A Hydrostatically Supported Cloud Chamber of New Design for Operation at High Pressures

Abstract

A medium‐sized cloud chamber for high pressures is described in which the pressure is sustained by the walls of an oil‐filled steel container rather than by the glass parts of the chamber itself. The chamber is 30 cm in diameter and 9 cm deep, and it was designed to operate at pressures up to 200 atmospheres. When filled at this pressure with argon the gas in the chamber has a stopping power for cosmic rays traversing the diameter equivalent to 80 meters of the atmosphere, 10 cm of water or nearly 1 cm of lead. Because of its high stopping power and a long period of sensitivity this chamber, at the maximum pressure, is approximately one thousand times more effective per expansion for studying rare cosmic‐ray phenomena than the largest chambers which have been operated at normal pressure. Details of the cloud chamber and its auxiliary devices are described.