scholarly journals First negative system of N<sub>2</sub><sup>+</sup> in aurora: simultaneous space-borne and ground-based measurements and modeling results

2014 ◽  
Vol 32 (5) ◽  
pp. 499-506 ◽  
Author(s):  
K. Axelsson ◽  
T. Sergienko ◽  
H. Nilsson ◽  
U. Brändström ◽  
K. Asamura ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Electron Flux ◽  
Imaging System ◽  
Electron Excitation ◽  
Absolute Calibration ◽  
Simultaneous Measurements ◽  
Auroral Emission ◽  
Negative System ◽  
Correct Comparison

Abstract. The auroral emission of the first negative system of N2+ at 427.8 nm is analyzed using simultaneous measurements from the ground with ALIS (Auroral Large Imaging System) and from space with optical (MAC) and particle (ESA) instruments of the Reimei satellite. The study has two main objectives. The first is validation of the absolute calibration of the ALIS and the Reimei MAC cameras. The other task is to evaluate different cross sections of the electron excitation of N2+ that are used for the modeling of the auroral 1N system emissions. The simultaneous measurements of the 427.8 nm emission by ALIS and Reimei imagers show excellent agreement, indicating that the calibration of the two instruments is correct. Comparison of the 427.8 nm emission intensity calculated using the incident electron flux measured by the Reimei particle instruments with intensities measured by the optical imagers show that the best match is reached with the cross section from Shemansky and Liu (2005).

Energy Loss Imaging in Biology

1982 ◽  
Vol 40 ◽  
pp. 416-419
Author(s):  
H. Shuman ◽  
A.V. Somlyo ◽  
A.P. Somlyo ◽  
T. Frey ◽  
D. Safer
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Cross Section ◽  
Cross Sections ◽  
Count Rate ◽  
Electron Flux ◽  
Characteristic Energy ◽  
Spectrometer Slit ◽  
Electron Energy Loss ◽  
Sensitive Method

It has been recognized for sometime that electron energy loss spectroscopy (EELS) is potentially the most sensitive method of measuring elemental composition in the electron microscope. Magnetic sector spectrometers currently in use collect most of the inelastically scattered electrons, while the cross sections for ionization of the L2 3 levels of the biologically important elements are large. The energies of the theoretically predicted L2 3 absorption edge maxima and their corresponding differential cross section for lOmrad collection and 80keV incident electrons are shown in Table I. The characteristic energy loss electron count rate expected from one atom with lOeV spectrometer slit width and lOOA/cm2 (the maximum available from a tungsten hairpin) electron flux at the specimen, indicates that the minimum detectable mass sensitivity of EELS will be high. An experimentally determined count rate and cross section for the Fe M2, 3 edge was determined from the ferritin images shown in Fig. 1.

SLOW ELECTRONS PENETRATION IN GOLD AT NORMAL AND OBLIQUE ANGLES OF INCIDENCE

2005 ◽  
Vol 19 (11) ◽  
pp. 1955-1963 ◽  
Author(s):  
Z. CHAOUI ◽  
N. BOUARISSA
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Valence Electron ◽  
Electron Excitation ◽  
Angle Of Incidence ◽  
Backscattering Coefficient ◽  
Implantation Depth ◽  
Frame Work ◽  
Slow Electrons ◽  
Scattering Cross Sections

Electron penetration in semi-infinite Au for normal and oblique angles of incidence at energies between 0.5 and 4 keV is simulated within a Monte-Carlo frame work. The elastic scattering cross sections have been obtained from a modified Rutherford differential cross section, whereas inelastic core and valence electron excitation are calculated using the Gryzinski's expression. The dependence of the backscattering coefficient, mean implantation depth and stopping profiles on the angle of incidence has been examined. These quantities are found to be significantly enhanced as the angle of incidence becomes higher which is generally in consistent with previous simulations.

Electron Excitation in Noble Gases

1975 ◽  
Vol 53 (7) ◽  
pp. 689-699 ◽  
Author(s):  
H. G. P. Lins De Barros ◽  
H. S. Brandi
Keyword(s):  
Differential Cross Section ◽  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Noble Gases ◽  
Electron Excitation ◽  
Wave Functions ◽  
Total Cross Sections ◽  
Collision Processes

Calculations for cross sections for some states of Ne excited by electron impact have been carried out. A parametrization of total and differential cross section in the Born–Ochkur approximation has been proposed. Using this parametrization and appropriate wave functions for the states involved in the collision processes, differential and total cross sections have been calculated. The results have shown that this parametrization is very convenient to study this type of problem.

