E-rhic-ir-l mailing list

[Bill Christie <christie AT bnl.gov>]

Dear All,
    Below please find the minutes from our eRHIC IR Design meeting that 
was held on Friday, 7/27/2018. Please note that our next meeting will be 
on Friday August 10th, at 3 pm.
    Greetings,
        Bill

  Minutes from the eRHIC IR Design meeting held on 7/27/18
 
---------------------------------------------------------------------------------
* We started with a brief discussion of the agenda for the meeting.
* Brief discussion and presentation by Vadim and Elke on a response to a 
request from Bob Tribble concerning eRHIC luminosities and luminosity 
lifetimes.
    - Vadim walked through the slides that he and Elke had put together.
    - In the discussion it was decided to remove the information/row 
for the number of running weeks per year. This number will rely on 
future operations budgets, and unknown at present.
    - The tables presented, along with Elke's spreadsheet, will be sent 
to Bob Tribble.
* We then walked through a presentation by Doug on integration into the 
RHIC tunnel (attached file 6IR Layout Development Update 2018-07-27.pptx)
    - Shows 6:00 IR layout with a 22 mr crossing angle
    - Walks through series of slides
    - Includes the Rapid Cycling Synchrotron (RCS) version 11
    - There is a discussion about how many crab cavities, and how many 
crab cavity cryo enclosures. Qiong will provide this information to Doug.
    - Point comes up that the ring frequencies are being discussed 
again for possible change.
    - Discussion of how the magnets integrate into the exiting RHIC 
ring (i.e. where beams go back into existing RHIC ring magnets)
    - In the discussion on how to reduce the cost for the IR design, 
integrate the IR magnets and RCS into the RHIC tunnel, and match the 
beams back into the existing RHIC ring magnets expected to be used in 
eRHIC, the three parameters to vary/optimize are:
        - Translate the collision point in the IR (radial translation 
was discussed)
        - Rotate the entire IR magnet setup about a vertical axis 
through the collision point.
        - Change/increase the crossing angle.

DESIGN STUDY PHILOSOPHY:
    The discussion about changes to the "Baseline" eRHIC design, which 
is what appears in the pCDR, led to the following philosophy. We'll 
embark on design studies of how to optimize (reduce) the cost, and ease 
the integration and matching into the RHIC rings, of the IR design. No 
changes will be introduced/adopted into the current "Baseline" design 
however until a more formal process is agreed upon, and then followed. A 
likely scenario is that once we believe that we have a better IR design, 
with essentially all issues investigated, addressed, and resolved, that 
we'll propose a formal change to the baseline design. When this occurs, 
the formal eRHIC design change formalism will be followed.

     - We discussed and decided that of the three parameters discussed 
above, for the design study venture, we'll take as the working crossing 
angle 25 mr (Baseline design crossing angle is 22 mr).
    - We discussed a bit whether we could set limits on the likely 
range of the IR Design rotation angle. Agreed that the limits were 
between 5 and 10 mr.
    - In looking at Doug's #D renderings of the IR and RCS design in 
the RHIC IR region, the question came up whether the RCS was a "flat" 
ring vertically (i.e. lies in a single horizontal plane). Answer was 
that yes, it is a flat ring, and in the present design it resides 0.5 m 
above the RHIC rings.

* Discussion of the next meeting:
    - Next meeting in two weeks on Friday, August 10th.
    - Draft Agenda:
        - Update from Doug on Integration
        - Update on the designs by Bob and Holger
        - Summary from the EIC Users meeting
                            End of meeting

Attachment: 6IR Layout Development Update 2018-07-27.pptx
Description: application/vnd.openxmlformats-officedocument.presentationml.presentation