Re-Examination of Possible Bimodality of GALLEX Solar Neutrino Data

TL;DR

This paper investigates the bimodal distribution of GALLEX solar neutrino data, finding that the bimodality arises from different run durations, and shows that re-analyses lead to unimodal results, aligning with GNO data.

Contribution

It reveals that the bimodality in GALLEX data is due to run duration differences and demonstrates that re-analyses produce unimodal histograms consistent with GNO.

Findings

Bimodality in GALLEX data is linked to 3-week and 4-week runs.

4-week GALLEX data resembles GNO data.

Recent re-analysis results in a unimodal histogram.

Abstract

The histogram formed from published capture-rate measurements for the GALLEX solar neutrino experiment is bimodal, showing two distinct peaks. On the other hand, the histogram formed from published measurements derived from the similar GNO experiment is unimodal, showing only one peak. However, the two experiments differ in run durations: GALLEX runs are either three weeks or four weeks (approximately) in duration, whereas GNO runs are all about four weeks in duration. When we form 3-week and 4-week subsets of the GALLEX data, we find that the relevant histograms are unimodal. The upper peak arises mainly from the 3-week runs, and the lower peak from the 4-week runs. The 4-week subset of the GALLEX dataset is found to be similar to the GNO dataset. A recent re-analysis of GALLEX data leads to a unimodal histogram.