Maximum Degree Of Polarization Research Articles

Dependence of the radiation just above and below the ocean surface on atmospheric and oceanic parameters

Radiance and degree of linear polarization of the upwelling and the downwelling radiation just above and below a ruffled ocean surface in a model atmosphere-ocean system are computed at the wavelengths of 0.5 and 0.75 microm with the doubling-adding method. Computational results show that: (1) maximum degree of polarization (P(max))a nd radiance in the corresponding direction (R(max)) f the upwelling radiation below the ocean surface are strongly dependent on the oceanic condition and that P(max) is affected by the atmospheric condition. The effect of surface wind is negligible. (2) P(max) and R(max) of the downwelling radiation just above the ocean surface are strongly dependent on the atmospheric condition, but are little affected by oceanic and surface conditions. A combined measurement of P(max) and R(max) is expected to provide useful information to infer atmospheric and oceanic conditions.

Hera variable-energy “mini” spin rotator and head-on ep collision scheme with choice of electron helicity

The novel scheme of spin rotation and head-on collision in the HERA electron-proton collider is described with emphasis on the means for obtaining a high degree of longitudinal electron polarization of either sign at the interaction points. The variable-energy “mini” rotator employed in this scheme is described and discussed, and also the depolarizing effect of radiative spin diffusion and the means to counteract it. The designed scheme covers the whole range of electron energies between 27 and 35 GeV, with a maximum degree of Sokolov-Ternov polarization of 84% at 35 GeV.

Predicted interplanetary distribution of Lyman-σ intensity and polarization

Our current understanding of the spatial and temporal distribution of interplan etary neutral hydrogen is currently limited to a comparison of Lyman-σ photometric data with predictions of the solar backscattered radiation using theoretical models. In this paper, how the uncertainties in current model calculations could be reduced through the future use of polarization measurements made from interplanetary spacecraft is investigated. In particular, inquiry into how a mapping of the degree of linear polarization made from a spacecraft at various locations in the Solar System can improve knowledge of the interstellar wind parameters, number density, temperature, and velocity, is made. A polarization measurement can, in principle, be made with very high precision. In this regard, being a relative quantity, a polarization measurement can be made independent of instrumental calibration and long-term sensitivity degredation. Furthermore, the sky distribution of both intensity and polarization has been calculated using a variety of models for the neutral hydrogen. It is found that the polarization distribution over the sky is quite different from that of the intensity distribution. It is also showed that the maximum degree of polarization of the Laymam-σ line increases with heliocentric distance of the spacecraft, varying from 0 up to ∼ 18% at 20 AU.

Some characteristics of the polarization properties of single-modeW-type waveguides

An experimental investigation was made of the natural birefringence and of the spectral dependence of the maximum degree of polarization of light traveling in three-layer single-mode W-type fiber waveguides. The linear and circular birefringence was determined. An analysis of the spectral dependence of the maximum degree of polarization revealed a coupling between the dominant and leaky modes in the investigated fiber waveguide. The results obtained were used to estimate the coupling coefficient.

On the size, shape, and orientation of noctilucent cloud particles

Conclusions about the size of noctilucent cloud particles are often made under the assumption that they are spherical. The small degree of circular polarization observed in the light from noctilucent clouds suggests, however, that the particles may be aligned, and hence nonspherical: unpolarized light is elliptically polarized upon single scattering by aligned particles. Yet no suitable mechanism-aerodynamic, electrical, magnetic-has been proposed which will align small (< 10 μm) mesospheric particles. A more likely explanation for the observed circular polarization is that the light illuminating noctilucent clouds has acquired ellipticity because of multiple scattering in the long atmospheric paths it traverses. Even if noctilucent cloud particles are nonspherical, however, presently accepted upper limits on their size (~0.1 μm) and volumetric scattering need not be revised: scattering by small ice spheres as well as ice ellipsoids of any shape is consistent with the observed angular dependence of the degree of linear polarization. Moreover, particles much larger than 0.1 μm, regardless of shape, will lower the maximum degree of linear polarization below that which has been observed. DOI: 10.1111/j.1600-0889.1983.tb00008.x

Comet West 1976 VI: Photopolarimetry by the Helios 2 Zodiacal Light Experiment

Shortly after it passed through perihelion on February 25, 1976 Comet West was observed by the Helios Zodiacal Light Experiment. Broadband photopolarimetric measurements of the head and of the tail were performed in three wavelength bands (U, B, V). The phase angles encountered range from 67° to 85°. The polarization measurements indicated wavelength independent linear polarization. The maximum degree of polarization in the visual channel was found to be .28 at a phase angle of 83°.

