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Sample records for low-energy nitrogen implantation

  1. Nitrogen mass transfer models for plasma-based low-energy ion implantation

    SciTech Connect

    Zheng, Bocong; Wang, Kesheng; Zhang, Zhipeng; Che, Honglong; Lei, Mingkai

    2015-03-15

    The nitrogen mass transfer process in plasma-based low-energy ion implantation (PBLEII) is theoretically and experimentally studied in order to explore the process mechanism of PBLEII and therefore to optimize the apparatus design and the process conditions. An electron cyclotron resonance (ECR) microwave discharge generates the nitrogen plasma with a high density of 10{sup 11}–10{sup 12} ions/cm{sup 3}, which diffuses downstream to the process chamber along the divergent magnetic field. The nitrogen ions in the plasma implant into the surface and transport to the matrix of an austenitic stainless steel under the low negative pulsed bias of −2 kV at a process temperature of 400 °C. A global plasma model is used to simulate the ECR microwave plasma discharge for a range of working pressures and microwave powers. The fluid models are adopted to calculate the plasma downstream diffusion, the sheath expansion and the low-energy ion implantation on the surface. A nonlinear kinetic discrete model is established to describe the nitrogen transport in the austenitic stainless steel and the results are compared with the experimental measurements. Under an average implantation current density of 0.3–0.6 mA/cm{sup 2}, the surface nitrogen concentration in the range from 18.5 to 29 at. % is a critical factor for the nitrogen transport in the AISI 304 austenitic stainless steel by PBLEII, which accelerates the implanted nitrogen diffusion inward up to 6–12 μm during a nitriding time of 4 h.

  2. Enhanced nitrogen and phosphorus removal from eutrophic lake water by Ipomoea aquatica with low-energy ion implantation.

    PubMed

    Li, Miao; Wu, Yue-Jin; Yu, Zeng-Liang; Sheng, Guo-Ping; Yu, Han-Qing

    2009-03-01

    Ipomoea aquatica with low-energy N+ ion implantation was used for the removal of both nitrogen and phosphorus from the eutrophic Chaohu Lake, China. The biomass growth, nitrate reductase and peroxidase activities of the implanted I. aquatica were found to be higher than those of I. aquatica without ion implantation. Higher NO3-N and PO4-P removal efficiencies were obtained for the I. aquatica irradiation at 25 keV, 3.9 x 10(16) N+ ions/cm(2) and 20 keV 5.2 x 10(16) N+ ions/cm(2), respectively (p < 0.05). Moreover, the nitrogen and phosphorus contents in the plant biomass with ion implantation were also greater than those of the controls. I. aquatica with ion implantation was directly responsible for 51-68% N removal and 54-71% P removal in the three experiments. The results further confirm that the ion implantation could enhance the growth potential of I. aquatica in real eutrophic water and increase its nutrient removal efficiency. Thus, the low-energy ion implantation for aquatic plants could be considered as an approach for in situ phytoremediation and bioremediation of eutrophic waters.

  3. Biological effects of low energy nitrogen ion implantation on Jatropha curcas L. seed germination

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Wang, Xiao-teng; Gan, Cai-ling; Fang, Yan-qiong; Zhang, Meng

    2012-09-01

    To explore the biological effects of nitrogen ion beam implantation on dry Jatropha curcas seed, a beam of N+ with energy of 25 keV was applied to treat the dry seed at six different doses. N+ beam implantation greatly decreased germination rate and seedling survival rate. The doses within the range of 12 × 1016 to 15 × 1016 ions cm-2 severely damaged the seeds: total antioxidant capacity (TAC), germination rate, seedling survival rate, reduced ascorbate acid (HAsA) and reduced glutathione (GSH) contents, and most of the tested antioxidases activity (i.e. catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD)) reached their lowest levels. At a dose of 18 × 1016 ion cm-2, biological repair took place: moderate increases were found in TAC, germination rate, seedling survival rate, HAsA and GSH contents, and some antioxidant enzyme activities (i.e. CAT, APX, SOD and GPX). The dose of 18 × 1016 ions cm-2 may be the optimum dose for use in dry J. curcas seed mutation breeding. CAT, HAsA and GSH contributed to the increase of TAC, but CAT was the most important. POD performed its important role as seed was severely damaged. The main role of the HAsA-GSH cycle appeared to be for regeneration of HAsA.

  4. Improving low-energy boron/nitrogen ion implantation in graphene by ion bombardment at oblique angles

    NASA Astrophysics Data System (ADS)

    Bai, Zhitong; Zhang, Lin; Liu, Ling

    2016-04-01

    Ion implantation is a widely adopted approach to structurally modify graphene and tune its electrical properties for a variety of applications. Further development of the approach requires a fundamental understanding of the mechanisms that govern the ion bombardment process as well as establishment of key relationships between the controlling parameters and the dominant physics. Here, using molecular dynamics simulations with adaptive bond order calculations, we demonstrate that boron and nitrogen ion bombardment at oblique angles (particularly at 70°) can improve both the productivity and quality of perfect substitution by over 25%. We accomplished this by systematically analyzing the effects of the incident angle and ion energy in determining the probabilities of six distinct types of physics that may occur in an ion bombardment event, including reflection, absorption, substitution, single vacancy, double vacancy, and transmission. By analyzing the atomic trajectories from 576 000 simulations, we identified three single vacancy creation mechanisms and four double vacancy creation mechanisms, and quantified their probability distributions in the angle-energy space. These findings further open the door for improved control of ion implantation towards a wide range of applications of graphene.Ion implantation is a widely adopted approach to structurally modify graphene and tune its electrical properties for a variety of applications. Further development of the approach requires a fundamental understanding of the mechanisms that govern the ion bombardment process as well as establishment of key relationships between the controlling parameters and the dominant physics. Here, using molecular dynamics simulations with adaptive bond order calculations, we demonstrate that boron and nitrogen ion bombardment at oblique angles (particularly at 70°) can improve both the productivity and quality of perfect substitution by over 25%. We accomplished this by systematically

  5. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  6. Study of Biological Effects of Low Energy Ion Implantation on Tomato and Radish Breeding

    NASA Astrophysics Data System (ADS)

    Liang, Qiuxia; Huang, Qunce; Cao, Gangqiang; Ying, Fangqing; Liu, Yanbo; Huang, Wen

    2008-04-01

    Biological effects of 30 keV low energy nitrogen ion implantation on the seeds of five types of tomato and one type of radish were investigated. Results showed that low energy ions have different effects on different vegetables. The whole dose-response curve of the germination ratio did not take on "the shape of saddle", but was a rising and falling waveform with the increase or decrease in ion implantation. In the vegetable of Solanaceae, two outstanding aberrant plants were selected from M1 of Henan No.4 tomato at a dose of 7 × 1017 nitrogen ions/cm2, which had thin-leaves, long-petal and nipple tip fruit stably inherited to M7. Furthermore the analysis of the isozyme showed that the activity of the mutant tomato seedling was distinct in quantity and color. In Raphanus sativus L., the aberrances were obvious in the mutant of radish 791 at a dose of 5 × 1017 nitrogen ions/cm2, and the weight of succulent root and the volume of growth were over twice the control's. At present, many species for breeding have been identified in the field and only stable species have been selected for the experiment of production. It is evident that the low energy ion implantation technology has clear effects on vegetables' genetic improvement.

  7. Molecular ion sources for low energy semiconductor ion implantation (invited)

    NASA Astrophysics Data System (ADS)

    Hershcovitch, A.; Gushenets, V. I.; Seleznev, D. N.; Bugaev, A. S.; Dugin, S.; Oks, E. M.; Kulevoy, T. V.; Alexeyenko, O.; Kozlov, A.; Kropachev, G. N.; Kuibeda, R. P.; Minaev, S.; Vizir, A.; Yushkov, G. Yu.

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4+ ion beams were extracted. Results from devices and some additional concepts are described.

  8. Molecular ion sources for low energy semiconductor ion implantation (invited).

    PubMed

    Hershcovitch, A; Gushenets, V I; Seleznev, D N; Bugaev, A S; Dugin, S; Oks, E M; Kulevoy, T V; Alexeyenko, O; Kozlov, A; Kropachev, G N; Kuibeda, R P; Minaev, S; Vizir, A; Yushkov, G Yu

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4(+) ion beams were extracted. Results from devices and some additional concepts are described.

  9. Damaging Effect of Low Energy N+ Implantation on Aspergillus niger Spores

    NASA Astrophysics Data System (ADS)

    Wang, Lisheng; Cai, Kezhou; Cheng, Maoji; Chen, Lijuan; Liu, Xuelan; Zhang, Shuqing; Yu, Zengliang

    2007-06-01

    The mutant effects of a keV range nitrogen ion (N+) beam on enzyme-producing probiotics were studied, particularly with regard to the induction in the genome. The electron spin resonance (ESR) results showed that the signal of ESR spectrum existed in both implanted and non-implanted spores, and the yields of free radicals increased in a dose-dependent manner. The ionic etching and dilapidation of cell wall could be observed distinctly through the scanning electron microscope (SEM). The mutagenic effect on genome indicated that N+ implantation could make base mutation. This study provided an insight into the roles low-energy ions might play in inducing mutagenesis of micro-organisms.

  10. Low-energy ion implantation: Large mass fractionation of argon

    NASA Technical Reports Server (NTRS)

    Ponganis, K. V.; Graf, TH.; Marti, K.

    1993-01-01

    The isotropic signatures of noble gases in the atmospheres of the Earth and other planets are considerably evolved when compared to signatures observed in the solar wind. The mechanisms driving the evolution of planetary volatiles from original compositions in the solar accretion disk are currently poorly understood. Modeling of noble-gas compositional histories requires knowledge of fractionating processes that may have operated through the evolutionary stages. Since these gases are chemically inert, information on noble-gas fractionation processes can be used as probes. The importance of understanding these processes extends well beyond 'noble-gas planetology.' Trapped argon acquired by low-energy implantation (approximately less than 100 eV) into solids is strongly mass fractionated (approximately greater than or equal to 3 percent/amu). This has potential implications for the origin and evolution of terrestrial planet atmospheres.

  11. Effect of low-energy hydrogen ion implantation on dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.; Meier, D. L.; Rai-Choudhury, P.; Fonash, S. J.; Singh, R.

    1986-01-01

    The effect of a low-energy (0.4 keV), short-time (2-min), heavy-dose (10 to the 18th/sq cm) hydrogen ion implant on dendritic web silicon solar cells and material was investigated. Such an implant was observed to improve the cell open-circuit voltage and short-circuit current appreciably for a number of cells. In spite of the low implant energy, measurements of internal quantum efficiency indicate that it is the base of the cell, rather than the emitter, which benefits from the hydrogen implant. This is supported by the observation that the measured minority-carrier diffusion length in the base did not change when the emitter was removed. In some cases, a threefold increase of the base diffusion length was observed after implantation. The effects of the hydrogen implantation were not changed by a thermal stress test at 250 C for 111 h in nitrogen. It is speculated that hydrogen enters the bulk by traveling along dislocations, as proposed recently for edge-defined film-fed growth silicon ribbon.

  12. Low-energy plasma immersion ion implantation to induce DNA transfer into bacterial E. coli

    NASA Astrophysics Data System (ADS)

    Sangwijit, K.; Yu, L. D.; Sarapirom, S.; Pitakrattananukool, S.; Anuntalabhochai, S.

    2015-12-01

    Plasma immersion ion implantation (PIII) at low energy was for the first time applied as a novel biotechnology to induce DNA transfer into bacterial cells. Argon or nitrogen PIII at low bias voltages of 2.5, 5 and 10 kV and fluences ranging from 1 × 1012 to 1 × 1017 ions/cm2 treated cells of Escherichia coli (E. coli). Subsequently, DNA transfer was operated by mixing the PIII-treated cells with DNA. Successes in PIII-induced DNA transfer were demonstrated by marker gene expressions. The induction of DNA transfer was ion-energy, fluence and DNA-size dependent. The DNA transferred in the cells was confirmed functioning. Mechanisms of the PIII-induced DNA transfer were investigated and discussed in terms of the E. coli cell envelope anatomy. Compared with conventional ion-beam-induced DNA transfer, PIII-induced DNA transfer was simpler with lower cost but higher efficiency.

  13. Characterization of nitrogen species incorporated into graphite using low energy nitrogen ion sputtering.

    PubMed

    Kiuchi, Hisao; Kondo, Takahiro; Sakurai, Masataka; Guo, Donghui; Nakamura, Junji; Niwa, Hideharu; Miyawaki, Jun; Kawai, Maki; Oshima, Masaharu; Harada, Yoshihisa

    2016-01-01

    The electronic structures of nitrogen species incorporated into highly oriented pyrolytic graphite (HOPG), prepared by low energy (200 eV) nitrogen ion sputtering and subsequent annealing at 1000 K, were investigated by X-ray photoelectron spectroscopy (XPS), angle-dependent X-ray absorption spectroscopy (XAS), and Raman spectroscopy. An additional peak was observed at higher binding energy of 401.9 eV than 400.9 eV for graphitic1 N (graphitic N in the basal plane) in N 1s XPS, where graphitic2 N (graphitic N in the zigzag edge and/or vacancy sites) has been theoretically expected to appear. N 1s XPS showed that graphitic1 N and graphitic2 N were preferably incorporated under low nitrogen content doping conditions (8 × 10(13) ions cm(-2)), while pyridinic N and graphitic1 N were dominantly observed under high nitrogen content doping conditions. In addition, angle-dependent N 1s XAS showed that the graphitic N and pyridinic N atoms were incorporated into the basal plane of HOPG and thus were highly oriented. Furthermore, Raman spectroscopy revealed that low energy sputtering resulted in almost no fraction of the disturbed graphite surface layers under the lowest nitrogen doping condition. The suitable nitrogen doping condition was discovered for realizing the well-controlled nitrogen doped HOPG. The electrochemical properties for the oxygen reduction reaction of these samples in acidic solution were examined and discussed.

  14. Study on the Growth and the Photosynthetic Characteristics of Low Energy C+ Ion Implantation on Peanut

    PubMed Central

    Han, Yuguo; Xu, Lei; Yang, Peiling; Ren, Shumei

    2013-01-01

    Employing the Nonghua 5 peanut as experimental material, the effects of low energy C+ ion implantation on caulis height, root length, dry weight, photosynthetic characteristics and leaf water use efficiency (WUE) of Peanut Ml Generation were studied. Four fluences were observed in the experiment. The results showed that ion implantation harmed the peanut seeds because caulis height, root length and dry weight all were lower in the treatments than in CK, and the harm was aggravated with the increase of ion fluence. Both Pn and Tr show a saddle-shape curve due to midday depression of photosynthesis. Low fluence of low energy C+ ion implantation could increase the diurnal average Pn of peanut. The diurnal variation of Tr did not change as significantly as Pn. The light saturation point (LSP) was restrained by the ions. After low energy C+ ion implantation, WUE was enhanced. When the fluence increased to a certain level, the WUE began to decrease. PMID:23861939

  15. Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Singh, R.

    1985-01-01

    This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

  16. Use of low-energy hydrogen ion implants in high-efficiency crystalline-silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Sigh, R.; Mu, H. C.

    1986-01-01

    The use of low-energy hydrogen implants in the fabrication of high-efficiency crystalline silicon solar cells was investigated. Low-energy hydrogen implants result in hydrogen-caused effects in all three regions of a solar cell: emitter, space charge region, and base. In web, Czochralski (Cz), and floating zone (Fz) material, low-energy hydrogen implants reduced surface recombination velocity. In all three, the implants passivated the space charge region recombination centers. It was established that hydrogen implants can alter the diffusion properties of ion-implanted boron in silicon, but not ion-implated arsenic.

  17. Low Energy, Low Emissions: Sulfur Dioxide; Nitrogen Oxides, and Carbon Dioxide in Western Europe.

    ERIC Educational Resources Information Center

    Alcamo, Joseph; De Vries, Bert

    1992-01-01

    Links proposed low-energy scenarios for different Western European countries with the amount of pollutants that may result from these scenarios. Sulfur dioxide, nitrogen oxide, and carbon dioxide emissions are calculated for the 10 countries for which low-energy scenarios are available, resulting in reductions of 54%, 37%, and 40%, respectively.…

  18. Observations of nitrogen and oxygen isotopes in the low energy cosmic rays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Vidor, S. B.

    1975-01-01

    The isotopic composition of low-energy nitrogen and oxygen cosmic rays was measured with an electron/isotope spectrometer aboard the IMP-7 satellite to determine the possible source of the particles. Instrument calibration showed the standard range-energy tables to be inadequate to calculate the isotope response, and corrections were obtained. The low-energy nitrogen and oxygen cosmic rays were found to be primarily 14N and 16O. Upper limits were obtained for the abundances of the other stable nitrogen and oxygen isotopes. The nitrogen composition differs from higher energy measurements which indicate that 15N, which is thought to be secondary, is the dominant isotope.

  19. Interstitial injection in silicon after high-dose, low-energy arsenic implantation and annealing

    SciTech Connect

    Tsamis, C.; Skarlatos, D.; BenAssayag, G.; Claverie, A.; Lerch, W.; Valamontes, V.

    2005-11-14

    In this work, we investigate the interstitial injection into the silicon lattice due to high-dose, low-energy arsenic implantation. The approach consists in monitoring the diffusion of the arsenic profile as well as of the boron profile in buried {delta}-doped layers, when amounts of the as-implanted arsenic profile are removed by low-temperature wet silicon etching. The experimental results indicate that the contribution of the implantation damage to the transient enhanced diffusion of boron, and thus the interstitial injection, is not the main one. On the contrary, interstitial generation due to arsenic clustering seems to be more important for the present conditions.

  20. High yield antibiotic producing mutants of Streptomyces erythreus induced by low energy ion implantation

    NASA Astrophysics Data System (ADS)

    Yu, Chen; Zhixin, Lin; Zuyao, Zou; Feng, Zhang; Duo, Liu; Xianghuai, Liu; Jianzhong, Tang; Weimin, Zhu; Bo, Huang

    1998-05-01

    Conidia of Streptomyces erythreus, an industrial microbe, were implanted by nitrogen ions with energy of 40-60 keV and fluence from 1 × 10 11 to 5 × 10 14 ions/cm 2. The logarithm value of survival fraction had good linear relationship with the logarithm value of fluence. Some mutants with a high yield of erythromycin were induced by ion implantation. The yield increment was correlated with the implantation fluence. Compared with the mutation results induced by ultraviolet rays, mutation effects of ion implantation were obvious having higher increasing erythromycin potency and wider mutation spectrum. The spores of Bacillus subtilis were implanted by arsenic ions with energy of 100 keV. The distribution of implanted ions was measured by Rutherford Backscattering Spectrometry (RBS) and calculated in theory. The mechanism of mutation induced by ion implantation was discussed.

  1. Investigation of Mn-implanted n-Si by low-energy ion beam deposition

    NASA Astrophysics Data System (ADS)

    Liu, Lifeng; Chen, Nuofu; Song, Shulin; Yin, Zhigang; Yang, Fei; Chai, Chunlin; Yang, Shaoyan; Liu, Zhikai

    2005-01-01

    Mn ions were implanted to n-type Si(0 0 1) single crystal by low-energy ion beam deposition technique with an energy of 1000 eV and a dose of 7.5×10 17 cm -2. The samples were held at room temperature and at 300 °C during implantation. Auger electron spectroscopy depth profiles of samples indicate that the Mn ions reach deeper in the sample implanted at 300 °C than in the sample implanted at room temperature. X-ray diffraction measurements show that the structure of the sample implanted at room temperature is amorphous while that of the sample implanted at 300 °C is crystallized. There are no new phases found except silicon both in the two samples. Atomic force microscopy images of samples indicate that the sample implanted at 300 °C has island-like humps that cover the sample surface while there is no such kind of characteristic in the sample implanted at room temperature. The magnetic properties of samples were investigated by alternating gradient magnetometer (AGM). The sample implanted at 300 °C shows ferromagnetic behavior at room temperature.

  2. Modelisation of boron diffusion from ultra-low-energy implantation in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Ihaddadene-Le Coq, L.; Marcon, J.; Dush-Nicolini, A.; Masmoudi, K.; Ketata, K.

    2003-12-01

    We have investigated and modeled the boron diffusion in silicon following ultra-low-energy implantation (500 eV). It is well known that reducing implant energies is an effective way to eliminate transient enhanced diffusion due to the excess of interstitials from the implant. However, for sub-keV B implants diffusion remains enhanced. This enhancement is linked to the presence of a silicon boride layer located at the silicon surface which creates interstitials. This phenomenon is named "boron enhanced diffusion" (BED). The BED effect is of obvious interest since it counteracts the advantage obtained by reducing the ion implantation energy. For these reasons, we have investigated the diffusion of low-energy boron implanted in crystalline silicon and tested a complete simulation program, which takes into account the effect of boron precipitation and the effect of the silicon boride layer as a source of self-interstitials. Experimental results have been simulated and consistent parameters have been found to fit the data. BED effect has been studied. Model parameters extractions have been discussed.

  3. Isotopic fractionation of Kr and Xe implanted in solids at very low energies

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Hagee, Bryan E.

    1987-01-01

    Results on the implantation of Kr and Xe in W under closed system conditions at very low energies (50-500 eV) are reported. Investigation of the fraction of gas trapped as a function of time reveals the existence of competing trapping and release mechanisms, and analysis of recovered trapped gas and residual gas phases shows that both elemental and isotropic fractionation result from these mechanisms. It is determined that the mass dependence for the overall implantation process is at or near m exp 1, with heavier isotopes enriched in the implanted gas. This mass dependence is inferred to result from implantation and a combination of diffusive and gas sputtering release mechanisms. These results reaffirm the conclusion of Bernatowicz and Fahey (1986) that previously observed isotopic fractionation of Kr and Xe in carbonaceous material synthesized in electrical discharges owes its origin to low-energy ion implantation, and also suggest that this process may be relevant to incorporation of noble gases in early solar system materials. The implication of these results for noble gas mass spectrometry are discussed.

  4. Implantation of nitrogen: Effects of hydrogen and implantation energy

    NASA Technical Reports Server (NTRS)

    Sugiura, Naoji; Futagami, Tsuneji; Nagai, Siro

    1993-01-01

    To solve the question on solar nitrogen in lunar soils, i.e. variation in isotopic composition and apparently high retentivity compared with rare gases, nitrogen implantation experiments were conducted. At the Meteoritical Society Meeting in Copenhagen, the results of stepped combustion of implanted nitrogen in ilmenite and olivine were presented. The degassing behavior of nitrogen (and also Ar) was quite different from that observed in the case of lunar soils. Extraction temperatures are higher (greater than 1100 C for ilmenite and 1500 C for olivine) than that for lunar soils. Both nitrogen and Ar seem to be retained at the same efficiency. Therefore, additional experiments were conducted to make degassing behavior of nitrogen more close to that observed in the case of lunar soils.

  5. Sources and transport systems for low energy extreme of ion implantation

    SciTech Connect

    Hershcovitch, A.; Batalin, V.A.; Bugaev, A.S.; Gushenets, V.I.; Alexeyenko, O.; Gurkova, E.; Johnson, B.M.; Kolomiets, A.A.; Kropachev, G.N.; Kuibeda, R.P.; Kulevoy, T.V.; Masunov, E.S.; Oks, E.M.; Pershin, V.I.; Polozov, S.M.; Poole, H.J.; Seleznev, D.N.; Storozhenko, P.A.; Vizir, A.; Svarovski, A.Ya.; Yakushin, P.; Yushkov, G.Yu.

    2010-06-06

    For the past seven years a joint research and development effort focusing on the design of steady state, intense ion sources has been in progress with the ultimate goal being to meet the two, energy extreme range needs of mega-electron-volt and 100's of electron-volt ion implanters. However, since the last Fortier is low energy ion implantation, focus of the endeavor has shifted to low energy ion implantation. For boron cluster source development, we started with molecular ions of decaborane (B{sub 10}H{sub 14}), octadecaborane (B{sub 18}H{sub 22}), and presently our focus is on carborane (C{sub 2}B{sub 10}H{sub 12}) ions developing methods for mitigating graphite deposition. Simultaneously, we are developing a pure boron ion source (without a working gas) that can form the basis for a novel, more efficient, plasma immersion source. Our Calutron-Berna ion source was converted into a universal source capable of switching between generating molecular phosphorous P{sub 4}{sup +}, high charge state ions, as well as other types of ions. Additionally, we have developed transport systems capable of transporting a very large variety of ion species, and simulations of a novel gasless/plasmaless ion beam deceleration method were also performed.

  6. Defect diffusion during annealing of low-energy ion-implanted silicon

    SciTech Connect

    Bedrossian, P J; Caturla, M-J; Diaz de la Rubia, T

    2000-03-08

    We present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7x7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of the processes that underly the observed temperature-dependence of defect segregation, and the predictions of the simulations agree closely with the experimental observations.

  7. A Study of Mutation Breeding of High-Yielding Tryptophanase Escherichia coli by Low-Energy N+ Ion Beam Implantation

    NASA Astrophysics Data System (ADS)

    Pang, Min; Yao, Jianming; Wang, Dongmei

    2009-12-01

    Low energy ion beam has been widely applied in microbe breeding, plant breeding, gene transfer and cell modification. In this study, the Escherichia coli (E.coli) strain producing tryptophanase was irradiated by a low energy nitrogen ion beam with an energy of 10 keV at a fluence of 13 × 1014 N+/cm2 when glycerin at a 15% concentration was used as a protector. The effect on the biomass of E. coli after N+ implantation was analyzed in detail by statistic methods. The screening methods used in this study were proven to be effective. After continuous mutagenicity, a high-yield tryptophanase strain was selected and both its biomass and enzymatic activity were higher than those of the parent strain. The results of scale-up production showed that the biomass could reach wet weight 8.2 g/L and 110 g L-tryptophan could be formed in the volume of the 1l enzymatic reaction system.

  8. Plasma-assisted low energy N2 implant for Vfb tuning of Ge gate stacks

    NASA Astrophysics Data System (ADS)

    Kothari, Shraddha; Joishi, Chandan; Nejad, Hasan; Variam, Naushad; Lodha, Saurabh

    2016-08-01

    This work reports Vfb tuning of TiN/HfO2 gate stacks on Ge using low energy plasma-assisted doping with N2 without significant impact on gate capacitance and gate/channel interface trap densities. As required for multi-VT Ge p-FinFETs, controlled change in effective work function up to 180 mV from the near midgap to the near valence band edge of Ge is demonstrated by varying implant dose and energy. Unlike Si gate stacks, increased gate leakage in implanted Ge gate stacks is shown to result from traps created in the HfO2 layer during the implant and exposed to channel carriers due to a low band offset GeO2 interfacial layer (IL). Recovery of gate leakage is demonstrated by substituting GeO2 with an Al2O3 IL. Further, a simple physical model is proposed to extract the work function and oxide charge components of the change in Vfb for varying implant doses and energies.

  9. Direct synthesis of ultrathin SOI structure by extremely low-energy oxygen implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-06-01

    We performed extremely low-energy 16O+ implantation at 10 keV (Rp ˜ 25 nm) followed by annealing aiming at directly synthesizing an ultrathin Si layer separated by a buried SiO2 layer in Si(001) substrates, and then investigated feasible condition of recrystallization and stabilization of the superficial Si and the buried oxide layer by significantly low temperature annealing. The elemental compositions were analyzed by Rutherford backscattering (RBS) and secondary ion mass spectroscopy (SIMS). The crystallinity of the superficial Si layer was quantitatively confirmed by ananlyzing RBS-channeling spectra. Cross-sectional morphologies and atomic configurations were observed by transmission electron microscope (TEM). As a result, we succeeded in directly synthesizing an ultrathin single-crystalline silicon layer with ≤20 nm thick separated by a thin buried stoichiometric SiO2 layer with ≤20 nm thick formed by extremely low-energy 16O+ implantation followed by surprisingly low temperature annealing at 1050∘ C.

  10. Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

    2016-09-01

    In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

  11. A novel mechanism of ultrathin SOI synthesis by extremely low-energy hot O+ implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-08-01

    Extremely low-energy oxygen implantations at 10 keV in silicon were challengingly performed to directly synthesize ultrathin silicon-on-insulator (SOI) structure separated by a buried oxide (BOX) layer. We quantitatively investigated the optimum condition and the formation mechanism of homogeneous and continuous stoichiometric SOI/BOX structure. In this study, oxygen ions were implanted into Si(0 0 1) substrates with keeping the temperatures at 500, 800, and 1000 °C with ion-fluences from 0.5 to 2.0× {{10}17} ions cm-2. These samples were then postannealed at high temperatures from 950 to 1150 °C in Ar ambient for several hours. We found that ultrathin stoichiometric SOI/BOX structure with less than 20 nm thick was synthesized by oxygen implantation with an ion dose of 1.0× {{10}17} ions cm-2 from 500 °C to 800 °C followed by annealing at a significantly low temperature of 1050 °C for 5 h. According to the RBS-channeling analysis, the crystallinity was excellent as quality as that of the SOI structure formed by a wafer-bonding method. We found that the BOX layer was finally formed around the deeper end of the oxygen distribution in the as-implanted sample, though the depth of the BOX formation was much deeper than the projected range of oxygen and the damage peak of silicon. The formation process of the SOI/BOX structure proposed so far could not be applicable to the present conditions for ultrathin SOI/BOX synthesis by extremely low-energy implantation followed by low-temperature annealing. We thus suggested a novel mechanism of the ultrathin SOI/BOX synthesis as follows. The mechanism during the thermal treatment was demonstrated that the recrystallization of the damaged Si layers induced by ion irradiation took place from the very surface with relatively less irradiation-damages toward deeper layers with sweeping interstitial oxygen atoms, and the condensed oxygen atoms finally synthesized the stoichiometric BOX layer.

  12. A novel mechanism of ultrathin SOI synthesis by extremely low-energy hot O+ implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-08-01

    Extremely low-energy oxygen implantations at 10 keV in silicon were challengingly performed to directly synthesize ultrathin silicon-on-insulator (SOI) structure separated by a buried oxide (BOX) layer. We quantitatively investigated the optimum condition and the formation mechanism of homogeneous and continuous stoichiometric SOI/BOX structure. In this study, oxygen ions were implanted into Si(0 0 1) substrates with keeping the temperatures at 500, 800, and 1000 °C with ion-fluences from 0.5 to 2.0× {{10}17} ions cm‑2. These samples were then postannealed at high temperatures from 950 to 1150 °C in Ar ambient for several hours. We found that ultrathin stoichiometric SOI/BOX structure with less than 20 nm thick was synthesized by oxygen implantation with an ion dose of 1.0× {{10}17} ions cm‑2 from 500 °C to 800 °C followed by annealing at a significantly low temperature of 1050 °C for 5 h. According to the RBS-channeling analysis, the crystallinity was excellent as quality as that of the SOI structure formed by a wafer-bonding method. We found that the BOX layer was finally formed around the deeper end of the oxygen distribution in the as-implanted sample, though the depth of the BOX formation was much deeper than the projected range of oxygen and the damage peak of silicon. The formation process of the SOI/BOX structure proposed so far could not be applicable to the present conditions for ultrathin SOI/BOX synthesis by extremely low-energy implantation followed by low-temperature annealing. We thus suggested a novel mechanism of the ultrathin SOI/BOX synthesis as follows. The mechanism during the thermal treatment was demonstrated that the recrystallization of the damaged Si layers induced by ion irradiation took place from the very surface with relatively less irradiation-damages toward deeper layers with sweeping interstitial oxygen atoms, and the condensed oxygen atoms finally synthesized the stoichiometric BOX layer.

  13. Predicting Low Energy Dopant Implant Profiles in Semiconductors using Molecular Dynamics

    SciTech Connect

    Beardmore, K.M.; Gronbech-Jensen, N.

    1999-05-02

    The authors present a highly efficient molecular dynamics scheme for calculating dopant density profiles in group-IV alloy, and III-V zinc blende structure materials. Their scheme incorporates several necessary methods for reducing computational overhead, plus a rare event algorithm to give statistical accuracy over several orders of magnitude change in the dopant concentration. The code uses a molecular dynamics (MD) model to describe ion-target interactions. Atomic interactions are described by a combination of 'many-body' and pair specific screened Coulomb potentials. Accumulative damage is accounted for using a Kinchin-Pease type model, inelastic energy loss is represented by a Firsov expression, and electronic stopping is described by a modified Brandt-Kitagawa model which contains a single adjustable ion-target dependent parameter. Thus, the program is easily extensible beyond a given validation range, and is therefore truly predictive over a wide range of implant energies and angles. The scheme is especially suited for calculating profiles due to low energy and to situations where a predictive capability is required with the minimum of experimental validation. They give examples of using the code to calculate concentration profiles and 2D 'point response' profiles of dopants in crystalline silicon and gallium-arsenide. Here they can predict the experimental profile over five orders of magnitude for <100> and <110> channeling and for non-channeling implants at energies up to hundreds of keV.

  14. Creation of High-Yield Polyhydroxyalkanoates Engineered Strains by Low Energy Ion Implantation

    NASA Astrophysics Data System (ADS)

    Qian, Shiquan; Cheng, Ying; Zhu, Suwen; Cheng, Beijiu

    2008-12-01

    Polyhydroxyalkanoates (PHAs), as a candidate for biodegradable plastic materials, can be synthesized by numerous microorganisms. However, as its production cost is high in comparison with those of chemically synthesized plastics, a lot of research has been focused on the efficient production of PHAs using different methods. In the present study, the mutation effects of PHAs production in strain pCB4 were investigated with implantation of low energy ions. It was found that under the implantation conditions of 7.8 × 1014 N+/cm2 at 10 keV, a high-yield PHAs strain with high genetic stability was generated from many mutants. After optimizing its fermentation conditions, the biomass, PHAs concentration and PHAs content of pCBH4 reached 2.26 g/L, 1.81 g/L, and 80.08% respectively, whereas its wild type controls were about 1.24 g/L, 0.61 g/L, and 49.20%. Moreover, the main constituent of PHAs was identified as poly-3-hydroxybutyrates (PHB) in the mutant stain and the yield of this compound was increased up to 41.33% in contrast to that of 27.78% in the wild type strain.

  15. Radiation damage in urania crystals implanted with low-energy ions

    NASA Astrophysics Data System (ADS)

    Nguyen, Tien Hien; Garrido, Frédérico; Debelle, Aurélien; Mylonas, Stamatis; Nowicki, Lech; Thomé, Lionel; Bourçois, Jérôme; Moeyaert, Jérémy

    2014-05-01

    Implantations with low-energy ions (470-keV Xe and 500-keV La with corresponding ion range Rp ∼ 85 nm and range straggling ΔRp ∼ 40 nm) have been performed to investigate both radiation and chemical effects due to the incorporation of different species in UO2 (urania) crystals. The presence of defects was monitored in situ after each implantation fluence step by the RBS/C technique. Channelling data were analysed afterwards by Monte-Carlo simulations with a model of defects involving (i) randomly displaced atoms (RDA) and (ii) distorted rows, i.e. bent channels (BC). While increasing the ion fluence, the accumulation of RDA leads to a steep increase of the defect fraction in the range from 4 to 7 dpa regardless of the nature of bombarding ions followed by a saturation plateau over a large dpa range. A clear difference of 6% in the yield of saturation plateaus between irradiation with Xe and La ions was observed. Conversely, the evolutions of the fraction of BC showed a similar regular increase with increasing ion fluence for both ions. Moreover, this increase is shifted to a larger fluence in comparison to the sharp increase step of RDA. This phenomenon indicates a continuous structural modification of UO2 crystals under irradiation unseen by the measurement of RDA.

  16. Surface engineering of a Zr-based bulk metallic glass with low energy Ar- or Ca-ion implantation.

    PubMed

    Huang, Lu; Zhu, Chao; Muntele, Claudiu I; Zhang, Tao; Liaw, Peter K; He, Wei

    2015-02-01

    In the present study, low energy ion implantation was employed to engineer the surface of a Zr-based bulk metallic glass (BMG), aiming at improving the biocompatibility and imparting bioactivity to the surface. Ca- or Ar-ions were implanted at 10 or 50 keV at a fluence of 8 × 10(15)ions/cm(2) to (Zr0.55Al0.10Ni0.05Cu0.30)99Y1 (at.%) BMG. The effects of ion implantation on material properties and subsequent cellular responses were investigated. Both Ar- and Ca-ion implantations were suggested to induce atom displacements on the surfaces according to the Monte-Carlo simulation. The change of atomic environment of Zr in the surface regions as implied by the alteration in X-ray absorption measurements at Zr K-edge. X-ray photoelectron spectroscopy revealed that the ion implantation process has modified the surface chemical compositions and indicated the presence of Ca after Ca-ion implantation. The surface nanohardness has been enhanced by implantation of either ion species, with Ca-ion implantation showing more prominent effect. The BMG surfaces were altered to be more hydrophobic after ion implantation, which can be attributed to the reduced amount of hydroxyl groups on the implanted surfaces. Higher numbers of adherent cells were found on Ar- and Ca-ion implanted samples, while more pronounced cell adhesion was observed on Ca-ion implanted substrates. The low energy ion implantation resulted in concurrent modifications in atomic structure, nanohardness, surface chemistry, hydrophobicity, and cell behavior on the surface of the Zr-based BMG, which were proposed to be mutually correlated with each other. PMID:25492195

  17. Doping of Graphene by Low-Energy Ion Beam Implantation: Structural, Electronic, and Transport Properties.

    PubMed

    Willke, Philip; Amani, Julian A; Sinterhauf, Anna; Thakur, Sangeeta; Kotzott, Thomas; Druga, Thomas; Weikert, Steffen; Maiti, Kalobaran; Hofsäss, Hans; Wenderoth, Martin

    2015-08-12

    We investigate the structural, electronic, and transport properties of substitutional defects in SiC-graphene by means of scanning tunneling microscopy and magnetotransport experiments. Using ion incorporation via ultralow energy ion implantation, the influence of different ion species (boron, nitrogen, and carbon) can directly be compared. While boron and nitrogen atoms lead to an effective doping of the graphene sheet and can reduce or raise the position of the Fermi level, respectively, (12)C(+) carbon ions are used to study possible defect creation by the bombardment. For low-temperature transport, the implantation leads to an increase in resistance and a decrease in mobility in contrast to undoped samples. For undoped samples, we observe in high magnetic fields a positive magnetoresistance that changes to negative for the doped samples, especially for (11)B(+)- and (12)C(+)-ions. We conclude that the conductivity of the graphene sheet is lowered by impurity atoms and especially by lattice defects, because they result in weak localization effects at low temperatures. PMID:26120803

  18. Nitrogen ion implantation into various materials using 28 GHz electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Shin, Chang Seouk; Lee, Byoung-Seob; Choi, Seyong; Yoon, Jang-Hee; Kim, Hyun Gyu; Ok, Jung-Woo; Park, Jin Yong; Kim, Seong Jun; Bahng, Jungbae; Hong, Jonggi; Lee, Seung Wook; Won, Mi-Sook

    2016-02-01

    The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm2. The implantation chamber was designed to measure the beam properties with a diagnostic system as well as to perform ion implantation with an in situ system including a mass spectrometer. This advanced implantation system can be employed in novel applications, including the production of a variety of new materials such as metals, polymers, and ceramics and the irradiation testing and fabrication of structural and functional materials to be used in future nuclear fusion reactors. In this investigation, the first nitrogen ion implantation experiments were conducted using the new system. The 28 GHz ECRIS implanted low-energy, multi-charged nitrogen ions into copper, zinc, and cobalt substrates, and the ion implantation depth profiles were obtained. SRIM 2013 code was used to calculate the profiles under identical conditions, and the experimental and simulation results are presented and compared in this report. The depths and ranges of the ion distributions in the experimental and simulation results agree closely and demonstrate that the new system will enable the treatment of various substrates for advanced materials research.

  19. Nitrogen ion implantation into various materials using 28 GHz electron cyclotron resonance ion source.

    PubMed

    Shin, Chang Seouk; Lee, Byoung-Seob; Choi, Seyong; Yoon, Jang-Hee; Kim, Hyun Gyu; Ok, Jung-Woo; Park, Jin Yong; Kim, Seong Jun; Bahng, Jungbae; Hong, Jonggi; Lee, Seung Wook; Won, Mi-Sook

    2016-02-01

    The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm(2). The implantation chamber was designed to measure the beam properties with a diagnostic system as well as to perform ion implantation with an in situ system including a mass spectrometer. This advanced implantation system can be employed in novel applications, including the production of a variety of new materials such as metals, polymers, and ceramics and the irradiation testing and fabrication of structural and functional materials to be used in future nuclear fusion reactors. In this investigation, the first nitrogen ion implantation experiments were conducted using the new system. The 28 GHz ECRIS implanted low-energy, multi-charged nitrogen ions into copper, zinc, and cobalt substrates, and the ion implantation depth profiles were obtained. SRIM 2013 code was used to calculate the profiles under identical conditions, and the experimental and simulation results are presented and compared in this report. The depths and ranges of the ion distributions in the experimental and simulation results agree closely and demonstrate that the new system will enable the treatment of various substrates for advanced materials research.

  20. Nitrogen ion implantation into various materials using 28 GHz electron cyclotron resonance ion source.

    PubMed

    Shin, Chang Seouk; Lee, Byoung-Seob; Choi, Seyong; Yoon, Jang-Hee; Kim, Hyun Gyu; Ok, Jung-Woo; Park, Jin Yong; Kim, Seong Jun; Bahng, Jungbae; Hong, Jonggi; Lee, Seung Wook; Won, Mi-Sook

    2016-02-01

    The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm(2). The implantation chamber was designed to measure the beam properties with a diagnostic system as well as to perform ion implantation with an in situ system including a mass spectrometer. This advanced implantation system can be employed in novel applications, including the production of a variety of new materials such as metals, polymers, and ceramics and the irradiation testing and fabrication of structural and functional materials to be used in future nuclear fusion reactors. In this investigation, the first nitrogen ion implantation experiments were conducted using the new system. The 28 GHz ECRIS implanted low-energy, multi-charged nitrogen ions into copper, zinc, and cobalt substrates, and the ion implantation depth profiles were obtained. SRIM 2013 code was used to calculate the profiles under identical conditions, and the experimental and simulation results are presented and compared in this report. The depths and ranges of the ion distributions in the experimental and simulation results agree closely and demonstrate that the new system will enable the treatment of various substrates for advanced materials research. PMID:26931931

  1. Shallow nitrogen ion implantation: Evolution of chemical state and defect structure in titanium

    NASA Astrophysics Data System (ADS)

    Manojkumar, P. A.; Chirayath, V. A.; Balamurugan, A. K.; Krishna, Nanda Gopala; Ilango, S.; Kamruddin, M.; Amarendra, G.; Tyagi, A. K.; Raj, Baldev

    2016-09-01

    Evolution of chemical states and defect structure in titanium during low energy nitrogen ion implantation by Plasma Immersion Ion Implantation (PIII) process is studied. The underlying process of chemical state evolution is investigated using secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The implantation induced defect structure evolution as a function of dose is elucidated using variable energy positron annihilation Doppler broadening spectroscopy (PAS) and the results were corroborated with chemical state. Formation of 3 layers of defect state was modeled to fit PAS results.

  2. Preliminary Studies on Base Substitutions and Repair of DNA Mismatch Damage Stimulated by Low Energy N+ Ion Beam Implantation in Escherichia coli

    NASA Astrophysics Data System (ADS)

    Xie, Chuan-xiao; Guo, Jin-hua; Cheng, Bei-jiu; Yu, Zeng-liang

    2003-02-01

    Ever since the low energy N+ ion beam has been accepted that the mutation effects of ionizing radiation are attributed mainly to direct or indirect damage to DNA. Evidences based on naked DNA irradiation in support of a mutation spectrum appears to be consistent, but direct proof of such results in vivo are limited. Using mutS, dam and/or dcm defective Eschericha coli mutator strains, an preliminary experimental system on induction of in vivo mutation spectra of low energy N+ ion beam has been established in this study. It was observed that the mutation rates of rifampicin resistance induced by N+ implantation were quite high, ranging from 9.2 × 10-8 to 4.9 × 10-5 at the dosage of 5.2 × 1014 ions/cm2. Strains all had more than 90-fold higher mutation rate than its spontaneous mutation rate determined by this method. It reveals that base substitutions involve in induction of mutation of low energy nitrogen ion beam implantation. The mutation rates of mutator strains were nearly 500-fold (GM2929), 400-fold (GM5864) and 6-fold larger than that of AB1157. The GM2929 and GM5864 both lose the ability of repair DNA mismatch damage by virtue of both dam and dcm pathways defective (GM2929) or failing to assemble the repair complex (GM5864) respectively. It may explain the both strains had a similar higher mutation rate than GM124 did. It indicated that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N+ implantation. The further related research were also discussed.

  3. Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy

    NASA Astrophysics Data System (ADS)

    Cherkashin, N.; Daghbouj, N.; Darras, F.-X.; Fnaiech, M.; Claverie, A.

    2015-12-01

    We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters. This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He+, 3 keV H+), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.

  4. Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy

    SciTech Connect

    Cherkashin, N. Darras, F.-X.; Claverie, A.; Daghbouj, N.; Fnaiech, M.

    2015-12-28

    We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters. This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He{sup +}, 3 keV H{sup +}), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.

  5. Effective dopant activation by susceptor-assisted microwave annealing of low energy boron implanted and phosphorus implanted silicon

    SciTech Connect

    Zhao, Zhao; Vemuri, Rajitha N. P.; Alford, T. L.; David Theodore, N.; Lu, Wei; Lau, S. S.; Lanz, A.

    2013-12-28

    Rapid processing and reduced end-of-range diffusion result from susceptor-assisted microwave (MW) annealing, making this technique an efficient processing alternative for electrically activating dopants within ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Susceptor-assisted MW annealing, of ion-implanted Si, enables more effective dopant activation and at lower temperatures than required for rapid thermal annealing (RTA). Raman spectroscopy and ion channeling analyses are used to monitor the extent of ion implantation damage and recrystallization. The presence and behavior of extended defects are monitored by cross-section transmission electron microscopy. Phosphorus implanted Si samples experience effective electrical activation upon MW annealing. On the other hand, when boron implanted Si is MW annealed, the growth of extended defects results in reduced crystalline quality that hinders the electrical activation process. Further comparison of dopant diffusion resulting from MW annealing and rapid thermal annealing is performed using secondary ion mass spectroscopy. MW annealed ion implanted samples show less end-of-range diffusion when compared to RTA samples. In particular, MW annealed P{sup +} implanted samples achieve no visible diffusion and equivalent electrical activation at a lower temperature and with a shorter time-duration of annealing compared to RTA. In this study, the peak temperature attained during annealing does not depend on the dopant species or dose, for susceptor-assisted MW annealing of ion-implanted Si.

  6. Effective dopant activation by susceptor-assisted microwave annealing of low energy boron implanted and phosphorus implanted silicon

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; David Theodore, N.; Vemuri, Rajitha N. P.; Lu, Wei; Lau, S. S.; Lanz, A.; Alford, T. L.

    2013-12-01

    Rapid processing and reduced end-of-range diffusion result from susceptor-assisted microwave (MW) annealing, making this technique an efficient processing alternative for electrically activating dopants within ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Susceptor-assisted MW annealing, of ion-implanted Si, enables more effective dopant activation and at lower temperatures than required for rapid thermal annealing (RTA). Raman spectroscopy and ion channeling analyses are used to monitor the extent of ion implantation damage and recrystallization. The presence and behavior of extended defects are monitored by cross-section transmission electron microscopy. Phosphorus implanted Si samples experience effective electrical activation upon MW annealing. On the other hand, when boron implanted Si is MW annealed, the growth of extended defects results in reduced crystalline quality that hinders the electrical activation process. Further comparison of dopant diffusion resulting from MW annealing and rapid thermal annealing is performed using secondary ion mass spectroscopy. MW annealed ion implanted samples show less end-of-range diffusion when compared to RTA samples. In particular, MW annealed P+ implanted samples achieve no visible diffusion and equivalent electrical activation at a lower temperature and with a shorter time-duration of annealing compared to RTA. In this study, the peak temperature attained during annealing does not depend on the dopant species or dose, for susceptor-assisted MW annealing of ion-implanted Si.

  7. Multi-Effects and Mechanism of Broad Bean M1 Root-Tip Cells Implanted by Low Energy N+ Beam

    NASA Astrophysics Data System (ADS)

    Xu, Gu-feng; Gu, Yue-hua

    2001-06-01

    Broad beans were divided into six groups and implanted with N+ beam of 30 KeV, 8 × 1016/cm2 per time for various radiating times respectively. Besides the statistics of its vigor of germination, the M1 root-tip cells of these broad beans were systematically analyzed on their changes in mitotic percentage, morphology and behavior of chromosomes, along with the structure of cytoskeletons, including microtubule and intermediate filament. Based on all results of these studies, our opinions have been expressed in the report on the mechanism of low-energy N+ beams effecting on higher dicotyledons such as broad bean.

  8. Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

    NASA Astrophysics Data System (ADS)

    Abraham, J. B. S.; Aguirre, B. A.; Pacheco, J. L.; Vizkelethy, G.; Bielejec, E.

    2016-08-01

    We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. The ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantation process.

  9. Development of Linear Mode Detection for Top-down Ion Implantation of Low Energy Sb Donors

    NASA Astrophysics Data System (ADS)

    Pacheco, Jose; Singh, Meenakshi; Bielejec, Edward; Lilly, Michael; Carroll, Malcolm

    2015-03-01

    Fabrication of donor spin qubits for quantum computing applications requires deterministic control over the number of implanted donors and the spatial accuracy to within which these can be placed. We present an ion implantation and detection technique that allows us to deterministically implant a single Sb ion (donor) with a resulting volumetric distribution of <10 nm. This donor distribution is accomplished by implanting 30keV Sb into Si which yields a longitudinal straggle of <10 nm and combined with a <50 nm spot size using the Sandia NanoImplanter (nI). The ion beam induced charge signal is collected using a MOS detector that is integrated with a Si quantum dot for transport measurments. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  10. Breeding of Coenzyme Q10 Produced Strain by Low-Energy Ion Implantation and Optimization of Coenzyme Q10 Fermentation

    NASA Astrophysics Data System (ADS)

    Xu, Dejun; Zheng, Zhiming; Wang, Peng; Wang, Li; Yuan, Hang; Yu, Zengliang

    2008-12-01

    In order to increase the production efficiency of coenzyme Q10, the original strain Agrobacterium tumefaciens ATCC 4452 was mutated by means of Nitrogen ions implantation. A mutant strain, ATX 12, with high contents of coenzyme Q10 was selected. Subsequently, the conditions such as carbohydrate concentration, nitrogen source concentration, inoculum's size, seed age, aeration and temperature which might affect the production of CoQ10 were investigated in detail. Under optimal conditions, the maximum concentration of the intracellular CoQ10 reached 200.3 mg/L after 80 h fed-batch fermentation, about 245% increasing in CoQ10 production after ion implantation, compared to the original strain.

