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The new CDC page is Central Drift Chamber

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Row one in CDC.
The aluminum endplate.

The GlueX Central Drift Chamber

The CDC is a straw tube chamber that sits around the target in the GlueX experiment. The straws nominally run parallel to the beamline with readout on the upstream end of the chamber. About half of the straws are tilted with a 6 degree stereo angle to provide a measurement of the z position in two regions along the track. Tracks going more forward than about 30 degrees will also be tracked by the forward drift chamber system in the GlueX detector (FDC).

The 1.6 cm diameter straws are arranged in 28 radial layers. The inner-most layer is at about 10 cm and the outermost is at about 57 cm from the beamline. The chamber is anticipated to achieve a 150 micron position resolution in the r-phi plane, which when conbined with the stereo information will yield a number of z measurements with resolution of about a mm.

The most up-to-date description of the CDC is found in GlueX-document 990 which can be found on the portal . There are also up-to-date geometry tables in GlueX-document 979. There were also changes to this design that have been documents in GlueX-doc 744 and in document number 764 is the budget justification information for the chamber. All older documents should be considered out of date and probably inaccurate.

General information on charged particle tracking in Hall-D can be found on the Charged Particle Tracking wiki page.

The CDC is being built by the Medium Energy Physics group at Carnegie Mellon University . The current members of the CMU group involved in this effort are:

  • ) Curtis A. Meyer
  • ) Gregg Franklin
  • ) Yves Van Haarlem
  • ) Naomi Jarvis
  • ) Gary Wilkin

Draft v1.0 of CDC NIM paper.

CDC Construction

Fabrication Documentation

Production Documents


More on construction

Mechanical tests

With the cooperation of Tim and Slava we plan to do a couple of mechanical tests. During the review it was mentioned that we need to do more of these tests.

Leak tests

Wiring test

Sag test

Measure the thickness of the Al inside the straw

Sag, compression, and twist test

Electrical hookup pics

CDC Electrical Hook Up Photos

Prototype studies


dE/dx 350 MeV pions/protons

dE/dx 350 MeV pions/kaons/protons

dE/dx 250 MeV pions/kaons

H20 contamination tests

Old prototype

Photographs of the older, larger, CDC Prototype

New prototype

Energy/Amplitude as a function of drift time

Gas leak tests

Setup and tests

First signals

Gas mixture tests

Pictures of the prototype


Planned mechanical/construction tests


More resolution studies

Heated gas measurements


22 February 2008


ASIC meeting June 14, 2010

Charge division

Measuring Fe-55 X-rays with %2 interposer board

Electronic chain simulation

ASIC design optimizations

ASIC design optimizations tests writeup

Shaper gain

fADC timing

125 MHz Clock test

CDC High Voltage Board (HVB)


Preamp 2

Preamp 3

Preamp4 (GlueXdoc1364 Tbl 2 Row 2)

This section (blue background) contains links to data obtained when our gas mixer was not operating reliably.

On June 23, we came to the conclusion that our old preamplifier bit the dust. Detailed pictures showing how its performance has changed over the last several months are below. These clearly show that the gain increased by a factor of at least four and that there is substantially more noise. This later turned out to be confusion caused by a faulty mix of gas.

The following link points to comparisons of cosmic data taken with the old preamplifier several months ago and with the new preamplifier. They clearly show that the signals (for the same gas and voltage settings) are larger with the new preamplifier.

The following plots are taken using the new preamplifier with our FADC range decreased to match the lower maximum output voltage from the new preamplifier (about 500mV). The old preamplifier had a higher limit (~1V).

Based on the fact that our old preamplifier died, the following plots should not be used to make comparisons between the old and new preamplifier.

(end of dodgy gas section)

Noise studies



CDC Documentation

CDC Bi-weekly Status Reports (2007-8)











March 2008: PID/tracking review

GlueX CDC design and construction

GlueX CDC design and construction talk