scholarly journals A Study of Collimator Scatter Factors of Rectangular Irradiation Fields Using the Virtual Source Plane

2010 ◽  
Vol 66 (3) ◽  
pp. 225-230
Author(s):  
Naoki Kinoshita ◽  
Hidekazu Nambu ◽  
Fumiaki Uto ◽  
Eiji Shiba
Keyword(s):  
Source Plane ◽  
Virtual Source ◽  
Collimator Scatter

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

scholarly journals Tutorial on seismic interferometry: Part 2 — Underlying theory and new advances

Geophysics ◽  
2010 ◽  
Vol 75 (5) ◽  
pp. 75A211-75A227 ◽  
Author(s):  
Kees Wapenaar ◽  
Evert Slob ◽  
Roel Snieder ◽  
Andrew Curtis
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Seismic Interferometry ◽  
Virtual Source ◽  
Bending Waves ◽  
Complex Source ◽  
Recent Developments ◽  
Diffusion Phenomena ◽  
Quantum Mechanical Scattering ◽  
Moving Media

In the 1990s, the method of time-reversed acoustics was developed. This method exploits the fact that the acoustic wave equation for a lossless medium is invariant for time reversal. When ultrasonic responses recorded by piezoelectric transducers are reversed in time and fed simultaneously as source signals to the transducers, they focus at the position of the original source, even when the medium is very complex. In seismic interferometry the time-reversed responses are not physically sent into the earth, but they are convolved with other measured responses. The effect is essentially the same: The time-reversed signals focus and create a virtual source which radiates waves into the medium that are subsequently recorded by receivers. A mathematical derivation, based on reciprocity theory, formalizes this principle: The crosscorrelation of responses at two receivers, integrated over differ-ent sources, gives the Green’s function emitted by a virtual source at the position of one of the receivers and observed by the other receiver. This Green’s function representation for seismic interferometry is based on the assumption that the medium is lossless and nonmoving. Recent developments, circumventing these assumptions, include interferometric representations for attenuating and/or moving media, as well as unified representations for waves and diffusion phenomena, bending waves, quantum mechanical scattering, potential fields, elastodynamic, electromagnetic, poroelastic, and electroseismic waves. Significant improvements in the quality of the retrieved Green’s functions have been obtained with interferometry by deconvolution. A trace-by-trace deconvolution process compensates for complex source functions and the attenuation of the medium. Interferometry by multidimensional deconvolution also compensates for the effects of one-sided and/or irregular illumination.

Development of a new virtual source model for portal image prediction using the Monte Carlo code penelope

2014 ◽  
Vol 30 ◽  
pp. e141
Author(s):  
I. Chabert ◽  
D. Lazaro ◽  
E. Barat ◽  
T. Dautremer ◽  
T. Montagu ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Source Model ◽  
Monte Carlo Code ◽  
Virtual Source ◽  
Image Prediction

scholarly journals In phantom determination of collimator scatter factor

1996 ◽  
Vol 23 (7) ◽  
pp. 1207-1212 ◽  
Author(s):  
Kwok L. Lam ◽  
Randall K. Ten Haken
Keyword(s):  
Scatter Factor ◽  
Collimator Scatter Factor ◽  
Collimator Scatter

A consistent formalism for the application of phantom and collimator scatter factors

1999 ◽  
Vol 44 (2) ◽  
pp. 365-381 ◽  
Author(s):  
J L M Venselaar ◽  
J J M van Gasteren ◽  
S Heukelom ◽  
H N Jager ◽  
B J Mijnheer ◽  
...  
Keyword(s):  
Collimator Scatter

scholarly journals The mass profile of early-type galaxies in overdense environments: the case of the double source-plane gravitational lens SL2SJ02176-0513

2009 ◽  
Vol 501 (2) ◽  
pp. 475-484 ◽  
Author(s):  
H. Tu ◽  
R. Gavazzi ◽  
M. Limousin ◽  
R. Cabanac ◽  
P. J. Marshall ◽  
...  
Keyword(s):  
Gravitational Lens ◽  
Source Plane ◽  
Early Type ◽  
Mass Profile
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