Latest revision as of 12:33, 17 September 2015

September 10, 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. CDC update
   • CDC response to 55Fe and 90Sr sources logbook entry
   • Electronics response functions
   • The sag saga: maximum docas at center of CDC
2. FDC update
   • studies with 90Sr and 55Fe on spare package: [2],[3], [4]
3. Electronics
4. Engineering
5. Other

Minutes

Participants: Curtis, Naomi (CMU), Sean (NU), Fernando, Eugene, Luke, Beni, Dave, Marc (Mcmullen), Nick, Simon, Sergey and Lubomir (JLab).

Other

- Curtis and Naomi discussed the tracking session for the coming collaboration meeting. So far two reports were requested, FDC (Lubomir) and tracking (Simon) update; expect one more about the CDC, to be discussed later.

CDC update

- Simon showed a map of the CDC (attached above) with the maximum drift distances, as seen by tracks coming from the target. Shown is the distance at the middle of the straw assuming sagging. One can see that certainly not all offsets can be related to gravity, so most likely there are tube deformations. Discussions how to parametrize the deformation and the time-to-distance function: most likely it is enough to use one function/table with extended distances (Curtis). Suggestions: to look along z, also to plot the asymmetry and sum in positive/negative phi.

- Scope pictures of signals from 55Fe source on one CDC straw shown the logbook link. When using adapter card without termination we saw ~20% reflection at 200 ns from the cable (18m). The reflections disappear when we used a terminated adapter card. However, it means that there's reflection not only at the adapter side of the cable but also at the HVB side - Fernando will look into that.

FDC update

- Scope picture of the drift times in the two thick chambers of the spare package shown above, using 90Sr source and a trigger made on the scope by coincidence of two parallel wires from the two chambers. The max drift times for the first cell is about 9 usec, while Garfield predicts ~6 usec. The next two plots show the total charge vs max amplitude with 55Fe source: it demonstrates that with 90/10 gas mixture one can see the argon and escape peaks, also for big drift times they are broader (in time) possibly due to diffusion.