WorldWideScience

Sample records for advanced thin ionization

  1. Ionization Modeling Astrophysical Gaseous Structures. I. The Optically Thin Regime

    CERN Document Server

    Churchill, Christopher W; Medina, Amber; Vliet, Jacob R Vander

    2014-01-01

    We present a code for modelling the ionization conditions of optically thin astrophysical gas structures. Given the gas hydrogen density, equilibrium temperature, elemental abundances, and the ionizing spectrum, the code solves the equilibrium ionization fractions and number densities for all ions from hydrogen to zinc. The included processes are photoionization, Auger ionization, direct collisional ionization, excitation auto-ionization, charge exchange ionization, two-body radiative recombination, dielectronic recombination, and charge exchange recombination. The ionizing spectrum can be generalized to include the ultraviolet background (UVB) and/or Starburst99 stellar populations of various masses, ages, metallicities, and distances. The ultimate goal with the code is to provide fast computation of the ionization conditions of gas in N-body + hydrodynamics cosmological simulations, in particular adaptive mesh refinement codes, in order to facilitate absorption line analysis of the simulated gas for compari...

  2. Reactive ionized physical vapor deposition of thin films

    OpenAIRE

    Konstantinidis, S.; Snyders, R.

    2011-01-01

    Abstract In this article, the experimental results obtained in our laboratory for the last 10 years and related to the reactive Ionized Physical Vapor Deposition (IPVD) processes are reviewed. Titanium oxide and titanium nitride thin films were chosen as case studies. The titanium-based thin films were synthesized from a pure titanium target sputtered in a mixture of argon and reactive gas (oxygen or nitrogen). Two IPVD processes were investigated namely (i) reactive magnetron sput...

  3. Thin films deposited by laser ablation for the measurement of the ionizing and non-ionizing radiation

    International Nuclear Information System (INIS)

    In this work the obtained results to synthesize thin films of amorphous carbon with incorporated nitrogen and hydrogen are presented, as well as thin films of aluminium oxide using the laser ablation technique. The thin films were exposed to ionizing radiation (gamma rays of a 60 Co source, beta radiation of a 90 Sr source) and a non-ionizing radiation (UV radiation). The obtained results show that it is possible to obtain materials in thin film form with thickness of hundreds of nanometers, which present thermoluminescent response when being irradiated with ionizing radiation and non-ionizing radiation. (Author)

  4. Research on Advanced Thin Film Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, Ronald B. [Tufts Univ., Medford, MA (United States)

    2003-11-24

    During the past 7 years, the Tufts group has been carrying out research on advanced thin film batteries composed of a thin film LiCo02 cathode (positive electrode), a thin film LiPON (lithium phosphorous oxynitride) solid electrolyte, and a thin film graphitic carbon anode (negative electrode), under grant DE FG02-95ER14578. Prior to 1997, the research had been using an rfsputter deposition process for LiCoOi and LiPON and an electron beam evaporation or a controlled anode arc evaporation method for depositing the carbon layer. The pre-1997 work led to the deposition of a single layer cell that was successfully cycled for more than 400 times [1,2] and the research also led to the deposition of a monolithic double-cell 7 volt battery that was cycled for more than 15 times [3]. Since 1997, the research has been concerned primarily with developing a research-worthy and, possibly, a production-worthy, thin film deposition process, termed IBAD (ion beam assisted deposition) for depositing each ofthe electrodes and the electrolyte of a completely inorganic solid thin film battery. The main focus has been on depositing three materials - graphitic carbon as the negative electrode (anode), lithium cobalt oxide (nominally LiCoCb) as the positive electrode (cathode), and lithium phosphorus oxynitride (LiPON) as the electrolyte. Since 1998, carbon, LiCoOa, and LiPON films have been deposited using the IBAD process with the following results.

  5. Physics of thin films advances in research and development

    CERN Document Server

    Hass, Georg; Vossen, John L

    2013-01-01

    Physics of Thin Films: Advances in Research and Development, Volume 12 reviews advances that have been made in research and development concerning the physics of thin films. This volume covers a wide range of preparative approaches, physics phenomena, and applications related to thin films. This book is comprised of four chapters and begins with a discussion on metal coatings and protective layers for front surface mirrors used at various angles of incidence from the ultraviolet to the far infrared. Thin-film materials and deposition conditions suitable for minimizing reflectance changes with

  6. The electrical transport properties of thin metal films containing ionized impurities

    International Nuclear Information System (INIS)

    Analytical expression for the electrical conductivity and thermoelectric power are calculated for thin metal films containing ionized impurities that affect the value and the energy dependance of the electron relaxation time. The electrical conductivity decreases, whereas the thermoelectric power increases on addition of such impurities. For pure lattice scattering there is no size effect in the thermoelectric power

  7. Advances in CZTS thin films and nanostructured

    Science.gov (United States)

    Ali, N.; Ahmed, R.; Bakhtiar-Ul-Haq; Shaari, A.

    2015-06-01

    Already published data for the optical band gap (Eg) of thin films and nanostructured copper zinc tin sulphide (CZTS) have been reviewed and combined. The vacuum (physical) and non-vacuum (chemical) processes are focused in the study for band gap comparison. The results are accumulated for thin films and nanostructured in different tables. It is inferred from the re- view that the nanostructured material has plenty of worth by engineering the band gap for capturing the maximum photons from solar spectrum.

  8. Thin film characterisation by advanced X-ray diffraction techniques

    International Nuclear Information System (INIS)

    The Fifth School on X-ray diffraction from polycrystalline materials was devoted to thin film characterization by advanced X-ray diffraction techniques. Twenty contributions are contained in this volume; all twenty are recorded in the INIS Database. X-ray diffraction is known to be a powerful analytical tool for characterizing materials and understanding their structural features. The aim of these articles is to illustrate the fundamental contribution of modern diffraction techniques (grazing incidence, surface analysis, standing waves, etc.) to the characterization of thin and ultra-thin films, which have become important in many advanced technologies

  9. Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

    Energy Technology Data Exchange (ETDEWEB)

    Jay R. Johnson and Hideo Okuda

    2008-05-20

    Nearly half of the time, auroral displays exhibit thin, bright layers known as \\enhanced aurora." There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

  10. Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

    International Nuclear Information System (INIS)

    Nearly half of the time, auroral displays exhibit thin, bright layers known as 'enhanced aurora'. There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

  11. Advances in thin-film solar cells

    CERN Document Server

    Dharmadasa, I M

    2012-01-01

    This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines

  12. Radiation effects in advanced SOI devices: New insights into total ionizing dose and single-event effects

    International Nuclear Information System (INIS)

    The SOI technology has already demonstrated intrinsic resistance to transient radiation effects due to the dielectric isolation provided by the buried oxide. But this special feature raises questions about their Total Ionizing Dose (TID) sensitivity, particularly in Fully Depleted (FD) SOI and multiple gate devices. This paper thus gives an overview of recent advances in radiation effects on innovative SOI devices. Both TID and Single-Event Effects (SEE) in Extra Thin SOI (ETSOI) and FinFET devices are reviewed as well as upcoming challenges to mitigate radiation effects in nanometer scale SOI technologies. (authors)

  13. Recent technological advances in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H.S.; Zwelbel, K.; Surek, T.

    1990-03-01

    High-efficiency, low-cost thin film solar cells are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. This paper reviews the substantial advances made by several thin film solar cell technologies, namely, amorphous silicon, copper indium diselenide, cadmium telluride, and polycrystalline silicon. Recent examples of utility demonstration projects of these emerging materials are also discussed. 8 refs., 4 figs.

  14. Preface: Advanced Thin Film Developments and Nano Structures

    Institute of Scientific and Technical Information of China (English)

    Ray Y.Lin

    2005-01-01

    @@ In this special issue, we invited a few leading materials researchers to present topics in thin films, coatings, and nano structures. Readers will find most recent developments in topics, including recent advances in hard, tough, and low friction nanocomposite coatings; thin films for coating nanomaterials; electroless plating of silver thin films on porous Al2O3 substrate; CrN/Nano Cr interlayer coatings; nano-structured carbide derived carbon (CDC) films and their tribology; predicting interdiffusion in high-temperature coatings; gallium-catalyzed silica nanowire growth; and corrosion protection properties of organofunctional silanes. Authors are from both national laboratories and academia.

  15. Advanced quantification of plutonium ionization potential to support nuclear forensic evaluations by resonance ionization mass spectrometry

    OpenAIRE

    Lensegrav, Craig T.

    2015-01-01

    Approved for public release; distribution is unlimited Ongoing work seeks to apply the technology of resonance ionization mass spectrometry (RIMS) to problems related to nuclear forensics and, in particular, to the analysis and quantification of the debris from nuclear detonations. As part of this effort, modeling and simulation methods are being applied to analyze and predict the potential for ionization by laser excitation of isotopes of both uranium and plutonium. Early work focused on ...

  16. Advances in small intestinal ionizing radiation injury research

    International Nuclear Information System (INIS)

    Intestinal ionising radiation injuries are a dose limiting factor in the course of radiotherapy of abdominal and pelvic malignancies. In this paper it is reviewed that ionizing radiation injuries of small intestine,including clinical symptoms, epithelium and submucosa changes, signal molecular expression changes, histological and ultrastructure changes. The ongoing works of our laboratory on subjects of intestinal injuries induced by heavy ions and protection against these injuries are also presented. (authors)

  17. Relation between molecule ionization energy, film thickness and morphology of two indandione derivatives thin films

    Science.gov (United States)

    Grzibovskis, Raitis; Vembris, Aivars; Pudzs, Kaspars

    2016-08-01

    Nowadays most organic devices consist of thin (below 100 nm) layers. Information about the morphology and energy levels of thin films at such thickness is essential for the high efficiency devices. In this work we have investigated thin films of 2-(4-[N,N-dimethylamino]-benzylidene)-indene-1,3-dione (DMABI) and 2-(4-(bis(2-(trityloxy)ethyl)amino)benzylidene)-2H-indene-1,3-dione (DMABI-6Ph). DMABI-6Ph is the same DMABI molecule with attached bulky groups which assist formation of amorphous films from solutions. Polycrystalline structure was obtained for the DMABI thin films prepared by thermal evaporation in vacuum and amorphous structure for the DMABI-6Ph films prepared by spin-coating method. Images taken by SEM showed separate crystals or islands at the thickness of the samples below 100 nm. The ionization energy of the studied compounds was determined using photoemission yield spectroscopy. A vacuum level shift of 0.40 eV was observed when ITO electrode was covered with the thin film of the organic compound. Despite of the same active part of the investigated molecules the ITO/DMABI interface is blocking electrons while ITO/DMABI-6Ph interface is blocking holes.

  18. Thin films deposited by laser ablation for the measurement of the ionizing and non-ionizing radiation; Peliculas delgadas depositadas por ablacion laser para la medicion de radiacion ionizante y no ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Villarreal B, J.E.; Escobar A, L.; Camps, E.; Romero, S.; Gonzalez, P.; Salinas, B. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2001-07-01

    In this work the obtained results to synthesize thin films of amorphous carbon with incorporated nitrogen and hydrogen are presented, as well as thin films of aluminium oxide using the laser ablation technique. The thin films were exposed to ionizing radiation (gamma rays of a {sup 60} Co source, beta radiation of a {sup 90} Sr source) and a non-ionizing radiation (UV radiation). The obtained results show that it is possible to obtain materials in thin film form with thickness of hundreds of nanometers, which present thermoluminescent response when being irradiated with ionizing radiation and non-ionizing radiation. (Author)

  19. Electronic properties of ion implanted crystalline polymer thin film deposited by ionized cluster beam

    International Nuclear Information System (INIS)

    Polyethylene thin film deposited by the ionized cluster beam deposition technique shows preferential crystal orientation at optimum deposit condition, and the lattice parameters of the crystalline PE film are in good agreement with those of the single crystal PE. The crystalline PE film reveals that the number of side chains is reduced. The conductivity of Li+, Na+ and K+ implanted crystalline PE films has a close correlation with defects generated by ion irradiation, and the conduction mechanism turns out to be the one-dimensional hopping conduction. (orig.)

  20. Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers

    Directory of Open Access Journals (Sweden)

    Q. H. Zhou

    2004-02-01

    Full Text Available The aspect sensitivity of VHF echoes from field aligned irregularities (FAI within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (perpendicular to B, substantial power can be obtained off the perpendicular to B direction if the ionization trail/layer is thin. When the FAI length is 20 m, the power observed 6° off perpendicular to B is about 10 db below that perpendicular to the B direction. Meteoric FAI echoes can potentially be used to determine the diffusion rate in the mesopause region. Based on the aspect sensitivity analysis, we conclude that the range spread trail echoes far off perpendicular to B observed by powerful VHF radars are likely due to overdense meteors. Our simulation also shows that ionospheric FAI echoes can have an altitude smearing effect of about 4 km if the vertical extension of a FAI layer is around 100 m, which has often been observed at Arecibo. The altitude smearing effect can account for the fact that the Es layers observed by the Arecibo incoherent scatter radar are typically much narrower than FAI layers and the occurrence of double spectral peaks around the Es layer altitude in FAI echoes.

  1. Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers

    Directory of Open Access Journals (Sweden)

    Q. H. Zhou

    2004-01-01

    Full Text Available The aspect sensitivity of VHF echoes from field aligned irregularities (FAI within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (B, substantial power can be obtained off the B direction if the ionization trail/layer is thin. When the FAI length along B is 20 m, the power observed 6° off B is about 10 db below that perpendicular to the B direction. Meteoric FAI echoes can potentially be used to determine the diffusion rate in the mesopause region. Based on the aspect sensitivity analysis, we conclude that the range spread trail echoes far off B observed by powerful VHF radars are likely due to overdense meteors. Our simulation also shows that ionospheric FAI echoes can have an altitude smearing effect of about 4 km if the vertical extension of a FAI-layer is around 100 m, which has often been observed at Arecibo. The altitude smearing effect can account for the fact that the Es-layers observed by the Arecibo incoherent scatter radar are typically much narrower than FAI-layers and the occurrence of double spectral peaks around the Es-layer altitude in FAI echoes.

  2. Development of thin gaseous ionization detectors for measurements of high-energy hadron beams

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyong Sei; Hong, Byung Sik; Lee, Ki Soo; Park, Sung Keun; Yu, Jae Hee [Korea University, Seoul (Korea, Republic of); Kim, Sang Yeol [NoticeKorea, Anyang (Korea, Republic of)

    2014-04-15

    Thin gaseous ionization detectors have been developed based on a current-integration mode for measurements of high-energy hadron beams. In the present detector R and D, two different types of prototype detectors with an active area of 16 x 16 cm{sup 2}, each equipped with 256-signal processing channels, were manufactured and tested with 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The first one was equipped with a single gas electron multiplier (GEM), and the second one was a thin-plane ionization detector without the GEM foil loaded. The linearities of the detector responses for both detectors were examined for various proton-beam intensities. The quantitative accuracies for the channel-response data and for the total detector responses measured for 43-MeV protons were 0.4% and 0.34%, respectively. We conclude from the beam test that operating both types of detectors in the current-integration mode will allow quality measurements of dynamic-mode hadron beams to be performed with accuracies of better than 1%.

  3. Adsorption of Emerging Ionizable Contaminants on Carbon Nanotubes: Advancements and Challenges.

    Science.gov (United States)

    Ma, Xingmao; Agarwal, Sarang

    2016-01-01

    The superior adsorption capacity of carbon nanotubes has been well recognized and there is a wealth of information in the literature concerning the adsorption of unionized organic pollutants on carbon nanotubes. Recently, the adsorption of emerging environmental pollutants, most of which are ionizable, has attracted increasing attention due to the heightened concerns about the accumulation of these emerging contaminants in the environment. These recent studies suggest that the adsorption of emerging ionizable contaminants on carbon nanotubes exhibit different characteristics than unionized ones. For example, a new charge-assisted intermolecular force has been proposed for ionizable compounds because some adsorption phenomenon cannot be easily explained by the conventional force theory. The adsorption of ionizable compounds also displayed much stronger dependence on solution pH and ionic strength than unionized compounds. This article aims to present a brief review on the current understanding of the adsorption of emerging ionizable contaminants to carbon nanotubes and discuss further research needs required to advance the mechanistic understanding of the interactions between ionizable contaminants and carbon nanotubes. PMID:27187338

  4. Adsorption of Emerging Ionizable Contaminants on Carbon Nanotubes: Advancements and Challenges

    Directory of Open Access Journals (Sweden)

    Xingmao Ma

    2016-05-01

    Full Text Available The superior adsorption capacity of carbon nanotubes has been well recognized and there is a wealth of information in the literature concerning the adsorption of unionized organic pollutants on carbon nanotubes. Recently, the adsorption of emerging environmental pollutants, most of which are ionizable, has attracted increasing attention due to the heightened concerns about the accumulation of these emerging contaminants in the environment. These recent studies suggest that the adsorption of emerging ionizable contaminants on carbon nanotubes exhibit different characteristics than unionized ones. For example, a new charge-assisted intermolecular force has been proposed for ionizable compounds because some adsorption phenomenon cannot be easily explained by the conventional force theory. The adsorption of ionizable compounds also displayed much stronger dependence on solution pH and ionic strength than unionized compounds. This article aims to present a brief review on the current understanding of the adsorption of emerging ionizable contaminants to carbon nanotubes and discuss further research needs required to advance the mechanistic understanding of the interactions between ionizable contaminants and carbon nanotubes.

  5. Thin-layer chromatography with flame ionization detection in the characterization of pitches

    Energy Technology Data Exchange (ETDEWEB)

    Cebolla, V.L.; Membrado, L.; Vela, J. [Instituto de Carboquimica, Zaragoza (Spain)] [and others

    1995-12-31

    TLC-FID is a rapid, quality-control oriented technique which joins the advantages of Thin-Layer (TLC) with the possibility of quantification of the separated peaks using a Flame Ionization Detector (FID). In the case of heavy fossil fuels, group-type analysis can be achieved with the possibility of a direct quantification of heavy/polar groups, without any preseparation, and in short analysis times with regard to the current techniques. However, although TLC-FID has been used since the eighties in many fields of Chemistry, results were demonstrated to depend on the technique (analytical system plus methodology) used. This work intends to analyze the fundamental parameters involved in TLC-FID technique using adequate technology and methodology, and to lay the groundwork for a correct group-type characterization of pitches.

  6. Investigation of thin ZnO layers in view of laser desorption-ionization

    Science.gov (United States)

    Grechnikov, A. A.; Georgieva, V. B.; Alimpiev, S. S.; Borodkov, A. S.; Nikiforov, S. M.; Simanovsky, Ya O.; Dimova-Malinovska, D.; Angelov, O. I.

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  7. Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

    Science.gov (United States)

    Winter, Gregory T.; Wilhide, Joshua A.; LaCourse, William R.

    2016-02-01

    Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

  8. The thin layer of Warm Ionized Gas: towards a 3-D reconstruction of the spatial distribution of HII regions

    OpenAIRE

    Paladini, Roberta; Davies, Rod; DeZotti, Gianfranco

    2002-01-01

    HII regions are known to contribute to the so-called thin layer of the diffuse Warm Ionized Gas. In order to constrain this contribution, we reconstruct the 3-D distribution of the sources. A detailed spatial analysis of the largest up-to-date sample of HII regions is presented.

  9. NATO Advanced Research Workshop on Ionization of Solids by Heavy Particles

    CERN Document Server

    1993-01-01

    This book collects the papers presented at the NATO Advanced Research Workshop on "Ionization of Solids by Heavy Particles", held in Giardini-Naxos (Taormina), Italy, on June 1 -5, 1992. The meeting was the first to gather scientists to discuss the physics of electron emission and other ionization effects occurring during the interaction of heavy particles with condensed matter. The central problem in the field is how to use observations of electron emission and final radiation damage to understand what happens inside the solid, like excitation mechanisms, the propagation of the electronic excitation along different pathways, and surface effects. The ARW began with a brief survey of the field, stressing the unknowns. It was pointed out that ionization theories can only address the very particular case of weak perturbations. For this problem, this meant high speed, low-charged projectiles (a perturbation treatment of interactions with slow, highly charged ions was later presented). Only semi-empirical ...

  10. Thin-Layer Chromatography/Desorption Electrospray Ionization Mass Spectrometry: Investigation of Goldenseal Alkaloids

    Energy Technology Data Exchange (ETDEWEB)

    Van Berkel, Gary J [ORNL; Tomkins, Bruce A [ORNL; Kertesz, Vilmos [ORNL

    2007-01-01

    Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm x 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed RF value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile proving superior to methanol. The detection levels (ca. 5 ng each or 14 -28 pmol) in mass spectral full scan mode were determined statistically from the calibration curves (2.5 - 100 pmol) for the standards berberine, palmatine and hydrastinine spotted as a mixture and separated on the plates. Qualitative screening of the major alkaloids present in six different over-the-counter "goldenseal" dietary supplements was accomplished by obtaining full scan mass spectra during surface scans along the development lane in the direction of increasing RF value. In one sample, alkaloids were detected that strongly suggested the presence of at least one additional herb undeclared on the product label. These same data indicated the misidentification of one of the alkaloids in the TLC literature. Quantities of the alkaloids present in two of the samples determined using the mass spectral data were in reasonable agreement with the label values indicating the quantitative ability of

  11. Grain growth in thin Al films during deposition from partially ionized vapor

    Science.gov (United States)

    Gusev, I. V.; Mokhniuk, A. A.

    2016-07-01

    Grain growth in thin Al films during deposition from partially ionized vapor flux with simultaneous self-ion bombardment was studied in this work. The films were deposited at constant ion energy of 940 eV and total specific power of 0.4 W/cm2 while the deposition time t of 6 s to 246 s and the resulting substrate temperature (Ts/Tm of 0.35-0.96) were varied. Thin continuous Al films exhibited normal grain growth through the entire experimental range of deposition time without limitation of grain growth by the film thickness effect. Three kinetic stages of the grain growth were observed within 100 s of deposition time: the first one exhibits very slow grain growth, accelerated grain growth occurs in the second stage and then it rapidly changes to a retardation and stagnation mode in the third stage. Large average grain sizes Dg up to 11.3 μm at film thickness of 1.4 μm and integral grain growth rates up to 0.16 μm/s were observed in this study. The experimental results were evaluated against various mechanisms of inhibition of grain growth. An estimate of the effective activation energy of the grain growth yields a value of 0.27 eV which is lower than that of the bulk Al and much higher than the activation energy of surface self-diffusion on (1 1 1)Al monocrystal. The power law Dg = (k t)0.5 gives good match with experimental results in the initial deposition phase preceding the grain growth retardation, while another model that is based on the grain size dependent pinning force adequately explains the entire grain size dependence on time. It is deemed both ion enhanced film/surface interaction and impurities on one side and thermal grooves on another side contribute to the rapid retardation of the grain grooves commencing the second growth stage.

  12. Thin layer chromatography coupled to paper spray ionization mass spectrometry for cocaine and its adulterants analysis.

    Science.gov (United States)

    De Carvalho, Thays C; Tosato, Flavia; Souza, Lindamara M; Santos, Heloa; Merlo, Bianca B; Ortiz, Rafael S; Rodrigues, Rayza R T; Filgueiras, Paulo R; França, Hildegardo S; Augusti, Rodinei; Romão, Wanderson; Vaz, Boniek G

    2016-05-01

    Thin layer chromatography (TLC) is a simple and inexpensive type of chromatography that is extensively used in forensic laboratories for drugs of abuse analysis. In this work, TLC is optimized to analyze cocaine and its adulterants (caffeine, benzocaine, lidocaine and phenacetin) in which the sensitivity (visual determination of LOD from 0.5 to 14mgmL(-1)) and the selectivity (from the study of three different eluents: CHCl3:CH3OH:HCOOHglacial (75:20:5v%), (C2H5)2O:CHCl3 (50:50v%) and CH3OH:NH4OH (100:1.5v%)) were evaluated. Aiming to improve these figures of merit, the TLC spots were identified and quantified (linearity with R(2)>0.98) by the paper spray ionization mass spectrometry (PS-MS), reaching now lower LOD values (>1.0μgmL(-1)). The method developed in this work open up perspective of enhancing the reliability of traditional and routine TLC analysis employed in the criminal expertise units. Higher sensitivity, selectivity and rapidity can be provided in forensic reports, besides the possibility of quantitative analysis. Due to the great simplicity, the PS(+)-MS technique can also be coupled directly to other separation techniques such as the paper chromatography and can still be used in analyses of LSD blotter, documents and synthetic drugs. PMID:26970868

  13. The characterization of the Advanced Markus ionization chamber for use in reference electron dosimetry in the UK

    International Nuclear Information System (INIS)

    The IPEM Code of Practice (IPEM 2003) for electron dosimetry for radiotherapy beams recommends design requirements for parallel-plate ionization chambers used to determine absorbed dose to water in an electron beam. The Classic Markus design has been found not to meet these requirements. The Advanced Markus ionization chamber has been designed to rectify the problems associated with the Classic Markus ionization chamber. The response of three Advanced Markus ionization chambers was investigated and compared to the designated chamber types. Absorbed dose to water calibration factors were derived at the National Physical Laboratory (NPL) for each ionization chamber at seven electron energies in the range nominally 4-19 MeV. Investigations were carried out into chamber settling, polarity effects, ion recombination and the chamber perturbation. The response of the ionization chambers in a clinical beam was also investigated. In general all three Advanced Markus ionization chambers showed the same energy response. The magnitude of the polarity effect was typically 5% at a nominal energy of 4 MeV. There was discrepancy between the polarity measurements made at the NPL and in the clinic. The recommendation of this study is that this chamber type is not suitable for reference dosimetry in electron beams

  14. The influence of non-parallelism of electron and positron velocities upon high-energy e+e− pair ionization loss in thin plate

    International Nuclear Information System (INIS)

    The problem of high-energy electron–positron pair ionization loss in thin plate is considered. It is shown that in this case the approximation of parallel electron and positron velocities which is usually used for calculation of pair ionization loss may not be strictly valid and the existence of non-zero angle of pair divergence can lead to slight suppression of the Chudakov effect of pair ionization loss reduction. The conditions under which such suppression has noticeable value are discussed

  15. Advances in targetry with thin diamond-like carbon foils

    CERN Document Server

    Liechtenstein, V K; Olshanski, E D; Repnow, R; Levin, J; Hellborg, R; Persson, P; Schenkel, T

    2002-01-01

    Thin and stable diamond-like carbon (DLC) foils, which were fabricated at the Kurchatov Institute by sputter deposition, have proved recently to be advantageous for stripping and secondary electron timing of high energy heavy ions in a number of accelerator experiments. This resulted in expanding applications of these DLC foils which necessitated further development efforts directed toward the following applications of DLC targetry: (i) thin stripper foils for lower energy tandem accelerators, (ii) enlarged (up to 66 mm in diameter) stop foils for improved time-of-flight elastic recoil detection ion beam analysis, and (iii) ultra-thin (about 0.6 mu g/cm sup 2) DLC foils for some fundamental and applied physics experiments. Along with the fabrication of thin DLC stripper foils for tandem accelerators, much thicker (up to 200 mu g/cm sup 2) foils for post-stripping of heavy-ion beams in higher energy linacs, are within reach.

  16. Advanced RBS analysis of thin films in micro-electronics

    International Nuclear Information System (INIS)

    Rutherford Backscattering Spectrometry (RBS) is well known for quantitative compositional analysis of thin films. As the semiconductor industry heads towards shrinking device dimensions and new materials, there is a need for accurate and reliable characterization of very thin films. With a careful selection of RBS analysis conditions and instrumentation, a depth resolution down to 1 nm can be obtained. Mainly the reduction in analysis energy and improved detector resolution contribute to this enhancement. At the same time it is demonstrated that the sensitivity of RBS improves to below the 1% level. The effect of reduction in analysis energy will be illustrated in the study on the segregation process of Cu on a Al(Cu) surface. Furthermore, it will be demonstrated that the use of dedicated spectrometers to improve detector resolution leads to extreme depth resolutions allowing the analysis of SiGe layers less than 10 nm thick and the analysis of thin oxynitrides which are only 2.5 nm thick

  17. Fabrication and characterization of advanced Organic Thin Film Transistors

    OpenAIRE

    Scaldaferri, Rossana

    2009-01-01

    The thesis aims to the development of Organic Thin Film Transistors and more complex devices based on organic materials. The experimental work demonstrates the possibility to manufacture transistors and more complex circuits with innovative polymers and technologies, leading to an experimental validation of the possibility to realize all-organic devices.

  18. Bias-induced migration of ionized donors in amorphous oxide semiconductor thin-film transistors with full bottom-gate and partial top-gate structures

    Directory of Open Access Journals (Sweden)

    Mallory Mativenga

    2012-09-01

    Full Text Available Bias-induced charge migration in amorphous oxide semiconductor thin-film transistors (TFTs confirmed by overshoots of mobility after bias stressing dual gated TFTs is presented. The overshoots in mobility are reversible and only occur in TFTs with a full bottom-gate (covers the whole channel and partial top-gate (covers only a portion of the channel, indicating a bias-induced uneven distribution of ionized donors: Ionized donors migrate towards the region of the channel that is located underneath the partial top-gate and the decrease in the density of ionized donors in the uncovered portion results in the reversible increase in mobility.

  19. Advanced methods for titanium (IV) oxide thin functional coatings

    Czech Academy of Sciences Publication Activity Database

    Kment, Štěpán; Klusoň, P.; Bartková, H.; Krýsa, J.; Churpita, Olexandr; Čada, Martin; Virostko, Petr; Kohout, Michal; Hubička, Zdeněk

    2008-01-01

    Roč. 202, č. 11 (2008), s. 2379-2383. ISSN 0257-8972 R&D Projects: GA MŠk(CZ) 1M06002; GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z10100522 Keywords : plasma deposition * sol-gel * thin layers * photoactivity * self-assembly Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.860, year: 2008

  20. Advances in polycrystalline thin-film photovoltaics for space applications

    Science.gov (United States)

    Lanning, Bruce R.; Armstrong, Joseph H.; Misra, Mohan S.