  11. Tribological performance of surfaces enhanced by texturing and nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Liu, Derong; Zhang, Qi; Qin, Zhenbo; Luo, Qin; Wu, Zhong; Liu, Lei

    2016-02-01

    In this paper, a novel texturing technology by means of electrodepositon is introduced. Textured surface covered with small bumps with the average size of 28 μm in diameter and 10 μm in height was fabricated. The trough around the bumps acts as the pocket to trap the debris. The nitrogen implantation was used to enhance the tribological properties of textured surfaces. The effects of implanted energy and dose on the structures of coating and tribological performances of textured surfaces were studied. The results show that the formation of Cr2N or CrN depends on the implanted dose. After nitrogen ion implantation, the friction coefficient of textured surface reduced and the wear resistance of textured surface was improved. The wear resistance enhances with increase of implanted dose, and has little to do with implanted energy.

  12. Study of the amorphization of surface silicon layers implanted by low-energy helium ions

    NASA Astrophysics Data System (ADS)

    Lomov, A. A.; Myakon'kikh, A. V.; Oreshko, A. P.; Shemukhin, A. A.

    2016-03-01

    The structural changes in surface layers of Si(001) substrates subjected to plasma-immersion implantation by (2-5)-keV helium ions to a dose of D = 6 × 1015-5 × 1017 cm-2 have been studied by highresolution X-ray diffraction, Rutherford backscattering, and spectral ellipsometry. It is found that the joint application of these methods makes it possible to determine the density depth distribution ρ( z) in an implanted layer, its phase state, and elemental composition. Treatment of silicon substrates in helium plasma to doses of 6 × 1016 cm-2 leads to the formation of a 20- to 30-nm-thick amorphized surface layer with a density close to the silicon density. An increase in the helium dose causes the formation of an internal porous layer.

  13. Influence of low-energy argon implantation on gallium arsenide Schottky barriers

    SciTech Connect

    Wang, Y.G.; Ashok, S.

    1989-03-15

    The influence of ion bombardment damage on the properties of Au/GaAs Schottky barriers has been studied with 10-keV Ar implanted into both n-type and p-type GaAs over the dose range 10/sup 12/--10/sup 15/ cm/sup -2/. Electrical characteristics determined over a wide temperature range (77--360 K) reveal a number of phenomena dictating barrier modification and carrier transport across the Au/GaAs interface: Change in Schottky barrier height due to defect levels introduced by ion damage, the very low threshold dose for barrier modification, increased series resistance, and creation of a shunt conducting path. Partial dynamic annealing of defects is also observed under high-temperature (approx. =200 /sup 0/C) implantation.

  14. Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

    NASA Astrophysics Data System (ADS)

    Pentecoste, Lucile; Thomann, Anne-Lise; Melhem, Amer; Caillard, Amael; Cuynet, Stéphane; Lecas, Thomas; Brault, Pascal; Desgardin, Pierre; Barthe, Marie-France

    2016-09-01

    The aim of this work is to investigate the first stages of defect formation in tungsten (W) due to the accumulation of helium (He) atoms inside the crystal lattice. To reach the required implantation conditions, i.e. low He ion fluxes (1011-1014 ions.cm2.s-1) and kinetic energies below the W atom displacement threshold (about 500 eV for He+), an ICP source has been designed and connected to a diffusion chamber. Implantation conditions have been characterized by means of complementary diagnostics modified for measurements in this very low density helium plasma. It was shown that lowest ion fluxes could only be reached for the discharge working in capacitive mode either in α or γ regime. Special attention was paid to control the energy gained by the ions by acceleration through the sheath at the direct current biased substrate. At very low helium pressure, in α regime, a broad ion energy distribution function was evidenced, whereas a peak centered on the potential difference between the plasma and the biased substrate was found at higher pressures in the γ mode. Polycrystalline tungsten samples were exposed to the helium plasma in both regimes of the discharge and characterized by positron annihilation spectroscopy in order to detect the formed vacancy defects. It was found that W vacancies are able to be formed just by helium accumulation and that the same final implanted state is reached, whatever the operating mode of the capacitive discharge.

  15. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NASA Astrophysics Data System (ADS)

    Dobrovolskiy, S.; Yakshin, A. E.; Tichelaar, F. D.; Verhoeven, J.; Louis, E.; Bijkerk, F.

    2010-03-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10-20 nm were produced by sequential deposition of Si and implantation of 1 keV CHx+ ions. Only about 3% of the implanted carbon was transferred into the SiC, with a thin, 0.5-1 nm, buried SiC layer being formed. We investigated the effect of thermal annealing on further completion of the carbide layer. For the annealing we used a vacuum furnace, a rapid thermal annealing system in argon atmosphere, and a scanning e-beam, for different temperatures, heating rates, and annealing durations. Annealing to a temperature as low as 600 °C resulted in the formation of a 4.5 nm smooth, amorphous carbide layer in the carbon-implanted region. However, annealing at a higher temperature, 1000 °C, lead to the formation of a rough poly-crystalline carbide layer. The multilayers were characterized by grazing incidence X-ray reflectometry and cross section TEM.

  16. Electrical properties of metal-oxide-semiconductor structures with low-energy Ge-implanted and annealed thin gate oxides

    NASA Astrophysics Data System (ADS)

    Kapetanakis, E.; Normand, P.; Holliger, P.

    2008-03-01

    The electrical characteristics of low-energy (3keV) Ge-implanted and, subsequently, thermal annealed SiO2 layers are investigated through capacitance-voltage (C-V ) and conductance-voltage (G-V) measurements of metal-oxide-semiconductor capacitors. Particular emphasis is placed on the properties of such gate oxides for memory applications. Capacitance measurements at flatband voltage before and after the application of constant voltage stress in the accumulation regime indicate that the charge trapping behavior of the devices undergoes a major change after annealing at temperatures higher than 910°C. The latter change is identified as a relocation of Ge atoms mainly toward the upper portion of the oxide with a significant fraction of them leaving the oxide; a finding in harmony with secondary ion mass spectroscopy analysis. The interface trap density (Dit) for the thin (9-12nm) implanted oxides decreases with increasing annealing temperature, approaching at 950°C the Dit levels in the mid-1010eV-1cm-2 range of the nonimplanted samples. At elevated annealing temperatures (>1000°C), the device C-V characteristics are substantially disturbed. In this case, the presence of electrically active Ge atoms at an extended depth in the substrate modifies the intrinsic electrical properties of the n-Si substrate, lending a p-type conductivity character to the device high-frequency C-V curves. Substrate electrical modification is interpreted through a model that takes into account the formation of a SiO2/Ge-rich-Si /n-Si system. The SiO2/Ge-rich-Si interface presents very low Dit levels as revealed by conductance loss characteristics. The present study suggests that a combination of Ge implantation into SiO2 films and thermal annealing may be exploited in damage-free SiGe epitaxial growth technology based on Ge implantation.

  17. Fabrication of surface magnetic nanoclusters using low energy ion implantation and electron beam annealing

    NASA Astrophysics Data System (ADS)

    Kennedy, J.; Leveneur, J.; Williams, G. V. M.; Mitchell, D. R. G.; Markwitz, A.

    2011-03-01

    Magnetic nanoclusters have novel applications as magnetic sensors, spintronic and biomedical devices, as well as applications in more traditional materials such as high-density magnetic storage media and high performance permanent magnets. We describe a new synthesis protocol which combines the advantages of ion implantation and electron beam annealing (EBA) to produce surface iron nanoclusters. We compare the structure, composition and magnetic properties of iron nanoclusters fabricated by low dose 15 keV Fe implantation into SiO2 followed by 1000 °C EBA or furnace annealing. Atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) images together with superconducting quantum interference device (SQUID) magnetometry measurements show that only EBA leads to the rapid formation of surface crystalline Fe spherical nanoclusters, showing magnetic moments per Fe atom comparable to that of bulk bcc Fe and superparamagnetic properties. We propose a fabrication mechanism which includes e-beam enhanced desorption of SiO2. This method has potential for fabricating nanoscale magnetic sensors integrated in microelectronic devices.

  18. High temperature annealing effects on low energy iron implanted SiO 2

    NASA Astrophysics Data System (ADS)

    Kennedy, J.; Leveneur, J.; Markwitz, A.

    2012-02-01

    15 keV Fe ions were implanted into a thermally grown silica film with a fluence of 1 × 10 16 at./cm 2 resulting in a near Gaussian concentration profile peaking at 8 at.% about 15 nm under the surface. High vacuum (˜10 -7 mbar) furnace annealing and electron beam annealing at high temperature resulted in diffusion of Fe inside the oxide film. Segregation of Fe atoms at the SiO 2 surface and SiO 2/Si interface was observed in both cases. EBA resulted in faster precipitation and lower out-diffusion of Fe. In-situ Rutherford Backscattering Spectrometry was performed during high vacuum annealing and is shown to be an appropriate method to investigate the diffusion rate. The differences observed between the methods are explained by the effect of excess electrons and ionization induced by the electron beam on the oxygen-vacancy mediated displacement mechanism and on the reduction of Fe oxides.

  19. Pitting behavior of aluminum ion implanted with nitrogen

    SciTech Connect

    McCafferty, E.; Natishan, P.M.; Hubler, G.K.

    1997-07-01

    Ion implantation of {approx} 2 at% N into aluminum increased the pitting potential in 0.1 M sodium chloride by an average of 0.35 V. Surface analysis by x-ray photoelectron spectroscopy showed implanted nitrogen was present as several species: NH{sub 4}{sup +}, NO or NH{sub 3} (as a ligand), AIN, and weakly bound or interstitial nitrogen. With anodic polarization, there was an increase in the total amount of nitrogen in the near-surface region, a decrease in the relative amount of nitride, and an increase in the relative amount of NO or NH{sub 3}. These changes resulted from migration of implanted nitrogen from the substrate into the near-surface region with partial conversion of the AIN species to NO or NH{sub 3}. It was suggested that the effect of implanted nitrogen on pitting behavior of aluminum is similar to that in nitrogen-containing stainless steels, where nitrogen at the metal surface inhibits the dissolution kinetics or aids the repassivation process in the pit by forming NH{sub 4}{sup +} ions that buffer the pit electrolyte.

  20. Surface microanalytical studies of nitrogen ion-implanted steel

    NASA Astrophysics Data System (ADS)

    Dodd, Charles G.; Meeker, G. P.; Baumann, Scott M.; Norberg, James C.; Legg, Keith O.

    1985-03-01

    Five types of industrial steels, 1018, 52100, M-2, 440C, and 304 were ion implanted with nitrogen and subjected to surface microanalysis by three independent surface techniques: AES, RBS, and SIMS. The results provided understanding for earlier observations of the properties of various types of steel after nitrogen implantation. The steels that retained the most nitrogen and that have been reported to benefit the most in improved tribological properties from ion implantation were ferritic carbon and austenitic stainless steels, such as soft 1018 and 304, respectively. Heat-treated martensitic carbon steels such as 52100 and M-2 tool steel were found to retain the least nitrogen, and they have been reported to benefit less from nitrogen implantation; however, the interaction of transition metal carbides in M-2 with nitrogen has not been clarified. The data showed that 440C steel retained as much nitrogen as 1018 and 304, but treatment benefits may be limited to improvements in properties related to toughness and impact resistance.

  1. Soft X-Ray Emission in the Water Window Region with Nitrogen Filling in a Low Energy Plasma Focus

    NASA Astrophysics Data System (ADS)

    Akel, M.; Lee, S.

    2013-02-01

    For operation of the plasma focus in nitrogen, a focus pinch compression temperature range of 74-173 eV (0.86 × 106-2 × 106 K) is found to be suitable for good yield of nitrogen soft X-rays in the water window region. Using this temperature window, numerical experiments using five phase Lee model have been investigated on UNU/ICTP PFF and APF plasma focus devices with nitrogen filling gas. The Lee model was applied to characterize and optimize these two plasma focus devices. The optimum nitrogen soft X-ray yield was found to be Ysxr = 2.73 J, with the corresponding efficiency of 0.13 % for UNU/ICTP PFF device, while for APF device it was Ysxr = 4.84 J, with the corresponding efficiency of 0.19 % without changing the capacitor bank, merely by changing the electrode configuration and operating pressure. The Lee model code was also used to run numerical experiments for optimizing soft X-ray yield with reducing L0, varying z0 and `a'. From these numerical experiments we expect to increase the nitrogen soft X-ray yield of low energy plasma focus devices to maximum value of near 8 J, with the corresponding efficiency of 0.4 %, at an achievable L0 = 10 nH.

  2. Elastic properties of sub-stoichiometric nitrogen ion implanted silicon

    NASA Astrophysics Data System (ADS)

    Sarmanova, M. F.; Karl, H.; Mändl, S.; Hirsch, D.; Mayr, S. G.; Rauschenbach, B.

    2015-04-01

    Elastic properties of sub-stoichiometric nitrogen implanted silicon were measured with nanometer-resolution using contact resonance atomic force microscopy (CR-AFM) as function of ion fluence and post-annealing conditions. The determined range of indentation moduli was between 100 and 180 GPa depending on the annealing duration and nitrogen content. The high indentation moduli can be explained by formation of Si-N bonds, as verified by X-ray photoelectron spectroscopy.

  3. Concentration dependent nitrogen diffusion coefficient in expanded austenite formed by ion implantation

    NASA Astrophysics Data System (ADS)

    Mandl, S.; Rauschenbach, B.

    2002-06-01

    Expanded austenite, formed after nitrogen plasma immersion ion implantation or low energy nitriding of austenitic stainless, is characterized by a high nitrogen content CN of up to 20 at. % and an unusual fast diffusion, which in general cannot be described using a single diffusion coefficient. Here, the concentration dependent diffusivity is calculated for several experimental parameters and steel alloys. Two mathematical simplifications of the general diffusion theory, well justified for physical reasons, helped in solving the equations. First, a constant surface concentration was assumed, despite a constant nitrogen flux into the surface, and, second, only mobile nitrogen atoms in a stationary steel matrix were considered. Thus, it was possible to solve the Boltzmann-Matano equation and obtain the concentration dependent diffusion coefficient D(CN). In all cases, a step-like behavior, with a high value for high nitrogen contents and a low value for low ones, is found, with the transition point between a nitrogen concentration of 5 and 17 at. %, depending on the sample.

  4. Sub-2y node NAND flash characteristics using spot beam technology for low energy, high tilt implant for n-poly doping

    NASA Astrophysics Data System (ADS)

    Ryu, Chong-Il; Lee, Sangsun; Jeon, Young-Ho; Cheon, Youngil; Choi, Jin-Kwan; Yang, Young-Ho; Lee, Kyung-Won; Hong, Rympyo; Yoon, Jong-Yoon; Reece, Ron; Rubin, Leonard M.

    2012-11-01

    Reduction of polysilicon sheet resistivity and polysilicon depletion ratio (PDR) are two major challenges for improving the memory cell characteristics of sub-20 nm NAND Flash devices. High phosphorus doses are implanted into in situ doped polysilicon floating gates to improve PDR, but phosphorus concentrations that are too high can degrade cell characteristics by increasing trapped charge in the TNOX(Tunnel Oxide). It is also important to prevent the bending of narrow polysilicon lines during floating gate implantation. We explored various conditions of low energy, high tilt phosphorus implants for floating gate doping using a spot beam high current implanter. The optimal concentration of implant energy, tilt angle, and thermal annealing has been shown to improve PDR and floating gate TOP CD control.

  5. Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

    2005-01-01

    A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of

  6. Spatial distribution of fluorescent light emitted from neon and nitrogen excited by low energy electron beams

    SciTech Connect

    Morozov, A.; Kruecken, R.; Ulrich, A.; Wieser, J.

    2006-11-01

    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.

  7. The damaging effects of nitrogen ion beam implantation on upland cotton ( Gossypium hirsutum L.) pollen grains

    NASA Astrophysics Data System (ADS)

    Yu, Yanjie; Wu, Lijun; Wu, Yuejin; Wang, Qingya; Tang, Canming

    2008-09-01

    With the aim to study the effects of an ion beam on plant cells, upland cotton (Gossypium hirsutum L.) cultivar "Sumian 22" pollen grains were irradiated in vacuum (7.8 × 10-3 Pa) by low-energy nitrogen ions with an energy of 20 keV at various fluences ranging from 0.26 × 1016 to 0.78 × 1016 N+/cm2. The irradiation effects on pollen grains were tested, considering the ultrastructural changes in the exine and interior walls of pollen grains, their germination rate, the growth speed of the pollen tubes in the style, fertilization and boll development after the pistils were pollinated by the pollen grains which had been implanted with nitrogen ions. Nitrogen ions entered the pollen grains by etching and penetrating the exine and interior walls and destroying cell structures. A greater percentage of the pollen grains were destroyed as the fluence of N+ ions increased. Obviously, the nitrogen ion beam penetrated the exine and interior walls of the pollen grains and produced holes of different sizes. As the ion fluence increased, the amount and the density of pollen grain inclusions decreased and the size of the lacuna and starch granules increased. Pollen grain germination rates decreased with increasing ion fluence. The number of pollen tubes in the style declined with increased ion implantation into pollen grains, but the growth speed of the tubes did not change. All of the pollen tubes reached the end of the style at 13 h after pollination. This result was consistent with that of the control. Also, the weight and the diameter of the ovary decreased and shortened with increased ion beam implantation fluence. No evident change in the fecundation time of the ovule was observed. These results indicate that nitrogen ions can enter pollen grains and cause a series of biological changes in pollen grains of upland cotton.

  8. Sub-5 nm graphene nanopore fabrication by nitrogen ion etching induced by a low-energy electron beam

    NASA Astrophysics Data System (ADS)

    Fox, Daniel S.; Maguire, Pierce; Zhou, Yangbo; Rodenburg, Cornelia; O’Neill, Arlene; Coleman, Jonathan N.; Zhang, Hongzhou

    2016-05-01

    A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species.

  9. Sub-5 nm graphene nanopore fabrication by nitrogen ion etching induced by a low-energy electron beam.

    PubMed

    Fox, Daniel S; Maguire, Pierce; Zhou, Yangbo; Rodenburg, Cornelia; O'Neill, Arlene; Coleman, Jonathan N; Zhang, Hongzhou

    2016-05-13

    A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species.

  10. Impact of the end of range damage from low energy Ge preamorphizing implants on the thermal stability of shallow boron profiles

    SciTech Connect

    Camillo-Castillo, R.A.; Law, M.E.; Jones, K.S.

    2004-11-01

    A fundamental understanding of the effect of scaling amorphous layers on the thermal stability of active concentrations is required for the formation of ultrashallow junctions. A study on the influence of boron on the evolution of the end of range defects for samples containing shallow amorphous layers formed by low energy germanium implants is conducted. Czochralski grown (100) silicon wafers are preamorphized with 1x10{sup 15} cm{sup -2}, 10 keV Ge{sup +} and subsequently implanted with 1x10{sup 15} cm{sup -2}, 1 keV B{sup +} such that high boron levels are attained in the end of range region. A sequence of anneals are performed at 750 deg. C, under nitrogen ambient for times ranging from 1 s to 6 h and the end of range defect evolution is imaged via plan-view transmission electron microscopy (TEM). Defect analyses are conducted utilizing quantitative TEM which indicates substantial differences in the defect evolution for samples with boron in the end of range. The extended defects observed are very unstable and undergo a fast dissolution. In contrast, stable defects are observed in the experimental control in which the evolution follows an Ostwald ripening behavior. Secondary ion mass spectroscopy analyses confirm the ephemeral nature of the defects observed and also demonstrates drastic reductions in interstitial supersaturation. In addition, uphill-type diffusion is observed to occur for a short time frame, which emphasizes a transient interstitial supersaturation. Correlation of this data with sheet resistance and active dose measurements conducted on a Hall measurement system strongly indicates the formation of boron interstitial clusters. The high boron concentrations and supersaturation levels attained at the anneal temperature enables the cluster formation. An estimate of the boron concentrations trapped in the clusters is determined from the active dose obtained from the Hall measurements and indicates concentrations much higher than those available in

  11. Annealing Behavior of Ion-implanted Nitrogen in D9 Steel

    SciTech Connect

    Arunkumar, J.; David, C.; Nair, K. G. M.; Panigrahi, B. K.; Magudapathy, P.; Kennedy, John

    2011-07-15

    Nitrogen isotope N{sup 15} was implanted at the sub-surface of D9 steel. The resonance nuclear reaction analysis was used to probe the implanted nitrogen as a function of depth. The as-implanted D9 sample was isochronally annealed and by observing the broadening of nitrogen depth profile at various annealing junctures, activation energy for nitrogen diffusion in steel was deduced.

  12. FeN foils by nitrogen ion-implantation

    SciTech Connect

    Jiang, Yanfeng; Wang, Jian-Ping; Al Mehedi, Md; Fu, Engang; Wang, Yongqiang

    2014-05-07

    Iron nitride samples in foil shape (free standing, 500 nm in thickness) were prepared by a nitrogen ion-implantation method. To facilitate phase transformation, the samples were bonded on the substrate followed by a post-annealing step. By using two different substrates, single crystal Si and GaAs, structural and magnetic properties of iron nitride foil samples prepared with different nitrogen ion fluences were characterized. α″-Fe{sub 16}N{sub 2} phase in iron nitride foil samples was obtained and confirmed by the proposed approach. A hard magnetic property with coercivity up to 780 Oe was achieved for the FeN foil samples bonded on Si substrate. The feasibility of using nitrogen ion implantation techniques to prepare FeN foil samples up to 500 nm thickness with a stable martensitic phase under high ion fluences has been demonstrated. A possible mechanism was proposed to explain this result. This proposed method could potentially be an alternative route to prepare rare-earth-free FeN bulk magnets by stacking and pressing multiple free-standing thick α″-Fe{sub 16}N{sub 2} foils together.

  13. Enhanced surface hardness in nitrogen-implanted silicon carbide

    SciTech Connect

    Uslu, C.; Lee, D.H.; Berta, Y.

    1995-06-01

    Preliminary studies have been performed on the feasibility of carbon-silicon nitride formation ({beta}-Si{sub 1.5}C{sub 1.5}N{sub 4}, the homologue of equilibrium {beta}-Si{sub 3}N{sub 4} or hypothetical {beta}-C{sub 3}N{sub 4}) by high dose N{sup +}-implantation into polycrystalline {beta}-SiC (cubic). Thin films were formed using 100 keV implantations with varying ion doses in the range from 1.1 x 10{sup 17} to 27.1 x 10{sup 17} N/cm{sup 2}, and target temperatures between -196{degrees}C and 980{degrees}C. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces (up to 860{degrees}C) contained {approximately}0.1 {mu}m thick buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting formation of a new phase. Implantation to doses of 1.1 x 10{sup 17} and 2.3 x 10{sup 17} N/cm{sup 2} at 980{degrees}C caused enhanced surface hardness compared to SiC.

  14. Effect of low-energy laser (He-Ne) irradiation on embryo implantation rate in the rat

    NASA Astrophysics Data System (ADS)

    Stein, Anat; Kraicer, P. F.; Oron, Uri

    1997-12-01

    Attempts to date to increase the rate of embryo implantation, for example by assisting embryo hatching from the zona pellucida, have failed. Recently, several studies have suggested the biostimulating effect of low power laser irradiation. The objective of this study was therefore to examine the potential of low power laser irradiation of the uterus to enhance embryo implantation rate in the rat. Rat potential of low power laser irradiation of the uterus to enhance embryo implantation rate in the rat. Rat blastocysts were flushed from the uterus on day 5 of gestation. They were transferred to the uteri of pseudopregnant recipients on day 4 or 5 of pseudopregnancy. One cornu of the recipient uterus was irradiated; the other was used as control. On day 5 of pregnancy, irradiation did not change implantation rate after 10 or 30 sec of irradiation while 120 sec. of irradiation significantly decreased embryonic implantation. On the other hand, on day 4 of pregnancy, 120 sec. of radiation allowed embryonic implantation to a level similar to that seen after synchronized transfer. Conclusion: He-Ne laser irradiation of the exposed rat uterus can attenuate embryo implantation rate.

  15. Titanium and zirconium based alloys modified by intensive plastic deformation and nitrogen ion implantation for biocompatible implants.

    PubMed

    Byeli, A V; Kukareko, V A; Kononov, A G

    2012-02-01

    Titanium and zirconium alloys are considered to be promising materials for orthopaedics because of their biocompatibility with tissues. Their main drawbacks for application as implants have generally been considered to be insufficient levels of mechanical and tribological properties. In this research the influence of equal channel angular pressing and nitrogen ion implantation on the structure and properties of Ti and Zr alloys has been investigated to ensure the optimum combination of the bulk material and surface layer properties. The data obtained showed that equal channel angular pressing and nitrogen ion implantation can be efficiently used to improve bulk and surface properties of Ti and Zr based implants.

  16. SEMICONDUCTOR TECHNOLOGY: Influence of nitrogen dose on the charge density of nitrogen-implanted buried oxide in SOI wafers

    NASA Astrophysics Data System (ADS)

    Zhongshan, Zheng; Zhongli, Liu; Ning, Li; Guohua, Li; Enxia, Zhang

    2010-02-01

    To harden silicon-on-insulator (SOI) wafers fabricated using separation by implanted oxygen (SIMOX) to total-dose irradiation, the technique of nitrogen implantation into the buried oxide (BOX) layer of SIMOX wafers can be used. However, in this work, it has been found that all the nitrogen-implanted BOX layers reveal greater initial positive charge densities, which increased with increasing nitrogen implantation dose. Also, the results indicate that excessively large nitrogen implantation dose reduced the radiation tolerance of BOX for its high initial positive charge density. The bigger initial positive charge densities can be ascribed to the accumulation of implanted nitrogen near the Si-BOX interface after annealing. On the other hand, in our work, it has also been observed that, unlike nitrogen-implanted BOX, all the fluorine-implanted BOX layers show a negative charge density. To obtain the initial charge densities of the BOX layers, the tested samples were fabricated with a metal-BOX-silicon (MBS) structure based on SIMOX wafers for high-frequency capacitance-voltage (C-V) analysis.

  17. Properties of nitrogen implanted and electron beam annealed bulk ZnO

    SciTech Connect

    Kennedy, J.; Carder, D. A.; Markwitz, A.; Reeves, R. J.

    2010-05-15

    The optical properties of bulk ZnO ion implanted with nitrogen ions, at an energy of 23 keV have been studied as a function of implantation fluence and electron beam (EB) annealing conditions. Nuclear reaction analysis and Raman results have revealed the implanted N concentration and its structural changes with respect to various nitrogen ion fluences. The optical properties of nitrogen implanted bulk ZnO were investigated by low temperature photoluminescence measurements. An enhanced peak at 3.235 eV has been attributed to donor-accepter pair (DAP) emission involving the implanted N acceptor in ZnO. The emission near 3.3085 eV is attributed to a free electron to acceptor transition. We also report a broad band emission feature at {approx}3.09 eV in the nitrogen implanted with 1-2x10{sup 15} ions cm{sup -2} and EB annealed at 800-900 deg. C. This is assigned to a thermally activated nitrogen acceptor transition as it is unique only to nitrogen implanted samples. An ionization energy of 377 meV indicates that this line may correspond to a significantly less shallow acceptor level. In addition an increase in the intensity and dominance of this DAP line in nitrogen implanted samples over the other acceptor transitions was observed with increasing annealing time and temperatures. It is shown that EB annealing offers a method of enhanced nitrogen activation when compared to a more conventional furnace approach.

  18. Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

    DOE PAGESBeta

    Abraham, John Bishoy Sam; Pacheco, Jose L.; Aguirre, Brandon Adrian; Vizkelethy, Gyorgy; Bielejec, Edward S.

    2016-08-09

    We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. In conclusion, the ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantationmore » process.« less

  19. Ozone and carbon trioxide synthesis by low energy ion implantation onto solid carbon dioxide and implications to astrochemistry

    NASA Astrophysics Data System (ADS)

    Sivaraman, Bhalamurugan; Raja Sekhar, B. N.; Fulvio, Daniele; Hunniford, Adam; McCullough, Bob; Palumbo, Maria Elisabetta; Mason, Nigel

    2013-08-01

    Ion implantation experiments were carried out on amorphous (30 K) and crystalline (80 K) solid CO2 using both reactive (D+, H+) and non-reactive (He+) ions, simulating different irradiation environments on satellite and dust grain surfaces. Such ion irradiation synthesized several new species in the ice including ozone (O3), carbon trioxide (CO3), and carbon monoxide (CO) the main dissociation product of carbon dioxide. The yield of these products was found to be strongly dependent upon the ion used for irradiation and the sample temperature. Ion implantation changes the chemical composition of the ice with recorded infrared spectra clearly showing the coexistence of D3h and C2v isomers of CO3, for the first time, in ion irradiated CO2 ice.

  20. A MedRadio-band low-energy-per-bit 4-Mbps CMOS OOK receiver for implantable medical devices.

    PubMed

    Chou, Chia-Wei; Liu, Li-Chen; Wu, Chung-Yu

    2013-01-01

    A 4-Mbps 400-MHz On-Off Keying (OOK) receiver implemented in 0.18-um CMOS technology for implantable epilepsy sense-and-stimulation devices is presented. The proposed receiver is composed of a new current-mode full-wave envelope detector and differential cascaded gain amplifiers which is operated at MedRadio band. The fabricated receiver has power consumption of 0.27 mW and energy consumption of 0.07 nJ per bit at 4-Mbps. The sensitivity of receiver is -45.67 dBm.

  1. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    PubMed

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly. PMID:26789206

  2. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    PubMed

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.

  3. Nitrogen Doping of Single-Walled Carbon Nanotube by Using Mass-Separated Low-Energy Ion Beams

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuhiro; Kamimura, Takafumi; Matsumoto, Kazuhiko

    2005-04-01

    Mass-separated nitrogen ions with the mass number of 14 were irradiated to the single-walled carbon nanotubes (SWCNTs) under an ultra high-vacuum pressure of 10-7 Pa for the purpose of achieving nitrogen doping in nanotubes. The incident angle of the ion beam was normal to the target nanotube, and the ion beam energy was 30 eV, which was close to the displacement energy of graphite. The dependence of the structure of SWCNTs on the ion dose was investigated. The ion dose ranged from 2.8× 1014 to 2.2× 1016 ions/cm2. The nitrogen ions are incorporated into graphite sheets of SWCNTs after irradiation at 2.8× 1014 ions/cm2. The graphite structure is distorted and many defects are induced in the nanotube by the nitrogen incorporation. The structure is changed to amorphous after irradiation at 2.2× 1016 ions/cm2. The nitrogen ions with the ion energy of 25 eV are irradiated to the field effect transistor device with the nanotube channel. The n-type characteristic appears upon ion irradiation, and the device exhibits ambipolar behavior.

  4. Effect of MeV nitrogen ion implantation on the resistivity transition in Czochralski silicon wafers

    NASA Astrophysics Data System (ADS)

    Moon, Byeong-Sam; Lee, In-Ji; Park, Jea-Gun

    2012-12-01

    We investigated how MeV nitrogen ion implantation affects the resistivity transition in Czochralski (CZ) silicon wafers. After annealing at 800 °C for 20 h and again at 1000 °C for 10 h, the implanted nitrogen atoms accumulated in the projected range (R P ) for ion doses less than 5 × 1014 cm-2 whereas they accumulated at both R P /2 and R P at ion doses above 3 × 1015 cm-2. These results indicate that no resistivity transition was found at nitrogen ion doses less than 5 × 1013 cm-2 whereas n-/p or n+/p resistivity transition was shown at ion doses higher than 5 × 1014 cm-2. Many fewer than 1% of the implanted nitrogen atoms were ionized after the heat treatment. Thus, the resistivity of nitrogen-doped silicon wafers is more than 100 times higher than that of phosphorous-doped silicon wafers.

  5. Carbon, nitrogen, and oxygen ion implantation of stainless steel

    SciTech Connect

    Rej, D.J.; Gavrilov, N.V.; Emlin, D.

    1995-12-31

    Ion implantation experiments of C, N, and O into stainless steel have been performed, with beam-line and plasma source ion implantation methods. Acceleration voltages were varied between 27 and 50 kV, with pulsed ion current densities between 1 and 10 mA/cm{sup 2}. Implanted doses ranged from 0.5 to 3 {times} 10{sup 18}cm{sup -2}, while workpiece temperatures were maintained between 25 and 800 C. Implant concentration profiles, microstructure, and surface mechanical properties of the implanted materials are reported.

  6. Crystal orientation effects on implantation of low-energy hydrogen, helium and hydrogen/helium mixtures in plasma-facing tungsten surfaces

    NASA Astrophysics Data System (ADS)

    Linn, Brian C.

    The development of plasma-facing materials (PFM) is one of the major challenges in. realizing fusion reactors. Materials deployed in PFMs must be capable of withstanding the high-flux of low-energy hydrogen and helium ions omitted from the plasma. while not hindering the plasma. Tungsten is considered a promising candidate material due to desirable material properties including its high melting temperature, good thermal conductivity and relatively low physical and chemical sputtering yields. This thesis uses molecular dynamic simulations to investigate helium and hydrogen bombardment of tungsten and the underlying physical effects (e.g. sputtering, erosion, blistering). Non-cumulative and cumulative bombardment simulations of helium, hydrogen, and hydrogen/helium bombardment of tungsten were modeled using the molecular dynamics code LAMMPS. Two orientations of monocrystalline bcc tungsten surfaces were considered, (001) and (111). Simulations were performed for temperatures ranging from 600K up to 1500K and helium / hydrogen incident energies of 20eV to 100eV . The results of these simulations showed the effect of temperature and incident particle energy on retention rates and implantation/deposition profiles in tungsten.

  7. Response of a delta-doped charge-coupled device to low energy protons and nitrogen ions

    SciTech Connect

    Lepri, S.T.; Nikzad, Shouleh; Jones, T.; Blacksberg, J.; Zurbuchen, T.H.

    2006-05-15

    We present the results of a study of the response of a delta-doped charge-coupled device (CCD) exposed to ions with energies less than 10 keV. The study of ions in the solar wind, the majority having energies in the 1-5 keV range, has proven to be vital in understanding the solar atmosphere and the near Earth space environment. Delta-doped CCD technology has essentially removed the dead layer of the silicon detector. Using the delta-doped detector, we are able to detect H{sup +} and N{sup +} ions with energies ranging from 1 to 10 keV in the laboratory. This is a remarkable improvement in the low energy detection threshold over conventional solid-state detectors, such as those used in space sensors, one example being the solar wind ion composition spectrometer (SWICS) on the Advanced Composition Explorer spacecraft, which can only detect ions with energies greater than 30 keV because of the solid-state detector's minimum energy threshold. Because this threshold is much higher than the average energy of the solar wind ions, the SWICS instrument employs a bulky high voltage postacceleration stage that accelerates ions above the 30 keV detection threshold. This stage is massive, exposes the instrument to hazardous high voltages, and is therefore problematic both in terms of price and its impact on spacecraft resources. Adaptation of delta-doping technology in future space missions may be successful in reducing the need for heavy postacceleration stages allowing for miniaturization of space-borne ion detectors.

  8. Nitrogen and boron ion implantation into electrodeposited hard chrome

    SciTech Connect

    Walter, K.C.; Tesmer, J.R.; Scarborough, W.K.; Woodring, J.S.; Nastasi, M.; Kern, K.T.

    1996-10-01

    Electrodeposited hard chrome was ion implanted with N alone, B alone, and a combination. Separate N and B implantation was done at 75 keV and incident doses of 2, 4, and 8x10{sup 17} at/cm{sup 2}. Samples with both N/B implants used 75 keV and incident dose levels of 4x10{sup 17} N- and B-at/cm{sup 2}. Beam-line system was used. Retained dose was measured using ion beam analysis, which indicated most of the incident dose was retained. Surface hardness, wear coefficient, and friction coefficient were determined by nanohardness indentation and pin-on-disk wear. At a depth of 50 nm, surface hardness increased from 18{+-}1 GPa (unimplanted) to a max of 23{+-}4 GPa for B implant and 26{+-}1 GPa for N implant. the wear coefficient was reduced by 1.3x to 7.4x, depending on implantation. N implant results in lower wear coefficients than B implant.

  9. Proposed mechanism to represent the suppression of dark current density by four orders with low energy light ion (H{sup −}) implantation in quaternary alloy-capped InAs/GaAs quantum dot infrared photodetectors

    SciTech Connect

    Mandal, A.; Ghadi, H.; Mathur, K.L.; Basu, A.; Subrahmanyam, N.B.V.; Singh, P.; Chakrabarti, S.

    2013-08-01

    Graphical abstract: - Abstract: Here we propose a carrier transport mechanism for low energy H{sup −} ions implanted InAs/GaAs quantum dot infrared photodetectors supportive of the experimental results obtained. Dark current density suppression of up to four orders was observed in the implanted quantum dot infrared photodetectors, which further demonstrates that they are effectively operational. We concentrated on determining how defect-related material and structural changes attributed to implantation helped in dark current density reduction for InAs/GaAs quantum dot infrared photodetectors. This is the first study to report the electrical carrier transport mechanism of H{sup −} ion-implanted InAs/GaAs quantum dot infrared photodetectors.

  10. Friction wear and auger analysis of iron implanted with 1.5-MeV nitrogen ions

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Jones, W. R., Jr.

    1982-01-01

    The effect of implantation of 1.5-MeV nitrogen ions on the friction and wear characteristics of pure iron sliding against steel was studied in a pin-on disk apparatus. An implantation dose of 5 x 10 to the 17th power ions/sq cm was used. Small reductions in initial and steady-state wear rates were observed for nitrogen-implanted iron riders as compared with unimplanted controls. Auger electron spectroscopy revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 15 at. % at a depth of 8 x 10 to the -7th m. A similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration, thus giving no evidence for diffusion of nitrogen beyond the implanted range.

  11. Surface characterization and biocompatibility of titanium alloys implanted with nitrogen by Hardion+ technology.

    PubMed

    Gordin, D M; Gloriant, T; Chane-Pane, V; Busardo, D; Mitran, V; Höche, D; Vasilescu, C; Drob, S I; Cimpean, A

    2012-12-01

    In this study, the new Hardion+ micro-implanter technology was used to modify surface properties of biomedical pure titanium (CP-Ti) and Ti-6Al-4V ELI alloy by implantation of nitrogen ions. This process is based on the use of an electron cyclotron resonance ion source to produce a multienergetic ion beam from multicharged ions. After implantation, surface analysis methods revealed the formation of titanium nitride (TiN) on the substrate surfaces. An increase in superficial hardness and a significant reduction of friction coefficient were observed for both materials when compared to non-implanted samples. Better corrosion resistance and a significant decrease in ion release rates were observed for N-implanted biomaterials due to the formation of the protective TiN layer on their surfaces. In vitro tests performed on human fetal osteoblasts indicated that the cytocompatibility of N-implanted CP-Ti and Ti-6Al-4V alloy was enhanced in comparison to that of the corresponding non treated samples. Consequently, Hardion+ implantation technique can provide titanium alloys with better qualities in terms of corrosion resistance, cell proliferation, adhesion and viability.

  12. Modification of diamond-like carbon films by nitrogen incorporation via plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Flege, S.; Hatada, R.; Hoefling, M.; Hanauer, A.; Abel, A.; Baba, K.; Ensinger, W.

    2015-12-01

    The addition of nitrogen to diamond-like carbon films affects properties such as the inner stress of the film, the conductivity, biocompatibility and wettability. The nitrogen content is limited, though, and the maximum concentration depends on the preparation method. Here, plasma immersion ion implantation was used for the deposition of the films, without the use of a separate plasma source, i.e. the plasma was generated by a high voltage applied to the samples. The plasma gas consisted of a mixture of C2H4 and N2, the substrates were silicon and glass. By changing the experimental parameters (high voltage, pulse length and repetition rate and gas flow ratio) layers with different N content were prepared. Additionally, some samples were prepared using a DC voltage. The nitrogen content and bonding was investigated with SIMS, AES, XPS, FTIR and Raman spectroscopy. Their influence on the electrical resistivity of the films was investigated. Depending on the preparation conditions different nitrogen contents were realized with maximum contents around 11 at.%. Those values were compared with the nitrogen concentration that can be achieved by implantation of nitrogen into a DLC film.

  13. Microstructure and oxidation behavior of high strength steel AISI 410 implanted with nitrogen ion

    NASA Astrophysics Data System (ADS)

    Bandriyana, Ismoyo, Agus Hadi; Sujitno, Tjipto; Dimyati, A.

    2016-04-01

    Surface treatment by implantation with nitrogen-ion was performed on the commercial feritic high strength steel AISI 410 which is termed for high temperature applications. The aim of this research was focused on the surface modification to improve its high temperature oxidation property in the early stages. Ion implantation was carried out at acceleration energy of 100 KeV and ion current 10 mA for 30, 60 and 90 minutes. The samples were subjected to the high temperature oxidation test by means of thermogravimetry in a magnetic suspension balance (MSB) at 500 °C for 5 hours. The scanning electron microscopy (SEM), X-ray diffraction spectrometry (XRD) and Vickers Hardness measurement were used for sample characterization. The formation of ferro-nitride phase after implantation did not occur, however a thin layer considered to contain nitrogen interstitials was detected. The oxidation of both samples before and after implantation followed parabolic kinetics indicating inward growth of oxide scale characteristically due to diffusion of oxygen anions towards matrix surface. After oxidation test relativelly stable oxide scales were observed. Oxidation rates decreased proportionally with the increasing of implantation time due to the formation of oxide layer which is considered to be effectiv inhibitor for the oxygen diffusion.

  14. Production and characterization of a nitrogen-implanted Fe standard to calibrate PIGE measurements

    SciTech Connect

    Rodrigues, C. L.; Silva, T. F.; Added, N.; Santos, H. C.; Tabacniks, M. H.

    2014-11-11

    Three calibration standard was produced by ion implantation of nitrogen in samples of Armco iron (99.7% iron). The samples was irradiated with nitrogen ion beams at several different energies (between 4 keV and 40 keV), and the ion doses were adjusted to obtain an uniform depth profile, using simulations with SRIM code. Two standards, one thick and other a foil (1.62mg/cm{sup 2}), was irradiated at same time with total nominal dose of 6.6×10{sup −16} atoms/cm{sup 2} distributed in a region of 100 nm in depth, with an average concentration of 9.0% nitrogen in iron. The third sample uses the same profile, but with a small dose, 1.1×10{sup −16} atoms/cm{sup 2} and average concentration of 1.5% nitrogen. The characterization of the implanted samples was done using RBS and NRA techniques to quantification of nitrogen.

  15. Short-range ordering of ion-implanted nitrogen atoms in SiC-graphene

    SciTech Connect

    Willke, P.; Druga, T.; Wenderoth, M.; Amani, J. A.; Weikert, S.; Hofsäss, H.; Thakur, S.; Maiti, K.

    2014-09-15

    We perform a structural analysis of nitrogen-doped graphene on SiC(0001) prepared by ultra low-energy ion bombardment. Using scanning tunneling microscopy, we show that nitrogen atoms are incorporated almost exclusively as graphitic substitution in the graphene honeycomb lattice. With an irradiation energy of 25 eV and a fluence of approximately 5 × 10{sup 14 }cm{sup −2}, we achieve a nitrogen content of around 1%. By quantitatively comparing the position of the N-atoms in the topography measurements with simulated random distributions, we find statistically significant short-range correlations. Consequently, we are able to show that the dopants arrange preferably at lattice sites given by the 6 × 6-reconstruction of the underlying substrate. This selective incorporation is most likely triggered by adsorbate layers present during the ion bombardment. This study identifies low-energy ion irradiation as a promising method for controlled doping in epitaxial graphene.

  16. Nitrogen implantation effects on the chemical bonding and hardness of boron and boron nitride coatings

    SciTech Connect

    Anders, S; Felter, T; Hayes, J; Jankowski, A F; Patterson, R; Poker, D; Stamler, T

    1999-02-08

    Boron nitride (BN) coatings are deposited by the reactive sputtering of fully dense, boron (B) targets utilizing an argon-nitrogen (Ar-N{sub 2}) reactive gas mixture. Near-edge x-ray absorption fine structure analysis reveals features of chemical bonding in the B 1s photoabsorption spectrum. Hardness is measured at the film surface using nanoindentation. The BN coatings prepared at low, sputter gas pressure with substrate heating are found to have bonding characteristic of a defected hexagonal phase. The coatings are subjected to post-deposition nitrogen (N{sup +} and N{sub 2}{sup +}) implantation at different energies and current densities. The changes in film hardness attributed to the implantation can be correlated to changes observed in the B 1s NEXAFS spectra.

  17. Molecular dynamics simulations of shallow nitrogen and silicon implantation into diamond

    NASA Astrophysics Data System (ADS)

    Lehtinen, Ossi; Naydenov, Boris; Börner, Pia; Melentjevic, Kristina; Müller, Christoph; McGuinness, Liam Paul; Pezzagna, Sebastien; Meijer, Jan; Kaiser, Ute; Jelezko, Fedor

    2016-01-01

    A solid understanding of the implantation process of N and Si ions into diamond is needed for the controlled creation of shallow color centers for quantum computing, simulation, and sensing applications. Here, molecular dynamics simulations of the shallow implantation of N and Si ions into diamond is simulated at 100-5000 eV kinetic energies and different angles of incidence. We find that ion channeling is an important effect with an onset energy depending on the crystal orientation. Consequently, the molecular dynamics simulations produce improved predictions as compared to standard Monte Carlo simulations. When implanting in a channeling direction, the spatial distribution of the channeled ions becomes markedly narrow, allowing a higher degree of control over the location of the nitrogen vacancy (NV-) centers. A contamination layer on the ion entry surface reduces the fraction of channeled ions. A comparison to an experimentally determined depth profile based on a NMR signal from protons yields a quantitative agreement, validating the simulation approach.

  18. The influence of nitrogen ion implantation on microhardness of the Stellite 6 alloy

    NASA Astrophysics Data System (ADS)

    Budzyński, P.; Kamiński, M.; Pałka, K.; Droździel, A.; Wiertel, M.

    2016-09-01

    Cobalt alloys known as Stellite used to produce or surfacing machine elements subjected to combustion gases and heat. They are used a currently in the manufacture of valves and valve seats in internal combustion engines. Because of the small thermal conductivity, stellite may not be subjected heat treatment. In order to improve the mechanical properties of cobalt alloys, samples were implanted with nitrogen ions with 65 keV energy and ion dose of 1·1016, 5·1016, 1·1017 N+/cm2. The influence of ion implantation on properties of strength was determined by measuring microhardness using a Vickers hardness test. The measurement results allowed to determine the increase in the microhardness of 20% with dose 5·1016 N+/cm2 compared to the sample not implanted. Implantation of nitrogen ions can increase the strength of the valves and the valve seats having Stellite without changing the external dimensions of the final element, and without interfering with its inner structure by low-temperature of modification the surface layer.

  19. High-Sensitivity Temperature Sensing Using an Implanted Single Nitrogen-Vacancy Center Array in Diamond

    NASA Astrophysics Data System (ADS)

    Wang, Guanzhong; Wang, Junfeng; Advanced Thinfilm Laboratory, University of Science; Technology of China Team

    2015-03-01

    We present a high-sensitivity temperature detection using an implanted single Nitrogen-Vacancy center array in diamond. The high-order Thermal Carr-Purcell-Meiboom-Gill (TCPMG) method was performed on the implanted single nitrogen vacancy (NV) center in diamond in a static magnetic field. We demonstrated that under small detunings for the two driving microwave frequencies, the oscillation frequency of the induced fluorescence of the NV center equals approximately to the average of the detunings of the two driving fields. On basis of the conclusion, the zero-field splitting D for the NV center and the corresponding temperature could be determined. The experiment showed that the coherence time for the high-order TCPMG was effectively extended, particularly up to 108 μs for TCPMG-8, about 14 times of the value 7.7 μs for thermal Ramsey method. This coherence time corresponded to a thermal sensitivity of 10.1 mK/Hz1/2. We also detected the temperature distribution on the surface of a diamond chip by using the implanted NV center array with the TCPMG-3. Our approach implies the feasibility for using implanted NV centers in high-quality diamonds to detect temperatures with high-sensitivity and nanoscale resolution. This work was supported by the National Basic Research Program of China (2013CB921800, 2011CB921400) and the Natural Science Foundation of China (Grant Nos. 11374280, 50772110).

  20. Corrosion behaviors of Mo coating on stainless steel 316 substrates implanted by different nitrogen ion fluences

    NASA Astrophysics Data System (ADS)

    Mojtahedzadeh Larijani, Madjid; Bafandeh, Nastaran

    2014-03-01

    The molybdenum nitride coating was produced by nitrogen ion implantation of the molybdenum layer deposited on the stainless steel 316 (SS) substrates. At first, molybdenum layers were deposited on the substrates by ion beam sputtering method, then nitrogen ions with an energy of 30 keV and a fluence between 1×1017 and 12×1017 N+ cm-2 were implanted in Mo/SS system. Crystal structure and topography of the surface are investigated by grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) image respectively. XRD patterns showed the formation of molybdenum nitride phases in all implanted samples. Corrosion tests showed that the corrosion resistance of the samples strongly depends on the nitrogen applied fluences. A considerable improvement of corrosion performance by increasing ions fluences was observed. The lowest corrosion current density with amount of 0.1 μA/cm2 was obtained at 12×1017 ions/cm2 fluence in our case.

  1. Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen

    PubMed Central

    Sousa, Marco A.; Esteves, Teresa C.; Sedrine, Nabiha Ben; Rodrigues, Joana; Lourenço, Márcio B.; Redondo-Cubero, Andrés; Alves, Eduardo; O'Donnell, Kevin P.; Bockowski, Michal; Wetzel, Christian; Correia, Maria R.; Lorenz, Katharina; Monteiro, Teresa

    2015-01-01

    We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity. The green band was found to be surprisingly stable on annealing up to 1400°C. A broad blue band dominates the low temperature PL after thermal annealing in both samples. This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment. PMID:25853988

  2. Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen

    NASA Astrophysics Data System (ADS)

    Sousa, Marco A.; Esteves, Teresa C.; Sedrine, Nabiha Ben; Rodrigues, Joana; Lourenço, Márcio B.; Redondo-Cubero, Andrés; Alves, Eduardo; O'Donnell, Kevin P.; Bockowski, Michal; Wetzel, Christian; Correia, Maria R.; Lorenz, Katharina; Monteiro, Teresa

    2015-04-01

    We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity. The green band was found to be surprisingly stable on annealing up to 1400°C. A broad blue band dominates the low temperature PL after thermal annealing in both samples. This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment.

