E-rhic-ir-l mailing list

[Bill Christie <christie AT bnl.gov>]

Dear All,
    Below please find the minutes from our IR Design mtg that we had on 
November 3rd. Also please note that Vadim has kindly agreed to run the 
IR Design meeting this Friday, Nov. 17th, as I'll be away from the lab.

    Minutes from the eRHIC IR Design meeting held on 11/3/17
-------------------------------------------------------------------------------

* We started with an update on the Linear Design Optics. Guillaume 
wasn't present at the start of the meeting, so Dejan gave us a brief 
overview of what had been done.
   - This optics solution is for what Dejan described as a "new" 
baseline IR design. He explained that one or a few magnets had to be 
moved, and perhaps their field strengths changed, to get a good solution.
   - Bill reminded the group that we'd decided about a month ago that 
the baseline design would only be changed after discussion in one of our 
meetings. Also that the baseline had to be documented.
    - It was agreed that the baseline design will be revised to 
incorporate the latest changes, and presented at our next meeting. This 
task was assigned to Guillaume and Steve T.
    - It was further decided that the two single slide presentations 
which Brett sent around on 10/30 would be kept as a "backup" design.

    + At this point Guillaume joined us
   - He reiterated that by making a few changes to the IR design he was 
able to find a solution.
   - Includes ?? after B2 and before B3
   - Issue with phase advance (presented as "pi", instead of an odd 
multiple of "pi"/2, which would be a problem). After a bit of discussion 
it was concluded that this pi/2 was only part of the phase advance, and 
that the actual relevant phase advance was 3pi/2, which is fine, so no 
issue.

* Alexander gives us an update on the Geometry multiple format 
implementation.
    - No changes.

* We then went through a presentation which Bob Palmer had sent around 
today (11/3) Titled "G0 Ideas"
   - Discussed both the "Old" and "New" designs for the incoming 
electron beam.
   - Presented tables which detailed the differences between the two 
designs.
   - Ended with a slide listing downsides of new design, possible 
remedies for these downsides, and the question as to whether this is 
possible.

* At this point Ferdi raised the concern about the available dynamic 
aperture in the current IR design. It looked like the aperture in the 
current design was only about 6 sigma, which was not felt to be a design 
that one could present and defend. This lead to a discussion that the IR 
design would have to be revised, and how this should proceed. Some 
discussion about the minimum dynamic aperture that would be acceptable. 
I don't recall that an agreed spec. for this parameter was agreed to, 
but I believe the minimum would be on the order of at least 10 sigma.
   - The discussion ended with the idea that this would take some 
thought offline (i.e. after meeting).

* Presentation by Brett, sent out on 11/3, Titled "A Toroid Based 
Combined Function G0 Sweet Spot Magnet"
    - Showed a slide with the coil windings, the vertical Field 
profile, and then a summary slide of the advantages of this idea.
    - Unfortunately, I (minute taker) had to leave the meeting at this 
point for another commitment, and missed the end of this discussion, as 
well as the end of the meeting.
                >> End of Meeting<<<

    Agenda for the next meeting (Nov. 17th, a guess as I wasn't present 
at end of meeting to discuss):
   - A brief presentation by Guillaume and/or Steve T. on the new 
"baseline" IR design.
   - An update on the multiple geometry format software by Alexander.
   - Continuing discussion on revising the IR design to achieve an 
acceptable dynamic aperture.