Sample records for point-wise backscatter absorption

  1. A Compact In Situ Sensor for Measurement of Absorption and Backscattering in Natural Waters, Phase I (United States)

    National Aeronautics and Space Administration — We propose to develop an active sensor for in situ measurement of the inherent optical properties (IOPs) absorption and backscattering at multiple wavelengths....

  2. A Point-Wise Quantification of Asymmetry Using Deformation Fields

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur; Lanche, Stephanie; Darvann, Tron Andre


    of the resulting displacement vectors on the left and right side of the symmetry plane, gives a point-wise measure of asymmetry. The asymmetry measure was applied to the study of Crouzon syndrome using Micro CT scans of genetically modified mice. Crouzon syndrome is characterised by the premature fusion of cranial...... sutures, which gives rise to a highly asymmetric growth. Quantification and localisation of this asymmetry is of high value with respect to surgery planning and treatment evaluation. Using the proposed method, asymmetry was calculated in each point of the surface of Crouzon mice and wild-type mice...... (controls). Asymmetry appeared in similar regions for the two groups but the Crouzon mice were found significantly more asymmetric. The localisation ability of the method was in good agreement with ratings from a clinical expert. Validating the quantification ability is a less trivial task due to the lack...

  3. Laser source for space-flight elastic backscatter, differential absorption, and wind speed Doppler lidar (United States)

    McKay, Jack A.; Wilkerson, Thomas D.


    Active atmospheric sounding with lidar in principle offers great advantages over passive sounding, including higher spatial resolution and better species selectivity. These improved capabilities have been unavailable in practice due to the great spacecraft burdens of conventional lasers. The long range and high ground speed of spaceflight operation lead to high laser output power requirements. The low efficiency of most lasers leads in turn to exorbitant electrical power and heat removal requirements. Space qualification of Nd:YAG will provide a high efficiency laser suitable for elastic backscatter measurements, but his laser will not be capable of DIAL operation, nor is it practical for an eye-safe wind speed Doppler lidar. Alexandrite is a laser source that is being proven in certain demanding lidar applications, such as resonant backscatter from mesospheric metals. This laser has the great practical advantage of tunability, permitting its use for differential absorption lidar. Laser diode pumping of alexandrite has been demonstrated, using the recently developed short wavelength, high power laser diodes. Laser diode injection seeding of a ring laser yields tunability and extremely narrow linewidth, under 20 MHz. Spaceflight applications of alexandrite are considered, including two- wavelength measurements of aerosols, differential absorption measurements of atmospheric molecules, and Doppler measurement of tropospheric and stratospheric wind speeds. The lidar support requirements are compared to the capabilities of relatively small spacecraft for low cost missions.

  4. Estimating Snow Water Equivalent with Backscattering at X and Ku Band Based on Absorption Loss

    Directory of Open Access Journals (Sweden)

    Yurong Cui


    Full Text Available Snow water equivalent (SWE is a key parameter in the Earth’s energy budget and water cycle. It has been demonstrated that SWE can be retrieved using active microwave remote sensing from space. This necessitates the development of forward models that are capable of simulating the interactions of microwaves and the snow medium. Several proposed models have described snow as a collection of sphere- or ellipsoid-shaped ice particles embedded in air, while the microstructure of snow is, in reality, more complex. Natural snow usually forms a sintered structure following mechanical and thermal metamorphism processes. In this research, the bi-continuous vector radiative transfer (bi-continuous-VRT model, which firstly constructs snow microstructure more similar to real snow and then simulates the snow backscattering signal, is used as the forward model for SWE estimation. Based on this forward model, a parameterization scheme of snow volume backscattering is proposed. A relationship between snow optical thickness and single scattering albedo at X and Ku bands is established by analyzing the database generated from the bi-continuous-VRT model. A cost function with constraints is used to solve effective albedo and optical thickness, while the absorption part of optical thickness is obtained from these two parameters. SWE is estimated after a correction for physical temperature. The estimated SWE is correlated with the measured SWE with an acceptable accuracy. Validation against two-year measurements, using the SnowScat instrument from the Nordic Snow Radar Experiment (NoSREx, shows that the estimated SWE using the presented algorithm has a root mean square error (RMSE of 16.59 mm for the winter of 2009–2010 and 19.70 mm for the winter of 2010–2011.

  5. Converting point-wise nuclear cross sections to pole representation using regularized vector fitting (United States)

    Peng, Xingjie; Ducru, Pablo; Liu, Shichang; Forget, Benoit; Liang, Jingang; Smith, Kord


    Direct Doppler broadening of nuclear cross sections in Monte Carlo codes has been widely sought for coupled reactor simulations. One recent approach proposed analytical broadening using a pole representation of the commonly used resonance models and the introduction of a local windowing scheme to improve performance (Hwang, 1987; Forget et al., 2014; Josey et al., 2015, 2016). This pole representation has been achieved in the past by converting resonance parameters in the evaluation nuclear data library into poles and residues. However, cross sections of some isotopes are only provided as point-wise data in ENDF/B-VII.1 library. To convert these isotopes to pole representation, a recent approach has been proposed using the relaxed vector fitting (RVF) algorithm (Gustavsen and Semlyen, 1999; Gustavsen, 2006; Liu et al., 2018). This approach however needs to specify ahead of time the number of poles. This article addresses this issue by adding a poles and residues filtering step to the RVF procedure. This regularized VF (ReV-Fit) algorithm is shown to efficiently converge the poles close to the physical ones, eliminating most of the superfluous poles, and thus enabling the conversion of point-wise nuclear cross sections.

  6. Measuring global oil trade dependencies: An application of the point-wise mutual information method

    International Nuclear Information System (INIS)

    Kharrazi, Ali; Fath, Brian D.


    Oil trade is one of the most vital networks in the global economy. In this paper, we analyze the 1998–2012 oil trade networks using the point-wise mutual information (PMI) method and determine the pairwise trade preferences and dependencies. Using examples of the USA's trade partners, this research demonstrates the usefulness of the PMI method as an additional methodological tool to evaluate the outcomes from countries' decisions to engage in preferred trading partners. A positive PMI value indicates trade preference where trade is larger than would be expected. For example, in 2012 the USA imported 2,548.7 kbpd despite an expected 358.5 kbpd of oil from Canada. Conversely, a negative PMI value indicates trade dis-preference where the amount of trade is smaller than what would be expected. For example, the 15-year average of annual PMI between Saudi Arabia and the U.S.A. is −0.130 and between Russia and the USA −1.596. We reflect the three primary reasons of discrepancies between actual and neutral model trade can be related to position, price, and politics. The PMI can quantify the political success or failure of trade preferences and can more accurately account temporal variation of interdependencies. - Highlights: • We analyzed global oil trade networks using the point-wise mutual information method. • We identified position, price, & politics as drivers of oil trade preference. • The PMI method is useful in research on complex trade networks and dependency theory. • A time-series analysis of PMI can track dependencies & evaluate policy decisions.

  7. Absorption and backscatter of internal conversion electrons in the measurements of surface contamination of 137Cs

    International Nuclear Information System (INIS)

    Yunoki, A.; Kawada, Y.; Yamada, T.; Unno, Y.; Sato, Y.; Hino, Y.


    We measured 4π and 2π counting efficiencies for internal conversion electrons (ICEs), gross β-particles and also β-rays alone with various source conditions regarding absorber and backing foil thickness using e-X coincidence technique. Dominant differences regarding the penetration, attenuation and backscattering properties among ICEs and β-rays were revealed. Although the abundance of internal conversion electrons of 137 Cs- 137 Ba is only 9.35%, 60% of gross counts may be attributed to ICEs in worse source conditions. This information will be useful for radionuclide metrology and for surface contamination monitoring. - Highlights: • Counting efficiencies for internal conversion electrons from 137 Cs were measured, and compared with those for β-rays. • Electron-X coincidence technique was employed. • A thin NaI(Tl) scintillation detector was used for X-ray detection. • Backscattering fractions of electrons and beta particles were studied by similar experiments

  8. Determination of Spatial Distribution of Air Pollution by Dye Laser Measurement of Differential Absorption of Elastic Backscatter (United States)

    Ahmed, S. A.; Gergely, J. S.


    This paper presents the results of an analytical study of a lidar system which uses tunable organic dye lasers to accurately determine spatial distribution of molecular air pollutants. Also described will be experimental work to date on simultaneous multiwavelength output dye laser sources for this system. Basically the scheme determines the concentration of air pollutants by measuring the differential absorption of an (at least) two wavelength lidar signal elastically backscattered by the atmosphere. Only relative measurements of the backscattered intensity at each of the two wavelengths, one on and one off the resonance absorption of the pollutant in question, are required. The various parameters of the scheme are examined and the component elements required for a system of this type discussed, with emphasis on the dye laser source. Potential advantages of simultaneous multiwavelength outputs are described. The use of correlation spectroscopy in this context is examined. Comparisons are also made for the use of infrared probing wavelengths and sources instead of dye lasers. Estimates of the sensitivity and accuracy of a practical dye laser system of this type, made for specific pollutants, snow it to have inherent advantages over other schemes for determining pollutant spatial distribution.

  9. Resampling-based multiple comparison procedure with application to point-wise testing with functional data. (United States)

    Vsevolozhskaya, Olga A; Greenwood, Mark C; Powell, Scott L; Zaykin, Dmitri V


    In this paper we describe a coherent multiple testing procedure for correlated test statistics such as are encountered in functional linear models. The procedure makes use of two different p -value combination methods: the Fisher combination method and the Šidák correction-based method. P -values for Fisher's and Šidák's test statistics are estimated through resampling to cope with the correlated tests. Building upon these two existing combination methods, we propose the smallest p -value as a new test statistic for each hypothesis. The closure principle is incorporated along with the new test statistic to obtain the overall p -value and appropriately adjust the individual p -values. Furthermore, a shortcut version for the proposed procedure is detailed, so that individual adjustments can be obtained even for a large number of tests. The motivation for developing the procedure comes from a problem of point-wise inference with smooth functional data where tests at neighboring points are related. A simulation study verifies that the methodology performs well in this setting. We illustrate the proposed method with data from a study on the aerial detection of the spectral effect of below ground carbon dioxide leakage on vegetation stress via spectral responses.

  10. Backscattering and absorption coefficients for electrons: Solutions of invariant embedding transport equations using a method of convergence

    International Nuclear Information System (INIS)

    Figueroa, C.; Brizuela, H.; Heluani, S. P.


    The backscattering coefficient is a magnitude whose measurement is fundamental for the characterization of materials with techniques that make use of particle beams and particularly when performing microanalysis. In this work, we report the results of an analytic method to calculate the backscattering and absorption coefficients of electrons in similar conditions to those of electron probe microanalysis. Starting on a five level states ladder model in 3D, we deduced a set of integro-differential coupled equations of the coefficients with a method know as invariant embedding. By means of a procedure proposed by authors, called method of convergence, two types of approximate solutions for the set of equations, namely complete and simple solutions, can be obtained. Although the simple solutions were initially proposed as auxiliary forms to solve higher rank equations, they turned out to be also useful for the estimation of the aforementioned coefficients. In previous reports, we have presented results obtained with the complete solutions. In this paper, we present results obtained with the simple solutions of the coefficients, which exhibit a good degree of fit with the experimental data. Both the model and the calculation method presented here can be generalized to other techniques that make use of different sorts of particle beams

  11. Broad frequency band full field measurements for advanced applications: Point-wise comparisons between optical technologies (United States)

    Zanarini, Alessandro


    The progress of optical systems gives nowadays at disposal on lightweight structures complex dynamic measurements and modal tests, each with its own advantages, drawbacks and preferred usage domains. It is thus more easy than before to obtain highly spatially defined vibration patterns for many applications in vibration engineering, testing and general product development. The potential of three completely different technologies is here benchmarked on a common test rig and advanced applications. SLDV, dynamic ESPI and hi-speed DIC are here first deployed in a complex and unique test on the estimation of FRFs with high spatial accuracy from a thin vibrating plate. The latter exhibits a broad band dynamics and high modal density in the common frequency domain where the techniques can find an operative intersection. A peculiar point-wise comparison is here addressed by means of discrete geometry transforms to put all the three technologies on trial at each physical point of the surface. Full field measurement technologies cannot estimate only displacement fields on a refined grid, but can exploit the spatial consistency of the results through neighbouring locations by means of numerical differentiation operators in the spatial domain to obtain rotational degrees of freedom and superficial dynamic strain distributions, with enhanced quality, compared to other technologies in literature. Approaching the task with the aid of superior quality receptance maps from the three different full field gears, this work calculates and compares rotational and dynamic strain FRFs. Dynamic stress FRFs can be modelled directly from the latter, by means of a constitutive model, avoiding the costly and time-consuming steps of building and tuning a numerical dynamic model of a flexible component or a structure in real life conditions. Once dynamic stress FRFs are obtained, spectral fatigue approaches can try to predict the life of a component in many excitation conditions. Different

  12. Detection of progression of glaucomatous visual field damage using the point-wise method with the binomial test. (United States)

    Karakawa, Ayako; Murata, Hiroshi; Hirasawa, Hiroyo; Mayama, Chihiro; Asaoka, Ryo


    To compare the performance of newly proposed point-wise linear regression (PLR) with the binomial test (binomial PLR) against mean deviation (MD) trend analysis and permutation analyses of PLR (PoPLR), in detecting global visual field (VF) progression in glaucoma. 15 VFs (Humphrey Field Analyzer, SITA standard, 24-2) were collected from 96 eyes of 59 open angle glaucoma patients (6.0 ± 1.5 [mean ± standard deviation] years). Using the total deviation of each point on the 2(nd) to 16(th) VFs (VF2-16), linear regression analysis was carried out. The numbers of VF test points with a significant trend at various probability levels (pbinomial test (one-side). A VF series was defined as "significant" if the median p-value from the binomial test was binomial PLR method (0.14 to 0.86) was significantly higher than MD trend analysis (0.04 to 0.89) and PoPLR (0.09 to 0.93). The PIS of the proposed method (0.0 to 0.17) was significantly lower than the MD approach (0.0 to 0.67) and PoPLR (0.07 to 0.33). The PBNS of the three approaches were not significantly different. The binomial BLR method gives more consistent results than MD trend analysis and PoPLR, hence it will be helpful as a tool to 'flag' possible VF deterioration.

  13. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters (United States)

    Lee, Zhong-Ping; Carder, Kendall L.


    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  14. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    Directory of Open Access Journals (Sweden)

    Diaz Adrian


    Full Text Available Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS. The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms and are achieved at sufficient range (up to 40 m, ~ 130 feet with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  15. Compton backscattering axial spectrometer

    International Nuclear Information System (INIS)

    Rad'ko, V.E.; Mokrushin, A.D.; Razumovskaya, I.V.


    Compton gamma backscattering axial spectrometer of new design with the 200 time larger aperture as compared with the known spectrometers at the equal angular resolution (at E=159 keV) is described. Collimator unit, radiation source and gamma detector are located in the central part of the spectrometer. The investigated specimen (of cylindrical form) and the so called ''black body'' used for absorption of photons, passed through the specimen are placed in the peripheric part. Both these parts have an imaginary symmetry axis that is why the spectrometer is called axial. 57 Co is used as the gamma source. The 122 keV spectral line which corresponds to the 83 keV backscattered photon serves as working line. Germanium disk detector of 10 mm diameter and 4 mm height has energy resolution not worse than 900 eV. The analysis of results of test measurements of compton water profile and their comparison with data obtained earlier show that only finity of detector resolution can essentially affect the form of Compton profile. It is concluded that the suggested variant of the spectrometer would be useful for determination of Compton profiles of chemical compounds of heavy elements [ru

  16. Rutherford Backscattering Spectrometry

    International Nuclear Information System (INIS)

    Gyulai, J.


    The bases of Rutherford ion backscattering and its combination with channeling effect technique are reviewed. This combined method is recently referred to as Backscattering Spectrometry. The measurement of chemical compositions, the detection of crystal defects etc are dealt with. Comparison with other surface analysis methods is also given. The review was delivered as a lecture during the ''International School for Surface Physics'' (Varna, Bulgaria, Sep 18 - Oct 20, 1980). (author)

  17. Spatially coded backscatter radiography

    International Nuclear Information System (INIS)

    Thangavelu, S.; Hussein, E.M.A.


    Conventional radiography requires access to two opposite sides of an object, which makes it unsuitable for the inspection of extended and/or thick structures (airframes, bridges, floors etc.). Backscatter imaging can overcome this problem, but the indications obtained are difficult to interpret. This paper applies the coded aperture technique to gamma-ray backscatter-radiography in order to enhance the detectability of flaws. This spatial coding method involves the positioning of a mask with closed and open holes to selectively permit or block the passage of radiation. The obtained coded-aperture indications are then mathematically decoded to detect the presence of anomalies. Indications obtained from Monte Carlo calculations were utilized in this work to simulate radiation scattering measurements. These simulated measurements were used to investigate the applicability of this technique to the detection of flaws by backscatter radiography

  18. Validation of neutron data libraries by backscattered spectra of Pu-Be Neutrons

    CERN Document Server

    El-Agib, I


    Elastically backscattered spectra of Pu-Be neutrons have been measured for SiO sub 2 , water, graphite, paraffin oil and Al slabs using a proton recoil spectrometer. The results were compared with the calculated spectra obtained by the three-dimensional Monte-Carlo transport code MCNP-4B and point-wise cross sections from the ENDF/B-V, ENDF/B-VI, JENDL-3.1 and BROND-2 data libraries. The good agreement between the measured and calculated results indicates that this procedure can be used for validation of different data libraries. This simple method renders possible the detection of oxygen, carbon and hydrogen in bulk samples. (author)

  19. Bulk media assay using backscattered neutron spectrometry

    International Nuclear Information System (INIS)

    Csikai, J.


    This paper summarized a systematic study of bulk media assay using backscattered neutron spectrometry. The source-sample-detector geometry used for the measurements of leakage and elastically backscattered (EBS) spectra of neutrons is shown. Neutrons up to about 14 MeV were produced via 2 H (d,n) and 9 Be (d,n) reactions using different deuteron beam energies between 5 and 10 MeV at the MGC-20E cyclotron of ATOMKI (Debrecen). Neutron yields of the Pu-Be and 252 Cf sources were 5.25 x 10 6 n/s and 1.8 x 10 6 n/s, respectively. Flux density distributions of thermal and primary 14 MeV neutrons were measured for graphite, water and coal samples in various moderator (M)-sample (S)-reflector (R) geometries. Relative fractions and integrated yields of 252 Cf, Pu-Be and 14 MeV neutrons above the (n,n'γ) reaction thresholds for 12 C, 16 O and 28 Si isotopes vs sample thickness have also been determined. It was found that the integrated reaction rate vs sample thickness decreasing exponentially with different attenuation coefficients depending on the neutron spectrum and the composition of the sample. The spectra of neutrons from sources passing through slabs of water, graphite, sand, Al, Fe and Pb up to 20 cm in thickness have been measured by a PHRS system in the 1.2 to 1.5 MeV range. The leakage neutron spectra from a Pu-Be source placed in the center of 30 cm diameter sphere filled with water, paraffin oil, SiO 2 , zeolite and river sand were also measured. The measured spectra have been compared with the calculated results obtained by the three dimensional Monte-Carlo code MCNP-4A and point-wise cross sections from the ENDF/B-4, ENDF/B-6, ENDF/E-1, BROND-2 and JENDL-3.1 data files. New results were obtained for validation of different data libraries from a comparison on the measured and the calculated spectra. Some typical results for water, Al, sand and Fe are shown. A combination of the backscattered neutron spectrometry with the surface gauge used both for the

  20. Photoelectron backscattering from silicon anodes of hybrid photodetector tubes

    CERN Document Server

    D'Ambrosio, C


    The impact of photoelectron backscattering on spectral distributions measured with hybrid photodetector tubes has been calculated. The calculations are based on the backscattering coefficient mu , the average number of photoelectrons N/sub phel/ emitted from the photocathode, and on the distribution of the fractional photoelectron energy q absorbed in silicon during the backscattering process. We obtained the following results: the average number of absorbed (measured) photoelectrons N/sub meas/ in the silicon anode amounts to ~88% of the incident N/sub phel/. Photoelectron- and gamma-absorption peaks are broadened by a factor 1.043 due to backscattering. As an example, for photomultiplier tubes, this broadening can amount to an average factor of 1.18 due to statistic and gain fluctuations on the dynode chain. (15 refs).

  1. Backscatter imagery in Jobos Bay (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 1x1 meter resolution backscatter mosaic of Jobos Bay, Puerto Rico (in NAD83 UTM 19 North). The backscatter values are in relative 8-bit (0 –...

  2. Characterizing the temporal variability of L-band backscatter using dense UAVSAR time-series in preparation for the NISAR mission (United States)

    Lavalle, M.; Lee, A.; Shiroma, G. X. H.; Rosen, P. A.


    The NASA-ISRO SAR (NISAR) mission will deliver unprecedented global maps of L-band HH/HV backscatter every 12 days with resolution ranging from a few to tens of meters in support of ecosystem, solid Earth and cryosphere science and applications. Understanding and modeling the temporal variability of L-band backscatter over temporal scales of years, months and days is critical for developing retrieval algorithms that can robustly extract the biophysical variables of interest (e.g., forest biomass, soil moisture, etc.) from NISAR time series. In this talk, we will focus on the 5-year time series of 60 JPL/UAVSAR polarimetric images collected near the Sacramento Delta to characterize the inter-annual, seasonal and short-scale variability of the L-band polarimetric backscatter for a broad range of land cover types. Our preliminary analysis reveals that backscatter from man-made structures is very stable over time, whereas backscatter from bare soil and herbaceous vegetation fluctuates over time with standard deviation of 2.3 dB. Land-cover classes with larger biomass such as trees and tall vegetation show about 1.5 dB standard deviation in temporal backscatter variability. Closer examination of high-spatial resolution UAVSAR imagery reveal also that vegetation structure, speckle noise and horizontal forest heterogeneity in the Sacramento Delta area can significantly affect the point-wise backscatter value. In our talk, we will illustrate the long UAVSAR time series, describe our data analysis strategy, show the results of polarimetric variability for different land cover classes and number of looks, and discuss the implications for the development of NISAR L2/L3 retrieval algorithms of ecosystem science.

  3. Multibeam sonar backscatter data processing (United States)

    Schimel, Alexandre C. G.; Beaudoin, Jonathan; Parnum, Iain M.; Le Bas, Tim; Schmidt, Val; Keith, Gordon; Ierodiaconou, Daniel


    Multibeam sonar systems now routinely record seafloor backscatter data, which are processed into backscatter mosaics and angular responses, both of which can assist in identifying seafloor types and morphology. Those data products are obtained from the multibeam sonar raw data files through a sequence of data processing stages that follows a basic plan, but the implementation of which varies greatly between sonar systems and software. In this article, we provide a comprehensive review of this backscatter data processing chain, with a focus on the variability in the possible implementation of each processing stage. Our objective for undertaking this task is twofold: (1) to provide an overview of backscatter data processing for the consideration of the general user and (2) to provide suggestions to multibeam sonar manufacturers, software providers and the operators of these systems and software for eventually reducing the lack of control, uncertainty and variability associated with current data processing implementations and the resulting backscatter data products. One such suggestion is the adoption of a nomenclature for increasingly refined levels of processing, akin to the nomenclature adopted for satellite remote-sensing data deliverables.


    Directory of Open Access Journals (Sweden)

    G. Campbell


    Full Text Available The objective of this work was to examine whether the standard particulate backscattering IOP (Inherent Optical Properties measurement method could be simplified. IOP measurements are essential for parameterising several forms of algorithms used to estimate water quality parameters from airborne and satellite images. Field measurements of the backscattering IOPs are more difficult to make than absorption measurements as correction of the raw Hydroscat-6 backscattering sensor observations is required to allow for the systematic errors associated with the water and water quality parameter absorption. The standard approach involves making simultaneous measurement of the absorption and attenuation of the water with an absorption and attenuation meter (ac-9 or making assumptions about the particulate backscattering probability. Recently, a number of papers have been published that use an alternative method to retrieve the particulate backscattering spectrum by using laboratory measured absorption values and in situ spectroradiometric observations. The alternative method inverts a model of reflectance iteratively using non-linear least squares fitting to solve for the particulate backscattering at 532 nm (bbp0(532 and the particulate backscattering spectral slope (γ. In this paper, eleven observations made at Burdekin Falls Dam, Australia are used to compare the alternative reflectance method to the conventional corrected Hydroscat-6 observations. Assessment of the alternative reflectance method showed that the result of the inversions were highly dependent on the starting conditions. To overcome this limitation, Particle Swarm Optimisation, a stochastic search technique which includes a random element in the search approach, was used. It was found that when compared to the conventionally corrected Hydroscat-6 observations, the alternative reflectance method underestimated bbp0(532 by approximately 50% and overestimated γ by approximately 40

  5. Analytical purpose electron backscattering system

    International Nuclear Information System (INIS)

    Desdin, L.; Padron, I.; Laria, J.


    In this work an analytical purposes electron backscattering system improved at the Center of Applied Studies for Nuclear Development is described. This system can be applied for fast, exact and nondestructive testing of binary and AL/Cu, AL/Ni in alloys and for other applications

  6. Nodule bottom backscattering study using multibeam echosounder

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Raju, Y.S.N.; Nair, R.R.

    A study is carried out to observe the angular dependence of backscattering strength at nodule area where grab sample and photographic data is available. Theoretical study along with the experimentally observed data shows that the backscattering...

  7. Backscatter measurements for NIF ignition targets (invited). (United States)

    Moody, J D; Datte, P; Krauter, K; Bond, E; Michel, P A; Glenzer, S H; Divol, L; Niemann, C; Suter, L; Meezan, N; MacGowan, B J; Hibbard, R; London, R; Kilkenny, J; Wallace, R; Kline, J L; Knittel, K; Frieders, G; Golick, B; Ross, G; Widmann, K; Jackson, J; Vernon, S; Clancy, T


    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ∼15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  8. Backscattering technique to surface inspection

    International Nuclear Information System (INIS)

    Anjos, M.J. dos; Lopes, R.T.


    A new surface inspection system, starting of the backscattering of the gamma radiation is described. A cesium 137 source of 7,4x10 10 Bq (2Ci) and one cintillation detector are used. One calibration curve of the system was obtained. This technique can be very useful when the acess to one of the side of the object in inspection is limited. The scattering angle choosed was 115 0 . The object used was composed of aluminium, brass and stainless steel. The localization of defects is simple and ummediate. (V.R.B.)

  9. Fiber taper characterization by optical backscattering reflectometry. (United States)

    Lai, Yu-Hung; Yang, Ki Youl; Suh, Myoung-Gyun; Vahala, Kerry J


    Fiber tapers provide a way to rapidly measure the spectra of many types of optical microcavities. Proper fabrication of the taper ensures that its width varies sufficiently slowly (adiabatically) along the length of the taper so as to maintain single spatial mode propagation. This is usually accomplished by monitoring the spectral transmission through the taper. In addition to this characterization method it is also helpful to know the taper width versus length. By developing a model of optical backscattering within the fiber taper, it is possible to use backscatter measurements to characterize the taper width versus length. The model uses the concept of a local taper numerical aperture to accurately account for varying backscatter collection along the length of the taper. In addition to taper profile information, the backscatter reflectometry method delineates locations along the taper where fluctuations in fiber core refractive index, cladding refractive index, and taper surface roughness each provide the dominant source of backscattering. Rayleigh backscattering coefficients are also extracted by fitting the data with the model and are consistent with the fiber manufacturer's datasheet. The optical backscattering reflectometer is also used to observe defects resulting from microcracks and surface contamination. All of this information can be obtained before the taper is removed from its fabrication apparatus. The backscattering method should also be prove useful for characterization of nanofibers.

  10. Laboratory experiments on backscattering from regolith samples (United States)

    Kaasalainen, Sanna; Piironen, Jukka; Muinonen, Karri; Karttunen, Hannu; Peltoniemi, Jouni


    The investigation of the backscattering peak has applications in the surface texture characterization of asteroids and planetary surfaces. Laboratory experiments are important because they give an opportunity for systematic variation and comparison of samples. A backscattering experiment from regolith samples, which uses a laser light source and a beam splitter to reach the smallest phase angles, is presented. Measurements at zero and small phase angles for Sahara sand and meteorite rocks are made, and the preliminary results are presented in comparison with the phase curve observed for asteroid 69 Hesperia. The results are applicable to the further interpretation of the coherent backscattering opposition effect.

  11. Stimulated Raman backscattering at high laser intensities

    Energy Technology Data Exchange (ETDEWEB)

    Skoric, M.M. [Vinca Inst. of Nuclear Sciences, Belgrade (Yugoslavia); Tajima, Toshiki; Sasaki, Akira; Maluckov, A.; Jovanovic, M.


    Signatures of Stimulated Raman backscattering of a short-pulse high-intensity laser interacting with an underdense plasma are discussed. We introduce a nonlinear three-wave interaction model that accounts for laser pump depletion and relativistic detuning. A mechanism is revealed based on a generic route to chaos, that predicts a progressive increase of the backscatter complexity with a growing laser intensity. Importance of kinetic effects is outlined and demonstrated in fluid-hybrid and particle simulations. As an application, we show that spectral anomalies of the backscatter, predicted by the above model, are consistent with recent sub-picosecond, high-intensity laser gas-target measurements at Livermore and elsewhere. Finally, a recently proposed scheme for generation of ultra-short, low-prepulse laser pulses by Raman backscattering in a thin foil target, is shown. (author)

  12. SMAPVEX08 PALS Backscatter Data V001 (United States)

    National Aeronautics and Space Administration — This data set contains backscatter data obtained by the Passive Active L-band System (PALS) microwave aircraft radar instrument as part of the Soil Moisture Active...

  13. Retrieving Marine Inherent Optical Properties from Satellites Using Temperature and Salinity-dependent Backscattering by Seawater (United States)

    Werdell, Paul J.; Franz, Bryan Alden; Lefler, Jason Travis; Robinson, Wayne D.; Boss, Emmanuel


    Time-series of marine inherent optical properties (IOPs) from ocean color satellite instruments provide valuable data records for studying long-term time changes in ocean ecosystems. Semi-analytical algorithms (SAAs) provide a common method for estimating IOPs from radiometric measurements of the marine light field. Most SAAs assign constant spectral values for seawater absorption and backscattering, assume spectral shape functions of the remaining constituent absorption and scattering components (e.g., phytoplankton, non-algal particles, and colored dissolved organic matter), and retrieve the magnitudes of each remaining constituent required to match the spectral distribution of measured radiances. Here, we explore the use of temperature- and salinity-dependent values for seawater backscattering in lieu of the constant spectrum currently employed by most SAAs. Our results suggest that use of temperature- and salinity-dependent seawater spectra elevate the SAA-derived particle backscattering, reduce the non-algal particles plus colored dissolved organic matter absorption, and leave the derived absorption by phytoplankton unchanged.

  14. Improved correction methods for field measurements of particulate light backscattering in turbid waters. (United States)

    Doxaran, David; Leymarie, Edouard; Nechad, Bouchra; Dogliotti, Ana; Ruddick, Kevin; Gernez, Pierre; Knaeps, Els


    Monte Carlo simulations are used to compute the uncertainty associated to light backscattering measurements in turbid waters using the ECO-BB (WET Labs) and Hydroscat (HOBI Labs) scattering sensors. ECO-BB measurements provide an accurate estimate of the particulate volume scattering coefficient after correction for absorption along the short instrument pathlength. For Hydroscat measurements, because of a longer photon pathlength, both absorption and scattering effects must be corrected for. As the standard (sigma) correction potentially leads to large errors, an improved correction method is developed then validated using field inherent and apparent optical measurements carried out in turbid estuarine waters. Conclusions are also drawn to guide development of future short pathlength backscattering sensors for turbid waters.

  15. Bathymetry and acoustic backscatter: Estero Bay, California (United States)

    Hartwell, Stephen R.; Finlayson, David P.; Dartnell, Peter; Johnson, Samuel Y.


    Between July 30 and August 9, 2012, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from Estero Bay, San Luis Obispo, California, under PCMSC Field Activity ID S-05-12-SC. The survey was done using the R/V Parke Snavely outfitted with a multibeam sonar for swath mapping and highly accurate position and orientation equipment for georeferencing. This report provides these data in a number of different formats, as well as a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

  16. Card controlled beta backscatter thickness measuring instrument

    International Nuclear Information System (INIS)

    Schlesinger, J.


    An improved beta backscatter instrument for the nondestructive measurement of the thickness of thin coatings on a substrate is described. Included therein is the utilization of a bank of memory stored data representative of isotope, substrate, coating material and thickness range characteristics in association with a control card having predetermined indicia thereon selectively representative of a particular isotope, substrate material, coating material and thickness range for conditioning electronic circuit means by memory stored data selected in accord with the predetermined indicia on a control card for converting backscattered beta particle counts into indicia of coating thickness

  17. Backscattering of light ions from metal surfaces

    International Nuclear Information System (INIS)

    Verbeek, H.


    When a metal target is bombarded with light ions some are implanted and some are reflected from the surface or backscattered from deeper layers. This results in an energy distribution of the backscattered particles which reaches from zero to almost the primary energy. The number of the backscattered particles and their energy, angular, and charge distributions depends largely on the energy and the ion target combination. For high energies (i.e., greater than50 keV for protons) particles are backscattered in a single collision governed by the Rutherford cross section. Protons and He-ions with energies of 100 keV to several MeV are widely used for thin film analysis. For lower energies multiple collisions and the screening of the Coulomb potential have to be taken into account, which makes the theoretical treatment more difficult. This energy region is, however, of special interest in the field of nuclear fusion research. Some recent results for energies below 20 keV are discussed in some detail. (auth)

  18. Simulation of ultrasound backscatter images from fish

    DEFF Research Database (Denmark)

    Pham, An Hoai; Stage, Bjarne; Hemmsen, Martin Christian


    The objective of this work is to investigate ultrasound (US) backscatter in the MHz range from fis to develop a realistic and reliable simulation model. The long term objective of the work is to develop the needed signal processing for fis species differentiation using US. In in-vitro experiments...... images reproduce most of the important characteristics of the measured US image....

  19. Backscatter nephelometer to calibrate scanning lidar (United States)

    Cyle E. Wold; Vladmir A. Kovalev; Wei Min Hao


    The general concept of an open-path backscatter nephelometer, its design, principles of calibration and the operational use are discussed. The research-grade instrument, which operates at the wavelength 355 nm, will be co-located with a scanning-lidar at measurement sites near wildfires, and used for the lidar calibration. Such a near-end calibration has significant...

  20. Preliminary backscatter results from the hydrosweep multibeam system

    Digital Repository Service at National Institute of Oceanography (India)

    Hagen, R.A.; Chakraborty, B.; Schenke, H.W.

    of Oceanography to convert the measured electrical energy into acoustic backscatter energy. This conversion includes corrections for the position, slope, and area of the scattering surface. In this paper we present backscatter data from several areas surveyed...

  1. San Francisco Bay Multi-beam Backscatter Imagery: Area A (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery data were collected over shallow subtidal areas in the San Francisco Bay estuary system. Bathymetric and acoustic backscatter data were collected...

  2. An algorithm to determine backscattering ratio and single scattering albedo

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

    and backscattering coefficients and the remote sensing reflectance are used to obtain a relationship for the backscattering ratio, which is defined as the ratio of the total backscattering to the total scattering in terms of the remote sensing reflectance of two...

  3. Contribution of backscattered electrons to the total electron yield ...

    Indian Academy of Sciences (India)

    It is shown experimentally that under energetic electron bombardment the backscattered electrons from solid targets contribute significantly (∼ 80%) to the observed total electron yield, even for targets of high backscattering coefficients. It is further found that for tungsten ( = 74) with a backscattering coefficient of about 0.50 ...

  4. Backscattering and Nonparaxiality Arrest Collapse of Damped Nonlinear Waves (United States)

    Fibich, G.; Ilan, B.; Tsynkov, S.


    The critical nonlinear Schrodinger equation (NLS) models the propagation of intense laser light in Kerr media. This equation is derived from the more comprehensive nonlinear Helmholtz equation (NLH) by employing the paraxial approximation and neglecting the backscattered waves. It is known that if the input power of the laser beam (i.e., L(sub 2) norm of the initial solution) is sufficiently high, then the NLS model predicts that the beam will self-focus to a point (i.e.. collapse) at a finite propagation distance. Mathematically, this behavior corresponds to the formation of a singularity in the solution of the NLS. A key question which has been open for many years is whether the solution to the NLH, i.e., the 'parent' equation, may nonetheless exist and remain regular everywhere, in particular for those initial conditions (input powers) that lead to blowup in the NLS. In the current study, we address this question by introducing linear damping into both models and subsequently comparing the numerical solutions of the damped NLH (boundary-value problem) with the corresponding solutions of the damped NLS (initial-value problem). Linear damping is introduced in much the same way as done when analyzing the classical constant-coefficient Helmholtz equation using the limiting absorption principle. Numerically, we have found that it provides a very efficient tool for controlling the solutions of both the NLH and NHS. In particular, we have been able to identify initial conditions for which the NLS solution does become singular. whereas the NLH solution still remains regular everywhere. We believe that our finding of a larger domain of existence for the NLH than that for the NLS is accounted for by precisely those mechanisms, that have been neglected when deriving the NLS from the NLH, i.e., nonparaxiality and backscattering.

  5. Backscattering and negative polarization of agglomerate particles. (United States)

    Zubko, Evgenij; Shkuratov, Yuriy; Hart, Matthew; Eversole, Jay; Videen, Gorden


    We used the discrete dipole approximation to study the backscattering of agglomerate particles consisting of oblong monomers. We varied the aspect ratio of the monomers from approximately 1 (sphere) to 4, while we kept the total particle volume equivalent to that of an x = 10 sphere for m = 1.59 + i0 and 1.50 + i0 and considered two values of agglomerate packing density: rho = 0.25 and rho = 0.1. We found that these particles do not display a prominent brightness opposition effect but do produce significant negative polarization over a range of near-backscattering angles. Increasing the monomers' aspect ratio can make the negative polarization much more prominent. We have noted also that decreasing m and p can reduce the amplitude of the negative polarization for these particles.

  6. Analytical expressions for the electron backscattering coefficient

    International Nuclear Information System (INIS)

    August, H.J.; Wernisch, J.


    Several analytical expressions for the electron backscattering coefficient for massive homogeneous samples are compared with experimental data, directing special attention to the dependence of this quantity on the electron acceleration energy. It is shown that this dependence generally cannot be neglected. The expression proposed by Hunger and Kuechler turns out to be better than that of Love and Scott, although even the better formula can be slightly improved by a small modification. (author)

  7. Backscatter Correction Algorithm for TBI Treatment Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Nieto, B.; Sanchez-Doblado, F.; Arrans, R.; Terron, J.A. [Dpto. Fisiología Médica y Biofísica, Universidad de Sevilla, Avda. Sánchez Pizjuán, 4. E-41009, Sevilla (Spain); Errazquin, L. [Servicio Oncología Radioterápica, Hospital Univ.V. Macarena. Dr. Fedriani, s/n. E-41009, Sevilla (Spain)


    The accuracy requirements in target dose delivery is, according to ICRU, ±5%. This is so not only in standard radiotherapy but also in total body irradiation (TBI). Physical dosimetry plays an important role in achieving this recommended level. The semi-infinite phantoms, customarily used for dosimetry purposes, give scatter conditions different to those of the finite thickness of the patient. So dose calculated in patient’s points close to beam exit surface may be overestimated. It is then necessary to quantify the backscatter factor in order to decrease the uncertainty in this dose calculation. The backward scatter has been well studied at standard distances. The present work intends to evaluate the backscatter phenomenon under our particular TBI treatment conditions. As a consequence of this study, a semi-empirical expression has been derived to calculate (within 0.3% uncertainty) the backscatter factor. This factor depends lineally on the depth and exponentially on the underlying tissue. Differences found in the qualitative behavior with respect to standard distances are due to scatter in the bunker wall close to the measurement point.

  8. Backscatter and attenuation characterization of ventricular myocardium (United States)

    Gibson, Allyson Ann


    This Dissertation presents quantitative ultrasonic measurements of the myocardium in fetal hearts and adult human hearts with the goal of studying the physics of sound waves incident upon anisotropic and inhomogeneous materials. Ultrasound has been used as a clinical tool to assess heart structure and function for several decades. The clinical usefulness of this noninvasive approach has grown with our understanding of the physical mechanisms underlying the interaction of ultrasonic waves with the myocardium. In this Dissertation, integrated backscatter and attenuation analyses were performed on midgestational fetal hearts to assess potential differences in the left and right ventricular myocardium. The hearts were interrogated using a 50 MHz transducer that enabled finer spatial resolution than could be achieved at more typical clinical frequencies. Ultrasonic data analyses demonstrated different patterns and relative levels of backscatter and attenuation from the myocardium of the left ventricle and the right ventricle. Ultrasonic data of adult human hearts were acquired with a clinical imaging system and quantified by their magnitude and time delay of cyclic variation of myocardial backscatter. The results were analyzing using Bayes Classification and ROC analysis to quantify potential advantages of using a combination of two features of cyclic variation of myocardial backscatter over using only one or the other feature to distinguish between groups of subjects. When the subjects were classified based on hemoglobin A1c, the homeostasis model assessment of insulin resistance, and the ratio of triglyceride to high-density lipoprotein-cholesterol, differences in the magnitude and normalized time delay of cyclic variation of myocardial backscatter were observed. The cyclic variation results also suggested a trend toward a larger area under the ROC curve when information from magnitude and time delay of cyclic variation is combined using Bayes classification than when

  9. Ultrasonic absorption

    International Nuclear Information System (INIS)

    Beyer, R.T.


    The paper reviews studies of ultrasonic absorption in liquid alkali metals. The experimental methods to measure the absorption coefficients are briefly described. Experimental results reported for the liquid metals: sodium, potassium, rubidium and caesium, at medium temperatures, are presented, as well as data for liquid alloys. Absorption losses due to the presence of an external magnetic field, and the effects of viscosity on the absorption in metals, are both discussed. (U.K.)

  10. An Ultrasonic Backscatter Instrument for Cancellous Bone Evaluation in Neonates

    Directory of Open Access Journals (Sweden)

    Chengcheng Liu


    Full Text Available Ultrasonic backscatter technique has shown promise as a noninvasive cancellous bone assessment tool. A novel ultrasonic backscatter bone diagnostic (UBBD instrument and an in vivo application for neonatal bone evaluation are introduced in this study. The UBBD provides several advantages, including noninvasiveness, non-ionizing radiation, portability, and simplicity. In this study, the backscatter signal could be measured within 5 s using the UBBD. Ultrasonic backscatter measurements were performed on 467 neonates (268 males and 199 females at the left calcaneus. The backscatter signal was measured at a central frequency of 3.5 MHz. The delay (T1 and duration (T2 of the backscatter signal of interest (SOI were varied, and the apparent integrated backscatter (AIB, frequency slope of apparent backscatter (FSAB, zero frequency intercept of apparent backscatter (FIAB, and spectral centroid shift (SCS were calculated. The results showed that the SOI selection had a direct influence on cancellous bone evaluation. The AIB and FIAB were positively correlated with the gestational age (|R| up to 0.45, P10 µs. Moderate positive correlations (|R| up to 0.45, P10 µs. The T2 mainly introduced fluctuations in the observed correlation coefficients. The moderate correlations observed with UBBD demonstrate the feasibility of using the backscatter signal to evaluate neonatal bone status. This study also proposes an explicit standard for in vivo SOI selection and neonatal cancellous bone assessment.

  11. Backscattering Moessbauer spectroscopy of Martian dust

    International Nuclear Information System (INIS)

    Bertelsen, P.; Madsen, M. B.; Binau, C. S.; Goetz, W.; Gunnlaugsson, H. P.; Hviid, S. F.; Kinch, K. M.; Klingelhoefer, G.; Leer, K.; Madsen, D. E.; Merrison, J.; Olsen, M.; Squyres, S. W.


    We report on the determination of the mineralogy of the atmospherically suspended Martian dust particles using backscattering 57 Fe Moessbauer spectroscopy on dust accumulated onto the magnets onboard the Mars Exploration Rovers. The spectra can be interpreted in terms of minerals of igneous origin, and shows only limited, if any, amounts of secondary minerals that may have formed in the presence of liquid water. These findings suggest that the dust has formed in a dry environment over long time in the history of the planet.

  12. Understanding the radar backscattering from flooded and nonflooded Amazonian forests: results from canopy backscatter modeling

    International Nuclear Information System (INIS)

    Wang, Y.; Hess, L.L.; Filoso, S.; Melack, J.M.


    To understand the potential of using multiwavelength imaging radars to detect flooding in Amazonian floodplain forests, we simulated the radar backscatter from a floodplain forest with a flooded or nonflooded ground condition at C-, L-, and P-bands. Field measurements of forest structure in the Anavilhanas archipelago of the Negro River, Brazil, were used as inputs to the model. Given the same wavelength or incidence angle, the ratio of backscatter from the flooded forest to that from the nonflooded forest was higher at HH polarization than at VV polarization. Given the same wavelength or polarization, the ratio was larger at small incidence angles than at large incidence angles. Given the same polarization or incidence angle, the ratio was larger at a long wavelength than at a short wavelength. As the surface soil moisture underneath the nonflooded forest increased from 10% to 50% of volumetric moisture, the flooded/nonflooded backscatter ratio decreased; the decreases were small at C- and L-band but large at P-band. When the leaf size was comparable to or larger than the wavelength of C-band, the leaf area index (LAI) had a large effect on the simulated C-band (not L-band or P-band) backscatter from the flooded and nonflooded forests. (author)

  13. Uniqueness for the inverse backscattering problem for angularly controlled potentials

    International Nuclear Information System (INIS)

    Rakesh; Uhlmann, Gunther


    We consider the problem of recovering a smooth, compactly supported potential on R 3 from its backscattering data. We show that if two such potentials have the same backscattering data and the difference of the two potentials has controlled angular derivatives, then the two potentials are identical. In particular, if two potentials differ by a finite linear combination of spherical harmonics with radial coefficients and have the same backscattering data then the two potentials are identical. (paper)

  14. Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar. (United States)

    Foote, Kenneth G


    Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1-6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.

  15. Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band (United States)

    Taher Al-Nuaimi, Mustafa K.; Hong, Wei; He, Yejun


    The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180°  ±  35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50  ×  50 mm2 surface is fabricated and measured.

  16. Absorption studies

    International Nuclear Information System (INIS)

    Ganatra, R.D.


    Absorption studies were once quite popular but hardly anyone does them these days. It is easier to estimate the blood level of the nutrient directly by radioimmunoassay (RIA). However, the information obtained by estimating the blood levels of the nutrients is not the same that can be obtained from the absorption studies. Absorption studies are primarily done to find out whether some of the essential nutrients are absorbed from the gut or not and if they are absorbed, to determine how much is being absorbed. In the advanced countries, these tests were mostly done to detect pernicious anaemia where vitamin B 12 is not absorbed because of the lack of the intrinsic factor in the stomach. In the tropical countries, ''malabsorption syndrome'' is quire common. In this condition, several nutrients like fat, folic acid and vitamin B 12 are not absorbed. It is possible to study absorption of these nutrients by radioisotopic absorption studies

  17. Initial backscatter occurrence statistics from the CUTLASS HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available A statistical study of the occurrence of ground and ionospheric backscatter within the fields-of-view of the CUTLASS HF radars, at an operating frequency of 10 MHz, during the first 20 months of operation has been undertaken. The diurnal variation of the occurrence of backscatter and the range at which such backscatter is observed is found to be highly dependent on seasonal changes of the ionospheric electron density in both the E and F region, determined from ionosonde observations. In general, ionospheric backscatter is observed at far ranges during the local day in winter months and at near ranges during the local night in summer months. The Iceland radar observes more near-range E region backscatter than the Finland radar as a consequence of its more zonal look-direction. The dependence of the occurrence of backscatter on geomagnetic activity and radar operating frequency are also investigated. The occurrence of ground and ionospheric backscatter is discussed in terms of HF propagation modes and ionospheric electron densities as well as geophysical processes. A brief assessment of the possible impact of solar cycle variations on the observations is made and frequency management is discussed. Such a study, with its focus on the `instrumental' aspect of backscatter occurrence, is essential for a full interpretation of HF coherent radar observations.

  18. Strong Localization in Disordered Media: Analysis of the Backscattering Cone

    KAUST Repository

    Delgado, Edgar


    A very interesting effect in light propagation through a disordered system is Anderson localization of light, this phenomenon emerges as the result of multiple scattering of waves by electric inhomogeneities like spatial variations of index of refraction; as the amount of scattering is increased, light propagation is converted from quasi-diffusive to exponentially localized, with photons confined in a limited spatial region characterized by a fundamental quantity known as localization length. Light localization is strongly related to another interference phenomenon emerged from the multiple scattering effect: the coherent backscattering effect. In multiple scattering of waves, in fact, coherence is preserved in the backscattering direction and produces a reinforcement of the field flux originating an observable peak in the backscattered intensity, known as backscattering cone. The study of this peak provide quantitative information about the transport properties of light in the material. In this thesis we report a complete FDTD ab-initio study of light localization and coherent backscattering. In particular, we consider a supercontinuum pulse impinging on a sample composed of randomly positioned scatterers. We study coherent backscattering by averaging over several realizations of the sample properties. We study then the coherent backscattering cone properties as the relative permittivity of the sample is changed, relating the latter with the light localization inside the sample. We demonstrate important relationships between the width of the backscattering cone and the localization length, which shows a linear proportionality in the strong localization regime.

  19. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    Abstract. The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between EB = 50 eV and 5000. eV. The angle of incidence α and take-off angle θ are ...

  20. Energy and angular distributions of backscattered electrons from ...

    Indian Academy of Sciences (India)

    The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between B = 50 eV and 5000 eV. The angle of incidence α and take-off angle are chosen to have ...

  1. Infrared reflectometry of skin: Analysis of backscattered light from different skin layers (United States)

    Pleitez, Miguel A.; Hertzberg, Otto; Bauer, Alexander; Lieblein, Tobias; Glasmacher, Mathias; Tholl, Hans; Mäntele, Werner


    We have recently reported infrared spectroscopy of human skin in vivo using quantum cascade laser excitation and photoacoustic or photothermal detection for non-invasive glucose measurement . Here, we analyze the IR light diffusely reflected from skin layers for spectral contributions of glucose. Excitation of human skin by an external cavity tunable quantum cascade laser in the spectral region from 1000 to 1245 cm- 1, where glucose exhibits a fingerprint absorption, yields reflectance spectra with some contributions from glucose molecules. A simple three-layer model of skin was used to calculate the scattering intensities from the surface and from shallow and deeper layers using the Boltzmann radiation transfer equation. Backscattering of light at wavelengths around 10 μm from the living skin occurs mostly from the Stratum corneum top layers and the shallow layers of the living epidermis. The analysis of the polarization of the backscattered light confirms this calculation. Polarization is essentially unchanged; only a very small fraction (< 3%) is depolarized at 90° with respect to the laser polarization set at 0°. Based on these findings, we propose that the predominant part of the backscattered light is due to specular reflectance and to scattering from layers close to the surface. Diffusely reflected light from deeper layers undergoing one or more scattering processes would appear with significantly altered polarization. We thus conclude that a non-invasive glucose measurement based on backscattering of IR light from skin would have the drawback that only shallow layers containing some glucose at concentrations only weakly related to blood glucose are monitored.

  2. Backscattering at a pulsed neutron source, the MUSICAL instrument

    International Nuclear Information System (INIS)

    Alefeld, B.


    In the first part the principles of the neutron backscattering method are described and some simple considerations about the energy resolution and the intensity are presented. A prototype of a backscattering instrument, the first Juelich instrument, is explained in some detail and a representative measurement is shown which was performed on the backscattering instrument IN10 at the ILL in Grenoble. In the second part a backscattering instrument designed for a pulsed neutron source is proposed. It is shown that a rather simple modification, which consists in the replacement of the Doppler drive of the conventional backscattering instrument by a multi silicon monochromator crystal (MUSICAL) leads to a very effective instrument, benefitting from the peak flux of the pulsed source. ((orig.))


    Directory of Open Access Journals (Sweden)



    Full Text Available The change in backscattering parameters during the appearance of chilling injury in bananas was investigated. Bananas were stored at a chilling temperature for two days and the degrees of the chilling injuries that appeared were measured before, during and after storage using backscattering imaging and visual assessment. Laser lights at 660 nm and 785 nm wavelengths were shot consecutively onto the samples in a dark room and a camera was used to capture the backscattered lights that appeared on the samples. The captured images were analysed and the changes of intensity against pixel count were plotted into graphs. The plotted graph provides useful information of backscattering parameters such as inflection point (IP, slope after inflection point (SA, and full width at half maximum (FWHM and saturation radius (RSAT. Results of statistical analysis indicated that there were significant changes of these backscattering parameters as chilling injury developed.

  4. Backscattering at a pulsed neutron source, the MUSICAL instrument (United States)

    Alefeld, B.


