(B. Schumm - U.C. Santa Cruz)

Participants:
    J. Brau    Oregon
    R, Dubois  SLAC
    T. Johnson SLAC
    M. Iwasaki Oregon
    K. Riles   Michigan
    M. Ronan   LBNL
    B. Schumm  Santa Cruz

After some discussion, it was decided that there was no longer any
compelling reason to have different vertex detectors for the L and S
detectors. So, the Damerell design will be adopted for both. Details
of this design will be distributed by Jim. The associated beampipe will
be 1.0 cm for both `L' and `S', with 1/2 mm thick Be (I get 0.28% X_0).
The layers will be 0.12% X_0 thick. The cryostat parameters adopted are
from Jim, although Richard's notes on them are somwhat vague, especially
for the forward sections. Bruce will try to square these with Richard/Jim.

We discussed the specifics of the small detector. The doublet layer radii are
14, 15, 42,43, 70 and 71 cm. The Z extent is whatever it takes to provide
cos(0) = 0.9 ceverage, rounded UP to the nearest integer cm.
The disks are at Z positions of 31, 61, 91, 121, and 149 cm. The inner
radial extent is given by the mask (outer edde at 110 mrad) + 1cm clearence.
The outer radius is constrained by the barrel layers. Keith and Bruce still
need to agree on exact numbers for all of this.

We discussed the inclusion of forward disks in the L option (which now
has an identical beampipe, vertex detector, and cryostat as the S option).
Resolution comparisons of 50cm and 25cm inner radius TPC systems done by Keith
and Bruce showed preference for the 50cm system over most of the p, theta space,
so this= inner radius was chosen. It was decided that this inner radius (larger than
in the previous L design) will be acheived while maintaining 144 layers.

Finally, it was decided that there should be a single intermediate tracking layer
at a radius of 48cm. This layer will extend in Z to the first disk layer. It will
be azimuthal SI strips with 7um resolution and 1.0%X_0 thickness.
This decision was based on a study which shows improvement in the
momentum resolution at low cos(theta) for momenta greater than 30 GeV/c.
This improvement grows to about a factor of 2 for momenta greater than
100 GeV/c.