Linked Life Data

6727788

Source:http://linkedlifedata.com/resource/pubmed/id/6727788

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1984-6-29
pubmed:abstractText
The charging characteristics of ionographic latent images are discussed in terms of the saturation characteristics of ionographic chambers. It is shown that latent images are essentially foil electrets with surface charge densities modulated by the x-ray transmission through the object. Empirical methods for the calculation of saturation current densities and extrapolated electric fields are given. Both the saturation current density and the extrapolated field consist of two components: one, which is linear with the air gap thickness, is produced by primary photon interactions in the chamber-sensitive volume; the other, exhibiting an exponential saturation, is attributed to photoelectrons backscattered from the polarizing electrode into the chamber-sensitive volume. The minimum applied electric field needed for an optimized charge collection in the ionographic chamber is presented in terms of both the characteristic polarization time and the electret relaxation time. The maximum possible surface charge density in the latent image is calculated, first exhibiting direct proportionality with the polarizing voltage V0, and then following a V0 (1/2) dependence for voltages larger than the breakpoint voltage. The optimum exposure for latent image production is calculated. Exposures below this optimum give insufficient charge densities for subsequent development, while exposures above it degrade the image and eventually result in a uniform foil electret charged to its maximum theoretical value.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:issn
0094-2405
pubmed:author
pubmed:issnType
Print
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
137-44
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:articleTitle
Charging characteristics of ionographic latent images.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't