This document discusses backscattering spectrometry, which uses elastic scattering of ions to determine the elemental composition of materials. It describes how Rutherford scattering can be used for low energy particles, while higher energies require solving the Schrodinger equation. Examples are given of using kinematic factors to identify elements in a spectrum and calculating stopping power and cross sections. The document outlines approaches for thin film analysis using peak integration and mean energy calculations to determine areal densities and stoichiometry.
This document discusses techniques for measuring birefringence in optical fibers. Birefringence is the difference in refractive indices for different polarization states. The beat length is the distance over which a state of polarization repeats and can be used to characterize birefringence. Several methods are presented: Rayleigh scattering detects polarization-dependent scattering patterns; magneto-optic modulation applies a magnetic field to induce birefringence; prism coupling couples light out of the fiber at angles related to propagation constants; and wavelength scanning analyzes modulation patterns with wavelength to determine beat length and birefringence. Each technique is described along with relevant setup diagrams.
This document discusses electron diffraction, including its principles and applications. Electron diffraction works by firing electrons at a sample and observing the scattering pattern, which can reveal information about the sample's structure. The key points covered are:
1. Electrons behave as waves and can diffract when passed through materials. Their wavelength depends on their energy.
2. Electron diffraction is used to determine bond lengths and angles in molecules by observing how the intensity of scattered electrons varies with angle.
3. Low-energy electron diffraction (LEED) analyzes surface structures by firing low-energy electrons at a sample's surface and observing the diffraction pattern.
4. LEED patterns reveal the two-dimensional arrangement of surface atoms
This document discusses laser beam characteristics including:
1. Lasers produce monochromatic, coherent beams with high directionality and low divergence.
2. Coherence refers to the correlation between the phases of waves and is measured both temporally and spatially.
3. An example calculates the coherence length and time for a laser beam filtered to have a bandwidth of 10 nm and wavelength of 532 nm.
Microelectronics Technology discusses advanced models for dopant diffusion. Advanced models account for electric field effects, concentration-dependent diffusion, and dopant segregation. Some models are based on point defect driven diffusion at the atomic scale. Modifications to Fick's laws are also discussed, including electric field enhancement effects which become important at higher doping concentrations. Process simulations demonstrate how electric fields can dominate doping distribution near MOS device source/drain regions. Concentration dependent diffusivities and dopant segregation effects are also covered.
Ion implantation is a process used to introduce impurity atoms into a crystalline substrate to modify its electronic properties. Ions are accelerated to high energies and bombard the silicon surface, penetrating the lattice and becoming embedded. It allows for extremely accurate control of the dopant dose and distribution. However, it is a complex process that can damage the semiconductor and require annealing. The distribution of implanted ions is typically Gaussian but is affected by backscattering and channeling effects. During annealing, the profile will diffuse but the initial profile complexity must be properly modeled.
1.crystal structure using x – ray diffractionNarayan Behera
The document discusses crystal structure determination using X-ray diffraction. It describes how X-rays are used to probe interatomic distances in solids and explains key concepts like Bragg's law, reciprocal lattices, and Miller indices that are used to index diffraction patterns and determine unit cell parameters and crystal structures. Examples of common crystal structures like NaCl, CsCl are given along with methods to analyze diffraction data.
This document discusses backscattering spectrometry, which uses elastic scattering of ions to determine the elemental composition of materials. It describes how Rutherford scattering can be used for low energy particles, while higher energies require solving the Schrodinger equation. Examples are given of using kinematic factors to identify elements in a spectrum and calculating stopping power and cross sections. The document outlines approaches for thin film analysis using peak integration and mean energy calculations to determine areal densities and stoichiometry.
This document discusses techniques for measuring birefringence in optical fibers. Birefringence is the difference in refractive indices for different polarization states. The beat length is the distance over which a state of polarization repeats and can be used to characterize birefringence. Several methods are presented: Rayleigh scattering detects polarization-dependent scattering patterns; magneto-optic modulation applies a magnetic field to induce birefringence; prism coupling couples light out of the fiber at angles related to propagation constants; and wavelength scanning analyzes modulation patterns with wavelength to determine beat length and birefringence. Each technique is described along with relevant setup diagrams.
This document discusses electron diffraction, including its principles and applications. Electron diffraction works by firing electrons at a sample and observing the scattering pattern, which can reveal information about the sample's structure. The key points covered are:
1. Electrons behave as waves and can diffract when passed through materials. Their wavelength depends on their energy.
2. Electron diffraction is used to determine bond lengths and angles in molecules by observing how the intensity of scattered electrons varies with angle.
3. Low-energy electron diffraction (LEED) analyzes surface structures by firing low-energy electrons at a sample's surface and observing the diffraction pattern.
4. LEED patterns reveal the two-dimensional arrangement of surface atoms
This document discusses laser beam characteristics including:
1. Lasers produce monochromatic, coherent beams with high directionality and low divergence.
2. Coherence refers to the correlation between the phases of waves and is measured both temporally and spatially.
3. An example calculates the coherence length and time for a laser beam filtered to have a bandwidth of 10 nm and wavelength of 532 nm.
Microelectronics Technology discusses advanced models for dopant diffusion. Advanced models account for electric field effects, concentration-dependent diffusion, and dopant segregation. Some models are based on point defect driven diffusion at the atomic scale. Modifications to Fick's laws are also discussed, including electric field enhancement effects which become important at higher doping concentrations. Process simulations demonstrate how electric fields can dominate doping distribution near MOS device source/drain regions. Concentration dependent diffusivities and dopant segregation effects are also covered.
