron detector packages located on the two ends of the spectrometer. A value for A0 was then extracted from the asymmetry in the numbers of counts in the two detector packages. We summarize all of the results from the UCNA experiment, obtained during run periods in 2007, 2008–2009, 2010, and 2011–2013, which ultimately culminated in a 0.67% precision result for A0.
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Sun X, Adamek E, Allgeier B, Blatnik M, Bowles T, Broussard L, Brown MP, Carr R, Clayton S, Cude-Woods C, Currie S, Dees E, Ding X, Filippone B, García A, Geltenbort P, Hasan S, Hickerson K, Hoagland J, Hong R, Hogan G, Holley A, Ito T, Kneckt A, Liu CY, Liu J, Makela M, Mammei R, Martin J, Melconian D, Mendenhall M, Moore S, Morris C, Nepal S, Nouri N, Pattie R, Galván A, Phillips II D, Picker R, Pitt M, Plaster B, Ramsey J, Rios R, Salvat D, Saunders A, Sondheim W, Sjue S, Slutsky S, Swank C, Swift G, Tatar E, Vogelaar R, VornDick B, Wanchun W, Wang Z, Wexler J, Womack T, Wrede C, Young A, Zeck B. Search for neutron dark decay: n → χ + e+e−. EPJ Web Conf 2019. [DOI: 10.1051/epjconf/201921905008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e+e− pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel.
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