Fiber optic sensing works by measuring the backscattering of light in an optical fiber when it encounters vibration, strain, or temperature change.
|
|
Common radar suppressors only cut down on backscattering, which is when radar waves hit an object and bounce right back at the emitter.
|
|
With a technique called backscattering, the phone can make a voice call by modifying and reflecting the same waves back to the base station.
|
|
The researchers took advantage of a technique called "backscattering," where existing FM broadcasts from a local radio station are reflected and modified by simple electronics connected to an antenna made of copper tape attached to the back of the poster.
|
|
What's happening: Large-scale sensor simulation enables a fast and reliable path towards perception system development by testing thousands of scenarios under hundreds of different conditions, from the size and distribution of the puddles to the speed and direction of vehicles and environmental backscattering and absorption.
|
|
Neutron backscattering is one of several inelastic neutron scattering techniques. Backscattering from monochromator and analyzer crystals is used to achieve an energy resolution in the order of μeV. Neutron backscattering experiments are performed to study atomic or molecular motion on a nanosecond time scale.
|
|
Target strength (TS) is equal to 10 log10(σbs/(1 m2)) dB, where σbs is the differential backscattering cross section. Backscattering cross section is 4πσbs.
|
|
Operational backscattering spectrometers at reactors include IN10, IN13, and IN16B at the Institut Laue- Langevin, the High Flux Backscattering Spectrometer (HFBS) at the NIST Center for Neutron Research, the SPHERES] instrument of Forschungszentrum Jülich at FRM II and EMU at ANSTO.
|
|
There are three main Brillouin spectroscopy geometries: 90 degree scattering, backscattering, and platelet geometry.
|
|
Backscattering is the principle behind radar systems. In weather radar, backscattering is proportional to the 6th power of the diameter of the target multiplied by its inherent reflective properties, provided the wavelength is larger than the particle diameter (Rayleigh scattering). Water is almost 4 times more reflective than ice but droplets are much smaller than snow flakes or hail stones. So the backscattering is dependent on a mix of these two factors.
|
|
Backscatter in photography, showing a Brocken spectre within the rings of a glory In physics, backscatter (or backscattering) is the reflection of waves, particles, or signals back to the direction from which they came. It is usually a diffuse reflection due to scattering, as opposed to specular reflection as from a mirror, although specular backscattering can occur at normal incidence with a surface. Backscattering has important applications in astronomy, photography, and medical ultrasonography. The opposite effect is forward scatter, e.g.
|
|
This Compton backscattering produces high energy photons in the MeV to GeV range subsequently used for nuclear physics experiments.
|
|
Data were obtained during the first and second lunar days, January 12 to 23, 1968, and February 13 to 21, 1968. The alpha backscattering instrument failed to deploy properly. Mission controllers successfully used the surface soil sampler claw to push the alpha backscattering instrument into the proper position to conduct its experiments.
|
|
Rutherford backscattering spectrometry (RBS) is an analytical technique used in materials science. Sometimes referred to as high-energy ion scattering (HEIS) spectrometry, RBS is used to determine the structure and composition of materials by measuring the backscattering of a beam of high energy ions (typically protons or alpha particles) impinging on a sample.
|
|
Multiple scattering is highly analogous to diffusion, and the terms multiple scattering and diffusion are interchangeable in many contexts. Optical elements designed to produce multiple scattering are thus known as diffusers. Coherent backscattering, an enhancement of backscattering that occurs when coherent radiation is multiply scattered by a random medium, is usually attributed to weak localization. Not all single scattering is random, however.
|
|
Even for incoherent radiation, the scattering typically reaches a local maximum in the direction of backscattering. For coherent radiation, however, the peak is two times higher. Coherent backscattering is very difficult to detect and measure for two reasons. The first is fairly obvious, that it is difficult to measure the direct backscatter without blocking the beam, but there are methods for overcoming this problem.
|
|
Coherent backscattering has its origin in the interference between direct and reverse paths in the backscattering direction. When a multiply scattering medium is illuminated by a laser beam, the scattered intensity results from the interference between the amplitudes associated with the various scattering paths; for a disordered medium, the interference terms are washed out when averaged over many sample configurations, except in a narrow angular range around exact backscattering where the average intensity is enhanced. This phenomenon, is the result of many sinusoidal two-waves interference patterns which add up. The cone is the Fourier transform of the spatial distribution of the intensity of the scattered light on the sample surface, when the latter is illuminated by a point-like source.
|
|
This phenomenon is typical of any coherent wave which is multiple scattered. It is typically discussed for light waves, for which it is similar to the weak localization phenomenon for electrons in disordered semi-conductors and often seen as the precursor to Anderson (or strong) localization of light. Weak localization of light can be detected since it is manifested as an enhancement of light intensity in the backscattering direction. This substantial enhancement is called the cone of coherent backscattering.
|
|
The total acoustic energy backscattered by the school or aggregation is integrated together, and this total is divided by the (previously determined) backscattering coefficient of a single animal, giving an estimate of the total number.
|
|
The enhanced backscattering relies on the constructive interference between reverse paths. One can make an analogy with a Young's interference experiment, where two diffracting slits would be positioned in place of the "input" and "output" scatterers.
|
|
The detection of a chipless tag in noisy environments is much more difficult in chipless than in UHF RFID due to the absence of modulation in time, that is, the absence of two different states in the backscattering signal.
