Tests of the standard model from superallowed Fermi β-decay studies: The 74Rb β-decay

  • E.F. Zganjar
  • A. Piechaczek
  • G.C. Ball
  • P. Bricault
  • J.M. D'Auria
  • J.C. Hardy
  • D.F. Hodgson
  • V. Iacob
  • P. Klages
  • W.D. Kulp
  • J.R. Leslie
  • M. Lipoglavsek
  • J.A. Macdonald
  • H.-B. Mak
  • D.M. Moltz
  • G. Savard
  • J. von Schwarzenberg
  • C.E. Svensson
  • I.S. Towner
  • J.L. Wood

Abstract:

Precise measurements of the intensities of superallowed Fermi 0+ → 0+β-decays have provided a powerful test of the CVC hypothesis at the level of 3×10-4 and also led to a result in disagreement with unitarity for the CKM matrix at the 98% confidence level. It is essential to address possible trivial explanations for the apparent non-unitarity such as uncertainties in the isospin symmetry-breaking corrections. We have carefully studied the 74Rb →74Kr β-decay in order to measure the non-analog β-decay branching to the 0+ state at 508 keV in 74Kr. We have determined that this branching is < 3×10-4, far smaller than any published theoretical estimate. We also show that high-precision, complete spectroscopy, measuring the major β-branches to excited 0+ and 1+ states, must be performed if one is to obtain a meaningful branching ratio to the excited 0+ state and concomitantly deal, in a substantial way, with the possibility of β feeding to an array of 1+ states.

PACS. 21.10.-k Properties of nuclei; nuclear energy levels – 23.40.-s Beta decay; double beta decay; electron and muon capture – 27.50.+e 59 ⩽ A ⩽ 89 

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2002

Authors and Affiliations

  • E.F. Zganjar
    • 1
  • A. Piechaczek
    • 1
  • G.C. Ball
    • 2
  • P. Bricault
    • 2
  • J.M. D'Auria
    • 3
  • J.C. Hardy
    • 4
  • D.F. Hodgson
    • 5
  • V. Iacob
    • 4
  • P. Klages
    • 6
  • W.D. Kulp
    • 7
  • J.R. Leslie
    • 8
  • M. Lipoglavsek
    • 9
  • J.A. Macdonald
    • 2
  • H.-B. Mak
    • 8
  • D.M. Moltz
    • 10
  • G. Savard
    • 11
  • J. von Schwarzenberg
    • 7
  • C.E. Svensson
    • 12
  • I.S. Towner
    • 8
  • J.L. Wood
    • 7
  1. 1.Louisiana State University, Baton Rouge, LA 70803-4001, USAUS
  2. 2.TRIUMF, Vancouver, B.C., V6T 2A3 CanadaCA
  3. 3.Simon Fraser University, Burnaby, B.C., V5A 1S6 CanadaCA
  4. 4.Texas A&M University, College Station, TX 77843, USAUS
  5. 5.University of Surrey, Guildford, Surrey, GU2 7XH UKGB
  6. 6.McMaster University, Hamilton, Ontario L8S 4L8 CanadaCA
  7. 7.Georgia Institute of Technology, Atlanta, GA 30332, USAUS
  8. 8.Queens University, Kingston, Ontario, K7L 3N6 CanadaCA
  9. 9.Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA and J. Stefan Institute, 1000 Ljubljana, SloveniaUS
  10. 10.Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USAUS
  11. 11.Argonne National Laboratory, Argonne, IL 60439, USAUS
  12. 12.University of Guelph, Guelph, Ontario, N1G 2W1 CanadaCA

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