July 18, 2012 Tracking CDC/FDC

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Meeting Time and Place

Wednesday July 18, 2012 at 11:00am At Jefferson Lab, the meeting will be held in F326

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Hardware Agenda

  1. Announcements
  2. FDC Update
    1. Gas mixture choice: Media:GasCompilation.pdf
  3. CDC Update
    1. Prototype dE/dx CDC_signal_integration_new
  4. TDR Update
  5. Calibrations
    1. CDC prototype first attempt at virtual wire wiggling CDC_wiggle_wire_positions

Minutes

Participants: Curtis, Naomi, Beni, Simon, Lubomir, Tim, Mark

  1. FDC Update
    1. Top two cells of the fourth package showed high dark currents. The problem comes from HV traces on the back of the PCBs that are against the Rohacell.
    2. We are looking also at the spare wire frames to find better replacements. At the same we are submitting PRs for four sets of PCBs and g10 frames to build four more wire frames. Most likely, we will close the fourth package as it is with four cells, till we make the new wire frames, and continue with the refurbishment of the first and second packages.
    3. Beni made progress with the two-crate DAQ for the cosmic tests at 126, still there are some issues with the Linux libraries.
    4. Gas mixture choice: Media:GasCompilation.pdf Lubomir presented this. An organic gas could be quite useful for the FDC, ethane and isobutane look promising, offering higher gas gain for the same or lower HV and also suppressing afterpulses. Beni has done some research on what gas mixtures were used in the past and what aging effects were observed when operating the chambers in radiation environments. There seem to be no predominant ageing observed in chambers that could be attributed to the use of isobutane alone. The CMS drift chambers used a gas mix of CO2/Ar with 10% ethane and in radiation tests showed no degradation of the operating parameters, however they found small deposits on the wires and cathode strips visible through a microscope. The CDC team are not planning to use an organic gas initially, our gas gain is limited by the electronics. The current plan is to design the system for 3 gases but initially implement 2 only. The addition of a flammable gas means that the exhaust gas will have to be vented outside the hall, not into it. Also there could be problems if the detectors leak.
  2. CDC Update
    1. The new nonmagnetic wire arrived but did not match the sample sent earlier, the new wire's dielectric melts when the wires are soldered. A replacement batch is expected early next week. Until then the team are continuing to make hookup wires from the original (slightly magnetic) wire.
    2. Wiring and testing are proceeding smoothly, currently working on row F.
    3. Gary has started designing a transport cart (with pneumatic tires) to support the CDC whilst it is moved from CMU to JLab.
    4. Prototype dE/dx CDC_signal_integration_new was discussed, in particular, using signal amplitude for dE/dx, as it seems to scale nicely with track length. Lubomir offered to run some Garfield calculations to model the first amplitude peak for different particles.
  3. TDR Update
    1. This is rising nearer the top of the to-do list. A little more progress has been made recently.
  4. Calibrations
    1. CDC prototype first attempt at virtual wire wiggling CDC_wiggle_wire_positions was discussed. Mark suggested looking at left/right differences in residuals to distinguish time errors from position errors.