# Presentation: 431512

## The LARP Collimation Program

**TASK 4 Summary**
**Material Irradiation Studies**
_**Nick Simos**_
- Nikolai Mokhov

*BNL - FNAL- LBNL - SLAC*

_**US LHC Accelerator Research Program**_

## 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 p****roperties: 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 + full-time technician at FNAL
_**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

## 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**

## 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)**

## LHC Phase I 2D carbon-carbon BNL IrradiationBeam Conditions – Integrated Beam Exposure

**Beam Spot during the short 200 MeV **
**Irradiation at the end of the cycle**

**Integrated 2D carbon Exposure:**
**micro-Amp Hours > 100,000**

## 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).**

- In addition, MARS15 provides
- Full predictive power on DPA
- For beam tests at BNL and
- Especially at high energies
-  at FNAL

## LHC Phase I 2D carbon-carbon Post-Irradiation Evaluation at the BNL Hot Cell Facilities

**Company provided data on the 2D CC Material irradiated**
**NOTE: Results shown are in terms of Coefficient of Thermal Expansion**

**Dilatometer Arrangement at BNL Hot Cell Facility**
**Used in Post-Irradiation Study**

**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 and MARS15 codes 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 120-GeV proton beam and assess irradiation damage
- 	as well as damage dependence on particle energy spectra

## LHC Phase I and Phase II Planned Activities 

_***Irradiation Effects on:***_
*Thermal Condutivity/Diffusivity*
*Electrical Resistivity*
_***FNAL Irradiation Experiment at Pbar Target Area***_

**This is WHY we want to do Conductivity/Resistivity**
**Irradiation Assessment**

**PRELIMINARY Layout for FNAL Pbar Target Irradiation**

## FERMILAB IRRADIATION FACILITY

## FERMILAB IRRADIATION FACILITY