Ion implantation is a process used to introduce impurity atoms into a crystalline substrate to modify its electronic properties. Ions are accelerated to high energies and bombard the silicon surface, penetrating the lattice and becoming embedded. It allows for extremely accurate control of the dopant dose and distribution. However, it is a complex process that can damage the semiconductor and require annealing. The distribution of implanted ions is typically Gaussian but is affected by backscattering and channeling effects. During annealing, the profile will diffuse but the initial profile complexity must be properly modeled.
1.crystal structure using x – ray diffractionNarayan Behera
The document discusses crystal structure determination using X-ray diffraction. It describes how X-rays are used to probe interatomic distances in solids and explains key concepts like Bragg's law, reciprocal lattices, and Miller indices that are used to index diffraction patterns and determine unit cell parameters and crystal structures. Examples of common crystal structures like NaCl, CsCl are given along with methods to analyze diffraction data.
The document discusses laser applications in optical communication and optical fibers. It describes how light is guided through optical fibers via total internal reflection. Key fiber optic concepts are explained, including core, cladding, numerical aperture, single mode vs multimode fibers, and mode field diameter. Examples of calculations for number of fiber modes and single mode fiber radius are provided.
2018 ELECTRON DIFFRACTION AND APPLICATIONSHarsh Mohan
Low energy electron diffraction (LEED) is a surface-sensitive technique used to determine the structure of crystalline surfaces. LEED works by firing low energy electrons (20-200 eV) at a sample surface and analyzing the diffraction pattern of elastically backscattered electrons on a fluorescent screen. The pattern provides information on the 2D periodic arrangement of atoms in the surface layer. LEED has advantages over x-ray diffraction for studying surfaces and thin films due to its surface sensitivity and ability to operate under vacuum conditions.
The document reports on an ARPES microscopy study of free-standing bilayer graphene. Key findings include:
1) Bilayer graphene samples were prepared by mechanical exfoliation on 5μm wells and studied using ARPES microscopy between 110-300K.
2) Analysis of ARPES data using a tight-binding model found the Fermi velocity to be 1.003-1.042×106 m/s, interlayer asymmetry Δ/2 = 48-56 meV, and interlayer coupling γ1 = 0.6-0.611 eV.
3) Additional trilayer graphene was studied at room temperature using a 74eV photon energy, showing a doped sample with a 350
This document discusses dopant diffusion, which is the process of introducing controlled amounts of chemical impurities into a semiconductor lattice. Dopant diffusion is used to form source, drain, base, and emitter regions in semiconductor devices. The document covers various diffusion techniques and parameters, including diffusion sources, solid solubility limits, Fick's laws of diffusion, analytical solutions to the diffusion equations, design of diffused layers, and an example design calculation for a boron diffusion process.
Ion implantation of aluminum oxide (alumina) with calcium and yttrium ions results in the formation of aluminum nanoparticles. High temperature annealing or implantation causes implanted ions to precipitate out as nanocrystals by reducing the alumina matrix. Transmission electron microscopy images show particles with the lattice spacing of aluminum embedded in the alumina matrix. Energy loss spectroscopy also indicates the presence of metallic aluminum plasmon peaks, confirming the particles contain aluminum.
Graded index (GRIN) optical fibers have a refractive index that decreases continuously from the core center to the cladding. This results in curved ray paths inside the core rather than straight lines, reducing intermodal dispersion. The optimal refractive index profile for minimizing dispersion is parabolic. Attenuation in optical fibers is due to various factors including material absorption, scattering, and bending losses. Rayleigh scattering increases at shorter wavelengths, while absorption peaks exist for hydroxyl and metal impurities.
This document summarizes an ARPES and SPE-LEEM study on supported, suspended, and twisted bilayer MoS2. The study directly measures the MoS2 band structure using SPE-LEEM to study the band gap transition and role of interlayer coupling in monolayer, bilayer, and twisted bilayer MoS2. It also studies the substrate effect by examining suspended MoS2. Preliminary results on effective mass and spin-orbit splitting are also presented.
A Study on Uniform and Apodized Fiber Bragg GratingsIJSRD
This document summarizes a study on modeling uniform and apodized fiber Bragg gratings (FBGs) using MATLAB. The authors simulate different FBG designs and analyze their reflection spectra and side lobe strengths. Uniform FBGs are affected by changes in grating length, refractive index modulation, and pitch. Increasing length increases reflectivity but decreases bandwidth, while increasing index modulation increases reflectivity and bandwidth. Apodized FBGs using Gaussian, sinc, and raised cosine profiles reduce side lobes compared to uniform FBGs, at the cost of lower reflectivity. Apodized FBGs are preferred over uniform FBGs when wavelength selectivity is important.
This document contains solutions to problems involving electromagnetic fields and magnetostatics. It includes calculations of permeability, magnetic field intensity, magnetization, inductance, magnetic torque, and energy stored in an inductor. Key concepts covered are relative permeability, magnetic flux, reluctance, ampere turns, self and mutual inductance. Calculations are shown for solenoids, toroids, and magnetic materials.
