Yuhong Zhang for the JLEIC Collaboration Status of
Yuhong Zhang for the JLEIC Collaboration Status of JLEIC Design • • • Highlights of JLEIC Design Study JLEIC Design and Luminosity Performance Major Subsystems Accelerator R&D Beyond pre. CDR Summary Electron-Ion Collider Accelerator Collaboration Meeting 2019 9 -- 11 October 2019, Argonne National Laboratory
Highlights Since Last Year EIC Collaboration Meeting • The JLEIC baseline now covers CM energy from ~20 Ge. V to ~100 Ge. V, with an upgrade option to 140 Ge. V CM energy Ø Meets/exceed all EIC requirements including CM energy range set forth in the white paper • Revised the ion complex design by including a full-size high energy booster Ø Enabling quick replacement of colliding ion beam high average luminosity Ø A factor of 3 Reduction of ion beam IBS rate after the ion collider ring design optimization • A factor of 2 reduction of the cooling electron beam current (and bunch intensity) in the high energy ERL cooler without compromise of luminosity performance • Started conceptual design of high voltage (4. 3 MV) DC cooler • Eliminated gear change scheme and associated risk of coherent beam-beam instability • Added damping wigglers in the electron collider ring to enhance SR damping at 3 to 6 Ge. V range • Completed two pre-Conceptual design reports (65 Ge. V CM and 100 Ge. V CM) 2
Jefferson Lab Answers EIC Science Call • Large established user community in the field Up to 12 Ge. V @1. 5 GHz • CEBAF is the world highest energy CW SRF linac -As a full energy injector (requiring no upgrade) -Maintains a highly-polarized high-current beam in the electron collider ring using demonstrated top-up injection • New ion injector complex and collider rings -Modern design and technology -No constraints posed by existing infrastructure • Design driven by experimental requirements -Novel high luminosity concept -Luminosity optimized around CM energy range of physics interest -Novel figure-8 design for high polarization of any particles including deuterons -Deeply integrated detector and machine design for full acceptance 3
JLEIC Layout • Electron complex - CEBAF as a full energy injector - Electron collider ring: 3 -12 Ge. V/c High Energy Booster (13 Ge. V/c) Interaction point Ion linac (150 Me. V ) Electron source • Ion complex - Ion source, SRF linac: 150 Me. V for protons - Low Energy Booster: 8. 9 Ge. V/c - High Energy Booster: 13 Ge. V/c - Ion collider ring: 200 Ge. V/c Ion collider ring (200 Ge. V/c) • Up to two detectors • Upgradable to 140 Ge. V CM Interaction point 100 m Low Energy Booster (8. 9 Ge. V/c)Electron collider ring (3 -12 Ge. V/c) 12 Ge. V CEBAF 4
JLEIC High Luminosity: Many Small Short Bunches Conventional hadron colliders - Few colliding bunches low bunch frequency - High bunch intensity long bunch & large β* Strategy: Design a lepton-hadron collider like a lepton-lepton collider JLEIC approach: many small short bunch colliding beams ~ 1/ε or ~1/β* Beam Design • High repetition rate • Low bunch charge • Short bunch length • Small emittance Proved & now standard approach for lepton-lepton colliders (KEK-B reached > 2 x 1034 /cm 2/s) Why JLEIC can adopt this luminosity concept - Based on the existing CEBAF, its beam already up to 1. 5 GHz - New green field ion complex to deliver high bunch repetition rate Bunch freq. (MHz) Bunch intensity (1010) Bunch length (cm) β*y (cm) RHIC 9. 4 16 to 18. 5 60 to 75 ~90 HERA 8. 2 7. 3 16 18 JLEIC 476 1 ~2 1. 2 KEKB 158 - 458 6. 4 – 2. 1 ~0. 6 0. 59 Damping Design • Synch. radiation • Beam cooling IR Design • Small β* • Large attainable beam-beam • Crab crossing Role of cooling of ion beams Critical for emittance reduction & shortening bunch for preserving ion beams in 6 D phase space Assisting injection & accumulation of ions from linac No SR damping for protons/ions in JLEIC energies Electron cooling to provide required strong damping 5
