On the track extending in the opposite direction to the passage of an alpha-particle in diffusion cloud chamber

Diffusion cloud chamber shows some mysterious phenomena. Although α-particles pass their whole length of the passage within 10 ns, the extension of the tracks are visible. Also, an incredible phenomenon was found that the tracks extended in the opposite direction to the passage of α-particles. The reason of the latter one was confirmed experimentally and theoretically that the temperature difference existed along the passage of α-particle and the density of the excess supersaturated molecules of ethanol near the end of the passage of α-particle was a few times larger than that near the beginning of the passage. (author)