Electron Diffraction Using Transmission Electron MicroscopyLe Scienze Web News
Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The advantages of elec- tron diffraction over other methods, e.g., x-ray or neutron, arise from the extremely short wavelength (≈2 pm), the strong atomic scattering, and the ability to exam- ine tiny volumes of matter (≈10 nm3). The NIST Materials Science and Engineer- ing Laboratory has a history of discovery and characterization of new structures through electron diffraction, alone or in combination with other diffraction methods. This paper provides a survey of some of this work enabled through electron mi- croscopy.
X-ray diffraction is used to study crystal structures. X-rays are generated when high-speed electrons collide with atoms in a target material. X-rays are diffracted by crystal structures according to Bragg's law, where the path difference between diffracted rays is equal to an integer multiple of the wavelength. By analyzing diffraction patterns, properties of crystals like lattice parameters, crystallite size, and density can be determined.
2nd semester 3rd class a optics lab exam 2013Qahtan Al-zaidi
1. The document is an optics laboratory note for a physics class at Baghdad University that provides 12 questions on topics in optics.
2. The questions cover concepts like Heisenberg's uncertainty principle, diffraction grating calculations, Michelson interferometer principles, Malus' law, Newton's rings experiment analysis, and definitions of optical phenomena like optical activity.
3. Students are instructed to answer 7 of the 12 questions in detail for the lab assignment.
This document discusses various applications of lasers for optical alignment and tooling. It explains that lasers provide higher brightness than conventional light sources, making them visible from long distances. Both helium-neon and semiconductor diode lasers have been used for tooling applications such as determining displacement and establishing angles. Laser tooling requires only one operator and provides more consistent measurements between operators compared to conventional optical tooling.
This document provides an overview of nonlinear optics and second harmonic generation. It begins with an introduction to lasers and their components. It then discusses symmetry operations in crystals and how centrosymmetric and noncentrosymmetric materials affect nonlinear polarization. Maxwell's equations are presented for linear media. The document introduces nonlinear optics and lists various nonlinear optical effects such as second harmonic generation. It derives the wave equation for nonlinear media and shows how second harmonic generation leads to frequency doubling. Examples of nonlinear crystals used for second harmonic generation are also provided.
This document discusses fiber Bragg gratings (FBG), which are periodic variations in the refractive index of an optical fiber that reflect specific wavelengths of light. It provides an introduction to FBG, the basic theory behind how they work, common fabrication methods, applications as optical filters and sensors, and their advantages and disadvantages. Key points covered include how the Bragg wavelength is determined by the refractive index and grating period, common types of grating structures, and how FBG can be used as sensors for strain, temperature, and acceleration.
Younes Sina, Ion implantation and thermal annealing of α-Al2O3 single crystalsYounes Sina
This document describes an experiment involving ion implantation and thermal annealing of chromium ions in alpha aluminum oxide single crystals. Chromium ions were implanted at energies of 280-300 keV and doses of 1016-1017 ions/cm2. Backscattering spectroscopy measurements showed the implantation caused damage in the aluminum and oxygen sublattices but did not amorphize the surface region. Thermal annealing from 800-1600°C led to damage recovery and incorporation of chromium into substitutional lattice sites. Angular scans and calculations determined the chromium was substituting into sites in the aluminum sublattice rather than the oxygen sublattice.
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
Laser diode have to have a specific architecture in order to optimize the laser light leaving the waveguide. There are various factors that are to be precisely noted and put into certain equations in order to calculate the differential quantum efficiency and to improvise the design of the diode lasers. The slides explain about reservoir analogy, threshold and gain and photon density as well as carrier density rate equations. Glad if it helps :)
This document discusses different types of all-optical switches that use Bragg gratings and the Kerr effect. It describes a nonlinear directional coupler loaded with a Bragg reflector that can act as an all-optical switch, directing light to different ports based on the presence of a control light. It also discusses an optical fiber grating coupler all-optical switch and a periodically curved nonlinear waveguide all-optical switch, noting advantages like lower power requirements and sharper switching widths.
Optical sources convert electrical signals to optical signals for data transmission through fiber optic cables. They include LEDs, ELEDs, SLEDs, and laser diodes (LDs). LEDs produce incoherent light while laser diodes produce coherent light. Incoherent light sources are used for multimode fiber systems while laser diodes are used for single mode systems. Laser diodes must operate above the lasing threshold to produce coherent light, otherwise they function as ELEDs. Tunable lasers can produce coherent light of a controlled variable wavelength, allowing them to replace multiple light sources in multi-wavelength transmission systems.
Rutherford Backscattering Spectrometry: A Laboratory Didactic Path About the ...SEENET-MTP
The SEENET-MTP Seminar: Trends in Modern Physics
19–21 August 2011, Niš, Serbia
Talk by Frederico Corni, Faculty of Education, University of Modena аnd Reggio Emilia, Italy
The document discusses laser applications in optical communication and optical fibers. It describes how light is guided through optical fibers via total internal reflection. Key fiber optic concepts are explained, including core, cladding, numerical aperture, single mode vs multimode fibers, and mode field diameter. Examples of calculations for number of fiber modes and single mode fiber radius are provided.
2018 ELECTRON DIFFRACTION AND APPLICATIONSHarsh Mohan
Low energy electron diffraction (LEED) is a surface-sensitive technique used to determine the structure of crystalline surfaces. LEED works by firing low energy electrons (20-200 eV) at a sample surface and analyzing the diffraction pattern of elastically backscattered electrons on a fluorescent screen. The pattern provides information on the 2D periodic arrangement of atoms in the surface layer. LEED has advantages over x-ray diffraction for studying surfaces and thin films due to its surface sensitivity and ability to operate under vacuum conditions.
