Application of dispersion sum rules to non-forward high-energy scattering
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Soloviev, L. D.↗
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Flow cytometry of human embryonic kidney cells: A light scattering approach
The mammalian kidney contains cells that transport water, convert vitamin D to active forms, synthesize hormones such a renin and erythropoietin, and produce enzymes such as urokinase, a plasminogen activator. Several of these functions are maintained by human embryonic kidney cells (HEK) cultivated in vitro. Biochemical study of these functions in their individual cell types in vitro requires purified populations of cells. Light-scattering activated cell sorting (LACS) was explored as a means of achieving such purifications. It was found that HEK cells at the first 1 to 5 passages in culture were heterogeneous with respect to 2-parameter light scattering intensity distribution, in which combined measurements included forward angle scattering (2.5 to 19 deg), 90 deg scattering, and time-of-flight size measurements. Size was measured at a resolution of 0.15 microns/channel in 256 channels using pulse-height independent pulse-width measurements. Two-parameter distributions combining these measurements were obtained for HEK cell subpopulations that had been purified by microgravity electrophoresis and subsequently propagated in culture. These distributions contained at least 3 subpopulations in all purified fractions, and results of experiments with prepurified cultured HEK cells indicated that subpopulations of living cells that were high in plasminogen-activator activity also contained the highest per cent of cells with high 90 deg light scatter intensity.
Kunze, M. E.↗
An optical model for composite nuclear scattering
The optical model of composite particle scattering is considered and compared to the accuracies of other models. A nonrelativistic Schroedinger equation with two-body potentials is used for the scattering of a single particle by an energy-dependent local potential. The potential for the elastic channel is composed of matrix elements of a single scattering operator taken between the ground states of the projectile and the target; the coherent amplitude is considered as dominating the scattering in the forward direction. A multiple scattering series is analytically explored and formally summed by the solution of an equivalent Schroedinger equation. Cross sections of nuclear scattering are then determined for He-4 and C-12 nuclei at 3.6 GeV/nucleus and O-16 projectiles at 2.1 GeV/nucleus, and the optical model approximations are found to be consistently lower and more accurate than approximations made by use of Glauber's theory.
Wilson, J. W.↗
Observations of nonlinear scattering from a plasma column.
Nonlinear interaction effects are considered for signals incident on an unmagnetized cold plasma column, without making the quasi-static approximation. It is found that the nonlinearly generated quadrupole component is only modified slightly and that no multipolar component can give a forward- or back-scattered signal. However, strong nonlinear forward scattering was observed in previous experiments. This spurious result has been traced to the effect of the earth's magnetic field. When this is cancelled, predominantly quadrupolar radiation is observed, in agreement with theory.
Bruce, R. L.↗
Community Radiative Transfer Model: Implementing A New Cloud Scattering Database and Developing the Forward Radar Module
The Mie theory is used by many fast RT models to estimate the optical properties of single particles. The Mie theory assumes spherical shapes for ice or snow particles with mixture of air and ice. However, hydrometeors scattering radiation at microwave frequencies have different shapes, sizes, and orientations. Therefore, using Mie theory to determine their optical properties leads to large uncertainties in all-sky radiative transfer calculations. The discrete dipole approximation (DDA) which approximates the optical properties of large objects in terms of discrete dipoles has shown promises in calculating the scattering properties of particles with different shapes in the microwave frequencies. The goal of the research was to enhance the CRTM scattering calculations for frozen hydrometeors in the microwave frequencies using the DDA technique. Given that such optical properties cannot be practically calculated on the fly, pre-computed look-up tables need to be implemented into the fast RT models to calculate the scattering properties of these particles using the DDA technique and the inputs provided by the users. Therefore, we implemented such pre-computed DDA databases into CRTM. In addition to using stand-alone CRTM calculations using collocated ATMS and reanalysis profiles, the data assimilation experiments conducted using the NOAA FV3GFS forecast system will be used to evaluate the scattering improvements. Additionally, we used the backscattering information from the DDA database to implement a radar simulator into CRTM. The radar operators takes advantage of CRTM different modules to calculate clouds absorption and scattering properties. In addition to the forward model both adjoint and tangent linear of the radar simulator are implemented and evaluated as well. The radar simulator is currently being tested within the JEDI/GEOS data assimilation framework to facilitate the assimilation of radar measurements such as CloudSat CPR and GPM DPR into the NASA GEOS model.