    1994-01-01

    Polycrystalline, thin-film photovoltaics represent one of the few (if not the only) renewable power sources which has the potential to satisfy the demanding technical requirements for future space applications. The demand in space is for deployable, flexible arrays with high power-to-weight ratios and long-term stability (15-20 years). In addition, there is also the demand that these arrays be produced by scalable, low-cost, high yield, processes. An approach to significantly reduce costs and increase reliability is to interconnect individual cells series via monolithic integration. Both CIS and CdTe semiconductor films are optimum absorber materials for thin-film n-p heterojunction solar cells, having band gaps between 0.9-1.5 ev and demonstrated small area efficiencies, with cadmium sulfide window layers, above 16.5 percent. Both CIS and CdTe polycrystalline thin-film cells have been produced on a laboratory scale by a variety of physical and chemical deposition methods, including evaporation, sputtering, and electrodeposition. Translating laboratory processes which yield these high efficiency, small area cells into the design of a manufacturing process capable of producing 1-sq ft modules, however, requires a quantitative understanding of each individual step in the process and its (each step) effect on overall module performance. With a proper quantification and understanding of material transport and reactivity for each individual step, manufacturing process can be designed that is not 'reactor-specific' and can be controlled intelligently with the design parameters of the process. The objective of this paper is to present an overview of the current efforts at MMC to develop large-scale manufacturing processes for both CIS and CdTe thin-film polycrystalline modules. CIS cells/modules are fabricated in a 'substrate configuration' by physical vapor deposition techniques and CdTe cells/modules are fabricated in a 'superstrate configuration' by wet chemical

  1. Recent advances in the estimation of genetic risks of exposure to ionizing radiation

    International Nuclear Information System (INIS)

    This paper reviews the major advances that have occurred during the last few years in the estimation of genetic risks of exposure of human populations to ionizing radiation. Among these are: (i) an upward revision of the estimates of the baseline frequencies of Mendelian diseases (from 1.25% to 2.4%); (ii) the conceptual change to the use of a doubling dose based on human data on spontaneous mutation rates and mouse data on induced mutation rates (from the one based entirely on mouse data on spontaneous and induced mutation rates, which was the case thus far); (iii) the fuller development of the concept of mutation component (MC) and its application to predict the responsiveness of Mendelian and chronic multi factorial diseases to induced mutations; (iv) the introduction of the concept that the major adverse effects of radiation exposure of human germ cells are likely to be manifest as multi-system developmental abnormalities and (v) the introduction of concept of potential recoverability correction factor (PRCF) to bridge the gap between induced mutations studied in mice and the risk of genetic disease in humans are reviewed

  2. Physics of thin films advances in research and development, v.6

    CERN Document Server

    Francombe, Maurice H

    1971-01-01

    Physics of Thin Films: Advances in Research and Development, Volume 6 reviews the rapid progress that has been made in research and development concerning the physics of thin films, with emphasis on metallic films. Topics covered include anodic oxide films, thin metal films and wires, and multilayer magnetic films. This volume is comprised of five chapters and begins with a discussion on the dielectric properties and the technique of plasma anodization which are relevant to the applications of anodic oxide films in electronic devices. Conduction, polarization, and dielectric breakdown effects

  3. Advanced morphological analysis of patterns of thin anodic porous alumina

    International Nuclear Information System (INIS)

    Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for the thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing

  4. Advanced morphological analysis of patterns of thin anodic porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Toccafondi, C. [Istituto Italiano di Tecnologia, Department of Nanophysics, Via Morego 30, Genova I 16163 (Italy); Istituto Italiano di Tecnologia, Department of Nanostructures, Via Morego 30, Genova I 16163 (Italy); Stępniowski, W.J. [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Leoncini, M. [Istituto Italiano di Tecnologia, Department of Nanostructures, Via Morego 30, Genova I 16163 (Italy); Salerno, M., E-mail: marco.salerno@iit.it [Istituto Italiano di Tecnologia, Department of Nanophysics, Via Morego 30, Genova I 16163 (Italy)

    2014-08-15

    Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for the thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing.

  5. Advanced characterization techniques for thin film solar cells

    CERN Document Server

    Rau, Uwe; Kirchartz, Thomas

    2011-01-01

    Written by scientists from leading institutes in Germany, USA and Spain who use these techniques as the core of their scientific work and who have a precise idea of what is relevant for photovoltaic devices, this text contains concise and comprehensive lecture-like chapters on specific research methods.They focus on emerging, specialized techniques that are new to the field of photovoltaics yet have a proven relevance. However, since new methods need to be judged according to their implications for photovoltaic devices, a clear introductory chapter describes the basic physics of thin-film

  6. Thin film design for advanced thermochromic smart radiator devices

    Institute of Scientific and Technical Information of China (English)

    Feng Yu-Dong; Wang Zhi-Min; Ma Ya-Li; Zhang Fu-Jia

    2007-01-01

    This paper describes the research on the materials and design methods for advanced smart radiator devices (SRDs) on large-area flexible substrates utilized on spacecraft. The functional material is thermochromic vanadium dioxide. The coating design of 3RD is similar to the design of broadband filter coatings in a mid-infrared region. The multilayer coatings have complex structures. Coating materials must be highly transparent in a required spectrum region and also mechanically robust enough to endure the influence from the rigorous environments of outer space. The number of layers must be very small, suitable for the deposition on large-area flexible substrates. All the coatings are designed initially based on optical calculation and practical experience, and then optimized by the TFCALC software. Several designs are described and compared with each other. The results show that the emittance variability of the designed SRDs is great than 400%, more advanced than the reported ones.

  7. Thin dielectric film thickness determination by advanced transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, A.C.; Foran, B.; Kisielowski, C.; Muller, D.; Pennycook, S.; Principe, E.; Stemmer, S.

    2003-09-01

    High Resolution Transmission Electron Microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by non-specialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods was steadily improved reaching now into the sub Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this paper, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this paper is the proposal of a reproducible method for film thickness determination.

  8. Fluctuations and probable values of ionization energy losses of relativistic electrons in thin gas layers

    International Nuclear Information System (INIS)

    Calculations of fluctuations and probable values of ionization energy losses of relativistic electrons in gas layers (Ar+10%CH4) of different thickness are carried out by the Monte Carlo method, with account of the δ-electron transfer under real experimental conditions. The calculation results agree to the experimental data with an accuracy of ≤ 50%. The δ-electron escape from the sensitive part of absorber (of a few cm thick) is shown to result in the loss of the Landau distribution high-energy tail. This brings to the fact that in case of long and narrow absorbers the Landau distribution narrows and becomes mor Gaussian. In case of heavy ions this phenomenon is observed of ∼ 1 cm thick gas layers

  9. Advances in thin-film solar cells for lightweight space photovoltaic power

    Science.gov (United States)

    Landis, Geoffrey A.; Bailey, Sheila G.; Flood, Dennis J.

    1989-01-01

    The present stature and current research directions of photovoltaic arrays as primary power systems for space are reviewed. There have recently been great advances in the technology of thin-film solar cells for terrestrial applications. In a thin-film solar cell the thickness of the active element is only a few microns; transfer of this technology to space arrays could result in ultralow-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe2) and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon:hydrogen and alloys. The best experimental efficiency on thin-film solar cells to date is 12 percent AMO for CuIn Se2. This efficiency is likely to be increased in the next few years. The radiation tolerance of thin-film materials is far greater than that of single-crystal materials. CuIn Se2 shows no degradation when exposed to 1 MeV electrons. Experimental evidence also suggests that most of all of the radiation damage on thin-films can be removed by a low temperature anneal. The possibility of thin-film multibandgap cascade solar cells is discussed, including the tradeoffs between monolithic and mechanically stacked cells. The best current efficiency for a cascade is 12.5 percent AMO for an amorphous silicon on CuInSe2 multibandgap combination. Higher efficiencies are expected in the future. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovolatic arrays may be a mission-enabling technology.

  10. Advanced electrical simulation of thin film solar cells

    International Nuclear Information System (INIS)

    Advanced electrical simulation of copper indium gallium diselenide solar cells is illustrated by setting up a demonstration case in SCAPS (Solar Cell Capacitance Simulator), the solar cell simulation programme of the University of Gent. The model includes band gap grading, multivalent defects and metastable transitions between defects. This simplified demonstration model clearly and quantitatively illustrates some topics that were extensively discussed in recent literature: metastable defects exist in either an acceptor or in a donor configuration; the occupation of these configurations is set during initial conditions at higher temperature, and then frozen in during cell operation at lower temperature. These occupations can strongly influence the effective doping profile in the absorber, and hence possible energy barriers in the structure. The dependence of such barriers on the initial conditions and on the operating voltage can cause a considerable dependence of the current–voltage characteristics on the initial conditions, especially of the fill factor. At the same time, the demonstration model illustrates some of the recent extensions of SCAPS. - Highlights: ► SCAPS, the Solar Cell Capacitance Simulator of UGent is freely available. ► SCAPS is keeping up with the sophistication of state-of-the-art solar cells. ► It can now handle: multivalent and metastable defects; grading of all properties. ► It is shown how metastable defects can lead to metastable cell characteristics. ► A relation conduction band barrier-fill factor is numerically established

  11. New surfaces for desorption electrospray ionization mass spectrometry: porous silicon and ultra-thin layer chromatography plates.

    Science.gov (United States)

    Kauppila, Tiina J; Talaty, Nari; Salo, Piia K; Kotiaho, Tapio; Kostiainen, Risto; Cooks, R Graham

    2006-01-01

    The performance of nanoporous silicon (pSi) and ultra-thin layer chromatography (UTLC) plates as surfaces for desorption electrospray ionization (DESI) was compared with that of polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE), both popular surfaces in previous DESI studies. The limits of detection (LODs) and other analytical characteristics for six different test compounds were determined using all four surfaces. The LODs for the compounds were in the fmol-pmol (pg-ng) range. The LODs with the pSi surface were further improved for each of the compounds when heat was applied to the surface during sample application which gave LODs as low as or lower than those achieved with PMMA and PTFE. The UTLC plates were successfully used as a rapid means of chromatographic separation prior to DESI-MS analysis. Another advantage achieved using the newer pSi and UTLC surfaces was increased speed of analysis, associated with drying of solution-phase samples. This took place immediately at the UTLC surface and it could be achieved rapidly by gently heating the pSi surface. The presence of salts in the sample did not cause suppression of the analyte signal with any of the surfaces. PMID:16773669

  12. NATO Advanced Research Workshop on Thin Film Growth Techniques for Low-Dimensional Structures

    CERN Document Server

    Parkin, S; Dobson, P; Neave, J; Arrott, A

    1987-01-01

    This work represents the account of a NATO Advanced Research Workshop on "Thin Film Growth Techniques for Low Dimensional Structures", held at the University of Sussex, Brighton, England from 15-19 Sept. 1986. The objective of the workshop was to review the problems of the growth and characterisation of thin semiconductor and metal layers. Recent advances in deposition techniques have made it possible to design new material which is based on ultra-thin layers and this is now posing challenges for scientists, technologists and engineers in the assessment and utilisation of such new material. Molecular beam epitaxy (MBE) has become well established as a method for growing thin single crystal layers of semiconductors. Until recently, MBE was confined to the growth of III-V compounds and alloys, but now it is being used for group IV semiconductors and II-VI compounds. Examples of such work are given in this volume. MBE has one major advantage over other crystal growth techniques in that the structure of the growi...

  13. Physics of Partially Ionized Plasmas

    Science.gov (United States)

    Krishan, Vinod

    2016-05-01

    Figures; Preface; 1. Partially ionized plasmas here and everywhere; 2. Multifluid description of partially ionized plasmas; 3. Equilibrium of partially ionized plasmas; 4. Waves in partially ionized plasmas; 5. Advanced topics in partially ionized plasmas; 6. Research problems in partially ionized plasmas; Supplementary matter; Index.

  14. Adsorption of Emerging Ionizable Contaminants on Carbon Nanotubes: Advancements and Challenges

    OpenAIRE

    Xingmao Ma; Sarang Agarwal

    2016-01-01

    The superior adsorption capacity of carbon nanotubes has been well recognized and there is a wealth of information in the literature concerning the adsorption of unionized organic pollutants on carbon nanotubes. Recently, the adsorption of emerging environmental pollutants, most of which are ionizable, has attracted increasing attention due to the heightened concerns about the accumulation of these emerging contaminants in the environment. These recent studies suggest that the adsorption of e...

  15. Rapid identification of siderophores by combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Hayen, Heiko; Volmer, Dietrich A

    2005-01-01

    The investigation of a combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry (TLC/MALDI-MS) method for the analysis of siderophores from microbial samples is described. The investigated siderophores were enterobactin, ferrioxamine B, ferrichrome, ferrirhodin, rhodotorulic acid and coprogen. Solid-phase extraction was employed to recover the siderophores from the microbial samples. After visualization of the spots via spraying with ferric chloride or chrome azurol sulfonate assay solution, the MALDI matrix was applied to the gel surface. Several TLC/MALDI experimental parameters were optimized, such as type and concentration of MALDI matrix, as well as the type and composition of solvent to facilitate analyte transport from the inside of the TLC gel to the surface. The impact of these parameters on sensitivity, precision and ion formation of the various siderophores was studied. The detection limits for the investigated siderophores were in the range 1-4 pmol. These values were about 4-24 times higher than the detection limits obtained directly from stainless steel MALDI targets. The differences were most likely due to incomplete transport of the 'trapped' analyte molecules from the deeper layers of the TLC gel to the surface and into the matrix layer. In addition, chromatographic band broadening spread the analyte further in TLC as compared with the steel plates, resulting in less analyte per surface area. The identification of the siderophores was aided by concurrently applying a Ga(III) nitrate solution to the TLC plate during the visualization step. The resulting formation of Ga(III) complexes lead to distinctive (69)Ga/(71)Ga isotope patterns in the mass spectra. The versatility of the TLC/MALDI-MS assay was demonstrated by using it to analyze siderophores in a Pseudomonas aeruginosa sample. An iron-binding compound was identified in the sample, namely pyochelin (2-(2-o-hydroxyphenyl-2-thiazolin-4-yl)-3

  16. Full potential of radial junction Si thin film solar cells with advanced junction materials and design

    Science.gov (United States)

    Qian, Shengyi; Misra, Soumyadeep; Lu, Jiawen; Yu, Zhongwei; Yu, Linwei; Xu, Jun; Wang, Junzhuan; Xu, Ling; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-07-01

    Combining advanced materials and junction design in nanowire-based thin film solar cells requires a different thinking of the optimization strategy, which is critical to fulfill the potential of nano-structured photovoltaics. Based on a comprehensive knowledge of the junction materials involved in the multilayer stack, we demonstrate here, in both experimental and theoretical manners, the potential of hydrogenated amorphous Si (a-Si:H) thin film solar cells in a radial junction (RJ) configuration. Resting upon a solid experimental basis, we also assess a more advanced tandem RJ structure with radially stacking a-Si:H/nanocrystalline Si (nc-Si:H) PIN junctions, and show that a balanced photo-current generation with a short circuit current density of Jsc = 14.2 mA/cm2 can be achieved in a tandem RJ cell, while reducing the expensive nc-Si:H absorber thickness from 1-3 μ m (in planar tandem cells) to only 120 nm. These results provide a clearly charted route towards a high performance Si thin film photovoltaics.

  17. Spray-on Thin Film PV Solar Cells: Advances, Potentials and Challenges

    Directory of Open Access Journals (Sweden)

    Morteza Eslamian

    2014-01-01

    Full Text Available The capability to fabricate photovoltaic (PV solar cells on a large scale and at a competitive price is a milestone waiting to be achieved. Currently, such a fabrication method is lacking because the effective methods are either difficult to scale up or expensive due to the necessity for fabrication in a vacuum environment. Nevertheless, for a class of thin film solar cells, in which the solar cell materials can be processed in a solution, up scalable and vacuum-free fabrication techniques can be envisioned. In this context, all or some layers of polymer, dye-sensitized, quantum dot, and copper indium gallium selenide thin film solar cells illustrate some examples that may be processed in solution. The solution-processed materials may be transferred to the substrate by atomizing the solution and carrying the spray droplets to the substrate, a process that will form a thin film after evaporation of the solvent. Spray coating is performed at atmospheric pressure using low cost equipment with a roll-to-roll process capability, making it an attractive fabrication technique, provided that fairly uniform layers with high charge carrier separation and transport capability can be made. In this paper, the feasibility, the recent advances and challenges of fabricating spray-on thin film solar cells, the dynamics of spray and droplet impaction on the substrate, the photo-induced electron transfer in spray-on solar cells, the challenges on characterization and simulation, and the commercialization status of spray-on solar cells are discussed.

  18. Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

    Directory of Open Access Journals (Sweden)

    Suzan Biran Ay

    2015-01-01

    Full Text Available Large-area catalytic thin films offer great potential for green technology applications in order to save energy, combat pollution, and reduce global warming. These films, either embedded with nanoparticles, shaped with nanostructuring techniques, hybridized with other systems, or functionalized with bionanotechnological methods, can include many different surface properties including photocatalytic, antifouling, abrasion resistant and mechanically resistive, self-cleaning, antibacterial, hydrophobic, and oleophobic features. Thus, surface functionalization with such advanced structuring methods is of significance to increase the performance and wide usage of large-area thin film coatings specifically for environmental remediation. In this review, we focus on methods to increase the efficiency of catalytic reactions in thin film and hence improve the performance in relevant applications while eliminating high cost with the purpose of widespread usage. However, we also include the most recent hybrid architectures, which have potential to make a transformational change in surface applications as soon as high quality and large area production techniques are available. Hence, we present and discuss research studies regarding both organic and inorganic methods that are used to structure thin films that have potential for large-area and eco-friendly coatings.

  19. Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

    International Nuclear Information System (INIS)

    Graphical abstract: ZnO nanostructures have shown binding of biomolecules in desired orientation with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, their compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes them suitable candidate for future small integrated biosensor devices. This review highlights various approaches to synthesize ZnO nanostructures and thin films, and their applications in biosensor technology. Highlights: ► This review highlights various approaches to synthesize ZnO nanostructures and thin films. ► Article highlights the importance of ZnO nanostructures as biosensor matrix. ► Article highlights the advances in various biosensors based on ZnO nanostructures. ► Article describes the potential of ZnO based biosensor for new generation healthcare devices. - Abstract: Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO nanostructures suitable candidate for future small integrated biosensor devices. This review

  20. Advanced liquid chromatography-mass spectrometry interface based on electron ionization.

    Science.gov (United States)

    Cappiello, A; Famiglini, G; Pierini, E; Palma, P; Trufelli, H

    2007-07-15

    Major progress in interfacing liquid chromatography and electron ionization mass spectrometry is presented. The minimalism of the first prototype, called the Direct-EI interface, has been widely refined, improved, and applied to modern instrumentation. The simple interfacing principle is based on the straight connection between a nanoHPLC system and a mass spectrometer equipped with an EI source forming a solid and reliable unicum resembling the immediacy and straightforwardness of GC/MS. The interface shows a superior performance in the analysis of small-medium molecular weight compounds, especially when compared to its predecessors, and a unique trait that excels particularly in the following aspects: (1) It delivers high-quality, fully library matchable mass spectra of most sub-1 kDa molecules amenable by HPLC. (2) It is a chemical ionization free interface (unless operated intentionally) with accurate reproduction of the expected isotope ion abundances. (3) Response is never influenced by matrix components in the sample or in the mobile phase (nonvolatile salts are also well accepted). A deep evaluation of these aspects is presented and discussed in detail. Other characteristics of the interface performance such as limits of detections, range of linear response, and intra- and interday signal stability were also considered. The usefulness of the interface has been tested in a few real-world applications where matrix components played a detrimental role with other LC/MS techniques. PMID:17569502

  1. Optical coherence tomography demonstrating macular retinal nerve fiber thinning in advanced optic disc drusen

    OpenAIRE

    Ali Hassan; Pieter Gouws

    2014-01-01

    Optic disc drusen (ODD) are extracellular proteinaceous excrescences in the optic nerve head. They enlarge over time and can cause damage to nerve fibers with resulting loss of visual field. The authors report a case of advanced ODD in which macular optical coherence tomography demonstrated retinal nerve fiber thinning. A single case report of a 42-year-old woman with known ODD presented to the eye clinic with worsening field of vision which was impacting on her daily life. The patient was su...

  2. Using electrospray-assisted laser desorption/ionization mass spectrometry to characterize organic compounds separated on thin-layer chromatography plates.

    Science.gov (United States)

    Lin, Shu-Yao; Huang, Min-Zong; Chang, Hui-Chiu; Shiea, Jentaie

    2007-11-15

    Electrospray-assisted laser desorption/ionization (ELDI), an ionization method that combines laser desorption and electrospray ionization (ESI), can be used under ambient conditions to characterize organic compounds (including FD&C dyes, amines, extracts of a drug tablet) separated in the central track on a thin-layer chromatography (TLC) plate coated with either reversed-phase C18 particles or normal-phase silica gel. After drying, the TLC plate was placed on an acrylic sample holder set in front of the sampling skimmer of an ion trap mass analyzer. The chemicals at the center of the TLC plate were analyzed by pushing the sample holder into the path of a laser beam with a syringe pump. The molecules in the sample spot were desorbed by continuously irradiating the surface of the TLC plate with a pulsed nitrogen laser. Then, the desorbed sample molecules entered an ESI plume where they were ionized through the reactions with the charged species (including protons, hydronium ions and their cluster ions, solvent ions, and charged droplets) generated by electrospraying a methanol/water solution. MS/MS analyses were also performed to further characterize the analytes. The detection limit of TLC/ELDI/MS is approximately 10(-6) M. This was evaluated by using FD&C red dye as the standard. A linear relationship was found for the calibration curve with the concentration of FD&C red dye ranged from 10(-3) to 10(-6) M. PMID:17929897

  3. Advanced methods for light trapping in optically thin silicon solar cells

    Science.gov (United States)

    Nagel, James Richard

    2011-12-01

    The field of light trapping is the study of how best to absorb light in a thin film of material when most light either reflects away at the surface or transmits straight through to the other side. This has tremendous application to the field of photovoltaics where thin silicon films can be manufactured cheaply, but also fail to capture all of the available photons in the solar spectrum. Advancements in light trapping therefore bring us closer to the day when photovoltaic devices may reach grid parity with traditional fossil fuels on the electrical energy market. This dissertation advances our understanding of light trapping by first modeling the effects of loss in planar dielectric waveguides. The mathematical framework developed here can be used to model any arbitrary three-layer structure with mixed gain or loss and then extract the total field solution for the guided modes. It is found that lossy waveguides possess a greater number of eigenmodes than their lossless counterparts, and that these "loss guided" modes attenuate much more rapidly than conventional modes. Another contribution from this dissertation is the exploration of light trapping through the use of dielectric nanospheres embedded directly within the active layer of a thin silicon film. The primary benefit to this approach is that the device can utilize a surface nitride layer serving as an antireflective coating while still retaining the benefits of light trapping within the film. The end result is that light trapping and light injection are effectively decoupled from each other and may be independently optimized within a single photovoltaic device. The final contribution from this work is a direct numerical comparison between multiple light trapping schemes. This allows us to quantify the relative performances of various design techniques against one another and objectively determine which ideas tend to capture the most light. Using numerical simulation, this work directly compares the absorption

  4. Effect of total ionizing dose radiation on the 0.25μm RF PDSOI nMOSFETs with thin gate oxide

    Institute of Scientific and Technical Information of China (English)

    Liu Mengxin; Han Zhengsheng; Bi Jinshun; Fan Xuemei; Liu Gang; Du Huan

    2009-01-01

    Thin gate oxide radio frequency (RF) PDSOI nMOSFETs that are suitable for integration with 0.1 μm SO1 CMOS technology are fabricated, and the total ionizing dose radiation responses of the nMOSFETs having four different device structures are characterized and compared for an equivalent gamma dose up to 1 Mrad (Si), using the front and back gate threshold voltages, off-state leakage, transconductance and output characteristics to assess direct current (DC) performance. Moreover, the frequency response of these devices under total ionizing dose radiation is presented, such as small-signal current gain and maximum available/stable gain. The results indicate that all the RF PDSOI nMOSFETs show significant degradation in both DC and RF characteristics after radiation, in particular to the float body nMOS. By comparison with the gate backside body contact (GBBC) structure and the body tied to source (BTS) contact structure, the low barrier body contact (LBBC) structure is more effective and excellent in the hardness of total ionizing dose radiation although there are some sacrifices in drive current, switching speed and high frequency response.

  5. Recent advances and remaining challenges in thin-film silicon photovoltaic technology

    Directory of Open Access Journals (Sweden)

    F. Meillaud

    2015-09-01

    Full Text Available This contribution reviews some of the latest achievements and challenges in thin-film silicon photovoltaic (PV technology based on amorphous and nanocrystalline silicon and their alloys. We address material and device developments, including (i improved plasma deposition processes to achieve high-quality dense absorber materials; (ii absorber layers based on silicon tetrafluoride, which lead to enhanced absorption in the near-infrared and yield outstanding short-circuit current densities; (iii dedicated optimization of the interfaces and device architecture, as well as (iv enhanced light harvesting by means of multi-scale textured substrates and reduced parasitic absorption in the non-active layers. This paper will describe how, by combining all of these advances along with precise control of plasmas over large areas, key results have been achieved in recent years, at both the cell and large-area module level, with stabilized efficiencies of over 13 and 12%, respectively.

  6. Electrospun fibrous thin film microextraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human plasma.

    Science.gov (United States)

    Chen, Di; Hu, Yu-Ning; Hussain, Dilshad; Zhu, Gang-Tian; Huang, Yun-Qing; Feng, Yu-Qi

    2016-05-15

    Appropriate sample preparations prior to analysis can significantly enhance the sensitivity of ambient ionization techniques, especially during the enrichment or purification of analytes in the presence of complex biological matrix. Here in, we developed a rapid analysis method by the combination of thin film microextraction (TFME) and desorption corona beam ionization (DCBI) for the determination of antidepressants in human plasma. Thin films used for extraction consisted of sub-micron sized highly ordered mesoporous silica-carbon composite fibers (OMSCFs), simply prepared by electrospinning and subsequent carbonization. Typically, OMSCFs thin film was immersed into the diluted plasma for extraction of target analytes and then directly subjected to the DCBI-MS for detection. Size-exclusion effect of mesopores contributed to avoid of the protein precipitation step prior to extraction. Mass transfer was benefited from high surface-to-volume ratio which is attributed to macroporous network and ordered mesostructures. Moreover, the OMSCFs provided mixed-mode hydrophobic/ion-exchange interactions towards target analytes. Thus, the detection sensitivity was greatly improved due to effective enrichment of the target analytes and elimination of matrix interferences. After optimization of several parameters related to extraction performance, the proposed method was eventually applied for the determination of three antidepressants in human plasma. The calibration curves were plotted in the range of 5-1000ng/mL with acceptable linearity (R(2) >0.983). The limits of detection (S/N=3) of three antidepressants were in ranges of 0.3-1ng/mL. Reproducibility was achieved with RSD less than 17.6% and the relative recoveries were in ranges of 83.6-116.9%. Taken together, TFME-DCBI-MS method offers a powerful capacity for rapid analysis to achieve much-improved sensitivity. PMID:26992510

  7. Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare though Sodium-like Ions

    CERN Document Server

    Bryans, P; Gorczyca, T W; Laming, J M; Mitthumsiri, W; Savin, D W

    2006-01-01

    Reliably interpreting spectra from electron-ionized cosmic plasmas requires accurate ionization balance calculations for the plasma in question. However, much of the atomic data needed for these calculations have not been generated using modern theoretical methods and are often highly suspect. This translates directly into the reliability of the collisional ionization equilibrium (CIE) calculations. We make use of state-of-the-art calculations of dielectronic recombination (DR) rate coefficients for the hydrogenic through Na-like ions of all elements from He up to and including Zn. We also make use of state-of-the-art radiative recombination (RR) rate coefficient calculations for the bare through Na-like ions of all elements from H through to Zn. Here we present improved CIE calculations for temperatures from $10^4$ to $10^9$ K using our data and the recommended electron impact ionization data of \\citet{Mazz98a} for elements up to and including Ni and Mazzotta (private communication) for Cu and Zn. DR and RR ...

  8. Advanced fabrication method for the preparation of MOF thin films: Liquid-phase epitaxy approach meets spin coating method.

    KAUST Repository

    Chernikova, Valeriya

    2016-07-14

    Here we report a new and advanced method for the fabrication of highly oriented/polycrystalline metal-organic framework (MOF) thin films. Building on the attractive features of the liquid-phase epitaxy (LPE) approach, a facile spin coating method was implemented to generate MOF thin films in a high-throughput fashion. Advantageously, this approach offers a great prospective to cost-effectively construct thin-films with a significantly shortened preparation time and a lessened chemicals and solvents consumption, as compared to the conventional LPE-process. Certainly, this new spin-coating approach has been implemented successfully to construct various MOF thin films, ranging in thickness from a few micrometers down to the nanometer scale, spanning 2-D and 3-D benchmark MOF materials including Cu2(bdc)2•xH2O, Zn2(bdc)2•xH2O, HKUST-1 and ZIF-8. This method was appraised and proved effective on a variety of substrates comprising functionalized gold, silicon, glass, porous stainless steel and aluminum oxide. The facile, high-throughput and cost-effective nature of this approach, coupled with the successful thin film growth and substrate versatility, represents the next generation of methods for MOF thin film fabrication. Thereby paving the way for these unique MOF materials to address a wide range of challenges in the areas of sensing devices and membrane technology.

  9. Optical coherence tomography demonstrating macular retinal nerve fiber thinning in advanced optic disc drusen

    Directory of Open Access Journals (Sweden)

    Ali Hassan

    2014-01-01

    Full Text Available Optic disc drusen (ODD are extracellular proteinaceous excrescences in the optic nerve head. They enlarge over time and can cause damage to nerve fibers with resulting loss of visual field. The authors report a case of advanced ODD in which macular optical coherence tomography demonstrated retinal nerve fiber thinning. A single case report of a 42-year-old woman with known ODD presented to the eye clinic with worsening field of vision which was impacting on her daily life. The patient was subject to full ophthalmic examination as well as Goldmann visual field testing, optic disc photography and optical coherence tomography (OCT of both her optic discs and maculae. ODD although rare, can be visually devastating. No treatment is currently available however patients should be counseled about progressive nature of ODD and the potential for visual loss. OCT imaging of the maculae as well as optic discs may serve a role in monitoring the damage disc drusen cause to the eye.