The document reports on an ARPES microscopy study of free-standing bilayer graphene. Key findings include:
1) Bilayer graphene samples were prepared by mechanical exfoliation on 5μm wells and studied using ARPES microscopy between 110-300K.
2) Analysis of ARPES data using a tight-binding model found the Fermi velocity to be 1.003-1.042×106 m/s, interlayer asymmetry Δ/2 = 48-56 meV, and interlayer coupling γ1 = 0.6-0.611 eV.
3) Additional trilayer graphene was studied at room temperature using a 74eV photon energy, showing a doped sample with a 350
This document discusses dopant diffusion, which is the process of introducing controlled amounts of chemical impurities into a semiconductor lattice. Dopant diffusion is used to form source, drain, base, and emitter regions in semiconductor devices. The document covers various diffusion techniques and parameters, including diffusion sources, solid solubility limits, Fick's laws of diffusion, analytical solutions to the diffusion equations, design of diffused layers, and an example design calculation for a boron diffusion process.
Ion implantation of aluminum oxide (alumina) with calcium and yttrium ions results in the formation of aluminum nanoparticles. High temperature annealing or implantation causes implanted ions to precipitate out as nanocrystals by reducing the alumina matrix. Transmission electron microscopy images show particles with the lattice spacing of aluminum embedded in the alumina matrix. Energy loss spectroscopy also indicates the presence of metallic aluminum plasmon peaks, confirming the particles contain aluminum.
Graded index (GRIN) optical fibers have a refractive index that decreases continuously from the core center to the cladding. This results in curved ray paths inside the core rather than straight lines, reducing intermodal dispersion. The optimal refractive index profile for minimizing dispersion is parabolic. Attenuation in optical fibers is due to various factors including material absorption, scattering, and bending losses. Rayleigh scattering increases at shorter wavelengths, while absorption peaks exist for hydroxyl and metal impurities.
This document summarizes an ARPES and SPE-LEEM study on supported, suspended, and twisted bilayer MoS2. The study directly measures the MoS2 band structure using SPE-LEEM to study the band gap transition and role of interlayer coupling in monolayer, bilayer, and twisted bilayer MoS2. It also studies the substrate effect by examining suspended MoS2. Preliminary results on effective mass and spin-orbit splitting are also presented.
A Study on Uniform and Apodized Fiber Bragg GratingsIJSRD
This document summarizes a study on modeling uniform and apodized fiber Bragg gratings (FBGs) using MATLAB. The authors simulate different FBG designs and analyze their reflection spectra and side lobe strengths. Uniform FBGs are affected by changes in grating length, refractive index modulation, and pitch. Increasing length increases reflectivity but decreases bandwidth, while increasing index modulation increases reflectivity and bandwidth. Apodized FBGs using Gaussian, sinc, and raised cosine profiles reduce side lobes compared to uniform FBGs, at the cost of lower reflectivity. Apodized FBGs are preferred over uniform FBGs when wavelength selectivity is important.
This document contains solutions to problems involving electromagnetic fields and magnetostatics. It includes calculations of permeability, magnetic field intensity, magnetization, inductance, magnetic torque, and energy stored in an inductor. Key concepts covered are relative permeability, magnetic flux, reluctance, ampere turns, self and mutual inductance. Calculations are shown for solenoids, toroids, and magnetic materials.
Electron Diffraction Using Transmission Electron MicroscopyLe Scienze Web News
Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The advantages of elec- tron diffraction over other methods, e.g., x-ray or neutron, arise from the extremely short wavelength (≈2 pm), the strong atomic scattering, and the ability to exam- ine tiny volumes of matter (≈10 nm3). The NIST Materials Science and Engineer- ing Laboratory has a history of discovery and characterization of new structures through electron diffraction, alone or in combination with other diffraction methods. This paper provides a survey of some of this work enabled through electron mi- croscopy.
X-ray diffraction is used to study crystal structures. X-rays are generated when high-speed electrons collide with atoms in a target material. X-rays are diffracted by crystal structures according to Bragg's law, where the path difference between diffracted rays is equal to an integer multiple of the wavelength. By analyzing diffraction patterns, properties of crystals like lattice parameters, crystallite size, and density can be determined.
2nd semester 3rd class a optics lab exam 2013Qahtan Al-zaidi
1. The document is an optics laboratory note for a physics class at Baghdad University that provides 12 questions on topics in optics.
2. The questions cover concepts like Heisenberg's uncertainty principle, diffraction grating calculations, Michelson interferometer principles, Malus' law, Newton's rings experiment analysis, and definitions of optical phenomena like optical activity.
3. Students are instructed to answer 7 of the 12 questions in detail for the lab assignment.
This document discusses various applications of lasers for optical alignment and tooling. It explains that lasers provide higher brightness than conventional light sources, making them visible from long distances. Both helium-neon and semiconductor diode lasers have been used for tooling applications such as determining displacement and establishing angles. Laser tooling requires only one operator and provides more consistent measurements between operators compared to conventional optical tooling.
This document provides an overview of nonlinear optics and second harmonic generation. It begins with an introduction to lasers and their components. It then discusses symmetry operations in crystals and how centrosymmetric and noncentrosymmetric materials affect nonlinear polarization. Maxwell's equations are presented for linear media. The document introduces nonlinear optics and lists various nonlinear optical effects such as second harmonic generation. It derives the wave equation for nonlinear media and shows how second harmonic generation leads to frequency doubling. Examples of nonlinear crystals used for second harmonic generation are also provided.