Electron impact polarization of X-ray lines from hydrogen-like ions during solar flares

The linear polarization of X-ray lines from highly charged hydrogenic ions is calculated under the assumption that the ions are collisionally excited by nonthermal electrons with an anisotropic pitch-angle distribution around magnetic field lines. The results are applied to the conditions in solar flares. The maximum degree of polarization to be expected is quite low, of the order of some percent. In case of favourable conditions it should be feasible to detect line polarization during flares if the short-wavelength fine-structure component of the Lα doublet is observed.

Effect of Specular Reflection at the Ground on Light Scattered from a Rayleigh Atmosphere

The method of Chandrasekhar is used to compute the parameters that characterize the scattered light leaving the top of a Rayleigh atmosphere. The atmosphere of this model lies above a smooth water surface, which reflects light according to Fresnel’s law. The combined atmosphere and water is called the Fresnel model. The results for the Fresnel model are compared with corresponding results for a second model, which is called the Lambert model, since its ground reflects light according to Lambert’s law. The reflectance at the ground is less than 0.1, if either the solar zenith angle θ0 0.6. The relative difference between the outward fluxes from the tops of the atmospheres of the two models is less than 0.07 if θ0 0.5, but the difference becomes large at small τ1. The maximum degree of polarization and the neutral-point positions at the top of the atmosphere of the Fresnel model are quite different from those of the Lambert model, when the total optical thickness is less than 0.5. The neutral points for the Fresnel model appear outside of the vertical plane through the sun for restricted ranges of both the total normal optical thickness and the solar zenith angle.

Polarized Brightness Distribution Over Cassiopeia a, the Crab Nebula, and Cygnus a at 1.55 CM Wavelength

view Abstract Citations (74) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarized Brightness Distribution Over Cassiopeia a, the Crab Nebula, and Cygnus a at 1.55 cm Wavelength Mayer, C. H. ; Hollinger, J. P. Abstract Observations with 1.7' resolution were made of Cassiopeia A, the Crab Nebula, and Cygnus A using the 140-foot reflector of the National Radio Astronomy Observatory and a polarimeter at 1.55-cm wave- length which measured directly the intensity with linear polarization oriented north-south and the Stokes parameters Q and U. These data were combined to determine the distribution of the total in- tensity of radiation, the intensity of linearly polarized radiation, and the degree and position angle of linear polarization for scans across the sources spaced at 0,8 intervals of declination. Cassiopeia A at 1.55-cm wavelength is a nearly circular source with enhanced regions of emission around the rim and remarkably symmetrical linear polarization of about 4.5 per cent around the rim and zero at the center of the source. The electric field is oriented circumferentially defining a radial mag- netic field associated with the polarized radiation. The total intensity contours of the Crab Nebula source are roughly elliptical and similar in shape and position to the outer envelope of the nebula, but the in- tensity of polarized radiation is concentrated in a smaller region centered about 0.5' south and 0.25' east of the center of the nebula with a maximum degree of polarization of about 16 per cent at position angle 154°. The distributions of total intensity and polarized intensity of Cygnus A are consistent with two point sources separated by 1.9' along position angle 109°. The total intensity of the east component is 12 per cent greater than that of the west component. The intensities of linearly polarized radiation from the two components are equal, but the polarization is nearly opposite Publication: The Astrophysical Journal Pub Date: January 1968 DOI: 10.1086/149418 Bibcode: 1968ApJ...151...53M full text sources ADS |

