CDC Construction Details

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The GlueX CDC

Overview

Construction

Details of the CDC Construction

Introduction

This page provides links to the documentation on the construction of the CDC at Carnegie Mellon University.

The aluminum endplate.


Global Documents

The initial CMU Contract Submission contains the contract, the Statement of Work (SOW) and the Technical Review Report. These documents were signed off on by both Jefferson Lab and CMU and the contract for construction started on May 15, 2010. As part of this work, CMU has provided an overall Quality Assurance Plan for the construction of the CDC.

  1. GlueX-doc:1438 Contract package - (Feb.2010).
  2. GlueX-doc:1619 Quality assurance plan - (Feb. 2010).
  3. GlueX-doc:1442 Summary of Tests - (Feb. 2010).
  4. Construction Schedule as a tiff file.
  5. Construction Schedule the FastTrack file.
Clean-room documents

The CDC will be built is a clean room that is measured to be better than class 10000. In order to maintain this level (or typically better) of cleanliness, a set of standard clean-room protocols have been developed by which all personnel using the clean room must abide. This include procedures for entry/exit, pass-thru usage, maintenance, and regular logging of particulate counts in the clean room and its vestibule.

Document Summary
  1. GlueX-doc:1630 CMU clean-room protocols - (Oct. 2010).
  2. GlueX-doc:1620 Clean-room log sheets - (Sept. 2010).
Assembly documents

The assembly of the CDC is broken into several phases as outlined in the EVMS system. Within each of these phases are various milestones and test data that needs to be performed. For each of these phases, a preliminary construction plan based on prototype work has been provided as part of the overall CDC Construction Plan. These have been updated with a preliminary plan for each activity which includes information on training, quality assurance and tests. Finally, as each phase is entered, a detailed plan is developed and written in the form of an instruction manual with photographs that details how each step is to be done. These detailed plans are developed in discussion with scientists, the construction manager and the technicians to both minimize the chance for error and optimize the process in terms of reproducibility and time involved.

  • Initial checks and chamber frame assembly and alignment.
  • Installation of straw tubes in the chamber frame.
  • Installation of the internal gas plumbing and the outer chamber shell.
  • Stringing of wires in the sraw tubes.
  • Installation of the upstream plenum.
  • Electrical connections to the chamber.
  • Installation of the downstream plenum.
  • Chamber performance tests.
Document Summary
  1. GlueX-doc:1280 CDC Construction Plan - (Feb. 2010).
Parts Acceptance Tests

All parts that go into the the CDC are checked to make sure that they are within design tolerances. If a part is out of tolerance, it is corrected if possible, and rejected if not possible. The parts that have been checked include the end plates, the straw tubes, the donuts which are glued into the straws, feed thrus which hold the straws in the chamber frame and the pin holders which hold the crimp pin in place.

Acceptance Results

The results of the acceptance checks are generally very good.

Part name No. Action Acc. % Notes
Al. End plate 1 some reaming 100%
Carbon End plate 1 extensive reaming 100%
Aluminum donuts 4000 extensive reaming ~100%
Plastic donuts 4000
Aluminum feed thrus 4000 extensive reaming ~100%
Plastic feed thrus 4000
Pin holders 8000
Straw tubes 4200 90% 2200 have been received
Document Summary
  1. GlueX-doc:1532 Straw tube acceptance checks - (June 2010).
  2. GlueX-doc:1533 Donut acceptance checks - (April 2010).
  3. GlueX-doc:1534 Feed thru acceptance checks - (April 2010).
  4. GlueX-doc:1626 Pin holder acceptance checks - (October 2010).
Frame assembly and alignment

The assembly and alignment of the end plates starts with the two end plates, the twelve connecting rods and the inner shell and hubs for the CDC. The frame is then put together on the assembly mandrill and then the two end plates are aligned and the inner shell glued in place. The preliminary procedure was based on the large prototype work at CMU. The final procedure was developed as during the assembly phase. This involved some tests to develop the best procedure to glue the inner shell into the frame and manufacture of several adjustable connecting rods to set the end-plate spacing near the inner shell.

