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C omplex performance post LHC Injectors Upgrade (LIU)

C omplex performance post LHC Injectors Upgrade (LIU). Eirini Koukovini-Platia Special thanks to: H .  Bartosik and G. Rumolo

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C omplex performance post LHC Injectors Upgrade (LIU)

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  1. Complex performance post LHC Injectors Upgrade (LIU) Eirini Koukovini-Platia Special thanks to: H. Bartosik and G. Rumolo With the inputs of: M. Calviani, C. Carli, R. Catherall, T. Eriksson, A. Fabich, L. Gatignon, S. Gilardoni, G. P. Di Giovanni, M. Giovannozzi, E. Gschwendtner, F. J. Harden, A. Huschauer, M. Lamont, B. Mikulec, R. Steerenberg CERN, Physics Beyond Colliders Annual Workshop, 21-22 November 2017 https://indico.cern.ch/event/644287/

  2. Outline of the talk CERN’s accelerator complex • Overview of the accelerator complex • Brief introduction to the LHC Injectors Upgrade (LIU) • Main baseline items for upgrade in the complex Performance improvement after LIU for non-LHC beams • Talk will focus on users that expect more intensity/better beam quality after LIU • Other users that could benefit from LIU Ongoing activities to ensure the desired performance for the non-LHC beams • Space charge measurements and simulations in the PSB (for BDF and ISOLDE) • Simulations of PS instability at transition crossing • High intensity MTE beams in the PS and SPS (for North Area and BDF) Final remarks

  3. CERN accelerator complex Non-LHC beams LS4 LS5

  4. LIU project Targets to • increase intensity/brightness in the injectors for LHC beams to match HL-LHC requirements • increase injector reliability and lifetime to cover HL-LHC era (until ~2035) Main upgrades in PSB: • H-charge exchange injection at 160 MeV from Linac4 (double brightness out of PSB) • Ebeam increase from 1.4 GeV to 2 GeV (new RF system and main power supply) Main upgrades in PS: • Injection at 2 GeV for protons (higher brightness for same space charge) • Installed and upgraded longitudinal feedbacks (impedance reduction and against CBI) Main upgrades in SPS: • Upgrade of the main 200 MHz RF system (higher intensity) • Electron cloud mitigation and longitudinal impedance reduction (higher intensity) • New LSS5 beam dump, upgraded protection devices (to cope with higher intensity)

  5. Non-LHC beams • For the non-LHC beams, the policy is to ensure that the LIU upgrade would preserve the present complex performance in terms of beam intensity and quality • But apart from the apparent benefit for LHC beams, would there be a positive impact for non-LHC beams? • Can this be quantified?

  6. PSB & ISOLDE LS4 LS5

  7. ISOLDE • Protons to ISOLDE - present: • 0.8 x 1013p+ per ring per pulse with 30%-40% dedicated PSB cycles • Proton beam intensity is limited to 2 μΑ, set by the RP. This limit may be raised for a specific period of time. • Protons to ISOLDE - after LS2: • Beam energy remains at 1.4 GeV (no upgrade in transfer line, maybe during LS3) • Operational scenarios • 50% of PSB cycles to ISOLDE with 0.8 x 1013p+per pulse per ring (2.1 μA) • 30% of PSB cycles to ISOLDE with 1.6 x 1013p+ per pulse per ring (2.56 μA)  Needs approval from RP to raise the intensity limit and to define the time period

  8. ISOLDE: studies done so far Future beam to ISOLDE after LIU assuming • 40 mA from Linac4 • Injection over 100 turns (at least 400 μs flat top for the distributor) • Transverse and longitudinal painting schemes at injection • Negligible losses and blow up along the cycle End of injection process 1.6 x 1013 p per pulse and per ring assuming εN,x = 13 μm J. Abelleira et al, in LIU-PSB Injection meetings

