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Search for neutron dark decay: n → χ + e⁺e⁻

Sun, X. and Adamek, E. and Allgeier, B. and Blatnik, M. and Bowles, T. J. and Broussard, L. J. and Brown, M. A.-P. and Carr, R. and Clayton, S. and Cude-Woods, C. and Currie, S. and Dees, E. B. and Ding, X. and Filippone, B. W. and García, A. and Geltenbort, P. and Hasan, S. and Hickerson, K. P. and Hoagland, J. and Hong, R. and Hogan, G. E. and Holley, A. T. and Ito, T. M. and Kneckt, A. and Liu, C.-Y. and Liu, J. and Makela, M. and Mammei, R. and Martin, J. W. and Melconian, D. and Mendenhall, M. P. and Moore, S. D. and Morris, C. L. and Nepal, S. and Nouri, N. and Pattie, R. W. and Galván, A. P. and Phillips II, D. G. and Picker, R. and Pitt, M. L. and Plaster, B. and Ramsey, J. C. and Rios, R. and Salvat, D. J. and Saunders, A. and Sondheim, W. and Sjue, S. and Slutsky, S. and Swank, C. and Swift, G. and Tatar, E. and Vogelaar, R. B. and VornDick, B. and Wanchun, W. and Wang, Z. and Wexler, J. and Womack, T. and Wrede, C. and Young, A. R. and Zeck, B. A. (2019) Search for neutron dark decay: n → χ + e⁺e⁻. EPJ Web of Conferences, 219 . Art. No. 05008. ISSN 2100-014X.

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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⁻ + ν̅_e decays. The summed kinetic energy (E_(e⁺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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Sun, X.0000-0001-8817-4643
Filippone, B. W.0000-0002-2618-2688
Hickerson, K. P.0000-0001-7647-119X
Ito, T. M.0000-0003-3494-6796
Additional Information:© 2020 The Authors, published by EDP Sciences. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0 ( Published online 13 December 2019. his work is supported in part by the US Department of Energy, Office of Nuclear Physics (DE-FG02-08ER41557, DESC0014622, DE-FG02-97ER41042) and the National Science Foundation (1002814, 1005233, 1205977, 1306997, 1307426, 1506459, and 1615153). We gratefully acknowledge the support of the LDRD program (20110043DR), the AOT division of the Los Alamos National Laboratory, and helpful discussions with B. Grinstein.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-08ER41557
Department of Energy (DOE)DESC0014622
Department of Energy (DOE)DE-FG02-97ER41042
Los Alamos National Laboratory20110043DR
Record Number:CaltechAUTHORS:20200309-123412503
Persistent URL:
Official Citation:Search for neutron dark decay: n → χ + e+e−. X. Sun, E. Adamek, B. Allgeier, M. Blatnik, T.J. Bowles, L.J. Broussard, M.A.-P. Brown, R. Carr, S. Clayton, C. Cude-Woods, S. Currie, E.B. Dees, X. Ding, B.W. Filippone, A. García, P. Geltenbort, S. Hasan, K.P. Hickerson, J. Hoagland, R. Hong, G.E. Hogan, A.T. Holley, T.M. Ito, A. Kneckt, C.-Y. Liu, J. Liu, M. Makela, R. Mammei, J.W. Martin, D. Melconian, M.P. Mendenhall, S.D. Moore, C.L. Morris, S. Nepal, N. Nouri, R.W. Pattie, A.P. Galván, D.G. Phillips II, R. Picker, M.L. Pitt, B. Plaster, J.C. Ramsey, R. Rios, D.J. Salvat, A. Saunders, W. Sondheim, S. Sjue, S. Slutsky, C. Swank, G. Swift, E. Tatar, R.B. Vogelaar, B. VornDick, W. Wanchun, Z. Wang, J. Wexler, T. Womack, C. Wrede, A.R. Young and B.A. Zeck. EPJ Web Conf., 219 (2019) 05008; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101785
Deposited By: Tony Diaz
Deposited On:09 Mar 2020 22:56
Last Modified:09 Mar 2020 22:56

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