RADIATION DAMAGE

During the latest decade, experiments have been performed at the CERN SPS to investigate the use of high-energy channeled nuclei in bent crystals for extraction, beam splitting and beam bending. An understanding of channeling in a bent crystal with extraction and de¯ection eciencies for dierent energies, crystal types and ions has been developed. Furthermore, the long-standing question of radiation damage has been addressed with encouraging outcome. This makes extrapolations possible for the construction of, e.g., an extraction device for the LHC at CERN, RHIC at Brookhaven or new splitting elements in high-energy beams.We present the main results obtained and discuss existing and future applications of bent crystals in high-energy physics.

During the period November 15, 1991 through July 15, 1992, substantial progress :ras made on the research grant DE-FGO3-91ER54115. Three papers have been published in Journal of Nuclear Materials, and two other papers have been submitted for publication. In addition, two Ph.D. students formulated the topics of their theses, and made good progress towards the degree. The basic displacement damage process in SiC has been fully explored, and the mechanisms identified. Major modifications have been made to the theory of damage dosimetry in Fusion, Fission and Ion Simulation studies of SiC. For the first time, calculations of displacements per atoms in SiC can be made in any irradiation environment. Applications to irradiations in fusion first wall neutron spectra (ARIES and PROMETHEUS) ,as well as in fission spectra ( HIFIR and FFTF) are given. Nucleation of helium-filled cavities in SiC was studied, using concepts of stability t_eory to determine the size of the critical nucleus under continuous generation of helium and displacement damage, lt is predicted that a bimodal distribution of cavity sizes is likely to occur in heavily irradiated SiC. A study of the chemical compatibility of SiC composite structures with fusion reactor coolants at high-temperatures was undertaken, lt was shown that SiC itself is chemically very stable in helium coolants in the temperature range 500-1000 °C. However, current fiber/matrix interfaces, such as C and BN are not. The fracture mechanics of high-temperature matrix cracks with bridging fibers is now in progress. A fundamentally unique approach to study the propagation and interaction of cracks in a composite was initiated. The main focus of our research during the following period will be : (1) Theory and experiments for the micro-mechanics of high-temperature failure; and (2) Analysis of radiation damage and microstructure evolution.

Radiation damage parameters in SiC/SiC composite structures are determined in both magnetic (MFE) and inertial (IFE) confinement fusion systems. Variations in the geometry, neutron energy spectrum, and pulsed nature of neutron production result in significant differences in damage parameters between the two systems. With the same neutron wall loading, the displacement damage rate in the first wall in an IFE system is $10% lower than in an MFE system, while gas production and burnup rates are a factor of 2 lower. Self-cooled LiPb and Flibe blankets were analyzed. While using LiPb results in higher displacement damage, Flibe yields higher gas production and burnup rates. The effects of displacement damage and helium production on defect accumulation in SiC/SiC composites are also discussed.

This study, called APEX, is exploring novel concepts for fusion chamber technology that can substantially improve the attractiveness of fusion energy systems. The emphasis of the study is on fundamental understanding and advancing the underlying engineering sciences, integration of the physics and engineering requirements, and enhancing innovation for the chamber technology components surrounding the plasma. The chamber technology goals in APEX include: (1) high power density capability with neutron wall load \ 10 MW/m 2 and surface heat flux \ 2 MW/m 2 , (2) high power conversion efficiency ( \ 40%), (3) high availability, and (4) simple technological and material constraints. Two classes of innovative concepts have emerged that offer great promise and deserve further www.elsevier.com/locate/fusengdes

The design concept for the integration of the target and the focusing horn system for the proposed BNL neutrino oscillation experiment is described in this paper. Also presented are issues associated with the functionality and thermo-mechanical response of the selected target intercepting the 28 GeV protons of the 1 MW upgraded AGS beam, the loading and mechanical response of the focusing horn subjected to high currents and energy deposited due to beam/target interaction, the integration of the two systems, and the heat removal schemes. The proposed target intercepts the 8.9x10 13 , 28 GeV protons with a 2.5 Hz cycle time over a spot that encloses the 3σ of the beam. In the baseline design the inner conductor of the aluminum horn encloses the target while allowing for an annular space for forced cooling. Approximately 250 kA pulse of current of 20µs duration will flow through the horn at 2.5 Hz repetition rate inducing high compressive forces, vibration and heat. The paper addresses these issues of horn mechanical response, heat removal scenario, and useful life estimation including radiation damage.

X-ray free-electron lasers (XFELs) enable crystallographic structure determination beyond the limitations imposed upon synchrotron measurements by radiation damage. The need for very short XFEL pulses is relieved through gating of Bragg diffraction by loss of crystalline order as damage progresses, but not if ionization events are spatially non-uniform due to underlying elemental distributions, as in biological samples. Indeed, correlated movements of iron and sulfur ions were observed in XFEL-irradiated ferredoxin microcrystals using unusually long pulses of 80 fs. Here, we report a femtosecond time-resolved X-ray pump/X-ray probe experiment on protein nanocrystals. We observe changes in the protein backbone and aromatic residues as well as disulfide bridges. Simulations show that the latter’s correlated structural dynamics are much slower than expected for the predicted high atomic charge states due to significant impact of ion caging and plasma electron screening. This indicates ...