Isaac Moradi↗
Microwave scattering by a plasma covered sphere
Forward angle microwave scattering by plasma covered magnetized metallic sphere, calculating radial electron density distribution
Quinn, R. G.↗
Photometric studies of light scattering above the lunar terminator from Apollo solar corona photography
Excess brightness is found in 70-mm photographs of the solar corona above the lunar terminator during Apollo 15 and 17. Maximum brightness of this scattered light is determined from calibration of image density. The observed excess brightness displays circular symmetry above the lunar-horizon subsolar point, characteristic of forward diffraction scattering from micron or submicron size (solid) grains, and decays rapidly in intensity with altitude and distance from the lunar terminator. The observed brightness cannot be accounted for by a co-orbiting cloud of spacecraft contaminants, but requires a variable lunar dust 'atmosphere' over the terminator regions extending to altitudes in excess of 100 km. To maintain such large masses of lunar fines above the terminator requires either local mass-churning rates in excess of 2 by 10 to the -11th power g/sq cm sec or the assumption of some degree of high-altitude electrostatic suspension to increase the dwell time of individual grains at the altitudes observed. Such a model would reduce mass-churning rates while causing selective erosion/deposition and potential for escape of significant mass from the moon
Mccoy, J. E.↗
Wideband Interferometric Sensing and Imaging Polarimetry
Wideband Interferometric Sensing and Imaging Polarimetry (WISIP) has become an important, indispensible tool in wide area military surveillance and global environmental monitoring of the terrestrial and planetary covers. It enables dynamic, real time optimal feature extraction of significant characteristics of desirable targets and/or target sections with simultaneous suppression of undesirable background clutter and propagation path speckle at hitherto unknown clarity and never before achieved quality. WISIP may be adopted to the detection, recognition, and identification (DRI) of any stationary, moving or vibrating targets or distributed scatterer segments versus arbitrary stationary, dynamical changing and/or moving geo-physical/ecological environments, provided the instantaneous 2x2 phasor and 4x4 power density matrices for forward propagation/backward scattering, respectively, can be measured with sufficient accuracy. For example, the DRI of stealthy, dynamically moving inhomogeneous volumetric scatter environments such as precipitation scatter, the ocean/sea/lake surface boundary layers, the littoral coastal surf zones, pack ice and snow or vegetative canopies, dry sands and soils, etc. can now be successfully realized. A comprehensive overview is presented on how these modern high resolution/precision, complete polarimetric co-registered signature sensing and imaging techniques, complemented by full integration of novel navigational electronic tools, such as DGPS, will advance electromagnetic vector wave sensing and imaging towards the limits of physical realization. Various examples utilizing the most recent image data take sets of airborne, space shuttle, and satellite imaging systems demonstrate the utility of WISIP.
Verdi, James Salvatore↗
Kaon-nucleus scattering
The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.
Hong, Byungsik↗
Kaon-nucleus scattering
Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.
Hong, Byungsik↗
Scattering and Absorption by Nonspherical Particles in Planetary Atmospheres
The atmospheres of Mars, the giant planets, and Titan all support populations of nonspherical particles. Analyses of observations of these atmospheres therefore rely on an understanding of the optical properties of nonspherical particles. We can glean information on particle size and composition from the wavelength dependence of the optical depth and from the shape of the forward peak of the scattering phase function. Additional information comes from polarization measurements which have been especially fruitful for Titan's haze. The Mars atmosphere contains mineral dust particles with effective radii near 1.6 micro meters, and water ice particles with radii between about 1 and 4 micro meters. The uppermost tropospheric hazes in Jupiter and Saturn are composed of ice crystals of ammonia, water and possibly traces of ammonium hydrosulfide, Methane ice and hydrogen sulfide ice are present in the atmospheres of Uranus and Neptune. Size estimation for these hazes in the giant planets is difficult, and even the expected spectral signatures are elusive, Titan's haze is both forward scattering and strongly polarized - a combination which points toward a fractal aggregate struc1.ure of 10 - 100 or more organic monomers whose radius is about 0.06 micro meters. Polar stratospheric hazes on Jupiter and Saturn also display this characteristic.
