Multiply scattered component of lidar returns

2002 ◽  
Vol 75 (4-5) ◽  
pp. 563-570
Author(s):  
V.V. Belov ◽  
A.B. Serebrennikov
Keyword(s):  
Scattered Component

scholarly journals Multitude of iron lines including a Compton-scattered component in OAO 1657 – 415 detected withChandra

2019 ◽  
Vol 483 (4) ◽  
pp. 5687-5693
Author(s):  
Pragati Pradhan ◽  
Gayathri Raman ◽  
Biswajit Paul
Keyword(s):  
Scattered Component

scholarly journals Cosmic Ray Evidence for the Magnetic Configuration of the Heliosphere

1981 ◽  
Vol 94 ◽  
pp. 397-398
Author(s):  
H. S. Ahluwalia
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Ground Level ◽  
The Sun ◽  
Ground Level Enhancement ◽  
Solar Cosmic Rays ◽  
Pile Up ◽  
Scattered Component

Sekido and Murakami (1958) proposed the existence of the heliosphere to explain the scattered component of the solar cosmic rays. The heliosphere of their conception is a spherical shell around the sun. The shell contains a highly-irregular magnetic field and serves to scatter the cosmic rays emitted by the sun. It thereby gives rise to an isotropic component of solar cosmic rays, following the maximum in the ground level enhancement (GLE). Meyer et al. (1956) showed that a similar picture applies to the GLE of 23 February 1956. They conclude that the inner and outer radii of the shell should be 1.4 AU and 5 AU respectively. They suggest that a shell is formed by the “pile-up” of the solar wind under pressure exerted by the interstellar magnetic field, as suggested by Davis (1955).

The influence of reflection coefficient statistics on the seismic method: scattering attenuation and transmission wavelets

1992 ◽  
Vol 439 (1905) ◽  
pp. 1-23 ◽  
Keyword(s):  
Reflection Coefficient ◽  
Seismic Energy ◽  
Reflection Coefficients ◽  
Mean Square ◽  
Statistical Parameters ◽  
Seismic Surveys ◽  
Reflection Seismic ◽  
Starting Point ◽  
Sonic Logs ◽  
Scattered Component

The propagation through layered media of seismic energy from reflection seismic surveys is discussed in terms of one dimensional elastic scattering. The effect of a layered overburden on the detectability of the underlying target horizons is investigated. The required signal from the target reflectors arises from the two-way forward-scattered component whereas the internal multiple noise (which tends to obscure the target reflections) arises from the back-scattered component. The starting point of the investigation is the O’Doherty-Anstey relation for the two-way transmission response. In this paper, using statistical models of real reflection series, we derive Q -like attenuation laws for the two-way transmission. Most real sequences of reflection coefficients have spectra which rise with frequency in the seismic band and this leads to signal attenuation which only approximates to that of a 'constant Q ’ type over small bands of frequency. The implications of the theory are checked for two very different types of overburden, one being a repetitive type of sedimentary sequence with a large mean square reflection coefficient and the other a non-repetitive sequence with a small mean square reflection coefficient, against synthetic seismograms derived from real sonic logs. The minimum phase wavelet predicted by the theory is shown to model adequately the first pulse of the two-way transmission waveform, carrying the greater part of the energy, and the lag of the first peak is given approximately in terms of the statistical parameters of the reflection coefficients in the overburden.

scholarly journals ASCA Observations of the Type-2 Quasar RXJ13434+0001 at z = 2.35

1999 ◽  
Vol 186 ◽  
pp. 365-365
Author(s):  
T. Yamada ◽  
Y. Ueda ◽  
T. Takahashi ◽  
K. Ohta ◽  
M. Cappi ◽  
...  
Keyword(s):  
Emission Line ◽  
High Redshift ◽  
X Ray ◽  
Scattered Component

RXJ 13434+0001 is a rare example of radio-quiet type-2 quasars at high redshift. It was discovered through deep ROSAT observations and identified with a galaxy with a strong but narrow Lyα emission line at z = 2.35. In order to constrain the hard-X-ray properties we observed RXJ 13434+0001 with ASCA. The main purpose is to study the origin of the X-ray emission observed with ROSAT. If it is a scattered component from a strongly absorbed AGN, we could see it much brighter in the hard X-ray band.