  10. Optical coherence tomography demonstrating macular retinal nerve fiber thinning in advanced optic disc drusen.

    Science.gov (United States)

    Hassan, Ali; Gouws, Pieter

    2014-05-01

    Optic disc drusen (ODD) are extracellular proteinaceous excrescences in the optic nerve head. They enlarge over time and can cause damage to nerve fibers with resulting loss of visual field. The authors report a case of advanced ODD in which macular optical coherence tomography demonstrated retinal nerve fiber thinning. A single case report of a 42-year-old woman with known ODD presented to the eye clinic with worsening field of vision which was impacting on her daily life. The patient was subject to full ophthalmic examination as well as Goldmann visual field testing, optic disc photography and optical coherence tomography (OCT) of both her optic discs and maculae. ODD although rare, can be visually devastating. No treatment is currently available however patients should be counseled about progressive nature of ODD and the potential for visual loss. OCT imaging of the maculae as well as optic discs may serve a role in monitoring the damage disc drusen cause to the eye. PMID:25136235

  11. Optimization of the energy resolution and of the radioactive background rejection for ionization-heat detectors equipped with thermometric thin films for the direct WIMPs detection

    International Nuclear Information System (INIS)

    The EDELWEISS experiment aims at the direct detection of WIMPs as possible candidates for dark matter. It uses heat-and-ionization detectors that can discriminate these particles from the radioactive background. To date, this method is limited by events with incomplete charge collection that occur just beneath the detectors electrodes. In order to identify and reject these undesirable events, we have developed detectors equipped with thin films used both as thermometers - and hence sensitive to the transient athermal regime - and as electrodes for the charge collection. This thesis focuses on the optimization of such thin films regarding surface events rejection and on the modelling of the physical processes enabling this identification. The optimization must both maximize the fiducial volume and conserve an energy resolution such that the recoil energy threshold is of the order of 30 keV. Our work explores four generations of detectors each of which corresponds to successive evolutions in their conception. In all cases, the electrode-thermometer is an amorphous Anderson insulator NbSi thin film polarized by two interleaved comb-shaped niobium electrodes. In spite of constant progress in the successive detectors performances, the latest generation does not display the performances required for the EDELWEISS II experiment. Our work has shown the difficulty of the transient thermal signal modelling due to the complex contribution of the charge collection. This works has lead to new ideas regarding the detectors configuration, so that the athermal regime can be optimized to enhance both the rejection capability and the resolution. (author)

  12. High-resolution computed tomography for flaw detection in advanced thin-layer ceramics for fuel cells

    International Nuclear Information System (INIS)

    Advanced monolithic solid oxide fuel cells are being assembled from thin (∼50 μm) tape-cast ceramic layers with highly tailored mechanical properties. The layers need to be free of cracks and nonbonds. A high-resolution computed tomography system with a Ir-192 source was investigated as a tool for detecting cracks and nonbonds. Results suggest that channel sizes, including internal channels, can be determined but small in-plane cracks cannot be detected

  13. Antimicrobial activity of biopolymer–antibiotic thin films fabricated by advanced pulsed laser methods

    International Nuclear Information System (INIS)

    We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer–drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA–gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer–drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

  14. Antimicrobial activity of biopolymer–antibiotic thin films fabricated by advanced pulsed laser methods

    Energy Technology Data Exchange (ETDEWEB)

    Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, C.; Dorcioman, G.; Miroiu, F.M.; Socol, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Gittard, S.D.; Miller, P.R.; Narayan, R.J. [Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC 27599-7575 (United States); Enculescu, M. [National Institute for Materials Physics, PO Box MG-7, Bucharest-Magurele (Romania); Chrisey, D.B. [Tulane University, Department of Physics and Engineering Physics, New Orleans, LA (United States)

    2013-08-01

    We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer–drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA–gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer–drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

  15. The thin-film equation: recent advances and some new perspectives

    International Nuclear Information System (INIS)

    This paper is concerned with mathematical aspects of lubrication equations. In the first part, we discuss recent analytical achievements for various types of thin-film equations. Of interest are issues like (non-)uniqueness, wetting behaviour and contact line motion, in particular optimal propagation rates and waiting time or dead core phenomena. In the second part, we shall present novel numerical results for thin-film flow on heterogeneous substrates based on entropy consistent schemes. Finally, we will be concerned with new algorithmic concepts for the simulation of thin-film flow of shear-thinning liquids

  16. Advances on the compositional analysis of glycosphingolipids combining thin-layer chromatography with mass spectrometry.

    Science.gov (United States)

    Müthing, Johannes; Distler, Ute

    2010-01-01

    Glycosphingolipids (GSLs), composed of a hydrophilic carbohydrate chain and a lipophilic ceramide anchor, play pivotal roles in countless biological processes, including infectious diseases and the development of cancer. Knowledge of the number and sequence of monosaccharides and their anomeric configuration and linkage type, which make up the principal items of the glyco code of biologically active carbohydrate chains, is essential for exploring the function of GSLs. As part of the investigation of the vertebrate glycome, GSL analysis is undergoing rapid expansion owing to the application of novel biochemical and biophysical technologies. Mass spectrometry (MS) takes part in the network of collaborations to further unravel structural and functional aspects within the fascinating world of GSLs with the ultimate aim to better define their role in human health and disease. However, a single-method analytical MS technique without supporting tools is limited yielding only partial structural information. Because of its superior resolving power, robustness, and easy handling, high-performance thin-layer chromatography (TLC) is widely used as an invaluable tool in GSL analysis. The intention of this review is to give an insight into current advances obtained by coupling supplementary techniques such as TLC and mass spectrometry. A retrospective view of the development of this concept and the recent improvements by merging (1) TLC separation of GSLs, (2) their detection with oligosaccharide-specific proteins, and (3) in situ MS analysis of protein-detected GSLs directly on the TLC plate, are provided. The procedure works on a nanogram scale and was successfully applied to the identification of cancer-associated GSLs in several types of human tumors. The combination of these two supplementary techniques opens new doors by delivering specific structural information of trace quantities of GSLs with only limited investment in sample preparation. PMID:19609886

  17. Phase transformation in Ni-Mn-Sn ferromagnetic shape memory alloy thin films induced by dense ionization

    Energy Technology Data Exchange (ETDEWEB)

    Vishnoi, R.; Kaur, D. [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Laboratory, Department of Physics and Centre of Nanotechnology, Roorkee (India); Singhal, R.; Asokan, K.; Kanjilal, D. [Aruna Asaf Ali Marg, Inter University Accelerator Centre, New Delhi (India)

    2012-06-15

    The effects of 200 MeV Au ions irradiation on the structural and magnetic properties of Ni-Mn-Sn ferromagnetic shape memory alloy (FSMA) thin films have been systematically investigated. In order to understand the role of initial microstructure and phase of the film with respect to high energy irradiation, the two types of Ni-Mn-Sn FSMA films having different phases at room temperature were irradiated, one in martensite phase (Ni{sub 58.9}Mn{sub 28.0}Sn{sub 13.1}) and other in austenite phase (Ni{sub 50}Mn{sub 35.6}Sn{sub 14.4}). Transmission electron microscope (TEM) and scanning electron microscope (SEM) images along with the diffraction patterns of X-rays and electrons confirm that martensite phase transforms to austenite phase at a fluence of 6 x 10{sup 12} ions/cm{sup 2} and a complete amorphization occurs at a fluence of 3 x 10{sup 13} ions/cm{sup 2}, whereas ion irradiation has a minimal effect on the austenitic structure (Ni{sub 50}Mn{sub 35.6}Sn{sub 14.4}). Thermo-magnetic measurements also support the above mentioned behaviour of Ni-Mn-Sn FSMA films with increasing fluence of 200 MeV Au ions. The results are explained on the basis of thermal spike model considering the core and halo regions of ion tracks in FSMA materials. (orig.)

  18. A review on the understanding and fabrication advancement of MgB2 thin and thick films by HPCVD

    International Nuclear Information System (INIS)

    MgB2 thin films with superior superconducting properties are very promising for superconducting magnets, electronic devices and coated conductor electric power applications. A clear understanding of flux pinning mechanism in MgB2 films could be a big aid in improving the performance of MgB2 by the enhancement of Jc. The fabrication advancement and the understanding of flux pinning mechanism of MgB2 thin and thick films fabricated by using hybrid physical-chemical vapor deposition (HPCVD) are reviewed. The distinct kind of MgB2 films, such as single-crystal like MgB2 thin films, MgB2 epitaxial columnar thick films, and a-axis-oriented MgB2 films are included for flux pinning mechanism investigation. Various attempts made by researchers to improve further the flux pinning property and Jc performance by means of doping in MgB2 thin films by using HPCVD are also summarized

  19. Ionization state of ultra-thin carb on film irradiated by ultra-short intense laser pulse%超短超强激光脉冲辐照超薄碳膜电离状态研究∗

    Institute of Scientific and Technical Information of China (English)

    白春江; 崔万照; 余金清

    2016-01-01

    Ion acceleration is of interest for applications in fast ignition, compact particle sources, medical science, and others. The formation of plasma is of fundamental importance for understanding ion acceleration driven by intense laser. In order to further understand the solid dense material ionization dynamics under ultra-strong field, we use two-dimensional particle-in-cell code to study the ionization process of ultra-thin carbon film, driven by ultra-short intense laser pulse, particularly to see the plasma generation and distribution during the interaction. When an ultra-intense short pulse laser irradiates a solid dense nm-thick film target, the collisional ionization can be ignored for such a thin film target. If the target thickness is larger than laser pulse skin depth, the formation of plasma is contributed from laser field direct ionization and the ionization of electrostatic field inside the target, both of which are discussed and compared by the simulation results in this work. The ionization directly stimulated by laser field happens only near the laser-target interaction surface. After the generation of plasma on the target surface, electrons are accelerated into the target because of laser ponderomotive force. A huge electrostatic field is formed inside the target as a result of hot electron transport in it, and ionizes the target far from the interaction surface. It is found that a bigger fraction of ionization is contributed from electrostatic field ionization inside the target. The effect of laser pulse intensity on ionization is studied in detail, in which the laser pulse intensity is changed from 1 × 1018 W/cm2 to 1 × 1020 W/cm2. Comparing the results obtained under different intensities, we can see that higher intensity results in higher ionization speed, and much higher-order ions can be generated. At an intensity of 1 × 1020 W/cm2, although the intensity much higher than the threshold can generate C+6, only a small part of ions can be

  20. Ionization chamber

    International Nuclear Information System (INIS)

    An ionization chamber X-ray detector is described. It comprises a flat cathode sheet parallel to an anode which has a perforated insulating layer on its surface. An open grid, a thin perforated metal sheet is disposed on the insulating layer - the perforations of the layer and sheet are aligned. There is a detector gas and means for maintaining the grid at an electric potential between that of the anode and cathode and for measuring the current flow from the anode to the cathode. The grid shields the anode from the electric field produced by the positive ions which flow towards the cathode and this permits an independent measurement of the electron current flowing to the anode; even when the X-ray pulse length is not much shorter than the ion drift time. The recovery time of the ionization chamber is thus decreased by several orders of magnitude over previous chambers. The grid will normally be fixed to the anode and by shielding the anode from the cathode electric field, tends to eliminate capacitive microphone currents which would otherwise flow in the anode circuit. (U.K.)

  1. Guided ionization waves: Theory and experiments

    International Nuclear Information System (INIS)

    This review focuses on one of the fundamental phenomena that occur upon application of sufficiently strong electric fields to gases, namely the formation and propagation of ionization waves–streamers. The dynamics of streamers is controlled by strongly nonlinear coupling, in localized streamer tip regions, between enhanced (due to charge separation) electric field and ionization and transport of charged species in the enhanced field. Streamers appear in nature (as initial stages of sparks and lightning, as huge structures—sprites above thunderclouds), and are also found in numerous technological applications of electrical discharges. Here we discuss the fundamental physics of the guided streamer-like structures—plasma bullets which are produced in cold atmospheric-pressure plasma jets. Plasma bullets are guided ionization waves moving in a thin column of a jet of plasma forming gases (e.g., He or Ar) expanding into ambient air. In contrast to streamers in a free (unbounded) space that propagate in a stochastic manner and often branch, guided ionization waves are repetitive and highly-reproducible and propagate along the same path—the jet axis. This property of guided streamers, in comparison with streamers in a free space, enables many advanced time-resolved experimental studies of ionization waves with nanosecond precision. In particular, experimental studies on manipulation of streamers by external electric fields and streamer interactions are critically examined. This review also introduces the basic theories and recent advances on the experimental and computational studies of guided streamers, in particular related to the propagation dynamics of ionization waves and the various parameters of relevance to plasma streamers. This knowledge is very useful to optimize the efficacy of applications of plasma streamer discharges in various fields ranging from health care and medicine to materials science and nanotechnology

  2. Advances in the research of the role of Egr-1 gene in cells' response to ionizing radiation

    International Nuclear Information System (INIS)

    Egr-1 (early growth response-1) gene is an important member of the 'Immediate Early Growth' gene family, participating in multiple radiation biological effects of the irradiated cells. Studies have shown that after ionizing radiation, Egr-1 gene can be activated at an early stage in many types of tumor and normal cells. Its activation and the consequent expression is believed to have a close relation to the change in cell growth, cell cycle and apoptosis of the irradiated cells. Additionally, the radiation-inducible property of the Egr-1 gene regulating sequence confers potential clinical and genetic engineering uses

  3. Recent advances in the transparent conducting ZnO for thin-film Si solar cells

    Science.gov (United States)

    Moon, Taeho; Shin, Gwang Su; Park, Byungwoo

    2015-11-01

    The key challenge for solar-cell development lies in the improvement of power-conversion efficiency and the reduction of fabrication cost. For thin-film Si solar cells, researches have been especially focused on the light trapping for the breakthrough in the saturated efficiencies. The ZnO-based transparent conducting oxides (TCOs) have therefore received strong attention because of their excellent light-scattering capability by the texture-etched surface and cost effectiveness through in-house fabrication. Here, we have highlighted our recent studies on the transparent conducting ZnO for thin-film Si solar cells. From the electrical properties and their degradation mechanisms, bilayer deposition and organic-acid texturing approaches for enhancing the light trapping, and finally the relation between textured ZnO and electrical cell performances are sequentially introduced in this review article. [Figure not available: see fulltext.

  4. Simulation of Thin-Film Damping and Thermal Mechanical Noise Spectra for Advanced Micromachined Microphone Structures

    OpenAIRE

    Hall, Neal A.; Okandan, Murat; Littrell, Robert; Bicen, Baris; Degertekin, F. Levent

    2008-01-01

    In many micromachined sensors the thin (2–10 μm thick) air film between a compliant diaphragm and backplate electrode plays a dominant role in shaping both the dynamic and thermal noise characteristics of the device. Silicon microphone structures used in grating-based optical-interference microphones have recently been introduced that employ backplates with minimal area to achieve low damping and low thermal noise levels. Finite-element based modeling procedures based on 2-D discretization of...

  5. Deposition of thin titanium-copper films with antimicrobial effect by advanced magnetron sputtering methods

    International Nuclear Information System (INIS)

    The antibacterial effect of thin titanium-copper (Ti-Cu) films combined with sufficient growth of human osteoblastic cells is reported in the paper. Thin Ti-Cu films were prepared by three different plasma-assisted magnetron sputtering methods: direct current magnetron sputtering (dc-MS), dual magnetron sputtering (dual-MS) as well as dual high power impulse magnetron sputtering (dual-HiPIMS). The antimicrobial effect is caused by copper released from the metallic Ti-Cu films, which was measured by atomic absorption spectroscopy (AAS). The copper release is influenced by the chemical and physical properties of the deposited films and was investigated by X-ray diffractometry and X-ray reflectometry (GIXD and XR) techniques. It was found that, within the first 24 h the amount of Cu released from dual-HiPIMS films (about 250 μg) was much higher than from dc-MS and dual-MS films. In vitro planktonic growth tests on Ti-Cu surfaces for Staphylococcus epidermidis and S. aureus demonstrated the killing of both bacteria using the Ti-Cu films prepared using the dual-HiPIMS technique. The killing effects on biofilm bacteria were less obvious. After the total release of copper from the Ti-Cu film the vitality of exposed human osteoblast MG-63 cells increased significantly. An initial cytotoxic effect followed by the growth of osteoblastic cells was demonstrated. The cytotoxic effect combined with growth of osteoblastic cells could be used in joint replacement surgery to reduce the possibility of infection and to increase adoption of the implants. Highlights: → Ti-Cu films with significant cytotoxic effect were prepared by dual-HiPIMS technique. → The cytotoxic effect is caused by total release of copper species from thin films. → The copper release is influenced by crystallography and chemical properties of thin films. → Sufficient growth of osteoblastic cells follows after copper release.

  6. Advances in Thin-Film Si Solar Cells by Means of SiOx Alloys

    OpenAIRE

    Lucia V. Mercaldo; Iurie Usatii; Paola Delli Veneri

    2016-01-01

    The conversion efficiency of thin-film silicon solar cells needs to be improved to be competitive with respect to other technologies. For a more efficient use of light across the solar spectrum, multi-junction architectures are being considered. Light-management considerations are also crucial in order to maximize light absorption in the active regions with a minimum of parasitic optical losses in the supportive layers. Intrinsic and doped silicon oxide alloys can be advantageously applied wi...

  7. Advances in CuInSe sub 2 and CdTe thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shafarmann, W.N.; Birkmire, R.W.; Farding, D.A.; McCandless, B.E.; Mondal, A.; Phillips, J.E.; Varrin, R.D. Jr. (Delaware Univ., Newark (USA). Inst. of Energy Conversion)

    1991-05-01

    Research on CuInSe{sub 2} and CdTe thin film solar cells is discussed. CuInSe{sub 2} was deposited by selenization of Cu/In layers and was used to make a 10% efficient CuInSe{sub 2}/(CdZn)S cell. Characterization of the reaction mechanisms is described. The open-circuit voltage V{sub oc} of CuInSe{sub 2}/(CdZn)S cells is dominated by recombination in the space charge region, so increassing the band gap or decreasing the width of this region should increase V{sub oc}. Increasing the band gap with a thin Cu(InGa)Se{sub 2} layer at the CuInSe{sub 2} surface has demonstrated increased V{sub oc} with collection out to the CuInSe{sub 2} band gap. A post-deposition treatment and contacting process for evaporated CdS/CdTe cells was developed and high efficiency cells were made. Several steps in the process, including a CdCl{sub 2} coating, a 400deg C heat treatment, and a contact containing copper are critical. ZnTe films were deposited from an aqueous solution as a contact to CdTe. (orig.).

  8. Advances in Thin-Film Si Solar Cells by Means of SiOx Alloys

    Directory of Open Access Journals (Sweden)

    Lucia V. Mercaldo

    2016-03-01

    Full Text Available The conversion efficiency of thin-film silicon solar cells needs to be improved to be competitive with respect to other technologies. For a more efficient use of light across the solar spectrum, multi-junction architectures are being considered. Light-management considerations are also crucial in order to maximize light absorption in the active regions with a minimum of parasitic optical losses in the supportive layers. Intrinsic and doped silicon oxide alloys can be advantageously applied within thin-film Si solar cells for these purposes. Intrinsic a-SiOx:H films have been fabricated and characterized as a promising wide gap absorber for application in triple-junction solar cells. Single-junction test devices with open circuit voltage up to 950 mV and ~1 V have been demonstrated, in case of rough and flat front electrodes, respectively. Doped silicon oxide alloys with mixed-phase structure have been developed, characterized by considerably lower absorption and refractive index with respect to standard Si-based films, accompanied by electrical conductivity above 10−5 S/cm. These layers have been successfully applied both into single-junction and micromorph tandem solar cells as superior doped layers with additional functionalities.

  9. Tungsten oxide (WO3) thin films for application in advanced energy systems

    International Nuclear Information System (INIS)

    Inherent processes in coal gasification plants produce hazardous hydrogen sulfide (H2S), which must be continuously and efficiently detected and removed before the fuel is used for power generation. An attempt has been made in this work to fabricate tungsten oxide (WO3) thin films by radio-frequency reactive magnetron-sputter deposition. The impetus being the use of WO3 films for H2S sensors in coal gasification plants. The effect of growth temperature, which is varied in the range of 30-500 deg. C, on the growth and microstructure of WO3 thin films is investigated. Characterizations made using scanning electron microscopy (SEM) and x-ray diffraction (XRD) indicate that the effect of temperature is significant on the microstructure of WO3 films. XRD and SEM results indicate that the WO3 films grown at room temperature are amorphous, whereas films grown at higher temperatures are nanocrystalline. The average grain-size increases with increasing temperature. WO3 films exhibit smooth morphology at growth temperatures ≤300 deg. C while relatively rough at >300 deg. C. The analyses indicate that the nanocrystalline WO3 films grown at 100-300 deg. C could be the potential candidates for H2S sensor development for application in coal gasification systems.

  10. Nutritional supplement during the treatment with ionizing radiations in patients with head and neck tumors in advanced stages

    International Nuclear Information System (INIS)

    Malnutrition in the patient with advanced cancer favors immunosuppression and implies a low Karnofsky index, poor tolerance and response to the onco specific curative or palliative treatments, high susceptibility to infections and, as a result, a decline of the quality of life. Patients with head and neck tumors in advanced stages (III-IV) are one of the groups of high risk for malnutrition due to the reduction of the intake of nutrients, anorexia, alterations of the deglutition mechanism, and mechanical obstruction of the upper digestive tract, among other causes.Numerous studies show the convenience of the nutritional supplement in these patients during the onco specific treatment. A prospective study that included 15 patients with head and neck neoplasia in advanced stages, and with clinical signs of malnutrition, was conducted in order to evaluate the necessary calorie-energy supplement. All of them were administered an oral nutritional supplement (Adn-22 %) during the radiation treatment to assess the possibility of improving their tolerance and response to the treatment. Of the 15 studied cases, 13 presented complications in connection with the treatment, but most them were mild, and they did not affect in a significant way the time of duration and the total dose of treatment. There was a favorable response in relation to the tumor

  11. Thin film silicon solar cells: advanced processing and characterization - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ballif, Ch.

    2008-04-15

    This final report elaborated for the Swiss Federal Office of Energy (SFOE) takes a look at the results of a project carried out at the photovoltaics laboratory at the University of Neuchatel in Switzerland. The project aimed to demonstrate the production of high-efficiency thin-film silicon devices on flexible substrates using low cost processes. New ways of improving processing and characterisation are examined. The process and manufacturing know-how necessary to provide support for industrial partners within the framework of further projects is discussed. The authors state that the efficiency of most devices was significantly improved, both on glass substrates and on flexible plastic foils. The process reproducibility was also improved and the interactions between the different layers in the device are now said to be better understood. The report presents the results obtained and discusses substrate materials, transparent conductors, defect analyses and new characterisation tools. Finally, the laboratory infrastructure is described.

  12. Modified Separator Using Thin Carbon Layer Obtained from Its Cathode for Advanced Lithium Sulfur Batteries.

    Science.gov (United States)

    Liu, Naiqiang; Huang, Bicheng; Wang, Weikun; Shao, Hongyuan; Li, Chengming; Zhang, Hao; Wang, Anbang; Yuan, Keguo; Huang, Yaqin

    2016-06-29

    The realization of a practical lithium sulfur battery system, despite its high theoretical specific capacity, is severely limited by fast capacity decay, which is mainly attributed to polysulfide dissolution and shuttle effect. To address this issue, we designed a thin cathode inactive material interlayer modified separator to block polysulfides. There are two advantages for this strategy. First, the coating material totally comes from the cathode, thus avoids the additional weights involved. Second, the cathode inactive material modified separator improve the reversible capacity and cycle performance by combining gelatin to chemically bond polysulfides and the carbon layer to physically block polysulfides. The research results confirm that with the cathode inactive material modified separator, the batteries retain a reversible capacity of 644 mAh g(-1) after 150 cycles, showing a low capacity decay of about 0.11% per circle at the rate of 0.5C. PMID:27267483

  13. Radiation dependent ionization model

    International Nuclear Information System (INIS)

    For laser created plasma simulation, hydrodynamics codes need a non-LTE atomic physics package for both EOS and optical properties (emissivity and opacity). However in XRL targets as in some ICF targets, high Z material can be found. In these cases radiation trapping can induce a significant departure from the optically thin ionization description. The authors present a method to change an existing LTE code into a non-LTE code with coupling of ionization to radiation. This method has very low CPU cost and can be used in 2D simulations

  14. Advances in thin film diffraction instrumentation by X-ray optics

    Energy Technology Data Exchange (ETDEWEB)

    Haase, A. [Rich. Seifert and Co., Analytical X-ray Systems, Ahrensburg (Germany)

    1996-09-01

    The structural characterisation of thin films requires a parallel X-ray beam of high intensity. Parallel beam geometry is commonly used in high resolution and single crystal experiments, but also in the field of X-ray diffraction for polycrystalline material (e.g. in phase, texture and stress analysis). For grazing incidence diffraction (GID), the use of small slits on the primary side and of long soller slits with a flat monochromator on the secondary side is standard. New optical elements have been introduced with polychromatic or monochromatic radiation. By means of different applications the results are compared with those of classical beam optics. X-ray fiber optics utilize total external reflection of X-rays on smooth surfaces. Effects of monochromatization are presented. In many fields of application, fiber optics may replace conventional collimators. The use of primary and secondary channel cut crystals can also produce a high parallel monochromatic X-ray beam. A parabolically bent graded multilayer produces a monochromatic parallel beam of high intensity. Compared with classical Bragg-Brentano (focussing) geometry, excellent results have been obtained, especially for samples with an irregular shape. In combination with a channel cut monochromator there is a substantial gain in intensity leading to an increase of the dynamic intensity range of rocking curves.

  15. Evaluation of advanced automatic PET segmentation methods using nonspherical thin-wall inserts

    Energy Technology Data Exchange (ETDEWEB)

    Berthon, B., E-mail: BerthonB@cardiff.ac.uk; Marshall, C. [Wales Research and Diagnostic Positron Emission Tomography Imaging Centre, Cardiff CF14 4XN (United Kingdom); Evans, M. [Velindre Cancer Centre, Cardiff CF14 2TL (United Kingdom); Spezi, E. [Department of Medical Physics, Velindre Cancer Centre, Cardiff CF14 2TL (United Kingdom)

    2014-02-15

    Purpose: The use of positron emission tomography (PET) within radiotherapy treatment planning requires the availability of reliable and accurate segmentation tools. PET automatic segmentation (PET-AS) methods have been recommended for the delineation of tumors, but there is still a lack of thorough validation and cross-comparison of such methods using clinically relevant data. In particular, studies validating PET segmentation tools mainly use phantoms with thick plastic walls inserts of simple spherical geometry and have not specifically investigated the effect of the target object geometry on the delineation accuracy. Our work therefore aimed at generating clinically realistic data using nonspherical thin-wall plastic inserts, for the evaluation and comparison of a set of eight promising PET-AS approaches. Methods: Sixteen nonspherical inserts were manufactured with a plastic wall of 0.18 mm and scanned within a custom plastic phantom. These included ellipsoids and toroids derived with different volumes, as well as tubes, pear- and drop-shaped inserts with different aspect ratios. A set of six spheres of volumes ranging from 0.5 to 102 ml was used for a baseline study. A selection of eight PET-AS methods, written in house, was applied to the images obtained. The methods represented promising segmentation approaches such as adaptive iterative thresholding, region-growing, clustering and gradient-based schemes. The delineation accuracy was measured in terms of overlap with the computed tomography reference contour, using the dice similarity coefficient (DSC), and error in dimensions. Results: The delineation accuracy was lower for nonspherical inserts than for spheres of the same volume in 88% cases. Slice-by-slice gradient-based methods, showed particularly lower DSC for tori (DSC < 0.5), caused by a failure to recover the object geometry. The region-growing method reached high levels of accuracy for most inserts (DSC > 0.76 except for tori) but showed the largest

  16. Evaluation of advanced automatic PET segmentation methods using nonspherical thin-wall inserts

    International Nuclear Information System (INIS)

    Purpose: The use of positron emission tomography (PET) within radiotherapy treatment planning requires the availability of reliable and accurate segmentation tools. PET automatic segmentation (PET-AS) methods have been recommended for the delineation of tumors, but there is still a lack of thorough validation and cross-comparison of such methods using clinically relevant data. In particular, studies validating PET segmentation tools mainly use phantoms with thick plastic walls inserts of simple spherical geometry and have not specifically investigated the effect of the target object geometry on the delineation accuracy. Our work therefore aimed at generating clinically realistic data using nonspherical thin-wall plastic inserts, for the evaluation and comparison of a set of eight promising PET-AS approaches. Methods: Sixteen nonspherical inserts were manufactured with a plastic wall of 0.18 mm and scanned within a custom plastic phantom. These included ellipsoids and toroids derived with different volumes, as well as tubes, pear- and drop-shaped inserts with different aspect ratios. A set of six spheres of volumes ranging from 0.5 to 102 ml was used for a baseline study. A selection of eight PET-AS methods, written in house, was applied to the images obtained. The methods represented promising segmentation approaches such as adaptive iterative thresholding, region-growing, clustering and gradient-based schemes. The delineation accuracy was measured in terms of overlap with the computed tomography reference contour, using the dice similarity coefficient (DSC), and error in dimensions. Results: The delineation accuracy was lower for nonspherical inserts than for spheres of the same volume in 88% cases. Slice-by-slice gradient-based methods, showed particularly lower DSC for tori (DSC 0.76 except for tori) but showed the largest errors in the recovery of pears and drops dimensions (higher than 10% and 30% of the true length, respectively). Large errors were visible

  17. Recent advances in the growth, doping and characterization of III V nitride thin films

    Science.gov (United States)

    Davis, Robert F.; Ailey, K. S.; Bremser, M. D.; Carlson, E.; Kern, R. S.; Kester, D. J.; Perry, W. G.; Tanaka, S.; Weeks, T. W.