This document discusses fiber Bragg gratings (FBG), which are periodic variations in the refractive index of an optical fiber that reflect specific wavelengths of light. It provides an introduction to FBG, the basic theory behind how they work, common fabrication methods, applications as optical filters and sensors, and their advantages and disadvantages. Key points covered include how the Bragg wavelength is determined by the refractive index and grating period, common types of grating structures, and how FBG can be used as sensors for strain, temperature, and acceleration.
Younes Sina, Ion implantation and thermal annealing of α-Al2O3 single crystalsYounes Sina
This document describes an experiment involving ion implantation and thermal annealing of chromium ions in alpha aluminum oxide single crystals. Chromium ions were implanted at energies of 280-300 keV and doses of 1016-1017 ions/cm2. Backscattering spectroscopy measurements showed the implantation caused damage in the aluminum and oxygen sublattices but did not amorphize the surface region. Thermal annealing from 800-1600°C led to damage recovery and incorporation of chromium into substitutional lattice sites. Angular scans and calculations determined the chromium was substituting into sites in the aluminum sublattice rather than the oxygen sublattice.
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
Laser diode have to have a specific architecture in order to optimize the laser light leaving the waveguide. There are various factors that are to be precisely noted and put into certain equations in order to calculate the differential quantum efficiency and to improvise the design of the diode lasers. The slides explain about reservoir analogy, threshold and gain and photon density as well as carrier density rate equations. Glad if it helps :)
This document discusses different types of all-optical switches that use Bragg gratings and the Kerr effect. It describes a nonlinear directional coupler loaded with a Bragg reflector that can act as an all-optical switch, directing light to different ports based on the presence of a control light. It also discusses an optical fiber grating coupler all-optical switch and a periodically curved nonlinear waveguide all-optical switch, noting advantages like lower power requirements and sharper switching widths.
Optical sources convert electrical signals to optical signals for data transmission through fiber optic cables. They include LEDs, ELEDs, SLEDs, and laser diodes (LDs). LEDs produce incoherent light while laser diodes produce coherent light. Incoherent light sources are used for multimode fiber systems while laser diodes are used for single mode systems. Laser diodes must operate above the lasing threshold to produce coherent light, otherwise they function as ELEDs. Tunable lasers can produce coherent light of a controlled variable wavelength, allowing them to replace multiple light sources in multi-wavelength transmission systems.
Rutherford Backscattering Spectrometry: A Laboratory Didactic Path About the ...SEENET-MTP
The SEENET-MTP Seminar: Trends in Modern Physics
19–21 August 2011, Niš, Serbia
Talk by Frederico Corni, Faculty of Education, University of Modena аnd Reggio Emilia, Italy
This document provides guidance and prompts for developing an inquiry proposal. It discusses choosing an area of interest and developing inquiry questions. It emphasizes planning, including finding literature to inform the proposal, drafting ethics and title forms for feedback, and scheduling activities. The document prompts considering progress made, focusing the inquiry questions, and informal discussions with colleagues. It outlines the required components of the proposal and portfolio submission. Finally, it addresses ethical considerations like codes of practice, gaining permissions, and protecting participants.
El documento trata sobre la auditoría administrativa interna y externa. La auditoría interna y externa comparten el objetivo fundamental de revisar y evaluar todas las funciones de una empresa para mejorar la eficiencia y reducir costos. La auditoría administrativa debe quedar ubicada en un nivel jerárquico que le permita revisar cualquier unidad administrativa y tener autoridad sobre otros departamentos. La auditoría administrativa ofrece beneficios como determinar la efectividad de los sistemas y hacer recomendaciones para mejorarlos.
El documento proporciona los detalles de las comidas y meriendas consumidas por una persona durante un período de 24 horas, incluyendo los alimentos ingeridos, las cantidades, los lugares y los procesos culinarios. La persona comenzó el día con leche, tostadas y café para el desayuno, luego comió patatas asadas, carne a la barbacoa y ensalada para la comida. Para la merienda tomó patatas fritas y cacahuetes fritos y para la cena un sándwich de pan integral con salchichas f
The respiratory system consists of an upper respiratory tract and lower respiratory tract. The upper tract includes the nose, nasal cavity, pharynx and larynx. The lower tract includes the trachea, bronchi and lungs. The conducting portion transports air through the nose, pharynx and into the lungs. The respiratory portion, including alveoli in the lungs, performs gas exchange between the air and blood. Breathing involves inhalation that draws air into the lungs and exhalation that forces air out. The document describes the anatomy and functions of the different parts of the respiratory system.
O documento discute as principais novidades da versão HTML5, incluindo: 1) Suporte nativo para áudio, vídeo e gráficos através das tags <canvas>, <audio> e <video>; 2) Novos elementos semânticos como <header>, <footer> e <nav>; 3) Armazenamento local de dados com sessionStorage e localStorage.
