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[Vasiliy Morozov <morozov AT jlab.org>]

Dear All,

Yes, solenoid integration is an important issue that has not been fully resolved yet. It may be worth discussing it at the meeting. The issue is more complicated compared to what people dealt with in the past due to interplay of coupling and crabbing.

I think the problem with the vertical orbit angle at the IP that Alexander mentioned is not a big deal. If it causes any concern it can be easily fixed by addition of another weak y-kicker on the rear side of the ion beam line.

Recent work on the solenoid  integration had to do with revisiting the solenoid compensation scheme to see if we can get rid of the vertical crabbing cavities. They were initially introduced to disentangle crabbing and coupling but they may cause an unnecessary design complication and cost increase. Eliminating them does not seem to make a big difference for ions but the beam distribution at the IP may end up with unusual 6D correlations that need to be examined carefully from the detection point view.

Things are significantly more complicated for electrons. It looks like we need local solenoid compensation. One of the options is to use additional solenoids instead of vertical crab cavities. They could be placed outside of the detection area so that they would not interfere with the acceptance.

A somewhat related subject is control of the beam aspect ratio at the IP. One option that is being considered is to introduce controlled coupling at the IP to adjust the vertical electron beam size. This is probably not an issue for detection but it would still be better to check that the beam distribution does not cause systematic effects.

Best,

Vasiliy

---

From: E-rhic-ir-l <e-rhic-ir-l-bounces AT lists.bnl.gov> on behalf of Aschenauer Elke-Caroline via E-rhic-ir-l <e-rhic-ir-l AT lists.bnl.gov>
Sent: Friday, February 19, 2021 12:19 PM
To: Berg, J Scott <jsberg AT bnl.gov>; e-rhic-ir-l AT lists.bnl.gov <e-rhic-ir-l AT lists.bnl.gov>
Cc: Alexander Kiselev <kisselev AT mail.desy.de>
Subject: [EXTERNAL] Re: [E-rhic-ir-l] EIC IR Maturity Conversation @ the IR Meeting

 

Hi Hi,

this is important that the "friends of physics" really understand in detail where we stand on this becuase this can have a really major impact on our physics

Cheers elke

On Feb 19, 2021, at 12:10, Berg, J Scott via E-rhic-ir-l <e-rhic-ir-l AT lists.bnl.gov> wrote:

I think his compensation scheme has evolved significantly since then, this is probably the most significant issue to be dealt with from the lattice end. There are issues here with requiring magnets that we haven't planned for at this point, in particular having an additional solenoid field near the IR.

-Scott

-----Original Message-----
From: E-rhic-ir-l <e-rhic-ir-l-bounces AT lists.bnl.gov> On Behalf Of
Alexander Kiselev via E-rhic-ir-l
Sent: Friday, February 19, 2021 11:51 AM
To: e-rhic-ir-l AT lists.bnl.gov
Subject: [E-rhic-ir-l] EIC IR Maturity Conversation @ the IR Meeting

  Hello colleagues,

  in his talk during the crossing-angle-related meeting last October

https://indico.bnl.gov/event/9887/contributions/42722/attachments/30931/486
65/EIC_Ion_Sol_Comp_21oct20.pptx

Vasiliy reminded us that in the presently implemented solenoid
compensation scheme the vertical excursion of the hadron beam is
substantial, and (somewhat unfortunately) it results in a non-zero
vertical momentum component at the IP. Ideally, we do not want this.

  I believe Vasiliy said that the compensation can be implemented
differently, with the P_y(IP) = 0 condition observed. Can we add
a discussion around this matter to the agenda?

  Regards,
    Alexander.





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