Radiation‐Induced Electrical Conductance in the Liquids Argon, Neopentane, and n‐Hexane: The Influence of Electron Localization Efficiency on the Free‐Ion Yield

1969 ◽  
Vol 51 (4) ◽  
pp. 1276-1279 ◽  
Author(s):  
P. H. Tewari ◽  
G. R. Freeman
Keyword(s):  
Electrical Conductance ◽  
Electron Localization ◽  
Free Ion ◽  
Radiation Induced

The effect of pressure on the radiation-induced conductance of liquid hydrocarbons

1969 ◽  
Vol 47 (6) ◽  
pp. 885-892 ◽  
Author(s):  
D. W. Brazier ◽  
G. R. Freeman
Keyword(s):  
Solid Phase ◽  
The Other ◽  
Electron Localization ◽  
Cavity Model ◽  
Liquid Hydrocarbons ◽  
Appreciable Increase ◽  
Free Ion ◽  
Radiation Induced ◽  
Phase Glass ◽  
Ion Yields

An attempt was made to test the cavity model of electron localization in liquid hydrocarbons by measuring the effect of pressures up to 4000 bars on the radiation induced conductance of n-pentane, n-hexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane at 30°. Measurements at 3 and 56° were also made on n-hexane and n-octane. The relative induced conductance, i.e. the ratio of the induced conductance at pressure p to that at 1 bar, decreased with increasing pressure. The amount of decrease was slightly greater at low than at high temperatures. The behavior of 2,2-dimethylbutane was complex and is not understood. For the other liquids, it was concluded that the free ion yields remained constant or decreased somewhat with increasing pressure. An appreciable increase in the free ion yields, which is a possible implication of the cavity model of electron localization, did not occur. Therefore, either (a) the cavity model of electron localization in hydrocarbons is wrong, or (b) application of pressures up to 4000 bars did not appreciably alter the cavity concentrations in the liquids. Perhaps the cavity concentration is greatly reduced only by pressures great enough to cause a solid phase (glass or crystal) to form.

On the correlation between electron mobility, free-ion yield, and electron thermalization distance in nonpolar dielectric liquids

1993 ◽  
Vol 71 (3) ◽  
pp. 287-293 ◽  
Author(s):  
Jean-Paul Jay-Gerin ◽  
Thomas Goulet ◽  
Isabelle Billard
Keyword(s):  
Electron Mobility ◽  
Point Of View ◽  
Thermal Electron ◽  
Polar Dielectric ◽  
Dielectric Liquids ◽  
Free Ion ◽  
Radiation Induced ◽  
Ionization Detectors ◽  
Nonpolar Dielectric ◽  
Liquid Ionization

The correlation between the thermal electron mobility, μe, the radiation-induced free-ion yield Gfi at zero applied electric field, and the most probable thermalization distance b of secondary electrons, is examined for 52 different pure non-polar dielectric liquids for which data have been reported in the literature. It is shown that, in liquids for which μe > 10−1 cm2 V−1 s−1, the variation of Gfi with μe is well represented by a relation of the type [Formula: see text] where n ≈ 0.31. The connection between Gfi and μe can be described through the product εsb, where εs is the static dielectric constant of the intervening liquid. In particular, 1/εsb is shown to correlate with both μe and Gfi. Analysis of these correlations allows us to estimate an upper limit of μe that can be attained in a room-temperature dielectric liquid, information of utmost importance from the point of view of application to liquid ionization detectors.

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Radiation-induced surface decomposition

1983 ◽  
Vol 41 ◽  
pp. 368-369
Author(s):  
M. L. Knotek
Keyword(s):  
Ionizing Radiation ◽  
Atomic Structure ◽  
Chemical Bonding ◽  
Neutral Species ◽  
Radiation Induced ◽  
Physical And Chemical ◽  
Surface Decomposition ◽  
The Relationship ◽  
Electron And Photon ◽  
Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

Xenon ion irradiation of superconducting YBa2Cu3O7 thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 92-93
Author(s):  
H. Watanabe ◽  
B. Kabius ◽  
B. Roas ◽  
K. Urban
Keyword(s):  
Defect Formation ◽  
Ion Irradiation ◽  
High Resolution Electron Microscopy ◽  
Structural Disorder ◽  
Flux Lines ◽  
Pinning Effect ◽  
Magnetic Flux Lines ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Induced Defects

Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

Ultrastructural Immunocytochemistry of Five Rat Pituitary Adenomas

1980 ◽  
Vol 38 ◽  
pp. 724-725
Author(s):  
D. J. McComb ◽  
N. Ryan ◽  
E. Horvath ◽  
K. Kovacs ◽  
E. Nagy ◽  
...  
Keyword(s):  
Pituitary Adenomas ◽  
Pituitary Tumors ◽  
Electron Microscopic ◽  
Electron Microscopic Immunocytochemistry ◽  
Transmission Electron ◽  
Rat Pituitary ◽  
Radiation Induced ◽  
Group 5 ◽  
Group 2 ◽  
Microscopic Techniques

Conventional light and electron microscopic techniques failed to clarify the cellular composition and derivation of spontaneous and induced, intrasellar and transplanted pituitary adenomas in rats (1). In the present work, electron microscopic immunocytochemistry was applied to evaluate five adenohypo-physial tumors using a technique described by Moriarty and Garner (2). Spontaneously occurring pituitary adenomas (group 1) were harvested from aging female Long-Evans rats. R-Amsterdam rats were treated with 2 x 1.0 mg estrone acetate (HogivaI) s.c. weekly for 6 months. Pituitary adenomas in excess of 30 mg were removed from these animals to make up the tumors of group 2. Groups 3 and 4 consisted of estrogen-induced autonomous transplan¬ted pituitary tumors MtT.WlO and MtT.F4. Group 5 was a radiation-induced transplanted autonomous pituitary tumor MtT.W5. The tumors of groups 3,4 and 5 were allowed to proliferate in host rats 6-8 weeks prior to removal for processing. Tissue was processed for transmission electron microscopy (glutaraldehyde fixation, OsO4 postfixation and epoxy resin embedding), and electron microscopic immunocytochemistry (3% paraformaldehyde fixation and Araldite embedding).

Radiation-Induced Precipitation in Ti-6A1-4V

1980 ◽  
Vol 38 ◽  
pp. 154-155
Author(s):  
J. E. O'Neal ◽  
S. M. L. Sastry ◽  
J. W. Davis
Keyword(s):  
Dark Field ◽  
Dislocation Loops ◽  
Beta Titanium Alloy ◽  
Defect Clusters ◽  
Weak Beam ◽  
Beta Titanium ◽  
Small Defect ◽  
Radiation Induced ◽  
Vector Orientation ◽  
Defect Microstructures

The radiation-induced defect structure and nonequilibrium phase precipitation were studied in T1-6A1-4V (an alpha-beta titanium alloy), irradiated at 450 ± 30°C in row VII of the EBR-II to a fluence of 3.0 × 1021 neutrons/cm2 (En > 0.1 MeV). The Irradiation-induced defect microstructures were examined using bright-field, conventional dark-field, and weak-beam dark-field techniques. The nature of dislocations and dislocation loops was determined by standard-contrast experiments under two-beam conditions, and the small defect clusters were identified using the line-of-contrast criterion and black-white vector orientation criterion.

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