This study explores the optimization of Indium Gallium Phosphide (InGaP) solar cells through detailed simulations using PC1D software. The research focuses on the impact of active layer thickness and dopant concentration on the overall efficiency of solar cells. The maximum efficiency of 17.45% was achieved at a thickness of 175 μm and a dopant concentration of 1.1 × 1017 cm− 3for the base layer. Similarly, for the emitter layer, peak efficiency reached 17.45% at 1 μm thickness and the same dopant concentration. The study also evaluates the effects of various antireflection coatings (ARCs), including TiO2, ZnO, ZnS, SiO2, and SnO2, on the performance of the solar cell. By optimizing the reflectance, refractive index, thickness of the base, emitter, and antireflective coatings, the solar cell’s efficiency improved significantly. Among the tested ARCs, SnO2 demonstrated the best performance, leading to an increase in efficiency of up to 23.9%. The overall optimized solar cell design showed a current of 0.0374 A, a maximum power of 0.0149 W, and a maximum external quantum efficiency of 99% for optimized SnO2 ARC coating. This comprehensive analysis provides valuable insights into enhancing the design and fabrication of efficient InGaP solar cells, contributing to advancements in photovoltaic technology.

In this work, the implications of high field bias conditions in radiation-induced defect recovery in 3C-SiC crystals is studied. It is well known that transient heating effects (or thermal spikes) occur when energetic swift heavy ions (SHIs) deposit energy to the surrounding medium via ionization. Here, we explore the dynamics of this transient event under high background electric fields in 3C-SiC, which is what occurs when an ion strike coincides with field-sensitive volumes. In this study, we use the Ensemble Monte Carlo method to quantify how the energy deposition of the ionized regions change in response to high background electric fields. Subsequently, we study the relationship between the radiation-induced thermal spike and defect recovery using molecular dynamics simulations. We find that field strengths below the critical breakdown of wide bandgap devices are sufficient to exacerbate the localized heating, which subsequently enhances the defect recovery effect. This work is beneficial for 3C-SiC electronics and materials used in high radiation environments.

In this work, the implications of high field bias conditions in radiation-induced defect recovery in 3C-SiC crystals is studied. It is well known that transient heating effects (or thermal spikes) occur when energetic swift heavy ions (SHIs) deposit energy to the surrounding medium via ionization. Here, we explore the dynamics of this transient event under high background electric fields in 3C-SiC, which is what occurs when an ion strike coincides with field-sensitive volumes. In this study, we use the Ensemble Monte Carlo method to quantify how the energy deposition of the ionized regions change in response to high background electric fields. Subsequently, we study the relationship between the radiation-induced thermal spike and defect recovery using molecular dynamics simulations. We find that field strengths below the critical breakdown of wide bandgap devices are sufficient to exacerbate the localized heating, which subsequently enhances the defect recovery effect. This work is beneficial for 3C-SiC electronics and materials used in high radiation environments.

Though several studies have proved the radiation tolerance of silicon detectors at cryogenic temperatures, following room temperature irradiation, no previous investigation has studied the behaviour of detectors irradiated ''in situ'' at low temperatures. In this work, effects of irradiation of 450 GeV protons at 83 K will be presented, showing that after a dose of 1.2 Â 10 15 p cm À2 a charge collection efficiency (CCE) of 55% is reached at 200 V before the annealing. The same results were found at the end of the irradiation, after the sample has spent more then one year at room temperature. This shows that the CCE recovery by low temperature operation is not affected by the temperature of irradiation and by the reverse annealing.

The Intermediate Silicon Layers (ISL) detector is currently being built as part of the CDF II detector upgrade project. The ISL detector will signi"cantly improve tracking in the central region and, together with the Silicon Vertex detector, provide stand-alone 3D track information in the forward/backward regions. In this article, we present the quality of the production sensors manufactured by Hamamatsu Photonics, which account for roughly half of the silicon sensors used in the ISL detector.

A new radiation transport code has been coupled with an existing multimaterial fluidynamics code using Adaptive Mesh Refinement (AMR) and its testing is presented, solving ray effect and shadow problems in S N classical methods. Important advances in atomic physics, opacity calculations and NLTE calculations, participating in significant experiments (LULI/France), have been obtained. Our new 1D target simulation model allows considering the effect of inverse Compton scattering in DT x targets (x<3%) working in a catalytic regime, showing the effectiveness of such tritium-less targets. Neutron activation of all natural elements in IFE reactors for waste management and that of target debris in NIF-type facilities have been completed. Pulse activation in structural walls is presented with a new modeling. Tritium atmospheric dispersion results indicate large uncertainties in environmental responses and needs to treat the two chemical forms. We recognise recombination barriers (metastable defects) and compute first systematic high-energy displacement cascade analysis in SiC, and radiation damage pulses by atomistic models in metals. Using Molecular Dynamics we explain the experimental evidence of low-temperature amorphization by damage accumulation in SiC.

