WorldWideScience

Sample records for low-energy electron irradiation

  1. Food irradiation by low energy electrons

    International Nuclear Information System (INIS)

    Bird, J.R.

    1985-01-01

    For some special cases, the use of low energy electrons has advantages over the use of gamma-rays or higher energy electrons for the direct irradiation of food. These advantages arise from details of the interaction processes which are responsible for the production of physical, chemical and biological effects. Factors involved include depth of penetration, dose distribution, irradiation geometry, the possible production of radioactivity and costs

  2. Challenges in validating radiation sterilization with low energy electron irradiation

    International Nuclear Information System (INIS)

    Miller, A.; Helt-Hansen, J.

    2011-01-01

    Complete text of publication follows. Low energy electron irradiation (80-300 keV) is used increasingly for sterilization or decontamination in connection with isolators for aseptic filling lines in the pharmaceutical industry. It is not defined how validation for this process shall be carried out. A method can be derived from the medical device standard for radiation sterilization, ISO 11137, because the principles described in this standard can be applied to almost any industrial irradiation process. The validations elements are: Process definition, concerning specification of the dose required for the process and the maximum acceptable dose for the product. Installation qualification, concerning acceptance the irradiation facility. Operational qualification, concerning characterization of the facility. Performance qualification, concerning setting up the process. Process control, concerning routine monitoring. The limited penetration of the low energy electrons leads to problems with respect to executing these validation steps. This paper discusses these problems, and shows with examples how they can be solved.

  3. Dose controlled low energy electron irradiator for biomolecular films.

    Science.gov (United States)

    Kumar, S V K; Tare, Satej T; Upalekar, Yogesh V; Tsering, Thupten

    2016-03-01

    We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at -20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

  4. Dose controlled low energy electron irradiator for biomolecular films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. V. K., E-mail: svkk@tifr.res.in; Tare, Satej T.; Upalekar, Yogesh V.; Tsering, Thupten [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

    2016-03-15

    We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at −20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

  5. Silicon passivation study under low energy electron irradiation conditions

    International Nuclear Information System (INIS)

    Cluzel, R.

    2010-01-01

    Backside illuminated thinned CMOS (Complementary Metal Oxide Semiconductor) imaging system is a technology developed to increase the signal to noise ratio and the sensibility of such sensors. This configuration is adapted to the electrons detection from the energy range of [1 - 12 keV]. The impinging electron creates by multiplication several hundreds of secondary electrons close to the surface. A P ++ highly-doped passivation layer of the rear face is required to reduce the secondary electron surface recombination rate. Thanks to the potential barrier induced by the P ++ layer, the passivation layer increases the collected charges number and so the sensor collection gain. The goal of this study is to develop some experimental methods in order to determine the effect of six different passivation processes on the collection gain. Beforehand, the energy profile deposited by an incident electron is studied with the combination of Monte-Carlo simulations and some analytical calculations. The final collection gain model shows that the mirror effect from the passivation layer is a key factor at high energies whereas the passivation layer has to be as thin as possible at low energies. A first experimental setup which consists in irradiating P ++ /N large diodes allows to study the passivation process impacts on the surface recombinations. Thanks to a second setup based on a single event upset directly on thinned CMOS sensor, passivation techniques are discriminated in term of mirror effect and the implied spreading charges. The doping atoms activation laser annealing is turn out to be a multiplication gain inhomogeneity source impacting directly the matrix uniformity. (author)

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

    Science.gov (United States)

    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.

  7. Low-energy electron irradiation assisted diffusion of gold nanoparticles in polymer matrix

    International Nuclear Information System (INIS)

    Deore, Avinash V.; Bhoraskar, V.N.; Dhole, S.D.

    2014-01-01

    A simple and controllable method to synthesize nanoparticles in the surface region of polymers was used by low energy electron irradiation. Using this method, gold nanoparticles have been synthesized by irradiating gold coated PVA (Polyvinyl Alcohol) sheets. This method was easy in operation and even period of few minutes was sufficient to obtain the nanoparticles. The coatings (∼10 μm) made from a mixture of ethanol and HAuCl 4 on PVA sheets (∼150 μm) by simple drop cast method were irradiated with 30 keV electrons, at room temperature and 10 −6 mbar vacuum level. The electron fluence was varied from coating to coating in the range of 0 to 24×10 15 e/cm 2 . The irradiated samples were characterized by the UV–Vis, XRD, SEM and RBS techniques. The plasmon absorption peak at ∼539 nm in UV–Vis spectra was an evidence for the initiation of the growth of gold nanoparticles. The X-ray diffraction results and the blue shift in the plasmon absorption peak reveal that the size of nanoparticles could be tailored in the range from 58 to 40 nm by varying the electron fluence. The diffusion of gold in the PVA was confirmed by the Rutherford backscattering spectroscopy and scanning electron microscopy techniques. This method of synthesis of metal nanoparticles by low energy electron beam irradiation has the key importance in the development of new fabrication techniques for nanomaterials. - Highlights: • The results indicate that low energy electrons can effectively be used for the synthesis of nanoparticles of different sizes. • This study leads to a definite conclusion that gold nanoparticles have been synthesized in surface region of the PVA sheet. • The size of nanoparticles decreases with increasing electron fluence. • The depth of diffusion of Au atoms at maximum fluence was found to be ∼1.5 μm

  8. Direct nanopatterning of polymer/silver nanoblocks under low energy electron beam irradiation.

    Science.gov (United States)

    El Mel, Abdel-Aziz; Stephant, Nicolas; Gautier, Romain

    2016-10-06

    In this communication, we report on the growth, direct writing and nanopatterning of polymer/silver nanoblocks under low energy electron beam irradiation using a scanning electron microscope. The nanoblocks are produced by placing a droplet of an ethylene glycol solution containing silver nitrate and polyvinylpyrrolidone diluted in ethanol directly on a hot substrate heated up to 150 °C. Upon complete evaporation of the droplet, nanospheres, nano- and micro-triangles and nanoblocks made of silver-containing polymers, form over the substrate surface. Considering the nanoblocks as a model system, we demonstrate that such nanostructures are extremely sensitive to the e-beam extracted from the source of a scanning electron microscope operating at low acceleration voltages (between 5 and 7 kV). This sensitivity allows us to efficiently create various nanopatterns (e.g. arrays of holes, oblique slits and nanotrenches) in the material under e-beam irradiation. In addition to the possibility of writing, the nanoblocks revealed a self-healing ability allowing them to recover a relatively smooth surface after etching. Thanks to these properties, such nanomaterials can be used as a support for data writing and erasing on the nanoscale under low energy electron beam irradiation.

  9. Effect of low energy electron irradiation on DNA damage by Cu{sup 2+} ion

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Hyung Ah; Cho, Hyuck [Dept. of Physics, Chungnam National University, Daejeon (Korea, Republic of); Park, Yeun Soo [Plasma Technology Research Center, National Fusion Research Institute, Gunsan (Korea, Republic of)

    2017-03-15

    The combined effect of the low energy electron (LEE) irradiation and Cu{sup 2+} ion on DNA damage was investigated. Lyophilized pBR322 plasmid DNA films with various concentrations (1–15 mM) of Cu{sup 2+} ion were independently irradiated by monochromatic LEEs with 5 eV. The types of DNA damage, single strand break (SSB) and double strand break (DSB), were separated and quantified by gel electrophoresis. Without electron irradiation, DNA damage was slightly increased with increasing Cu ion concentration via Fenton reaction. LEE-induced DNA damage, with no Cu ion, was only 6.6% via dissociative electron attachment (DEA) process. However, DNA damage was significantly increased through the combined effect of LEE-irradiation and Cu ion, except around 9 mM Cu ion. The possible pathways of DNA damage for each of these different cases were suggested. The combined effect of LEE-irradiation and Cu ion is likely to cause increasing dissociation after elevated transient negative ion state, resulting in the enhanced DNA damage. For the decrease of DNA damage at around 9-mM Cu ion, it is assumed to be related to the structural stabilization due to DNA inter- and intra-crosslinks via Cu ion.

  10. A permanent magnet electron beam spread system used for a low energy electron irradiation accelerator

    International Nuclear Information System (INIS)

    Huang Jiang; Xiong Yongqian; Chen Dezhi; Liu Kaifeng; Yang Jun; Li Dong; Yu Tiaoqin; Fan Mingwu; Yang Bo

    2014-01-01

    The development of irradiation processing industry brings about various types of irradiation objects and expands the irradiation requirements for better uniformity and larger areas. This paper proposes an innovative design of a permanent magnet electron beam spread system. By clarifying its operation principles, the author verifies the feasibility of its application in irradiation accelerators for industrial use with the examples of its application in electron accelerators with energy ranging from 300 keV to 1 MeV. Based on the finite element analyses of electromagnetic fields and the charged particle dynamics, the author also conducts a simulation of electron dynamics in magnetic field on a computer. The results indicate that compared with the traditional electron beam scanning system, this system boosts the advantages of a larger spread area, non-power supply, simple structure and low cost, etc., which means it is not only suitable for the irradiation of objects with the shape of tubes, strips and panels, but can also achieve a desirable irradiation performance on irregular constructed objects of large size. (authors)

  11. Pathogens Inactivated by Low-Energy-Electron Irradiation Maintain Antigenic Properties and Induce Protective Immune Responses

    Science.gov (United States)

    Fertey, Jasmin; Bayer, Lea; Grunwald, Thomas; Pohl, Alexandra; Beckmann, Jana; Gotzmann, Gaby; Casado, Javier Portillo; Schönfelder, Jessy; Rögner, Frank-Holm; Wetzel, Christiane; Thoma, Martin; Bailer, Susanne M.; Hiller, Ekkehard; Rupp, Steffen; Ulbert, Sebastian

    2016-01-01

    Inactivated vaccines are commonly produced by incubating pathogens with chemicals such as formaldehyde or β-propiolactone. This is a time-consuming process, the inactivation efficiency displays high variability and extensive downstream procedures are often required. Moreover, application of chemicals alters the antigenic components of the viruses or bacteria, resulting in reduced antibody specificity and therefore stimulation of a less effective immune response. An alternative method for inactivation of pathogens is ionizing radiation. It acts very fast and predominantly damages nucleic acids, conserving most of the antigenic structures. However, currently used irradiation technologies (mostly gamma-rays and high energy electrons) require large and complex shielding constructions to protect the environment from radioactivity or X-rays generated during the process. This excludes them from direct integration into biological production facilities. Here, low-energy electron irradiation (LEEI) is presented as an alternative inactivation method for pathogens in liquid solutions. LEEI can be used in normal laboratories, including good manufacturing practice (GMP)- or high biosafety level (BSL)-environments, as only minor shielding is necessary. We show that LEEI efficiently inactivates different viruses (influenza A (H3N8), porcine reproductive and respiratory syndrome virus (PRRSV), equine herpesvirus 1 (EHV-1)) and bacteria (Escherichia coli) and maintains their antigenicity. Moreover, LEEI-inactivated influenza A viruses elicit protective immune responses in animals, as analyzed by virus neutralization assays and viral load determination upon challenge. These results have implications for novel ways of developing and manufacturing inactivated vaccines with improved efficacy. PMID:27886076

  12. Theory of emission spectra from metal films irradiated by low energy electrons near normal incidence

    International Nuclear Information System (INIS)

    Kretschmann, E.; Callcott, T.A.; Arakawa, E.T.

    1980-01-01

    The emission spectrum produced by low energy electrons incident on a rough metal surface has been calculated for a roughness auto-correlation function containing a prominent peak at a high wave vector. For low energy electrons near normal incidence, the high wavevector peak dominates the roughness coupled surface plasmon radiation (RCSPR) process. The calculation yields estimates of the ratio of RCSPR to transition radiation, the dependence of emission intensity on electron energy and the shape and position of the RCSPR peak. The most interesting result is that the high-wavevector roughness can split the RCSPR radiation into peaks lying above and below the asymptotic surface plasma frequency. The results are compared with data from Ag in the following paper. (orig.)

  13. Low energy electron irradiation induced carbon etching: Triggering carbon film reacting with oxygen from SiO{sub 2} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Cheng [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Wang, Chao, E-mail: cwang367@szu.edu.cn, E-mail: dfdiao@szu.edu.cn; Diao, Dongfeng, E-mail: cwang367@szu.edu.cn, E-mail: dfdiao@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China)

    2016-08-01

    We report low-energy (50–200 eV) electron irradiation induced etching of thin carbon films on a SiO{sub 2} substrate. The etching mechanism was interpreted that electron irradiation stimulated the dissociation of the carbon film and SiO{sub 2}, and then triggered the carbon film reacting with oxygen from the SiO{sub 2} substrate. A requirement for triggering the etching of the carbon film is that the incident electron penetrates through the whole carbon film, which is related to both irradiation energy and film thickness. This study provides a convenient electron-assisted etching with the precursor substrate, which sheds light on an efficient pathway to the fabrication of nanodevices and nanosurfaces.

  14. Dose estimation in low-energy electron beam irradiation for industrial purposes

    International Nuclear Information System (INIS)

    Kijima, Toshiyuki; Nakase, Yoshiaki.

    1997-03-01

    A Monte Carlo method for the passage of electrons based on a single scattering model is developed, in which the relativistic correction has been taken into accounted. A code based on this method is operable on personal computers, and has been applied to analyze electron behavior in a layered system consisting Ti as an accelerator window, air, cellulose triacetate (CTA) and backing material irradiated by mainly 300 keV electrons. The energy spectra and the angular distributions of electrons on CTA surface as well as depth-dose distributions of energy deposition in the CTA for various backing materials have been obtained. Some of these results are compared with experimentals, and showed fairly good agreement. (author). 322 refs

  15. Development of low energy electron beam irradiation techniques. Application to sticking adhesive

    International Nuclear Information System (INIS)

    Ito, Hisashi; Enomoto, Ichiro

    1997-01-01

    Sticking adhesives were developed by use of blend with electron beam crosslinked type stylene - isoprene block copolymer (SIS) as a basic component. The sticking adhesive has object to change from sticking to adhesion and peeling by irradiation. SIS was blended with reactive monomer and resins or alicyclic hydrocarbon as tackifier and investigated. The results showed change of peel force by irradiation was influenced by compatibility, composition and the quality of objective materials. SIS such as Kraton D1320X (Shell Co. Ltd.) and tackifier such as rosin (ROSIN) and arcone P100 (ARP) were used at the basic ratio SIS/tackifier=64. Modified urethane acrylate (UA306H), isobornyl acrylate (IBXA), epoxy ester (3002M), lauryl methacrylate (LM) and lauryl acrylate (LA) were used as monomer. The large changes of peel force were observed by blends with UA306H or 3002M of which properties were incompatibility. These results indicated that we made possible to control the peel force by irradiation by means of adding the specific incompatibility monomer to the mixture of SIS and tackifier. (S.Y.)

  16. Development of low energy electron beam irradiation technology. Application to cohesive and adhesive agents

    International Nuclear Information System (INIS)

    Ito, Hisashi; Enomoto, Ichiro; Tsuchiya, Mitsuaki

    1996-01-01

    The hightening of the cohesive and adhesive performances of rubber cohesive and adhesive agents, of which the main component is electron beam-cross-linked styrene-isoprene block copolymer (SIS), was tried. Cohesive and adhesive agents are cohesive agents at the time of use, but change to adhesive property by the lapse of time or the means using heat, light or radiation, and further, partially to separating property. This time, as a cohesion-giving agent, ARKON P-100 system was examined, and the heightening of adhesive performance including the improvement of the heat resistance and solvent endurance, which are the demerits of rubber, was investigated. Also the difference of the cohesive and adhesive performances due to the kinds of cohesion-giving agents was examined. The samples were prepared by irradiating the films on which the SIS was applied. The measurement of gel proportion, the holding force test at elevated temperature, the measurement of DSC and 180deg separation test were carried out. Respective testing methods and the results are reported. By electron beam irradiation, the heat resistance and solvent endurance were improved without affecting the separation force. (K.I.)

  17. Electrical performance of the InGaP solar cell irradiated with low energy electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, Yasuki; Okuda, Shuichi; Kojima, Takeo; Oka, Takashi [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai City, Osaka (Japan); Kawakita, Shirou; Imaizumi, Mitsuru; Kusawake, Hiroaki [Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki (Japan)

    2015-06-15

    The investigation of the radiation degradation characteristics of InGaP space solar cells is important. In order to understand the mechanism of the degradation by radiation the samples of the InGaP solar cell were irradiated in vacuum and at ambient temperature with electron beams from a Cockcroft-Walton type accelerator at Osaka Prefecture University. The threshold energies for recoil were obtained by theoretical calculation. The energies and the fluences of the electron beams were from 60 to 400 keV and from 3 x 10{sup 14} to 3 x 10{sup 16} cm{sup -2}, respectively. The light-current-voltage measurements were performed. The degradation of Isc caused by the defects related to the phosphorus atoms was observed and the degradation was suppressed by irradiation at an energy higher than the threshold energy for recoiling Indium atoms. At an energy of 60 keV, where the recoil does not occur, the V{sub oc} was degraded. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Trial production of low protein irradiated natural rubber latex by low energy electron beam in pilot scale

    International Nuclear Information System (INIS)

    Utama, Marga; Yoshii, F.; Kume, T.

    2006-01-01

    Three importance factors for producing low protein by low energy electron beam (250 keV/10 mA) irradiation in pilot scale (20 liters per bath) with 1,9-nonediol diacrylate (NDA) namely: maturation time of natural rubber latex before irradiation, treatment of irradiated natural rubber latex (INRL) before and after centrifugation, and standard irradiation method has been carried out. The results showed that the optimum irradiation time for producing INRL with 5 phr (part hundred ratio of rubber) of NDA as sensitize agent, and with the rotation speed of agitation 210 rpm (rotation per minutes) was between 20-30 minutes. By using this condition tensile strength of the INRL film was 26 MPa. The maturation of natural rubber latex before irradiation is the key for driving the quality of INRL. Water extractable protein content of INRL after leaching in 1% ammonia solution for 30 minutes at room temperature was around 47 μ/g, and after adding with 1 phr of PVA (poly vinyl alcohol) or 0.1 phr CMC (carboxy methyl cellulose) the water extractable protein content decrease less than 6 μ/g. (author)

  19. Methods for measurement of electron emission yield under low energy electron-irradiation by collector method and Kelvin probe method

    Energy Technology Data Exchange (ETDEWEB)

    Tondu, Thomas; Belhaj, Mohamed; Inguimbert, Virginie [Onera, DESP, 2 Avenue Edouard Belin, 31400 Toulouse (France); Onera, DESP, 2 Avenue Edouard Belin, 31400 Toulouse, France and Fondation STAE, 4 allee Emile Monso, BP 84234-31432, Toulouse Cedex 4 (France); Onera, DESP, 2 Avenue Edouard Belin, 31400 Toulouse (France)

    2010-09-15

    Secondary electron emission yield of gold under electron impact at normal incidence below 50 eV was investigated by the classical collector method and by the Kelvin probe method. The authors show that biasing a collector to ensure secondary electron collection while keeping the target grounded can lead to primary electron beam perturbations. Thus reliable secondary electron emission yield at low primary electron energy cannot be obtained with a biased collector. The authors present two collector-free methods based on current measurement and on electron pulse surface potential buildup (Kelvin probe method). These methods are consistent, but at very low energy, measurements become sensitive to the earth magnetic field (below 10 eV). For gold, the authors can extrapolate total emission yield at 0 eV to 0.5, while a total electron emission yield of 1 is obtained at 40{+-}1 eV.

  20. Methods for measurement of electron emission yield under low energy electron-irradiation by collector method and Kelvin probe method

    International Nuclear Information System (INIS)

    Tondu, Thomas; Belhaj, Mohamed; Inguimbert, Virginie

    2010-01-01

    Secondary electron emission yield of gold under electron impact at normal incidence below 50 eV was investigated by the classical collector method and by the Kelvin probe method. The authors show that biasing a collector to ensure secondary electron collection while keeping the target grounded can lead to primary electron beam perturbations. Thus reliable secondary electron emission yield at low primary electron energy cannot be obtained with a biased collector. The authors present two collector-free methods based on current measurement and on electron pulse surface potential buildup (Kelvin probe method). These methods are consistent, but at very low energy, measurements become sensitive to the earth magnetic field (below 10 eV). For gold, the authors can extrapolate total emission yield at 0 eV to 0.5, while a total electron emission yield of 1 is obtained at 40±1 eV.

  1. Surface sterilization by low energy electron beams

    International Nuclear Information System (INIS)

    Sekiguchi, Masayuki; Tabei, Masae

    1989-01-01

    The germicidal effectiveness of low energy electron beams (175 KV) against bacterial cells was investigated. The dry spores of Bacillus pumilus ATCC 27142 and Bacillus globigii ATCC 9372 inoculated on carrier materials and irradiated by gamma rays showed the exponential type of survival curves whereas they showed sigmoidal ones when exposed to low energy electron beams. When similarly irradiated, the wet spores inoculated on membrane filter showed the same survival curves as the dry spores inoculated on carrier materials. The wet vegetative cells of Escherichia coli ATCC 25922 showed exponential curves when exposed to gamma and electron beam irradiation. Low energy electron beams in air showed little differences from nitrogen stream in their germicidal effectiveness against dry spores of B. pumilus. The D values of B. pumilus spores inoculated on metal plates decreased as the amounts of backscattering electrons from the plates increased. There was adequate correlation between the D value (linear region of survival curve), average D value (6D/6) and 1% survival dose and backscattering factor. Depth dose profile and backscatterig dose of low energy electron beams were measured by radiochromic dye film dosimeter (RCD). These figures were not always in accord with the observed germicidal effectiveness against B. pumilus spores because of varying thickness of RCD and spores inoculated on carrier material. The dry spores were very thin and this thinness was useful in evaluating the behavior of low energy electrons. (author)

  2. Loss of cellular transformation efficiency induced by DNA irradiation with low-energy (10 eV) electrons.

    Science.gov (United States)

    Kouass Sahbani, Saloua; Sanche, Leon; Cloutier, Pierre; Bass, Andrew D; Hunting, Darel J

    2014-11-20

    Low energy electrons (LEEs) of energies less than 20 eV are generated in large quantities by ionizing radiation in biological matter. While LEEs are known to induce single (SSBs) and double strand breaks (DSBs) in DNA, their ability to inactivate cells by inducing nonreparable lethal damage has not yet been demonstrated. Here we observe the effect of LEEs on the functionality of DNA, by measuring the efficiency of transforming Escherichia coli with a [pGEM-3Zf (-)] plasmid irradiated with 10 eV electrons. Highly ordered DNA films were prepared on pyrolitic graphite by molecular self-assembly using 1,3-diaminopropane ions (Dap(2+)). The uniformity of these films permits the inactivation of approximately 50% of the plasmids compared to transforming cluster damage into DSBs by digestion with repair enzymes, also occurred relatively infrequently. The exact nature of the lethal damage remains unknown, but it is probably a form of compact cluster damage in which the lesions are too close to be revealed by purified repair enzymes. In addition, this damage is either not repaired or is misrepaired by E. coli, since it results in plasmid inactivation, when they contain an average of three lesions. Comparison with previous results from a similar experiment performed with γ-irradiated plasmids indicates that the type of clustered DNA lesions, created directly on cellular DNA by LEEs, may be more difficult to repair than those produced by other species from radiolysis.

  3. P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI)

    International Nuclear Information System (INIS)

    Amano, Hiroshi; Kito, Masahiro; Hiramatsu, Kazumasa

    1989-01-01

    Distinct p-type conduction is realized with Mg-doped GaN by the low-energy electron-beam irradiation (LEEBI) treatment, and the properties of the GaN p-n junction LED are reported for the first time. It was found that the LEEBI treatment drastically lowers the resistivity and remarkably enhances the PL efficiency of MOVPE-grown Mg-doped GaN. The Hall effect measurement of this Mg-doped GaN treated with LEEBI at room temperature showed that the hole concentration is ∼2·10 16 cm -3 , the hole mobility is ∼8 cm 2 /V·s and the resistivity is ∼35Ω· cm. The p-n junction LED using Mg-doped GaN treated with LEEBI as the p-type material showed strong near-band-edge emission due to the hole injection from the p-layer to the n-layer at room temperature. (author)

  4. Generic roll-to-roll compatible method for insolubilizing and stabilizing conjugated active layers based on low energy electron irradiation

    DEFF Research Database (Denmark)

    Helgesen, Martin; Carlé, Jon Eggert; Helt-Hansen, Jakob

    2014-01-01

    Irradiation of organic multilayer films is demonstrated as a powerful method to improve several properties of polymer thin films and devices derived from them. The chemical cross‐linking that is the direct result of the irradiation with ∼100 keV electrons is fast and has a penetration power...... stability. The method is fast, generic, contactless, and fully compatible with high‐speed roll‐to‐roll processing of i.e. polymer solar cells at web speeds in excess of 60 m min−1. We employ fully printed, flexible, and foil‐based indium‐tin‐oxide free polymer solar cells in this study to demonstrate...

  5. Radiation damage of multipixel Geiger-mode avalanche photodiodes irradiated with low-energy γ's and electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Y.; Yun, Y. B. [Yonsei University, Seoul (Korea, Republic of); Ha, J. M. [Yonsei University, Seoul (Korea, Republic of); Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of); Lee, J. S.; Yoon, Y. S. [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of); Eun, J. W. [Namseoul University, Cheonan (Korea, Republic of)

    2012-05-15

    A few types of multipipixel Geiger-mode avalanche photodiodes (also referred to as silicon photomultipliers SiPMs) are irradiated with 1 to 2.5 MeV γ's and electrons. We characterize radiation damage effects appearing in the reverse bias current, the dark current and count rate, the pixel gain, and the photon detection efficiency of the devices. An interesting observation on the dark current and count rate is made and linked to the specific damage caused by the irradiation.

  6. Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source

    Energy Technology Data Exchange (ETDEWEB)

    White, Shane A.; Landry, Guillaume; Reniers, Brigitte, E-mail: brigitte.reniers@maastro.nl [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC), Maastricht 6201 BN (Netherlands); Fonseca, Gabriel Paiva [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC), Maastricht 6201 BN, The Netherlands and Instituto de Pesquisas Energéticas e Nucleares – IPEN-CNEN/SP, São Paulo CP 11049, 05422-970 (Brazil); Holt, Randy; Rusch, Thomas [Xoft, A Subsidiary of iCAD, Sunnyvale, California 94085-4115 (United States); Beaulieu, Luc [Centre Hospitalier Universitaire de Québec Université Laval, Radio-Oncologie et Centre de Recherche en Cancérologie de l’Université Laval, Québec, Québec G1R 2J6 Canada (Canada); Verhaegen, Frank [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC), Maastricht 6201 BN, The Netherlands and Department of Oncology, McGill University, Montreal, Quebec H3G 1A4 (Canada)

    2014-06-15

    Purpose: The recently updated guidelines for dosimetry in brachytherapy in TG-186 have recommended the use of model-based dosimetry calculations as a replacement for TG-43. TG-186 highlights shortcomings in the water-based approach in TG-43, particularly for low energy brachytherapy sources. The Xoft Axxent is a low energy (<50 kV) brachytherapy system used in accelerated partial breast irradiation (APBI). Breast tissue is a heterogeneous tissue in terms of density and composition. Dosimetric calculations of seven APBI patients treated with Axxent were made using a model-based Monte Carlo platform for a number of tissue models and dose reporting methods and compared to TG-43 based plans. Methods: A model of the Axxent source, the S700, was created and validated against experimental data. CT scans of the patients were used to create realistic multi-tissue/heterogeneous models with breast tissue segmented using a published technique. Alternative water models were used to isolate the influence of tissue heterogeneity and backscatter on the dose distribution. Dose calculations were performed using Geant4 according to the original treatment parameters. The effect of the Axxent balloon applicator used in APBI which could not be modeled in the CT-based model, was modeled using a novel technique that utilizes CAD-based geometries. These techniques were validated experimentally. Results were calculated using two dose reporting methods, dose to water (D{sub w,m}) and dose to medium (D{sub m,m}), for the heterogeneous simulations. All results were compared against TG-43-based dose distributions and evaluated using dose ratio maps and DVH metrics. Changes in skin and PTV dose were highlighted. Results: All simulated heterogeneous models showed a reduced dose to the DVH metrics that is dependent on the method of dose reporting and patient geometry. Based on a prescription dose of 34 Gy, the average D{sub 90} to PTV was reduced by between ∼4% and ∼40%, depending on the

  7. Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, S., E-mail: smatsui@gpi.ac.jp; Mori, Y. [The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsucho, Nishiku, Hamamatsu, Shizuoka 431-1202 (Japan); Nonaka, T.; Hattori, T.; Kasamatsu, Y.; Haraguchi, D.; Watanabe, Y.; Uchiyama, K.; Ishikawa, M. [Hamamatsu Photonics K.K. Electron Tube Division, 314-5 Shimokanzo, Iwata, Shizuoka 438-0193 (Japan)

    2016-05-15

    For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.

  8. Low energy He+ irradiation effect on graphite surface

    International Nuclear Information System (INIS)

    Asari, E.; Nakamura, K.G.; Kitajima, M.; Kawabe, T.

    1992-01-01

    Study on the lattice disordering and the secondary electron emission under low energy (1-5keV) He + irradiation is reported. Real-time Raman measurements show that difference in the observed Raman spectra for different ion energies is due to the difference of the damage depth. The relation between the observed Raman spectrum and the depth profile of lattice damage is discussed. Energy dependence of the secondary electron emission coefficient are also described. (author)

  9. Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source

    International Nuclear Information System (INIS)

    White, Shane A.; Landry, Guillaume; Reniers, Brigitte; Fonseca, Gabriel Paiva; Holt, Randy; Rusch, Thomas; Beaulieu, Luc; Verhaegen, Frank

    2014-01-01

    Purpose: The recently updated guidelines for dosimetry in brachytherapy in TG-186 have recommended the use of model-based dosimetry calculations as a replacement for TG-43. TG-186 highlights shortcomings in the water-based approach in TG-43, particularly for low energy brachytherapy sources. The Xoft Axxent is a low energy ( w,m ) and dose to medium (D m,m ), for the heterogeneous simulations. All results were compared against TG-43-based dose distributions and evaluated using dose ratio maps and DVH metrics. Changes in skin and PTV dose were highlighted. Results: All simulated heterogeneous models showed a reduced dose to the DVH metrics that is dependent on the method of dose reporting and patient geometry. Based on a prescription dose of 34 Gy, the average D 90 to PTV was reduced by between ∼4% and ∼40%, depending on the scoring method, compared to the TG-43 result. Peak skin dose is also reduced by 10%–15% due to the absence of backscatter not accounted for in TG-43. The balloon applicator also contributed to the reduced dose. Other ROIs showed a difference depending on the method of dose reporting. Conclusions: TG-186-based calculations produce results that are different from TG-43 for the Axxent source. The differences depend strongly on the method of dose reporting. This study highlights the importance of backscatter to peak skin dose. Tissue heterogeneities, applicator, and patient geometries demonstrate the need for a more robust dose calculation method for low energy brachytherapy sources

  10. Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source.

    Science.gov (United States)

    White, Shane A; Landry, Guillaume; Fonseca, Gabriel Paiva; Holt, Randy; Rusch, Thomas; Beaulieu, Luc; Verhaegen, Frank; Reniers, Brigitte

    2014-06-01

    The recently updated guidelines for dosimetry in brachytherapy in TG-186 have recommended the use of model-based dosimetry calculations as a replacement for TG-43. TG-186 highlights shortcomings in the water-based approach in TG-43, particularly for low energy brachytherapy sources. The Xoft Axxent is a low energy (S700, was created and validated against experimental data. CT scans of the patients were used to create realistic multi-tissue/heterogeneous models with breast tissue segmented using a published technique. Alternative water models were used to isolate the influence of tissue heterogeneity and backscatter on the dose distribution. Dose calculations were performed using Geant4 according to the original treatment parameters. The effect of the Axxent balloon applicator used in APBI which could not be modeled in the CT-based model, was modeled using a novel technique that utilizes CAD-based geometries. These techniques were validated experimentally. Results were calculated using two dose reporting methods, dose to water (Dw,m) and dose to medium (Dm,m), for the heterogeneous simulations. All results were compared against TG-43-based dose distributions and evaluated using dose ratio maps and DVH metrics. Changes in skin and PTV dose were highlighted. All simulated heterogeneous models showed a reduced dose to the DVH metrics that is dependent on the method of dose reporting and patient geometry. Based on a prescription dose of 34 Gy, the average D90 to PTV was reduced by between ~4% and ~40%, depending on the scoring method, compared to the TG-43 result. Peak skin dose is also reduced by 10%-15% due to the absence of backscatter not accounted for in TG-43. The balloon applicator also contributed to the reduced dose. Other ROIs showed a difference depending on the method of dose reporting. TG-186-based calculations produce results that are different from TG-43 for the Axxent source. The differences depend strongly on the method of dose reporting. This study

  11. Low energy and low dose electron irradiation of potassium-lime-silicate glass investigated by XPS. I. Surface composition

    Czech Academy of Sciences Publication Activity Database

    Gedeon, O.; Zemek, Josef

    2003-01-01

    Roč. 320, - (2003), s. 177-186 ISSN 0022-3093 R&D Projects: GA ČR GA104/99/1407 Institutional research plan: CEZ:AV0Z1010914 Keywords : x-ray photoelectron spectroscopy * potassium-lime-silicate glass * electron -solid interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.563, year: 2003

  12. Low energy electron beam processing of YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chromik, Š., E-mail: stefan.chromik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Camerlingo, C. [CNR-SPIN, Istituto Superconduttori, Materiali Innovativi e Dispositivi, via Campi Flegrei 34, 80078 Pozzuoli (Italy); Sojková, M.; Štrbík, V.; Talacko, M. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Malka, I.; Bar, I.; Bareli, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Jung, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland)

    2017-02-15

    Highlights: • Improvement of superconducting properties of irradiated bridges under certain conditions. • 30 keV irradiation influence CuO{sub 2} planes as well as oxygen chains. • Direct confirmation of changes in oxygen chains using micro-Raman spectroscopy. • Possibility of electron writing. - Abstract: Effects of low energy 30 keV electron irradiation of superconducting YBa{sub 2}Cu{sub 3}O{sub 7−δ} thin films have been investigated by means of transport and micro-Raman spectroscopy measurements. The critical temperature and the critical current of 200 nm thick films initially increase with increasing fluency of the electron irradiation, reach the maximum at fluency 3 − 4 × 10{sup 20} electrons/cm{sup 2}, and then decrease with further fluency increase. In much thinner films (75 nm), the critical temperature increases while the critical current decreases after low energy electron irradiation with fluencies below 10{sup 20} electrons/cm{sup 2}. The Raman investigations suggest that critical temperature increase in irradiated films is due to healing of broken Cu−O chains that results in increased carrier’s concentration in superconducting CuO{sub 2} planes. Changes in the critical current are controlled by changes in the density of oxygen vacancies acting as effective pinning centers for flux vortices. The effects of low energy electron irradiation of YBCO turned out to result from a subtle balance of many processes involving oxygen removal, both by thermal activation and kick-off processes, and ordering of chains environment by incident electrons.

  13. Radiation degradation of marine polysaccharides by low energy electron beam

    International Nuclear Information System (INIS)

    Yoshii, Fumio; Nagasawa, Naotsugu; Kume, Tamikazu

    2003-01-01

    The radiation degradations of marine polysaccharides by both gamma Co-60 and electron beam irradiations are investigated. Polysaccharides and oligosaccharides can be produced by degradation of corresponding polysaccharides including marine polysaccharides such as alginates, chitin chitosan and carrageenan. The viscosity of alginate, chitosan and carrageenan solution decreases markedly with increase of the low energy electron beam irradiation time and the beam current. Furthermore, the viscosity is reduced sharply in short time for polysaccharide solution with low concentration, for instance carrageenan solution of 1%. (author)

  14. Development of real-time low energy electron calorimeter

    International Nuclear Information System (INIS)

    Noriah Mod Ali; Smith, F.A.

    1999-01-01

    A low energy electron beam calorimeter with a thin film window has been fabricated to facilitate a reliable method of dose assessment for electron beam energies down to 200 keV. The system was designed to incorporate a data-logger in order that it could be used on the self-shielded 200 keV facility at MINT. In use, the calorimeter started logging temperature a short time before it passed under the beam and it continued taking data until well after the end of the irradiation. Data could be retrieved at any time after the calorimeter had emerged from the irradiator

  15. Radiation processing of liquid with low energy electron accelerator

    International Nuclear Information System (INIS)

    Makuuchi, Keizo

    2003-01-01

    Radiation induced emulsion polymerization, radiation vulcanization of NR latex (RVNRL) and radiation degradation of natural polymers were selected and reviewed as the radiation processing of liquid. The characteristic of high dose rate emulsion polymerization is the occurrence of cationic polymerization. Thus, it can be used for the production of new materials that cannot be obtained by radical polymerization. A potential application will be production of polymer emulsion that can be used as water-borne UV/EB curing resins. The technology of RVNRL by γ-ray has been commercialized. RVNRL with low energy electron accelerator is under development for further vulcanization cost reduction. Vessel type irradiator will be favorable for industrial application. Radiation degradation of polysaccharides is an emerging and promising area of radiation processing. However, strict cost comparison between liquid irradiation with low energy EB and state irradiation with γ-ray should be carried out. (author)

  16. Radiation processing of liquid with low energy electron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, Keizo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2003-02-01

    Radiation induced emulsion polymerization, radiation vulcanization of NR latex (RVNRL) and radiation degradation of natural polymers were selected and reviewed as the radiation processing of liquid. The characteristic of high dose rate emulsion polymerization is the occurrence of cationic polymerization. Thus, it can be used for the production of new materials that cannot be obtained by radical polymerization. A potential application will be production of polymer emulsion that can be used as water-borne UV/EB curing resins. The technology of RVNRL by {gamma}-ray has been commercialized. RVNRL with low energy electron accelerator is under development for further vulcanization cost reduction. Vessel type irradiator will be favorable for industrial application. Radiation degradation of polysaccharides is an emerging and promising area of radiation processing. However, strict cost comparison between liquid irradiation with low energy EB and state irradiation with {gamma}-ray should be carried out. (author)

  17. Evidence for CO formation in irradiated methanol and acetone: contribution of low-energy electron-energy-loss spectroscopy to γ-radiolysis

    International Nuclear Information System (INIS)

    Jay-Gerin, J.-P.; Fraser, M.-J.; Michaud, M.; Sanche, L.; Swiderek, P.; Ferradini, C.

    1997-01-01

    Energy-loss spectra for low-energy electrons incident on acetone condensed on a multilayer film of argon, and on a methanol film deposited on a metallic substrate, are reported. In both cases, the formation of carbon monoxide has been detected. These results are directly related to those obtained in the liquid-phase γ-radiolysis of the two compounds. (author)

  18. Low energy electron scattering from fuels

    International Nuclear Information System (INIS)

    Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M.

    2011-01-01

    Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

  19. Low energy electron scattering from fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M. [Universidade Federal de Juiz de Fora (UFJF), MG (Brazil). Dept. de Fisica; Yates, Brent; Hong, Ling; Khakoo, Murtadha A. [California State University at Fullerton, CA (US). Physics Department; Bettega, Marcio H.F. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Fisica; Costa, Romarly F. da [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas; Lima, Marco A.P. [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol (CTBE/CNPEM), Campinas, SP (Brazil)

    2011-07-01

    Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

  20. Radiation processing of natural polymers using low energy electron beam

    International Nuclear Information System (INIS)

    Kume, Tamikazu

    2004-01-01

    Radiation processing is widely used in Japan and the economic scale of radiation application amounted to about 71 b$ (ratio relative to GDP: 1.7%) in total. It consisted of 60 b$ (85%) in industry, 10 b$ (14%) in medicine and 1 b$ (1%) in agriculture. Irradiation using gamma-ray from 60 Co and electron beam is commercially used for the sterilization and modification of materials. Utilization of natural polymers by radiation has been investigated for recycling the natural resources and reducing the environmental pollution. Polysaccharides such as chitosan, sodium alginate, carrageenan, cellulose, pectin were easily degraded by irradiation and induced various kinds of biological activities, i.e. anti-bacterial activity, elicitor activity, plant growth promotion, suppression of environmental stress on plants. Radiation degraded chitosan was effective to enhance the growth of plants in tissue culture. Low energy electron beam (EB) irradiation has a variety of applications and good safety. A self-shielded low energy electron accelerator system needs an initial investment much lower than a 60 Co facility. It was demonstrated that the liquid sample irradiation system using low energy EB was effective not only for the preparation of degraded polysaccharides but also for radiation vulcanization of natural rubber latex (RVNRL). Some carbohydrate derivatives, carboxymethylcellulose (CMC), carboxymethyl-starch and carboxymethyl-chitin/chitosan, can be crosslinked under certain radiation condition and produced the biodegradable hydrogel for medical and agricultural use. Treatment of soybean seeds by low energy EB enhanced the growth and the number of rhizobia on the root. (author)

  1. New development for low energy electron beam processor

    International Nuclear Information System (INIS)

    Takei, Taro; Goto, Hitoshi; Oizumi, Matsutoshi; Hirakawa, Tetsuya; Ochi, Masafumi

    2003-01-01

    Newly developed low-energy electron beam (EB) processors that have unique designs and configurations compared to conventional ones enable electron-beam treatment of small three-dimensional objects, such as grain-like agricultural products and small plastic parts. As the EB processor can irradiate the products from the whole angles, the uniform EB treatment can be achieved at one time regardless the complex shapes of the product. Here presented are two new EB processors: the first system has cylindrical process zone, which allows three-dimensional objects to be irradiated with one-pass treatment. The second is a tube-type small EB processor, achieving not only its compactor design, but also higher beam extraction efficiency and flexible installation of the irradiation heads. The basic design of each processor and potential applications with them will be presented in this paper. (author)

  2. Low-energy electron microdosimetry of CS-137

    International Nuclear Information System (INIS)

    Paschoa, A.S.; Wrenn, M.E.

    1980-09-01

    The mass of tissue irradiated by an internal emitter depends upon the distribution of the radionuclide within the organism and the type of radiation emitted. The range (95% absorption) of low-energy electron effectively defines the sensitive volume in which the energy of the emitted electron is deposited. Accordingly, in the case of Auger electron microdosimetry of internal emitters the correct definition of the sensitive volume is of paramount importance. The amount of energy delivered by the monoenergetic electrons emitted by the decay system 137 Cs → sup(137m)Ba to spherical volumes of water-like tissue media of radii equivalent to the estimated ranges of those electrons in water is calculated and discussed as far as the variations of the estimated ranges of electrons as a function of the initial energy of emission are concerned. Although there are still many uncertainties on the actual ranges of low-energy electrons, one can state confidently that the ranges of the Auger electrons of the decay system 137 Cs → 137 sup(m) Ba → 137 Ba can be considered to be in the same order of magnitude of the diameter of a cell. The energy deposition in spherical volumes of water-like tissue media, considered equivalent to the sensitive volumes for the Auger electrons of the decay system 137 Cs → 137 sub(m) Ba → 137 Ba, range for several orders of magnitude from 10 2 to about 10 10 times higher than the energy deposition in similar media by the internal conversion electrons of this decay system. If equivalent variations of energy deposition per unit mass occur when the masses considered are cellular, and subcellular structures, then the effects into the sensitive volume should be taken into biological consideration as far as the microdosimetry of low-energy electrons (approximately equal to 10 keV) is considered, whenever there is internal localization of Auger emitters. (Author) [pt

  3. Low energy intense electron beams with extra-low energy spread

    International Nuclear Information System (INIS)

    Aleksandrov, A.V.; Calabrese, R.; Ciullo, G.; Dikansky, N.S.; Guidi, V.; Kot, N.C.; Kudelainen, V.I.; Lamanna, G.; Lebedev, V.A.; Logachov, P.V.; Tecchio, L.; Yang, B.

    1994-01-01

    Maximum achievable intensity for low energy electron beams is a feature that is not very often compatible with low energy spread. We show that a proper choice of the source and the acceleration optics allows one to match them together. In this scheme, a GaAs photocathode excited by a single-mode infrared laser and adiabatic acceleration in fully magnetised optics enables the production of a low-energy-spread electron beam with relatively high intensity. The technological problems associated with the method are discussed together with its limitations. (orig.)

  4. The effects of illumination on deep levels observed in as-grown and low-energy electron irradiated high-purity semi-insulating 4H-SiC

    Science.gov (United States)

    Alfieri, G.; Knoll, L.; Kranz, L.; Sundaramoorthy, V.

    2018-05-01

    High-purity semi-insulating 4H-SiC can find a variety of applications, ranging from power electronics to quantum computing applications. However, data on the electronic properties of deep levels in this material are scarce. For this reason, we present a deep level transient spectroscopy study on HPSI 4H-SiC substrates, both as-grown and irradiated with low-energy electrons (to displace only C-atoms). Our investigation reveals the presence of four deep levels with activation energies in the 0.4-0.9 eV range. The concentrations of three of these levels increase by at least one order of magnitude after irradiation. Furthermore, we analyzed the behavior of these traps under sub- and above-band gap illumination. The nature of the traps is discussed in the light of the present data and results reported in the literature.

  5. Low energy electron irradiation induced deep level defects in 6H-SiC: The implication for the microstructure of the deep levels E1/E2

    International Nuclear Information System (INIS)

    Chen, X.D.; Fung, S.; Beling, C.D.; Lui, M.K.; Ling, C.C.; Yang, C.L.; Ge, W.K.; Wang, J.N.; Gong, M.

    2004-01-01

    N-type 6H-SiC samples irradiated with electrons having energies of E e =0.2, 0.3, 0.5, and 1.7 were studied by deep level transient technique. No deep level was detected at below 0.2 MeV irradiation energy while for E e ≥0.3 MeV, deep levels ED1, E 1 /E 2 , and E i appeared. By considering the minimum energy required to displace the C atom or the Si atom in the SiC lattice, it is concluded that generation of the deep levels E 1 /E 2 , as well as ED1 and E i , involves the displacement of the C atom in the SiC lattice

  6. Application of low energy electron beam to precoated steel plates

    International Nuclear Information System (INIS)

    Koshiishi, Kenji

    1989-01-01

    Recently in the fields of home electric appliances, machinery and equipment and interior building materials, the needs for the precoated steel plates having the design and function of high class increase rapidly. In order to cope with such needs, the authors have advanced the examination on the application of electron beam hardening technology to precoated steel plates, and developed the precoated steel plates of high grade and high design 'Super Tecstar EB Series' by utilizing low energy electron beam. The features of this process are (1) hardening can be done at room temperature in a short time-thermally weak films can be adhered, (2) high energy irradiation-the hardening of thick enamel coating and the adhesion of colored films are feasible, (3) the use of monomers of low molecular weight-by high crosslinking, the performance of high sharpness, high hardness, anti-contamination property and so on can be given. The application to precoated steel plate production process is the coating and curing of electron beam hardening type paints, the coating of films with electron beam hardening type adhesives, and the reforming of surface polymer layers by impregnating monomers and causing graft polymerization with electron beam irradiation. The outline of the Super Tecstar EB Series is described. (K.I.)

  7. A real-time low energy electron calorimeter

    International Nuclear Information System (INIS)

    Mod Ali, N.; Smith, F.A.

    1999-01-01

    A real-time low energy electron calorimeter with a thin film window has been designed and fabricated to facilitate a reliable method of dose assessment for electron beam energies down to 200 keV. The work was initiated by the Radiation Physics Group of Queen Mary and Westfield College in collaboration with the National Physical Laboratory (NPL), Teddington. Irradiations were performed on the low and medium electron energy electron accelerators at the Malaysian Institute for Nuclear Technology Research (MINT). Calorimeter response was initially tested using the on-line temperature measurements for a 500-keV electron beam. The system was later redesigned by incorporating a data-logger to use on the self-shielded 200-keV beam. In use, the final version of the calorimeter could start logging temperature a short time before the calorimeter passed under the beam and continue measurements throughout the irradiation. Data could be easily retrieved at the end of the exposure. (author)

  8. Radiation from silver films bombarded by low-energy electrons

    International Nuclear Information System (INIS)

    Chung, M.S.; Callcott, T.A.; Kretschmann, E.; Arakawa, E.T.

    1980-01-01

    Emission spectra from Ag films irradiated by low energy electrons (20-1500 eV) have been measured, and the results compared with theory. For relatively smooth films, two peaks in the spectra are resolved. One at 3.73 eV, the volume plasmon energy, is attributed to transition radiation and/or bremsstrahlung. The second, at about 3.60 eV, is very sensitive to surface roughness in both position and magnitude and is produced by roughness-coupled radiation from surface plasmons. For rough films, the roughness-coupled radiation dominates the emission. In addition to spectral shapes, the polarization of the radiation and its intensity as a function of electron energy were measured. The experimental results are compared with new calculations of roughness-coupled emission which account for most of our observations. They indicate that high wavevector roughness components play the dominant role in the emission process. (orig.)

  9. Reactions induced by low energy electrons in cryogenic films

    International Nuclear Information System (INIS)

    Bass, A.D.; Sanche, L.

    2003-01-01

    We review recent research on reactions (including dissociation) initiated by low-energy electron bombardment of monolayer and multilayer molecular solids at cryogenic temperatures. With incident electrons of energies below 20 eV, dissociation is observed by the electron stimulated desorption (ESD) of anions from target films and is attributed to the processes of dissociative electron attachment (DEA) and to dipolar dissociation. It is shown that DEA to condensed molecules is sensitive to environmental factors such as the identity of co-adsorbed species and film morphology. The effects of image-charge induced polarization on cross-sections for DEA to CH3Cl are also discussed. Taking as examples, the electron-induced production of CO within multilayer films of methanol and acetone, it is shown that the detection of electronic excited states by high resolution electron energy loss spectroscopy can be used to monitor electron beam damage. In particular, the incident energy dependence of the CO indicates that below 19 eV, dissociation proceeds via the decay of transient negative ions (TNI) into electronically excited dissociative states. The electron induced dissociation of biomolecular targets is also considered, taking as examples the ribose analog tetrahydrofuran and DNA bases adenine and thymine, cytosine and guanine. The ESD of anions from such films also show dissociation via the formation of TNI. In multilayer molecular solids, fragment species resulting from dissociation, may react with neighboring molecules, as is demonstrated in anion ESD measurements from films containing O 2 and various hydrocarbon molecules. X-ray photoelectron spectroscopy measurements reported for electron irradiated monolayers of H 2 O and CF 4 on a Si - H passivated surface further show that DEA is an important initial step in the electron-induced chemisorption of fragment species

  10. Degradation of carrageenan by low energy electron accelerator

    International Nuclear Information System (INIS)

    Relleve, L.; Aranilla, C.; Abad, L.; Dela Rosa, A.; Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio

    2004-01-01

    Degradation of κ-carrageenan using vessel-type low energy electron accelerator was investigated. Carrageenan with different molecular weights were obtained from irradiation of high molecular weight (HMW) and low molecular weight (LMW) κ-carrageenan. Other results presented were obtained from degradation studies of carrageenan by gamma rays. The decrease in molecular weight was accompanied by partial desulfation. From comparison of radiation degradation yield (Gd), it was found that the susceptibility to radiation of the three types of carrageenans in aqueous/gel forms follows the order of λ->ι->>κ- and could have been influenced by their conformational state. κ-carrageenan with molecular weight of ca. 10,000 showed strong growth promotion effect for potato in tissue culture. (author)

  11. Low Energy Electron Cooler for NICA Booster

    CERN Document Server

    Denisov, A P

    2017-01-01

    BINP has developed an electron cooler to increase the ion accumulation efficiency in the NICA (Nuclotron-based Ion Collider fAcility) heavy ion booster (JINR, Dubna). Adjustment of the cooler magnetic system provides highly homogeneous magnetic field in the cooling section B trans/B long ≤ 4∙10-5 which is vital for efficient electron cooling. First experiments with an electron beam performed at BINP demonstrated the target DC current of 500 mA and electron energy 6 keV.

  12. Tuning the electronic properties of LaAlO3/SrTiO3 interfaces by irradiating the LaAlO3 surface with low-energy cluster ion beams

    Science.gov (United States)

    Ridier, Karl; Aureau, Damien; Bérini, Bruno; Dumont, Yves; Keller, Niels; Vigneron, Jackie; Etcheberry, Arnaud; Domengès, Bernadette; Fouchet, Arnaud

    2018-01-01

    We have investigated the effects of low-energy ion beam irradiations using argon clusters on the chemical and electronic properties of LaAlO3/SrTiO3 (LAO/STO) heterointerfaces by combining x-ray photoelectron spectroscopy (XPS) and electrical transport measurements. Due to its unique features, we demonstrate that a short-time cluster ion irradiation of the LAO surface induces significant modifications in the chemical properties of the buried STO substrate with (1) a lowering of Ti atoms oxidation states (from Ti4 + to Ti3 + and Ti2 +) correlated to the formation of oxygen vacancies at the LAO surface and (2) the creation of new surface states for Sr atoms. Contrary to what is generally observed by using higher energy ion beam techniques, this leads to an increase of the electrical conductivity at the LAO/STO interface. Our XPS data clearly reveal the existence of dynamical processes on the titanium and strontium atoms, which compete with the effect of the cluster ion beam irradiation. These relaxation effects are in part attributed to the diffusion of the ion-induced oxygen vacancies in the entire heterostructure since an increase of the interfacial metallicity is also evidenced far from the irradiated area. This paper highlights the possibility of tuning the electrical properties of LAO/STO interfaces by surface engineering, confirming experimentally the intimate connection between LAO chemistry and electronic properties of LAO/STO interfaces.

  13. Low energy electron transport in furfural

    OpenAIRE

    Lozano, Ana I.; Krupa, K.; Ferreira da Silva, F.; Limao-Vieira, Paulo; Blanco, Francisco; Muñoz, Antonio; Jones, D. B.; Brunger, M. J.; García, Gustavo

    2017-01-01

    We report on an initial investigation into the transport of electrons through a gas cell containing 1 mTorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulat...

  14. Low energy electron transport in furfural

    Science.gov (United States)

    Lozano, Ana I.; Krupa, Kateryna; Ferreira da Silva, Filipe; Limão-Vieira, Paulo; Blanco, Francisco; Muñoz, Antonio; Jones, Darryl B.; Brunger, Michael J.; García, Gustavo

    2017-09-01

    We report on an initial investigation into the transport of electrons through a gas cell containing 1 mTorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulation, our preferred energy loss distribution function is presented and discussed.

  15. Electron-ion recombination at low energy

    International Nuclear Information System (INIS)

    Andersen, L.H.

    1993-01-01

    The work is based on results obtained with a merged-beams experiment. A beam of electronics with a well characterized density and energy distribution was merged with a fast, monoenergetic ion beam. Results have been obtained for radiative recombination and dielectronic recombination at low relative energies (0 to ∼70eV). The obtained energy resolution was improved by about a factor of 30. High vacuum technology was used to suppress interactions with electrons from the environments. The velocity distribution of the electron beam was determined. State-selective dielectronic-recombination measurements were performable. Recombination processes were studied. The theoretical background for radiative recombination and Kramers' theory are reviewed. The quantum mechanical result and its relation to the semiclassical theory is discussed. Radiative recombination was also measured with several different non-bare ions, and the applicability of the semiclassical theory to non-bare ions was investigated. The use of an effective charge is discussed. For dielectronic recombination, the standard theoretical approach in the isolated resonance and independent-processes approximation is debated. The applicability of this method was tested. The theory was able to reproduce most of the experimental data except when the recombination process was sensitive to couplings between different electronic configurations. The influence of external perturbing electrostatic fields is discussed. (AB) (31 refs.)

  16. Scanning transmission low-energy electron microscopy

    Czech Academy of Sciences Publication Activity Database

    Müllerová, Ilona; Hovorka, Miloš; Konvalina, Ivo; Unčovský, M.; Frank, Luděk

    2011-01-01

    Roč. 55, č. 4 (2011), 2:1-6 ISSN 0018-8646 R&D Projects: GA AV ČR IAA100650902; GA MŠk ED0017/01/01 Institutional research plan: CEZ:AV0Z20650511 Keywords : TEM * STEM * SEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.723, year: 2011

  17. Low energy electron transport in furfural

    International Nuclear Information System (INIS)

    Lozano, A.I.; Garcia, G.; Krupa, K.; Ferreira da Silva, F.; Limao-Vieira, P.; Blanco, F.; Munoz, A.; Jones, D.B.; Brunger, M.J.

    2017-01-01

    The cyclic configuration of the furfural molecule is similar to the 5-membered ring structure constituting the sugar units of the DNA helix, hence its importance in biology. In this paper, we report on an initial investigation into the transport of electrons through a gas cell containing 1 mtorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulation, our preferred energy loss distribution function is presented and discussed

  18. Scattering of polarized low-energy electrons by ferromagnetic metals

    International Nuclear Information System (INIS)

    Helman, J.S.

    1981-01-01

    A source of spin polarized electrons with remarkable characteristics based on negative electron affinity (NEA) GaAs has recently been developed. It constitutes a unique tool to investigate spin dependent interactions in electron scattering processes. The characteristics and working principles of the source are briefly described. Some theoretical aspects of the scattering of polarized low-energy electrons by ferromagnetic metals are discussed. Finally, the results of the first polarized low-energy electron diffraction experiment using the NEA GaAs source are reviewed; they give information about the surface magnetization of ferromagnetic Ni (110). (Author) [pt

  19. A comparison of the microbicidal effectiveness of gamma rays and high and low energy electron radiations

    International Nuclear Information System (INIS)

    Tallentire, Alan; Miller, Arne; Helt-Hansen, Jakob

    2010-01-01

    The radiation response of spores of Bacillus pumilus were examined for irradiation with cobalt 60 photons, 10 MeV electrons and low energy electrons at 100 and 80 keV. The responses were found to be the same for all types of radiation within the measurement uncertainties and were also in agreement with a previously published value.

  20. A comparison of the microbicidal effectiveness of gamma rays and high and low energy electron radiations

    DEFF Research Database (Denmark)

    Tallentire, A.; Miller, Arne; Helt-Hansen, Jakob

    2010-01-01

    The radiation response of spores of Bacillus pumilus were examined for irradiation with cobalt 60 photons, 10 MeV electrons and low energy electrons at 100 and 80 keV. The responses were found to be the same for all types of radiation within the measurement uncertainties and were also in agreement...... with a previously published value....

  1. Design, development and characterization of tetrode type electron gun system for generation of low energy electrons

    International Nuclear Information System (INIS)

    Deore, A.V.; Bhoraskar, V.N.; Dhole, S.D.

    2011-01-01

    A tetrode type electron gun system for the generation of low energy electrons was designed, developed and characterized. An electron gun having four electrodes namely cathode, focusing electrode, control electrode and anode has been designed for the irradiation experiments. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum upto 100 μA. The electron gun and a faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the faraday cup and irradiated with low energy electrons at a pressure around 10 -6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi electrode assembly and found to be well within 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric materials. (author)

  2. Electron polarimetry at low energies in Hall C at JLab

    International Nuclear Information System (INIS)

    Gaskell, D.

