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Vanlig materia består huvudsakligen av protoner, neutroner och elektroner. Genom att kollidera partiklar med varandra vid höga energier kan man även skapa antiprotoner, antineutroner och positroner. Dessa så kallade antipartiklar har samma egenskaper som sina vanliga motsvarigheter fast med motsatt elektrisk laddning. Eftersom universum behandlar partiklar och antipartiklar på ett liknande sätt kan man fråga sig varför det finns mer materia än antimateria i universum. I skrivande stund har vetenskapen inget entydigt svar på denna fråga. Av någon anledning har universum utvecklat en preferens för materia framför antimateria, ett fynd som inte kan förklaras av den nuvarande formuleringen av standardmodellen för partikelfysik. HIBEAM-experimentet kan vara en viktig pusselbit i strävan att lösa detta mysterium. Experimentet kommer att söka efter spontana oscillationer mellan neutroner och antineutroner. Det kommer också att leta efter oscillationer till sterila neutroner, en ännu oupptäckt partikel som, om den finns, interagerar mycket svagt med vanlig materia. Oscillationsprocessen lär vara särskilt trolig för fria neutroner som inte är bundna i atomkärnor. För att maximera sannolikheten för oscillationer behöver vi därför studera ett stort antal fritt flygande neutroner. Lyckligtvis kommer European Spallation Source (ESS), belägen i Lund, att vara en av de mest kraftfulla neutronkällorna i världen. Genom att studera neutronerna när de rör sig i ett långt vakuumrör och placera neutron- och/eller antineutrondetektorer i änden av röret går det att avgöra om en oscillation har skett. I detta examensarbete har en geometrisk modell av ett nytt ESS-strålrör utvecklats. Modellen har använts för att simulera stråldosen som genereras av neutronerna och fotonerna i strålröret. Detta är nödvändigt för att avgöra hur mycket strålskydd som behövs för att följa relevanta hälso- och säkerhetsföreskrifter. Simuleringarna genomförs med hjälp av Monte Carlo-simuleringsprogram, där slump, Ordinary matter mainly consists of protons, neutrons and electrons. By colliding particles with each other at high energies, you can also create antiprotons, antineutrons and positrons. These so-called antiparticles have the same properties as their normal counterparts but with the opposite electrical charge. Since the universe treats particles and antiparticles in a similar way, one might ask why there is more matter than antimatter in the Universe. At the time of writing, science has no clear answer to this question. For some reason, the Universe has developed a preference for matter over antimatter, a finding that cannot be explained by the current formulation of the Standard Model of particle physics. The HIBEAM experiment may be an important puzzle piece in the quest to solve this mystery. The experiment will search for spontaneous oscillations between neutrons and antineutrons. It will also search for oscillations into sterile neutrons, a yet undiscovered particle which, if it exists, interacts very weakly with ordinary matter. The neutron oscillation process is thought to be particularly likely for free neutrons that are not bound in nuclei. To maximise the probability of transitions, we therefore need to study a large number of free-flying neutrons. Fortunately, the European Spallation Source (ESS), situated in Lund, Sweden, will be one of the most powerful neutron sources in the world. By studying the neutrons as they propagate in a long vacuum pipe and placing neutron and/or antineutron detectors at the end of the pipe, it is possible to determine whether oscillation has taken place. Within this thesis, a geometrical model of a new ESS beamline has been developed. The model has been used to simulate the radiation dose generated by the neutrons and photons in the beamline. This is necessary to determine how much shielding is needed to abide by relevant health and safety regulations. The simulations are performed using Monte Carlo simulation programs, where

Analysis of neutron distribution was carried out for two elongated targets. The targets have cylindrical shape and are made of lead and carbon, respectively. The dimensions are approximately one meter in length and 19 cm in diameter. The targets were irradiated with 660 MeV proton beam at Phasotron accelerator at the Joint Institute for Nuclear Research. The total number of protons was 2.35(18)E15 for the experiment with carbon target and the total number of particles at the second experiment was 2.32(19)E15. The produced neutron field was monitored by cobalt threshold activation detectors at various positions. The activation detectors were measured by means of gamma spectroscopy using HPGe detectors. Reaction rates of different radionuclides produced in the activation detectors were determined and the results from both experiments were compared. The ratios were calculated for 7 reactions produced in cobalt detectors. The ratio of the reaction rates shows that the number of residual nuclei with higher threshold energies is higher for experiment with carbon target than for the experiment with the lead target.

Solar neutrinos pass through the Earth's surface with a flux on the order of $10^{11} /\mbox{cm}^2/s$. The Super-Kamiokande (SK) searches for neutrinos from the sun with an energy above 4.0 MeV. Neutrinos rarely interact with matter, and removing backgrounds that would otherwise overwhelm the signal is imperative. SK observes about 2 muons a second at its depth of 2700m water equivalent, and a fraction of these muons shower within the detector with a possibility to create radioactive isotopes (spallation) which live from milliseconds to tens of seconds. Radioactive isotopes from any source are by far the largest source of background in the solar neutrino energy region observed in SK, and spallation is the dominant background to neutrino interactions between 6 and 20 MeV. Spallation in SK is mostly caused by neutrons and pions interacting with the Oxygen nucleus. Recently, new techniques involving identifying neutron in the showers after muons and effective tagging of multiple spallation, along with improvements and additions to former spallation tagging methods have reduced deadtime by $\sim$55\% ($\sim$45\%) where neutron data is available (unavailable). This increases measured solar neutrino signal by 12\% and reduces relative statistical error by 6.6\% for the entire SK-IV solar neutrino sample.

Analysis of neutron distribution was carried out for two elongated targets. The targets have cylindrical shape and are made of lead and carbon, respectively. The dimensions are approximately one meter in length and 19 cm in diameter. The targets were irradiated with 660 MeV proton beam at Phasotron accelerator at the Joint Institute for Nuclear Research. The total number of protons was 2.35(18)E15 for the experiment with carbon target and the total number of particles at the second experiment was 2.32(19)E15. The produced neutron field was monitored by cobalt threshold activation detectors at various positions. The activation detectors were measured by means of gamma spectroscopy using HPGe detectors. Reaction rates of different radionuclides produced in the activation detectors were determined and the results from both experiments were compared. The ratios were calculated for 7 reactions produced in cobalt detectors. The ratio of the reaction rates shows that the number of residual nuclei with higher threshold energies is higher for experiment with carbon target than for the experiment with the lead target.

