Minutes-3-13-2008
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FDC Weekly Meeting
Date: March 13, 2008
Participants: Daniel, Simon, Brian, Kim, Chuck, Roger, Mark
Next Meeting: March 20, 2008 @ 1:30 p.m.
Contents
Test Frame Wire Winding
- The Phase 1 wire winding contract is now officially signed and in place. - Over the next week, IUCF will be preparing a GANTT timeline chart to organize the work. They will also begin setting up the wire measurement system. They have asked us to send them drawings with enough detail that they can prepare a support frame for the wire planes during the wire winding process. We all felt that the existing strongback would fulfill this purpose. DSC will contact Keith Solberg at IUCF to pass along this information. Simon will take some photographs of a test wire plane mounted to the strongback to see if this will work. A separate frame (possibly) will need to be designed to support the wire frame vertically for the wire scanning measurements. - IUCF has also asked us to send them samples of the epoxy to be used for the glue strip. Brian has ordered this and it should arrive early next week. We will then arrange to send them the epoxy shortly thereafter. - Brian put the wire frame transport box into a JLab van and taken it out for a test ride around the roughest parts of town to ensure the system is stable and well cushioned. Based on these tests, he has added more foam/support inside the box to be sure the wire frames cannot bounce around. - Brian prepared a slide with two samples of our sense wire (20 micron diameter gold-plated tungsten) and two samples of our field wire (80 micron diameter gold-plated copper-beryllium) for study in the W&M electron microscope. Jose Riso (from Hall B) scanned the wire and reported back to us the results. The tungsten wire appeared to be of very good surface quality. The copper-beryllium suffered from a number of pitting and trench defects. This spool will not be of sufficient quality to use in the production winding, but was viewed as good enough for the test and prototype winds. See GlueX-doc-1002 for a detailed write-up. - Brian has been in contact with Tom Elliott who is a JLab expert on electroplating. Tom will perform some electroplating tests on our tungsten sense wires using an old anode-wires-only plane for the small-scale prototype. He will employ a copper-sulfate solution and set up the parameters for this test. We can then work to optimize the setup for the full-scale wire planes. This test work should be completed in about a week.
Full-Scale Prototype
- Procurement for the prototype is now proceeding in earnest. Note that all PRs that are provided to Elke should include clear information on what the PR is for. - The wire frame circuit boards should arrive at JLab next week. After a QA inspection, they will be provided to Greg Arnold's group at JLab for Phase 1 stuffing. This will only amount to the resistors on the boards as the HV capacitors (on order) have a long lead time. - The PR for the G10 has been signed and the G10 is expected to arrive in about 3 weeks. - The Rohacell order is expected to be delivered in about 2 weeks. - The PR for the rails and support hardware has been signed. As Bill was not at the meeting, we do not yet know when to expect delivery. It may be that the supports that attach the chambers to the rails will actually be manufactured in the FSU machine shop. - The PR for the cathode daughter boards and cathode ground boards should be sent out for signatures in about a week (or less). Chuck is working to tell us where the 10th cathode daughter board (the aforementioned ground board) can be placed on the cathode ring. We should order 6 of each board for the prototype. - We ran into a bit of a snag with our cathode board manufacturer (the board house -- CCT Marketing, not the supplier). They are effectively going into bankruptcy and indicated (initially) that they would not be able to prepare our boards. Since the initial email from them, Roger has been in communication with their technical representative (Dave Lasky) who indicated that we may still be able to get our cathode manufactured at CCT before they shut down. We will know early next week. We will have the Gerber files for these boards ready early next week. Part of question is whether we can get material from our cathode board supplier (Sheldahl) on the right time frame. We plan on procuring 8 complete cathode board sets for the full-scale prototype. - We have not heard back from Dennis Skopik on our clean room request. It might be that we can take occupancy of the EEL clean room tent within a few weeks. Brian will finalize occupancy details with Jack Segal (manager of the space). - Brian will begin to put together an order for a second construction table (granite surface plate and aluminum construction jig). - Some known delivery time lines: Wire frame boards by March 27, 50-pin connectors for wire frames this week, 50-pin connectors for preamp daughter boards by July, ERNI connectors by the end of May, HV capacitors by May 9.
Composite Cathode Updates
- No further progress has been made on completing the construction of
the full cathode prototype sandwich (cathode-ground plane -cathode).
Brian will get back to this within the next week. He wants Denny
to be present for this work to teach him all the steps involved.
Presently Denny is unavailable due to commitments in Hall B and
we are planning for Denny to be available during the full-scale
prototype construction in the April to June time period when Hall B
is running for physics.
- So far Brian has completed the mounting of one cathode plane (3 boards)
on the composite frame. He still has to include the ground plane
and the second cathode (to make a complete sandwich). In this work
he will seal the back of the 2-mm support Rohacell with a 12 micron
sheet of Kapton. He will test of ground plane connection scheme using
the faston connectors. He will also install gas inlet and outlet
ports through the Rohacell (he will circulate a design drawing for
the gas ports shortly).
- We have come to a temporary conclusion about the vibration analysis
and studies. Tim does not think that the design issues with
vibrations are a major priority now. A back of the envelope calculation
by Tim estimated a natural cathode vibration frequency in the few
Hz range and the important Hall D sources will be at 60 Hz and 120 Hz.
He recommends a simple study with the prototype before calculations
are done.
- Brian has completed a stretching test of our full-scale Kapton boards.
This was a worry due to the very tight tolerances on the cathodes.
Stretching or distortion of these boards during the construction
procedure could be quite problematic. We do not expect that Kapton
will be able to stretch too much, but this needed to be quantified.
