W&M report 03-18-2004


Meeting with Nilanga (UVA) at JLab  (Mike Finn, David Armstrong, Klaus Grimm)
  Nilanga was involved in building the Hall A VDCs and is bulding 3 HDCs for BigBite at present at UVA.
  He is using proven and pratical techniques for building DCs, which will save us a lot of time for the construction.
  Will visit his lab in 2 weeksfor hands-on experience

    wire alignment
         DC wire plane is placed/fixed on a outer alignment frame. This frame has the shape of a ladder with two square bars with precision holes
         to string and hold the wires in a defined position. The frame is modular  and quite easy to build

    wire tension
         wire spool is mounted on a motor. The wire tension is given by the controlled "winding up power" of the motor.

    wire position survey
         A stepper motor controlled arm with an attached CCD camera scans the wire position along the wire plane

Meeting with Bill Vulcan (Hall C), Bogdan Wojtsekhowski (Hall A)     (Mike Finn, Klaus Grimm)
   Bogdan: checking possibility to transport spare Hall A VDC to W&M as a test chamber.
   Conclusion: Carrier and/or VDC is too big for the W&M lift ... Testing should be done at JLab

   Bill:  Promised to lend us the a spare gas handling system (rack).
           Discussion about the usage of aluminium wires compared to W or Cu-Be wires in respect of multiple scattering.
           ( HMS: 150um gold plated aluminium wire , DC3: ~25um gold plated tungsten wire)
           Conclusion: by rule of thumb the volume ratio is  (150um / 25um)^2 = 36  , use robust tungsten wire even it has a shorter X0.
                              (HMS had to use Al since it will be sometimes used for ~200MeV electron detection)
                              therefore we use robust tungsten wire  instead of delicate aluminium wire

W&M Detector Lab status

  - New Orleans: active DC3 area is  210cm x 25cm , means 25 cm shorter !!!
  - Structural evaluation of flooring in Detector Lab: floor cannot carry a ~10k granite table, floor load is exceeded by factor >2 ..
  - Bill Cooke is willing to lend us a laser table: surface 4'x10', thickness 1'. Laser table is on the same floor as the detector lab !!!
      Some ideas on how to get the table in our detector lab (special trolley: allows to tilt and rotate the laser table,  table ends will be at different heights)
      In addition: we have to tilt the DC planes to get them into the lift
- ceiling tiles will be replaced (dust), new AC            

DC3 design studies/ technical drawings

Mike has a lot of ideas on how to simplify the building and alignment of the DCs.
At present only scratch paper and napkin drawings.
Starting to learn on how to used SolidWorks to produce technical drawings and sketches.
 Sideview of DC3 (pic1) and 3D view (pic2) .