  3. Improvement of Vitamin K2 Production by Escherichia sp. with Nitrogen Ion Beam Implantation Induction

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Wang, Li; Zheng, Zhiming; Wang, Peng; Zhao, Genhai; Liu, Hui; Gong, Guohong; Wu, Hefang; Liu, Hongxia; Tan, Mu; Li, Zhemin

    2015-02-01

    Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra. In this work, N+ ion beam implantation was used to enhance Escherichia sp. in vitamin K2 yield. Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K2 yield of mutant FM5-632. The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L, that is four times that of the original strain, was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×1013 ions/cm2. A further optimization increased the yield of the mutant by 39.7%, i.e. 172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of (per liter): 15.31 g glycerol, 10 g peptone, 2.89 g yeast extract, 5 g K2HPO4, 1 g NaCl, 0.5 g MgSO4·7H2O and 0.04 g cedar wood oil, incubated at 33 °C, pH 7.0 and 180 rpm for 120 h.

  4. Significantly Enhanced Visible Light Photoelectrochemical Activity in TiO₂ Nanowire Arrays by Nitrogen Implantation.

    PubMed

    Wang, Gongming; Xiao, Xiangheng; Li, Wenqing; Lin, Zhaoyang; Zhao, Zipeng; Chen, Chi; Wang, Chen; Li, Yongjia; Huang, Xiaoqing; Miao, Ling; Jiang, Changzhong; Huang, Yu; Duan, Xiangfeng

    2015-07-01

    Titanium oxide (TiO2) represents one of most widely studied materials for photoelectrochemical (PEC) water splitting but is severely limited by its poor efficiency in the visible light range. Here, we report a significant enhancement of visible light photoactivity in nitrogen-implanted TiO2 (N-TiO2) nanowire arrays. Our systematic studies show that a post-implantation thermal annealing treatment can selectively enrich the substitutional nitrogen dopants, which is essential for activating the nitrogen implanted TiO2 to achieve greatly enhanced visible light photoactivity. An incident photon to electron conversion efficiency (IPCE) of ∼10% is achieved at 450 nm in N-TiO2 without any other cocatalyst, far exceeding that in pristine TiO2 nanowires (∼0.2%). The integration of oxygen evolution reaction (OER) cocatalyst with N-TiO2 can further increase the IPCE at 450 nm to ∼17% and deliver an unprecedented overall photocurrent density of 1.9 mA/cm(2), by integrating the IPCE spectrum with standard AM 1.5G solar spectrum. Systematic photoelectrochemical and electrochemical studies demonstrated that the enhanced PEC performance can be attributed to the significantly improved visible light absorption and more efficient charge separation. Our studies demonstrate the implantation approach can be used to reliably dope TiO2 to achieve the best performed N-TiO2 photoelectrodes to date and may be extended to fundamentally modify other semiconductor materials for PEC water splitting.

  5. The influence of nitrogen ion implantation on the tribological properties of piston rings made of Hardox and Raex steels

    NASA Astrophysics Data System (ADS)

    Budzyński, P.; Kamiński, M.; Pyszniak, K.

    2016-09-01

    The implantation of nitrogen, carbon, and oxygen can be used for enhancing the tribological properties of critical components for internal combustion engines. Hardox and Raex steels have very similar strength parameters as for steel used for piston rings in internal combustion engines. An essential criterion when selecting material for the production of piston rings is a low friction factor and a low wear index. The aim of this study was to determine the extent to which these parameters can be enhanced by nitrogen ion implantation. Samples were implanted with nitrogen ions with 65 keV energy and the fluence of implanted ions set to 1.1017 N + /cm2. Friction and wear measurements were performed on a pin-on disc stand. The results demonstrate that implantation with nitrogen ions significantly reduces the friction factor and wear of Hardox 450 and Raex 400 steels. Implantation can and should be used for enhancing the tribological properties of steel used for friction elements in internal combustion engines, particularly when heat treatment is excluded. Final elements can be subjected to implantation, as the process does not change their dimensions.

  6. The effect of annealing on the Knoop microhardness of nitrogen implanted Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Nath, V. C.; Sood, D. K.; Manory, R. R.

    1991-07-01

    The implantation of the Ti6Al4V alloy with nitrogen has been previously studied, and the treatment has been shown to improve the microhardness significantly [R.G. Vardiman, Defect and Diffusion Forum 57/58 (1988) 135, and references therein]. The effects of post-implantation annealing on the properties has not been studied systematically, and this is the principal aim of the RMIT work. Initial results of this study are presented and discussed. It was found that N + implantation of this alloy at 80 keV with fluences varying in the range (0.5-1.5) × 10 17ions/cm 2 caused an improvement in Knoop hardness up to 100%. Rutherford backscattering results show a buried layer containing up to 25% nitrogen in the as-implanted specimens at a depth of 130 nm. After annealing the sample implanted with 1.5 × 10 17 at 705°C, both the nitrogen concentration and the depth of the layer decrease to approximately half of their as-implanted values. The observed reduction in hardness can be attributed to the decrease in the nitrogen concentration of the buried layer, as well as to repair of the lattice. These results may indicate that only a limited amount of TiN forms directly during implantation.

  7. A nuclear reaction analysis and optical microscopy study on controlled growth of large SiC nanocrystals on Si formed by low-energy ion implantation and electron beam annealing

    NASA Astrophysics Data System (ADS)

    Markwitz, A.; Lucas, F.; Rusterucci, J.; Kennedy, J.; Trompetter, W. J.; Rudolphi, M.; Ryan, M.; White, V.; Johnson, S.

    2006-08-01

    Ion implantation of 20 keV 12C+ ions into (1 0 0), p-type silicon with ion fluence of 8 × 1016 at. cm-2 followed by an electron beam annealing under high vacuum conditions has been performed to investigate the formation of crystalline nano-scale SiC features on the silicon surface. Depending on the implantation and annealing conditions, the SiC nanocrystal numbers and average spacing can be controlled by adjusting the implantation and annealing conditions. Typically 300-1000 SiC nanocrystals are produced per 1000 μm2 spaced 0.7-1.2 ± 0.1 μm. Nuclear reaction analysis measurements using the deuterium induced 12C(d, p)13C reaction show that carbon is present in the implanted and annealed samples and varies only to a small degree by the annealing time. However, by not using a liquid nitrogen trap surrounding the targets during implantation, the carbon contamination on the surface reduces the number of SiC nanocrystals and increases their average distance. Specific results are discussed.

  8. Determination of Ni Release in NiTi SMA with Surface Modification by Nitrogen Plasma Immersion Ion Implantation

    NASA Astrophysics Data System (ADS)

    de Camargo, Eliene Nogueira; Oliveira Lobo, Anderson; Silva, Maria Margareth Da; Ueda, Mario; Garcia, Edivaldo Egea; Pichon, Luc; Reuther, Helfried; Otubo, Jorge

    2011-07-01

    NiTi SMA is a promising material in the biomedical area due to its mechanical properties and biocompatibility. However, the nickel in the alloy may cause allergic and toxic reactions and thus limiting its applications. It was evaluated the influence of surface modification in NiTi SMA by nitrogen plasma immersion ion implantation (varying temperatures, and exposure time as follows: <250 °C/2 h, 290 °C/2 h, and 560 °C/1 h) in the amount of nickel released using immersion test in simulated body fluid. The depth of the nitrogen implanted layer increased as the implantation temperature increased resulting in the decrease of nickel release. The sample implanted in high implantation temperature presented 35% of nickel release reduction compared to reference sample.

  9. Effects of nitrogen ion implantation time on tungsten films deposited by DC magnetron sputtering on AISI 410 martensitic stainless steel

    NASA Astrophysics Data System (ADS)

    Malau, Viktor; Ilman, Mochammad Noer; Iswanto, Priyo Tri; Jatisukamto, Gaguk

    2016-03-01

    Nitrogen ion implantation time on tungsten thin film deposited on surface of AISI 410 steel has been performed. Tungsten thin film produced by dc magnetron sputtering method was deposited on AISI 410 martensitic stainless steel substrates, and then the nitrogen ions were implanted on tungsten thin film. The objective of this research is to investigate the effects of implantation deposition time on surface roughness, microhardness, specific wear and corrosion rate of nitrogen implanted on tungsten film. Magnetron sputtering process was performed by using plasma gas of argon (Ar) to bombardier tungsten target (W) in a vacuum chamber with a pressure of 7.6 x 10-2 torr, a voltage of 300 V, a sputter current of 80 mA for sputtered time of 10 minutes. Nitrogen implantation on tungsten film was done with an initial pressure of 3x10-6 mbar, a fluence of 2 x 1017 ions/cm2, an energy of 100 keV and implantation deposition times of 0, 20, 30 and 40 minutes. The surface roughness, microhardness, specific wear and corrosion rate of the films were evaluated by surfcorder test, Vickers microhardness test, wear test and potentiostat (galvanostat) test respectively. The results show that the nitrogen ions implanted deposition time on tungsten film can modify the surface roughness, microhardness, specific wear and corrosion rate. The minimum surface roughness, specific wear and corrosion rate can be obtained for implantation time of 20 minutes and the maximum microhardness of the film is 329 VHN (Vickers Hardness Number) for implantation time of 30 minutes. The specific wear and corrosion rate of the film depend directly on the surface roughness.

  10. High-sensitivity temperature sensing using an implanted single nitrogen-vacancy center array in diamond

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Feng, Fupan; Zhang, Jian; Chen, Jihong; Zheng, Zhongcheng; Guo, Liping; Zhang, Wenlong; Song, Xuerui; Guo, Guoping; Fan, Lele; Zou, Chongwen; Lou, Liren; Zhu, Wei; Wang, Guanzhong

    2015-04-01

    We presented a high-sensitivity temperature detection using an implanted single nitrogen-vacancy (NV) center array in diamond. The high-order thermal Carr-Purcell-Meiboom-Gill (TCPMG) method was performed on the implanted single NV center in diamond in a static magnetic field. We demonstrated that under small detunings for the two driving microwave frequencies, the oscillation frequency of the induced fluorescence of the NV center equals approximately the average of the detunings of the two driving fields. On the basis of the conclusion, the zero-field splitting D for the NV center and the corresponding temperature could be determined. The experiment showed that the coherence time for the high-order TCPMG was effectively extended, particularly up to 108 μ s for TCPMG-8, about 14 times the value 7.7 μ s for thermal Ramsey method. This coherence time corresponded to a thermal sensitivity of 10.1 mK/Hz1 /2. We also detected the temperature distribution on the surface of a diamond chip in three different circumstances by using the implanted NV center array with the TCPMG-3 method. The experiment implies the feasibility of using implanted NV centers in high-quality diamonds to detect temperatures in biology, chemistry, materials science, and microelectronic systems with high sensitivity and nanoscale resolution.

  11. Enhancing Electrocatalytic Oxygen Reduction on Nitrogen-Doped Graphene by Active Sites Implantation

    PubMed Central

    Feng, Leiyu; Yang, Lanqin; Huang, Zujing; Luo, Jingyang; Li, Mu; Wang, Dongbo; Chen, Yinguang

    2013-01-01

    The shortage of nitrogen active sites and relatively low nitrogen content result in unsatisfying eletrocatalytic activity and durability of nitrogen-doped graphene (NG) for oxygen reduction reaction (ORR). Here we report a novel approach to substantially enhance electrocatalytic oxygen reduction on NG electrode by the implantation of nitrogen active sites with mesoporous graphitic carbon nitride (mpg-C3N4). Electrochemical characterization revealed that in neutral electrolyte the resulting NG (I-NG) exhibited super electrocatalytic activity (completely 100% of four-electron ORR pathway) and durability (nearly no activity change after 100000 potential cyclings). When I-NG was used as cathode catalyst in microbial fuel cells (MFCs), power density and its drop percentage were also much better than the NG and Pt/C ones, demonstrating that the current I-NG was a perfect alternative to Pt/C and offered a new potential for constructing high-performance and less expensive cathode which is crucial for large-scale application of MFC technology. PMID:24264379

  12. Enhancing Electrocatalytic Oxygen Reduction on Nitrogen-Doped Graphene by Active Sites Implantation

    NASA Astrophysics Data System (ADS)

    Feng, Leiyu; Yang, Lanqin; Huang, Zujing; Luo, Jingyang; Li, Mu; Wang, Dongbo; Chen, Yinguang

    2013-11-01

    The shortage of nitrogen active sites and relatively low nitrogen content result in unsatisfying eletrocatalytic activity and durability of nitrogen-doped graphene (NG) for oxygen reduction reaction (ORR). Here we report a novel approach to substantially enhance electrocatalytic oxygen reduction on NG electrode by the implantation of nitrogen active sites with mesoporous graphitic carbon nitride (mpg-C3N4). Electrochemical characterization revealed that in neutral electrolyte the resulting NG (I-NG) exhibited super electrocatalytic activity (completely 100% of four-electron ORR pathway) and durability (nearly no activity change after 100000 potential cyclings). When I-NG was used as cathode catalyst in microbial fuel cells (MFCs), power density and its drop percentage were also much better than the NG and Pt/C ones, demonstrating that the current I-NG was a perfect alternative to Pt/C and offered a new potential for constructing high-performance and less expensive cathode which is crucial for large-scale application of MFC technology.

  13. Highly tunable formation of nitrogen-vacancy centers via ion implantation

    SciTech Connect

    Sangtawesin, S.; Brundage, T. O.; Atkins, Z. J.; Petta, J. R.

    2014-08-11

    We demonstrate highly tunable formation of nitrogen-vacancy (NV) centers using 20 keV {sup 15}N{sup +} ion implantation through arrays of high-resolution apertures fabricated with electron beam lithography. By varying the aperture diameters from 80 to 240 nm, as well as the average ion fluences from 5×10{sup 10} to 2 × 10{sup 11} ions/cm{sup 2}, we can control the number of ions per aperture. We analyze the photoluminescence on multiple sites with different implantation parameters and obtain ion-to-NV conversion yields of 6%–7%, consistent across all ion fluences. The implanted NV centers have spin dephasing times T{sub 2}{sup *} ∼ 3 μs, comparable to naturally occurring NV centers in high purity diamond with natural abundance {sup 13}C. With this technique, we can deterministically control the population distribution of NV centers in each aperture, allowing for the study of single or coupled NV centers and their integration into photonic structures.

  14. Correlation between defect and magnetism of low energy Ar+9 implanted and un-implanted Zn0.95Mn0.05O thin films suitable for electronic application

    NASA Astrophysics Data System (ADS)

    Neogi, S. K.; Midya, N.; Pramanik, P.; Banerjee, A.; Bhattacharyya, A.; Taki, G. S.; Krishna, J. B. M.; Bandyopadhyay, S.

    2016-06-01

    The structural, morphological, optical and magnetic properties of Ar+9 implanted 5 at% Mn doped ZnO films have been investigated to detect the correlation between ferromagnetism (FM) and defect. Sol-gel derived films were implanted with fluences 0 (un-implanted), 5×1014 (low), 1015 (intermediate) and 1016 (high) ions/cm2. Rutherford back scattering (RBS), X-ray diffraction (XRD), atomic force microscope (AFM) and magnetic force microscope (MFM), UV-visible, photoluminescence and X-ray absorption spectroscopy (XAS) and superconducting quantum interference device vibrating sample magnetometer (SQUID VSM) were employed for investigation. XRD indicated single phase nature of the films. Absence of impurity phase has been confirmed from several other measurements also. Ion implantation induces a large concentration of point defects into the films as identified from optical study. All films exhibit intrinsic FM at room temperature (RT). The magnetization attains the maximum for the film implanted with fluence 1016 ions/cm2 with saturation magnetization (MS) value 0.69 emu/gm at RT. Magnetic properties of the films were interpreted using bound magnetic polaron (BMP). BMP generated from the intrinsic exchange interaction of Mn2+ ions and VZn related defects actually controls the FM. The practical utility of these films in transparent spin electronic device has also been exhibited.

  15. Influence of ionizing irradiation in air and nitrogen for sterilization of surgical grade polyethylene for implants

    NASA Astrophysics Data System (ADS)

    Streicher, R. M.

    The influence of the atmosphere and the applied dose during ionizing radiation treatment on selected properties of ultra high molecular weight polyethylene (UHMWPE) have been investigated. A linear correlation between extinction coefficient and applied dosis in air from 6 to 125 kGy was found, while oxidation was not linear with irradiation in nitrogen. Bacteria survival rate shows a necessary minimum dose of 15 kGy for assured sterility of the product. Post reaction of latent free radicals in UHMWPE created during irradiation, which react or recombine time- and environment dependent, has also been investigated after storage of UHMWPE-films in air and nitrogen at 21°C and in water at body temperature 37°C for up to nine months. Results show that the properties of UHMWPE after radiation-sterilization change depending on time, the absorbed dose, the atmosphere where irradiation took place and the environment of storage. UHMWPE, which mainly crosslinks during irradiation degrades by an oxidation process after sterilizing when stored in air and even more in water at body temperature. So irradiation and storage in nitrogen before implantation in the human body is beneficial.

  16. Formation and properties of high-dose nitrogen implanted epitaxially grown Gd2O3 on silicon

    NASA Astrophysics Data System (ADS)

    Joseph, A.; Tetzlaff, D.; Schmidt, J.; Böttger, R.; Wietler, T. F.; Osten, H. J.

    2016-10-01

    The effects of nitrogen incorporation by high-dose ion implantation in epitaxial Gd2O3 films on Si(111) followed by annealing have been investigated. Nitrogen incorporation is believed to occur by filling the oxygen vacancies or by removing hydroxyl group ions in gadolinium oxide (Gd2O3). The nitrogen content in the oxide layer has been altered by changing the implantation dose. The impact of nitrogen incorporation on Gd-O bonding is studied using X-ray photoelectron spectroscopy. A shift in the Gd and O peak positions indicate the presence of nitrogen in the layer. Raman spectroscopy reveals heavy structural changes. The newly appearing structure is crystalline, but not in agreement with either the known bixbyite (Gd2O3) or rocksalt (GdN) structure. Electron microscopic investigations reveal the formation of cracks and small areas with lower densities or even voids. That structure exhibits similarities with transmission electron microscopy images of gadolinium nitride (GdN) layers. The electronic band gap of Gd2O3 estimated from O1s plasmon energy loss measurements was found to decrease significantly by the incorporation of nitrogen. Reduction in the valence band and conduction band offset is obtained as a function of implantation dose.

  17. In vivo biocompatibility of boron doped and nitrogen included conductive-diamond for use in medical implants.

    PubMed

    Garrett, David J; Saunders, Alexia L; McGowan, Ceara; Specks, Joscha; Ganesan, Kumaravelu; Meffin, Hamish; Williams, Richard A; Nayagam, David A X

    2016-01-01

    Recently, there has been interest in investigating diamond as a material for use in biomedical implants. Diamond can be rendered electrically conducting by doping with boron or nitrogen. This has led to inclusion of boron doped and nitrogen included diamond elements as electrodes and/or feedthroughs for medical implants. As these conductive device elements are not encapsulated, there is a need to establish their clinical safety for use in implants. This article compares the biocompatibility of electrically conducting boron doped diamond (BDD) and nitrogen included diamond films and electrically insulating poly crystalline diamond films against a silicone negative control and a BDD sample treated with stannous octoate as a positive control. Samples were surgically implanted into the back muscle of a guinea pig for a period of 4-15 weeks, excised and the implant site sectioned and submitted for histological analysis. All forms of diamond exhibited a similar or lower thickness of fibrotic tissue encapsulating compared to the silicone negative control samples. All forms of diamond exhibited similar or lower levels of acute, chronic inflammatory, and foreign body responses compared to the silicone negative control indicating that the materials are well tolerated in vivo.

  18. In vivo biocompatibility of boron doped and nitrogen included conductive-diamond for use in medical implants.

    PubMed

    Garrett, David J; Saunders, Alexia L; McGowan, Ceara; Specks, Joscha; Ganesan, Kumaravelu; Meffin, Hamish; Williams, Richard A; Nayagam, David A X

    2016-01-01

    Recently, there has been interest in investigating diamond as a material for use in biomedical implants. Diamond can be rendered electrically conducting by doping with boron or nitrogen. This has led to inclusion of boron doped and nitrogen included diamond elements as electrodes and/or feedthroughs for medical implants. As these conductive device elements are not encapsulated, there is a need to establish their clinical safety for use in implants. This article compares the biocompatibility of electrically conducting boron doped diamond (BDD) and nitrogen included diamond films and electrically insulating poly crystalline diamond films against a silicone negative control and a BDD sample treated with stannous octoate as a positive control. Samples were surgically implanted into the back muscle of a guinea pig for a period of 4-15 weeks, excised and the implant site sectioned and submitted for histological analysis. All forms of diamond exhibited a similar or lower thickness of fibrotic tissue encapsulating compared to the silicone negative control samples. All forms of diamond exhibited similar or lower levels of acute, chronic inflammatory, and foreign body responses compared to the silicone negative control indicating that the materials are well tolerated in vivo. PMID:25611731

  19. Etching and structural changes in nitrogen plasma immersion ion implanted polystyrene films

    NASA Astrophysics Data System (ADS)

    Gan, B. K.; Bilek, M. M. M.; Kondyurin, A.; Mizuno, K.; McKenzie, D. R.

    2006-06-01

    Plasma immersion ion implantation (PIII), with nitrogen ions of energy 20 keV in the fluence range of 5 × 1014-2 × 1016 ions cm-2, is used to modify 100 nm thin films of polystyrene on silicon wafer substrates. Ellipsometry is used to study changes in thickness with etching and changes in optical constants. Two distinctly different etch rates are observed as the polymer structure is modified. FTIR spectroscopy data reveals the structural changes, including changes in aromatic and aliphatic groups and oxidation and carbonisation processes, occurring in the polystyrene film as a function of the ion fluence. The transformation to a dense amorphous carbon-like material was observed to progress through an intermediate structural form containing a high concentration of Cdbnd C and Cdbnd O bonds.

  20. Electronic transport and localization in nitrogen-doped graphene devices using hyperthermal ion implantation

    NASA Astrophysics Data System (ADS)

    Friedman, Adam L.; Cress, Cory D.; Schmucker, Scott W.; Robinson, Jeremy T.; van 't Erve, Olaf M. J.

    2016-04-01

    Hyperthermal ion implantation offers a controllable method of producing high-quality substitutionally doped graphene with nitrogen, an n -type dopant that has great potential for graphene electronics and spintronics applications where high carrier concentration, uniform doping, and minimal vacancy defect concentration is desired. Here we examine the transport properties of monolayer graphene sheets as a function of implantation beam energy and dose. We observe a transition from weak to strong localization that varies as a function of carrier concentration. For nominally equivalent doses, increased N ion energy results in an increasing magnetoresistance magnitude, reaching a value of approximately -5.5% at 5000 Oe, which we discuss in the context of dopant concentration and defect formation. We use a model for the temperature dependence of the conductivity that takes into account both temperature activation, due to the formation of a transport gap, and Mott variable-range hopping, due to the formation of defects, to further study the electronic properties of the doped films as a function of dose and N ion energy. We find that the temperature activation component dominates the behavior.

  1. Structure and tribological performance by nitrogen and oxygen plasma based ion implantation on Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Feng, Xingguo; Sun, Mingren; Ma, Xinxin; Tang, Guangze

    2011-09-01

    Ti6Al4V alloy was implanted with nitrogen-oxygen mixture by using plasma based ion implantation (PBII) at pulsed voltage -10, -30 and -50 kV. The implantation was up to 6 × 1017 ions/cm2 fluence. The changes in chemical composition, structure and hardness of the modified surfaces were studied by XPS and nanoindentation measurements. According to XPS, it was found that the modified layer was predominantly TiO2, but contained small amounts of TiO, Ti2O3, TiN and Al2O3 between the outmost layer and metallic substrate. Surface hardness and wear resistance of the samples increased significantly after PBII treatment, the wear rate of the sample implanted N2-O2 mixture at -50 kV decreased eight times than the untreated one. The sample implanted N2-O2 mixture showed better wear resistance than that of the sample only implanted oxygen at - 50 kV. The wear mechanism of untreated sample was abrasive-dominated and adhesive, and the wear scar of the sample implanted at -50 kV was characterized by abrasive wear-type ploughing.

  2. Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications.

    PubMed

    Gordin, D M; Busardo, D; Cimpean, A; Vasilescu, C; Höche, D; Drob, S I; Mitran, V; Cornen, M; Gloriant, T

    2013-10-01

    In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility.

  3. Enhancement of nitrogen and phosphorus removal from eutrophic water by economic plant annual ryegrass (Lolium multiflorum) with ion implantation.

    PubMed

    Li, Miao; Sheng, Guo-ping; Wu, Yue-jin; Yu, Zeng-liang; Bañuelos, Gary S; Yu, Han-qing

    2014-01-01

    Severe eutrophication of surface water has been a major problem of increasing environmental concern worldwide. In the present study, economic plant annual ryegrass (Lolium multiflorum) was grown in floating mats as an economic plant-based treatment system to evaluate its potential after ion implantation for removing nutrients in simulated eutrophic water. The specific weight growth rate of L. multiflorum with ion implantation was significantly greater than that of the control, and the peroxidase, nitrate reductase, and acid phosphatase activities of the irradiated L. multiflorum were found to be greater than those plants without ion implantation. Higher total nitrogen (TN) and total phosphorus (TP) removal efficiencies were obtained for the L. multiflorum irradiated with 25 keV 5.2 × 10(16) N(+) ions/cm(2) and 30 keV 4.16 × 10(16) N(+) ions/cm(2), respectively (p < 0.05). Furthermore, the nitrogen and phosphorus contents in the plant biomass with ion implantation were also greater than those in the control and were positively correlated with TN and TP supplied. L. multiflorum itself was directly responsible for 39-49 and 47-58 % of the overall N and P removal in the experiment, respectively. The research results suggested that ion implantation could become a promising approach for increasing phytoremediation efficiency of nutrients from eutrophic water by L. multiflorum.

  4. Low Energy Supersymmetry Phenomenology

    SciTech Connect

    Feng, J.

    2003-06-16

    We summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, we evaluate the capabilities of various e{sup +}e{sup -}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, we discuss capabilities of future facilities to dis-entangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. We comment upon the complementarity of proposed hadron and e{sup +}e{sup -} machines for a comprehensive study of low energy supersymmetry.

  5. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.; Feng, J.; Fujii, K.; Gunion, J.; Kamon, T.; Lopez, J.L.; Kao, C.

    1995-04-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. The authors then comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  6. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.

    1995-03-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{anti p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of superparticles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. They comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  7. Electron trapping in 4H-SiC MOS capacitors fabricated by pre-oxidation nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Basile, A. F.; Dhar, S.; Mooney, P. M.

    2011-06-01

    Incorporation of nitrogen (N) atoms by ion implantation prior to oxidation of SiO2/4H-SiC interfaces has been investigated by capacitance-voltage (C-V) characteristics and constant capacitance deep-level-transient spectroscopy (CCDLTS) measurements. The shift of the C-V curves to negative voltages can be explained by the partial activation of implanted N atoms during oxidation. The maximum amplitude of the CCDLTS spectra, proportional to the density of near-interface oxide traps, decreases with increasing N dose, but remains significantly larger than that of SiO2/SiC interfaces fabricated by post oxidation annealing in nitric oxide (NO). Intrinsic defects in the SiC epi-layer associated with implantation damage are also observed in N-implanted samples. In contrast, electron traps energetically close to the SiC conduction band, detected in NO annealed samples and presumably introduced during oxidation, are not observed in N-implanted samples. The improved transport characteristics of MOS transistors fabricated on N-implanted epi-layers compared to those fabricated by NO annealing is suggested to result from the effects of the greater N donor concentration and also possibly to the suppression of shallow electron traps in the SiC epilayer.

  8. Mechanical properties of nitrogen-rich surface layers on SS304 treated by plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Fernandes, B. B.; Mändl, S.; Oliveira, R. M.; Ueda, M.

    2014-08-01

    The formation of hard and wear resistant surface regions for austenitic stainless steel through different nitriding and nitrogen implantation processes at intermediate temperatures is an established technology. As the inserted nitrogen remains in solid solution, an expanded austenite phase is formed, accounting for these surface improvements. However, experiments on long-term behavior and exact wear processes within the expanded austenite layer are still missing. Here, the modified layers were produced using plasma immersion ion implantation with nitrogen gas and had a thickness of up to 4 μm, depending on the processing temperature. Thicker layers or those with higher surface nitrogen contents presented better wear resistance, according to detailed microscopic investigation on abrasion, plastic deformation, cracking and redeposition of material inside the wear tracks. At the same time, cyclic fatigue testing employing a nanoindenter equipped with a diamond ball was carried out at different absolute loads and relative unloadings. As the stress distribution between the modified layer and the substrate changes with increasing load, additional simulations were performed for obtaining these complex stress distributions. While high nitrogen concentration and/or thicker layers improve the wear resistance and hardness, these modifications simultaneously reduce the surface fatigue resistance.

  9. LOW ENERGY COUNTING CHAMBERS

    DOEpatents

    Hayes, P.M.

    1960-02-16

    A beta particle counter adapted to use an end window made of polyethylene terephthalate was designed. The extreme thinness of the film results in a correspondingly high transmission of incident low-energy beta particles by the window. As a consequence, the counting efficiency of the present counter is over 40% greater than counters using conventional mica end windows.

  10. Nanoarchitectured Co-Cr-Mo orthopedic implant alloys: nitrogen-enhanced nanostructural evolution and its effect on phase stability.

    PubMed

    Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

    2013-04-01

    Our previous studies indicate that nitrogen addition suppresses the athermal γ (face-centered cubic, fcc)→ε (hexagonal close-packed, hcp) martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the present study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced γ phase stability due to nitrogen addition. Alloy specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase γ matrix, whereas the N-free alloys had a γ/ε duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. This indicates that nitrogen has little effect on the stability of the γ phase, which is also predicted by thermodynamic calculations. We discovered short-range ordering (SRO) or nanoscale Cr2N precipitates in the γ matrix of the N-containing alloy specimens, and it was revealed that both SRO and nanoprecipitates function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the γ→ε martensitic transformation. Since the formation of ε martensite plays a crucial role in plastic deformation and wear behavior, the developed nanostructural modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

  11. Interaction between Low Energy Ions and the Complicated Organism

    NASA Astrophysics Data System (ADS)

    Yu, Zeng-liang

    1999-12-01

    Low energy ions exist widely in natural world, but people pay a little attention on the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in chemical synthesis of the biomolecules and application in genetic modification.

  12. Hemocompatibility of nitrogen-doped, hydrogen-free diamond-like carbon prepared by nitrogen plasma immersion ion implantation-deposition.

    PubMed

    Kwok, Sunny C H; Yang, Ping; Wang, Jin; Liu, Xuanyong; Chu, Paul K

    2004-07-01

    Amorphous hydrogenated carbon (a-C:H) has been shown to be a potential material in biomedical devices such as artificial heart valves, bone implants, and so on because of its chemical inertness, low coefficient of friction, high wear resistance, and good biocompatibility. However, the biomedical characteristics such as blood compatibility of doped hydrogen-free diamond-like carbon (DLC) have not been investigated in details. We recently began to investigate the potential use of nitrogen-doped, hydrogen-free DLC in artificial heart valves. In our experiments, a series of hydrogen-free DLC films doped with nitrogen were synthesized by plasma immersion ion implantation-deposition (PIII-D) utilizing a pulsed vacuum arc plasma source and different N to Ar (FN/FAr) gas mixtures in the plasma chamber. The structures and properties of the film were evaluated by Raman spectroscopy, Rutherford backscattering spectrometry (RBS), and X-ray photoelectron spectroscopy (XPS). To assess the blood compatibility of the films and the impact on the blood compatibility by the presence of nitrogen, platelet adhesion tests were conducted. Our results indicate that the blood compatibility of both hydrogen-free carbon films (a-C) and amorphous carbon nitride films are better than that of low-temperature isotropic pyrolytic carbon (LTIC). The experimental results are consistent with the relative theory of interfacial energy and surface tension including both dispersion and polar components. Our results also indicate that an optimal fraction of sp2 bonding is desirable, but an excessively high nitrogen concentration degrades the properties to an extent that the biocompatibility can be worse than that of LTIC.

  13. Low-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ludhova, Livia

    2016-05-01

    There exist several kinds of sources emitting neutrinos in the MeV energy range. These low-energy neutrinos from different sources can be often detected by the same multipurpose detectors. The status-of-art of the field of solar neutrinos, geoneutrinos, and the search for sterile neutrino with artificial neutrino sources is provided here; other neutrino sources, as for example reactor or high-energy neutrinos, are described elsewhere. For each of these three fields, the present-day motivation and open questions, as well as the latest experimental results and future perspectives are discussed.

  14. Wear of UHMWPE against nitrogen-ion-implanted and NbN-coated Co-Cr-Mo alloy formed by plasma immersion ion implantation and deposition for artificial joints

    NASA Astrophysics Data System (ADS)

    Park, Won-Woong; Kim, Eun-Kyeom; Jeon, Jun-Hong; Choi, Jin-Young; Moon, Sun-Woo; Lim, Sang-Ho; Han, Seung-Hee

    2012-08-01

    NbN thin film was deposited on the Co-Cr-Mo alloy by plasma immersion ion implantation and deposition (PIII&D) to reduce the volume wear rate of UHMWPE. In addition, nitrogen ions were implanted on the surface of the Co-Cr-Mo alloy prior to the NbN film deposition in order to increase the hardness of the substrate. XPS analysis revealed that nitrogen ions were implanted into the surface of the Co-Cr-Mo alloy, leading to the formation of CrN and Cr2N. The UHMWPE volume wear rate was measured using a pin-on-disk tribometer. The wear test result showed that the volume wear rate of UHMWPE against NbN-coated Co-Cr-Mo alloy declined by 20% as compared to that in the untreated Co-Cr-Mo alloy. In addition, the UHMWPE wear rate against the nitrogen-ion-implanted and NbN-coated Co-Cr-Mo alloy could be drastically reduced by up to 48%. It can be concluded that a combination of prior nitrogen ion implantation and NbN coating via PIII&D is a promising surface treatment tool for extending the lifetime of metal-on-polymer artificial joints.

  15. Towards Low Energy Atrial Defibrillation.

    PubMed

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  16. Towards Low Energy Atrial Defibrillation

    PubMed Central

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  17. Polycrystalline silicon thin-film transistor with nickel-titanium oxide by sol-gel spin-coating and nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Wu, Shih-Chieh; Hou, Tuo-Hung; Chuang, Shiow-Huey; Chou, Hsin-Chih; Chao, Tien-Sheng; Lei, Tan-Fu

    2012-12-01

    This study demonstrates polycrystalline silicon thin-film transistors (poly-Si TFTs) integrated with a high-κ nickel-titanium oxide (NiTiO3) gate dielectric using sol-gel spin-coating and nitrogen channel implantation. This novel fabrication method of the high-κ NiTiO3 gate dielectric offers thin equivalent-oxide thickness and high gate capacitance density, favorable for increasing the current driving capability. Introducing nitrogen ions into the poly-Si using implantation effectively passivates the trap states not only in the poly-Si channel but also at the gate dielectric/poly-Si interface. The poly-Si NiTiO3 TFTs with nitrogen implantation exhibit significantly improved electrical characteristics, including lower threshold voltage, a steeper subthreshold swing, higher field-effect mobility, a larger on/off current ratio, and less threshold-voltage roll-off. Furthermore, the nitrogen implantation improves the reliability of poly-Si NiTiO3 TFTs against hot-carrier stress and positive bias temperature instability.

  18. Nitrogen

    USGS Publications Warehouse

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  19. Study of non-linear Hall effect in nitrogen-grown ZnO microstructure and the effect of H{sup +}-implantation

    SciTech Connect

    Kumar, Yogesh Bern, Francis; Barzola-Quiquia, Jose; Lorite, Israel; Esquinazi, Pablo

    2015-07-13

    We report magnetotransport studies on microstructured ZnO film grown by pulsed laser deposition in N{sub 2} atmosphere on a-plane Al{sub 2}O{sub 3} substrates and the effect of low energy H{sup +}-implantation. Non-linearity has been found in the magnetic field dependent Hall resistance, which decreases with temperature. We explain this effect with a two-band model assuming the conduction through two different parallel channels having different types of charge carriers. Reduced non-linearity after H{sup +}-implantation in the grown film is due to the shallow-donor effect of hydrogen giving rise to an increment in the electron density, reducing the effect of the other channel.

  20. Effects of nitrogen-related defects on visible light photocatalytic response in N{sup +} implanted TiO{sub 2}: A first-principles study

    SciTech Connect

    Senga, Junya; Tatsumi, Kazuyoshi Muto, Shunsuke; Yoshida, Tomoko

    2015-09-21

    It was found that the visible-light responsiveness of a nitrogen ion-implanted TiO{sub 2} photocatalyst was attributable to the predominant chemical states of nitrogen, depending on the local nitrogen concentration near the surface. In the present study, we examined the effects of conceivable nitrogen-related defects on the visible light responsiveness, based on electronic structures calculated from first principles. Possible chemical states were proposed by comparing previously reported experiments with the present theoretical N-K X-ray absorption spectra. The theoretically predicted visible light absorption spectra and carrier trap states due to the bandgap states associated with the defects well explained the relationship between the catalytic reactivity and the proposed chemical states.

  1. A low energy electron magnetometer

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M., Jr.; Rayborn, G. H.; White, F. A.

    1979-01-01

    The concept of a highly sensitive magnetometer based on the deflection of low energy electron beams in magnetic fields is analyzed. Because of its extremely low mass and consequently high e/m ratio, a low energy electron is easily deflected in a magnetic field, thus providing a basis for very low field measurement. Calculations for a specific instrument design indicate that a low energy electron magnetometer (LEEM) can measure magnetic fields as low as 1000 nT. The anticipated performance of LEEM is compared with that of the existing high resolution magnetometers in selected applications. The fast response time of LEEM makes it especially attractive as a potential instrument for magnetic signature analysis in large engineering systems.

  2. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  3. Surface mechanical properties, corrosion resistance, and cytocompatibility of nitrogen plasma-implanted nickel-titanium alloys: a comparative study with commonly used medical grade materials.

    PubMed

    Yeung, K W K; Poon, R W Y; Chu, P K; Chung, C Y; Liu, X Y; Lu, W W; Chan, D; Chan, S C W; Luk, K D K; Cheung, K M C

    2007-08-01

    Stainless steel and titanium alloys are the most common metallic orthopedic materials. Recently, nickel-titanium (NiTi) shape memory alloys have attracted much attention due to their shape memory effect and super-elasticity. However, this alloy consists of equal amounts of nickel and titanium, and nickel is a well known sensitizer to cause allergy or other deleterious effects in living tissues. Nickel ion leaching is correspondingly worse if the surface corrosion resistance deteriorates. We have therefore modified the NiTi surface by nitrogen plasma immersion ion implantation (PIII). The surface chemistry and corrosion resistance of the implanted samples were studied and compared with those of the untreated NiTi alloys, stainless steel, and Ti-6Al-4V alloy serving as controls. Immersion tests were carried out to investigate the extent of nickel leaching under simulated human body conditions and cytocompatibility tests were conducted using enhanced green fluorescent protein mice osteoblasts. The X-ray photoelectron spectroscopy results reveal that a thin titanium nitride (TiN) layer with higher hardness is formed on the surface after nitrogen PIII. The corrosion resistance of the implanted sample is also superior to that of the untreated NiTi and stainless steel and comparable to that of titanium alloy. The release of nickel ions is significantly reduced compared with the untreated NiTi. The sample with surface TiN exhibits the highest amount of cell proliferation whereas stainless steel fares the worst. Compared with coatings, the plasma-implanted structure does not delaminate as easily and nitrogen PIII is a viable way to improve the properties of NiTi orthopedic implants.

  4. Low Energy Schools in Ireland

    ERIC Educational Resources Information Center

    Heffernan, Martin

    2004-01-01

    Out of a commitment to reducing carbon dioxide emissions, Ireland's Department of Education and Science has designed and constructed two low energy schools, in Tullamore, County Offaly, and Raheen, County Laois. With energy use in buildings responsible for approximately 55% of the CO[subscript 2] released into the atmosphere and a major…

  5. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    NASA Astrophysics Data System (ADS)

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-05-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2.

  6. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    Ammonia was produced by 12 companies at 27 plants in 15 states in the United States during 2011. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2011, U.S. producers operated at about 84 percent of their rated capacity (excluding plants that were idle for the entire year). Four companies — CF Industries Holdings Inc.; Koch Nitrogen Co.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 77 percent of the total U.S. ammonia production capacity.

  7. The Low Energy Neutrino Factory

    SciTech Connect

    Bross, Alan; Geer, Steve; Ellis, Malcolm; Fernandez Martinez, Enrique; Li, Tracey; Pascoli, Silvia; Mena, Olga

    2010-03-30

    We show that a low energy neutrino factory with a baseline of 1300 km and muon energy of 4.5 GeV has an excellent physics reach. The results of our optimisation studies demonstrate that such a setup can have remarkable sensitivity to theta{sub 13} and delta for sin{sup 2}(2theta{sub 13})>10{sup -4}, and to the mass hierarchy for sin{sup 2}(2theta{sub 13})>10{sup -3}. We also illustrate the power of the unique combination of golden and platinum channels accessible to the low energy neutrino factory. We have considered both a 20 kton totally active scintillating detector and a 100 kton liquid argon detector as possible detector technologies, finding that a liquid argon detector with very good background rejection can produce sensitivity to theta{sub 13} and delta with that of the International Design Study neutrino factory.

  8. The low energy signaling network

    PubMed Central

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments. PMID:25101105

  9. The low energy signaling network.

    PubMed

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-Llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments.

  10. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Ammonia is the principal source of fixed nitrogen. It was produced by 17 companies at 34 plants in the United States during 2003. Fifty-three percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock.

  11. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  12. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  13. Improvements of anti-corrosion and mechanical properties of NiTi orthopedic materials by acetylene, nitrogen and oxygen plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Poon, Ray W. Y.; Ho, Joan P. Y.; Liu, Xuanyong; Chung, C. Y.; Chu, Paul K.; Yeung, Kelvin W. K.; Lu, William W.; Cheung, Kenneth M. C.

    2005-08-01

    Nickel-titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C2H2 PIII is composed of mainly TiCx with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti4+, Ti3+ and Ti2+.

  14. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  15. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation.

    PubMed

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F; Wang, Jian-Ping

    2016-05-05

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 10(7) erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25-30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 10(17)/cm(2).

  16. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    PubMed Central

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-01-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2. PMID:27145983

  17. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation.

    PubMed

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F; Wang, Jian-Ping

    2016-01-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 10(7) erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25-30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 10(17)/cm(2). PMID:27145983

  18. Low-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; ACE/CRIS Collaboration

    2002-12-01

    Cosmic rays with energies below about 10 GeV/nucleon have been measured with high precision as a result of experiments on the HEAO, Ulysses, and ACE spacecrafts. The observations provide energy spectra, elemental abundances, and isotopic composition for elements up through Z=30. They include both stable and radioactive nuclides that are synthesized in stars or are produced by nuclear fragmentation during diffusion at high energies through interstellar medium. From these data one obtains a rather detailed picture of the origin of low-energy cosmic rays. For refractory species, the cosmic-ray source composition closely resembles that of the Sun, suggesting that cosmic rays are accelerated from a well-mixed sample of interstellar matter. A chemical fractionation process has depleted the abundances of volatile elements relative to refractories. Using various radioactive clock isotopes it has been shown that particle acceleration occurs at least 105 years after supernova nucleosynthesis and that the accelerated particles diffuse in the Galaxy for approximately 15 Myr after acceleration. Energy spectra and secondary-to-primary ratios are reasonably well accounted for by models in which particles gain the bulk of their energy in a single encounter with a strong shock. Among the large number of species that have been measured, 22Ne stands out as the only nuclide with an abundance that is clearly much different than solar. To test models proposed to account for this anomaly, the data are being analyzed for predicted smaller effects on abundances of other nuclides. In addition to providing a detailed understanding of the origin and acceleration of low-energy cosmic rays, these data are providing constraints on the chemical evolution of interstellar matter. This work was supported by NASA at Caltech (under grant NAG5-6912), JPL, NASA/GSFC, and Washington U.

  19. Production of [15O]Water at Low-Energy Proton Cyclotrons

    SciTech Connect

    Powell, James; O'Neil, James P.

    2005-12-12

    We report a simple system for producing [15O]H2O from nitrogen-15 in a nitrogen/hydrogen gas target with recycling of the target nitrogen, allowing production on low-energy proton-only accelerators with minimal consumption of isotopically enriched nitrogen-15. The radiolabeled water is separated from the target gas and radiolytically produced ammonia by temporary freezing in a small trap at -40 C.

  20. Effects of simultaneous boron and nitrogen implantation on microhardness and fatigue properties of Fe-13cr-15ni alloys

    NASA Astrophysics Data System (ADS)

    Rao, G. R.; Lee, E. H.; Chin, B. A.; Mansur, L. K.

    1994-12-01

    Eight complex austenitic stainless steel alloys based on the composition Fe-13Cr-15Ni-2Mo-2Mn-0.2Ti-0.8Si-0.06C were implanted simultaneously with 400-keV B+ and 550-keV N+ ions and were investigated for changes in fatigue properties and surface microhardness. The nearsurface hardness of all eight alloys improved, but the fatigue life of each decreased. These findings were contrary to those obtained in an earlier study using four simple Fe-13Cr-15Ni alloys, where the dual implantation improved fatigue life by up to 250 pct. While unimplanted specimens failed by slip-band crack initiation, it was hypothesized that the dual implantation suppressed slip to the extent that fewer slip-band cracks were initiated and these were subjected to accelerated crack propagation. In addition, grain-boundary cracking was promoted, yielding a lower fatigue life. Support for this hypothesis was obtained by a study of single crystals of Fe-15Cr-15Ni, which were also implanted with B+ and N+. The dual implantation caused a lower fatigue life due to concentration of slip along a few slip bands to relieve applied stress. Evidence of grain-boundary cracking was obtained using the four simple alloys, which were subjected to triple ion implantation with B+, N+, and C+. The triple implantation decreased the fatigue life of the alloys and caused accelerated growth of fewer slip bands and grain-boundary cracking due to suppression of surface slip bands. This study thus shows the existence of an optimum level of strengthening when multiple ion implantation is used to improve the fatigue properties of alloys.

  1. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  2. Low-Temperature Activation of Ion-Implanted Boron and Nitrogen Ions in Cd x Hg1- x Te Heteroepitaxial Layers

    NASA Astrophysics Data System (ADS)

    Voitsekhovskii, A. V.; Talipov, N. Kh.

    2013-12-01

    Processes of electrical activation of ion-implanted boron and nitrogen atoms in Cd x Hg1- x Te (CMT) heteroepitaxial layers grown by methods of molecular-beam epitaxy (HEL CMT MBE) and liquid-phase epitaxy (LPE CMT) have been investigated; likewise in bulk crystals of CMT with low-temperature annealings under anodic oxide. The possibility has been demonstrated of using anodic oxide as an efficient mask for postimplantation annealings of p-type HEL CMT MBE in the temperature interval Т = 200-250°C without disruption of the composition of the variband layer or alteration of the electrophysical properties of the structure. It has been established that in HEL CMT MBE the efficiency of activation of boron as a slowly diffusing donor impurity is lowered with growth of the dose of the B+ ions and is increased by thermal cycling from Т = 77 K to room temperature. Implanted nitrogen, in contrast to boron, is a rapidly diffusing acceptor impurity in CMT, efficiently compensating both radiation donor centers and activated boron. The degree of electrical activation of nitrogen grows substantially upon thermal cycling. It has been shown that the mobility spectrum is an efficient method for monitoring the process of electrical activation of boron in p-type HEL CMT MBE. Mesa photodiodes based on activated boron in p-type HEL CMT MBE with long-wavelength photosensitivity boundary λc = 11 μm, prepared here for the first time, had a high maximum value of the product of the differential resistance by the area of the photodiode R d A = (6 - 8)ṡ102 Ωṡcm2, product R 0 A = 5 - 6 Ωṡcm2 (at zero bias), and a diffusion ledge on the inverse branch of the current-voltage ( I- V) characteristic out to a bias voltage of 1.3 V.

  3. Low-Energy Sputtering Research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1999-01-01

    An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

  4. Influence of nitrogen ion implantation on filtration of fluoride and cadmium using polysulfone/chitosan blend membranes

    NASA Astrophysics Data System (ADS)

    Wanichapichart, P.; Bootluck, W.; Thopan, P.; Yu, L. D.

    2014-05-01

    Composite membranes between polysulfone and biopolymer chitosan were produced with variations of the chitosan content and temperature during the phase inversion process. The lower chitosan content led to lower water permeability and smaller membrane cut off. When the temperature of the phase inversion process was reduced from 25 °C to 5 °C, membrane pores were further decreased from somewhat greater than 10 kDa to a value smaller than 2 kDa. After being implanted with N-ions of 50 keV to a fluence of 1 × 1015 ions/cm2, the composite membranes showed an improvement in the rejection by about 15% for fluoride and 10% for cadmium. In addition, a slight increase in permeation flux was observed in the ion implanted membranes. Filtration tests using the N-ion implanted membranes showed that fluoride was rejected from 100 ppm NaF solution by 47% and the rejection was increased to 60% when 2.20 ppm underground water was filtered. In the case of cadmium, the rejection was increased from 80% to 90% as an effect of the N-ion implantation.

  5. Effect of nitrogen ion implantation on corrosion inhibition of nickel coated 316 stainless steel and correlation with nano-structure

    NASA Astrophysics Data System (ADS)

    Grayeli-Korpi, Ali-Reza; Savaloni, Hadi

    2012-10-01

    The influence of implantation of N+ with 20 keV energy and different fluences in the range of 1 × 1017 and 5 × 1018 ions/cm2 in the nickel coated type 316 stainless steel (SS) on the corrosion inhibition of SS in 3.5 wt% NaCl solution is investigated. The highest available N+ fluence showed highest corrosion inhibition. X-ray diffraction (XRD) analysis showed formation of nickel nitride phases that enhanced by increasing the N+ fluence. Surface morphology was studied by atomic force microscope (AFM) and scanning electron microscope (SEM) before and after corrosion test, respectively. AFM results showed that by increasing N+ fluence surface of the sample becomes smoother that may be the result of heat accumulation during implantation causing higher rate of diffusion in the sample.

  6. Low-energy nuclear physics with high-segmentation silicon arrays

    SciTech Connect

    Betts, R.R. |

    1994-12-01

    A brief history is given of silicon detectors leading up to the development of ion-implanted strip detectors. Two examples of their use in low energy nuclear physics are discussed; the search for exotic alpha-chain states in {sup 24}Mg and studies of anomalous positron-electron pairs produced in collisions of very heavy ions.

  7. Surface and bulk-loss reduction research by low-energy hydrogen doping

    NASA Technical Reports Server (NTRS)

    Fonash, S.

