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Sample records for 1-mev electron irradiation

  1. ELECTRON IRRADIATION OF SOLIDS

    DOEpatents

    Damask, A.C.

    1959-11-01

    A method is presented for altering physical properties of certain solids, such as enhancing the usefulness of solids, in which atomic interchange occurs through a vacancy mechanism, electron irradiation, and temperature control. In a centain class of metals, alloys, and semiconductors, diffusion or displacement of atoms occurs through a vacancy mechanism, i.e., an atom can only move when there exists a vacant atomic or lattice site in an adjacent position. In the process of the invention highenergy electron irradiation produces additional vacancies in a solid over those normally occurring at a given temperature and allows diffusion of the component atoms of the solid to proceed at temperatures at which it would not occur under thermal means alone in any reasonable length of time. The invention offers a precise way to increase the number of vacancies and thereby, to a controlled degree, change the physical properties of some materials, such as resistivity or hardness.

  2. Electron Beam Materials Irradiators

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.

    2012-06-01

    Radiation processing is a well established method for enhancing the properties of materials and commercial products by treating them with ionizing energy in the form of high-energy electrons, X-rays, and gamma rays. Beneficial effects include polymerizing, cross-linking, grafting and degrading plastics, sterilizing single-use medical devices, disinfecting and disinfesting fresh foods, purifying drinking water, treating wastewater and other toxic waste materials that harm the environment, and many other applications that are still being evaluated. Industrial electron accelerators of several types have been developed and are being used for these applications. More than 1800 electron accelerators are presently installed in facilities worldwide for these purposes.

  3. Electron Irradiation Damage in Quartz

    NASA Astrophysics Data System (ADS)

    Ayensu, Akwasi; Ocran, John

    2002-03-01

    Transmission electron microscopy for observing highly beam sensitive materials had been used to study the microstructure of deformed quartz crystals. At 100 kV accelerating voltage and electron flux of 3 x 10^8 e/cm2/s, beam spots damage appeared within five minutes of exposure to the electron beam. The rate of damage was found to depend on the crystal type; in particular, on the OH content and initial defect density, since these factors controlled the plasticity of quartz. The electron irradiation damage was manifested as black spots, prismatic dislocation loops, defect clusters, hairpin shaped images of dislocations and long segements of dislocation loops. The observed microstructure indicate that during electron beam irradiation, the primary defects in quartz attained sufficiently high mobilities permitting large-scale recombination and clustering leading to rapid creation of secondary defects from the clustering processes. The number of electrons that are lost by the recombination process is determined by the density of the recombination centres and the probability that an electron will interact with the centre.

  4. Electron spin resonance identification of irradiated fruits

    NASA Astrophysics Data System (ADS)

    Raffi, Jacques J.; Agnel, Jean-Pierre L.

    The electron spin resonance spectrum of achenes, pips, stalks and stones from irradiated fruits (strawberry, raspberry, red currant, bilberry, apple, pear, fig, french prune, kiwi, water-melon and cherry) always displays, just after γ-treatment, a weak triplet ( aH≈30 G) due to a cellulose radical; its left line (lower field) can be used as an identification test of irradiation, at least for strawberries, rapsberries, red currants or bilberries irradiated in order to improve their storage time.

  5. Structural change of graphite during electron irradiation

    SciTech Connect

    Koike, J. . Dept. of Mechanical Engineering); Pedraza, D.F. )

    1992-01-01

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. Results consistently indicated absence of long-range order periodicity in the basal plane, and loose retention of the c-axis periodicity. Structure was modeled based on a mixture of sixfold and non-sixfold atom rings. Formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.

  6. Structural change of graphite during electron irradiation

    SciTech Connect

    Koike, J.; Pedraza, D.F.

    1992-12-31

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. Results consistently indicated absence of long-range order periodicity in the basal plane, and loose retention of the c-axis periodicity. Structure was modeled based on a mixture of sixfold and non-sixfold atom rings. Formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.

  7. Electron irradiation of dry food products

    NASA Astrophysics Data System (ADS)

    Grünewald, Th.

    The interest of the industrial food producer is increasing in having the irradiation facility installed in the food processing chain. The throughput of the irradiator should be high and the residence time of the product in the facility should be short. These conditions can be accomplished by electron irradiators. To clarify the irradiation conditions spices taken out of the industrial process, food grade salt, sugar, and gums as models of dry food products were irradiated. With a radiation dose of 10 kGy microbial load can be reduced on 10∗∗4 microorganisms/g. The sensory properties of the spices were not changed in an atypical way. For food grade salt and sugar changes of colour were observed which are due to lattice defects or initiated browning. The irradiation of several gums led only in some cases to an improvement of the thickness properties in the application below 50°C, in most cases the thickness effect was reduced. The products were packaged before irradiation. But it would be possible also to irradiate the products without packaging moving the product through the iradiation field in a closed conveyor system.

  8. Electron irradiation of modern solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.

    1977-01-01

    A number of modern solar cell types representing 1976 technology (as well as some older types) were irradiated with 1 MeV electrons (and a limited number with 2 MeV electrons and 10 MeV protons). After irradiation, the cells were annealed, with I-V curves measured under AMO at 30 C. The purpose was to provide data to be incorporated in the revision of the solar cell radiation handbook. Cell resistivities ranged from 2 to 20 ohm-cm, and cell thickness from 0.05 to 0.46 mm. Cell types examined were conventional, shallow junction, back surface field (BSF), textured, and textured with BSF.

  9. Electron irradiation of N type cadmium telluride

    NASA Astrophysics Data System (ADS)

    Bauer, C. P., Jr.

    1985-03-01

    An experiment is described in which 30 MeV electrons were used to irradiate a sample of cadmium telluride. A brief history of irradiation studies of cadmium telluride is given, followed by the description of the construction of a laboratory used in the taking of Hall measurements and resistivity versus temperature data. The irradiation was performed at the Naval Postgraduate School linear accelerator facility and damage was observed in the CdTe sample at doses above 10 to the 13th power electrons/sq cm. The sample was held at 100 K for the irradiation. Three results were noted from the Hall and resistivity data. First, the resistivity increased by a factor of two at radiation doses of 10 to the 15th power electrons/sq cm. Secondly, there was a 10% lowering of the electron mobility at 77 K. Finally, possible annealing was seen at 160 K for the 10 to the 13th power electrons/sq cm dose resistivity versus temperature graph. Photoluminescence measurements confirmed the existence of damage by an increase of a broad maximum associated with defects.

  10. Electron Irradiation of Interstellar Ice Analogues

    NASA Astrophysics Data System (ADS)

    Nair, B. G.; Mason, N. J.

    2011-05-01

    Molecular synthesis in the Universe primarily occurs in the icy mantles on dust grains in dense interstellar dust clouds. The interaction of photons, electrons and cosmic rays with these ice mantles triggers complex chemical synthesis leading to the formation of complex molecules. Such molecular reactions can only be understood by systematic laboratory studies. In our experiments astrophysical environments are recreated in the laboratory using an ultra high vacuum chamber (UHV) capable of reaching pressures of the order of 10 -10 mBar containing a liquid helium cryostat capable of attaining a temperature of 20 K. Ice films are deposited on a ZnSe substrate (cooled by cryostat) by background deposition and irradiated with electrons of 1KeV energy. Chemical changes induced by electron irradiation were monitored by an infrared spectrometer. By varying the temperature, we also investigate the temperature dependence on the kinetics of the reactions. In this poster we will present the first results of electron irradiation of simple organic molecules like formamide (HCONH2) and allyl alcohol (CH2CHCH2OH).

  11. Electron irradiation of tandem junction solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.; Scott-Monck, J. A.

    1979-01-01

    The electrical behavior of 100 micron thick tandem junction solar cells manufactured by Texas Instruments was studied as a function of 1 MeV electron fluence, photon irradiation, and 60 C annealing. These cells are found to degrade rapidly with radiation, the most serious loss occurring in the blue end of the cell's spectral response. No photon degradation was found to occur, but the cells did anneal a small amount at 60 C.

  12. [Dosimetry of total skin electron irradiation

    PubMed

    Kontra, Gábor; Horváth, Akos; Bajcsay, András; Németh, György

    2000-07-01

    Elaboration of such a simple technique for total skin electron irradiation which ensures good dose homogeneity and minimal x-ray background dose. MATERIALS AND METHODS: We started large electron field irradiations with the Neptun 10p linear accelerator in the National Institute of Oncology -Budapest in 1986. After the installation of the Siemens Mevatron KD linear accelerator it was possible to introduce the modified Stanford technique. This technique satisfies better the requirements given in the objective. The required field size of 200x75 cm is produced as a result of two fields with 30 degrees angular separation (dual field) at a source skin distance of 465 cm. The patient's body is exposed to six dual electron fields. The electron energy is 6 MeV. Despite the long source skin distance the treatment time is relatively short due to the high dose rate (940 mu/min) capability of our Mevatron KD. The in air dose profiles were measured in miniphantom with semiconductor detector. Depth dose curves were measured in water and in polystyrene phantom with semiconductor detector and with films. RESULTS: The measured dose homogeneity of the 6 MeV energy dual field with 30 degrees angular separation is within +/- 5%in a 200x75cm plane field. The depth of dose maximum of the resulting dose distribution of six dual field irradiation is between 2 mm and 5 mm, while the depth of 80% isodose curve is about 8 mm. The total body x-ray background dose is less than 1% of the skin dose. CONCLUSION: The modified Stanford technique adapted to our Mevatron KD linear accelerator is suitable for total skin electron beam therapy. PMID:12050758

  13. Impact of electron irradiation on electron holographic potentiometry

    SciTech Connect

    Park, J. B.; Niermann, T.; Lehmann, M.; Berger, D.; Knauer, A.; Weyers, M.; Koslow, I.; Kneissl, M.

    2014-09-01

    While electron holography in the transmission electron microscope offers the possibility to measure maps of the electrostatic potential of semiconductors down to nanometer dimensions, these measurements are known to underestimate the absolute value of the potential, especially in GaN. We have varied the dose rates of electron irradiation over several orders of magnitude and observed strong variations of the holographically detected voltages. Overall, the results indicate that the electron beam generates electrical currents within the specimens primarily by the photovoltaic effect and due to secondary electron emission. These currents have to be considered for a quantitative interpretation of electron holographic measurements, as their negligence contributes to large parts in the observed discrepancy between the measured and expected potential values in GaN.

  14. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    NASA Astrophysics Data System (ADS)

    Bakar, Khomsaton Abu; Ahmad, Pauzi; Zulkafli, Hashim, Siti A'aisah

    2014-09-01

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  15. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    SciTech Connect

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A'aisah; Ahmad, Pauzi

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  16. WEBEXPIR: Windowless target electron beam experimental irradiation

    NASA Astrophysics Data System (ADS)

    Dierckx, Marc; Schuurmans, Paul; Heyse, Jan; Rosseel, Kris; Van Tichelen, Katrien; Nactergal, Benoit; Vandeplassche, Dirk; Aoust, Thierry; Abs, Michel; Guertin, Arnaud; Buhour, Jean-Michel; Cadiou, Arnaud; Abderrahim, Hamid Aït

    2008-06-01

    The windowless target electron beam experimental irradiation (WEBEXPIR) program was set-up as part of the MYRRHA/XT-ADS R&D effort on the spallation target design to investigate the interaction of a proton beam with a liquid lead-bismuth eutectic (LBE) free surface. In particular, possible free surface distortion or shockwave effects in nominal conditions and during sudden beam on/off transient situations, as well as possible enhanced evaporation were assessed. An experiment was conceived at the IBA TT-1000 Rhodotron, where a 7 MeV electron beam was used to simulate the high power deposition at the MYRRHA/XT-ADS LBE free surface. The geometry and the LBE flow characteristics in the WEBEXPIR set-up were made as representative as possible of the actual situation in the MYRRHA/XT-ADS spallation target. Irradiation experiments were carried out at beam currents of up to 10 mA, corresponding to 40 times the nominal beam current necessary to reproduce the MYRRHA/XT-ADS conditions. Preliminary analyses show that the WEBEXPIR free surface flow was not disturbed by the interaction with the electron beam and that vacuum conditions stayed well within the design specifications.

  17. Total skin electron irradiation techniques: a review

    PubMed Central

    Milecki, Piotr; Skórska, Małgorzata; Fundowicz, Dorota

    2013-01-01

    Total skin electron irradiation (TSEI) has been employed as one of the methods of mycosis fungoides treatment since the mid-twentieth century. In order to improve the effects and limit the complications following radiotherapy, a number of varieties of the TSEI method, frequently differing in the implementation mode have been developed. The paper provides a systematic review of the different varieties of TSEI. The discussed differences concerned especially: (i) technological requirements and geometric conditions, (ii) the alignment of the patient, (iii) the number of treatment fields, and (iv) dose fractionation scheme. PMID:24278046

  18. Effect of Electron Beam Irradiation on Tensile Strength of Polypropylene

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroshi; Ikeda, Masayuki; Shimbo, Minoru; Miyano, Yasushi

    In this paper, the effects of the intensity of electron beam and the variation with time after irradiation of electron beam on the tensile strength of the polypropylene (PP), which is widely used as medicine containers, were investigated. PP with and without colorants were used first and samples irradiated under various intensity of EB. A tensile test on the irradiated samples with elapsed time after the irradiation of the electron beam was carried out. The effects of those factors on the tensile strength were discussed. The following results were obtained (1) The tensile strength of PP decreased due to the influence of the electron beam irradiation, however the rate of the decrease in strength was small compared with the original one. Furthermore, the rate of the decrease in strength was very small owing to the variation with time after the EB irradiation. (2) The tensile rupture strength of PP increased and the rupture strain owing to the influence of the electron beam irradiation compared with the original one. In addition, these rupture strength increased and the rupture strain decreased along with time after the irradiation of the electron beam. (3) The tensile rupture strain energy of PP decreased owing to the influence of the electron beam irradiation compared with the original one. In addition, the strain energy decreases with time after the irradiation of the electron beam. Moreover, the strength characteristics of PP with colorants received greater influence of electron beam compared with the one without colorants.

  19. Microstructural change on electron irradiated oxide dispersion strengthened ferritic steels

    NASA Astrophysics Data System (ADS)

    Kinoshita, H.; Akasaka, N.; Takahashi, H.; Shibahara, I.; Onose, S.

    1992-09-01

    Oxide dispersion strengthened (ODS) ferritic steels were irradiated in a high voltage electron microscope (HVEM) to study their response to irradiation. Fe-13Cr with 0.25 wt% Y2O3 as dispersed particles and containing additions of either 0.45% Nb, 0.45% V and 0.67% Zr were irradiated at 673 and 723 K up to 15 dpa. The Y2O3 particles in all specimens were stable under these irradiation conditions. During irradiation, two types of dislocations were formed but observable voids were not formed. Furthermore, plate-like and granular-like precipitates formed in both the irradiated and nonirradiated regions.

  20. Instability of nanoscale metallic particles under electron irradiation in TEM

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Zhang, S. G.; Xia, M. X.; Li, J. G.

    2016-03-01

    The stability of nano metallic glass under electron beam in transmission electron microscope (TEM) was investigated. The most common voltage of TEM used in metallic materials characterization was either 200 kV or 300 kV. Both situations were investigated in this work. An amorphous metallic particle with a dimension of a few hundred nanometers was tested under 300 keV electron irradiation. New phase decomposed from the parent phase was observed. Moreover, a crystal particle with the same composition and dimension was tested under 200 keV irradiation. Decomposition process also occurred in this situation. Besides, crystal orientation modification was observed during irradiation. These results proved that the electron beam in TEM have an effect on the stability of nanoscale samples during long time irradiation. Atomic displacement was induced and diffusion was enhanced by electron irradiation. Thus, artifacts would be induced when a nanoscale metallic sample was characterized in TEM.

  1. Synthesis of silver nanoparticles by electron irradiation of silver acetate

    NASA Astrophysics Data System (ADS)

    Li, Yue; Kim, Yong Nam; Lee, Eun Je; Cai, Wei Ping; Cho, Sung Oh

    2006-10-01

    A novel and facile route to synthesize crystalline silver nanoparticles is presented, which is based on electron irradiation technique. Only by irradiating an electron beam onto silver acetate precursor material, silver nanocrystals with the sizes of 15-40 nm were synthesized. The morphology and chemical composition of the irradiated samples were characterized by SEM, TEM, XRD and EELS. The precursor material was decomposed by the energetic electrons and consequently the chemical composition of the material was changed. As the electron fluence was gradually increased, the precursor was converted to silver (I) oxide and finally into silver nanocrystals. Thus, besides silver nanoparticles, silver oxide film can also be synthesized using the electron irradiation technique by controlling the electron fluence. The technique can be useful for mass production of silver nanoparticles and for patterned silver nanoparticle film.

  2. Electron beam irradiation effects in Trombay nuclear waste glass

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Kadam, R. M.; Mishra, R. K.; Dutta, D.; Pujari, P. K.; Kaushik, C. P.; Kshirsagar, R. J.; Tomar, B. S.; Godbole, S. V.

    2011-10-01

    Spectroscopic investigations were carried out on electron beam irradiated sodium barium borosilicate glasses, which is the base glass for immobilization of nuclear high level radioactive waste, generated from the research reactors at Bhabha Atomic Research Centre, Trombay. This was done in order to access the defects generated in it under long term irradiation. Electron paramagnetic resonance was used to identify the defect centers generated in the borosilicate glass after irradiation. In addition, positron annihilation spectroscopy and infrared investigations were done on the samples to evaluate the radiation induced changes in the glass. It was found that, boron-oxygen and silicon based hole centers along with E' centers are getting formed in the glass after irradiation due to the breaking of the Si sbnd O bonds at regular tetrahedron sites of Si sbnd O sbnd Si. The positron annihilation spectroscopy data gave an idea regarding the free volume size and fraction of the glasses before and after irradiation. It was seen that, after irradiation the free volume size in the glass increased with creation of additional sites. Microwave power variation and temperature variation studies suggested the formation of at least five different radicals in the irradiated glasses. The spin Hamiltonian parameter of all the radical species were determined by computer simulation. An electron paramagnetic resonance spin counting technique was employed to evaluate the defect concentration in the glasses after irradiation.

  3. In situ formation of bismuth nanoparticles through electron-beam irradiation in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Sepulveda-Guzman, S.; Elizondo-Villarreal, N.; Ferrer, D.; Torres-Castro, A.; Gao, X.; Zhou, J. P.; Jose-Yacaman, M.

    2007-08-01

    In this work, bismuth nanoparticles were synthesized when a precursor, sodium bismuthate, was exposed to an electron beam at room temperature in a transmission electron microscope (TEM). The irradiation effects were investigated in situ using selected-area electron diffraction, high-resolution transmission electron microscopy and x-ray energy dispersive spectroscopy. After the electron irradiation, bismuth nanoparticles with a rhombohedral structure and diameter of 6 nm were observed. The average particle size increased with the irradiation time. The electron-induced reduction is attributed to the desorption of oxygen ions. This method offers a one-step route to synthesize bismuth nanoparticles using electron irradiation, and the particle size can be controlled by the irradiation time.

  4. Impact of electron beam irradiation on fish gelatin film properties.

    PubMed

    Benbettaïeb, Nasreddine; Karbowiak, Thomas; Brachais, Claire-Hélène; Debeaufort, Frédéric

    2016-03-15

    The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino acids. No modification of the crystallinity of the film is observed. These findings suggest that if structure changes, it only occurs in the amorphous phase of the gelatin matrix. It is also observed that irradiation enhances the thermal stability of the gelatin film, by increasing the glass transition temperature and the degradation temperature.

  5. Effects of electron-beam irradiation on conducting polypyrrole nanowires

    SciTech Connect

    Hong, Young Ki; Park, Dong Hyuk; Park, Se Hee; Park, Soung Kyu; Joo, Jinsoo

    2009-02-02

    Conducting polypyrrole (PPy) nanowires (NWs) were irradiated by a relatively high energy (300 keV-2 MeV) electron-beam (e-beam) generated from a linear electron accelerator in an atmospheric environment. From the current-voltage characteristics of pristine and 2 MeV e-beam irradiated PPy NWs, we observed a dramatic variation in resistance from 8.0x10{sup 2} to 1.45x10{sup 8} {omega}, that is, we observed a transition from conducting states to nonconducting states through the e-beam irradiation. To discern conformational changes and the doping states of PPy NWs through the e-beam irradiation, we measured Raman and ultraviolet-visible absorption spectra for the PPy NWs. As the energy of the e-beam irradiation increased, we observed that the PPy NWs were changed from doping states to dedoping states with conformational modification including the variation in {pi}-conjugation length.

  6. Concurrent in situ ion irradiation transmission electron microscope

    DOE PAGES

    Hattar, K.; Bufford, D. C.; Buller, D. L.

    2014-08-29

    An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

  7. Structural properties of amorphous silicon produced by electron irradiation

    SciTech Connect

    Yamasaki, J.; Takeda, S.

    1999-07-01

    The structural properties of the amorphous Si (a-Si), which was created from crystalline silicon by 2 MeV electron irradiation at low temperatures about 25 K, are examined in detail by means of transmission electron microscopy and transmission electron diffraction. The peak positions in the radial distribution function (RDF) of the a-Si correspond well to those of a-Si fabricated by other techniques. The electron-irradiation-induced a-Si returns to crystalline Si after annealing at 550 C.

  8. Electron beam irradiated silver nanowires for a highly transparent heater

    PubMed Central

    Hong, Chan-Hwa; Oh, Seung Kyu; Kim, Tae Kyoung; Cha, Yu-Jung; Kwak, Joon Seop; Shin, Jae-Heon; Ju, Byeong-Kwon; Cheong, Woo-Seok

    2015-01-01

    Transparent heaters have attracted increasing attention for their usefulness in vehicle windows, outdoor displays, and periscopes. We present high performance transparent heaters based on Ag nanowires with electron beam irradiation. We obtained an Ag-nanowire thin film with 48 ohm/sq of sheet resistance and 88.8% (substrate included) transmittance at 550 nm after electron beam irradiation for 120 sec. We demonstrate that the electron beam creates nano-soldering at the junctions of the Ag nanowires, which produces lower sheet resistance and improved adhesion of the Ag nanowires. We fabricated a transparent heater with Ag nanowires after electron beam irradiation, and obtained a temperature of 51 °C within 1 min at an applied voltage of 7 V. The presented technique will be useful in a wide range of applications for transparent heaters. PMID:26639760

  9. Electron beam irradiated silver nanowires for a highly transparent heater

    NASA Astrophysics Data System (ADS)

    Hong, Chan-Hwa; Oh, Seung Kyu; Kim, Tae Kyoung; Cha, Yu-Jung; Kwak, Joon Seop; Shin, Jae-Heon; Ju, Byeong-Kwon; Cheong, Woo-Seok

    2015-12-01

    Transparent heaters have attracted increasing attention for their usefulness in vehicle windows, outdoor displays, and periscopes. We present high performance transparent heaters based on Ag nanowires with electron beam irradiation. We obtained an Ag-nanowire thin film with 48 ohm/sq of sheet resistance and 88.8% (substrate included) transmittance at 550 nm after electron beam irradiation for 120 sec. We demonstrate that the electron beam creates nano-soldering at the junctions of the Ag nanowires, which produces lower sheet resistance and improved adhesion of the Ag nanowires. We fabricated a transparent heater with Ag nanowires after electron beam irradiation, and obtained a temperature of 51 °C within 1 min at an applied voltage of 7 V. The presented technique will be useful in a wide range of applications for transparent heaters.

  10. Fowler-Nordheim characteristics of electron irradiated MOS capacitors

    SciTech Connect

    Candelori, A.; Paccagnella, A.; Cammarata, M.; Ghidini, G.; Fuochi, P.G.

    1998-12-01

    MOS capacitors with 8 nm thick oxides have been irradiated by an 8 MeV LINAC electron beam. C-V and I-V measurements have shown a positive trapped charge, higher for irradiation performed under negative gate bias, as a consequence of preferential charge recombination at the cathodic interface. No saturation of the positive trapped charge is measured up to 20 Mrad(Si). Neutral defects induced by irradiation have been studied, by performing positive and negative Fowler-Nordheim injection. The distribution of neutral defects is similar to that of trapped holes, indicating a correlation between trapped holes and neutral defects. Electrical stresses performed after irradiation have shown that the accumulation kinetics of oxide defects is similar in both unirradiated and irradiated devices.

  11. Electron beam irradiation of gemstone for color enhancement

    NASA Astrophysics Data System (ADS)

    Idris, Sarada; Ghazali, Zulkafli; Hashim, Siti A'iasah; Ahmad, Shamshad; Jusoh, Mohd Suhaimi

    2012-09-01

    Numerous treatment of gemstones has been going on for hundreds of years for enhancing color and clarity of gems devoid of these attributes. Whereas previous practices included fraudulent or otherwise processes to achieve the color enhancement, the ionizing radiation has proven to be a reliable and reproducible technique. Three types of irradiation processes include exposure to gamma radiation, electron beam irradiation and the nuclear power plants. Electron Beam Irradiation of Gemstone is a technique in which a gemstone is exposed to highly ionizing radiation electron beam to knock off electrons to generate color centers culminating in introduction of deeper colors. The color centers may be stable or unstable. Below 9MeV, normally no radioactivity is introduced in the exposed gems. A study was conducted at Electron Beam Irradiation Centre (Alurtron) for gemstone color enhancement by using different kind of precious gemstones obtained from Pakistan. The study shows that EB irradiation not only enhances the color but can also improves the clarity of some type of gemstones. The treated stones included kunzite, tourmaline, topaz, quartz, aquamarine and cultured pearls. Doses ranging from 25 kGy to 200 KGy were employed to assess the influence of doses on color and clarity and to select the optimum doses. The samples used included both the natural and the faceted gemstones. It is concluded that significant revenue generation is associated with the enhancement of the color in clarity of gemstones which are available at very cheap price in the world market.

  12. Electron beam irradiation of gemstone for color enhancement

    SciTech Connect

    Idris, Sarada; Ghazali, Zulkafli; Hashim, Siti A'iasah; Ahmad, Shamshad; Jusoh, Mohd Suhaimi

    2012-09-26

    Numerous treatment of gemstones has been going on for hundreds of years for enhancing color and clarity of gems devoid of these attributes. Whereas previous practices included fraudulent or otherwise processes to achieve the color enhancement, the ionizing radiation has proven to be a reliable and reproducible technique. Three types of irradiation processes include exposure to gamma radiation, electron beam irradiation and the nuclear power plants. Electron Beam Irradiation of Gemstone is a technique in which a gemstone is exposed to highly ionizing radiation electron beam to knock off electrons to generate color centers culminating in introduction of deeper colors. The color centers may be stable or unstable. Below 9MeV, normally no radioactivity is introduced in the exposed gems. A study was conducted at Electron Beam Irradiation Centre (Alurtron) for gemstone color enhancement by using different kind of precious gemstones obtained from Pakistan. The study shows that EB irradiation not only enhances the color but can also improves the clarity of some type of gemstones. The treated stones included kunzite, tourmaline, topaz, quartz, aquamarine and cultured pearls. Doses ranging from 25 kGy to 200 KGy were employed to assess the influence of doses on color and clarity and to select the optimum doses. The samples used included both the natural and the faceted gemstones. It is concluded that significant revenue generation is associated with the enhancement of the color in clarity of gemstones which are available at very cheap price in the world market.

  13. Dynamic Void Growth and Shrinkage in Mg under Electron Irradiation

    SciTech Connect

    Xu, W. Z.; Zhang, Y. F.; Cheng, G. M.; Jian, W. W.; Millett, P. C.; Koch, C. C.; Mathaudhu, S. N.; Zhu, Y. T.

    2014-04-30

    We report in-situ atomic-scale investigation of void evolution, including growth, coalescence and shrinkage, under electron irradiation. With increasing irradiation dose, the total volume of voids increased linearly, while nucleation rate of new voids decreased slightly, and the total number of voids decreased. Some voids continued to grow while others shrank to disappear, depending on the nature of their interactions with nearby self-interstitial loops. For the first time, surface diffusion of adatoms was observed largely responsible for the void coalescence and thickening. These findings provide fundamental understanding to help with the design and modeling of irradiation-resistant materials.

  14. Semiconductor diode characterization for total skin electron irradiation.

    PubMed

    Madrid González, O A; Rivera Montalvo, T

    2014-01-01

    In this paper, a semiconductor diode characterization was performed. The diode characterization was completed using an electron beam with 4 MeV of energy. The semiconductor diode calibration used irradiation with an electron beam in an ion chamber. "In vivo" dosimetry was also conducted. The dosimetry results revealed that the semiconductor diode was a good candidate for use in the total skin electron therapy (TSET) treatment control.

  15. Effects of electron irradiation on LDPE/MWCNT composites

    NASA Astrophysics Data System (ADS)

    Yang, Jianqun; Li, Xingji; Liu, Chaoming; Rui, Erming; Wang, Liqin

    2015-12-01

    In this study, mutiwalled carbon nanotubes (MWCNTs) were incorporated into low density polyethylene (LDPE) in different concentrations (2%, 4% and 8%) using a melt blending process. Structural, thermal stability and tensile property of the unirradiated/irradiated LDPE/MWCNT composites by 110 keV electrons were investigated by means of scanning electron microscopy (SEM), small angle X-ray scattering (SAXS), Raman spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetric analysis (TGA) and uniaxial tensile techniques. Experimental results show that the addition of MWCNTs obviously increases the ultimate tensile strength of LDPE and decreases the elongation at break, which is attributed to the homogeneous distribution of the MWCNTs in LDPE and intense interaction between MWCNTs and LDPE matrix. Also, the electron irradiation further increases the ultimate tensile strength of LDPE/MWCNT composites, which can be ascribed to the more intense interaction between MWCNTs and LDPE matrix, and the formation of crosslinking sites in LDPE matrix induced by the electron irradiation. The addition of MWCNTs significantly enhances thermal stability of the LDPE due to the hindering effect and the scavenging free radicals, while the electron irradiation decreases thermal stability of the LDPE/MWCNT composites since the structure of the MWCNTs and LDPE matrix damages.

  16. In situ transmission electron microscope studies of irradiation-induced and irradiation-enhanced phase changes

    SciTech Connect

    Allen, C.W.

    1991-12-31

    Motivated at least initially by materials needs for nuclear reactor development, extensive irradiation effects studies employing TEMs have been performed for several decades, involving irradiation-induced and irradiation-enhanced, microstructural changes, including phase transformations such as precipitation, dissolution, crystallization, amorphization, and order-disorder phenomena. From the introduction of commercial high voltage electron microscopes (HVEM) in the mid-1960s, studies of electron irradiation effects have constituted a major aspect of HVEM application in materials science. For irradiation effects studies two additional developments have had particularly significant impact: (1) The availability of TEM specimen holders in which specimen temperature can be controlled in the range 10--2200 K; and (2) the interfacing of ion accelerators which allows in situ TEM studies of irradiation effects and the ion beam modification of materials within this broad temperature range. This paper treats several aspects of in situ studies of electron and ion beam-induced and enhanced phase changes, including the current state of in situ ion beam capability internationally, and presents two case studies involving in situ experiments performed in an HVEM to illustrate the dynamics of such an approach in materials research.

  17. In situ transmission electron microscope studies of irradiation-induced and irradiation-enhanced phase changes

    SciTech Connect

    Allen, C.W.

    1991-01-01

    Motivated at least initially by materials needs for nuclear reactor development, extensive irradiation effects studies employing TEMs have been performed for several decades, involving irradiation-induced and irradiation-enhanced, microstructural changes, including phase transformations such as precipitation, dissolution, crystallization, amorphization, and order-disorder phenomena. From the introduction of commercial high voltage electron microscopes (HVEM) in the mid-1960s, studies of electron irradiation effects have constituted a major aspect of HVEM application in materials science. For irradiation effects studies two additional developments have had particularly significant impact: (1) The availability of TEM specimen holders in which specimen temperature can be controlled in the range 10--2200 K; and (2) the interfacing of ion accelerators which allows in situ TEM studies of irradiation effects and the ion beam modification of materials within this broad temperature range. This paper treats several aspects of in situ studies of electron and ion beam-induced and enhanced phase changes, including the current state of in situ ion beam capability internationally, and presents two case studies involving in situ experiments performed in an HVEM to illustrate the dynamics of such an approach in materials research.

  18. Structural and luminescent properties of electron-irradiated silicon

    SciTech Connect

    Sobolev, N. A.; Loshachenko, A. S.; Aruev, P. N.; Kalyadin, A. E.; Shek, E. I.; Zabrodskiy, V. V.; Shtel'makh, K. F.; Vdovin, V. I.; Xiang, Luelue; Yang, Deren

    2014-02-21

    Structural defects induced by electron irradiation of p-Cz-Si wafers were identified. The influence of the annealing conditions in a chlorine-containing atmosphere on the structural and luminescent properties of the samples was examined. Light-emitting diodes based on electron-irradiated and high-temperature-annealed wafers were fabricated by a vapour-phase epitaxy technique and their luminescence properties were studied. A high-intensity dislocation-related D1 line was observed at 1.6 μm in the room-temperature electroluminescence spectrum.

  19. Electron trapping in rad-hard RCA IC's irradiated with electrons and gamma rays

    NASA Technical Reports Server (NTRS)

    Danchenko, V.; Brashears, S. S.; Fang, P. H.

    1984-01-01

    Enhanced electron trapping has been observed in n-channels of rad-hard CMOS devices due to electron and gamma-ray irradiation. Room-temperature annealing results in a positive shift in the threshold potential far beyond its initial value. The slope of the annealing curve immediately after irradiation was found to depend strongly on the gate bias applied during irradiation. Some dependence was also observed on the electron dose rate. No clear dependence on energy and shielding over a delidded device was observed. The threshold shift is probably due to electron trapping at the radiation-induced interface states and tunneling of electrons through the oxide-silicon energy barrier to fill the radiation-induced electron traps. A mathematical analysis, based on two parallel annealing kinetics, hole annealing and electron trapping, is applied to the data for various electron dose rates.

  20. Mechanical properties of hydrogenated electron-irradiated graphene

    NASA Astrophysics Data System (ADS)

    Weerasinghe, Asanka; Muniz, Andre R.; Ramasubramaniam, Ashwin; Maroudas, Dimitrios

    2016-09-01

    We report a systematic analysis on the effects of hydrogenation on the mechanical behavior of irradiated single-layer graphene sheets, including irradiation-induced amorphous graphene, based on molecular-dynamics simulations of uniaxial tensile straining tests and using an experimentally validated model of electron-irradiated graphene. We find that hydrogenation has a significant effect on the tensile strength of the irradiated sheets only if it changes the hybridization of the hydrogenated carbon atoms to sp3, causing a reduction in the strength of irradiation-induced amorphous graphene by ˜10 GPa. Hydrogenation also causes a substantial decrease in the failure strain of the defective sheets, regardless of the hybridization of the hydrogenated carbon atoms, and in their fracture toughness, which decreases with increasing hydrogenation for a given irradiation dose. We characterize in detail the fracture mechanisms of the hydrogenated irradiated graphene sheets and elucidate the role of hydrogen and the extent of hydrogenation in the deformation and fracture processes. Our study sets the stage for designing hydrogenation and other chemical functionalization strategies toward tailoring the properties of defect-engineered ductile graphene.

  1. A nanotube based electron microbeam cellular irradiator for radiobiology research

    SciTech Connect

    Bordelon, David E.; Zhang Jian; Graboski, Sarah; Cox, Adrienne; Schreiber, Eric; Chang, Sha; Zhou, Otto Z.

    2008-12-15

    A prototype cellular irradiator utilizing a carbon nanotube (CNT) based field emission electron source has been developed for microscopic image-guided cellular region irradiation. The CNT cellular irradiation system has shown great potential to be a high temporal and spatial resolution research tool to enable researchers to gain a better understanding of the intricate cellular and intercellular microprocesses occurring following radiation deposition, which is essential to improving radiotherapy cancer treatment outcomes. In this paper, initial results of the system development are reported. The relationship between field emission current, the dose rate, and the dose distribution has been investigated. A beam size of 23 {mu}m has been achieved with variable dose rates of 1-100 Gy/s, and the system dosimetry has been measured using a radiochromic film. Cell irradiation has been demonstrated by the visualization of H2AX phosphorylation at DNA double-strand break sites following irradiation in a rat fibroblast cell monolayer. The prototype single beam cellular irradiator is a preliminary step to a multipixel cell irradiator that is under development.

  2. A nanotube based electron microbeam cellular irradiator for radiobiology research

    NASA Astrophysics Data System (ADS)

    Bordelon, David E.; Zhang, Jian; Graboski, Sarah; Cox, Adrienne; Schreiber, Eric; Zhou, Otto Z.; Chang, Sha

    2008-12-01

    A prototype cellular irradiator utilizing a carbon nanotube (CNT) based field emission electron source has been developed for microscopic image-guided cellular region irradiation. The CNT cellular irradiation system has shown great potential to be a high temporal and spatial resolution research tool to enable researchers to gain a better understanding of the intricate cellular and intercellular microprocesses occurring following radiation deposition, which is essential to improving radiotherapy cancer treatment outcomes. In this paper, initial results of the system development are reported. The relationship between field emission current, the dose rate, and the dose distribution has been investigated. A beam size of 23 μm has been achieved with variable dose rates of 1-100 Gy/s, and the system dosimetry has been measured using a radiochromic film. Cell irradiation has been demonstrated by the visualization of H2AX phosphorylation at DNA double-strand break sites following irradiation in a rat fibroblast cell monolayer. The prototype single beam cellular irradiator is a preliminary step to a multipixel cell irradiator that is under development.

  3. Improvement in properties of plastic teeth by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Sano, Yuko; Ishikawa, Shun-ichi; Seguchi, Tadao

    2011-11-01

    Improvement of the comfort and esthetics of artificial plastic teeth is desirable for the recently increasing numbers of elderly in society. Plastic teeth made of polycarbonate (PC) were modified by electron beam (EB) irradiation under specific conditions, and the change in the chemical properties of the PC was investigated. The water absorption, glucose attachment, level of bis-phenol-A (BPA) extraction, maltose adhesion, and mucin adhesion on the PC teeth were measured before and after EB irradiation. EB irradiation to a dose of 3.5 kGy at 150 °C in a nitrogen gas atmosphere reduced the water absorption by 20%, glucose absorption by 40%, maltose adhesion by 20%, and the amount of various amino acids, formed as the hydrolysis products of mucin, adhering on the PC teeth were reduced by 60-99%. The BPA content was lower than the detection limit for analysis of both the original and the EB irradiated PC teeth.

  4. Effects of Electron Beam Irradiation on the Electrospinning of Polyacrylonitrile.

    PubMed

    Jeun, Joon-Pyo; Kim, Hyun-Bin; Oh, Seung-Hwan; Park, Jung-Ki; Kang, Phil-Hyun

    2015-08-01

    Electron beam (e-beam) irradiation of polyacrylonitrile (PAN) was performed to investigate the effects of radiation on the electrospinning process. For this study, polyacrylonitrile powder was subjected to e-beam irradiation with different doses of up to 100 kGy under an N2 atmosphere. Polymer solutions were prepared by dissolving PAN in N,N-dimethyl-formamide (DMF) at a 1:9 ratio by weight. The prepared PAN/DMF solutions showed different colors with different e-beam doses. The resulting structures in solutions contained conjugated C=N bonds, which caused the observed color formation. In addition, the conductivity of the PAN/DMF solution increased with an increase in e-beam irradiation dose. In the DSC spectra of electrospun PAN fibers, the peak temperature of the exothermic reactions was observed to decrease with an increase in the e-beam irradiation strength. PMID:26369176

  5. Modification of fluoropolymers by means of electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Lunkwitz, K.; Lappan, U.; Lehmann, D.

    2000-03-01

    High molecular weight polytetrafluoroethylene (PTFE) is transformed to free-flowing micropowder by treatment with electron beams. In case of irradiation in presence of air carboxylic acid fluoride groups are incorporated which rapidly hydrolyze to carboxylic groups in the surface-near regions due to atmospheric humidity. These polar groups reduce the hydrophobic and oleophobic properties so much that homogeneous compounding with other materials becomes possible. In addition to PTFE, copolymers of tetrafluoroethylene with hexafluoropropylene (FEP) and perfluoropropylvinylether (PFA) were modified. In case of identical irradiation conditions, the concentration of carboxylic groups is much higher in FEP and PFA than in PTFE, which is due to the lower crystallinity of the copolymers. Electron beam irradiation of PTFE was performed in vacuum at elevated temperature above the melting point. The changes in the chemical structure were studied. The concentration of CF 3 branches was found to be much higher as compared to room temperature irradiation. In a practical test PTFE micropowders functionalized by electron irradiation were compounded with epoxy resins, with polyoximethylene and with polyamides. Such compounds are characterized by very good frictional and wearing behaviour in dry-running tests.

  6. Fluorescence and phosphorescence of photomultiplier window materials under electron irradiation

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Eubanks, A. G.; Bredekamp, J. H.

    1974-01-01

    The fluorescence and phosphorescence of photomultiplier window materials under electron irradiation were investigated using a Sr-90/Y-90 beta emitter as the electron source. Spectral emission curves of UV grade, optical grade, and electron-irradiated samples of MGF2 and LiF, CaF2, BaF2, sapphire, fused silica, and UV transmitting glasses were obtained over the spectral range of 200 nm to 650 nm. Fluorescence yields, expressed as the number of counts in a solid angle of 2 pi steradian per 1MeV of incident electron energy deposited, were determined on these materials utilizing photomultiplier tubes with cesium telluride, bialkali, and trialkali (S-20) photocathodes, respectively.

  7. Synthesis and controlled growth of osmium nanoparticles by electron irradiation.

    PubMed

    Pitto-Barry, Anaïs; Perdigao, Luis M A; Walker, Marc; Lawrence, James; Costantini, Giovanni; Sadler, Peter J; Barry, Nicolas P E

    2015-12-21

    We have synthesised osmium nanoparticles of defined size (1.5-50 nm) on a B- and S-doped turbostratic graphitic structure by electron-beam irradiation of an organometallic osmium complex encapsulated in self-spreading polymer micelles, and characterised them by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and atomic force microscopy (AFM) on the same grid. Oxidation of the osmium nanoparticles after exposure to air was detected by X-ray photoelectron spectroscopy (XPS). PMID:26418726

  8. Gamma and electron-beam irradiation of cut flowers

    NASA Astrophysics Data System (ADS)

    Kikuchi, Olivia Kimiko

    2003-01-01

    Fresh cut flowers are commodities that require quarantine treatment for export/import. In the present work some cut flowers were irradiated in a gamma panoramic source and in an electron beam accelerator with doses up to 800 Gy, and the results for the radiation tolerance of the flowers are presented.

  9. Investigation of the effect of some irradiation parameters on the response of various types of dosimeters to electron irradiation

    NASA Astrophysics Data System (ADS)

    Farah, K.; Kuntz, F.; Kadri, O.; Ghedira, L.

    2004-09-01

    Several undyed and dyed polymer films are commercially available for dosimetry in intense radiation fields, especially for radiation processing of food and sterilisation of medical devices. The effects of temperature during irradiation and post-irradiation stability, on the response of these dosimeters are of importance to operators of irradiation facilities. The present study investigates the effects of temperature during irradiation by 2.2 MeV electrons beam accelerator and post irradiation storage on the response of several types of dosimeter films. All dosimeters showed a significant effect of temperature during irradiation and post-irradiation storage.

  10. Reinforcing multiwall carbon nanotubes by electron beam irradiation

    SciTech Connect

    Duchamp, Martial; Meunier, Richard; Smajda, Rita; Mionic, Marijana; Forro, Laszlo; Magrez, Arnaud; Seo, Jin Won; Song, Bo; Tomanek, David

    2010-10-15

    We study the effect of electron beam irradiation on the bending modulus of multiwall carbon nanotubes grown by chemical vapor deposition. Atomic force microscopy observations of the nanotube deflection in the suspended-beam geometry suggest an internal, reversible stick-slip motion prior to irradiation, indicating presence of extended defects. Upon electron beam irradiation, nanotubes with an initial bending modulus exceeding 10 GPa initially get stiffer, before softening at high doses. Highly defective nanotubes with smaller initial bending moduli do not exhibit the initial reinforcement. These data are explained by ab initio molecular dynamics calculations suggesting a spontaneous cross-linking of neighboring nanotube walls at extended vacancy defects created by the electron beam, in agreement with electron microscopy observations. At low defect concentration, depending on the edge morphology, the covalent bonds between neighboring nanotube walls cause reinforcement by resisting relative motion of neighboring walls. At high concentration of defects that are present initially or induced by high electron beam dose, the structural integrity of the entire system suffers from increasing electron beam damage.

  11. Electron spin resonance spectral analysis of irradiated royal jelly.

    PubMed

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2014-01-15

    The analysis of unpaired electron components in royal jelly was carried out using electron spin resonance (ESR) with the aim to develop a detection method for irradiated royal jelly. The ESR spectrum of royal jelly had natural signals derived from transition metals, including Fe(3+) and Cu(2+), and a signal line near g=2.00. After irradiation, a new splitting asymmetric spectrum with overall spectrum width ca. 10mT at g=2.004 was observed. The intensities of the signals at g=2.004 increased in proportion to the absorbed dose in samples under different storage conditions: fresh frozen royal jelly and dried royal jelly powder at room temperature. The signal intensity of the fresh frozen sample was stable after irradiation. One year after 10kGy irradiation of dried powder, the signal intensity was sevenfold greater than before irradiation, although the intensity continued to steadily decrease with time. This stable radiation-induced radical component was derived from the poorly soluble constituent of royal jelly.

  12. Identification of irradiated cashew nut by electron paramagnetic resonance spectroscopy.

    PubMed

    Sanyal, Bhaskar; Sajilata, M G; Chatterjee, Suchandra; Singhal, Rekha S; Variyar, Prasad S; Kamat, M Y; Sharma, Arun

    2008-10-01

    Cashew nut samples were irradiated at gamma-radiation doses of 0.25, 0.5, 0.75, and 1 kGy, the permissible dose range for insect disinfestation of food commodities. A weak and short-lived triplet (g = 2.004 and hfcc = 30 G) along with an anisotropic signal (g perpendicular = 2.0069 and g parallel = 2.000) were produced immediately after irradiation. These signals were assigned to that of cellulose and CO 2 (-) radicals. However, the irradiated samples showed a dose-dependent increase of the central line (g = 2.0045 +/- 0.0002). The nature of the free radicals formed during conventional processing such as thermal treatment was investigated and showed an increase in intensity of the central line (g = 2.0045) similar to that of irradiation. Characteristics of the free radicals were studied by their relaxation and thermal behaviors. The present work explores the possibility to identify irradiated cashew nuts from nonirradiated ones by the thermal behaviors of the radicals beyond the period, when the characteristic electron paramagnetic resonance spectral lines of the cellulose free radicals have essentially disappeared. In addition, this study for the first time reports that relaxation behavior of the radicals could be a useful tool to distinguish between roasted and irradiated cashew nuts.

  13. Influence of irradiation upon few-layered graphene using electron-beams and gamma-rays

    SciTech Connect

    Wang, Yuqing; Feng, Yi Mo, Fei; Qian, Gang; Chen, Yangming; Yu, Dongbo; Wang, Yang; Zhang, Xuebin

    2014-07-14

    Few-layered graphene (FLG) is irradiated by electron beams and gamma rays. After 100 keV electron irradiation, the edges of FLG start bending, shrinking, and finally generate gaps and carbon onions due to sputtering and knock-on damage mechanism. When the electron beam energy is increased further to 200 keV, FLG suffers rapid and catastrophic destruction. Unlike electron irradiation, Compton effect is the dominant damage mechanism in gamma irradiation. The irradiation results indicate the crystallinity of FLG decreases first, then restores as increasing irradiation doses, additionally, the ratio (O/C) of FLG surface and the relative content of oxygen groups increases after irradiation.

  14. Ion irradiation damage in n-type GaAs in comparison with its electron irradiation damage

    NASA Astrophysics Data System (ADS)

    Eisen, F. H.; Bachem, K.; Klausman, E.; Koehler, K.; Haddad, R.

    1992-12-01

    In an effort to attain a better understanding of the nature of the defects introduced in GaAs by irradiating it with energetic light ions; electron or proton irradiated n-type GaAs samples, cut from the same layer grown by molecular-beam epitaxy, have been studied by deep level transient spectroscopy. By comparing the spectra, including the effects of high electric fields, and by using results for annealed samples, it is possible to determine which of the traps reported in electron irradiated GaAs, most of which are believed to be arsenic interstitial-vacancy pairs, are present in the proton irradiated material. The traps identified in proton irradiated GaAs include most of those found in electron irradiated material, either after irradiation or after irradiation and annealing. The results indicate that two of these traps are associated with defects which are more complex than simple interstitial-vacancy pairs. Two traps were found in proton irradiated material which have not been observed in electron irradiated GaAs. One of these is nearly as abundant as the prominent E3 center observed in electron irradiated GaAs and is probably also not a simple pair. The deep level transient spectroscopy peak for this trap is not clearly separated from that of E3 in proton irradiated GaAs. The other trap is probably associated with a particular impurity present in the MBE grown sample layers.

  15. Electrostatic discharging behaviour of Kapton irradiated with electrons

    NASA Technical Reports Server (NTRS)

    Verdin, D.

    1981-01-01

    The electrostatic charging and discharging of Kapton when irradiated with monoenergetic electrons of 5 to 30 keV energy were studied. The leakage currents and rates of discharging always increased with the incident electron energy and flux, whereas the surface voltage showed a more complex behavior depending on the thickness of the material: for the thinner films it exhibited a maximum and then fell at higher energies. The surface voltage, the rate of discharging, and the peak current and total charge flow during a discharge were enhanced as the temperature was decreased from 70 C to -180 C, and were accompanied by a decreasing leakage current. Visible light or the presence of an aluminum coating on the irradiated surface caused reductions in the surface voltage and changes in the discharging characteristics. The results are discussed in terms of the leakage currents and the secondary emission of electrons. Photomicrographs taken after irradiation, and photographs of samples during irradiation, show good correlations between the positions of light flashes and of pinholes produced by the discharge arcs.

  16. Radiolytic Impacts of Energetic Electron Irradiation on Enceladus and Mimas

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.; Sittler, E. C.; Sturner, S. J.

    2011-01-01

    Episodic overturn of the south polar terrain on Enceladus would convey radio lytic oxidants from surface irradiation by Saturn's inner magnetospheric electrons to the putative underlying polar sea and contribute to CO2 and other gas production driving the visibly active cryovolcanism. Low duty cycle of active episodes below 1 - 10 percent would raise the relative importance of the continuous radiolytic chemical energy input for mass and heat outflow, e.g. as compared to heating by gravitational tides. The "Pac-Man" thermal anomaly on Mimas most likely arises from leading-trailing asymmetry of electron irradiation and resultant radio lytic processing of the moon ice to a few centimeters of depth. The Mimas thermal anomaly distribution suggests a relatively stable surface unmodified by Enceladus-like geologic overturn or cryovolcanic activity. In both cases, the heavily irradiated skin depth corresponds to the sensible thermal layer probed by Cassini infrared measurements. Neutral gas and dust emissions from Enceladus limit energetic ion and plasma electron fluxes in the inner magnetosphere, thereby governing the irradiation of Mimas and other Saturn moons.

  17. Electron irradiation effects in epitaxial InP solar cells

    NASA Technical Reports Server (NTRS)

    Pearsall, N. M.; Robson, N.; Sambell, A. J.; Anspaugh, B.; Cross, T. A.

    1991-01-01

    Performance data for InP-based solar cells after irradiation with 1-MeV electrons up to a fluence of 1 x 1016 e/cm2 are presented. Three InP cell structures are considered. Two of these have epitaxially grown active regions, these being a homojunction design and in ITO/InP structure. These are compared with ITO/InP cells without the epitaxial base region. The cell parameter variations, the influence of illumination during irradiation, and the effect on cell spectral response and capacitance measurements are discussed. Substantial performance recovery after thermal annealing at 90 C is reported.

  18. Investigation on the radiation induced conductivity of space-applied polyimide under cyclic electron irradiation

    NASA Astrophysics Data System (ADS)

    Yue, Long; Wu, Yiyong; Sun, Chengyue; Xiao, Jingdong; Shi, Yaping; Ma, Guoliang; He, Shiyu

    2012-11-01

    Radiation induced conductivity (RIC) is an important property of dielectric materials to evaluate the charge/discharge effect in orbit-service spacecraft. RIC of space-applied polyimide film was in situ measured and studied under continuous and cyclic electron irradiation in this paper. The results indicate that, for cyclic electron irradiation, there is a similar increasing-mode of RIC to those for continuous irradiation with the electron irradiation time. However, under the cyclic electron irradiation, the RIC of polyimide shows an obvious irradiation-history characteristic, namely preliminary irradiation dose effect (PIDE). In this case, the steady RIC value presents an "overshoot" behavior in the first few irradiation cycles and then decrease to a stable one as that under continuous irradiation. Prolonging the initial irradiation duration may avoid occurrence of overshoot phenomenon. The behaviors of irradiation-induced free radicals in polyimide could be applied to explain the RIC evolution processes.

  19. Vaccine Biotechnology by Accelerated Electron Beam and Microwave Irradiation

    NASA Astrophysics Data System (ADS)

    Craciun, Gabriela D.; Togoe, Iulian I.; Tudor, Laurentiu M.; Martin, Diana I.; Manaila, Elena N.; Ighigeanu, Daniel I.; Iacob, Nicusor I.; Oproiu, Constantin V.

    2007-04-01

    A new biotechnology for obtaining a commercial vaccine that contains either Fusobacterium necrophorum (F.n.) exotoxins inactivated by accelerated electron beam (EB) and microwave (MW) irradiation, or exotoxins isolated from F.n. cultures irradiated with EB+MW, is presented. This vaccine is designed for prophylaxis of ruminant infectious pododermatitis (IP) produced by F.n. Also, the research results concerning the effects of combined chemical adjuvant and EB+MW irradiation on F.n. immune capacity are discussed. The vaccine's efficacy will be tested in ruminant farms in which IP evolves. It is expected that this new vaccine to offer a better protection, more than 60%, which is the best presently obtained result in ruminant farms.

  20. Photomultiplier window materials under electron irradiation - Fluorescence and phosphorescence

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Eubanks, A. G.; Pieper, G. F.; Bredekamp, J. H.

    1975-01-01

    The fluorescence and phosphorescence of photomultiplier window materials under electron irradiation have been investigated using a Sr-90/Y-90 beta emitter as the electron source. Spectral emission curves of UV-grade, optical-grade, and electron-irradiated samples of MgF2 and LiF, and of CaF2, BaF2, sapphire, fused silica, and UV-transmitting glasses were obtained over the 200-650-nm spectral range. Fluorescence yields were determined on these materials utilizing photomultiplier tubes with cesium telluride, bialkali, and trialkali (S-20) photocathodes, respectively. Optical-grade MgF2 and LiF, as well as electron-irradiated UV-grade samples of these two materials, show enhanced fluorescence due to color-center formation and associated emission bands in the blue and red wavelength regions. Large variations in fluorescence intensities were found in UV-grade sapphire samples of different origins, particularly in the red end of the spectrum, presumably due to various amounts of chromium-ion content. Phosphorescence decay with time is best described by a sum of exponential terms, with time constants ranging from a few minutes to several days.

  1. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  2. Defect distribution near the surface of electron-irradiated silicon

    NASA Technical Reports Server (NTRS)

    Wang, K. L.; Lee, Y. H.; Corbett, J. W.

    1978-01-01

    The surface-defect distributions of electron-irradiated n-type silicon have been investigated using a transient capacitance technique. Schottky, p-n junction, and MOS structures were used in profiling the defect distributions. Surface depletions of defects observed were attributed to the vacancy distribution, but not that of oxygen, and other capture centers' distributions. The vacancy diffusion length at 300 K was estimated to be about 3-6 microns.

  3. Characteristics of PVDF Membranes Irradiated by Electron Beam

    PubMed Central

    Jaleh, Babak; Gavary, Negin; Fakhri, Parisa; Muensit, Nakatan; Taheri, Soheil Mohammad

    2015-01-01

    Polyvinylidene fluoride (PVDF) membranes were exposed vertically to a high energy electron beam (EB) in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphologies were studied by Scanning Electron Microscopy (SEM) and showed some changes in the pore size. Thermogravimetric (TGA) analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR) showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane. PMID:25569360

  4. Effects of electron beam irradiation of cellulose acetate cigarette filters

    NASA Astrophysics Data System (ADS)

    Czayka, M.; Fisch, M.

    2012-07-01

    A method to reduce the molecular weight of cellulose acetate used in cigarette filters by using electron beam irradiation is demonstrated. Radiation levels easily obtained with commercially available electron accelerators result in a decrease in average molecular weight of about six-times with no embrittlement, or significant change in the elastic behavior of the filter. Since a first step in the biodegradation of cigarette filters is reduction in the filter material's molecular weight this invention has the potential to allow the production of significantly faster degrading filters.

  5. An experimental investigation of wastewater treatment using electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Emami-Meibodi, M.; Parsaeian, M. R.; Amraei, R.; Banaei, M.; Anvari, F.; Tahami, S. M. R.; Vakhshoor, B.; Mehdizadeh, A.; Fallah Nejad, N.; Shirmardi, S. P.; Mostafavi, S. J.; Mousavi, S. M. J.

    2016-08-01

    Electron beam (EB) is used for disinfection and treatment of different types of sewage and industrial wastewater. However, high capital investment required and the abundant energy consumed by this process raise doubts about its cost-effectiveness. In this paper, different wastewaters, including two textile sewages and one municipal wastewater are experimentally studied under different irradiation strategies (i.e. batch, 60 l/min and 1000 m3/day) in order to establish the reliability and the optimum conditions for the treatment process. According to the results, EB improves the efficiency of traditional wastewater treatment methods, but, for textile samples, coagulation before EB irradiation is recommended. The cost estimation of EB treatment compared to conventional methods shows that EB has been more expensive than chlorination and less expensive than activated sludge. Therefore, EB irradiation is advisable if and only if conventional methods of textile wastewater treatment are insufficient or chlorination of municipal wastewater is not allowed for health reasons. Nevertheless, among the advanced oxidation processes (AOP), EB irradiation process may be the most suitable one in industrial scale operations.

  6. Oxidative decomposition of aromatic hydrocarbons by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Han, Do-Hung; Stuchinskaya, Tatiana; Won, Yang-Soo; Park, Wan-Sik; Lim, Jae-Kyong

    2003-05-01

    Decomposition of aromatic volatile organic compounds (VOCs) under electron beam irradiation was studied in order to examine the kinetics of the process, to characterize the reaction product distribution and to develop a process of waste gas control technology. Toluene, ethylbenzene, o-, m-, p-xylenes and chlorobenzene were used as target materials. The experiments were carried out at doses ranging from 0.5 to 10 kGy, using a flow reactor utilized under electron beam irradiation. Maximum degrees of decomposition carried out at 10 kGy in air environment were 55-65% for “non-chlorinated” aromatic VOC and 85% for chlorobenzene. It was found that a combination of aromatic pollutants with chlorobenzene would considerably increase the degradation value up to nearly 50% compared to the same compounds in the absence of chlorine groups. Based on our experimental observation, the degradation mechanism of the aromatic compounds combined with chloro-compound suggests that a chlorine radical, formed from EB irradiation, induces a chain reaction, resulting in an accelerating oxidative destruction of aromatic VOCs.

  7. Effects of electron irradiation on the properties of GZO films deposited with RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kim, Y. S.; Heo, S. B.; Lee, H. M.; Lee, Y. J.; Kim, I. S.; Kang, M. S.; Choi, D. H.; Lee, B. H.; Kim, M. G.; Kim, Daeil

    2012-02-01

    Transparent conductive GZO films were deposited on polycarbonate substrates by electron beam assisted radio frequency (RF) magnetron sputtering and then the influence of electron irradiation on the structural, optical and electrical properties of GZO films was investigated by using X-ray diffractometry, UV-vis spectrophotometry, four point probes, atomic force microscopy and UV photoelectron spectroscopy. Sputtering power was kept constant at 3 W/cm2 during deposition, while electron irradiation energy varied from 450 to 900 eV. Electron irradiated GZO films show larger grain sizes than those of films prepared without electron irradiation, and films irradiated at 900 eV show higher optical transmittance in the visible wavelength region and lower sheet resistance (120 Ω/□) than other films. The work-function is also increased with electron irradiation energy. The highest work-function of 4.4 eV was observed in films that were electron irradiated at 900 eV.

  8. Effect of free electron laser (FEL) irradiation on tooth dentine

    NASA Astrophysics Data System (ADS)

    Ogino, Seiji; Awazu, Kunio; Tomimasu, Takio

    1996-12-01

    Free electron laser (FEL) gives high efficiency for the photo-induced effects when the laser is tuned to the absorption maximum of target materials. The effect on dentine was investigated using the FEL tuned to 9.4 micrometers , which is an absorption maximum of phosphoric acid in infrared region. As a result, irradiated dentine surface which was amorphous had changed to the recrystalized structure by the spectroscopic analysis of IR absorption and x-ray diffraction. Furthermore, the atomic ratio of P/Ca had reduced from 0.65 to 0.60. These results indicated that 9.4micrometers -FEL irradiation caused the selective ablation of phosphoric acid ion and the reconstruction of disordered atoms.

  9. Hall effect study of electron irradiated Si(Li)

    NASA Technical Reports Server (NTRS)

    Stannard, J.

    1971-01-01

    Measurement of the Hall coefficient as a function of temperature between 15 and 300 K allows the separate determination of donor and acceptor concentrations in silicon samples which were irradiated at 240 K by 1-MeV electrons and then thermally annealed at 300 K. In both lithium- and phosphorus-doped silicon irradiation increased the acceptor concentration and decreased the donor concentration due to the formation of vacancy donor pairs. Annealing did not change either concentration in phosphorus-doped silicon and caused both concentrations to decrease in silicon doped with moderate amounts of lithium. In addition to this, in both lithium- and phosphorus-doped silicon the concentration and energy level of the A center were measured at each point in the sample's history. This experiment was limited to float-zoned silicon doped with less than 6 x 10 to the 14th power donors per cu cm.

  10. Recombination luminescence from electron-irradiated Li-diffused Si

    NASA Technical Reports Server (NTRS)

    Johnson, E. S.; Compton, W. D.; Noonan, J. R.; Streetman, B. G.

    1973-01-01

    Lithium doping has a dramatic effect on the low-temperature photoluminescence of electron-irradiated Si. In oxigen-lean Si with Li doping, a new irradiation-dependent luminescence band between 0.75 and 1.05 eV is observed, which is dominated by a zero-phonon peak at 1.045 eV. This band is believed to be due to radiative transitions involving a Li-modified divacancy. This band is present also in oxygen-rich, Li-diffused Si and is accompanied by bands previously related to the Si-G15(K) center and the divacancy. The intensities of the Li-modified divacancy and Si-G15(K) center bands are relatively weak in the oxygen-rich material, apparently due to the formation of lithium-oxygen complexes which reduce the concentration of unassociated interstitial Li and O.

