First measurement of the neutron β asymmetry with ultracold neutrons

  • R. W. Pattie
  • , J. Anaya
  • , H. O. Back
  • , J. G. Boissevain
  • , T. J. Bowles
  • , L. J. Broussard
  • , R. Carr
  • , D. J. Clark
  • , S. Currie
  • , S. Du
  • , B. W. Filippone
  • , P. Geltenbort
  • , A. García
  • , A. Hawari
  • , K. P. Hickerson
  • , R. Hill
  • , M. Hino
  • , S. A. Hoedl
  • , G. E. Hogan
  • , A. T. Holley
  • T. M. Ito, T. Kawai, K. Kirch, S. Kitagaki, S. K. Lamoreaux, C. Y. Liu, J. Liu, M. Makela, R. R. Mammei, J. W. Martin, D. Melconian, N. Meier, M. P. Mendenhall, C. L. Morris, R. Mortensen, A. Pichlmaier, M. L. Pitt, B. Plaster, J. C. Ramsey, R. Rios, K. Sabourov, A. L. Sallaska, A. Saunders, R. Schmid, S. Seestrom, C. Servicky, S. K.L. Sjue, D. Smith, W. E. Sondheim, E. Tatar, W. Teasdale, C. Terai, B. Tipton, M. Utsuro, R. B. Vogelaar, B. W. Wehring, Y. P. Xu, A. R. Young, J. Yuan

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

We report the first measurement of an angular correlation parameter in neutron β decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for ∼30s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2×2π solenoidal spectrometer. We determine a value for the β-asymmetry parameter A0=-0.1138±0.0046±0.0021.

Original languageEnglish
Article number012301
JournalPhysical Review Letters
Volume102
Issue number1
DOIs
StatePublished - Jan 5 2009
Externally publishedYes

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