JLEIC High Polarization Enabled by Figure-8 Ring • • • Protons & light ions are injected highly polarized from sources spin design is focused on preserving polarization • • Polarized deuterons in the EIC energy range (~3 Tm vs. < 400 Tm for deuterons at 100 Ge. V) JLEIC adopted a figure-8 topology for all rings Enabled by a green field collider ring and injector complex Spin precessions in the left & right arcs are exactly cancelled spin tune is zero energy independent Additional fields set a small spin tune away from spin resonances in the whole energy range Spin can be controlled and stabilized by compact spin rotators (no need of Siberian Snakes) these spin control element have no effect on orbit beam/dynamics in the entire energy range The electron ring follows the ion ring foot-print, however, figure-8 helps maintain electron polarization under spin flip S B Conventional synchrotron Figure-8 synchrotron S B B • Energy dependent spin precession • Cross spin resonances during acceleration • Siberian Snake may help but still difficult B Spin precessions in left & right are cancelled Spin turn is zero (energy independent) 6
JLEIC Parameters and Luminosity CM energy Ge. V 21. 9 p 40 44. 7 e 3 p 100 e 5 69. 3 89. 4 98 P e 200 10 443/4=119 4. 2 4. 6 0. 75 0. 82 85 80 3. 2 1 1. 5 664 0. 5 133 19. 2 4 2. 3 0. 8 0. 006 0. 024 p e 200 12 443/4=119 4. 2 2. 2 0. 75 0. 39 85 80 3. 2 1 1. 5 1145 0. 5 229 27. 5 4 3. 3 0. 8 0. 003 0. 014 476 0. 59 0. 42 85 2. 5 0. 2 8 1. 3 0. 015 3. 9 2. 75 85 1 18 3. 6 30 9. 8 0. 12 1. 06 0. 75 85 2. 5 0. 65 0. 13 8 1. 3 0. 015 4. 7 3. 35 85 1 83 16. 6 5. 72 0. 93 0. 049 P e 200 6 476/4=119 4. 2 19. 4 0. 75 3. 45 85 85 3. 56 1 2. 89 143 0. 5 28. 6 21 23. 5 1. 6 1. 25 0. 015 0. 12 Beam-beam, x 0. 01 0. 15 0. 0135 0. 044 0. 010 0. 053 0. 004 0. 024 0. 002 0. 014 Laslett tune-shift 0. 055 Small 0. 018 Small 0. 004 Small 0. 0055 Small 0. 0052 Small Beam energy Collision freq Particles/bunch Beam current Polarization Bunch length Norm. emitt, x Norm. emitt, y Horizontal β* Vertical β* Beam-beam, x Ge. V MHz 1010 A % cm µm µm cm cm Hour-glass (HG) 476 0. 85 0. 73 0. 7 0. 66 0. 67 Peak lumi. , w/HG 1033/cm 2 s 2. 9 14. 6 17. 1 4. 2 1. 41 Average lumi. * 1033/cm 2 s 2. 8 14. 0 13. 3 2. 7 1. 07 * Average luminosity was calculated assuming a one or two hour proton beam store without or with high energy bunched beam electron cooling, plus 5 min beam formation time (mainly due to detector overhead). 7
100 Ge. V CM 10 • JLEIC has robust luminosity performance • Performance options mitigate high energy cooling risk Beam-beam dominated e rg a h e c ated c a in Sp om d Series 1 peak luminosity Series 2 average luminosity n ro ot hr ion d nc iat te Sy rad ina m do Peak and Average Luminosity (1233/cm 2/s) JLEIC Luminosity Performance 1 20 40 60 80 100 Upgrade to 140 Ge. V CM • High energy electron cooling of protons up to 150 Ge. V • Average luminosity was calculated assuming • 2 hour beam store with high energy electron cooling • 1 hour beam store without high energy electron cooling • Plus 5 min beam formation time (mainly due to detector overhead) • Complete beam formation cycle is ~30 min, however the most part can be done in parallel, taking advantage of a full size high energy booster Peak Luminosity (1233/cm 2/s) CM Energy (Ge. V) 10 1 20 40 60 80 100 CM Energy (Ge. V) 8 120 140