    2013-01-01

    Although the majority of Jefferson Lab experiments require multi-GeV electron beams, there have been a few opportunities to make electron beam polarization measurements at rather low energies. This proceedings will discuss some of the practical difficulties encountered in performing electron polarimetry via Mo/ller scattering at energies on the order of a few hundred MeV. Prospects for Compton polarimetry at very low energies will also be discussed. While Mo/ller scattering is likely the preferred method for electron polarimetry at energies below 500 MeV, there are certain aspects of the polarimeter and experiment design that must be carefully considered

  3. Standard Test Method for Application of Ionization Chambers to Assess the Low Energy Gamma Component of Cobalt-60 Irradiators Used in Radiation-Hardness Testing of Silicon Electronic Devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 Low energy components in the photon energy spectrum of Co-60 irradiators lead to absorbed dose enhancement effects in the radiation-hardness testing of silicon electronic devices. These low energy components may lead to errors in determining the absorbed dose in a specific device under test. This method covers procedures for the use of a specialized ionization chamber to determine a figure of merit for the relative importance of such effects. It also gives the design and instructions for assembling this chamber. 1.2 This method is applicable to measurements in Co-60 radiation fields where the range of exposure rates is 7 × 10 −6 to 3 × 10−2 C kg −1 s−1 (approximately 100 R/h to 100 R/s). For guidance in applying this method to radiation fields where the exposure rate is >100 R/s, see Appendix X1. Note 1—See Terminology E170 for definition of exposure and its units. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information onl...

  4. Very low energy scanning electron microscopy in nanotechnology

    Czech Academy of Sciences Publication Activity Database

    Müllerová, Ilona; Hovorka, Miloš; Mika, Filip; Mikmeková, Eliška; Mikmeková, Šárka; Pokorná, Zuzana; Frank, Luděk

    2012-01-01

    Roč. 9, 8/9 (2012), s. 695-716 ISSN 1475-7435 R&D Projects: GA MŠk OE08012; GA MŠk ED0017/01/01; GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : scanning electron microscopy * very low energy electrons * cathode lens * grain contrast * strain contrast * imaging of participates * dopant contrast * very low energy STEM * graphene Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.087, year: 2012

  5. Ultra-low-energy wide electron exposure unit

    International Nuclear Information System (INIS)

    Yonago, Akinobu; Oono, Yukihiko; Tokunaga, Kazutoshi; Kishimoto, Junichi; Wakamoto, Ikuo

    2001-01-01

    Heat and ultraviolet ray processes are used in surface dryness of paint, surface treatment of construction materials and surface sterilization of food containers. A process using a low-energy wide-area electron beam (EB) has been developed that features high speed and low drive cost. EB processing is not widespread in general industry, however, due to high equipment cost and difficult maintenance. We developed an ultra-low-energy wide-area electron beam exposure unit, the Mitsubishi Wide Electron Exposure Unit (MIWEL) to solve these problems. (author)

  6. Low energy ion implantation and high energy heavy ion irradiation in C60 films

    International Nuclear Information System (INIS)

    Narayanan, K.L.; Yamaguchi, M.; Dharmarasu, N.; Kojima, N.; Kanjilal, D.

    2001-01-01

    C 60 films have been bombarded with low energy boron ions and high energy swift heavy ions (SHI) of silver and oxygen at different doses. Raman scattering and Fourier transform infrared (FTIR) studies were carried out on the virgin and irradiated films and the results are in good agreement with each other. The films subject to low energy boron ion implantation showed destruction of the bukky balls whereas the films subject to high energy ion irradiation did not show appreciable effects on their structure. These results indicate that C 60 films are more prone to defects by elastic collision and subsequent implantation at lower energy. Irradiation at higher energy was less effective in creating appreciable defects through electronic excitation by inelastic collisions at similar energy density

  7. Charge-coupled device area detector for low energy electrons

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav

    2003-01-01

    Roč. 74, č. 7 (2003), s. 3379 - 3384 ISSN 0034-6748 R&D Projects: GA ČR GA102/00/P001 Institutional research plan: CEZ:AV0Z2065902 Keywords : low energy electrons * charged-coupled device * detector Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.343, year: 2003

  8. Utilization of low-energy electron accelerators in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2003-02-01

    There are more than 20 electron accelerators in Korea. Most of those are installed in factories for heat-resistant cables, heat-shrinkable cables, radial tires, foams, tube/ films, curing, etc. Four low-energy electron accelerators are in operation for research purposes such as polymer modification, purification of flue gas, waste water treatment, modification of semiconductor characteristics, etc. (author)

  9. Utilization of low-energy electron accelerators in Korea

    International Nuclear Information System (INIS)

    Lee, Byung Cheol

    2003-01-01

    There are more than 20 electron accelerators in Korea. Most of those are installed in factories for heat-resistant cables, heat-shrinkable cables, radial tires, foams, tube/ films, curing, etc. Four low-energy electron accelerators are in operation for research purposes such as polymer modification, purification of flue gas, waste water treatment, modification of semiconductor characteristics, etc. (author)

  10. Low Energy Electrons as Probing Tool for Astrochemical Reaction Mechanisms

    Science.gov (United States)

    Hendrik Bredehöft, Jan; Swiderek, Petra; Hamann, Thorben

    ionized and the reaction barrier is drastically lowered so that instant reaction between ethylene and ammonia occurs. This hydroamination reaction by means of low energy electrons or an analogous reaction mechanism could also help in clarifying the formation of the intermediate molecules observed in interstellar dust clouds. The formation for example of formamide from CO and NH3 could be facilitated by a very similar process. Formamide is a very interesting molecule in Astrochemistry as well as Astrobiology, since it is the smallest molecule with a peptide bond, the kind of bond that forms proteins from amino acids. Such ionisation-driven reactions leading to the formation of larger molecules appear to be more generally relevant than previously thought as will be discussed in this contribution. [1] Cazaux S., Caselli P., Tielens A.G.G.M., Le Bourlot J., Walmsley M: Molecular Hydrogen formation on grain surfaces. J of Phys. Conf. Series 6 (2005), 155-160 [2] Muñoz Caro G.M., Meierhenrich U.J., Schutte U.W., Barbier B., Arcones Segovia A., Rosen-n bauer H., Thiemann W.H.-P., Brack A. and Greenberg J.M.: Amino acids from ultraviolet irradiation of interstellar ice analogues. Nature 416 (2002), 403-406 [3] Bredehüft, J.H., Meierhenrich U.: Amino acid structures from UV irradiation of simulated interstellar ices. in Takenaka N. (ed): Recent Developments of Chemistry and Photochemistry in Ice. Transworld Research Network, Kerala, India (2008) [4] Cooper G., Kimmich N., Belisle W., Sarinana J., Brabham K. and Garrel L.: Carbonaceous meteorites as a source of sugar-related organic compounds for the early Earth. Nature 414 (2001), 879-883 [5] Meierhenrich U.J., Muñoz Caro G.M., Schutte W.A., Thiemann W.H.-P. Barbier B., Brack n A.: Precursors of biological cofactors from ultraviolet irradiation of circumstellar/interstellar ice analogs. Chemistry -A European Journal 11 (2005), 4895-4900 [6] Matthews C.N. and Minard R.D.: Hydrogen cyanide polymers, comets and the origin of life

  11. Utilization of bio-resources by low energy electron beam

    International Nuclear Information System (INIS)

    Kume, Tamikazu

    2003-01-01

    Utilization of bio-resources by radiation has been investigated for recycling the natural resources and reducing the environmental pollution. Polysaccharides such as chitosan and sodium alginate were easily degraded by irradiation and induced various kinds of biological activities, i.g. anti-microbial activity, promotion of plant growth, suppression of heavy metal stress, phytoalexins induction. Radiation degraded chitosan was effective to enhance the growth of plants in tissue culture. It was demonstrated that the liquid sample irradiation system using low energy EB was effective for the preparation of degraded polysaccharides. Methylcellulose (MC) can be crosslinked under certain radiation condition as same as carboxymethylcellulose (CMC) and produced the biodegradable hydrogel for medical and agricultural use. Treatment of soybean seeds by low energy EB enhanced the growth and the number of rhizobia on the root. (author)

  12. The interaction of low-energy electrons with fructose molecules

    Science.gov (United States)

    Chernyshova, I. V.; Kontrosh, E. E.; Markush, P. P.; Shpenik, O. B.

    2017-11-01

    Using a hypocycloidal electronic spectrometer, the interactions of low energy electrons (0-8.50 eV) with fructose molecules, namely, electron scattering and dissociative attachment, are studied. The results of these studies showed that the fragmentation of fructose molecules occurs effectively even at an electron energy close to zero. In the total electron-scattering cross section by molecules, resonance features (at energies 3.10 and 5.00 eV) were first observed near the formation thresholds of light ion fragments OH- and H-. The correlation of the features observed in the cross sections of electron scattering and dissociative attachment is analyzed.

  13. Radiation vulcanization of natural rubber latex (NRL) using low energy electron beam accelerator

    International Nuclear Information System (INIS)

    Feroza Akhtar; Keizo Makuuchi; Fumio Yoshii

    1996-01-01

    The electron beam induced vulcanization of natural rubber latex has been studied using low energy Electron Beam (EB) accelerators of 300, 250 and 175 keV ne latex was irradiated in a special type stainless steel reaction reactor with a stirrer at the bottom of the reactor. From the results it was found that 300 and 250 keV accelerators could effectively vulcanize NRL. But accelerator of 175 keV is too low energy to vulcanize the latex. At the same time a drum type irradiator where thin layer of NRL was irradiated by accelerator, was used for vulcanization of NRL. This type of irradiator also showed good physical properties of vulcanized latex. The effects of beam current and stirrer speed on vulcanization were studied

  14. Low Energy Electrons in the Mars Plasma Environment

    Science.gov (United States)

    Link, Richard

    2001-01-01

    The ionosphere of Mars is rather poorly understood. The only direct measurements were performed by the Viking 1 and 2 landers in 1976, both of which carried a Retarding Potential Analyzer. The RPA was designed to measure ion properties during the descent, although electron fluxes were estimated from changes in the ion currents. Using these derived low-energy electron fluxes, Mantas and Hanson studied the photoelectron and the solar wind electron interactions with the atmosphere and ionosphere of Mars. Unanswered questions remain regarding the origin of the low-energy electron fluxes in the vicinity of the Mars plasma boundary. Crider, in an analysis of Mars Global Surveyor Magnetometer/Electron Reflectometer measurements, has attributed the formation of the magnetic pile-up boundary to electron impact ionization of exospheric neutral species by solar wind electrons. However, the role of photoelectrons escaping from the lower ionosphere was not determined. In the proposed work, we will examine the role of solar wind and ionospheric photoelectrons in producing ionization in the upper ionosphere of Mars. Low-energy (internal (photoelectron) sources of ionization, and accounts for Auger electron production. The code will be used to analyze Mars Global Surveyor measurements of solar wind and photoelectrons down to altitudes below 200 km in the Mars ionosphere, in order to determine the relative roles of solar wind and escaping photoelectrons in maintaining plasma densities in the region of the Mars plasma boundary.

  15. Argon defect complexes in low energy Ar irradiated molybdenum

    International Nuclear Information System (INIS)

    Veen, A. van; Buters, W.T.M.; Kolk, G.J. van der; Caspers, L.M.; Armstrong, T.R.

    1982-01-01

    Thermal desorption spectrometry has been used to study the defects created in Mo irradiated along the direction with Ar ions ranging in energy from 0.1 to 2 keV. In addition to monitoring the release of the implanted Ar, additional information has been obtained by decoration of the defects with low energy helium and subsequent monitoring of the helium release. The studies show evidence that the Ar can be trapped in both substitutional sites and in a configuration in which the Ar is associated with vacancies (ArVsub(n), n >= 2). Most of the Ar implanted at high energy is released at approx. equal to 1500 K by thermal vacancy assisted diffusion. Argon trapped closer to the surface is released at lower temperatures via at least three different surface related release mechanisms. Additional results are presented on the interaction of self interstitial atoms (introduced by 100 eV Xe bombardment) with the Ar defects. Substitutional Ar is found to convert to interstitial Ar which seems to be mobile at room temperature. The Ar-vacancy complexes are found to be reduced to substitutional Ar. The results of atomistic calculations of the release mechanisms will also be presented. (orig.)

  16. Immobilization of enzyme and antibody by low energy electron beam polymerization

    International Nuclear Information System (INIS)

    Kaetsu, Isao; Kumakura, Minoru

    1987-01-01

    Immobilization of glucoamylase and AFP-antibody was studied using an electron beam of relatively low energy. A thin polymer membrane formed by irradiation of monomer enzyme mixture in a buffer, which had a considerable enzymatic activity. A membrane of almost the same thickness and activity was obtained by repeated irradiation. The effect of irradiation conditions on the immobilization and the variations of irradiation method for immobilization were investigated. The immobilization of antibody was carried out in similar ways as for enzyme, and the product also showed a considerable activity. (author)

  17. Low Energy Electron Gun on Board a Scientific Satellite GEOTAIL

    OpenAIRE

    TSUTSUI, Minoru; ONISHI, Yoshiaki; MATSUMOTO, Hiroshi; KIMURA, Iwane; 筒井, 稔; 大西, 嘉昭; 松本, 紘; 木村, 磐根

    1988-01-01

    A low energy electron gun to be used for beam-plasma interaction experiments by a scientific satellite GEOTAIL has been designed and manufactured. Electrodes of the gun have been modified from the Pierce type gun because of the use of a directly heated cathode. Spatial density distributions of beam electrons emitted from the new gun have been measured in a large vacuum chamber, and characteristic curves of emission currents for some beam energies and cathode powers have been checked repeatedl...

  18. Elastic scattering of low energy electrons by hydrogen molecule

    International Nuclear Information System (INIS)

    Freitas, L.C.G.; Mu-Tao, L.; Botelho, L.F.

    1987-01-01

    The coherent version of the Renormalized Multiple-Centre Potential Model (RMPM) has been extended to treat the elastic scattering of low energy electrons by H2 molecule. The intramolecular Multiple Scattering (MS) effect has also been included. The comparison against the experimental data shows that the inclusion of the MS improves significantly with experiment. The extension of the present method to study electron-polyatomic molecule interaction is also discussed. (author) [pt

  19. Development of the techniques for food processing with low-energy electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Todoroki, Setsuko; Hayashi, Toru [National Food Research Inst., Tsukuba, Ibaraki (Japan)

    1999-02-01

    This study aimed to construct a new electron beam irradiation apparatus which allows to perform homogeneous irradiation up to a certain depth of a spherical or granular material through rotating it. And the sterilizing effects of this apparatus on various kinds of spices such as black and white peppers (grains), turmeric (root), coriander (seed), basil (leaves) were investigated to compare with the effects of {gamma}-ray irradiation. Electron beam irradiation was made changing the energy form 200 keV for 15 min to 500 keV for 5 min and a dose-depth curve was drawn for each electron energy. Indicator balls were used to examine the radiation effects. It became possible to make homogeneous irradiation onto a spherical surface of food by using the rotary system of the apparatus. It was demonstrated that satisfactory sterilizing effects as much as those of {gamma}-ray were obtainable by superficial treatments with low-energy electron. (M.N.)

  20. Development of the techniques for food processing with low-energy electron beam

    International Nuclear Information System (INIS)

    Todoroki, Setsuko; Hayashi, Toru

    1999-01-01

    This study aimed to construct a new electron beam irradiation apparatus which allows to perform homogeneous irradiation up to a certain depth of a spherical or granular material through rotating it. And the sterilizing effects of this apparatus on various kinds of spices such as black and white peppers (grains), turmeric (root), coriander (seed), basil (leaves) were investigated to compare with the effects of γ-ray irradiation. Electron beam irradiation was made changing the energy form 200 keV for 15 min to 500 keV for 5 min and a dose-depth curve was drawn for each electron energy. Indicator balls were used to examine the radiation effects. It became possible to make homogeneous irradiation onto a spherical surface of food by using the rotary system of the apparatus. It was demonstrated that satisfactory sterilizing effects as much as those of γ-ray were obtainable by superficial treatments with low-energy electron. (M.N.)

  1. Energy loss and thermalization of low-energy electrons

    International Nuclear Information System (INIS)

    LaVerne, J.A.; Mozumder, A.; Notre Dame Univ., IN

    1984-01-01

    Various processes involved in the moderation of low-energy electrons (< 10 keV in energy) have been delineated in gaseous and liquid media. The discussion proceeds in two stages. The first stage ends and the second stage begins when the electron energy equals the first excitation potential of the medium. The second stage ends with thermalization. Cross sections for electronic excitation and for the excitation (and de-excitation) of sub-electronic processes have been evaluated and incorporated in suitable stopping power and transport theories. Comparison between experiment and theory and intercomparisons between theories and experiments have been provided where possible. (author)

  2. Diagnosis and dynamics of low energy electron beams using DIADYN

    International Nuclear Information System (INIS)

    Marghitu, S.; Oproiu, C.; Toader, D.; Ruset, C.; Grigore, E.; Marghitu, O.; Vasiliu, M.

    2008-01-01

    The paper presents original results concerning electron beam diagnosis and dynamics using DIADYN, a low energy (10 - 50 kV), medium intensity (0.1 - 1 A) laboratory equipment. A key stage in the operation of DIADYN is the beam diagnosis, performed by the non-destructive, modified three-gradient method (MTGM). We concentrate on the better use of experimental and computational techniques, in order to improve the consistency of the results. At present, DIADYN is equipped with a hot filament vacuum electron source (VES), consisting of a convergent Pierce diode, working in a pulse mode. Since the plasma electron sources (PES) have a longer lifetime and produce higher beam currents, we discuss the possibility to replace the VES with a PES. Special attention is given to VES results in a functioning regime typical for a low energy glow discharge PES. (authors)

  3. Diagnosis and dynamics of low energy electron beams using DIADYN

    Energy Technology Data Exchange (ETDEWEB)

    Marghitu, S [Electrostatica, ICPE-CA S.A., Spaiul Unirii 313, Sector 3, RO-74204 Bucharest (Romania); Oproiu, C; Toader, D; Ruset, C; Grigore, E [National Institute for Laser, Plasma and Radiation Physics, PO Box MG-36, 409 Atomistilor Street, RO-76900 Bucharest-Magurele (Romania); Marghitu, O [Institute for Space Sciences, INCDLPFR, PO Box MG-23, RO-76911 Bucharest-Magurele (Romania); Vasiliu, M [Politehnica University, 313 Splaiul Independentei, RO-060032, Bucharest (Romania)

    2008-07-01

    The paper presents original results concerning electron beam diagnosis and dynamics using DIADYN, a low energy (10 - 50 kV), medium intensity (0.1 - 1 A) laboratory equipment. A key stage in the operation of DIADYN is the beam diagnosis, performed by the non-destructive, modified three-gradient method (MTGM). We concentrate on the better use of experimental and computational techniques, in order to improve the consistency of the results. At present, DIADYN is equipped with a hot filament vacuum electron source (VES), consisting of a convergent Pierce diode, working in a pulse mode. Since the plasma electron sources (PES) have a longer lifetime and produce higher beam currents, we discuss the possibility to replace the VES with a PES. Special attention is given to VES results in a functioning regime typical for a low energy glow discharge PES. (authors)

  4. Treatment of surfaces with low-energy electrons

    Czech Academy of Sciences Publication Activity Database

    Frank, Luděk; Mikmeková, Eliška; Lejeune, M.

    2017-01-01

    Roč. 407, JUN 15 (2017), s. 105-108 ISSN 0169-4332 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Low- energy electrons * Electron beam induced release * Graphene * Ultimate cleaning of surfaces Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 3.387, year: 2016

  5. Practical Use of Scanning Low Energy Electron Microscope (SLEEM)

    Czech Academy of Sciences Publication Activity Database

    Müllerová, Ilona; Mikmeková, Eliška; Mikmeková, Šárka; Konvalina, Ivo; Frank, Luděk

    2016-01-01

    Roč. 22, S3 (2016), s. 1650-1651 ISSN 1431-9276 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : scanning low energy * SLEEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.891, year: 2016

  6. Degradation of vitamin C by low-energy electrons

    Science.gov (United States)

    Abdoul-Carime, Hassan; Illenberger, Eugen

    2004-06-01

    We report on the degradation of gas phase vitamin C (ascorbic acid, AA) induced by low-energy electrons. In the energy range of (0-12) eV, different negatively charged fragments, attributed to the dehydro-ascorbic acid anion ((AA-H) -), OH -, O - and H -, are observed. The yield functions indicate that these ions are formed via dissociative electron attachment, DEA. While the formation of (AA-H) - is exclusively observed at sub-excitation energies (<1.5 eV), the other fragments arise from resonance features at higher energies. Possible implications of these observations for radiation damage and food treatment by high energy radiation are considered.

  7. Introduction to the theory of low-energy electron diffraction

    International Nuclear Information System (INIS)

    Fingerland, A.; Tomasek, M.

    1975-01-01

    An elementary introduction to the basic principles of the theory of low-energy electron diffraction is presented. General scattering theory is used to classify the hitherto known approaches to the problem (optical potential and one-electron approximation; formal scattering theory: Born expansion and multiple scattering; translational symmetry: Ewald construction; classification of LEED theories by means of the T matrix; pseudokinematical theory for crystal with clean surface and with an adsorbed monomolecular layer; dynamical theory; inclusion of inelastic collisions; discussion of a simple example by means of the band-structure approach)

  8. Low-energy electron scattering from molecules, biomolecules and surfaces

    CERN Document Server

    Carsky, Petr

    2011-01-01

    Since the turn of the 21st century, the field of electron molecule collisions has undergone a renaissance. The importance of such collisions in applications from radiation chemistry to astrochemistry has flowered, and their role in industrial processes such as plasma technology and lighting are vital to the advancement of next generation devices. Furthermore, the development of the scanning tunneling microscope highlights the role of such collisions in the condensed phase, in surface processing, and in the development of nanotechnology.Low-Energy Electron Scattering from Molecules, Biomolecule

  9. Low energy electron beams for industrial and environmental applications

    CERN Document Server

    Skarda, Vlad

    2017-01-01

    EuCARD-2 Workshop, 8-9 December 2016, Warsaw, Poland. Organizers: Science and Technology Facilities Council, UK CERN - The European Organization for Nuclear Research, Switzerland, Institute of Nuclear Chemistry and Technology, Poland, Fraunhofer Institute for Electron Beam and Plasma Technology, Germany, Warsaw University of Technology, Poland. An article presents short information about EuCARD-2 Workshop “Low energy electron beams for industrial and environmental applications”, which was held in December 2016 in Warsaw. Objectives, main topics and expected output of meeting are described. List of organizers is included.

  10. An evaluation of low-energy x-ray and cobalt-60 irradiations of MOS transistors

    International Nuclear Information System (INIS)

    Dozier, C.M.; Fleetwood, D.M.

    1987-01-01

    An evaluation of methodologies for irradiating MOS transistors with low-energy x-ray and Co-60 sources has been performed. The authors find that comparisons of voltage shifts produced by bulk trapped charge and interface states in MOS transistors irradiated using two different low energy x-ray sources (an ARACOR 10 keV W source and an 8 keV Cu source) agree to within better than 30 percent. This quality of agreement is similar in magnitude to that between MOS devices irradiated by different Co-60 sources. In contrast, the measurements indicate that interlaboratory comparisons of ratios of shifts produced by x-ray and Co-60 sources can lead to differences in ratios as large as a factor of --1.7. Improved electron-hole recombination data for oxides is presented. This recombination correction, in conjunction with a correction for interface dose enhancement, is used to predict the ratios of shifts produced by x-ray and Co-60 sources. However, the results show that corrections for electron-hole recombination and interface does enhancement do not, by themselves, adequately predict the field dependent behavior of these transistors

  11. Elastic scattering of low-energy electrons with Sr atoms

    International Nuclear Information System (INIS)

    Yuan, J.; Zhang, Z.; Wan, H.

    1990-01-01

    Static-exchange, plus correlation-polarization-potential calculations are performed for elastic low-energy electron scattering from Sr atoms while paying attention to the low-lying shape resonances. The correlation potential is calculated both with and without a scaling factor. A 2 D-shape resonance is produced at 1.0 eV with a parameter-free, and at 1.25 eV with a scaled, correlation potential. No 2 P-shape resonances are predicted, but evidence to support the existence of a stable negative ion Sr - in the 5s 2 5p electron configuration is given from the viewpoint of electron scattering. The bound energy of the extra electron in the negative ion is estimated by transforming the phase shift of the corresponding partial wave into the polarization quantum-defect number and extrapolating the number from positive to negative energies

  12. Low-Energy Electron Scattering by Sugarcane Lignocellulosic Biomass Molecules

    Science.gov (United States)

    Oliveira, Eliane; Sanchez, Sergio; Bettega, Marcio; Lima, Marco; Varella, Marcio

    2012-06-01

    The use of second generation (SG) bioethanol instead of fossil fuels could be a good strategy to reduce greenhouse gas emissions. However, the efficient production of SG bioethanol has being a challenge to researchers around the world. The main barrier one must overcome is the pretreatment, a very important step in SG bioethanol aimed at breaking down the biomass and facilitates the extraction of sugars from the biomass. Plasma-based treatment, which can generate reactive species, could be an interesting possibility since involves low-cost atmospheric-pressure plasma. In order to offer theoretical support to this technique, the interaction of low-energy electrons from the plasma with biomass is investigated. This study was motived by several works developed by Sanche et al., in which they understood that DNA damage arises from dissociative electron attachment, a mechanism in which electrons are resonantly trapped by DNA subunits. We will present elastic cross sections for low-energy electron scattering by sugarcane biomass molecules, obtained with the Schwinger multichannel method. Our calculations indicate the formation of π* shape resonances in the lignin subunits, while a series of broad and overlapping σ* resonances are found in cellulose and hemicellulose subunits. The presence of π* and σ* resonances could give rise to direct and indirect dissociation pathways in biomass. Then, theoretical resonance energies can be useful to guide the plasma-based pretreatment to break down specific linkages of interest in biomass.

  13. Studies on functional polymer films utilizing low energy electron beam

    International Nuclear Information System (INIS)

    Ando, Masayuki

    1992-01-01

    Also in adhesives and tackifiers, with the expansion of the fields of application, the required characteristics have become high grade and complex. As one of them, the instantaneous hardening of adhesives can be taken up. In the field of lamination works, the low energy type electron beam accelerators having the linear filament of accelerating voltage below 300 kV were developed in 1970s, and the interest in the development of electron beam-handened adhesives has heightend. The authors have carried out research aiming at heightening the functions of the polymer films obtained by electron beam hardening reaction, and developed the adhesives. In this report, the features of electron beam hardening reaction, the structure and properties of electron beam-hardened polymer films and the molecular design of electron beam-hardened monomer oligomers are described. The feature of electron beam hardening reaction is the cross-linking of high degree as the structure of oligomers is maintained. By controlling the structure at the time of electron beam hardening, the heightening of the functions of electron beam-hardened polymer films is feasible. (K.I.)

  14. Can Low Energy Electrons Affect High Energy Physics Accelerators?

    International Nuclear Information System (INIS)

    Cimino, Roberto

    2004-01-01

    The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at which low-energy electrons (<∼ 20 eV) impacting on the wall create secondaries or are elastically reflected. It is shown that the ratio of reflected to true-secondary electrons increases for decreasing energy and that the SEY approaches unity in the limit of zero primary electron energy

  15. Interpretation of diffuse low-energy electron diffraction intensities

    International Nuclear Information System (INIS)

    Saldin, D.K.; Pendry, J.B.; Van Hove, M.A.; Somorjai, G.A.

    1985-01-01

    It is shown that the diffuse low-energy electron diffraction (LEED) that occurs between sharp LEED beams can be used to determine the local bonding configuration near disordered surface atoms. Two approaches to the calculation of diffuse LEED intensities are presented for the case of lattice-gas disorder of an adsorbate on a crystalline substrate. The capabilities of this technique are most similar to those of near-edge extended x-ray absorption fine structure, but avoid the restrictions due to the use of photons

  16. Vibrational and electronic excitation of hexatriacontane thin films by low energy electron impact

    International Nuclear Information System (INIS)

    Vilar, M.R.; Schott, M.; Pfluger, P.

    1990-01-01

    Thin polycrystalline films of hexatriacontane (HTC) were irradiated with low energy (E=0.5--15 eV) electrons, and off-specular backscattered electron spectra were measured. Below E∼7 eV, single and multiple vibrational excitations only are observed, which relax the electrons down to the bottom of the HTC conduction band. Due to the negative electron affinity of HTC, thermal electrons are emitted into vacuum. Structure in the backscattered electron current at kinetic energies about 1.5 and 4 eV are associated to conduction band density of states. Above E∼7 eV, the dominant losses correspond to electronic excitations, excitons, or above a threshold (energy of the electron inside the HTC film) at 9.2±0.1 eV, electron--hole pair generation. The latter process is very efficient and reaches a yield of the order of one ∼11 eV. Evidence for chemical reaction above E∼4 eV is observed

  17. Medipix 2 detector applied to low energy electron microscopy

    International Nuclear Information System (INIS)

    Gastel, R. van; Sikharulidze, I.; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

    2009-01-01

    Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.

  18. Medipix 2 detector applied to low energy electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gastel, R. van, E-mail: R.vanGastel@utwente.nl [University of Twente, MESA Institute for Nanotechnology, P.O. Box 217, NL-7500 AE Enschede (Netherlands); Sikharulidze, I. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, NL-2300 RA Leiden (Netherlands); Schramm, S. [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); Abrahams, J.P. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, NL-2300 RA Leiden (Netherlands); Poelsema, B. [University of Twente, MESA Institute for Nanotechnology, P.O. Box 217, NL-7500 AE Enschede (Netherlands); Tromp, R.M. [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands)

    2009-12-15

    Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.

  19. Low-energy irradiation effects of gas cluster ion beams

    International Nuclear Information System (INIS)

    Houzumi, Shingo; Takeshima, Keigo; Mochiji, Kozo; Toyoda, Noriaki; Yamada, Isao

    2007-01-01

    A cluster-ion irradiation system with cluster-size selection has been developed to study the effects of the cluster size for surface processes using cluster ions. A permanent magnet with a magnetic field of 1.2 T is installed for size separation of large cluster ions. Trace formations at HOPG surface by the irradiation with size-selected Ar-cluster ions under acceleration energy of 30 keV were investigated by a scanning tunneling microscopy. Generation behavior of the crater-like traces is strongly affected by the number of constituent atoms (cluster size) of the irradiating cluster ion. When the incident cluster ion is composed of 100-3000 atoms, crater-like traces are observed on the irradiated surfaces. In contrast, such traces are not observed at all with the irradiation of the cluster-ions composed of over 5000 atoms. Such the behavior is discussed on the basis of the kinetic energy per constituent atom of the cluster ion. To study GCIB irradiation effects against macromolecule, GCIB was irradiated on DNA molecules absorbed on graphite surface. By the GCIB irradiation, much more DNA molecules was sputtered away as compared with the monomer-ion irradiation. (author)

  20. Detectors for low energy electron cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Carlier, F. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-02-15

    Low-energy operation of RHIC is of particular interest to study the location of a possible critical point in the QCD phase diagram. The performance of RHIC at energies equal to or lower than 10 GV/nucleon is limited by nonlinearities, Intra-BeamScattering (IBS) processes and space-charge effects. To successfully address the luminosity and ion store lifetime limitations imposed by IBS, the method of electron cooling has been envisaged. During electron cooling processes electrons are injected along with the ion beam at the nominal ion bunch velocities. The velocity spread of the ion beam is reduced in all planes through Coulomb interactions between the cold electron beam and the ion beam. The electron cooling system proposed for RHIC will be the first of its kind to use bunched beams for the delivery of the electron bunches, and will therefore be accompanied by the necessary challenges. The designed electron cooler will be located in IP2. The electron bunches will be accelerated by a linac before being injected along side the ion beams. Thirty consecutive electron bunches will be injected to overlap with a single ion bunch. They will first cool the yellow beam before being extracted, turned by 180-degrees, and reinjected into the blue beam for cooling. As such, both the yellow and blue beams will be cooled by the same ion bunches. This will pose considerable challenges to ensure proper electron beam quality to cool the second ion beam. Furthermore, no ondulator will be used in the electron cooler so radiative recombination between the ions and the electrons will occur.

  1. Charge-coupled device area detector for low energy electrons

    International Nuclear Information System (INIS)

    Horacek, Miroslav

    2003-01-01

    A fast position-sensitive detector was designed for the angle- and energy-selective detection of signal electrons in the scanning low energy electron microscope (SLEEM), based on a thinned back-side directly electron-bombarded charged-coupled device (CCD) sensor (EBCCD). The principle of the SLEEM operation and the motivation for the development of the detector are explained. The electronics of the detector is described as well as the methods used for the measurement of the electron-bombarded gain and of the dark signal. The EBCCD gain of 565 for electron energy 5 keV and dynamic range 59 dB for short integration time up to 10 ms at room temperature were obtained. The energy dependence of EBCCD gain and the detection efficiency are presented for electron energy between 2 and 5 keV, and the integration time dependence of the output signals under dark conditions is given for integration time from 1 to 500 ms

  2. Low energy electron point source microscopy: beyond imaging

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Andre; Goelzhaeuser, Armin [Physics of Supramolecular Systems and Surfaces, University of Bielefeld, Postfach 100131, 33501 Bielefeld (Germany)

    2010-09-01

    Low energy electron point source (LEEPS) microscopy has the capability to record in-line holograms at very high magnifications with a fairly simple set-up. After the holograms are numerically reconstructed, structural features with the size of about 2 nm can be resolved. The achievement of an even higher resolution has been predicted. However, a number of obstacles are known to impede the realization of this goal, for example the presence of electric fields around the imaged object, electrostatic charging or radiation induced processes. This topical review gives an overview of the achievements as well as the difficulties in the efforts to shift the resolution limit of LEEPS microscopy towards the atomic level. A special emphasis is laid on the high sensitivity of low energy electrons to electrical fields, which limits the structural determination of the imaged objects. On the other hand, the investigation of the electrical field around objects of known structure is very useful for other tasks and LEEPS microscopy can be extended beyond the task of imaging. The determination of the electrical resistance of individual nanowires can be achieved by a proper analysis of the corresponding LEEPS micrographs. This conductivity imaging may be a very useful application for LEEPS microscopes. (topical review)

  3. Cost analysis of low energy electron accelerator for film curing

    International Nuclear Information System (INIS)

    Ochi, Masafumi

    2003-01-01

    Low energy electron accelerators are recognized as one of the advanced curing means of converting processes for films and papers. In the last three years the price of the accelerator equipment has been greatly reduced. The targeted application areas are mainly processes of curing inks, coatings, and adhesives to make packaging materials. The operating cost analyses were made for electron beam (EB) processes over the conventional ones without EB. Then three new proposals for cost reduction of EB processes are introduced. Also being developed are new EB chemistries such as coatings, laminating adhesives and inks. EB processes give instantaneous cure and EB chemistries are basically non solvent causing less VOC emission to the environment. These developments of both equipment and chemistries might have a potential to change conventional packaging film industries. (author)

  4. DNA comet assay for rice seeds treated with low energy electrons ('soft-electrons')

    International Nuclear Information System (INIS)

    Todoriki, Setsuko; Hayashi, Toru

    1999-01-01

    As rice seeds are sometimes contaminated with phytopathogenic organisms such as blast disease fungi and nematodes, a novel non-chemical disinfection method for rice seeds is highly required. In order to develop a disinfection method, the effect of low energy electron ('soft-electrons') on seed DNA was examined by using the neutral comet assay. Rice seeds (whole grain) were treated with electrons of different acceleration voltages (180 kV to 1 MV) at a dose of 5 kGy. Nucleus suspensions were prepared from whole brown rice and subjected to electrophoresis. DNA from un-irradiated (control) seeds relaxed and produced comets with a short tail, most of the comets distributed within the range of comet length between 30 μm to 70 μm. In the case of seeds treated with electrons at acceleration voltages up to 190 kV, cells without seed coats were not damaged and the frequency histograms of comet length showed almost the same pattern as that for control. At acceleration voltages higher than 200 kV, the cells were distributed into two categories; DNA comets with a short tail (with little DNA damages, less than 70 μm in the comet length) and DNA comets with long tails (with sever strand breaks, more than 130 μm in the comet length). The ratios of damaged cells increased with increasing acceleration voltage. The growths of rice seedlings were not affected by the treatment with electrons at up to 200 kV. On the contrary, the cells of gamma-irradiated seed showed small variations in the comet length, and which were depending on radiation dose. The individual cells of gamma-irradiated seeds at 1 kGy showed shorter comet than the damaged cells with soft electron, seed treated with gamma rays (1-5 kGy) did not shoot nor root. (author)

  5. Treatment of surfaces with low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Frank, L., E-mail: ludek@isibrno.cz [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); Mikmeková, E. [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven (Netherlands); Lejeune, M. [LPMC – Faculte des Sciences d’Amiens, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex 2 (France)

    2017-06-15

    Highlights: • Using proper irradiation parameters, adsorbed hydrocarbons are released from surfaces. • Slow electrons remove hydrocarbons instead of depositing carbon. • Prolonged irradiation with very slow electrons does not create defects in graphene. - Abstract: Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

  6. A simple irradiation facility for radiobiological experiments with low energy protons from a cyclotron

    International Nuclear Information System (INIS)

    Mukherjee, B.

    1982-01-01

    An experimental facility for irradiation of small biological targets with low-energy protons has been developed. The depth-dose distribution in soft-tissue is calculated from the proton energy spectrum. (orig.)

  7. Vibrational excitation of D2 by low energy electrons

    International Nuclear Information System (INIS)

    Buckman, S.J.; Phelps, A.V.

    1985-01-01

    Excitation coefficients for the production of vibrationally exicted D 2 by low energy electrons have been determined from measurements of the intensity of infrared emission from mixtures of D 2 and small concentrations of CO 2 or CO. The measurements were made using the electron drift tube technique and covered electric field to gas density ratios (E/n) from (5 to 80) x 10 -21 V m 2 , corresponding to mean electron energies between 0.45 and 4.5 eV. The CO 2 and CO concentrations were chosen to allow efficient excitation transfer from the D 2 to the carbon containing molecule, but to minimize direct excitation of the CO 2 or CO. The measured infrared intensities were normalized to predicted values for N 2 --CO 2 and N 2 --CO mixtures at E/n where the efficiency of vibrational excitation is known to be very close to 100%. The experimental excitation coefficients are in satisfactory agreement with predictions based on electron--D 2 cross sections at mean electron energies below 1 eV, but are about 50% too high at mean energies above about 2 eV. Application of the technique to H 2 did not yield useful vibrational excitation coefficients. The effective coefficients in H 2 --CO 2 mixtures were a factor of about 3 times the predicted values. For our H 2 --CO mixtures the excitation of CO via excitation transfer from H 2 is small compared to direct electron excitation of CO molecules. Published experiments and theories on electron--H 2 and electron--D 2 collisions are reviewed to obtain the cross sections used in the predictions

  8. Wettability Modification of Nanomaterials by Low-Energy Electron Flux

    Directory of Open Access Journals (Sweden)

    Torchinsky I

    2009-01-01

    Full Text Available Abstract Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc. of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials.

  9. Low energy electron microscopy imaging using Medipix2 detector

    International Nuclear Information System (INIS)

    Sikharulidze, I.; Gastel, R. van; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

    2011-01-01

    Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

  10. Low energy electron microscopy imaging using Medipix2 detector

    Energy Technology Data Exchange (ETDEWEB)

    Sikharulidze, I., E-mail: irakli@chem.leidenuniv.nl [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Gastel, R. van [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Schramm, S. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); Abrahams, J.P. [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Poelsema, B. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Tromp, R.M. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands)

    2011-05-15

    Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

  11. New directions in low energy electron molecule collision calculations

    International Nuclear Information System (INIS)

    Burke, P.G.; Noble, C.J.

    1982-01-01

    New theoretical and computational methods for studying low energy electron molecule collisions are discussed. Having considered the fixed-nuclei approximation and the form of the expansion of the total collision wavefunction, the various approximations which have been made are examined, including the static plus model exchange approximation, the static exchange approximation and the close coupling approximation, particular attention being paid to methods of including the molecular charge polarisation. Various ways which have been developed to solve the resultant equations are discussed and it is found that there is increasing emphasis being given to methods which combine the advantages of discrete multi-centre analytic bases with single centre numerical bases. (U.K.)

  12. Track structure analysis illustrating the prominent role of low-energy electrons in radiobiological effects of low-LET radiations

    International Nuclear Information System (INIS)

    Nikjoo, H.; Goodhead, D.T.

    1991-01-01

    Monte Carlo track structure methods have been used to illustrate the importance of low-energy electrons produced by low-LET radiations. It is shown that these low-energy secondary electrons contribute substantially to the dose in all low-LET irradiations and are particularly efficient at producing highly localized clusters of atomic damage which may be responsible for a major part of the biological effectiveness of low-LET radiations. The data generated by Monte Carlo track structure techniques and by earlier semi-analytical methods based on the LET concept have been compared in terms of cumulative and differential fractions of total dose absorbed as a function of electron energy. The data show that low-energy secondary electrons account for up to nearly 50% of the total dose imparted to a medium when irradiated with electrons or photons. (author)

  13. Intensive beam dosimetry of accelerated electrons of low energy

    International Nuclear Information System (INIS)

    Oproiu, C.

    1984-01-01

    Dosimetric control of electron beams ranging between 0.3 MeV and 10 MeV is treated using proper dosimetric methods relying on calorimetry, Tricke chemical solution, dosimetric film of cellulose triacetate. Proper methods are pointed out for measurements in inhomogeneous fields, bringing into evidence the results obtained in deep dose distributions and on the surface of irradiated material. A measuring method of dose distribution in depth by means of an assembly with calorimetric elements, as well as a practical method to pointing out dose distribution and equidose curves along the depth of irradiated electric cable depth are presented. In order to find out the main sizes of accelerated electron beam one uses proper devices relying on Faraday cylinder, total absorption calorimeter, ionization chambers. (author)

  14. Dμ-A new concept in industrial low-energy electron dosimetry

    International Nuclear Information System (INIS)

    Helt-Hansen, Jakob; Miller, Arne; Sharpe, Peter; Laurell, Bengt; Weiss, Doug; Pageau, Gary

    2010-01-01

    Irradiation with low-energy electrons (100-300 keV) results in dose gradients across the thickness of the dosimeters that are typically used for dose measurement at these energies. This leads to different doses being measured with different thickness dosimeters irradiated at the same electron beam, resulting in difficulties in providing traceable dose measurements using reference dosimeters. In order to overcome these problems a new concept is introduced of correcting all measured doses to the average dose in the first micrometer-D μ . We have applied this concept to dose measurements with dosimeters of different thickness at two electron accelerators operating over a range of energies. The uncertainties of the dose measurements were evaluated, and it was shown that the dose in terms of D μ was the same at each energy for all dosimeters within the measurement uncertainty. Using the concept of D μ it is therefore possible to calibrate and measure doses from low-energy electron irradiations with measurement traceability to national standards.

  15. Low energy electron-driven damage in biomolecules

    International Nuclear Information System (INIS)

    Sanche, L.

    2005-01-01

    The damage induced by the impact of low energy electrons (LEE) on biomolecules is reviewed from a radiobiological perspective with emphasis on transient anion formation. The major type of experiments, which measure the yields of fragments produced as a function of incident electron energy (0.1 - 30 eV), are briefly described. Theoretical advances are also summarized. Several examples are presented from the results of recent experiments performed in the gas-phase and on bio-molecular films bombarded with LEE under ultra-high vacuum conditions. These include the results obtained from DNA films and those obtained from the fragmentation of elementary components of the DNA molecule (i.e., the bases, sugar and phosphate group analogs and oligonucleotides) and of proteins (e.g. amino acids). By comparing the results from different experiments and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the biomolecules and the production of single- and double-strand breaks in DNA. Below 15 eV, electron resonances (i.e., the formation of transient anions) play a dominant role in the fragmentation of all biomolecules investigated. These transient anions fragment molecules by decaying into dissociative electronically excited states or by dissociating into a stable anion and a neutral radical. These fragments can initiate further reactions within large biomolecules or with nearby molecules and thus cause more complex chemical damage. Dissociation of a transient anion within DNA may occur by direct electron attachment at the location of dissociation or by electron transfer from another subunit. Damage to DNA is dependent on the molecular environment, topology, type of counter ion, sequence context and chemical modifications. (author)

  16. Shape resonances in low-energy-electron collisions with halopyrimidines

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Alessandra Souza; Bettega, Márcio H. F., E-mail: bettega@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, Paraná (Brazil)

    2013-12-07

    We report calculated cross sections for elastic collisions of low-energy electrons with halopyrimidines, namely, 2-chloro, 2-bromo, and 5-bromopyrimidine. We employed the Schwinger multichannel method with pseudopotentials to compute the cross sections in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 10 eV. We found four shape resonances for each molecule: three of π* nature localized on the ring and one of σ* nature localized along the carbon–halogen bond. We compared the calculated positions of the resonances with the electron transmission spectroscopy data measured by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)]. In general the agreement between theory and experiment is good. In particular, our results show the existence of a π* temporary anion state of A{sub 2} symmetry for all three halopyrimidines, in agreement with the dissociative electron attachment spectra also reported by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)].

  17. The Role of Low-Energy Electrons in Astrochemistry: A Tale of Two Molecules

    Science.gov (United States)

    Arumainayagam, Chris; Cambell, Jyoti; Leon Sanche, Michael Boyer, and Petra Swiderek.

    2016-06-01

    In the interstellar medium, UV photolysis of ice mantles encasing dust grains is thought to be the mechanism that drives the synthesis of “complex” molecules. The source of this reaction-initiating UV light is assumed to be local because externally-sourced UV radiation cannot pass through the ice-containing dark, dense molecular clouds. Externally sourced cosmic rays (Emax ~ 1020 eV), in addition to producing UV light within these clouds, also produce large numbers of low-energy (≤ 20 eV) secondary electrons. The goal of our studies is to understand the low-energy electron-induced processes that occur when high-energy cosmic rays interact with interstellar ices. Using electron stimulated desorption (ESD), post-irradiation temperature-programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS), we have investigated the radiolysis initiated by electrons in condensed methanol and ammonia at ~ 90 K under ultrahigh vacuum (1×10-9 Torr) conditions. We have identified fifteen low-energy (≤ 20 eV) electron-induced methanol radiolysis products, many of which have been previously identified as being formed by methanol UV photolysis in the interstellar medium. We have also found evidence for the electron-induced formation from ammonia of hydrazine (N2H4), diazene (N2H2), cyclotriazane/triazene (N3H3) and triazane (N3H5). We have investigated the reaction yields’ dependence on film thickness, irradiation time, incident current, electron energy, and metal substrate. These results provide a basis from which we can begin to understand the mechanisms by which methanol and ammonia can form more complex species in cosmic ices. Studies such as ours may ultimately help us better understand the initial stages of the genesis of life.

  18. Treatment of surfaces with low-energy electrons

    Science.gov (United States)

    Frank, L.; Mikmeková, E.; Lejeune, M.

    2017-06-01

    Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

  19. Current mapping of low-energy (120 eV) helium and hydrogen irradiated tungsten by conductive atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Endo, Takashi [Nano-micro Materials Analysis Laboratory, Hokkaido University, Sapporo (Japan); Bi, Zhenghua; Yan, Weibin [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Ohnuki, Somei [Nano-micro Materials Analysis Laboratory, Hokkaido University, Sapporo (Japan); Yang, Qi; Ni, Weiyuan [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Liu, Dongping, E-mail: dongping.liu@dlnu.edu.cn [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China)

    2017-04-01

    Both conductive atomic force microscopy (CAFM) and transmission electron microscopy have been used to characterize the defects or He bubbles in low-energy (120 eV) H and He irradiated tungsten (W). By a comparative study, we find that the current mapping from CAFM is very sensitive in the detection of nanometer-sized defects in low-energy H and He irradiated W. Our calculation confirms that the resistance change in H and He irradiated W is strongly affected by the distance between atomic force microscopy tip and defects/He bubbles. CAFM can accurately detect defects/He bubbles in the W surface layer, however, it is infeasible to measure them in the deep layer (>20 nm), especially due to the existence of defects in the surface layer.

  20. High-Resolution Measurements of Low-Energy Conversion Electrons

    CERN Multimedia

    Gizon, A; Putaux, J

    2002-01-01

    Measurements of low-energy internal conversion electrons have been performed with high energy resolution in some N = 105 odd and odd-odd nuclei using a semi-circular spectrograph associated to a specific tape transport system. These experiments aimed to answer the following questions~: \\begin{itemize} \\item Do M3 isomeric transitions exist in $^{183}$Pt and $^{181}$Os, isotones of $^{184}$Au~? \\item Are the neutron configurations proposed to describe the isomeric and ground states of $^{184}$Au right or wrong~? \\item Does it exist an isomeric state in $^{182}$Ir, isotone of $^{181}$Os, $^{183}$Pt and $^{184}$Au~? \\item What are the spin and parity values of the excited states of $^{182}$Ir~? \\end{itemize} In $^{183}$Pt, the 35.0 keV M3 isomeric transition has been clearly observed and the reduced transition probability has been determined. The deduced hindrance factor is close to that observed in the neighbouring odd-odd $^{184}$Au nucleus. This confirms the neutron configurations previously proposed for the ...

  1. The use of low energy electron accelerator for processing of liquid matter in Indonesia

    International Nuclear Information System (INIS)

    Danu, Sugiarto

    2003-01-01

    Activities of radiation processing in Indonesia covering various fields are reviewed. The low and medium energy electron accelerator specially designed for radiation processing of liquid materials is introduced. P3TIR-BATAN is mostly engaged in radiation processing in general with Co-60 source and electron accelerators (300 keV, 50 mA and 2 MeV, 10 mA). A private company, Gajah Tunggal, has an accelerator of 500 keV, 20 mA. The use of low energy electron accelerator to irradiate liquid matter matter such as natural rubber latex, polysaccharides, starch, chitosan and other natural polymers in Indonesia are reported and future program of national research cooperation between government institutions and private companies are described. (S. Ohno)

  2. Performance studies of the vibration wire monitor on the test stand with low energy electron beam

    International Nuclear Information System (INIS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    2015-01-01

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic. (author)

  3. Excitation and dissociation of molecules by low-energy (0-15 eV) electrons

    International Nuclear Information System (INIS)

    Verhaart, G.J.

    1980-01-01

    The author deals with excitation and dissociation processes which result from the interaction between low-energy (0.15 eV) electrons and molecules. Low-energy electron-impact spectroscopy is used to gain a better knowledge of the electronic structure of halomethanes, ethylene and some of its halogen substituted derivatives, and some more complex organic molecules. (Auth.)

  4. Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

    Science.gov (United States)

    Ozur, G. E.; Proskurovsky, D. I.

    2018-01-01

    This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

  5. Photocarrier Radiometry for Non-contact Evaluation of Monocrystalline Silicon Solar Cell Under Low-Energy (< 200 keV) Proton Irradiation

    Science.gov (United States)

    Oliullah, Md.; Liu, J. Y.; Song, P.; Wang, Y.

    2018-06-01

    A three-layer theoretical model is developed for the characterization of the electronic transport properties (lifetime τ, diffusion coefficient D, and surface recombination velocity s) with energetic particle irradiation on solar cells using non-contact photocarrier radiometry. Monte Carlo (MC) simulation is carried out to obtain the depth profiles of the proton irradiation layer at different low energies (solar cells are investigated under different low-energy proton irradiation, and the carrier transport parameters of the three layers are obtained by best-fitting of the experimental results. The results show that the low-energy protons have little influence on the transport parameters of the non-irradiated layer, but high influences on both of the p and n-region irradiation layers which are consisted of MC simulation.

  6. Polymeric reaction of polymer-monomer system for pressure sensitive adhesives by low energy electron beam

    International Nuclear Information System (INIS)

    Takiguchi, R.; Uryu, T.

    1985-01-01

    Application of low-energy electron beam to non-solvent type pressure sensitive adhesives is investigated. The adhesive properties such as peel strength and holding time (dead-load strength) were closely related to the reaction of acrylate polymer-monomer systems. The reaction behavior is elucidated by combining the measurement of gel fraction, infrared spectrum of gel, and the molecular weight distribution detected by gel permeation chromatography. It was important for the production of pressure sensitive adhesives by electron beam that the adhesive with high peel strength and long holding time is composed of a proper combination of three factors, that is, about 35% gel fraction, 25% monomer units in gel, and 15% graft efficiency by irradiating the polymer-monomer system containing low molecular weight poly (butyl acrylate). (author)

  7. Deep-level transient spectroscopy of low-energy ion-irradiated silicon

    DEFF Research Database (Denmark)

    Kolkovsky, Vladimir; Privitera, V.; Nylandsted Larsen, Arne

    2009-01-01

     During electron-gun deposition of metal layers on semiconductors, the semiconductor is bombarded with low-energy metal ions creating defects in the outermost surface layer. For many years, it has been a puzzle why deep-level transient spectroscopy spectra of the as-deposited, electron-gun evapor...

  8. Atomic effects of electrons and protons at low energies

    International Nuclear Information System (INIS)

    Hippler, R.

    1985-01-01

    Some aspects of electronic and atomic collisions are discussed. Impact ionization by electrons and protons, and electron bremsstrahlung processes are considered in some detail. Emphasis is also given to (uncorrelated and correlated) many-electron processes, which are of particular importance in collisions of highly-charged ions with atoms. 84 refs., 15 figs

  9. Observation of second harmonics in laser-electron scattering using low energy electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Iinuma, Masataka [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)]. E-mail: iinuma@hiroshima-u.ac.jp; Matsukado, Koji [Venture Business Laboratory, Hiroshima University, 1-313 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan); Endo, Ichita [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Hashida, Masaki [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Hayashi, Kenji [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Kohara, Akitsugu [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Matsumoto, Fumihiko [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Nakanishi, Yoshitaka [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Sakabe, Shuji [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Shimizu, Seiji [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tauchi, Toshiaki [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yamamoto, Ken [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Takahashi, Tohru [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)

    2005-10-17

    We observed photon generation in the second harmonic region in collisions of 10 keV free electrons and the intense laser beam with the peak intensity of 4.0x10{sup 15} W/cm{sup 2}. Observed photon yield was 3 orders of magnitude higher than expectation from the nonlinear Compton scattering. The observation indicates necessity of further investigation for the interaction between the intense laser field and the low energy electron beam.

  10. Study and realization of an electron gun at low energy

    International Nuclear Information System (INIS)

    Camus, P.

    1977-01-01

    This work presents the theoretical concepts and experimental design of an electron gun. This gun is working in the weak energy range and the focus position is independant of electron energy measurements and analysis methods of the electron beam are described [fr

  11. Electron-induced desorption of europium atoms from oxidized tungsten surface: concentration dependence of low-energy peak

    CERN Document Server

    Davydov, S Y

    2002-01-01

    One discusses nature of electron induced desorption of Eu sup 0 europium atoms under E sub e irradiating electron low-energies (approx 30 eV) and peculiarities of yield dependence of Eu sup 0 atoms on their concentration at oxidized tungsten surface. Primary act of vacancy origination in europium adatom inner 5p-shell turned to be the determining stage. Evaluations have shown that just the first of two possible scenarios of ionization (electron intra-atomic to Eu adatom external quasi-level or realise of knocked out electron into vacuum) leads to Eu sup 0 desorption. One determined concentration threshold for yield of Eu sup 0 atoms

  12. Low energy helium ion irradiation induced nanostructure formation on tungsten surface

    International Nuclear Information System (INIS)

    Al-Ajlony, A.; Tripathi, J.K.; Hassanein, A.

    2017-01-01

    We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10 24 –1.6 × 10 25 ions m −2 ), and flux (2.0 × 10 20 –5.5 × 10 20 ion m −2 s −1 ). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

  13. Low energy helium ion irradiation induced nanostructure formation on tungsten surface

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ajlony, A., E-mail: montaserajlony@yahoo.com; Tripathi, J.K.; Hassanein, A.

    2017-05-15

    We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10{sup 24}–1.6 × 10{sup 25} ions m{sup −2}), and flux (2.0 × 10{sup 20}–5.5 × 10{sup 20} ion m{sup −2} s{sup −1}). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

  14. Surface influence on convoy electron emission at low energies

    International Nuclear Information System (INIS)

    Sanchez, E.A.

    1988-01-01

    It is studied the dependence of the production of convoy electrons induced by H + - 60 KeV with surface conditions of Al targets by in situ deposition of Na and O. The conclusion is that convoy electron production increases with the work function of the surface. (A.C.A.S.) [pt

  15. Low energy electron attachment to the uracil molecule

    International Nuclear Information System (INIS)

    Hanel, G.; Gstir, B.; Denifl, S.; Scheier, P.; Maerk, T.D.; Farizon, B.; Farizon, M.

    2002-01-01

    Using a recently constructed high resolution crossed beam apparatus involving a hemispherical electron monochromator, electron attachment to the uracil molecule C 4 H 4 N 2 O 2 was studied. The electron energy range investigated was in the region between 0 and 12 eV. What will happen when slow electrons are colliding with the cellular RNA compound uracil was the objective of this investigation. The following anion fragments were detected: (C 4 H 3 N 2 O 2 ) - , OCN - , (H 2 C 3 NO) - , CN - , O - . The most important result was that within the detection efficiency any traces of the parent anion were observed. The most intense fragment anion appeared on a mass to charge ratio 111 amu., it corresponds to a uracil molecule missing one hydrogen. Another observation was whereas the parent minus H anion is observed at zero electron energy, all other fragments appear in other range. (nevyjel)

  16. Low-energy collisions between electrons and BeD+

    Science.gov (United States)

    Niyonzima, S.; Pop, N.; Iacob, F.; Larson, Å; Orel, A. E.; Mezei, J. Zs; Chakrabarti, K.; Laporta, V.; Hassouni, K.; Benredjem, D.; Bultel, A.; Tennyson, J.; Reiter, D.; Schneider, I. F.

    2018-02-01

    Multichannel quantum defect theory is applied in the treatment of the dissociative recombination and vibrational excitation processes for the BeD+ ion in the 24 vibrational levels of its ground electronic state ({{X}}{}1{{{Σ }}}+,{v}{{i}}+=0\\ldots 23). Three electronic symmetries of BeD** states ({}2{{\\Pi }}, {}2{{{Σ }}}+, and {}2{{Δ }}) are considered in the calculation of cross sections and the corresponding rate coefficients. The incident electron energy range is 10-5-2.7 eV and the electron temperature range is 100-5000 K. The vibrational dependence of these collisional processes is highlighted. The resulting data are useful in magnetic confinement fusion edge plasma modeling and spectroscopy, in devices with beryllium based main chamber materials, such as ITER and JET, and operating with the deuterium-tritium fuel mix. An extensive rate coefficients database is presented in graphical form and also by analytic fit functions whose parameters are tabulated in the supplementary material.

