2017-08-18

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Accelerator R and D - Y. Zhang Fanglei Lin •Optimized the hybrid multi bend achromat lattice for the electron collider ring with a similar arc bending radius to that in the baseline design and presented in the JLEIC R&D weekly meeting. •Worked on studying the chromaticity compensation and dynamic aperture in the electron collider ring and presented the results in the nonlinear beam dynamics bi-weekly meeting. •Continued working on the electron spin tracking using SLICKTRACK and ZGOUBI. •Working on preparing the presentation for JPoS17. •Miscellaneous: attended JLEIC weekly R&D meetings, attended the nonlinear beam dynamics bi-weekly meeting, discussed IP magnets with engineers.

Vasily Morozov •JLEIC planning: preparing a revised R&D plan •Ion polarization: testing Zgoubi and completing annual report •Geometry tagging LDRD: teleconference with collaborators and running simulations •Detector integration: integrating solenoid compensation scheme into the latest detector region design and discussion with engineers about the corrector design

Amy Sy •Confirmation that adding the fringe field kick to the magnetized beam distribution removes angular momentum from the beam, resulting in "quiet" beam transport through a solenoid field. G4Beamline does not include this fringe field component, so manual fringe field kicks are needed to approximate the effect of entering the real solenoid field. The inverse fringe field kick is added back to the distribution at the end of the transport channel, and the distributions at the entrance and exit of the merger section are compared. •With the fringe field kick effect included, the transverse properties of the low energy beam (5 MeV/c) are fairly well preserved. With space charge effects included, there is significant growth of the energy spread ~ order of magnitude for bunch charge of 3.2 nC). For the high energy beam (20 MeV/c), there is some growth in the transverse phase space, mostly in the vertical plane. With space charge effects included, the growth of the energy spread is on the order of a factor of 2 for the 3.2 nC bunch. •Working on incorporating the inverse flat beam transform for a direct comparison of horizontal/drift emittance and vertical/Larmor emittance before and after transport, and better approximation of fringe field kick for the high energy beam due to the off-axis injection into the merger.

Guohui Wei 

  sick leave

Yuhong Zhang • Attended meeting/discussion on bunched beam cooling experiment data analyses • Worked out a first program on eRHIC-JLEIC joint Collaboration meeting • Completed a set of slide for JPOS2017 talk and now it is merged to Fanglei's talk, discussed formation of polarized positron beam for JLEIC with Fanglei, Vasiliy and Jiquan • Started writing slides for two presentations: COOL17 and PSTP2017


Computational Physics - Y. Roblin
Yves Roblin:
JLEIC: 

  + Cooler ring meeting, discussions about Kirsten's workplan.
  + Assessing options for Beam-Beam with uneven harmonic numbers using GHOST
  + testing GHOST, adding needing features
  + setting up BB3D for gear  changing
  + Meetings regarding He Zhang Green card status

CEBAF: 

  + Preparing for JPOS, exploring positron option in CEBAF.

ADMIN: 

  + revised AWP for new funding supplement

Next two weeks: 

  + revise plan for simulation work, produce timelines and estimates
  + JPOS work, more GHOST/BB3D work

He Zhang:
JSPEC:

  • Text-based user interface and a tutorial text-based interface to JSPEC is finished. Wrote tutorial on how to use it. Wrote a suite of tests to check the code benchmarking it against BETACOOL again. All uploaded to GIT.
  • Improved model beam method. Proposed two different models. Both are being benchmarked. One of the models seems more promising. The other model suffers from a breakdown of the initial assumptions.

IMP:

  • Start developing turn-by-turn tracking for IMP experiment - Discussed with Shaoheng about how to simulate the IMP experiment. To minic the experiment, we decided to simulate two bunches, one cooled and one not cooled. According to his analysis, there are some ions that are not captured by the RF bucket and are moving freely inside the ring. These ions may be captured later if they are cooled. We want to simulate these particles too, and a model of the RF cavity, rather than a one-turn map, may be needed. I just started to work on the code.

Next two weeks work plan:

  • Continue developing the turn-by-turn tracking for IMP experiment
  • Continue testing the improved model beam method
  • Investigate the simulation of phase painting injection with IBS and cooling for Pb ion using BETACOOL
  • I would like to go back to work on the dust particle transfer problem, if there is no urgent request for cooling simulation.
  • Continue working on the RF system optimization paper.


Kirsten Dietrich:

  1. Primarily background reading related to:
    • JLEIC electron cooler design requires magnetized beam
    • Magnetized electron beam, Generation and transport in the cooler
    • LERF
    • Beam dynamics in LERF, related to CSR
    • Proof of principle experiment design to test beam dynamics of cooler beam using LERF
  2. Computer set-up, training

Next two weeks:

  1. Finish background reading, find more relevant articles
  2. Complete Rad Worker I training
  3. Get familiar with using farm to run simulations
  4. Begin to familiarize self with simulations related to magnetized beam (specific) and CSR (general)

Diagonostic Development - K. Jordan
Kevin:

  • My time was split between being evicted from the FEL trailers & LCLS-II CM testing @ LERF
  • There was a review by John Galada & Mark Ross for the feasibility of using the LERF as a cryodule test bed. I presented the logistics. slides are at:

https://www.jlab.org/indico/event/233/

  • Next week is IBIC2017 & Vacaction

Joe:

  • Moving was the big event.
  • Worked on imaging setup for the GTS viewer to image a 4mm x 3mm object
  • Worked on verifying the 2C20 optics
  • Had the VUV turning vessel and the UV collimator removed
  • A little work on the LCLS2 test, mainly with survey

Mike T

  • Trying to recover some rusty analytic skills in understanding Synchrotron Radiation;
  • Supplying Joe Grames with some material for his NSTAR presentation related to positrons at JLAB, and with JPOS17 talks;
  • Mostly helping Yan Wang, Riad, and Mamun understand their attempts at measuring low electron beam emittances.
  • I think I have a hold on the core ideas for a worthwhile pedagogical note concerning Thomas precession and its relationship to the S.R. spectrum. It's been 90 years since Thomas identified this precession. *We may not yet really understand what it means.
  • I'm giving our injector staff what I believe to be some useful perspective on (1) what it means to measure something, and (2) how important it is to keep in mind the limitations of the equipment and the domain of validity of both the analytical techniques and the equipment.
  • They ran into two resolution limits in viewer-based emittance measurement, first for the camera, and second for the YAG screen(!). They had also not yet understood certain subtleties in their data analysis concerning which measurements constrained which physical parameters. They were trying to apply various published measurement procedures without understanding why their attempts had fallen short of clarity. I think everyone has had some benefit from the time spent.
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