Difference between revisions of "Minutes-3-25-2010"

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#* wire sample measurements [http://www.jlab.org/Hall-D/detector/fdc/new_reports/  wire sample reports ]
 
#* wire sample measurements [http://www.jlab.org/Hall-D/detector/fdc/new_reports/  wire sample reports ]
 
#* updated FDC naming convention [http://www.jlab.org/Hall-D/detector/fdc/tracking/FDC_NamingConvention.pdf naming convention]
 
#* updated FDC naming convention [http://www.jlab.org/Hall-D/detector/fdc/tracking/FDC_NamingConvention.pdf naming convention]
 +
 +
= Minutes =
 +
 +
Participants: Lubomir, Eugene, Bill, Daniel, Glenn, Casey, Mark, Beni, Simon, Fernando
 +
 +
= Production space update =
 +
 +
Two options are being considered. Properties behind Office Depot (preferably "Minuteman Press") and properties around Middle Ground Blvd (at Blue Crab) . The rent price of the latter is half the one at Office Depot, but requires building
 +
a room inside the bay area.  Our position is that he most promising for FDC construction that needs only minimal modifications is the "Minuteman press". We can share the bay area with SRF (John Hogan). 
 +
 +
== Electronics ==
 +
 +
- Fernando presented measurements comparing the discriminator part of the pre-amp cards. The worst card so far is showing ~30% variations (min - max range). The question was whether this is acceptable. We all agreed that we don't want to modify the design of the cards.
 +
 +
<!--
 +
 +
- Next week the design of the PCBs will be finalized (Fernando, Kim, Dan) and posted on the web. We discussed also the option of having checking points on the resistors at the   
 +
 +
- Tim organized a visit to off-site properties (across the street) that could be used
 +
for FDC production/storage purposes. We are considering this as a possible option that needs to be further investigated. There was a second meeting after this one, discussing the requirements to use the space for the FDC production.
 +
 +
- Fernando is working on the procurement of the HV and signal cables/connectors. He wants to make sure the lengths of the cables corresponds to the up-to-date plans.
 +
 +
- procurement of the cathodes: Roger and Dan are finalizing the cathode modifications. Eugene suggested to investigate the failure rate in soldering the flexes. Another showstopper is the decision about the size of the hole of the cathode strips. This issue was discussed during the last tracking meeting and Alex will investigate the effect of the copper material on the detector rates. We aim to have the same hole size on all the FDC packages. Fortunately, the decision about the the size of the wire deadening area that defines the sensitive area of the chamber, can be done later.
 +
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== Full scale prototype tests ==
 +
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- Beni finished the tests with Sr source, the prototype was moved back in the tent and the top layer was opened.
 +
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- Beni summarized the results of the plateau and drift time investigations with different gas mixtures. So far there's nothing unexpected. Nevertheless, there are concerns about the uniformity of the detector response and the quality of the gas inside the chambers. Systematic analysis of the full scale prototype tests will be prepared for the next meeting. Lubomir showed results from the tests with 55Fe: the energy resolution is about 7%. 
 +
 +
- At the end of the testing, Beni made a series of HV studies with CO2 only. Before and after opening the chamber he repeated the same tests. At all of the sectors, except maybe few, he was able to reach much higher HV than with Ar - CO2 mixtures.
 +
 +
- We observed corona discharge (bluish light barely visible in the darkened tent) at several places in one HV sector (at about +2700V/-400V) of the opened top chamber. The light was visible on the soldering pad of the last (for the sector) sense wire, later along the whole wire, and then on all the wires in that sector. Also we saw different spots blinking for few seconds coming from some dust on the wires. The corona discharge requires conductivity between places with different potential (through the air, or on the board) but is visible at places like edges or thin wires with very high electric field. 
 +
 +
- All this suggests that so far there are no indications that the HV problems are related to the boards, except maybe at few places due to impurities. The dust on the wires could explain at least some of the HV problems we had during the test. Dan suggested to clean the wires with alcohol and ionized nitrogen and continue the HV tests.
 +
   
