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Published July 13, 2018 | Published + Submitted
Journal Article Open

Search for the Neutron Decay n → X + γ, Where X is a Dark Matter Particle


Fornal and Grinstein recently proposed that the discrepancy between two different methods of neutron lifetime measurements, the beam and bottle methods, can be explained by a previously unobserved dark matter decay mode, n → X + γ. We perform a search for this decay mode over the allowed range of energies of the monoenergetic γray for X to be dark matter. A Compton-suppressed high-purity germanium detector is used to identify γrays from neutron decay in a nickel-phosphorous-coated stainless-steel bottle. A combination of Monte Carlo and radioactive source calibrations is used to determine the absolute efficiency for detecting γ rays arising from the dark matter decay mode. We exclude the possibility of a sufficiently strong branch to explain the lifetime discrepancy with 97% confidence.

Additional Information

© 2018 American Physical Society. (Received 5 February 2018; revised manuscript received 1 May 2018; published 11 July 2018) This work was supported by the Los Alamos Laboratory Directed Research and Development (LDRD) office (Grant No. 20140568DR), the LDRD Program of Oak Ridge National Laboratory, managed by UT-Battelle, Limited Liability Corporation (LLC) (Grant No. 8215), the National Science Foundation (Grants No. 130692, No. 1307426, No. 161454, No. 1506459, and No. 1553861), the Indiana University (IU) Center for Space Time Symmetries (IUCSS), and United States Department of Energy (U.S. DOE) Low Energy Nuclear Physics (Grants No. DE-FG02-97ER41042, No. DE-SC0014622, and No. DE-AC05-00OR22725). The authors would like to thank the staff of Los Alamos Neutron Science Center (LANSCE) for their diligent efforts to develop the diagnostics and new techniques required to provide the proton beam for this experiment.

Attached Files

Published - PhysRevLett.121.022505.pdf

Submitted - 1802.01595


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August 19, 2023
October 18, 2023