  11. Electron irradiation damage in quartz, SiO2

    NASA Astrophysics Data System (ADS)

    Martin, B.; Flörke, O. W.; Kainka, E.; Wirth, R.

    1996-10-01

    Crystallographically orientated samples of synthetic optical-grade colourless quartz with high chemical purity and low dislocation density together with synthetic gem-grade amethyst with high Fe-concentration and ca. 250 H/106 Si (“dry”) or 600 H/106 Si (“wet”) and with very high dislocation densities were irradiated using TEM. Samples of cuts perpendicular (-cuts) and parallel (-cuts) to the c-axis, that were as-grown or pretreated for 5 days at 820 K on air or under p(H2O)=108 Pa were prepared. Characterization methods used include AAS, FTIR, Raman-spectroscopy, X-ray-topography, REM, TEM in SAED and bright-field mode and polarized light microscopy. Radiolysis was carried out in TEM from 10 to 300 K with 100 kV and from 70 850 K (low-high-transition temperature of quartz) with 200 kV. Irradiation damage was investigated by decay of Kikuchi-lines or of Bragg reflections in SAED and in bright-field mode by development of strain contrast centres and of noncrystalline volume areas. Special preparates where the irradiation damage was of microscopic dimensions were investigated using Raman-spectroscopy. Radiolysis of quartz is able to proceed at 10 K with measurable velocity. The required electron dose for a standardized irradiation damage decreases with increasing temperature. At ca. 500 K it goes through a minimum and then increases steadily up to ca. 700 K. From there the increase is steep until ca. 820 K where it culminates sharply, showing strong fluctuations until 850 K. The -cuts in the as-grown state show significantly higher irradiation damage sensitivity than -cuts. Dry or hydrothermal preheating increases the overall sensitivity of irradiation damage and levels out the orientation differences. The high Fe-concentrations in amethyst in comparison with very pure quartz have no detectable influence on the damage sensitivity. This is also true for different water concentrations independently from the ratio of silanole-group to molecular

  12. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  13. Tailoring crystallinity and configuration of silica nanotubes by electron irradiation

    NASA Astrophysics Data System (ADS)

    Taguchi, Tomitsugu; Yamaguchi, Kenji

    2015-05-01

    SiO2 nanotubes show potential in applications such as nanoscale electronic and optical devices, bioseparation, biocatalysis, and nanomedicine. As-grown SiO2 nanotubes in the previous studies always have an amorphous wall, and here we demonstrate the successful synthesis of single-crystal nanotubes for the first time by the heat treatment of SiC nanotubes at 1300 °C for 10 h under low-vacuum conditions. According to TEM observations, the single-crystal SiO2 was α-cristobalite. We also demonstrate that single-crystal SiO2 nanotubes can be transformed into amorphous SiO2 nanotubes by electron beam irradiation. Moreover, we synthesized a crystalline/amorphous SiO2 composite nanotube, in which crystalline and amorphous SiO2 coexisted in different localized regions. In addition, for biomedical applications such as drug delivery systems, controlling the configuration of the open end, the diameter, and capsulation of SiO2 nanotubes is crucial. We can also obturate, capsulate, and cut a SiO2 nanotube, as well as modify the inner diameter of the nanotube at a specific, nanometer-sized region using the focused electron beam irradiation technique.

  14. Electron Beam Irradiated Intercalated CNT Yarns For Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Waters, Deborah L.; Gaier, James R.; Williams, Tiffany S.; Lopez Calero, Johnny E.; Ramirez, Christopher; Meador, Michael A.

    2015-01-01

    Multi-walled CNT yarns have been experimentally and commercially created to yield lightweight, high conductivity fibers with good tensile properties for application as electrical wiring and multifunctional tendons. Multifunctional tendons are needed as the cable structures in tensegrity robots for use in planetary exploration. These lightweight robust tendons can provide mechanical strength for movement of the robot in addition to power distribution and data transmission. In aerospace vehicles, such as Orion, electrical wiring and harnessing mass can approach half of the avionics mass. Use of CNT yarns as electrical power and data cables could reduce mass of the wiring by thirty to seventy percent. These fibers have been intercalated with mixed halogens to increase their specific electrical conductivity to that near copper. This conductivity, combined with the superior strength and fatigue resistance makes it an attractive alternative to copper for wiring and multifunctional tendon applications. Electron beam irradiation has been shown to increase mechanical strength in pristine CNT fibers through increased cross-linking. Both pristine and intercalated CNT yarns have been irradiated using a 5-megavolt electron beam for various durations and the conductivities and tensile properties will be discussed. Structural information obtained using a field emission scanning electron microscope, energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy will correlate microstructural details with bulk properties.

  15. Microbial Safety Improvement of Sea Buckthorn by Electron Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Nemţanu, Monica R.; Minea, R.; Mazilu, Elena; Rǎdulescu, Nora

    2007-04-01

    The commercialization of medicinal plants and/or their products is highly increased in Romania lately. One of the most used herbs is sea buckthorn being well known for its quality with a large potential for curing some diseases. Sea buckthorn can be contaminated with undesirable microorganisms which may affect negatively its quality. The paper presents the results regarding the action of a non-conventional technology meaning electron beam technique on sea buckthorn in order to improve its microbiological quality. Our study revealed that the sea buckthorn microbial load has been improved after 3 kGy irradiation keeping its active principles.

  16. Microbial Safety Improvement of Sea Buckthorn by Electron Beam Irradiation

    SciTech Connect

    Nemtanu, Monica R.; Minea, R.; Mazilu, Elena; Radulescu, Nora

    2007-04-23

    The commercialization of medicinal plants and/or their products is highly increased in Romania lately. One of the most used herbs is sea buckthorn being well known for its quality with a large potential for curing some diseases. Sea buckthorn can be contaminated with undesirable microorganisms which may affect negatively its quality. The paper presents the results regarding the action of a non-conventional technology meaning electron beam technique on sea buckthorn in order to improve its microbiological quality. Our study revealed that the sea buckthorn microbial load has been improved after 3 kGy irradiation keeping its active principles.

  17. Irradiation effects in close binaries in an electron scattering medium

    NASA Astrophysics Data System (ADS)

    Varghese, B. A.; Srinivasa Rao, M.

    2016-03-01

    In a close binary system, the effects of irradiation are studied from an extended surface of the secondary component on the atmosphere of the primary. Primary and the secondary components are assumed to have equal radii and the thickness of the atmosphere is assumed to be twice that of the stellar radius of the primary component. Self radiation of the primary component (Ss) is calculated through a numerical solution of line transfer equation in the comoving frame with Compton broadening due to electron scattering. The solution is developed through discrete space theory to deal with different velocities in a spherically expanding medium. The irradiation from the secondary (SI) is calculated using one dimensional rod model. It is assumed to be one, five and ten times the self radiation. The total source function (S=Ss+SI) is the sum of the source functions due to self radiation and that due to irradiation. The line fluxes are computed along the line of sight by using the above source functions. Line profiles are also computed for different line center optical depths along the line of sight of the observer at infinity.

  18. A new electron paramagnetic resonance method to identify irradiated soybean.

    PubMed

    Sanyal, Bhaskar; Sharma, Arun

    2009-10-01

    Low-dose gamma irradiation causes minimal changes in food matrix making identification of radiation-processed foods a challenging task. In the present study, soybean samples were irradiated with commercially permitted gamma radiation dose in the 0.25 to 1.0 kGy range for insect disinfestations of food. Immediately after irradiation electron paramagnetic resonance (EPR) spectrum of the skin part of soybean showed a triplet signal (g = 2.0046, hyperfine coupling constant hfcc = 3.0 mT) superimposed on naturally present singlet. These signals were characterized as cellulose and phenoxyl radicals using EPR spectrum simulation technique. Kernel part of the samples exhibited a short-lived, radiation-induced singlet of carbon-centered radical superimposed on naturally present sextet signal of Mn2+. A detailed study on relaxation and thermal behavior of induced radicals in skin part was carried out using EPR spectroscopy. These findings revealed that progressive saturation and thermal characteristics of the induced radicals may be the most suitable parameters to distinguish soybean subjected to radiation dose as low as 0.25 kGy from thermally treated and nonirradiated samples, even after a prolonged period of storage.

  19. A scanning electron microscopic study of microvascular anastomoses on irradiated vessels: short-term effect of irradiation

    SciTech Connect

    De Wilde, R.; Boeckx, W.; Van Der Schueren, E.; Guelinckx, P.; Gruwez, J.

    1983-01-01

    Experiments were carried out to determine the effect of previous irradiation on microvascular arterial anastomoses. The study focused on regeneration of endothelial cells and thrombus formation. Careful examination with scanning electron microscopy (SEM) showed a difference between irradiated animals and a control group. In the irradiated group one can notice a decreased regeneration, a greater amount of fibrin and platelets, and a higher incidence of microthrombi.

  20. Electronic properties and deep traps in electron-irradiated n-GaN

    SciTech Connect

    Brudnyi, V. N.; Verevkin, S. S.; Govorkov, A. V.; Ermakov, V. S.; Kolin, N. G.; Korulin, A. V.; Polyakov, A. Ya.; Smirnov, N. B.

    2012-04-15

    The study is concerned with the effect of electron irradiation (with the energies E = 7 and 10 MeV and doses D = 10{sup 16}-10{sup 18} cm{sup -2}) and subsequent heat treatments in the temperature range 100-1000 Degree-Sign C on the electrical properties and the spectrum of deep traps of undoped (concentration of electrons n = 1 Multiplication-Sign 10{sup 14}-1 Multiplication-Sign 10{sup 16} cm{sup -3}), moderately Si-doped (n = (1.2-2) Multiplication-Sign 10{sup 17} cm{sup -3}), and heavily Si-doped (n = (2-3.5) Multiplication-Sign 10{sup 18} cm{sup -3}) epitaxial n-GaN layers grown on Al{sub 2}O{sub 3} substrates by metal-organic chemical vapor deposition. It is found that, on electron irradiation, the resistivity of n-GaN increases, this is due to a shift of the Fermi level to the limiting position close to E{sub c} -0.91 eV. The spectrum of deep traps is studied for the initial and electron-irradiated n-GaN. It is shown that the initial properties of the irradiated material are restored in the temperature range 100-1000 Degree-Sign C, with the main stage of the annealing of radiation defects at about 400 Degree-Sign C.

  1. GaAs detectors irradiated by low doses of electrons

    NASA Astrophysics Data System (ADS)

    Šagátová, A.; Zat'ko, B.; Pavlovič, M.; Sedlačková, K.; Hybler, P.; Dubecký, F.; Nečas, V.

    2014-04-01

    Semi-insulating (SI) GaAs detectors were irradiated by 5 MeV electrons up to a dose of 69 kGy, in order to test their radiation hardness. The electric and spectrometric stability of detectors was examined as a function of the absorbed dose. Investigated detectors showed a very good detector radiation resistance within a dose up to 40 kGy followed by deterioration of some spectrometric and electric properties. However, the reverse current and the detector charge collection efficiency showed minimum changes with the overall applied doses. The obtained results will be used as a preliminary study for further radiation-hardness investigations of GaAs detectors against high energy electrons. This will complete our previous studies of GaAs detector radiation hardness against fast neutrons and γ-rays.

  2. Dose quality assurance for industrial irradiation with an electron linac

    NASA Astrophysics Data System (ADS)

    White, B. F.; Lawrence, C. B.; Lee-Whiting, G. E.; Lord, S.; Mason, V. A.; Smyth, D. L.; Ungrin, J.

    1989-04-01

    In the development of the IMPELA family of electron linacs for industrial radiation processing, the needs for on-line monitoring of exposure dose have been recognized. The diverse applications under consideration demand a broad range of control-system performance and delivered-dose assurance measures appropriate to the sensitivities of the processes. The AAMI Guideline for Electron Beam Radiation Sterilization of Medical Devices points to a probable upper bound to the complexity of such requirements. ASTM and IAEA standards and guidelines for radiation dosimetry define the methods available for off-line verification of absorbed dose. The impact of the requirements for on-line measurements and the limitations inherent to the IMPELA design, are reviewed. The interdependencies of off-line product dosimetry and analyses with the on-line monitoring of process parameters are explored in search of criteria for optimization of cost-effective, flexible industrial irradiators.

  3. Simulation of Electronic Center Formation by Irradiation in Silicon Crystals

    NASA Astrophysics Data System (ADS)

    Yeritsyan, H. N.; Sahakyan, A. A.; Grigoryan, N. E.; Harutyunyan, V. V.; Tsakanov, V. M.; Grigoryan, B. A.; Yeremyan, A. S.; Amatuni, G. A.

    2016-10-01

    We present the results of a study on localized electronic centers formed in crystals by external influences (impurity introduction and irradiation). The main aim is to determine the nature of these centers in the forbidden gap of the energy states of the crystal lattice. For the case of semiconductors, silicon (Si) was applied as model material to determine the energy levels and concentration of radiation defects for application to both doped and other materials. This method relies on solving the appropriate equation describing the variation of the charge carrier concentration as a function of temperature n(T) for silicon crystals with two different energy levels and for a large set of N 1, N 2 (concentrations of electronic centers at each level), and n values. A total of almost 500 such combinations were found. For silicon, energy level values of ɛ 1 = 0.22 eV and ɛ 2 = 0.34 eV were used for the forbidden gap (with corresponding slopes determined from experimental temperature-dependent Hall-effect measurements) and compared with photoconductivity spectra. Additionally, it was shown that, for particular correlations among N 1, N 2, and n, curve slopes of ɛ 1/2 = 0.11 eV, ɛ 2/2 = 0.17 eV, and α = 1/2(ɛ 1 + ɛ 2) = 0.28 eV also apply. Comparison between experimental results for irradiation of silicon crystals by 3.5-MeV energy electrons and Co60 γ-quanta revealed that the n(T) curve slopes do not always coincide with the actual energy levels (electronic centers).

  4. LNL irradiation facilities for radiation damage studies on electronic devices

    NASA Astrophysics Data System (ADS)

    Bisello, D.; Candelori, A.; Giubilato, P.; Mattiazzo, S.; Pantano, D.; Silvestrin, L.; Tessaro, M.; Wyss, J.

    2016-11-01

    In this paper we will review the wide range of irradiation facilities installed at the INFN Legnaro National Laboratories and routinely used for radiation damage studies on silicon detectors, electronic components and systems. The SIRAD irradiation facility, dedicated to Single Event Effect (SEE) and bulk damage studies, is installed at the 14MV Tandem XTU accelerator and can deliver ion beams from H up to Au in the energy range from 28MeV to 300MeV. An Ion Electron Emission Microscope, also installed at SIRAD, allows SEE testing with micrometric sensitivity. For total dose tests, two facilities are presently available: an X-rays source and a 60Co γ -ray source. The 7MV Van de Graaff CN accelerator provides 1H beams in the energy range 2-7MeV and currents up to few μA for both total dose and bulk damage studies. At this facility, very high dose rates (up to ˜ 100 krad/s (SiO2)) can be achieved. Finally, also neutron beams are available, produced at the CN accelerator, by the reaction d + Be ⇒ n + B.

  5. Effects of electron beam irradiation on polyamide 12 with fiberglass reinforcement

    SciTech Connect

    Jeun, Joon-Pyo; Shin, Bum-Sik; Kim, Hyun-Bin; Nho, Young-Chang; Kang, Phil-Hyun

    2010-06-02

    In the present study, the effects of electron beam irradiation of polyamide 12 (PA12) with fiberglass reinforcement on the thermal and wear properties were investigated. Electron beam irradiation of PA 12 was carried out over a range of irradiation doses (100-600 kGy) in air. The gel formation in the presence of a curing agent was dependent on the radiation doses. The thermal properties of irradiated PA 12 were studied in the temperature region 50-250 deg. C to observe the changes in the melting point with radiation dose. The dimensional stability was significantly increased by electron beam irradiation and the related crosslinking of the PA 12.

  6. The Irradiation Effect of a Simultaneous Laser and Electron Dual-beam on Void Formation

    PubMed Central

    Yang, Zhanbing; Watanabe, Seiichi; Kato, Takahiko

    2013-01-01

    Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the striking effects of simultaneous laser-electron (photon-electron) dual-beam irradiation on void formation. Our results reveal that during laser-electron sequential irradiation, pre-laser irradiation enhanced void nucleation and subsequent electron irradiation enhanced void growth. However, the laser-electron dual-beam irradiation was analyzed to depress void swelling remarkably because the recombination of SVs and interstitials was enhanced. The results provide insight into the mechanism underlying the dual-beam radiation-induced depression of void swelling in solids. PMID:23383371

  7. The irradiation effect of a simultaneous laser and electron dual-beam on void formation.

    PubMed

    Yang, Zhanbing; Watanabe, Seiichi; Kato, Takahiko

    2013-01-01

    Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the striking effects of simultaneous laser-electron (photon-electron) dual-beam irradiation on void formation. Our results reveal that during laser-electron sequential irradiation, pre-laser irradiation enhanced void nucleation and subsequent electron irradiation enhanced void growth. However, the laser-electron dual-beam irradiation was analyzed to depress void swelling remarkably because the recombination of SVs and interstitials was enhanced. The results provide insight into the mechanism underlying the dual-beam radiation-induced depression of void swelling in solids.

  8. Electron irradiation-induced destruction of carbon nanotubes in electron microscopes.

    PubMed

    Mølhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Casper Hyttel; Horsewell, Andy; Bøggild, Peter

    2007-12-01

    Observations of carbon nanotubes under exposure to electron beam irradiation in standard transmission electron microscope (TEM) and scanning electron microscope (SEM) systems show that such treatment in some cases can cause severe damage of the nanotube structure, even at electron energies far below the approximate 100 keV threshold for knock-on damage displacing carbon atoms in the graphene structure. We find that the damage we observe in one TEM can be avoided by use of a cold finger. This and the morphology of the damage imply that water vapour, which is present as a background gas in many vacuum chambers, can damage the nanotube structure through electron beam-induced chemical reactions. Though, the dependence on the background gas makes these observations specific for the presently used systems, the results demonstrate the importance of careful assessment of the level of subtle structural damage that the individual electron microscope system can do to nanostructures during standard use. PMID:17445986

  9. Food Irradiation Using Electron Beams and X-Rays

    NASA Astrophysics Data System (ADS)

    Miller, Bruce

    2003-04-01

    In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh and frozen meat products, seafood, and eggs. With special regard to food safety, bacteria such as Salmonella enteridis, Listeria monocytogenes, Campylobacter jejuni and Escherichia coli serotype O157:H7 are the primary causes of food poisoning in industrialized countries. Ionizing doses in the range of only 1-5 kilogray (kGy) can virtually eliminate these organisms from food, without affecting the food's sensory and nutritional qualities, and without inducing radioactivity. The key elements of an accelerator-based irradiation facility include the accelerator system, a scanning system, and a material handling system that moves the product through the beam in a precisely controlled manner. Extensive radiation shielding is necessary to reduce the external dose to acceptable levels, and a safety system is necessary to prevent accidental exposure of personnel during accelerator operation. Parameters that affect the dose distribution must be continuously monitored and controlled with process control software. The choice of electron beam vs x-ray depends on the areal density (density times thickness) of the product and the anticipated mass throughput. To eliminate nuclear activation concerns, the maximum kinetic energy of the accelerator is limited by regulation to 10 MeV for electron beams, and 5 MeV for x-rays. From penetration considerations, the largest areal density that can be treated by double-sided electron irradiation at 10 MeV is about 8.8 g/cm2. Products having greater areal densities must be processed using more penetrating x-rays. The

  10. Electron stimulated desorption of anionic fragments from films of pure and electron-irradiated thiophene

    SciTech Connect

    Hedhili, M. N.; Cloutier, P.; Bass, A. D.; Madey, T. E.; Sanche, L.

    2006-09-07

    The electron stimulated desorption (ESD) of anions is used to explore the effects of electron irradiation on a thiophene film and we report measurements for electron impact on multilayer thiophene condensed on a polycrystalline platinum substrate. Below 22 eV and at low electron dose, desorbed anions include H{sup -} (the dominant signal) as well as S{sup -}, CH{sub 2}{sup -}, SH{sup -} and SCH{sub 2}{sup -}. Yield functions show that anions are desorbed both by dissociative electron attachment (DEA) with resonances observed at 9.5, 11, and 16 eV, and for energies >13 eV, by dipolar dissociation (DD). An increase in the S{sup -} signal from electron irradiated (beam-damaged) thiophene films and the appearance of a new DEA resonance in the S{sup -} yield function at 6 eV are linked to rupture of the thiophene ring and the formation of sulfur-terminated products within the film. The threshold energy for ring rupture is 5 eV. The desorption of new anions such as C{sub 4}H{sub 3}S{sup -} (Thiophene-H){sup -}is also observed from electron irradiated films and these likely arise from the decomposition of large radiation product molecules synthesized in the film. The yield functions of H{sup -}, S{sup -}, SH{sup -}, (Thiophene-H){sup -}, and (Thiophene+H){sup -} anions from irradiated thiophene films that have been annealed to 300 K, each exhibit a single resonant feature centered around 5.1 eV, suggesting that all signals derive from DEA to the same molecular radiation product. In contrast, only H{sup -} and S{sup -} are observed to desorb from films of 2-2-bithiophene and no resonance is seen below {approx}10 eV in the anion yield functions. These data suggest that electron irradiation causes formation of ring-opened oligomers, and that closed-ring or 'classical' oligomers, (similar to bithiophene) if formed, contribute little to the ESD of anions.

  11. Issues for Bringing Electron Beam Irradiators On-Line

    SciTech Connect

    Kaye, R.J.; Turman, B.N.

    1999-04-20

    Irradiation of red meat and poultry has been approved by the U.S. FDA, and the U.S. Department of Agriculture's rule for processing red meat is out for comment. Looking beyond the current issues of packaging materials, labeling, and consumer acceptance, this paper reviews the next step of implementation and how to remove, or at least reduce, the barriers to utilization. Polls of the user community identified their requirements for electron beam or x-ray processing of meat or poultry and their concerns about implementation for on-line processing. These needs and issues are compared to the capabilities of the accelerator industry. The critical issues of beam utilization and dose uniformity, factors affecting floor space requirements, and treatment costs are examined.

  12. A technique for pediatric total skin electron irradiation

    PubMed Central

    2012-01-01

    Background Total skin electron irradiation (TSEI) is a special radiotherapy technique which has generally been used for treating adult patients with mycosis fungoides. Recently, two infants presented with leukemia cutis isolated to the skin requiring TSEI. This work discusses the commissioning and quality assurance (QA) methods for implementing a modified Stanford technique using a rotating harness system to position sedated pediatric patients treated with electrons to the total skin. Methods and Results Commissioning of pediatric TSEI consisted of absolute calibration, measurement of dosimetric parameters, and subsequent verification in a pediatric patient sized cylindrical phantom using radiographic film and optically stimulated luminance (OSL) dosimeters. The depth of dose penetration under TSEI treatment condition was evaluated using radiographic film sandwiched in the phantom and demonstrated a 2 cm penetration depth with the maximum dose located at the phantom surface. Dosimetry measurements on the cylindrical phantom and in-vivo measurements from the patients suggested that, the factor relating the skin and calibration point doses (i.e., the B-factor) was larger for the pediatric TSEI treatments as compared to adult TSEI treatments. Custom made equipment, including a rotating plate and harness, was fabricated and added to a standard total body irradiation stand and tested to facilitate patient setup under sedated condition. A pediatric TSEI QA program, consisting of daily output, energy, flatness, and symmetry measurements as well as in-vivo dosimetry verification for the first cycle was developed. With a long interval between pediatric TSEI cases, absolute dosimetry was also repeated as part of the QA program. In-vivo dosimetry for the first two infants showed that a dose of ± 10% of the prescription dose can be achieved over the entire patient body. Conclusion Though pediatric leukemia cutis and the subsequent need for TSEI are rare, the ability to

  13. First demonstration of a free-electron laser driven by electrons from a laser irradiated photocathode

    NASA Astrophysics Data System (ADS)

    Curtin, Mark; Bennett, Glenn; Burke, Robert; Benson, Stephen; Madey, J. M. J.

    Results are reported from the first observation of a free-electron laser (FEL) driven by an electron beam from a laser-irradiated photocathode. The Rocketdyne/Stanford FEL achieved sustained oscillations lasting over three hours and driven by photoelectrons accelerated by the Stanford Mark III radio-frequency linac. A LaB6 cathode, irradiated by a tripled Nd:YAG mode-locked drive laser, is the source of the photoelectrons. The drive laser, operating at 95.2 MHz, is phase-locked to the 30th subharmonic of the S-band linac. Peak currents in excess of 125 amps are observed and delivered to the Rocketdyne two-meter undulator, which is operated as a stand-alone oscillator. The electron beam has an energy spread of 0.8 percent (FWHM) at 38.5 MeV and an emittance, at the undulator, comparable to that observed for thermionic operation of the electron source. Small signal gain in excess of 150 percent is observed. Preliminary estimates of the electron beam brightness deliverable to the undulator range from 3.5 to 5.0 x 10 to the 11 amps/sq m.

  14. Microbial growth and sensory quality of dried potato slices irradiated by electrons

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Song, Hyeon-Jeong; Song, Kyung-Bin

    2011-06-01

    Electron beam irradiation was applied to secure the microbial safety of dried purple sweet potato. After purple sweet potato slices had been dehydrated with 20% (w/w) maltodextrin solution, the samples were irradiated at doses 2, 4, 6, 8, and 10 kGy and then stored at 20 °C for 60 days. Microbiological data indicated that the populations of total aerobic bacteria and of yeast and molds significantly decreased with increase in irradiation dosage. Specifically, microbial load was reduced by about three log cycles at 6 kGy compared to those of the control. Based on the color measurement of the potato slices, electron beam irradiation treatment did not affect the color quality. Sensory evaluation results also showed that electron beam irradiation did not affect overall sensory scores during storage. These results suggest that electron beam irradiation could be useful for improving microbial safety without impairing the quality of the potato slices during storage.

  15. Equipment for Beam Current and Electron Energy Monitoring During Industry Irradiation.

    NASA Astrophysics Data System (ADS)

    Zavadtsev, A. A.

    1997-05-01

    The electron beam irradiation sterilization is placed first among all types of medical items sterilization. The quality of sterilization is determined by value of dose, which is in one's turn determined by beam current, electron energy and beam scanning system parameters. Therefore this parameters have to be controlled during the irradiation process. The equipment for beam current and electron energy monitoring allows to control beam current, electron energy spectrum and nominal deflection of electron beam when scanning during the irradiation process each scanning period or, for example, each tenth period by request.

  16. Molecular dynamics study of electron-irradiation effects in single-walled carbon nanotubes

    SciTech Connect

    Yasuda, Masaaki; Kimoto, Yoshihisa; Tada, Kazuhiro; Mori, Hideki; Akita, Seiji; Hirai, Yoshihiko; Nakayama, Yoshikazu

    2007-05-15

    Molecular dynamics studies are carried out to investigate electron-irradiation effects in single-walled carbon nanotubes. We have proposed a simulation model which includes the interaction between a high-energy incident electron and a carbon atom, based on Monte Carlo method using the elastic-scattering cross section. The atomic level behavior of a single-walled carbon nanotube under electron irradiation is demonstrated in nanosecond time scale. The incident electron energy, tube diameter, and tube temperature dependences of electron-irradiation effects are studied with the simulation.

  17. EMERGING TECHNOLOGY BULLETIN: REMOVAL OF PHENOL FROM AQUEOUS SOLUTIONS USING HIGH ENERGY ELECTRON BEAM IRRADIATION

    EPA Science Inventory

    Irradiation of aqueous solutions with high-energy electrons results in the formation of the aqueous electron, hydrogen radical, H-, and the hydroxyl radical, OH-. These reactive transient species initiate chemical reactions capable of destroying organic compounds in aqueous solut...

  18. Influence of electron irradiation on the structural and thermal properties of silk fibroin films

    SciTech Connect

    Asha, S.; Sangappa,; Sanjeev, Ganesh

    2015-06-24

    Radiation-induced changes in Bombyx mori silk fibroin (SF) films under electron irradiation were investigated and correlated with dose. SF films were irradiated in air at room temperature using 8 MeV electron beam in the range 0-150 kGy. Various properties of the irradiated SF films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Electron irradiation was found to induce changes in the physical and thermal properties, depending on the radiation dose.

  19. Low-temperature radiation cracking of heavy oil under continuous and pulse electron irradiation

    NASA Astrophysics Data System (ADS)

    Zaikin, Yuriy A.

    2016-05-01

    The dependence of the chain reaction parameters on the conditions of pulse and continuous electron irradiation is analyzed for the case of low-temperature radiation cracking of heavy oils. The specificity of kinetics and yields of light products after radiation cracking are considered in the cases of continuous and pulse irradiation. Theoretical calculations are compared with experimental data on electron irradiation of heavy oil in different conditions.

  20. Surface morphological, mechanical and thermal characterization of electron beam irradiated fibers

    NASA Astrophysics Data System (ADS)

    Choi, Hae Young; Han, Seong Ok; Lee, Jung Soon

    2008-12-01

    The surface morphology of henequen irradiated by electron beam has been investigated by atomic force microscopy (AFM). Also, the extents to which electron beam irradiation affected the tensile and thermal properties of henequen fiber were investigated with Instron tensile tests and thermogravimetric analysis (TGA). The AFM studies showed that the pectin, waxy and primary layers (P) of henequen fiber, which have heterogeneous structures, were removed from the fiber surface by electron beam irradiation. The tensile strength and thermal stability of henequen fiber decreased with increasing dose of electron beam. At the irradiation of 10 kGy, the surface roughness increased because of the removal of the pectin, waxy and P layer, but the tensile strength of henequen irradiated with 10 kGy were maintained. It has been suggested that the use of a 10 kGy dose of electron beam to modify the henequen fiber surface can improve the surface properties and preserve the fibers' mechanical and thermal properties.

  1. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Fan, Xue; Diao, Dongfeng

    2016-10-01

    We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp2 nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp2 nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp2 nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  2. The Effect of Low-Energy-Electron Irradiation to DNA Molecules

    NASA Astrophysics Data System (ADS)

    Hasimoto, Hideyuki; Mochiji, Kozo

    Secondary electrons with kinetic energies below 20 eV are abundant species generated in living cells by the irradiation with ionizing radiations. It is unclear whether such low-energy electrons are able to induce damage on DNA. In this study, we have directly observed the structural changes of DNA molecules under the irradiation with 4-40 eV electrons which are field-emitted from the tip of a scanning tunneling microscope. Single- and double-strand breaks of linear DNA molecules (λDNA and ΦX DNA) are induced by the electron irradiations. By the electron irradiations of circular DNA molecules (pUC18 DNA) in an entanglement, some parts of the DNA were lost or spread by the dissociation of the molecules. These electron-induced reactions are strongly dependent on the electron energies.

  3. Radiation-induced segregation and precipitation behaviours around cascade clusters under electron irradiation.

    PubMed

    Sueishi, Yuichiro; Sakaguchi, Norihito; Shibayama, Tamaki; Kinoshita, Hiroshi; Takahashi, Heishichiro

    2003-01-01

    We have investigated the formation of cascade clusters and structural changes in them by means of electron irradiation following ion irradiation in an austenitic stainless steel. Almost all of the cascade clusters, which were introduced by the ion irradiation, grew to form interstitial-type dislocation loops or vacancy-type stacking fault tetrahedra after electron irradiation at 623 K, whereas a few of the dot-type clusters remained in the matrix. It was possible to recognize the concentration of Ni and Si by radiation-induced segregation around the dot-type clusters. After electron irradiation at 773 K, we found that some cascade clusters became precipitates (delta-Ni2Si) due to radiation-induced precipitation. This suggests that the cascade clusters could directly become precipitation sites during irradiation.

  4. Bending of metal-filled carbon nanotube under electron beam irradiation

    SciTech Connect

    Misra, Abha

    2012-03-15

    Electron beam irradiation induced, bending of Iron filled, multiwalled carbon nanotubes is reported. Bending of both the carbon nanotube and the Iron contained within the core was achieved using two approaches with the aid of a high resolution electron microscope (HRTEM). In the first approach, bending of the nanotube structure results in response to the irradiation of a pristine kink defect site, while in the second approach, disordered sites induce bending by focusing the electron beam on the graphite walls. The HRTEM based in situ observations demonstrate the potential for using electron beam irradiation to investigate and manipulate the physical properties of confined nanoscale structures.

  5. Inactivation of Bacillus Endospores in Envelopes by Electron Beam Irradiation

    PubMed Central

    Helfinstine, Shannon L.; Vargas-Aburto, Carlos; Uribe, Roberto M.; Woolverton, Christopher J.

    2005-01-01

    The anthrax incidents in the United States in the fall of 2001 led to the use of electron beam (EB) processing to sanitize the mail for the U.S. Postal Service. This method of sanitization has prompted the need to further investigate the effect of EB irradiation on the destruction of Bacillus endospores. In this study, endospores of an anthrax surrogate, B. atrophaeus, were destroyed to demonstrate the efficacy of EB treatment of such biohazard spores. EB exposures were performed to determine (i) the inactivation of varying B. atrophaeus spore concentrations, (ii) a D10 value (dose required to reduce a population by 1 log10) for the B. atrophaeus spores, (iii) the effects of spore survival at the bottom of a standardized paper envelope stack, and (iv) the maximum temperature received by spores. A maximum temperature of 49.2°C was reached at a lethal dose of ∼40 kGy, which is a significantly lower temperature than that needed to kill spores by thermal effects alone. A D10 value of 1.53 kGy was determined for the species. A surface EB dose between 25 and 32 kGy produced the appropriate killing dose of EB between 11 and 16 kGy required to inactivate 8 log10 spores, when spore samples were placed at the bottom of a 5.5-cm stack of envelopes. PMID:16269738

  6. Electron irradiation experiments in support of fusion materials development

    SciTech Connect

    Gelles, D.S. ); Ohnuki, S.; Takahashi, H. ); Matsui, H. ); Kohno, Y. )

    1991-11-01

    Microstructural evolution in response to 1 MeV irradiation has been investigated for three simple ferritic alloys, pure beryllium, pure vanadium, and two simple vanadium alloys over a range of temperatures and doses. Microstructural evolution in Fe-3, -9, and -18Cr ferritic alloys is found to consist of crenulated, faulted a<100> loops and circular, unfaulted a/2 <111> loops at low temperatures, but with only unfaulted loops at high temperatures. The complex dislocation evolution is attributed to sigma phase precipifaults arising from chromium segregation to point defect sinks. Beryllium is found to be resistant to electron damage; the only effect observed was enhanced dislocation mobility. Pure vanadium, V-5Fe, and V-1Ni microstructural response was complicated by precipitation on heating to 400{degrees}C and above, but dislocation evolution was investigated in the range of room temperature to 300{degrees}C and at 600{degrees}C. The three materials behaved similarly, except that pure vanadium showed more rapid dislocation evolution. This difference does not explain the enhanced swelling observed in vanadium alloys.

  7. Low-temperature electron irradiation and annealing in pure magnesium

    SciTech Connect

    Simester, J.H.

    1982-01-01

    In this study of magnesium after 1.0 MeV electron irradiations at 1.55/sup 0/K, it has been observed that the damage production rate in Mg is (3.57 +- 0.03) x 10/sup -26/ ..cap omega..cm/(e/sup -/ cm/sup 2/). There is no evidence for thermal annealing up to 4/sup 0/K. The low temperature recovery in magnesium is found to consist of two broad substages between 4 to 14/sup 0/K, both of which exhibit evidence for correlated and uncorrelated recovery processes. The two substages are found to have very different frequency factors for annealing, and there is evidence that the recovery processes in the second substage are influenced by those in the first. A model for recovery is proposed using the split configuration in the plane which explains the first substage as being due to interstitial migration in the basal plane and the second to migration perpendicular to the plane.

  8. Study of electrical properties of silica glasses, intended for FED spacers, under electron irradiation

    NASA Astrophysics Data System (ADS)

    Fakhfakh, S.; Jbara, O.; Belhaj, M.; Rondot, S.; Mouze, D.; Fakhfakh, Z.

    2008-11-01

    The charge properties, under electron irradiation, of three types of glasses are studied by employing scanning electron microscope (SEM) associated with the technique called the electrostatic influence method. The experimental conditions are closed to those of typical field emission display (FED) operation. To determine the amount of trapped charges during and after electron irradiation, a special arrangement adapted to the SEM was used. This arrangement allows displacement and leakage currents to be simultaneously measured. The secondary electron emission yield during electron irradiation is also deduced. The trapping ability of each glass is analyzed taking into account the regulation mechanisms involved under electron irradiation. Finally useful indications permitting an adequate selection of glasses that may be used as FED spacers are deduced.

  9. Detection of prior irradiation of dried fruits by electron spin resonance (ESR)

    NASA Astrophysics Data System (ADS)

    Esteves, M. P.; Andrade, M. E.; Empis, J.

    1999-08-01

    Dried almonds, raisins, dates and pistachio were irradiated using either gamma radiation or electron beam, at an average absorbed dose of 5 kGy. To detect the previous irradiation different parts of the dried fruits were analyzed by ESR spectroscopy: almonds: skin; raisins: dried pulp; dates: dried pulp and stone; pistachio: nutshell. Analyses were carried out 2-3 months and 6 months after irradiation. A series of signals tentatively described as "cellulose-like", "sugar-like" and "complex" radical were observed, and some slight differences between spectra from samples irradiated with gamma rays and electrons were evident.

  10. Electron spin resonance studies of some irradiated pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Gibella, M.; Crucq, A.-S.; Tilquin, B.; Stocker, P.; Lesgards, G.; Raffi, J.

    2000-03-01

    Five antibiotics belonging to the cephalosporins and penicillins groups have been irradiated: anhydrous ampicilline acid, amoxicilline acid trihydrate, cefuroxime sodium salt, cloxacilline sodium salt monohydrate and ceftazidime pentahydrate. ESR studies have been carried out, showing the influence of irradiation and storage parameters on the nature and concentration of the free radicals trapped. These results may be used to detect an irradiation treatment on such pharmaceuticals.

  11. Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

    NASA Astrophysics Data System (ADS)

    Lucero, J. F.; Rojas, J. I.

    2016-07-01

    Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient's entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

  12. 78 FR 27303 - Irradiation in the Production, Processing, and Handling of Animal Feed and Pet Food; Electron...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-10

    ... Feed and Pet Food; Electron Beam and X-Ray Sources for Irradiation of Poultry Feed and Poultry Feed... safe use of electron beam and x-ray sources for irradiation of poultry feed and poultry feed... CFR part 579) to provide for the safe use of electron beam and x-ray sources for irradiation...

  13. Effect of electron beam irradiation sterilization on the biomedical poly (octene-co-ethylene)/polypropylene films

    NASA Astrophysics Data System (ADS)

    Luan, Shifang; Shi, Hengchong; Yao, Zhanhai; Wang, Jianwei; Song, Yongxian; Yin, Jinghua

    2010-05-01

    The effect of electron beam irradiation with the dose ranging from 15 to 40 kGy on poly (octene-co-ethylene) (POE)/polypropylene (PP) films was investigated. Wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), yellowness index testing and mechanical performance measurement were applied to characterize the films. It demonstrated that crystalline structure exhibited little change, and degree of crystallinity slightly change under the irradiation treatment. Irradiation brought about oxidation of the films, forming hydroxyl groups of the peroxides and carbonyl groups. Tensile properties become worse as irradiation dose increased. Electron beam irradiation with the dose of 15-40 kGy has little effect on crystalline performance and a little influence for the POE/PP films, indicating a good irradiation resistance.

  14. Thermal annealing of GaAs concentrator solar cells. [during electron irradiation

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.; Brinker, D. J.

    1989-01-01

    The thermal annealing of GaAs concentrator cells after electron irradiation is reported. Results are given for cells annealed at 150, 200, and 250 C. Isochronal annealing was done for 20 min intervals up to 350 C. For cells irradiated with electrons of energies between 0.7 and 2.3 MeV, the recovery decreases with increasing electron energy. Isothermal and isochronal annealing produce the same recovery. Cells irradiated to 3 x 10 to the 15th or 1 x 10 to the 16th e/sq cm recover to similar unannealed fractions. Significant annealing is seen starting at 150 C, although very long times are required.

  15. Triacylglycerols profiling as a chemical tool to identify mushrooms submitted to gamma or electron beam irradiation.

    PubMed

    Fernandes, Ângela; Barreira, João C M; Antonio, Amilcar L; Martins, Anabela; Ferreira, Isabel C F R; Oliveira, M Beatriz P P

    2014-09-15

    In order to define irradiation treatment as a routine conservation methodology, it is imperative to develop chemometric indicators with the ability to distinguish irradiated from unirradiated foodstuffs. Electron spin resonance, photostimulated luminescence and thermoluminescence methods were employed to monitor radiation-induced markers, as well as different chemical compounds produced from the lipidic fraction of different foodstuffs. Apart from these methods, the specificity of triacylglycerol profiles has previously been detected in mushroom species, as has the effect of irradiation treatment in the triacylglycerol profiles of chestnut. Accordingly, the feasibility of using this as a chemometric indicator of irradiated mushrooms was evaluated. In line with the obtained results in literature, the effects of each type of irradiation were significantly different, as can be concluded from the correlations among discriminant functions and variables within each statistical test. Triacylglycerol profiling proved to be a useful tool to detect irradiated mushrooms, independently of the species or irradiation source, especially for doses above 1 kGy.

  16. Electrical Characterization of High Energy Electron Irradiated Ni/4 H-SiC Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Paradzah, A. T.; Omotoso, E.; Legodi, M. J.; Auret, F. D.; Meyer, W. E.; Diale, M.

    2016-08-01

    The effect of high energy electron irradiation on Ni/4 H-SiC Schottky barrier diodes was evaluated by current-voltage ( I- V) and capacitance-voltage ( C- V) measurements at room temperature. Electron irradiation was achieved by using a radioactive strontium source with peak emission energy of 2.3 MeV. Irradiation was performed in fluence steps of 4.9 × 1013 cm-2 until a total fluence of 5.4 × 1014 cm-2 was reached. The Schottky barrier height determined from I- V measurements was not significantly changed by irradiation while that obtained from C- V measurements increased with irradiation. The ideality factor was obtained before irradiation as 1.05 and this value did not significantly change as a result of irradiation. The series resistance increased from 47 Ω before irradiation to 74 Ω after a total electron fluence of 5.4 × 1014 cm-2. The net donor concentration decreased with increasing irradiation fluence from 4.6 × 1014 cm-3 to 3.0 × 1014 cm-3 from which the carrier removal rate was calculated to be 0.37 cm-1.

  17. Crystallization of sputter-deposited amorphous Ge films by electron irradiation: Effect of low-flux pre-irradiation

    NASA Astrophysics Data System (ADS)

    Okugawa, M.; Nakamura, R.; Ishimaru, M.; Yasuda, H.; Numakura, H.

    2016-10-01

    We investigated the effect of low-flux electron irradiation with 125 keV to sputter-deposited amorphous germanium on the amorphous structure and electron-induced crystallization microstructure by TEM following our previous study on the effect of aging at room temperature. In samples aged for 3 days, coarse, spherical particles about 100 nm in diameter appear dominantly. By low-flux pre-irradiation to the samples, a reduction in the size and number of coarse particles, embedded in the matrix with fine nanograins of the diamond cubic structure, was noted with the increase in fluence. The crystal structure of these coarse particles was found to be not cubic but hexagonal. In samples aged for 4 months, a similar tendency was observed. In samples aged for 7 months, on the other hand, the homogeneous diamond cubic structured nanograins were unchanged by pre-irradiation. These results indicate that pre-irradiation as well as aging modifies the amorphous structure, preventing the appearance of a hexagonal phase. The elimination of a certain amount of medium-range ordered clusters by pre-irradiation, included in as-deposited samples and the samples aged for 4 months, apparently gives rise to a reduction in the size and number of coarse particles with a metastable hexagonal structure.

  18. Hydrolytic degradation of electron beam irradiated high molecular weight and non-irradiated moderate molecular weight PLLA.

    PubMed

    Loo, Say Chye Joachim; Tan, Hui Tong; Ooi, Chui Ping; Boey, Yin Chiang Freddy

    2006-05-01

    The purpose of this study is to examine the hydrolytic degradation of electron beam irradiated ring-opening polymerized (ROP) poly(l-lactide) (PLLA-ir) and non-irradiated melt polycondensation polymerized poly(l-lactic acid) (PLLA-pc). It was observed that irradiation increases the hydrolytic degradation rate constant for ROP PLLA. This was due to a more hydrophilic PLLA-ir, as a result of irradiation. The degradation rate constants (k) of PLLA-ir samples were also found to be similar, regardless of the radiation dose, and an empirically formulated equation relating hydrolytic degradation time span to radiation dose was derived. The k value for PLLA-pc was observed to be lower than that for PLLA-ir, though the latter had a higher molecular weight. This was due to the difference in degradation mechanism, in which PLLA-ir undergoes end group scission, through a back- biting mechanism, during hydrolysis and thus a faster hydrolysis rate. Electron beam irradiation, though accelerates the degradation of PLLA, has been shown to be useful in accurately controlling the hydrolytic time span of PLLA. This method of controlling the hydrolytic degradation time was by far an easier task than through melt polycondensation polymerization. This would allow PLLA to be used for drug delivery purposes or as a temporary implant that requires a moderate time span (3-6 months). PMID:16701888

  19. Effects of electron beam irradiation on binary polyamide-6 blends with metallocene copolymers

    NASA Astrophysics Data System (ADS)

    Rosales, C.; López-Quintana, S.; Gobernado-Mitre, I.; Merino, J. C.; Pastor, J. M.

    2007-12-01

    The effect of electron beam irradiation on thermal and mechanical properties, and SEM morphology of polyamide-6 (PA-6) blends with grafted copolymers was investigated. High toughness materials were obtained with ethylene-polypropylene-diene grafted copolymers without significant variations in their thermal properties and Izod impact strength at room temperature and -30 °C with the irradiation doses used.

  20. Cyclization and crosslinking of polybutadiene in solution by electron beam irradiation

    SciTech Connect

    Hayashi, K.; Tachibana, M.; Okamura, S.

    1980-09-01

    Effects of electron beam irradiation on liquid polybutadiene in n-hexane solution were studied at -10/sup 0/C. With irradiation, crosslinking of the polymer and loss of double bond by cyclization took place at the same time. These reactions were retarded by the addition of DPPH or triethylamine which indicated that both radical and cationic mechanisms contributed to this system.

  1. Rapid Annealing of Cu-In-Ga-Se Precursors by Electron Beam Irradiation Method.

    PubMed

    Lim, Seonkyoung; Kim, Young-Man; Jeong, Chaehwan

    2016-05-01

    Cu-In-Ga-Se precursors were prepared by RF- and DC-sputtering methods and then irradiated with an in-situ electron beam irradiation unit. Ternary (In,Ga)Se2 and binary CuSe targets were simultaneously used for preparation of precursors. The electron dose and irradiation time were kept constant at 300 seconds and 200 W of RF power, respectively, while intensities of accelerated electrons were varied from 2.5 to 4.5 keV. The thickness of all e-beam irradiated CuInGaSe2 (CIGS) films decreased from 1,250 nm to 470 nm. The crystalline properties of e-beam irradiated CIGS films were clearly shown on all samples and the highest intensity of (112) peak at 3.5 keV. The compositional ratio of Cu/(In + Ga) in the e-beam sample irradiated at 3.5 keV was coincident with that of the precursors. The degree of Ga content on the depth of the e-beam sample irradiated at 3.5 keV was uniformly distributed between the TCO/CdS layer and Mo back contact. Electron beam irradiation onto Cu-In-Ga-Se precursors as a rapid annealing method could be an excellent candidate for crystallization to the Cu(In,Ga)Se2 films.

  2. Rapid Annealing of Cu-In-Ga-Se Precursors by Electron Beam Irradiation Method.

    PubMed

    Lim, Seonkyoung; Kim, Young-Man; Jeong, Chaehwan

    2016-05-01

    Cu-In-Ga-Se precursors were prepared by RF- and DC-sputtering methods and then irradiated with an in-situ electron beam irradiation unit. Ternary (In,Ga)Se2 and binary CuSe targets were simultaneously used for preparation of precursors. The electron dose and irradiation time were kept constant at 300 seconds and 200 W of RF power, respectively, while intensities of accelerated electrons were varied from 2.5 to 4.5 keV. The thickness of all e-beam irradiated CuInGaSe2 (CIGS) films decreased from 1,250 nm to 470 nm. The crystalline properties of e-beam irradiated CIGS films were clearly shown on all samples and the highest intensity of (112) peak at 3.5 keV. The compositional ratio of Cu/(In + Ga) in the e-beam sample irradiated at 3.5 keV was coincident with that of the precursors. The degree of Ga content on the depth of the e-beam sample irradiated at 3.5 keV was uniformly distributed between the TCO/CdS layer and Mo back contact. Electron beam irradiation onto Cu-In-Ga-Se precursors as a rapid annealing method could be an excellent candidate for crystallization to the Cu(In,Ga)Se2 films. PMID:27483884

  3. Hardening and microstructural evolution in A533B steels under neutron irradiation and a direct comparison with electron irradiation

    NASA Astrophysics Data System (ADS)

    Fujii, K.; Nakata, H.; Fukuya, K.; Ohkubo, T.; Hono, K.; Nagai, Y.; Hasegawa, M.; Yoshiie, T.

    2010-05-01

    A533B steels irradiated at 290 °C up to 10 mdpa in the Kyoto University Reactor were examined by hardness, positron annihilation and atom probe measurements. Dose dependent irradiation hardening and formation of Cu-rich clusters were confirmed in medium Cu (0.12% and 0.16%Cu) steels whereas neither hardening nor cluster formation was detected in low Cu (0.03%Cu) steel. No microvoids were formed in any of the steels. Post-irradiation annealing in medium Cu steels revealed that the hardening recovery at temperatures above 350-400 °C could be attributed to compositional changes and dissociation of the Cu-rich clusters. Compared to electron irradiation at almost the same dose and dose rate, KUR irradiation caused almost the same hardening and produced Cu-rich clusters, more solute-enriched with larger size and lower density. Considering lower production of freely-migrating vacancies in neutron irradiation, the results suggested that cascades enhance the formation of Cu-rich clusters.

  4. Electrical properties of irradiated PVA film by using ion/electron beam

    NASA Astrophysics Data System (ADS)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant ɛ ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  5. Nonlocal electron transport in the presence of high-intensity laser irradiation

    SciTech Connect

    Epperlein, E.M.; Short, R.W. )

    1994-08-01

    We investigate electron transport in a plasma heated by spatially modulated laser irradiation. When the heating rate is greater than the electron-electron collision rate, the thermal conductivity is reduced by a factor of 3 to 4 from the Spitzer-Haerm [Phys. Rev. 89, 977 (1953)] value for [ital K][lambda][sub [ital e

  6. Correlation between electron-irradiation defects and applied stress in graphene: A molecular dynamics study

    SciTech Connect

    Kida, Shogo; Yamamoto, Masaya; Kawata, Hiroaki; Hirai, Yoshihiko; Yasuda, Masaaki; Tada, Kazuhiro

    2015-09-15

    Molecular dynamics (MD) simulations are performed to study the correlation between electron irradiation defects and applied stress in graphene. The electron irradiation effect is introduced by the binary collision model in the MD simulation. By applying a tensile stress to graphene, the number of adatom-vacancy (AV) and Stone–Wales (SW) defects increase under electron irradiation, while the number of single-vacancy defects is not noticeably affected by the applied stress. Both the activation and formation energies of an AV defect and the activation energy of an SW defect decrease when a tensile stress is applied to graphene. Applying tensile stress also relaxes the compression stress associated with SW defect formation. These effects induced by the applied stress cause the increase in AV and SW defect formation under electron irradiation.

  7. The GfW handbook for data compilation of irradiation tested electronic components, volume 3

    NASA Astrophysics Data System (ADS)

    Wulf, F.; Braeunig, D.; Boden, A.

    1984-05-01

    Fifty-three standardized reports of spacecraft electronic components irradiation tests are presented. Statistical values are given which enable reader to evaluate the components life time in a radiative environment.

  8. Morphological and structural modifications of multiwalled carbon nanotubes by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, N. G.; Makunin, A. V.; Motaweh, H. A.

    2016-10-01

    Effects of electron beam irradiation on a morphology and structure of multiwalled carbon nanotubes sample in a normal imaging regime of a scanning electron microscope (SEM) were investigated. Direct SEM observations give evidence that irradiation by electron beam in SEM eliminates morphological unevenness, in the form of round spots of white contrast, on the surface of carbon nanotubes (CNTs) and makes the tubes thinner. Electron dispersive analysis and Raman spectroscopy are used to explore the origin and nature of these spots. From this analysis we found that e-beam irradiation improves the CNTs graphitization. The synergy of thermal heating and ionization produced by the irradiation are discussed as possible mechanisms of the observed effects.

  9. Secondary electron yield of Cu technical surfaces: Dependence on electron irradiation

    NASA Astrophysics Data System (ADS)

    Larciprete, R.; Grosso, D. R.; Commisso, M.; Flammini, R.; Cimino, R.

    2013-01-01

    The secondary emission yield (SEY) properties of colaminated Cu samples for LHC beam screens are correlated to the surface chemical composition determined by x-ray photoelectron spectroscopy. The surface of the as-received samples is characterized by the presence of significant quantities of contaminating adsorbates and by the maximum of the SEY curve (δmax⁡) being as high as 2.1. After extended electron scrubbing at kinetic energy of 10 and 500 eV, the δmax⁡ value drops to the ultimate values of 1.35 and 1.1, respectively. In both cases the surface oxidized phases are significantly reduced, whereas only in the sample scrubbed at 500 eV the formation of a graphitic-like C layer is observed. We find that the electron scrubbing of technical Cu surfaces can be described as occurring in two steps: the first step consists in the electron-induced desorption of weakly bound contaminants that occurs indifferently at 10 and at 500 eV and corresponds to a partial decrease of δmax⁡; the second step, activated by more energetic electrons and becoming evident at high doses, increases the number of graphitic-like C-C bonds via the dissociation of adsorbates already contaminating the as-received surface or accumulating on this surface during irradiation. Our results demonstrate how the kinetic energy of impinging electrons is a crucial parameter when conditioning the surfaces of Cu and other metals by means of electron-induced chemical processing.

  10. Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions

    NASA Astrophysics Data System (ADS)

    Medvedev, N.; Volkov, A. E.; Ziaja, B.

    2015-12-01

    In this brief review we discuss the transient processes in solids under irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and swift-heavy ions (SHI). Both kinds of irradiation produce highly excited electrons in a target on extremely short timescales. Transfer of the excess electronic energy into the lattice may lead to observable target modifications such as phase transitions and damage formation. Transient kinetics of material excitation and relaxation under FEL or SHI irradiation are comparatively discussed. The same origin for the electronic and atomic relaxation in both cases is demonstrated. Differences in these kinetics introduced by the geometrical effects (μm-size of a laser spot vs nm-size of an ion track) and initial irradiation (photoabsorption vs an ion impact) are analyzed. The basic mechanisms of electron transport and electron-lattice coupling are addressed. Appropriate models and their limitations are presented. Possibilities of thermal and nonthermal melting of materials under FEL and SHI irradiation are discussed.

  11. Effects of Electron Beam and Microwave Irradiation on Human Blood Proteins

    SciTech Connect

    Martin, Diana I.; Craciun, Gabriela D.; Manaila, Elena N.; Ighigeanu, Daniel I.; Iacob, Nicusor I.; Oproiu, Constantin V.; Stan, Dana E.; Radu, Roxana R.; Margaritescu, Irina D.; Chirita, Doru I.

    2007-04-23

    The effects of separated and combined accelerated electron beam (EB) of 6.23 MeV and microwave (MW) of 2.45GHz irradiation on proteins in samples of human serum, human plasma and human integral blood are presented. Also, it was studied the effect of separate and combined EB and MW irradiation on proteins irradiated in samples of human integral blood, without and in the presence of a synthetic compound solution (S.C.S.) which is expected to exhibit various biological actions, such as to diminish or to increase the irradiation effects.

  12. Effects of high-energy electron irradiation of chicken meat on Salmonella and aerobic plate count

    SciTech Connect

    Heath, J.L.; Owens, S.L.; Tesch, S.; Hannah, K.W. )

    1990-01-01

    Four experiments were used to determine the effects of high-energy irradiation on the number of aerobic microorganisms and Salmonella on broiler breasts and thighs. Irradiation ranging from 100 to 700 kilorads (krads) was provided by a commercial-scale, electron-beam accelerator. Irradiation of broiler breast and thigh pieces with electron beams at levels of 100, 200, 300, 400, 500, and 600 krads showed that levels as low as 100 krads would eliminate Salmonella. When 33 thighs were tested after irradiation at 200 krads, only one thigh tested presumptive positive. The total number of aerobic organisms was reduced by 2 to 3 log10 cycles at irradiation levels of 100, 200, 300, 400, 500, 600, and 700 krads. Increasing the dose above 100 krads gave little if any additional benefit.

  13. The EB10 10 MeV, 30 kW electron irradiation facility

    NASA Astrophysics Data System (ADS)

    Karlsson, Mikael

    An irradiation plant including a 10 MeV, 30 kW electron accelerator is described. The accelerator is a four stage linac of standing wave type. Using a 90 degrees bending magnet for energy definition it irradiates boxes on a conveyor from below. The system design emphasizes the necessity for documentation of absorbed dose for each irradiated box by continuous monitoring and recording of the beam process parameters. This makes the system well suitable for irradiation sterilization. A magnet at the exit window corrects for the divergent field introduced by the scanning magnet, giving vertical electrons over the full scanning width. This feature provides more uniform irradiation and it also increases the efficiency of the unit by almost 20 %.

  14. Analysis of electron spin resonance spectra of irradiated gingers: Organic radical components derived from carbohydrates

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2010-04-01

    Electron spin resonance (ESR) spectral characterizations of gingers irradiated with electron beam were studied. Complex asymmetrical spectra (near g=2.005) with major spectral components (line width=2.4 mT) and minor signals (at 6 mT apart) were observed in irradiated gingers. The spectral intensity decreased considerably 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of characteristics of free radical components derived from carbohydrates in gingers are in good agreement with the observed spectra. Analysis showed that shortly after irradiation the major radical components of gingers were composed of radical species derived from amylose and cellulose, and the amylose radicals subsequently decreased considerably. At 30 days after irradiation, the major radical components of gingers were composed of radical species derived from cellulose, glucose, fructose or sucrose.

  15. Application of electron-beam irradiation combined with antioxidants for fermented sausage and its quality characteristic

    NASA Astrophysics Data System (ADS)

    Lim, D. G.; Seol, K. H.; Jeon, H. J.; Jo, C.; Lee, M.

    2008-06-01

    The effects of various doses of electron-beam irradiation on the changes in microbiological attributes of fermented sausage and the combined effect of electron-beam irradiation and various antioxidants on the oxidative stability and sensory properties during cold storage were investigated. Results indicated that 2 kGy of irradiation was the most effective in manufacturing a fermented sausage, and the addition of rosemary extracts was effective in controlling the production of off-flavor and development of lipid oxidation during cold storage.

  16. Free Volume Related Fluorescence Properties of Electron Irradiated Chalcone Doped PMMA Films

    SciTech Connect

    Ravindrachary, Ismayil V.; Bhajantri, R. F.; Harisha, A.; Praveena, S. D.

    2011-07-15

    Effect of electron irradiation on free volume related fluorescence properties of chalcone doped Poly(methyl methacrylate)(PMMA) composite films have been studied using Positron Annihilation and Fluorescence spectroscopic techniques. In this polymer composite, enhancement of fluorescence at lower doses and reduction at higher doses has been observed under electron irradiation. From Positron annihilation studies suggests that at lower doses of irradiation induced crosslinking which affect the free volume properties and inturn hinders the chalcone molecular rotation. At higher doses chain scission process affect matrix relaxation. Under the restricted condition the chromophore molecules likely to emit enhanced fluorescence and its mobility is directly related to the free volume around it.

  17. Concurrent in situ ion irradiation transmission electron microscope

    SciTech Connect

    Hattar, K.; Bufford, D. C.; Buller, D. L.

    2014-08-29

    An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

  18. Space charge limited electron emission from a Cu surface under ultrashort pulsed laser irradiation

    SciTech Connect

    Wendelen, W.; Autrique, D.; Bogaerts, A.

    2010-10-08

    In this theoretical study, the electron emission from a copper surface under ultrashort pulsed laser irradiation is investigated using a one dimensional particle in cell model. Thermionic emission as well as multi-photon photoelectron emission were taken into account. The emitted electrons create a negative space charge above the target, consequently the generated electric field reduces the electron emission by several orders of magnitude. The simulations indicate that the space charge effect should be considered when investigating electron emission related phenomena in materials under ultrashort pulsed laser irradiation of metals.the word ''abstract,'' but do replace the rest of this text.

  19. Effect of Electron Beam Irradiation on the Tensile Properties of Carbon Nanotubes Sheets and Yarns

    NASA Technical Reports Server (NTRS)

    Williams, Tiffany S.; Miller, Sandi G.; Baker, James S.; McCorkle, Linda S.; Meador, Michael A.

    2013-01-01

    Carbon nanotube sheets and yarns were irradiated using electron beam (e-beam) energy to determine the effect of irradiation dose on the tensile properties. Results showed that a slight change in tensile strength occurred after irradiating as-received CNT sheets for 20 minutes, and a slight decrease in tensile strength as the irradiation time approached 90 minutes. On the other hand, the addition of small molecules to the CNT sheet surface had a greater effect on the tensile properties of e-beam irradiated CNT sheets. Some functionalized CNT sheets displayed up to a 57% increase in tensile strength following 90 minutes of e-beam exposure. In addition, as-received CNT yarns showed a significant increase in tensile strength as the irradiation time increased.

  20. Characterization of blend hydrogels based on plasticized starch/cellulose acetate/carboxymethyl cellulose synthesized by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Senna, Magdy M.; Mostafa, Abo El-Khair B.; Mahdy, Sanna R.; El-Naggar, Abdel Wahab M.

    2016-11-01

    Blend hydrogels based on aqueous solutions of plasticized starch and different ratios of cellulose acetate (CA) and carboxymethyl cellulose (CMC) were prepared by electron beam irradiation (EB). The blends before and after EB irradiation were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The physico-chemical properties of blend hydrogels prepared by electron beam irradiation were improved compared to unirradiated blends.

  1. Contribution of electronic excitation to the structural evolution of ultrafast laser-irradiated tungsten nanofilms

    NASA Astrophysics Data System (ADS)

    Murphy, Samuel T.; Giret, Yvelin; Daraszewicz, Szymon L.; Lim, Anthony C.; Shluger, Alexander L.; Tanimura, Katsumi; Duffy, Dorothy M.

