Difference between revisions of "Minutes-12-3-2015"

From GlueXWiki
Jump to: navigation, search
(Agenda)
Line 23: Line 23:
 
= Minutes =
 
= Minutes =
  
Participants: Curtis, Naomi, Mike (CMU), Sean (NU), Cody, Luke, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).
+
Participants: Naomi, Mike (CMU), Sean (NU), Cody, Luke, Dave, Nick, Simon, Beni, Eugene (at the end), and Lubomir (JLab).
  
 
== CDC update ==
 
== CDC update ==
  
- Nick found the broken wire and separated it from the HVB (see log entry above). He fixed one more channel by replacing the HVB card.  
+
- Mike showed plots with time-to-distance deformation corrections now WITH magnetic field. They look close to the Garfield predictions. Next step is to apply the corrections and look at the beam data also for different runs.  
  
- Mike is looking now at the beam data; will apply the same correction as with the cosmics to correct for the tube sagging.  
+
- Cody fixed several bugs in the firmware and updated the fADCs in the CDC crates only. The issues were found by Naomi: end of window algorithm fails if no peak was found, issues with the overflow bit when summing; and other. The plan is to have a cosmic run today/tonight with CDC to check the fixes. Cody also swapped two CDC modules.
  
 
== FDC update ==
 
== FDC update ==
  
- Lubomir showed latest results on the resolution studies. The resolutions improved gradually due to some residual corrections, better alignment, tracking and finally by using Mathieson/Simon's function when fitting strip clusters; first plot shows the different functions used. Cathode resolution (second plot): red - resolution along y from tracking; green - after subtracting the tracking contribution (assumed to be about 100 microns); blue - resolution estimated from reconstructing wire position. Need about 80 microns contribution to explain the difference (quadratically) between green and blue - may come from the extension of the avalanche along the wire. Wire resolution (third plot): red -reconstructed from tracking; green - after subtracting the tracking contribution of 100 microns. In summary: cathode resolution (along wires) ~120 microns; wire resolution ~110 microns (between 1 and 4.5 mm from the wire).
+
- Luke looked at the cosmic data with the FDC and updated the spreadsheet (linked above) with the problematic channels: green - channels that were not working before and now are OK, red - new bad channels, all the rest no change in the status. The green is more than the red meaning we have lower percentage of bad channels, which is of the order of 0.5%.
  
- We started preparing a document describing the tests with the spare package.
+
- Looking at the results with 55Fe source on the spare package Lubomir found that the gain at the wire closest to the source is factor of 2 lower than the gain on the side wires (first plot with 1700V/-0V, second with 1600V/-400V Ar/CO2 90/10). The averaged charge for each wire is normalized by moving the source away from the front window. The gain drops due to the high rates. Using a scope and lowering the threshold till the rate stopped depending on it, we measured with Luke rates of ~40kHz. In case of MIP in the standard cells we expect the same gain drop by a factor of two to happen at ~100kHz (ratio of primary electrons for (6keV photons)/(1cm MIP) is 230/90).
 +
 
 +
- The TRD test is ready to go (just need beam) - follow the link above. Sergey and Lubomir installed radiators with different thicknesses in front of the spare package (see picture above).  
  
 
== Electronics ==
 
== Electronics ==
  
- Lubomir and Luke finished the response function measurements for both FDC and CDC preamps. First two plots show typical response functions (from fADC125). Third plot: Max/Min absolute values of the response function vs the input charge  for both FDC and CDC. The linear range for the CDC is wider than for the FDC (in fADC125 units). Fourth plot: Max/Min ratio is constant for the CDC but goes down with the charge for the FDC. It is not clear why (saturation effects?) but helps to eliminate the ion tails, which is not the case for the CDC.
+
- Nick is going to look at the CDC LV module
 
+
- Lubomir also used a scope to measure the FDC preamp+cable response function (last plot). The gain is about 1.8mV/fC. When compared with the fADC amplitude it saturates in a different way, not clear why.
+
+
== CDC/FDC papers ==
+
 
+
- Beni created templates for the NIM papers.
+
  
 
== Other ==
 
== Other ==

Revision as of 16:15, 3 December 2015

December 3, 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 (Mike, Simon)
  2. FDC update
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering (Dave)
  5. Other