Difference between revisions of "Minutes-1-23-2014"

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= Agenda =
 
= Agenda =
−
# Installation [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01172014_3.JPG],[http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01172014_2.JPG],[http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01172014_1.JPG],[http://www.jlab.org/Hall-D/detector/fdc/installation/HV_FDC1_C4_HV2.png] (all)
+
# Installation [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01232014_1.JPG],[http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01232014_3.JPG] (all)
 
# Engineering (Bill)
 
# Engineering (Bill)
−
# Electronics (Chris, Nick)
+
# Electronics [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCinst01232014_2.JPG] (Chris, Nick)
−
# Mini-DAQ results [https://halldweb1.jlab.org/elog-halld/FDC FDC E-log] (Beni)
+
# Mini-DAQ results [https://halldweb.jlab.org/elog-halld/FDC FDC E-log] (Beni)
 
# Other
 
# Other
  
−
<!--
 
  
 
= Minutes =
 
= Minutes =
  
−
Participants: Eugene, Fernando, Dave, Nick, Chris, Simon, Bill, Beni, and Lubomir.
+
Participants: Eugene, Fernando, Dave, Nick, Chris, Simon, Beni, and Lubomir.
  
 
== Installation ==
 
== Installation ==
  
−
- The top two quadrants were cabled (see first three pictures attached); Mike Klopf was working till his last minute at JLab, to arrange the cables nicely and uniformly (first picture). Nick is almost done with routing the second quadrant to the electronics. Casey and Tina are working now on the bottom right quadrant and have cabled already two packages (second picture).  
+
- The third quadrant (down left) has been connected to the detector side (see pictures attached). To keep the cables flat on the mesh, Casey uses long zip ties; we want to make sure that at the inner side of the mesh (second picture) these ties do not touch the CDC. Starting Monday, Nick and Chris (with the help of Casey and Tina if needed) will start routing these quadrant below the platform to the electronics side. Before that, over the weekend, Beni will test the second half of the quadrant (packages 3 and 4) with the mini-DAQ.
  
−
- Discussions about the routing of the LV cables. They all have to run to the left side (looking downstream) and it is not clear yet how they will be attached to the face of the magnet in their final position. Therefore, Tom prefers to disconnect them from the LV panel during insertion and then route them again to the panel. Fernando, Bill and other disagree; Beni showed on a drawing how to route the bottom half in order to avoid disconnection from the panel. Lubomir discussed if the extra length of the big bundle at the top right cable tray is enough for the FDC insertion (third picture).
+
- The HV was stable at +2100V/-500V without any trips from last Thursday (1/16) till Tuesday (1/21). One HV channel has a current oscillating between 0.5 and 1 uA, indicating some small discharging every 10-15 min, but never trips. On Tuesday Lubomir increased it to +2200V/-500V and it was stable over the night for all the channels, except four channels where the negative HV had to be lowered by 100V to have it stable. On Wednesday morning suddenly all the positive HV channels were turned off and it is not clear how, because the lab was closed and there was nobody in the Hall. We suspect it was a power glitch, but then why the negative HV channels were still on. Beni suggested checking if the ROCs did restart at the same time which may suggest it was a power problem.  
  
−
- On Monday we changed the gas to 40/60 Ar/CO2 pre-mixed bottle. The flow was initially increased from 400 to 1000 sccpm (using another mass flow controller with 6000 sccpm range and another rotameter), but at this point the bubblers stopped bubbling: the same old story and we suspect again that somehow gas channels with high impedance are created, making connection from the bubble meniscus to the air. Finally the flow was set to 800 sccpm (200 sccpm per package) so that the bubblers can work.
+
- On Wednesday also the gas bottle was empty. Since there were no techs to crane a new bottle, Lubomir switched to another bottle used before which was empty by Thursday morning. It turned out that one bottle (Ar/CO2 40/60 pre-mixed) at 800 sccpm is good for four days. We decided with Tom to have always one extra, full bottle, craned on the platform, so that we can change the gas without the techs being there. Another option would be to mix the gas using a temporary gas system, but Eugene suggested we better use pre-mixed bottles till the final gas system is ready. Then, as Beni explained, the idea is to have 12 Ar bottles used at the same time (connected in one by the supplier). This is not the case for the CO2 bottles, but we will have many of them at the same time.
−
 