Ion-acoustic waves in the auroral plasma

1969 ◽  
Vol 47 (24) ◽  
pp. 2797-2803 ◽  
Author(s):  
J. Hofstee ◽  
P. A. Forsyth
Keyword(s):  
Radio Wave ◽  
Acoustic Waves ◽  
Wave Scattering ◽  
Prominent Feature ◽  
Ion Acoustic Waves ◽  
Auroral Plasma ◽  
Ion Acoustic ◽  
Radio Systems ◽  
Spectrum Characteristic ◽  
Scattered Component

Two coherent bistatic radio systems were used to observe auroral radio reflections under geometrical conditions which would favor the detection of ion-acoustic waves in the auroral ionization. The displaced "line" spectrum, characteristic of scattering by ion-acoustic waves, was a prominent feature of some of the observations but the strength of the wave-scattered component varied widely relative to the non-wave-scattered components. It is concluded that ion-acoustic waves do indeed occur in the auroral plasma but that such waves cannot be the only source of radio-wave scattering in aurora.

scholarly journals Recovering Long-term Aerosol Optical Depth Series (1976–2012) from an Astronomical Potassium-based Resonance Scattering Spectrometer

2014 ◽  
Vol 7 (4) ◽  
pp. 4093-4121 ◽  
Author(s):  
A. Barreto ◽  
E. Cuevas ◽  
P. Pallé ◽  
P. M. Romero ◽  
F. Almansa ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Correlation Coefficients ◽  
Resonant Scattering ◽  
Resonance Scattering ◽  
Data Series ◽  
Long Term Stability ◽  
Filter Radiometer ◽  
Scattered Component

Abstract. A 37 year long-term series of monochromatic Aerosol Optical Depth (AOD) has been recovered from solar irradiance measurements performed with the solar spectrometer Mark-I, deployed at Izaña mountain since 1976. The instrument operation is based on the method of resonant scattering, which presents a long-term stability and high precision in comparison to other instruments based on interference filters. However, it has been specifically designed as a reference instrument for helioseismology, and its ability to determine AOD from transmitted and scattered monochromatic radiation at 769.9 nm inside a potassium vapor cell in the presence of a permanent magnetic field is evaluated in this paper. Particularly, the use of an exposed mirrors arrangement to collect sunlight as well as the Sun-laboratory velocity dependence of the scattered component introduces some inconveniences when we perform the instrument's calibration. We have solved this problem using a quasi-continuous Langley calibration technique and a refinement procedure to correct for calibration errors as well as for the fictitious diurnal cycle on AOD data. Our results showed that calibration errors associated to the quasi-continuous Langley technique are not dependent on aerosol load, provided aerosol concentration remains constant throughout the day, assuring the validity of this technique for those periods with relatively high aerosol content required to calibrate the scattered component. The comparative analysis between the recovered AOD dataset from Mark-I and collocated quasi-simultaneous data from Cimel AErosol RObotic NETwork (AERONET) and Precision Filter Radiometer (PFR) instruments showed an absolute mean bias ≤ 0.01 in the 11 year and 12 year comparison, respectively. High correlation coefficients between AERONET/Mark-I and PFR/Mark-I pairs confirmed a very good linear relationship between instruments, proving that recovered AOD data series from Mark-I can be used together PFR and AERONET AOD data to build a long-term AOD data series at Izaña site (1976–now), suitable for future analysis of aerosols trends and inter-annual variability. Finally, the AOD preliminary trend analysis in the 29 year period from 1984 to 2012 with Mark-I AOD revealed no significant trends. However, we detected a negative significant trend of 0.047 decade−1 during the period 1984–1993.

scholarly journals BAT AGN Spectroscopic Survey XXVII: scattered X-Ray radiation in obscured active galactic nuclei

2021 ◽  
Vol 504 (1) ◽  
pp. 428-443
Author(s):  
K K Gupta ◽  
C Ricci ◽  
A Tortosa ◽  
Y Ueda ◽  
T Kawamuro ◽  
...  
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Negative Correlation ◽  
Scattered Radiation ◽  
Column Density ◽  
Galactic Nuclei ◽  
Significant Negative Correlation ◽  
Black Hole Mass ◽  
X Ray ◽  
Scattered Component