    2016-03-01

    The redistribution of the electron density in a material during laser irradiation can have a significant impact on its structural dynamics. This electronic excitation can be incorporated into two temperature molecular dynamics (2T-MD) simulations through the use of electronic temperature dependent potentials. Here, we study the structural dynamics of laser irradiated tungsten nanofilms using 2T-MD simulations with an electronic temperature dependent potential and compare the results to equivalent simulations that employ a ground-state interatomic potential. Electronic excitation leads to an expansion of the crystal and a decrease in the melting point of tungsten. During laser irradiation these factors ensure that the threshold fluences to the different melting regimes are reduced. Furthermore, both heterogenous and homogeneous melting are predicted to occur more rapidly due to excitation and oscillations in the film thickness will be accentuated.

  2. Electron beam irradiation crosslinked hydrogels based on tyramine conjugated gum tragacanth.

    PubMed

    Tavakol, Moslem; Dehshiri, Saeedeh; Vasheghani-Farahani, Ebrahim

    2016-11-01

    In the present study, electron beam irradiation was applied to prepare a chemically crosslinked hydrogel based on tyramine conjugated gum tragacanth. Then, the gel content, swelling behavior and cytotoxicity of the hydrogels were evaluated. The gel content of the hydrogels was in the range of 75-85%. Equilibrium swelling degree of the hydrogels decreased from 51 to 14 with increasing polymer concentration and irradiation dose. Moisture retention capability of the hydrogels after 5h incubation at 37°C was in the range of 45-52 that is comparable with of commercial hydrogels. The cytotoxicity analysis showed the good biocompatibility of hydrogels. These results indicated that electron beam irradiation is a promising method to prepare chemically crosslinked tyramine conjugated gum tragacanth hydrogels for biomedical applications. Also, the versatility of electron beam irradiation for crosslinking of a variety of polymers possessing tyramine groups was demonstrated.

  3. An experience of electron beam (EB) irradiated gemstones in Malaysian nuclear agency

    NASA Astrophysics Data System (ADS)

    Idris, Sarada; Hairaldin, Siti Zulaiha; Tajau, Rida; Karim, Jamilah; Jusoh, Suhaimi; Ghazali, Zulkafli; Ahmad, Shamshad

    2014-02-01

    In Nuclear Malaysia, a study on gemstone irradiation using beta particle is conducted. The purpose of the study is to evaluate the gemstone colour enhancement by using different kind of precious and non-precious gemstones. By using irradiation technique, selected gemstones are exposed to highly ionizing radiation electron beam to knock off electrons to generate colour centres culminating in the introduction of deeper colours. The colour centres may be stable or unstable depending on the nature of colour centre produced. The colour change of irradiated stones were measured by HunterLab colour measurement. At 50 kGy, Topaz shows changes colour from colourless to golden. Meanwhile pearl shows changes from pale colour to grey. Kunzite and amethyst shows colour changes from colorless to green and pale colour to purple. Gamma survey meter measurement confirmed that irradiation treatment with 3 MeV electron beam machine does not render any activation that activate the gems to become radioactive.

  4. An experience of electron beam (EB) irradiated gemstones in Malaysian nuclear agency

    SciTech Connect

    Idris, Sarada Hairaldin, Siti Zulaiha Tajau, Rida Karim, Jamilah Jusoh, Suhaimi Ghazali, Zulkafli; Ahmad, Shamshad

    2014-02-12

    In Nuclear Malaysia, a study on gemstone irradiation using beta particle is conducted. The purpose of the study is to evaluate the gemstone colour enhancement by using different kind of precious and non-precious gemstones. By using irradiation technique, selected gemstones are exposed to highly ionizing radiation electron beam to knock off electrons to generate colour centres culminating in the introduction of deeper colours. The colour centres may be stable or unstable depending on the nature of colour centre produced. The colour change of irradiated stones were measured by HunterLab colour measurement. At 50 kGy, Topaz shows changes colour from colourless to golden. Meanwhile pearl shows changes from pale colour to grey. Kunzite and amethyst shows colour changes from colorless to green and pale colour to purple. Gamma survey meter measurement confirmed that irradiation treatment with 3 MeV electron beam machine does not render any activation that activate the gems to become radioactive.

  5. Electron beam irradiation crosslinked hydrogels based on tyramine conjugated gum tragacanth.

    PubMed

    Tavakol, Moslem; Dehshiri, Saeedeh; Vasheghani-Farahani, Ebrahim

    2016-11-01

    In the present study, electron beam irradiation was applied to prepare a chemically crosslinked hydrogel based on tyramine conjugated gum tragacanth. Then, the gel content, swelling behavior and cytotoxicity of the hydrogels were evaluated. The gel content of the hydrogels was in the range of 75-85%. Equilibrium swelling degree of the hydrogels decreased from 51 to 14 with increasing polymer concentration and irradiation dose. Moisture retention capability of the hydrogels after 5h incubation at 37°C was in the range of 45-52 that is comparable with of commercial hydrogels. The cytotoxicity analysis showed the good biocompatibility of hydrogels. These results indicated that electron beam irradiation is a promising method to prepare chemically crosslinked tyramine conjugated gum tragacanth hydrogels for biomedical applications. Also, the versatility of electron beam irradiation for crosslinking of a variety of polymers possessing tyramine groups was demonstrated. PMID:27516298

  6. Effect of electron beam irradiation on the viscosity of carboxymethylcellulose solution

    NASA Astrophysics Data System (ADS)

    Choi, Jong-il; Lee, Hee-Sub; Kim, Jae-Hun; Lee, Kwang-Won; Chung, Young-Jin; Byun, Myung-Woo; Lee, Ju-Woon

    2008-12-01

    In this study, the effects of an electron beam irradiation on the viscosity of a carboxymethylcellulose (CMC) solution were investigated. The viscosity of the CMC solution was decreased with an increase in the irradiation dose. Interestingly, the extent of the degradation of the CMC was found to decrease with an increase of the CMC concentration in the solution. The change of the average molar mass confirmed the decrease in the viscosity due to the degradation of the polymer. The energy of the electron beam also affected the degradation of the CMC. Lower degradation of the CMC was obtained with a decreasing electron beam energy due to its lower penetration. Addition of vitamin C as a radical scavenger to the solution and an irradiation at -70 °C were shown to be moderately effective in preventing a decrease in the viscosity of the solution by irradiation.

  7. Economics of food irradiation: Comparison between electron accelerators and cobalt-60

    NASA Astrophysics Data System (ADS)

    Morrison, R. M.

    The Codex Alimentarius Commission's proposed international standard permits three types of ionizing radiation to be used on foods: gamma rays from radioactive cobalt-60 or cesium-137, high energy electrons, and x-rays. The latter two types of radiation are produced by electron accelerators powered by electricity. Unlike gamma rays and x-rays which can penetrate pallet loads of foods, electrons of the allowed energy levels only penetrate 1 to 3 inches when irradiated from one side. Thus, electrons are limited to treating the surface of foods or foods in thin packages or a shallow stream of grains, powders, or liquids. Average costs per kilogram (kg) of irradiating selected foods are similar for the electron accelerator and cobalt-60 irradiators analyzed in this study, but initial investment costs generally vary by U.S. $1 million. Irradiation treatment costs range from 1 to 15 U.S. cents per kg for the foods and annual volumes examined with larger volumes having lower treatment costs. Cobalt-60 is less expensive than electrons when annual volumes are below 23 million kgs. For radiation source requirements above the equivalent of about 1 million curies of cobalt-60, electrons become more economical. The largest differences in costs occur with the papaya irradiators where using x-rays to penetrate the fruit is more expensive than using cobalt-60.

  8. Modification of Defect Structures in Graphene by Electron Irradiation: Ab Initio Molecular Dynamics Simulations

    SciTech Connect

    Wang, Zhiguo; Zhou, Yungang; Bang, Junhyeok; Prange, Micah P.; Zhang, Shengbai; Gao, Fei

    2012-08-02

    Defects play an important role on the unique properties of the sp2-bonded materials, such as graphene. The creation and evolution of mono-vacancy, di-vacancy, Stone-Wales (SW) and grain boundaries (GBs) under irradiation in graphene are investigated using density functional theory and time-dependent density functional theory molecular dynamics simulations. It is of great interest to note that the patterns of these defects can be controlled through electron irradiation. The SW defects can be created by electron irradiation with energy of above the displacement threshold energy (Td, {approx}19 eV) and can be healed with an energy (14-18 eV) lower than Td. The transformation between four types of divacancies, V2(5-8-5), V2(555-777), V2(5555-6-7777), and V2(55-77) can be realized through bond rotation induced by electron irradiation. The migrations of divancancies, SW defects, and GBs can also be controlled by electron irradiation. Thus, electron irradiation can serve as an important tool to modify morphology in a controllable manner, and to tailor the physical properties of graphene.

  9. Enhancement of biodegradability of real textile and dyeing wastewater by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    He, Shijun; Sun, Weihua; Wang, Jianlong; Chen, Lvjun; Zhang, Youxue; Yu, Jiang

    2016-07-01

    A textile and dyeing wastewater treatment plant is going to be upgraded due to the stringent discharge standards in Jiangsu province, China, and electron beam irradiation is considering to be used. In order to determine the suitable location of the electron accelerator in the process of wastewater treatment plant, the effects of electron beam (EB) irradiation on the biodegradability of various real wastewater samples collecting from the different stages of the wastewater treatment plant, the values of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and the ratio of BOD5 and COD (BOD5/COD), were compared before and after EB irradiation. During EB irradiation process, color indices and absorbance at 254 nm wavelength (UV254) of wastewater were also determined. The results showed that EB irradiation pre-treatment cannot improve the biodegradability of raw textile and dyeing wastewater, which contains a large amount of biodegradable organic matters. In contrast, as to the final effluent of biological treatment process, EB irradiation can enhance the biodegradability to 224%. Therefore, the promising way is to apply EB irradiation as a post-treatment of the conventional biological process.

  10. Paramagnetic defects induced by electron irradiation in barium hollandite ceramics for caesium storage.

    PubMed

    Aubin-Chevaldonnet, V; Gourier, D; Caurant, D; Esnouf, S; Charpentier, T; Costantini, J M

    2006-04-26

    We have studied by electron paramagnetic resonance the mechanism of defect production by electron irradiation in barium hollandite, a material used for immobilization of radioactive caesium. The irradiation conditions were the closest possible to those occurring in Cs storage waste forms. Three paramagnetic defects were observed, independently of the irradiation conditions. A hole centre (H centre) is attributed to a superoxide ion O(2)(-) originating from hole trapping by interstitial oxygen produced by electron irradiation. An electron centre (E(1) centre) is attributed to a Ti(3+) ion adjacent to the resulting oxygen vacancy. Another electron centre (E(2) centre) is attributed to a Ti(3+) ion in a cation site adjacent to an extra Ba(2+) ion in a neighbouring tunnel, originating from barium displacement by elastic collisions. Comparison of the effects of external irradiations by electrons with the β-decay of Cs in storage waste forms is discussed. It is concluded that the latter would be dominated by E(1) and H centres rather than E(2) centres. PMID:21690754

  11. Nitrogen-doped carbon nanotubes under electron irradiation simulated with a tight-binding model

    SciTech Connect

    Loponen, T.; Nieminen, R. M.; Krasheninnikov, A. V.; Kaukonen, M.

    2006-08-15

    Experiments show that nitrogen-doped carbon nanotubes subjected to the electron beam in a transmission electron microscope can easily lose dopant atoms and that overall they are less stable under electron irradiation than the pristine tubes. To understand the lower stability of nitrogen-doped nanotubes we use a density-functional-theory-based tight-binding model and simulate impacts of energetic electrons onto the nanotubes. We show that the dopant atom displacement energy and thus the electron threshold energy is lower for nanotubes with smaller diameter and that, independent of the nanotube diameter, the dopant nitrogen atoms can be displaced more easily than the host carbon atoms. Our results set a limit on the threshold electron energy for damage production in N-doped tubes and indicate that spatially localized electron irradiation of doped nanotubes can be used for local atomic and band structure engineering.

  12. Measurements of the UV and VUV transmission of optical materials during high energy electron irradiation

    NASA Technical Reports Server (NTRS)

    Palma, G. E.

    1972-01-01

    An experimental program was conducted in which the optical transmission of several transparent materials was measured during high energy electron irradiation. These experiments were conducted using the Dynamitron electron accelerator as a continuous source of 1.5 MeV electrons and the LINAC electron accelerator as a pulsed source of 5-7 MeV electrons. The experimental program consisted of three major portions. The first portion, the optical transmission of fused silica, BeO, MgF2, and LiF was measured at vacuum ultraviolet wavelengths in the range 1550-2000 A during ambient temperature, 1.5 MeV electron irradiation at ionizing dose rates to 0.5 Mrad/sec. In the second portion of the program, the optical transmission of fused silica and BeO was measured in the range 2000-3000 A during high dose rate, elevated temperature 1.5 MeV electron irradiation. In particular, accurate measurements of the optical transmission were made at ionizing dose rates as high as 10 Mrad/sec. In the final portion of the program, the optical transmission of fused silica and BeO was measured in the wavelength range 2000-3000 A during pulsed 5 and 7 MeV electron irradiation from the LINAC accelerator. The maximum time averaged ionizing dose rate was limited to 0.75 Mrad/sec due to accelerator limitations.

  13. Photocatalytic activity of 6.5 MeV electron-irradiated ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Sapnar, K. B.; Ghule, L. A.; Bhoraskar, S. V.; Garadkar, K. M.; Dhole, S. D.; Bhoraskar, V. N.

    2012-04-01

    The microwave-synthesized zinc-oxide (ZnO) nanonorods of average length of ∼ 1500 nm and diameter ∼ 100 nm were irradiated with 6.5 meV electrons. From sample to sample, the electron fluence was varied over the range 5×1014 to 2.5×1015 e-cm-2. The pre- and post-electron-irradiated ZnO nanorods were characterized by X-ray diffraction, UV-VIS, EDAX, scanning electron microscopy, transmission electron microscopy, and BET methods. The results show that after electron irradiation, the ZnO nanorods could retain the hexagonal phase with the wurtzite structure; however, the average length of the ZnO nanorods reduced to ∼ 800 nm. Moreover, the oxygen atoms from a fraction of ZnO molecules were dislodged, and the process contributed to the formation of Zn-ZnO mixed phase, with increased zinc to oxygen ratio. In the photo-degradation of Rhodamine-B, a significant enhancement in the photocatalytic activity of the electron-irradiated ZnO nanorods was observed. This could be attributed to the induced defects, reduced dimensions, and increased surface area of the ZnO nanorods, in addition to the formation of the Zn-ZnO phase. All these could collectively contribute to the effective separation of the photogenerated electrons from the holes on the ZnO nanorods, and therefore enhance the photocatalytic activity under UV exposure.

  14. Chemical patterning of Ag(111): Spatially confined oxide formation induced by electron beam irradiation

    SciTech Connect

    Guenther, S.; Reichelt, R.; Wintterlin, J.; Barinov, A.; Mentes, T. O.; Nino, M. A.; Locatelli, A.

    2008-12-08

    Low energy electron irradiation of a Ag(111) surface during NO{sub 2} adsorption at 300 K induces formation of Ag oxide. Using a spatially confined electron beam, small Ag{sub 2}O spots could be grown with a sharp, {approx}100 nm wide, boundary to the nonirradiated metallic surface. Since the structure size will mainly depend on the sharpness of the irradiating electron beam, this process has the potential of a single step nanostructuring process. Temperature treatment offers an easy way to manipulate the boundary between oxide and metallic silver by steering a chemical front.

  15. Radiation-Induced Centers in Lead Silicate Glasses Irradiated by Stationary and Pulsed Electron Beams

    NASA Astrophysics Data System (ADS)

    Zhidkov, I. S.; Zatsepin, A. F.; Konev, S. F.; Cholakh, S. O.

    2015-08-01

    Radiation-induced centers formed in heavy flint glasses irradiated by electron beams are investigated by the methods of optical and EPR spectroscopy. It is revealed that stable and short-living optical absorption centers of close natures are formed under irradiation by fast electrons. A correlation is established between the stable optical absorption bands and the EPR signals interpreted as signals of the (Pb2+)/h+ hole centers. The shortliving color centers are formed due to short-term distortion of the O-Pb bonds, and the stable centers are formed due to the spatial separation, thermalization, and subsequent stabilization of excited electrons and holes in tails of the localized states. Irradiation by electron beams leads to a change in the spectral characteristics of the fundamental absorption edge and, in particular, of the Urbach energy that determines the degree of structural disorder.

  16. Remotion of organic compounds of actual industrial effluents by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Sampa, M. H. O.; Duarte, C. L.; Rela, P. R.; Somessari, E. S. R.; Silveira, C. G.; Azevedo, A. L.

    1998-06-01

    Organic compounds has been a great problem of environmental pollution, the traditional methods are not effecient on removing these compounds and most of them are deposited to ambient and stay there for long time causing problems to the environment. Ionizing radiation has been used with success to destroy organic molecules. Actual industrial effluents were irradiated using IPEN's electron beam wastewater pilot plant to study organic compounds degradation. The samples were irradiated with and without air mixture by different doses. Irradiation treatment efficiency was evaluated by the Cromatography Gas Analyses of the samples before and after irradiation. The studied organic compounds were: phenol, chloroform, tetrachloroethylene (PCE), carbon tetrachloride, trichloroethylene (TCE), 1,1-dichloroethane, dichloromethane, benzene, toluene and xilene. A degradation superior to 80% was achieved for the majority of the compounds with air addition and 2kGy delivered dose condition. For the samples that were irradiated without air addition the degradation was higher.

  17. Effect of electron irradiation and heat on the structure of hairtail surimi

    NASA Astrophysics Data System (ADS)

    Lin, Xianping; Yang, Wenge; Xu, Dalun; Wang, Lili

    2015-09-01

    Hairtail surimi was treated with electron radiation and heat, the chemical interactions, thermal properties and the structural changes were determined. The chemical interaction data indicate that the contribution of disulfide bonds to heat-induced gel formation was decisive. Irradiation promoted the formation of disulfide bonds during the cooking. Differential scanning calorimetry showed that the myosin and actin thermal transitions of irradiated surimi shifted to lower temperatures. And the myosin thermal stability of irradiated surimi was lower than unirradiated surimi. The Fourier transform infrared and Raman results showed the irradiation and heat treatments decreased the α-helix structure content and increased β-sheet structure content. This study may provide useful information for the effect of irradiation on the surimi gel properties.

  18. Advanced protocol for the detection of irradiated food by electron spin resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Shimoyama, Yuhei; Ukai, Mitsuko; Nakamura, Hideo

    2007-11-01

    Using ESR (electron spin resonance) spectroscopy, we found various free radicals in a pepper before and after irradiation. The representative ESR spectrum of the pepper composed of a sextet centered at g=2.0, a singlet at the same g-value and a singlet at g=4.0. This reflects the evidence of three independent radicals in the pepper before irradiation. Upon gamma ray irradiation, a new pair of signals appeared. The progressive saturation behavior (PSB) at various microwave power levels indicates quite different relaxation behaviors of those signals. For the evaluation of radiation-induced radicals and irradiation effects we propose a new protocol using the PSB method. This would call for an advanced protocol for the detection of irradiated foods.

  19. Preparation of polymer-coated separators using an electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Sohn, Joon-Yong; Gwon, Sung-Jin; Choi, Jae-Hak; Shin, Junhwa; Nho, Young-Chang

    2008-12-01

    A polymer-coated polyethylene (PE) separator was prepared by a dip-coating of PVDF-HFP/PEGDMA on both sides of a PE separator followed by an electron beam irradiation. The thermal and electrochemical properties of the polymer-coated PE separator were investigated by using FT-IR, SEM, DSC and an impedance analyzer. The results showed that the coated PVDF-HFP/PEGDMA layer was covalently bound to the PE separator and also crosslinked by an electron beam irradiation. Thermal shrinkage dramatically decreased with an increase in the absorption dose and the PEGDMA content due to the crosslinking of the coated PVDF-HFP/PEGDMA by an irradiation. The PE separator coated with the composition of PVDF-HFP/PEGDMA (9.5/0.5) and irradiated to 150 kGy showed the highest electrolyte uptake of 125% and ionic conductivity of 3.82 × 10 -4 S/cm at room temperature.

  20. Microplastic deformation of polycrystalline iron and molybdenum subjected to high-current electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Dudarev, E. F.; Pochivalova, G. P.; Proskurovskii, D. I.; Rotshtein, V. P.; Markov, A. B.

    1996-03-01

    A technique for determination of residual stresses at various distances from the irradiated surface is proposed. It is established for iron and molybdenum that compressive stresses are set up under irradiation by low-energy high-current electron beams and that their values decrease sharply with increasing distance from the surface. The residual stresses are much smaller in absolute magnitude than those operating during irradiation. It is shown that the change in resistance to microplastic deformation on irradiation with low-energy high-current electron beams is governed not only by formation of a gradient dislocation substructure in the surface layer, but also by the residual stresses and the appearance of the Bauschinger effect.

  1. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters.

    PubMed

    Kim, Jae Joon; Ha, Jun Mok; Lee, Hyeok Moo; Raza, Hamid Saeed; Park, Ji Won; Cho, Sung Oh

    2016-08-01

    The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor.

  2. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters.

    PubMed

    Kim, Jae Joon; Ha, Jun Mok; Lee, Hyeok Moo; Raza, Hamid Saeed; Park, Ji Won; Cho, Sung Oh

    2016-08-01

    The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor. PMID:27399874

  3. Comprehensive stabilization mechanism of electron-beam irradiated polyacrylonitrile fibers to shorten the conventional thermal treatment

    NASA Astrophysics Data System (ADS)

    Park, Sejoon; Yoo, Seung Hwa; Kang, Ha Ri; Jo, Seong Mu; Joh, Han-Ik; Lee, Sungho

    2016-06-01

    An electron beam was irradiated on polyacrylonitrile (PAN) fibers prior to thermal stabilization. The electron-beam irradiation effectively shortened the thermal stabilization process by one fourth compared with the conventional thermal stabilization process. A comprehensive mechanistic study was conducted regarding this shortening of the thermal stabilization by electron-beam irradiation. Various species of chain radicals were produced in PAN fibers by electron-beam irradiation and existed for a relatively long duration, as observed by electron spin resonance spectroscopy. Subsequently, these radicals were gradually oxidized to peroxy radicals in the presence of oxygen under storage or heating. We found that these peroxy radicals (CO) enabled such an effective shortcut of thermal stabilization by acting as intermolecular cross-linking and partial aromatization points in the low temperature range (100–130 °C) and as earlier initiation seeds of successive cyclization reactions in the next temperature range (>130–140 °C) of thermal stabilization. Finally, even at a low irradiation dose (200 kGy), followed by a short heat treatment (230 °C for 30 min), the PAN fibers were sufficiently stabilized to produce carbon fibers with tensile strength and modulus of 2.3 and 216 GPa, respectively, after carbonization.

  4. Comprehensive stabilization mechanism of electron-beam irradiated polyacrylonitrile fibers to shorten the conventional thermal treatment

    NASA Astrophysics Data System (ADS)

    Park, Sejoon; Yoo, Seung Hwa; Kang, Ha Ri; Jo, Seong Mu; Joh, Han-Ik; Lee, Sungho

    2016-06-01

    An electron beam was irradiated on polyacrylonitrile (PAN) fibers prior to thermal stabilization. The electron-beam irradiation effectively shortened the thermal stabilization process by one fourth compared with the conventional thermal stabilization process. A comprehensive mechanistic study was conducted regarding this shortening of the thermal stabilization by electron-beam irradiation. Various species of chain radicals were produced in PAN fibers by electron-beam irradiation and existed for a relatively long duration, as observed by electron spin resonance spectroscopy. Subsequently, these radicals were gradually oxidized to peroxy radicals in the presence of oxygen under storage or heating. We found that these peroxy radicals (CO) enabled such an effective shortcut of thermal stabilization by acting as intermolecular cross-linking and partial aromatization points in the low temperature range (100-130 °C) and as earlier initiation seeds of successive cyclization reactions in the next temperature range (>130-140 °C) of thermal stabilization. Finally, even at a low irradiation dose (200 kGy), followed by a short heat treatment (230 °C for 30 min), the PAN fibers were sufficiently stabilized to produce carbon fibers with tensile strength and modulus of 2.3 and 216 GPa, respectively, after carbonization.

  5. Comprehensive stabilization mechanism of electron-beam irradiated polyacrylonitrile fibers to shorten the conventional thermal treatment

    PubMed Central

    Park, Sejoon; Yoo, Seung Hwa; Kang, Ha Ri; Jo, Seong Mu; Joh, Han-Ik; Lee, Sungho

    2016-01-01

    An electron beam was irradiated on polyacrylonitrile (PAN) fibers prior to thermal stabilization. The electron-beam irradiation effectively shortened the thermal stabilization process by one fourth compared with the conventional thermal stabilization process. A comprehensive mechanistic study was conducted regarding this shortening of the thermal stabilization by electron-beam irradiation. Various species of chain radicals were produced in PAN fibers by electron-beam irradiation and existed for a relatively long duration, as observed by electron spin resonance spectroscopy. Subsequently, these radicals were gradually oxidized to peroxy radicals in the presence of oxygen under storage or heating. We found that these peroxy radicals (CO) enabled such an effective shortcut of thermal stabilization by acting as intermolecular cross-linking and partial aromatization points in the low temperature range (100–130 °C) and as earlier initiation seeds of successive cyclization reactions in the next temperature range (>130–140 °C) of thermal stabilization. Finally, even at a low irradiation dose (200 kGy), followed by a short heat treatment (230 °C for 30 min), the PAN fibers were sufficiently stabilized to produce carbon fibers with tensile strength and modulus of 2.3 and 216 GPa, respectively, after carbonization. PMID:27349719

  6. Comprehensive stabilization mechanism of electron-beam irradiated polyacrylonitrile fibers to shorten the conventional thermal treatment.

    PubMed

    Park, Sejoon; Yoo, Seung Hwa; Kang, Ha Ri; Jo, Seong Mu; Joh, Han-Ik; Lee, Sungho

    2016-01-01

    An electron beam was irradiated on polyacrylonitrile (PAN) fibers prior to thermal stabilization. The electron-beam irradiation effectively shortened the thermal stabilization process by one fourth compared with the conventional thermal stabilization process. A comprehensive mechanistic study was conducted regarding this shortening of the thermal stabilization by electron-beam irradiation. Various species of chain radicals were produced in PAN fibers by electron-beam irradiation and existed for a relatively long duration, as observed by electron spin resonance spectroscopy. Subsequently, these radicals were gradually oxidized to peroxy radicals in the presence of oxygen under storage or heating. We found that these peroxy radicals (CO) enabled such an effective shortcut of thermal stabilization by acting as intermolecular cross-linking and partial aromatization points in the low temperature range (100-130 °C) and as earlier initiation seeds of successive cyclization reactions in the next temperature range (>130-140 °C) of thermal stabilization. Finally, even at a low irradiation dose (200 kGy), followed by a short heat treatment (230 °C for 30 min), the PAN fibers were sufficiently stabilized to produce carbon fibers with tensile strength and modulus of 2.3 and 216 GPa, respectively, after carbonization. PMID:27349719

  7. Nanopore integrated with Au clusters formed under electron beam irradiation for single molecule analysis

    NASA Astrophysics Data System (ADS)

    Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Kim, Sung In; Yoo, Jung Ho; Park, Kyung Jin; Park, Nam Kyou; Kim, Yong-Sang

    2016-02-01

    Recently the single molecules such as protein and deoxyribonucleic acid (DNA) have been successfully characterized using a solidstate nanopore with an electrical detection technique. However, the optical plasmonic nanopore has yet to be fabricated. The optical detection technique can be better utilized as next generation ultrafast geneome sequencing devices due to the possible utilization of the current optical technique for genome sequencing. In this report, we have investigated the Au nanopore formation under the electron beam irradiation on an Au aperture. The circular-type nanoopening with ~ 5 nm diameter on the diffused membrane is fabricated by using 2 keV electron beam irradiation by using field emission scanning electron microscopy (FESEM). We found the Au cluster on the periphery of the drilled aperture under a 2 keV electron beam irradiation. Immediately right after electron beam irradiation, no Au cluster and no Au crystal lattice structure on the diffused plane are observed. However, after the sample was kept for ~ 6 months under a room environment, the Au clusters are found on the diffused membrane and the Au crystal lattice structures on the diffused membrane are also found using high resolution transmission electron microscopy. These phenomena can be attributed to Ostwald ripening. In addition, the Au nano-hole on the 40 nm thick Au membrane was also drilled by using 200 keV scanning transmission electron microscopy.

  8. Formation of hydroxylamine (NH2OH) in electron-irradiated ammonia-water ices.

    PubMed

    Zheng, Weijun; Kaiser, Ralf I

    2010-04-29

    We investigated chemical and physical processes in electron-irradiated ammonia-water ices at temperatures of 10 and 50 K. Chemically speaking, the formation of hydroxylamine (NH(2)OH) was observed in electron-irradiated ammonia-water ices. The synthesis of molecular hydrogen (H(2)), molecular nitrogen (N(2)), molecular oxygen (O(2)), hydrazine (N(2)H(4)), and hydrogen peroxide (H(2)O(2)), which was also monitored in previous irradiation of pure ammonia and water ices, was also evident. These newly formed species were trapped inside of the ices and were released into the gas phase during the warm-up phase of the sample after the irradiation. A quantitative analysis of the data showed that the production rates of the newly formed species at 10 K are higher compared to those at 50 K. Our studies also suggest that hydroxylamine is likely formed by the recombination of amino (NH(2)) with hydroxyl (OH) radicals inside of the ices. Considering the physical effects on the ice sampled during the irradiation, the experiments provided compelling evidence that the crystalline ammonia-water ice samples can be partially converted to amorphous ices during the electron irradiation; similar to the chemical processes, the irradiation-induced amorphization of the ices is faster at 10 K than that at 50 K--a finding which is similar to electron-irradiated crystalline water ices under identical conditions. However, the amorphization of water in water-ammonia ices was found to be faster than that in pure water ices at identical temperatures.

  9. Structure and properties of binary polystyrene-epoxy acrylate oligomer mixtures irradiated by electron beams

    SciTech Connect

    Lomonosova, N.V.

    1995-03-01

    The change in the structure of oriented polymer-oligomer systems based on polystyrene (PS) with M > 10{sup 6} and epoxy acrylate oligomers (aliphatic and aromatic) under irradiation by accelerated electrons was studied using birefringence, isometric heating, IR dichroism, and thermooptical analysis. Mechanical properties of these systems were investigated. It was found that, by adding aliphatic epoxy acrylate to PS and further irradiating this mixture, one can obtain both isotropic and oriented composites with higher strengths, elasticity moduli, and glass transition temperatures.

  10. Shelf life and sensory characteristics of baby spinach subjected to electron beam irradiation.

    PubMed

    Neal, Jack A; Booren, Betsy; Cisneros-Zevallos, Luis; Miller, Rhonda K; Lucia, Lisa M; Maxim, Joseph E; Castillo, Alejandro

    2010-08-01

    The use of ionizing radiation for the control of foodborne pathogens and extending the shelf life of fresh iceberg lettuce and fresh spinach has recently been approved by the U.S. Food and Drug Administration. The efficacy of electron beam irradiation for controlling foodborne pathogens has been reported. For this experiment, the effectiveness of electron beam irradiation on the microbiological and sensory characteristics of fresh spinach was studied. Total aerobic plate counts were reduced by 2.6 and 3.2 log CFU/g at 0.7 and 1.4 kGy, respectively. Lactic acid bacteria were reduced at both doses of e-beam but grew slowly over the 35 d of the experiment. Yeasts and molds were not reduced in samples exposed to 0.7 kGy whereas 1.4 kGy significantly reduced microbial counts. Gas compositions (O(2) and CO(2)) were significantly different than controls. Oxygen levels inside the spinach sample bags decreased over time; however, O(2) levels did not drop below 1% that can induce anaerobic fermentation. CO(2) levels for all treatments increased through day 4; yet 7 d after irradiation, CO(2) level differences were not significant in both control and irradiated samples. Irradiation dose did not affect the basic tastes, aromatics, or mouth feels of fresh spinach, however; hardness attributes decreased as irradiated dose increased and slimy attributes of fresh spinach were higher in control samples compared to irradiated samples.

  11. Size-dependent crystalline fluctuation and growth mechanism of bismuth nanoparticles under electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Wu, Sujuan; Jiang, Yi; Hu, Lijun; Sun, Jianguo; Wan, Piaopiao; Sun, Lidong

    2016-06-01

    Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non-crystalline one. This is promising for applications in nanofabrication where high quality interfaces are desired between two joining parts.Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non

  12. Effects of electron-phonon coupling and electron diffusion on ripples growth on ultrafast-laser-irradiated metals

    SciTech Connect

    Colombier, J. P.; Garrelie, F.; Faure, N.; Reynaud, S.; Bounhalli, M.; Audouard, E.; Stoian, R.; Pigeon, F.

    2012-01-15

    Metals exposed to ultrafast laser irradiation close to ablative regimes show often a submicron-scale (near 0.5 {mu}m) periodic organization of the surface as ripples. Using two classes of metallic materials (transition and noble), we have determined that the ripples amplitude is strongly correlated to the material transport properties, namely electron-phonon relaxation strength, electronic diffusion, and to the energy band characteristics of the electronic laser excitation. This particularly depends on the topology of the electronic structure, including d-band effects on electronic excitation. Comparing the effects of electron-phonon nonequilibrium lifetimes for the different metals under similar irradiation conditions, we indicate how the electron-phonon coupling strength affects the electronic thermal diffusion, the speed of phase transformation and impacts on the ripples contrast. The highest contrast is observed for ruthenium, where the electron-phonon coupling is the strongest, followed by tungsten, nickel, and copper, the latter with the least visible contrast. The dependence of surface patterns contrast with fluence is linked to the dependence of the relaxation characteristics with the electronic temperature.

  13. Preliminary low temperature electron irradiation of triple junction solar cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2005-01-01

    JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature.

  14. Effects of gamma and electron beam irradiation on the microbial quality of steamed tofu rolls

    NASA Astrophysics Data System (ADS)

    Jia, Qian; Gao, Meixu; Li, Shurong; Wang, Zhidong

    2013-01-01

    The effectiveness of two kinds of radiation processing, gamma and electron beam (ebeam) irradiation, for the inactivation of Staphylococcus aureus, Salmonella enteritidis and Listeria innocua which were inoculated in pre-sterilised steamed tofu rolls was studied. The corresponding effects of both irradiation types on total bacterial counts (TBCs) in commercial steamed tofu rolls available in the market were also examined. The microbiological results demonstrated that gamma irradiation yielded D10 values of 0.20, 0.24 and 0.22 kGy for S. aureus, S. enteritidis and L. innocua, respectively. The respective D10 values for ebeam irradiation were 0.31, 0.35 and 0.27 kGy. Gamma and ebeam irradiation yielded D10 values of 0.48 and 0.43 kGy for total bacterial counts in commercial steamed tofu rolls, respectively. The results suggest that ebeam irradiation has similar effect on decreasing TBCs in steamed tofu rolls, and gamma irradiation is slightly more effective than ebeam irradiation in reducing the populations of pathogenic bacteria. The observed differences in D10-values between them might be due to the significant differences in dose rate applied, and radiation processing of soybean products to improve their microbial quality could be available for other sources of protein.

  15. Electron microscopic studies of damage evolution in fission neutron-irradiated metals

    NASA Astrophysics Data System (ADS)

    Shimomura, Y.; Yoshida, H.; Kiritani, M.; Kitagawa, K.; Yamakawa, K.

    1985-08-01

    The same kinds of specimens of both foil and bulk of metals, as those irradiated previously with D-T neutrons at RTNS-II, were irradiated with fission neutrons at KUR. The irradiations were performed at 20 and 350 K to fluences of 5 × 10 16 and 1 × 10 19 n/cm 2(E > 0.1 MeV), respectively. The results on pure gold are described to exemplify the typical value of cascade defects. A cascade in fission neutron irradiated gold consists of 2.2 small defects on average. This is compared with 6.7 small defects for the fusion neutron irradiation. The cross section for the formation of observed cascade defects is 0.15 barn, which is a twelveth of that in fusion neutron irradiation. The cryotransfer of the thin foil to the electron microscope was carried out to observe the cascade defects at low temperatures. The average size of cascade defects in fission neutron-irradiated gold was much smaller than that in fusion irradiation. The damage evolution in the bulk specimen was also examined.

  16. Evaluation of fatigue crack behavior in electron beam irradiated polyethylene pipes

    NASA Astrophysics Data System (ADS)

    Pokharel, Pashupati; Jian, Wei; Choi, Sunwoong

    2016-09-01

    A cracked round bar (CRB) fatigue test was employed to determine the slow crack growth (SCG) behavior of samples from high density polyethylene (HDPE) pipes using PE4710 resin. The structure property relationships of fatigue failure of polyethylene CRB specimens which have undergone various degree of electron beam (EB) irradiation were investigated by observing fatigue failure strength and the corresponding fracture surface morphology. Tensile test of these HDPE specimens showed improvements in modulus and yield strength while the failure strain decreased with increasing EB irradiation. The CRB fatigue test of HDPE pipe showed remarkable effect of EB irradiation on number of cycles to failure. The slopes of the stress-cycles to failure curve were similar for 0-100 kGy; however, significantly higher slope was observed for 500 kGy EB irradiated pipe. Also, the cycle to fatigue failure was seen to decrease as with EB irradiation in the high stress range, ∆σ=(16 MPa to 10.8 MPa); however, 500 kGy EB irradiated samples showed longer cycles to failure than the un-irradiated specimens at the stress range below 9.9 MPa and the corresponding initial stress intensity factor (∆KI,0)=0.712 MPa m1/2. The fracture surface morphology indicated that the cross-linked network in 500 kGy EB irradiated PE pipe can endure low dynamic load more effectively than the parent pipe.

  17. Electron spin resonance study of. gamma. -irradiated nylon 6

    SciTech Connect

    Takigami, S.; Matsumoto, I.; Nakamura, Y.

    1981-12-01

    The free radicals trapped in oriented nylon 6 filaments after ..gamma..-irradiation under vacuum at room temperature were studied by ESR spectroscopy. The ESR spectrum measured after irradiation gradually changed to a broad singlet spectrum with decrease in the intensity. The ESR spectrum consisted of radicals with different orientation effects with respect to the outer magnetic field, and saturation effects in reference to microwave power. The simulation of the ESR spectrum from a Gaussian function gave a better fit to the observed spectrum than the calculation from a Lorentzian function. From the resolution of the spectrum from a Gaussian function, the observed spectrum is generated from three kinds of radicals. The relative radical concentration for the first, second, and third radical is about 75%, 6%, and 19% of the total radical concentration, respectively. With regard to the stability of the radicals, the third radical shows a comparatively long lifetime. The first and second radicals show almost identical lifetime, and their concentrations reduce to about 40% of the initial value during the 2 days at room temperature.

  18. Size-dependent crystalline fluctuation and growth mechanism of bismuth nanoparticles under electron beam irradiation.

    PubMed

    Wu, Sujuan; Jiang, Yi; Hu, Lijun; Sun, Jianguo; Wan, Piaopiao; Sun, Lidong

    2016-06-16

    Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non-crystalline one. This is promising for applications in nanofabrication where high quality interfaces are desired between two joining parts.

  19. The effect of electron beam irradiation on silver-sodium ion exchange in silicate glasses

    NASA Astrophysics Data System (ADS)

    Sidorov, Alexander I.; Prosnikov, Mikhail A.

    2016-04-01

    It is shown experimentally that electron irradiation of sodium-silicate glasses makes possible the control of the subsequent ion exchange Ag+ ↔ Na+ process in a salt melt. The reason of this effect is the negatively charged regions formation in a glass volume during electron irradiation. The electric field, produced by these regions in glass volume, results in positive Na+ ions field migration into them. The spatial redistribution of Na+ ions results in the decrease of the ion exchange efficiency, or the ion exchange can be even blocked. This led to the decrease of the luminescence intensity of neutral silver molecular clusters in the irradiated zone, and effect on the silver nanoparticles formation during the subsequent thermal treatment. The observed effects can be used for the control of ion exchange processes during integrated optics devices fabrication, and for the electron-beam recording of optical information.

  20. Replica grating study. [response to aerospace environment, thermal vacuum, and electron irradiation

    NASA Technical Reports Server (NTRS)

    Gunter, R. C., Jr.

    1975-01-01

    Methods are outlined which were used to test the response of replica diffraction gratings to a space environment, specifically the response of the replica gratings to thermal-vacuum and electron irradiation stress. It is concluded that there probably is some degradation to thermal stress, but that there is probably no significant degradation due to a vacuum environment. It is further concluded that the degradation of performance of replica gratings because of electron irradiation is due to the interaction of the electrons and the replica grating substrate and not to the replication material itself. Replica and original gratings on the same substrate material should thus respond to particle irradiation in the same manner. A study is presented on the variation of refraction index of a space-related material, Nd:CaF2, with wavelength, percent neodymium doping, and temperature.

  1. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Technical Reports Server (NTRS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1996-01-01

    The measured degradation of epitaxial shallow homojunction n(+)/p InP solar cells under 1 MeV electron irradiation is correlated with that measured under 3 MeV proton irradiation based on 'displacement damage dose'. The measured data is analyzed as a function of displacement damage dose from which an electron to proton dose equivalency ratio is determined which enables the electron and proton degradation data to be described by a single degradation curve. It is discussed how this single curve can be used to predict the cell degradation under irradiation by any particle energy. The degradation curve is used to compare the radiation response of InP and GaAs/Ge cells on an absolute damage energy scale. The comparison shows InP to be inherently more resistant to displacement damage deposition than the GaAs/Ge.

  2. Surface modification study of low energy electron beam irradiated polycarbonate film

    NASA Astrophysics Data System (ADS)

    Nathawat, Rashi; Kumar, Anil; Kulshrestha, Vaibhav; Singh, M.; Ganesan, V.; Phase, D. M.; Vijay, Y. K.

    2007-05-01

    The effect of low energy electron beam irradiation on polycarbonate (PC) film has been studied here. The PC film of thickness 20 μm was exposed by 10 keV electron beam with 100 nA/cm 2 current density. The irradiated film was characterized by mean of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and residual gas analyzer (RGA). Formation of unsaturated bonds and partial graphitization of the surface layer are measured by XPS. Results of the AFM imaging shows electron implantation induce changes in surface morphology of the polymer film. The residual gas analyzer (RGA) spectrum of PC is recorded in situ during irradiation. The results show the change in cross-linking density of the polymer at the top surface.

  3. Hydroxyapatite-titanium interface reaction induced by keV electron irradiation

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Foti, G.

    1992-03-01

    Thin films of hydroxyapatite bioceramic, 5-50 Å in thickness, have been deposited on ion cleaned titanium surfaces to study the chemical-physical adhesion of metal-ceramic interfaces of biomedical devices (orthopaedic and dentistry prosthesis). Film deposition was performed in ultrahigh vacuum condition (10 -10 mbar) using 5 keV argon sputtering of hydroxyapatite matrix; the film thickness was measured in situ with Auger electron spectroscopy. The hydroxyapatite-titanium interface was irradiated with an electron beam of 0.5-5 keV energy and 0.2-2 A/cm 2 current density. During electron irradiation, Auger spectra show chemical shifts of phosphorus, titanium and oxygen peaks. The released electron energy induces modifications in the tetraedric phosphorus-oxygen groups with production of new chemical bonds between phosphorus, oxygen and titanium. Oxygen, for example, diffuses into the titanium interface forming titanium oxide. Chemical reactions induced by electron irradiation are driven by the metal-ceramic interface. Near the interface a strong and fast effect is observed while far from the interface a weak and slow effect occurs. Chemical reactions depend on the electron irradiation dose showing an inhibition threshold at about 10 19 e/cm 2 and, near the interface, a saturation condition at about 5 × 10 20 e/cm 2. Titanium-ceramic chemical reactions are inhibited if the substrate titanium surface is rich in oxide.

  4. Electrical and optoelectrical modification of cadmium sulfide nanobelts by low-energy electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Lijie; Liu, Manman; Zhao, Mei; Dong, Youqing; Zou, Chao; Yang, Keqin; Yang, Yun; Huang, Shaoming; Zhu, Da-Ming

    2016-09-01

    In this report, we describe a method for modifying electrical and optoelectrical properties of CdS nanobelts using low-energy (lower than 10 keV) e-beam irradiation in a scanning electron microscope. The electrical conductivity of the nanobelts was dramatically improved via the irradiation of e-beams. The modified conductivity of the nanobelts depends on the energy of the e-beam; it exhibits a larger photocurrent and higher external quantum efficiency but slower time-response than that before the modification. A possible mechanism about the modification is the increase of electron accumulation (injected electrons) in the nanobelts due to e-beam irradiation. In addition, the optoelectrical modification could be caused by the trapped electrons in the nanobelts and the decrease of contact resistance between the nanobelts and metal electrodes induced by e-beam irradiation. The results of this work are significant for the in situ study of semiconductor nanostructures in the electron microscope. Besides, the method of electrical and optoelectrical modification presented here has potential application in electronics and optoelectronics.

  5. Electrical and optoelectrical modification of cadmium sulfide nanobelts by low-energy electron beam irradiation.

    PubMed

    Zhang, Lijie; Liu, Manman; Zhao, Mei; Dong, Youqing; Zou, Chao; Yang, Keqin; Yang, Yun; Huang, Shaoming; Zhu, Da-Ming

    2016-09-30

    In this report, we describe a method for modifying electrical and optoelectrical properties of CdS nanobelts using low-energy (lower than 10 keV) e-beam irradiation in a scanning electron microscope. The electrical conductivity of the nanobelts was dramatically improved via the irradiation of e-beams. The modified conductivity of the nanobelts depends on the energy of the e-beam; it exhibits a larger photocurrent and higher external quantum efficiency but slower time-response than that before the modification. A possible mechanism about the modification is the increase of electron accumulation (injected electrons) in the nanobelts due to e-beam irradiation. In addition, the optoelectrical modification could be caused by the trapped electrons in the nanobelts and the decrease of contact resistance between the nanobelts and metal electrodes induced by e-beam irradiation. The results of this work are significant for the in situ study of semiconductor nanostructures in the electron microscope. Besides, the method of electrical and optoelectrical modification presented here has potential application in electronics and optoelectronics. PMID:27561004

  6. Monte Carlo Simulation of the Irradiation of Alanine Coated Film Dosimeters with Accelerated Electrons

    NASA Astrophysics Data System (ADS)

    Uribe, R. M.; Salvat, F.; Cleland, M. R.; Berejka, A.

    2009-03-01

    The Monte Carlo code PENELOPE was used to simulate the irradiation of alanine coated film dosimeters with electron beams of energies from 1 to 5 MeV being produced by a high-current industrial electron accelerator. This code includes a geometry package that defines complex quadratic geometries, such as those of the irradiation of products in an irradiation processing facility. In the present case the energy deposited on a water film at the surface of a wood parallelepiped was calculated using the program PENMAIN, which is a generic main program included in the PENELOPE distribution package. The results from the simulation were then compared with measurements performed by irradiating alanine film dosimeters with electrons using a 150 kW Dynamitron™ electron accelerator. The alanine films were placed on top of a set of wooden planks using the same geometrical arrangement as the one used for the simulation. The way the results from the simulation can be correlated with the actual measurements, taking into account the irradiation parameters, is described. An estimation of the percentage difference between measurements and calculations is also presented.

  7. Monte Carlo Simulation of the Irradiation of Alanine Coated Film Dosimeters with Accelerated Electrons

    SciTech Connect

    Uribe, R. M.; Salvat, F.; Cleland, M. R.; Berejka, A.

    2009-03-10

    The Monte Carlo code PENELOPE was used to simulate the irradiation of alanine coated film dosimeters with electron beams of energies from 1 to 5 MeV being produced by a high-current industrial electron accelerator. This code includes a geometry package that defines complex quadratic geometries, such as those of the irradiation of products in an irradiation processing facility. In the present case the energy deposited on a water film at the surface of a wood parallelepiped was calculated using the program PENMAIN, which is a generic main program included in the PENELOPE distribution package. The results from the simulation were then compared with measurements performed by irradiating alanine film dosimeters with electrons using a 150 kW Dynamitron electron accelerator. The alanine films were placed on top of a set of wooden planks using the same geometrical arrangement as the one used for the simulation. The way the results from the simulation can be correlated with the actual measurements, taking into account the irradiation parameters, is described. An estimation of the percentage difference between measurements and calculations is also presented.

  8. Investigation of point and extended defects in electron irradiated silicon—Dependence on the particle energy

    SciTech Connect

    Radu, R.; Pintilie, I.; Nistor, L. C.; Fretwurst, E.; Lindstroem, G.; Makarenko, L. F.

    2015-04-28

    This work is focusing on generation, time evolution, and impact on the electrical performance of silicon diodes impaired by radiation induced active defects. n-type silicon diodes had been irradiated with electrons ranging from 1.5 MeV to 27 MeV. It is shown that the formation of small clusters starts already after irradiation with high fluence of 1.5 MeV electrons. An increase of the introduction rates of both point defects and small clusters with increasing energy is seen, showing saturation for electron energies above ∼15 MeV. The changes in the leakage current at low irradiation fluence-values proved to be determined by the change in the configuration of the tri-vacancy (V{sub 3}). Similar to V{sub 3}, other cluster related defects are showing bistability indicating that they might be associated with larger vacancy clusters. The change of the space charge density with irradiation and with annealing time after irradiation is fully described by accounting for the radiation induced trapping centers. High resolution electron microscopy investigations correlated with the annealing experiments revealed changes in the spatial structure of the defects. Furthermore, it is shown that while the generation of point defects is well described by the classical Non Ionizing Energy Loss (NIEL), the formation of small defect clusters is better described by the “effective NIEL” using results from molecular dynamics simulations.

  9. Atomic rearrangements in amorphous Al2O3 under electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Nakamura, R.; Ishimaru, M.; Yasuda, H.; Nakajima, H.

    2013-02-01

    The electron-irradiation-induced crystallization of amorphous Al2O3 (a-Al2O3) was investigated by in-situ transmission electron microscopy under the wide electron-energy region of 25-300 keV. The formation of γ-Al2O3 nanocrystallites was induced by irradiating the a-Al2O3 thin film along with the formation of nanovoids in the crystalline grains regardless of the acceleration voltage. The crystallization became more pronounced with decreasing the electron energy, indicating that electronic excitation processes play a dominant role in the formation of γ-Al2O3. Radial distribution analyses suggested that a-Al2O3 transforms to γ-phase via the "excited" ("stimulated") amorphous state, in which the breaking and rearrangement of unstable short-range Al-O bonds, i.e., fivefold-coordinated Al-O (AlO5) basic units, occur.

  10. Annealing of GaAs solar cells damaged by electron irradiation

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Conway, E. J.

    1978-01-01

    Measurements of thermal annealing of GaAlAs/GaAs solar cells damaged by 1 MeV electron irradiation are reported, and the magnitude of the short-circuit current recovery is discussed. The damaged cells are annealed in a vacuum at 200 C. A cell irradiated at 10 to the 13th power electrons per sq cm recovers all its lost short-circuit current after 15 hours of annealing. Possible application of the annealing process to solar cells in space is also considered.

  11. Temperature, illumination and fluence dependence of current and voltage in electron irradiated solar cells

    NASA Technical Reports Server (NTRS)

    Obenschain, A. F.; Faith, T. J.

    1973-01-01

    Emperical equations have been derived from measurements of solar cell photovoltaic characteristics relating light generated current, IL, and open circuit voltage, VO, to cell temperature, T, intensity of illumination, W, and 1 Mev electron fluence, phi both 2 ohm-cm and 10 ohm-cm cells were tested. The temperature dependency of IL is similar for both resistivities at 140mw/sq cm; at high temperature the coefficient varies with fluence as phi 0.18, while at low temperatures the coefficient is relatively independent of fluence. Fluence dependent degration causes a decrease in IL at a rate proportional to phi 0.153 for both resistivities. At all intensities other than 560 mw/sq cm, a linear dependence of IL on illumination was found. The temperature coefficient of voltage was, to a good approximation, independent of both temperature and illumination for both resistivities. Illumination dependence of VOC was logarithmic, while the decrease with fluence of VOC varied as phi 0.25 for both resistivities.

  12. Effects of electron beam irradiation on the structural properties of polylactic acid/polyethylene blends

    NASA Astrophysics Data System (ADS)

    Bee, Soo-Tueen; Ratnam, C. T.; Sin, Lee Tin; Tee, Tiam-Ting; Wong, Wai-Kien; Lee, Jiuun-Xiang; Rahmat, A. R.

    2014-09-01

    The purpose of this research was to investigate the effects of electron beam irradiation on the properties of polylactic acid (PLA) and low density polyethylene (LDPE) blends. The PLA were compounded with 20-80% LDPE and were exposed to electron beam irradiation dosages of 20-120 kGy. The results from gel content and X-ray diffraction analyses showed that the addition of LDPE to PLA effectively increased the gel content and crystallinity. However, an increasing percentage of LDPE reduced the tensile strength and Young's modulus of the PLA/LDPE samples due to the lower intermolecular bonding of LDPE than of PLA. Moreover, an increase in irradiation dosages gradually decreased the mechanical properties of low-LDPE PLA/LDPE. In contrast, the increasing irradiation dosage enhanced the mechanical properties of higher-LDPE PLA/LDPE. These results indicate that higher amounts of LDPE effectively react with the release of free radicals within the amorphous phase if the blends are subjected to irradiation. The higher amounts of free radicals induce the formation of three-dimensional cross-linked networks in the polymer matrix and thus increase the gel content. The irradiation-induced cross-linking in PLA/LDPE samples improves the mechanical properties and crystallinity by promoting a structural rearrangement of the polymer matrix into a highly ordered structure.

  13. Water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels

    NASA Astrophysics Data System (ADS)

    Wang, Qingguo; Zhou, Xue; Zeng, Jinxia; Wang, Jizeng

    2016-02-01

    In this paper, the electron beam irradiation technology being more suitable for the industry application is explored to fabricate the acrylic acid (AAc) monomer-grafted polyvinyl alcohol (PVA-g-AAc) hydrogels. ATR-IR spectra of the PVA-g-AAc hydrogels shows an obvious absorption peak of the sbnd Cdbnd O group at 1701 cm-1, indicating that the AAc monomers were grafted onto the PVA macromolecules. This paper also studied some effects of the mass ratio of PVA/AAc, pH of buffer solution and irradiation dosage on the water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels. The water swelling ratio of PVA-g-AAc hydrogels decreases with increased irradiation dosage and mass ratio of PVA/AAc, whereas swelling ratio increases with increased pH of buffer solution and soaking time. The water-swelling behavior of PVA-g-AAc hydrogels occurred easily in an alkaline environment, particularly in a buffer solution with pH 9.2. Both PVA-g-AAc hydrogels (PVA/AAc = 1/5, w/w) irradiated with 5 kilogray (kGy) and PVA-g-AAc hydrogels (PVA/AAc = 1/1, w/w) irradiated with 15 kGy could easily absorb water and lead to high water swelling ratios (up to about 600%), which are potential candidates to meet the requirements for some biomedical applications.

  14. Characterization of electron-irradiated biaxially-oriented polypropylene films

    SciTech Connect

    Hammoud, A.N.; Laghari, J.R.; Krishnakumar, B.

    1988-06-01

    Post-radiation changes in the electrical and mechanical properties of capacitor-grade isotactic polypropylene films exposed to electron radiation were reported in a previous paper. Based on the data obtained, it was suggested that crosslinking, chain scission and oxidative degradation were responsible for the radiation-induced changes in the film. In the present investigations, additional electrical characterizations that included the dc breakdown voltage and ac conductivity measurements were performed. Effects of the electron radiation on the physical and chemical properties were also evaluated so as to identify the actual degradation mechanisms. These studies included scanning electron microscopy, X-ray diffraction, infrared spectroscopy and sol gel measurements. The results obtained confirm that crosslinking and chain scission of the polymer are responsible for the changes in the lower dose range, whereas oxidative degradation become predominant at higher dose levels.

  15. The assessment of microscopic charging effects induced by focused electron and ion beam irradiation of dielectrics.

    PubMed

    Stevens-Kalceff, Marion A; Levick, Katie J

    2007-03-01

    Energetic beams of electrons and ions are widely used to probe the microscopic properties of materials. Irradiation with charged beams in scanning electron microscopes (SEM) and focused ion beam (FIB) systems may result in the trapping of charge at irradiation induced or pre-existing defects within the implanted microvolume of the dielectric material. The significant perturbing influence on dielectric materials of both electron and (Ga(+)) ion beam irradiation is assessed using scanning probe microscopy (SPM) techniques. Kelvin Probe Microscopy (KPM) is an advanced SPM technique in which long-range Coulomb forces between a conductive atomic force probe and the silicon dioxide specimen enable the potential at the specimen surface to be characterized with high spatial resolution. KPM reveals characteristic significant localized potentials in both electron and ion implanted dielectrics. The potentials are observed despite charge mitigation strategies including prior coating of the dielectric specimen with a layer of thin grounded conductive material. Both electron- and ion-induced charging effects are influenced by a delicate balance of a number of different dynamic processes including charge-trapping and secondary electron emission. In the case of ion beam induced charging, the additional influence of ion implantation and nonstoichiometric sputtering from compounds is also important. The presence of a localized potential will result in the electromigration of mobile charged defect species within the irradiated volume of the dielectric specimen. This electromigration may result in local modification of the chemical composition of the irradiated dielectric. The implications of charging induced effects must be considered during the microanalysis and processing of dielectric materials using electron and ion beam techniques.

  16. Optical and electron beam studies of gamma-irradiated AlGaN/GaN high-electron-mobility transistors

    NASA Astrophysics Data System (ADS)

    Yadav, Anupama; Glasscock, Cameron; Flitsiyan, Elena; Chernyak, Leonid; Lubomirsky, Igor; Khodorov, Sergey; Salzman, Joseph; Meyler, Boris; Coppola, Carlo; Guay, Sebestian; Boivin, Jasques

    2016-03-01

    The impact of 60Co gamma-irradiation on n-channel AlGaN/GaN high-electron-mobility transistors was studied by means of temperature-dependent electron beam-induced current (EBIC) and cathodoluminescence (CL) techniques. For the doses up to ∼250 Gy, an enhancement of minority carrier transport was observed as evident from the EBIC measurements. This enhancement is associated with internal electron irradiation induced by the primary gamma photons. For the doses above ∼250 Gy, deterioration in minority carrier transport was explained by carrier scattering on radiation-induced defects. It is shown that calculated activation energy from the EBIC and CL measurements follows exactly the same trend, which implies that the same underlying phenomenon is responsible for observed findings.

  17. Increasing Electronic Nose Recognition Ability by Laser Irradiation

    NASA Astrophysics Data System (ADS)

    Alejandra, Massacane; Juan, Vorobioff; Karina, Pierpauli; Norberto, Boggio; Silvia, Reich; Carlos, Rinaldi; Alfredo, Boselli; Alberto, Lamagna; Laura, Azcárate M.; Jorge, Codnia; Francisco, Manzano

    2009-05-01

    We present a method to increase the capability of an electronic nose to discriminate between a priori similar odours. We analyze the case of olive oil because it is well known that the characteristics of its aroma impair in many cases the discrimination between different kinds of olive oils especially when they are from similar geographic regions. In the present work we study how to improve the electronic nose performance for the above mentioned discrimination by the use of two IR laser wavelengths for vaporization.

  18. In-situ observation of xenon nanocrystals in aluminum under electron and ion irradiation in transmission electron microscope.

    SciTech Connect

    Furuya, K.

    1998-11-11

    In-situ ion irradiation in the transmission electron microscope (TEM) is one of the unique techniques to investigate the structural evolution of materials induced by particle bombardments. In spite of many efforts to get clear results from in-situ ion irradiation, the results were sometimes unclear because of physical and technical problems associated with TEM and ion beam hardwares. This paper describes a newly developed ion beam interface with an ultra-high voltage TEM (HVTEM) for in-situ observation of ion implantation of metals and alloys in atomic scale.

  19. Low-energy electron irradiation of preheated and gas-exposed single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ecton, P. A.; Beatty, J.; Verbeck, G.; Lakshantha, W.; Rout, B.; Perez, J. M.

    2016-11-01

    We investigate the conditions under which electron irradiation at 2 keV of single-wall carbon nanotube (SWCNT) bundles produces an increase in the Raman D peak. We find that irradiation of SWCNTs that are preheated in situ at 600 °C for 1 h in ultrahigh vacuum before irradiation does not result in an increase in the D peak. Irradiation of SWCNTs that are preheated in vacuum and then exposed to air or gases results in an increase in the D peak, suggesting that adsorbates play a role in the increase in the D peak. Small diameter SWCNTs that are not preheated or preheated and then exposed to air show a significant increase in the D and G bands after irradiation. X-ray photoelectron spectroscopy shows no chemical shifts in the C 1s peak of SWCNTs that have been irradiated versus SWCNTs that have not been irradiated, suggesting that chemisorption of adsorbates is not responsible for the increase in the D peak.

  20. Influence of electron beam irradiation on growth of Phytophthora cinnamomi and its control in substrates

    NASA Astrophysics Data System (ADS)

    MigdaŁ, Wojciech; Orlikowski, Leszek B.; Ptaszek, Magdalena; Gryczka, Urszula

    2012-08-01

    Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5 kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10 kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15 kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10 kGy. Irradiation of the horticultural substrates did not affect plant growth.

  1. Improving enzymatic hydrolysis of industrial hemp ( Cannabis sativa L.) by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Shin, Soo-Jeong; Sung, Yong Joo

    2008-09-01

    The electron beam irradiation was applied as a pretreatment of the enzymatic hydrolysis of hemp biomass with doses of 150, 300 and 450 kGy. The higher irradiation dose resulted in the more extraction with hot-water extraction or 1% sodium hydroxide solution extraction. The higher solubility of the treated sample was originated from the chains scission during irradiation, which was indirectly demonstrated by the increase of carbonyl groups as shown in diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectra. The changes in the micro-structure of hemp resulted in the better response to enzymatic hydrolysis with commercial cellulases (Celluclast 1.5L and Novozym 342). The improvement in enzymatic hydrolysis by the irradiation was more evident in the hydrolysis of the xylan than in that of the cellulose.

  2. Electron Spin Resonance Investigation of Free Radicals Produced in Pulverized Non-Irradiated Sugar

    NASA Astrophysics Data System (ADS)

    Thamaphat, K.; Limsuwan, P.; Smith, S. M.

    An electron spin resonance (ESR) study of the effects of pulverization on non-irradiated crystalline sugar was performed. It indicated that the crystalline sugar before being ground did not give any ESR signal but an ESR signal was found in pulverized sugar. These results implied that free radicals were produced by pulverization. Moreover, the free radical density increased as the particle size decreased. From high-performance liquid chromatography analysis and the ESR spectrum of non-irradiated powdered sucrose, it can be inferred that the pulverization-induced free radical in sugar is a sucrose radical. Recently, many researchers have reported that sugar irradiated with 60Co γ-rays at different doses produced stable sucrose radicals. This may imply that the process of sucrose radical formation by mechanical stress is similar to that for irradiation.

