Neutron-Induced Particle Track Mapping of Elemental Distributions

1986 ◽  
Vol 69 ◽  
Author(s):  
R. W. Bild
Keyword(s):  
Spatial Resolution ◽  
Fission Fragment ◽  
Charged Particles ◽  
Thermal Neutrons ◽  
Reaction Products ◽  
Particle Track ◽  
Target Element ◽  
Detector Materials ◽  
Better Than

AbstractThermal neutrons are captured by several elements which emit charged particles as reaction products. These particles leave etchable damage tracks in detector materials placed against a sample, creating a map of the distribution and concentration of the target element. The most common applications are for trace U using fission fragment tracks and B using alpha tracks. Li, N and possibly S and O can also be determined. We have applied the technique to B in metals and coatings, Li in Al, N in glass and U in O-ring seals. Dectection limits are better than 10−11g/g for U, 10−9g/g for B, 10−6 g/g for Li and 0.1 wt % for N. Spatial resolution for mapping is about 25 μm.

Precipitation in silicon: Microanalysis

1988 ◽  
Vol 46 ◽  
pp. 474-475
Author(s):  
R.W. Carpenter
Keyword(s):  
Transition Metals ◽  
Spatial Resolution ◽  
Thin Foil ◽  
Precipitation Reaction ◽  
High Current ◽  
Reaction Products ◽  
Carbon And Nitrogen ◽  
Dielectric Layers ◽  
Precipitation Processes ◽  
Areas Of Interest

Interest in precipitation processes in silicon appears to be centered on transition metals (for intrinsic and extrinsic gettering), and oxygen and carbon in thermally aged materials, and on oxygen, carbon, and nitrogen in ion implanted materials to form buried dielectric layers. A steadily increasing number of applications of microanalysis to these problems are appearing. but still far less than the number of imaging/diffraction investigations. Microanalysis applications appear to be paced by instrumentation development. The precipitation reaction products are small and the presence of carbon is often an important consideration. Small high current probes are important and cryogenic specimen holders are required for consistent suppression of contamination buildup on specimen areas of interest. Focussed probes useful for microanalysis should be in the range of 0.1 to 1nA, and estimates of spatial resolution to be expected for thin foil specimens can be made from the curves shown in Fig. 1.

A method of precise misorientation determination

2003 ◽  
Vol 36 (6) ◽  
pp. 1319-1323 ◽  
Author(s):  
A. Morawiec
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spatial Resolution ◽  
Standard Procedure ◽  
Good Spatial Resolution ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Achievable Accuracy ◽  
Better Than

A method that improves the accuracy of misorientations determined from Kikuchi patterns is described. It is based on the fact that some parameters of a misorientation calculated from two orientations are more accurate than other parameters. A procedure which eliminates inaccurate elements is devised. It requires at least two foil inclinations. The quality of the approach relies on the possibility to set large sample-to-detector distances and the availability of good spatial resolution of transmission electron microscopy. Achievable accuracy is one order of magnitude better than the accuracy of the standard procedure.

scholarly journals Global downscaling of remotely sensed soil moisture using neural networks

2018 ◽  
Vol 22 (10) ◽  
pp. 5341-5356 ◽  
Author(s):  
Seyed Hamed Alemohammad ◽  
Jana Kolassa ◽  
Catherine Prigent ◽  
Filipe Aires ◽  
Pierre Gentine
Keyword(s):  
Soil Moisture ◽  
Spatial Resolution ◽  
Land Surface ◽  
Vegetation Index ◽  
Spatial Scales ◽  
Ancillary Data ◽  
Repeat Time ◽  
Spatiotemporal Scales ◽  
Better Than

Abstract. Characterizing soil moisture at spatiotemporal scales relevant to land surface processes (i.e., of the order of 1 km) is necessary in order to quantify its role in regional feedbacks between the land surface and the atmospheric boundary layer. Moreover, several applications such as agricultural management can benefit from soil moisture information at fine spatial scales. Soil moisture estimates from current satellite missions have a reasonably good temporal revisit over the globe (2–3-day repeat time); however, their finest spatial resolution is 9 km. NASA's Soil Moisture Active Passive (SMAP) satellite has estimated soil moisture at two different spatial scales of 36 and 9 km since April 2015. In this study, we develop a neural-network-based downscaling algorithm using SMAP observations and disaggregate soil moisture to 2.25 km spatial resolution. Our approach uses the mean monthly Normalized Differenced Vegetation Index (NDVI) as ancillary data to quantify the subpixel heterogeneity of soil moisture. Evaluation of the downscaled soil moisture estimates against in situ observations shows that their accuracy is better than or equal to the SMAP 9 km soil moisture estimates.