ABSTRACT Accreting supermassive black holes (SMBHs), also known as active galactic nuclei (AGN), are generally surrounded by large amounts of gas and dust. This surrounding material reprocesses the primary X-ray emission produced close to the SMBH and gives rise to several components in the broadband X-ray spectra of AGN, including a power-law possibly associated with Thomson-scattered radiation. In this work, we study the properties of this scattered component for a sample of 386 hard-X-ray-selected, nearby ($z\sim0.03$) obscured AGN from the 70-month Swift/BAT catalogue. We investigate how the fraction of Thomson-scattered radiation correlates with different physical properties of AGN, such as line-of-sight column density, X-ray luminosity, black hole mass, and Eddington ratio. We find a significant negative correlation between the scattering fraction and the column density. Based on a large number of spectral simulations, we exclude the possibility that this anticorrelation is due to degeneracies between the parameters. The negative correlation also persists when considering different ranges of luminosity, black hole mass, and Eddington ratio. We discuss how this correlation might be either due to the angle dependence of the Thomson cross-section or to more obscured sources having a higher covering factor of the torus. We also find a positive correlation between the scattering fraction and the ratio of [O iii] λ5007 to X-ray luminosity. This result is consistent with previous studies and suggests that the Thomson-scattered component is associated with the narrow-line region.

The Calculation Method for Light Climate Parameters Based on Sun-Lighting Efficiency and the Comparative Analysis of Light Climate in Hanoi and Moscow

2019 ◽  
pp. 67-71
Author(s):  
Aleksei K. Solovyov ◽  
Thi Hanh Phuong Nguyen
Keyword(s):  
Comparative Analysis ◽  
Water Vapour ◽  
Calculation Method ◽  
Human Activities ◽  
The Sun ◽  
Light Climate ◽  
High Altitudes ◽  
Distribution Uniformity ◽  
High Level ◽  
Scattered Component

The main source of daylight is the Sun. The EarthТs atmosphere scatters its light due to the air, water vapour, ice particles (at high altitudes), dust, various gases, and other contaminants that appear in the air as a result of human activities. This forms a daylight diffuse (scattered) component, which is a data basis for calculation of daylight in buildings. This basis has its own features for a given region. This article shows a calculation of sun-lighting efficiency in Vietnam. We obtained a variation of horizontal daylight illuminance in Hanoi (21.03∞N). Comparing it with the variation of horizontal daylight illuminance in Moscow (55.70∞N), we can see a high level and a distribution uniformity of outdoor illuminance in Vietnam. The maximum levels of diffuse illuminance and total illuminance in Hanoi are 45.2 and 58.52 klx; the maximum levels of diffuse illuminance and total illuminance in Moscow are 28.3 and 53.1 klx. Besides, illuminance levels in winter months are much higher for Hanoi than for Moscow. This can be explained by different latitudes of these cities and by the Sun motion.

Scanning Transmission Energy Analyzing Microscope (“STEAM”)

1974 ◽  
Vol 32 ◽  
pp. 440-441
Author(s):  
Jack A. Horner
Keyword(s):  
Resolution Enhancement ◽  
Energy Losses ◽  
Thin Sections ◽  
X Ray ◽  
The Past ◽  
Recent Interest ◽  
Scanning Transmission ◽  
Electron Energy Loss ◽  
Scattered Component ◽  
Transmission Energy

The use of electron energy loss analyzers has been rather extensive in recent years. Most analyzers have been designed to discriminate losses in the range 0 < ΔE < 100eV or to reject the inelastically scattered component of transmitted beams for the purpose of contrast and resolution enhancement. More recent interest has been directed towards detection of energy losses associated with inner shell ionizations, simultaneous with characteristic X-ray emission. Such an apparatus has been under development in this laboratory for the past 2½ years. The design and use of this device for elemental analysis in thin sections is described.

Determination of x-ray spectra and of the scattered component up to 300 kV

1991 ◽  
Vol 18 (5) ◽  
pp. 934-938 ◽  
Author(s):  
R. F. Laitano ◽  
R. Pani ◽  
R. Pellegrini
Keyword(s):  
X Ray ◽  
Scattered Component
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