  17. Low-energy electron inelastic mean free path in materials

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen-Truong, Hieu T., E-mail: nguyentruongthanhhieu@tdt.edu.vn [Theoretical Physics Research Group & Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 756636 (Viet Nam)

    2016-04-25

    We show that the dielectric approach can determine electron inelastic mean free paths in materials with an accuracy equivalent to those from first-principle calculations in the GW approximation of many-body theory. The present approach is an alternative for calculating the hot-electron lifetime, which is an important quantity in ultrafast electron dynamics. This approach, applied here to solid copper for electron energies below 100 eV, yields results in agreement with experimental data from time-resolved two-photon photoemission, angle-resolved photoelectron spectroscopy, and X-ray absorption fine structure measurements in the energy ranges 2–3.5, 10–15, and 60–100 eV, respectively.

  18. Can low energy electrons affect high energy physics accelerators?

    CERN Document Server

    Cimino, R; Furman, M A; Pivi, M; Ruggiero, F; Rumolo, Giovanni; Zimmermann, Frank

    2004-01-01

    The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at whic...

  19. Atomic excitation and molecular dissociation by low energy electron collisions

    International Nuclear Information System (INIS)

    Weyland, Marvin

    2016-01-01

    In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.

  20. Atomic excitation and molecular dissociation by low energy electron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Weyland, Marvin

    2016-11-16

    In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.

  1. Elastic scattering of low-energy electrons from ammonia

    International Nuclear Information System (INIS)

    Alle, D.T.; Gulley, R.J.; Buckman, S.J.; Brunger, M.J.

    1992-01-01

    We report absolute differential cross section measurements for vibrationally elastic electron scattering from NH 3 at incident energies from 2-30 eV. The present results, from a crossed electron-molecular beam apparatus, represent the first comprehensive experimental attempt to quantify the elastic electron-NH 3 scattering process. At each energy studied we have integrated our differential cross section data to generate total elastic and elastic momentum transfer cross sections and a critical comparison of both our differential and integral cross sections against previous experiment and theory is provided. We also report our observation of a strong Feshbach resonance in the elastic channel at an energy of 5.59 ± 0.05 eV. (Author)

  2. Beam line design for a low energy electron beam

    International Nuclear Information System (INIS)

    Arvind Kumar; Mahadevan, S.

    2002-01-01

    The design of a beam line for transport of a 70 keV electron beam from a thermionic gun to the Plane Wave Transformer (PWT) linac incorporating two solenoid magnets, a beam profile monitor and drift sections is presented. We used beam dynamics codes EGUN, PARMELA and compare simulated results with analytical calculations. (author)

  3. Examination of Graphene in a Scanning Low Energy Electron Microscope

    Czech Academy of Sciences Publication Activity Database

    Müllerová, Ilona; Mikmeková, Eliška; Frank, Luděk

    2015-01-01

    Roč. 21, S3 (2015), s. 29-30 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : graphene * LEEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  4. Low-energy electron transmission through high aspect ratio Al O nanocapillaries

    DEFF Research Database (Denmark)

    Milosavljević, A.R.; Jureta, J.; Víkor, G.

    2009-01-01

    Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined with resp......Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined...

  5. Method for controlling low-energy high current density electron beams

    International Nuclear Information System (INIS)

    Lee, J.N.; Oswald, R.B. Jr.

    1977-01-01

    A method and an apparatus for controlling the angle of incidence of low-energy, high current density electron beams are disclosed. The apparatus includes a current generating diode arrangement with a mesh anode for producing a drifting electron beam. An auxiliary grounded screen electrode is placed between the anode and a target for controlling the average angle of incidence of electrons in the drifting electron beam. According to the method of the present invention, movement of the auxiliary screen electrode relative to the target and the anode permits reliable and reproducible adjustment of the average angle of incidence of the electrons in low energy, high current density relativistic electron beams

  6. Plant height revertants of Dominant Semidwarf mutant rice created by low-energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Binmei [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wu Yuejin [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)], E-mail: yjwu@ipp.ac.cn; Xu Xue; Song, M.; Zhao, M. [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Fu, X.D. [Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101 (China)

    2008-04-15

    Dominant Semidwarf mutant rice (Sdd) was obtained from its wild type (WT) by irradiation with a low-energy ion beam. Six tall revertants of Sdd were induced by irradiation. The revertants restored the plant height to that of WT plants. Investigation of the agronomic character and genetic analysis indicate that the revertants are similar to WT plants with putative different inherited mutations. The revertants were checked for DNA differences using the simple sequence repeat technique. Among 408 such primers used, only 2 primers detected mutation sites in the revertants, which provided the molecular evidence for the revertants induced from Sdd. This study indicates that ion irradiation may be used as a mutagen to create revertants for plant architecture studies and could be a new application.

  7. Glass-like, low-energy excitations in neutron-irradiated quartz

    International Nuclear Information System (INIS)

    Gardner, J.W.

    1980-01-01

    The specific heat and thermal conductivity of neutron-irradiated crystalline quartz have been measured for temperatures approx. = 0.1 to 5 K. Four types of low-energy excitations are observed in the irradiated samples, two of which can be removed selectively by heat treatment. One set of remaining excitations gives rise to low-temperature thermal behavior characteristic of glassy (amorphous) solids. The density of these glass-like excitations can be 50% the density observed in vitreous silica, yet the sample still retains long-range atomic order. In a less-irradiated sample, glass-like excitations may be present with a density only approx. = 2.5% that observed in vitreous silica and possess a similar broad energy spectrum over 0.1 to 1 K

  8. Novel approaches to study low-energy electron-induced damage to DNA oligonucleotides

    International Nuclear Information System (INIS)

    Rackwitz, Jenny; Bald, Ilko; Ranković, Miloš Lj; Milosavljević, Aleksandar R

    2015-01-01

    The novel approach of DNA origami structures as templates for precise quantification of various well- defined oligonucleotides provides the opportunity to determine the sensitivity of complex DNA sequences towards low-energy electrons. (paper)

  9. Precision shape modification of nanodevices with a low-energy electron beam

    Science.gov (United States)

    Zettl, Alex; Yuzvinsky, Thomas David; Fennimore, Adam

    2010-03-09

    Methods of shape modifying a nanodevice by contacting it with a low-energy focused electron beam are disclosed here. In one embodiment, a nanodevice may be permanently reformed to a different geometry through an application of a deforming force and a low-energy focused electron beam. With the addition of an assist gas, material may be removed from the nanodevice through application of the low-energy focused electron beam. The independent methods of shape modification and material removal may be used either individually or simultaneously. Precision cuts with accuracies as high as 10 nm may be achieved through the use of precision low-energy Scanning Electron Microscope scan beams. These methods may be used in an automated system to produce nanodevices of very precise dimensions. These methods may be used to produce nanodevices of carbon-based, silicon-based, or other compositions by varying the assist gas.

  10. Low energy electron beam processing in Europe at the end of the 20th century

    International Nuclear Information System (INIS)

    Lauppi, U.V.

    1999-01-01

    Overview of low energy electron beam processing in Europe was presented. The presentation contained the following topics: the early installations, years of growth, stagnation, status 1999 and the future of this technology

  11. Studies on low energy ion-atom collisions by means of electron-spectroscopy

    International Nuclear Information System (INIS)

    Hirosi Suzuki

    1991-01-01

    The typical results of studies on autoionization processes produced by low energy ion-atom collisions are given by means of the ejected electron spectroscopy, which have been performed by Atomic Physics Group of Sophia University

  12. New insights in low-energy electron-fullerene interactions

    Science.gov (United States)

    Msezane, Alfred Z.; Felfli, Zineb

    2018-03-01

    The robust Regge-pole methodology has been used to probe for long-lived metastable anionic formation in Cn (n = 20, 24, 26, 28, 44, 70, 92 and 112) through the calculated electron elastic scattering total cross sections (TCSs). All the TCSs are found to be characterized by Ramsauer-Townsend minima, shape resonances and dramatically sharp resonances manifesting metastable anionic formation during the collisions. The energy positions of the anionic ground states resonances are found to match the measured electron affinities (EAs). We also investigated the size-effect through the correlation and polarization induced metastable resonances as the fullerene size varied from C20 through C112. The C20 TCSs exhibit atomic behavior while the C112 TCSs demonstrate strong departure from atomic behavior attributed to the size effect. Surprisingly C24 is found to have the largest EA among the investigated fullerenes making it suitable for use in organic solar cells and nanocatalysis.

  13. Low energy elastic electron scattering from polyatomic targets

    International Nuclear Information System (INIS)

    Khakoo, M A

    2008-01-01

    New differential cross-section measurements for elastic electron scattering from ethylene (C 2 H 4 ), three primary alcohols, methanol (CH 3 OH), ethanol (C 2 H 5 OH) and propanol (C 3 H 7 OH) are reported. The measurements are obtained using the relative flow method with a thin aperture as the collimating target gas source. The relative flow method is applied without the molecular diameters restriction imposed by the relative flow pressure condition on helium (the calibrating gas) and the unknown gases (the primary alcohols). The experimental data were taken at incident electron energies of 1eV, 2eV, 5eV, 10eV, 15eV, 20eV, 30eV, 50eV and 100eV, but only a brief survey of these results will be made here. The experimental results are compared to theoretical differential cross-sections are obtained by using the variational multi-channel Schwinger method. Initial comparisons between theory and experiment show that present theory is well-able to model low electron scattering from these polyatomic targets.

  14. Self-organization processes and nanocluster formation in crystal lattices by low-energy ion irradiation

    International Nuclear Information System (INIS)

    Tereshko, I.; Abidzina, V.; Tereshko, A.; Glushchenko, V.; Elkin, I.

    2007-01-01

    The goal of this paper is to study self-organization processes that cause nanostructural evolution in nonlinear crystal media. The subjects of the investigation were nonlinear homogeneous and heterogeneous atom chains. The method of computer simulation was used to investigate the interaction between low-energy ions and crystal lattices. It was based on the conception of three-dimensional lattice as a nonlinear atom chain system. We showed that that in homogeneous atom chains critical energy needed for self-organization processes development is less than for nonlinear atom chain with already embedded clusters. The possibility of nanostructure formation was studied by a molecular dynamics method of nonlinear oscillations in atomic oscillator systems of crystal lattices after their low-energy ion irradiation. (authors)

  15. Formation of nanostructures on HOPG surface in presence of surfactant atom during low energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, M., E-mail: ranjanm@ipr.res.in; Joshi, P.; Mukherjee, S.

    2016-07-15

    Low energy ions beam often develop periodic patterns on surfaces under normal or off-normal incidence. Formation of such periodic patterns depends on the substrate material, the ion beam parameters, and the processing conditions. Processing conditions introduce unwanted contaminant atoms, which also play strong role in pattern formation by changing the effective sputtering yield of the material. In this work we have analysed the effect of Cu, Fe and Al impurities introduced during low energy Ar{sup +} ion irradiation on HOPG substrate. It is observed that by changing the species of foreign atoms the surface topography changes drastically. The observed surface topography is co-related with the modified sputtering yield of HOPG. Presence of Cu and Fe amplify the effective sputtering yield of HOPG, so that the required threshold for the pattern formation is achieved with the given fluence, whereas Al does not lead to any significant change in the effective yield and hence no pattern formation occurs.

  16. Low-energy positron and electron scattering from nitrogen dioxide

    International Nuclear Information System (INIS)

    Chiari, Luca; Brunger, M J; Zecca, Antonio; García, Gustavo; Blanco, Francisco

    2013-01-01

    Total cross section (TCS) measurements for positron scattering from nitrogen dioxide (NO 2 ) are presented in the energy range 0.2–40 eV. The TCS, the elastic integral and differential cross sections, and the integral cross section accounting of all the inelastic processes (including positronium formation) have also been computed using the independent atom model with screening corrected additivity rule (IAM-SCAR) for incident energies from 1 to 1000 eV. A qualitative level of agreement is found between the present TCS experiment and theory at the common energies. As no previous measurements or calculations for positron–NO 2  scattering exist in the literature, we also computed the TCS for electron collisions with NO 2  employing the IAM-SCAR method. A comparison of those results to the present positron cross sections and the earlier electron-impact data and calculations is provided. To investigate the role that chemical substitution plays in positron scattering phenomena, we also compare the present positron–NO 2  data with the TCSs measured at the University of Trento for positron scattering from N 2 O and CO 2 . (paper)

  17. Electrophoresis examination of strand breaks in plasmid DNA induced by low-energy nitrogen ion irradiation

    International Nuclear Information System (INIS)

    Zhao Yong; Tan Zheng; Du Yanhua; Qiu Guanying

    2003-01-01

    To study the effect on plasmid DNA of heavy ion in the energy range of keV where nuclear stopping interaction becomes more important or even predominant, thin film of plasmid pGEM-3Zf(-) DNA was prepared on aluminum surface and irradiated in vacuum ( -3 Pa) by low-energy nitrogen ions with energy of 30 keV (LET=285 keV/μm) at various fluence ranging from 2 x 10 10 to 8.2 x 10 13 ions/cm 2 . DNA strand breaks were analyzed by neutral electrophoresis followed by quantification with image analysis software. Low-energy nitrogen ion irradiation induced single-, double- and multiple double-strand breaks (DSB) and multiple DSB as the dominating form of DNA damages. Moreover, the linear fluence-response relationship at a low fluence range suggests that DSBs are induced predominantly by single ion track. However, strand break production is limited to a short range in the irradiated samples

  18. RF emittance in a low energy electron linear accelerator

    Science.gov (United States)

    Sanaye Hajari, Sh.; Haghtalab, S.; Shaker, H.; Kelisani, M. Dayyani

    2018-04-01

    Transverse beam dynamics of an 8 MeV low current (10 mA) S-band traveling wave electron linear accelerator has been studied and optimized. The main issue is to limit the beam emittance, mainly induced by the transverse RF forces. The linac is being constructed at Institute for Research in Fundamental Science (IPM), Tehran Iran Labeled as Iran's First Linac, nearly all components of this accelerator are designed and constructed within the country. This paper discusses the RF coupler induced field asymmetry and the corresponding emittance at different focusing levels, introduces a detailed beam dynamics design of a solenoid focusing channel aiming to reduce the emittance growth and studies the solenoid misalignment tolerances. In addition it has been demonstrated that a prebuncher cavity with appropriate parameters can help improving the beam quality in the transverse plane.

  19. Electrostatic electron cyclotron waves generated by low-energy electron beams

    Czech Academy of Sciences Publication Activity Database

    Menietti, J. D.; Santolík, Ondřej; Scudder, J. D.; Pickett, J. S.; Gurnett, D. A.

    2002-01-01

    Roč. 107, A10, 1285 (2002), s. SMP 8-1-8-11, doi: 10.1029/2001JA009223 ISSN 0148-0227 R&D Projects: GA ČR GA205/01/1064 Grant - others:NASA(US) NAG5-7943; NASA(US) NAG5-9561; NASA(US) NAG5-8119 Institutional research plan: CEZ:AV0Z3042911; CEZ:MSM 113200004 Keywords : low-energy electron beams * cyclotron frequency Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.245, year: 2002

  20. Electron beam irradiating device

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, K

    1969-12-20

    The efficiency of an electron beam irradiating device is heightened by improving the irradiation atmosphere and the method of cooling the irradiation window. An irradiation chamber one side of which incorporates the irradiation windows provided at the lower end of the scanner is surrounded by a suitable cooling system such as a coolant piping network so as to cool the interior of the chamber which is provided with circulating means at each corner to circulate and thus cool an inert gas charged therewithin. The inert gas, chosen from a group of such gases which will not deleteriously react with the irradiating equipment, forms a flowing stream across the irradiation window to effect its cooling and does not contaminate the vacuum exhaust system or oxidize the filament when penetrating the equipment through any holes which the foil at the irradiation window may incur during the irradiating procedure.

  1. Low-energy electron collisions with metal clusters: Electron capture and cluster fragmentation

    International Nuclear Information System (INIS)

    Kresin, V.V.; Scheidemann, A.; Knight, W.D.

    1993-01-01

    The authors have carried out the first measurement of absolute cross sections for the interaction between electrons and size-resolved free metal clusters. Integral inelastic scattering cross sections have been determined for electron-Na n cluster collisions in the energy range from 0.1 eV to 30 eV. At energies ≤1 eV, cross sections increase with decreasing impact energies, while at higher energies they remain essentially constant. The dominant processes are electron attachment in the low-energy range, and collision-induced fragmentation at higher energies. The magnitude of electron capture cross sections can be quantitatively explained by the effect of the strong polarization field induced in the cluster by the incident electron. The cross sections are very large, reaching values of hundreds of angstrom 2 ; this is due to the highly polarizable nature of metal clusters. The inelastic interaction range for fragmentation collisions is also found to considerably exceed the cluster radius, again reflecting the long-range character of electron-cluster interactions. The important role played by the polarization interaction represents a bridge between the study of collision processes and the extensive research on cluster response properties. Furthermore, insight into the mechanisms of electron scattering is important for understanding production and detection of cluster ions in mass spectrometry and related processes

  2. The Role of Low-Energy (less than 20 eV) Electrons in Astrochemistry: A Tale of Two Molecules

    Science.gov (United States)

    Arumainayagam, Chris

    2016-07-01

    In the interstellar medium, UV photolysis of ice mantles encasing dust grains is thought to be the mechanism that drives the synthesis of "complex" molecules. The source of this reaction-initiating UV light is assumed to be local because externally-sourced UV radiation cannot pass through the ice-containing dark, dense molecular clouds. Externally sourced cosmic rays (E_{max} ˜10^{20} eV), in addition to producing UV light within these clouds, also produce large numbers of low-energy (≤ 20 eV) secondary electrons. The goal of our studies is to understand the low-energy electron-induced processes that occur when high-energy cosmic rays interact with interstellar ices. Using electron stimulated desorption (ESD), post-irradiation temperature-programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS), we have investigated the radiolysis initiated by electrons in condensed methanol and ammonia at ˜90K under ultrahigh vacuum (1 × 10^{-9} Torr) conditions. We have identified fifteen low-energy electron-induced methanol radiolysis products, many of which have been previously identified as being formed by methanol UV photolysis in the interstellar medium. We have also found evidence for the electron-induced formation from ammonia of hydrazine (N_2 H_4), diazene (N_2 H_2), cyclotriazane/triazene (N_3 H_3) and triazane (N_3 H_5). We have investigated the reaction yields' dependence on film thickness, irradiation time, incident current, electron energy, and metal substrate. These results provide a basis from which we can begin to understand the mechanisms by which methanol and ammonia can form more complex species in cosmic ices. Studies such as ours may ultimately help us better understand the initial stages of the genesis of life.

  3. Interactions between low energy electrons and DNA: a perspective from first-principles simulations

    Science.gov (United States)

    Kohanoff, Jorge; McAllister, Maeve; Tribello, Gareth A.; Gu, Bin

    2017-09-01

    DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts with the interaction of radiation—either photons or swift ions—and the biological medium, which causes electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, and strand breaks in plasmid DNA in particular (Boudaiffa et al 2000 Science 287 1658-60). These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage. In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when

  4. Damage of DNA by Low Energy Electrons (< 3 eV)

    International Nuclear Information System (INIS)

    Bald, Ilko; Illenberger, Eugen; Kopyra, Janina

    2012-01-01

    Recent experiments on low energy electron attachment to DNA and its components in the condensed phase and in the gas phase are reviewed and analysed. From different condensed phase experiments the sensitivity of DNA towards low energy electrons is well documented and strand breaks in DNA are observed at subexcitation energies (< 3 eV) and also in ultrafast electron transfer experiments involving electrons in presolvated states. Gas phase experiments indicate that all building blocks of DNA (the nucleobases, the sugar and the phosphate moiety) undergo resonant dissociative electron attachment (DEA) in the subexcitation regime which may ultimately lead to strand breaks. From very recent gas phase experiments on an entire nucleotide it can be concluded that most strand breaks result from direct electron attachment to the DNA backbone, but also initial electron capture by the nucleobase following electron transfer to the backbone contributes.

  5. Success and prospects for low energy, self-shielded electron beam accelerators

    International Nuclear Information System (INIS)

    Laeuppi, U.V.

    1988-01-01

    The advantages of self-shielded, low energy, electron beam accelerators for electron beam processing are described. Applications of these accelerators for cross-linking plastic films, drying of coated materials and printing inks and for curing processes are discussed. (U.K.)

  6. A method of imaging ultrathin foils with very low energy electrons

    Czech Academy of Sciences Publication Activity Database

    Müllerová, Ilona; Hovorka, Miloš; Frank, Luděk

    2012-01-01

    Roč. 119, AUG (2012), s. 79-81 ISSN 0304-3991 R&D Projects: GA AV ČR IAA100650902; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : very low energy STEM * penetration of very slow electrons * graphene Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.470, year: 2012

  7. Levels of 2-dodecylcyclobutanone in ground beef patties irradiated by low-energy X-ray and gamma rays.

    Science.gov (United States)

    Hijaz, Faraj M; Smith, J Scott

    2010-01-01

    Food irradiation improves food safety and maintains food quality by controlling microorganisms and extending shelf life. However, acceptance and commercial adoption of food irradiation is still low. Consumer groups such as Public Citizen and the Food and Water Watch have opposed irradiation because of the formation of 2-alkylcyclobutanones (2-ACBs) in irradiated, lipid-containing foods. The objectives of this study were to measure and to compare the level of 2-dodecylcyclobutanone (2-DCB) in ground beef irradiated by low-energy X-rays and gamma rays. Beef patties were irradiated by low-energy X-rays and gamma rays (Cs-137) at 3 targeted absorbed doses of 1.5, 3.0, and 5.0 kGy. The samples were extracted with n-hexane using a Soxhlet apparatus, and the 2-DCB concentration was determined with gas chromatography-mass spectrometry. The 2-DCB concentration increased linearly (P irradiation dose for gamma-ray and low-energy X-ray irradiated patties. There was no significant difference in 2-DCB concentration between gamma-ray and low-energy X-ray irradiated patties (P > 0.05) at all targeted doses. © 2010 Institute of Food Technologists®

  8. Chemical effects of low-energy electron impact on hydrocarbons in the gas phase. II. Propene

    International Nuclear Information System (INIS)

    Derai, R.; Danon, J.

    1977-01-01

    The chemical effects of low-energy (3.5 to 15.0 eV) electron impact on propene were investigated. The setup used for the irradiations has previously been described. Appearance curves for stable products were determined, from which correlations between products and precursors were deduced. In the excitation range, the main precursors are the triplet state at 4.4 eV and various singlet states around 7.0 and 9.0 eV. Above the ionization potential, contribution from superexcited molecules and ions was noted. Superexcited molecules are formed with a much higher cross section than excited molecules. A reaction scheme was proposed to account for the chemical effects associated with excited states and the yields of excited molecules in dissociating states were derived from experimental data. Results concerning the fragmentation of propene excited in singlet states conform to photolysis data. The following new results were obtained: the decomposition of propene excited in the triplet state at 4.4 eV involves mainly C--C bond rupture; the decomposition processes of superexcited and excited molecules are similar. A higher degree of fragmentation is observed in the case of superexcited molecules

  9. The effect of low energy helium ion irradiation on tungsten-tantalum (W-Ta) alloys under fusion relevant conditions

    Science.gov (United States)

    Gonderman, S.; Tripathi, J. K.; Novakowski, T. J.; Sizyuk, T.; Hassanein, A.

    2017-08-01

    Currently, tungsten remains the best candidate for plasma-facing components (PFCs) for future fusion devices because of its high melting point, low erosion, and strong mechanical properties. However, continued investigation has shown tungsten to undergo severe morphology changes under fusion-like conditions. These results motivate the study of innovative PFC materials which are resistant to surface morphology evolution. The goal of this work is to examine tungsten-tantalum (W-Ta) alloys, a potential PFC material, and their response to low energy helium ion irradiation. Specifically, W-Ta samples are exposed to 100 eV helium irradiations with a flux of 1.15 × 1021 ions m-2 s-1, at 873 K, 1023 K, and 1173 K for 1 h duration. Scanning electron microscopy (SEM) reveals significant changes in surface deterioration due to helium ion irradiation as a function of both temperature and tantalum concentration in W-Ta samples. X-Ray Diffraction (XRD) studies show a slight lattice parameter expansion in W-Ta alloy samples compared to pure W samples. The observed lattice parameter expansion in W-Ta alloy samples (proportional to increasing Ta wt.% concentrations) reflect significant differences observed in the evolution of surface morphology, i.e., fuzz development processes for both increasing Ta wt.% concentration and target temperature. These results suggest a correlation between the observed morphology differences and the induced crystal structure change caused by the presence of tantalum. Shifts in the XRD peaks before and after 100 eV helium irradiation with a flux of 1.15 × 1021 ions m-2 s-1, 1023 K, for 1 h showed a significant difference in the magnitude of the shift. This has suggested a possible link between the atomic spacing of the material and the accumulated damage. Ongoing research is needed on W-Ta alloys and other innovative materials for their application as irradiation resistant materials in future fusion or irradiation environments.

  10. Polymer surfaces graphitization by low-energy He{sup +} ions irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Geworski, A.; Lazareva, I.; Gieb, K.; Koval, Y.; Müller, P. [Department of Physics, Universität Erlangen-Nürnberg, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany)

    2014-08-14

    The electrical and optical properties of surfaces of polyimide and AZ5214e graphitized by low-energy (1 keV) He{sup +} irradiation at different polymer temperatures were investigated. The conductivity of the graphitized layers can be controlled with the irradiation temperature within a broad range and can reach values up to ∼1000 S/cm. We show that the electrical transport in low-conducting samples is governed by thermally activated hopping, while the samples with a high conductivity show a typical semimetallic behavior. The transition from thermally activated to semimetallic conductance governed by the irradiation temperature could also be observed in optical measurements. The semimetallic samples show an unusually high for graphitic materials carrier concentration, which results in a high extinction coefficient in the visible light range. By analyzing the temperature dependence of the conductance of the semimetallic samples, we conclude that the scattering of charge carriers is dominated by Coulomb interactions and can be described by a weak localization model. The transition from a three to two dimensional transport mechanism at low temperatures consistently explains the change in the temperature dependence of the conductance by cooling, observed in experiments.

  11. Generation and transportation of low-energy, high-current electron beams

    International Nuclear Information System (INIS)

    Ozur, G.E.; Proskurovskij, D.I.; Nazarov, D.S.

    1996-01-01

    Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm 2 , which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs

  12. Generation and transportation of low-energy, high-current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Ozur, G E; Proskurovskij, D I; Nazarov, D S [Russian Academy of Sciences, Tomsk (Russian Federation). Institute of High Current Electronics

    1997-12-31

    Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm{sup 2}, which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs.

  13. Tuning surface porosity on vanadium surface by low energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Hassanein, A.

    2016-08-15

    Highlights: • Surface nanostructuring on vanadium surface using novel He{sup +} ion irradiation process. • Tuning surface-porosity using high-flux, low-energy He{sup +} ion irradiation at constant elevated sample temperature (823–173 K). • Presented top-down approach guarantees good contact between different crystallites. • Sequential significant enhancement in surface-pore edge size (and corresponding reduction in surface-pore density) with increasing sample temperature. - Abstract: In the present study, we report on tuning the surface porosity on vanadium surfaces using high-flux, low-energy He{sup +} ion irradiation as function of sample temperature. Polished, mirror-finished vanadium samples were irradiated with 100 eV He{sup +} ions at a constant ion-flux of 7.2 × 10{sup 20} ions m{sup −2} s{sup −1} for 1 h duration at constant sample temperatures in the wide range of 823–1173 K. Our results show that the surface porosity of V{sub 2}O{sub 5} (naturally oxidized vanadium porous structure, after taking out from UHV) is strongly correlated to the sample temperature and is highly tunable. In fact, the surface porosity significantly increases with reducing sample temperature and reaches up to ∼87%. Optical reflectivity on these highly porous V{sub 2}O{sub 5} surfaces show ∼0% optical reflectivity at 670 nm wavelength, which is very similar to that of “black metal”. Combined with the naturally high melting point of V{sub 2}O{sub 5}, this very low optical reflectivity suggests potential application in solar power concentration technology. Additionally, this top-down approach guarantees relatively good contact between the different crystallites and avoids electrical conductivity limitations (if required). Since V{sub 2}O{sub 5} is naturally a potential photocatalytic material, the resulting sub-micron-sized cube-shaped porous structures could be used in solar water splitting for hydrogen production in energy applications.

  14. An optical study of multiple NEIAL events driven by low energy electron precipitation

    Directory of Open Access Journals (Sweden)

    J. M. Sullivan

    2008-08-01

    Full Text Available Optical data are compared with EISCAT radar observations of multiple Naturally Enhanced Ion-Acoustic Line (NEIAL events in the dayside cusp. This study uses narrow field of view cameras to observe small-scale, short-lived auroral features. Using multiple-wavelength optical observations, a direct link between NEIAL occurrences and low energy (about 100 eV optical emissions is shown. This is consistent with the Langmuir wave decay interpretation of NEIALs being driven by streams of low-energy electrons. Modelling work connected with this study shows that, for the measured ionospheric conditions and precipitation characteristics, growth of unstable Langmuir (electron plasma waves can occur, which decay into ion-acoustic wave modes. The link with low energy optical emissions shown here, will enable future studies of the shape, extent, lifetime, grouping and motions of NEIALs.

  15. Ultra-low energy electrons from fast heavy-ion helium collisions: the `target Cusp`

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, W. [Freiburg Univ. (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Moshammer, R.; Kollmus, H.; Ullrich, J. [Freiburg Univ. (Germany); O`Rourke, F.S.C. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom); Sarkadi, L. [Magyar Tudomanyos Akademia, Debrecen (Hungary). Atommag Kutato Intezete; Mann, R. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Hagmann, S. [Kansas State Univ., Manhattan, KS (United States). J.R. MacDonald Lab.; Olson, R.E. [Missouri Univ., Rolla, MO (United States). Dept. of Physics

    1998-09-01

    Doubly differential cross sections d{sup 2}{sigma}/dv {sub parallel} dv {sub perpendicular} {sub to} have been obtained by mapping the 3-dimensional velocity space of ultra-low and low-energy electrons (1.5 meV{<=} E{sub e}{<=}100 eV) emitted in singly ionizing 3.6 MeV/u Au{sup 53+} on helium collisions. A sharp ({Delta}E{sub e} {sub perpendicular} {sub to} {sup FWHM} {<=} 22 meV) asymmetric peak centered at vertical stroke anti {nu} vertical stroke =0 is observed to emerge at ultra-low energies from the strongly forward shifted low-energy electron velocity distribution. The shape of this ``target cusp``, which is very sensitive on the details of the two-center potential, is in excellent accord with theoretical CTMC and CDW-EIS predictions. (orig.)

  16. Before the Ring: synthesis of linear organic molecules in astrophysical ices by low energy electron impact

    Science.gov (United States)

    Huels, Michael A.; Bass Andrew, D.; Mirsaleh-Kohan, Nasrin; Sanche, Leon

    The question of the origin for the building blocks of life, either synthesized here on earth, or in space [1], has been the subject of much debate, experimental investigation, or astronomical observation, much of it stimulated by the early experiments of Miller [2], and subsequent space radiation related variations thereof [3-5]. And while the precise details of the formation of even the simplest biomolecules that make up life on earth still remain shrouded inmystery, one of the notions that persist throughout the debate is that the building blocks of life, such as amino-acids, or even the cyclic components of RNA and DNA, or other cyclic hydrocarbons (e.g. PHAs), where synthesized via radiolysis [6] either in the earths proto-atmosphere, its early oceans, or in the near interstellar space surrounding the early earth. Here we provide experimental evidence for the hypothesis that interactions of low energy secondary electrons and ions, formed during the radiolysis of matter, with atoms and molecules in the medium, may have played, and may still play an important role in the chemical transformation of astrophysical or planetary surface ices [7], where they lead to the synthesis of more complex chemical species from less complex, naturally occurring components. We report the synthesis and desorption of new chemical species from simple molecular surface ices, containing CH4 / CD4 , C2 D2 , O2 , CO, CO2 , or N2 in various combination mixtures, irradiated by low energy (CO+ (n = 1-3), among others. The formation of all these linear, pre-biotic molecular species, produced here by electron initiated cation-reactions in simple molecular films, suggests that similar mechanisms likely precede the synthesis of life's most basic cyclic molecular components in planetary, or astrophysical surface ices that are continuously subjected to the types of space radiations (UV, X-or -ray, or heavy ions) that can generate such low energy secondary electrons. [Funded by NSERC and Canadian

  17. Temperature-dependent surface modification of Ta due to high-flux, low-energy He+ ion irradiation

    International Nuclear Information System (INIS)

    Novakowski, T.J.; Tripathi, J.K.; Hassanein, A.

    2015-01-01

    This work examines the response of Tantalum (Ta) as a potential candidate for plasma-facing components (PFCs) in future nuclear fusion reactors. Tantalum samples were exposed to high-flux, low-energy He + ion irradiation at different temperatures in the range of 823–1223 K. The samples were irradiated at normal incidence with 100 eV He + ions at constant flux of 1.2 × 10 21 ions m −2  s −1 to a total fluence of 4.3 × 10 24 ions m −2 . An additional Ta sample was also irradiated at 1023 K using a higher ion fluence of 1.7 × 10 25 ions m −2 (at the same flux of 1.2 × 10 21 ions m −2  s −1 ), to confirm the possibility of fuzz formation at higher fluence. This higher fluence was chosen to roughly correspond to the lower fluence threshold of fuzz formation in Tungsten (W). Surface morphology was characterized with a combination of field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). These results demonstrate that the main mode of surface damage is pinholes with an average size of ∼70 nm 2 for all temperatures. However, significantly larger pinholes are observed at elevated temperatures (1123 and 1223 K) resulting from the agglomeration of smaller pinholes. Ex situ X-ray photoelectron spectroscopy (XPS) provides information about the oxidation characteristics of irradiated surfaces, showing minimal exfoliation of the irradiated Ta surface. Additionally, optical reflectivity measurements are performed to further characterize radiation damage on Ta samples, showing gradual reductions in the optical reflectivity as a function of temperature.

  18. Evaluation and application of the low energy electron emitter 161Tb

    International Nuclear Information System (INIS)

    Lehenberger, Silvia M.

    2010-01-01

    The low energy electron emitter 161 Tb was produced n.c.a. in quantities sufficient for therapeutic applications and successfully used for labeling of peptides and antibodies. Furthermore, these compounds have been compared to n.c.a. 177 Lu labeled mAbs via cell experiments, a radionuclide that is already used in clinical nuclear oncology.

  19. Low-energy electron scattering by C, N, and O atoms

    Energy Technology Data Exchange (ETDEWEB)

    Nesbet, R K [International Business Machines Corp., San Jose, Calif. (USA). Research Lab.

    1977-07-01

    Recent theoretical studies of low-energy electron scattering by C, N, and O atoms are reviewed and results are compared with available experimental data. A critical comparison is made of the two principal methods used in this work-polarized pseudostate expansion with R-matrix computations or direct integration, and Bethe-Goldstone expansion with matrix variational computations. 31 references.

  20. Low energy electronic scattering processes in the topological Weyl semimetal TaAs

    Energy Technology Data Exchange (ETDEWEB)

    Muellner, Silvia; Lemmens, Peter [IPKM, TU-BS, Braunschweig (Germany); Gnezdilov, Vladimir [IPKM, TU-BS, Braunschweig (Germany); ILTPE NAS (Ukraine); Sankar, Raman; Chou, Fangcheng [CCMS, National Taiwan Univ., Taipei (China)

    2016-07-01

    The topological Weyl semimetal TaAs shows Weyl points as well as topological surface states (Fermi arcs) intimately related to symmetry and strong spin orbit interaction. We find evidence for a low energy maximum in the scattering intensity that is compatible with electronic correlations in a collision dominated regime. We compare our observations with topological insulators.

  1. Low-energy electron scattering from pyrimidine: Similarities and differences with benzene

    Science.gov (United States)

    Jones, D. B.; Bellm, S. M.; Limão-Vieira, P.; Brunger, M. J.

    2012-05-01

    Differential cross sections for low-energy electron-impact excitation of the unresolved combinations of 23B2 + 21A1 and 31A1 + 21B2 electronic states of pyrimidine are reported. Comparisons are made with recent differential cross section measurements for the electron-impact excitation of the 1E1u and unresolved 1B1u + 3E2g electronic states of benzene [H. Kato, M. Hoshino, H. Tanaka, P. Limão-Vieira, O. Ingolfsson, L. Campbell, M.J. Brunger, J. Chem. Phys. 134 (2011) 134308.], in order to evaluate the nature of electron impact π-π∗ transitions in aromatic species.

  2. Growth and intercalation of graphene on silicon carbide studied by low-energy electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Speck, Florian; Ostler, Markus; Wanke, Martina; Seyller, Thomas [Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Technische Physik, Erlangen (Germany); Technische Universitaet Chemnitz, Institut fuer Physik (Germany); Besendoerfer, Sven [Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Technische Physik, Erlangen (Germany); Krone, Julia [Technische Universitaet Chemnitz, Institut fuer Physik (Germany)

    2017-11-15

    Based on its electronic, structural, chemical, and mechanical properties, many potential applications have been proposed for graphene. In order to realize these visions, graphene has to be synthesized, grown, or exfoliated with properties that are determined by the targeted application. Growth of so-called epitaxial graphene on silicon carbide by sublimation of silicon in an argon atmosphere is one particular method that could potentially lead to electronic applications. In this contribution we summarize our recent work on different aspects of epitaxial graphene growth and interface manipulation by intercalation, which was performed by a combination of low-energy electron microscopy, low-energy electron diffraction, atomic force microscopy and photoelectron spectroscopy. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Direct Observation of Individual Charges and Their Dynamics on Graphene by Low-Energy Electron Holography.

    Science.gov (United States)

    Latychevskaia, Tatiana; Wicki, Flavio; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

    2016-09-14

    Visualizing individual charges confined to molecules and observing their dynamics with high spatial resolution is a challenge for advancing various fields in science, ranging from mesoscopic physics to electron transfer events in biological molecules. We show here that the high sensitivity of low-energy electrons to local electric fields can be employed to directly visualize individual charged adsorbates and to study their behavior in a quantitative way. This makes electron holography a unique probing tool for directly visualizing charge distributions with a sensitivity of a fraction of an elementary charge. Moreover, spatial resolution in the nanometer range and fast data acquisition inherent to lens-less low-energy electron holography allows for direct visual inspection of charge transfer processes.

  4. Ab initio study of dissociative attachment of low-energy electrons to F2

    International Nuclear Information System (INIS)

    Hazi, A.U.; Orel, A.E.; Rescigno, T.N.

    1981-01-01

    Adiabatic-nuclei resonance theory has been applied to the study of dissociative attachment of low-energy electrons to F 2 . Stieltjes moment theory was used to derive fixed-nuclei electronic resonance parameters from large scale configuration-interaction calculations on F 2 and F 2 - . Dissociative attachment cross sections are reported for the four lowest vibrational levels of F 2 and compared to available experimental data

  5. A study on the electric properties of single-junction GaAs solar cells under the combined radiation of low-energy protons and electrons

    International Nuclear Information System (INIS)

    Zhao Huijie; Wu Yiyong; Xiao Jingdong; He Shiyu; Yang Dezhuang; Sun Yanzheng; Sun Qiang; Lv Wei; Xiao Zhibin; Huang Caiyong

    2008-01-01

    Displacement damage induced by charged particle radiation is the main cause of degradation of orbital-service solar cells, while the radiation-induced ionization shows no permanent damage effect on their electrical properties. It is reported that in single crystal silicon solar cells, low-energy electron radiation does not exert permanent degradation of their properties, but the fluence of electron radiation exerts an influence on the damage magnitude under the combined radiation of protons and electrons. The electrical properties of the single-junction GaAs/Ge solar cells were investigated after irradiation by sequential and synchronous electron and proton beams. Low-energy electron radiation showed no effects on the change of the solar cell properties during sequential or synchronous irradiation, implying ionization during particle radiation could not exert influence on the displacement damage process to the solar cells under the experimental conditions

  6. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  7. Inelastic scattering of low-energy electrons in metals: the role of kinematics in screening

    International Nuclear Information System (INIS)

    Alducin, M.; Juaristi, J.I.; Nagy, I.; Echenique, P.M.

    2002-01-01

    The inelastic scattering of low-energy electrons with the mobile part of the electron density of free-electron-like materials is investigated. Based on the dielectric theory for the homogeneous electron gas, the concept of Bohm and Pines is adopted in order to separate the single-particle and collective basic channels of the total inelastic rate. An effective screened potential is introduced to describe the separated single-particle part. The role of the relative motion of electrons, a kind of dynamical correlation effect, is modelled in this potential via a physical argument. The results obtained show that the nontrivial correlated motion of electrons may have a measurable influence on the result of dynamical probing of a degenerate electron gas. (author)

  8. Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

    International Nuclear Information System (INIS)

    Figuera, Juan de la; Vergara, Lucía; N'Diaye, Alpha T.; Quesada, Adrian; Schmid, Andreas K.

    2013-01-01

    Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (001) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface directions, and domain wall structures include 90° and 180° walls. A type of unusually curved domain walls are interpreted as Néel-capped surface terminations of 180° Bloch walls. - Highlights: ► The (001) surface of magnetite is imaged by spin-polarized low-energy electron microscopy. ► The magnetic domain microstructure is resolved. ► Magnetic easy axes in this surface are found to be along directions. ► Magnetic domain wall structures include wide Néel-caps

  9. Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Figuera, Juan de la, E-mail: juan.delafiguera@iqfr.csic.es [Instituto de Química-Física “Rocasolano”, CSIC, Madrid 28006 (Spain); Vergara, Lucía [Instituto de Química-Física “Rocasolano”, CSIC, Madrid 28006 (Spain); N' Diaye, Alpha T. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Quesada, Adrian [Instituto de Cerámica y Vidrio, CSIC, Calle Kelsen 5, 28049, Madrid (Spain); Schmid, Andreas K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2013-07-15

    Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (001) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface <110> directions, and domain wall structures include 90° and 180° walls. A type of unusually curved domain walls are interpreted as Néel-capped surface terminations of 180° Bloch walls. - Highlights: ► The (001) surface of magnetite is imaged by spin-polarized low-energy electron microscopy. ► The magnetic domain microstructure is resolved. ► Magnetic easy axes in this surface are found to be along <110> directions. ► Magnetic domain wall structures include wide Néel-caps.

  10. Energy analyzer for Auger electron spectroscopy and low-energy backscattering ion spectroscopy

    International Nuclear Information System (INIS)

    Volkov, S.S.; Gorelik, V.A.; Gutenko, V.T.; Protopopov, O.D.; Trubitsin, A.A.; Shuvalova, Z.A.; Yakushev, G.A.

    1988-01-01

    Energy analyzer for electron Auger spectroscopy and low-energy backscattering ion spectroscopy is described. Analyzer presents one-cascade variant of cylindrical mirror with second-order focusing. Energy relative resolution is continuously adjusted within 0.2-1.2% limits. Signal/noise relation by Cu Auger-line at 1 muA current of exciting beam changes upper limit of range 150-450

  11. Low-energy electron point projection microscopy of suspended graphene, the ultimate 'microscope slide'

    International Nuclear Information System (INIS)

    Mutus, J Y; Livadaru, L; Urban, R; Salomons, M H; Cloutier, M; Wolkow, R A; Robinson, J T

    2011-01-01

    Point projection microscopy (PPM) is used to image suspended graphene by using low-energy electrons (100-205 eV). Because of the low energies used, the graphene is neither damaged nor contaminated by the electron beam for doses of the order of 10 7 electrons per nm 2 . The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet twice as thick as the covalent radius of sp 2 -bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to diffraction off the edge of a graphene knife edge is observed and is used to calculate a virtual source size of 4.7±0.6 A for the electron emitter. It is demonstrated that graphene can serve as both the anode and the substrate in PPM, thereby avoiding distortions due to strong field gradients around nanoscale objects. Graphene can be used to image objects suspended on the sheet using PPM and, in the future, electron holography.

  12. Low-energy particle experiments-electron analyzer (LEPe) onboard the Arase spacecraft

    Science.gov (United States)

    Kazama, Yoichi; Wang, Bo-Jhou; Wang, Shiang-Yu; Ho, Paul T. P.; Tam, Sunny W. Y.; Chang, Tzu-Fang; Chiang, Chih-Yu; Asamura, Kazushi

    2017-12-01

    In this report, we describe the low-energy electron instrument LEPe (low-energy particle experiments-electron analyzer) onboard the Arase (ERG) spacecraft. The instrument measures a three-dimensional distribution function of electrons with energies of ˜ 19 eV-19 keV. Electrons in this energy range dominate in the inner magnetosphere, and measurement of such electrons is important in terms of understanding the magnetospheric dynamics and wave-particle interaction. The instrument employs a toroidal tophat electrostatic energy analyzer with a passive 6-mm aluminum shield. To minimize background radiation effects, the analyzer has a background channel, which monitors counts produced by background radiation. Background counts are then subtracted from measured counts. Electronic components are radiation tolerant, and 5-mm-thick shielding of the electronics housing ensures that the total dose is less than 100 kRad for the one-year nominal mission lifetime. The first in-space measurement test was done on February 12, 2017, showing that the instrument functions well. On February 27, the first all-instrument run test was done, and the LEPe instrument measured an energy dispersion event probably related to a substorm injection occurring immediately before the instrument turn-on. These initial results indicate that the instrument works fine in space, and the measurement performance is good for science purposes.[Figure not available: see fulltext.

  13. Probing low-energy hyperbolic polaritons in van der Waals crystals with an electron microscope.

    Science.gov (United States)

    Govyadinov, Alexander A; Konečná, Andrea; Chuvilin, Andrey; Vélez, Saül; Dolado, Irene; Nikitin, Alexey Y; Lopatin, Sergei; Casanova, Fèlix; Hueso, Luis E; Aizpurua, Javier; Hillenbrand, Rainer

    2017-07-21

    Van der Waals materials exhibit intriguing structural, electronic, and photonic properties. Electron energy loss spectroscopy within scanning transmission electron microscopy allows for nanoscale mapping of such properties. However, its detection is typically limited to energy losses in the eV range-too large for probing low-energy excitations such as phonons or mid-infrared plasmons. Here, we adapt a conventional instrument to probe energy loss down to 100 meV, and map phononic states in hexagonal boron nitride, a representative van der Waals material. The boron nitride spectra depend on the flake thickness and on the distance of the electron beam to the flake edges. To explain these observations, we developed a classical response theory that describes the interaction of fast electrons with (anisotropic) van der Waals slabs, revealing that the electron energy loss is dominated by excitation of hyperbolic phonon polaritons, and not of bulk phonons as often reported. Thus, our work is of fundamental importance for interpreting future low-energy loss spectra of van der Waals materials.Here the authors adapt a STEM-EELS system to probe energy loss down to 100 meV, and apply it to map phononic states in hexagonal boron nitride, revealing that the electron loss is dominated by hyperbolic phonon polaritons.

  14. Probing low-energy hyperbolic polaritons in van der Waals crystals with an electron microscope

    KAUST Repository

    Govyadinov, Alexander A.

    2017-07-14

    Van der Waals materials exhibit intriguing structural, electronic, and photonic properties. Electron energy loss spectroscopy within scanning transmission electron microscopy allows for nanoscale mapping of such properties. However, its detection is typically limited to energy losses in the eV range-too large for probing low-energy excitations such as phonons or mid-infrared plasmons. Here, we adapt a conventional instrument to probe energy loss down to 100 meV, and map phononic states in hexagonal boron nitride, a representative van der Waals material. The boron nitride spectra depend on the flake thickness and on the distance of the electron beam to the flake edges. To explain these observations, we developed a classical response theory that describes the interaction of fast electrons with (anisotropic) van der Waals slabs, revealing that the electron energy loss is dominated by excitation of hyperbolic phonon polaritons, and not of bulk phonons as often reported. Thus, our work is of fundamental importance for interpreting future low-energy loss spectra of van der Waals materials.Here the authors adapt a STEM-EELS system to probe energy loss down to 100 meV, and apply it to map phononic states in hexagonal boron nitride, revealing that the electron loss is dominated by hyperbolic phonon polaritons.

  15. Probing low-energy hyperbolic polaritons in van der Waals crystals with an electron microscope

    KAUST Repository

    Govyadinov, Alexander A.; Konečná , Andrea; Chuvilin, Andrey; Vé lez, Saü l; Dolado, Irene; Nikitin, Alexey Y.; Lopatin, Sergei; Casanova, Fè lix; Hueso, Luis E.; Aizpurua, Javier; Hillenbrand, Rainer

    2017-01-01

    Van der Waals materials exhibit intriguing structural, electronic, and photonic properties. Electron energy loss spectroscopy within scanning transmission electron microscopy allows for nanoscale mapping of such properties. However, its detection is typically limited to energy losses in the eV range-too large for probing low-energy excitations such as phonons or mid-infrared plasmons. Here, we adapt a conventional instrument to probe energy loss down to 100 meV, and map phononic states in hexagonal boron nitride, a representative van der Waals material. The boron nitride spectra depend on the flake thickness and on the distance of the electron beam to the flake edges. To explain these observations, we developed a classical response theory that describes the interaction of fast electrons with (anisotropic) van der Waals slabs, revealing that the electron energy loss is dominated by excitation of hyperbolic phonon polaritons, and not of bulk phonons as often reported. Thus, our work is of fundamental importance for interpreting future low-energy loss spectra of van der Waals materials.Here the authors adapt a STEM-EELS system to probe energy loss down to 100 meV, and apply it to map phononic states in hexagonal boron nitride, revealing that the electron loss is dominated by hyperbolic phonon polaritons.

  16. High-sensitivity visualization of localized electric fields using low-energy electron beam deflection

    Science.gov (United States)

    Jeong, Samuel; Ito, Yoshikazu; Edwards, Gary; Fujita, Jun-ichi

    2018-06-01

    The visualization of localized electronic charges on nanocatalysts is expected to yield fundamental information about catalytic reaction mechanisms. We have developed a high-sensitivity detection technique for the visualization of localized charges on a catalyst and their corresponding electric field distribution, using a low-energy beam of 1 to 5 keV electrons and a high-sensitivity scanning transmission electron microscope (STEM) detector. The highest sensitivity for visualizing a localized electric field was ∼0.08 V/µm at a distance of ∼17 µm from a localized charge at 1 keV of the primary electron energy, and a weak local electric field produced by 200 electrons accumulated on the carbon nanotube (CNT) apex can be visualized. We also observed that Au nanoparticles distributed on a CNT forest tended to accumulate a certain amount of charges, about 150 electrons, at a ‑2 V bias.

  17. Preparation of {sup 114m}In low energy conversion electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Wrede, C., E-mail: wrede@uw.ed [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Filippone, B.W. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Garcia, A.; Harper, G.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Lassell, S. [Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Liu, J. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Mendenhall, M.P. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Palmer, A.S.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Pattie, R.W. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Will, D.I. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Young, A.R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2011-05-15

    Highlights: {yields} Controlled ion implantation of In-113 into thin Al substrate. {yields} Production of In-114m (half life = 50 days) by neutron irradiation. {yields} Use of In-114m as a source of electron lines and continuum for calibrations. {yields} Source reactivation by short neutron irradiation. -- Abstract: The preparation of {sup 114m}In sources of conversion electrons in the energy range 162-190 keV and {beta} continuum with a 1989 keV endpoint via ion implantation of {sup 113}In into Al substrates and subsequent irradiation by thermal and epi-thermal neutrons in a nuclear reactor is described.

  18. Preparation of 114mIn low energy conversion electron sources

    International Nuclear Information System (INIS)

    Wrede, C.; Filippone, B.W.; Garcia, A.; Harper, G.C.; Lassell, S.; Liu, J.; Mendenhall, M.P.; Palmer, A.S.C.; Pattie, R.W.; Will, D.I.; Young, A.R.

    2011-01-01

    Highlights: → Controlled ion implantation of In-113 into thin Al substrate. → Production of In-114m (half life = 50 days) by neutron irradiation. → Use of In-114m as a source of electron lines and continuum for calibrations. → Source reactivation by short neutron irradiation. -- Abstract: The preparation of 114m In sources of conversion electrons in the energy range 162-190 keV and β continuum with a 1989 keV endpoint via ion implantation of 113 In into Al substrates and subsequent irradiation by thermal and epi-thermal neutrons in a nuclear reactor is described.

  19. Preparation and mechanical properties of PLA-PEG copolymers modified by radiation-induced crosslinking of low energy electron beams

    International Nuclear Information System (INIS)

    Peikai Miao; Wenrui Tang; Ke Zeng; Yan Tang; Yipeng Wang; Hongfei Zhou; Ke Zhou; Tao Liu; Gang Yang

    2007-01-01

    PLA-PEG copolymer is wildly applied in medical and pharmaceutical fields, but its mechanical properties are not so good, such as the tensile intensity and elongation at break. To improve these properties, PLA-PEG copolymers were synthesized and irradiated using low energy electron beams (EB) with various irradiation doses in the presence of 3 wt% polyfunctional monomer (triallylcyanurate, TAC) as crosslinking agent to introduce crosslinking between polymer chains. It was found that with the increase of the irradiation doses, the tensile intensity of the PLA-PEG increased, while the elongation at break decreased, the most optimal irradiation dose was 80 kGy, the tensile intensity was 12.5 MPa and 19.9 MPa, corresponding to the elongation at break of 282.8 % and 28.7% for PLA9-PEG6 and PLA11-PEG6, respectively. Meanwhile, the solvent resistance of crosslinked sample was improved obviously at this dose. The crosslinked PLA-PEG copolymer can be applied to packaging materials, tubes and so on. (Author)

  20. Guiding of low-energy electrons by highly ordered Al2 O3 nanocapillaries

    DEFF Research Database (Denmark)

    Milosavljević, A.R.; Víkor, G.; Pešić, Z.D.

    2007-01-01

    We report an experimental study of guided transmission of low-energy (200-350 eV) electrons through highly ordered Al2 O3 nanocapillaries with large aspect ratio (140 nm diameter and 15 μm length). The nanochannel array was prepared using self-ordering phenomena during a two-step anodization...... process of a high-purity aluminum foil. The experimental results clearly show the existence of the guiding effect, as found for highly charged ions. The guiding of the electron beam was observed for tilt angles up to 12°. As seen for highly charged ions, the guiding efficiency increases with decreasing...

  1. Role of secondary low energy electrons in radiobiology and chemoradiation therapy of cancer

    Science.gov (United States)

    Sanche, Léon

    2009-05-01

    With the chemotherapeutic agent cisplatin bound to DNA, damage to the molecule by electrons of low and high energies increases by factors varying from 1.3 to 4.4. The enhancement in bond dissociation is triggered by modifications of the interaction of low energy electrons with DNA. From our understanding of the latter, the present Letter attempts to explain the basic radiation-damage mechanism responsible for the efficiency of the concomitant chemoradiation treatment of cancer. Such a basic comprehension of the direct effects of radiation may have implications in the design of new chemotherapeutic and radiosensitizing drugs, as well as in the development of more efficient protocols in chemoradiation therapy.

  2. Ab initio calculations on collisions of low energy electrons with polyatomic molecules

    International Nuclear Information System (INIS)

    Rescigno, T.N.

    1991-01-01

    The Kohn variational method is one of simplest, and oldest, techniques for performing scattering calculations. Nevertheless, a number of formal problems, as well as practical difficulties associated with the computation of certain required matrix elements, delayed its application to electron--molecule scattering problems for many years. This paper will describe the recent theoretical and computational developments that have made the ''complex'' Kohn variational method a practical tool for carrying out calculations of low energy electron--molecule scattering. Recent calculations on a number of target molecules will also be summarized. 41 refs., 7 figs

  3. Initial state dependence of low-energy electron emission in fast ion atom collisions

    International Nuclear Information System (INIS)

    Moshammer, R.; Schmitt, W.; Kollmus, H.; Ullrich, J.; Fainstein, P.D.; Hagmann, S.

    1999-06-01

    Single and multiple ionization of Neon and Argon atoms by 3.6 MeV/u Au 53+ impact has been explored in kinematically complete experiments. Doubly differential cross sections for low-energy electron emission have been obtained for defined charge state of the recoiling target ion and the receding projectile. Observed target specific structures in the electron continuum are attributable to the nodal structure of the initial bound state momentum distribution. The experimental data are in excellent accord with CDW-EIS single ionization calculations if multiple ionization is considered appropriately. (orig.)

  4. Ab initio study of low-energy electron collisions with ethylene

    International Nuclear Information System (INIS)

    Trevisan, C.S.; Orel, A.E.; Rescigno, T.N.

    2003-01-01

    We present the results of an investigation of elastic electron scattering by ethylene C 2 H 4 with incident electron energies ranging from 0.5 to 20 eV, using the complex Kohn variational method. These fully ab initio calculations accurately reproduce experimental angular differential cross sections at energies below 3 eV. Low-energy electron scattering by ethylene is sensitive to the inclusion of electronic correlation and target-distortion effects. We therefore report results that describe the dynamic polarization of the target by the incident electron and involve calculations over a range of different geometries, including the effects of nuclear motion in the resonant 2 B 2g symmetry with an adiabatic nuclei treatment of the C-C stretch mode. The inclusion of dynamic polarization and the effect of nuclear motion are equally critical in obtaining accurate results. The calculated cross sections are compared with recent experimental measurements

  5. Origin of the Differential Fluxes of Low-energy Electrons in the Inner Heliosheath

    Energy Technology Data Exchange (ETDEWEB)

    Fahr, H. J. [Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn (Germany); Krimigis, S. M. [Office of Space Research and Technology, Academy of Athens, 10679 Athens (Greece); Fichtner, H.; Scherer, K.; Sylla, A. [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, 44780 Bochum (Germany); Ferreira, S. E. S.; Potgieter, M. S., E-mail: hf@tp4.rub.de [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2017-10-10

    The study addresses the question of the origin of low-energy electrons measured by Voyager 1 in the multi-keV range in the inner heliosheath. It intends to demonstrate that the observed keV-fluxes of electrons are consistent with their transmission through the termination shock under the influence of the associated electrostatic field. A power-law representation of the electron velocity distribution just downstream of the solar wind termination shock is motivated and formulated in terms of a so-called κ -distribution function. From this initial function spectral electron fluxes in the range 40–70 keV are derived and compared to the data. It is shown that with κ -values between 7 and 8 the data can be satisfactorily explained. Given these comparatively high κ -values, it is concluded that the electron distribution just downstream of the termination shock relaxes toward but does not reach a Maxwellian shape in the inner heliosheath.

  6. Direct observations of low-energy solar electrons associated with a type 3 solar radio burst

    Science.gov (United States)

    Frank, L. A.; Gurnett, D. A.

