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Radiation Damage at High Energies: Data and Models

This meeting discusses radiation damage in materials under high energy irradiation and its effects on components and operational performance. Topics covered include melting, thermal shocks, insulation property deterioration, radiation damage to inorganic materials, superconducting magnet quench, single-event effects in electronics, and more.

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Radiation Damage at High Energies: Data and Models

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  1. Fermilab Accelerator Physics Center Radiation Damage at High Energies:Data and Theoretical Models(View from the Particle-Matter Interaction Side) Meeting of the EuCARD2 Collimation work package (WP11) GSI, Darmstadt, Germany December 4-5, 2014 Nikolai Mokhov

  2. Materials Under Irradiation • Depending on material, level of energy deposition density and its time structure, one can face a variety of effects in materials under irradiation. • Component damage (lifetime): • Melting, thermal shocks and quasi-instantaneous damage • Insulation property deterioration due to dose buildup • Radiation damage to inorganic materials due to atomic displacements and helium production. • Operational (performance): • Superconducting magnet quench • Single-event effects in electronics • Detector performance deterioration • Radioactivation, prompt dose and impact on environment Rad. Damage at High Energies - N. Mokhov

  3. Fermilab Pbar Target Stack Damage Short pulses with energy deposition density EDD in the range from 200 J/g (W), 600 J/g (Cu), ~1 kJ/g (Ni, Inconel) to ~15 kJ/g: thermal shocks resulting in fast ablation and slower structural changes, or melting. In Tevatron Run I, evidence of external target damage sustained when the rotation mechanism failed for several months. With target rotated properly, no damage to target although the outer Ti sleeve showed signs of swelling. Nickel was used first year of Run II. After several months of operation at 4.5×1012 ppp with sx =0.22 mm, sy = 0.16 mm, a region of damage about 2.5 mm wide developed on the target, with Ti jacket evaporated in that region and with a 15% drop in pbar yield. In Sep. 2002, switched to Inconel targets with their excellent high temperature tensile strength, although with relatively low thermal conductivity compared to Copper and Nickel. Rad. Damage at High Energies - N. Mokhov

  4. Run I Target Damage (1993-1994) Target disks are 0.95cm thick, with two 0.32cm Copper cooling disks between. 1993: pRe Xe Iodine isotopes in AP0 service building revealed flaw in the building ventilation system – fixed. 1994: Damage at the exit of Ni target chord because target rotation had failed for a period of months and only vertical motion was available. Also ejection of Ni bits led to a contamination incident. The entire vault wall was then resealed to ensure that air exiting the target vault could only do so through the filter system. Re Al Ni Cu Cu Rad. Damage at High Energies - N. Mokhov

  5. Run II Target 7 Damage (2007) Inconel-600 disks after 4 months of operation with total 2.65×1019 pot and RMS beam size sx~0.18mm, sy~0.22mm. A “consumable mode” to maximize pbar yield in the middle of Run II The observed was attributed to chemical oxidation of the damaged – by thermal shocks - target surface at the target chord beam exit. Because of tight limits established for vertical target positioning, the copper cooling disks emerged relatively undamaged, though distorted in some places. Rad. Damage at High Energies - N. Mokhov

  6. Target and Jacket Lifetime Switch to Inconel-600 extended the service life of each target from weeks to months (×6 for the entire stack) with practically no decrease in pbar yield. Radioactive particles from a damaged target were also a problem amplified by radioactive Ti bits from the damaged jacket. In Run II, the Titanium jacket has been replaced by a thin-walled cylinder of Graphite, and then by a 6.35-mm thick Be jacket, both being nearly transparent to primary beam and products of its interactions with the target. Rad. Damage at High Energies - N. Mokhov

  7. Tevatron Collimator Damage in 2003 Hole in 5-mm W 25-cm groove in SS J/g Detailed modeling of dynamics of beam loss (STRUCT), energy deposition (MARS) and time evolution over 1.6 ms of the tungsten collimator ablation, fully explained what happened. 980-GeV p-beam Rad. Damage at High Energies - N. Mokhov

