Minutes-4-25-2013

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 cracks: just came from another production batch with the cracks already, or caused by tightening the fittings, or something that shows up only when using Fluorinert, not water? In any case a decision has been made to make the manifolds out of aluminum. Bill already ordered the parts after the meeting. Four manifolds will be ready in a week and can be put on the third package. At the same time we will test all the manifolds for cracks at Blue Crab using CO2.

Electronics

- Fernando: Cody is doing full tests of the fADC125 modules including the interface to the crate. Cody will not be here by the beginning of the next week, therefore we can have 30+ modules at the end of next week. Beni got 3 modules to play with.

Full electronics tests

- Decided to postpone the transportation of the third package to JLab, will do it next week after the manifolds are tested and installed and when we will have the fADC125s.

- Beni: the CAEN HV module that failed in 126 (all the channels went up to the hardware limit) was tested by Nick in 117 without load and was working properly.