High-energy Electron Beam Irradiation Research Articles

Evolution of phases and microstructure in Fe81B13.5Si3.5C2 metallic glass during electron-beam and pulsed-laser irradiation.

A comparative study of electron-beam and pulsed-laser irradiation effects in metallic glasses has been performed in order to understand the relationship between magnetic behavior and select variations in the structural characteristics of alloy phases. Samples of ${\mathrm{Fe}}_{81}$${\mathrm{B}}_{13.5}$${\mathrm{Si}}_{3.5}$${\mathrm{C}}_{2}$ metallic glass were irradiated with a pulsed excimer laser (\ensuremath{\lambda}=308 nm, \ensuremath{\tau}=10 ns), with a high-energy electron beam (W=7 MeV), and with low-energy electron beams (W=30 and 50 keV). Irradiation-driven changes in the magnetic anisotropy and phase equilibrium of alloy samples were studied by M\"ossbauer spectroscopy and scanning electron microscopy. Complementary information was obtained using energy-dispersive x-ray analysis. High-energy electron-beam irradiation was found to induce an out-of-plane magnetic anisotropy due to changes in the chemical short-range order. Low-energy electron-beam irradiation resulted in the formation of crystalline regions, in which \ensuremath{\alpha}-Fe, Fe-Si, ${\mathrm{Fe}}_{3}$B, ${\mathrm{Fe}}_{2}$B, and clusters of \ensuremath{\gamma}-Fe were identified. Interpretation of these results is given in terms of radiation-enhanced diffusion. Pulsed-excimer-laser irradiation was found to induce controlled magnetic anisotropy without onset of bulk crystallization in the ${\mathrm{Fe}}_{81}$${\mathrm{B}}_{13.5}$${\mathrm{Si}}_{3.5}$${\mathrm{C}}_{2}$ amorphous system. The effect of excimer-laser-induced amorphization was evidenced in thermally annealed ${\mathrm{Fe}}_{81}$${\mathrm{B}}_{13.5}$${\mathrm{Si}}_{3.5}$${\mathrm{C}}_{2}$ samples and explained using melt model calculations. In all cases studied, the key to explaining the irradiation-induced property modifications is the underlying alloy microstructure.

Comparison of electron beam and pulsed laser irradiation effects in Fe80B20

The effects of high-energy electron beam and pulsed excimer laser irradiation on the magnetic properties of Fe80B20 amorphous alloy are investigated by means of transmission and conversion electron Mossbauer spectroscopy (CEMS) and scanning electron microscopy (SEM). Both types of irradiation were found to induce changes in the magnetic anisotropy of Fe80B20, but the influence of high-energy electron beam irradiation was weaker. Depending on the number of applied laser pulses and repetition rate, controlled magnetic anisotropy and/or relaxation of internal stresses could be obtained by excimer laser irradiation. The presence of molten zones subsequently solidified and of laser-induced internal stresses supports the model of closure domain structure.

High energy electron beam generation of oxidants for the treatment of benzene and toluene in the presence of radical scavengers

High energy electron beam irradiation of benzene and toluene in aqueous solution results in their destruction and the formation of highly oxidized reaction byproducts. The product distribution depends upon absorbed dose and pH and results from the reaction of benzene and toluene with the hydroxyl radical (OH .), followed by continued oxidation of intermediate by-products. The dose required to remove 99% ( D 0.99) of the benzene from solution, at an initial solute concentration of 17.0 μM (1.3 mg l −1), was 95 krad (0.95 kGy, [OH .] ≈ 2.7 × 10 −4 M). In the presence of a known radical scavenger, i.e. 3.3 mM methanol, a dose of 1510 krad ( 15.1 kGy, [OH .] ≈ 4.2 × 10 −3 M ) was required to achieve the same removal. Toluene showed greater removal, in the absence of methanol, than benzene under similar experimental conditions. The D 0.99 required to destroy an initial toluene concentration of 47.7 μM (4.4 mg l −1) was 165 krad (1.65 kGy, [OH .] ≈ 4.6 × 10 −4 M), whereas the D 0.99 for an initial toluene concentration of 16.4 μM (1.5 mg l −1), in the presence of 3.3 mM methanol, was 2074 krad (20.7 kGy, [OH .] ≈ 5.8 × 10 −3 M).

