# 2017-09-01

From Administrative

**Accelerator Physics (T. Satogata)**

No report.

**Accelerator R and D (Y. Zhang)**

Fanglei Lin

- Continued study of the chromaticity compensation and dynamic aperture in the electron collider ring.
- Discussed JLEIC positron parameters with colleagues and prepared the presentation for JPoS17.
- Miscellaneous: attended JLEIC weekly R&D meetings, attended discussion of test CEBAF pulsed mode for JLEIC.

Vasiliy Morozov

- Geometry-tagging LDRD: generating cross-section tables, generating events, analyzing the data.
- JLEIC R&D planning: reviewing R&D activities, preparing for and participating in a conference call with DoE.
- Ion polarization: teleconference with Anatoliy's group about crab crossing effect and its simulation.
- Lower level activities: detector integration, muon cooling, getting started with River on crab crossing work.

Amy Sy

- Application of inverse flat beam transform to low and high energy beam distributions at the entrance and exit of the bent solenoid section. The unrotated inverse FBT recovers the flat beam but swaps the x-x' to y-y' phase space, and vice versa. For both low and high energy beams, there is significant growth in the vertical emittance - the vertical emittance is very small due to the nature of the flat beam, and the growth may still allow for full acceptance into the ERL. The growth of the momentum spread due to space charge effects is likely more challenging - working on lengthening the initial distribution to see how long the 3.2 nC bunch needs to be to avoid 10x growth in the momentum spread through the merger.
- Using tracking data to recover dispersion functions through one period of the Skew PIC channel to allow for alignment of the parametric-resonance-inducing quadrupoles with the angle between dispersion vectors. Nonzero dispersion at the locations where RF kicks are applied to the beam are destroying the development of the parametric resonance, so different methods are applied to recover the characteristic hyperbolic behavior.
- Checked in with Zack Conway of ANL on ion source/SBIR progress. ANL is working with Muons, Inc. to submit an SBIR proposal on the polarized H-/D- atomic beam source. A collaborative effort has been established with BNL for this proposal, and the Phase I proposal is predicated on a Phase II proposal where a BNL polarimeter is modified to test the device that comes out of simulation work in Phase I.

Yuhong Zhang

- Attended bunched beam cooling meeting and discussed with Haipeng/Shaoheng on data analyses
- Discussed with Jiquan on lead ion beam formation scheme and checked space charge limit at various locations
- Discussed with Fanglei and Jiquan on polarized positron source for JLEIC, assisted Fanglei in preparation of JPOS2017 talk slides
- Updated staged electron cooling scheme and ensured design consistence with beam formation, discussed with He Zhang and Jiquan Guo
- Prepared talk slides for the AAC review
- Started preparation of talk slides for COOL17
- Continued to work with BNL for organizing the EIC Accelerator Collaboration Meeting.

**Computational Physics (Y. Roblin)**

Yves Roblin:

Last week: vacation
Prior:

- preparing for JPOS
- running beam-beam simulations with GHOST and BB3D
- meeting with Rui and Kirsten for planning upcoming work

Next two weeks:

- preparing/attending JPOS
- beam-beam investigation+ preparing for collaboration meeting
- Reviewing start-up readiness for CEBAF (status of optics models, etc..)

He Zhang:

- IBS effect for the lead ion during injection to the collider ring - Simulated how the Pb ion beam expanse under the IBS effect during one hour at the injection energy inside the ion collider ring. The simulation shows very large IBS rate and a significant increase of the emittance. I have discussed the results with Yuhong and Jiquan. Under the current injection scheme, such a large increase of emittance is not acceptable. But Jiquan will look for shorter injection time. With shorter injection time, the increase of emittance will be smaller. As long as the emittance is within the aperture, we can reduce the emittance to the desired value after injection due to the even stronger cooling for heavy ions.
- Turn-by-turn tracking for IMP experiment - An RF model has been added into the simulation code. The ion will obtain a change of momentum with respect to its phase and the RF voltage. I have used the model to simulate the capture progress for the ions with and without cooling.
- Model of the electron beam space charge in cooling simulation - As discussed with Dr. Lijun Mao and Dr. He Zhao at IMP, the space charge effect of the cooling electron beam may play a role in the experiments. I want to add a model of space charge into our cooling simulation code. I am reading papers on this topic.
- Investigation on the painting process simulation in BETACOOL - Read the manual of BETACOOL to figure out the “painting” simulation. However, it is not what we are looking for, the “painting” of ions during the injection. It is the “painting” of electrons during cooling.
- Taylor model based Fast Multipole Method - My PhD adviser, Prof. Martin Berz, at Michigan State University contacted me to write a new paper for the coming Taylor Model Workshop, for which we plan to extend our differential algebra (DA) based fast multipole method (FMM) to Taylor model (TM) based FMM. TM is a intrinsic data type in COSY 9.0. Similarly with DA, TM calculates the Taylor series for a given function at a given point. Besides that, TM also calculates a rigid error bounds for the series. So the extended FMM will not only calculate the potential and the field on the particles, it will also give the error bound of the calculation. I read about TM and wrote some test codes to refresh my mind on the topic. Now it seems straightforward to revise the DA based FMM code.
- Dust particle transfer - Discussed with Rongli about how to proceed this work. We decided to model and simulate dust particles with different parameters and check how long they can travel, in order to find the driving force of this process.
- Other - Reviewed one paper for Numerical Algorithm, one for Journal on Computational Physics, one for Journal on Image and Video Processing, six for International Journal on Computing Science and Mathematics. Totally nine paper reviewed.

Next two weeks work plan:

- Continue developing the turn-by-turn tracking for IMP experiment
- Continue working on the dust particle transfer problem
- Continue developing the space charge model for cooling

Kirsten Deitrick:

Last two weeks:

- Reading:
- Magnetized gun
- CSR and LSC induced MBI
- ERLs in general and mergers in detail
- JLEIC
- Emittance of a magnetized beam

- Meetings:
- visit to GTS, set up meeting with people doing simulations (Sep. 5)
- Cooler meeting
- JLEIC meetings

- Training:
- RW I, including dosimeter
- ODH

- Computer:
- setup desktop programs
- ops account

- USPAS:
- application submitted for Simulation of Beam and Plasma Systems course

Next two weeks:

- Meetings:
- GTS simulations (this morning at 9)
- Alicia re: GPT
- JLEIC/Cooler
- need to set up meeting with Rui, Bob re: impedance calculation/simulation

- Training:
- Ap Com course (a few hours on the 12th)

- Simulations:
- Calculation of thermal emittance from distribution of magnetized beam
- GTS?
- Merger options (including collective effects)
- Simulation on network nodes, not desktop

- Reading:
- CSR and LSC-induced MBI
- filling in gaps, as necessary

**Diagnostic Development (K. Jordan)**

No report.

**LERF (S. Benson)**

August 21 - September 1

- On vacation August 21-25
- Go over frequency choices for Cooler ring gun, injector, and ERL
- Get Kirsten Dietrich started on LERF experiment design
- Completed preparations for Neil symposium
- Help set up safety documents for User Lab 6 experiment
- Assisted Kris Burrows in starting audit of dual use technology items
- Registered for EIC Collaboration meeting

September 5-15

- Prepare talks for JPos17, COOL17, and EIC collaboration meeting
- Attend JPos16 and organize LERF tour