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[Ext-GDE-74] CCB Response to Layout (centralized DR) Config Request of Oct.7, 2006 (CCR#18)

Dear Colleagues,

I am announcing that the CCB response, with regards to the ILC Config 
Change Request for the Parameter/Layout section of Oct.7, 2006 (CCR#18), 
is now posted at -


The change request was submitted by J.M.Paterson on Oct.7, 2006.
It seeks to revise the baseline layout of ILC so that electron
and positron rings are to be built in a single, common tunnel
(6.7km circumference) centrally around the interaction point.
The main motivation behind this proposal is to reduce the extra
cost that would have been required for two nearly identical DR
tunnels in the previous baseline.

The requester suggested Class 2 for this request, to which
CCB concurred after evaluation of the cost impacts. CCB gratefully 
acknowledges the assessment reports offered by colleagues from 
the GDE Cost Engineering team at the CCB hearing on CCR#18. 
The minutes of this hearing is available at


The summary CCB response is as follows -

1.  CCB agrees that the cost change (in this case, reduction) expected 
    from this change request is substantial, such that it qualifies as 
    Class-2. Consequently, CCB assumes that its role concerning this change 
    request is to assess its merits and to make a recommendation to EC, 
    rather than to make a final configuration change decision.

2.  CCB recommends EC to adopt this change request, with small refinements 
    on illustrations and the text, for reasons detailed in the "Discussion"
    section of the full report (ccb-com-layout20061028.pdf. This file
    also includes the revised replacement text for BCD).

3.  CCB will encourage the relevant parties, and will work with them, to 
    update the "RTML" and "Damping Ring" sections of BCD in accordance 
    with the updated layout. (CCB acknowledges that as of Oct.25, 2006,
    a relevant RTML change request has been submitted - CCR#19)

4.  CCB wishes to take this opportunity to urge the parties responsible 
    for the "e+ source" and "Conventional Facility" sections to update 
    their BCD descriptions which are long over due.

Additional communication and reference materials are available for
viewing, under CCR #18, at


When GDE EC makes the final decision and approves this change request,
CCB will accordingly update the Parameter/Layout section under


On the basis of the "Approval Recommended" status of CCR#18, CCB is
now initiating its formal review process for CCR#19 (RTML change request
that has been triggered by CCR#18).

With best regards,

- Nobu Toge (KEK, Accelerator Lab)
  email: toge@xxxxxxxxxxxx
  voice: +81-29-864-5224
  fax:   +81-29-864-3182