E-rhic-ir-l mailing list

["Christie, William" <christie AT bnl.gov>]

Dear All,
       Below please find the minutes from our eRHIC IR Design meeting that 
was held on Friday, 11/9/2018. Please note that it was decided that our next 
meeting will be on Friday November 16th, starting at 2:30 pm.
       Greetings,
           Bill

     Minutes from the eRHIC IR Design meeting held on 11/9/18
    
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* We started with a brief discussion of the agenda for the meeting.
    - An update from Stephen T.
    - General comments and observations from people who attended the EIC 
collaboration mtg down at JLab.

* Brief update from Stephen T.:
    - Has been looking at placing the electron ring above the hadron ring.
      - The electron beam would be brought back down to the elevation of the 
hadron beam at the IRs to bring them into collision.
      - The beams are brought down to the hadron beam elevation about 6 m 
downstream of the Crab cavities.
      - A bit of general discussion about this idea/concept.
    - Stephen will put together a few slides for presentation at the next IR 
Design mtg.
    - Brett brings up the point that if one has a long straight section for 
the incoming electron beam hat there may be an issue with beam gas background 
making its way into the detector. Some comments that this background is 
likely small, and conclusion that an estimate needs to be done.

* Bob indicating that he is putting together the "new" design that was 
presented at the EIC collaboration mtg. Bill reminds group of our "Design 
Philosophy" (i.e. there is the baseline design in the pCDR, and we'll be 
fairly formal if a decision is made to change/evolve the baseline design).
   - Point was made that there is a need to get the Detector magnetic field 
included into the collider tracking studies and simulations.

* Discussion about people impressions and observations from the EIC 
collaboration mtg:
    N.B. This is a collection of statements made, some may be in conflict 
with one another.
    - "Not a bad mtg, but not particularly good"
    - "Not a lot of signs of "collaboration"".
    - Jlab assumes hat they can change to lower (< 4 cm) betas. A bit 
surprising that they show larger beta modes.
   => "We should collaborate on dynamic aperture studies".
    - The time constant for the required JLab cooling is ~ 30 seconds!
    - The current JLab pCDR design writing doesn't meet the agreed to Physics 
program requirements.
       - They are writing an Appendix that does meet the Physics program 
specs. This leads to their required magnetic field strengths getting 
extremely large.
       - Difficult for them to run the high energies.
** JLab agrees with BNL that there is a Goal/need to have a common IR design 
requirements document, which enables/supports the Physics program.

*** Elke, in discussions with Ric Y., agreed that it is very difficult to get 
the Users group community involved/engaged in defining these requirements.
    - "Thought it was a good meeting".
  * Brett indicated that the idea came up that there should be more frequent 
meetings between the two EIC efforts, with smaller "limited" scopes, e.g. on 
Polarimetry (already scheduled), etc.

* Discussion of date for next meeting:
    - It was decided to have the next meeting in one weeks time, on Friday 
November 16th, starting at 2:30 pm
    - Elke graciously volunteered to run this next meeting.
    - Preliminary Agenda:
       - Stephen will give another update, and show a few slides
       - Bob will give an update on his Tech note
       - Brett suggests a discussion be had on "Whether or when the new 
design is stable", and hence should have a more detailed simulation study.

                End of meeting.