nonsperical particles↗
Electromagnetic Scattering Analysis of Large Size Asteroids/Comets for Reflection/Transmission Tomography (RTT)
A precise knowledge of the interior structure of asteroids, comets, and Near Earth Objects (NEO) is important to assess the consequences of their impacts with the Earth and develop efficient mitigation strategies. Knowledge of their interior structure also provides opportunities for extraction of raw materials for future space activities. Low frequency radio sounding is often proposed for investigating interior structures of asteroids and NEOs. For designing and optimizing radio sounding instrument it is advantageous to have an accurate and efficient numerical simulation model of radio reflection and transmission through large size bodies of asteroid shapes. In this presentation we will present electromagnetic (EM) scattering analysis of electrically large size asteroids using (1) a weak form formulation and (2) also a more accurate hybrid finite element method/method of moments (FEM/MOM) to help estimate their internal structures. Assuming the internal structure with known electrical properties of a sample asteroid, we first develop its forward EM scattering model. From the knowledge of EM scattering as a function of frequency and look angle we will then present the inverse scattering procedure to extract its interior structure image. Validity of the inverse scattering procedure will be presented through few simulation examples.
Deshpande, Manohar↗
Diel Variations in Optical Properties of Micromonas pusilla, a Prasinophyte
A laboratory experiment was conducted on cultures of Micromonas pusilla, a marine prasinophyte, to investigate how cell growth and division affect the optical properties over the light:dark cycle. Measurements were made of cell size and concentration, attenuation and absorption coefficients, flow cytometric light scattering (in forward and side directions), chlorophyll and carbon content. Refractive index was calculated using the anomalous diffraction approximation Cells were about 1.5 micrometers in diameter and exhibited phased division, with the major division burst occurring during the night. Typical diel variations were observed, with cells increasing in size and light scattering during the day as they photosynthesize and decreasing at night upon division. The cells were in ultradian growth, with more than one division per day, at a light level of 120 Mu-mol photons m/sq/sec. Since these cells are similar in size to small phytoplankton that are typically abundant in field samples, these results can be used in the interpretation of diel variations in light scattering in natural populations of phytoplankton.
DuRand, Michele D.↗
Radar detection of the tropopause and clear air turbulence.
Radar detection of tropopause and clear air turbulence
TROPOPAUSE↗
Development of an experiment for visible radiation measurements from a satellite
The inversion problem, I.E., determining the atmospheric turbidity from polarimetry of radiation emerging from the earth's atmosphere, is presented. A major theoretical advance was made by finding a successful approximation for the forward peak scattering of aerosols together with a simplified characterization of particle size distributions. An engineering model of a multibarreled photopolarimeter suitable for operation from a satellite was evaluated in laboratory and high altitude jet aircraft tests. Comparison of the data from flights over the Mexican desert with theoretical curves for a Rayleigh atmosphere with negligible turbidity is in agreement.
Sekera, Z.↗
In situ measurement of particulate number density and size distribution from an aircraft
Commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micrometers in diameter. A specially designed pressurization system was used with this counter so that the sample could be fed into the monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 micrometers and greater in diameter.
Briehl, D.↗
In situ measurements of particulate number density and size distribution from an aircraft
Two different commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micron in diameter. A specially designed pressurization system was used with this monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 microns and greater in diameter. Considerable variation in number density was encountered for both classes of particles at the test altitudes ranging from 5 to 12 km. Presence of clouds could be detected by the light scattering instrument because large numbers of particles would then be registered by the instrument, especially in the size range above 5.0 microns in diameter.
Briehl, D.↗
Frequency-scanning particle size spectrometer
A particle size spectrometer having a fixed field of view within the forward light scattering cone at an angle theta sub s between approximately 100 and 200 minutes of arc (preferably at 150 minutes), a spectral range extending approximately from 0.2 to 4.0 inverse micrometers, and a spectral resolution between about 0.1 and 0.2 inverse micrometers (preferably toward the lower end of this range of spectral resolution), is employed to determine the distribution of particle sizes, independently of the chemical composition of the particles, from measurements of incident light, at each frequency, sigma (=1/lambda), and scattered light, I(sigma).
Fymat, A. L.↗