    1985-01-01

    Surface and bulk loss reduction by low energy hydrogen doping of silicon solar cells was examined. Hydrogen ions provided a suppression of space charge recombination currents. Implantation of hydrogen followed by the anneal cycle caused more redistribution of boron than the anneal which could complicate processing. It was demonstrated that passivation leads to space charge current reduction.

  8. Low energy ghosts and the Jeans' instability

    NASA Astrophysics Data System (ADS)

    Gümrükçüoǧlu, A. Emir; Mukohyama, Shinji; Sotiriou, Thomas P.

    2016-09-01

    We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradient is spacelike. By performing a canonical transformation we demonstrate that this low energy ghost can be recast, at the level of the action, in a form of a fluid that undergoes a Jeans-like instability affecting only modes with large wavelength. This illustrates that low energy tachyonic ghosts do not lead to a catastrophic quantum vacuum instability, unlike the usual high-energy ghost degrees of freedom.

  9. Solar-assisted low energy dwellings

    SciTech Connect

    Esbensen, T V

    1980-02-01

    The Zero Energy House Group was formed as a subproject of the CCMS Solar Energy Pilot Study in 1974 by seven participating countries experimenting with solar-assisted low-energy dwellings for temperate and northern European climatic conditions. A Zero Energy House is one in which solar energy is used to meet the reduced energy needs of buildings incorporating various thermal energy conservation features. This final report of the Zero Energy House Group includes brief descriptions of 13 major low-energy dwellings in the participating CCMS countries. An overall assessment of the state-of-the-art in solar-assisted low-energy dwellings is also included.

  10. The Science of Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Storms, Edmund

    2007-03-01

    The large literature describing the anomalous behavior attributed to cold fusion or low energy nuclear reactions has been critically described in a recently published book. Over 950 publications are evaluated allowing the phenomenon to be understood. A new class of nuclear reactions has been discovered that are able to generate practical energy without significant radiation or radioactivity. Edmund K Storms, The Science of Low Energy Nuclear Reactions, in press (2006). Also see: http://www.lenr-canr.org/StudentsGuide.htm .

  11. Production of [15O]water at low-energy proton cyclotrons.

    PubMed

    Powell, J; O'Neil, J P

    2006-07-01

    We report a simple system for producing [15O]H2O from 15N in a nitrogen/hydrogen gas target with recycling of the target nitrogen, allowing production on low-energy proton-only accelerators with minimal consumption of isotopically enriched 15N. The radiolabeled water is separated from the target gas and radiolytically produced ammonia by temporary freezing in a small trap at -40 degrees C.

  12. Low-energy electron-induced reactions in condensed matter

    NASA Astrophysics Data System (ADS)

    Arumainayagam, Christopher R.; Lee, Hsiao-Lu; Nelson, Rachel B.; Haines, David R.; Gunawardane, Richard P.

    2010-01-01

    The goal of this review is to discuss post-irradiation analysis of low-energy (≤50 eV) electron-induced processes in nanoscale thin films. Because electron-induced surface reactions in monolayer adsorbates have been extensively reviewed, we will instead focus on low-energy electron-induced reactions in multilayer adsorbates. The latter studies, involving nanoscale thin films, serve to elucidate the pivotal role that the low-energy electron-induced reactions play in high-energy radiation-induced chemical reactions in condensed matter. Although electron-stimulated desorption (ESD) experiments conducted during irradiation have yielded vital information relevant to primary or initial electron-induced processes, we wish to demonstrate in this review that analyzing the products following low-energy electron irradiation can provide new insights into radiation chemistry. This review presents studies of electron-induced reactions in nanoscale films of molecular species such as oxygen, nitrogen trifluoride, water, alkanes, alcohols, aldehydes, ketones, carboxylic acids, nitriles, halocarbons, alkane and phenyl thiols, thiophenes, ferrocene, amino acids, nucleotides, and DNA using post-irradiation techniques such as temperature-programmed desorption (TPD), reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), gel electrophoresis, and microarray fluorescence. Post-irradiation temperature-programmed desorption, in particular, has been shown to be useful in identifying labile radiolysis products as demonstrated by the first identification of methoxymethanol as a reaction product of methanol radiolysis. Results of post-irradiation studies have been used not only to identify radiolysis products, but also to determine the dynamics of electron-induced reactions. For example, studies of the radiolysis yield as a function of incident electron energy have shown that dissociative

  13. Tissue modeling schemes in low energy breast brachytherapy.

    PubMed

    Afsharpour, Hossein; Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank

    2011-11-21

    Breast tissue is heterogeneous and is mainly composed of glandular (G) and adipose (A) tissues. The proportion of G versus A varies considerably among the population. The absorbed dose distributions in accelerated partial breast irradiation therapy with low energy photon brachytherapy sources are very sensitive to tissue heterogeneities. Current clinical algorithms use the recommendations of the AAPM TG43 report which approximates the human tissues by unit density water. The aim of this study is to investigate various breast tissue modeling schemes for low energy brachytherapy. A special case of breast permanent seed implant is considered here. Six modeling schemes are considered. Uniform and non-uniform water breast (UWB and NUWB) consider the density but neglect the effect of the composition of tissues. The uniform and the non-uniform G/A breast (UGAB and NUGAB) as well the age-dependent breast (ADB) models consider the effect of the composition. The segmented breast tissue (SBT) method uses a density threshold to distinguish between G and A tissues. The PTV D(90) metric is used for the analysis and is based on the dose to water (D(90(w,m))). D(90(m,m)) is also reported for comparison to D(90(w,m)). The two-month post-implant D(90(w,m)) averaged over 38 patients is smaller in NUWB than in UWB by about 4.6% on average (ranging from 5% to 13%). Large average differences of G/A breast models with TG43 (17% and 26% in UGAB and NUGAB, respectively) show that the effect of the chemical composition dominates the effect of the density on dose distributions. D(90(w,m)) is 12% larger in SBT than in TG43 when averaged. These differences can be as low as 4% or as high as 20% when the individual patients are considered. The high sensitivity of dosimetry on the modeling scheme argues in favor of an agreement on a standard tissue modeling approach to be used in low energy breast brachytherapy. SBT appears to generate the most geometrically reliable breast tissue models in this

  14. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Carl R. Brune; Steven M. Grimes

    2010-01-13

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between March 1, 2006 and October 31, 2009 which were supported by U.S. DOE grant number DE-FG52-06NA26187.

  15. Parity violation in low-energy

    SciTech Connect

    Martin Savage

    2001-12-01

    Parity violation in low-energy nuclear observables is included in the pionless effective field theory. The model-independent relation between the parity-violating asymmetry in polarized np -> d gamma and the non-nucleon part of the deuteron anapole moment is discussed. The asymmetry in np -> d gamma computed with KSW power-counting, and recently criticized by Desplanques, is discussed.

  16. Enhanced retained dose uniformity in NiTi spinal correction rod treated by three-dimensional mesh-assisted nitrogen plasma immersion ion implantation

    SciTech Connect

    Lu, Q. Y.; Hu, T.; Kwok, Dixon T. K.; Chu, Paul K.

    2010-05-15

    Owing to the nonconformal plasma sheath in plasma immersion ion implantation of a rod sample, the retained dose can vary significantly. The authors propose to improve the implant uniformity by introducing a metal mesh. The depth profiles obtained with and without the mesh are compared and the implantation temperature at various locations is evaluated indirectly by differential scanning calorimeter. Our results reveal that by using the metal mesh, the retained dose uniformity along the length is greatly improved and the effects of the implantation temperature on the localized mechanical properties of the implanted NiTi shape memory alloy rod are nearly negligible.

  17. Effect of Implantation Machine Parameters on N+ ion Implantation for Upland Cotton(Gossypium hirsutum L.) Pollen

    NASA Astrophysics Data System (ADS)

    Yue, Jieyu; Yu, Lixiang; Wu, Yuejin; Tang, Canming

    2008-10-01

    Effect of parameters of ion implantation machine, including ion energy, total dose, dose rate, impulse energy and implantation interval on the pollen grains of upland cotton implanted with nitrogen ion beam were studied. The best parameters were screened out. The results also showed that the vacuum condition before the nitrogen ion implantation does not affect the pollen viability.

  18. Solar nitrogen - Evidence for a secular increase in the ratio of nitrogen-15 to nitrogen-14

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1975-01-01

    Solar wind nitrogen, implanted in lunar soil samples, exhibits isotopic variations that are related to the time, although not to the duration, of implantation, with earlier samples characterized by lower ratios of nitrogen-15 to nitrogen-14. An increase in the solar nitrogen-15 content during the lifetime of the lunar regolith is probably caused by spallation of oxygen-16 in the surface regions of the sun.-

  19. Entanglement creation in low-energy scattering

    SciTech Connect

    Weder, Ricardo

    2011-12-15

    We study the entanglement creation in the low-energy scattering of two particles in three dimensions, for a general class of interaction potentials that are not required to be spherically symmetric. The incoming asymptotic state, before the collision, is a product of two normalized Gaussian states. After the scattering, the particles are entangled. We take as a measure of the entanglement the purity of one of them. We provide a rigorous explicit computation, with error bound, of the leading order of the purity at low energy. The entanglement depends strongly on the difference of the masses. It takes its minimum when the masses are equal, and it increases rapidly with the difference of the masses. It is quite remarkable that the anisotropy of the potential gives no contribution to the leading order of the purity, in spite of the fact that entanglement is a second-order effect.

  20. Low energy ion loss at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S.; Liemohn, M.; Fang, X.; Ma, Y.

    2012-04-01

    Current data observations and modeling efforts have indicated that the low-energy pick-up ions on Mars significantly contribute to the overall escape rate. Due to the lack of a dipole magnetic field, the solar wind directly interacts with the dayside upper atmosphere causing particles to be stripped away. In this study, we use a 3-D Monte Carlo test particle simulation with virtual detectors to observe low energy ions (< 50 eV) in the Mars space environment. We will present velocity space distributions that can capture the asymmetric and non-gyrotropic features of particle motion. The effect of different solar conditions will also be discussed with respect to ion fluxes at various spatial locations as well as overall loss in order to robustly describe the physical processes controlling the distribution of planetary ions and atmospheric escape.

  1. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1985-01-01

    The author built and tested a low energy cyclotron for radiocarbon dating similar to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. The author found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. The author shows how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  2. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Δ V than a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun-Earth-Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.

  3. PHYSICS WITH ULTRA-LOW ENERGY ANTIPROTONS

    SciTech Connect

    M. HOLZSCHEITER

    2001-02-01

    In this report the author describes the current status of the antiproton deceleration (AD) facility at CERN, and highlights the physics program with ultra-low energy antiproton at this installation. He also comments on future possibilities provided higher intensity antiproton beams become available at Fermilab, and review possibilities for initial experiments using direct degrading of high energy antiprotons in material has been developed and proven at CERN.

  4. Seesaw scale from low-energy parameters

    SciTech Connect

    He Xiaogang

    2012-07-27

    Seesaw models can provide explanations why neutrino are so much lighter than their charged partners. However, A priori, the seesaw scale is not determined. In this talk, I report work published in Ref.[1] by Law, Volkas and myself which shows that it is possible to construct theoretical models where the seesaw scale is completely determined in terms of low-energy fermion mass, mixing angles and CP-violating phases observable quantities.

  5. Targeting Low-Energy Ballistic Lunar Transfers

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  6. Low-energy electron interactions with biomolecules

    NASA Astrophysics Data System (ADS)

    Winstead, Carl

    2012-06-01

    Low-energy electron interactions with biomolecules have been the focus of sustained attention over the past decade. The demonstration by Sanche and coworkers that even subexcitation and subionization electrons can induce strand breaks in DNA opened a new frontier in understanding radiation damage to living systems. Many studies of DNA subunits and their analogues, both experimental and theoretical, have elucidated likely mechanisms by which slow electrons attach to and disrupt DNA, although the full picture is far from clear and some elements of it remain controversial. Increasing attention is also being given to low-energy electron collisions with amino acids in order to explore possible mechanisms of electron-mediated radiation damage to proteins. In a completely different context, electron-biomolecule collisions are fundamental to spark ignition and cumbustion of biofuels such as methanol and ethanol. Not to be overlooked, either, is the simplest but most ubiquitous biomolecule of all, water, whose low-energy electron cross sections remain surprisingly ill-characterized. This talk will survery recent ab initio computational studies using the Schwinger multichannel method of DNA- and protein-related molecules, alcohols, and water. Much of the work to be presented was carried out in collaboration with experimentalists who undertook complementary measurements, allowing for useful comparisons to be made. Although the primary focus will be on electronically elastic collisions relevant to dissociative attachment and electron transport, electron-impact excitation cross sections for water will be presented and discussed.

  7. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  8. Low-energy proton capture reactions

    SciTech Connect

    Lipoglavsek, M.; Cvetinovic, A.; Gajevic, J.; Likar, A.; Vavpetic, P.; Petrovic, T.

    2014-05-09

    An overview of experimental problems in measuring the cross sections for (p,γ) and (p,n) reactions at low energies is given with a specific emphasis on electron screening in metallic targets. Thick target γ-ray and neutron yields are compared for Ni and NiO targets, V and VO{sub 2} targets and Mn and MnO targets. The {sup 1}H({sup 7}Li,α){sup 4}He reaction was studied in inverse kinematics with hydrogen loaded into Pd and PdAg alloy foils from gas phase. Based on these results, a new approach to electron screening in nuclear reactions is suggested.

  9. Low energy fission: dynamics and scission configurations

    NASA Astrophysics Data System (ADS)

    Goutte, H.; Berger, J.-F.; Gogny, D.; Younes, W.

    2005-11-01

    In the first part of this paper we recall a recent study concerning low energy fission dynamics. Propagation is made by use of the Time Dependent Generator Coordinate Method, where the basis states are taken from self-consistent Hartree-Fock-Bogoliubov calculations with the Gogny force. Theoretical fragment mass distributions are presented and compared with the evaluation made by Wahl. In the second part of this paper, new results concerning scission configurations are shown. Deviations of the fission fragment proton numbers from the Unchanged Charge Distribution prescription and fission fragment deformations are discussed.

  10. FLSR - The Frankfurt low energy storage ring

    NASA Astrophysics Data System (ADS)

    Stiebing, K. E.; Alexandrov, V.; Dörner, R.; Enz, S.; Kazarinov, N. Yu.; Kruppi, T.; Schempp, A.; Schmidt Böcking, H.; Völp, M.; Ziel, P.; Dworak, M.; Dilfer, W.

    2010-02-01

    An electrostatic storage ring for low-energy ions with a design energy of 50 keV is presently being set up at the Institut für Kernphysik der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany (IKF). This new device will provide a basis for new experiments on the dynamics of ionic and molecular collisions, as well as for high precision and time resolved laser spectroscopy. In this article, the design parameters of this instrument are reported.

  11. The low energy booster project status

    SciTech Connect

    Tuttle, G.W.

    1993-05-01

    In order to achieve the required injection momentum, the Superconducting Super Collider (SSC) has an accelerator chain comprised of a Linear Accelerator and three synchrotrons. The Low Energy Booster (LEB) is the first synchrotron in this chain. The LEB project has made significant progress in the development of major subsystems and conventional construction. This paper briefly reviews the performance requirements of the LEB and describes significant achievements in each of the major subsystem areas. Highlighted among these achievements are the LEB foreign collaborations with the Budker Institute of Nuclear Physics (BINP) located in Novosibirsk, Russia.

  12. Low energy signatures of nonlocal field theories

    NASA Astrophysics Data System (ADS)

    Belenchia, Alessio; Benincasa, Dionigi M. T.; Martín-Martínez, Eduardo; Saravani, Mehdi

    2016-09-01

    The response of inertial particle detectors coupled to a scalar field satisfying nonlocal dynamics described by nonanalytic functions of the d'Alembertian operator □ is studied. We show that spontaneous emission processes of a low energy particle detector are very sensitive to high-energy nonlocality scales. This allows us to suggest a nuclear physics experiment (˜MeV energy scales) that outperforms the sensitivity of LHC experiments by many orders of magnitude. This may have implications for the falsifiability of theoretical proposals of quantum gravity.

  13. The Telescope Array's Low Energy Extension: TALE

    NASA Astrophysics Data System (ADS)

    Matthews, John

    2009-05-01

    A great deal of information about the sources of ultra high energy cosmic rays exists encoded in the energy spectrum. There are three spectral features in the ultra high energy regime (the second knee, the ankle, and the GZK cut-off). An important composition change also occurs in this energy range. The Telescope Array (TA) is a large area ultra high energy cosmic ray observatory built and operated by groups from the US, Japan, Korea, and Russia. The existing part of the Telescope Array already has good efficiency above the ankle (˜10^18.5 eV). These detectors are already in the field collecting data. The TA Low Energy Extension (TALE) refers to the detectors devoted to the ``low energy'' portion of the spectrum - 10^16.5 - 10^19 eV. The aim of TA/TALE is to understand the origin of cosmic rays and to study their composition over a broad energy range. We will introduce the detector components and discuss the opportunities.

  14. Low Energy Ion-Molecule Reactions

    SciTech Connect

    James M. Farrar

    2004-05-01

    This objective of this project is to study the dynamics of the interactions of low energy ions important in combustion with small molecules in the gas phase and with liquid hydrocarbon surfaces. The first of these topics is a long-standing project in our laboratory devoted to probing the key features of potential energy surfaces that control chemical reactivity. The project provides detailed information on the utilization of specific forms of incident energy, the role of preferred reagent geometries, and the disposal of total reaction energy into product degrees of freedom. We employ crossed molecular beam methods under single collision conditions, at collision energies from below one eV to several eV, to probe potential surfaces over a broad range of distances and interaction energies. These studies allow us to test and validate dynamical models describing chemical reactivity. Measurements of energy and angular distributions of the reaction products with vibrational state resolution provide the key data for these studies. We employ the crossed beam low energy mass spectrometry methods that we have developed over the last several years.

  15. Low Energy Nuclear Reactions: 2007 Update

    NASA Astrophysics Data System (ADS)

    Krivit, Steven B.

    2007-03-01

    This paper presents an overview of low energy nuclear reactions, a subset of the field of condensed matter nuclear science. Condensed matter nuclear science studies nuclear effects in and/or on condensed matter, including low energy nuclear reactions, an entirely new branch of science that gained widespread attention and notoriety beginning in 1989 with the announcement of a previously unrecognized source of energy by Martin Fleischmann and Stanley Pons that came to be known as cold fusion. Two branches of LENR are recognized. The first includes a set of reactions like those observed by Fleischmann and Pons that use palladium and deuterium and yield excess heat and helium-4. Numerous mechanisms have been proposed to explain these reactions, however there is no consensus for, or general acceptance of, any of the theories. The claim of fusion is still considered speculative and, as such, is not an ideal term for this work. The other branch is a wide assortment of nuclear reactions that may occur with either hydrogen or deuterium. Anomalous nuclear transmutations are reported that involve light as well as heavy elements. The significant questions that face this field of research are: 1) Are LENRs a genuine nuclear reaction? 2) If so, is there a release of excess energy? 3) If there is, is the energy release cost-effective?

  16. Low energy neutrinos in Super-Kamiokande

    NASA Astrophysics Data System (ADS)

    Sekiya, Hiroyuki

    2016-05-01

    Super-Kamiokande (SK), a 50 kton water Cherenkov detector, observes 8B solar neutrinos via neutrino-electron elastic scattering. The analysis threshold was successfully lowered to 3.5 MeV (recoil electron kinetic energy) in SK-IV. To date SK has observed solar neutrinos for 18 years. An analysis regarding possible correlations between the solar neutrino flux and the 11 year solar activity cycle is shown. With large statistics, SK searches for distortions of the solar neutrino energy spectrum caused by the MSW resonance in the core of the sun. SK also searches for a day/night solar neutrino flux asymmetry induced by the matter in the Earth. The Super-Kamiokande Gd (SK-Gd) project is the upgrade of the SK detector via the addition of water-soluble gadolinium (Gd) salt. This modification will enable it to efficiently identify low energy anti-neutrinos. SK-Gd will pursue low energy physics currently inaccessible to SK due to backgrounds. The most important will be the world’s first observation of the diffuse supernova neutrino background. The main R&D program towards SK-Gd is EG ADS: a 200 ton, fully instrumented tank built in a new cavern in the Kamioka mine.

  17. Performance monitoring of low energy house, Macclesfield

    NASA Astrophysics Data System (ADS)

    Stephen, F. R.

    1980-01-01

    The monitoring of the energy balance of a very well insulated low-energy house in Macclesfield, England is discussed. The house is an existing dwelling which had been converted into a low-energy-requiring house by the reduction of heat loss through a high level of thermal insulation and the collection of solar energy by a water cascade solar panel with warm water storage. Measurements of house temperatures, radiation, off-peak electricity consumption and hot water and heating using were performed from January to August, 1978 and reveal that the house used less than 22,000 kWh electricity during that period, compared to 55,000 kWh expected if the house had been constructed to average insulation levels. Solar energy is found to contribute only 2% of house energy requirements, with the use of a heat pump combined with the solar panel leading to greater efficiency and thus utilization. In addition, the large thermal mass and good insulation are found to improve comfort by reducing temperature fluctuations, and the ventilation and low-temperature water return system employed provided satisfactory results.

  18. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  19. First-principles study on the interaction of nitrogen atom with α–uranium: From surface adsorption to bulk diffusion

    SciTech Connect

    Su, Qiulei; Deng, Huiqiu E-mail: hqdeng@gmail.com; Xiao, Shifang; Li, Xiaofan; Hu, Wangyu; Ao, Bingyun; Chen, Piheng

    2014-04-28

    Experimental studies of nitriding on uranium surfaces show that the modified layers provide considerable protection against air corrosion. The bimodal distribution of nitrogen is affected by both its implantation and diffusion, and the diffusion of nitrogen during implantation is also governed by vacancy trapping. In the present paper, nitrogen adsorption, absorption, diffusion, and vacancy trapping on the surface of and in the bulk of α–uranium are studied with a first-principles density functional theory approach and the climbing image nudged elastic band method. The calculated results indicate that, regardless of the nitrogen coverage, a nitrogen atom prefers to reside at the hollow1 site and octahedral (Oct) site on and below the surface, respectively. The lowest energy barriers for on-surface and penetration diffusion occur at a coverage of 1/2 monolayer. A nitrogen atom prefers to occupy the Oct site in bulk α–uranium. High energy barriers are observed during the diffusion between neighboring Oct sites. A vacancy can capture its nearby interstitial nitrogen atom with a low energy barrier, providing a significant attractive nitrogen-vacancy interaction at the trapping center site. This study provides a reference for understanding the nitriding process on uranium surfaces.

  20. Effects of Ion Implantation on in Vitro Pollen Germination and Cellular Organization of Pollen Tube in Pinus thunbergii Parl. (Japanese Black Pine)

    NASA Astrophysics Data System (ADS)

    Li, Guoping; Huang, Qunce; Yang, Lusheng; Dai, Ximei; Qin, Guangyong; Huo, Yuping

    2006-09-01

    Low-energy ion implantation, as a new technology to produce mutation in plant breeding, has been widely applied in agriculture in China. But so far there is a little understanding of the underlying mechanisms responsible for its biological effects at the cellular level. Here we report the biological effects of a nitrogen ion beams of 30 keV on the pollen grains of Pinus thunbergii Parl. In general, ion implantation inhibited pollen germination. The dose-response curve presented a particular saddle-like pattern. Ion implantation also changed the dimension of the elongated tubes and significantly induced tip swelling. Confocal microscopy indicated that the pollen tube tips in P. thunbergii contained an enriched network of microtubules. Ion implantation led to the disruption of microtubules especially in swollen tips. Treatment with colchicine demonstrated that tip swelling was caused by the disruption of microtubules in the tip, indicating a unique role for microtubules in maintaining the tip integrality of the pollen tube in conifer. Our results suggest that ion implantation induce the disruption of microtubule organization in pollen and pollen tubes and subsequently cause morphological abnormalities in the pollen tubes. This study may provide a clue for further investigation on the interaction between low-energy ion beams and pollen tube growth.

  1. Low Energy Antiproton Experiments - A Review

    SciTech Connect

    Jungmann, Klaus P.

    2005-10-19

    Low energy antiprotons offer excellent opportunities to study properties of fundamental forces and symmetries in nature. Experiments with them can contribute substantially to deepen our fundamental knowledge in atomic, nuclear and particle physics. Searches for new interactions can be carried out by studying discrete symmetries. Known interactions can be tested precisely and fundamental constants can be extracted from accurate measurements on free antiprotons (p-bar's) and bound two- and three-body systems such as antihydrogen (H-bar = p-bare-), the antprotonic helium ion (He++p-bar)+ and the antiprotonic atomcule (He++p-bare-) . The trapping of a single p-bar in a Penning trap, the formation and precise studies of antiprotonic helium ions and atoms and recently the production of H-bar have been among the pioneering experiments. They have led already to precise values for p-bar parameters, accurate tests of bound two- and three-body Quantum Electrodynamics (QED), tests of the CPT theorem and a better understanding of atom formation from their constituents. Future experiments promise more precise tests of the standard theory and have a robust potential to discover new physics. Precision experiments with low energy p-bar's share the need for intense particle sources and the need for time to develop novel instrumentation with all other experiments, which aim for high precision in exotic fundamental systems. The experimental programs - carried out in the past mostly at the former LEAR facility and at present at the AD facility at CERN - would benefit from intense future sources of low energy p-bar's. The highest possible p-bar fluxes should be aimed for at new facilities such as the planned FLAIR facility at GSI in order to maximize the potential of delicate precision experiments to influence model building. Examples of key p-bar experiments are discussed here and compared with other experiments in the field. Among the central issues is their potential to obtain

  2. Phenomenological implications of low energy supersymmetry breaking

    SciTech Connect

    Dimopoulos, S. |; Dine, M.; Raby, S.; Thomas, S.; Wells, J.D.

    1996-07-01

    The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, G. For a supersymmetry breaking scale below a few 1,000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest standard model superpartner it decays by {chi}{sub 1}{sup 0} {r_arrow} {gamma} + G, and if kinematically accessible by {chi}{sub 1}{sup 0} {r_arrow} (Z{sup 0}, h{sup 0}, H{sup 0}, A{sup 0}) + G. These decays can give rise to displaced vertices. Alternately, if a slepton is the lightest standard model superpartner it decays by {tilde l} {r_arrow} l + G. This can be seen as a greater than minimum ionizing charged particle track, possibly with a kink to a minimum ionizing track.

  3. Low energy ion-molecule reactions

    SciTech Connect

    Farrar, J.M.

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  4. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  5. Low-energy irradiation effects in cellulose

    SciTech Connect

    Polvi, Jussi; Nordlund, Kai

    2014-01-14

    Using molecular dynamics simulations, we determined the threshold energy for creating defects as a function of the incident angle for all carbon and oxygen atoms in the cellulose monomer. Our analysis shows that the damage threshold energy is strongly dependent on the initial recoil direction and on average slightly higher for oxygen atoms than for carbon atoms in cellulose chain. We also performed cumulative bombardment simulations mimicking low-energy electron irradiation (such as TEM imaging) on cellulose. Analyzing the results, we found that formation of free molecules and broken glucose rings were the most common forms of damage, whereas cross-linking and chain scission were less common. Pre-existing damage was found to increase the probability of cross-linking.

  6. Low-energy neutral-atom spectrometer

    SciTech Connect

    Voss, D.E.; Cohen, S.A.

    1982-04-01

    The design, calibration, and performance of a low energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1 ..mu..sec time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu-Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200 ..mu..sec time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.

  7. RHIC low energy tests and initial operations

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; Mackay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-05-04

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by a search for the QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of {radical} s = 20.8 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with some of these challenges during beam tests with gold in March 2008, including first RHIC operations at {radical}s = 9.18 GeV/n and first beam experience at {radical}s = 5 GeV/n.

  8. Detection of low energy antimatter with emulsions

    NASA Astrophysics Data System (ADS)

    Aghion, S.; Ariga, A.; Ariga, T.; Bollani, M.; Dei Cas, E.; Ereditato, A.; Evans, C.; Ferragut, R.; Giammarchi, M.; Pistillo, C.; Romé, M.; Sala, S.; Scampoli, P.

    2016-06-01

    Emulsion detectors feature a very high position resolution and consequently represent an ideal device when particle detection is required at the micrometric scale. This is the case of quantum interferometry studies with antimatter, where micrometric fringes have to be measured. In this framework, we designed and realized a new emulsion based detector characterized by a gel enriched in terms of silver bromide crystal contents poured on a glass plate. We tested the sensitivity of such a detector to low energy positrons in the range 10–20 keV . The obtained results prove that nuclear emulsions are highly efficient at detecting positrons at these energies. This achievement paves the way to perform matter-wave interferometry with positrons using this technology.

  9. Low energy consumption spintronics using multiferroic heterostructures.

    PubMed

    Trassin, Morgan

    2016-01-27

    We review the recent progress in the field of multiferroic magnetoelectric heterostructures. The lack of single phase multiferroic candidates exhibiting simultaneously strong and coupled magnetic and ferroelectric orders led to an increased effort into the development of artificial multiferroic heterostructures in which these orders are combined by assembling different materials. The magnetoelectric coupling emerging from the created interface between the ferroelectric and ferromagnetic layers can result in electrically tunable magnetic transition temperature, magnetic anisotropy or magnetization reversal. The full potential of low energy consumption magnetic based devices for spintronics lies in our understanding of the magnetoelectric coupling at the scale of the ferroic domains. Although the thin film synthesis progresses resulted into the complete control of ferroic domain ordering using epitaxial strain, the local observation of magnetoelectric coupling remains challenging. The ability to imprint ferroelectric domains into ferromagnets and to manipulate those solely using electric fields suggests new technological advances for spintronics such as magnetoelectric memories or memristors.

  10. The Superconducting Super Collider Low Energy Booster

    SciTech Connect

    York, R.C.; Funk, W.; Garren, A.; Machida, S.; Mahale, N.K.; Peterson, J.; Pilat, F.; Wu, X. ); Wienands, U. )

    1991-05-01

    In collider fill mode, the Low Energy Booster (LEB) will accelerate 10{sup 12} protons in 114 bunches from an injection momentum of 1.22 GeV/c to a final momentum of 12 Gev/c, cycling at a frequency of 10 Hz. The most significant extension of present fast-cycling synchrotron technology arises from the requirement that the normalized transverse emittance (rms) of the beam be {le}0.6 {pi} {mu}m. In an alternative mode, the LEB will accelerate five times this current with a normalized transverse emittance {le} 4 {pi} {mu}m. A general overview of the design is presented. 7 refs., 2 figs., 4 tabs.

  11. Low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent {pi}{sup {plus_minus}}p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f{sup 2}=0.0756{plus_minus}0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P{sub 31} and P{sub 13} partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the {Sigma} term. Off-shell amplitudes are also provided. {copyright} {ital 1998} {ital The American Physical Society}

  12. Low-energy pion-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Ai, Li; Kaufmann, W. B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent π+/-p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756+/-0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided.

  13. Modification of polymer (PET) surface reactivity by low energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Bertrand, P.; De Puydt, Y.; Beuken, J.-M.; Lutgen, P.; Feyder, G.

    The surface of polyethylene terephtalate (PET) was studied by low energy He + ion scattering (ISS). Modifications of the surface composition induced by the He + and Ar + bombardments are observed. The ion bombardment causes surface damages with bond breaking and it results a highly activated surface for the chemisorption of nitrogen from the residual gas phase. Similar effects were observed on highly oriented pyrolytic graphite when analyzed in the same beam conditions.

  14. Revamping existing ammonia plants with a new low-energy process

    SciTech Connect

    Banquy, D.

    1984-01-01

    In this process, only part of the natural gas feed is treated in the primary reformer, and the rest is reformed directly in the secondary reformer using excess air. The excess nitrogen is removed in a cryogenic separation upstream of the synthesis loop. The features of this new low energy ammonia process, and the related advantages in terms of energy savings, make it suitable for revamping existing ammonia plants, with attractive economics.

  15. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  16. Low energy demonstration accelerator technical area 53

    SciTech Connect

    1996-04-01

    As part of the Department of Energy`s (DOE) need to maintain the capability of producing tritium in support of its historic and near-term stewardship of the nation`s nuclear weapons stockpile, the agency has recently completed a Programmatic Environmental Impact Statement for Tritium Supply and Recycling. The resulting Record of Decision (ROD) determined that over the next three years the DOE would follow a dual-track acquisition strategy that assures tritium production for the nuclear weapon stockpile in a rapid, cost effective, and safe manner. Under this strategy the DOE will further investigate and compare two options for producing tritium: (1) purchase of an existing commercial light-water reactor or irradiation services with an option to purchase the reactor for conversion to a defense facility; and (2) design, build, and test critical components of a system for accelerator production of tritium (APT). The final decision to select the primary production option will be made by the Secretary of Energy in the October 1998 time frame. The alternative not chosen as the primary production method, if feasible, would be developed as a back-up tritium supply source. This Environmental Assessment (EA) analyzes the potential environmental effects that would be expected to occur if the DOE were to design, build, and test critical prototypical components of the accelerator system for tritium production, specifically the front-end low-energy section of the accelerator, at Los Alamos National Laboratory. The Low Energy Demonstration Accelerator (LEDA) would be incrementally developed and tested in five separate stages over the next seven years. The following issues were evaluated for the proposed action: utility demands, air, human health, environmental restoration, waste management, transportation, water, threatened and endangered species, wetlands, cultural resources, and environmental justice.

  17. The Low Energy Effective Area of the Chandra Low Energy Transmission Grating Spectrograph

    NASA Technical Reports Server (NTRS)

    Pease, D.; Drake, J. J.; Johnson, C. O.; Kashya, V.; Ratzlaff, P. W.; Wargelin, B. J.; Brinkman, A. C.; Kaastra, J. S.; vanderMeer, R.; Paerels, F. B.

    2000-01-01

    The Chandra X-ray Observatory was successfully launched on July 23, 1999, and subsequently began an intensive calibration phase. We present the preliminary results from the in-flight calibration of the low energy response of the High Resolution Camera spectroscopic readout (HRC-S) combined with the Low Energy Transmission Grating (LETG) aboard Chandra. These instruments comprise the Low Energy Transmission Grating Spectrograph (LETGS). For this calibration study, we employ a pure hydrogen non-LTE white dwarf emission model (T = 25000 K and log g = 9.0) for comparison with the Chandra observations of Sirius B. The pre-flight calibration of the LETGS effective area only covered wavelengths shortward of 44 A (E less than 277 eV). Our Sirius B analysis shows that the HRC-S quantum efficiency (QE) model assumed for longer wavelengths leads to an overestimate of the effective area by an average factor of about 1.6. We derive a correction to the low energy HRC-S QE model to match the predicted and observed Sirius B spectra over the wavelength range of 44-185 A. We make an independent test of our results by the comparison of a Chandra LETGS observation of HZ 43 with pure hydrogen model atmosphere predictions and find good agreement.

  18. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  19. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  20. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  1. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  2. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  3. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  4. The effect of boron implant energy on transient enhanced diffusion in silicon

    SciTech Connect

    Liu, J.; Krishnamoorthy, V.; Gossman, H.; Rubin, L.; Law, M.E.; Jones, K.S.

    1997-02-01

    Transient enhanced diffusion (TED) of boron in silica after low energy boron implantation and annealing was investigated using boron-doping superlattices (DSLs) grown by low temperature molecular beam epitaxy. Boron ions were implanted at 5, 10, 20, and 40 keV at a constant dose of 2{times}10{sup 14}/cm{sup 2}. Subsequent annealing was performed at 750{degree}C for times of 3 min, 15 min, and 2 h in a nitrogen ambient. The broadening of the boron spikes was measured by secondary ion mass spectroscopy and simulated. Boron diffusivity enhancement was quantified as a function of implant energy. Transmission electron microscopy results show that {l_angle}311{r_angle} defects are only seen for implant energies {ge}10 keV at this dose and that the density increases with energy. DSL studies indicate the point defect concentration in the background decays much slower when {l_angle}311{r_angle} defects are present. These results imply there are at least two sources of TED for boron implants (B-I): short time component that decays rapidly consistent with nonvisible B-I pairs and a longer time component consistent with interstitial release from the {l_angle}311{r_angle} defects. {copyright} {ital 1997 American Institute of Physics.}

  5. Dental Implants

    MedlinePlus

    ... Procedures Dental Implants Dentures Direct Bonding Implants versus Bridges Orthodontics and Aligners Periodontal Plastic Surgery Porcelain Crowns Porcelain Fixed Bridges Porcelain Veneers Repairing Chipped Teeth Teeth Whitening Tooth- ...

  6. Electronic structure of nitinol surfaces oxidized by low-energy ion bombardment

    SciTech Connect

    Petravic, M. Varasanec, M.; Peter, R.; Kavre, I.; Metikos-Hukovic, M.; Yang, Y.-W.

    2014-06-28

    We have studied the electronic structure of nitinol exposed to low-energy oxygen-ion bombardment, using x-ray photoemission spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. XPS spectra reveal a gradual transformation of nitinol surfaces into TiO{sub 2} with increased dose of implanted oxygen. No oxidation of Ni atoms has been detected. NEXAFS spectra around O K-edge and Ti L{sub 2,3}-edge, reflecting the element-specific partial density of empty electronic states, exhibit features, which can be attributed to the creation of molecular orbitals, crystal field splitting, and the absence of long-range order, characteristic of the amorphous TiO{sub 2}. Based on these results, we discuss the oxidation kinetics of nitinol under low-energy oxygen-ion bombardment.

  7. Low-energy electron scattering from cyanamide

    NASA Astrophysics Data System (ADS)

    Wang, Kedong; Guo, Shuangcheng; Meng, Ju; Huang, Xiaotian; Wang, Yongfeng

    2016-09-01

    The low-energy electron collisions with cyanamide molecule are investigated by using the UK molecular R -matrix codes for electron energies ranging from 0.01 eV to 10 eV. Three models including static-exchange, static-exchange plus polarization, and close-coupling (CC) approximations are employed to reveal the dynamic interaction. Elastic (integrated and differential), momentum-transfer, and excitation cross sections from the ground state to the three low-lying electron excited states have been presented. Two shape resonances, two core-excited resonances, and two Feshbach resonances are detected in the CC approximation. The role of active space in the target and scattering problem including the resonances is discussed. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. These resonances may be responsible for the fragments observed in a recent experiment of the dissociative electron attachments to cyanamide. Since the cyanamide molecule has a large permanent dipole moment, a Born closure procedure is used to account for the contribution of partial waves higher than l =4 to obtain converged cross sections.

  8. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Brune, Carl R; Grimes, Steven M

    2006-03-30

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between 1 January 2003 and 31 December 2005 and supported by U.S. DOE grant number DE-FG03-03NA00074. Cross sections measured with high resolution have been subjected to an Ericson theory analysis to infer information about the nuclear level density. Other measurements were made of the spectral shape of particles produced in evaporation processes; these also yield level density information. A major project was the development of a new Hauser-Feshbach code for analyzing such spectra. Other measurements produced information on the spectra of gamma rays emitted in reactions on heavy nuclei and gave a means of refining our understanding of gamma-ray strength functions. Finally,reactions on light nuclei were studied and subjected to an R-matrix analysis. Cross sections fora network of nuclear reactions proceedingthrough a given compound nucleus shouldgreatly constrain the family of allowed parameters. Modifications to the formalism andcomputer code are also discussed.

  9. Low energy scattering with a nontrivial pion

    SciTech Connect

    Fariborz, Amir H.

    2007-12-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach.

  10. Low energy stable plasma calibration facility.

    PubMed

    Frederick-Frost, K M; Lynch, K A

    2007-07-01

    We have designed and fabricated a low energy plasma calibration facility for testing and calibration of rocket-borne charged-particle detectors and for the investigation of plasma sheath formation in an environment with ionospheric plasma energies, densities, and Debye lengths. We describe the vacuum system and associated plasma source, which was modified from a Naval Research Laboratory design [Bowles et al. Rev. Sci. Instrum. 67, 455 (1996)]. Mechanical and electrical modifications to this cylindrical microwave resonant source are outlined together with a different method of operating the magnetron that achieves a stable discharge. This facility produces unmagnetized plasmas with densities from 1x10(3)/cm(3) to 6x10(5)/cm(3), electron temperatures from 0.1 to 1.7 eV, and plasma potentials from 0.5 to 8 V depending on varying input microwave power and neutral gas flow. For the range of input microwave power explored (350-600 W), the energy density of the plasma remains constant because of an inverse relationship between density and temperature. This relationship allows a wide range of Debye lengths (0.3-8.4 cm) to be investigated, which is ideal for simulating the ionospheric plasma sheaths we explore.

  11. Low energy CMOS for space applications

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Alkalaj, Leon

    1992-01-01

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  12. Oscillations of very low energy atmospheric neutrinos

    SciTech Connect

    Peres, Orlando L. G.; Smirnov, A. Yu.

    2009-06-01

    There are several new features in the production, oscillations, and detection of the atmospheric neutrinos of low energies E < or approx. 100 MeV. The flavor ratio r of muon to electron neutrino fluxes is substantially smaller than 2 and decreases with energy, a significant part of events is due to the decay of invisible muons at rest, etc. Oscillations in a two-layer medium (atmosphere-Earth) should be taken into account. We derive analytical and semianalytical expressions for the oscillation probabilities of these 'sub-sub-GeV' neutrinos. The energy spectra of the e-like events in water Cherenkov detectors are computed, and the dependence of the spectra on the 2-3 mixing angle {theta}{sub 23}, the 1-3 mixing, and the CP-violation phase are studied. We find that variations of {theta}{sub 23} in the presently allowed region change the number of e-like events by about 15%-20% as well as lead to distortion of the energy spectrum. The 1-3 mixing and CP violation can lead to {approx}10% effects. Detailed study of the sub-sub-GeV neutrinos will be possible in future megaton-scale detectors.

  13. Low energy beam transport system developments

    NASA Astrophysics Data System (ADS)

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-01

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H- beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H- beams, but such gas densities cause unacceptably high H- beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H- beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  14. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. Cristina A.

    2012-06-01

    We report an investigation of processes that occur during the ignition of the plasma and its consequences in post-discharge time for an internal combustion engine, in order to find the appropriate parameters to be used in cars that operate with lean mixtures air-fuel. The relevance of this theme has attracted much attention, and has been one of the subjects of collaboration between experimental and theoretical groups in the USA and Brazil. We have produced some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules were obtained, using the linear transmission method based on the Beer-Lambert law to first approximation. Measurements and calculations of differential cross sections for low-energy (rotationally unresolved) electron scattering were also obtained, for scattering angles of 5 --130 . The measurements were taken using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Additionally to these, computer simulation studies of electronic discharge in mixtures of ethanol were performed, using a Zero-Dimensional Plasma Kinetic solver. Previous reported models for combustion of ethanol and cross sections data for momentum transfer of electron collisions with ethanol were used. The time evolutions of the main species densities are reported and the ignition time delay discussed.

  15. Low-energy electron-atom bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1986-01-01

    This paper extends recent work providing an elementary calculation of bremsstrahlung and opacity associated with the scattering of low-energy electrons by neutral atoms and molecules. The method applies when the scattering potential is 'hard' or when the collision time is short, applying the classical soft-photon emission probability formula for arbitrary bremsstrahlung photon energy. However, now, in addition to correcting the probability factor for finite bremsstrahlung photon energy, another factor corrects for the reduced phase space available to the outgoing electron. The bremsstrahlung cross section and opacity are then computed directly from the elastic scattering cross section, determined experimentally or calculated; a small (approximately 10 percent) correction is computed from the anisotropic term in the elastic scattering cross section. The opacity is evaluated for electron scattering by H, He, and H2 using experimentally determined values for the elastic scattering cross section, and is compared with more elaborate calculations. The agreement is good (within 10 percent), indicating an accuracy for the general method comparable to variations among the results of different elaborate theoretical computations. The agreement seems to validate the basic approximation of short collision time even at large bremsstrahlung photon energy for electron energies and temperatures up to a few eV.

  16. Optimal Low Energy Earth-Moon Transfers

    NASA Technical Reports Server (NTRS)

    Griesemer, Paul Ricord; Ocampo, Cesar; Cooley, D. S.

    2010-01-01

    The optimality of a low-energy Earth-Moon transfer is examined for the first time using primer vector theory. An optimal control problem is formed with the following free variables: the location, time, and magnitude of the transfer insertion burn, and the transfer time. A constraint is placed on the initial state of the spacecraft to bind it to a given initial orbit around a first body, and on the final state of the spacecraft to limit its Keplerian energy with respect to a second body. Optimal transfers in the system are shown to meet certain conditions placed on the primer vector and its time derivative. A two point boundary value problem containing these necessary conditions is created for use in targeting optimal transfers. The two point boundary value problem is then applied to the ballistic lunar capture problem, and an optimal trajectory is shown. Additionally, the ballistic lunar capture trajectory is examined to determine whether one or more additional impulses may improve on the cost of the transfer.

  17. RHIC low-energy challenges and plans

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; MacKay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Schoefer, V.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-06-08

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by the search for a possible QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy {radical}s = 19.6 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with these challenges during beam tests with gold beams in March 2008. This includes first operations at {radical}s = 9.18 GeV/n, first beam experience at {radical}s = 5 GeV/n, and luminosity projections for near-term operations.

  18. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    2001-11-01

    New space missions are increasingly more complex; demand for exotic orbits to solve engineering problems has grown beyond the existing astrodynamic infrastructure based on two-body interactions. The delicate heteroclinic dynamics used by the Genesis Mission dramatically illustrate the need for a new paradigm: dynamical system study of three-body problem. Furthermore, this dynamics has much to say about the morphology and transport of materials within the Solar System. The cross-fertilization of ideas between the natural dynamics of the Solar System and applications to engineering has produced new techniques for constructing spacecraft trajectories with interesting characteristics. Specifically, these techniques are used here to produce a lunar capture mission which uses less fuel than a Hohmann transfer. We approximate the Sun-Earth-Moon-Spacecraft four-body problem as two three-body problems. Using the invariant manifold structures of the Lagrange points of the three-body systems, we are able to construct low energy transfer trajectories from the Earth which exhibit ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations. This is joint work with Martin W. Lo, Jerrold E. Marsden and Shane D. Ross and was partially supported by the National Science Foundation Grant No. KFI/ATM-9873133 under a contract with the Jet Propulsion Laboratory, NASA.

  19. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. C. A.; Silva, D. G. M.; Bettega, M. H. F.; da Costa, R. F.; Lima, M. A. P.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2012-11-01

    In order to understand and optimize processes occurring during the ignition of plasma and its consequences in post-discharge for an internal combustion engine, especially considering the spark plug, we have produced in this work some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules in the energy range from 60 to 500 eV are reported, using the linear transmission method based on the Beer-Lambert law to first approximation. Aditionally to that, measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering were also discussed, for impact energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. The measurements were obtained using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons.

  20. New Cooperative Mechanisms of Low-Energy Nuclear Reactions Using Super Low-Energy External Field

    NASA Astrophysics Data System (ADS)

    Gareev, F. A.; Zhidkova, I. E.

    We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system.

  1. Absolute calorimetric calibration of low energy brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Stump, Kurt E.

    In the past decade there has been a dramatic increase in the use of permanent radioactive source implants in the treatment of prostate cancer. A small radioactive source encapsulated in a titanium shell is used in this type of treatment. The radioisotopes used are generally 125I or 103Pd. Both of these isotopes have relatively short half-lives, 59.4 days and 16.99 days, respectively, and have low-energy emissions and a low dose rate. These factors make these sources well suited for this application, but the calibration of these sources poses significant metrological challenges. The current standard calibration technique involves the measurement of ionization in air to determine the source air-kerma strength. While this has proved to be an improvement over previous techniques, the method has been shown to be metrologically impure and may not be the ideal means of calbrating these sources. Calorimetric methods have long been viewed to be the most fundamental means of determining source strength for a radiation source. This is because calorimetry provides a direct measurement of source energy. However, due to the low energy and low power of the sources described above, current calorimetric methods are inadequate. This thesis presents work oriented toward developing novel methods to provide direct and absolute measurements of source power for low-energy low dose rate brachytherapy sources. The method is the first use of an actively temperature-controlled radiation absorber using the electrical substitution method to determine total contained source power of these sources. The instrument described operates at cryogenic temperatures. The method employed provides a direct measurement of source power. The work presented here is focused upon building a metrological foundation upon which to establish power-based calibrations of clinical-strength sources. To that end instrument performance has been assessed for these source strengths. The intent is to establish the limits of

  2. Low energy beam transport system developments

    SciTech Connect

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-08

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H{sup −} beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H{sup −} beams, but such gas densities cause unacceptably high H{sup −} beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H{sup −} beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  3. Transferring Gus gene into intact rice cells by low energy ion beam

    NASA Astrophysics Data System (ADS)

    Zengliang, Yu; Jianbo, Yang; Yuejin, Wu; Beijiu, Cheng; Jianjun, He; Yuping, Huo

    1993-06-01

    A new technique of transferring genes by low energy ion beam has been reported in this paper. The Gus and CAT (chloramphenicol acetyltransferase) genes, as "foreign" genetic materials, were introduced into the suspension cells and ripe embryos or rice by implantation of 20-30 keV Ar + at doses ranging from 1 × 10 15 to 4 × 10 15 ions/cm 2. The activities of CAT and Gus were detected in the cells and embryos after several weeks. The results indicate that the transfer was a success.

  4. AstroBox2 - Detector for low-energy β-delayed particle detection

    NASA Astrophysics Data System (ADS)

    Saastamoinen, A.; Pollacco, E.; Roeder, B. T.; Spiridon, A.; Daq, M.; Trache, L.; Pascovici, G.; De Oliveira, R.; Rodrigues, M. R. D.; Tribble, R. E.

    2016-06-01

    Efficient suppression of β-background is essential for studies of low-energy β-delayed charged particle decays of astrophysical interest. A promising method for such studies has been a micro pattern gas amplifier detector where the sample is implanted into the gas volume and the decays that follow are observed with high gain and signal to noise ratio. An upgraded version of the original AstroBox detector has been built and commissioned at Texas A&M University. Here a description of the new AstroBox2 detector is given, selected results from the commissioning tests are presented, and future perspectives discussed.

  5. Influence of the residual oxygen in the plasma immersion ion implantation (PI3) processing of materials

    NASA Astrophysics Data System (ADS)

    Ueda, M.; Silva, A. R.; Mello, Carina B.; Silva, G.; Reuther, H.; Oliveira, V. S.

