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Revision r9 - 05 Mar 2008 - 22:52:39 - MarkPalmer
Parents: WebHome
EDR Lattice Evaluation Page
Table of Contents:
- GDE Sendai Meeting Lattice Evaluation
- Lattice Evaluation and Comparison Information
- OCS8 Lattice (Developed from RDR baseline)
- FODO4/5 Lattices (Variable momentum compaction factor, two dipoles per arc cell)
- DCO Lattice (Variable momentum compaction factor, one dipole per arc cell)
- Lattice Evaluation Submissions
GDE Sendai Meeting Lattice Evaluation
- GDE Sendai Meeting Lattice Evaluation: DRLatticeEvaluation_2008_0306.pdf (Version of March 6, 2008)
Responses to Lattice Evaluation
Response from Jie Gao
Dear All, After reading the evaluation tables, I recommend FODO5 to be the baseine since FODO5 get the highest point in the performance among the four choices " Lattice design and dynamical properties" which is the most important for ILC damping design at this stage after cost saving compared with OCS8, and I hope our colleagueus make a good choice for ILC DR which has the best performance, and focused on the EDR design. Best regards Jie GAO
Response from Susanna Guiducci
Hi Mark, Andy and Junji I mainly agree with ranking reported in the lattice evaluation document; below just a few comments: *1) * Lattice design and dynamical problems I think that the optimal value of the momentum compaction for RF and bunch length is around 2 e-4 and therefore the choice is between *FODO5* and *DCO*, which are centered on this value. *FODO4* has a satisfactory dynamic aperture at ac=2e-4. This is the result of an accurate optimization work and shows that FODO lattice has a large flexibility ( 4-fold and 8-fold symmetry, ac=6 e-4 - 1.7 e-4) and it can achieve a satisfactory dynamic aperture. *DCO* has a dynamic aperture satisfying the minimum design requirements for ac=2.8e-4 and 1.7e-4. I'm confident that it can be improved with dedicated work. *2) *Conventional facilities and services For the EDR phase the choice of the layout is crucial since it is strictly connected to the choices of the CFS. The racetrak layout of the *DCO *lattice with 2 long straights, where the major components are clustered in alcoves within a few hundred meters from the access shafts, seems to me the optimal solution for costs reduction and operational efficiency. Therefore I agree with the choice of the *DCO* lattice for the EDR. I think that the choice of the arc cell is less critical than the layout choice; more or less all the lattices can achieve the design parameters but it is important to fix one and to concentrate all the efforts on dynamic aperture optimization, evaluation of low emittance tuning and collective effects and on cost/benefits optimization. Thank you for the exhaustive work done for the comparison, Susanna
Response from Craig Burkhart
Mark, Unfortunately, I had to leave yesterday's discussion just as you started into the evaluation table. My interpretation of the Table and the comments that have been subsequently exchanged is that all four approaches are technically sound, the DCO is marginally superior to either FODO and the OSC8 is marginally inferior. That said, cost should then become a primary concern. There are clearly cost components in the evaluation, but since the technically merits of the competing systems are similar shouldn't a greater weighting be placed on cost? If you conclude that the present evaluation places sufficient weight on cost, I certainly support your conclusions. Craig
Response from Mike Zisman
Folks: I do think there is merit in Craig's comments. In practice, I think it means that you should try to keep the FODO5 lattice "alive" until there is an opportunity to do a cost comparison. Insofar as we suspect that the DCO lattice will be less expensive, there should be no objection to using it as the baseline, with the FODO5 lattice serving as backup. From an engineering perspective, that probably means doing a bottom-up cost estimate for the DCO version with subsequent "deltas" to assess the relative costs of FODO5. This could even be a management milestone at some point, say one year from now. ...something to consider. Cheers, Mike
Response from Louis Emery
To all, I agree with the relative scores in the tables. I would weight the first table more. But I think it would not change the order of the results. I'm leaning towards the DCO cell structure because of the reduced number of magnets, and I think the DA problem is not insurmountable. I missed the webex session on Tuesday, so I have some comments and questions: I'm not sure how the DCO lattice at 100 degrees/cell ended up with a (much?) smaller dynamic aperture than the FODO5 lattice with 108 degree per cell. I see that the cell length for DCO is shorter (making the dispersion smaller) than the FODO5 FODO cell, perhaps to partially compensate the larger I5 created by the shorter and stronger dipole. I think the dynamic acceptance of FODO cells with constant circumference should scale roughly as the cell length squared. So a shorter dipole magnet resulted in a smaller dynamic aperture. Andy, was using a 2x field in the dipole for reducing the total dipole magnet cost? Could the magnet be longer without disrupting the mechanical layout much? To rephrase a point by Aimin, if maintaining a 90 degree phase advance is important for dynamic aperture, then an "upgrade" of momentum compaction from 1.7e-4 to a value 25% lower can be done with the conversion of the DCO cell to a TME-cell (keeping 90 degree cell) by the insertion of one quad. This is, of course, at a cost of 192 magnets. How does the lower symmetry of the DCO lattice affect the dynamic aperture? Could we have the superconducting stuff together in two groups at a 90 degree azimuth relative to the injection and extraction (like FODO4 but with doglegs added to reduce heat load)? Thanks. Louis Emery
Response from Andy Wolski
Dear Louis, Thanks for your comments. You raise some good questions: the dynamic aperture in particular is something that we should look at carefully, to make sure that we understand the issues, and arrive at an optimum solution. Regarding the dipole field, this (or, equivalently, the dipole length) was used as a variable in the cell design of the DCO lattice to control the momentum compaction factor. But the dependencies are not strong, and there is plenty of space in the lattice if it is found that a longer magnet would be preferable. I'm not sure that cost is a real issue. My guess is that to first order, the dipole cost depends on the beam energy and total bend angle. Since all the lattices we considered for the baseline have a total bend of 2pi and all operate at 5 GeV, I would expect any differences in dipole cost to be small. The installation costs may depend more on the number of dipoles (so, a smaller number of dipoles may be cheaper to install, even if each individual dipole is heavier), but I'm not sure about this. I thought the comparison between the OCS-style and DCO-style arc cells presented by Aimin was extremely interesting. I had not viewed a TME cell in that way before. It does raise some interesting upgrade possibilities, as you point out. The layout is also an issue that we need to pursue. While it is necessary at this stage to have a single lattice identified as the baseline, it is very important to maintain at least one alternate, so that we can understand the influence of things like the layout on cost, dynamics, etc. Best regards, Andy.
