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):