The HESR

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The HESR

• on behalf of the
• HESR-Consortium
• FZJ, GSI, TSL

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Artists view of FAIR and GSI
High Energy Storage Ring
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Outline

• Experimental requirements for the HESR
• System layout
• Beam cooling in the HESR
• Cycle description
• Summary
• Outlook

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Requirements for the layout of the HESR

• HESR is designed to fulfill the requirements of
  PANDA
• antiprotons in the momentum range
• 1.5 GeV/c lt p lt 15 GeV/c (800 MeV lt T lt 14.2
  GeV)
• High luminosity
• High momentum resolution
• Long beam life time

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Experimental Requirements
PANDA (Strong Interaction Studies with
Antiprotons) Momentum range 1.5 to 15 GeV/c
(Protons and Antiprotons)
Effective target thickness (pellets) 41015 cm-2 Beam radius at target (rms) 0.3 mm Effective target thickness (pellets) 41015 cm-2 Beam radius at target (rms) 0.3 mm Effective target thickness (pellets) 41015 cm-2 Beam radius at target (rms) 0.3 mm
Momentum range Number of antiprotons Peak luminosity Momentum resolution (rms) Beam cooler High Resolution Mode 1.5 - 8.9 GeV/c 1010 21031 cm-2s-1 ?p/p 410-5 Electron ( 8.9 GeV/c) High Luminosity Mode 1.5 15 GeV/c 1011 21032 cm-2s-1 ?p/p 110-4 Stochastic ( 3.8 GeV/c)
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• The p -beam is injected from RESR at 3.8 GeV/c
• Protons can be injected from
• RESR at reversed field polarities
• SIS 18 at 12.7 Tm with same field polarity, but
  opposite direction

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HESR Basic Data

• Circumference 574 m
• Momentum (energy) range
• 1.5 to 15 GeV/c (0.8-14.1 GeV)
• Injection of (anti-)protons from RESR at 3.8
  GeV/c
• Acceleration rate 0.1 (GeV/c)/s
• Electron cooling up to 8.9 GeV/c (4.5 MeV
  electron cooler)
• Stochastic cooling above
• 3.8 GeV/c

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Magnet System of HESR

• Ring mainly cold
• 8 warm insertions
• cryogenic bypasses for warm sections

Arcs 4 fold symmetry 32 Dipoles 50 Quadrupole, 3
families 32 Sextupoles, 2 families Straights 42
Quadrupoles, 14 families
Dipoles 48 3.6 T 4.32 m
Quadrupoles 112 60 T/m 0.6 m
Sextupoles 48 460 T/m2 0.6 m
Correctors 56 250 mT 0.3 m
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Beam Cooling in the HESR

• Decrease the momentum spread to the required
  value for the high resolution mode
• Counteract the emittance growth due to multiple
  Coulomb scattering and energy loss straggling

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WHY ELECTRON COOLING AT HESR?

• Users want resolution near what corresponds to
  ?p/p 10-5. This can not be achieved with
  stochastic cooling alone.
• Easy cooling of bunched beam
• Cooling rate is independent of antiproton
  intensity, no degradation of cooling at higher
  intensity
• Possibility for absolute calibration of
  antiproton energy(by means of H--beam and
  7Li(p,n)-reaction Ethreshold 1880.3558 ?
  0.0812 kV)
• Possibility for cooling below 3 GeV, which is
  difficult with stochastic cooling in HESR due to
  band overlap.

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HESR Electron Cooler
Parameters for the HESR electron cooler Momentum
range (antiprotons) 1.5 8.9 GeV/c Electron
energy 0.45 4.5 MeV Electron current 0 - 1
A Electron beam radius 5 mm Magnetic Field
(cooling section) 0.2 T Magnetic field
straightness (rms) Br/B lt 10-5 rad Cooling
length Leff 20 to 22 m
High-Voltage Column
Cooling Section
The Svedberg LaboratoryUppsala University
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THE HESR ELECTRON COOLER
e-beam parameters HESR FNAL
Energy (MeV) 0.45 - 4.5 4.3
Current (Amp) 1 0.5
Solenoid field (T) 0.2 0.01
Straightness (µrad rms) 10 200
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CHALLENGES

• Severe demands of straightness of the magnetic
  field. 10-5 rad rms to achieve good cooling
• Care must be taken in order to achieve an
  electron beam with sufficiently small coherent
  cyclotron motion and envelope oscillations.
• Precise control of the electron beam energy.
• Collector with high efficiency. 99.999
  collection of the recirculating electrons.

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HESR Stochastic Cooler
Parameters for the HESR stochastic cooler
Momentum range (antiprotons) 3.8 - 15 GeV/c
Band width 2 - 4 GHz, high sensitivity Longitudi
nal cooling Time-of-Flight and
Notch-Filter Method Aperture of couplers 89 mm
Octagonal Slot-Coupler
Octagonal Printed-Loop Coupler
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Hardware Developments

• Structure tests in COSY with protons
• Design of test-tank finished including the
  slot-coupler, the printed loop coupler and
  additional space for GSI structures
• Construction started
• Installation in COSY End of 2007

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Cycle Description
HESR Nominal Cycle
Cycle description - Momentum 1.5 15 GeV/c -
Pre-cooling at 3.8 GeV/c 30 60 sec - Ramping
time (25 mT/s) 25 - 110 s - Beam steering and
focussing 20 s - Total beam preparation time
100 300 sec - Beam lifetime (1/e) 1500 7100
sec Cycle average luminosity - Production rate
1107 /s (1.5 15 GeV/c) 0.34 - 1.51032
cm-2s-1 - Production rate 2107 /s (1.5 15
GeV/c) 0.67 - 1.61032 cm-2s-1Equilibrium
momentum spread HR-mode ?p/p 410-5 HL-mode
?p/p 10-4

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The beam life time is determined by

• The hadronic interaction
• Multiple scattering
• Mean energy loss
• Single Coulomb scattering
• Large energy loss probability

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Losses due to hadronic interaction
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Total p -- p-bar cross section
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Total loss probability for given parameters and a
Hydrogen target of 41015 atoms/cm2
Total loss probability
Hadronic interaction
Relative momentum loss Dp/p gt 110-3
Single Coulomb scattering gt1.3 mrad
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1/e-beam life time t as function of momentum for
a 41015 cm-2 H-target
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Luminosity as function of time in the cycle
P 9 GeV/c frev. 500 kHz H-target 41015
cm-2 Np-bars 1011
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The Cycle Averaged Luminosity
Averaged luminosity as function of the cycle time
Luminosity as function of time in one cycle
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Average Luminosity strongly depends on thep-bar
production rate
Averaged luminosity, p-bar production rate 2107
s-1
Averaged luminosity, p-bar production rate 1107
s-1
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Summary

• The lattice of the HESR fulfills the experimental
  requirements
• The design with super-conducting magnets is
  finalized
• The cooling methods are discussed and finalized
• There was a strong recommendation by the last
  TAC-meeting to consider also a normal-conducting
  lattice

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Outlook

• 2005 2008 RD programme
• (partially funded by Design Study EU-FP6)
• Technical Design Report
• End of 2007 Design Review
• 2008 Authorisation (by the board of management)
• 2008 2014 Construction and installation
• Construction 2008 2010
• Series production 2010 2012
• Installation and test 2013 2014
• End of 2014 Commissioning
• 2015 Operation starts

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Steps in View of2nd Generation Experiments

• for production of polarized antiprotons
• APR and
• CSR
• For PAX in its optimum stage
• asymmetric collider
• Upgrade of the electron cooler to 8 MeV

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The symmetric collider scheme worked out by
Yuri Shatunov