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Change Request Action - Central Damping Rings
- Subject: Change Request Action - Central Damping Rings
- From: "Barry C. Barish" <barish@xxxxxxxxxxxxxxxx>
- Date: Sat, 04 Nov 2006 15:15:07 -0800
I would like to announce that the GDE Executive Committee has
officially approved the Change Request (CCR#18) for Parameter /
Layout section of the GDE ILC Baseline Configuration Document as
recommended by our Change Control Board. This was a Class-2 change
that requires EC approval. This change redefines the ILC layout such
that the electron and positron damping rings will be contained in a
single, common tunnel which is situated centrally around the
interaction regions. The new layout will now officially become our baseline.
The main motivation for this change is the substantial cost reduction
by eliminating the entire civil construction costs for one 6 km
damping ring tunnel and consolidating the conventional facilities for
the damping rings. There are some compensating new costs in beam
transport, those are small compared to the civil construction savings.
Many details resulting from this change are still to be worked out,
but it was the judgement of the CCB and the EC that those will not
change the conclusions to make this change and therefore we feel we
can make this change and defer some of the detailed optimization
until after the RDR is complete. Nevertheless, it is important to
bring the BCD document up to date as soon as possible.
I would especially like to thank Ewan Paterson for so effectively
completing this study and bringing a well-worked CCR to our CCB and I
also note and appreciate the concerted and rapid work of the CCB in
bringing this action to completion.