A REVIEW PAPER ON STRENGTH AND DURABILITY STUDIES ON CONCRETE FINE AGGREGATE ...IAEME Publication
This document provides a review of literature on the use of recycled crushed glass as a replacement for fine aggregates in concrete. Several studies that investigated the strength and durability properties of concrete with fine aggregates replaced by 10-50% glass are summarized. Generally, the literature showed that concrete strength increased with glass replacement up to 20-30% compared to conventional concrete. Higher glass replacement or larger glass particles can increase the risk of alkali-silica reaction, but this can be reduced by using glass powder or supplementary cementitious materials. The review concludes that crushed glass can effectively replace a portion of fine aggregates in concrete, with improvements to strength and reductions in construction waste.
- A component diagram shows the organization and dependencies among physical software components, including source code, runtime code, and executables. It addresses the static implementation view of a system and represents high-level reusable parts.
- The key elements are components, interfaces, ports, and connectors. Components provide and require interfaces. Interfaces can be attached to ports, which control component interactions. Connectors link components through ports or interfaces.
- A deployment diagram models the physical deployment of artifacts across nodes like hardware. It shows the configuration of runtime processing nodes and the artifacts deployed on them, such as executable files, libraries, and tables.
O documento discute as novas características do HTML5, a nova versão do HTML. Apresenta os editores de código mais usados e conceitos básicos como tags, elementos, atributos e valores. Detalha estruturas como textos, links, imagens, vídeos, listas e tabelas. Por fim, aborda elementos de formulários.
The ear can be divided into three parts: external, middle, and internal. The external ear includes the auricle and external acoustic meatus. The middle ear contains the tympanic cavity and auditory ossicles that transmit vibrations. The internal ear includes the membranous labyrinth containing endolymph and the bony labyrinth enclosing it within the petrous bone. Sound waves enter the external ear and vibrations are transmitted through the ossicles to the fluid-filled cochlea of the internal ear.
This document provides guidance for students on conducting a professional inquiry project. It discusses various aspects of the inquiry process, including thinking creatively, communicating findings, and drafting the written analysis. Students are encouraged to think about how to explain their topic and embed ideas from literature. Examples are provided on analyzing literature quotes and effectively writing the analysis section. The document concludes by looking ahead to sending a sample of the analysis for feedback and discussing how to organize findings by identifying themes in the data.
Atomic data and spectral models for lowly ionized iron-peak speciesAstroAtom
This document discusses the need for reliable atomic data and spectral models for lowly ionized iron-peak species like Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. Current models are inaccurate, with predicted line intensities disagreeing with observations by factors of several. The goals of the project are to compute new atomic data, construct improved spectral and opacity models, and implement the models in photoionization codes. The document outlines challenges in modeling these ions and describes ongoing work using relativistic R-matrix methods to calculate improved collision strengths and photoionization cross sections.
SCF methods, basis sets, and integrals part IIIAkefAfaneh2
Some DFT implementations (such as Octopus) attempt to describe the molecular
Kohn–Sham orbitals on a real-space grid.
• A 3D simulation box is chosen together with a grid spacing, for example 0.5 a0. Then,
a grid in 3D is constructed and the SCF equations are solved on the grid.
• This is different from an MO-LCAO expansion in numerical AOs!
• Pseudopotentials are inevitable for real-space grid methods, but they are not required
when numerical AOs are used.
• A great advantage of the use of numerical AOs as in DMol3 is that the method is free
of the basis-set superposition error (BSSE).
• Because exact atomic orbitals are used, the atoms in a molecule cannot improve
their orbitals artificially using basis functions from other atoms.
Crystal structure determination uses X-ray diffraction to analyze the arrangement of atoms in crystals. X-rays are diffracted by the periodic lattice of a crystal in predictable ways. Bragg's law describes the conditions under which constructive interference occurs between X-rays reflected from different crystal lattice planes, producing intense diffracted beams. By measuring the angles and intensities of these diffracted beams, researchers can determine the size and shape of the unit cell and deduce the positions of atoms within the cell. The reciprocal lattice formalism relates diffraction phenomena to the periodicity of the crystal lattice.
This document discusses the electromagnetic modeling of large planar arrays using the Scale Changing Technique (SCT). SCT decomposes planar structures into hierarchical scales to reduce computational requirements. It expresses fields on orthogonal modes and computes scale-changing networks between domains to model coupling. The document presents applications of SCT to modeling infinite and finite reflectarrays, characterizing coupling in non-uniform arrays, and simulating 2D arrays under plane wave and horn excitation. SCT was shown to efficiently model multiscale arrays and characterize coupling while avoiding issues of conventional full-wave solvers.
Transmission Electron Microscope_Lecture1.pptxBagraBay
The transmission electron microscope can be used to image microstructural features at high magnifications, perform elemental analysis, and determine crystal structures. Samples must be thinly sectioned or ion milled to be electron transparent. Imaging techniques like bright field and dark field are used to reveal structural features based on diffraction contrast. Selected area diffraction patterns can be indexed to identify crystal structures and orientations. The transmission electron microscope thus provides valuable microscopic and crystallographic information about materials at high resolution.
This document discusses several microtexture techniques for obtaining crystallographic information from samples, including Kossel technique, electron channeling pattern (ECP), and electron backscatter diffraction (EBSD). The Kossel technique uses X-rays to determine orientation, structure, and perfection. ECP forms diffraction patterns from tilting and rocking an electron beam. EBSD collects diffraction patterns from a tilted sample to determine orientation with high spatial resolution but a shallow interaction volume. Careful sample preparation is important to avoid surface damage for these techniques.
