Re: [Ext-GDE-46] ML Change Request - June 12, 2006

[Warren Funk <lwfunk@xxxxxxxx>]

Dear Nobu:

I agree to act as reviewer for this change.

I disagree with the classification of this change as Class 0.  The proposal calls for an increase of ~170 magnet sets.  I estimate that the cost of this will fall somewhere between $15M and $20M, when development costs are included.  There is evidently some offset (savings in RF distribution) but unless I'm missing something (it's happend before!) that won't be large.

I request that you consider classifying it as Class 1.

Regards,

Warren

N.Toge wrote:

Dear Colleagues,

I am announcing that CCB has received a change request for the Main
Linac (ML) section of ILC Baseline Config Doc from C.Adolphsen,
who is representing the ML AG.

This change request mainly relates to layout specifications for
the cryostats, beam position monitors, focusing quads
and the associated orbit correction dipole magnets. Another
part of the change request relates to elimination of a duplicate
subsection (cryogenics).

The requesters suggest Class 0 as classification for this change
request. The CCB chair tentatively agrees to treat this as Class 0,
pending consultation within CCB.

I am asking W.Funk and C.Pagani 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, June 16, PDT.

BCD is available at
   http://www.linearcollider.org/wiki/doku.php?id=bcd:bcd_home
BCD change history is available at
   http://www.linearcollider.org/wiki/doku.php?id=bcd:bcd_history
ML-related RDR materials are compiled and posted at
   http://www.linearcollider.org/wiki/doku.php?id=rdr:rdr_as:main_linac_home

Sincerely,

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

  

---

Subject:

[CCB-445] Linac Change Requests

From:

"Adolphsen, Chris" <star@xxxxxxxxxxxxxxxxx>

Date:

Sun, 11 Jun 2006 23:19:03 -0700

To:

<ml-ccb@xxxxxxxxxxxx>

To:

<ml-ccb@xxxxxxxxxxxx>

CC:

"Solyak, Nikolay" <solyak@xxxxxxxx>, <lutz.lilje@xxxxxxx>, "Hitoshi Hayano" <hitoshi.hayano@xxxxxx>, "Tom Peterson" <tommy@xxxxxxxx>, "John Tompkins" <jct@xxxxxxxx>

The Main Linac section of the BCD is attached and includes changes and refinements on page 36 and page 38 (using Track Changes) for which we request approval by the Change Control Board - we believe these to be type zero. 

On page 36: 

Have one quad every three cryomodules (i.e., one per rf unit). This was the Snowmass recommendation and was stated in the BCD until Nick/Tor changed it to one in four cryomodules without consulting the Linac Group. This configuration greatly simplifies the rf distribution layout, and is more amenable to future upgrades of the machine to higher energy (the quads in this case may not have to be replaced).

Use longitudinally separated quad and corrector magnets as opposed to combined-function magnets. This choice will eliminate the dipole fields that would otherwise be induced in the quad windings from persistent currents excited by changes in the corrector settings. Also, the quads in the upstream end of the machine may be superferric as suggested by the Magnet group.

The BPM spec was not changed, but it may be in the future - the LET group has still not decided what BPM resolution we need.

Within the linacs, measure beam energy and energy spread only in the electron undulator section and its counterpart in the positron linac (both are part of the Positron Injection system). The BCD recommends measuring it at two locations in the linac, but this does not seem cost effective (the beam energy and energy spread would still be measured at the end of the RTML and the beginning of the BDS). As for beam size measurements elsewhere within the linac, the only space readily available are the warm sections between the cryogenic units (it is difficult to install laser wires in a cryogenic environment). With the limited number of wires, local emittance measurements will require semi-invasive quad scans.

The remaining changes on this page are updates of out-dated information

On page 38: 

Nobu included the cryogenic section twice, so I deleted the second version.
  

-- 
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