Minutes 8-8-2007
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FDC Weekly Meeting
Date: August 8, 2007
Participants: Daniel, Simon, Brian, Tim, Chuck, Fernando
Next Meeting: August 15, 2007
Contents
Cathode Update
- The +/-15 degrees cathodes for the small-scale prototype have arrived from CCT Marketing. The order consists of 6x2 boards total. These boards have 2 um of copper on a 1 mil Kapton backing. - Simon checked the boards out after the meeting with an Ohm meter and found no short problems! - Brian will mount two of the boards to our remaining G10 frames. - Brian has still not heard from Sierra if they can make the boards for our large-scale prototype.
Prototype Design Planning
- No discussion on the STBs and HVTBs as Kim and Roger were absent today. - We need to get the outline of the two-piece STBs and HVTBs completed and sent out so that we are certain that boards of this size will not be a problem to manufacture. - We all agreed that the list of design questions have been suitably answered for now. The remaining issue is the size of the deadened beam area on the wire planes and whether we need to split the cathodes in the middle. David Lawrence is looking into this presently and work continues. - Fernando has completed the layout and design of the daughter boards. He will send the final specs to Chuck and to Kim. He will send these boards out for manufacture. He presently has 10 ASICs in his possession and the daughter boards will be stuffed and tested when the board are done. Fernando will begin work on the interface board between the small-scale prototype and the daughter board shortly. We would like this to be ready for October so that we can thoroughly check out the performance of the ASICs. Fernando will contact Mitch and Gerard to find out what we should plan on measuring and quantifying. - Fernando sent the LV connector information to Joe who will order the ERNI connectors. The good news is that these connectors are rated for currents up to 3.7 A/pin. - Fernando and Joe have also had recent discussions on the layout of the LV system. - The sample readout cable order is out and the shipment is expected to arrive in about 6 weeks.
TDC Design
- We had a meeting earlier this week on the TDC design. There it was decided to have a single TDC design for both the BCAL and the FDCs. The differences between the modules will be in the front-panel connections and the number of chips installed. The readout will have two 50-pin connections on the front for the FDC version. - We also discussed the issues with the pulser calibration circuitry for the FDC anodes. The purpose of this system is to provide for a fixed time delay measurement and life check of the electronics and cabling. DSC was concerned about the possibility of cross talk on the daughter board circuitry, although Fernando stated that this was expected to be negligible. The pulser system would be nice to have integrated into the TDC design (which Fernando believes amounts to a minimum of manpower effort), but it is not viewed as critical for the chamber calibration.
Wire Frame Studies
- Brian will be constructing a second composite wire frame with the final dimensions needed for the large-scale prototype. He will then do a stress test of this design to compare to the calculations provided by Tim. This frame will have all of the through-holes drilled into it as well as the o-ring groove. The design is made up from a 3.8-mm thick inner layer of high density Rohacell foam and two 0.6-mm thick G10 skins. - The Rohacell has just arrived and Brian has the G10 skins. He will be work this week to make up the composite frame. The frame will then go to the JLab Machine Shop and it will be completed at the end of this month. - Brian has an epoxy in mind for sealing the o-ring groove, and this will be an important part of the test as the groove goes all the way through the G10 and into the Rohacell.
Magnetic Field Tests
- Work continues apace for the upcoming magnetic field test of the small-scale prototype chamber in Hall B. Simon is working on reconnecting the electronics and stringing the signal, HV, LV, and gas lines. The 8 IUCF MWDC chambers that will define our cosmic ray outside of the magnet are now in the Hall and the gas system will be completed by tomorrow. The chambers will then be conditioned and run up to full operating voltage (cathodes and field wires at ground, sense wires at ~3 kV). - The magnet will be energized later this week and the field mapping will begin. We would like a reasonable size grid in the magnet plane to be completed so that we know the strength of the field and its uniformity. We also need to measure the field above and below the magnet to ensure that the PMTs will not be affected nor the operation/calibration of the MWDCs. Simon will talk to Paul Brindza about TOSCA calculations for this magnet. - We should be able to install our detectors in and around the magnet starting early next week. Our goal is to start cosmic ray runs at zero field by the end of next week.
Simulations
- David Lawrence is completed an updated geometry document that includes the latest FDC geometry and materials (including electronics, cables, support structures, cooling system, rails + supports, and composite frames). This document also details the changes to the CDC design. This document will then be circulated for review and then sent to Richard Jones to implement the changes.
Cooling System
- We had a short discussion of the plans for the cooling system for the on-chamber electronics. We still have a way to go to flesh out the design, but we all felt that all issues were solvable.
Work List
- The FDC short-term work list has been posted on the FDC web site (see http://www.jlab.org/Hall-D/detector/fdc/). This is continually being updated and DSC welcomes any feedback or comments from the group.
Minutes prepared by Daniel. Send any comments or corrections along.