Introduction

Resolution degradation of the CSC's have contributions from two major sources (i) due to tracks inclined from the normal to the face of the chamber, and (ii) due to the Lorentz angle of the gas mixture which is dependent on the gas mixture chosen for the tracking detectors. Therefore, the gas choice must be made with great care. In addition to the Lorentz angle there are other properties of the gas one should keep in mind. These include:

• The gas should possess fairly good electron drift velocity
• Diffusion of electron should be low
• The gas should have a stable operating plateau
• The gas mixture should be nonflammable and chemically not aggressive
• The CSC aging effect should be small