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

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

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

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)

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

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.

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).

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)

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

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