Ion Complex and Beam Formation • A new facility, no constraints posed by existing infrastructure • Modern design and technology: figure-8, SRF linac, high voltage DC cooling, high energy bunched beam cooling 54 -56 cycles Energy Low energy booster Multi-turn injection & accumulation 150 Me. V high energy booster Stacking & pre-cooling 8 Ge. V DC cooler 4. 3 Me. V Pre bunch splitting 12. 1 Ge. V Energy collider ring bunch splitting, capture 20 Ge. V Emittance preservation Up to 200 Ge. V Bunched beam ERL cooler Up to 110 Me. V proton Low energy booster Multi-turn injection & accumulation 41 Me. V DC cooler 21 ke. V high energy booster Stacking & pre-cooling 4. 3 Ge. V 2. 1 Ge. V DC cooler 2. 3 Me. V DC cooler 1. 1 Me. V collider Ring bunch splitting, capture 20 Ge. V Emittance preservation Up to 78 Ge. V Bunched beam ERL cooler Up to 43 Me. V Lead ion 9
JLEIC Ion Injector: Warm/SRF Linac • • • Capable of accelerating all beams: polarized proton and light ions, unpolarized light to heavy ions Two RFQs & separate LEBT/MEBT due to different emittances & voltage requirements: light ions (A/q≤ 2), heavy ions (A/q≤ 7) RT Structure: IH-DTL with FODO focusing lattice for significantly better beam dynamics SRF section made of 3 QWR and 6 HWR modules Half-Wave Quarter-Wave Stripper section for heavy-ions after 1 st QWR module Resonator (HWR) Resonator (QWR) Pulsed Linac: up to 10 Hz rep rate, ~ 0. 5 ms pulse length 150 Me. V proton 42 Me. V/u Pb cold section Output Beam Parameters End-to-end simulations proton lead ions Parameter Energy Transmission Norm. transverse emittance (90%) Norm. longitudinal emittance (90%) Energy spread (rms) Units Me. V/u % H 131 99. 7 π·mm·mrad 2. 3 1. 3 0. 8 π·ns·ke. V/u 8. 8 7. 1 4. 6 % 0. 13 0. 12 0. 1 10 DPb 62+ 75. 5 44. 5 100% 98. 3
Low and High Energy Boosters Low Energy Booster • 150 Me. V from the ion linac; extraction energy: 8 Ge. V • Circumference 604 m, warm magnets & FODO lattice • γt=10. 6 to avoid transition crossing for all ions γt=10. 6 High Energy Booster • • • In the tunnel along with the two collider rings, cir. 2336 m Accelerates protons from 8 to 12. 1 Ge. V kinetic energy FODO lattice (180º phase advance) with warm magnets The bends at either end of arcs reduced to match the geometry γt = 15. 6 to avoid transition crossing for all ions DC cooler 21 ke. V γt = 15. 6 DC cooler 4. 3 Me. V Detector-bypass • Avoid the detector region in the collider rings, • 6 straight FODO cells and 8 4 meter dipoles for a 5. 03 m excursion over ~46 m beam line • Large dispersion right next to the detector. 11
Ion Collider Ring • Circumference: 2336 m optimized for beam energy, arc dipole field and beam synchronization • 71º crossing angle optimized for sufficient length of straights Arc SC magnets • Based on the SIS 300 dipole design - 6 T central field, 2. 6 m long - 100 mm coil aperture - Two layer cos-theta magnet design - Uses Rutherford cable • Cold Mass OD: ~0. 52 m • Cryostat OD: 1. 0 m SIS 300 prototype dipole
Electron Collider Ring Reuse PEP-II equipment • Same footprint as the ion collider ring, 3 to 12 Ge. V • Added vertical chicane for enabling collisions Sp rot in ato r Arc Tune trombone, straight FODO, RF 70. 94 o in Sp tor a IP rot Forward e- detection, polarimetry magnet in Sp ator rot Future IP S rot pin ato r Arc RF system 476. 3 MHz Vacuum chamber Full energy injection from CEBAF • • Fast fill of collider ring, enable top-off, ~85% polarization 476. 3 MHz/1497 MHz = 7/22 needs special injection scheme New operation mode but no hardware modifications Fixed-target program with concurrent JLEIC operations Stored beam current subject to SR budget (10 k. W/m) Total up to 10 MW