Headlamps serve the purpose of an eye to an automobile both in style and function. They illuminate the road space in front of the automobile and ensure the dual purpose of to see and to be seen. The aim of this project was to design an automotive headlamp considering style and performance. A study of various headlamps designs available is made to understand the basic requirements of a headlamp and to understand the latest technologies being used inside the headlamp. The standard norms that need to be followed in design and installation were reviewed. A user study was conducted and customer voice was converted into technical voice and QFD was prepared. Three concept designs of headlamps were made and the final concept is selected using weighted ranking method. A detail design is made for the final selected concept. The finalised design concept is further validated using photometric and thermal analysis. A mock-up model is also made for the validated concept using polymer sheets. A be...

The application of the Hf isotope composition of zircon as a geochemical tracer requires the preservation of Lu-Hf systematics within individual grains. We performed hydrothermal experiments on a self-irradiation-damaged zircon to test whether hydrothermal alteration would affect its Hf isotopic composition. Severely radiation-damaged zircon from Sri Lanka was reacted in either Teflon reactors or gold capsules at 200 °C (1080 h, autogeneous pressure), 400 °C (120 h, 1 kbar), and 600 °C (72 h, 1 kbar) in a 1 M HCl-0.2 M HF solution that was spiked with 300 ppm non-natural Hf (98.2% 180 Hf) and 970 ppm Yb. Laser ablation inductively coupled plasma mass spectrometry measurements of the Hf-and U-Pb isotope compositions of the altered domains revealed that the U-Pb system of such domains was severely disturbed, resulting in a discordia pointing toward the origin of the concordia diagram, but that the Hf isotope composition was unaffected. In addition, Yb enrichment was observed in the reacted zircon domains, predominantly near the zircon-solution interface. The Yb has apparently diffused into the altered domains. The new data are fully consistent with a diffusion-controlled aqueous alteration process occurring within radiation-damaged zircon.

PURPOSE-Diffuse intrahepatic tumors are difficult to control. Whole liver radiotherapy has been limited by toxicity, most notably radiation-induced liver disease (RILD). Amifostine is a prodrug free-radical scavenger that selectively protects normal tissues and, in a preclinical model of intrahepatic cancer, systemic amifostine reduced normal liver radiation damage without compromising tumor effect.(1) We hypothesized that amifostine would permit escalation of whole liver radiation dose to potentially control microscopic disease. We also aimed to characterize the pharmacokinetics of amifostine and its active metabolite WR-1065 to optimize timing of radiotherapy. METHODS AND MATERIALS-We conducted a radiation dose escalation trial for patients with diffuse, intrahepatic cancer treated with whole liver radiation and intravenous amifostine. Radiation dose was assigned using the Time-to-Event Continual Reassessment Method. A companion pharmacokinetic study was performed. RESULTS-23 patients were treated, with a maximum dose of 40 Gy. Using a logistical regression model, compared to our previously treated patients, amifostine increased liver tolerance by 3.3 ± 1.1 Gy (p=0.007) (approximately 10%) with similar response rates. Peak concentrations of WR-1065 were 25 μM with an elimination half life of 1.5 hours; these levels are consistent with radioprotective effects of amifostine in patients. CONCLUSION-These findings demonstrate for the first time that amifostine is a normal liver radioprotector. They further suggest that it may be useful to combine amifostine with fractionated or stereotactic body radiation therapy for patients with focal intrahepatic cancer.

The study of temperature-dependent physical changes in flash-cooled macromolecular crystals is pertinent to cryocrystallography and related issues such as crystal annealing, X-ray radiation damage and kinetic crystallography. In this context, the unit-cell volume of flash-cooled trigonal and orthorhombic trypsin crystals has been monitored upon warming from 100 to 200 K and subsequent re-cooling to 100 K. Crystals of both forms were obtained under the same crystallization conditions, yet they differ in solvent content and channel size. An abrupt non-reversible unit-cell volume decrease is observed at 185 K in orthorhombic and at 195 K in trigonal crystals as the temperature is increased; this result is consistent with ultra-viscous solvent leaving the crystals. Concomitant appearance of ice rings in the diffraction patterns suggests that the transported solvent forms crystalline ice. These results demonstrate that solvent in flash-cooled protein crystals is liquid-like near its crys...

The fusion crust of eight A n tarctic meteorite nds show natural thermoluminescence (TL) levels about 100 times higher than the levels in the fusion crust of freshly fallen meteorites, Dhajala, Jilin and Bansur. If it is assumed that this TL is due to cosmic ray received on the surface of Antarctica, the terrestrial residence times of the meteorites is calculated to lie between 10 4 -1 0 5 years. Strictly, these periods represent l o wer limits of terrestrial ages of these meteorites, and are generally consistent with terrestrial ages calculated from cosmogenic radionuclides.

