October 27,2010 Tracking CDC/FDC
Contents
Meeting Time and Place
Wednesday Ocyober 27, 2010 at 11:00am At Jefferson Lab, the meeting will be held in ARC 428
Connections
To connect from the outside, please use ESNET
1.) ESNET: 8542553
2.) Phone:
+1-800-377-8846 : US
+1-888-276-7715 : Canada
+1-302-709-8424 : International
then enter participant code: 77438230# (remember the "#")
Agenda
- Announcements
- FDC Update logbook
- CDC Update [1]
- CDC Flow rate
- CDC heated gas measurements Heated_gas_measurements
Minutes
Participants: Curtis, Naomi, Eugene, Beni, Simon, and Lubomir.
FDC Update
Production
Cathode foil contract awarded and we are expecting the first article in a month. Wire frame lamination with Rohacell rings is going well: 15 frames done. The next step in the production is fly cutting the Rohacell, to be done at the Vision machine shop. First article populated PCBs received. At the beginning, they couldn't hold voltage above 1500V because of the residual flux under the HV capacitors. Problem fixed after cleaning.
Full-scale prototype tests
Gas gain measurements/calculations done in three different ways (page 530 FDC logbook) using 55Fe source. First, measuring the total current and the total rate on the wires. Second, by simulating the signals with Garfield and comparing them with the measurements. Third, using Garfield to calculate the Townsend coefficients. The first two methods give very similar results.
Comparing the 55Fe amplitude spectra (page 527) for two gas mixtures, 90/10% and 40/60% Ar/CO2, shows that the widths of the Ar peak are very similar, while CO2 contributes a tail with a bump at lower amplitudes.
CDC Update
CDC Construction
The CDC review last week went well.
We have a few straws dry-fitted into the CDC and the technicians have been practising stringing and crimping with these straws, they have come up with some improvements to the stringing procedure (using a magnetic probe for needle reception).
We still need the crimper drawings from Steve Cristo - Beni will check with Tim - and some new wire.
ADC125
The new fADC is installed and apparently working through CODA but the readout needs some more software work. Naomi will talk to Beni about this. It also needs some hardware ingenuity to make up a trigger for Fe55 measurements.
Flow rate
The measurements on Flow rate were discussed, in particular what causes the highest amplitude peak at 2050V and above, and why the flow rate affects the pulse amplitude.
Naomi will:
remove the small flowmeter between the gas mixer and the CDC prototype;
uncollimate the Fe55 source (to get a higher rate, presently 27 counts/sec);
put premixed gas through one channel of the mixer;
add event pictures to the wiki.
CDC heated gas measurements
Brent Driscoll's results from heating the CDC prototype were presented Heated_gas_measurements