Damping Wigglers for 3 to 6 Ge. V Electron Beam • Range of damping time (due to dipoles in arcs & spin rotators) from 7. 5 ms@12 Ge. V to 475 ms@3 Ge. V • Long damping time (3 -6 Ge. V) -Insufficient to suppress collective instabilities (include beam-beam) -Requiring strong pulsed current from CEBAF -2. 5 x 10 -4 energy spread at 3 Ge. V, prone to longitudinal microwave instability 4 60 I e-ring (A) Iinj pulsed w/o ffwd(m. A) Tinj w/o wiggler (min) Tinj w/ wiggler (min) 3, 5 3 2, 5 50 40 2 30 1, 5 20 1 10 0, 5 0 0 2 4 6 8 Beam energy (Ge. V) 10 12 Estimated JLEIC injection time (min) CEBAF Pulsed extracted beam current (m. A) JLEIC e-ring current(A) • Mitigation: using higher field monolithic wigglers for 3 to 5 Ge. V -Bring damping time below 6 Ge. V to the level of 6 Ge. V (~60 ms) -Injection time reduced to <10 min (from ~50 min) @ 3 Ge. V -For ~30 min nominal injection time, the CEBAF pulsed beam current < ~0. 25 m. A NSLS II damping wiggler Energy (Ge. V) B (T) (square wave) 3 5 6 No 1. 4 No 1. 1 No 0 32 0 16 0 Energy loss per turn (Me. V) 0. 10 0. 83 0. 76 1. 40 1. 58 Trans. damping time (ms) 475 56. 5 103 55. 7 59 3 3. 6 3. 3 Total SR power (MW) 0. 30 2. 98 2. 73 5. 04 5. 20 Energy spread (10 -4) 2. 47 9. 11 4. 12 8. 11 4. 95 Bunch length (cm) 1. 0 1. 13 0. 74 1. 03 0. 7 VRF, peak (MV) 0. 74 7. 9 6. 3 12. 5 12. 1 Synch. phase (deg) 7. 6 6. 1 7. 0 6. 4 7. 5 Bucket height/energy spread 18. 0 16. 3 24. 6 17. 8 25. 8 1 10 8 16 16 Wiggler length (m) Beam current (A) Number of cavities (PEP-II) 14
Lin talk, Thursday Electron Polarization Universal spin rotator Electron polarization design • Geometry and optics independent of energy • Goal: >70% longitudinal polarization at IPs spin flip (alternate spin orientation in bunch train) E • >85% polarization from CEBAF source, no loss in linac • Two polarized bunch trains maintained by top-off injection Ge. V 3 6 9 12 • Figure-8 helps maintaining polarization • Minimizes spin diffusion by switching polarization orientation between vertical in arcs and longitudinal in straights • Two polarization states with equal lifetimes Arc IP Dipole set 1 Solenoid 2 Spin Rotation BDL rad T·m π/2 15. 7 π/3 0 0 0. 62 12. 3 2π/3 1. 91 38. 2 π/6 15. 7 π 2π/3 62. 8 0. 62 24. 6 4π/3 1. 91 76. 4 Dipole set 2 Spin Rotation rad π/6 π/3 π/2 2π/3 Long polarization lifetime with continuous injection Equilibrium polarization Energy (Ge. V) Lifetime (hours) 3 5 7 10 12 116 9 1. 7 0. 3 0. 1 15 Pequ/P 0 (%) • A low average current (tens of n. A) injection beam can maintain a high equilibrium polarization in the whole energy range • Beam lifetime must match beam injection rate �� _������� ≪�� _�� Average injected current (n. A)
Lin talk, Thursday Ion Beam Polarization Figure-8 based polarization design • Design goal: delivering >70% polarization in transverse or longitudinal directions at IPs, with long life time 3 D spin rotator: combination of small rotations • Provides any spin orientation at any point in the ring • Figure-8 design principle: spin precessions in the left and right arc are exactly cancelled • Enabling accelerating and storing polarized deuterons • Requiring small fields to control and stabilize polarization (~3 Tm vs. < 400 Tm for deuterons at 100 Ge. V) • Frequent adiabatic spin flips Front-to-end acceleration in the collider ring Zgoubi Analytic prediction Figure-of-merit: many measurements go as L x Pe 2 x Pp 2 • White paper requirement: Pe 2 x Pp 2 ~ 0. 72 x 0. 72 ~ 0. 24 • JLEIC design: Pe 2 x Pp 2 ~ 0. 852 x 0. 852 ~ 0. 52 16 Zgoubi
