Determination of the neutron lifetime using magnetically trapped neutrons

S. N. Dzhosyuk, A. Copete, J. M. Doyle, L. Yang, K. J. Coakley, R. Golub, E. Korobkina, T. Kreft, S. K. Lamoreaux, A. K. Thompson, G. L. Yang, P. R. Huffman

Research output: Contribution to journalArticlepeer-review


We report progress on an experiment to measure the neutron lifetime using magnetically trapped neutrons. Neutrons are loaded into a 1.1 T deep super-conducting Ioffe-type trap by scattering 0.89 nm neutrons in isotopically pure superfluid 4He. Neutron decays are detected in real time using the scintillation light produced in the helium by the beta-decay electrons. The measured trap lifetime at a helium temperature of 300 mK and with no ameliorative magnetic ramping is substantially shorter than the free neutron lifetime. This is attributed to the presence of neutrons with energies higher than the magnetic potential of the trap. Magnetic field ramping is implemented to eliminate these neutrons, resulting in an 833-63+74 trap lifetime, consistent with the currently accepted value of the free neutron lifetime.

Original languageEnglish (US)
Pages (from-to)339-343
Number of pages5
JournalJournal of Research of the National Institute of Standards and Technology
Issue number4
StatePublished - 2005
Externally publishedYes


  • Magnetic trapping
  • Neutron lifetime
  • Superthermal neutron production
  • Ultracold neutrons

ASJC Scopus subject areas

  • Engineering(all)


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