Director - M. Spata
No report. Acting Accelerator Division Head
Accelerator Physics - T. Satogata
Previous two weeks (Apr 2-Apr 13) - ADMIN: Eric Thompson thesis input, diss defense (Apr 12, CNU) - ADMIN: Leadership/group meetings, AWP updates - IPAC18: Scientific secretariat work (student program, light peer review) - JLEIC: Followup collaboration meet input, pCDR outline/infrastructure, lunches - JLEIC: ion dump info to Vasiliy - ODU: Continue teaching PHYS 417/517 Tue/Thu, Randy advising - OPS: Hall D TAC runs support, CEBAF reference ops plan input - OPS: Hall D beam convergence iterations - OPS: Plan OOC, Beam Studies (Tuesdays), BTeam, optics support/tuning meetings Next two weeks (Apr 16-Apr 27) - ADMIN: Eric Thompson final thesis revision input - ADMIN: Leadership/group meetings, staffing input - IPAC18: Travel, editing, conference secretariat (Apr 25-May 5) - JLEIC: Followup collaboration meet input, pCDR outline/infrastructure, lunches - ODU: Finish teaching PHYS 417/517 Tue/Thu, Continue Randy advising - OPS: Hall D TAC runs support, CEBAF reference ops plan input
Previous two weeks (Apr 2-Apr 13) - IPAC18: Light peer review organization - PERLE: Lattice to Yves for conversion to elegant, IPAC paper - LHeC: Parametric studies - ADMIN: REU student assignments Next two weeks (Apr 16-Apr 27) - IPAC18: Light peer review organization - IPAC18: Poster and paper preparation (PERLE) - OPS: Arc2 optics refinement
Previous two weeks (Apr 2-Apr 13) - JLEIC: Work more on the ion effect in the JLEIC e-ring - JLEIC: Give the presentation on ion effect in the JLEIC e-ring at Apr 12 R&D meeting - IPAC18 Plan and start writing JLEIC Collective Effects paper - VACATION: Apr 13 Next two weeks (Apr 16-Apr 27) - VACATION: Apr 16 - IPAC18: Finish JLEIC Collective Effects Paper - IPAC18: Plan and start writing JLEIC Coupled Bunch Instability paper - IPAC18: Prepare posters before travel
Previous two weeks (Apr 2-Apr 13) - JLEIC: Evaluate possibilities for increasing Booster size - JLEIC: Begin work on retuning, including octupoles to manage significant amplitude-dependent-detuning seen - IPAC18: Plan and start writing Booster design paper Next two weeks (Apr 16-Apr 27) - JLEIC: Continue DESIREE LDRD preparation, budgeting - IPAC18: Finish Booster design paper, poster - JLEIC: Research and add octupoles to booster
Previous two weeks (Apr 2-Apr 13) - IPAC18: Finish paper and poster, write text for PERLE paper - JLEIC: trying to get beam through 11 turns of the CCR: added faux RF cavity to add energy lost to CSR, fix chirp imposed by CSR wake, added fake collimator to remove head/tail particles that go to high energy - JLEIC: thinking through pre-CDR outline and work to be done Next two weeks (Apr 16-Apr 27) - PERLE: evaluate mBI gain for 3 passes up (Vlasov-solver) - PERLE: push a distribution through the system with and without CSR (elegant lattice from Yves/Alex) - JLEIC: deep dive on CCR arcs to try and understand why "simple arc" is so much better at mBI than all the others we've evaluated
Accelerator R & D - Y. Zhang
- Investigated JLEIC collider rings’ geometry and presented in the JLEIC R&D meeting.
- Working on optimizing a new electron ring that fits in the JLab site.
- Continuing single particle nonlinear dynamics study for the electron ring.
- Miscellaneous: provided optics support for the crabbing study in the electron ring, attended discussion on JLEIC alternative layouts, attended CASA group meeting, attended the JLEIC R&D meetings, attended JLEIC general meeting, attended JLEIC detector meeting.
