Minutes-1-30-2014

January 30, 2014 FDC meeting

Agenda

1. Installation [1],[2] (all)
2. Engineering December 2013 survey
3. Electronics (Chris, Nick)
4. Mini-DAQ results FDC E-log (Beni)
5. Other

Minutes

Participants: Fernando, Dave, Nick, Chris, Simon, Beni, Eugene, and Lubomir.

Installation

- Casey, Tina and Anatoly finished cabling the FDC at the detector side and it looks nice (first picture attached). On Tuesday the platform on the right side was opened and today Nick and Chris started routing the right bottom quadrant to the electronics. They are done with package #4 working now on #3.

- HV: was stable since the beginning of the week at +2200V/-500V, except for 6 channels at +2200/-450V and three channels at +2200/-500V, out of 96 total number of HV channels. Such change of the field voltage on these 9 channels affects the biggest drift times/distances where the resolution is in any case poor, so the average track resolution will not be affected. Note also that +2200V is the upper limit of the HV range and we may not need to be there.

- Gas: since Tuesday we are running gas at 400ccpm (according to the mass flow controller set point) compared to 800ccpm before, because we don't have more bottles and the next ones are expected to come next week. This morning somebody working at upstream face of the magnet, pulled the exhaust gas line and we found (also in the morning) the bubbler and a "quick-connect" connector disconnected. As a result the pressure went down to ~20Pa from ~60Pa. The pressure recovered in about two hours. At the end of last week one of the bubblers stopped bubbling and the pressure started increasing (as usual), however, after inserting a tube at the output of the bubbler going inside the oil (second picture attached) it started bubbling again with high rate and the bubbling is very stable since then. Dave proposed to put a plastic shield at the downstream side of the FDC to protect the gas and other FDC stuff there. Also expect that the test of the BCAL water cooling system which is next to the FDC, will start next week (need an umbrella!).

Engineering

Bill was busy at another meeting, but he communicated with Lubomir:

- We have now the report (attached) of the survey of the 16 reflectors done in December when the FDC was inside the magnet. In z-direction, the deviations from the nominal are not more than ~0.5 mm resulting of a pitch and yaw less than 0.4 mrad. Such deviations will have just a little contribution to the resolution even if not corrected for. It would be interesting to compare with the survey results when the FDC was outside of the magnet.

- Bill received an answer from BROOKS: the mass flow controllers are to be blamed and now both the set and the read-out values are different from the actual flow. Beni: all the mass flow controllers that have been re-calibrated in the second batch, 7 in total, have the same problem. We have to send them for fixing a.s.a.p., still we want to keep one to be used in the temporary gas system that we have now for the FDC. The two mass flow controllers that have been re-calibrated first, are working fine (now in EEL126).

- Bill found a company (Hexagon Metrology) in Charlotte, NC that has the machine (MCC) to scan the cathode. Bill is arranging a trip to there with the cathode to do the measurement in the next few weeks.

Electronics

- The adapter (a PCB) from the 3M connector (that is on the signal cables) to the differential probe is ready. We started immediately using it for testing the cables with a scope, instead of the shaper board that sees only 16 channels and has additional shaping.

- For the next meeting Lubomir will make a list of all the problematic cables/connectors/pre-amps as identified with the scope testing or with the mini-DAQ.

- Since we will have all the cables routed to the right racks we will start at the same time plugging the cables to the modules. Not all the modules are in place, but Nick and Chris will install the missing modules (now Cody has them) and Fernando agreed.

- The grounding cable is ready, needs to be attached to the FDC.

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Mini-DAQ

- Beni presented his results from the mini-DAQ (E-log entry 125) for the wire readout. Since the TDCs work very fast one can get high statistics result in about 2 hours as shown on the plot. For the strips the readout is very slow, the fADC125 firmware for the fast readout is not ready yet and there's no zero suppression. Beni showed results (E-log entry 124) taken over the long weekend. One can see some hot channels and some missing. Lubomir looked with a scope at all the problematic channels and didn't see high rate in the hot channels; the missing channels were most likely due to problems with the 3M connector; Chris will look at this.

- Can we use the mini-DAQ as it is, without external trigger, for the final FDC test? Everybody agrees that if the fast readout is not ready we can't. Even if it is ready we still will not be able to have timing spectra (like drift times) without external trigger that may be needed the check for example if the negative HV is OK. However (Eugene) with the chambers in a vertical position it is not clear if the drift time spectra will make sense.