|
|
Anticrepuscular rays are dimmer than crepuscular rays because backscattering is less than forward scattering. Anticrepuscular rays can be continuous with crepuscular rays, curving across the whole sky in great circles.Lynch, D. K., & Livingston, W. (1995). Color and light in nature.
|
|
An event near the fiber generates an acoustic wave that affects the optical fiber by changing the phases of the backscattering centers. An analysis of such signals can reveal their impact on the sensor and monitor located near fiber objects.
|
|
The photelectron scattering amplitude in the low energy range (5-200 eV) of the photoelectron kinetic energy become much larger so that multiple scattering events become dominant in the XANES (or NEXAFS) spectra. The wavelength of the photoelectron is dependent on the energy and phase of the backscattered wave which exists at the central atom. The wavelength changes as a function of the energy of the incoming photon. The phase and amplitude of the backscattered wave are dependent on the type of atom doing the backscattering and the distance of the backscattering atom from the central atom.
|
|
Another lidar technique for atmospheric remote sensing has emerged. It is based on Scheimpflug principle, referred to as Scheimpflug lidar (slidar).Liang Mei, Mikkel Brydegaard, Continuous-wave differential absorption lidar, Laser and Photonics Reviews 9, 629-636 (2015) "The implication of the Scheimpflug principle is that when a laser beam is transmitted into the atmosphere, the backscattering echo of the entire illuminating probe volume is still in focus simultaneously without diminishing the aperture as long as the object plane, image plane and the lens plane intersect with each other". A two dimensional CCD/CMOS camera is used to resolve the backscattering echo of the transmitted laser beam.
|
|
Caduff, R., Schlunegger, F., Kos, A., & Wiesmann, A. (2015). "A review of terrestrial radar interferometry for measuring surface change in the geosciences". Earth Surface Processes and Landforms, 40(2), 208–228. SAR interferometry is a technology utilizing multiple SAR images recording the backscattering of microwave signal.
|
|
During descent, pressure, temperature and photometric measurements were made, as well as backscattering and multi-angle scattering (nephelometer) measurements of cloud density. It was discovered that the clouds of Venus are formed in three distinct layers. On October 25, Venera 10 arrived and carried out a similar program of study.
|
|
On November 24, 1967, the spacecraft was shut down for the two-week lunar night. Contact was made on December 14, 1967, but no useful data was obtained. Lunar soil surveys were completed using photographic and alpha particle backscattering methods. A similar instrument, the APXS, was used onboard several Mars missions.
|
|
Singwi and Sjölander (1960) pointed out the close relation to incoherent neutron scattering. With the invention of backscattering spectrometers, it became possible to measure the Lamb–Mössbauer factor as a function of the wavenumber (whereas Mössbauer spectroscopy operates at a fixed wavenumber). Subsequently, the term elastic incoherent structure factor became more frequent.
|
|
For this reason, most implantation is carried out a few degrees off-axis, where tiny alignment errors will have more predictable effects. Ion channelling can be used directly in Rutherford backscattering and related techniques as an analytical method to determine the amount and depth profile of damage in crystalline thin film materials.
|
|
In 1987-1990, he was also head of the laboratory of the Vernadsky Institute of Geochemistry and Analytic Chemistry. In 1993, he defended his thesis of Doctor of Sciences on the topic "Backscattering of non-polarized light by randomly inhomogeneous surfaces"Бакіров В. С. (ред.). Шкуратов Юрій Григорович // Професори Харківського національного університету імені В. Н. Каразіна. Біобібліографічний довідник.
|
|
Multiplying this fraction by the density of the material when amorphous then also gives an estimate for the concentration of displaced atoms. The energy at which the increased backscattering occurs can also be used to determine the depth at which the displaced atoms are and a defect depth profile can be built up as a result.
|
|
Values less than 90° represent backscattering; values greater than 90° represent forward scattering. For some objects, such as the Moon (see lunar phases), Venus and Mercury the phase angle (as seen from the Earth) covers the full 0-180° range. The superior planets cover shorter ranges. For example, for Mars the maximum phase angle is about 45°.
|
|
Aggregation processes in strongly scattering systems have been studied with transmittance, backscattering techniques or diffusing-wave spectroscopy. Single particle counting. This technique offers excellent resolution, whereby clusters made out of tenths of particles can be resolved individually. The aggregating suspension is forced through a narrow capillary particle counter and the size of each aggregate is being analyzed by light scattering.
|
|
The two-gaussian model parameters, including the development process, can be determined experimentally by exposing shapes for which the Gaussian integral is easily solved, i.e. donuts, with increasing dose and observing at which dose the center resist clears or does not clear. A thin resist with a low electron density will reduce forward scattering. A light substrate (light nuclei) will reduce backscattering.
|
|
If the slope of the graph is steep, then power loss is high. If the slope is gentle, then optical fiber has a satisfactory loss characteristic. The loss measurement by the backscattering method allows measurement of a fiber optic cable at one end without cutting the optical fiber hence it can be conveniently used for the construction and maintenance of optical fibers.
|
|
The effect of electron–electron interactions within the dot region is taken into account in the Coulomb blockade regime or in the Kondo regime. In the former case charge transport is quantized even in the case of small backscattering. Deviation from the exact quantized value is related to dissipation. In the Kondo regime, as the temperature is lowered, the pumping effect is modified.