A Comparative Study of Pulsed Laser And Electron Beam Irradiation Effects In Fe81B13.5Si3.5C2 Glass

AbstractSamples of Fe81B13.5Si3.5C2 metallic glass were irradiated with a pulsed excimer laser (λ=308 nm, τ=10 ns), with a high-energy electron beam (W=7 MeV), and with low-energy electron beams (W=30 and 50 keV). Irradiation-driven changes in the magnetic anisotropy and phase equilibrium of alloy samples were studied by Mössbauer spectroscopy and scanning electron microscopy. Pulsed-excimer-laser irradiation was found to induce controlled magnetic anisotropy without onset of bulk crystallization in the Fe81B13.5Si3.5C2 amorphous system. High-energy electron-beam irradiation determined an out-of-plane magnetic anisotropy due to changes in the chemical short-range order. Low-energy electron-beam irradiation resulted in the formation of crystalline regions, in which α-Fe, Fe-Si, Fe3B, Fe2B, and clusters of γ-Fe were identified. Interpretation of these results is given in terms of radiation-enhanced diffusion.

A study on secondary defects in self-ion implanted Si

By using the cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering (and channeling) spectrometry (RBS) and high-energy electron beam irradiation technology with a high voltage electron microscope (HVEM), secondary defects in self-ion implanted Si has been studied. The result shows that the depths of secondary defect bands are related to the implantation energies, and the values of depths are slightly greater than the projected ranges of self-ions implanted into Si. In the higher energy region (>1 MeV), the former exceeds the latter by nearly 0.2-0.4 μm. Experiments indicate that the pre-implantation damage (the primary defect), on one hand, will superpose on the primary defects of post-implantations and make secondary defects increase, and on the other hand, it will also provide an enhanced-diffusion region for vacancies and interstitials created by the post-implantation and reduce the formation of secondary defects. Experiments also show that dislocation loops in secondary defect bands of self-implanted Si are interstitial in nature.

The Removal of Tri- (TCE) and Tetrachloroethylene (PCE) from Aqueous Solution using High Energy Electrons

Trichloroethylene (TCE) and tetrachloroethylene (PCE) are common groundwater contaminants that persist inithe environment. An innovative treatment process employing high energy electron beam irradiation has been shown to be an effective process for treating TCE- or PCE-contaminated water, wastewater, and water containing suspended solids. Experiments conducted at the Electron Beam Research Facility, Miami, Florida, have led to a better understanding of the factors that affect the removal efficiency of TCE and PCE in treated ground water (potable water), secondary wastewater effluent, and raw (untreated) wastewater. The effect of the addition of a hydroxyl radical scavenger, methanol, on the removal of TCE and PCE has also been determined. A quantitative description of TCE and PCE removal efficiency at several carbonate/bicarbonate ion concentrations, and in the presence of 3 percent clay, has also been developed. The reaction by-products have been characterized and chloride ion mass balance determined for...

Simulation calculation on electronic processes under intense X-ray and electron beam irradiation

Using cross section calculations for various atomic processes and simulation calculations for slowing down processes of photoinduced high-energy electrons, the spatial distribution of energy stored in an irradiated specimen is calculated. Typical calculations for Si targets which are important for synchrotron radiation research are shown. As an example of application, particular attention is paid to statistical mean values ( W-values) and their fluctuation (Fano-factors) of ionization yields for Ar atoms in liquid phase under high-energy electron-beam irradiation.

