[FFA_CEBAF_Collab] [EXTERNAL] Re: FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am

Fri Jul 1 10:04:50 EDT 2022

You'll have to reduce the number of full turns for a one-FFA solution with these constraints, because I tried basically that last year (a 4+7 turn solution) and got the 2T magnet.

But fortunately it seems 4+5 and 4+6 turn one-FFA solutions are quite good, as Dejan has found.

Also one of my solutions from last year, the 3+5+3 includes a 3+5 stage that gets to 18GeV in only a single FFA line.  This suggests 4+5 will likely get close to 20GeV.

--[If we decide to use two FFAs, say 4 +3, as a staged approach the second FFA could go into the ‘6th beamline shelf’]--

Agree this is a good way to do a further energy upgrade, which depends on how interested people are in the 20-25GeV region.

     -Stephen

________________________________________
From: Alex Bogacz <bogacz at jlab.org>
Sent: 30 June 2022 16:28
To: Brooks, Stephen
Cc: Ryan Bodenstein; Trbojevic, Dejan; ffa_cebaf_collab at jlab.org; Douglas Higinbotham
Subject: Re: [FFA_CEBAF_Collab] [EXTERNAL] Re: FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am

My quick reaction, interspersed below in ‘RED’

Cheers,

Alex
___________________________________
S. Alex Bogacz,
Accelerator Physics Group Leader
Center for Advanced Studies of Accelerators
Jefferson Lab
12000 Jefferson Avenue,<x-apple-data-detectors://8>
Newport News, VA 23606<x-apple-data-detectors://8>
___________________________________
Sent from my iPhone

On Jun 30, 2022, at 3:37 PM, Brooks, Stephen <sbrooks at bnl.gov> wrote:

Continuing to think about the design constraints, of my five, these two can be optimised by the lattice people:

- How many full turns in total? (9/10/11)
11
- Make the East and West FFAs different? (answer likely yes)
Y

But these three require answers from JLAB:

- 1090MeV linac or 1200MeV?
1090 MeV
- How many EM passes before the first FFA? (3/4/5)
4
(This one is related to the availability of a 6th beamline "shelf" in the arcs)
If we decide to use two FFAs, say 4 +3, as a staged approach the second FFA could go into the ‘6th beamline shelf’
- Tunable energy range and if so how much? (0-15%)
10-15%

Think of it like: a single FFA will give you ~19GeV but each of these three concessions (linac upgrade, 6th shelf, no tunability) gives you very roughly +2GeV in energy.

Then JLAB have to decide how much energy they want vs. these concessions.

NB: Dejan assumed no tunability, or perhaps tunability but only upwards in the linac energy (so assuming the linac upgrade instead!)

    -Stephen

________________________________________
From: FFA_CEBAF_Collab <ffa_cebaf_collab-bounces at jlab.org> on behalf of Brooks, Stephen via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org>
Sent: 24 June 2022 15:25
To: Ryan Bodenstein; Alex Bogacz; Trbojevic, Dejan
Cc: ffa_cebaf_collab at jlab.org; Douglas Higinbotham
Subject: Re: [FFA_CEBAF_Collab] [EXTERNAL] Re: FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am

Quick reminder of constraint choices determining the CEBAF FFA arcs:

- 1090MeV linac or 1200MeV?
- How many EM passes before the first FFA? (3/4/5)
- How many full turns in total? (9/10/11)
- Tunable energy range and if so how much? (0-15%)
- Make the East and West FFAs different?

Of these, 1200MeV linac, more EM passes, fewer full turns (i.e. lower output energy), no tunability and making the East/West different - all make the FFAs *easier* (higher field magnets).  The opposite choices make the FFAs harder.

For my 2021 design, reported in IPAC'22 recently, I made the following choices:
- 1090MeV linac
- 3 EM passes
- 11 full turns
- Full tunability
- East and West FFAs identical.

These all make the FFAs harder!  In the case of the fifth one, there's no reason to do this other than me not wanting to double the number of lattices I had to build.  So basically my design is conservative at the same time as trying to get the maximum functionality and not needing the 6th "shelf".  But could be improved slightly by separate optimisation of East and West.

If you relax the constraints, you can do better.

EM passes is interesting:
3 = can upgrade to two FFAs without 6th shelf, but lower performance
4 = can get first FFA without 6th shelf but need it for the second FFA
5 = can only do one FFA, second FFA would require removal of an EM line

So to me selecting 4 seems quite good here if there's any real chance of using the 6th shelf in the future.