|
|
Typically, light is reflected via backscattering, as opposed to pure reflection one might find with a mirror. Different types of scattering are used for different lidar applications: most commonly Rayleigh scattering, Mie scattering, Raman scattering, and fluorescence. Suitable combinations of wavelengths can allow for remote mapping of atmospheric contents by identifying wavelength-dependent changes in the intensity of the returned signal.
|
|
Happer, G. J. MacDonald, C. E. Max, and F. J. Dyson, "Atmospheric-turbulence compensation by resonant optical backscattering from the sodium layer in the upper atmosphere," J. Opt. Soc. Am. A 11, 263-276 (1994): abstract. Happer was chairman of the steering committee for JASON, 1987–1990. Also, he has had numerous other assignments: trustee of the MITRE Corporation, the Richard Lounsbery Foundation and the Marshall Institute.
|
|
Sojourner takes its APXS measurement of the Yogi Rock. Some of the alpha particles of a defined energy are backscattered to the detector if they collide with an atomic nucleus. The physical laws for Rutherford backscattering in an angle close to 180° are conservation of energy and conservation of linear momentum. This makes it possible to calculate the mass of the nucleus hit by the alpha particle.
|
|
In most cases, medium heavy ion beams, typically 36Cl ions, have been used for ERDA so far with energies around 30 MeV. Depth resolution and element profiling of thin films has been greatly advanced using elastic recoil detection analysis. Figure 2, on the left, depicts the interaction of a heavy ion beam striking the sample atoms and the resulting backscattering and recoil ions.Elliott, Lee.
|
|
The copper coating and the glass substrate was also identified. Not only is ERDA is also coupled to Rutherford backscattering spectrometry, which is a similar process to ERDA. Using a solid angle of 7.5 mrs, recoils can be detected for this specific analysis of TiNxOy-Cu. It is important when designing an experiment to always consider the geometry of the system as to achieve recoil detection.
|
|
An early Raman spectrum of benzene published by Raman and Krishnan. Schematic of a dispersive Raman spectroscopy setup in a 180° backscattering arrangement. Modern Raman spectroscopy nearly always involves the use of lasers as an exciting light source. Because lasers were not available until more than three decades after the discovery of the effect, Raman and Krishnan used a mercury lamp and photographic plates to record spectra.
|
|
The backscattering method is also employed in fiber optics applications to detect optical faults. Light propagating through a fiber optic cable gradually attenuates due to Rayleigh scattering. Faults are thus detected by monitoring the variation of part of the Rayleigh backscattered light. Since the backscattered light attenuates exponentially as it travels along the optical fiber cable, the attenuation characteristic is represented in a logarithmic scale graph.
|
|
The word channelling in ECCI, and, similarly, in electron channelling patterns refers to diffraction of the electron beam on its way in the sample. With enough spatial resolution, very small crystal imperfections would change the phase of the incident electron wave-function, and this, in turn, would be reflected in the backscattering probability, showing up as contrast (sharp change in backscattered intensity) close to a dislocation.
|
|
Light elements absorb more energy of the alpha particle, while alpha particles are reflected by heavy nuclei nearly with the same energy. The energy spectrum of the scattered alpha particle shows peaks from 25% up to nearly 100% of the initial alpha particles. This spectrum makes it possible to determine the composition of the sample, especially for the lighter elements. The low backscattering rate makes prolonged irradiation necessary, approximately 10 hours.
|
|
This creates a healthy environment with myofibroblasts and extracellular matrix. This is known as light backscattering or subepithial haze. When there is injury to an epithelial cell heptotaxis occurs, which is highly influenced by the cell's velocity, which is in turn influenced by direction of cell motility. Cells migrate easily and quickly in packs, so when one cell moves the rest follow in response to the gradient and initial cell movement.
|
|
Neutron backscattering was proposed by Heinz Maier- Leibnitz in 1966,H. Maier-Leibnitz: Grundlagen für die Beurteilung von Intensitäts- und Genauigkeitsfragen bei Neutronenstreumessungen, Nukleonik 8, 61 (1966). and realized by some of his students in a test setup at the research reactor FRM I in Garching bei München, Germany. Following this successful demonstration of principle, permanent spectrometers were built at Forschungszentrum Jülich and at the Institut Laue-Langevin (ILL).
|
|
Measurement principle of multiple light scattering coupled with vertical scanning Multiple light scattering coupled with vertical scanning is the most widely used technique to monitor the dispersion state of a product, hence identifying and quantifying destabilisation phenomena. It works on concentrated dispersions without dilution. When light is sent through the sample, it is backscattered by the particles / droplets. The backscattering intensity is directly proportional to the size and volume fraction of the dispersed phase.
|
|
These are small enough to pass through the capillaries and are used to increase the contrast in the left ventricle, improving the visualization of its walls. The drop in density on the interface between the gas in the bubble and the surrounding liquid strongly scatters and reflects the ultrasound back to the probe. This process of backscattering gives the liquid with these bubbles a high signal, which can be seen in the resulting image.
|
|
Strain-fields (bright) around ion-track cores in FeCr2O4. Ion tracks are damage-trails created by swift heavy ions penetrating through solids, which may be sufficiently-contiguous for chemical etching in a variety of crystalline, glassy, and/or polymeric solids. They are associated with cylindrical damage-regions several nanometers in diameter and can be studied by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS) or gas permeation.
