1. The LARP Collimation Program
US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC
The LARP Collimation Program
TASK 4 Summary
Material Irradiation Studies
Nick Simos
Nikolai Mokhov

2. 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/diffusivity 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

3. Strain vs. proton pulse for Carbon-Carbon vs. Graphite Targets
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

4. 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)

5. Integrated 2D carbon Exposure: micro-Amp Hours > 100,000
LHC Phase I 2D carbon-carbon BNL Irradiation Beam Conditions – Integrated Beam Exposure
Integrated 2D carbon Exposure:
micro-Amp Hours > 100,000
Beam Spot during the short 200 MeV
Irradiation at the end of the cycle

6. LHC Phase I 2D carbon-carbon Post Irradiation Phase Disassembly 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.

7. LHC Phase I 2D carbon-carbon Post Irradiation Phase ACTIVATION 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).

8. 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)

9. 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
PLAN and Conduct New Irradiation Experiments that include Phase II Materials:
- Irradiate At BNL BLIP candidate materials of Phase II (copper, superInvar, Inconel, 3D CC, etc.)
- Irradiate at FNAL at the Pbar target area using much higher energy protons and assess irradiation damage
as well as damage dependence on proton energies

10. 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