    In the first part the principles of the neutron backscattering method are described and some simple considerations about the energy resolution and the intensity are presented. A prototype of a backscattering instrument, the first Jülich instrument, is explained in some detail and a representative measurement is shown which was performed on the backscattering instrument IN10 at the ILL in Grenoble. In the second part a backscattering instrument designed for a pulsed neutron source is proposed. It is shown that a rather simple modification, which consists in the replacement of the Doppler drive of the conventional backscattering instrument by a multi silicon monochromator cryst al (MUSICAL) leads to a very effective instrument, benefitting from the peak flux of the pulsed source.

  5. Folate absorption

    International Nuclear Information System (INIS)

    Baker, S.J.


    Folate is the generic term given to numerous compounds of pteroic acid with glutamic acid. Knowledge of absorption is limited because of the complexities introduced by the variety of compounds and because of the inadequacy of investigational methods. Two assay methods are in use, namely microbiological and radioactive. Techniques used to study absorption include measurement of urinary excretion, serum concentration, faecal excretion, intestinal perfusion, and haematological response. It is probably necessary to test absorption of both pteroylmonoglutamic acid and one or more polyglutamates, and such tests would be facilitated by availability of synthesized compounds labelled with radioactive tracers at specifically selected sites. (author)

  6. Multi-beam backscatter image data processing techniques employed to EM 1002 system

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, W.A.; Chakraborty, B.

    to compensate outer-beam backscatter strength data in such a way that the effect of angular backscatter strength is removed. In this work we have developed backscatter data processing techniques for EM1002 multi-beam system...

  7. Narrative absorption

    DEFF Research Database (Denmark)

    Narrative Absorption brings together research from the social sciences and Humanities to solve a number of mysteries: Most of us will have had those moments, of being totally absorbed in a book, a movie, or computer game. Typically we do not have any idea about how we ended up in such a state. Nor...... do we fully realize how we might have changed as we return for the fictional worlds we have visited. The feeling of being absorbed is one of the most illusive and transient feelings, but also one that motivates audiences to spend considerable amounts of time in narrative worlds, and one...... that is central to our understanding of the effects of narratives on beliefs and behavior. Key specialists inform the reader of this book about the nature of the peculiar state of consciousness during episodes of absorption, the perception of absorption in history, the role of absorption in meaningful experiences...

  8. Quantitative characterization of abyssal seafloor with transit multibeam backscatter data (United States)

    Pockalny, R. A.; Ferrini, V. L.


    The expanding volume of deep-water multibeam echosounder data provides emerging opportunities for the improved characterization of the abyssal seafloor. Nearly 500 cruises criss-cross the oceans with modern wide-swath multibeam systems, and these cruise tracks have imaged a variety of morphologic, tectonic and magmatic environments. The qualitative analysis of the seafloor backscatter data strongly suggests a local and regional variability that correlates with sediment thickness, sediment type and/or depositional environment. We present our initial attempts to develop a method that quantifies this observed seafloor backscatter variability and to explore the causes and potential implications of this variability. Our approach is rooted in the Angular Range Analysis methodology, which utilizes changes in backscatter amplitude observed as a function of grazing angle, to characterize the seafloor. The primary difference in our approach is that we do not invert for geo-acoustical parameters, but rather explores empirical relationships between geological observations and stacked slope and y-intercept values. In addition, we also include the mean and the variance of detrended backscatter measurements. Our initial results indicate intriguing relationships between backscatter parameters and the CaCO3 content of surface sediments. Seafloor regions reported to have high manganese nodule concentrations also tend to have characteristic trends in backscatter parameters. We will present these regional correlations as well as some preliminary statistical analyses of the backscatter parameters and key environmental factors.

  9. Coherent Backscattering by Particulate Planetary Media of Nonspherical Particles (United States)

    Muinonen, Karri; Penttila, Antti; Wilkman, Olli; Videen, Gorden


    The so-called radiative-transfer coherent-backscattering method (RT-CB) has been put forward as a practical Monte Carlo method to compute multiple scattering in discrete random media mimicking planetary regoliths (K. Muinonen, Waves in Random Media 14, p. 365, 2004). In RT-CB, the interaction between the discrete scatterers takes place in the far-field approximation and the wave propagation faces exponential extinction. There is a significant constraint in the RT-CB method: it has to be assumed that the form of the scattering matrix is that of the spherical particle. We aim to extend the RT-CB method to nonspherical single particles showing significant depolarization characteristics. First, ensemble-averaged single-scattering albedos and phase matrices of nonspherical particles are matched using a phenomenological radiative-transfer model within a microscopic volume element. Second, the phenomenologial single-particle model is incorporated into the Monte Carlo RT-CB method. In the ray tracing, the electromagnetic phases within the microscopic volume elements are omitted as having negligible lengths, whereas the phases are duly accounted for in the paths between two or more microscopic volume elements. We assess the computational feasibility of the extended RT-CB method and show preliminary results for particulate media mimicking planetary regoliths. The present work can be utilized in the interpretation of astronomical observations of asteroids and other planetary objects. In particular, the work sheds light on the depolarization characteristics of planetary regoliths at small phase angles near opposition. The research has been partially funded by the ERC Advanced Grant No 320773 entitled “Scattering and Absorption of Electromagnetic Waves in Particulate Media” (SAEMPL), by the Academy of Finland (contract 257966), NASA Outer Planets Research Program (contract NNX10AP93G), and NASA Lunar Advanced Science and Exploration Research Program (contract NNX11AB25G).

  10. Interference phenomena at backscattering by ice crystals of cirrus clouds. (United States)

    Borovoi, Anatoli; Kustova, Natalia; Konoshonkin, Alexander


    It is shown that light backscattering by hexagonal ice crystals of cirrus clouds is formed within the physical-optics approximation by both diffraction and interference phenomena. Diffraction determines the angular width of the backscattering peak and interference produces the interference rings inside the peak. By use of a simple model for distortion of the pristine hexagonal shape, we show that the shape distortion leads to both oscillations of the scattering (Mueller) matrix within the backscattering peak and to a strong increase of the depolarization, color, and lidar ratios needed for interpretation of lidar signals.

  11. Reson 8101 multibeam backscatter data from Galvez Bank. (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the Mariana archipelago between the U.S. Territory of Guam and Farallon De Pajaros Island in the...

  12. Using Backscattering to Enhance Efficiency in Neutron Detectors

    DEFF Research Database (Denmark)

    Kittelmann, T.; Kanaki, K.; Klinkby, Esben Bryndt


    The principle of using strongly scattering materials to recover efficiency in detectors for neutron instruments, via backscattering of unconverted thermal neutrons, is discussed in general. The feasibility of the method is illustrated through Geant4-based simulations involving thermal neutrons...

  13. Reson 8101 Backscatter imagery of Penguin Bank, Molokai, Hawaii, USA (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery extracted from gridded bathymetry of Penguin Bank, Molokai, Hawaii, USA. These data provide almost complete coverage between 0 and 100 meters....

  14. Optical Backscattering Measured by Airborne Lidar and Underwater Glider

    Directory of Open Access Journals (Sweden)

    James H. Churnside


    Full Text Available The optical backscattering from particles in the ocean is an important quantity that has been measured by remote sensing techniques and in situ instruments. In this paper, we compare estimates of this quantity from airborne lidar with those from an in situ instrument on an underwater glider. Both of these technologies allow much denser sampling of backscatter profiles than traditional ship surveys. We found a moderate correlation (R = 0.28, p < 10−5, with differences that are partially explained by spatial and temporal sampling mismatches, variability in particle composition, and lidar retrieval errors. The data suggest that there are two different regimes with different scattering properties. For backscattering coefficients below about 0.001 m−1, the lidar values were generally greater than the glider values. For larger values, the lidar was generally lower than the glider. Overall, the results are promising and suggest that airborne lidar and gliders provide comparable and complementary information on optical particulate backscattering.

  15. Principles of electron backscattering by solids and thin films

    International Nuclear Information System (INIS)

    Niedrig, H.


    The parameters concerning the electron backscattering from thin films and solids (atomic scattering cross-section, atomic number, single/multiple scattering, film thickness of self-supporting films and of surface films on bulk substrates, scattering angular distribution, angle of incidence, diffraction effects) are described. Their influence on some important contrast mechanisms in scanning electron microscopy (thickness contrast, Z/material contrast, tilting/topography contrast, orientation contrast) is discussed. The main backscattering electron detection systems are briefly described. (orig.) [de

  16. Optical Backscattering Measured by Airborne Lidar and Underwater Glider


    James H. Churnside; Richard D. Marchbanks; Chad Lembke; Jordon Beckler


    The optical backscattering from particles in the ocean is an important quantity that has been measured by remote sensing techniques and in situ instruments. In this paper, we compare estimates of this quantity from airborne lidar with those from an in situ instrument on an underwater glider. Both of these technologies allow much denser sampling of backscatter profiles than traditional ship surveys. We found a moderate correlation (R = 0.28, p < 10−5), with differences that are partially ex...

  17. Estimation of Single-Crystal Elastic Constants of Polycrystalline Materials from Back-Scattered Grain Noise

    International Nuclear Information System (INIS)

    Haldipur, P.; Margetan, F. J.; Thompson, R. B.


    Single-crystal elastic stiffness constants are important input parameters for many calculations in material science. There are well established methods to measure these constants using single-crystal specimens, but such specimens are not always readily available. The ultrasonic properties of metal polycrystals, such as velocity, attenuation, and backscattered grain noise characteristics, depend in part on the single-crystal elastic constants. In this work we consider the estimation of elastic constants from UT measurements and grain-sizing data. We confine ourselves to a class of particularly simple polycrystalline microstructures, found in some jet-engine Nickel alloys, which are single-phase, cubic, equiaxed, and untextured. In past work we described a method to estimate the single-crystal elastic constants from measured ultrasonic velocity and attenuation data accompanied by metallographic analysis of grain size. However, that methodology assumes that all attenuation is due to grain scattering, and thus is not valid if appreciable absorption is present. In this work we describe an alternative approach which uses backscattered grain noise data in place of attenuation data. Efforts to validate the method using a pure copper specimen are discussed, and new results for two jet-engine Nickel alloys are presented

  18. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Directory of Open Access Journals (Sweden)

    M. Proksch


    Full Text Available The Microwave Emission Model of Layered Snowpacks (MEMLS was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like- and cross-polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS is set up in a way that snow input parameters can be derived by objective measurement methods which avoid fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx (Nordic Snow Radar Experiment campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in Matlab and the code is publicly available for download through the following website:

  19. Solar Backscatter UV (SBUV total ozone and profile algorithm

    Directory of Open Access Journals (Sweden)

    P. K. Bhartia


    Full Text Available We describe the algorithm that has been applied to develop a 42 yr record of total ozone and ozone profiles from eight Solar Backscatter UV (SBUV instruments launched on NASA and NOAA satellites since April 1970. The Version 8 (V8 algorithm was released more than a decade ago and has been in use since then at NOAA to produce their operational ozone products. The current algorithm (V8.6 is basically the same as V8, except for updates to instrument calibration, incorporation of new ozone absorption cross-sections, and new ozone and cloud height climatologies. Since the V8 algorithm has been optimized for deriving monthly zonal mean (MZM anomalies for ozone assessment and model comparisons, our emphasis in this paper is primarily on characterizing the sources of errors that are relevant for such studies. When data are analyzed this way the effect of some errors, such as vertical smoothing of short-term variability, and noise due to clouds and aerosols diminish in importance, while the importance of others, such as errors due to vertical smoothing of the quasi-biennial oscillation (QBO and other periodic and aperiodic variations, become more important. With V8.6 zonal mean data we now provide smoothing kernels that can be used to compare anomalies in SBUV profile and partial ozone columns with models. In this paper we show how to use these kernels to compare SBUV data with Microwave Limb Sounder (MLS ozone profiles. These kernels are particularly useful for comparisons in the lower stratosphere where SBUV profiles have poor vertical resolution but partial column ozone values have high accuracy. We also provide our best estimate of the smoothing errors associated with SBUV MZM profiles. Since smoothing errors are the largest source of uncertainty in these profiles, they can be treated as error bars in deriving interannual variability and trends using SBUV data and for comparing with other measurements. In the V8 and V8.6 algorithms we derive total

  20. Polarized gamma-rays with laser-Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S. [Electrotechnical Lab., Ibaraki (Japan)] [and others


    Polarized gamma-rays were generated through laser-Compton backscattering (LCS) of a conventional Nd:YAG laser with electrons circulating in the electron storage ring TERAS at Electrotechnical Laboratory. We measured the energy, the energy spread, and the yield of the gamma-rays to characterize our gamma-ray source. The gamma-ray energy can be varied by changing the energy of the electrons circulating the storage ring. In our case, the energy of electrons in the storage ring were varied its energy from 200 to 750 MeV. Consequently, we observed gamma-ray energies of 1 to 10 MeV with 1064 run laser photons. Furthermore, the gamma-ray energy was extended to 20 MeV by using the 2nd harmonic of the Nd:YAG laser. This shows a good agreement with theoretical calculation. The gamma-ray energy spread was also measured to be 1% FWHM for -1 MeV gamma-rays and to be 4% FWHM for 10 MeV gamma-rays with a narrow collimator that defined the scattering cone. The gamma-ray yield was 47.2 photons/mA/W/s. This value is consistent with a rough estimation of 59.5 photons/mA/W/s derived from theory. Furthermore, we tried to use these gamma-rays for a nuclear fluorescence experiment. If we use a polarized laser beam, we can easily obtain polarized gamma-rays. Elastically scattered photons from {sup 208} Pb were clearly measured with the linearly polarized gamma-rays, and we could assign the parity of J=1 states in the nucleus. We should emphasize that the polarized gamma-ray from LCS is quit useful in this field, because we can use highly, almost completely, polarized gamma-rays. We also use the LCS gamma-rays to measure the photon absorption coefficients. In near future, we will try to generate a circular polarized gamma-ray. We also have a plan to use an FEL, because it can produce intense laser photons in the same geometric configuration as the LCS facility.

  1. Probabilities and statistics for backscatter estimates obtained by a scatterometer (United States)

    Pierson, Willard J., Jr.


    Methods for the recovery of winds near the surface of the ocean from measurements of the normalized radar backscattering cross section must recognize and make use of the statistics (i.e., the sampling variability) of the backscatter measurements. Radar backscatter values from a scatterometer are random variables with expected values given by a model. A model relates backscatter to properties of the waves on the ocean, which are in turn generated by the winds in the atmospheric marine boundary layer. The effective wind speed and direction at a known height for a neutrally stratified atmosphere are the values to be recovered from the model. The probability density function for the backscatter values is a normal probability distribution with the notable feature that the variance is a known function of the expected value. The sources of signal variability, the effects of this variability on the wind speed estimation, and criteria for the acceptance or rejection of models are discussed. A modified maximum likelihood method for estimating wind vectors is described. Ways to make corrections for the kinds of errors found for the Seasat SASS model function are described, and applications to a new scatterometer are given.

  2. Acoustic backscatter at a Red Sea whale shark aggregation site

    KAUST Repository

    Hozumi, Aya


    An aggregation of sexually immature whale sharks occurs at a coastal submerged reef near the Saudi Arabian Red Sea coast each spring. We tested the hypothesis that these megaplanktivores become attracted to a prey biomass peak coinciding with their aggregation. Acoustic backscatter of the water column at 120 kHz and 333 kHz –a proxy for potential prey biomass –was continuously measured spanning the period prior to, during, and subsequent to the seasonal whale shark aggregations. No peak in acoustic backscatter was observed at the time of the aggregation. However, we observed a decrease in acoustic backscatter in the last days of deployment, which coincided the trailing end of whale shark season. Organisms forming the main scattering layer performed inverse diel vertical migration, with backscatter peaking at mid-depths during the day and in the deeper half of the water column at night. Target strength analyses suggested the backscatter was likely composed of fish larvae. Subsurface foraging behavior of the whale sharks within this aggregation has not been described, yet this study does not support the hypothesis that seasonal peaks in local whale shark abundance correspond to similar peaks in prey availability.

  3. Evaluation of the photon monitor backscatter in medical electron accelerators

    International Nuclear Information System (INIS)

    Zrenner, M.; Krieger, H.


    Background: Modern linear accelerators permit the use of irregular fields due to their flexible collimator systems with separately movable jaws or multileaf collimators. When using such irregular fields in the clinical practice output factors have to be corrected for enhanced backscatter to the dose monitor as compared with the conventional block shieldings. Methods: A method is presented to detect the monitor backscatter contributions to the output factor for irregular field settings. Results: The monitor backscatter factors have been measured using a telescopic device for 2 different treatment head geometries (Varian Clinac 2100C/D, General Electric Saturne 15) and for 3 photon radiation qualities (nominal energies X6, X18, X12). A method is introduced to calculate the monitor backscatter for arbitrary irregular treatment fields from the experimental data for square or rectangular fields. Conclusions: Besides the corrections for changes in phantom scatter and changes in the aperture, corrections for monitor backscatter have to be taken into account in many clinical cases. They can contribute up to more than 10% compared with the monitor values for free regular fields. (orig.) [de

  4. Measurement of backscatter factor for diagnostic radiology: methodology and uncertainties

    International Nuclear Information System (INIS)

    Rosado, P.H.G.; Nogueira, M.D.S.; Squair, P.L.; Da Silva, T.A.


    Full text: Backscatter factors were experimentally determined for the diagnostic X-ray qualities recommended by the International Electrotechnical Commission (IEC) for primary beams (RQR). Harshaw LiF-1 100H thermoluminescent dosemeters used for determining the backscatter were calibrated against an ionization chamber traceable to the National Metrology Laboratory. A 300mm x 300mm x 150mm PMMA slab phantom was used for deep-doses measurements. To perform the in-phantom measurements, the dosemeters were placed in the central axis of the x-ray beam at five different depths d in the phantom (5, 10, 15, 25 and 35 mm) upstream the beam direction. The typical combined standard uncertainty of the backscatter factor value was 6%. The main sources of uncertainties were the calibration procedure, the TLD dosimetry and the use of deep-dose curves. (Author)

  5. BATS - Backscattering And Time-of-flight Spectrometer

    International Nuclear Information System (INIS)

    Van Eijck, L.; Seydel, T.; Frick, B.; Schober, H.


    The new backscattering spectrometer IN16b will go into commissioning end 2011, providing in its final state about ten times higher count rate than its predecessor, IN16. Here we propose to increase its dynamic range by a factor of 7 with the TOF mode extension, BATS. This will make IN16b the leading high resolution backscattering spectrometer for incoherent quasi-elastic and inelastic neutron scattering; it will be competitive to the coarser resolution inverted geometry backscattering spectrometers that are being brought online at spallation sources. The increased dynamic range will extend the scope of science addressed on IN16b, generating considerable potential in fields such as the hydrogen economy (proton conduction, fuel cells, hydrogen storage), soft matter, biology and nano-science (nano-scale confinement, functionalized polymers). Such a large impact can be achieved using only a moderate investment. (authors)

  6. Determination of photon backscatter from several calibration phantoms

    International Nuclear Information System (INIS)

    McDonald, J.C.; Murphy, M.K.; Traub, R.J.


    American National Standards Institute (ANSI) and International Organization for Standardization (ISO) standards recommend the use of different phantoms for the calibration and proficiency testing of personnel dosimeters. The ANSI N13.11 standard describes a polymethyl methacrylate (PMMA) phantom measuring 30 x 30 x 15 cm. ISO draft standard 4037, part 3, recommends the use of a 30 x 30x 15-cm water-filled phantom with PMMA walls. An additional phantom with dimensions identical to the other two, but constructed of a tissue-equivalent plastic mixture, RS-1, was also used in these studies. The photon backscatter factor for these phantoms was compared to the International Commission on Radiation Units and Measurements (ICRU) reference phantom that has the same dimensions as the above mentioned phantoms, but has the elemental composition of ICRU four element tissue. Calculations of the photon backscatter over the range from 10 to 2,000 keV were performed using the MCNP 4A code for each of the phantoms. Measurements of the backscatter were carried out using thin-walled ionization chambers and thermoluminescent dosimeters that were exposed to x-ray beams With narrow energy spectra, either free-in-air or placed on the surface of the phantoms. The measurements and calculations were consistent and demonstrated that the ISO water filled phantom and the RS-1 plastic phantom generate photon backscatter that is nearly the same as that produced by the ICRU tissue reference phantom, but the backscatter from the PMMA phantom was up to about 8% higher. The conclusion drawn from these measurements is that either an ISO water-filled phantom or one constructed of RS-1 plastic would provide photon backscatter more comparable to an ICRU tissue reference phantom than a PMMA phantom

  7. Bruce Thompson: Adventures and advances in ultrasonic backscatter (United States)

    Margetan, Frank J.


    Over the course of his professional career Dr. R. Bruce Thompson published several hundred articles on non-destructive evaluation, the majority dealing with topics in ultrasonics. One longtime research interest of Dr. Thompson, with applications both to microstructure characterization and defect detection, was backscattered grain noise in metals. Over a 20 year period he led a revolving team of staff members and graduate students investigating various aspects of ultrasonic backscatter. As a member of that team I had the privilege of working along side Dr. Thompson for many years, serving as a sort of Dr. Watson to Bruce's Sherlock Holmes. This article discusses Dr. Thompson's general approaches to modeling backscatter, the research topics he chose to explore to systematically elucidate a better understanding of the phenomena, and the many contributions to the field achieved under his leadership. The backscatter work began in earnest around 1990, motivated by a need to improve inspections of aircraft engine components. At that time Dr. Thompson launched two research efforts. The first led to the heuristic Independent Scatterer Model which could be used to estimate the average grain noise level that would be seen in any given ultrasonic inspection. There the contribution from the microstructure was contained in a measureable parameter known as the Figure-of-Merit or FOM. The second research effort, spearheaded by Dr. Jim Rose, led to a formal relationship between FOM and details of the metal microstructure. The combination of the Independent Scattering Model and Rose's formalism provided a powerful tool for investigating backscatter in metals. In this article model developments are briefly reviewed and several illustrative applications are discussed. These include: the determination of grain size and shape from ultrasonic backscatter; grain noise variability in engine-titanium billets and forgings; and the design of ultrasonic inspection systems to improve defect

  8. Electron backscattering for process control in electron beam welding

    International Nuclear Information System (INIS)

    Ardenne, T. von; Panzer, S.


    A number of solutions to the automation of electron beam welding is presented. On the basis of electron backscattering a complex system of process control has been developed. It allows an enlarged imaging of the material's surface, improved adjustment of the beam focusing and definite focus positioning. Furthermore, both manual and automated positioning of the electron beam before and during the welding process has become possible. Monitoring of the welding process for meeting standard welding requirements can be achieved with the aid of a control quantity derived from the results of electronic evaluation of the high-frequency electron backscattering

  9. Astrophysical extended X-ray absorption fine-structure analysis

    International Nuclear Information System (INIS)

    Woo, J.W.; Forrey, R.C.; Cho, K.; Department of Physics and Division of Applied Sciences, Harvard University)


    We present an astrophysical extended X-ray absorption fine-structure (EXAFS) analysis (AEA) tool. The AEA tool is designed to generate a numerical model of the modification to the X-ray absorption coefficient due to the EXAFS phenomenon. We have constructed a complete database (elements up to the atomic number 92) of EXAFS parameters: central atom phase shift (2δ 1 ), backscattering phase shift (φ b ), and backscattering amplitude (F). Using the EXAFS parameter data base, the AEA tool can generate a numerical model of any compound when the atomic numbers of neighboring atoms and their distances to the central X-ray-absorbing atom are given. copyright 1997 The American Astronomical Society

  10. Detection of lower hybrid waves in the scrape-off layer of tokamak plasmas with microwave backscattering

    International Nuclear Information System (INIS)

    Baek, S. G.; Shiraiwa, S.; Parker, R. R.; Bonoli, P. T.; Marmar, E. S.; Wallace, G. M.; Lau, C.; Dominguez, A.; Kramer, G. J.


    Microwave backscattering experiments have been performed on the Alcator C-Mod tokamak in order to investigate the propagation of lower hybrid (LH) waves in reactor-relevant, high-density plasmas. When the line-averaged density is raised above 1 × 10 20 m –3 , lower hybrid current drive efficiency is found to be lower than expected [Wallace et al., Phys. Plasmas 19, 062505 (2012)] and LH power is thought to be dissipated at the plasma edge. Using a single channel (60 GHz) ordinary-mode (O-mode) reflectometer system, we demonstrate radially localized LH wave measurements in the scrape-off layer of high density plasmas (n ¯ e  ≳ 0.9×10 20  m −3 ). Measured backscattered O-mode power varies depending on the magnetic field line mapping, suggesting the resonance cone propagation of LH waves. Backscattered power is also sensitive to variations in plasma density and the launched parallel refractive index of the LH waves. LH ray-tracing simulations have been carried out to interpret the observed variations. To understand the measured LH waves in regions not magnetically connected to the launcher, two hypotheses are examined. One is the weak single pass absorption and the other is scattering of LH waves by non-linear effects

  11. Lattice constant measurement from electron backscatter diffraction patterns

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.


    Kikuchi bands in election backscattered diffraction patterns (EBSP) contain information about lattice constants of crystallographic samples that can be extracted via the Bragg equation. An advantage of lattice constant measurement from EBSPs over diffraction (XRD) is the ability to perform local ...

  12. Power Control for Passive QAM Multisensor Backscatter Communication Systems

    Directory of Open Access Journals (Sweden)

    Shengbo Hu


    Full Text Available To achieve good quality of service level such as throughput, power control is of great importance to passive quadrature amplitude modulation (QAM multisensor backscatter communication systems. First, we established the RF energy harvesting model and gave the energy condition. In order to minimize the interference of subcarriers and increase the spectral efficiency, then, the colocated passive QAM backscatter communication signal model is presented and the nonlinear optimization problems of power control are solved for passive QAM backscatter communication systems. Solutions include maximum and minimum access interval, the maximum and minimum duty cycle, and the minimal RF-harvested energy under the energy condition for node operating. Using the solutions above, the maximum throughput of passive QAM backscatter communication systems is analyzed and numerical calculation is made finally. Numerical calculation shows that the maximal throughput decreases with the consumed power and the number of sensors, and the maximum throughput is decreased quickly with the increase of the number of sensors. Especially, for a given consumed power of sensor, it can be seen that the throughput decreases with the duty cycle and the number of sensors has little effect on the throughput.

  13. Method and Apparatus for Computed Imaging Backscatter Radiography (United States)

    Shedlock, Daniel (Inventor); Meng, Christopher (Inventor); Sabri, Nissia (Inventor); Dugan, Edward T. (Inventor); Jacobs, Alan M. (Inventor)


    Systems and methods of x-ray backscatter radiography are provided. A single-sided, non-destructive imaging technique utilizing x-ray radiation to image subsurface features is disclosed, capable of scanning a region using a fan beam aperture and gathering data using rotational motion.

  14. On the maximum backscattering cross section of passive linear arrays

    DEFF Research Database (Denmark)

    Solymar, L.; Appel-Hansen, Jørgen


    The maximum backscattering cross section of an equispaced linear array connected to a reactive network and consisting of isotropic radiators is calculated forn = 2, 3, and 4 elements as a function of the incident angle and of the distance between the elements. On the basis of the results obtained...

  15. About the information depth of backscattered electron imaging

    Czech Academy of Sciences Publication Activity Database

    Piňos, Jakub; Mikmeková, Šárka; Frank, Luděk


    Roč. 266, č. 3 (2017), s. 335-342 ISSN 0022-2720 Institutional support: RVO:68081731 Keywords : backscattered electrons * information depth * penetration of electrons Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Materials engineering Impact factor: 1.692, year: 2016

  16. Ultrasonic Characterization of Tissues via Backscatter Frequency Dependence

    DEFF Research Database (Denmark)

    Stetson, Paul F.; Sommer, F.G.


    Phantom and patient studies were performed to assess the potential of backscatter frequency dependence as a useful parameter for tissue characterization. A commercial phased-array ultrasonic scanner was adapted to allow digitization of the intermediate-frequency ultrasonic data, Studies of agar p...

  17. Impact of diurnal variation in vegetation water content on radar backscatter from maize during water stress

    NARCIS (Netherlands)

    Van Emmerik, T.H.M.; Dunne, S.C.; Judge, J.; van de Giesen, N.C.


    Microwave backscatter from vegetated surfaces is influenced by vegetation structure and vegetation water content (VWC), which varies with meteorological conditions and moisture in the root zone. Radar backscatter observations are used for many vegetation and soil moisture monitoring applications

  18. Airborne Measurements of Rain and the Ocean Surface Backscatter Response at C- and Ku-band

    National Research Council Canada - National Science Library

    Fernandez, Daniel E; Chang, Paul S; Carswell, James R; Contreras, Robert F; Frasier, Stephen J


    ...) and the Simultaneous Frequency Microwave Radiometer (SFMR). IWRAP is a dual-band (C- and Ku), dual-polarized pencilbeam airborne radar that profiles the volume backscatter and Doppler velocity from rain and that also measures the ocean backscatter response...

  19. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen


    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  20. Multibeam Backscatter Data for Selected U.S. Locations in the Pacific (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry for selected U.S. locations in the Pacific. The backscatter datasets include data collected using the...

  1. Backscatter, anisotropy, and polarization of solar hard X-rays

    International Nuclear Information System (INIS)

    Bai, T.; Ramaty, R.


    Hard X-rays incident upon the photosphere with energies > or approx. =15 keV have high probabilities of backscatter due to Compton collisions with electrons. This effect has a strong influence on the spectrum, intensity, and polarization of solar hard X-rays - especially for anisotropic models in which the primary X-rays are emitted predominantly toward the photosphere. We have carried out a detailed study of X-ray backscatter, and we have investigated the interrelated problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter in a coherent fashion. The results of this study are compared with observational data. Because of the large contribution from backscatter, for an anisotropic primary X-ray source which is due to bremsstrahlung of accelerated electrons moving predominantly down toward the photosphere, the observed X-ray flux around 30 keV does not depend significantly on the position of flare on the Sun. For such an anisotropic source, the X-ray spectrum observed in the 15-50 keV range becomes steeper with the increasing heliocentric angle of the flare. These results are compatible with the data. The degree of polarization of the sum of the primary and reflected X-rays with energies between about 15 and 30 keV can be very large for anisotropic primary X-ray sources, but it is less than about 4% for isotropic sources. We also discuss the characteristics of the brightness distribution of the X-ray albedo patch created by the Compton backscatter. The height and anisotropy of the primary hard X-ray source might be inferred from the study of the albedo patch

  2. Drivers of ASCAT C band backscatter variability in the dry snow zone of Antarctica

    NARCIS (Netherlands)

    Fraser, Alexander D.; Nigro, Melissa A.; Ligtenberg, Stefan R. M.; Legresy, Benoit; Inoue, Mana; Cassano, John J.; Munneke, Peter Kuipers; Lenaerts, Jan T. M.; Young, Neal W.; Treverrow, Adam; Van Den Broeke, Michiel; Enomot, Hiroyuki


    C band backscatter parameters contain information about the upper snowpack/firn in the dry snow zone. The wide incidence angle diversity of the Advanced Scatterometer (ASCAT) gives unprecedented characterisation of backscatter anisotropy, revealing the backscatter response to climatic forcing. The A

  3. Use of acoustic backscatter to estimate continuous suspended sediment and phosphorus concentrations in the Barton River, northern Vermont, 2010-2013 (United States)

    Medalie, Laura; Chalmers, Ann T.; Kiah, Richard G.; Copans, Benjamin


    The U.S. Geological Survey, in cooperation with the Vermont Department of Environmental Conservation, investigated the use of acoustic backscatter to estimate concentrations of suspended sediment and total phosphorus at the Barton River near Coventry, Vermont. The hypothesis was that acoustic backscatter—the reflection of sound waves off objects back to the source from which they came—measured by an acoustic Doppler profiler (ADP) and recorded as ancillary data for the calculation of discharge, also could be used to generate a continuous concentration record of suspended sediment and phosphorus at the streamgage, thereby deriving added value from the instrument. Suspended-sediment and phosphorus concentrations are of particular interest in Vermont, where impairment of surface waters by suspended sediments and phosphorus is a major concern. Regression models for estimating suspended-sediment concentrations (SSCs) and total phosphorus concentrations evaluated several independent variables: measured backscatter (MB), water-corrected backscatter (WCB), sediment-corrected backscatter (SCB), discharge, fluid-absorption coefficient, sediment-driven acoustic attenuation coefficient, and discharge hysteresis. The best regression equations for estimating SSC used backscatter as the predictor, reflecting the direct relation between acoustic backscatter and SSC. Backscatter was a better predictor of SSC than discharge in part because hysteresis between SSC and backscatter was less than for SSC and discharge. All three backscatter variables—MB, WCB, and SCB—performed equally as predictors of SSC and phosphorus concentrations at the Barton River site. The similar abilities to predict SSC among backscatter terms may partially be attributed to the low values and narrow range of the sediment-driven acoustic attenuation in the Barton River. The regression based on SCB was selected for estimating SSC because it removes potential bias caused by attenuation and temperature

  4. Retrieval of Ocean Subsurface Particulate Backscattering Coefficient from Space-Borne CALIOP Lidar Measurement (United States)

    Lu, Xiaomei; Hu, Yongxiang; Pelon, Jacques; Trepte, Chip; Liu, Katie; Rodier, Sharon; Zeng, Shan; Luckher, Patricia; Verhappen, Ron; Wilson, Jamie; hide


    A new approach has been proposed to determine ocean subsurface particulate backscattering coefficient bbp from CALIOP 30deg off-nadir lidar measurements. The new method also provides estimates of the particle volume scattering function at the 180deg scattering angle. The CALIOP based layer-integrated lidar backscatter and particulate backscattering coefficients are compared with the results obtained from MODIS ocean color measurements. The comparison analysis shows that ocean subsurface lidar backscatter and particulate backscattering coefficient bbp can be accurately obtained from CALIOP lidar measurements, thereby supporting the use of space-borne lidar measurements for ocean subsurface studies.

  5. Validation Test of Geant4 Simulation of Electron Backscattering

    CERN Document Server

    Kim, Sung Hun; Basaglia, Tullio; Han, Min Cheol; Hoff, Gabriela; Kim, Chan Hyeong; Saracco, Paolo


    Backscattering is a sensitive probe of the accuracy of electron scattering algorithms implemented in Monte Carlo codes. The capability of the Geant4 toolkit to describe realistically the fraction of electrons backscattered from a target volume is extensively and quantitatively evaluated in comparison with experimental data retrieved from the literature. The validation test covers the energy range between approximately 100 eV and 20 MeV, and concerns a wide set of target elements. Multiple and single electron scattering models implemented in Geant4, as well as preassembled selections of physics models distributed within Geant4, are analyzed with statistical methods. The evaluations concern Geant4 versions from 9.1 to 10.1. Significant evolutions are observed over the range of Geant4 versions, not always in the direction of better compatibility with experiment. Goodness-of-fit tests complemented by categorical analysis tests identify a configuration based on Geant4 Urban multiple scattering model in Geant4 vers...

  6. Scattering center models of backscattering waves by dielectric spheroid objects. (United States)

    Guo, Kun-Yi; Han, Xiao-Zhe; Sheng, Xin-Qing


    Scattering center models provide a simple and effective way of describing the complex electromagnetic scattering phenomena of targets and have been successfully applied in radar applications. However, the existing models are limited to conducting objects. Numerical results show that scattering centers of dielectric objects are far more complex than conducting objects and most of them are distributed beyond the object. For the lossless and low-loss media, the major scattering contributions to total fields are surface waves and multiple internal reflections rather than the direct reflection. Concise scattering center models for backscattering from dielectric spheroid objects are proposed in this work, which can characterize the backscattered waves by scattering centers with sparse and physical parameters. Good agreement has been demonstrated between the high resolution range profiles simulated by this model with those obtained by Mie series and the full wave numerical method.

  7. RFID tag modification for full depth backscatter modulation (United States)

    Scott, Jeffrey Wayne [Pasco, WA; Pratt, Richard M [Richland, WA


    A modulated backscatter radio frequency identification device includes a diode detector configured to selectively modulate a reply signal onto an incoming continuous wave; communications circuitry configured to provide a modulation control signal to the diode detector, the diode detector being configured to modulate the reply signal in response to be modulation control signal; and circuitry configured to increase impedance change at the diode detector which would otherwise not occur because the diode detector rectifies the incoming continuous wave while modulating the reply signal, whereby reducing the rectified signal increases modulation depth by removing the reverse bias effects on impedance changes. Methods of improving depth of modulation in a modulated backscatter radio frequency identification device are also provided.

  8. Lidar extinction-to-backscatter ratio of the ocean. (United States)

    Churnside, James H; Sullivan, James M; Twardowski, Michael S


    Bio-optical models are used to develop a model of the lidar extinction-to-backscatter ratio applicable to oceanographic lidar. The model is based on chlorophyll concentration, and is expected to be valid for Case 1 waters. The limiting cases of narrow- and wide-beam lidars are presented and compared with estimates based on in situ optical measurements. Lidar measurements are also compared with the model using in situ or satellite estimates of chlorophyll concentration. A modified lidar ratio is defined, in which the properties of pure sea water are removed. This modified ratio is shown to be nearly constant for wide-beam lidar operating in low-chlorophyll waters, so accurate inversion to derive extinction and backscattering is possible under these conditions. This ratio can also be used for lidar calibration.

  9. Application of neutron backscatter techniques to level measurement problems

    International Nuclear Information System (INIS)

    Leonardi-Cattolica, A.M.; McMillan, D.H.; Telfer, A.; Griffin, L.H.; Hunt, R.H.


    We have designed and built portable level detectors and fixed level monitors based on neutron scattering and detection principles. The main components of these devices, which we call neutron backscatter gauges, are a neutron emitting radioisotope, a neutron detector, and a ratemeter. The gauge is a good detector for hydrogen but is much less sensitive to most other materials. This allows level measurements of hydrogen bearing materials, such as hydrocarbons, to be made through the walls of metal vessels. Measurements can be made conveniently through steel walls which are a few inches thick. We have used neutron backscatter gauges in a wide variety of level measurement applications encountered in the petrochemical industry. In a number of cases, the neutron techniques have proven to be superior to conventional level measurement methods, including gamma ray methods

  10. Bottom Backscattering Strengths Measured in Shallow and Deep Water (United States)


    to the MF results. 18-01-2017 Memorandum Report Bottom scattering Bottom scattering strength Reverberation Underwater acoustics Active sonar August...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/7160--17-9701 Bottom Backscattering Strengths Measured in Shallow and Deep Water January...18, 2017 Approved for public release; distribution is unlimited. RogeR C. gauss edwaRd L. Kunz Joseph M. FiaLKowsKi RiChaRd Menis Acoustic Signal

  11. Myocardial ultrasonic backscatter in hypertension: relation to aldosterone and endothelin. (United States)

    Kozàkovà, Michaela; Buralli, Simona; Palombo, Carlo; Bernini, Giampaolo; Moretti, Angelica; Favilla, Stefania; Taddei, Stefano; Salvetti, Antonio


    A disproportionate accumulation of fibrillar collagen is a characteristic feature of hypertensive heart disease, but the extent of myocardial fibrosis may differ in different models of hypertension. In experimental studies, aldosterone and endothelins emerge as important determinants of myocardial fibrosis. Changes in myocardial extracellular matrix and collagen deposition can be estimated noninvasively by analysis of the ultrasonic backscatter signal, which arises from tissue heterogeneity within the myocardium and describes myocardial texture. This study was designed to investigate the relations between myocardial integrated backscatter and circulating aldosterone and immunoreactive endothelin in human hypertension. The study population consisted of 56 subjects: 14 healthy normotensive volunteers and 42 hypertensive patients (14 with primary aldosteronism, 7 with renovascular hypertension, and 21 with essential hypertension). The patients with essential and secondary hypertension were matched for age, gender, body mass index, and blood pressure. Myocardial integrated backscatter at diastole was 19.8+/-2.0 and 20.8+/-2.9 decibels in normotensive control subjects and patients with essential hypertension and significantly higher in patients with primary aldosteronism (27.4+/-3.8 decibels, P<0.01) and renovascular hypertension (26.8+/-4.8 decibels, P<0.01). In the population as a whole, as well as in the hypertensive subpopulation, myocardial integrated backscatter was directly related to plasma aldosterone (r=0.73 and 0.71, P<0.01 for both) and immunoreactive endothelin (r=0.60 and 0.56, P<0.01 for both). The data of this study suggest that in human hypertension, circulating aldosterone and immunoreactive endothelin may induce alterations in left ventricular myocardial texture, possibly related to increased myocardial collagen content.

  12. High-precision thickness measurements using beta backscatter

    International Nuclear Information System (INIS)

    Heckman, R.V.


    A two-axis, automated fixture for use with a high-intensity Pm-147 source and a photomultiplier-scintillation beta-backscatter probe for making thickness measurements has been designed and built. A custom interface was built to connect the system to a minicomputer, and software was written to position the tables, control the probe, and make the measurements. Measurements can be made in less time with much greater precision than by the method previously used

  13. Time of flight spectrometry in heavy ions backscattering analysis

    International Nuclear Information System (INIS)

    Chevarier, A.; Chevarier, N.


    Time of flight spectrometry for backscattering analysis of MeV heavy ions is proposed. The capabilities and limitations of this method are investigated. Depth and mass resolution obtained in measurements of oxide films thickness as well as in GaAs layers analysis are presented. The importance of minimizing pile-up without significant loss of resolution by use of an adequate absorber set just in front of the rear detector is underlined

  14. Users guide to the HELIOS backscattering spectrometer (BSS)

    International Nuclear Information System (INIS)

    Bunce, L.J.


    The BSS is a backscattering spectrometer installed on the Harwell 136 Mev electron linear accelerator, HELIOS. A general description of the instrument is given, along with the time of flight scales, and the run and sample changer control units. The sample environment, vacuum system and detectors of the BSS are described, as well as the preparation, starting and running of an experiment using the BSS. (UK)

  15. Multiple scattering wavelength dependent backscattering of kaolin dust in the IR: Measurements and theory (United States)

    Ben-David, Avishai


    Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.

  16. Ion backscattering techniques applied in materials science research

    International Nuclear Information System (INIS)

    Sood, D.K.


    The applications of Ion Backscattering Technique (IBT) to material analysis have expanded rapidly during the last decade. It is now regarded as an analysis tool indispensable for a versatile materials research program. The technique consists of simply shooting a beam of monoenergetic ions (usually 4 He + ions at about 2 MeV) onto a target, and measuring their energy distribution after backscattering at a fixed angle. Simple Rutherford scattering analysis of the backscattered ion spectrum yields information on the mass, the absolute amount and the depth profile of elements present upto a few microns of the target surface. The technique is nondestructive, quick, quantitative and the only known method of analysis which gives quantitative results without recourse to calibration standards. Its major limitations are the inability to separate elements of similar mass and a complete absence of chemical-binding information. A typical experimental set up and spectrum analysis have been described. Examples, some of them based on the work at the Bhabha Atomic Research Centre, Bombay, have been given to illustrate the applications of this technique to semiconductor technology, thin film materials science and nuclear energy materials. Limitations of IBT have been illustrated and a few remedies to partly overcome these limitations are presented. (auth.)

  17. Full aperture backscatter diagnostic for the NIF laser facility (abstract)

    International Nuclear Information System (INIS)

    Sewall, Noel; Lewis, Izzy; Kirkwood, Robert; Moody, John; Celeste, John


    The current schemes for achieving ignition on the National Ignition Facility require efficient coupling of energy from 192 laser beams to the deuterium--tritium fuel capsule. Each laser beam must propagate through a long scalelength plasma region before being converted to x rays (indirect drive) or being absorbed on the capsule (direct drive). Laser-plasma instabilities such as stimulated Brillouin and stimulated Raman scattering (SBS and SRS) will scatter a fraction of the incident laser energy out of the target leading to an overall reduction in the coupling efficiency. It is important to measure the character of this scattered light in order to understand it and to develop methods for reducing it to acceptable levels. We are designing a system called the full aperature backscatter diagnostic with the capability to measure the time-dependent amplitude and spectral content of the light which is backscattered through the incident beam focusing optic. The backscattered light will be collected over about 85% of the full beam aperture and separated into the SBS wavelength band (348--354 nm) and the SRS wavelength band (400--700 nm). Spectrometers coupled to streak cameras will provide time-resolved spectra for both scattered light components. The scattered light amplitude will be measured with fast and slow diodes. The entire system will be routinely calibrated. Analysis of the data will provide important information for reducing scattered power, achieving power balance, and finally achieving ignition

  18. A Review of Point-Wise Motion Tracking Algorithms for Fetal Magnetic Resonance Imaging. (United States)

    Chikop, Shivaprasad; Koulagi, Girish; Kumbara, Ankita; Geethanath, Sairam


    We review recent feature-based tracking algorithms as applied to fetal magnetic resonance imaging (MRI). Motion in fetal MRI is an active and challenging area of research, but the challenge can be mitigated by strategies related to patient setup, acquisition, reconstruction, and image processing. We focus on fetal motion correction through methods based on tracking algorithms for registration of slices with similar anatomy in multiple volumes. We describe five motion detection algorithms based on corner detection and region-based methods through pseudocodes, illustrating the results of their application to fetal MRI. We compare the performance of these methods on the basis of error in registration and minimum number of feature points required for registration. Harris, a corner detection method, provides similar error when compared to the other methods and has the lowest number of feature points required at that error level. We do not discuss group-wise methods here. Finally, we attempt to communicate the application of available feature extraction methods to fetal MRI.

  19. Point-wise and whole-field laser speckle intensity fluctuation measurements applied to botanical specimens (United States)

    Zhao, Yang; Wang, Junlan; Wu, Xiaoping; Williams, Fred W.; Schmidt, Richard J.


    Based on multi-scattering speckle theory, the speckle fields generated by plant specimens irradiated by laser light have been studied using a pointwise method. In addition, a whole-field method has been developed with which entire botanical specimens may be studied. Results are reported from measurements made on tomato and apple fruits, orange peel, leaves of tobacco seedlings, leaves of shihu seedlings (a Chinese medicinal herb), soy-bean sprouts, and leaves from an unidentified trailing houseplant. Although differences where observed in the temporal fluctuations of speckles that could be ascribed to differences in age and vitality, the growing tip of the bean sprout and the shihu seedling both generated virtually stationary speckles such as were observed from boiled orange peel and from localised heat-damaged regions on apple fruit. Our results suggest that both the identity of the botanical specimen and the site at which measurements are taken are likely to critically affect the observation or otherwise of temporal fluctuations of laser speckles.

  20. HF coherent backscatter in the ionosphere: In situ measurements of SuperDARN backscatter with e-POP RRI (United States)

    Perry, G. W.; James, H. G.; Hussey, G. C.; Howarth, A. D.; Yau, A. W.


    We report in situ polarimetry measurements of HF scattering obtained by the Enhanced Polar Outflow Probe (e-POP) Radio Receiver Instrument (RRI) during a coherent backscatter scattering event detected by the Saskatoon Super Dual Auroral Radar Network (SuperDARN). On April 1, 2015, e-POP conducted a 4 minute coordinated experiment with SuperDARN Saskatoon, starting at 3:38:44 UT (21:38:44 LT). Throughout the experiment, SuperDARN was transmitting at 17.5 MHz and e-POP's ground track moved in a northeastward direction, along SuperDARN's field-of-view, increasing in altitude from 331 to 352 km. RRI was tuned to 17.505 MHz, and recorded nearly 12,000 SuperDARN radar pulses during the experiment. In the first half of the experiment, radar pulses recorded by RRI were "well behaved": they retained their transmitted amplitude envelope, and their pulse-to-pulse polarization characteristics were coherent - Faraday rotation was easily measured. During the second half of the experiment the pulses showed clear signs of scattering: their amplitude envelopes became degraded and dispersed, and their pulse-to-pulse polarization characteristics became incoherent - Faraday rotation was difficult to quantify. While these pulses were being received by RRI, SuperDARN Saskatoon detected a latitudinal band of coherent backscatter at e-POP's location, indicating that the scattered pulses measured by RRI may be a signature of HF backscatter. In this presentation, we will outline the polarimetric details of the scattered pulses, and provide an analytic interpretation of RRI's measurements to give new insight into the nature of HF coherent backscatter mechanism taking place in the terrestrial ionosphere.

  1. Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas (United States)

    Roche, Marc; Degrendele, Koen; Vrignaud, Christophe; Loyer, Sophie; Le Bas, Tim; Augustin, Jean-Marie; Lurton, Xavier


    The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition and processing parameters. If all these conditions are met, stability check and relative calibration of a system are possible by comparison with the averaged backscatter values for the area. Based on a common multibeam echosounder and sampling campaign completed by available bathymetric and backscatter time series, the suitability as a backscatter reference area of three different candidates was evaluated. Two among them, Carré Renard and Kwinte, prove to be excellent choices, while the third one, Western Solent, lacks sufficient data over time, but remains a valuable candidate. The case studies and the available backscatter data on these areas prove the applicability of this method. The expansion of the number of commonly used reference areas and the growth of the number of multibeam echosounder controlled thereon could greatly contribute to the further development of quantitative applications based on multibeam echosounder backscatter measurements.

  2. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Rosado, Paulo Henrique Goncalves


    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm 3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133 Ba, 241 Am and 57 Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and

  3. Assessment of Multibeam Backscatter Texture Analysis for Seafloor Sediment Classification (United States)

    Samsudin, S. A.; Hasan, R. C.


    Recently, there have been many debates to analyse backscatter data from multibeam echosounder system (MBES) for seafloor classifications. Among them, two common methods have been used lately for seafloor classification; (1) signal-based classification method which using Angular Range Analysis (ARA) and Image-based texture classification method which based on derived Grey Level Co-occurrence Matrices (GLCMs). Although ARA method could predict sediment types, its low spatial resolution limits its use with high spatial resolution dataset. Texture layers from GLCM on the other hand does not predict sediment types, but its high spatial resolution can be useful for image analysis. The objectives of this study are; (1) to investigate the correlation between MBES derived backscatter mosaic textures with seafloor sediment type derived from ARA method, and (2) to identify which GLCM texture layers have high similarities with sediment classification map derived from signal-based classification method. The study area was located at Tawau, covers an area of 4.7 km2, situated off the channel in the Celebes Sea between Nunukan Island and Sebatik Island, East Malaysia. First, GLCM layers were derived from backscatter mosaic while sediment types (i.e. sediment map with classes) was also constructed using ARA method. Secondly, Principal Component Analysis (PCA) was used determine which GLCM layers contribute most to the variance (i.e. important layers). Finally, K-Means clustering algorithm was applied to the important GLCM layers and the results were compared with classes from ARA. From the results, PCA has identified that GLCM layers of Correlation, Entropy, Contrast and Mean contributed to the 98.77 % of total variance. Among these layers, GLCM Mean showed a good agreement with sediment classes from ARA sediment map. This study has demonstrated different texture layers have different characterisation factors for sediment classification and proper analysis is needed before

  4. Laboratory investigations of mineral dust near-backscattering depolarization ratios

    International Nuclear Information System (INIS)

    Järvinen, E.; Kemppinen, O.; Nousiainen, T.; Kociok, T.; Möhler, O.; Leisner, T.; Schnaiter, M.


    Recently, there has been increasing interest to derive the fractions of fine- and coarse-mode dust particles from polarization lidar measurements. For this, assumptions of the backscattering properties of the complex dust particles have to be made either by using empirical data or particle models. Laboratory measurements of dust backscattering properties are important to validate the assumptions made in the lidar retrievals and to estimate their uncertainties. Here, we present laboratory measurements of linear and circular near-backscattering (178°) depolarization ratios of over 200 dust samples measured at 488 and 552 nm wavelengths. The measured linear depolarization ratios ranged from 0.03 to 0.36 and were strongly dependent on the particle size. The strongest size-dependence was observed for fine-mode particles as their depolarization ratios increased almost linearly with particle median diameter from 0.03 to 0.3, whereas the coarse-mode particle depolarization values stayed rather constant with a mean linear depolarization ratio of 0.27. The depolarization ratios were found to be insensitive to the dust source region or thin coating of the particles or to changes in relative humidity. We compared the measurements with results of three different scattering models. With certain assumptions for model particle shape, all the models were capable of correctly describing the size-dependence of the measured dust particle, albeit the model particles significantly differed in composition, shape and degree of complexity. Our results show potential for distinguishing the dust fine- and coarse-mode distributions based on their depolarization properties and, thus, can serve the lidar community as an empirical reference.