  9. ISOLDE: future studies • Horizontal emittance considered should be 9 μmdue to aperture limitations r.m.s norm. emitt. hor. = 13 μm BSW4 BSW3 injected beam H- BSW2 H- Dump Stripping foil BSW1 H0 Stripping foil x [ mm ] Negative KSW bump Circulating beam Beam hits the vacuum chamber s [ m ] C. Bracco et al, in LIU day

  10. ISOLDE: future studies r.m.s norm. emitt. hor. = 9 μm BSW4 BSW3 injected beam H- BSW2 H- Dump Stripping foil BSW1 H0 Stripping foil x [ mm ] Negative KSW bump Circulating beam s [ m ] C. Bracco et al, in LIU day

  11. ISOLDE: future studies • Studies need to be done to assess the expected proton intensity delivery to ISOLDE considering 9 μm horizontal emittance • Study space charge along the cycle (another potential intensity-limiting factor) • Will the transverse feedback still be able to damp the horizontal instabilities along the cycle for the higher intensity beams? • If transverse feedback is inactive ~ two thirds of the beam is lost Beam loss Beam centroid growth M. McAteer et al, THPRO082, IPAC14

  12. PS & users LS4 LS5

  13. nTOF Protons to nTOF - after LS2: • Target exchange during LS2. Expected lifetime ~10 y • Specifications of new lead target: 1.5 x 1013 p+per pulse • Experiments are interested in increasing intensity towards 1013p+ per pulse • A 20% increase in intensity is desired after LS2 Intensity limiting factors in the PS • Fast transverse instability at transition crossing • For users that need short bunches on target: • RF power for bunch rotation before extraction • Losses at extraction septum (due to the large dp/p) • Protons to nTOF - present: • 6 -7 x 1012 p+ per pulse (PS can deliver ~8.3 x 1012 p+ per pulse)

  14. nTOF: studies done so far Fast transverse instability at transition crossing: • In the PS, the beam is crossing transition energy • Many studies have been done using a single bunch, without γ-jump and with zero chromaticity (after transition crossing) • With increasing beam intensity, a fast vertical instability is observed near transition energy causing beam loss and limiting the beam intensity Beam loss M. Migliorati et al.

  15. nTOF: studies ongoing Measurements with 1.4 x 1012 particles and εL = 2.25 eVs M. Migliorati et al. fr ~ 0.6 - 0.7 GHz Rise time of 0.15 ms PyHEADTAIL simulations with 1.4 x 1012 particles and εL = 2.25 eVs Rise time of 0.12 - 0.13 ms fr ~ 0.6 - 0.7 GHz

  16. nTOF: future studies Beam after LS2 and LIU upgrades • Might increase instability threshold by removing obsolete Continuous Transfer (CT) equipment • build the PS impedance model after LS2 (for example without the CT equipment) and check the impact on the instability threshold prediction with PyHEADTAIL • can anything be done to improve the impedance of the main accelerator component(s) driving the instability? • With Linac4 and injection at 2 GeV, lower εx, y will become available reduction of losses at extraction

  17. SPS & users LS4 LS5

  18. AWAKE Protons to AWAKE - present: • Bright, intense, short, single buncheswith 3 - 3.5 x 1011p+/pulse, 12 cm bunch length, 7.2 s cycle. Protons to AWAKE - after LS2: LIU improvements expected to enhance the beam quality from Run 2 onwards • RF power upgrade and longitudinal impedance reduction will have an effect on beam stabilityand the efficiency of bunch shortening  6 cm bunch length? • Lower transverse emittances from Linac4 and 2 GeV 1 μm?

  19. AWAKE: future studies Need to study the future of LHCINDIV-type beams • Beam production in PSB • Transfer through PS • Space charge at injection • Instability at transition encountered presently above 4 x 1011 p+/bunch • Space charge in SPS

  20. North Area (NA) Protons to NA - present: • ~3.5 x 1013 p+/spill fulfill the needs of the present experiments Protons to NA - after LS2: • Maximum 4 x 1013 p+/spill assumed for future operation (for spill of ~9 s, needs to be lower for shorter spill) Such intensities were already achieved in the past using the CT extraction: H. Bartosik, SHiPcollaboration meeting, June 2016