    Boron nitride thin films have been grown on the (100) surfaces of Si and diamond via ion beam assisted deposition (IBAD) using electron beam evaporation of B in tandem with N and Ar ion bombardment within the ranges of substrate temperature and ion flux of 200-700°C and 0.20-0.30 mA/cm2, respectively. Fourier-transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM) revealed a growth sequence of amorphous (a-BN), hexagonal (h-BN) and cubic (c-BN) layers under most conditions. This sequence is attributed primarily to increasing biaxial compressive stress with film thickness due to ion bombardment and some interstitial Ar incorporation. A minimum substrate temperature of 200-300° C is required for nucleation and growth of single phase c-BN by this technique. The initial stage of AlN film growth on α(6H)-SiC(0001) substrates by plasma-assisted, gas source molecular beam epitaxy has been investigated in terms of growth mode and interface defects. Essentially atomically flat AlN surfaces, indicative of two-dimensional growth, were obtained using on-axis substrates. Island-like features were observed on the vicinal surfaces. The coalescence of latter features gave rise to double positioning boundaries as a result of the misalignment of the Si/C bilayer steps with the Al/N bilayers in the growing films. The quality of the thicker AlN films was strongly influenced by the concentration of these boundaries. Monocrystalline GaN and AlxGa1-x N(0001) (0≤x≤1) films, void of oriented domain structures and associated low-angle grain boundaries and with smooth surface morphologies, have been grown via OMVPE on high-temperature monocrystalline AlN(0001) buffer layers, previously deposited on vicinal α(6H)-SiC(0001) wafers, using TEG, TEA and ammonia in a cold-wall, vertical, pancake-style reactor. Abrupt heterojunctions were demonstrated. The PL spectrum of the pure GaN showed strong near band-edge emissions with a FWHM value of 4 me

  18. Photoluminescence of radiation-induced color centers in lithium fluoride thin films for advanced diagnostics of proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Piccinini, M., E-mail: massimo.piccinini@enea.it; Ampollini, A.; Picardi, L.; Ronsivalle, C.; Bonfigli, F.; Libera, S.; Vincenti, M. A.; Montereali, R. M. [ENEA, C.R. Frascati, UTAPRAD, Technical Unit for Development and Applications of Radiations, Via E. Fermi 45, 00044 Frascati (Rome) (Italy); Ambrosini, F. [University Sapienza-Roma I, Piazzale Aldo Moro 5, 00185 Rome (Italy); Nichelatti, E. [ENEA, C.R. Casaccia, UTTMAT, Technical Unit for Materials Technologies, Via Anguillarese 301, 00123 S. Maria di Galeria (Rome) (Italy)

    2015-06-29

    Systematic irradiation of thermally evaporated 0.8 μm thick polycrystalline lithium fluoride films on glass was performed by proton beams of 3 and 7 MeV energies, produced by a linear accelerator, in a fluence range from 10{sup 11} to 10{sup 15} protons/cm{sup 2}. The visible photoluminescence spectra of radiation-induced F{sub 2} and F{sub 3}{sup +} laser active color centers, which possess almost overlapping absorption bands at about 450 nm, were measured under laser pumping at 458 nm. On the basis of simulations of the linear energy transfer with proton penetration depth in LiF, it was possible to obtain the behavior of the measured integrated photoluminescence intensity of proton irradiated LiF films as a function of the deposited dose. The photoluminescence signal is linearly dependent on the deposited dose in the interval from 10{sup 3} to about 10{sup 6 }Gy, independently from the used proton energies. This behavior is very encouraging for the development of advanced solid state radiation detectors based on optically transparent LiF thin films for proton beam diagnostics and two-dimensional dose mapping.

  19. Photoluminescence of radiation-induced color centers in lithium fluoride thin films for advanced diagnostics of proton beams

    International Nuclear Information System (INIS)

    Systematic irradiation of thermally evaporated 0.8 μm thick polycrystalline lithium fluoride films on glass was performed by proton beams of 3 and 7 MeV energies, produced by a linear accelerator, in a fluence range from 1011 to 1015 protons/cm2. The visible photoluminescence spectra of radiation-induced F2 and F3+ laser active color centers, which possess almost overlapping absorption bands at about 450 nm, were measured under laser pumping at 458 nm. On the basis of simulations of the linear energy transfer with proton penetration depth in LiF, it was possible to obtain the behavior of the measured integrated photoluminescence intensity of proton irradiated LiF films as a function of the deposited dose. The photoluminescence signal is linearly dependent on the deposited dose in the interval from 103 to about 106 Gy, independently from the used proton energies. This behavior is very encouraging for the development of advanced solid state radiation detectors based on optically transparent LiF thin films for proton beam diagnostics and two-dimensional dose mapping

  20. Thin film subsurface environments; Advanced X-ray spectroscopies and a novel Bayesian inference modeling algorithm

    Science.gov (United States)

    Church, Jonathan R.

    New condensed matter metrologies are being used to probe ever smaller length scales. In support of the diverse field of materials research synchrotron based spectroscopies provide sub-micron spatial resolutions and a breadth of photon wavelengths for scientific studies. For electronic materials the thinnest layers in a complementary metal-oxide-semiconductor (CMOS) device have been reduced to just a few nanometers. This raises concerns for layer uniformity, complete surface coverage, and interfacial quality. Deposition processes like chemical vapor deposition (CVD) and atomic layer deposition (ALD) have been shown to deposit the needed high-quality films for the requisite thicknesses. However, new materials beget new chemistries and, unfortunately, unwanted side-reactions and by-products. CVD/ALD tools and chemical precursors provided by our collaborators at Air Liquide utilized these new chemistries and films were deposited for which novel spectroscopic characterization methods were used. The second portion of the thesis focuses on fading and decomposing paint pigments in iconic artworks. Efforts have been directed towards understanding the micro-environments causing degradation. Hard X-ray photoelectron spectroscopy (HAXPES) and variable kinetic energy X-ray photoelectron spectroscopy (VKE-XPS) are advanced XPS techniques capable of elucidating both chemical environments and electronic band structures in sub-surface regions of electronic materials. HAXPES has been used to study the electronic band structure in a typical CMOS structure; it will be shown that unexpected band alignments are associated with the presence of electronic charges near a buried interface. Additionally, a computational modeling algorithm, Bayes-Sim, was developed to reconstruct compositional depth profiles (CDP) using VKE-XPS data sets; a subset algorithm also reconstructs CDP from angle-resolved XPS data. Reconstructed CDP produced by Bayes-Sim were most strongly correlated to the real

  1. Optical Thin Films for Gas Sensing in Advanced Coal Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ohodnicki, Paul; Brown, Thomas; Baltrus John; Chorpening, Benjamin

    2012-08-09

    Even for existing coal based plants, the opportunity for sensors and controls to improve efficiency is great. A wide range of gas species are of interest for relevant applications. Functional sensor layers for embedded sensing must be compatible with extreme conditions (temperature, pressure, corrosive). Au incorporated metal oxides have been looked at by a number of other authors previously for gas sensing, but have often focused on temperatures below 500{degree}C. Au nanoparticle incorporated metal oxide thin films have shown enhanced gas sensing response. In prior work, we have demonstrated that material systems such as Au nanoparticle incorporated TiO{sub 2} films exhibit a potentially useful optical response to changing gas atmospheres at temperatures up to ~800-850{degree}C. Current work is focused on sputter-deposited Au/TiO{sub 2} films. Au and Ti are multi-layered sputter deposited, followed by a 950{degree}C oxidation step. Increasing Au layer thickness yields larger particles. Interband electronic transitions significantly modify the optical constants of Au as compared to the damped free electron theory. A high temperature oxidation (20%O{sub 2}/N{sub 2}) treatment was performed at 700{degree}C followed by a reduction (4%H{sub 2}/N{sub 2}) treatment to illustrate the shift in both absorption and scattering with exposure to reducing gases. Shift of localized surface plasmon resonance (LSPR) absorption peak in changing gas atmospheres is well documented, but shift in the peak associated with diffuse scattering is a new observation. Increasing Au layer-thickness results in an increase in LSPR absorption and a shift to longer wavelengths. Diffuse scattering associated with the LSPR resonance of Au shows a similar trend with increasing Au thickness. To model the temperature dependence of LSPR, the modification to the plasmon frequency, the damping frequency, and the dielectric constant of the oxide matrix must be accounted for. Thermal expansion of Au causes

  2. Ionization detector

    International Nuclear Information System (INIS)

    A novel ionization detector for use in X-ray tomography is described in detail. To achieve the ultimate resolution, the use of small detectors is necessary and, for ionization detectors, this implies using xenon gas at high pressure. Conventional small detectors can suffer from ''bowing'' but the present design overcomes their problems. (U.K.)

  3. Transient terahertz photoconductivity measurements of minority-carrier lifetime in tin sulfide thin films: Advanced metrology for an early-stage photovoltaic material

    OpenAIRE

    Jaramillo, R.; Sher, Meng-Ju; Ofori-Okai, Benjamin K.; Steinmann, V; Yang, Chuanxi; Hartman, Katy; Nelson, Keith A.; Lindenberg, Aaron M.; Gordon, Roy G.; Buonassisi, T.

    2015-01-01

    Materials research with a focus on enhancing the minority-carrier lifetime of the light-absorbing semiconductor is key to advancing solar energy technology for both early-stage and mature material platforms alike. Tin sulfide (SnS) is an absorber material with several clear advantages for manufacturing and deployment, but the record power conversion efficiency remains below 5%. We report measurements of bulk and interface minority-carrier recombination rates in SnS thin films using optical-pu...

  4. Ionization detector

    International Nuclear Information System (INIS)

    The objects of the invention are, first, to provide an ionization detector having a three chamber structure characterised by a built-in feedback path that regeneratively stabilizes the operating point of the detector. Secondly, to provide a specially designed chamber construction including electrodes shaped so as to enhance the efficiency of the chamber and reduce ion recombination. The ionization chamber described has a chamber structure with a first closed chamber and a second chamber able to receive gases from outside. These two chambers have a common boundary including a common electrode. One electrode associated with the second chamber, and one within the first chamber, define a third chamber within the first chamber allowing an ionization path between. A radioactive source provides ionizing radiation for all three chambers and establishes an ionization current. There is a detector coupled to the common electrode for detecting changes in this current. (U.K.)

  5. IRAS 13197-1627 has them all: Compton-thin absorption, photo-ionized gas, thermal plasmas, and a broad Fe line

    OpenAIRE

    G. Miniutti(Centro de Astrobiologia); Ponti, G; Dadina, M.; Cappi, M.; Malaguti, G.

    2006-01-01

    We report results from the XMM-Newton observation of IRAS 13197-1627, a luminous IR galaxy with a Seyfert 1.8 nucleus. The hard X-ray spectrum is steep and is absorbed by Compton-thin neutral gas. We detect an Fe emission line at 6.4 keV, consistent with transmission through the absorber. The most striking result of our spectral analysis is the detection of a dominant X-ray reflection component and broad Fe line from the inner accretion disc. The reflection-dominated hard X-ray spectrum is co...

  6. Ionization detector

    International Nuclear Information System (INIS)

    An ionization detecting fire alarm device that comprises a double chamber structure, a source disposed in at least one of the chambers and a vernier adjusting screw electrode protruding into one chamber is described. The chamber containing the adjustable electrode is more open to the atmosphere than the other chamber, porting is provided between chambers and detection occurs by sensing the rate of change of ionization current in the chamber structure. The source or sources, one being in each chamber, is a beta source such as a nickel 63 source. A change in ionization current is detected by a unique circuit of this invention which comprises a programmable unijunction transistor oscillator circuit. 19 claims, 4 figures

  7. Monitoring of monooctanoyl phosphatidylcholine synthesis by enzymatic acidolysis between soybean phosphatidylcholine and caprylic acid by thin-layer chromatography with a flame ionization detector

    DEFF Research Database (Denmark)

    Vikbjerg, Anders Falk; Mu, Huiling; Xu, Xuebing

    2005-01-01

    dosage, reaction temperature, solvent amount, reaction time, and substrate ratio (mol/mol caprylic acid/PC) on formation of ML-type PC in batch reactor with Thermomyces lanuginosa lipase as the catalyst. The formation of ML-type PC was dependent on all parameters examined except for substrate ratio. ML......-type PC content increased with increasing enzyme dosage, reaction temperature, solvent amount, and reaction time. Substrate ratio had no significant effect on the formation of ML-type PC within the tested range (3-15 mol/mol). The formation of MM-type PC was observed in some experiments, indicating that...... was found that the structured PC fractionated into 2-3 distinct bands on both plate thin layer chromatography (TLC) and Chromarod TLC. These 3 bands represented PC of LL-type, ML-type and MM-type, respectively. The TLC-FID method was applied in the present study to examine the influence of enzyme...

  8. Ionizing radiations

    International Nuclear Information System (INIS)

    The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)

  9. III. Penning ionization, associative ionization and chemi-ionization processes

    International Nuclear Information System (INIS)

    Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

  10. Thin film deposition at atmospheric pressure using dielectric barrier discharges: Advances on three-dimensional porous substrates and functional coatings

    Science.gov (United States)

    Fanelli, Fiorenza; Bosso, Piera; Mastrangelo, Anna Maria; Fracassi, Francesco

    2016-07-01

    Surface processing of materials by atmospheric pressure dielectric barrier discharges (DBDs) has experienced significant growth in recent years. Considerable research efforts have been directed for instance to develop a large variety of processes which exploit different DBD electrode geometries for the direct and remote deposition of thin films from precursors in gas, vapor and aerosol form. This article briefly reviews our recent progress in thin film deposition by DBDs with particular focus on process optimization. The following examples are provided: (i) the plasma-enhanced chemical vapor deposition of thin films on an open-cell foam accomplished by igniting the DBD throughout the entire three-dimensional (3D) porous structure of the substrate, (ii) the preparation of hybrid organic/inorganic nanocomposite coatings using an aerosol-assisted process, (iii) the DBD jet deposition of coatings containing carboxylic acid groups and the improvement of their chemical and morphological stability upon immersion in water.

  11. Ionizing radiation

    International Nuclear Information System (INIS)

    The subject is discussed under the headings: characteristics of ionizing radiations; biological effects; comparison of radiation and other industrial risks; principles of protection; cost-benefit analysis; dose limits; the control and monitoring of radiation; reference levels; emergency reference levels. (U.K.)

  12. IRAS 13197-1627 has them all: Compton-thin absorption, photo-ionized gas, thermal plasmas, and a broad Fe line

    CERN Document Server

    Miniutti, G; Dadina, M; Cappi, M; Malaguti, G

    2006-01-01

    We report results from the XMM-Newton observation of IRAS 13197-1627, a luminous IR galaxy with a Seyfert 1.8 nucleus. The hard X-ray spectrum is steep and is absorbed by Compton-thin neutral gas. We detect an Fe emission line at 6.4 keV, consistent with transmission through the absorber. The most striking result of our spectral analysis is the detection of a dominant X-ray reflection component and broad Fe line from the inner accretion disc. The reflection-dominated hard X-ray spectrum is confirmed by the strong Compton hump seen in a previous BeppoSAX observation and could be the sign that most of the primary X-rays are radiated from a compact corona (or e.g. base of the jet) within a few gravitational radii from the black hole. We also detect a relatively strong absorption line at 6.81 keV which, if interpreted as Fe xxv resonant absorption intrinsic to the source, implies an outflow with velocity of about 5000 km/s. In the soft energy band, the high-resolution RGS and the CCD-resolution data show the pres...

  13. Fabrication of near-field optical probes using advanced functional thin films for MEMS and NEMS applications

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, J.S.; Moon, J.-S.; Park, J.-H.; Kim, J.W.; Kim, Y.D. [Department of Chemistry and Center for Advanced Plasma Surface Technology, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Boo, J.-H. [Department of Chemistry and Center for Advanced Plasma Surface Technology, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)], E-mail: jhboo@skku.edu

    2008-04-15

    Highly efficient atomic force microscopy (AFM) cantilevers and an near-field scanning optical microscopy (NSOM) aperture array were fabricated using the functional Si{sub 3}N{sub 4} and SiO{sub 2} thin films for the micro electro mechanical systems (MEMS) and NEMS applications. In order to generate the cantilevers and array, a silicon nitride (Si{sub 3}N{sub 4}) thin film with a stress below 100 MPa was deposited using NH{sub 3} and SiCl{sub 2}H{sub 2} gases with a relative ratio of 1:5 at 140 mTorr, and 835 deg. C by low pressure chemical vapor deposition (LPCVD). Cantilevers of 10-100 {mu}m in length were fabricated with Si{sub 3}N{sub 4} thin films. Photolithography and magnetically enhanced reactive ion etching (MERIE) techniques were employed for patterning the Si{sub 3}N{sub 4} thin films and selective bulk etching of Si was carried out using a strong alkaline solution of tetramethylammoniumhyroxide (TMAH) to generate the Si{sub 3}N{sub 4}-based cantilevers with 3D shapes. In addition, we also successfully fabricated an array of SiO{sub 2} apertures with sub-wavelength sizes as near-field optical probe in order to examine the possible light resonance-tunneling phenomenon. Initially, a (50 x 50) array with a dimension of (5 mm x 5 mm) was fabricated on a Si wafer followed by the V-groove formation using alkaline solution Si bulk micromachining technology. The size of the aperture on top of the pyramidal array was carefully controlled with an opening rate of {approx}27 nm/min using HF solution diluted by a factor of 50 using water. The Al thin film was thermally evaporated on the (50 x 50) array pattern for the fabrication of apertures with sub-wavelength sizes.

  14. Fabrication of near-field optical probes using advanced functional thin films for MEMS and NEMS applications

    International Nuclear Information System (INIS)

    Highly efficient atomic force microscopy (AFM) cantilevers and an near-field scanning optical microscopy (NSOM) aperture array were fabricated using the functional Si3N4 and SiO2 thin films for the micro electro mechanical systems (MEMS) and NEMS applications. In order to generate the cantilevers and array, a silicon nitride (Si3N4) thin film with a stress below 100 MPa was deposited using NH3 and SiCl2H2 gases with a relative ratio of 1:5 at 140 mTorr, and 835 deg. C by low pressure chemical vapor deposition (LPCVD). Cantilevers of 10-100 μm in length were fabricated with Si3N4 thin films. Photolithography and magnetically enhanced reactive ion etching (MERIE) techniques were employed for patterning the Si3N4 thin films and selective bulk etching of Si was carried out using a strong alkaline solution of tetramethylammoniumhyroxide (TMAH) to generate the Si3N4-based cantilevers with 3D shapes. In addition, we also successfully fabricated an array of SiO2 apertures with sub-wavelength sizes as near-field optical probe in order to examine the possible light resonance-tunneling phenomenon. Initially, a (50 x 50) array with a dimension of (5 mm x 5 mm) was fabricated on a Si wafer followed by the V-groove formation using alkaline solution Si bulk micromachining technology. The size of the aperture on top of the pyramidal array was carefully controlled with an opening rate of ∼27 nm/min using HF solution diluted by a factor of 50 using water. The Al thin film was thermally evaporated on the (50 x 50) array pattern for the fabrication of apertures with sub-wavelength sizes

  15. Suitability of thin-layer chromatography-flame ionization detection with regard to quantitative characterization of different fossil fuel products. II. Calibration methods concerning quantitative hydrocarbon-group type analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vela, J.; Membrado, L.; Cebolla, V.L.; Ferrando, A.C. [CSIC, Zaragoza (Spain). Inst. de Carboquimica, Dept. de Procesos Quimicos

    1998-10-01

    Time-consuming external standard-based calibration methods are usually performed for hydrocarbon group type analysis (HGTA) of fossil fuels, regardless of the instrumental chromatographic technique. HGTA of a broad variety of coal and petroleum products was performed using a modern thin-layer chromatography-flame ionization detection (TLC-FID) system and a rapid method based on internal normalization. Repeatability, linear intervals, and sample load ranges for quantitative application of this method are given, namely a heavy oil and its derived hydrocracked products, raw and chemically-modified petroleum asphaltenes, a coal-tar pitch, several coal extracts, and coal hydroliquefaction products. Results from external standard calibration and a normalization method (both obtained by TLC-FID) are in agreement, and they are validated using TLC-ultraviolet scanning. The use of the latter demonstrates that TLC-FID can also be applied to products such as coal extracts and hydroliquefaction products, despite these products being more volatile than petroleum asphaltenes or heavy oils. 14 refs., 3 figs., 5 tabs.

  16. Recent Advances in Gas Barrier Thin Films via Layer-by-Layer Assembly of Polymers and Platelets.

    Science.gov (United States)

    Priolo, Morgan A; Holder, Kevin M; Guin, Tyler; Grunlan, Jaime C

    2015-05-01

    Layer-by-layer (LbL) assembly has emerged as the leading non-vacuum technology for the fabrication of transparent, super gas barrier films. The super gas barrier performance of LbL deposited films has been demonstrated in numerous studies, with a variety of polyelectrolytes, to rival that of metal and metal oxide-based barrier films. This Feature Article is a mini-review of LbL-based multilayer thin films with a 'nanobrick wall' microstructure comprising polymeric mortar and nano-platelet bricks that impart high gas barrier to otherwise permeable polymer substrates. These transparent, water-based thin films exhibit oxygen transmission rates below 5 × 10(-3) cm(3) m(-2) day(-1) atm(-1) and lower permeability than any other barrier material reported. In an effort to put this technology in the proper context, incumbent technologies such as metallized plastics, metal oxides, and flake-filled polymers are briefly reviewed. PMID:25800245

  17. Atomic layer deposition: a key technology for the controlled growth of oxide thin films for advanced applications

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD), also referred to as atomic layer epitaxy (ALE), was originally developed to process thin film electroluminescent structures for flat panel displays, which include as core components also insulating oxide layers such as alumina and aluminium titanium oxide. Another early application of oxide ALD was the processing of overlayers for catalysts. More recently, a major breakthrough for the ALD technology is the use of oxide thin films in microelectronics as gate and dynamic random access memory capacitor dielectrics. Besides giving a brief introduction to the ALD/ALE technology, the paper will address the present status of depositing binary and more complex (i.e. perovskite-type) metal oxides emphasizing precursor chemistry. (author)

  18. Delayed emission of 2p-1s and 3p-1s X-rays from 40 MeV neon ions ionized in a thin carbon foil

    International Nuclear Information System (INIS)

    A previous study of the He- and H-like lines of 40 MeV Ne projectiles excited by a thin carbon foil showed that the x-ray spectrum contains only He-like and H-like lines and that the intensities of these lines are sufficient to employ a high resolution curved crystal spectrometer to study the decay curves for individual transitions. Presented are Ne K x-ray spectra excited by passing a beam of 40 MeV ions through a 50 μg/cm2 carbon foil. They were taken at 0, 2.3, and 9.1 mm behind the foil and are normalized to the same total integrated charge in the carbon foil. The 1s2p(23P1)-1s2(11S0) transition is a spin-forbidden, metastable, intercombination line and has a lifetime of 1.85 x 10-10 sec8, whereas the He-like 1s2p(1P)-1s2(1S), H-like 2p(2P)-1s(2S), and H-like 3p(2P)-1s(2s) transitions are dipole-allowed with lifetimes of 1.13 x 10-13 sec8, 1.59 x 10-13 sec9, and 5.98 x 10-13 sec 10, respectively. It is apparent that even at 1 cm (i.e. 0.5 ns) behind the foil, considerable intensity is still detected for the short lifetime transitions indicating that electrons are cascading from very high n levels. Previous measurements and calculations have shown that the decay curves can be described by a power law of the form I = ct/sup -b/, where c and b are constants for a given line. It has been found that b depends on the initial n,l distribution. The measured decay curves for the delayed He-Like 1s2p(1P)-1s2(1S), H-like 2p-1s and H-like 3p-1s transitions are shown fitted to this power law

  19. A study on crystallization, optical and electrical properties of the advanced ZITO thin films using co-sputtering system

    International Nuclear Information System (INIS)

    Research highlights: Conductor and semiconductor ZITO transparent oxide thin films have been obtained by co-sputtering system. Therefore, we could fabricate a fully transparent ZITO optoelectronic device (thin film transistors or photodetector) in the future. The conducting ZITO was used as the electrode. The active layer of TFTs and photodetector employed the semiconducting ZITO. In addition, the investigation of luminescence characteristics on Zn-In-Sn-O (ZITO) film has never been reported. So, the multi-compound ZITO (ZnO combined ITO) films would be measured by photoluminescence (PL) to analyze the effects of ITO doping and oxygen gas content on emission characteristics of film. - Abstract: Multi-functions (conductor, semiconductor and insulator) ZnInSnO (ZITO) transparent oxide thin films have been obtained by a co-sputtering system using ITO target and ZnO target with oxygen gas contents (0-8%). The ZITO film containing a small ITO content had the lowest resistivity (good electron mobility) and higher optical transmittance. In addition, the influences of thermal treatments (post-annealing and substrate temperature) on electrical properties and optical transmittance of ZITO films were studied. Photoluminescence (PL) of the ZITO film confirmed the contribution of ITO content and oxygen gas content on the photo-emission. The ZITO film with zinc atomic concentration of 58 at.% was a good candidate for TCO material (3.08 x 10-4 Ω cm). Under the substrate temperature of 100 deg. C or post-annealing temperature of 200 oC, the properties of ZITO film could be improved.

  20. Thin film CIGS photovoltaic modules: monolithic integration and advanced packaging for high performance, high reliability and low cost

    Science.gov (United States)

    Eldada, Louay

    2011-01-01

    In recent years, thin-film photovoltaic companies started realizing their low manufacturing cost potential, and have been grabbing an increasingly larger market share. Copper Indium Gallium Selenide (CIGS) is the most promising thin-film PV material, having demonstrated the highest energy conversion efficiency in both cells and modules. However, most CIGS manufacturers still face the challenge of delivering a reliable and rapid manufacturing process that can scale effectively and deliver on the promise of this material system. HelioVolt has developed a reactive transfer process for CIGS absorber formation that has the benefits of good compositional control, and a fast high-quality CIGS reaction. The reactive transfer process is a two stage CIGS fabrication method. Precursor films are deposited onto substrates and reusable cover plates in the first stage, while in the second stage the CIGS layer is formed by rapid heating with Se confinement. HelioVolt also developed best-in-class packaging technologies that provide unparalleled environmental stability. High quality CIGS films with large grains were fabricated on the production line, and high-performance highreliability monolithic modules with a form factor of 120 cm × 60 cm are being produced at high yield and low cost. With conversion efficiency levels around 14% for cells and 12% for modules, HelioVolt is commercializing the process on its first production line with 20 MW capacity, and is planning its next GW-scale factory.

  1. Ionization gage

    International Nuclear Information System (INIS)

    An ionization manometer is proposed which contains a transducer consisting of an anode, a directly heated cathode and a collector, a power source, a cathode emission current stabilizer, an ionic current amplifier connected to a recorder, and a cathode emission current modulator. To increase the accuracy of measurements under conditions of vacuum evaporation of materials, the modulator has been designed to comprise a source of controlling electric unipolar pulses of a specified duration and frequency and a blocking device connected to the collector. The output of the source of controlling electric unipolar pulses is connected to the emission current stabilizer and to the second input of the blocking device whose output is connected to the ionic current amplifier. The amount of pressure exerted in the vacuum chamber is estimated from the magnitude of the variable constituent of the collector signal

  2. Prenatal exposition on ionizing radiations

    International Nuclear Information System (INIS)

    The Sessions on Prenatal Exposition on Ionizing Radiations was organized by the Argentine Radioprotection Society, in Buenos Aires, between 8 and 9, November 2001. In this event, were presented papers on: biological effects of ionizing radiation; the radiation protection and the pregnant woman; embryo fetal development and its relationship with the responsiveness to teratogens; radioinduced delayed mental; neonatal irradiation: neurotoxicity and modulation of pharmacological response; pre implanted mouse embryos as a model of uranium toxicity studies; hereditary effects of the radiation and new advances from the UNSCEAR 2001; doses estimation in embryo

  3. Electrical properties of radio-frequency sputtered HfO2 thin films for advanced CMOS technology

    International Nuclear Information System (INIS)

    The Hafnium oxide (HfO2) high-k thin films have been deposited by radio frequency (rf) sputtering technique on p-type Si (100) substrate. The thickness, composition and phases of films in relation to annealing temperatures have been investigated by using cross sectional FE-SEM (Field Emission Scanning Electron Microscope) and grazing incidence x-ray diffraction (GI-XRD), respectively. GI-XRD analysis revealed that at annealing temperatures of 350°C, films phases change to crystalline from amorphous. The capacitance-voltage (C-V) and current-voltage (I-V) characteristics of the annealed HfO2 film have been studied employing Al/HfO2/p-Si metal–oxide–semiconductor (MOS) structures. The electrical properties such as dielectric constant, interface trap density and leakage current density have been also extracted from C-V and I-V Measurements. The value of dielectric constant, interface trap density and leakage current density of annealed HfO2 film is obtained as 23,7.57×1011eV−1 cm−2 and 2.7×10−5 Acm−2, respectively. In this work we also reported the influence of post deposition annealing onto the trapping properties of hafnium oxide and optimized conditions under which no charge trapping is observed into the dielectric stack

  4. Advanced surface characterization of Ba(Fe0.92Co0.08)2As2 epitaxial thin films

    International Nuclear Information System (INIS)

    Highlights: • Epitaxial growth of Ba(Fe0.92Co0.08)2As2 films on (0 0 1) CaF2 substrate by PLD has been achieved. • Morphological studies by RHEED, SEM, and AFM identified that Ba(Fe0.92Co0.08)2As2 grows in a terraced island mode. • Smooth surface (RMS value of 1.15 nm) was obtained. • Homogeneous superconducting properties over the film were confirmed by various electro-magnetic measurements. - Abstract: We report on the systematic characterization of Ba(Fe0.92Co0.08)2As2 epitaxial thin films on CaF2 substrate in view of their possible use for superconducting electronic applications. By using different and complementary techniques we studied the morphological characteristics of the surface, the structural properties, the magnetic response, and the superconducting properties in terms of critical temperature, critical current, and energy gaps. Particular attention was paid to the homogeneity of the films and to the comparison of their superconducting properties with those of single crystals of the same compound

  5. Sol-gel optical thin films for an advanced megajoule-class Nd:glass laser ICF-driver

    International Nuclear Information System (INIS)

    It is well established by manufacturers and users that optical coatings are generally prepared by the well known Physical Vapor Deposition (PVD) technology. In the authors' opinion sol-gel technology is an effective and competitive alternative. The aim of this paper is to emphasize on the sol-gel thin film work carried out at Centre d'Etudes de Limeil-Valenton (CEL-V) and concerning the technology for high power lasers. The authors will briefly discuss the chemistry of the sol-gel process, the production of optical coatings and the related deposition techniques. Finally, the paper describes the preparation and performance of sol-gel optical coatings they have developed to fulfill the requirements of a future 2 MJ/500 TW (351 nm) pulsed Nd:glass laser so-called LMJ (Laser MegaJoules). This powerful laser is to be used for their national Inertial Confinement Fusion (ICF) program, to demonstrate at the laboratory scale, ignition of deuterium-tritium fusion fuel. Moreover, the aim of this article is, hopefully, to provide a convincing argument that coatings and particularly optical coatings, are some of the useful products available from sol-gel technology, and that exciting developments in other areas are almost certain to emerge within the coming decade

  6. Electrical properties of radio-frequency sputtered HfO2 thin films for advanced CMOS technology

    Science.gov (United States)

    Sarkar, Pranab Kumar; Roy, Asim

    2015-08-01

    The Hafnium oxide (HfO2) high-k thin films have been deposited by radio frequency (rf) sputtering technique on p-type Si (100) substrate. The thickness, composition and phases of films in relation to annealing temperatures have been investigated by using cross sectional FE-SEM (Field Emission Scanning Electron Microscope) and grazing incidence x-ray diffraction (GI-XRD), respectively. GI-XRD analysis revealed that at annealing temperatures of 350°C, films phases change to crystalline from amorphous. The capacitance-voltage (C-V) and current-voltage (I-V) characteristics of the annealed HfO2 film have been studied employing Al/HfO2/p-Si metal-oxide-semiconductor (MOS) structures. The electrical properties such as dielectric constant, interface trap density and leakage current density have been also extracted from C-V and I-V Measurements. The value of dielectric constant, interface trap density and leakage current density of annealed HfO2 film is obtained as 23,7.57×1011eV-1 cm-2 and 2.7×10-5 Acm-2, respectively. In this work we also reported the influence of post deposition annealing onto the trapping properties of hafnium oxide and optimized conditions under which no charge trapping is observed into the dielectric stack.

