THE FAIR PROJECT AT GSI

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• THE FAIR PROJECT AT GSI
• Maria Cristina Bellachioma
• on behalf of
• GSI Helmholtzzentrum für Schwerionenforschung
• UHV Group

XIX Congresso AIV Senigallia 19-21 Maggio 2009
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• THE FAIR PROJECT AT GSI

• Research goals
• The accelerator complex
• Main technical challenges
• First stage SIS 18 upgrade
• Conclusions

• Thin film coatings production and
  characterisation
• The ion catcher system

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FAIR PROJECT- RESEARCH GOALS THE ATOMIC NUCLEUS
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FAIR PROJECT- RESEARCH GOALS NUCLEAR PHYSICS OF
THE UNIVERSE

• RESEARCH WITH ION BEAMS
• Novae, supernovae
• compressed nuclear matter
• Ion-Matter/Dense Plasmas
• r-process and rp-process
• Neutron stars strange matter
• Synthesis of light elements
• Dark matter
• Quark-gluon plasma

15 billion years
3 K
1 billion years
20 K
300.000 years
3.000 K
temperature
time
109 K
3 minutes
1012 K
1 thousandth of a second
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FAIR PROJECT- RESEARCH GOALS NUCLEAR PHYSICS OF
THE UNIVERSE
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FAIR PROJECT- RESEARCH GOALS RADIOACTIVE ION
BEAM INTENSITIES
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FAIR PROJECT- ACCELERATOR COMPLEX
SIS 100/300
SIS 18
UNILAC
Radioactive Ion Production Target
Existing facility provides ion-beam source and
injector for FAIR
HESR
Super FRS
Anti-Proton Production Target
CR
100 m
FLAIR
RESR
NESR
New future facility provides ion and
anti-matter beams of highest intensities and up
to high energies
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FAIR PROJECT- ACCELERATOR COMPLEX CHALLENGES
1. Beam intensity frontier Highest
intensities for energetic heavy ion beams. -gt
100-1000 times higher primary beam intensities
than presently 2. Beam brightness frontier
Highest phase space densities -gt Compressed
and intense primary beams -gt Cooled
radioactive ions and antiprotons
Related technical challenges - control of
intense, medium charge state heavy ion beams
o dynamic vacuum, space charge effects,
collective instabilities. - beam cooling
at high energies electron and stochastic -
fast ramping superconducting magnets -
compact rf cavities -
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FAIR PROJECT- ACCELERATOR COMPLEX REALIZATION
Stage 3
Stage 2
Stage 1
Finally the SIS 300 will be added.
The SIS 18 will be upgraded and will serve
as high energy accelerator, providing the primary
beam for the radioactive beam program involving
the Super Fragment Separator and the connected
storage rings CR and NESR
The proton linac, SIS 100, RESR and HESR
will be added.
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Heavy Ion Synchrotron SIS 18
Circumference216 m Acceleration Process More
than 100 000 cycles per second Magnetic fields
up to 1.8 T Accelerates ions up to U Energy 4
GeV (p), 2 GeV/u (Ne), 1 GeV/u (U) 24 dipole
magnets 36 focusing magnets Average total
pressure 10-11 mbar
Acceleration section
Focusing magnets
Deflecting magnets
20 speed of light
Max. 90 speed of light
Experiment
UNILAC
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Heavy Ion Synchrotron SIS 18
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PRESENT SIS 18 PERFORMANCE
5x109 U28
3x109 U73
SIS 18
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REQUIRED SIS 18 PERFORMANCE
1,5x1011 U28
2x1010 U73
SIS 18
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SIS 18 UPGRADE
Beam loss mechanisms U28 -gt U29
(stripping) U73 -gt U72 (capture)
NEG coated dipole and quadrupole chambers

• Goals
• - increase pumping speed
• - localize beam loss
• minimize desorption

Combined pumping/collimation ports behind every
dipole group
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SIS 18 UPGRADE

• Getters are materials capable of chemically
  adsorbing gas molecules. To do so their surface
  must be clean. For Non-Evaporable Getters a clean
  surface is obtained by heating to a temperature
  high enough to dissolve the native oxide layer
  into the bulk. After in-situ activation they
  provide
• Large and uniformly distributed pumping speed
  for most of the residual gases
• Monolayer surface capacity for saturating gases
• Photon and electron desorption yields lower than
  those for standard vacuum material
• Very low SEY (1.1 peak value)
• Extremely low CH4 outgassing rate 10-17 Torr l
  s-1cm-2 .

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SIS 18 UPGRADE- THIN FILM PRODUCTION DIPOLE
CHAMBERS
15 bending angle
3 m
190.7mm
70.7mm
3 m
0,3 mm wall thickness
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SIS 18 UPGRADE THIN FILM PRODUCTION
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SIS 18 UPGRADE- THIN FILM PRODUCTION QUADRUPOLE
CHAMBERS
4 m
116.36mm
200.36mm
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SIS 18 UPGRADE- THIN FILM PRODUCTION QUADRUPOLE
CHAMBERS
Coating parameters
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SIS 18 UPGRADE THIN FILM CHARACTERISATION

• The characterisation of the thin films produced
  has been carried out by
• X-ray Photoelectron Spectroscopy (XPS) for the
  activation behaviour
• Rutherford backscattering Spectroscopy (RBS) for
  the film morphology
• Elastic Recoil Detection Analysis (ERDA) for the
  chemical composition.