Analysis of neutron distribution was carried out for two elongated targets. The targets have cylindrical shape and are made of lead and carbon, respectively. The dimensions are approximately one meter in length and 19 cm in diameter. The targets were irradiated with 660 MeV proton beam at Phasotron accelerator at the Joint Institute for Nuclear Research. The total number of protons was 2.35(18)E15 for the experiment with carbon target and the total number of particles at the second experiment was 2.32(19)E15. The produced neutron field was monitored by cobalt threshold activation detectors at various positions. The activation detectors were measured by means of gamma spectroscopy using HPGe detectors. Reaction rates of different radionuclides produced in the activation detectors were determined and the results from both experiments were compared. The ratios were calculated for 7 reactions produced in cobalt detectors. The ratio of the reaction rates shows that the number of residual nuclei with higher threshold energies is higher for experiment with carbon target than for the experiment with the lead target.

TARDOCCHI, MARCO, GORINI, GIUSEPPE, open, As the increasing interest in MeV range neutrons for applied physics studies, the development of dedicated fast neutron-based instruments, which have the capabilities to deal with complex background and to measure high counting rate (MHz), is demanded. This thesis presents the development both on a fast response scintillation detector that has been developed as a neutron emission monitor for deuterium beam diagnostics on large current negative beam test facility (like ELISE or SPIDER), and on the design and test of Telescope Proton Recoil (TPR) neutron spectrometers dedicated for neutron spectrum measurements on the fast neutron beam line ChipIr at ISIS. These instruments have been studied at accelerator-based platforms, tested at the ISIS spallation neutron source, as well as been applied in dedicated experiments on ELISE. Development of the two types of fast neutron-based instruments in applications to fusion and spallation neutron sources are presented in the following two parts: (1). Measurement of the deuterium beam-target neutron emission that occurs when the deuterium beam penetrates in the metallic dump of the NBI (neutral beam injector) prototype has been proposed as a means of diagnostics on beam homogeneity at SPIDER and MITICA. In order to present the deuterium beam profile by measuring the produced neutrons from the DD reactions between the deuterium beam and deuterons previously implanted in the beam dump, a relative model should be built to predict the neutron emission based on understanding the process of deuterium implantation in dump, and to aid the CNESM detection system which is based on the GEM technique for beam profile diagnostics in SPIDER. To this end, a calibrated EJ301 liquid scintillation detector has been developed and used on ELISE to measure the time trace of neutron emission and to benchmark calculations based on the Local Mixing Model (LMM), which has been applied to describe the deuterium implantation in the dump. The scintillation, As the increasing interest in MeV range neutrons for applied physics studies, the development of dedicated fast neutron-based instruments, which have the capabilities to deal with complex background and to measure high counting rate (MHz), is demanded. This thesis presents the development both on a fast response scintillation detector that has been developed as a neutron emission monitor for deuterium beam diagnostics on large current negative beam test facility (like ELISE or SPIDER), and on the design and test of Telescope Proton Recoil (TPR) neutron spectrometers dedicated for neutron spectrum measurements on the fast neutron beam line ChipIr at ISIS. These instruments have been studied at accelerator-based platforms, tested at the ISIS spallation neutron source, as well as been applied in dedicated experiments on ELISE. Development of the two types of fast neutron-based instruments in applications to fusion and spallation neutron sources are presented in the following two parts: (1). Measurement of the deuterium beam-target neutron emission that occurs when the deuterium beam penetrates in the metallic dump of the NBI (neutral beam injector) prototype has been proposed as a means of diagnostics on beam homogeneity at SPIDER and MITICA. In order to present the deuterium beam profile by measuring the produced neutrons from the DD reactions between the deuterium beam and deuterons previously implanted in the beam dump, a relative model should be built to predict the neutron emission based on understanding the process of deuterium implantation in dump, and to aid the CNESM detection system which is based on the GEM technique for beam profile diagnostics in SPIDER. To this end, a calibrated EJ301 liquid scintillation detector has been developed and used on ELISE to measure the time trace of neutron emission and to benchmark calculations based on the Local Mixing Model (LMM), which has been applied to describe the deuterium implantation in the dump. The scintillation, No, embargoed_20220113, Feng, S

As the increasing interest in MeV range neutrons for applied physics studies, the development of dedicated fast neutron-based instruments, which have the capabilities to deal with complex background and to measure high counting rate (MHz), is demanded. This thesis presents the development both on a fast response scintillation detector that has been developed as a neutron emission monitor for deuterium beam diagnostics on large current negative beam test facility (like ELISE or SPIDER), and on the design and test of Telescope Proton Recoil (TPR) neutron spectrometers dedicated for neutron spectrum measurements on the fast neutron beam line ChipIr at ISIS. These instruments have been studied at accelerator-based platforms, tested at the ISIS spallation neutron source, as well as been applied in dedicated experiments on ELISE. Development of the two types of fast neutron-based instruments in applications to fusion and spallation neutron sources are presented in the following two parts: (1). Measurement of the deuterium beam-target neutron emission that occurs when the deuterium beam penetrates in the metallic dump of the NBI (neutral beam injector) prototype has been proposed as a means of diagnostics on beam homogeneity at SPIDER and MITICA. In order to present the deuterium beam profile by measuring the produced neutrons from the DD reactions between the deuterium beam and deuterons previously implanted in the beam dump, a relative model should be built to predict the neutron emission based on understanding the process of deuterium implantation in dump, and to aid the CNESM detection system which is based on the GEM technique for beam profile diagnostics in SPIDER. To this end, a calibrated EJ301 liquid scintillation detector has been developed and used on ELISE to measure the time trace of neutron emission and to benchmark calculations based on the Local Mixing Model (LMM), which has been applied to describe the deuterium implantation in the dump. The scintillation, As the increasing interest in MeV range neutrons for applied physics studies, the development of dedicated fast neutron-based instruments, which have the capabilities to deal with complex background and to measure high counting rate (MHz), is demanded. This thesis presents the development both on a fast response scintillation detector that has been developed as a neutron emission monitor for deuterium beam diagnostics on large current negative beam test facility (like ELISE or SPIDER), and on the design and test of Telescope Proton Recoil (TPR) neutron spectrometers dedicated for neutron spectrum measurements on the fast neutron beam line ChipIr at ISIS. These instruments have been studied at accelerator-based platforms, tested at the ISIS spallation neutron source, as well as been applied in dedicated experiments on ELISE. Development of the two types of fast neutron-based instruments in applications to fusion and spallation neutron sources are presented in the following two parts: (1). Measurement of the deuterium beam-target neutron emission that occurs when the deuterium beam penetrates in the metallic dump of the NBI (neutral beam injector) prototype has been proposed as a means of diagnostics on beam homogeneity at SPIDER and MITICA. In order to present the deuterium beam profile by measuring the produced neutrons from the DD reactions between the deuterium beam and deuterons previously implanted in the beam dump, a relative model should be built to predict the neutron emission based on understanding the process of deuterium implantation in dump, and to aid the CNESM detection system which is based on the GEM technique for beam profile diagnostics in SPIDER. To this end, a calibrated EJ301 liquid scintillation detector has been developed and used on ELISE to measure the time trace of neutron emission and to benchmark calculations based on the Local Mixing Model (LMM), which has been applied to describe the deuterium implantation in the dump. The scintillation