  5. Concentration measurement of yeast suspensions using high frequency ultrasound backscattering. (United States)

    Elvira, Luis; Vera, Pedro; Cañadas, Francisco Jesús; Shukla, Shiva Kant; Montero, Francisco


    This work proposes the use of an ultrasound based technique to measure the concentration of yeasts in liquid suspension. This measurement was achieved by the detection and quantification of ultrasonic echoes backscattered by the cells. More specifically, the technique was applied to the detection and quantification of Saccharomyces cerevisiae. A theoretical approach was proposed to get the average density and sound speed of the yeasts, which were found to be 1116 kg/m(3) and 1679 m/s, respectively. These parameters were needed to model the waves backscattered by each single cell. A pulse-echo arrangement working around 50 MHz, being able to detect echoes from single yeasts was used to characterize experimentally yeast solutions from 10(2) to 10(7)cells/ml. The Non-negative Matrix Factorization denoising technique was applied for data analysis. This technique required a previous learning of the spectral patterns of the echoes reflected from yeasts in solution and the base noise from the liquid medium. Comparison between pulse correlation (without denoising) and theoretical and experimental pattern learning was made to select the best signal processing. A linear relation between ultrasound output and concentration was obtained with correlation coefficient R(2)=0.996 for the experimental learning. Concentrations from 10(4) to 10(7)cells/ml were detected above the base noise. These results show the viability of using the ultrasound backscattering technique to detect yeasts and measure their concentration in liquid cultures, improving the sensitivity obtained using spectrophotometric methods by one order of magnitude. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Laboratory investigations of mineral dust near-backscattering depolarization ratios (United States)

    Järvinen, E.; Kemppinen, O.; Nousiainen, T.; Kociok, T.; Möhler, O.; Leisner, T.; Schnaiter, M.


    Recently, there has been increasing interest to derive the fractions of fine- and coarse-mode dust particles from polarization lidar measurements. For this, assumptions of the backscattering properties of the complex dust particles have to be made either by using empirical data or particle models. Laboratory measurements of dust backscattering properties are important to validate the assumptions made in the lidar retrievals and to estimate their uncertainties. Here, we present laboratory measurements of linear and circular near-backscattering (178°) depolarization ratios of over 200 dust samples measured at 488 and 552 nm wavelengths. The measured linear depolarization ratios ranged from 0.03 to 0.36 and were strongly dependent on the particle size. The strongest size-dependence was observed for fine-mode particles as their depolarization ratios increased almost linearly with particle median diameter from 0.03 to 0.3, whereas the coarse-mode particle depolarization values stayed rather constant with a mean linear depolarization ratio of 0.27. The depolarization ratios were found to be insensitive to the dust source region or thin coating of the particles or to changes in relative humidity. We compared the measurements with results of three different scattering models. With certain assumptions for model particle shape, all the models were capable of correctly describing the size-dependence of the measured dust particle, albeit the model particles significantly differed in composition, shape and degree of complexity. Our results show potential for distinguishing the dust fine- and coarse-mode distributions based on their depolarization properties and, thus, can serve the lidar community as an empirical reference.

  7. Combined backscatter and transmission method for nuclear density gauge

    Directory of Open Access Journals (Sweden)

    Golgoun Seyed Mohammad


    Full Text Available Nowadays, the use of nuclear density gauges, due to the ability to work in harsh industrial environments, is very common. In this study, to reduce error related to the ρ of continuous measuring density, the combination of backscatter and transmission are used simultaneously. For this reason, a 137Cs source for Compton scattering dominance and two detectors are simulated by MCNP4C code for measuring the density of 3 materials. Important advantages of this combined radiometric gauge are diminished influence of μ and therefore improving linear regression.

  8. Lattice constant measurement from electron backscatter diffraction patterns

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.


    Kikuchi bands in election backscattered diffraction patterns (EBSP) contain information about lattice constants of crystallographic samples that can be extracted via the Bragg equation. An advantage of lattice constant measurement from EBSPs over diffraction (XRD) is the ability to perform local...... is approximately 0.04 Å. Studying Kikuchi band size dependence of the measurement precision shows that the measurement error decays with increasing band size (i.e. decreasing lattice constant). However, in practice, the sharpness of wide bands tends to be low due to their low intensity, thus limiting...

  9. Oscillations in the spectrum of nonlinear Thomson-backscattered radiation

    Directory of Open Access Journals (Sweden)

    C. A. Brau


    Full Text Available When an electron beam collides with a high-intensity laser beam, the spectrum of the nonlinear Thomson scattering in the backward direction shows strong oscillations like those in the spectrum of an optical klystron. Laser gain on the backward Thomson scattering is estimated using the Madey theorem, and the results suggest that Thomson-backscatter free-electron lasers are possible at wavelengths extending to the far uv using a terawatt laser beam from a chirped-pulse amplifier and a high-brightness electron beam from a needle cathode.

  10. Photoneutron production with the Laser-Compton backscattered photons

    Energy Technology Data Exchange (ETDEWEB)

    Toyokawa, Hiroyuki; Ohgaki, Hideaki; Sugiyama, Suguru; Mikado, Tomohisa; Yamada, Kawakatsu; Suzuki, Ryoichi; Ohdaira, Toshiyuki; Sei, Norihiro; Chiwaki, Mitsukuni [Electrotechnical Laboratory, Tsukuba, Ibaraki (Japan)


    A method to produce quasi-monoenergetic photoneutrons for detector calibration was examined. The photoneutrons were produced with a photo-induced neutron emission of a {sup 9}Be using the Laser-Compton backscattered photons. Because the photon energy is continuously tunable, neutrons with various energies are obtained. Yield of the neutrons was measured with a liquid scintillation detector at the photon energies from 1651 keV to 3019 keV. Neutron yield at around the threshold energy for the {sup 9}Be ({gamma}, n) reaction was measured by changing the photon energy in a 10 keV step. (author)

  11. Bulk media assay using backscattered Pu-Be neutrons

    CERN Document Server

    Csikai, J


    Spectral yields of elastically backscattered Pu-Be neutrons measured for graphite, water, polyethylene, liquid nitrogen, paraffin oil, SiO sub 2 , Al, Fe, and Pb slabs show a definite correlation with the energy dependence of the elastic scattering cross sections, sigma sub E sub L (E sub n). The C, N and O can be identified by the different structures in their sigma sub E sub L (E sub n) functions. The integrated spectral yields versus thickness exhibit saturation for each sample. The interrogated volume is limited by the presence of hydrogen in the sample. (author)

  12. Application of electron back-scatter diffraction to texture research

    International Nuclear Information System (INIS)

    Randle, V.


    The application of electron back-scatter diffraction (EBSD) to materials research is reviewed. A brief history of the technique is given, followed by a description of present-day operation. The methodology of 'microtexture', i.e. spatially specific orientations, is described and recent examples of its application using EBSD are given, in particular to interstitial-free steel processing, growth of phases in a white iron and grain boundary phenomena in a superplastic alloy. The advantages and disadvantages of EBSD compared to use of X-rays for texture determination are discussed in detail

  13. Quantifying Fish Backscattering using SONAR Instrument and Kirchhoff Ray Mode (KRM) Model (United States)

    Manik, Henry M.


    Sonar instrument was used to study backscattering from tuna fish. Extraction of target strength, incidence angle, and frequency dependence of the backscattered signal for individual scatterer was important for biological information. For this purpose, acoustic measurement of fish backscatter was conducted in the laboratory. Characteristics and general trends of the target strength of fish with special reference to tuna fish were investigated by using a Kirchhoff Ray Mode (KRM) model. Backscattering strength were calculated for the KRM having typical morphological and physical parameters of actual fish. Those backscattering amplitudes were shown as frequency, body length, backscattering patterns, the density and sound speed dependences, and orientation dependence. These results were compared with experimentally measured target strength data and good agreement was found. Measurement and model showed the target strength from the fish are depend on the presence of swimbladder. Target Strength increase with increasing the frequency and fish length.

  14. Extinction-to-Backscatter Ratios of Saharan Dust Layers Derived from In-Situ Measurements and CALIPSO Overflights During NAMMA (United States)

    Omar, Ali H.; Liu, Zhaoyan; Vaughan, Mark A.; Hu, Yongxiang; Ismail, Syed; Powell, Kathleen A.; Winker, David M.; Trepte, Charles R.; Anderson, Bruce E.


    We determine the aerosol extinction-to-backscatter (Sa) ratios of dust using airborne in-situ measurements of microphysical properties, and CALIPSO observations during the NASA African Monsoon Multidisciplinary Analyses (NAMMA). The NAMMA field experiment was conducted from Sal, Cape Verde during Aug-Sept 2006. Using CALIPSO measurements of the attenuated backscatter of lofted Saharan dust layers, we apply the transmittance technique to estimate dust Sa ratios at 532 nm and a 2-color method to determine the corresponding 1064 nm Sa. Using this method, we found dust Sa ratios of 39.8 plus or minus 1.4 sr and 51.8 plus or minus 3.6 sr at 532 nm and 1064 nm, respectively. Secondly, Sa ratios at both wavelengths is independently calculated using size distributions measured aboard the NASA DC-8 and estimates of Saharan dust complex refractive indices applied in a T-Matrix scheme. We found Sa ratios of 39.1 plus or minus 3.5 sr and 50.0 plus or minus 4 sr at 532 nm and 1064 nm, respectively, using the T-Matrix calculations applied to measured size spectra. Finally, in situ measurements of the total scattering (550 nm) and absorption coefficients (532 nm) are used to generate an extinction profile that is used to constrain the CALIPSO 532 nm extinction profile.

  15. Spatial and Temporal Variability in Bottom Roughness: Implications to High Frequency Subcritical Penetration and Backscatter

    National Research Council Canada - National Science Library

    Williams, Kevin


    .... Since the sediment roughness evolves due to hydrodynamic and biological processes, concurrent, co-located measurement of roughness and acoustic penetration/backscattering is essential for testing...

  16. Time domain attenuation estimation method from ultrasonic backscattered signals. (United States)

    Ghoshal, Goutam; Oelze, Michael L


    Ultrasonic attenuation is important not only as a parameter for characterizing tissue but also for compensating other parameters that are used to classify tissues. Several techniques have been explored for estimating ultrasonic attenuation from backscattered signals. In the present study, a technique is developed to estimate the local ultrasonic attenuation coefficient by analyzing the time domain backscattered signal. The proposed method incorporates an objective function that combines the diffraction pattern of the source/receiver with the attenuation slope in an integral equation. The technique was assessed through simulations and validated through experiments with a tissue mimicking phantom and fresh rabbit liver samples. The attenuation values estimated using the proposed technique were compared with the attenuation estimated using insertion loss measurements. For a data block size of 15 pulse lengths axially and 15 beamwidths laterally, the mean attenuation estimates from the tissue mimicking phantoms were within 10% of the estimates using insertion loss measurements. With a data block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values estimated from the liver samples were within 10% of the attenuation values estimated from the insertion loss measurements.

  17. Rutherford backscatter measurements on tellurium and cadmium implanted gallium arsenide

    International Nuclear Information System (INIS)

    Bell, E.C.


    The primary aim of the work described in this thesis was to examine implanted layers of the dopant impurities cadmium and tellurium in gallium arsenide and to experimentally assess their potential for producing electrically active layers. 1.5 MeV Rutherford backscattering measurements of lattice disorder and atom site location have been used to assess post implantation thermal annealing and elevated temperature implantations to site the dopant impurities on either gallium or arsenic lattice positions in an otherwise undisordered lattice. Pyrolitically deposited silicon dioxide was used as an encapsulant to prevent thermal dissociation of the gallium arsenide during annealing. It has been shown that high doses of cadmium and tellurium can be implanted without forming amorphous lattice disorder by heating the gallium arsenide during implantation to relatively low temperatures. Atom site location measurements have shown that a large fraction of a tellurium dose implanted at 180 0 C is located on or near lattice sites. Channeled backscatter measurements have shown that there is residual disorder or lattice strain in gallium arsenide implanted at elevated temperatures. The extent of this disorder has been shown to depend on the implanted dose and implantation temperature. The channeling effect has been used to measure annealing of the disorder. (author)

  18. Data analysis of backscattering LIDAR system correlated with meteorological data

    International Nuclear Information System (INIS)

    Uehara, Sandro Toshio


    In these last years, we had an increase in the interest in the monitoring of the effect of the human activity being on the atmosphere and the climate in the planet. The remote sensing techniques has been used in many studies, also related the global changes. A backscattering LIDAR system, the first of this kind in Brazil, has been used to provide the vertical profile of the aerosol backscatter coefficient at 532 nm up to an altitude of 4-6 km above sea level. In this study, data has was collected in the year of 2005. These data had been correlated with data of solar photometer CIMEL and also with meteorological data. The main results had indicated to exist a standard in the behavior of these meteorological data and the vertical distribution of the extinction coefficient gotten through LIDAR. In favorable periods of atmospheric dispersion, that is, rise of the temperature of associated air the fall of relative humidity, increase of the atmospheric pressure and low ventilation tax, was possible to determine with good precision the height of the Planetary Boundary Layer, as much through the vertical profile of the extinction coefficient how much through the technique of the vertical profile of the potential temperature. The technique LIDAR showed to be an important tool in the determination of the thermodynamic structure of the atmosphere, assisting to characterize the evolution of the CLP throughout the day, which had its good space and secular resolution. (author)

  19. Middle East versus Saharan dust extinction-to-backscatter ratios

    Directory of Open Access Journals (Sweden)

    A. Nisantzi


    Full Text Available Four years (2010–2013 of observations with polarization lidar and sun/sky photometer at the combined European Aerosol Research Lidar Network (EARLINET and Aerosol Robotic Network (AERONET site of Limassol (34.7° N, 33° E, Cyprus, were used to compare extinction-to-backscatter ratios (lidar ratios for desert dust from Middle East deserts and the Sahara. In an earlier article, we analyzed one case only and found comparably low lidar ratios < 40 sr for Middle East dust. The complex data analysis scheme is presented. The quality of the retrieval is checked within a case study by comparing the results with respective Raman lidar solutions for particle backscatter, extinction, and lidar ratio. The applied combined lidar/photometer retrievals corroborate recent findings regarding the difference between Middle East and Saharan dust lidar ratios. We found values from 43–65 sr with a mean (±standard deviation of 53 ± 6 sr for Saharan dust and from 33–48 sr with a mean of 41 ± 4 sr for Middle East dust for the wavelength of 532 nm. The presented data analysis, however, also demonstrates the difficulties in identifying the optical properties of dust even during outbreak situations in the presence of complex aerosol mixtures of desert dust, marine particles, fire smoke, and anthropogenic haze.

  20. ILC beam energy measurement by means of laser Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Muchnoi, N. [Budker Inst. for Nuclear Physics, Novosibirsk (Russian Federation); Schreiber, H.J.; Viti, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)


    A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered {gamma}-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of 10{sup -4} or better on a bunch-to-bunch basis while the electron and positron beams are in collision. (orig.)

  1. Coherent backscattering in the soft x-ray region

    International Nuclear Information System (INIS)

    Matone, G.; Luccio, A.


    It is shown that coherent polarized soft x-rays can be produced by a combination of two techniques - stimulated amplification of laser light in a magnetic undulator, and Compton scattering of laser photons on an electron beam. In the combined technique, laser radiation is Compton scattered from a relativistic electron beam, whose current or charge density is periodically modulated. An electron beam and a laser beam propagate through an undulator along the same line. Inside the undulator, the laser electromagnetic waste produces a modulation of the electron energy. After some drift space, the modulation of the electron energy transforms into a modulation of the beam longitudinal charge density. The laser photons are reflected by a concave mirror against the electrons and are backscattered. In the process, their energy is greatly increased. If the electron and laser photon energy are matched properly, the modulated electron beam may act as a moving diffraction grating, and the backscattered x-rays show a high degree of coherence. The mechanism of modulation is described. The effects of electron beam energy spread, finite electron beam emittance, and undulator imperfections are discussed. The theory of scattering of a light wave by a bunched electron beam and the properties of the scattered radiation are examined

  2. Variation of backscatter as an indicator of boundary layer structure

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, M. [UMIST, Dept. of Chemical Engineering, Manchester (United Kingdom); Hunter, G.C. [National Power, Swindon (United Kingdom)


    In this work we have developed software to display cross-sections of the variance of backscatter over a given sampling period in addition to its absolute mean. We have analyzed a series of Lidar cross-sections of elevated plumes dispersing into a convective BL and have then derived profiles both of the mean backscatter, , as a function of height and of its relative, shot-to-shot, variation, {radical} /. The latter is a measure of the homogeneity of the aerosol. There is no cheap device for measuring BL depths so we were interested in comparing depths estimated using our Lidar with those predicted by the current ADMS atmospheric dispersion model. This is based on integrating an energy budget to predict the BL development and as such relies on values for the initial lapse rate and for the surface sensible heat flux. A major shortcoming of the model appears to be that, in the absence of measurements, it must assume a default value for the former; the latter may be estimated from surface measurements but is very sensitive to the assumed availability of surface moisture. (LN)

  3. Investigation of sheared liquids by neutron backscattering and reflectivity

    CERN Document Server

    Wolff, M; Hock, R; Frick, B; Zabel, H


    We have investigated by neutron scattering structural and dynamical properties of water solutions of the triblock copolymer P85 under shear. To this end a shear cell that suits the requirements for neutron backscattering and another for reflectivity experiments have been built. In reflectivity measurements we find the polymer concentration (nominal concentration of 33% by weight) to vary right at the surface between 12% and 52% for hydrophilic or hydrophobic coated silicon wavers, for temperatures between 18 C and 73 C and for shear rates up to 2500 s sup - sup 1. Additional structural changes deeper in the bulk are also observed. On the backscattering instrument (IN10 at ILL) we find that the liquid appears to stick to the plates of the shear cell, implying an unusual macroscopic velocity distribution that differs from that found earlier for lubrication oils. We report further on changes of the quasielastic line width in the direction of the shear gradient for different temperatures and shear rates. (orig.)

  4. Three-beam aerosol backscatter correlation lidar for wind profiling (United States)

    Prasad, Narasimha S.; Radhakrishnan Mylapore, Anand


    The development of a three-beam aerosol backscatter correlation (ABC) light detection and ranging (lidar) to measure wind characteristics for wake vortex and plume tracking applications is discussed. This is a direct detection elastic lidar that uses three laser transceivers, operating at 1030-nm wavelength with ˜10-kHz pulse repetition frequency and nanosec class pulse widths, to directly obtain three components of wind velocities. By tracking the motion of aerosol structures along and between three near-parallel laser beams, three-component wind speed profiles along the field-of-view of laser beams are obtained. With three 8-in. transceiver modules, placed in a near-parallel configuration on a two-axis pan-tilt scanner, the lidar measures wind speeds up to 2 km away. Optical flow algorithms have been adapted to obtain the movement of aerosol structures between the beams. Aerosol density fluctuations are cross-correlated between successive scans to obtain the displacements of the aerosol features along the three axes. Using the range resolved elastic backscatter data from each laser beam, which is scanned over the volume of interest, a three-dimensional map of aerosol density can be generated in a short time span. The performance of the ABC wind lidar prototype, validated using sonic anemometer measurements, is discussed.

  5. Optical transmission of glass for the National Ignition Facility near backscatter imagers under x-ray exposurea) (United States)

    London, R. A.; Froula, D. H.; Sorce, C. M.; Moody, J. D.; Suter, L. J.; Glenzer, S. H.; Jones, O. S.; Meezan, N. B.; Rosen, M. D.


    In experiments at the National Ignition Facility (NIF), the near backscatter imager materials need to maintain high optical transmission while exposed to hohlraum generated x rays. Glass plates are incorporated in the design to protect the optical scattering plates from x-ray damage. Radiation environments spanning those expected on NIF have been produced at the Omega Laser Facility by symmetric laser illumination of 1mm sized gold spheres. The time-dependent ultraviolet transmission of sample glass plates was measured. The data are interpreted with a free electron absorption model. Combined with the simulations of the hohlraum x-ray emission, this model is used to predict the transmission of the glass plates on the NIF. We predict that the plates should perform adequately up to the peak of the laser pulse.

  6. Nutrition and magnesium absorption


    Brink, E.J.


    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium absorption was neither affected by soybean protein in the diet nor by supplemental phytate. The inhibitory influence of soybean protein and phytate on apparent magnesium absorption was found ...

  7. Absorption and excretion tests

    International Nuclear Information System (INIS)

    Berberich, R.


    The absorption and excretion of radiopharmaceuticals is still of interest in diagnostic investigations of nuclear medicine. In this paper the most common methods of measuring absorption and excretion are described. The performance of the different tests and their standard values are discussed. More over the basic possibilities of measuring absorption and excretion including the needed measurement equipments are presented. (orig.) [de

  8. Backscattered electron imaging and electron backscattered diffraction in the study of bacterial attachment to titanium alloy structure. (United States)

    Wang, Anqi; Jones, Ian P; Landini, Gabriel; Mei, Junfa; Tse, Yau Y; Li, Yue X; Ke, Linnan; Huang, Yuanli; Liu, L I; Wang, Chunren; Sammons, Rachel L


    The application of secondary electron (SE) imaging, backscattered electron imaging (BSE) and electron backscattered diffraction (EBSD) was investigated in this work to study the bacterial adhesion and proliferation on a commercially pure titanium (cp Ti) and a Ti6Al4V alloy (Ti 64) with respect to substrate microstructure and chemical composition. Adherence of Gram-positive Staphylococcus epidermidis 11047 and Streptococcus sanguinis GW2, and Gram-negative Serratia sp. NCIMB 40259 and Escherichia coli 10418 was compared on cp Ti, Ti 64, pure aluminium (Al) and vanadium (V). The substrate microstructure and the bacterial distribution on these metals were characterised using SE, BSE and EBSD imaging. It was observed that titanium alloy-phase structure, grain boundaries and grain orientation did not influence bacterial adherence or proliferation at microscale. Adherence of all four strains was similar on cp Ti and Ti 64 surfaces whilst inhibited on pure Al. This work establishes a nondestructive and straight-forward statistical method to analyse the relationship between microbial distribution and metal alloy structure. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  9. Characterizing Three-Dimensional Mixing Process in a River Confluence using Hydro-acoustical Backscatter and Flow Measurement (United States)

    Son, Geunsoo; Kim, Dongsu; Kim, YoungDo; Lyu, Siwan; Kim, Seojun


    concentration by using acoustic backscatter. Cross-sectional ADCP measurements in a confluence were collected with high spatial resolution in order to analyze the details of spatial distribution in the perspective of the three-dimensional mixing patterns of flow and sediment, where backscatters (or SNR) measured from ADCPs were used to track sediment mixing assuming that it could be a surrogate to estimate the suspended sediment concentration. Raw backscatter data were corrected by considering the beam spreading and absorption by water. Also, an optical Laser diffraction instrument (LISST) was used to verify the method of acoustic backscatter and to collect the particle size distribution of main stream and tributary. In addition, image-based spatial distributions of sediment mixture in the confluence were monitored in various flow conditions by using an unmanned aerial vehicle (UAV), which were compared with the spatial distribution of acoustic backscatter. As results, we found that when acoustic backscatter and flow measurements by ADCPs were well processed, they could be proper indicators to identify the spatial patterns of the three-dimensional mixing process between two rivers.

  10. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Recker, R.R.


    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  11. Combining angular response classification and backscatter imagery segmentation for benthic biological habitat mapping (United States)

    Che Hasan, Rozaimi; Ierodiaconou, Daniel; Laurenson, Laurie


    Backscatter information from multibeam echosounders (MBES) have been shown to contain useful information for the characterisation of benthic habitats. Compared to backscatter imagery, angular response of backscatter has shown advantages for feature discrimination. However its low spatial resolution inhibits the generation of fine scale habitat maps. In this study, angular backscatter response was combined with image segmentation of backscatter imagery to characterise benthic biological habitats in Discovery Bay Marine National Park, Victoria, Australia. Angular response of backscatter data from a Reson Seabat 8101 MBES (240 kHz) was integrated with georeferenced underwater video observations for constructing training data. To produce benthic habitat maps, decision tree supervised classification results were combined with mean shift image segmentation for class assignment. The results from mean angular response characteristics show effects of incidence angle at the outer angle for invertebrates (INV) and mixed red and invertebrates (MRI) classes, whilst mixed brown algae (MB) and mixed brown algae and invertebrates (MBI) showed similar responses independent from incidence angle. Automatic segmentation processing produce over segmented results but showed good discrimination between heterogeneous regions. Accuracy assessment from habitat maps produced overall accuracies of 79.6% (Kappa coefficient = 0.66) and 80.2% (Kappa coefficient = 0.67) for biota and substratum classifications respectively. MRI and MBI produced the lowest average accuracy while INV the highest. The ability to combine angular response and backscatter imagery provides an alternative approach for investigating biological information from acoustic backscatter data.

  12. Using multi-beam echo sounder backscatter data for sediment classification in very shallow water environments

    NARCIS (Netherlands)

    Amiri-Simkooei, A.R.; Snellen, M.; Simons, D.G.


    In a recent work described in Ref. [1], an angle-independent methodology was developed to use the multi-beam echo sounder backscatter (MBES) data for the seabed sediment classification. The method employs the backscatter data at a certain angle to obtain the number of sediment classes and to

  13. Application of Electron Backscatter Diffraction to Phase Identification

    Energy Technology Data Exchange (ETDEWEB)

    El-Dasher, B S; Deal, A


    The identification of crystalline phases in solids requires knowledge of two microstructural properties: crystallographic structure and chemical composition. Traditionally, this has been accomplished using X-ray diffraction techniques where the measured crystallographic information, in combination with separate chemical composition measurements for specimens of unknown pedigrees, is used to deduce the unknown phases. With the latest microstructural analysis tools for scanning electron microscopes, both the crystallography and composition can be determined in a single analysis utilizing electron backscatter diffraction and energy dispersive spectroscopy, respectively. In this chapter, we discuss the approach required to perform these experiments, elucidate the benefits and limitations of this technique, and detail via case studies how composition, crystallography, and diffraction contrast can be used as phase discriminators.

  14. Coherent Backscattering from Regolith-type Particulate Samples (United States)

    Kaasalainen, S.; Piironen, J.; Muinonen, K.; Kartunen, H.; Peltoniemi, J.


    Laboratory study is important in the photometric study of asteroids and planetary surfaces, since it gives an opportunity for systematic variation and comparison of samples. We present photometric measurements at phase angles from zero to 18 degrees for particulate and solid samples. Results are shown for aluminium oxide powder, Sahara sand and different meteorite rocks. The experimental setup consists of a laser light source, and a beam splitter for reaching the smallest phase angles. The device is also designed for outdoor use, allowing for the first time the systematic phase curve study of terrestrial snow and ices. Measurements at excact zero phase are especially important in the further study and understanding of the role of the coherent backscattering in the opposition effect of the solar system satellites and asteroids, including bright and icy objects. The results will also be applied in the interpretation of, e.g., the SMART-1 AMIE data.

  15. Automated determination of crystal orientations from electron backscattering patterns

    DEFF Research Database (Denmark)

    Lassen, Niels Christian Krieger


    these calibration parameters can be estimated with high precision. The quality of EBSPs provides important information about the reliability of the measured crystal orientations and about the perfection of the lattice in which the pattern is generated. A measure which allows the quality of EBSPs to be evaluated......The electron backscattering pattern (EBSP) technique is widely accepted as being an extremely powerful tool for measuring the crystallographic orientation of individual crystallites in polycrystalline materials. Procedures which allow crystal orientations to be calculated on the bases...... of a pattern recognition procedure which enables 8 to 12 bands to be localized in typical EBSPs from a modern system. It will be described, how these automatically localized bands can be indexed and used for optimal estimation of the unknown crystal orientations. A necessary prerequisite for precise...

  16. Use of Rutherford Backscattering to determine uranium deposit uniformity

    International Nuclear Information System (INIS)

    Wasson, O.A.; Schrack, R.A.


    A Rutherford Backscattering (RBS) facility has been established at the 3-MV positive-ion accelerator at the National Bureau of Standards. This facility has been used to study the areal density distribution of uranium deposits used in neutron cross section measurements. A versatile scattering chamber with numerous ports, five-axis goniometer, target ladder, and solid state detector is in operation. Beams of 1 MeV He + ions and 5 MeV He ++ ions are available. The variation in areal density of a 75 cm diameter UO 2 deposit was measured using a 1 MeV He + beam. The results are in excellent agreement with those obtained from alpha-particle activity measurements. However, the RBS measurements provide better definition of the uniformity near the edge of the deposits. Our experience in the use of these two methods to characterize the areal densities of deposits for cross section measurements will be presented. (author). Abstract only

  17. Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography. (United States)

    Rice, Katherine P; Chen, Yimeng; Prosa, Ty J; Larson, David J


    There are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.

  18. Electron backscatter diffraction: Strategies for reliable data acquisition and processing

    International Nuclear Information System (INIS)

    Randle, Valerie


    In electron backscatter diffraction (EBSD) software packages there are many user choices both in data acquisition and in data processing and display. In order to extract maximum scientific value from an inquiry, it is helpful to have some guidelines for best practice in conducting an EBSD investigation. The purpose of this article therefore is to address selected topics of EBSD practice, in a tutorial manner. The topics covered are a brief summary on the principles of EBSD, specimen preparation, calibration of an EBSD system, experiment design, speed of data acquisition, data clean-up, microstructure characterisation (including grain size) and grain boundary characterisation. This list is not meant to cover exhaustively all areas where EBSD is used, but rather to provide a resource consisting of some useful strategies for novice EBSD users.

  19. Back-scatter based whispering gallery mode sensing (United States)

    Knittel, Joachim; Swaim, Jon D.; McAuslan, David L.; Brawley, George A.; Bowen, Warwick P.


    Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive real-time observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors. PMID:24131939

  20. Using Rutherford Backscattering Spectroscopy to Characterize Targets for MTW (United States)

    Brown, Gunnar; Stockler, Barak; Ward, Ryan; Freeman, Charlie; Padalino, Stephen; Stillman, Collin; Ivancic, Steven; Reagan, S. P.; Sangster, T. C.


    A study is underway to determine the composition and thickness of targets used at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) using Rutherford backscattering spectroscopy (RBS). In RBS, an ion beam is incident on a sample and the scattered ions are detected with a surface barrier detector. The resulting energy spectra of the scattered ions can be analyzed to determine important parameters of the target including elemental composition and thickness. Proton, helium and deuterium beams from the 1.7 MV Pelletron accelerator at SUNY Geneseo have been used to characterize several different targets for MTW, including CH and aluminum foils of varying thickness. RBS spectra were also obtained for a cylindrical iron buried-layer target with aluminum dopant which was mounted on a silicon carbide stalk. The computer program SIMNRA is used to analyze the spectra. This work was funded in part by a Grant from the DOE through the Laboratory for Laser Energetics.

  1. Simulation of multiple scattering background in heavy ion backscattering spectrometry

    International Nuclear Information System (INIS)

    Li, M.M.; O'Connor, D.J.


    With the development of heavy ion backscattering spectrometry (HIBS) for the detection of trace quantities of heavy-atom impurities on Si surfaces, it is necessary to quantify the multiple scattering contribution to the spectral background. In the present work, the Monte Carlo computer simulation program TRIM has been used to study the backscattering spectrum and the multiple scattering background features for heavy ions C, Ne, Si, Ar and Kr impinging on four types of targets: (1) a single ultra-thin (free standing) Au film of 10 A thickness, (2) a 10 A Au film on a 50 A Si surface, (3) a 10 A Au film on an Si substrate (10 000 A), and (4) a thick target (10 000 A) of pure Si. The ratio of the signal from the Au thin layer to the background due to multiple scattering has been derived by fitting the simulation results. From the simulation results, it is found that the Au film contributes to the background which the Si plays a role in developing due to the ion's multiple scattering in the substrate. Such a background is generated neither by only the Au thin layer nor by the pure Si substrate independently. The corresponding mechanism of multiple scattering in the target can be explained as one large-angle scattering in the Au layer and subsequently several small angle scatterings in the substrate. This study allows an appropriate choice of incident beam species and energy range when the HIBS is utilized to analyse low level impurities in Si wafers


    Directory of Open Access Journals (Sweden)

    L. Shi


    Full Text Available The Polarimetric and Interferometric Synthetic Aperture Radar (POLINSAR is widely used in urban area nowadays. Because of the physical and geometric sensitivity, the POLINSAR is suitable for the city classification, power-lines detection, building extraction, etc. As the new X-band POLINSAR radar, the china prototype airborne system, XSAR works with high spatial resolution in azimuth (0.1 m and slant range (0.4 m. In land applications, SAR image classification is a useful tool to distinguish the interesting area and obtain the target information. The bare soil, the cement road, the water and the building shadow are common scenes in the urban area. As it always exists low backscattering sign objects (LBO with the similar scattering mechanism (all odd bounce except for shadow in the XSAR images, classes are usually confused in Wishart-H-Alpha and Freeman-Durden methods. It is very hard to distinguish those targets only using the general information. To overcome the shortage, this paper explores an improved algorithm for LBO refined classification based on the Pre-Classification in urban areas. Firstly, the Pre-Classification is applied in the polarimetric datum and the mixture class is marked which contains LBO. Then, the polarimetric covariance matrix C3 is re-estimated on the Pre-Classification results to get more reliable results. Finally, the occurrence space which combining the entropy and the phase-diff standard deviation between HH and VV channel is used to refine the Pre-Classification results. The XSAR airborne experiments show the improved method is potential to distinguish the mixture classes in the low backscattering objects.

  3. [Obtaining aerosol backscattering coefficient using pure rotational Raman-Mie scattering spectrum]. (United States)

    Rong, Wei; Chen, Si-Ying; Zhang, Yin-Chao; Chen, He; Guo, Pan


    Both the traditional Klett and Fernald methods used to obtain atmospheric aerosol backscattering coefficient require the hypothesis of relationship between the extinction coefficient and backscattering coefficient, and this will bring error. According to the theory that the pure rotational Raman backscattering coefficient is only related to atmospheric temperature and pressure, a new method is presented for inverting aerosol backscattering coefficient, which needed the intensity of elastic scattering and rotational Raman combined with atmospheric temperature and pressure obtained with the sounding balloons in this article. This method can not only eliminate the errors of the traditional Klett and Fernald methods caused by the hypothesis, but also avoid the error caused by the correction of the overlap. Finally, the aerosol backscattering coefficient was acquired by using this method and the data obtained via the Raman-Mie scattering Lidar of our lab. And the result was compared with that of Klett and Fernald.

  4. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry]. (United States)

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng


    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  5. TU-E-BRA-02: A Method to Remove Support Arm Backscatter from EPID Images. (United States)

    King, B; Greer, P


    To develop a method for removing the effect of support arm backscatter from Varian electronic portal imaging devices (EPIDs), improving the dosimetric abilities of the imager. A physical, kernel based model of the backscatter signal produced during an exposure was developed. The model parameters were determined through an optimization process, comparing measured images without arm backscatter (EPID removed from arm) to measured images that include arm backscatter. The backscatter model was used to develop a backscatter correction process that removes the support arm backscatter from measured EPID images. The correction process was tested by applying the method to measured images of 17 rectangular asymmetric fields and comparing the Result to off-arm images. The same process was repeated with 42 IMRT fields. The backscatter removal process was able to effectively remove the arm backscatter from all of the measured images and accurately predict the measured off-arm images. Comparing the corrected images to the measured off-arm images, the mean absolute difference at the centre of each rectangular field was 0.29% (standard deviation 0.18%). This is an improvement over the uncorrected images which gave a mean difference of 1.01% (standard deviation 0.73%). The largest discrepancy observed with the corrected images was 0.6%, compared to 2.8% for the uncorrected images. Comparing the corrected IMRT images to the measured off-arm images, an overall mean gamma value of 0.28 (standard deviation 0.04) was found using 2%, 2mm criteria. Comparison of the uncorrected images to the measured off-arm images resulted in an overall mean gamma of 0.40 (standard deviation 0.10). A method for accurately and reliably removing the effect of support arm backscatter from EPID images has been developed and extensively tested. The method can be applied to any measured EPID image and does not require any additional information about the exposure. © 2012 American Association of Physicists in

  6. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand


    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  7. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  8. Seafloor classification of the mound and channel provinces of the Porcupine Seabight: An application of the multibeam angular backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Beyer, A.; Chakraborty, B.; Schenke, H.W.

    provinces like: carbonate mounds, buried mounds, seafloor channels, and inter-channel areas. A detailed methodology is developed to produce a map of angle-invariant (normalized) backscatter data by correcting the local angular backscatter values. The present...

  9. Absorption heat pumps

    International Nuclear Information System (INIS)

    Formigoni, C.


    A brief description of the difference between a compression and an absorption heat pump is made, and the reasons why absorption systems have spread lately are given. Studies and projects recently started in the field of absorption heat pumps, as well as criteria usually followed in project development are described. An outline (performance targets, basic components) of a project on a water/air absorption heat pump, running on natural gas or LPG, is given. The project was developed by the Robur Group as an evolution of a water absorption refrigerator operating with a water/ammonia solution, which has been on the market for a long time and recently innovated. Finally, a list of the main energy and cost advantages deriving from the use of absorption heat pumps is made [it

  10. High-spectral-resolution lidar using an iodine absorption filter for atmospheric measurements (United States)

    Liu, Zhaoyan; Matsui, Ichiro; Sugimoto, Nubuo


    We develop high-spectral-resolution lidar (HSRL) using an iodine absorption filter and a narrow-band Nd:YAG laser with high-frequency-doubled output and use it for atmospheric measurements at the National Institute for Environmental Studies. The lidar system separates Doppler-broadened molecular scattering and unbroadened aerosol scattering components of the backscattered laser light, consequently providing direct measurements of these two signals. Due to stable and strong absorption at room temperature, iodine absorption filters are easy to use and they enable high rejection against aerosol scattering with a short length. The measurement principle with an error analysis and the system construction of the HSRL are described. Examples of aerosol and cloud observations made by the HSRL are also presented. The experimental results indicate that the HSRL is a powerful tool for quantitatively measuring aerosol and cloud optical properties. The use of a high-output laser gives our system the ability to provide stratospheric observations. We also present the HSRL measurements of the stratospheric temperature and backscatter profiles with better resolutions in both range and time. An example of temperature and backscatter measurements is shown for the altitude range from approximately 10 to approximately 40 km with a vertical resolution of 300 m and an integrated time of approximately 2 h.

  11. Impact of diurnal variation in vegetation water content on radar backscatter of maize during water stress (United States)

    van Emmerik, Tim; Steele-Dunne, Susan; Judge, Jasmeet; van de Giesen, Nick


    Microwave emission and backscatter of vegetated surfaces are influenced by vegetation water content (VWC), which varies in response to availability of soil moisture in the root zone. Understanding the influence of diurnal VWC dynamics on radar backscatter will improve soil moisture retrievals using microwave remote sensing, and will provide insight into the potential use for radar to directly monitor vegetation water status. The goal of this research is to investigate the effect of diurnal variation in VWC of an agricultural canopy on backscatter for different radar configurations. Water stress was induced in a corn (Zea mays) canopy near Citra, Florida, between September 1 and October 20, 2013. Diurnal destructive samples from the canopy were collected to determine leaf, stalk and total VWC. Water stress was quantified by calculating the evaporation deficit and measuring the soil water tension. The water-cloud model was used to model the influence of VWC and soil moisture variations on backscatter for a range of frequencies, polarizations and incidence angles. Furthermore, radar backscatter time series was simulated to show the effect of water stress on the diurnal variation in backscatter due to VWC. Results of this study show the very significant effects that VWC dynamics have on radar backscatter. We also highlight the potential for vegetation and soil water status monitoring using microwave remote sensing.

  12. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan


    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  13. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  14. Relationship of Light Scattering at an Angle in the Backward Direction to the Backscattering Coefficient (United States)

    Boss, Emmanuel; Pegau, W. Scott


    We revisit the problem of computing the backscattering coefficient based on the measurement of scattering at one angle in the back direction. Our approach uses theory and new observations of the volume scattering function (VSF) to evaluate the choice of angle used to estimate bb . We add to previous studies by explicitly treating the molecular backscattering of water (bbw ) and its contribution to the VSF shape and to bb . We find that there are two reasons for the tight correlation between observed scattering near 120 and the backscattering coefficient reported by Oishi [Appl. Opt. 29, 4658, (1990) , namely, that (1) the shape] of the VSF of particles (normalized to the backscattering) does not vary much near that angle for particle assemblages of differing optical properties and size, and (2) the ratio of the VSF to the backscattering is not sensitive to the contribution by water near this angle. We provide a method to correct for the water contribution to backscattering when single-angle measurements are used in the back direction (for angles spanning from near 90 to 160 ) that should provide improved estimates of the backscattering coefficient.

  15. Gas-Filled Targets to Study Laser Backscatter on the National Ignition Facility (United States)

    London, R. A.; Williams, E. A.; Hinkel, D. E.; Moody, J. D.; Suter, L. J.


    To achieve indirect drive fusion at the National Ignition Facility (NIF), laser beams must propagate through several millimeters of high-density plasma to reach the hohlraum walls. Stimulated Brillouin and Raman backscatter could create problems with energetics and/or symmetry. Laser backscatter at NIF will be diagnosed with full aperture backscatter systems (FABS) and near backscatter imagers (NBI). Several gas-filled targets (``gas pipes'') have been designed to provide backscatter sources to commission the diagnostics. The 7-mm long gas pipes are filled with various gases, including C5H12 and CO2, and are irradiated by a NIF quad with 16 kJ of energy in 2-4 ns pulses. We describe the design of the gas pipes using hydrodynamics and laser-plasma-interaction computer codes. The relationship between the design parameters (gas composition and density and laser pulse shape) and the character of the backscatter (Brillouin versus Raman and narrow versus broad angle) are discussed. Comparisons of predicted and measured backscatter distributions and levels are discussed.

  16. Characterization of Particle Backscattering of Global Highly Turbid Waters From VIIRS Ocean Color Observations (United States)

    Shi, Wei; Wang, Menghua


    Normalized water-leaving radiance spectra nLw(λ) at the near-infrared (NIR) from five years of observations (2012-2016) with the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) are used to derive the particle backscattering coefficients bbp(λ) for global highly turbid coastal and inland waters. Based on the fact that the absorption coefficient of sea water aw(λ) is generally much larger than those of the other constituents aiop(λ) at the NIR wavelengths in coastal and inland waters, an NIR-based bbp(λ) algorithm for turbid coastal and inland waters has been developed and used in this study. This algorithm can be safely used for highly turbid waters with nLw(745) and nLw(862) Amazon River Estuary, the La Plata River Estuary, the Meghna River Estuary, the Atchafalaya River Estuary, and Lake Taihu are characterized and quantified. The coefficient bbp(λ) can reach over ˜3-4 m-1 in the Amazon River Estuary and China's east coastal region. The Amazon River Estuary is identified as the most turbid region in the global ocean in terms of bbp(λ) magnitude. bbp(λ) spectra in these five highly turbid regions are also seasonal-dependent and regional-dependent. In the highly turbid waters of China's east coastal region and the Amazon River Estuary, bbp(λ) generally increases in wavelength from 410 to 862 nm, while it decreases in the La Plata River Estuary and Atchafalaya River Estuary. This is attributed to the different particle size distributions in these waters. The geophysical implication of the bbp(λ) spectral curvatures for different waters is discussed. To improve global bbp(λ) for both open oceans and coastal turbid waters, a new combined NIR-based and Quasi-Analytical Algorithm (QAA)-based bbp(λ) algorithm is proposed and demonstrated.

  17. Sub-meter sediment classification using 400 kHz multibeam acoustic backscatter (United States)

    Buscombe, D.; Grams, P. E.


    Bathymetric mapping in shallow water (up to a few hundred m water depth) involves high frequency (> 100 kHz) swath sonar which sound at high spatial resolution (beam footprints up to a few m). Most acoustical sediment classification methods proposed to date either 1) utilize only a subset of backscatter information or 2) require a substantial amount of spatial averaging. For example, the angular dependence in backscatter often means that only backscatter from one or a subset of beam angles is used for classification. Backscatter is inherently variable in shallow water, owing to small numbers of independent scatterers within beam footprints, leading to non-stationarity. These factors have imposed limits on spatial resolutions of sediment classifications (typically up to 10s of m grid sizes). However, there are situations where finer resolution is required. We detail a new empirical spatially continuous sediment classification method that very reliably distinguishes between clastic substrates (sand, gravel, rocks/boulders, and clastic mixtures) in shallow water (so far, tested up to 30m) with a 400 kHz (Reson 7125) multibeam sonar, down to sub-m grid scales. The advance relies on 1) computing backscatter strength from long-echo amplitudes recorded by a multibeam sonar, in a way that maximizes the amount of usable data, accounting for directivity and bed slope effects and 2) utilizing the spatial autocorrelation in backscatter to maximize the number of observations upon which the classification is based. We 1) present a form of the active sonar equation that expresses instantaneous backscattering strength as a function of interfacial target strength and beam footprint based on modeled sonar geometry; 2) report on backscatter strengths over known sediment types (determined from underwater video observations); and 3) present the classification method which uses a calibrated machine-learning approach on the substrate-specific spectral content of backscatter strengths.

  18. Solar absorption surface panel (United States)

    Santala, Teuvo J.


    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  19. Nutrition and magnesium absorption

    NARCIS (Netherlands)

    Brink, E.J.


    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true

  20. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Loos-Vollebregt, M.T.C. de.


    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  1. Quantitative evaluating the energy field of pulsed x radiation backscattered in air

    International Nuclear Information System (INIS)

    Kosarev, V.D; Mukhin, V.P.


    Air background (fraction of radiation, backscattered in air) taken into account when conducting measurements using the devices with operating principle based on the dependence of backscattered γ-quanta flux density reo.istered in the given time interval (strobe) on the measured parameters is evaluated. It is shown that the energy of γ-quanta backscattered in an air layer energy of pulsed x radiation background in a strobe is defined not only by initial radiation energy and collimation angle but by the strobe location on time axis in relation to the radiated pulse as well i.e. by air layer location in space

  2. A multislice theory of electron scattering in crystals including backscattering and inelastic effects. (United States)

    Spiegelberg, Jakob; Rusz, Ján


    In the framework of the slice transition operator technique, a general multislice theory for electron scattering in crystals is developed. To achieve this generalization, we combine the approaches for inelastic scattering derived by Yoshioka [J. Phys. Soc. Jpn. 12, 6 (1957)] and backscattering based on the formalism of Chen and Van Dyck [Ultramicroscopy 70, 29-44 (1997)]. A computational realization of the obtained equations is suggested. The proposed computational scheme is tested on elastic backscattering of electrons, where we consider single backscattering in analogy to the computational scheme proposed by Chen and Van Dyck. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Diffuse optical microscopy for quantification of depth-dependent epithelial backscattering in the cervix (United States)

    Bodenschatz, Nico; Lam, Sylvia; Carraro, Anita; Korbelik, Jagoda; Miller, Dianne M.; McAlpine, Jessica N.; Lee, Marette; Kienle, Alwin; MacAulay, Calum


    A fiber optic imaging approach is presented using structured illumination for quantification of almost pure epithelial backscattering. We employ multiple spatially modulated projection patterns and camera-based reflectance capture to image depth-dependent epithelial scattering. The potential diagnostic value of our approach is investigated on cervical ex vivo tissue specimens. Our study indicates a strong backscattering increase in the upper part of the cervical epithelium caused by dysplastic microstructural changes. Quantization of relative depth-dependent backscattering is confirmed as a potentially useful diagnostic feature for detection of precancerous lesions in cervical squamous epithelium.

  4. A Dictionary Approach to Electron Backscatter Diffraction Indexing. (United States)

    Chen, Yu H; Park, Se Un; Wei, Dennis; Newstadt, Greg; Jackson, Michael A; Simmons, Jeff P; De Graef, Marc; Hero, Alfred O


    We propose a framework for indexing of grain and subgrain structures in electron backscatter diffraction patterns of polycrystalline materials. We discretize the domain of a dynamical forward model onto a dense grid of orientations, producing a dictionary of patterns. For each measured pattern, we identify the most similar patterns in the dictionary, and identify boundaries, detect anomalies, and index crystal orientations. The statistical distribution of these closest matches is used in an unsupervised binary decision tree (DT) classifier to identify grain boundaries and anomalous regions. The DT classifies a pattern as an anomaly if it has an abnormally low similarity to any pattern in the dictionary. It classifies a pixel as being near a grain boundary if the highly ranked patterns in the dictionary differ significantly over the pixel's neighborhood. Indexing is accomplished by computing the mean orientation of the closest matches to each pattern. The mean orientation is estimated using a maximum likelihood approach that models the orientation distribution as a mixture of Von Mises-Fisher distributions over the quaternionic three sphere. The proposed dictionary matching approach permits segmentation, anomaly detection, and indexing to be performed in a unified manner with the additional benefit of uncertainty quantification.

  5. Estimating the breast surface using UWB microwave monostatic backscatter measurements. (United States)

    Winters, David W; Shea, Jacob D; Madsen, Ernest L; Frank, Gary R; Van Veen, Barry D; Hagness, Susan C


    This paper presents an algorithm for estimating the location of the breast surface from scattered ultrawideband (UWB) microwave signals recorded across an antenna array. Knowing the location of the breast surface can improve imaging performance if incorporated as a priori information into recently proposed microwave imaging algorithms. These techniques transmit low-power microwaves into the breast using an antenna array, which in turn measures the scattered microwave signals for the purpose of detecting anomalies or changes in the dielectric properties of breast tissue. Our proposed surface identification algorithm consists of three procedures, the first of which estimates M points on the breast surface given M channels of measured microwave backscatter data. The second procedure applies interpolation and extrapolation to these M points to generate N > M points that are approximately uniformly distributed over the breast surface, while the third procedure uses these N points to generate a 3-D estimated breast surface. Numerical as well as experimental tests indicate that the maximum absolute error in the estimated surface generated by the algorithm is on the order of several millimeters. An error analysis conducted for a basic microwave radar imaging algorithm (least-squares narrowband beamforming) indicates that this level of error is acceptable. A key advantage of the algorithm is that it uses the same measured signals that are used for UWB microwave imaging, thereby minimizing patient scan time and avoiding the need for additional hardware.

  6. A fluctuation relation for the probability of energy backscatter (United States)

    Vela-Martin, Alberto; Jimenez, Javier


    We simulate the large scales of an inviscid turbulent flow in a triply periodic box using a dynamic Smagorinsky model for the sub-grid stresses. The flow, which is forced to constant kinetic energy, is fully reversible and can develop a sustained inverse energy cascade. However, due to the large number of degrees freedom, the probability of spontaneous mean inverse energy flux is negligible. In order to quantify the probability of inverse energy cascades, we test a local fluctuation relation of the form log P(A) = - c(V , t) A , where P(A) = p(| Cs|V,t = A) / p(| Cs|V , t = - A) , p is probability, and | Cs|V,t is the average of the least-squared dynamic model coefficient over volume V and time t. This is confirmed when Cs is averaged over sufficiently large domains and long times, and c is found to depend linearly on V and t. In the limit in which V 1 / 3 is of the order of the integral scale and t is of the order of the eddy-turnover time, we recover a global fluctuation relation that predicts a negligible probability of a sustained inverse energy cascade. For smaller V and t, the local fluctuation relation provides useful predictions on the occurrence of local energy backscatter. Funded by the ERC COTURB project.

  7. Measurements of the energy spectrum of backscattered fast neutrons

    International Nuclear Information System (INIS)

    Segal, Y.


    Experimental measurements have been made of the energy spectra of neutrons transmitted through slabs of iron, lead and perspex for incident neutron energies of 0.5, 1.0, 1.5 and 1.8 MeV. The neutron energy measurements were made using a He-3 spectrometer. The dependence of the neutrons energy spectrum as a function of scattering thickness was determined. The neutrons source used was a 3MeV Van de Graaff accelerator with a tritium target using the H 3 (p,n) He 3 reaction. The results obtained by the investigator on energy dependence of transmitted neutrons as a function of thickness of scattering material were compared, where possible, with the results obtained by other workers. The comparisons indicated good agreement. The experiment's results are compared with MORSE Monte Carlo calculated values. It is worthwhile to note that direct comparison between measured cross section values and the recommended ones are very far from satisfactory. In almost all cases the calculated spectrum is harder than the experimental one, a situation common to the penetrating and the back-scattered flux

  8. Orientation effects on indexing of electron backscatter diffraction patterns

    International Nuclear Information System (INIS)

    Nowell, Matthew M.; Wright, Stuart I.


    Automated Electron Backscatter Diffraction (EBSD) has become a well-accepted technique for characterizing the crystallographic orientation aspects of polycrystalline microstructures. At the advent of this technique, it was observed that patterns obtained from grains in certain crystallographic orientations were more difficult for the automated indexing algorithms to accurately identify than patterns from other orientations. The origin of this problem is often similarities between the EBSD pattern of the correct orientation and patterns from other orientations or phases. While practical solutions have been found and implemented, the identification of these problem orientations generally occurs only after running an automated scan, as problem orientations are often readily apparent in the resulting orientation maps. However, such an approach only finds those problem orientations that are present in the scan area. It would be advantageous to identify all regions of orientation space that may present problems for automated indexing prior to initiating an automated scan, and to minimize this space through the optimization of acquisition and indexing parameters. This work presents new methods for identifying regions in orientation space where the reliability of the automated indexing is suspect prior to performing a scan. This methodology is used to characterize the impact of various parameters on the indexing algorithm

  9. Compton-backscattered annihilation radiation from the Galactic Center region (United States)

    Smith, D. M.; Lin, R. P.; Feffer, P.; Slassi, S.; Hurley, K.; Matteson, J.; Bowman, H. B.; Pelling, R. M.; Briggs, M.; Gruber, D.