Resulting Alignments Accuracy

The procedure used a self-leveling transit with a ~1 mil accuracy (as measured) to make sure that the 2-o-clock and 10-o-clock survey fiducials from both end plates all lie within a single plane. This was done to somewhat better than 2 mil accuracy.

Document Summary
  1. GlueX-doc:1451 Preliminary end plate alignment procedures - (Feb. 2010).
  2. GlueX-doc:1621 Final End plate assembly and alignment - (Oct. 2010).
Installation of Straws

The preliminary procedures were part of the overall construction plan. They have been updated in consultation with the entire construction team and developed into the final procedures.

The straw tubes need to be cut to length and cleaned. There are two lengths (straight and stereo) which are set with a hard stop on the cutting bench. The next step is to glue the donuts into the straws. Mixing the conducting epoxy is a crucial step due to the high cost of the glue. Once this is mixed, the donuts can be glued into the ends of the straws and resistance checks made. After the glue has cured, the straws can be installed in the chamber frame and glued into place.

Log sheets and travelers

During this phase of the construction, the batches of conducting epoxy will be logged and mapped onto the later numbers in which they were used. This information is recorded in an excel spread sheet known as the Glue Log.

Document Summary
  1. GlueX-doc:1440 Preliminary installation procedures - (Feb. 2010).
  2. GlueX-doc:1624 Cut and clean straws - (Jul. 2010).
  3. GlueX-doc:1622 Mixing the conducting epoxy - (Jul. 2010).
  4. GlueX-doc:1623 Glue the donuts into the straws - (Jul. 2010).
  5. GlueX-doc:1625 Straw insertion into frame - (Oct. 2010).
  6. GlueX-doc:1616 Glue log spread sheet - (Sept. 2010).


Install Outer Shell

The preliminary procedure for installing the internal gas plumbing and the outer CDC shell was developed as part of the construction plane. The final procedure will be documented as this task is performed.

Document Summary
  1. GlueX-doc:1629 Preliminary procedures - (Feb. 2010).
Wire Stringing and Tests

A preliminary procedure is based on the details from construction of the three prototype straw-tube chambers at CMU. The final procedure as well as training information will be developed at the start this phase of the project in consultation with all members of the construction team.

We note that if problems are encountered in this phase, wires can and will be restrung. Such problems can include lost tension or broken wires and would be identified by the tests. The measurement of wire tensions is an important part of this phase. A document describing the measurement of the wire tensions is available. A note is also available on the topic.

Log sheets and travelers

During this phase of the construction wire tensions will be checked and recorded. This information will be put in a excel spread sheet known as the Wire Stringing Log.

Document Summary
  1. GlueX-doc:1441 Prelininary wire stringing details - (Feb. 2010).
  2. GlueX-doc:1617 Wire Stringing Log - (Sept. 2010).
  3. Document describing the measurement of wire tensions.
  4. GlueX-doc:1632 Note on wire tensions.
Electrical Hook Up

A preliminary plenum installation and electrical hook-up plan was developed based on extensive prototype work at CMU. This plan is part of the overall construction plan. The detailed plans for the sub-phases of this part of the project will be developed in consultation with the entire construction team at the start if this phase.

Log sheets and travelers

During this phase of the project, careful records need to be maintained of what chamber (CDC) channel os connected to which preamplifier and preamplifier channel. This information is recorded in the Electrical Hook-up Log.

Document Summary
  1. GlueX-doc:1627 Preliminary electrical hook-up procedures - (Feb. 2010).
  2. GlueX-doc:1618 Electrical Hookup Log - (Sept. 2010).
Down-stream Plenum Installation

A preliminary procedure for the installation of the down-stream gas plenum has been developed.

Document Summary
  1. GlueX-doc:1633 Down-stream plenum (Oct. 2010).
Acceptance Testing of the CDC

A preliminary document describing the leak checks of the CDC, high-voltage tests, and cosmic tests while at CMU is presented here.

Document Summary
  1. GlueX-doc:1629 Performance checks of the CDC.
Related Information
  • Photos of the construction.
  • The CMU clean room.
  • Photos showing observed corrosion on the aluminum end plate of the CDC.