The European Spallation Source (ESS), which is currently under construction in Lund, will use pure tungsten as the spallation neutron target. The tungsten will be irradiated by a 2 GeV proton beam, pulsed at a repetition rate of 14 Hz. Each pulse will deposit 357 kJ in the tungsten causing an instantaneous temperature rise of approximately 100 °C, during the 2.86 ms pulse duration. The target is wheel-shaped, 2.6 m in diameter, and will be rotating at 0.39 Hz to distribute the proton beam loads. The tungsten target consists of nearly 7000 bricks with dimensions 80×30×10 mm3. The bricks are separated by 2 mm wide cooling channels in which helium gas flows at a rate of 2.85 kg/s. The proton beam will be more powerful than the beam used at any other existing neutron spallation facility. Thanks to the high beam power and innovative moderator design, ESS will become the brightest neutron source in the world. However, designing the target is challenging, as its structure should withstand loads from the high beam power. The high intensity proton beam will not only cause cyclic thermo-mechanical loading of the tungsten, but also irradiation damage in the form of displacements of atoms in the microstructure, and production of a wide range of radioactive isotopes such as gaseous transmutation elements, and a significant fraction of solid transmutation elements, which will alter the thermal and mechanical properties of tungsten. Using such a powerful beam requires an optimal design of the target and a good understanding of the complex physical, mechanical, and thermal changes occurring in irradiated tungsten. It is also important to identify and mitigate potential issues and accidental scenarios during operation of the ESS target. The present work aims to characterise thermal and mechanical properties of high-energy proton and spallation neutron irradiated pure tungsten, for the use as a spallation target material. The work includes studies on fatigue properties of unirradiate

The purpose of this project was to develop a better understanding of the re- sponse of a pixelated thermal-neutron detector, which will be used as a thermal- neutron detector at one of the beam lines at the European Spallation Source in Lund, Sweden. The detector consists of a thin Lithium6-glass scintillator, a multi-anode photomultiplier tube and associated read-out electronics. Initial characterizations of the response to laser light and a collimated alpha-particle beam were performed in collaboration with the Department of Nuclear Physics at the University of Glasgow. The response of the prototype to the laser light was demonstrated to be reproducible. The absolute gain for each pixel provided by the manufacturer for the multi-anode photomultiplier tube was not repro- ducible. For the first time ever, the response of the prototype to a collimated alpha-particle beam was determined. Pixel-to-pixel gain variations were gain corrected using both the measured laser correction matrix and the data sheet from the manufacturer. Qualitative similarities between the results using the two calibration methods clearly exist. Further study is warranted., Neutrons are small particles with no charge. Together with protons, they are what makes up the nuclei of the atoms. The fact that neutrons have no charge makes them excellent to use as probes in material science. This is what researcher are planning to do at the European Spallation Source (ESS) which is currently being built in Lund, Sweden and is expected to be finished in 2023. This project is about how you detect these neutrons after they have interacted with a sample.

1. INTRODUCTION. The neutron time-of-flight facility at CERN is a source of high flux of neutrons obtained by the spallation process of 20 GeV/c protons from the CERN Proton Synchrotron (PS) onto a high purity (99.99 %) lead target. A first facility, operational since 2001, was based on a non-monolithic lead target, an open cooling circuit of demineralized water and absence of control on the water chemistry. It suffered severe corrosion and extensive deformation of the central part of the target as a consequence of the local energy deposition and insufficient cooling. Excessive temperature at the beam interaction point induced creep in the lead blocks and activated severe pitting corrosion. After a few years of operation, the facility required a complete upgrade. The new facility, running since its commissioning in November 2008, consists of a monolithic lead cylindrical target with a diameter of 0.6 m, a height of 0.4 m and a total weight of 1.3 tons (Fig. 1). The target is cooled by a pressurized water cooling system, including an all-welded aluminium alloy vessel and a cooling circuit with monitored and controlled oxygen content and conductivity of the demineralized water used as coolant. The value of oxygen and conductivity is continuously monitored. Due to the presence of high electric fields, easiness of maintenance and prevention of corrosion, demineralized water is widely used at CERN in cooling circuits of particle physics detectors and accelerator magnets. During Long Shutdown (LS2) a third spallation target (target #3) will be installed in the facility, in order to substitute the present target which will have reached its end of life. The target is presently under design. Various materials are being investigated for both the core and the contact part with the cooling wáter. In the framework of the target upgrade activities, a new water erosion/corrosion test bench is required, in order to evaluate the compatibility of various materials in the n_TOF target, 1. INTRODUCCIÓN La instalación de neutron time-of-flighten (n_TOF) del CERN es una fuente de alto flujo de neutrones obtenida por el proceso de espalación de protones a 20 GeV/c procedentes del Proton Synchrotron (PS) del CERN sobre un Target de plomo de alta pureza (99,99%). Una primera instalación, operativa desde 2001, se basó en un Target de plomo no monolítico, un circuito de refrigeración abierto de agua desmineralizada y ausencia de control sobre la química del agua. Sufría una corrosión severa y una deformación extensa de la parte central del Target como consecuencia de la deposición de energía local y enfriamiento insuficiente. La temperatura excesiva en el punto de interacción del haz indujo la fluencia en los bloques de plomo y activó una severa corrosión por picaduras. Después de unos años de operación, la instalación requirió una actualización completa. La nueva instalación, que funciona desde su puesta en servicio en noviembre de 2008, consiste en un Target cilíndrico monolítico de plomo con un diámetro de 0,6 m, una altura de 0,4 m y un peso total de 1,3 toneladas (Figura 1). El Target es enfriado por un sistema de refrigeración de agua a presión, incluyendo un recipiente de aleación de aluminio completamente soldado, un circuito de enfriamiento con contenido de oxígeno monitorizado y controlado y conductividad del agua desmineralizada usada como refrigerante. El valor del oxígeno y la conductividad se monitoriza continuamente. Debido a la presencia de campos eléctricos de elevada intensidad, facilidad de mantenimiento y prevención de la corrosión, el agua desmineralizada es ampliamente utilizada en el CERN en circuitos de refrigeración de detectores de física de partículas y de imanes aceleradores. Durante la próxima parada larga (LS2) se instalará un tercer Target de espalación (objetivo # 3) en la instalación, con el fin de sustituir al objetivo actual que habrá alcanzado su fin de vida útil. El objetivo está actualmente bajo diseño. Se están inves, [CA] La instal·lació de neutrons de temps de vol (n_TOF) al CERN és una font d'alt flux de neutrons obtinguda pel procés d’espal·lació de 20 GeV/c de protons sobre un objectiu de plom d'alta puresa (99,99 %). El 2008, la instal·lació va patir una corrosió severa després de pocs anys d'operació, aquesta va ser completament millorada. Inclou ara un recipient d'aliatge d'alumini i un circuit de refrigeració amb contingut d'oxigen i conductivitat de l'aigua desmineralitzada, utilitzada com a refrigerant i moderador, controlats. Durant la parada llarga (LS2) s'instal·larà un tercer objectiu de espal·lació (objectiu #3) en la instal·lació, per substituir l'objectiu actual que hi haurà arribat al seu fi de vida útil. L'objectiu està actualment sota disseny. S'estan investigant diversos materials per al nucli i la part en contacte amb l'aigua del sistema de refrigeració. En el marc de les activitats de millora d'objectius, es requereix un nou banc de proves d'erosió / corrosió, per tal d'avaluar la compatibilitat de diversos materials en el règim de l'objectiu n_TOF. El nou banc de proves està destinat per a ser capaç de realitzar proves d'erosió i corrosió, i verificar els canvis dels materials per validar el disseny del nou objectiu. Aquest banc de proves ha estat dissenyat d'una manera que serà versàtil i adaptable a diferents tipus de proves i objectius en el futur. La idea és que el disseny pot modificar variables com ara el flux del circuit, la temperatura, la conductivitat del fluid i la pressió per a diferents proves amb bons valors de lectura i registre. El projecte del banc de proves comprèn del disseny conceptual al disseny detallat i la fabricació del dispositiu. Aquest treball s'ha dut a terme en col·laboració amb diversos grups del CERN, involucrats en l'especificació tècnica, anàlisi, disseny, fabricació i seguretat.