    On 1989 May 22, the High Energy X-ray and Gamma-ray Observatory for Nuclear Emissions, a balloon-borne high-resolution germanium spectrometer with an 18-deg FOV, observed the Galactic Center (GC) from 25 to 2500 keV. The GC photon spectrum is obtained from the count spectrum by a model-independent method which accounts for the effects of passive material in the instrument and scattering in the atmosphere. Besides a positron annihilation line with a flux of (10.0 +/- 2.4) x 10 exp -4 photons/sq cm s and a full width at half-maximum (FWHM) of (2.9 + 1.0, -1.1) keV, the spectrum shows a peak centered at (163.7 +/- 3.4) keV with a flux of (1.55 +/- 0.47) x 10 exp -3 photons/sq cm s and a FWHM of (24.4 +/- 9.2) keV. The energy range 450-507 keV shows no positronium continuum associated with the annihilation line, with a 2-sigma upper limit of 0.90 on the positronium fraction. The 164 keV feature is interpreted as Compton backscatter of broadened and redshifted annihilation radiation, possibly from the source 1E 1740.7-2942.

  10. GLAS/ICESat L1B Global Backscatter Data V033 (United States)

    National Aeronautics and Space Administration — The product includes full 532 nm and 1064 nm calibrated attenuated backscatter profiles at 5 times per second, and from 10 to -1 km, at 40 times per second. Also the...

  11. Pseudo sidescan images from backscatter amplitude data of the Hydrosweep multibean sonar system

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.; Hagen, R.; Schenke, H.W.

    Using the rms (root mean square) backscatter amplitude values, a procedure was evolved to generate pseudo sidescan images. A comparison of the pseudo sidescan image with actual Hydrosweep sidescan image, from an area covering a pear shaped seamount...

  12. Characterization of nuclear physics targets using Rutherford backscattering and particle induced X-ray emission

    International Nuclear Information System (INIS)

    Rubehn, T.; Wozniak, G.J.; Phair, L.; Moretto, L.G.; Yu, K.M.


    Rutherford backscattering and particle induced X-ray emission have been utilized to precisely characterize targets used in nuclear fission experiments. The method allows for a fast and non-destructive determination of target thickness, homogeneity and element composition. (orig.)

  13. Backscatter 0.5m TIFF Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography...

  14. Extracting integrated and differential cross sections in low energy heavy-ion reactions from backscattering measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sargsyan, V. V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Yerevan State University, 0025 Yerevan (Armenia); Adamian, G. G., E-mail: [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Antonenko, N. V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Mathematical Physics Department, Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Diaz-Torres, A. [European Centre for Theoretical Studies in Nuclear Physics and Related Areas, I-38123 Villazzano, Trento (Italy); Gomes, P. R. S. [de Fisica, Universidade Federal Fluminense, Av. Litorânea, s/n, Niterói, R.J. 24210-340 (Brazil); Lenske, H. [Institut für Theoretische Physik der Justus–Liebig–Universität, D–35392 Giessen (Germany)


    We suggest new methods to extract elastic (quasi-elastic) scattering angular distribution and reaction (capture) cross sections from the experimental elastic (quasi-elastic) backscattering excitation function taken at a single angle.

  15. Assessing the contamination of SuperDARN global convection maps by non-F-region backscatter

    Directory of Open Access Journals (Sweden)

    G. Chisham


    Full Text Available Global convection mapping using line-of-sight Doppler velocity data from the Super Dual Auroral Radar Network (SuperDARN is now an accepted method of imaging high-latitude ionospheric convection. This mapping process requires that the flow measured by the radars is defined solely by the convection electric field. This is generally only true of radar backscatter from the ionospheric F-region. We investigate the extent to which the E-region and ground backscatter in the SuperDARN data set may be misidentified as F-region backscatter, and assess the contamination of global convection maps which results from the addition of this non-F-region backscatter. We present examples which highlight the importance of identifying this contamination, especially with regard to the mesoscale structure in the convection maps.Key words. Ionosphere (plasma convection – Radio science (radio wave propagation; instruments and techniques

  16. Characterizing biogenous sediments using multibeam echosounder backscatter data - Estimating power law parameter utilizing various models

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Kodagali, V.N.

    In this paper, Helmholtz-Kirchhoff (H-K) roughness model is employed to characterize seafloor sediment and roughness parameters from the eastern sector of the Southern Oceans The multibeam- Hydroswcep system's angular-backscatter data, which...

  17. Fine scale analyses of a coralline bank mapped using multi-beam backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Menezes, A.A.A.; Naik, M.; Fernandes, W.A.; Haris, K.; Chakraborty, B.; Estiberio, S.; Lohani, R.B.

    unsupervised self-organizing maps (SOM) architecture is used to determine the existence of six classes. Thereafter, 55 segments were identified for data segmentation, employing six profiles selected from the backscatter maps, using the fuzzy c-means (FCM...

  18. Impact of sound attenuation by suspended sediment on ADCP backscatter calibrations

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Vermeulen, B.


    Although designed for velocity measurements, acoustic Doppler current profilers (ADCPs) are widely being used to monitor suspended particulate matter in rivers and in marine environments. To quantify mass concentrations of suspended matter, ADCP backscatter is generally calibrated with in situ

  19. Simrad em3002d Backscatter imagery of Penguin Bank, Molokai, Hawaii, USA (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Backscatter imagery extracted from gridded bathymetry of Penguin Bank, Molokai, Hawaii, USA. These data provide almost complete coverage between 0 and 100 meters....


    National Aeronautics and Space Administration — This data set consists of a VICAR2 format image of Venus large-angle radar backscatter cross section, from the side-looking mode of the Pioneer Venus radar mapper...

  1. Investigating an Instrument for Measurement of Hyperspectral Backscattering in Natural Waters, Phase II (United States)

    National Aeronautics and Space Administration — The remote sensing reflectance signal measured by an ocean color satellite is to first order proportional to the ratio of backscattered to absorbed light. Therefore...

  2. Backscatter 0.5m TIFF Mosaic of St. Thomas, US Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  3. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Thomas, US Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  4. A comparison of satellite scintillation measurements with HF radar backscatter characteristics

    Directory of Open Access Journals (Sweden)

    S. E. Milan


    Full Text Available We examine the correspondence between high latitude ionospheric scintillation measurements made at 250MHz with the occurrence of 10MHz HF coherent radar backscatter, on 13 and 14 December 2002. We demonstrate that when the ionospheric intersection point of the scintillation measurements is co-located with significant HF radar backscatter, the observed scintillation, quantified by the S4 index, is elevated. Conversely, when the radar indicates that backscatter is observed away from the intersection point due to movements of the auroral zone, the observed scintillation is low. This suggests that scintillation is highly location-dependent, being enhanced in the auroral zone and being lower at sub-auroral latitudes. The coexistence of scintillation and HF radar backscatter, produced by ionospheric density perturbations with scale sizes of 100s of metres and ~15 m, respectively, suggests that a broad spectrum of density fluctuations is found in the auroral zone.

  5. Automatically determining the origin direction and propagation mode of high-frequency radar backscatter (United States)

    Burrell, Angeline G.; Milan, Stephen E.; Perry, Gareth W.; Yeoman, Timothy K.; Lester, Mark


    Elevation angles of returned backscatter are calculated at Super Dual Auroral Radar Network radars using interferometric techniques. These elevation angles allow the altitude of the reflection point to be estimated, an essential piece of information for many ionospheric studies. The elevation angle calculation requires knowledge of the azimuthal return angle. This directional angle is usually assumed to lie along a narrow beam from the front of the radar, even though the signals are known to return from both in front of and behind the radar. If the wrong direction of return is assumed, large uncertainties will be introduced through the azimuthal return angle. This paper introduces a means of automatically determining the correct direction of arrival and the propagation mode of backscatter. The application of this method will improve the accuracy of backscatter elevation angle data and aid in the interpretation of both ionospheric and ground backscatter observations.

  6. Backscattered Helium Spectroscopy in the Helium Ion Microscope: Principles, Resolution and Applications

    NARCIS (Netherlands)

    van Gastel, Raoul; Hlawacek, G.; Dutta, S.; Poelsema, Bene


    We demonstrate the possibilities and limitations for microstructure characterization using backscattered particles from a sharply focused helium ion beam. The interaction of helium ions with matter enables the imaging, spectroscopic characterization, as well as the nanometer scale modification of

  7. Morphology of pockmarks along the western continental margin of India: Employing multibeam bathymetry and backscatter data

    Digital Repository Service at National Institute of Oceanography (India)

    Dandapath, S.; Chakraborty, B.; Karisiddaiah, S.M.; Menezes, A.A.A.; Ranade, G.; Fernandes, W.A.; Naik, D.K.; PrudhviRaju, K.N.

    This study addresses the morphology of pockmarks along the western continental margin of India using multibeam bathymetry and backscatter data. Here, for the first time we have utilized the application of ArcGIS (Geographical Information System...

  8. Uranium absorption study pile

    International Nuclear Information System (INIS)

    Raievski, V.; Sautiez, B.


    The report describes a pile designed to measure the absorption of fuel slugs. The pile is of graphite and comprises a central section composed of uranium rods in a regular lattice. RaBe sources and BF 3 counters are situated on either side of the center. A given uranium charge is compared with a specimen charge of about 560 kg, and the difference in absorption between the two noted. The sensitivity of the equipment will detect absorption variations of about a few ppm boron (10 -6 boron per gr. of uranium) or better. (author) [fr

  9. Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds (United States)

    Buscombe, D.; Grams, P. E.; Kaplinski, M. A.


    Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

  10. Analysis of a nuclear backscattering and reaction data by the method of convolution integrals

    International Nuclear Information System (INIS)

    Lewis, M.B.


    A quantitative description of nuclear backscattering and reaction processes is made. Various formulas pertinent to nuclear microanalysis are assembled in a manner useful for experimental application. Convolution integrals relating profiles of atoms in a metal substrate to the nuclear reaction spectra obtained in the laboratory are described and computed. Energy straggling and multiple scattering are explicitly included and shown to be important. Examples of the application of the method to simple backscattering, oxide films, and implanted gas are discussed. 7 figures, 1 table

  11. Radio-analysis of hydrogenous material using neutron back-scattering technique

    International Nuclear Information System (INIS)

    Holly, Wiam Ahmed Alteghany


    In this work, we have explored the possibility of using neutron back-scattering technique in performing radio analysis for samples of hydrogenous materials such as explosives, drugs, crude oil and water, looking for different signals that may be used to discriminate these samples. Monte Carlo simulations were carried out to model the detection system and select the optimal geometry as well. The results were determined in terms of the energy spectra of the back-scattered neutrons.(Author)

  12. Ambient Backscatter Networking: A Novel Paradigm to Assist Wireless Powered Communications


    Lu, Xiao; Niyato, Dusit; Jiang, Hai; Kim, Dong In; Xiao, Yong; Han, Zhu


    Ambient backscatter communication technology has been introduced recently, and is then quickly becoming a promising choice for self-sustainable communication systems as an external power supply or a dedicated carrier emitter is not required. By leveraging existing RF signal resources, ambient backscatter technology can support sustainable and independent communications and consequently open up a whole new set of applications that facilitate Internet-of-Things (IoT). In this article, we study ...

  13. Probing turbid medium structure using ultra low coherence enhanced backscattering spectroscopy (United States)

    DeAngelo, Bianca; Arzumanov, Grant; Matovu, Charles; Shanley, Patrick; Zeylikovich, Joseph; Xu, M.


    We report on experimental results and theoretical investigation on probing the structure of turbid medium using ultra low coherence enhanced backscattering spectroscopy where the spatial coherence length of the incident line light is not greater than 25 μm. The periodic structure contained in the low coherence enhanced backscattering spectroscopy is found to decrease with the dominant scatterer size. A theoretical model is proposed to explain the observations and is verified by Monte Carlo simulations.

  14. Seabottom characterization using multibeam echosounder angular backscatter: An application of the composite roughness theory

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Schenke, H.W.; Kodagali, V.N.; Hagen, R.

    multibeam echosounding systems reveal significant results related to seabottom geological processes ([3] and references therein). Jackson et al., [1] had proposed simultaneous application of the two backscatter theories related to the large and small... to acquire multibeam deep ocean seabottom backscatter data of higher angular range (62 20 14 incidence angle). However, with the commercial availability of the multibeam-Hydrosweep system [4], which operates at a 45 14 half fan width, it has become possible...

  15. Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter


    A. Senior; M. J. Kosch; T. K. Yeoman; M. T. Rietveld; I. W. McCrea


    International audience; Observations of HF radar backscatter from artificial field-aligned irregularities in an ionosphere perturbed by travelling disturbances due to atmospheric gravity waves are presented. Some features of the spatio-temporal structure of the artificial radar backscatter can be explained in terms of the distortion of the ionosphere resulting from the travelling disturbances. The distorted ionosphere can allow the HF pump wave to access upper-hybrid resonance at larger dista...

  16. Correction of optical absorption and scattering variations in Laser Speckle Rheology measurements. (United States)

    Hajjarian, Zeinab; Nadkarni, Seemantini K


    Laser Speckle Rheology (LSR) is an optical technique to evaluate the viscoelastic properties by analyzing the temporal fluctuations of backscattered speckle patterns. Variations of optical absorption and reduced scattering coefficients further modulate speckle fluctuations, posing a critical challenge for quantitative evaluation of viscoelasticity. We compare and contrast two different approaches applicable for correcting and isolating the collective influence of absorption and scattering, to accurately measure mechanical properties. Our results indicate that the numerical approach of Monte-Carlo ray tracing (MCRT) reliably compensates for any arbitrary optical variations. When scattering dominates absorption, yet absorption is non-negligible, diffusing wave spectroscopy (DWS) formalisms perform similar to MCRT, superseding other analytical compensation approaches such as Telegrapher equation. The computational convenience of DWS greatly simplifies the extraction of viscoelastic properties from LSR measurements in a number of chemical, industrial, and biomedical applications.

  17. Artificially controlled backscattering in single mode fibers based on femtosecond laser fabricated reflectors (United States)

    Wang, Xiaoliang; Chen, Daru; Li, Haitao; Wu, Qiong


    A novel method to artificially control the backscattering of the single-mode fiber (SMF) is proposed and investigated for the first time. This method can help to fabricate a high backscattering fiber (HBSF), such as by fabricating reflectors in every one meter interval of an SMF based on the exposure of the femtosecond laser beam. The artificially controlled backscattering (ACBS) can be much higher than the natural Rayleigh backscattering (RB) of the SMF. The RB power and ACBS power in the unit length fiber are derived according to the theory of the RBS. The total relative power and the relative back power reflected in the unit length of the HBSF have been simulated and presented. The simulated results show that the HBSF has the characteristics of both low optical attenuation and high backscattering. The relative back power reflected in the unit length of the HBSF is 25dB larger than the RB power of the SMF when the refractive index modulation quantity of the reflectors is 0.009. Some preliminary experiments also indicate that the method fabricating reflectors to increase the backscattering power of the SMF is practical and promising.

  18. Multi-temporal RADARSAT-1 and ERS backscattering signatures of coastal wetlands in southeastern Louisiana (United States)

    Kwoun, Oh-Ig; Lu, Z.


    Using multi-temporal European Remote-sensing Satellites (ERS-1/-2) and Canadian Radar Satellite (RADARSAT-1) synthetic aperture radar (SAR) data over the Louisiana coastal zone, we characterize seasonal variations of radar backscat-tering according to vegetation type. Our main findings are as follows. First, ERS-1/-2 and RADARSAT-1 require careful radiometric calibration to perform multi-temporal backscattering analysis for wetland mapping. We use SAR backscattering signals from cities for the relative calibration. Second, using seasonally averaged backscattering coefficients from ERS-1/-2 and RADARSAT-1, we can differentiate most forests (bottomland and swamp forests) and marshes (freshwater, intermediate, brackish, and saline marshes) in coastal wetlands. The student t-test results support the usefulness of season-averaged backscatter data for classification. Third, combining SAR backscattering coefficients and an optical-sensor-based normalized difference vegetation index can provide further insight into vegetation type and enhance the separation between forests and marshes. Our study demonstrates that SAR can provide necessary information to characterize coastal wetlands and monitor their changes.

  19. Relationship between ultrasonic backscatter and trabecular thickness in human calcaneus: theory and experiment (United States)

    Wear, Keith A.; Laib, Andres


    Trabecular thickness within cancellous bone is an important determinant of osteoporotic fracture risk. Noninvasive assessment of trabecular thickness could potentially yield useful diagnostic information. Faran's theory of elastic scattering from a cylindrical object immersed in a fluid has been employed to predict the dependence of ultrasonic backscatter on trabecular thickness. Methodology to test this theory has been validated in experiments using nylon fishing lines spanning a wide range of diameters. In the case of bone, Faran's theory predicts that, in the range of morphological and material properties expected for trabecular bone, the backscatter coefficient at 500 kHz should be approximately proportional to trabecular thickness to the power of 2.9. Experimental measurements of backscatter coefficient were performed on 43 human calcaneus samples in vitro. Mean trabecular thicknesses on the 43 samples were assessed using micro computed tomography. A power law fit to the data showed that the backscatter coefficient empirically varied as trabecular thickness to the 2.8 power. The 95% confidence interval for this exponent was 1.7 to 3.9. The square of the correlation coefficient for the linear regression to the log transformed data was 0.40. This suggests that 40% of variations in backscatter may be attributed to variations in trabecular thickness. These results (1) reinforce previous studies that offered validation for the Faran cylinder model for prediction of scattering properties of cancellous bone, and (2) provide added evidence for the potential diagnostic utility of the backscatter measurement.

  20. Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars (United States)

    Lamarche, Geoffroy; Lurton, Xavier


    Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group ( has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working group, and a synopsis of the BSWG Guidelines and Recommendations to date. The paper includes (1) an overview of the current status in sensors and techniques available in seafloor backscatter data from multibeam sonars; (2) the presentation of the BSWG structure and results; (3) recommendations to operators, end-users, sonar manufacturers, and software developers using sonar backscatter for seafloor-mapping applications, for best practice methods and approaches for data acquisition and processing; and (4) a discussion on the development needs for future systems and data processing. We propose for the first time a nomenclature of backscatter processing levels that affords a means to accurately and efficiently describe the data processing status, and to facilitate comparisons of final products from various origins.

  1. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning......Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...

  2. Absorption fluids data survey (United States)

    Macriss, R. A.; Zawacki, T. S.

    Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

  3. Absorption cooling device. Absorptions-Kuehlvorrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Bourne, J.; Vardi, I.; Kimchi, Y.; Ben-Dror, J.


    The invention concerns improvements of absorption refrigerators, where a lithium chloride or lithium bromide/water cycle is used. According to the invention an inner separating or dividing structure between different functional parts of a machine of this type is provided. The structure contains two sections of wall, which are separated from one another by a suitable space, in order to achieve thermal insulation. This air space is provided with an opening in the direction towards the inside of the container and the opening is shielded to prevent the entry of liquids (in liquid or spray form).

  4. A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available A poleward-progressing 630 nm optical feature is observed between approximately 0100 UT and 0230 UT (0400 MLT to 0530 MLT by a meridian-scanning photometer (MSP located at Ny Ålesund, Svalbard. Simultaneous coherent HF radar measurements indicate a region of poleward-expanding backscatter with rapid sunward plasma flow velocity along the MSP meridian. Spatial maps of the backscatter indicate a stationary backscatter feature aligned obliquely with respect to the MSP meridian, which produces an impression of poleward-expansion as the MSP progresses to later MLT. Two interpretations of the observations are possible, depending on whether the arc system is considered to move (time-dependent or to be stationary in time and apparent motion is produced as the MSP meridian rotates underneath it (time-independent. The first interpretation is as a poleward motion of an east-west aligned auroral arc. In this case the appearance of the region of backscatter is not associated with the optical feature, though the velocities within it are enhanced when the two are co-located. The second interpretation is as a polar arc or theta aurora, common features of the polar cap under the prevailing IMF northwards conditions. In this case the backscatter appears as an approximately 150 km wide region adjacent to the optical arc. In both interpretations the luminosity of the optical feature appears related to the magnitude of the plasma flow velocity. The optical features presented here do not generate appreciable HF coherent backscatter, and are only identifiable in the backscatter data as a modification of the flow by the arc electrodynamics.

  5. Mitigating the effect of optical back-scatter in multispectral underwater imaging

    International Nuclear Information System (INIS)

    Mortazavi, Halleh; Oakley, John P; Barkat, Braham


    Multispectral imaging is a very useful technique for extracting information from the underwater world. However, optical back-scatter changes the intensity value in each spectral band and this distorts the estimated spectrum. In this work, a filter is used to detect the level of optical back-scatter in each spectral band from a set of multispectral images. Extraction of underwater object spectra can be done by subtracting the estimated level of optical back-scatter and scaling the remainder in each spectral band from the captured image in the corresponding band. An experiment has been designed to show the performance of the proposed filter for correcting the set of multispectral underwater images and recovering the pixel spectra. The multispectral images are captured by a B/W CCD digital camera with a fast tunable liquid-crystal filter in 33 narrow spectral bands in clear and different levels of turbid water. Reference estimates for the optical back-scatter spectra are found by comparing a clear and a degraded set of multispectral images. The accuracy and consistency of the proposed method, the extended Oakley–Bu cost function, is examined by comparing the estimated values with the reference level of an optical back-scatter spectrum. The same comparison is made for the simple estimation approach. The results show that the simple method is not reliable and fail to estimate the level of optical back-scatter spectrum accurately. The results from processing experimental images in turbid water show that the effect of optical back-scatter can be mitigated in the image of each spectral band and, as a result, the spectra of the object can be recovered. However, for a very high level of turbid water the recovery is limited because of the effect of extinction. (paper)

  6. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars (United States)

    Milan, S. E.; Jones, T. B.; Robinson, T. R.; Thomas, E. C.; Yeoman, T. K.


    Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north) of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter. Acknowledgements. The authors are grateful to Prof. D. J. Southwood (Imperial College, London), J. C. Samson (University of Alberta, Edmonton), L. J. Lanzerotti (AT&T Bell Laboratories), A. Wolfe (New York City Technical College) and to Dr. M. Vellante (University of LÁquila) for helpful discussions. They also thank Dr. A. Meloni (Istituto Nazionale di Geofisica, Roma) who made available geomagnetic field observations from LÁquila Geomagnetic Observatory. This research activity at LÁquila is supported by MURST (40% and 60% contracts) and by GIFCO/CNR. Topical Editor K.-H. Glaßmeier thanks C. Waters and S. Fujita for their help in evaluating this paper.-> Correspondence to :P. Francia->

  7. Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought (United States)

    Hagen, Stephen; Braswell, Bobby; Milliman, Tom; Herrick, Christina; Peterson, Seth; Roberts, Dar; Keller, Michael; Palace, Michael


    Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999–2009, and low morning backscatter persisted for 2006–2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts. PMID:28873422

  8. Vitamin A absorption

    International Nuclear Information System (INIS)

    Baker, S.J.


    Investigation of the absorption of vitamin A and related substances is complicated by the multiplicity of forms in which they occur in the diet and by the possibility that they may be subject to different mechanisms of absorption. Present knowledge of these mechanisms is inadequate, especially in the case of carotenoids. Numerous tests of absorption have been developed. The most common has been the biochemical measurement of the rise in plasma vitamin A after an oral dose of retinol or retinyl ester, but standardization is inadequate. Radioisotope tests based upon assay of serum or faecal activity following oral administration of tritiated vitamin A derivaties hold considerable promise, but again standardization is inadequate. From investigations hitherto performed it is known that absorption of vitamin A is influenced by several diseases, although as yet the consistency of results and the correlation with other tests of intestinal function have often been poor. However, the test of vitamin A absorption is nevertheless of clinical importance as a specialized measure of intestinal function. (author)

  9. Synergic use of TOMS and AERONET observations for characterization of aerosol absorption (United States)

    Torres, O.; Sinyuk, A.; Bhartia, P. K.; Dubovik, O.; Holben, B.


    The role of aerosol absorption on the radiative transfer balance of the earth-atmosphere system is one of the largest sources of uncertainty in the analysis of global climate change. Global measurements of aerosol single scattering albedo are, therefore, necessary to properly assess the radiative forcing effect of aerosols. Remote sensing of aerosol absorption is currently carried out using both ground (Aerosol Robotic Network) and space (Total Ozone Mapping Spectrometer) based observations. The satellite technique uses measurements of backscattered near ultraviolet radiation. Carbonaceous aerosols, resulting from the combustion of biomass, are one of the most predominant absorbing aerosol types in the atmosphere. In this presentation, TOMS and AERONET retrievals of single scattering albedo of carbonaceous aerosols, are compared for different environmental conditions: agriculture related biomass burning in South America and Africa and peat fires in Eastern Europe. The AERONET and TOMS derived aerosol absorption information are in good quantitative agreement. The most absorbing smoke is detected over the African Savanna. Aerosol absorption over the Brazilian rain forest is less absorbing. Absorption by aerosol particles resulting from peat fires in Eastern Europe is weaker than the absorption measured in Africa and South America. This analysis shows that the near UV satellite method of aerosol absorption characterization has the sensitivity to distinguish different levels of aerosol absorption. The analysis of the combined AERONET-TOMS observations shows a high degree of synergy between satellite and ground based observations.

  10. Gastrointestinal absorption of plutonium

    International Nuclear Information System (INIS)

    Larsen, R.P.; Oldham, R.D.; Bhattacharyya, M.H.; Moretti, E.S.; Austin, D.J.


    An investigation has been made of the effect of the oxidation state of plutonium on its absorption from the gastrointestinal tract. For mice and rats that have been starved prior to gastrointestinal administration, there is no significant difference between the absorption factors for Pu(IV) and Pu(VI). The value obtained for Pu(VI) is an order of magnitude lower than that reported previously. The value obtained for Pu(IV) is two orders of magnitude higher than those reported previously for nitrate solutions and the same as those reported for citrate solutions

  11. Quantum Absorption Refrigerator (United States)

    Levy, Amikam; Kosloff, Ronnie


    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power Jc vanishes as Jc∝Tcα, when Tc→0, where α=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath.

  12. User expectations for multibeam echo sounders backscatter strength data-looking back into the future (United States)

    Lucieer, Vanessa; Roche, Marc; Degrendele, Koen; Malik, Mashkoor; Dolan, Margaret; Lamarche, Geoffroy


    With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing capabilities, navigation, and graphic display devices, have improved the resolution and particularly the dynamic range available to sonar and processing software manufacturers. Alongside these improvements the expectations of what the data can deliver has also grown. In this paper, we identify these user-expectations and explore how MBES backscatter is utilized by different communities involved in marine seabed research at present, and the aspirations that these communities have for the data in the future. The results presented here are based on a user survey conducted by the GeoHab (Marine Geological and Biological Habitat Mapping) association. This paper summarises the different processing procedures employed to extract useful information from MBES backscatter data and the various intentions for which the user community collect the data. We show how a range of backscatter output products are generated from the different processing procedures, and how these results are taken up by different scientific disciplines, and also identify common constraints in handling MBES BS data. Finally, we outline our expectations for the future of this unique and important data source for seafloor mapping and characterisation.

  13. Coherent Backscattering and Opposition Effects Observed in Some Atmosphereless Bodies of the Solar System (United States)

    Dlugach, Zh. M.; Mishchenko, M. I.


    The results of photometric and polarimetric observations carried out for some bright atmosphere-less bodies of the Solar system near the zero phase angle reveal the simultaneous existence of two spectacular optical phenomena, the so-called brightness and polarization opposition effects. In a number of studies, these phenomena were explained by the influence of coherent backscattering. However, in general, the interference concept of coherent backscattering can be used only in the case where the particles are in the far-field zones of each other, i.e., when the scattering medium is rather rarefied. Because of this, it is important to prove rigorously and to demonstrate that the coherent backscattering effect may also exist in densely packed scattering media like regolith surface layers of celestial bodies. From the results of the computer modeling performed with the use of numerically exact solutions of the macroscopic Maxwell equations for discrete random media with different packing densities of particles, we studied the origin and evolution of all the opposition phenomena predicted by the coherent backscattering theory for low-packing-density media. It has been shown that the predictions of this theory remain valid for rather high-packing densities of particles that are typical, in particular, of regolith surfaces of the Solar system bodies. The results allow us to conclude that both opposition effects observed simultaneously in some high-albedo atmosphereless bodies of the Solar system are caused precisely by coherent backscattering of solar light in the regolith layers composed of microscopic particles.

  14. Optimization of phantom backscatter thickness and lateral scatter volume for radiographic film dosimetry

    International Nuclear Information System (INIS)

    Srivastava, R.P.; De Wagter, C.


    The aim of this study is to determine the optimal backscatter thickness and lateral phantom dimension beyond the irradiated volume for the dosimetric verification with radiographic film when applying large field sizes. Polystyrene and Virtual Water™ phantoms were used to study the influence of the phantom backscatter thickness. EDR2 and XV films were used in 6 and 18 MV photon beams. The results show 11.4% and 6.4% over-response of the XV2 film when compared to the ion chamber for 6 MV 30×30 and 10×10 cm 2 field sizes, respectively, when the phantom backscatter thickness is 5 cm. For the same setup, measurements with EDR2 films indicate 8.5% and 1.7% over-response. The XV2 film response in the polystyrene phantom is about 2.0% higher than in the Virtual Water™ phantom for the 6 MV beam and 20 cm backscatter thickness. Similar results were obtained for EDR2 film. In the lateral scatter study, film response was nearly constant within 5 cm of lateral thickness and it increases when lateral thickness increases due to more multiple scatter of low energy photons. The backscatter thickness of the phantom should be kept below 7 cm for the accuracy of the film dosimetry. The lateral extension of the phantom should not be more than 5 cm from the field boundary in case of large irradiated volumes.

  15. Backscatter measurements of aerosolized CB simulants with a frequency agile CO2 lidar (United States)

    Vanderbeek, Richard; Gurton, Kristan


    A novel windowless chamber was developed to allow aerosol backscatter measurements with a frequency-agile CO2 lidar. The chamber utilizes curtains of air to contain the cloud, thus preventing the inevitable backscatter off of conventional windows from corrupting the desired measurements. This feature is critical because the CO2 lidar has a long (1 μs) pulse and the backscatter off the window cannot be temporally separated from the backscatter off the aerosol in the chamber. The chamber was designed for testing with a variety of CB simulants and interferents in both vapor and aerosol form and has been successfully shown to contain a cloud of known size, concentration, and particle size distribution for 10-15 minutes. This paper shows the results using Arizona road dust that was screened by the manufacturer into 0-3 μm and 5-10 μm particle size distributions. The measurements clearly show the effect of size distribution on the infrared backscatter coefficients as well as the dynamic nature of the size distribution for a population of aerosols. The test methodology and experimental results are presented.

  16. Quantitative Analysis of Venus Radar Backscatter Data in ArcGIS (United States)

    Long, S. M.; Grosfils, E. B.


    Ongoing mapping of the Ganiki Planitia (V14) quadrangle of Venus and definition of material units has involved an integrated but qualitative analysis of Magellan radar backscatter images and topography using standard geomorphological mapping techniques. However, such analyses do not take full advantage of the quantitative information contained within the images. Analysis of the backscatter coefficient allows a much more rigorous statistical comparison between mapped units, permitting first order selfsimilarity tests of geographically separated materials assigned identical geomorphological labels. Such analyses cannot be performed directly on pixel (DN) values from Magellan backscatter images, because the pixels are scaled to the Muhleman law for radar echoes on Venus and are not corrected for latitudinal variations in incidence angle. Therefore, DN values must be converted based on pixel latitude back to their backscatter coefficient values before accurate statistical analysis can occur. Here we present a method for performing the conversions and analysis of Magellan backscatter data using commonly available ArcGIS software and illustrate the advantages of the process for geological mapping.

  17. Effects of fatty infiltration in human livers on the backscattered statistics of ultrasound imaging. (United States)

    Wan, Yung-Liang; Tai, Dar-In; Ma, Hsiang-Yang; Chiang, Bing-Hao; Chen, Chin-Kuo; Tsui, Po-Hsiang


    Ultrasound imaging has been widely applied to screen fatty liver disease. Fatty liver disease is a condition where large vacuoles of triglyceride fat accumulate in liver cells, thereby altering the arrangement of scatterers and the corresponding backscattered statistics. In this study, we used ultrasound Nakagami imaging to explore the effects of fatty infiltration in human livers on the statistical distribution of backscattered signals. A total of 107 patients volunteered to participate in the experiments. The livers were scanned using a clinical ultrasound scanner to obtain the raw backscattered signals for ultrasound B-mode and Nakagami imaging. Clinical scores of fatty liver disease for each patient were determined according to a well-accepted sonographic scoring system. The results showed that the Nakagami image can visualize the local backscattering properties of liver tissues. The Nakagami parameter increased from 0.62 ± 0.11 to 1.02 ± 0.07 as the fatty liver disease stage increased from normal to severe, indicating that the backscattered statistics vary from pre-Rayleigh to Rayleigh distributions. A significant positive correlation (correlation coefficient ρ = 0.84; probability value (p value) applications in fatty liver disease diagnosis. © IMechE 2015.

  18. Angular random walk limited by Rayleigh backscattering in resonator fiber optic gyros. (United States)

    Jiang, Zhiguo; Hu, Zongfu; Fu, Changsong


    This paper is concerned with the angular random walk (ARW) limited by Rayleigh backscattering in the resonator fiber optic gyro (RFOG) with a light source of arbitrary temporal coherence. First, a model of Rayleigh backscattering noise in RFOGs is established to predict the fluctuation characteristics of backscattered intensity and interference intensity. Next, the formula for the ARW limited by Rayleigh backscattering is derived, and the requirement of carrier suppression level is calculated to make sure the ARW is limited by the detector's shot noise rather than Rayleigh scattering noise. Finally, the influences of the cavity length, the linewidth, and the finesse on the ARW limited by Rayleigh backscattering are investigated. The results predict that the influence of the cavity length L and the laser linewidth Δυ L on the ARW is dominantly related to the factor e -2πΔυ L n e L/c , and under the finesse 88, the best ARW is obtained when there is a relation L·Δυ L ≈4×10 5   m·Hz.

  19. Investigation on LPCVD SiON films by means of Rutherford backscattering, FT-IR and UV-VIS Spectroscopy

    International Nuclear Information System (INIS)

    Dudu, D.; Ivanov, E.; Bercu, B.N.; Bercu, M.; Modreanu, M.


    The SiON layers deposited by LPCVD (Low Vapour Chemical Deposition ) on Si (111) substrate has been investigated by complementary techniques as Rutherford backscattering and optical spectroscopy. We have determined the evolution of chemical content in respect with oxygen relative to nitrogen. The change in oxygen content versus time was produced by exposing the sample in wet oxygen at 1000 deg. C for different periods. The change in oxygen amount was determined by monitoring the Si-O-Si integral intensity of the absorption band at 1071cm -1 . Also the behavior of the refractive index versus time in an oxidative atmosphere gave a complementary information about the oxygen content. Alpha scattering spectra obtained by means of cyclotron facilities was used as another technique for oxygen to nitrogen ratio determination. Both visible spectra and RBS data were fitted by using the corresponding simulating approaches based on light propagation in non-homogeneous media and respectively on multiple scattering theory. The time evolution of O content indicated a diffused controlled process through the gas/solid interface. (authors)

  20. Retrieval method of aerosol extinction coefficient profile based on backscattering, side-scattering and Raman-scattering lidar (United States)

    Shan, Huihui; Zhang, Hui; Liu, Junjian; Tao, Zongming; Wang, Shenhao; Ma, Xiaomin; Zhou, Pucheng; Yao, Ling; Liu, Dong; Xie, Chenbo; Wang, Yingjian


    Aerosol extinction coefficient profile is an essential parameter for atmospheric radiation model. It is difficult to get higher signal to noise ratio (SNR) of backscattering lidar from the ground to the tropopause especially in near range. Higher SNR problem can be solved by combining side-scattering and backscattering lidar. Using Raman-scattering lidar, aerosol extinction to backscatter ratio (lidar ratio) can be got. Based on side-scattering, backscattering and Raman-scattering lidar system, aerosol extinction coefficient is retrieved precisely from the earth's surface to the tropopause. Case studies show this method is reasonable and feasible.

  1. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj


    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...

  2. Neutron resonance absorption theory

    International Nuclear Information System (INIS)

    Reuss, P.


    After some recalls on the physics of neutron resonance absorption during their slowing down, this paper presents the main features of the theoretical developments performed by the french school of reactor physics: the effective reaction rate method so called Livolant-Jeanpierre theory, the generalizations carried out by the author, and the probability table method [fr

  3. Absorption and scattering effects by silver nanoparticles near the interface of organic/inorganic semiconductor tandem films

    International Nuclear Information System (INIS)

    Nemes, Coleen T.; Vijapurapu, Divya K.; Petoukhoff, Christopher E.; Cheung, Gary Z.; O’Carroll, Deirdre M.


    We experimentally and theoretically characterize back-scattering and extinction of Ag nanoparticle (AgNP) arrays on both Si wafer substrates and optically-thick Ag substrates with and without organic poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) bulk-heterojunction thin film coatings. A strong red-shift in back-scattered light wavelength occurs from AgNP arrays on Si as a function of increasing mean nanoparticle diameter (ranging from 30 to 90 nm). Back-scattering from the AgNP array is notably quenched in the wavelength range of strong P3HT absorption when the organic layer is applied. However, back-scattering is enhanced to a degree relative to the uncoated AgNP array on Si at wavelengths greater than the absorption band edge of P3HT. For comparison, the optical properties of AgNPs on an optically-thick Ag substrate are reported with and without P3HT:PCBM thin film coatings. On the reflective Ag substrates, a significant enhancement (by a factor of 7.5) and red-shift of back-scattered light occurred upon coating of the AgNPs with the P3HT:PCBM layer. Additionally, red-edge extinction was enhanced in the P3HT:PCBM layer with the presence of the AgNPs compared to the planar case. Theoretical electromagnetic simulations were carried out to help validate and explain the scattering and extinction changes observed in experiment. Both increasing nanoparticle size and an increasing degree of contact with the Si substrate (i.e., effective index of the nanoparticle environment) are shown to play a role in increasing back- and forward-scattering intensity and wavelength, and in increasing absorption enhancements in both the organic and Si layers. AgNPs placed at the P3HT:PCBM/Si interface give rise to absorption increases in P3HT of up to 18 %, and only enhance Si absorption at wavelengths longer than the absorption band edge of P3HT (by almost 90 % in the 660–1,200 nm wavelength range). These results provide insight into how metal

  4. Direct detection of near-surface faults by migration of back-scattered surface waves

    KAUST Repository

    Yu, Han


    We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps are to isolate the back-scattered surface waves, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. A deconvolution filter derived from the data can be used to collapse a dispersive arrival into a non-dispersive event. Results with synthetic data and field records validate the feasibility of this method. Applying this method to USArray data or passively recorded exploration data might open new opportunities in mapping tectonic features over the extent of the array.

  5. Determination of effective atomic number of composite materials using backscattered gamma photons - A novel method (United States)

    Hosamani, M. M.; Badiger, N. M.


    The effective atomic number (Zeff) of composite materials has been determined by measuring the backscattered gamma photons at 180°. A 661.6 keV gamma photons from 137Cs radioactive source are allowed to scatter at an angle of 180° from the sample. The backscattered photons at 180° from the sample are detected with "2 × 2″ NaI(Tl) scintillation gamma ray spectrometer coupled to 16 K Multi Channel Analyzer (MCA). It is observed experimentally that the intensity of backscattered photons increases initially with increasing the thickness of the target and then it becomes saturated above a certain thickness. By knowing the saturated thickness values for known atomic number of the elemental targets, the Zeff of composite materials has been determined. The experimentally measured Zeff values have been compared with theoretical values predicted by direct method, power law method and AutoZeff code.

  6. Bathymetry and acoustic backscatter: outer mainland shelf and slope, Gulf of Santa Catalina, southern California (United States)

    Dartnell, Peter; Conrad, James E.; Ryan, Holly F.; Finlayson, David P.


    In 2010 and 2011, scientists from the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, acquired bathymetry and acoustic-backscatter data from the outer shelf and slope region offshore of southern California. The surveys were conducted as part of the USGS Marine Geohazards Program. Assessment of the hazards posed by offshore faults, submarine landslides, and tsunamis are facilitated by accurate and detailed bathymetric data. The surveys were conducted using the USGS R/V Parke Snavely outfitted with a 100-kHz Reson 7111 multibeam-echosounder system. This report provides the bathymetry and backscatter data acquired during these surveys in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

  7. Sensitivity improvement of a laser interferometer limited by inelastic back-scattering, employing dual readout

    International Nuclear Information System (INIS)

    Meinders, Melanie; Schnabel, Roman


    Inelastic back-scattering of stray light is a long-standing and fundamental problem in high-sensitivity interferometric measurements and a potential limitation for advanced gravitational-wave (GW) detectors. The emerging parasitic interferences cannot be distinguished from a scientific signal via conventional single readout. In this work, we propose the subtraction of inelastic back-scatter signals by employing dual homodyne detection on the output light, and demonstrate it for a table-top Michelson interferometer. The additional readout contains solely parasitic signals and is used to model the scatter source. Subtraction of the scatter signal reduces the noise spectral density and thus improves the measurement sensitivity. Our scheme is qualitatively different from the previously demonstrated vetoing of scatter signals and opens a new path for improving the sensitivity of future GW detectors and other back-scatter limited devices. (paper)

  8. Ice cloud backscatter study and comparison with CALIPSO and MODIS satellite data. (United States)

    Ding, Jiachen; Yang, Ping; Holz, Robert E; Platnick, Steven; Meyer, Kerry G; Vaughan, Mark A; Hu, Yongxiang; King, Michael D


    An invariant imbedding T-matrix (II-TM) method is used to calculate the single-scattering properties of 8-column aggregate ice crystals. The II-TM based backscatter values are compared with those calculated by the improved geometric-optics method (IGOM) to refine the backscattering properties of the ice cloud radiative model used in the MODIS Collection 6 cloud optical property product. The integrated attenuated backscatter-to-cloud optical depth (IAB-ICOD) relation is derived from simulations using a CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) lidar simulator based on a Monte Carlo radiative transfer model. By comparing the simulation results and co-located CALIPSO and MODIS (Moderate Resolution Imaging Spectroradiometer) observations, the non-uniform zonal distribution of ice clouds over ocean is characterized in terms of a mixture of smooth and rough ice particles. The percentage of the smooth particles is approximately 6% and 9% for tropical and midlatitude ice clouds, respectively.

  9. The complementary use of electron backscatter diffraction and ion channelling imaging for the characterization of nanotwins

    DEFF Research Database (Denmark)

    Alimadadi, Hossein; da Silva Fanta, Alice Bastos; Pantleon, Karen


    On the example of electrodeposited nickel films, it is shown that unique information on twins with dimensions on the nanoscale can be obtained by suitable combination of ion channelling imaging and electron backscatter diffraction analysis, whereas both (routine) single techniques cannot meet...... the requirements for analysis of these films. High‐resolution electron backscatter diffraction is inadequate for full characterization of nanotwins, but image quality maps obtained from electron backscatter diffraction at least yield a qualitative estimation of the location and number of nanotwins. Complementing...... EBSD data based on ion channelling images are proposed. Thorough selection of the complementary techniques opens future perspectives for the investigation of other challenging samples with nanoscale features in the microstructure....

  10. Cavitation inception by the backscattering of pressure waves from a bubble interface

    Energy Technology Data Exchange (ETDEWEB)

    Takahira, Hiroyuki, E-mail:; Ogasawara, Toshiyuki, E-mail:; Mori, Naoto, E-mail:; Tanaka, Moe [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531 (Japan)


    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  11. Long Wavelength SAR Backscatter Modelling Trends as a Consequence of the Emergent Properties of Tree Populations

    Directory of Open Access Journals (Sweden)

    Matthew Brolly


    Full Text Available This study describes the novel use of a macroecological plant and forest structure model in conjunction with a Radiative Transfer (RT model to better understand interactions between microwaves and forest canopies. Trends predicted by the RT model, resulting from interactions with mixed age, mono and multi species forests, are analysed in comparison to those predicted using a simplistic structure based scattering model. This model relates backscatter to scatterer cross sectional or volume specifications, dependent on the size. The Spatially Explicit Reiterative Algorithm (SERA model is used to provide a widely varied tree size distribution while maintaining allometric consistency to produce a natural-like forest representation. The RT model is parameterised using structural information from SERA and microwave backscatter simulations are used to analyse the impact of changes to the forest stand. Results show that the slope of the saturation curve observed in the Synthetic Aperture Radar (SAR backscatter-biomass relationship is sensitive to thinning and therefore forest basal area. Due to similarities displayed between the results of the RT and simplistic model, it is determined that forest SAR backscatter behaviour at long microwave wavelengths may be described generally using equations related to total stem volume and basal area. The nature of these equations is such that they describe saturating behaviour of forests in the absence of attenuation in comparable fashion to the trends exhibited using the RT model. Both modelled backscatter trends predict a   relationship to forest basal area from an early age when forest volume is increasing. When this is not the case, it is assumed to be a result of attenuation of the dominant stem-ground interaction due to the presence of excessive numbers of stems. This work shows how forest growth models can be successfully incorporated into existing independent scattering models and reveals, through the RT

  12. Quantitative evaluation of myocardial fibrosis by cardiac integrated backscatter analysis in Kawasaki disease. (United States)

    Xie, Lijian; Wang, Renjian; Huang, Min; Zhang, Yongwei; Shen, Jie; Xiao, Tingting


    Kawasaki disease is an acute, systemic vasculitis that affects the coronary arteries. However, the relationship between myocardial fibrosis and Kawasaki disease has been completely unknown until now. We aimed to provide quantitative information about myocardial fibrosis using cardiac integrated backscatter in Han race Kawasaki disease patients. Ninety Kawasaki disease patients and 90 healthy control subjects were recruited. Based on Kawasaki disease status, the patients were categorized into 3 groups: acute, subacute, and convalescence phase. Based on coronary artery status, the Kawasaki disease patients were categorized into 3 groups: without coronary artery lesions, with coronary artery dilation, and with coronary artery aneurysms. All subjects underwent two-dimensional and Doppler examinations to measure clinical echocardiographic parameters. Myocardial fibrosis was detected with calibrated integrated backscatter imaging. Left ventricle systolic functions were normal in both the Kawasaki disease and control participants. The myocardial calibrated integrated backscatter values of the left ventricles of the acute (p Kawasaki disease patients were significantly greater than those of the healthy controls. The left ventricle myocardial calibrated integrated backscatter values were significantly smaller in the Kawasaki disease patients without coronary artery lesions than in the Kawasaki disease patients with coronary artery dilations and coronary artery aneurysms in different phases. The left ventricle myocardial calibrated integrated backscatter results were positively correlated with coronary artery status in the acute (r = 0.331, p Kawasaki disease. Our findings may suggest that myocardial fibrosis occurs during early episodes of Kawasaki disease given uncertainties that exist regarding correlations of calibrated integrated backscatter and myocardial fibrosis.

  13. Raman backscattering of circularly polarized electromagnetic waves propagating along a magnetic field

    International Nuclear Information System (INIS)

    Maraghechi, B.; Willett, J.e.


    The stimulated Raman backscattering of an intense electromagnetic wave propagating in the extraordinary mode along a uniform, static magnetic field is considered. The dispersion relation for a homogeneous magnetized plasma in the presence of the circularly polarized pump waves is developed in the cold-plasma approximation with the pump frequency above the plasma frequency. Formulas are derived for the threshold νsub(OT) of the parametric instability and for the growth rate γ of the backscattered extraordinary wave and Langmuir wave. The effects of the magnetic field parallel to the direction of propagation on νsub(0T) and γ are studied numerically. (author)

  14. [Impact of Light Polarization on the Measurement of Water Particulate Backscattering Coefficient]. (United States)

    Liu, Jia; Gong, Fang; He, Xian-qiang; Zhu, Qian-kun; Huang, Hai-qing


    Particulate backscattering coefficient is a main inherent optical properties (IOPs) of water, which is also a determining factor of ocean color and a basic parameter for inversion of satellite ocean color remote sensing. In-situ measurement with optical instruments is currently the main method for obtaining the particulate backscattering coefficient of water. Due to reflection and refraction by the mirrors in the instrument optical path, the emergent light source from the instrument may be partly polarized, thus to impact the measurement accuracy of water backscattering coefficient. At present, the light polarization of measuring instruments and its impact on the measurement accuracy of particulate backscattering coefficient are still poorly known. For this reason, taking a widely used backscattering coefficient measuring instrument HydroScat6 (HS-6) as an example in this paper, the polarization characteristic of the emergent light from the instrument was systematically measured, and further experimental study on the impact of the light polarization on the measurement accuracy of the particulate backscattering coefficient of water was carried out. The results show that the degree of polarization(DOP) of the central wavelength of emergent light ranges from 20% to 30% for all of the six channels of the HS-6, except the 590 nm channel from which the DOP of the emergent light is slightly low (-15%). Therefore, the emergent light from the HS-6 has significant polarization. Light polarization has non-neglectable impact on the measurement of particulate backscattering coefficient, and the impact degree varies with the wave band, linear polarization angle and suspended particulate matter (SPM) concentration. At different SPM concentrations, the mean difference caused by light polarization can reach 15.49%, 11.27%, 12.79%, 14.43%, 13.76%, and 12.46% in six bands, 420, 442, 470, 510, 590, and 670 nm, respectively. Consequently, the impact of light polarization on the

  15. [Backscattering Characteristics of Machining Surfaces and Retrieval of Surface Multi-Parameters]. (United States)

    Tao, Hui-rong; Zhang, Fu-min; Qu, Xing-hua


    For no cooperation target laser ranging, the backscattering properties of the long-range and real machined surfaces are uncertain which seriously affect the ranging accuracy. It is an important bottleneck restricting the development of no cooperation ranging technology. In this paper, the backscattering characteristics of three typical machining surfaces (vertidal milling processing method, horizontal milling processing method and plain grinding processing method) under the infrared laser irradiation with 1550 nm were measured. The relation between the surface nachining texture, incident azimuth, roughness and the backscattering distribution were analyzed and the reasons for different processing methods specific backscattering field formed were explored. The experimental results show that the distribution of backscattering spectra is greatly affected by the machined processing methods. Incident angle and roughness have regularity effect on the actual rough surface of each mode. To be able to get enough backscattering, knowing the surface texture direction and the roughness of machined metal is essential for the optimization of the non-contact measurement program in industry. On this basis, a method based on an artificial neural network (ANN) and genetic algorithm (GA), is proposed to retrieve the surface multi-parameters of the machined metal. The generalized regression neural network (GRNN) was investigated and used in this application for the backscattering modeling. A genetic algorithm was used to retrieve the multi-parameters of incident azimuth angle, roughness and processing methods of machined metal sur face. Another processing method of sample (planer processing method) was used to validate data. The final results demonstrated that the method presented was efficient in parameters retrieval tasks. This model can accurately distinguish processing methods and the relative error of incident azimuth and roughness is 1.21% and 1.03%, respectively. The inversion

  16. High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz

    International Nuclear Information System (INIS)

    Huang, Chih-Chung


    There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r 2 ) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm -1 at 30 MHz to 0.47 Nepers mm -1 at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was maximal around a

  17. Backscattered UV radiation - Effects of multiple scattering and the lower boundary of the atmosphere (United States)

    Aruga, T.; Heath, D. F.


    A method is proposed for the calculation of a multiple-scattering correction to the single-scattering calculation of the radiance of the terrestrial atmosphere resulting from backscattered ultraviolet solar radiation in the spectral region used in the ozone profile inversion. This method uses jointly the usual analytical and Monte Carlo methods. Effects of the lower boundary of the atmosphere, cloud tops, and ground surface are investigated both qualitatively and quantitatively. The ratio of multiple to single scattering is determined, and its importance in ozone profile inversion of backscattered UV solar radiation from the terrestrial atmosphere is evaluated. The polarization of the atmospheric radiance is treated briefly.

  18. Computation of Nonlinear Backscattering Using a High-Order Numerical Method (United States)

    Fibich, G.; Ilan, B.; Tsynkov, S.


    The nonlinear Schrodinger equation (NLS) is the standard model for propagation of intense laser beams in Kerr media. The NLS is derived from the nonlinear Helmholtz equation (NLH) by employing the paraxial approximation and neglecting the backscattered waves. In this study we use a fourth-order finite-difference method supplemented by special two-way artificial boundary conditions (ABCs) to solve the NLH as a boundary value problem. Our numerical methodology allows for a direct comparison of the NLH and NLS models and for an accurate quantitative assessment of the backscattered signal.

  19. Coherence loss in light backscattering by random media with nanoscale nonuniformities (United States)

    Brodsky, Anatol M.; Mitchell, Gordon T.; Ziegler, Summer L.; Burgess, Lloyd W.


    An experimental technique for measuring time-resolved coherence loss and destruction of backscattered wave packets in random media is described. The results of such measurements, performed with a modified Michelson interferometer, contain rich information about the characteristics of media nonuniformities. Experimental data for model nanosuspensions are compared with theoretical expressions developed in the paper which include the effects of Mie-type resonant scattering. We attribute one such observed effect to enhanced ineleastic optical transitions near the surface of nonmetallic nanoparticles. The inverse problem of characterization of multiscattering random media by backscattering is also considered.

