The drift chamber gas is composed of 50% Argon and 50% Ethane (by volume),
bubbled through isopropanol at 1
C. This results in gas containing
approximately 1% alcohol vapor. The mixing system that produces this
gas is housed in the gas shed. The bottles supplying the gas to the mixing
system are attached to two two-bottle manifolds outside the gas shed, within
the fenced-in gas bottle yard.