At European Spallation Source ERIC, 2 GeV proton bunches will be accelerated towards a tungsten target where spallation will occur, producing a wide neutron energy spectrum. Despite the shielding and moderators in place to stop and/or reduce their energy, a significant portion of the most energetic neutrons, called prompt neutrons, might still reach the sample position of a neutron-scattering instrument. It has been previously shown that these prompt neutrons contribute to a degradation of the signal-to-noise ratio of the detectors. Clearly, a tool for identifying sources of fast-neutron background would be very valuable. The design goals of the envisioned Portable Fast-Neutron Diagnostic Detector include portability, durability, fast response and the ability for performing self-triggering time-of-flight measurements complete with tracking to localize fast-neutron sources. Within the context of this thesis, the detector system was conceptualized, designed and a prototype assembled. Testing was carried out with a plutonium/beryllium source and a industry-standard liquid scintillator detector to define a tagged fast-neutron beam (2.8-6.3 MeV). It was shown that the neutron response is energy dependent and improves at lower energies. Fast-neutron tracking capabilities of the detector were demonstrated., Spallations anläggningar är ämnade för produktion och forskning med fria neutroner. Ett problem uppstår för dessa anläggningar efter att högenergetiska neutroner skapas via en så kallad spallation. Högenergetiska neutroner är problematiska att hålla udner kontroll. På grund av deras höga energi kan dessa neutronerna ``rymma'' och orsaka kärnreaktioner som bidrar till en försvagad signal-upplösningen hos forsknings-instrumenten på dessa anläggningarna. Detta projekt behandlar utvecklingen av ett diagnos instrument som kan titta på just dessa högenergetiska neutroner. Instrumentet kan sedan användas av spallations anläggningarna för att kartlägga sina snabba neutroner som rymt.

This paper describes the influence of initial conditions for spallation particles flying in polymer ablation arcs on dynamics and evaporation of the polymer spallation particles using the numerical model. Through our previous experiments, we had found micro-sized `spallation particles' ejected from polyamide materials by thermal plasma contact. To obtain the dynamics of spallation particles in polymer ablation arcs, we have developed a numerical model on dynamics of spallation particles flying in the polymer ablated arcs. The influence of pressure inside the polymer ablated arc, the initial particle diameter and the initial velocity of spallation particles were studied as parameters in the present paper. Under the given temperature and gas flow distributions in specified initial conditions, the trajectories of spallation particles flying in the polymer ablated arc were simulated numerically, considering the time variations in the temperature and the diameter of the particles. The results show that the highest flight altitude of the PA6 spallation particle flying in the PA6 ablated arc is affected by the initial particle diameter and velocity remarkably.

The rust layers generated on the surface of steel rebars embedded in reinforced concrete promote the crystallization of iron oxyhydroxides which exert sufficient crystallization pressure to damage the reinforced structure by cracking the cover concrete.

The purpose of this project was to investigate fast photoneutron production from a series of materials commonly used for backing neutron beam guides. Fast neutrons were knocked out of these materials by exposing them to to high-energy photons at the Tagged-Photon Facility at MAX-lab in Lund, Sweden. Liquid scintillator detectors at different angles around the targets registered the photoknockout neutrons. These fast-neutron detectors were energy calibrated using two well-understood gamma-ray sources. The energy calibrations were used to establish the hardware detector thresh- olds. The hardware thresholds server as input to an absolute neutron-detection efficiency Monte Carlo simulation known as STANTON, which was used to establish the best-case neutron-detection efficiency achieved in the measurement. Finally, the detector thresh- olds were increased in software to study the reduction in detection efficiency as a function of the increase in threshold. A complete overview of the project is presented., Neutrons are very small particles with no charge that you normally find in the nucleuses of atoms. Thanks to their lack of charge neutrons have very attractive properties when used to examine other materials. In this thesis a problem facing modern neutron sources, called spallation sources, is investigated.