  8. Hydrodynamics in Solid Materials Pulses with EDD >15 kJ/g: hydrodynamic regime. First done for the 300-ms, 400-MJ, 20-TeV proton beams for the SSC graphite beam dump, steel collimators and tunnel-surrounding Austin Chalk by SSC-LANL Collaboration (D. Wilson, …, N. Mokhov, PAC93, p. 3090). Combining MARS ED calculations at each time step for a fresh material state and MESA/SPHINX hydrodynamics codes. The hole was drilled at the 7 cm/ms penetration rate. Axial density of graphite beam dump in 60 ms after the spill start. Later, studies by N. Tahir et al with FLUKA+BIG2 codes for SPS & LHC These days we use MARS+FRONTIER. Tools are in hands Rad. Damage at High Energies - N. Mokhov

  9. Interaction of Radiation with Organic Materials A. Idesaki For given insulator and irradiation conditions radiation damage is proportional to energy deposition (dose) Rad. Damage at High Energies - N. Mokhov

  10. Energy Deposition Modeling:Highly Accurate with Electronic and NIEL included MARS15 In majority of real-life complex applications, FLUKA and MARS15 energy deposition results coincide within a few % and agree with data. Rad. Damage at High Energies - N. Mokhov

  11. DPA The dominant mechanism of structural damage of inorganic materials is displacement of atoms from their equilibrium position in a crystalline lattice due to irradiation with formation of interstitial atoms and vacancies in the lattice. Resulting deterioration of material critical properties is characterized as a function of displacements per atom (DPA). DPA is a strong function of projectile type, energy and charge as well as material properties including its temperature. OK at t= 0 followed by, e.g., kinetic Monte Carlo up to 104 s. Rad. Damage at High Energies - N. Mokhov

  12. DPA Model in MARS15:Microscopic Modeling All products of elastic and inelastic nuclear interactions as well as Coulomb elastic scattering (NIEL) of transported charged particles (hadrons, electrons, muons and heavy ions) from 1 keV to 10 TeV contribute to DPA in this model. For electromagnetic elastic (Coulomb) scattering, Rutherford cross section with Mott corrections and nuclear form factors are used. NRT damage function: Td is displacement energy (~40 eV) Ed is damage energy (~keV) Energy-dependent displacement efficiency k(T) by Stoller/Smirnov: Rad. Damage at High Energies - N. Mokhov

  13. Medium- and Low-E Neutron DPA Model in MARS15and Optional Correction at Cryo Temperatures T = 4-6 K Al For neutrons from 10-5 eV to 150 MeV: NJOY99+ENDF-VII database, for 393 nuclides. At T=4-6K, optional correction for experimental defect production efficiency η (Broeders, Konobeev, 2004), where η is a ratio of a number of single interstitial atom vacancy pairs (Frenkel pairs) produced in a material to the number of defects calculated using NRT model Rad. Damage at High Energies - N. Mokhov

  14. DPA Code Intercomparision p + Pb 2013 FLUKA, MARS15 and PHITS intercomparison for Mu2e SC coil hottest spot: 15% agreement M.J. Boschini et al., “Nuclear and Non-Ionizing Energy-Loss for Coulomb Scattered Particles from Low Energy up to Relativistic Regime in Space Radiation Environment”, arXiv:1011.4822v6 [physics.space-ph] 10 Jan 2011 Rad. Damage at High Energies - N. Mokhov

  15. MARS15 vs Jun Modeling I. Jun, “Electron Nonionizing Energy Loss for Device Applications”, IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 56, NO. 6, DECEMBER 2009 p + C p + Si p + Cu • Minimal proton transport cutoff energy in MARS is 1 keV Rad. Damage at High Energies - N. Mokhov

  16. Electron irradiations create single Frenkel defects (point defects of interstitials and vacancies) Low-energy protons and light ions create similar defects as electron irradiations Heavy ions and neutrons produce cascade displacement damage Fusion neutrons create significant subcascades with very high energy PKAs Defect Production vs Irradiation Type Damage correlation by different types of irradiation should consider production of defects in single point defects and defect clusters Rad. Damage at High Energies - N. Mokhov

