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

Section 2: CDF Hardware Projects 5
2.2 Hardware Upgrade Projects
The upgrades of the CDF apparatus are substantial. All of the tracking is being replaced,
and the Harvard group is involved in the two most important tracking subsystems: the
Central Outer Tracker (COT) and the Silicon Vertex detector (SVX). It also carries
full responsibility for the Central Muon Extension (CMX) which it built as an upgrade
to the muon system during Run I. Each of these projects is described below.
Much of the success of these undertakings is attributable to the excellent support sta
Harvard enjoys. John Oliver and Nathan Felt are responsible for the design of many important
electronics modules and systems, in particular, for parts of the data acquisition system
for the SVX. Jack O'Kane and Sarah Harder fashioned quickly and reliably many of the
boards and electronic devices needed by the Harvard CDF group. The skills and dedication
of Rick Haggerty and Steve Sansone in the machine shop guarantee the success of the COT
project of the CMX.
2.2.1 Central Outer Tracker (COT)
(Prof. Franklin, Dr. Burkett, Dr. Riegler, Mr. Hall, Ms. Madrak & Ms. Wessels)
Overview of Central Outer Tracker
CDF is upgrading detectors and electronics to handle luminosities higher than in previous
runs. The higher luminosity will be achieved by both increasing the number of proton
bunches, and by using a more ecient injector (the Main Injector) to the superconducting
synchrotron. At the beginning of Run II, the bunches will cross at CDF every 396 ns, and
in Run IIb, every 132 ns. The central tracking chamber in CDF Run 1 was known as the
CTC. The upgraded design, the Central Outer Tracker (COT), is similar to the CTC but
improves upon identied deciencies and accommodates the higher luminosity of Run II.
The maximum drift time has been reduced from 706 ns to 100 ns which means that events
will not overlap in the chamber. This is accomplished both by reducing the maximum drift
distance from 3.6cm to 0.88cm and by using a faster gas, Argon-Ethane-CF 4 (50:35:15).
The number of stereo layers has been increased from 24 to 48, which will improve tracking
resolution in the r , z plane. The CTC was segmented into nine super-layers, ve axial and
four stereo. The ve axial super-layers consisted of 12 sense wire layers, while the four
stereo super-layers consisted of only 6 sense wire layers. Thus there were only 24 stereo