Cold and thermal neutrons used in neutrons scattering experiments are produced in nuclear reactors and spallation sources. The neutrons are cooled to thermal or cold temperatures in thermal and cold moderators, respectively. The present study shows that it is possible to exploit the poor thermalizing property of 208Pb to design a broad spectrum moderator, i.e. a moderator which emits thermal and cold neutrons from the same position. Using 208Pb as a reflector filter material is shown to be slightly less efficient than a conventional beryllium reflector filter. However, when surrounding the reflector filter by a cold moderator it is possible to regain the neutrons with wavelengths below the Bragg edge, which are suppressed in the beryllium reflector filter. In both the beryllium and lead case surrounding the reflector filter with a cold moderator increases the cold brightness significantly compared to a conventional reflector filter. Keywords

Plate impact shock and spall recovery experiments were conducted to study the effects of peak shock stress on the substructure evolution and spall response of fully annealed 1100 aluminum. The substructure of the material evolves substantially with increase in peak shock stress ranging from 4 GPa to 9 GPa with dislocation debris uniformly distributed throughout the interior of the subgrain. Observations from substructure evolution in conjunction with spall failure results suggest that ductile fracture by void nucleation, growth, and coalescence was perhaps the dominant fracture mode for shock stresses up to approximately 8.3 GPa. Whereas, beyond 8.3 GPa the material softened possibly due to dislocation reorganization (dynamic recovery) and brittle intergranular fracture by decohesion with isolated pockets of nanovoids was perhaps the dominant fracture mode. The contributions of nanovoids to the dynamic recovery process, if any, were unresolved. Microhardness measurements show an increase in residual hardness throughout the shock stress range studied implying shock hardening up to approximately 8.3 GPa. This observation also suggests that thermal softening was not operative throughout the shock stress range studied. However, dynamic recovery was thermally influenced during shock loading., The original document contains color images. Published in Materials Science & Engineering A, v618 p596-604, 2014. Prepared in collaboration with the Johns Hopkins University, Baltimore, MD.

Multiple high velocity impacts are of particular concern to bullet resistant glass systems incorporating commercial tempered or heat strengthened glass as exterior or strike faces. Initial impact by a single projectile typically produces a quasi-symmetrical crater exhibiting the typical mirror, mist, and hackle regions with radial cracks propagating across the entire strike face. These radial cracks effectively reduce system survivability during subsequent impacts. Should an impact from a second projectile occur on the damaged glass, loosely constrained fragments would be forced in a direction away from the strike face resulting in less resistance to projectile penetration. Since a greater amount of material is ejected from the strike face, the second crater is often significantly larger than the first and exhibits extreme geometrical variation. The sequence of multiple impacts could be deduced from the size and geometry of the existing craters as these characteristics are relatively dependent on the radial crack pathways from the previous impacts. If the glass fragments were constrained in the strike face, it may be possible to increase the extent to which they interact with the projectile, each other, and the remaining material in lateral directions, further facilitating energy dissipation while reducing crater size. One proposed solution explored the simple application of a window film to the strike face with the purpose of increasing penetration resistance by way of limiting material loss. A three-dimensional laser scanner and analytical software were employed to capture a point cloud of each crater and facilitated dimensional analysis and comparison. Digital quantification of crater characteristics supported the findings that utilizing a film to confine fragments on the strike face effectively decreased the average crater size and improved the material performance during subsequent ballistic impacts in protective glass systems.

Scandium-47 (T1/=3.41d) forms stable complexes with aminopolycarboxylic acids, useful as tumor biomarkers or antigens. Its therapeutic beta emissions at 441.1 keV and 600.5 keV are coupled with an imageable 159.4 keV gamma to permit in vivo-tracking of compound biodistribution. Currently, its wider clinical application is hindered by lack of availability, even as interest grows in radioscandium-based pharmaceuticals. We have investigated the Ti-47(n,np)Sc-47, 50Ti(n,3p) Sc-47,V-nat(n,x)Sc-47, and Ti-nat(n,x)Sc-47 reactions as potential routes to therapeutically relevant quantities of Sc-47. Targets of V-nat, Ti-nat and enriched Ti-47 (95.7% isotopic abundnace) and Ti-50 (83.1%) oxide targets were exposed to the spallation neutrons resulting from the proton-irradiation of RbCl and Ga targets at the Los Alamos National Laboratory (LANL) Isotope Production Facility (IPF). Radioisotopic purities of 47Sc in excess of 90% are achieved by activation of Ti-47 targets with an instantaneous production rate of 0.29+/-0.03 micro-Ci/g per Ah, and small yields of Ca-47 produce Sc-47 with 100% purity from activation of Ti-50., The original document contains color images.

A general introduction to the status of the European Spallation Source ESS AB is given. As well as a general overview, the status of instruments and instrument design is presented. Particular attention is given to the instrument selection process, and how a proposal for a fundamental neutron physics beamline should be submitted. The contents of this presentation closely reflect the recently completed Technical Design Report for the ESS., Sponsors: Enigmass; European Spallation Source (ESS); Institut Laue-Langevin

A model for an accelerator-driven subcritical system to be operated as a source of cold neutrons for Condensed Matter research is developed at the conceptual level. Its baseline layout relies upon proven accelerator, spalattion target and fuel array technologies, and consists in a proton accelerator able to deliver some 67.5 mA of proton beam with kinetic energy 0.6 GeV, a pulse length of 2.86 ms, and repetition rate of 14 Hz. The particle beam hits a target of conventional design that is surrounded by a multiplicative core made of fissile/fertile material, composed by a subcritical array of fuel bars made of aluminium Cermet cooled by light water poisoned with boric acid. Relatively low enriched uranium is chosen as fissile material. An optimisation of several parameters is carried out, using as components of the objective function several characteristics pertaining the cold neutron pulse. The results show that the optimal device will deliver up to 80% of the cold neutron flux expected for some of the ongoing projects using a significantly lower proton beam power than that managed in such projects. The total power developed within the core rises up to 22.8 MW, and the criticality range shifts to a final keff value of around 0.9 after the 50 days cycle. © 2014 Elsevier B.V.

This thesis presents an alternate, spallation, nucleosynthesis mechanism in the context of the dual-shock Quark Nova (dsQN). The dsQN is an evolutionary channel where a core collapse supernova is followed by the detonation of its neutron star - an event that generates nuclear spallation reactions. Spallation produces new, daughter isotopes, by the fragmentation of larger nuclei - in contrast to conventional nucleosynthesis models which are based on the accretion of smaller nuclei and particles into larger nuclei. This spallation nucleosynthesis model is fairly extensive - it can produce abundant isotopes in the A < 130 mass range and therefore solve some of the issues faced by conventional r-process models. Furthermore, the specificities of dsQN spallation might be the key to explain the peculiarities of 44Ti production in the universe. Finally, dsQN spallation nucleosynthesis is fairly robust in relation to the universe’s age and the chemical composition of core-collapse supernovae.

Presented at ASETSDefense 2012: Sustainable Surface Engineering for Aerospace and Defense Workshop held in San Diego, CA on 27-30 Aug 2012. Sponsored in part by SERDP. Prepared in collaboration with ES3, Inc., Clearfield, UT.

