The following post list the winners of WSC 2021.
The winning submission of the non-photographic media category shows us the Wilson cloud chamber. It was made by Maxim Bilovitskiy.
Comment from the author:
My name is Maxim Bilovitsky and I am a science popularizer and video blogger from Estonia. For some of my videos on radioactive elements, I wanted to visualize radiation, so I decided to use the well-known cloud chamber. For this experience, I took an ordinary kitchen pan and bought some dry ice along with a small glass fish bowl. After that, I fixed a few sponges soaked in ethanol to the bottom of the aquarium. I put the aquarium itself on a baking sheet cooled with dry ice, after which I waited about 15 minutes until the cold surface was covered with a layer of supersaturated ethanol vapor. As soon as the cloud chamber stabilized, it became possible to observe thin tracks from cosmic rays and background radiation in the ethanol vapor layer, but they were not very contrasting. For the best effect, I put several alpha sources in the chamber, for example, thoriated tungsten electrodes for TIG welding, as well as an americium source from a smoke detector. As soon as alpha particles began to fly out of the decaying radioactive metals, they began to ionize air particles in their path, while causing the supersaturated vapor from ethanol to condense behind them, creating the so-called alpha tracks. Tracks from alpha particles are very contrasting, but at the same time not very long, no more than 5 cm, since after hitting the gas molecules from the air, a heavy alpha particle loses all its energy and turns into helium. In addition to alpha tracks, in the cloud chamber one can also observe tracks from beta sources, which are much longer, but all the same, they are less contrasting, and therefore they can be poorly seen in a makeshift cloud chamber. For better visualization of the tracks of all possible particles, as well as cosmic rays, it is better to use industrial cloud chambers with a connected high-voltage source to remove excess ethanol drops at the bottom of the chamber.
Comment from the jury:
The invention of Wilson’s cloud chamber was a crucial innovation in the field of atmospheric science and later in the field of experimental particle physics, due to its use as particle detector for visualizing the passage of ionizing radiation.
Its inventor Charles Thomson Rees Wilson was awarded the Nobel Prize in Physics, but he is probably less known compared to other laureates. This file brings attention to it, and the more curious reader can start to navigate this topic and discover more about the history of physics. The video is short and also effective in the choice of accompanying music, making the explanation even more structured. The apparatus is also presented with a dedicated focus on its main components, raising curiosity about the science behind it.
Files were published under CC BY 4.0 license.