    1972-01-01

    On 6 April 1971 a solar X-ray flare and a type 3 solar radio noise burst were observed with instrumentation on the eccentric-orbiting satellite IMP 6. The type 3 solar radio noise burst was detected down to a frequency of 31 kHz. A highly anisotropic packet of low-energy solar electron intensities arrived at the satellite approximately 6000 seconds after the onset of the solar flare. This packet of solar electron intensities was observed for 4200 seconds. Maximum differential intensities of the solar electrons were in the energy range of one to several keV. The frequency drift rate of the type 3 radio noise at frequencies below 178 kHz also indicated an average particle speed corresponding to that of a 3-keV electron. The simultaneous observations of these solar electron intensities and of the type 3 solar radio burst are presented, and their interrelationships are explored.

  7. Electron irradiation of zeolites

    International Nuclear Information System (INIS)

    Wang, S.X.; Wang, L.M.; Ewing, R.C.

    1999-01-01

    Three different zeolites (analcime, natrolite, and zeolite-Y) were irradiated with 200 keV and 400 keV electrons. All zeolites amorphized under a relatively low electron fluence. The transformation from the crystalline-to-amorphous state was continuous and homogeneous. The electron fluences for amorphization of the three zeolites at room temperature were: 7.0 x 10 19 e - /cm 2 (analcime), 1.8 x 10 20 e - /cm 2 (natrolite), and 3.4 x 10 20 e - /cm 2 (zeolite-Y). The different susceptibilities to amorphization are attributed to the different channel sizes in the structures which are the pathways for the release of water molecules and Na + . Natrolite formed bubbles under electron irradiation, even before complete amorphization. Analcime formed bubbles after amorphization. Zeolite-Y did not form bubbles under irradiation. The differences in bubble formation are attributed to the different channel sizes of the three zeolites. The amorphization dose was also measured at different temperatures. An inverse temperature dependence of amorphization dose was observed for all three zeolites: electron dose for amorphization decreased with increasing temperature. This unique temperature effect is attributed to the fact that zeolites are thermally unstable. A semi-empirical model was derived to describe the temperature effect of amorphization in these zeolites

  8. The low-energy β(-) and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy.

    Science.gov (United States)

    Lehenberger, Silvia; Barkhausen, Christoph; Cohrs, Susan; Fischer, Eliane; Grünberg, Jürgen; Hohn, Alexander; Köster, Ulli; Schibli, Roger; Türler, Andreas; Zhernosekov, Konstantin

    2011-08-01

    The low-energy β(-) emitter (161)Tb is very similar to (177)Lu with respect to half-life, beta energy and chemical properties. However, (161)Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to (177)Lu. It also emits low-energy photons that are useful for gamma camera imaging. The (160)Gd(n,γ)(161)Gd→(161)Tb production route was used to produce (161)Tb by neutron irradiation of massive (160)Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) (161)Tb from the bulk of the (160)Gd target and from its stable decay product (161)Dy. (161)Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. (177)Lu. A (161)Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Up to 15 GBq of (161)Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available (161)Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The (161)Tb obtained was of the quality required to prepare (161)Tb-DOTA-Tyr3-octreotate. We were able to produce (161)Tb in n.c.a. form by irradiating highly enriched (160)Gd targets; it can be obtained in the quantity and quality required for the preparation of (161)Tb-labeled therapeutic agents. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Low Energy Scanned Electron-Beam Dose Distribution in Thin Layers

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Hjortenberg, P. E.; Pedersen, Walther Batsberg

    1975-01-01

    Thin radiochromic dye film dosimeters, calibrated by means of calorimetry, make possible the determination of absorbed-dose distributions due to low-energy scanned electron beam penetrations in moderately thin coatings and laminar media. For electrons of a few hundred keV, calibrated dosimeters...... of about 30–60 μm thickness may be used in stacks or interleaved between layers of materials of interest and supply a sufficient number of experimental data points throughout the depth of penetration of electrons to provide a depth-dose curve. Depth doses may be resolved in various polymer layers...... on different backings (wood, aluminum, and iron) for scanned electron beams (Emax = 400 keV) having a broad energy spectrum and diffuse incidence, such as those used in radiation curing of coatings, textiles, plastics, etc. Theoretical calculations of such distributions of energy depositions are relatively...

  10. Positron annihilation induced Auger electron spectroscopy and its implementation at accelerator based low energy positron factories

    International Nuclear Information System (INIS)

    Weiss, A.; Koeymen, A.R.; Mehl, D.; Lee, K.H.; Yang Gimo; Jensen, K.

    1991-01-01

    Positron annihilation induced auger electron spectroscopy (PAES) makes use of a beam of low energy positrons to excite Auger transitions by annihilating core electrons. The large secondary electron background usually present in Auger spectra can be eliminated by setting the positron beam energy well below the Auger electron energy. This allows true Auger lineshapes to be obtained. Further, because the positron is localized just outside the surface before it annihilates, PAES is extremely sensitive to the topmost atomic layer. Recent PAES results obtained at the University of Texas at Arlington will be presented. In addition, the use of high resolution energy analyzers with multichannel particle detection schemes to prevent problems due to the high data rates associated with accelerator based positron beams will be discussed. (orig.)

  11. The mass effect model of the survival rate's dose effect of organism irradiated with low energy ion beam

    International Nuclear Information System (INIS)

    Shao Chunlin; Gui Qifu; Yu Zengliang

    1995-01-01

    The main characteristic of the low energy ions mutation is its mass deposition effect. Basing on the theory of 'double strand breaking' and the 'mass deposition effect', the authors suggests that the mass deposition products can repair or further damage the double strand breaking of DNA. According to this consideration the dose effect model of the survival rate of organism irradiated by low energy of N + ion beam is deduced as: S exp{-p[αφ + βφ 2 -Rφ 2 exp(-kφ)-Lφ 3 exp(-kφ)]}, which can be called 'mass effect model'. In the low energy ion beam mutation, the dose effects of many survival rates that can not be imitated by previous models are successfully imitated by this model. The suitable application fields of the model are also discussed

  12. Sewage sludge irradiation with electrons

    International Nuclear Information System (INIS)

    Tauber, M.

    1976-01-01

    The disinfection of sewage sludge by irradiation has been discussed very intensively in the last few months. Powerful electron accelerators are now available and the main features of the irradiation of sewage sludge with fast electrons are discussed and the design parameters of such installations described. AEG-Telefunken is building an irradiation plant with a 1.5 MeV, 25 mA electron accelerator, to study the main features of electron irradiation of sewage sludge. (author)

  13. eV-TEM: Transmission electron microscopy in a low energy cathode lens instrument

    Energy Technology Data Exchange (ETDEWEB)

    Geelen, Daniël, E-mail: geelen@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Thete, Aniket [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Schaff, Oliver; Kaiser, Alexander [SPECS GmbH, Voltastrasse 5, D-13355 Berlin (Germany); Molen, Sense Jan van der [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Tromp, Rudolf [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States)

    2015-12-15

    We are developing a transmission electron microscope that operates at extremely low electron energies, 0–40 eV. We call this technique eV-TEM. Its feasibility is based on the fact that at very low electron energies the number of energy loss pathways decreases. Hence, the electron inelastic mean free path increases dramatically. eV-TEM will enable us to study elastic and inelastic interactions of electrons with thin samples. With the recent development of aberration correction in cathode lens instruments, a spatial resolution of a few nm appears within range, even for these very low electron energies. Such resolution will be highly relevant to study biological samples such as proteins and cell membranes. The low electron energies minimize adverse effects due to radiation damage. - Highlights: • We present a new way of performing low energy transmission electron microscopy in an aberration corrected LEEM/PEEM instrument. • We show a proof of principle where we measure transmitted electrons through a suspended graphene monolayer with a preliminary setup. • We present an improved setup design that provides better control of the incident electron beam.

  14. Low energy electron attachment to SF6 in N2, Ar, and Xe buffer gases

    International Nuclear Information System (INIS)

    Hunter, S.R.; Carter, J.G.; Christophorou, L.G.

    1989-01-01

    The electron attachment rate constants k/sub a/ for SF 6 have been measured in dilute mixtures of SF 6 in high pressure (>1 atm) N 2 , Ar, and Xe buffer gases at room temperature (T≅300 K) over a wide E/N range (electric field strength to gas number density ratio), corresponding to mean electron energies from near thermal electron energies (≅0.04 eV) to ≅4.3 eV. Particular attention has been paid to the effects of space charge distortion, molecular impurities, and changes in the electron energy distribution function on the measured electron attachment rate constant values at the lower E/N values in these mixtures. The present measured thermal electron attachment rate constants in SF 6 /N 2 and SF 6 /Xe gas mixtures are in excellent agreement with recent accurate measurements of these parameters in several SF 6 /buffer gas mixtures. At higher values, the present SF 6 /N 2 measurements are in fair agreement with previous measurements, while no previous measurements using Ar and Xe buffer gases have been published. These measurements have been used in numerical two term, spherical harmonic Boltzmann equation analyses of the electron motion in these gas mixtures to obtain the low energy ( 6 . The present derived electron attachment cross sections are compared with recently measured and derived nondissociative and dissociative electron attachment cross sections for SF 6

  15. Radiobiological application of simulation of low-energy electron transport in liquid water

    International Nuclear Information System (INIS)

    Eudaldo Puell, Teresa.

    1979-01-01

    A Monte-Carlo transport simulation method, so-called event-after-event method provide results about trajectories of low-energy electrons, slowing-down in liquid water. A radiosensitive target model constituted by water cylindrical volumes, like the ones which surround the DNA molecule, is taken into consideration. The results characterizing the primary physical stage of radiation action, such as, space ionization distributions, interionization distance distributions ..., are obtained in some configurations constituted by single or several targets, in order to approach the biological reality [fr

  16. Effect of tissue inhomogeneity on dose distribution of point sources of low-energy electrons

    International Nuclear Information System (INIS)

    Kwok, C.S.; Bialobzyski, P.J.; Yu, S.K.; Prestwich, W.V.

    1990-01-01

    Perturbation in dose distributions of point sources of low-energy electrons at planar interfaces of cortical bone (CB) and red marrow (RM) was investigated experimentally and by Monte Carlo codes EGS and the TIGER series. Ultrathin LiF thermoluminescent dosimeters were used to measure the dose distributions of point sources of 204 Tl and 147 Pm in RM. When the point sources were at 12 mg/cm 2 from a planar interface of CB and RM equivalent plastics, dose enhancement ratios in RM averaged over the region 0--12 mg/cm 2 from the interface were measured to be 1.08±0.03 (SE) and 1.03±0.03 (SE) for 204 Tl and 147 Pm, respectively. The Monte Carlo codes predicted 1.05±0.02 and 1.01±0.02 for the two nuclides, respectively. However, EGS gave consistently 3% higher dose in the dose scoring region than the TIGER series when point sources of monoenergetic electrons up to 0.75 MeV energy were considered in the homogeneous RM situation or in the CB and RM heterogeneous situation. By means of the TIGER series, it was demonstrated that aluminum, which is normally assumed to be equivalent to CB in radiation dosimetry, leads to an overestimation of backscattering of low-energy electrons in soft tissue at a CB--soft-tissue interface by as much as a factor of 2

  17. Calculation of W for low energy electrons in tissue-equivalent gas. [<10 keV

    Energy Technology Data Exchange (ETDEWEB)

    Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

    1977-11-01

    The mean energy expended per ion pair formed (W-value) in the tissue-equivalent gas for incident electrons of energy up to 10 keV has been calculated in the continuous slowing-down approximation. The effect of secondary and tertiary electrons has been considered by utilizing recent measurements of Opal et al., (1971, J. Chem. Phys., 55,4100) on the energy spectra of low-energy secondary electrons and the Mott formula for the spectra of high-energy secondaries. The results, which are provisional in nature due to the limitations on the accuracy of the input cross-section data and the neglect of the discrete nature of energy loss process, are compared with the available measurements.

  18. Effects of irradiation with low-energy nitrogen ion injection on root tip cells of broad bean

    International Nuclear Information System (INIS)

    Huang Yaqin; Li Jinzhe; Huang Qunce

    2012-01-01

    In order to study the cytogenetic effects of low-energy nitrogen ion irradiation, broad bean seed embryo was irradiated by different doses of nitrogen ions. Micronucleus rate, mitotic index and chromosome aberration in root-tip cells were analyzed. The results showed that the injection of ions inhibited mitosis of root tip cells, interfered the normal process of mitosis, caused aberrations of chromosome structure, behavior and number. The frequency of micronucleus and chromosomal aberrations increased with the increasing radiation dosage, while mitotic index decreased. (authors)

  19. Tailoring molybdenum nanostructure evolution by low-energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Hassanein, A.

    2015-10-30

    Mirror-finished polished molybdenum (Mo) samples were irradiated with 100 eV He{sup +} ions as a function of ion fluence (using a constant flux of 7.2 × 10{sup 20} ions m{sup −2} s{sup −1}) at normal incidence and at 923 K. Mo surface deterioration and nanoscopic fiber-form filament (“Mo fuzz”) growth evolution were monitored by using field emission (FE) scanning electron (SEM) and atomic force (AFM) microscopy studies. Those studies confirm a reasonably clean and flat surface, up to several micrometer scales along with a few mechanical-polishing-induced scratches. However, He{sup +} ion irradiation deteriorates the surface significantly even at 2.1 × 10{sup 23} ions m{sup −2} fluence (about 5 min. irradiation time) and leads to evolution of homogeneously populated ∼75-nm-long Mo nanograins having ∼8 nm intergrain width. The primary stages of Mo fuzz growth, i.e., elongated half-cylindrical ∼70 nm nanoplatelets, and encapsulated bubbles of 20–45 nm in diameter and preferably within the grain boundaries of sub-micron-sized grains, were observed after 1.3 × 10{sup 24} ions m{sup −2} fluence irradiation. Additionally, a sequential enhancement in the sharpness, density, and protrusions of Mo fuzz at the surface with ion fluence was also observed. Fluence- and flux-dependent studies have also been performed at 1223 K target temperature (beyond the temperature window for Mo fuzz formation). At a constant fluence of 2.6 × 10{sup 24} ions m{sup −2}, 7.2 × 10{sup 20} ions m{sup −2} s{sup −1} flux generates a homogeneous layered and stacked nanodiscs of ∼70 nm diameter. On the other hand, 1.2 × 10{sup 21} ions m{sup −2} s{sup −1} flux generates a combination of randomly patched netlike nanomatrix networked structure, mostly with ∼105 nm nanostructure wall width, various-shaped pores, and self-organized nano arrays. While the observed netlike nanomatrix network structures for 8.6 × 10{sup 24} ions m{sup −2} fluence (at a constant

  20. Tailoring molybdenum nanostructure evolution by low-energy He+ ion irradiation

    International Nuclear Information System (INIS)

    Tripathi, J.K.; Novakowski, T.J.; Hassanein, A.

    2015-01-01

    Mirror-finished polished molybdenum (Mo) samples were irradiated with 100 eV He + ions as a function of ion fluence (using a constant flux of 7.2 × 10 20 ions m −2 s −1 ) at normal incidence and at 923 K. Mo surface deterioration and nanoscopic fiber-form filament (“Mo fuzz”) growth evolution were monitored by using field emission (FE) scanning electron (SEM) and atomic force (AFM) microscopy studies. Those studies confirm a reasonably clean and flat surface, up to several micrometer scales along with a few mechanical-polishing-induced scratches. However, He + ion irradiation deteriorates the surface significantly even at 2.1 × 10 23 ions m −2 fluence (about 5 min. irradiation time) and leads to evolution of homogeneously populated ∼75-nm-long Mo nanograins having ∼8 nm intergrain width. The primary stages of Mo fuzz growth, i.e., elongated half-cylindrical ∼70 nm nanoplatelets, and encapsulated bubbles of 20–45 nm in diameter and preferably within the grain boundaries of sub-micron-sized grains, were observed after 1.3 × 10 24 ions m −2 fluence irradiation. Additionally, a sequential enhancement in the sharpness, density, and protrusions of Mo fuzz at the surface with ion fluence was also observed. Fluence- and flux-dependent studies have also been performed at 1223 K target temperature (beyond the temperature window for Mo fuzz formation). At a constant fluence of 2.6 × 10 24 ions m −2 , 7.2 × 10 20 ions m −2 s −1 flux generates a homogeneous layered and stacked nanodiscs of ∼70 nm diameter. On the other hand, 1.2 × 10 21 ions m −2 s −1 flux generates a combination of randomly patched netlike nanomatrix networked structure, mostly with ∼105 nm nanostructure wall width, various-shaped pores, and self-organized nano arrays. While the observed netlike nanomatrix network structures for 8.6 × 10 24 ions m −2 fluence (at a constant flux of 1.2 × 10 21 ions m −2 s −1 ) is quite similar to those for 2.6 × 10 24 ions m −2

  1. Tailoring molybdenum nanostructure evolution by low-energy He+ ion irradiation

    Science.gov (United States)

    Tripathi, J. K.; Novakowski, T. J.; Hassanein, A.

    2015-10-01

    Mirror-finished polished molybdenum (Mo) samples were irradiated with 100 eV He+ ions as a function of ion fluence (using a constant flux of 7.2 × 1020 ions m-2 s-1) at normal incidence and at 923 K. Mo surface deterioration and nanoscopic fiber-form filament ("Mo fuzz") growth evolution were monitored by using field emission (FE) scanning electron (SEM) and atomic force (AFM) microscopy studies. Those studies confirm a reasonably clean and flat surface, up to several micrometer scales along with a few mechanical-polishing-induced scratches. However, He+ ion irradiation deteriorates the surface significantly even at 2.1 × 1023 ions m-2 fluence (about 5 min. irradiation time) and leads to evolution of homogeneously populated ∼75-nm-long Mo nanograins having ∼8 nm intergrain width. The primary stages of Mo fuzz growth, i.e., elongated half-cylindrical ∼70 nm nanoplatelets, and encapsulated bubbles of 20-45 nm in diameter and preferably within the grain boundaries of sub-micron-sized grains, were observed after 1.3 × 1024 ions m-2 fluence irradiation. Additionally, a sequential enhancement in the sharpness, density, and protrusions of Mo fuzz at the surface with ion fluence was also observed. Fluence- and flux-dependent studies have also been performed at 1223 K target temperature (beyond the temperature window for Mo fuzz formation). At a constant fluence of 2.6 × 1024 ions m-2, 7.2 × 1020 ions m-2 s-1 flux generates a homogeneous layered and stacked nanodiscs of ∼70 nm diameter. On the other hand, 1.2 × 1021 ions m-2 s-1 flux generates a combination of randomly patched netlike nanomatrix networked structure, mostly with ∼105 nm nanostructure wall width, various-shaped pores, and self-organized nano arrays. While the observed netlike nanomatrix network structures for 8.6 × 1024 ions m-2 fluence (at a constant flux of 1.2 × 1021 ions m-2 s-1) is quite similar to those for 2.6 × 1024 ions m-2 fluence, the nanostructure wall width extends up to ∼45

  2. Low-energy electron emitters for targeted radiotherapy of small tumours

    International Nuclear Information System (INIS)

    Bernhardt, Peter; Forssell-Aronsson, Eva; Jacobsson, Lars; Skarnemark, Gunnar

    2001-01-01

    The possibility of using electron emitters to cure a cancer with metastatic spread depends on the energy of the emitted electrons. Electrons with high energy will give a high, absorbed dose to large tumours, but the absorbed dose to small tumours or single tumour cells will be low, because the range of the electrons is too long. The fraction of energy absorbed within the tumour decreases with increasing electron energy and decreasing tumour size. For tumours smaller than 1 g, the tumour-to-normal-tissue mean absorbed dose-rate ratio, TND, will be low, e.g. for 131 I and 90 Y, because of the high energy of the emitted electrons. For radiotherapy of small tumours, radionuclides emitting charged particles with short ranges (a few m u m ) are required. A mathematical model was constructed to evaluate the relation between TND and electron energy, photon-to-electron energy ratio, p/e, and tumour size. Criteria for the selection of suitable radionuclides for the treatment of small tumours were defined based on the results of the TND model. In addition, the possibility of producing such radionuclides and their physical and chemical properties were evaluated. Based on the mathematical model, the energy of the emitted electrons should be = 40 keV for small tumours ( 58m Co, 103m Rh, 119 Sb, 161 Ho, and 189m Os. All of these nuclides by internal transition or electron capture, which yields conversion and Auger electrons, and it should be possible to produce most of them in therapeutic amounts. The five low-energy electron-emitting radionuclides identified may be relevant in the radiation treatment of small tumours, especially if bound to internalizing radiopharmaceuticals

  3. Low-Energy Electron Scattering Data for Chemical Plasma Treatment of Biomass

    International Nuclear Information System (INIS)

    Lima, Marco A.P.

    2014-01-01

    Full text: Replacing fossil fuels with biofuels from renewable sources is an important goal for reducing greenhouse gas emissions. Many countries are already using few percent of ethanol in the gasoline and few of them, with more aggressive programs, have developed flex fuel engines that can run with any mixture of gasoline and ethanol. An important point is how to produce ethanol in a sustainable way and with which technology? Biomass is a good candidate since it has cellulose and hemicellulose as source of sugars. In order to liberate these sugars for fermentation, it is important to learn how to separate the main components. Chemical routes (acid treatment) and biological routes (enzymatic hydrolysis) are combined and used for these purposes. Atmospheric plasmas can be useful for attacking the biomass in a controlled manner and low-energy electrons may have an important role in the process. Recently we have been studying the interaction of electrons with lignin subunits (phenol, guaiacol, p-coumaryl alcohol), cellulose components, β-D-glucose and cellobiose (β(1 - 4) linked glucose dimer) and hemicellulose components (β-D-xylose). We also obtained results for the amylose subunits α-D-glucose and maltose (α(1 - 4) linked glucose dimer). Altogether, the resonance spectra of lignin, cellulose and hemicellulose components establish a physical–chemical basis for electron-induced biomass pretreatment that could be applied to biofuel production. In my talk I will give a progress report on this matter. We will also discuss microsolvation effects on the electron-phenol scattering process and present our strategy to study molecular dissociation through electronic excitation of low energy triplet states. (author)

  4. Low-energy electron diffraction and induced damage in hydrated DNA

    International Nuclear Information System (INIS)

    Orlando, Thomas M.; Oh, Doogie; Chen Yanfeng; Aleksandrov, Alexandr B.

    2008-01-01

    Elastic scattering of 5-30 eV electrons within the B-DNA 5 ' -CCGGCGCCGG-3 ' and A-DNA 5 ' -CGCGAATTCGCG-3 ' DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30 eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18, and 22-28 eV for the B-DNA target and at 7-11, 12-18, and 18-25 eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 A spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H 2 O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks

  5. Point defects induced in LiF by low energy electrons

    International Nuclear Information System (INIS)

    Baldacchini, Giuseppe; Montereali, Rosa Maria; Scacco, Augusto; Cremona, Marco; D'Auria, Giuliano.

    1997-09-01

    A systematic study of the coloring of LiF crystals and films irradiated by 3 keV electrons at various temperatures was carried out analysing their absorption and luminescence spectra. The three stage behaviour of the F coloring curve as a function of the irradiation dose was revealed and the saturation of the process was identified for the first time with this kind of radiation. The kinetics of the defect formation confirmed the expectations derived from the most comprehensive theoretical model developed to explain the coloring process. The irradiation temperature was found to have an influence on both the proportion of different defects created and on their stability and the overall coloring efficiency turned out to be higher when the irradiation was performed on films. Various explanations to these observations are put forward and discussed

  6. Point defects induced in LiF by low energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Baldacchini, Giuseppe; Montereali, Rosa Maria [ENEA, Centro Ricerche Frascati, Rome (Italy); Scacco, Augusto [Rome, Univ. (Italy). Dipt. di Fisica]|[INFM, Rome (Italy); Cremona, Marco; D`Auria, Giuliano

    1997-09-01

    A systematic study of the coloring of LiF crystals and films irradiated by 3 keV electrons at various temperatures was carried out analysing their absorption and luminescence spectra. The three stage behaviour of the F coloring curve as a function of the irradiation dose was revealed and the saturation of the process was identified for the first time with this kind of radiation. The kinetics of the defect formation confirmed the expectations derived from the most comprehensive theoretical model developed to explain the coloring process. The irradiation temperature was found to have an influence on both the proportion of different defects created and on their stability and the overall coloring efficiency turned out to be higher when the irradiation was performed on films. Various explanations to these observations are put forward and discussed.

  7. Radiation induced low-energy electron transport in a tissue environment

    International Nuclear Information System (INIS)

    Toburen, L.H.; Dingfelder, M.; Ozturk, N.; Christou, C.; Shinpaugh, J.L.; Friedland, W.; Wilson, W.E.; Paretzke, H.G.

    2003-01-01

    Monte Carlo (MC) track simulation codes are used extensively in radiobiology to quantify the spatial distributions of interactions initiated by the absorption of ionizing radiation. The spatial patterns of ionization and excitation are instrumental for assessing the formation of damage clusters in DNA and chromosomes leading to such biologic endpoints as cellular transformation and mutation. The MC codes rely on an extensive database of elastic and inelastic scattering cross sections to follow the production and slowing of secondary electrons. Because of inherent uncertainties in this database we are exploring the sensitivity of MC results to the details of the cross sections used with emphasis on low-energy electrons, i.e., track ends, that are anticipated to play a dominant role in damage cluster formation. Simulations of electron transport using gas or liquid based interaction cross sections illustrate substantial difference in the spectra of electrons with energies less than about 50 eV. In addition, the electron yields from MC simulations appear to be nearly a factor of five larger than our recent measurements of electron transport spectra in water (ice) at electron energies of about 10 eV. Examples of the changes in electron transport spectra for variations in the electron scattering cross sections used for the MC calculations will be illustrated and compared with an evolving database of measured spectra of electrons from ion induced secondary electron transport in thin foils. These measurements provide guidance for assessment of elastic and elastic cross sections appropriate to condensed phase transport. This work is supported in part by the U.S. Department of Energy, Grant No. DE-FG02-01ER-63233; the National Cancer Institute, Grant No. 1R01CA93351-01A1; and the European Community under Contract No. FIGH-CT-1999-00005

  8. Temperature dependent surface modification of molybdenum due to low energy He+ ion irradiation

    International Nuclear Information System (INIS)

    Tripathi, J.K.; Novakowski, T.J.; Joseph, G.; Linke, J.; Hassanein, A.

    2015-01-01

    In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He + ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 10 24 ions m −2 (with a flux of 7.2 × 10 20 ions m −2 s −1 ). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823–1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO 3 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth

  9. Electronic structure of xenon implanted with low energy in amorphous silicon

    International Nuclear Information System (INIS)

    Barbieri, P.F.; Landers, R.; Oliveira, M.H. de; Alvarez, F.; Marques, F.C.

    2007-01-01

    Electronic structure of Xe implanted in amorphous silicon (a-Si) films are investigated. Xe atoms were implanted with low energy by ion beam assisted deposition (IBAD) technique during growth of the a-Si films. The Xe implantation energy varied in the 0-300 eV energy range. X-ray photoelectron spectroscopy (XPS), X-ray Auger excited spectroscopy (XAES) and X-ray absorption spectroscopy (XAS) were used for investigating the Xe electronic structure. The Xe M 4 N 45 N 45 transitions were measured to extract the Auger parameter and to analyze the initial state and relaxation contributions. It was found that the binding energy variation is mainly due to initial state contribution. The relaxation energy variation also shows that the Xe trapped environment depends on the implantation energy. XAS measurements reveals that Xe atoms are dispersed in the a-Si matrix

  10. Modelling low energy electron and positron tracks in biologically relevant media

    International Nuclear Information System (INIS)

    Blanco, F.; Munoz, A.; Almeida, D.; Ferreira da Silva, F.; Limao-Vieira, P.; Fuss, M.C.; Sanz, A.G.; Garcia, G.

    2013-01-01

    This colloquium describes an approach to incorporate into radiation damage models the effect of low and intermediate energy (0-100 eV) electrons and positrons, slowing down in biologically relevant materials (water and representative biomolecules). The core of the modelling procedure is a C++ computing programme named 'Low Energy Particle Track Simulation (LEPTS)', which is compatible with available general purpose Monte Carlo packages. Input parameters are carefully selected from theoretical and experimental cross section data and energy loss distribution functions. Data sources used for this purpose are reviewed showing examples of electron and positron cross section and energy loss data for interactions with different media of increasing complexity: atoms, molecules, clusters and condense matter. Finally, we show how such a model can be used to develop an effective dosimetric tool at the molecular level (i.e. nanodosimetry). Recent experimental developments to study the fragmentation induced in biologically material by charge transfer from neutrals and negative ions are also included. (authors)

  11. Reciprocal space mapping by spot profile analyzing low energy electron diffraction

    International Nuclear Information System (INIS)

    Meyer zu Heringdorf, Frank-J.; Horn-von Hoegen, Michael

    2005-01-01

    We present an experimental approach for the recording of two-dimensional reciprocal space maps using spot profile analyzing low energy electron diffraction (SPA-LEED). A specialized alignment procedure eliminates the shifting of LEED patterns on the screen which is commonly observed upon variation of the electron energy. After the alignment, a set of one-dimensional sections through the diffraction pattern is recorded at different energies. A freely available software tool is used to assemble the sections into a reciprocal space map. The necessary modifications of the Burr-Brown computer interface of the two Leybold and Omicron type SPA-LEED instruments are discussed and step-by-step instructions are given to adapt the SPA 4.1d software to the changed hardware. Au induced faceting of 4 deg. vicinal Si(001) is used as an example to demonstrate the technique

  12. Low-Energy Electron-Induced Strand Breaks in Telomere-Derived DNA Sequences-Influence of DNA Sequence and Topology.

    Science.gov (United States)

    Rackwitz, Jenny; Bald, Ilko

    2018-03-26

    During cancer radiation therapy high-energy radiation is used to reduce tumour tissue. The irradiation produces a shower of secondary low-energy (DNA very efficiently by dissociative electron attachment. Recently, it was suggested that low-energy electron-induced DNA strand breaks strongly depend on the specific DNA sequence with a high sensitivity of G-rich sequences. Here, we use DNA origami platforms to expose G-rich telomere sequences to low-energy (8.8 eV) electrons to determine absolute cross sections for strand breakage and to study the influence of sequence modifications and topology of telomeric DNA on the strand breakage. We find that the telomeric DNA 5'-(TTA GGG) 2 is more sensitive to low-energy electrons than an intermixed sequence 5'-(TGT GTG A) 2 confirming the unique electronic properties resulting from G-stacking. With increasing length of the oligonucleotide (i.e., going from 5'-(GGG ATT) 2 to 5'-(GGG ATT) 4 ), both the variety of topology and the electron-induced strand break cross sections increase. Addition of K + ions decreases the strand break cross section for all sequences that are able to fold G-quadruplexes or G-intermediates, whereas the strand break cross section for the intermixed sequence remains unchanged. These results indicate that telomeric DNA is rather sensitive towards low-energy electron-induced strand breakage suggesting significant telomere shortening that can also occur during cancer radiation therapy. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Improved age-diffusion model for low-energy electron transport in solids. I. Theory

    International Nuclear Information System (INIS)

    Devooght, J.; Dubus, A.; Dehaes, J.C.

    1987-01-01

    We have developed in this paper a semianalytical electron transport model designed for parametric studies of secondary-electron emission induced by low-energy electrons (keV range) and by fast light ions (100 keV range). The primary-particle transport is assumed to be known and to give rise to an internal electron source. The importance of the nearly isotropic elastic scattering in the secondary-electron energy range (50 eV) and the slowing-down process strongly reduce the influence of the anisotropy of the internal electron source, and the internal electron flux is nearly isotropic as is evidenced by the experimental results. The differential energy behavior of the inelastic scattering kernel is very complicated and the real kernel is replaced by a synthetic scattering kernel of which parameters are obtained by energy and angle moments conservation. Through a P 1 approximation and the use of the synthetic scattering kernel, the Boltzmann equation is approximated by a diffusion--slowing-down equation for the isotropic part of the internal electron flux. The energy-dependent partial reflection boundary condition reduces to a Neumann-Dirichlet boundary condition. An analytical expression for the Green's function of the diffusion--slowing-down equation with the surface boundary condition is obtained by means of approximations close to the age-diffusion theory and the model allows for transient conditions. Independently from the ''improved age-diffusion'' model, a correction formula is developed in order to take into account the backscattering of primary electrons for an incident-electron problem

  14. Low-energy positron and electron diffraction and positron-stimulated secondary electron emission from Cu(100)

    International Nuclear Information System (INIS)

    Weiss, A.H.

    1983-01-01

    The results of two series of experiments are reported. In the first, an electrostatically guided beam of low-energy (40-400 eV) positrons, delta/sub p/ was used to study low-energy positron diffraction (LEPD) from a Cu(100) surface under ultrahigh-vacuum conditions. Low-energy electron diffraction (LEED) data were obtained from the same sample in the same apparatus. Comparison of LEPD and LEED intensity versus energy data with model calculations made using computer programs developed by C.B. Duke and collaborators indicated that: LEPD data is adequately modeled using potentials with no exchange-correlation term. The inelastic mean free path, lambda/sub ee/, is shorter for positrons than for electrons at low (< approx.80 eV). LEED is better than LEPD at making a determination of the first-layer spacing of Cu(100) for the particular data set reported. In the second set of experiments, the same apparatus and sample were used to compare positron- and electron-stimulated secondary-electron emission (PSSEE and ESSEE). The results were found to be consistent with existing models of secondary-electron production for metals. The energy distributions of secondary-electrons had broad low-energy (<10 eV) peaks for both positron and electron stimulation. But the PSEE distribution showed no elastic peak. Measurements of secondary-electron angular distributions, found to be cosine-like in both the PSSEE and ESSEE case, were used to obtain total secondary yield ratios, delta, at four beam energies ranging from 40-400 eV. The secondary yield ratio for primary positrons and the yield for primary electrons, delta/sub e/, were similar at these energies. For 400-eV primary particles the secondary yields were found to be delta/sub p/ = 0.94 +/- 0.12 and delta/sub e/ = 0.94 +/- 0./12, giving a ratio of unity for positron-stimulated secondary yield to electron-stimulated secondary yield

  15. Low-Energy Electrons Emitted in Ion Collisions with Thin Foils

    Science.gov (United States)

    Kraemer, Michael; Kozhuharov, Christophor; Durante, Marco; Hagmann, Siegbert; Kraft, Gerhard; Lineva, Natallia

    The realistic description of radiation damage after charged particle passage is an ongoing issue for both radiotherapy as well as space applications. In both areas of applied radiological science, living as well as nonliving matter is exposed to ionizing radiation, and it is of vital interest to predict the responses of structures like cells, detectors or electronic devices. In ion beam radiotherapy, for example, the Local Effect Model (LEM) is being used to calculate radiobiological effects with so far unprecedented versatility. This has been shown in the GSI radiotherapy pilot project and consequently this model has become the "industry standard" for treatment planning in subsequent commercial ion radiotherapy sites. The model has also been extended to nonliving matter, i.e. to describe the response of solid state detectors such as TLDs and films. A prerequisite for this model (and possibly similar ones) is the proper description of microscopic track structure and energy deposition. In particular, the area at a very low distance (¡20 nm) from the ion path needs special attention due to the locally very high dose and the rather limited experimental evidence for the shape of the dose distribution. The dose distribution at low distances is inevitably associated with the creation and transport of low-energy (sub-keV) electrons. While some data, elementary cross sections as well as dose distributions, exist for gaseous media, i.e. under single collision conditions, experimental data for the condensed phase are scarce. We have, therefore, launched a project aimed at systematic research of the energy and angular distributions of low-energy (sub-keV) electrons emitted from solids. These investigations com-prise creation as well as transport of low-energy electrons under multiple collision conditions and hence require accounting for the properties of the target, both bulk and surface, i.e. for the inherent inhomogeneity of the thickness and for the surface roughness. To

  16. An electron cyclotron resonance ion source based low energy ion beam platform

    International Nuclear Information System (INIS)

    Sun, L. T.; Shang, Y.; Ma, B. H.; Zhang, X. Z.; Feng, Y. C.; Li, X. X.; Wang, H.; Guo, X. H.; Song, M. T.; Zhao, H. Y.; Zhang, Z. M.; Zhao, H. W.; Xie, D. Z.

    2008-01-01

    To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed

  17. An electron cyclotron resonance ion source based low energy ion beam platform.

    Science.gov (United States)

    Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z

    2008-02-01

    To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.

  18. UV photon and low-energy (5--150 eV) electron-stimulated processes at environmental interfaces

    International Nuclear Information System (INIS)

    Orlando, T.M.

    1997-01-01

    Irradiation of surfaces and interfaces with low-energy (5--150 eV) electrons and ultraviolet photons occurs during the storage of ''mixed'' (chemical/radioactive) waste forms and during processing steps which involve the use of low temperature plasmas. It is well known that electron- and photon-stimulated desorption (ESD and PSD) from wide band-gap materials and interfaces can be initiated by Auger decay of deep valence and shallow core holes. This process consists of hole production, Auger decay, reversal of the Madelung potential, and ion expulsion due to the Coulomb repulsion. ESD and PSD of neutrals also occurs and involves production of electron-hole pairs and excitons. Generally, neutral yields dominate ESD and PSD cross sections, which typically vary between ∼10 -16 and 10 -22 cm 2 . The authors present results on the ESD and PSD of environmentally relevant substrates such as ZrO 2 (100), soda-glass, and NaNO 3 . The major cation thresholds and yields indicate that ESD and PSD from these complex materials involves Auger stimulated events. In particular, desorption thresholds correlate with ionization of the O(2s), Zr(4p), Si(2p) and Na(2s) levels. The near band-gap threshold energy (∼5--7 eV) for the desorption of neutrals (i.e., atomic oxygen, NO, etc) demonstrate the overall importance of self-trapped and localized excitons in both ESD and PSD of typical ceramics and oxides

  19. Treatment of foods with 'soft-electrons' (low-energy electrons)

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Toru [Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki (Japan); Todoriki, Setsuko [National Food Research Institute (NFRI), Tsukuba, Ibaraki (Japan)

    2003-02-01

    Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

  20. Treatment of foods with 'soft-electrons' (low-energy electrons)

    International Nuclear Information System (INIS)

    Hayashi, Toru; Todoriki, Setsuko

    2003-01-01

    Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

  1. A design for a subminiature, low energy scanning electron microscope with atomic resolution

    International Nuclear Information System (INIS)

    Eastham, D. A.; Edmondson, P.; Greene, S.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

    2009-01-01

    We describe a type of scanning electron microscope that works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field, and focused to a spot using a microscale Einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 μm, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size, and an atomic emission site will give a resolution of 0.1-0.2 nm (1-2 A). Also, because the beam is not allowed to expand beyond 100 nm in diameter, the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 A) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids), it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field emission and can be up to 1x10 6 times larger than in a typical (high energy) electron microscope. The advantages of this low energy, bright-beam electron microscope with atomic resolution are described and include the possibility of it being used to rapidly sequence the human genome from a single strand of DNA as well as being able to identify atomic species directly from the elastic scattering of electrons

  2. Current status of low energy EB machine

    International Nuclear Information System (INIS)

    Toshiro Nishikimi; Shuichi Taniguchi; Kenichi Mizusawa

    1999-01-01

    Electron beam processing systems have been in use in a variety of applications such as curing of paints and printing inks, crosslinking of PE products, treating of rubber tire and so on. Low energy electron processing systems have become popular as self-shielded machines, which are compact and easy to use and do not require special facility as an irradiation room. This manuscript introduces the status of low energy EB (electron beam) machine through Nissin's products current

  3. Laboratory Measurements of Charging of Apollo 17 Lunar Dust Grains by Low Energy Electrons

    Science.gov (United States)

    Abbas, Mian M.; Tankosic, Dragana; Spann, James F.; Dube, Michael J.; Gaskin, Jessica

    2007-01-01

    It is well recognized that the charging properties of individual micron/sub-micron size dust grains by various processes are expected to be substantially different from the currently available measurements made on bulk materials. Solar UV radiation and the solar wind plasma charge micron size dust grains on the lunar surface with virtually no atmosphere. The electrostatically charged dust grains are believed to be levitated and transported long distances over the lunar terminator from the day to the night side. The current models do not fully explain the lunar dust phenomena and laboratory measurements are needed to experimentally determine the charging properties of lunar dust grains. An experimental facility has been developed in the Dusty Plasma Laboratory at NASA Marshall Space Flight Center MSFC for investigating the charging properties of individual micron/sub-micron size positively or negatively charged dust grains by levitating them in an electrodynamic balance in simulated space environments. In this paper, we present laboratory measurements on charging of Apollo 17 individual lunar dust grains by low energy electron beams in the 5-100 eV energy range. The measurements are made by levitating Apollo 17 dust grains of 0.2 to 10 micrometer diameters, in an electrodynamic balance and exposing them to mono-energetic electron beams. The charging rates and the equilibrium potentials produced by direct electron impact and by secondary electron emission processes are discussed.

  4. Electron cooling of PB$^{54+}$ ions in the low energy ion ring (LEIR)

    CERN Document Server

    Bosser, Jacques; Chanel, M; MacCaferri, R; Maury, S; Möhl, D; Molinari, G; Tranquille, G

    1998-01-01

    For the preparation of dense bunches of lead ions for the LHC, electron cooling will be essential for accumula tion in a storage ring at 4.2 MeV/u. Tests have been carried out on the LEAR ring (renamed LEIR for Low Energy Ion Ring) in order to determine the optimum parameters for a future state-of-the-art electron cooling device which would be able to cool linac pulses of lead ions in less than 100 ms. The experiments focused on the generation of a stable high intensity electron beam that is needed to free space in both longitudinal and transverse phase space for incoming pulses. Investigations on the ion beam lifetime in the presence of the electron beam and on the dependency of the cooling times on the optical settings of the storage ring will also be discussed. This paper concentrates on the cooling aspects with the multiturn injection, vacuum, and high intensity aspects discussed in a companion paper at this conference.

  5. Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, John; De Santis, Stefano; Sonnad, Kiran; Caspers, Fritz; Kroyer, Tom; Krasnykh, Anatoly; Pivi, Mauro

    2008-06-01

    Clouds of low energy electronsin the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energyelectron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave that is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.

  6. Introduction of spectroscopic photoemission and low energy electron microscope in SPring-8

    International Nuclear Information System (INIS)

    Guo, FangZhun; Kobayashi, Keisuke; Kinoshita, Toyohiko

    2005-01-01

    An upright configuration SPELEEM (Spectroscopic PhotoEmission and Low Energy Electron Microscope) has been introduced in SPring-8 in the framework of the nanotechnology support project of Ministry of Education, Culture, Sport, Science and Technology (MEXT), Japan. SPELEEM combines microscopy, spectroscopy and diffraction in one system, which allows a comprehensive characterization of the specimen. The combination of SPELEEM and polarized (circularly or linearly) soft X-rays in SPring-8 is expected to realize the highest performance. The characteristics of SPELEEM and typical results, for example nano-XANES (X-ray absorption near edge structure) of Fe oxide on Fe(100) surface, nano-XPS (X-ray photoemission spectroscopy) of indium (In) on Si(111) and antiferro-magnetic domain structure images of NiO(001) single crystal, are reported. (author)

  7. Low-energy electron diffraction experiment, theory and surface structure determination

    CERN Document Server

    Hove, Michel A; Chan, Chi-Ming

    1986-01-01

    Surface crystallography plays the same fundamental role in surface science which bulk crystallography has played so successfully in solid-state physics and chemistry. The atomic-scale structure is one of the most important aspects in the understanding of the behavior of surfaces in such widely diverse fields as heterogeneous catalysis, microelectronics, adhesion, lubrication, cor­ rosion, coatings, and solid-solid and solid-liquid interfaces. Low-Energy Electron Diffraction or LEED has become the prime tech­ nique used to determine atomic locations at surfaces. On one hand, LEED has yielded the most numerous and complete structural results to date (almost 200 structures), while on the other, LEED has been regarded as the "technique to beat" by a variety of other surface crystallographic methods, such as photoemission, SEXAFS, ion scattering and atomic diffraction. Although these other approaches have had impressive successes, LEED has remained the most productive technique and has shown the most versatility...

  8. Ultra Low Energy Binary Decision Diagram Circuits Using Few Electron Transistors

    Science.gov (United States)

    Saripalli, Vinay; Narayanan, Vijay; Datta, Suman

    Novel medical applications involving embedded sensors, require ultra low energy dissipation with low-to-moderate performance (10kHz-100MHz) driving the conventional MOSFETs into sub-threshold operation regime. In this paper, we present an alternate ultra-low power computing architecture using Binary Decision Diagram based logic circuits implemented using Single Electron Transistors (SETs) operating in the Coulomb blockade regime with very low supply voltages. We evaluate the energy - performance tradeoff metrics of such BDD circuits using time domain Monte Carlo simulations and compare them with the energy-optimized CMOS logic circuits. Simulation results show that the proposed approach achieves better energy-delay characteristics than CMOS realizations.

  9. Ab initio study of low-energy electrons interacting with HCN molecules

    International Nuclear Information System (INIS)

    Jain, A.; Norcross, D.W.

    1984-01-01

    Our earlier study of low-energy electron scattering with HCN molecules is further improved by treating exchange exactly (in a separable exchange approximation 2 ) in Σ, π and Δ symmetries: the 3.8 eV π resonance is shifted towards lower energy (2.56 eV, the experimental position is around 2.26 eV 3 ), while in Σ and the Δ symmetries the difference is within 15%. We also study possible negative ion states of HCN by calculating potential energy curves with respect to C-H and C-N stretches. For example, there is evidence of an avoiding crossing between a 1Σ + and a 2Σ + state (C-H stretch) of HCN -

  10. A monochromatic, aberration-corrected, dual-beam low energy electron microscope.

    Science.gov (United States)

    Mankos, Marian; Shadman, Khashayar

    2013-07-01

    The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Progress toward an aberration-corrected low energy electron microscope for DNA sequencing and surface analysis.

    Science.gov (United States)

    Mankos, Marian; Shadman, Khashayar; N'diaye, Alpha T; Schmid, Andreas K; Persson, Henrik H J; Davis, Ronald W

    2012-11-01

    Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) is a novel imaging technique aimed at high resolution imaging of macromolecules, nanoparticles, and surfaces. MAD-LEEM combines three innovative electron-optical concepts in a single tool: a monochromator, a mirror aberration corrector, and dual electron beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector is needed to achieve subnanometer resolution at landing energies of a few hundred electronvolts. The dual flood illumination approach eliminates charging effects generated when a conventional, single-beam LEEM is used to image insulating specimens. The low landing energy of electrons in the range of 0 to a few hundred electronvolts is also critical for avoiding radiation damage, as high energy electrons with kilo-electron-volt kinetic energies cause irreversible damage to many specimens, in particular biological molecules. The performance of the key electron-optical components of MAD-LEEM, the aberration corrector combined with the objective lens and a magnetic beam separator, was simulated. Initial results indicate that an electrostatic electron mirror has negative spherical and chromatic aberration coefficients that can be tuned over a large parameter range. The negative aberrations generated by the electron mirror can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies and provide a path to achieving subnanometer spatial resolution. First experimental results on characterizing DNA molecules immobilized on Au substrates in a LEEM are presented. Images obtained in a spin-polarized LEEM demonstrate that high contrast is achievable at low electron energies in the range of 1-10 eV and show that small changes in landing energy have a strong impact on the achievable contrast. The MAD-LEEM approach

  12. Projectile Coulomb center effects on low-energy electron emission from H[sup +][yields]Ne collisions

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, S. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina)); Garibotti, C. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)); Bernardi, G. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)); Focke, P. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina)); Meckbach, W. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina))

    1994-03-01

    We present doubly differential energy distributions of low-energy electrons emitted in collisions of 106 keV H[sup +] on Ne atoms. We find a relevant dependence of the measured distribution of low-energy electrons on the physical extension of the gas target and discuss a correction procedure. Our measurements enable a quantitative analysis of the shape of the soft electron peak, which is clearly evidenced by measured contour lines. Present results indicate that ''two center effects'' must be considered in order to account for the strong asymmetry of the soft electron peak observed experimentaly. (orig.)

  13. A Novel Low Energy Electron Microscope for DNA Sequencing and Surface Analysis

    Science.gov (United States)

    Mankos, M.; Shadman, K.; Persson, H.H.J.; N’Diaye, A.T.; Schmid, A.K.; Davis, R.W.

    2014-01-01

    Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) is a novel technique that is directed towards imaging nanostructures and surfaces with sub-nanometer resolution. The technique combines a monochromator, a mirror aberration corrector, an energy filter, and dual beam illumination in a single instrument. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. Simulation results predict that the novel aberration corrector design will eliminate the second rank chromatic and third and fifth order spherical aberrations, thereby improving the resolution into the sub-nanometer regime at landing energies as low as one hundred electron-Volts. The energy filter produces a beam that can extract detailed information about the chemical composition and local electronic states of non-periodic objects such as nanoparticles, interfaces, defects, and macromolecules. The dual flood illumination eliminates charging effects that are generated when a conventional LEEM is used to image insulating specimens. A potential application for MAD-LEEM is in DNA sequencing, which requires high resolution to distinguish the individual bases and high speed to reduce the cost. The MAD-LEEM approach images the DNA with low electron impact energies, which provides nucleobase contrast mechanisms without organometallic labels. Furthermore, the micron-size field of view when combined with imaging on the fly provides long read lengths, thereby reducing the demand on assembling the sequence. Experimental results from bulk specimens with immobilized single-base oligonucleotides demonstrate that base specific contrast is available with reflected, photo-emitted, and Auger electrons. Image contrast simulations of model rectangular features mimicking the individual nucleotides in a DNA strand have been developed to translate measurements of contrast on bulk DNA to the detectability of

  14. Coherent properties of a tunable low-energy electron-matter-wave source

    Science.gov (United States)

    Pooch, A.; Seidling, M.; Kerker, N.; Röpke, R.; Rembold, A.; Chang, W. T.; Hwang, I. S.; Stibor, A.

    2018-01-01

    A general challenge in various quantum experiments and applications is to develop suitable sources for coherent particles. In particular, recent progress in microscopy, interferometry, metrology, decoherence measurements, and chip-based applications rely on intensive, tunable, coherent sources for free low-energy electron-matter waves. In most cases, the electrons get field emitted from a metal nanotip, where its radius and geometry toward a counter electrode determines the field distribution and the emission voltage. A higher emission is often connected to faster electrons with smaller de Broglie wavelengths, requiring larger pattern magnification after matter-wave diffraction or interferometry. This can be prevented with a well-known setup consisting of two counter electrodes that allow independent setting of the beam intensity and velocity. However, it needs to be tested if the coherent properties of such a source are preserved after the acceleration and deceleration of the electrons. Here, we study the coherence of the beam in a biprism interferometer with a single atom tip electron field emitter if the particle velocity and wavelength varies after emission. With a Wien filter measurement and a contrast correlation analysis we demonstrate that the intensity of the source at a certain particle wavelength can be enhanced up to a factor of 6.4 without changing the transverse and longitudinal coherence of the electron beam. In addition, the energy width of the single atom tip emitter was measured to be 377 meV, corresponding to a longitudinal coherence length of 82 nm. The design has potential applications in interferometry, microscopy, and sensor technology.

  15. A novel low energy electron microscope for DNA sequencing and surface analysis.

    Science.gov (United States)

    Mankos, M; Shadman, K; Persson, H H J; N'Diaye, A T; Schmid, A K; Davis, R W

    2014-10-01

    Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) is a novel technique that is directed towards imaging nanostructures and surfaces with sub-nanometer resolution. The technique combines a monochromator, a mirror aberration corrector, an energy filter, and dual beam illumination in a single instrument. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. Simulation results predict that the novel aberration corrector design will eliminate the second rank chromatic and third and fifth order spherical aberrations, thereby improving the resolution into the sub-nanometer regime at landing energies as low as one hundred electron-Volts. The energy filter produces a beam that can extract detailed information about the chemical composition and local electronic states of non-periodic objects such as nanoparticles, interfaces, defects, and macromolecules. The dual flood illumination eliminates charging effects that are generated when a conventional LEEM is used to image insulating specimens. A potential application for MAD-LEEM is in DNA sequencing, which requires high resolution to distinguish the individual bases and high speed to reduce the cost. The MAD-LEEM approach images the DNA with low electron impact energies, which provides nucleobase contrast mechanisms without organometallic labels. Furthermore, the micron-size field of view when combined with imaging on the fly provides long read lengths, thereby reducing the demand on assembling the sequence. Experimental results from bulk specimens with immobilized single-base oligonucleotides demonstrate that base specific contrast is available with reflected, photo-emitted, and Auger electrons. Image contrast simulations of model rectangular features mimicking the individual nucleotides in a DNA strand have been developed to translate measurements of contrast on bulk DNA to the detectability of

  16. Low energy electron-initiated ion-molecule reactions of ribose analogues

    International Nuclear Information System (INIS)

    Mozejko, P.

    2003-01-01

    Recent experiments in which plasmid DNA samples were bombarded with low energy ( 2 O, DNA bases, and sugar-phosphate backbone analogues. To this end, the cyclic molecule tetrahydrofuran, and its derivatives, provide useful models for the sugar-like molecules contained in the backbone of DNA. In addition to LEE induced dissociation by processes such as dissociative electron attachment (DEA), molecules may be damaged by ions and neutral species of non-thermal energies created by LEE in the surrounding environment. In this contribution, we investigate with electron stimulated desorption techniques, LEE damage to films of desoxy-ribose analogues in the presence of various molecular coadsorbates, that simulate changes in local molecular environment. In one type of experiments tetrahydrofuran is deposited onto multilayer O2. A desorbed signal of OH - indicates ion-molecule reactions of the type O - + C 4 H 8 O -> OH - + C 4 H 7 O, where the O - was formed initially by DEA to O 2 . Further electron stimulated desorption measurements for tetrahydrofuran and derivatives adsorbed on H 2 O, Kr, N 2 O and CH 3 OH will be presented and discussed

  17. Validities of three multislice algorithms for quantitative low-energy transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ming, W.Q.; Chen, J.H., E-mail: jhchen123@hnu.edu.cn

    2013-11-15

    Three different types of multislice algorithms, namely the conventional multislice (CMS) algorithm, the propagator-corrected multislice (PCMS) algorithm and the fully-corrected multislice (FCMS) algorithm, have been evaluated in comparison with respect to the accelerating voltages in transmission electron microscopy. Detailed numerical calculations have been performed to test their validities. The results show that the three algorithms are equivalent for accelerating voltage above 100 kV. However, below 100 kV, the CMS algorithm will introduce significant errors, not only for higher-order Laue zone (HOLZ) reflections but also for zero-order Laue zone (ZOLZ) reflections. The differences between the PCMS and FCMS algorithms are negligible and mainly appear in HOLZ reflections. Nonetheless, when the accelerating voltage is further lowered to 20 kV or below, the PCMS algorithm will also yield results deviating from the FCMS results. The present study demonstrates that the propagation of the electron wave from one slice to the next slice is actually cross-correlated with the crystal potential in a complex manner, such that when the accelerating voltage is lowered to 10 kV, the accuracy of the algorithms is dependent of the scattering power of the specimen. - Highlights: • Three multislice algorithms for low-energy transmission electron microscopy are evaluated. • The propagator-corrected algorithm is a good alternative for voltages down to 20 kV. • Below 20 kV, a fully-corrected algorithm has to be employed for quantitative simulations.

  18. Material dependence of electron inelastic mean free paths at low energies

    International Nuclear Information System (INIS)

    Tanuma, S.; Powell, C.J.; Penn, D.R.

    1990-01-01

    We present and discuss electron inelastic mean free path (IMFP) data for aluminum and gold in the 50--200 eV range. These elements serve as examples of IMFP calculations that have been made for 50--2000 eV electrons in 31 materials (27 elements and 4 compounds). Substantial differences are found in the shapes of the IMFP versus energy curves for Al and Au and these can be understood in terms of the different inelastic scattering mechanisms in the two metals. The minimum IMFP value occurs at 40 eV in aluminum and at 120 eV in gold, a result which is consistent with the trends expected from free-electron IMFP calculations. This result differs, however, from that expected from the Seah and Dench attenuation length formula which shows essentially no material dependence at low energies. We have extended a general formula derived earlier to describe the calculated IMFPs over the 200--2000 eV energy range to give the IMFP dependences on material and energy from 50 to 2000 eV

  19. Low Energy Electron Cooling and Accelerator Physics for the Heidelberg CSR

    International Nuclear Information System (INIS)

    Fadil, H.; Grieser, M.; Hahn, R. von; Orlov, D.; Schwalm, D.; Wolf, A.; Zajfman, D.

    2006-01-01

    The Cryogenic Storage Ring (CSR) is currently under construction at MPI-K in Heidelberg. The CSR is an electrostatic ring with a total circumference of about 34 m, straight section length of 2.5 m and will store ions in the 20 ∼ 300 keV energy range (E/Q). The cryogenic system in the CSR is expected to cool the inner vacuum chamber down to 2 K. The CSR will be equipped with an electron cooler which has also to serve as an electron target for high resolution recombination experiments. In this paper we present the results of numerical investigations of the CSR lattice with finite element calculations of the deflection and focusing elements of the ring. We also present a layout of the CSR electron cooler which will have to operate in low energy mode to cool 20 keV protons in the CSR, as well as numerical estimations of the cooling times to be expected with this device

  20. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    International Nuclear Information System (INIS)

    Alizadeh, E.; Sanche, L.

    2014-01-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N 2 , O 2 , H 2 O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N 2 had little effect on the yields of LEE-induced single and double strand breaks, both O 2 and H 2 O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O 2 and H 2 O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitization of these agents in chemo-radiation cancer therapy. (authors)

  1. Surface modification of TA2 pure titanium by low energy high current pulsed electron beam treatments

    International Nuclear Information System (INIS)

    Gao Yukui

    2011-01-01

    Surface integrity changes of TA2 pure titanium including surface topography, microstructure and nanohardness distribution along surface layer were investigated by different techniques of low energy high current pulsed electron beam treatments (LEHCPEBTs). The surface topography was characterized by SEM. Moreover, the TEM observation and X-ray diffraction analysis were performed to reveal the surface modification mechanism of TA2 pure titanium by LEHCPEBTs. The surface roughness was modified by electron beam treatment and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM and TEM. The results show that the surface finish obtains good polishing quality and there is no phase transformation but the dislocations by LEHCPEBT. Furthermore, the nanohardness in the surface modified layer is improved. The remelt and fine-grain microstructure of surface layer caused by LEHCPEBTs are the main polishing mechanism and the reason of modification of surface topography and the increment in nanohardness is mainly due to the dislocations and fine grains in the modified layer induced by LEHCPEBT.