    2011-12-01

    In this work, we investigated the effects of the contaminants present in the vacuum chamber of the PI3 system, in particular, the residual oxygen, which results in the formation of the oxide compounds on the surface and hence is responsible for the high implantation energies required to achieve reasonably thick treated layers. We used a mass spectrometer (RGA) with a quadruple filter to verify the composition of the residual vacuum and pressure of the elements present in the chamber. Initially we found a high proportion of residual oxygen in a vacuum with a pressure of 1 × 10 -3 Pa. Minimizing the residual oxygen percentage in about 80%, by efficient cleaning of the chamber walls and by improving the gas feeding process, we mitigated the formation of oxides during the PI3 process. Therefore we achieved a highly efficient PI3 processing obtaining implanted layers reaching about 50 nm, even in cases such as an aluminum alloy, where is very difficult to nitrogen implant at low energies. We performed nitrogen PI3 treatment of SS304 and Al7075 using pulses of only 3 kV and 15 × 10 -6 s at 1 kHz with an operating pressure of 1 Pa.

  6. Development of a Low-energy Trigger for VERITAS

    SciTech Connect

    Kildea, J.

    2008-12-24

    During the 2007/2008 observing season a low-energy trigger configuration was developed and tested for VERITAS. The configuration makes uses of the small ({approx}35 m) baseline between two of the VERITAS telescopes and employs a much lower discriminator threshold and tighter coincidence window compared to the standard VERITAS trigger. Five hours of Crab Nebula ON/OFF observations were obtained in low-energy mode and were used to test new low-energy analysis algorithms. We present some details of the VERITAS low-energy trigger and the associated data analysis.

  7. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  8. Enhancement of the Gibberella zeae growth inhibitory lipopeptides from a Bacillus subtilis mutant by ion beam implantation.

    PubMed

    Liu, J; Liu, M; Wang, J; Yao, J M; Pan, R R; Yu, Z L

    2005-11-01

    Bacillus subtilis JA antagonized the growth of Gibberella zeae. In order to reduce growth of this fungi pathogen to a greater extent, low-energy ion beam implantation was applied in mutant breeding. We studied the effects of different energies and different doses of nitrogen ion implantation. The mutant strain designated as JA026 was obtained showing higher inhibition activity in the screening plate. Its inhibition zone against indicator organism increased by 14.3% compared to the original strain. The electrospray ionization mass spectrometry (ESI/MS) analysis indicated that the antifungal lipopeptides produced by the mutant were identical to those produced by the wild-type strain. The mutant strain exhibited favorable properties including the high yield of antifungal lipopeptides production and faster growth over the parent strain, which suggested that this strain would be a promising biocontrol candidate in agriculture.

  9. Low-energy electron collisions with thiophene

    NASA Astrophysics Data System (ADS)

    da Costa, R. F.; Varella, M. T. do N.; Lima, M. A. P.; Bettega, M. H. F.

    2013-05-01

    We report on elastic integral, momentum transfer, and differential cross sections for collisions of low-energy electrons with thiophene molecules. The scattering calculations presented here used the Schwinger multichannel method and were carried out in the static-exchange and static-exchange plus polarization approximations for energies ranging from 0.5 eV to 6 eV. We found shape resonances related to the formation of two long-lived π* anion states. These resonant structures are centered at the energies of 1.00 eV (2.85 eV) and 2.82 eV (5.00 eV) in the static-exchange plus polarization (static-exchange) approximation and belong to the B1 and A2 symmetries of the C2v point group, respectively. Our results also suggest the existence of a σ* shape resonance in the B2 symmetry with a strong d-wave character, located at around 2.78 eV (5.50 eV) as obtained in the static-exchange plus polarization (static-exchange) calculation. It is worth to mention that the results obtained at the static-exchange plus polarization level of approximation for the two π* resonances are in good agreement with the electron transmission spectroscopy results of 1.15 eV and 2.63 eV measured by Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004), 10.1021/jp048759a]. The existence of the σ* shape resonance is in agreement with the observations of Dezarnaud-Dandiney et al. [J. Phys. B 31, L497 (1998), 10.1088/0953-4075/31/11/004] based on the electron transmission spectra of dimethyl(poly)sulphides. A comparison among the resonances of thiophene with those of pyrrole and furan is also performed and, altogether, the resonance spectra obtained for these molecules point out that electron attachment to π* molecular orbitals is a general feature displayed by these five-membered heterocyclic compounds.

  10. Characteristics of low energy atom and molecule beams generated by the charge exchange reaction

    SciTech Connect

    Hara, Yasuhiro; Takashima, Seigo; Toyoda, Hirotaka; Sekine, Makoto; Hori, Masaru; Yamakawa, Koji; Den, Shoji

    2008-03-01

    A low energy NB source, which consisted of a surface wave plasma (SWP) source and two large diameter carbon electrodes, was developed for damageless etching of ultralarge-scale integrated devices. Ion beams were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber, and then neutralized without energy loss by a charge exchange reaction. The energy distribution functions of an Ar ion beam and an Ar atom beam was observed using a quadrupole mass spectroscope equipped with an energy analyzer. The energy of the Ar ion beam and the Ar atom beam was controlled by the acceleration voltage. N{sub 2} ion and N ion beams were also extracted from a nitrogen plasma source. The intensity ratio of the N ion beam to the N{sub 2} ion beam was 5:9, indicating that N ions were efficiently generated in the nitrogen SWP. The N{sub 2} ion and N ion beams were changed to N{sub 2} molecule and N atom beams, respectively, through a charge exchange reaction without energy loss. The energy of these beams was controlled by the acceleration voltage and was in the region less of than 100 eV. When the acceleration voltage is higher than 40 V, not only the primary peaks due to the N{sub 2} ion beam or N ion beam were observed but also a low energy second peak was observed in the energy distribution. The energy of the low energy second peak was controlled by the acceleration voltage. It was concluded that the low energy second peak corresponds to the N{sub 2} molecule ion beam and the N ion beam, which is extracted from the second plasma generated in the space between the two carbon electrodes.

  11. Using a CCD for the direct detection of electrons in a low energy space plasma spectrometer

    NASA Astrophysics Data System (ADS)

    Bedington, R.; Kataria, D.; Walton, D.

    2012-01-01

    An E2V CCD64 back-illuminated, ion-implanted CCD (charge-coupled device) has been used as a direct electron imaging detector with CATS (Conceptual And Tiny Spectrometer), a highly miniaturised prototype plasma analyser head. This is in place of an MCP (microchannel plate) with a position sensing anode which would more conventionally be used as a detector in traditional low energy space plasma analyser instruments. The small size of CATS however makes it well matched to the size of the CCD, and the ion implants reduce the depth of the CCD backside electron potential well making it more sensitive to lower energy electrons than standard untreated silicon. Despite ionisation damage from prolonged exposure to excessively energetic electrons, the CCD has been able to detect electrons with energies above 500eV, at temperatures around room temperature. Using both a long integration 'current measuring' mode and a short integration `electron counting' mode it has been used to image the low energy electrons exiting the analyser, enhancing our understanding of the CATS electrostatic optics. The CCD has been selected as the detector for use with CATS for an instrument on a low-altitude student sounding rocket flight. Although it cannot detect the lowest energy electrons that an MCP can detect, and it is more sensitive to stray light, the low voltages required, the lack of vacuum requirements and its novelty and availability made it the most attractive candidate detector.

  12. What is a low-energy house and who cares?

    SciTech Connect

    Litt, B.R.

    1994-12-01

    Most energy analysts view low-energy houses as good things, yet differ in their expectations of what exactly a low energy house is. There are two intertwining threads to this report. The first is an evaluation of 50 buildings that have been claimed to be low-energy residences, for which monitored energy performance data have been collected. These data represent the preliminary effort in the ongoing update of the Buildings Energy-Use Compilation and Analysis (BECA) data base for new residences. The second thread concerns the definition of a low-energy house. After the elements of a definition are presented, their implications for actors involved in providing housing are identified. Several more tractable definitions are applied to the houses in this compilation. The outcomes illustrate ways in which different interests are served by various definitions. Different definitions can yield very different energy rankings. No single definition of a low-energy house is universally applicable.

  13. A comparative study on low-energy ion beam and neutralized beam modifications of naked DNA and biological effect on mutation

    NASA Astrophysics Data System (ADS)

    Sarapirom, S.; Thongkumkoon, P.; Prakrajang, K.; Anuntalabhochai, S.; Yu, L. D.

    2012-02-01

    DNA conformation change or damage induced by low-energy ion irradiation has been of great interest owing to research developments in ion beam biotechnology and ion beam application in biomedicine. Mechanisms involved in the induction of DNA damage may account for effect from implanting ion charge. In order to check this effect, we used both ion beam and neutralized beam at keV energy to bombard naked DNA. Argon or nitrogen ion beam was generated and extracted from a radiofrequency (RF) ion source and neutralized by microwave-driven plasma in the beam path. Plasmid DNA pGFP samples were irradiated with the ion or neutralized beam in vacuum, followed by gel electrophoresis to observe changes in the DNA conformations. It was revealed that the ion charge played a certain role in inducing DNA conformation change. The subsequent DNA transfer into bacteria Escherichia coli ( E. coli) for mutation analysis indicated that the charged ion beam induced DNA change had high potential in mutation induction while neutralized beam did not. The intrinsic reason was attributed to additional DNA deformation and contortion caused by ion charge exchange effect so that the ion beam induced DNA damage could hardly be completely repaired, whereas the neutralized beam induced DNA change could be more easily recoverable owing to absence of the additional DNA deformation and contortion.

  14. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  15. Dental Implants.

    PubMed

    Zohrabian, Vahe M; Sonick, Michael; Hwang, Debby; Abrahams, James J

    2015-10-01

    Dental implants restore function to near normal in partially or completely edentulous patients. A root-form implant is the most frequently used type of dental implant today. The basis for dental implants is osseointegration, in which osteoblasts grow and directly integrate with the surface of titanium posts surgically embedded into the jaw. Radiologic assessment is critical in the preoperative evaluation of the dental implant patient, as the exact height, width, and contour of the alveolar ridge must be determined. Moreover, the precise locations of the maxillary sinuses and mandibular canals, as well as their relationships to the site of implant surgery must be ascertained. As such, radiologists must be familiar with implant design and surgical placement, as well as augmentation procedures utilized in those patients with insufficient bone in the maxilla and mandible to support dental implants.

  16. Parity violation in low-energy neutron-deuteron scattering

    SciTech Connect

    Song, Young-Ho; Gudkov, Vladimir; Lazauskas, Rimantas

    2011-01-15

    Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques, Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Born approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The resulting relation between physical observables and low-energy constants can be used to fix low-energy constants from experiments. Potential model dependencies of parity-violating effects are discussed.

  17. [Hearing implants].

    PubMed

    Stokroos, Robert J; George, Erwin L J

    2013-01-01

    In the Netherlands, more than 1.5 million people suffer from sensorineural hearing loss or deafness. However, fitting conventional hearing aids does not provide a solution for everyone. In recent decades, developments in medical technology have produced implantable and other devices that restore both sensorineural and conductive hearing losses. These hearing devices can be categorized into bone conductive devices, implantable middle ear prostheses, cochlear implants and auditory brainstem implants. Furthermore, new implants aimed at treating tinnitus and loss of vestibular function have recently been developed.

  18. Past, present and future low energy antiproton facilities at CERN

    NASA Astrophysics Data System (ADS)

    Bartmann, W.; Belochitskii, P.; Breuker, H.; Butin, F.; Carli, C.; Eriksson, T.; Maury, S.; Oelert, W.; Pasinelli, S.; Tranquille, G.

    2014-05-01

    Low energy antiprotons are available for physics experiments at CERN since the 1980s and have been used by a large variety of experiments. The Low Energy Antiproton Ring LEAR has been constructed as a complementary use of antiprotons available at that time for high energy physics and delivered beam to experiments mainly using slow extraction. After completion of LEAR exploitation, the Antiproton Decelerator (AD) was constructed (adaptation of the existing Antiproton Collector, AC) to allow for a simpler low energy antiproton scheme (only one accelerator operated with Antiprotons) with fast extraction well suited for trap experiments. The Extra Low ENergy Antiproton ring ELENA is a small synchrotron presently constructed to further decelerate antiprotons from the AD in a controlled manner, and to reduce emittances with the help of an electron cooler to improve the capture efficiencies of existing experiments and allow for additional ones.

  19. Radial Flux Distribution of Low-Energy Neutrons.

    ERIC Educational Resources Information Center

    Higinbotham, J.

    1979-01-01

    Describes an experiment designed to illustrate the basic principle involved in the process of moderation of fast neutrons by water, and the monitoring of the low-energy neutron flux using indium as a probe. (GA)

  20. Biological assessments for the low energy demonstration accelerator, 1996

    SciTech Connect

    Cross, S.

    1997-03-01

    This report discusses the biological impact to the area around the Los Alamos National Laboratory of the Low Energy Demonstration Accelerator. In particular the impact to the soils, water quality, vegetation, and wildlife are discussed.

  1. Beam lifetime and limitations during low-energy RHIC operation

    SciTech Connect

    Fedotov, A.V.; Bai, M.; Blaskiewicz, M.; Fischer, W.; Kayran, D.; Montag, C.; Satogata, T.; Tepikian, S.; Wang, G.

    2011-03-28

    The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

  2. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.

  3. Etching and Damage Action on Microbes' Cells by Low Energy N+ Beam

    NASA Astrophysics Data System (ADS)

    Song, Dao-jun; Yu, Zeng-liang

    2000-08-01

    The action of etching and damage by 20 keV N+ beam on the cells of Deinococcus radiodurans and Escherichia coli was investigated by scanning electron microscope (SEM) and the electron spin resonance (ESR) spectrum of free radicals. The results showed that N+ implantation exerted the direct action of etching and damage of momentum transferring and the indirect action of the free radicals of energy deposition on their cells, many microholes were found on the surface of cells' wall and/or membrane by SEM, the damaged DNA was determined using DNA unwinding technique, and the signal of free radicals was measured by ESR. The degree of damage to cells by ion beam gradually increased with the increase implantation dose. With the post-treatment of 2 mmol/l caffeine and 0.5 mmol/l Na2-EDTA, the survival rate of D.radiodurans and E.coli further decreased in the order of caffeine > Na2-EDTA > control, and this suggested that low energy ion beam could be implanted into nucleus, doing a damage to DNA and resulting in the mutation of organisms.

  4. Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy.

    PubMed

    Maleki-Ghaleh, H; Khalil-Allafi, J; Sadeghpour-Motlagh, M; Shakeri, M S; Masoudfar, S; Farrokhi, A; Beygi Khosrowshahi, Y; Nadernezhad, A; Siadati, M H; Javidi, M; Shakiba, M; Aghaie, E

    2014-12-01

    The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release. PMID:25064465

  5. Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy.

    PubMed

    Maleki-Ghaleh, H; Khalil-Allafi, J; Sadeghpour-Motlagh, M; Shakeri, M S; Masoudfar, S; Farrokhi, A; Beygi Khosrowshahi, Y; Nadernezhad, A; Siadati, M H; Javidi, M; Shakiba, M; Aghaie, E

    2014-12-01

    The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.

  6. Effect of Implantation Sequence on Tribological Behavior of GCr15 Steel by PBII

    NASA Astrophysics Data System (ADS)

    Gu, Le; Zhou, Hui; Cao, Guojian; Tang, Guangze; Ma, Xinxin; Wang, Liqin

    2016-05-01

    In the present work, the effect of implantation sequence on tribological behavior of GCr15 steel treated by plasma-based ion implantation of carbon and nitrogen has been investigated. The treated GCr15 steels were characterized for microstructure and abrasive wear performance through combination of Raman spectroscopy, nano-indentation, and wear tests. Raman spectroscopy indicated that diamond-like carbon (DLC) films were formed after implantation of carbon with or without implantation of nitrogen, and the implantation of nitrogen after the implantation of carbon destroyed the graphite structure of the DLC films. The nano-indentation and wear tests showed that nanohardness as well as wear resistance of the GCr15 steel treated with the implantation sequence of nitrogen-carbon was better than those with the implantation sequence of carbon-nitrogen. Meanwhile, the properties were improved with increasing of carbon ion fluence.

  7. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.

  8. Design of low energy bunch compressors with space charge effects

    NASA Astrophysics Data System (ADS)

    He, A.; Willeke, F.; Yu, L. H.; Yang, L.; Shaftan, T.; Wang, G.; Li, Y.; Hidaka, Y.; Qiang, J.

    2015-01-01

    In this paper, we explore a method to manipulate low energy electron bunches in a space charge dominated regime, and we use this method to design low energy linac bunch compressors to compress electron bunches in a space charge dominated regime. In the method, we use the space charge effects instead of avoiding them; i.e., we use the space charge forces to generate the required energy chirp instead of the ordinary method which uses the rf accelerating system to generate the chirp. We redefine the concepts of the dispersion function and beta functions in a space charge dominated regime to guide the optimization. Using this method, we study the low energy (5-22 MeV) linac bunch compressor design to produce short (˜150 fs ) and small size (˜30 μ m ) bunches for the electron beam slicing project. The low energy linac bunch compressors work in a space charge dominated regime, and the bunches at the downstream of the gun have a negative energy chirp due to the space charge effects. To provide compression for the negative energy chirped bunch, we design a positive R56 dispersive section using a four-dipole chicane with several quadrupole magnets. We have designed low energy linac bunch compressors with different photocathode rf guns. For example, one linac bunch compressor with the BNL photocathode electron rf gun has achieved a low energy bunch with the 166 fs rms bunch length, 28 and 31 μ m rms beam size in the vertical and horizontal directions, respectively, at 5 MeV with 50 pC charge. Another example with LBNL's very-high frequency gun has achieved a low energy bunch with the 128 fs rms bunch length, 42 and 25 μ m rms beam size in the vertical and horizontal directions, respectively, at 22 MeV with 200 pC charge.

  9. Low energy availability in the marathon and other endurance sports.

    PubMed

    Loucks, Anne B

    2007-01-01

    Energy availability is the amount of dietary energy remaining after exercise training for all other metabolic processes. Excessively low energy availability impairs reproductive and skeletal health, although genetics and age may alter an individual's initial conditions and sensitivity when low energy availability is imposed. Many marathon runners and other endurance athletes reduce energy availability either (i) intentionally to modify body size and composition for improving performance; (ii) compulsively in a psychopathological pattern of disordered eating; or (iii) inadvertently because there is no strong biological drive to match energy intake to activity-induced energy expenditure. Inadvertent low energy availability is more extreme when consuming a low fat, high carbohydrate diet. Low energy availability, reproductive disorders, low bone mineral density and stress fractures are more common in female than male athletes. Functional menstrual disorders caused by low energy availability should be diagnosed by excluding diseases that also disrupt menstrual cycles. To determine energy availability (in units of kilocalories or kilojoules per kilogram of fat-free mass), athletes can record their diets and use diet analysis software to calculate energy intake, measure energy expenditure during exercise using a heart monitor and measure fat-free mass using a bioelectrical impedance body composition scale. All are commercially available at consumer prices.

  10. Rate of F center formation in sapphire under low-energy low-fluence Ar+ irradiation

    NASA Astrophysics Data System (ADS)

    Epie, E. N.; Wijesundera, D. N.; Tilakaratne, B. P.; Chen, Q. Y.; Chu, W. K.

    2016-03-01

    Ionoluminescence, optical absorption spectroscopy and Rutherford backscattering spectrometry channelling (RBS-C) have been used to study the rate of F center formation with fluence in 170 keV Ar+ irradiated single crystals of α-Al2O3 (sapphire) at room temperature. Implantation fluences range between 1013 cm-2 and 5 ×1014 cm-2. F center density (NF) has been found to display an initial rapid linear increase with Ar+ fluence followed by saturation to a maximum value of 1.74 ×1015 cm-2. Experimental results show a 1-1 correlation between radiation damage in the oxygen sublattice and F center density. This suggest F center kinetics in sapphire under low-energy low-fluence Ar irradiation is a direct consequence of dynamic competition between oxygen defect creation and recombination. An attempt has also been made to extend this discussion to F center kinetics in sapphire under swift heavy ion irradiation.

  11. Low energy x-ray response of Ge detectors with amorphous Ge entrance contacts

    SciTech Connect

    Luke, P.N.; Rossington, C.S.; Wesela, M.F.

    1993-10-01

    The low energy x-ray response of GI detectors with amorphous GI entrance contacts has been evaluated. The spectral background due to near contact incomplete charge collection was found to consist of two components: a low level component which is insensitive to applied voltage and a high level step-like component which is voltage dependent. At high operating voltages, the high level component can be completely suppressed, resulting in background levels which are much lower than those previously observed using GI detectors with Pd surface barrier or B ion implanted contacts, and which also compare favorably to those obtained with Si(Li) x-ray detectors. The response of these detectors to {sup 55}Fe and 1.77 keV x-rays is shown. A qualitative explanation of the origins of the observed background components is presented.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  13. EVOLUTION OF THE CRAB NEBULA IN A LOW ENERGY SUPERNOVA

    SciTech Connect

    Yang, Haifeng; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-06-20

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼10{sup 50} erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  14. Coulomb effects in low-energy nuclear fragmentation

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

    1993-01-01

    Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

  15. Feasibility of Electron Cooling for Low-Energy RHIC Operation

    SciTech Connect

    Fedotov,A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.; Pozdeyev, E.; Satogata, T.

    2008-04-01

    A concrete interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has recently emerged. Providing collisions in this energy range, which in the RHIC case is termed 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of a critical point on the QCD phase diagram. However, luminosity projections are relatively low for the lowest energy points of interest. Luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes the expected luminosity improvement with electron cooling, possible technical approaches and various limitations.

  16. The problem of low energy particle measurements in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1978-01-01

    The accurate measurement of low energy (less than 100 eV) particle properties in the magnetosphere has been difficult, partly because of the low density of such particles, but more particularly because of spacecraft interference effects. Some early examples of how these phenomena have affected particle measurements on an OGO spacecraft are presented. Data obtained with the UCSD particle detectors on ATS-6 are then presented showing how some of these difficulties have been partially overcome. Future measurements of low energy particles in the magnetosphere can be improved by: (1) improving the low energy resolution of detectors; (2) building electrostatically clean spacecraft; (3) controlling spacecraft potential; and (4) using auxiliary measurements, particularly wave data.

  17. Evolution of the Crab Nebula in a Low Energy Supernova

    NASA Astrophysics Data System (ADS)

    Yang, Haifeng; Chevalier, Roger A.

    2015-06-01

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼1050 erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  18. Correlation among low-energy four-nucleon observables

    NASA Astrophysics Data System (ADS)

    Adhikari, Sadhan K.

    1981-07-01

    We study the correlation among s-wave low-energy four-nucleon observables by using a simplified dispersion theoretic (ND) approach. We find that the triton binding energy, its asymptotic normalization parameter, the deuteron exchange left-hand cut, and the nucleon-trinucleon (N-t) scattering length control the low-energy N-t system. The isospin one channel is insensitive to the asymptotic normalization parameter of the triton. The effective range function k δ for the isospin zero spin singlet N-t system has a pole whose position and residue are strongly correlated with the N-t scattering length. In this case the four-nucleon system (in our model) has an excited state whose binding energy and asymptotic normalization parameter are also correlated with the N-t scattering length. [NUCLEAR REACTIONS s-wave nucleon-trinucleon systems, spin-isospin channels, ND approach, low-energy correlations.

  19. IONS (ANURADHA): Ionization states of low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Biswas, S.; Chakraborti, R.; Cowsik, R.; Durgaprasad, N.; Kajarekar, P. J.; Singh, R. K.; Vahia, M. N.; Yadav, J. S.; Dutt, N.; Goswami, J. N.

    1987-01-01

    IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays.

  20. Light element production by low energy nuclei from massive stars

    NASA Technical Reports Server (NTRS)

    Vangioni-Flam, E.; Casse, M.; Ramaty, R.

    1997-01-01

    The Orion complex is a source of gamma rays attributed to the de-excitation of fast carbon and oxygen nuclei excited through interactions with ambient hydrogen and helium. This has consequences for the production and evolution of light isotopes in the Galaxy, as massive stars appear as prolific sources of C-O rich low energy nuclei. The different stages of massive star evolution are considered in relation to the acceleration of nuclei to moderate energies. It is concluded that the low energy nuclear component originating from massive stars plays a larger role than the usual Galactic cosmic rays in shaping the evolution of Li-6, Be-9, B-10 and B-11, especially in the early Galactic evolution. The enhancement of the B-11/B-10 ratio observed in meteorites and in the interstellar medium is attributed to the interaction of low energy carbon nuclei with ambient H and to a lesser degree, to neutrino spallation.

  1. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J. . Physics Dept.); Kivelson, S.A. . Dept. of Physics)

    1992-01-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the universality'' of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  2. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J.; Kivelson, S.A.

    1992-09-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the ``universality`` of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  3. Histrelin Implant

    MedlinePlus

    ... response to histrelin implant. Your blood sugar and glycosylated hemoglobin (HbA1c) should be checked regularly.Ask your pharmacist any questions you have about histrelin implant.It is important for you to keep a written list of all of the prescription and ...

  4. Local formation of nitrogen-vacancy centers in diamond by swift heavy ions

    SciTech Connect

    Schwartz, J.; Aloni, S.; Ogletree, D. F.; Tomut, M.; Bender, M.; Severin, D.; Trautmann, C.; Rangelow, I. W.; Schenkel, T.

    2014-12-07

    We exposed nitrogen-implanted diamonds to beams of swift heavy ions (∼1 GeV, ∼4 MeV/u) and find that these irradiations lead directly to the formation of nitrogen vacancy (NV) centers, without thermal annealing. We compare the photoluminescence intensities of swift heavy ion activated NV{sup −} centers to those formed by irradiation with low-energy electrons and by thermal annealing. NV{sup −} yields from irradiations with swift heavy ions are 0.1 of yields from low energy electrons and 0.02 of yields from thermal annealing. We discuss possible mechanisms of NV center formation by swift heavy ions such as electronic excitations and thermal spikes. While forming NV centers with low efficiency, swift heavy ions could enable the formation of three dimensional NV{sup −} assemblies over relatively large distances of tens of micrometers. Further, our results show that NV center formation is a local probe of (partial) lattice damage relaxation induced by electronic excitations from swift heavy ions in diamond.

  5. Techniques and methods for the low-energy neutrino detection

    NASA Astrophysics Data System (ADS)

    Ranucci, Gioacchino

    2016-04-01

    Low-energy neutrino physics and astrophysics has been one of the most active field of particle physics research over the past two decades, achieving important and sometimes unexpected results, which have paved the way for a bright future of further exciting studies. The methods, the techniques and the technologies employed for the construction of the many experiments which acted as important players in this area of investigation have been crucial elements to reach the many accumulated physics successes. The topic covered in this review is, thus, the description of the main features of the set of methodologies at the basis of the design, construction and operation of low-energy neutrino detectors.

  6. Scattering of low-energy neutrinos on atomic shells

    SciTech Connect

    Babič, Andrej; Šimkovic, Fedor

    2015-10-28

    We present a derivation of the total cross section for inelastic scattering of low-energy solar neutrinos and reactor antineutrinos on bound electrons, resulting in a transition of the electron to an excited state. The atomic-shell structure of various chemical elements is treated in terms of a nonrelativistic approximation. We estimate the interaction rates for modern neutrino detectors, in particular the Borexino and GEMMA experiments. We establish that in these experiments the effect can be safely neglected, but it could be accessible to future large-volume neutrino detectors with low energy threshold.

  7. Cluster structure of a low-energy resonance in tetraneutron

    SciTech Connect

    Lashko, Yu. A. Filippov, G. F.

    2008-02-15

    We theoretically investigate the possibility for a tetraneutron to exist as a low-energy resonance state. We explore a microscopic model based on the assumption that the tetraneutron can be treated as a compound system, where {sup 3}n + n and {sup 2}n + {sup 2}n coupled cluster configurations coexist. The influence of the Pauli principle on the kinetic energy of the relative motion of the neutron clusters is shown to result in their attraction. The strength of such attraction is high enough to ensure the existence of a low-energy resonance in the tetraneutron, provided that the oscillator length is large enough.

  8. Diffuse Galactic low energy gamma ray continuum emission

    NASA Technical Reports Server (NTRS)

    Skibo, J. G.; Ramaty, R.

    1993-01-01

    We investigate the origin of diffuse low-energy Galactic gamma-ray continuum down to about 30 keV. We calculate gamma-ray emission via bremsstrahlung and inverse Compton scattering by propagating an unbroken electron power law injection spectrum and employing a Galactic emmissivity model derived from COSB observations. To maintain the low energy electron population capable of producing the observed continuum via bremsstrahlung, a total power input of 4 x 10 exp 41 erg/s is required. This exceeds the total power supplied to the nuclear cosmic rays by about an order of magnitude.

  9. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed. PMID:22540588

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

    NASA Astrophysics Data System (ADS)

    Gaskell, D.

    2013-11-01

    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.

  11. Nitrogen In Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Sittler, E. C.; Johnson, R. E.; McComas, D. J.; Reisenfeld, D.; Shappirio, M. D.; Baragiola, R.; Michael, M.; Shematovich, V. I.; Crary, F.; Young, D. T.

    2004-12-01

    We are analyzing CAPS instrument data on Cassini to look for nitrogen ions in Saturn's magnetosphere. Because Voyager could not separate oxygen and nitrogen, there has been considerable controversy on nitrogen's presence and relative importance. Two principal sources have been suggested: Titan's atmosphere and nitrogen species trapped in Saturn's icy satellite surfaces (Sittler et al 2004). The latter may be primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen ions that have been implanted in the surface (Delitsky and Lane 2002). We will present the results of Saturnian nitrogen cloud modeling and relevant CAPS observations. We recently described the Titan source (Michael, et al. 2004; Shematovich et al. 2003; Smith et al. 2004; Sittler et al. 2004) in preparation for Cassini's Saturnian plasma measurements. Two components were identified: energetic nitrogen ions formed near Titan and energized as they diffused inward (Sittler et al. 2004) and neutrals in orbits with small perigee that became ionized in the inner magnetosphere (Smith et al 2004). The latter component would be a source of lower energy, co-rotating nitrogen ions in the inner magnetosphere. Such a component would have an energy spectrum similar to nitrogen species sputtered from the icy satellite surfaces (Johnson and Sittler 1990). However, the mass spectrum would differ, likely containing NHx and NOx species also, and, hence, may be separated from the Titan source. Our preliminary analysis for nitrogen species in the CAPS data will be compared to our models. Of interest will be the energy spectra, which can indicate whether any nitrogen present is formed locally or near Titan's orbit and diffused inward. This work is supported by the NASA Planetary Atmospheres, NASA Graduate Student Research, Virginia Space Grant Consortium Graduate Research Fellowship and CAPS Cassini instrument team programs.

  12. Enhanced production of low energy electrons by alpha particle impact.

    PubMed

    Kim, Hong-Keun; Titze, Jasmin; Schöffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jörg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schössler, Sven; Ullmann-Pfleger, Klaus; Ulrich, Birte; Fraga, Rui Costa; Petridis, Nikos; Metz, Daniel; Jung, Annika; Grisenti, Robert; Czasch, Achim; Jagutzki, Ottmar; Schmidt, Lothar; Jahnke, Till; Schmidt-Böcking, Horst; Dörner, Reinhard

    2011-07-19

    Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ion-atom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He(+) ions on isolated Ne atoms and on Ne dimers (Ne(2)). In the latter case the Ne atom impacted is surrounded by a most simple environment already opening ICD as a deexcitation channel. As a consequence, we find a dramatically enhanced low energy electron yield. The results suggest that ICD may have a significant influence on cell survival after exposure to ionizing radiation.

  13. Low-energy particle radiation environment at synchronous altitude

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Lens, S. K.

    1972-01-01

    The degradation of thermal control coatings of satellites due to the effects of low energy charged particles in the space environment is discussed. Data obtained from ATS-5 satellite measurement of proton and electron fluxes are presented. The variations in electron density, proton density, and magnetic activity are presented to show correlations which exist between these space factors.

  14. Effective low-energy theory for superconducting topological insulators.

    PubMed

    Hao, Lei; Lee, Ting-Kuo

    2015-03-18

    Candidate pairings of superconducting topological insulators support interesting surface Andreev bound states (SABSs) known as Majorana fermions. As these materials are described by a two-orbital Bernevig-Hughes-Zhang type model, a general understanding of the low-energy physics such as the possible kinds of SABSs are difficult. By virtue of an analogy between a topological insulator and a time reversal invariant topological superconductor, we propose a simple and intuitive method of constructing the low-energy effective models for superconducting topological insulators like CuxBi2Se3. Depending on the value of the chemical potential and for experimentally relevant model parameters, the low-energy properties of these superconductors are shown to be determined by one copy or two copies of single-orbital effective models. If the effective pairing potential shows sign reversal upon reflection by the surface, one Kramers' pair or two Kramers' pairs of SABSs are expected to appear. Explicit analytical calculations in terms of the effective low energy model reproduce the dispersions of the numerically confirmed two pairs of SABSs for a commonly studied pairing.

  15. MEIC Proton Beam Formation with a Low Energy Linac

    SciTech Connect

    Zhang, Yuhong

    2015-09-01

    The MEIC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low-energy protons and ions into the booster ring.

  16. Nuclear phenomena in low-energy nuclear reaction research.

    PubMed

    Krivit, Steven B

    2013-09-01

    This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat.

  17. HEAO-1 analysis of Low Energy Detectors (LED)

    NASA Technical Reports Server (NTRS)

    Nousek, John A.

    1992-01-01

    The activities at Penn State University are described. During the period Oct. 1990 to Dec. 1991 work on HEAO-1 analysis of the Low Energy Detectors (LED) concentrated on using the improved detector spectral simulation model and fitting diffuse x-ray background spectral data. Spectral fitting results, x-ray point sources, and diffuse x-ray sources are described.

  18. Physics overview of the Fermilab Low Energy Antiproton Facility Workshop

    SciTech Connect

    Chanowitz, M.S.

    1986-05-01

    A physics overview is presented of the Fermilab workshop to consider a possible high flux, low energy antiproton facility that would use cooled antiprotons from the accumulator ring of the Tevatron collider. Two examples illustrate the power of each a facility to produce narrow states at high rates. Physics topics to which such a facility may be applied are reviewed.

  19. Mirrored low-energy channel for the MiniXRD

    NASA Astrophysics Data System (ADS)

    Dutra, E. C.; MacNeil, L. P.; Compton, S. M.; Jacoby, B. A.; Raphaelian, M. L.

    2015-08-01

    X-ray Diodes (XRDs) are currently used for spectroscopic measurements, measuring X-ray flux, and estimating spectral shape of the VUV to soft X-ray spectrum. A niche exists for an inexpensive, robust X-ray diode that can be used for experiments in hostile environments on multiple platforms, including explosively driven experiments that have the potential for destroying the diode during the experiment. A multiple channel stacked filtered array was developed with a small field of view where a wider parallel array could not be used, but filtered channels for energies lower than 1000 eV were too fragile to deploy under normal conditions. To achieve both the robustness and the required low-energy detection ability, we designed a small low-energy mirrored channel with a spectral sensitivity from 30 to 1000 eV. The stacked MiniXRD X-ray diode system design incorporates the mirrored low-energy channel on the front of the stacked filtered channels to allow the system to work within a small field of view. We will present results that demonstrate this is a promising solution for low-energy spectrum measurements.

  20. Cochlear implant

    MedlinePlus

    ... implant. These specialists may include: Audiologists Speech therapists Ear, nose, and throat doctors (otolaryngologists) This is a very important part of the process. You will need to work closely with your team of specialists to get ...

  1. Cochlear Implants

    MedlinePlus

    ... additional visits are needed for activating, adjusting, and programming the various electrodes that have been implanted. Also, ... to the center for checkups once the final programming is made to the speech processor. Both children ...

  2. Fast Through-Bond Diffusion of Nitrogen in Silicon

    SciTech Connect

    SCHULTZ,PETER A.; NELSON,JEFFREY S.

    2000-07-12

    The authors report first principles total energy calculations of interaction of nitrogen in silicon with silicon self-interstitials. Substitutional nitrogen captures a silicon interstitial with 3.5 eV binding energy forming a {l_angle}001{r_angle} split interstitial ground state geometry, with the nitrogen forming three bonds. The low energy migration path is through a bond bridge state having two bonds. Fast diffusion of nitrogen occurs through a pure interstitialcy mechanism; the nitrogen never has less than two bonds. Near-zero formation energy of the nitrogen interstitialcy with respect to the substitutional rationalizes the low solubility of substitutional nitrogen in silicon.

  3. Contraceptive implants.

    PubMed

    McDonald-Mosley, Raegan; Burke, Anne E

    2010-03-01

    Implantable contraception has been extensively used worldwide. Implants are one of the most effective and reversible methods of contraception available. These devices may be particularly appropriate for certain populations of women, including women who cannot use estrogen-containing contraception. Implants are safe for use by women with many chronic medical problems. The newest implant, Implanon (Organon International, Oss, The Netherlands), is the only device currently available in the United States and was approved in 2006. It is registered for 3 years of pregnancy prevention. Contraceptive implants have failure rates similar to tubal ligation, and yet they are readily reversible with a return to fertility within days of removal. Moreover, these contraceptive devices can be safely placed in the immediate postpartum period, ensuring good contraceptive coverage for women who may be at risk for an unintended pregnancy. Irregular bleeding is a common side effect for all progestin-only contraceptive implants. Preinsertion counseling should address possible side effects, and treatment may be offered to women who experience prolonged or frequent bleeding.

  4. Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells

    NASA Astrophysics Data System (ADS)

    Yu, L. D.; Wongkham, W.; Prakrajang, K.; Sangwijit, K.; Inthanon, K.; Thongkumkoon, P.; Wanichapichart, P.; Anuntalabhochai, S.

    2013-06-01

    Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.

  5. High-flux source of low-energy neutral beams using reflection of ions from metals

    NASA Technical Reports Server (NTRS)

    Cuthbertson, John W.; Motley, Robert W.; Langer, William D.

    1992-01-01

    Reflection of low-energy ions from surfaces can be applied as a method of producing high-flux beams of low-energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial RF plasma source. The beam provides a large enough flux to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4-32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.

  6. Charge neutralized low energy beam transport at Brookhaven 200 MeV linac

    NASA Astrophysics Data System (ADS)

    Raparia, D.; Alessi, J.; Atoian, G.; Zelenski, A.

    2016-02-01

    The H- magnetron source provides about 100 mA H- beam to be match into the radio-frequency quadrupole accelerator. As H- beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H- beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H- beam from optically pumped polarized ion source.

  7. Charge neutralized low energy beam transport at Brookhaven 200 MeV linac.

    PubMed

    Raparia, D; Alessi, J; Atoian, G; Zelenski, A

    2016-02-01

    The H(-) magnetron source provides about 100 mA H(-) beam to be match into the radio-frequency quadrupole accelerator. As H(-) beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H(-) beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H(-) beam from optically pumped polarized ion source. PMID:26932107

  8. Single ion implantation for solid state quantum computer development

    SciTech Connect

    Schenkel, Thomas; Meijers, Jan; Persaud, Arun; McDonald, Joseph W.; Holder, Joseph P.; Schneider, Dieter H.

    2001-12-18

    Several solid state quantum computer schemes are based on the manipulation of electron and nuclear spins of single donor atoms in a solid matrix. The fabrication of qubit arrays requires the placement of individual atoms with nanometer precision and high efficiency. In this article we describe first results from low dose, low energy implantations and our development of a low energy (<10 keV), single ion implantation scheme for {sup 31}P{sup q+} ions. When {sup 31}P{sup q+} ions impinge on a wafer surface, their potential energy (9.3 keV for P{sup 15+}) is released, and about 20 secondary electrons are emitted. The emission of multiple secondary electrons allows detection of each ion impact with 100% efficiency. The beam spot on target is controlled by beam focusing and collimation. Exactly one ion is implanted into a selected area avoiding a Poissonian distribution of implanted ions.

  9. Improvement of early cell adhesion on Thai silk fibroin surface by low energy plasma.

    PubMed

    Amornsudthiwat, Phakdee; Mongkolnavin, Rattachat; Kanokpanont, Sorada; Panpranot, Joongjai; Wong, Chiow San; Damrongsakkul, Siriporn

    2013-11-01

    Low energy plasma has been introduced to treat the surface of Thai silk fibroin which should be enhanced for cell adhesion due to its native hydrophobic surface. Plasma surface treatment could introduce desirable hydrophilic functionalities on the surface without using any chemicals. In this work, nitrogen glow discharge plasma was generated by a low energy AC50Hz power supply system. The plasma operating conditions were optimized to reach the highest nitrogen active species by using optical emission spectroscopy. X-ray photoelectron spectroscopy (XPS) revealed that amine, hydroxyl, ether, and carboxyl groups were induced on Thai silk fibroin surface after plasma treatment. The results on Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy confirmed that the plasma treated effects were only on the outermost layer since there was no change in the bulk chemistry. The surface topography was insignificantly changed from the detection with atomic force microscopy (AFM). The plasma-treated effects were the improved surface wettability and cell adhesion. After a 90-s treatment, the water contact angle was at 20°, while the untreated surface was at 70°. The early cell adhesion of L929 mouse fibroblast was accelerated. L929 cells only took 3h to reach 100% cell adhesion on 90 s N2 plasma-treated surface, while there was less than 50% cell adhesion on the untreated Thai silk fibroin surface after 6h of culture. The cell adhesion results were in agreement with the cytoskeleton development. L929 F-actin was more evident on 90 s N2 plasma-treated surface than others. It could be concluded that a lower energy AC50Hz plasma system enhanced early L929 mouse fibroblast adhesion on Thai silk fibroin surface without any significant change in surface topography and bulk chemistry. PMID:23893032

  10. Si etching with reactive neutral beams of very low energy

    SciTech Connect

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Iwata, Naotaka; Hara, Tamio

    2014-12-14

    A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

  11. Steering continuum electron dynamics by low-energy attosecond streaking

    NASA Astrophysics Data System (ADS)

    Geng, Ji-Wei; Xiong, Wei-Hao; Xiao, Xiang-Ru; Gong, Qihuang; Peng, Liang-You

    2016-08-01

    A semiclassical model is developed to understand the electronic dynamics in the low-energy attosecond streaking. Under a relatively strong infrared (IR) pulse, the low-energy part of photoelectrons initialized by a single attosecond pulse (SAP) can either rescatter with the ionic core and induce interferences structures in the momentum spectra of the ionized electrons or be recaptured into the Rydberg states. The Coulomb potential plays essential roles in both the electron rescattering and recapturing processes. We find that by changing the time delay between the SAP and the IR pulse, the photoelectrons yield or the population of the Rydberg states can be effectively controlled. The present study demonstrates a fascinating way to steer the electron motion in the continuum.

  12. HIGH POWER OPERATIONS AT THE LOW ENERGY DEMONSTRATION ACCELERATOR (LEDA)

    SciTech Connect

    M. DURAN; V. R. HARRIS

    2001-01-01

    Recently, the Low-Energy Demonstration Accelerator (LEDA) portion of the Accelerator Production of Tritium (APT) project reached its 100-mA, 8-hr continuous wave (CW) beam operation milestone. The LEDA accelerator is a prototype of the low-energy front-end of the linear accelerator (linac) that would have been used in an APT plant. LEDA consists of a 75-keV proton injector, 6.7-MeV, 350-MHz CW radio-frequency quadrupole (RFQ) with associated high-power and low-level RF systems, a short high-energy beam transport (HEBT) and high-power (670-kW CW) beam dump. Details of the LEDA design features will be discussed along with the operational health physics experiences that occurred during the LEDA commissioning phase.

  13. Surface modification using low energy ground state ion beams

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1990-01-01

    A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.

  14. Three dimensional calculation of flux of low energy atmospheric neutrinos

    NASA Technical Reports Server (NTRS)

    Lee, H.; Bludman, S. A.

    1985-01-01

    Results of three-dimensional Monte Carlo calculation of low energy flux of atmospheric neutrinos are presented and compared with earlier one-dimensional calculations 1,2 valid at higher neutrino energies. These low energy neutrinos are the atmospheric background in searching for neutrinos from astrophysical sources. Primary cosmic rays produce the neutrino flux peaking at near E sub=40 MeV and neutrino intensity peaking near E sub v=100 MeV. Because such neutrinos typically deviate by 20 approximately 30 from the primary cosmic ray direction, three-dimensional effects are important for the search of atmospheric neutrinos. Nevertheless, the background of these atmospheric neutrinos is negligible for the detection of solar and supernova neutrinos.

  15. Low-Energy Dynamics in Ultradegenerate QCD Matter

    SciTech Connect

    Schaefer, Thomas; Schwenzer, Kai

    2006-09-01

    We study the low-energy behavior of QCD Green functions in the limit that the baryon chemical potential is much larger than the QCD scale parameter {lambda}{sub QCD}. We show that there is a systematic low-energy expansion in powers of ({omega}/m){sup 1/3}, where {omega} is the energy and m is the screening scale. This expansion is valid even if the effective quark-gluon coupling g is not small. The expansion is purely perturbative in the magnetic regime vertical bar k(vector sign) vertical bar >>k{sub 0}. If the external momenta and energies satisfy vertical bar k(vector sign) vertical bar ={approx}k{sub 0}, planar, Abelian ladder diagrams involving the full quark propagator have to be resummed but the corresponding Dyson-Schwinger equations are closed.

  16. Influence of Packing on Low Energy Vibrations of Densified Glasses

    NASA Astrophysics Data System (ADS)

    Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo

    2013-12-01

    A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.

  17. Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS)

    NASA Technical Reports Server (NTRS)

    Murray, Stephen S.; Pierce, David L. (Technical Monitor)

    2002-01-01

    The Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS) is an astrophysics mission concept for measuring the polarization of X-ray sources at low energies below the C-K band (less than 277 eV). PLEXAS uses the concept of variations in the reflectivity of a multilayered X-ray telescope as a function of the orientation of an X-rays polarization vector with respect to the reflecting surface of the optic. By selecting an appropriate multilayer, and rotating the X-ray telescope while pointing to a source, there will be a modulation in the source intensity, as measured at the focus of the telescope, which is proportional to the degree of polarization in the source.

  18. Low-Energy Electron Beam Direct Writing Equipment

    NASA Astrophysics Data System (ADS)

    Fuse, Takashi; Ando, Atsushi; Kotsugi, Tadashi; Kinoshita, Hidetoshi; Sugihara, Kazuyoshi

    2007-09-01

    We proposed an electron beam direct writing (EBDW) system capable of high throughput and maskless operation based on a novel concept of using both low-energy electron beam (EB) and character projection (CP) system. We fabricated an EB optical column of low-energy EBDW equipment and obtained a resist pattern. We also investigated the beam blur and line width roughness (LWR) of lines and spaces (L/S) formed on a resist to change various EB current densities and convergence half angles. The obtained results show that a Coulomb interaction effect markedly affects the beam blur in our EB optical column. Thus, we reduce the number of sources caused by LWR and developed photoresists to obtain small LWR L/S patterns for achieving a high throughput.

  19. Semiconductor detector performance for low-energy x-rays

    SciTech Connect

    Jaklevic, J.M.; Walton, J.T.; McMurray, R.E. Jr.; Madden, N.W.; Goulding, F.S.

    1987-06-01

    Factors that limit the capabilities of semiconductor detectors at photon energies below 5 keV include energy resolution, detector efficiency, and detector-related continuum background. These properties can be controlled to a certain extent by optimal detector design and fabrication techniques. We describe measurements on the low-energy response of Si(Li) detectors obtained using a tunable, low-energy monochromatic source. Window thicknesses have been measured for a number of devices using different materials for the entry contact. The interpretation of these results in terms of existing detector window models is discussed. Results obtained using a new contact structure demonstrate that a dramatic reduction in window-related absorption in Si(Li) detectors can be achieved.

  20. Status of the Frankfurt low energy electrostatic storage ring (FLSR)

    NASA Astrophysics Data System (ADS)

    King, F.; Kruppi, T.; Müller, J.; Dörner, R.; Schmidt, L. Ph H.; Schmidt-Böcking, H.; Stiebing, K. E.

    2015-11-01

    Frankfurt low-energy storage ring (FLSR) is an electrostatic storage ring for low-energy ions up to q · 80 keV (q being the ion charge state) at Institut für Kernphysik der Goethe-Universität, Frankfurt am Main, Germany. It has especially been designed to provide a basis for experiments on the dynamics of ionic and molecular collisions in complete kinematics, as well as for high precision and time resolved laser spectroscopy. The ring has ‘racetrack’ geometry with a circumference of 14.23 m. It comprises four experimental/diagnostic sections with regions of enhanced ion density (interaction regions). First beam has successfully been stored in FLSR in summer 2013. Since then the performance of the ring has continuously been improved and an electron target for experiments on dissociative recombination has been installed in one of the experimental sections.

  1. Developments in low energy electron beam machinery and processes

    NASA Astrophysics Data System (ADS)

    Nablo, S. V.; Chrusciel, J.; Cleghorn, D. A.; Rangwalla, I.

    2003-08-01

    The engineering and development of a new generation of low energy, high power electron beam equipment is presented. Operating voltages range from 80 to 125 kV at widths to 1.65 m. At 110 kV these systems deliver 1000 Mrad m min -1 at 110 kV. Equipment operating power levels and their impact on reducing equipment size and cost are reviewed. The advantages of electron curing at these reduced operating voltages are described. The principles of the electron beam fluidized bed process for the treatment of powders and particulates in high-speed pneumatic transport are discussed. Typical system performances for polymer dissociation and crosslinking, or for agroproduct disinfestation and disinfection are presented. A process for the sterilization of polymer food containers employing the injection of low energy electrons through the open mouth has been developed. Some of its sterilization capabilities for bottles up to 2 l capacity are described.

  2. Pin diode calibration - beam overlap monitoring for low energy cooling

    SciTech Connect

    Drees, A.; Montag, C.; Thieberger, P.

    2015-09-30

    We were trying to address the question whether or not the Pin Diodes, currently installed approximately 1 meter downstream of the RHIC primary collimators, are suitable to monitor a recombination signal from the future RHIC low energy cooling section. A maximized recombination signal, with the Au+78 ions being lost on the collimator, will indicate optimal Au-electron beam overlap as well as velocity matching of the electron beam in the cooling section.

  3. Photon Strength Function at Low Energies in 95Mo

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Allmond, J. M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Krtička, M.; Lake, P. T.; Larsen, A. C.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-05-01

    A new and model-independent experimental method has been developed to determine the energy dependence of the photon strength function. It is designed to study statistical feeding from the quasi continuum to individual low-lying discrete levels. This new technique is presented and results for 95Mo are compared to data from the University of Oslo. In particular, questions regarding the existence of the low-energy enhancement in the photon strength function are addressed.

  4. Surface conversion techniques for low energy neutral atom imagers

    NASA Technical Reports Server (NTRS)

    Quinn, J. M.

    1995-01-01

    This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

  5. Overview of Light Hydrogen-Based Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Miley, George H.; Shrestha, Prajakti J.

