Transcript simos-mokhov.ppt

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 + 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
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
AC150 and AC200 Processed @ 2,500 C - C.T.E. (10-6/K)
12. 00
10. 00
AC150 Lengthwise (in x
C. T. E. ( 10-6/K)
8. 00
and
y)
AC150 Thickness-wise
( i n
z)
6. 00
AC200 Lengthwise (in x
and
y)
AC200 Thickness-wise
4. 00
( i n
z)
2. 00
0. 00
-2.00
50
100 150 200 250 300 350 400 450 500 550 600
(degree C)
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