Muon Chambers

Introduction

Along with my colleagues at the University of Illinois, I upgraded the Central Muon (CMU) chambers of the CDF detector, to prepare them for Run II. In Fall 2003, along with colleagues from Northweastern University, I commissioned the low-phi part of the Central Muon Extension (CMX) detector (the "miniskirt") that increased the muon acceptance by 15%. Since 2003, I am a CDF muon expert, especially responsible for the CMX detector.

CMU chambers upgrade

Because of the increased luminosity of the Run II Tevatron, the CMU chambers had to be operated in proportional mode. For this reason, a new amplifying system was needed: new preamplifiers, amplifiers, shaping circuits and discriminators. This new electronics was all built and tested in Urbana. I was involved with assembling the front-end electronics, removing the CMU chambers from the detector, replacing the front-end electronics and testing them with cosmic rays and pulser signals from the amplifier-shaper-discriminator. The testing set-up can be seen in my drawing below (click image for a larger version):



I was also responsible for determining the calibration constants for the chambers by injecting charge to three different places along their length and analyzing the chambers' response. Some photographs from the upgrade can be seen below (click on them to see the bigger version)

Preparing to remove the chambers from the central detector:
Removing them and storing them

Storing them and testing them (notice the cosmic telescope):
The new front-end electronics:


The ASDs and TDCs complete the picture and the same is true for all muon systems of CDF (click image for a larger verion):

Commissioning of the CMX "miniskirt"

In late summer and fall of 2003 I commissioned the low-phi part of the CMX detector (the "miniskirt") that increased the muon acceptance by 15%. (I also worked for the commissioning of the "keystone" before that). The colored ranges in the following plot show the Run II additional muon coverage (red and blue are parts of the CMX system, orange is the extension of the CMP system)


Commissioning the CMX miniskirt was a big project that included:
  • Installing the new front-end electronics and testing them with pulser charge
  • Installing the miniskirt chambers (partly under the CDF floor)
  • Solving gas leakage problems by by-passing the problematic chambers
  • Testing the chambers (as well as the ASD-TDC system) using cosmic rays
  • Solving preamplifier and low-voltage problems
  • Solving high-voltage problems (often by-passing)
Most of the miniskirt is under the floor and all of it under the steel:

Left: the miniskirt chambers with the scintillator on top of them. Right: the covered front-end electronics:

Maintaining the CMX

Since 2003, I am the muon expert of CDF, responsible for the optimal operation of the detector system and facilitating the CDF shift crew to record high quality data with the best possible acceptance.



Most common problems include:
  • Chambers not holding high voltage, due to humidity or/and physical damage
  • Oscillating or dead preamplifiers
  • ASD/TDC problems or signal-cable problems
  • Low-voltage or High-voltage supply issues
  • Scintillator Triggering issues
The following schematic shows all possible sources of a problematic signal: