9 Symmetry Violations and Quark Flavour Physics
585
ϒ(4S) in the laboratory, the KEKB electron beam has an energy of 8 GeV while the
positrons collide with an energy of 3.5 GeV. The highest instantaneous luminosity
achieved at KEKB was L = 2 × 10 34 s −1 cm −2 [71].
The Belle detector (Fig. 9.25) followed the typical onion-shape design. After an
exchange in 2003, a silicon vertex detector (SVD) made from four layers of doublesided silicon strip sensors was used as inner component. The innermost (outermost)
SVD layer was located at a radial distance of only 20 (88) mm from the collision
point. The impact parameter resolution for charged particle tracks obtained is [71]
σ r =
21.9 ⊕
35.5
p
μm [p in GeV/c] ,
σ z =
27.8 ⊕
31.9
p
μm .
The SVD was followed by the central drift chamber (CDC) which extended to
a radial distances of 88 cm. The combined tracking system of SVD and CDC
provided a good momentum resolution, especially for low momentum tracks, thanks
to the minimization of material. For the transverse momentum a resolution of
σ p T /p T = 0.0019 · p T ⊕ 0.0030/β [p T in GeV/c] was achieved [71]. Particle
identification was provided by the time-of-flight (TOF) system and by the aerogel
Fig. 9.25 Belle detector with the silicon vertex detector (SVD), the central drift chamber (CDC),
the time-of-flight-system (TOF) and the aerogel Cherenkov counter (ACC), the CsI electromagnetic calorimeter and the K L /μ detector (KLM). The detector is embedded in a magnetic field of
1.5 T produced by a solenoid with a length of 4.4 m and a diameter of 3.4 m [70]
585
ϒ(4S) in the laboratory, the KEKB electron beam has an energy of 8 GeV while the
positrons collide with an energy of 3.5 GeV. The highest instantaneous luminosity
achieved at KEKB was L = 2 × 10 34 s −1 cm −2 [71].
The Belle detector (Fig. 9.25) followed the typical onion-shape design. After an
exchange in 2003, a silicon vertex detector (SVD) made from four layers of doublesided silicon strip sensors was used as inner component. The innermost (outermost)
SVD layer was located at a radial distance of only 20 (88) mm from the collision
point. The impact parameter resolution for charged particle tracks obtained is [71]
σ r =
21.9 ⊕
35.5
p
μm [p in GeV/c] ,
σ z =
27.8 ⊕
31.9
p
μm .
The SVD was followed by the central drift chamber (CDC) which extended to
a radial distances of 88 cm. The combined tracking system of SVD and CDC
provided a good momentum resolution, especially for low momentum tracks, thanks
to the minimization of material. For the transverse momentum a resolution of
σ p T /p T = 0.0019 · p T ⊕ 0.0030/β [p T in GeV/c] was achieved [71]. Particle
identification was provided by the time-of-flight (TOF) system and by the aerogel
Fig. 9.25 Belle detector with the silicon vertex detector (SVD), the central drift chamber (CDC),
the time-of-flight-system (TOF) and the aerogel Cherenkov counter (ACC), the CsI electromagnetic calorimeter and the K L /μ detector (KLM). The detector is embedded in a magnetic field of
1.5 T produced by a solenoid with a length of 4.4 m and a diameter of 3.4 m [70]