Difference between revisions of "Minutes-10-14-2010"

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== Engineering ==
 
== Engineering ==
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- Wire stringing: the pin bars were mounted on the granite table. Almost all the parts are ready. David got the ISA-USB
 
- Wire stringing: the pin bars were mounted on the granite table. Almost all the parts are ready. David got the ISA-USB
 
converter for the movement system, but has not tested yet. Bill got a PMT from Carl to be used as a sensor for automatic mapping of the wire positions. If the light on the PMT is too high, we would better use a photodiode. Fernando will help Bill with this.
 
converter for the movement system, but has not tested yet. Bill got a PMT from Carl to be used as a sensor for automatic mapping of the wire positions. If the light on the PMT is too high, we would better use a photodiode. Fernando will help Bill with this.
  
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- Vladimir Nelyubin check the wire tension with the new method: measured 70g, but but 100g. This is the first
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- Vladimir Nelyubin check the wire tension with the new method: measured 70g, instead of 100g used in the stringing. He will re-string the wires and repeat the measurements. Suspects friction between the wires and the rod when stringing. Concerning our procedure, he thinks for 20g tension that we will have, the pulley system will be helpful.  
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According to Bill: the strong-back has been machined ready to be put on the granite table. The pin bars are in the machine shop to be attached to the spacer bars. The mounts for the micrometers (that will be used to adjust the chamber position w.r.t. pin bars) was designed and will go to the machine shop today. David was working
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on the motion system: capable of 0.2 microns increment, good  repeatability, but needs more tests. He ordered ISA-USB converter to connect the stepper motor controller to a new computer. Bill and David are looking for a sensor to be used for automatic mapping of the wire positions.
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- According to Vladimir Nelyubin from UVA, they demonstrated that the proposed tension measurement system works. They used a functional generator, audio amplifier, transformer
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== Full-scale prototype  ==
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to produce +/-400V pulses in an electrode. The electrode was 15cm copper tape placed along the wire at 5mm distance. The wires were connected to ground. To generate vibrations they had to apply in addition some constant voltage ~1kV (it is not so clear why and has to be discussed further). The vibrations are visible and just visually one can identify
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the resonance frequency of the order of 200Hz with ~2Hz precision.
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- Lubomir re-visited the previous calculations (Gluex-doc 1431 v1) of the wire tensions. There, a formula used for proportional chambers, was used to calculate the critical tension below which uncontrollable oscillations will begin. In case of drift chambers, the oscillations are not a concern. Still, if we have 20g on the sense wires, there will be a sag of 40microns in the middle of the longest wire, which is good enough. If we want to have the same sag on the field wires the tension must be  8 times bigger (reflecting 8 times bigger linear density), or 160g as in the above document. If we had 80g, the distance between the field and sense wires in the middle would change by 40microns. Lubomir will run Garfield simulations to estimate the effect on the resolution, most likely it will be small. Based on this, Fernando and Eugene made remarks that we don't need a very good precision in the tension and maybe the pulley system is not needed.
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- Mathew Wright will do the ODH and flammability calculations for the argon/CO2/methane gas mixture. In this calculation one is allowed to separate the chamber volume from the gas bottle if we install a valve on the pipe in between.
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== Full-scale prototype  ==
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- Beni installed the fADC125 module and incorporated it in the CODA system successfully. He had to play with the trigger time to adjust the fADC125 window to the signals. Gerard: do we need to have the timing window programmable? Beni: later yes, but in the moment it's not needed. Beni is working now on the data analysis software.   
 
- Beni installed the fADC125 module and incorporated it in the CODA system successfully. He had to play with the trigger time to adjust the fADC125 window to the signals. Gerard: do we need to have the timing window programmable? Beni: later yes, but in the moment it's not needed. Beni is working now on the data analysis software.   

Revision as of 23:37, 14 October 2010

October 14, 2010 FDC meeting

Tentative Agenda

  1. Production
    • Blue Crab status
    • Frame production, lamination
  2. Electronics (Fernando, Chris, Roger)
    • Update on PCBs
    • Cathode foil procurement
  3. Engineering (Bill, David)
    • Wire stringing: fixtures, movement system
    • Other
  4. Full-scale prototype tests (Beni, Lubomir)
    • status of gas mixture studies
    • tests with fADC125
  5. Other


Minutes

Participants: Eugene, Fernando, Bill, Chris, Roger, Casey, Mark, Glenn, and Lubomir.

Production

- At Blue Crab now we occupy some space at the far corner not to interfere with the installation work there. We have there two granite tables and one round. Casey will order two more round tables. Need additional temporary light. AC for the whole building is coming soon. JLab internet connection and two plain phones will be installed in the office.

- Five wire frames were laminated with Rohacell rings and sent back to the company for flat cut. Last two laminated at Blue Crab. Five new frames will come soon. Two new Rohacell rings are ready.

Electronics

- The first article populated PCBs will be at JLab next week. They will be checked, channel by channel, and will be ready by the end of October. Then the first PCB ring will be glued, most likely in 126. By the end of November we will have all the PCBs ready. They will be stored in F117.

- No news from the procurement about companies (other than Allflex) interested in the cathode production. The deadline was Oct.13. As Fernando promised before, he will take care of the procurement (not a sole source!) of the rigid-flex. Fernando and Roger will contact Allflex for the details of the rigid-flex production.

- Fernando submitted a PR for the mini HV cables.

Engineering

- Wire stringing: the pin bars were mounted on the granite table. Almost all the parts are ready. David got the ISA-USB converter for the movement system, but has not tested yet. Bill got a PMT from Carl to be used as a sensor for automatic mapping of the wire positions. If the light on the PMT is too high, we would better use a photodiode. Fernando will help Bill with this.

- Vladimir Nelyubin check the wire tension with the new method: measured 70g, instead of 100g used in the stringing. He will re-string the wires and repeat the measurements. Suspects friction between the wires and the rod when stringing. Concerning our procedure, he thinks for 20g tension that we will have, the pulley system will be helpful.

Full-scale prototype

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