The LHC upgrade will extensively increase the area of silicon detectors used in the ATLAS experiment and require substantial changes to the readout system of both the ATLAS and CMS experiments. The two experiments are expected to use optical systems for part of the data and control paths which must withstand levels of radiation equivalent to a dose of approximately 400 kGy(Si) at 30 cm from the collision region (including a safety factor of 1.5). As part of the search for acceptably radiation hard optical fibres, four Graded Index multimode (GRIN) optical fibres and one single-mode (SM) fibre were tested to 650 kGy(Si) equivalent dose. One of the GRIN fibres was also tested at 5 different dose rates, in order to understand the dose rate effects. These tests have validated the radiation tolerance of a single-mode fibre and two multimode fibres for use at the SLHC for warm operation. Some interesting features of the time dependence of the fibre radiation damage and future plans are discussed.

The interaction of ionizing radiation with biological matter initiates a cascade of physical, chemical, and biological events that ultimately manifest as genetic mutations, cellular dysfunction, and carcinogenesis. While the direct interaction of high-energy photons or particles with DNA has been extensively studied over many decades, the role of secondary low-energy electrons (LEEs) in radiation damage has emerged as a critical paradigm in radiation biology only since the seminal experiments of Boudaffa and colleagues in 2000. These secondary electrons, with energies typically below 20 eV, outnumber direct ionization events by approximately 104 to 105 per MeV of deposited energy, making them the predominant agents of radiation-induced DNA damage in living cells. This work establishes a comprehensive theoretical framework for studying electron attachment in DNA through molecular orbital theory and quantum chemical approaches. We develop rigorous mathematical expressions for electron attachment energies, derive bounds on anion stability, formulate generalized charge transfer theories, and establish non-adiabatic quantum dynamics models for dissociative electron attachment and strand break formation. Our theoretical framework integrates Hartree-Fock theory, Møller Plesset perturbation theory, coupled-cluster methods, density functional theory with long-range corrected functionals, and Marcus theory generalized to nucleic acid systems. Nonadiabatic quantum dynamics is employed to model dissociative electron attachment processes. All computational validations are performed at the CCSD(T)/CBS level of theory, representing the gold standard in quantum chemical accuracy. We derive exact expressions for vertical attachment energies (VAEs) and adiabatic electron affinities (AEAs) within the context of Koopmans’ theorem extensions and electron propagator theory. The stability hierarchy of DNA transient negative ions (TNIs) is established as thymine > cytosine > guanine > adenine, with calculated VAEs of −0.54 eV, −0.48 eV, −0.62 eV, and −0.38 eV respectively, consistent with experimental observations from electron transmission spectroscopy and laser photodetachment experiments. The generalized Marcus theory predicts exponential distance dependence for superexchange with a decay constant β approximately 0.6–1.0 per angstrom and linear dependence for hopping, with a crossover at approximately 3–4 nanometers that marks the transition between coherent tunneling and incoherent hopping regimes. Dissociative electron attach ment to the sugar-phosphate backbone occurs with thresholds of 0.5–1.5 eV, aligning with experimental strand break cross-sections measured by electron bombardment of plasmid DNA and synthetic oligonucleotides. This work provides a foundation for predictive modeling of radiation damage at the molecular level and may guide the development of radioprotective agents and radiosensitizers for cancer therapy. The theoretical framework bridges fundamental quantum chemistry with biological radiation effects, offering quantitative predictions for mutation hotspots, radiosensitivity patterns, and electron transfer repair mechanisms that could inform the design of more effective therapeutic strategies. The implications extend beyond radiation biology into DNA nanotechnology, where charge transfer properties enable molecular device design, and into astrobiology, where low-energy electron interactions with organic molecules may illuminate prebiotic chemistry and the search for life beyond Earth.

Radiation damage in terms of atomic displacements in a typical CZT detector used in medical imaging applications was studied using the Monte Carlo statistical method. All detector structural and geometric features as well as different energies of the photons usually used in the application were taken into account. Considering the MottMcKinleyFeshbach classical approach, effective cross sections of the displacements were calculated, including the number of displacements per atom for each atomic species present in the material and each photon energy considered. These results are analyzed and compared. Finally, the radiation damage on CZT detector is compared to that calculated in a similar detector manufactured with other semiconducting materials. El daño radiacional en términos de desplazamientos atómicos en un típico detector de CZT empleado en aplicaciones de imagenología médica fue estudiado utilizando el método estadístico de Monte Carlo. Se tuvieron en cuenta todas las características estructurales y geométricas del detector, así como las diferentes energías de los fotones usualmente empleados en la aplicación. Considerando la aproximación clásica de MottMcKinleyFeshbach se calcularon las secciones eficaces de desplazamiento, así como el número de desplazamientos por átomo para cada especie atómica presente en el material y para cada energía considerada de los fotones. Estos resultados se analizan y comparan entre sí y finalmente se establece la comparación entre el daño radiacional que tiene lugar en el detector de CZT con el que se manifiesta en un detector similar, pero fabricado con otros materiales semiconductores.

