Technical informations

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The central inner z-chamber CIZ (as well as the central outer Z-chamber COZ ) is designed to measure the z-coordinate of the track position much more precise than it is achieved by charge division of the CJC signals.
The sense wires are strung concentrically and perpendicular around the beam axis. The cross section of CIZ forms a 16-edge- and that from the COZ a 24-edge-polygon. The CIZ (COZ) is subdivided into 15 (24) rings in z with each ring having four wires. The active regions covered by CIZ (COZ) are given together with those of the CST and CJC in Table 1

  Radial z Polar
  min [cm] max [cm] min [cm] max [cm] min [°] max [°]
CST 5.75 9.5 -17.5 17.5 30 150
CIZ 17.4 20.0 -108.0 72.0 13.6 170.8
CJC1 20.3 45.1 -112.5 107.5 10.7 169.7
COZ 46.0 48.5 -110.5 105.5 23.6 157.3
CJC2 53.0 84.4 -112.5 107.5 26.3 154.7
Table 1

The CIZ sense and potential wire planes in the drift cells are tilted with respect to the beam axis by 45°. This leads to a tilt of the drift field isochrones of about 30° which is in contrast to the COZ where the sense wire plane is normal to the beam axis. The field lines are distorted such that a track penetrating the cell leaves signals on only three of the four sense wires. Tracks crossing on the right side produce signals on the wires 0,1 and 2, and those crossing on the left side give signals on the wires 1,2 and 3. The orientation of the wire plane as shown in Figure 1

Figure 1
corresponds to the ring numbers 9-14 of the positive z-region. The tilt changes to the opposite direction for the negative z-region (rings 0-8). Cell coordinates (z',u) are defined with the z'-axis parallel to the beam axis and the u-axis normal to the wire and the beam axis and the origin at the center of the drift cell. Geometrical parameters of the CIZ and the COZ relevant for the calibration are summarized in Table 2

  Units CIZ COZ
Number of Rings   15 24
Drift cells per ring   16 24
Drift cell length (cm) 12.0 9.0
Drift cell heigth (cm) 2.0 2.4
Sense wire per ring   4 4
Tilt of sense wire plane (°) 45 0
Radius at cell center (cm) 18.81 47.25
Sense wire
position (z',u)
with respect
to cell center 		wire 0 (mm)
wire 1 (mm)
wire 2 (mm)
wire 3 (mm) 		z'=7.0         u=-7.0
z'=2.0         u=-2.0
z'=-2.0       u=-2.0
z'=-7.0       u=7.0 		z'=0.0       u=-9.0
z'=0.0       u=-3.0
z'=0.0       u=3.0
z'=0.0       u=9.0
Table 2

More informations concerning construction, performance, calibration etc. may be found elsewhere:
Thesis of P. Robmann (office Zürich), M. zur Nedden , S. Hengstmann or
Journal: P. Robmann et al., Nucl. Instr. and Meth 277, 368 (1989), S. Egli et al., Nucl. Instr. and Meth 283, 487 (1989).

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