[FFA_CEBAF_Collab] [EXTERNAL] Re: re JLab/BNL FOA response

[Jay Benesch]

Stephen,

I think the 1200 MeV racetrack was your idea as it allows the 
electromagnets in the West Arc to be used as is.  I have no objection to 
altering it.

I sent the document out in the hope that the group could arrive at a 
consensus by noon Friday and get started on writing the FOA response on 
the basis of that consensus.  Although I'd like some weasel-words in the 
response in case we come up with a much better idea than the present 
baseline A+1 ;-)

I am pleased to learn that window-frame magnets big enough to fit over 
the permanent magnets can provide roughly the necessary steering fields. 
  I trust they have a steel return outside the picture frame so the 
return fields from the first FFA's steerers don't affect the second 
centered 50 cm below.

Jay

On 3/7/22 13:36, Brooks, Stephen wrote:
> Also, in Jay's slides is there any reason why the rather complex 1.2GeV injector idea can't be replaced by the 650MeV single-loop injector throughout?  Is it because you wanted electrons and positrons simultaneously?  I don't see any disadvantage otherwise, unless you specifically wanted 1.2GeV.
> 
>       -Stephen
> 
> ________________________________________
> From: Brooks, Stephen <sbrooks at bnl.gov>
> Sent: 07 March 2022 13:33
> To: Jay Benesch; Georg Heinz Hoffstaetter
> Cc: ffa at cebaf; Camille Ginsburg
> Subject: Re: [FFA_CEBAF_Collab] [EXTERNAL] Re:  re JLab/BNL FOA response
> 
> Providing a dipole correction is in principle very easy with gradient magnets, since you can shift the magnet physically by a small distance.
> 
> 18000 G.cm = 0.018 T.m = ~0.01 T Or less over the length of a typical CEBAF FFA magnet.  At 40T/m that's a 0.25mm shift.  I'm not 100% familiar but I think there are "piezo" movers that can be electrically operated to expand and contract over such small distances.  Although levers and gears and motors would be possible too...
> 
> I'm reminded that CBETA's windowframe correctors that wrapped around the magnets could provide something like 0.02T or 1280G.cm, equivalent to a 2mm shift of the whole magnet (!)  So that's another possibility.  And those correctors were only 10-15cm long, same as the magnets.  For CEBAF FFA, our magnets are order of 2m long.  The permanent magnet is transparent to the field from the windowframe outside.
> 
>       -Stephen
> 
> ________________________________________
> From: FFA_CEBAF_Collab <ffa_cebaf_collab-bounces at jlab.org> on behalf of Georg Heinz Hoffstaetter via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org>
> Sent: 07 March 2022 09:25
> To: Jay Benesch
> Cc: ffa at cebaf; Camille Ginsburg
> Subject: [FFA_CEBAF_Collab] [EXTERNAL] Re:  re JLab/BNL FOA response
> 
> Hi Jay,
> 
> Is there space to put the correctors in-between the permanent magnets?
> 
> Best,
> Georg
> 
> 
>> On Mar 7, 2022, at 8:54 AM, Jay Benesch via FFA_CEBAF_Collab <ffa_cebaf_collab at jlab.org> wrote:
>>
>> Colleagues,
>>
>> I created the attached to clear up in my own mind what the options are.  This may assist in writing the FOA response.
>>
>> The last two slides may throw a large wrench into the whole exercise.
>>
>> Jay <FFA_options_benesch_7mar2022.pdf>_______________________________________________
>> FFA_CEBAF_Collab mailing list
>> FFA_CEBAF_Collab at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/ffa_cebaf_collab
> 
> 
> _______________________________________________
> FFA_CEBAF_Collab mailing list
> FFA_CEBAF_Collab at jlab.org
> https://mailman.jlab.org/mailman/listinfo/ffa_cebaf_collab