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SIS 18 UPGRADE THIN FILM CHARACTERISATION
X-ray Photoelectron Spectroscopy
The successful activation behaviour is proved by
the O1s and C1s peak area reduction as a function
of the activation temperature (Measurements
performed at CERN)
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
Rutherford Backscattering Spectroscopy and
Elastic Recoil Detection Analysis
Solid state detector Ø 10 mm
backscattered ions
Incident beam
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
Rutherford Backscattering Spectroscopy and
Elastic Recoil Detection Analysis
Sample
Detector
Recoil Ions
Isobuthane (30-50mbar)
Solid state detector
Incident Beam

• From the energy loss from the recoil ions into
  the isobuthane ? Z
• From the ERES ? depth information
• Element-specific depth profiling up to 1
  mm-resolution few nm.

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SIS 18 UPGRADE THIN FILM CHARACTERISATION
Set-up installed at GSI
UHV environment
RGA
Mylar windows
Ionization chamber
Experimental chamber
Xe sputter gun
Xe sputter gun (5KeV) For in-situ cleaning
Sample holder
Cleaning chamber
Sample dimensions 12x12mm
Position sensitive ionization chamber for
angular correction
M.Bender et al., Nucl.Instr.and Meth B (2007)
387-391
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
RBS Spectrum
M.C.Bellachioma et al., Vacuum 82 (2008)435-439.
The film element concentration (Ti 35, Zr 36 and
V 29 at ) and thickness (1mm) is determined by
bombarding the samples perpendicularly by a 16.8
MeV C2 beam. The projectile ions are analysed by
a semiconductor detector mounted with an angle of
about 170 in backward direction.
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
ERDA Spectrum
M.C.Bellachioma et al., Vacuum 82 (2008)435-439.
The depth profile of each different element can
be defined irradiating the samples by a 190 MeV
Xe18 at an angle of 19. The elastic scattered
recoil ions from the target were detected in a
position sensitive DE-Erest telescope under a
forward scattering angle of 35.
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SIS 18 UPGRADE THIN FILM AGEING
The vacuum chambers mounted in accelerators
undergo several venting-activation cycles ?
deterioration of the film performance is expected
? a deep investigation on the NEG ageing was
performed by ERDA.
NEG coated test chamber where 50 Ti-Zr-V coated
samples are placed
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
(M.Bender)
Injected gas CO Film thickness 1mm
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
ERDA Raw Data
(M.Bender)
Every activation cycle causes an O and C
enrichment respectively of the sample bulk and
surface.
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SIS 18 UPGRADE FIRST RESULTS ON THE ACCELERATOR
S01
VII
M.C.Bellachioma et al., Proceedings of PAC09
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SIS 18 UPGRADE THIN FILM CHARACTERISATION
S01
VAKTRAK simulation
VII
S.Wilfert et al., GSI Annual Report 2008

• Simulation parameters
• Beam pipe temperature 293 K (const.)
• Mean gas H2
• SIP-H2100 l/s STSP-H2900 l/s SNEG-H2 0,2
  l/s cm2

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SIS 18 UPGRADE THIN FILM CHARACTERISATION
Beam loss mechanisms U28 -gt U29
(stripping) U73 -gt U72 (capture)
NEG coated dipole and quadrupole chambers

• Goals
• - increase pumping speed
• - localize beam loss
• minimize desorption

Combined pumping/collimation ports behind every
dipole group
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SIS 18 UPGRADE ION CATCHER
Ion Catcher Prototype
absorber
NEG coating
Courtesy C.Omet
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SIS 18 UPGRADE ION CATCHER

• To choose the material for the ion catcher
  absorber one has to consider that
• Heavy ions with energy until 200MeV/u must be
  stopped
• A low desorption material is required.

After desorption studies ? Cu (OFHC) piece coated
with 100 nm Au

• For the prototype 2 geometries were used
• Block ? lower desorption (perpendicular
  incidence)
• Wedge ? separates the region where the losses
  occur from the circulating beam

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SIS 18 UPGRADE ION CATCHER
The diffusion of Au and Cu into each other is
prevented by a thin Ni barrier
(M.Bender and H.Kollmus)
The measurement was performed after a 350C
bakeout
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SIS 18 UPGRADE ION CATCHER
During the shutdown in 2007 two ion catcher
prototypes were implemented in the SIS18
Courtesy C.Omet
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SIS 18 UPGRADE ION CATCHER
A first experiment proved that the Block shaped
absorber should be chosen. Pressure increase in
the ion catcher chamber Wedge 3,30-11
mbar Block 6,310-12 mbar Desorption rate
measured Wedge 119 mol/Ion Block 24 mol/Ion
Courtesy C.Omet
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CONCLUSIONS

• The first stage for the realisation of the FAIR
  accelerator system foresees the SIS 18
• upgrade.
• At the moment
• 14 dipole chambers have been coated and mounted
• 6 quadrupole chambers have been coated, but just
  1 mounted
• 2 ion catcher systems have been implemented.

The accomplishment of the SIS18 UHV upgrade it is
foreseen to be finish at the end of 2009.