Numerous experimental investigations clearly established that when soda lime glass is subjected to sufficiently high axial-stress/pressure, it displays a nonlinear mechanical response and deformation irreversibility (inelasticity). This portion of the material behavior is often neglected in material models for glass which tend to focus on the damage and fracture phenomena of the material. However, material nonlinearity/ inelasticity can, in principle, have a profound effect on wave/shock propagation phenomena and processes (e.g. spall fracture). Within the present work, the effect of material nonlinearity and inelastic behavior on the dynamic response (including spallation) of soda lime glass is studied under symmetric flyer-plate loading conditions using computational methods and tools. Material nonlinearity and deformation irreversibility are modeled in two different ways: (a) as a non-linear elastic material response with no deformation irreversibility; and (b) as a linear-elastic, volumetrically-plastic deformation response. Incorporation of nonlinearity and inelasticity phenomena into a continuum-level material model for soda lime glass recently developed by the authors revealed that while these phenomena do not measurably affect spall resistance (as measured by a minimum flyer-plate velocity resulting in spallation), they provide beneficial linear momentum/ kinetic energy reduction effects., Published in Materials and Design, v35 p144 155, 2012. Prepared in cooperation with the Dept of Mechanical Engineering, Clemson Univ, Clemson, SC. Additional ARO contract no. W911NF-09-1-0513.

Spallation is a fracture mode commonly observed in ballistically/blast-wave-loaded structures. The interaction between decompression waves generated within the target structure produces tensile stresses which, if of a sufficient magnitude, may cause material damage and ultimate fracture (spallation). In this study, the phenomenon of spall-fracture is analyzed within a one-dimensional Lagrangian framework. Two distinct analyses are carried out. Within the first analysis, decompression waves are treated as decompression shocks, which simplified the analysis and enabled the formation of spallation-strength-based material index. In the second analysis, decompression waves are treated as smooth (centered simple) waves. This increased the fidelity of the computational analysis, but the material-selection procedure could be done only numerically and an explicit formulation of the spallation-strength-based material-selection index could not be carried out. Overall, the two analyses yielded similar results for the spallation-strength-based material-selection criterion suggesting that the simpler (decompression shock based) one is still adequate for use in the material-selection process., Published in the Journal of Materials Engineering and Performance, v21 n9 p1813-1823, Sep 2012. Prepared in collaboration with the Pennsylvania State Univ, University Park, PA and the Department of Mechanical Engineering, Clemson Univ, Clemson, SC.

The Air Force is extremely concerned with the safety of its people, especially those who are flying aircraft. Aircrew members flying combat missions are concerned with the chance that a fragment from an exploding threat device may penetrate into the airframe to possibly ignite a fire onboard the aircraft. One concern for vulnerability revolves around a flash that may occur when a projectile strikes and penetrates an aircraft's fuselage. When certain fired rounds strike the airframe, they break into fragments called spall. Spall and other fragmentation from an impact often gain enough thermal energy to oxidize the materials involved. This oxidation causes a flash. To help negate these incidents, analysts must be able to predict the flash that can occur when a projectile strikes an aircraft. This research directly continues AFIT work for the 46th Test Group, Survivability Analysis Flight, by examining models to predict the likelihood of penetration of a fragment fired at a target. Empirical live-fire fragment test data are used to create an empirical model of a flash event. The resulting model provides an initial back-face flash modeling capability that can be implemented in joint survivability analysis models., The original document contains color images.

In 2003 the joint European effort to design a European Spallation Source (ESS) resulted in a set of reports, and in May 2009 Lund was agreed to be the ESS site. The ESS Scandinavia office has since then worked on setting all the necessary legal and organizational matters in place so that the Design Update and construction can be started in January 2011, in collaboration with European partners. The Design Update phase is expected to end in 2012, to be followed by a construction phase, with first neutrons expected in 2018-2019.

We propose a new method for determination of temperature in spallation events. It is shown that temperature can be determined by applying the friction model of energy dissipation in participant-spectator model of a spallation process. First order estimate of temperature dependence of the participant zone on reaction Q-value is obtained from the Fermi gas model considerations. The heat diffusion process is also discussed.

The research conducted was a feasibility study using Lithium Fluoride-Beryllium Fluoride (LiF-BeF2) or FLiBe as a coolant with a natural uranium neutron spallation source applied to an accelerator driven sub-critical molten salt reactor. The study utilized two different software tools, MCNPX 2.6 and FLUENT 12.1. MCNPX was used to determine the neutronics and heat deposited in the spallation target structure while FLUENT was used to determine the feasibility of cooling the target structure with FLiBe. Several target structures were analyzed using a variety of plates and large cylinders of natural uranium with a proton beam incident on a Hastelloy-N window. The supporting structures were created from Hastelloy-N due to their anti-corrosive properties of molten salts such as FLiBe and their resistance to neutron damage. The final design chosen was a "Sandwich" design utilizing a section of thick plates followed by several smaller plates then finally a section of thick plates to stop any protons from irradiating the bottom of the target support structure or the containment vessel of the reactor. Utilizing a proton beam with 0.81 MW of proton beam power at 1.35 mA with proton kinetic energies of 600 MeV, the total heat generated in the spallation target was about 0.9 MW due to fissions in the natural uranium. Additionally, the neutrons produced from the final design of the spallation target were approximately 1.25x1018 neutrons per second which were mainly fast neutrons. The use of a natural uranium target proved to be very promising. However, cooling the target using FLiBe would require further optimization or investigation into alternate coolants. Specifically, the final design developed using FLiBe as a coolant was not practically feasible due to the hydraulic forces resulting from the high flow rates necessary to keep the natural uranium target structures cooled. The primary reason for the lack of a feasible solution was the FLiBe as a coolant; FLiBe is unable to pul

This report reviews the dynamic failure of materials. Compared to static or quasi-static failure, dynamic failure deals with the fracture process for which the effects of inertia cannot be ignored. Dynamic failure, when compared to the well-established classical fracture mechanics, is considered to be a relatively new field of study. For clarity, this report is divided into several sections. The first section is a brief historical background on the dynamic failure process, followed by a concise description of ductile fracture of homogeneous materials from the spallation and fragmentation point of view. The brittle fracture process is then briefly described from the dynamic failure point of view. Lastly, both numerical and experimental techniques used for studying dynamic failure are described. This report is not an exhaustive review on the topic of dynamic fracture but provides enough relevant information for the basic understanding of the dynamic fracture process., The original document contains color images.

