2017-10-30

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Director - M. Spata
No report


Accelerator Physics - T. Satogata


Accelerator R and D - Y. Zhang


Computational Physics - Y. Roblin

Yves Roblin: JLEIC: 

-Beam Beam simulations continued. Wrote tools to produce tune maps and FMA maps from BB3D output.  
-Models now include non-linear maps from the lattices. Longitudinal transport is modeled as linear. Still working on converting MAD-X/ELEGANT maps to BB3D reference frame for longitudinal optics.
-Preparing slides for talk on beam-beam results, starting gathering info to write the beambeam cdr chapter meetings with terzic et al regarding ghost development and upcoming paper.
-Setting up tools for dynamic aperture scan for the e- ring (with Fanglei)

CEBAF: 

-getting ready for fall run, reviewing optics, updating decks with new info.
-Reviewing procedure for the tritium experiments regarding the ion chamber calibrations
-Discussions with HLA of tool prioritization for this fall beam test plans (pathlength tool first)
-Hosted visit of the CEBAF injector for the IN2P3/CNRS French delegation

He Zhang:

  • Simulation for DC cooling in the collider ring with fixed bunch length - Did this simulation again and discussed the result with Jiquang. Different with the previous simulation, this time, as we fix the ion bunch length, we also double the change of the momentum spread due the cooling. The cooling effect was distributed evenly in both the changes of the bunch length and the momentum spread. Now if the bunch length is fixed, all the cooling effect is contributed to the change of momentum spread. After this change, the ion beam momentum spread decreases faster. But the equilibrium emittance and momentum spread remain almost unchanged.
  • Simulation for the IBS expansion for proton beam at 40, 100, 200 and 1000 GeV - Simulated the IBS expansion process (without cooling) for the proton beam with the latest parameters of highest liuminosity at 40, 100, 200 and 1000 GeV and discussed the result with Yuhong. (1000 GeV case is for comparision only.) If the transverse direction is fully coupled, it is clear that the higher the energy, the weaker the IBS effect and hence the less increase of the emittance, although the IBS rate only shows a weak dependence on the energy. But if there is no coupling, the horizontal emittance at the 200 GeV increases the most. This is because at the lower energy the vertical emittance increases more. Although the increase of the 4d emittance is inversely proportional to the energy, the increase of the horizontal emittance shows positive related with the energy. To get an idea of the coupling effect, simulations were done for 0%, 20%, 40% and 100% transverse coupling.
  • JSPEC development - Change the output format of JSPEC into text based SDDS format. As tested, the SDDS tools can read the output data from JSPEC. Since it is text SDDS format, not binary SDDS format, we can also easily load the file by other programs, e.g. python, if needed.
  • Paper on RF heat load and trip rate optimization - Redraw a few pictures as Balsa suggested. Submitted the paper to PRAB.
  • Paper on Cartesian tensor based FMM - This paper was rejected by JCP. One reviewer recommend “publish without future adjustment”. But the other reviewer rejected our paper simply because the scaling of the Cartesian tensor based FMM has a higher dependence on the rank of the tensor than other FMM kernels, such as the analytical FMM and the kernel independent one. I am not convinced by this review. This fact on the scaling is well known since 2007 when the first paper on Cartesian tensor based FMM was published. But the Cartesian tensor based FMM has been accepted as a piece of the FMM family and some state-of-the-art FMM library includes the kernel. I wrote a draft of the appeal letter. Waiting for some feed back from Li-Shi before I submit it.
  • Finished reviewing the paper for SISC.

Kirsten Dietrick:

  • Reading: PEP-II impedances, RHIC impedances, HLS-II impedances, RTFB transform, magnetized beam emittances (drift and Larmor)
  • Simulations: got 3D field map of C50, C100, 2-cell cavity from Haipeng, ran LERF injector with 1D and 3D maps of FEL booster (2xC50) and UITF/new CEBAF QCM booster (2-cell + C100), Haipeng sent 1- and 2-cell CEBAF separator cavities, evaluated different methods of calculating beam magnetization; three agree across simulations, confident in calculation (after Cooler meeting), currently have axially symmetric elements changing magnetization of beam, which may not be physical - currently evaluating
  • Impedances: working on impedance budget, pulling numbers from different machines
  • Meetings/Seminar:
-Impedance budget/calculation (Rui, Bob Rimmer, Frank Marhauser, Shaoheng Wang)
-Impedance budget/calculation (Rui, Tim Michalski, Mark Wiseman, Chuck Hutton)
-Cooler, presented LERF injector results - got questioned about validity of method used to calculate beam magnetization
-Seminar: Cockcroft Institute, Peter Ratoff
-Cooler, got assigned to simulate separator cavity/dipole combination in GTS (Andrew's merge idea, made simple)
-JLEIC
  • Misc:
-put in travel requests for IPAC'18 and LINAC'18 (ERL/FEL/COOL in 2019)

Next two weeks:

  • Reading:
-impedances from different machines
-why the magnetization is not preserved going through a solenoid of sufficient strength
  • Simulations:
-evaluate beam magnetization behavior through axially symmetric elements; when and why isn't it preserved?
-evaluate difference of maximum solenoid field on or off cathode; maybe talk to GTS group
-Andrew's GTS set-up (replace diagnostic beamline with superposition of separator cavity and dipole)
-verify accuracy settings in GPT
  • Impedances:
-continue pulling numbers from different machines
-start getting components unique to JLEIC calculated if modeled (or modeled if possible)
  • Meetings:
-Cooler (Nov. 6th)
-JLEIC
-Bas's visit (week of Nov. 6th)
-possibly Riad's group about beam magnetization


Diagnostic Development - K. Jordan

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