- R&D planning: updating funded FOA project scopes, prioritizing unfunded proposals and discussing them with DoE
- Preparation of IPAC'18 papers and posters: crab crossing with River and polarization with Anatoliy
- Exploring options for collider ring geometries
- Study of a higher-energy JLEIC option
- Preparation of three presentations for DIS'18
- Work on geometry tagging LDRD: teleconference with collaborators and preparation of a mid-year report
- Working on an LDRD proposal for a laser-driven polarized deuteron source for JLEIC. The concept involves a new way to nuclearly-polarize deuterons that are bound in deuterium halide molecules (DCl, DBr, etc.) using a few pulses of IR laser light to excite a rotational state in the molecule. The rotational polarization couples to the nuclear polarizations of the bound atoms through the hyperfine interaction, and the atoms are dissociated with another laser pulse at an appropriate time where the polarization on the deuteron is maximal. The LDRD proposal only covers the neutral polarized atom source as the first stage for a JLEIC polarized ion source - polarized ions could be generated with the proposed source by the resonant charge-exchange ionization method utilized in existing atomic beam polarized ion sources.
- Discussions on the Counter ERL concept, including the possibility of deeper energy recovery by merging/splitting the counter-propagating orbits near the electron gun.
- Working with H. Huang and V. Morozov on crab dynamics paper for presentation at IPAC18.
- Preparing IPAC18 presentation materials on toroidal merger simulations.
- Begin to do error study on electron collider ring. I assumed misalignment, strength error to the magnets in a FODO lattice of electron collider ring. And I add one corrector kicker and one monitor on each side of every quadrupole. I found the lattice is more sensitive compared with the lattice in ion collider ring.
- LDRD study of the geometry tagging after the collision. Mark Baker successfully made the output events of 40k J/psi incoherent decay. After cutting with trueX<0.01, trueQ2<10.0(Q2>1), and with status==1, each event have:1 scattered electron and either an e+e- pair or a mu+mu- pair. After cutting with Nnevap==0, there are 1181 events left to match the figure from the white paper.
- Begin to write the proceeding paper of 'Status of the JLEIC Ion Collider Ring Design' in IPAC'18
- Prepared talk slides for APS conferences
- Worked on IPAC posters
- Worked on various issues on JLEIC and attended many meetings
Computational Physics - Y. Roblin
- Mar. 31 - Apr. 13
- Cornell Straight Merger:
- -have made 3D field map out of truncated 1D field map for coil pair
- -run for straight merger experiment
- -run for extended amplitude
- -prepping 3D field map of fundamental + third for comparison
- -combine parameter sweep results, get nominal operating parameters
- -run CSR+SC+shielding for Chris
- -attempt to fix segmentation fault problem
- -can successfully run PyECLOUD on non-JLab laptop; working to get devl79 install functioning
- -can now run on devl79; beginning to benchmark against Shahid's work (for reference)
- -scheduled next meeting for May 14th at 10
- -put in Linac'18 abstracts (invited talk, Straight Merger, Magnetized injector, eCloud)
- -SL 4/5-4/6, 4/12
- Apr. 14 - Apr. 27
- Magnetized Beam:
- -fix booster in both options
- -fix asymmetries in FEL
- -start scanning for charges/field/spot size
- Cornell/Straight Merger:
- -run for fundamental + third
- -run for fundamental + third using magnetized beam
- -attempt to fix segmentation fault problem
- -beginning to benchmark against Shahid's work
- -run with current parameters
- Mar. 30 - Apr. 13
- -model team. established a list of tasks to do in near future
- -model team : presented to BTEAM, discussion about prioritization.
- -technote writing/data analysis
- -send FOA letter to Manouchehr , setup budget act code .
- -read papers on multivariate polynomial evaluation (in order to use this for fast calculations of higher order maps in BB3D)
- -interview panel for radiation physicist
- -finalized PERLE optics in ELEGANT (all passes + deceleration)
- -manager training.