  3. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    NASA Astrophysics Data System (ADS)

    Yang, Shen; Cai, Jie; Lv, Peng; Zhang, Conglin; Huang, Wei; Guan, Qingfeng

    2015-09-01

    The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO3 solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  4. An improved approach to identify irradiated spices using electronic nose, FTIR, and EPR spectroscopy.

    PubMed

    Sanyal, Bhaskar; Ahn, Jae-Jun; Maeng, Jeong-Hwan; Kyung, Hyun-Kyu; Lim, Ha-Kyeong; Sharma, Arun; Kwon, Joong-Ho

    2014-09-01

    Changes in cumin and chili powder from India resulting from electron-beam irradiation were investigated using 3 analytical methods: electronic nose (E-nose), Fourier transform infrared (FTIR) spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The spices had been exposed to 6 to 14 kGy doses recommended for microbial decontamination. E-nose measured a clear difference in flavor patterns of the irradiated spices in comparison with the nonirradiated samples. Principal component analysis further showed a dose-dependent variation. FTIR spectra of the samples showed strong absorption bands at 3425, 3007 to 2854, and 1746 cm(-1). However, both nonirradiated and irradiated spice samples had comparable patterns without any noteworthy changes in functional groups. EPR spectroscopy of the irradiated samples showed a radiation-specific triplet signal at g = 2.006 with a hyper-fine coupling constant of 3 mT confirming the results obtained with the E-nose technique. Thus, E-nose was found to be a potential tool to identify irradiated spices. PMID:25155212

  5. Effects of electron beam irradiation on the microbial growth and quality of beef jerky during storage

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Chun, Ho-Hyun; Song, Hyeon-Jeong; Song, Kyung-Bin

    2010-11-01

    Electron beam irradiation was applied to improve the microbial safety of beef jerky during storage. Beef jerky samples were irradiated at doses of 1, 3, 5, and 10 kGy and stored at 20 °C for 60 d. Microbiological data indicated that the populations of total aerobic bacteria significantly decreased with increasing irradiation dosage. In particular, the populations of total aerobic bacteria were significantly decreased by 1.76 log CFU/g at 10 kJ/m 2, compared to the control. Color measurements showed reduced Hunter L and a values of beef jerky for all the treatments during storage, and the Hunter L, a, and b values of beef jerky were not significantly different among the treatments. Sensory evaluation results also showed that electron beam irradiation did not affect sensory scores in overall during storage. Therefore, the results suggest that electron beam irradiation could be useful in improving the microbial safety without impairing the quality of beef jerky during storage.

  6. An improved approach to identify irradiated spices using electronic nose, FTIR, and EPR spectroscopy.

    PubMed

    Sanyal, Bhaskar; Ahn, Jae-Jun; Maeng, Jeong-Hwan; Kyung, Hyun-Kyu; Lim, Ha-Kyeong; Sharma, Arun; Kwon, Joong-Ho

    2014-09-01

    Changes in cumin and chili powder from India resulting from electron-beam irradiation were investigated using 3 analytical methods: electronic nose (E-nose), Fourier transform infrared (FTIR) spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The spices had been exposed to 6 to 14 kGy doses recommended for microbial decontamination. E-nose measured a clear difference in flavor patterns of the irradiated spices in comparison with the nonirradiated samples. Principal component analysis further showed a dose-dependent variation. FTIR spectra of the samples showed strong absorption bands at 3425, 3007 to 2854, and 1746 cm(-1). However, both nonirradiated and irradiated spice samples had comparable patterns without any noteworthy changes in functional groups. EPR spectroscopy of the irradiated samples showed a radiation-specific triplet signal at g = 2.006 with a hyper-fine coupling constant of 3 mT confirming the results obtained with the E-nose technique. Thus, E-nose was found to be a potential tool to identify irradiated spices.

  7. A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate

    DOE PAGES

    Liu, Peng; Zhang, Yanwen; Xue, Haizhou; Jin, Ke; Crespillo, Miguel L.; Wang, Xuelin; Weber, William J.

    2016-01-09

    Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss, themore » velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.« less

  8. Comparison of gamma ray and electron beam irradiation on extraction yield, morphological and antioxidant properties of polysaccharides from tamarind seed

    NASA Astrophysics Data System (ADS)

    Choi, Jong-il; Kim, Jae-Kyung; Srinivasan, Periasamy; Kim, Jae-Hun; Park, Hyun-Jin; Byun, Myung-Woo; Lee, Ju-Woon

    2009-07-01

    Tamarind ( Tamarindus indica L) seed polysaccharide (TSP) is of great important due to its various biological activities. The present investigation was carried out to compare extraction yield, morphological characteristics, average molecular weights and antioxidant activities of TSP from gamma- and electron beam (EB)-irradiated tamarind kernel powder. The tamarind kernel powder was irradiated with 0, 5 and 10 kGy by gamma ray (GR) and electron beam, respectively. The extraction yield of TSP was increased significantly by EB and GR irradiation, but there was no significant difference between irradiation types. Morphological studies by scanning electron microscope showed that TSP from GR-irradiated tamarind seed had a fibrous structure, different from that of EB irradiated with a particle structures. The average molecular weight of TSP was decreased by the irradiation, and EB treatment degraded more severely than GR. Superoxide radical scavenging ability and total antioxidant capacity of EB-treated TSP showed higher than those of GR-treated TSP.

  9. Additive effects of electronic and nuclear energy losses in irradiation-induced amorphization of zircon

    SciTech Connect

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-28

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. We found that taking the electronic energy loss out as a friction term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.

  10. Additive effects of electronic and nuclear energy loss in irradiation-induced amorphization of zircon

    DOE PAGES

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-29

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. As a result, we found that taking the electronic energy loss out as a frictionmore » term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.« less

  11. Additive effects of electronic and nuclear energy loss in irradiation-induced amorphization of zircon

    SciTech Connect

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-29

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. As a result, we found that taking the electronic energy loss out as a friction term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.

  12. Effect of heavy-ion and electron irradiation on properties of Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Konczykowski, Marcin

    2013-03-01

    The introduction of defects by particle irradiation is used to reveal the role of disorder in matter, which is unavoidable in all crystalline solids. In superconductors defects introduce flux pinning, controlling critical current, Jc; as well as pair-breaking scattering, limiting the critical temperature, Tc. To elucidate defect related properties of Fe-based superconductors (FBS) we precede in two types of irradiation: heavy ion (6GeV Pb) to create disorder in the form of amorphous tracks and low temperature electron irradiation (2.5MeV at 20K) to create point like defects. Substantial increase of irreversible magnetization and an upward shift of the irreversibility line are observed after heavy ion irradiation of all FBS investigated to date. In BaK 122 , signatures of a Bose-glass vortex state; angular dependence and variable-range hopping flux creep are revealed. Remarkably, heavy ion irradiation does not depress Tc, however, point-like disorder introduced by electron irradiation does substantially. In isovalently substituted Ba(FeAs1 - xPx) 2 and Ba(Fe1 - x Rux As) 2 crystals, Tc decreases linearly with dose. Suppression to 40 % of initial value of Tc was achieved in Ba(FeAs1 - xPx) 2 . An increase of normal state resistivity is observed and correlated to depression of Tc. Change of superconducting gap structure with disorder was determined from penetration depth measurements, λ (T) dependence, at various stages of irradiation. Linear in T variation of pristine samples, indicative of the presence of nodes in gap, turned at low irradiation dose to exponential T variation, indicative of a fully gaped state. T2 variation of λ is observed at higher doses. This behaviour is incompatible with symmetry-imposed nodes of d-wave pairing but consistent with S + / - , S + / + mechanisms. This is the first observation of the impurity-induced node lifting expected in anisotropic s-wave superconductors

  13. Temperature dependences of the electron phonon coupling, electron heat capacity and thermal conductivity in Ni under femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Lin, Zhibin; Zhigilei, Leonid V.

    2007-05-01

    The electron temperature dependences of the electron-phonon coupling factor, electron heat capacity and thermal conductivity are investigated for Ni in a range of temperatures typically realized in femtosecond laser material processing applications, from room temperature up to temperatures of the order of 10 4 K. The analysis is based on the electronic density of states obtained through the electronic structure calculations. Thermal excitation of d band electrons is found to result in a significant decrease in the strength of the electron-phonon coupling, as well as large deviations of the electron heat capacity and the electron thermal conductivity from the commonly used linear temperature dependences on the electron temperature. Results of the simulations performed with the two-temperature model demonstrate that the temperature dependence of the thermophysical parameters accounting for the thermal excitation of d band electrons leads to higher maximum lattice and electron temperatures achieved at the surface of an irradiated Ni target and brings the threshold fluences for surface melting closer to the experimentally measured values as compared to the predictions obtained with commonly used approximations of the thermophysical parameters.

  14. Virus inactivation studies using ion beams, electron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Smolko, Eduardo E.; Lombardo, Jorge H.

    2005-07-01

    Known methods of virus inactivation are based on the chemical action of some substances such as acetylethylenimine, betapropiolactone, glycidalaldehyde, formaldehyde, etc. In such a process, the viral suspension should be kept at room or higher temperatures for 24-48 h. Under these conditions, physical and chemical agents act to degrade the virus antigenic proteins. On the contrary with ionizing radiations at low temperatures, the treatment does not cause such degradation allowing the study of different viral functions. In this work, particle (α, d and ß) and γ irradiations were used for partial and total inactivation of Foot and Mouth Disease Virus (FMDV), Rauscher Leukemia Virus (RLV) and Herpes Simplex Virus (HSV). Obtention of the D37 dose from survival curves and the application of the target theory, permitted the determination of molecular weight of the nucleic acid genomes, EBR values and useful information for vaccine preparation. For RLV virus, a two target model of the RNA genome was deduced in accordance with biological information while from data from the literature and our own work on the structure of the scrapie prion, considering the molecular weight obtained by application of the theory, a new model for prion replication is presented, based on a trimer molecule.

  15. Reduction of 1/f noise in graphene after electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Zahid Hossain, Md.; Rumyantsev, Sergey; Shur, Michael S.; Balandin, Alexander A.

    2013-04-01

    We investigated experimentally the effect of the electron-beam irradiation on the level of the low-frequency 1/f noise in graphene devices. It was found that 1/f noise in graphene reduces with increasing concentration of defects induced by irradiation. The increased amount of structural disorder in graphene under irradiation was verified with micro-Raman spectroscopy. The bombardment of graphene devices with 20-keV electrons reduced the noise spectral density, SI/I2 (I is the source-drain current) by an order-of magnitude at the radiation dose of 104 μC/cm2. We analyzed the observed noise reduction in the limiting cases of the mobility and carrier number fluctuation mechanisms. The obtained results are important for the proposed graphene applications in analog, mixed-signal, and radio-frequency systems, integrated circuits and sensors.

  16. Influence of electron irradiation on properties of semi-insulating GaAs detectors

    NASA Astrophysics Data System (ADS)

    Šagátová, Andrea; Zaťko, Bohumír; Sedlačková, Katarína; Pavlovič, Márius; Nečas, Vladimír

    2015-03-01

    The effects of electron beam irradiation on electrical and spectrometric properties of semi-insulating (SI) GaAs detectors were studied. The electric properties were monitored by reverse and forward current-voltage characteristics. In general, a breakdown voltage decrease with the dose was observed. However, some samples showed a local increase in the breakdown voltage at doses between 5 and 10 kGy. The detector spectrometric properties (the charge collection efficiency (CCE), the energy resolution and the detection efficiency) were evaluated from measured spectra of the 241Am radionuclide gamma source before and after electron irradiation. The CCE and energy resolution showed minor changes after irradiation. The detection efficiency noticed an initial increase (up to a dose of 5 kGy) followed by a permanent decrease. At 30 kGy, the overall degradation of detector functionality was observed with all samples.

  17. Void and precipitate structure in ion- and electron-irradiated ferritic alloys

    NASA Astrophysics Data System (ADS)

    Ohnuki, Soumei; Takahashi, Heishichiro; Takeyama, Taro

    1984-05-01

    Void formation and precipitation were investigated in Fe10Cr and Fe13Cr base alloys by 200 keV C + ion and 1 MeV electron irradiation. The ferritic alloys exhibited significant resistance to void swelling. In FeCr and FeCr-Si alloys, ion-irradiation produced the precipitates of M 23C 6 type. In the FeCrTi alloy, Ti-rich precipitates were formed with high number density on {100} plane. During electron-irradiation Fe-10Cr alloy, complex dislocation loops were produced with high number density, of which Burgers vector was mostly <100>. EDX analysis showed slightly enrichment of chromium on dislocation loops. These results suggested that the stability of <100> type dislocation structure at high dose is an important factor on good swelling resistance in the ferritic alloys, moreover, titanium addition will intensify the stability of the doslocations through the fine precipitation on dislocations.

  18. Microstructural, thermal and antibacterial properties of electron beam irradiated Bombyx mori silk fibroin films

    SciTech Connect

    Asha, S.; Sanjeev, Ganesh; Sangappa; Naik, Prashantha; Chandra, K. Sharat

    2014-04-24

    The Bombyx mori silk fibroin (SF) films were prepared by solution casting method and the effects of electron beam on structural, thermal and antibacterial responses of the prepared films were studied. The electron irradiation for different doses was carried out using 8 MeV Microtron facility at Mangalore University. The changes in microstructural parameters and thermal stability of the films were investigated using Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Both microstructuralline parameters (crystallite size and lattice strain (g in %)) and thermal stability of the irradiated films have increased with radiation dosage. Agar diffusion method demonstrated the antibacterial activity of SF film which was increased after irradiation on both Gram-positive and Gram-negative species.

  19. Effect of defects produced by electron irradiation on the electrical properties of graphene

    NASA Astrophysics Data System (ADS)

    Balan, Adrian; Rodriguez-Manzo, Julio Alejandro; Puster, Matthew; Drndic, Marija

    2015-03-01

    We present a study of the effects of the defects produced by electron irradiation on the electrical and crystalline properties of graphene. We realized back or side gated electrical devices from monolayer graphene crystals suspended on a 50nm SiNx. The devices are exposed to electron irradiation inside a 200kV transmission electron microscope (TEM) and we perform in situ conductance measurements. The number of defects and the quality of the crystalline network obtained by diffraction are correlated with the observed decrease in mobility and conductivity of the devices. We observe a different behavior between type of monolayer materials, and try to associate with different conduction with defect models. [1] Towards sensitive graphene nanoribbon-nanopore devices by preventing electron beam induced damage. M. Puster, J. A. Rodriguez- Manzo, A. Balan, M. Drndic. ACS Nano,10.1021/nn405112m.

  20. Dissipative electronic transport through double quantum dots irradiated with microwaves

    NASA Astrophysics Data System (ADS)

    Brandes, Tobias; Aguado, Ramon; Platero, Gloria

    2003-03-01

    Double quantum dots in the strong Coulomb blockade regime are realizations of two-level systems defined from two tunnel--splitted ground states, which are separated by a large energy gap from the remaining many--particle states. The interactions between electrons and bosonic degrees of freedom (photons, phonons) in these systems can be tested and manipulated in electronic transport experiments [1]. Monochromatic classical radiation (AC fields, microwaves) gives rise to various non-linear effects such as photo-sidebands or dynamical localization (coherent supression of tunneling) that show up in the time-averaged, stationary electronic current [2]. On the other hand, quantum noise of a dissipative environment strongly influences the transport properties of coupled quantum dots [3,4]. In this contribution, we quantitatively investigate the combined influence of a classical, monochromatic time-dependent AC field and a dissipative boson environment on the non-linear transport through a double quantum dot. We develop a Floquet-like theory [5] that takes into account the effect of the electron reservoirs (leads) and can be numerically evaluated for arbitrary strong AC fields and arbitrary boson environment. In limiting cases we reproduce previous analytical results (polaron tunneling, Tien-Gordon formula). [1] T. Fujisawa, T. H. Oosterkamp, W. G. van der Wiel, B. W. Broer, R. Aguado, S. Tarucha, and L. P. Kouwenhoven, Science 282, 932 (1998); R. H. Blick, D. Pfannkuche, R. J. Haug, K. v. Klitzing, and K. Eberl, Phys. Rev. Lett. 80, 4032 (1998). [2] T. H. Stoof, Yu. V. Nazarov, Phys. Rev. B 53, 1050 (1996). [3] T. Brandes, B. Kramer, Phys. Rev. Lett. 83, 3021 (1999); T. Brandes, F. Renzoni, R. H. Blick, Phys. Rev. B 64, 035319 (2001); T. Brandes, T. Vorrath, Phys. Rev. B 66, 075341 (2002). [4] R. Aguado and L. P. Kouwenhoven, Phys. Rev. Lett, 84, 1986 (2000). [5] M. Grifoni, P. Hänggi, Phys. Rep. 304, 229 (1998).

  1. Characterization of an Irradiated RERTR-7 Fuel Plate Using Transmission Electron Microscopy

    SciTech Connect

    J. Gan; D. D. Keiser, Jr.; B. D. Miller; A. B. Robinson; P. Medvedev

    2010-03-01

    Transmission electron microscopy (TEM) has been used to characterize an irradiated fuel plate with Al-2Si matrix from the RERTR-7 experiment that was irradiated under moderate reactor conditions. The results of this work showed the presence of a bubble superlattice within the U-7Mo grains that accommodated fission gases (e.g., Xe). The presence of this structure helps the U-7Mo exhibit a stable swelling behaviour during irradiation. Furthermore, TEM analysis showed that the Si-rich interaction layers that develop around the fuel particles at the U-7Mo/matrix interface during fuel plate fabrication and irradiation become amorphous during irradiation, and in regions of the interaction layer that have relatively high Si concentrations the fission gas bubbles remain small and contained within the layer but in areas with lower Si concentrations the bubbles grow in size. An important question that remains to be answered about the irradiation behaviour of U-Mo dispersion fuels, is how do more aggressive irradiation conditions affect the behaviour of fission gases within the U-7Mo fuel particles and in the amorphous interaction layers on the microstructural scale that can be characterized using TEM? This paper discusses the results of TEM analysis that was performed on a sample taken from an irradiated RERTR-7 fuel plate with Al-2Si matrix. This plate was exposed to more aggressive irradiation conditions than was the sample taken from the RERTR-6 plate. The microstructural features present within the U-7Mo and the amorphous interaction layers will be discussed. The results of this analysis will be compared to what was observed in the earlier RERTR-6 fuel plate characterization.

  2. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    NASA Astrophysics Data System (ADS)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-01

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  3. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    SciTech Connect

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-23

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  4. Ultraviolet and electron irradiation of DC-704 siloxane oil in zinc orthotitanate paint

    SciTech Connect

    Mossman, D.L.; Barsh, M.K.; Greenberg, S.A.

    1982-01-01

    Discrepancies exist between accelerated laboratory simulation and geosynchronous orbit flight data for zinc orthotitanate (ZOT) paint degradation. The effects of ultraviolet and electron irradiation on ZOT contaminated with DC-704 silicone oil are reported. In-situ solar absorptance and emittance changes for contaminated and clean specimens are discussed with reference to post-test surface morphology, determined by scanning electron microscope analysis. Features of the contaminated ZOT degradation kinetics correlate with orbital performance.

  5. Improved radiation resistant properties of electron irradiated c-Si solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Khuram; Khan, Sohail A.; MatJafri, M. Z.

    2016-08-01

    This work investigates the radiation tolerance of c-Si solar cells under electron energy of 9 MeV with fluence of 5.09×1016 cm-2. The solar cells were fabricated and characterized before and after electron irradiation through current-voltage (I-V), capacitance-voltage (C-V), and frequency dependent conductance (Gp) measurements. The results revealed that all the output parameters such as short circuit current (Isc), open circuit voltage (Voc), series resistance (Rs), and efficiency (η) were degraded after electron irradiation. Capacitance-Voltage measurements show that there is a slight decrease in the base carrier concentration (ND), while a small increase in depletion layer width (WD) was due to an increase in the base carrier concentration. Enhancements in the density of interface states (Nss), and trap time constant (τ) have been observed after electron irradiation. The results has revealed that back surface field (BSF) solar cell with front surface passivation (FSP) presented lowest efficiency degradation ratio of 11.3% as compared to 15.3% of the solar cell without FSP. The subsequent annealing of irradiated Si solar cell devices revealed that the Si solar cell with FSP demonstrated high efficiency recovery ratio of 94% as compared to non-FSP solar cell.

  6. In-situ observations of point-defect precipitation at dislocations in electron-irradiated silver

    SciTech Connect

    Jenkins, M.L.; Hardy, G.J.; Kirk, M.A.

    1986-09-01

    In-situ weak-beam observations of the development of electron irradiation damage at dislocations in silver are described. Dislocations constrict and promote in their vicinity the formation of stacking-fault tetrahedra. The possibility that these are of interstitial nature is discussed.

  7. A study on the microstructural parameters of 550 keV electron irradiated Lexan polymer films

    SciTech Connect

    Hareesh, K.; Pramod, R.; Petwal, V. C.; Dwivedi, Jishnu; Sangappa; Sanjeev, Ganesh

    2012-06-05

    Lexan polymer films irradiated with 550 keV Electron Beam (EB) were characterized using Wide Angle Xray Scattering (WAXS) data to study the microstructural parameters. The crystal imperfection parameters like crystal size , lattice strain (g in %) and enthalpy ({alpha}) have been determined by Line Profile Analysis (LPA) using Fourier method of Warren.

  8. Formation of Alumina Nanocapsules by High-Energy-Electron Irradiation of Na-dawsonite Nanorods

    PubMed Central

    Duan, Xiaochuan; Kim, Tongil; Han, Lili; Ma, Jianmin; Du, Xiwen; Zheng, Wenjun

    2013-01-01

    We report the synthesis of unique Al2O3 nanocapsules by high-energy-electron irradiation of Na-dawsonite and a formation mechanism different from thermal decomposition which usually produces NaAlO2. The novel decomposition process may open up a shortcut for fabricating hollow nanostructures. PMID:24225738

  9. Effect of electron irradiation on the 3C-4H transformation in a Co-Fe alloy

    SciTech Connect

    Allen, C.W.; Mori, H.

    1996-03-01

    Preliminary results are presented of a study of electron irradiation on the martensitic transformation in a relatively dilute terminal solid solution of Co+5.75 wt% Fe. The experiments demonstrate qualitatively the profound effect that the damage structure produced by electron irradiation can have on these simple martensitic transformations. Further study is being pursued to attempt to quantify the transformation retardation effect.

  10. Monte Carlo simulation on a gold nanoparticle irradiated by electron beams.

    PubMed

    Chow, James C L; Leung, Michael K K; Jaffray, David A

    2012-06-01

    This study investigated the secondary electron production from a gold nanoparticle (GNP) irradiated by monoenergetic electron beams using Monte Carlo (MC) simulation. Spherical GNPs with diameters of 2, 50 and 100 nm in water were irradiated by monoenergetic electron beams with energies equal to 50 keV, 250 keV, 1 MeV and 4 MeV. MC simulations were performed using the Geant4 toolkit to determine the energy of the secondary electrons emitted from the GNPs. The mean effective range and deflection angle of the secondary electrons were tracked. Energy depositions inside and outside the nanoparticles due to the secondary electrons were also calculated. For comparisons, simulations were repeated by replacing the GNPs with water. Our results show that the mean effective range of secondary electrons increased with an increase of the GNP size and electron beam energy. For the electron beam energy and GNP size used in this study, the mean effective range was 0.5-15 µm outside the nanoparticle, which is approximately within the dimension of a living cell. The mean deflection angles varied from 78 to 83 degrees as per our MC results. The proportion of energy deposition inside the GNP versus that outside increased with the GNP size. This is different from the results obtained from a previous study using photon beams. The secondary electron energy deposition ratio (energy deposition for GNP/energy deposition for water) was found to be highest for the smallest GNP of 2 nm diameter in this study. For the energy deposited by the secondary electron, we concluded that the addition of GNPs can increase the secondary electron energy deposition in water, though most of the energy was self-absorbed by the large nanoparticles (50 and 100 nm). In addition, an electron source in the presence of GNPs does not seem to be better than photons as the yield of secondary electrons per unit mass of gold is less than water.

  11. Electron Beam Irradiation Dose Dependently Damages the Bacillus Spore Coat and Spore Membrane

    PubMed Central

    Fiester, S. E.; Helfinstine, S. L.; Redfearn, J. C.; Uribe, R. M.; Woolverton, C. J.

    2012-01-01

    Effective control of spore-forming bacilli begs suitable physical or chemical methods. While many spore inactivation techniques have been proven effective, electron beam (EB) irradiation has been frequently chosen to eradicate Bacillus spores. Despite its widespread use, there are limited data evaluating the effects of EB irradiation on Bacillus spores. To study this, B. atrophaeus spores were purified, suspended in sterile, distilled water, and irradiated with EB (up to 20 kGy). Irradiated spores were found (1) to contain structural damage as observed by electron microscopy, (2) to have spilled cytoplasmic contents as measured by spectroscopy, (3) to have reduced membrane integrity as determined by fluorescence cytometry, and (4) to have fragmented genomic DNA as measured by gel electrophoresis, all in a dose-dependent manner. Additionally, cytometry data reveal decreased spore size, increased surface alterations, and increased uptake of propidium iodide, with increasing EB dose, suggesting spore coat alterations with membrane damage, prior to loss of spore viability. The present study suggests that EB irradiation of spores in water results in substantial structural damage of the spore coat and inner membrane, and that, along with DNA fragmentation, results in dose-dependent spore inactivation. PMID:22319535

  12. Effects of proton and electron irradiation on the structural and tribological properties of MoS 2/polyimide

    NASA Astrophysics Data System (ADS)

    Liu, Baixing; Pei, Xianqiang; Wang, Qihua; Sun, Xiaojun; Wang, Tingmei

    2011-11-01

    To study the structural and tribological properties of MoS2/polyimide (MoS2/PI) composite under the irradiation environment of proton and electron, the MoS2/PI composites were investigated in a ground-based simulation facility, in which the energy of proton and electron was 25 keV and the flux was 2.5 × 1014 cm-2 s-1. The experimental results revealed that the simplex and combined irradiation of proton and electron induced bond break and cross-link, proton irradiation can break the PI bond easier than electron irradiation and then formed the graphite-like structure at surface area of the samples. Irradiation decreased the friction coefficient and wear rate remarkably of the composites comparing with the pristine one. The wear rate increased with the increasing of the proton and combined radiation time, and decreased with the electron radiation conditions.

  13. Identification of irradiated wheat by germination test, DNA comet assay and electron spin resonance

    NASA Astrophysics Data System (ADS)

    Barros, Adilson C.; Freund, Maria Teresa L.; Villavicencio, Ana Lúcia C. H.; Delincée, Henry; Arthur, Valter

    2002-03-01

    In several countries, there has been an increase in the use of radiation for food processing thus improving the quality and sanitary conditions, inhibiting pathogenic microorganisms, delaying the natural aging process and so extending product lifetime. The need to develop analytical methods to detect these irradiated products is also increasing. The goal of this research was to identify wheat irradiated using different radiation doses. Seeds were irradiated with a gamma 60Co source (Gammacell 220 GC) in the Centro de Energia Nuclear na Agricultura and the Instituto de Pesquisas Energéticas e Nucleares. Dose rate used were 1.6 and 5.8kGy/h. Applied doses were 0.0, 0.10, 0.25, 0.50, 0.75, 1.0, and 2.0kGy. After irradiation, seeds were analysed over a 6 month period. Three different detection methods were employed to determine how irradiation had modified the samples. Screening methods consisted of a germination test measuring the inhibition of shooting and rooting and analysis of DNA fragmentation. The method of electron spin resonance spectroscopy allowed a better dosimetric evaluation. These techniques make the identification of irradiated wheat with different doses possible.

  14. Effect of electron beam irradiation on forensic evidence. 2. Analysis of writing inks on porous surfaces.

    PubMed

    Ramotowski, Robert S; Regen, Erin M

    2007-05-01

    The effect of electron beam irradiation on a series of different writing inks is described. As the anthrax-tainted letters were discovered in October 2001, the U.S. government began to experiment with the use of the electron beam irradiation process for destroying such biological agents. Plans initially considered a large-scale countrywide use of this technology. However, over time the scope of this plan as well as the radiation dosage were reduced, especially when some adverse consequences to mailed items subjected to this process were observed. Little data existed at the time to characterize what level of damage might be expected to occur with common items sent through the mail. This was especially important to museums and other institutions that routinely ship valuable and historic items through the mail. Although the Smithsonian Institution initiated some studies of the effect of electron beam irradiation on archived materials, little data existed on the effect that this process would have on forensic evidence. Approximately 97 different black, blue, red, green, and yellow writing inks were selected. Writing ink types included ballpoint, gel, plastic/felt tip, and rollerball. All noncontrol samples were subjected to standard mail irradiation conditions used by the U.S. Postal Service at the time this experiment was performed. A video spectral comparator and thin-layer chromatography (TLC) analysis were used to evaluate both the control and the irradiated samples. Some published studies reported changes in the presence/absence of dye bands in the chromatograms of irradiated writing inks. Some of these studies report the formation of additional dye bands on the chromatogram while others report missing dye bands. However, using standard testing guidelines and procedures, none of the 97 irradiated inks tested were found to show any significant optical or chemical differences from the control samples. In addition, random testing of some of the ink samples using a

  15. Effect of electron beam irradiation on forensic evidence. 2. Analysis of writing inks on porous surfaces.

    PubMed

    Ramotowski, Robert S; Regen, Erin M

    2007-05-01

    The effect of electron beam irradiation on a series of different writing inks is described. As the anthrax-tainted letters were discovered in October 2001, the U.S. government began to experiment with the use of the electron beam irradiation process for destroying such biological agents. Plans initially considered a large-scale countrywide use of this technology. However, over time the scope of this plan as well as the radiation dosage were reduced, especially when some adverse consequences to mailed items subjected to this process were observed. Little data existed at the time to characterize what level of damage might be expected to occur with common items sent through the mail. This was especially important to museums and other institutions that routinely ship valuable and historic items through the mail. Although the Smithsonian Institution initiated some studies of the effect of electron beam irradiation on archived materials, little data existed on the effect that this process would have on forensic evidence. Approximately 97 different black, blue, red, green, and yellow writing inks were selected. Writing ink types included ballpoint, gel, plastic/felt tip, and rollerball. All noncontrol samples were subjected to standard mail irradiation conditions used by the U.S. Postal Service at the time this experiment was performed. A video spectral comparator and thin-layer chromatography (TLC) analysis were used to evaluate both the control and the irradiated samples. Some published studies reported changes in the presence/absence of dye bands in the chromatograms of irradiated writing inks. Some of these studies report the formation of additional dye bands on the chromatogram while others report missing dye bands. However, using standard testing guidelines and procedures, none of the 97 irradiated inks tested were found to show any significant optical or chemical differences from the control samples. In addition, random testing of some of the ink samples using a

  16. Effects of Electron-Beam Irradiation on Buccal-Cell DNA

    PubMed Central

    Castle, Philip E.; Garcia-Closas, Montserrat; Franklin, Tracie; Chanock, Stephen; Puri, Vinita; Welch, Robert; Rothman, Nathaniel; Vaught, Jim

    2003-01-01

    Buccal cells were collected from 29 participants, by use of mouthwash rinses, and were split into equal aliquots, with one aliquot irradiated by electron-beam (E-beam) irradiation equivalent to the sterilizing dosage used by the U.S. Postal Service and the other left untreated. Aliquots were extracted and tested for DNA yields (e.g., TaqMan assay for quantifying human genomic DNA), genomic integrity, and amplification-based analysis of genetic variants (e.g., single-nucleotide polymorphisms [SNPs] and single tandem repeats [STRs]). Irradiated aliquots had lower median DNA yields (3.7 μg/aliquot) than untreated aliquots (7.6 μg/aliquot) (P<.0005) and were more likely to have smaller maximum DNA fragment size, on the basis of genomic integrity gels, than untreated aliquots (P<.0005). Irradiated aliquots showed poorer PCR amplification of a 989-bp β-globin target (97% for weak amplification and 3% for no amplification) than untreated aliquots (7% for weak amplification and 0% for no amplification) (P<.0005), but 536-bp and 268-bp β-globin targets were amplified from all aliquots. There was no detectable irradiation effect on SNP assays, but there was a significant trend for decreased detection of longer STRs (P=.01) in irradiated versus untreated aliquots. We conclude that E-beam irradiation reduced the yield and quality of buccal-cell specimens, and, although irradiated buccal-cell specimens may retain sufficient DNA integrity for some amplified analyses of many common genomic targets, assays that target longer DNA fragments (>989 bp) or require whole-genome amplification may be compromised. PMID:12917795

  17. Direct observation of the structural and electronic changes of Li{sub 2}MnO{sub 3} during electron irradiation

    SciTech Connect

    Phillips, Patrick J.; Klie, Robert F.; Iddir, Hakim; Abraham, Daniel P.

    2014-09-15

    This study focuses on the effects of electron beam induced irradiation to the layered oxide Li{sub 2}MnO{sub 3}. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy are used to characterize structural and electronic transitions in the material during irradiation, with a focus on changes in Mn valence and O content. This truly in situ irradiation allows for specific particle tracking, dose quantification, and real-time observation, while demonstrating many parallels to the oxide's structure evolution observed during electrochemical cycling. Furthermore, it is demonstrated that typical imaging conditions are not severe enough to induce damage to the pristine oxide.

  18. Measurements of the energy spectrum of electrons emanating from solid materials irradiated by a picosecond laser

    SciTech Connect

    Di Stefano, C. A. Kuranz, C. C.; Thomas, A. G. R.; Drake, R. P.; Keiter, P. A.; Rasmus, A. M.; Wan, W. C.; Joglekar, A. S.; McKelvey, A.; Zhao, Z.; Klein, S. R.; Seely, J. F.; Williams, G. J.; Park, J.; Chen, H.; Kemp, G. E.; MacDonald, M. J.; Pereira, N. R.; Jarrott, L. C.; Peebles, J.; and others

    2015-04-15

    In this work, we present the results of experiments observing the properties of the electron stream generated laterally when a laser irradiates a metal. We find that the directionality of the electrons is dependent upon their energies, with the higher-energy tail of the spectrum (∼1 MeV and higher) being more narrowly focused. This behavior is likely due to the coupling of the electrons to the electric field of the laser. The experiments are performed by using the Titan laser to irradiate a metal wire, creating the electron stream of interest. These electrons propagate to nearby spectator wires of differing metals, causing them to fluoresce at their characteristic K-shell energies. This fluorescence is recorded by a crystal spectrometer. By varying the distances between the wires, we are able to probe the divergence of the electron stream, while by varying the medium through which the electrons propagate (and hence the energy-dependence of electron attenuation), we are able to probe the energy spectrum of the stream.

  19. Irradiator to study damage induced to large nonvolatile molecules by low-energy electrons

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Cloutier, Pierre; Wagner, J. Richard; Sanche, Léon

    2004-11-01

    We report on the design and performance of an irradiator to study the fragmentation of large nonvolatile molecules induced by low-energy electron impact under ultrahigh vacuum. The apparatus consists essentially of a new type of electron gun which can bombard molecules spin-coated on the inside surface of a cylinder. With this configuration, it is possible to irradiate a relatively large area (26 cm2) of a solid molecular film and thus, produce a sufficient amount of degraded material for subsequent analysis, outside vacuum, of the compounds remaining on the inner surface of the cylinder. The electron energy is tunable from 3 to 130±0.5 eV and the current density adjustable up to 2.6±0.5×1012 electron s-1 cm-2, respectively. Choosing thymidine as a model system for deoxyribose nucleic acid damage, we show that nonvolatile fragments produced by 5-100 eV electron irradiation can be characterized by high-pressure liquid chromatography/ultraviolet detector and gas chromatography/mass spectroscopy.

  20. Raman Shifts in Electron-Irradiated Monolayer MoS2.

    PubMed

    Parkin, William M; Balan, Adrian; Liang, Liangbo; Das, Paul Masih; Lamparski, Michael; Naylor, Carl H; Rodríguez-Manzo, Julio A; Johnson, A T Charlie; Meunier, Vincent; Drndić, Marija

    2016-04-26

    We report how the presence of electron-beam-induced sulfur vacancies affects first-order Raman modes and correlate the effects with the evolution of the in situ transmission-electron microscopy two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a red-shift in the E' Raman peak and a less pronounced blue-shift in the A'1 peak with increasing electron dose. Using energy-dispersive X-ray spectroscopy and selected-area electron diffraction, we show that irradiation causes partial removal of sulfur and correlate the dependence of the Raman peak shifts with S vacancy density (a few %). This allows us to quantitatively correlate the frequency shifts with vacancy concentration, as rationalized by first-principles density functional theory calculations. In situ device current measurements show an exponential decrease in channel current upon irradiation. Our analysis demonstrates that the observed frequency shifts are intrinsic properties of the defective systems and that Raman spectroscopy can be used as a quantitative diagnostic tool to characterize MoS2-based transport channels.

  1. Flexible cadmium telluride thin films grown on electron-beam-irradiated graphene/thin glass substrates

    SciTech Connect

    Seo, Won-Oh; Kim, Jihyun; Koo, Yong Hwan; Kim, Byungnam; Lee, Byung Cheol; Kim, Donghwan

    2014-08-25

    We demonstrate the close-spaced sublimation growth of polycrystalline cadmium telluride (CdTe) thin films on a flexible graphene electrode/thin glass substrate structure. Prior to the growth of CdTe films, chemical-vapor-deposited graphene was transferred onto a flexible glass substrate and subjected to electron-beam irradiation at an energy of 0.2 MeV in order to intentionally introduce the defects into it in a controlled manner. Micro-Raman spectroscopy and sheet resistance measurements were employed to monitor the damage and disorder in the electron-beam irradiated graphene layers. The morphology and optical properties of the CdTe thin films deposited on a graphene/flexible glass substrate were systematically characterized. The integration of the defective graphene layers with a flexible glass substrate can be a useful platform to grow various thin-film structures for flexible electronic and optoelectronic devices.

  2. Time-dependent charge distributions in polymer films under electron beam irradiation

    SciTech Connect

    Yasuda, Masaaki; Kainuma, Yasuaki; Kawata, Hiroaki; Hirai, Yoshihiko; Tanaka, Yasuhiro; Watanabe, Rikio; Kotera, Masatoshi

    2008-12-15

    The time-dependent charge distribution in polymer film under electron beam irradiation is studied by both experiment and numerical simulation. In the experiment, the distribution is measured with the piezoinduced pressure wave propagation method. In the simulation, the initial charge distribution is obtained by the Monte Carlo method of electron scattering, and the charge drift in the specimen is simulated by taking into account the Poisson equation, the charge continuity equation, Ohm's law, and the radiation-induced conductivity. The results obtained show that the negative charge deposited in the polymer film, whose top and bottom surfaces are grounded, drifts toward both grounded electrodes and that twin peaks appear in the charge distribution. The radiation-induced conductivity plays an important role in determining the charge distribution in the polymer films under electron beam irradiation.

  3. Effects of electron-beam irradiation on some mechanical properties of polymer films

    NASA Astrophysics Data System (ADS)

    Żenkiewicz, M.

    2004-04-01

    Effect of the electron-beam irradiation on the tensile strength at break, elongation at break, and tear resistance for packaging films made of low-density polyethylene (LDPE), biaxially oriented polypropylene (BOPP), and polyethylene terephthalate (PET) is discussed. The measurements in both the machine direction and the transverse direction were made. It was found that the electron irradiation caused an increase in the tear resistance of the LDPE film when doses of up to 100 kGy were applied. A significant decrease and even loss of the tear resistance of the films of BOPP and, partially, PET were observed at doses already below 25 kGy. This indicates that the BOPP and PET films when modified with the electron radiation can hardly be used in packaging.

  4. Ageing and thermal recovery of paramagnetic centers induced by electron irradiation in yttria-stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Costantini, J. M.; Beuneu, F.

    We have used electron spin resonance spectroscopy to study the defects induced in yttria-stabilized zirconia (YSZ) single crystals by 2.5-MeV electron irradiations. Two paramagnetic centers are produced: the first one with an axial <111> symmetry is similar to the trigonal Zr3+ electron center (T center) found after X-ray irradiation or thermo-chemical reduction, whereas the second one is a new oxygen hole center with an axial <100> symmetry different from the orthorhombic O- center induced by X-ray irradiation. At a fluence around 10(18) e/cm(2) , both centers are bleached out near 600 K, like the corresponding X-ray induced defects. At a fluence around 10(19) e/cm(2) , defects are much more stable, since complete thermal bleaching occurs near 1000 K. Accordingly, ageing of as-irradiated samples shows that high-dose defects at more stable than the low-dose ones.

  5. Hardening and microstructural evolution of A533b steels irradiated with Fe ions and electrons

    NASA Astrophysics Data System (ADS)

    Watanabe, H.; Arase, S.; Yamamoto, T.; Wells, P.; Onishi, T.; Odette, G. R.

    2016-04-01

    Radiation hardening and embrittlement of A533B steels is heavily dependent on the Cu content. In this study, to investigate the effect of copper on the microstructural evolution of these materials, A533B steels with different Cu levels were irradiated with 2.4 MeV Fe ions and 1.0 MeV electrons. Ion irradiation was performed from room temperature (RT) to 350 °C with doses up to 1 dpa. At RT and 290 °C, low dose (<0.1 dpa) hardening trend corresponded with ΔH ∝ (dpa)n, with n initially approximately 0.5 and consistent with a barrier hardening mechanism, but saturating at ≈0.1 dpa. At higher dose levels, the radiation-induced hardening exhibited a strong Cu content dependence at 290 °C, but not at 350 °C. Electron irradiation using high-voltage electron microscopy revealed the growth of interstitial-type dislocation loops and enrichment of Ni, Mn, and Si in the vicinities of pre-existing dislocations at doses for which the radiation-induced hardness due to ion irradiation was prominent.

  6. Oil palm empty fruit bunch (OPEFB) fiber reinforced PVC/ENR blend-electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Ratnam, Chantara Thevy; Raju, Gunasunderi; Yunus, Wan Md Zin Wan

    2007-12-01

    The effect of irradiation on the tensile properties of oil palm empty fruit bunch (OPEFB) fiber reinforced poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blend using HAAKE Rheomixer at 150 °C. The composites were then irradiated by using a 3.0 MeV electron beam machine at doses ranging from 0 to 100 kGy in air and room temperature. The tensile strength, Young's modulus, elongation at break and gel fraction of the composites were measured. Comparative studies were also made by using poly(methyl acrylate) grafted OPEFB fiber in the similar blend system. An increase in tensile strength, Young's modulus and gel fraction, with a concurrent reduction in the elongation at break (Eb) of the PVC/ENR/OPEFB composites were observed upon electron beam irradiation. Studies revealed that grafting of the OPEFB fiber with methyl acrylate did not cause appreciable effect to the tensile properties and gel fraction of the composites upon irradiation. The morphology of fractured surfaces of the composites, examined by a scanning electron microscope showed an improvement in the adhesion between the fiber and the matrix was achieved upon grafting of the fiber with methyl acrylate.

  7. Evaluation of the hazard from exposure to electron irradiation simulating that in the synchronous orbit

    NASA Technical Reports Server (NTRS)

    Lippincott, S. W.; Foelsche, T.; Montour, J. L.; Bender, R.; Wilson, I. J.

    1972-01-01

    The electron spectrum predicted for the synchronous orbit was simulated to determine the effects that might occur to astroscientists exposed to such irradiation while on a prolonged space station mission in that region. Miniature pigs were exposed to monoenergetic and spectral-fractionated irradiations with 0.5 to 2.1 MeV electrons. Clinical and pathological alterations observed in biopsies were correlated with depth-dose pattern and length of post irradiation period up to one year. With monoenergetic electrons, the lowest dose causing a recognizable lesion was 1450 rad and with increasing dose lesions appeared earlier and were more severe. At the highest dose given, 2650 rad, ulceration extending into the dermis was present by twenty one days and required about four months for complete healing. Spectral-fractionated irradiations, in which the total dose range was essentially comparable to that of the monoenergetic series, resulted in very minimal outer dermis edema at 1790 rad and at no dose employed did necrosis of epidermis or ulceration into dermis occur.

  8. Remediation of groundwater polluted with chlorinated ethylenes by ozone-electron beam irradiation treatment.

    PubMed

    Gehringer, P; Proksch, E; Eschweiler, H; Szinovatz, W

    1992-09-01

    OH radicals formed in water radiolysis may be effectively used for the oxidative decomposition of trichloroethylene and perchloroethylene contained as micropollutants in groundwater. Addition of ozone to the water before irradiation causes the reducing species of the water radiolysis to be converted into OH radicals. Moreover, this eliminates the dose rate effect observed with irradiation alone. By the ozone-electron beam treatment greater than 95% of the organic chlorine content are mineralized, only negligible amounts of organic chlorine containing by-products are formed. AMES test has shown no mutagenic activity at all.

  9. Influence of electron beam irradiation on structural and optical properties of α-Ag2WO4 nanoparticles.

    PubMed

    A, Sreedevi; K P, Priyanka; K K, Babitha; S, Ganesh; Varghese, T

    2016-09-01

    The influence of 8MeV electron beam irradiation on the structural and optical properties of silver tungstate (α-Ag2WO4) nanoparticles synthesized by chemical precipitation method was investigated. The dose dependent effect of electron irradiation was investigated by various characterization techniques such as, X-ray diffraction, scanning electron microscopy, UV-vis absorption spectroscopy, photoluminescence and Raman spectroscopy. Systematic studies confirm that electron beam irradiation induces non-stoichiometry, defects and particle size variation on α-Ag2WO4, which in turn results changes in optical band gap, photoluminescence spectra and Raman bands.

  10. Dose dependent electrical and structural properties of BiFeO{sub 3} nanoparticles under electron irradiation

    SciTech Connect

    Rao, Prashanth K. S.; Krishnan, Sheeja; Pattabi, Manjunatha; Sanjeev, Ganesh

    2015-06-24

    The paper deals with the effect of electron irradiation on the structural and electrical properties of BiFeO{sub 3} nanoparticles synthesized by standard sol-gel method. The samples were subjected to electron irradiation using a Microtron accelerator. The effects of irradiation on structural morphology viz grain size, microstrain and dislocation have been studied by X-ray diffraction (XRD). The current density of the samples at various doses of high energy electrons was also studied. It was observed that electrical conductivity depends on electron dose.

  11. Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation

    PubMed Central

    Pang, Dalong; Nico, Jeffrey S.; Karam, Lisa; Timofeeva, Olga; Blakely, William F.; Dritschilo, Anatoly; Dizdaroglu, Miral; Jaruga, Pawel

    2014-01-01

    In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base–sugar combinations (e.g. 8,5′-cyclopurine-2′-deoxynucleosides) and DNA–protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0–80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous 252Cf decay fissions. 8-hydroxy-2′-deoxyguanosine (8-OH-dG), (5′R)-8,5′-cyclo-2′-deoxyadenosine (R-cdA) and (5′S)-8,5′-cyclo-2′-deoxyadenosine (S-cdA) were quantified using liquid chromatography–isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET 252Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation. PMID:25034731

  12. Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine

    SciTech Connect

    Rodriguez-Fernandez, Luis

    2010-09-10

    Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

  13. A multiscale method for the analysis of defect behavior in MO during electron irradiation

    SciTech Connect

    Rest, J.; Insepov, Z.; Ye, B.; Yun, D.

    2014-10-01

    In order to overcome a lack of experimental information on values for key materials properties and kinetic coefficients, a multiscale modeling approach is applied to defect behavior in irradiated Mo where key materials properties, such as point defect (vacancy and interstitial) migration enthalpies as well as kinetic factors such as dimer formation, defect recombination, and self interstitial–interstitial loop interaction coefficients, are obtained by molecular dynamics calculations and implemented into rate-theory simulations of defect behavior. The multiscale methodology is validated against interstitial loop growth data obtained from electron irradiation of pure Mo. It is shown that the observed linear behavior of the loop diameter vs. the square root of irradiation time is a direct consequence of the 1D migration of self-interstitial atoms.

  14. Effect of electron irradiation in vacuum on FEP-A silicon solar cell covers

    NASA Technical Reports Server (NTRS)

    Marsik, S. J.; Broder, J. D.

    1975-01-01

    Fluorinated ethylene-propylene-A (FEP-A) covers on silicon solar cells were irradiated with 1-MeV electrons, in vacuum, to an accumulated fluence equivalent to approximately 28 years in synchronous orbit. The effect of irradiation on the light transmittance of FEP-A was checked by measuring the short-circuit current of the cells after each dose increment. The results indicate no apparent overall loss in transmission due to irradiation of FEP-A. Filter wheel measurements revealed some darkening of the FEP-A at the blue end of the spectrum. Although no delamination from the cell surface was observed while in vacuum, embrittlement of FEP-A occurred at the accumulated dose.

  15. Electron beam irradiation induces abnormal development and the stabilization of p53 protein of American serpentine leafminer, Liriomyza trifolii (Burgess)

    NASA Astrophysics Data System (ADS)

    Koo, Hyun-Na; Yun, Seung-Hwan; Yoon, Changmann; Kim, Gil-Hah

    2012-01-01

    The American serpentine leafminer fly, Liriomyza trifolii (Burgess), is one of the most destructive polyphagous pests worldwide. In this study, we determined electron beam doses for inhibition of normal development of the leaf miner and investigated the effect of electron beam irradiation on DNA damage and p53 stability. Eggs (0-24 h old), larvae (2nd instar), puparia (0-24 h old after pupariation) and adults (24 h after emergence) were irradiated with increasing doses of electron beam irradiation (six levels between 30 and 200 Gy). At 150 Gy, the number of adults that developed from irradiated eggs, larvae and puparia was lower than in the untreated control. Fecundity and egg hatchability decreased depending on the doses applied. Reciprocal crosses between irradiated and unirradiated flies demonstrated that males were more radiotolerant than females. Adult longevity was not affected in all stages. The levels of DNA damage in L. trifolii adults were evaluated using the alkaline comet assay. Our results indicate that electron beam irradiation increased levels of DNA damage in a dose-dependent manner. Moreover, low doses of electron beam irradiation led to the rapid appearance of p53 protein within 6 h; however, it decreased after exposure to high doses (150 Gy and 200 Gy). These results suggest that electron beam irradiation induced not only abnormal development and reproduction but also p53 stability caused by DNA damage in L. trifolii. We conclude that a minimum dose of 150 Gy should be sufficient for female sterilization of L. trifolii.

  16. Effects of intraoperative electron irradiation in the dog on cell turnover in intact and surgically-anastomosed aorta and intestine

    SciTech Connect

    Sindelar, W.F.; Morrow, B.M.; Travis, E.L.; Tepper, J.; Merkel, A.B.; Kranda, K.; Terrill, R.

    1983-04-01

    Adults dogs were subjected to laparotomy and intraoperative electron irradiation after division and reanastomosis of aorta or after construction of a blind loop of small intestine having a transverse suture line and an end-to-side anastomosis. Dogs received intraoperative irradiation of both intact and anastomosed aorta or intestine in doses of 0, 2000, 3000, or 4500 rad. Animals were sacrificed at seven days or three months following treatment. At 24 hours prior to sacrifice, dogs received 5 mCi tritiated thymidine intravenously. Irradiated and non-irradiated segments of aorta and small intestine, including intact and anastomotic regions, were analyzed for tritiated thymidine incorporation and were subjected to autoradiography. Incorporation studies showed diminution in tritiated thymidine uptake by irradiated portions of aorta and small intestine, in both intact and anastomotic regions. Autoradiograms revealed that irradiated areas of intact or anastomotic aorta or intestine had diminished labeling of stromal cells, suggesting a lowered cell proliferative capacity of irradiated tissue compared to non-irradiated portions. Inflammatory cells showed similar labeling indices in irradiated and non-irradiated tissues, both intact and surgically-manipulated, suggesting that irradiation does not significantly affect a subsequent local inflammatory response. Radiation-induced decreases in tritiated thymidine incoporation in irradiated aorta and small intestine were generally more marked at seven days than at three months following irradiation, suggesting that radiation-induced depression of cell turnover rates decreases with time.

  17. Effect of electron beam irradiation on developmental stages of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

    NASA Astrophysics Data System (ADS)

    Kim, Junheon; Chung, Soon-Oh; Jang, Sin Ae; Jang, Miyeon; Park, Chung Gyoo

    2015-07-01

    Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), is an economically important and polyphagous pest, which harms various kinds of food crops and important agricultural plants, such as cotton and paprika. Effects of electron beam irradiation at six dose levels between 50 and 350 Gy on the egg (24-48 h old), the larval (4-5th instar), and the pupal (7-d old for female, 5-d old for male) development, and on the adult (1-d old) reproduction were tested to identify a potential quarantine treatment dose. Increased doses of irradiation on eggs decreased egg hatchability, pupation and adult emergence and increased larval period. ED99 values for inhibition of hatching, pupation and emergence were 460.6, 236.9 and 197.8 Gy, respectively. When larvae were irradiated with more than 280 Gy, no larvae could develop into pupae. ED99 values for inhibition of pupation and adult emergence were 265.6 and 189.6 Gy, respectively. Even though the irradiation on pupa did not completely inhibit adult emergence, most of the pupae emerged to deformed adults. When adults were irradiated, fecundity was not affected. However, F1 egg hatching was completely inhibited at the dose of 350 Gy. ED99 value for inhibition of adult emergence was estimated at 366.5 Gy. Our results suggest that electron beam irradiation could be recommendable as an alternative to MB and as a phytosanitary treatment for quarantine. A treatment dose of less than or equal to 220 Gy is suggested as a potential quarantine treatment to H. armigera egg for prevention of pupation and to larva for prevention of adult emerge.

  18. Raman shifts in electron-irradiated monolayer MoS2

    DOE PAGES

    Parkin, William M.; Balan, Adrian; Liang, Liangbo; Das, Paul Masih; Lamparski, Michael; Naylor, Carl H.; Rodríguez-Manzo, Julio A.; Johnson, A. T. Charlie; Meunier, Vincent; Drndic, Marija

    2016-03-21

    Here, we report how the presence of electron-beam-induced sulfur vacancies affects first-order Raman modes and correlate the effects with the evolution of the in situ transmission-electron microscopy (TEM) two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a redshift in the E Raman peak and a less pronounced blueshift in the A'1 peak with increasing electron dose. Using energy-dispersive X-ray spectroscopy (EDS), we show that irradiation causes partial removal of sulfur and correlate the dependence of the Raman peak shifts with S vacancy density (a few %), which is confirmed by first-principles density functional theory calculations. In situ devicemore » current measurements show exponential decrease in channel current upon irradiation. Our analysis demonstrates that the observed frequency shifts are intrinsic properties of the defective systems and that Raman spectroscopy can be used as a quantitative diagnostic tool to characterize MoS2-based transport channels.« less

  19. Influence of electron beam irradiation on mechanical and thermal properties of polypropylene/polyamide blend

    SciTech Connect

    Nakamura, Shigeya; Tokumitsu, Katsuhisa

    2014-05-15

    The effects of electron beam irradiation on the mechanical and thermal properties of polypropylene (PP) and polyamide6 (PA6) blends-with talc 20 wt% as filler, SEBS-g-MAH as compatibilizer, and triallyl isocyanurate as crosslinking agent-were investigated. Although the tensile and flexural moduli and strengths of the PP/PA6 blends with talc, SEBS-g-MAH, and TAIC could be increased by the application of electron beam irradiation, the impact strength was decreased. Ddifferential scanning calorimetryer measurements showed that the melting temperatures of all PP/PA6 blends were decreased with increases in the electron beam irradiationdose. From dynamic mechanical analyzer results, a storage modulus curve in the plateau region was observed only in the PP/PA6 blends with talc, SEBS-g-MAH, and TAIC; the storage modulus increased with increasing electron beam irradiation dose, indicating that the three-dimensional network developed gradually in the more amorphous PA6. As a result, the most significant improvement observed in heat distortion tests under high load (1.8 MPa) occurred at 200 kGy.

  20. Ionic liquids influence on the surface properties of electron beam irradiated wood

    NASA Astrophysics Data System (ADS)

    Croitoru, Catalin; Patachia, Silvia; Doroftei, Florica; Parparita, Elena; Vasile, Cornelia

    2014-09-01

    In this paper, the influence of three imidazolium-based ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-hexyl-3-methylimidazolium chloride) on the structure and surface properties of sycamore maple (Acer pseudoplatanus) veneers submitted to electron beam irradiation with a dose of 50 kGy has been studied by using Fourier transform infrared spectroscopy, as well as image, scanning electron microscopy/SEM/EDX, atomic force microscopy and contact angle analysis. The experimental results have proven that the studied ionic liquids determine a better preservation of the structural features of wood (cellulose crystallinity index and lignin concentration on the surface) as well as some of surface properties such as surface energy, roughness, color upon irradiation with electron beam, in comparison with the reference wood, but surface composition is changed by treatment with imidazolium-based ionic liquids mainly with 1-butyl-3-methylimidazolium tetrafluoroborate. Also, under electron beam irradiation covalent bonding of the imidazolium moiety to wood determines a higher resistance to water penetration and spreading on the surface.

  1. An in situ transmission electron microscopy study of the ion irradiation induced amorphisation of silicon by He and Xe

    DOE PAGES

    Edmondson, P. D.; Abrams, K. J.; Hinks, J. A.; Greaves, G.; Pawley, C. J.; Hanif, I.; Donnelly, S. E.

    2015-11-21

    We used transmission electron microscopy with in situ ion irradiation to examine the ion-beam-induced amorphisation of crystalline silicon under irradiation with light (He) and heavy (Xe) ions at room temperature. Analysis of the electron diffraction data reveal the heterogeneous amorphisation mechanism to be dominant in both cases. Moreover, for the differences in the amorphisation curves are discussed in terms of intra-cascade dynamic recovery, and the role of electronic and nuclear loss mechanisms.

  2. Electron spin resonance studies of free radicals in gamma-irradiated soybean paste.

    PubMed

    Lee, E J; Volkov, V I; Lee, C H

    2001-07-01

    Free radicals in gamma-irradiated soybean paste were investigated by electron spin resonance (ESR) spectroscopy to determine the effect of temperature (77-296 K) and moisture content (1-54%) of samples irradiated at high dose (1-40 kGy). The samples were kept in liquid nitrogen (77 K) during irradiation and subsequent ESR measurements. The spectra shown at 77 K consisted of the hydrogen atom lines at low and high field and complicated symmetric spectrum. By increasing the microwave power, the line shape of ESR spectra altered, which indicated the detection of different paramagnetic centers at different microwave powers. In saturation curves, it was possible to select four types of spectra components which were different in their relaxation times. By the different irradiation doses, the change in free radical concentration showed a curvilinearly increasing relationship with irradiation dose in wet samples, whereas a proportional relationship was observed with dried samples. This might indicate that the indirect process of free radical formation was involved with the existence of free water radicals in the wet samples.

  3. Effects of neutron irradiation on strength of fusion reactor materials and their electron beam welded joints

    NASA Astrophysics Data System (ADS)

    Kaga, S.; Tamura, T.; Yoshida, H.; Miyata, K.

    1991-03-01

    Several aluminum alloys (A7N01, A5083 and A6061) and a ferritic martensitic steel (JFMS) were used in the present study of the effects of neutron irradiation on the strength of base materials and their electron beam welded joints. Neutron irradiation tests were performed using the core irradiation facility at Kyoto University Reactor (KUR). Neutron fluences were 2.0 × 10 22 9.1 × 10 22 and 1.7 × 10 23n/ m2 ( E > 0.1 MeV). Tensile tests were performed at 4.2, 77 and 293 K on miniature specimens prepared from both the base and welded materials. Aluminum alloys exhibit serrations in the nominal stress-nominal strain curve at 4.2 K. Little effect of neutron irradiation on the serration is observed. The ductility decrease of base metal and welded joints of aluminum alloys by neutron irradiation is smaller than that of JFMS. JFMS, especially welded joints, showed strong radiation embrittlement at cryogenic temperatures.

  4. Effect of annealing on electronic carrier transport properties of gamma-irradiated AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Yadav, Anupama; Schwarz, Casey; Shatkhin, Max; Wang, Luther; Flitsiyan, Elena; Chernyak, Leonid; Liu, Lu; Hwang, Ya; Ren, Fan; Pearton, Stephen; Department of Physics, University of Central Florida Collaboration; Department of Chemical Engineering, University of Florida Collaboration; Department of Materials Science; Engineering, University of Florida Collaboration

    2014-03-01

    AlGaN/GaN High Electron Mobility Transistors were irradiated with 60Co gamma-ray doses from 100Gy to 1000Gy, in order to analyze the effects of irradiation on the devices' transport properties. Temperature dependent Electron Beam Induced Current (EBIC) measurements, conducted on the devices before and after exposure to gamma-irradiation, allowed for the obtaining of activation energy related to radiation-induced defects due to nitrogen vacancies. Later, the devices were annealed at 200o C for 25 minutes. All the measurements were performed again to study the effect of annealing on the gamma-irradiated devices. Annealing of gamma-irradiated transistors shows that partial recovery of device performance is possible at this temperature. DC current-voltage measurements were also conducted on the transistors to assess the impact of gamma-irradiation and annealing on transfer, gate and drain characteristics.

  5. Use of electron beam irradiation to improve the microbiological safety of Hippophae rhamnoides

    NASA Astrophysics Data System (ADS)

    Minea, R.; Nemţanu, M. R.; Manea, S.; Mazilu, E.

    2007-09-01

    Sea buckthorn ( Hippophae rhamnoides) is increasingly used in food supplements due to its dietary and medicinal compounds with a beneficial role in human diet and health. As many other medicinal plants, sea buckthorn can be contaminated with microorganisms which exerts an important impact on the overall quality of the products. Irradiation is an effective method for food preservation because it is able to destroy pathogenic microorganisms keeping the organoleptic and nutritional characteristics of the foods. The objective of the present study was to investigate the application of electron beam irradiation in order to improve the microbiological safety of sea buckthorn. The experimental results indicated that the electron beam treatment might be a good method to remove undesirable microorganisms from sea buckthorn without significant changes in its active principles.

  6. Study of defects in electron irradiated CuInSe{sub 2} by positron lifetime spectroscopy

    SciTech Connect

    Polity, A.; Krause-Rehberg, R.; Staab, T.E.; Puska, M.J.; Klais, J.; Moeller, H.J.; Meyer, B.K.