Brian's report on the results is:
* I measured the stretch from "wetting the film flat" of a section of CCT
produced Kapton cathode material. The sample was from the center PCB
(FDC1) made with 25 micron thick Kapton with 5 micron thick copper
strips. An optical periscope was used to locate the position of the
ends or sides of the copper strips. The first measurement was made with
the PCB in a relaxed state lying loose on a piece of aluminum tooling
plate. The second measurement was made after PCB was wet to the tooling
plate and rolled flat using a fingerprint roller. The PCB was rolled
until all wrinkles were pulled flat and then remeasured. The PCB was
first measured between two points at the ends of a strip, parallel to
the strip(x axis). A second measurement was taken between the edges of
two strips, perpendicular to the strips(y axis). The plate was attached
to a Milltronics RH30 CNC bed mill. The coordinates were taken from the
mill's display.
X axis Measurement, parallel to the strips;
#1 x axis before rolling 38.0301"
#2 x axis after rolling 38.0327"
Stretch 0.0026" - .007%
Y axis measurement, perpendicular to the strips;
#1 y axis before rolling 5.1970"
#2 y axis after rolling 5.1989"
Stretch 0.0019" - .037%
The bottom line is that stretching of the Kapton films is not an
issue to worry about.
- As reported in last week's minutes, Roger wanted to get a piece of
scrap cathode board to do some soldering tests with the rigid flex cable.
This was not discussed this week but we will get a report at the
next meeting.
Grounding Issues
- Fernando will supply an overall grounding specification document by next week (probably). - Fernando was given a piece of our ground plane material of size 1m x 2m to measure the surface resistivity of this material. - Kim has distributed samples of the male and female versions of the faston connectors that we are nominally planning on using to make the ground connections to the wire frame boards, the cathode boards, and the ground planes.
Gas Volume Definition
- Bill has provided Dave Meekins with our parasolid model to study the gas flow. Dave has gotten started on the calculations. The first model that he has includes the central beam hole in the cathodes, as well as a series of holes on both sides of the cathodes between the last cathode strip and the G10 frame. The goal of these studies is to finalize the layout of the cathode penetrations to allow for good flow through the chamber. Dave has promised to have first results to us in a few days.
Cathode Board Discussion
- Before we can submit the cathodes for manufacture, we need to finalize our discussions with both the board material supplier and the board house regarding our flatness and handling specifications. DSC has completed a document that Roger will pass on to the technical representatives at the material supplier and board house. - Roger will prepare the QA/stuffing/cleaning documents for the cathodes and cathode daughter boards referencing the global document that Fernando has already posted (GlueX-doc-991). - We are still actively pursuing leads for a board house backup. Roger has been in contact with a board house in Missouri (Via Systems). More details will be provided if they can make our boards. Also, Fernando has been pursuing leads with 3M in Germany. As Fernando was not at the meeting, we do not know the status here. He was going to get Elke to help out in talking to folks (in their native tongue). - Note that the full-scale prototype chamber cathode boards will be spec'd to have a gold-flash on the connector area to improve surface for soldering. - Roger reported (based on a discussion with the CCT cathode board house technical representative) that they followed IPC specifications for board flatness in manufacturing our 5 micron dummy cathodes. This is not a good sign as these boards suffered from noticeable surface quality issues. We will have to work with the supplier and board house to ensure proper handling.
STB/HVTB Discussion
- Kim will prepare a document on board QA/stuffing/cleaning for Greg Arnold. She will act the contact point for Greg. - Kim has passed onto Brian the details for the needed modifications to the aluminum tooling plate jig for wire frame construction. This work is needed for the jig plate to clear the pre-stuffed components on the circuit boards. The work will be completed within the next several weeks.
Small-Scale Prototype
- As announced in last week's minutes, problems came up with the soldering of the connectors to the cathode boards using conventional soldering techniques. Coming up with a low-temperature solder seems to taking too long. DSC has stated that we want these boards in our hands sooner rather than later. Brian will talk to Bill Gunning about our connector mounting options to get the job done ASAP. This will most likely be done with a solder paste and hot-air gun. If this fails we will investigate a conducting epoxy approach. - If the mounting can be completed in the next several days, Simon will install them and perform some initial tests.
Cathode Flatness Measurements
- Bill has made contact with Hexagon Metrology in North Carolina. They can try to measure the surface flatness of our cathode prototypes. They are not sure if their laser triangulation system will work with our cathode surfaces. However, we believe that this is a reasonable option to pursue. The costs are $1k/day. We will also pursue procuring our own system. DSC will talk to Bill about this in the next several days. One question that came up, can we supply a sample of our cathode boards to the outfit that sells the system to get some idea if it is compatible with our boards?
Upcoming Reviews
- The combined tracking/PID review for Hall D is scheduled to take
place on March 27 and 28. We are presently working on the TDR
and the talks. Complete details are given on the Hall D web site
(http://www.jlab.org/Hall-D/guest_secure).
- In preparation for the meeting, we will need an updated set of
design drawings for the FDC web site. New drawings from the
mechanical model will need to be provided that reflect the current
design.
Drawings
- DSC has collected all of the available FDC subsystem design drawings and placed them on the FDC website. The URL is: http://www.jlab.org/Hall-D/detector/fdc/drawings.html. Folks should go through the drawings and let DSC know what drawings and/or categories are missing for a complete design set. - Also folks should send DSC the latest design drawings where there have been changes to keep this web site up-to-date through the review season.
Work List
- The FDC short-term work list has been posted on the FDC web site (see http://www.jlab.org/Hall-D/detector/fdc/). This is continually being updated and DSC welcomes any feedback or comments from the group.
Minutes prepared by Daniel. Send any comments or corrections along.