  17. Code Capabilities in DPA Modeling Electron and heavy-ion beams: in most cases, DPA is dominated by electronic energy loss of a primary beam; FLUKA/MARS/PHITS/SRIM are doing quite well here. Neutrons at E < 150 MeV: Point defects; ENDF/NJOY damage x-section libraries & processing – OK. Protons: Medium energies: (1) and (2) – OK. High-energy hadrons and heavy ions: nuclear interaction model dependent; most difficult; mixed (1) and (2) regimes; FLUKA/MARS can be OK even at very high energies. Rad. Damage at High Energies - N. Mokhov

  18. Hydrogen and Helium Gas Production At accelerators, radiation damage to structural materials is amplified by increased hydrogen and helium gas production for high-energy beams. In SNS-type beam windows, the ratio of He/atom to DPA is about 500 of that in fission reactors. These gases can lead to grain boundary embrittlement and accelerated swelling. In modern codes at intermediate energies, uncertainties on production of hydrogen are ~20%. For helium these could be up to 50%. C. Broeders, A. Konobeyev, FZKA 7197 (2006) D. Hilscher et al., J.Nucl.Mat, 296(2001)83 Rad. Damage at High Energies - N. Mokhov

  19. Nick Simos’ Rad.Damage Studies at BLIP with 100-200 MeV protons 2-D carbon Graphite 3-D carbon Glidcop in both axial and transverse directionssees 40% reduction at ~1 dpa.3-D CC (~ 0.2 dpa) conductivity reduces by 3.2.2-D CC (~0.2 dpa) measured under irradiated conditions (to be compared with company data).Graphite (~0.2 dpa) conductivity reduces by 6. Rad. Damage at High Energies - N. Mokhov

  20. BLIP Data and Possible Explanations • Observation: • In proton irradiation, a threshold exists on carbon composites and graphite at ~0.2 DPA, lower than expected from reactor data (although there were indications of such a level for CTE in reactor data). • Possible explanations: • Contribution of Coulomb elastic scattering ~Zp2, becomes important (dominant in some instances) for charged particle irradiation. • DPA in BLIP tests was estimated with earlier versions of MCNPX known to underestimate (neglect) contribution of this process. • Helium gas production adds, becoming increasingly important at high energies. • Graphite, wrt some properties, is indeed less radiation-resistant than expected. Rad. Damage at High Energies - N. Mokhov

  21. FNAL Neutrino Yield and Target Degradation • Observation: • Neutrino yield has degraded by up to 10% after exposure of the target with 6e20 protons. • Explanation: Radiation damage of the target material in the shower maximum region (z ~ 10-15 cm, r < 1-2 mm). • Possible mechanisms: • Void creation due to DPA (a simple model tried by two groups). • Helium bubble production, quite substantial at 120 GeV. Trapped bubbles and helium pressure would reduce target density in the above region. • Graphite amorphization: r = 1.8 gcc porous carbon r ~ 1.5 gcc (according to M. Tomut). • Transmutation of carbon nuclei. Rad. Damage at High Energies - N. Mokhov

  22. Link of Calculated Quantities to Observable Changes • Link of calculated quantities (DPA, dose, fluence etc.) to observable changes in critical properties of materials in theoretical/modeling studies remains to be a dream • Promising experiments • Low-energy heavy ions at GSI in very clean conditions (although, surface vs bulk damage?) • Studies at BNL: 200-MeV protons and fast neutrons at BLIP, and 28-MeV protons at TANDEM (BNL) • Kurchatov institute experiments • Neutrons at Kyoto reactor at room and cryo temperatures (remember the lower dose rate) • Counting DPA in Si-detectors • Measuring gas production • Promising developments: kinetic Monte-Carlo • Meanwhile, rely on phenomenology and correlations Rad. Damage at High Energies - N. Mokhov

  23. Damage Correlation Parameters • Irradiation particle, e.g. protons vs. neutrons • Energy spectra • Flux or dose rate (dpa/s) • Fluence or dose (dpa) • Irradiation temperature • Transmutation (e.g. He, H) • Pulsed irradiation vs. continuous irradiation Rad. Damage at High Energies - N. Mokhov

