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

Section 2: Central Muon Extension 29
Figure 14: The \miniskirt" drift chambers and scintillation counters comprising the lower
90 of the Central Muon Extension (CMX). There is one such set for each side of the CDF
detector.
for Run II, since the requirements on data acquisition rates are much more stringent than
in Run I.
The CSX scintillators are mounted on the interior and exterior surfaces of the wedges.
They are staggered with respect to the azimuth and each covers 3:75 ; in order to provide a
perfect t to the unusual design of the CMX system, these counters are built with a slightly
trapezoidal shape. There is one phototube on each scintillator; however, the orientation
on the interior and the exterior is opposite. This allows precise timing information to be
calculated from the sum of recorded times. (For the miniskirt there can be only one layer
of scintillator, due to space limitations. These scintillators will be instrumented with two
phototubes.)
Problems & Challenges
Our rst problem was the commissioning of the four CMX arches which contain the bulk
of the CMX chambers (Fig. 13). These were erected before Run Ib by individuals who are no
longer involved in the CMX. Our rst challenge was to understand how the system works,
and to repair whatever was not in good working order. Schmitt met this challenge after
arriving in 1998, assisted by undergraduate Kris Chaisanguanthum and graduate student
Hak-Ho Lee. Chaisanguanthum will be returning to Fermilab this summer, together with
undergraduate Caolionn O'Connell, to help assemble the miniskirt, as discussed below.