    1998-01-01

    CuInSe{sub 2} was studied in the as-grown state and after low-temperature (4 K) 2 MeV electron irradiation. The positron bulk lifetime of 235 ps was measured for the unirradiated sample. The positron bulk lifetime was theoretically calculated and is in good agreement with the experimental value. In addition, the defect-related lifetimes for mono-, di-, and trivacancies are theoretically determined. An increased average positron lifetime indicated after electron irradiation the appearance of open-volume defects, most probably of divacancy type. The disappearance of this defect was observed during annealing below 250 K. Other defects were formed leading to a divacancy signal at least stable up to 600 K in the temperature range above 450 K. {copyright} {ital 1998 American Institute of Physics.}

  7. New green polymeric composites based on hemp and natural rubber processed by electron beam irradiation.

    PubMed

    Stelescu, Maria-Daniela; Manaila, Elena; Craciun, Gabriela; Dumitrascu, Maria

    2014-01-01

    A new polymeric composite based on natural rubber reinforced with hemp has been processed by electron beam irradiation and characterized by several methods. The mechanical characteristics: gel fraction, crosslink density, water uptake, swelling parameters, and FTIR of natural rubber/hemp fiber composites have been investigated as a function of the hemp content and absorbed dose. Physical and mechanical properties present a significant improvement as a result of adding hemp fibres in blends. Our experiments showed that the hemp fibers have a reinforcing effect on natural rubber similar to mineral fillers (chalk, carbon black, silica). The crosslinking rates of samples, measured using the Flory-Rehner equation, increase as a result of the amount of hemp in blends and the electron beam irradiation dose increasing. The swelling parameters of samples significantly depend on the amount of hemp in blends, because the latter have hydrophilic characteristics.

  8. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    NASA Astrophysics Data System (ADS)

    Sathyanarayana Bhat, P.; Rao, Asha; Sanjeev, Ganesh; Usha, G.; Priya, G. Krishna; Sankaran, M.; Puthanveettil, Suresh E.

    2015-06-01

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5-100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance-frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 -1016 cm-3.

  9. Movement of basal plane dislocations in GaN during electron beam irradiation

    SciTech Connect

    Yakimov, E. B.; Vergeles, P. S.; Polyakov, A. Y.; Lee, In-Hwan; Pearton, S. J.

    2015-03-30

    The movement of basal plane segments of dislocations in low-dislocation-density GaN films grown by epitaxial lateral overgrowth as a result of irradiation with the probing beam of a scanning electron microscope was detected by means of electron beam induced current. Only a small fraction of the basal plane dislocations was susceptible to such changes and the movement was limited to relatively short distances. The effect is explained by the radiation enhanced dislocation glide for dislocations pinned by two different types of pinning sites: a low-activation-energy site and a high-activation-energy site. Only dislocation segments pinned by the former sites can be moved by irradiation and only until they meet the latter pinning sites.

  10. Behavior of nanocrystalline Xe precipitates in Al under 1 MeV electron irradiation.

    SciTech Connect

    Allen, C. W.; Birtcher, R. C.; Donnelly, S. E.; Furuya, K.; Mitsuishi, K.; Song, M.

    1999-03-10

    Crystalline nanoprecipitates of Xe have been produced by ion implantation into high purity Al at 300 K. With an off-zone axis TEM imaging technique, the nanocrystals may be clearly structure imaged against a nearly featureless background. Under the 1 MeV electron irradiation employed for the HREM observation, Xe nanocrystals exhibit a number of readily observed physical phenomena including migration within the matrix, changes in shape, faulting, melting, crystallization and coalescence. The various phenomena observed as changes in the Xe nanocrystals reflect changes of matrix cavity-surface structure. The Xe nanocrystal thus allows investigation indirectly into changes in interface morphology at the atomic level, resulting in this instance from electron irradiation damage. Such changes have heretofore been inaccessible to observation.

  11. Calculation of dose contributions of electron and charged heavy particles inside phantoms irradiated by monoenergetic neutron.

    PubMed

    Satoh, Daiki; Takahashi, Fumiaki; Endo, Akira; Ohmachi, Yasushi; Miyahara, Nobuyuki

    2008-09-01

    The radiation-transport code PHITS with an event generator mode has been applied to analyze energy depositions of electrons and charged heavy particles in two spherical phantoms and a voxel-based mouse phantom upon neutron irradiation. The calculations using the spherical phantoms quantitatively clarified the type and energy of charged particles which are released through interactions of neutrons with the phantom elements and contribute to the radiation dose. The relative contribution of electrons increased with an increase in the size of the phantom and with a decrease in the energy of the incident neutrons. Calculations with the voxel-based mouse phantom for 2.0-MeV neutron irradiation revealed that the doses to different locations inside the body are uniform, and that the energy is mainly deposited by recoil protons. The present study has demonstrated that analysis using PHITS can yield dose distributions that are accurate enough for RBE evaluation. PMID:18580044

  12. New Green Polymeric Composites Based on Hemp and Natural Rubber Processed by Electron Beam Irradiation

    PubMed Central

    Stelescu, Maria-Daniela; Craciun, Gabriela; Dumitrascu, Maria

    2014-01-01

    A new polymeric composite based on natural rubber reinforced with hemp has been processed by electron beam irradiation and characterized by several methods. The mechanical characteristics: gel fraction, crosslink density, water uptake, swelling parameters, and FTIR of natural rubber/hemp fiber composites have been investigated as a function of the hemp content and absorbed dose. Physical and mechanical properties present a significant improvement as a result of adding hemp fibres in blends. Our experiments showed that the hemp fibers have a reinforcing effect on natural rubber similar to mineral fillers (chalk, carbon black, silica). The crosslinking rates of samples, measured using the Flory-Rehner equation, increase as a result of the amount of hemp in blends and the electron beam irradiation dose increasing. The swelling parameters of samples significantly depend on the amount of hemp in blends, because the latter have hydrophilic characteristics. PMID:24688419

  13. An electron microbeam cell-irradiation system at KIRAMS: performance and preliminary experiments.

    PubMed

    Kim, E H; Sun, G M; Jang, M

    2006-01-01

    An electron microbeam cell-irradiation (EMCI) system is now ready for routine operation in Korea. The system components include an electron gun operating at 1-100 keV, a beam transport chamber delivering a micron-sized beam, a cell image acquisition and positioning part and an automatic system control section. The present choice of source beam energy is 30 keV so that the radiation impact is conveyed to the targeted cells with a minimum spatial dispersion. The beam is available at 5 microm in diameter now, but can be changed in the range of 1-200 microm. The cellular dose is delivered with a standard deviation of 30% at 0.1 Gy, 10% at 1 Gy and 3% at 10 Gy. The cells are recognised by over 98% in a 1 mm x 1 mm area and the system is capable of irradiating up to 30,000 cells h(-1). PMID:17185315

  14. How does electron beam irradiation dose affect the chemical and antioxidant profiles of wild dried Amanita mushrooms?

    PubMed

    Fernandes, Ângela; Barreira, João C M; Antonio, Amilcar L; Rafalski, Andrzej; Oliveira, M Beatriz P P; Martins, Anabela; Ferreira, Isabel C F R

    2015-09-01

    As with all mushrooms, Amanita species demonstrates several conservation problems, due to a post-harvest life limited to a few days. Drying is one of the most commonly used methods in mushroom preservation. Food irradiation is another possible way to improve food quality and insure its security. Among the emerging irradiation technologies, electron beam irradiation has wide applications, allowing for high throughput, wide flexibility and potential, without any negative effect on the environment. The effects of different electron beam irradiation doses in Amanita genus, were assessed by measuring the changes produced on a wide variety of nutritional, chemical and antioxidant indicators. The evaluated profiles indicated differences between non-irradiated and irradiated samples, however a high similarity was observed among different doses. This finding advises that the highest assayed dose (10 kGy) be applied, ensuring a higher effectiveness from a decontamination and disinfestation perspective, without having any stronger effects than those observed by the lower doses.

  15. Calculation of diffraction patterns associated with electron irradiation induced amorphization of CuTi

    SciTech Connect

    Devanathan, R.; Meshii, M. . Dept. of Materials Science and Engineering); Lam, N.Q.; Okamoto, P. ); Sabochik, M.J. . Dept. of Engineering Physics)

    1990-11-01

    A new approach that uses the multislice method in conjunction with molecular dynamics simulations to study electron irradiation induced amorphisation is presented. Diffraction patterns were calculated for CuTi and found to be more sensitive than the pair correlation function to the structural changes preceding amorphisation. The results from this approach and from a study of long range order are presented. 16 refs., 8 figs.

  16. Electron Irradiation Effects on Nanocrystal Quantum Dots Used in Bio-Sensing Applications

    NASA Technical Reports Server (NTRS)

    Leon, R.; Nadeau, J.; Evans, K.; Paskova, T.; Monemar, B.

    2004-01-01

    Effects of electron irradiation on some of the optical properties in organic CdSe nanocrystals coated in trioctylphosphine oxide (TOPO) and biologically compatible CdSe nanocrystals coated in mercaptoacetic acid, as CdSe as CdSe nanocrystals conjugated with the protein are investigated using the technique of cathodoluminescence. Effects of varying the beam energy and temperatures were examined and faster degradation at cryogenic temperatures and higher beam energies was found under some conditions.

  17. Sustained transdermal release of diltiazem hydrochloride through electron beam irradiated different PVA hydrogel membranes

    NASA Astrophysics Data System (ADS)

    Bhunia, Tridib; Goswami, Luna; Chattopadhyay, Dipankar; Bandyopadhyay, Abhijit

    2011-08-01

    Extremely fast release of diltiazem hydrochloride (water soluble, anti anginal drug used to treat chest pain) together with its faster erosion has been the primary problem in conventional oral therapy. It has been addressed in this paper by encapsulating the drug in electron beam irradiated various poly (vinyl alcohol) hydrogel membranes and delivering it through transdermal route. Results show excellent control over the release of diltiazem hydrochloride through these membranes subject to their physico-mechanicals.

  18. Fluence Uniformity Measurements in an Electron Accelerator Used for Irradiation of Extended Area Solar Cells and Electronic Circuits for Space Applications

    NASA Technical Reports Server (NTRS)

    Uribe, Roberto M.; Filppi, Ed; Zhang, Shubo

    2007-01-01

    It is common to have liquid crystal displays and electronic circuit boards with area sizes of the order of 20x20 sq cm on board of satellites and space vehicles. Usually irradiating them at different fluence values assesses the radiation damage in these types of devices. As a result, there is a need for a radiation source with large spatial fluence uniformity for the study of the damage by radiation from space in those devices. Kent State University s Program on Electron Beam Technology has access to an electron accelerator used for both research and industrial applications. The electron accelerator produces electrons with energies in the interval from 1 to 5 MeV and a maximum beam power of 150 kW. At such high power levels, the electron beam is continuously scanned back and forth in one dimension in order to provide uniform irradiation and to prevent damage to the sample. This allows for the uniform irradiation of samples with an area of up to 1.32 sq m. This accelerator has been used in the past for the study of radiation damage in solar cells (1). However in order to irradiate extended area solar cells there was a need to measure the uniformity of the irradiation zone in terms of fluence. In this paper the methodology to measure the fluence uniformity on a sample handling system (linear motion system), used for the irradiation of research samples, along the irradiation zone of the above-mentioned facility is described and the results presented. We also illustrate the use of the electron accelerator for the irradiation of large area solar cells (of the order of 156 sq cm) and include in this paper the electrical characterization of these types of solar cells irradiated with 5 MeV electrons to a total fluence of 2.6 x 10(exp 15) e/sq cm.

  19. Influence of some crosslinking agents on thermal and mechanical properties of electron beam irradiated polylactide

    NASA Astrophysics Data System (ADS)

    Rytlewski, Piotr; Malinowski, RafaŁ; Moraczewski, Krzysztof; Żenkiewicz, Marian

    2010-10-01

    The aim of this article was to determine and compare the influence of trimethylopropane trimethacylate (TMPTA) and trially isocyanurate (TAIC) crosslinking agents on thermal and mechanical properties of electron beam irradiated polylactide (PLA). The blends were made of PLA mixed with 3 wt% of TMPTA (PLA/TMPTA), and PLA mixed with 3 wt% of TAIC (PLA/TAIC). Injection moulded samples were irradiated with the use of high energy (10 MeV) electron beam at various radiation doses to crosslinking PLA macromolecules. Thermal and mechanical properties were investigated by means of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile strength, and impact strength measurements. The samples were also characterized by Fourier transform infrared spectroscopy (FTIR). It was found that under the influence of electron irradiation PLA/TMPTA samples underwent degradation while PLA/TAIC samples became crosslinked. Tensile and impact strengths of PLA/TMPTA samples decreased with increasing radiation dose while an enhancement of these properties for PLA/TAIC samples was observed.

  20. Investigation of the combined effect of neutron irradiation and electron beam exposure on pure tungsten

    NASA Astrophysics Data System (ADS)

    Van Renterghem, W.; Uytdenhouwen, I.

    2016-08-01

    Pure tungsten samples were neutron irradiated in the BR2 reactor of SCK·CEN to fluences of 1.47 × 1020 n/cm2 and 4.74 × 1020 n/cm2 at 300 °C under Helium atmosphere and exposed to the electron beam of the Judith 1 installation The effect of these treatments on the defect structure was studied with transmission electron microscopy. In the irradiated samples the defect structure in the bulk is compared to the structure at the surface. The neutron irradiation created a large amount of a/2‹111› type dislocation loops forming dislocation rafts. The loop density increased from 8.5 × 1021/m³ to 9 × 1022/m³ with increasing dose, while the loop size decreased from 5.2 nm to 3.5 nm. The electron beam exposure induced significant annealing of the defects and almost all of the dislocation loops were removed. The number of line dislocations in that area increased as a result of the thermal stresses from the thermal shock.

  1. Electron-irradiation damage in chromium nitrides and chromium oxynitride thin films.

    PubMed

    Mitterbauer, Christoph; Grogger, Werner; Wilhartitz, Peter; Hofer, Ferdinand

    2006-01-01

    The aim of this work is to monitor changes of the N-K electron energy-loss near-edge structure (ELNES) of chromium nitride layers (CrN) introduced by electron irradiation in a transmission electron microscope (TEM). These changes are different for each sample material and seem to give an indication for a particular composition. The CrN samples (CrN and Cr(0.47)N(0.53)) were prepared on silicon wafers by reactive magnetron sputtering of a metallic chromium target in nitrogen plasma. In addition, a CrON sample (Cr(0.5)O(0.2)N(0.3)) was also investigated. This sample was prepared by the addition of oxygen to the plasma during film deposition. The ELNES of the N-K ionization edge of stoichiometric CrN shows a typical fine structure (peaks at 399.0 and 401.1 eV) and remains nearly unaffected even after high-current-density irradiation. On the other hand the N-K fine structures of Cr(0.47)N(0.53) and Cr(0.5)O(0.2)N(0.3) show a change of the ELNES with irradiation dose. This presumably arises from a 1s-pi*-transition of molecular nitrogen located at interstitial positions in these samples. PMID:16554164

  2. Evaluation of some selected vaccines and other biological products irradiated by gamma rays, electron beams and X-rays

    NASA Astrophysics Data System (ADS)

    May, J. C.; Rey, L.; Lee, Chi-Jen

    2002-03-01

    Molecular sizing potency results are presented for irradiated samples of one lot of Haemophilus b conjugate vaccine, pneumococcal polysaccharide type 6B and typhoid vi polysaccharide vaccine. The samples were irradiated (25 kGy) by gamma rays, electron beams and X-rays. IgG and IgM antibody response in mice test results (ELISA) are given for the Hib conjugate vaccine irradiated at 0°C or frozen in liquid nitrogen.

  3. Dislocation sweeping of defects in neutron- and electron-irradiated niobium

    SciTech Connect

    Loomis, B.A.; Otero, M.P.

    1983-10-01

    The glide of dislocations in a (441)-oriented Nb single crystal irradiated at 325 K with 5.5 x 10/sup 21/ neutrons/m/sup 2/ (E > 0.1 MeV) is shown for increasing time of tensile elongation (2 x 10/sup -4/ mm/s) in the High Voltage Electron Microscope at Argonne National Laboratory. The dimensions of the tensile specimen in the guage length were approximately 2 mm x 0.5 mm x 0.0001 mm. An electron energy of 900 keV was used during the simultaneous deformation and TEM observation.

  4. EPR study of electron traps in x-ray-irradiated yttria-stabilized zirconia

    SciTech Connect

    Azzoni, C.B.; Paleari, A. )

    1989-10-01

    Single crystals of yttria-stabilized zirconia (12 mol % of Y{sub 2}O{sub 3}) have been x-ray irradiated at room temperature. The electron paramagnetic resonance spectrum of the filled electron traps is analyzed in terms of a single oxygen vacancy type of defect with its symmetry axis along the {l angle}111{r angle} direction. The angular dependence of the linewidth and the asymmetry of the line shape are attributed to the disordered rearrangements of the anion sublattice surrounding the oxygen vacancy. This affects the local crystal fields and the directions of the symmetry axis of the defects.

  5. Thermoluminescence response of dysprosium doped strontium tetraborate glasses subjected to electron irradiations.

    PubMed

    Lim, Tou Ying; Wagiran, H; Hussin, R; Hashim, S

    2015-08-01

    The paper presents the thermoluminescence (TL) response of strontium tetraborate glass subjected to electron irradiations at various Dy2O3 concentrations ranging from 0.00 to 1.00mol%. All glass samples exhibited single broad peak with maximum peak temperature positioned at 170-215°C. The optimum TL response was found at Dy2O3 concentration 0.75mol%. This glass showed good linearity and higher sensitivity for 7MeV compared to 6MeV electrons. Analysis of kinetic parameters showed that the glasses demonstrate second order kinetic.

  6. Removing THMs from drinking water using high-energy electron-beam irradiation

    SciTech Connect

    Cooper, W.J.; Cadavid, E.M.; Nickelson, M.G.; Lin, K. ); Kurucz, C.N.; Waite, T.D. )

    1993-09-01

    High-energy electron-beam irradiation was shown to be efficient for removing trihalomethanes (THMs) from drinking water. The process was demonstrated on a 1.5-MeV variable-current (0--50 mA) electron-beam system at a flow rate of 120 gpm and on a [sup 60]Co gamma source. Of the four THMs, chloroform was the most difficult, i.e., energy-intensive, to remove. The brominated THMs were much more efficiently destroyed by the process. Organically bound halogens were converted to halide anions, and no organic halogen or oxyhalogen reaction by-products were observed.

  7. Comparison of Quality of Bologna Sausage Manufactured by Electron Beam or X-Ray Irradiated Ground Pork.

    PubMed

    Shin, Mee-Hye; Lee, Ju-Woon; Yoon, Young-Min; Kim, Jong Heon; Moon, Byeong-Geum; Kim, Jae-Hun; Song, Beom-Suk

    2014-01-01

    Ground lean pork was irradiated by an electron beam or X-rays to compare the effects of two types of radiation generated by a linear accelerator on the quality of Bologna sausage as a model meat product. Raw ground lean pork was vacuum packaged at a thickness of 1.5 cm and irradiated at doses of 2, 4, 6, 8, or 10 kGy by an electron beam (2.5 MeV) or X-rays (5 MeV). Solubility of myofibrillar proteins, bacterial counts, and thiobarbituric acid reactive substance (TBARS) values were determined for raw meat samples. Bologna sausage was manufactured using the irradiated lean pork, and total bacterial counts, TBARS values, and quality properties (color differences, cooking yield, texture, and palatability) were determined. Irradiation increased the solubility of myofibrillar proteins in a dose-dependent manner (p<0.05). Bacterial contamination of the raw meat was reduced as the absorbed dose increased, and the reduction was the same for both radiation types. Differences were observed only between irradiated and non-irradiated samples (p<0.05). X-ray irradiation may serve as an alternative to gamma irradiation and electron beam irradiation.

  8. Comparison of Quality of Bologna Sausage Manufactured by Electron Beam or X-Ray Irradiated Ground Pork

    PubMed Central

    Shin, Mee-Hye

    2014-01-01

    Ground lean pork was irradiated by an electron beam or X-rays to compare the effects of two types of radiation generated by a linear accelerator on the quality of Bologna sausage as a model meat product. Raw ground lean pork was vacuum packaged at a thickness of 1.5 cm and irradiated at doses of 2, 4, 6, 8, or 10 kGy by an electron beam (2.5 MeV) or X-rays (5 MeV). Solubility of myofibrillar proteins, bacterial counts, and thiobarbituric acid reactive substance (TBARS) values were determined for raw meat samples. Bologna sausage was manufactured using the irradiated lean pork, and total bacterial counts, TBARS values, and quality properties (color differences, cooking yield, texture, and palatability) were determined. Irradiation increased the solubility of myofibrillar proteins in a dose-dependent manner (p<0.05). Bacterial contamination of the raw meat was reduced as the absorbed dose increased, and the reduction was the same for both radiation types. Differences were observed only between irradiated and non-irradiated samples (p<0.05). X-ray irradiation may serve as an alternative to gamma irradiation and electron beam irradiation. PMID:26761284

  9. Atomic-scale dynamics of triangular hole growth in monolayer hexagonal boron nitride under electron irradiation

    NASA Astrophysics Data System (ADS)

    Ryu, Gyeong Hee; Park, Hyo Ju; Ryou, Junga; Park, Jinwoo; Lee, Jongyeong; Kim, Gwangwoo; Shin, Hyeon Suk; Bielawski, Christopher W.; Ruoff, Rodney S.; Hong, Suklyun; Lee, Zonghoon

    2015-06-01

    The production of holes by electron beam irradiation in hexagonal boron nitride (hBN), which has a lattice similar to that of graphene, is monitored over time using atomic resolution transmission electron microscopy. The holes appear to be initiated by the formation of a vacancy of boron and grow in a manner that retains an overall triangular shape. The hole growth process involves the formation of single chains of B and N atoms and is accompanied by the ejection of atoms and bundles of atoms along the hole edges, as well as atom migration. These observations are compared to density functional theory calculations and molecular dynamics simulations.The production of holes by electron beam irradiation in hexagonal boron nitride (hBN), which has a lattice similar to that of graphene, is monitored over time using atomic resolution transmission electron microscopy. The holes appear to be initiated by the formation of a vacancy of boron and grow in a manner that retains an overall triangular shape. The hole growth process involves the formation of single chains of B and N atoms and is accompanied by the ejection of atoms and bundles of atoms along the hole edges, as well as atom migration. These observations are compared to density functional theory calculations and molecular dynamics simulations. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01473e

  10. New electron beam facility for irradiated plasma facing materials testing in hot cell

    SciTech Connect

    Sakamoto, N.; Kawamura, H.; Akiba, M.

    1995-09-01

    Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop of plasma facing components which can resist these. Then, we have established electron beam heat facility ({open_quotes}OHBIS{close_quotes}, Oarai Hot-cell electron Beam Irradiating System) at a hot cell in JMTR (Japan Materials Testing Reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30kV (constant) and 1.7A, respectively. The loading time of electron beam is more than 0.1ms. The shape of vacuum vessel is cylindrical, and the mainly dimensions are 500mm in inner diameter, 1000mm in height. The ultimate vacuum of this vessel is 1 x 10{sup -4}Pa. At present, the facility for thermal shock test has been established in a hot cell. And performance estimation on the electron beam is being conducted. Presently, the devices for heat loading tests under steady state will be added to this facility.

  11. Electron beam irradiation of sun-dried apricots for quality maintenance

    NASA Astrophysics Data System (ADS)

    Wei, Ming; Zhou, Linyan; Song, Hongbo; Yi, Jianyong; Wu, Bin; Li, Yaru; Zhang, Le; Che, Fengbin; Wang, Zhidong; Gao, Meixu; Li, Shurong

    2014-04-01

    The chemical, sensory, and microbial quality parameters of electron beam (EB)-irradiated and non-irradiated sun-dried apricots were periodically evaluated to optimize the EB irradiation of sun-dried apricots for quality maintenance. The sun-dried apricots were treated with 1.0, 2.0, 3.0, 4.0, and 5.0 kGy of EB and subsequently stored at ambient temperature. EB treatment at 1.0-3.0 kGy proved to be beneficial for retaining high levels of β-carotene, ascorbic acid, titratable acidity, total sugars, and color without any significant effect on sensory properties. Doses of 1.0-3.0 kGy retained the β-carotene content of sun-dried apricots to 8.21%, 9.27%, and 10.43% compared with 6.09% in control samples after 10 months of storage. After 10 months of storage, the maximum losses of ascorbic acid were 37.8% in control samples and 35.5% in 3.0 kGy-irradiated samples. Titratable acidity and total sugars were significantly enhanced immediately after 1.0-3.0 kGy irradiation treatment, and both parameters showed no significant change after 10 months of storage. Samples subjected to EB treatment at 3.0 kGy maintained a high overall acceptability of sun-dried apricots. Decreased number of viable microorganisms to below detection limits were observed after 3.0 kGy irradiation, and compared with the control, the logarithmic reductions after 10 months of storage were 0.98 for yeast and mold count, as well as 1.71 for bacterial count.

  12. Spinal axis irradiation with electrons: Measurements of attenuation by the spinal processes

    SciTech Connect

    Muller-Runkel, R.; Vijayakumar, S.

    1986-07-01

    Electrons may be used beneficially for spinal axis irradiation in medulloblastoma children to avoid some of the long-term sequelae induced by megavoltage photons. However, the attenuation by the intervening bone ought to be considered. Three-dimensional computer treatment planning with inhomogeneity correction for electron beams is not yet generally available, and alternate methods are needed to evaluate the attenuation by the complex bony structure of the spine. Here, we present our experimental data showing the alteration in the electron isodoses due to the intervening spinous processes. Film dosimetric measurements were made in the vertebral columns obtained from autopsies of a goat, a dog, and a child. Our results show that electron beam therapy for the spinal axis is a viable option.

  13. Electronic and Optical Properties of Energetic Particle-IrradiatedIn-rich InGaN

    SciTech Connect

    Li, S.X.; Yu, K.M.; Jones, R.E.; Wu, J.; Walukiewicz, W.; AgerIII, J.W.; Shan, W.; Haller, E.E.; Lu, Hai; Schaff, William J.; Kemp, W.

    2005-04-13

    We have carried out a systematic study of the effects of irradiation on the electronic and optical properties of InGaN alloys over the entire composition range. High energy electrons, protons, and {sup 4}He{sup +} were used to produce displacement damage doses (D{sub d}) spanning over five orders of magnitude. The free electron concentrations in InN and In-rich InGaN increase with D{sub d} and finally saturate after a sufficiently high D{sub d}. The saturation of carrier density is attributed to the formation of native donors and the Fermi level pinning at the Fermi Stabilization Energy (E{sub FS}), as predicted by the amphoteric native defect model. Electrochemical capacitance-voltage (ECV) measurements reveal a surface electron accumulation whose concentration is determined by pinning at E{sub FS}.

  14. Real-Time Time-Dependent DFT Study of Electronic Stopping in Semiconductors under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Yost, Dillon C.; Reeves, Kyle G.; Kanai, Yosuke

    Understanding the detailed mechanisms of how highly energetic charged particles transfer their kinetic energy to electronic excitations in materials has become an important topic in various technologies ranging from nuclear energy applications to integrated circuits for space missions. In this work, we use our new large-scale real-time time-dependent density functional theory simulation to investigate details of the ion-velocity-dependent dynamics of electronic excitations in the electronic stopping process. In particular, we will discuss how point defects in semiconductor materials influence the electronic stopping process under proton irradiation, using silicon carbide (3C-SiC) as a representative material due to its great technological importance. Additionally, we will provide atomistic insights into existing analytical models that are based on the plane-wave Born approximation by examining velocity-dependence of the projectile charge from first-principles simulations.

  15. Volatile compounds and odor traits of dry-cured ham (Prosciutto crudo) irradiated by electron beam and gamma ray

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prosciutto crudo were irradiated at 0, 3 and 6kGy by gamma ray (GR) and electron beam (EB), respectively. The odor scores and volatile compounds were examined after 7 days storage at 4'. Volatile compounds from samples without and with irradiation at 6kGy were analyzed by GC-MS. Fifty-nine compounds...

  16. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Technical Reports Server (NTRS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1995-01-01

    When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

  17. X-ray irradiation induced changes in electron transport in stabilized a-Se photoconductors

    SciTech Connect

    Walornyj, M.; Kasap, S. O.

    2013-12-07

    We have examined the effect of high-dose x-ray irradiation on electron transport in stabilized amorphous selenium (a-Se) x-ray photoconductive films (of the type used in x-ray image detectors) by measuring the electron lifetime τ{sub e} through interrupted-field time-of-flight experiments. X-ray induced effects have been examined through two types of experiments. In recovery experiments, the a-Se was preirradiated with and without an applied field (5 V/μm) during irradiation with sufficient dose (typically ∼20 Gy at 21 °C) to significantly reduce the electron lifetime by ∼50%, and then the recovery of the lifetime was monitored as a function of time at three different temperatures, 10 °C, 21 °C, and 35 °C. The lifetime recovery kinetics was exponential with a relaxation time τ{sub r} that is thermally activated with an activation energy of 1.66 eV. τ{sub r} is a few hours at 21 °C and only a few minutes at 35 °C. In experiments examining the irradiation induced effects, the a-Se film was repeatedly exposed to x-ray radiation and the changes in the drift mobility and lifetime were monitored as a function of accumulated dose D. There was no observable change in the drift mobility. At 21 °C, the concentration of x-ray induced deep traps (or capture centers), N{sub d}, increases linearly with D (N{sub d} ∼ D) whereas at 35 °C, the recovery process prevents a linear increase in N{sub d} with D, and N{sub d} saturates. In all cases, even under high dose irradiation (∼50 Gy), the lifetime was recoverable to its original equilibrium (pre-exposure) value within a few relaxation times.

  18. Comparison of irradiated stFZ silicon sensors using LHC speed front-end electronics

    NASA Astrophysics Data System (ADS)

    Eckert, S.; Ehrich, T.; Jakobs, K.; Kühn, S.; Parzefall, U.

    2007-12-01

    Results from irradiated detector modules assembled with sensors made out of standard p-in-n FZ silicon will be presented. The modules were read out using LHC speed front-end electronics and characterised with different techniques. Two complementary methods to generate the charge inside the sensor were used: An IR laser set-up with a wavelength of λ=982 nm and a β set-up utilising a 90Sr source allowing for both relative and absolute CCE measurements. As the aim of our measurement programme is to develop silicon detectors able to operate at the sLHC, these modules were irradiated with three different fluences with the highest corresponding roughly to the fluence expectations for an LHC luminosity upgrade at a radial distance of r≈35 cm [M. Huhtinen, First CMS Upgrade Workshop, CERN, February 26-27, 2004. ]. The sensors were characterised before and after irradiation with 26 MeV protons. After irradiation the modules were stored at temperatures below -40C and operated at temperatures around -5C to limit the leakage current and annealing effects. The full depletion voltage Vfd and the charge collection efficiency have been measured.

  19. DNA double strand breaks in rat epidermis following irradiation with electrons

    SciTech Connect

    Shulman, K.

    1986-05-01

    Although radiation induced single strand breaks in rat epidermis are repaired fairly quickly (t-1/2 = 21 minutes), the fate of DNA double strand breaks in the same cells is unclear. Here we have attempted to measure dsb's in rat epidermis by neutral elution. The DNA of 28 day old CD rats was prelabeled with 6 I.P. injections at 2.0 uCi/g body weight of /sup 3/H-TdR. The dorsal skin was irradiated with a 0.8 MeV electron beam. The epidermis was removed by trypsinization at 4/sup 0/C and a single cell suspension was made. The cells were layered onto a polycarbonate filter, lysed, and eluted at pH 9.6. Doses of at least 6000 rads were needed to detect dsb's in vivo. Dsb's were still detectable in the epidermis 3 hours after irradiation. The amount of dsb's had returned to non-irradiated levels 8 hours after irradiation. 77 refs., 2 figs., 1 tab.

  20. Detection of gamma irradiated fig seeds by analysing electron spin resonance.

    PubMed

    Engin, Birol; Aydaş, Canan; Polat, Mustafa

    2011-06-15

    Seeds of fig produced in Turkey were studied by electron spin resonance (ESR) technique for detection purposes. Unirradiated fig seeds (control) exhibited a weak ESR singlet at g=2.0052±0.0003 (native signal). Irradiation induced at least one additional intense singlet overlapping to the control signal and caused a significant increase in signal intensity without any changes in spectral patterns. Variation of ESR signal intensity of irradiated samples at room temperature with time in a long-term showed that free radicals responsible from the ESR spectrum of fig seeds were not stable but detectable after 80days. Annealing studies at five different temperatures were used to determine the kinetic behaviour and activation energy of the radiation-induced radicals in fig seeds. A study on microwave saturation characteristics and thermal behaviour of the ESR singlet (g=2.0052) in irradiated and unirradiated fig seed samples was also carried out by using ESR technique. These preliminary results indicate that microwave saturation characteristics of the ESR signal at room and low temperatures may be useful method to distinguish irradiated fig seeds from unirradiated ones.

  1. Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Bin; Park, Dong-Won; Jeun, Joon-Pyo; Oh, Seung-Hwan; Nho, Young-Chang; Kang, Phil-Hyun

    2012-08-01

    iO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20-100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films.

  2. Comparative study on the effect of electron beam irradiation on the physical properties of ethylene-vinyl acetate copolymer composites

    NASA Astrophysics Data System (ADS)

    Wang, Bibo; Hong, Ningning; Shi, Yongqian; Wang, Biao; Sheng, Haibo; Song, Lei; Tang, Qinbo; Hu, Yuan

    2014-04-01

    Ethylene-vinyl acetate copolymer (EVA) flame retarded by a combination of cellulose acetate butyrate (CAB) microencapsulated ammonium polyphosphate (MCAPP) and polyamide-6 (PA-6) have been crosslinked by high energy electron beam irradiation. The effect of high energy electron beam irradiation on the crosslinking degree, mechanical, electrical and thermal properties of EVA/MCAPP/PA-6 cable material was studied by gel content, heat extention test, mechanical test, dynamic mechanical analysis, high-insulation resistance meter and thermogravimetric analysis. The gel content and heat extention test results showed that the EVA/MCAPP/PA-6 composites can be easily crosslinked by electron beam irradiation. The tensile strength of EVA composites was drastically increased from 16.2 to maximum 26.2 MPa as the electron beam irradiation dose increases from 0 to 160 kGy. The volatilized products of EVA/MCAPP/PA-6 composites were analyzed and compared by thermogravimetric analysis/infrared spectrometry (TG-FTIR).

  3. Stability of carbonaceous dust analogues and glycine under UV irradiation and electron bombardment.

    PubMed

    Maté, Belén; Tanarro, Isabel; Moreno, Miguel A; Jiménez-Redondo, Miguel; Escribano, Rafael; Herrero, Víctor J

    2014-01-01

    The effect of UV photon (120-200 nm) and electron (2 keV) irradiation of analogues of interstellar carbonaceous dust and of glycine were investigated by means of IR spectroscopy. Films of hydrogenated amorphous carbon (HAC), taken as dust analogues, were found to be stable under UV photon and electron bombardment. High fluences of photons and electrons, of the order of 10(19) cm(-2), were needed for a film depletion of a few percent. UV photons were energetically more effective than electrons for depletion and led to a certain dehydrogenation of the HAC samples, whereas electrons led seemingly to a gradual erosion with no appreciable changes in the hydrocarbon structure. The rates of change observed may be relevant over the lifetime of a diffuse cloud, but cannot account for the rapid changes in hydrocarbon IR bands during the evolution of some proto-planetary nebulae. Glycine samples under the same photon and electron fluxes decay at a much faster rate, but tend usually to an equilibrium value different from zero, especially at low temperatures. Reversible reactions re-forming glycine, or the build-up of less transparent products, could explain this behavior. CO2 and methylamine were identified as UV photoproducts. Electron irradiation led to a gradual disappearance of the glycine layers, also with formation of CO2. No other reaction products were clearly identified. The thicker glycine layers (a few hundred nm) were not wholly depleted, but a film of the order of the electron penetration depth (80 nm), was totally destroyed with an electron fluence of -1 x 10(18) cm(-2). A 60 nm ice layer on top of glycine provided only partial shielding from the 2 keV electrons. From an energetic point of view, 2 keV electrons are less efficient than UV photons and, according to literature data, much less efficient than MeV protons for the destruction of glycine. The use of keV electrons to simulate effects of cosmic rays on analogues of interstellar grains should be taken with

  4. Effect of electron irradiation in vacuum on FEP-A silicon solar cell covers. [Fluorinated Ethylene-Propylene-A

    NASA Technical Reports Server (NTRS)

    Marsik, S. J.; Broder, J. D.

    1975-01-01

    The effect of irradiation on the light transmittance of ethylene-propylene-A (FEP-A) was investigated by measuring the short-circuit current of the cells after each of several electron dose increments, immediately after total irradiation, and 16 hours after total irradiation. Results indicated no apparent overall loss in transmission due to irradiation of FEP-A. However, filter wheel measurements revealed a 'darkening' of the FEP-A at the blue end of the spectrum. Some embrittlement of the FEP-A occurred at an accumulated dose of 67,500,000 rads.

  5. GaAs detectors irradiated by electrons at different dose rates

    NASA Astrophysics Data System (ADS)

    Sagatova, A.; Zatko, B.; Sedlackova, K.; Pavlovic, M.; Fulop, M.; Bohacek, P.; Necas, V.

    2014-12-01

    The radiation hardness of Semi-Insulating (SI) GaAs detectors against high-energy electrons was investigated. The detectors were irradiated by 5 MeV electrons. The influence of two irradiation parameters, the total absorbed dose (up to 24 kGy) and the applied dose rate (20, 40 and 80 kGy/h), on their spectrometric properties was studied. An 241Am gamma-ray source was used to evaluate the spectrometric properties. The applied dose has negatively affected the detector CCE (Charge Collection Efficiency) and has influenced also the energy resolution. Nevertheless, a global increase of detection efficiency with the dose was observed. Three different dose rates used during irradiation did not affect the CCE, but in the range of doses from 4 to 16 kGy an influence of the applied dose rate upon two other parameters was observed. With higher dose rates, a steeper increase in the detection efficiency and significant worsening of energy resolution were achieved.

  6. Electron beam irradiation conditions and foam seat properties in polypropylene-polyethylene blends

    NASA Astrophysics Data System (ADS)

    Tokuda, S.; Kemmotsu, T.

    1995-02-01

    High expansion polypropylene foam (20-100kg/m 3) is industrially produced by blending polypropylene with thermal decomposition foaming agent, which is then irradiated with electron beam to induce crosslinking, and is finally heated, causing the foaming agent to decompose and generate foams. Here, crosslinking stage also serves to increase the melt viscosity of the mixture so that an appropriate value is obtained for foaming. In order to obtain desirable final product, the important factors in the above process are the material properties of the polypropylene and the appropriate control of crosslinking, which is governed by the selection of crosslinking-promoter and the irradiation conditions. We have used polypropylene random copolymer (R-PP) with low ethylene content and performed studies on the relation between the amount of electron beam irradiation and the degree of crosslinking and also on the effect of the multifunctional monomers as crosslinking-promoter. We have also produced foams using blends of this R-PP and linear low density polyethylene (L-LDPE) and evaluated their mechanical properties and their heat resistance.

  7. Optical and paramagnetic properties of synthetic diamond crystals irradiated with electrons and annealed

    SciTech Connect

    Poklonski, N. A. Gusakov, G. A.; Bayev, V. G. Lapchuk, N. M.

    2009-05-15

    The optical and paramagnetic properties of single crystals of synthetic diamond grown by the temperature-gradient method in high-pressure apparatuses with the systems of catalytic solvents (Co, Fe) and (Ni, Fe) are studied at room temperature. The optical absorption spectra (in the wavelength range {lambda} = 400-800 nm) and the spectra of electron spin resonance are registered for the initial diamond crystals, the crystals irradiated with 6 MeV electrons (the fluence 1.5 x 10{sup 18} cm{sup -2}), and the irradiated diamonds subjected to isochronous thermal annealing in vacuum (for 60 min). It is shown that, with such treatment, the diamond crystals synthesized with different metal catalysts (Co or Ni) exhibit similar optical properties, but different paramagnetic properties. The data obtained by infrared spectroscopy and electron spin resonance spectroscopy are coincident for radiation defects and different for nitrogen centers (the P1 centers and exchange-coupled pairs of nitrogen atoms). The spectra of the electron spin resonance of the samples annealed at temperatures below 1273 K (in the case of the Co-containing catalyst) and 1073 K (in the case of Ni-containing catalyst) exhibited broad lines produced by residual impurities of the catalyst metal and were accompanied by a distortion of the spectrum of paramagnetic nitrogen in the form of a tilt of the ESR spectra with respect to the zero line.

  8. An amorphous phase formation at palladium / silicon oxide (Pd/SiO{sub x}) interface through electron irradiation - electronic excitation process

    SciTech Connect

    Nagase, Takeshi; Yamashita, Ryo; Yabuuchi, Atsushi; Lee, Jung-Goo

    2015-11-15

    A Pd-Si amorphous phase was formed at a palladium/silicon oxide (Pd/SiO{sub x}) interface at room temperature by electron irradiation at acceleration voltages ranging between 25 kV and 200 kV. Solid-state amorphization was stimulated without the electron knock-on effects. The total dose required for the solid-state amorphization decreases with decreasing acceleration voltage. This is the first report on electron irradiation induced metallic amorphous formation caused by the electronic excitation at metal/silicon oxide interface.

  9. Fabrication of Pt nanoparticle incorporated polymer nanowires by high energy ion and electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Tsukuda, Satoshi; Takahasi, Ryouta; Seki, Shu; Sugimoto, Masaki; Idesaki, Akira; Yoshikawa, Masahito; Tanaka, Shun-Ichiro

    2016-01-01

    Polyvinylpyrrolidone (PVP)-Pt nanoparticles (NPs) hybrid nanowires were fabricated by high energy ion beam irradiation to PVP thin films including H2PtCl6. Single ion hitting caused crosslinking reactions of PVP and reduction of Pt ions within local cylindrical area along an ion trajectory (ion track); therefore, the PVP nanowires including Pt NPs were formed and isolated on Si substrate after wet-development procedure. The number of Pt NPs was easily controlled by the mixed ratio of PVP and H2PtCl6. However, increasing the amount of H2PtCl6 led to decreasing the radial size and separation of the hybrid nanowires during the wet-development. Additional electron beam irradiation after ion beam improved separation of the nanowires and controlled radial sizes due to an increase in the density of crosslinking points inner the nanowires.

  10. Void formation and microstructural development in oxide dispersion strengthened ferritic steels during electron-irradiation

    NASA Astrophysics Data System (ADS)

    Saito, J.; Suda, T.; Yamashita, S.; Ohnuki, S.; Takahashi, H.; Akasaka, N.; Nishida, M.; Ukai, S.

    1998-10-01

    ODS ferritic steels (13Cr-0.5Ti-0.2Y 2O 3) were prepared by the mechanical alloying method followed by the hot extrusion and several heat treatments including recrystallization. ODS steels with different heat treatment and a ferritic/martensitic (F/M) steel for the reference were irradiated to 12 dpa at 670-770 K in HVEM. After recrystallization, the dislocation density decreased with increasing grain size, however, the oxide particles did not show any obvious change in the size and the number density. During the electron-irradiation the microstructure was relatively stable, i.e. oxide particles showed good stability and the dislocation density remained almost constant. A limited void formation was observed in the specimens, and the suppressive effect due to dislocations with high number density was confirmed. From these results, the behavior of microstructure and the limited void formation in ODS steels have been discussed.

  11. Inhomogeneous width of oxygen-deficient centers induced by electron irradiation of silica

    SciTech Connect

    D'Amico, Michele; Leone, Maurizio; Messina, Fabrizio; Cannas, Marco; Boscaino, Roberto

    2009-02-01

    We report a study of the luminescence activity of oxygen-deficient centers stabilized in as-grown synthetic silica, as compared with the same defects induced by {beta} irradiation at increasing doses, ranging from 1.2x10{sup 3} to 5x10{sup 6} kGy. We experimentally observe a progressive broadening of the luminescence band with increasing total electron dose released on samples. By analyzing our data within a theoretical model capable of separating homogeneous and inhomogeneous contribution to the total luminescence linewidth, we observe that the increasing of the width is entirely ascribable to the inhomogeneous component which increases, in the most irradiated sample, of 60% with respect to the value in the as-grown sample. This effect can be due either to the progressive creation of new defects statistically exploring different sites of the matrix, or to a progressive structural transformation of silica host which affects the optical properties of induced point defects.

  12. Growth of the 889 per cm infrared band in annealed electron-irradiated silicon

    NASA Technical Reports Server (NTRS)

    Svensson, B. G.; Lindstrom, J. L.; Corbett, J. W.

    1985-01-01

    Isothermal annealing of electron-irradiated Czochralski silicon has been studied at four different temperatures ranging from 304 to 350 C using infrared spectroscopy. At annealing temperatures above 300 C the irradiation-induced band at 830 per cm, usually attributed to a vacancy-oxygen complex (the A center), disappears and a new band at 889 per cm grows up. Within the experimental accuracy, the activation energy for the growth of this band is found to be identical with the value given by Stavola et al. for 'anomalous' oxygen diffusion in silicon. Also the frequency factors for the two processes are in reasonable agreement. The results show that a vacancy-assisted process may provide an explanation for enhanced motion of oxygen in silicon.

  13. Unraveling irradiation induced grain growth with in situ transmission electron microscopy and coordinated modeling

    SciTech Connect

    Bufford, D. C.; Abdeljawad, F. F.; Foiles, S. M.; Hattar, K.

    2015-11-09

    Nanostructuring has been proposed as a method to enhance radiation tolerance, but many metallic systems are rejected due to significant concerns regarding long term grain boundary and interface stability. This work utilized recent advancements in transmission electron microscopy (TEM) to quantitatively characterize the grain size, texture, and individual grain boundary character in a nanocrystalline gold model system before and after in situ TEM ion irradiation with 10 MeV Si. The initial experimental measurements were fed into a mesoscale phase field model, which incorporates the role of irradiation-induced thermal events on boundary properties, to directly compare the observed and simulated grain growth with varied parameters. The observed microstructure evolution deviated subtly from previously reported normal grain growth in which some boundaries remained essentially static. In broader terms, the combined experimental and modeling techniques presented herein provide future avenues to enhance quantification and prediction of the thermal, mechanical, or radiation stability of grain boundaries in nanostructured crystalline systems.

  14. Uneven surface absorbed dose distribution in electron-accelerator irradiation of rubber items

    SciTech Connect

    Gorbunov, I.F.; Pashinin, V.I.; Vanyushkin, B.M.

    1988-02-01

    Electron accelerators for industrial use are equipped with scanning devices, where the scan frequency or linear velocity along the window may vary. In a flow technology, where the items are transported to the irradiation zone at a set rate, the speed of an item may be comparable with the scan speed, so there is substantial nonuniformity in the absorbed dose, which adversely affects the quality. We have examined the dose nonuniformity for long rubber items during vulcanization by means of LUE-8-5RV and ELV-2 accelerators. The absorbed dose is calculated for an elementary part along which the irradiation is uniform on the assumption that current density distribution in the unswept beam is uniform as a result of scattering in the foil.

  15. Dose effects in electron beam irradiation of DNA-complex thin films

    SciTech Connect

    Li, W.; Jones, R.; Spaeth, H.; Steckl, A. J.

    2010-08-09

    Electron beam irradiation of double-stranded DNA (dsDNA)-surfactant thin films was investigated. Irradiation caused dissociation, leading to increasing thin film solubility in water and degradation of dsDNA. These two effects produced a maximum concentration of dsDNA in aqueous solution at 400 {mu}C/cm{sup 2} dose. These properties resulted in dual-mode resist characteristics of the DNA-surfactant films. At low dose, the DNA films functioned as positive resist while at high dose they worked as negative resist. The transition between the two regimes also occurred at 400 {mu}C/cm{sup 2}. This implies that the cross-linking process (typical for negative resists) first requires the dissociation of the DNA-surfactant complex.

  16. Temperature, stress, and annealing effects on the luminescence from electron-irradiated silicon

    NASA Technical Reports Server (NTRS)

    Jones, C. E.; Johnson, E. S.; Compton, W. D.; Noonan, J. R.; Streetman, B. G.

    1973-01-01

    Low-temperature photoluminescence spectra are presented for Si crystals which have been irradiated with high-energy electrons. Studies of isochronal annealing, stress effects, and the temperature dependences of the luminescence are used to discuss the nature of the luminescent transitions and the properties of defects. Two dominant bands present after room-temperature anneal of irradiated material are discussed, and correlations of the properties of these bands are made with known Si defects. A band between 0.8 and 1.0 eV has properties which are related to those of the divacancy, and a band between 0.6 and 0.8 eV has properties related to those of the Si-G15(K) center. Additional peaks appear in the luminescence after high-temperature anneal; the influence of impurities and the effects of annealing of these lines are discussed.

  17. Initial increase, ''peaking effect'', in the internal friction of copper following pulsed neutron and electron irradiation

    SciTech Connect

    Simpson, H.M.; Parkin, D.M.; Goldstone, J.A.; Hemsky, J.W.

    1985-01-01

    Under certain experimental conditions the internal friction in metals can first increase and following prolonged irradiation decrease. Many models have been proposed to account for this ''peaking effect''; however, in many of the cases, no effort is made to distinguish between the influence of interstitials and/or vacancies. To determine the nature of the point defect responsible for the peaking effect in high purity copper, we have performed a series of pulsed irradiations using neutrons and electrons. In all of the experiments an initial very rapid rise in the internal friction and Young's modulus was observed. These data show that a fast diffusing defect is responsible for the peaking effect: i.e. the interstitial.

  18. New design of the pulsed electro-acoustic upper electrode for space charge measurements during electronic irradiation

    NASA Astrophysics Data System (ADS)

    Riffaud, J.; Griseri, V.; Berquez, L.

    2016-07-01

    The behaviour of space charges injected in irradiated dielectrics has been studied for many years for space industry applications. In our case, the pulsed electro-acoustic method is chosen in order to determine the spatial distribution of injected electrons. The feasibility of a ring-shaped electrode which will allow the measurements during irradiation is presented. In this paper, a computer simulation is made in order to determine the parameters to design the electrode and find its position above the sample. The obtained experimental results on polyethylene naphthalate samples realized during electronic irradiation and through relaxation under vacuum will be presented and discussed.

  19. New design of the pulsed electro-acoustic upper electrode for space charge measurements during electronic irradiation.

    PubMed

    Riffaud, J; Griseri, V; Berquez, L

    2016-07-01

    The behaviour of space charges injected in irradiated dielectrics has been studied for many years for space industry applications. In our case, the pulsed electro-acoustic method is chosen in order to determine the spatial distribution of injected electrons. The feasibility of a ring-shaped electrode which will allow the measurements during irradiation is presented. In this paper, a computer simulation is made in order to determine the parameters to design the electrode and find its position above the sample. The obtained experimental results on polyethylene naphthalate samples realized during electronic irradiation and through relaxation under vacuum will be presented and discussed.

  20. Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium in powdered weaning food by electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Hong, Yun-Hee; Park, Ji-Yong; Park, Jong-Hyun; Chung, Myong-Soo; Kwon, Ki-Sung; Chung, Kyungsook; Won, Misun; Song, Kyung-Bin

    2008-09-01

    Inactivation of Enterobacter sakazakii, Bacillus cereus, and Salmonella typhimurium were evaluated in powdered weaning food using electron-beam irradiation. E. sakazakii, B. cereus, and S. typhimurium were eliminated by irradiation at 16, 8, and 8 kGy, respectively. The D10-vlaues of E. sakazakii, B. cereus, and S. typhimurium inoculated on powdered weaning food were 4.83, 1.22, and 0.98 kGy, respectively. The results suggest that electron-beam irradiation should inhibit the growth of pathogenic bacteria on baby food without impairing qualities.

  1. Electron Irradiation and Thermal Processing of Mixed-ices of Potential Relevance to Jupiter Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Mahjoub, Ahmed; Poston, Michael J.; Hand, Kevin P.; Brown, Michael E.; Hodyss, Robert; Blacksberg, Jordana; Eiler, John M.; Carlson, Robert W.; Ehlmann, Bethany L.; Choukroun, Mathieu

    2016-04-01

    In this work we explore the chemistry that occurs during the irradiation of ice mixtures on planetary surfaces, with the goal of linking the presence of specific chemical compounds to their formation locations in the solar system and subsequent processing by later migration inward. We focus on the outer solar system and the chemical differences for ice mixtures inside and outside the stability line for H2S. We perform a set of experiments to explore the hypothesis advanced by Wong & Brown that links the color bimodality in Jupiter's Trojans to the presence of H2S in the surface of their precursors. Non-thermal (10 keV electron irradiation) and thermally driven chemistry of CH3OH-NH3-H2O (“without H2S”) and H2S-CH3OH-NH3-H2O (“with H2S”) ices were examined. Mid-IR analyses of ice and mass spectrometry monitoring of the volatiles released during heating show a rich chemistry in both of the ice mixtures. The “with H2S” mixture experiment shows a rapid consumption of H2S molecules and production of OCS molecules after a few hours of irradiation. The heating of the irradiated “with H2S” mixture to temperatures above 120 K leads to the appearance of new infrared bands that we provisionally assign to SO2and CS. We show that radiolysis products are stable under the temperature and irradiation conditions of Jupiter Trojan asteroids. This makes them suitable target molecules for potential future missions as well as telescope observations with a high signal-to-noise ratio. We also suggest the consideration of sulfur chemistry in the theoretical modeling aimed at understanding the chemical composition of Trojans and KOBs.

  2. Efficacy of Traditional Almond Decontamination Treatments and Electron Beam Irradiation against Heat-Resistant Salmonella Strains.

    PubMed

    Cuervo, Mary P; Lucia, Lisa M; Castillo, Alejandro

    2016-03-01

    Two outbreaks of salmonellosis were linked to the consumption of raw almonds from California in 2001 and 2004. As a result, federal regulations were developed, which mandate that all almonds grown in California must be treated with a process that results in a 4-log reduction of Salmonella. Because most of the technologies approved to treat almonds rely on the application of heat to control Salmonella, an evaluation of alternative technologies for inactivating heat-resistant Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W was needed. In this study, almonds were inoculated with Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W and then treated with an electron beam (e-beam) or by blanching or oil roasting. The irradiation D10-values for Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W treated with e-beam were 0.90 and 0.72 kGy, respectively. For heat treatments, thermal D10-values for Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W strains were 15.6 and 12.4 s, respectively, when subjected to blanching at 88°C and 13.2 and 10.9 s, respectively, when roasted in oil at 127 ± 2°C. No significant differences in irradiation and thermal treatment results were observed between Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W (P > 0.05), indicating that e-beam irradiation may be a feasible technology for reducing Salmonella in almonds. However, the sensory changes resulting from irradiating at the doses used in this study must be evaluated before e-beam irradiation can be used as a nonthermal alternative for decontamination of almonds. PMID:26939646

  3. Nutritional Value of electron beam irradiated cottonseed meal in broiler chickens.

    PubMed

    Nayefi, M; Salari, S; Sari, M; Behgar, M

    2016-08-01

    This study was conducted to evaluate the effect of electron beam-irradiated cottonseed meal on performance, carcass characteristics and some blood parameters of broiler chicks. Treatments were cottonseed meal (CSM) at levels of 12% and 24% (raw and irradiated at 30 kGy) and corn-soya bean meal diet (as control, without CSM and without irradiation) that used with five dietary treatments, four replicates and 10 birds of each for 42 days in completely randomized design. Feed intake (FI) and body weight gain (BWG) were recorded weekly. At 42 days of age, two birds per pen were randomly selected for the determination of carcass characteristics and blood parameters. BWG decreased with increasing levels of dietary CSM during the experiment (p < 0.05). In addition, radiation had significant positive effect in broilers fed 12% compared with those fed 24% CSM. FI in chicks fed control and diet containing 24% CSM were increased significantly in starter period. But FI was significantly decreased in broilers consumed CSM compare to the control in grower and during the experiment. Feed conversion ratio (FCR) increased with increasing levels of CSM in the diets. Relative weights of liver, gastrointestinal tract (GI), pancreas, gizzard and abdominal fat were increased by increasing levels of CSM in the diet (p < 0.05). Glucose, cholesterol, HDL, triglyceride and phosphorous concentrations increased, and LDL concentration decreased as the dietary CSM levels increased (p < 0.05). But radiation had not significant effect on blood parameters. Electron irradiation seems to be a good procedure to improve the nutritional quality of CSM, but it seems higher dose of it was needed to improve performance of chickens. PMID:26621476

  4. Peculiarities of the charge transport in the gas discharge electronic device with irradiated porous zeolite

    NASA Astrophysics Data System (ADS)

    Ozturk, Sevgul; Koseoglu, Kivilcim; Ozer, Metin; Salamov, Bahtiyar G.

    2015-11-01

    The influence of pressure and β-radiation (1 kGy β doses) on the charge transport mechanism, charge trapping effects in porous zeolite surfaces and breakdown voltage (UB) are discussed in atmospheric microplasmas for the first time. This is due to exposure the zeolite cathode (ZC) to β-radiation resulting in substantial decreases in the UB, discharge currents and conductivity due to increase in porosity of the material. Results indicated that the enhancement of plasma light intensity and electron emission from the ZC surface with the release of trapped electrons which are captured by the defect centers following β-irradiation. The porosity of the ZC and radiation defect centers has significant influence on the charge transport of the microstructure and optical properties of the devices manufactured on its base. Thus, we confirm that the ZCir is a suitable cathode material for plasma light source, field emission displays, energy storage devices and low power gas discharge electronic devices.

  5. Microtrench/oxide island reduction with electron beam irradiation in high aspect ratio oxide etching

    NASA Astrophysics Data System (ADS)

    Watanabe, M.; Shaw, D. M.; Collins, G. J.

    2001-10-01

    During high aspect ratio oxide etching, the feature surface charges up and deflects the subsequent ion trajectories to the sidewalls due to local electric field, which results in microtrenching at the feature edges. At the etch end point, the microtrench reaches the conducting underlayer, which does not accumulate charge, and an oxide island remains at the center if no overetching is used. An electron beam source [1] is developed to neutralize the positive charge buildup at the feature bottom during etching. SEM images of the etch profiles show that the microtrench/oxide island formation is reduced with the electron beam irradiation. The electric field and ion trajectories within an etch feature are calculated, indicating that the reduction of the microtrench/oxide island formation is achieved by electron beam charge neutralization te at the feature bottom. [1] D. M. Shaw, M. Watanabe, G. J. Collins, and H. Sugai, Jpn. J. Appl. Phys. 38, 87 (1999).

  6. Directed fast electron beams in ultraintense picosecond laser irradiated solid targets

    SciTech Connect

    Ge, X. L.; Lin, X. X.; Yuan, X. H. E-mail: ytli@iphy.ac.cn; Sheng, Z. M.; Carroll, D. C.; Neely, D.; Gray, R. J.; Tresca, O.; McKenna, P.; Yu, T. P.; Chen, M.; Liu, F.; Zhuo, H. B.; Zielbauer, B.; and others

    2015-08-31

    We report on fast electron transport and emission patterns from solid targets irradiated by s-polarized, relativistically intense, picosecond laser pulses. A beam of multi-MeV electrons is found to be transported along the target surface in the laser polarization direction. The spatial-intensity and energy distributions of this beam are compared with the beam produced along the laser propagation axis. It is shown that even for peak laser intensities an order of magnitude higher than the relativistic threshold, laser polarization still plays an important role in electron energy transport. Results from 3D particle-in-cell simulations confirm the findings. The characterization of directional beam emission is important for applications requiring efficient energy transfer, including secondary photon and ion source development.

  7. Recovery of shallow junction GaAs solar cells damaged by electron irradiation

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Conway, E. J.

    1978-01-01

    Solar cells operated in space are subject to degradation from electron and proton radiation damage. It has been found that for deep junction p-GaAlAs/p-GaAs solar cells some of the electron radiation damage is removed by annealing the cells at 200 C. The reported investigation shows that shallow junction p-GaAlAs/p-GaAs/n-GaAs heteroface solar cells irradiated with 1 MeV electrons show a more complete recovery of short-circuit current than do the deep junction cells. The heteroface p-GaAlAs/p-GaAs/n-GaAs solar cells studied were fabricated using the etch-back epitaxy process.

  8. Electron spin resonance shift and linewidth broadening of nitrogen-vacancy centers in diamond as a function of electron irradiation dose

    SciTech Connect

    Kim, Edwin; Acosta, Victor M.; Bauch, Erik; Budker, Dmitry; Hemmer, Philip R.

    2012-08-20

    A high-nitrogen-concentration diamond sample was subjected to 200-keV electron irradiation using a transmission electron microscope. The optical and spin-resonance properties of the nitrogen-vacancy (NV) color centers were investigated as a function of the irradiation dose up to 6.4 Multiplication-Sign 10{sup 21} e{sup -}/cm{sup 2}. The microwave transition frequency of the NV{sup -} center was found to shift by up to 0.6% (17.1 MHz) and the linewidth broadened with increasing electron-irradiation dose. Unexpectedly, the measured magnetic sensitivity is best at the lowest irradiation dose, even though the NV concentration increases monotonically with increasing dose. This is in large part due to a sharp reduction in optically detected spin contrast at higher doses.