  7. Wafer-Scale Integration of Inverted Nanopyramid Arrays for Advanced Light Trapping in Crystalline Silicon Thin Film Solar Cells.

    Science.gov (United States)

    Zhou, Suqiong; Yang, Zhenhai; Gao, Pingqi; Li, Xiaofeng; Yang, Xi; Wang, Dan; He, Jian; Ying, Zhiqin; Ye, Jichun

    2016-12-01

    Crystalline silicon thin film (c-Si TF) solar cells with an active layer thickness of a few micrometers may provide a viable pathway for further sustainable development of photovoltaic technology, because of its potentials in cost reduction and high efficiency. However, the performance of such cells is largely constrained by the deteriorated light absorption of the ultrathin photoactive material. Here, we report an efficient light-trapping strategy in c-Si TFs (~20 μm in thickness) that utilizes two-dimensional (2D) arrays of inverted nanopyramid (INP) as surface texturing. Three types of INP arrays with typical periodicities of 300, 670, and 1400 nm, either on front, rear, or both surfaces of the c-Si TFs, are fabricated by scalable colloidal lithography and anisotropic wet etch technique. With the extra aid of antireflection coating, the sufficient optical absorption of 20-μm-thick c-Si with a double-sided 1400-nm INP arrays yields a photocurrent density of 39.86 mA/cm(2), which is about 76 % higher than the flat counterpart (22.63 mA/cm(2)) and is only 3 % lower than the value of Lambertian limit (41.10 mA/cm(2)). The novel surface texturing scheme with 2D INP arrays has the advantages of excellent antireflection and light-trapping capabilities, an inherent low parasitic surface area, a negligible surface damage, and a good compatibility for subsequent process steps, making it a good alternative for high-performance c-Si TF solar cells. PMID:27071681

  8. Wafer-Scale Integration of Inverted Nanopyramid Arrays for Advanced Light Trapping in Crystalline Silicon Thin Film Solar Cells

    Science.gov (United States)

    Zhou, Suqiong; Yang, Zhenhai; Gao, Pingqi; Li, Xiaofeng; Yang, Xi; Wang, Dan; He, Jian; Ying, Zhiqin; Ye, Jichun

    2016-04-01

    Crystalline silicon thin film (c-Si TF) solar cells with an active layer thickness of a few micrometers may provide a viable pathway for further sustainable development of photovoltaic technology, because of its potentials in cost reduction and high efficiency. However, the performance of such cells is largely constrained by the deteriorated light absorption of the ultrathin photoactive material. Here, we report an efficient light-trapping strategy in c-Si TFs (~20 μm in thickness) that utilizes two-dimensional (2D) arrays of inverted nanopyramid (INP) as surface texturing. Three types of INP arrays with typical periodicities of 300, 670, and 1400 nm, either on front, rear, or both surfaces of the c-Si TFs, are fabricated by scalable colloidal lithography and anisotropic wet etch technique. With the extra aid of antireflection coating, the sufficient optical absorption of 20-μm-thick c-Si with a double-sided 1400-nm INP arrays yields a photocurrent density of 39.86 mA/cm2, which is about 76 % higher than the flat counterpart (22.63 mA/cm2) and is only 3 % lower than the value of Lambertian limit (41.10 mA/cm2). The novel surface texturing scheme with 2D INP arrays has the advantages of excellent antireflection and light-trapping capabilities, an inherent low parasitic surface area, a negligible surface damage, and a good compatibility for subsequent process steps, making it a good alternative for high-performance c-Si TF solar cells.

  9. Advancements in artificial heart valve disks using nano-sized thin films deposited by CVD and sol-gel techniques

    International Nuclear Information System (INIS)

    Pyrolytic carbon (PyC) is widely used in manufacturing commercial artificial heart valve disks (HVD). Although, PyC is commonly used in HVD, it is not the best material for this application since its blood compatibility is not ideal for prolonged clinical use. As a result thrombosis often occurs and the patients are required to take anti- coagulation drugs on a regular basis in order to minimise the formation of thrombosis. However, the anti-coagulation therapy gives rise to some detrimental side effects in patients. Therefore, it is extremely urgent that newer and more technically advanced materials with better surface and bulk properties are developed. In this paper, we report the mechanical properties of PyC-HVD, namely, strength, wear resistance and coefficient of friction. The strength of the material was assessed using Brinell indentation tests. Furthermore, wear resistance and the coefficient of friction values were obtained from the pin-on-disk testing. The micro-structural properties of PyC were characterized using XRD, Raman spectroscopy and SEM analysis. Also, in this paper we report the preparation of free standing nanocrystalline diamond films (FSND) using the time-modulated chemical vapor deposition (TMCVD) process. Furthermore, the sol-gel technique was used to uniformly coat PyC-HVD with dense, nanocrystalline-titanium oxide (nc-TiO/sub 2/) coatings. The as-grown nc-TiO/sub 2/ coatings were characterized for microstructure using SEM and XRD analysis. (author)

  10. Ultrafast ionization and fragmentation of molecular silane

    International Nuclear Information System (INIS)

    The ionization and fragmentation of molecular silane is examined here with laser intensities ranging between 7x1012 and 1x1015 W/cm2 at 624 nm. The ionization potential of silane determined using both multiphoton ionization (MPI) and tunneling ionization (TI) models agrees with the vertical ionization potential of the molecule. In addition, the application of the tunneling ionization model is extended here to the fragments of silane to determine their appearance potentials. MPI values for SiH3+, SiH2+, SiH+, Si+, as well as H2+ and H+ are consistent with vertical potentials, whereas the TI measurements are found to be in accord with adiabatic potentials. The tunneling appearance potentials observed for the fragments H2+ and H+ are lower than reported for other techniques. In fact, the appearance potential measurements for these species resulting from silane are lower than their ionization potentials. The fragmentation rate of silane is determined to be nearly 20 times larger than the ionization rate. The main precursor for producing amorphous silicon (a-Si:H) thin films, SiH3+ is the dominant fragmentation product making up roughly a third of the total ion yield, a substantial increase from other techniques.

  11. Designing nanoscale constructs from atomic thin sheets of graphene, boron nitride and gold nanoparticles for advanced material applications

    Science.gov (United States)

    Jasuja, Kabeer

    2011-12-01

    Nanoscale materials invite immense interest from diverse scientific disciplines as these provide access to precisely understand the physical world at their most fundamental atomic level. In concert with this aim of enhancing our understanding of the fundamental behavior at nanoscale, this dissertation presents research on three nanomaterials: Gold nanoparticles (GNPs), Graphene and ultra-thin Boron Nitride sheets (UTBNSs). The three-fold goals which drive this research are: incorporating mobility in nanoparticle based single-electron junction constructs, developing effective strategies to functionalize graphene with nano-forms of metal, and exfoliating ultrathin sheets of Boron Nitride. Gold nanoparticle based electronic constructs can achieve a new degree of operational freedom if nanoscale mobility is incorporated in their design. We achieved such a nano-electromechanical construct by incorporating elastic polymer molecules between GNPs to form 2-dimensional (2-D) molecular junctions which show a nanoscale reversible motion on applying macro scale forces. This GNP-polymer assembly works like a molecular spring opening avenues to maneuver nano components and store energy at nano-scale. Graphene is the first isolated nanomaterial that displays single-atom thickness. It exhibits quantum confinement that enables it to possess a unique combination of fascinating electronic, optical, and mechanical properties. Modifying the surface of graphene is extremely significant to enable its incorporation into applications of interest. We demonstrated the ability of chemically modified graphene sheets to act as GNP stabilizing templates in solution, and utilized this to process GNP composites of graphene. We discovered that GNPs synthesized by chemical or microwave reduction stabilize on graphene-oxide sheets to form snow-flake morphologies and bare-surfaces respectively. These hybrid nano constructs were extensively studied to understand the effect and nature of GNPs

  12. Transient terahertz photoconductivity measurements of minority-carrier lifetime in tin sulfide thin films: Advanced metrology for an early stage photovoltaic material

    Science.gov (United States)

    Jaramillo, R.; Sher, Meng-Ju; Ofori-Okai, Benjamin K.; Steinmann, V.; Yang, Chuanxi; Hartman, Katy; Nelson, Keith A.; Lindenberg, Aaron M.; Gordon, Roy G.; Buonassisi, T.

    2016-01-01

    Materials research with a focus on enhancing the minority-carrier lifetime of the light-absorbing semiconductor is key to advancing solar energy technology for both early stage and mature material platforms alike. Tin sulfide (SnS) is an absorber material with several clear advantages for manufacturing and deployment, but the record power conversion efficiency remains below 5%. We report measurements of bulk and interface minority-carrier recombination rates in SnS thin films using optical-pump, terahertz-probe transient photoconductivity (TPC) measurements. Post-growth thermal annealing in H2S gas increases the minority-carrier lifetime, and oxidation of the surface reduces the surface recombination velocity. However, the minority-carrier lifetime remains below 100 ps for all tested combinations of growth technique and post-growth processing. Significant improvement in SnS solar cell performance will hinge on finding and mitigating as-yet-unknown recombination-active defects. We describe in detail our methodology for TPC experiments, and we share our data analysis routines in the form freely available software.

  13. Ionization Energies of Lanthanides

    Science.gov (United States)

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  14. Foodstuffs preservation by ionization

    International Nuclear Information System (INIS)

    This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)

  15. Development of advanced internal gain radiation detector structures based on neutron transmutation doped silicon, High T/sub c/ superconductive compounds and their potential application to detection of ionizing radiation: Annual report, December 1, 1986-November 30, 1987

    International Nuclear Information System (INIS)

    This report covers the period of work from December 1, 1986 through November 30, 1987. The work on mercuric iodide has now entered a new and more developmental phase with support now being obtained from other agencies (NIH, NASA, JPL, the CalTech President's Fund etc.) for specific, directed applications. These include development of arrays of HgI2 x-ray spectrometers for synchrotron radiation application supported by NIH and for long term space mission use supported by NASA. It has been undertaken during the past year (with some work done in the previous year) to re-examine the technology of high field ''avalanche'' radiation detector structures which use the ''controlled surface'' principle as developed previously under DOE sponsorship. This was undertaken because of the advent of a fundamental advance in silicon single crystal technology -''neutron transmutation doped'' or ''NTD'' single crystal. This new material conceptually solves a basic problem that previously halted the development of these potentially useful radiation detection structures. That problem was the non-uniform, (or ''striated'') distribution of donor impurities which adversely affected electric field distribution and thus attainable avalanche gain in these structures. A new effort started late in the year springs from the development of high critical temperature superconducting ceramic compounds. In essence, the phenomenon of superconductivity can now be achieved at temperatures reached by liquid nitrogen rather than expensive and more complicated cryogenic helium. This, in essence, then brings superconductivity into the same temperature range where lithium drifted silicon and intrinsic germanium already operate. The usefulness of superconductivity in detection and spectroscopy of ionizing radiations based on the narrow superconductive band gap is very appealing and we have begun theoretical (presented herein) and experimental studies investigating these new materials

  16. New constraints on the escape of ionizing photons from starburst galaxies using ionization-parameter mapping

    International Nuclear Information System (INIS)

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough (≳3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough (≲5 Myr) that the ionizing stars are still present.

  17. Thin silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  18. Ferroelectric thin films

    International Nuclear Information System (INIS)

    The area of ferroelectric thin films has expanded rapidly recently with the advent of high quality multi-oxide deposition technology. Advances in thin film quality has resulted in the realization of new technologies not achievable through classical bulk ceramic processing techniques. An example of this progress is the co-processing of ferroelectric thin films with standard semiconductor silicon and GaAs integrated circuits for radiation hard, non-volatile memory products. While the development of this class of products is still embryonic, the forecasted market potential is rapidly out distancing the combined developmental effort. Historically the greatest use of bulk ferroelectric material has been in sensor technology, utilizing the pyroelectric and piezoelectric properties of the material. By comparison, a relatively small development effort has been reported for ferroelectric thin film senor technology, a field sure to provide exciting advances in the future. The papers in this proceedings volume were presented at the first symposium dedicated to the field of ferroelectric thin films held by the Materials Research Society at the Spring 1990 Meeting in San Francisco, CA, April 16-20, 1990. The symposium was designed to provide a comprehensive tutorial covering the newest advances of ferroelectric thin films, including material systems, new deposition techniques and physical, electrical and electro-optic characterization

  19. Resonance ionization spectroscopy 1986

    International Nuclear Information System (INIS)

    The paper presents the proceedings of the Third International Symposium on Resonance Ionization Spectroscopy and its Applications, held at the University College of Swansea, Wales, 1986. The Symposium is divided into eight main sections entitled: photophysics and spectroscopy, noble gas atom counting, resonance ionization mass spectrometry, materials and surface analysis, small molecules, medical and environmental applications, resonance ionization and materials separation, and elementary particles and nuclear physics. Thirty papers were chosen for INIS and indexed separately. (U.K.)

  20. Abnormal ionization in sonoluminescence

    Institute of Scientific and Technical Information of China (English)

    张文娟; 安宇

    2015-01-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%–70%as the bubble flashes, which is difficult to explain by using previous models.

  1. Ionizing Radiation and Life

    OpenAIRE

    Dartnell, L. R.

    2011-01-01

    Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and ...

  2. Analytical instruments, ionization sources, and ionization methods

    Science.gov (United States)

    Atkinson, David A.; Mottishaw, Paul

    2006-04-11

    Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.

  3. Dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

  4. High spatial resolution dosimetric response maps for radiotherapy ionization chambers measured using kilovoltage synchrotron radiation.

    Science.gov (United States)

    Butler, D J; Stevenson, A W; Wright, T E; Harty, P D; Lehmann, J; Livingstone, J; Crosbie, J C

    2015-11-21

    Small circular beams of synchrotron radiation (0.1 mm and 0.4 mm in diameter) were used to irradiate ionization chambers of the types commonly used in radiotherapy. By scanning the chamber through the beam and measuring the ionization current, a spatial map of the dosimetric response of the chamber was recorded. The technique is able to distinguish contributions to the large-field ionization current from the chamber walls, central electrode and chamber stem. Scans were recorded for the NE 2571 Farmer chamber, the PTW 30013, IBA FC65-G Farmer-type chambers, the NE 2611A and IBA CC13 thimble chambers, the PTW 31006 and 31014 pinpoint chambers, the PTW Roos and Advanced Markus plane-parallel chambers, and the PTW 23342 thin-window soft x-ray chamber. In all cases, large contributions to the response arise from areas where the incident beam grazes the cavity surfaces. Quantitative as well as qualitative information about the relative chamber response was extracted from the maps, including the relative contribution of the central electrode. Line scans using monochromatic beams show the effect of the photon energy on the chamber response. For Farmer-type chambers, a simple Monte Carlo model was in good agreement with the measured response. PMID:26510214

  5. High spatial resolution dosimetric response maps for radiotherapy ionization chambers measured using kilovoltage synchrotron radiation

    International Nuclear Information System (INIS)

    Small circular beams of synchrotron radiation (0.1 mm and 0.4 mm in diameter) were used to irradiate ionization chambers of the types commonly used in radiotherapy. By scanning the chamber through the beam and measuring the ionization current, a spatial map of the dosimetric response of the chamber was recorded. The technique is able to distinguish contributions to the large-field ionization current from the chamber walls, central electrode and chamber stem. Scans were recorded for the NE 2571 Farmer chamber, the PTW 30013, IBA FC65-G Farmer-type chambers, the NE 2611A and IBA CC13 thimble chambers, the PTW 31006 and 31014 pinpoint chambers, the PTW Roos and Advanced Markus plane-parallel chambers, and the PTW 23342 thin-window soft x-ray chamber. In all cases, large contributions to the response arise from areas where the incident beam grazes the cavity surfaces. Quantitative as well as qualitative information about the relative chamber response was extracted from the maps, including the relative contribution of the central electrode. Line scans using monochromatic beams show the effect of the photon energy on the chamber response. For Farmer-type chambers, a simple Monte Carlo model was in good agreement with the measured response. (paper)

  6. Multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    The paper is devoted to the analysis of high intensity effects which result from multiphoton ionization of atoms in a high laser intensity, ranging from 1010 to 1015 W cm-2. Resonant multiphoton ionization of atoms, the production of multiply charged ions, and electron energy spectra, are all discussed. (U.K.)

  7. Application of ionizing radiation

    International Nuclear Information System (INIS)

    Fundamental studies by the Nuclear Research Institute concerning the use of ionizing radiations are reported. The ROZA irradiation plant is used for sterilization in medicine and for historic objects preservation. Ionizing radiation is used in the radiation treatment of cables and drinking water. Radiopharmaceuticals are developed. The Institute is an all-state centre for research and development of semiconductor detectors. (M.S.)

  8. Multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    This article provides an overview of the current understanding of multiphoton ionization of atoms. It begins with an introductory section to explain the background of the subject. Then the article develops the three topics which have been central themes of discussion in multiphoton ionization of atoms these past few years: multiply charged ion production, very high order harmonic generation, and above-threshold ionization, a name given to the absorption of a very large number of photons by an already ionized electron. A large part of the review is devoted to some theoretical aspects of multiphoton ionization of atoms and especially non-perturbative theories. Finally the article considers the very near future prospects of laser-electron interactions and more generally laser-matter interactions at 1018 -1019 W cm-2, an intensity range now within reach due to new short pulse laser technology. (author)

  9. Chemical synthesis of α-La{sub 2}S{sub 3} thin film as an advanced electrode material for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Patil, S.J.; Kumbhar, V.S.; Patil, B.H.; Bulakhe, R.N.; Lokhande, C.D., E-mail: l_chandrakant@yahoo.com

    2014-10-25

    Highlights: • The simple, chemical method used for synthesis of lanthanum sulphide thin films. • The lanthanum sulphide thin film surface exhibited porous microstructure. • The lanthanum sulphide thin film electrode is used for supercapacitor application. - Abstract: α-La{sub 2}S{sub 3} thin films have been synthesized for the first time by successive ionic layer adsorption and reaction (SILAR) method and used for supercapacitor application. These films are characterized for crystal structure, surface morphology and wettability studies using X-ray diffraction (XRD), Fourier Transform-Raman (FT-Raman) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements. The electrochemical supercapacitive performance of α-La{sub 2}S{sub 3} electrode is evaluated by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. From the electrochemical study, it is seen that α-La{sub 2}S{sub 3} electrode delivers high specific capacitance of 256 F g{sup −1} at scan rate of 5 mV s{sup −1} with cycling stability of 85% over 1000 cycles. Such La{sub 2}S{sub 3} electrode has great application in supercapacitor device for energy storage.

  10. New Constraints on the Escape of Ionizing Photons From Starburst Galaxies Using Ionization-Parameter Mapping

    CERN Document Server

    Zastrow, Jordan; Veilleux, Sylvain; McDonald, Michael

    2013-01-01

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [SIII]/[SII] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrow-band images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40+/-5 degrees (0.4 ster), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble act...

  11. Biological Effects of Ionizing Radiation

    Science.gov (United States)

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  12. Scintillations in ionization chambers

    International Nuclear Information System (INIS)

    High purity Ar and mixtures of Ar with 1% CH4, 3% CH4, CO2 and N2, respectively, have been applied for fission fragment detection in a gridded ionization chamber. Gas scintillation has been observed simultaneously with a photomultiplier VALVO-XP 2041. Whereas all mixtures work equally well as an ionization gas, only Ar + 3% N2 shows a primary scintillation yield sufficient for fas timing. (orig.)

  13. MULTIPHOTON IONIZATION OF ATOMS

    OpenAIRE

    Mainfray, G.

    1985-01-01

    Multiphoton ionization of one-electron atoms, such as atomic hydrogen and alkaline atoms, is well understood and correctly described by rigorous theoretical models. The present paper will be devoted to collisionless multiphoton ionization of many-electron atoms as rare gases. It induces removal of several electrons and the production of multiply charged ions. Up to Xe5+ ions are produced in Xe atoms. Doubly charged ions can be produced, either by simultaneous excitation of two electrons, or b...

  14. "Magic" Ionization Mass Spectrometry

    Science.gov (United States)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  15. Alkali metal ionization detector

    Science.gov (United States)

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  16. "Magic" Ionization Mass Spectrometry.

    Science.gov (United States)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers. PMID:26486514

  17. The GODDESS ionization chamber: developing robust windows

    Science.gov (United States)

    Blanchard, Rose; Baugher, Travis; Cizewski, Jolie; Pain, Steven; Ratkiewicz, Andrew; Goddess Collaboration

    2015-10-01

    Reaction studies of nuclei far from stability require high-efficiency arrays of detectors and the ability to identify beam-like particles, especially when the beam is a cocktail beam. The Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS) is made up of the Oak Ridge-Rutgers University Barrel Array (ORRUBA) of silicon detectors for charged particles inside of the gamma-ray detector array Gammasphere. A high-rate ionization chamber is being developed to identify beam-like particles. Consisting of twenty-one alternating anode and cathode grids, the ionization chamber sits downstream of the target chamber and is used to measure the energy loss of recoiling ions. A critical component of the system is a thin and robust mylar window which serves to separate the gas-filled ionization chamber from the vacuum of the target chamber with minimal energy loss. After construction, windows were tested to assure that they would not break below the required pressure, causing harm to the wire grids. This presentation will summarize the status of the ionization chamber and the results of the first tests with beams. This work is supported in part by the U.S. Department of Energy and National Science Foundation.

  18. Effect of post-deposition annealing temperature on RF-sputtered HfO2 thin film for advanced CMOS technology

    Science.gov (United States)

    Khairnar, A. G.; Mahajan, A. M.

    2013-01-01

    Structural and electrical properties of HfO2 gate-dielectric metal-oxide-semiconductor (MOS) capacitors deposited by sputtering are investigated. The HfO2 high-k thin films have been deposited on p-type silicon wafer using RF-Magnetron sputtering technique. The Ellipsometric, FTIR and AFM characterizations have been done. The thickness of the as deposited film is measured to be 35.38 nm. Post deposition annealing in N2 ambient is carried out at 350, 550, 750 °C. The chemical bonding and surface morphology of the film is verified using FTIR and AFM respectively. The structural characterization confirmed that the thin film was free of physical defects and root mean square surface roughness decreased as the annealing temperature increased. The smooth surface HfO2 thin films were used for Al/HfO2/p-Si MOS structures fabrication. The fabricated Al/HfO2/p-Si structure had been used for extracting electrical properties such as dielectric constant, EOT, interface trap density and leakage current density through capacitance voltage and current voltage measurements. The interface state density extracted from the G-V measurement using Hill Coleman method. Sample annealed at 750 °C showed the lowest interface trap density (3.48 × 1011 eV-1 cm-2), effective oxide charge (1.33 × 1012 cm-2) and low leakage current density (3.39 × 10-9 A cm-2) at 1.5 V.

  19. Fundamental Materials Research and Advanced Process Development for Thin-Film CIS-Based Photovoltaics: Final Technical Report, 2 October 2001 - 30 September 2005

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T. J.; Li, S. S.; Crisalle, O. D.; Craciun, V.

    2006-09-01

    The objectives for this thin-film copper-indium-diselenide (CIS) solar cell project cover the following areas: Develop and characterize buffer layers for CIS-based solar cell; grow and characterize chemical-bath deposition of Znx Cd1-xS buffer layers grown on CIGS absorbers; study effects of buffer-layer processing on CIGS thin films characterized by the dual-beam optical modulation technique; grow epitaxial CuInSe2 at high temperature; study the defect structure of CGS by photoluminescence spectroscopy; investigate deep-level defects in Cu(In,Ga)Se2 solar cells by deep-level transient spectroscopy; conduct thermodynamic modeling of the isothermal 500 C section of the Cu-In-Se system using a defect model; form alpha-CuInSe2 by rapid thermal processing of a stacked binary compound bilayer; investigate pulsed non-melt laser annealing on the film properties and performance of Cu(In,Ga)Se2 solar cells; and conduct device modeling and simulation of CIGS solar cells.

  20. Fuel cell with ionization membrane

    Science.gov (United States)

    Hartley, Frank T. (Inventor)

    2007-01-01

    A fuel cell is disclosed comprising an ionization membrane having at least one area through which gas is passed, and which ionizes the gas passing therethrough, and a cathode for receiving the ions generated by the ionization membrane. The ionization membrane may include one or more openings in the membrane with electrodes that are located closer than a mean free path of molecules within the gas to be ionized. Methods of manufacture are also provided.

  1. 2.2.1 Ionizing Radiation

    Science.gov (United States)

    Kasch, K.-U.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.2.1 Ionizing Radiation' of the Section '2.2 Kinds of Radiation' of the Chapter '2 Radiation and Biological Effects' with the contents:

  2. Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

    International Nuclear Information System (INIS)

    Currently sputtered Al-doped ZnO films are transferred to industry for the application in thin film silicon solar modules. These films are known to easily form light trapping structures upon etching which are necessary for absorbers with low absorbance such as μc-Si. Up to now the best structures for high efficiency thin film silicon solar cells were obtained by low rate radio frequency (r.f.) sputtering of ceramic targets. However, for industrial application a high rate process is essential. Therefore a seed layer approach was developed to increase the deposition rate while keeping the desired etch morphology and electrical properties. Aluminum doped ZnO films were deposited dynamically by direct current (d.c.) magnetron sputtering from a ceramic ZnO:Al2O3 target (1 wt.%) onto an additional seed layer prepared by r.f. sputtering. ZnO:Al films were investigated with respect to their optical and electrical properties as well as the morphology created after etching for a-Si/μc-Si solar cells. Additionally atomic force microscopy, scanning electron microscopy, X-ray diffraction and Hall measurements were performed, comparing purely r.f. or d.c. sputtered films with d.c. sputtered films on seed layers. With the seed layer approach it was possible to deposit ZnO:Al films with a visual transmittance of 83.5%, resistivity of 295 μΩ cm, electron mobility of 48.9 cm2/Vs and electron density of 4.3 · 1020 cm−3 from a ceramic target at 330 °C. Etch morphologies with 1 μm lateral structure size were achieved. - Highlights: ► Seed layer approach for dynamic sputter deposition of enhanced quality ZnO:Al. ► A thin radio frequency sputtered ZnO:Al layer assists film nucleation on glass. ► Electron mobility was increased up to 49 cm2/Vs due to quasi-epitaxial film growth. ► Etch morphology exhibits 1 μm wide craters for light trapping in solar cells. ► The concept was transferred to a seed layer sputtered with direct current

  3. Stochastic processes in muon ionization cooling

    Science.gov (United States)

    Errede, D.; Makino, K.; Berz, M.; Johnstone, C. J.; Van Ginneken, A.

    2004-02-01

    A muon ionization cooling channel consists of three major components: the magnet optics, an acceleration cavity, and an energy absorber. The absorber of liquid hydrogen contained by thin aluminum windows is the only component which introduces stochastic processes into the otherwise deterministic acceleration system. The scattering dynamics of the transverse coordinates is described by Gaussian distributions. The asymmetric energy loss function is represented by the Vavilov distribution characterized by the minimum number of collisions necessary for a particle undergoing loss of the energy distribution average resulting from the Bethe-Bloch formula. Examples of the interplay between stochastic processes and deterministic beam dynamics are given.

  4. Transient terahertz photoconductivity measurements of minority-carrier lifetime in tin sulfide thin films: Advanced metrology for an early stage photovoltaic material

    OpenAIRE

    Jaramillo, R.; Sher, Meng-Ju; Ofori-Okai, Benjamin; Steinmann, V; Yang, Chuanxi; Hartman, Katy; Nelson, Keith; Lindenberg, Aaron; Gordon, Roy Gerald; Buonsassisi, T

    2016-01-01

    Materials research with a focus on enhancing the minority-carrier lifetime of the light-absorbing semiconductor is key to advancing solar energy technology for both early stage and mature material platforms alike. Tin sulfide (SnS) is an absorber material with several clear advantages for manufacturing and deployment, but the record power conversion efficiency remains below 5%. We report measurements of bulk and interface minority-carrier recombination rates in SnSthin films using optical-pum...

  5. The critical ionization velocity

    International Nuclear Information System (INIS)

    The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (author)

  6. The critical ionization velocity

    International Nuclear Information System (INIS)

    The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (Auth.)

  7. The ionizing treatment of food

    International Nuclear Information System (INIS)

    This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

  8. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  9. Ionizing radiation detecting unit

    International Nuclear Information System (INIS)

    A design of a unit for ionizing radiation detection under high mechanical loads is described. The unit consists of a detector (scintillation or ionization), switching unit, an electronic unit, a compensation unit and absorption unit, and a jacket. To increase reliability of the unit under operation conditions at any space position in the wide range of mechanical loads and to simplify the construction, the absorption assembly has been made in the form of an elastic reference barrel-shaped element with slots along the element surface and connected to the switching unit and electronic unit by the compensation unit, which ridigity is higher than the element ridigity

  10. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  11. Alkali ionization detector

    Science.gov (United States)

    Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

    1982-01-01

    A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

  12. Ionization beam scanner

    CERN Multimedia

    1973-01-01

    Inner structure of an ionization beam scanner, a rather intricate piece of apparatus which permits one to measure the density distribution of the proton beam passing through it. On the outside of the tank wall there is the coil for the longitudinal magnetic field, on the inside, one can see the arrangement of electrodes creating a highly homogeneous transverse electric field.