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- Bill informed us about the frame modification work: the one-piece g10 wire frame came from the shop and Casey and Mark are working on the frames. The work will continue next week.
 +
 +
== Wire frame update ==
 +
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- Fernado is reviewing the modified PCBs, waiting also the diagnosis of the HV problems
 +
 +
- new wire sample measurements were posted
 +
 +
== Wire winding ==
 +
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- Keith Solberg is reviewing the plans for wire winding upgrades prepared by Bill
 +
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- Lubomir suggested to measure the capacitance of one wire, which parameter enters in the calculations of the tension specs. Fernando can provide a capacitance meter.
 +
 +
- Brian suggested to investigate the aging of the wire deadening. In this line, Eugene mentioned that the weight of the copper in that area should also be taken into account when calculating the tension specs.
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== Other ==
 +
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- Lubomir prepared a short description of the FDC naming convention. There were several suggestions to improve the convention. A modified version will be ready for the next meeting.
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 +
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[http://www.jlab.org/Hall-D/detector/fdc/frame_redesign.pptx frame design changes].
 +
  - The redesigned frame piece for the wire board is expected back from
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    the shop shortly.
 +
 +
==Wire Frame Update==
 +
  - The wire frame construction document is located at:
 +
    /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 +
  - The review of the FDC PCBs is now underway. Preliminary comments from
 +
    DSC and Bill passed on to Fernando. He will complete his preliminary
 +
    review in the next several days. We will send the boards to Keith for
 +
    comments after initial questions are fully addressed. The plan is not to
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    move forward with procurement until after inspection/diagnosis/repairs
 +
    of the HV/current problems seen in the full-scale prototype.
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  - DSC is finalizing the tension specifications for winding. It looks like
 +
    the +/-5% spec is unnecessarily tight. Looks like +/-20% is full
 +
    satisfactory, although we will likely put a +/-10% spec on the Phase 3
 +
    winding requirement.
 +
 +
==Cathode Update==
 +
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  - We would like to push to get the cathode board procurement started by the
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    mid-April
 +
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==Prototype Testing==
 +
  - The current version of the full-scale prototype test plan is on the
 +
    GlueX portal as ([http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1304 GlueX-doc-1304]).
 +
 +
  - Two layer test update: See the [http://www.jlab.org/Hall-D/detector/fdclog/ FDC Log Book] for updates on the continuing work.
 +
  - The delivery of the remainder of the preamp cards for the full-scale
 +
    prototype will be in mid-March.
 +
 +
 +
   
 +
==Construction Updates==
 +
  - The sense wire SEM checks are now complete and the wire sample reports
 +
    have been posted on the FDC [http://www.jlab.org/Hall-D/detector/fdc/new_reports/ Wire sample reports].
 +
 +
  - The original document for the [http://www.jlab.org/Hall-D/detector/fdc/design/phase3_work.pdf Phase 3 Preparation Work] will be reviewed
 +
 +
  - Master list on wire and cathode frame redesign work is located at:
 +
    [http://www.jlab.org/Hall-D/detector/fdc/design/modifications.pdf Frame Modification Work].
 +
-->

Revision as of 17:36, 25 March 2010

March 25, 2010 FDC meeting


Tentative Agenda

  1. Production space update off-site floor plans
  2. Electronics
    • threshold variations in the discriminator section of the pre-amps (Fernando) Fernando's pdf
    • PCB status
  3. Frame modification
    • cathode sandwich and wire frame
    • ground plane tests (leakage, tension)
  4. Wire winding update
    • IUCF phase 3 contract phase 3 budget
    • plans for wire winding upgrades in the summer
    • tension specs
  5. Full scale prototype tests
  6. Cathode frame redesign
  7. Other

Minutes

Participants: Lubomir, Eugene, Bill, Daniel, Glenn, Casey, Mark, Beni, Simon, Fernando

Production space update

Two options are being considered. Properties behind Office Depot (preferably "Minuteman Press") and properties around Middle Ground Blvd (at Blue Crab) . The rent price of the latter is half the one at Office Depot, but requires building a room inside the bay area. Our position is that he most promising for FDC construction that needs only minimal modifications is the "Minuteman press". We can share the bay area with SRF (John Hogan).

Electronics

- Fernando presented measurements comparing the discriminator part of the pre-amp cards. The worst card so far is showing ~30% variations (min - max range). The question was whether this is acceptable. We all agreed that we don't want to modify the design of the cards.


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