Request to Modify MVD Radial Boundary

J. Boissevain, B. Jacak, J. Kapustinsky

November, 1995

We propose to increase MVD radial boundary from 20 cm to 26 cm.

Previous situation:

  1. The hinge assembly extended beyond the radial boundary at the endplates by approximately 2cm. We didn't worry about this as the cooling hoses exited the MVD radial boundary near this point, 3 cm in Z in from the endplate. The hinge should, however, be within the MVD radial boundary.

  2. A 30 contact connector to provide DC power and control signals to the MCMs (this is the "Power and Communication Cable") was used; this number of contacts is no longer adequate.

  3. The MCM size was 3 cm high and now needs to be increased.

Proposed Situation

  1. The MCM size has increased to 3.5 cm (best guess). It is still not clear if this number has stabilized due to ongoing heap manager deveopment, so we must reserve some contingency in the radial boundary.

  2. The hinge assembly is now inside the radial boundary.

  3. The cooling pipes now exit the end plates allowing flexibility in where they exit the radial boundary.

  4. An additional 20 contact connector has been added to the power and communication cable. We currently believe that 50 contacts will give adequate contingency of contacts for a still changing readout design.

  5. The proposed radial boundary is 25 cm with a 1 cm contingency
Figure 1 shows an end-on view of the MVD which fits into the proposed radial boundary of 25 cm. The requested 1 cm contingency is not indicated on the figure. The thickness of the enclosure is 6.35 mm (1/4 inch). The end motherboard (which supports the pad detectors and interfaces to the external DCM and trigger interface boards) is currently being designed; the size shown reflects reasonable space for routing circuit board traces from the 50 contacts. A candidate connector has been identified, and is the finest pitch connector commercially available. The duct shown next to the connectors matches the cross sectional area of the air cooling plenum (to minimize the turbulence when the air flow is split between strip and pad detector plena). The central MCM plenum is matched to the location of the pad detector MCM plenum. It cannot be moved closer to the collision point in R without increasing the background seen by the electron arms. The hinge size is the current best estimate allowing sufficient bolt space.

Figure 2 shows 3-d view of the MVD with the proposed geometry. The cooling plenum and adapter for the pad detector MCM's is shown.

Last Updated: 1/3/95