    This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading.

  6. Low-energy gamma rays from Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Roques, J. P.; Mandrou, P.; Lebrun, F.; Paul, J.

    1985-01-01

    The Cyg X-1 was observed by the balloonborne telescope OPALE, in June 1976. The high energy spectrum of the source, which was in its superlow state, was seen to extend well beyond 1 MeV. The observed low energy gamma ray component of Cyg X-1 is compared with the predictions of recent models involving accretion onto a stellar black hole, and including a possible contribution from the pair annihilation 511 keV gamma ray line.

  7. A study of low-energy type II supernovae

    NASA Astrophysics Data System (ADS)

    Lisakov, Sergey M.; Dessart, Luc; Hillier, D. John; Waldman, Roni; Livne, Eli

    2015-08-01

    All stars with an initial mass greater than 8Msun, but not massive enough to encounter the pair-production instability, eventually form a degenerate core and collapse to form a compact object, either a neutron star or a black hole.At the lower mass end, these massive stars die as red-supergiant stars and give rise to Type II supernovae (SNe). The diversity of observed properties of SNe II suggests a range of progenitor mass, radii, but also explosion energy.We have performed a large grid simulations designed to cover this range of progenitor and explosion properties. Using MESA STAR, we compute a set of massive star models (12-30Msun) from the main sequence until core collapse. We then generate explosions with V1D to produce ejecta with a range of explosion energies and yields. Finally, all ejecta are evolved with CMFGEN to generate multi-band light curves and spectra.In this poster, we focus our attention on the properties of low-energy explosions that give rise to low-luminosity Type II Plateau (II-P) SNe. In particular, we present a detailed study of SN 2008bk, but also include other notorious low-energy SNe II-P like 2005cs, emphasising their non-standard properties by comparing to models that match well events like SN 1999em. Such low-energy explosions, characterised by low ejecta expansion rates, are more suitable for reliable spectral line identifications.Based on our models, we discuss the distinct signatures of low-energy explosions in lower and higher mass models. One important goal is to identify whether there is a progenitor-mass bias leading to such events.

  8. Heavy Meson Production at a Low-Energy Photon Collider

    SciTech Connect

    Asztalos, S

    2004-04-15

    A low-energy {gamma}{gamma} collider has been discussed in the context of a testbed for a {gamma}{gamma} interaction region at the Next Linear Collider(NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual {gamma}{gamma} luminosities.

  9. Exchange and relaxation effects in low-energy radiationless transitions

    NASA Technical Reports Server (NTRS)

    Chen, M. H.; Crasemann, B.; Aoyagi, M.; Mark, H.

    1978-01-01

    The effect on low-energy atomic inner-shell Coster-Kronig and super Coster-Kronig transitions that is produced by relaxation and by exchange between the continuum electron and bound electrons was examined and illustrated by specific calculations for transitions that deexcite the 3p vacancy state of Zn. Taking exchange and relaxation into account is found to reduce, but not to eliminate, the discrepancies between theoretical rates and measurements.

  10. Low-energy potential scattering in two and three dimensions

    SciTech Connect

    Khuri, N. N.; Martin, Andre; Richard, J.-M.; Wu, T. T.

    2009-07-15

    Conditions are established for the existence of a scattering length and an effective range in the low-energy expansion of the S-wave phase shift of a central potential in two and three dimensions. The behavior of the phase shift as a function of the momentum is also derived for longer-range power-law potentials which do not fulfill these conditions.

  11. Study of low energy excitations of carbon nanotubes with DMRG

    NASA Astrophysics Data System (ADS)

    Struck, Alexander; Reyes, Sebastian A.; Eggert, Sebastian

    2010-03-01

    We examine the low-energy properties of impure carbon nanotubes including short-ranged electron-electron interactions. In particular, we calculate the local density of states (LDOS) close to selected impurities such as Stone-Wales defect and half-fullerene caps at the tube ends using the density matrix renormalization group (DMRG). We discuss the possibility to identify interaction strength and range from LDOS patterns, which reveal the interplay of electron interactions and impurities.

  12. Low-Energy Monte Carlo and W-Values

    NASA Astrophysics Data System (ADS)

    Grosswendt, B.

    Electrons in the low-energy range of about 1 keV or less play an important role in many fields of radiation research for two reasons: firstly, they are created in large numbers during the passage of all kinds of ionizing radiation through matter, and secondly, they have a linear energy transfer comparable to that of low-energy protons and a-particles, and accordingly they are responsible for the greater part of radiation damage observable in any material. A detailed understanding of the action of low-energy electrons in matter therefore is required in many contexts. In the fields of dosimetry, for example, the determination of the absorbed dose in water or the air kerma is great practical importance, but in most experiments only the amount of ionization produced by secondary electrons within the sensitive volume of a dosimeter can be measured. The results of ionization measurements therefore must converted to quantities based on energy absorption or energy transfer, either by calibration or numerically using an appropriate conversion factor. The most frequently used conversion factor is the so-called W-value, which is the mean energy required to produce an ion pair upon complete slowing down of a charged particle. Its relation to the primary particle kinetic energy T, and to the mean n umber N i of ionizations produced (ionization yield), is given by

  13. A Low energy neutrino factory for large theta(13)

    SciTech Connect

    Geer, Steve; Mena, Olga; Pascoli, Silvia; /Durham U., IPPP

    2007-01-01

    If the value of {theta}{sub 13} is within the reach of the upcoming generation of long-baseline experiments, T2K and NOvA, they show that a low-energy neutrino factory, with peak energy in the few GeV range, would provide a sensitive tool to explore CP-violation and the neutrino mass hierarchy. They consider baselines with typical length 1000-1500 km. The unique performance of the low energy neutrino factory is due to the rich neutrino oscillation pattern at energies between 1 and 4 GeV at baselines {Omicron}(1000) km. They perform both a semi-analytical study of the sensitivities and a numerical analysis to explore how well this setup can measure {theta}{sub 13}, CP-violation, and determine the type of mass hierarchy and the {theta}{sub 23} quadrant. A low energy neutrino factory provides a powerful tool to resolve ambiguities and make precise parameter determinations, for both large and fairly small values of the mixing parameter {theta}{sub 13}.

  14. Electron cooling for low-energy RHIC program

    SciTech Connect

    Fedotov, A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.N.; Pendzick, A.; Satogata, T.

    2009-08-31

    Electron cooling was proposed to increase luminosity of the RHIC collider for heavy ion beam energies below 10 GeV/nucleon. Providing collisions at such energies, termed RHIC 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. The electron cooling system should deliver electron beam of required good quality over energies of 0.9-5 MeV. Several approaches to provide such cooling were considered. The baseline approach was chosen and design work started. Here we describe the main features of the cooling system and its expected performance. We have started design work on a low-energy RHIC electron cooler which will operate with kinetic electron energy range 0.86-2.8 (4.9) MeV. Several approaches to an electron cooling system in this energy range are being investigated. At present, our preferred scheme is to transfer the Fermilab Pelletron to BNL after Tevatron shutdown, and to use it for DC non-magnetized cooling in RHIC. Such electron cooling system can significantly increase RHIC luminosities at low-energy operation.

  15. Colorado School of Mines low energy nuclear physics project

    SciTech Connect

    Cecil, F.E.

    1991-01-02

    A major accomplishment of this project in the past year is the completion of a fairly comprehensive paper describing the survey of radiative capture reactions of protons on light nuclei at low energies. In addition we have completed a preliminary set of measurements of (d,p)/(d,{alpha}) cross section ratios on the charge symmetric nuclei {sup 6}Li and {sup 10}B as a test of the Oppenheimer-Phillips effect. While the {sup 6}Li data remain inconclusive, the {sup 10}B data show solid evidence for the Oppenheimer-Phillips enhancement of the (d,p) reaction relative to the (d,{alpha}) reaction for deuteron bombarding energies below about 100 keV. We have continued our investigation of fusion reaction products from deuterium-metal systems at room temperatures with the startling observation of intense burst of energetic charged particles from deuterium gas loaded thin titaium foils subject to non-equilibrium thermal and electrical conditions. We have completed two projects involving the application of the low energy particle accelerator to material science problems; firstly a study of the transformation of crystalline to amorphous Fe-Zr systems by proton irradiation and secondly the effects of ion bombardment on the critical temperature of YBCO high-temperature superconductors. Finally we have made progress in several instrumentation projects which will be used in some of the up-coming measurements of nuclear cross sections at very low energies.

  16. Can inflation be connected to low energy particle physics?

    SciTech Connect

    Hertzberg, Mark P.

    2012-08-01

    It is an interesting question whether low energy degrees of freedom may be responsible for early universe inflation. To examine this, here we present a simple version of Higgs-inflation with minimal coupling to gravity and a quadratic inflationary potential. This quantitatively differs from the popular non-minimally coupled models, although it is qualitatively similar. In all such models, new heavy fields must enter in order for the theory to be well behaved in the UV. We show that in all cases the Higgs self coupling λ must be quite small in order to integrate out the heavy fields and use the resulting low energy effective field theory of the Higgs to describe inflation. For moderately sized λ, the UV completion is required and will, in general, determine the inflationary regime. We discuss the important issue of the arbitrariness of the Lagrangians used in all these setups by presenting a new class of such models, including a supergravity version. This suggests that the inflationary potential is disconnected from low energy physics.

  17. Structures and Low-Energy Excitations of Amorphous Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Inamura, Yasuhiro; Onoda-Yamamuro, Noriko; Yamamuro, Osamu

    2012-09-01

    We have prepared amorphous clathrate hydrates of Ar, CD4, Xe, and SF6 by depositing mixed vapors of water and guest molecules on a substrate at ca. 10 K. The structure and vibrational density of states were investigated by neutron diffraction and inelastic scattering techniques, respectively. The radial distribution functions of the amorphous hydrates are larger than that of pure amorphous ice in the region around 4 Å (the center-edge distance of the 12-hedral cage), indicating that a local cagelike structure is maintained even in the amorphous solids. The incorporation of the guest molecules decreases the intensity of the phonon excitation below 7 meV, which is known as a low-energy excitation characteristic of amorphous ice. This may be due to the effect that the disorder, defects and distortion producing the low-energy excitation are reduced by a hydrophobic hydration between the guest and water molecules and the resultant hydrogen-bond formation. A similar effect was also observed in the libration mode of water molecules at about 60 meV. The present work has revealed the relation among the local cage formation, hydrogen bonds, and low energy excitations in amorphous hydrates that is the simplest hydrophobic hydration system (H2O--gas mixture).

  18. Low energy description of quantum gravity and complementarity

    NASA Astrophysics Data System (ADS)

    Nomura, Yasunori; Varela, Jaime; Weinberg, Sean J.

    2014-06-01

    We consider a framework in which low energy dynamics of quantum gravity is described preserving locality, and yet taking into account the effects that are not captured by the naive global spacetime picture, e.g. those associated with black hole complementarity. Our framework employs a "special relativistic" description of gravity; specifically, gravity is treated as a force measured by the observer tied to the coordinate system associated with a freely falling local Lorentz frame. We identify, in simple cases, regions of spacetime in which low energy local descriptions are applicable as viewed from the freely falling frame; in particular, we identify a surface called the gravitational observer horizon on which the local proper acceleration measured in the observer's coordinates becomes the cutoff (string) scale. This allows for separating between the "low-energy" local physics and "trans-Planckian" intrinsically quantum gravitational (stringy) physics, and allows for developing physical pictures of the origins of various effects. We explore the structure of the Hilbert space in which the proposed scheme is realized in a simple manner, and classify its elements according to certain horizons they possess. We also discuss implications of our framework on the firewall problem. We conjecture that the complementarity picture may persist due to properties of trans-Planckian physics.

  19. Developing effective rockfall protection barriers for low energy impacts

    NASA Astrophysics Data System (ADS)

    Mentani, Alessio; Giacomini, Anna; Buzzi, Olivier; Govoni, Laura; Gottardi, Guido; Fityus, Stephen

    2016-04-01

    Recently, important progresses have been made towards the development of high capacity rockfall barriers (100 kJ - 8000 kJ). The interest of researchers and practitioners is now turning to the development of fences of minor capacity, whose use becomes essential in areas where rockfall events generally have low intensity and the use of high capacity barriers would be accompanied by excessive costs and high environmental impact. Low energy barriers can also provide a cost-effective solution even in areas where high energies events are expected. Results of full-scale tests are vital to any investigation on the behaviour of these structures. An experimental set-up has been developed at The University of Newcastle (AUS), to investigate the response of low energy rockfall barrier prototypes to low energy impacts. The Australian territory, and in particular New South Wales, is in fact characterised by rockfall events of low-to-medium intensity (50 kJ - 500 kJ) and the need of protection structures working within such energy range, is particularly felt [1]. The experiments involved the impact of a test block onto three spans, low energy barrier prototypes, made of steel structural posts, fully fixed at the base, side cables and a steel meshwork constituted by a double twist hexagonal wire net [2]. Test data enabled the development, calibration and assessment of FE models [3], on which non-linear and dynamic analyses have been performed addressing the effect of the block size. Results have shown that the response of the structure is strongly governed by the net. Data from tests conducted on the sole net and on the entire barrier showed in fact a similar trend, different to what typically observed for high capacity barriers, whose behaviour is also led by the presence of uphill cables and brakes. In particular, the numerical analyses have demonstrated a dependence of the net performance on the block size. In particular, a loss of capacity in the order of 50% occurred as the

  20. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  1. Facial implants.

    PubMed

    Arcuri, M R; Rubenstein, J T

    1998-01-01

    The application of endosseous dental implants for the retention and stabilization of extraoral prostheses and hearing aids has been shown to be effective functionally and aesthetically. Implants have reduced the need for adhesive use, simplifying cleaning procedures and thus extending the life of the prosthesis. Implant-retained prostheses have provided patients the opportunity to participate in routine activities such as work, shopping, swimming, and jogging with less fear of losing their prosthesis. The implants' impact on patients has resulted in their ability to function in society with confidence that their defects will be less noticeable and their ability to respond to the environment enhanced. The culmination of these effects have without doubt improved the overall quality of life for patients. As with any new technology, its application will encounter unanticipated problems and some limitations in use. As the art and science of this technique evolve, however, it is anticipated that it will result in the ability to provide improved health care for patients.

  2. Low-energy tetrahedral polymorphs of carbon, silicon, and germanium

    NASA Astrophysics Data System (ADS)

    Mujica, Andrés; Pickard, Chris J.; Needs, Richard J.

    2015-06-01

    Searches for low-energy tetrahedral polymorphs of carbon and silicon have been performed using density functional theory computations and the ab initio random structure searching approach. Several of the hypothetical phases obtained in our searches have enthalpies that are lower or comparable to those of other polymorphs of group 14 elements that have either been experimentally synthesized or recently proposed as the structure of unknown phases obtained in experiments, and should thus be considered as particularly interesting candidates. A structure of P b a m symmetry with 24 atoms in the unit cell was found to be a low-energy, low-density metastable polymorph in carbon, silicon, and germanium. In silicon, P b a m is found to have a direct band gap at the zone center with an estimated value of 1.4 eV, which suggests applications as a photovoltaic material. We have also found a low-energy chiral framework structure of P 41212 symmetry with 20 atoms per cell containing fivefold spirals of atoms, whose projected topology is that of the so-called Cairo-type two-dimensional pentagonal tiling. We suggest that P 41212 is a likely candidate for the structure of the unknown phase XIII of silicon. We discuss P b a m and P 41212 in detail, contrasting their energetics and structures with those of other group 14 elements, particularly the recently proposed P 42/n c m structure, for which we also provide a detailed interpretation as a network of tilted diamondlike tetrahedra.

  3. Low energy electrons in the inner Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Ganushkina, Natalia; Sillanpaa, Ilkka; Dugyagin, Stepan; Pitchford, David; Rodriguez, Juan; Runov, Andrei

    2016-04-01

    The fluxes of electrons with energies < 100 keV are not usually analyzed and modeled in details when studying the electron radiation belts. These fluxes constitute the low energy part of the seed population, which is critically important for radiation belt dynamics. Moreover, energetic electrons with energies less than about 100 keV are responsible for hazardous space-weather phenomena such as surface charging. The electron flux at these energies varies highly with geomagnetic activity and even during quiet-time periods. Significant variations in the low-energy electrons can be seen during isolated substorms, not related to any storm periods. Moreover, electron flux variations depend on the electron energy. Statistical analysis of AMC 12 CEASE II ESA instrument data (5-50 keV) and GOES MAGED data (40, 75, 150 keV) have revealed that electron fluxes increase by the same order of magnitude during isolated substorms with 200 nT of AE index and storm-time substorms with 1200 nT of AE index. If substorms are represented as electromagnetic pulses which transport and accelerate electrons additionally, how are their amplitudes determined, if not related directly to a substorm's strength? Another factor of crucial importance is the specification of boundary conditions in the electron plasma sheet. We developed a new model for electron number density and temperature in the plasma sheet as dependent on solar wind and IMF conditions based on THEMIS data analysis. We present observational and modeling results on low energy electrons in the inner magnetosphere with newly-developed, time-dependent boundary conditions with a special focus on the role of substorms for electron transport and acceleration.

  4. Low Energy Electrons in the Mars Plasma Environment

    NASA Technical Reports Server (NTRS)

    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 (< 4 keV) electrons will be modeled using the two-stream electron transport code of Link. The code models both external (solar wind) and 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.

  5. Conserved vector current test using low energy beta beams

    SciTech Connect

    Balantekin, A.B.; Jesus, J.H. de; Lazauskas, R.; Volpe, C.

    2006-04-01

    We discuss the possibility of testing the weak currents and, in particular, the weak magnetism term through the measurement of the {nu}{sub e}+p{yields}e{sup +}+n reaction at a low energy beta-beam facility. We analyze the sensitivity using both the total number of events and the angular distribution of the positrons emitted in a water Cerenkov detector. We show that the weak magnetism form factor might be determined with better than several percent accuracy using the angular distribution. This offers a new way of testing the conserved vector current hypothesis.

  6. First experimental research in low energy proton radiography

    NASA Astrophysics Data System (ADS)

    Wei, Tao; Yang, Guo-Jun; Li, Yi-Ding; Long, Ji-Dong; He, Xiao-Zhong; Zhang, Xiao-Ding; Jiang, Xiao-Guo; Ma, Chao-Fan; Zhao, Liang-Chao; Yang, Xing-Lin; Zhang, Zhuo; Wang, Yuan; Pang, Jian; Li, Hong; Li, Wei-Feng; Zhou, Fu-Xin; Shi, Jin-Shui; Zhang, Kai-Zhi; Li, Jin; Zhang, Lin-Wen; Deng, Jian-Jun

    2014-08-01

    Proton radiography is a new scatheless diagnostic tool providing a potential development direction for advanced hydrotesting. Recently a low energy proton radiography system has been developed at the Chinese Academy of Engineering Phyiscs (CAEP). This system has been designed to use an 11 MeV proton beam to radiograph thin static objects. This system consists of a proton cyclotron coupled to an imaging beamline, which is the first domestic beamline dedicated to proton radiography experiments. Via some demonstration experiments, the radiography system is confirmed to provide clear pictures with spatial resolution ~100 μm within 40 mm field-of-view.

  7. GEANT4 simulations for low energy proton computerized tomography.

    PubMed

    Milhoretto, Edney; Schelin, Hugo R; Setti, João A P; Denyak, Valery; Paschuk, Sergei A; Evseev, Ivan G; de Assis, Joaquim T; Yevseyeva, O; Lopes, Ricardo T; Vinagre Filho, Ubirajara M

    2010-01-01

    This work presents the recent results of computer simulations for the low energy proton beam tomographic scanner installed at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to adjust the parameters of previous simulation within the first experimental results and to understand some specific effects that affected the form of the final proton energy spectra. To do this, the energy and angular spread of the initial proton beam were added, and the virtual phantom geometry was specified more accurately in relation to the real one. As a result, a more realistic view on the measurements was achieved.

  8. Study on electron beam in a low energy plasma focus

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  9. Fast self-attenuation determination of low energy gamma lines.

    PubMed

    Haddad, Kh

    2016-09-01

    Linear correlation between self-attenuation factor of 46.5keV ((210)Pb) and the 1764keV, 46.5 counts ratio has been developed in this work using triple superphosphate fertilizer samples. Similar correlation has been also developed for 63.3keV ((238)U). This correlation offers simple, fast, and accurate technique for self-attenuation determination of low energy gamma lines. Utilization of 46.5keV in the ratio has remarkably improved the technique sensitivity in comparison with other work, which used similar concept. The obtained results were used to assess the validity of transmission technique. PMID:27337648

  10. Low energy sputtering of cobalt by cesium ions

    NASA Technical Reports Server (NTRS)

    Handoo, A.; Ray, Pradosh K.

    1989-01-01

    An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.

  11. Mariner-Jupiter-Saturn Low Energy Charged Particle Experiment

    NASA Technical Reports Server (NTRS)

    Peletier, D. P.; Gary, S. A.; Hogrefe, A. F.

    1977-01-01

    The Low Energy Charged Particle Experiment will be launched on the Mariner-Jupiter-Saturn spacecraft in August 1977. The experiment has been designed to perform particle measurements in the intense radiation belts of the Jovian and Saturnian environments, and to provide detailed spectral analysis of both solar and galactic particles in interplanetary space. A single instrument uses 23 solid-state detectors configured in two distinct detector subsystems: one optimized for interplanetary and interstellar measurements, the other for specific particle species, energies, and intensities expected near the planets.

  12. Validation of GPUMCD for low-energy brachytherapy seed dosimetry

    SciTech Connect

    Hissoiny, Sami; Ozell, Benoit; Despres, Philippe; Carrier, Jean-Francois

    2011-07-15

    Purpose: To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on severe approximations, a Monte Carlo based approach would result in more accurate dose calculations, taking in to consideration the patient anatomy as well as interseed attenuation. The first step is to evaluate the capability of GPUMCD to reproduce low-energy, single source, brachytherapy calculations which could ultimately result in fast and accurate, Monte Carlo based, brachytherapy dose calculations for routine planning. Methods: A mixed geometry engine was integrated to GPUMCD capable of handling parametric as well as voxelized geometries. In order to evaluate GPUMCD for brachytherapy calculations, several dosimetry parameters were computed and compared to values found in the literature. These parameters, defined by the AAPM Task-Group No. 43, are the radial dose function, the 2D anisotropy function, and the dose rate constant. These three parameters were computed for two different brachytherapy sources: the Amersham OncoSeed 6711 and the Imagyn IsoStar IS-12501. Results: GPUMCD was shown to yield dosimetric parameters similar to those found in the literature. It reproduces radial dose functions to within 1.25% for both sources in the 0.5< r <10 cm range. The 2D anisotropy function was found to be within 3% at r = 5 cm and within 4% at r = 1 cm. The dose rate constants obtained were within the range of other values reported in the literature.Conclusion: GPUMCD was shown to be able to reproduce various TG-43 parameters for two different low-energy brachytherapy sources found in the literature. The next step is to test GPUMCD as a fast clinical Monte Carlo brachytherapy dose calculations with multiple seeds and patient geometry, potentially providing

  13. Low-energy rotational bands in the nucleus155Eu

    NASA Astrophysics Data System (ADS)

    Katajanheimo, R.; Liljavirta, H.; Siivola, A.; Hammarén, E.; Liukkonen, E.

    1984-02-01

    Excited states in the nucleus155Eu have been produced during in-beam bombardments of a154Sm target with3He beams at 22 and 27 MeV. Decay gamma rays were detected using coincidence equipment optimized for low-energy photons. The level scheme is based on the observed γγ-coincidence relationships combined with the information on relative intensities. Tentatively suggested spin assignments follow from the apparent rotational character of the nucleus. Experimental observations are compared with predictions calculated from a particle-rotor model with a nonspheroidal Woods-Saxon potential.

  14. Development of multichannel low-energy neutron spectrometer

    SciTech Connect

    Arikawa, Y. Nagai, T.; Abe, Y.; Kojima, S.; Sakata, S.; Inoue, H.; Utsugi, M.; Iwasa, Y.; Sarukura, N.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Murata, T.

    2014-11-15

    A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments.

  15. Experimental limit on low energy antiprotons in the cosmic radiation

    NASA Technical Reports Server (NTRS)

    Streitmatter, R. E.; Stochaj, S. J.; Ormes, J. F.; Golden, R. L.; Stephens, S. A.

    1989-01-01

    Results are reported from the Low Energy Antiproton Experiment (LEAP), a balloon-borne instrument which was flown in August, 1987. No evidence of antiproton fluxes is found in the kinetic energy range of 120 MeV to 360 MeV, at the top of the atmosphere. The 90-percent is found confidence upper limit on the antiproton/proton ratio in this energy range is 3.5 x 10 to the -5th. In particular, this new experiment places an upper limit on the flux almost an order of magnitude below the reported flux of Buffington et al. (1981).

  16. RHIC RF Harmonic Numbers for Low Energy Operations

    SciTech Connect

    Satogata,T.

    2008-05-01

    There have been several test runs of RHIC operations to explore the feasibility of luminosity production at low energies. There is considerable international interest in the possible existence of a QCD phase diagram critical point in the RHIC gold-gold collision energy range of {radical}s{sub NN} = 5-50 GeV[l, 2, 3]. This paper reviews the RF harmonic number constraints for RHIC gold-gold collisions in this energy range, and concludes that optimal simultaneous collisions at both experiments are only feasible when the harmonic number is divisible by 9.

  17. Low-energy scattering of electrons and positrons in liquids

    NASA Technical Reports Server (NTRS)

    Schrader, D. M.

    1990-01-01

    The scattering of low energy electrons and positrons is described for the liquid phase and compared and contrasted with that for the gas phase. Similarities as well as differences are noted. The loci of scattering sites, called spurs in the liquid phase, are considered in detail. In particular, their temporal and spatial evolution is considered from the point of view of scattering. Two emphases are made: one upon the stochastic calculation of the distribution of distances required for slowing down to thermal velocities, and the other upon the calculation of cross sections for energy loss by means of quantum mechanics.

  18. Targeting Low-Energy Transfers to Low Lunar Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Anderson, Rodney L.

    2011-01-01

    A targeting scheme is presented to build trajectories from a specified Earth parking orbit to a specified low lunar orbit via a low-energy transfer and up to two maneuvers. The total transfer delta V (velocity) is characterized as a function of the Earth parking orbit inclination and the departure date for transfers to each given low lunar orbit. The transfer delta V (velocity) cost is characterized for transfers constructed to low lunar polar orbits with any longitude of ascending node and for transfers that arrive at the Moon at any given time during a month.

  19. HgI2 low energy beta particle detector

    NASA Technical Reports Server (NTRS)

    Shah, K. S.; Squillante, M. R.; Entine, G.

    1990-01-01

    An HgI2 device structure was designed and tested which allows HgI2 to be used to make low-energy beta-particle detectors. The devices detected tritium beta particles with an efficiency of about 25 percent. A protective encapsulant has been developed which should protect the devices for up to 20 years and will attenuate only a small fraction of the beta particles. It is noted that the devices hold significant promise to provide a practical alternative to liquid scintillation counters and gas flow-through proportional counters.

  20. Shock waves in water at low energy pulsed electric discharges

    NASA Astrophysics Data System (ADS)

    Pinchuk, M. E.; Kolikov, V. A.; Rutberg, Ph G.; Leks, A. G.; Dolinovskaya, R. V.; Snetov, V. N.; Stogov, A. Yu

    2012-12-01

    Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of <=1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

  1. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, James R.; Reich, Morris; Ludewig, Hans; Todosow, Michael

    1999-02-09

    A particle accelerator (12) generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target (14) is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target (14) produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer (44) and a neutron filter (42) are also used for preferentially degrading the secondary particles into a lower energy range if desired.

  2. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, J.R.; Reich, M.; Ludewig, H.; Todosow, M.

    1999-02-09

    A particle accelerator generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer and a neutron filter are also used for preferentially degrading the secondary particles into a lower energy range if desired. 18 figs.

  3. Low energy threshold corrections to neutrino masses and mixing angles

    NASA Astrophysics Data System (ADS)

    Chankowski, P. H.; Wąsowicz, P.

    2002-03-01

    We compute the low energy threshold corrections to neutrino masses and mixing in the standard model (SM) and its minimal supersymmetric version, using the effective theory technique. We demonstrate that they stabilize the results for neutrino masses and mixing with respect to the choice of the scale to which the renormalization group (RG) equation is integrated. (This confirms the correctness of the recent re-derivation of the RGE for the SM in hep-ph/0108005.) Since, as is known, those corrections are potentially very important for phenomenology we derive for them the explicit formulae that can be applied to specific models of neutrino masses and mixing.

  4. Low Energy Lorentz Violation from Modified Dispersion at High Energies.

    PubMed

    Husain, Viqar; Louko, Jorma

    2016-02-12

    Many quantum theories of gravity propose Lorentz-violating dispersion relations of the form ω=|k|f(|k|/M⋆), with recovery of approximate Lorentz invariance at energy scales much below M⋆. We show that a quantum field with this dispersion predicts drastic low energy Lorentz violation in atoms modeled as Unruh-DeWitt detectors, for any f that dips below unity somewhere. As an example, we show that polymer quantization motivated by loop quantum gravity predicts such Lorentz violation below current ion collider rapidities.

  5. Bosonization of the low energy excitations of Fermi liquids

    SciTech Connect

    Castro Neto, A.H.; Fradkin, E. )

    1994-03-07

    We bosonize the low energy excitations of Fermi liquids in any number of dimensions in the limit of long wavelengths. The bosons are a coherent superposition of electron-hole pairs and are related with the displacements of the Fermi surface in some arbitrary direction. A coherent-state path integral for the bosonized theory is derived and it is shown to represent histories of the shape of the Fermi surface. The Landau theory of Fermi liquids can be obtained from the formalism in the absence of nesting of the Fermi surface and singular interactions. We show that the Landau equation for sound waves is exact in the semiclassical approximation for the bosons.

  6. Straight low energy beam transport for intense uranium beams

    NASA Astrophysics Data System (ADS)

    Xiao, C.; Groening, L.; Vormann, H.; Mickat, S.; Hollinger, R.; Adonin, A.; Orzhekhovskaya, A.; Maier, M.; Al-Omari, H.; Barth, W.; Kester, O. K.; Yaramyshev, S.

    2015-07-01

    A new high current uranium ion source and dedicated Low Energy Beam Transport (LEBT) will be built at the GSI High Current Injector (HSI). This LEBT will be integrated into the existing complex which already comprises two branches. The paper presents the design and dynamics simulation using the TRACE-3D and TRACK code. The simulation results illustrate that this straight LEBT can transport uranium beams over a wide range of space-charge compensation, and can provide 15.4 (14.2) mA U4+ inside of the effective acceptance of the subsequent RFQ assuming the space-charge is compensated to 100% (95%).

  7. Low-Energy Hot Plasma and Particles in Saturn's Magnetosphere.

    PubMed

    Krimigis, S M; Armstrong, T P; Axford, W I; Bostrom, C O; Gloeckler, G; Keath, E P; Lanzerotti, L J; Carbary, J F; Hamilton, D C; Roelof, E C

    1982-01-29

    The low-energy charged particle instrument on Voyager 2 measured low-energy electrons and ions (energies greater, similar 22 and greater, similar 28 kiloelectron volts, respectively) in Saturn's magnetosphere. The magnetosphere structure and particle population were modified from those observed during the Voyager 1 encounter in November 1980 but in a manner consistent with the same global morphology. Major results include the following. (i) A region containing an extremely hot ( approximately 30 to 50 kiloelectron volts) plasma was identified and extends from the orbit of Tethys outward past the orbit of Rhea. (ii) The low-energy ion mantle found by Voyager 1 to extend approximately 7 Saturn radii inside the dayside magnetosphere was again observed on Voyager 2, but it was considerably hotter ( approximately 30 kiloelectron volts), and there was an indication of a cooler ( < 20 kiloelectron volts) ion mantle on the nightside. (iii) At energies greater, similar 200 kiloelectron volts per nucleon, H(1), H(2), and H(3) (molecular hydrogen), helium, carbon, and oxygen are important constituents in the Saturnian magnetosphere. The presence of both H(2) and H(3) suggests that the Saturnian ionosphere feeds plasma into the magnetosphere, but relative abundances of the energetic helium, carbon, and oxygen ions are consistent with a solar wind origin. (iv) Low-energy ( approximately 22 to approximately 60 kiloelectron volts) electron flux enhancements observed between the L shells of Rhea and Tethys by Voyager 2 on the dayside were absent during the Voyager 1 encounter. (v) Persistent asymmetric pitch-angle distributions of electrons of 60 to 200 kiloelectron volts occur in the outer magnetosphere in conjunction with the hot ion plasma torus. (vi) The spacecraft passed within approximately 1.1 degrees in longitude of the Tethys flux tube outbound and observed it to be empty of energetic ions and electrons; the microsignature of Enceladus inbound was also observed. (vii

  8. Low-energy control of electrical turbulence in the heart

    NASA Astrophysics Data System (ADS)

    Luther, Stefan; Fenton, Flavio H.; Kornreich, Bruce G.; Squires, Amgad; Bittihn, Philip; Hornung, Daniel; Zabel, Markus; Flanders, James; Gladuli, Andrea; Campoy, Luis; Cherry, Elizabeth M.; Luther, Gisa; Hasenfuss, Gerd; Krinsky, Valentin I.; Pumir, Alain; Gilmour, Robert F.; Bodenschatz, Eberhard

    2011-07-01

    Controlling the complex spatio-temporal dynamics underlying life-threatening cardiac arrhythmias such as fibrillation is extremely difficult, because of the nonlinear interaction of excitation waves in a heterogeneous anatomical substrate. In the absence of a better strategy, strong, globally resetting electrical shocks remain the only reliable treatment for cardiac fibrillation. Here we establish the relationship between the response of the tissue to an electric field and the spatial distribution of heterogeneities in the scale-free coronary vascular structure. We show that in response to a pulsed electric field, E, these heterogeneities serve as nucleation sites for the generation of intramural electrical waves with a source density ρ(E) and a characteristic time, τ, for tissue depolarization that obeys the power law τ~Eα. These intramural wave sources permit targeting of electrical turbulence near the cores of the vortices of electrical activity that drive complex fibrillatory dynamics. We show in vitro that simultaneous and direct access to multiple vortex cores results in rapid synchronization of cardiac tissue and therefore, efficient termination of fibrillation. Using this control strategy, we demonstrate low-energy termination of fibrillation in vivo. Our results give new insights into the mechanisms and dynamics underlying the control of spatio-temporal chaos in heterogeneous excitable media and provide new research perspectives towards alternative, life-saving low-energy defibrillation techniques.

  9. Low energy charged particles interacting with amorphous solid water layers.

    PubMed

    Horowitz, Yonatan; Asscher, Micha

    2012-04-01

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 μA) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 ± 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  10. Low energy charged particles interacting with amorphous solid water layers

    NASA Astrophysics Data System (ADS)

    Horowitz, Yonatan; Asscher, Micha

    2012-04-01

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 μA) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 ± 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  11. New Mechanism of Low Energy Nuclear Reactions Using Superlow

    NASA Astrophysics Data System (ADS)

    Gareev, F. A.; Zhidkova, I. E.

    2006-03-01

    We proposed a new mechanism of LENR (low energy nuclear reactions) cooperative processes in the whole system - nuclei+atoms+condensed matter can occur at smaller threshold than the corresponding ones assoiciated with free constituents. The cooperative processes can be induced and enhanced by (``superlow energy'') external fields. The excess heat is the emission of internal energy, and transmutations from LENR are the result of redistribution of the internal energy of the whole system. A review of possible stimulation mechanisms of LENR is presented. We have concluded that transmutation of nuclei at low energies and excess heat are possible in the framework of the known fundamental physical laws: The universal resonance synchronization principle, and based on it, different enhancement mechanisms of reaction rates are responsible for these processes. The excitation and ionization of atoms may play the role of a trigger for LENR. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0511092 v1 30 Nov 2005. F.A. Gareev, In: FPB-98, Novosibirsk, June 1998, p.92; F.A.Gareev, G.F. Gareeva, in: Novosibirsk, July 2000, p.161. F.A. Gareev, I.E. Zhidkova and Yu.L. Ratis, Preprint JINR P4-2004-68, Dubna, 2004. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0505021 9 May 2005.

  12. MARLEY: Model of Argon Reaction Low Energy Yields

    NASA Astrophysics Data System (ADS)

    Gardiner, Steven; Bilton, Kyle; Grant, Christopher; Pantic, Emilija; Svoboda, Robert

    2015-10-01

    Core-collapse supernovae are sources of tremendous numbers of neutrinos with energies of up to about 50 MeV. In recent years, there has been growing interest in building detectors that are sensitive to supernova neutrinos. Such detectors can provide information about the initial stages of stellar collapse, early warning signals for light emission from supernovae, and opportunities to study neutrino oscillation physics over astronomical distances. In an effort to enable supernova neutrino detection in next-generation experiments like DUNE, the CAPTAIN collaboration plans to make the first direct measurement of cross sections for neutrino interactions on argon in the supernova energy regime. To help predict neutrino event signatures in the CAPTAIN liquid argon time projection chamber (LArTPC), we have developed a first-of-its-kind Monte Carlo event generator called MARLEY (Model of Argon Reaction Low Energy Yields). This generator attempts to model the complicated nuclear structure dependence of low-energy neutrino-nucleus reactions in sufficient detail for use in LArTPC simulations. In this talk we present some preliminary results calculated using MARLEY and discuss how the current version of the generator may be improved and expanded.

  13. Science Considerations for the NPOESS Low Energy Particle Sensor (LEPS)

    NASA Astrophysics Data System (ADS)

    Redus, R.; McGarity, J.; Mullen, E.; Dichter, B.; Evans, D.; Holeman, E.

    2005-12-01

    The Low Energy Particle Sensor (LEPS) to be developed as part of the Space Environment Sensor Suite (SESS) for the NPOESS Spacecraft is a continued enhancement of the SSJ Sensors flown on the Defense Meteorological Satellite Program (DMSP)Spacecraft since 1973. In addition to meeting the operational requirements of the DoD and civilian communities under the oversight of the USAF, NOAA and NASA, the LEPS will continue to provide the science quality data that have been used in hundreds of scientific publications and presentations. An overview of the LEPS instrument will be presented concentrating on the continued requirements for auroral oval boundary determination and auroral energy deposition and auroral particle fluxes over the energy range from 30 eV to 50 keV. Some long-term trend data and selected results of previous investigations from the USAF DMSP and NOAA POES low energy particle data will also be presented. [The science related work is sponsored in part by AFRL under contract F1962802C0086.

  14. TOPICAL REVIEW: RBE of low energy electrons and photons

    NASA Astrophysics Data System (ADS)

    Nikjoo, Hooshang; Lindborg, Lennart

    2010-05-01

    Relative biological effectiveness (RBE) compares the severity of damage induced by a radiation under test at a dose D relative to the reference radiation Dx for the same biological endpoint. RBE is an important parameter in estimation of risk from exposure to ionizing radiation (IR). The present work provides a review of the recently published data and the knowledge of the RBE of low energy electrons and photons. The review presents RBE values derived from experimental data and model calculations including cell inactivation, chromosome aberration, cell transformation, micronuclei formation and induction of double-strand breaks. Biophysical models, including physical features of radiation track, and microdosimetry parameters are presented, analysed and compared with experimental data. The biological effects of low energy electrons and photons are of particular interest in radiation biology as these are strongly absorbed in micrometer and sub-micrometer layers of tissue. RBE values not only depend on the electron and photon energies but also on the irradiation condition, cell type and experimental conditions.

  15. Virtual Compton scattering off the nucleon at low energies

    SciTech Connect

    Scherer, S.; Korchin, A.Y.; Koch, J.H.

    1996-08-01

    We investigate the low-energy behavior of the four-point Green{close_quote}s function {Gamma}{sup {mu}{nu}} describing virtual Compton scattering off the nucleon. Using Lorentz invariance, gauge invariance, and crossing symmetry, we derive the leading terms of an expansion of the operator in the four-momenta {ital q} and {ital q}{sup {prime}} of the initial and final photon, respectively. The model-independent result is expressed in terms of the electromagnetic form factors of the free nucleon, i.e., on-shell information which one obtains from electron-nucleon scattering experiments. Model-dependent terms appear in the operator at {ital O}({ital q}{sub {alpha}}{ital q}{sub {beta}}{sup {prime}}), whereas the orders {ital O}({ital q}{sub {alpha}}{ital q}{sub {beta}}) and {ital O}({ital q}{sub {alpha}}{sup {prime}}{ital q}{sub {beta}}{sup {prime}}) are contained in the low-energy theorem for {Gamma}{sup {mu}{nu}}, i.e., no new parameters appear. We discuss the leading terms of the matrix element and comment on the use of on-shell equivalent electromagnetic vertices in the calculation of {open_quote}{open_quote}Born terms{close_quote}{close_quote} for virtual Compton scattering. {copyright} {ital 1996 The American Physical Society.}

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Einstein - Cartan - Dirac theory in the low-energy limit

    NASA Astrophysics Data System (ADS)

    Singh, P.; Ryder, L. H.

    1997-12-01

    We look for manifestations of the effects of torsion in the low-energy limit in the context of Einstein - Cartan - Dirac theory (or any theory of gravity in which the torsion tensor is purely axial). To proceed, we introduce the mathematical law governing the transport of orthonormal bases or tetrads in a spacetime with torsion. This law is applied to compute the metric and connection in a rotating and accelerating frame, or laboratory. A spin-0264-9381/14/12/031/img1 particle is placed in this rotating and accelerating frame and the low-energy limit of the Dirac equation is taken by means of the Foldy - Wouthuysen transformation. In addition to obtaining the Bonse - Wroblewski phase shift due to acceleration, Sagnac-type effects, rotation - spin couplings of the Mashhoon type, redshift of the kinetic energy and the spin - orbit coupling term of Hehl and Ni, we also obtain several interesting and significant terms as a consequence of introducing torsion into spacetime. We give a detailed interpretation of these additional terms and discuss their observability in the light of current well-known experimental techniques.

  18. Radiative neutralino production in low energy supersymmetric models

    SciTech Connect

    Basu, Rahul; Sharma, Chandradew; Pandita, P. N.

    2008-06-01

    We study the production of the lightest neutralinos in the radiative process e{sup +}e{sup -}{yields}{chi}-tilde{sub 1}{sup 0}{chi}-tilde{sub 1}{sup 0}{gamma} in low energy supersymmetric models for the International Linear Collider energies. This includes the minimal supersymmetric standard model as well as its extension with an additional chiral Higgs singlet superfield, the nonminimal supersymmetric standard model. We compare and contrast the dependence of the signal cross section on the parameters of the neutralino sector of the minimal and nonminimal supersymmetric standard model. We also consider the background to this process coming from the standard model process e{sup +}e{sup -}{yields}{nu}{nu}{gamma}, as well as from the radiative production of the scalar partners of the neutrinos (sneutrinos) e{sup +}e{sup -}{yields}{nu}-tilde{nu}-tilde*{gamma}, which can be a background to the radiative neutralino production when the sneutrinos decay invisibly. In low energy supersymmetric models radiative production of the lightest neutralinos may be the only channel to study supersymmetric partners of the standard model particles at the first stage of a linear collider, since heavier neutralinos, charginos, and sleptons may be too heavy to be pair produced at a e{sup +}e{sup -} machine with {radical}(s)=500 GeV.

  19. Low-Energy Electron Interactions with Complex Targets.

    NASA Astrophysics Data System (ADS)

    Orlando, Thomas

    2006-05-01

    We have examined low-energy electron collisions with complex targets such as pristine nanoscale ice films and water/DNA interfaces by monitoring the reactive scattering processes leading to the formation of H (H^+), H2 (H2^+), O ^3PJ, O ^1D, OH^+, H^+(H2O)n and DNA fragments. This work has shown that temperature-induced changes in the yields are due to subtle geometric and electronic structure changes brought about by changes in the interfacial hydrogen bonding structure. We have then exploited the fact that the two-hole localized states governing cation production and excitations involving a1 levels are good probes of subtle structural changes in the water network. Since low-energy electrons can cause lethal damage to DNA, understanding the role of water and the DNA constituents in the damage event has recently received wide-spread attention. We have modified our multiple scattering ``path approach'' used to describe diffraction effects in stimulated desorption to calculate the diffraction and incident electron intensity at particular sections within a DNA double-strand. This approach assumes hypothetical electron scattering paths inside the target and calculates the interference of all elastically scattered components with the initial incoming wave. Constructive interference at zones localized within the DNA may locally enhance the dissociation probability.

  20. NOSTOS: a spherical TPC to detect low energy neutrinos

    SciTech Connect

    Aune, S.; Colas, P.; Ribas, E. Ferrer; Giomataris, Y.; Irastorza, I. G.; Dolbeau, J.; Gorodetzky, P.; Patzak, T.; Salin, P.; Fanourakis, G.; Geralis, T.; Kousouris, K.; Gounaris, G. J.; Savvidis, I.; Lepeltier, V.; Paschos, E.A.; Vergados, J.D.

    2005-09-08

    A novel low-energy ({approx}few keV) neutrino-oscillation experiment NOSTOS, combining a strong tritium source and a high pressure spherical Time Projection Chamber (TPC) detector 10 m in radius has been recently proposed. The oscillation of neutrinos of such energies occurs within the size of the detector itself, potentially allowing for a very precise (and rather systematics-free) measure of the oscillation parameters, in particular, of the smaller mixing angle {theta}13, which value could be determined for the first time. This detector could also be sensitive to the neutrino magnetic moment and be capable of accurately measure the Weinberg angle at low energy. The same apparatus, filled with high pressure Xenon, exhibits a high sensitivity as a Super Nova neutrino detector with extra galactic sensitivity. The outstanding benefits of the new concept of the spherical TPC will be presented, as well as the issues to be demonstrated in the near future by an ongoing R and D. The very first results of small prototype in operation in Saclay are shown.

  1. Low-energy QCD in the delta regime

    NASA Astrophysics Data System (ADS)

    Matzelle, Matthew E.; Tiburzi, Brian C.

    2016-02-01

    We investigate properties of low-energy QCD in a finite spatial volume, but with arbitrary temperature. In the limit of small temperature and small cube size compared to the pion Compton wavelength, Leutwyler has shown that the effective theory describing low-energy QCD reduces to that of quantum mechanics on the coset manifold, which is the so-called delta regime of chiral perturbation theory. We solve this quantum mechanics analytically for the case of a U (1 )L×U (1 )R subgroup of chiral symmetry, and numerically for the case of S U (2 )L×S U (2 )R . We utilize the quantum mechanical spectrum to compute the mass gap and chiral condensate, and investigate symmetry restoration in a finite spatial volume as a function of temperature. Because we obtain the spectrum for nonzero values of the quark mass, we are able to interpolate between the rigid rotor limit, which emerges at vanishing quark mass, and the harmonic approximation, which is referred to as the p regime. We find that the applicability of perturbation theory about the rotor limit largely requires lighter-than-physical quarks. As a stringent check of our results, we raise the temperature to that of the inverse cube size. When this condition is met, the quantum mechanics reduces to a matrix model. The condensate we obtain in this limit agrees with that determined analytically in the epsilon regime.

  2. Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

    DOE PAGESBeta

    David, Tanya M. S.; Zhang, Cheng; Sun, Sam-Shajing

    2014-01-01

    Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene) or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO) level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO) level of −3.33 eV based on optical energy gap. The polymer wasmore » synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.« less

  3. Low Energy Laser Biostimulation: New Prospects For Medical Applications

    NASA Astrophysics Data System (ADS)

    Castel, John C.; Abergel, R. Patrick; Willner, Robert E.; Baumann, James G.

    1987-03-01

    The therapeutic benefits of light-energy is not a new concept to the modern world. Documented applications from ancient times tell of the therapeutic effects of ordinary sun-light to treat such common ailments as painful body joints, wounds, compound fractures and tetanus. The discovery of laser light in the 1960's, opened up new prospects for the medical use of light. Laser light differs from other forms of electromagnetic spectrum in that a single wavelength rather than a spectrum of wavelengths is emitted. Since the early 1970's, low-energy laser radiation has been reported to enhance wound healing rates, reduce edema, and relieve musculoskeletal pain. There is no detectable thermal effect of this laser on the tissue being treated. The effects are considered to occur as a result of photochemical, non thermal effects of the laser beam. Photons are absorbed by the tissue being treated and, in turn, produce positive therapeutic effects such as reduction of pain and edema. Pre-clinical and clinical evaluations are, presently, underway to document the safety and efficacy of low energy laser therapy, which represents a significant advance in the non-invasive treatment of pain.

  4. Materials for Low-Energy Neutron Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Singleterry, Robert C., Jr.; Thibeault, Sheila A.

    2000-01-01

    Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

  5. Very low energy supernovae and their resulting transients

    NASA Astrophysics Data System (ADS)

    Lovegrove, Elizabeth

    Core-collapse supernovae play a key role in many of astrophysical processes, but the details of how these explosive events work remain elusive. Many questions about the CCSN explosion mechanism and progenitor stars could be answered by either detecting very-low-energy supernovae (VLE SNe) or alternately placing a tight upper bound on their fraction of the CCSN population. However, VLE SNe are by definition dim events. Many VLE SNe result from the failure of the standard CCSN explosion mechanism, meaning that any observable signature must be created by secondary processes either before or during the collapse. In this dissertation I examine alternate means of producing transients in otherwise-failed CCSNe and consider the use of shock breakout flashes to both detect VLE SNe and retrieve progenitor star information. I begin by simulating neutrino-mediated mass loss in CCSNe progenitors to show that a dim, unusual, but still observable transient can be produced. I then simulate shock breakout flashes in VLE SNe for both the purposes of detection as well as extracting information about the exploding star. I discuss particular challenges of modeling shock breakout at low energies and behaviors unique to this regime, in particular the behavior of the spectral temperature. All simulations in this dissertation were done with the CASTRO radiation-hydrodynamic code.

  6. Formation of a high intensity low energy positron string

    NASA Astrophysics Data System (ADS)

    Donets, E. D.; Donets, E. E.; Syresin, E. M.; Itahashi, T.; Dubinov, A. E.

    2004-05-01

    The possibility of a high intensity low energy positron beam production is discussed. The proposed Positron String Trap (PST) is based on the principles and technology of the Electron String Ion Source (ESIS) developed in JINR during the last decade. A linear version of ESIS has been used successfully for the production of intense highly charged ion beams of various elements. Now the Tubular Electron String Ion Source (TESIS) concept is under study and this opens really new promising possibilities in physics and technology. In this report, we discuss the application of the tubular-type trap for the storage of positrons cooled to the cryogenic temperatures of 0.05 meV. It is intended that the positron flux at the energy of 1-5 eV, produced by the external source, is injected into the Tubular Positron Trap which has a similar construction as the TESIS. Then the low energy positrons are captured in the PST Penning trap and are cooled down because of their synchrotron radiation in the strong (5-10 T) applied magnetic field. It is expected that the proposed PST should permit storing and cooling to cryogenic temperature of up to 5×109 positrons. The accumulated cooled positrons can be used further for various physics applications, for example, antihydrogen production.