  2. Role of Electronic Structure In Ion Band State Theory of Low Energy Nuclear Reactions

    Science.gov (United States)

    Chubb, Scott

    2004-03-01

    The Nuts and Bolts of our Ion Band State (IBS) theory of low energy nuclear reactions (LENR's) in palladium-deuteride (PdD) and palladium-hydride (PdH) are the electrons that hold together or tear apart the bonds (or lack of bonds) between deuterons (d's) or protons (p's) and the host material. In PdDx and PdH_x, this bonding is strongly correlated with loading: in ambient loading conditions (x< 0. 6), the bonding in hibits IBS occupation. As x arrow 1, slight increases and decreases in loading can lead to vibrations (which have conventionally been thought to occur from phonons) that can induce potential losses or increases of p/d. Naive assumptions about phonons fail to include these losses and increases. These effects can occur because neither H or D has core electrons and because in either PdD or PdH, the electrons near the Fermi Energy have negligible overlap with the nucleus of either D or H. I use these ideas to develop a formal justification, based on a generalization of conventional band theory (Scott Chubb, "Semi-Classical Conduction of Charged and Neutral Particles in Finite Lattices," 2004 March Meeting."), for the idea that occupation of IBS's can occur and that this can lead to nuclear reactions.

  3. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    Science.gov (United States)

    Alizadeh, Elahe; Sanche, Léon

    2014-04-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N2, O2, H2O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N2 had little effect on the yields of LEE-induced single and double strand breaks, both O2 and H2O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O2 and H2O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitisation of these agents in chemoradiation cancer therapy.

  4. Validities of three multislice algorithms for quantitative low-energy transmission electron microscopy

    International Nuclear Information System (INIS)

    Ming, W.Q.; Chen, J.H.

    2013-01-01

    Three different types of multislice algorithms, namely the conventional multislice (CMS) algorithm, the propagator-corrected multislice (PCMS) algorithm and the fully-corrected multislice (FCMS) algorithm, have been evaluated in comparison with respect to the accelerating voltages in transmission electron microscopy. Detailed numerical calculations have been performed to test their validities. The results show that the three algorithms are equivalent for accelerating voltage above 100 kV. However, below 100 kV, the CMS algorithm will introduce significant errors, not only for higher-order Laue zone (HOLZ) reflections but also for zero-order Laue zone (ZOLZ) reflections. The differences between the PCMS and FCMS algorithms are negligible and mainly appear in HOLZ reflections. Nonetheless, when the accelerating voltage is further lowered to 20 kV or below, the PCMS algorithm will also yield results deviating from the FCMS results. The present study demonstrates that the propagation of the electron wave from one slice to the next slice is actually cross-correlated with the crystal potential in a complex manner, such that when the accelerating voltage is lowered to 10 kV, the accuracy of the algorithms is dependent of the scattering power of the specimen. - Highlights: • Three multislice algorithms for low-energy transmission electron microscopy are evaluated. • The propagator-corrected algorithm is a good alternative for voltages down to 20 kV. • Below 20 kV, a fully-corrected algorithm has to be employed for quantitative simulations

  5. Bioastrophysical Aspects of Low Energy Ion Irradiation of Frozen Anthracene Containing Water

    International Nuclear Information System (INIS)

    Tuleta, M.; Gabla, L.; Madej, J.

    2001-01-01

    The origin of life on Earth remains a fascinating mystery in spite of many theories existing on this subject. However, it seems that simple prebiotic molecules could play an essential role in the formation of more complex organisms. In our experiment, we synthesized a class of these molecules (quinones) bombarding frozen anthracene containing water with low energy hydrogen ions. This experiment roughly simulated the astrophysical conditions which one can find in the solar system. Thus, we can hypothesize that prebiotic molecules could be created by interaction of the solar wind with interplanetary dust grains. The delivery of these molecules to early Earth may have contributed to the generation of life on our planet

  6. Effects of low energy helium plasma irradiation on potassium doped tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Xiaoyan [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang (China); Huang, Bo [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Liu, Dongping; Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Liu, Ning [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Tang, Jun, E-mail: tangjun@scu.edu.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China)

    2017-04-15

    Effects of helium plasma irradiation on spark plasma sintering (SPS) W-K, pure W and traditionally sintered commercial W-K have been studied, concerning the density, grain size and potassium content as the influence factors. Pinholes are formed under 120 eV He ions at 600 °C and 1 × 10{sup 23} m{sup −2} fluence on the surface of all samples. It is found that SPS-sintered W-K shows the best irradiation resistance among the present samples, and SPS-sintered pure W exhibits higher irradiation tolerance than commercial W-K. Different He-plasma tolerance was observed among the SPS-sintered W-K samples due to varied potassium content and grain size. In addition, the microstructure evolution under helium irradiation, the growth-migration of helium bubbles and their interactions of potassium bubbles have also been discussed.

  7. Scanning of irradiated silicon detectors using $\\alpha$ particles and low energy protons

    CERN Document Server

    Casse, G L; Glaser, M; Kohout, Z; Konícek, J; Lemeilleur, F; Leroy, C; Linhart, V; Mares, J J; Pospísil, S; Roy, P; Sopko, B; Sinor, M; Svejda, J; Vorobel, V; Wilhelm, I

    1999-01-01

    In a spectroscopic study of non-irradiated and proton-irradiated silicon diodes, the detectors were illuminated from the front side and from the rear side by various alpha particle sources (mainly ThC') and by monoenergetic protons with energies from 1.0 to 2.5~MeV. Their response characteristics have been studied as a function of the incoming particle energy and the applied bias voltage. The charge collection efficiency was determined as a function of fluence

  8. The low energy (140 MeV) chemistry facility at the 500 MeV electron accelerator MEA at Amsterdam

    International Nuclear Information System (INIS)

    Brinkman, G.A.; Kapteyn, J.C.; Louwrier, P.W.F.; Lindner, L.; Peelen, B.; Polak, P.; Schimmel, A.; Stock, F.R.; Veenboer, J.T.; Visser, J.

    1980-01-01

    The facility includes the Low Energy Chemistry (LECH) hall equipped with a beam-line for pulse-radiolysis and a second one for the production of radioisotopes and for experiments with electron-free photon beams. It also includes the Low Energy Laboratory (LELAB) containing two chemistry laboratories and a control room. These facilities are also available to outside research groups. (orig./HP)

  9. Dose conversion factors and linear energy transfer for irradiation of thin blood layers with low-energy X rays

    International Nuclear Information System (INIS)

    Verhaegen, F.; Seuntjens, J.

    1994-01-01

    For irradiation of thin samples of biological material with low-energy X rays, conversion of measured air kerma, free in air to average absorbed dose to the sample is necessary. In the present paper, conversion factors from measured air kerma to average absorbed dose in thin blood samples are given for four low-energy X-ray qualities (14-50 kVp). These factors were obtained by Monte Carlo simulation of a practical sample holder. Data for different thicknesses of the blood and backing layer are presented. The conversion factors are found to depend strongly on the thicknesses of the blood layer and backing layer. In radiobiological work, knowledge of linear energy transfer (LET) values for the radiation quality used is often required. Track-averaged LET values for low-energy X rays are presented in this work. It is concluded that the thickness of the sample does not influence the LET value appreciably, indicating that for all radiobiological purposes this value can be regarded as a constant throughout the sample. Furthermore, the large difference between the LET value for a 50 kV spectrum found in this work and the value given in ICRU Report 16 is pointed out. 16 refs., 7 figs., 1 tab

  10. Low energy proton irradiation effects on InP/InGaAs DHBTs and InP-base frequency dividers

    Science.gov (United States)

    Zhang, Xingyao; Li, Yudong; Guo, Qi; Feng, Jie

    2018-03-01

    InP/InGaAs DHBTs and frequency dividers are irradiated by low energy proton, and displacement damage effect of the devices are analyzed. InP/InGaAs DHBTs has been made DC characteristics measurements, and the function measurement for frequency dividers has been done both before and after proton irradiation. The breakdown voltage of InP DHBTs drop to 3.7V When the fluence up to 5x1013 protons/cm2. Meanwhile, the function of frequency dividers get out of order. Degradation of DC characteristics of DHBTs are due to the radiation-induced defects in the quasi neutral base and the space charge region of base-collector and base-emitter junctions. The performance deterioration of DHBTs induce the fault of frequency dividers, and prescaler may be the most sensitive circuit.

  11. Determining neutrino mass hierarchy from electron disappearance at a low energy neutrino factory

    International Nuclear Information System (INIS)

    Raut, Sushant K.

    2013-01-01

    Reactor neutrino experiments have recently measured the value of θ 13 , to be non-zero and moderately large. This makes the determination of the neutrino mass hierarchy possible. However, our lack of knowledge of δ CP results in a parameter degeneracy, which makes this task difficult. The electron neutrino disappearance probability does not depend on δ CP . Therefore, in principle, it is possible to determine the hierarchy independently of δ CP using this channel. Previous studies of neutrino factories have not considered this channel, because the effect of systematics in electron disappearance is substantial. However, we show that for the moderately large value of θ 13 measured, hierarchy determination is possible in spite of systematic effects. We consider a low energy neutrino factory (LENF) setup with a totally active scintillator detector (TASD) with charge-identification. We optimize the setup in muon energy and baseline, for different allowed values of θ 13 and runtime. We find that a LENF with baseline of around 1300 km and muon energy around 3-4 GeV is well suited for hierarchy determination. For the RENO best-fit value of θ 13 , this setup can determine the hierarchy at 5ω, for all values of δ CP and for both hierarchies. (author)

  12. Surface structure of VN0.89(100) determined by low-energy electron diffraction

    International Nuclear Information System (INIS)

    Gauthier, Y.; Joly, Y.; Rundgren, J.; Johansson, L.I.; Wincott, P.

    1990-01-01

    The structure of the (100) surface of substoichiometric vanadium nitride was studied by low-energy electron diffraction on a VN 0.89 (100) sample. A simple 1x1 (100) diffractogram was observed. To describe the electron scattering in substoichiometric VN we apply the averaged t-matrix approximation to the nitrogen atoms. We find that the best structural model is one having no nitrogen vacancies in the surface region. It turns out that the first layer is rippled with the N atoms displaced 0.17 A above the subplane of V atoms, that the spacing between this subplane and the second layer is 1.92 A, and that the spacing between the second and the third layer is 2.08 A. In relation to the (100) spacing of the bulk, 2.06 A, these spacings are 6.8% contracted and 1% expanded, respectively. The Debye temperature of VN is found to be 660 K in good agreement with a prediction from entropy data and from neutron diffraction and helium-ion channeling experiments

  13. Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas

    Science.gov (United States)

    Li, Jun; Zhang, Song Bin; Ye, Bang Jiao; Wang, Jian Guo; Janev, R. K.

    2017-09-01

    Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas have been investigated by employing the exterior complex scaling method. The interactions between charged particles in the plasmas have been represented by Debye-Hückel potentials. The 1 s -1 s elastic collision strengths below the n =2 excitation threshold of He+ dominated by resonance structures are calculated for different screening lengths. As the screening strength increases, the resonance peaks studied [2(1,0) 2 +1Se,3Po,1De , and 2(0,1) 2 +1Po] exhibit blueshifts and then redshifts with a further increase of the screening strength, which results in dramatic changes of the collision strengths. It is found that these dynamic variation features of the resonances are related to the changes of energy levels of He+ in the screened potential and geometric configurations of resonances. Triple-differential-ionization cross sections in coplanar geometries at 6-Ry incident electron energy are also reported, significant changes are observed with varying screening length.

  14. Model of convection mass transfer in titanium alloy at low energy high current electron beam action

    Science.gov (United States)

    Sarychev, V. D.; Granovskii, A. Yu; Nevskii, S. A.; Konovalov, S. V.; Gromov, V. E.

    2017-01-01

    The convection mixing model is proposed for low-energy high-current electron beam treatment of titanium alloys, pre-processed by heterogeneous plasma flows generated via explosion of carbon tape and powder TiB2. The model is based on the assumption vortices in the molten layer are formed due to the treatment by concentrated energy flows. These vortices evolve as the result of thermocapillary convection, arising because of the temperature gradient. The calculation of temperature gradient and penetration depth required solution of the heat problem with taking into account the surface evaporation. However, instead of the direct heat source the boundary conditions in phase transitions were changed in the thermal conductivity equation, assuming the evaporated material takes part in the heat exchange. The data on the penetration depth and temperature distribution are used for the thermocapillary model. The thermocapillary model embraces Navier-Stocks and convection heat transfer equations, as well as the boundary conditions with the outflow of evaporated material included. The solution of these equations by finite elements methods pointed at formation of a multi-vortices structure when electron-beam treatment and its expansion over new zones of material. As the result, strengthening particles are found at the depth exceeding manifold their penetration depth in terms of the diffusion mechanism.

  15. Experimental investigation of electron cooling and stacking of lead ions in a low energy accumulation ring

    CERN Document Server

    Bosser, Jacques; Chanel, M; Hill, C; Lombardi, A M; MacCaferri, R; Maury, S; Möhl, D; Molinari, G; Rossi, S; Tanke, E; Tranquille, G; Vretenar, Maurizio

    1999-01-01

    This report gives the results of a programme of experimental investigations, which were carried out to test stacking of lead ions in a storage ring (the former Low Energy Antiproton Ring, LEAR) at 4.2 MeV per nucleon. The motivation was to demonstrate the feasibility of gaining the large factor in the phase-space density required for injection into the LHC. In the first part of the report, the layout of the experiments is described, the choice of the parameters of the electron cooling system used for stacking is reported and the multi-turn injection using horizontal- and longitudinal- (and in the final project also vertical-) phase space is discussed. In the second part the experimental results are presented. Factors of vital importance are the stacking efficiency, the beam life-time and the cooling time of the ions. The beam decay owing to charge exchange with the residual gas and to recombination by the capture of cooling electrons was intensively studied. Beam instabilities and space-charge effects in the ...

  16. Monte Carlo dose calculation improvements for low energy electron beams using eMC

    International Nuclear Information System (INIS)

    Fix, Michael K; Frei, Daniel; Volken, Werner; Born, Ernst J; Manser, Peter; Neuenschwander, Hans

    2010-01-01

    The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm 2 of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d max and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm 2 at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose calculation

  17. Monte Carlo dose calculation improvements for low energy electron beams using eMC.

    Science.gov (United States)

    Fix, Michael K; Frei, Daniel; Volken, Werner; Neuenschwander, Hans; Born, Ernst J; Manser, Peter

    2010-08-21

    The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm(2) of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d(max) and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm(2) at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose

  18. A novel low energy electron microscope for DNA sequencing and surface analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, M., E-mail: marian@electronoptica.com [Electron Optica Inc., 1000 Elwell Court #110, Palo Alto, CA 94303 (United States); Shadman, K. [Electron Optica Inc., 1000 Elwell Court #110, Palo Alto, CA 94303 (United States); Persson, H.H.J. [Stanford Genome Technology Center, Stanford University School of Medicine, 855 California Avenue, Palo Alto, CA 94304 (United States); N’Diaye, A.T. [Electron Optica Inc., 1000 Elwell Court #110, Palo Alto, CA 94303 (United States); NCEM, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Schmid, A.K. [NCEM, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Davis, R.W. [Stanford Genome Technology Center, Stanford University School of Medicine, 855 California Avenue, Palo Alto, CA 94304 (United States)

    2014-10-15

    Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) is a novel technique that is directed towards imaging nanostructures and surfaces with sub-nanometer resolution. The technique combines a monochromator, a mirror aberration corrector, an energy filter, and dual beam illumination in a single instrument. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. Simulation results predict that the novel aberration corrector design will eliminate the second rank chromatic and third and fifth order spherical aberrations, thereby improving the resolution into the sub-nanometer regime at landing energies as low as one hundred electron-Volts. The energy filter produces a beam that can extract detailed information about the chemical composition and local electronic states of non-periodic objects such as nanoparticles, interfaces, defects, and macromolecules. The dual flood illumination eliminates charging effects that are generated when a conventional LEEM is used to image insulating specimens. A potential application for MAD-LEEM is in DNA sequencing, which requires high resolution to distinguish the individual bases and high speed to reduce the cost. The MAD-LEEM approach images the DNA with low electron impact energies, which provides nucleobase contrast mechanisms without organometallic labels. Furthermore, the micron-size field of view when combined with imaging on the fly provides long read lengths, thereby reducing the demand on assembling the sequence. Experimental results from bulk specimens with immobilized single-base oligonucleotides demonstrate that base specific contrast is available with reflected, photo-emitted, and Auger electrons. Image contrast simulations of model rectangular features mimicking the individual nucleotides in a DNA strand have been developed to translate measurements of contrast on bulk DNA to the detectability of

  19. On artefact-free reconstruction of low-energy (30–250 eV) electron holograms

    Energy Technology Data Exchange (ETDEWEB)

    Latychevskaia, Tatiana, E-mail: tatiana@physik.uzh.ch; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

    2014-10-15

    Low-energy electrons (30–250 eV) have been successfully employed for imaging individual biomolecules. The most simple and elegant design of a low-energy electron microscope for imaging biomolecules is a lensless setup that operates in the holographic mode. In this work we address the problem associated with the reconstruction from the recorded holograms. We discuss the twin image problem intrinsic to inline holography and the problem of the so-called biprism-like effect specific to low-energy electrons. We demonstrate how the presence of the biprism-like effect can be efficiently identified and circumvented. The presented sideband filtering reconstruction method eliminates the twin image and allows for reconstruction despite the biprism-like effect, which we demonstrate on both, simulated and experimental examples. - Highlights: • Radiation damage-free imaging of individual biomolecules. • Elimination of the twin image in inline holograms. • Circumventing biprism-like effect in low-energy electron holograms. • Artefact-free reconstructions of low-energy electron holograms.

  20. On artefact-free reconstruction of low-energy (30–250 eV) electron holograms

    International Nuclear Information System (INIS)

    Latychevskaia, Tatiana; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

    2014-01-01

    Low-energy electrons (30–250 eV) have been successfully employed for imaging individual biomolecules. The most simple and elegant design of a low-energy electron microscope for imaging biomolecules is a lensless setup that operates in the holographic mode. In this work we address the problem associated with the reconstruction from the recorded holograms. We discuss the twin image problem intrinsic to inline holography and the problem of the so-called biprism-like effect specific to low-energy electrons. We demonstrate how the presence of the biprism-like effect can be efficiently identified and circumvented. The presented sideband filtering reconstruction method eliminates the twin image and allows for reconstruction despite the biprism-like effect, which we demonstrate on both, simulated and experimental examples. - Highlights: • Radiation damage-free imaging of individual biomolecules. • Elimination of the twin image in inline holograms. • Circumventing biprism-like effect in low-energy electron holograms. • Artefact-free reconstructions of low-energy electron holograms

  1. Generation of a pulsed low-energy electron beam using the channel spark device

    Energy Technology Data Exchange (ETDEWEB)

    Elgarhy, M. A. I., E-mail: elgarhy@azhar.edu.eg; Hassaballa, S. E.; Rashed, U. M.; ElSabbagh, M. M.; Saudy, A. H. [Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt); Soliman, H. M. [Plasma and Nuclear Fusion Department, Atomic Energy Authority, Enshas (Egypt)

    2015-12-15

    For the generation of low-energy electron beam, the design and characteristics of channel spark discharge (CSD) operating at a low voltage are presented in this paper. The discharge voltage, discharge current, X-ray emissions, and electron beam current were experimentally determined. The effects of the applied voltage, working gas pressure, and external capacitance on the CSD and beam parameters were measured. At an applied voltage of 11 kV, an oxygen gas pressure of 25 mTorr, and an external capacitance of 16.45 nF, the maximum measured current was 900 A. The discharge current increased with the increase in the pressure and capacitance, while its periodic time decreased with the increase in the pressure. Two types of the discharge were identified and recorded: the hollow cathode discharge and the conduction discharge. A Faraday cup was used to measure the beam current. The maximum measured beam current was 120 A, and the beam signal exhibited two peaks. The increase in both the external capacitance and the applied discharge voltage increased the maximum electron beam current. The electron-beam pulse time decreased with the increase in the gas pressure at a constant voltage and increased with the decrease in the applied discharge voltage. At an applied voltage of 11 kV and an oxygen gas pressure of 15 mTorr, the maximum beam energy was 2.8 keV. The X-ray signal intensity decreased with the increase in the gas pressure and increased with the increase in the capacitance.

  2. Colour centres induced in LiF by low-energy electrons

    CERN Document Server

    Baldacchini, G; Montereali, R M; Scacco, A

    1998-01-01

    A detailed study has been carried out on the optical properties of intrinsic colour centres, created in LiF crystals under irradiation with low-penetration 3 keV electrons. The kinetics of the production of F and M centres, determined from optical absorption measurements, exhibits a typical three-stage structure and an evident saturation at high doses. The quantitative evaluation of the kinetic parameters is in excellent agreement with the predictions of the most comprehensive theoretical model. A comparison of the effects of irradiation at different temperatures, determined from absorption and photoluminescence spectra, allows one to deduce the conditions for preferential formation of F sub 2 or F sub 3 sup + defects in LiF crystals. (author)

  3. Electron irradiation of power transistors

    International Nuclear Information System (INIS)

    Hower, P.L.; Fiedor, R.J.

    1982-01-01

    A method for reducing storage time and gain parameters in a semiconductor transistor includes the step of subjecting the transistor to electron irradiation of a dosage determined from measurements of the parameters of a test batch of transistors. Reduction of carrier lifetime by proton bombardment and gold doping is mentioned as an alternative to electron irradiation. (author)

  4. Enhancement of optical absorption of Si (100) surfaces by low energy N+ ion beam irradiation

    Science.gov (United States)

    Bhowmik, Dipak; Karmakar, Prasanta

    2018-05-01

    The increase of optical absorption efficiency of Si (100) surface by 7 keV and 8 keV N+ ions bombardment has been reported here. A periodic ripple pattern on surface has been observed as well as silicon nitride is formed at the ion impact zones by these low energy N+ ion bombardment [P. Karmakar et al., J. Appl. Phys. 120, 025301 (2016)]. The light absorption efficiency increases due to the presence of silicon nitride compound as well as surface nanopatterns. The Atomic Force Microscopy (AFM) study shows the formation of periodic ripple pattern and increase of surface roughness with N+ ion energy. The enhancement of optical absorption by the ion bombarded Si, compared to the bare Si have been measured by UV - visible spectrophotometer.

  5. The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

    Directory of Open Access Journals (Sweden)

    Rachel M. Thorman

    2015-09-01

    Full Text Available Focused electron beam induced deposition (FEBID is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (3, Pt(PF34, Co(CO3NO, and W(CO6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors.

  6. Low-energy electron transmission and secondary-electron emission experiments on crystalline and molten long-chain alkanes

    International Nuclear Information System (INIS)

    Ueno, N.; Sugita, K.; Seki, K.; Inokuchi, H.

    1986-01-01

    This paper describes the results of low-energy electron transmission and secondary-electron emission experiments on thin films of long-chain alkanes deposited on metal substrates. The spectral changes due to crystal-melt phase transition were measured in situ in both experiments. The ground-state energy V 0 of the quasifree electron in crystalline state was determined to be 0.5 +- 0.1 eV. The value of V 0 for the molten state was found to be negative. Further, in the crystalline state evidence is found for a direct correspondence between the transmission maxima and the high value of the density of states in the conduction bands

  7. A method for extraction of crystallography-related information from a data cube of very-low-energy electron micrographs

    Czech Academy of Sciences Publication Activity Database

    Knápek, Alexandr; Pokorná, Zuzana

    2015-01-01

    Roč. 148, JAN 2015 (2015), s. 52-56 ISSN 0304-3991 R&D Projects: GA MŠk(CZ) LO1212 Keywords : Very low energy * Scanning electron microscopy * SLEEM * Data cube * Image processing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.874, year: 2015

  8. Na,K-ATPase biostimulation by low-energy laser irradiation: comparative effects in membrane, solubilized and proteoliposomes enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Rigos, C.F.; Tedesco, A.C.; Ciancaglini, P. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Quimica; Santos, H.L. [Universidade Federal de Sao Joao Del Rei (UFSJ), MG (Brazil)

    2008-07-01

    Full text: The mechanism of laser irradiation action on living cells is not yet understood. The role of membrane ATPases as possible targets has been analyzed. In our group we have been working with Na,K-ATPase. This enzyme is a member of the P-type family of active cation transport proteins. Thus, the aim of the present work was to investigate the effect of low-energy laser irradiation (685 nm, 35 mW) on the ATPase activity of different forms of the Na,K-ATPase. Membrane-bound and solubilized (ab)2 form of Na,K-ATPase was obtained from the rabbit kidney and DPPC:DPPE-proteoliposomes were prepared by the co-solubilization method. Irradiations were carried out at 685 nm. The ATPase activity of the membrane fraction was not altered with exposition to irradiation doses between 4 and 24 J/c m2. With irradiation doses ranging from 32 to 40 J/c m2, a 28% increase on the ATPase activity was observed while when using up to 50 J/c m2 no additional enhancement was observed. When bio stimulation was done using the purified or the reconstituted enzyme, an increase of about 36-40% on the ATPase activity was observed using only 4-8 J/c m2. With irradiation above these values (24 J/c m2) no additional increase in the activity appeared. These studies revealed that the bio stimulation of ATPase activity from different forms of the Na,K -ATPase is dose dependent in different ranges of irradiation exposure. The stimulation promoted by visible laser doses was modulated and the process was reverted after 2 h for the enzyme present in the membrane and after about 5 h for the solubilized or the reconstituted in DPPC:DPPE-liposomes.

  9. Na,K-ATPase biostimulation by low-energy laser irradiation: comparative effects in membrane, solubilized and proteoliposomes enzyme

    International Nuclear Information System (INIS)

    Rigos, C.F.; Tedesco, A.C.; Ciancaglini, P.

    2008-01-01

    Full text: The mechanism of laser irradiation action on living cells is not yet understood. The role of membrane ATPases as possible targets has been analyzed. In our group we have been working with Na,K-ATPase. This enzyme is a member of the P-type family of active cation transport proteins. Thus, the aim of the present work was to investigate the effect of low-energy laser irradiation (685 nm, 35 mW) on the ATPase activity of different forms of the Na,K-ATPase. Membrane-bound and solubilized (ab)2 form of Na,K-ATPase was obtained from the rabbit kidney and DPPC:DPPE-proteoliposomes were prepared by the co-solubilization method. Irradiations were carried out at 685 nm. The ATPase activity of the membrane fraction was not altered with exposition to irradiation doses between 4 and 24 J/c m2. With irradiation doses ranging from 32 to 40 J/c m2, a 28% increase on the ATPase activity was observed while when using up to 50 J/c m2 no additional enhancement was observed. When bio stimulation was done using the purified or the reconstituted enzyme, an increase of about 36-40% on the ATPase activity was observed using only 4-8 J/c m2. With irradiation above these values (24 J/c m2) no additional increase in the activity appeared. These studies revealed that the bio stimulation of ATPase activity from different forms of the Na,K -ATPase is dose dependent in different ranges of irradiation exposure. The stimulation promoted by visible laser doses was modulated and the process was reverted after 2 h for the enzyme present in the membrane and after about 5 h for the solubilized or the reconstituted in DPPC:DPPE-liposomes

  10. Modulation transfer function and detective quantum efficiency of electron bombarded charge coupled device detector for low energy electrons

    International Nuclear Information System (INIS)

    Horacek, Miroslav

    2005-01-01

    The use of a thinned back-side illuminated charge coupled device chip as two-dimensional sensor working in direct electron bombarded mode at optimum energy of the incident signal electrons is demonstrated and the measurements of the modulation transfer function (MTF) and detective quantum efficiency (DQE) are described. The MTF was measured for energy of electrons 4 keV using an edge projection method and a stripe projection method. The decrease of the MTF for a maximum spatial frequency of 20.8 cycles/mm, corresponding to the pixel size 24x24 μm, is 0.75≅-2.5 dB, and it is approximately the same for both horizontal and vertical directions. DQE was measured using an empty image and the mixing factor method. Empty images were acquired for energies of electrons from 2 to 5 keV and for various doses, ranging from nearly dark image to a nearly saturated one. DQE increases with increasing energy of bombarded electrons and reaches 0.92 for electron energy of 5 keV. For this energy the detector will be used for the angle- and energy-selective detection of signal electrons in the scanning low energy electron microscope

  11. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Rezaee, Mohammad, E-mail: Mohammad.Rezaee@USherbrooke.ca; Hunting, Darel J.; Sanche, Léon [Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4 (Canada)

    2014-07-15

    Purpose: The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods: Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by{sup 125}I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results: For a single decay of{sup 125}I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm{sup 3} volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions: Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should

  12. Analytical solutions for thermal transient profile in solid target irradiated with low energy and high beam current protons

    International Nuclear Information System (INIS)

    Oliveira, Henrique B. de; Brazao, Nei G.; Sciani, Valdir

    2009-01-01

    There were obtained analytical solutions for thermal transient in solid targets, used in short half-life radioisotopes production, when irradiated with low energy and high beam current protons, in the cyclotron accelerator Cyclone 30 of the Institute for Energy and Nuclear Research (IPEN/CNEN-SP). The beam spatial profile was considered constant and the time depended heat distribution equation was resolved for a continuous particles flow entering the target. The problem was divided into two stages: a general solution was proposed which is the sum of two functions, the first one related to the thermal equilibrium situation and the second one related to a time dependent function that was determinate by the setting of the contour conditions and the initial conditions imposed by the real problem. By that one got an analytic function for a complete description of the heat transport phenomenon inside the targets. There were used both, numerical and symbolic computation methods, to obtain temperature maps and thermal gradients and the results showed an excellent agreement when compared with purely numerical models. The results were compared with obtained data from Gallium-67 and Thallium-201 irradiation routines conducted by the IPEN Cyclotrons accelerators center, showing excellent agreement. The objective of this paper is to develop solid targets irradiation systems (metals and oxides) so that one can operate with high levels of current beam, minimizing the irradiation time and maximizing the final returns. (author)

  13. PLEASE: The Python Low-energy Electron Analysis SuitE – Enabling Rapid Analysis of LEEM and LEED Data

    Directory of Open Access Journals (Sweden)

    Maxwell Grady

    2018-02-01

    Full Text Available PLEASE, the Python Low-energy Electron Analysis SuitE, provides an open source and cross-platform graphical user interface (GUI for rapid analysis and visualization of low energy electron microscopy (LEEM data sets. LEEM and the associated technique, selected area micro-spot low energy electron diffraction (μ-LEED, are powerful tools for analysis of the surface structure for many novel materials. Specifically, these tools are uniquely suited for the characterization of two-dimensional materials. PLEASE offers a user-friendly point-and-click method for extracting intensity-voltage curves from LEEM and LEED data sets. Analysis of these curves provides insight into the atomic structure of the target material surface with unparalleled resolution.

  14. Smoothing an isolated interface of cobalt-copper under irradiation by low-energy argon ions

    International Nuclear Information System (INIS)

    Stognij, A.I.; Novitskij, N.N.; Stukalov, O.M.

    2003-01-01

    Multilayer film structures, i.e. gold layer-copper-cobalt, are considered. It is shown that the structure, where cobalt surface prior to copper layer deposition was subjected to additional irradiation by a flow of argon ions, features the smoothest surface. The conclusion is made about smoothing out of cobalt-copper interface as a result of multiple collisions of argon slow ions and cobalt atoms during braking within two or three upper atomic rows of the cobalt layer [ru

  15. A low-energy x-ray irradiator for electrophysiological studies

    International Nuclear Information System (INIS)

    Schauer, D.A.; Zeman, G.H.; Pellmar, T.C.

    1989-01-01

    A 50 kVp molybdenum target/filter x-ray tube has been installed inside a lead-shielded Faraday cage. High-dose rates of up to 1.54 Gy min -1 (17.4 keV weighted average photons) have been used to conduct local in vitro irradiations of the hippocampal region of guinea pig brains. Electrophysiological recordings of subtle changes in neuronal activity indicate this system is suitable for this application. (author)

  16. Effect of neutron irradiation on the density of low-energy excitations in vitreous silica

    International Nuclear Information System (INIS)

    Smith, T.L.

    1979-01-01

    Systematic low-temperature measurements of the thermal conductivity, specific heat, dielectric constant, and temperature-dependent ultrasound velocity were made on a single piece of vitreous silica. These measurements were repeated after fast neutron irradiation of the material. It was found that the irradiation produced changes of the same relative magnitude in the low-temperature excess specific heat C/sub ex/, the thermal conductivity kappa, and the anomalous temperature dependence of the ultrasound velocity Δv/v. A corresponding change in the temperature dependent dielectric constant was not observed. It is therefore likely that kappa and Δv/v are determined by the same localized excitations responsible for C/sub ex/, but the temperature dependence of the dielectric constant may have a different, though possibly related, origin. A consistent account for the measured C/sub ex/, kappa, and Δv/v of unirradiated silica is given by the tunneling-state model with a single, energy-dependent density of states. Changes in these three properties due to irradiation can be explained by altering only the density of tunneling states incorporated in the model

  17. Structure of ultrathin Pd films determined by low-energy electron microscopy and diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Santos, B; De la Figuera, J [Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Puerta, J M; Cerda, J I [Instituto de Ciencia de Materiales, CSIC, Madrid 28049 (Spain); Herranz, T [Instituto de Quimica-Fisica ' Rocasolano' , CSIC, Madrid 28006 (Spain); McCarty, K F [Sandia National Laboratories, Livermore, CA 94550 (United States)], E-mail: benitosantos001@gmail.com

    2010-02-15

    Palladium (Pd) films have been grown and characterized in situ by low-energy electron diffraction (LEED) and microscopy in two different regimes: ultrathin films 2-6 monolayers (ML) thick on Ru(0001), and {approx}20 ML thick films on both Ru(0001) and W(110). The thinner films are grown at elevated temperature (750 K) and are lattice matched to the Ru(0001) substrate. The thicker films, deposited at room temperature and annealed to 880 K, have a relaxed in-plane lattice spacing. All the films present an fcc stacking sequence as determined by LEED intensity versus energy analysis. In all the films, there is hardly any expansion in the surface-layer interlayer spacing. Two types of twin-related stacking sequences of the Pd layers are found on each substrate. On W(110) the two fcc twin types can occur on a single substrate terrace. On Ru(0001) each substrate terrace has a single twin type and the twin boundaries replicate the substrate steps.

  18. Low-Energy Electron Potentiometry: Contactless Imaging of Charge Transport on the Nanoscale.

    Science.gov (United States)

    Kautz, J; Jobst, J; Sorger, C; Tromp, R M; Weber, H B; van der Molen, S J

    2015-09-04

    Charge transport measurements form an essential tool in condensed matter physics. The usual approach is to contact a sample by two or four probes, measure the resistance and derive the resistivity, assuming homogeneity within the sample. A more thorough understanding, however, requires knowledge of local resistivity variations. Spatially resolved information is particularly important when studying novel materials like topological insulators, where the current is localized at the edges, or quasi-two-dimensional (2D) systems, where small-scale variations can determine global properties. Here, we demonstrate a new method to determine spatially-resolved voltage maps of current-carrying samples. This technique is based on low-energy electron microscopy (LEEM) and is therefore quick and non-invasive. It makes use of resonance-induced contrast, which strongly depends on the local potential. We demonstrate our method using single to triple layer graphene. However, it is straightforwardly extendable to other quasi-2D systems, most prominently to the upcoming class of layered van der Waals materials.

  19. Low energy electron stimulated desorption from DNA films dosed with oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Mirsaleh-Kohan, Nasrin; Bass, Andrew D.; Cloutier, Pierre; Massey, Sylvain; Sanche, Leon [Groupe en sciences des radiations, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, Quebec J1H 5N4 (Canada)

    2012-06-21

    Desorption of anions stimulated by 1-18 eV electron impact on self-assembled monolayer (SAM) films of single DNA strands is measured as a function of film temperature (50-250 K). The SAMs, composed of 10 nucleotides, are dosed with O{sub 2}. The OH{sup -} desorption yields increase markedly with exposure to O{sub 2} at 50 K and are further enhanced upon heating. In contrast, the desorption yields of O{sup -}, attributable to dissociative electron attachment to trapped O{sub 2} molecules decrease with heating. Irradiation of the DNA films prior to the deposition of O{sub 2} shows that this surprising increase in OH{sup -} desorption, at elevated temperatures, arises from the reaction of O{sub 2} with damaged DNA sites. These results thus appear to be a manifestation of the so-called 'oxygen fixation' effect, well known in radiobiology.

  20. Design and commissioning of an aberration-corrected ultrafast spin-polarized low energy electron microscope with multiple electron sources.

    Science.gov (United States)

    Wan, Weishi; Yu, Lei; Zhu, Lin; Yang, Xiaodong; Wei, Zheng; Liu, Jefferson Zhe; Feng, Jun; Kunze, Kai; Schaff, Oliver; Tromp, Ruud; Tang, Wen-Xin

    2017-03-01

    We describe the design and commissioning of a novel aberration-corrected low energy electron microscope (AC-LEEM). A third magnetic prism array (MPA) is added to the standard AC-LEEM with two prism arrays, allowing the incorporation of an ultrafast spin-polarized electron source alongside the standard cold field emission electron source, without degrading spatial resolution. The high degree of symmetries of the AC-LEEM are utilized while we design the electron optics of the ultrafast spin-polarized electron source, so as to minimize the deleterious effect of time broadening, while maintaining full control of electron spin. A spatial resolution of 2nm and temporal resolution of 10ps (ps) are expected in the future time resolved aberration-corrected spin-polarized LEEM (TR-AC-SPLEEM). The commissioning of the three-prism AC-LEEM has been successfully finished with the cold field emission source, with a spatial resolution below 2nm. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Nonlinear saturation of wave packets excited by low-energy electron horseshoe distributions.

    Science.gov (United States)

    Krafft, C; Volokitin, A

    2013-05-01

    Horseshoe distributions are shell-like particle distributions that can arise in space and laboratory plasmas when particle beams propagate into increasing magnetic fields. The present paper studies the stability and the dynamics of wave packets interacting resonantly with electrons presenting low-energy horseshoe or shell-type velocity distributions in a magnetized plasma. The linear instability growth rates are determined as a function of the ratio of the plasma to the cyclotron frequencies, of the velocity and the opening angle of the horseshoe, and of the relative thickness of the shell. The nonlinear stage of the instability is investigated numerically using a symplectic code based on a three-dimensional Hamiltonian model. Simulation results show that the dynamics of the system is mainly governed by wave-particle interactions at Landau and normal cyclotron resonances and that the high-order normal cyclotron resonances play an essential role. Specific features of the dynamics of particles interacting simultaneously with two or more waves at resonances of different natures and orders are discussed, showing that such complex processes determine the main characteristics of the wave spectrum's evolution. Simulations with wave packets presenting quasicontinuous spectra provide a full picture of the relaxation of the horseshoe distribution, revealing two main phases of the evolution: an initial stage of wave energy growth, characterized by a fast filling of the shell, and a second phase of slow damping of the wave energy, accompanied by final adjustments of the electron distribution. The influence of the density inhomogeneity along the horseshoe on the wave-particle dynamics is also discussed.

  2. Calculation on spectrum of direct DNA damage induced by low-energy electrons including dissociative electron attachment.

    Science.gov (United States)

    Liu, Wei; Tan, Zhenyu; Zhang, Liming; Champion, Christophe

    2017-03-01

    In this work, direct DNA damage induced by low-energy electrons (sub-keV) is simulated using a Monte Carlo method. The characteristics of the present simulation are to consider the new mechanism of DNA damage due to dissociative electron attachment (DEA) and to allow determining damage to specific bases (i.e., adenine, thymine, guanine, or cytosine). The electron track structure in liquid water is generated, based on the dielectric response model for describing electron inelastic scattering and on a free-parameter theoretical model and the NIST database for calculating electron elastic scattering. Ionization cross sections of DNA bases are used to generate base radicals, and available DEA cross sections of DNA components are applied for determining DNA-strand breaks and base damage induced by sub-ionization electrons. The electron elastic scattering from DNA components is simulated using cross sections from different theoretical calculations. The resulting yields of various strand breaks and base damage in cellular environment are given. Especially, the contributions of sub-ionization electrons to various strand breaks and base damage are quantitatively presented, and the correlation between complex clustered DNA damage and the corresponding damaged bases is explored. This work shows that the contribution of sub-ionization electrons to strand breaks is substantial, up to about 40-70%, and this contribution is mainly focused on single-strand break. In addition, the base damage induced by sub-ionization electrons contributes to about 20-40% of the total base damage, and there is an evident correlation between single-strand break and damaged base pair A-T.

  3. Behavior of carbon readsorbed on tungsten during low energy Ar ion irradiation at elevated temperatures

    International Nuclear Information System (INIS)

    Pranevicius, L.; Pranevicius, L.L.; Milcius, D.; Templier, C.; Bobrovaite, B.

    2008-01-01

    A study of the behavior of carbon sputtered and readsorbed after scattering collisions with particles of surrounding gas on the tungsten surface affected by Ar ion irradiation with the flux equal to 2 x 10 16 cm -2 s -1 extracted from plasma under 300 V negative bias voltage in the temperature range 370-870 K was performed. The dependence of the W sample weight change on the working gas pressure in the range 0.1-10 Pa was registered and the information was deduced about prevailing sputtering-redeposition processes. The depth profiles of carbon at the tungsten surface were measured. We found that carbon distribution profiles in tungsten depend on the C redeposition rate for fixed ion irradiation parameters. Three regimes have been distinguished: (i) at working gas pressure equal to 5 Pa and more, the C redeposition rate prevails the sample surface erosion rate and the W surface is covered by continuous amorphous carbon film (the C film growth regime), (ii) at working gas pressure equal to about 1 Pa, the C redepostion rate is approximately equal to the erosion rate and the W surface is partially covered by redeposited carbon, and (iii) at working gas pressure less than 0.2 Pa, the erosion rate prevails the C redeposition rate (the W surface erosion regime). In the regime of balanced redeposition and erosion deep C penetration depth into nanocrystalline W was registered. It is suggested that under simultaneous C adsorption and ion irradiation at elevated temperature C adatoms are driven from the W surface into grain boundaries and into the bulk by the difference in chemical potentials between the activated W surface and grain boundaries. As the W surface is covered by amorphous C film, the grain boundaries are blocked and the efficiency of carbon transport decreases

  4. Momenta of particles emitted by target at intensive irradiation by low-energy ions

    CERN Document Server

    Beshenkov, V G; Marchenko, V A

    2002-01-01

    One measured the aggregate momenta of the target emitted particles at the intensive sputtering by E sub 0 approx = 0.5 keV energy heavy inert gases. For liquid and being under premelting temperature Ga target the measured values are close to the expected momenta of sputtered metallic atoms and reflection ions, for Cu and Zr targets they are essentially higher. One assumes that sputtering of atoms of gas-diffuser implanted into the target causes the surplus momentum. The estimated average energy of these atoms approx = 20 eV. Under Ga irradiation the implanted atoms diffuse mainly towards the surface and are desorbed

  5. Improved age-diffusion model for low-energy electron transport in solids. II. Application to secondary emission from aluminum

    International Nuclear Information System (INIS)

    Dubus, A.; Devooght, J.; Dehaes, J.C.

    1987-01-01

    The ''improved age-diffusion'' model for secondary-electron transport is applied to aluminum. Electron cross sections for inelastic collisions with the free-electron gas using the Lindhard dielectric function and for elastic collisions with the randomly distributed ionic cores are used in the calculations. The most important characteristics of backward secondary-electron emission induced by low-energy electrons on polycrystalline Al targets are calculated and compared to experimental results and to Monte Carlo calculations. The model appears to predict the electronic yield, the energy spectra, and the spatial dependence of secondary emission with reasonable accuracy

  6. A track length estimator method for dose calculations in low-energy X-ray irradiations. Implementation, properties and performance

    Energy Technology Data Exchange (ETDEWEB)

    Baldacci, F.; Delaire, F.; Letang, J.M.; Sarrut, D.; Smekens, F.; Freud, N. [Lyon-1 Univ. - CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Centre Leon Berard (France); Mittone, A.; Coan, P. [LMU Munich (Germany). Dept. of Physics; LMU Munich (Germany). Faculty of Medicine; Bravin, A.; Ferrero, C. [European Synchrotron Radiation Facility, Grenoble (France); Gasilov, S. [LMU Munich (Germany). Dept. of Physics

    2015-05-01

    The track length estimator (TLE) method, an 'on-the-fly' fluence tally in Monte Carlo (MC) simulations, recently implemented in GATE 6.2, is known as a powerful tool to accelerate dose calculations in the domain of low-energy X-ray irradiations using the kerma approximation. Overall efficiency gains of the TLE with respect to analogous MC were reported in the literature for regions of interest in various applications (photon beam radiation therapy, X-ray imaging). The behaviour of the TLE method in terms of statistical properties, dose deposition patterns, and computational efficiency compared to analogous MC simulations was investigated. The statistical properties of the dose deposition were first assessed. Derivations of the variance reduction factor of TLE versus analogous MC were carried out, starting from the expression of the dose estimate variance in the TLE and analogous MC schemes. Two test cases were chosen to benchmark the TLE performance in comparison with analogous MC: (i) a small animal irradiation under stereotactic synchrotron radiation therapy conditions and (ii) the irradiation of a human pelvis during a cone beam computed tomography acquisition. Dose distribution patterns and efficiency gain maps were analysed. The efficiency gain exhibits strong variations within a given irradiation case, depending on the geometrical (voxel size, ballistics) and physical (material and beam properties) parameters on the voxel scale. Typical values lie between 10 and 103, with lower levels in dense regions (bone) outside the irradiated channels (scattered dose only), and higher levels in soft tissues directly exposed to the beams.

  7. Temperature-dependent surface porosity of Nb{sub 2}O{sub 5} under high-flux, low-energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Novakowski, T.J., E-mail: tnovakow@purdue.edu; Tripathi, J.K.; Hosinski, G.M.; Joseph, G.; Hassanein, A.

    2016-01-30

    Graphical abstract: - Highlights: • Nb{sub 2}O{sub 5} surfaces are nanostructured with a novel He{sup +} ion irradiation process. • High-flux, low energy He{sup +} ion irradiation generates highly porous surfaces. • Top-down approach guarantees good contact between different crystallites. • Sample annealing demonstrates temperature effect on surface morphology. • Surface pore diameter increases with increasing temperature. - Abstract: The present study reports on high-flux, low-energy He{sup +} ion irradiation as a novel method of enhancing the surface porosity and surface area of naturally oxidized niobium (Nb). Our study shows that ion-irradiation-induced Nb surface micro- and nano-structures are highly tunable by varying the target temperature during ion bombardment. Mirror-polished Nb samples were irradiated with 100 eV He{sup +} ions at a flux of 1.2 × 10{sup 21} ions m{sup −2} s{sup −1} to a total fluence of 4.3 × 10{sup 24} ions m{sup −2} with simultaneous sample annealing in the temperature range of 773–1223 K to demonstrate the influence of sample temperature on the resulting Nb surface morphology. This surface morphology was primarily characterized using field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Below 923 K, Nb surfaces form nano-scale tendrils and exhibit significant increases in surface porosity. Above 923 K, homogeneously populated nano-pores with an average diameter of ∼60 nm are observed in addition to a smaller population of sub-micron sized pores (up to ∼230 nm in diameter). Our analysis shows a significant reduction in surface pore number density and surface porosity with increasing sample temperature. High-resolution ex situ X-ray photoelectron spectroscopy (XPS) shows Nb{sub 2}O{sub 5} phase in all of the ion-irradiated samples. To further demonstrate the length scales in which radiation-induced surface roughening occurs, optical reflectivity was performed over a spectrum of

  8. Application of electron beam irradiation, (1). Development and application of electron beam processors

    International Nuclear Information System (INIS)

    Katsumura, Yosuke

    1994-01-01

    This paper deals with characteristics, equipment (principle and kinds), present conditions, and future issues in the application of electron beam irradiation. Characteristics of electron beams are described in terms of the following: chemical and biological effects of radiation; energy and penetrating power of electron beams; and principle and kinds of electron beam accelerator. Industrial application of electron beam irradiation has advantages of high speed procedure and producibility, less energy, avoidance of poisonous gas, and extreme reduction of organic solvents to be used. The present application of electron beam irradiation cen be divided into the following: (1) hardening of resin or coated membrane; (2) improvement of macromolecular materials; (3) environmental protection; (4) sterilization; (5) food sterilization. The present equipment for electron beam irradiation is introduced according to low energy, medium energy, and high energy equipment. Finally, future issues focuses on (1) the improvement of traceability system and development of electron dosimetric techniques and (2) food sterilization. (N.K.)

  9. Novel phenomena in clusters irradiated by short-wavelength free-electron lasers

    International Nuclear Information System (INIS)

    Fukuzawa, Hironobu; Ueda, Kiyoshi

    2017-01-01

    By electron spectroscopy, we investigated various phenomena that are caused by the irradiation of extreme ultraviolet (EUV) and X-ray free-electron laser (FEL) pulses on rare-gas clusters. The results for the Ne clusters, which were irradiated by EUVFEL pulses at a photon energy of 20.3 eV below the ionization threshold, illustrate that novel interatomic processes yield low-energy electrons. The results for the Xe clusters, irradiated by EUVFEL pulses at a photon energy of 24.3 eV above the threshold, illustrate that nanoplasma is formed as a result of trapping the photoelectrons and consequently emits low-energy thermal electrons. The results for the Ar clusters irradiated by 5 keV XFEL pulses illustrate that nanoplasma is formed by trapping low-energy Auger electrons and secondary electrons in the tens of fs range, and continuous thermal emission from the plasma occurs in the ps range. (author)

  10. A comparison of the relative biological effectiveness of low energy electronic brachytherapy sources in breast tissue: a Monte Carlo study.

    Science.gov (United States)

    White, Shane A; Reniers, Brigitte; de Jong, Evelyn E C; Rusch, Thomas; Verhaegen, Frank

    2016-01-07

    Electronic brachytherapy sources use low energy photons to treat the tumor bed during or after breast-conserving surgery. The relative biological effectiveness of two electronic brachytherapy sources was explored to determine if spectral differences due to source design influenced radiation quality and if radiation quality decreased with distance in the breast. The RBE was calculated through the number of DNA double strand breaks (RBEDSB) using the Monte Carlo damage simulator (MCDS) in combination with other Monte Carlo electron/photon spectrum calculations. 50kVp photons from the Intrabeam (Carl Zeiss Surgical) and Axxent (Xoft) through 40-mm spherical applicators were simulated to account for applicator and tissue attenuation in a variety of breast tissue compositions. 40kVp Axxent photons were also simulated. Secondary electrons (known to be responsible for most DNA damage) spectra at different distance were inputted into MCDS to calculate the RBEDSB. All RBEDSB used a cobalt-60 reference. RBEDSB data was combined with corresponding average photon spectrum energy for the Axxent and applied to model-based average photon energy distributions to produce an RBEDSB map of an accelerated partial breast irradiation (APBI) patient. Both Axxent and Intrabeam 50kVp spectra were shown to have a comparable RBEDSB of between 1.4 and 1.6 at all distances in spite of progressive beam hardening. The Axxent 40kVp also demonstrated a similar RBEDSB at distances. Most RBEDSB variability was dependent on the tissue type as was seen in rib (RBEDSB  ≈  1.4), gland (≈1.55), adipose (≈1.59), skin (≈1.52) and lung (≈1.50). RBEDSB variability between both sources was within 2%. A correlation was shown between RBEDSB and average photon energy and used to produce an RBEDSB map of a dose distribution in an APBI patient dataset. Radiation quality is very similar between electronic brachytherapy sources studied. No significant reductions in RBEDSB were observed with

  11. Track reconstruction method in a small volume self-shunted streamer chamber - analysis of the errors for low energy electrons

    International Nuclear Information System (INIS)

    Parizet, M.J.; Augerat, J.; Avan, M.; Ballet, M.; Vialle, M.

    1977-01-01

    A programme has been worked out to reconstruct electron tracks of low energy (from 100 keV to 2 MeV) curved by a magnetic field in a small streamer chamber (size 10x11x51 cm 3 ). Before a study of the problems involved in the experimental set-up, the geometrical programme is described and the different errors are evaluated. Finally the accuracies on kinetic energies and angles which can be obtained for low energy elctron tracks are given. (Auth.)

  12. Effects of non-implantation factors on survival rate of microbe irradiated by low-energy N+

    International Nuclear Information System (INIS)

    Yang Tianyou; Chen Linhai; Qin Guangyong; Li Zongwei; Su Mingjie; Wang Yanping; Chang Shenghe; Huo Yuping; Li Zongyi

    2006-01-01

    The effects of non-implantation factors, such as drying, vacuum and the staying time of the E.coli LE392 culture, on survival rate of E.coli LE392 were studied when E.coli LE392 was irradiated by the low-energy N + . The results show that the survival rate of E.coli LE392 does not reduce steadily all the time but rapidly drops sometime during drying. The survival rate of E.coli LE392 declines sharply as the samples are placed in vacuum, then falls in distinctively with increasing of time. the tolerance of E.coli LE392 towards vacuum increasingly strengthens when the E.coli LE392 culture is placed at room temperature. Preparing the culture in batchs can ensure the consistency of the irradiated samples and avoid errors caused by the inconsistent samples. When the non-implantation factors are controlled, E.coli is implanted by 30 kev N + of 1 x 10 14 cm -2 and 3 x 10 15 cm -2 , respectively. And the results show no difference in the E.coli's survival rates between batchs at the same dose. (authors)

  13. The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

    International Nuclear Information System (INIS)

    Tripathi, J.K.; Novakowski, T.J.; Gonderman, S.; Bharadwaj, N.; Hassanein, A.

    2016-01-01

    We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He + ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C + ion impurities in He + ion irradiations. For introducing such tiny C + ion impurities, gas mixtures of He and CH 4 have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He + ion (for Mo fuzz growth due to only He + ions) and 100% H + ion (for confirming the significance of tiny 0.04–2.0% H + ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 × 10 24  ions m −2 ), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He + ion irradiation case. Enhancement of C + ion impurities in He + ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C + ion impurity concentrations. Additionally, no fuzz formation for 100% H + ion irradiation at all, were seen (apart from some tiny nano-structuring, in very limited regions). This indicates that there is no significant role of H + ions in Mo fuzz evolutions (at least for such tiny amount, 0.04–2.0% H + ions). The study is significant to understand the behavior of potential high-Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications. - Highlights: • Mo Fuzz evolutions due to low-energy high-flux 100% He + ion irradiation. • Sequential reduction in Mo fuzz evolutions with increasing C + ion impurities in He + ions. • Almost complete prevention of Mo fuzz evolutions for 0.5% C + ion impurity in He + ions. • No Mo fuzz formation for 100% H + ion

  14. Transport of low energy electrons in water and some physico-chemical implications

    International Nuclear Information System (INIS)

    Brenner, D.J.; Zaider, M.

    1983-01-01

    Considerable effort by numerous groups is currently being devoted to measuring or calculating cross-sections for use as input to Monte-Carlo studies of radiation effects. We address the question of how well do low-energy cross-sections need to be known in order to calculate adequately quantities of interest in the radiobiological domain. 11 references, 4 figures

  15. On the idea of low-energy nuclear reactions in metallic lattices by producing neutrons from protons capturing "heavy" electrons

    Science.gov (United States)

    Tennfors, Einar

    2013-02-01

    The present article is a critical comment on Widom and Larsens speculations concerning low-energy nuclear reactions (LENR) based on spontaneous collective motion of protons in a room temperature metallic hydride lattice producing oscillating electric fields that renormalize the electron self-energy, adding significantly to the effective electron mass and enabling production of low-energy neutrons. The frequency and mean proton displacement estimated on the basis of neutron scattering from protons in palladium and applied to the Widom and Larsens model of the proton oscillations yield an electron mass enhancement less than one percent, far below the threshold for the proposed neutron production and even farther below the mass enhancement obtained by Widom and Larsen assuming a high charge density. Neutrons are not stopped by the Coulomb barrier, but the energy required for the neutron production is not low.

  16. Interaction of atomic and low-energy deuterium with tungsten pre-irradiated with self-ions

    International Nuclear Information System (INIS)

    Ogorodnikova, O. V.; Markelj, S.; Toussaint, U. von

    2016-01-01

    Polycrystalline tungsten (W) specimens were pre-irradiated with self-ions to create identical samples with high density of defects up to ∼2.5 μm near the surface. Then, W specimens were exposed to either thermal atomic deuterium (D) beam with an incident energy of ∼0.2 eV or low energy D plasma with the incident energy varied between 5 and 200 eV at different sample temperatures. Each sample was exposed once at certain temperature and fluence. The D migration and accumulation in W were studied post-mortem by nuclear reaction method. It was shown that the rate of the D to occupy radiation-induced defects increases with increasing the incident energy, ion flux, and temperature. Experimental investigation was accompanied by modelling using the rate-equation model. Moreover, the analytical model was developed and benchmarked against numerical model. The calculations of the deuterium diffusion with trapping at radiation-induced defects in tungsten by analytical model are consistent with numerical calculations using rate-equation model. The data of reflection and penetration of atomic and low-energy D were taking from calculations using molecular dynamics (MD) with Juslin interatomic potentials and a binary collision code TRIM. MD calculations show an agreement with a binary collision code TRIM only in a very narrow range of deuterium energies between 1 and 20 eV. Incorporation of the data of reflection and penetration of deuterium in the macroscopic modelling has been done to verify the range of validity of calculations using MD and binary collision code TRIM by comparison of modelling results with experimental data. Modelling results are consistent with experiments using reflection and penetration data of D obtained from TRIM code for incident ion energy above 1 eV. Otherwise, the parameters obtained from MD should be incorporated in the rate-equation model to have a good agreement with the experiments

  17. A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides - The effect of the radiosensitizer 5-fluorouracil

    International Nuclear Information System (INIS)

    Rackwitz, J.; Rankovic, M.L.; Milosavljevic, A.R.; Bald, I.

    2017-01-01

    Low-energy electrons (LEEs) play an important role in DNA radiation damage. Here we present a method to quantify LEE induced strand breakage in well-defined oligonucleotide single strands in terms of absolute cross sections. An LEE irradiation setup covering electron energies <500 eV is constructed and optimized to irradiate DNA origami triangles carrying well-defined oligonucleotide target strands. Measurements are presented for 10.0 and 5.5 eV for different oligonucleotide targets. The determination of absolute strand break cross sections is performed by atomic force microscopy analysis. An accurate fluence determination ensures small margins of error of the determined absolute single strand break cross sections σ SSB . In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil ( 5F U) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of 5F U containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons. (authors)

  18. Low energy spread 100 MeV-1 GeV electron bunches from laser wakefield acceleration at LOASIS

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Esarey, E.; Michel, P.; Nagler, B.; Nakamura, K.; Plateau, G.R.; Schroeder, C.B.; Shadwick, B.A.; Toth, Cs.; Van Tilborg, J.; Leemans, W.P.; Hooker, S.M.; Gonsalves, A.J.; Michel, E.; Cary, J.R.; Bruhwiler, D.

