April 11, 2012 Tracking CDC/FDC

Meeting Time and Place

Wednesday April 11, 2012 at 11:00am At Jefferson Lab, the meeting will be held in F326

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Hardware Agenda

1. Announcements
2. FDC Update oxygen studies, logbook
3. CDC Update
   1. Construction Update File:Wiremap.pdf
   2. Cosmic Calibration of the Chamber
   3. Prototype CDC_prototype_more_on_timing_3
4. TDR Update

Tracking Software Agenda

1. Announcements.
2. Summary of current work on tracking.
3. Where we need to focus work (Discussion)?

Hardware Minutes

Participants: Curtis, Naomi, Eugene, Beni, John, Simon, Lubomir, Mark, Tim

1. FDC Update
   1. First production cell with new (Viton) O-rings was assembled. All G10 grooves were coated twice with Hysol. Since the O-ring is sticking up only 10 mils (0.25mm) above the frame surface the flatness tolerances must be very tight and practically difficult to achieve. We had a huge leak, "fixed" by using C-clamps. Final result for the oxygen contamination is 900-1000ppm, which is a significant improvement, but twice higher than what we expected from the testing chamber (results from all the measurements are attached above in the agenda).
   2. Two new tests were set up today: one to investigate again the EPDM O-rings and the other is to see the effect of the frame deformation in the production cell, where the end window was replaced with thick Lexan sheet.
   3. Production continues with lower rate: second wire frame for package #4 was strung, techs working also on several cathodes for this package.
2. CDC Update
   1. Construction
      1. The cheeseplate has been polished and is now transparent. It will be installed on the CDC when the holes have been cleaned again. The standoffs are in place waiting for it. The thermocouple gear has arrived, Gary is planning to cover each thermocouple in heatshrink from approx 1/2 inch from the junction to after it exits the plenum. This is to avoid gas travelling inside the kapton. Both ends of the heatshrink will be sealed with glue. Also the holes which the thermocouples pass through will seal better with glue&heatshrink than glue&kapton.
      2. Naomi and Gary have been working on wire map plans. One such plan is linked to the agenda. The wires are divided between the boards by the mapper and then allocated to the pads on the board by a program which estimates the wire length and draws a schematic of the connections (the program takes some wire curvature into account but the maps are easier to read if they use straight lines). The example in the link uses 3-5 layers of straws per board. Another plan with only 3 layers per board (where possible) needs 40 more 5-inch wires but neither plan needs any wires longer than 5". (The boards are numbered ring A-I with A central, and 1 to 26 clockwise within each ring, starting at 9 o'clock.)
      3. Tim has some results from the CDC survey to discuss, will send documents.
   2. Prototype
      1. CDC_prototype_more_on_timing_3 Naomi has more fadc timing study results taking signal drift time as the point where the pedestal meets a straight line through pedestal mean + sigma and pedestal mean + 4sigma, for a series of prototype tilt angles. She also tried fitting the drift time histogram with a combination of exponentials to obtain tzero (as in Avolio ATLAS paper), this is not as easy as it might seem, it produces an estimate of t0 within a few ns of that obtained in the customary fashion - fitting the leading edge with a straight line and then adding additional time to optimize the resolution. A good starting point can be obtained by eye as 2/3 of the way up the leading edge of the histogram. There is a series of small bumps in the drift time histogram, possible causes were discussed.

Software Minutes

Participants: Curtis, Naomi, Beni, Simon, Mark, Paul

1. Kinematic Fitting
   1. Simon is working on improving the tracking errors for use in kinematic fitting. To first-order the pulls and confidence levels look reasonable, but there are still areas for improvement.
2. Spiral Tracks
   1. Paul is still working on reconstructing low-momentum, spiraling pions in the CDC. He has both the track veto-ing and spiral-linking portions of the code integrated, and is working on bug fixes and testing them.