Electron Excitation of 21S, 23S, 21P, and 23P States of Helium

1975 ◽  
Vol 53 (20) ◽  
pp. 2289-2295 ◽  
Author(s):  
H. G. P. Lins de Barros ◽  
H. S. Brandi
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Amplitude ◽  
Theoretical Calculations ◽  
Electron Excitation ◽  
Wave Functions ◽  
Excitation Cross Sections ◽  
Characteristic Values ◽  
The One

Calculations for the total excitation cross sections of the 21S, 23S, 21P, and 23P states of He by electron impact have been carried out assuming the Born–Ochkur approximation for the scattering amplitude and a parametrization previously proposed by the authors for the total cross section. For the atomic wave functions we used LS coupling and obtained the one electron orbitals using the Xα method for three characteristic values of the parameter α. The results are compared with other experimental and theoretical calculations.

Absolute Calibration of Small-Angle Neutron Scattering Data of a Double-Crystal Diffractometer

1997 ◽  
Vol 30 (5) ◽  
pp. 857-861 ◽  
Author(s):  
F. Carsughi ◽  
D. Bellmann ◽  
J. Kulda ◽  
M. Magnani ◽  
M. Stefanon
Keyword(s):  
Neutron Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Data ◽  
Absolute Calibration ◽  
Double Crystal ◽  
Similar Materials ◽  
Double Crystal Diffractometer

Small-angle neutron scattering (SANS) experiments generally provide the absolute SANS cross sections and this allows quantitative results to be obtained; however, data collected at double-crystal diffractometers are frequently not normalized to absolute cross sections and they are used only for qualitative analysis. In point-geometry diffractometers, the normalization is done by comparing the scattered intensities to those of samples of known cross sections or by measuring the direct-beam intensity; in the double-crystal diffractometer, the incident flux information is contained in the rocking curve measured without a sample and this feature can therefore be used to normalize the scattered intensities to the SANS cross sections. A sample of thickness 1 mm of the Ni-based superalloy UDIMET 520 was analyzed at a double-crystal diffractometer; the SANS cross section obtained by the proposed procedure compares well with the SANS cross section found for similar materials by using conventional point-geometry diffractometers and calibrated by light water.

scholarly journals New and Old Measurements of Electron Scattering in Atomic Hydrogen

1998 ◽  
Vol 51 (4) ◽  
pp. 633 ◽  
Author(s):  
J. F. Williams
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Atomic Hydrogen ◽  
Intermediate Energy ◽  
Absolute Calibration ◽  
Absolute Cross Section ◽  
Close Coupling ◽  
R Matrix ◽  
Correlation Parameters

A critical look is made of discrepancies and agreements between new and old measurements and theories for elastic and n = 2 excitation of atomic hydrogen by electron impact, mainly at 16·5, 54 and 100 eV. A discussion of earlier work indicates the contributions of Weigold and colleagues. The diffculties of observing and modelling small scattered fluxes at backward scattering angles and of making absolute cross section calibrations are noted. New measurements of elastic scattering at 16·5 eV confirm earlier measured angular distributions. An absolute calibration of the differential cross section at 16·5 eV gives agreement within one standard deviation with intermediate energy R-matrix and multi-pseudostate close coupling values. At 16·5 eV, measurements of the separate 2s and 2p differential cross sections and the lambda, R and I correlation parameters again support the values from those theories.

scholarly journals Absolute Calibration of Jason-1 and Envisat Altimeter Ku-Band Radar Cross Sections from Cross Comparison with TRMM Precipitation Radar Measurements

2005 ◽  
Vol 22 (9) ◽  
pp. 1389-1402 ◽  
Author(s):  
N. Tran ◽  
O-Z. Zanife ◽  
B. Chapron ◽  
D. Vandemark ◽  
P. Vincent
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Calibration ◽  
Precipitation Radar ◽  
Radar Cross Sections ◽  
Trmm Precipitation ◽  
Radar Calibration ◽  
One Year ◽  
Rain Radar ◽  
Ku Band

Abstract One year of collocated, rain-free nadir Ku-band backscatter cross-section measurements from the Tropical Rainfall Mapping Mission (TRMM) precipitation radar (PR) and both Jason-1 and Envisat RA-2 altimeter measurements have been compiled to compare these three sources of Ku-band radar cross section. With the exception of a +1.46 dB relative offset between Jason-1 and PR measurements and a −1.40 dB offset between Envisat and PR ones, all three Ku-band measurements compare very well in terms of dependencies upon model wind speed estimates and significant wave height measurements. The altimeter radars and the rain radar thus provide consistent measurements, and observed biases can be rationalized as differences in the radar calibration. The precipitation radar, which also covers off-nadir measurements, has been absolutely calibrated using an active radar calibrator. Consequently, the observed relative offsets can be used to indirectly calibrate both Jason-1 and Envisat altimeter Ku-band radar cross sections in an absolute sense.

Sign in / Sign up

Export Citation Format

Share Document