|
|
Metallic modes bounding semiconducting regions of opposite-sign mass is a hallmark of a topological phase and display much the same physics as topological insulators. If the mass in graphene can be controlled, electrons can be confined to massless regions by surrounding them with massive regions, allowing the patterning of quantum dots, wires and other mesoscopic structures. It also produces one-dimensional conductors along the boundary. These wires would be protected against backscattering and could carry currents without dissipation.
|
|
The counting of charges collected per unit time is impacted by two error sources: 1) the emission of low-energy secondary electrons from the surface struck by the incident charge and 2) backscattering (~180 degree scattering) of the incident particle, which causes it to leave the collecting surface, at least temporarily. Especially with electrons, it is fundamentally impossible to distinguish between a fresh new incident electron and one that has been backscattered or even a fast secondary electron.
|
|
The technique communicates via backscattering, reflecting incoming radio waves sent from a separate device. The technique is similar to contactless RFID chip cards although unlike such cards, the new technique does not require a special device to read the signal. The project effectively decoupled the analog and the digital radio signals. Power- intensive functions – like producing a signal at a specific frequency are assigned to a single device in the network that is plugged into the grid.
|
|
She has worked on strain relaxation in lattice-mismatched semiconductor heterostructures, diffusion barriers and electrical contacts for silicon and III-V semiconductor based devices, epitaxial growth and nucleation, and electron transport through thin films and interfaces. Her work on characterization tools including electron microscopy, Rutherford backscattering, x-ray diffraction, and scanning probe microscopy. She is a Fellow of the Institute of Physics and is the author of over 130 journal papers and conference proceedings, as shown in the Web of Science.
|
|
Anticrepuscular rays, or antisolar rays, are meteorological optical phenomena similar to crepuscular rays, but appear opposite of the Sun in the sky. Anticrepuscular rays are essentially parallel, but appear to converge toward the antisolar point, the vanishing point, due to a visual illusion from linear perspective. Anticrepuscular rays are most frequently visible around sunrise or sunset. This is because the atmospheric light scattering that makes them visible (backscattering) is larger for low angles to the horizon than most other angles.
|
|
In physics, coherent backscattering is observed when coherent radiation (such as a laser beam) propagates through a medium which has a large number of scattering centers (such as milk or a thick cloud) of size comparable to the wavelength of the radiation. Propagation of two rays in a random medium. Since one can be obtained from the other by time inversion, they interfere coherently when the angle θ goes to zero. The waves are scattered many times while traveling through the medium.
|
|
The ETH Laboratory of Ion Beam Physics (LIB) is a physics laboratory located in Science City. It specializes in accelerator mass spectrometry (AMS) and the use of ion beam based techniques with applications in archeology, earth sciences, life sciences, material sciences and fundamental physics. An example of such application is the tracing of isotopes and the detection of rare radionuclides with radiocarbon dating and the use of techniques such as Rutherford backscattering spectrometry or elastic recoil detection. The LIB is developing the next generation of AMS machines.
|
|
Ultra-thin silicon nitride windows have been introduced, together with dramatic simplifications in the design, which have been demonstrated to be nearly as good as more complex designs for low energy ERD. These detectors have also been implemented in heavy ion Rutherford Backscattering Spectrometry. Figure 7 shows the Gas Ionization chamber with Isobutane as the detector gas. Figure 7: Gas Ionization Chamber showing the positive charges migrating toward the cathode and the negatively charged ions migrating toward the sub divided anode through a Frisch Grid.
|
|
Elastic Recoil Detection Analysis (ERDA), also referred to as forward recoil scattering (or, contextually, spectrometry), is an Ion Beam Analysis technique in materials science to obtain elemental concentration depth profiles in thin films. This technique is known by several different names. These names are listed below. In the technique of ERDA, an energetic ion beam is directed at a sample to be characterized and (as in Rutherford backscattering) there is an elastic nuclear interaction between the ions of beam and the atoms of the target sample.
|
|
After the war, he used and modified captured V-2 rockets to make measurements on atmospheric cosmic rays, leading him to propose that most gamma rays in the atmosphere were not the cosmic rays themselves, but were rather due to Compton backscattering. In 1952, he became a faculty member at University of Minnesota. In 1954, he moved to Illinois to work at the Argonne National Laboratory, until he retired in 1981. In 1970, he became editor of the Journal of Applied Physics and Applied Physics Letters.
|
|
These errors can originate either from the electron optical control hardware or the input data that was taped out. As might be expected, larger data files are more susceptible to data-related defects. Physical defects are more varied, and can include sample charging (either negative or positive), backscattering calculation errors, dose errors, fogging (long-range reflection of backscattered electrons), outgassing, contamination, beam drift and particles. Since the write time for electron beam lithography can easily exceed a day, "randomly occurring" defects are more likely to occur.
|
|
Bru, L. Brunel, H. Buron, I. Cayré, X. Ducarre, A. Fraux, O. Mengual, G. Meunier, A. de Sainte Marie and P. Snabre Particle sizing and characterization Ed T. Provder and J. Texter (2004) It works on concentrated dispersions without dilution. When light is sent through the sample, it is back scattered by the particles. The backscattering intensity is directly proportional to the size and volume fraction of the dispersed phase. Therefore, local changes in concentration (sedimentation) and global changes in size (flocculation, aggregation) are detected and monitored.
