FDC Weekly Meeting
Date: November 15, 2006
Participants: Daniel, Brian, Simon, Chuck, Tim, Roger Flood, Kim Shinault
Next Meeting: Wednesday, November 22, 2006 @ 1:30 p.m.
Roger Flood and Kim Shinault, designers from the Accelerator Group joined our meeting today as they will be working on the wire frame circuit boards. We reviewed the FDC system for them to describe its basic purpose and the design constraints. They will begin work to layout the 3 signal boards and 3 HV boards for the wire plane. Brian will be their point of contact. Tim and Chuck will be in communication as well.
- Roger asked about using 4-layer boards (which still can be 1/32 in thick) to allow for better ground plane coverage and definition. - This was viewed as a good idea.
Frame Hole Patterns
We discussed reducing the number of through bolts. The fewer the bolts, the easier servicing becomes. We started out with 48 and are now down to 24. There is no practical way to clamp the chamber from the outside, and the number of through bolts is necessary to compress the o-rings. So, bolts are located every 15 deg.
- We began discussing electronics cooling. Tim will begin to think about this. We have been told that each preamp channel uses 40 mW. The nominal solution is to use water through small copper lines. - This cooling line could be integrated into the preamp daughter board.
- We have been told that each daughter board will include 3 ASICS (i.e. 24 channels) for the cathode planes. For the anode readout, we must have 2 preamps per daughter board for compatibility with the F1 TDC (unless a junction box is constructed). This still works nicely with our number of channels. - We need to be in contact with the Alberta group to specify the tolerances, thickness, connectors, cooling requirements, pulser line, etc. - DSC will talk with Elton about this.
- The full-scale flex boards can be made by the company if we can find a kapton vendor. The kapton vendor cannot deliver the size kapton we need with 1/7 oz of copper. - We decided to split the cathode plane into 3 separate pieces to get around this. >Tensioning option: Overlap kapton and epoxy -- then tension. >Rohacell option: Use butt joint and roll kapton flat. - The kapton is currently specified as 50 microns thick. Can we go thinner to reduce the material budget?
Cathode Flatness Measurements
- ATLAS had an automated system to measure the flatness of their cathodes and we would like information on their approach and system. - Simon contacted Paul O'Connor at BNL and he provided some names. Simon contacted them and has not yet gotten a reply. - Brian will follow up on this using his contacts at BNL.
- Brian has contact with a plastic manufacturer in Norfolk who he will get to make a case for the cathode planes. Kapton is hydroscopic and while the completed planes sit around, we want them encased with dry air flowing over them.
Minutes prepared by Daniel. Send any comments or corrections along.