Revision as of 16:10, 20 June 2013

June 20, 2013 FDC meeting

Agenda

1. Production spare package installed, and the people around it
   • Spare package tests (Vlad)
   • Thicker cell results (Lubomir) [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]
2. Engineering (Bill)
3. Electronics (Chris, Nick)
4. Full electronics test FDC E-log (Beni)
5. Other

Minutes

Participants: Bill, Beni, Simon, Vlad, and Lubomir. Due to the PAC, magnet test going on at the same time, Wiener people coming on site, the turnout was low for this meeting. The meeting was in A110.

Production

- End of last week we installed the last cell of the last package (see the photos of the package and the happy people around it, attached above). Vlad tested the new cells and found no problems. The top two cell have 3.5 instead of 0.5cm spacer ring. When using iron source Vlad had to increase the HV by 100V to see approximately the same amplitudes as from the regular cells. Very interestingly the last two cells showed very low dark current ~20-30nA, compared to 200-800nA for the other cells. We are not sure why, just because these were the last two wire frames produced, or there's something else related to the special geometry of the cells.

- First signals on the scope with definitely visible individual clusters over a very long drift time (up to 15 usec) are attached above. We some minimal grounding we were able to lower the noise to <5mV. At the same time we increased the gas gain to about 2-3 x 10^5 by going up with the HV up to 2450/-500V ! Amazingly the two cells were stable at this HV at least for several hours. Having such gas gain we were able to clearly see (see scope pictures above) individual electrons corresponding to ~20-30 mV signal. On average we have two electrons per cluster, and really we see some single peaks, and some double/triple peaks separated due to the diffusion.

- Plans: on Monday we will take the two gusset rings from the spare package since we will need them for a week to build the package spacers. For that, first we will replace the top gusset with a Lexan sheet, then will take the package out of the mounting table and put it upside down using some strong-back. Then we will replace the bottom gusset. After we are done with the spacers we will re-install the gusset rings in the same way. The spare package will go for testing in 126 after we are done with the third package there. The spacers will be installed between the packages and then we will do the practicing with the mock-up.

Engineering

- Bill started working on the fixture for the scintillators needed at the Hall for triggering: it is not a problem at all and will consists of unistruts along the cart attached to the cart frame.

- Bill was asked by Bruce Lenzer (suggested by Glen) to include the mock-up cabling in their QA plan, since this will verify that the cable density is correct and that there's enough space to the CDC and BCAL. Bill will write a short report after this exercise.

Full electronics tests

- Beni now has the software to sparsify the data from the fADC in the ROC processors. Now he is taking long runs over the night and some results are shown in the E-log entries 110, 111.