+
−
- Since Wednesday  nominal HV, +2100/-500V, has been set on all channels except one (fourth picture showing its current) with +2000/-500V and there were no trips for more than 24 hours. After the meeting that channel was also set to the nominal HV and is stable: '''all the HV channels are now operational at the nominal HV and gas mixture.'''
+
  
 
== Engineering ==
 
== Engineering ==
  
−
- On Wednesday morning we found the chiller off with an active alarm. It turned out that there was disruption in the chilled water supply for several minutes that most likely caused the chiller to fail. The top half of the LV channels were on at that night which increased the Fluorinert temperature to 27degC (as measured with the chiller when it was re-started). Everybody agrees that we need a hardware shutoff of the LV crate in case the chiller fails and this is urgent. Details, how to do this, were discussed at another meeting organized by Hovanes right after the FDC meeting.  
+
- Bill was transporting (that's why not at the meeting) the extra cathode mounted on the strong back to be scanned at a Williamsburg company. It turned out they don't have an optical CMM with these sizes, but suggested to contact the same company (New River Kinetics) at Richmond.
  
−
- Even if the chiller failed due to the water disruption, Bill wanted to make sure that the chiller itself didn't contribute to that. Dave measured the temperature difference of the water in/out of the chiller and it was 31degF. According to Bull this means we have ~0.5 GPM water flow, while it is recommended to be 1.3 GPM to have smaller temperature difference. Bill is looking for a flow meter to measure the actual water flow.     
 
−
 
−
- Gas system: Bill sent to Brooks one of each: mass flow controller, control unit and cable. Certainly there's a problem, most likely in the control unit. Other than that, most of the gas stuff is ready, still needs to be tested. So when we fix the flow controllers, the system can be used in principle with a manual control and using one bottle (of each, Ar and CO2) at a time. Because of the high flow we use now one bottle per week. According to Dave we expect the next gas delivery for Feb. 5 and we have a little more than one bottle in the moment. Again, we need to find a temporary solution till Feb. 5, either reducing the flow or flushing with Nitrogen and postponing the tests.
 
−
 
−
- Bill talked to Jim Dahlberg, but there are no results yet from the last survey!?
 
−
 
 
== Electronics ==
 
== Electronics ==
  
−
- Chris discussed again with Bill how to connect the ground cable. The problem is the cable is very thick with a big lug at the end that doesn't fit well on the ground plate attached to the packages.  
+
- Grounding: Fernando and Bill decided this morning to use the thick ground cable (4/0, green) only up to the face of the magnet, but then inside the magnet to the FDC to use thinner cable (2/0, orange) instead. The lug for the latter cable is small enough so that it can be attached to the ground plate along the packages. Fernando raised the question of grounding the mesh. Now it is attached to the FDC ground by two plates needed for the mechanical connection: one of them should be insulated while the other one should make electrical contact.
  
−
- Fernando proposed to use techs from Fast Electronics, since we lost three people working on the cabling. Eugene agreed.
+
- We discussed if the current through the LV cables (~2A per cable) inside the magnet can result in a force that can do some damage like disconnecting LV connectors. Fernando: the return current goes through the same cables, so the force should be zero. Eugene has a different practical experience seing LV cables moving inside the magnet in a CERN experiment.  
  
−
- Fernando: 13% of the fADC125s have problems in the moment. It means we can fully equip the FDC with modules which will happen soon.
+
- Chris: the adapter (a PCB) for the 3M connector at the signal cables, to be checked with a differential probe, will be ready next week.
  
−
- While testing the signals from the FDC we found several connectors at the detector side with broken locks which Chris fixed immediately, but also two bad connectors at the electronics side. The latter are more difficult to be fixed and Chris wants to do all the bad connectors at the same time when we test all the cables. Three more cables have one or two bad channels due to the conductive tape problems. In some cases one can fix them by re-seating the connector and bending the cooling tube, however sometimes this introduces new bad channels even in the neighboring cards. Therefore for the moment we will not attempt to fix such bad channels if they are only a few.
+
- On several LV connectors at the panel side some of the shield wires got disconnected from the connector (third picture). Nick proposed, when fixing these connectors) to pre-tin the shield wires so that they could not come out one of the connector by one as they did.  
  