Treatment of Wastewater with High Energy Electron Beam Irradiation

The objective of this study was to determine the effectiveness of high energy electron beam irradiation in the disinfection of wastewater, and removal of organic matter through measurement of BOD and COD values. The raw wastewater and secondary effluents were transported in a 22.7m3 tank truck to the research facility built at the Virginia Key Wastewater Treatment Plant, Miami, Florida. The facility is equipped with a 1.5 MeV, 50 ma electron accelerator capable of treating the wastewater at a volumetric flow rate of 7.57 l/sec. Some preliminary disinfection was also carried out using a 60Co gamma radiation source. Removal of coliphage, total coliforms, and standard plate counts was found on the order of two to three orders of magnitude in raw wastewater. Gamma irradiation gave slightly better inactivation. However, in all cases it was found that coliphage is more resistant than the other two organisms investigated. Twenty to 30 percent removal of BOD was observed in the case of raw wastewater, however, no significant change was observed in removal of COD.

High Energy Electron Beam Irradiation: An Advanced Oxidation Process for the Treatment of Aqueous Based Organic Hazardous Wastes

Abstract Advanced oxidation processes for the removal and destruction of hazardous organic chemicals in water and wastewater is a research area of increasing interest. Advanced oxidation processes generally consider the hydroxyl radical, OH-, the major reactive transient species. A novel process under development, utilizing high energy electrons, extends this concept to include the simultaneous formation of approximately equal concentrations of oxidizing and reducing species. Irradiation of aqueous solutions results in the formation of the aqueous electron, e−aq, hydrogen atoms, H-, and OH-. These reactive transient species initiate chemical reactions capable of destroying organic compounds in aqueous solution. This paper presents data on the removal of six common organic contaminants that have been studied at the Electron Beam Research Facility. The removal and the factors affecting removal were determined. This study focuses on halogenated ethenes, benzene and substituted benzenes. Removal is described in waters of different quality, including potable water, and raw and secondary wastewater. Removal efficiencies ranged from 85 to >99% and varied with water quality, solute concentration, dose and compound.

High energy electron beam irradiation: An innovative process for the treatment of aqueous based organic hazardous wastes

Abstract The use of high energy electrons for the treatment of aqueous solutions appears to be a promising approach in solving the numerous problems associated with contaminated water. Irradiation of aqueous solutions results in the formation of reactive transient species, e– aq, H•, and HO•. In aqueous solutions of toxic and hazardous chemicals, the transient species react with the contaminants resulting in their removal from solution. The study reported in this paper utilizes a pilot plant capable of treating 120 gpm. The accelerating voltage of the electron accelerator is 1.5 MeV with variable current of up to 50 mA. Influent streams of potable water, and raw and secondary wastewater have been used for this study. The compounds studied include halogenated methanes, ethanes, ethenes, benzene and substituted benzenes. Removal efficiencies range from 85 to greater than 99%.

Retardation and Enhancement in Lateral Solid Phase Epitaxy of Si on SiO2 by MeV Electron Beam Irradiation

ABSTRACTWe have demonstrated the high energy (MeV) electron beam irradiation effects on lateral solid phase epitaxy (L-SPE) of Si-on-insulator (SOI). Thinned samples were set on a hot stage in a 2 MeV electron microscope and L-SPE growth under 2 MeV electron irradiation conditions was monitored in-situ by using the same microscope. L-SPE growth rate for the irradiation dose of 1021 cm−2 was enhanced by about 1.5 times greater than that under unirradiated condition. For electron beam irradiation doses higher than about 1023 cm−2, L-SPE growth was suppressed. Displacement of Si atoms, contamination effect and ionization effect are discussed as causes for the growth rate retardation and enhancement of L-SPE by electron beam irradiation.

Irradiated cross-linked wire

Generally speaking, polyurethane has excellent mechanical properties but poor water resistance. It is rather difficult to obtain flame retardant polyurethane while maintaining water resistance. We ascertained that improvement in water resistance could be achieved on polyurethane by high energy electron beam irradiation. The irradiated cross-linked polyurethane is very useful as jacketing material for automobile cables.

