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[CCB-385] Re: [Ext-GDE-41] BDS Change Request - May 17, 2006



Dear Warren,

> I believe that we are seeing here one of the unfortunate consequences of
> incorporating ACDs and upgrade scenarios into the BCD and subjecting
> them to the same level of change control. I have yet to read the
> material itself, but nowhere in Andrei's cover letter is there any
> suggestion that the maintenance of the option of a future upgrade to
> gamma-gamma has any impact on the baseline design. I therefore propose,
> unless there are cost/schedule/technical performance issues for the
> baseline in what Andrei proposes, that the correct classification of
> this request is Class 0.

Thank you for pointing out this issue.

My reasoning for calling this BDS change request as "Class-1" 
is as follows -

- To consider this gamma-gamma option as a future upgrade to
  seamlessly integrate already *might* have some cost or
  technical implications to the present BDS BC, which had
  better be thought through, and
- If/when promoted as BC in the future, this configuration
  change (gamma-gamma upgrade) is definitely going to call
  for some additional (probably big) budget.

As I understand it, and as you correctly note, Andrei's change 
request pertains to a gamma-gamma upgrade scenario for GDE to 
examine in the time-scale *beyond* RDR.

In that sense, this is more like an AC request rather than a BC
request. However, its cost and technical implication is most likely 
significantly more than zero, and plus.

The present CCB classification structure is not "fine-grained"
enough to specifically deal with this type of cases. This is
the first of such instances that CCB is facing, and I presume
there are more similar change requests to come in the future.

Ideally we had better solicit inputs from AGs/GGs/TGs for their
ideas on potential change requests of similar category, and CCB
should develop a suitable addendum to our change configuration 
procedure. However, I do not think now is the best time to do so 
given the general pressure to sail ahead towards RDR. 

Therefore, I consider that we have to take an "learn-as-we-fly" 
approach on this one in this meanwhile. 

And CCB should examine to see if this BDS change request from 
Andrei and the colleagues is "not totally out of technical 
question" from the standpoint of present BC, at least briefly,
if not thoroughly. In that sense, I consider inadequate to call 
it Class-0 (zero technical implications to assume).

Sincerely,

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