1. BNL Irradiation Studies and the LHC Collimators
Nick Simos, BNL May 16, 2006

2. R & D Overview
PHASE I: Irradiation effects on 2D-weaved CC composite for Phase I LHC Collimators
(exposure reached ~ 108,000 μA-hrs !!!!)
PHASE II: Receiving protons since 11 AM, May 4, 2006 … (thus far accumulated ~ 23,000 μA-hrs and going…)

3. LHC-relevant Materials
PHASE II - Overview
PRIMARY
Pure Copper (annealed)
Glidcop_15AL – Cu alloyed with .15% Al (axial cut and transverse cut)
3D-weaved Carbon-Carbon Composite
2D-weaved Carbon-Carbon
SECONDARY
Super-Invar (most challenging of all materials in matrix!)
Re-introduction of irradiated material into the assembly including annealed and non-annealed specimens
Toyota “Gum Metal”
(90% cold-worked plus typical grade tested during Phase II)
Two Graphite Grades (IG-43 and IG-430)
ALSO
Ti Alloy (6Al-4V)
Bonded graphite to Titanium and Copper
(45 degree bond orientation and 90-degree orientation)
Tungsten
Tantalum
Miscellaneous materials (AlBemet; Vascomax)
Nickel-Plated Aluminum of the NuMI horn (expose it to more irradiation and compare the surface degradation between the two irradiation phases)
Examine electrical resistivity degradation
Examine effects of irradiation on thermal conductivity
LHC-relevant Materials

5. Graphite vs. Carbon-Carbon
3D-weaved CC
2D CC (fibers only along parallel planes)
CC superior to graphite in thermal shock
Serious DAMAGE of 2D CC after heavy irradiation exposure
Annealing (reversing irradiation damage) of 3D CC
Dramatic Irradiation Effects on Graphite Conductivity
Annealing is also exhibited by 2D CC !!!
MOST IMPORTANTLY: CTE goes down with irradiation
along weak direction

7. The Beam is ON (as of Thursday, May 4, 11 AM!!!!

8. Thermal Expansion of Annealed Copper and Glidcop_AL15
Analysis of Non-irradiated Material – Baseline Establishment
BNL experiment confirmed the CTE value of Copper indicating stability and precision of the experimental process

10. Re-considering Super-Invar – Why?
Initial study showed that low CTE disappears with irradiation
Things did not look promising.
Re-examination reveals self-annealing characteristics !!
Irradiated invar undergone annealing through thermal cycling
Has gone back in the beam for more irradiation.