Response from Mark Palmer
Hi All, I would like to say thank you to everyone who sent a response to the lattice evaluation exercise. An updated version of the lattice evaluation document has just been placed on the lattice evaluation page (%SCRIPTURLPATH%/view/ILC/DampingRings/LatEvalPage) along with copies of the responses. The direct document link is: %PUBURLPATH%/ILC/DampingRings/LatEvalPage/DRLatticeEvaluation_2008_0306.pdf At this point, both of the lattices which can accommodate 6 mm bunch lengths (FODO5 and DCO) appear promising. The growing consensus is that both should be maintained while further investigations of the beam dynamics, technical issues, and costing are explored further. The cost, reliability and availability issues that appeared both directly and indirectly in the evaluations favor DCO because of the clustering of many technically challenging components in the rings as close as possible to the two access shafts. It is also the case that most feel that any dynamics issues remaining in the designs can likely be successfully dealt with. Thus the recommendation that has been passed to the project managers is that the DCO be specified as the baseline lattice and FODO5 as the alternative lattice for the ILC Technical Design Phase. If there are further comments/concerns, please continue to send them to the full mailing list. Cheers, Mark
Lattice Evaluation and Comparison Information
- Specifications for EDR lattice: EDRLatticeSpecifications.pdf
- Comparison of parameters for lattice options (OCS8, FODO, DCO): LatticeOptionsParameters.pdf
OCS8 Lattice (Developed from RDR baseline)
Lattice Documentation
- ILCDR07-KEK (Dec 07) presentation of the OCS8 lattice: Emery.pdf
- ALCPG07 (Oct 07) presentation describing status of the OCS8 lattice: OCS8_DR_Lattice_Xiao.pdf
MAD Deck
- OCS8 lattice file (xsif format): ocs8.xsif
- OCS8 MAD job file: OCS8.Run.mad8
Comments and Results
- See below for instructions on submitting comments
- Comments Received:
- None
FODO4/5 Lattices (Variable momentum compaction factor, two dipoles per arc cell)
Lattice Documentation
- Introduction to FODO4 lattice: Introduction_to_FODO4.pdf
- ILCDR07-KEK (Dec 07) presentation on the FODO lattice: ILC_DR_FODO_lattice-sunyp.pdf
- ALCPG07 (Oct 07) presentation describing the alternate FODO lattice: FODO_DR_Lattice_Gao.pdf
MAD Deck: FODO4
- FODO4 lattice file: FODO4.xsif
MAD Deck: FODO5
- FODO5 lattice file: ILC_DR_FODO5.mad8
Comments and Results
- See below for instructions on submitting comments
- Comments Received:
- None
DCO Lattice (Variable momentum compaction factor, one dipole per arc cell)
Lattice Documentation
- DCO lattice description: Wolski.pdf
MAD Deck: DCO
- DCO lattice file: DCO.xsif
- Magnet settings for 72 degree phase advance arc cell DCO (alpha = 2.8x10-4): kvals.72deg.xsif
- Magnet settings for 90 degree phase advance arc cell DCO (alpha = 1.7x10-4): kvals.90deg.xsif
- Magnet settings for 100 degree phase advance arc cell DCO (alpha = 1.3x10-4): kvals.108deg.xsif
- MAD job file for DCO lattice: DCO.mad8
Comments and Results
- See below for instructions on submitting comments
- Comments Received:
- None
Lattice Evaluation Submissions
- Please submit comments and lattice evaluation studies by email.