  7. Surface Coordination of Adatoms by Scanned Low Energy Photoelectron Diffraction

    NASA Astrophysics Data System (ADS)

    Asensio, M. C.

    In this article, a brief overview of the current activity in the field of low energy photoelectron diffraction is presented. Although alternatively angle and energy-scanned photoelectron diffraction can be used to obtain the surface-structural information, we limit our discussion to the low energy and energy-scanned modes and their use in connection with a new developed direct method. By the use of this most recent approach, adatom-substrate distances and adsorption sites are directly revealed from a discrete mapping of the Fourier transform of scanned energy photoelectron diffraction spectra, measured at a representative set of geometries, which depend on the symmetry of the particular studied system. In addition, a short discussion on the determination of the detailed structure of adsorbed overlayers by the traditional trial-and-error method is included, using model multiple scattering calculations. These latest developments are illustrated with a specific example of an atomic adsorbate, and comments about the capabilities and limitations of photoelectron diffraction as a structural technique in new fields.

  8. Low energy charged particles interacting with amorphous solid water layers

    SciTech Connect

    Horowitz, Yonatan; Asscher, Micha

    2012-04-07

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 {mu}A) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 {+-} 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  9. High field - low energy muon ionization cooling channel

    NASA Astrophysics Data System (ADS)

    Kamal Sayed, Hisham; Palmer, Robert B.; Neuffer, David

    2015-09-01

    Muon beams are generated with large transverse and longitudinal emittances. In order to achieve the low emittances required by a muon collider, within the short lifetime of the muons, ionization cooling is required. Cooling schemes have been developed to reduce the muon beam 6D emittances to ≈300 μ m -rad in transverse and ≈1 - 1.5 mm in longitudinal dimensions. The transverse emittance has to be further reduced to ≈50 - 25 μ m -rad with an upper limit on the longitudinal emittance of ≈76 mm in order to meet the high-energy muon collider luminosity requirements. Earlier studies of the transverse cooling of low energy muon beams in high field magnets showed a promising performance, but did not include transverse or longitudinal matching between the stages. In this study we present the first complete design of the high field-low energy ionization cooling channel with transverse and longitudinal matching. The channel design was based on strong focusing solenoids with fields of 25-30 T and low momentum muon beam starting at 135 MeV /c and gradually decreasing. The cooling channel design presented here is the first to reach ≈50 micron scale emittance beam. We present the channel's optimized design parameters including the focusing solenoid fields, absorber parameters and the transverse and longitudinal matching.

  10. Ion implantation of boron in germanium

    SciTech Connect

    Jones, K.S.

    1985-05-01

    Ion implantation of /sup 11/B/sup +/ into room temperature Ge samples leads to a p-type layer prior to any post implant annealing steps. Variable temperature Hall measurements and deep level transient spectroscopy experiments indicate that room temperature implantation of /sup 11/B/sup +/ into Ge results in 100% of the boron ions being electrically active as shallow acceptor, over the entire dose range (5 x 10/sup 11//cm/sup 2/ to 1 x 10/sup 14//cm/sup 2/) and energy range (25 keV to 100 keV) investigated, without any post implant annealing. The concentration of damage related acceptor centers is only 10% of the boron related, shallow acceptor center concentration for low energy implants (25 keV), but becomes dominant at high energies (100 keV) and low doses (<1 x 10/sup 12//cm/sup 2/). Three damage related hole traps are produced by ion implantation of /sup 11/B/sup +/. Two of these hole traps have also been observed in ..gamma..-irradiated Ge and may be oxygen-vacancy related defects, while the third trap may be divacancy related. All three traps anneal out at low temperatures (<300/sup 0/C). Boron, from room temperature implantation of BF/sub 2//sup +/ into Ge, is not substitutionally active prior to a post implant annealing step of 250/sup 0/C for 30 minutes. After annealing additional shallow acceptors are observed in BF/sub 2//sup +/ implanted samples which may be due to fluorine or flourine related complexes which are electrically active.

  11. Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

    NASA Astrophysics Data System (ADS)

    Noël, Céline; Houssiau, Laurent

    2016-05-01

    The structures developed in organic electronics, such as organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) devices always involve hybrid interfaces, joining metal or oxide layers with organic layers. No satisfactory method to probe these hybrid interfaces physical chemistry currently exists. One promising way to analyze such interfaces is to use in situ ion beam etching, but this requires ion beams able to depth profile both inorganic and organic layers. Mono- or diatomic ion beams commonly used to depth profile inorganic materials usually perform badly on organics, while cluster ion beams perform excellently on organics but yield poor results when organics and inorganics are mixed. Conversely, low energy Cs+ beams (<500 eV) allow organic and inorganic materials depth profiling with comparable erosion rates. This paper shows a successful depth profiling of a model hybrid system made of metallic (Au, Cr) and organic (tyrosine) layers, sputtered with 500 eV Cs+ ions. Tyrosine layers capped with metallic overlayers are depth profiled easily, with high intensities for the characteristic molecular ions and other specific fragments. Metallic Au or Cr atoms are recoiled into the organic layer where they cause some damage near the hybrid interface as well as changes in the erosion rate. However, these recoil implanted metallic atoms do not appear to severely degrade the depth profile overall quality. This first successful hybrid depth profiling report opens new possibilities for the study of OLEDs, organic solar cells, or other hybrid devices.

  12. Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions.

    PubMed

    Noël, Céline; Houssiau, Laurent

    2016-05-01

    The structures developed in organic electronics, such as organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) devices always involve hybrid interfaces, joining metal or oxide layers with organic layers. No satisfactory method to probe these hybrid interfaces physical chemistry currently exists. One promising way to analyze such interfaces is to use in situ ion beam etching, but this requires ion beams able to depth profile both inorganic and organic layers. Mono- or diatomic ion beams commonly used to depth profile inorganic materials usually perform badly on organics, while cluster ion beams perform excellently on organics but yield poor results when organics and inorganics are mixed. Conversely, low energy Cs(+) beams (<500 eV) allow organic and inorganic materials depth profiling with comparable erosion rates. This paper shows a successful depth profiling of a model hybrid system made of metallic (Au, Cr) and organic (tyrosine) layers, sputtered with 500 eV Cs(+) ions. Tyrosine layers capped with metallic overlayers are depth profiled easily, with high intensities for the characteristic molecular ions and other specific fragments. Metallic Au or Cr atoms are recoiled into the organic layer where they cause some damage near the hybrid interface as well as changes in the erosion rate. However, these recoil implanted metallic atoms do not appear to severely degrade the depth profile overall quality. This first successful hybrid depth profiling report opens new possibilities for the study of OLEDs, organic solar cells, or other hybrid devices. PMID:26883532

  13. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

  14. Observation of oversaturation-induced defect formation in tungsten irradiated by low energy deuterium ion

    NASA Astrophysics Data System (ADS)

    Jin, Younggil; Song, Jae-Min; Roh, Ki-Baek; Kim, Nam-Kyun; Roh, Hyun-Joon; Jang, Yunchang; Ryu, Sangwon; Bae, Byeongjun; Kim, Gon-Ho

    2016-08-01

    The type of induced material damage in the tungsten irradiated by using deuterium ions was investigated for various value of the fluence at low energy. Experiments were carried out in an electron cyclotron resonance (ECR) plasma source that provided an ion flux of 2.8 × 1021 D 2 + /m2s and a sheath energy of 100 eV/ D 2 + on the tungsten target. The energy of irradiated ions was much smaller than the threshold energy for generating cascade collisional damage (˜ 250 eV) in tungsten and was similar of the plasma at the first wall of KSTAR. The target temperature was kept as 700 - 800 K by using an active cooling system. Secondary ion mass spectroscopy (SIMS) was employed to observe the depth profiles of deuterium. The peak of the trapped deuterium concentration in the irradiated tungsten was located near 16 - 17 nm for 2.0 - 4.0 × 1025 D 2/m2, which is far deeper than the 1.6 nm for ion implantation at 100 eV/ D 2 + ions. Thermal desorption spectroscopy (TDS) data were analyzed to determine the binding energy ( E b = 1.45 eV) of trapped deuterium, which corresponded to an oversaturation-induced vacancy. This observation is very important for understanding the refueling property of the retained deuterium during steady-state fusion plasma operation.

  15. Minimally Invasive Medial Plating of Low-Energy Lisfranc Injuries: Preliminary Experience with Five Cases

    PubMed Central

    del Vecchio, Jorge Javier; Ghioldi, Mauricio; Raimondi, Nicolás; De Elias, Manuel

    2016-01-01

    Fracture dislocations involving the Lisfranc joint are rare; they represent only 0.2% of all the fractures. There is no consensus about the surgical management of these lesions in the medical literature. However, both anatomical reduction and tarsometatarsal stabilization are essential for a good outcome. In this clinical study, five consecutive patients with a diagnosis of Lisfranc low-energy lesion were treated with a novel surgical technique characterized by minimal osteosynthesis performed through a minimally invasive approach. According to the radiological criteria established, the joint reduction was anatomical in four patients, almost anatomical in one patient (#4), and nonanatomical in none of the patients. At the final follow-up, the AOFAS score for the midfoot was 96 points (range, 95–100). The mean score according to the VAS (Visual Analog Scale) at the end of the follow-up period was 1.4 points over 10 (range, 0–3). The surgical technique described in this clinical study is characterized by the use of implants with the utilization of a novel approach to reduce joint and soft tissue damage. We performed a closed reduction and minimally invasive stabilization with a bridge plate and a screw after achieving a closed anatomical reduction. PMID:27340569

  16. Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions.

    PubMed

    Noël, Céline; Houssiau, Laurent

    2016-05-01

    The structures developed in organic electronics, such as organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) devices always involve hybrid interfaces, joining metal or oxide layers with organic layers. No satisfactory method to probe these hybrid interfaces physical chemistry currently exists. One promising way to analyze such interfaces is to use in situ ion beam etching, but this requires ion beams able to depth profile both inorganic and organic layers. Mono- or diatomic ion beams commonly used to depth profile inorganic materials usually perform badly on organics, while cluster ion beams perform excellently on organics but yield poor results when organics and inorganics are mixed. Conversely, low energy Cs(+) beams (<500 eV) allow organic and inorganic materials depth profiling with comparable erosion rates. This paper shows a successful depth profiling of a model hybrid system made of metallic (Au, Cr) and organic (tyrosine) layers, sputtered with 500 eV Cs(+) ions. Tyrosine layers capped with metallic overlayers are depth profiled easily, with high intensities for the characteristic molecular ions and other specific fragments. Metallic Au or Cr atoms are recoiled into the organic layer where they cause some damage near the hybrid interface as well as changes in the erosion rate. However, these recoil implanted metallic atoms do not appear to severely degrade the depth profile overall quality. This first successful hybrid depth profiling report opens new possibilities for the study of OLEDs, organic solar cells, or other hybrid devices.

  17. The use of low energy, ion induced nuclear reactions for proton radiotherapy applications

    SciTech Connect

    Horn, K.M.; Doyle, B.; Segal, M.N.; Hamm, R.W.; Adler, R.J.; Glatstein, E.

    1995-04-01

    Medical radiotherapy has traditionally relied upon the use of external photon beams and internally implanted radioisotopes as the chief means of irradiating tumors. However, advances in accelerator technology and the exploitation of novel means of producing radiation may provide useful alternatives to some current modes of medical radiation delivery with reduced total dose to surrounding healthy tissue, reduced expense, or increased treatment accessibility. This paper will briefly overview currently established modes of radiation therapy, techniques still considered experimental but in clinical use, innovative concepts under study that may enable new forms of treatment or enhance existing ones. The potential role of low energy, ion-induced nuclear reactions in radiotherapy applications is examined specifically for the 650 keV d({sup 3}He,p){sup 4}He nuclear reaction. This examination will describe the basic physics associated with this reaction`s production of 17.4 MeV protons and the processes used to fabricate the necessary materials used in the technique. Calculations of the delivered radiation dose, heat generation, and required exposure times are presented. Experimental data are also presented validating the dose calculations. The design of small, lower cost ion accelerators, as embodied in `nested`-tandem and radio frequency quadrupole accelerators is examined, as is the potential use of high-output {sup 3}He and deuterium ion sources. Finally, potential clinical applications are discussed in terms of the advantages and disadvantages of this technique with respect to current radiotherapy methods and equipment.

  18. Realizing Low-Energy Classification Systems by Implementing Matrix Multiplication Directly Within an ADC.

    PubMed

    Wang, Zhuo; Zhang, Jintao; Verma, Naveen

    2015-12-01

    In wearable and implantable medical-sensor applications, low-energy classification systems are of importance for deriving high-quality inferences locally within the device. Given that sensor instrumentation is typically followed by A-D conversion, this paper presents a system implementation wherein the majority of the computations required for classification are implemented within the ADC. To achieve this, first an algorithmic formulation is presented that combines linear feature extraction and classification into a single matrix transformation. Second, a matrix-multiplying ADC (MMADC) is presented that enables multiplication between an analog input sample and a digital multiplier, with negligible additional energy beyond that required for A-D conversion. Two systems mapped to the MMADC are demonstrated: (1) an ECG-based cardiac arrhythmia detector; and (2) an image-pixel-based facial gender detector. The RMS error over all multiplication performed, normalized to the RMS of ideal multiplication results is 0.018. Further, compared to idealized versions of conventional systems, the energy savings obtained are estimated to be 13× and 29×, respectively, while achieving similar level of performance. PMID:26849205

  19. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition

    SciTech Connect

    Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Bloemen-Van Gurp, Esther; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank

    2010-10-15

    Purpose: The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: {sup 125}I, {sup 103}Pd, {sup 131}Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium D{sub w,m} as opposed to dose to a small mass of medium in medium D{sub m,m}. Methods: Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using {sup 125}I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D{sub 90} values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using {sup 103}Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D{sub 90} values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results: Results from simulation (1) show that variations

  20. Variations of Low-energy Ion Distributions Measured in the Heliosheath

    SciTech Connect

    Decker, R. B.; Roelof, E. C.; Hill, M. E.; Krimigis, S. M.

    2010-12-30

    This report is an update of low-energy ion intensities and angular distributions measured recently by the Low Energy Charged Particle instruments on the Voyager 1 and 2 spacecraft in the inner heliosheath.

  1. Summary of low-energy aspects of QCD and medium-energy hadron parallel sessions

    SciTech Connect

    McClelland, J.B.

    1991-01-01

    Two sessions were organized dealing with low energy aspects of QCD. The first dealt with the issue of QCD dibaryons. The second session centered on mostly low-energy tests of QCD. This report discusses experiments dealing with these sessions.

  2. Short Implants: New Horizon in Implant Dentistry

    PubMed Central

    Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-01-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

  3. Thermal stability study of nitrogen functionalities in a graphene network

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay; Ganguly, Abhijit; Papakonstantinou, Pagona

    2012-06-01

    Catalyst-free vertically aligned graphene nanoflakes possessing a large amount of high density edge planes were functionalized using nitrogen species in a low energy N+ ion bombardment process to achieve pyridinic, cyanide and nitrogen substitution in hexagonal graphitic coordinated units. The evolution of the electronic structure of the functionalized graphene nanoflakes over the temperature range 20-800 °C was investigated in situ, using high resolution x-ray photoemission spectroscopy. We demonstrate that low energy irradiation is a useful tool for achieving nitrogen doping levels up to 9.6 at.%. Pyridinic configurations are found to be predominant at room temperature, while at 800 °C graphitic nitrogen configurations become the dominant ones. The findings have helped to provide an understanding of the thermal stability of nitrogen functionalities in graphene, and offer prospects for controllable tuning of nitrogen doping in device applications.

  4. Ionization efficiency study for low energy nuclear recoils in germanium

    NASA Astrophysics Data System (ADS)

    Barker, D.; Wei, W.-Z.; Mei, D.-M.; Zhang, C.

    2013-08-01

    We used the internal conversion (E0 transition) of germanium-72 to indirectly measure the low energy nuclear recoils of germanium. Together with a reliable Monte Carlo package, in which we implement the internal conversion process, the data was compared to the Lindhard (k = 0.159) and Barker-Mei models. A shape analysis indicates that both models agree well with data in the region of interest within 4%. The most probable value (MPV) of the nuclear recoils obtained from the shape analysis is 17.5 ± 0.12 (sys) ±0.035 (stat) keV with an average path-length of 0.014 μm.

  5. Elastic positron-cadmium scattering at low energies

    SciTech Connect

    Bromley, M. W. J.; Mitroy, J.

    2010-05-15

    The elastic and annihilation cross sections for positron-cadmium scattering are reported up to the positronium-formation threshold (at 2.2 eV). The low-energy phase shifts for the elastic scattering of positrons from cadmium were derived from the bound and pseudostate energies of a very large basis configuration-interaction calculation of the e{sup +}-Cd system. The s-wave binding energy is estimated to be 126{+-}42 meV, with a scattering length of A{sub scat}=(14.2{+-}2.1)a{sub 0}, while the threshold annihilation parameter, Z{sub eff}, was 93.9{+-}26.5. The p-wave phase shift exhibits a weak shape resonance that results in a peak Z{sub eff} of 91{+-}17 at a collision energy of about 490{+-}50 meV.

  6. Xantusiid lizards have low energy, water, and food requirements.

    PubMed

    Mautz, W J; Nagy, K A

    2000-01-01

    Lizards in the family Xantusiidae (the night lizards) are known to have resting metabolic rates that are only half those of other lizards of comparable size. We evaluated whether xantusiids also have low field metabolic rates (FMR) and food requirements by measuring FMR and water flux rates with doubly labeled water in three xantusiid species in their natural habitats. Free-living Xantusia vigilis, Xantusia henshawi, and Xantusia riversiana processed energy and water very slowly, about one-third as fast as do other reptiles of similar size. Xantusiid lizards have a distinctive life history that is characterized by very slow growth and low reproductive rates, and they are intensely reclusive. This general lifestyle is also found in some species that live in environments with scarce food resources, such as in caves and in arid habitats, and these species may also have relatively low energy requirements.

  7. [Low-energy laser therapy in medial tibial stress syndrome].

    PubMed

    Nissen, L R; Astvad, K; Madsen, L

    1994-12-01

    The effect of low-energy laser therapy on shin splints was examined in a randomized study with an unblinded design. Constripts from the Jutland Dragoon regiment with shin splints were given either active laser treatment (40 mW in 60 sec per cm tender tibia edge) or placebo laser. All patients were exempted from normal duty concerning activities like running and march. Forty-nine patients participated in the study, 23 in the laser group and 26 in the control group. From the start the study was designed to be double-blind, but by accident the code was broken towards the end of the study. We found no significant differences between the groups regarding pain visual analog score and readiness to return to active duty after 14 days.

  8. Contamination control and plume assessment of low-energy thrusters

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.

    1993-01-01

    Potential contamination of a spacecraft cryogenic surface by a xenon (Xe) ion generator was evaluated. The analysis involves the description of the plume exhausted from the generator with its relative component fluxes on the spacecraft surfaces, and verification of the conditions for condensation, adsorption, and sputtering at those locations. The data describing the plume fluxes and their effects on surfaces were obtained from two sources: the tests carried out with the Xe generator in a small vacuum chamber to indicate deposits and sputter on monitor slides; and the extensive tests with a mercury (Hg) ion thruster in a large vacuum chamber. The Hg thruster tests provided data on the neutrals, on low-energy ion fluxes, on high-energy ion fluxes, and on sputtered materials at several locations within the plume.

  9. pi+- p differential cross sections at low energies

    SciTech Connect

    H. Denz; P. Amaudruz; J.T. Brack; J. Breitschopf; P. Camerini; J.L. Clark; H. Clement; L. Felawka; E. Fragiacomo; E.F. Gibson; N. Grion; G.J. Hofman; B. Jamieson; E.L. Mathie; R. Meier; G. Moloney; D. Ottewell; O. Patarakin; J.D. Patterson; M.M. Pavan; S. Piano; K. Raywood; R.A. Ristinen; R. Rui; M.E. Sevior; G.R. Smith; J. Stahov; R. Tacik; G.J. Wagner; F. von Wrochem; D.M. Yeomans

    2005-12-03

    Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background suppression, provided simultaneous coverage of a large part of the full angular range, thus allowing very precise relative cross section measurements. The absolute normalization was determined with a typical accuracy of 5 %. This was verified in a simultaneous measurement of muon proton elastic scattering. The measured cross sections show some deviations from phase shift analysis predictions, in particular at large angles and low energies. From the new data we determine the real part of the isospin forward scattering amplitude.

  10. Low-Energy Ions from Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Shayeganrad, G.; Fioretti, A.; Guerri, I.; Tantussi, F.; Ciampini, D.; Allegrini, M.; Viteau, M.; Fuso, F.

    2016-05-01

    We report the features of an ion source based on two-color photoionization of a laser-cooled cesium beam outsourced from a pyramidal magneto-optical trap. The ion source operates in continuous or pulsed mode. At acceleration voltages below 300 V, it delivers some ten ions per bunch with a relative energy spread Δ Urms/U ≃0.032 , as measured through the retarding field-energy-analyzer approach. Space-charge effects are negligible thanks to the low ion density attained in the interaction volume. The performances of the ion beam in a configuration using focused laser beams are extrapolated on the basis of the experimental results. Calculations demonstrate that our low-energy and low-current ion beam can be attractive for the development of emerging technologies requiring the delivery of a small amount of charge, down to the single-ion level and its eventual focusing in the 10-nm range.

  11. Ignitor with stable low-energy thermite igniting system

    DOEpatents

    Kelly, Michael D.; Munger, Alan C.

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  12. ULTRA-LOW-ENERGY HIGH-CURRENT ION SOURCE

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.; Baldwin, David A.

    2009-11-20

    The technical objective of the project was to develop an ultra-low-energy, high-intensity ion source (ULEHIIS) for materials processing in high-technology fields including semiconductors, micro-magnetics and optics/opto-electronics. In its primary application, this ion source can be incorporated into the 4Wave thin-film deposition technique called biased target ion-beam deposition (BTIBD), which is a deposition technique based on sputtering (without magnetic field, i.e., not the typical magnetron sputtering). It is a technological challenge because the laws of space charge limited current (Child-Langmuir) set strict limits of how much current can be extracted from a reservoir of ions, such as a suitable discharge plasma. The solution to the problem was an innovative dual-discharge system without the use of extraction grids.

  13. Status report on the Low Energy Neutron Source for 2015

    NASA Astrophysics Data System (ADS)

    Baxter, D. V.; Rinckel, T.

    2016-11-01

    The Low Energy Neutron Source at Indiana University first produced cold neutrons in April of 2005. Ten years after first reaching this milestone, the facility has three instruments in operation on its cold target station, and a second target station is devoted to thermal and fast neutron physics offers capabilities in radiation effects research (single-event effects in electronics) and radiography. Key elements in our success over these last ten years have been the diversity of activities we have been able maintain (which often involves using each of our instruments for multiple different activities), the close relationship we have developed with a number of major sources, and the focus we have had on innovation in neutron instrumentation. In this presentation, we will introduce some of the highlights from our most recent activities, provide an update on some of our technical challenges, and describe some of our ideas for the future.

  14. Effects of heavy sea quarks at low energies.

    PubMed

    Bruno, Mattia; Finkenrath, Jacob; Knechtli, Francesco; Leder, Björn; Sommer, Rainer

    2015-03-13

    We present a factorization formula for the dependence of light hadron masses and low energy hadronic scales on the mass M of a heavy quark: apart from an overall mass-independent factor Q, ratios such as r_{0}(M)/r_{0}(0) are computable in perturbation theory at large M. The perturbation theory part is stable concerning different loop orders. Our nonperturbative Monte Carlo results obtained in a model calculation, where a doublet of heavy quarks is decoupled, match quantitatively to the perturbative prediction. Upon taking ratios of different hadronic scales at the same mass, the perturbative function drops out and the ratios are given by the decoupled theory up to M^{-2} corrections. We verify-in the continuum limit-that the sea quark effects of quarks with masses around the charm mass are very small in such ratios.

  15. Analysis of a QCD Hamiltonian in the low energy regime.

    NASA Astrophysics Data System (ADS)

    Yépez-Martínez, T.; Amor Quiroz, D. A.; Hess, P. O.; Civitarese, O.

    2016-07-01

    We present a QCD motivated Hamiltonian for the light quark sector. Inspired from self-consistent analysis of the Coulomb interaction, we implement an interaction of the form (-a/r + br) between color sources, which already consider gluonic dynamics by the linear potential contribution. A prediagonalization of the kinetic energy term followed by the implementation of the Tamm-Dancoff method are used to obtain the eigenvalues of the Hamiltonian. A variational analysis is implemented to obtain the optimized basis for the low energy meson spectrum. The potential parameter is compared to the reported lattice string tension with relatively good agreement. The obtained energies are located close to the experimental values and further improvements are discussed.

  16. Bremsstrahlung from nuclear scattering at low energy near a resonance

    NASA Astrophysics Data System (ADS)

    Trail, C. C.; Lesser, P. M. S.; Liou, M. K.

    1984-04-01

    A program to contribute to the general understanding of nuclear reactions by determining as many of the off-shell properties of the proton-nucleus interaction as possible through the study of the proton-nucleus bremsstrahlung process is discussed. The limits of validity of a model independent analysis of these reactions in the neighborhood of a resonance or a breakup threshold are sought. The differences between this analysis and the data is utilized to elucidate those off-shell constraints which any valid proton-nucleus model interaction must satisfy. The bremsstrahlung process provides a method for determining the off-shell properties of the proton-nucleus potential, and the Brooklyn College program offers a unique opportunity to measure these crucial aspects of the low energy proton-nucleus interaction.

  17. HIGH INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON

    SciTech Connect

    Serkan Golge, Bogdan Wojtsekhowski, Branislav Vlahovic

    2012-07-01

    We present a novel concept of a low-energy e{sup +} source with projected intensity on the order of 10{sup 10} slow e{sup +}/s. The key components of this concept are a continuous wave e{sup -} beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e{sup +} into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.

  18. The low energy spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Lamb, F. K.

    1982-01-01

    The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

  19. A New Instrument Design for Imaging Low Energy Neutral Atoms

    NASA Technical Reports Server (NTRS)

    Keller, John W.; Collier, Michael R.; Chornay, Dennis; Rozmarynowski, Paul; Getty, Stephanie; Cooper, John F.; Smith, Billy

    2007-01-01

    The MidSTAR-2 satellite, to be built at the US Naval Academy as a follow-on to the successful MidSTAR-1 satellite (http://web.ew.usna.edu/midstar/), will launch in 2011 and carry three Goddard Space Flight Center (GSFC) experiments developed under Goddard's Internal Research and Development (IRAD) program. One of these GSFC instruments, the Miniature Imager for Neutral Ionospheric atoms and Magnetospheric Electrons (MINI-ME) builds on the heritage of the Goddard-developed Low-Energy Neutral Atom (LENA) imager launched on the IMAGE spacecraft in 2000. MINI-ME features a Venetian-blind conversion surface assembly that improves both light rejection and conversion efficiency in a smaller and lighter package than LENA making this an highly effective instrument for viewing solar wind charge exchange with terrestrial and planetary exospheres. We will describe the MINI-ME prototyping effort and its science targets.

  20. Modeling of human movement monitoring using Bluetooth Low Energy technology.

    PubMed

    Mokhtari, G; Zhang, Q; Karunanithi, M

    2015-01-01

    Bluetooth Low Energy (BLE) is a wireless communication technology which can be used to monitor human movements. In this monitoring system, a BLE signal scanner scans signal strength of BLE tags carried by people, to thus infer human movement patterns within its monitoring zone. However to the extent of our knowledge one main aspect of this monitoring system which has not yet been thoroughly investigated in literature is how to build a sound theoretical model, based on tunable BLE communication parameters such as scanning time interval and advertising time interval, to enable the study and design of effective and efficient movement monitoring systems. In this paper, we proposed and developed a statistical model based on Monte-Carlo simulation, which can be utilized to assess impacts of BLE technology parameters in terms of latency and efficiency, on a movement monitoring system, and can thus benefit a more efficient system design.

  1. Bluetooth low energy: wireless connectivity for medical monitoring.

    PubMed

    Omre, Alf Helge

    2010-03-01

    Electronic wireless sensors could cut medical costs by enabling physicians to remotely monitor vital signs such as blood pressure, blood glucose, and blood oxygenation while patients remain at home. According to the IDC report "Worldwide Bluetooth Semiconductor 2008-2012 Forecast," published November 2008, a forthcoming radio frequency communication ("wireless connectivity") standard, Bluetooth low energy, will link wireless sensors via radio signals to the 70% of cell phones and computers likely to be fitted with the next generation of Bluetooth wireless technology, leveraging a ready-built infrastructure for data transmission. Analysis of trends indicated by this data can help physicians better manage diseases such as diabetes. The technology also addresses the concerns of cost, compatibility, and interoperability that have previously stalled widespread adoption of wireless technology in medical applications.

  2. Advanced satellite sensors: Low Energy Neutral Atom (LENA) imager

    SciTech Connect

    Funsten, H.O.; McComas, D.J.

    1996-09-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Imaging of low energy neutral atoms (LENDs) created by electron capture by magnetospheric plasma ions from interactions with cold geocoronal neutrals promises to be a revolutionary technique for providing unprecedented information about the global structure and dynamics of the terrestrial magnetosphere. This has significant implications in space weather forecasting, weather-induced satellite upset diagnostics, and revolutionary insights into global magnetospheric physics. The Los Alamos Space and Atmospheric Sciences Group has completed extensive neutral atom simulations and detailed instrument definition, and we designed a proof-of-concept demonstration prototype and have obtained externally- funded programs for full instrument development

  3. Low-energy electron-impact ionization of helium

    SciTech Connect

    Schow, E.; Hazlett, K.; Childers, J. G.; Medina, C.; Vitug, G.; Khakoo, M. A.; Bray, I.; Fursa, D. V.

    2005-12-15

    Normalized doubly differential cross sections for the electron-impact ionization of helium at low energies are presented. The data are taken at the incident electron energies of 26.3, 28.3, 30.3, 32.5, 34.3, 36.5, and 40.7 eV and for scattering angles of 10 deg. -130 deg. The measurements involve the use of the moveable target method developed at California State University Fullerton to accurately determine the continuum background in the energy-loss spectra. Normalization of experimental data is made on a relative scale to well-established experimental differential cross sections for excitation of the n=2 manifold of helium and then on an absolute scale to the well-established total ionization cross sections of Shah et al. [J. Phys. B 21, 2751 (1988)]. Comparisons are made with available experimental data and the results of the convergent close-coupling theory.

  4. Linac4 low energy beam measurements with negative hydrogen ions

    NASA Astrophysics Data System (ADS)

    Scrivens, R.; Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-01

    Linac4, a 160 MeV normal-conducting H- linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H- beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  5. Low energy electron magnetometer using a monoenergetic electron beam

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M.; Rayborn, G. H.; White, F. A. (Inventor)

    1983-01-01

    A low energy electron beam magnetometer utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment, atoms in an atomic beam of an inert gas are excited to a Rydberg state and then electrons of near zero energy are detached from the Rydberg atoms. The near zero energy electrons are then accelerated by an electric field V(acc) to form the electron beam. In a second embodiment, a filament emits electrons into an electrostatic analyzer which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

  6. The nuclear structure and low-energy reactions (NSLER) collaboration

    NASA Astrophysics Data System (ADS)

    Dean, D. J.; NSLER Collaboration

    2006-09-01

    The long-term vision of the Nuclear Structure and Low-Energy Reactions (NSLER) collaboration is to arrive at a comprehensive and unified description of nuclei and their reactions that is grounded in the interactions between the constituent nucleons. For this purpose, we will develop a universal energy density functional for nuclei and replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that will deliver maximum predictive power with minimal uncertainties that are well quantified. Nuclear structure and reactions play an essential role in the science to be investigated at rare isotope facilities, and in nuclear physics applications to the Science-Based Stockpile Stewardship Program, next-generation reactors, and threat reduction. We anticipate an expansion of the computational techniques and methods we currently employ, and developments of new treatments, to take advantage of petascale architectures and demonstrate the capability of the leadership class machines to deliver new science heretofore impossible.

  7. Low-energy antinucleon-nucleus interaction revisited

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2015-08-01

    Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with and beams. Interpolating between -nucleus annihilation cross sections with the help of an optical potential to compare with -nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between -nucleus and -nucleus annihilations at very low energies could be possible if cross sections are measured on the same targets and at the same energies as the available cross sections for . Such measurements may be feasible in the foreseeable future.

  8. Oxidation of nickel surfaces by low energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Saric, Iva; Peter, Robert; Kavre, Ivna; Badovinac, Ivana Jelovica; Petravic, Mladen

    2016-03-01

    We have studied formation of oxides on Ni surfaces by low energy oxygen bombardment using X-ray photoemission spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Different oxidation states of Ni ions have been identified in XPS spectra measured around Ni 2p and O 1s core-levels. We have compared our results with thermal oxidation of Ni and shown that ion bombardment is more efficient in creating thin oxide films on Ni surfaces. The dominant Ni-oxide in both oxidation processes is NiO (Ni2+ oxidation state), while some Ni2O3 contributions (Ni3+ oxidation state) are still present in all oxidised samples. The oxide thickness of bombarded Ni samples, as determined by SIMS, was shown to be related to the penetration depth of oxygen ions in Ni.

  9. Modeling of human movement monitoring using Bluetooth Low Energy technology.

    PubMed

    Mokhtari, G; Zhang, Q; Karunanithi, M

    2015-01-01

    Bluetooth Low Energy (BLE) is a wireless communication technology which can be used to monitor human movements. In this monitoring system, a BLE signal scanner scans signal strength of BLE tags carried by people, to thus infer human movement patterns within its monitoring zone. However to the extent of our knowledge one main aspect of this monitoring system which has not yet been thoroughly investigated in literature is how to build a sound theoretical model, based on tunable BLE communication parameters such as scanning time interval and advertising time interval, to enable the study and design of effective and efficient movement monitoring systems. In this paper, we proposed and developed a statistical model based on Monte-Carlo simulation, which can be utilized to assess impacts of BLE technology parameters in terms of latency and efficiency, on a movement monitoring system, and can thus benefit a more efficient system design. PMID:26737430

  10. Maximum Likelihood Analysis of Low Energy CDMS II Germanium Data

    SciTech Connect

    Agnese, R.

    2015-03-30

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from Pb210decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we also perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in our data. Finally, we confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.

  11. Maximum likelihood analysis of low energy CDMS II germanium data

    NASA Astrophysics Data System (ADS)

    Agnese, R.; Anderson, A. J.; Balakishiyeva, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Bowles, M. A.; Brandt, D.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Cerdeno, D. G.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Fritts, M.; Godfrey, G. L.; Golwala, S. R.; Graham, M.; Hall, J.; Harris, H. R.; Hertel, S. A.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Kiveni, M.; Koch, K.; Leder, A.; Loer, B.; Lopez Asamar, E.; Mahapatra, R.; Mandic, V.; Martinez, C.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Moore, D. C.; Nelson, R. H.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.; SuperCDMS Collaboration

    2015-03-01

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using geant4 to simulate the surface-event background from 210Pb decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in our data. We confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.

  12. Space charge effects in the SSC Low Energy Booster

    SciTech Connect

    Machida, S.; Bourianoff, G.; Mahale, N.K.; Mehta, N.; Pilat, F.; Talman, R.; York, R.C.

    1991-05-01

    By means of multi-particle tracking, we explore space charge effects in the Low Energy Booster (LEB) which has a strong requirement for small transverse emittance. Macro-particles are tracked in a self-consistent manner in six dimensional phase space with transverse space charge kicks so that the emittance evolution as well as the particle distribution are simulated as a function of time. Among recent improvements of the code, the longitudinal motion, i.e. synchrotron oscillations as well as acceleration, makes it possible to simulate the capture process of linac microbunches. The code was calibrated by comparing with the experimental results at the Fermilab Booster. Preliminary results of the LEB show slow emittance growth due to the space charge. 5 refs., 5 figs., 1 tab.

  13. Linac4 low energy beam measurements with negative hydrogen ions

    SciTech Connect

    Scrivens, R. Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-15

    Linac4, a 160 MeV normal-conducting H{sup −} linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H{sup −} beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  14. Linac4 low energy beam measurements with negative hydrogen ions.

    PubMed

    Scrivens, R; Bellodi, G; Crettiez, O; Dimov, V; Gerard, D; Granemann Souza, E; Guida, R; Hansen, J; Lallement, J-B; Lettry, J; Lombardi, A; Midttun, Ø; Pasquino, C; Raich, U; Riffaud, B; Roncarolo, F; Valerio-Lizarraga, C A; Wallner, J; Yarmohammadi Satri, M; Zickler, T

    2014-02-01

    Linac4, a 160 MeV normal-conducting H(-) linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H(-) beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  15. Hierarchical fuzzy control of low-energy building systems

    SciTech Connect

    Yu, Zhen; Dexter, Arthur

    2010-04-15

    A hierarchical fuzzy supervisory controller is described that is capable of optimizing the operation of a low-energy building, which uses solar energy to heat and cool its interior spaces. The highest level fuzzy rules choose the most appropriate set of lower level rules according to the weather and occupancy information; the second level fuzzy rules determine an optimal energy profile and the overall modes of operation of the heating, ventilating and air-conditioning system (HVAC); the third level fuzzy rules select the mode of operation of specific equipment, and assign schedules to the local controllers so that the optimal energy profile can be achieved in the most efficient way. Computer simulation is used to compare the hierarchical fuzzy control scheme with a supervisory control scheme based on expert rules. The performance is evaluated by comparing the energy consumption and thermal comfort. (author)

  16. A low energy beam transport system for proton beam

    SciTech Connect

    Yang, Y.; Zhang, Z. M.; Wu, Q.; Zhang, W. H.; Ma, H. Y.; Sun, L. T.; Zhang, X. Z.; Liu, Z. W.; He, Y.; Zhao, H. W.; Xie, D. Z.

    2013-03-15

    A low energy beam transport (LEBT) system has been built for a compact pulsed hadron source (CPHS) at Tsinghua University in China. The LEBT, consisting of two solenoids and three short-drift sections, transports a pulsed proton beam of 60 mA of energy of 50 keV to the entrance of a radio frequency quadrupole (RFQ). Measurement has shown a normalized RMS beam emittance less than 0.2 {pi} mm mrad at the end of the LEBT. Beam simulations were carried out to compare with the measurement and are in good agreement. Based on the successful CPHS LEBT development, a new LEBT for a China ADS projector has been designed. The features of the new design, including a beam chopper and beam simulations of the LEBT are presented and discussed along with CPHS LEBT development in this article.

  17. Scanning ion microscopy with low energy lithium ions.

    PubMed

    Twedt, Kevin A; Chen, Lei; McClelland, Jabez J

    2014-07-01

    Using an ion source based on photoionization of laser-cooled lithium atoms, we have developed a scanning ion microscope with probe sizes of a few tens of nanometers and beam energies from 500eV to 5keV. These beam energies are much lower than the typical operating energies of the helium ion microscope or gallium focused ion beam systems. We demonstrate how low energy can be advantageous in ion microscopy when detecting backscattered ions, due to a decreased interaction volume and the potential for surface sensitive composition analysis. As an example application that demonstrates these advantages, we non-destructively image the removal of a thin residual resist layer during plasma etching in a nano-imprint lithography process.

  18. Low-energy dissociative electron attachment to CF2

    NASA Astrophysics Data System (ADS)

    Chourou, S. T.; Larson, Ã.; Orel, A. E.

    2015-08-01

    We present the results of a theoretical study of dissociative electron attachment (DEA) of low-energy electrons to CF2. We carried out electron scattering calculations using the complex Kohn variational method at the static-exchange and relaxed self-consistent field (SCF) level at the equilibrium geometry and compare our differential cross sections to other results. We then repeated these calculations as a function of the three internal degrees of freedom to obtain the resonance energy surfaces and autoionization widths. We use this data as input to form the Hamiltonian relevant to the nuclear dynamics. The multidimensional wave equation is solved using the multiconfiguration time-dependent Hartree (MCTDH) approach within the local approximation.

  19. Quantifying Low Energy Proton Damage in Multijunction Solar Cells

    NASA Technical Reports Server (NTRS)

    Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Warner, Jeffrey H.; Summers, Geoffrey P.; Lorentzen, Justin R.; Morton, Thomas L.; Taylor, Steven J.

    2007-01-01

    An analysis of the effects of low energy proton irradiation on the electrical performance of triple junction (3J) InGaP2/GaAs/Ge solar cells is presented. The Monte Carlo ion transport code (SRIM) is used to simulate the damage profile induced in a 3J solar cell under the conditions of typical ground testing and that of the space environment. The results are used to present a quantitative analysis of the defect, and hence damage, distribution induced in the cell active region by the different radiation conditions. The modelling results show that, in the space environment, the solar cell will experience a uniform damage distribution through the active region of the cell. Through an application of the displacement damage dose analysis methodology, the implications of this result on mission performance predictions are investigated.

  20. Tierra concrete homes: Low-energy residential building design

    SciTech Connect

    Hayter, S.J.; Torcellini, P.A.; Neimeyer, J.

    1997-12-31

    Using a whole building design concept, Tierra Concrete Homes, a home builder in Pueblo, Colorado, created low-energy, passive solar home designs. Passive solar features incorporated into the designs include house orientation, high-mass walls for thermal storage, exterior insulation, appropriate glazing type combined with overhangs to prevent summer overheating, open interior spaces to maximize daylighting potential, and high efficiency lighting. These ranch-style homes require no cooling and minimum heating equipment to maintain comfortable indoor conditions. They are economically competitive to build, consume little fossil fuel, and produce virtually no construction waste. This paper discusses how the design of one of these homes was optimized to further minimize energy consumption while maintaining an attractive livable environment. It also describes monitoring activities that are currently underway to verify predicted energy consumption.

  1. Low energy ion beam induced changes in ETFE polymer

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; Delalez, N.; de Almeida, A.; Muntele, C.; Muntele, I.; Ila, D.

    2006-01-01

    Low energy ion beam bombardment of ethylenetetrafluoroethylene (ETFE) modifies the physical and chemical properties of the polymer surface in ways that enhance or compromise applications in the technological and medical physics fields. When a material is exposed to ionizing radiation, its changes depends on the type, energy and intensity of the applied radiation. In order to determine the nature of the induced radiation changes, ETFE films were bombarded with fluences from 1012 up to 1015 ions/cm2 of keV N and protons. The emission of gaseous species during the bombardments was monitored with a residual gas analyser (RGA). The bombarded films were analysed with optical absorption photospectrometry (OAP), Fourier transform infrared (FTIR) and micro-Raman spectrometries that determine the chemical nature of the structural changes caused by ions bombardment.

  2. Low energy vibrational excitations characteristic of superionic glass

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Iwase, H.; Arai, M.; Kartini, E.; Russina, M.; Yokoo, T.; Taylor, J. W.

    2006-11-01

    The mechanism of high ionic conductivity in superionic glass constitutes an unsolved problem in the field of science. Here we performed inelastic neutron scattering measurements of superionic glass system (AgI)x(Ag2S)x(AgPO3) by using MARI spectrometer at ISIS, and found that the Q-dependence of inelastic intensity in the energy region from 1 to 3 meV of superionic phase glass shows an excess intensity above Q=1.8 Å-1 compared with insulator phase. Similar phenomena were also observed in another superionic glass (AgI)0.5(AgPO3)0.5 by using NEAT spectrometer at HMI with high resolution measurement. These results clearly suggest peculiar low energy vibrational excitations should be universal features of superionic glass.

  3. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, G.

    1992-01-01

    Milagro is a proposed extensive air shower (EAS) array with a large water Cerenkov detector at its center. It will have a low energy threshold, {approximately} 500 GeV, and good angular resolution, {approximately} 0.4{degrees}. With the large aperture and duty factor of an EAS array, and the energy threshold of an atmospheric Cerenkov telescope, it will be ideally poised to discover new, steady sources of very high energy gamma radiation similar to the Crab nebula, and transient phenomena analogous to the gamma ray bursts seen at lower energies. Here we describe the Milagro detector and give results of tests performed at the CYGNUS array that demonstrate the capabilities of the water Cerenkov technique in detecting and reconstructing extensive air showers.

  4. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, G.; CYGNUS and MILAGRO Collaborations

    1992-10-01

    Milagro is a proposed extensive air shower (EAS) array with a large water Cerenkov detector at its center. It will have a low energy threshold, {approximately} 500 GeV, and good angular resolution, {approximately} 0.4{degrees}. With the large aperture and duty factor of an EAS array, and the energy threshold of an atmospheric Cerenkov telescope, it will be ideally poised to discover new, steady sources of very high energy gamma radiation similar to the Crab nebula, and transient phenomena analogous to the gamma ray bursts seen at lower energies. Here we describe the Milagro detector and give results of tests performed at the CYGNUS array that demonstrate the capabilities of the water Cerenkov technique in detecting and reconstructing extensive air showers.

  5. Low energy ion beam dynamics of NANOGAN ECR ion source

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-04-01

    A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

  6. Low-Energy Impacts onto Lunar Regolith Simulant

    NASA Astrophysics Data System (ADS)

    Seward, Laura M.; Colwell, J.; Mellon, M.; Stemm, B.

    2012-10-01

    Low-Energy Impacts onto Lunar Regolith Simulant Laura M. Seward1, Joshua E. Colwell1, Michael T. Mellon2, and Bradley A. Stemm1, 1Department of Physics, University of Central Florida, Orlando, Florida, 2Southwest Research Institute, Boulder, Colorado. Impacts and cratering in space play important roles in the formation and evolution of planetary bodies. Low-velocity impacts and disturbances to planetary regolith are also a consequence of manned and robotic exploration of planetary bodies such as the Moon, Mars, and asteroids. We are conducting a program of laboratory experiments to study low-velocity impacts of 1 to 5 m/s into JSC-1 lunar regolith simulant, JSC-Mars-1 Martian regolith simulant, and silica targets under 1 g. We use direct measurement of ejecta mass and high-resolution video tracking of ejecta particle trajectories to derive ejecta mass velocity distributions. Additionally, we conduct similar experiments under microgravity conditions in a laboratory drop tower and on parabolic aircraft with velocities as low as 10 cm/s. We wish to characterize and understand the collision parameters that control the outcome of low-velocity impacts into regolith, including impact velocity, impactor mass, target shape and size distribution, regolith depth, target relative density, and crater depth, and to experimentally determine the functional dependencies of the outcomes of low-velocity collisions (ejecta mass and ejecta velocities) on the controlling parameters of the collision. We present results from our ongoing study showing the positive correlation between impact energy and ejecta mass. The total ejecta mass is also dependent on the packing density (porosity) of the regolith. We find that ejecta mass velocity fits a power-law or broken power-law distribution. Our goal is to understand the physics of ejecta production and regolith compaction in low-energy impacts and experimentally validate predictive models for dust flow and deposition. We will present our

  7. Transcanalicular laser dacryocystorhinostomy using low energy 810 nm diode laser

    PubMed Central

    Gupta, Sanjiv K.; Kumar, Ajai; Agarwal, Swati; Pandey, Paritosh

    2012-01-01

    Background: Hypertrophic scarring may be a cause of failure after transcanalicular laser dacryocystorhinostomy (DCR) surgery. This hypertrophic scarring results from tissue charring and excessive coagulation, which may be caused by the high laser energy. We have evaluated the use of low energy settings to prevent hypertrophic scarring, for a successful outcome. Aims: To perform and evaluate transcanalicular laser DCR using low energy 810 nm diode laser. Design: Interventional, non-comparative, case series. Materials and Methods: Patients with nasolacrimal duct obstruction and chronic dacryocystitis, who needed DCR, and were fit for surgery under local anesthesia, were recruited to undergo transcanalicular laser DCR using a 810 nm diode laser. The outcome was measured by the patency of the lacrimal passage, as indicated by the relief in the symptoms and the patency on syringing at the last follow-up. The surgical time and surgical complications were noted. Statistical Analysis Used: Descriptive analysis. Results: The study included 94 patients. The average age was 30.1 years (range 15 - 69 years). Seventy (74.4%) patients were female. Eight patients had failed external DCR. Per-operative patency of the passage was obtained in all the patients. Average surgical time was seven minutes (5 – 18 minutes). At the end of the study period of one year, a successful outcome was seen in 85 patients (90.5%). There were eight patients of previous failed DCR surgeries, and six of them achieved a cure at the end of follow-up. Conclusions: Transcanalicular Laser DCR can be safely performed using a low power 810 nm diode laser. The surgery is elegant, minimally invasive, allows fast rehabilitation, and has an excellent success rate. PMID:23439888

  8. Trapping low-energy antiprotons in an ion trap

    SciTech Connect

    Fei, Xiang.

    1990-01-01

    A fraction of antiprotons from the Low Energy Antiproton Ring (LEAR) of CERN are slowed from 5.9 MeV to below 3 keV as they pass through thin foils. Transmitted particle energy distribution and low energy antiproton yield are measured by a time-of-flight technique. The difference in the range of protons and antiprotons (known as the Barkas effect) is observed. While still in flight, up to 1.3 {times} 10{sup 5} antiprotons with energies between 0 eV to 3 keV are stored in an ion trap from a single pulse of 5.9 MeV antiprotons leaving LEAR, thus a trapping efficiency exceeding of 4 {times} 10{sup {minus}4} is established. Trapped antiprotons maintain their initial energy distribution unless allowed to collide with a cloud of trapped electrons, whereupon they slow and cool below 1 meV in 10 s, and fall into a harmonic potential well suited for precision mass measurements. The slowing, trapping and cooling of antiprotons are the main focus of this thesis. The stored antiprotons are in thermal equilibrium at 4.2 K. In this ion trap, the antiproton cyclotron frequency is measured and compared with the proton (or electron) cyclotron frequency. The new measured ratio of the antiproton and proton inertial masses, with its 4 {times} 10{sup {minus}8} uncertainty, is more than three orders of magnitude more accurate than previous measurements using exotic atoms. This is a most precise test of CPT invariance with baryons. The antiproton lifetime in an ion trap was measured to be more than 103 days by trapping a cloud of antiprotons for 59 days. The indicates the number density of atoms is less than 100/cm{sup 3} which corresponds to the pressure in the vacuum chamber being less than 5 {times} 10{sup {minus}17} Torr at 4.2 K if we apply the ideal gas law.

