Drift Tube

  A stand-alone coaxial cylindrical drift chamber, made of a conducting-surface cylinder acting as cathode, and a sense wire stretched in the axis of the cylinder. The function is the same as that of a proportional tube , with measurement of drift time added. The simple construction achieves high gain and good proportionality.

Often, tubes are made of thin metallized foils (e.g. 25  kapton with an evaporated conductive layer), and arranged into densely packed layers or volumes; these can be used when short drift times are at a premium, like in high-rate environments. For a tube diameter of 4 mm, the maximum drift time (at the usual drift velocity) is 40 ns; they can thus be used for triggering. Such small-diameter tubes are also called straws, and a collection of them a straw chamber . High position precision and measurements are difficult; mostly, if the occupancy (hit probability) is not too high, single-hit electronics will suffice.