The CLOUD experiment involves an interdisciplinary team of scientists from 17 institutes in nine countries, comprising atmospheric physicists and chemists, and cosmic-ray and particle physicists. The Proton Synchrotron provides an artificial source of “cosmic rays” that simulates natural conditions between ground level and the stratosphere. A beam of particles is passed through the cloud chamber and its effects on aerosol production or on liquid or ice clouds inside the chamber are recorded and analysed.
The experiment includes an advanced cloud chamber equipped with a wide range of external instrumentation to monitor and analyse its contents. The temperature conditions anywhere in the atmosphere can be recreated within the chamber. All experimental conditions can be controlled and measured, including the “cosmic ray” intensity and the trace atmospheric vapours in the chamber, which are set to levels of only a few molecules per trillion.