Subject: AC homework questions and answers -- complete
From: "Peggs, Stephen G" <[email-masked]>
To: Shinji Machida <[email-masked]>, "Fischer, Wolfram" <[email-masked]>, Sergey Belomestnykh <[email-masked]>, "Harrison, Michael" <[email-masked]>, oliver bruning <[email-masked]>, Dave Rubin <[email-masked]>
Cc: "Trbojevic, Dejan" <[email-masked]>, Stephen Brooks <[email-masked]>, John Dobbins <[email-masked]>, georg hoffstaetter <[email-masked]>, "Michnoff, Robert J" <[email-masked]>, "Tuozzolo, Joseph E" <[email-masked]>, David Burke <[email-masked]>, "Richard E. Gallagher" <[email-masked]>, Adam Christopher Bartnik <[email-masked]>, Colwyn Gulliford <[email-masked]>, "Peter G. Quigley" <[email-masked]>, "Berg, J Scott" <[email-masked]>, Nilanjan Banerjee <[email-masked]>
Date: Fri, 23 Feb 2018 13:58:23 +0000

AC panel,

here is the complete set of homework questions and answers.  See you at 9 am.

Steve

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Q1) Can you elaborate on the SBIR proposal for instrumentation, and what happens if they say no.  Is there a ranking of the wish list ?

A1) GEORG:

The proposals are:
1) SBIR II to DOE-NP for a laser wire scanner, currently under consideration.
2) SBIR I to DOE-HEP for a halo monitor, currently being submitted.

There is no backup. If they do not get funded, we have not scheduled funds and R&D time for these detectors. If (1) does not get funded, we would have to live with whatever beam size we will get, as long as it fits through the vacuum chamber. Very interesting emittance growth studies could then not be done. If (2) does not get funded, we would analyze the halo by means of radiation rates along the accelerator and we would minimize these rates to minimize Halo losses. Again, much insight would be lost.

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Q2) What is the projected operation cost for running the facility as a user facility ? (per month)

A2) KARL:

Current estimates for monthly operations costs (from the recent proposal for DOE NP) are approximately $250,000/month.  This is a bare bones operations cost including electricity, cryogens, control room operations staff only, and basic maintenance of equipment.  A more realistic estimate would be $350,000 - $400,000 / month, which would support additional staff that may be required to run a user facility.  Note that Cornell construction costs are unburdened by overhead, but Cornell operations are burdened by a 63% overhead.

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Q3a) What is plan B for the FAT ?  Which pieces can you live without ?

A3a) GEORG:

Plan B is to install successively 6 dipoles and steer the beam from screen to screen. We have 3 BNL-ERL dipoles and suitable power supplies and only need 3 new splitter-line dipoles for this. No quadrupoles would be needed. Studies show that this would lead to sufficient beam current to be detected after the permanent magnets of the FAT.

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Q3b) What comes after NYSERDA milestone - goals for the FAT before dismantling it.

A3b) ADAM:

Let's assume that we've achieved the NYSERDA milestone with the minimum amount of effort and understanding-- that is, we simply got a spot on the final viewscreen at the end of permanent magnet (PM) girder. We could easily have gotten to this point without having spent any time doing careful calibration of magnets, having spent no time investigating path length adjustment, or doing any sort of optics verification. That is, after the milestone occurs, the real work can finally begin. But at this point, the path separates depending on whether we've gone down some sort of "plan B" path, or if we have an honest splitter. I have little interest in investigating temporary magnets, or characterizing a beam going through them. So, for the sake of brevity here, let's assume that we have a real splitter, and everything has been installed. Assuming that, here is a wish list of goals that I would like to shoot for.

Goal 1) A well-understood MLC, with the following goals:
• An established procedure to turn on the cavities, and achieve target operating voltage (with controls for non-experts.)
• Cavity field calibrated using the beam
• Full range of stable operating voltages determined.
• Understood cryogenic loads, microphonics compensation working
Goal 2) A well-understood S1 section with the following goals:
• Dipole and quadrupole magnets calibrated
• BPMs and BAMs working (that means: position nonlinearity understood, procedure to "time" the BPMs well-defined, accuracy versus charge/current studied)
• A procedure is defined and tested to measure/correct the machine response to all splitter dipoles and MLC energy gain. This means a position response measured with BPMs, and time response from BAMs.
• A "baseline" machine setting determined that best matches the expected response, as measured above
• Path length adjustment working as expected, and a verified way to correct the orbit while adjusting the path length.
• A beam profile on the final splitter viewscreen that meets expectations
Goal 3) A well-understood PM girder with the following goals:
• A well-defined method to find the best periodic orbit through the PM sections
• At 42 MeV, a study of the injection orbit acceptance (entrance position and angle)
• Above 42 MeV, a study of the energy acceptance
• Response measurements at each BPM to dipoles in the splitter for optics verification
• Finally, a bunch on the final viewscreen that meets expectations
(Note: a well-tuned beam size may be below the measurement resolution-- but a badly matched beam will be easily measured)

Now, although we have an existing plan that allocates time for each of these goals, the duration of these beam experiments and (more importantly) the very layout of the FAT machine is still not determined, and that plan is perhaps likely to change and possibly have its scope reduced. If the scope is reduced, I would prefer first that the MLC is fully characterized, and then that as much of the PM girder studies are completed as possible-- with whatever beam we can deliver to them.

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Q4) Is there any collaboration with bERLinPro ?

A4)  GEORG:
• Georg is on the BERLinPro MAC and have been on since its inception 6 years ago.
• Ritchie Patterson is on an HZB advisory committee, not the one for BERLinPro. But they consider the ERL amongst other things.
• Cornell has had an MOU for about 15 years. It is worth checking that it has not expired.
• The MOU was used for collaborations on SRF field control studies in their test cryomodule (about 10 years ago).
• The MOU was used for collaborations on SRF tuner studies, comparing three tuner designs to help us make a good choice for the MLC (about 8 years ago).
• The MOU was used when they ordered HOM absorbers from us. We produced and delivered these (about 3 years ago).
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Q5) How much of the cBeta V software will be available/used in the FAT?

A5) COLWYN:

The short answer is that all of it will be available and used in the FAT.  The majority of the software is written and already tested or is currently being tested now.  The save/restore module is complete, the CBETA-V EPICS records are live, and the virtual machine application already can be used to look at difference orbits - the orbit bump measurements shown in the presentation were with the machine on taking real data and comparing to CBETA-V in real time.  The orbit correction is also probably already working it just, we just need a little more help form Dave Sagan in learning the correct commands to run it.  Of course I'm sure there are likely still bugs to iron out, and the FAT will make a perfect test ground to check the software with a real machine.

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CBETA Project Director
+1-631-344-3104  work
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“Introduction to Accelerator Dynamics” — http://www.cambridge.org/9781107132849