  20. Coherence Loss in light backscattering by random media with nanoscale nonuniformities

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Anatol; Mitchell, Gordon T.; Ziegler, Summer L.; Burgess, Lloyd


    An experimental technique for measuring time-resolved coherence loss and destruction of backscattered wavepackets in random media is described. The results of such measurements, performed with a modified Michelson interferometer, contain rich information about the characteristics of media nonuniformities. Experimental data for model nanosuspensions are compared with theoretical expressions developed in the article which include the effects of Mie-type resonant scattering. One such observed effect is attributed to enhanced inelastic optical transitions near the surface of nonmetallic nanoparticles. The inverse problem of characterization of multiscattering random media by backscattering is considered.

  1. Assessing the contamination of SuperDARN global convection maps by non-F-region backscatter


    G. Chisham; G. Chisham; M. Pinnock; M. Pinnock


    Global convection mapping using line-of-sight Doppler velocity data from the Super Dual Auroral Radar Network (SuperDARN) is now an accepted method of imaging high-latitude ionospheric convection. This mapping process requires that the flow measured by the radars is defined solely by the convection electric field. This is generally only true of radar backscatter from the ionospheric F-region. We investigate the extent to which the E-region and ground backscatter in the SuperDARN data s...

  2. Jet-Tagged Back-Scattering Photons for Quark Gluon Plasma Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Rainer J. [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77845 (United States); De, Somnath; Srivastava, Dinesh K. [Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata – 700064 (India)


    Direct photons are important probes for quark gluon plasma created in high energy nuclear collisions. Various sources of direct photons in nuclear collisions are known, each of them endowed with characteristic information about the production process. However, it has been challenging to separate direct photon sources through measurements of single inclusive photon spectra and photon azimuthal asymmetry. Here we explore a method to identify photons created from the back-scattering of high momentum quarks off quark gluon plasma. We show that the correlation of back-scattering photons with a trigger jet leads to a signal that should be measurable at RHIC and LHC.

  3. The laser-backscattering equations and their application to the study of the atmospheric structure

    CERN Document Server

    Castrejon, R; Castrejon, J; Morales, A


    In this work a method for interpreting backscattering signals acquired by a lidar is described. The method is based on the elastic scattering of laser radiation due to gases and particles suspended in the atmosphere (bulk effects). We propose a space-time diagram which helps to evaluate the arguments of the equation that serves to calculate the lidar signal in terms of the backscattering coefficient. We describe how the system detects gradients on this coefficient, along the laser optical path. To illustrate the method, we present some typical lidar results obtained in the neighborhood of Mexico City. (Author)

  4. Experimental results and Monte Carlo simulations of a landmine localization device using the neutron backscattering method

    CERN Document Server

    Datema, C P; Eijk, C W E


    Experiments were carried out to investigate the possible use of neutron backscattering for the detection of landmines buried in the soil. Several landmines, buried in a sand-pit, were positively identified. A series of Monte Carlo simulations were performed to study the complexity of the neutron backscattering process and to optimize the geometry of a future prototype. The results of these simulations indicate that this method shows great potential for the detection of non-metallic landmines (with a plastic casing), for which so far no reliable method has been found.

  5. High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chih-Chung, E-mail: [Department of Electrical Engineering, Fu Jen Catholic University, Taipei, Taiwan (China)


    There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r{sup 2}) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm{sup -1} at 30 MHz to 0.47 Nepers mm{sup -1} at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was

  6. Differential absorption lidar CO2 laser system for remote sensing of TATP related gases. (United States)

    Pal, Avishekh; Clark, C Douglas; Sigman, Michael; Killinger, Dennis K


    A CW tunable 10.6 microm CO(2) laser differential absorption lidar (DIAL) system has been developed, for the first time to our knowledge, for the remote sensing of triacetone triperoxide (TATP) gas vapors, which have strong absorption lines at several wavelengths, including 3.3, 8.3, and 10.6 microm. The DIAL laser beam was transmitted through an enclosed absorption cell containing TATP or SF(6), and backscattered returns were measured from a retroreflector array target at ranges of 5-100 m. DIAL sensitivity for the detection of TATP was about 0.5 ng/microl [52 parts in 10(6)(ppm)] for a 0.3 m path.

  7. From point-wise stress data to a continuous description of the 3D crustal in situ stress state (United States)

    Heidbach, O.; Ziegler, M.; Reiter, K.; Hergert, T.


    The in situ stress is a key parameter for the safe and sustainable management of geo-reservoirs or storage of waste and energy in deep geological repositories. It is also an essential initial condition for thermo-hydro-mechanical (THM) models that investigate man-made induced processes e.g. seismicity due to fluid injection/extraction, reservoir depletion or storage of heat producing high-level radioactive waste. Without a reasonable assumption on the initial stress condition it is not possible to assess if a man-made process is pushing the system into a critical state or not. However, modelling the initial 3D stress state on reservoir scale is challenging since data are hardly available before drilling in the area of interest. This is in particular the case for the stress magnitude data which are a prerequisite for a reliable model calibration. Here, we present a multi-stage 3D geomechani­cal-numerical model approach to estimate for a reservoir-scale volume the 3D in situ stress state. First, we set up a large-scale model which is calibrated by stress data and use the modelled stress field subsequently to calibrate a small-scale model located within the large-scale model. The local model contains a significantly higher resolution representation of the subsurface geometry around boreholes of a projected geothermal power plant. This approach incorporates two models and is an alternative to the required trade-off between resolution, computational cost and calibration data which is inevitable for a single model; an extension to a three-stage approach would be straight forward. We exemplify the two-stage approach for the area around Munich in the German Molasse Basin. The results of the reservoir-scale model are presented in terms of values for slip tendency as a measure for the criticality of fault reactivation. The model results show that variations due to uncertainties in the input data are mainly introduced by the uncertain material properties and missing estimates for the magnitude of the maximum horizontal stress SHmax, needed for a more reliable model calibration. This leads to the conclusion that at this stage the model's reliability depends only on the amount and quality of input data records such as available stress information rather than on the modelling technique itself.

  8. Absorptive Capacity and Diversity

    DEFF Research Database (Denmark)

    Kristinsson, Kári

    international business, organizational economics, strategic management, technology management and last but not least neo-Schumpeterian economics. The goal of this dissertation is to examine what many consider as neglected arguments from the work by Cohen and Levinthal and thereby illuminate an otherwise......One of the most influential contributions to neo-Schumpeterian economics is Cohen and Levinthal‘s papers on absorptive capacity. Since their publication in the late 1980s and early 1990s the concept absorptive capacity has had substantial impact on research in economics and management, including...... overlooked area of research. Although research based on Cohen and Levinthal‘s work has made considerable impact, there is scarcity of research on certain fundamental points argued by Cohen and Levinthal. Among these is the importance of employee diversity as well as the type and nature of interaction between...

  9. Sound absorption of snow


    Maysenhölder, W.; Schneebeli, M.; Zhou, X.; Zhang, T.; Heggli, M.


    Recently fallen snow possesses good sound-absorbing properties. This fact is well-known and confirmed by measurements. Is the filigree structure of snowflakes decisive? In principle we know that the sound-absorbing capacity of a porous material is dependent on its structure. But until now the question as to which structural characteristics are significant has been insufficiently answered. Detailed investigations of snow are to explain this fact by precise measurements of the sound absorption,...

  10. Iron absorption studies

    International Nuclear Information System (INIS)

    Ekenved, G.


    The main objective of the present work was to study iron absorption from different iron preparations in different types of subjects and under varying therapeutic conditions. The studies were performed with different radioiron isotope techniques and with a serum iron technique. The preparations used were solutions of ferrous sulphate and rapidly-disintegrating tablets containing ferrous sulphate, ferrous fumarate and ferrous carbonate and a slow-release ferrous sulphate tablet of an insoluble matrix type (Duroferon Durules). The serum iron method was evaluated and good correlation was found between the serum iron response and the total amount of iron absorbed after an oral dose of iron given in solution or in tablet form. New technique for studying the in-vivo release properties of tablets was presented. Iron tablets labelled with a radio-isotope were given to healthy subjects. The decline of the radioactivity in the tablets was followed by a profile scanning technique applied to different types of iron tablets. The release of iron from the two types of tablets was shown to be slower in vivo than in vitro. It was found that co-administration of antacids and iron tablets led to a marked reduction in the iron absorption and that these drugs should not be administered sumultaneously. A standardized meal markedly decreased the absorbability of iron from iron tablets. The influence of the meal was more marked with rapidly-disintegrating than with slow-release ferrous sulphate tablets. The absorption from rapidly-disintegrating and slow-release ferrous sulphate tablets was compared under practical clinical conditions during an extended treatment period. The studies were performed in healthy subjects, blood donors and patients with iron deficiency anaemia and it was found that the absorption of iron from the slow-release tablets was significantly better than from the rapidly-disintegrating tablets in all three groups of subjects. (author)

  11. Total Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Rubio, B.; Gelletly, W.


    The problem of determining the distribution of beta decay strength (B(GT)) as a function of excitation energy in the daughter nucleus is discussed. Total Absorption Spectroscopy is shown to provide a way of determining the B(GT) precisely. A brief history of such measurements and a discussion of the advantages and disadvantages of this technique, is followed by examples of two recent studies using the technique. (authors)

  12. Relic Neutrino Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eberle, b


    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  13. Selection Algorithm for the CALIPSO Lidar Aerosol Extinction-to-Backscatter Ratio (United States)

    Omar, Ali H.; Winker, David M.; Vaughan, Mark A.


    The extinction-to-backscatter ratio (S(sub a)) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine Sa for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S(sub a) for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S(sub a) is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, delta, the layer integrated attenuated backscatter, beta, and the mean layer total attenuated color ratio, gamma, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S(sub a) value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

  14. Carbon/Hydrogen ratio determination in hydrocarbons and its mixtures by electron backscattering technique

    International Nuclear Information System (INIS)

    Padron, I.; Desdin, L.F.; Navarro, A.; Fuentes, M.


    A method carbon/hydrogen ratio (C/H) determination in hydrocarbons and its mixtures was improved using the electron backscattering technique. Besides the hetero atoms (S,O and N) influence in petroleum is studied for being able to determinate the C/H ratio in cuban petroleum with high sulphur contents

  15. A New Method for Parameterization of Phase Shift and Backscattering Amplitude

    NARCIS (Netherlands)

    Koningsberger, D.C.; Vaarkamp, M.; Linders, J.C.


    Parameterization of phase and backscattering amplitude with cubic splines is described. Using these cubic spline, the analytical partial derivatives of the plane wave EXAFS function can be calculated. The use of analytical partial derivatives decreases the CPU time needed for a refinement by over

  16. Analytic representation of the backscatter correction factor at the exit of high energy photon beams

    International Nuclear Information System (INIS)

    Kappas, K.; Rosenwald, J.C.


    In high-energy X-ray beams, the dose calculated near the exit surface under electronic equilibrium conditions is generally over-estimated since it is derived from measurements performed in water with large thickness of backscattering material. The resulting error depends on a number of parameters such as beam energy, field dimension, thickness of overlying and underlying material. The authors have systematically measured for 4 different energies and for different para- meters and for different combinations of the above parameters, the reduction of dose due to backscatter. This correction is expressed as a multiplicative factor, called 'Backscatter Correction Factor' (BCF). This BCF is larger for lower energies, larger field sizes and larger depths. The BCF has been represented by an analytical expression which involves an exponential function of the backscattering thickness and linear relationships with depth field size and beam quality index. Using this expression, the BCF can be calculated within 0.5% for any conditions in the energy range investigated. (author). 14 refs.; 4 figs.; 3 tabs

  17. Calibrated integrated backscatter and myocardial fibrosis in patients undergoing cardiac surgery

    NARCIS (Netherlands)

    Prior, David L; Somaratne, Jithendra B; Jenkins, Alicia J; Yii, Michael; Newcomb, Andrew E; Schalkwijk, Casper G; Black, Mary J; Kelly, Darren J; Campbell, Duncan J


    OBJECTIVE: The reported association between calibrated integrated backscatter (cIB) and myocardial fibrosis is based on study of patients with dilated or hypertrophic cardiomyopathy and extensive (mean 15-34%) fibrosis. Its association with lesser degrees of fibrosis is unknown. We examined the

  18. Super-resolved time-frequency analysis of wideband backscattered data

    DEFF Research Database (Denmark)

    Moore, John; Ling, H.


    A time-frequency super-resolution procedure is presented for processing wideband backscattered data containing both scattering center and natural resonance information. In this procedure, Prony's method is first applied in the frequency domain to locate scattering centers. The data is processed o...

  19. Sensitivity of Multi-Source SAR Backscatter to Changes in Forest Aboveground Biomass

    Directory of Open Access Journals (Sweden)

    Wenli Huang


    Full Text Available Accurate estimates of forest aboveground biomass (AGB after anthropogenic disturbance could reduce uncertainties in the carbon budget of terrestrial ecosystems and provide critical information to policy makers. Yet, the loss of carbon due to forest disturbance and the gain from post-disturbance recovery have not been sufficiently assessed. In this study, a sensitivity analysis was first conducted to investigate: (1 the influence of incidence angle and soil moisture on Synthetic Aperture Radar (SAR backscatter; (2 the feasibility of cross-image normalization between multi-temporal and multi-sensor SAR data; and (3 the possibility of applying normalized backscatter data to detect forest biomass changes. An empirical model was used to reduce incidence angle effects, followed by cross-image normalization procedure to lessen soil moisture effect. Changes in forest biomass at medium spatial resolution (100 m were mapped using both spaceborne and airborne SAR data. Results indicate that (1 the effect of incidence angle on SAR backscatter could be reduced to less than 1 dB by the correction model for airborne SAR data; (2 over 50% of the changes in SAR backscatter due to soil moisture could be eliminated by the cross-image normalization procedure; and (3 forest biomass changes greater than 100 Mg·ha−1 or above 50% of 150 Mg·ha−1 are detectable using cross-normalized SAR data.

  20. Aerosol extinction-to-backscatter ratio derived from passive satellite measurements

    Directory of Open Access Journals (Sweden)

    F.-M. Bréon


    Full Text Available Spaceborne reflectance measurements from the POLDER instrument are used to study the specific directional signature close to the backscatter direction. The data analysis makes it possible to derive the extinction-to-backscatter ratio (EBR, which is related to the inverse of the scattering phase function for an angle of 180° and is needed for a quantitative interpretation of lidar observations (active measurements. In addition, the multidirectional measurements are used to quantify the scattering phase function variations close to backscatter, which also provide some indication of the aerosol particle size and shape. The spatial distributions of both parameters show consistent patterns that are consistent with the aerosol type distributions. Pollution aerosols have an EBR close to 70, desert dust values are on the order of 50 and EBR of marine aerosols is close to 25. The scattering phase function shows an increase with the scattering angle close to backscatter. The relative increase ∂lnP/∂γ is close to 0.01 for dust and pollution type aerosols and 0.06 for marine type aerosols. These values are consistent with those retrieved from Mie simulations.

  1. Contribution of back-scattered electromagnetic rays to the Moessbauer conversion electron spectrum

    International Nuclear Information System (INIS)

    Ruskov, T.; Ruskov, R.; Paneva, D.; Lefterov, D.


    The contribution of back-scattered electromagnetic rays in a 57 Fe conversion electron Moessbauer spectrum is considered using proportional counter as a detector. A simplified method for measuring this contribution is described. The experimental results show that this contribution strongly depends on the construction of the counter and the selected fraction in the pulse-height spectrum

  2. Model for hydrogen isotope backscattering, trapping and depth profiles in C and a-Si

    International Nuclear Information System (INIS)

    Cohen, S.A.; McCracken, G.M.


    A model of low energy hydrogen trapping and backscattering in carbon and a-silicon is described. Depth profiles are calculated and numerical results presented for various incident angular and energy distributions. The calculations yield a relation between depth profiles and the incident ion energy distribution. The use of this model for tokamak plasma diagnosis is discussed

  3. Lidar monitoring of regions of intense backscatter with poorly defined boundaries (United States)

    Vladimir A. Kovalev; Alexander Petkov; Cyle Wold; WeiMin Hao


    The upper height of a region of intense backscatter with a poorly defined boundary between this region and a region of clear air above it is found as the maximal height where aerosol heterogeneity is detectable, that is, where it can be discriminated from noise. The theoretical basis behind the retrieval technique and the corresponding lidar-data-processing procedures...

  4. Dominant Channel Occupancy for Wi-Fi Backscatter Uplink in Industrial Internet of Things

    Directory of Open Access Journals (Sweden)

    Jung-Hyok Kwon


    Full Text Available This paper presents a dominant channel occupancy (DCO mechanism for the Wi-Fi backscatter uplink in the industrial Internet of things (IIoT. The DCO provides high-priority channel access and reliable burst transmission to the Wi-Fi backscatter devices, thereby enabling the Wi-Fi backscatter tag to deliver its tag information to the Wi-Fi reader without interference from neighboring legacy Wi-Fi devices to guarantee the timeliness and reliability of the IIoT system. For the former, we consider three types of medium access control (MAC configurations: “carrier sense multiple access with collision avoidance (CSMA/CA starting with short inter-frame space (SIFS”, “freezing of the backoff period”, and “reduced CWmin.” In addition, the DCO uses the SIFS between burst packets to guarantee reliable burst transmission. To verify the effectiveness of DCO and determine a proper value for MAC parameters, we conduct experimental simulations under IEEE 802.11n PHY/MAC environments. The simulation results show that the reduced CWmin has the most significant effect on the channel occupancy. The Wi-Fi backscatter devices achieve much higher throughput than the separate cases when two or more configurations are used simultaneously. Moreover, the results exhibit that the use of SIFS between consecutive packets supports reliable burst transmission regardless of the transmission of the legacy Wi-Fi devices in the vicinity.

  5. Backscattering spectroscopy developments for the University of Oxford Scanning External Proton Milliprobe (SEPM) (United States)

    Jarjis, R. A.


    An external beam facility has recently been developed at the University of Oxford with the aim of carrying out non-sampling material characterisations on objects which are kept at atmospheric pressure using magnetically focused scanning beam of protons. This publication deals with one part of the developments, which is the application of backscattering spectroscopy in both operational diagnosis and the analysis of solids and gases. Results are reported for tests using an experimental external beam nozzle incorporating a window for extracting the proton beam from the vacuum to a helium gas flushed external chamber housing a Si(Li) detector and a semi-conductor charged-particle detector. The latter is used in the backscattering analysis of objects whilst a second charged-particle detector is also incorporated under vacuum in order to monitor backscattering signals originating from the window and the gas present in the vicinity of the analysis volume. The aim of the development is to create controlled conditions for comprehensive analysis using both PIXE and RBS. Two new backscattering techniques are reported in this publication: (a) External Beam Multi-Dimensional Analysis (EBMA) and (b) Resonant Scattering Multi-Dimensional Analysis (RSMA). In addition, we report on the findings of an initial study of using EBMA to assess gold layer application in Japanese porcelain and Islamic manuscripts, and using RSMA in investigating gas dynamics.

  6. Estimate of the Incoherent-Scattering Contribution to Lidar Backscatter from Clouds

    NARCIS (Netherlands)

    De Wolf, D.A.; Russchenberg, W.J.; Ligthart, L.P.


    Lidar backscatter from clouds in the Delft University of Technology experiment is complicated by the fact that the transmitter has a narrow beam width, whereas the receiver has a much wider one. The issue here is whether reception of light scattered incoherently by cloud particles can contribute

  7. The effect of backscattering on the beta dose absorbed by individual quartz grains

    DEFF Research Database (Denmark)

    Autzen, Martin; Guérin, G.; Murray, A. S.


    We describe the effect on dose rates and over-dispersion (OD) of changing the spectrum of energies to which grains of various shapes and volumes are exposed during beta irradiation, either by changing the backscattering medium or attenuating the incident spectrum. Dose rates are found to increase...

  8. X-ray backscatter radiography. Intrusive instead of penetrating, X-ray shadow phenomenon

    International Nuclear Information System (INIS)

    Wrobel, Norma; Kolkoori, Sanjeevareddy; Osterloh, Kurt; European Federation for Non-Destructive Testing


    Generally, the primary practical advantage of X-ray backscattering radiography is that there is no need to place a detector on the side of the specimen opposite to the source. Such a situation usually is encountered whenever the specimen is not only standing right in front of a wall or even inside a wall but also if the specimen is such big that radiography is not possible because of the layer thickness to be penetrated. The method used here differs fundamentally from the conventional method to interrogate the object with a scanning beam ('pencil beam') and to collect the whole backscattered radiation from the area. The object is fully illuminated by a (uncollimated) cone beam. Here, the image is recorded with a camera of absorbent material (tungsten, lead), which contains a matrix detector as the image receiver. The optical effect is generated by a special twisted slit collimator which operates according to an extended pinhole camera. The independent positioning of source and camera allows a variable irradiation geometry which causes different images as a result. As a consequence, a complex object in front of a backscattering wall appears completely different than standing alone. So X-ray backscatter images have to be interpreted according to their illumination with X-rays and their surroundings. (orig.)

  9. Designing scheme of a γ-ray ICT system using compton back-scattering

    International Nuclear Information System (INIS)

    Xiao Jianmin


    The designing scheme of a γ ray ICT system by using Compton back-scattering is put forward. The technical norms, detector system, γ radioactive source, mechanical scanning equipment, and data acquisition and image reconstruction principle of this ICT are described

  10. Characterizing Indian Ocean manganese nodule-bearing seafloor using multi-beam angular backscatter

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Kodagali, V.N.

    and sediment volume roughness parameters. The application of a composite roughness model to a nodule-bearing region (6,600 km2) of the CIOB, to determine seafloor interface roughness parameters from a multi-beam backscatter dataset, shows only four power law...

  11. Observation of enhanced infrared absorption in silicon supersaturated with gold by pulsed laser melting of nanometer-thick gold films (United States)

    Chow, Philippe K.; Yang, Wenjie; Hudspeth, Quentin; Lim, Shao Qi; Williams, Jim S.; Warrender, Jeffrey M.


    We demonstrate that pulsed laser melting (PLM) of thin 1, 5, and 10 nm-thick vapor-deposited gold layers on silicon enhances its room-temperature sub-band gap infrared absorption, as in the case of ion-implanted and PLM-treated silicon. The former approach offers reduced fabrication complexity and avoids implantation-induced lattice damage compared to ion implantation and pulsed laser melting, while exhibiting comparable optical absorptance. We additionally observed strong broadband absorptance enhancement in PLM samples made using 5- and 10-nm-thick gold layers. Raman spectroscopy and Rutherford backscattering analysis indicate that such an enhancement could be explained by absorption by a metastable, disordered and gold-rich surface layer. The sheet resistance and the diode electrical characteristics further elucidate the role of gold-supersaturation in silicon, revealing the promise for future silicon-based infrared device applications.

  12. A Model for Backscattering from Quasi Periodic Corn Canopies at L-Band (United States)

    Lang, R.; Utku, C.; Zhao, Q.; O'Neill, P.


    In this study, a model for backscattering at L-band from a corn canopy is proposed. The canopy consists of a quasi-periodic distribution of stalks and a random distribution of leaves. The Distorted Born Approximation (DBA) is employed to calculate the single scattered return from the corn field. The new feature of the method is that the coherence of the stalks in the row direction is incorporated in the model in a systematic fashion. Since the wavelength is on the order of the distance between corn stalks in a row, grating lobe behavior is observed at certain azimuth angles of incidence. The results are compared with experimental values measured in Huntsville, Alabama in 1998. The mean field and the effective dielectric constant of the canopy are obtained by using the Foldy approximation. The stalks are placed in the effective medium in a two dimensional lattice to simulate the row structure of a corn field. In order to mimic a real corn field, a quasi-periodic stalk distribution is assumed where the stalks are given small random perturbations about their lattice locations. Corn leaves are also embedded in the effective medium and the backscattered field from the stalks and the leaves is computed. The backscattering coefficient is calculated and averaged over successive stalk position perturbations. It is assumed that soil erosion has smoothed the soil sufficiently so that it can be assumed flat. Corn field backscatter data was collected from cornfields during the Huntsville 98 experimental campaign held at Alabama A&M University Research Station, Huntsville, Alabama in 1998 using the NASA/GW truck mounted radar. Extensive ground truth data was collected. This included soil moisture measurements and corn plant architectural data to be used in the model. In particular, the distances between the stalks in a single row have been measured. The L-band radar backscatter data was collected for both H and V polarizations and for look angles of 15o and 45o over a two week

  13. Evaluation of backscatter dose from internal lead shielding in clinical electron beams using EGSnrc Monte Carlo simulations. (United States)

    De Vries, Rowen J; Marsh, Steven


    Internal lead shielding is utilized during superficial electron beam treatments of the head and neck, such as lip carcinoma. Methods for predicting backscattered dose include the use of empirical equations or performing physical measurements. The accuracy of these empirical equations required verification for the local electron beams. In this study, a Monte Carlo model of a Siemens Artiste linac was developed for 6, 9, 12, and 15 MeV electron beams using the EGSnrc MC package. The model was verified against physical measurements to an accuracy of better than 2% and 2mm. Multiple MC simulations of lead interfaces at different depths, corresponding to mean electron energies in the range of 0.2-14 MeV at the interfaces, were performed to calculate electron backscatter values. The simulated electron backscatter was compared with current empirical equations to ascertain their accuracy. The major finding was that the current set of backscatter equations does not accurately predict electron backscatter, particularly in the lower energies region. A new equation was derived which enables estimation of electron backscatter factor at any depth upstream from the interface for the local treatment machines. The derived equation agreed to within 1.5% of the MC simulated electron backscatter at the lead interface and upstream positions. Verification of the equation was performed by comparing to measurements of the electron backscatter factor using Gafchromic EBT2 film. These results show a mean value of 0.997 ± 0.022 to 1σ of the predicted values of electron backscatter. The new empirical equation presented can accurately estimate electron backscatter factor from lead shielding in the range of 0.2 to 14 MeV for the local linacs.

  14. Effects of Snow/ Soil Interface on Microwave Backscatter of Terrestrial Snowpack at X- and Ku- Band (United States)

    Kang, D. H.; Tan, S.; Zhu, J.; Gu, W.; Tsang, L.; Kim, E. J.


    Recent advances in monitoring and modeling capabilities to support remote sensing of terrestrial snow is encouraging to develop satellite mission concept in monitoring cold-region hydrological processes on global scales. However, it is still challenging to link back the active microwave backscattering signals to physical snowpack parameters. One of the limitations resides in the ignorance of the vegetation and soil conditions beneath the snowpack in the microwave scattering/ emission modeling and the snow water equivalent (SWE) retrieval algorithm. During the SnowEx 2017 winter campaign in Grand Mesa, CO, a particular effort has been made on comprehensive measurements of the underlying vegetation and soil characteristics from the snowpit measurements. Besides conducting standard snow core sampling, we have made additional protocols to record the background information beneath the snowpack. Recent works on active SWE retrieval algorithm using backscatters at X- (9.6 GHz) and Ku- (17.2 GHz) band suggest the significant signals from the background scattering characterization. The background scattering arising from the rough snow/ soil interface and the buried vegetation inside and beneath the snowpack modifies the sensitivity of the total backscatter to SWE. In this paper, we summarize the snow/ soil interface conditions as observed in the SnowEx campaign. We also develop standards for future in-situ snowpit measurements to include regular snow/ soil interface observations to accommodate the interpretation of microwave backscatter both for modeling and observation of microwave signatures. These observations first provide inputs to the microwave scattering models to predict the backscattering contribution from background, which is one of the key factors to be included to improve the SWE retrieval performance.


    Directory of Open Access Journals (Sweden)

    S. Chauhan


    Full Text Available The prime aim of this study was to assess the potential of semi-empirical water cloud model (WCM in simulating hybrid-polarized SAR backscatter signatures (RH and RV retrieved from RISAT-1 data and integrate the results into a graphical user interface (GUI to facilitate easy comprehension and interpretation. A predominant agricultural wheat growing area was selected in Mathura and Bharatpur districts located in the Indian states of Uttar Pradesh and Rajasthan respectively to carry out the study. The three-date datasets were acquired covering the crucial growth stages of the wheat crop. In synchrony, the fieldwork was organized to measure crop/soil parameters. The RH and RV backscattering coefficient images were extracted from the SAR data for all the three dates. The effect of four combinations of vegetation descriptors (V1 and V2 viz., LAI-LAI, LAI-Plant water content (PWC, Leaf water area index (LWAI-LWAI, and LAI-Interaction factor (IF on the total RH and RV backscatter was analyzed. The results revealed that WCM calibrated with LAI and IF as the two vegetation descriptors simulated the total RH and RV backscatter values with highest R2 of 0.90 and 0.85 while the RMSE was lowest among the other tested models (1.18 and 1.25 dB, respectively. The theoretical considerations and interpretations have been discussed and examined in the paper. The novelty of this work emanates from the fact that it is a first step towards the modeling of hybrid-polarized backscatter data using an accurately parameterized semi-empirical approach.

  16. Variations in daily quality assurance dosimetry from device levelling, feet position and backscatter material

    International Nuclear Information System (INIS)

    Ceylan, Abdurrahman; Cullen, Ashley; Butson, Martin; Yu, Peter K.N.; Alnawaf, Hani


    Daily quality assurance procedures are an essential part of radiotherapy medical physics. Devices such as the Sun Nuclear, DQA3 are effective tools for analysis of daily dosimetry including flatness, symmetry, energy, field size and central axis radiation dose measurement. The DQA3 can be used on the treatment couch of the linear accelerator or on a dedicated table/bed for superficial and orthovoltage x-ray machines. This device is levelled using its dedicated feet. This work has shown that depending on the quantity of backscatter material behind the DQA3 device, the position of the levelling feet can affect the measured central axis dose by up to 1.8 % (250 kVp and 6 MV) and that the introduction of more backscatter material behind the DQA3 can lead to up to 7.2 % (6 MV) variations in measured central axis dose. In conditions where no backscatter material is present, dose measurements can vary up to 1 %. As such this work has highlighted the need to keep the material behind the DQA3 device constant as well as maintaining the accuracy of the feet position on the device to effectively measure the most accurate daily constancy achievable. Results have also shown that variations in symmetry and energy calculations of up to 1 % can occur if the device is not levelled appropriately. As such, we recommend the position of the levelling feet on the device be as close as possible to the device so that a constant distance is kept between the DQA3 and the treatment couch and thus minimal levelling variations also occur. We would also recommend having no extra backscattering material behind the DQA3 device during use to minimise any variations which might occur from these backscattering effects.

  17. Statistical modelling of the backscattered field in a one-dimensional non-stationary stochastic problem (United States)

    Gulin, O. E.; Yaroshchuk, I. O.


    Within the framework of an exact wave approach in the spatial-time domain, the one-dimensional stochastic problem of sound pulse scattering by a layered random medium is considered. On the basis of a unification of methods which has been developed by the authors, previously applied to the investigation of non-stationary deterministic wave problems and stochastic stationary wave problems, an analytical-numerical simulation of the behaviour of the backscattered field stochastic characteristics was carried out. Several forms of incident pulses and signals are analysed. We assume that random fluctuations of a medium are described by virtue of the Gaussian Markov process with an exponential correlation function. The most important parameters appearing in the problem are discussed; namely, the time scales of diffusion, pulse durations, the medium layer thickness or the largest observation time scale in comparison with the time scale of one correlation length for the case of a half-space. An exact pattern of the pulse backscattering processes is obtained. It is illustrated by the behaviour of the backscattered field statistical moments for all observation times which are of interest. It is shown that during the time interval when the main part of the pulse energy leaves the medium, the backscattered field is a substantially non-stationary process, having a non-zero mean value and an average intensity that decays according to a power law. There are various power indices for the different duration incident pulses, however, they are not the same as those of previous papers, which were obtained on the basis of an approximate and asymptotic analysis. We have also verified that the Gaussian law is valid for the probability density function of the backscattered field in the case of any incident pulse duration.

  18. Absorption heat pumps (United States)

    Huhtinen, M.; Heikkilae, M.; Andersson, R.


    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  19. Rapidly variable relatvistic absorption (United States)

    Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.


    I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

  20. Geospatial Absorption and Regional Effects

    Directory of Open Access Journals (Sweden)



    Full Text Available The geospatial absorptions are characterized by a specific complexity both in content and in their phenomenological and spatial manifestation fields. Such processes are differentiated according to their specificity to pre-absorption, absorption or post-absorption. The mechanisms that contribute to absorption are extremely numerous: aggregation, extension, diffusion, substitution, resistivity (resilience, stratification, borrowings, etc. Between these mechanisms frequent relations are established determining an amplification of the process and of its regional effects. The installation of the geographic osmosis phenomenon in a given territory (a place for example leads to a homogenization of the geospatial state and to the installation of the regional homogeneity.

  1. Improved detection and mapping of deepwater hydrocarbon seeps: optimizing multibeam echosounder seafloor backscatter acquisition and processing techniques (United States)

    Mitchell, Garrett A.; Orange, Daniel L.; Gharib, Jamshid J.; Kennedy, Paul


    Marine seep hunting surveys are a current focus of hydrocarbon exploration surveys due to recent advances in offshore geophysical surveying, geochemical sampling, and analytical technologies. Hydrocarbon seeps are ephemeral, small, discrete, and therefore difficult to sample on the deep seafloor. Multibeam echosounders are an efficient seafloor exploration tool to remotely locate and map seep features. Geophysical signatures from hydrocarbon seeps are acoustically-evident in bathymetric, seafloor backscatter, midwater backscatter datasets. Interpretation of these signatures in backscatter datasets is a fundamental component of commercial seep hunting campaigns. Degradation of backscatter datasets resulting from environmental, geometric, and system noise can interfere with the detection and delineation of seeps. We present a relative backscatter intensity normalization method and an oversampling acquisition technique that can improve the geological resolvability of hydrocarbon seeps. We use Green Canyon (GC) Block 600 in the Northern Gulf of Mexico as a seep calibration site for a Kongsberg EM302 30 kHz MBES prior to the start of the Gigante seep hunting program to analyze these techniques. At GC600, we evaluate the results of a backscatter intensity normalization, assess the effectiveness of 2X seafloor coverage in resolving seep-related features in backscatter data, and determine the off-nadir detection limits of bubble plumes using the EM302. Incorporating these techniques into seep hunting surveys can improve the detectability and sampling of seafloor seeps.

  2. Novel X-ray backscatter technique for detection of dangerous materials: application to aviation and port security

    International Nuclear Information System (INIS)

    Kolkoori, S; Wrobel, N; Osterloh, K; Zscherpel, U; Ewert, U


    Radiological inspections, in general, are the nondestructive testing (NDT) methods to detect the bulk of explosives in large objects. In contrast to personal luggage, cargo or building components constitute a complexity that may significantly hinder the detection of a threat by conventional X-ray transmission radiography. In this article, a novel X-ray backscatter technique is presented for detecting suspicious objects in a densely packed large object with only a single sided access. It consists of an X-ray backscatter camera with a special twisted slit collimator for imaging backscattering objects. The new X-ray backscatter camera is not only imaging the objects based on their densities but also by including the influences of surrounding objects. This unique feature of the X-ray backscatter camera provides new insights in identifying the internal features of the inspected object. Experimental mock-ups were designed imitating containers with threats among a complex packing as they may be encountered in reality. We investigated the dependence of the quality of the X-ray backscatter image on (a) the exposure time, (b) multiple exposures, (c) the distance between object and slit camera, and (d) the width of the slit. At the end, the significant advantages of the presented X-ray backscatter camera in the context of aviation and port security are discussed

  3. Novel X-ray backscatter technique for detection of dangerous materials: application to aviation and port security (United States)

    Kolkoori, S.; Wrobel, N.; Osterloh, K.; Zscherpel, U.; Ewert, U.


    Radiological inspections, in general, are the nondestructive testing (NDT) methods to detect the bulk of explosives in large objects. In contrast to personal luggage, cargo or building components constitute a complexity that may significantly hinder the detection of a threat by conventional X-ray transmission radiography. In this article, a novel X-ray backscatter technique is presented for detecting suspicious objects in a densely packed large object with only a single sided access. It consists of an X-ray backscatter camera with a special twisted slit collimator for imaging backscattering objects. The new X-ray backscatter camera is not only imaging the objects based on their densities but also by including the influences of surrounding objects. This unique feature of the X-ray backscatter camera provides new insights in identifying the internal features of the inspected object. Experimental mock-ups were designed imitating containers with threats among a complex packing as they may be encountered in reality. We investigated the dependence of the quality of the X-ray backscatter image on (a) the exposure time, (b) multiple exposures, (c) the distance between object and slit camera, and (d) the width of the slit. At the end, the significant advantages of the presented X-ray backscatter camera in the context of aviation and port security are discussed.

  4. Effects of cell spatial organization and size distribution on ultrasound backscattering. (United States)

    Saha, Ratan K; Kolios, Michael C


    In ultrasound tissue characterization dealing with cellular aggregates (such as tumors), it can be hypothesized that cell microstructure and spatial distribution dominate the backscatter signal. Effects of spatial organization and size distribution of nuclei in cell aggregates on ultrasound backscatter are examined in this work using 2-D computer simulations. The nuclei embedded in cytoplasm were assumed to be weak scatterers of incident ultrasound waves, and therefore multiple scattering could be neglected. The fluid sphere model was employed to obtain the scattering amplitude for each nucleus and the backscatter echo was generated by summing scattered signals originating from many nuclei. A Monte Carlo algorithm was implemented to generate realizations of cell aggregates. It was found that the integrated backscattering coefficient (IBSC) computed between 10 and 30 MHz increased by about 27 dB for a spatially random distribution of mono-disperse nuclei (radius = 4.5 μm) compared with that of a sample of periodically positioned mono-disperse nuclei. The IBSC also increased by nearly 7 dB (between 10 and 30 MHz) for a spatially random distribution of poly-disperse nuclei (mean radius ± SD = 4.5 ± 1.54 μm) compared with that of a spatially random distribution of mono-disperse nuclei. Two different Gaussian pulses with center frequencies 5 and 25 MHz were employed to study the backscatter envelope statistics. An 80% bandwidth was chosen for each case with approximately 0.32 mm as the full-width at half-maximum (FWHM) for the first pulse and 0.06 mm for the second. The incident beam was approximated as a Gaussian beam (FWHM = 2.11 and 1.05 mm for those pulses, respectively). The backscatter signal envelope histograms generally followed the Rayleigh distribution for mono-disperse and poly-disperse samples. However, for samples with partially ordered nuclei, if the irradiating pulse contained a frequency for which ultrasound wavelength and scatter periodicity became


    The absorption spectrum of MnF2 at 4.2K in the 3900A region was measured in zero external fields and in high fields. Exciton lines with magnon ...sidebands are observed, accompanied by a large number of weak satellite lines. Results on the exciton and magnon absorptions are similar to those of...McClure et al. The satellite lines are interpreted as being multi- magnon absorptions, and it is possible to fit the energy of all the absorptions with

  6. Problems during the determination of grain-sizes in austenitic plates by the application of ultrasonic-backscattering

    International Nuclear Information System (INIS)

    Hecht, A.; Neumann, E.; Mundry, E.; Thiel, R.


    Ultrasonic backscattering makes possible the nondestructive determination of grain size in austenitic strips. In immersion technique a short pulse is sent into the material and the backscattered sound-amplitude is measured. When using a calibration curve, grain sizes can be calculated from the backscattered sound-amplitudes. There are problems in practical use because of mechanical and electronical data having an influence on the results of measurement. An exact determination of grain size depends on accurate mechanical adjustment and on stability of the electronical equipment, too. (orig.) [de

  7. Analyzing Water's Optical Absorption (United States)


    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  8. Atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Haswell, S.J.


    Atomic absorption spectroscopy is now well established and widely used technique for the determination of trace and major elements in a wide range analyte types. There have been many advances in the atomic spectroscopy over the last decade and for this reason and to meet the demand, it was felt that there was a need for an updated book. Whilst interest in instrumental design has tended to dominate the minds of the spectrocopist, the analyst concerned with obtaining reliable and representative data, in diverse areas of application, has been diligently modifying and developing sample treatment and instrumental introduction techniques. Such methodology is de fundamental part of analysis and form the basis of the fourteen application chapters of this book. The text focuses in the main on AAS; however, the sample handling techniques described are in many cases equally applicable to ICP-OES and ICP-MS analysis. (author). refs.; figs.; tabs

  9. Water vapor differential absorption lidar development and evaluation (United States)

    Browell, E. V.; Wilkerson, T. D.; Mcllrath, T. J.


    A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements

  10. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    Energy Technology Data Exchange (ETDEWEB)

    Abedin, Ahmad Firdaus Zainal, E-mail:; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert [Department of Defence Science, Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi, Kuala Lumpur 57000 (Malaysia)


    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines.

  11. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    International Nuclear Information System (INIS)

    Abedin, Ahmad Firdaus Zainal; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert


    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines

  12. Nonlinear effects in collective absorption

    International Nuclear Information System (INIS)

    Uenoyama, Takeshi; Mima, Kunioki; Watanabe, Tsuguhiro.


    The collective absorption of high intensity laser radiation is analyzed numerically. Density profile modification due to the ponderomotive force associating laser radiation and the excited electron plasma waves is self-consistently taken into account, and the intensity dependences of the absorption efficiency are obtained. In the high intensity regime, the absorption efficiency is found to be strongly enhanced in the plasma without flow, but reduced with supersonic flow. (author)

  13. Atomic absorption spectrophotometry in perspective

    International Nuclear Information System (INIS)

    Soffiantini, V.


    Atomic absorption spectrophotometry is essentially an analytical technique used for quantitative trace metal analysis in a variety of materials. The speed and specificity of the technique is its greatest advantage over other analytical techniques. What atomic absorption spectrophotometry can and cannot do and its advantages and disadvantages are discussed, a summary of operating instructions are given, as well as a summary of analytical interferences. The applications of atomic absorption spectrophotometry are also shortly discussed

  14. Multi-wavelength profiles of aerosol backscatter over Lauder, New Zealand, 24 November 1992 (United States)

    McKenzie, R. L.; Rosen, J. M.; Kjome, N. T.; McGee, T. J.; Gross, M. R.; Singh, U. N.; Ferrare, R. F.; Kimvilakani, P.; Uchino, O.; Nagai, T.


    Simultaneous profiles of aerosol backscatter ratio were measured over Lauder, New Zealand (45 deg S, 170 deg E) on the night of November 24, 1992. Instrumentation comprised two complementary lidar systems and a backscattersonde, to give measurements at wavelengths 351, 490, 532, and 940 nm. The data from the lidars and the backscattersonde were self-consistent, enabling the wavelength dependence of aerosol backscatter to be determined as a function of altitude. This wavelength-dependence is a useful parameter in radiative transfer calculations. In the stratosphere, the average wavelength exponent between 351 and 940 nm was -1.23 +/- 0.1, which was in good agreement with values derived from measured physical properties of aerosols.

  15. Coherent backscattering and forward-scattering peaks in the quantum kicked rotor (United States)

    Lemarié, G.; Müller, Cord A.; Guéry-Odelin, D.; Miniatura, C.


    We propose and analyze an experimental scheme using the quantum kicked rotor to observe the newly predicted coherent forward-scattering peak together with its long-known twin brother, the coherent backscattering peak. Contrary to coherent backscattering, which arises already under weak-localization conditions, coherent forward scattering is only triggered by Anderson or strong localization. So far, coherent forward scattering has not been observed in conservative systems with elastic scattering by spatial disorder. We propose to turn to the quantum kicked rotor, which has a long and successful history as an accurate experimental platform to observe dynamical localization, i.e., Anderson localization in momentum space. We analyze the coherent forward-scattering effect for the quantum kicked rotor by extensive numerical simulations, both in the orthogonal and unitary class of disordered quantum systems, and show that an experimental realization involving phase-space rotation techniques is within reach of state-of-the-art cold-atom experiments.

  16. Effect of moisture on the accuracy of coke-ash determination by X-ray backscattering

    International Nuclear Information System (INIS)

    Pandey, H.D.; Prasad, M.S.


    Effect of moisture on the rapid non-destructive estimation of ash content in coal specimens using the X-ray backscattering technique has been studied extensively by various workers. In the present work, an attempt has been made to estimate its influence when the technique is extended to coke-ash determinations. From the study of the variation of backscattered intensity with change in the moisture content of a coke specimen, it is observed that the ash content varies significantly at moisture levels higher than 5%. The variation, however, remains within allowable limits if the moisture level is kept below 5%. This observation is confirmed by the actual measurement of ash percentages in thirteen coke specimens containing three different states of moisture levels viz. (i) in the dry state, (ii) with 5% moisture and (iii) with 10% moisture. (author)

  17. Method and apparatus for measuring incombustible content of coal mine dust using gamma-ray backscatter

    International Nuclear Information System (INIS)

    Armstrong, F.E.


    A method and apparatus for measuring incombustible content of particulate material, particularly coal mine dust, include placing a sample of the particulate material in a container to define a pair of angularly oriented surfaces of the sample, directing an incident gamma-ray beam from a radiation source at one surface of the sample and detecting gamma-ray backscatter from the other surface of the sample with a radiation detector having an output operating a display to indicate incombustible content of the sample. The positioning of the source and detector along different surfaces of the sample permits the depth of the scattering volume defined by intersection of the incident beam and a detection cone from the detector to be selected such that variations in scattered radiation produced by variations in density of the sample are compensated by variations in the attenuation of the incident beam and the gamma-ray backscatter. 17 claims 5 figures

  18. A didactic proposal about Rutherford backscattering spectrometry with theoretic, experimental, simulation and application activities (United States)

    Corni, Federico; Michelini, Marisa


    Rutherford backscattering spectrometry is a nuclear analysis technique widely used for materials science investigation. Despite the strict technical requirements to perform the data acquisition, the interpretation of a spectrum is within the reach of general physics students. The main phenomena occurring during a collision between helium ions—with energy of a few MeV—and matter are: elastic nuclear collision, elastic scattering, and, in the case of non-surface collision, ion stopping. To interpret these phenomena, we use classical physics models: material point elastic collision, unscreened Coulomb scattering, and inelastic energy loss of ions with electrons, respectively. We present the educational proposal for Rutherford backscattering spectrometry, within the framework of the model of educational reconstruction, following a rationale that links basic physics concepts with quantities for spectra analysis. This contribution offers the opportunity to design didactic specific interventions suitable for undergraduate and secondary school students.

  19. Radiological Shielding Design for the Neutron High-Resolution Backscattering Spectrometer EMU at the OPAL Reactor (United States)

    Ersez, Tunay; Esposto, Fernando; Souza, Nicolas R. de


    The shielding for the neutron high-resolution backscattering spectrometer (EMU) located at the OPAL reactor (ANSTO) was designed using the Monte Carlo code MCNP 5-1.60. The proposed shielding design has produced compact shielding assemblies, such as the neutron pre-monochromator bunker with sliding cylindrical block shields to accommodate a range of neutron take-off angles, and in the experimental area - shielding of neutron focusing guides, choppers, flight tube, backscattering monochromator, and additional shielding elements inside the Scattering Tank. These shielding assemblies meet safety and engineering requirements and cost constraints. The neutron dose rates around the EMU instrument were reduced to < 0.5 µSv/h and the gamma dose rates to a safe working level of ≤ 3 µSv/h.

  20. Terahertz Imaging and Backscatter Radiography Probability of Detection Study for Space Shuttle Foam Inspections (United States)

    Ussery, Warren; Johnson, Kenneth; Walker, James; Rummel, Ward


    This slide presentation reviews the use of terahertz imaging and Backscatter Radiography in a probability of detection study of the foam on the external tank (ET) shedding and damaging the shuttle orbiter. Non-destructive Examination (NDE) is performed as one method of preventing critical foam debris during the launch. Conventional NDE methods for inspection of the foam are assessed and the deficiencies are reviewed. Two methods for NDE inspection are reviewed: Backscatter Radiography (BSX) and Terahertz (THZ) Imaging. The purpose of the Probability of Detection (POD) study was to assess performance and reliability of the use of BSX and or THZ as an appropriate NDE method. The study used a test article with inserted defects, and a sample of blanks included to test for false positives. The results of the POD study are reported.

  1. A unified approach for radiative losses and backscattering in optical waveguides

    International Nuclear Information System (INIS)

    Melati, D; Morichetti, F; Melloni, A


    Sidewall roughness in optical waveguides represents a severe impairment for the proper functionality of photonic integrated circuits. The interaction between the propagating mode and the roughness is responsible for both radiative losses and distributed backscattering. In this paper, a unified vision on these extrinsic loss phenomena is discussed, highlighting the fundamental role played by the sensitivity of the effective index n eff of the optical mode to waveguide width variations. The n w model presented applies to both 2D slab waveguides and 3D laterally confined waveguides and is in very good agreement with existing models that individually describe radiative loss or backscattering only. Experimental results are presented, demonstrating the validity of the n w model for arbitrary waveguide geometries and technologies. This approach enables an accurate description of realistic optical waveguides and provides simple design rules for optimization of the waveguide geometry in order to reduce the propagation losses generated by sidewall roughness. (paper)

  2. Experimental study of polarization and backscattering noise of resonator fiber optic gyro (United States)

    Ning, Liang; Guo, Lijun; Fang, Gang; Liu, Cihang


    We analyzed the parameters and main noise influence on resonator fiber optic gyro's finesse, and put forward the main way to improve the finesse. Then, we built the optical fiber ring resonator test system, inhibited the polarization fluctuation noise by using the polarization controller and polarization-laser, and at last took the backscattering noise tests. The experimental results showed that the inhibition of the polarization fluctuation noise has made the fiber optic resonant ring finesse increase from 64.67 to 84.57, resonant depth increase from 0.5033 to 0.7308. At the same time, we measured the intensity ratio of the Rayleigh backscattering light and main signal of 0.0267%. It provides a helpful reference for manufacturing of resonator fiber optic gyro.

  3. Measurement of reduced backscattering noise in laser-driven fiber optic gyroscopes. (United States)

    Lloyd, Seth W; Dangui, Vinayak; Digonnet, Michel J F; Fan, Shanhui; Kino, G S


    We report what we believe to be the first demonstration of a laser-driven fiber optic gyroscope (FOG) built with an air-core fiber. Its phase noise is measured to be 130 murad/ radicalHz. When the sensing fiber is replaced with a conventional fiber, this figure drops to 12 murad/ radicalHz. Comparison between these values suggests that the air-core fiber gyro is most likely not limited solely by backscattering noise but by reflections at the solid-core/air-core interface. By minimizing additional noise sources and reducing the air-core fiber loss to its theoretical limit (approximately 0.1 dB/km), we predict that the backscattering noise of the laser-driven air-core FOG will drop below the level of current FOGs. Compared with commercial FOGs, this FOG will exhibit a lower noise, improved thermal and mean-wavelength stability, and reduced magnetic-field sensitivity.

  4. Implementation of a near backscattering imaging system on the National Ignition Facility

    International Nuclear Information System (INIS)

    Mackinnon, A.J.; McCarville, T.; Piston, K.; Niemann, C.; Jones, G.; Reinbachs, I.; Costa, R.; Celeste, J.; Holtmeier, G.; Griffith, R.; Kirkwood, R.; MacGowan, B.; Glenzer, S.H.; Latta, M.R.


    A near backscattering imaging diagnostic system is being implemented on the first quad of beams on the National Ignition Facility. This diagnostic images diffusing scatter plates, placed around the final focus lenses on the National Ignition Facility target chamber, to quantitatively measure the fraction of light backscattered outside of the focusing cone angle of incident laser beam. A wide-angle imaging system relays an image of light scattered outside the lens onto a gated charge coupled device camera, providing 3 mm resolution over a 2 m field of view. To account for changes of the system throughput due to exposure to target debris the system will be routinely calibrated in situ at 532 and 355 nm using a dedicated pulsed laser source

  5. Microstructural evolution in adiabatic shear bands of copper at high strain rates: Electron backscatter diffraction characterization

    International Nuclear Information System (INIS)

    Tang Lin; Chen Zhiyong; Zhan Congkun; Yang Xuyue; Liu Chuming; Cai Hongnian


    The microstructural evolution of adiabatic shear bands in annealed copper with different large strains at high strain rates has been investigated by electron backscatter diffraction. The results show that mechanical twinning can occur with minimal contribution to shear localization under dynamic loading. Elongated ultrafine grains with widths of 100–300 nm are observed during the evolution of the adiabatic shear bands. A rotational dynamic recrystallization mechanism is proposed to explain the formation of the elongated ultrafine grains. - Highlights: ► The microstructural evolution of ASB is studied by electron backscatter diffraction. ► Twinning can occur in ASB while the contribution to shear localization is slight. ► Elongated ultrafine grains are observed during the evolution process of ASB. ► A possible mechanism is proposed to explain the microstructure evolution of ASB.