  9. Interface formation between calcium and electron-irradiated poly(3-hexylthiophene).

    PubMed

    Bebensee, Fabian; Zhu, Junfa; Baricuatro, Jack H; Farmer, Jason A; Bai, Yun; Steinrück, Hans-Peter; Campbell, Charles T; Gottfried, J Michael

    2010-06-15

    The adsorption of Ca on electron-irradiated poly(3-hexylthiophene) (P3HT) surfaces at 300 K (E(kin) = 100 eV) has been studied by adsorption microcalorimetry, atomic beam/surface scattering, X-ray photoelectron spectroscopy (XPS), and low-energy He(+) ion scattering spectroscopy (LEIS). The results are compared to previous studies of Ca adsorption on pristine P3HT. The major structural effect of electron irradiation is a substantial increase in the fraction of unsaturated carbon atoms, probably a result of electron-induced hydrogen abstraction from the hexyl chains and formation of new C=C double bonds. No loss of sulfur was observed. The combined XPS, LEIS, and calorimetry data indicate that the reaction and growth behavior of Ca on P3HT surfaces is not significantly affected by this electron damage, apart from an increased sticking probability at low coverages. The sticking probability of Ca on the irradiated P3HT is initially 0.63, compared to 0.36 on the pristine surface. It increases with coverage, approaching unity between 4 and 5 ML. The heat of adsorption stays nearly constant at 405 kJ/mol up to a coverage of 0.6 ML, which is ascribed to Ca diffusing below the surface and forming CaS clusters by abstraction of sulfur from the thiophene rings, based on XPS and LEIS data. The heat of adsorption then decreases gradually until it reaches the heat of sublimation of bulk Ca, 178 kJ/mol, by 4 ML; this is attributed to the formation of 3D Ca islands on top of the polymer, which eventually coalesce into a continuous Ca film by 11 ML. The heat of reaction versus coverage and the ultimate depth up to which the Ca atoms react with the polymer thiophene groups (approximately 3 nm) are nearly independent of electron damage, except for a difference in the heat of adsorption below 0.1 ML associated with defects or impurities. The increase in initial sticking probability caused by electron damage is attributed to stronger bonding of Ca adatoms to unsaturated versus

  10. Literature review of clinical results of total skin electron irradiation (TSEBT) of mycosis fungoides in adults

    PubMed Central

    Moraes, Fabio Ynoe de; Carvalho, Heloisa de Andrade; Hanna, Samir Abdallah; Silva, João Luis Fernandes da; Marta, Gustavo Nader

    2013-01-01

    Background Mycosis fungoides (MF) is an extranodal, indolent non-Hodgkin lymphoma of T cell origin. Even with the establishment of MF staging, the initial treatment strategy often remains unclear. Aim The aim of this study was to review the clinical results of total skin electron beam therapy (TSEBT) for MF in adults published in English language scientific journals searched in Pubmed/Medline database until December 2012. Results MF is very sensitive to radiation therapy (RT) delivered either by photons or by electrons. In limited patches and/or plaques local electron beam irradiation results in good outcomes besides the fact of not being superior to other modalities. For extensive patches and/or plaques data suggest that TSEBT shows superior response rates. The cutaneous disease presentation is favorably managed with radiotherapy due to its ability to treat the full thickness of deeply infiltrated skin. For generalized erythroderma presentation, TSEBT seems to be an appropriate initial therapy. For advanced disease, palliation, or recurrence after the first radiotherapy treatment course, TSEBT may still be beneficial, with acceptable toxicity. Recommended dose is 30–36 Gy delivered in 6–10 weeks. Conclusion TSEBT can be used to treat any stage of MF. It also presents good tumor response with symptoms of relief and a palliative effect on MF, either after previous irradiation or failure of other treatment strategies. PMID:24936326

  11. Investigation of VLSI Bipolar Transistors Irradiated with Electrons, Ions and Neutrons for Space Application

    NASA Astrophysics Data System (ADS)

    D'Angelo, P.; Fallica, G.; Galbiati, A.; Mangoni, R.; Modica, R.; Pensotti, S.; Rancoita, P. G.

    2006-04-01

    A systematic investigation of radiation effects on a BICMOS technology manufactured by STM has been undertaken. Bipolar transistors were irradiated by neutrons, C, Ar and Kr ions, and recently by electrons. Fast neutrons, as well as other types of particles, produce defects mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs (the so-called Frenkel pairs). Although imparted doses differ largely, the experimental results indicate that the gain (β) variation is mostly related to the non-ionizing energy-loss (NIEL) deposition for neutrons, ions and electrons. The variation of the inverse of the gain degradation, Δ(1/β), is found to be linearly related (as predicted by the Messenger-Spratt equation for neutron irradiations) to the concentrations of the Frenkel pairs generated independently of the kind of incoming particle. For space applications, this linear dependence on the concentration of Frenkel pairs allows to evaluate the total amount of the gain degradation of VLSI components due to the flux of charged particles during the full life of operation of any pay-load. In fact, the total amount of expected Frenkel pairs can be estimated taking into account the isotopic spectra. It has to be point out that in cosmic rays there is relevant flux of electrons and isotopes up to Ni, which are within the range of particles presently investigated.

  12. Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

    PubMed Central

    Yu, Xuechao; Shen, Youde; Liu, Tao; Wu, Tao (Tom); Jie Wang, Qi

    2015-01-01

    Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices. PMID:26152225

  13. Structural changes in graphene oxide thin film by electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Tyagi, Chetna; Lakshmi, G. B. V. S.; Kumar, Sunil; Tripathi, Ambuj; Avasthi, D. K.

    2016-07-01

    Although we have a whole class of 2D materials, graphene has drawn much attention for its excellent electronic, optical, thermal and mechanical properties. Recent researches have shown its large scale production by the reduction of graphene oxide either thermally, chemically or electrochemically. Although the structure of graphene oxide is inhomogeneous and hence complicated due to the presence of organic moieties e.g. epoxy, carboxylic acid, hydroxyl groups etc., its properties can be tuned by reduction according to desired application. The aim of this work is to synthesize continuous thin film of graphene oxide using commercially available graphene oxide solution and to study its reduction by 25 keV electron beam irradiation at fluences varying from 2 × 1011 to 2 × 1013 e-/cm2. Our studies using X-ray diffraction, Raman microscopy and UV-Vis spectroscopy showed that electron-beam irradiation is an effective tool for reduction of graphene oxide and for tuning its band gap.

  14. Comparison Study on Changes of Antigenicities of Egg Ovalbumin Irradiated by Electron Beam or X-Ray

    PubMed Central

    Kim, Mi-Jung; Hwang, Young-Jung

    2014-01-01

    This study was conducted to compare the effects of two forms of radiation (electron and X-ray; generated by an electron beam accelerator) on the conformation and antigenic properties of hen’s egg albumin, ovalbumin (OVA), which was used as a model protein. OVA solutions (2.0 mg/mL) were individually irradiated by electron beam or X-ray at the absorbed doses of 0 (control), 2, 4, 6, 8, and 10 kGy. No differences between the two forms of radiation on the structural properties of OVA were shown by spectrometric and electrophoretic analyses. The turbidity of OVA solution increased and the main OVA bands on polyacrylamide gels disappeared after irradiation, regardless of the radiation source. In competitive indirect enzyme-linked immunosorbent assay, OVA samples irradiated by electron beam or X-ray showed different immunological responses in reactions with monoclonal and polyclonal antibodies (immunoglobulin G) produced against non-irradiated OVA. The results indicate that electron beam irradiation and X-ray irradiation produced different patterns of structural changes to the OVA molecule. PMID:26761489

  15. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J.; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-01

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV–visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3–0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  16. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria.

    PubMed

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-17

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F(+) centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections. PMID:27319289

  17. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria.

    PubMed

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-17

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F(+) centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  18. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J.; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-01

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  19. Color-Center Production and Formation in Electron-Irradiated Magnesium Aluminate Spinel and Ceria

    DOE PAGES

    Costantini, Jean-Marc; Lelong, Gerald; Guillaumet, Maxime; Weber, William J.; Takaki, Seiya; Yasuda, Kazuhiro

    2016-06-20

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (100) or (110) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0-MeV and 2.5-MeV electrons in a high fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F+ centers (neutral and singly-ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in colour-centre formation were observed for the two crystal orientations. Using calculationsmore » of displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at RT. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200°C with almost full bleaching at 600°C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub band-gap absorption feature peaked at ~3.1 eV was recorded for 2.5-MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.« less

  20. Generation and Transport of Fast Electrons in Laser Irradiated Targets at Relativistic Intensities

    NASA Astrophysics Data System (ADS)

    Amiranoff, F.; Baton, S. D.; Gremillet, L.; Guilbaud, O.; Koenig, M.; Martinolli, E.; Santos, J. J.; Le Gloahec, M. Rabec; Rousseaux, C.; Hall, T.

    2002-10-01

    The transport of relativistic electrons in solid targets irradiated by a short laser pulse at relativistic intensities has been studied both experimentally and numerically. A Monte-Carlo collision code takes into account individual collisions with the ions and electrons in the target. A 3D-hybrid code takes into account these collisions as well as the generation of electric and magnetic fields and the self-consistent motion of the electrons in these fields. It predicts a magnetic guiding of a fraction of the fast electron current over long distances and a localized heating of the material along the propagation axis. In experiments performed at LULI on the 100 TW laser facility, several diagnostics have been implemented to diagnose the geometry of the fast electron transport and the target heating. The typical conditions were: E1 less-than-or-equal 20 J, lambda = 1 mum, tau approximately 300 fs, I approximately 1018-5.1019W/cm2. The results indicate a modest heating of the target (typically 20-40 eV over 20 mum to 50 mum), consistent with an acceleration of the electrons inside a wide aperture cone along the laser axis.

  1. Postmastectomy Electron Beam Chest Wall Irradiation in Women With Breast Cancer: A Clinical Step Toward Conformal Electron Therapy

    SciTech Connect

    Kirova, Youlia M. Campana, Francois; Fournier-Bidoz, Nathalie; Stilhart, Anne; Dendale, Remi; Bollet, Marc A.; Fourquet, Alain

    2007-11-15

    Purpose: Electron beam radiotherapy of the chest wall with or without lymph node irradiation has been used at the Institut Curie for >20 years. The purpose of this report was to show the latest improvements of our technique developed to avoid hot spots and improve the homogeneity. Methods and Materials: The study was split into two parts. A new electron irradiation technique was designed and compared with the standard one (dosimetric study). The dose distributions were calculated using our treatment planning software ISIS (Technologie Diffusion). The dose calculation was performed using the same calculation parameters for the new and standard techniques. Next, the early skin toxicity of our new technique was evaluated prospectively in the first 25 patients using Radiation Therapy Oncology Group criteria (clinical study). Results: The maximal dose found on the five slices was 53.4 {+-} 1.1 Gy for the new technique and 59.1 {+-} 2.3 Gy for the standard technique. The hot spots of the standard technique plans were situated at the overlap between the internal mammary chain and chest wall fields. The use of one unique field that included both chest wall and internal mammary chain volumes solved the problem of junction. To date, 25 patients have been treated with the new technique. Of these patients, 12% developed Grade 0, 48% Grade 1, 32% Grade 2, and 8% Grade 3 toxicity. Conclusions: This report describes an improvement in the standard postmastectomy electron beam technique of the chest wall. This new technique provides improved target homogeneity and conformality compared with the standard technique. This treatment was well tolerated, with a low rate of early toxicity events.

  2. Influences of surfactants on the preparation of copper nanoparticles by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Zhou, Ruimin; Wu, Xinfeng; Hao, Xufeng; Zhou, Fei; Li, Hongbin; Rao, Weihong

    2008-02-01

    Electron beam radiation was applied to prepare nano-size copper in water system using polyvinyl alcohol, sodium dodecyl benzene sulfonate, gluten and polyethylene glycol as the surfactants, respectively. The irradiated products were characterized by XRD, TEM and LSPSDA. The XRD and TEM showed that relative pure copper products with an average size of 20 nm, 40 nm and 20 nm can be obtained by using gluten, PEG and SDBS as surfactant, respectively. An admixture of copper and cuprous oxide was obtained in PVA system. The LSPSDA showed that the size of the Cu nanoparticles decreased with increasing the glutin concentration.

  3. Conductors, semiconductors, and insulators irradiated with short-wavelength free-electron laser

    NASA Astrophysics Data System (ADS)

    Krzywinski, J.; Sobierajski, R.; Jurek, M.; Nietubyc, R.; Pelka, J. B.; Juha, L.; Bittner, M.; Létal, V.; Vorlíček, V.; Andrejczuk, A.; Feldhaus, J.; Keitel, B.; Saldin, E. L.; Schneidmiller, E. A.; Treusch, R.; Yurkov, M. V.

    2007-02-01

    The results of a study of irreversible changes induced at surfaces of metals, semiconductors, and insulators by extreme ultraviolet (λ<100nm) ultrashort pulses provided by TESLA Test Facility Free-Electron Laser, Phase 1 (TTF1 FEL) are reported and discussed. The laser was tuned at 86, 89, and 98nm during the experiments reported here. Energy spectra of ions ejected from the irradiated surfaces are also reported. Special attention is paid to the difference in the ablation behavior of (semi)conductors and insulators that we have observed. The difference is dramatic, while the absorption coefficients are similar for all materials at the TTF1 FEL wavelength.

  4. Effects of Light and Electron Beam Irradiation on Halide Perovskites and Their Solar Cells.

    PubMed

    Klein-Kedem, Nir; Cahen, David; Hodes, Gary

    2016-02-16

    Hybrid alkylammonium lead halide perovskite solar cells have, in a very few years of research, exceeded a light-to-electricity conversion efficiency of 20%, not far behind crystalline silicon cells. These perovskites do not contain any rare element, the amount of toxic lead used is very small, and the cells can be made with a low energy input. They therefore already conform to two of the three requirements for viable, commercial solar cells-efficient and cheap. The potential deal-breaker is their long-term stability. While reasonable short-term (hours) and even medium term (months) stability has been demonstrated, there is concern whether they will be stable for the two decades or more expected from commercial cells in view of the intrinsically unstable nature of these materials. In particular, they have a tendency to be sensitive to various types of irradiation, including sunlight, under certain conditions. This Account focuses on the effect of irradiation on the hybrid (and to a small degree, all-inorganic) lead halide perovskites and their solar cells. It is split up into two main sections. First, we look at the effect of electron beams on the materials. This is important, since such beams are used for characterization of both the perovskites themselves and cells made from them (electron microscopy for morphological and compositional characterization; electron beam-induced current to study cell operation mechanism; cathodoluminescence for charge carrier recombination studies). Since the perovskites are sensitive to electron beam irradiation, it is important to minimize beam damage to draw valid conclusions from such measurements. The second section treats the effect of visible and solar UV irradiation on the perovskites and their cells. As we show, there are many such effects. However, those affecting the perovskite directly need not necessarily always be detrimental to the cells, while those affecting the solar cells, which are composed of several other phases

  5. Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source

    SciTech Connect

    Andreani, C.; Pietropaolo, A.; Salsano, A.; Gorini, G.; Tardocchi, M.; Paccagnella, A.; Gerardin, S.; Frost, C. D.; Ansell, S.; Platt, S. P.

    2008-03-17

    The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 10{sup 7}. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

  6. Synergistic Effects of Combined Electron Beam and Microwave Irradiation on Microorganisms Inactivation

    NASA Astrophysics Data System (ADS)

    Craciun, Gabriela D.; Martin, Diana I.; Manaila, Elena N.; Togoe, Iulian I.; Ighigeanu, Daniel I.; Iacob, Nicusor I.; Ighigeanu, Adelina I.; Oproiu, Constantin V.

    2007-04-01

    Comparative results obtained by using separate and combined electron beam (EB) and microwave (MW) on microorganisms inactivation in natural products such as minced beef, wheat bran, wheat flour and sewage sludge are presented. The combination of advantages of both, EB and MW, in microbiological decontamination process, i.e. the EB high efficiency and MW high selectivity and volumetric heating assures higher material microbiological safety, extends the kind range of microorganisms to be inactivated, reduces the absorbed dose level and irradiation time, and decreases the process costs.

  7. Monitoring of Irradiated Food Products Marketed in Italy and Evaluation of Electron Spin Resonance Signal Sensitivity of Experimentally Irradiated Fish Scales

    PubMed Central

    Carosielli, Leonardo; Mangiacotti, Michele; Chiaravalle, Eugenio; Smaldone, Giorgio; Anastasio, Aniello

    2014-01-01

    Many countries, in order to authorise the use of food irradiation, claim the availability of methods to detect the occurred treatment in addition to the respect of safe use of this technology. Among physical methods, the electron spin resonance (ESR) measuring the number of free radicals that are formed during irradiation can be applied only to those foods with cellulose, a crystalline or bone structure, in which free radicals have a shelf life greater than irradiated product. The aim of this study was to highlight an irradiation treatment in European and extra-European foods marketed in Southern Italy by the means of ESR technique. Furthermore, in order to optimise the preparation procedures the efficacy of the above mentioned method in fish scales experimentally irradiated has been evaluated. From February to September 2012, a total number of 83 samples of food products of animal and plant origin were taken at the border inspection post and at retail market and finally analysed. At the same time, the scales of grouper and barracuda have been experimentally irradiated at 0.5 kGy and were subsequently analysed using ESR. Results showed 5 frog legs out of 83 samples positive for treatment and confirm the applicability of ESR also for fish scales. PMID:27800329

  8. Electron paramagnetic resonance of natural and gamma-irradiated alunite and kaolin mineral powders

    NASA Astrophysics Data System (ADS)

    Koksal, F.; Koseoglu, R.; Saka, I.; Basaran, E.; Sener, F.

    2004-06-01

    Natural alunite and kaolin minerals obtained from West Anatolia were investigated by electron paramagnetic resonance (EPR) in natural and gamma-irradiated states at room temperature and at 113 K. The paramagnetic centres at ambient temperature in natural alunite were attributed to the (C) over dot H 2OH, (C) over dot O-3(-), (S) over dot O-2(-), (C) over dot O-2(-) and [AlO4 ](0) radicals. In natural kaolin, the paramagnetic centres were attributed to the (C) over dot O-3(-), (S) over dot O-2(-) (C) over dot O-2(-) and [AlO4](0) radicals. The gamma-irradiation does not produce any detectable effects on these radicals. At 113 K, the lines for (C) over dot H2OH could not be observed well, probably due to the anisotropic behaviour of the hyperfine interaction of the methylene protons, but the lines for [AlO4](0) centres were found to be perfectly observable at above 20 mW microwave power in both alunite and kaolin powders before and after gamma-irradiation. The EPR parameters of the observed paramagnetic centres were reported.

  9. Structure-property relationships of electron-beam-irradiated monomeric and polymeric systems

    SciTech Connect

    Kim, Ha Chul.

    1989-01-01

    Structure-property relationships were investigated for electron beam (EB) irradiated monomeric and polymeric systems. The objectives were to study the feasibility of preparing systems of potential application, and to characterize these systems in terms of structure-property behavior. In this thesis, the basic theories on radiation chemistry were first reviewed. Next, five different studies on the application of EB radiation were discussed. In the first study on the surface modification of the methacyclic acid derivative of the glycidyl ether of bis-phenol A(bis-GMA) substrates, considerable changes in wetting characteristics were observed using functionalized poly(dimethyl siloxane) (PDMS) oligomers as surface modifiers. The second subject was utilized to cross-linked caprolactone-allyl glycidyl ether(CL-AGE) copolymers. EB radiation was utilized to crosslink these materials at various temperatures both above and below the crystalline melting point. In the third study, models of time-temperature-energy(TTE) diagrams in an idealized EB radiation curing system were developed to help provide a conceptual understanding of the TTE relationship. The fourth study focused on the effects of EB irradiation on the mechanical and thermal properties of poly(phenylene sulfide). In the fifth study, two systems(symmetric and asymmetric) based on the controlled distribution of bis-GMA within a crosslinked nitrile rubber(NBR) network were prepared utilizing EB irradiation.

  10. An electron spin resonance study of γ-ray irradiated ginseng

    NASA Astrophysics Data System (ADS)

    Nakamura, Hideo; Ukai, Mitsuko; Shimoyama, Yuhei

    2006-03-01

    Using electron spin resonance (ESR) spectroscopy, we revealed the presence of four radical species in γ-ray irradiated ginseng ( Agaliaceae). Before irradiation, the representative ESR spectrum of ginseng is composed of a sextet centered at g = 2.0, a sharp singlet at the same g-value, and a singlet at about g = 4.0. The first one is attributable to a hyperfine (hf) signal of Mn 2+ ion (hf constant: 7.4 mT). The second one is due to an organic free radical. The third one is originated from Fe 3+. Upon γ-ray irradiation, a new ESR (the fourth) signal was detectable in the vicinity of g = 2.0 region. The progressive saturation behaviors of the ESR signals at various microwave power levels were indicative of different relaxation time for those radicals. The anisotropic ESR spectra were detected by the angular rotation of the sample tube. This is due to the existence of anisotropic microcrystalline in the ginseng powder sample.

  11. Electron magnetic resonance study of gamma-irradiated poly(lactide-co-glycolide) microspheres.

    PubMed

    Claybourn, Mike; Gray, Helen; Murphy, Damien M; Purnell, Ian J; Rowlands, Christopher C

    2003-09-01

    A series of poly(lactide-co-glycolide) samples of compositions ranging from (75:25) to (65:35) to (50% (65:35):50% (50:50)) were gamma-irradiated under ambient conditions in air. The irradiation doses used were 15, 20, 25, and 30 kGy. The generation of radicals resulting from the gamma-irradiation was confirmed using EPR. Two major radical species were observed and identified as centered at alkyl and alkyl peroxy groups. The indication from the X-band (9 GHz) frequencies showed that alkyl radicals gave rise to a quartet hyperfine pattern. However, measurements performed at higher W-band frequencies (90 GHz) showed that the X-band spectra are actually a composite profile arising from a series of overlapping individual resonances. Using combined EPR and ENDOR (Electron-Nuclear DOuble Resonance) measurements, an alkyl peroxy radical was identified. For increasing glycolide concentration from 75:25 to the 50:50 blend, there was a factor of 7 increase in the concentration of radicals A and B. Furthermore, both radical species were found to be stable for several weeks after storage at ambient temperature conditions. At elevated temperatures and humidities, radical stability decreased--the decay rate was estimated at approximately 3x10(-8) mol K(-1). The stability characteristics of the radicals under different conditions are attributed to changes in the morphology of the polymer. PMID:12932720

  12. The network and properties of the NR/SBR vulcanizate modified by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Shen, Jing; Wen, Shipeng; Du, Yishi; Li, Ning; Zhang, Liqun; Yang, Yusheng; Liu, Li

    2013-11-01

    A natural rubber/styrene butadiene rubber (NR/SBR) vulcanizate filled with carbon black was modified by high-energy electron beam (EB) irradiation in this work. The crosslinked structure was studied by a special chemical probe method. The influence of EB irradiation on mechanical properties, filler network, and dynamic properties including abrasion resistance, rolling resistance, and wet skid resistance was also investigated. The results revealed that the crosslink structure significantly changed after EB treatment, indicating that the amount of poly- and di-sulfide crosslinked bonds decreased and that of mono-sulfide bonds increased. The polymer-filler interaction was enhanced after EB irradiation. An EB dose of 600 kGy reduced the abrasion loss of the NR/SBR vulcanizate, and one of 300 kGy reduced the rolling resistance by 11.4%. Meanwhile, EB doses below 200 kGy had no obvious effect on the wet skid resistance. This EB-modified NR/SBR vulcanizate can be used to prepare high-performance tires with good abrasion resistance and low rolling resistance.

  13. Electron paramagnetic resonance in irradiated fingernails: variability of dose dependence and possibilities of initial dose assessment.

    PubMed

    Reyes, R A; Romanyukha, Alexander; Olsen, C; Trompier, F; Benevides, L A

    2009-08-01

    The results of electron paramagnetic resonance (EPR) measurements in irradiated fingernails are presented. In total, 83 samples of different fingernails were studied. Five different groups of samples were selected based on the collection time of fingernail samples, their level of mechanical stress, and the number and size of clippings: (1) recently (<24 h) cut, irradiated and measured with EPR without any treatment of samples, and with rigorous control of size and number of clippings (stressed-fresh, controlled); (2) recently (<24 h) cut, irradiated and measured with EPR after application of a special treatment (10 min of water soaking, 5 min of drying time) to reduce the mechanical stress caused by cutting the samples, and with rigorous control of size and number of clippings (unstressed-fresh, controlled); (3) previously (>24 h) cut, stored at room temperature, additionally cut into small pieces immediately prior to study, irradiated and measured with EPR without any treatment of samples, and with rigorous control of size and number of clippings (stressed-old, controlled); (4) previously (>24 h) cut, stored at room temperature, additionally cut into small pieces immediately prior to the study, irradiated and measured with EPR after application of a special treatment to reduce mechanical stress caused by cut, and with rigorous control of size and number of clippings (unstressed-old, controlled); and (5) recently (<24 h) cut, irradiated and measured with EPR after application of a special treatment to reduce the mechanical stress caused by cut, and without rigorous control of size and number of clippings (unstressed-fresh, uncontrolled). Except for the fifth selected group, variability of the dose dependence inside all groups was found to be not statistically significant, although the variability among the different groups was significant. Comparison of the mean dose dependences obtained for each group allowed selection of key factors responsible for radiation

  14. Application of Electron-Beam Irradiation Combined with Aging for Improvement of Microbiological and Physicochemical Quality of Beef Loin

    PubMed Central

    Yim, Dong-Gyun; Jo, Cheorun

    2016-01-01

    The combined effects of irradiation and aging temperature on the microbial and chemical quality of beef loin were investigated. The samples were vacuum-packaged, irradiated at 0 or 2 kGy using electron-beam (EB), and stored for 10 d at different aging temperatures (2, 14, or 25℃). The microbial growth, shear values, meat color, and nucleotide-related flavor compounds of the samples were analyzed. The irradiation effect on inactivation of foodborne pathogens was also investigated. The population of Listeria monocytogenes and Escherhia coli O157:H7 inoculated in beef samples decreased in proportion to the irradiation dose. Irradiation reduced the total aerobic bacteria (TAB) over the storage, but higher aging temperature increased the TBA. Thus TAB increased sharply in non-irradiated and high temperature-aged (14, 25℃) beef samples after 5 d. With increasing aging temperature and aging time, shear force values decreased. Lipid oxidation could be reduced by short aging time at low aging temperature. The color a* values of the irradiated beef were lower than those of the non-irradiated throughout the aging period. As aging period and temperature increased, IMP decreased and hypoxanthine increased. Considering microbial and physicochemical properties, irradiation can be used for raw beef to be aged at relatively high temperature to shorten aging time and cost. PMID:27194930

  15. Application of Electron-Beam Irradiation Combined with Aging for Improvement of Microbiological and Physicochemical Quality of Beef Loin.

    PubMed

    Yim, Dong-Gyun; Jo, Cheorun; Kim, Hyun Cheol; Seo, Kang Seok; Nam, Ki-Chang

    2016-01-01

    The combined effects of irradiation and aging temperature on the microbial and chemical quality of beef loin were investigated. The samples were vacuum-packaged, irradiated at 0 or 2 kGy using electron-beam (EB), and stored for 10 d at different aging temperatures (2, 14, or 25℃). The microbial growth, shear values, meat color, and nucleotide-related flavor compounds of the samples were analyzed. The irradiation effect on inactivation of foodborne pathogens was also investigated. The population of Listeria monocytogenes and Escherhia coli O157:H7 inoculated in beef samples decreased in proportion to the irradiation dose. Irradiation reduced the total aerobic bacteria (TAB) over the storage, but higher aging temperature increased the TBA. Thus TAB increased sharply in non-irradiated and high temperature-aged (14, 25℃) beef samples after 5 d. With increasing aging temperature and aging time, shear force values decreased. Lipid oxidation could be reduced by short aging time at low aging temperature. The color a* values of the irradiated beef were lower than those of the non-irradiated throughout the aging period. As aging period and temperature increased, IMP decreased and hypoxanthine increased. Considering microbial and physicochemical properties, irradiation can be used for raw beef to be aged at relatively high temperature to shorten aging time and cost. PMID:27194930

  16. Synergistic Effects of Electron-beam Irradiation and Leek Extract on the Quality of Pork Jerky during Ambient Storage

    PubMed Central

    Kim, Hyun-Joo; Kang, Mingu; Yong, Hae In; Bae, Young Sik; Jung, Samooel; Jo, Cheorun

    2013-01-01

    To investigate the synergistic effect(s) of electron-beam (EB) irradiation and leek (Allium tuberosum Rottler) extract on the quality of pork jerky during ambient storage, we irradiated prepared pork jerky samples (control and samples with 0.5% and 1.0% leek extract) with EB technology at doses of 0, 1, 2, and 4 kGy, stored them for 2 months at 25°C, and analyzed them. Water activity was 0.73 to 0.77 in non-irradiated samples, and no significant difference in the water activity was observed between the samples treated with leek and the control. The total aerobic bacterial count was significantly decreased with an increase in the irradiation dose and leek extract addition when compared to that of the control (4.54±0.05 log CFU/g). Further, the Hunter color values (L*, a*, and b*) were found to be significantly decreased following leek extract addition and EB irradiation. However, the color values, especially the a* value of the irradiated samples significantly increased during storage. Notably, increasing the EB irradiation dose enhanced the peroxide value. Sensory evaluation revealed that irradiation decreased flavor and overall acceptability. Our findings suggest the use of EB irradiation in combination with leek extract to improve the microbiological safety of pork jerky. However, in order to meet market requirements, novel methods to enhance the sensory quality of pork jerky are warranted. PMID:25049828

  17. Electron spin resonance study of γ-irradiated Anatolian chickpea (Cicer arietinum L.)

    NASA Astrophysics Data System (ADS)

    Ayda, Canan; Engin, B. I. R. O. L.; Polat, Mustafa; Aydin, Talat

    In this study, an electron spin resonance (ESR) investigation on γ-irradiated chickpea cultivated in Turkey is reported in detail. ESR spectra of unirradiated (control) chickpea were composed of an equally spaced sextet originating from the presence of Mn2+ ions and a single weak resonance signal both centered at gD2.0054±0.0006. Although irradiation was found to have no effect on the Mn2+ signals, it caused a noteworthy increase in free radical signal intensity of chickpea in the studied dose range of (0.1-4.5 kGy). In addition, the ESR spectrum of irradiated chickpea recorded at low scan range (10 mT) showed that there were more than one radical species, having different spectral features, contributing to the central resonance signal. From this point of view, we focussed on the free radical signal in the present study. The area under the ESR absorption curve which is related to the free radical concentration was determined from the experimental spectra recorded throughout the study, and its variation with microwave power, radiation dose, storage time and temperature was investigated in detail. Free radical concentration was observed to decay very fast within the first 15 days after the irradiation cessation and little thereafter. At the end of the storage period (60 days), the free radical concentration is still higher than that of the control (unirradiated) sample. The decay of free radical concentration at room and high temperatures were described well by the sum of three second-order decay functions representing three different radical species (A, B and C). The activation energies of these radicals, evaluated by Arrhenius analysis, are in the order EC>EB>EA. Simulation calculations have shown that three radical species (A, B and C) of different spectral parameters were found to best explain the experimental values.

  18. A comparative study on the effects of electron beam irradiation on imidacloprid-resistant and -susceptible Aphis gossypii (Hemiptera: Aphididae)

    NASA Astrophysics Data System (ADS)

    Yun, Seung-Hwan; Koo, Hyun-Na; Lee, Seon-Woo; Kim, Hyun Kyung; Kim, Yuri; Han, Bumsoo; Kim, Gil-Hah

    2015-07-01

    The melon and cotton aphid, Aphis gossypii, is a polyphagous insect pest. This study compared the development, reproduction, DNA damage, recovery, and gene expression in imidacloprid-resistant (IMI-R) and -susceptible (S) strains of A. gossypii by electron beam irradiation. When 1st instar nymphs were irradiated with 100 Gy, the fecundity (nymphs of F1 generation) of the resultant adults were completely inhibited. When adults were irradiated with 200 Gy, the number of total 1st instar nymphs produced per adult was 3.0±1.7 and 1.9±1.4 in the S and IMI-R strains, respectively, but adult development was completely suppressed. However, electron beam irradiation did not affect adult longevity in either the S or IMI-R strain. There was no statistically significant difference between the effect of irradiation on the S and IMI-R strains. Therefore, electron beam irradiation at 200 Gy could be used as a phytosanitary irradiation treatment for both S and IMI-R strains of A. gossypii. The DNA damage caused by electron beam irradiation was evaluated by an alkaline comet assay. Exposure to an electron beam (50 Gy) induced DNA damage that was repaired to a similar level as the untreated control group (0 Gy) over time. However, at more than 100 Gy, the DNA damage was not completely repaired. The expression of P450, HSP70, cuticle protein, and elongation factor genes were higher in the IMI-R strain than in the S strain.

  19. Defect generation in Cu(In,Ga)Se2 heterojunction solar cells by high-energy electron and proton irradiation

    NASA Astrophysics Data System (ADS)

    Jasenek, A.; Rau, U.

    2001-07-01

    We investigate irradiation-induced defects in high-efficiency Cu(In,Ga)Se2/CdS/ZnO heterojunction solar cells after electron irradiation with energies of 0.5, 1, and 3 MeV and after 4 MeV proton irradiation. We use electron and proton fluences of more than 1018cm-2 and up to 1014cm-2, respectively. The reduction of the solar cell efficiency in all experiments is predominantly caused by a loss ΔVOC of the open circuit voltage VOC. An analytical model describes ΔVOC in terms of radiation-induced defects enhancing recombination in the Cu(In,Ga)Se2 absorber material. From our model, we extract defect introduction rates for recombination centers in Cu(In,Ga)Se2 for the respective particles and energies. We directly monitor the defect generation of these radiation-induced defects by admittance spectroscopy. The decrease of effective doping density in the Cu(In,Ga)Se2 absorber layer under particle irradiation is analyzed with capacitance voltage measurements at low temperatures. Furthermore, data on the relative damage coefficients for high-energy electron irradiation in Cu(In,Ga)Se2 solar cells are presented. All data, from electron as well as proton irradiations, merge to a single characteristic degradation curve.

  20. 78 FR 34565 - Irradiation in the Production, Processing, and Handling of Animal Feed and Pet Food; Electron...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ..., and Handling of Animal Feed and Pet Food; Electron Beam and X-Ray Sources for Irradiation of Poultry... generated from machine sources at energy levels not to exceed 10 million electron volts (MeV); (3) X-rays... this chapter; or (4) X-rays generated from machine sources using tantalum or gold as the...

  1. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    SciTech Connect

    Bhat, Sathyanarayana Rao, Asha; Krishnan, Sheeja; Sanjeev, Ganesh; Suresh, E. P.

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  2. The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon.

    PubMed

    Khara, Galvin S; Murphy, Samuel T; Daraszewicz, Szymon L; Duffy, Dorothy M

    2016-10-01

    The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat. PMID:27501917

  3. The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon.

    PubMed

    Khara, Galvin S; Murphy, Samuel T; Daraszewicz, Szymon L; Duffy, Dorothy M

    2016-10-01

    The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.

  4. The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

    NASA Astrophysics Data System (ADS)

    Khara, Galvin S.; Murphy, Samuel T.; Daraszewicz, Szymon L.; Duffy, Dorothy M.

    2016-10-01

    The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.

  5. Measurements of Electron Transport in Foils Irradiated with a Picosecond Time Scale Laser Pulse

    SciTech Connect

    Brown, C. R. D.; Hoarty, D. J.; James, S. F.; Swatton, D.; Hughes, S. J.; Morton, J. W.; Guymer, T. M.; Hill, M. P.; Chapman, D. A.; Andrew, J. E.; Comley, A. J.; Shepherd, R.; Dunn, J.; Chen, H.; Schneider, M.; Brown, G.; Beiersdorfer, P.; Emig, J.

    2011-05-06

    The heating of solid foils by a picosecond time scale laser pulse has been studied by using x-ray emission spectroscopy. The target material was plastic foil with a buried layer of a spectroscopic tracer material. The laser pulse length was either 0.5 or 2 ps, which resulted in a laser irradiance that varied over the range 10{sup 16}-10{sup 19} W/cm{sup 2}. Time-resolved measurements of the buried layer emission spectra using an ultrafast x-ray streak camera were used to infer the density and temperature conditions as a function of laser parameters and depth of the buried layer. Comparison of the data to different models of electron transport showed that they are consistent with a model of electron transport that predicts the bulk of the target heating is due to return currents.

  6. Conversion of stacking fault tetrahedra to voids in electron irradiated Fe-Cr-Ni

    NASA Astrophysics Data System (ADS)

    Kojima, S.; Sano, Y.; Yoshiie, T.; Yoshida, N.; Kiritani, M.

    1986-11-01

    Electron irradiations of the austenitic Fe-13Cr-14Ni alloy were performed with a high voltage electron microscope at temperatures between room temperature and 650 K. Formation of stacking fault tetrahedra, voids and dislocation loops was observed as vacancy clusters. At the lower temperatures, the dominant vacancy clusters were tetrahedra and at the higher temperatures, voids were dominant. In the temperature range at which both tetrahedra and voids were coexistent, conversion of tetrahedra to voids were observed. These results are interpreted as the preferable nucleation of voids at the site of tetrahedra. Local effects of dilatation field at the corner of tetrahedra and the segregation of solute atoms are considered to enhance the nucleation. Clustered defects which are considered to be stacking fault tetrahedra that are formed with D-T fusion neutrons in SUS 316 stainless steel are suggested as the preferable site for void nucleation.

  7. Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

    NASA Astrophysics Data System (ADS)

    Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  8. Influence of radiation defects on electrical losses in silicon diodes irradiated with electrons

    SciTech Connect

    Poklonski, N. A. Gorbachuk, N. I.; Shpakovski, S. V.; Lastovskii, S. B.; Wieck, A.

    2010-03-15

    Silicon diodes with a p{sup +}-n junction irradiated with 3.5-MeV electrons (the fluence ranged from 10{sup 15} to 4 x 10{sup 16} cm{sup -2}) have been studied. It is established that the dependence of the tangent of the angle of electrical losses tan{delta} on the frequency f of alternating current in the range f = 10{sup 2}-10{sup 6} Hz is a nonmonotonic function with two extrema: a minimum and a maximum. Transformation of the dependences tan{delta}(f) as the electron fluence and annealing temperature are increased is caused by a variation in the resistance of n-Si (the base region of the diodes) as a result of accumulation (as the fluence is increased) or disappearance and reconfiguration (in the course of annealing) of radiation defects. The role of time lag of the defect recharging in the formation of tan{delta}(f) is insignificant.

  9. Electron irradiation induced reduction of the permittivity in chalcogenide glass (As{sub 2}S{sub 3}) thin film

    SciTech Connect

    San-Roman-Alerigi, Damian P.; Zhang Yaping; Benslimane, Ahmed; Ng, Tien K.; Ooi, Boon S.; Anjum, Dalaver H.; Yang Xiaoming; Hedhili, Mohamed N.; Alsunaidi, Mohammad

    2013-01-28

    In this paper, we investigate the effect of electron beam irradiation on the dielectric properties of As{sub 2}S{sub 3} chalcogenide glass. By means of low-loss electron energy loss spectroscopy, we derive the permittivity function, its dispersive relation, and calculate the refractive index and absorption coefficients under the constant permeability approximation. The measured and calculated results show a heretofore unseen phenomenon: a reduction in the permittivity of {>=}40%. Consequently a reduction of the refractive index of 20%, hence, suggests a conspicuous change in the optical properties of the material under irradiation with a 300 keV electron beam. The plausible physical phenomena leading to these observations are discussed in terms of the homopolar and heteropolar bond dynamics under high energy absorption. The reported phenomena, exhibited by As{sub 2}S{sub 3}-thin film, can be crucial for the development of photonics integrated circuits using electron beam irradiation method.

  10. Raman and electron microscopy analysis of carbon nanotubes exposed to high power laser irradiance

    SciTech Connect

    Ramadurai, Krishna; Cromer, Christopher L.; Lehman, John H.; Dillon, Anne C.; Mahajan, Roop L.

    2009-05-01

    High power laser radiometry requires efficient and damage-resistant detectors. The current study explores the evolving nature of carbon nanotube coatings for such detectors upon their exposure to incrementally increasing laser power levels. Electron microscopy images along with the D-band to G-band intensity ratios from the Raman spectra from eight irradiance levels are used to evaluate changes before and after the exposure. Electron microscopy images of the exposed multiwalled carbon nanotubes revealed the formation of intermittent pockets of moundlike structures at high power densities exceeding 11 kW/cm{sup 2}. Raman spectroscopy measurements also demonstrated higher values for the ratio of the D-band intensity to that of the G-band, suggesting the possible transformation of nanotubes into structurally different forms of carbon. Exposure to a sample of single-walled nanotubes did not demonstrate the evolution of structural changes, which could be due in part to the higher irradiance levels relative to the damage threshold, employed in the experiment.

  11. Development of an X-ray tube for irradiation experiments using a field emission electron gun

    NASA Astrophysics Data System (ADS)

    Kato, Hidetoshi; O`Rourke, Brian E.; Suzuki, Ryoichi; Wang, Jiayu; Ooi, Takashi; Nakajima, Hidetoshi

    2016-01-01

    A new X-ray tube using a ring-shaped emitter as a field emission electron source has been developed. By using a ring shaped cathode, X-rays can be extracted along the axial direction through the central hole. This cylindrically symmetrical design allows for the tube to be arranged in the axial direction with the high voltage target at one end and the X-ray beam at the other. The newly developed X-ray tube can operate at a tube voltage of more than 100 kV and at a tube current of more than 4 mA, and can be used for irradiation experiments with an irradiation dose range from mGy up to kGy. The X-ray tube can be used immediately after turning on (i.e. there is no stand-by time). In the experimental model, we demonstrated stable electron emission at a tube voltage of 100 kV and at a tube current of 4 mA during a 560 h continuous test.

  12. Characterization and identification of gamma-irradiated sauces by electron spin resonance spectroscopy using different sample pretreatments.

    PubMed

    Akram, Kashif; Ahn, Jae-Jun; Kwon, Joong-Ho

    2013-06-01

    Tomato ketchup, barbeque sauce, sweet chili sauce, and spaghetti sauce were gamma irradiated at 0, 1, 5, and 10 kGy. Electron spin resonance (ESR) technique was used to characterize the irradiated sauces, targeting radiation-induced cellulose radicals and using a modified sample pretreatment method. The samples were first washed with water, and then the residues were extracted with alcohol. The non-irradiated sauces exhibited the single central signal, whose intensity showed a significant increase on irradiation. The ESR spectra from the radiation-induced cellulose radicals, with two side peaks (g=2.02012 and g=1.98516) equally spaced (± 3 mT) from the central signal, were also observed in the irradiated sauces. The improvements in the central (natural) and radiation-induced (two side peaks corresponding to the cellulose radicals) signal intensities were obvious, when compared with routine freeze-drying and alcoholic-extraction techniques. PMID:23411320

  13. The effect of electron irradiation on the structure and iron speciation in sodium aluminum (iron) phosphate glasses

    NASA Astrophysics Data System (ADS)

    Stefanovsky, S. V.; Presniakov, I. A.; Sobolev, A. V.; Glazkova, I. S.; Kadyko, M. I.; Stefanovsky, O. I.

    2016-08-01

    The effect of 8 MeV electron irradiation on the structure of glasses in the series 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 (mol.%) and on the iron speciation in these samples was studied by FTIR and Mössbauer spectroscopic techniques. Irradiation up to a dose of 1.0 MGy has no appreciable effects on the character of the bonds within anionic motif of the glass network. Electron irradiation increases the fraction of aluminum in octahedral coordination. Iron in both unirradiated and irradiated glasses is present mainly as Fe(III) (60-75% of the total amount) in the glasses and partly as Fe(II) and the ratio of two forms remains constant up to a dose of 1.0 MGy.

  14. PALS and DSC measurements in 8 MeV electron irradiated natural rubber filled with different fillers

    NASA Astrophysics Data System (ADS)

    Mandal, Arunava; Pan, Sandip; Roychowdhury, Anirban; Sengupta, Asmita

    2015-10-01

    The effect of high energy electron irradiation on the microstructure and thermal properties of natural rubber (NR) filled with different fillers at different concentrations are studied. The samples are irradiated with 8 MeV electron beam to a total dose of 100 KGy. The change in free volume size and specific heat due to addition of fillers and irradiation are studied using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) respectively. The Positron lifetime spectra are de-convoluted into two components. The longer lived component (τo-Ps) signifies the pick-off annihilation of ortho-positronium (o-Ps) at free volume site which may be related to the radius of the free volume holes. It is observed that the specific heat (Cp) and free volume size are all affected by both irradiation and addition of fillers.

  15. Recovery of damage in rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays

    NASA Technical Reports Server (NTRS)

    Brucker, G. J.; Van Gunten, O.; Stassinopoulos, E. G.; Shapiro, P.; August, L. S.; Jordan, T. M.

    1983-01-01

    This paper reports on the recovery properties of rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays. The results indicated that complex recovery properties controlled the damage sensitivities of the tested parts. The results also indicated that damage sensitivities depended on dose rate, total dose, supply bias, gate bias, transistor type, radiation source, and particle energy. The complex nature of these dependencies make interpretation of LSI device performance in space (exposure to entire electron and proton spectra) difficult, if not impossible, without respective ground tests and analyses. Complete recovery of n-channel shifts was observed, in some cases within hours after irradiation, with equilibrium values of threshold voltages greater than their pre-irradiation values. This effect depended on total dose, radiation source, and gate bias during exposure. In contrast, the p-channel shifts recovered only 20 percent within 30 days after irradiation.

  16. Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

    1981-01-01

    The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

  17. Measurements of hot-electron temperature in laser-irradiated plasmas

    DOE PAGES

    Solodov, A. A.; Yaakobi, B.; Edgell, D. H.; Follett, R. K.; Myatt, J. F.; Sorce, C.; Froula, D. H.

    2016-10-26

    In a recently published work1–3 we reported on measuring the total energy of hot electrons produced by the interaction of a nanosecond laser with planar CH-coated molybdenum targets, using the Mo Kα emission. The temperature of the hot electrons in that work was determined by the high-energy bremsstrahlung [hard x-ray (HXR)] spectrum measured by a three-channel fluorescence-photomultiplier detector (HXRD). In the present work, we replaced the HXRD with a nine-channel image-plate (IP)–based detector (HXIP). For the same conditions (irradiance of the order of 1014 W/cm2; 2-ns pulses) the measured temperatures are consistently lower than those measured by the HXRD (bymore » a factor ~1.5 to 1.7). In addition, we supplemented this measurement with three experiments that measure the hot-electron temperature using Kα line-intensity ratios from high-Z target layers, independent of the HXR emission. These experiments yielded temperatures that were consistent with those measured by the HXIP. We showed that the thermal x-ray radiation must be included in the derivation of total energy in hot electrons (Ehot), and that this makes Ehot only weakly dependent on hot-electron temperature. For a given x-ray emission in inertial confinement fusion compression experiments, this result would lead to a higher total energy in hot electrons, but the preheat of the compressed fuel may be lower because of the reduced hot-electron range.« less

  18. Defect-mediated transport and electronic irradiation effect in individual domains of CVD-grown monolayer MoS2

    DOE PAGES

    Durand, Corentin; Zhang, Xiaoguang; Fowlkes, Jason; Najmaei, Sina; Lou, Jun; Li, An -Ping

    2015-01-16

    We study the electrical transport properties of atomically thin individual crystalline grains of MoS2 with four-probe scanning tunneling microscopy. The monolayer MoS2 domains are synthesized by chemical vapor deposition on SiO2/Si substrate. Temperature dependent measurements on conductance and mobility show that transport is dominated by an electron charge trapping and thermal release process with very low carrier density and mobility. The effects of electronic irradiation are examined by exposing the film to electron beam in the scanning electron microscope in an ultrahigh vacuum environment. The irradiation process is found to significantly affect the mobility and the carrier density of themore » material, with the conductance showing a peculiar time-dependent relaxation behavior. It is suggested that the presence of defects in active MoS2 layer and dielectric layer create charge trapping sites, and a multiple trapping and thermal release process dictates the transport and mobility characteristics. The electron beam irradiation promotes the formation of defects and impact the electrical properties of MoS2. Finally, our study reveals the important roles of defects and the electron beam irradiation effects in the electronic properties of atomic layers of MoS2.« less

  19. Laboratory Analysis Of Water, Hydrocarbon And Ammonia Ice Mixtures Exposed To High-energy Electron Irradiation

    NASA Astrophysics Data System (ADS)

    Hand, Kevin P.; Carlson, R. W.; Tsapin, A. I.

    2006-09-01

    Irradiation of low temperature ices in the laboratory provides insight into processes that may be occurring on icy bodies in the solar system. Here we report on results from high-energy (10keV) electron irradiation of thin ice films at 1e-8 torr and 70-120K. Mixtures include water with CO2, C3H8, C3H6, C4H10 (butane and isobutane), C4H8,(1-butene and cis/trans-2-butene), and NH3. During irradiation of H2O + alkane films at 80K, CO2 and CH4 production is observed and both species are retained in the ice, possibly trapped in clathrates. The -CH3 infrared bands initially present are seen to decrease with increasing dose. Bands associated with -CH2- persist, indicating polymerization of the initial short-chain hydrocarbons. In alkenes a similar evolution toward polymerization is observed, however the first step appears to be the destruction of the C=C bond. Upon warming of the film, mass spectra data compliment the mid-infrared data and indicate the production of H2CO, however glycolic acid is not explicitly seen in the mass spectra. When warmed to 300K, residues remained for all irradiated films except that of the H2O + CO2 mixtures. Residues were analyzed with Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI). Results show the production of large aliphatic, very refractory, hydrocarbons (with m/z up to 2500). Mid-infrared spectra of the residues indicate carbonyls and alcohols, likely due to polymerized aldehydes and carboxylic acids. Films of H2O + C3H8 + NH3 at 70K show the production of OCN- (cyanate ion), formamide, along with other possible amides and hydrocarbons. HPLC results indicate the production of racemic alanine. Finally, results of abiotic experiments are compared to results from the irradiation of bacterial spores in ice. The application to Europa and Enceladus is discussed.

  20. First-Principles Investigation of Electronic Excitation Dynamics in Water under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Reeves, Kyle; Kanai, Yosuke

    2015-03-01

    A predictive and quantitative understanding of electronic excitation dynamics in water under proton irradiation is of great importance in many technological areas ranging from utilizing proton beam therapy to preventing nuclear reactor damages. Despite its importance, an atomistic description of the excitation mechanism has yet to be fully understood. Identifying how a high-energy proton dissipates its kinetic energy into the electronic excitation is crucial for predicting atomistic damages, later resulting in the formation of different chemical species. In this work, we use our new, large-scale first-principles Ehrenfest dynamics method based on real-time time-dependent density functional theory to simulate the electronic response of bulk water to a fast-moving proton. In particular, we will discuss the topological nature of the electronic excitation as a function of the proton velocity. We will employ maximally-localized functions to bridge our quantitative findings from first-principles simulations to a conceptual understanding in the field of water radiolysis.

  1. Effect of electron beam irradiation on dynamic mechanical, thermal and morphological properties of LLDPE and PDMS rubber blends

    NASA Astrophysics Data System (ADS)

    Giri, Radhashyam; Naskar, Kinsuk; Nando, Golok B.

    2012-12-01

    The effect of electron beam irradiation on the blends of linear low-density polyethylene (LLDPE) and poly dimethyl siloxane rubber (PDMS) prepared over a wide range of compositions starting from 70:30 to 30:70 (LLDPE: PDMS) by varying the radiation doses from 50 to 300 kGy has been studied. The dynamic modulii and dielectric strength of the blends increase on irradiation at 100 kGy as compared to that for the unirradiated blends. Degree of crystallinity and melting behaviour remain unchanged upon irradiation upto a dose of 100 kGy, beyond which it decreases. Thermal stability increases with increase in the proportion of PDMS rubber in the blend as well as on irradiation at 100 kGy. The phase morphology of the blends examined under the SEM exhibit two phase morphology before electron beam irradiation, whereas single phase morphology is observed after electron beam irradiation due to intra- as well as inter-molecular crosslinking leading to a miscible system.

  2. Influence of electronic energy deposition on the structural modification of swift heavy-ion-irradiated amorphous germanium layers

    SciTech Connect

    Steinbach, T.; Schnohr, C. S.; Wesch, W.; Kluth, P.; Giulian, R.; Araujo, L. L.; Sprouster, D. J.; Ridgway, M. C.

    2011-02-01

    Swift heavy-ion (SHI) irradiation of amorphous germanium (a-Ge) layers leads to a strong volume expansion accompanied by a nonsaturating irreversible plastic deformation (ion hammering), which are consequences of the high local electronic energy deposition within the region of the a-Ge layer. We present a detailed study of the influence of SHI irradiation parameters on the effect of plastic deformation and structural modification. Specially prepared a-Ge layers were irradiated using two SHI energies and different angles of incidence, thus resulting in a variation of the electronic energy deposition per depth {epsilon}{sub e} between 14.0 and 38.6 keV nm{sup -1}. For all irradiation parameters used a strong swelling of the irradiated material was observed, which is caused by the formation and growth of randomly distributed voids, leading to a gradual transformation of the amorphous layer into a sponge-like porous structure as established by cross-section scanning electron microscopy investigations. The swelling depends linearly on the ion fluence and on the value of {epsilon}{sub e}, thus clearly demonstrating that the structural changes are determined solely by the electronic energy deposited within the amorphous layer. Plastic deformation shows a superlinear dependence on the ion fluence due to the simultaneous volume expansion. This influence of structural modification on plastic deformation is described by a simple approach, thus allowing estimation of the deformation yield. With these results the threshold values of the electronic energy deposition for the onset of both structural modification and plastic deformation due to SHI irradiation are determined. Furthermore, based on these results, the longstanding question concerning the reason for the structural modification observed in SHI-irradiated crystalline Ge is answered.

  3. Formation process of dislocation loops in iron under irradiations with low-energy helium, hydrogen ions or high-energy electrons

    NASA Astrophysics Data System (ADS)

    Arakawa, K.; Mori, H.; Ono, K.

    2002-12-01

    Formation processes of interstitial-type dislocation loops (I loops) in high-purity Fe under irradiations with 5 keV H + ions or 1000 keV electrons are examined by in situ transmission electron microscopy at temperatures below room temperature, and the results are compared with that obtained under He + ion irradiation. For the electron irradiation, conventional model of I-loop nucleation based on the assumption that di-interstitial atoms are stable nuclei of I loops is questioned. The volume density of I loops by H + ion irradiation is one-order of magnitude higher than that by electron irradiation, and several times lower than that by He + ion irradiation. The temperature dependence of the volume density of I loops by H + ion irradiation supports the idea that such enhancement of I-loop formation is due to trapping of self-interstitial atoms by gas atom-vacancy complexes.

  4. Optical and Electrical Studies of Gamma-Irradiated AlGaN/GaN High Electron Mobility Transistors

    NASA Astrophysics Data System (ADS)

    Yadav, Anupama; Flitsiyan, Elena; Chernyak, Leonid; Ahn, Shihyun; Ren, Fan; Pearton, Stephen; Lubomirsky, Igor; Khodorov, Sergey

    The impact of 60Co gamma-irradiation on n-channel AlGaN/GaN High Electron Mobility Transistors (HEMTs) was studied by means of temperature dependent Cathodoluminescence (CL) and Electron Beam Induced Current (EBIC) technique. Increase in diffusion length after low dose of gamma-irradiation (<= 200 Gy) is consistent with the decrease in the CL intensity. The observed effect is explained via the mechanism involving trapping of Compton electrons on irradiation induced nitrogen vacancies. For high dose (>200 Gy), diffusion length was observed to decrease which is presumably associated with the mobility degradation. It is shown that calculated activation from the EBIC and CL measurements follows exactly the same trend, which implies that same underlying phenomenon is responsible for observed findings. In addition, DC current-voltage measurements were conducted on the devices in order to relate the material's fundamental properties to the device performance.

  5. Mechanism of instability of carbides in Fe-TaC alloy under high energy electron irradiation at 673 K

    NASA Astrophysics Data System (ADS)

    Abe, Hiroaki; Ishizaki, Takahiro; Kano, Sho; Li, Feng; Satoh, Yuhki; Tanigawa, Hiroyasu; Hamaguchi, Dai; Nagase, Takeshi; Yasuda, Hidehiro

    2014-12-01

    Reduced activation ferritic/martensitic steels (RAFMs), such as F82H steel, are designed to enhance the high-temperature strength by formation of MX-type nanometer-scale precipitates, mainly TaC. However, their instability under irradiation was recently reported. The purpose of this work, therefore, is to clarify the mechanism employing simultaneous observations under electron irradiation at elevated temperature in a high voltage electron microscope. In this work, Fe-0.2 wt.% TaC was fabricated as a model alloy of F82H steel. The instability of the precipitates was observed under electron irradiation at 1 MeV or above. The remarkable shrinkage and disappearance were clearly observed under irradiation with 1.5 MeV and above. On the contrary, the precipitates were mostly stable below 0.75 MeV. Two kinds of mechanism of the irradiation-induced instability were deduced from the electron-energy dependence. One is the dissolution and diffusion of tantalum from precipitates in ferrite matrix. The other is the displacements of tantalum in precipitates that introduce dissolution of Ta into matrix.

  6. Transformation of diamond nanoparticles into onion-like carbon by electron irradiation studied directly inside an ultrahigh-vacuum transmission electron microscope

    SciTech Connect

    Hiraki, J.; Mori, H.; Taguchi, E.; Yasuda, H.; Kinoshita, H.; Ohmae, N.

    2005-05-30

    In situ observation of the transformation of diamond nanoparticles (DNP) into onion-like carbon (OLC) was made during electron-beam irradiation inside an ultrahigh-vacuum transmission electron microscope at 300 kV with 8.5x10{sup 23} e/m{sup 2}. 5 nm DNP changed into OLC within about 10 min of irradiation, while 20 nm DNP did not change to OLC but to graphite. Therefore, the size effect is critical to the formation of OLC. The mechanism of formation of OLC from DNP is discussed.

  7. A review of transmission electron microscopes with in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Hinks, J. A.

    2009-12-01

    Transmission electron microscopy (TEM) with in situ ion irradiation is unique amongst experimental techniques in allowing the direct observation of the internal microstructure of materials on the nanoscale whilst they are being subjected to bombardment with energetic particles. Invaluable insights into the underlying atomistic processes at work can be gained through direct investigation of radiation induced and enhanced effects such as: phase changes and segregation; mechanical and structural changes; atomic/layer mixing and chemical disorder; compositional changes; chemical reactions; grain growth and shrinkage; precipitation and dissolution; defect/bubble formation, growth, motion, coalescence, removal and destruction; ionisation; diffusion; and collision cascades. The experimental results obtained can be used to validate the predictions of computational models which in turn can elucidate the mechanisms behind the phenomena seen in the microscope. It is 50 years since the first TEM observations of in situ ion irradiation were made by D.W. Pashley, A.E.B. Presland and J.W. Menter at the Tube Investment Laboratories in Cambridge, United Kingdom and 40 years since the first interfacing of an ion beam system with a TEM by P.A. Thackery, R.S. Nelson and H.C. Sansom at the Atomic Energy Research Establishment at Harwell, United Kingdom. In that time the field has grown with references in the literature to around thirty examples of such facilities. This paper gives an overview of the importance of the technique, especially with regard to the current challenges faced in understanding radiation damage in nuclear environments; a description of some of the important construction elements and design considerations of TEMs with in situ ion irradiation; a brief history of the development of this type of instrument; a summary of the facilities built around the world over the last half century; and finally a focus on the instruments in operation today.

  8. Tooth Retrospective Dosimetry Using Electron Paramagnetic Resonance: Influence of Irradiated Dental Composites.

    PubMed

    Desmet, Céline M; Djurkin, Andrej; Dos Santos-Goncalvez, Ana Maria; Dong, Ruhong; Kmiec, Maciej M; Kobayashi, Kyo; Rychert, Kevin; Beun, Sébastien; Leprince, Julian G; Leloup, Gaëtane; Levêque, Philippe; Gallez, Bernard

    2015-01-01

    In the aftermath of a major radiological accident, the medical management of overexposed individuals will rely on the determination of the dose of ionizing radiations absorbed by the victims. Because people in the general population do not possess conventional dosimeters, after the fact dose reconstruction methods are needed. Free radicals are induced by radiations in the tooth enamel of victims, in direct proportion to dose, and can be quantified using Electron Paramagnetic Resonance (EPR) spectrometry, a technique that was demonstrated to be very appropriate for mass triage. The presence of dimethacrylate based restorations on teeth can interfere with the dosimetric signal from the enamel, as free radicals could also be induced in the various composites used. The aim of the present study was to screen irradiated composites for a possible radiation-induced EPR signal, to characterize it, and evaluate a possible interference with the dosimetric signal of the enamel. We investigated the most common commercial composites, and experimental compositions, for a possible class effect. The effect of the dose was studied between 10 Gy and 100 Gy using high sensitivity X-band spectrometer. The influence of this radiation-induced signal from the composite on the dosimetric signal of the enamel was also investigated using a clinical L-Band EPR spectrometer, specifically developed in the EPR center at Dartmouth College. In X-band, a radiation-induced signal was observed for high doses (25-100 Gy); it was rapidly decaying, and not detected after only 24 h post irradiation. At 10 Gy, the signal was in most cases not measurable in the commercial composites tested, with the exception of 3 composites showing a significant intensity. In L-band study, only one irradiated commercial composite influenced significantly the dosimetric signal of the tooth, with an overestimation about 30%. In conclusion, the presence of the radiation-induced signal from dental composites should not

  9. Tooth Retrospective Dosimetry Using Electron Paramagnetic Resonance: Influence of Irradiated Dental Composites

    PubMed Central

    Desmet, Céline M.; Djurkin, Andrej; Dos Santos-Goncalvez, Ana Maria; Dong, Ruhong; Kmiec, Maciej M.; Kobayashi, Kyo; Rychert, Kevin; Beun, Sébastien; Leprince, Julian G.; Leloup, Gaëtane; Levêque, Philippe; Gallez, Bernard

    2015-01-01

    In the aftermath of a major radiological accident, the medical management of overexposed individuals will rely on the determination of the dose of ionizing radiations absorbed by the victims. Because people in the general population do not possess conventional dosimeters, after the fact dose reconstruction methods are needed. Free radicals are induced by radiations in the tooth enamel of victims, in direct proportion to dose, and can be quantified using Electron Paramagnetic Resonance (EPR) spectrometry, a technique that was demonstrated to be very appropriate for mass triage. The presence of dimethacrylate based restorations on teeth can interfere with the dosimetric signal from the enamel, as free radicals could also be induced in the various composites used. The aim of the present study was to screen irradiated composites for a possible radiation-induced EPR signal, to characterize it, and evaluate a possible interference with the dosimetric signal of the enamel. We investigated the most common commercial composites, and experimental compositions, for a possible class effect. The effect of the dose was studied between 10 Gy and 100 Gy using high sensitivity X-band spectrometer. The influence of this radiation-induced signal from the composite on the dosimetric signal of the enamel was also investigated using a clinical L-Band EPR spectrometer, specifically developed in the EPR center at Dartmouth College. In X-band, a radiation-induced signal was observed for high doses (25-100 Gy); it was rapidly decaying, and not detected after only 24h post irradiation. At 10 Gy, the signal was in most cases not measurable in the commercial composites tested, with the exception of 3 composites showing a significant intensity. In L-band study, only one irradiated commercial composite influenced significantly the dosimetric signal of the tooth, with an overestimation about 30%. In conclusion, the presence of the radiation-induced signal from dental composites should not

  10. Anneal induced transforms of radiation defects in heavily electron irradiated Si diodes

    NASA Astrophysics Data System (ADS)

    Rumbauskas, V.; Meskauskaite, D.; Ceponis, T.; Gaubas, E.

    2016-09-01

    In this work, the spectra of deep traps attributed to radiation defects in n-type Czochralski (CZ) grown Si with dopant concentrations of 1015 cm-3 have been studied. Samples were irradiated with 6.6 MeV electrons with fluences in the range of (1-5) × 1016 e/cm2. Irradiated samples were annealed using isochronal 24 hour heat treatments in nitrogen (N2) gas at ambient temperature and by discretely varying the temperature from 80 °C to 280 °C. The as-irradiated and annealed samples were studied by combining capacitance-voltage (C-V), deep level transient spectroscopy (DLTS) and temperature dependent carrier trapping lifetime (TDTL) measurements. Schottky barrier contacts and ohmic contacts were deposited on the samples by Au magnetron sputtering and metal sintering, respectively, for C-V and DLTS measurements after each heat treatment procedure. In order to reduce the uncertainties due to contact quality, TDTL contact-less measurements were performed using microwave probed photoconductivity transient (MW-PC) technique. Using these techniques, we observe suppression of the rather deep carrier emission centres after heat treatment at elevated temperatures. However, the reduction of deep acceptor concentrations after anneals at elevated temperatures was observed to be accompanied by considerable increase of shallow acceptor concentrations which effectively compensate the dopants. The activation energies of the predominant peaks within the spectrum, displayed as temperature dependent carrier trapping lifetime variations, were measured and are shown to be in good agreement with those obtained from the DLTS spectra.

