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Mit
glie
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er
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Beam Cooling at HESR in the FAIR Project
12th September 2011 Dieter Prasuhn
Dieter Prasuhn12. September 2011 2
HESR Consortium
ICPE-CA, Bukarest, Rumania
Rumania
Dieter Prasuhn12. September 2011 3
Outline
Design requirements for the HESR
Requirements for Cooling
p-bar injection and accumulation
Summary
Dieter Prasuhn12. September 2011 4
Modes of Operation with PANDA
Experiment Mode High Resolution
Mode
High Luminosity
Mode
Target Hydrogen Pellet target
with 4*1015 cm-2
rms-emittance 1 mm mrad
Momentum range 1.5 – 8.9 GeV/c 1.5 – 15.0 GeV/c
Intensity 1*1010 1*1011
Luminosity 2*1031 cm-2 s-1 2*1032 cm-2 s-1
rms-momentum resolution
5*10-5 1*10-4
Dieter Prasuhn12. September 2011 5
Basic Data of HESR Circumference 574 m Momentum (energy) range
1.5 to 15 GeV/c (0.8-14.1 GeV) Injection of (anti-)protons from
CR / RESR at 3.8 GeV/c Maximum dipole field: 1.7 T Dipole field at injection: 0.4 T Dipole field ramp: 0.025 T/s Acceleration rate 0.2 (GeV/c)/s
PANDAElectron cooler
Stochastic cooling
p_bar injection
long.vert.
hor.Kicker PU
Dieter Prasuhn12. September 2011 6
Cooling requirements for HESR
Internal target (d=4*1015 cm-2):• Emittance growth
• Mean energy loss
• Small momentum spread (10-5)
Accumulation of p-bars in the HESR
Dieter Prasuhn12. September 2011 7
Dieter Prasuhn12. September 2011 8
• acceleration in p-linac to 70 MeV
• multiturn injection into SIS18,acceleration to 4 GeV
• transfer of 4 SIS pulses to SIS100
• acceleration to 29 GeV and extraction of single bunch
• antiproton target and separator for 3 GeV antiprotons
• collection and pre-cooling of 108 p-bars in the Collector Ring CR
• transfer of 108 p-bars at 3 GeV to HESR
• accumulation and storage of antiprotons in the HESR
p-linacSIS18 SIS100
UNILAC
pbartarget/
separator
HESR
Antiproton Chain(Modularised Start Version)
CR
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p-bar injection and accumulation in the HESR
Dieter Prasuhn12. September 2011 10
The p-bar accumulation without RESR
• 108 p-bars collected in the CR• 10 s cooling time in CR• Transfer of 108 p-bars to HESR• In parallel:
Cooling of 108 p-bars in CR Cooling of 108 p-bars in HESR
• Transfer of 2nd CR-stack into HESR• 100 times repetition of that procedure⇒ Accumulation of 1010 p-bars in HESR in 1000 s• Acceleration, cooling, experiment
Dieter Prasuhn12. September 2011 11
The accumulation process in HESR
Simulations by H. Stockhorst and T. Katayama
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Proof of principle experiment in the ESR
Dieter Prasuhn12. September 2011 13
Properties of the ESR
circumference 108 m
transition 2.37
beam ARGON
mass number 40
charge state 18
kinetic energy 400 MeV/u
0.71
1.43
revolution period 507 ns
p/p injected 1.5*10-3
emittances hor./vert.
1 mm mrad
Dieter Prasuhn12. September 2011 14
Experimental study of accumulationin ESR with barrier bucket and stoch. cooling
Collaboration:FZJ, GSI, Tokyo, JINR, CERN
Dieter Prasuhn12. September 2011 15
Measured intensity increase byaccumulation in the ESR
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
-200 -100 0 100 200 300 400
ES
R C
urr
en
t [m
A]
Accumulation Time [s]
Fixed Barrier
• Injection every 13 s• Accumulation over 500 s• Saturation with 6*107 Ar ions
Dieter Prasuhn12. September 2011 16
Results
• The idea of injection into the barrier bucket works
• Stochastic cooling is necessary to cool injected ions into the stable area
• Electron supports the efficiency by cooling oscillations by kicker ringing
• Simulation results agree with the experimental data
Dieter Prasuhn12. September 2011 17
Question of the experimentalists:
Accumulation in HESR to more than 1010 p_bars ?
Dieter Prasuhn12. September 2011 18
Cooling time for different intensities
0
10
20
30
40
50
60
0 5 10 15 20
(p
/p)
rms
x 10
5
Time [s]
N = 108, 130 dB
N = 1010, 128 dB
N = 5 x 1010, 114 dB
N = 1011, 108 dB
• The beam from CR with p/p = 5*10-4 has to be cooled to 2.5*10-4
• Due to longer cooling times than 10 s the efficiency decreases
• 5*1010 p_bars seem to be possible within 5000 s accumulation time
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Study of internal Target effects
Dieter Prasuhn12. September 2011 20
Operation of COSY
• Circumference: 184 m• Maximum momentum: 3.7 GeV/c
(B=12 Tm)• (un-)pol. Protons and Deuterons• Electron and stochastic cooling
Design and Construction of HESR
• Circumference: 574 m• Maximum momentum: 15 GeV/c
(B=50 Tm)• (un-)pol. Anti-protons• stochastic (and electron) cooling
HESRCOSY
Dieter Prasuhn12. September 2011 21
HESR Prototyping and Tests with COSY
WASA
Barrier Bucket Cavity
Stochastic Cooling
Pellet Target
Dieter Prasuhn12. September 2011 22
Example: Beam Cooling with WASA Pellet Target
a) Injected beamb) Beam heated by targetc) + stochastic coolingd) + barrier bucket
0
1 10-7
2 10-7
3 10-7
4 10-7
5 10-7
6 10-7
1.5368 1.5369 1.537 1.5371 1.5372 1.5373
Pa
rtic
le D
en
sity
(a
rb.
units
)
f [GHz]
a) b)
d)
c)
Dieter Prasuhn12. September 2011 23
Momentum range (antiprotons): 1.5 - 15 GeV/c
Band width: 2 - 4 GHz, high sensitivity
Longitudinal cooling: Notch-Filter, ToF
Aperture of couplers: 89 mm
Parameters for the HESR stochastic cooler:
Octagonal Slot-Coupler
Octagonal Printed-Loop Coupler
Dieter Prasuhn12. September 2011 24
Stochastic cooling pickup (prototype) installed in COSY
Same sensitivity as movable /4 structures
Dieter Prasuhn12. September 2011 25
HESR Prototyping and Tests with COSY
WASA
Barrier Bucket Cavity
Stochastic Cooling
Pellet Target
Poster by Rolf Stassen
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Next step in COSY:Electron cooling up to maximum momentum
Dieter Prasuhn12. September 2011 27
Electron Cooling: Development Steps
COSY: from 0.1 MeV
to 2 MeV
HESR: 4.5 MeV
Upgradeable to 8 MeV
Technological challenge
Talk by J. Dietrich
Dieter Prasuhn12. September 2011 28
Summary
• Strong cooling is essential for HESR• Stochastic cooling is designed, prototype
structures for 2-4 GHz tested• Electron cooling in HESR will improve the
experimental conditions and the accumulation efficiency
• Tests will be performed at COSY with simultaneous electron and stochastic cooling in interaction with a thick internal target
Dieter Prasuhn12. September 2011 29
Thank you for your attention