Depleted monolithic CMOS active pixel sensors (DMAPS) have been developed in order to demonstrate their suitability as pixel detectors in the outer layers of a toroidal LHC apparatus inner tracker (ATLAS ITk) pixel detector in the high-luminosity large hadron collider (HL-LHC). Two prototypes have been fabricated using 150 nm CMOS technology on high resistivity (≥ 2 kΩ•cm 2 ) wafers. The chip size is equivalent to that of the current ATLAS pixel detector readout chip. One of the prototypes is used for detailed characterization of the sensor and the analog readout of the DMAPS. The other is a fully monolithic DMAPS including fast readout digital logic that handles the required hit rate. In order to yield a strong homogeneous electric field within the sensor volume, thinning of the wafer was tested. The prototypes were irradiated with X-ray up to a total ionization dose (TID) of 50 Mrad and with neutrons up to non-ionizing energy loss (NIEL) of 10 15 n eq /cm 2 . The analog readout circuitry maintained its performance after TID irradiation, and the hit-efficiency at > 10 -7 noise occupancy was as high as 98.9 % after NIEL irradiation.

ABSTRACT: PHENIX is one of the major experiments at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory. It has been exploring the spin structure of the nucleon utilizing polarized proton-proton collisions and characteristics of the Quark Gluon Plasma (QGP) created in heavy ion collisions. The Silicon Vertex Tracker (VTX) will be implemented in 2010 to enhance physics capabilities. It will be installed very close to the collision point and will cover | � | &lt; 1.2 and | � | ~2 � by four layers of silicon sensors. Inner two layers are silicon pixel detectors and outer two layers are silicon strip layers. In this paper, the inner silicon pixel detector is reported. We used 200 �m thick silicon sensor and readout chip developed for ALICE experiment. As a part of PHENIX detector, it needs to be read out by four times faster from ALICE experiment and to be thin in material to minimize the radiation length. To meet the criteria, the PHENIX silicon pixel detec...

Construction of IFMIF is planned to start in 6-8 years, following the Engineering Validation and Engineering Design Activity phase (EVEDA). The detailed engineering design of all the systems required for IFMIF and the test of system prototypes will be performed during this phase. One of the main systems will be the liquid lithium target. Two high energy deuteron beams will impact on a 20x5 cm 2 area producing an intense neutron flux of about 10 18 n/m 2 /s. The Li target is therefore the intersection of two sophisticated systems: the high energy deuteron beams and the Lithium loop. Several key parameters from the Li target must be controlled during the operation of IFMIF. The control of these parameters is important, not only for the operational of IFMIF itself, but also from the safety and licensing point of view. The Li temperature distribution on the target surface, the presence of surface waves and their amplitude, the pressure or the good performance of the back plate (behind the Li target and exposed at the maximum radiation flux) must be measured by some diagnostic systems that will be exposed to high radiation fields and/or some Li-atoms bombardment. Any of the proposed diagnostic systems may suffer intense radiation damage in some critical points as lenses, mirrors, metallic probes, etc. There are several known radiation effects, as swelling, optical absorption increase and radioluminescence in optical fibers or windows, change of refraction index in optical lenses, electrical degradation, etc, that may seriously affect the properties of materials or components giving rise to a malfunctioning of the whole diagnostic system. The experience during the research on the radiation effects on materials with applications in ITER produced a lot of information that may now be used for the assessment of radiation effects on Li-target diagnostic systems. The aim of this paper is the revision of some of the proposed diagnostic system, the estimation of the radiation dose rate in the most critical points of them, and the discussion of their performance taking into account the potential radiation effects together the experience developed during the last few years for ITER.

for the collection of diffuse diffraction data in anticipation of coherent x-ray imaging experiments that will be conducted at the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator Center (SLAC). The detector is designed to collect x-rays scattered from femtosecond pulses produced by the LCLS x-ray laser at framing rates up to 120 Hz. Because x-rays will arrive on femtosecond time scales, the detector must be able to deal with instantaneous count-rates in excess of 10 17 photons per second per pixel. A low-noise integrating front-end allows the detector to simultaneously distinguish single photon events in low-flux regions of the diffraction pattern while recording up to several thousand x-rays per pixel in more intense regions. The detector features a per-pixel programmable twolevel gain control that can be used to create an arbitrary 2-D, two-level gain pattern across the detector; massively parallel 14bit in-pixel digitization; and frame rates in excess of 120 Hz. The first full-scale detector will be 758 x 758 pixels with a pixel size of 110 x 110 microns made by tiling CMOS ASICs that are bumpbonded to high-resistivity silicon diodes. X-ray testing data of the first 185 x 194 pixel bump-bonded ASICs is presented. The measurements presented include confirmation of single photon sensitivity, pixel response profiles indicating a nearly single-pixel point spread function, radiation damage measurements and noise performance.

