[FFA_CEBAF_Collab] [EXTERNAL] Re: FFA at CEBAF WG mtg. this Friday, Feb. 25 at 11:00 am

[Brooks, Stephen]

I'm open to changing in various ways.  Particularly, Labour<->Hardware can be freely interchanged at this point, and labs can redistribute among their own projects too.  Redistributing Year1<->Year2 requires balancing it by redistributing something in the other direction (I'd suggest the tracking).

Remember:
1.  These cash values all have the lab overheads;
2.  The chamber in the FFA may be narrow vertically but wide horizontally, we should test that;
3.  beta=500m is not representative of the FFA, our beta will be much smaller;
4.  We may do something a bit more ambitious than installing a single pipe: we could make one with an adjustable vertical aperture for example, like a movable collimator.  That would give more insight, rather than just "beam did/didn't go through" for a single value.  You may also have to buy some radiation monitors to detect beam loss although perhaps those can be borrowed from CEBAF.

Generally I anticipate the FFA tube will have a horizontal inner diameter of over an inch, but the vertical inner diameter could be as small as 6mm in some extreme cases.

     -Stephen

________________________________________
From: Jay Benesch <benesch at jlab.org>
Sent: 25 February 2022 15:17
To: Brooks, Stephen; ffa_cebaf_collab at jlab.org
Subject: Re: [FFA_CEBAF_Collab] [EXTERNAL] Re: FFA at CEBAF WG mtg. this Friday, Feb. 25 at 11:00 am

Stephen,

I would say $50K each for materials and labor on the CEBAF aperture item
is ample.  I suggest you place the $100K saved in lattice definition.
Much of the labor will be figuring out where to put a reduced diameter
tube.  Or perhaps only $10K materials and $50K labor vs $100K each.  The
tube itself will be cheap.  The installation labor will be of order
$10K.  The remainder of the labor will be figuring out where to put the
tube.

I note that the differential pumping stations at the end of each linac
contain slotted tubes 1.125" OD, 0.065" wall, aka 0.995" ID.  The one at
the end of the North Linac, where the beta is ~500 m on fifth pass and
geometric emittance ~2 nm, is activated at the end of each run.  And we
recently have had a few hot spots in the arcs in 1" OD, 0.065" wall (22
mm ID) tube running through quads.  Given the much larger emittance due
to SR in the higher energy FFA, it's not clear to me that the aperture
can be reduced significantly.

Jay