  6. Bulk elastic waves with unidirectional backscattering-immune topological states in a time-dependent superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Swinteck, N., E-mail:; Matsuo, S.; Runge, K.; Lucas, P.; Deymier, P. A. [Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721 (United States); Vasseur, J. O. [Institut d' Electronique, de Micro-électronique et de Nanotechnologie, UMR CNRS 8520, Cité Scientifique, 59652 Villeneuve d' Ascq Cedex (France)


    Recent progress in electronic and electromagnetic topological insulators has led to the demonstration of one way propagation of electron and photon edge states and the possibility of immunity to backscattering by edge defects. Unfortunately, such topologically protected propagation of waves in the bulk of a material has not been observed. We show, in the case of sound/elastic waves, that bulk waves with unidirectional backscattering-immune topological states can be observed in a time-dependent elastic superlattice. The superlattice is realized via spatial and temporal modulation of the stiffness of an elastic material. Bulk elastic waves in this superlattice are supported by a manifold in momentum space with the topology of a single twist Möbius strip. Our results demonstrate the possibility of attaining one way transport and immunity to scattering of bulk elastic waves.

  7. Design and development of the backscatter LIDAR ATLID for EarthCARE (United States)

    Le Hors, L.; Toulemont, Y.; Hélière, A.


    In the frame of the EarthCARE programme, Astrium France is currently developing one of the mission core instruments: the backscatter lidar ATLID. The EarthCARE mission is the third Earth Explorer Core Missions of the ESA Living Planet Programme, with a launch date planned in 2013. It addresses the interaction and impact of clouds and aerosols on the Earth's radiative budget. ATLID (ATmospheric LIDar), one of the four instruments of EarthCARE, shall determine vertical profiles of clouds and aerosols physical parameters (altitude, optical depth, backscatter ratio and depolarisation ratio) in synergy with other instruments. This paper presents the design and performance of the ATLID instrument, and relates the main development issues. The technical challenges and the main innovations are highlighted.

  8. Correlation Properties of the Backscattered Field in a Nonstationary Statistical Problem (United States)

    Gulin, O. É.; Yaroshchuk, I. O.


    The statistical problem of the scattering of wideband pulses by a random layered medium at normal incidence is considered in the framework of the wave approach in the space—time domain. Simulated correlation functions and power spectral densities of the backscattered field are presented. They extend the earlier findings concerning the backscattered field formation and also confirm and refine a number of conclusions drawn earlier from the behavior of the field’s statistical moments. The simulation technique is free from approximations commonly used in the statistical analysis of the propagation problems and can be used to study the statistical properties of the scattered field in a wide range of time intervals, as well as to find the limits of applicability of the approximate methods.

  9. Method and apparatus for shadow aperture backscatter radiography (SABR) system and protocol (United States)

    Shedlock, Daniel (Inventor); Jacobs, Alan M. (Inventor); Jacobs, Sharon Auerback (Inventor); Dugan, Edward (Inventor)


    A shadow aperture backscatter radiography (SABR) system includes at least one penetrating radiation source for providing a penetrating radiation field, and at least one partially transmissive radiation detector, wherein the partially transmissive radiation detector is interposed between an object region to be interrogated and the radiation source. The partially transmissive radiation detector transmits a portion of the illumination radiation field. A shadow aperture having a plurality of radiation attenuating regions having apertures therebetween is disposed between the radiation source and the detector. The apertures provide illumination regions for the illumination radiation field to reach the object region, wherein backscattered radiation from the object is detected and generates an image by the detector in regions of the detector that are shadowed by the radiation attenuation regions.

  10. Quantitative Test of the Evolution of Geant4 Electron Backscattering Simulation

    CERN Document Server

    Basaglia, Tullio; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Sung Hun; Pia, Maria Grazia; Saracco, Paolo


    Evolutions of Geant4 code have affected the simulation of electron backscattering with respect to previously published results. Their effects are quantified by analyzing the compatibility of the simulated electron backscattering fraction with a large collection of experimental data for a wide set of physics configuration options available in Geant4. Special emphasis is placed on two electron scattering implementations first released in Geant4 version 10.2: the Goudsmit-Saunderson multiple scattering model and a single Coulomb scattering model based on Mott cross section calculation. The new Goudsmit-Saunderson multiple scattering model appears to perform equally or less accurately than the model implemented in previous Geant4 versions, depending on the electron energy. The new Coulomb scattering model was flawed from a physics point of view, but computationally fast in Geant4 version 10.2; the physics correction released in Geant4 version 10.2p01 severely degrades its computational performance. Evolutions in ...

  11. Assessment Of Backscatter Variations In Tundra Regions With Respect To Uncertainties In Soil Moisture Retrieval (United States)

    Hogstrom, Elin; Bartsch, Annett; Gouttevin, Isabelle


    Knowledge of surface hydrology is relevant for many applications, including improving our understanding of permafrost response and feedback in a changing climate. Advances in remote-sensing techniques and retrieval algorithms can provide a range of land surface parameters, such as radar backscatter derived surface soil moisture. It has previously been pointed out that soil moisture retrieval can be challenging in high latitudes. This study investigates backscatter variability other than associated with changing soil moisture with focus on issues specific to the arctic, notably on variations related to water bodies. ENVISAT ASAR data are utilized for quantification of potential impacts on Metop ASCAT soil moisture retrieval during the snow free period. Ice cover on lakes is identified as a mayor contributor of impact.

  12. Practical implications of backscatter from outside the patient on the dose distribution during total body irradiation

    International Nuclear Information System (INIS)

    Van Dam, J.; Rijnders, A.; Vanuytsel, L.; Zhang, H.-Z.


    Total body irradiation (TBI) sometimes requires the set-up of the patient very close to the wall of the treatment room in order to obtain sufficiently large irradiation fields. Under these conditions, backscattered electrons can become clinically important. In the present study, an attempt was made to quantify the dose contribution to the patient from these electrons. Measurements were performed both in experimental conditions and on patients during their TBI treatment. It is concluded that, with the patient close to the wall, backscattered electrons constitute a significant (up to 20% of the dose obtained under electronic equilibrium at the exit port of the beam) radiation dose which can (under certain conditions) influence measurements of exit dose leading to an overestimation of the midline dose and contribute a suuperficial irradiation of the patient without therapeutic benefit. This problem can be solved by interposing a 2 cm thick low-Z absorber between wall and patient. 9 refs.; 5 figs.; 1 table

  13. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas. (United States)

    Gualda, Emilio J; Vázquez de Aldana, Javier R; Martínez-García, M Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M


    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures.

  14. Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets (United States)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun


    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  15. Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets (United States)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun


    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  16. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.


    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  17. Image combination enhancement method for X-ray compton back-scattering security inspection body scanner

    International Nuclear Information System (INIS)

    Wang Huaiying; Zhang Yujin; Yang Lirui; Li Dong


    As for X-ray Compton Back-Scattering (CBS) body scanner, image clearness is very important for the performance of detecting the contraband hidden on the body. A new image combination enhancement method is provided based on characteristics of CBS body images and points of human vision. After processed by this method, the CBS image will be obviously improved with clear levels, distinct outline and uniform background. (authors)

  18. Energy analyzer for Auger electron spectroscopy and low-energy backscattering ion spectroscopy

    International Nuclear Information System (INIS)

    Volkov, S.S.; Gorelik, V.A.; Gutenko, V.T.; Protopopov, O.D.; Trubitsin, A.A.; Shuvalova, Z.A.; Yakushev, G.A.


    Energy analyzer for electron Auger spectroscopy and low-energy backscattering ion spectroscopy is described. Analyzer presents one-cascade variant of cylindrical mirror with second-order focusing. Energy relative resolution is continuously adjusted within 0.2-1.2% limits. Signal/noise relation by Cu Auger-line at 1 muA current of exciting beam changes upper limit of range 150-450

  19. Taking apart the enhanced backscattering cone: Interference fringes from reciprocal paths in multiple light scattering

    International Nuclear Information System (INIS)

    Bret, Boris P. J.; Ferreira, Flavio P.; Nunes-Pereira, Eduardo J.; Belsley, Michael


    We report the decomposition of the enhanced backscattering cone into its constitutive interference fringes. These fringes are due to the constructive interference between reciprocal paths of any multiply scattered wave after ensemble averaging. An optical setup combining a two-point continuous-wave illumination and matching detection allows the observation of the fringes and, therefore, the quantitative characterization of the Green's function for light propagation between the two points in a multiple-scattering media.

  20. Investigation by the Rutherford backscattering method of impurity deposited on the T-3M tokamak diaphragm

    International Nuclear Information System (INIS)

    Danelyan, L.S.; Egorova, I.M.; Kulikauskas, V.S.; Baratov, D.G.; Belykh, T.A.


    The Rutherford backscattering of helium-4 ions was used for investigation of impurity deposited on the annular graphite diaphragm as a result of the interaction between hydrogen plasma and liquid-metal spray limiter. The experimental RBS spectra distributions of the impurity elements surface densities along the direction from plasma to the chamber wall are presented as depth of the elements. The erosion coefficient of the main liquid-metal limiter element has been estimated

  1. Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet

    Directory of Open Access Journals (Sweden)

    S. E. Milan


    Full Text Available A common feature of evening near-range ionospheric backscatter in the CUTLASS Iceland radar field of view is two parallel, approximately L-shell-aligned regions of westward flow which are attributed to irregularities in the auroral eastward electrojet region of the ionosphere. These backscatter channels are separated by approximately 100–200 km in range. The orientation of the CUTLASS Iceland radar beams and the zonally aligned nature of the flow allows an approximate determination of flow angle to be made without the necessity of bistatic measurements. The two flow channels have different azimuthal variations in flow velocity and spectral width. The nearer of the two regions has two distinct spectral signatures. The eastern beams detect spectra with velocities which saturate at or near the ion-acoustic speed, and have low spectral widths (less than 100 m s–1, while the western beams detect lower velocities and higher spectral widths (above 200 m s–1. The more distant of the two channels has only one spectral signature with velocities above the ion-acoustic speed and high spectral widths. The spectral characteristics of the backscatter are consistent with E-region scatter in the nearer channel and upper-E-region or F-region scatter in the further channel. Temporal variations in the characteristics of both channels support current theories of E-region turbulent heating and previous observations of velocity-dependent backscatter cross-section. In future, observations of this nature will provide a powerful tool for the investigation of simultaneous E- and F-region irregularity generation under similar (nearly co-located or magnetically conjugate electric field conditions.Key words. Auroral ionosphere · Ionospheric irregularities · Plasma convection

  2. Assessing Seasonal Backscatter Variations with Respect to Uncertainties in Soil Moisture Retrieval in Siberian Tundra Regions

    Directory of Open Access Journals (Sweden)

    Elin Högström


    Full Text Available Knowledge of surface hydrology is essential for many applications, including studies that aim to understand permafrost response to changing climate and the associated feedback mechanisms. Advanced remote sensing techniques make it possible to retrieve a range of land-surface variables, including radar retrieved soil moisture (SSM. It has been pointed out before that soil moisture retrieval from satellite data can be challenging at high latitudes, which correspond to remote areas where ground data are scarce and the applicability of satellite data of this type is essential. This study investigates backscatter variability other than associated with changing soil moisture in order to examine the possible impact on soil moisture retrieval. It focuses on issues specific to SSM retrieval in the Arctic, notably variations related to tundra lakes. ENVISAT Advanced Synthetic Aperture Radar (ASAR Wide Swath (WS, 120 m data are used to understand and quantify impacts on Metop (AAdvanced Scatterometer (ASCAT, 25 km soil moisture retrieval during the snow free period. Sites of interest are chosen according to ASAR WS availability, high or low agreement between output from the land surface model ORCHIDEE and ASCAT derived SSM. Backscatter variations are analyzed with respect to the ASCAT footprint area. It can be shown that the low model agreement is related to water fraction in most cases. No difference could be detected between periods with floating ice (in snow off situation and ice free periods at the chosen sites. The mean footprint backscatter is however impacted by partial short term surface roughness change. The water fraction correlates with backscatter deviations (relative to a smooth water surface reference image within the ASCAT footprint areas (R = 0.91

  3. 3D invariant embedding model for backscattering electrons applied to materials characterization

    International Nuclear Information System (INIS)

    Figueroa, C.; Nieva, N.; Heluani, S.P.


    In this work, the results of a 3D model used to describe the fraction of backscattered electrons, together with its energy and angular distributions, are reported. This 3D model is the result of improvements in the Invariant Embedding Approach to Microanalysis (IEAM). Comparisons with experiment show that the theoretical results follow the general trend of experimental data, when parameters (such as atomic number, energy of the impinging electrons and tilted angle) are changed

  4. Backscattered electron technique used for studying the grain boundary structure in polycrystals

    International Nuclear Information System (INIS)

    Lopes, Luiz Carlos Rolim; Thomson, Chris Boyd; Randle, Valerie


    In this work the electron backscatter diffraction technique has been used to study the grain boundary character distribution in a austenitic steel and a ordered intermetallic Fe Al. For the first material it has been found that the hot rolling and solubilization process produce grain boundary character distribution with 1/4 of Σ = 3 interface. For the intermetallic Fe Al it was found that Σ = 1 and Σ = 5 interfaces to do not show tendency to show intergranular cracking. (author)

  5. Ultrasonic tissue characterization with integrated backscatter. Acute myocardial ischemia, reperfusion, and stunned myocardium in patients

    Energy Technology Data Exchange (ETDEWEB)

    Milunski, M.R.; Mohr, G.A.; Perez, J.E.; Vered, Z.; Wear, K.A.; Gessler, C.J.; Sobel, B.E.; Miller, J.G.; Wickline, S.A. (Washington Univ., St. Louis, MO (USA))


    We have previously shown in studies of experimental animals that myocardium exhibits a cardiac cycle-dependent variation of integrated backscatter that reflects regional myocardial contractile performance and that is blunted promptly after arterial occlusion and recovers after reperfusion. To define the clinical utility of ultrasonic tissue characterization with integrated backscatter for detection of acute myocardial infarction and reperfusion, 21 patients (14 men and seven women) were studied in the cardiac care unit within the first 24 hours (mean time, 11.3 hours; range, 3.5-23.8 hours) after the onset of symptoms indicative of acute myocardial infarction with conventional two-dimensional and M-mode echocardiography and with analysis of integrated backscatter. The magnitude of cyclic variation of integrated backscatter was measured from several sites within acute infarct regions and normal regions remote from the infarct zone for each patient. The average magnitude of cyclic variation among all patients (n = 21) was 4.8 +/- 0.5 dB in normal regions compared with 0.8 +/- 0.3 dB in infarct regions (p less than 0.05) within the first 24 hours after the onset of symptoms. Among the patients who had two studies, 15 (mean, 7.1 days; range, 2-31 days for second study) underwent coronary arteriography to define vessel patency. In patients with vessels with documented patency (n = 10), the magnitude of cyclic variation in infarct regions increased over time from 1.3 +/- 0.6 to 2.5 +/- 0.5 dB from the initial to final study (p less than 0.05). Patients with occluded infarct-related arteries (n = 5) exhibited no significant recovery of cyclic variation (0.3 +/- 0.3-0.6 +/- 0.3 dB). A blinded analysis of standard two-dimensional echocardiographic images revealed no significant recovery of wall thickening in either group over the same time intervals.

  6. Suspended sediment assessment by combining sound attenuation and backscatter measurements - analytical method and experimental validation (United States)

    Guerrero, Massimo; Di Federico, Vittorio


    The use of acoustic techniques has become common for estimating suspended sediment in water environments. An emitted beam propagates into water producing backscatter and attenuation, which depend on scattering particles concentration and size distribution. Unfortunately, the actual particles size distribution (PSD) may largely affect the accuracy of concentration quantification through the unknown coefficients of backscattering strength, ks2, and normalized attenuation, ζs. This issue was partially solved by applying the multi-frequency approach. Despite this possibility, a relevant scientific and practical question remains regarding the possibility of using acoustic methods to investigate poorly sorted sediment in the spectrum ranging from clay to fine sand. The aim of this study is to investigate the possibility of combining the measurement of sound attenuation and backscatter to determine ζs for the suspended particles and the corresponding concentration. The proposed method is moderately dependent from actual PSD, thus relaxing the need of frequent calibrations to account for changes in ks2 and ζs coefficients. Laboratory tests were conducted under controlled conditions to validate this measurement technique. With respect to existing approaches, the developed method more accurately estimates the concentration of suspended particles ranging from clay to fine sand and, at the same time, gives an indication on their actual PSD.

  7. The research of thickness measurement base on γ-ray compton backscattering

    International Nuclear Information System (INIS)

    Chen Xinnan; Wang Guobao; Chen Yannan


    The source and detector should be on the same side in many industrial cases, such as measurement of large scale pipes or steel plates and some large objects through which gamma ray can not transmit. Unlike the transmission method, the advantage of Compton backscattering is the flexible method of layout between source and detector. The research of Compton backscattering is very important to solve these special problems. This work describes a new method of layout between the source and the detector. Using the Monte Carol method several key factors which were associated with the measurement were also simulated, such as collimator dimension, the distance between the detector and the sample, source intensity, measured pieces. The result indicated this measurement method could entirely meet the requirement. The simulated result from Monte Carol was proved by the experiment. The experiments accord with the simulated result: the bigger the collimator diameter is, the bigger the counting rate received by detector is, the less the linear range is; For the organic glass, 5-8 mm is the best distance range between detector and samples. Different thickness associate with different distance and collimator dimension. These results provide a good technical base for research of thickness measurement based on Compton backscattering, offer a guide to practical application. (authors)

  8. Analysis of dose and risk associated with the use of backscatter vans

    International Nuclear Information System (INIS)

    Correa, Samanda C.A.; Aquino, Josilto O.; Silva, Ademir X.


    In recent years, imaging technology using radiation has been gaining in importance for the screening of persons for security reasons and in order to detect contraband. And currently, new X-ray detection technologies have been introduced such as the Backscatter Van. The Backscatter Van is used in port and border security, force protection, urban surveillance, and other critical security applications in order to seize drugs, explosives, and more. The system is mobile, affordable and the faster, more effective, and less expensive than any mobile screening solution in the marketplace. However, although the application of this equipment in the national security area is indeed relevant, its use has caused a great deal of controversy, especially with regard to the doses absorbed and to the cancer induction risk associated with these exposures. The aim of this study is to use the Monte Carlo MCNPX code and the male adult voxel (MAX) and female adult voxel (FAX) phantoms, to evaluate the absorbed dose, effective dose and cancer induction risk values associated with the exposures of individuals submitted to Backscatter Van. The effective dose values were calculated as recommended by the new ICRP 103 and the cancer induction risk values were estimated through the BEIR VII document. (author)

  9. Analysis of dose and risk associated with the use of backscatter vans

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Samanda C.A.; Aquino, Josilto O., E-mail:, E-mail: [Comissao Nacional de Energia Nuclear (DIAPI/CGMI/CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao Geral de Instalacoes Medicas e Industriais. Div. de Aplicacoes Industriais; Souza, Edmilson M., E-mail: emonteiro@nuclear.ufrj.b [Centro Universitario Estadual da Zona Oeste (CAPI/UEZO), Rio de Janeiro, RJ (Brazil); Silva, Ademir X., E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear


    In recent years, imaging technology using radiation has been gaining in importance for the screening of persons for security reasons and in order to detect contraband. And currently, new X-ray detection technologies have been introduced such as the Backscatter Van. The Backscatter Van is used in port and border security, force protection, urban surveillance, and other critical security applications in order to seize drugs, explosives, and more. The system is mobile, affordable and the faster, more effective, and less expensive than any mobile screening solution in the marketplace. However, although the application of this equipment in the national security area is indeed relevant, its use has caused a great deal of controversy, especially with regard to the doses absorbed and to the cancer induction risk associated with these exposures. The aim of this study is to use the Monte Carlo MCNPX code and the male adult voxel (MAX) and female adult voxel (FAX) phantoms, to evaluate the absorbed dose, effective dose and cancer induction risk values associated with the exposures of individuals submitted to Backscatter Van. The effective dose values were calculated as recommended by the new ICRP 103 and the cancer induction risk values were estimated through the BEIR VII document. (author)

  10. Clean image synthesis and target numerical marching for optical imaging with backscattering light. (United States)

    Xu, Min; Pu, Yang; Wang, Wubao


    Scanning backscattering imaging and independent component analysis (ICA) are used to probe targets hidden in the subsurface of a turbid medium. A new correction procedure is proposed and used to synthesize a "clean" image of a homogeneous host medium numerically from a set of raster-scanned "dirty" backscattering images of the medium with embedded targets. The independent intensity distributions on the surface of the medium corresponding to individual targets are then unmixed using ICA of the difference between the set of dirty images and the clean image. The target positions are localized by a novel analytical method, which marches the target to the surface of the turbid medium until a match with the retrieved independent component is accomplished. The unknown surface property of the turbid medium is automatically accounted for by this method. Employing clean image synthesis and target numerical marching, three-dimensional (3D) localization of objects embedded inside a turbid medium using independent component analysis in a backscattering geometry is demonstrated for the first time, using as an example, imaging a small piece of cancerous prostate tissue embedded in a host consisting of normal prostate tissue.

  11. Backscattering spectrometry device for identifying unknown elements present in a workpiece (United States)

    Doyle, Barney L.; Knapp, James A.


    A backscattering spectrometry method and device for identifying and quantifying impurities in a workpiece during processing and manufacturing of that workpiece. While the workpiece is implanted with an ion beam, that same ion beam backscatters resulting from collisions with known atoms and with impurities within the workpiece. Those ions backscatter along a predetermined scattering angle and are filtered using a self-supporting filter to stop the ions with a lower energy because they collided with the known atoms of the workpiece of a smaller mass. Those ions which pass through the filter have a greater energy resulting from impact with impurities having a greater mass than the known atoms of the workpiece. A detector counts the number and measures the energy of the ions which pass through the filter. From the energy determination and knowledge of the scattering angle, a mass calculation determines the identity, and from the number and solid angle of the scattering angle, a relative concentration of the impurity is obtained.

  12. Height dependence of the observed spectrum of radar backscatter from HF-induced ionospheric Langmuir turbulence (United States)

    Fejer, J. A.; Sulzer, M. P.; Djuth, F. T.


    Results are presented of observations of the spectrum of the 430-MHz radar backscatter from HF-induced Langmuir turbulence with height discrimination. During very stable ionospheric conditions under which the height of the below-threshold backscatter spectrum changed by less than 300 m during a 7-min period, a 20-s-long temporary increase in the HF power from 3 MW ERP to 38-MW-equivalent-radiated HF power is found to result in subsequent strong above-threshold spectra extending to heights up to 1200 m greater than the height of the below-threshold spectrum for more than a minute. The generation of irregularities in the plasma density during the 20 s of enhanced HF power is suggested as a possible cause of this persistence of strong above-threshold spectra at greater heights. The initial temporal evolution of the backscatter spectrum from Langmuir turbulence after the start of HF transmissions is observed for different heights. The observational results are compared with the predictions of existing theories of Langmuir turbulence.

  13. Experimental evaluation of multiple Compton backscattering of gamma rays in copper

    International Nuclear Information System (INIS)

    Sabharwal, Arvind D.; Singh, Manpreet; Singh, Bhajan; Sandhu, B.S.


    The gamma ray photons continue to soften in energy as the number of scatterings increases in thick target, and results in the generation of singly and multiply scattered events. The number of these multiply scattered events increases with an increase in target thickness and saturates beyond a particular target thickness known as saturation depth. The present experiment is undertaken to study the saturation depth for 279 and 320 keV incident gamma ray photons multiply backscattered from copper targets of varying thickness. The backscattered photons are detected by a Nal(Tl) gamma detector whose pulse-height distribution is converted into a photon spectrum with the help of an inverse matrix approach. To extract the contribution of multiply backscattered photons only, the spectrum of singly scattered photon is reconstructed analytically. We observe that the numbers of multiply scattered events increases with an increase in target thickness and then saturate. The saturation depth is found to be decreasing with increase in incident gamma energy. (author)

  14. Seafloor Backscatter Image of North of Santa Rosa Island, Channel Islands National Marine Sanctuary (8m resolution tif) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents an 8 meter resolution backscatter of the seafloor south of Santa Rosa Island in Channel Islands National Marine Sanctuary. It was acquired...

  15. NOAA TIFF Image - 50m Backscatter, Charleston Bump - Deep Coral Priority Areas - Nancy Foster - (2006), UTM 17N NAD83 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 30x30 meter cell size representing the backscatter intensity of the Charleston Bump off of the South Atlantic Bight,...

  16. Proceedings of the international advisory committee on 'biomolecular dynamics instrument DNA' and the workshop on 'biomolecular dynamics backscattering spectrometers'

    International Nuclear Information System (INIS)

    Arai, Masatoshi; Aizawa, Kazuya; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki


    A workshop entitled 'Biomolecular Dynamics Backscattering Spectrometers' was held on February 27th - 29th, 2008 at J-PARC Center, Japan Atomic Energy Agency. This workshop was planned to be held for aiming to realize an innovative neutron backscattering instrument, namely DNA, in the MLF and thus four leading scientists in the field of neutron backscattering instruments were invited as the International Advisory Committee (IAC member: Dr. Dan Neumann (Chair); Prof. Ferenc Mezei; Dr. Hannu Mutka; Dr. Philip Tregenna-Piggott) for DNA from institutes in the United States, France and Switzerland, where backscattering instruments are in-service. It was therefore held in the form of lecture anterior and then in the form of the committee posterior. This report includes the executive summary of the IAC and materials of the presentations in the IAC and the workshop. (author)

  17. Backscatter Mosaic used to identify, delineate and classify moderate-depth benthic habitats around St. John, USVI (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 2x2 meter resolution backscatter mosaic of the moderate-depth portion of the NPS's Virgin Islands Coral Reef National Monument, south of St....

  18. Landmine Detection: on the Role of Soil Composition in the Imaging Capabilities of Gamma-ray Compton Backscattering

    International Nuclear Information System (INIS)

    Cortes, M.L.; Merchan, E.; Blanco, W.J.; Cristancho, F.; Gerl, J.; Ameil, F.


    Two issues related with the use of γ-ray Compton backscattering as an imaging technique are addressed: γ-soil interaction, and image processing. Promising methodologies are described in both topics. (author)

  19. CRED Reson 8101 multibeam backscatter data of Baker Island, Pacific Remote Island Areas, Central Pacific in netCDF format (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Baker Island, Pacific Island Areas, Central Pacific. These...

  20. CRED Reson 8101 multibeam backscatter data of Howland Island, Pacific Remote Island Areas, Central Pacific in netCDF format (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Howland Island, Pacific Island Areas, Central Pacific. These...

  1. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geotiff represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography...

  2. NOAA TIFF Graphic - 0.5 meter Backscatter Mosaic of St. John, U.S. Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the southern shore of St. John, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  3. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 1 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team...

  4. NOAA ESRI Geotiff - 3m Backscatter Mosaic, Puerto Rico (Isla de Vieques) - UTM 20N NAD83 (NCEI Accession 0131852) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 3 meter resolution backscatter mosaic of selected portions of seafloor around Isla de Vieques, Puerto Rico. NOAA's NOS/NCCOS/CCFHR, in...

  5. Characterization of the bio-optical anomaly and diurnal variability of particulate matter, as seen from scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    H. Loisel


    Full Text Available The variability of inherent optical properties is investigated in the ultra-oligotrophic waters of the Mediterranean Sea sampled during the BOUM experiment performed during early summer 2008. Bio-optical relationships found for ultra-oligotrophic waters of the three anticyclonic gyres sampled significantly depart from the mean standard relationships provided for the global ocean, confirming the peculiar character of these Mediterranean waters. These optical anomalies are diversely related to the specific biological and environmental conditions occurring in the studied ecosystem. Specifically, the surface specific phytoplankton absorption coefficient exhibits values lower than those expected from the general relationships mainly in relation with a high contribution of relatively large sized phytoplankton. Conversely, the particulate backscattering coefficient, bbp, values are much higher than the mean standard values for a given chlorophyll-a concentration, TChl-a. This feature can presumably be related to the relevant influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column. The present measurements also show that the Mediterranean Sea is greener than TChl-a alone indicates, as already stressed in previous studies. This color anomaly is partly explained by the estimated colored dissolved organic matter and submicrometer particles absorption coefficients, and to a greater extent by the high bbp/TChl-a values assuming that these particles backscatter light similarly in the green and blue parts of the visible spectrum. The diel variation of both the particulate matter attenuation and backscattering coefficients were also investigated specifically. Despite some differences in the timing and the magnitude of the daily oscillations found for these optical parameters, potential for the backscattering coefficient daily oscillation to

  6. Phytases for improved iron absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.


    Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains...

  7. Atomic absorption instrument functional description

    International Nuclear Information System (INIS)

    Bystroff, R.I.; Boyle, W.G. Jr.; Barton, G.W. Jr.


    This report describes a proposed system for automating atomic absorption analysis. The system consists of two atomic absorption instruments and an automatic sampler that can be attached to either instrument. A computer program controls the sampling and gathers data. The program then uses the data to perform bookkeeping, data processing, and report writing

  8. Multifunctional hybrids for electromagnetic absorption

    Energy Technology Data Exchange (ETDEWEB)

    Huynen, I. [Research Center in Micro and Nanoscopic Materials and Electronic Devices, CeRMiN, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Quievy, N. [Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Bailly, C. [Research Center in Micro and Nanoscopic Materials and Electronic Devices, CeRMiN, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Mechanics, Materials and Civil Engineering (iMMC), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Bollen, P. [Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Mechanics, Materials and Civil Engineering (iMMC), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Detrembleur, C. [Center for Education and Research on Macromolecules (CERM), University of Liege, Sart-Tilman B6a, 4000 Liege (Belgium); Eggermont, S.; Molenberg, I. [Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Thomassin, J.M.; Urbanczyk, L. [Center for Education and Research on Macromolecules (CERM), University of Liege, Sart-Tilman B6a, 4000 Liege (Belgium)


    Highlights: > EM absorption requires low dielectric constant and {approx}1 S/m electrical conductivity. > New hybrids were processed with CNT-filled polymer foam inserted in Al honeycomb. > The EM absorption in the GHz range is superior to any known material. > A closed form model is used to guide the design of the hybrid. > The architectured material is light with potential for thermal management. - Abstract: Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management.

  9. Optical absorption of irradiated carbohydrates

    International Nuclear Information System (INIS)

    Supe, A.A.; Tiliks, Yu.E.


    The optical absorption spectra of γ-irradiated carbohydrates (glucose, lactose, sucrose, maltose, and starch) and their aqueous solutions were studied. The comparison of the data obtained with the determination of the concentrations of molecular and radical products of radiolysis allows the absorption bands with maxima at 250 and 310 nm to be assigned to the radicals trapped in the irradiated carbohydrates

  10. Water absorption in brick masonry

    NARCIS (Netherlands)

    Brocken, H.J.P.; Smolders, H.R.


    The water absorption in brick, mortar that was cured separately, and masonry samples was studied using NMR. Models of the moisture transport are usually formulated on the basis of a diffusion equation. In the case of water absorption in separate brick and mortar samples, the moisture diffusivity in

  11. Multifunctional hybrids for electromagnetic absorption

    International Nuclear Information System (INIS)

    Huynen, I.; Quievy, N.; Bailly, C.; Bollen, P.; Detrembleur, C.; Eggermont, S.; Molenberg, I.; Thomassin, J.M.; Urbanczyk, L.


    Highlights: → EM absorption requires low dielectric constant and ∼1 S/m electrical conductivity. → New hybrids were processed with CNT-filled polymer foam inserted in Al honeycomb. → The EM absorption in the GHz range is superior to any known material. → A closed form model is used to guide the design of the hybrid. → The architectured material is light with potential for thermal management. - Abstract: Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management.

  12. Atmospheric absorption of sound - Update (United States)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.


    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  13. Intestinal Absorption of Thyroid Hormone

    NARCIS (Netherlands)

    N. Kelderman-Bolk (Nienke)


    textabstractIn this thesis the treatment of hypothyroidism and absorption of T4 is described from a clinical and basic point of view. Put together the thesis gives insight in the factors influencing LT4 absorption and its results have influenced the timing of LT4 intake.

  14. Tropical Forest Backscatter Anomaly Evident in SeaWinds Scatterometer Morning Overpass Data During 2005 Drought in Amazonia (United States)

    Frolking, S. E.; Milliman, T.; Palace, M. W.; Wisser, D.; Lammers, R. B.; Fahnestock, M. A.


    A severe drought occurred in many portions of Amazonia in the dry season (June-September) of 2005. We analyzed ten years (7/99-10/09) of SeaWinds active microwave Ku-band backscatter data collected over the Amazon Basin, developing a monthly climatology and monthly anomalies from that climatology in an effort to detect landscape responses to this drought. We compared these to seasonal accumulating water deficit anomalies generated using Tropical Rainfall Monitoring Mission (TRMM) precipitation data (1999-2009) and 100 mm/mo evapotranspirative demand as a water deficit threshold. There was significant interannual variability in monthly mean backscatter only for ascending (early morning) overpass data, and little interannual variability in monthly mean backscatter for descending (late afternoon) overpass data. Strong negative anomalies in both ascending-overpass backscatter and accumulating water deficit developed during July-October 2005, centered on the southwestern Amazon Basin (Acre and western Amazonas states in Brazil; Madre de Dios state in Peru; Pando state in Bolivia). During the 2005 drought, there was a strong spatial correlation between morning overpass backscatter anomalies and water deficit anomalies. We hypothesize that as the drought persisted over several months, the forest canopy was increasingly unable to recover full leaf moisture content over night, and the early morning overpass backscatter data became anomalously low. This is the first reporting of tropical wet forest seasonal drought detection by active microwave scatterometry.

  15. The effect of artificial rain on backscattered acoustic signal: first measurements (United States)

    Titchenko, Yuriy; Karaev, Vladimir; Meshkov, Evgeny; Goldblat, Vladimir

    The problem of rain influencing on a characteristics of backscattered ultrasonic and microwave signal by water surface is considered. The rain influence on backscattering process of electromagnetic waves was investigated in laboratory and field experiments, for example [1-3]. Raindrops have a significant impact on backscattering of microwave and influence on wave spectrum measurement accuracy by string wave gauge. This occurs due to presence of raindrops in atmosphere and modification of the water surface. For measurements of water surface characteristics during precipitation we propose to use an acoustic system. This allows us obtaining of the water surface parameters independently on precipitation in atmosphere. The measurements of significant wave height of water surface using underwater acoustical systems are well known [4, 5]. Moreover, the variance of orbital velocity can be measure using these systems. However, these methods cannot be used for measurements of slope variance and the other second statistical moments of water surface that required for analyzing the radar backscatter signal. An original design Doppler underwater acoustic wave gauge allows directly measuring the surface roughness characteristics that affect on electromagnetic waves backscattering of the same wavelength [6]. Acoustic wave gauge is Doppler ultrasonic sonar which is fixed near the bottom on the floating disk. Measurements are carried out at vertically orientation of sonar antennas towards water surface. The first experiments were conducted with the first model of an acoustic wave gauge. The acoustic wave gauge (8 mm wavelength) is equipped with a transceiving antenna with a wide symmetrical antenna pattern. The gauge allows us to measure Doppler spectrum and cross section of backscattered signal. Variance of orbital velocity vertical component can be retrieved from Doppler spectrum with high accuracy. The result of laboratory and field experiments during artificial rain is presented

  16. Optical absorption of silicon nanowires

    International Nuclear Information System (INIS)

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stiévenard, D.; Lévêque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.


    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  17. Subgap Absorption in Conjugated Polymers (United States)

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.


    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  18. Sabine absorption coefficients to random incidence absorption coefficients

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho


    into random incidence absorption coefficients for porous absorbers are investigated. Two optimization-based conversion methods are suggested: the surface impedance estimation for locally reacting absorbers and the flow resistivity estimation for extendedly reacting absorbers. The suggested conversion methods...

  19. Absorption factor for cylindrical samples

    International Nuclear Information System (INIS)

    Sears, V.F.


    The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)

  20. Quantifying quagga mussel veliger abundance and distribution in Copper Basin Reservoir (California) using acoustic backscatter. (United States)

    Anderson, Michael A; Taylor, William D


    Quagga mussels (Dreissena bugensis) have been linked to oligotrophication of lakes, alteration of aquatic food webs, and fouling of infrastructure associated with water supply and power generation, causing potentially billions of dollars in direct and indirect damages. Understanding their abundance and distribution is key in slowing their advance, assessing their potential impacts, and evaluating effectiveness of control strategies. Volume backscatter strength (Sv) measurements at 201- and 430-kHz were compared with quagga mussel veliger and zooplankton abundances determined from samples collected using a Wisconsin closing net from the Copper Basin Reservoir on the Colorado River Aqueduct. The plankton within the lower portion of the water column (>18 m depth) was strongly dominated by D-shaped quagga mussel veligers, comprising up to 95-99% of the community, and allowed direct empirical measurement of their mean backscattering cross-section. The upper 0-18 m of the water column contained a smaller relative proportion of veligers based upon net sampling. The difference in mean volume backscatter strength at these two frequencies was found to decrease with decreasing zooplankton abundance (r(2) = 0.94), allowing for correction of Sv due to the contribution of zooplankton and the determination of veliger abundance in the reservoir. Hydroacoustic measurements revealed veligers were often present at high abundances (up to 100-200 ind L(-1)) in a thin 1-2 m layer at the thermocline, with considerable patchiness in their distribution observed along a 700 m transect on the reservoir. Under suitable conditions, hydroacoustic measurements can rapidly provide detailed information on the abundance and distribution of quagga mussel veligers over large areas with high horizontal and vertical resolution. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Investigating the correlation between radar backscatter and in situ soil property measurements (United States)

    Han, Deok; Vahedifard, Farshid; Aanstoos, James V.


    Utilizing remote sensing techniques to extract soil properties can facilitate several engineering applications for large-scale monitoring and modeling purposes such as earthen levees monitoring, landslide mapping, and off-road mobility modeling. This study presents results of statistical analyses to investigate potential correlations between multiple polarization radar backscatter and various physical soil properties. The study was conducted on an approximately 3 km long section of earthen levees along the lower Mississippi river as part of the development of remote levee monitoring methods. Polarimetric synthetic aperture radar imagery from UAVSAR was used along with an extensive set of in situ soil properties. The following properties were analyzed from the top 30-50 cm of soil: texture (sand and clay fraction), penetration resistance (sleeve friction and cone tip resistance), saturated hydraulic conductivity, field capacity, permanent wilting point, and porosity. The results showed some correlation between the cross-polarized (HV) radar backscatter coefficients and most of these properties. A few soil properties, like clay fraction, showed similar but weaker correlations with the co-polarized channels (HH and VV). The correlations between the soil properties and radar backscatter were analyzed separately for the river side and land side of the levee. It was found that the magnitude and direction of the correlation for most of the soil properties noticeably differed between the river and the land sides. The findings of this study can be a good starting point for scattering modelers in a pursuit of better models for radar scattering at cross polarizations which would include more diverse set of soil parameters.

  2. On the collocation between dayside auroral activity and coherent HF radar backscatter

    Directory of Open Access Journals (Sweden)

    J. Moen

    Full Text Available The 2D morphology of coherent HF radar and optical cusp aurora has been studied for conditions of predominantly southward IMF conditions, which favours low-latitude boundary layer reconnection. Despite the variability in shape of radar cusp Doppler spectra, the spectral width criterion of > 220 m s–1 proves to be a robust cusp discriminator. For extended periods of well-developed radar backscatter echoes, the equatorward boundary of the > 220 m s–1 spectral width enhancement lines up remarkably well with the equatorward boundary of the optical cusp aurora. The spectral width boundary is however poorly determined during development and fading of radar cusp backscatter. Closer inspection of radar Doppler profile characteristics suggests that a combination of spectral width and shape may advance boundary layer identification by HF radar. For the two December days studied the onset of radar cusp backscatter occurred within pre-existing 630.0 nm cusp auroral activity and appear to be initiated by sunrise, i.e. favourable radio wave propagation conditions had to develop. Better methods are put forward for analysing optical data, and for physical interpretation of HF radar data, and for combining these data, as applied to detection, tracking, and better understanding of dayside aurora. The broader motivation of this work is to develop wider use by the scientific community, of results of these techniques, to accelerate understanding of dynamic high-latitude boundary-processes. The contributions in this work are: (1 improved techniques of analysis of observational data, yielding meaningfully enhanced accuracy for deduced cusp locations; (2 a correspondingly more pronounced validation of correlation of boundary locations derived from the observational data set; and (3 a firmer physical rationale as to why the good correlation observed should theoretically be expected.

    Key words: Ionosphere (ionospheric

  3. Estimation of stable boundary-layer height using variance processing of backscatter lidar data (United States)

    Saeed, Umar; Rocadenbosch, Francesc


    Stable boundary layer (SBL) is one of the most complex and less understood topics in atmospheric science. The type and height of the SBL is an important parameter for several applications such as understanding the formation of haze fog, and accuracy of chemical and pollutant dispersion models, etc. [1]. This work addresses nocturnal Stable Boundary-Layer Height (SBLH) estimation by using variance processing and attenuated backscatter lidar measurements, its principles and limitations. It is shown that temporal and spatial variance profiles of the attenuated backscatter signal are related to the stratification of aerosols in the SBL. A minimum variance SBLH estimator using local minima in the variance profiles of backscatter lidar signals is introduced. The method is validated using data from HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany [2], under different atmospheric conditions. This work has received funding from the European Union Seventh Framework Programme, FP7 People, ITN Marie Curie Actions Programme (2012-2016) in the frame of ITaRS project (GA 289923), H2020 programme under ACTRIS-2 project (GA 654109), the Spanish Ministry of Economy and Competitiveness - European Regional Development Funds under TEC2015-63832-P project, and from the Generalitat de Catalunya (Grup de Recerca Consolidat) 2014-SGR-583. [1] R. B. Stull, An Introduction to Boundary Layer Meteorology, chapter 12, Stable Boundary Layer, pp. 499-543, Springer, Netherlands, 1988. [2] U. Löhnert, J. H. Schween, C. Acquistapace, K. Ebell, M. Maahn, M. Barrera-Verdejo, A. Hirsikko, B. Bohn, A. Knaps, E. O'Connor, C. Simmer, A. Wahner, and S. Crewell, "JOYCE: Jülich Observatory for Cloud Evolution," Bull. Amer. Meteor. Soc., vol. 96, no. 7, pp. 1157-1174, 2015.

  4. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 1; Methods and Comparisons (United States)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Leifer, R.


    This paper examines the aerosol backscattering and extinction profiles measured at night by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site in April 1994. These lidar data are used to derive aerosol profiles for altitudes between 0.0 1 5 and 5 km. Since this lidar detects Raman scattering from nitrogen and oxygen molecules as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously. The aerosol extinction/backscattering ratio varied between approximately 30 sr and 75 sr at 351 nm. Aerosol optical thicknesses derived by integrating the lidar profiles of aerosol extinction measured at night between 0. I and 5 km are found to be about 10-40% lower than those measured by a Sun photometer during the day. This difference is attributed to the contribution by stratospheric aerosols not included in the lidar estimates as well as to diurnal differences in aerosol properties and concentrations. Aerosol profiles close to the surface were acquired by pointing the lidar nearly horizontally. Measurements of aerosol scattering from a tower-mounted nephelometer are found to be 40% lower than lidar measurements of aerosol extinction over a wide range of relative humidities even after accounting for the difference in wavelengths. The reasons for this difference are not clear but may be due to the inability of the nephelometer to accurately measure scattering by large particles.

  5. Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

    Directory of Open Access Journals (Sweden)

    T. Maruyama


    Full Text Available During the SEEK 2 rocket campaign, ionograms were recorded every minute at the Yamagawa Radio Observatory at about 90km west of the region monitored by a VHF (very high frequency coherent backscatter radar. Sporadic E-layer parameters, which include the critical (foEs and blanketing (fbEs frequencies, the layer height (h'Es, and the width of the range spread of sporadic E-traces, were compared with RTI (range-time-intensity plots of VHF quasi-periodic (QP and continuous coherent backscatter echoes. A close relationship was found between the appearance of QP echoes in the RTI plots and the level of spatial inhomogeneity in sporadic E plasma, signified here by the difference between foEs and fbEs. During QP echo events, foEs increased while fbEs decreased, so that the difference foEs-fbEs was enhanced, indicating the development of strong spatial structuring in electron density within a sporadic E-layer. On the other hand, increases in sporadic E range spreading also correlated with the occurrence of QP echoes but the degree of correlation varied from event to event. Continuous radar echoes were observed in association with low altitude sporadic E-layers, located well below 100 km and at times as low as 90 km. During the continuous echo events, both foEs and fbEs were less variable, and the difference foEs-fbEs was small and not as dynamic as in the QP echoes. On the other hand, the Es-layer spread intensified during continuous echoes, which means that some patchiness or corrugation in those low altitude layers is also necessary for the continuous backscatter echoes to take place.

  6. Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar

    Directory of Open Access Journals (Sweden)

    T. Maruyama


    Full Text Available During the SEEK 2 rocket campaign, ionograms were recorded every minute at the Yamagawa Radio Observatory at about 90km west of the region monitored by a VHF (very high frequency coherent backscatter radar. Sporadic E-layer parameters, which include the critical (foEs and blanketing (fbEs frequencies, the layer height (h'Es, and the width of the range spread of sporadic E-traces, were compared with RTI (range-time-intensity plots of VHF quasi-periodic (QP and continuous coherent backscatter echoes. A close relationship was found between the appearance of QP echoes in the RTI plots and the level of spatial inhomogeneity in sporadic E plasma, signified here by the difference between foEs and fbEs. During QP echo events, foEs increased while fbEs decreased, so that the difference foEs-fbEs was enhanced, indicating the development of strong spatial structuring in electron density within a sporadic E-layer. On the other hand, increases in sporadic E range spreading also correlated with the occurrence of QP echoes but the degree of correlation varied from event to event. Continuous radar echoes were observed in association with low altitude sporadic E-layers, located well below 100 km and at times as low as 90 km. During the continuous echo events, both foEs and fbEs were less variable, and the difference foEs-fbEs was small and not as dynamic as in the QP echoes. On the other hand, the Es-layer spread intensified during continuous echoes, which means that some patchiness or corrugation in those low altitude layers is also necessary for the continuous backscatter echoes to take place.

  7. Selection of the ''best'' model for converting beta backscatter count readings into thickness measurements

    International Nuclear Information System (INIS)

    Smiriga, N.G.


    This report compares two models for converting beta backscatter count readings into thickness measurements. The necessary formulas to be used in an unweighted and weighted regression analysis are listed. The question of whether one should perform a regression analysis using the five available standard thicknesses or whether one should, in addition to these standard thicknesses, use zero as a standard thickness is decided. A weighted regression analysis is compared with an unweighted one for each model. The ''best'' model is selected, and the conclusions of the analysis are presented

  8. A Monte-Carlo study of landmines detection by neutron backscattering method

    International Nuclear Information System (INIS)

    Maucec, M.; De Meijer, R.J.


    The use of Monte-Carlo simulations for modelling a simplified landmine detector system with a 252 Cf- neutron source is presented in this contribution. Different aspects and variety of external conditions, affecting the localisation and identification of a buried suspicious object (such as landmine) have been tested. Results of sensitivity calculations confirm that the landmine detection methods, based on the analysis of the backscattered neutron radiation can be applicable in higher density formations, with the mass fraction of present pore-water <15 %. (author)

  9. Characterization of Damage in Magnesium Using Digital Image Correlation and Electron Backscattered Diffraction Patterning (United States)

    Nemcko, Michael J.; Mas, Pauline; Bruhis, Moisei; Wilkinson, David S.

    The microscopic strain distribution of commercially pure magnesium has been investigated during room temperature deformation. Digital image correlation (DIC) coupled with electron backscattered diffraction (EBSD) patterning has been used to relate strain measurements with the microstructure. Sheet magnesium tensile samples were etched and a random pattern of points were machined onto the sample surface using a focused ion beam (FIB). The samples were pulled in tension under an optical microscope. Images were obtained in increments and the DIC method was used to calculate the strain distribution. The strain distribution was compared to the EBSD pattern and the results show that strain localization is associated with twin and grain boundaries.

  10. Backscattering Properties of Nonspherical Ice Particles Calculated by Geometrical-Optics-Integral-Equation Method

    Directory of Open Access Journals (Sweden)

    Masuda Kazuhiko


    Full Text Available Backscattering properties of ice crystal models (Voronoi aggregates (VA, hexagonal columns (COL, and six-branched bullet rosettes (BR6 are calculated by using geometrical-opticsintegral-equation (GOIE method. Characteristics of depolarization ratio (δ and lidar ratio (L of the crystal models are examined. δ (L values are 0.2~0.3 (4~50, 0.3~0.4 (10~25, and 0.5~0.6 (50~100 for COL, BR6, and VA, respectively, at wavelength λ=0.532 μm. It is found that small deformation of COL model could produce significant changes in δ and L.

  11. Development of a backscattering type ultraviolet apertureless near-field scanning optical microscope. (United States)

    Kwon, Sangjin; Jeong, Hyun; Jeong, Mun Seok; Jeong, Sungho


    A backscattering type ultraviolet apertureless near-field scanning optical microscope (ANSOM) for the correlated measurement of topographical and optical characteristics of photonic materials with high optical resolution was developed. The near-field Rayleigh scattering image of GaN covered with periodic submicron Cr dots showed that optical resolution around 40 nm was achievable. By measuring the tip scattered photoluminescence of InGaN/GaN multi quantum wells, the applicability of the developed microscope for high resolution fluorescence measurement was also demonstrated.

  12. Investigating Feasibility Of Multiple UHF Passive RFID Transmitters Using Backscatter Modulation Scheme In BCI Applications

    DEFF Research Database (Denmark)

    Al Ajrawi, Shams; Sarkar, Mahasweta; Rao, Ramesh

    simulatedbrain matter to a receiver located on the surface of a simulatedskull. These analyses are essential for building a brain computerinterface application. We showcase theoretical and experimentalresults based on a phantom model of the human brain usingpassive RFID as the implantable transmitter operating...... in UHFrange. Furthermore, we use backscatter modulation as a powertransfer mechanism. Investigation on the feasibility and appli-cability of implantable UHF Passive RFID transmitters insidethe brain is done for capturing multi-channel ECoG signals at ahigh data transfer rate. Detailed analysis have been done...

  13. Fast and Precise Beam Energy Measurement using Compton Backscattering at e+e- Colliders

    CERN Document Server

    Kaminskiy, V V; Muchnoi, N Yu; Zhilich, V N


    The report describes a method for a fast and precise beam energy measurement in the beam energy range 0.5-2 GeV and its application at various e+e- colliders. Low-energy laser photons interact head-on with the electron or positron beam and produce Compton backscattered photons whose energy is precisely measured by HPGe detector. The method allows measuring the beam energy with relative accuracy of ∼2-5.10-5. The method was successfully applied at VEPP-4M, VEPP-3, VEPP-2000 (BINP, Russia) and BEPC-II (IHEP, China).

  14. Disagreement between capture probabilities extracted from capture and quasi-elastic backscattering excitation functions

    Energy Technology Data Exchange (ETDEWEB)

    Sargsyan, V.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Yerevan State University, Yerevan (Armenia); Adamian, G.G.; Antonenko, N.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Gomes, R.P.S. [Universidade Federal Fluminense, Instituto de Fisica, Niteroi, R.J. (Brazil)


    Experimental quasi-elastic backscattering and capture (fusion) excitation functions are usually used to extract the s -wave capture probabilities for the heavy-ion reactions. We investigated the {sup 16}O + {sup 120}Sn, {sup 144}Sm, {sup 208}Pb systems at energies near and below the corresponding interaction barriers and concluded that the probabilities extracted from quasi-elastic data are much larger than the ones extracted from fusion excitation functions at sub and deep-sub barrier energies. This seems to be a reasonable explanation for the known disagreement observed in the literature for the nuclear potential diffuseness derived from both methods. (orig.)

  15. Application of Rutherford backscattering and nuclear reaction analysis techniques for investigation of thin films

    International Nuclear Information System (INIS)

    Kiss, A.Z.; Simon, A.; Elekes, Z.; Ditroi, F.; Meszaros, S.; Beke, D.L.; Langer, G.A.; Daroczy, L.


    A study of the intermixing of the elements in amorphous Si-Ge multilayers have been carried out using Rutherford backscattering Spectrometry (RBS) technique. Interdiffusion coefficient was determined by measuring the intensity of the first Ge peak (having best depth resolution) in the RBS spectrum as a function of annealing time. The oxygen content of the multilayer was measured by the resonance elastic scattering method in co-operation with Dubna. A cross comparison of multilayered films were performed between the laboratories in Debrecen, Dubna, Albany and Dhaka. An essay to determine the nitrogen content of CVD diamond by the deuteron induced gamma ray emission method has been done. (author)

  16. A Micropulse eye-safe all-fiber molecular backscatter coherent temperature lidar

    DEFF Research Database (Denmark)

    Abari, Cyrus F.; Chu, Xinzhao; Mann, Jakob


    In this paper, we analyze the performance of an all-fiber, micropulse, 1.5 μm coherent lidar for remote sensing of atmospheric temperature. The proposed system benefits from the recent advances in optics/electronics technology, especially an all-fiber image-reject homodyne receiver, where a high...... of this system is the removal of the contaminating Mie backscatter signal by electronic filters at the baseband (before signal conditioning and amplification). The paper presents the basic concepts as well as a Monte-Carlo system simulation as the proof of concept....