  9. Study of Genetics and Embryology of Polyembryonic Mutant of Autotetraploid Rice Induced by N+ Beam Implantation

    NASA Astrophysics Data System (ADS)

    Dai, Ximei; Huang, Qunce; Li, Guoping; Hu, Xiuming; Qin, Guangyong; Yu, Zengliang

    2006-11-01

    In the present study autotetraploid rice IR36-4X was treated by an ion implantation technique with nitrogen ion beams. A polyembryonic mutant (named IR36-Shuang) was identified in the M2 generation. The mutant line and its offspring were systematically investigated in regard to their major agronomic properties and the rate of polyembryonic seedling in the M3-M6 generation. The abnormal phenomena in the embryo sac development and the cytological mechanism of the initiation of additional embryo in IR36-Shuang were observed by Laser Scanning Confocal Microscopy. The results were as follows. 1) The plant height, the panicle length and 1000 grain weight of IR36-Shuang were lower than that of its control by 35.41%, 5.08% and 15.72% respectively, Moreover, the setting percentage decreased 12.39% compared with that in normal IR36-4X plants. 2) The polyembryonic trait of IR36-Shuang was genetically stable and the frequency of the polyembryonic seedlings in the IR36-Shuang line was also relatively stable. 3) The rate of abnormal embryo sacs in IR36-Shuang was significantly higher than that in the control IR36-4X. 4) The additional embryo in IR36-Shuang might arise from the double set of embryo sacs in a single ovary, antipodal cells or endosperm cells. These results suggest that IR36-Shuang is a polyembryonic mutant and a new apomixis rice line induced by low energy ion implantation. The prospects for the application in production of the IR36-Shuang line are also discussed. The present study may provide a basis for future investigations of apomixis rice breeding via the ion implantation biotechnology.

  10. Nitrogen In Saturn's Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Sittler, E. C.; Johnson, R. E.; McComas, D.; Reisenfeld, D.; Shappirio, M.; Michael, M.; Shematovich, V. I.; Baragiola, R. A.; Crary, F.; Young, D.

    2004-11-01

    We are analyzing CAPS instrument data on Cassini to look for nitrogen ions in Saturn's magnetosphere. Because Voyager could not separate oxygen and nitrogen, there has been considerable controversy on nitrogen's presence and relative importance. Two principal sources have been suggested: Titan's atmosphere and nitrogen species trapped in Saturn's icy satellite surfaces (Sittler et al 2004). The latter may be primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen ions that have been implanted in the surface (Delitsky and Lane 2002). We will present the results of Saturnian nitrogen cloud modeling and relevant CAPS observations. We recently described the Titan source (Michael, et al. 2004; Shematovich et al. 2003; Smith et al. 2004; Sittler et al. 2004) in preparation for Cassini's Saturnian plasma measurements. Two components were identified: energetic nitrogen ions formed near Titan and energized as they diffused inward (Sittler et al. 2004) and neutrals in orbits with small perigee that became ionized in the inner magnetosphere (Smith et al 2004). The latter component would be a source of lower energy, co-rotating nitrogen ions to the inner magnetosphere. Such a component would have an energy spectrum similar to nitrogen species sputtered from the icy satellite surfaces (Johnson and Sittler 1990). However, the mass spectrum would differ, likely containing NHx and NOx species also, and, hence, may be separated from the Titan source. Our preliminary analysis for nitrogen species in the CAPS data will be compared to the models. Of interest will be the energy spectra, which can indicate whether any nitrogen present is formed locally or near Titan's orbit and diffused inward. This work is supported by the NASA Planetary Atmospheres, NASA Graduate Student Research, Virginia Space Grant Consortium Graduate Research Fellowship and the CAPS Cassini instrument team programs.

  11. Micro-cutting of silicon implanted with hydrogen and post-implantation thermal treatment

    NASA Astrophysics Data System (ADS)

    Jelenković, Emil V.; To, Suet; Sundaravel, B.; Xiao, Gaobo; Huang, Hu

    2016-07-01

    It was reported that non-amorphizing implantation by hydrogen has a potential in improving silicon machining. Post-implantation high-temperature treatment will affect implantation-induced damage, which can have impact on silicon machining. In this article, a relation of a thermal annealing of hydrogen implanted in silicon to micro-cutting experiment is investigated. Hydrogen ions were implanted into 4″ silicon wafers with 175 keV, 150 keV, 125 keV and doses of 2 × 1016 cm-2, 2 × 1016 cm-2 and 3 × 1016 cm-2, respectively. In this way, low hydrogen atom-low defect concentration was created in the region less than ~0.8 μm deep and high hydrogen atom-high defect concentration was obtained at silicon depth of ~0.8-1.5 μm. The post-implantation annealing was carried out at 300 and 400 °C in nitrogen for 1 h. Physical and electrical properties of implanted and annealed samples were characterized by secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), Rutherford backscattering (RBS) and nanoindentation. Plunge cutting experiment was carried out in <110> and <100> silicon crystal direction. The critical depth of cut and cutting force were monitored and found to be influenced by the annealing. The limits of hydrogen implantation annealing contribution to the cutting characteristics of silicon are discussed in light of implantation process and redistribution of hydrogen and defects generation during annealing process.

  12. Study on astrophysical reactions using low-energy RI beams

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hidetoshi

    2009-10-01

    In recent years, low-energy RI beams can be produced in a good intensity and they have been used for studying many astrophysical reactions. One of the facilities producing low-energy RI beams is CRIB (CNS Radio-Isotope Beam separator) [1,2], an RI-beam separator of Center for Nuclear Study, University of Tokyo. Taking CRIB as an example, recent improvements on the RI-beam production and experimental results on astrophysical studies are presented. Several experimental approaches have been taken for the studies on astrophysical reactions.The feature of each method are discussed based on real measurements performed at CRIB. One is the direct method, applied for measurements of reactions such as (α,p) [3]. Another is the measurement of proton/alpha resonance scattering using the thick target method in inverse kinematics, by which we can obtain information on the resonances relevant in astrophysical reactions [4,5]. A recent fruitful result was from a measurement of proton resonance scattering using a ^7Be beam [5]. The energy level structure of ^8B, revealed by the experiment, is especially of interest as it is related with the ^7Be(p,γ) ^8B reaction, responsible for the production of ^8B neutrinos in the sun. We successfully determined parameters of resonances in ^8B below 6.7 MeV, which may affect the ^7Be(p,γ)^8B reaction rate at the solar temparature. Indirect methods, such as ANC and the Trojan Horse Method, were also used in some of the measurements.[4pt] [1] S. Kubono et al., Eur. Phys. J. A13 (2002) 217.[0pt] [2] Y. Yanagisawa et al., Nucl. Instrum. Meth. Phys. Res., Sect. A 539 (2005) 74.[0pt] [3] M. Notani et al., Nucl. Phys. A 764 (2004) 113c.[0pt] [4] T. Teranishi et al., Phys. Lett. B 650 (2007) 129.[0pt] [5] H. Yamaguchi et al., Phys. Lett. B 672 (2009) 230.

  13. Testing SO(10)-inspired leptogenesis with low energy neutrino experiments

    SciTech Connect

    Bari, Pasquale Di; Riotto, Antonio E-mail: Antonio.Riotto@cern.ch

    2011-04-01

    We extend the results of a previous analysis of ours showing that, when both heavy and light flavour effects are taken into account, successful minimal (type I + thermal) leptogenesis with SO(10)-inspired relations is possible. Barring fine tuned choices of the parameters, these relations enforce a hierarchical RH neutrino mass spectrum that results into a final asymmetry dominantly produced by the next-to-lightest RH neutrino decays (N{sub 2} dominated leptogenesis). We present the constraints on the whole set of low energy neutrino parameters. Allowing a small misalignment between the Dirac basis and the charged lepton basis as in the quark sector, the allowed regions enlarge and the lower bound on the reheating temperature gets relaxed to values as low as ∼ 10{sup 10} GeV. It is confirmed that for normal ordering (NO) there are two allowed ranges of values for the lightest neutrino mass: m{sub 1} ≅ (1−5) × 10{sup −3} eV and m{sub 1} ≅ (0.03−0.1) eV. For m{sub 1}∼<0.01 eV the allowed region in the plane θ{sub 13}-θ{sub 23} is approximately given by θ{sub 23}∼<49°+0.65 (θ{sub 13}−5°), while the neutrinoless double beta decay effective neutrino mass falls in the range m{sub ee} = (1−3) × 10{sup −3} eV for θ{sub 13} = (6°−11.5°). For m{sub 1}∼>0.01 eV, one has quite sharply m{sub ee} ≅ m{sub 1} and an upper bound θ{sub 23}∼<46°. These constraints will be tested by low energy neutrino experiments during next years. We also find that inverted ordering (IO), though quite strongly constrained, is not completely ruled out. In particular, we find approximately θ{sub 23} ≅ 43°+12° log (0.2 eV/m{sub 1}), that will be fully tested by future experiments.

  14. Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine.

    PubMed

    Rackwitz, Jenny; Kopyra, Janina; Dąbkowska, Iwona; Ebel, Kenny; Ranković, MiloŠ Lj; Milosavljević, Aleksandar R; Bald, Ilko

    2016-08-22

    2-Fluoroadenine ((2F) A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F) A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA. Information about negative ion resonances and anion-mediated fragmentation reactions is combined with an absolute quantification of DNA strand breaks in (2F) A-containing oligonucleotides upon irradiation with LEEs. The incorporation of (2F) A into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by (2F) A at 5.5, 10, and 15 eV are very similar. Thus, (2F) A can be considered an effective radiosensitizer operative at a wide range of electron energies. PMID:27481662

  15. Collisions of low-energy electrons with cyclohexane.

    PubMed

    Barbosa, Alessandra Souza; Bettega, Márcio H F

    2014-12-28

    We report calculated cross sections for elastic scattering of low-energy electrons by cyclohexane (c-C6H12). We employed the Schwinger multichannel method implemented with norm-conserving pseudopotentials in the static-exchange and static-exchange plus polarization approximations, for impact energies up to 30 eV. We compare our calculated integral cross section with experimental total cross sections available in the literature. We also compare our calculated differential cross sections (DCSs) with experimental results for benzene and experimental and theoretical results for 1,4-dioxane, in order to investigate the similarities between those molecules under electron collisions. Although benzene is a cyclic six-carbon molecule, as cyclohexane, we found that the differential cross sections of the latter are more similar to those of 1,4-dioxane than those of benzene. These similarities suggest that the geometry may play an important role in the behavior of the DCSs of these molecules. Our integral cross section displays a broad structure at around 8.5 eV, in agreement with the total cross section experimental data of 8 eV and vibrational excitation data of 7.5 eV. The present integral cross section also shows the presence of a Ramsauer-Townsend minimum at around 0.12 eV. In general, our integral cross section shows a qualitative agreement with the experimental total cross section.

  16. Rashba scattering in the low-energy limit

    NASA Astrophysics Data System (ADS)

    Hutchinson, Joel; Maciejko, Joseph

    2016-06-01

    We study potential scattering in a two-dimensional electron gas with Rashba spin-orbit coupling in the limit that the energy of the scattering electron approaches the bottom of the lower spin-split band. Focusing on two spin-independent circularly symmetric potentials, an infinite barrier and a delta-function shell, we show that scattering in this limit is qualitatively different from both scattering in the higher spin-split band and scattering of electrons without spin-orbit coupling. The scattering matrix is purely off-diagonal with both off-diagonal elements equal to one, and all angular momentum channels contribute equally; the differential cross section becomes increasingly peaked in the forward and backward scattering directions; the total cross section exhibits quantized plateaus. These features are independent of the details of the scattering potentials, and we conjecture them to be universal. Our results suggest that Rashba scattering in the low-energy limit becomes effectively one-dimensional.

  17. Low energy, high power hydrogen neutral beam for plasma heating

    SciTech Connect

    Deichuli, P.; Davydenko, V.; Ivanov, A. Mishagin, V.; Sorokin, A.; Stupishin, N.; Korepanov, S.; Smirnov, A.

    2015-11-15

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  18. ELISA - an electrostatic storage ring for low-energy ions

    NASA Astrophysics Data System (ADS)

    Pape Moeller, Soeren

    1997-05-01

    The design of a new type of storage ring for low-energy ions using electrostatic deflection and focusing devices is described. Electrostatic bends and quadrupoles are used since they are more efficient than magnetic ones for low-velocity heavy ions. Furthermore, electrostatic devices are more compact and easier to construct than magnetic devices. In comparison to an electromagnetic trap, one important advantage of the elecrostatic ring is the easy access to the circulating beam and its decay products. These and other features, e.g. no magnetic fields, makes such storage devices attractive for many atomic-physics experiments. Also neigboring fields as chemistry and biology might benefit from such an relatively inexpensive device. One important difference between an electrostatic and a magnetic ring is, that the longitudinal energy is not conserved for the electrostatic ring. The actual ring will have a race-track shape as defined by two straight sections each with two quadrupole doublets connected by 180-degrees bends. The bends will consist of 160-degrees spherical deflection plates surrounded by two parallel plate 10-degrees bends. The storage ring ELISA, currently being built, will have a circumference of 6 meters. The first beam tests will take place during summer 1996.

  19. Vacancy-Induced Low-Energy States in Undoped Graphene.

    PubMed

    Sanyal, Sambuddha; Damle, Kedar; Motrunich, Olexei I

    2016-09-01

    We demonstrate that a nonzero concentration n_{v} of static, randomly placed vacancies in graphene leads to a density w of zero-energy quasiparticle states at the band center ε=0 within a tight-binding description with nearest-neighbor hopping t on the honeycomb lattice. We show that w remains generically nonzero in the compensated case (exactly equal number of vacancies on the two sublattices) even in the presence of hopping disorder and depends sensitively on n_{v} and correlations between vacancy positions. For low, but not-too-low, |ε|/t in this compensated case, we show that the density of states ρ(ε) exhibits a strong divergence of the form ρ_{Dyson}(ε)∼|ε|^{-1}/[log(t/|ε|)]^{(y+1)}, which crosses over to the universal low-energy asymptotic form (modified Gade-Wegner scaling) expected on symmetry grounds ρ_{GW}(ε)∼|ε|^{-1}e^{-b[log(t/|ε|)]^{2/3}} below a crossover scale ε_{c}≪t. ε_{c} is found to decrease rapidly with decreasing n_{v}, while y decreases much more slowly. PMID:27661714

  20. [Progress of low-energy shockwave therapy in clinical application].

    PubMed

    Xin, Zhong-cheng; Liu, Jing; Wang, Lin; Li, Hui-xi

    2013-08-18

    A shock wave is a transient pressure disturbance that propagates rapidly in three-dimensional space. It is associated with a sudden rise from ambient pressure to its maximum pressure. Shock wave therapy in urology is primarily used to disintegrate urolithiasis. Recently, low-energy shock wave therapy (LESWT), which is a novel convenient and cost-effective therapeutic modality, is extended to treat other pathological conditions including coronary heart disease, musculoskeletal disorders and erectile dysfunction. However, the exact therapeutic mechanisms and clinical safety and efficacy of LESWT remain to be investigated. Based on the results of previous studies, it is suggested that LESWT could regulate angiogenesis-related growth factors expression including endothelial nitric oxide synthase (eNOS), vessel endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA), which might induce the ingrowth of neovascularization that improves blood supply and increases cell proliferation and eventual tissue regeneration for restore pathological changes. The further studies on cellular and molecular biological changes by LESWT for clarification its mechanism and clinical safety and efficacy studies are recommended.

  1. Options for Production Staging for a Low Energy Neutrino Factory

    SciTech Connect

    Berg J. S.

    2011-10-26

    A low energy neutrino factory (LENF) is defined, for the purpose of this report, to accelerate a muon beam to a total energy in the range of 10-14 GeV, and store it in a decay ring directing a resulting neutrino beam to a detector 2200-2300 km distant. The machine should be ultimately capable of producing 10{sup 21} decays toward that detector per year of 10{sup 7} s. We consider such a neutrino factory to be the accelerator defined in the Interim Design Report (IDR) of the International Design Study for the Neutrino Factory (IDS-NF), modified to remove the final stage of acceleration, possibly modifying the remaining acceleration stages to adjust the final energy, and replacing the decay ring with one designed for the lower energy and shorter baseline. We discuss modifications to that design which would reduce the cost of the machine at the price of a reduction in neutrino production, down to as low as 10{sup 20} decays per year. These modifications will not preclude eventually upgrading the machine to the full production of 10{sup 21} decays per year. The eventual cost of a machine which achieves the full production through a series of lower-production stages should not exceed the cost of a machine which is immediately capable of the full production by more than a small fraction of the cost difference between the full production machine and the lowest production stage.

  2. Addressing Kitchen Contaminants for Healthy, Low-Energy Homes

    SciTech Connect

    Stratton, J. Chris; Singer, Brett C.

    2014-01-01

    Cooking and cooking burners emit pollutants that can adversely affect indoor air quality in residences and significantly impact occupant health. Effective kitchen exhaust ventilation can reduce exposure to cooking-related air pollutants as an enabling step to healthier, low-energy homes. This report identifies barriers to the widespread adoption of kitchen exhaust ventilation technologies and practice and proposes a suite of strategies to overcome these barriers. The recommendations have been vetted by a group of industry, regulatory, health, and research experts and stakeholders who convened for two web-based meetings and provided input and feedback to early drafts of this document. The most fundamental barriers are (1) the common misconception, based on a sensory perception of risk, that kitchen exhaust when cooking is unnecessary and (2) the lack of a code requirement for kitchen ventilation in most US locations. Highest priority objectives include the following: (1) Raise awareness among the public and the building industry of the need to install and routinely use kitchen ventilation; (2) Incorporate kitchen exhaust ventilation as a requirement of building codes and improve the mechanisms for code enforcement; (3) Provide best practice product and use-behavior guidance to ventilation equipment purchasers and installers, and; (4) Develop test methods and performance targets to advance development of high performance products. A specific, urgent need is the development of an over-the-range microwave that meets the airflow and sound requirements of ASHRAE Standard 62.2.

  3. Addressing Kitchen Contaminants for Healthy, Low-Energy Homes

    SciTech Connect

    Stratton, J. Chris; Singer, Brett C.

    2014-01-01

    Cooking and cooking burners emit pollutants that can adversely affect indoor air quality in residences and significantly impact occupant health. Effective kitchen exhaust ventilation can reduce exposure to cooking-related air pollutants as an enabling step to healthier, low-energy homes. This report by Lawrence Berkeley National Laboratory identifies barriers to the widespread adoption of kitchen exhaust ventilation technologies and practice and proposes a suite of strategies to overcome these barriers. The recommendations have been vetted by a group of industry, regulatory, health, and research experts and stakeholders who convened for two meetings and provided input and feedback to early drafts of this document. The most fundamental barriers are (1) the common misconception, based on a sensory perception of risk, that kitchen exhaust when cooking is unnecessary and (2) the lack of a code requirement for kitchen ventilation in most U.S. locations. Highest priority objectives include the following: (1) Raise awareness among the public and the building industry of the need to install and routinely use kitchen ventilation; (2) Incorporate kitchen exhaust ventilation as a requirement of building codes and improve the mechanisms for code enforcement; (3) Provide best practice product and use-behavior guidance to ventilation equipment purchasers and installers, and; (4) Develop test methods and performance targets to advance development of high performance products. A specific, urgent need is the development of an over-the-range microwave that meets the airflow and sound requirements of ASHRAE Standard 62.2.

  4. A compact, versatile low-energy electron beam ion source

    SciTech Connect

    Zschornack, G.; König, J.; Schmidt, M.; Thorn, A.

    2014-02-15

    A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

  5. Theories of Variable Mass Particles and Low Energy Nuclear Phenomena

    NASA Astrophysics Data System (ADS)

    Davidson, Mark

    2014-02-01

    Variable particle masses have sometimes been invoked to explain observed anomalies in low energy nuclear reactions (LENR). Such behavior has never been observed directly, and is not considered possible in theoretical nuclear physics. Nevertheless, there are covariant off-mass-shell theories of relativistic particle dynamics, based on works by Fock, Stueckelberg, Feynman, Greenberger, Horwitz, and others. We review some of these and we also consider virtual particles that arise in conventional Feynman diagrams in relativistic field theories. Effective Lagrangian models incorporating variable mass particle theories might be useful in describing anomalous nuclear reactions by combining mass shifts together with resonant tunneling and other effects. A detailed model for resonant fusion in a deuterium molecule with off-shell deuterons and electrons is presented as an example. Experimental means of observing such off-shell behavior directly, if it exists, is proposed and described. Brief explanations for elemental transmutation and formation of micro-craters are also given, and an alternative mechanism for the mass shift in the Widom-Larsen theory is presented. If variable mass theories were to find experimental support from LENR, then they would undoubtedly have important implications for the foundations of quantum mechanics, and practical applications may arise.

  6. Resonant Electromagnetic Interaction in Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Chubb, Scott

    2008-03-01

    Basic ideas about how resonant electromagnetic interaction (EMI) can take place in finite solids are reviewed. These ideas not only provide a basis for conventional, electron energy band theory (which explains charge and heat transport in solids), but they also explain how through finite size effects, it is possible to create many of the kinds of effects envisioned by Giuliano Preparata. The underlying formalism predicts that the orientation of the external fields in the SPAWAR protocolootnotetextKrivit, Steven B., New Energy Times, 2007, issue 21, item 10. http://newenergytimes.com/news/2007/NET21.htm^,ootnotetextSzpak, S.; Mosier-Boss, P.A.; Gordon, F.E. Further evidence of nuclear reactions in the Pd lattice: emission of charged particles. Naturwissenschaften 94,511(2007)..has direct bearing on the emission of high-energy particles. Resonant EMI also implies that nano-scale solids, of a particular size, provide an optimal environment for initiating Low Energy Nuclear Reactions (LENR) in the PdD system.

  7. A high intensity dc H- source for low energy injection

    NASA Astrophysics Data System (ADS)

    Kuo, T.; Baartman, R.; Dutto, G.; Hahto, S.; ńrje, J.; Liukkonen, E.

    2002-02-01

    While a 20 mA dc H- source system at 25-30 keV beam energy has been developed at TRIUMF several years ago, another recent demand on the system is to provide a 4 to 5 mA H- at the 4-6 keV energy range. We found that at this low energy range, the existing source/extraction system can only give ˜1 mA with poor emittance due to strong space-charge effect. Fortunately, a very special source/extraction mechanism together with the use of neutralization was discovered and developed to overcome this difficulty. Up to 4 mA with a normalized rms emittance of 0.15 π mm mr has been achieved at 6 keV. This performance finds its usefulness for injection systems where lower beam energy and higher beam intensity are required. A copy of the TRIUMF system was constructed and successfully tested in the summer of 2000 for the "H- Acceleration Project" for the K130 cyclotron at Jyväskylä University, Finland.

  8. Low energy booster radio frequency cavity structural analysis

    SciTech Connect

    Jones, K.

    1993-04-01

    The structural design of the Superconducting Super Collider Low Energy Booster (LEB) Radio Frequency (RF) Cavity is very unique. The cavity is made of three different materials which all contribute to its structural strength while at the same time providing a good medium for magnetic properties. Its outer conductor is made of thin walled stainless steel which is later copper plated to reduce the electrical losses. Its tuner housing is made of a fiber reinforced composite laminate, similar to G10, glued to stainless steel plating. The stainless steel of the tuner is slotted to significantly diminish the magnetically-induced eddy currents. The composite laminate is bonded to the stainless steel to restore the structural strength that was lost in slotting. The composite laminate is also a barrier against leakage of the pressurized internal ferrite coolant fluid. The cavity`s inner conductor, made of copper and stainless steel, is subjected to high heat loads and must be liquid cooled. The requirements of the Cavity are very stringent and driven primarily by deflection, natural frequency and temperature. Therefore, very intricate finite element analysis was used to complement conventional hand analysis in the design of the cavity. Structural testing of the assembled prototype cavity is planned to demonstrate the compliance of the cavity design to all of its requirements.

  9. Rydberg phases of Hydrogen and low energy nuclear reactions

    NASA Astrophysics Data System (ADS)

    Olafsson, Sveinn; Holmlid, Leif

    2016-03-01

    For over the last 26 years the science of cold fusion/LENR has been researched around the world with slow pace of progress. Modest quantity of excess heat and signatures of nuclear transmutation and helium production have been confirmed in experiments and theoretical work has only resulted in a large flora of inadequate theoretical scenarios. Here we review current state of research in Rydberg matter of Hydrogen that is showing strong signature of nuclear processes. In the presentation experimental behavior of Rydberg matter of hydrogen is described. An extensive collaboration effort of surface physics, catalysis, atomic physics, solid state physics, nuclear physics and quantum information is need to tackle the surprising experimental results that have so far been obtained. Rydberg matter of Hydrogen is the only known state of matter that is able to bring huge collection of protons to so short distances and for so long time that tunneling becomes a reasonable process for making low energy nuclear reactions. Nuclear quantum entanglement can also become realistic process at theses conditions.

  10. Low energy electrons and swift ion track structure in PADC

    DOE PAGESBeta

    Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.; Champion, Christophe

    2015-05-27

    The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particularmore » incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.« less

  11. Heliosphere Instrument for Spectra, Composition and Anisotropy at Low Energies

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Gold, R. E.; Anderson, K. A.; Armstrong, T. P.; Lin, R. P.; Krimigis, S. M.; Pick, M.; Roelof, E. C.; Sarris, E. T.; Simnett, G. M.

    1992-01-01

    The Heliosphere Instrument for Spectra, Composition, and Anisotropy at Low Energies (HI-SCALE) is designed to make measurements of interplanetary ions and electrons throughout the entire Ulysses mission. The ions (E(i) greater than about 50 keV) and electrons (E(e) greater than about 30 keV) are identified uniquely and detected by five separate solid-state detector telescopes that are oriented to give nearly complete pitch-angle coverage from the spinning spacecraft. Ion elemental abundances are determined by Delta E vs E telescope using a thin (5 microns) front solid state detector element in a three-element telescope. Experimental operation is controlled by a microprocessor-based data system. Inflight calibration is provided by radioactive sources mounted on telescope covers which can be closed for calibration purposes and for radiation protection during the course of the mission. Ion and electron spectral information is determined using both broad-energy-range rate channels and a 32 channel pulse-height analyzer for more detailed spectra. Some initial in-ecliptic measurements are presented which demonstrate the features of the instrument.

  12. Low energy ion-molecule reaction dynamics and chemiionization kinetics

    NASA Astrophysics Data System (ADS)

    Farrar, J. M.

    Low energy crossed ion beam neutral beam studies of a wide spectrum of elementary chemical reactions were performed. The reactive scattering work embodies crossed beam studies of simple chemical processes under single collision conditions which elucidate reaction dynamics by measuring product branching ratios, translational energy distributions and scattering angle distributions. The studies have emphasized the proton transfer reactions of the important flame cations HCO(+) and H3O(+) with a number of neutral molecules present in flames, including H2O, CH3OH, CH3CH2OH, and (CH3)2CO, and a wide variety of reactions of the ground state carbon cation, C(+)((2)P), with neutrals, illustrating the important reactions of insertion into C-H, O-H, N-H, and C-C bonds, as well as condensation reactions in which new C-C bonds are formed, yielding significant increases in the molecular weight of the charged product. These studies represent the first crossed beam studies in which information more detailed than rate constants and energy dependent total cross sections was inferred about the reaction dynamics.

  13. Effects of low-energy shock waves on oral bacteria.

    PubMed

    Novak, K F; Govindaswami, M; Ebersole, J L; Schaden, W; House, N; Novak, M J

    2008-10-01

    We have recently demonstrated that extracorporeal shock-wave therapy (ESWT) is effective in promoting the healing of dermal wounds and in regenerating alveolar bone lost through periodontal disease. The objective of the present study was to determine any antibacterial effect of ESWT on oral bacteria. Monoculture suspensions of 6 bacterial species were treated with 100 to 500 pulses of ESWT at energy flux densities (EFD) of 0.12 mJ/mm(2), 0.22 mJ/mm(2), and 0.3 mJ/mm(2). Following treatment, aliquots were plated for viability determination and compared with untreated controls. ESWT showed a significant microbicidal effect for Streptococcus mutans and an unencapsulated strain of Porphyromonas gingivalis following as few as 100 pulses at 0.3 mJ/mm(2) (p 0.05). These findings suggest that low-energy ESWT may be bactericidal for selected oral bacteria.

  14. Low-energy gamma ray attenuation characteristics of aviation fuels

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Shen, Chih-Ping; Sprinkle, Danny R.

    1990-01-01

    Am241 (59.5 keV) gamma ray attenuation characteristics were investigated in 270 aviation fuel (Jet A and Jet A-1) samples from 76 airports around the world as a part of world wide study to measure the variability of aviation fuel properties as a function of season and geographical origin. All measurements were made at room temperature which varied from 20 to 27 C. Fuel densities (rho) were measured concurrently with their linear attenuation coefficients (mu), thus providing a measure of mass attenuation coefficient (mu/rho) for the test samples. In 43 fuel samples, rho and mu values were measured at more than one room temperature, thus providing mu/rho values for them at several temperatures. The results were found to be independent of the temperature at which mu and rho values were measured. It is noted that whereas the individual mu and rho values vary considerably from airport to airport as well as season to season, the mu/rho values for all samples are constant at 0.1843 + or - 0.0013 cu cm/gm. This constancy of mu/rho value for aviation fuels is significant since a nuclear fuel quantity gauging system based on low energy gamma ray attenuation will be viable throughout the world.

  15. Low-Energy Elastic Electron Scattering by Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Zatsarinny O.; Bartschat, K.; Tayal, S. S.

    2006-01-01

    The B-spline R-matrix method is employed to investigate the low-energy elastic electron scattering by atomic oxygen. Flexible non-orthogonal sets of radial functions are used to construct the target description and to represent the scattering functions. A detailed investigation regarding the dependence of the predicted partial and total cross sections on the scattering model and the accuracy of the target description is presented. The predicted angle-integrated elastic cross sections are in good agreement with experiment, whereas significant discrepancies are found in the angle-differential elastic cross sections near the forward direction. .The near-threshold results are found to strongly depend on the treatment of inner-core short-range correlation effects in the target description, as well as on a proper account of the target polarizability. A sharp increase in the elastic cross sections below 1 eV found in some earlier calculations is judged to be an artifact of an unbalanced description of correlation in the N-electron target structure and the (N+l)-electron-collision problems.

  16. Maximum Likelihood Analysis of Low Energy CDMS II Germanium Data

    DOE PAGESBeta

    Agnese, R.

    2015-03-30

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from Pb210decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we also perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in ourmore » data. Finally, we confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.« less

  17. Inelastic pion scattering by /sup 13/C at low energies

    SciTech Connect

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  18. Photon strength and the low-energy enhancement

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Krtička, M.; Bleuel, D. L.; Allmond, J. M.; Basunia, M. S.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-08-01

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in 95Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to 95Mo photon strength function data measured at the University of Oslo.

  19. Photon strength and the low-energy enhancement

    SciTech Connect

    Wiedeking, M.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Hatarik, R.; Lesher, S. R.; Scielzo, N. D.; Krtička, M.; Allmond, J. M.; Basunia, M. S.; Fallon, P.; Firestone, R. B.; Lake, P. T.; Lee, I-Y.; Paschalis, S.; Petri, M.; Phair, L.; Goldblum, B. L.

    2014-08-14

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in {sup 95}Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to {sup 95}Mo photon strength function data measured at the University of Oslo.

  20. Seeking to Improve Low Energy Neutral Atom Detection in Space

    NASA Technical Reports Server (NTRS)

    Shappirio, M.; Coplan, M.; Chornay, D.; Collier, M.; Herrero, F.; Ogilvie, K.; Williams, E.

    2007-01-01

    The detection of energetic neutral atoms allows for the remote examination of the interactions between plasmas and neutral populations in space. Before these neutral atoms can be measured, they must first be converted to ions. For the low energy end of this spectrum, interaction with a conversion surface is often the most efficient method to convert neutrals into ions. It is generally thought that the most efficient surfaces are low work functions materials. However, by their very nature, these surfaces are highly reactive and unstable, and therefore are not suitable for space missions where conditions cannot be controlled as they are in a laboratory. We therefore are looking to optimize a stable surface for conversion efficiency. Conversion efficiency can be increased either by changing the incident angle of the neutral particles to be grazing incidence and using stable surfaces with high conversion efficiencies. We have examined how to increase the angle of incidence from -80 degrees to -89 degrees, while maintaining or improving the total active conversion surface area without increasing the overall volume of the instrument. We are developing a method to micro-machine silicon, which will reduce the volume to surface area ratio by a factor of 60. We have also examined the material properties that affect the conversion efficiency of the surface for stable surfaces. Some of the parameters we have examined are work function, smoothness, and bond structure. We find that for stable surfaces, the most important property is the smoothness of the surface.

  1. Analysis of latency performance of bluetooth low energy (BLE) networks.

    PubMed

    Cho, Keuchul; Park, Woojin; Hong, Moonki; Park, Gisu; Cho, Wooseong; Seo, Jihoon; Han, Kijun

    2014-12-23

    Bluetooth Low Energy (BLE) is a short-range wireless communication technology aiming at low-cost and low-power communication. The performance evaluation of classical Bluetooth device discovery have been intensively studied using analytical modeling and simulative methods, but these techniques are not applicable to BLE, since BLE has a fundamental change in the design of the discovery mechanism, including the usage of three advertising channels. Recently, there several works have analyzed the topic of BLE device discovery, but these studies are still far from thorough. It is thus necessary to develop a new, accurate model for the BLE discovery process. In particular, the wide range settings of the parameters introduce lots of potential for BLE devices to customize their discovery performance. This motivates our study of modeling the BLE discovery process and performing intensive simulation. This paper is focused on building an analytical model to investigate the discovery probability, as well as the expected discovery latency, which are then validated via extensive experiments. Our analysis considers both continuous and discontinuous scanning modes. We analyze the sensitivity of these performance metrics to parameter settings to quantitatively examine to what extent parameters influence the performance metric of the discovery processes.

  2. Collisions of low-energy electrons with cyclohexane

    SciTech Connect

    Barbosa, Alessandra Souza; Bettega, Márcio H. F.

    2014-12-28

    We report calculated cross sections for elastic scattering of low-energy electrons by cyclohexane (c-C{sub 6}H{sub 12}). We employed the Schwinger multichannel method implemented with norm-conserving pseudopotentials in the static-exchange and static-exchange plus polarization approximations, for impact energies up to 30 eV. We compare our calculated integral cross section with experimental total cross sections available in the literature. We also compare our calculated differential cross sections (DCSs) with experimental results for benzene and experimental and theoretical results for 1,4-dioxane, in order to investigate the similarities between those molecules under electron collisions. Although benzene is a cyclic six-carbon molecule, as cyclohexane, we found that the differential cross sections of the latter are more similar to those of 1,4-dioxane than those of benzene. These similarities suggest that the geometry may play an important role in the behavior of the DCSs of these molecules. Our integral cross section displays a broad structure at around 8.5 eV, in agreement with the total cross section experimental data of 8 eV and vibrational excitation data of 7.5 eV. The present integral cross section also shows the presence of a Ramsauer-Townsend minimum at around 0.12 eV. In general, our integral cross section shows a qualitative agreement with the experimental total cross section.

  3. Review of lattice results concerning low-energy particle physics

    DOE PAGESBeta

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; et al

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination ofmore » the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.« less

  4. Low-energy theory of transport in Majorana wire junctions

    NASA Astrophysics Data System (ADS)

    Zazunov, A.; Egger, R.; Levy Yeyati, A.

    2016-07-01

    We formulate and apply a low-energy transport theory for hybrid quantum devices containing junctions of topological superconductor (TS) wires and conventional normal (N) or superconducting (S) leads. We model TS wires as spinless p -wave superconductors and derive their boundary Keldysh Green's function, capturing both the Majorana end state and continuum quasiparticle excitations in a unified manner. We also specify this Green's function for a finite-length TS wire. Junctions connecting different parts of the device are described by the standard tunneling Hamiltonian. Using this Hamiltonian approach, one also has the option to include many-body interactions in a systematic manner. For N-TS junctions, we provide the current-voltage (I -V ) characteristics at arbitrary junction transparency and give exact results for the shot-noise power and the excess current. For TS-TS junctions, analytical results for the thermal noise spectrum and for the I -V curve in the high-transparency low-bias regime are presented. For S-TS junctions, we compute the entire I -V curve and clarify the conditions for having a finite Josephson current.

  5. Low energy, high power hydrogen neutral beam for plasma heating.

    PubMed

    Deichuli, P; Davydenko, V; Ivanov, A; Korepanov, S; Mishagin, V; Smirnov, A; Sorokin, A; Stupishin, N

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  6. Sparse + low-energy decomposition for viscous conservation laws

    NASA Astrophysics Data System (ADS)

    Hou, Thomas Y.; Li, Qin; Schaeffer, Hayden

    2015-05-01

    For viscous conservation laws, solutions contain smooth but high-contrast features, which require the use of fine grids to properly resolve. On coarse grids, these high-contrast jumps resemble shocks rather than their true viscous profiles, which could lead to issues in the numerical approximation of their underlying dynamics. In many cases, the equations of motion emit traveling wave solutions which can be used to represent the viscous profiles analytically. The traveling wave solutions can be thought of as a lower dimensional representation of the motion, since they contain information from the evolution equation, but are constant along certain time-space curves. Using a parameterized basis involving the traveling waves, along with the sparse + low-energy decompositions found in imaging sciences, we propose an approximation to viscous conservation laws which separates the coarse smooth component from the sharp fine one. Our method provides an appropriate approximation to the solution on a coarse grid, thereby accurately under-resolving the viscous profile. This is similar to the philosophy of shock capturing methods, in the sense that we want to capture the viscous front without needing to resolve the profile. Theoretical results on the consistency of our method are shown in general. We provide several computational examples for convex and non-convex fluxes.

  7. Low energy, high power hydrogen neutral beam for plasma heating

    NASA Astrophysics Data System (ADS)

    Deichuli, P.; Davydenko, V.; Ivanov, A.; Korepanov, S.; Mishagin, V.; Smirnov, A.; Sorokin, A.; Stupishin, N.

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  8. Ultra-low-energy analog straintronics using multiferroic composites

    NASA Astrophysics Data System (ADS)

    Roy, Kuntal

    2014-03-01

    Multiferroic devices, i.e., a magnetostrictive nanomagnet strain-coupled with a piezoelectric layer, are promising as binary switches for ultra-low-energy digital computing in beyond Moore's law era [Roy, K. Appl. Phys. Lett. 103, 173110 (2013), Roy, K. et al. Appl. Phys. Lett. 99, 063108 (2011), Phys. Rev. B 83, 224412 (2011), Scientific Reports (Nature Publishing Group) 3, 3038 (2013), J. Appl. Phys. 112, 023914 (2012)]. We show here that such multiferroic devices, apart from performing digital computation, can be also utilized for analog computing purposes, e.g., voltage amplification, filter etc. The analog computing capability is conceived by considering that magnetization's mean orientation shifts gradually although nanomagnet's potential minima changes abruptly. Using tunneling magnetoresistance (TMR) measurement, a continuous output voltage while varying the input voltage can be produced. Stochastic Landau-Lifshitz-Gilbert (LLG) equation in the presence of room-temperature (300 K) thermal fluctuations is solved to demonstrate the analog computing capability of such multiferroic devices. This work was supported in part by FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

  9. Biophysics behavior of acupuncture points irradiated with low energy lasers.

    PubMed

    Moldovan, C

    2007-01-01

    This work describes the Low Energy Laser (LEL) coherent light interaction with the skin cover on acupuncture loci for the purpose of detecting and measuring the spatial and temporal alteration of the thermal, electric and optical properties of the LI4 (HEGU) acupoint, irradiated with a 685 nm, 30 mW, III.B Laser. Novel electrostatic imaging technique, an original Acupuncture 3-D Thermal and Electric Mapping Technique and an original Method for Laser-Skin Reflectance, were used in the study. The results indicate that the visible laser light, with low frequency and low power, specifically modify the 3-D pattern of the temperature, electric potential and electric impedance outline of an acupuncture point, meanwhile with a significant decrease of the laser reflectance index, all measured on a 27 apparently healthy subject lot (48 years mean age, 54% male), when comparing with a non-active, non-acupunctural skin area, placed on the volar side of the same hand. The biophysical method presented, combines in a complex way and reproducible the electro stasis exploration (bioelectric homeostasis), with cutaneous thermodynamic exploration and photo-optical exploration of the derma and provides information that can be appreciated in dynamics and compared depending on the exploration target.

  10. Review of lattice results concerning low-energy particle physics

    SciTech Connect

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; Jüttner, A.; Kaneko, T.; Laiho, J.; Lellouch, L.; Leutwyler, H.; Lubicz, V.; Lunghi, E.; Necco, S.; Onogi, T.; Pena, C.; Sachrajda, C. T.; Sharpe, S. R.; Simula, S.; Sommer, R.; Van de Water, R. S.; Vladikas, A.; Wenger, U.; Wittig, H.

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination of the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.

  11. Projectile - Mass asymmetry systematics for low energy incomplete fusion

    NASA Astrophysics Data System (ADS)

    Singh, Pushpendra P.; Yadav, Abhishek; Sharma, Vijay R.; Sharma, Manoj K.; Kumar, Pawan; Sahoo, Rudra N.; Kumar, R.; Singh, R. P.; Muralithar, S.; Singh, B. P.; Bhowmik, R. K.; Prasad, R.

    2015-06-01

    In the present work, low energy incomplete fusion (ICF) in which only a part of projectile fuses with target nucleus has been investigated in terms of various entrance channel parameters. The ICF strength function has been extracted from the analysis of experimental excitation functions (EFs) measured for different projectile-target combinations from near- to well above- barrier energies in 12C,16O(from 1.02Vb to 1.64Vb)+169Tm systems. Experimental EFs have been analysed in the framework statistical model code PACE4 based on the idea of equilibrated compound nucleus decay. It has been found that the value of ICF fraction (FICF) increases with incident projectile energy. A substantial fraction of ICF (FICF ≈ 7 %) has been accounted even at energy as low as ≈ 7.5% above the barrier (at relative velocity νrel ≈0.027) in 12C+169Tm system, and FICF ≈ 10 % at νrel ≈0.014 in 16O+169Tm system. The probability of ICF is discussed in light of the Morgenstern's mass-asymmetry systematics. The value of FICF for 16O+169Tm systems is found to be 18.3 % higher than that observed for 12C+169Tm systems. Present results together with the re-analysis of existing data for nearby systems conclusively demonstrate strong competition of ICF with CF even at slightly above barrier energies, and strong projectile dependence that seems to supplement the Morgenstern's systematics.

  12. MOS Circuitry Would Detect Low-Energy Charged Particles

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva; Wadsworth, Mark

    2003-01-01

    Metal oxide semiconductor (MOS) circuits for measuring spatially varying intensities of beams of low-energy charged particles have been developed. These circuits are intended especially for use in measuring fluxes of ions with spatial resolution along the focal planes of mass spectrometers. Unlike prior mass spectrometer focal-plane detectors, these MOS circuits would not be based on ion-induced generation of electrons, and photons; instead, they would be based on direct detection of the electric charges of the ions. Hence, there would be no need for microchannel plates (for ion-to-electron conversion), phosphors (for electron-to-photon conversion), and photodetectors (for final detection) -- components that degrade spatial resolution and contribute to complexity and size. The developmental circuits are based on linear arrays of charge-coupled devices (CCDs) with associated readout circuitry (see figure). They resemble linear CCD photodetector arrays, except that instead of a photodetector, each pixel contains a capacitive charge sensor. The capacitor in each sensor comprises two electrodes (typically made of aluminum) separated by a layer of insulating material. The exposed electrode captures ions and accumulates their electric charges during signal-integration periods.

  13. Structural surface investigations with low-energy backscattered electrons

    NASA Astrophysics Data System (ADS)

    De Crescenzi, Maurizio

    The development of electron spectroscopies based on inelastic scattering fine structure is driven mainly by the need for structural methods which allow the investigation of the geometrical environment of different atomic species of the surface region of the sample. The EELFS (Extended Energy Loss Fine Structure) technique, using low-kinetic-energy electrons (1000-2000 eV) in reflection geometry, has been proven a useful tool for local structural investigation of clean surfaces, thin films and chemisorbed species. The main appeal of this technique, besides its experimental accessibility, is that the data analysis follows the procedure used for EXAFS (Extended X-ray Absorption Fine Structure) spectroscopy to obtain the atomic selectivity, the radial distribution function, the coordination number and the thermal and anisotropic effects. The near-edge energy-loss feature has been used to investigate the density of empty states close to EF and it appeeal particularly sensitive for following the structural changes and for discriminating among various phases and compound formations which occur in the surface region. In this work I review some recent developments, applications and theoretical considerations of the EELFS technique to give local structural parameters and to assess the basic mechanisms which dominate the low-energy electron-surface interaction.

  14. Selection rules in low energy string effective lagrangians

    NASA Astrophysics Data System (ADS)

    Dolan, L.; Lau, S.

    1992-01-01

    Selection rules which restrict elementary particle interactions are derived as the low-energy limit of superstring theory. A general mechanism is demonstrated, in four-dimensional string tree-amplitudes, whereby the supersymmetric trilinear Yukawa-like couplings in the effective lagrangian which violate lepton number vanish, terms which otherwise occur naturally in supersymmetric versions of the standard model. Explicit expressions for the vertex operators, and all cubic bosonic couplings involving the Yang-Mills gauge bosons and the graviton, together with the scalar and anti-symmetric tensor components of gravity are given. There are no √2 α' corrections to the three-point string tree-amplitudes, a result which eliminates any higher derivative trilinear couplings among these fields in the effective action. In this four-dimensional string theory, expressions are derived for the gravitational coupling constant κ and the Yang-Mills coupling constant gYM in terms of the two string parameters: the universal Regge slope parameter which is the origin of the length scale √2 α', and the dimensionless string coupling constant g. We find κ = {1}/{2}g√2α' and g YM = g .

  15. Low energy electrons and swift ion track structure in PADC

    SciTech Connect

    Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.; Champion, Christophe

    2015-05-27

    The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particular incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.

  16. Mutual neutralization in low-energy H+ +F- collisions

    NASA Astrophysics Data System (ADS)

    Mezei, J. Zs.; Roos, J. B.; Shilyaeva, K.; Elander, N.; Larson, Å.

    2011-07-01

    The cross section for mutual neutralization in collisions between H+ and F- ions at low energies (E⩽10 eV) is calculated using a molecular close-coupling approach. Two different representations of the quasidiabatic potentials and couplings of HF are used. The effect of autoionization on the cross section is investigated. The coupled Schrödinger equation for the nuclear motion is solved using a numerical integration of the corresponding matrix Riccati equation and the cross section for mutual neutralization is computed from the asymptotic value of the logarithmic derivative of the radial wave function. The magnitude of the cross section for mutual neutralization in this reaction is small compared to other systems. This can be understood by the lack of avoided crossings at large internuclear distances. Resonant structures are found in the cross section and these are assigned with dominant angular momentum quantum number. The cross section for mutual neutralization in collisions of D+ and F- ions is also calculated.

  17. Low-energy fusion caused by an interference

    NASA Astrophysics Data System (ADS)

    Ivlev, B.

    2013-03-01

    Fusion of two deuterons at room-temperature energy is studied. The nuclei are in vacuum with no connection to any external source (electric or magnetic field, illumination, surrounding matter, traps, etc.) which may accelerate them. The energy of the two nuclei is conserved and remains small during the motion through the Coulomb barrier. The penetration through this barrier, which is the main obstacle for low-energy fusion, strongly depends on a form of the incident flux on the Coulomb center at large distances from it. In contrast to the usual scattering, the incident wave is not a single plane wave but the certain superposition of plane waves of the same energy and various directions; for example, a convergent conical wave. As a result of interference, the wave function close to the Coulomb center is determined by a cusp caustic which is probed by de Broglie waves. The particle flux gets away from the cusp and moves to the Coulomb center providing a not negligible probability of fusion (cusp driven tunneling). Getting away from a caustic cusp also occurs in optics and acoustics.

  18. Ion implantation effects in 'cosmic' dust grains

    NASA Technical Reports Server (NTRS)

    Bibring, J. P.; Langevin, Y.; Maurette, M.; Meunier, R.; Jouffrey, B.; Jouret, C.

    1974-01-01

    Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering.

  19. Mass and energy deposition effects of implanted ions on solid sodium formate

    NASA Astrophysics Data System (ADS)

    Wang, Xiangqin; Shao, Chunlin; Yao, Jianming; Yu, Zengliang

    2000-07-01

    Solid sodium formate was implanted by low energy N +, H +, and Ar + ions. Measured with electron paramagnetic resonance (EPR) and Fourier-transform infrared (FT-IR), it was observed that new CH 2, CH 3 groups and COO - radical ion were produced in the implanted sodium formate. Analyzing with the highly sensitive ninhydrin reaction, it was found that a new NH 2 functional group was formed upon N + ion implantation, and its yield increased along with implantation dose but decreased with the ion's energy.

  20. Low-energy Charged Particle Measurements in the Heliosheath

    NASA Astrophysics Data System (ADS)

    Decker, R. B.

    2011-12-01

    This talk will focus on recent measurements from the LECP instruments on Voyager 1 and Voyager 2. Voyager 1 (118 AU, N34 deg.) crossed the termination shock at 94.0 AU in Dec. 2004 and is roughly 24 AU into the inner heliosheath. Voyager 2 (96 AU, S30 deg) crossed the shock at 83.5 AU in Sep. 2007 and is roughly 13 AU into the heliosheath. Large variations in the intensities, energy spectra, and angular distributions of low-energy heliosheath ions and electrons have occurred during the past year, evidently in response to an increase in the number of solar active regions in January 2010. For example, starting around 2010.8, ion intensities at Voyager 1 began a two-step exponential decrease. The intensities of ions below 0.5 MeV fell by 40%, reaching minima around 2011.5 that were the lowest measured since mid-2005. During the intensity drop at Voyager 1 the ion energy spectrum evolved to a single power-law with an index -1.5. Similar intensity drops began somewhat earlier at Voyager 2, and the intensity minima of the low-energy ions occurred on 2011.2, one-third of a year earlier than at Voyager 1. In addition, after the ion intensities had recovered at Voyager 2, they were deficient at lower energies compared to the pre-drop levels, causing the energy spectrum to flatten with decreasing energy. During the intensity drop at Voyager 2, ion angular distributions evolved from convective-like, consistent with the measured plasma flow velocity, to azimuthal, more consistent with unidirectional streaming along the mean magnetic field. We will also summarize the heliosheath plasma flow velocity in the R-T (instrument scan) plane that is estimated using angular data from the three lowest energy Voyager 1 LECP ion channels, which cover 40-139 keV. The estimated radial component of flow decreased from about 60 km/s to about 0 km/s at a rate of -19 km/s/yr during 2008.7-2010.3, was consistent with 0 km/s from 2010.3-2011.0, and then went negative, averaging about -13 km