  21. Beam Dump Facility (BDF) • 4 x 1013 p+/spill assumed with a slow extraction on third integer over 1 s (maybe longer if peak rate of extracted protons not compatible with safe operation of septa) – intensity assumption based on past CNGS operation • Studies ongoing for future beam production in the PSB, low vertical emittance, high intensity MTE, improvement of losses in SPS (LSS2) BDF

  22. Optimization of MTE efficiency NA and BDF: studies ongoing A. Huschauer et al., PRAB, 20, 061001 (2017)

  23. High intensity MTE beam in SPS NA and BDF: studies ongoing • 4 x 1013 p+/spillis the desired • intensity for NA & BDF • (Translates into 2.2 x 1013p+ per inj. • with 92% transmission in SPS) Sum of 2 cycles sent to SPS, measured at PS extraction (A. Huschauer, M. Giovannozzi, F. Tecker) 2nd inj. 1st inj. Intensity along the SPS cycle before dumping the beam during the high intensity test (A. Huschauer, M. Giovannozzi, F. Tecker) Transition crossing Acceleration

  24. Final remarks Non-LHC beams • Some experiments would benefit from higher intensity/brightness beams that will be available thanks to the LIU • ISOLDE could accept ~1.6 x 1013 p+per ring after LS2 • Full extent of intensity reach to be further verified • Space charge measurements and simulations for the PSB ongoing • Higher intensity for other non-LHC users is foreseen, but known intensity limitations need to be assessed in further detail • nTOF: could profit from higher intensity. Studies on the instability at transition ongoing • AWAKE: need to study the future of (high intensity) LHCINDIV-type beams • NA & BDF: require higher beam intensity than in present operation. Studies ongoing to ensure the successful production of higher intensity beams • Focus of this talk has been on existing users • Do we need further studies for future users?

  25. Thank you for your attention!

  26. Back up slides

  27. LIU timeline and milestones • Activities untilLS2 • Beam studies to further test performance, evaluate risks and study mitigations • Final design, procurement and test of hardware (e.g. protection devices, cables, power converters, amplifiers) • Anticipated installation/cabling work during YETS • Work on surface (e.g. civil engineering, racks), Linac4 Reliability Run & commissioning to desired performance • Main LIU installations and hardware work duringLS2 • Beam commissioning of LIU beams after LS2 • Ion beams to be ready for 2021 LHC ion run • Proton beams during Run 3 to be ready for LHC physics after LS3 Run 2 Run 2 LS 2 LS 2 Run 4 Courtesy G. Rumolo

  28. AD, ELENA Protons to AD/ELENA: present and future • Due to the AD deceleration cycle and stochastic cooling, AD takes beam every ~100 s • The intensity of the AD beam (~1.4 x 1013 pot/pulse) mainly limited by shielding in the AD ring and RF capture proton efficiency, but also by transient beam loading in the PS • Similar AD beam request post-LS2 (2-4 x 1018 pot/year) • New lead target specifications of max. 2 x 1013pot/pulse, • ELENA has the same beam specifications as AD • New AD cooler after LS2  faster cooling ~90s

  29. PS impedance model vs. PyHEADTAIL *Measured data from PRAB, 19, 041001 (2016)

  30. East Area Protons to East Area: present and future • Maximum repetition rate of East cycles is 2.5 s, limited by rms power of extraction septum (SMH57)  currently running with 5 cycles per ~30 s supercycle • The intensity of the EA beams is in the range of 1 – 5 x 1011 p/spill • No change expected in the East beam request in the future, except request could be enlarged to ions (at the expense of the proton flux)  ~1018 pot/year

  31. HiRadMat • Beams up to full LHC pulses of 288 bunches with 1.2 x 1011 p+/b are shot to HiRadMat • Require 1.7 x 1011p+/b minimum intensityand2.3 x 1011 p+/b optimum intensity after LS2 • Same cycles as today • ~Double intensity is desired post-LIU • According to LIU commissioning schedule in 2024 this beam will be available

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