Fig. 2: Charge identification for tracks #4 and #5.

The distribution of α track volumes relative to that of track #4 (a) and track #5 (b), respectively, at different distances from the stopping point to the initial point of tracks in the emulsion sheet. From these volume distributions, a statistical hypothesis test was conducted to determine whether tracks #4 and #5 were similar to the alpha tracks (null hypothesis, H0) or not (alternative hypothesis, H1). c clearly displays an increasing confidence level for rejecting H0 as the range of track #4 increases, ultimately reaching a cumulative confidence level of 2.4σ at the maximum range of track #4. In contrast, d exhibits no significant confidence in rejecting H0 across the entire range of track #5.