- Apr. 14 - Apr. 27
- -review /adjust xfer line from CEBAF->Ering
- -prepare for the start of the FOA, plan activities, gather up docs and tools
- -machine support
- -BTEAM coordination (04/17 and 04/24)
- -planning/preparing for beam studies (autosteer, bunch length meas, etc..)
- Mar. 31 - Apr. 13
- JSPEC Development
- -JSPEC GUI starts to obtain outside users.
- -It was reported to us that JSPEC cannot read some MAD-X tfs files provided by Dr. Steck from GSI. I revised the lattice file parser to read these files. A check of the element position is also added to the parser. If the position of one element is the same as that of the previous element, this element will not be saved into the lattice. In this way we avoid redundant elements and redundant calculation for IBS rate. For the tfs file from Dr. Steck, the element number is reduced by 50% after this redundant element check is applied.
- -It is also reported to us that JSPEC generates NaNs in some simulations. I checked the input file and output file and found that the problem is due to very large product of the time step and the expansion rate, due to which the coordinates of some particle go out of the range of the double floating point number. JSPEC code is revised to prevent this from happening. If a coordinate is less than 1e-60, some computations will not be carried out and the coordinate will not be updated. However, to make the simulation valid in physics, it is necessary to make sure the product of the time step and the expansion rate is not too large.
- -I am integrating the turn-by-turn model and the RF model to the JSPEC release. This is needed for IMP data experiment and JSPEC benchmarking with the IMP data. This has not been finished.
- JLEIC Cooling Simulation
- -Simulations were carried out to check what we can achieve without cooling at the cooler for 100 GeV proton beam (44.7 GeV CM energy). I tried to use both round beam and flat beam and assume either the constant proton bunch length with varying momentum spread or both constant proton bunch length and constant vary momentum. The results are summarized in Table 1. If we use a round beam, we see severe reduction of proton beam current without dispersion at the cooler. Using a flat beam helps us, because the charge density increases for a given total charge number and hence the cooling is stronger. For fixed bunch length with varying momentum spread with flat beam cooling, we still see a large reduction of proton current. But if we assume the momentum spread is also constant, there is almost no need to reduce the proton beam current. The flat electron beam provides enough cooling even without dispersion at the cooler. But this means we are able to introduce longitudinal heating to compensate the cooling and maintain the momentum spread.
Table 1. Ion beam current in equilibrium (% of design parameter)
Round beam / Flat beam
Fixed bunch length, varying dp/p 40% / 56%
Fixed bunch length, fixed dp/p 58% / 98%
Diagnostic Development - K. Jordan
- LCLS-II work
- Moved F100 cryomodule to North linac SB
- Moved LCLS-II CM # 5 to LERF vault
- 4 Stands have been mounted, surveyed - grouting next
- Wheel extensions arrived as well as a semi full of additional loaner equipment from SLAC
- Cable list for the first 240 cables has been turned over for cable label pricing then cables can be pulled in
- Met w/ Joe & Radiabeam for high power wires scanner
- More work on rayTrace analytical tools and path in preparation for final segment of Spring 2018 run
- Continuing to draft a requirements document and example implementation sketch for a robust background cavity cresting routine able to use data from any of FFB; BEM,BPMs; or SLM based data streams. A specific goal is low execution time.
- Bunch structure diagnostics using 1A SLM (beam studies and tool development with B. Freeman and others) to support increased beam current to Hall C for their experimental needs.
- Other general support for the (extended) Spring 2018 operational run
- Most of the last two weeks were devoted to designing a new imager for the Lambertson viewer. Due to the small chamber I had to develop a couple of new analytical models as well as attempt to learn how I can use ZEMAX optimization code to perform the same task not using the thin lens approximation. While the imager optics were not difficult attempting to add an inline illuminator was difficult. This required a few iterations before I ended up with a nice design. Other major tasks performed this week were LCLS-II and Radiabeam CRADA work. For LCLS-II it was several meeting including weekly meetings, and design reviews for cable routing, Cryo can and Cryo. I also worked with S&A giving them floor plate anchor locations and with the new installation team on WGs.
LERF - S. Benson