THE ORIGIN OF THE SPURIOUS 17KEV NEUTRINO SIGNAL OBSERVED IN S-35 BETA-DECAY
An exhaustive study has been made of the β spectrum of 35S, recorded with a Si(Li) detector. The object was to identify the origin of the significant distortion in the 35S β spectrum some 17keV below the end point, reported three years ago and interpreted then as evidence for a 17keV neutrino. A var...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
| Published: |
1994
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| Summary: | An exhaustive study has been made of the β spectrum of 35S, recorded with a Si(Li) detector. The object was to identify the origin of the significant distortion in the 35S β spectrum some 17keV below the end point, reported three years ago and interpreted then as evidence for a 17keV neutrino. A variety of different geometries were used and the collimation was also varied. Proton microprobe studies, yield of barium X-rays and source tilting have shown that the 35S sources, prepared by chemical adsorption of Ba35SO4, are clumped and locally thick, causing an energy loss ∼0.3 keV at 150 keV electron energy. The spectra are well fitted without any 17 keV neutrino admixture if this is taken into account; neglect of this additional energy loss mimics presence of a 17 keV neutrino and the mechanism giving rise to this mimicry is elucidated. The apparent evidence for a 17 keV neutrino in the 35S β spectrum arose primarily because the sources were assumed thin. Neglect of scattering effects and of a low energy pile-up correction also contributed to the misinterpretation. |
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