Electron Cooling and Intra-beam Scatterings Estimation and optimization of IBS rate Choice: conventional/incoherent electron cooling • Proved technology but in a new parameter regime • Achieving small emittance and short bunch (~2. 5 cm) with SRF • Suppressing IBS induced emittance growth during beam store • The JLab IBS calculation code JSPEC was benchmarked recently with the BNL/e. RHIC code, and V. Lebedev’s code, • JLEIC horizontal IBS time at 100 Ge. V collision energy seems very small (Thanks to S. Nagaitsev, V. Lebedev) Multi-phase cooling scheme • A recent study has identified several areas which have unusually large contributions to the IBS rates • High cooling efficiency at low energy and/or low emittance • Pre-cooling at low energy critical for substantial reduction of total cooling time • We developed preliminary mitigation (new lattice design) Cool at reduced emittance (after pre-cool) Pre-cool when energy is low • • 8 Ge. V vs. 100 Ge. V cooling rate increased by 127 to 429 times Ring Functions Kinetic energy (Ge. V / Me. V) Proton Lead ion Electron Low Accumulation Energy of positive ions Booster Maintain emitt. 7. 9 High during stacking (injection) Energy 7. 9 booster Pre-cooling for emitt. reduction (injection) collider Maintain emitt. Up to 150 ring during collision 0. 1 (injection) 0. 054 Cooler type DC Up to 78 ERL Up to 81. 8 Removed two CCB Chromaticity Horizontal Optimized IR compensation IBS time Arc phase: 90º 120º block Shortened arc dipole: Arc 22. 8 m 15. 2 m 2. 9 min Arc DC 2 4. 3 (proton) (injection) 1. 1 (lead) 7. 9 4. 3 (ramp to) Zhang talk, EIC Cooling workshop Chromaticity compensation block IP 17 Roman pot 9. 0 min
DC Cooler and ERL Cooler DC cooler: on the board of present state-of-art • Magnetized cooling provide required cooling efficiency • Pre-cooling at 8 Ge. V/4. 3 Me. V is optimized: cooling efficiency vs. space charge constraint Bruker talk and Benson talk, EIC Cooling workshop High energy cooler: beyond state-of-art • Current: 0. 75 A / 1. 6 n. C (strong cooling in baseline) • Energy: up to 82. 5 Me. V (150 Ge. V) (must use a SRF linac) • Beam power: up to 62 MW (too big to supply and dump) Technical approaches COSY cooler 2 MV magnetized Fermilab cooler 4 MV non-magnetized • • Magnetized cooling (magnetized gun) Energy recovery Linac (ERL) (power management) Circulator ring (current management) Harmonic kicker to inject/extract from CCR Present choice of 11 circulations is optimized over beam transport in the circulator ring and kicker technology • Design just started • Option for high voltage apparatus under evaluation NICA Acceleration Column 18
JLEIC Electron Cooling Should be Sufficient Proton beam (baseline with highest luminosity) Pre-cooling at High Energy Booster • • • DC cooler: 30 m, magnetized beam • Energy: 4. 3 Me. V / 8 Ge. V, current: 3 A • Solenoid field: 1 T Bunch intensity: 1. 06 x 1010 RMS bunch length: 2. 5 cm Norm. emittance: 0. 65/0. 13 μm, energy spread: 6 x 10 -4 Beta function &dispersion inside cooler: 100 m 1. 8/0. 7 m Transverse coupling: 38% Electron beam (flat) • • Bunch size (rms): • Momentum spread: • Bunch length (rms): 2. 1 mm 6 x 10 -4 7 m Bunch intensity: 1. 6 n. C 3. 2 n. C Beer can shape, full bunch length: 5 cm Flat beam: 0. 78 mm x 0. 35 mm x 5 cm Transfer to the collider ring Bunch splitting Ramp to collision energy Horiz. Verti. Long. 1/s 1/s 1. 52 x 10 -3 2. 0 x 10 -3 0. 96 x 10 -3 Cooling 19 -1. 46 x 10 -3 -2. 1 x 10 -3 -0. 90 x 10 -3 Total -8. 5 x 10 -5 -5. 7 x 10 -5 Proton beam IBS 5. 3 x 10 -5 ERL Cooler 19 • • Length: 30 x 2 m Magnetic field: 1 T