|
|
The same surface can appear rough in VNIR may appear smooth in microwave, similar to what we perceive when we use a meter rule to measure roughness where surface fluctuation are in cm-scale. As grain size decreases, surface roughness increases and hence overall reflectance increases as diffuse reflection, instead of specular reflection, dominates. Specular reflection by smooth surface, for example calm water, gives little backscattering and hence appear dark. As an example, ice is mostly transparent in a large piece but becomes highly reflective when smashed into small grains.
|
|
Mengual, G. Meunier, I. Cayre, K. Puech, P. Snabre, Colloids and Surfaces A: Physicochemical and Engineering Aspects 152 (1999) 111–123P. Bru, L. Brunel, H. Buron, I. Cayré, X. Ducarre, A. Fraux, O. Mengual, G. Meunier, A. de Sainte Marie and P. Snabre Particle sizing and characterisation Ed T. Provder and J. Texter (2004) It works on any concentrated dispersions without dilution, including foams. When light is sent through the sample, it is backscattered by the bubbles. The backscattering intensity is directly proportional to the size and volume fraction of the dispersed phase.
|
|
The functional operation and accuracy of Doppler velocity sensors is affected by many factors, including aircraft velocity, attitude and altitude above terrain. It is also affected by environmental factors, including the type of terrain the radar is illuminating, and precipitation in the atmosphere. As the aircraft moves, the backscattering coefficient changes within the beam width, and this causes a shift and some skewing of the Doppler spectrum, and hence an error in the measurement of velocity. A major limitation of using DVSs for navigation is that they typically suffer from accumulated error.
|
|
However, there has been a surge in studies of thin layers within the past two decades due to major advances in technology and instrumentation. Phytoplankton are often measured by optical instruments that can detect fluorescence such as LIDAR, and zooplankton are often measured by acoustic instruments that can detect acoustic backscattering such as ABS. These extraordinary concentrations of plankton have important implications for many aspects of marine ecology (e.g., phytoplankton growth dynamics, zooplankton grazing, behaviour, environmental effects, harmful algal blooms), as well as for ocean optics and acoustics.
|
|
The radar transmits an electromagnetic pulse along each of the antenna's pointing directions. A UHF profiler includes subsystems to control the radar's transmitter, receiver, signal processing, and Radio Acoustic Sounding System (RASS), if provided, as well as data telemetry and remote control. The duration of the transmission determines the length of the pulse emitted by the antenna, which in turn corresponds to the volume of air illuminated (in electrical terms) by the radar beam. Small amounts of the transmitted energy are scattered back (referred to as backscattering) toward and received by the radar.
|
|
In 1965 Holliday left Austin to develop the Tracor facility in San Diego and began his doctorate in applied physics at the University of California, San Diego. In San Diego Holliday began his study in acoustics for which he is known. His study of transient flow in natural gas pipelines led to the publication of a textbook which is still used as a standard reference. In the 1970s Holliday began testing a revolutionary technique for the detection and size measurement of zooplankton in thin layers involving multi-frequency backscattering.
|
|
The scattering was primarily forward, into the crystal, as opposed to backscattering towards the light source. By placing a reflector on the far side of the crystal, the incident light could be turned on or off electrically, creating what Heilmeier dubbed dynamic scattering. In 1965 Joseph Castellano and Joel Goldmacher, organic chemists, sought crystals that remained in the fluid state at room temperature. Within six months they had found a number of candidates, and with further development, RCA was able to announce the first liquid crystal displays in 1968.
|
|
Gold nanoparticles have been recently used as a basis for a count of atomic species, especially with studying the content of cancer cells. Ion beam analysis is a great way to count the amount of atomic species per cell. Scientists have found an effective way to make accurate quantitative data available by using ion beam analysis in conjunction with elastic backscattering spectrometry (EBS). The researchers of a gold nanoparticle study were able to find much greater success using ion beam analysis in comparison to other analytical techniques, such as PIXE or XRF.
|
|
This led to hot spots on the pellet which were imprinted into the imploding plasma, seeding Rayleigh–Taylor instabilities and thereby mixing the plasma so the center did not collapse uniformly.Moody et all, "Beam smoothing effects on stimulated Raman and Brillouin backscattering in laser-produced plasmas", Journal of Fusion Energy, Vol. 12, No. 3, September 1993, , pp. 323-330 Nevertheless, Nova remained a useful instrument even in its original form, and the main target chamber and beamlines were used for many years even after it was modified as outlined below.
|
|
Many inelastic studies that use normal time-of-flight (TOF) or backscattering spectrometers rely on the huge incoherent neutron scattering cross section of protons. The scattering signal is dominated by the corresponding contribution, which represents the (average) self-correlation function (in time) of the protons. For NSE spin incoherent scattering has the disadvantage that it flips the neutron spins during scattering with a probability of 2/3. Thus converting 2/3 of the scattering intensity into "non- polarized" background and putting a factor of -1/3 in front of the cos-Fourier integral contribution pertaining the incoherent intensity.
|
|
In addition, channeling of ions can also be used to analyze a crystalline sample for lattice damage.Feldman et al. (1982) If atoms within the target are displaced from their crystalline lattice site, this will result in a higher backscattering yield in relation to a perfect crystal. By comparing the spectrum from a sample being analyzed to that from a perfect crystal, and that obtained at a random (non-channeling) orientation (representative of a spectrum from an amorphous sample), it is possible to determine the extent of crystalline damage in terms of a fraction of displaced atoms.
