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SC-13 – Consequences for us?

SC-13 – Consequences for us?. Overview of the SC-13 Workshop Some Highlights Main Outcome Questions and Responses Our Week with the Code Experts. 1. SC-13 Workshop Organization . The scientific program by IAC: Y.Alexahin (FNAL), O. Boine‐Frankenheim (TUD/GSI),

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SC-13 – Consequences for us?

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  1. SC-13 – Consequences for us? • Overview of the SC-13 Workshop • Some Highlights • Main Outcome • Questions and Responses • Our Week with the Code Experts Outcome of SC-13 1

  2. SC-13 Workshop Organization The scientific program by IAC: Y.Alexahin (FNAL), O. Boine‐Frankenheim(TUD/GSI), Hofmann (GSI/HI-Jena), J. Holmes (SNS), S. Machida (RAL), E. Metral (CERN), K. Ohmi (KEK), J. Qiang (LBL), F. Zimmermann (CERN) Approved/Sponsored: ICFA, EUCARD, ACCNET, HIC4FAIR, LIU The program, the presentations and session and workshop summaries are available at the indico page: https://indico.cern.ch/conferenceDisplay.py?confId=221441 Outcome of SC-13 2 2

  3. SC-13 Workshop Participants There have been 82 registrants distributed over the following countries, laboratories and companies: Switzerland (CERN) ------------------------------------------------------------------ 38 Germany(GSI, Frankfurt University) ------------------------------------------- 13 UK(STFC) ------------------------------------------------------------------------------- 12 USA(Fermilab, SNS, LANL, LBNL, MIT, Tech-X Cor., Muon Inc.) ---- 11 Japan(KEK) ---------------------------------------------------------------------------- 2 Austria(MedAustron) --------------------------------------------------------------- 1 China (IHEP) ---------------------------------------------------------------------------- 1 France(Saclay) ------------------------------------------------------------------------ 1 Mexico(universidad de sonora) ------------------------------------------------- 1 Russia(ITEP) --------------------------------------------------------------------------- 1 Sweden(ESS) -------------------------------------------------------------------------- 1 Outcome of SC-13 3

  4. SC-13 The Group Photo Outcome of SC-13

  5. SC-13 Workshop Sessions The workshop lasted for 3 and half days and the program has been grouped in the following sessions: 16th of April Stimulus/Project Modeling/Theory/Overview • Schmidt, Bartosik Space Charge StudiesOhmi, Huschauer • Discussion Hofmann, Fitterer 17th of April • Machine model (Theory and Instruments) Prior, Forte • Code development Alexahin, Wagner • Discussion Holmes, Aumon • 18th of April • High intensity effects Machida, Noll • Synergies Zimmermann, Hein • Discussion Metral, Wasef • 19th of April • Mitigation and advanced techniques • Boine-Frankenheim, Hernalsteens • Joint Discussion/Outlook Hofmann, Holmes, Metral,Bartosik, Rijoff Outcome of SC-13 5

  6. Why this SC-13 Workshop? General CERN Interest • The LIU goal: “Double the number of particles per bunch” • ➔ Space Charge has become very relevant for LHC injectors • Generational Problem for the Injectors ➔ We have started to create a new team of expertise on space charge covering all 3 rings • Strengthen Collaboration with other Laboratories (resurrected or new): • GSI • KEK • Fermilab/SNS • Others? • We are at a crossroad for our LIU studies: • Huge effort made to do experiments until this spring • ➔ This workshop • Simulations to understand and improve our machines to reach LIU goal Outcome of SC-13

  7. Some Hightlights This can only be a small sample with emphasis and direct relevance in view of LIU Apologies for having to leave out lots of relevant material! Looking for catchy statements that reflect what the space charge community is presently thinking… Outcome of SC-13

  8. Chris Prior SpaceChargeModel Outcome of SC-13

  9. Chris Prior SpaceChargeModel Outcome of SC-13

  10. Measurements: half integer resonance crossing… (static w. point above 2Qy=9) Transverse emittances constant @ C450 (switching off QNO correctors) Vincenzo PSB Nice case for code benchmarking (simulations are on-going) Outcome of SC-13 Status of the space charge studies and measurements in the CERN PSB Vincenzo Forte – Space charge workshop – CERN - 16/04/2012

  11. Wasef PS III. 4thorder Resonance • Raymond WASEF, Space Charge Workshop, 16/04/13, CERN  The 4th order resonance seems to be excited by space charge 8

  12. Huschauer PS Compensation of resonances before after vertical tune constant Compensation of 2qx+qy=1 3qy=1 is clearly enhanced horizontal tune constant

  13. Huschauer PS Compensation of resonances before after vertical tune constant Compensation of 3qy=1 additionally: reduction of 2qx+qy=1 horizontal tune constant