Number of full turns determines the output energy:
9 = 19.x GeV or 21.x GeV with the 1200MeV linac
10 = 21.x GeV or 23.x GeV with the 1200MeV linac
11 = 23.x GeV or 25.x GeV with the 1200MeV linac

My old single-FFA solution that required difficult 2.0T magnets was 4+7=11 turn design.  However, it looks like a less ambitious 4+5=9 turns would have much easier magnets.  Dejan was showing 5+5 today.  And a small bump in linac energy would have got us above 20GeV again, if that's enough.

Instead of 3+4+4, 3+5+3=11 schemes for a dual-FFA design, it's interesting to think about, say, 4+4+3 (still 11 turns but uses the 6th shelf in the dual-FFA upgrade).  Next week I might look for lattices for this.

    -Stephen

________________________________________
From: FFA_CEBAF_Collab <ffa_cebaf_collab-bounces at jlab.org> on behalf of Trbojevic, Dejan via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org>
Sent: 24 June 2022 13:45
To: Ryan Bodenstein; Alex Bogacz
Cc: ffa_cebaf_collab at jlab.org; Douglas Higinbotham
Subject: [FFA_CEBAF_Collab] [EXTERNAL] Re:  FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am

Dear All,

I uploaded the files in Bmad with instructions how to run it. I did not write details of the ‘tao’ commands like ‘show lattice’, ‘view 3’ (show the results from the universe 3 or energy 3, ‘show element’ and so on as you can find these instructions in the tao Manual or Bmad Manual on the WEB. I also uploaded the EXCELL files where I calculated the synchrotron radiation losses.

Have fun,

Best from,

Dejan

From: FFA_CEBAF_Collab <ffa_cebaf_collab-bounces at jlab.org> on behalf of Ryan Bodenstein via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org>
Date: Friday, June 24, 2022 at 12:10 PM
To: Alex Bogacz <bogacz at jlab.org>
Cc: ffa_cebaf_collab at jlab.org <ffa_cebaf_collab at jlab.org>, Douglas Higinbotham <doug at jlab.org>
Subject: Re: [FFA_CEBAF_Collab] FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am
Hello colleagues!

Thanks for an exciting meeting. I think we can all look forward to what will grow out of this exchange. You’ll find the minutes attached to this email, as well as uploaded to the shared folder.

Have a great weekend, and we’ll talk again next week.

Cheers!
Ryan

From: FFA_CEBAF_Collab <ffa_cebaf_collab-bounces at jlab.org> on behalf of Alex Bogacz via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org>
Date: Monday, June 20, 2022 at 6:30 PM
To: Alex Bogacz <bogacz at jlab.org>
Cc: ffa_cebaf_collab at jlab.org <ffa_cebaf_collab at jlab.org>
Subject: [FFA_CEBAF_Collab] FFA at CEBAF WG mtg. this Friday, June 24 at 11:00 am

Dear Colleagues,
We will resume our design efforts on Friday, June 24 at 11:00 am.
*  Synchrotron Radiation calculation  –  Dejan
*  IPAC’22 impressions  – Stephen and Ryan
*  AOB – All
Please, follow a ZOOM invitation below.
Cheers,
Alex
___________________________________
S. Alex Bogacz,
Accelerator Physics Group Leader
Center for Advanced Studies of Accelerators
Jefferson Lab
12000 Jefferson Avenue,<x-apple-data-detectors://8>

ZOOM connection:

The link is here: https://urldefense.proofpoint.com/v2/url?u=https-3A__jlab-2Dorg.zoomgov.com_j_1614898082-3Fpwd-3DTnUzMS81M2sxbDZIbERJU01tYkJCQT09&d=DwIF-g&c=CJqEzB1piLOyyvZjb8YUQw&r=Ogg4WFNBwvADBq3fkmCLiJ7SaRDPYtawHzJElJMB0jE&m=YEQH-1vPGY0_hwTB5a-8w6fOLWDsAaIPdI2OXpr_3ZH1lXIxJAcdUocoG0kKt1Oh&s=BKquMzuFC3XNQ2S-fR0nmGhkJaGxiEs3-D9RjcoAQ-0&e= <https://urldefense.com/v3/__https:/jlab-org.zoomgov.com/j/1614898082?pwd=TnUzMS81M2sxbDZIbERJU01tYkJCQT09__;!!P4SdNyxKAPE!F8uSrkdBjdVx0vjaMTaSIbqECTVvXKb_NE2LkbEQcgJZJXv81hD8jTCHBvIvRE5fqjZILa6X-IAjIJRRaq-us4i9EwFY$>

In case of problems, the zoom room is below:
Meeting ID: 161 489 8082
Passcode: 123456

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