  Analyses of neutrino measurements acquired by the Super-Kamiokande Neutrino
Observatory (SK, for the time interval 1996 - 2001) and of radon decay
measurements acquired by the Geological Survey of Israel (GSI, for the time
interval 2007 - 2017) yield remarkably consistent detections of the same
oscillation: frequency 9.43 +/- 0.04 year-1 (SK), 9.44 +/- 0.04 year-1 (GSI);
amplitude 6.8 +/- 1.7 % (SK), 7.0 +/- 1.0 % (GSI); phase 124 +/- 15 deg. (SK),
124 +/- 9 deg. (GSI). We briefly discuss possible hypotheses that may be
relevant to this experimental result.
