Difference between revisions of "Minutes-7-3-2014"
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- Fernando suspects the noise may come from the CDC itself, since it depends on the HV, and suggested increasing the CO2 content while keeping the same HV; the idea is to exclude the HV modules as a source of the noise. Eugene/Naomi: same effect will be if decrease/increase the HV by few hundred volts. Also it's difficult to explain with gas discharges the correlation we see in the noise (see plots from the last meeting). In any case, first Mike will study systematically where on the CDC we see the noise. | - Fernando suspects the noise may come from the CDC itself, since it depends on the HV, and suggested increasing the CO2 content while keeping the same HV; the idea is to exclude the HV modules as a source of the noise. Eugene/Naomi: same effect will be if decrease/increase the HV by few hundred volts. Also it's difficult to explain with gas discharges the correlation we see in the noise (see plots from the last meeting). In any case, first Mike will study systematically where on the CDC we see the noise. | ||
| − | - Lubomir | + | - Lubomir looked with a scope on the FDC and found noise with very similar pattern on several special channels. That was on the most upstream cathodes in the first and second package, but not in the other two, and always in cards that have both long and short strips (more susceptible to noise). It may indicate that the noise comes from the CDC or the mesh but one has to study this more systematically. |
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== Electronics == | == Electronics == | ||
| − | - | + | - Fernando: two CAEN modules back from repair |
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== Engineering == | == Engineering == | ||
Revision as of 17:20, 3 July 2014
July 3, 2014 FDC+CDC meeting
Agenda
- Commissioning plans
- Gas system
- DAQ (Beni)
- CDC status (Beni)
- FDC status (Lubomir)
- Electronics (Chris, Nick)
- Engineering (Bill)
- Other
Instructions for Bluejeans meeting connection
FDC meeting ID: 290664653
Minutes
Participants: Naomi (CMU), Beni, Dave, Chris, Mike, Simon, Fernando, Eugene, Glenn, and Lubomir (JLab).
Readiness review
- Drafts (very preliminary) for the CDC and FDC commissioning were prepared for the readiness review (page linked above). For the FDC the plan so far is to use two gas mixtures, 90/10 and 40/60, the first one is better for the alignment. The target position(s) and turning on/off the magnetic field needs to be coordinated.
Gas system
- Last Friday, at ~8am, the power in the gas room was turned off for ~15 min due to a planned electrical work there. After turning it ON, the setting in the gas control panel were wrong (40mA, while the range is 4-20mA). As a result: (1) the flow was doubled and (2) the PLS didn't turned OFF the flow controllers when the mixing tanks reached 12psi. Soon the pressure reached 15psi and the two relief valves were continuously engaged for some time.
- After the meeting we installed an UPS (in preparation for the holiday weekend) there. Dave will contact the company to find a solution, at least to change the default settings to what we need.
DAQ
- Beni: can read now all the 18 crates (CDC+FDC). Sometimes DAQ crashes fatally, so that you have to reboot the computer (suspect InfiniBand). Also somehow the bios on gluon51 failed; will be replaced.
CDC noise
- Fernando suspects the noise may come from the CDC itself, since it depends on the HV, and suggested increasing the CO2 content while keeping the same HV; the idea is to exclude the HV modules as a source of the noise. Eugene/Naomi: same effect will be if decrease/increase the HV by few hundred volts. Also it's difficult to explain with gas discharges the correlation we see in the noise (see plots from the last meeting). In any case, first Mike will study systematically where on the CDC we see the noise.
- Lubomir looked with a scope on the FDC and found noise with very similar pattern on several special channels. That was on the most upstream cathodes in the first and second package, but not in the other two, and always in cards that have both long and short strips (more susceptible to noise). It may indicate that the noise comes from the CDC or the mesh but one has to study this more systematically.