This document discusses various techniques for structurally characterizing nanoparticles, including transmission electron microscopy (TEM), X-ray diffraction, and simulations. TEM can be used to obtain selected area electron diffraction patterns, high resolution TEM images, and particle assembly information. X-ray diffraction can determine particle size and distributions through peak broadening and the Scherrer equation. Both techniques along with simulations are useful for analyzing structure, orientation, defects and composition of nanoparticles.
This document provides an introduction to nano-materials. It defines nano-materials as artificial semiconductor structures with dimensions on the nanometer scale, including quantum wells, wires, and dots. Electron behavior changes from plane waves in free space, to Bloch waves in bulk semiconductors, to discrete energy levels in low-dimensional nano-structures. Nano-materials are of interest because they allow tailoring of electronic and optical properties by controlling geometric confinement. Common fabrication methods include lithography and self-organized growth to achieve sizes less than 100nm for full quantum confinement effects. Nano-materials demonstrate properties like ballistic transport, tunneling, and quantized energy levels that enable applications in light sources, detectors, and electronic devices
The document summarizes research on the band structure properties of silicon carbide (SiC) using density functional theory calculations. It studies the electronic band structure, density of states, effective electron mass, and scattering mechanisms of SiC in the wurtzite crystal structure. The results show good agreement with experimental band gap values. Calculations of effective mass were performed using a 3-valley model. Scattering from piezoelectric, deformation potential, and optical phonon interactions is analyzed as a function of electron energy and temperature.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
- Fourier shell correlation (FSC) is used to estimate resolution in cryo-EM by measuring the correlation between two independent half maps in Fourier space shells.
- True resolution varies locally within cryo-EM maps and a single number does not fully describe map quality.
- Map and model validation are important to assess whether the map and model accurately represent the structure and are not affected by model bias.
Isolation of MIMO Antenna with Electromagnetic Band Gap StructureAysu COSKUN
This work represents isolation of mimo antenna system with mushroom type electromagnetic band gap structure in order to reduce mutual coupling between antennas.
Interatomic potentials are needed to model interactions between atoms and molecules in simulations. The most common approaches are semi-empirical potentials which make an educated guess about the potential energy surface and adjust parameters to experimental data. Common potentials include Lennard-Jones for non-bonded interactions and Morse for bonded interactions. However, pair potentials have limitations and fail to capture properties of metals where electrons are delocalized. Embedded-atom models provide a better description of metallic bonding. Specialized potentials are also developed for materials with directional bonding like silicon.
This document discusses basis sets and pseudopotentials used in quantum chemistry calculations. It describes Slater-type orbitals (STOs) and Gaussian-type orbitals (GTOs) as basis functions, as well as contracted basis sets that reduce the number of basis functions. It also discusses polarized, diffuse, and plane wave basis sets. Pople and Dunning basis sets are introduced as optimized contracted basis sets. Effective core potentials (ECPs) and model core potentials (MCPs) are discussed as approximations that replace core electrons with an effective potential.
Microtexture analysis provides experimental details of electron diffraction techniques used to determine crystallographic orientation and microstructure in scanning electron microscopes. Key techniques discussed include electron channeling patterns and electron backscatter diffraction. Proper specimen preparation is important for these techniques, requiring an uncompromised surface free of damage, coatings, or contamination within the shallow electron interaction volume.
Ultraviolet photoelectron spectroscopy (UPS) probes valence states with higher energy resolution than XPS due to using higher photon energies in the vacuum ultraviolet range. Two common methods for producing VUV photons are synchrotron radiation, which provides high photon flux but requires expensive facilities, and differentially pumped gas discharge lamps, which can be housed in a university lab but have limited tunability. UPS provides high surface sensitivity due to the short escape depth of photoelectrons. Angle-resolved UPS allows measurement of crystal band structure by varying the emission angle to determine momentum components parallel to the surface.
This document discusses various methods for calculating radar cross section (RCS), including the finite difference time domain method, method of moments, geometrical optics, physical optics, geometrical theory of diffraction, and physical theory of diffraction. It provides overviews and comparisons of each method, explaining their approaches and areas of applicability. The document also includes examples of RCS calculations and summaries of key points about specific methods.
This document discusses various methods for calculating radar cross section (RCS), including the finite difference time domain method, method of moments, geometrical optics, physical optics, geometrical theory of diffraction, and physical theory of diffraction. It provides overviews and comparisons of each method, explaining their approaches, assumptions, accuracy, and applicability to different target sizes and frequencies.
Similar to Rutherford Back-Scattering(RBS) Modeling Algorithms (20)
Organic electronics such as organic LEDs (OLEDs) and organic photovoltaics (OPVs) offer advantages over traditional electronics like being lightweight, flexible, and having low-cost production. The document discusses the electronic structures of organic materials used in these applications and how they enable charge transport. It reviews the state-of-the-art in OLED and OPV technologies and processing techniques like solution processing and vapor deposition. Photocrosslinking is highlighted as a method to improve device performance. Challenges in improving material properties, device efficiencies, and reducing costs are also outlined.
The document discusses metamaterials and their applications. It begins with defining metamaterials as artificially engineered materials with properties not found in nature. It then discusses techniques for achieving negative permeability and permittivity values, challenges in optical metamaterials, and applications including 3D metamaterials, slow light, cloaking, chiral metamaterials, and superlensing. The talk is divided into sections on different metamaterial topics that will be covered.