Polarized Brightness Distribution over Cassiopeia A, the Crab Neubla, and Cygnus A at 1.55-cm Wavelength.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarized Brightness Distribution over Cassiopeia A, the Crab Neubla, and Cygnus A at 1.55-cm Wavelength. Mayer, Cornell H. ; Hollinger, James P. Abstract Observations with 1; 7 resolution were made of Cassiopeia A, the Crab Xebula, and Cygnus A using the 140-ft reflector of the Xational Radio Astronomy Observatory and a polarimeter at 1.55-cm wavelength which measured directly the intensity with linear polarization oriented N-S, and the Stokes parameters Q and U on three separate scans. These data were combined to determine the distribution of total intensity, polarized intensity, and degree and position angle of linear polarization for scans across the sources spaced at o; 8 intervals of declination. Cassiopeia A at 1.55-cm wavelength is a nearly circular source with enhanced regions of emission around the rim, and remarkably symmetrical linear polarization of about 4.5% around the rim and zero at the center of the source. The electric field is oriented circumferentially defining a radial magnetic field associated with the polarized radiation. The total intensity contours of the Crab Xebula source are roughly ellpitical, but the intensity of polarized radiation is concentrated in a smaller region centered about 0,5 south and o; 25 east of the center of the nebula with a maximum degree of polarization of about 16% at position angle 1540. Both the total intensity and polarized intensity of Cygnus A are consistent with two point sources separated by 1;9 along position angle 1090. The total intensity of the east component is 12% greater than of the west component. The intensities of linearly polarized radiation from the two comQonents are equal, but the polarization is nearly `opposite; 8.6+1.3% at 41+40 for the east component, and 9.7+1.3% at 151+40 for the west component. Additional observations of lower accuracy and lower resolution of 2'.6 which were made with the 85-ft reflector of the Xaval Research Laboratory to measure the circularly polarized component of radiation gave negative results with values for circular polarization of less than 2+2% for all three sources. Publication: The Astronomical Journal Pub Date: September 1967 DOI: 10.1086/110553 Bibcode: 1967AJ.....72S.815M full text sources ADS |

Winkelverteilungen elastisch an Edelgas-Atomstrahlen gestreuter Elektronen; Spinpolarisation eines an Argon gestreuten 40 eV-Elektronenstrahls

The angular distribution of electrons scattered elastically by rare-gas atomic beams (He, Ne, Ar, Kr, Xe) has been investigated over the angular range from 20° to 155° and with electron energies between 5 eV and 1000 eV. The results are compared with theory. Only for energies above 300 eV the agreement is good. The angular dependence of polarization P(Θ) of electrons, elastically scattered by a beam of argon atoms, is measured in a double scattering experiment for an electron energy of 40 eV. Maximum degree of polarization measured isP=12.5% ± 2.5%.

A Study of the Polarization of Skylight

Results of polarization observations of cloudless daylight skies over Salisbury South Australia, are presented. The measurements were made in a narrow wavelength range centred at 5450 A. When clear atmospheric conditions prevailed, the maximum degree of polarization was approximately O� 65, but this was observed to fall to 0�45 on an xceptionally hazy day.

�ber die Abh�ngigkeit des Polarisationsgrades vom Streuwinkel bei Mott-Streuung langsamer Elektronen

The angular dependence of polarizationP(Θ) of electrons elastically scattered by a beam of mercury atoms is measured in a double scattering experiment for electron energies of 0,9; 1,2; and 1,5 keV. The results are compared with theory and found to be in good agreement. Maximum degree of polarization measured isP=0,53±0,10 (electron current 10−12A).

Polarization of bursts of solar radio emission at microwave frequencies

The intensity and polarization of solar radio bursts at 9400, 3750, 2000, and 1000 Mc/s have been continuously observed since 1957 July. At 3750 Mc/s, the linearly polarized components were also measured during 4 months from 1957 October till 1958 January [1]. The analysis of observations to 1958 May reveals the following points:1. Many bursts at these frequencies show a difference in the intensity of two circularly polarized components. Frequency distributions of maximum degree of polarization of bursts are shown in Fig. 1, where weak bursts are excluded to reduce errors. At 3750, 2000, and 1000 Mc/s, particularly at 3750 Mc/s, the bursts of small degree of polarization are predominant. Circularly polarized bursts are occasionally observed at 2000 and 1000 Mc/s, but at higher frequencies the degree of polarization is usually less than 50 per cent.2. At 3750 Mc/s, no linearly polarized components could be detected in 117 bursts for a bandwidth of 10 Mc/s. The burst at this frequency is usually composed of a small degree of circularly polarized component and a randomly polarized one.3. Sometimes the sense of polarization varies with frequency. An example is shown in Fig. 2. On this occasion, the degree of polarization is small at 3750 Mc/s and the sense of polarization reverses between 2000 and 3750 Mc/s. Roughly grouped in Table I are 129 bursts simultaneously observed at four frequencies. The reversal of sense was found in 64 per cent of such bursts. Sometimes the sense of polarization varies with time, as may be found in our monthly report. Some of such phenomena may be interpreted by the motion of the source from the preceding part of a bipolar spot group to the following one or vice versa [4].4. In Fig. 3, the bursts associated with flares are classified in three types as regards the sense of polarization, and they are allocated to each of four quadrants on the solar disk according to the position of the flares. At higher frequencies, the sense of polarization seems to correlate with the position of the source as in the case of S component [2, 3]. A precise distribution map at 9400 Mc/s is shown in Fig. 4.