4 Gaseous Detectors
121
Fig. 4.16 ATLAS MDT drift tubes: space resolution as function of impact radius and background
rates. Expected rates are ≤150 hits/cm 2 s [15]
Fig. 4.17 LHCb straw tubes: (a) Winding scheme. (b) Details of the double foil. Kapton XC is on
the inside [17]
A second type of tube design, straw tubes, has become very popular since a
number of years. Straw tubes offer high rate capability due to small diameters and
relatively little material in the particle path. In LHCb, where local rates (near one
end of the wire) up to 100 kHz/cm have to be handled, an internal diameter of
4.9 mm was chosen [17], with a construction shown in Fig. 4.17. Two strips of thin
foils are wound together with overlap. The inner foil, acting as cathode, is made
121
Fig. 4.16 ATLAS MDT drift tubes: space resolution as function of impact radius and background
rates. Expected rates are ≤150 hits/cm 2 s [15]
Fig. 4.17 LHCb straw tubes: (a) Winding scheme. (b) Details of the double foil. Kapton XC is on
the inside [17]
A second type of tube design, straw tubes, has become very popular since a
number of years. Straw tubes offer high rate capability due to small diameters and
relatively little material in the particle path. In LHCb, where local rates (near one
end of the wire) up to 100 kHz/cm have to be handled, an internal diameter of
4.9 mm was chosen [17], with a construction shown in Fig. 4.17. Two strips of thin
foils are wound together with overlap. The inner foil, acting as cathode, is made