  13. Ionization chamber smoke detectors

    International Nuclear Information System (INIS)

    One kind of smoke detector, the ionization-type, is regulated by the Atomic Energy Control Board (AECB) because it uses a radioactive substance in its mechanism. Radioactivity and radiation are natural phenomena, but they are not very familiar to the average householder. This has led to a number of questions being asked of the AECB. These questions and AECB responses are outlined

  14. Critical ionization velocity interaction

    International Nuclear Information System (INIS)

    Different problems of current interest regarding the critical ionization velocity (CIV) phenomenon are discussed. The article is divided into five sections corresponding to different aspects of the interaction: velocity, magnetic field strength, geometry, neutral gas density, and time duration. In each section, experiments and theories - microscopic and macroscopic - are discussed

  15. Applications of ionizing radiations

    International Nuclear Information System (INIS)

    The R and D activities of the application of Ionizing Radiations Program is comprised to four subprograms: Food and Agricultural Productions Irradiation; Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; and Radioactive Facilities and Equipment for Nuclear Techniques Applications

  16. 液基膜式薄层细胞学技术进展%Advance of liquid polyimides type thin layer cytology technology

    Institute of Scientific and Technical Information of China (English)

    马福军; 王占红; 刘海波; 刘铁军

    2011-01-01

    @@ 液基膜式薄层细胞学技术是正在探索的一项新技术,它是将细胞收集在保存液中,利用计算机控制的自动化技术制备薄层细胞涂片.其中较有代表性的是在制片中采用了微孔薄膜过滤方法的TCT技术.1996-05美国食品及药物管理局(FDA)批准把此法用于临床.1999 年被引入国内,也称TCT (ThinPrep Cytology Test) 检测.现在TCT技术已被广泛应用于宫颈癌的筛查工作中,因其具有背景干净,没有血细胞及炎细胞干扰,细胞保存完好,结构清晰等特点,亦被用于体腔积液、尿液、纤维支气管刷片、细针穿刺细胞学等其他脱落细胞学检查中[1-4].为了提高对TCT 的认识,笔者特作综述如下.

  17. All short pulse multiphoton ionization is resonant ionization

    International Nuclear Information System (INIS)

    Energy resolved photoelectron spectra of multiphoton ionization taken with a 300 fs laser pulse at 616 nm shows that the ionization probability is highly structured as a function of laser intensity. The spectrum is consistent with all of the ionization occurring at intensity resonances

  18. Thin Nanoporous Metal-Insulator-Metal Membranes.

    Science.gov (United States)

    Aramesh, Morteza; Djalalian-Assl, Amir; Aghili Yajadda, Mir Massoud; Prawer, Steven; Ostrikov, Kostya Ken

    2016-02-24

    Insulating nanoporous materials are promising platforms for soft-ionizing membranes; however, improvement in fabrication processes and the quality and high breakdown resistance of the thin insulator layers are needed for high integration and performance. Here, scalable fabrication of highly porous, thin, silicon dioxide membranes with controlled thickness is demonstrated using plasma-enhanced chemical-vapor-deposition. The fabricated membranes exhibit good insulating properties with a breakdown voltage of 1 × 10(7) V/cm. Our calculations suggest that the average electric field inside a nanopore of the membranes can be as high as 1 × 10(6) V/cm; sufficient for ionization of wide range of molecules. These metal-insulator-metal nanoporous arrays are promising for applications such soft ionizing membranes for mass spectroscopy. PMID:26846250

  19. Electrochemical reactions and ionization processes

    OpenAIRE

    Girault, Hubert; Liu, Baohong; Qiao, Liang; Bi, Hongyan; Prudent, Michel; Lion, Niels; Abonnenc, Mélanie

    2010-01-01

    Electrochemical or photo-electrochemical reactions in both electrospray ionization and laser desorption ionization are discussed stressing the role of the electrode reaction in influencing the ionization process. In particular, upon application of a high voltage during electrospray ionization, the emitter includes a working electrode, where redox reactions are observed, such as electro-generation of benzoquinone and metal ions. In contrast, the target plate in laser-induced desorption ionizat...

  20. Multiphoton ionization of polarized atoms

    International Nuclear Information System (INIS)

    A theory is derived for the multiphoton ionization of polarized atoms. The angular distributions of the differential and total ionization probabilities are studied for various polarizations of the electromagnetic radiation. The circular dichroism is also studied. The multiphoton ionization of oriented s-state atoms near a resonance is studied separately. Some relevant experiments which might be carried out are discussed

  1. Multiphoton ionization of polarized atoms

    International Nuclear Information System (INIS)

    A theory of multiphoton ionization of polarized atoms is developed. The angular dependences of the different and total ionization probabilities for various polarizations of the radiation and the circular dichroism effect are investigated. Multiphoton ionization of oriented in the s-states near resonance is considered separately

  2. A Miniature Laser Desorption/Ionization Time-of-Flight Mass Spectrometer for in Situ Analysis of Mars Surface Composition and Identification of Hazard in Advance of Future Manned Exploration

    Science.gov (United States)

    Getty, S. A.; Brinckerhoff, W. B.; Arevalo, R. D.; Floyd, M. M.; Li, X.; Cornish, T.; Ecelberger, S. A.

    2012-01-01

    Future landed missions to Mars will be guided by two strategic directions: (1) sample return to Earth, for comprehensive compositional analyses, as recommended by the 2011 NRC Planetary Decadal Survey; and (2) preparation for human exploration in the 2030s and beyond, as laid out by US space policy. The resultant mission architecture will likely require high-fidelity in situ chemical/organic sample analyses within an extremely constrained resource envelope. Both science goals (e.g., MEPAG Goal 1, return sample selection, etc.) as well as identification of any potential toxic and biological hazards to humans, must be addressed. Over the past several years of instrument development, we have found that the adaptable, compact, and highly capable technique of laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) has significant potential to contribute substantially to these dual objectives. This concept thus addresses Challenge Area 1: instrumentation and Investigation Approaches.

  3. Advances in photovoltaic technology

    Science.gov (United States)

    Landis, G. A.; Bailey, S. G.

    1992-01-01

    The advances in solar cell efficiency, radiation tolerance, and cost in the last 10 years are presented. The potential performance of thin-film solar cells in space is examined, and the cost and the historical trends in production capability of the photovoltaics industry are considered with respect to the needs of satellite solar power systems. Attention is given to single-crystal cells, concentrator and cascade cells, and thin-film solar cells.

  4. Gridded electron reversal ionizer

    Science.gov (United States)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  5. Gridded ionization chamber

    International Nuclear Information System (INIS)

    An improved ionization chamber type x-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is disposed adjacent the anode and is maintained at a voltsge intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting toward the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  6. Tevatron ionization profile monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, A.; Bowie, K.; Fitzpatrick, T.; Kwarciany, R.; Lundberg, C.; Slimmer, D.; Valerio, L.; Zagel, J.; /Fermilab

    2006-06-01

    Ionization Profile monitors have been used in almost all machines at Fermilab. However, the Tevatron presents some particular challenges with its two counter-rotating, small beams, and stringent vacuum requirements. In order to obtain adequate beam size accuracy with the small signals available, custom made electronics from particle physics experiments was employed. This provides a fast (single bunch) and dead-timeless charge integration with a sensitivity in the femto-Coulomb range, bringing the system close to the single ionization electron detection threshold. The detector itself is based on a previous Main Injector prototype, albeit with many modifications and improvements. The first detector was installed at the end of 2005, and the second detector during the spring shutdown. The ultimate goal is to continuously monitor beam size oscillations at injection, as well as the beam size evolution during ramp and squeeze. Initial results are very encouraging.

  7. Epidemiology and ionizing radiations

    International Nuclear Information System (INIS)

    The ionizing radiations have effects on living being. The determinist effects appear since a threshold of absorbed dose of radiation is reached. In return, the stochastic effects of ionizing radiations are these ones whom apparition cannot be described except in terms of probabilities. They are in one hand, cancers and leukemia, on the other hand, lesions of the genome potentially transmissible to the descendants. That is why epidemiology, defined by specialists as the science that studies the frequency and distribution of illness in time and space, the contribution of factors that determine this frequency and this distribution among human populations. This issue gathers and synthesizes the knowledge and examines the difficulties of methodologies. It allows to give its true place to epidemiology. (N.C.)

  8. Physics of ionized gases

    CERN Document Server

    Smirnov, Boris M

    2001-01-01

    A comprehensive textbook and reference for the study of the physics of ionized gasesThe intent of this book is to provide deep physical insight into the behavior of gases containing atoms and molecules from which one or more electrons have been ionized. The study of these so-called plasmas begins with an overview of plasmas as they are found in nature and created in the laboratory. This serves as a prelude to a comprehensive study of plasmas, beginning with low temperature and "ideal" plasmas and extending to radiation and particle transport phenomena, the response of plasmas to external fields, and an insightful treatment of plasma waves, plasma instabilities, nonlinear phenomena in plasmas, and the study of plasma interactions with surfaces

  9. Attosecond ionization dynamics

    International Nuclear Information System (INIS)

    Complete test of publication follows. In the interaction between light and matter, the central energy and bandwidth of the radiation, in relation to the energy structure of the studied atoms or molecules, are important parameters. Extreme ultraviolet attosecond pulses, produced through high-order harmonic generation, have during the last years been increasingly used for such studies, particularly in combination with intense infrared (IR) fields, for time-resolved studies of strong field processes. Attosecond experiments have so far utilized pulses with high central energies, in excess of the ionization, potentials of the studied species. When these pulses interact with matter they induce single-photon ionization, creating electron wave packets with a significant initial energy. In the present work, we have generated attosecond pulse trains in xenon, with individual pulse durations of 370 as. Their central energy is 23 eV, which is above the ionization potential of argon (15.8 eV) and neon (21.6 eV), but below that of helium (24.6 eV). We let these pulses interact with the target gas in the presence of a strong IR laser pulse, and measure the on yield as a function of the phase of the IR field at the time of arrival of the pulse. For helium, where the central energy of the pulses is below the ionization threshold, we find a significant enhancement of the ion yield when the IR field is present. In addition, the ion yield exhibits a sub-cycle modulation as a function of the IR phase. The origin of these effects can be understood through the measured photoelectron momentum distributions, and is confirmed by theoretical calculations based on the integration of the time-dependent Schroedinger equation.

  10. Gridded Ionization Chamber

    International Nuclear Information System (INIS)

    In the present paper the working principles of a gridded ionization chamber are given, and all the different factors that determine its resolution power are analyzed in detail. One of these devices, built in the Physics Division of the JEN and designed specially for use in measurements of alpha spectroscopy, is described. finally the main applications, in which the chamber can be used, are shown. (Author) 17 refs

  11. Ionization by nuclear transitions

    International Nuclear Information System (INIS)

    A phenomenological description of ionization events is given that applies to both shaking transitions of the composite nucleus-atom system and the process in which the charged particles emitted in a nuclear decay transfer energy by a relatively slow ''direct collision'' final state interaction with atomic electrons. Specific areas covered include shakeoff in internal conversion, shakeoff in electron capture, shakeoff in beta decay, and inner electron ejection in alpha decay. (5 figs., 1 table)

  12. Application of ionizing radiations

    International Nuclear Information System (INIS)

    The main subject of the application of Ionizing Radiations Program is to disseminate and consolidate techniques leading to the use of the radiation technology and radioisotopes application in Industry, Human Health, Agriculture and Environmental Preservation. This Program is divided into four subprograms: 1) Food and Agricultural Products Irradiation; 2) Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; Radioactive Facilities and Equipment for Nuclear Techniques Applications

  13. Electrospray Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Ryan T.; Marginean, Ioan; Tang, Keqi

    2014-06-13

    Electrospray Ionization (ESI) is a process whereby gas phase ions are created from molecules in solution. As a solution exits a narrow tube in the presence of a strong electric field, an aerosol of charged droplets are is formed that produces gas phase ions as they it desolvates. ESI-MS comprises the creation of ions by ESI and the determination of their mass to charge ratio (m/z) by MS.

  14. Effects of ionizing radiation

    International Nuclear Information System (INIS)

    Starting with a brief introduction to radiation protection, the report gives an overview of exposure to ionising radiation in Belgium due to activities in relation to the nuclear fuel cycle, processing and disposal of radioactive waste and other artificial or natural sources. Where appropriate, the Belgian situation discussed from an international perspective. The radiological impact of reprocessing and non-reprocessing are compared. The biological effects of ionizing radiation, epidemiological studies as well as surveillance programmes on the Belgian territory are reported on

  15. Pregnancy and ionizing radiation

    International Nuclear Information System (INIS)

    Full text: In this report there will be presented the effects of ionizing radiation at the fetus and the necessary radioprotection. The biological results on the fetus, caused by the irradiation, depend on the dose of ionizing radiation that it receives and the phase of its evolution. The imminent effects of the irradiation can cause the fetus death, abnormalities and mental retardation, which are the result of overdose. The effects are carcinogenesis and leukemia, which are relative to the acceptable irradiating dose at the fetus and accounts about 0,015 % per 1 mSv. The effects of ionizing radiation depend on the phase of the fetus evolution: 1st phase (1st - 2nd week): presence of low danger; 2nd phase (3rd - 8th week): for doses >100 mSv there is the possibility of dysplasia; 3rd phase (8th week - birth): this phase concerns the results with a percentage 0,015 % per 1 mSv. We always must follow some rules of radioprotection and especially at Classical radiation use of necessary protocols (low dose), at Nuclear Medicine use of the right radioisotope and the relative field of irradiation for the protection of the adjacent healthy tissues and at Radiotherapy extreme caution is required regarding the dose and the treatment. In any case, it is forbidden to end a pregnancy when the pregnant undergoes medical exams, in which the uterus is in the beam of irradiation. The radiographer must always discuss the possibility of pregnancy. (author)

  16. Dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    The book informs of the whole range of the physical foundations of dosimetry. In the chapter dealing with the interaction of ionizing radiation with matter the processes are described of the interaction between the individual types of ionizing radiation and matter and the effects of ionizing radiation on matter. The chapter dealing with dosimetric quantities and units gives a survey and definitions of quantities and their inter-relations. The chapters relating to the determination of basic dosimetric quantities and to integral dosimetric methods give a detailed description of the individual methods. The chapter relating to radionuclides in the environment concerns the occurrence of natural radionuclides in the environment and in the human organism, cosmic radiation and artificial sources of radioactivity connected with the development of civilisation and technology. The chapter related to radiation protection gives guidelines for the calculation of shielding for individual types of radiation. The supplement contains a list of the properties of certain radionuclides widespread in the environment, their basic physico-chemical and biological characteristics, parameters of metabolism and values of maximum permissible concentrations. (M.D.)

  17. Non-ionizing radiation

    International Nuclear Information System (INIS)

    The still growing use of non-ionizing radiation such as ultraviolet radiation laser light, ultrasound and infrasound, has induced growing interest in the effects of these types of radiation on the human organism, and in probable hazards emanating from their application. As there are up to now no generally approved regulations or standards governing the use of non-ionizing radiation and the prevention of damage, it is up to the manufacturers of the relevant equipment to provide for safety in the use of their apparatus. This situation has led to a feeling of incertainty among manufacturers, as to how which kind of damage should be avoided. Practice has shown that there is a demand for guidelines stating limiting values, for measuring techniques clearly indicating safety thresholds, and for safety rules providing for safe handling. The task group 'Non-ionizing radiation' of the Radiation Protection Association started a programme to fulfill this task. Experts interested in this work have been invited to exchange their knowledge and experience in this field, and a collection of loose leaves will soon be published giving information and recommendations. (orig./HP)

  18. Laser desorption/ionization mass spectrometry on nanostructured semiconductor substrates: DIOS(TM) and QuickMass(TM)

    Science.gov (United States)

    Law, K. P.

    2010-02-01

    In the era of systems biology, new analytical platforms are under demand. Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a promising high throughput laser mass spectrometry approach that has attracted a lot of attention, and has been commercialized. Another substrate material manufactured by physical method has also been made commercially available under the trade name of QuickMass(TM). These two commercial substrates, DIOS(TM) and QuickMass(TM), were investigated independently from the manufacturers and were characterized by a number of advanced surface techniques. This work determined (1) the correlation between the substrate physicochemical properties and their LDI activity, (2) the feasibility of metabolic profiling from complex biological matrices and (3) the laser desorption/ionization mechanism. The DIOS(TM) substrate was characterized with a thick nano-sized porous layer, a high surface concentration of fluorocarbon and silicon oxides and super-hydrophobicity. In contrast, the QuickMass(TM) substrate consisted of a non-porous germanium thin-film. The relatively high ionization efficiency obtained from the DIOS(TM) substrate was contributed to the fluorosilane manufacturing processes and its porous morphology. Despite the QuickMass(TM) substrate being less effective, it was noted that the use of germanium affords a self-cleaning mechanism and suppresses background interference of mass spectra. The suitability of DIOS(TM) substrates for metabolic profiling of complex biological matrices was demonstrated. DIOS mass spectra of human blood plasma, human urine and animal liver tissue extracts were produced. Suitable extraction methods were found to be important, but relatively simplified approaches were sufficient. Further investigations of the DIOS desorption/ionization mechanism were carried out. The previously proposed sub-surface state reaction could be a molten-solid interfacial state reaction of the substrate and this had a significant

  19. Epicyclic helical channels for parametric resonance ionization cooling

    Energy Technology Data Exchange (ETDEWEB)

    Johson, Rolland Paul [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav [Muons, Inc., Batavia, IL (United States)

    2015-08-23

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

  20. Asymmetric Magnetic Reconnection in Weakly Ionized Chromospheric Plasmas

    CERN Document Server

    Murphy, Nicholas A

    2015-01-01

    Realistic models of magnetic reconnection in the solar chromosphere must take into account that the plasma is partially ionized and that plasma conditions within any two magnetic flux bundles undergoing reconnection may not be the same. Asymmetric reconnection in the chromosphere may occur when newly emerged flux interacts with pre-existing, overlying flux. We present 2.5D simulations of asymmetric reconnection in weakly ionized, reacting plasmas where the magnetic field strengths, ion and neutral densities, and temperatures are different in each upstream region. The plasma and neutral components are evolved separately to allow non-equilibrium ionization. As in previous simulations of chromospheric reconnection, the current sheet thins to the scale of the neutral-ion mean free path and the ion and neutral outflows are strongly coupled. However, the ion and neutral inflows are asymmetrically decoupled. In cases with magnetic asymmetry, a net flow of neutrals through the current sheet from the weak field (high ...

  1. Ionized helium afterglow study

    International Nuclear Information System (INIS)

    In order to take into account the characteristics of ionized helium, under relaxation conditions, in the determination of the unknown coefficients of the reaction rates and more particularly those of the recombination of H2+ ions, a method has been developed which consists in recovering, using a system of differential equations with coupled partial derivatives, the set of all the physical quantities which can at the moment be measured as a function of time in a helium after-discharge. The energy balance of the maxwellian electrons and the speed distribution function of the electrons were studied in details and calculated as a function of time and location in space. The non-maxwellian electrons were included in the calculations. Measurements were made over a large range of experimental conditions using 5 different diagnoses: UHF interferometry in the X band, UHF radiometry in the X band, mass spectrometry, optical absorption spectrometry and optical emission spectrometry. All experimental data, obtained at 293 deg K and at seven different pressures ranging from 5 to 100 Torr were perfectly reproduced by the proposed system of differential equations, with the same reaction rate coefficients and the same constants. The method developed here gives a complete solution for the helium after-discharge at room temperature over a wide range of experimental conditions. It underlines the important reactions within the ionized gas, gives the absolute value and the dependences of the electron-He2+ ion recombination coefficient and allows the determination of the elementary mechanisms causing these dependences. It also gives the coefficients and the reaction rates of all the other elementary mechanisms which, besides recombination, determine the relaxation of ionized helium

  2. Resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    The subject of resonance ionization spectroscopy (RIS) from its inception to the present is summarized. The uses of RIS are principally analytical, and these uses are classified in several different ways for this report. The classifications are: (1) basic ways of counting atoms; (2) RIS applications according to the type of particle detector; (3) applications according to source preparation; (4) applications in chemical physics and chemistry; and (5) applications involving daughter atom detection. Each classification is discussed in some detail, and examples of specific applications are mentioned under each classification. Some other potential applications not necessarily related to these classifications are also mentioned

  3. Thin films

    International Nuclear Information System (INIS)

    This volume is a compilation of papers presented at the 1990 Spring Meeting of the Materials Research Society in a symposium entitled Thin Films: Stresses and Mechanical Properties II. As indicated by the title, the symposium was the second in a series, the first of which was held at the Fall Meeting in 1988. The importance of thin film mechanical properties is now recognized to the extent that basic characterization techniques such as microindentation and thin film stress measurement are performed routinely, and new characterization techniques are being developed on a daily basis. Many of the papers in the symposium dealt with the developments in these characterization methods and their application to a broad spectrum of materials such as compositionally modulated structures, ion implanted materials, optical coatings, and the numerous metals, ceramics and organics used in semiconductor device manufacture

  4. Thin Places

    OpenAIRE

    Lockwood, Sandra Elizabeth

    2013-01-01

    This inquiry into the three great quests of the twentieth century–the South Pole, Mount Everest, and the Moon–examines our motivations to venture into these sublime, yet life-taking places. The Thin Place was once the destination of the religious pilgrim seeking transcendence in an extreme environment. In our age, the Thin Place quest has morphed into a challenge to evolve beyond the confines of our own physiology; through human ingenuity and invention, we reach places not meant to accommod...

  5. Recent advances of nanodosimetry.

    Science.gov (United States)

    Grosswendt, B

    2004-01-01

    The early damage to genes and cells due to ionizing radiation is initiated by the overlay of the track structure of charged particles and of the structure of radiosensitive sub-cellular volumes. As a result of this overlay, a specified number of ionizations (the ionization cluster size) is formed per primary particle. Therefore, one of the aims of nanodosimetry is to determine ionization cluster-size distributions in nanometric volumes of liquid water, as a substitute to sub-cellular structures. After a short description of the main aspects of cluster-size formation by charged particles, an overview of the advanced measuring techniques that use millimetric target volumes filled with a low-pressure gas to simulate nanometric target volumes at unit density is given. Afterwards, physical principles are discussed which are applicable to convert ionization cluster-size distributions measured in gases into those for liquid water. Finally, a tentative possibility is proposed of how to relate parameters derived from cluster-size distributions in liquid water to parameters derived from radiation-induced radiobiological experiments. PMID:15353748

  6. Recent advances of nanodosimetry

    International Nuclear Information System (INIS)

    The early damage to genes and cells due to ionizing radiation is initiated by the overlay of the track structure of charged particles and of the structure of radiosensitive sub-cellular volumes. As a result of this overlay, a specified number of ionizations (the ionization cluster size) is formed per primary particle. Therefore, one of the aims of nanodosimetry is to determine ionization cluster-size distributions in nano-metric volumes of liquid water, as a substitute to sub-cellular structures. After a short description of the main aspects of cluster-size formation by charged particles, an overview of the advanced measuring techniques that use millimetric target volumes filled with a low-pressure gas to simulate nano-metric target volumes at unit density is given. Afterwards, physical principles are discussed which are applicable to convert ionization cluster-size distributions measured in gases into those for liquid water. Finally, a tentative possibility is proposed of how to relate parameters derived from cluster-size distributions in liquid water to parameters derived from radiation-induced radiobiological experiments. (authors)

  7. Ionizing radiation and occupational risks

    International Nuclear Information System (INIS)

    This brochure gives information about the risks of working with ionizing radiation. It tries to give answers to frequently posed questions, like; what is ionizing radiation; what are the biological consequences; which are the juridicial rules for inspection and control in the Netherlands. The auditory of the publication is thought to be: radiological workers, or employees working in the neighbourhood of ionizing radiation sources, radiation experts, safety experts and medical officers. (Auth.)

  8. A marginal theory for critical velocity ionization

    International Nuclear Information System (INIS)

    All space based tests of Alfven's CIV hypothesis to date may be described as marginal. That is, no large excess of ionization has been observed, but in many experiments, such as Porcupine, the observed ionization seems to exceed that which can be explained by charge exchange and other collisional processes. This talk will advance the theory that the coupling of momentum to the background plasma by new born ions is more limited than previously thought, and that this limiting will restrict the build up of excess ion density at any point in space. One may generalize CIV theory to state that the free energy available for transfer from new born ions to electrons and subsequently available for additional ionization, depends on the relative velocity between the ions and electrons bound to the magnetic. It will be shown that maintaining the highest possible relative velocity depends on coupling the momentum of new ions to the ambient plasma. It will also be argued that the ambient thermal current places more severe limits on momentum coupling than generally allowed by MHD

  9. Thin book

    DEFF Research Database (Denmark)

    En lille bog om teater og organisationer, med bidrag fra 19 teoretikere og praktikere, der deltog i en "Thin Book Summit" i Danmark i 2005. Bogen bidrager med en state-of-the-art antologi om forskellige former for samarbejde imellem teater og organisationer. Bogen fokuserer både på muligheder og...

  10. Thin Films

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga

    Maribor: Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * thin films * nannomaterials Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  11. Pixelized Gas Micro-well Detectors for Advanced Gamma-ray Telescopes

    CERN Document Server

    Bloser, P F

    2004-01-01

    We describe possible applications of pixelized micro-well detectors (PMWDs) as three-dimensional charged particle trackers in advanced gamma-ray telescope concepts. A micro-well detector consists of an array of individual micro-patterned gas proportional counters opposite a planar drift electrode. When combined with pixelized thin film transistor (TFT) array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this technique is the very low scattering that the charged particles experience in a gas tracking volume, and the very accurate determination of the initial particle momenta that is thus achieved. We consider two applications of PMWDs to gamma-ray astronomy: 1) A tracker for an Advanced Compton Telescope (ACT) in which the recoil electron from the initial Compton scatter may be accurately tracked, greatly reducing the telescope's point spread f...

  12. Time-resolved measurements of the ionization front in transport studies

    International Nuclear Information System (INIS)

    Characterization of the ionization front associated with thermal transport in laser-irradiated CH targets, as measured by x-ray emission from imbedded thin metallic layers, will be discussed. Observations of time-resolved filter spectrometry and time-integrated crystal spectroscopy of continuum and line emission from targets uniformly irradiated by the 24-beam 1053 nm and 6-beam 351 nm OMEGA laser will be compared, and contrasted with LTE calculations from the code LILAC; in particular, thin layer experiments suggest an observable competition between rates of ionization and hydrodynamic expansion

  13. Complex surfaces plated by thin-film deposition in one operation

    Science.gov (United States)

    Buckley, D. H.; Przybyszewski, J. S.; Spalvins, T.

    1967-01-01

    Ion plating deposits thin film on complex surface in one operation. The ionized materials follow electric lines of force to all points on the objects, uniformly plating the surface from all sides simultaneously.

  14. Multiphoton ionization of Uracil

    Science.gov (United States)

    Prieto, Eladio; Martinez, Denhi; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2016-05-01

    Multiphoton ionization and dissociation of Uracil using a Reflectron time of flight spectrometer was performed along with radiation from the second harmonic of a Nd:YAG laser. Uracil is one of the four nitrogen bases that belong to RNA. The last years special interest has been concentrated on the study of the effects under UV radiation in nucleic acids1 and also in the role that this molecule could have played in the origin and development of life on our planet.2 The MPI mass spectra show that the presence and intensity of the resulting ions strongly depend on the density power. The identification of the ions in the mass spectra is presented. The results are compared with those obtained in other laboratories under different experimental conditions and some of them show partial agreement.3 The present work was supported by CONACYT-Mexico Grant 165410 and DGAPA UNAM Grant IN101215 and IN102613.

  15. Applications of ionizing radiations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-07-01

    Developments in standard applications and brand new nuclear technologies, with high impact on the future of the agriculture, medicine, industry and the environmental preservation. The Radiation Technology Center (CTR) mission is to apply the radiation and radioisotope technologies in Industry, Health, Agriculture, and Environmental Protection, expanding the scientific knowledge, improving human power resources, transferring technology, generating products and offering services for the Brazilian society. The CTR main R and D activities are in consonance with the IPEN Director Plan (2011-2013) and the Applications of Ionizing Radiation Program, with four subprograms: Irradiation of Food and Agricultural Products; Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; and Radioactive Facilities and Equipment for the Applications of Nuclear Techniques.

  16. Applications of ionizing radiations

    International Nuclear Information System (INIS)

    Developments in standard applications and brand new nuclear technologies, with high impact on the future of the agriculture, medicine, industry and the environmental preservation. The Radiation Technology Center (CTR) mission is to apply the radiation and radioisotope technologies in Industry, Health, Agriculture, and Environmental Protection, expanding the scientific knowledge, improving human power resources, transferring technology, generating products and offering services for the Brazilian society. The CTR main R and D activities are in consonance with the IPEN Director Plan (2011-2013) and the Applications of Ionizing Radiation Program, with four subprograms: Irradiation of Food and Agricultural Products; Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; and Radioactive Facilities and Equipment for the Applications of Nuclear Techniques

  17. Food ionizing treatment

    International Nuclear Information System (INIS)

    Treatment of food with ionizing radiation is increasingly being recognized as a means of reducing food-borne illnesses and associated medical and other costs. In addition, the process may contribute to food security by preventing post-harvest losses, thereby making more food available to more people, eventually at lower cost. An ever increasing number of countries has approved the irradiation of a long and growing list of different food items, groups of classes, ranging from spices to grains to fruit and vegetables to meats and poultry and seafood. However, perception by consumers has been controversial and concerns have been expressed, particularly related to the safety of irradiated food. Therefore, the toxicological aspects of irradiated food are addressed in this dossier. It should be recognized that food irradiation is perhaps the most thoroughly investigated food processing technology. According to the World Health Organization 'irradiated food produced in accordance with established Good Manufacturing Practice can be considered safe and nutritionally adequate'. A recent evaluation by a WHO/FAO/IAEA study group (Geneva, Sept. 1997) even came to the conclusion, 'that as long as sensory qualities of food are retained and harmful microorganisms are destroyed, the actual amount of ionizing radiation applied is of secondary consideration'. Thus, also treatment of food with doses greater than the currently recommended upper level of 10 kGy by the Codex Alimentarius Commission will not lead to changes in the composition of the food that, from a toxicological point of view, would have an adverse effect on human health. (author)

  18. Testing a ring-shaped ionization chamber in standard beta radiation

    International Nuclear Information System (INIS)

    A ring-shaped ionization chamber, developed at Instituto de Pesquisas Energeticas e Nucleares, was tested in standard beta radiation fields. This ionization chamber was primarily developed to be used as a monitor chamber in X-ray diagnostic radiology beams. It has a large sensitive volume and parallel-plate aluminium electrode. Its entrance window is made of a thin aluminized polyester foil, which allows the collection of electrons. The ring-shaped monitor chamber was already tested in X radiation beams, showing a good performance. The aim of this work was to verify the applicability of the ionization chamber for beta radiation field dosimetry at calibration distances. (author)

  19. On ionization energy losses of ultra-relativistic half-bare electron

    Science.gov (United States)

    Shul'ga, N. F.; Trofymenko, S. V.

    2012-11-01

    The problem of ionization energy losses of relativistic electron after its emission from substance into vacuum and subsequent traversal of thin dielectric plate is considered. It is shown that with the increase of distance between the plate and the substance the gradual increase of electron ionization energy losses in the plate from the value defined by Fermi formula to the value defined by Bethe-Bloch formula complemented by radiation contribution to ionization occurs. It is highlighted that such change of energy losses is defined by reconstruction of the field around the electron and may occur on macroscopic distances along its trajectory.

