Physics: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 [math]\displaystyle{ \mu }[/math]m 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 dE/dx measurements are difficult; mostly, if the occupancy (hit probability) is not too high, single-hit electronics will suffice.