Year: 1993
Type: article
Abstract: To solve the controversial issue concerning the possible existence of a 17 keV neutrino with a 1% admixture in nuclear $\ensuremath{\beta}$ decay, we searched directly for any evidence of a production-threshold effect. The $^{63}\mathrm{Ni}$ $\ensuremath{\beta}$ 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 ${|U|}^{2}=[\ensuremath{-}0.011\ifmmode\pm\else\textpm\fi{}0.033(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.030(\mathrm{syst})]%$, 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.
Authors: 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
Institution: High Energy Accelerator Research Organization
Language: English
Topic: Neutrino Physics Research
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Los Alamos National Laboratory
OpenAlex ID: W1985452071