  20. Ionization detection system for aerosols

    Science.gov (United States)

    Jacobs, Martin E.

    1977-01-01

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber.

  1. Advanced Structural Characterization of Organic Thin Films

    DEFF Research Database (Denmark)

    Gu, Yun

    of small molecule and polymer layers is indicated by Flory- Huggins theory for the triisopropylsilylethynl pentacene (TIPS-PEN) and polystyrene blend films. In order to investigate the phase separated layers in the ink-jet printed films, we propose a method to measure diraction Bragg peaks by X...

  2. High pressure xenon ionization detector

    International Nuclear Information System (INIS)

    A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs

  3. Ionization box type radiation detector

    International Nuclear Information System (INIS)

    An ionization box for monitoring radiation rays, a first amplification circuit of a multi-stage amplification circuit employing a MOS type FET as an initial stage amplification device, a second amplification circuit employing a junction type FET as an initial stage amplification device, a first change-over switch for switching ionization current depending on input signals, a second change-over switch for switching output signals, and a signal level discrimination circuit are constituted integrally. When radiation dose rate is low, the ionization current is inputted to the first amplification circuit and outputted as a radiation ray monitor signal and, when the radiation dose rate is increased to higher than a predetermined value, the ionization current is inputted to the second amplification circuit and outputted as a radiation ray monitor signal. That is, monitoring accuracy is high when the ionization current is low since the MOS type FET of high input impedance is used. If the ionization current is higher than a predetermined value, there is no worry that the detection becomes impossible since the junction type FET having less worry of causing characteristic change due to high radiation dose rate is used. Accordingly, ionization box type monitor at a high monitoring reliability can be obtained. (N.H.)

  4. Optical ionization detector

    Science.gov (United States)

    Wuest, Craig R.; Lowry, Mark E.

    1994-01-01

    An optical ionization detector wherein a beam of light is split so that one arm passes through a fiber optics and the other arm passes through a gas-filled region, and uses interferometry to detect density changes in a gas when charged particles pass through it. The gas-filled region of the detector is subjected to a high electric field and as a charged particle traverses this gas region electrons are freed from the cathode and accelerated so as to generate an electron avalanche which is collected on the anode. The gas density is effected by the electron avalanche formation and if the index or refraction is proportional to the gas density the index will change accordingly. The detector uses this index change by modulating the one arm of the split light beam passing through the gas, with respect to the other arm that is passed through the fiber optic. Upon recombining of the beams, interference fringe changes as a function of the index change indicates the passage of charged particles through the gaseous medium.

  5. Ionization in liquids

    International Nuclear Information System (INIS)

    During the 1987--1990 reporting period, studies were conducted that entailed the direct measurement of the transport and reaction properties of excess electrons in nonpolar liquids through the use of pulse-conductivity techniques. The results obtained from these studies should be applicable toward the development of a better understanding of the primary ionizing event in liquids as well as to providing physico-chemical information that is pertinent to electron-transfer processes that are ubiquitous in biological systems. Progress was also made in developing a better understanding of electron attachment reactions in liquids through measurements of the electron attachment rate constants, kes, of a variety of electron-attaching solutes. The effects of several functional groups substituted at different positions on benzene were studied in liquid cyclohexane and isooctane. The electron-attaching properties of chemicals having well characterized carcinogenic properties were studied in cyclohexane to determine if the measure of electron-accepting potential that ke provides can elucidate the role that electrons play in the initiation step of carcinogenesis. The kes that were measured indicate that the ke-carcinogenicity correlation that was observed can be used to complement short-term carcinogen-screening bioassays to identify potential carcinogens. 115 refs., 6 tabs

  6. Effects of ionizing radiation

    International Nuclear Information System (INIS)

    A sound evaluation of the consequences of releases of radioactivity into the environment, especially of those large amounts, and of the effectiveness of different protective measures, requires thorough concern of the various aspects of the radiological effects. The effects of ionizing radiation were reviewed according to the following characterization: Affected subject (somatic, genetic and psychological effects); Duration of irradiation (acute and chronic irradiation); Latent period (early and late effects); Dose-effect relationship (stochastic and non-stochastic effects); Population affected (e.g. children, pregnant women). In addition to the lethal effects which are generally considered extensively in all the evaluations of the consequences of radioactivity releases, such effects as early symptoms and morbidity are emphasized in this review. The dependence of the effects on dose rates, repair mechanism and medical treatment is discussed, and the uncertainties involved with their evaluation is highlighted. The differences between QF (quality factor) and RBE (relative biological effectiveness) of different radiation sources are interpreted. Synergystic effects and the effectiveness of various means of medication are discussed. It is suggested that all radiological effects, including those resulting from relatively low radiation doses, e.g. foetus deformations, fertility impairment, prodomal - leading to psychological effects, should be considered within the evaluation of the consequences of radioactivity releases and of the effectiveness of protective measures. Limits of the repair factors to be considered within the evaluation of the effects of chronic exposures are proposed

  7. Photoionization effects in ionization fronts

    Energy Technology Data Exchange (ETDEWEB)

    Arrayas, Manuel [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Fontelos, Marco A [Departamento de Matematicas, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones CientIficas, C/Serrano 123, 28006 Madrid (Spain); Trueba, Jose L [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)

    2006-12-21

    In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work.

  8. Ionization-based detectors for gas chromatography.

    Science.gov (United States)

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. PMID:25757823

  9. Theory of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Resonance Ionization Spectroscopy (RIS) can be defined as a state selective detection process in which pulsed tunable lasers are used to promote transitions from the selected state of the atoms or molecules in question to higher states, one of which will be ionized by the absorption of another photon. At least one resonance step is used in the stepwise ionization process, and it has been shown that the ionization probability of the spectroscopically selected species can nearly always be made close to unity. Since measurements of the number of photoelectrons or ions can be made very precisely and even one electron (or under vacuum conditions, one ion) can be detected, the technique can be used to make quantitative measurements of very small populations of the state-selected species

  10. Calculation of multiphoton ionization processes

    Science.gov (United States)

    Chang, T. N.; Poe, R. T.

    1976-01-01

    We propose an accurate and efficient procedure in the calculation of multiphoton ionization processes. In addition to the calculational advantage, this procedure also enables us to study the relative contributions of the resonant and nonresonant intermediate states.

  11. Strong Ionization in carbon Nanowires

    CERN Document Server

    Kaymak, Vural; Shlyaptsev, Vyacheslav N; Rocca, Jorge J

    2015-01-01

    Surfaces covered with nanostructures, such as nanowire arrays, have shown to facilitate a significantly higher absorption of laser energy as compared to flat surfaces. Due to the efficient coupling of the laser energy, highly energetic electrons are produced, which in turn can emit intense ultrafast X-ray pulses. In the present work we use full three dimensional PIC simulations to analyze the behavior of arrays of carbon nanowires $400 nm$ in diameter, irradiated by a $\\lambda_0 = 400 nm$ laser pulse of $60 fs$ duration at FWHM and a vector potential of $a_0 = 18$. We analyze the ionization dynamics of the nanowires. We investigate the difference of the ionization strength and structure between linearly and circularly polarized laser beam. The nanowires are found to be fully ionized after about 30 laser cycles. Circularly polarized light reveals a slightly stronger ionization effect.

  12. Resonance Ionization Laser Ion Sources

    CERN Document Server

    Marsh, B

    2013-01-01

    The application of the technique of laser resonance ionization to the production of singly charged ions at radioactive ion beam facilities is discussed. The ability to combine high efficiency and element selectivity makes a resonance ionization laser ion source (RILIS) an important component of many radioactive ion beam facilities. At CERN, for example, the RILIS is the most commonly used ion source of the ISOLDE facility, with a yearly operating time of up to 3000 hours. For some isotopes the RILIS can also be used as a fast and sensitive laser spectroscopy tool, provided that the spectral resolution is sufficiently high to reveal the influence of nuclear structure on the atomic spectra. This enables the study of nuclear properties of isotopes with production rates even lower than one ion per second and, in some cases, enables isomer selective ionization. The solutions available for the implementation of resonance laser ionization at radioactive ion beam facilities are summarized. Aspects such as the laser r...

  13. Resonance ionization for analytical spectroscopy

    Science.gov (United States)

    Hurst, George S.; Payne, Marvin G.; Wagner, Edward B.

    1976-01-01

    This invention relates to a method for the sensitive and selective analysis of an atomic or molecular component of a gas. According to this method, the desired neutral component is ionized by one or more resonance photon absorptions, and the resultant ions are measured in a sensitive counter. Numerous energy pathways are described for accomplishing the ionization including the use of one or two tunable pulsed dye lasers.

  14. Multi-chamber ionization detector

    International Nuclear Information System (INIS)

    For the detector a single beta ionization source and a double- or three-chamber set-up is used, the chambers being designed in the shape of a truncated cone and facing each other with their bases. The source can be positioned with respect to the common center or modal electrode, the adjustment of the ionization in each chamber this becoming easier. The center or modal electrode also can be adjusted with respect to the source. (DG)

  15. Multiphoton double ionization of barium

    International Nuclear Information System (INIS)

    The authors report the observation of the wavelength spectrum of the double ionization of Ba from ∼ 280 nm to nearly 700 nm, using laser pulses 5ns long of peak intensity ∼ 1010 W/cm2. All the strong resonances can be assigned to Ba+ transitions, and many of the assignments have been verified by pump-probe techniques. Thus, the Ba++ observed is due to sequential ionization. The shortest wavelengths used are not as effective as λ ∼ 500 nm

  16. CERI: Ionizing Radiation Calibration Centre

    International Nuclear Information System (INIS)

    The CERI has been granted by the National Bureau of Metrology (BNM) as an Ionizing Radiation Calibration Centre and as an Estimation and Qualification Centre for the ionizing radiation measurement devices. This article gives some information on the scope covered by the BNM's grant and on the various equipment on which the laboratory relies. It describes the calibration and estimation activities and mentions many kinds of services which are offered to the users mainly in the medical and industrial fields

  17. Laser ionization mass spectroscopy

    Science.gov (United States)

    Bernardez, Luis J., III; Siekhaus, W. J.

    1989-10-01

    Laser Ionization Mass Spectroscopy (LIMS) is a simple technique with several advantages and disadvantages over standard mass spectroscopy techniques. The LIMS technique uses a laser to vaporize a small portion of a sample. The vapor from the sample consists of a mixture of charged and neutral atoms or fragments. Using electrostatic grids, the ions (positive or negative) are given a known amount of kinetic energy and sent down a time-of-flight tube. The time it takes the ions to travel down the flight tube is recorded. Knowing the ions' energy, the length of the flight tube, and the time it takes the ions to travel that distance, the masses of the ions can be calculated. The instrument used is a LIMA 3 made by Cambridge Mass Spectrometry. It has a Quanta Ray DCR-11 Nd:YAG laser, which was frequency-quadrupled to 266 nm. The laser spot size is typically between 2 and 5 microns in diameter and the pulse width is between 5 and 10 nanoseconds. The energy of the laser is continually variable between 0.1 and 3.0 millijoules. The detector is a 17-stage venetian-blind multiplier made by Thorn EMI. The analysis is carried out under vacuum, usually between 10(exp -8) and 10(exp -9) Torr. The LIMA 3 has several useful features such as: a He-Ne pilot laser used to target the Nd:YAG laser; a microscope (which is used to view the sample through the laser optics); and a precision sample stage for accurate sample alignment.

  18. Synergistic effect of ozonation and ionizing radiation for PVA decomposition.

    Science.gov (United States)

    Sun, Weihua; Chen, Lujun; Zhang, Yongming; Wang, Jianlong

    2015-08-01

    Ozonation and ionizing radiation are both advanced oxidation processes (AOPs) without chemical addition and secondary pollution. Also, the two processes' efficiency is determined by different pH conditions, which creates more possibilities for their combination. Importantly, the combined process of ozonation and ionizing radiation could be suitable for treating wastewaters with extreme pH values, i.e., textile wastewater. To find synergistic effects, the combined process of ozonation and ionizing radiation mineralization was investigated for degradation of polyvinyl alcohol (PVA) at different pH levels. A synergistic effect was found at initial pH in the range 3.0-9.4. When the initial pH was 3.0, the combined process of ozonation and ionizing radiation gave a PVA mineralization degree of 17%. This was 2.7 times the sum achieved by the two individual processes, and factors of 2.1 and 1.7 were achieved at initial pH of 7.0 and 9.4, respectively. The combined process of ozonation and ionizing radiation was demonstrated to be a feasible strategy for treatment of PVA-containing wastewater. PMID:26257347

  19. INDUSTRIAL EFFLUENT TREATMENT USING IONIZING RADIATION COMBINED TO TITANIUM DIOXIDE

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, C.L.; Oikawa, H.; Mori, M.N.; Sampa, M.H.O.

    2004-10-04

    The Advanced Oxidation Process (AOP) with OH radicals are the most efficient to mineralize organic compounds, and there are various methods to generate OH radicals as the use of ozone, hydrogen peroxide and ultra-violet radiation and ionizing radiation. The irradiation of aqueous solutions with high-energy electrons results in the excitation and ionizing of the molecules and rapid (10{sup -14} - 10{sup -9} s) formation of reactive intermediates. These reactive species will react with organic compounds present in industrial effluent inducing their decomposition. Titanium dioxide (TiO{sub 2}) catalyzed photoreaction is used to remove a wide range of pollutants in air and water media, combined to UV/VIS light, FeO{sub 2}, and H{sub 2}O{sub 2}, but as far as known there is no report on the combination with ionizing radiation. In some recent studies, the removal of organic pollutants in industrial effluent, such as Benzene, Toluene, and Xylene from petroleum production using ionizing radiation was investigated. It has been ob served that none of the methods can be used individually in wastewater treatment applications with good economics and high degree of energy efficiency. In the present work, the efficiency of ionizing radiation in presence of TiO{sub 2} to treat industrial effluent was evaluated. The main aim to combine these technologies is to improve the efficiency for very hard effluents and to reduce the processing cost for future implementation to large-scale design.

  20. Parametric-Resonance Ionization Cooling of Muon Beams

    International Nuclear Information System (INIS)

    Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. Combining muon ionization cooling with parametric resonant dynamics should allow an order of magnitude smaller final equilibrium transverse beam emittances than conventional ionization cooling alone. In this scheme, a half-integer parametric resonance is induced in a cooling channel causing the beam to be naturally focused with the period of the channel's free oscillations. Thin absorbers placed at the focal points then cool the beam?s angular divergence through the usual ionization cooling mechanism where each absorber is followed by RF cavities. A special continuous-field twin-helix magnetic channel with correlated behavior of the horizontal and vertical betatron motions and dispersion was developed for PIC. We present the results of modeling PIC in such a channel using GEANT4/G4 beamline. We discuss the challenge of precise beam aberration control from one absorber to another over a wide angular spread

  1. Dynamic Reactive Ionization with Cluster Secondary Ion Mass Spectrometry

    Science.gov (United States)

    Tian, Hua; Wucher, Andreas; Winograd, Nicholas

    2016-02-01

    Gas cluster ion beams (GCIB) have been tuned to enhance secondary ion yields by doping small gas molecules such as CH4, CO2, and O2 into an Ar cluster projectile, Arn + ( n = 1000-10,000) to form a mixed cluster. The `tailored beam' has the potential to expand the application of secondary ion mass spectrometry for two- and three-dimensional molecular specific imaging. Here, we examine the possibility of further enhancing the ionization by doping HCl into the Ar cluster. Water deposited on the target surface facilitates the dissociation of HCl. This concerted effect, occurring only at the impact site of the cluster, arises since the HCl is chemically induced to ionize to H+ and Cl- , allowing improved protonation of neutral molecular species. This hypothesis is confirmed by depth profiling through a trehalose thin film exposed to D2O vapor, resulting in ~20-fold increase in protonated molecules. The results show that it is possible to dynamically maintain optimum ionization conditions during depth profiling by proper adjustment of the water vapor pressure. H-D exchange in the trehalose molecule M was monitored upon deposition of D2O on the target surface, leading to the observation of [Mn* + H]+ or [Mn* + D]+ ions, where n = 1-8 hydrogen atoms in the trehalose molecule M have been replaced by deuterium. In general, we discuss the role of surface chemistry and dynamic reactive ionization of organic molecules in increasing the secondary ion yield.

  2. Thin films and froth flotation

    International Nuclear Information System (INIS)

    The properties of thin, aqueous films on solid surfaces and their central role in the froth flotation process are discussed. The stability of these films can generally be described in terms of electrostatic and van der Waals forces. Significant experimental and theoretical advances are required in many areas (e.g. short range forces, film drainage) before a clear picture of the collision of, adhesion between and detachment of bubbles and particles will emerge. (orig.)

  3. MULTIPLE IONIZATION OF ATOMS THROUGH MULTIPHOTON ABSORPTION

    OpenAIRE

    L'Huillier, A

    1987-01-01

    We review the main aspects of multiple ionization of rare gases in strong laser fields (above 1012W.cm-2). We discuss the mechanisms responsible for the multi-electron ejection : inner-shell ionization or outer-shell ionization, one-step or multi-step. We show the differences between one-photon and multi-photon multiple ionization.

  4. Applications of thin-film photovoltaics for space

    Science.gov (United States)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The authors discuss the potential applications of thin-film polycrystalline and amorphous cells for space. There have been great advances in thin-film solar cells for terrestrial applications. Transfer of this technology to space applications could result in ultra low-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper indium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon arrays. The possibility of using thin-film multi-bandgap cascade solar cells is discussed.

  5. Thin-Film Photovoltaics: Status and Applications to Space Power

    Science.gov (United States)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

  6. Controlled-Resonant Surface Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

    2014-01-01

    This paper reports on the advancement of a controlled-resonance surface tapping-mode single capillary liquid junction extraction/ESI emitter for mass spectrometry imaging. The basic instrumental setup and the general operation of the system were discussed and optimized performance metrics were presented. The ability to spot sample, lane scan and chemically image in an automated and controlled fashion were demonstrated. Rapid, automated spot sampling was demonstrated for a variety of compound types including the cationic dye basic blue 7, the oligosaccharide cellopentaose, and the protein equine heart cytochrome c. The system was used for lane scanning and chemical imaging of the cationic dye crystal violet in inked lines on glass and for lipid distributions in mouse brain thin tissue sections. Imaging of the lipids in mouse brain tissue under optimized conditions provided a spatial resolution of approximately 35 m based on the ability to distinguish between features observed both in the optical and mass spectral chemical images. The sampling spatial resolution of this system was comparable to the best resolution that has been reported for other types of atmospheric pressure liquid extraction-based surface sampling/ionization techniques used for mass spectrometry imaging.

  7. Isotope separation with improved selective ionization

    International Nuclear Information System (INIS)

    Method and apparatus for isotope separation by selective ionization of a desired isotope in an environment of plural isotopes without corresponding ionization of the other isotopes in the environment. The selective ionization is achieved through a three step excitation of atoms of the desired isotope in response to laser radiations applied to the environment. The transition for each step is selected to be less than one half the ionization potential for the isotopes to avoid two step nonselective ionization

  8. Accelerated C-N Bond Formation in Dropcast Thin Films on Ambient Surfaces

    Science.gov (United States)

    Badu-Tawiah, Abraham K.; Campbell, Dahlia I.; Cooks, R. Graham

    2012-09-01

    The aza-Michael addition and the Mannich condensation occur in thin films deposited on ambient surfaces. The reagents for both C-N bond formation reactions were transferred onto the surface by drop-casting using a micropipette. The surface reactions were found to be much more efficient than the corresponding bulk solution-phase reactions performed on the same scale in the same acetonitrile solvent. The increase in rate of product formation in the thin film is attributed to solvent evaporation in the open air which results in reagent concentration and produces rate acceleration similar to that seen in evaporating droplets in desorption electrospray ionization. This thin film procedure has potential for the rapid synthesis of reaction products on a small scale, as well as allowing rapid derivatization of analytes to produce forms that are easily ionized by electrospray ionization. Analysis of the derivatized sample directly from the reaction surface through the use of desorption electrospray ionization is also demonstrated.

  9. One-atom detection in individual ionization tracks

    International Nuclear Information System (INIS)

    A major advance in one-atom detection using laser photoionization makes it possible to detect with microsecond time resolution single neutral atoms resulting from the stopping of energetic heavy ions in a buffer gas. This detection at the one-atom level, which gives the first direct evidence of nearly complete charge neutralization of stopped energetic ions, is shown to be possible even under the extremely adverse conditons associated with a densely ionized particle track

  10. 2.2.2 Non-Ionizing Radiations

    Science.gov (United States)

    Bernhardt, J. H.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.2.2 Non-Ionizing Radiations' of the Section '2.2 Kinds of Radiation' of the Chapter '2 Radiation and Biological Effects' with the contents:

  11. 2.3.1 Biological Effects of Ionizing Radiations

    Science.gov (United States)

    Kaul, A.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.3.1 Biological Effects of Ionizing Radiations' of the Section '2.3 Biological Effects' of the Chapter '2 Radiation and Biological Effects' with the comtents:

  12. Ambient ionization mass spectrometry: A tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

    2011-09-19

    Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

  13. Physics of thin films

    Energy Technology Data Exchange (ETDEWEB)

    Francombe, M.H. (Dept. of Physics, Univ. of Pittsburgh, Pittsburgh, PA (US)); Vossen, J.L. (John Vossen Associates, Technical and Scientific Consulting, Bridgewater, NJ (US))

    1992-01-01

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (T{sub c}) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-T{sub c} oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included.

  14. Physics of thin films

    International Nuclear Information System (INIS)

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (Tc) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-Tc oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included

  15. Amplification of critical velocity ionization by associative ionization

    International Nuclear Information System (INIS)

    Space experiments to verify the critical ionization velocity (CIV) theory have for the most part involved the release of barium in the ionosphere. It is suggested in this paper that associative ionization (Al) reactions involving barium (i.e., Ba + O → BaO + e) may occur in these experiments, and since the products would be indistinguishable from those generated by electron impact ionization (CIV), it is likely that AI-generated ions may be mistaken for those generated by CIV. The electrons formed in AI and by electron impact may be energized by the ion beams, generated by both CIV and AI. The energized electrons may ionize, enhancing the CIV process. In this way, the AI-CIV double process could amplify CIV. The amplification is especially important for sustaining CIV when the CIV energy budget is tight or when the ionization rate due to CIV alone is too low to satisfy Townsend's criterion. The result may have significant implications for the results observed in recent CIV space experiments using barium jets. The AI-CIV double process may offer a plausible explanation for the observed long distance of Ba+ ionization. Any other ion beam formation mechanism, such as charge exchange, stripping and reflected ambient ions, can also amplify CIV in a manner similar AI, although comparison of the relative magnitudes of several of these processes indicates that AI may be the most significant. The authors suggest an AI-assisted experiment in which a samarium beam could undergo AI, promoting CIV in an accompanying xenon beam

  16. Health effects of ionizing radiation

    International Nuclear Information System (INIS)

    Ionizing radiation is energy that travels through space as electromagnetic waves or a stream of fast moving particles. In the workplace, the sources of ionizing radiation are radioactive substances, nuclear power plants, x-ray machines and nuclear devices used in medicine, research and industry. Commonly encountered types of radiation are alpha particles, beta particles and gamma rays. Alpha particles have very little penetrating power and pose a risk only when the radioactive substance is deposited inside the body. Beta particles are more penetrating than alpha particles and can penetrate the outer body tissues causing damage to the skin and the eyes. Gamma rays are highly penetrating and can cause radiation damage to the whole body. The probability of radiation-induced disease depends on the accumulated amount of radiation dose. The main health effects of ionizing radiation are cancers in exposed persons and genetic disorders in the children, grandchildren and subsequent generations of the exposed parents. The fetus is highly sensitive to radiation-induced abnormalities. At high doses, radiation can cause cataracts in the eyes. There is no firm evidence that ionizing radiation causes premature aging. Radiation-induced sterility is highly unlikely for occupational doses. The data on the combined effect of ionizing radiation and other cancer-causing physical and chemical agents are inconclusive

  17. Models for multiphoton ionization processes

    International Nuclear Information System (INIS)

    Using the Fourier transform method, several analytical models for multiphoton processes have been developed, which emphasize the non-perturbative regime of C-C transitions. It was found that the population trapping of continuum-continuum (C-C) transitions can occurs under general conditions: for two continua with energy-dependent matrix elements, and for an infinite number of structureless continua with coupled bands. A above-threshold ionization model with two-frequency smooth pulses for hydrogenic atom was first proposed. This model give a simple form for analytical solutions if an ionization threshold is negligible. The results predict that (a) there is no trapping or saturation of the bound-continuum transition and that the ionization rate is independent of the redistribution among the continua for the C-C matrix element chosen; (b) There are peak switch in photoelectron energy spectra which depends on not only redistribution laser intensity, but also the pulses shape and their overlap in time, as well as the coupling between the bound state and continua; (c) peaks about the ionization energy in the photoelectron spectra are symmetric and only appear during the ionization process; (d) as the laser intensity is increased, the total angular photoelectrons distribution peak strongly in forward and backward direction of the redistribution laser polarization; and the minima of this distribution are not zero for higher laser intensity. The photon spectrum is also investigated

  18. L-SHELL IONIZATION MEASUREMENT OF TUNGSTEN BY ELECTRON IMPACT

    Institute of Scientific and Technical Information of China (English)

    PENG XIU-FENG; HE FU-QING; LONG XIAN-GUAN

    2000-01-01

    L-shell partial production cross sections of Lα- , Lβ-, Lγ- rays by electron impact were measured by observing the counts of X-ray from impacted thin tungsten target. Total production cross sections and mean ionization cross sections were deduced from these measured results. The electron beam energy range was from 11 to 36 keV. Tungsten was sputtered onto a carbon backing to reduce bremsstrahlung of the backing. The effect of electrons reflected by the backing has been corrected. Comparison with two theoretical calculations has performed. The experimental results agree rather well with the theoretical predications.

  19. Development and applications of ionization techniques in ambient mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Rejšek, Jan; Vrkoslav, Vladimír; Cvačka, Josef

    Prague : Charles University in Prague, Faculty of Science, 2014 - (Nesměrák, K.), s. 37-38 ISBN 978-80-7444-030-4. [International Students Conference "Modern Analytical Chemistry" /10./. Praha (CZ), 22.09.2014-23.09.2014] R&D Projects: GA ČR GAP206/12/0750 Grant ostatní: GA AV ČR(CZ) M200551204 Institutional support: RVO:61388963 Keywords : ambient mass spectrometry * desorption electrospray ionization * desorption atmospheric pressure photoionization * thin-layer chromatography * insect defense compounds * mass spectrometry imaging Subject RIV: CB - Analytical Chemistry, Separation

  20. High efficiency ionization chamber for fission experiments

    International Nuclear Information System (INIS)

    Complete text of publication follows. The width of fission fragment mass distribution indicates the number of di rent fragments which are produced during the fission process from a given excited state. Smaller width means more limited variety of fission fragments which can indicate clusterization effect in hyperdeformed states before fission and also means less amount of nuclear waste. A new gridded ionization chamber was constructed at Atomki to examine the mass distribution of the fission fragments from neutron induced fission of some U and Th isotopes. The design is based on a twin ionization chamber developed by C. Budtz-Jorgensen et al. Our aim was to increase the efficiency of the measurements by applying multiple detector units. This compound detector permits simultaneous measurement of the total kinetic energy and fission fragment emission angle with respect to the detector symmetry axis. The chamber consists of five twin parallel plate ionization chambers with Frisch grids. Assuming that at low counting rates only one target emits fission fragments in one event, the an- odes and the grids were interconnected form- ing two groups (A1-G1, A2-G2). In order to identify which target emitted the fission fragments the signals from each cathodes are also processed. The energy of the fission fragments is determined from the anode pulse heights, while the sum of the grid and anode signals is used to deduce the fragment emission angle θ with respect to the symmetry axis of the chamber: Qsum = -n0e[1 - (X/D)cosθ). The angle dependent energy losses in the tar get can be determined using this angular information. In order to minimize the distance between the targets and the neutron source, smaller distance between the plates and a smaller diameter had to be chosen as in Ref. This arrangement required higher gas pressure, which is necessary to stop the fission fragments before reaching the electrodes. A gas mixture of 90% Ar + 10% CH4 at 2 atm pressure was used. With a

  1. Atomic Ionization by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The field of atomic ionization by electron impact is several decades old. In that period of time, significant progress has been made in several aspects of the problem and we have learned a lot about ionizing collisions as a result of this work. Over the years, both the experiments and theories have improved dramatically. Experiments are now able to measure absolute triple differential cross sections for both in-plane or out-of-plane geometries. Theories have been getting better and better at including all the 3-body interactions in the wavefunction for the system. However, during the history of the field, experiment has been ahead of theory and it is just very recently that theory has started to catch up. In this paper, we will show that theory is now able to accurately predict the results of electron impact ionization of hydrogen for intermediate and higher energies.

  2. Magnetospheric critical ionization velocity experiment

    International Nuclear Information System (INIS)

    In March of 1983, a barium injection sounding rocket experiment (The Star of Lima) was conducted to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. Included in the instrumented payload was a UCSD particle-detection experiment consisting of five retarding-potential analyzers. Despite conditions that appeared to be optimal for the critical velocity effect, a fractional ionization of only approx.5 x 10-4 was observed, indicating that the conditions required for the effect to occur are still not well understood. Several possible explanations for this low ionization efficiency are explored. The most likely explanation for the negative result in the Star of Lima experiment is that the length of the cloud parallel to the magnetic field was smaller than the fastest growing modes of the lower hybrid instability believed to energize the electrons

  3. Theory of dissociative tunneling ionization

    CERN Document Server

    Svensmark, Jens; Madsen, Lars Bojer

    2016-01-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees freedom. In the regime where the BO approximation is applicable imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fiel...

  4. Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope

    CERN Document Server

    Bloser, P F; Ryan, J M; McConnell, M L; Miller, R S; Jackson, T N; Bai, B; Jung, S

    2004-01-01

    We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined from the drift time of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which ...

  5. Theory of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Resonance Ionization Spectroscopy (RIS) can be defined as a state selective detection process in which pulsed tunable lasers are used to promote transitions from the selected state of the atoms or molecules in question to higher states, one of which will be ionized by the absorption of another photon. The ability to make saturated RIS measurements opens up a wide variety of applications to both basic and applied research. In reviews of RIS the subject was treated generally, including the underlying photophysics applications, the ability to use it to count single atoms, and its applications to measurements in atomic and molecular physics. They view resonance ionization spectroscopy as a specific type of multiphoton ionization in which the goal is to make quantitative measurements of quantum-selected populations in atomic or molecular systems. This goal attained by requiring that the selective excitation steps be resonant in nature and involve only one- or two-photon (only one-photon if at all possible) absorption processes, thereby allowing the entire process to be carried to saturation without loss of spectroscopic selectivity due to laser power induced shifts or broadening

  6. Food irradiation with ionizing radiation

    International Nuclear Information System (INIS)

    Application possibilities are discussed of ionizing radiation in inhibiting plant germination, in radiopasteurization and radiosterilization of food. Also methods of combining radiation with thermal food sterilization are discussed. The problems of radiation doses and of hygienic purity of irradiated foodstuffs are dealt with. (B.S.)

