[FFA_CEBAF_Collab] CEBAF 4-hall ops

[Todd Satogata]

Hi folks,

Per this morning's discussion, here is the canonical 4-hall beam
delivery paper from Reza et al:

https://accelconf.web.cern.ch/IPAC2013/papers/thpfi091.pdf

I also have a slide I often showed at the GlueX (Hall D) collaboration
meeting that I'm attaching here that shows some of the gymnastics on
one slide for even three halls. Note that there are three RF frequencies
that are harmonically related (f=1497 MHz for main RF, and f/3=499 MHz
and f/2=748.5 MHz for transverse separators); there is also an overall
bunch periodicity that is f/6=249.5 MHz.

- Filled B/C/D boxes at the top indicate intended bunches; the open
   boxes are "symmetric" partners that should have no beam (but sometimes
   have small beam due to laser afterglow)

- Lasers/bunches run at f/6=249 MHz (yet another harmonic!)

- The orange f/3=499 MHz lower pass shown kicks C and D one direction
   (into a recirculation channel, the orange double-headed arrow), and
   kicks B a different direction (to an extraction septum and then onwards
   to Hall B).

- The green f/2=748.5 MHz 5th pass shown is missing B (it was extracted
   earlier), but kicks C and D in opposite directions -- D recirculates
   to the 6th pass of the north linac, and C goes through the septum and
   onwards to Hall C.

- The green arrow shows that Hall D also gets the "empty" C' bucket
   in this scheme; beam accidentally in this bucket was "bleedthrough"
   to Hall D that was creating some issues discussed at the GlueX
   collaboration meeting.

It is all quite elegant, and not at all obvious how the different
harmonics interact, hence the picture that overlays the f, f/2, f/3
beam repetition and separator signals I put together to make clear
how the separators are intended to be phased in at least one configuration.

                                                 -Todd

======================================================================
Todd Satogata
Director, Center for Advanced Studies of Accelerators
Jefferson Lab
12000 Jefferson Avenue
Newport News, VA 23606
Cell: (631) 807-0674
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