Growth of large diameter pure phase wurtzite GaP nanowires by a two-step axial-radial growth approach

2018 ◽  
Vol 112 (13) ◽  
pp. 133107 ◽  
Author(s):  
Nripendra N. Halder ◽  
Shimon Cohen ◽  
David Gershoni ◽  
Dan Ritter
Keyword(s):  
Radial Growth ◽  
Large Diameter ◽  
Pure Phase ◽  
Growth Approach

Susceptibility of white spruce to attack by spruce beetles during the early years of an outbreak in Alaska

1983 ◽  
Vol 13 (4) ◽  
pp. 678-684 ◽  
Author(s):  
John S. Hard ◽  
Richard A. Werner ◽  
Edward H. Holsten
Keyword(s):  
Radial Growth ◽  
Large Diameter ◽  
White Spruce ◽  
Early Years ◽  
Kenai Peninsula ◽  
Spruce Beetle ◽  
Southcentral Alaska ◽  
Percent Mortality ◽  
Rating Model ◽  
Hazard Rating

Twenty-five variable sample plots were examined in mature white spruce (Piceaglauca (Moench) Voss) stands, in southcentral Alaska. These stands, located in the Canyon Creek – Quartz Creek valley on the Kenai Peninsula, have been infested by spruce beetle, Dendroctonusrufipennis (Kirby), since 1978. Diameter was not an important criterion for spruce susceptibility to attack or death unless large diameter was coupled with slower than average radial growth in the last 5 years, an apparent indicator of current tree vigor. A sigmoid transformation of percent mortality of spruce was inversely related to the logarithm of mean cumulative radial growth of spruce in the last 5 years and was directly related to number of spruce per hectare greater than 24.1 cm in diameter. This relationship is portrayed graphically as a rudimentary stand hazard rating model.

The role of differential phase contrast in electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 176-177
Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier
Keyword(s):  
Phase Contrast ◽  
Practical Method ◽  
Position Vector ◽  
Differential Phase ◽  
Pure Phase ◽  
Differential Phase Contrast ◽  
The Difference ◽  
Image Position ◽  
First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

Development of a digital SEM

1991 ◽  
Vol 49 ◽  
pp. 358-359
Author(s):  
A. Yamada ◽  
A. Shibano ◽  
K. Harasawa ◽  
T. Kobayashi ◽  
H. Fukuda ◽  
...  
Keyword(s):  
Large Diameter ◽  
Objective Lens ◽  
Large Specimen ◽  
Backscattered Electrons ◽  
Digital Scanning ◽  
Junction Type ◽  
High Resolution Images ◽  
Working Distance ◽  
Type Detector ◽  
Short Working

A newly developed digital scanning electron microscope, the JSM-6300, has the following features: Equipped with a narrower conical objective lens (OL), it allows high resolution images to be obtained easily at a short working distance (WD) and a large specimen tilt angle. In addition, it is provided with automatic functions and digital image processing functions for ease of operation.Conical C-F lens: The newly developed conical C-F objective lens, having low aberration characteristics over a wide WD range, allows a large-diameter (3-inch) specimen to be tilted up to 60° at short WD, and provides images with low magnifications starting at 10*. On the bottom of the lens, a p n junction type detector is provided to detect backscattered electrons (BE) from the specimen. As the narrower conical 0L increases the secondary electron (SE) detector's field intensity on the specimen surface, high SE image quality is obtained.

CALCULATION OF STAGES OF THE TECHNOLOGICAL PROCESS OF MANUFACTURE OF PPD DETECTORS USING COMPUTER MATHEMATICAL MODELING AND PRODUCTION OF ALPHA RADIOMETER ON THEIR BASIS

2020 ◽  
Vol 7 (2) ◽  
pp. 21-28
Author(s):  
SALI RADZHAPOV ◽  
◽  
RUSTAM RAKHIMOV ◽  
BEGJAN RADZHAPOV ◽  
MARS ZUFAROV
Keyword(s):  
Mathematical Modeling ◽  
Technological Process ◽  
Block Diagram ◽  
Large Diameter ◽  
Silicon Detector ◽  
Digital Processing ◽  
Main Element ◽  
Alpha Radiation ◽  
Initial Silicon ◽  
Natural Isotopes

The article describes the developed radiometer for Express measurement of alpha radiation of radioactive elements based on a large-diameter silicon detector. The main element of the PPD detector is made using computer mathematical modeling of all stages of the technological process of manufacturing detectors, taking into account at each stage the degree of influence of the properties of the initial silicon on the electrophysical and radiometric characteristics of the detector. Detectors are manufactured for certain types of devices. The developed radiometer is designed to measure alpha radiation of natural isotopes (238U, 234U, 232Th, 226Ra, 222Rn, 218Po, 214Bi, etc.) in various environments. It also shows the principle of operation of the device, provides a block diagram of the measuring complex, describes the electronic components of the radiometer, as well as the block diagram. Signal transformations (spectrum transfer, filtering, accumulation) are implemented programmatically on the basis of a digital processing module. The device can detect the presence of specific elements in various environments, as well as protect people from the harmful effects of adverse radiation and can be used both in the field and stationary.

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