2 The CDF Experiment at Fermilab Contents - Harvard University ...

Section 2: Central Muon Extension 27
a larger project. These sections are called the \miniskirt" and although the extrusions are
the same as the arches, the construction is dierent.
Process
Single muon acceptance
CMU & CMP CMU & CMP & CMX Relative improvement
WH ! ``` 0.46 0.71 56%
tt prod. 0.48 0.71 50%
WZ prod. 0.36 0.58 61%
Inclusive W prod. 0.30 0.52 71%
Inclusive J= 0.18 0.33 81%
Table 4: Improvement in the acceptance for single muons when the CMX is included with
the CMU and CMP, for various processes
Detailed Design
Each 15 CMX wedge is made up of 48 chambers arranged in stacks of eight layers; the
chambers are staggered layer by layer and form four logical hermetic layers, yielding four
position measurements for each crossing muon. The wedges have a fan-shaped structure,
and the CMX system, once assembled, forms two conical sections centered on the beam axis
{a somewhat unusual shape for a set of drift chambers. Each conical section is composed of
four mechanically independent parts: two arches, the keystone, and a miniskirt which covers
the lower part of the azimuth (see Fig. 14). Each arch covers 120 in azimuth, the keystone
at the apex covers 30 , and the miniskirt covers 85 (there are 2:5 gaps at the boundary
between the arches and the miniskirt). The construction of the east and west sides of CDF is
the same, except that there is no keystone on the east side, due to a mechanical interference
with the cryogenics.
The anode signals from the drift chambers are amplied locally. Radeka preamplier hybrids
are mounted on boards which service four tubes each. There is also a provision for test
pulsing the four channels on any given preamp board. The signals are brought on shielded
cables to a rack mounted on the CMX arch. Custom designed amplier-shaper-discriminator
(ASD) boards produce dierential ECL signals which are carried to multihit TDC's housed
on the rst oor of the experimental hall. These TDC's have been completely redesigned