1 Dec 2000 Meeting at Harvard

Notes by E. Hazen hazen@bu.edu.

1. Ground plate will be rounded to follow tube outline on upper side of step. This will reduce the possibility of discharge from the hedgehog boards on the 8.5 degree chambers, where the board is adjacent to the ground plate.

   
   Figure 1: Ground Plate Modifications
   (click to enlarge)

2. An observation: for the "standard" hedghog board outline, 2mm of clearance exists most places between the hedgehog and the tubes and faraday cage. There are two exceptions (see figure) where a tab is bent down from the baseplate to close a gap in the shielding. At this location the clearance is essentially zero with the current hedgehog outline. The hedgehog should be made 2-3mm smaller at these locations. This creates a problem for the jumpers (see below).

   
   Figure 2: HV Faraday Cage
   (click to enlarge)

3. The height and length of the faraday cage on the HV end can be increased as requested by Agostino. This should leave plenty of room for whatever HV jumper design is finally used.

4. There is too little clearance between the jumper sockets and the side of the tubes at the "step". This is because the HV capacitor is between the tube socket and the jumper (see figure).

   This could perhaps be remedied by changing the entire layout to a mirror image such that the HV capacitor is on the other side of the tube away from the step.

   Or, flexi-circuit jumpers be pursued as an alternative. The sockets for the flexi-ciruit to connect could be moved to a location well away from the end of the PC board near the faraday cage.

   
   Figure 3: Jumper Clearance
   (click to enlarge)