The LARP Collimation Program

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The LARP Collimation Program
US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC

• TASK 4 Summary
• Material Irradiation Studies
• Nick Simos
• Nikolai Mokhov

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Task 4 Irradiation Damage Assessment of LHC
collimator materials

• Scope
• Irradiate 2-D weave carbon-carbon and exact
  graphite used in Phase I jaws plus materials
  considered viable for Phase II jaws
• BNL AGS/BLIP (117 200 MeV protons)
• FNAL120 GeV protons behind pbar target planned
• Measure material properties thermal expansion,
  mechanical properties, thermal conductivity/diffus
  ivity and thermal shock
• BNL Hot Cell Sample Measurement Facility
• Resources Required
• Irradiation hot cell use fees
• Sample prep, measurement apparatus improvement
• Fraction of postdoc fraction of physicist
  travel
• Timescale
• 2005,2006 proton runs analysis into FY2007
• Status
• Phase I Carbon-Carbon irradiation completed
• Sample activation measurements completed
• Thermal Expansion of specimens started
• PLANNING of FY06 Post-Irradiation and Follow-up
  Irradiation Studies

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WHY we want to assess irradiation damage
?Graphite Properties Can Change Drastically
After Irradiation
Recent Irradiation Damage Studies Indicate
Dramatic Changes in KEY material properties
important for collimator function
Strain vs. proton pulse for Carbon-Carbon vs.
Graphite Targets
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LHC Phase I 2D carbon-carbon Irradiation Specimen
Assembly at BNL BLIP Facility
117 MeV or 200 MeV BNL LiNAC Protons (depending
on the isotope production requirements downstream)
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LHC Phase I 2D carbon-carbon BNL IrradiationBeam
Conditions Integrated Beam Exposure
Integrated 2D carbon Exposure micro-Amp Hours gt
100,000
Beam Spot during the short 200 MeV Irradiation
at the end of the cycle
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LHC Phase I 2D carbon-carbon Post Irradiation
PhaseDisassembly and Physical Examination
Preliminary Assessment 2D CC specimens normal to
the planes of reinforcing fibers and close to the
center of the beam (receiving high dose)
experienced degradation. Less degradation was
seen in the specimens along the
reinforcement. NOTE Total dose received MUCH
HIGHER than what LHC collimator jaws will see.
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LHC Phase I 2D carbon-carbon Post Irradiation
PhaseACTIVATION and Irradiation Damage
Assessment (dpa)
Irradiation Damage (dpa) Assessment STATUS MCNPX
Monte Carlo Code has been used along with the
appropriate Damage Cross-Section to generate
preliminary results of damage in terms of
dpa. The geometrical arrangement is being refined
in the model used for final estimates (final
results Q1 of FY06).
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LHC Phase I 2D carbon-carbon Post-Irradiation
Evaluation at the BNL Hot Cell Facilities
Dilatometer Arrangement at BNL Hot Cell
Facility Used in Post-Irradiation Study
Company provided data on the 2D CC Material
irradiated NOTE Results shown are in terms of
Coefficient of Thermal Expansion
Results on non-irradiated 2D CC confirming the
company provided data Note Results above are in
terms of thermal strain (not CTE)
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LHC Phase I and Phase II Planned Activities

• Irradiation Damage Assessment of 2D Carbon of
  Phase I
• Using the nickel foils of the irradiation
  assembly and deduce exact beam position and
  profile through
• radiographic analysis. These results, combined
  with the exposure record will provide the number
  of
• protons seen by the different specimens.
• USE results for irradiation damage (dpa)
  estimation.
• Refine model for dpa estimation (based on MCNPX
  code and damage cross-sections)
• Isotope generation
• The isotopes generated in the composite will be
  fully assessed.
• Preliminary results show that the predominant is
  Be-7. Such result is important for collimator
  servicing.
• CTE set-up for 250 C thermal Cycling
• Thermal expansion measurements with cyclic
  temperature profile between room temperature
• and 250 degrees C (as requested by LHC collimator
  group.
• Measure effects of irradiation on the coefficient
  of thermal expansion (CTE).
• Upgrade Apparatus to Measure Irradiation Effects
  on
• Thermal Condutivity/Diffusivity
• Electrical Resistivity

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LHC Phase I and Phase II Planned Activities

• Irradiation Effects on
• Thermal Condutivity/Diffusivity
• Electrical Resistivity
• FNAL Irradiation Experiment at Pbar Target Area

PRELIMINARY Layout for FNAL Pbar Target
Irradiation
This is WHY we want to do Conductivity/Resistivity
Irradiation Assessment