Formation of A GexSi1-x alloy layer by high-energy electron-beam irradiation

A heteroepitaxial GexSi1-x (x = 0.14) alloy layer was formed by pulsed 7 MeV electron-beam irradiation at room temperature. A Ge film 3000 Å thick was vacuum evaporated onto Si(111). After irradiation by a fluence of (3.0–5.0)×1018 electrons cm-2 at room temperature (40 or 60°C), the formation of the epilayer was confirmed from (111) X-ray diffraction measurements and Rutherford backscattering spectrometry. The irradiation introduced many Frenkel pairs into the sample, and these defects enhanced the diffusion at the interface.

高エネルギー電子ビームによる相互拡散

高エネルギー電子ビームによる相互拡散

Electron beam radiation effects on NiO crystals

It is well known that various electron beam induced effects can occur under high energy electron beam irradiation on the studied material in an electron microscope. It has been reported that under electron beam irradiation small metallic Ni particles can be reduced from the bulk NiO crystals and these Ni crystals are always in epitaxial relationship with the NiO substrate. These Ni particles may be formed by the preferential knock-out of oxygen atoms by the incident electrons and the subsequent aggregation of Ni atoms to form the nucleii. These nuclei will grow with further electron beam irradiation, forming the small Ni islands on the surface of the NiO crystals. Recently, we observed that not only does the reduction process occur on the NiO surface but also other kinds of interactions occur at the same time. First, large NiO crystals can be melted and flow away from the radiated area in an electron microscope. The process is radiation dose dependent.

Sintering under a high-power electron beam

The influence of high-energy electron beam irradiation (1.6 MeV) on the sintering of chemically pure europium oxide Eu 2O 3 and hexagonal boron nitride BN has been evaluated. Eu 2O 3 sintering is noticeably activated and effects changes in the process kinetics. Introduction of TiO 2 as a dopant (0.1–1.0 mass %) greatly activates the process of sintering. The hexagonal boron nitride does not sinter under high-energy electron beam irradiation but dissociates and forms molten boron at high temperature.

Electron-beam-initiated destruction of low concentrations of vinyl chloride in carrier gases

The destruction of ppm levels of vinyl chloride by high-energy electron-beam irradiation has been investigated in various host gases. Measurements of vinyl chloride destruction have been determined over the electron-beam dose range ∼0.01–6 Mrad. The low dose results indicate G values in the range 9–13 are obtained, depending upon the host gas. The high dose results indicate that a factor of 20 reduction in vinyl chloride concentration can be realized for an initial 10 ppm molar vinyl chloride stream in air. A discussion of the kinetic processes responsible for vinyl chloride destruction is presented.

Plasticized Polyvinyl Chloride Finishes for Durable Flame Retardancy for Cotton Fabrics

Abstract Cotton flannels were padded with flame retardant compositions comprising a vinyl chloride co-polymer resin, a halogenated phosphate ester plasticizer and a small amount of an unsaturated alkyl dimethacrylate monomer to give varying add-on's-up to 60% by weight of the cottons. The padded cotton flannels were then exposed to high energy electron beam irradiation dosages in the presence of air at ambient temperatures. Limiting Oxygen Index (LOI) measurements are reported for the treated cottons for increasing numbers of laundering cycles and correlated with fabric weight changes. Analogous experiments were carried out with the same flame retardant composition padded onto the cotton flannels to similar add-on's but with the resultant samples not subjected to electron beam irradiation. The laundering durability of the irradiated treated cotton flannels was significantly superior and weight losses were lower, especially after extended launderings. Irradiation treatments offer a potentially attractive a...

