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

Dear Nobu,

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.


N.Toge wrote:
Dear Colleagues,

I am announcing that CCB has received a change request for the BDS
section of ILC Baseline Config Doc from A.Seryi who is representing
the BDS AG.

This change request relates to a likely scenario for the gamma-gamma
upgrade of the BDS and IR to thoroughly examine in the timescale beyond 

The requesters suggest Class 1 as classification for this change
request. The CCB chair concurs, so it will be treated as Class 1.

I have asked G.Blair and T.Markiewicz to act as CCB reviewers (to be
confirmed shortly).

Now this request is brought to review by CCB, and is also open to
general discussion. Any members of GDE or GDE-related task groups with
comments or questions on this request, please, direct them to
ml-ccb@xxxxxxxxxxxx and/or ml-ext-gde@xxxxxxxxxxxx by the end of
Friday, May 19, PDT.

BCD is available at
BCD change history is available at
BDS-related RDR materials are compiled and posted at


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

[CCB-381] change request in BDS: gamma-gamma upgrade
"Seryi, Andrei" <seryi@xxxxxxxxxxxxxxxxx>
Tue, 16 May 2006 21:18:10 -0700
"Angal-Kalinin, D \(Deepa\)" <d.angal-kalinin@xxxxxxxx>, "?? ?" <yhitoshi@xxxxxxxxxxxxxxxx>, "Seryi, Andrei" <seryi@xxxxxxxxxxxxxxxxx>

1) Requester¡Çs contact information.
	On behalf of BDS area leaders, 
	Andrei Seryi, seryi@xxxxxxxxxxxxxxxxx

2) Concise summary of the Change Request.
 The modified text include description of a likely 
scenario for gamma-gamma upgrade. Requirements for gg IR 
design and beam dump for gg are briefly discussed and 
references are given where more information can be found. 
It is discussed that either 20mrad IR or 14mrad IR may be 
upgraded to 25mrad for gg by introduction of a bend between 
FF and E-collimator. 
It is discussed that due to the assumed need for downstream 
diagnostics in e+e- and the need for reversibility of gg upgrade, 
it is beneficial that crossing angles for e+e- and gg options
are not the same, and sufficiently different to allow 
independent and sufficiently shielded beam dumps. 
It is suggested that more study should be done after RDR, 
namely during TDR time frame. The list of R&D items is given. 

3) Replacement text for the relevant part of BC descriptions.
 The Word file with track changes ON, is attached

4) Classification in requester¡Çs view.
 This is probably Class 1. 
 From one point of view, this added text can be considered 
as insertion of a missing section (class 0), but the implications 
may be not minor. However, one need to note that there should not be 
implications for RDR work and cost, but only for TDR time frame. 

5) Reasonably detailed descriptions and reasons for the Change Request.
 The gamma-gamma upgrade scenario was not described in BCD
but need to be discussed, as gamma-gamma option may be important 
for physics.

6) Assessment of the impacts of the change in requesters¡Ç view.
 The change will allow to include in BCD the description of one of 
the most likely (as understood by us at present) gg upgraded scenarios 
and focus on studies of the technical feasibility in TDR time. 

L. Warren Funk
Accelerator Division
Jefferson Lab
12000 Jefferson Ave.
Bldg. 12, Rm. C-221, MS-12A2
Newport News, VA 23606
Phone:  757-269-7690
Fax:  757-269-6099
email:  lwfunk@xxxxxxxx