Design and Construction of the Central Tracking Chamber

The Belle central drift chamber, CDC, was designed and constructed to meet the requirements for the central tracking system [30,31]. Since the majority of the decay particles of a $B$ meson have momenta lower than 1 GeV/c, the minimization of multiple scattering is important for improving the momentum resolution. Therefore, the use of a low-Z gas is desirable, while a good $dE/dx$ resolution must be retained.