Optical properties of large size lead fluoride (PbF ) crystals of three different manufacturers and their degradation caused by Co -radiation have been investigated. Transmission losses have been systematically studied at absorbed energy doses between 0.1 and 7 kGy. Several radiation induced absorption bands have been observed. Optical bleaching with light of wavelengths 9365 nm has been found very effective to restore the original characteristics even after repeated irradiations. This observation together with the high density and the ultraviolet extended transmission make PbF an excellent choice for high rate and high resolution e.m. calorimetry.

Pyrochlore-structure oxides, A 2 B 2 O 7 , may exhibit remarkable radiation tolerance due to the ease with which they can accommodate disorder by transitioning to a defected fluorite structure. The mechanism of defect formation was explored by evaluating the radiation damage behavior of high quality epitaxial La 2 Zr 2 O 7 thin films with the defected fluorite structure, irradiated with 1 MeV Zr + at doses up to 10 displacements per atom (dpa). The level of film damage was evaluated as a function of dose by Rutherford backscattering spectrometry in the channeling geometry (RBS/c) and scanning transmission electron microscopy (STEM). At lower doses, the surface of the La 2 Zr 2 O 7 film amorphized, and the amorphous fraction as a function of dose fit well to a stimulated amorphization model. As the dose

In 11 0 02 substrates the wafer is cut along the 11 0 02 plane, i.e. along one face of the cubic cell; in 11 1 12 it is cut along the 11 1 12 plane, i.e. along the diagonal of the cubic cell. This has an impact on the interface with the SiO , given the di!erent amount of dangling bonds available in the two cases and how they interact with impurities.

Purpose: To elucidate with a histopathological study the mechanism of region-dependent volume effects in the partly irradiated parotid gland of the rat. Methods and Materials: Wistar rats were locally X-irradiated with collimators with conformal radiation portals for 100% volume and 50% cranial/caudal partial volumes. Single doses up to 40 Gy were applied. Parotid saliva samples were collected, and the three lobes of the parotid gland were examined individually on the macro-and micromorphologic level up to 1 year after irradiation. Results: Dose-dependent loss of gland weight was observed 1 year after total or partial X-irradiation. Weight loss of the glands correlated very well with loss of secretory function. Irradiating the cranial 50% volume (implicating a shielded lateral lobe) resulted in substantially more damage in terms of weight loss and loss of secretory function than 50% caudal irradiation (shielding the ventral and dorsal lobe). Histologic examinations of the glands 1 year after irradiation revealed that the shielded lateral lobe was severely affected, in contrast to the shielded ventral and dorsal lobes. Time studies showed that irradiation of the cranial 50% volume caused late development of secondary damage in the shielded lateral lobe, becoming manifest between 240 and 360 days after irradiation. The possible clinical significance of this finding is discussed. Conclusion: It is concluded that the observed region-dependent volume effect for late function loss in the rat parotid gland after partial irradiation is mainly caused by secondary events in the shielded lateral lobe. The most probable first step (primary radiation event) in the development of this secondary damage is radiation exposure to the hilus region (located between the ventral and dorsal lobe). By injuring major excretory ducts and supply routes for blood and nerves in this area, the facility system necessary for proper functioning of the nonexposed lateral lobe is seriously affected. The unexpected volume effect in the rat might have consequences for treatment strategies in radiotherapy, implicating not only salivary glands but also other organs with a seemingly homogeneous distribution of radiosensitive elements, a situation wherein volume effects have not been anticipated up to now.

The response of n + p silicon strip sensors to electrons from a 90 Sr source was measured using a multi-channel read-out system with 25 ns sampling time. The measurements were performed over a period of several weeks, during which the operating conditions were varied. The sensors were fabricated by Hamamatsu Photonics K. K. on 200 µm thick float-zone and magnetic-Czochralski silicon. Their pitch was 80 µm, and both p-stop and p-spray isolation of the n + strips were studied. The electrons from the 90 Sr source were collimated to a spot with a full-width-at-half-maximum of 2 mm at the sensor surface, and the dose rate in the SiO 2 at the maximum was about 50 Gy/d. After only a few hours of making measurements, significant changes in charge collection and charge sharing were observed. Annealing studies, with temperatures up to 80 • C and annealing times of 18 hours, showed that the changes can only be partially annealed. The observations can be qualitatively explained by the increase of the positive oxide-charge density due to the ionization of the SiO 2 by the radiation from the β source. TCAD simulations of the electric field in the sensor for different oxide-charge densities and different boundary conditions at the sensor surface support this explanation. The relevance of the measurements for the design of p + n strip sensors is discussed.

The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10 35 cm -2 s -1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.