Interaction Region and Machine-Detector Interface Morozov talk Thursday • IR designed to support full-acceptance detection unprecedented requirement • Satisfy geometric match (elements) and beam dynamics (chromatic compensation) • Crab crossing: large (50 mrad), avoiding parasitic collisions, optimizing detections spectrometers IR Layout Ion r/solenoid Central detecto bea mli ne Scattered Electron Dipole Particles Associated with struck parton electron IP forward ion detection dispersion suppressor/ geometric match Electron beamline Fo Dipole EIC Detection forward e detection Compton polarimetry Central Detector rw De ard te (i ct on or ) Particles Associated with Initial Ion 20 ions
Crab Crossing Morozov talk, Thursday Beam crossing angle is necessary • Avoid parasitic collisions due to short bunch spacing • Make space for machine elements • Improve detection and reduce detector background Without crabbing • Low luminosity • Beam dynamics issues With crabbing Beam energy Bunch frequency Crab crossing angle Betatron function at IP (βx*) Betatron function at crab cavity (βxcrab) Total transverse voltage per side No. of cavities Transverse voltage per cavity (Vcavity) Peak electric field (Ep) Peak magnetic field (Bp) • Effective head-on collision restored • Factor of 12 luminosity increase compared to uncorrected case Electron 10 Proton Units 100 200 Ge. V 952. 6 MHz 50 mrad 10 33 cm 200 450 m 2. 8 18. 7 20. 6 MV 2 10 11 1. 4 28 55. 8 1. 9 35 70. 7 Park talk, Thursday 21 1. 9 35 70. 7 MV MV/m m. T
Collective Instabilities in JLEIC Li talk, Wednesday • Preliminary estimations of collective instabilities in JLEIC were done, indicating areas vulnerable for instabilities • Various mitigation schemes will be assessed. Damping wiggler Or super-bend dipoles Landau cavity Damper Beam-beam tune spread Gap in bunch train Chromaticity Damper Clearing Electrodes Beam-beam tune spread Octuple Chromaticity Damper • Need to complete broadband narrowband impedance budget for each ring • Detailed Vlasov analysis and tracking simulations will be performed, for mitigation of each type of instability • Multi-physics effects will be carefully studied 22
EIC R&D at Jefferson Lab with Collaborations • High-Priority EIC R&D topics defined by a community review panel (Jones panel) • Accelerator R&D funded by NP – FY 17, completed - - Jones panel report Crab system design and experimental test Electron cooler design IR magnet design Simulation software development • Accelerator R&D fund by FY 18 -19 - Crab cavity operation in a hadron ring (BNL, JLab, ODU) - Strong hadron cooling • Development of innovative high-energy magnetized electron cooling for an EIC (BNL, FNAL, JLab, ODU) • Strong hadron cooling with micro-bunched electron beams (ANL, BNL, JLab, SLAC) - Magnet design • High Gradient Actively Shielded Quadrupole (BNL, JLab, LBNL) • Validation of EIC IR magnet parameters and requirements using existing magnet results (JLAB, LBNL, SLAC) - Benchmarking of EIC simulations • Development & test of simulation tools for EIC beam-beam interaction (BNL, JLab, LBNL MSU) • Experimental verification of spin transparency mode in an EIC (BNL, JLab) - Electron complex • High Bandwidth Beam Feedback Systems for a High Luminosity EIC (ANL, JLab) 23
Magnetized source development Gun HV Chamber ERL Cooler R&D magnetized beam Circulator cooling ring beam dynamics 1. 6 n. C Successfully demonstrated a magnetized beam • Up to 0. 7 n. C unch charge • 28 m. A with RF structure (568 G at photocathode) 0 1 2 3 4 5 6 7 8 9 10 11 Gun Solenoid arc Injector Design • DC photo-cathode gun with warm buncher • SRF booster has 3 single cell cavities followed by a 3 rd harmonic linearizer Energy Recovery Linac (ERL) Four 3 -cell 476. 3 MHz Cavities Two 5 -cell 1428. 9 MHz Cavities (3 rd harmonic) Harmonic RF Fast kicker 5 harmonic cavity fab Four 3 -cell 476. 3 MHz Cavities 24