Assay of urease activity using 14C-urea in stored, geologically preserved, and in irradiated soils

Soils from adverse and diverse climatic and geographic areas, and stored for various lengths of time, were examined for their urease activities. During a period of 26 months of air-dry storage of Hawaiian and Puerto Rico latosols, one soil showed an increase in activity to 108·5 per cent and others a decrease to as little as 36 per cent. Urease activity found in 6–12 years stored, air-dry agricultural soils correlated with the organic matter content rather than with the numbers of microorganisms. In samples from the 60-years-old Hilgard soil collection, urease activity reflected both the organic carbon content and the numbers of organisms present. Measurable urease activities were detected in 8715 and 9550-years-old, radiocarbon dated, Alaska permafrost samples. No activity was detected in a 32,000-years-old sample. No urease activity was present in two high-salinity soils. Urease activity was detected in an alkali soil and in an acid soil, but highest activity was usually found in neutral soils. A high-energy electron-beam irradiation dosage of 4 Mrad increased urease activity in some soils, but decreased activity in two others. Doses of 8 Mrad decreased urease activity below their native levels in all soils. Evidently, an intracellular urease component becomes more accessible to substrate upon death of organisms. This effect is observable because of the strong resistance of soil urease to radiation inactivation. Urea-amended Dublin soil, subjected to incubation at 80 per cent relative humidity showed a measurable urease activity. It appears that an extracellular component of soil urease becomes associated with inorganic and organic soil colloidal particles and retains its activity for extended periods of time. A new method for urease activity determination in soils was devised, based on the detection of 14CO 2 release from 14C-urea-amended soils.

Electron-Beam Therapy in the Management of Carcinoma of the Breast

Breast cancer, its metastases to regional lymph nodes, and chest-wall recurrences are frequent problems which require skillful management. While these lesions are moderately superficial, skin reaction or damage to underlying tissues, particularly to bone and lung, is often the factor limiting the delivery of adequate tumor doses by conventional radiation therapy. Lymph-node metastases or chest-wall recurrences may develop in previously irradiated areas, and the skin changes prevent further treatment by the usual technics. In these circumstances, electron-beam therapy appears to us to offer definite advantages over conventional treatment. The purpose of this paper is to present our preliminary observations in treating 70 patients with cancer of the breast by means of the high-energy electron beam produced by the betatron at Memorial Center (New York). The following considerations entered into our decision to explore the role of high-energy electron-beam irradiation. (1) The electron beam has a sharp fall-off which provides sparing of underlying tissues such as the lung. (2) The depth of penetration may be regulated by varying the energy of the electron beam. Figure 1 shows the central axis depth-dose distributions produced by electron beams of various energies. Roughly, for every increase of 2 Mev energy, the effective range of radiation increases by approximately 1 cm. Thus, for treating superficial lesions less than 3 cm. deep, 10.4 Mev energy may be chosen. This will give a high radiation dose to the first 3 cm. of tissue and very little radiation to the tissue beyond. On the other hand, when a lesion is slightly deeper or thicker, a higher energy range, i.e., 18 to 22.5 Mev, may be selected for irradiation. The 4 to 5 cm. of tissue adjacent to the skin surface will receive effective radiation while underlying tissues will receive considerably less. (3) The maximum dose occurs at approximately 10 to 15 mm. below the skin surface (Fig. 1), effectively reducing skin dose. (4) The radiation throughout the tumor is homogeneous. (5) There is little or no differential bone absorption. (6) Since the total volume of tissue irradiated is reduced, systemic reactions may also be expected to be lessened. This is of importance because many of the patients with advanced cancer of the breast are in poor physical condition. It is worthwhile to achieve effective local palliation with the minimum systemic reaction possible. From January 1955 to December 1958, 70 patients with breast cancer in various stages were accepted for electron-beam therapy. Of these 70 patients, 18 were treated for inoperable carcinoma, 38 received treatment for chest-wall recurrences or for lymph-node metastases following surgery, irradiation, or both, and 14 were given postoperative irradiation following radical mastectomy or local excision of the tumor.