Analysis of bimodality in histograms formed from GALLEX and GNO solar neutrino data

Abstract

A histogram display of the solar neutrino capture-rate measurements made by the GALLEX experiment appears to be bimodal, but that of the follow-on GNO experiment does not. To assess the significance of these results, we introduce a "bimodality index" based on the probability-transform procedure. This confirms that the GALLEX measurements are indeed bimodal (at the 99.98 percent confidence level), and that the GNO measurements are not. Tracking the bimodality index as a function of time shows that the strongest contribution to bimodality comes from runs 42 to 62, i.e. from the time interval 1995.1 to 1996.9. The bimodality index for the first half (runs 1 through 33) is 2.56, whereas that for the second half (runs 33 through 65) is 7.05. Power-spectrum analysis shows a similar distinction: the peaks in the power spectrum formed from the second half are stronger than those in the power spectrum formed from the first half, suggesting that bimodality and rotational modulation are related.

arXiv comment14 pages, 8 figures

References in corpus (6)

• GNO Solar Neutrino Observations: Results for GNOI
• Complete results for five years of GNO solar neutrino observations
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• Comparative Analysis of GALLEX-GNO Solar Neutrino Data and SOHO/MDI Helioseismology Data; Further Evidence for Rotational Modulation of the Solar Neutrino Flux
• Comparative analysis of Gallex and GNO solar neutrino data
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Cited by in corpus (3)

• Combined analysis of solar neutrino and solar irradiance data: further evidence for variability of the solar neutrino flux and its implications concerning the solar core
• Evidence for R-Mode Oscillations in Super-Kamiokande Solar Neutrino Data
• Re-Examination of Possible Bimodality of GALLEX Solar Neutrino Data