Suitability of Gadolinium Based Systems for X-Ray Real Time Radiography.  [c.443]

A typical RTR system consists of a image intensifier, CCD camera, image processor and high resolution TV monitor in addition to radiographic source. Image intensifiers used in X-radiography employ Csl as the input detector. With the increased use of neutrons as radiation source, real time neutron radiography is also being practised widely. Image intensifiers used in neutron radiography employ gadolinium as the input screen. Typical resolutions attainable with present day X-ray and neutron image intensifiers is of the order 45 Ip/cm in the nornial mode. It is well known that rare earth screens such as gadolinium oxysulphide are sensitive to photons as well. While such screens have been used in fluoroscopy, no systematic study has been made to evaluate their potential usage for real time applications using X-rays. One possible reason for this could be due to their non-linear response over the X-ray energy range. A systematic study was undertaken by the authors to study the resolution and sensitivities achievable on using Gadolinium based image intensifier systems along with X-rays as the source of radiation. Both performance curves and contrast response curves of such systems were experimentally detennined which is presented in this paper.  [c.443]

Detectors for the tliree types of radiation are similar and may be classified in two categories, photographic and electronic. In addition to photographic films and plates, photographic detectors also include fluorescent screens and image plates, in which x-rays produce a latent image in a storage phosphor. In the dark the phosphor emits radiation very slowly, but exposure to light from a laser stimulates fluorescence, which then can be observed by a photomultiplier tube and converted to an electronic signal. Because neutrons interact weakly with most materials, image plates and fluorescent screens must contain one of the elements, such as gadolinium, that have isotopes with high absorption cross-sections. Photographic detection of neutrons usually uses a fluorescent screen to enliance the image.  [c.1379]

Another characteristic change across the lanthanide series is that of the paramagnetism of the ions this rises to a maximum at neodymium, then falls to samarium, then rises to a second maximum at gadolinium before falling finally to zero at the end of the series.  [c.442]

Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are commercially important. With the development of ion-exchange and solvent extraction techniques, the availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium.  [c.187]

Gadolinium has the highest thermal neutron capture cross-section of any known element (49,000 barns).  [c.188]

Gadolinium yttrium garnets are used in microwave applications and gadolinium compounds are used as phosphors in color television sets.  [c.188]

The metal has unusual superconductive properties. As little as 1 percent gadolinium improves the workability and resistance of iron, chromium, and related alloys to high temperatures and oxidation.  [c.188]

Gadolinium ethyl sulfate has extremely low noise characteristics and may find use in duplicating the performance of amplifiers, such as the maser.  [c.188]

In certain situations involving coherently interacting pairs of transition dipoles, the initial fluorescence anisotropy value is expected to be larger tlian 0.4. As mdicated by the theory described by Wyime and Hochstrasser [, and by Knox and Gtilen [, ], the initial anisotropy expected for a pair of coupled dipoles oriented 90° apart, as an example.  [c.1979]

GETELM Reads and echo prints element connectivity formatting should match the output generated by the pre-processor.  [c.212]

Ytterby, a village in Sweden near Vauxholm) Yttria, which is an earth containing yttrium, was discovered by Gadolin in 1794. Ytterby is the site of a quarry which yielded many unusual minerals containing rare earths and other elements. This small town, near Stockholm, bears the honor of giving names to erbium, terbium, and ytterbium as well as yttrium.  [c.73]

Yttrium iron, aluminum, and gadolinium garnets, with formulas such as Y3FesOi2 and Y3AI5O12, have interesting magnetic properties. Yttrium iron garnet is also exceptionally efficient as both a transmitter and transducer of acoustic energy. Yttrium aluminum garnet, with a hardness of 8.5, is also finding use as a gemstone (simulated diamond).  [c.74]

Europe) In 1890 Boisbaudran obtained basic fractions from samarium-gadolinium concentrates which had spark spectral lines not accounted for by samarium or gadolinium. These lines subsequently have been shown to belong to europium. The discovery of europium is generally credited to Demarcay, who separated the rare earth in reasonably pure form in 1901. The pure metal was not isolated until recent years.  [c.177]

From gadolinite, a mineral named for Gadolin, a Finnish chemist. The rare earth metal is obtained from the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by Marignac in 1880 and Lecoq de Boisbaudran independently isolated it from Mosander s yttria in 1886.  [c.187]

Natural gadolinium is a mixture of seven isotopes, but 17 isotopes of gadolinium are now recognized. Although two of these, 155Gd and 157Gd, have excellent capture characteristics, they are only present naturally in low concentrations. As a result, gadolinium has a very fast burnout rate and has limited use as a nuclear control rod material.  [c.187]

As with other related rare-earth metals, gadolinium is silvery white, has a metallic luster, and is malleable and ductile. At room temperature, gadolinium crystallizes in the hexagonal, close-packed alpha form. Upon heating to 1235oG, alpha gadolinium transforms into the beta form, which has a body-centered cubic structure.  [c.187]

The metal is ferromagnetic. Gadolinium is unique for its high magnetic movement and for its special Gurie temperature (above which ferromagnetism vanishes) lying just at room temperature. This suggests applications as a magnetic component that can sense hot and cold.  [c.188]

See pages that mention the term Gadolinium : [c.45]    [c.185]    [c.185]    [c.188]    [c.235]    [c.444]    [c.224]    [c.245]    [c.187]    [c.187]    [c.188]    [c.207]    [c.217]    [c.53]    [c.241]    [c.278]    [c.306]    [c.320]    [c.348]    [c.357]    [c.372]    [c.623]    [c.659]    [c.719]    [c.837]    [c.845]    [c.911]    [c.912]    [c.913]    [c.1184]    [c.430]    [c.430]   
Chemistry of the elements (1998) -- [ c.1229 ]