Revision as of 18:04, 25 April 2013

April 25, 2013 FDC meeting

Agenda

1. Production Construction Tracking
   • Third package status
   • Spare package
2. Corrosion tests at MePhi: results, [1], [2], [3], [4], [5], [6], [7]
   • Discoloration in the bottom cathode of package #3 [8], [9], [10], [11]
3. Installation (Lubomir, Bill)
   • FDC installation document
   • Practicing at Blue Crab
4. Engineering (Bill)
   • Cooling system tests [12], [13], [14]
5. Electronics (Chris, Nick)
6. Full electronics tests FDC E-log (Beni)
7. Other

Minutes

Participants: Casey, Bill, Chris, Nick, Simon, Beni, Fernando, and Lubomir.

Production

- Third package: Casey installed the manifolds without tightening the compression fittings, but as it turned out from the cooling system tests (see below), we have to check the manifolds with high pressure before finishing the installation.

- Spare package installation: installation table is ready, Casey made the threaded rods that are longer by 6cm for this package. Next week (after we are done with the third package) we will start putting O-rings on two spacer rings and one type-1 cathode. The plan is to install two cells at once. The last two cells will be with the two thicker spacer rings, to be used to test the cluster counting technique. It turned out it that we can use the standard gas (40/60) for these studies instead of the Helium mixture. Due to the lower drift velocity with the standard gas one can get a good cluster separation, just we will have up to ~20 microsec drift time, compared to ~7 microsec with the Helium gas.

Corrosion tests at MePhi

- Vlad sent latest results attached above with pictures. The three Viton samples (one Viton and two Viton+Apiezon) failed at the same time 70 days after the start of the experiment. The two EPDM samples failed within the first 24 hours. Only one Viton sample was still OK, but we decided to open the set-up. Vlad found that the two EPDM samples failed due to the copper corrosion under the O-rings, while all the others had problems in the soldering. Depending on the assumptions for the activation energy, this test gives between 3 and 5 years minimum live time. Vlad prepared six EPDM samples for the next test to be performed at 67degC to estimate the activation energy.

- Hopefully not related to the corrosion problem, we again observed discoloration (pictures attached above) on the bottom cathode (type-3) of package #3 when we opened it to work on the HV problem there. There, of course, we had Viton + Apiezon. After cleaning with alcohol most of the black stuff was removed but some traces remained as seen on the last picture. The cathode was tested and no problems were found.

Installation

- We decided with Fernando to have the crates installed in the racks before we start the cabling. The fADC125 modules will be tested separately and then installed in the crates. The cables will be installed in such a way so that they can be connected to each of the three connectors on the module when it becomes available. Thus, when testing a certain package, even if we don't have the modules for that package in place, we can insert other modules there and do the test. The drawback is of course that you test the modules not together with the crate where they are supposed to be used, but this will speed up the FDC installation.

- Cable practicing: Bill will look if the mesh cylinder attachment needs to be modified. We decided to use the real packages (we will have at least three at Blue Crab) for this exercise. The main concern is the strain relief for the cables: where they have to be attached to? Bill: the main strain relief comes from the attachment to the mesh; in between the packages we will use carbon rods tightened to the outer side of the cooling tubes, that will be used to support the cables there. Since the copper tubes are supported mostly by the preamps (but also by the manifolds) we want to make sure the load on the preamps is small enough. That's why we want to prototype all this configuration. If necessary, we can add support from the frame in the way the manifolds are supported, but this will add additional material.

Engineering

- Cooling system test: the testing set-up was finished at the beginning of the week and this morning we put Fluorinert in the chiller, but immediately after turning it on Fluorinert blew off at several places on the front three or four manifolds. There visible cracks seen in the pictures attached. The manifolds are made out of Norel and the first batch was tested at 230psi with water, while we had 100psi in this test. It's not clear exactly what is the cause for the manifold crack: just came from another production batch with the crack already, or caused by tightening the fittings (not likely), or something that shows up only when using Fluorinert, not with water? In any case a decision has been made to use make the manifolds out of aluminum.

Electronics

- Fernando: by the end of next week we will have 34 fADC125 available. Now the communication with the company producing the fADCs is much better. The plan for the mass production is to have 45 units beginning of May and then receiving 45 each two weeks till the end of June. The production of the 54 F1TDC(V3) is finished, 43 will go to UMass for testing. By the end of May we will have all the TDCs here at JLab.

Full electronics tests

- The third package will be ready for moving to 126 by the beginning of next week. Will have 30 fADC125 by the end of next week. Will need 132 signal cables that we decided to label with the original labels, and 33 LV cables (not labeled); all this we will get from Nick. After testing the chiller at the beginning of the next week we can directly hook it up to the manifolds of the package. In summary: we will have all the infrastructure needed for the test by the end of next week, so we should plan moving the package to 126 by that time.

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