    2006-01-01

    Experiments at the LOASIS laboratory of LBNL recently demonstrated production of 100 MeV electron beams with low energy spread and low divergence from laser wakefield acceleration. The radiation pressure of a 10 TW laser pulse guided over 10 diffraction ranges by a plasma density channel was used to drive an intense plasma wave (wakefield), producing acceleration gradients on the order of 100 GV/m in a mm-scale channel. Beam energy has now been increased from 100 to 1000 MeV by using a cm-scale guiding channel at lower density, driven by a 40TW laser, demonstrating the anticipated scaling to higher beam energies. Particle simulations indicate that the low energy spread beams were produced from self trapped electrons through the interplay of trapping, loading, and dephasing. Other experiments and simulations are also underway to control injection of particles into the wake, and hence improve beam quality and stability further

  19. 15.0 MeV/u He2+ ion-induced low energy electrons from water vapor

    International Nuclear Information System (INIS)

    Okada, Y.; Sato, Y.; Soga, F.; Ohsawa, D.

    2005-01-01

    We present the absolute doubly differential cross sections (DDCS) of low-energy electrons and their angular distributions (20deg - 160deg ) produced in the collisions of 15.0 MeV/u He 2+ ions with water vapor. Details of the experiments by 6.0 and 10.0 MeV/u He 2+ ions were already reported in our previous paper, in which the total uncertainty (±13%) was discussed. This paper shows the absolute DDCS data (1 - 100 eV) by 15.0 MeV/u He 2+ ions, in which the cover surrounding the interaction region was changed to μ-metal from Cu, in order to suppress the residual magnetic field for measuring the low-energy electrons effectively. (author)

  20. Quantitative low-energy electron diffraction analysis of the GaN(000-1) (1×1) reconstruction

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Jiříček, Petr; Paskova, T.

    2012-01-01

    Roč. 606, 7-8 (2012), s. 740-743 ISSN 0039-6028 R&D Projects: GA ČR GPP204/10/P028 Institutional research plan: CEZ:AV0Z10100521 Keywords : gallium nitride * semiconductor surfaces * quantitative low-energy electron diffraction * LEED Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.838, year: 2012

  1. A research of possibility for negative muon production by a low energy electron beam accompanying ion beam

    International Nuclear Information System (INIS)

    Uramoto, Joshin.

    1993-12-01

    A low energy electron beam (≤ 2000 eV) is injected perpendicularly to a uniform magnetic field, together with a low energy positive ion beam. On this magnetic mass analysis (using the uniform magnetic field), a peak of secondary electron current to the beam collector (arranging as a mass analyzer of 90deg type), appears at an analyzing magnetic field which corresponds exactly to a relation of negative muon μ - (the mass m=207 m e and the charge q=e, where m e and e are mass and charge of electron). The ion beam is essential for the peak appearance, which is produced by decelerating electrically the electron beam in front of the entrance slit of the mass analyzer, and by introducing a neutral gas into the electron beam region and producing a plasma through the ionization. We consider that a very small amount of negative muons may be produced through local cyclotron motions of the injected beam electrons in the ion beam or by an interaction between the bunched beam electrons and beam ions. (author)

  2. Oxygen adsorption on Cu-9 at. %Al(111) studied by low energy electron diffraction and Auger electron spectroscopy

    Science.gov (United States)

    Yoshitake, Michiko; Bera, Santanu; Yamauchi, Yasuhiro; Song, Weijie

    2003-07-01

    Cu-based alloys have been used for electric cables for long time. In the field of microelectronics, Al had been used for electrical wiring. However, it became clear that electromigration occurs in Al that causes breaking of wires in minute wirings. Due to this problem, Cu wiring is used in most advanced microprocessors. Cu metal is more corrosive than Al and Cu-based alloys with a small amount of Al is expected to solve problems both on electromigration and corrosion. The initial stage of corrosion is oxygen adsorption. We studied surface segregation of Al on Cu-9% Al(111) and oxygen adsorption on the surface with/without Al segregation in ultrahigh vacuum by low energy electron diffraction (LEED) and Auger electron spectroscopy. It was found that Al segregates on the surface to form (√3×√3)R30° structure and the structure vanishes above 595 K to give (1×1) structure while Al still segregates. The specimen was exposed to oxygen at different temperatures. The amount of oxygen uptake was not structure dependent but temperature dependent. Below 595 K, only a small amount of oxygen adsorbed. Between 595 and 870 K, oxygen adsorbed surface showed amorphous LEED pattern. The specimen was annealed at 1070 K after oxygen exposure. When the specimen was exposed oxygen below 870 K, the oxygen Auger intensity decreased significantly by annealing and the annealed surface showed (√3×√3)R30° structure at room temperature. When the specimen was exposed to oxygen at 870 K, diffused spots developed newly in LEED pattern but the pattern disappeared after 1070 K annealing while oxygen Auger intensity remained almost constant. Exposing the specimen to oxygen at 995 K resulted in clear spots in the LEED pattern, which were attributed to the (7/√3×7√3)R30° structure.

  3. Influence of low energy N+ ions pre-treatment on damage effects of UV-B irradiation on M1 rice

    International Nuclear Information System (INIS)

    Zhao Shuaipeng; Huang Qunce; Chen Xueneng

    2011-01-01

    The seedlings of rice (xindao18) were exposed to UV-B (10.08 kJ/(m 2 ·d 1 )) irradiation following the pretreatment with three different implantation dosages of low-energy N + ions. Changes in the levels of the superoxide (POD), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), glutathione (GSH) and soluble sugar were measured. The result showed that the UV-B irradiation on the seedlings of rice pretreated with low-energy ions implantation could lead to increase activities in POD and SOD, and the maximum appeared on the dose of 2.0 x 10 17 ions/cm 2 . Meanwhile, it made the content of GSH increased, and caused the activity of CAT and the content of MDA to be decreased. But there was no obvious change in soluble sugar. It was suggested that the rice pretreated by low energy ion implantation could enhance the antioxidation capacity and defensive ability when irradiated by UV-B, and the antioxidation system could be induced earlier than carbohydrate system. Therefore,the biological effects of UV-B irradiation on rice pretreated by low energy ion implantation were quite obvious. (authors)

  4. A low energy electron microscopy study of the initial growth, structure and thermal stability of BDA-domains on Cu(001)

    NARCIS (Netherlands)

    Khokhar, F.S.; van Gastel, Raoul; Schwarz, Daniel; Schwarz, Daniel; Zandvliet, Henricus J.W.; Poelsema, Bene

    2011-01-01

    The growth of 4,4′-biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene

  5. The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Gonderman, S.; Bharadwaj, N.; Hassanein, A.

    2016-09-15

    We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He{sup +} ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C{sup +} ion impurities in He{sup +} ion irradiations. For introducing such tiny C{sup +} ion impurities, gas mixtures of He and CH{sub 4} have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He{sup +} ion (for Mo fuzz growth due to only He{sup +} ions) and 100% H{sup +} ion (for confirming the significance of tiny 0.04–2.0% H{sup +} ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 × 10{sup 24} ions m{sup −2}), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He{sup +} ion irradiation case. Enhancement of C{sup +} ion impurities in He{sup +} ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C{sup +} ion impurity concentrations. Additionally, no fuzz formation for 100% H{sup +} ion irradiation at all, were seen (apart from some tiny nano-structuring, in very limited regions). This indicates that there is no significant role of H{sup +} ions in Mo fuzz evolutions (at least for such tiny amount, 0.04–2.0% H{sup +} ions). The study is significant to understand the behavior of potential high-Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications. - Highlights: • Mo Fuzz evolutions due to low-energy high-flux 100% He{sup +} ion irradiation. • Sequential reduction in Mo fuzz evolutions with increasing C{sup +} ion impurities in He{sup +} ions. • Almost complete prevention of Mo

  6. Effects of a low-energy proton irradiation on n+/p-AlInGaP solar cells

    International Nuclear Information System (INIS)

    Lee, H.S.; Yamaguchi, M.; Ekins-Daukes, N.J.; Khan, A.; Takamoto, T.; Imaizumi, M.; Ohshima, T.; Itoh, H.

    2006-01-01

    For the first time, by deep-level transient spectroscopy, 30keV proton irradiation-induced defects in n + /p-AlInGaP solar cells have been observed. After the 30keV proton irradiation, new deep-level defects such as two majority-carrier (hole) traps HP1 (E V +0.98eV, N T =3.8x10 14 cm -3 ) and HP2, and two minority-carrier (electron) traps EP1 (E C -0.71eV, N T =2.0x10 15 cm -3 ) and EP2 have been observed in p-AlInGaP. The introduction rate of majority-carrier trap center (HP1) is 380cm -1 , which is lower than that (1500cm -1 ) in 100keV proton-irradiated p-InGaP. From the minority-carrier injection annealing for HP1 defect and carrier concentration in 30keV proton-irradiated p-AlInGaP, HP1 defect is likely to act as a recombination center as well as a compensator center

  7. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  8. Very low-energy conversion electron detection (VLECED) system at the isocele on-line isotope separator, Orsay

    International Nuclear Information System (INIS)

    Kilcher, P.; Sauvage, J.; Munsch, J.; Obert, J.; Caruette, A.; Ferro, A.; Boissier, G.; Fournet-Fayas, J.; Ducourtieux, M.; Landois, G.

    1988-01-01

    A system designed and installed at the on-line isotope separator ISOCELE II allows the high resolution detection of low-energy conversion electrons (down to 1 keV) emitted by mass separated radioactive sources: the use of a special tape transport permits both the slowing down of the incoming beam of radioactive ions up to a collection point and the acceleration of the electrons emitted by the collected sources brought to a flat magnetic spectrograph. Typical spectra so obtained are presented

  9. Performance, Defect Behavior and Carrier Enhancement in Low Energy, Proton Irradiated p(+)nn(+) InP Solar Cells

    Science.gov (United States)

    Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

    1994-01-01

    InP p(+)nn(+) cells, processed by MOCVD, were irradiated by 0.2 MeV protons and their performance and defect behavior observed to a maximum fluence of 10(exp 13)/sq cm. Their radiation induced degradation, over this fluence range, was considerably+less than observed for similarly irradiated, diffused junction n p InP cells. Significant degradation occurred in both the cell's emitter and base regions the least degradation occurring in the depletion region. A significant increase in series resistance occurs at the highest fluenc.e. Two majority carrier defect levels, E7 and E10, are observed by DLTS with activation energies at (E(sub C) - 0.39)eV and (E(sub C) - 0.74)eV respectively. The relative concentration of these defects differs considerably from that observed after 1 MeV electron irradiation. An increased carrier concentration in the cell's n-region was observed at the highest proton fluence, the change in carrier concentration being insignificant at the lower fluences. In agreement with previous results, for 1 and 1.5 MeV electron irradiated InP p(+)n junctions, the defect level E10 is attributed to a complex between zinc, diffused into the n-region from the zinc doped emitter, and a radiation induced defect. The latter is assumed to be either a phosphorus vacancy or interstitial. The increased, or enhanced carrier concentration is attributed to this complex acting as a donor.

  10. Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films

    National Research Council Canada - National Science Library

    Davis, R

    1999-01-01

    The homoepitaxial growth of GaN(0001) layers was studied in situ and in real time using the low-energy electron microscope and ex situ using atomic force microscopy and transmission electron microscopy...

  11. A variable electron beam and its irradiation effect on optical and ...

    Indian Academy of Sciences (India)

    A low energy electron accelerator has been constructed and tested. The electron beam can operate in low energy mode (100 eV to 10 keV) having a beam diameter of 8–10 mm. Thin films of CdS having thickness of 100 nm deposited on ITO-coated glass substrate by thermal evaporation method have been irradiated by ...

  12. A Low-Energy-Spread Rf Accelerator for a Far-Infrared Free-Electron Laser

    NARCIS (Netherlands)

    van der Geer, C. A. J.; Bakker, R. J.; van der Meer, A. F. G.; van Amersfoort, P. W.; Gillespie, W. A.; Saxon, G.; Poole, M. W.

    1993-01-01

    A high electron current and a small energy spread are essential for the operation of a free electron laser (FEL). In this paper we discuss the design and performance of the accelerator for FELIX, the free electron laser for infrared experiments. The system consists of a thermionic gun, a prebuncher,

  13. Electron beam dosimetry for a thin-layer absorber irradiated by 300-keV electrons

    International Nuclear Information System (INIS)

    Kijima, Toshiyuki; Nakase, Yoshiaki

    1993-01-01

    Depth-dose distributions in thin-layer absorbers were measured for 300-keV electrons from a scanning-type irradiation system, the electrons having penetrated through a Ti-window and an air gap. Irradiations of stacks of cellulose triacetate(CTA) film were carried out using either a conveyor (i.e. dynamic irradiation) or fixed (i.e. static) irradiation. The sample was irradiated using various angles of incidence of electrons, in order to examine the effect of obliqueness of electron incidence at low-energy representative of routine radiation curing of thin polymeric or resin layers. Dynamic irradiation gives broader and shallower depth-dose distributions than static irradiation. Greater obliqueness of incident electrons gives results that can be explained in terms of broader and shallower depth-dose distributions. The back-scattering of incident electrons by a metal(Sn) backing material enhances the absorbed dose in a polymeric layer and changes the overall distribution. It is suggested that any theoretical estimations of the absorbed dose in thin layers irradiated in electron beam curing must be accomplished and supported by experimental data such as that provided by this investigation. (Author)

  14. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Laurent, G.; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A.

    2003-01-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O 6+ + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O 4+ (1s 2 nln ' l ' ) populated after double electron-capture events

  15. Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

    Science.gov (United States)

    Adaniya, Hidehito; Cheung, Martin; Cassidy, Cathal; Yamashita, Masao; Shintake, Tsumoru

    2018-05-01

    A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Low-energy plasma-cathode electron gun with a perforated emission electrode

    Science.gov (United States)

    Burdovitsin, Victor; Kazakov, Andrey; Medovnik, Alexander; Oks, Efim; Tyunkov, Andrey

    2017-11-01

    We describe research of influence of the geometric parameters of perforated electrode on emission parameters of a plasma cathode electron gun generating continuous electron beams at gas pressure 5-6 Pa. It is shown, that the emission current increases with increasing the hole diameters and decreasing the thickness of the perforated emission electrode. Plasma-cathode gun with perforated electron can provide electron extraction with an efficiency of up to 72 %. It is shown, that the current-voltage characteristic of the electron gun with a perforated emission electrode differs from that of similar guns with fine mesh grid electrode. The plasma-cathode electron gun with perforated emission electrode is used for electron beam welding and sintering.

  17. Apparatus for irradiation with electron beam

    International Nuclear Information System (INIS)

    Uehara, K.; Ito, A.; Nishimune, K.; Fujita, K.

    1976-01-01

    An irradiation apparatus with high energy electrons is disclosed in which a wire shaped or linear object to be irradiated is moved back and forth many times under an electron window so as to irradiate it with an electron beam. According to one feature of the invention, an electron beam, which leaks through gaps between the objects to be irradiated or which penetrates the objects to be irradiated, is reversed by a magnetic field approximately perpendicular to the scanning face of the electron beam by means of a magnet which is disposed under the objects to be irradiated, and the reversed electron beam is thereby again applied to the objects to be irradiated. A high utilization rate of the electron beam is accomplished, and the objects can be thereby uniformly irradiated with the electron beam. 4 claims, 6 drawing figures

  18. Determination of low-energy ion-induced electron yields from thin carbon foils

    International Nuclear Information System (INIS)

    Allegrini, Frederic; Wimmer-Schweingruber, Robert F.; Wurz, Peter; Bochsler, Peter

    2003-01-01

    Ion beams crossing thin carbon foils can cause electron emission from the entrance and exit surface. Thin carbon foils are used in various types of time-of-flight (TOF) mass spectrometers to produce start pulses for TOF measurements. The yield of emitted electrons depends, among other parameters, on the energy of the incoming ion and its mass, and it has been experimentally determined for a few projectile elements. The electron emission yield is of great importance for deriving abundance ratios of elements and isotopes in space plasmas using TOF mass spectrometers. We have developed a detector for measuring ion-induced electron yields, and we have extended the electron yield measurements for oxygen to energies relevant for solar wind research. We also present first measurements of the carbon foil electron emission yield for argon and iron in the solar wind energy range

  19. Design aspects of an electrostatic electron cooler for low-energy RHIC operation

    International Nuclear Information System (INIS)

    Fedotov, A.; Ben-Zvi, I.; Brodowski, J.; Chang, X.Y.; Gassner, D.; Hoff, L.; Kayran, D.; Kewisch, J.; Oerter, B.; Pendzick, A.; Tepikian, S.; Thieberger, P.; Prost, L.; Shemyakin, A.

    2011-01-01

    Electron cooling was proposed to increase the luminosity of the Relativistic Heavy Ion Collider (RHIC) operation for heavy ion beam energies below 10 GeV/nucleon. The electron cooling system needed should be able to deliver an electron beam of adequate quality in a wide range of electron beam energies (0.9-5 MeV). An option of using an electrostatic accelerator to produce electrons for cooling heavy ions in RHIC was evaluated in detail. In this paper, we describe the requirements and options which were considered in the design of such a cooler for RHIC, as well as the associated challenges. The expected luminosity improvement and limitations with such an electron cooling system are also discussed.

  20. Analysis of low energy neutral hydrogen fluxes using an electron cyclotron resonance heated discharge

    International Nuclear Information System (INIS)

    Cain, B.L.

    1989-01-01

    This dissertation describes the design, construction, and proof-of-principle verification of a neutral hydrogen flux detection system, based on an ECRH discharge as the neutral flux ionizer. The significant features of the ionizer are its small size and simultaneous excitation of the ECRH mode using a 30 MHz RF driver and relatively small static magnetic fields. Demonstrated is the ability of the ECRH ionizer to ionize ∼ 900 eV neutral hydrogen fluxes with subsequent detection in a high resolution energy analyzer. A versatile calibration technique is applied to determine the ionizer efficiency, which additionally gives a variety of elastic scattering and charge exchange cross section results. Also described are the details of a new low energy beam-target interaction research facility, along with the basic techniques required to calibrate many of the system components. The facility has potential applications in areas such as fundamental cross section measurement, plasma diagnostics, beam-plasma interactions, and further beam-target research. 111 refs., 82 figs

  1. Flow direction variations of low energy ions as measured by the ion electron sensor (IES) flying on board of Rosetta

    Science.gov (United States)

    Szegö, Karoly; Nemeth, Zoltan; Foldy, Lajos; Burch, James L.; Goldstein, Raymond; Mandt, Kathleen; Mokashi, Prachet; Broiles, Tom

    2015-04-01

    The Ion Electron Sensor (IES) simultaneously measures ions and electrons with two separate electrostatic plasma analyzers in the energy range of 4 eV- 22 keV for ions. The field of view is 90ox360o, with angular resolution 5ox45o for ions, with a sector containing the solar wind being further segmented to 5o × 5o. IES has operated continuously since early 2014. In the ion data a low energy (energy ions. Here we analyze the arrival direction of this low energy component. The origin of these low energy ions is certainly the ionized component of the neutral gas emitted due to solar activity from comet 67P/Churiumov-Gerasimenko. The low energy component in general shows a 6h periodicity due to cometary rotation. The data show, however, that the arrival direction of the low energy ions is smeared both in azimuth and elevation, due possibly to the diverse mechanisms affecting these ions. One of these effects is the spacecraft potential (~-10V), which accelerates the ions towards the spacecraft omnidirectionally. To characterize the flow direction in azimuth-elevation, we have integrated over the lowest 8 energy channels using weighted energy: sum(counts * energy)/sum(counts); and considered only cases when the counts are above 30. When we apply higher cut for counts, the flow direction became more definite. For this analysis we use data files where the two neighbouring energy values and elevation values are collapsed; and the azimuthal resolution is 45o, that is the solar wind azimuthal segmentation is also collapsed. Here we use day 2014.09.11. as illustration. On that day a solar wind shock reached the spacecraft at about ~10 UT. After the shock transition the energy of the solar wind became higher, and after ~12 UT the flow direction of the solar wind fluctuated, sometimes by 35o. On this day Rosetta flew at about 29.3-29.6 km from the nucleus. In the azimuth-elevation plots summed over "weighted energy" (as defined above) we were able to identify two flow directions

  2. 2-D Low Energy Electron Beam Profile Measurement Based on Computer Tomography Algorithm with Multi-Wire Scanner

    CERN Document Server

    Yu, Nengjie; Li Qing Feng; Tang, Chuan-Xiang; Zheng, Shuxin

    2005-01-01

    A new method for low energy electron beam profile measurement is advanced, which presents a full 2-D beam profile distribution other than the traditional 2-D beam profile distribution given by 1-D vertical and horizontal beam profiles. The method is based on the CT (Computer Tomography) algorithm. Multi-sets of data about the 1-D beam profile projections are attained by rotating the multi-wire scanner. Then a 2-D beam profile is reconstructed from these projections with CT algorithm. The principle of this method is presented. The simulation and the experiment results are compared and analyzed in detail.

  3. Wave Optical Calculation of Probe Size in Low Energy Scanning Electron Microscope

    Czech Academy of Sciences Publication Activity Database

    Radlička, Tomáš

    2015-01-01

    Roč. 21, S4 (2015), s. 212-217 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : scanning electron microscope * optical calculation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  4. Monte Carlo simulation of energy deposition by low-energy electrons in molecular hydrogen

    Science.gov (United States)

    Heaps, M. G.; Furman, D. R.; Green, A. E. S.

    1975-01-01

    A set of detailed atomic cross sections has been used to obtain the spatial deposition of energy by 1-20-eV electrons in molecular hydrogen by a Monte Carlo simulation of the actual trajectories. The energy deposition curve (energy per distance traversed) is quite peaked in the forward direction about the entry point for electrons with energies above the threshold of the electronic states, but the peak decreases and broadens noticeably as the electron energy decreases below 10 eV (threshold for the lowest excitable electronic state of H2). The curve also assumes a very symmetrical shape for energies below 10 eV, indicating the increasing importance of elastic collisions in determining the shape of the curve, although not the mode of energy deposition.

  5. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

    2003-05-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

  6. First Detection of Low Energy Electron Neutrinos in Liquid Argon Time Projection Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Corey James [Yale U.

    2016-01-01

    Electron neutrino appearance is the signature channel to address the most pressing questions in neutrino oscillations physics, at both long and short baselines. This includes the search for CP violation in the neutrino sector, which the U.S. flagship neutrino experiment DUNE will address. In addition, the Short Baseline Neutrino Program at Fermilab (MicroBooNE, SBND, ICARUS-T600) searches for new physics, such as sterile neutrinos, through electron neutrino appearance. Liquid argon time projection chambers are the forefront of neutrino detection technology, and the detector of choice for both short and long baseline neutrino oscillation experiments. This work presents the first experimental observation and study of electron neutrinos in the 1-10 GeV range, the essential oscillation energy regime for the above experiments. The systematic uncertainties for an electron neutrino appearance search for the Fermilab Short Baseline Neutrino Program are carefully quantified, and the characterization of separation between electrons and high energy photons is examined.

  7. Measurements on the gas desorption yield of the oxygen-free copper irradiated with low-energy Xe10+ and O+

    Science.gov (United States)

    Dong, Z. Q.; Li, P.; Yang, J. C.; Yuan, Y. J.; Xie, W. J.; Zheng, W. H.; Liu, X. J.; Chang, J. J.; Luo, C.; Meng, J.; Wang, J. C.; Wang, Y. M.; Yin, Y.; Chai, Z.

    2017-10-01

    Heavy ion beam lost on the accelerator vacuum wall will release quantity of gas molecules and make the vacuum system deteriorate seriously. This phenomenon is called dynamic vacuum effect, observed at CERN, GSI and BNL, leading to the decrease of beam lifetime when increasing beam intensity. Heavy ion-induced gas desorption, which results in dynamic vacuum effect, becomes one of the most important problems for future accelerators proposed to operate with intermediate charge state beams. In order to investigate the mechanism of this effect and find the solution method for the IMP future project High Intensity heavy-ion Accelerator Facility (HIAF), which is designed to extract 1 × 1011 uranium particles with intermediate charge state per cycle, two dedicated experiment setups have been installed at the beam line of the CSR and the 320 kV HV platform respectively. Recently, experiment was performed at the 320 kV HV platform to study effective gas desorption with oxygen-free copper target irradiated with continuous Xe10+ beam and O+ beam in low energy regime. Gas desorption yield in this energy regime was calculated and the link between gas desorption and electronic energy loss in Cu target was proved. These results will be used to support simulations about dynamic vacuum effect and optimizations about efficiency of collimators to be installed in the HIAF main synchrotron BRing, and will also provide guidance for future gas desorption measurements in high energy regime.

  8. Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

    Energy Technology Data Exchange (ETDEWEB)

    Bourke, J.D.; Chantler, C.T., E-mail: chantler@unimelb.edu.au

    2014-10-15

    We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques.

  9. Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

    International Nuclear Information System (INIS)

    Bourke, J.D.; Chantler, C.T.

    2014-01-01

    We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques

  10. Doubly differential cross sections of low-energy electrons emitted in the ionization of molecular hydrogen by bare carbon ions

    International Nuclear Information System (INIS)

    Tribedi, L.C.; Richard, P.; Ling, D.; Wang, Y.D.; Lin, C.D.; Moshammer, R.; Kerby, G.W. III; Gealy, M.W.; Rudd, M.E.

    1996-01-01

    We have measured the double differential cross sections (DDCS) (d 2 σ/d var-epsilon ed Ω e ) of low-energy electron emission in the ionization of H 2 bombarded by bare carbon ions of energy 30 MeV. The energy and angular distributions of the electron DDCS have been obtained for 12 different emission angles and for electron energies varying between 0.1 and 300 eV. We have also deduced the single differential and total ionization cross section from the measured DDCS. The data have been compared with the predictions of first Born approximations and the CDW-EIS (continuum distorted wave endash eikonal initial state) model. The CDW-EIS model provides an excellent agreement with the data. copyright 1996 The American Physical Society

  11. Simple polynomial approximation to modified Bethe formula low-energy electron stopping powers data

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A., E-mail: ana.taborda@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 92262 Fontenay-aux-Roses (France); Desbrée, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 92262 Fontenay-aux-Roses (France); Reis, M.A. [C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km139.7, 2685-066 Bobadela LRS (Portugal)

    2015-08-01

    A recently published detailed and exhaustive paper on cross-sections for ionisation induced by keV electrons clearly shows that electron phenomena occurring in parallel with X-ray processes may have been dramatically overlooked for many years, mainly when low atomic number species are involved since, in these cases, the fluorescence coefficient is smaller than the Auger yield. An immediate problem is encountered while attempting to tackle the issue. Accounting for electron phenomena requires the knowledge of the stopping power of electrons within, at least, a reasonably small error. Still, the Bethe formula for stopping powers is known to not be valid for electron energies below 30 keV, and its use leads to values far off experimental ones. Recently, a few authors have addressed this problem and both detailed tables of electron stopping powers for various atomic species and attempts to simplify the calculations, have emerged. Nevertheless, its implementation in software routines to efficiently calculate keV electron effects in materials quickly becomes a bit cumbersome. Following a procedure already used to establish efficient methods to calculate ionisation cross-sections by protons and alpha particles, it became clear that a simple polynomial approximation could be set, which allows retrieving the electronic stopping powers with errors of less than 20% for energies above 500 eV and less than 50% for energies between 50 eV and 500 eV. In this work, we present this approximation which, based on just six parameters, allows to recover electron stopping power values that are less than 20% different from recently published experimentally validated tabulated data.

  12. Spatial distribution of fluorescent light emitted from neon and nitrogen excited by low energy electron beams

    International Nuclear Information System (INIS)

    Morozov, A.; Kruecken, R.; Ulrich, A.; Wieser, J.

    2006-01-01

    Side-view intensity profiles of fluorescent light were measured for neon and nitrogen excited with 12 keV electron beams at gas pressures from 250 to 1400 hPa. The intensity profiles were compared with theoretical profiles calculated using the CASINO program which performs Monte Carlo simulations of electron scattering. It was assumed that the spatial distribution of fluorescent intensity is directly proportional to the spatial distribution of energy loss by primary electrons. The comparison shows good correlation of experimental data and the results of numeric simulations

  13. Studying the molecular mechanisms of radiation damage : low-energy electron interactions with biomolecules and medically relevant molecules

    International Nuclear Information System (INIS)

    Tanzer, K.

    2015-01-01

    Since it was discovered in the year 2000 that secondary electrons with energies below 20 eV, which are the most abundant secondary species produced upon the interaction of ionizing radiation with biological tissue, can induce severe damages in the DNA such as single and double strand breaks, the interest for the study of the interaction of electrons with essential molecules of the human body has grown immensely. Double strand breaks can lead to cancer and are therefore a substantial threat to human health, however, the radiation research community is not sure how these strand breaks are formed upon interaction with ionizing radiation. The fact that even electrons with energies well below the ionization threshold can induce great damage in biological molecules via a resonant process called dissociative electron attachment (DEA), has even furthered the interest in these electron interactions, as it was shown to be a very efficient decomposition mechanism. A variety of studies, such as DEA studies to components of the DNA, for example, have been undertaken so far to shed more light on the role electrons play in the radiation damage of biomolecules. In this thesis two nucleobases, adenine and hypoxanthine, have been studied by observing their response towards low-energy electrons. It has been found that these nucleobases behave in a similar manner upon low-energy electron interaction, as do other nucleobases, that have been studied previously. The loss of hydrogen is suspected to act as a precursor for the decomposition of the DNA and the nucleobases can also undergo ring cleavage, which will induce substantial damage in the DNA. Furthermore, the search for improved and more efficient methods for the treatment of cancer is as important as ever, considering the ever-rising number of cancer deaths. Radiotherapy has proven to be one of the best treatments for tumors, but was found to be ineffective in hypoxic - oxygen deprived - tumors. Compounds called radiosensitizers

  14. Energy-Filtered Tunnel Transistor: A New Device Concept Toward Extremely-Low Energy Consumption Electronics

    Science.gov (United States)

    2015-12-17

    other provision of law , no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a...excellent agreement with experimental findings. The energy filtering has been applied to single-electron transport and clear Coulomb staircases and... Coulomb oscillations have been demonstrated at room temperature. A new architecture of energy-filtered cold electron transistors has been designed and

  15. The low-energy electron accelerator LEA for pilot scale operations

    International Nuclear Information System (INIS)

    Mehnert, R.; Klenert, P.

    1990-01-01

    An electron processor equipped with a linear cathode has been developed for use in pilot scale radiation processing. It can provide electron beam powers up to 6 kW at energies between 150 and 200 keV. The design of some components of the processor system and first results of its operation as part of a pilot unit for curing of furniture elements will be discussed. (author)

  16. Rate coefficients for low-energy electron dissociative attachment to molecular hydrogen

    International Nuclear Information System (INIS)

    Horacek, J.; Houfek, K.; Cizek, M.; Murakami, I.; Kato, T.

    2003-02-01

    Calculation of rate constants for dissociative electron attachment to molecular hydrogen is reported. The calculation is based on an improved nonlocal resonance model of Cizek, Horacek and Domcke which takes fully into account the nonlocality of the resonance dynamics and uses potentials with correct asymptotic forms. The rate constants are calculated for all quantum numbers v and J of the target molecules and for electron temperature in the range 0-30000 K. (author)

  17. Electron accelerator technology research in food irradiation

    International Nuclear Information System (INIS)

    Jin Jianqiao; Ye Mingyang; Zhang Yue; Yang Bin; Xu Tao; Kong Xiangshan

    2014-01-01

    Electronic accelerator was applied to instead of cobalt sources for food irradiation, to keep food quality and to improve the effect of the treatment. Appropriate accelerator parameters lead to optimal technique. The irradiation effect is associated with the relationship between uniformity and irradiating speed, the effect of cargo size on radiation penetration, as well as other factors that affect the irradiation effects. Industrialization of electron accelerator irradiation will be looked to the future. (authors)

  18. Monte Carlo calculation of scattered radiation from applicators in low energy clinical electron beams

    International Nuclear Information System (INIS)

    Jabbari, N.; Hashemi-Malayeri, B.; Farajollahi, A. R.; Kazemnejad, A.

    2007-01-01

    In radiotherapy with electron beams, scattered radiation from an electron applicator influences the dose distribution in the patient. The contribution of this radiation to the patient dose is significant, even in modern accelerators. In most of radiotherapy treatment planning systems, this component is not explicitly included. In addition, the scattered radiation produced by applicators varies based on the applicator design as well as the field size and distance from the applicators. The aim of this study was to calculate the amount of scattered dose contribution from applicators. We also tried to provide an extensive set of calculated data that could be used as input or benchmark data for advanced treatment planning systems that use Monte Carlo algorithms for dose distribution calculations. Electron beams produced by a NEPTUN 10PC medical linac were modeled using the BEAMnrc system. Central axis depth dose curves of the electron beams were measured and calculated, with and without the applicators in place, for different field sizes and energies. The scattered radiation from the applicators was determined by subtracting the central axis depth dose curves obtained without the applicators from that with the applicator. The results of this study indicated that the scattered radiation from the electron applicators of the NEPTUN 10PC is significant and cannot be neglected in advanced treatment planning systems. Furthermore, our results showed that the scattered radiation depends on the field size and decreases almost linearly with depth. (author)

  19. Observation of strong reflection of electron waves exiting a ballistic channel at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, Canute I.; Campbell, Jason P.; Ryan, Jason T.; Gundlach, David; Cheung, Kin. P., E-mail: Kin.Cheung@NIST.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Liu, Changze [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); Institute of Microelectronics, Peking University, Beijing 100871 (China); Southwick, Richard G. [National Institute of Standards and Technology, Gaithersburg, MD 20899-8120 (United States); IBM Research, Albany, NY 12205 (United States); Oates, Anthony S. [Taiwan Semiconductor Manufacturing Corporation, Hsinchu 30844, Taiwan (China); Huang, Ru [Institute of Microelectronics, Peking University, Beijing 100871 (China)

    2016-06-15

    Wave scattering by a potential step is a ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the potential step is encountered upon exiting the device. Experiments so far seem to support this even if it is not clear why. Here we report clear evidence of coherent reflection when electron wave exits the channel of a nanoscale transistor and when the electron energy is low. The observed behavior is well described by a simple rectangular potential barrier model which the Schrodinger’s equation can be solved exactly. We can explain why reflection is not observed in most situations but cannot be ignored in some important situations. Our experiment also represents a direct measurement of electron injection velocity - a critical quantity in nanoscale transistors that is widely considered not measurable.

  20. Construction of energy loss function for low-energy electrons in helium

    Energy Technology Data Exchange (ETDEWEB)

    Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

    1976-02-01

    The energy loss function for electrons in the energy range from 50 eV to 1 keV in helium gas has been constructed by considering separately the energy loss in overcoming the ionization threshold, the loss manifested as kinetic energy of secondary electrons and the loss in the discrete state excitations. This has been done by utilizing recent measurements of Opal et al. on the energy spectrum of secondary electrons and incorporating the experimental data on cross sections for twenty-four excited states. The present results of the energy loss function are in good agreement with the Bethe formula for energies above 500 eV. For lower energies, where the Bethe formula is not applicable, the present results should be particularly useful.

  1. Spectroscopic studies of organic-inorganic composite film cured by low energy electron beam

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Dahlan Mohd; Ibrahim Abdullah; Eda Yuhana Ariffin

    2009-01-01

    Liquid epoxidized natural rubber acrylate (LENRA) film was reinforced with silica particles formed in-situ via sol gel process. Combination of these two components produces organic-inorganic composites. Tetraethyl orthosilicate (TEOS) was used as precursor material for silica generation. Sol gel reactions was carried out at different concentrations of TEOS i.e. between 10 and 50 phr. The compounds that contain silica were crosslinked by electron beam. Structural properties studies were carried out by Fourier Transform Infrared Spectrometer (FTIR). It was found that miscibility between organic and inorganic components improved with the presence of silanol groups (Si-OH) and polar solvent i.e. THF, via hydrogen bonding formation between siloxane and LENRA. Morphology study by the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed in-situ generated silica particles were homogenous and well dispersed at any concentrations of TEOS. (author)

  2. Optical radiation emitted by a silver surface bombarded by low-energy electrons

    International Nuclear Information System (INIS)

    Miserey, F.; Lebon, P.; Septier, A.; Trehin, F.; Beaugrand, C.

    1975-01-01

    Thick silver targets are obtained on flat glass discs by evaporation in a UHV cell (p -10 torr) and their optical coefficients measured by ellipsometry. A field-emission electron gun bombards a limited region of the target, corresponding to the entry pupil of a light spectrometer. Radiation emitted in the domain 250-600nm is analyzed for both normal and parallel polarizations. Spectral distributions of photons are obtained by using a very sensitive counting device including a multi channel analyzer. First experimental results concerning optical radiation generated by 6keV electrons are reported and compared to Transition Radiation and Bremsstrahlung theoretical spectra [fr

  3. Electron spectra resulting from autoionization in low-energy Li+ + He collisions

    International Nuclear Information System (INIS)

    Yagishita, A.; Wakiya, K.; Takayanagi, T.; Suzuki, H.; Koike, F.

    1979-09-01

    Spectra of electrons ejected from doubly excited states of helium have been extensively measured at several observation angles fro impact with lithium ions at energies lower than 5 KeV. ''Molecular-autoionization'' spectra have been found at forward observation angles, and analyzed in terms of the Gerber-Niehaus theory with modification. The spectral shapes of atomic-autoionization peaks have been discussed in relation to both the Barker-Berry effect and the Doppler effect. Excitation cross sections of autoionizing states have been determined by a new method that uses simultaneous impact of ions and electrons. (author)

  4. Low-energy electron dose-point kernel simulations using new physics models implemented in Geant4-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Bordes, Julien, E-mail: julien.bordes@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France); Incerti, Sébastien, E-mail: incerti@cenbg.in2p3.fr [Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Lampe, Nathanael, E-mail: nathanael.lampe@gmail.com [Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Bardiès, Manuel, E-mail: manuel.bardies@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France); Bordage, Marie-Claude, E-mail: marie-claude.bordage@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France)

    2017-05-01

    When low-energy electrons, such as Auger electrons, interact with liquid water, they induce highly localized ionizing energy depositions over ranges comparable to cell diameters. Monte Carlo track structure (MCTS) codes are suitable tools for performing dosimetry at this level. One of the main MCTS codes, Geant4-DNA, is equipped with only two sets of cross section models for low-energy electron interactions in liquid water (“option 2” and its improved version, “option 4”). To provide Geant4-DNA users with new alternative physics models, a set of cross sections, extracted from CPA100 MCTS code, have been added to Geant4-DNA. This new version is hereafter referred to as “Geant4-DNA-CPA100”. In this study, “Geant4-DNA-CPA100” was used to calculate low-energy electron dose-point kernels (DPKs) between 1 keV and 200 keV. Such kernels represent the radial energy deposited by an isotropic point source, a parameter that is useful for dosimetry calculations in nuclear medicine. In order to assess the influence of different physics models on DPK calculations, DPKs were calculated using the existing Geant4-DNA models (“option 2” and “option 4”), newly integrated CPA100 models, and the PENELOPE Monte Carlo code used in step-by-step mode for monoenergetic electrons. Additionally, a comparison was performed of two sets of DPKs that were simulated with “Geant4-DNA-CPA100” – the first set using Geant4′s default settings, and the second using CPA100′s original code default settings. A maximum difference of 9.4% was found between the Geant4-DNA-CPA100 and PENELOPE DPKs. Between the two Geant4-DNA existing models, slight differences, between 1 keV and 10 keV were observed. It was highlighted that the DPKs simulated with the two Geant4-DNA’s existing models were always broader than those generated with “Geant4-DNA-CPA100”. The discrepancies observed between the DPKs generated using Geant4-DNA’s existing models and “Geant4-DNA-CPA100” were

  5. Electron--noble-gas spin-flip scattering at low energy

    International Nuclear Information System (INIS)

    Walker, T.G.; Bonin, K.; Happer, W.

    1987-01-01

    The spin-exchange rates and spin-relaxation rates for thermal electrons colliding with noble-gas atoms are calculated using the orthogonalized-plane-wave approximation and via partial-wave analysis. The two techniques give similar results and are in order-of-magnitude agreement with the experimental rate in Ar

  6. UKRmol: a low-energy electron- and positron-molecule scattering suite

    Science.gov (United States)

    Carr, J. M.; Galiatsatos, P. G.; Gorfinkiel, J. D.; Harvey, A. G.; Lysaght, M. A.; Madden, D.; Mašín, Z.; Plummer, M.; Tennyson, J.; Varambhia, H. N.

    2012-03-01

    We describe the UK computational implementation of the R-matrix method for the treatment of electron and positron scattering from molecules. Recent developments in the UKRmol suite are detailed together with the collision processes it is enabling us to treat.

  7. AREAL low energy electron beam applications in life and materials sciences

    Energy Technology Data Exchange (ETDEWEB)

    Tsakanov, V.M., E-mail: tsakanov@asls.candle.am [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Yerevan State University, 0025 Yerevan (Armenia); Aroutiounian, R.M. [Yerevan State University, 0025 Yerevan (Armenia); Amatuni, G.A. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Aloyan, L.R.; Aslanyan, L.G. [Yerevan State University, 0025 Yerevan (Armenia); Avagyan, V.Sh. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Babayan, N.S. [Yerevan State University, 0025 Yerevan (Armenia); Institute of Molecular Biology NAS, 0014 Yerevan (Armenia); Buniatyan, V.V. [State Engineering University of Armenia, 0009 Yerevan (Armenia); Dalyan, Y.B.; Davtyan, H.D. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Derdzyan, M.V. [Institute for Physical Research NAS, 0203 Ashtarak (Armenia); Grigoryan, B.A. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Grigoryan, N.E. [A.I. Alikhanyan National Science Laboratory (YerPhi), 0036 Yerevan (Armenia); Hakobyan, L.S. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Haroutyunian, S.G. [Yerevan State University, 0025 Yerevan (Armenia); Harutiunyan, V.V. [A.I. Alikhanyan National Science Laboratory (YerPhi), 0036 Yerevan (Armenia); Hovhannesyan, K.L. [Institute for Physical Research NAS, 0203 Ashtarak (Armenia); Khachatryan, V.G. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Martirosyan, N.W. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); State Engineering University of Armenia, 0009 Yerevan (Armenia); Melikyan, G.S. [State Engineering University of Armenia, 0009 Yerevan (Armenia); and others

    2016-09-01

    The AREAL laser-driven RF gun provides 2–5 MeV energy ultrashort electron pulses for experimental study in life and materials sciences. We report the first experimental results of the AREAL beam application in the study of molecular-genetic effects, silicon-dielectric structures, ferroelectric nanofilms, and single crystals for scintillators.

  8. First observation of low energy electron neutrinos in a liquid argon time projection chamber

    Energy Technology Data Exchange (ETDEWEB)

    Acciarri, R.; Adams, C.; Asaadi, J.; Baller, B.; Bolton, T.; Bromberg, C.; Cavanna, F.; Church, E.; Edmunds, D.; Ereditato, A.; Farooq, S.; Fitzpatrick, R. S.; Fleming, B.; Hackenburg, A.; Horton-Smith, G.; James, C.; Lang, K.; Luo, X.; Mehdiyev, R.; Page, B.; Palamara, O.; Rebel, B.; Schukraft, A.; Scanavini, G.; Soderberg, M.; Spitz, J.; Szelc, A. M.; Weber, M.; Yang, T.; Zeller, G. P.

    2017-04-06

    Liquid argon time projection chambers (LArTPCs) produce remarkable fidelity in the observation of neutrino interactions. The superior capabilities of such detectors to reconstruct the spatial and calorimetric information of neutrino events have made them the detectors of choice in a number of experiments, specifically those looking to observe electron neutrino ($\

  9. Low energy electron attachment to cyanamide (NH{sub 2}CN)

    Energy Technology Data Exchange (ETDEWEB)

    Tanzer, Katrin; Denifl, Stephan, E-mail: Andrzej.Pelc@poczta.umcs.lublin.pl, E-mail: Stephan.Denifl@uibk.ac.at [Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Pelc, Andrzej, E-mail: Andrzej.Pelc@poczta.umcs.lublin.pl, E-mail: Stephan.Denifl@uibk.ac.at [Mass Spectrometry Department, Institute of Physics, Marie Curie-Sklodowska University, Pl. M. C.-Sklodowskiej 1, 20-031 Lublin (Poland); Huber, Stefan E. [Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Lehrstuhl für Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany); Czupyt, Z. [Ion Microprobe Facility Micro-area Analysis Laboratory, Polish Geological Institute–National Research Institute, Rakowiecka 4, 00-975 Warszawa (Poland)

    2015-01-21

    Cyanamide (NH{sub 2}CN) is a molecule relevant for interstellar chemistry and the chemical evolution of life. In the present investigation, dissociative electron attachment to NH{sub 2}CN has been studied in a crossed electron–molecular beams experiment in the electron energy range from about 0 eV to 14 eV. The following anionic species were detected: NHCN{sup −}, NCN{sup −}, CN{sup −}, NH{sub 2}{sup −}, NH{sup −}, and CH{sub 2}{sup −}. The anion formation proceeds within two broad electron energy regions, one between about 0.5 and 4.5 eV and a second between 4.5 and 12 eV. A discussion of possible reaction channels for all measured negative ions is provided. The experimental results are compared with calculations of the thermochemical thresholds of the anions observed. For the dehydrogenated parent anion, we explain the deviation between the experimental appearance energy of the anion with the calculated corresponding reaction threshold by electron attachment to the isomeric form of NH{sub 2}CN—carbodiimide.

  10. Calculations on Electron Capture in Low Energy Ion-Molecule Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Stancil, P.C. [Oak Ridge National Lab., TN (United States); Zygelman, B. [W.M. Keck Lab. for Computational Physics, Univ. of Nevada, Las Vegas, NV (United States); Kirby, K. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

    1997-12-31

    Recent progress on the application of a quantal, molecular-orbital, close-coupling approach to the calculation of electron capture in collisions of multiply charged ions with molecules is discussed. Preliminary results for single electron capture by N{sup 2+} with H{sub 2} are presented. Electron capture by multiply charged ions colliding with H{sub 2} is an important process in laboratory and astrophysical plasmas. It provides a recombination mechanism for multiply charged ions in x-ray ionized astronomical environments which may have sparse electron and atomic hydrogen abundances. In the divertor region of a tokamak fusion device, charge exchange of impurity ions with H{sub 2} plays a role in the ionization balance and the production of radiative energy loss leading to cooling, X-ray and ultraviolet auroral emission from Jupiter is believed to be due to charge exchange of O and S ions with H{sub 2} in the Jovian atmosphere. Solar wind ions interacting with cometary molecules may have produced the x-rays observed from Comet Hyakutake. In order to model and understand the behavior of these environments, it is necessary to obtain total, electronic state-selective (ESS), and vibrational (or rotational) state-selective (VSS) capture cross sections for collision energies as low as 10 meV/amu to as high as 100 keV/amu in some instances. Fortunately, charge transfer with molecular targets has received considerable experimental attention. Numerous measurements have been made with flow tubes, ion traps, and ion beams. Flow tube and ion trap studies generally provide information on rate coefficients for temperatures between 800 K and 20,000 K. In this article, we report on the progress of our group in implementing a quantum-mechanical Molecular Orbital Close Coupling (MOCC) approach to the study of electron capture by multiply charged ions in collisions with molecules. We illustrate this with a preliminary investigation of Single Electron Capture (SEC) by N{sup 2+} with H

  11. An investigation of the reflection of low energy electrons from the surfaces of layered transition metal dichalcogenides

    International Nuclear Information System (INIS)

    Smith, A.E.; Mohamed, M.H.; Wohlenberg, T.; Johnson, E.; Chadderton, L.T.; Moeller, P.J.

    1980-01-01

    Experimental measurements, using the total current spectroscopy (TCS) technique, on the energy dependence of the reflection of low energy electrons from clean surfaces of layered transition metal dichalcogenides are reported for the molybdenum semiconductor compounds 2H-MoS 2 and 2H-MoSe 2 . A simple model calculation involving both elastic and inelastic scattering is presented and correspondence established with the experimental spectra. In this picture information on the electronic band structure of the materials can then be extracted from the single particle component of the inelastic scattering. The model is extended to show that a feature in the 2H-MoS 2 experimental spectrum may be attributed to the excitation of an intermediate plasmon. (Auth.)

  12. Significance of Space Charge and the Earth Magnetic Field on the Dispersive Characteristics of a Low Energy Electron Beam

    CERN Document Server

    Kishek, Rami A; Bernal, Santiago; Godlove, Terry; Haber, Irving; Quinn, Bryan; Reiser, Martin; Tobin, C; Walter, Mark

    2005-01-01

    The combination of energy spread and space charge provides a rich domain for interesting beam dynamics that are currently not well understood. The University of Maryland Electron Ring (UMER) [1] is a small scaled ring designed to probe the little-known regions of higher beam intensities using low-energy electrons. As such, design, commissioning and operation of UMER present many challenges, some quite novel. For example the UMER beam energy of 10 keV makes the beam very sensitive to the Earth magnetic field, which we can fortunately use to assist in bending the beam. This paper presents a systematic simulation study of the interaction of space charge and energy spread, with and without the earth magnetic field.

  13. An experimental investigation of the reflection of low energy electrons from surfaces of 2H-MoS2

    International Nuclear Information System (INIS)

    Komolov, S.A.; Chadderton, L.T.

    1978-01-01

    Experiments are described in which a new technique - total current spectroscopy (TCS) - has been used to investigate the energy dependence of the reflection of low energy electrons from clean surfaces of the naturally occuring mineral molybdenite (2H-MoS 2 ). A theory involving both elastic and inelastic scattering of electrons is applied to a band structure calculated for molybdenite by Mattheiss. With relatively few approximations the results of numerical calculations for a TCS spectrum from molybdenite agree surprisingly well with experiment. It is suggested that TCS will prove to be a convenient and sensitive tool for the probing of energy structures in other solid surfaces. For the transition metal dichalcogenide series it should be possible to observe systematic changes in TCS spectra associated with changes in band structure, and subsequently to predict details in the density of states distributions using iterative computer procedures. (Auth.)

  14. Interaction of low energy electrons with surface lattice vibrations. Final report

    International Nuclear Information System (INIS)

    Tong, S.Y.

    1984-01-01

    In carrying out the DOE contract, we have succeeded in constructing a new microscopic theory, with multiple scattering, for the inelastic scattering of electrons by surface vibrations. We have applied the theory to detailed studies of angle and energy variations of the inelastic cross-section for two important systems in surface physics: carbon monoxide molecules adsorbed on the (100) surface of a nickel crystal, and hydrogen atoms adsorbed on a reconstructed tungsten (100) surface. These calculations have outlined general trends that we expect to apply to a wide variety of systems. Also, we have discovered a series of new selection rules that apply to off-specular scattering. Particularly interesting are pseudo-selection rules which are not group theoretical in origin, but approximate statements that hold well when the electron scattering amplitude exhibits a slow energy variation. We have found and defined conditions for which these selection rules would hold and break down

  15. Low-energy magnetic dipole response in 56Fe from high-resolution electron scattering

    International Nuclear Information System (INIS)

    Fearick, R.W.; Hartung, G.; Langanke, K.; Martinez-Pinedo, G.; Neumann-Cosel, P. von; Richter, A.

    2003-01-01

    The 56 Fe(e, e') reaction has been studied for excitation energies up to about 8 MeV and momentum transfers q≅0.4-0.55 fm -1 at the Darmstadt electron linear accelerator (DALINAC) with kinematics emphasizing M1 transitions. Additional data have been taken for q≅0.8-1.7 fm -1 at the electron accelerator NIKHEF, Amsterdam. A PWBA analysis allows spin and parity determination of the excited states. For M1 excitations, transition strengths are derived with a DWBA analysis using shell-model form factors. The resulting B(M1) strength distribution is compared to shell-model calculations employing different effective interactions. The form factor of the prominent low-lying M1 transition at 3.449 MeV demonstrates its dominant orbital nature. It represents a major part of the scissors mode in 56 Fe

  16. Suppression of low-energy dissociative electron attachment in Fe(CO)5 upon clustering

    Czech Academy of Sciences Publication Activity Database

    Lengyel, Jozef; Papp, P.; Matejčík, Š.; Kočišek, Jaroslav; Fárník, Michal; Fedor, Juraj

    2017-01-01

    Roč. 8, č. 1 (2017), s. 2200-2207 ISSN 2190-4286 R&D Projects: GA ČR GA17-04844S; GA ČR(CZ) GA17-04068S; GA ČR GJ16-10995Y Grant - others:COST(XE) CM1301 Institutional support: RVO:61388955 Keywords : aggregation effects * FEBID * dissociative electron attachment Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.127, year: 2016

  17. Bibliography of low energy electron and photon cross section data (through December 1974). Final report

    International Nuclear Information System (INIS)

    Kieffer, L.J.

    1976-03-01

    A bibliography of original reports of measurements or calculations of electron, positron and photon cross sections and their ions is presented. A detailed index to the bibliography allows retrieval of cross section data for specific processes and atomic or molecular species. A comprehensive author index is included. The bibliography covers the period 1921 through calendar year 1974, but some references late in 1974 may not have been found and included. No references were found prior to 1921

  18. Bibliography of low energy electron and photon cross section data. Report for Jan 1975-Dec 1977

    International Nuclear Information System (INIS)

    Gallagher, J.W.; Rumble, J.R. Jr; Beaty, E.C.

    1979-06-01

    A bibliography of original reports of measurements or calculations of electron, positron, and photon cross sections for atoms, small molecules, and their ions is presented. A detailed index to the bibliography facilitates retrieval of cross section data for specific processes and associated atomic or molecular species. A comprehensive author index is included. The bibliography covers the calendar years 1975-1977. This work supplements a previous bibliography which covered the literature through 1974

  19. Limitations of the condensed history method for low-energy electrons

    International Nuclear Information System (INIS)

    Martin, W.R.; Ballinger, C.T.; Rathkopf, J.A.

    1991-01-01

    A systematic evaluation of the conventional, condensed history electron transport methodology has been performed through comparisons with more accurate single-scatter Monte Carlo calculations. These comparisons highlight the inaccuracies associated with the condensed history method and indicate its range of validity. The condensed history method is used in codes such as MCNP4, SANDYL, ETRAN, ITS, and EGS and requires a number of restrictive assumptions about the scattering characteristics to make tractable the analytical solution to the infinite-medium transport equation. Distributions describing electron characteristics after multiple collisions (multiscatter distributions) are constructed from such solutions and serve as the heart of the condensed history codes. A two-level approach is taken to quantify the errors inherent in condensed history. First, conventional condensed history multiscattering distributions in energy and angle are compared directly with analogous distributions generated with a single-scatter Monte Carlo code. This recently developed code directly simulates individual electron interactions. Second, the conventional distributions are replaced in the condensed history code by distributions constructed via a single-scatter Monte Carlo simulation

  20. Electron capture from H(2s) by H+ at low energies

    International Nuclear Information System (INIS)

    Blanco, S.A.; Falcon, C.A.; Piacentini, R.D.

    1986-01-01

    Total cross sections for resonant electron capture by protons from metastable H(2s) targets have been computed in a six-state molecular close-coupling formalism. Transitions between degenerate sublevels of the L shell of the target occurring at large internuclear distances have been taken into account in the impact parameter approximation. Cross sections are presented for impact velocities between 0.05 and 0.3 au. The results are compared with theoretical calculations for capture from H(2s) by Li 3+ , C 6+ and N 7+ . (author)

  1. Low-energy rate enhancement in recombination processes of electrons into bare uranium ions

    International Nuclear Information System (INIS)

    Wu Yong; Zeng Siliang; Duan Bin; Yan Jun; Wang Jianguo; Chinese Academy of Sciences, Lanzhou; Dong Chenzhong; Ma Xinwen

    2007-01-01

    Based on the Dirac-Fork-Slater method combined with the multichannel quantum defect theory, the recombination processes of electrons into bare uranium ions (U 92+ ) are investigated in the relative energy range close to zero, and the x-ray spectrum emitted in the direct radiative recombination and cascades processes are simulated. Compared with the recent measurement, it is found that the rate enhancement comes from the additional populations on high Rydberg states. These additional populations may be produced by other recombination mechanisms, such as the external electric-magnetic effects and the many-body correlation effects, which still remains an open problem. (authors)

  2. The energy broadening resulting from electron stripping process of a low energy Au- beam

    International Nuclear Information System (INIS)

    Taniike, Akira; Sasao, Mamiko; Hamada, Yasuji; Fujita, Junji; Wada, Motoi.

    1994-12-01

    Energy loss spectra of Au + ions produced from Au - ions by electron stripping in He, Ar, Kr and Xe have been measured in the impact energy range of 24-44 keV. The energy broadening of the Au + beam increases as the beam energy increases, and the spectrum shows a narrower energy width for heavy target atoms. The dependence of the spectrum width upon the beam energy and that upon the target mass are well described by the calculation based on the unified potential and semi-classical internal energy transfer model of Firsov's. (author)

  3. The momentum transfer cross section and transport coefficients for low energy electrons in mercury

    International Nuclear Information System (INIS)

    McEachran, R P; Elford, M T

    2003-01-01

    The momentum transfer cross section for electrons incident on mercury atoms has been determined from the solution of Dirac-Fock scattering equations which included both static and dynamic multipole polarization potentials as well as full anti-symmetrization to incorporate exchange effects. This cross section is in excellent agreement between 0.2 and 3.0 eV with the cross section derived from the most recent experimental measurements. The discrepancy below 0.2 eV has been investigated using two-term transport theory

  4. D-mu-A new concept in industrial low-energy electron dosimetry

    DEFF Research Database (Denmark)

    Helt-Hansen, Jakob; Miller, Arne; Sharpe, Peter

    2010-01-01

    , resulting in difficulties in providing traceable dose measurements using reference dosimeters. In order to overcome these problems a new concept is introduced of correcting all measured doses to the average dose in the first micrometer—Dμ. We have applied this concept to dose measurements with dosimeters...... of different thickness at two electron accelerators operating over a range of energies. The uncertainties of the dose measurements were evaluated, and it was shown that the dose in terms of Dμ was the same at each energy for all dosimeters within the measurement uncertainty. Using the concept of Dμ...

  5. The effectiveness of the microbiological radiation decontamination process of agricultural products with the use of low energy electron beam

    Science.gov (United States)

    Gryczka, Urszula; Migdał, Wojciech; Bułka, Sylwester

    2018-02-01

    The effectiveness of the radiation decontamination process was tested for electron beam of energy 200 keV and 300 keV. The energy of electrons was controlled by the measurements of its penetration ability in stack of B3 dosimetric film. In the presented work, the reduction of total aerobic bacteria count was observed, depending on time of irradiation for samples of dried black pepper, onion flakes and bay leaves. The results were compared with the effect observed for the process where high energy electron beam was used.

  6. Low-energy electron-helium scattering in a Nd–YAG laser field

    International Nuclear Information System (INIS)

    Ajana, I.; Makhoute, A.; Khalil, D.

