Revision as of 14:34, 28 August 2015

August 27, 2015 Drift Chamber meeting

Connection

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

Agenda

1. Electronics
   • CDC/FDC noise studies (Fernando) [2], [3],[4],[5]
2. CDC update (Mike, Simon, Beni)
3. FDC update (Luke,Lubomir)
   • fall2014 vs spring2015 offsets
   • Tagger Tests with Fe source: [6][7][8]
4. Engineering
5. Other

Minutes

Participants: Curtis, Mike, Naomi (CMU), Fernando, Eugene, Luke, Beni, Dave, Chris, Nick, Simon, Sergey and Lubomir (JLab).

Electronics

- Fernando studied the noise on the CDC and FDC together using two differential probes: see scope pictures linked in the agenda. First picture shows the noise levels in the two detectors are similar; FDC looks better but not by a lot. The second and third pictures show typical cosmic signals with correct timing. Last plot discussions - occasionally there are long tails in the CDC signals (~5 usec). The signals are still low enough (~100mV) so this is not a saturation effect (Fernando). Most likely it comes from ion tails (Lubomir), however it is not clear why it happens mostly in the CDC, is the ion-cancellation different in the two detectors?

- Nick: all "noise-reducing" elements from the CDC were removed. Tim is informed about that but needs to decide about the installation of an additional Al-foil target before inserting the target back. Nick replaced one LV module in the CDC; it was giving high current without any load. This is the second problematic LV module, the first one had different issue.

- The PR for 100 spare pre-amps was approved.

CDC update

- Simon continues to study the tube deformations using beam data. So far he checked rings 1 to 7 and 13. Ring 7 (stereo) looks worse and there's a straw with more than 1mm deformation.

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Electronics

- Eugene reminded about the deadlines for the end of the FY15. The PR for the 100 spare pre-amps is out.

FDC update

- Alignment offsets for the spring run different by up to 300 microns from the ones in the fall. Most likely this is due to the bias in the fall trigger.

- Using 55Fe source on the 4.5mm-thick cell results in very broad (in time) argon peak. The max drift time for the 40/60 gas is huge, ~20 microseconds which, at least partially, may explain this effect to be related to the longitudinal diffusion. Conclusion: need faster gas for the TRD test this fall, most likely 90/10 Ar/CO2.

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