Dear collegue,

at the recent Vancouver meeting, some discussions took place concerning the layout of the interaction
regions and also the layout of the experimental hall.

It appears that the decision has been taken to move to 2 14mrad interaction regions,
away from the current baseline of 2 and 20 mrad. This is mostly driven by
cost considerations, if I am correctly informed.

We should look at this issue and see whether there is any overwhelming reason from
physics to push for a small angle interaction region. If there is no input
from us this will be the new baseline, I think.

In addition I got informed that the civil construction people are looking into options
for the detector halls which are similar to the CMS approach: assemble the detector
as much as possible on the surface, and then bring large chuncks of it into a smaller
hall and do only the final assembly undergroud. I would be interested to hear from
people about this - what are your opinions, what are your experiences (if you are member
of CMS, say) what are possible pro's and con's of such an approach. The GDE has asked
us to respond within 4 weeks - which seems awfully soon -

so please enter your opinions here by posting answers or send mail to Ties.Behnke@desy.de

Many thanks, Ties