Rings of Uranus: A Review of Occultation Results

1982 ◽  
Vol 60 ◽  
pp. 237-256 ◽  
Author(s):  
James L. Elliot
Keyword(s):  
Spatial Resolution ◽  
Particle Collisions ◽  
Dynamical Models ◽  
High Resolution Data ◽  
Unique System ◽  
Structural Details ◽  
The Mean ◽  
Geometric Albedo ◽  
Resolution Data ◽  
Better Than

Since their discovery in 1977 (Elliot 1979), the dark, narrow rings of Uranus have intrigued dynamicists. The main enigma has been how the rings can remain so narrow - only a few km wide - when particle collisions and the Poynting-Robertson effect should cause the particles to disperse. The Uranian rings have posed other problems as well, and have proved to be a unique system for developing dynamical models of rings. The reason for this theoretical interest is the high precision and time coverage of the data available from occultation observations. With occultations we obtain a spatial resolution of 1 km in the position of ring segments and a resolution of 4 km in their structural details. These high-resolution data are available sufficiently often to be useful for dynamical purposes - at the rate of 1-2 events per year. This spatial resolution is somewhat better than that obtained by Voyager imaging of Jupiter’s and Saturn’s rings (Owen et al. 1979; Smith et al. 1981). Ground-based images of the Uranian rings, obtained by Matthews, Nicholson, and Neugebauer (1981), have a spatial resolution of ~50,000 km. Although unable to resolve individual rings, these data have established the mean geometric albedo of the rings at 0.030 ± 0.005.

scholarly journals KM3NeT acoustic positioning and detection system

2019 ◽  
Vol 216 ◽  
pp. 02006 ◽  
Author(s):  
Salvatore Viola
Keyword(s):  
Cherenkov Radiation ◽  
Detection System ◽  
Charged Particles ◽  
Positioning System ◽  
Atmospheric Neutrinos ◽  
Neutrino Telescopes ◽  
Strongly Connected ◽  
Radiation Induced ◽  
Better Than ◽  
Acoustic Positioning

In the Mediterranean Sea, the KM3NeT Collaboration is constructing a the deep-sea research infrastructure hosting next generation neutrino telescopes. In the KM3NeT telescopes the Cherenkov radiation induced by the secondary charged particles produced in the interaction of cosmic and atmospheric neutrinos within an effective volume between megaton and several cubic kilometers of water are detected by an array of thousands of photomultipliers. The capability of the telescope to determine the direction of secondary charged particles and to point back to the neutrino source is strongly connected to the accuracy on photomultipliers positions. In KM3NeT, the photomultiplier positions are continuously monitored by an acoustic positioning system, designed by the KM3NeT Collaboration to reach an accuracy of the photomultiplier positions better than 20 cm.

Optimal Detection Sensitivities in Activation with Fast Neutrons from an 241Am-242Cm—Be Source

1969 ◽  
Vol 23 (1) ◽  
pp. 5-7 ◽  
Author(s):  
James Wing ◽  
Morris A. Wahlgren
Keyword(s):  
Sodium Iodide ◽  
Chemical Elements ◽  
Fast Neutrons ◽  
Total Output ◽  
Thermal Neutrons ◽  
Optimal Detection ◽  
Target Element ◽  
Product Nuclide ◽  
Short Product ◽  
Iodide Crystal

The detection sensitivities of 60 chemical elements in activation with the fast neutrons from an 241Am-242Cm—Be source have been measured. The source consisted of six slugs with a total output of 4.8X109 unmoderated neutrons/sec, and a flux of 1.4×108 fast neutrons/sec-cm2. In general, the sensitivity (counts in a selected photopeak per gram of target element) for each element was obtained with irradiation for two to three half-lives of the short product nuclide, and counting for the same length of time. Neither irradiation nor counting was longer than 1 h. The detector was a cylindrical thallium-activated sodium iodide crystal 10 cm long and 10 cm in diam. The measured sensitivities are compared with reported sensitivities in activation with thermal neutrons.

