E-rhic-ir-l mailing list

[Aschenauer Elke-Caroline <elke AT bnl.gov>]

Dear Charles, Dear All,

first of all Happy New Year to all.

Great to see the vacuum pipe makes such nice progress.

Reading through the emails I have first one question how much safety margin have we foreseen that the SR fan can move without hiding the flange or the beam pipe at the end of the detector.

And yes indeed before we would like to move the flanges into the detector we would need to know what the size is as this will cut into the low Q2 acceptance of the detector which is critical for the saturation physics, one of the key physics programs at an EIC.

Cheers elke

On Jan 4, 2018, at 12:15, Palmer, Robert <palmer AT bnl.gov> wrote:

We do not propose a beam screen as LHC has, so it may not be quite so complicated. Do we have details of the RHIC cold-warm transitions?

 

From: Hetzel, Charles 
Sent: Wednesday, January 03, 2018 7:24 PM
To: Palmer, Robert <palmer AT bnl.gov>
Cc: Montag, Christoph <montagc AT bnl.gov>; Parker, Brett <parker AT bnl.gov>; Alexander Kiselev <kisselev AT mail.desy.de>; Aschenauer, Elke <elke AT bnl.gov>
Subject: RE: opening angles

 

Unfortunately it is not that simple. We need to keep the beam vacuum and insulating vacuum separate and leave room for thermal shields between the cold mass and the cryostat. Going through papers from CERN, their most aggressive cold to warm transition is 30cm but all details I come across appear to be more like 50cm. We might be able to shorten this if we can accept a higher load but this will all depend on the detailed design. Here is a sample of a typical warm to cold transition with a 20K actively cooled beam screen just to give you an idea of what this will need to look like. The bellows shown are only accommodate movement between the cold mass, cryostat and ridged beam tube.

<image001.png> 

For now I have only been working on the rear side layout which I thought has 1m of space between the central detector region and C1R. I really think trying to squeeze a bellows and a cold to warm transition into .5m is going to be really hard and would need a close look into the details to see if it would be feasible.

 

From: Palmer, Robert 
Sent: Wednesday, January 03, 2018 3:54 PM
To: Hetzel, Charles
Cc: Montag, Christoph; Parker, Brett; Alexander Kiselev; Aschenauer, Elke
Subject: RE: opening angles

 

I had hoped that the bellows and warm-cold transition are one and the same. A bellows has a very low heat leak if the ends are at different temperatures, and would hopefully fit in the 0.5 m between the central detector and C1. If not, it would be a major change to move C1 up to 5.5 m. I doubt we want to do that now.

 

It would be good to talk to Alexander and Elke to see whether a bellows could extend into the end of the central detector. They would want to know what its outside radius would be. That goes for both ends, although it is more urgent at the rear (with 0.5 m) than the forward (with 1 m).

 

Bob

 

From: Hetzel, Charles 
Sent: Wednesday, January 03, 2018 2:23 PM
To: Palmer, Robert <palmer AT bnl.gov>
Cc: Montag, Christoph <montagc AT bnl.gov>; Parker, Brett <parker AT bnl.gov>
Subject: RE: opening angles

 

Thanks. I was just able to squeeze in 120mm wide @ 5m. Would have to go up another flange size to accommodate anything wider. Looks like we would need at least .5m for warm to cold transition (based on what I could find published not FEA) plus another .37m for rf bellows and some pumping/gauging. Could shorten the bellows a bit if necessary. Haven’t had as much time as I hoped to work on this.

 

Do you know if the cold bore for C1R needs to be tapered or could it be constant cross section through the cryostat? Guess this is a question for Brett. I don’t remember the proposed magnet geometry.

 

 

From: Palmer, Robert 
Sent: Wednesday, January 03, 2018 1:47 PM
To: Hetzel, Charles
Cc: Montag, Christoph; Parker, Brett
Subject: RE: opening angles

 

I have updated the ‘update’ and added, on p 7 formulae giving the radial ellipse dimensions. As drawn in p 28 the flange is  at -5.3 m giving fan radii of 6.6 in x and 2.0 in y giving full widths of 132 by 40 mm, which is a little larger in x but smaller in y. However there is a move afoot to reduce the synchrotron fan dimension I x by 10%, bring its width back to 118.8 mm close to your number. You should check with Christoph whether this change is official. The y dimension would not change.

 

The hadron inside radius in x is L*(m) x 0.22 in cm  and in y it  is L*(m) x 0.38 in cm.

 

Bob

 

From: Hetzel, Charles 
Sent: Wednesday, January 03, 2018 6:37 AM
To: Palmer, Robert <palmer AT bnl.gov>
Subject: opening angles

 

Happy New Year. Hope you enjoyed the holidays. Would you be able to let me know the H and V opening angles for the synchrotron fan DS of the IR? I am using a size of 120mm x 60mm at the flange joint shown on your slide 28 as a starting point.

 

Thanks,

Charles Hetzel

NSLS-II Project, Building 743

Brookhaven National Laboratory

(631) 344-5722

 

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