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[Ext-GDE-67] GDE BCD Change Request from BDS (Surface Assembly of Detectors)



Dear Jim, Francois, Hitoshi,

Nobu Toge from CCB/ILC-GDE here.

I am writing to ask your comments and remarks as Co-chairpersons of
WWS, concerning the BDS change configuration request that was submitted
on Sep. 21, 2006. The description for this CCR can be found at

   http://lcdev.kek.jp/ML/PubCCB/msg00079.html

or as item #17 at

   http://www.linearcollider.org/wiki/doku.php?id=bcd:bcd_history .

This change request relates to an attempt at clarifying the assembly
procedure for ILC detectors.

While the present BDS BCD does not explicitly specify the method of 
underground assembly, it has been implicitly assumed in the BCD that 
detectors are assembled underground. Now, the change request is to 
specify in BCD that assembly of detector will be done on-surface, in 
a manner similar to what was done for CMS detector at CERN. According to 
the requesters, this is expected  to reduce the construction
time of the IR-related portion of ILC, since the detector subassembly work
does not have to wait for completion of the underground hall, and is
also expected to reduce the construction cost.

The information of primary interest from you is your comments, reactions
and assessment on anticipated impacts concerning the detector concept,
its construction, operation and maintenance in conjunction with physics
research potential that this configuration change might incur. We are
interested in hearing both your expert insights as well as opinions
(average, distributions, etc) of the WWS members and their friends that you
have access to.

We note that the MDI has had opportunities to discuss on this matter
in the past month (August 15, 2006) with its  minutes having been sent to
WWS, which is available as

http://www-project.slac.stanford.edu/ilc/acceldev/beamdelivery/rdr/docs/CCR_surface/Revised%20MDI%2\
0meeting%20minutes%20(81506).txt .

Therefore, I believe this particular topic is not too new to you.
However, we feel that it is prudent to ask for opinions of the
bigger WWS body, and to incorporate them as inputs to evaluate this
change request for CCB. And if the minutes above already represents 
the consensus opinion of WWS, with a good approximation, CCB should
learn it explicitly from you, too.

We would greatly appreciate if you could respond as soon as
possible.

Sincerely,

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