I | Attachment | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|
mad8 | DCO.mad8 | manage | 19 K | 08 Feb 2008 - 12:30 | UnknownUser | MAD job file for DCO lattice |
xsif | DCO.xsif | manage | 16 K | 08 Feb 2008 - 12:28 | UnknownUser | Lattice file for DCO lattice |
DRLatticeEvaluation_2008_0306.pdf | manage | 33 K | 05 Mar 2008 - 22:48 | MarkPalmer | GDE Sendai Meeting Lattice Evaluation | |
EDRLatticeSpecifications.pdf | manage | 114 K | 08 Feb 2008 - 12:41 | UnknownUser | Specifications for EDR lattice | |
Emery.pdf | manage | 553 K | 08 Feb 2008 - 12:36 | UnknownUser | OCS8 lattice presentation at ILCDR07-KEK | |
xsif | FODO4.xsif | manage | 14 K | 11 Feb 2008 - 09:23 | UnknownUser | FODO Lattice File |
FODO_DR_Lattice_Gao.pdf | manage | 689 K | 11 Feb 2008 - 09:25 | UnknownUser | Alternate FODO Lattice Presentation at ALCPG07 | |
mad8 | ILC_DR_FODO5.mad8 | manage | 14 K | 08 Feb 2008 - 12:49 | UnknownUser | Lattice and MAD job file for FODO5 |
ILC_DR_FODO_lattice-sunyp.pdf | manage | 689 K | 11 Feb 2008 - 09:27 | UnknownUser | FODO lattice presentation at ILCDR07-KEK (update) | |
Introduction_to_FODO4.pdf | manage | 42 K | 11 Feb 2008 - 09:29 | UnknownUser | Introduction to FODO4 lattice | |
LatticeOptionsParameters.pdf | manage | 102 K | 08 Feb 2008 - 12:42 | UnknownUser | Comparison of parameters for lattice options | |
mad8 | OCS8.Run.mad8 | manage | 3 K | 08 Feb 2008 - 12:27 | UnknownUser | MAD job file for OCS8 lattice |
OCS8_DR_Lattice_Xiao.pdf | manage | 828 K | 07 Nov 2007 - 18:46 | MarkPalmer | OCS8 Presentation at ALCPG07 | |
eml | Response_1_Gao.eml | manage | 17 K | 05 Mar 2008 - 21:51 | MarkPalmer | Response from Jie Gao |
eml | Response_2_Guiducci.eml | manage | 9 K | 05 Mar 2008 - 21:52 | MarkPalmer | Response from Susanna Guiducci |
eml | Response_3_Burkhart.eml | manage | 18 K | 05 Mar 2008 - 21:53 | MarkPalmer | Response form Craig Burkhart |
eml | Response_4_Zisman.eml | manage | 20 K | 05 Mar 2008 - 21:53 | MarkPalmer | Response from Mike Zisman |
eml | Response_5_Emery.eml | manage | 4 K | 05 Mar 2008 - 21:54 | MarkPalmer | Response from Louis Emery |
eml | Response_6_Wolski.eml | manage | 5 K | 05 Mar 2008 - 21:54 | MarkPalmer | Response from Andy Wolski |
mad | RunDR.mad | manage | 2 K | 07 Nov 2007 - 11:29 | MarkPalmer | MAD job file for FODO lattice |
Sun.pdf | manage | 689 K | 08 Feb 2008 - 12:36 | UnknownUser | FODO lattice presentation at ILCDR07-KEK | |
Wolski.pdf | manage | 4 MB | 27 Feb 2008 - 08:48 | UnknownUser | DCO lattice presentation | |
txt | k1FODO4-60degree.txt | manage | 756 bytes | 07 Nov 2007 - 11:30 | MarkPalmer | 60 degree phase advance lattice information (alpha = 6x10-4) |
txt | k1FODO4-72degree.txt | manage | 771 bytes | 07 Nov 2007 - 11:53 | MarkPalmer | 72 degree phase advance lattice information (alpha = 4x10-4) |
txt | k1FODO4-90degree.txt | manage | 743 bytes | 07 Nov 2007 - 11:54 | MarkPalmer | 90 degree phase advance lattice information (alpha = 2x10-4) |
xsif | kvals.108deg.xsif | manage | 2 K | 08 Feb 2008 - 12:29 | UnknownUser | Magnet strengths for DCO 100 deg lattice |
xsif | kvals.72deg.xsif | manage | 2 K | 08 Feb 2008 - 12:28 | UnknownUser | Magnet strengths for DCO 72 deg lattice |
xsif | kvals.90deg.xsif | manage | 2 K | 08 Feb 2008 - 12:28 | UnknownUser | Magnet strengths for DCO 90 deg lattice |
lat | ocs8.lat | manage | 11 K | 07 Nov 2007 - 11:25 | MarkPalmer | OCS8 Lattice File |
xsif | ocs8.xsif | manage | 11 K | 08 Feb 2008 - 12:25 | UnknownUser | Updated OCS8 lattice file |
Topic LatEvalPage .
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Revision r9 - 05 Mar 2008 - 22:52:39 - MarkPalmer
Parents: WebHome