Overview of radiation damage studies and the RaDIATE Collaboration M. Calviani (CERN) P. Hurh (FNAL, RaDIATE program coordinator) R. Ferriere, M. Timmins, E. Fornasiere, A. Perillo-Marcone, D. Horvath, C. Torregrosa (CERN) + Makimura (J-PARC)

M. Calviani - RaDIATE & CERN application Introduction A new collaboration was started few years ago to cope with the lack of data concerning radiation damage in accelerator target environments Triggered by FNAL within the scope of the LBNF project and NuMI, i.e. for neutrino targets… … It took a more global scope when labs with different “requirements” joined the team (spallation, p-bar, beam windows, etc.) 1 February 2017 M. Calviani - RaDIATE & CERN application

Radiation Damage In Accelerator Target Environments RaDIATE Collaboration Radiation Damage In Accelerator Target Environments Broad aims are threefold: to generate new and useful materials data for application within the accelerator and fission/fusion communities to recruit and develop new scientific and engineering experts who can cross the boundaries between these communities to initiate and coordinate a continuing synergy between research in these communities, benefitting both proton accelerator applications in science and industry and carbon-free energy technologies radiate.fnal.gov Currently adding CERN and J-PARC to the MOU P. Hurh, FNAL

n p Radiation Damage Irradiation Source DPA rate (DPA/s) 1-14 MeV p 100+ MeV Irradiation Source DPA rate (DPA/s) He gas production (appm/DPA) Irradiation Temp (˚C) Mixed spectrum fission reactor 3 x 10-7 1 x 10-1 200-600 Fusion reactor 1 x 10-6 1 x 101 400-1000 High energy proton beam 6 x 10-3 1 x 103 100-800 14.9 DPA 23.3 DPA Add note that use of data from nuclear materials research is limited and should not be depended upon. Effects from low energy neutron irradiations do not equal effects from high energy proton irradiations. Table compares typical irradiation parameters. Cannot directly utilize data from nuclear materials studies! P. Hurh, FNAL 1 February 2017

High Energy Physics HPT Future Needs Exp/Facility Laboratory Time frame (yrs) “On the books”? Beam Power (kW) Comments ANU/NOvA FNAL 0.1 Y 700 Full power soon T2K J-PARC 2 750 Ramping Up! LBNF-1.2 MW 10 1,200 PIP-II enabled T2K Upgrade 10? ? 1,300 ~4 MW long-term? Next-Gen Nu Facility –2.5 MW 20? N 2,500? Mid-Term Next-Gen Nu Facility - 5 MW 30? 5,000? Longer-term BDF CERN 10 ? Y/N 500 High-Z target Future beam power and intensities present major challenges to reliable and efficient high power target facilities Other low power (but high intensity) target facilities will also be needed. Notably follow-on experiments to Mu2e/COMET, CERN AD-T, CERN n_TOF, TIDVG absorber etc… These are still challenging targets due to high-Z targets and small beam spots, but are not listed here. P. Hurh, FNAL + Marco

Targetry (and beam absorbers) scope Solid, liquid, rotating, rastered Other production devices: Collection optics (horns, solenoids) Monitors & instrumentation Beam windows Facility requirements: Remote handling Shielding and radiation transport Air handling Cooling systems Important applicability to CERN BIDs, such as production target (AD, n_TOF, BDF) and beam absorbers (TIDVGs, LHCTDE, FCCTDE etc.) which – already now – receives significant amount of beam 1 February 2017 M. Calviani - RaDIATE & CERN application 6

High power/intensity targetry challenges Material behavior Thermal “shock” response Radiation damage Highly non-linear thermo-mechanical simulation Targetry technologies Target system simulations (physics & reliability) Rapid heat removal Radiation protection Remote handling Radiation accelerated corrosion Manufacturing technologies Main focus within RaDIATE 1 February 2017 M. Calviani - RaDIATE & CERN application

Radiation Damage 0 DPA 3.2 DPA 14.9 DPA 23.3 DPA Displacements in crystal lattice (expressed as Displacements Per Atom, DPA) Embrittlement Creep Swelling Transmutation products H, He gas production can cause void formation and embrittlement (expressed as atomic parts per million per DPA, appm/DPA) Fracture toughness reduction Thermal/electrical conductivity reduction Coefficient of thermal expansion Modulus of Elasticity Fatigue response Dependent upon material condition and irradiation conditions (e.g. temp, dose rate) 0 DPA 3.2 DPA One notes that all the properties that are important for thermo-mechanical health of the target are affected by radiation damage. The dependence on irradiation temperature is due to annealing (or healing) the crystal structure is faster at higher temperatures. 14.9 DPA 23.3 DPA S. A. Malloy, et al., Journal of Nuclear Material, 2005. (LANSCE irradiations) P. Hurh, FNAL 1 February 2017