  11. Thermal conductivity of graphene with defects induced by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Malekpour, Hoda; Ramnani, Pankaj; Srinivasan, Srilok; Balasubramanian, Ganesh; Nika, Denis L.; Mulchandani, Ashok; Lake, Roger K.; Balandin, Alexander A.

    2016-07-01

    We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ~7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 1010 cm-2 to 1.8 × 1011 cm-2 the thermal conductivity decreases from ~(1.8 +/- 0.2) × 103 W mK-1 to ~(4.0 +/- 0.2) × 102 W mK-1 near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ~400 W mK-1. The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ~7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 1010 cm-2 to 1.8 × 1011 cm-2 the thermal conductivity decreases from ~(1.8 +/- 0.2) × 103 W mK-1 to ~(4.0 +/- 0.2) × 102 W mK-1 near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ~400 W mK-1. The thermal conductivity dependence on the defect density is

  12. Transmission Electron Microscopy Study of Graphite under in situ Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Hinks, J. A.; Jones, A. N.; Theodosiou, A.; van den Berg, J. A.; Donnelly, S. E.

    2012-07-01

    Graphite is employed as a moderator and structural component in 18 of the UK's fleet of Magnox and Advanced Gas-cooled Reactors (AGRs). During the operational lifetime of a reactor, graphite undergoes complex physical and mechanical property changes including dimensional modification, owing to the effects of temperature, oxidation and irradiation-induced atomic displacements. In order to safely extend the lifetime of the current fleet of AGRs, and also to develop materials for GenIV concepts such as the Very-High-Temperature Reactor (VHTR), it is important to gain a better understanding of the fundamental atomic processes which underpin the behaviour of graphite under current and future operational conditions. This study has focused on the effects of temperature and displacing radiation on the evolution of Mrozowski cracks in highly-orientated pyrolytic graphite (HOPG) using the new Microscope and Ion Accelerator for Materials Investigations (MIAMI) facility. This instrument allows transmission electron microscopy to be performed in situ whilst simultaneously ion irradiating to radiation damage levels typically reached in a reactor. By using this technique, it is possible to explore the development of radiation damage under a range of different conditions continuously from start-to-finish rather than just observing the end-states accessible in ex situ studies.

  13. Plasma Sprayed Metal-Ceramic Coatings and Modification of Their Structure with Pulsed Electron Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Solonenko, O. P.; Ovcharenko, V. E.; Ivanov, Yu. F.; Golovin, A. A.

    2011-06-01

    Composite powder obtained from mechanically crushed titanium carbide—metal binder cermet compacts deserves special mention for plasma spraying of wear-resistant coatings. However, cermet coatings sprayed using this powder have comparatively high porosity. The porosity causes the mechanical strength of the coating to largely deteriorate, and it also lowers the strength of the bond between the coating and the substrate. Computational and physical experiments were performed in this area to reveal the possibilities offered by pulsed electron beam irradiation for structural modification of 70 vol.%TiC-(Ni-Cr) powder coatings. The authors evaluated optimal values of process parameters for suitability in implementing a controlled thermal treatment of coatings under conditions of solid-liquid interaction of components in the cermet composition with each other and with the steel substrate. Evolution of the structure and physical properties of the cermet coatings under rapid heating and following cooling in a wide range of temperatures typical of pulsed irradiation conditions have been examined.

  14. Multi-frequency electron paramagnetic resonance study of irradiated human finger phalanxes

    NASA Astrophysics Data System (ADS)

    Zdravkova, M.; Vanhaelewyn, G.; Callens, F.; Gallez, B.; Debuyst, R.

    2005-10-01

    Electron paramagnetic resonance (EPR) is often used in dosimetry using biological samples such as teeth and bones. It is generally assumed that the radicals, formed after irradiation, are similar in both tissues as the mineral part of bone and tooth is carbonated hydroxyapatite. However, there is a lack of experimental evidence to support this assumption. The aim of the present study was to contribute to that field by studying powder and block samples of human finger phalanxes that were irradiated and analyzed by multi-frequency EPR. The results obtained from bones are different from the ones obtained in enamel by several respects: the ordering of the apatite crystallites is much smaller in bone, complicating the assignment of the observed CO 2- radicals to a specific location, and one type of CO 33- radical was only found in enamel. Moreover, a major difference was found in the non-CO 2- and non-CO 33- signals. The elucidation of the nature of these native signals (in bone and tooth enamel) still represents a big challenge.

  15. Residual, unresectable, or recurrent colorectal cancer: external beam irradiation and intraoperative electron beam boost +- resection

    SciTech Connect

    Gunderson, L.L.; Cohen, A.C.; Dosoretz, D.D.; Shipley, W.U.; Hedberg, S.E.; Wood, W.C.; Rodkey, G.V.; Suit, H.D.

    1983-11-01

    While combinations of external beam radiation (XRT) and surgery decrease pelvic recurrence and improve survival in the subgroups with residual disease (postop XRT) or initially unresectable disease (preop XRT), local recurrence is still unacceptably high, and survival could be improved. In view of this, pilot studies were instituted at Massachusetts General Hospital in which 32 patients received the standard previous treatment of external beam irradiation and surgery but in addition had an intraoperative electron beam boost of 1000 to 1500 rad to the remaining tumor or tumor bed. For the 16 patients who presented with unresectable primary lesions, the addition of intraoperative radiotherapy has resulted in a total absence of local recurrence with a minimum 20 month follow-up, and survival rates are statistically better than for the previous group treated with only external beam irradiation and surgical resection. In the group with residual disease, again there have not been any local recurrences in the 7 patients who received all treatment modalities versus 54% and 26% for the group with gross and microscopic residual treated with only external beam techniques. The remaining 9 patients presented with recurrent unresectable lesions - 3 are alive (2 NED) at greater than or equal to 3 years.

  16. Laboratory spectroscopic analyses of electron irradiated alkanes and alkenes in solar system ices

    NASA Astrophysics Data System (ADS)

    Hand, K. P.; Carlson, R. W.

    2012-03-01

    We report results from laboratory experiments of 10 keV electron irradiation of thin ice films of water and short-chain hydrocarbons at ˜10-8 Torr and temperatures ranging from 70-100 K. Hydrocarbon mixtures include water with C3H8, C3H6, C4H10 (butane and isobutane), and C4H8, (1-butene and cis/trans-2-butene). The double bonds of the alkenes in our initial mixtures were rapidly destroyed or converted to single carbon bonds, covalent bonds with hydrogen, bonds with -OH (hydroxyl), bonds with oxygen (C-O), or double bonds with oxygen (carbonyl). Spectra resulting from irradiation of alkane and alkene ices are largely indistinguishable; the initial differences in film composition are destroyed and the resulting mixture includes long-chain, branched aliphatics, aldehydes, ketones, esters, and alcohols. Methane was observed as a product during radiolysis but CO was largely absent. We find that while some of the carbon is oxidized and lost to CO2 formation, some carbon is sequestered into highly refractory, long-chain aliphatic compounds that remain as a thin residue even after the ice film has been raised to standard temperature and pressure. We conclude that the high availability of hydrogen in our experiments leads to the formation of the formyl radical which then serves as the precursor for formaldehyde and polymerization of longer hydrocarbon chains.

  17. Use of electron beam irradiation for mold decontamination on cheddar cheese.

    PubMed

    Blank, G; Shamsuzzaman, K; Sohal, S

    1992-01-01

    Cheddar cheese slices, surface-inoculated with either Penicillium cyclopium or Aspergillus ochraceus spores, were vacuum packaged and irradiated using an electron beam accelerator. Following treatment at .21 and .52 kGy, the shelf-life of cheese containing P. cyclopium was extended by 3 and 5.5 d, respectively, in comparison with inoculated, untreated samples. Under similar treatment and storage conditions, cheese containing A. ochraceus exhibited average shelf-life extensions of 42.5 and 52.2 d, respectively. Increasing the postirradiation storage temperature to 15 degrees C reduced the shelf-life of cheese, especially with samples containing A. ochraceus. The lowest dose required to inactivate ca. 50 to 60 spores/cm2 of either A. ochraceus or P. cyclopium on the surface of cheese was ca. .42 and .95 kGy, respectively. Irradiation survival curves of A. ochraceus and P. cyclopium spores in cheese yielded average values (the dose required to reduce initial population by 90%) of .21 and .42 kGy, respectively.

  18. Accelerated Partial Breast Irradiation Using Only Intraoperative Electron Radiation Therapy in Early Stage Breast Cancer

    SciTech Connect

    Maluta, Sergio; Dall'Oglio, Stefano; Marciai, Nadia; Gabbani, Milena; Franchini, Zeno; Pietrarota, Paolo; Meliado, Gabriele; Guariglia, Stefania; Cavedon, Carlo

    2012-10-01

    Background: We report the results of a single-institution, phase II trial of accelerated partial breast irradiation (APBI) using a single dose of intraoperative electron radiation therapy (IOERT) in patients with low-risk early stage breast cancer. Methods and Materials: A cohort of 226 patients with low-risk, early stage breast cancer were treated with local excision and axillary management (sentinel node biopsy with or without axillary node dissection). After the surgeon temporarily reapproximated the excision cavity, a dose of 21 Gy using IOERT was delivered to the tumor bed, with a margin of 2 cm laterally. Results: With a mean follow-up of 46 months (range, 28-63 months), only 1 case of local recurrence was reported. The observed toxicity was considered acceptable. Conclusions: APBI using a single dose of IOERT can be delivered safely in women with early, low-risk breast cancer in carefully selected patients. A longer follow-up is needed to ascertain its efficacy compared to that of the current standard treatment of whole-breast irradiation.

  19. Positron annihilation study for enhanced nitrogen-vacancy center formation in diamond by electron irradiation at 77 K

    SciTech Connect

    Tang, Z.; Chiba, T.; Nagai, Y.; Inoue, K.; Toyama, T.; Hasegawa, M.

    2014-04-28

    A compact ensemble of high density nitrogen-vacancy (NV) centers in diamond is essential to sense various external fields with a high precision at the nanoscale. Here, defects in type IIa and type Ib diamonds induced by 28 MeV electron irradiation at 77 K were studied by combining the positron annihilation spectroscopy and first-principles calculations. It is shown that the electron irradiation at 77 K can significantly enhance the NV center formation by directly converting 24% vacancies into the NV centers, indicating that it is an efficient way to produce the high density NV centers in the type Ib diamond.

  20. Study of variations in structural, optical parameters and bulk etch rate of CR-39 polymer due to electron irradiation

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Tripathy, S. P.; Joshi, D. S.; Bandyopadhyay, T.

    2016-07-01

    In this work, electron induced modifications on the bulk etch rate, structural and optical parameters of CR-39 polymer were studied using gravimetric, FTIR (Fourier Transform Infrared) and UV-vis (Ultraviolet-Visible) techniques, respectively. CR-39 samples were irradiated with 10 MeV electron beam for different durations to have the absorbed doses of 1, 10, 550, 5500, 16 500, and 55 000 kGy. From the FTIR analysis, the peak intensities at different bands were found to be changing with electron dose. A few peaks were observed to shift at high electron doses. From the UV-vis analysis, the optical band gaps for both direct and indirect transitions were found to be decreasing with the increase in electron dose whereas the opacity, number of carbon atoms in conjugation length, and the number of carbon atoms per cluster were found to be increasing. The bulk etch rate was observed to be increasing with the electron dose. The primary objective of this investigation was to study the response of CR-39 to high electron doses and to determine a suitable pre-irradiation condition. The results indicated that, the CR-39 pre-irradiated with electrons can have better sensitivity and thus can be potentially applied for neutron dosimetry.

  1. Application of backscatter electrons for large area imaging of cavities produced by neutron irradiation

    NASA Astrophysics Data System (ADS)

    Pastukhov, V. I.; Averin, S. A.; Panchenko, V. L.; Portnykh, I. A.; Freyer, P. D.; Giannuzzi, L. A.; Garner, F. A.

    2016-11-01

    It is shown that with proper optimization, backscattered electrons in a scanning electron microscope can produce images of cavity distribution in austenitic steels over a large specimen surface for a depth of ∼500-700 nm, eliminating the need for electropolishing or multiple specimen production. This technique is especially useful for quantifying cavity structures when the specimen is known or suspected to contain very heterogeneous distributions of cavities. Examples are shown for cold-worked EK-164, a very heterogeneously-swelling Russian fast reactor fuel cladding steel and also for AISI 304, a homogeneously-swelling Western steel used for major structural components of light water cooled reactors. This non-destructive overview method of quantifying cavity distribution can be used to direct the location and number of required focused ion beam prepared transmission electron microscopy specimens for examination of either neutron or ion-irradiated specimens. This technique can also be applied in stereo mode to quantify the depth dependence of cavity distributions.

  2. Study of discharge after electron irradiation in sapphires and polycrystalline alumina

    SciTech Connect

    Zarbout, K.; Moya, G.; Ahmed, A. Si; Damamme, G.; Kallel, A.

    2010-11-15

    The fraction R of charges undergoing discharge during the time separating two electron pulses is derived from the induced current method developed in a scanning electron microscope. Irradiation is performed via a 10 keV defocused electron beam and low current density. The evolution of R with temperature (in the range 300-663 K) obeys to an Arrhenius type relation. Activation energies connected with the processes involved are deduced. In sapphire, no discernible discharge is observed due to the dominance of deep traps. In silver doped sapphire, R increases sharply from 10% to 70% as the temperature rises from 360 to 420 K, with a corresponding activation energy of 0.51 eV. In contrast, in polycrystalline alumina processed by solid state sintering (grain diameters of 1.7, 2.7, and 4.5 {mu}m) the degree of discharge increases continuously with temperature and grain size. The enhancement with grain size indicates that the sintering conditions influence strongly the efficiency of a gettering effect. The activation energy below 573 K is about 0.12 eV independently of grain size. Above 573 K, a second activation energy of 0.26 eV appears for the smallest grain size sample. The results suggest that discharge may stem from a density of trapping states, associated to grain boundaries in sintered samples, rather than from a single trapping level linked to the doping element as Ag in sapphire.

  3. Increased proapoptotic activity of electron beam irradiated doxorubicin and epirubicin in multidrug-resistant human leukemic cells.

    PubMed

    Paszel-Jaworska, A; Totoń, E; Dettlaff, K; Kaczmarek, A; Bednarski, W; Oszczapowicz, I; Jelińska, A; Rybczyńska, M

    2016-10-25

    This study evaluated the effect of electron beam irradiation on the cytotoxic activity of anthracycline antibiotics such as doxorubicin (DOX), epirubicin (EPI), and dunorubicin (DAU) in human acute lymphoblastic leukemia cell line CCRF-CEM and its multidrug-resistant variant CCRF-VCR1000 cell line characterized by the overexpression of ABCB1 gene. Drugs were irradiated at doses of 10 and 25 kGy. Data from EPR studies proved that the highest concentration of free radicals was found in DOX and that the number of stable free radicals is always greater after irradiation. In in vitro studies, a higher cytotoxic activity of irradiated DOX and EPI in multidrug-resistant CCRF-VCR1000 cells was observed. This tendency was maintained during the storage at 4 °C for 90 days. Changes in CCRF-CEM cells' viability were not dependent on the irradiation status and its dose and were only drug-concentration dependent in all measurement time points. It was proved that increased potency of 25 kGy e-beam irradiated drugs results from their enhanced proapoptotic activity. Apoptotic cell death observed in CCRF-VCR1000 cells treated with irradiated drugs was caspase-8, -9, and -3 dependent and related to the increased Bax/Bcl-2 ratio. No significant differences in the effects of irradiated and non-irradiated drugs on p53 and NFκB transcription factor level and their translocation to the nucleus were noted. Increased activity of the irradiated drugs was not dependent on ABCB1 level.

  4. Metallic Li colloids studied by Li-7 MAS NMR in electron-irradiated LiF

    NASA Astrophysics Data System (ADS)

    Zogal, O. J.; Beuneu, F.; Vajda, P.; Florian, P.; Massiot, D.

    Li-7 MAS NMR spectra of 2.5 MeV electron-irradiated LiF crystals have been measured in a field of 9.4 T. Besides the resonance line of the ionic compound, a second well-separated spectrum is observed in the region of the Knight shift value for metallic lithium. At room temperature, the latter can be decomposed into two components with different Knight shift and linewidth values. When the temperature is increased, line narrowing takes place at first, indicating shortening of correlation times for self-diffusion, independently in both components. Above 370 K, both lines broaden and approach each other before collapsing into a single line. The high ppm component disappears after crossing the melting temperature of metallic lithium (454 K). The two lines are attributed to different types of metallic Li: one to bulk-like metal, the other to Li present initially under pressure and relaxing to the former under thermal treatment.

  5. Electron beam irradiation pretreatment and enzymatic saccharification of used newsprint and paper mill wastes

    NASA Astrophysics Data System (ADS)

    Waheed Khan, A.; Labrie, Jean-Pierre; McKeown, Joseph

    Electron beam pretreatment of used newsprint, pulp, as well as pulp recovered from clarifier sludge and paper mill sludge, caused the dissociation of cellulose from lignin, and rendered them suitable for enzymatic hydrolysis. A maximum dose of 1 MGy for newsprint and 1.5—2.0 MGy for pulp and paper mill sludge was required to render cellulose present in them in a form which, could be enzymatically saccharified to 90% of completion. Saccharification approaching the theoretical yield was obtained in 2 days with a cellulolytic enzyme system obtained from Trichoderma reesei. As a result of irradiation, water soluble lignin breakdown products, NaOH- soluble lignin, free cellobiose, glucose, mannose, xylose and their polymers, and acetic acid were produced from these materials.

  6. Atomistic simulation and the mechanism of graphene amorphization under electron irradiation.

    PubMed

    Liang, Zilin; Xu, Ziwei; Yan, Tianying; Ding, Feng

    2014-02-21

    Real-time reconstruction of a divacancy in graphene under electron irradiation (EI) is investigated by nonequilibrium molecular dynamic simulation (NEMD). The formation of the amorphous structure is found to be driven by the generalized Stone-Wales transformations (GSWTs), i.e. C-C bond rotations, around the defective area. The simulation reveals that each step of the reconstruction can be viewed as a quasi-thermal process and thus the reconstruction from a point defect to an amorphous structure favors the minimum energy path. On the other hand, the formation of a high energy large defective area is kinetically dominated by the balance between its expansion and shrinkage, and a kinetic model was proposed to understand the size of the defective area. The current study demonstrates that the route of the reconstruction from the point defective graphene toward an amorphous structure is predictive, though under stochastic EI.

  7. Study of free radicals in gamma irradiated cellulose of cultural heritage materials using Electron Paramagnetic Resonance

    NASA Astrophysics Data System (ADS)

    Kodama, Yasko; Rodrigues, Orlando, Jr.; Garcia, Rafael Henrique Lazzari; Santos, Paulo de Souza; Vasquez, Pablo A. S.

    2016-07-01

    Main subject of this article was to study room temperature stable radicals in Co-60 gamma irradiated contemporary paper using Electron Paramagnetic Resonance spectrometer (EPR). XRD was used to study the effect of ionizing radiation on the morphology of book paper. SEM images presented regions with cellulose fibers and regions with particles agglomeration on the cellulose fibers. Those agglomerations were rich in calcium, observed by EDS. XRD analysis confirmed presence of calcium carbonate diffraction peaks. The main objective of this study was to propose a method using conventional kinetics chemical reactions for the observed radical formed by ionizing radiation. Therefore, further analyses were made to study the half-life and the kinetics of the free radical created. This method can be suitably applied to study radicals on cultural heritage objects.

  8. Photo-recovery of electron-irradiated GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Meulenberg, Andrew

    1995-01-01

    The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, independent of the coverslide coatings, are of particular importance in terms of the predictability of GaAs solar-array lifetime in space: ( 1) The GaAs/Ge solar cells used for this series of tests displayed a much higher radiation degradation than that predicted based on JPL Solar Cell Radiation Handbook data. Covered cells degraded more in Isc than did bare cells. Short-term illumination at 60 C did not produce significant recovery (-1%) of the radiation damage. (2) However, electron radiation damage to these GaAs solar celIs anneals at 40 C when exposed to approximately 1 sun AM0 UV light sources for extended periods. The effect appears to be roughly linear with time (-1% of lsc per 1000 UVSH), is large (greater than or equal to 3%), and has not yet saturated (at 3000 hours). This photo-recovery of radiation damage to GaAs solar cells is a new effect and potentially important to the spacecraft community. The figure compares the effects of extended UV on irradiated and unirradiated GaAs solar cells with INTELSAT-6 Si cells. The effect and its generality, the extent of and conditions for photo-recovery, and the implications of such recovery for missions in radiation environments have not yet been determined.

  9. Controlled release of tyrosol and ferulic acid encapsulated in chitosan-gelatin films after electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Benbettaïeb, Nasreddine; Assifaoui, Ali; Karbowiak, Thomas; Debeaufort, Frédéric; Chambin, Odile

    2016-01-01

    This work deals with the study of the release kinetics of antioxidants (ferulic acid and tyrosol) incorporated into chitosan-gelatin edible films after irradiation processes. The aim was to determine the influence of electron beam irradiation (at 60 kGy) on the retention of antioxidants in the film, their release in water (pH=7) at 25 °C, in relation with the barrier and mechanical properties of biopolymer films. The film preparation process coupled to the irradiation induced a loss of about 20% of tyrosol but did not affect the ferulic acid content. However, 27% of the ferulic acid remained entrapped in the biopolymer network during the release experiments whereas all tyrosol was released. Irradiation induced a reduction of the release rate for both compounds, revealing that cross-linking occurred during irradiation. This was confirmed by the mechanical properties enhancement which tensile strength value significantly increased and by the reduction of permeabilities. Although molecular weights, molar volume and molecular radius of the two compounds are very similar, the effective diffusivity of tyrosol was 40 times greater than that of ferulic acid. The much lower effective diffusion coefficient of ferulic acid as determined from the release kinetics was explained by the interactions settled between ferulic acid molecules and the gelatin-chitosan matrix. As expected, the electron beam irradiation allowed modulating the retention and then the release of antioxidants encapsulated.

  10. The interaction of point defects with line dislocations in HVEM (high voltage electron microscope) irradiated Fe-Ni-Cr alloys

    SciTech Connect

    King, S.L.; Jenkins, M.L. . Dept. of Materials); Kirk, M.A. ); English, C.A. . Materials Development Div.)

    1990-05-01

    This paper presents results of a study of the interaction of point defects produced by high voltage electron microscope (HVEM) irradiation with pre-existing dislocations in austenitic Fe-15% 25%Ni-17%Cr alloys, aimed at the determination of the mechanisms of climb of dissociated dislocations. Dislocations were initially characterized at sub-threshold voltages (here 200kV) using the weak-beam technique. These dislocations were then irradiated with 1MeV electrons in the Argonne HVEM before being returned to a lower voltage microscope for post-irradiation characterization. Interstitial climb was seen only at particularly favorable sites, such as pre-existing jogs, whilst vacancies clustered near dislocations, forming stacking fault tetrahedra (SFT). Partial separations were also observed to have decreased after irradiation. The post-irradiation configuration was found to depend strongly on both dislocation character and pre-irradiation dislocation configuration. These results, and their relevance to the void swelling problem, are discussed. 52 refs., 8 figs.

  11. Monte Carlo techniques for scattering foil design and dosimetry in total skin electron irradiations.

    PubMed

    Ye, Sung-Joon; Pareek, Prem N; Spencer, Sharon; Duan, Jun; Brezovich, Ivan A

    2005-06-01

    Total skin electron irradiation (TSEI) with single fields requires large electron beams having good dose uniformity, dmax at the skin surface, and low bremsstrahlung contamination. To satisfy these requirements, energy degraders and scattering foils have to be specially designed for the given accelerator and treatment room. We used Monte Carlo (MC) techniques based on EGS4 user codes (BEAM, DOSXYZ, and DOSRZ) as a guide in the beam modifier design of our TSEI system. The dosimetric characteristics at the treatment distance of 382 cm source-to-surface distance (SSD) were verified experimentally using a linear array of 47 ion chambers, a parallel plate chamber, and radiochromic film. By matching MC simulations to standard beam measurements at 100 cm SSD, the parameters of the electron beam incident on the vacuum window were determined. Best match was achieved assuming that electrons were monoenergetic at 6.72 MeV, parallel, and distributed in a circular pattern having a Gaussian radial distribution with full width at half maximum = 0.13 cm. These parameters were then used to simulate our TSEI unit with various scattering foils. Two of the foils were fabricated and experimentally evaluated by measuring off-axis dose uniformity and depth doses. A scattering foil, consisting of a 12 x 12 cm2 aluminum plate of 0.6 cm thickness and placed at isocenter perpendicular to the beam direction, was considered optimal. It produced a beam that was flat within +/-3% up to 60 cm off-axis distance, dropped by not more than 8% at a distance of 90 cm, and had an x-ray contamination of <3%. For stationary beams, MC-computed dmax, Rp, and R50 agreed with measurements within 0.5 mm. The MC-predicted surface dose of the rotating phantom was 41% of the dose rate at dmax of the stationary phantom, whereas our calculations based on a semiempirical formula in the literature yielded a drop to 42%. The MC simulations provided the guideline of beam modifier design for TSEI and estimated the

  12. Scanning and transmission electron microscopy of the damage to small intestinal mucosa following X irradiation or hyperthermia

    SciTech Connect

    Carr, K.E.; Hume, S.P.; Marigold, J.C.; Michalowski, A.

    1982-01-01

    Scanning and transmission electron microscopy (S.E.M. and T.E.M.) and resin histology have been used to investigate the effects on mouse small intestinal villi of heating at 43 degrees C for 20 minutes and of irradiation with 10 Gy X-rays. Damage after irradiation included conical villi and giant cells. Damage after heating included the production of conical and rudimentary villi and the stacking of enterocytes. Individual cells showed signs of abnormalities in their cell membranes, nuclei and cytoplasmic components. The differences in the response after irradiation and hyperthermia are linked to the fact that heating has a primary effect on villous structure, whereas irradiation mainly affects the proliferative pool of crypt cells.

  13. Effect of 1.0 MeV electron irradiation on shunt resistance in Si-MINP solar cells

    NASA Technical Reports Server (NTRS)

    Anderson, Wayne A.; Banerjee, Sonali

    1987-01-01

    Shunt resistance from 100 K to 400 K is compared for diffused and ion implanted cells before and after irradiation. R sub sh decreases from greater than 10 to the 7th power omega-square cm for T less than 250 K to 10 to the 4th power omega-square cm at 400 K for non-irradiated diffused cells. Electron irradiation causes a more rapid decrease in R sub sh for T greater than 250 K. Ion implanted cells exhibit a similar trend except that R sub sh is significantly less for T less than 250 K and is more sensitive to irradiation at these low temperatures. The mechanism of R sub sh appears to be a combination of multistep tunneling and trapping - detrapping in the defect states of the semiconductor. Radiation serves to increase the density of these states to decrease R sub sh.

  14. X-ray spectroscopy study of electronic structure of laser-irradiated Au nanoparticles in a silica film

    SciTech Connect

    Jonnard, P.; Bercegol, H.; Lamaignere, L.; Morreeuw, J.-P.; Rullier, J.-L.; Cottancin, E.; Pellarin, M.

    2005-03-15

    The electronic structure of gold nanoparticles embedded in a silica film is studied, both before and after irradiation at 355 nm by a laser. The Au 5d occupied valence states are observed by x-ray emission spectroscopy. They show that before irradiation the gold atoms are in metallic states within the nanoparticles. After irradiation with a fluence of 0.5 J/cm{sup 2}, it is found that gold valence states are close to those of a metal-poor gold silicide; thanks to a comparison of the experimental Au 5d states with the calculated ones for gold silicides using the density-functional theory. The formation of such a compound is driven by the diffusion of the gold atoms into the silica film upon the laser irradiation. At higher fluence, 1 J/cm{sup 2}, we find a higher percentage of metallic gold that could be attributed to annealing in the silica matrix.

  15. Electron beam inactivation of Tulane virus on fresh produce, and mechanism of inactivation of human norovirus surrogates by electron beam irradiation.

    PubMed

    Predmore, Ashley; Sanglay, Gabriel C; DiCaprio, Erin; Li, Jianrong; Uribe, R M; Lee, Ken

    2015-04-01

    Ionizing radiation, whether by electron beams or gamma rays, is a non-thermal processing technique used to improve the microbial safety and shelf-life of many different food products. This technology is highly effective against bacterial pathogens, but data on its effect against foodborne viruses is limited. A mechanism of viral inactivation has been proposed with gamma irradiation, but no published study discloses a mechanism for electron beam (e-beam). This study had three distinct goals: 1) evaluate the sensitivity of a human norovirus surrogate, Tulane virus (TV), to e-beam irradiation in foods, 2) compare the difference in sensitivity of TV and murine norovirus (MNV-1) to e-beam irradiation, and 3) determine the mechanism of inactivation of these two viruses by e-beam irradiation. TV was reduced from 7 log10 units to undetectable levels at target doses of 16 kGy or higher in two food matrices (strawberries and lettuce). MNV-1 was more resistant to e-beam treatment than TV. At target doses of 4 kGy, e-beam provided a 1.6 and 1.2 log reduction of MNV-1 in phosphate buffered saline (PBS) and Dulbecco's Modified Eagle Medium (DMEM), compared to a 1.5 and 1.8 log reduction of TV in PBS and Opti-MEM, respectively. Transmission electron microscopy revealed that increased e-beam doses negatively affected the structure of both viruses. Analysis of viral proteins by SDS-PAGE found that irradiation also degraded viral proteins. Using RT-PCR, irradiation was shown to degrade viral genomic RNA. This suggests that the mechanism of inactivation of e-beam was likely the same as gamma irradiation as the damage to viral constituents led to inactivation. PMID:25590261

  16. Electron irradiation effects in YBa/sub 2/Cu/sub 3/O/sub 7-delta/ single crystals

    SciTech Connect

    Kirk, M.A.; Baker, M.C.; Liu, J.Z.; Lam, D.J.; Weber, H.W.

    1988-04-01

    Defect structures in YBa/sub 2/Cu/sub 3/O/sub 7/minus/delta/ produced by electron irradiation at 300/degree/K, were investigated by transmission electron microscopy. Threshold energies for the production of visible defects were determined to b 152 keV and 131 keV (+- 7 keV) in directions near the a- and b-axes, respectively (b > a, both perpendicular to c, the long axis in the orthorhombic structure). During above-threshold irradiations in an electron flux of 3 x 10 /sup 18/ cm/sup /minus/2/s/sup /minus/1/, extended defects were observed to form and grow to sizes of 10--50 nm over 15 minutes, in material thicknesses varying between 20 and 200 nm. Upon irradiation between the a- and b-thresholds, movement of twin plane boundaries and shrinkage of twinned volume were observed. All these findings suggest oxygen atom displacements in the basal plane with recoil energies near 20 eV. Above-threshold irradiations also show the collapse of c-axis long-range order into a planar faulted defect structure with short range order peaks at 1.2 c and 1.07 c, depending on the irradiation direction. 9 refs., 4 figs.

  17. Laws governing the creation of electronic color centers in LiF crystals acted on by pulsed irradiation

    NASA Astrophysics Data System (ADS)

    Lisitsyna, L. A.

    1996-11-01

    The processes of creating and transforming electronic color centers in an LiF crystal irradiated with a nanosecond electron pulse are investigated using pulse spectrometry with nanosecond resolution for times in the range 10-8 to 105 sec. It is shown that the thermally activated mechanism of forming Frenkel pairs in the 12 200 K range consists of successively creating exciton states, as the temperature rises, having different degrees of spatial separation of the electron and hole components. It is concluded that the structure of self-trapped excitons evolves as a function of temperature and time, and that this evolution commences for any alkali halide crystal with the creation of self-trapped excitons of D 2h point symmetry at 4 K. It is established that the interaction of electronic excitations with electronic color centers changes the properties of both the electronic excitations themselves and the color centers. In a crystal containing neutral electronic centers there is a fall in the yield of self-trapped excitons and Frenkel pairs and an increase in the contribution of the radiative channel for loss of the irradiation energy by the color centers. A mechanism is proposed for exciting luminescence of electronic color centers. It is established that short-lived irradiation-induced states exist, in particular a change in the spin state or in just the energy state of a center in the irradiation field, and that the appearance of these states changes the efficiency and directivity of the charge evolution of the electronic color centers.

  18. Indium redistribution in an InGaN quantum well induced by electron-beam irradiation in a transmission electron microscope

    SciTech Connect

    Li, T.; Hahn, E.; Gerthsen, D.; Rosenauer, A.; Strittmatter, A.; Reissmann, L.; Bimberg, D.

    2005-06-13

    The change of the morphology and indium distribution in an In{sub 0.12}Ga{sub 0.88}N quantum well embedded in GaN was investigated depending on the duration of electron-beam irradiation in a transmission electron microscope. Strain-state analysis based on high-resolution lattice-fringe images was used to determine quantitatively the local and average indium concentration of the InGaN quantum well. In-rich clusters were found already in the first image taken after 20 s of irradiation. The indium concentration in the clusters tends to increase with prolonged irradiation time. In contrast, the locally averaged indium concentration and the quantum-well width do not change within the first minute.

  19. Evolution of surface morphology and electronic structure of few layer graphene after low energy Ar{sup +} ion irradiation

    SciTech Connect

    Al-Harthi, S. H.; Kara'a, A.; Elzain, M.; Hysen, T.; Al-Hinai, A. T.; Myint, M. T. Z.

    2012-11-19

    We report on co-existing dual anisotropy ripple formation, sp bonding transformation, and variation in the delocalized {pi} electron system in 1 keV Ar{sup +} ion irradiated few-layer graphene surfaces. Ripples in directions, perpendicular and parallel to the ion beam were found. The irradiation effect and the transition from the sp{sup 2}-bonding to sp{sup 3}-hybridized state were analyzed from the deconvolution of the C (1s) peak and from the shape of the derivative of the Auger transition spectra. The results suggest a plausible mechanism for tailoring of few-layer graphene electronic band structure with interlayer coupling tuned by the ion irradiation.

  20. The effect of electron beam irradiation on properties of virgin and glass fiber-reinforced polyamide 6

    NASA Astrophysics Data System (ADS)

    Porubská, Mária; Janigová, Ivica; Jomová, Klaudia; Chodák, Ivan

    2014-09-01

    Crosslinking of virgin polyamide 6 (PA-6) and PA-6 filled with 30 wt% glass fibers (GF) was investigated. The crosslinking was initiated by electron irradiation applying dose ranging from 50 to 500 kGy. The gel point was determined to be 200 kGy for both materials. The results obtained indicate that the GF presence may retard gel formation in the PA-matrix. The irradiation of unfilled PA-6 resulted in an increase in tensile strength at break and Young's moduli (a minimum 50% gel content is needed), tensile properties at yield were not affected by crosslinking. Thermal resistance, as measured by the heat deflection temperature and Vicat softening temperature, was affected only marginally. Considering these effects, electron beam irradiation is found to be more beneficial for the virgin PA than for the corresponding PA/GF composite.

  1. Effect of electronic energy loss and irradiation temperature on color-center creation in LiF and NaCl crystals irradiated with swift heavy ions

    SciTech Connect

    Schwartz, K.; Trautmann, C.; Voss, K.-O.; Neumann, R.; Volkov, A. E.; Sorokin, M. V.; Lang, M.

    2008-07-01

    LiF and NaCl crystals were irradiated at 8 K and 300 K with various light and heavy ions (C, Ti, Ni, Kr, Sm, Au, Pb, and U) of kinetic energy between about 50 and 2600 MeV, providing electronic energy losses from 0.7 to 26.4 keV/nm. A cryostat installed at the beamline allowed in situ absorption spectroscopy and thermostimulated luminescence (TSL) measurements from 8 K upward. Creation of electron and hole color centers is analyzed as a function of irradiation temperature, fluence, and thermal and optical bleaching. Anion interstitials (I and H centers) were only observed in crystals irradiated at 8 K. These defects are unstable and disappear in the temperature range 10-100 K. For heavy ions (Au, U), the F-center accumulation efficiency at low fluences is larger at 8 K than at room temperature. The opposite effect is observed for light ions (C, Ti, Ni). The results are discussed within the frame of transient heating influencing separation or annealing of point defects.

  2. Optimal electron irradiation as a tool for functionalization of MoS{sub 2}: Theoretical and experimental investigation

    SciTech Connect

    Karmakar, Debjani Padma, N.; Ghosh, M.; Kaur, M.; Chandrasekhar Rao, T. V.; Halder, Rumu; Abraham, Geogy; Vaibhav, K.; Bhattacharya, D.

    2015-04-07

    We demonstrate the utility of electron irradiation as a tool to enhance device functionality of graphene-analogous MoS{sub 2}. With the help of first-principles based calculations, vacancy-induced changes of various electronic properties are shown to be a combined result of crystal-field modification and spin-orbital coupling. A comparative theoretical study of various possible vacancy configurations both in bulk and monolayer MoS{sub 2} and related changes in their respective band-structures help us to explain plausible irradiation induced effects. Experimentally, various structural forms of MoS{sub 2} in bulk, few layered flakes, and nanocrystals are observed to exhibit important modification of their magnetic, transport, and vibrational properties, following low doses of electron irradiation. While irradiated single crystals and nanocrystals show an enhanced magnetization, transport properties of few-layered devices show a significant increase in their conductivity, which can be very useful for fabrication of electronic devices. Our theoretical calculations reveal that this increase in n-type conductivity and magnetization can be correlated with the presence of sulfur and molybdenum vacancies.

  3. Synthesis of specific nanoparticles for targeting tumor angiogenesis using electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Deshayes, Stéphanie; Maurizot, Victor; Clochard, Marie-Claude; Berthelot, Thomas; Baudin, Cécile; Déléris, Gérard

    2010-03-01

    Angiogenesis plays a critical role in both growth and metastasis of tumors. Vascular endothelial growth factor (VEGF) is an endogenous mediator of tumor angiogenesis. Blocking associations of the VEGF with its corresponding receptors (KDR) have become critical for anti-tumor therapy. A cyclo-peptide (CBO-P11), derived from VEGF, able to inhibit the interaction between the growth factor and its receptor, was synthesized in our laboratory to provide a target for angiogenesis. We have prepared biocompatible poly(vinylidene fluoride) (PVDF) nanoparticles in order to obtain long blood circulating systems. Electron-beam (EB) irradiation was used to activate the PVDF nanoparticles. From electron paramagnetic resonance (EPR) measurements, we studied the radical stability in order to optimize the radio-grafting of acrylic acid (AA). Further functionalization of PVDF-g-PAA nanoparticles with the cyclo-peptide via a spacer arm was also possible by performing coupling reactions. High resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) and MALDI mass spectrometry allowed us to follow each chemical step of this peptide immobilization. We designed a new nanodevice suggesting a great potential for targeting angiogenesis. 7727-21-1

  4. Stability of carbon nanotubes under electron irradiation: Role of tube diameter and chirality

    SciTech Connect

    Krasheninnikov, A.V.; Banhart, F.; Li, J.X.; Foster, A.S.; Nieminen, R.M.

    2005-09-15

    As recent experiments demonstrate, the inner shells of multiwalled carbon nanotubes are more sensitive to electron irradiation than the outer shells. To understand the origin of such counterintuitive behavior, we employ a density-functional-theory based tight-binding method and calculate the displacement threshold energies for carbon atoms in single-walled nanotubes with different diameters and chiralities. We show that the displacement energy and the defect production rate strongly depend on the diameter of the nanotube and its chirality, with the displacement energy being lower, but saturating towards the value for graphite when the tube diameter increases. This implies that the threshold electron energies to produce damage in nanotubes with diameters smaller than 1 nm are less than the commonly accepted value for graphitic nanoparticles. We also calculate the displacement energies for carbon atoms near defects and show that if a single vacancy is formed, it will likely be transformed to a double vacancy, as the nanotube atomic network with double vacancies has no energetically unfavorable undercoordinated atoms.

  5. Thermal conductivity of graphene with defects induced by electron beam irradiation.

    PubMed

    Malekpour, Hoda; Ramnani, Pankaj; Srinivasan, Srilok; Balasubramanian, Ganesh; Nika, Denis L; Mulchandani, Ashok; Lake, Roger K; Balandin, Alexander A

    2016-08-14

    We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ∼7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 10(10) cm(-2) to 1.8 × 10(11) cm(-2) the thermal conductivity decreases from ∼(1.8 ± 0.2) × 10(3) W mK(-1) to ∼(4.0 ± 0.2) × 10(2) W mK(-1) near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ∼400 W mK(-1). The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management. PMID:27432290

  6. Thermal conductivity of graphene with defects induced by electron beam irradiation.

    PubMed

    Malekpour, Hoda; Ramnani, Pankaj; Srinivasan, Srilok; Balasubramanian, Ganesh; Nika, Denis L; Mulchandani, Ashok; Lake, Roger K; Balandin, Alexander A

    2016-08-14

    We investigate the thermal conductivity of suspended graphene as a function of the density of defects, ND, introduced in a controllable way. High-quality graphene layers are synthesized using chemical vapor deposition, transferred onto a transmission electron microscopy grid, and suspended over ∼7.5 μm size square holes. Defects are induced by irradiation of graphene with the low-energy electron beam (20 keV) and quantified by the Raman D-to-G peak intensity ratio. As the defect density changes from 2.0 × 10(10) cm(-2) to 1.8 × 10(11) cm(-2) the thermal conductivity decreases from ∼(1.8 ± 0.2) × 10(3) W mK(-1) to ∼(4.0 ± 0.2) × 10(2) W mK(-1) near room temperature. At higher defect densities, the thermal conductivity reveals an intriguing saturation-type behavior at a relatively high value of ∼400 W mK(-1). The thermal conductivity dependence on the defect density is analyzed using the Boltzmann transport equation and molecular dynamics simulations. The results are important for understanding phonon - point defect scattering in two-dimensional systems and for practical applications of graphene in thermal management.

  7. Preparation and characterization of keratin-based biocomposite hydrogels prepared by electron beam irradiation.

    PubMed

    Park, Mira; Kim, Byoung-Suhk; Shin, Hye Kyoung; Park, Soo-Jin; Kim, Hak-Yong

    2013-12-01

    The biocompatible and highly porous keratin-based hydrogels were prepared using electron beam irradiation (EBI). The conditions for keratin-based hydrogel formation were investigated depending on several conditions, including the presence of poly(vinyl alcohol) (PVA), concentration of keratin solution, EBI dose, and poly(ethylene imine) (PEI) additives. The pure keratin (human hair and wool) aqueous solution was not gelled by EBI, while the aqueous keratin solutions blended with PVA were gelled at an EBI dose of more than 90 kGy. Furthermore, in the presence of PEI, the aqueous keratin solution blended with PVA could be gelled at a considerably lower EBI dose, even at 10 kGy. This finding suggests that the PEI additives significantly influence the rate of gelation and that PEIs function as an accelerator during gelation. The resulting keratin-based hydrogels were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), gel fraction, degree of swelling, gel strength, and kinetics of swelling analyses.

  8. Transmission electron microscopy of the amorphization of copper indium diselenide by in situ ion irradiation

    SciTech Connect

    Hinks, J. A.; Edmondson, P. D.

    2012-03-01

    Copper indium diselenide (CIS), along with its derivatives Cu(In,Ga)(Se,S){sub 2}, is a prime candidate for use in the absorber layers of photovoltaic devices. Due to its ability to resist radiation damage, it is particularly well suited for use in extraterrestrial and other irradiating environments. However, the nature of its radiation hardness is not well understood. In this study, transmission electron microscopy (TEM) with in situ ion irradiation was used to monitor the dynamic microstructural effects of radiation damage on CIS. Samples were bombarded with 400 keV xenon ions to create large numbers of atomic displacements within the thickness of the TEM samples and thus explore the conditions under which, if any, CIS could be amorphized. By observing the impact of heavily damaging radiation in situ--rather than merely the end-state possible in ex situ experiments--at the magnifications allowed by TEM, it was possible to gain an understanding of the atomistic processes at work and the underlying mechanism that give rise to the radiation hardness of CIS. At 200 K and below, it was found that copper-poor samples could be amorphized and copper-rich samples could not. This difference in behavior is linked to the crystallographic phases that are present at different compositions. Amorphization was found to progress via a combination of one- and two-hit processes. The radiation hardness of CIS is discussed in terms of crystallographic structures/defects and the consequences these have for the ability of the material to recover from the effects of displacing radiation.

  9. Electron spin resonance detection of oxygen radicals released by UVA-irradiated human fibroblasts

    NASA Astrophysics Data System (ADS)

    Souchard, J. P.; Pierlot, G.; Barbacanne, M. A.; Charveron, M.; Bonafé, J.-L.; Nepveu, F.

    1999-01-01

    This work reports the electron spin resonance (ESR) detection of oxygenated radicals (OR) released by cultured human fibroblasts after UVA (365 nm) exposure. 5,5-dimethyl-pyrroline-N-oxide (DMPO) was used as spin trap. After a UVA irradiation of one hour, followed by a latent period of at least 45 min., and an incubation time of 30 min. in a trapping medium containing DMPO, glucose, Na^+, K+ and Ca2+ an ESR signal was recorded. By contrast, an ESR signal was produced after only 15 min. incubation when calcium ionophore A23187 was used. Although the ESR signal was characteristic of the hydroxyl adduct DMPO-OH, the use of catalase and superoxide dismutase (SOD) revealed that UVA stimulated fibroblasts released the superoxide anion O2- in the medium. SOD, vitamin C and (+)-catechin inhibited the release of superoxide generated by human fibroblasts stimulated with A23187 calcium ionophore at 5 units/ml, 10-5 M and 2× 10-4 M, respectively. Dans ce travail nous présentons la détection par résonance de spin électronique (RSE) de radicaux oxygénés (RO) libérés par des fibroblastes humains en culture après irradiation aux UVA (365 nm). Le 5,5-diméthyl-1-pyrroline-N-oxyde (DMPO) a été utilisé comme piégeur de spin. Après une irradiation aux UVA d'une heure, suivie d'une période de latence d'au moins 45 min. et d'une incubation de 30 min. dans un milieu de piégeage composé de DMPO, glucose, Na^+, K+ et Ca2+, un signal RPE est enregistré. L'ionophore calcique A23187 entraîne l'apparition d'un signal RPE après seulement 15 min. d'incubation. Bien que le signal RPE obtenu corresponde à l'adduit DMPO-OH du radical hydroxyle, l'utilisation de catalase et de superoxyde dismutase (SOD) a révélé que les fibroblastes libéraient l'anion superoxyde dans le milieu de culture. Sur ce modèle cellulaire la SOD, la vitamine C et la (+) catéchine inhibent la production du radical superoxyde aux concentrations respectivement de 5 unités/ml, 10-5 M et 2× 10-4M.

  10. Evaluation of dose variation during total skin electron irradiation using thermoluminescent dosimeters

    SciTech Connect

    Weaver, R.D.; Gerbi, B.J.; Dusenbery, K.E.

    1995-09-30

    The purpose of this study was to determine acceptable dose variation using thermoluminescent dosimeters (TLD) in the treatment of Mycosis Fungoides with total skin electron beam (TSEB) irradiation. From 1983 to 1993, 22 patients were treated with total skin electron beam therapy in the standing position. A six-field technique was used to deliver 2 Gy in two days, treating 4 days per week, to a total dose of 35 to 40 Gy using a degraded 9 MeV electron beam. Thermoluminescent dosimeters were placed on several locations of the body and the results recorded. The variations in these readings were analyzed to determine normal dose variation for various body location during TSEB. The dose to flat surfaces of the body was essentially the same as the dose to the prescription point. The dose to tangential surfaces was within {plus_minus} 10% of the prescription dose, but the readings showed much more variation (up to 24%). Thin areas of the body showed large deviations from the prescription dose along with a large amount of variation in the readings (up to 22%). Special areas of the body, such as the perineum and eyelid, showed large deviations from the prescription dose along with very large (up to 40%) variations in the readings. The TLD results of this study will be used as a quality assurance check for all new patients treated with TSEB. The results of the TLDs will be compared with this baseline study to determine if the delivered dose is within acceptable ranges. If the TLD results fall outside the acceptable limits established above, then the patient position can be modified or the technique itself evaluated. 4 refs., 5 tabs.

  11. Defect engineering in GaAs using high energy light ion irradiation: Role of electronic energy loss

    SciTech Connect

    Kabiraj, D.; Ghosh, Subhasis

    2011-02-01

    We report on the application of high energy light ions (Li and O) irradiation for modification of defects, in particular, for annihilation of point defects using electronic energy loss in GaAs to minimize the defects produced by nuclear collisions. The high resolution x-ray diffraction and micro-Raman spectroscopy have been used to monitor that no lattice damage or amorphization take place due to irradiating ions. The effects of irradiation on defects and their energy levels have been studied using thermally stimulated current spectroscopy. It has been observed that till an optimum irradiation fluence of 10{sup 13} ions/cm{sup 2} there is annihilation of native defects but further increase in irradiation fluence results in accumulation of defects, which scales with the nuclear energy loss process, indicating that the rate of defects produced by the binary collision process exceeds rate of defect annihilation. Defect annihilation due to electronic energy loss has been discussed on the basis of breaking of bonds and enhanced diffusivity of ionized native defects.

  12. Effect of high-energy electron irradiation of chicken meat on thiobarbituric acid values, shear values, odor, and cooked yield

    SciTech Connect

    Heath, J.L.; Owens, S.L.; Tesch, S.; Hannah, K.W. )

    1990-02-01

    Experiments were conducted to determine whether electron-beam irradiation would affect shear values, yield, odor, and thiobarbituric acid (TBA) values of chicken tissues. Broiler breasts (pectoralis superficialis) and whole thighs were irradiated with an electron-beam accelerator at levels to produce adsorbed doses of 100, 200, and 300 krads on the surface of the sample. The thigh samples were stored for 2, 4, and 8 days before testing for TBA values. The depth to which the radiation had penetrated the pectoralis superficialis muscle was also determined. Radiation penetrated 22 mm into slices of pectoralis superficialis muscle when 100 krad was absorbed by the surface of the tissue. The dose absorbed beneath the tissue surface to a depth of 10 mm was larger than the dose absorbed at the surface. The absorbed dose decreased as the depth of penetration increased. For cooked breast tissue, the shear values and moisture content were not affected by the absorbed radiation. Cooking losses of aged breast tissue were not affected by irradiation, but cooking losses were reduced in breast tissue that had not been aged. Irradiating uncooked thigh and uncooked breast samples produced a characteristic odor that remained after the thighs were cooked but was not detectable after the breast samples were cooked. With two exceptions, no significantly different TBA values were found that could be attributed to irradiation.

  13. Negative capacitance (impedance of the inductive type) of silicon p{sup +}-n junctions irradiated with fast electrons

    SciTech Connect

    Poklonski, N. A. Shpakovski, S. V.; Gorbachuk, N. I.; Lastovskii, S. B.

    2006-07-15

    Silicon p{sup +}-n junction diodes irradiated with 3.5-MeV electrons (with the dose of 4 x 10{sup 16} cm{sup -2}) are studied. The diodes' inductance (L) was measured at a frequency f = 1 MHz with the amplitude of alternating current equal to 0.25 mA. Simultaneously with measurements of L at alternating current, a direct current was passed through the forward-biased diode, which brought about the injection of minority charge carriers into the base. In order to identify both of the mechanisms that give rise to the inductive-type impedance in irradiated diodes with the p{sup +}-n junction and the main radiation defects that are directly involved in the formation of this impedance, irradiated samples were annealed isochronously in the temperature range T{sub a} = 225-375 deg. C with sub-sequent study of the main characteristics of the defects by deep-level transient spectroscopy. It is shown that the inductive-type impedance in irradiated diodes is caused by the processes of capture and retention of charge carriers injected into the base at the trapping centers for a time {approx}1/2f, i.e., for a half-period of oscillations. It is also shown that the trapping centers are the vacancy-oxygen complexes introduced by irradiation with electrons.

  14. Effects of gamma and electron beam irradiation on the survival of pathogens inoculated into sliced and pizza cheeses

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Joo; Ham, Jun-Sang; Lee, Ju-Woon; Kim, Keehyuk; Ha, Sang-Do; Jo, Cheorun

    2010-06-01

    The objective of this study was to identify the efficacy of gamma and electron beam irradiation of the food-borne pathogens ( Listeria monocytogenes and Staphylococcus aureus) in sliced and pizza cheeses commercially available in the Korean market. Total aerobic bacteria and yeast/mold in the cheeses ranged from 10 2 to 10 3 Log CFU/g. Irradiation of 1 kGy for sliced cheese and 3 kGy for pizza cheese were sufficient to lower the total aerobic bacteria to undetectable levels (10 1 CFU/g). Pathogen inoculation test revealed that gamma irradiation was more effective than electron beam irradiation at the same absorbed dose, and the ranges of the D 10 values were from 0.84 to 0.93 kGy for L. monocytogenes and from 0.60 to 0.63 kGy for S. aureus. Results suggest that a low dose irradiation can improve significantly the microbial quality and reduce the risk of contamination of sliced and pizza cheeses by the food-borne pathogens which can potentially occur during processing.

  15. Displacement damage analysis and modified electrical equivalent circuit for electron and photon-irradiated silicon solar cells

    NASA Astrophysics Data System (ADS)

    Arjhangmehr, Afshin; Feghhi, Seyed Amir Hossein

    2014-10-01

    Solar modules and arrays are the conventional energy resources of space satellites. Outside the earth's atmosphere, solar panels experience abnormal radiation environments and because of incident particles, photovoltaic (PV) parameters degrade. This article tries to analyze the electrical performance of electron and photon-irradiated mono-crystalline silicon (mono-Si) solar cells. PV cells are irradiated by mono-energetic electrons and poly-energetic photons and immediately characterized after the irradiation. The mean degradation of the maximum power (Pmax) of silicon solar cells is presented and correlated using the displacement damage dose (Dd) methodology. This method simplifies evaluation of cell performance in space radiation environments and produces a single characteristic curve for Pmax degradation. Furthermore, complete analysis of the results revealed that the open-circuit voltage (Voc) and the filling factor of mono-Si cells did not significantly change during the irradiation and were independent of the radiation type and fluence. Moreover, a new technique is developed that adapts the irradiation-induced effects in a single-cell equivalent electrical circuit and adjusts its elements. The "modified circuit" is capable of modeling the "radiation damage" in the electrical behavior of mono-Si solar cells and simplifies the designing of the compensation circuits.

  16. Effect of phosphorus on vacancy-type defect behaviour in electron-irradiated Ni studied by positron annihilation

    NASA Astrophysics Data System (ADS)

    Druzhkov, A. P.; Danilov, S. E.; Perminov, D. A.; Arbuzov, V. L.

    2015-02-01

    Very dilute Ni-P system (containing 50-240 appm phosphorus) irradiated by 5 MeV electrons at various temperatures (270-543 K) was studied by positron annihilation spectroscopy (PAS) and the electrical resistivity measurements. Under irradiation at 270 K (below stage III in Ni), the accumulation of the monovacancies in the Ni-P system is 1.5-2.0 times greater than that in pure Ni irradiated in the same conditions. This fact attests to the strong interaction between P atoms and self-interstitial atoms (SIAs). As a result of the non-mobile SIA-P complexes formation, the mutual recombination of point defects is suppressed and the vacancy accumulation is, respectively, enhanced. During post-irradiation annealing, the vacancy migration induces the transport process of the phosphorus atoms and leads to the formation of the vacancy clusters decorated with P atoms. The annealing behaviour of the defect structures in Ni-P systems after irradiation at enhanced temperatures was also studied. The influence of phosphorus on the formation and further evolution of the vacancy aggregates decrease with increasing of the irradiation temperature.

  17. Neutron irradiation damage of nuclear graphite studied by high-resolution transmission electron microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krishna, R.; Jones, A. N.; McDermott, L.; Marsden, B. J.

    2015-12-01

    Nuclear graphite components are produced from polycrystalline artificial graphite manufacture from a binder and filler coke with approximately 20% porosity. During the operational lifetime, nuclear graphite moderator components are subjected to fast neutron irradiation which contributes to the change of material and physical properties such as thermal expansion co-efficient, young's modulus and dimensional change. These changes are directly driven by irradiation-induced changes to the crystal structure as reflected through the bulk microstructure. It is therefore of critical importance that these irradiation changes and there implication on component property changes are fully understood. This work examines a range of irradiated graphite samples removed from the British Experimental Pile Zero (BEPO) reactor; a low temperature, low fluence, air-cooled Materials Test Reactor which operated in the UK. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) have been employed to characterise the effect of increased irradiation fluence on graphite microstructure and understand low temperature irradiation damage processes. HRTEM confirms the structural damage of the crystal lattice caused by irradiation attributed to a high number of defects generation with the accumulation of dislocation interactions at nano-scale range. Irradiation-induced crystal defects, lattice parameters and crystallite size compared to virgin nuclear graphite are characterised using selected area diffraction (SAD) patterns in TEM and Raman Spectroscopy. The consolidated 'D'peak in the Raman spectra confirms the formation of in-plane point defects and reflected as disordered regions in the lattice. The reduced intensity and broadened peaks of 'G' and 'D' in the Raman and HRTEM results confirm the appearance of turbulence and disordering of the basal planes whilst maintaining their coherent layered graphite structure.

  18. Effect of irradiation with argon ions on elastic scattering of spin-polarized electrons from W(110) surface

    NASA Astrophysics Data System (ADS)

    Dhal, Satyanarayan; Chatterjee, Shyamal; Samarin, Sergey; Williams, James F.; Giebels, Franz; Gollisch, Herbert; Feder, Roland

    2015-02-01

    The energy and azimuthal angle dependencies of the asymmetry of spin-polarized low-energy electrons ((00) beam) elastically scattered from a W(110) surface, have been studied before and after irradiated with slow Ar+ ions with energies of 200 eV, 500 eV and 1 keV at a fluence of 5 × 1015 ions/cm2. The energy dependence of the scattered electron asymmetries and intensities (for a fixed azimuthal angle of 55°, which is determined by the angle between the normal to the scattering plane and the [?] direction in the surface of the W(110) crystal) and the azimuthal angle dependence of the asymmetry for two different incident electron energies of 14 eV and 23 eV showed a significant change after irradiation. The low-energy ion irradiation influenced the spin-polarized electron scattering more than the higher energy ions. The reason for the change of spin-dependent electron scattering is a quenching of coherent elastic multiple scattering, mainly due to lattice defects induced by implanted ions. Thus, these modifications demonstrate a technological way to construct spin-active interface with required properties. The agreement between experimental results and theoretical ones with and without multiple scattering provides a consistent explanation of the observations.

  19. Probing electron density across Ar+ irradiation-induced self-organized TiO2-x nanochannels for memory application

    NASA Astrophysics Data System (ADS)

    Barman, A.; Saini, C. P.; Sarkar, P. K.; Roy, A.; Satpati, B.; Kanjilal, D.; Ghosh, S. K.; Dhar, S.; Kanjilal, A.

    2016-06-01

    The variation of electron density in TiO2-x nanochannels, exhibiting resistive switching phenomenon, produced by Ar+ ion-irradiation at the threshold fluence of 5 × 1016 ions/cm2 is demonstrated by X-ray reflectivity (XRR). The transmission electron microscopy reveals the formation of nanochannels, while the energy dispersive X-ray spectroscopy confirms Ti enrichment near the surface due to ion-irradiation, in consistent with the increase in electron density by XRR measurements. Such a variation in Ti concentration indicates the evolution of oxygen vacancies (OVs) along the TiO2-x nanochannels, and thus paves the way to explain the operation and performance of the Pt/TiO2-x/Pt-based memory devices via OV migration.

  20. Temperature and intensity dependence of the performance of an electron-irradiated (AlGa)As/GaAs solar cell

    NASA Technical Reports Server (NTRS)

    Swartz, C. K.; Hart, R. E., Jr.

    1979-01-01

    The performance of a Hughes, liquid-phase epitaxial 2 centimeter-by-2 centimeter, (AlGa)As/GaAs solar cell was measured before and after irradiations with 1 MeV electrons to fluences of 1 x 10 to the 16th power electrons/sq cm. The temperature dependence of performance was measured over the temperature range 135 to 415 K at each fluence level. In addition, temperature dependences were measured at five intensity levels from 137 to 2.57 mW/sq cm before irradiation and after a fluence of 1 x 10 to the 16th power electrons/sq cm. For the intermediate fluences, performance was measured as a function of intensity at 298 K only.

  1. Formation of Pt-Zn Alloy Nanoparticles by Electron-Beam Irradiation of Wurtzite ZnO in the TEM

    NASA Astrophysics Data System (ADS)

    Lee, Sung Bo; Park, Jucheol; van Aken, Peter A.

    2016-07-01

    As is well documented, platinum nanoparticles, promising for catalysts for fuel cells, exhibit better catalytic activities, when alloyed with Zn. Pre-existing syntheses of Pt-Zn alloy catalysts are composed of a number of complex steps. In this study, we have demonstrated that nanoparticles of Pt-Zn alloys are simply generated by electron-beam irradiation in a transmission electron microscope of a wurtzite ZnO single-crystal specimen. The initial ZnO specimen is considered to have been contaminated by Pt during specimen preparation by focused ion beam milling. The formation of the nanoparticle is explained within the framework of ionization damage (radiolysis) by electron-beam irradiation and accompanying electrostatic charging.

  2. Formation of Pt-Zn Alloy Nanoparticles by Electron-Beam Irradiation of Wurtzite ZnO in the TEM.

    PubMed

    Lee, Sung Bo; Park, Jucheol; van Aken, Peter A

    2016-12-01

    As is well documented, platinum nanoparticles, promising for catalysts for fuel cells, exhibit better catalytic activities, when alloyed with Zn. Pre-existing syntheses of Pt-Zn alloy catalysts are composed of a number of complex steps. In this study, we have demonstrated that nanoparticles of Pt-Zn alloys are simply generated by electron-beam irradiation in a transmission electron microscope of a wurtzite ZnO single-crystal specimen. The initial ZnO specimen is considered to have been contaminated by Pt during specimen preparation by focused ion beam milling. The formation of the nanoparticle is explained within the framework of ionization damage (radiolysis) by electron-beam irradiation and accompanying electrostatic charging. PMID:27440080

  3. Combined effects of nuclear and electronic energy losses in solids irradiated with a dual-ion beam

    NASA Astrophysics Data System (ADS)

    Thomé, Lionel; Debelle, Aurélien; Garrido, Frédérico; Trocellier, Patrick; Serruys, Yves; Velisa, Gihan; Miro, Sandrine

    2013-04-01

    Single and dual-beam irradiations of oxide (c-ZrO2, MgO, Gd2Ti2O7) and carbide (SiC) single crystals were performed to study combined effects of nuclear (Sn) and electronic (Se) energy losses. Rutherford backscattering experiments in channeling conditions show that the Sn/Se cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO2 and Gd2Ti2O7. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative Sn/Se effects may lead to the preservation of the integrity of nuclear devices.

