Difference between revisions of "Minutes-2-5-2015"

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== FDC update ==
 
== FDC update ==
  
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- We discussed again the structures seen in the difference between the cathode reconstructed and the nominal wire position as a function of x and y - 2d plots and x-projections for all the cells in package 3 are attached. It is amazing, you see the same structure in all the cells, the projections can be fitted with almost the same sin function with an amplitude of ~200 microns. So far, no idea what is it.
  
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- Lubomir showed results for strip resolutions after aligning one package:  estimated from tracking it is ~250 microns, while from reconstructing the wire position it should be ~170 microns. This may mean that better alignment of all the cells is needed. At the same time it may be related to some structures seen in the last plot above: the difference between the cathode reconstructed and the nominal wire position as a function of x and y averaged over all the hits for each 2d-point. The dips and peaks on the plot rage by up to 200 microns and this structure is very similar for all the cells in the package. It's impossible to have such deviations in the wire positions, so it must be coming from the strip positions; needs further investigation.   
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- Vlad recalled that 2.5 years ago he put O-ring/cathode foil samples in the old Simon's chamber prototype, to study the corrosion. The O-rings were pressed against the foils in the chamber grooves and the chamber was stored in EEL126. From the pictures linked above one can see that the sample with the EPDM O-ring has dark spots and some damage of the copper layer, while the sample with Viton O-rings (that we used in the FDC) looks almost unchanged.  
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- Wire resolution: estimated from tracking the over-all resolution is ~200 microns. Plotted as a function of the distance to the wire it is somewhat worse than the results with cosmics at EEL126 for small distances. This may indicate worse timing resolution coming from t0 uncertainties when using the start counter.
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== Electronics ==
 
== Electronics ==
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- Fernando: CDC is ready for testing, all HVBs have been installed and the HV cables re-routed. However, the noise is still there. CAEN finished the prototype of the chassis with the HV filter. It will be tested here and then decide about the production.
 
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- Cody installed the latest f125 firmware and started tests: it works as expected, except in block mode when the triggers are too close (Beni). Issues with some of the channels turned out to be software problem: bad DAC values.
 
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- One of the signal cables on the CDC turned out to be shorter than the rest, that's why the signals from this card were coming earlier. 
 
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== Engineering ==
 
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- Dave: the thremocouple for the alcohol bubbler is now working and the temperature is sent as an EPICS variable. The power switch-off box for the chiller will be tested with a motor. The chiller has been received by the company and soon they will have an estimate about the time needed for the repair.
 
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Revision as of 19:25, 6 February 2015

February 5, 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 puzzle
    • gain for different wire diameters [2]
  2. CDC update (Mike)
  3. FDC update (Lubomir, Vlad)
  4. Electronics (Fernando, Cody)
  5. Engineering (Dave)
  6. Other

Minutes

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

Gas puzzle

- CO2 sensor sent to the company for repair; will have it next week. Initially, it will be connected to a laptop (serial to USB) with the GASLAB software. For the spring run we want to connect it to a terminal server, but then we need software to put the information in epics (Hovanes).

- Using Garfield, Lubomir compared the gains in the CDC with the two wire diameters, 17.8 um used in the prototype and 20 um used in the CDC. Plot of the response of simulated 55Fe source is linked above - about 70% increase in the gain from 20 to 17.8 um wire, when using Ar/CO2/propanol 58/42/0.33 gas mixture. Naomi: with the standard gas 50/50 they have seen just 10% increase. Lubomir will do simulations with the standard gas, as well.

- Gain measurements with 55Fe source will be done with both, the FDC spare package (standard 40/60 gas) and the FDC in the Hall with whatever gas is there, to make sure we understand the gas mixtures and the Garfield simulations. The spare package in EEL126 is being flushed with gas since last Friday. Beni is recovering the DAQ we used in 126, but there are some issues yet related to the new firmware.

CDC update

- Mike is working on the CDC efficiency. CDC is ready for taking data with the BCAL cosmic trigger, hopefully this weekend.

FDC update

- We discussed again the structures seen in the difference between the cathode reconstructed and the nominal wire position as a function of x and y - 2d plots and x-projections for all the cells in package 3 are attached. It is amazing, you see the same structure in all the cells, the projections can be fitted with almost the same sin function with an amplitude of ~200 microns. So far, no idea what is it.

- Vlad recalled that 2.5 years ago he put O-ring/cathode foil samples in the old Simon's chamber prototype, to study the corrosion. The O-rings were pressed against the foils in the chamber grooves and the chamber was stored in EEL126. From the pictures linked above one can see that the sample with the EPDM O-ring has dark spots and some damage of the copper layer, while the sample with Viton O-rings (that we used in the FDC) looks almost unchanged.

Electronics

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