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

[Jay Benesch]

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