Radiation induced defects in silicon diodes were investigated after exposure to high doses of Co-60 gamma irradiation, using Deep Level Transient Fourier Spectroscopy and Thermally Stimulated Current methods. The main focus was on differences between standard and oxygen enriched material and the impact of the observed defect generation on the diode properties. Two close to mid gap trapping levels and a bi-stable donor level have been characterized as function of dose. These defects explain the main macroscopic deterioration effects both in standard and oxygen enriched float zone diodes. Radiation damage effects in silicon detectors under severe hadron-and !ñirradiation are surveyed, focusing on bulk effects. Both macroscopic detector properties (reverse current, depletion voltage and charge collection) as also the underlying microscopic defect generation are covered. Basic results are taken from the work done in the CERN-RD48 (ROSE) collaboration updated by results of recent work. Preliminary studies on the use of dimerized float zone and Czochralski silicon as detector material show possible benefits. An essential progress in the understanding of the radiation induced detector deterioration had recently been achieved in gamma irradiation, directly correlating defect analysis data with the macroscopic detector performance.

Nuclear interactions can be the source of atomic displacement and post-short-term cascade annealing defects in irradiated structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoils kinematics of neutral, residual, charged and multi-particle emissions are now more rigorously treated based on modern, complete and enhanced nuclear data parsed in state of the art processing tools. Defect production metrics are the starting point in this complex problem of correlating and simulating the behaviour of materials under irradiation, as direct measurements are extremely improbable. The multi-scale dimensions (nuclear-atomic-molecular-material) of the simulation process is tackled from the Fermi gradation to provide the atomic-and meso-scale dimensions with better metrics relying upon a deeper understanding and modelling capabilities of the nuclear level. Detailed, segregated primary knockon-atom metrics are now available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, incident energy ranges and particles, and irradiations conditions to be explored, with sufficient data to adequately cover both standard applications and novel ones, such as advanced-fission, accelerators, nuclear medicine, space and fusion. This paper reviews the theory, describes the latest methodologies and metrics, and provides recommendations for standard and novel approaches.

This reportwas prepared as an accnuntof worksponsoredby the UnitedStatesGovernment.Neitherthe United States nor the Department of Energy,nor any of their employees,nor any of theircontractors, subcontractors, or theiremployees, makesany warranty, expressor implied, or assumesanylegalliabilityor responsibility fortheaccuracy, completeness, or usefulnessof anyinformation, aplwmtus, product orprocess disclosedorrepresents thatitsuse wouldnotinfringeprivately-owned rights.

The DIRC, a new type of ring-imaging Cherenkov detector that images internally reflected Cherenkov light, is being constructed as the main hadronic particle identification component of the BABAR detector at SLAC. The device makes use of 5 meter long fused silica (colloquially called quartz) bars, which serve both as the Cherenkov radiators and as light pipes for transmitting the light to an array of photo-multiplier tubes. This paper describes a program of research and development aimed at determining whether bars that meet the stringent requirements of the DIRC can be obtained from commercial sources. The results of studies of bulk absorption of fused silica, surface finish, radiation damage and bulk inhomogeneities are discussed.

The high luminosity requirements and the option of a polarized positron beam present a great challenge for the positron source of a future linear collider. This paper provides a comprehensive overview of the latest proposed design for the baseline positron source of the International Linear Collider (ILC). We report on recent progress and results concerning the main components of the source: including the undulator, capture optics, and target.

A comparison of possible undulator designs for the International Linear Collider positron source has resulted in a superconducting bifilar wire design being selected. After a comprehensive paper study and fabrication of the two preeminent designs, the superconducting undulator was chosen instead of the permanent magnet alternative. This was because of its superior performance in terms of magnetic field strength and quality, operational flexibility, risk of radiation damage, ease in achieving the required vacuum, and cost. The superconducting undulator design will now be developed into a complete system design for the full 200 m long magnet that is required.

This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3 fb -1 of integrated luminosity corresponding to an integrated charge of 0.055 C/cm in the hottest spot of the detector.

Measurements are presented of the reduction of signal output due to radiation damage for plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb -1 . The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: a laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60 Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate.

We investigated the evolution of microstructure and mechanical properties of sputter deposited AIlNb multilayers with individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keY He + ions with a dose of 6x 1 016/cm 2 . Helium bubbles, 1-2 nm in diameter, were observed. When h is greater than 25 nm, hardnesses of irradiated muItilayers barely change, whereas radiation hardening is more significant at smaller Transmission electron microscopy and scanning transmission electron microscopy studies reveal the fonnation of a thin layer of Nb3Al intermetallic along the AIlNb interface as a consequence of radiation induced intennixing. The dependence of radiation hardening on h is interpreted using a composite model considering the fonnation of the hard Nb3AI intennetal1ic layer.