A new composite armor concept that encompasses an extremely hard first layer to deform the projectile, an orthotropic second layer to slow down the shock wave propagation, a third porous layer to absorb the shock wave energy through PV-work, and a fourth layer to provide confinement for the porous medium has been conceived. Ceramic Corbit-98 and Ceramet Tungsten Carbide were selected as candidate materials for the first layer and these were the focus of this research. Dynamic loading responses of the material studied were determined through planar impact experiment conducted on a single stage light-gas gun at NPS Impact Physic Lab. Impact velocities ranged from 0.2 to 0.35 km/s. The impactor material for asymmetric experiments was z-cut single crystal sapphire. Diagnostic used included a VISAR system, to measure particle velocities, PZT pins to measure onset of impact, and contact pins to measure impactor velocities and tilt angles. Through this study, dynamic loading response of ceramic Corbit-98 and ceramet tungsten carbide were determined. The Hugoniot EOS for Corbit-98 ceramic and GC-915 tungsten carbide were measured to be Us 0.959*Up y10.57 and Us 10.2*Up y5.42, respectively. The Hugoniot Elastic Limit (HEL) of GC-915 was found to be 0.935 GPa and spall strength of approximately 2 GPa was also measured.

As part of the U.S. Department of Defense Explosives Safety Board (DDESB) Project ESKIMORE, the Science Panel Impact Debris Evaluation and Review (SPIDER) test program has been planned to develop improved predictions for the hazards inside an exposed site (ES) from fragments and debris. Data collected includes the mass and velocity required for perforation of the test cross-section and characteristics of all debris produced inside the ES. The 2004 SPIDER 1 test program tested the hazard from high-angle debris striking typical roof sections at terminal velocity. Similarly, the 2009 SPIDER 2 test program conducted at Redstone Arsenal tested the effect of debris and fragments impacting wall cross-sections. The wall response (e.g. penetration, deformation, spalling, breaching, perforation) to variable masses and velocities of spherical steel and concrete impactors was determined. Impact velocity and residual velocity of perforating fragments and ES debris were measured for each test. A trajectory analysis was used to choose SPIDER 2 steel and concrete impactor characteristics consistent with the masses, initial potential explosion site (PES) debris velocities (< 3000 fps), and low launch angles (< 15 degrees) that can critically impact walls at 500 to 3000 ft from the PES. Primary steel fragments, with initial velocities of < 5000 fps, were also included in the trajectory analysis., See also ADM002313. Department of Defense Explosives Safety Board Seminar (34th) held in Portland, Oregon on 13-15 July 2010. Document contains briefing charts. The original document contains color images.

This thesis examines the influences of five factors on the strain energy at failure of metallic alloy plates during a shock wave impact. The five factors are material type, initial damage, boundary conditions, plate thickness, and plate temperature. The finite element simulation matrix was developed using a statistical design of experiments (DOE) technique. The Eulerian hydrocode CTH was used to develop the pressure histories that were input into the finite element code Abaqus/Explicit, which implemented the Mississippi State University internal state variable (ISV) plasticity-damage model (DMG). The DMG model is based on the Bammann-Chiesa-Johnson (BCJ) ISV plasticity formulation with the addition of porosity and the void nucleation, growth, and coalescence rate equations that admit heterogeneous microstructures. Material type and thickness were the primary influences on the strain energy at failure, and the materials studied, magnesium and aluminum, showed two different failure mechanisms, tearing at the boundaries and spalling, respectively., The original document contains color images.

This research investigates sessile drop interfacial reactions between two refractory materials (high-chromia and alumina) and two synthetic slags (coal and petcoke). Pulverized slag samples were placed at specific microstructure locations on refractory substrates and heated to 1500 deg C at log(Po2) = -9, using a high-speed heating chamber. Cross-sections of the slag/refractory interface indicated unique slag penetration into preferred areas of the refractory and grain dissolution into the slag through a de-bonding mechanism. Initially, the slag attacked both grain boundaries and fine microstructure areas, freeing alumina grains into the slag. Crystalline VOx formation in the petcoke slag was found to alter the overall liquid composition. Chemical spallation of Cr-containing crystal layer facilitated degradation of the refractory., See also ADM002300. Presented at the Minerals, Metals and Materials Annual Meeting and Exhibition (138th) (TMS 2009) held in San Francisco, CA on 15-19 Feb 2009. Sponsored in part by the Navy. U.S. Government or Federal Purpose Rights. Published in Supplemental Proceedings: Volume 2: Materials Characterization, Computation and Modeling, p197-204, 2009.

This is the second part of three-part series that investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-VAR M50, and VIM-VAR M50NiL steels. A systematic investigation of effects of rolling contact fatigue (RCF) on evolution of material properties and micro-structural changes resulting in spall propagation rate has not been conducted. As a first step toward understanding spall propagation, we present stress distribution in the neighborhood of a spall initiated by RCF by an indent on a hybrid 40mm ball bearing. Elastic and elastic-plastic subsurface stress fields are computed using finite element models that incorporate the full three-dimensional (3D) ball-raceway geometry. The stress fields predicted indicate extensive yielding around the spall edges. The spall is shown to widen first axially across the width of the raceway, causing the ball to unload as it enters the spall. Effect of potential impact on the spall trailing edge is also considered. The proposed scenario involves repeated application of contact stress resulting from a combination of ball static and impact loads., See also ADA510506, ADA510508.

This paper is the first part of a three-part series which investigates the rolling contact fatigue (RCF) initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-V AR AISI M50, and VIM-V AR M50NiL steels. Although there is substantial prior work published on the rolling contact fatigue initiation of these materials, little has been published on their spall propagation characteristics after spall initiation. It is recognized that rapid spall growth can lead to catastrophic bearing failure. Hence, understanding the spall growth phase and factors which may cause accelerated growth rates is key to achieving a reliable and robust bearing design. The end goal is to identify control parameters for optimizing bearing materials for improved spall growth resistance. This first part study features the experimental results from 208-size (40 mm bore) angular-contact ball bearings endurance life tested at maximum Hertzian contact stress levels of 3.10 GPa and bearing outer race temperatures up to 131?C. Spall propagation experiments were conducted on new and life tested bearings at 2.10 and 2.4 1 GPa maximum contact stress., See also ADA510507, ADA510508.