Spintronics utilizes the intrinsic spin property of electrons in addition to their charge to create new devices. Devices like giant magnetoresistance (GMR) sensors and magnetic random access memory (MRAM) make use of electron spin and its interaction with magnetism. GMR sensors detect tiny magnetic fields by measuring resistance changes between parallel and antiparallel electron spin alignments in thin magnetic layers separated by a conductor. MRAM uses magnetic tunnel junctions to store information as the orientation of magnetization, allowing for high density, non-volatile memory. Spintronic devices promise enhanced functionality, higher speeds, and lower power consumption compared to conventional electronics as devices continue shrinking to the nanoscale.
The document discusses erbium-doped fiber lasers (EDFLs). EDFLs emit light at 1.55μm, which lies in the eye-safe region of the spectrum and is preferred for long-distance fiber optic communications. They consist of an optical fiber doped with erbium ions as the gain medium, pump lasers to excite the erbium ions, and dielectric mirrors or fiber Bragg gratings to form the optical resonator. EDFLs have revolutionized fiber optic communications and next generation versions may be integrated onto single chips.
Heterostructures, HBTs and Thyristors : Exploring the "different"Shuvan Prashant
The document discusses heterostructures, heterojunction bipolar transistors (HBTs), and thyristors. It begins by explaining homojunctions and heterojuctions, how they differ in material composition and resulting energy band structures. It then describes HBTs, noting they can achieve higher speeds than bipolar junction transistors (BJTs) due to reduced injection of minority carriers into the emitter. Finally, it discusses thyristors, four-layer pnpn semiconductor devices that can operate in either conducting or blocking states, and diacs, bidirectional thyristor variants used in alternating current switching applications.
This document discusses optical solitons, which are pulses of light that propagate without changing shape due to a balance between dispersion and nonlinear effects. It covers self-phase modulation, how pulses propagate in dispersive fiber, and how solitons form under certain conditions. The document also briefly summarizes other soliton types including dark, spatial, and N-solitons. It concludes by noting that while solitons allow for virtually error-free high-speed optical communications, they remain at the prototype stage due to challenges around amplification.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
2. Motivation
• RBS analysis algorithms though accurate but
computationally intensive
• Takes a lot of time on small computers
• Rapid simulation with good assumptions can fit
the RBS spectra with reasonable accuracy
Computers are useless. They can only give you answers.
Pablo Picasso
4. Assumptions
• Sample stack of sublayers
• Sublayer uniform composition and fixed
energy loss function(E dependent only)
• Sublayer should not be too thick
• Elastic Scattering
• Screening for low energies can be incorporated
• Detector resolution Gaussian convolution
• Straggling intensive but possible
5. Formation of a brick
• Each contribution is known as a
brick
• Brick energy location energy
lost by beam after scattering on
its outward path through
different sublayers.
Yield
Energy
Area Q
eb,yb ef,yf
ef
eb
E0
6. Energy Loss Evaluation
• Geometry => Angle
• Beam Energy Loss
ef
eb
E0
)(E
da
dE
• Stopping Cross-section ε(E)
• 5th order polynomial fit from elemental data
• Bragg rule for compounds
• a - Path length into material in areal density
units
7. To calculate E(Ntsecθ)
Expand using Taylor Series
...
6
1
2
1
)0()(
0
3
3
3
0
2
2
2
0
da
Ed
a
da
Ed
a
da
dE
aEaE
Surface Approximation( Upto first order)
...)'''(')( 223
6
12
2
1
0 aaaEaE
Using the definition of ε(E) and evaluating
higher differential terms ε’ and ε’’,
)(E
da
dE
8. Energy Location
• Assuming elastic scattering,
• Eafter prop to Ebefore
• Evaluate Kinematic factors for different
elements
2
1
2
22
1
cossin1
M
M
whereK
9. Building Spectrum
• Superpose contributions from each isotope in
sublayer in the sample
• Spectrum Calculation involves
– Energy Loss evaluation in each sublayer
– Final Interpolation of the spectrum
• Shape of the brick Trapezoidal bricks may
have kinks if the sublayers are thick
• Area not accurate
• How can we solve this ?
10. Solution
• Assume parabolic top profiles
• Rutherford Scattering Cross-section for a small
solid angle
sec
0
))((Area
Nt
daaE
22
4
222
21
sin1cos
cossin
coscos
2
)(
where
E
eZZ
E
2
)(generalinnuclidesFor
CEE
orderthirdofpolynomialausing
edapproximatisE(a)where)(Area 2-
sec
0
2
Nt
daaEC
12. Virtual MCA
• Using values of eb, ef, yb, yf and Q , evaluate
the coefficients A, B and C
• Virtual MCA evaluates the expression at
boundary points of the channels and
substracts to get the yield per channel.
32
2
32
CeBeAedeheightYield
CeBeAheight
13. Computation
• Stage 1
– Calculate energy on inward path and Rutherford
Integrals prop to # of sublayers
• Stage 2
– Outward energy loss for each nuclide present at
interface
– Interface.nuclide.depth # of sublayers
• Stage 3
– Stopping cross-sections
14. Straggling
• Occurs because of the
statistical nature of
energy loss
• Energy loses
monochromaticity
and becomes
gaussian in profile
• Limiting in resolution
• Bohr’s formula used
for calculating the
amount of straggling
15. Finally,
Pros
1. Simple and fast
2. Accurate
Cons
1. Resonance calculations are
not possible
2. Nuclear reaction analysis is
not possible.
3. Screening effects are
accounted only upto first
order
4. Channeling effects