No 17 keV neutrino: Admixture < 0.073% (95% C.L.)

T. Ohshima, H. Sakamoto, T. Sato, J. Shirai, T. Tsukamoto, Y. Sugaya, K. Takahashi, T. Suzuki, C. Rosenfeld, S. Wilson, K. Ueno, Y. Yonezawa, H. Kawakami, S. Kato, S. Shibata, K. Ukai

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


To solve the controversial issue concerning the possible existence of a 17 keV neutrino with a 1% admixture in nuclear β decay, we searched directly for any evidence of a production-threshold effect. The Ni63 β spectrum was measured with a magnetic spectrometer, with very high statistics along with a fine energy scan over a narrow energy region around the expected threshold. The obtained mixing strength was |U|2=[-0.011±0.033(stat)±0.030(syst)]%, very consistent with zero, and decisively excluding the existence of a 17 keV neutrino admixing at the 1% level with the electron neutrino. The corresponding upper limit was set at |U|2<0.073% (95% C.L.). A new limit was also obtained for a wider mass range: |U|2<0.15% (95% C.L.) for 10.5 to 25.0 keV neutrinos.

Original languageEnglish
Pages (from-to)4840-4856
Number of pages17
JournalPhysical Review D
Issue number11
Publication statusPublished - 1993

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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