 
== Mini-DAQ ==
 
== Mini-DAQ ==
  
−
- Beni presented first results from the mini-DAQ (E-log entry 123). If reading 9 fADC125 per crate the rate is ~6Hz defined by the code running on the ROC. It checks if there's something above a threshold, then all samples are written to a file. Since there's no external trigger, the probability to get a hit in the 800ns window is of the order of 10^-6; practically one can get on average 10 hits per channel for 24 hours, however for some channels (short strips) one gets only a few hits (second plot in the E-log). Beni showed also the hit multiplicity (third plot), indirectly indicating that we are looking at signals, not noise.  
+
- 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.
  
−
- Beni now has two crates with 9 fADCs each, that can be used for testing. The rest of the fADCs don't have firmware; Cody is working on loading the firmware via VME and when this is ready we can use all the fADC125s. Beni also got 6 ROCs so we can have all of them running at the same time. Practically such tests will be used to find bad channels, but testing the bad channels will better be done with a scope. Fernando promised to build a testing board, adapter between the cable connector and the differential probe.
+
== Other ==
  
−
-->
+
- Next week meeting, only, will be in B101.

Latest revision as of 00:08, 1 April 2015

January 23, 2014 FDC meeting

Agenda

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


Minutes

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

Installation

- The third quadrant (down left) has been connected to the detector side (see pictures attached). To keep the cables flat on the mesh, Casey uses long zip ties; we want to make sure that at the inner side of the mesh (second picture) these ties do not touch the CDC. Starting Monday, Nick and Chris (with the help of Casey and Tina if needed) will start routing these quadrant below the platform to the electronics side. Before that, over the weekend, Beni will test the second half of the quadrant (packages 3 and 4) with the mini-DAQ.

- The HV was stable at +2100V/-500V without any trips from last Thursday (1/16) till Tuesday (1/21). One HV channel has a current oscillating between 0.5 and 1 uA, indicating some small discharging every 10-15 min, but never trips. On Tuesday Lubomir increased it to +2200V/-500V and it was stable over the night for all the channels, except four channels where the negative HV had to be lowered by 100V to have it stable. On Wednesday morning suddenly all the positive HV channels were turned off and it is not clear how, because the lab was closed and there was nobody in the Hall. We suspect it was a power glitch, but then why the negative HV channels were still on. Beni suggested checking if the ROCs did restart at the same time which may suggest it was a power problem.

- On Wednesday also the gas bottle was empty. Since there were no techs to crane a new bottle, Lubomir switched to another bottle used before which was empty by Thursday morning. It turned out that one bottle (Ar/CO2 40/60 pre-mixed) at 800 sccpm is good for four days. We decided with Tom to have always one extra, full bottle, craned on the platform, so that we can change the gas without the techs being there. Another option would be to mix the gas using a temporary gas system, but Eugene suggested we better use pre-mixed bottles till the final gas system is ready. Then, as Beni explained, the idea is to have 12 Ar bottles used at the same time (connected in one by the supplier). This is not the case for the CO2 bottles, but we will have many of them at the same time.

Engineering

- Bill was transporting (that's why not at the meeting) the extra cathode mounted on the strong back to be scanned at a Williamsburg company. It turned out they don't have an optical CMM with these sizes, but suggested to contact the same company (New River Kinetics) at Richmond.

Electronics

- Grounding: Fernando and Bill decided this morning to use the thick ground cable (4/0, green) only up to the face of the magnet, but then inside the magnet to the FDC to use thinner cable (2/0, orange) instead. The lug for the latter cable is small enough so that it can be attached to the ground plate along the packages. Fernando raised the question of grounding the mesh. Now it is attached to the FDC ground by two plates needed for the mechanical connection: one of them should be insulated while the other one should make electrical contact.

- We discussed if the current through the LV cables (~2A per cable) inside the magnet can result in a force that can do some damage like disconnecting LV connectors. Fernando: the return current goes through the same cables, so the force should be zero. Eugene has a different practical experience seing LV cables moving inside the magnet in a CERN experiment.

- Chris: the adapter (a PCB) for the 3M connector at the signal cables, to be checked with a differential probe, will be ready next week.

- On several LV connectors at the panel side some of the shield wires got disconnected from the connector (third picture). Nick proposed, when fixing these connectors) to pre-tin the shield wires so that they could not come out one of the connector by one as they did.

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.

Other

- Next week meeting, only, will be in B101.

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