|
|
Real aperture radar (RAR) is a form of radar that transmits a narrow angle beam of pulse radio wave in the range direction at right angles to the flight direction and receives the backscattering from the targets which will be transformed to a radar image from the received signals. Usually the reflected pulse will be arranged in the order of return time from the targets, which corresponds to the range direction scanning. The resolution in the range direction depends on the pulse width. The resolution in the azimuth direction is identical to the multiplication of beam width and the distance to a target.
|
|
The small size of the nucleus explained the small number of alpha particles that were repelled in this way. Rutherford showed, using the method outlined below, that the size of the nucleus was less than about (how much less than this size, Rutherford could not tell from this experiment alone; see more below on this problem of lowest possible size). As a visual example, Figure 1 shows the deflection of an alpha particle by a nucleus in the gas of a cloud chamber. Rutherford scattering is now exploited by the materials science community in an analytical technique called Rutherford backscattering.
|
|
The core holes thus created can then be filled by nonradiative decay of a higher-lying electron and communication of energy to yet another electron, which can then escape from the surface (Auger emission). The photoabsorption can therefore be monitored by direct detection of these Auger electrons to the total photoelectron yield. The absorption coefficient versus incident photon energy contains oscillations which are due to the interference of the backscattered Auger electrons with the outward propagating waves. The period of this oscillations depends on the type of the backscattering atom and its distance from the central atom.
|
|
First operation of lidar on Mars; telescope (black tube) and laser window (smaller opening in foreground) can be seen. The vertical-pointing lidar was capable of detecting multiple types of backscattering (for example Rayleigh scattering and Mie Scattering), with the delay between laser pulse generation and the return of light scattered by atmospheric particles determining the altitude at which scattering occurs. Additional information was obtained from backscattered light at different wavelengths (colors), and the Phoenix system transmitted both 532 nm and 1064 nm. Such wavelength dependence may make it possible to discriminate between ice and dust, and serve as an indicator of the effective particle size.
|
|
LEIS is closely related to both medium-energy ion scattering (MEIS) and high-energy ion scattering (HEIS, known in practice as Rutherford backscattering spectroscopy, or RBS), differing primarily in the energy range of the ion beam used to probe the surface. While much of the information collected using LEIS can be obtained using other surface science techniques, LEIS is unique in its sensitivity to both structure and composition of surfaces. Additionally, LEIS is one of a very few surface-sensitive techniques capable of directly observing hydrogen atoms, an aspect that may make it an increasingly more important technique as the hydrogen economy is being explored.
|
|
There are two basic principles of measurement for distributed sensing technology, OTDR (Optical Time Domain Reflectometry) and OFDR (Optical Frequency Domain Reflectometry). For Distributed Temperature Sensing often a Code Correlation technology Method and apparatus for performing optical time domain reflectometry , PatentOPTICAL REFLECTOMETRY ANALYSIS BASED ON FIRST ORDER AND SECOND ORDER SCATTER SIGNALS , Patent is employed which carries elements from both principles. OTDR was developed more than 20 years ago and has become the industry standard for telecom loss measurements which detects the—compared to Raman signal very dominant—Rayleigh backscattering signals. The principle for OTDR is quite simple and is very similar to the time of flight measurement used for radar.
|
|
The concept of the surface-barrier particle detector that Mayer first developed served as a cornerstone for the rapid development of numerous research areas. Because of its small size and compactness, the surface-barrier particle detector almost immediately started replacing many of the cumbersome detectors in use at that time, i.e. magnetic spectrometers and ionization chambers, revolutionizing low energy nuclear structure physics almost overnight. These semiconductor spectrometers led to the practical development of many modern materials analysis techniques that have wide spread use today, such as X-ray fluorescence and ion beam analysis of materials, including Rutherford backscattering, ion channeling, and X-ray spectrometry based on alpha particle sources.
|
|
The proximity effect in electron beam lithography (EBL) is the phenomenon that the exposure dose distribution, and hence the developed pattern, is wider than the scanned pattern, due to the interactions of the primary beam electrons with the resist and substrate. These cause the resist outside the scanned pattern to receive a non-zero dose. Important contributions to weak-resist polymer chain scission (for positive resists) or crosslinking (for negative resists) come from electron forward scattering and backscattering. The forward scattering process is due to electron-electron interactions which deflect the primary electrons by a typically small angle, thus statistically broadening the beam in the resist (and further in the substrate).
|
|
Collisions of atoms are elastic, for example Rutherford backscattering. A useful special case of elastic collision is when the two bodies have equal mass, in which case they will simply exchange their momenta. The molecules—as distinct from atoms—of a gas or liquid rarely experience perfectly elastic collisions because kinetic energy is exchanged between the molecules’ translational motion and their internal degrees of freedom with each collision. At any instant, half the collisions are, to a varying extent, inelastic collisions (the pair possesses less kinetic energy in their translational motions after the collision than before), and half could be described as “super-elastic” (possessing more kinetic energy after the collision than before).
|
|
B denotes the precession field strength, λ the (average) neutron wavelength and Δv the neutron velocity change upon scattering at the sample. The main reason for using NSE is that by the above means it can reach Fourier times of up to many 100ns, which corresponds to energy resolutions in the neV range. The closest approach to this resolution by a spectroscopic neutron instrument type, namely the backscattering spectrometer (BSS), is in the range of 0.5 to 1 μeV. The spin- echo trick allows to use an intense beam of neutrons with a wavelength distribution of 10% or more and at the same time to be sensitive to velocity changes in the range of less than 10−4.
