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Accelerators COSY and HESR

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1 Accelerators COSY and HESR
March 15, | Andreas Lehrach

2 Cooler Synchrotron COSY
Outline Introduction Cooler Synchrotron COSY Prototyping and Accelerator Physics Polarized Beams Preparation for Storage Ring EDM High-Energy Storage Ring HESR Beam Dynamics Simulations Design Work Summary/Outlook

3 Cooler Synchrotron COSY
Siberian Snake Ions: (pol. & unpol.) p and d Momentum: 300/600 to 3700 MeV/c for p/d, respectively Circumference of the ring: 184 m Electron Cooling up to 550 MeV/c Stochastic Cooling above 1.5 GeV/c 2MV Electron Cooler  Major Upgrades

4 Prototyping and Accelerator Physics
Siberian Snake (2013) Pellet Target Residual Gas Profile Monitor RF Dipole WASA Barrier Bucket Cavity Stochastic Cooling 2 MeV e-Cooler (2012/13) RF Solenoid 4

5 Magnetized High-Energy Electron Cooling: Development Steps
HESR: 4.5 MeV COSY: from 0.1 MeV to 2 MeV Upgradable to 8 MeV Technological challenge Benchmarking of cooling forces Installation at COSY started 5

6 Example: Beam Cooling with WASA Pellet Target
Injected beam Beam heated by target + stochastic cooling d) + barrier bucket 6

7 Polarized Beams at COSY
Tune-Jump Polarization during acceleration Qy 7-Qy 9-Qy DQy 0+Qy gG=5 2+Qy 8-Qy gG=6 gG=4 10-Qy 1+Qy Length 0.6 m Max. current ±3100 A Max gradient 0.45 T/m Rise time 10 μs Intrinsic resonances  tune jumps Imperfection resonances  vertical orbit excitation P > 75% at 3.3 GeV/c

8 Physics at COSY using longitudinally polarized beams: Snake Concept
Should allow for flexible use at two locations Fast ramping <30s Integral long. field >4.7 T m Cryogen-free system? ANKE PAX PAX ANKE Bdl (Tm) COSY Injection Energy 45 MeV 1.103 pn→{pp}sπ- at 353 MeV 3.329 PAX at COSY 140 MeV 1.994 PAX at AD 500 MeV 4.090 Tmax at COSY 2.88 GeV 13.887

9 Siberian Snake at COSY Installation at COSY in summer 2013
Superconducting 4.7 Tm solenoid is ordered. Overall length: 1 m Ramping time 30 s Spin dynamics and longitudinal polarized beams for experiments Installation at COSY in summer 2013

10 Polarization of a Stored Beam by Spin-Filtering
Experiment with COSY / schematic COSY Cycle / schematic Spin- flipper Results COSY Cycle Stacking injection at 45 MeV Electron cooling on Acceleration to 49.3 MeV Start of spin-filter cycle at PAX: s PAX ABS off ANKE cluster target on Polarization measurement (2 500 s) at ANKE Spin flips with RF Solenoid New cycle: different direction of target polarization 10

11 Facility for Antiproton and Ion Research
p-Linac HESR SIS18 SIS100 CR/RESR Antiprotonen Production Target Linac: 70MeV protons, 70mA, ≤4Hz SIS 18: 5·1012 protons/cycle SIS 100: 4·1013 protons/cycle 29GeV protons bunch compressed to 50nsec Production target: 2·108 antiprotons/cycle 3% momentum spread CR: bunch rotation and stochastic cooling at 3.8GeV/c, 10s RESR: accumulation at 3.8GeV/c

12 HESR with PANDA and Electron Cooler
COSY HESR HESR COSY 575 m Circumference 184 m 1.5 – 15 GeV/c Momentum 0.3 – 3.7 GeV/c up to 9 GeV/c Electron Cooling up to 0.5 GeV/c Full range Stochastic Cooling 1.5 – 3.7 GeV/c Jülich is the leading lab of the HESR Consortium: Germany (Jülich (90%), GSI, Mainz), Slovenia and Romania 12

13 Criteria for the Layout of the HESR
HESR design driven by the requirements of PANDA: Antiprotons with 1.5 GeV/c ≤ p ≤ 15 GeV/c High luminosity: 2·1032 cm-2s-1 Thick targets: 4·1015 cm-2 High momentum resolution: Δp/p ≤ 4·10-5 Phase space cooling Long beam life time: >30 min 13