  17. Boson peak, flickering noise, backscattering processes and radiative transfer in random media

    International Nuclear Information System (INIS)

    Budak, V.P.; Veklenko, B.A.


    The method of matrix Green's functions in the classical theory of electromagnetic waves is stated. This method allows to obtain a closed equation system in the presence of the random media for the calculation both coherent, and incoherent (fluctuating) components of radiation. The density and heterogeneity of scattering media can be arbitrary. The coherent channel is calculated independently. The fluctuating radiation distribution in the medium is developed initially by an interference pattern generated by the coherent channel. The limitations of the processes speed are absent. The theory embraces such phenomena as the boson peak, flickering noise, memory effect, backscattering processes and also conventional radiative transfer equation and Fresnel's formulae.

  18. Application of the Tor Vergata Scattering Model to L Band Backscatter During the Corn Growth Cycle (United States)

    Joseph, A. T.; vanderVelde, R.; ONeill, P. E.; Lang, R.; Gish, T.


    At the USDA's Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) experimental site in Beltsville, Maryland, USA) a field campaign took place throughout the 2002 corn growth cycle from May 10th (emergence of corn crops) to October 2nd (harvest). One of the microwave instruments deployed was the multi-frequency (X-, C- and L-band) quad-polarized (HH, HV, VV, VH) NASA GSFC/George Washington University (GWU) truck mounted radar. During the field campaign, this radar system provided once a week fully polarized C- and L-band (4.75 and 1.6 GHz) backscatter measurements from incidence angle of 15, 35, and 55 degrees. In support of microwave observations, an extensive ground characterization took place, which included measurements of surface roughness, soil moisture, vegetation biomass and morphology. The field conditions during the campaign are characterized by several dry downs with a period of drought in the month of August. Peak biomass the corn canopies was reached on July 24th with a total biomass of approximately 6.5 kg/sq m. This dynamic range in both soil moisture and vegetation conditions within the data set is ideal for the validation of discrete medium vegetation scattering models. In this study, we compare the L band backscatter measurements with simulations by the Tor Vergata model (ferrazzoli and Guerriero 1996). The measured soil moisture, vegetation biomass and most reliably measured vegetation morphological parameters (e.g. number of leaves, number of stems and stem height) were used as input for the Tor Vergata model. The more uncertain model parameters (e.g. surface roughness, leaf thickness) and the stem diameter were optimized using a parameter estimation routine based on the Levenberg-Marquardt algorithm. As cost function for this optimization, the HH and VV polarized backscatter measured and stimulated by the TOR Vergata model for incidence angle of 15, 35, and 55 degrees were used (6 measurements in total). The calibrated

  19. Materials analysis by ion backscattering and channeling. Materials modification by ion irradiation and implementation

    International Nuclear Information System (INIS)

    Meyer, O.


    A description will be given of the basic processes occuring during ion implantation and ion beam analyses. The usefulness of the backscattering and channeling technique is demonstrated by a discussion of the applications to thin film analysis, studies of diffusion and reactions in thin films, lattice location investigations, disorder analysis and surface studies. Ion implantation is a valuable research tool in metallurgy. The process operates very far from equilibrium conditions and thus will influence near surface properties in a unique way. The observed modifications are related to special microscopic structures which will be considered in detail. (orig.) [de

  20. Jet-Tagged Back-Scattering Photons For Quark Gluon Plasma Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Rainer J., E-mail: [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77845 (United States); De, S. [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77845 (United States); Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata - 700064 (India); Srivastava, D.K. [Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata - 700064 (India)


    Several sources of direct photons are known to contribute to the total photon yield in high energy nuclear collisions. All of these photons carry characteristic and important information on the initial nuclei or the hot and dense fireball created in the collision. We investigate the possibility to separate photons from back-scattering of high momentum quarks off quark gluon plasma from other sources. Their unique kinematics can be utilized through high energy jet triggers on the away-side. We discuss the basic idea and estimate the feasibility of such a measurement at RHIC and LHC.

  1. Nondestructive depth profiling of rare-earth and actinide zeolites via Rutherford backscattering methods

    International Nuclear Information System (INIS)

    Baumann, S.A.; Strathman, M.D.; Suib, S.L.


    Rutherford backscattering (RBS) methods have been used to study rare-earth and actinide-ion-exchanged small pore (A) and large pore (Y) zeolites. A theoretical discussion of the RBS method and a novel method of data treatment are given. Experimental data for zeolites have been simulated and theoretical depth profiles have been determined. Both experimental and theoretical data suggest that uranyl-exchanged A zeolite has a large uranium to oxygen surface ratio while the corresponding Y zeolite has a large uranium to oxygen bulk ratio. Relative atomic fractions of all zeolite elements are also given

  2. The detection of landmines by neutron backscattering: Exploring the limits of the technique

    International Nuclear Information System (INIS)

    Viesti, G.; Lunardon, M.; Nebbia, G.; Barbui, M.; Cinausero, M.; D'Erasmo, G.; Palomba, M.; Pantaleo, A.; Obhodas, J.; Valkovic, V.


    Neutron backscattering (NB) sensors have been proposed for Humanitarian De-mining applications. Recently, a prototype hand-held system integrating a NB sensor in a metal detector has been developed within the EU-funded DIAMINE Project. The results obtained in terms of performance of the NB systems and limitations in its use are presented in this work. It is found that the performance of NB sensors is strongly limited by the presence of the soil moisture and by its small-scale variations. The use of the neutron hit distribution to reduce false alarms is explored

  3. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    Directory of Open Access Journals (Sweden)

    Tsekeri Alexandra


    Full Text Available Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015.

  4. Laser-light backscattering response to water content and proteolysis in dry-cured ham

    DEFF Research Database (Denmark)

    Fulladosa, E.; Rubio-Celorio, M.; Skytte, Jacob Lercke


    Laser backscattering imaging (LBI) is a low-cost technology proposed to determine non-invasively composition and microstructural characteristics of agro food and dairy products. The aim of this work was to define the effect of different acquisition conditions (wavelength, object distance and angle......-cured ham was also evaluated. Results showed that a red laser (635 nm) is more convenient than a green laser (532 nm) to analyse dry-cured ham but no preferable angle or object distance to evaluate dryness or proteolysis was found. Nevertheless, light scattering parameters were modified depending...

  5. Sentinel-1 backscatter sensitivity to vegetation dynamics at the field scale. (United States)

    Vreugdenhil, Mariette; Eder, Alexander; Bauer-Marschallinger, Bernhard; Cao, Senmao; Naeimi, Vahid; Oismueller, Markus; Strauss, Peter; Wagner, Wolfgang


    Vegetation monitoring is pivotal to improve our understanding of the role vegetation dynamics play in the global carbon-, energy- and hydrological cycle. And with the increasing stress on food supply due to the growing world populating and changing climate, vegetation monitoring is of great importance in agricultural areas. By closely tracking crop conditions, droughts and subsequent crop losses could be mitigated. Sensors operating in the microwave domain are sensitive to several surface characteristics, including soil moisture and vegetation. Hence, spaceborne microwave remote sensing provides the means to monitor vegetation and soil conditions on different scales, ranging from field scale to global scale. However, it also presents a challenge since multiple combinations of soil and vegetation characteristics can lead to a similar measurement. Copernicus Sentinel-1 (S-1) is a series of two satellites, developed by the European Space Agency (ESA) , which carry C-band Synthetic Aperture Radars. The C-SAR sensors provide VV, HH, VH and HV backscatter at a 5 m by 20 m spatial resolution. The temporal revisit time of the two satellites is 3-6 days. With their unique capacity for temporally dense and spatially detailed data, the S-1 satellite series provides for the first time the chance to investigate vegetation dynamics at high temporal and spatial resolution. The aim of this study is to assess the sensitivity of Sentinel-1 backscatter to vegetation dynamics. The study is performed in the Hydrological Open Air Laboratory (HOAL), which is a 66 hectare large catchment located in Petzenkirchen, Austria. In the HOAL several vegetation parameters were measured during the course of the growing season (2016) at the overpass time of S-1a. Vegetation height was obtained ten times for the whole catchment, using georeferenced photos made by a motorized paraglider and a Land Surface Model. In addition, vegetation water content, Leaf Area Index and soil moisture were measured in

  6. Modeling loss and backscattering in a photonic-bandgap fiber using strong perturbation (United States)

    Zamani Aghaie, Kiarash; Digonnet, Michel J. F.; Fan, Shanhui


    We use coupled-mode theory with strong perturbation to model the loss and backscattering coefficients of a commercial hollow-core fiber (NKT Photonics' HC-1550-02 fiber) induced by the frozen-in longitudinal perturbations of the fiber cross section. Strong perturbation is used, for the first time to the best of our knowledge, because the large difference between the refractive indices of the two fiber materials (silica and air) makes conventional weak-perturbation less accurate. We first study the loss and backscattering using the mathematical description of conventional surface-capillary waves (SCWs). This model implicitly assumes that the mechanical waves on the core wall of a PBF have the same power spectral density (PSD) as the waves that develop on an infinitely thick cylindrical tube with the same diameter as the PBF core. The loss and backscattering coefficients predicted with this thick-wall SCW roughness are 0.5 dB/km and 1.1×10-10 mm-1, respectively. These values are more than one order of magnitude smaller than the measured values (20-30 dB/km and ~1.5×10-9 mm-1, respectively). This result suggests that the thick-wall SCW PSD is not representative of the roughness of our fiber. We found that this discrepancy occurs at least in part because the effect of the finite thickness of the silica membranes (only ~120 nm) is neglected. We present a new expression for the PSD that takes into account this finite thickness and demonstrates that the finite thickness substantially increases the roughness. The predicted loss and backscattering coefficients predicted with this thin-film SCW PSD are 30 dB/km and 1.3×10-9 mm-1, which are both close to the measured values. We also show that the thin-film SCW PSD accurately predicts the roughness PSD measured by others in a solid-core photonic-crystal fiber.

  7. Analysis of the diffusion in conjugate materials in the superficial region by the ion backscattering method

    International Nuclear Information System (INIS)

    Dhere, N.G.; Vaiude, D.G.; Patnaik, B.K.; Solorzano N, I.G.


    Conjugate materials such as Au/Ti, Au/Pd/Ti, etc are used in semiconductor devices to obtain suitable contact properties. These properties are modified if there is composition variations caused by interdiffusion in the interfaces. The ion backscattering method allows one to obtain the element composition profile along thicknesses down to some microns. The application of this technique for conjugates composed of a gold thin film (approximately 1000 A 0 ) vacuum deposited over titanium substrate is described. The data show the development of Ti-Au interdiffusion from the first stages until the compounds formation. (Author) [pt

  8. Ultrasonic absorption in solid specimens

    International Nuclear Information System (INIS)

    Siwabessy, P.J. W.; Stewart, G.A.


    As part of a project to measure the absorption of high frequency (50 - 500 kHz) sonar signals in warm sea-water, a laboratory apparatus has been constructed and tested against room temperature distilled water and various solutions of MgSO 4 (chemical relaxation of MgSO 4 is the major contribution to absorption below 200 kHz). The technique involves monitoring the decay of an acoustic signal for different sizes of vessels of water suspended in an evacuated chamber. So far, all containing vessels used have been spherical in shape. Extrapolation of the results to infinite volume yields the absorption due to the water alone. In order to accommodate variations in temperature and pressure, and to make the system more robust (e.g. for ship deck usage), it is desirable to employ stainless steel vessels. However, it was found that the quality of the data was greatly improved when pyrex glass spheres were used. The stainless steel spheres were manufactured by welding together mechanically spun hemispheres. The linear frequency dependence characteristic of acoustic absorption in solids was observed (in contrast to the quadratic frequency dependence of acoustic absorption in water), and the acoustic absorption was found to depend strongly on the thermal history of the steel

  9. Detecting changes in ultrasound backscattered statistics by using Nakagami parameters: Comparisons of moment-based and maximum likelihood estimators. (United States)

    Lin, Jen-Jen; Cheng, Jung-Yu; Huang, Li-Fei; Lin, Ying-Hsiu; Wan, Yung-Liang; Tsui, Po-Hsiang


    The Nakagami distribution is an approximation useful to the statistics of ultrasound backscattered signals for tissue characterization. Various estimators may affect the Nakagami parameter in the detection of changes in backscattered statistics. In particular, the moment-based estimator (MBE) and maximum likelihood estimator (MLE) are two primary methods used to estimate the Nakagami parameters of ultrasound signals. This study explored the effects of the MBE and different MLE approximations on Nakagami parameter estimations. Ultrasound backscattered signals of different scatterer number densities were generated using a simulation model, and phantom experiments and measurements of human liver tissues were also conducted to acquire real backscattered echoes. Envelope signals were employed to estimate the Nakagami parameters by using the MBE, first- and second-order approximations of MLE (MLE 1 and MLE 2 , respectively), and Greenwood approximation (MLE gw ) for comparisons. The simulation results demonstrated that, compared with the MBE and MLE 1 , the MLE 2 and MLE gw enabled more stable parameter estimations with small sample sizes. Notably, the required data length of the envelope signal was 3.6 times the pulse length. The phantom and tissue measurement results also showed that the Nakagami parameters estimated using the MLE 2 and MLE gw could simultaneously differentiate various scatterer concentrations with lower standard deviations and reliably reflect physical meanings associated with the backscattered statistics. Therefore, the MLE 2 and MLE gw are suggested as estimators for the development of Nakagami-based methodologies for ultrasound tissue characterization. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Evaluation of Four Supervised Learning Methods for Benthic Habitat Mapping Using Backscatter from Multi-Beam Sonar

    Directory of Open Access Journals (Sweden)

    Jacquomo Monk


    Full Text Available An understanding of the distribution and extent of marine habitats is essential for the implementation of ecosystem-based management strategies. Historically this had been difficult in marine environments until the advancement of acoustic sensors. This study demonstrates the applicability of supervised learning techniques for benthic habitat characterization using angular backscatter response data. With the advancement of multibeam echo-sounder (MBES technology, full coverage datasets of physical structure over vast regions of the seafloor are now achievable. Supervised learning methods typically applied to terrestrial remote sensing provide a cost-effective approach for habitat characterization in marine systems. However the comparison of the relative performance of different classifiers using acoustic data is limited. Characterization of acoustic backscatter data from MBES using four different supervised learning methods to generate benthic habitat maps is presented. Maximum Likelihood Classifier (MLC, Quick, Unbiased, Efficient Statistical Tree (QUEST, Random Forest (RF and Support Vector Machine (SVM were evaluated to classify angular backscatter response into habitat classes using training data acquired from underwater video observations. Results for biota classifications indicated that SVM and RF produced the highest accuracies, followed by QUEST and MLC, respectively. The most important backscatter data were from the moderate incidence angles between 30° and 50°. This study presents initial results for understanding how acoustic backscatter from MBES can be optimized for the characterization of marine benthic biological habitats.

  11. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    KAUST Repository

    Yu, Han


    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green\\'s function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  12. Coherent backscattering effect in spectra of icy satellites and its modeling using multi-sphere T-matrix (MSTM) code for layers of particles (United States)

    Pitman, Karly M.; Kolokolova, Ludmilla; Verbiscer, Anne J.; Mackowski, Daniel W.; Joseph, Emily C. S.


    The coherent backscattering effect (CBE), the constructive interference of light scattering in particulate surfaces (e.g., regolith), manifests as a non-linear increase in reflectance, or opposition surge, and a narrow negative polarization feature at small solar phase angles. Due to a strong dependence of the amplitude and angular width of this opposition surge on the absorptive characteristics of the surface material, CBE also produces phase-angle-dependent variations in the near-infrared spectra. In this paper we present a survey of such variations in the spectra of icy satellites of Saturn obtained by the Cassini spacecraft's Visual and Infrared Mapping Spectrometer (VIMS) and in the ground-based spectra of Oberon, a satellite of Uranus, obtained with TripleSpec, a cross-dispersed near-infrared spectrometer on the Astrophysical Research Consortium 3.5-m telescope located at the Apache Point Observatory near Sunspot, New Mexico. The paper also presents computer modeling of the saturnian satellite spectra and their phase-angle variations using the most recent version of the Multi-Sphere T-Matrix (MSTM) code developed to simulate light scattering by layers of randomly distributed spherical particles. The modeling allowed us not only to reproduce the observed effects but also to estimate characteristics of the icy particles that cover the surfaces of Rhea, Dione, and Tethys.

  13. Improved backscatter x-ray detection for anti-terrorist applications

    International Nuclear Information System (INIS)

    Shope, S.L.; Lockwood, G.J.; Selph, M.M.; Wehlburg, J.C.


    Currently the most common method to determine the contents of a package suspected of containing an explosive device is to use transmission radiography. This technique requires that an x-ray source and film be placed on opposite sides of the package. This poses a problem if the package is placed so that only one side is accessible, such as against a wall. There is also a threat to personnel and property since explosive devices may be booby trapped. The authors have developed a method to x-ray a package using backscattered x-rays based on similar work for landmine detection. This procedure eliminates the use of film behind the target. All of the detection is done from the same side as the source. Backscatter experiments at Sandia National Laboratories have been conducted on mock bombs in packages. They are able to readily identify the bomb components. The images that are obtained in this procedure are done in real time and the image is displayed on a computer screen. Preliminary experiments have also imaged objects within or behind a wall. They are currently using a scanning x-ray source and scintillating plastic detectors. It can take several hours to image a briefcase size object. This time could be reduced if better x-ray detection methods could be used. They have looked at using pinhole photography and CCD cameras to reduce this time

  14. Comparative study of macrotexture analysis using X-ray diffraction and electron backscattered diffraction techniques

    International Nuclear Information System (INIS)

    Serna, Marilene Morelli


    The macrotexture is one of the main characteristics in metallic materials, which the physical properties depend on the crystallographic direction. The analysis of the macrotexture to middles of the decade of 80 was just accomplished by the techniques of Xray diffraction and neutrons diffraction. The possibility of the analysis of the macrotexture using, the technique of electron backscattering diffraction in the scanning electronic microscope, that allowed to correlate the measure of the orientation with its location in the micro structure, was a very welcome tool in the area of engineering of materials. In this work it was studied the theoretical aspects of the two techniques and it was used of both techniques for the analysis of the macrotexture of aluminum sheets 1050 and 3003 with intensity, measured through the texture index 'J', from 2.00 to 5.00. The results obtained by the two techniques were shown reasonably similar, being considered that the statistics of the data obtained by the technique of electron backscatter diffraction is much inferior to the obtained by the X-ray diffraction. (author)

  15. Relation between Raman backscattering from droplets and bulk water: Effect of refractive index dispersion (United States)

    Plakhotnik, Taras; Reichardt, Jens


    A theoretical framework is presented that permits investigations of the relation between inelastic backscattering from microparticles and bulk samples of Raman-active materials. It is based on the Lorentz reciprocity theorem and no fundamental restrictions concerning the microparticle shape apply. The approach provides a simple and intuitive explanation for the enhancement of the differential backscattering cross-section in particles in comparison to bulk. The enhancement factor for scattering of water droplets in the diameter range from 0 to 60 μm (vitally important for the a priori measurement of liquid water content of warm clouds with spectroscopic Raman lidars) is about a factor of 1.2-1.6 larger (depending on the size of the sphere) than an earlier study has shown. The numerical calculations are extended to 1000 μm and demonstrate that dispersion of the refractive index of water becomes an important factor for spheres larger than 100 μm. The physics of the oscillatory phenomena predicted by the simulations is explained.

  16. The impact of ozone field horizontal inhomogeneities on nadir-viewing orbital backscatter UV measurements (United States)

    Mueller, Martin D.; Poli, Paul; Joiner, Joanna


    Radiative transfer calculations for nadir-viewing satellites normally assume the atmosphere to be horizontally homogeneous. Yet it has been shown recently that horizontal gradients can lead to significant errors in satellite infrared and microwave soundings. We extend the methodology to backscatter ultra-violet observations of ozone, and present a first estimate of the effect s magnitude. The Solar Backscatter Ultra-Violet/2 (SBUV/2) instrument, a pure nadir sounder, serves as our test bed. Our results indicate that in a vast majority of cases the abovementioned errors can be neglected. However, occurrence of higher errors, particularly at wavelengths longer than 300 nm, coincides with some of the most interesting atmospheric phenomena like tropopause folds and the South polar ozone hole. This leads to a seasonal variation of the magnitude of the effect. Due to the mostly zonal geometry of the ozone distribution, there is also the possibility that biases may be introduced, which is particularly critical if the data are to be assimilated or used to determine trends. The results presented are tested for robustness using different model atmospheres. The influence of horizontal inhomogeneities will be even more pronounced for cross-track sounders and limb viewers, and easier to detect once higher resolution atmospheric models are available. This will be investigated in future studies.

  17. Reconstruction of chalk pore networks from 2D backscatter electron micrographs using a simulated annealing technique

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, M.S.; Torsaeter, O. [Department of Petroleum Engineering and Applied Geophysics, Norwegian University of Science and Technology, Trondheim (Norway)


    We report the stochastic reconstruction of chalk pore networks from limited morphological information that may be readily extracted from 2D backscatter electron (BSE) images of the pore space. The reconstruction technique employs a simulated annealing (SA) algorithm, which can be constrained by an arbitrary number of morphological descriptors. Backscatter electron images of a high-porosity North Sea chalk sample are analyzed and the morphological descriptors of the pore space are determined. The morphological descriptors considered are the void-phase two-point probability function and lineal path function computed with or without the application of periodic boundary conditions (PBC). 2D and 3D samples have been reconstructed with different combinations of the descriptors and the reconstructed pore networks have been analyzed quantitatively to evaluate the quality of reconstructions. The results demonstrate that simulated annealing technique may be used to reconstruct chalk pore networks with reasonable accuracy using the void-phase two-point probability function and/or void-phase lineal path function. Void-phase two-point probability function produces slightly better reconstruction than the void-phase lineal path function. Imposing void-phase lineal path function results in slight improvement over what is achieved by using the void-phase two-point probability function as the only constraint. Application of periodic boundary conditions appears to be not critically important when reasonably large samples are reconstructed.

  18. Non-Rutherford backscattering microscopy using 25 MeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Peeper, Katrin, E-mail: [Universitaet der Bundeswehr, Angewandte Physik und Messtechnik, Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Moser, Marcus; Reichart, Patrick; Dollinger, Guenther [Universitaet der Bundeswehr, Angewandte Physik und Messtechnik, Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany)


    Protons at energies between 10 and 25 MeV are a very sensitive probe for hydrogen using coincident proton-proton scattering with the possibility for depth profiling samples up to several 100 {mu}m thickness. At the Munich microprobe SNAKE we have developed this method for sensitive 3D hydrogen microscopy . In parallel to sensitive 3D hydrogen microscopy by proton-proton scattering we introduce a non-Rutherford backscattering analysis utilizing 25 MeV protons in order to obtain 3D depth profiles of all major elements. We present energy spectra of backscattered protons at various thin and thick film samples of pure elements which we use as fingerprints to analyse more complex materials like minerals or metals. It is due to the low stopping power of the high energy protons that the depth profiles of several elements do not or do only partially overlap when analysing freestanding samples with thicknesses in the 100 {mu}m range. The merit of our method is that signals of the light elements may not be affected by heavier matrix elements. Analysing thin films smaller than 5 {mu}m we have achieved a mass resolution of {Delta}A/A{<=}1/28 for non-overlapping mass signals utilizing a 5 mm thick Si(Li)-detector.

  19. Material analysis using combined elastic recoil detection and Rutherford/enhanced Rutherford backscattering spectrometry

    International Nuclear Information System (INIS)

    Burkhart, J.H.; Barbour, J.C.


    Three complimentary ion beam techniques will be combined in the analysis of oxide and nitride based materials, in particular BN/SiC and La 0.85 Sr 0.15 CoO 3 . These materials can be synthesized over composition ranges which vary the physical and electrical properties, and therefore an accurate measure of the composition profiles is critical for controlling these properties. Elastic Recoil Detection (ERD) revealed the composition of light elements from H to 0, and Rutherford Backscattering Spectrometry (RBS) gave the composition of heavier elements (e.g., Si, Sr, Co and La). Enhanced Rutherford Backscattering Spectrometry (FRBS) complimented these techniques by utilizing enhanced cross-sections, greater than Rutherford, to increase the signal-to-noise ratio for analysis of mid-range elements 0, C, and N. ERD with 24 MeV Si ions gave profiles for H, B, and N in thin films, and 30 MeV Si was able to profile 0 in the top portion of heavier samples. Although 2.8 MeV He RBS worked well for heavier elements, ERBS utilized He ions at 3.5 MeV for N analysis and 8.7 MeV for 0 analysis, because at these energies the cross sections are 2 and 22 times Rutherford, respectively. Also, the depth of analysis was greater with ERBS because of the increased incident energy

  20. Neutron backscattered application in investigation for Pipeline Intelligent Gauge (PIG) tracking in RAYMINTEX matrix pipeline

    International Nuclear Information System (INIS)

    Mohd Fakarudin Badul Rahman; Ismail Mustapha; Nor Paiza Mohd Hasan; Pairu Ibrahim; Airwan Affandi Mahmood; Mior Ahmad Khusaini Adnan; Najib Mohammed Zakey


    The Radiation Vulcanized Natural Rubber Latex (RVNRL) process plants such RAYMINTEX, pipelines are used extensively to transfer a latex product from storage vessel and being irradiated to produce a high quality of latex. A hydraulically activated Pipeline Intelligent Gauge (PIG) was held back against the latex flow. Consequently, the stuck PIG in pipeline was subjected to interrupt plant operation. The investigation was carried out using the neutron backscattered technique scanner to track the stuck PIG in pipeline of RVNRL plant. The 50 mCi Americium Beryllium (AmBe 241 ) fast neutron emitter source in the range 0.5-11 MeV has been used and thermal neutrons in the 30 eV- 0.5 MeV was detected using Helium-3 (He 3 ) detector. It is observed that there is unambiguous relationship between vapour and RVNRL consequence of diverse hydrogen concentration in pipeline. Thus, neutron backscattered technique was capable to determine the location of stuck PIG in a RVNRL pipeline. (author)

  1. Ultrasound backscatter from free-swimming fish at 1 MHz for fish identification

    DEFF Research Database (Denmark)

    Pham, An Hoai; Lundgren, Bo; Stage, Bjarne


    In the frequency range well below 1 MHz, the swimbladder is often considered the most important part for acoustic fish detection. In this work a portable system was developed to not only detect but also try to identify free-swimming fish. It has been used to measure the ultrasound backscatter at ...... indicate that at 1 MHz the surface areas (also fins and tail) of the fish can give echoes that are much stronger (up to 3 times) than the swimbladder can, therefore important for identification of fish......In the frequency range well below 1 MHz, the swimbladder is often considered the most important part for acoustic fish detection. In this work a portable system was developed to not only detect but also try to identify free-swimming fish. It has been used to measure the ultrasound backscatter at 1...... MHz from fish. The system consists of a Reson TC3210 1 MHz single-element transducer, a dual-frequency, multi-beam Blueview P900-2250 sonar, and three Oregon ATC9K cameras. The Reson transducer is connected to an Olympus pulser-receiver monitored by a portable computer through a Picoscope 4226 PC...

  2. Calculation of low-frequency sound fields in irregular waveguides with strong backscattering (United States)

    Gulin, O. E.


    An approach is developed for calculating the sound fields in a non-stratified sea medium with irregularities that are not weak. The method of cross sections for horizontal parts of acoustic modes is used to obtain first-order causal equations that are equivalent to the boundary-value problem. A matrix equation describing the backscattered field of modes is analyzed, and the conditions that determine the weakness of the irregularities of the medium and the validity of the known approximate methods of sound field calculations are considered. The approximation of unidirectional propagation is represented in the form of quadratures. The example of a 2D shallow-water waveguide with a strongly irregular profile of a perfectly rigid bottom is considered to illustrate the advantages of the proposed approach in comparison with the approximate methods for specific low frequencies. The qualitative and quantitative differences that arise because of taking into account the backscattering between the curves of propagation losses corresponding to the exact solution and the conventional approximate methods are discussed.

  3. Two electric field Monte Carlo models of coherent backscattering of polarized light. (United States)

    Doronin, Alexander; Radosevich, Andrew J; Backman, Vadim; Meglinski, Igor


    Modeling of coherent polarized light propagation in turbid scattering medium by the Monte Carlo method provides an ultimate understanding of coherent effects of multiple scattering, such as enhancement of coherent backscattering and peculiarities of laser speckle formation in dynamic light scattering (DLS) and optical coherence tomography (OCT) diagnostic modalities. In this report, we consider two major ways of modeling the coherent polarized light propagation in scattering tissue-like turbid media. The first approach is based on tracking transformations of the electric field along the ray propagation. The second one is developed in analogy to the iterative procedure of the solution of the Bethe-Salpeter equation. To achieve a higher accuracy in the results and to speed up the modeling, both codes utilize the implementation of parallel computing on NVIDIA Graphics Processing Units (GPUs) with Compute Unified Device Architecture (CUDA). We compare these two approaches through simulations of the enhancement of coherent backscattering of polarized light and evaluate the accuracy of each technique with the results of a known analytical solution. The advantages and disadvantages of each computational approach and their further developments are discussed. Both codes are available online and are ready for immediate use or download.

  4. Imaging near-surface heterogeneities by natural migration of backscattered surface waves: Field data test

    KAUST Repository

    Liu, Zhaolun


    We have developed a methodology for detecting the presence of near-surface heterogeneities by naturally migrating backscattered surface waves in controlled-source data. The near-surface heterogeneities must be located within a depth of approximately one-third the dominant wavelength λ of the strong surface-wave arrivals. This natural migration method does not require knowledge of the near-surface phase-velocity distribution because it uses the recorded data to approximate the Green’s functions for migration. Prior to migration, the backscattered data are separated from the original records, and the band-passed filtered data are migrated to give an estimate of the migration image at a depth of approximately one-third λ. Each band-passed data set gives a migration image at a different depth. Results with synthetic data and field data recorded over known faults validate the effectiveness of this method. Migrating the surface waves in recorded 2D and 3D data sets accurately reveals the locations of known faults. The limitation of this method is that it requires a dense array of receivers with a geophone interval less than approximately one-half λ.

  5. Basic study for ultrasound-based navigation for pedicle screw insertion using transmission and backscattered methods.

    Directory of Open Access Journals (Sweden)

    Ziqiang Chen

    Full Text Available The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation in spinal fusion surgery. Fourteen human vertebral specimens were disarticulated from seven un-embalmed cadavers (four males, three females, 73.14 ± 9.87 years, two specimens from each cadaver. Seven specimens were used to measure the transmission, including tests of attenuation and phase velocity, while the other seven specimens were used for backscattered measurements to inspect the depth of penetration and A-Mode signals. Five pairs of unfocused broadband ultrasonic transducers were used for the detection, with center frequencies of 0.5 MHz, 1 MHz, 1.5 MHz, 2.25 MHz, and 3.5 MHz. As a result, good and stable results were documented. With increased frequency, the attenuation increased (P0.05. At about 0.6 cm away from the cortical bone, warning signals were easily observed from the backscattered measurements. In conclusion, the ultrasonic system proved to be an effective, moveable, and real-time imaging navigation system. However, how ultrasonic navigation will benefit pedicle screw insertion in spinal surgery needs to be determined. Therefore, ultrasound-guided pedicle screw implantation is theoretically effective and promising.

  6. Determination of quality parameters in apple `Smoothee Golden Delicious' using backscattering laser imaging (United States)

    Lafuente, Victoria; Val, Jesús; Urzola, Concha; Negueruela, Ignacio


    The objective of this study was to evaluate in `Smoothee Golden Delicious' apples, the use of backscattering images as a non-destructive method to estimate some quality parameters during the ripening process of fruits. In this experiment, 208 apples were collected from an experimental orchard of the Estación Experimental de Aula Dei (CSIC) in Zaragoza (Northeastern, Spain). Backscattering images were kept from samples picked up every 15 days during 7 months until harvest. In the same fruits, soluble solids contents (SSC) and firmness were measured by traditional destructive methods. The light source was a solid state laser diode module emitting at three different spectral bands (670, 785 and 980 nm) PLS calibration methods were used to create the statistical model to predict SSC and firmness. Good results were obtained when PLS calibration was applied to Feret diameter corresponding at different levels of gray. The Rcv2 values were 0.87 for firmness and 0.93 for SSC, which are higher than other reported in the literature for the same commodity.

  7. Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter (United States)

    Hoge, F. E.; Swift, R. N.


    Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.

  8. A Monte Carlo investigation of saturation thickness and attenuation coefficient for backscattered and transmitted electrons of continuum spectrum

    International Nuclear Information System (INIS)

    Abrahantes, Arian; Diaz, Rafael


    Reliable data on electron backscattering in different media are not available in literature, even more for electrons of continuum spectrum. Material's parameters which depend or could be inferred from those data might have some uncertainties. Back in 1978, K. K. Sharma and M. Singh determined the value of saturation thickness for backscattered electrons and attenuation coefficient in some metals for radioisotopical sources of 90 Sr/ 90 Y and 204 Ti in a particular experimental set up. In this work, new values of those parameters were calculated by Monte Carlo transport of electrons in different materials. The saturation thickness was found to be dependent of the material atomic number and an explanation was proposed to interpret the obtained behavior. Furthermore, results of attenuation coefficient and the saturation thickness differed from those reported by Sharma. It is also mentioned a consideration to Sharma's empirical relation for backscattered intensity of beta particles

  9. Signal Processing and Calibration of Continuous-Wave Focused CO2 Doppler Lidars for Atmospheric Backscatter Measurement (United States)

    Rothermel, Jeffry; Chambers, Diana M.; Jarzembski, Maurice A.; Srivastava, Vandana; Bowdle, David A.; Jones, William D.


    Two continuous-wave(CW)focused C02 Doppler lidars (9.1 and 10.6 micrometers) were developed for airborne in situ aerosol backscatter measurements. The complex path of reliably calibrating these systems, with different signal processors, for accurate derivation of atmospheric backscatter coefficients is documented. Lidar calibration for absolute backscatter measurement for both lidars is based on range response over the lidar sample volume, not solely at focus. Both lidars were calibrated with a new technique using well-characterized aerosols as radiometric standard targets and related to conventional hard-target calibration. A digital signal processor (DSP), a surface acoustic and spectrum analyzer and manually tuned spectrum analyzer signal analyzers were used. The DSP signals were analyzed with an innovative method of correcting for systematic noise fluctuation; the noise statistics exhibit the chi-square distribution predicted by theory. System parametric studies and detailed calibration improved the accuracy of conversion from the measured signal-to-noise ratio to absolute backscatter. The minimum backscatter sensitivity is approximately 3 x 10(exp -12)/m/sr at 9.1 micrometers and approximately 9 x 10(exp -12)/m/sr at 10.6 micrometers. Sample measurements are shown for a flight over the remote Pacific Ocean in 1990 as part of the NASA Global Backscatter Experiment (GLOBE) survey missions, the first time to our knowledge that 9.1-10.6 micrometer lidar intercomparisons were made. Measurements at 9.1 micrometers, a potential wavelength for space-based lidar remote-sensing applications, are to our knowledge the first based on the rare isotope C-12 O(2)-18 gas.

  10. Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation (United States)

    Geisinger, Armin; Behrendt, Andreas; Wulfmeyer, Volker; Strohbach, Jens; Förstner, Jochen; Potthast, Roland


    A new backscatter lidar forward operator was developed which is based on the distinct calculation of the aerosols' backscatter and extinction properties. The forward operator was adapted to the COSMO-ART ash dispersion simulation of the Eyjafjallajökull eruption in 2010. While the particle number concentration was provided as a model output variable, the scattering properties of each individual particle type were determined by dedicated scattering calculations. Sensitivity studies were performed to estimate the uncertainties related to the assumed particle properties. Scattering calculations for several types of non-spherical particles required the usage of T-matrix routines. Due to the distinct calculation of the backscatter and extinction properties of the models' volcanic ash size classes, the sensitivity studies could be made for each size class individually, which is not the case for forward models based on a fixed lidar ratio. Finally, the forward-modeled lidar profiles have been compared to automated ceilometer lidar (ACL) measurements both qualitatively and quantitatively while the attenuated backscatter coefficient was chosen as a suitable physical quantity. As the ACL measurements were not calibrated automatically, their calibration had to be performed using satellite lidar and ground-based Raman lidar measurements. A slight overestimation of the model-predicted volcanic ash number density was observed. Major requirements for future data assimilation of data from ACL have been identified, namely, the availability of calibrated lidar measurement data, a scattering database for atmospheric aerosols, a better representation and coverage of aerosols by the ash dispersion model, and more investigation in backscatter lidar forward operators which calculate the backscatter coefficient directly for each individual aerosol type. The introduced forward operator offers the flexibility to be adapted to a multitude of model systems and measurement setups.

  11. Transdermic absorption of Melagenina II

    International Nuclear Information System (INIS)

    Hernandez Gonzalez, I.; Martinez Lopez, B.; Ruiz Pena, M.; Caso Pena, R.


    The transdermic absorption of Melagenina II (MII) was evaluated. MII was a labelled with 125I by the yodogen method and purified by column chromatography with Sephadex LH-20 in ethanol: water (7:3). In vitro absorption of ( 125I ) - MII thought human skin was carried out in Keshary-Chien modified diffusion cells. Tape stripping method was applied after 24 hours to evaluate the accumulated activity in dermis and epidermis. In vivo assays were performed in Sprague Dawley rats to analyze absorption of MII until 24 hours after a single application and for five days a low penetrability of the drug while in vivo there were not found blood levels significantly greater than zero , nevertheless and important amount of radioactivity was found in feces and urine. The activity was concentrated mainly in the application site in both models

  12. Absorption properties of identical atoms

    International Nuclear Information System (INIS)

    Sancho, Pedro


    Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas. -- Highlights: •The absorption rates of a pair of identical atoms in product and (anti)symmetrized states are different. •The modifications of the optical properties are essentially determined by the overlapping between the atoms. •The absorption properties differ, in some cases, for bosons and fermions

  13. Resonator fiber optic gyro with high backscatter-error suppression using two independent phase-locked lasers (United States)

    Wu, Jiangfeng; Smiciklas, Marc; Strandjord, Lee K.; Qiu, Tiequn; Ho, Waymon; Sanders, Glen A.


    A resonator fiber optic gyro was constructed using separate lasers for counter-rotating waves to overcome interference between optical backscatter and signal light that causes dead-zone behavior and scale factor nonlinearity. This approach enabled a 2 MHz frequency separation between waves in the resonator; eliminating the intended backscatter error. The two lasers were phase-locked to prevent increased gyro noise due to laser frequency noise. Dead-band-free operation near zero-rate, scale factor linearity of 25 ppm and stability of 11 ppm were demonstrated - the closest results to navigation-grade performance reported to date. The approach is also free of impractical frequency shifter technology.

  14. Fine structure of the stimulated Raman spectrum in compressed hydrogen. The relaxation-oscillation mode of backscattered Stokes emission

    International Nuclear Information System (INIS)

    Bespalov, V.G.; Efimov, Yu.N.; Staselko, D.I.


    This paper studies the emission spectra of backscattered stimulated Raman scattering (SRS) in compressed hydrogen in the relaxation-oscillation mode and the compression SRS mode for the minimum width of the spontaneous scattering spectrum (in the region of the Dicke dip). It is shown that the generation of a train of Stokes-emission subpulses results in the appearance of fine structure in the backscattered SRS spectrum. The influence of the temporal structure of reflected Stokes pulses on this spectrum and on the appearance of fine structure in it is analyzed. The conditions for generating spectrally limited (without phase modulation), extremely coherent Stokes pulses are explained. 18 refs., 3 figs

  15. Investigations of effect of target thickness and detector collimation on 662 keV multiply backscattered gamma photons

    International Nuclear Information System (INIS)

    Sabharwal, Arvind D.; Sandhu, B.S.; Singh, Bhajan


    The present studies aimed to investigate the effects of detector collimation and target thickness on multiply backscattered gamma photons. The numbers of multiply backscattered events, having energy the same as in singly scattered distribution, are found to be increasing with target thickness, and saturate for a particular thickness known as saturation thickness. The saturation thickness is not altered by the variation in the collimator opening. The number and energy albedos, characterizing the reflection probability of a material, are also evaluated. Monte Carlo calculations support the present experimental work.

  16. Electric field Monte Carlo simulation of coherent backscattering of polarized light by a turbid medium containing Mie scatterers. (United States)

    Sawicki, John; Kastor, Nikolas; Xu, Min


    A method for directly simulating coherent backscattering of polarized light by a turbid medium has been developed based on the Electric field Monte Carlo (EMC) method. Electric fields of light traveling in a pair of time-reversed paths are added coherently to simulate their interference. An efficient approach for computing the electric field of light traveling along a time-reversed path is derived and implemented based on the time-reversal symmetry of electromagnetic waves. Coherent backscattering of linearly and circularly polarized light by a turbid medium containing Mie scatterers is then investigated using this method.

  17. Backscattering and vegetation water content response of paddy crop at C-band using RISAT-1 satellite data (United States)

    Kumar, Pradeep; Prasad, Rajendra; Choudhary, Arti; Gupta, Dileep Kumar; Narayan Mishra, Varun; Srivastava, Prashant K.


    The study about the temporal behaviour of vegetation water content (VWC) is essential for monitoring the growth of a crop to improve agricultural production. In agriculture, VWC could possibly provide information that can be used to infer water stress for irrigation decisions, vegetation health conditions, aid in yield estimation and assessment of drought conditions (Penuelas et al., 1993). The VWC is an important parameter for soil moisture retrieval in microwave remote sensing (Srivastava et al., 2014). In the present study, the backscattering and VWC response of paddy crop has been investigated using medium resolution (MRS) radar imaging satellite-1 (RISAT-1) synthetic aperture radar (SAR) data in Varanasi, India. The VWC of paddy crop was measured at its five different growth stages started from 15 July 2013 to 23 October 2013 from the transplanting to maturity stage during Kharif season. The whole life of paddy crop was divided into three different major growth stages like vegetative stage, reproductive stage and ripening stage. During vegetative stage, the backscattering coefficients were found increasing behaviour until the leaves became large and dense due to major contribution of stems and the interaction between the stems and water underneath the paddy crop. During reproductive stage, the backscattering coefficients were found to increase slowly due to random scattering by vertical leaves. The increase in the size of leaves cause to cover most of the spaces between plants resulted to quench the contributions from the stems and the water underneath. At the maturity stage, the backscattering showed its decreasing behaviour. The VWC of paddy crop was found increasing up to vegetative to reproductive stages (28 September 2013) and then started decreasing during the ripening (maturity) stage. Similar behaviour was obtained between backscattering coefficients and VWC that showed an increasing trend from vegetative to reproductive stage and then lowering down at

  18. Calibrating a ground-based backscatter lidar for continuous measurements of PM2.5 (United States)

    Pesch, Markus; Oderbolz, Daniel


    One of the main issues of atmospheric research and air quality control is the reduction of harmful particulate matter (PM) in the atmosphere. Small particles can enter the human airways and cause serious health problems such as COPD (Chronic Obstructive Pulmonary Disease), asthma or even lung cancer. Recently, interest has shifted from PM10 to finer fractions of particulate matter, e.g. PM2.5, because the health impact of finer particles is considered to be more severe. Up to now measurements of particulate matter were carried out mainly at ground level. However important atmospheric processes, i.e. particle formation, transport and vertical mixing processes, take place predominantly at higher altitudes in the planetary boundary layer. Lidar in principle provides the ability to observe these processes where they occur. The new method outlined in this paper demonstrates the use of a small sized and quite inexpensive lidar in stand-alone operation to investigate transport processes of particulate matter, and PM2.5 in particular. Continuous measurements of PM2.5 as a reference are gained with a conventional in-situ monitor, installed on a tower at an altitude of 325 m in the North of Berlin (Frohnauer Turm). These PM2.5 measurements will be compared with backscatter Lidar data (1064 nm) taken from approx. 60 m over ground up to an altitude of 15 km with a spatial resolution of 15 m. The vertical backscatter profiles at 325 m will be correlated to the concentrations obtained by the PM2,5 monitor on the tower. Both measurements have a time resolution of 180 s to observe also processes that take place at short time scales. The objective is to gain correlation functions for estimating PM2.5 concentrations from backscatter Lidar data. Such a calibrated Lidar system is a valuable instrument for environmental agencies and atmospheric research groups to observe and investigate causes of high level PM concentrations. First results show a reasonably good linear correlation

  19. Application of the gamma rays backscattering for determining the quantity of steel

    International Nuclear Information System (INIS)

    Huapaya P, B.F.


    This work tries to purpose a methodology based on the nuclear technology available in the country, for measuring the position and diameter of the reinforcing rods placed in reinforced concrete structures. The technique of gamma backscattering that utilizes the changes of density was used for determining the presence of steel (average density of concrete 2,5 g/cm 3 and steel 7,8 g/cm 3 ). The concrete test tubes of different resistances were prepared with diverse concentrations into the aggregates as crushed rock and coarse sand, and also with three steel rods of 0,5 inch separated by 4 inches among themselves. The source Cs-137 of 20 mCi in activity was a monoenergetic radioisotope of the element Cs from 662 KeV. The source was placed in a lead shield with a hole which generates a collimator beam of 2 mm. The detector was one type of scintillation (INa-Tl) 2 x 2 inch; it was sealed with lead and had a hole of 10 mm which worked as collimator. The shield was placed in an angle of 15 degrees over concrete surface in order to pick up the backscattering gamma rays by the concrete. The test tube was displaced over a little car affixed to a endless screw which permitted to reproduce displacements of 0,25 inch. The data recording was realized through a multichannel of 1024 channels where was accounted the number of counts viewed under the backscattering spectrum by the concrete. It is possible to determine the position and diameter of the steel rod into concrete, changing the parameters of detector collimator source, distance source-detector and type of concrete. Furthermore, it was shown that this same equipment can measure the density of the concrete. The applications of this equipment are used in the inspection works where it is necessary to make a non-destructive control of quality about the structure of building. (author). 7 refs., 46 tabs., 24 figs

  20. Aerosol Absorption Measurements in MILAGRO. (United States)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.


    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  1. Sound absorption property of openpore aluminum foams


    WANG Fang; WANG Lu-cai; WU Jian-guo


    This paper presents a study on sound absorption property of aluminum foam by evaluating its sound absorption coefficients using standing wave tube method. Experimental results showed that the average values of sound absorption coefficients (over the test frequency range) are all above 0.4, which indicate very good sound absorption property of the aluminum foams. The sound absorption coefficient is affected by frequency and pore structure, and reaches its maximum value at around 1 000 Hz. With...

  2. Bent Electro-Absorption Modulator

    DEFF Research Database (Denmark)


    components and the applied electric field in relation to the frequency of the modulated radiation, the bending losses (and possibly coupling losses) will provide extinction of light guided by the bent waveguide section. The refractive index contract may be modulated while keeping the absorption coefficient...... by bendng losses co-operates to provide more compact modulators with improved performance (extinction) and speed....


    African Journals Online (AJOL)


    Three commonly used techniques, namely atomic absorption spectrophotometry (AAS-Ashing and. AAS-Non Ashing) and titrimetry (potassium permanganate titration) have been evaluated in this study to determine the calcium content in six food samples whose calcium levels ranged from 0 to more than. 250mg/100g ...

  4. A simple way to obtain backscattered electron images in a scanning transmission electron microscope. (United States)

    Tsuruta, Hiroki; Tanaka, Shigeyasu; Tanji, Takayoshi; Morita, Chiaki


    We have fabricated a simple detector for backscattered electrons (BSEs) and incorporated the detector into a scanning transmission electron microscope (STEM) sample holder. Our detector was made from a 4-mm(2) Si chip. The fabrication procedure was easy, and similar to a standard transmission electron microscopy (TEM) sample thinning process based on ion milling. A TEM grid containing particle objects was fixed to the detector with a silver paste. Observations were carried out using samples of Au and latex particles at 75 and 200 kV. Such a detector provides an easy way to obtain BSE images in an STEM. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail:

  5. Application of Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS) for the investigation of midlatitude ionospheric irregularities (United States)

    Wang, Jin; Zhou, Xiaoming; Qiao, Lei; Gong, Wanlin


    An upgrade of Wuhan Ionospheric Backscattering Sounding System (WIOBSS) was developed in 2015. Based on the Universal Serial Bus (USB), and a high performance FPGA, the newly designed WIOBSS has a completely digital structure, which makes it portable and flexible. Two identical WIOBSSs, which were situated at Mile (24.31°N, 103.39°E) and Puer (22.74°N, 101.05°E) respectively, were used to investigate the ionospheric irregularities. The comparisons of group distance, Doppler shift and width between Mile-Puer and Puer-Mile VHF ionospheric propagation paths indicate that the reciprocity of the irregularities is satisfied at midlatitude region. The WIOBSS is robust in the detection of ionospheric irregularities.

  6. Wuhan Ionospheric Oblique Backscattering Sounding System and Its Applications-A Review. (United States)

    Shi, Shuzhu; Yang, Guobin; Jiang, Chunhua; Zhang, Yuannong; Zhao, Zhengyu


    For decades, high-frequency (HF) radar has played an important role in sensing the Earth's environment. Advances in radar technology are providing opportunities to significantly improve the performance of HF radar, and to introduce more applications. This paper presents a low-power, small-size, and multifunctional HF radar developed by the Ionospheric Laboratory of Wuhan University, referred to as the Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS). Progress in the development of this radar is described in detail, including the basic principles of operation, the system configuration, the sounding waveforms, and the signal and data processing methods. Furthermore, its various remote sensing applications are briefly reviewed to show the good performance of this radar. Finally, some suggested solutions are given for further improvement of its performance.

  7. Effects of Hot-Spot Geometry on Backscattering and Down-Scattering Neutron Spectra (United States)

    Mohamed, Z. L.; Mannion, O. M.; Forrest, C. J.; Knauer, J. P.; Anderson, K. S.; Radha, P. B.


    The measured neutron spectrum produced by a fusion experiment plays a key role in inferring observable quantities. One important observable is the areal density of an implosion, which is inferred by measuring the scattering of neutrons. This project seeks to use particle-transport simulations to model the effects of hot-spot geometry on backscattering and down-scattering neutron spectra along different lines of sight. Implosions similar to those conducted at the Laboratory of Laser Energetics are modeled by neutron transport through a DT plasma and a DT ice shell using the particle transport codes MCNP and IRIS. Effects of hot-spot geometry are obtained by ``detecting'' scattered neutrons along different lines of sight. This process is repeated for various hot-spot geometries representing known shape distortions between the hot spot and the shell. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  8. Trace element determination in tomato puree using particle induced X-ray emission and Rutherford backscattering

    International Nuclear Information System (INIS)

    Romero-Davila, E.; Miranda, J.


    Particle induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were used to determine the concentrations of trace elements in samples of 12 tomato puree brands sold in the Mexican market. While RBS offered information about the main elements present in the matrix, PIXE gave results on trace elements. As a whole, data for 17 elements (C, N, O, Na, Mg, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn) were obtained. To evaluate the results, a comparison with brands from USA, Japan, Colombia, and Chile was carried out, using tomato purees produced following the domestic technology recipe. Additionally, the results were considered in the light of the Codex Alimentarius and the Mexican standard. It was found that all of the brands fall within the limits established by these standards, being of the same order of magnitude as the foreign brands. (author)

  9. Uniform light distribution in hollow organs by means of backscattering layers (United States)

    Beyer, Wolfgang; Baumgartner, Reinhold; Ell, Christian; Heinze, Armin; Jocham, Dieter; Sroka, Ronald; Stepp, Herbert G.; Unsoeld, Eberhard


    The uniform distribution of light over the area to be photodynamically treated is one of the prerequisites for a successful tumor therapy. For homogenization of laser light distributions especially in hollow organs a new method has been developed. It applies fiber coupled emitters in combination with a highly backscattering layer deposited on the inner wall of the organ to be irradiated. The effect of homogenization by means of this layer has been calculated for spherical and cylindrical hollow organs and compared with experimental results. This method also seems to be applicable for organs with irregular geometry. Laser light applications for different medical fields will be described. Applying the same method, isotropic light detectors with diameters of less than 1 mm have been developed for irradiation control during photodynamic treatment or for determination of light distributions in tissue.

  10. Design and investigation of sectoral circular disc monopole fractal antenna and its backscattering

    Directory of Open Access Journals (Sweden)

    Raj Kumar


    Full Text Available This article presents the design of sectoral circular disc fractal antenna. The proposed antenna has been excited using CPW – feed. The measured result of this antenna offers the ultra wideband characteristics from 3.265 GHz to 15.0 GHz. The measured and simulated results are compared and found in good agreement. The impedance match of the antenna throughout the band is improved by incorporating the rectangular slots in the ground plane. The measured radiation patterns of this antenna are nearly omni-directional in H-plane and bidirectional in E-plane. The backscattering of antenna is also discussed and calculated for antenna mode and structural mode scattering. This type of antenna is useful for UWB system, microwave imaging and vehicular radar, precision positioning location.