Examples of radiation damage D.L. Porter and F. A. Garner, J. Nuclear Materials, 159, p. 114 (1988) Factor of 10 reduction in conductivity at 0.02 DPA Void swelling in 316 Stainless steel tube (on right) exposed to reactor dose of 1.5E23 n/cm2 N. Maruyama and M. Harayama, “Neutron irradiation effect on … graphite materials,” Journal of Nuclear Materials, 195, 44-50 (1992) P. Hurh, FNAL 1 February 2017

The High Costs of High-Energy Radiation Damage Studies High energy, high fluence, large volume proton irradiations are needed to entirely replicate the HEP target environment and provide “bulk” samples for analysis High cost of irradiation “station” (4+ M$) Beam line and building not included in cost estimate High cost of irradiation beam time (0.5 M$ per 12 weeks) High cost of Post-Irradiation Examination (PIE) of activated samples (20+ k$ per sample) $$ $$ High-Energy irradiations including PIE are expensive and can take a very long time P. Hurh, FNAL 1 February 2017

Low Energy Ion Irradiations Instead? Fission and Fusion materials R&D community (e.g. University of Michigan Ion Beam Laboratory, MIBL ++ Europe as well) Positives: Low to zero activation (PIE in “normal” lab areas) Greatly accelerated damage rates (several DPA in a day) Significantly lower cost irradiations Negatives: Very shallow penetration (0-10 microns) Little gas production in samples Promising Solutions: Micro-mechanics may enable evaluation of critical properties Simultaneous implantation of He and H ions (triple-beam irradiation) But still need HE proton irradiations to correlate and validate techniques ¢¢ ¢¢ P. Hurh, FNAL 1 February 2017

Brief outlook on RaDIATE R&D 181 MeV p irradiation @ BNL’s BLIP facility 2017 BLIP Irradiation (see later) NuMI Be window PIE & future work (FNAL, Oxford) Helium implantation study at Surrey/Oxford In-beam thermal shock test of Be at CERN’s HiRadMat 2018 HRMT tests with BLIP irradiated materials NuMI target (NT-02) autopsy and graphite PIE ++ potential CNGS? Meso-scale fatigue testing (Oxford) Other complementary studies on C, graphite and Ti64 1 February 2017 M. Calviani - RaDIATE & CERN application

M. Calviani - RaDIATE & CERN application 2017 BLIP run Organized by the RaDIATE Collaboration Includes graphite at various temperature (up to 1000 C) Also Be, Ti alloys, Si, TZM, Al, CuCrZr, Ir, SiC-coated C Post-irradiation examination (2018) includes mechanical, thermal, microstructural and fatigue evaluation Participants: BNL, PNNL, FRIB, ESS, CERN, JPARC, STFC, Oxford, LANL 1 February 2017 M. Calviani - RaDIATE & CERN application

CERN application in the BLIP run Complement long-term radiation damage effects on materials used for targets (AD-target) and dump application Study of evolution of plastic deformation and fracture for irradiated materials at different temperatures for future targets and dump application Mean: Assess bulk mechanical properties of irradiated materials Materials: Iridium (AD-T), TZM (BDF + AD-T + ??), CuCrZr (TIDVG), Silicon (absorbers) Foreseen mechanical tests  4 point-bending tests Iridium, TZM, CuCrZr: 40 samples each (20x2x0.5 mm) Silicon: 40 samples (40x2x1 mm) 1 February 2017 M. Calviani - RaDIATE & CERN application

CERN application in the BLIP run Irradiation: proton beam between 120 MeV and 130 MeV and 150 mA for 2 weeks at BLIP facility at Brookhaven National Laboratory (BNL) Expected DPA over the two weeks run 0.32 in iridium 0.14 in TZM 0.18 in CuCrZr Reached irradiation temperature of ~900 °C 1 February 2017 M. Calviani - RaDIATE & CERN application

M. Calviani - RaDIATE & CERN application Objectives of the run Re-design of new irradiation capsule in order to accommodate samples, optimize e-beam welding and vacuum inside the capsule Irradiation foreseen 27th February Samples will be ready for analysis from mid-2018 after cool-down period Parallel tests at CERN for non-irradiated ones PIE: 4 point-bending mechanical tests at several temperatures (up to 1200°C) Tests to be realized at Pacific Northwest National Laboratory (PNNL) 1 February 2017 M. Calviani - RaDIATE & CERN application

