A Langsdorf cloud chamber as a complementary educational material to Cherenkov telescopes for the observation of cosmic rays

In 2015, the pGCT, a telescope prototype planned for the Cherenkov Telescope Array (CTA) gets its first Cherenkov light in the Meudon site of the Observatoire de Paris. As a part of the small-sized telescopes of the CTA, this telescope was designed to detect showers of secondary particles produced when very high energy gamma rays and cosmic rays enter in the upper atmosphere and interact with the atmospheric gas. It is now dedicated to a test bench for Cherenkov observation and to educational purposes. Within this last framework and in order to propose to the general public an easy way to observe high energy particles, we started in 2021 the development of a Langsdorf cloud chamber based on a previous model using Peltier cells and developed for students in Tours. Cloud chambers provide a convenient way to observe signatures of charged particles related to cosmic rays since they allow a direct detection also during daytime and are easier to use for the visits by the general public to concretely illustrate the existence of these high energy particles. This paper describes mechanical and electronic designs of this cloud chamber. Some results for educational purposes are also given.