14 Beam Dynamics Simulations
Beam injection and accumulation: stacking injection concept (Simulation codes by T. Katayama and H. Stockhorst) Dynamic aperture calculations and closed-orbit correction: steering and multipole correction concept (MAD-X, SIMBAD based on ORBIT) Beam losses at internal targets / luminosity estimations: particle losses (hadronic, single Coulomb, energy straggling, single intra-beam) (Analytic formulas) Beam-cooling / beam-target interaction / intra-beam scattering: beam equilibria (BetaCool, MOCAC, PTARGET, Jülich stochastic cooling code) Ring impedance: RF cavities, kicker etc. (SIMBAD based on ORBIT) Trapped ions: discontinuity of vacuum chamber, clearing electrodes (Analytic codes)

15 Injection and Accumulation
Beam accumulation in HESR required for modularized FAIR start version Barrier Bucket and stochastic cooling will be used to accumulate antiprotons in HESR Proof of principle measurement

16 Future HESR Upgrade Options
Polarized Proton-Antiprotons Collider 15 GeV/c – 3.5 GeV/c Spin Filtering Antiproton Polarizer (APR) Asymmetric Collider Polarized Electron-Nucleon Collider ENC Accelerator Working Group:

17 Prototyping and Accelerator Physics at COSY
Summary / Outlook Prototyping and Accelerator Physics at COSY Detector tests for PANDA and CBM Preparation for HESR: High-Energy Electron Cooling and High-Bandwidth Stochastic Cooling Internal Targets, RF Manipulation techniques  COSY is essential to develop and establish these techniques for HESR Polarized beams at COSY Polarizing stored Antiprotons by spin-filtering R&D work for storage ring EDM searches of charged particles First direct EDM measurement, ideal EDM injector  COSY is essential to perform R&D work for PAX and EDM HESR project status New HESR beam accumulation scheme due to modularized start version of FAIR Design work of the HESR is finalized and the construction phase started Main HESR components are ordered (dipoles, quadrupoles, ... )  corresponds to roughly 30% of total project costs

18 No imperfection resonances
Siberian Snake spin rotation χ spin- and particle motion Full snake: χ = 180°  νsp = ½ Spin tune independent of beam energy No spin resonances except snake resonances: νsp = ½ = k ± l∙Qx ± m∙Qy Partial snake: χ < 180°  νsp ≠ k Keeps the spin tune away from integer No imperfection resonances Chi

19 New 2 MV Electron Cooler at COSY
BINP Novosibirsk Energy Range: MeV High-Voltage Stability: < 10-4 Electron Current: A Electron Beam Diameter: mm Cooling section length: m Magnetic field (cooling section): kG Installation at COSY started

20 Stochastic Cooling System
Cooling Bandwidth (2 – 4) GHz Pickup and Kicker Structures: Circular Slot Type Couplers*) Aperture 90 mm Length per cell 12.5 mm 88 pickup cells Total length: 1100 mm Zero dispersion at pickup and kicker Noise temperature pickup plus equivalent amplifier noise: 40 K Momentum range 1.5 GeV/c to 15 GeV/c Above 3.8 GeV/c: Filter Cooling Below 3.8 GeV/c: TOF Cooling R. Stassen, FZJ

21 Spin Manipulation in COSY
Jump Quadrupole Air coil, length 0.6 m Current ±3100 A, gradient T/m Rise time 10 μs, fall time 10 to 40 ms RF Solenoid Water-cooled copper coil in a copper box, length 0.6 m Frequency range roughly 0.6 to 1.6 MHz Integrated field ∫Brms dl ~ 1 T·mm RF Dipole 8-turn water-cooled copper coil in a ferrite box , length 0.6 m Frequency range roughly 0.12 to 1.6 MHz Integrated field ∫Brms dl ~ 0.1 T·mm Spin coherence time depends on dp/p (much better for cooled beams) Sextupole correction of non-linear fields (done next beam time in week 10-19) Is there a difference between spin coherence time w/o RF flipper Siberian Snake (ordered) Fast-Ramping Superconducting Solenoid, length 0.98m Ramp time to maximum 30s Integrated field ∫Brms dl = 0.47 Tm

22 COSY Upgrade 1. Improved closed-orbit control system for orbit correction in the micrometer range  Increasing the stability of correction-dipole power supplies  Increase number of correction dipoles and beam-position monitors (BPMs)  Improve BPM accuracy, limited by electronic offset and amplifier linearity  Systematic errors of the orbit measurement (e.g., temperature drift) 2. Alignment of Magnets and BPMs  More precise alignment of the quadrupole and sextupole magnets  BPMs have to be aligned with respect to the magnetic axis of these magnets 3. Beam oscillations  Excited by vibrations of magnetic fields induced by the jitter of power supplies  Coherent beam oscillation 4. Longitudinal and transverse wake fields  Ring impedances