Proposed configuration 1st Layer 2nd Layer 3rd Layer 4th Layer Total thick. Energy budget (MeV) Sample Sample + SS windows High-Z Capsule Ir 0.5 mm TZM CuCrZr Flexible graphite 0.1 mm 1.6 mm 7.19 9.23 Si Capsule SiC-Coated Graphite 1 mm Poly-Si 2 mm 5 mm 3.95 5.74 1 February 2017 M. Calviani - RaDIATE & CERN application 17

M. Calviani - RaDIATE & CERN application Sample geometry Same sample geometry for all four materials (Ir, TZM, CuCrZr, Si) Samples placed in a 40mm x 40mm square in the center of the capsule Only 4-point bending tests foreseen 5x @ RT 5x @ 500oC (TBC) 5x @ 800oC (TBC) 40 samples of dimensions 20 x 2 x 0.5 mm for Ir, TZM, CuCrZr 40 x 2 x 1 mm for Si All samples are engraved Could this geometry be used for measurement of thermal properties? 1 February 2017 M. Calviani - RaDIATE & CERN application 18

M. Calviani - RaDIATE & CERN application High-Z Capsule Capsule Flexible graphite Graphite filler CuCrZr samples TZM samples Cover Ir samples 0.3mm SS 0.3mm SS Cut view of High-Z capsule 1 February 2017 M. Calviani - RaDIATE & CERN application 19

Si Capsule Cut view of Si capsule Capsule Graphite filler SiC-coated graphite samples Si samples Si filler Si samples Flexible graphite Cover 0.3mm SS 0.3mm SS Cut view of Si capsule 1 February 2017 M. Calviani - RaDIATE & CERN application 20

SiC-coated Graphite Samples SiC coated graphite for application to muon targets Toyo Tanso Samples 0.76 mm graphite, density; 1.85 g/cc 0.12 mm SiC coating on both sides, density; 3.2 g/cc 3 samples (1 center + 2 periphery), effective density; 2.17 g/cc. Ibiden Samples 0.82 mm graphite, density; 1.75 g/cc 0.09 mm SiC coating on both sides, density; 3.2 g/cc 2 samples, effective density; 2.01 g/cc Filler: IG-430U (Toyo Tanso). density; 1.82g/cc 1 February 2017 M. Calviani - RaDIATE & CERN application 21 by S. Makimura

Thermal Analysis – Low Density Capsule Temperatures Thermal Expansions: Initial lateral gaps Samples-Fillers = 0.1 mm Initial lateral gap Fillers-SS capsule = 0.2 mm Max T Si samples: 216 ºC Max T Graph/SiC: Max T Sigraflex: 193 ºC Max T SS window: 71 ºC Remaining gap Graph/SiC –Filler: 94 um Remaining gap Si samples – Si Filler: 80 um Remaining Fillers– SS Capsule: 200 um (remains the same) Max HF SS window-Water: 28 W/cm2 T profile at the center of the capsule Graph/SiC samples Si samples Flexible (Sigraflex) graphite SS SS *Assumed TCC in Back-up slides 1 February 2017 M. Calviani - RaDIATE & CERN application 22

Thermal Analysis – Heavy Capsule Temperatures Thermal Expansions: Initial lateral gaps Samples-Fillers = 0.1 mm Initial lateral gap Fillers-SS capsule = 0.2 mm Max TZM samples: 610 ºC Max T Ir: 300 ºC Max T Flex Graph: 210 ºC Max T SS window: 116 ºC Remaining gap Heavy samples–Filler: 0 (contact, but displacement is absorbed by filler-SS gap) Remaining gap Filler–SS : Increases 20 um Max HF SS window-Water: 50 W/cm2 T profile at the center of the capsule Flex Graph Layer TZM samples Ir samples SS SS *Assumed TCC in Back-up slides 1 February 2017 M. Calviani - RaDIATE & CERN application 23

PIE @ PNNL – Mechanical properties I With the courtesy of D. Senor (PNNL) – ATS Seminar @CERN 1 February 2017 M. Calviani - RaDIATE & CERN application

PIE @ PNNL – Mechanical properties II With the courtesy of D. Senor (PNNL) – ATS Seminar @CERN 1 February 2017 M. Calviani - RaDIATE & CERN application

M. Calviani - RaDIATE & CERN application Conclusions The RaDIATE Collaboration has been active for the past ~3 years and is starting to produce results benefitting primarily HEP targetry global community (KEK, FNAL, CERN) Current and planned activities will also now directly benefit the Nuclear Physics and Spallation source communities (FRIB, ESS, CERN) Radiation damage and thermal shock are highest priority Fundamental limits of solid materials Mechanisms and conditions unique to accelerator target facilities Sustained efforts with multiple approaches Provides an important framework for information exchange and optimization of irradiation run as well as design 1 February 2017 M. Calviani - RaDIATE & CERN application