|
|
Defect formation in gallium arsenide was studied during implantation of N, Al, P, As, and Sb ions under conditions of controlled energy density released in cascades of atomic collisions at temperatures from 40 K to several hundred degrees Celsius with ion current density from hundredths to units of μA / cm2. Using the Rutherford backscattering (RBS), the distribution profiles of the implanted As, Sb were established using the 27Al (p,γ)28Si resonance nuclear reaction of aluminum profiles in gallium arsenide. These results, as well as the results of studies of the modification of the catalytic properties of nickel electrodes for water alkaline electrolysis for the production of hydrogen, formed the basis for a doctoral dissertation.
|
|
A ring laser gyro splits a beam of laser light into two beams in opposite directions through narrow tunnels in a closed circular optical path around the perimeter of a triangular block of temperature-stable Cervit glass with reflecting mirrors placed in each corner. When the gyro is rotating at some angular rate, the distance traveled by each beam becomes different—the shorter path being opposite to the rotation. The phase shift between the two beams can be measured by an interferometer and is proportional to the rate of rotation (Sagnac effect). In practice, at low rotation rates the output frequency can drop to zero as the result of backscattering causing the beams to synchronise and lock together.
|
|
Shkuratov made a defining contribution to the theory of light scattering by regolith, in particular, he created the theory of coherent amplification during backscattering. He studied Moon using data from the Galileo, Clementine, and Lunar Prospector spacecraft. He worked in the scientific group for processing polarimetric observations of Mars with the Hubble Space Telescope and in the group for data analysis of the European space project for lunar exploration Smart-1. Worked on the development of an unrealized Ukrainian scientific mission for up to MoonShkuratov Y. G., Lytvynenko L. M., Shulga V. M., Yatskiv Y. S., Vidmachenko A. P., Kislyulk V. S. Objectives of a prospective Ukrainian orbiter mission to the moon // Advances in Space Research.
|
|
Relaxations can be detected by a similar procedure with the sample tilted so the ion beam is incident at an angle selected so that first-layer atoms should block backscattering at a diagonal; that is, from atoms which are below and displaced from the blocking atom. A higher-than-expected backscattered yield will indicate that the first layer has been displaced relative to the second layer, or relaxed. Adsorbate materials will be detected by their different composition, changing the position of the surface peak relative to the expected position. RBS has also been used to measure processes which affect the surface differently from the bulk by analyzing changes in the channeled surface peak.
|
|
A confirmation of the photonic jet in the microwave scale, observing the backscattering enhancement that occurred when metallic particles were introduced in the focus area. A measurable enhancement of the backscattered light in the visible range was obtained when a gold nanoparticle was placed inside the photonic nanojet region produced by a dielectric microsphere with a 4.4 μm diameter. A use of nanojets produced by transparent microspheres in order to excite optical active materials, under upconversion processes with different numbers of excitation photons, has been analyzed as well. Monodisperse glass microspheres have high sphericity and a very tight particle size distribution, often with CV<10% and specification of >95% of particles in size range.
|
|
In this technique, multiple detectors are used: at backscattering angles to detect heavier elements by RBS and forward (recoil) detector to simultaneously detect the recoiled hydrogen. The recoil detector for LI-ERDA typically has a “range foil” which is typically a Mylar foil placed in front of the detector for blocking scattered incident ions but allow lighter recoiling target atoms to pass through to the detector. Usually a 10 µm thick Mylar foil is able to completely stop 2.6 MeV He+ ions but allows the recoiled protons to go through with a low energy loss. HI-ERDA is more widely used compared to LI-ERDA because it can be used to study a lot more variety of elements compared to LI-ERDA.
|
|
Robert Alfano is an Italian-American experimental physicist. He is a Distinguished Professor of Science and Engineering at the City College and Graduate School of New York of the City University of New York, where he is also the founding Director of the Institute for Ultrafast Spectroscopy and Lasers (1982). He is a pioneer in the fields of Biomedical Imaging and Spectroscopy, Ultrafast lasers and optics, tunable lasers, semiconductor materials and devices, optical materials, biophysics, nonlinear optics and photonics; he has also worked extensively in nanotechnology and coherent backscattering. His discovery of the white-light supercontinuum laser is at the root of optical coherence tomography, which is breaking barriers in ophthalmology, cardiology, and oral cancer detection (see "Better resolution with multibeam OCT," page 28) among other applications.
|
|
The High Intensity Gamma-Ray Source (HIGS) produces gamma-rays by means of Compton backscattering. This occurs when photons from a Free-electron laser collide with accelerated Electrons, producing a beam of high energy photons with a very precise energy and a high degree of polarization. The gamma-ray beams can be produced with energies ranging from 1-100 MeV with a maximum intensity of 1000 \gamma/s/eV, making HIGS the highest intensity accelerator driven gamma-ray source in the world. Research at HIGS can be broken broadly into two groups: Nuclear Structure and Nuclear Astrophysics, with reactions such as (\gamma, \gamma'), (\gamma, n), and (\gamma, \alpha), along with Low-energy QCD, with studies on Compton scattering and Photo-Pion production.
