BNL Irradiation Facility Use Collimator Materials for LHC Luminosity Upgrade

BNL_LHC_December 3, 2012

ObjectivesStudy irradiation damage of energetic protons (and neutrons) on materials

under consideration for the LHC collimation linked to the LHC luminosity upgrade

Perform irradiation and post-irradiation studies using the BNL irradiation facility capable of providing fluences representative of those anticipated at the LHC

It has been shown in recent studies that damage in the range up to 200 MeV exceeds the damage anticipated at 120 GeV fro the same fluence. It is expected, therefore that that will hold true for the even higher LHC energy (simulations to be performed for confirmation)

While a new set of advanced materials are being considered, further analyze materials irradiated at BNL in support of the LHC design phase which include the 2D C/C of the primary collimator, graphite, copper and glidcop, super-Invar and gum metal.

Focus on irradiation-induced damage and degradation of key physical and mechanical properties as well as damage annealing potential

Irradiation at the BNL Accelerator Complex

Irradiation at BLIP (up to 200 MeV or spallation neutrons from 112 MeV protons)

Power ~ 28 kW

Typical proton beam profile

Mixed-spectrum (neutron-dominated) Irradiation at the BNL Accelerator Complex

118 MeV protons from Linac

LHC Collimation Upgrade Material StudyFour (4) materials will make up the irradiation array:

1) Molybdenum-Graphite compound2) Molybdenum3) Glidcop4) Copper-diamond

Of interest are irradiation-induced damage and degradation of key physical and mechanical properties - thermal conductivity - thermal expansion and dimensional changes - stress-strain behavior and ductility loss - annealing temperatures for damage reversal

Obtaining of property changes as a function of dose and/or temperature

Sought are effects from doses equivalent to what will be experienced at the upgraded LHC

Objective is to utilize the deduced information in the upgraded collimator design.

LHC Collimation Upgrade Material Study (continued)

The new effort will also include:

Completion of post-irradiation analysis of previously irradiated copper and Glidcop as well as copper bonding with graphite and titanium alloy (bonding or brazing degradation in terms of structural integrity and thermal conductivity)

Study the effects of irradiation and temperature on Molybdenum and Molybdenum/graphite compound and compare with results obtained from the irradiation of other refractory metals such as Ta and W.

In particular pay close attention to possible fcc bcc transitions that have been shown to occur in W and Ta that may significantly impact the dimensional stability of Mo and Mo-Graphite compound

Draw from the study of irradiation impact on brazing or bonding of dissimilar materials (see Figs of next page)

Study the impact of neutron dominated spectrum vs. proton spectrum on the candidate materials

Benchmark the irradiation/post-irradiation study on Copper-diamond against similar studies at other institutions (i.e. Kurchatov)

BNL_LHC_December 3, 2012

What Needs to be DONE

Design, and fabricate the test specimensall materials 2-types of each material to study different properties (Tensile & CTE)

Design and fabricate the test specimen capsulesCapsule with either vacuum or inert gas volume that will contain an array of specimens laid out in a way that

(a) will not change the beam profile for downstream isotope production(b) will degrade the beam energy uniformly

(c) will allow for some irradiation temperature control or quantification(d) precise energy deposition calculations will be needed ahead of time(e) energy depositions will feed a high-fidelity thermo-mechanical analysis that will help

assess the expected temperatures during irradiation and provide the basis for iterative and optimized design of the experimental configuration

Decide on the PEAK FLUENCE (or peak dpa) we need to expose the collimator materials primarily under proton irradiation which is the phase that disrupts the isotope production operation at BNL Isotope Facility (BLIP) and also is the one operation that is costly and will affect the budget for the effort.

Neutron irradiation (a) does not impact isotope production and (b) will run for longer in the spallation field behind the isotope targets

BNL_LHC_December 3, 2012

What Needs to be DONE (cont.)

Decide on the amount of test material specimens and the different dpa we will like to observe the changesFrom previous studies BNL (Simos) has created a program that can help the iterative process of proton beam degradation from the incoming proton energy which could be 164 MeV, 181 MeV or 200 MeV down to the required 112.6 MeV for the isotope production)

Based on the decision where to run the primary beam (164, 181 or 200 MeV) and the materials before the isotope targets, CERN team should run FLUKA or GEANT and get energy deposition and confirm energy degradation to 112.6 MeV

BNL will design the array using the INPUT from CERN and perform detailed thermomechanical analysis to see what will be the irradiating temperatures of the specimens within the capsules (vacuum or inert gas). Of course CERN team can work with BNL on this important task.

The importance of understanding the irradiation temperature is that heat transfer will take place through conductance (contact between specimens and the windows of the capsules which will be cooled on the outside, and this puts a lot of uncertainty in the performance of the heat transfer path). Temperatures can get high because of the 25 kW beam on targets. Iteration on this work will finalize the arrangement of the capsules and specimens within the capsules.

Irradiation-induced degradation

BNL will assemble the test specimens and fabricate/produce the vacuum capsules

Test specimens they can be made by CERN (preferred) or be made on order by BNL (back-up option)

Irradiation-induced degradation

Irradiation-induced degradation

Irradiation-induced degradation

Irradiation-induced degradation

In DUE time we will discuss the additional Post-Irradiation analyses/studies on materials that are relevant to LHC collimation and which have been irradiated in the past and are available for further scrutiny and analysis

LHC LUMI - Simos-Bertarelli-Radaelli

Collimation Irradiation Damage Studies – Exploring other materials

PRIMARY- Copper (annealed) - Glidcop_15AL – Cu alloyed with .15% Al2O3

(axial cut and transverse cut)

SECONDARY- Super-Invar- Toyota “Gum Metal” - Graphite (IG-430 “isotropic”)

ALSO candidates under consideration

- Ti-6Al-4V - Tungsten- Tantalum- Low-Z alloy - AlBeMet

LHC-re

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LHC LUMI - Simos-Bertarelli-Radaelli

Irradiation effects on brazing or bonding:Up – design concepts for LHC collimationBelow – graphite-to-Ti and Copper-to-Titanium bonding showing serious interface degradation between graphite and Ti after irradiation at BNL