Minutes-3-12-2015

March 12, 2015 FDC+CDC meeting

Connection

1. Instructions for Bluejeans meeting connection
2. FDC meeting ID: 290664653
3. To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.

Agenda

1. Gas issues
   • CO2 monitoring [2],[3]
   • FDC gain measurements
2. CDC update (Mike)
3. FDC update [4], [5] (Lubomir)
4. Electronics (Fernando, Cody, Chris, Nick)
5. Engineering (Dave)
6. Other

Minutes

Participants: Curtis, Naomi (CMU), Sean (NU), Fernando, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).

Gas issues

- CO2 was monitored for another 4 days: the first plot is with a correction function with a power of 2.4, second with 1.4, as explained in the previous meeting. First, the sensor was connected to the CDC for one day(Thursday-Friday), then moved to EEl126. There the bottle was almost empty and as it turned out the CO2 was lower than 60%. On Sunday the bottle was replaced and by Tuesday the values were close to 60%. At that time the fan failed - as the instructions say it has 1000h life and we were using it one month already. We didn't learn a lot from these measurements, except that the change of the gas factor, done a week ago, showed almost no effect (0.5-1% as expected) on the gas mixture. If we want to continue monitoring CO2 we need to buy another pump ($200) that will work for another month, or try to find a better pump. Beni suggested using the pump that Bill made for the O2 measurements.

- Beni did different changes in the settings of the mass flow controllers used for the CDC mixing and was looking at the maximum drift time. Changing the gas factor didn't show any difference (within 1%). Then he changed the controller mode from "mixing" to independent flow control and he found a slight change in the drift time but in the opposite direction, i.e. shorter. Next steps: change the gas factors to 1 to see if it will make any difference. Beni suspects something is wrong with the controller boxes.

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