The combination of high strength and high radiation damage tolerance in nanolaminate composites can be achieved when the individual layers in these composites are only a few nanometers thick and contain special interfaces that act both as obstacles to slip, as well as sinks for radiation-induced defects. The morphological and phase stabilities and strength and ductility of these nano-composites under ion irradiation are explored as a function of layer thickness, temperature and interface structure. Magnetron sputtered metallic multilayers such as Cu-Nb and V -Ag with a range of individual layer thickness from approximately 2 nm to 50 nm and the corresponding 1000 nm thick single layer films were implanted with helium ions at room temperature. Cross-sectional Transmission Electron Microscopy (TEM) was used to measure the distribution of " helium bubbles and correlated with the helium concentration profile measured vis ion beam analysis techniques to obtain the helium concentration at which bubbles are detected in TEM. It was found that in multilayers the minimum helium concentration to form bubbles (approximately I nm in size) that are easily resolved in through-focus TEM imaging was several atomic %, orders of magnitude higher than that in single layer metal films. This observation is consistent with an increased solubility of helium at interfaces that is predicted by atomistic modeling of the atomic structures of fcc-bcc interfaces. At helium concentrations as high as 7 at.%, a uniform distribution of I nm diameter bubbles results in negligible irradiation hardening and loss of deformability in multi layers with layer thicknesses of a few nanometers. The control of atomic structures of interfaces to produce high helium solubility at interfaces is crucial in the design of nano-composite materials that are radiation damage tolerant. Reduced radiation damage also leads to a reduction in the irradiation hardening, particularly at layer thickness of approximately 5 run and below. The strategies for design of radiation-tolerant structural materials based on the knowledge gained from this work will be discussed. This research isfunded by US DOE, Office of Basic Energy Sciences.

Mechanical testing and microstructural analysis was performed on an Alloy 718 window that was in use at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF) for approximately 5 years. It was replaced as part of the IPF preventive maintenance program. The window was transported to the Wing 9 hot cells at the Chemical and Metallurgical Research (CMR) LANL facility, visually inspected and 3-mm diameter samples were trepanned from the window for mechanical testing and microstructural analysis. Shear punch testing and optical metallography was performed at the CMR hot cells. The 1-mm diameter shear punch disks were cut into smaller samples to further reduce radiation exposure dose rate using Focus Ion Beam (FIB) and microstructure changes were analyzed using a Transmission Electron Microscopy (TEM). Irradiation doses were determined to be ~0.2-0.7 dpa (edge) to 11.3 dpa (peak of beam intensity) using autoradiography and MCNPX calculations. The corresponding irradiation temperatures were calculated to be ~34 o C to 120 o C with short excursion to be ~47 o C to 220 o C using ANSYS. Mechanical properties and microstructure analysis results with respect to calculated dpa and temperatures show that significant work hardening occurs but useful ductility still remains. The hardening in the lowest dose region (~0.2-0.7 dpa) was the highest and attributed to the formation of γ'' precipitates and irradiation defect clusters/bubbles whereas the hardening in the highest dose region (~11.3 dpa) was lower and attributed mainly to irradiation defect clusters and some thermal annealing.

A Silicon Microstrip Spectrometer was recently installed and operated in an 800 GeV proton beamline at Fermilab as a A Silicon Microstrip Spectrometer was recently installed and operated in an 800 GeV proton beamline at Fermilab as a major new component of experiment E789. The detectors received an estimated radiation exposure of up to 7.8 x 10lz major new component of experiment E789. The detectors received an estimated radiation exposure of up to 7.8 x 10lz minimum ionizing particles per cm* over a period of two months. We report on the changes in detector performance dtat we minimum ionizing particles per cm* over a period of two months. We report on the changes in detector performance dtat we have observed following preliminaty data analysis. have observed following preliminaty data analysis.

The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10 35 cm -2 s -1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.

We review recent contributions of Vilnius University teams in collaboration with others participating in the CERN RD39 and RD50 collaborations. These address detector technologies suitable for the proposed Super-LHC facility, capable of withstanding radiation levels arising from a luminosity of 10 35 cm -2 •s -1 which will present severe challenges to current tracking detector technologies. Candidates among those technologies for use as particle tracking detectors are cryogenic operation and/or defect engineering of Si detectors and GaN -a new semiconductor material for use as a particle tracking detector. The use of advanced methods for material characterization and the investigation of semi-insulating GaN are described in this paper. Peculiarities related to trap recognition in the temperature dependence of photoconductivity kinetics and recombination parameters in highly irradiated Si are presented, together with an overview of the promise of GaN as a radiation hard material. Keywords: recombination and trapping of charge carriers, III-V semiconductors, GaN photoluminescence, interaction of particles and radiation with semiconductors, methods of materials testing and analysis

Measurements are presented of the reduction of signal output due to radiation damage for plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb -1 . The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: a laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60 Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate.

Inelastic nuclear collisions of hadrons incident on silicon sensors can generate secondary highly ionising particles (HIPs) and deposit as much energy within the sensor bulk as several hundred minimum ionising particles. The large signals generated by these 'HIP events' can momentarily saturate the APV25 front-end readout chip for the silicon strip tracker (SST) sub-detector of the compact muon solenoid (CMS) experiment, resulting in deadtime in the detector readout system. This paper presents studies of this phenomenon through simulation, laboratory measurements and dedicated beam tests. A proposed change to a front-end component to reduce the APV25 sensitivity to HIP events is also examined. The results are used to infer the expected effect on the performance of the CMS SST at the future large hadron collider. The induced inefficiencies are at the percent level and will have a negligible effect on the physics performance of the SST.