  11. Lead foil in dental X-ray film: Backscattering rejection or image intensifier?

    Energy Technology Data Exchange (ETDEWEB)

    Hönnicke, M.G., E-mail: [Universidade Federal da Integração Latino-Americana, Foz do Iguaçu (Brazil); Delben, G.J. [Faculdade de Tecnologia Tupy, Curitiba (Brazil); Godoi, W.C. [Universidade Tecnológica Federal do Paraná, Curitiba (Brazil); Swinka-Filho, V. [Instituto de Tecnologia para o Desenvolvimento – LACTEC, Curitiba (Brazil)


    Dental X-ray films are still largely used due to sterilization issues, simplicity and, mainly, economic reasons. These films almost always are double coated (double emulsion) and have a lead foil in contact with the film for X-ray backscattering rejection. Herein we explore the use of the lead foil as an image intensifier. In these studies, spatial resolution was investigated when images were acquired on the dental X-ray films with and without the lead foil. Also, the lead foil was subjected to atomic analysis (fluorescent measurements) and structure analysis (X-ray diffraction). We determined that the use of the lead foil reduces the exposure time, however, does not affect the spatial resolution on the acquired images. This suggests that the fluorescent radiation spread is smaller than the grain sizes of the dental X-ray films.

  12. Elastic and inelastic surface effects on ion penetration and the resulting sputtering and backscattering

    International Nuclear Information System (INIS)

    Hassanein, A.M.; Smith, D.L.


    The computer code ITMC (Ion Transport in Materials and Compounds) has been developed to study in detail the transport of charged particles in solid materials and surface related phenomena such as sputtered atoms and backscattered ions. The code is based on Monte Carlo methods to follow the path and the damage produced by the charged particles in three dimension as they slow down in target materials. Single-element targets as well as alloys with possible different surface and bulk compositions or with layered structures of different materials can be used. Various models developed to calculate the inelastic energy losses with target electrons can be used in the code. Most known interatomic potentials can also be used to calculate the elastic energy losses. The major advantages of the code are its ability and flexibility to use and compare various models of elastic and inelastic energy losses in any target with different compounds and different surface and bulk composition

  13. A Micropulse eye-safe all-fiber molecular backscatter coherent temperature lidar

    Directory of Open Access Journals (Sweden)

    Abari Cyrus F.


    Full Text Available In this paper, we analyze the performance of an all-fiber, micropulse, 1.5 μm coherent lidar for remote sensing of atmospheric temperature. The proposed system benefits from the recent advances in optics/electronics technology, especially an all-fiber image-reject homodyne receiver, where a high resolution spectrum in the baseband can be acquired. Due to the presence of a structured spectra resulting from the spontaneous Rayleigh-Brillouine scattering, associated with the relevant operating regimes, an accurate estimation of the temperature can be carried out. One of the main advantages of this system is the removal of the contaminating Mie backscatter signal by electronic filters at the baseband (before signal conditioning and amplification. The paper presents the basic concepts as well as a Monte-Carlo system simulation as the proof of concept.

  14. A Compact, Backscattering Deplolarization Cloud Spectrometer for Ice and Water Discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, David


    This project was to develop a compact optical particle spectrometer, small enough for operation on UAVS, that measures the optical diameter of cloud hydrometeors and differentiates their water phase (liquid or solid). To reach this goal, a work plan was laid out that would complete three objectives: 1) Evaluation of designs for an optical particle spectrometer that measures the component of light backscattered at two polarization angles. 2) Testing of selected designs on an optical bench. 3) Construction and preliminary testing of a prototype instrument based on the selected, optimum design. A protoype instrument was developed and tested in an icing wind tunnel where the results showed good measurement of cloud droplets and ice particles.

  15. A flying spot x-ray system for Compton backscatter imaging

    International Nuclear Information System (INIS)

    Herr, M.D.; McInerney, J.J.; Copenhaver, G.L.; Lamser, D.G.


    A Compton x-ray backscatter imaging (CBI) system using a single detector and a mechanically rastered ''flying spot'' x-ray beam has been designed, built, and tested. While retaining the essential noninvasive imaging capability of previous multiple detector CBI devices, this single detector system incorporates several advances over earlier CBI devices: more efficient detection of scattered x-rays, reduced x-ray exposure, and a simplified scan protocol more suitable for use with humans. This new CBI system also has specific design features to permit automating data acquisition from multiple two-dimensional image planes for integration into a 3-D dynamic surface image. A simulated multislice scan study of a human thorax phantom provided x-ray dosimetry data verifying a very low x-ray dose delivered by this imaging device. Validation experiments with mechanical models show that surface displacement of typical heart beam frequencies can be measured to the nearest 0.1 mm (SD)

  16. Point-spread functions for backscattered imaging in the scanning electron microscope (United States)

    Hennig, Philipp; Denk, Winfried


    One knows the imaging system's properties are central to the correct interpretation of any image. In a scanning electron microscope regions of different composition generally interact in a highly nonlinear way during signal generation. Using Monte Carlo simulations we found that in resin-embedded, heavy metal-stained biological specimens staining is sufficiently dilute to allow an approximately linear treatment. We then mapped point-spread functions for backscattered-electron contrast, for primary energies of 3 and 7 keV and for different detector specifications. The point-spread functions are surprisingly well confined (both laterally and in depth) compared even to the distribution of only those scattered electrons that leave the sample again.

  17. Backscatter analysis of dihedral corner reflectors using physical optics and the physical theory of diffraction (United States)

    Griesser, Timothy; Balanis, Constantine A.


    The backscatter cross-sections of dihedral corner reflectors in the azimuthal plane are presently determined by both physical optics (PO) and the physical theory of diffraction (PTD), yielding results for the vertical and horizontal polarizations. In the first analysis method used, geometrical optics is used in place of PO at initial reflections in order to maintain the planar character of the reflected wave and reduce the complexity of the analysis. In the second method, PO is used at almost every reflection in order to maximize the accuracy of the PTD solution at the expense of a rapid increase in complexity. Induced surface current densities and resulting cross section patterns are illustrated for the two methods.

  18. Total electron count variability and stratospheric ozone effects on solar backscatter and LWIR emissions (United States)

    Ross, John S.; Fiorino, Steven T.


    The development of an accurate ionospheric Total Electron Count (TEC) model is of critical importance to high frequency (HF) radio propagation and satellite communications. However, the TEC is highly variable and is continually influenced by geomagnetic storms, extreme UV radiation, and planetary waves. Being able to capture this variability is essential to improve current TEC models. The growing body of data involving ionospheric fluctuations and stratospheric variations has revealed a correlation. In particular, there is a marked and persistent association between increases in stratospheric ozone and variability of the TEC. The spectral properties of ozone show that it is a greenhouse gas that alters long wave emissions from Earth and interacts with the UV spectrum coming from the sun. This study uses the Laser Environment Effects Definition and Reference (LEEDR) radiative transfer and atmospheric characterization code to model the effects of changes in stratospheric ozone on solar backscatter and longwave (LWIR) terrestrial emissions and infer TEC and TEC variability.

  19. Stratospheric Smoke With Unprecedentedly High Backscatter Observed by Lidars Above Southern France (United States)

    Khaykin, S. M.; Godin-Beekmann, S.; Hauchecorne, A.; Pelon, J.; Ravetta, F.; Keckhut, P.


    Extreme pyroconvection events triggered by wildfires in northwest Canada and United States during August 2017 resulted in vast injection of combustion products into the stratosphere. The plumes of stratospheric smoke were observed by lidars at Observatoire de Haute-Provence (OHP) for many weeks that followed the fires as distinct aerosol layers with backscatter reaching unprecedentedly high values for a nonvolcanic aerosol layer. We use spaceborne CALIOP lidar to track the spatiotemporal evolution of the smoke plumes before their detection at OHP. A remarkable agreement between ground- and spaced-based lidars sampling the same smoke plume on a particular date allowed us to extrapolate the OHP observations to a regional scale, where CALIOP reported extreme aerosol optical depth values as high as 0.21. On a monthly time scale, the lidar observations indicate that boreal summer 2017 forest fires had a hemisphere-scale impact on stratospheric aerosol load, similar to that of moderate volcanic eruptions.

  20. Backscattered electron emission after proton impact on carbon and gold films: Experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hespeels, F.; Heuskin, A.C. [University of Namur, PMR, 61 rue de Bruxelles, B-5000 Namur (Belgium); Scifoni, E. [TIFPA-INFN, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento (Italy); GSI-Helmholtzzentrum für Schwerionenforschung, Biophysik, Max Planck-Strasse 1, D-64291 Darmstadt (Germany); Kraemer, M. [GSI-Helmholtzzentrum für Schwerionenforschung, Biophysik, Max Planck-Strasse 1, D-64291 Darmstadt (Germany); Lucas, S., E-mail: [University of Namur, PMR, 61 rue de Bruxelles, B-5000 Namur (Belgium)


    This work aims at measuring the proton induced secondary electron energy spectra from nanometer thin films. Backscattered electron energy spectra were measured within an energy range from 0 to 600 eV using a Retarding Field Analyser (RFA). This paper presents energy spectra obtained for proton (0.5 MeV; 1 MeV; 1.5 MeV; 2 MeV) irradiation of thin carbon films (50 and 100 nm thick) and thin gold film (200 nm). These experimental spectra were compared with Monte Carlo simulations based on TRAX code and Geant4 simulation toolkit. Good agreement between experimental, TRAX and Geant4 results were observed for the carbon target. For the gold target, we report major differences between both Monte Carlo environments. Limitation of Geant4 models for low energy electron emission was highlighted. On the contrary, TRAX simulations present encouraging results for the modeling of low-energy electron emission from gold target.

  1. Two and three dimensional electron backscattered diffraction analysis of solid oxide cells materials

    DEFF Research Database (Denmark)

    Saowadee, Nath

    structure. In this case, lattice parameters analysis aid to differential the secondary phases. However lattice constant of secondary phase cannot measure by general tools such as x-ray diffraction due to its insufficiency. Point analysis in electron backscattered diffraction (EBSDX allows measuring......There are two main technique were developed in this work: a technique to calculate grain boundary energy and pressure and a technique to measure lattice constant from EBSD. The techniques were applied to Nb-doped Strontium titanate (STN) and yttria stabilized zirconia (YSZ) which are commonly used...... sectioning. Band contrast and band slope were used to describe the pattern quality. The FIB probe currents investigated ranged from 100 to 5000 pA and the accelerating voltage was either 30 or 5 kV. The results show that 30 kV FIB milling induced a significant reduction of the pattern quality of STN samples...

  2. Adaptive characterization of recrystallization kinetics in IF steel by electron backscatter diffraction. (United States)

    Kim, Dong-Kyu; Park, Won-Woong; Lee, Ho Won; Kang, Seong-Hoon; Im, Yong-Taek


    In this study, a rigorous methodology for quantifying recrystallization kinetics by electron backscatter diffraction is proposed in order to reduce errors associated with the operator's skill. An adaptive criterion to determine adjustable grain orientation spread depending on the recrystallization stage is proposed to better identify the recrystallized grains in the partially recrystallized microstructure. The proposed method was applied in characterizing the microstructure evolution during annealing of interstitial-free steel cold rolled to low and high true strain levels of 0.7 and 1.6, respectively. The recrystallization kinetics determined by the proposed method was found to be consistent with the standard method of Vickers microhardness. The application of the proposed method to the overall recrystallization stages showed that it can be used for the rigorous characterization of progressive microstructure evolution, especially for the severely deformed material. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

  3. High resolution electron backscatter diffraction (EBSD) data from calcite biominerals in recent gastropod shells. (United States)

    Pérez-Huerta, Alberto; Dauphin, Yannicke; Cuif, Jean Pierre; Cusack, Maggie


    Electron backscatter diffraction (EBSD) is a microscopy technique that reveals in situ crystallographic information. Currently, it is widely used for the characterization of geological materials and in studies of biomineralization. Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. Overall, the usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is discussed as well as its application to similar studies. © 2010 Elsevier Ltd. All rights reserved.

  4. Rutherford Backscattering and Channeling Studies of Al and Mg Diffusion in Iron Oxide Thin Films

    International Nuclear Information System (INIS)

    Thevuthasan, Theva; McCready, David E.; Jiang, Weilin; Mcdaniel, Emily P.; Yi, Sang I.; Chambers, Scott A.; J.L. Duggan and I.L. Morgan


    Thin films of alpha-Fe2O3(0001) (hermatite) and gamma-Fe2O3 (001) (maghemite) were epitaxially grown on Al2O3(0001) substrates, respectively, using the new molecular beam epitaxy (MBE) system at the Environmental Molecular Sciences Laboratory (EMSL). We have investigated the crystalline quality of these films using Rutherford Backscattering (RBS) and channeling experiments. Minimum yields obtained from aligned and random spectra are 2.7+-0.3% for the alpha-Fe2o3(0001) film and 14.5+-0.6% for the gamma-Fe2O3 (001) film. Al and Mg outdiffusion into the hematite and maghemite films were observed at higher temperatures. Indiffusion of Fe atoms from the film into the substrate was observed for the gamma-Fe2o3(001)/MgO(001) system. In contrast, no Fe indiffusion was observed for the sapphire substrate

  5. Mechanism of synchronized change in ultrasonic integrated backscatter across human heart wall (United States)

    Tobinai, Yumi; Taki, Hirofumi; Kanai, Hiroshi


    Ultrasonic integrated backscatter (IB) from the heart wall, which has been employed for quantitative tissue characterization of the myocardium, is known to have cyclic variation-a decrease in systole and an increase in diastole. In the present study, by tracking the measurement position of the myocardium and compensating for the movement due to the heartbeat, IB and its temporal variation were obtained from the same site with a high temporal resolution of 1.73 ms. In an in vivo study on a healthy subject, the temporal variation of IB values homogeneously changed across the heart wall, especially during the slow filling and the atrial systole phases. This new finding shows that the IB value reflects a small movement of the myocardium of about 5 mm/s. Thus, the proposed measurement has a potential for quantitative and accurate evaluation of the contraction and relaxation of the myocardium.

  6. Evaluation of density, moisture content and percentage compaction of concrete using direct transmission and backscatter methods

    International Nuclear Information System (INIS)

    Attobrah, A. T


    The nuclear method widely used in determining the density and moisture content of soil - aggregates, asphalt concretes, roller compacted concretes and Portland cement concretes, is the radiometry technique. Generally, all radiometry systems consist of a source of radiation, the sample being examined and a radiation detector. In operation, a radioactive source and a detector are placed on the same or opposite sides of a concrete sample. A portion of radiation from the source which passes through the concrete sample and reaches the detector produces a series of electrical pulses which when counted gives a measure of the dimensions or physical characteristics of the concrete sample. In this research work, concrete beams were fabricated using a 500 x 225 x 200mm wooden mould whiles a table vibrator was used to consolidate the concrete after placement in the mould. The mass of the beam was determined and the actual density calculated and inputted in the gauge. Measurements were performed on the unhardened and hardened concrete using the backscatter method and the direct transmission method at depths of 50mm, 100mm and 150mm. The measuring times of 15, 60 and 240 second were use to take the measurements. The study provided information on the variation of density with depth and this was observed to be within the range of 0 kg/m 3 to 1 kg/m 3 and 13 kg/m 3 to 23 kg/m 3 for the unhardened concrete samples in which density increased with depth and those in which density decreased with depth respectively. For the hardened concrete sample, the average change in density with depth was between 4 - 11 kg/m 3 for the samples in which density increased with depth and between 11 - 21 kg/m 3 for the samples in which density decreased with depth. The study also provided information about the degree of consolidation of Portland cement concrete which on the average was between 95% - 97% for the unhardened concrete samples and increased to between 97% - 99% for the hardened concrete

  7. Estimating sub-surface dispersed oil concentration using acoustic backscatter response. (United States)

    Fuller, Christopher B; Bonner, James S; Islam, Mohammad S; Page, Cheryl; Ojo, Temitope; Kirkey, William


    The recent Deepwater Horizon disaster resulted in a dispersed oil plume at an approximate depth of 1000 m. Several methods were used to characterize this plume with respect to concentration and spatial extent including surface supported sampling and autonomous underwater vehicles with in situ instrument payloads. Additionally, echo sounders were used to track the plume location, demonstrating the potential for remote detection using acoustic backscatter (ABS). This study evaluated use of an Acoustic Doppler Current Profiler (ADCP) to quantitatively detect oil-droplet suspensions from the ABS response in a controlled laboratory setting. Results from this study showed log-linear ABS responses to oil-droplet volume concentration. However, the inability to reproduce ABS response factors suggests the difficultly in developing meaningful calibration factors for quantitative field analysis. Evaluation of theoretical ABS intensity derived from the particle size distribution provided insight regarding method sensitivity in the presence of interfering ambient particles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Measurement of the BESSY II electron beam energy by Compton-backscattering of laser photons

    CERN Document Server

    Klein, R; Thornagel, R; Brandt, G; Görgen, R; Ulm, G


    Accurate knowledge of all storage ring parameters is essential for the Physikalisch-Technische Bundesanstalt (PTB) to operate the electron storage ring BESSY II as a primary source standard. One parameter entering the Schwinger equation for the calculation of the spectral photon flux of bending magnet radiation is the electron beam energy. So at BESSY II the electron beam energy is measured by two independent techniques one of which is described in this paper: the photons from a CO sub 2 -laser are scattered in a head-on collision with the stored electrons. From the spectrum of the backscattered photons that are detected by an energy-calibrated HPGe detector the electron beam energy can be determined. The experimental set-up at the BESSY II electron storage ring as well as the current experimental status are described for operation of the storage ring at the energies of 900 and 1700 MeV.

  9. Analysis of the dehydration process of caffeine using backscattering and transmission Raman spectroscopy. (United States)

    Takeshima, Rina; Hattori, Yusuke; Managaki, Satoshi; Otsuka, Makoto


    In the present study, the dehydration process of caffeine hydrate (CAH) was investigated by calibrating the moisture content in the caffeine tablet using backscattering Raman spectroscopy (BRS) and transmission Raman spectroscopy (TRS). The detectable depth of BRS is limited by its shallow laser penetration, while TRS is a powerful tool to determine the content of active pharmaceutical ingredients in a tablet. Our results suggest that the accuracy of a TRS-based calibration model falls beyond that of a BRS-based model. Based on the calibration used, the model was built by calculating the differences in the crystalline structures between hydrate and anhydrous caffeine. Moreover, it was demonstrated that the dehydration process occurred by switching water molecules between hydration sites of caffeine. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Analysis of the performance of a coherent pulsed fiber lidar for aerosol backscatter applications. (United States)

    Pearson, Guy N; Roberts, P John; Eacock, Justin R; Harris, Michael


    The antenna and the Doppler estimation characteristics of a coherent pulsed lidar intended for short-range aerosol backscatter applications have been analyzed. The system used fiber-optic interconnects and operated at a wavelength of 1.548 microm. The range dependence of the signal for various bistatic and monostatic antenna configurations has been determined. The system operated in a low-pulse-energy, high-pulse-repetition-rate mode, and the Doppler estimates from the return signal were achieved with a multipulse accumulation procedure. The expected performance of the accumulation in this low-photocount regime was compared with the data obtained from the system, and a reasonable level of agreement was demonstrated.

  11. Analysis of the performance of a coherent pulsed fiber lidar for aerosol backscatter applications (United States)

    Pearson, Guy N.; Roberts, P. John; Eacock, Justin R.; Harris, Michael


    The antenna and the Doppler estimation characteristics of a coherent pulsed lidar intended for short-range aerosol backscatter applications have been analyzed. The system used fiber-optic interconnects and operated at a wavelength of 1.548 mum. The range dependence of the signal for various bistatic and monostatic antenna configurations has been determined. The system operated in a low-pulse-energy, high-pulse-repetition-rate mode, and the Doppler estimates from the return signal were achieved with a multipulse accumulation procedure. The expected performance of the accumulation in this low-photocount regime was compared with the data obtained from the system, and a reasonable level of agreement was demonstrated.

  12. Dynamics of ponderomotive self-focusing and periodic bursts of stimulated Brillouin backscattering in plasmas

    International Nuclear Information System (INIS)

    Andreev, N.E.; Gorbunov, L.M.; Tarakanov, S.V.; Zykov, A.I.


    The space--time evolution of ponderomotive self-focusing of electromagnetic beams in a plasma is investigated. The quasineutral, hydrodynamic plasma response to the ponderomotive force is considered. The set of coupled quasioptic and acoustic equations is solved both analytically and numerically for slab and cylindrical beams. It is shown that the transient process of self-focusing has the form of a nonlinear wave propagating along the beam axis from boundary into the interior of a plasma with velocity considerably higher than the ion-sound velocity. Mutual dynamics of self-focusing and stimulated Brillouin backscattering (SBBS) is computed. It is shown that self-focusing results in the high intensity periodical bursts of SBBS. However, the time average level of scattered radiation is quite low

  13. Practical considerations in the calculation of orientation distribution functions from electron back-scattered diffraction patterns

    International Nuclear Information System (INIS)

    Bowen, A.W.


    Using model data sets for the Brass orientation, the importance of scatter width, angular accuracy and grain size and volume fraction on the sensitivity of the calculated Orientation Distribution Functions have been determined in order to highlight some of the practical considerations needed in the processing of experimental data from individual grain orientation measurements determined by the Electron Back-Scattered Diffraction technique. It is suggested that the most appropriate scatter width can be calculated from the maximum function height versus scatter width curve in order to accommodate variations in texture sharpness. The sensitivity of the ODF to careful sample preparation, mounting and pattern analysis, in order to keep errors in angular accuracy to 1 or less is demonstrated, as is the imperative need to correct for the size of grains, and their volume fractions. (orig.)

  14. Imaging near-surface heterogeneities by natural migration of backscattered surface waves

    KAUST Repository

    AlTheyab, Abdullah


    We present a migration method that does not require a velocity model to migrate backscattered surface waves to their projected locations on the surface. This migration method, denoted as natural migration, uses recorded Green\\'s functions along the surface instead of simulated Green\\'s functions. The key assumptions are that the scattering bodies are within the depth interrogated by the surface waves, and the Green\\'s functions are recorded with dense receiver sampling along the free surface. This natural migration takes into account all orders of multiples, mode conversions and non-linear effects of surface waves in the data. The natural imaging formulae are derived for both active source and ambient-noise data, and computer simulations show that natural migration can effectively image near-surface heterogeneities with typical ambient-noise sources and geophone distributions.

  15. Wuhan Ionospheric Oblique Backscattering Sounding System and Its Applications—A Review

    Directory of Open Access Journals (Sweden)

    Shuzhu Shi


    Full Text Available For decades, high-frequency (HF radar has played an important role in sensing the Earth’s environment. Advances in radar technology are providing opportunities to significantly improve the performance of HF radar, and to introduce more applications. This paper presents a low-power, small-size, and multifunctional HF radar developed by the Ionospheric Laboratory of Wuhan University, referred to as the Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS. Progress in the development of this radar is described in detail, including the basic principles of operation, the system configuration, the sounding waveforms, and the signal and data processing methods. Furthermore, its various remote sensing applications are briefly reviewed to show the good performance of this radar. Finally, some suggested solutions are given for further improvement of its performance.

  16. Research on application of CNN in Compton back-scattering image processing

    International Nuclear Information System (INIS)

    Wang Huaiying; Yang Lirui; Zhang Yujin


    A cellular neural network (CNN) is a large-scale nonlinear analog circuit suitable for real-time signal and image processing. CNN can be used for high-speed parallel computation and is easy to be translated into a VLSI implementation. This paper presents one new approach for Compton back-scattering (CBS) image filter and segmentation using CNN. Furthermore presents one new way for eliminating isolated point on CNN and morphologic method. CNN Some practical results are presented and briefly discussed, which demonstrates the successful operation of the proposed algorithm. Those new approaches is very affordable to parallelism and analog VLSI implementation, which allowing the CBS image processing to be performed in real-time. (authors)

  17. Image restoration techniques using Compton backscatter imaging for the detection of buried land mines (United States)

    Wehlburg, Joseph C.; Keshavmurthy, Shyam P.; Watanabe, Yoichi; Dugan, Edward T.; Jacobs, Alan M.


    Earlier landmine imaging systems used two collimated detectors to image objects. These systems had difficulty in distinguishing between surface features and buried features. Using a combination of collimated and uncollimated detectors in a Compton backscatter imaging (CBI) system, allows the identification of surface and buried features. Images created from the collimated detectors contain information about the surface and the buried features, while the uncollimated detectors respond (approximately 80%) to features on the surface. The analysis of surface features are performed first, then these features can be removed and the buried features can be identified. Separation of the surface and buried features permits the use of a globbing algorithm to define regions of interest that can then be quantified [area, Y dimension, X dimension, and center location (xo, yo)]. Mine composition analysis is also possible because of the properties of the four detector system. Distinguishing between a pothole and a mine, that was previously very difficult, can now be easily accomplished.

  18. Absorptive capacity and smart companies

    Directory of Open Access Journals (Sweden)

    Patricia Moro González


    Full Text Available Purpose: The current competitive environment is substantially modifying the organizations’ learning processes due to a global increase of available information allowing this to be transformed into knowledge. This opportunity has been exploited since the nineties by the tools of “Business Analytics” and “Business Intelligence” but, nevertheless, being integrated in the study of new organizational capacities engaged in the process of creating intelligence inside organizations is still an outstanding task. The review of the concept of absorptive capacity and a detailed study from the perspective of this new reality will be the main objective of study of this paper.Design/methodology/approach: By comparing classical absorptive capacity and absorptive capacity from the point of view of information management tools in each one of the three stages of the organizational learning cycle, some gaps of the former are overcome/fulfilled. The academic/bibliographical references provided in this paper have been obtained from ISI web of knowledge, Scopus and Dialnet data bases, supporting the state of affairs on absorptive capacity and thereafter filtering by "Business Intelligence" and "Business Analytics". Specialized websites and Business Schools` Publications there have also been included, crowning the content on information management tools used that are currently used in the strategic consulting.Findings: Our contribution to the literature is the development of "smart absorptive capacity". This is a new capacity emerging from the reformulation of the classical concept of absorptive capacity wherein some aspects of its definition that might have been omitted are emphasized. The result of this new approach is the creation of a new Theoretical Model of Organizational Intelligence, which aims to explain, within the framework of the Resources and Capabilities Theory, the competitive advantage achieved by the so-called smart companies

  19. Light Absorption By Coated Soot (United States)

    Sedlacek, A. J.; Lee, J.; Onasch, T. B.; Davidovits, P.; Cross, E. S.


    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds will increase black carbon (BC) radiative forcing from the IPCC best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of the uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. With the advent of techniques that can directly measure aerosol light absorption without influences due to collection substrate or light scattering (e.g., photoacoustic spectroscopy (Arnott et al., 2005; Lack et al., 2006) and photothermal interferometry (Sedlacek and Lee 2007)) the potential exists for quantifying this interdependence. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve this objective measurements of both the optical and physical properties of flame-generated soot under nascent, coated and denuded conditions were conducted. In this paper, light absorption by dioctyl sebacate (DOS) encapsulated soot and sulfuric acid coated soot using the technique of photothermal interferometry will be presented. In the case of DOS-coated soot, a monotonic increase in light absorption as a function DOS coating thickness to nearly 100% is observed. This observation is consistent with a coating-induced amplification in particle light absorption. (Bond et al. 2006) However

  20. Acoustic backscattering and radiation force on a rigid elliptical cylinder in plane progressive waves. (United States)

    Mitri, F G


    This work proposes a formal analytical theory using the partial-wave series expansion (PWSE) method in cylindrical coordinates, to calculate the acoustic backscattering form function as well as the radiation force-per-length on an infinitely long elliptical (non-circular) cylinder in plane progressive waves. The major (or minor) semi-axis of the ellipse coincides with the direction of the incident waves. The scattering coefficients for the rigid elliptical cylinder are determined by imposing the Neumann boundary condition for an immovable surface and solving a resulting system of linear equations by matrix inversion. The present method, which utilizes standard cylindrical (Bessel and Hankel) wave functions, presents an advantage over the solution for the scattering that is ordinarily expressed in a basis of elliptical Mathieu functions (which are generally non-orthogonal). Furthermore, an integral equation showing the direct connection of the radiation force function with the square of the scattering form function in the far-field from the scatterer (applicable for plane waves only), is noted and discussed. An important application of this integral equation is the adequate evaluation of the radiation force function from a bistatic measurement (i.e., in the polar plane) of the far-field scattering from any 2D object of arbitrary shape. Numerical predictions are evaluated for the acoustic backscattering form function and the radiation force function, which is the radiation force per unit length, per characteristic energy density, and per unit cross-sectional surface of the ellipse, with particular emphasis on the aspect ratio a/b, where a and b are the semi-axes, as well as the dimensionless size parameter kb, without the restriction to a particular range of frequencies. The results are particularly relevant in acoustic levitation, acousto-fluidics and particle dynamics applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Liquid crystal-based biosensor with backscattering interferometry: A quantitative approach. (United States)

    Khan, Mashooq; Park, Soo-Young


    We developed a new technology that uses backscattering interferometry (BSI) to quantitatively measure nematic liquid crystal (NLC)-based biosensors, those usually relied on texture reading for on/off signals. The LC-based BSI comprised an octadecyltrichlorosilane (OTS)-coated square capillary filled with 4-cyano-4'-pentylbiphenyl (5CB, a nematic LC at room temperature). The LC/water interface in the capillary was functionalized by a coating of poly(acrylicacid-b-4-cyanobiphenyl-4'-oxyundecylacrylate) (PAA-b-LCP) and immobilized with the enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP) through covalent linkage to the PAA chains (5CB PAA-GOx:HRP ) for glucose detection. Laser irradiation of the LC near the LC/water interface resulted in backscattered fringes with high contrast. The change in the spatial position of the fringes (because of the change in the orientation of the LC caused by the GOx:HRP enzymatic reaction of glucose) altered the output voltage of the photodetector when its active area was aligned with the edge of one of the fringes. The change in the intensity at the photodetector allowed the detection limit of the instrument to be as low as 0.008mM with a linear range of 0.02-9mM in a short response time (~60s). This LC-based BSI technique allows for quantitative, sensitive, selective, reproducible, easily obtainable, and interference-free detection in a large linear dynamic range and for practical applications with human serum. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Assessing strain mapping by electron backscatter diffraction and confocal Raman microscopy using wedge-indented Si

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, Lawrence H.; Vaudin, Mark D.; Stranick, Stephan J.; Stan, Gheorghe; Gerbig, Yvonne B.; Osborn, William; Cook, Robert F., E-mail:


    The accuracy of electron backscatter diffraction (EBSD) and confocal Raman microscopy (CRM) for small-scale strain mapping are assessed using the multi-axial strain field surrounding a wedge indentation in Si as a test vehicle. The strain field is modeled using finite element analysis (FEA) that is adapted to the near-indentation surface profile measured by atomic force microscopy (AFM). The assessment consists of (1) direct experimental comparisons of strain and deformation and (2) comparisons in which the modeled strain field is used as an intermediate step. Direct experimental methods (1) consist of comparisons of surface elevation and gradient measured by AFM and EBSD and of Raman shifts measured and predicted by CRM and EBSD, respectively. Comparisons that utilize the combined FEA–AFM model (2) consist of predictions of distortion, strain, and rotation for comparison with EBSD measurements and predictions of Raman shift for comparison with CRM measurements. For both EBSD and CRM, convolution of measurements in depth-varying strain fields is considered. The interconnected comparisons suggest that EBSD was able to provide an accurate assessment of the wedge indentation deformation field to within the precision of the measurements, approximately 2×10{sup −4} in strain. CRM was similarly precise, but was limited in accuracy to several times this value. - Highlights: • We map strain by electron backscatter diffraction and confocal Raman microscopy. • The test vehicle is the multi-axial strain field of wedge-indented silicon. • Strain accuracy is assessed by direct experimental intercomparison. • Accuracy is also assessed by atomic force microscopy and finite element analyses. • Electron diffraction measurements are accurate; Raman measurements need refinement.

  3. Finite element modeling of grain size effects on the ultrasonic microstructural noise backscattering in polycrystalline materials. (United States)

    Bai, X; Tie, B; Schmitt, J-H; Aubry, D


    The correlation between ultrasonic wave propagation and polycrystalline microstructures has significant implications in nondestructive evaluation. An original numerical approach using the finite element method to quantify in both time and frequency domains the ultrasonic noise scattering due to the elastic heterogeneity of polycrystalline microstructures is presented. Based on the reciprocity theorem, it allows the scattering evaluation using mechanical data recorded only on the boundary of polycrystal instead of within its volume and is applicable to any polycrystalline aggregate regardless of its crystallographic or morphological characteristics. Consequently it gives a more realistic and accurate access of polycrystalline microstructures than the classical analytical models developed under the assumption of single scattering and the Born approximation. The numerical approach is proposed within the same unified theoretical framework as the classical analytical models, so it is possible to validate it in the cases of idealized microstructures for which the considered analytical models remain relevant. As an original result, assuming single phase, untextured and equiaxed microstructures, two-dimensional (2D) theoretical formulas are developed and a frequency-dependent coefficient is found compared to the classical three-dimensional (3D) formulas. 2D numerical simulations are then performed for idealized microstructures composed of hexagonal grains with a uniform grain-size. Three grain sizes are considered herein and involve different scattering regions. Good comparisons are obtained between theoretical and numerical estimates of the backscattering coefficient, which validate the numerical approach. Effects of the grain boundary orientations are analyzed by modeling an irregular hexagonal grain morphology and a random grain morphology generated by an established Voronoi approach. The origin of the significant oscillation level of backscattering is then investigated

  4. AnyStitch: a tool for combining electron backscatter diffraction data sets. (United States)

    Pilchak, A L; Shiveley, A R; Tiley, J S; Ballard, D L


    Recent advances in electron backscatter diffraction equipment and software have permitted increased data acquisition rates on the order of hundreds of points per second with additional increases in the foreseeable future likely. This increase in speed allows users to collect data from statistically significant areas of samples by combining beam-control scans and automated stage movements. To facilitate data analysis, however, the individual tiles must be combined, or stitched, into a single data set. In this paper, we describe a matlab(®) (The Mathworks, Inc., Natick, MA, USA) program to facilitate stitching of electron backscatter diffraction data. The method offers users a wide range of controls for tile placement including independent overlaps for horizontal and vertical tiles and also includes a parameter to account for systematic stage positioning errors or improperly calibrated scan rotation. The code can stitch data collected on either square or hexagonal grids and contains a function to reduce the resolution of square grid data if the resulting file is too large (or has too many grains) to be opened by the analysis software. The software was primarily written to work with TSL(®) OIM™ data sets and includes a function to quickly read compressed *.osc files into a variable in the matlab(®) workspace as opposed to using slower, text-reading functions. The output file is in *.ang format and can be opened directly by TSL(®) OIM™ Analysis software. A set of functions to facilitate stitching of text-based *.ctf files produced by Oxford Instruments HKL systems are also included. Finally, the code can also be used to combine *.tif images to produce a montage. The source code, a graphical user interface and a compiled version of the software was made available in the online version of this paper. Published 2011. This article is a US Government work and is in the public domain in the USA.

  5. Quantitative assessments of burn degree by high-frequency ultrasonic backscattering and statistical model

    International Nuclear Information System (INIS)

    Lin, Yi-Hsun; Wang, Shyh-Hau; Huang, Chih-Chung


    An accurate and quantitative modality to assess the burn degree is crucial for determining further treatments to be properly applied to burn injury patients. Ultrasounds with frequencies higher than 20 MHz have been applied to dermatological diagnosis due to its high resolution and noninvasive capability. Yet, it is still lacking a substantial means to sensitively correlate the burn degree and ultrasonic measurements quantitatively. Thus, a 50 MHz ultrasound system was developed and implemented to measure ultrasonic signals backscattered from the burned skin tissues. Various burn degrees were achieved by placing a 100 deg. C brass plate onto the dorsal skins of anesthetized rats for various durations ranged from 5 to 20 s. The burn degrees were correlated with ultrasonic parameters, including integrated backscatter (IB) and Nakagami parameter (m) calculated from ultrasonic signals acquired from the burned tissues of a 5 x 1.4 mm (width x depth) area. Results demonstrated that both IB and m decreased exponentially with the increase of burn degree. Specifically, an IB of -79.0 ± 2.4 (mean ± standard deviation) dB for normal skin tissues tended to decrease to -94.0 ± 1.3 dB for those burned for 20 s, while the corresponding Nakagami parameters tended to decrease from 0.76 ± 0.08 to 0.45 ± 0.04. The variation of both IB and m was partially associated with the change of properties of collagen fibers from the burned tissues verified by samples of tissue histological sections. Particularly, the m parameter may be more sensitive to differentiate burned skin due to the fact that it has a greater rate of change with respect to different burn durations. These ultrasonic parameters in conjunction with high-frequency B-mode and Nakagami images could have the potential to assess the burn degree quantitatively.

  6. High-energy helium backscattering for the compositional analysis of thin-film oxide-superconductors

    International Nuclear Information System (INIS)

    Hubbard, K.M.; Martin, J.A.; Muenchausen, R.E.; Tesmer, J.R.; Nastasi, M.


    Recent experiments have demonstrated that the broad elastic-scattering resonance for 8.8 MeV helium bombardment of oxygen can be exploited to measure the oxygen content of YBaCuO thin films. A potential difficulty with such measurements is distortion of the backscattering spectrum due to resonant scattering from the substrate elements, which could prevent the accurate integration of peak areas. We have measured the elastic scattering cross sections for Sr and Ti, relative to Gd, with He ions in the energy range of 2.2--8.8 MeV, and a scattering angle of 166 degree. The results verify that resonant scattering from the substrate does not interfere with the high-energy compositional analysis of YBaCuO films deposited on SrTiO 3 . Scattering cross sections for Ca, measured relative to Ba, have also been determined for application to the analysis of BiSrCaCuO and TlCaBaCuO films. Because of resonant scattering from Ca at beam energies above 6 MeV, two backscattering measurements are required for these materials: one at 8.8 MeV to determine the O content, and one at or below 6 MeV to determine the Ca content. Anticipating a more general applicability of this technique to the analysis of metal-oxide films, data are also presented for a number of elements, as an empirical guideline, which give the beam energies above which scattering cross sections deviate from their Rutherford values, and must be determined experimentally. 10 refs., 6 figs., 4 tabs

  7. SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hurwitz, M; Margalit, D; Williams, C [Brigham and Women’s Hospital / Harvard Medical School, Boston, MA (United States); Tso, T; Lee, S; Rosen, E [Harvard School of Dental Medicine, Boston, MA (United States)


    Purpose: High-density materials used in dental restoration can cause significant localized dose enhancement due to electron backscatter in head-and-neck radiotherapy, increasing the risk of mucositis. The materials used in prosthetic dentistry have evolved in the last decades from metal alloys to ceramics. We aim to determine the dose enhancement caused by backscatter from currently-used dental materials. Methods: Measurements were performed for three different dental materials: lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), zirconium dioxide (ZrO{sub 2}), and gold alloy. Small thin squares (2×2×0.15 cm{sup 3}) of the material were fabricated, and placed into a phantom composed of tissue-equivalent material. The phantom was irradiated with a single 6 MV photon field. A thin-window parallel-plate ion chamber was used to measure the dose at varying distances from the proximal interface between the material and the plastic. Results: The dose enhancement at the interface between the high-density and tissue-equivalent materials, relative to a homogeneous phantom, was 54% for the gold alloy, 31% for ZrO{sub 2}, and 9% for Li{sub 2}Si{sub 2}O{sub 5}. This enhancement decreased rapidly with distance from the interface, falling to 11%, 5%, and 0.5%, respectively, 2 mm from the interface. Comparisons with the modeling of this effect in treatment planning systems are performed. Conclusion: While dose enhancement due to dental restoration is smaller with ceramic materials than with metal alloys, it can still be significant. A spacer of about 2–3 mm would be effective in reducing this enhancement, even for metal alloys.

  8. Relation between weather radar equation and first-order backscattering theory

    Directory of Open Access Journals (Sweden)

    F. S. Marzano


    Full Text Available Aim of this work is to provide a new insight into the physical basis of the meteorological-radar theory in attenuating media. Starting form the general integral form of the weather radar equation, a modified form of the classical weather radar equation at attenuating wavelength is derived. This modified radar equation includes a new parameter, called the range-bin extinction factor, taking into account the rainfall path attenuation within each range bin. It is shown that, only in the case of low-to-moderate attenuating media, the classical radar equation at attenuating wavelength can be used. These theoretical results are corroborated by using the radiative transfer theory where multiple scattering phenomena can be quantified. From a new definition of the radar reflectivity, in terms of backscattered specific intensity, a generalised radar equation is deduced. Within the assumption of first-order backscattering, the generalised radar equation is reduced to the modified radar equation, previously obtained. This analysis supports the conclusion that the description of radar observations at attenuating wavelength should include, in principle, first-order scattering effects. Numerical simulations are performed by using statistical relationships among the radar reflectivity, rain rate and specific attenuation, derived from literature. Results confirm that the effect of the range-bin extinction factor, depending on the considered frequency and range resolution, can be significant at X band for intense rain, while at Ka band and above it can become appreciable even for moderate rain. A discussion on the impact of these theoretical and numerical results is finally included.

  9. Morphology and possible origins of near-range oblique HF backscatter at high and midlatitudes (United States)

    Ponomarenko, Pavlo, V.; Iserhienrhien, Blessing; St.-Maurice, Jean-Pierre


    High-frequency radars (HF, ˜10-20 MHz) forming the Super Dual Auroral Radar Network (SuperDARN) regularly observe returns from very close ranges of ≤300-400 km (near-range echoes, NREs). These echoes are conventionally attributed to backscatter from meteor trails, but other sources of NRE have been invoked, including polar mesospheric summer echoes (PMSE), and non-field-aligned E region irregularities leading to high-aspect ionospheric returns. In order to relate NRE to a particular mechanism, it is essential to establish beforehand their spatiotemporal trends with respect to season, local time, and latitude. Systematic information of this kind is generally lacking from the literature, so we attempt to fill the gap by performing a statistical analysis of such echoes observed by five radars covering midlatitudes to polar latitudes over all seasons and local times. We detected two major echo populations which were observed at each radar site: (i) a nightside-early morning returns representing the well-known meteor backscatter and (ii) a midsummer population centered near the local noon. At high latitudes the summer daytime echoes are usually interpreted as PMSE, but the observed population extends to much lower latitudes and is centered well above the conventional PMSE height range. We hypothesize that this population could be related to neutral turbulence in the lower E region. In addition, there was a pronounced evening population restricted to the auroral region which we provisionally attribute to irregularities generated by the precipitating energetic particles and strong electric fields.

  10. Mask CD relationship to temperature at the time backscatter is received (United States)

    Zable, Harold; Kronmiller, Tom; Pearman, Ryan; Guthrie, Bill; Shirali, Nagesh; Masuda, Yukihiro; Kamikubo, Takashi; Nakayamada, Noriaki; Fujimura, Aki


    Mask writers need to be able to write sub-50nm features accurately. Nano-imprint lithography (NIL) masters need to create sub-20nm line and space (L:S) patterns reliably. Increasingly slower resists are deployed, but mask write times need to remain reasonable. The leading edge EBM-9500 offers 1200A/cm2 current density to shoot variable shaped beam (VSB) to write the masks. Last year, thermal effect correction (TEC) was introduced by NuFlare in the EBM-95001. It is a GPU-accelerated inline correction for the effect that the temperature of the resist has on CD. For example, a 100nm CD may print at 102nm where that area was at a comparably high temperature at the time of the shot. Since thermal effect is a temporal effect, the simulated temperature of the surface of the mask is dynamically updated for the effect of each shot in order to accurately predict the cumulative effect that is the temperature at the location of the shot at the time of the shot and therefore its impact on CD. The shot dose is changed to reverse the effects of the temperature change. This paper for the first time reveals an enhancement to this thermal model and a simulator for it. It turns out that the temperature at the time each location receives backscatter from other shots also make a difference to the CD. The effect is secondary, but still measurable for some resists and substrates. Results of a test-chip study will be presented. The computation required for the backscatter effect is substantial. It has been demonstrated that this calculation can be performed fast enough to be inline with the EBM-9500 with a reasonable-sized computing platform. Run-time results and the computing architecture will be presented.

  11. In situ quantitative characterisation of the ocean water column using acoustic multibeam backscatter data (United States)

    Lamarche, G.; Le Gonidec, Y.; Lucieer, V.; Lurton, X.; Greinert, J.; Dupré, S.; Nau, A.; Heffron, E.; Roche, M.; Ladroit, Y.; Urban, P.


    Detecting liquid, solid or gaseous features in the ocean is generating considerable interest in the geoscience community, because of their potentially high economic values (oil & gas, mining), their significance for environmental management (oil/gas leakage, biodiversity mapping, greenhouse gas monitoring) as well as their potential cultural and traditional values (food, freshwater). Enhancing people's capability to quantify and manage the natural capital present in the ocean water goes hand in hand with the development of marine acoustic technology, as marine echosounders provide the most reliable and technologically advanced means to develop quantitative studies of water column backscatter data. This is not developed to its full capability because (i) of the complexity of the physics involved in relation to the constantly changing marine environment, and (ii) the rapid technological evolution of high resolution multibeam echosounder (MBES) water-column imaging systems. The Water Column Imaging Working Group is working on a series of multibeam echosounder (MBES) water column datasets acquired in a variety of environments, using a range of frequencies, and imaging a number of water-column features such as gas seeps, oil leaks, suspended particulate matter, vegetation and freshwater springs. Access to data from different acoustic frequencies and ocean dynamics enables us to discuss and test multifrequency approaches which is the most promising means to develop a quantitative analysis of the physical properties of acoustic scatterers, providing rigorous cross calibration of the acoustic devices. In addition, high redundancy of multibeam data, such as is available for some datasets, will allow us to develop data processing techniques, leading to quantitative estimates of water column gas seeps. Each of the datasets has supporting ground-truthing data (underwater videos and photos, physical oceanography measurements) which provide information on the origin and

  12. Study of the thermal diffusion of ion-alloyed cesium in aluminium, silicon and titanium by the Rutherford backscattering method

    International Nuclear Information System (INIS)

    Bulgakov, Yu.V.; Savel'eva, L.M.


    Thermal diffusion of cesium implanted at 120 keV energy in monocrystal silicon and in polycrystal aluminium and titanium is investigated by the method of Rutherford backscattering (RBS). Parameters of temperature dependence of the cesium diffusion coefficient in materials given above are determined. Cesium is shown to be one of the most movable impurities

  13. L-Band SAR Backscatter Related to Forest Cover, Height and Aboveground Biomass at Multiple Spatial Scales across Denmark

    DEFF Research Database (Denmark)

    Joshi, Neha P.; Mitchard, Edward T A; Schumacher, Johannes


    may be confounded by variations in biophysical forest structure (density, height or cover fraction) and differences in the resolution of satellite and ground data. Here, we attempt to quantify the effect of these factors by relating L-band ALOS PALSAR HV backscatter and unique country-wide Li...

  14. Three-dimensional cathodoluminescence imaging and electron backscatter diffraction: tools for studying the genetic nature of diamond inclusions

    NARCIS (Netherlands)

    Wiggers de Vries, D.F.; Drury, M.R.; Winter, D.A.M.; Bulanova, G.P.; Pearson, D.G.; Davies, G.R.


    As a step towards resolving the genesis of inclusions in diamonds, a new technique is presented. This technique combines cathodoluminescence (CL) and electron backscatter diffraction (EBSD) using a focused ion beam-scanning electron microscope (FIB-SEM) instrument with the aim of determining, in

  15. Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.


    This study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria‐stabilized zirconia (YSZ) and Nb‐doped strontium titanate (STN) to optimize data quality and acquisition time for 3D‐EBSD experiments by FIB...

  16. Extracting integrated and differential cross sections in low-energy heavy-ion reactions from backscattering measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sargsyan, V.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Yerevan State University, Yerevan (Armenia); Adamian, G.G.; Antonenko, N.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Diaz-Torres, A. [European Centre for Theoretical Studies in Nuclear Physics and Related Areas, Villazzano (Italy); Gomes, P.R.S. [Universidade Federal Fluminense, Instituto de Fisica, Niteroi (Brazil); Lenske, H. [Institut fuer Theoretische Physik der Justus-Liebig-Universitaet, Giessen (Germany)


    We suggest new methods to extract elastic (quasi-elastic) scattering angular distribution and reaction (capture) cross sections from the experimental elastic (quasi-elastic) backscattering excitation function taken at a single angle. A novel Coulomb scattering relation between angular momentum and centrifugal energy is used. The methodology is developed for addressing complementary reaction observables, improving the description of elastic differential cross section. (orig.)

  17. A study of a dual polarization laser backscatter system for remote identification and measurement of water pollution (United States)

    Sheives, T. C.


    Remote identification and measurement of subsurface water turbidity and oil on water was accomplished with analytical models which describe the backscatter from smooth surface turbid water, including single scatter and multiple scatter effects. Lidar measurements from natural waterways are also presented and compared with ground observations of several physical water quality parameters.


    Directory of Open Access Journals (Sweden)

    L. Yang


    Full Text Available Due to the forward scattering and block of radar signal, the water, bare soil, shadow, named low backscattering objects (LBOs, often present low backscattering intensity in polarimetric synthetic aperture radar (PolSAR image. Because the LBOs rise similar backscattering intensity and polarimetric responses, the spectral-based classifiers are inefficient to deal with LBO classification, such as Wishart method. Although some polarimetric features had been exploited to relieve the confusion phenomenon, the backscattering features are still found unstable when the system noise floor varies in the range direction. This paper will introduce a simple but effective scene classification method based on Bag of Words (BoW model using Support Vector Machine (SVM to discriminate the LBOs, without relying on any polarimetric features. In the proposed approach, square windows are firstly opened around the LBOs adaptively to determine the scene images, and then the Scale-Invariant Feature Transform (SIFT points are detected in training and test scenes. The several SIFT features detected are clustered using K-means to obtain certain cluster centers as the visual word lists and scene images are represented using word frequency. At last, the SVM is selected for training and predicting new scenes as some kind of LBOs. The proposed method is executed over two AIRSAR data sets at C band and L band, including water, bare soil and shadow scenes. The experimental results illustrate the effectiveness of the scene method in distinguishing LBOs.

  19. A proposal on evaluation method of neutron absorption performance to substitute conventional neutron attenuation test

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Je Hyun; Shim, Chang Ho [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of); Kim, Sung Hyun [Nuclear Fuel Cycle Waste Treatment Research Division, Research Reactor Institute, Kyoto University, Osaka (Japan); Choe, Jung Hun; Cho, In Hak; Park, Hwan Seo [Ionizing Radiation Center, Nuclear Fuel Cycle Waste Treatment Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Hyun Seo; Kim, Jung Ho; Kim, Yoon Ho [Ionizing Radiation Center, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)


    For a verification of newly-developed neutron absorbers, one of guidelines on the qualification and acceptance of neutron absorbers is the neutron attenuation test. However, this approach can cause a problem for the qualifications that it cannot distinguish how the neutron attenuates from materials. In this study, an estimation method of neutron absorption performances for materials is proposed to detect both direct penetration and back-scattering neutrons. For the verification of the proposed method, MCNP simulations with the experimental system designed in this study were pursued using the polyethylene, iron, normal glass and the vitrified form. The results show that it can easily test neutron absorption ability using single absorber model. Also, from simulation results of single absorber and double absorbers model, it is verified that the proposed method can evaluate not only the direct thermal neutrons passing through materials, but also the scattered neutrons reflected to the materials. Therefore, the neutron absorption performances can be accurately estimated using the proposed method comparing with the conventional neutron attenuation test. It is expected that the proposed method can contribute to increase the reliability of the performance of neutron absorbers.

  20. A proposal on evaluation method of neutron absorption performance to substitute conventional neutron attenuation test

    International Nuclear Information System (INIS)

    Kim, Je Hyun; Shim, Chang Ho; Kim, Sung Hyun; Choe, Jung Hun; Cho, In Hak; Park, Hwan Seo; Park, Hyun Seo; Kim, Jung Ho; Kim, Yoon Ho


    For a verification of newly-developed neutron absorbers, one of guidelines on the qualification and acceptance of neutron absorbers is the neutron attenuation test. However, this approach can cause a problem for the qualifications that it cannot distinguish how the neutron attenuates from materials. In this study, an estimation method of neutron absorption performances for materials is proposed to detect both direct penetration and back-scattering neutrons. For the verification of the proposed method, MCNP simulations with the experimental system designed in this study were pursued using the polyethylene, iron, normal glass and the vitrified form. The results show that it can easily test neutron absorption ability using single absorber model. Also, from simulation results of single absorber and double absorbers model, it is verified that the proposed method can evaluate not only the direct thermal neutrons passing through materials, but also the scattered neutrons reflected to the materials. Therefore, the neutron absorption performances can be accurately estimated using the proposed method comparing with the conventional neutron attenuation test. It is expected that the proposed method can contribute to increase the reliability of the performance of neutron absorbers