    2014-01-01

    Highlights: • Laser assisted electron helium excitation is studied at low incident energies. • The inclusion of the second-order Born contributions is significant at low incident energies. • The target distortion induced by the laser field should be taken into account. • The effect of the second term of the Born series is reduced as the energy increases. - Abstract: We study the electron-impact excitation of atomic helium, in the presence of a linearly polarized Nd–YAG laser field, accompanied by the transfer of ℓ photons, for low collision energy of 25 eV and laser intensity of 5.3 × 10 11 W cm −2 . The second-order Born approximation has been used to calculate the differential cross sections. Detailed calculations of the scattering amplitudes are performed by using the Sturmian basis expansion. A detailed analysis is made of the excitation of the 1 1 S → 2 1 S and 1 1 S → 2 1 P transitions. We discuss the behavior and the variation of the cross sections corresponding to the excitation process for various geometrical configurations

  7. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons

    International Nuclear Information System (INIS)

    Almeida, Ivan Pedro Salati de

    1995-08-01

    The evaluation of absorbed dose in the case of external and internal contamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy 109 Cd conversion electrons, working with a 4 π proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin 109 Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  8. Low-Energy Nuclear Reactions Resulting as Picometer Interactions with Similarity to K-Shell Electron Capture

    Science.gov (United States)

    Hora, H.; Miley, G. H.; Li, X. Z.; Kelly, J. C.; Osman, F.

    2006-02-01

    Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons or deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockroft-Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the "life after death" heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of picometers with reaction probability times U of about megaseconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the picometer-megasecond reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas.

  9. Low-energy nuclear reactions resulting as parametric interactions with similarity to K-shell electron capture

    International Nuclear Information System (INIS)

    Hora, H.; Miley, G.H.; Li, X.Z.; Kelly, J.C.; Osman, F.

    2006-01-01

    Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons of deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockcroft Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the 'life after death' heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of pico-meters with reaction probability times U of about mega-seconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the pico-meter- mega-second reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas. (authors)

  10. Low energy electron capture in collisions of C3+ with He

    International Nuclear Information System (INIS)

    Wu, Y.; Qi, Y.Y.; Yan, J.; Wang, J.G.; Li, Y.; Buenker, R.J.; Kato, D.

    2009-06-01

    Charge transfer processes due to collisions of ground state C 3+ (1s 2 2s 2 S) ions with He atom are investigated using the quantum-mechanical molecular-orbital close-coupling (QMOCC) method for energies between 10 -4 eV/u and 10 3 eV/u. The ab initio adiabatic potential and radial coupling utilized in the QMOCC calculations are obtained from the multi-reference single- and double-excitation configuration interaction (MRD-CI) approach. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained and compared with the available experimental and theoretical data. Good agreement between the measured SEC cross sections and the present calculation is found, but the previous calculation of total rate coefficient using the Landau-Zener model is one or two orders of magnitude smaller than the present result. (author)

  11. A coincidence-type ion-electron converter detector for low-energy protons

    International Nuclear Information System (INIS)

    Benka, O.; Weinzierl, P.; Dobrozemsky, R.; Stratowa, C.

    1981-04-01

    A coincidence type ion-electron converter detector has been developed and used - together with an electrostatic energy-analyser - for precision measurements of the energy distribution of recoil protons from free-neutron decay. The most important aspect of the development was, besides keeping the background below 0,2 counts/sec in the presence of a certain radiation background, to achieve a high and energy-independent counting probability for protons with energies between 100 and 1000 eV. With an acceleration voltage of about 25 kV and Al-foils (20 to 35 ug/cmsup2) as converter, we obtained counting efficiences of 70 to 85 percent. The design and performance of the detector system, employing six foils with different sensitive areas, are described and discussed in detail. (author)

  12. Single-electron capture in low-energy Ar6+-He collisions

    International Nuclear Information System (INIS)

    Akguengoer, K.; Kamber, E.Y.; Ferguson, S.M.

    1997-01-01

    Double differential cross sections for state-selective single-electron capture processes in Ar 6+ -He collisions have been measured at laboratory energies between 75 and 900 eV and scattering angles between 0 and 8 . At the lowest energy, the zero-angle spectrum shows capture into Ar 5+ (4p) to be the most important channel. However, as the scattering angle is increased, a second peak appears at angles ≥2 and becomes more pronounced relative to the 4p capture channel. The energy spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model. Total and differential cross sections are also measured and compared with available measurements and calculations. (orig.)

  13. Properties of a new magnetic dipole mode discovered in low energy electron scattering

    International Nuclear Information System (INIS)

    Bohle, D.; Guhr, T.; Hartmann, U.; Hummel, K.D.; Kilgus, G.; Milkau, U.; Richter, A.

    1986-01-01

    In a large range of nuclei low lying J π =1 + states have been found that are excited predominantly by a new M1 mode. Four properties of the new mode will be discussed in detail. Firstly, from the excitation energy systematics observed the strength of the Majorana force of the interacting boson model (IBA) is deduced. Secondly, through the comparison of electron scattering and proton scattering experiments it is shown that the new mode is largely due to the orbital motion of protons with respect to neutrons. Thirdly, taking the nucleus 164 Dy as an example, g-factors and effective boson charges of the M1-, E2- and M3 IBA transition operators, respectively, are studied. The F-scalar magnetic octupol g-factor Ω S is derived for the first time. Finally, the distribution of M1 strength in 156 Gd will be discussed in the light of recent theoretical calculations. (orig.)

  14. Exploring reciprocity as a tool in low-energy electronic stopping

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, Valery [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Sigmund, Peter [Department of Physics and Chemistry, University of Southern Denmark, DK-5230 Odense M (Denmark)

    2011-05-01

    A computer code has been developed to explore reciprocity, i.e. the equivalence of electronic stopping cross sections for the ion-target pair A in B with that for B in A in the regime around and below the Bohr speed. With the aim of establishing reciprocity as a tool for identifying reliable experimental data and interpolating between them, we have studied stopping cross sections involving carbon, aluminium and gold either as projectile ions or as target materials. The case of carbon - where numerous data are available - is used to illustrate in detail various options to establish a body of credible data. Aluminium and gold serve to illustrate the case where these elements mostly are found as target materials in available data.

  15. Low-energy electron-induced dissociation in gas-phase nicotine, pyridine, and methyl-pyrrolidine

    Science.gov (United States)

    Ryszka, Michal; Alizadeh, Elahe; Li, Zhou; Ptasińska, Sylwia

    2017-09-01

    Dissociative electron attachment to nicotine, pyridine, and N-methyl-pyrrolidine was studied in the gas phase in order to assess their stability with respect to low-energy electron interactions. Anion yield curves for different products at electron energies ranging from zero to 15 eV were measured, and the molecular fragmentation pathways were proposed. Nicotine does not form a stable parent anion or a dehydrogenated anion, contrary to other biological systems. However, we have observed complex dissociation pathways involving fragmentation at the pyrrolidine side accompanied by isomerization mechanisms. Combining structure optimization and enthalpy calculations, performed with the Gaussian09 package, with the comparison with a deuterium-labeled N-methyl-d3-pyrrolidine allowed for the determination of the fragmentation pathways. In contrast to nicotine and N-methylpyrrolidine, the dominant pathway in dissociative electron attachment to pyridine is the loss of hydrogen, leading to the formation of an [M—H]- anion. The presented results provide important new information about the stability of nicotine and its constituent parts and contribute to a better understanding of the fragmentation mechanisms and their effects on the biological environment.

  16. Ab initio calculation of scattering length and cross sections at very low energies for electron-helium scattering

    International Nuclear Information System (INIS)

    Saha, H.P.

    1993-01-01

    The multiconfiguration Hartree-Fock method for continuum wave functions has been used to calculate the scattering length and phase shifts over extremely low energies ranging from 0 to 1 eV very accurately for electron-helium scattering. The scattering length is calculated very accurately with wave functions computed exactly at zero energy, resulting in an upper bound of 1.1784. The electron correlation and polarization of the target by the scattering electron, which are very important in these calculations, have been taken into account in an accurate ab initio manner through the configuration-interaction procedure by optimizing both bound and continuum orbitals simultaneously at each kinetic energy of the scattered electron. Detailed results for scattering length, differential, total, and momentum-transfer cross sections obtained from the phase shifts are presented. The present scattering length is found to be in excellent agreement with the experimental result of Andrick and Bitsch [J. Phys. B 8, 402 (1975)] and the theoretical result of O'Malley, Burke, and Berrington [J. Phys. B 12, 953 (1979)]. There is excellent agreement between the present total cross sections and the corresponding experimental measurements of Buckman and Lohmann [J. Phys. B 19, 2547 (1986)]. The present momentum-transfer cross sections also show remarkable agreement with the experimental results of Crompton, Elford, and Robertson [Aust. J. Phys. 23, 667 (1970)

  17. Progress in ETA-II magnetic field alignment using stretched wire and low energy electron beam techniques

    International Nuclear Information System (INIS)

    Griffith, L.V.; Deadrick, F.J.

    1991-01-01

    Flux line alignment of the solenoidal focus magnets used on the ETA-II linear induction accelerator is a key element leading to a reduction of beam corkscrew motion. Two techniques have been used on the ETA-II accelerator to measure and establish magnet alignment. A low energy electron beam has been used to directly map magnetic field lines, and recent work has utilized a pulsed stretched wire technique to measure magnet tilts and offsets with respect to a reference axis. This paper reports on the techniques used in the ETA-II accelerator alignment, and presents results from those measurements which show that accelerator is magnetically aligned to within ∼ ± 200 microns

  18. Atmospheric deterioration of clean surface of epitaxial (001)-YBaCuO films studied by low-energy electron diffraction

    International Nuclear Information System (INIS)

    Ohara, Tomoyuki; Sakuta, Ken; Kamishiro, Makio; Kobayashi, Takeshi

    1991-01-01

    The effects of gas exposure on the clean surface of the epitaxial YBaCuO thin films were closely investigated using the low-energy electron diffraction (LEED) method. The clean surface was obtained by in-vacuum annealing at 500degC. Once the clean surface was exposed to air, even at room temperature, the LEED spots disappeared or sometimes became faint. To ensure the degradation mechanism of the YBaCuO clean surface, the specimens were exposed to pure O 2 and N 2 gases separately and measured by LEED. As a result, it was found that O 2 is very safe but N 2 serves as a poisonous gas for the YBaCuO clean surface. (author)

  19. Determination of the specific resistance of individual freestanding ZnO nanowires with the low energy electron point source microscope

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Dirk Henning; Beyer, Andre; Voelkel, Berthold; Goelzhaeuser, Armin [Physik Supramolekularer Systeme, Universitaet Bielefeld (Germany); Schlenker, Eva; Bakin, Andrey; Waag, Andreas [Institut fuer Halbleitertechnik, Technische Universitaet Braunschweig (Germany)

    2008-07-01

    A low energy electron point source (LEEPS) microscope is used to determine the electrical conductivity of individual freestanding ZnO nanowires in UHV. The nanowires were contacted with a manipulation tip and I-V curves were taken at different wire lengths. From those, the specific resistance was calculated and separated from the contact resistance. By comparing the specific resistances of ZnO nanowires with diameters between 1100 and 48 nm, a large surface contribution for the thin nanowires was found. A geometric model for separation between surface and bulk contributions is given. The results of electrical transport measurements on vapor phase grown ZnO nanowires are discussed, as well as the size dependence of the wire resistance.

  20. Charge Exchange in Low-Energy H, D + C4+ Collisions with Full Account of Electron Translation

    Directory of Open Access Journals (Sweden)

    N. Vaeck

    2002-03-01

    Full Text Available We report the application of the quantum approach, which takes full account of electron translation at low collisional energies, to the charge exchange process H, D + C4+ → H+, D+ + C3+(3s; 3p; 3d. The partial and the total integral cross sections of the process are calculated in the energy range from 1 till 60 eV/amu. It is shown that the present results are independent from the upper integration limit for numerical solution of the coupled channel equations although nonadiabatic couplings remain nonzero up to infinity. The calculated partial and total cross sections are in agreement with the previous low-energy calculations and the available experimental data. It is shown that for low collisional energies the isotopic effect takes place. The observed effect is explained in terms of the nonadiabatic dynamics.

  1. Use of spectrophotometric readout method for free radical dosimetry in radiation processing including low energy electrons and bremsstrahlung

    International Nuclear Information System (INIS)

    Gupta, B.L.

    2000-01-01

    Our laboratory maintains standards for high doses in India. The glutamine powder dosimeter (spectrophotometric readout) is used for this purpose. Present studies show that 20 mg of unirradiated/irradiated glutamine dissolved in freshly prepared 10 ml of aerated aqueous acidic FX solution containing 2 x 10 -3 mol dm -3 ferrous ammonium sulphate and 10 -4 mol dm -3 xylenol orange in 0.033 mol dm -3 sulphuric acid is suitable for the dosimetry in the dose range of 0.1-100 kGy. Normally no corrections are required for the post-irradiation fading of the irradiated glutamine. The response of glutamine dosimeter is independent of irradiation temperature in the range of about 23-30 deg. C and at other temperatures, a correction is necessary. The dose intercomparison results for photon, electron and bremsstrahlung radiations show that glutamine can be used as a reference standard dosimeter. The use of flat polyethylene bags containing glutamine powder has proved very successful for electron dosimetry of wide energies. Several other amino acids like alanine, valine and threonine can also be used to cover wide range of doses using spectrophotometric readout method. (author)

  2. Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Elahe, E-mail: Elahe.Alizadeh@USherbrooke.ca [Groupe en science des radiations, Departement de medecine nucleaire et radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, J1H 5N4 (Canada); Sanche, Leon, E-mail: Leon.Sanche@USherbrooke.ca [Groupe en science des radiations, Departement de medecine nucleaire et radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, J1H 5N4 (Canada)

    2012-01-15

    Five-monolayer (5 ML) plasmid DNA films deposited on glass and tantalum substrates were exposed to Al K{sub {alpha}} X-rays of 1.5 keV under gaseous nitrous oxide (N{sub 2}O) at atmospheric pressure and temperature. Whereas the damage yields for DNA deposited on glass are due to soft X-rays, those arising from DNA on tantalum are due to both the interaction of low energy photoelectrons from the metal and X-rays. Then, the differences in the yields of damage on glass and tantalum substrates, essentially arises from interaction of essentially low-energy electrons (LEEs) with DNA molecules and the surrounding atmosphere. The G-values (i.e., the number of moles of product per Joule of energy absorbed) for DNA strand breaks induced by LEEs (G{sub LEE}) and the lower limit of G-values for soft X-ray photons (G{sub XL}) were calculated and the results compared to those from previous studies under atmospheric conditions and other ambient gases, such as N{sub 2} and O{sub 2}. Under N{sub 2}O, the G-values for loss of supercoiled DNA are 103{+-}15 nmol/J for X-rays, and 737{+-}110 nmol/J for LEEs. Compared to corresponding values in an O{sub 2} atmosphere, the effectiveness of X-rays to damage DNA in N{sub 2}O is less, but the G value for LEEs in N{sub 2}O is more than twice the corresponding value for an oxygenated environment. This result indicates a higher effectiveness for LEEs relative to N{sub 2} and O{sub 2} environments in causing SSB and DSB in an N{sub 2}O environment. Thus, the previously observed radiosensitization of cells by N{sub 2}O may not be only due to OH{sup {center_dot}} radicals but also to the reaction of LEE with N{sub 2}O molecules near DNA. The previous experiments with N{sub 2} and O{sub 2} and the present one demonstrate the possibility to investigate damage induced by LEEs to biomolecules under various types of surrounding atmospheres. - Highlights: > A completely different and new approach is applied to investigate the radiation chemistry of N

  3. Holography and coherent diffraction with low-energy electrons: A route towards structural biology at the single molecule level.

    Science.gov (United States)

    Latychevskaia, Tatiana; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

    2015-12-01

    The current state of the art in structural biology is led by NMR, X-ray crystallography and TEM investigations. These powerful tools however all rely on averaging over a large ensemble of molecules. Here, we present an alternative concept aiming at structural analysis at the single molecule level. We show that by combining electron holography and coherent diffraction imaging estimations concerning the phase of the scattered wave become needless as the phase information is extracted from the data directly and unambiguously. Performed with low-energy electrons the resolution of this lens-less microscope is just limited by the De Broglie wavelength of the electron wave and the numerical aperture, given by detector geometry. In imaging freestanding graphene, a resolution of 2Å has been achieved revealing the 660.000 unit cells of the graphene sheet from a single data set. Once applied to individual biomolecules the method shall ultimately allow for non-destructive imaging and imports the potential to distinguish between different conformations of proteins with atomic resolution. Copyright © 2015. Published by Elsevier B.V.

  4. Research of transportation efficiency of low-energy high- current electron beam in plasma channel in external magnetic field

    International Nuclear Information System (INIS)

    Vagin, E S; Grigoriev, V P

    2015-01-01

    Effective high current (5-20 kA) and low energy (tens of keV) electrons beam transportation is possible only with almost complete charging neutralization. It is also necessary to use quite high current neutralization for elimination beam self-pinching effect. The research is based on the self-consistent mathematical model that takes into account beam and plasma particles dynamic, current and charge neutralization of electron beam and examines the transportation of electron beam into a chamber with low-pressure plasma in magnetic field. A numerical study was conducted using particle in cell (PIC) method. The study was performed with various system parameters: rise time and magnitude of the beam current, gas pressure and plasma density and geometry of the system. Regularities of local virtual cathode field generated by the beam in the plasma channel, as well as ranges of parameters that let transportation beam with minimal losses, depending on the external magnetic field were determined through a series of numerical studies. In addition, the assessment of the impact of the plasma ion mobility during the transition period and during steady beam was performed. (paper)

  5. The effect of low-energy electrons on the response of ion chambers to ionizing photon beams

    Science.gov (United States)

    La Russa, Daniel J.

    Cavity ionization chambers are one of the most popular and widely used devices for quantifying ionizing photon beams. This popularity originates from the precision of these devices and the relative ease with which ionization measurements are converted to quantities of interest in therapeutic radiology or radiation protection, collectively referred to as radiation dosimetry. The formalisms used for these conversions, known as cavity theory, make several assumptions about the electron spectrum in the low-energy range resulting from the incident photon beam. These electrons often account for a significant fraction of the ion chamber response. An inadequate treatment of low-energy electrons can therefore significantly effect calculated quantities of interest. This thesis sets out to investigate the effect of low-energy electrons on (1) the use of Spencer-Attix cavity theory with 60Co beams; and (2) the standard temperature-pressure correction factor, P TP, used to relate the measured ionization to a set of reference temperature and pressure conditions for vented ion chambers. Problems with the PTP correction are shown to arise when used with kilovoltage x rays, where ionization measurements are due primarily to electrons that do not have enough energy to cross the cavity. A combination of measurements and Monte Carlo calculations using the EGSnrc Monte Carlo code demonstrate the breakdown of PTP in these situations when used with non-air-equivalent chambers. The extent of the breakdown is shown to depend on cavity size, energy of the incident photons, and the composition of the chamber. In the worst case, the standard P TP factor overcorrects the response of an aluminum chamber by ≈12% at an air density typical of Mexico City. The response of a more common graphite-walled chamber with similar dimensions at the same air density is undercorrected by ≈ 2%. The EGSnrc Monte Carlo code is also used to investigate Spencer-Attix cavity theory as it is used in the

  6. Experimental and theoretical study of very-low-energy inelastic processes in electron-molecule collisions. Progress report, March 20, 1982-March 20, 1983

    International Nuclear Information System (INIS)

    Golden, D.E.; Morrison, M.

    1983-01-01

    Objectives of this research are: to determine accurate integrated and differential cross sections for low energy electron-molecule elastic scattering, excitation and ionization; to develop, implement, and test new experimental and theoretical procedures for studying low energy collision processes; and to contribute to basic understanding of a fundamental problem in atomic collision physics, the interaction of a charged particle with a non-spherical target that is rich in structure

  7. Performance, defect behavior and carrier enhancement in low energy, proton irradiated p+nn+ InP solar cells

    Science.gov (United States)

    Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

    1994-01-01

    The highest AMO efficiency (19.1 percent) InP solar cell consisted of an n+pp+ structure epitaxially grown on a p+ InP substrate. However, the high cost and relative fragility of InP served as motivation for research efforts directed at heteroepitaxial growth of InP on more viable substrates. The highest AMO efficiency (13.7 percent) for this type of cell was achieved using a GaAs substrate. Considering only cost and fracture toughness, Si would be the preferred substrate. The fact that Si is a donor in InP introduces complexities which are necessary in order to avoid the formation of an efficiency limiting counterdiode. One method used to overcome this problem lies in employing an n+p+ tunnel junction in contact with the cell's p region. A simpler method consists of using an n+ substrate and processing the cell in the p+ nn+ configuration. This eliminates the need for a tunnel junction. Unfortunately, the p/n configuration has received relatively little attention the best cell with this geometry having achieved an efficiency of 17 percent. Irradiation of these homoepitaxial cells, with 1 Mev electrons, showed that they were slightly more radiation resistant than diffused junction n/p cells. Additional p/n InP cells have been processed by some activity aimed at diffusion. Currently, there has been some activity aimed at producing heteroepitaxial p+nn+ InP cells using n+ Ge substrates. Since, like Si, Ge is an n-dopant in InP, use of this configuration obviates the need for a tunnel junction. Obviously, before attempting to process heteroepitaxial cells, one must produce a reasonably good homoepitaxial cell. In the present case we focus our attention on homoepitaxially on an n+ Ge substrate.

  8. Combined quantum-mechanics/molecular-mechanics dynamics simulation of A-DNA double strands irradiated by ultra-low-energy carbon ions

    Energy Technology Data Exchange (ETDEWEB)

    Ngaojampa, C.; Nimmanpipug, P. [Computer Simulation and Modeling Laboratory (CSML), Department of Chemistry and Center for Innovation Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.t [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Anuntalabhochai, S. [Molecular Biology Laboratory, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Lee, V.S., E-mail: vannajan@gmail.co [Computer Simulation and Modeling Laboratory (CSML), Department of Chemistry and Center for Innovation Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2011-02-15

    In order to promote understanding of the fundamentals of ultra-low-energy ion interaction with DNA, molecular dynamics simulations using combined quantum-mechanics/molecular-mechanics of poly-AT and poly-GC A-DNA double strands irradiated by <200 eV carbon ions were performed to investigate the molecular implications of mutation bias. The simulations were focused on the responses of the DNA backbones and nitrogenous bases to irradiation. Analyses of the root mean square displacements of the backbones and non-hydrogen atoms of base rings of the simulated DNA structure after irradiation revealed a potential preference of DNA double strand separation, dependent on the irradiating energy. The results show that for the backbones, the large difference in the displacement between poly-GC and poly-AT in the initial time period could be the reason for the backbone breakage; for the nitrogenous base pairs, A-T is 30% more sensitive or vulnerable to ion irradiation than G-C, demonstrating a preferential, instead of random, effect of irradiation-induced mutation.

  9. Combined quantum-mechanics/molecular-mechanics dynamics simulation of A-DNA double strands irradiated by ultra-low-energy carbon ions

    International Nuclear Information System (INIS)

    Ngaojampa, C.; Nimmanpipug, P.; Yu, L.D.; Anuntalabhochai, S.; Lee, V.S.

    2011-01-01

    In order to promote understanding of the fundamentals of ultra-low-energy ion interaction with DNA, molecular dynamics simulations using combined quantum-mechanics/molecular-mechanics of poly-AT and poly-GC A-DNA double strands irradiated by <200 eV carbon ions were performed to investigate the molecular implications of mutation bias. The simulations were focused on the responses of the DNA backbones and nitrogenous bases to irradiation. Analyses of the root mean square displacements of the backbones and non-hydrogen atoms of base rings of the simulated DNA structure after irradiation revealed a potential preference of DNA double strand separation, dependent on the irradiating energy. The results show that for the backbones, the large difference in the displacement between poly-GC and poly-AT in the initial time period could be the reason for the backbone breakage; for the nitrogenous base pairs, A-T is 30% more sensitive or vulnerable to ion irradiation than G-C, demonstrating a preferential, instead of random, effect of irradiation-induced mutation.

  10. Low-energy nuclear reactions resulting as parametric interactions with similarity to K-shell electron capture

    Energy Technology Data Exchange (ETDEWEB)

    Hora, H. [University of New South Wales, Sydney 2052 (Australia); Miley, G.H. [Fusion Studies Laboratory, University of Illinois, Urbana, lL 61801 (United States); Li, X.Z. [Physics Department, Tsinghua University, Beijing 100084 (China); Kelly, J.C. [School of Physics, Sydney University, Sydney 2006 (Australia); Osman, F. [University of Western Sydney, Penrith-Soutti, NSW 1791 (Australia)

    2006-07-01

    Since the appeal by Brian Josephson at the meeting of the Nobel Laureates July 2004, it seems to be indicated to summarize the following serious, reproducible and confirmed observations on reactions of protons of deuterons incorporated in host metals such as palladium. Some reflections to Rutherford's discovery of nuclear physics, the Cockcroft Oliphant discovery of anomalous low-energy fusion reactions and the chemist Hahn's discovery of fission had to be included. Using gaseous atmosphere or discharges between palladium targets, rather significant results were seen e.g. from the 'life after death' heat production of such high values per host atom that only nuclear reactions can be involved. This supports the earlier evaluation of neutron generation in fully reversible experiments with gas discharges hinting that a reasonable screening effect - preferably in the swimming electron layer - may lead to reactions at nuclear distances d of pico-meters with reaction probability times U of about mega-seconds similar to the K-shell capture radioactivity. Further electrolytic experiments led to low-energy nuclear reactions (LENR) where the involvement of pollution could be excluded from the appearance of very seldom rare earth elements. A basically new theory for DD cross-sections is used to confirm the pico-meter- mega-second reactions of cold fusion. Other theoretical aspects are given from measured heavy element distributions similar to the standard abundance distribution, SAD, in the Universe with consequences on endothermic heavy nuclei generation, magic numbers and to quark-gluon plasmas. (authors)

  11. American College of Radiology-American Brachytherapy Society practice parameter for electronically generated low-energy radiation sources.

    Science.gov (United States)

    Devlin, Phillip M; Gaspar, Laurie E; Buzurovic, Ivan; Demanes, D Jeffrey; Kasper, Michael E; Nag, Subir; Ouhib, Zoubir; Petit, Joshua H; Rosenthal, Seth A; Small, William; Wallner, Paul E; Hartford, Alan C

    This collaborative practice parameter technical standard has been created between the American College of Radiology and American Brachytherapy Society to guide the usage of electronically generated low energy radiation sources (ELSs). It refers to the use of electronic X-ray sources with peak voltages up to 120 kVp to deliver therapeutic radiation therapy. The parameter provides a guideline for utilizing ELS, including patient selection and consent, treatment planning, and delivery processes. The parameter reviews the published clinical data with regard to ELS results in skin, breast, and other cancers. This technical standard recommends appropriate qualifications of the involved personnel. The parameter reviews the technical issues relating to equipment specifications as well as patient and personnel safety. Regarding suggestions for educational programs with regard to this parameter,it is suggested that the training level for clinicians be equivalent to that for other radiation therapies. It also suggests that ELS must be done using the same standards of quality and safety as those in place for other forms of radiation therapy. Copyright © 2017 American Brachytherapy Society and American College of Radiology. Published by Elsevier Inc. All rights reserved.

  12. FPGA-based upgrade of the read-out electronics for the low energy polarimeter at the cooler synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Hempelmann, Nils [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Collaboration: JEDI-Collaboration

    2015-07-01

    The Cooler Synchrotron (COSY) is a storage ring used for experiments with polarized proton and deuteron beams. The low energy polarimeter is used to determine the vector and tensor polarization of the beam before injection at kinetic energies up to 45 MeV for protons and 75 MeV for deuterons. The polarimeter uses scintillators to measure the energy of both outgoing particles of a scattering reaction and the time between their detection. The present read-out electronics consists of analog NIM modules and is limited in terms of time resolution and the capability for online data analysis. The read-out electronics will be replaced with a a new system based on analog pulse sampling and an FPGA chip for logic operations. The new system will be able to measure the time at which particles arrive to a precision better than 50 ps, facilitating better background reduction using coincidence measurement. In addition to measuring the beam polarization, the system will be used to precisely determine the vector and tensor analyzing powers for deuteron scattering off carbon at a kinetic energy of 75 MeV.

  13. Modulation transfer function and detective quantum efficiency of electron bombarded charge coupled device detector for low energy electrons

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav

    2005-01-01

    Roč. 76, č. 9 (2005), 093704:1-6 ISSN 0034-6748 R&D Projects: GA ČR(CZ) GA202/03/1575 Keywords : electron bombarded CCD * modulation transfer function * detective quantum efficiency Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.235, year: 2005

  14. Excitation of the 4.3-μm bands of CO2 by low-energy electrons

    International Nuclear Information System (INIS)

    Bulos, R.R.; Phelps, A.V.

    1976-01-01

    Rate coefficients for the excitation of the 4.3-μm bands of CO 2 by low-energy electrons in CO 2 have been measured using a drift-tube technique. The CO 2 density [(1.5 to 7) x 10 17 molecules/cm 3 ] was chosen to maximize the radiation reaching the detector. Line-by-line transmission calculations were used to take into account the absorption of 4.3-μm radiation. A small fraction of the approximately 10 -8 W of the 4.3-μm radiation produced by the approximately 10 -7 -A electron current was incident on an InSb photovoltaic detector. The detector calibration and absorption calculations were checked by measuring the readily calculated excitation coefficients for vibrational excitation of N 2 containing a small concentration of CO 2 . For pure CO 2 the number of molecules capable of emitting 4.3-μm radiation produced per cm of electron drift and per CO 2 molecule varied from 10 -17 cm -2 at E/N = 6 x 10 -17 V cm 2 to 5.4 x 10 -16 cm -2 at E/N = 4 x 10 -16 V cm 2 . Here E is the electric field and N is total gas density. The excitation coefficients at lower E/N are much larger than estimated previously. A set of vibrational excitation cross sections is obtained for CO 2 which is consistent with the excitation coefficient data and with most of the published electron-beam data

  15. Usability of a soft-electron (low-energy electron) machine for disinfestation of grains contaminated with insect pests

    International Nuclear Information System (INIS)

    Imamura, Taro; Miyanoshita, Akihiro; Todoriki, Setsuko; Hayashi, Toru

    2004-01-01

    Efficacy of soft-electron treatment for disinfestations of grains was investigated by treating pre-infested brown rice and adzuki bean with a commercial-scale soft-electron machine (soft-electron processor). Soft-electrons at 150 kV efficiently disinfested brown rice grains pre-infested with maize weevil (Stiophilus zeamais Motchulsky) and Indian meal moth (Plodia interpunctella (Huebner)) and adzuki beans with adzuki bean weevil (Callosobruchus chinensis (Linne)), although small numbers of the internal feeders such as C. chinensis in adzuki bean and S. zeamais in brown rice survived. The results indicate that the commercial-scale soft-electron machine can disinfest grains and beans, especially those contaminated with external feeders

  16. Usability of a soft-electron (low-energy electron) machine for disinfestation of grains contaminated with insect pests

    Science.gov (United States)

    Imamura, Taro; Miyanoshita, Akihiro; Todoriki, Setsuko; Hayashi, Toru

    2004-09-01

    Efficacy of soft-electron treatment for disinfestations of grains was investigated by treating pre-infested brown rice and adzuki bean with a commercial-scale soft-electron machine (soft-electron processor). Soft-electrons at 150 kV efficiently disinfested brown rice grains pre-infested with maize weevil ( Stiophilus zeamais Motchulsky) and Indian meal moth ( Plodia interpunctella (Hübner)) and adzuki beans with adzuki bean weevil ( Callosobruchus chinensis (Linne)), although small numbers of the internal feeders such as C. chinensis in adzuki bean and S. zeamais in brown rice survived. The results indicate that the commercial-scale soft-electron machine can disinfest grains and beans, especially those contaminated with external feeders.

  17. New Insights into the Mechanism Underlying the Synergistic Action of Ionizing Radiation With Platinum Chemotherapeutic Drugs: The Role of Low-Energy Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rezaee, Mohammad, E-mail: Mohammad.Rezaee@USherbrooke.ca; Hunting, Darel John; Sanche, Léon

    2013-11-15

    Purpose: To investigate the efficiencies of platinum chemotherapeutic drugs (Pt-drugs) in the sensitization of DNA to the direct effects of ionizing radiation and to determine the role of low-energy electrons (LEEs) in this process. Methods and Materials: Complexes of supercoiled plasmid DNA covalently bound to either cisplatin, carboplatin, or oxaliplatin were prepared in different molar ratios. Solid films of DNA and DNA modified by Pt-drugs were irradiated with either 10-KeV or 10-eV electrons. Damages to DNA were quantified by gel electrophoresis, and the yields for damage formation were obtained from exposure–response curves. Results: The presence of an average of 2 Pt-drug–DNA adducts (Pt-adducts) in 3199-bp plasmid DNA increases the probability of a double-strand break by factors of 3.1, 2.5, and 2.4 for carboplatin, cisplatin, and oxaliplatin, respectively. Electrons with energies of 10 eV and 10 KeV interact with Pt-adducts to preferentially enhance the formation of cluster lesions. The maximum increase in radiosensitivity per Pt-adduct is found at ratios up to 3.1 × 10{sup −4} Pt-adducts per nucleotide, which is equivalent to an average of 2 adducts per plasmid. Carboplatin and oxaliplatin show higher efficiencies than cisplatin in the radiosensitization of DNA. Because carboplatin and cisplatin give rise to identical reactive species that attach to DNA, carboplatin must be considered as a better radiosensitizer for equal numbers of Pt-adducts. Conclusion: Platinum chemotherapeutic drugs preferentially enhance the formation of cluster damage to DNA induced by the direct effect of ionizing radiation, and LEEs are the main species responsible for such an enhancement via the formation of electron resonances.

  18. New Insights into the Mechanism Underlying the Synergistic Action of Ionizing Radiation With Platinum Chemotherapeutic Drugs: The Role of Low-Energy Electrons

    International Nuclear Information System (INIS)

    Rezaee, Mohammad; Hunting, Darel John; Sanche, Léon

    2013-01-01

    Purpose: To investigate the efficiencies of platinum chemotherapeutic drugs (Pt-drugs) in the sensitization of DNA to the direct effects of ionizing radiation and to determine the role of low-energy electrons (LEEs) in this process. Methods and Materials: Complexes of supercoiled plasmid DNA covalently bound to either cisplatin, carboplatin, or oxaliplatin were prepared in different molar ratios. Solid films of DNA and DNA modified by Pt-drugs were irradiated with either 10-KeV or 10-eV electrons. Damages to DNA were quantified by gel electrophoresis, and the yields for damage formation were obtained from exposure–response curves. Results: The presence of an average of 2 Pt-drug–DNA adducts (Pt-adducts) in 3199-bp plasmid DNA increases the probability of a double-strand break by factors of 3.1, 2.5, and 2.4 for carboplatin, cisplatin, and oxaliplatin, respectively. Electrons with energies of 10 eV and 10 KeV interact with Pt-adducts to preferentially enhance the formation of cluster lesions. The maximum increase in radiosensitivity per Pt-adduct is found at ratios up to 3.1 × 10 −4 Pt-adducts per nucleotide, which is equivalent to an average of 2 adducts per plasmid. Carboplatin and oxaliplatin show higher efficiencies than cisplatin in the radiosensitization of DNA. Because carboplatin and cisplatin give rise to identical reactive species that attach to DNA, carboplatin must be considered as a better radiosensitizer for equal numbers of Pt-adducts. Conclusion: Platinum chemotherapeutic drugs preferentially enhance the formation of cluster damage to DNA induced by the direct effect of ionizing radiation, and LEEs are the main species responsible for such an enhancement via the formation of electron resonances

  19. Dependence of electron inelastic mean free paths on electron energy and materials at low energy region, 1

    International Nuclear Information System (INIS)

    Tanuma, Shigeo; Powell, C.J.; Penn, D.R.

    1990-01-01

    We have proposed a general formula of electron inelastic mean free path (IMFP) to describe the calculated IMFPs over the 50-2000 eV energy range based on the Inokuti's modified Bethe formula for the inelastic scattering cross section. The IMFPs for 50-2000 eV electrons in 27 elements were calculated using Penn's algorithm. The IMFP dependence on electron energy in the range 50-200 eV varies considerably from material to material. These variations are associated with substantial differences in the electron energy-loss functions amongst the material. We also found that the modified Bethe formula by Inokuti could be fitted to the calculated IMFPs in the range 50-2000 eV within 3% relative error. (author)

  20. Models for the transport of low energy electrons in water and the yield of hydrated electrons at early times

    International Nuclear Information System (INIS)

    Brenner, D.J.; Miller, J.H.; Ritchie, R.H.; Bichsel, H.

    1985-01-01

    An insulator model with four experimental energy bands was used to fit the optical properties of liquid water and to extend these data to non-zero momentum transfer. Inelastic mean free paths derived from this dielectric response function provided the basic information necessary to degrade high energy electrons to the subexcitation energy domain. Two approaches for the transport of subexcitation electrons were investigated. (i) Gas phase cross sections were used to degrade subexcitation electrons to thermal energy and the thermalization lengths were scaled to unit density. (ii) Thermalization lengths were estimated by age-diffusion theory with a stopping power deduced from the data on liquid water and transport cross sections derived from elastic scattering in water vapor. Theoretical ranges were compared to recent experimental results. A stochastic model was used to calculate the rapid diffusion and reaction of hydrated electrons with other radiolysis products. The sensitivity of the calculated yields to the model assumptions and comparison with experimental data are discussed

  1. Dose distributions in electron irradiated plastic tubing

    International Nuclear Information System (INIS)

    Miller, A.; Pederson, W.B.

    1981-01-01

    Plastic tubes have been crosslinked by irradiation at a 10 MeV linear electron accelerator and at a 400 keV DC electron accelerator at different irradiation geometries. The diameter of the different tubes was 20, 33 and 110 millimeters. Dose distributions have been measured with thin radiochromic dye films, indicating that in all cases irradiation from two sides is a necessary and sufficient condition for obtaining a satisfactory dose distribution. (author)

  2. Cleavage of thymine N3-H bonds by low-energy electrons attached to base π* orbitals

    International Nuclear Information System (INIS)

    Theodore, Magali; Sobczyk, Monika; Simons, Jack

    2006-01-01

    In this work, we extend our earlier studies on single strand break (SSB) formation in DNA to consider the possibility of cleaving a thymine N 3 -H bond to generate a nitrogen-centered anion and a hydrogen radical which might proceed to induce further bond cleavages. In earlier studies, we considered SSBs induced by low-energy electrons that attach to DNA bases' π* orbitals or to phosphate P=O π* orbitals to cleave sugar-phosphate C-O bonds or base-sugar N 1 -C bonds. We also studied the effects of base π-stacking on the rates of such bond cleavages. To date, our results suggest that sugar-phosphate C-O bonds have the lowest barriers to cleavage, that attachment of electrons with energies below 2 eV most likely occurs at the base π* orbitals, that electrons with energy above 2 eV can also attach to phosphate P=O π* orbitals, and that base π stacking has a modest but slowing effect on the rates of SSB formation. However, we had not yet examined the possibility that base N 3 -H bonds could rupture subsequent to base π* orbital capture. In the present work, the latter possibility is considered and it is found that the barrier to cleavage of the N 3 -H bond in thymine is considerably higher than for cleaving sugar-phosphate C-O bonds, so our prediction that SSB formation is dominated by C-O bond cleavage remains intact

  3. Effect of Ge nanocluster assembly self-organization at pulsed irradiation by low-energy ions during heteroepitaxy on Si

    CERN Document Server

    Dvurechenskij, A V; Smagina, Z V

    2001-01-01

    Using the method of scanning microscopy one studied experimentally size distribution of Ge clusters formed in course of experiments of two types at Ge heteroepitaxy on Si(111): regular process of molecular-beam epitaxy (MBE); pulse irradiation by approx = 200 eV energy Ge ions. The experiments were conducted at 350 deg C temperature. Pulse irradiation by an ion beam during heteroepitaxy was detected to result in reduction of the average size of Ge clusters, in compacting of their density and in reduction of mean square deviation from the average value in contrast to similar values in experiments devoted to regular MBE

  4. FPGA-based upgrade of the read-out electronics for the low energy polarimeter at COSY/Juelich

    Energy Technology Data Exchange (ETDEWEB)

    Hempelmann, Nils [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Collaboration: JEDI-Collaboration

    2016-07-01

    The Cooler Synchrotron (COSY) is a facility for cooled polarized beams at the Forschungszentrum in Juelich. The Low Energy Polarimeter (LEP) is the polarimeter in the injection beam line of COSY. The beam polarization is measured using scattering off carbon and polyethylene (CH2) targets. The outgoing particles are detected using twelve plastic scintillators installed in groups of three to the left, to the right, above, and below the beam. The LEP is the routine tool for beam set-up, but its performance was limited by the old read-out electronics consisting of analog NIM modules. A new system using analog pulse sampling and an FPGA chip for signal processing was installed and tested. The ejectile particles were identified by relative time of flight measurement using a signal from the RF amplifier of the cyclotron used for acceleration as a reference. The new system is able to measure the time at which a particle arrives to an accuracy in the order of 50 ps. The presentation includes a review of available systems and a report about measurements in May and December 2015.

  5. Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring-High Energy Ring at the Positron-Electron Project

    International Nuclear Information System (INIS)

    Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.

    2007-01-01

    A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored

  6. 1D chain formation by coadsorption of Pb and Bi on Cu(001): Determination using low energy electron diffraction

    Science.gov (United States)

    Kabiruzzaman, Md; Ahmed, Rezwan; Nakagawa, Takeshi; Mizuno, Seigi

    2017-10-01

    Coadsorption of two heavy metals, Pb and Bi, on Cu(001) at room temperature has been studied using low energy electron diffraction (LEED). c(4 × 4), c(2 × 2), and c(9√{ 2}×√{ 2}) phases are obtained at different coverages; here, we have determined the best-fit structure of c(4 × 4) phase. This structure can be described as a 1D substitutional chain arrangement of Pb and Bi atoms between the Cu rows along the [110] direction. The unit cell in the two-dimensional (2D) surface consists of one Bi atom, two Pb atoms, and four Cu atoms with one vacancy at the center. The optimal structure parameters demonstrate that Bi atoms are located at fourfold-hollow sites and that Pb atoms are laterally displaced by 0.78 Å from the fourfold-hollow site toward the vacancy. The reasons for the formation of the c(4 × 4) structure upon deposition of Pb and Bi on Cu(001) are discussed in comparison with a similar structure formed by the individual adsorption of Pb on the same substrate.

  7. A low energy electron microscopy study of the initial growth, structure, and thermal stability of 4,4'-biphenyldicarboxylic acid domains on Cu(001)

    International Nuclear Information System (INIS)

    Khokhar, Fawad S.; Gastel, Raoul van; Schwarz, Daniel; Zandvliet, Harold J. W.; Poelsema, Bene

    2011-01-01

    The growth of 4,4 ' -biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene rings of adsorbed BDA are twisted along the molecular axis. Unconventional growth of the domains, followed by a second nucleation stage, is observed at room temperature. This unanticipated feature is attributed to the accumulation of stress in the islands. Ostwald ripening in the films and the decay of BDA domains at 448 K exhibits features that are consistent with diffusion limited behavior.

  8. A low energy electron microscopy study of the initial growth, structure, and thermal stability of 4,4{sup '}-biphenyldicarboxylic acid domains on Cu(001)

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Fawad S.; Gastel, Raoul van; Schwarz, Daniel; Zandvliet, Harold J. W.; Poelsema, Bene [Physics of Interfaces and Nanomaterials, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, NL-7500AE Enschede (Netherlands)

    2011-09-28

    The growth of 4,4{sup '}-biphenyldicarboxylic acid (BDA) on Cu(001) has been studied using low energy electron microscopy and selective area low energy electron diffraction. The emergence of large islands and hydrogen bonding to perpendicularly oriented, adjacent molecules is confirmed. The two benzene rings of adsorbed BDA are twisted along the molecular axis. Unconventional growth of the domains, followed by a second nucleation stage, is observed at room temperature. This unanticipated feature is attributed to the accumulation of stress in the islands. Ostwald ripening in the films and the decay of BDA domains at 448 K exhibits features that are consistent with diffusion limited behavior.

  9. A study on irradiation damage of solid 5'-dTMP implanted by low energy N+ ion beam

    International Nuclear Information System (INIS)

    Shao Chunlin; Yu Zengliang

    1995-01-01

    The yields of inorganic phosphate and base released from 5'-dTMP irradiated by 30 keV N + ion beam were investigated. The fluence effects of these yields and the influence with 0.1 mol/L NaOH treatment on them were presented. It was shown that the alkali treatment would not only increase the yield of inorganic phosphate, but also damage and then split base released from the irradiated 5'-dTMP. When the irradiated samples were treated with 0.1 mol/L NaOH immediately, the yield of inorganic phosphate was increased by a factor of 1.7 and the concentration of base decreased to half of that in the sample's water solution. Furthermore, the yield of inorganic phosphate would increase by a factor of 2.8 after 40 min of alkali treatment. Irradiation effects of ion beam were mainly direct ones and had a higher value of G(P i ), greater than 0.44 molecule/100 eV

  10. Research into releasing inorganic phosphate and base from 5'-dTMP irradiated by a low energy ion beam

    International Nuclear Information System (INIS)

    Shao Chunlin; Yu Zengliang

    1994-01-01

    Research into radiation damage of nucleotide is an important area in radiation biology. In this paper, the yield of inorganic phosphate and base released from 5'-dTMP irradiated by a 30 keV N + ion beam was investigated in several aspects. The effect of particle fluence on yield and the influence of treatment with 0.1 N NaOH was deduced. By analysis, it is known that the alkali treatment not only increases the yield of inorganic phosphate, but also damages and splits the base released from irradiated 5'-dTMP. When the irradiated samples are treated by 0.1 N NaOH immediately, the yield of inorganic phosphate is increased by a factor of 1.7 and the concentration of base decreased to half of the original value. But the yield of inorganic phosphate could be increased by a factor of 2.8 after 40 min of alkali treatment. On the other hand, when 5'dTMP was irradiated by the ion beam, the G(Pi) obtained was above 0.44, higher than with γ-radiation. (Author)

  11. Tailoring Si(100) substrate surfaces for GaP growth by Ga deposition: A low-energy electron microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Rienäcker, Michael; Borkenhagen, Benjamin, E-mail: b.borkenhagen@pe.tu-clausthal.de; Lilienkamp, Gerhard; Daum, Winfried [TU Clausthal, Institut für Energieforschung und Physikalische Technologien, Leibnizstraße 4, D-38678 Clausthal-Zellerfeld (Germany)

    2015-08-07

    For GaP-on-Si(100) heteroepitaxy, currently considered as a model system for monolithic integration of III–V semiconductors on Si(100), the surface steps of Si(100) have a major impact on the quality of the GaP film. Monoatomic steps cause antiphase domains in GaP with detrimental electronic properties. A viable route is to grow the III–V epilayer on single-domain Si(100) with biatomic steps, but preferably not at the expense of reduced terrace widths introduced by miscut substrates. We have performed in situ investigations of the influence of Ga deposition on the kinetics of surface steps and terraces of Si(100) at substrate temperatures above 600 °C by low-energy electron microscopy. Starting from nearly equally distributed T{sub A} and T{sub B} terraces of a two-domain Si(100) surface, submonolayer deposition of Ga results in a transformation into a surface dominated by T{sub A} terraces and biatomic D{sub A} steps. This transformation is reversible, and Si(100) with monoatomic steps is recovered upon termination of the Ga flux. Under conditions of higher coverages (but still below 0.25 monolayer), we observe restructuring into a surface with T{sub B} dominance, similar to the findings of Hara et al. [J. Appl. Phys. 98, 083515 (2005)]. The occurrence and mutual transformations of surface structures with different terrace and step structures in a narrow range of temperatures and Ga deposition rates is discussed.

  12. A Preliminary Study of the Application of a Model Animal-Caenorhabidity elegans' Exposure to a Low-Energy Ion Irradiation System

    International Nuclear Information System (INIS)

    Liu Xuelan; Cai Kezhou; Feng Huiyun; Xu An; Yuan Hang; Yu Zengliang

    2007-01-01

    Because of the lack of suitable animal models adapted to high vacuum stress in the low-energy ion implantation system, the bio-effects ion irradiation with an energy less than 50 keV on multi-cellular animal individuals have never been investigated so far. The nematode Caenorhabditis elegans has proved to be an excellent animal model used for the study of a broad spectrum of biological issues. The purpose of this work was to investigate the viability of this animal under ion irradiation. We studied the protection effects of glycerol and trehalose on the enhancement of nematodes' ability to bear the vacuum stress. The results showed that the survival of the nematodes was enhanced remarkably under long and slow desiccation, even without glycerol and trehalose. 15% glycerol showed a better anti-vacuum stress effect on the nematodes than trehalose did under short-time desiccation. Low-temperature pre-treatment or post-treatment of the samples had no obvious effect on the survival scored after argon ion irradiation. Moreover, little effect was induced by 15% glycerol- and vacuum-exposure on germ cell apoptosis, compared to the untreated control sample. It issuggested that such treatment would provide relatively low background for genotoxic evaluations with ion irradiation

  13. Interaction of low-energy electrons and positrons with condensed matter: Stopping powers and inelastic mean free paths from optical data

    International Nuclear Information System (INIS)

    Ashley, J.C.

    1989-01-01

    An ''optical-data model'' is described for evaluating energy loss per unit pathlength and inelastic mean free path for low-energy electrons and positrons (approx lt 10 keV) from optical data on the medium of interest. Exchange between the incident electron and electrons in the medium is included. Results from the optical-data model are compared with previous theoretical calculations. 15 refs., 6 figs., 2 tabs

  14. Plastic coating on paper by electron beam irradiation

    International Nuclear Information System (INIS)

    Ametani, Kazuo; Tsuchiya, Mitsuaki; Sawai, Takeshi

    1984-01-01

    It has been known long since that the resin system of unsaturated polyester and vinylmonomer mixture cures by irradiation. Ford of USA for the first time industrialized the radiation curing reaction of resins for the coating of automobile parts. Thereafter, accompanying the development and technical advance of the low energy electron beam irradiation apparatus which is suitable to surface treatment such as coating and easy to handle and the development of resins, the electron beam curing method has become to be utilized for coating hardboard and wooden doors, coating automobile tire rims, adhering printing papers and others. The electron beam curing method has advantage such as energy conservation, resource saving and little pollution because solvent is not used, high production rate and small floor space. In glossing industry, for the purpose of developing the techniques to apply electron beam curing method to glazed paper production, the selection of the composition of resins suitable to glazed papers, the irradiating condition and the properties of cured films were examined. The films withstanding bending can be obtained at low dose with urethane group, ester group or the combination of monomers. (Kako, I.)

  15. Studies on watermelon somatic cell mutant of resistance to fusaric acid (FA) by low energy Ar+ ion beam irradiation

    International Nuclear Information System (INIS)

    Wang Haobo; Gu Yunhong; Cheng Guowang; Yu Zengliang

    2003-01-01

    Three kinds of watermelon seeds irradiated by Ar + ion beam (25 keV, 6.24 x 10 16 ions/cm 2 ) were inoculated in MS medium with 15 mg/L FA. Cotyledons from the sterile seedling as explants were inoculated in MS +BA 2.0 mg/L + FA 15 mg/L. And the adventitious shoots of resistance to FA were cultured in MS + NAA 0.2 mg/L + FA 15 mg/L. The results showed that both the irradiation of Ar + and FA affected the germination rate and seedling of watermelon line 3-27 and YH-5, and the joint effect of Ar + and FA showed an enhanced restraint. The adventitious shoot and rootage induction rate from the seeds irradiated by Ar + were respectively bigger than the unirradiated seeds in 3-27 and YH-5. The increasing ranges were different between two watermelon lines and between the shoot and rootage induction rates

  16. Low-energy neutron measurements in an iron calorimeter structure irradiated by 200 GeV/c hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Russ, J S [Carnegie-Mellon University, Pittsburgh, PA (United States); Stevenson, G R; Fasso, A; Nielsen, M C [CERN, Geneva (Switzerland); Furetta, C; Rancoita, P G; Vismara, I [INFN, Milan (Italy)

    1989-04-21

    Of serious concern in the design of detectors for the new high-luminosity hadron-hadron colliders are the radiation damage effects on silicon and other detectors of low-energy neutrons produced by spallation evaporation or fission processes. Because of the lack of experimental information on the number of neutrons with energies between 0.1 and 10 MeV in the cascades originating from high-energy hadrons, an experiment was carried out using activation detector techniques to measure the neutron fluence in a cascade initiated by 200 GeV hadrons in acalorimeter-like iron structure. It was found that at the maximum of the cascade one produces approximately 3 neutrons per GeV of incident energy: some 70% of these are of energies between 0.1 and 5 MeV, the remainder are fairly uniformly distributed in energy between 5 and several hundred MeV. The number of albedo neutrons leaving the front face of the calorimeter structure was about 0.3 neutrons per GeV of incident energy with in energy distribution similar to those at cascade maximum These data confirm that neutron-induced damage will he of concern in the design of detectors for the new colliders and that further measurements and calculations are necessary for a correct assessment of this damage. (author)

  17. Green coffee decontamination by electron beam irradiation

    International Nuclear Information System (INIS)

    Nemtanu, Monica R.; Brasoveanu, Mirela; Grecu, Maria Nicoleta; Minea, R.

    2005-01-01

    Microbiological load of green coffee is a real problem considering that it is extremely sensitive to contamination. Irradiation is a decontamination method for a lot of foodstuffs, being a feasible, very effective and environment friendly one. Beans and ground green coffee were irradiated with electron beams up to 40 kGy. Microbial load, rheological behavior, electron paramagnetic resonance (EPR) and visible spectroscopy were carried out. The results show that electron beam irradiation of green coffee could decontaminate it without severe changes in its properties

  18. Current state and prospects of industrial application of electron beam irradiation

    International Nuclear Information System (INIS)

    Washio, Masakazu

    2000-01-01

    This paper reviewed the low energy, medium energy, and high energy accelerators used for the industrial application of electron beams. Next, it described the absorption of electron beam energy, distribution of the absorbed dose of electron beams in a substance, and the basis of electron beam reaction. Furthermore, as the industrial application examples of electron beams, it briefly described about the reforming and curing of polymers, irradiation effect of inorganic material (characteristic control of semiconductors), and sterilization. Regarding curing, as examples using mainly low energy electron beams (300 keV or below), this paper briefly explained the manufacture of thermosensitive recording materials, electron beam cured silicone for release papers, tunnel metal interior finishing board, high gloss - high smooth paper. Finally, it looked at latest trends and prospects of electron beam generators. (A.O.)

  19. Structural changes induced by electron irradiation

    International Nuclear Information System (INIS)

    Koike, J.; Pedraza, D.F.

    1993-01-01

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300 kV electrons. Transmission electron microscopy and electron energy loss spectroscopy were employed to study the structural changes produced by irradiation. The occurrence of a continuous ring intensity in the selected area diffraction (SAD) pattern obtained on a specimen irradiated with the electron beam parallel to the c-crystallographic axis indicated that microstructural changes had occurred. However, from the SAD pattern obtained for the specimens tilted relative to the irradiation direction, it was found that up to a fluence of 1.1x10 27 e/m 2 graphite remained crystalline. An SAD pattern of a specimen irradiated with the electron beam perpendicular to the c-axis confirmed the persistence of crystalline order. High resolution electron microscopy showed that ordering along the c-axis direction remained. A density reduction of 8.9% due to irradiation was determined from the plasmon frequency shift. A qualitative model is proposed to explain these observations. A new determination of the threshold displacement energy, Ed, of carbon atoms in graphite was done by examining the appearance of a continuous ring in the SAD pattern at various electron energies. A value of 30 eV was obtained whether the incident electron beam was parallel or perpendicular to the c-axis, demonstrating that Ed is independent of the displacement direction

  20. Electronic energy states of HfSe/sub 2/ and NbSe/sub 2/ by low energy electron loss spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Ito, T; Iwami, M; Hiraki, A [Osaka Univ., Suita (Japan). Faculty of Engineering

    1981-06-01

    Low energy electron loss spectroscopy (ELS) study was performed on 1T-HfSe/sub 2/ (group IVB metal compound) and 2H-NbSe/sub 2/ (group VB metal compound) by using incident electron energies of 30-250 eV. From the loss data in the second derivative form, maxima in density-of-states in the conduction band of the compounds were deduced through the information on the filled core states by X-ray photoelectron spectroscopy. The conduction band of the transition-metal dichalcogenides could be divided into two parts. The results are discussed in relation to the previous work on WS/sub 2/ (group VIB metal compound), and also to proposals based on band calculations and experimental studies on the transition-metal dichalcogenides with constituent metals of group IVB, VB and VIB.

  1. Electron microscopy of boron carbide before and after electron irradiation

    International Nuclear Information System (INIS)

    Stoto, T.; Zuppiroli, L.; Beauvy, M.; Athanassiadis, T.

    1984-06-01

    The microstructure of boron carbide has been studied by electron microscopy and related to the composition of the material. After electron irradiations in an usual transmission electron microscope and in a high voltage electron microscope at different temperatures and fluxes no change of these microstructures have been observed but a sputtering of the surface of the samples, which has been studied quantitatively [fr

  2. Electron spin resonance identification of irradiated fruits

    International Nuclear Information System (INIS)

    Raffi, J.J.; Agnel, J.-P.L.

    1989-01-01

    The electron spin resonance spectrum of achenes, pips, stalks and stones from irradiated fruits (stawberry, raspberry, red currant, bilberry, apple, pear, fig, french prune, kiwi, water-melon and cherry) always displays, just after γ-treatment, a weak triplet (a H ∼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, raspberries, red currants or bilberries irradiated in order to improve their storage time. (author)

  3. INFLUENCE OF LOW-ENERGY AR-SPUTTERING ON THE ELECTRONIC-PROPERTIES OF INAS-BASED QUANTUM-WELL STRUCTURES

    NARCIS (Netherlands)

    Magnee, P.H.C.; den Hartog, S.G.; Wees, B.J.van; Klapwijk, T.M; van de Graaf, W.; Borghs, G.

    1995-01-01

    The influence of low energy (80-500 eV) Ar-ion milling cleaning techniques on InAs based quantum well structures is investigated. It is found that both etching with a Kaufmann source and sputter-etching with a rf-plasma enhances the electron density and reduces the mobility. An anneal at 180 degrees

  4. High energy electron irradiation of flowable materials

    International Nuclear Information System (INIS)

    Offermann, B.P.

    1975-01-01

    In order to efficiently irradiate a flowable material with high energy electrons, a hollow body is disposed in a container for the material and the material is caused to flow in the form of a thin layer across a surface of the body from or to the interior of the container while the material flowing across the body surface is irradiated. (U.S.)