  4. Controlling Edge Morphology in Graphene Layers Using Electron Irradiation: From Sharp Atomic Edges to Coalesced Layers Forming Loops

    SciTech Connect

    Cruz-Silva, E.; Botello-Mendez, A.R.; Barnett, Zachary M; Jia, Xiaoting; Dresselhaus, M; Terrones, H.; Terrones, M.; Sumpter, Bobby G; Meunier, Vincent

    2010-01-01

    Recent experimental reports indicate that Joule heating can atomically sharpen the edges of chemical vapor deposition grown graphitic nanoribbons. The absence or presence of loops between adjacent layers in the annealed materials is the topic of a growing debate that this Letter aims to put to rest. We offer a rationale explaining why loops do form if Joule heating is used alone, and why adjacent nanoribbon layers do not coalesce when Joule heating is applied after high-energy electrons first irradiate the sample. Our work, based on large-scale quantum molecular dynamics and electronic-transport calculations, shows that vacancies on adjacent graphene sheets, created by electron irradiation, inhibit the formation of edge loops.

  5. Thermal response of double-layered metal films after ultrashort pulsed laser irradiation: The role of nonthermal electron dynamics

    SciTech Connect

    Tsibidis, George D.

    2014-02-03

    The thermal response of a Cu-Ti double-layered film is investigated after laser irradiation with ultrashort pulses (pulse duration τ{sub p} = 50 fs, 800 nm laser wavelength) in submelting conditions by including the influence of nonthermal electrons. A revised two-temperature model is employed to account for the contribution of nonthermal electron distribution while the variation of the optical properties of the material during the laser beam irradiation is also incorporated into the model. Theoretical results can provide significant insight into the physical mechanism that characterize electron dynamics and can facilitate production of controllable ultra-high strength Cu-Ti alloys with promising applications.

  6. Effectiveness of trimethylopropane trimethacrylate for the electron-beam-irradiation-induced cross-linking of polylactic acid

    NASA Astrophysics Data System (ADS)

    Ng, Hon-Meng; Bee, Soo-Tueen; Ratnam, C. T.; Sin, Lee Tin; Phang, Yee-Yao; Tee, Tiam-Ting; Rahmat, A. R.

    2014-01-01

    The purpose of this research was to investigate the effects of various loading levels of trimethylopropane trimethacrylate (TMPTMA) on the properties of polylactic acid (PLA) cross-linked via electron-beam irradiation. PLA was compounded with 3-5 wt.% of TMPTMA to induce cross-linking upon subjection to electron-beam irradiation doses of 25-250 kGy. The physical properties of the PLA samples were characterised by means of X-ray diffraction, gel fraction and scanning electron microscopy analyses on fractured surfaces after tensile tests. The presence of TMPTMA in PLA was found to effectively increase the crystallite size and gel fraction. However, higher loading levels of TMPTMA could compromise the properties of the PLA/TMPTMA samples, indicating that a larger amount of monomer free radicals might promote degradation within the substantially cross-linked amorphous phase. Irradiation-induced cross-linking in the samples could improve the cross-linking density while decreasing the elongation and interfering with the crystallisation. These effects are caused by the intensive irradiation-induced chain scission that is responsible for the deterioration of the mechanical and crystalline properties of the samples.

  7. Effects of electronic and nuclear stopping power on disorder induced in GaN under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Moisy, F.; Sall, M.; Grygiel, C.; Balanzat, E.; Boisserie, M.; Lacroix, B.; Simon, P.; Monnet, I.

    2016-08-01

    Wurtzite GaN epilayers, grown on the c-plane of sapphire substrate, have been irradiated with swift heavy ions at different energies and fluences, and thereafter studied by Raman scattering spectroscopy, UV-visible spectroscopy and transmission electron microscopy. Raman spectra show strong structural modifications in the GaN layer. Indeed, in addition to the broadening of the allowed modes, a large continuum and three new modes at approximately 200 cm-1, 300 cm-1 and 670 cm-1 appear after irradiation attributed to disorder-activated Raman scattering. In this case, spectra are driven by the phonon density of states of the material due to the loss of translation symmetry of the lattice induced by defects. It was shown qualitatively that both electronic excitations and elastic collisions play an important role in the disorder induced by irradiation. UV-visible spectra reveal an absorption band at 2.8 eV which is linked to the new mode at 300 cm-1 observed in irradiated Raman spectra and comes from Ga-vacancies. These color centers are produced by elastic collisions (without any visible effect of electronic excitations).

  8. Defects and annealing studies in 1-Me electron irradiated (AlGa)As-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.; Wang, W. L.; Loo, R. Y.; Rahilly, W. P.

    1982-01-01

    The deep-level defects and recombination mechanisms in the one-MeV electron irradiated (AlGa)As-GaAs solar cells under various irradiation and annealing conditions are discussed. Deep-level transient spectroscopy (DLTS) and capacitance-voltage (CV) techniques were used to determine the defect and recombination parameters such as energy levels and defect density, carrier capture cross sections and lifetimes for both electron and hole traps as well as hole diffusion lengths in these electron irradiated GaAs solar cells. GaAs solar cells used in this study were prepared by the infinite solution melt liquid phase epitaxial (LPE) technique at Hughes Research Lab., with (Al0.9Ga0.1)-As window layer, Be-diffused p-GaAs layer on Sn-doped n-GaAs or undoped n-GaAs active layer grown on n(+)-GaAs substrate. Mesa structure with area of 5.86x1000 sq cm was fabricated. Three different irradiation and annealing experiments were performed on these solar cells.

  9. NOTE: Intraoperative radiation therapy using a mobile electron linear accelerator: field matching for large-field electron irradiation

    NASA Astrophysics Data System (ADS)

    Beddar, A. S.; Briere, T. M.; Ouzidane, M.

    2006-09-01

    Intraoperative radiation therapy (IORT) consists of delivering a large, single-fraction dose of radiation to a surgically exposed tumour or tumour bed at the time of surgery. With the availability of a mobile linear accelerator in the OR, IORT procedures have become more feasible for medical centres and more accessible to cancer patients. Often the area requiring irradiation is larger than what the treatment applicators will allow, and therefore, two or more adjoining fields are used. Unfortunately, the divergence and scattering of the electron beams may cause significant dose variations in the region of the field junction. Furthermore, because IORT treatments are delivered in a large single fraction, the effects of underdosing or overdosing could be more critical when compared to fractionated external beam therapy. Proper matching of the fields is therefore an important technical aspect of treatment delivery. We have studied the matching region using the largest flat applicator available for three different possibilities: abutting the fields, leaving a small gap or creating an overlap. Measurements were done using film dosimetry for the available energies of 4, 6, 9 and 12 MeV. Our results show the presence of clinically significant cold spots for the low-energy beams when the fields are either gapped or abutted, suggesting that the fields should be overlapped. No fields should be gapped. The results suggest that an optimal dose distribution may be obtained by overlapping the fields at 4 and 6 MeV and simply abutting the fields at 9 and 12 MeV. However, due to uncertainties in the placement of lead shields during treatment delivery, one may wish to consider overlapping the higher energy fields as well.

  10. Electron-irradiation induced changes in the phases and photocatalytic activity of TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Sapnar, K. B.; Dhole, S. D.; Bhoraskar, V. N.

    2012-04-01

    Samples of TiO2 nanoparticles, with mixed anatase and rutile phases, were irradiated with 6.5 MeV electrons at fluences, 1.5, 2.0, 2.5, 3.0, and 3.5 × 1015 e cm-2 and characterized by several methods. With increasing electron fluence, a continuous decrease in the average particle size from ˜80 nm to around 30 nm were observed along with a decrease in the rutile and the anatase phases of TiO2, but at different rates, and growth of the TiO2 brookite phase at slow rate. The photocatalytic activities of different electron irradiated TiO2 samples, in the photodegradation of methylene blue, were studied by recording UV-Vis absorption spectra of the respective solutions. On electron irradiation, even though the rutile phase in the TiO2 was decreasing, the photocatalytic activity of the nanoparticles increased continuously with fluence up to ˜3.0 × 1015 e cm-2, but decreased at 3.5 × 1015 e cm-2. The energy levels introduced by the brookite phase and the electron induced defects in TiO2 could have effectively reduced the electron-hole recombination rate in the absence of the rutile phase. The observed enhancement in the photocatalytic activity of the irradiated TiO2 is attributed to the formation of small size particles, the introduction of the oxygen related vacancies and other defects, the growth of the brookite phase, and increased absorption of radiation over the ultraviolet and visible range.

  11. Fast electron generation and transport in solid matter irradiated at relativistic intensities. Evidence of vxB acceleration

    NASA Astrophysics Data System (ADS)

    Baton, S. D.; Santos, J. J.; Amiranoff, F.; Popescu, H.; Gremillet, L.; Koenig, M.; Martinolli, E.; Rousseaux, C.; Rabec-Le-Gloahec, M.; Hall, T. A.; Batani, D.; Perelli, E.; Scianitti, F.; Cowan, T. E.

    2002-11-01

    In the context of the fast electron transport in solid matter and the fast ignitor scheme,we report on measurements of second harmonic of the laser light observed on the rear side of solid targets irradiated by the 100 TW laser at LULI. This emission can be explained by the acceleration of short bunches of electrons in the front of the target by the vxB force. The observations indicate that, in our conditions, the minimum fraction of the laser energy transferred to these electron bunches is of the order of 1 °.

  12. Involvement of cyclic electron flow in irradiance stress responding and its potential regulation of the mechanisms in Pyropia yezoensis

    NASA Astrophysics Data System (ADS)

    Niu, Jianfeng; Feng, Jianhua; Xie, Xiujun; Gao, Shan; Wang, Guangce

    2016-07-01

    Pyropia yezoensis, belongs to the genus of Porphyra before 2011, inhabit on intertidal zone rocks where irradiation changes dramatically, implying that the seaweed has gained certain mechanisms to survive a harsh environment. Based on the photosynthetic parameters with or without the inhibitors determined by a Dual-PAM-100 apparatus, we investigated the photosynthetic performance and the changes in electron flow that occurred during the algae were stressed with different light intensities previously. When the irradiation saturation was approaching, the CEF around PS I became crucial since the addition of inhibitors usually led to an increase in non-photochemical quenching. The inhibitor experiments showed that there were at least three different CEF pathways in Py. yezoensis and these pathways compensated each other. In addition to maintaining a proper ratio of ATP/NAD(P)H to support efficient photosynthesis, the potential roles of CEF might also include the regulation of different photoprotective mechanisms in Py. yezoensis. Under the regulation of CEF, chlororespiration is thought to transport electrons from the reduced plastoquinone (PQ) pool to oxygen in order to mitigate the reduction in the electron transfer chain. When irradiation was up to the high-grade stress conditions, the relative value of CEF began to decrease, which implied that the NADP+ pool or PQ+ pool was very small and that the electrons were transferred from reduced PS I to oxygen. The scavenging enzymes might be activated and the water-water cycle probably became an effective means of removing the active oxygen produced by the irradiation stressed Py. yezoensis. We believe that the different mechanisms could make up the photoprotective network to allow Py. yezoensis for survival in a highly variable light stress habitat, which may enlighten scientists in future studies on irradiance stress in other algae species.

  13. Microwave irradiation for shortening the processing time of samples of flagellated bacteria for scanning electron microscopy.

    PubMed

    Hernández-Chavarría, Francisco

    2004-01-01

    Microwave irradiation (MWI) has been applied to the development of rapid methods to process biological samples for scanning electron microscopy (SEM). In this paper we propose two simple and quick techniques for processing bacteria (Proteus mirabilis and Vibrio mimicus) for SEM using MWI. In the simplest methodology, the bacteria were placed on a cover-glass, air-dried, and submitted to conductivity stain. The reagent used for the conductivity stain was the mordant of a light microscopy staining method (10 ml of 5% carbolic acid solution, 2 g of tannic acid, and 10 ml of saturated aluminum sulfate 12-H2O). In the second method the samples were double fixed (glutaraldehyde and then osmium), submitted to conductivity stain, dehydrated through a series of ethanol solutions of increasing concentration, treated with hexamethyldisilazine (HMDS), and dried at 35 degrees C for 5 minutes. In both methods the steps from fixation to treatment with HMDS were done under MWI for 2 minutes in an ice-water bath, in order to dissipate the heat generated by the MWI. Although both techniques preserve bacterial morphology adequately, the latter, technique showed the best preservation, including the appearance of flagella, and that process was completed in less than 2 hours at temperatures of MWI between 4 to 5 degrees C. PMID:17061527

  14. ACPSEM ROSG TBE working group recommendations for quality assurance in total body electron irradiation.

    PubMed

    Nelligan, Raelene; Baldwin, Zoë; Ostwald, Trish; Tran, Thu; Bailey, Michael

    2015-09-01

    The Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) Radiation Oncology Specialty Group (ROSG) formed a series of working groups in 2011 to develop recommendations for guidance of radiation oncology medical physics practice within the Australasian setting. These recommendations are intended to provide guidance for safe work practices and a suitable level of quality control without detailed work instructions. It is the responsibility of the medical physicist to ensure that locally available equipment and procedures are sufficiently sensitive to establish compliance to these recommendations. The recommendations are endorsed by the ROSG, and have been subject to independent expert reviews. For the Australian readers, these recommendations should be read in conjunction with the Tripartite Radiation Oncology Reform Implementation Committee Quality Working Group: Radiation Oncology Practice Standards (2011), and Radiation Oncology Practice Standards Supplementary Guide (2011). This publication presents the recommendations of the ACPSEM ROSG Total Body Electron Irradiation Working Group and has been developed in alignment with other international associations. However, these recommendations should be read in conjunction with relevant national, state or territory legislation and local requirements, which take precedence over the ACPSEM recommendations. It is hoped that the users of this and other ACPSEM recommendations will contribute to the development of future versions through the Radiation Oncology Specialty Group of the ACPSEM. This document serves as a guideline for calibration and quality assurance of equipment used for TBE in Australasia.

  15. Xe precipitates at grain boundaries in Al under 1 MeV electron irradiation.

    SciTech Connect

    Allen, C. W.

    1998-10-23

    Crystalline nanoprecipitates of Xe have been produced by ion implantation into mazed bicrystalline Al at 300 K, in which the matrix grain boundaries are mainly 90 deg tilt boundaries. Within Al grains, Xe nanocrystals are fee, isotactic with the Al and cuboctohedral in shape with {l_brace}111{r_brace} and {l_brace}100{r_brace} facets. With an off-axial imaging technique, the nanocrystals were structure imaged against a relatively featureless matrix background. In contrast to metal precipitates in Al, such as Pb, Xe precipitates straddling a matrix grain boundary are bicrystals as small as approximately 2 nm in diameter. Larger Xe precipitates tend to avoid boundaries which are inclined away from asymmetrical orientation and which thus have a significant twist component. Under the 1 MeV electron irradiation employed for HREM observation, small Xe nanocrystals near a grain boundary may migrate to the boundary and coalesce with other Xe precipitates. The structural observations are rationalized on a simple geometrical interpretation.

  16. The formation mechanism of multiple vacancies and amorphous graphene under electron irradiation.

    PubMed

    Zhao, Ruiqi; Zhuang, Jianing; Liang, Zilin; Yan, Tianying; Ding, Feng

    2015-05-14

    The evolution of multiple vacancies (Vns) in graphene under electron irradiation (EI) was explored systematically by long time non-equilibrium molecular dynamics simulations, with n varying from 4 to 40. The simulations showed that the Vns form haeckelites in the case with small n, while forming holes as n increases. The scale of the haeckelites, characterized by the number of pentagon-heptagon pairs, grows linearly with n. Such a linear relationship can be interpreted as a consequence of compensating the missing area, caused by the Vns, in order to maintain the area of the perfect sp(2) network by self-healing. Beyond that, the scale of the haeckelite vs. the density of missing atoms is predicted to be Sh ∼ 6Dn, where Sh and Dn are the percentage of non-hexagonal rings and missing atoms, respectively. This study provides an intuitive picture of the formation of amorphous graphene under EI and the quantitative understanding of the mechanism. PMID:25886665

  17. Reversible wettability of electron-beam deposited indium-tin-oxide driven by ns-UV irradiation

    SciTech Connect

    Persano, Luana; Del Carro, Pompilio; Pisignano, Dario

    2012-04-09

    Indium tin oxide (ITO) is one of the most widely used semiconductor oxides in the field of organic optoelectronics, especially for the realization of anode contacts. Here the authors report on the control of the wettability properties of ITO films deposited by reactive electron beam deposition and irradiated by means of nanosecond-pulsed UV irradiation. The enhancement of the surface water wettability, with a reduction of the water contact angle larger than 50 deg., is achieved by few tens of seconds of irradiation. The analyzed photo-induced wettability change is fully reversible in agreement with a surface-defect model, and it can be exploited to realize optically transparent, conductive surfaces with controllable wetting properties for sensors and microfluidic circuits.

  18. Irradiation Effects in Fosterrite and the Nature of Interstellar Grains: A Coordinated Spectroscopy and Electron Microscopy Study

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Christoffersen, R.

    2007-01-01

    Crystalline and amorphous silicates condense in the outflows of low mass evolved stars and massive red supergiant stars and are injected into the interstellar medium (ISM) where they are rendered almost completely amorphous by a multitude of destructive processes (e.g. shock, grain-grain collisions, and irradiation). Irradiation effects in particular may have played an important role in the genesis and modification of primitive grains in cometary dust, but unraveling those effects requires controlled experiments under appropriate conditions and with an emphasis on materials relevant to the ISM. Here we report our infrared (IR) microspectroscopy and trans-mission electron microscope (TEM) measurements on forsterite that was amorphized through irradiation by high energy heavy ions.

  19. Formation of oxidizing species via irradiation of perchlorates using high-energy electrons and D 2 + ions

    NASA Astrophysics Data System (ADS)

    Crandall, Parker B.; Gillis-Davis, Jeffrey J.; Kaiser, Ralf-Ingo

    2016-10-01

    The perchlorate ion (ClO4–) has garnered particular interest in recent years following the discovery of perchlorate salts in the Martian regolith at levels of 0.4–0.6 wt% by the Phoenix lander in 2006 and Mars Science Laboratory's Curiosity rover in 2013. Due to their oxidizing properties, perchlorates are suspected to play a contributing role to the surprising lack of organics on the Martian surface. In this study, magnesium perchlorate hexahydrate (Mg(ClO4)2●6H2O) samples were irradiated with monoenergetic beams of 5 keV electrons and D2+ ions separately, sequentially, and simultaneously to simulate the effects of galactic cosmic ray exposure of perchlorates. The irradiation experiments were carried out under ultra-high vacuum conditions at 50 K, after which the samples were slowly heated to 300 K (0.5 K min–1) while desorbing products were monitored by quadrupole mass spectrometry. In all cases, molecular oxygen (O2) was detected upon the onset of irradiation and again during the warmup phase. In the case of simultaneous irradiation, deuterated water (D2O) and deuterium peroxide (D2O2) were also detected as the sample was heated whereas in the D2+ experiment small amounts of D2O2 was found exclusively. When samples were irradiated sequentially, the production of D2O2 was dependent upon the sample being irradiated with D2+ ions prior to electrons. These experiments show that perchlorates are capable of producing multiple oxidizing agents (O2, D2O2) which may also account for the lack of organics on the Martian surface.

  20. Effect of electron beam irradiation on bacterial and Ascaris ova loads and volatile organic compounds in municipal sewage sludge

    NASA Astrophysics Data System (ADS)

    Engohang-Ndong, Jean; Uribe, R. M.; Gregory, Roger; Gangoda, Mahinda; Nickelsen, Mike G.; Loar, Philip

    2015-07-01

    Wastewater treatment plants produce large amounts of biosolids that can be utilized for land applications. However, prior to their use, these biosolids must be treated to eliminate risks of infections and to reduce upsetting odors. In this study, microbiological and chemical analyzes were performed before and after treatment of sewage sludge with 3 MeV of an electron beam accelerator in a pilot processing plant. Thus, we determined that dose 4.5 kGy was required to reduce fecal coliform counts to safe levels for land applications of sludge while, 14.5 kGy was necessary to decrease Ascaris ova counts to safe levels. Furthermore, at low doses, electron beam irradiation showed little effect on the concentrations of volatile organic compounds, while some increase were recorded at high doses. The concentration of dimethyl sulfide was reduced by 50-70% at irradiation doses of 25.7 kGy and 30.7 kGy respectively. By contrast, electron beam irradiation increased dimethyl disulfide concentrations. We also showed that electron beam treatment was less energy-consuming with shorter processing times than conventional techniques used to decontaminate sludge. Hence opening new avenues for large urban agglomerations to save money and time when treating biosolids for land application.

  1. Annealing and anomalous high-energy electron irradiation effects in low-cost silicon N+P solar cells

    NASA Technical Reports Server (NTRS)

    Garlick, G. F. J.; Kachare, A. H.

    1981-01-01

    Silicon solar cells of N(+)P type were subjected to 1 MeV electron irradiation (up to 10 to the 16th electrons/sq cm) and then annealed at 450 C for 20 min or annealed with no electron irradiation. Electron irradiation resulted in a degradation of longer wavelength cell response, but produced a marked enhancement of response at shorter wavelengths with a peak change of 40% at 0.44 microns. Subsequent thermal anneal at 450 C reduced the long-wavelength degradation, but enhancement at shorter wavelengths persisted. Excitation at the shorter wavelengths was in the N(+)-diffused layer and in the junction region of the cell. Anneal of unirradiated cells produced shorter-wavelength enhancement with a similar peaking at 0.44 microns, but with a relative change of only 20%. More enhancement was produced in the longer wavelength region (up to 0.8 microns). These effects in the different cell regions are explained by a decrease in the interstitial oxygen-impurity complexes (deep recombination levels) and the formation of substantial oxygen-silicon vacancy centers (donors).

  2. Advanced electron microscopic techniques applied to the characterization of irradiation effects and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment

    SciTech Connect

    Rooyen, I.J. van; Lillo, T.M.; Trowbridge, T.L.; Madden, J.M.; Wu, Y.Q.; Goran, D.

    2013-07-01

    Preliminary electron microscopy of coated fuel particles from the AGR-1 experiment was conducted using characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). Microscopic quantification of fission-product precipitates was performed. Although numerous micro- and nano-sized precipitates observed in the coating layers during initial SEM characterization of the cross-sections, and in subsequent TEM diffraction patterns, were indexed as UPd{sub 2}Si{sub 2}, no Ag was conclusively found. Additionally, characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates in the presence of significantly higher concentrations of Pd and U. The electron microscopy team followed a multi-directional and phased approach in the identification of fission products in irradiated TRISO fuel. The advanced electron microscopy techniques discussed in this paper, not only demonstrate the usefulness of the equipment (methods) as relevant research tools, but also provide relevant scientific results which increase the knowledge about TRISO fuel particles microstructure and fission products transport.

  3. Evidence for weakly bound electrons in non-irradiated alkane crystals: The electrons as a probe of structural differences in crystals

    SciTech Connect

    Pietrow, M. Misiak, L. E.; Gagoś, M.; Kornarzyński, K.; Szurkowski, J.; Grzegorczyk, M.; Rochowski, P.

    2015-02-14

    It is generally assumed that weakly bound (trapped) electrons in organic solids come only from radiolytical (or photochemical) processes like ionization caused by an excited positron entering the sample. This paper presents evidence for the presence of these electrons in non-irradiated samples of docosane. This can be due to the triboelectrification process. We argue that these electrons can be located (trapped) either in interlamellar gaps or in spaces made by non-planar conformers. Electrons from the former ones are bound more weakly than electrons from the latter ones. The origin of Vis absorption for the samples is explained. These spectra can be used as a probe indicating differences in the solid structures of hydrocarbons.

  4. Evidence for weakly bound electrons in non-irradiated alkane crystals: The electrons as a probe of structural differences in crystals.

    PubMed

    Pietrow, M; Gagoś, M; Misiak, L E; Kornarzyński, K; Szurkowski, J; Rochowski, P; Grzegorczyk, M

    2015-02-14

    It is generally assumed that weakly bound (trapped) electrons in organic solids come only from radiolytical (or photochemical) processes like ionization caused by an excited positron entering the sample. This paper presents evidence for the presence of these electrons in non-irradiated samples of docosane. This can be due to the triboelectrification process. We argue that these electrons can be located (trapped) either in interlamellar gaps or in spaces made by non-planar conformers. Electrons from the former ones are bound more weakly than electrons from the latter ones. The origin of Vis absorption for the samples is explained. These spectra can be used as a probe indicating differences in the solid structures of hydrocarbons.

  5. The effect of electron beam irradiation on forensic evidence. 1. Latent print recovery on porous and non-porous surfaces.

    PubMed

    Ramotowski, Robert S; Regen, Erin M

    2005-03-01

    The recent use of the postal system as a means of delivering anthrax spores via several contaminated envelopes has led to the selective irradiation of mail. These as yet unsolved attacks and the U.S. Postal Service's decision to irradiate certain types of mail has led to some unexpected complications. The high doses of radiation required to destroy biological agents like anthrax are sufficient to induce damage to other materials present in the envelope. There have been reports of damage to many different items that have been subjected to irradiation, including paper, precious gems, plastic, computer discs, and electronics. However, few studies have examined the effect of such treatments on items of forensic interest. In this paper, the authors focused on the impact of the irradiation process on the ability to visualize latent prints. This experiment involved using several donors, substrates (both porous and non-porous), and visualization reagents. The results indicate that the irradiation process can have a detrimental effect on the success of certain visualization reagents.

  6. Low energy electron beam irradiation effect on optical properties of nanopillar MQW InGaN/GaN structures

    SciTech Connect

    Yakimov, E. B.; Vergeles, P. S.; Polyakov, A. Y.; Jeon, Dae-Woo; Lee, In-Hwan

    2014-02-21

    The low energy electron beam irradiation (LEEBI) effect on optical properties of planar and nanopillar InGaN/GaN muliple quantum well light emitting structures was studied by the cathodoluminescence (CL) method. On the planar structures LEEBI leads to a formation of new InGaN-related emission bands red shifted in comparison with initial one at small irradiation doses and blue shifted at doses higher than 0.5 C/cm{sup 2}. It was observed that after dry etching used for the nanopillar formation the main InGaN-related emission line moves from 2.92 to 2.98 eV that can be explained by a strain relaxation in the quantum wells. The optical properties of nanopilars start to change under LEEBI at a dose of about one order of magnitude lower than that for planar structures. At high irradiation doses the behavior of both structures under LEEBI is similar. The results obtained were explained by the formation and reconstruction of quantum dots inside the quantum wells due to a point defect generation and redistribution stimulated by the electron beam irradiation.

  7. 1 MeV electron irradiation of solid Xe nanoclusters in Al : an in-situ HRTEM study.

    SciTech Connect

    Donnelly, S. E.; Furuya, K.; Song, M.; Birtcher, R. C.; Allen, C. W.

    1997-12-05

    Thin film samples of a simple embedded nanocluster system consisting of solid Xe precipitates in Al have been subjected to 1 MeV electron irradiation in a high-voltage electron microscope. High-resolution images have been recorded on videotape in order to monitor the changes to the system resulting from the passage of electrons through the film. Inspection of the video recordings (in some cases frame-by-frame) reveals that complex, rapid processes occur under the electron beam. These include, movement of small clusters, coalescence of neighboring clusters, shape changes, the apparent melting and resolidification of the Xe, and the creation and annealing of extended defects within the Xe lattice. A tentative interpretation of some of the observations is presented in terms of the electron-induced displacement processes at the surface of the clusters.

  8. Thorium silicate compound as a solid-state target for production of isomeric thorium-229 nuclei by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Borisyuk, P. V.; Vasilyev, O. S.; Lebedinskii, Y. Y.; Krasavin, A. V.; Tkalya, E. V.; Troyan, V. I.; Habibulina, R. F.; Chubunova, E. V.; Yakovlev, V. P.

    2016-09-01

    In this paper, we discuss an idea of the experiment for excitation of the isomeric transition in thorium-229 nuclei by irradiating with electron beam targets with necessary physical characteristics. The chemical composition and bandgap of ThSi10O22 were determined by X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. It was found that the energy gap is equal to 7.7 eV and does not change when the target is exposed to a medium energy electron beam for a long time. This indicates that the compound possesses high electron-beam resistance. A quantitative estimation of the output function of isomeric thorium-229 nuclei generated by interaction of nuclei with the secondary electron flow formed by irradiating the solid-state ThSi10O22-based target is given. The estimation shows that ThSi10O22 is a promising thorium-containing target for investigating excitation of the nuclear low-lying isomeric transition in the thorium-229 isotope using medium-energy electrons.

  9. In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles

    NASA Astrophysics Data System (ADS)

    San-Miguel, Miguel A.; da Silva, Edison Z.; Zannetti, Sonia M.; Cilense, Mario; Fabbro, Maria T.; Gracia, Lourdes; Andrés, Juan; Longo, Elson

    2016-06-01

    Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.

  10. In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles.

    PubMed

    San-Miguel, Miguel A; da Silva, Edison Z; Zannetti, Sonia M; Cilense, Mario; Fabbro, Maria T; Gracia, Lourdes; Andrés, Juan; Longo, Elson

    2016-06-01

    Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements. PMID:27114472

  11. Influence of electron irradiation and heating on secondary electron yields from non-evaporable getter films observed with in situ x-ray photoelectron spectroscopy

    SciTech Connect

    Nishiwaki, Michiru; Kato, Shigeki

    2007-07-15

    Nonevaporable getter (NEG) film has been used for the beam ducts of particle accelerators as a pump having a large area. NEG film has been considered to have a low outgas rate induced by energetic particle irradiation and a low secondary electron yield (SEY). In this article, we focused on SEY measurements and in situ surface characterization of four NEG film samples using x-ray photoelectron spectroscopy (XPS). The NEG samples were TiZrV thin films deposited by magnetron sputtering at 100 or 300 deg. C on stainless steel. In addition, NEG samples saturated by CO gas exposure were prepared. SEY and XPS measurements of the surfaces of NEG samples were carried out under the conditions of as received, after electron beam irradiation, and after heating at 200 deg. C for 24 h. The maximum SEY values of the primary electron energy dependence, {delta}{sub max}, of all NEG samples decreased to around 1 by electron beam irradiation owing to a change in the carbon impurities, such as carbon oxide, carbon hydroxide, and hydrocarbon, to graphite state (graphitization) during the irradiation. After heating, {delta}{sub max} values of the NEG samples without CO gas exposure were also around 1 owing to the carbonization of Ti, Zr, and V. The {delta}{sub max}{approx_equal}1 was remarkably lower than that of copper baked under the same conditions. However, in saturated NEG samples, metal carbides were not produced to a significant extent by heating, and the {delta}{sub max} values did not decrease, showing values of 1.5-1.7.

  12. The effect of electron irradiation on the structure and the optical properties of silver particulate films deposited on modified thermoplastic polymer substrates

    NASA Astrophysics Data System (ADS)

    Kakkrannaya, A. Rakesha; Rao, K. Mohan; Tolpadi, Amita; Sanjeev, Ganesh; Pattabi, Manjunatha

    2016-03-01

    The silver (Ag) particulate films are prepared by the vacuum evaporation onto polystyrene (PS) substrates modified with 3-mercaptopropyltrimethoxysilane (MPTMS), pre-irradiated with the 8-MeV electron beam, held at a temperature 453 K. The effect of organosilane and electron irradiation dose on the Ag particulate structure is studied through optical spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED) pattern, atomic-force microscopy (AFM), and X-ray diffraction (XRD). The flat spectrum observed for the lower irradiation doses may be due to the formation of the clusters of different sizes and shapes. The band shift toward the higher wavelength is attributed to the increased aggregation leading to the formation of the larger-sized nanoclusters. A long tail extending to the higher wavelength region is also observed due to aggregation process. The FESEM studies indicate the formation of the silver nanoclusters. The decrease in the particle size with the increase in irradiation dose as seen through TEM studies is interpreted on the basis of polymer-metal particle interaction caused by the free radicals formed due to the electron irradiation of the MPTMS-modified PS substrates. The SAED pattern shows the crystalline nature of the silver particles formed on the pure PS and the MPTMS-modified PS substrates irradiated with the electron beam. The AFM studies show an increase in the average surface roughness of the silver films with the electron irradiation dose and the MPTMS concentration. XRD indicated the polycrystalline nature of silver film on the pre-irradiated PS substrates and formation of nanocrystallites of silver with preferred orientation on the MPTMS-modified PS substrates pre-irradiated with electron beam.

  13. The formation mechanism of periodic Zn nanocrystal arrays embedded in an amorphous layer by rapid electron beam irradiation.

    PubMed

    Shin, J W; Lee, J Y; No, Y S; Kim, T W; Choi, W K; Jin, S

    2008-07-23

    A periodic nano-island array of ∼7 nm diameter Zn single crystals embedded in an amorphous Zn(2x)Si(1-x)O(2) layer was created by using rapid electron beam irradiation for 50 s. A sequential process of 900 °C thermal annealing followed by electron beam irradiation induces the formation of an amorphous Zn(2x)Si(1-x)O(2) layer containing periodic Zn nanocrystals. It is shown that the periodic Zn crystal array can be produced with good control of their size and spacing. Possible formation mechanisms for the Zn crystal nano-islands are described on the basis of the experimental results.

  14. Degradation of dc characteristics of InGaAs/InP single heterojunction bipolar transistors under electron irradiation

    SciTech Connect

    Bandyopadhyay, A.; Subramanian, S.; Chandrasekhar, S.; Dentai, A.G.; Goodnick, S.M.

    1999-05-01

    The effects of high-energy ({approximately}1 MeV) electron irradiation on the dc characteristics of InGaAs/InP single heterojunction bipolar transistors (SHBT`s) are investigated. The device characteristics do not show any significant change for electron doses <10{sup 15}/cm{sup 2}. For higher doses, devices show a decrease in collector current, a degradation of common-emitter current gain, an increase in collector saturation voltage and an increase in the collector output conductance. A simple SPICE-like device model is developed to describe the dc characteristics of SHBT`s. The model parameters extracted from the measured dc characteristics of the devices before and after irradiation are used to get an insight into the physical mechanisms responsible for the degradation of the devices.

  15. Experimental and ab initio study of enhanced resistance to amorphization of nanocrystalline silicon carbide under electron irradiation

    NASA Astrophysics Data System (ADS)

    Jamison, Laura; Zheng, Ming-Jie; Shannon, Steve; Allen, Todd; Morgan, Dane; Szlufarska, Izabela

    2014-02-01

    The crystalline-to-amorphous transition in nanocrystalline silicon carbide (ncSiC) has been studied using 1.25 MeV electron irradiation. When compared to literature values for single crystal silicon carbide under electron irradiation, an increase in the dose to amorphization (DTA) was observed, indicative of an increase in radiation resistance. Factors that contribute to this improvement are grain refinement, grain texture, and a high density of stacking faults (SFs) in this sample of ncSiC. To test the effect of SFs on the DTA, density functional theory simulations were conducted. It was found that SFs reduced the energy barriers for both Si interstitial migration and the rate-limiting defect recovery reaction, which may explain the increased DTA.

  16. Damage threshold of platinum/carbon multilayers under hard X-ray free-electron laser irradiation.

    PubMed

    Kim, Jangwoo; Nagahira, Ayaka; Koyama, Takahisa; Matsuyama, Satoshi; Sano, Yasuhisa; Yabashi, Makina; Ohashi, Haruhiko; Ishikawa, Tetsuya; Yamauchi, Kazuto

    2015-11-01

    We evaluated the irradiation damage induced by hard X-ray free-electron lasers to platinum/carbon multilayers intended for use in a focusing reflective mirror. In order to determine the damage threshold, we compared X-ray reflectivities before and after irradiation at the first-order Bragg angle using a focused X-ray free-electron laser with a beam size of approximately 1 μm and a pulse energy ranging from 0.01 to 10 μJ at a photon energy of 10 keV. We confirmed that the damage threshold of the platinum/carbon multilayer with a bilayer period of 3 nm was 0.051 μJ/μm(2), which is sufficiently higher than that in practical applications.

  17. The influence of electron beam irradiation on the mechanical and thermal properties of Poly (ether-block-amide) blends

    NASA Astrophysics Data System (ADS)

    Murray, Kieran A.; Kennedy, James E.; McEvoy, Brian; Vrain, Olivier; Ryan, Damien; Cowman, Richard; Higginbotham, Clement L.

    2014-01-01

    High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce modifications and/or degradation to transpire in the material subsequent to treatment. To minimise this, Pebax was blended with three stabilisers where each formulation was subjected to electron beam radiation at doses of 25, 50 and 75 kGy. Mechanical testing revealed that the virgin Pebax and the Pebax blended with Irganox B215 provided the best radiation resistance in terms of the tensile strength, elongation at break and Young's modulus. Upon increase in radiation dose from 25 to 75 kGy, a gradual diminution was observed for the melt flow index (MFI) of the virgin Pebax, whereas Pebax blended with Irganox B215 had a minute effect on the properties post irradiation. This study provides evidence that the stabilisers used can either promote undesirable effects or enhance the radiation resistance of Pebax material following radiation exposure.

  18. Electron-beam irradiation induced transformation of Cu2(OH)3NO3 nanoflakes into nanocrystalline CuO

    NASA Astrophysics Data System (ADS)

    Padhi, S. K.; Gottapu, S. N.; Krishna, M. Ghanashyam

    2016-05-01

    The transmission electron microscope electron-beam (TEM e-beam) as a material modification tool has been demonstrated. The material modification is realised in the high-resolution TEM mode (largest condenser aperture, 150 μm, and 200 nm spot size) at a 200 keV beam energy. The Cu2(OH)3NO3 (CHN) nanoflakes used in this study were microwave solution processed that were layered single crystals and radiation sensitive. The single domain CHN flakes disintegrate into a large number of individual CuO crystallites within a 90 s span of time. The sequential bright-field, dark-field, and selected area electron diffraction modes were employed to record the evolved morphology, microstructural changes, and structural transformation that validate CHN modification. High-resolution transmission electron microscopy imaging of e-beam irradiated regions unambiguously supports the growth of CuO nanoparticles (11.8(3.2) nm in diameter). This study demonstrates e-beam irradiation induced CHN depletion, subsequent nucleation and growth of nanocrystalline CuO regions well embedded in the parent burnt porous matrix which can be useful for miniaturized sensing applications. NaBH4 induced room temperature reduction of CHN to elemental Cu and its printability on paper was also demonstrated.The transmission electron microscope electron-beam (TEM e-beam) as a material modification tool has been demonstrated. The material modification is realised in the high-resolution TEM mode (largest condenser aperture, 150 μm, and 200 nm spot size) at a 200 keV beam energy. The Cu2(OH)3NO3 (CHN) nanoflakes used in this study were microwave solution processed that were layered single crystals and radiation sensitive. The single domain CHN flakes disintegrate into a large number of individual CuO crystallites within a 90 s span of time. The sequential bright-field, dark-field, and selected area electron diffraction modes were employed to record the evolved morphology, microstructural changes, and structural

  19. Rocksalt ZnO nanocrystal formation by beam irradiation of wurtzite ZnO in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Lee, Sung Bo

    2016-10-01

    Under ambient conditions, ZnO crystallizes in a hexagonal wurtzite structure, but undergoes a phase transformation into a rocksalt structure with increasing hydrostatic pressure. However, in the present study, I have successfully demonstrated that intense beam irradiation of a wurtzite ZnO specimen in a transmission electron microscope produces nanoparticles of rocksalt ZnO as well as wurtzite ZnO, suggesting that the application of pressures is not a necessary condition for the formation of rocksalt ZnO.

  20. Energy absorption of free rare gas clusters irradiated by intense VUV pulses of a free electron laser

    NASA Astrophysics Data System (ADS)

    Schulz, J.; Wabnitz, H.; Laarmann, T.; Gürtler, P.; Laasch, W.; Swiderski, A.; Möller, Th.; de Castro, A. R. B.

    2003-07-01

    As one of the first experiments at the free electron laser of the TESLA Test Facility (TTF) the Coulomb explosion of Xenon clusters irradiated with high intensity pulses at a wavelength of 98 nm has been observed. Classical trajectory calculations have been performed in order to illuminate the energy absorption process. Comparison with typical parameters in the infrared regime shows that above barrier ionization is suppressed due to the fast oscillating field and thermionic ionization prevails.

  1. Design and Construction of Experiment for Direct Electron Irradiation of Uranyl Sulfate Solution: Bubble Formation and Thermal Hydraulics Studies

    SciTech Connect

    Chemerisov, Sergey; Gromov, Roman; Makarashvili, Vakho; Heltemes, Thad; Sun, Zaijing; Wardle, Kent E.; Bailey, James; Quigley, Kevin; Stepinski, Dominique; Vandegrift, George

    2014-10-01

    Argonne is assisting SHINE Medical Technologies in developing SHINE, a system for producing fission-product 99Mo using a D/T-accelerator to produce fission in a non-critical target solution of aqueous uranyl sulfate. We have developed an experimental setup for studying thermal-hydraulics and bubble formation in the uranyl sulfate solution to simulate conditions expected in the SHINE target solution during irradiation. A direct electron beam from the linac accelerator will be used to irradiate a 20 L solution (sector of the solution vessel). Because the solution will undergo radiolytic decomposition, we will be able to study bubble formation and dynamics and effects of convection and temperature on bubble behavior. These experiments will serve as a verification/ validation tool for the thermal-hydraulic model. Utilization of the direct electron beam for irradiation allows homogeneous heating of a large solution volume and simplifies observation of the bubble dynamics simultaneously with thermal-hydraulic data collection, which will complement data collected during operation of the miniSHINE experiment. Irradiation will be conducted using a 30-40 MeV electron beam from the high-power linac accelerator. The total electron-beam power will be 20 kW, which will yield a power density on the order of 1 kW/L. The solution volume will be cooled on the front and back surfaces and central tube to mimic the geometry of the proposed SHINE solution vessel. Also, multiple thermocouples will be inserted into the solution vessel to map thermal profiles. The experimental design is now complete, and installation and testing are in progress.

  2. Application of the mathematical Graf's addition theorem to the problem of electron energy absorption in laser-irradiated plasma

    NASA Astrophysics Data System (ADS)

    Krainov, V. P.

    2013-03-01

    The electron energy absorption in laser-irradiated plasma is determined by the sum of the rates of photon absorption and emission. These rates contain the square of the Bessel functions. It was shown that in a moderate laser field, terms with absorption and emission of several photons are large, but cancel exactly each other. Therefore, we should take into account terms with the absorption and emission of only one laser photon. This statement is proved analytically using Graf's theorem for Bessel functions.

  3. Study of electronic properties in proton- and electron-irradiated GaAlAs and GaAs solar cell materials

    NASA Technical Reports Server (NTRS)

    Li, S. S.

    1978-01-01

    Diagnostical measurement techniques such as dark I-V, C-V, the thermally insulated capacitance, and the deep level transient spectroscopy methods were employed to study defect properties in the proton-irradiated n-GaAs materials. Defect energy levels, thermal emission rates, and capture cross sections of electrons as well as trap densities were deduced from these measurements and the results are presented. Correlations between the measured defect parameters and the dark I-V characteristics of the n-GaAs Schottky barrier diodes are also discussed. Defect energy levels (i.e., electron traps) determined are also compared with published data in order to identify their physical origins.

  4. Raman shifts and in situ TEM electrical degradation of electron-irradiated monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Parkin, William M.; Balan, Adrian; Liang, Liangbo; Masih Das, Paul; Lamparski, Michael; Naylor, Carl; Rodriguez-Manzo, Julio A.; Johnson, Alan T.; Meunier, Vincent; Drndic, Marija

    We report how the presence of electron-beam-induced vacancies affects first-order Raman modes and correlate this effect with the evolution of in situ TEM two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a redshift in the E' Raman peak and a less pronounced blueshift in the A'1 peak with increasing electron dose. Using energy-dispersive X-ray spectroscopy, we show that irradiation causes partial removal of sulfur and correlate the dependence of the Raman peak shifts with S vacancy density (a few percent), which is confirmed by first-principles density functional theory calculations. Insitu device current measurements show exponential decrease in channel current upon irradiation. Our analysis demonstrates that the observed frequency shifts are intrinsic properties of the defective systems and that Raman spectroscopy can be used as a quantitative diagnostic tool to accurately characterize MoS2-based transport channels. This work was supported by the NIH Grant R21HG004767 and NIH Grant R21HG007856. Theoretical work at RPI was supported the NYSTAR program C080117 and the Office of Naval Research. C.H.N. and A.T.C.J. acknowledge support from UES/Air Force Research Lab.

  5. Enhancement in electron field emission in ultrananocrystalline and microcrystalline diamond films upon 100 MeV silver ion irradiation

    SciTech Connect

    Chen, H.-C.; Palnitkar, Umesh; Pong, W.-F.; Lin, I-N.; Singh, Abhinav Pratap; Kumar, Ravi

    2009-04-15

    Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag{sup 9+}-ions in a fluence of 5x10{sup 11} ions/cm{sup 2}. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E{sub 0}=3.2 V/mum and large EFE current density of J{sub e}=3.04 mA/cm{sup 2} for 5x10{sup 11} ions/cm{sup 2} heavy ion irradiated samples.

  6. High electronic excitations and ion beam mixing effects in high energy ion irradiated Fe/Si multilayers

    SciTech Connect

    Bauer, P.; Dufour, C.; Jaouen, C.; Marchal, G.; Pacaud, J.; Grilhe, J.; Jousset, J.C.

    1997-01-01

    M{umlt o}ssbauer spectroscopy ({sup 57}Fe) shows evidence for mixing effects induced by electronic energy deposition in nanoscale Fe/Si multilayers irradiated with swift heavy ions. A decrease in the mixing efficiency with electronic stopping power is reported; a threshold is found, under which iron environment modifications no longer occur. The kinetics of Fe{endash}Si phase formation after irradiation suggests the existence of three regimes: (i) for high excitation levels, a magnetic amorphous phase is formed directly in the wake of the incoming ion and an almost complete mixing is reached at low fluence (10{sup 13} U/cm{sup 2}); (ii) for low excitation levels, a paramagnetic Si-rich amorphous phase is favored at the interface while crystalline iron subsists at high fluences; (iii) for intermediate excitation levels, saturation effects are observed and the formation rate of both magnetic and paramagnetic phases points to direct mixing in the ion wake but with a reduced track length in comparison to U irradiation. The measured interfacial mixing cross section induced by electronic energy deposition suggests that a thermal diffusion process is mainly involved in addition to damage creation. {copyright} {ital 1997 American Institute of Physics.}

  7. Electron Resonance Decay into a Biological Function: Decrease in Viability of E. coli Transformed by Plasmid DNA Irradiated with 0.5-18 eV Electrons.

    PubMed

    Kouass Sahbani, S; Cloutier, P; Bass, A D; Hunting, D J; Sanche, L

    2015-10-01

    Transient negative ions (TNIs) are ubiquitous in electron-molecule scattering at low electron impact energies (0-20 eV) and are particularly effective in damaging large biomolecules. Because ionizing radiation generates mostly 0-20 eV electrons, TNIs are expected to play important roles in cell mutagenesis and death during radiotherapeutic cancer treatment, although this hypothesis has never been directly verified. Here, we measure the efficiency of transforming E. coli bacteria by inserting into the cells, pGEM-3ZfL(-) plasmid DNA that confers resistance to the antibiotic ampicillin. Before transformation, plasmids are irradiated with electrons of specific energies between 0.5 and 18 eV. The loss of transformation efficiency plotted as a function of irradiation energy reveals TNIs at 5.5 and 9.5 eV, corresponding to similar states observed in the yields of DNA double strand breaks. We show that TNIs are detectable in the electron-energy dependence of a biological process and can decrease cell viability.

  8. Combined Modality Therapy Including Intraoperative Electron Irradiation for Locally Recurrent Colorectal Cancer

    SciTech Connect

    Haddock, Michael G.; Miller, Robert C.; Nelson, Heidi; Pemberton, John H.; Dozois, Eric J.; Alberts, Steven R.; Gunderson, Leonard L.

    2011-01-01

    Purpose: To evaluate survival, relapse patterns, and prognostic factors in patients with colorectal cancer relapse treated with curative-intent therapy, including intraoperative electron radiation therapy (IOERT). Methods and Materials: From April 1981 through January 2008, 607 patients with recurrent colorectal cancer received IOERT as a component of treatment. IOERT was preceded or followed by external radiation (median dose, 45.5 Gy) in 583 patients (96%). Resection was classified as R0 in 227 (37%), R1 in 224 (37%), and R2 in 156 (26%). The median IOERT dose was 15 Gy (range, 7.5-30 Gy). Results: Median overall survival was 36 months. Five- and 10-year survival rates were 30% and 16%, respectively. Survival estimates at 5 years were 46%, 27%, and 16% for R0, R1, and R2 resection, respectively. Multivariate analysis revealed that R0 resection, no prior chemotherapy, and more recent treatment (in the second half of the series) were associated with improved survival. The 3-year cumulative incidence of central, local, and distant relapse was 12%, 23%, and 49%, respectively. Central and local relapse were more common in previously irradiated patients and in those with subtotal resection. Toxicity Grade 3 or higher partially attributable to IOERT was observed in 66 patients (11%). Neuropathy was observed in 94 patients (15%) and was more common with IOERT doses exceeding 12.5 Gy. Conclusions: Long-term survival and disease control was achievable in patients with locally recurrent colorectal cancer. Continued evaluation of curative-intent, combined-modality therapy that includes IOERT is warranted in this high-risk population.

  9. Reduction of Salmonella enterica serotype Poona and background microbiota on fresh-cut cantaloupe by electron beam irradiation.

    PubMed

    Palekar, Mangesh P; Taylor, T Matthew; Maxim, Joseph E; Castillo, Alejandro

    2015-06-01

    The efficacy of electron beam (e-beam) irradiation processing to reduce Salmonella enterica serotype Poona on surfaces of fresh-cut cantaloupe, and the impact of e-beam irradiation processing on the numbers of indigenous microorganisms were determined. Additionally, the D10-value for S. Poona reduction on the cut cantaloupe was also determined. Fresh-cut cantaloupe pieces, inoculated with S. Poona to 7.8 log10 CFU/g, were exposed to 0.0, 0.7, or 1.5 kGy. Surviving S. Poona, lactic acid bacteria (LAB), and fungi (yeasts, molds) were periodically enumerated on appropriate media over 21 days of storage at 5 °C. Cantaloupe surface pH was measured for irradiated cantaloupe across the 21 day storage period. To determine the D10-value of S. Poona, cantaloupe discs were inoculated and exposed to increasing radiation dosages between 0 and 1.06 kGy; surviving pathogen cells were selectively enumerated. S. Poona was significantly reduced by irradiation; immediate reductions following exposure to 0.7 and 1.5 kGy were 1.1 and 3.6 log10 CFU/g, respectively. After 21 days, S. Poona numbers were between 4.0 and 5.0 log10 CFU/g less than untreated samples at zero-time. Yeasts were not reduced significantly (p ≥ 0.05) by e-beam irradiation and grew slowly but steadily during storage. Counts of LAB and molds were initially reduced with 1.5 kGy (p<0.05) but then LAB recovered grew to high numbers, whereas molds slowly declined for irradiated and control samples. Cantaloupe pH declined during storage, with the greatest decrease in untreated control cantaloupe (p<0.05). The D10-value for S. Poona was determined to be 0.211 kGy, and this difference from the reductions observed in the cut cantaloupe studies may be due to the more precise dose distribution obtained in the thin and flat cantaloupe pieces used for the D10-value experiments. The effect of e-beam irradiation at the same doses used in this study was determined in previous studies to have no negative effect in the quality of

  10. Bremsstrahlung γ-ray generation by electrons from gas jets irradiated by laser pulses for radiographic testing

    NASA Astrophysics Data System (ADS)

    Oishi, Yuji; Nayuki, Takuya; Zhidkov, Alexei; Fujii, Takashi; Nemoto, Koshichi

    2012-07-01

    Electron generation from a gas jet irradiated by low energy femtosecond laser pulses is studied experimentally as a promising source of radiation for radioisotope-free γ-ray imaging systems. The calculated yield of γ-rays in the 0.5-2 MeV range, produced by low-average-power lasers and gas targets, exceeds the yields from solid tape targets up to 60 times. In addition, an effect of quasi-mono energetic electrons on γ-ray imaging is also discussed.

  11. Effects of gamma and electron beam irradiation on the properties of calendered cord fabrics

    NASA Astrophysics Data System (ADS)

    Aytaç, Ayşe; Deniz, Veli; Şen, Murat; Hegazy, El-Sayed; Güven, Olgun

    2010-03-01

    The effects of gamma and e-beam irradiation on mechanical and structural properties of nylon 66 (Ny 66), nylon 6 (Ny 6) and poly(ethylene terephthalate) (PET) fabrics used in tyres were investigated. The untreated (greige), treated cords and calendered fabrics were irradiated at different doses. It is found that the effects of high energy irradiation on greige, treated cords and calendered fabrics are similar. No protective effect of compounds used in calendering was observed against radiation-induced oxidative degradation. The deterioration effect of gamma irradiation on mechanical properties is much higher than that of e-beam irradiation for all types of samples. Limiting viscosity numbers of both gamma and e-beam irradiated nylon 6 and nylon 66 cords were found to decrease with increasing dose. It is concluded that PET calendered fabric has higher resistance to ionizing radiation. Ny 6 and Ny 66 calendered fabrics are more sensitive even at low doses. Therefore, the effects of high energy irradiation on tyre cords have to be taken into consideration during tyre design reinforced with particularly Ny fabrics if pre-vulcanization with high energy radiation is to be applied.

  12. Validation of total skin electron irradiation (TSEI) technique dosimetry data by Monte Carlo simulation.

    PubMed

    Nevelsky, Alexander; Borzov, Egor; Daniel, Shahar; Bar-Deroma, Rachel

    2016-01-01

    Total skin electron irradiation (TSEI) is a complex technique which requires many nonstandard measurements and dosimetric procedures. The purpose of this work was to validate measured dosimetry data by Monte Carlo (MC) simulations using EGSnrc-based codes (BEAMnrc and DOSXYZnrc). Our MC simulations consisted of two major steps. In the first step, the incident electron beam parameters (energy spectrum, FWHM, mean angular spread) were adjusted to match the measured data (PDD and profile) at SSD = 100 cm for an open field. In the second step, these parameters were used to calculate dose distributions at the treatment distance of 400 cm. MC simulations of dose distributions from single and dual fields at the treatment distance were performed in a water phantom. Dose distribution from the full treatment with six dual fields was simulated in a CT-based anthropomorphic phantom. MC calculations were compared to the available set of measurements used in clinical practice. For one direct field, MC calculated PDDs agreed within 3%/1 mm with the measurements, and lateral profiles agreed within 3% with the measured data. For the OF, the measured and calculated results were within 2% agreement. The optimal angle of 17° was confirmed for the dual field setup. Dose distribution from the full treatment with six dual fields was simulated in a CT-based anthropomorphic phantom. The MC-calculated multiplication factor (B12-factor), which relates the skin dose for the whole treatment to the dose from one calibration field, for setups with and without degrader was 2.9 and 2.8, respectively. The measured B12-factor was 2.8 for both setups. The difference between calculated and measured values was within 3.5%. It was found that a degrader provides more homogeneous dose distribution. The measured X-ray contamination for the full treatment was 0.4%; this is compared to the 0.5% X-ray contamination obtained with the MC calculation. Feasibility of MC simulation in an anthropomorphic phantom

  13. Electron Microscopic Evaluation and Fission Product Identification of Irradiated TRISO Coated Particles from the AGR-1 Experiment: A Preliminary Review

    SciTech Connect

    IJ van Rooyen; DE Janney; BD Miller; PA DEmkowicz; J Riesterer

    2014-05-01

    Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this paper a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objectives of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. Microstructural characterization focused on fission-product precipitates in the SiC-IPyC interface, the SiC layer and the fuel-buffer interlayer. The results provide significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates with significantly higher concentrations of Pd and U. Different approaches to resolving this problem are discussed. An initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations were observed and no debonding of the SiC-IPyC interlayer as a result of irradiation was observed for the samples investigated. Lessons learned from the post-irradiation examination are described and future actions are recommended.

  14. Electron microscopic evaluation and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment: A preliminary Study

    SciTech Connect

    I J van Rooyen; D E Janney; B D Miller; J L Riesterer; P A Demkowicz

    2012-10-01

    ABSTRACT Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this presentation a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objective of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. The characterization emphasized fission-product precipitates in the SiC-IPyC interface, SiC layer and the fuel-buffer interlayer, and provided significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentration Ag in precipitates with significantly higher concentrations of contain Pd and U. Different approaches to resolving this problem are discussed. Possible microstructural differences between particles with high and low releases of Ag particles are also briefly discussed, and an initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations or debonding of the SiC-IPyC interlayer as a result of irradiation were observed. Lessons learned from the post-irradiation examination are described and future actions are recommended.

  15. Examination of gamma-irradiated fruits and vegetables by electron spin resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Desrosiers, Marc F.; McLaughlin, William L.

    The ESR spectra of the seeds, pits, shells, and skins of a variety of irradiated fruits and vegetables were measured. All spectra, control and irradiated, contained a single resonance with a g-factor of 2.00. Additional resonances due to Mn 2+ were observed for the drupelets of blackberries and red raspberries. An unusual radiation-induced radical was observed for irradiated mango seed; however, the signal decayed completely within a few days. It was concluded that only in a few specialized cases could the ESR resonances observed be suitable for postirradiation monitoring or dosimetry.

  16. Study of irradiated Hadfield steel using transmission Mössbauer spectroscopy with high velocity resolution and conversion electron Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Semionkin, V. A.; Neshev, F. G.; Tsurin, V. A.; Milder, O. B.; Oshtrakh, M. I.

    2010-03-01

    Proton irradiated Hadfield steel foil was studied using transmission Mössbauer spectroscopy with high velocity resolution and conversion electron Mössbauer spectroscopy. It was shown that proton irradiation leads to structural changes in the foil as well as to surface oxidation with ferric hydrous oxide formation (ferrihydrite). Moreover, oxidation on the foil underside was higher than on the foil right side.

  17. Fat Necrosis After Partial-Breast Irradiation With Brachytherapy or Electron Irradiation Versus Standard Whole-Breast Radiotherapy-4-Year Results of a Randomized Trial

    SciTech Connect

    Loevey, Katalin Fodor, Janos; Major, Tibor; Szabo, Eva; Orosz, Zsolt; Sulyok, Zoltan; Janvary, Levente; Froehlich, Georgina; Kasler, Miklos; Polgar, Csaba

    2007-11-01

    Purpose: To examine the incidence and clinical relevance of fat necrosis after accelerated partial-breast irradiation (PBI) using interstitial high-dose-rate brachytherapy (HDR-BT) in comparison with partial-breast electron irradiation (ELE) and whole-breast irradiation (WBI). Methods and Materials: Between 1998 and 2004, 258 early-stage breast cancer patients were randomized to receive 50 Gy WBI (n = 130) or PBI (n = 128). The latter consisted of either 7 x 5.2 Gy HDR-BT (n = 88) or 50 Gy ELE (n = 40). The incidence of fat necrosis, its impact on cosmetic outcome, accompanying radiologic features, and clinical symptoms were evaluated. Results: The 4-year actuarial rate of fat necrosis was 31.1% for all patients, and 31.9%, 36.5%, and 17.7% after WBI, HDR-BT and ELE, respectively (p{sub WBI/HDR-BT} = 0.26; p{sub WBI/ELE} = 0.11; p{sub ELE/HDR-BT} = 0.025). The respective rate of asymptomatic fat necrosis was 20.2%, 25.3%, and 10% of patients. The incidence of symptomatic fat necrosis was not significantly different after WBI (8.5%), HDR-BT (11.4%), and ELE (7.5%). Symptomatic fat necrosis was significantly associated with a worse cosmetic outcome, whereas asymptomatic fat necrosis was not. Fat necrosis was detectable with mammography and/or ultrasound in each case. Additional imaging examinations were required in 21% of cases and aspiration cytology in 42%. Conclusions: Asymptomatic fat necrosis is a common adverse event of breast-conserving therapy, having no significant clinical relevance in the majority of the cases. The incidence of both symptomatic and asymptomatic fat necrosis is similar after conventional WBI and accelerated partial-breast HDR-BT.

  18. Influence of the physical structure of irradiated starches on their electron spin resonance spectra kinetics

    SciTech Connect

    Raffi, J.J.; Agnel, J.P.L.

    1983-06-23

    This study deals with the shape and kinetic changes of the ESR spectra of eight irradiated starchs, from several hours to several months after ..gamma..-irradiation. Whatever the origin and water content of the starches two major radicals or groups of radicals are observed. The kinetic law depends on the water content; two main zones are pointed out which are relative to the amorphous and crystalline parts of starches.

  19. Electron spin resonance of gamma-irradiated poly/ethylene 2,6-naphthalene dicarboxylate/.

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Pezdirtz, G. F.

    1971-01-01

    The two types of radicals trapped in gamma-irradiated PEN 2,6 are identified by ESR as - O - CH - CH2 - O - (radical I) and a radical located on the naphthalene ring (radical II). The concentrations of the radicals in the gross polyer are 10 to 20% of I and 80 to 90% of II. Similar trapped radicals are established in beta-irradiated PET, a structurally related polymer.

  20. Best use of high-voltage, high-powered electron beams: a new approach to contract irradiation services

    NASA Astrophysics Data System (ADS)

    Watanabe, T.

    2000-03-01

    Japan's first high-voltage, high-powered electron beam processing center is scheduled to come on-line during the first half of 1999. The center explores both challenges and opportunities of how best to use the 200 kW 10 MeV unit and its 5 MeV X-ray line. In particular, Nuclear Fuel Industries, Ltd. (NFI) has expanded the traditional model of a contract irradiation facility to include a much broader scope of services such as door-to-door transport, storage, and direct distribution to its customer's end-users. The new business scope not only finds new value-added components in a competitive marketplace, but serves to provide a viable mechanism to take advantage of the processing logistics of high throughput irradiation units. As such, the center features a high-capacity warehousing system, monitored by a newly developed PCMS (plant control management system), which has been comprehensively integrated into the irradiation unit's handling system, and will require only minimal human resources for its high rate of material handling. The identification and development of initial markets for this first unit will be discussed, concluding with how this same operational philosophy can help break open new irradiation segments in medical devices, consumer goods, animal feed, and food markets and NFI's other efforts in these same areas.