  24. Correlations Observed at High Energies • For the given insulator, environment and irradiation conditions, radiation damage is proportional to the energy deposition (dose) in the same (microscopic) region. • In inorganic materials, DPA is proportional to • dE/dx for heavy ions in thin targets • Energy deposition in thin (in terms of lin) targets • Hadron (mainly neutron) fluence in extended targets • Hydrogen/Helium production rate grows with energy up to ~10 GeV and is proportional to hadron fluence. Rad. Damage at High Energies - N. Mokhov

  25. DPA, Helium and Energy Deposition Distributionsin 1-m Graphite for 120-GeV Protons Similar in this particular case (high energy, low-Z, small r), not in general Rad. Damage at High Energies - N. Mokhov

  26. 7×7 TeV pp-collisions FLUKA and MARS15 agree within 20% DPA follows neutron fluence profile in SC coils of IP1/5 inner triplet Rad. Damage at High Energies - N. Mokhov

  27. Recent Developments Corrections to the reference NRT model: BCA, MD, BCA-MD (IOTA code at KIT) and various forms of defect production efficiency. Most recently by Nordlund: Kinetic Monte Carlo (up to 104 s cf to ns in MD): Individual defects, clusters, impurities, annealing Complete simulations: particle interaction and transport codes coupled to BCA+MD(+KMC) Rad. Damage at High Energies - N. Mokhov

  28. M Rad. Damage at High Energies - N. Mokhov

  29. M Rad. Damage at High Energies - N. Mokhov

  30. Gas Production: p, d, t, 3He and 4He Nuclear models implemented in popular computer codes predict gas production cross-section with varying degrees of success depending on theenergy of projectiles. The use of cross-sections evaluated using nuclear model calculations and measured data is one of the most reliable and flexible approach for advanced calculation of gas production rate, certainly at intermediate energies. KIT: 278 targets from 7Li to 209Bi; incident proton energies: 62, 90, 150, 600, 800, 1200 MeV Rad. Damage at High Energies - N. Mokhov

  31. Quantify Material Performance via FOM With added damage limit factor Beam-Materials Interactions - N. Mokhov

  32. Desperate Needs for Data • Tolerable limits on maximum steady-state temperature of Al-6026 with respect to creep, swelling and fatigue without radiation and for pulsed irradiation and pulsed current; starting from room temperature: focusing horns, beam windows and beam dumps, first of all in neutrino experiments. • Irradiation limits on graphite, graphite components, MoGR, CuCD etc. for variety of beams and irradiation conditions: targets, collimators, beam dumps (LHC in the first place) • RRR degradation of Al and Cu at T ~ 4 K, including annealing: large superconducting solenoids (Mu2e, COMET etc.) and collider SC magnets. • Correlation of data from reactors and proton, heavy ion and electron beams for the same or similar conditions. • These are the multi-million dollar questions. Rad. Damage at High Energies - N. Mokhov

  33. Summary (1) • Radiation damage by high energy protons includes displacement cascades and transmutation production of helium and hydrogen and other impurities. • DPA is the parameter commonly used to correlate displacement damage. However, the extent of radiation damage cannot be fully characterized by a single parameter. • Damage correlation between different types of irradiations should consider: • Primary recoil energy spectra • Displacement dose rate, DPA/s • Transmutation production rates, He/DPA and H/DPA • Kinetics of irradiation-induced defect production and accumulation behavior due to pulsed irradiation • Further quantification is needed on annealedvs non-annealed defects. • Develop an approach to accurate calculation of DPA induced by low-energy neutrons in compounds. Rad. Damage at High Energies - N. Mokhov

  34. Summary (2) Radiation damage by high-energy beams is more intense (for the same fluence) due to Coulomb elastic scattering ~Zp2; codes which include this process, nuclear interactions, and same DPA model parameters agree quite well; radiation damage at high energies is amplified by intense helium gas production. Move from occasional comparisons of calculated radiation-damage related quantities to a comprehensive code intercomparison with “standardized” DPA models and benchmarking at well defined irradiation conditions including temperature, dose rate, H2/He gas production, etc. The correlation factors - DPA/D, DPA/Fn, NHe/DPA – need to be generated, compared and related to reactor data. Further weight experimental possibilities and promising theoretical and simulation developments towards link of DPA to changes in material critical properties. Rad. Damage at High Energies - N. Mokhov

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