1 - THE DIFFUSION CLOUD CHAMBER

Abstract

Publisher Summary This chapter discusses the diffusion cloud chamber. Expansion cloud chambers have been extensively used in cosmic ray research, and early experiments used randomly operated chambers. The rate of amassing data was limited by the short duration of the sensitive time after expansion and also by the long recovery time between expansions. It was the work of Langsdorf, who used a thermal gradient to obtain conditions of supersaturation, that gave the most promising results. To use one-dimensional equations to describe the diffusion and heat transfer, the effect of the walls of the chamber must be neglected, and for further simplification of the theory, the vapor is treated as a perfect gas. For stable conditions in the diffusion chamber, the density of the gas vapor mixture must decrease with the height above the base. Diffusion chambers have been largely operated using solid carbon dioxide as the primary coolant and cold temperatures have consequently been limited to about −70°C. It is desirable to achieve as great a sensitive depth as possible to utilize the chamber efficiently. Diffusion chambers have rather limited application in the field of cosmic ray research. However, it is possible that they may prove useful in the study of the structure of extensive showers where the simplicity of operation would allow several chambers to be employed in an experiment. They may also be used with counter control.