E-rhic-ir-l mailing list

[Bill Christie <christie AT bnl.gov>]

Dear All,
    Below please find the minutes from our meeting on December 8th.

    eRHIC IR Design Meeting minutes
    ---------------------------------------------
          Meeting date: December 8, 2017.

Starting discussion:
    - Bill reiterated that at the last meeting he'd personally attended 
(11/4) that an issue had been found in the linear optics matching with 
the electron beam, and that the validity of the current IR design was 
uncertain. A main topic for this (12/8/17) meeting is to discuss where 
things now stand, and if possible, push to define and document a 
modified (as necessary) baseline IR design.
    - A second goal for the meeting is to look at issues relevant to 
the vacuum chamber/beam pipe design and constraints. Charles Hetzel 
joined us at this meeting to get a start on understanding these issues.

Walk through of Bob Palmer's presentation:
    - Bob sent a presentation to the meeting list the afternoon of the 
meeting. The title of the presentation is "Dec 17 IR Update"
    - Notes on Slide #3: the table dealing with the 18 GeV electrons 
has not yet been updated and checked. Will be updated.
    - Slide #4: What's shown are Bob's beta functions. They have not 
yet been tuned/matched to the lattice. Steve Tepikian will be working to 
determine the final beta functions.
    - Slides #5 and 6: Show synchrotron radiation fans, and where they 
end up. The magnet apertures shown on Slide 6 are rough approximations, 
and need to be corrected/updated.
    - Slide #7: Again, these are Bob's beta functions, and will be 
checked and updated to final values by Steve T.

>>>  Interjection of near term need and schedule by Ferdi:
    - By the end of next week (i.e. by December 15th) the goal is to 
have a "final" set of magnet parameters and geometry/locations, as well 
as a beam parameters. Also to have a geometry figure showing both the 
forward and rear regions of the IR design.
    - Brett raised the point that the actual beam pipe, helium 
enclosure, and cryostat designs for some of the magnets will require 
actual design to be precise. The idea for this stage is that Brett will 
come up with his best concept on what the magnet openings/apertures will 
be for these magnets, and attach some brief text both reminding the 
users of this information that it requires real design effort, as well 
as summarize what he assumed in his conceptual design.
    - As there will not be a meeting on Friday Dec. 15th, people who 
will be updating the relevant tables, plots, or figures, are asked to 
please send these updates to the mailing list, and Bill will "parrot" 
them back out as being the "final" versions if/as needed or beneficial. 
Best would be if when people send the updated versions to the list that 
they clearly note that they are the final versions.
>>>

Back to Bob's presentation:
    - Slide #9: For the hadron table shown on this slide, by next week 
there will be one set of numbers for the "Gradient (T/m)" column. The 
table will also be checked. The electron table will be checked, updated 
as needed, and finalized by a combination of Steve, Brett, and Bob.
    - Slide #10: Vacuum Outline
        - a "luminosity box" is shown. Elke points out that the design, 
and then space requied, for the luminosity monitor still needs to be 
worked out and detailed.
        - Bob makes some comments on what the vacuum pipe/chamber 
through the detector has to look like, describing where the warm to cold 
transitions, flanges, etc. may have to be placed.
    - Slides #11 & 12:
        - Shows some of the issues with fitting in the bellows and 
flanges that might be required for the vacuum pipes.
        - Comment that the actual radial thickness of some of the large 
diameter flanges shown may be thicker than shown.
        Some discussion that it may be necessary to have welded 
connections for the beam pipes in some of these regions. Somehow with a 
design that allows for cutting to open, and then re-welding the connections.
    - Slides #13 & 14:
        - Elke makes the point hat what is shown in the figures as "Tag 
1" is not needed.
        - Question comes up about the labeling of some of the magnets 
in the latest plots and tables with "C" instead of "B". The "C" denotes 
that these are now combined function magnets.

* Discussion of the next meeting date:
    - Conclusion is that the next meeting will occur on January 5th.
* Preliminary Agenda for the next meeting:
    - Brief discussion and summary of the final parameters for the 
magnets and beams, as well as forward and backward IR design geometry.
    - Charles reports on vacuum chamber design thoughts/design/status
    - AOB
                        End of meeting