  5. Investigation on the correlation between energy deposition and clustered DNA damage induced by low-energy electrons.

    Science.gov (United States)

    Liu, Wei; Tan, Zhenyu; Zhang, Liming; Champion, Christophe

    2018-05-01

    This study presents the correlation between energy deposition and clustered DNA damage, based on a Monte Carlo simulation of the spectrum of direct DNA damage induced by low-energy electrons including the dissociative electron attachment. Clustered DNA damage is classified as simple and complex in terms of the combination of single-strand breaks (SSBs) or double-strand breaks (DSBs) and adjacent base damage (BD). The results show that the energy depositions associated with about 90% of total clustered DNA damage are below 150 eV. The simple clustered DNA damage, which is constituted of the combination of SSBs and adjacent BD, is dominant, accounting for 90% of all clustered DNA damage, and the spectra of the energy depositions correlating with them are similar for different primary energies. One type of simple clustered DNA damage is the combination of a SSB and 1-5 BD, which is denoted as SSB + BD. The average contribution of SSB + BD to total simple clustered DNA damage reaches up to about 84% for the considered primary energies. In all forms of SSB + BD, the SSB + BD including only one base damage is dominant (above 80%). In addition, for the considered primary energies, there is no obvious difference between the average energy depositions for a fixed complexity of SSB + BD determined by the number of base damage, but average energy depositions increase with the complexity of SSB + BD. In the complex clustered DNA damage constituted by the combination of DSBs and BD around them, a relatively simple type is a DSB combining adjacent BD, marked as DSB + BD, and it is of substantial contribution (on average up to about 82%). The spectrum of DSB + BD is given mainly by the DSB in combination with different numbers of base damage, from 1 to 5. For the considered primary energies, the DSB combined with only one base damage contributes about 83% of total DSB + BD, and the average energy deposition is about 106 eV. However, the

  6. CoSi2 growth on Si(001) by reactive deposition epitaxy: Effects of high-flux, low-energy ion irradiation

    International Nuclear Information System (INIS)

    Lim, C. W.; Greene, J. E.; Petrov, I.

    2006-01-01

    CoSi 2 layers, CoSi 2 (parallel sign)(001) Si and [100] CoSi 2 (parallel sign)[100] Si , contain fourfold symmetric (111) twinned domains oriented such that (221) CoSi 2 (parallel sign)(001) Si and CoSi 2 (parallel sign)[110] Si . We demonstrate that high-flux low-energy (E Ar + =9.6 eV) Ar + ion irradiation during deposition dramatically increases the area fraction f u of untwinned regions from 0.17 in films grown under standard magnetically balanced conditions in which the ratio J Ar + /J Co of the incident Ar + to Co fluxes is 1.4 to 0.72 with J Ar + /J Co =13.3. TEM analyses show that the early stages of RDE CoSi 2 (001) film growth proceed via the Volmer-Weber mode with independent nucleation of both untwinned and twinned islands. Increasing J Ar + /J Co results in larger values of both the number density and area of untwinned with respect to twinned islands. The intense Ar + ion bombardment creates additional low-energy adsorption sites that favor the nucleation of untwinned islands while collisionally enhancing Co surface mobilities which, in turn, increases the probability of itinerant Co adatoms reaching these sites

  7. Dosimetry study for electron beam irradiation in radiation processing

    International Nuclear Information System (INIS)

    Sunaga, Hiromi; Haruyama, Yasuyuki; Takizawa, Haruki; Kojima, Takuji; Yotsumoto, Keiichi

    1995-01-01

    For certain critical applications such as medical device sterilization and food irradiation, accurate calibration of electron energy and absorbed dose is required to assure the quality of irradiated products. To meet this requirement, TRCRE, JAERI has carried out research and development on high dose radiation dosimetry for electron beams in the energy range used in radiation processing (0.15 - 3.0 MeV). JAERI has developed a simultaneous electron beam energy and dosimeter calibration system that consist of a total absorption calorimeter, an electron current density meter, and a stacked thin-film dosimeter set. For low energy electrons, where it is important to measure the depth-dose profile in materials with high depth resolution, we studied the feasibility of a method using Gafchromic film dosimeters. This film, which has an 8-μm thick sensitive layer, is combined with a stepped array of absorber films of the same thickness to produce a high-resolution depth-dose profile on the Gafchromic film. The depth-dose profile obtained in this manner has about five times greater resolution than conventional radiochromic film dosimetry. (author)

  8. Complete-active-space second-order perturbation theory (CASPT2//CASSCF) study of the dissociative electron attachment in canonical DNA nucleobases caused by low-energy electrons (0-3 eV)

    Energy Technology Data Exchange (ETDEWEB)

    Francés-Monerris, Antonio; Segarra-Martí, Javier; Merchán, Manuela; Roca-Sanjuán, Daniel, E-mail: Daniel.Roca@uv.es [Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, 46071 València (Spain)

    2015-12-07

    Low-energy (0-3 eV) ballistic electrons originated during the irradiation of biological material can interact with DNA/RNA nucleobases yielding transient-anion species which undergo decompositions. Since the discovery that these reactions can eventually lead to strand breaking of the DNA chains, great efforts have been dedicated to their study. The main fragmentation at the 0-3 eV energy range is the ejection of a hydrogen atom from the specific nitrogen positions. In the present study, the methodological approach introduced in a previous work on uracil [I. González-Ramírez et al., J. Chem. Theory Comput. 8, 2769-2776 (2012)] is employed to study the DNA canonical nucleobases fragmentations of N–H bonds induced by low-energy electrons. The approach is based on minimum energy path and linear interpolation of internal coordinates computations along the N–H dissociation channels carried out at the complete-active-space self-consistent field//complete-active-space second-order perturbation theory level. On the basis of the calculated theoretical quantities, new assignations for the adenine and cytosine anion yield curves are provided. In addition, the π{sub 1}{sup −} and π{sub 2}{sup −} states of the pyrimidine nucleobases are expected to produce the temporary anions at electron energies close to 1 and 2 eV, respectively. Finally, the present theoretical results do not allow to discard neither the dipole-bound nor the valence-bound mechanisms in the range of energies explored, suggesting that both possibilities may coexist in the experiments carried out with the isolated nucleobases.

  9. Effective and absolute cross sections for low-energy (1-30 eV) electron interactions with condensed biomolecules

    Science.gov (United States)

    Zheng, Yi; Sanche, Léon

    2018-06-01

    Ionizing radiation is intensively used for therapeutic [e.g., radiotherapy, brachytherapy, and targeted radionuclide therapy (TRT)], as well as for diagnostic medical imaging purposes. In these applications, the radiation dose given to the patient should be known and controlled. In conventional cancer treatments, absorbed dose calculations rely essentially on scattering cross sections (CSs) of the primary high-energy radiation. In more sophisticated treatments, such as combined radio- and chemo-therapy, a description of the details of energy deposits at the micro- and nano-scopic level is preferred to relate dose to radiobiological effectiveness or to evaluate doses at the biomolecular level, when radiopharmaceuticals emitting short-range radiation are delivered to critical molecular components of cancer cells (e.g., TRT). These highly radiotoxic compounds emit large densities of low-energy electrons (LEEs). More generally, LEE (0-30 eV) are emitted in large numbers by any type of high-energy radiation; i.e., about 30 000 per MeV of deposited primary energy. Thus, to optimize the effectiveness of several types of radiation treatments, the energy deposited by LEEs must be known at the level of the cell, nucleus, chromosome, or DNA. Such local doses can be evaluated by Monte Carlo (MC) calculations, which account event-by-event, for the slowing down of all generations of particles. In particular, these codes require as input parameters absolute LEE CSs for elastic scattering, energy losses, and direct damage to vital cellular molecules, particularly DNA, the main target of radiation therapy. In the last decade, such CSs have emerged in the literature. Furthermore, a method was developed to transform relative yields of damages into absolute CSs by measuring specific parameters in the experiments. In this review article, we first present a general description of dose calculations in biological media via MC simulation and give an overview of the CSs available from

  10. Irradiation of aluminium alloy materials with electron beam

    International Nuclear Information System (INIS)

    Konno, Osamu; Masumoto, Kazuyoshi

    1982-01-01

    It is a theme with a room for discussion to employ the stainless steel composed of longer half-life materials for the vacuum system of accelerators, from the viewpoint of radiation exposure. Therefore, it is desirable to use aluminium of shorter half-life in place of stainless steel. As a result of investigation on the above theme in the 1.2 GeV electron linac project in Tohoku University, it has been concluded that aluminium alloy vacuum chambers can reduce exposure dose by about one or two figures as compared with stainless steel ones. Of course, aluminium alloy contains trace amounts of Mg, Si, Ti, Cr, Mn, Fe, Zn, Cu and others. Therefore, four kinds of aluminium alloy considered to be usable have been examined for induced radioactivity by electron beam irradiation. Stainless steel SUS 304 has been also irradiated for comparison. Radiation energy has been 30 MeV and 200 MeV. When stainless steel and aluminium alloy were compared, aluminium alloy was very effective for reducing surface dose in low energy irradiation. In 200 MeV irradiation, the dose ratio of aluminium alloy to stainless steel became 1/30 to 1/100 after one week, though the dose difference between these two materials became smaller in 100 days or more after irradiation. If practical inspection and repair are implemented during the period from a few days to one week after shutdown, the aluminium alloy is preferable for exposure dose reduction even in high energy irradiation. (Wakatsuki, Y.)

  11. Temperature-dependent surface structure, composition, and electronic properties of the clean SrTiO3(111) crystal face: Low-energy-electron diffraction, Auger-electron spectroscopy, electron energy loss, and ultraviolet-photoelectron spectroscopy studies

    International Nuclear Information System (INIS)

    Lo, W.J.; Somorjai, G.A.

    1978-01-01

    Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO 2 surface, there are always significant concentrations of Ti 3+ in an annealed ordered SrTiO 3 (111) surface. This stable active Ti 3+ monolayer on top of a substrate with large surface dipole potential makes SrTiO 3 superior to TiO 2 when used as a photoanode in the photoelectrochemical cell

  12. Apparatus for electron beam irradiation of objects

    International Nuclear Information System (INIS)

    Dmitriev, S.P.; Ivanov, A.S.; Sviniin, M.P.; Fedotov, M.T.

    1984-01-01

    This patent provides an apparatus for electron beam irradiation of objects, comprising a shaper of a ribbon-shaped electron beam and a deflecting electromagnet having a frame-type magnetic circuit and used to direct said electron beam onto an irradiated object substantially at an angle of 90 degrees. The deflecting electromagnet has two poles extended over the width of the irradiated object and comprises two windings embracing said poles and connected to a d.c. source. The deflecting electromagnet is arranged in such a manner that the trajectories of the electrons at an area from the shaper to the electromagnet are inclined to the plane of the frame of its magnetic circuit

  13. Electron irradiation of dry food products

    International Nuclear Information System (INIS)

    Gruenewald, Th.

    1983-01-01

    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 deg 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 irradiation field in a closed conveyor system. (author)

  14. Electron irradiation of dry food products

    Energy Technology Data Exchange (ETDEWEB)

    Gruenewald, Th [Bundesbahn-Zentralamt, Minden (Germany, F.R.)

    1983-01-01

    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 deg 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 irradiation field in a closed conveyor system.

  15. Application of a Low-Energy Electron Beam as a Tool for ultrashort bunch length measurement in circular machines

    CERN Document Server

    Nikiforov, D A; Malyutin, D; Matveenko, A; Rusinov, K; Starostenko, A A

    2017-01-01

    A new diagnostic device designed for non-destructive ultrashort bunch length measurement is described. The operating principle of the device and the measuring technique are described. The possible scheme of arrangement of the device elements are described. The results of simulations of EBP application for different beams under investigation are presented. The quality requirements of the low energy testing beam are considered and resolving detector ability is determined.

  16. Spectroscopy of electron irradiated polymers in electron microscope

    International Nuclear Information System (INIS)

    Faraj, S.H.; Salih, S.M.

    1981-01-01

    The damage induced by energetic electrons in the course of irradiation of polymers in a transmission electron microscope was investigated spectroscopically. Damage on the molecular level has been detected at very low exposure doses. These effects have been induced by electron doses less than that received by the specimen when it is situated at its usual place of the specimen stage in the electron microscope by a factor of 1,000. (author)

  17. Impact of Coulomb potential on peak structures arising in momentum and low-energy photoelectron spectra produced in strong-field ionization of laser-irradiated atoms

    Science.gov (United States)

    Pyak, P. E.; Usachenko, V. I.

    2018-03-01

    The phenomenon of pronounced peak structure(s) of longitudinal momentum distributions as well as a spike-like structure of low-energy spectra of photoelectrons emitted from laser-irradiated Ar and Ne atoms in a single ionization process is theoretically studied in the tunneling and multiphoton regimes of ionization. The problem is addressed assuming only the direct above-threshold ionization (ATI) as a physical mechanism underlying the phenomenon under consideration (viz. solely contributing to observed photoelectron momentum distributions (PMD)) and using the Coulomb-Volkov (CV) ansatz within the frame of conventional strong-field approximation (SFA) applied in the length-gauge formulation. The developed CV-SFA approach also incorporates the density functional theory essentially exploited for numerical composition of initial (laser-free) atomic state(s) constructed from atomic orbitals of Gaussian type. Our presented CV-SFA based (and laser focal-volume averaged) calculation results proved to be well reproducing both the pronounced double-peak and/or ATI-like multi-peak structure(s) experimentally observed in longitudinal PMD under conditions of tunneling and/or multiphoton regime, respectively. In addition, our CV-SFA results presented for tunneling regime also suggest and remarkably reproduce a pronounced structure observed in relevant experiments as a ‘spike-like’ enhanced maximum arising in low-energy region (around the value of about 1 eV) of photoelectron spectra. The latter consistency allows to identify and interpret these results as the so-called low-energy structure (LES) since the phenomenon proved to appear as the most prominent if the influence of Coulomb potential on photoelectron continuum states is maximally taken into account under calculations (viz. if the parameter Z in CV’s functions is put equal to 1). Moreover, the calculated LES proved to correspond (viz., established as closely related) to the mentioned double-peak structure arising

  18. Defect reactions on the phosphorus sublattice in low-temperature electron-irradiated InP

    International Nuclear Information System (INIS)

    Sibille, A.; Suski, J.

    1985-01-01

    This Rapid Communication describes several thermally or electronically stimulated defect reactions involving the dominant deep centers in low-temperature (25--300 K) electron-irradiated InP. Some of these reactions result in an increased concentration of the centers, thereby revealing the existence of a secondary production mechanism of the related defects. Low-energy irradiations allows one to select the type of the ejected atom (P) and gives direct evidence that only a phosphorus species, interstitial or vacancy, is involved in the creation-reaction-annealing events

  19. Subthreshold displacement damage in copper--aluminum alloys during electron irradiation

    International Nuclear Information System (INIS)

    Drosd, R.; Kosel, T.; Washburn, J.

    1976-12-01

    During electron irradiation at low energies which results in a negligible damage rate in a pure material, lighter solute atoms are displaced, which may in turn indirectly displace solvent atoms by a focussed replacement collision or an interstitial diffusion jump. The extent to which lighter solute atoms contribute to the subthreshold damage rate has been examined by irradiating copper--aluminum alloys at high temperatures in a high voltage electron microscope. The damage rate, as measured by monitoring the growth rate of dislocation loops, at 300 kV was found to increase linearly with the aluminum concentration

  20. Irradiation of Gemstones using Electron Beam

    International Nuclear Information System (INIS)

    Sarada Idris; Mohd Suhaimi Jusoh; Siti Aiasah Hashim

    2011-01-01

    Gemstone irradiation treatment using radiation is one of the studies conducted in the ALURTRON. The purpose of radiation is to study the effects of radiation on the gems. Through studies conducted on freshwater pearls and stones such as Topaz, Kunzite, TOURMALINE, Aquamarine, Quartz and so on, electron beam irradiation method can highlight the jewel colors but also to reduce the effects of haze on gemstones. The dose of radiation used is 25 kGy to 200 kGy. (author)

  1. Spectra of electrons emitted as a result of the sticking and annihilation of low energy positrons to the surfaces of graphene and highly oriented pyrolytic graphite (HOPG)

    Science.gov (United States)

    Chrysler, M.; Chirayath, V.; McDonald, A.; Lim, Z.; Shastry, K.; Gladen, R.; Fairchild, A.; Koymen, A.; Weiss, A.

    Positron annihilation induced Auger electron spectroscopy (PAES) was used to study the positron induced low energy electron spectra from HOPG and a sample composed of 6-8 layers of graphene grown on polycrystalline copper. A low energy (~2eV) beam of positrons was used to implant positrons into a surface localized state on the graphene and HOPG samples. Measurements of the energy spectra of the positron induced electrons obtained using a TOF spectrometer indicate the presence of an annihilation induced KLL C Auger peak (at ~263 eV) along with a narrow low energy secondary peak due to an Auger mediated positron sticking (AMPS) process. A broad spectral feature was also observed below ~15 eV which we believe may be due to a VVV C Auger transition not previously observed. The energy dependence of the integrated intensity of the AMPS peak was measured for a series of incident positron kinetic energies ranging from ~1.5 eV up to 11 eV from which the binding energy of the surface localized positron state on graphene and HOPG was estimated. The implication of our results regarding the applicability of AMPS and PAES to the study of graphene surfaces and interfaces will be discussed. This work was supported by NSF Grant No. DMR 1508719 and DMR 1338130.

  2. MCNPX calculations for electron irradiated semiconductor detectors

    International Nuclear Information System (INIS)

    Sedlackova, K.; Necas, V.; Sagatova, A.; Zatko, B.

    2014-01-01

    This study aimed to treat some practical problems of (not only) semiconductor material irradiation by high energy electron beam using MCNPX simulation code. The relation between the absorbed dose and the fluency was found and the energy distribution of electron flux density was simulated on the top and back side of 270 μm thick GaAs, SiC and Si detectors. Furthermore, the dose depth profiles were calculated for GaAs, SiC and Si materials irradiated by 4 and 5 MeV electron beams. For the GaAs detector, a very good agreement with the experiment was shown. To match the absolute values of the absorbed dose with experimentally obtained values, the electron source emissivity has to be determined in relation to the electron beam setting parameters. (authors)

  3. Electron-irradiation-induced phase transformation in alumina

    International Nuclear Information System (INIS)

    Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

    2010-01-01

    In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

  4. Electron beam irradiation technology for environmental conservation

    International Nuclear Information System (INIS)

    Tokunaga, Okihiro; Arai, Hidehiko; Hashimoto, Shoji

    1992-01-01

    This paper reviews research and development of application of electron beam (EB) irradiation technology for treatment of flue gas and waste water, and for disinfection of sewage sludge. Feasibility studies on EB purification of flue gases have been performed with pilot-scale experiments in Japan, the USA and Germany, and is being carried out in Poland for flue gases from iron-sintering furnaces or coal burning boilers. Based on results obtained by experiments using simulated flue gas, pilot scale test for treatment of flue gas of low-sulfur containing coal combustion has recently started in Japan. Organic pollutants in waste water and ground water have been found to be decomposed by EB irradiation. Synergetic effect of EB irradiation and ozone addition was found to improve the decomposition efficiency. Electron beam irradiation technology for disinfection of water effluent from water treatment plants was found to avoid formation of chlorinated organic compounds which are formed in using chlorine. Efficient process for composting of sewage sludge disinfected by EB irradiation has been developed by small scale and pilot scale experiments. In the new process, disinfection by EB irradiation and composing can be done separately and optimum temperature for composting can be, therefore, selected to minimize period of composting. (author)

  5. Ultrafine tungsten as a plasma-facing component in fusion devices: effect of high flux, high fluence low energy helium irradiation

    International Nuclear Information System (INIS)

    El-Atwani, O.; Gonderman, Sean; Allain, J.P.; Efe, Mert; Klenosky, Daniel; Qiu, Tian; De Temmerman, Gregory; Morgan, Thomas; Bystrov, Kirill

    2014-01-01

    This work discusses the response of ultrafine-grained tungsten materials to high-flux, high-fluence, low energy pure He irradiation. Ultrafine-grained tungsten samples were exposed in the Pilot-PSI (Westerhout et al 2007 Phys. Scr. T128 18) linear plasma device at the Dutch Institute for Fundamental Energy Research (DIFFER) in Nieuwegein, the Netherlands. The He flux on the tungsten samples ranged from 1.0 × 10 23 –2.0 × 10 24  ions m −2  s −1 , the sample bias ranged from a negative (20–65) V, and the sample temperatures ranged from 600–1500 °C. SEM analysis of the exposed samples clearly shows that ultrafine-grained tungsten materials have a greater fluence threshold to the formation of fuzz by an order or magnitude or more, supporting the conjecture that grain boundaries play a major role in the mechanisms of radiation damage. Pre-fuzz damage analysis is addressed, as in the role of grain orientation on structure formation. Grains of (1 1 0) and (1 1 1) orientation showed only pore formation, while (0 0 1) oriented grains showed ripples (higher structures) decorated with pores. Blistering at the grain boundaries is also observed in this case. In situ TEM analysis during irradiation revealed facetted bubble formation at the grain boundaries likely responsible for blistering at this location. The results could have significant implications for future plasma-burning fusion devices given the He-induced damage could lead to macroscopic dust emission into the fusion plasma. (paper)

  6. Wavelength dependence of momentum-space images of low-energy electrons generated by short intense laser pulses at high intensities

    International Nuclear Information System (INIS)

    Maharjan, C M; Alnaser, A S; Litvinyuk, I; Ranitovic, P; Cocke, C L

    2006-01-01

    We have measured momentum-space images of low-energy electrons generated by the interaction of short intense laser pulses with argon atoms at high intensities. We have done this over a wavelength range from 400 to 800 nm. The spectra show considerable structure in both the energy and angular distributions of the electrons. Some, but not all, energy features can be identified as multi-photon resonances. The angular structure shows a regularity which transcends the resonant structure and may be due instead to diffraction. The complexity of the results defies easy model-dependent interpretations and invites full solutions to Schroedinger's equation for these systems

  7. AECL IMPELA electron beam industrial irradiators

    International Nuclear Information System (INIS)

    Labrie, J.P.; Drewell, N.H.; Ebrahim, N.A.; Lawrence, C.B.; Mason, V.A.; Ungrin, J.; White, B.F.

    1989-01-01

    A family of industrial irradiators is being developed by AECL to cover an electron-beam energy range from 5 to 18 MeV at beam powers between 20 and 250 kW. The IMPELA family of irradiators is designed for push button, reliable operation. The major irradiator components are modular, allowing for later upgrades to meet increased demands in either electron or X-ray mode. Interface between the control system, irradiator availability and dose quality assurance is in conformance with the most demanding specifications. The IMPELA irradiators use a klystron-driven, standing-wave, L-band accelerator structure with direct injection from a rugged, triode electron gun. Direct control of the accelerating field during the beam pulse ensures constant output beam energy, independent of beam power. The first member of the family, the IMPELA 10/50 (10 MeV, 50 kW), is in the final stages of assembly at Chalk River Nuclear Laboratories. The IMPELA 10/50 is constructed around a 3.25 m long, high-power-capacity accelerator structure operated at a duty factor of 5%. Beam loading exceeds 60%. The rf power is provided by a 2 MW/150 kW modulated-anode klystron protected from load mismatches by a circulator. This prototype will be used to demonstrate the reliability and dose uniformity targets of the IMPELA family. Full beam operation of the IMPELA 10/50 is scheduled for early 1989. (orig.)

  8. Degradation of Cu(In, Ga)Se{sub 2} thin-film solar cells due to the ionization effect of low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Shirou, E-mail: kawakita.shirou@jaxa.jp [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Imaizumi, Mitsuru [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Ishizuka, Shogo; Shibata, Hajime; Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Okuda, Shuichi [Osaka Prefecture University (OPU), Sakai, Osaka 599-8570 (Japan); Kusawake, Hiroaki [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan)

    2015-05-01

    Cu (In, Ga)Se{sub 2} (CIGS) solar cells were irradiated with 100 keV electrons to reveal the characteristics of created radiation defects. 100 keV electrons cannot produce any displacement defects in CIGS. Low-fluence electrons improve the electrical performance of the CIGS solar cells due to the change in the conductive type of donor to acceptor in a metastable defect, which is equivalent to the light-soaking effect. However, high fluence electrons cause the cell performance to decline. From analysis based on changes in carrier density and electroluminescence, defects causing the decline in performance include donor- and non-radiative types. In addition, red-on-bias experiments showed an increase in III{sub Cu} defects due to electron irradiation. Based on these results, the degradation in the electrical performance of the CIGS solar cells irradiated with high electron fluence would be attributable to a change in the conductive type of III{sub Cu} defects. - Highlights: • Cu(In,Ga)Se2 Solar cells were irradiated with 100 and 250 keV electrons at low temperature. • These electrons degraded the electrical performance of Cu(In,Ga)Se2 sola cells. • The electrons induced ⅢCu defects in Cu(In,Ga)Se2.

  9. Tuning of the optical properties of In-rich In{sub x}Ga{sub 1−x}N (x=0.82−0.49) alloys by light-ion irradiation at low energy

    Energy Technology Data Exchange (ETDEWEB)

    De Luca, Marta; Polimeni, Antonio; Capizzi, Mario [Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Pettinari, Giorgio [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Ciatto, Gianluca; Fonda, Emiliano [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif sur Yvette Cedex (France); Amidani, Lucia; Boscherini, Federico [Department of Physics and CNISM, University of Bologna, V. le C. Berti Pichat 6/2, 40127 Bologna (Italy); Filippone, Francesco; Bonapasta, Aldo Amore [CNR-Istituto di Struttura della Materia (ISM), Via Salaria Km 29.5, CP 10, I-00016 Monterotondo Stazione (Italy); Knübel, Andreas; Cimalla, Volker; Ambacher, Oliver [Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg (Germany); Giubertoni, Damiano; Bersani, Massimo [CMM - Fondazione Bruno Kessler, Trieste, via Sommarive 18, 38100, Povo Trento (Italy)

    2013-12-04

    The effects of low-energy irradiation by light ions (H and He) on the properties of In-rich In{sub x}Ga{sub 1−x}N alloys are investigated by optical and structural techniques. H-irradiation gives rise to a remarkable blue-shift of light emission and absorption edge energies. X-ray absorption measurements and first-principle calculations address the microscopic origin of these effects.

  10. Tuning of the optical properties of In-rich InxGa1−xN (x=0.82−0.49) alloys by light-ion irradiation at low energy

    International Nuclear Information System (INIS)

    De Luca, Marta; Polimeni, Antonio; Capizzi, Mario; Pettinari, Giorgio; Ciatto, Gianluca; Fonda, Emiliano; Amidani, Lucia; Boscherini, Federico; Filippone, Francesco; Bonapasta, Aldo Amore; Knübel, Andreas; Cimalla, Volker; Ambacher, Oliver; Giubertoni, Damiano; Bersani, Massimo

    2013-01-01

    The effects of low-energy irradiation by light ions (H and He) on the properties of In-rich In x Ga 1−x N alloys are investigated by optical and structural techniques. H-irradiation gives rise to a remarkable blue-shift of light emission and absorption edge energies. X-ray absorption measurements and first-principle calculations address the microscopic origin of these effects

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

    Science.gov (United States)

    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.

  12. User Support of Electron Irradiation Facility

    International Nuclear Information System (INIS)

    Park, S. H.; Cha, H. K.; Lee, B. C.

    2007-06-01

    The KAERI (Korean Atomic Energy Research Institute) high-power electron beam irradiation facility, operating at the energies between 0.3 MeV and 10 MeV,has provided irradiation services to users in industries, universities, and institutes via 'Project of utilization and cooperation of users of a large research facility' since 2004. A great attraction of many researchers, almost 750 persons so far according to surveys, to e-beam irradiation technology as well as the growth of participants on Workshop on Electron Beam Applications from 121 to 176 indicate the increase of demands of irradiation service. Comparing to the cases of advanced nations in this area, such as America, Japan, China, and Russia, Korea is relatively much behind in radiation technology. It is mainly due to the lack of governmental supports and investments. Active support and investment on construction and operation of electron beam user facilities would be principal factors on developments of advanced technologies. In this project, we would like to satisfy users' requests by developing the effective managing and operating system for prompt services, processes, and QA and to ultimately assist users to create additional new results, by maximizing the utilization of all available resources and activating the developments of technologies of electron beam processing

  13. Field-orientation dependence of low-energy quasiparticle excitations in the heavy-electron superconductor UBe(13).

    Science.gov (United States)

    Shimizu, Yusei; Kittaka, Shunichiro; Sakakibara, Toshiro; Haga, Yoshinori; Yamamoto, Etsuji; Amitsuka, Hiroshi; Tsutsumi, Yasumasa; Machida, Kazushige

    2015-04-10

    Low-energy quasiparticle excitations in the superconducting (SC) state of UBe_{13} were studied by means of specific-heat (C) measurements in a rotating field. Quite unexpectedly, the magnetic-field dependence of C(H) is linear in H with no angular dependence at low fields in the SC state, implying that the gap is fully open over the Fermi surfaces, in stark contrast to previous expectations. In addition, a characteristic cubic anisotropy of C(H) was observed above 2 T with a maximum (minimum) for H∥[001] ([111]) within the (11[over ¯]0) plane, in the normal as well as in the SC states. This oscillation possibly originates from the anisotropic response of the heavy quasiparticle bands, and might be a key to understand the unusual properties of UBe_{13}.

  14. Size Control Technology of Silver Nanoparticles Using Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Kang, Hyun Suk; Kim, Byungnam; Kim, Hye Won; Koo, Yong Hwan; Lee, Byung Cheol; Park, Ji Hyun; Bae, Hyung Bin; Park, Changmoon

    2013-01-01

    The manufacturing of silver nanoparticles using an electron beam is easy, fast, and highly productive, and it is possible at room temperature with no chemical residuals. Its various advantages therefore make this an important method for manufacturing nanoparticles such as silver, copper, and platinum. In particular, despite the use of electron beam irradiation, the results show that this method makes it possible to produce silver nanoparticles at low cost since low beam energy and low doses are used. This means that middle and high-energy electron beam accelerators are very expensive, but a low-energy electron beam accelerator has a relatively low cost of around 4-5 times, and mass production for a flow reaction without the need for extra radiation shielding is possible. Silver nanoparticles are of great interest to many researchers owing to their ability to be used in many applications such as catalysis, nanoelectronics, optical filters, electromagnetic interference shielding, surface Raman scattering, medical supplies, fabrics, cosmetics, hygiene and kitchen supplies, and electric home appliances

  15. Size Control Technology of Silver Nanoparticles Using Electron Beam Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyun Suk; Kim, Byungnam; Kim, Hye Won; Koo, Yong Hwan; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Ji Hyun [Univ. of Science and Technology, Daejeon (Korea, Republic of); Bae, Hyung Bin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Park, Changmoon [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-12-15

    The manufacturing of silver nanoparticles using an electron beam is easy, fast, and highly productive, and it is possible at room temperature with no chemical residuals. Its various advantages therefore make this an important method for manufacturing nanoparticles such as silver, copper, and platinum. In particular, despite the use of electron beam irradiation, the results show that this method makes it possible to produce silver nanoparticles at low cost since low beam energy and low doses are used. This means that middle and high-energy electron beam accelerators are very expensive, but a low-energy electron beam accelerator has a relatively low cost of around 4-5 times, and mass production for a flow reaction without the need for extra radiation shielding is possible. Silver nanoparticles are of great interest to many researchers owing to their ability to be used in many applications such as catalysis, nanoelectronics, optical filters, electromagnetic interference shielding, surface Raman scattering, medical supplies, fabrics, cosmetics, hygiene and kitchen supplies, and electric home appliances.

  16. Theoretical study of the transmission of low-energy (0-10 eV) electrons through thin-film organic molecular solids: benzene

    International Nuclear Information System (INIS)

    Goulet, T.; Jay-Gerin, J.-P.

    1986-01-01

    A theoretical study of the transmission of low-energy (0 to 10 eV) electrons incident from vacuum through thin-film organic molecular solids deposited on a cold metal substrate is presented and developed for the specific case of solid benzene. In essence, using a semiclassical description of electron transport in solids with an energy-independent scattering mean free path and assuming an isotropic electron scattering, the behavior of a penetrating electron in the film is simulated when a large number of scattering events are present. The good agreement between the calculated electron transmission spectra and those obtained experimentally indicates that our study provides a realistic description of the electron transport in the film, and accounts for the influence of the various electron-molecule scattering processes upon the energy dependence of the transmitted current. In particular, we show that the excitonic subionization energy losses are at the origin of the main structures of the observed electron transmission spectra. It is also shown that our study can successfully be used to estimate the probabilities of the various electron scattering processes which occur in the film, as well as the electron mean free path (l). For solid benzene, l is about 8 A in the considered electron energy range. (author)

  17. Low-energy electron-induced dissociation in condensed-phase L-cysteine I: Desorption of anions from chemisorbed films

    International Nuclear Information System (INIS)

    Alizadeh, E; Rowntree, P A; Massey, S; Sanche, L

    2015-01-01

    Among amino acids, cysteine has been widely studied, becoming a standard for molecular self-assembly experiments, because its mercapto group (-SH) allows the formation of self-assembled monolayers (SAMs) on metal surfaces. Dissociative electron attachment (DEA) on L-cysteine SAMs is investigated utilizing a time-of-flight mass spectrometer coupled with a low-energy electron gun. The results show that electrons with kinetic energies of 3 to 15 eV attach to L-cysteine producing anionic fragments of different masses (e.g., H - , O - , OH - , S - , SH - ) via dissociation of intermediate transient anions. The anion yield functions exhibited purely resonant behaviour with electron energies below 15 eV, indicating that the formation of transient anions is the predominant mechanism of production of anionic fragments from L-cysteine dissociation. (paper)

  18. Low-energy electron-induced dissociation in condensed-phase L-cysteine II: a comparative study on anion desorption from chemisorbed and physisorbed films

    International Nuclear Information System (INIS)

    Alizadeh, E.; Rowntree, P.A.; Massey, S.; Sanche, L.

    2016-01-01

    In recent years it has become apparent that dissociative attachment of low energy electrons (DEA) is important for the description of radiation damage to biologically relevant molecules and living cells. Due to its multifunctional structure, cysteine is becoming an ideal model molecule for investigating the complex interactions of proteins with metallic surfaces such as gold nanoparticles. We report herein the results of low-energy electron induced degradation of L-cysteine films, chemisorbed on a gold substrate via the thiol group or physisorbed into a clean gold surface. The data were recorded under ultra-high vacuum conditions at room temperature. Anion yields desorbed from these films by the impact of 0.5 to 19 eV electrons provide clear evidence of the efficient decomposition of this amino acid via dissociative electron attachment (i.e., from dissociation of intermediate transient anions located between 5 and 14 eV). The peaks in the desorbed-anion yield functions, associated with DEA, are superimposed on a continuously rising signal attributed to dipolar dissociation. Similar to the results previously observed from physisorbed films, light anionic species, with masses lower than 35 amu, have been detected. In addition, we measured for first time fragments at 14 amu (CH_2"-) and 15 amu (CH_3"-) desorbing from physisorbed films, as well as heavier fragments of mass 45 and 46 amu desorbing from chemisorbed films

  19. Thermal conductivity of electron-irradiated graphene

    Science.gov (United States)

    Weerasinghe, Asanka; Ramasubramaniam, Ashwin; Maroudas, Dimitrios

    2017-10-01

    We report results of a systematic analysis of thermal transport in electron-irradiated, including irradiation-induced amorphous, graphene sheets based on nonequilibrium molecular-dynamics simulations. We focus on the dependence of the thermal conductivity, k, of the irradiated graphene sheets on the inserted irradiation defect density, c, as well as the extent of defect passivation with hydrogen atoms. While the thermal conductivity of irradiated graphene decreases precipitously from that of pristine graphene, k0, upon introducing a low vacancy concentration, c reduction of the thermal conductivity with the increasing vacancy concentration exhibits a weaker dependence on c until the amorphization threshold. Beyond the onset of amorphization, the dependence of thermal conductivity on the vacancy concentration becomes significantly weaker, and k practically reaches a plateau value. Throughout the range of c and at all hydrogenation levels examined, the correlation k = k0(1 + αc)-1 gives an excellent description of the simulation results. The value of the coefficient α captures the overall strength of the numerous phonon scattering centers in the irradiated graphene sheets, which include monovacancies, vacancy clusters, carbon ring reconstructions, disorder, and a rough nonplanar sheet morphology. Hydrogen passivation increases the value of α, but the effect becomes very minor beyond the amorphization threshold.

  20. Extra Low ENergy Antiproton

    CERN Multimedia

    To produce dense antiproton beams at very low energies (110 keV), it has been proposed to install a small decelerator ring between the existing AD ring and the experimental area. Phase-space blowup during deceleration is compensated by electron cooling such that the final emittances are comparable to the 5MeV beam presently delivered by the AD. An immediate consequence is a significant increase in the number of trapped antiprotons at the experiments as outlined in the proposal CERN/SPSC-2009-026; SPCS-P-338. This report describes the machine parameters and layout of the proposal ELENA (Extra Low ENergy Antiproton)ring also gives an approximate estimate of cost and manpower needs. Since the initial estimate, published in 2007 (CERN-AB-2007-079), the ELENA design has evolved considerably. This is due to a new location in the AD hall to acommodate for the possibility of another experimental zone, as suggested by the SPCS, and also due to improvements in the ring optics and layout. The cost estimate that is prese...

  1. Polymeric materials obtained by electron beam irradiation

    International Nuclear Information System (INIS)

    Dragusin, M.; Moraru, R.; Martin, D.; Radoiu, M.; Marghitu, S.; Oproiu, C.

    1995-01-01

    Research activities in the field of electron beam irradiation of monomer aqueous solution to produce polymeric materials used for waste waters treatment, agriculture and medicine are presented. The technologies and special features of these polymeric materials are also described. The influence of the chemical composition of the solution to ba irradiated, absorbed dose level and absorbed dose rate level are discussed. Two kinds of polyelectrolytes, PA and PV types and three kinds of hydrogels, pAAm, pAAmNa and pNaAc types, the production of which was first developed with IETI-10000 Co-60 source and then adapted to the linacs built in Accelerator Laboratory, are described. (author)

  2. Correlation effects on double electron capture in highly-charged, low-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Meyer, F.W.; Griffin, D.C.; Havener, C.C.; Huq, M.S.; Phaneuf, R.A.; Swenson, J.K.; Stolterfoht, N.

    1987-01-01

    The method of zero-degree Auger electron spectroscopy has been used to study two-electron excited states populated in slow double capture collisions of highly charged ions with He and H 2 . The focus of this study is on production of autoionization electrons originating from the non-equivalent 1s 2 2pnl electron configurations in comparison with electron production resulting from the Auger decay of (near) equivalent 1s 2 nln'l' (with n∼n') configurations. It is shown that production of non-equivalent electron configurations is significant and involves electron-electron correlation effects whose analysis leads beyond the independent-particle model. Recent results that include a measurement at non-zero angles are presented to illustrate the angular dependence of electron emission from non-equivalent electron configurations, as well as the dependence on projectile charge state and target species. Comparison of high resolution scans over two lines of the 1s 2 2pnl sequence for the O 6+ + He system with accurate transition energy calculations shows preferential population of high angular momentum substation

  3. Electron irradiation effects in amorphous antimony thin films obtained by cluster-beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, G.; Treilleux, M.; Santos Aires, F.; Cabaud, B.; Melinon, P.; Hoareau, A. (Lyon-1 Univ., 69 - Villeurbanne (France))

    1991-03-01

    In order to understand the differences existing between films obtained with a classical molecular beam deposition (MBD) and the new low-energy cluster beam deposition (LECBD), transmission electron microscopy has been used to characterize the first stages of antimony LECBD. Antimony deposits are discontinuous and amorphous up to 2 nm in thickness. They are formed with isolated amorphous antimony particles surrounded by an amorphous antimony oxide shell. Moreover, under electron beam exposure in the microscope, an amorphous-crystal transformation has been observed in the oxide shell. Electron irradiation induces the formation of a crystallized antimony oxide (Sb{sub 2}O{sub 3}) around the amorphous antimony core. (author).

  4. Electron beam irradiation: laboratory and field studies of cowpea seeds

    International Nuclear Information System (INIS)

    Srinivasan, K.; Chauhan, S.K.; Prasad, T.V.; Pramod, R.; Verma, V.P.; Petwal, V.; Dwivedi, J.; Bhalla, S.

    2015-01-01

    Cowpea (Vigna unguiculata) rich in protein and vitamins is emerging as one of the most important food legumes to tackle malnutrition. Pulse beetles (Callosobruchus chinensis and C. maculatus) are the pests of economic importance causing enormous losses during storage. Although various pest management strategies exist for the control of these pests, environmental concerns necessitate developing ecofriendly strategies. Electron beam (EB) irradiation has the potential to be a viable, non-chemical, residue-free strategy for management of pulse beetles during storage, but higher doses affect seed germination and viability. Hence, the present investigation was taken up to analyse the dosage effect of the irradiation on seed attributes of cowpea. Healthy cowpea seeds were irradiated with low energy electrons at different doses viz., 180, 360, 540, 720, 900, 1080, 1260, 1440 and 1620 Gy at 500 keV using the EB Accelerator facility at Raja Ramanna Centre for Advanced Technology, Indore. EB irradiated seeds were tested for physiological viz., germination, seedling vigour and vigour index and biochemical parameters viz., electrical conductivity of seed leachate, seed viability/tetrazolium test and dehydrogenase activity. Germination and vigour of the irradiated seeds were evaluated as per the ISTA Rules (ISTA, 1996). Vigour index was calculated as the product of germination percentage and seedling vigour. About 3,000 irradiated seeds from each dose were grown in the field at the Experimental farm, National Bureau of Plant Genetic Resources, New Delhi. Seeds harvested from 1500 individual plants of M 1 generation from each dose (50 seeds from each plant individually) were sown in next season and observed for chlorophyll mutations, if any. Results revealed that doses upto 1080 Gy (88%) did not affect the germination of cowpea seeds drastically as compared to untreated seeds (98%). Lower doses viz., 180 and 360 Gy had no impact on vigour components while higher doses (1080 Gy

  5. High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

    International Nuclear Information System (INIS)

    Bizen, Teruhiko; Asano, Yoshihiro; Marechal, Xavier-Marie; Seike, Takamitsu; Aoki, Tsuyoshi; Fukami, Kenji; Hosoda, Naoyasu; Yonehara, Hiroto; Takagi, Tetsuya; Hara, Toru; Tanaka, Takashi; Kitamura, Hideo

    2007-01-01

    High-energy electron-beam bombardment of Nd 2 Fe 14 B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small

  6. High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

    Energy Technology Data Exchange (ETDEWEB)

    Bizen, Teruhiko [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)]. E-mail: bizen@spring8.or.jp; Asano, Yoshihiro [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Marechal, Xavier-Marie [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Seike, Takamitsu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Aoki, Tsuyoshi [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Fukami, Kenji [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoda, Naoyasu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yonehara, Hiroto [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takagi, Tetsuya [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Toru [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Tanaka, Takashi [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kitamura, Hideo [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2007-05-11

    High-energy electron-beam bombardment of Nd{sub 2}Fe{sub 14}B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small.

  7. Surface structure of Bi2Se3(111) determined by low-energy electron diffraction and surface x-ray diffraction

    DEFF Research Database (Denmark)

    dos Reis, Diogo Duarte; Barreto, Lucas; Bianchi, Marco

    2013-01-01

    The surface structure of the prototypical topological insulator Bi2Se3 is determined by low-energy electron diffraction and surface x-ray diffraction at room temperature. Both approaches show that the crystal is terminated by an intact quintuple layer. Specifically, an alternative termination by ...... by a bismuth bilayer is ruled out. Surface relaxations obtained by both techniques are in good agreement with each other and found to be small. This includes the relaxation of the van der Waals gap between the first two quintuple layers....

  8. Structure determination of disordered organic molecules on surfaces from the Bragg spots of low-energy electron diffraction and total energy calculations

    International Nuclear Information System (INIS)

    Poon, H.C.; Weinert, M.; Saldin, D.K.; Stacchiola, D.; Zheng, T.; Tysoe, W.T.

    2004-01-01

    We show that an analysis of the intensity versus energy variation of Bragg spots due to low-energy electron diffraction from a disordered overlayer of molecules on a crystal surface allows a much more convenient method of determining the local adsorption geometries of such molecules than previously analyzed weak diffuse diffraction patterns. For the case of methanol on Pd(111), we show that the geometry determined by this means from experimental diffraction data is in excellent agreement with the predictions of density functional total energy calculations

  9. Positron lifetime studies of electron irradiated copper

    International Nuclear Information System (INIS)

    Hadnagy, T.D.

    1976-01-01

    Single-crystal copper was irradiated with 4.5-MeV electrons producing simple Frenkel defects as well as a significant concentration of divacancies. Mean positron lifetime characteristics, which are sensitive to the presence of vacancies and multivacancies in copper, was monitored after isochronal anneals between 80 and 800 0 K to determine the relative change of characteristic mean lifetimes and their associated intensities. Also a study of the dependence of the mean positron lifetime on the total electron fluence was made and compared with existing theories relating these lifetimes to vacancy or multivacancy concentrations. Numerical data from curve fitting procedures using a conventional trapping model for defect-induced changes in positron lifetimes indicate that upon irradiation with 4.5-MeV electrons at 80 0 K, about 8 percent of the defects produced are divacancy units. Divacancy units appear to be several times more effective in trapping positrons than are monovacancies. Further, the experimental data suggest that the stage III annealing processes in electron-irradiated copper most probably involve the motion and removal of both monovacancies and divacancies. A conglomerate (multivacancy) unit appears to exist as a stable entity even after annealing procedures are carried out at temperatures slightly above the stage III region. Such a stable unit could serve as a nucleation center for the appearance of voids

  10. Energy deposition model for low-energy electrons (10-10 000 eV) in air

    International Nuclear Information System (INIS)

    Roldan, A.; Perez, J.M.; Williart, A.; Blanco, F.; Garcia, G.

    2004-01-01

    An energy deposition model for electrons in air that can be useful in microdosimetric applications is presented in this study. The model is based on a Monte Carlo simulation of the single electron scattering processes that can take place with the molecular constituents of the air in the energy range 10-10 000 eV. The input parameters for this procedure have been the electron scattering cross sections, both differential and integral. These parameters were calculated using a model potential method which describes the electron scattering with the molecular constituent of air. The reliability of the calculated integral cross section values has been evaluated by comparison with direct total electron scattering cross-section measurements performed by us in a transmission beam experiment. Experimental energy loss spectra for electrons in air have been used as probability distribution functions to define the electron energy loss in single collision events. The resulting model has been applied to simulate the electron transport through a gas cell containing air at different pressures and the results have been compared with those observed in the experiments. Finally, as an example of its applicability to dosimetric issues, the energy deposition of 10 000 eV by means of successive collisions in a free air chamber has been simulated

  11. Direct Detection and Imaging of Low-Energy Electrons with Delta-Doped Charge-Coupled Devices

    Science.gov (United States)

    Nikzad, S.; Yu, Q.; Smith, A. L.; Jones, T. J.; Tombrello, T. A.; Elliott, S. T.

    1998-01-01

    We report the use fo delta-doped charge-coupled devices (CCDs) for direct detection of electrons in the 50-1500 eV energy range. These are the first measurements with a solid state device to detect electrons in this energy range.

  12. Stress relaxation under cyclic electron irradiation

    International Nuclear Information System (INIS)

    Bystrov, L.N.; Reznitskij, M.E.

    1990-01-01

    The kinetics of deformation process in a relaxating sample under 2 MeV electron cyclic irradiation was studied experimentally. The Al-Mg alloys with controllable and different (in dislocation density precipitate presence and their character) structure were used in experiments. It was established that after the beam was switched on the deformation rate increased sharply and then, during prolonged irradiation, in a gradual manner. After the switching-off the relaxation rate decreases by jumps up to values close to extrapolated rates of pre-radiation relaxation. The exhibition of these effects with radiation switching-off and switchin-on is dependent on the initial rate of thermal relaxation, the test temperature, the preliminary cold deformation and the dominating deformation dislocation mechanism. The preliminary cold deformation and test temperature elevation slightly decrease the effect of instantaneous relaxation acceleration with the irradiation switch-on. 17 refs., 5 figs

  13. Low-energy electron-induced dissociation in condensed-phase L-cysteine II: a comparative study on anion desorption from chemisorbed and physisorbed films

    Science.gov (United States)

    Alizadeh, Elahe; Massey, Sylvain; Sanche, Léon; Rowntree, Paul A.

    2016-04-01

    Due to its multifunctional structure, cysteine is becoming an ideal model molecule for investigating the complex interactions of proteins with metallic surfaces such as gold nanoparticles. We report herein the results of low-energy electron induced degradation of L-cysteine films, chemisorbed on a gold substrate via the thiol group or physisorbed into a clean gold surface. The data were recorded under ultra-high vacuum conditions at room temperature. Anion yields desorbed from these films by the impact of 0.5 to 19 eV electrons provide clear evidence of the efficient decomposition of this amino acid via dissociative electron attachment (i.e., from dissociation of intermediate transient anions located between 5 and 14 eV). The peaks in the desorbed-anion yield functions, associated with DEA, are superimposed on a continuously rising signal attributed to dipolar dissociation. Similar to the results previously observed from physisorbed films, light anionic species, with masses lower than 35 amu, have been detected. In addition, we measured for first time fragments at 14 amu (CH2-) and 15 amu (CH3-) desorbing from physisorbed films, as well as heavier fragments of mass 45 and 46 amu desorbing from chemisorbed films. Contribution to the Topical Issue "Low-Energy Interactions related to Atmospheric and Extreme Conditions", edited by S. Ptasinska, M. Smialek-Telega, A. Milosavljevic, B. Sivaraman.

  14. Electron beam irradiation: novel technology for phytosanitary purposes

    International Nuclear Information System (INIS)

    Bhalla, Shashi; Srinivasan, K.; Dwivedi, J.; Gautam, S.; Sharma, Arun

    2015-01-01

    In the WTO regime, flow of agricultural commodities has increased, posing risk of inadvertent introduction of exotic pests. This can be minimized by undertaking quarantine measures. Quarantine/phytosanitary disinfestation treatments demand a very high level of security as the pest tolerance in quarantine is zero. Methyl bromide, a potent fumigant has been restricted in its use due to ozone depleting effect. Also, the conventional chemicals/fumigants being used world over are being restricted globally because of the various associated problems. Therefore, there is a need for an alternative ecofriendly strategy for controlling the pests. Irradiation, an approved technology by International Plant Protection Convention, appears to be a viable, nonchemical, residue-free strategy. Disinfestation of pulses with low energy electron irradiation potentially will have less deleterious effects on commodity quality than irradiation with other sources. Internationally, new radiation generating sources as Electron beam (EB) are being explored to meet import standards of quality and quarantine. The EB has a machine source and can be simply switched on or off. Irradiation of legume seeds viz., blackgram, greengram and soybean infested with pulse beetles (Callosobruchus maculatus and C. chinensis) at different doses at an energy level of 500 keV using the Accelerator facility at Raja Ramanna Centre for Advanced Technology, Indore revealed the dose-dependent effects on the insect growth parameters. Adult emergence from seeds infested with different stages was negligible and eggs laid by beetles that survived treatment did not develop into adults at higher doses. The lower doses viz., 170, 340 and 510 Gy on the other hand caused sterility effect on the insect but showed stimulatory effect on the physiological seed parameters . viz., seedling vigour and vigour index. Electron beam irradiation has a great potential for use in the disinfestation for phytosanitary purposes. Nevertheless

  15. Hydrogel coating of RVNRL film by electron beam irradiation

    International Nuclear Information System (INIS)

    Chantara Thevy Ratnam; Khairul Zaman Hj, Mohd Dahlan; Fumio Yoshii; Keizo Makuuchi

    1996-01-01

    The tackiness properties of Radiation Vulcanized Natural Rubber Latex (RVNRL) film surfaces coated by various monomers have been investigated in order to understand the suitable hydrogels which reduce the tackiness of the film. In this context , different types of monomers namely, N-vinyl-2-pyrrolidone (NVP), N,N-dimethyl amino ethyl amide (DMAEA), acrylic acid (AAc), N-butyl acrylate (n-BA) and 2-hydroxyethyl methacrylate (HEMA) as well as monomer mixtures have been tried with varying degrees of success. It was found that coating the RVNRL with 80% HEMA/20% n-BA by irradiation at 80 kGy using low Energy Electron Beam gave remarkable reduction in surface tackiness of the RVNRL film. Several other attempts were made such as priming with acid and aluminum sulfate, mixing the aluminum sulfate into the monomer and dipping the partially wet RVNRL film into the monomer to enhance the wettability of he monomers with the film. Studies on surface topography revealed that the decrease in tackiness with coating is due to the increase of the surface roughness at 80 kGy, irradiation dose

  16. A study on the effect of low energy ion beam irradiation on Au/TiO_2 system for its application in photoelectrochemical splitting of water

    International Nuclear Information System (INIS)

    Verma, Anuradha; Srivastav, Anupam; Sharma, Dipika; Banerjee, Anamika; Sharma, Shailja; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab

    2016-01-01

    Nanostructured TiO_2 thin films were deposited on indium tin oxide (ITO) substrate via sol–gel technique and were modified by plasmonic Au layer. The plasmonic Au modified TiO_2 (Au/TiO_2) thin films were then irradiated with 500 keV Ar"2"+ ion beam at different ion fluences viz. 1 × 10"1"6, 3 × 10"1"6 and 1 × 10"1"7 to study the effect of nuclear energy deposition on the morphology, crystallinity, band gap, surface plasmon resonance (SPR) peak exhibited by Au particles and photoelectrochemical properties of the system. Prepared thin films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS) measurements and UV–visible spectroscopy. The photoelectrochemical measurements revealed that both Au/TiO_2 and Au/TiO_2 thin film irradiated at 1 × 10"1"6 fluence exhibits enhanced photoelectrochemical response in comparison to pristine TiO_2. The film irradiated at 1 × 10"1"6 fluence offered maximum applied bias photon-to-current efficiency (ABPE) and shows 6 times increment in photocurrent density which was attributed to more negative flat band potential, maximum decrease in band gap, high open circuit voltage (V_o_c) and reduced charge transfer resistance.

  17. Low-energy electron scattering from CO. 2: Ab-initio study using the frame-transformation theory

    Science.gov (United States)

    Chandra, N.

    1976-01-01

    The Wigner-Eisenbud R matrix method has been combined with the frame transformation theory to study electron scattering from molecular systems. The R matrix, calculated at the boundary point of the molecular core radius, has been transformed to the space frame in order to continue the solution of the scattering equations in the outer region where rotational motion of the nuclei is taken into account. This procedure has been applied to a model calculation of thermal energy electron scattering from CO.

  18. Solution of the Eliashberg equations for a very strong electron-phonon coupling with a low-energy cutoff

    International Nuclear Information System (INIS)

    Weger, M.; Barbiellini, B.; Jarlborg, T.; Peter, M.; Santi, G.

    1995-01-01

    We solve the Eliashberg equations for the case of an explicit vector k dependence of the interactions, and of the resulting self-energies Σ 1 ( vector k,ω), Σ 2 ( vector k,ω). We consider a strong energy-dependence of the electron-electron scattering-rate τ ee -1 , which is associated with a strong energy-dependence of the electron-phonon matrix element g(k,k'). We characterize this energy-dependence by a cutoff ξ 1 , which is of the order of the phonon frequency ω ph . We find that we can account for a large number of unexpected features of the superconductivity of the cuprates by the BCS electron-phonon theory, if we consider very large values of the McMillan coupling constant λ ph , and small values of the cutoff ξ 1 . Specifically, the Coulomb interaction is found not to depress T c ; the isotope effect is strongly reduced when ξ 1 ph . We find solutions in which the gap function Δ( vector k,ω) has extended s-wave symmetry but is very anisotropic. We suggest that the underlying cause of the strong energy-dependence is a very small electronic screening parameter at the Fermi surface; the electron-phonon matrix element g is abnormally large, and this accounts for the high transition temperatures of the cuprates. An order of magnitude estimate suggests that the electron-phonon mechanism can account for transition temperatures up to about 200 K. We thus propose a very-strong-coupling theory, in which the renormalization functions, in particular the energy-renormalization X, depend very strongly on the superconducting gap Δ, and thus display a very strong temperature-dependence between T c and T=0. An experimental manifestation of the very strong coupling with a small cutoff is a zero bias anomaly sometimes observed in tunneling experiments. (orig.)

  19. Exhaust gas treatment by electron beam irradiation

    International Nuclear Information System (INIS)

    Shibamura, Yokichi; Suda, Shoichi; Kobayashi, Toshiki

    1991-01-01

    Among global environmental problems, atmospheric pollution has been discussed since relatively old days, and various countermeasures have been taken, but recently in connection with acid rain, the efficient and economical treatment technology is demanded. As the denitration and desulfurization technology for the exhaust gas from the combustion of fossil fuel, the incineration of city trash and internal combustion engines, three is the treatment method by electron beam irradiation. By irradiating electron beam to exhaust gas, nitrogen oxides and sulfur oxides are oxidized to nitric acid and sulfuric acid, and by promoting the neutralization of these acids with injected alkali, harmless salts are recovered. This method has the merit that nitrogen oxides and surfur oxides can be removed efficiently with a single system. In this report, as for the exhaust gas treatment by electron beam irradiation, its principle, features, and the present status of research and development are described, and in particular, the research on the recent exhaust gas treatment in city trash incineration is introduced. This treatment method is a dry process, accordingly, waste water disposal is unnecessary. The reaction products are utilized as fertilizer, and waste is not produced. (K.I.)

  20. Low-energy electron interaction with retusin extracted from Maackia amurensis: towards a molecular mechanism of the biological activity of flavonoids.

    Science.gov (United States)

    Pshenichnyuk, Stanislav A; Elkin, Yury N; Kulesh, Nadezda I; Lazneva, Eleonora F; Komolov, Alexei S

    2015-07-14

    The antioxidant isoflavone retusin efficiently attaches low-energy electrons in vacuo, generating fragment species via dissociative electron attachment (DEA), as has been shown by DEA spectroscopy. According to in silico results obtained by means of density functional theory, retusin is able to attach solvated electrons and could be decomposed under reductive conditions in vivo, for instance, near the mitochondrial electron transport chain, analogous to gas-phase DEA. The most intense decay channels of retusin temporary negative ions were found to be associated with the elimination of H atoms and H2 molecules. Doubly dehydrogenated fragment anions were predicted to possess a quinone structure. It is thought that molecular hydrogen, known for its selective antioxidant properties, can be efficiently generated via electron attachment to retusin in mitochondria and may be responsible for its antioxidant activity. The second abundant species, i.e., quinone bearing an excess negative charge, can serve as an electron carrier and can return the captured electron back to the respiration cycle. The number of OH substituents and their relative positions are crucial for the present molecular mechanism, which can explain the radical scavenging activity of polyphenolic compounds.