Demonstration of Cooling of Ions by a Bunched e-Beam • Using a DC cooler to demonstrate cooling by a bunched electron beam • Pulsed electron beam from a thermionic gun by switching on/off the grid electrode • 1 st Experiments performed on 4/2016, follow-up experiment on 4/2017, 12/2018 A DC electron cooler at Institute of Modern Physics, China Ion Energy (i/e) Ion bunches RF voltage Stored ions Anode voltage Pulse width JLab-IMP Collaboration thermionic gun 86 Kr 25+ 5 Me. V/u & 2. 7 Ke. V 2 600 V ~108 400 V, 600 V, 800 V 300 ns to 1200 ns Transverse cooling Longitudinal cooling (reduction of bunch length) 25
Ion Polarization R&D: Testing Spin Transparency at RHIC • Figure-8 ring is in technically spin transparent mode - 3 D spin rotator: enabling rotation about any direction JLab-BNL Collaboration • Spin transparency mode is of interest to e. RHIC electron collider ring Morozov talk, Thursday Turning RHIC to Transparent Spin Mode = Figure-8 ring Racetrack with two identical Siberian snakes separated by 180 bend Plan of experiment at RHIC June 28, 2019 26
Update RF System for 100 Ge. V CM Energy • Baseline: 65 Ge. V 100 Ge. V CM energy 100 Ge. V 200 Ge. V proton new 952. 6 MHz e-ring (SCRF) 476. 3 MHz e-ring (NCRF PEP-II) 952. 6 MHz i-ring (SCRF) Rimmer talk, Wednesday 476 MHz cooler ERL (SCRF) • No major changes to ring RF systems - A few extra cavities in the electron ring - Ion ring bunching unchanged - Bunch splitting now spread over 2 rings - Ion collider ring crab voltage ~10% higher • Cooler energy: 55 Me. V 82 Me. V - Increase ERL linac energy gain - Low frequency cavities plus 3 rd harmonics - More linear bunch from the injector - Higher harmonic kicker voltage and multipole correction • Better understanding of gap transients & mitigation i-SRF NCRF 952. 6 MHz crab (SCRF) NCRF DC Harmonic Fast kicker for cooling ring HE Cooling ODU • Still need full impedance budgets Hall D • Fast feedback specifications • LLRF system specifications, concepts 27
Beyond pre. CDR: Towards Super Luminosity ~1035 cm-2 s-1 • Present JLEIC design is optimized for full acceptance detection • There are plenty luminosity-hungry experiments (eg. Double Deep Virtual Compton Scattering, DDVCS), so super high luminosity should be considered, perhaps for the 2 nd detector • Opportunity for super luminosity is very much the same • Concept: trade full acceptance for super high luminosity but still large acceptance • Short bunch length: 2. 5 cm 1. 25 cm • Doubling proton beam current: 0. 75 A 1. 25 A • Ultra small vertical beta-star: 1. 3 cm 0. 5 cm • Magnet-free detector space: 7 m ~ 4. 5 m • Ironically, ELIC (the early version of JLEIC) was designed for super high luminosity, up to ~8 x 1034 cm-2 s-1 ELIC • Need even stronger HE cooling: 1. 6 n. C 3. 2+ n. C CM energy et 200 er s t e m a r 6 pa 28 Ge. V Beam energy Collision freq Particles/bunch Beam current Polarization Bunch length Norm. emitt, x Norm. emitt, y Horizontal β* Vertical β* Beam-beam, x Laslett tune-shift Hour-glass Ge. V MHz 1010 A % cm µm µm cm cm Luminosity /cm 2 s 64. 8 p 200 e 6 476 1. 8 5. 1 1. 25 3. 6 85 85 1. 25 0. 5 1. 3 70 0. 13 7 5 5 0. 009 0. 1 0. 013 Small 0. 71 0. 75 x 1035
Beyond pre. CDR: Polarized Positrons in JLEIC • Polarized positrons generated with PEPPo (for the CEBAF polarized positron program) • Accumulator ring (500 -turn) for high polarized electron current • Limit polarized electron energy to 100 Me. V due to radiation concerns PEPPo Experiment Phys. Rev. Lett. 116 (2016) 214801 Harmonic kicker extraction 4 p. C@748. 5 MHz ~60 μs bunch train @15 -60 Hz Alternate: 100 Me. V polarized e 2 n. C bunches @ 748. 