A hydrothermal flame is a flame that exists in a supercritical aqueous medium and is characterized by steep temperature and density gradients. The overall objective of our project was to increase understanding of heat, mass, and momentum transport processes within hydrothermal flames. Specifically, we planned to study hydrothermal flame characteristics such as flame temperature and stability, and to develop a method for modeling heat and mass transport processes in the hydrothermal flame and supercritical water environments based on experimental observations. With this knowledge, hydrothermal flames can be tailored to the task of destroying aqueous wastes such as chemical and biological warfare agents or municipal sludges, or used to perform thermal spallation and/or fusion of rock surfaces in a deep-borehole environment for rock drilling and excavation. An autoclave reaction system was designed and constructed to create flame jets in water using both methanol and hydrogen as fuel at a pressure of 250 bar. The temperatures of these flames were measured, and attempts were made to use the flames to spall small rock samples. The experimental system was modified to study the centerline temperature decay of supercritical water jets injected at temperatures up to 525 degrees C into ambient temperature water. A device for measuring the heat flux from these jets was designed, constructed, and used to determine the heat transfer coefficients of the jets impinging against a flat surface. Together, these studies indicate that the necessary temperatures and heat fluxes required to induce thermal spallation in rocks can be achieved in a deep borehole. A detailed account of the experiments and results summarized below is available in Thesis Dissertation "Hydrothermal Spallation Drilling and Advanced Energy Conversion for Engineered Geothermal Systems" by Chad Augustine.

This is the third part of a three-part series which investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-VAR M50, and VIM-VAR M50 NiL steels. While there is substantial prior work published on the rolling contact fatigue initiation of these materials, little is known about their spall propagation characteristics after spall initiation. In Part III, 208 size, 40 mm bore bearings are examined for changes in appearance of the microstructure; as well as residual stress as a function of depth in the circumferential direction. Correlations between experimental results from Part I and computer modeling in Part II are made., See also ADA510506, ADA510507.

The governing mechanisms of fatigue spall propagation in ball bearing inner raceways are investigated through the use of elastic-plastic finite element modeling, X-Ray Diffraction, and the visual inspection of fatigue spall cracks. The model simulates multiple ball impacts with a fatigue spall's edge in a 208 size ball bearing operating at 10,000 rpm. Ball impacts are shown to cause severe plastic deformation within the spall edge and induce tensile residual stresses. The finite element results are supported by X-Ray Diffraction measurements and the locations of cracks observed around the edge of a spall., In-house contract. Performed in collaboration with the Universtity of Florida, Gainesville, FL. Submitted for publication in the Society of Tribologists and Lubrication Engineers.

Delayed scale failure was examined for samples of a Ni(Pt)Al-coated CMSX4 single crystal superalloy, cyclically oxidized at 1150 degrees C for 2000 hr. One sample exhibited accentuated coating grain boundary wrinkling, initiating local alumina scale spallation to bare metal, resulting in a final weight loss of 3.3 milligrams/(square centimeter). Spallation under ambient conditions was monitored with time after cooldown and was found to continue for times up to 24 hr, producing up to 0.05 milligrams/(square centimeter) additional loss for each hold, and accumulating 0.7 milligrams/(square centimeter) (20% of the total) over the course of the test. After test termination, water immersion produced an additional 0.15 milligrams/(square centimeter) loss. (A duplicate sample produced much less wrinkling and time dependent spalling, maintaining a net weight gain). The results are consistent with the general phenomena of moisture-induced delayed spallation (MIDS) of mature, distressed alumina scales formed on oxidation resistant MAl alloys. Relative ambient humidity is discussed as the factor controlling adsorbed moisture, reaction with the substrate, and hydrogen effects on interface strength., Document contains briefing charts.

The objective of this delivery order was to fully support and accomplish research and development, planning, program management, test and analyses of advanced combustion concepts, mechanical systems, lubricants and fuels for aerospace propulsion and power programs for the Air Force Research Laboratory (AFRL)., Prepared in cooperation with Universal Technology Corporation.

Multilayered hybrid metal laminates have been studied for structural applications due to their potential for higher strength, toughness, and stiffness. The goal of this study was to modify the microstructure and mechanical properties of commercial purity titanium (CP-Ti) and 1100 aluminum (Al) laminates for potential applications in mine blast mitigation. Alternating layers of 50 micron thick CP-Ti and Al layers were ultrasonically consolidated. To provide high hardness and stiffness, the consolidated laminates were heat-treated in a variety of conditions to form intermetallic titanium aluminide (TiAl3) layers. The resulting CPTi/ TiAl3/Al laminates were characterized by scanning electron microscopy. Plate impact testing, an instrumented laboratory scale test to characterize the dynamic spall behavior of the material, was conducted on select laminates. Based on these results, the CP-Ti/TiAl3/Al laminate had a higher spall strength compared to the Cp-Ti/Al laminate., Presented at The Minerals, Metals & Materials Society Annual Meeting & Exhibition (137th), TMS 2008, in New Orleans LA on 9-13 Mar 2008. Printed in Supplemental Proceedings: Volume I: Materials Processing and Properties, TMS (The Minerals, Metals & Materials Society), 2008. The original document contains color images.

A series of experiments were performed using five excavation methods on nominal 2-foot wide, by 2-foot long by 4-inch deep spalls. The objective of this research was to develop one or more methods that will allow field personnel to excavate and prepare a 2-foot wide by 2-foot long by 4-inch deep spall for placement of a rapid-setting repair material in fifteen minutes or less. A secondary objective was to correlate various excavation methods with a relative life expectancy of the repair. Each of the methods tested had a significant improvement in production rate over the 30-pound jackhammer. The most efficient method was the cold planer, which, on average, was approximately 58 percent more efficient than the jackhammer.

This paper highlights the hot tensile and accelerated creep properties of a thermal barrier coated (TBC) AE 437A alloy used as a candidate blade material in aero engines. Acoustic emission technique has been utilised to characterise the ductile-brittle transition temperature of the bond coat. Results revealed that the DBTT (ductile to brittle transition temperature) of this bond coat is around 923 K, which is in close proximity to the value reported for NiCoCrAlY type of bond coat. Finite element technique used for analysing the equivalent stresses in the bond coat well within the elastic limit, revealed highest order of equivalent stress at 1073 K as the bond coat is ductile above 923 K. The lifetime of the TBC coated superai loy was superior to that of the bare substrate and that oxidation is likely the cause of the reduced life of the bare substrate as compared to the coated substrate while stress rupture or accelerated creep experiments are carried out in an oxidizing environment.. Delamination of the bond coat and that of the TBC at high stresses during accelerated creep was evident. During accelerated creep, the mode of fracture in the substrate at very high stresses was transgranular whereas that at low stresses was intergranular.

RESEARCH FOCUS AREAS: Low Observables; Signature Management; Mounted Weapons; Tactics; Obscurants; Jammers; EO Countermeasures; Active Protection; Sensors; Active/Passive Armor; Spall Liners; Fire Suppression; Laser Protection. * Detection * Acquisition * Hit * Penetrate * Kill., Presented at the Advanced Planning Briefing for Academia (APBA). Document consists entirely of briefing charts. The original document contains color images.