|
|
Radical materials advances can drive the creation of new products or even new industries, but stable industries also employ materials scientists to make incremental improvements and troubleshoot issues with currently used materials. Industrial applications of materials science include materials design, cost-benefit tradeoffs in industrial production of materials, processing methods (casting, rolling, welding, ion implantation, crystal growth, thin-film deposition, sintering, glassblowing, etc.), and analytic methods (characterization methods such as electron microscopy, X-ray diffraction, calorimetry, nuclear microscopy (HEFIB), Rutherford backscattering, neutron diffraction, small-angle X-ray scattering (SAXS), etc.). Besides material characterization, the material scientist or engineer also deals with extracting materials and converting them into useful forms. Thus ingot casting, foundry methods, blast furnace extraction, and electrolytic extraction are all part of the required knowledge of a materials engineer.
|
|
CODAR operates using sky transmission of waves in the high frequency (HF) band (3–30 MHz), as electromagnetic waves in this band have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface.J. D. Paduan, L. Washburn, High-Frequency Radar Observations of Ocean Surface Currents, Annual Review of Marine Science, 2012 According as the customer necessities, it can be used in single or multi-frequency mode. As the ocean has a rough surface, when a high frequency signal reaches the ocean surface, a portion of the incident energy is scattered back towards the source and the receiver measures the reflected signal. This backscattering (or reflection) produces an energy spectrum at the receiver, even if the energy source is single-frequency, because of the shape and motion of the sea surface.
|
|
The ALADIN instrument (Atmospheric Laser Doppler Instrument) is a direct detection ultraviolet laser lidar consisting of three major elements: a transmitter, a combined Mie and Rayleigh backscattering receiver assembly, and a Cassegrain telescope with a diameter. The transmitter architecture is based on a 150 mJ pulsed diode-pumped Nd:YAG laser, frequency-tripled to provide 60 mJ pulses of ultraviolet light at 355 nm. This frequency was chosen because of the increased Rayleigh scattering in the ultraviolet region of the spectrum, and because it is eye-safe at distances greater than several hundred metres.Sandip Pal, Andreas Behrendt, Marcus Radlach, Thorsten Schaberl, and Volker Wulfmeyer, Eye-Safe Scanning Aerosol Lidar at 355 nm The Mie receiver consists of a Fizeau interferometer with a resolution of 100 MHz (equivalent to 18 m/s).
|
|
Determination of a material's surface reconstruction requires a measurement of the positions of the surface atoms that can be compared to a measurement of the bulk structure. While the bulk structure of crystalline materials can usually be determined by using a diffraction experiment to determine the Bragg peaks, any signal from a reconstructed surface is obscured due to the relatively tiny number of atoms involved. Special techniques are thus required to measure the positions of the surface atoms, and these generally fall into two categories: diffraction-based methods adapted for surface science, such as low-energy electron diffraction (LEED) or Rutherford backscattering spectroscopy, and atomic-scale probe techniques such as scanning tunneling microscopy (STM) or atomic force microscopy. Of these, STM has been most commonly used in recent history due to its very high resolution and ability to resolve aperiodic features.
|
|
If the echo from the target is received while the transmitter is still sending, the echo will be swamped by the transmitted pulse backscattering off local sources. For instance, a radar with a pulse width of 1 µs would not be able to see returns from a target less than 150 m away, because the radar signal travelling at the speed of light would cover the round trip distance of 300 m before that 1 µs interval had passed. In the case of ASV this was not a problem; aircraft would not approach a ship on the surface more closely than its altitude of perhaps a few thousand feet, so a longer pulse width was fine. But in the AI role, the minimum range was pre- defined by the pilot's eyesight, at 300 m or less for night interception, which demanded sub-microsecond pulse widths.
|
|
Tashlykov paid much attention to the training of scientific and pedagogical specialists, forming their interest in science from the student years. The monograph "Non-destructive Analysis of Solids Surfaces by Ion Beams", published in the “Universitetskoye” publishing house, is used as a textbook for reading special courses at the Departments of Semiconductor Physics and Solid State Physics at the BSU. The developed method of resonance nuclear reactions for layer analysis of light impurities was used in a laboratory workshop on the "Backscattering method and nuclear reactions in elemental analysis of substance" for the training of students at the Kharkiv State University, as well as in similar works at the D.V. Scobeltsyn Research Institute of Nuclear Physics of Moscow State University, at the Research Institute of Physics of Rostov State University. A student research laboratory "PHYSMATING" fruitfully worked under his scientific guidance at the Physics and Mathematics Faculty of the BSPU named after M. Tank.
|
|
Mayer played a pivotal role in the application of particle detectors to the fledgling field of ion beam analysis (often referred to as Rutherford Backscattering Spectrometry or RBS) and the development of this field into a major analytical tool. He went on to define many of the advances in thin film science of the 1970s and 80s, including thin film reactions and kinetics (especially of metal silicides), solid phase regrowth of semiconductors, ion beam mixing for the formation of metastable alloys, implantation disorder and impurity location in semiconductors, and the study of thin dielectric films. In the rapid surge of industrial interest in ion implantation of Si, starting around 1965, Mayer and his coworkers used ion channeling to understand defect production during dopant ion implantation into Si, the recovery of this damage, and the activation of dopants during subsequent anneals, thereby making ion implantation a viable tool for the production of integrated circuits. In 1967, he was chosen by Academic Press to author the first monograph on Ion Implantation of Semiconductors and by 1970 ion implantation first began being used in the commercial production of integrated circuits.
|
|