5 MHz 6 100 7 200 6 60 1 3 40 20 Positron Conversion Collection efficiency ~ 10 -3 polarization transfer: up to 75% Bunch management to CEBAF e- polarized 100 Me. V, 2 n. C @ 17 MHz, ~4 μs bunch train@2 -60 Hz 29 Polarized e+ ~50 Me. V 1 p. C @ 17 MHz 1100 m bunch train @15 -60 Hz e-ring beam current (A) Polarized e- injector 100 Me. V, 90% 10 12 200 0, 1 JLEIC polarized positron injector Accumulator Ring (35. 6 m) 500 -turn, phase-space painting Plenty of nuclear physics opportunities • Deep Virtual Compton Scattering (DVCS) • Deep Inelastic Scattering (DIS) Peak luminosity (1033 cm-2 s-1) • Beyond EIC White Paper science program, however important science • Reduced performance goals: a few of 1033 luminosity, ~40% polarization • Realization: adding a polarized positron source, using CEBAF linac 40 60 80 CM energy (Ge. V) 1, 4 1, 2 1 0, 8 0, 6 0, 4 0, 2 0 100 Me. V e- w/o damping wiggler 100 Me. V e-with damping wiggler 2 4 6 8 10 Positron energy (Ge. V) 12
Summary • JLEIC meets energy requirement and exceeds luminosity, polarization, and detection requirements • JLEIC design is stable and mature, with high level of technical readiness, low risk • JLEIC takes advantage of modern SRF electron linac, new collider rings and a green-field ion complex • Pre-CDR is completed and presently under review • Present focus: design optimization for robustness, risk reduction and cost efficiency, and accelerator R&D 30
JLEIC Collaboration S. Benson, A. Bogacz, P. Brindza, M. Bruker, A. Camsonne, P. Degtyarenko, E. Daly, Ya. Derbenev, M. Diefenthaler, D. Douglas, R. Ent, R. Fair, Y. Furletova, R. Gamage, D. Gaskell, R. Geng, P. Ghoshal, J. Grames, J. Guo, F. Hannon, L. Harwood, T. Hiatt, H. Huang, A. Hutton, K. Jordan, A. Kimber, D. Kashy, G. Krafft, R. Lessiter, R. Li, F. Lin, M. Mamum, F. Marhauser, R. Mc. Keown, T. Michalski, V. Morozov, E. Nissen, G. Park, H. Park, M. Poelker, T. Powers, R. Rajput-Ghoshal, R. Rimmer, Y. Roblin, T. Satogata, A. Seryi, M. Spata, R. Suleiman, A. Sy, C. Tennant, H. Wang, S. Wang, C. Weiss, M. Wiseman, W. Wittmer, H. Zhang, S. Zhang, Y. Zhang – Jefferson Lab Y. Cai, Y. Nosochkov, G. Stupakov, M. Sullivan - SLAC J. Fox -- Stanford Univ. J. Qiang, G. Sabbi – LBNL M. Blaskiewicz, Z. Conway, H. Huang, Y. Luo, V. Ptitsyn, Q. Wu, F. Willeke, H. Zhao – BNL K. Deitrick – Cornell Univ. , B. Mustapha, U. Wienands, R. Yashida, A. Zholents – ANL Y. Hao, P. Ostroumov, A. Plastun, R. York - Michigan State Univ. S. Abeyratne, B. Erdelyi - Northern Illinois Univ. , P. Nadel-Turonski, - Stony Brook Univ. Z. Zhao - Duke Univ. J. Delayen, B. Dhital, C. Hyde, S. De Silva, I. Neththikumara, S. Sosa, B. Terzic - Old Dominion Univ. T. Mastoridis -- Cal Poly. J. Gerity, T. Mann, P. Mc. Intyre, N. Pogue - Texas A&M Univ. D. Teytelman -- Dimi. Tel Corp. J. Breitschopf, J. Kellams, A. Sattarov, – Accelerator Technology Corp. , V. Dudnikov, R. Johnson - Muons, Inc. , D. Abell, D. Bruhwiler, I. Pogorelov - Radiasoft, G. Bell, J. Cary - Tech-X Corp. , A. Kondratenko, M. Kondratenko - Sci. & Tech. Lab. Zaryad, Russia, Yu. Filatov - Moscow Inst. of Phys. & Tech. , Russia Y. Huang, X. Ma, L. Mao, Y. Yuan, H. Zhao – IMP, China Gone but not forgotten S. Ahmed, K. Beard, L. Cardman, A. Castilla, P. Chevtsov, L. Merminga, F. Pilat, H. Sayed, C. Tsai, M. Wang, G. Wei, B. Yunn, 31
CFNS Inaugural Symposium, A. Seryi 32
EIC Science 95% of program is at CM energies below 100 Ge. V HERA: 0. 8 fb-1 integrated luminosity delivered EIC Projected Luminosity Needs Total ~700 fb-1 33
JLEIC Ion Collider Ring IP Crab cavities
Ion and Electron Interaction Region IR • High luminosity and acceptance performance in the whole energy range • Secondary focus with high dispersion Ion Electron 35
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