Microscopic Observation of Photocatalytic Reaction Using Microelectrode: Spatial Resolution for Reaction Products Distribution

1995 ◽  
Vol 24 (11) ◽  
pp. 979-980 ◽  
Author(s):  
Katsuyoshi Ikeda ◽  
Hideki Sakai ◽  
Ryo Baba ◽  
Kazuhito Hashimoto ◽  
Akira Fujishima
Keyword(s):  
Spatial Resolution ◽  
Microscopic Observation ◽  
Photocatalytic Reaction ◽  
Reaction Products

scholarly journals The insulin A and B chains contain structural information for the formation of the native molecule. Studies with protein disulphide-isomerase

1990 ◽  
Vol 268 (2) ◽  
pp. 429-435 ◽  
Author(s):  
J G Tang ◽  
C L Tsou
Keyword(s):  
Structural Information ◽  
Sufficient Information ◽  
Appreciable Effect ◽  
Dilute Solution ◽  
Reaction Products ◽  
C Peptide ◽  
Native Insulin ◽  
Predominant Product ◽  
Better Than

It has been shown previously [Tang, Wang & Tsou (1988) Biochem. J. 255, 451-455] that, under appropriate conditions, native insulin can be obtained from scrambled insulin or the S-sulphonates of the chains with a yield of 25-30%, together with reaction products containing the separated A and B chains. The native hormone is by far the predominant product among the isomers containing both chains. It is now shown that the presence of added C peptide has no appreciable effect on the yield of native insulin. At higher temperatures the content of the native hormone decreases whereas those of the separated chains increase, and in no case was scrambled insulin containing both chains the predominant product in the absence of denaturants. Both the scrambling and the unscrambling reactions give similar h.p.l.c. profiles for the products. Under similar conditions cross-linked insulin with native disulphide linkages can be obtained from the scrambled molecule or from the S-sulphonate derivative with yields of 50% and 75% respectively at 4 degrees C, and with a dilute solution of the hexa-S-sulphonate yields better than 90% can be obtained. The regenerated product is shown to have the native disulphide bridges by treatment with CNBr to give insulin and by the identity of the h.p.l.c. profile of its peptic hydrolysate with that for cross-linked insulin. It appears that the insulin A and B chains contain sufficient information for the formation of the native molecule and that the role of the connecting C peptide is to bring and to keep the two chains together.

Towards a microchannel-based X-ray detector with two-dimensional spatial and time resolution and high dynamic range

2015 ◽  
Vol 22 (5) ◽  
pp. 1202-1206 ◽  
Author(s):  
Bernhard W. Adams ◽  
Anil U. Mane ◽  
Jeffrey W. Elam ◽  
Razib Obaid ◽  
Matthew Wetstein ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Time Resolution ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
High Time Resolution ◽  
Two Dimensional ◽  
X Ray ◽  
High Dynamic ◽  
Time Gating ◽  
Better Than

X-ray detectors that combine two-dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time-gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter-scale spatial resolution and better than 100 ps time resolution. The technology is capable of continuous streaming of time- and location-tagged events at rates greater than 107events per cm2. Time-gating can be used for improved dynamic range.

scholarly journals Keck laser guide star observations of 11 GOODS-South Chandra sources at z ~ 1

2007 ◽  
Vol 3 (S245) ◽  
pp. 463-464
Author(s):  
S. Mark Ammons ◽  
Jason Melbourne ◽  
David C. Koo ◽  
Claire E. Max
Keyword(s):  
Optical Depth ◽  
Adaptive Optics ◽  
Spatial Resolution ◽  
Rest Frame ◽  
Point Sources ◽  
Laser Guide Star ◽  
The Mean ◽  
Guide Star ◽  
Laser Guide ◽  
Better Than

AbstractThe Center for Adaptive Optics (CfAO) Treasury Survey (CATS) has observed 11 Chandra sources (10 AGN) at z ~ 1 in the GOODS-South field with the laser guide star adaptive optics (LGSAO) system at Keck Observatory. We combine this K band imaging with ACS imaging in the B, V, I, and z bands to obtain multi-color imaging at a spatial resolution better than 100 mas in all bands. We attempt to remove central optical point sources from AGN using the GALFIT (Peng et al. 2002) routine. We fit Bruzual & Charlot (2003) tau-models to the residuals and find young, dusty stellar populations in the central 1-2 kpc (the mean central optical depth at rest-frame 500 nm is 4-5).

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