  14. Outcome of SC-13

  15. Outcome of SC-13

  16. Outcome of SC-13

  17. Bartosik SPS Outcome of SC-13

  18. KapinFermilab Slow extraction in Debuncher using Orbit • 3-order resonance with variable tune Qx and sext. str. K2 • First “strange” results for extraction: “intensity drop” intensity vs turns • “Intensity drop” was resolved simply at the beginning: Valery advised to make mesh refinements • PIC: “Total Beam size increases at slow extraction => mesh number should be increased to keep the cell size” Outcome of SC-13

  19. Simulations with ORBIT by V. Nagaslaev KapinFermilab Ramps are given in tables; Npart in bunch ~ 2.5e12 Outcome of SC-13

  20. N_macro_surv vs Turn Number for the Debuncher • Timing on CERN computer • Macro version ~20-24h • MADX-SC • ~2-4h MAD-X V3 with Macros MADX-SC V5 Outcome of SC-13

  21. Urschütz Driving terms (PSB) 3Qy=16 – uncorrected Phase and amplitude data obtained from Fourier spectra Beam intensity Vertical beam position Normalised phase space resonance strength and phase: Fourier spectrum Outcome of SC-13

  22. Urschütz Driving terms (PSB) 3Qy=16 – compensated Beam intensity Vertical beam position Normalised phase space Results from the measurements: |h0030| = 9.0±0.6*10-3 mm-1/2 ψ0030 = -21º±14º Calculated compensation currents (for two independent skew sextupoles): IXSK2L4 = -29.3 A, IXSK9L1 = +15.3 A Fourier spectrum Outcome of SC-13

  23. Machida PIC Outcome of SC-13

  24. Machida PIC Outcome of SC-13

  25. Machida PIC Outcome of SC-13

  26. Machida PIC Outcome of SC-13

  27. Ohmi J-PARC MR Outcome of SC-13

  28. Ohmi J-PARC MR Outcome of SC-13

  29. Holmes pyORBIT Outcome of SC-13

  30. Some History Recent findings, when using ORBIT: Frank Schmidt, et al. Micro-scale effects APC Seminar at Fermilab, November 2012 “Benchmarking of PTC_ORBIT & SYNERGIA ”, https://indico.fnal.gov/conferenceDisplay.py?confId=6115 Micro-scale unphysical effects: H-detuning (left), fake tune evolutions, artificial dipole oscillations,…May jeopardize the validity of beam modeling Without SC – NO Micro-scale unphysical effects. WANTED: Consistency between ~Exact Trackers and Approximate SC Solvers Search for remedies Outcome of SC-13

  31. 3.A Hybrid Solvers, SC Templates Library of Templates Pre-Assigned densities Ring Disc Template • General  • Halo • Hollow Beam Private Communications: A. Friedman, D. Grote, I. Hofmann, M. Reiser, J. Struckmeier and R. York Outcome of SC-13

  32. Outcome of SC-13

  33. Outcome of SC-13

  34. Outcome of SC-13

  35. Outcome of SC-13

  36. Nghiem Outcome of SC-13

  37. Hofmann GSI Outcome of SC-13

  38. SC-13 Main Outcome I 1) The workshop has shown a rich activity on space charge related topics at CERN (LIU), GSI (FAIR), and RAL (ISIS upgrade).Several studies have been presented on experimental work and in particular concerning the LIU studies and ISIS upgrade. 2) In the session of code developments, the issue of code benchmarking has found a lot of attention with regards to long-term tracking. The presentation of the status of code benchmarking has been discussed and the issue about the noise created by PIC codes has evoked intense discussions. This topic has raised broader interest, in particular by J. Amudson, Eric Stern, J. Holmes, JiQiang, and Jean-Luc Vay. The decision has been taken to use the GSI test suite for benchmarking of frozen space charge models also for the benchmarking of PIC codes, both 2.5D and 3D. Firm plans have been made to benchmark Synergia and Orbit and hopefully also IMPACT and WARP. Outcome of SC-13 38

  39. SC-13 Main Outcome II • 3) Some discussion has focused on role of GPU in the high intensity beam dynamics. Effort reported by GSI, RAL, FNAL were discussed at a deep technical level, and the present difficulties were highlighted. • 4) Interesting from a theoretical standpoint has been a discussion about possibly equating PIC noise with intrabeam-scattering. To this end, previous work by J. Struckmeierhas been reviewed on the effect of PIC noise on emittance growth. The audience has expressed the interest to study this topic in some detail. Outcome of SC-13 39