23 HESR Layout Main machine parameter Momentum range 1.5 to 15 GeV/c
Circumference 574 m Magnetic bending power 50 Tm Dipole ramp 25 mT/s Acceleration rate 0.2 (GeV/c)/s Geometrical acceptances for βt = 2 m horizontal 4.9 mm mrad vertical 5.7 mm mrad Momentum acceptance ± 2.5×10-3

24 Dipoles Quadrupoles Number 44 Magnetic length 4.2 m
Deflection angle ° Max B-field T Min B-field T Aperture mm Quadrupoles Number Magnetic length m Iron length (arc) m Max gradient T/m Aperture mm

25 Luminosity Considerations (Full FAIR version)
Antiproton production rate: 2·107 /s Pellet target: nt=4·1015 cm-2 Transverse beam emittance: 1mm·mrad Longitudinal ring acceptance: Δp/p = ±10-3 Betatron amplitude at PANDA: 1m Circulating antiprotons: Relative Loss Rate Scattering Process 1.5 GeV/c 9 GeV/c 15 GeV/c Hadronic Interaction 1.8·10-4 1.2·10-4 1.1·10-4 Single Coulomb 2.9·10-4 6.8·10-6 2.4·10-6 Energy Straggling 1.3·10-4 4.1·10-5 2.8·10-5 Touschek (Single IBS) 4.9·10-5 2.3·10-7 4.9·10-8 Total relatve loss rate 6.5·10-4 1.7·10-4 1.4·10-4 1/e Beam lifetime / s ~ 1540 ~ 6000 ~ 7100 Cycle averaged luminosity - Momentum 1.5 GeV/c: 0.3 – 0.7 · 1032 cm-2s-1 - Momentum: 15 GeV/c: 1.5 – 1.6 · 1032 cm-2s-1 (Production rate: 1 – 2 · 107 /s) A. Lehrach et al., NIMA 561 (2006) O. Boine-Frankenheim et al., 560 (2006) F. Hinterberger, Jül-4206 (2006)

26 Cooled Beam Equilibria
Beam cooling, beam-target interactions, intra-beam scattering rms relative momentum spread p/p Electron cooled beams HR mode: ·10-6 (1.5 GeV/c) to 2.7·10-5 (8.9 GeV/c), and 1·10-4 (15 GeV/c) HL mode: <10-4 Stochastic cooled beams HR mode: 5.1·10-5 (3.8 GeV/c), 5.4·10-5 (8.9 GeV/c), and 3.9·10-5 (15 GeV/c) HL mode: ~10-4 Transverse stochastic cooling can be adjusted independently D. Reistad et al:, Proc. of the Workshop on Beam Cooling and Related Topics COOL2007, MOA2C05, 44 (2007) O. Boine-Frankenheim et al., A 560 (2006) 245–255 H. Stockhorst et al., Proc. of the European Accelerator Conference EPAC2008, THPP055, 3491 (2008).

27 Expected Pressure Distribution and Neutralization Factor
PANDA IP The mean time for residual gas ions in the antiproton beam Tc (clearing time) in relation to the time of ion production Tp: Average distance of clearing electrodes of 10 m, with a clearing voltage of 200 V  Emittance Growth  Incoherent Tune Shift  Beam Instabilities

28 Coherent Beam Instabilities
Resonance frequencies: (8 − Qx) = and (8 − Qy) = , (9 − Qx) = and (9 − Qy) = Bounce frequencies of transverse H+2 ion oscillations represented as tune numbers qx,y horizontal vertical Beam momentum p = 15 GeV/c (n − Q)ω0 (’slow wave’ frequency) (n + Q)ω0 (’fast wave’ frequency) Since the real part of Z(ω) + Zi(ω) is positive the fast-wave mode with the sideband frequency ω = (n + Q)ω0 is always stable [16]. Here, ω0 is the revolution frequency, Q the betatron tune and n an integer with n > −Q. Without Landau damping, i.e. without any frequency spreads the slow-wave mode with ω = (n − Q)ω0 is always unstable. Here, n is an integer with n > Q. Thus, dangerous coherent oscillations can occur if the trapped ions oscillate at frequencies near the sideband frequencies (n − Q)ω0. [16] P. Zhou, A Study of Ion Trapping and Instability in the FERMILAB Antiproton Accumulator, PhD Thesis, Northwestern University (1993). Estimates for beam instabilities F. Hinterberger, Ion Trapping in the High-Energy Storage Ring HESR, JÜL-Report 4343 (2011)

29 Dynamic Aperture (Optimized)
16 mm mrad Orbit diffusion coefficient D Orbit diffusion coefficient (e.g. after 1000 and 2000 turns):

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