  40. Question & Responses • During the Joint Discussion Session 7 Question have been presented to the community. These questions have been formulated beforehand both at CERN & GSI • I have modified them for this talk • The full set can be found on the web: ➔http://indico.cern.ch/internalPage.py?pageId=9&confId=221441 Outcome of SC-13

  41. Question 1 • Responses: • What we really need is a better description of the machines • Our simulations codes are more or less fine ➔ benchmarking! • The question is how we can improve the nonlinear description of our machines? What are the possible methods? • Modeling of linear and nonlinear chromaticity • Resonance driving terms (correct chromaticity, kick in both planes, ) • some data in PS, PSB: difficult since only 1 family of sextupoles • Experience at other labs: • Chromaticity, DTA • ISIS: turn-by-turn • Octupolarcomponents by local bumps • There has been a significant amount of work being done for the PS in particular. But we still need a reliable magnet by magnet model which would require a more structured effort. • 1) What about the modelling of our machines? Outcome of SC-13 41

  42. Question 2 • Responses: • There seems to be consensus that resonances due to non-linear fields in conjunction with the tune spread due to space charge seems to lead to both problems: just approaching a resonance leads to emittance blow-up and resonance crossings may lead to losses. • On a deeper level the community is split about the questions if these incoherent or also coherent effects are important, as being discussed concerning the half integer resonance crossing in the PSB. • 2) What are the relevant mechanisms for beam loss and emittance growth? Outcome of SC-13 42

  43. Question 3 • Responses: • Concerning instrumentation there has mainly been proposals to provide 1000 turn BPM systems with good resolution • Further the developments concerning wire scanners to allow for instance a better resolution of beam halo, i.e. improving existing instrumentation. • Transverse tomography and collimators to reconstruct the transverse profile have been proposed as possible new tools. • It was also mentioned that kickers in both planes are important to study coupled resonances. • There has been a proposal to study coherent effects: A quadrupolar pickup should allow to measure coherent response of the beam to the half integer resonance. In fact, this pickup would allow for the first time the measurement of the real space charge tune spreads in a machine. • 3) Which instrumentation do we need to measure our space charge effects? Outcome of SC-13 43

  44. Question 4 • Responses: • This issue has been central in the discussion during the workshop. • On the one hand, benchmarking of several PIC codes have now been pursued and compared with the results of frozen space charge codes. • ➔This effort will take the better part of this year! • On the other hand, renewed interest has been expressed to look into the noise issue of PIC codes in long-term storage ring simulations in more detail by several teams. • It has been mentioned by PIC code developers that the single particle behavior allows a lot of in-sight into the understanding the working of the PICcodes. • 4) PIC versus Frozen model: Which difference is "normal" and which is not? Outcome of SC-13 44

  45. Question 5-7 • Responses 5) No clear position from the audience except that the experimental data would have to be well documented to allow for a clarification. • Responses 6-7) Both of the last 2 questions simply would need more studies. In fact, our simulation tools have to be better understood and benchmarked with experiments before a reliable answer can be given. • 5) There seem to be some beams in the PS with most of the beam in the PS below the integer resonance ➔not too many losses nor emittance growth. • Can we explain this? • 6) What is the maximum allowed space charge tune shift? • 7) What can we do from the optics point of view to reduce space charge effects? Outcome of SC-13 45

  46. Code Developer Meeting 22-26.04.13 • Invitation of code developersafterSC-13 workshop • Jeff Holmes(SNS) ORBIT proper • Leonid VorobievORBIT expert of Fermilab • Eric Stern for Synergia • GiulianoFranchettistayed on for a few days • Main goals • Learn from the experts about the 2 PIC codes • Demonstrate issues we had with un-physical behavior • Plan benchmarking effort for both codes • Mitigation efforts for the noise problem • Alternative approaches • Lively discussions and presentations all week long Outcome of SC-13 46

  47. Code Developer Meeting II • The support for the ORBIT code as we know it will be discontinued this year! • It will be replaced by pyORBIT • Mainly replacing Interface • Hopefully they will introduce a hook to PTC • There might even be a manual! • Jeff gave a lecture about the most relevantORBIT modules • Benchmarking is agreed to proceed Outcome of SC-13 47

  48. Code Developer Meeting III • Eric explained MPI as used in Synergia and gave a detailed report on the RUN facilities in their code. • Jeff raised the question if PIC codes are the proper tool for long-term studies in storage rings! He expressed hope that the so-called FMM technique might be the right approach for the future. • Leonid explained in detail both his mitigation proposal for minimizing the noise in ORBIT and his space charge templates as a possible long-term solution. • Summary: http://frs.web.cern.ch/frs/Source/space_charge/SC-13/Code_developer_meeting_22-26.04.13/ Outcome of SC-13 48

  49. Reserve Outcome of SC-13 49

  50. Outcome of SC-13

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