  7. Negative chemical ionization mass spectrometry

    International Nuclear Information System (INIS)

    This thesis describes some aspects of Negative Chemical Ionization (NCI) mass spectrometry. The reasons for the growing interest in NCI are: (i) to extend the basic knowledge of negative ions and their reactions in the gas phase; (ii) to investigate whether or not this knowledge of negative ions can be used successfully to elucidate the structure of molecules by mass spectrometry. (Auth.)

  8. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

  9. Ionization Potentials for Isoelectronic Series.

    Science.gov (United States)

    Agmon, Noam

    1988-01-01

    Presents a quantitative treatment of ionization potentials of isoelectronic atoms. By looking at the single-electron view of calculating the total energy of an atom, trends in the screening and effective quantum number parameters are examined. Approaches the question of determining electron affinities. (CW)

  10. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak...

  11. Air ionization wire plane chamber

    International Nuclear Information System (INIS)

    Radiation Measurement for protection level instrumentation requires large number of detectors. Since the number is large, the detector should be cost effective and yet should have good sensitivity. Gas detectors with presently available microelectronics and signal processing capabilities opened a new era in radiation monitoring. Present paper describes the use of air filled multi anode grid planes as detector for alpha detection. Due to multiple anode wire planes, the charge collection efficiency of the air ionization chamber is higher as compared to conventional ionization chamber. The signal from this Wire Plane Chamber (WPC) has a faster and narrower pulse shape as compared to conventional two-electrode chamber of similar dimensions. The reduction in capacitance also improves the signal to noise ratio so that air can be used as the ionization medium without any special cleaning procedure etc and it may be possible to use even engineering plastic as the structural material for the chamber. The paper gives the results obtained so far with this air ionization chamber. (author)

  12. Biopositive Effects of Ionizing Radiation?

    International Nuclear Information System (INIS)

    This paper was written for a talk given by E. Broda in Vienna for an event organised by the chemical physical society, the Austrian biochemical society and the Austrian biophysical society in December 1972. In this paper Broda analyses the question of biopositive effects of ionizing radiation. (nowak)

  13. Trends in resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    The author reviews the history of resonance ionization spectroscopy and then comments on the delineations of RIS with reference to many related laser processes. The substance of the paper deals with the trends in RIS and especially how the needs for sensitive analytical methods have overshadowed the orginal plan to study excited species. 9 refs., 1 fig

  14. Chemical protection against ionizing radiation

    Science.gov (United States)

    Maisin, J. R.

    Some of the problems related to chemical protection against ionizing radiation are discussed with emphasis on : definition, classification, degree of protection, mechanisms of action and toxicity. Results on the biological response modifyers (BRMs) and on the combination of nontoxic (i.e. low) doses of sulphydryl radioprotectors and BRMs are presented.

  15. Rip-Stop Reinforced Thin Film Sun Shield Structure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — During a proposed Phase I and Phase II program, PSI will advance the TRL from 3 to 6 for the ripstop reinforcement of thin film membranes used for large deployable...

  16. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    The efficient dose of ionizing radiation (I.R.), expressed in sievert is a weighting of the deposited energy (absorbed dose in grays) by factors that take into account the radiation hazard and tissues radiosensitivity. it is useful in radiation protection because it allows to add exposures to ionizing radiation of different nature. for low doses, it has no probabilistic value. The determinist effects of ionizing radiation are observed from thresholds of several hundred of milli sievert. The seriousness grows with the dose. The whole-body doses exceeding 8 Sv are always lethal. The radio-induced cancers are observed only for doses exceeding 100 to 200 mSv for adults, delivered at a self important dose rate. Their seriousness does not depend on the dose. Their appear fortuity (stochastic effect) with a various individual susceptibility, genetically determined. The number of eventual radio-induced cancers coming from the exposure of a high number of persons to low dose of ionizing radiation (<100 mSv) cannot be evaluated with a linear without threshold model. these models, however usually used, do not take into account the biological reality of cell defense mechanisms, tissues or whole body defense mechanisms, these one being different against low or high doses of ionizing radiation. Against low doses, the preponderant mechanism is the elimination of potentially dangerous damaged cells. Against high doses, the repair of damaged cells is imperative to preserve the tissue functions. It can lead to DNA repair errors (radio-induced mutations) and canceration. The radio-induced congenital malformations are effects with threshold. The radio-induced carcinogenesis in utero is a stochastic effect. The radio-induced hereditary congenital malformations have never been highlighted for man. (N.C.)

  17. Ionization Thresholds of Small Carbon Clusters: Tunable VUVExperiments and Theory

    Energy Technology Data Exchange (ETDEWEB)

    Belau, Leonid; Wheeler, Steven E.; Ticknor, Brian W.; Ahmed,Musahid; Leone, Stephen R.; Allen, Wesley D.; Schaefer III, Henry F.; Duncan, Michael A.

    2007-07-31

    Small carbon clusters (Cn, n = 2-15) are produced in amolecular beam by pulsed laser vaporization and studied with vacuumultraviolet (VUV) photoionization mass spectrometry. The required VUVradiation in the 8-12 eV range is provided by the Advanced Light Source(ALS) at the Lawrence Berkeley National Laboratory. Mass spectra atvarious ionization energies reveal the qualitative relative abundances ofthe neutral carbon clusters produced. By far the most abundant species isC3. Using the tunability of the ALS, ionization threshold spectra arerecorded for the clusters up to 15 atoms in size. The ionizationthresholds are compared to those measured previously with charge-transferbracketing methods. To interpret the ionization thresholds for differentcluster sizes, new ab initio calculations are carried out on the clustersfor n = 4-10. Geometric structures are optimized at the CCSD(T) levelwith cc-pVTZ (or cc-pVDZ) basis sets, and focal point extrapolations areapplied to both neutral and cation species to determine adiabatic andvertical ionization potentials. The comparison of computed and measuredionization potentials makes it possible to investigate the isomericstructures of the neutral clusters produced in this experiment. Themeasurements are inconclusive for the n = 4-6 species because ofunquenched excited electronic states. However, the data provide evidencefor the prominence of linear structures for the n = 7, 9, 11, 13 speciesand the presence of cyclic C10.

  18. Room temperature liquid ionization chambers using tetramethylsilane

    International Nuclear Information System (INIS)

    Ionization pulse signals due to 207Bi conversion electrons were observed in ionization chambers filled with tetramethylsilane which was purified by a simple method. Pulse height spectra and its variation with the electric field were measured. (orig.)

  19. Nuclear Propulsion using Thin Foiled Fuel

    Science.gov (United States)

    Takahashi, H.

    1998-11-01

    A new way to produce plasma for nuclear propulsion is proposed. A thin foiled fuel can be used for converting fission energy to propulsion energy efficiently. The fission products coming out of the thin foil directly ionize the hydrogen molecules which are used for propulsion. Thus very small portion of fission energy deposited in the thin foil, and integrity of the thin foiled fuel can be maintained even in high nuclear power. Fuel material with large thermal fission cross-section is preferable to make thin foiled fuel and the heat deposition in the foil can be reduced. To get high power from the foiled fuel assembly, thermal neutrons which are created out from the assembly can be supplied, or the assembly itself can create the high intensity thermal neutrons by self-multiplication. A flexible design of a highly efficient nuclear propulsion system can be made. The thickness of the foil and the maintenance of the thermo-mechanical integrity can be determined from the fission cross-section and the slowing down power for fission products. The talk discusses the issues related to heat removal from the assembly.

  20. Advanced Magnetic Nanostructures

    CERN Document Server

    Sellmyer, David

    2006-01-01

    Advanced Magnetic Nanostructures is devoted to the fabrication, characterization, experimental investigation, theoretical understanding, and utilization of advanced magnetic nanostructures. Focus is on various types of 'bottom-up' and 'top-down' artificial nanostructures, as contrasted to naturally occurring magnetic nanostructures, such as iron-oxide inclusions in magnetic rocks, and to structures such as perfect thin films. Chapter 1 is an introduction into some basic concepts, such as the definitions of basic magnetic quantities. Chapters 2-4 are devoted to the theory of magnetic nanostructures, Chapter 5 deals with the characterization of the structures, and Chapters 6-10 are devoted to specific systems. Applications of advanced magnetic nanostructures are discussed in Chapters11-15 and, finally, the appendix lists and briefly discusses magnetic properties of typical starting materials. Industrial and academic researchers in magnetism and related areas such as nanotechnology, materials science, and theore...

  1. Five-photon double ionization of helium

    Science.gov (United States)

    Li, Y.; Pindzola, M. S.; Colgan, J.

    2016-03-01

    A time-dependent close-coupling method is used to calculate the five-photon double ionization of He. It is found that the generalized cross section used in the past for two-photon double ionization of He cannot be extended to five-photon double ionization of He. Therefore only five-photon double ionization probabilities that depend on specific radiation field pulses can be calculated.

  2. LARGE VOLUME IONIZATION CHAMBER USED AS LABORATORY REFERENCE FOR LOW ENERGY X—RAY MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    杨国山; 薛永库; 等

    1994-01-01

    A large volume spherical ionization chamber of 195mm diameter and 0.36mg/cm2 wall thickness made from conducting carbon-fibre epoxy composite material has been developed.The mechanical intensity of the chamber is satisfactory for a good longterm volume stability.Owing to its large volume and thin wall,the chamber is sensitive to low energy photon beams and has excellent energy-response characteristics.This ionization chamber is suitable not only for a laboratory reference but also for measurement of low energy photon beam exposure rates at protection-level.

  3. Thermoluminescence of thin films deposited by laser ablation; Termoluminiscencia de peliculas delgadas depositadas por ablacion laser

    Energy Technology Data Exchange (ETDEWEB)

    Escobar A, L.; Camps, E.; Arrieta, A.; Romero, S.; Gonzalez, P.R.; Olea M, O.; Diaz E, R. [Depto. de Fisica, ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2003-07-01

    Materials in thin film form have received great attention in the last few years mainly because of their singular properties, which may differ significantly from their bulk attributes making them attractive for a wide variety of applications. In particular, thermoluminescence (Tl) properties of thin films have been studied recently owing to their potential applications in detection for both ionizing and non ionizing radiation. The aim of the present work is to report the synthesis and characterization of C Nx, aluminum oxide and titanium oxide thin films. Thermoluminescence response of the obtained thin films was studied after subject thin films to UV radiation (254 nm) as well as to gamma radiation (Co-60). Thermoluminescence glow curves exhibited a peak centered at 150 C for CN{sub x} whereas for titanium oxide the glow curve shows a maximum peaking at 171 C. Characterization of the physical properties of the deposited materials is presented. (Author)

  4. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  5. Position-sensitive ionization detectors for ionizing beams diagnostics

    CERN Document Server

    Artemiev, A N; Mikhailov, V; Rezvov, V; Yudin, L

    2002-01-01

    Ionizing detectors for on-line non-destructive monitoring of the geometric parameters of ionizing beams have been proposed. Such a detector can be used on a beamline with a residual gas pressure of about 10 sup - sup 3 -10 sup - sup 6 Torr. It measures the product of ionization of the residual gas by the beam under investigation. An electric field moves the ions through a narrow slit into an analyzer. The analyzer field transforms the energy distribution of the ions into a two-dimensional space distribution on the outer analyzer plane. An Open Image Converter Tube (ICT) with an amplifier consisting of two Micro Channel Plates (MCP) forms an image of the real beam cross-section. This image is registered by a video camera, processed and stored on a computer. The detectors were successfully tested on beams of charged particles with wide energy and intensity ranges and on synchrotron radiation beams. Codes developed give the distribution of the beam density along its cross-section, beam profiles, the position of ...

  6. Position-sensitive ionization detectors for ionizing beams diagnostics

    International Nuclear Information System (INIS)

    Ionizing detectors for on-line non-destructive monitoring of the geometric parameters of ionizing beams have been proposed. Such a detector can be used on a beamline with a residual gas pressure of about 10-3-10-6 Torr. It measures the product of ionization of the residual gas by the beam under investigation. An electric field moves the ions through a narrow slit into an analyzer. The analyzer field transforms the energy distribution of the ions into a two-dimensional space distribution on the outer analyzer plane. An Open Image Converter Tube (ICT) with an amplifier consisting of two Micro Channel Plates (MCP) forms an image of the real beam cross-section. This image is registered by a video camera, processed and stored on a computer. The detectors were successfully tested on beams of charged particles with wide energy and intensity ranges and on synchrotron radiation beams. Codes developed give the distribution of the beam density along its cross-section, beam profiles, the position of the center of gravity and its displacement. Statistical processing increases the signal/background ratio more than 10 times, and evaluates the position of the center of gravity with an uncertainty of about 1 μm

  7. Recent advance in study on FAC

    International Nuclear Information System (INIS)

    Flow accelerated corrosion (FAC) is an important issue for aging fossil and nuclear power plants. FAC causes thinning of pipe walls which occasionally leads to a piping rupture accident. 'Research Committee on Improvement and Practical Use of Pipe-Wall-Thinning Management' of JSME revised technical knowledge regarding pipe wall thinning phenomena attached to JSME 'Code for Power Generation Facilities - Rule on Pipe Wall Thinning Management-JSME-S CA1 2005.' This paper summarizes the technical knowledge of recent advances in study on FAC. (author)

  8. TiO2 thin film photocatalyst

    Institute of Scientific and Technical Information of China (English)

    YU Jiaguo

    2004-01-01

    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  9. Energy distributions for ionization in ion-atom collisions

    CERN Document Server

    Amaya-Tapia, A

    2016-01-01

    In this paper we discuss how through the process of applying the Fourier transform to solutions of the Schr\\"odinger equation in the Close Coupling approach, good results for the ionization differential cross section in energy for electrons ejected in ion-atom collisions are obtained. The differential distributions are time dependent and through their time average, the comparison with experimental and theoretical data reported in the literature can be made. The procedure is illustrated with reasonable success in two systems, $p+H$ and $p+He$, and is expected to be extended without inherent difficulties to more complex systems. This allows advancing in the understanding of the calculation of ionization processes in ion-atom collisions.

  10. Laser ionization of molecular clusters

    International Nuclear Information System (INIS)

    Multiphoton ionization coupled with mass spectrometry was used to investigate molecular cluster distributions. Three examples will be discussed in this presentation. First, in studies of neat nitric oxide clusters, (NO)m, an interesting odd-even intensity alternation was observed and will be discussed in terms of electron-pairing considerations. In a separate study, the binary clusters comprising nitric oxide and methane preferentially form a stoichiometric cluster made up of repeating units of (NO)2CH4. These presumably represent a particularly strongly bound open-quotes van der Waalsclose quotes subunit. Finally, in similar studies of neat carbon disulfide clusters, (CS2)m, additional photon absorption after the two-photon ionization step stimulates a series of intracluster ion-molecular reactions leading to formation of Sm+ and (CS)m+ polymers, as well as intermediate species such as Sm+ (CS2). This molecular cluster analogue of open-quotes laser snowclose quotes will be described in detail

  11. Ionization potentials some variations, implications and applications

    CERN Document Server

    Ahrens, L H

    1983-01-01

    Ionization Potentials: Some Variations, Implications and Applications covers several aspects of ionization potential that is a highly significant parameter in controlling the properties of electric discharge. Comprised of 17 chapters, the book covers topic relevant to ionization potentials, such as properties, concepts, and applications, in order to understand and fully comprehend all aspects of ionization potential. The opening chapter is a review of ionization potentials and a discussion of trends and features. The succeeding chapters then tackle complex topics such as the s and p electrons;

  12. Very small ionization pressure gauge

    International Nuclear Information System (INIS)

    A very small ionization pressure gauge has been developed to operate in the pressure range 10-6 Torr to 100μ. A metal construction and external cooling fins result in a very rugged device with exceptionally small outgassing properties. The gauge also incorporates a replaceable filament-grid assembly on a single plug which allows the simple replacement of both the filament and the grid when needed

  13. Laser resonance ionization mass spectrometer

    International Nuclear Information System (INIS)

    The setup is elaborated for the trace detection of transuranium elements by the three-step laser resonance ionization combined with the time-of-flight mass spectrometry. The setup efficiency for detection of plutonium was measured to be about 0.5 centre dot 10-8 ion/atom, and its selectivity relative to atoms of another elements has the order of 1013 atom/atom

  14. Risks Associated with Ionizing Radiations

    International Nuclear Information System (INIS)

    Medical use of ionizing radiations implies certain risks which are widely balanced by their diagnostic and therapeutic benefits. Nevertheless, knowledge about these risks and how to diagnose and prevent them minimizes their disadvantages and optimizes the quality and safety of the method. This article describes the aspects related to skin dose (nonstochastic effects), the importance of dose limit, the physiopathology of biological damage and, finally, the prevention measures.

  15. The dosimetry of ionizing radiation

    CERN Document Server

    1990-01-01

    A continuation of the treatise The Dosimetry of Ionizing Radiation, Volume III builds upon the foundations of Volumes I and II and the tradition of the preceeding treatise Radiation Dosimetry. Volume III contains three comprehensive chapters on the applications of radiation dosimetry in particular research and medical settings, a chapter on unique and useful detectors, and two chapters on Monte Carlo techniques and their applications.

  16. Walls shielding against ionizing radiation

    International Nuclear Information System (INIS)

    These specifications are to help the users of lead bricks as under DIN 25407, leaf 1, with the construction of walls shielding against ionizing radiation by examples for the uses of the different types of lead bricks and by recommendations for the construction of shielding walls and for the determination of the wall thickness necessary for shielding against γ-radiation as a function of energy. (orig./AK)

  17. Nuclear worker and ionizing radiation

    International Nuclear Information System (INIS)

    Research on medical X-ray exposure sheds light on the health effects expected for workers exposed to ionizing radiation. Factual information confirming this relationship and also demonstrating the need for reviewing permissible exposure levels for workers is given. Suggestions for more sophisticated health monitoring of workers exposed to hazardous technologies are made, and the question of occupational hazards which threaten the worker's family is raised

  18. Ionizing radiation perception by insects

    International Nuclear Information System (INIS)

    The proof of the existence of a perception for ionizing radiation by insects was aimed at, as well as the determination of its processing mechanism. It was tried also to check if such perception induces the insects to keep away from the radiation source, proving therefore a protection against the harms caused by ionizing radiation, or else the stimulus for such behaviour is similar to that caused by light radiations. 60Co and 241Am were used as gamma radiation sources, the 60Co source of 0.435mCi and the 241Am of 99.68mCi activity. Adult insects were used with the following treatments : exposure to 60Co and 241Am radiation and non-exposure (control). A total of approximately 50 insects per replication was released in the central region of an opaque white wooden barrier divided into 3 sections with the same area - 60.0 cm diameter and 7.5 cm height - covered with a nylon screen. 5 replications per treatment were made and the distribution of the insects was evaluated by photographs taken at 15, 30, 45, and 60 minutes after release. Sitophilus oryzae (l., 1763) and Ephestia cautella (Walker, 1864) showed some response to 241Am gamma radiation, i.e. negative tactism. It was concluded that ionizing radiations can be detected by insects through direct visual stimulus or by visual stimulus reslting from interaction of radiation-Cerenkov radiation - with some other occular component with a refraction index greater than water. Also, the activity of the radioactive source with regard to perception for ionizing radiation, is of relevance in comparison with the energy of the radiation emitted by same, or in other words, what really matters is the radiation dose absorbed. (Author)

  19. Ionization of H Rydberg atoms

    International Nuclear Information System (INIS)

    Concepts from the theory of transient chaos are applied to study the classical ionization process of one dimensional model of kicked hydrogen Rydberg atoms. The phase-space dynamics is represented by a mapping T which is proved to be hyperbolic. The fraction of atoms not ionized after time t, PB(t), decays asymptotically according to PB(t)∼t-α with α ∼ 1.65. The observed algebraic decay, which seems to contradict the hyperbolicity of T, is explained by (i) the symbolic dynamics of T consists of a countably infinite number of symbols and (ii) the invariant manifold of phase-space points which never ionize is an anomalously scaling fractal. Therefore, the one-dimensional kicked hydrogen atom provides a counterexample to the hypothesis that algebraic decay marks regular dynamics, whereas hyperbolic systems decay exponentially. The algebraic decay is reproduced by an analytically solvable diffusion model which predicts α = 3/2. Replacing zero-width δ-kicks by smooth finite-width pulses, the mapping T is no longer completely hyperbolic, and a subset of phase-space is regular. For this case we observe that PB(t) shows a transition between two power-law decays with α ∼ 1.65 for short times and α ∼ 2.1 for long times where the effect of the regular domain is felt. (author)

  20. Theory of dissociative tunneling ionization

    Science.gov (United States)

    Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

    2016-05-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees of freedom. In the regime where the BO approximation is applicable, imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally, the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fields, where the BO approximation does not apply, the weak-field asymptotic theory describes the spectrum accurately.

  1. Similarity of ionized gas nebulae around unobscured and obscured quasars

    Science.gov (United States)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.

    2014-08-01

    Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper, we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O III] λ5007 Å emission line. We find that ionized gas nebulae extend out to ˜13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O III] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore, in samples of obscured and unobscured quasars carefully matched in [O III] luminosity, we find support for the standard geometry-based unification model of active galactic nuclei, in that the intrinsic properties of the quasars, of their hosts and of their ionized gas appear to be very similar. Given the apparent ubiquity of extended ionized regions, we are forced to conclude that either the quasar is at least partially illuminating pre-existing gas or that both samples of quasars are seen during advanced stages of quasar feedback. In the latter case, we may be biased by our [O III]-based selection against quasars in the early `blow-out' phase, for example due to dust obscuration.

  2. Abstracts from the fourth annual meeting of the council on ionizing radiation measurements and standards (CIRMS)

    International Nuclear Information System (INIS)

    The Council on Ionizing Radiation Measurements and Standards held its fourth annual meeting at the National Institute of Standards and Technology, Gaithersburg, Maryland on November 28-30, 1995. The organization represents thousands of users of ionizing radiation and radioactive sources engaged in industrial radiation processing and sterilization, medical radiation diagnostics and therapy, nuclear power, and worker radiation protection programs. CIRMS provides a forum for discussing ionizing radiation issues; identifying, defining and prioritizing needed work; disseminating information on standards; and organizing workshops and meetings to advance ionizing radiation technology. Over 100 participants attended the meeting, which highlighted advanced techniques in radiation dosimetry and radioactivity measurements for the different ionizing radiation communities. Representatives attended from 28 corporations, 10 federal agencies, 8 national laboratories, 12 universities, and 1 state. Advanced techniques and future measurement needs were discussed in four sessions: (I) Medical Dosimetry, Radiology and Nuclear Medicine, (II) Occupational and Radiation Protection Dosimetry, (III) Measurement Techniques for Public and Environmental Radiation Protection, and (IV) Measurement Techniques for Radiation Effects on Materials. An additional session (Session V) was added to this annual meeting on the implementation of ISO 9000 for those CIRMS members involved in instrument and product manufacturing, and those providing radiation measurement services. Abstracts are also included from the poster session (Session VI) held on the final day of the meeting. The 4th Annual Meeting was organized by the Chairman of the Science and Technology Committee, Mr. Joseph C. McDonald of the Battelle Pacific Northwest Laboratory

  3. Semiconductor behavior of hydrided Dy thin films as a function of increasing hydrogen pressure

    International Nuclear Information System (INIS)

    Polycrystalline Dy thin films, coated with a very thin Pd layer, have been deposited on glass substrates by electron beam evaporation and subsequently hydrided. For hydrogen partial pressures larger than 0.7 kPa, a semiconductor character is displayed in the optical properties of the DyH2+x thin films. A parametric model is applied to follow the evolution with hydrogen pressure of various parameters characterizing the absorption by the semiconductor DyH2+x thin films. The contribution of the free electrons to the absorption of light is also considered within a Drude model incorporating the presence of the hydrogen atoms as ionized impurity scattering centers

  4. Effect of p-Layer and i-Layer Properties on the Electrical Behaviour of Advanced a-Si:H/a-SiGe:H Thin Film Solar Cell from Numerical Modeling Prospect

    OpenAIRE

    Peyman Jelodarian; Abdolnabi Kosarian

    2012-01-01

    The effect of p-layer and i-layer characteristics such as thickness and doping concentration on the electrical behaviors of the a-Si:H/a-SiGe:H thin film heterostructure solar cells such as electric field, photogeneration rate, and recombination rate through the cell is investigated. Introducing Ge atoms to the Si lattice in Si-based solar cells is an effective approach in improving their characteristics. In particular, current density of the cell can be enhanced without deteriorating its ope...

  5. Recent Methods for the Automatic Evaluation of Thin-Layer and Paper Chromatograms of Labelled Substances

    International Nuclear Information System (INIS)

    The development and results obtained with a new instrument for the automatic scanning of thin-layer and paper chromatograms of labelled substances is described. Using a novel type of gas-flow detector, it is possible to measure all beta-emitters, including 3H, without contact with the probe. Essentially the apparatus consists of a detector and a transport mechanism passing the chromatogram below the detector diaphragm. In view of the small half-value layer of beta-particles in air (approx. 0.3 mm) a strong dependence on distance between detector and chromatogram would be expected. However, there is practically no dependence between 0.5 and 2 mm distance. The explanation presented is that because of the special counter parameters the electrical field extends through the opening of the diaphragm into the space between counter and chromatogram, thereby pulling negative charge carriers produced by ionizing radiation even outside the counter volume into the region of gas amplification around the anode wire. Therefore, the instrument allows fast, direct and non-destructive measurement of thin-layer plates even for 3H, as opposed to the common practice of scraping off small areas of the thin layer and measuring the radioactivity in a liquid scintillation counter. The transport mechanism in its most recent version allows two-dimensional automatic scanning, with continuous or stepwise advance, and correspondingly analogous or digital registration. A ''dot'' recording allows simple visualization of the chromatogram, similar to an autoradiograph, however, in a much shorter time. Small available diaphragm openings down to 0.2 x 2 mm make the instrument useful also for histological preparations and small animal scanning. The instrument is also used for evaluating doubly-labelled chromatograms, for instance separate measurement of 3H and 14C activity in one chromatogram. (author)

  6. Femtosecond Laser Ionization of Organic Amines with Very Low Ionization Potential.

    Science.gov (United States)

    Yatsuhashi, Tomoyuki; Obayashi, Takashi; Tanaka, Michinori; Murakami, Masanao; Nakashima, Nobuaki

    2006-03-01

    The interaction between high intensity femtosecond laser and molecules is one of the most attractive areas in laser chemistry and ionization is the most fundamental subject. Theoretical consideration successfully reproduced the ionization behavior of rare gases. However, the understanding of ionization mechanisms of large molecules is difficult more than those of rare gases due to their complexity. Generally speaking, molecules are harder to ionize than rare gases even if they have the same ionization potential. The suppressed ionization phenomena are one of the important features of molecular ionization. Hankin et al. examined 23 organic molecules with ionization potentials between 8.25 and 11.52 eV. We have examined ionization and/ or fragmentation of many organic molecules, including aromatic compounds, halogenated compounds, methane derivatives etc. at various wavelengths below 10^16 Wcm-2. In order to investigate the nature of molecular ionization, it is interesting to examine a variety of molecule in a wide range of ionization potential. In this study, we examined several organic amines because we can explore the uninvestigated ionization potential range down to 5.95 eV. In addition to the significant suppression of the ionization rates, stepwise ionization behavior, which was not observed in rare gases, was observed.

  7. Effect of p-Layer and i-Layer Properties on the Electrical Behaviour of Advanced a-Si:H/a-SiGe:H Thin Film Solar Cell from Numerical Modeling Prospect

    Directory of Open Access Journals (Sweden)

    Peyman Jelodarian

    2012-01-01

    Full Text Available The effect of p-layer and i-layer characteristics such as thickness and doping concentration on the electrical behaviors of the a-Si:H/a-SiGe:H thin film heterostructure solar cells such as electric field, photogeneration rate, and recombination rate through the cell is investigated. Introducing Ge atoms to the Si lattice in Si-based solar cells is an effective approach in improving their characteristics. In particular, current density of the cell can be enhanced without deteriorating its open-circuit voltage. Optimization shows that for an appropriate Ge concentration, the efficiency of a-Si:H/a-SiGe solar cell is improved by about 6% compared with the traditional a-Si:H solar cell. This work presents a novel numerical evaluation and optimization of amorphous silicon double-junction (a-Si:H/a-SiGe:H thin film solar cells and focuses on optimization of a-SiGe:H midgap single-junction solar cell based on the optimization of the doping concentration of the p-layer, thicknesses of the p-layer and i-layer, and Ge content in the film. Maximum efficiency of 23.5%, with short-circuit current density of 267 A/m2 and open-circuit voltage of 1.13 V for double-junction solar cell has been achieved.

  8. Liquid-argon cylindrical pulsed ionization chamber

    International Nuclear Information System (INIS)

    A liquid-argon cylindrical ionization chamber with a working volume of 200 cm2 is described. The chamber anode is made of stainless steel in the form of a hollow cylinder 30 mm in diameter and 140 mm in length. A beryllium bronze wire in diameter of 0.1 mm and at a spacing of 1 mm is used for winding the chamber screen grid. The chamber cathode is a brass thin-walled cylinder having an internal diameter of 56 mm and a height of 156 mm. The cathode-grid gap is 10 mm, the cathode-case gap is 2 mm. A 0.5 l cooling bath filled with liquid nitrogen is used to refrigirate the chamber. The chamber is evacuated to about 10-5 mm Hg. The total concentration of electronegative impurities in argon does not exceed 6x10-9. Dependences of the chamber counting and amplitude responses, on the cathode voltage under irradiation with γ-quanta at energies of 0.898 MeV and 1.836 MeV are given. The value of the energy resolution was evaluated by differentiating the high-energy edge of the Compton spectrum. The total width at a peak half-height constitutes 5% for an electron energy of 1.612 MeV. To achieve better resolution of the chamber it is necessary to reduce preamplifier noises by three times, to increase the working gap of the chamber and decrease the grid-anode gap

  9. Advanced materials-2003

    International Nuclear Information System (INIS)

    The 8th International Symposium on Advanced Materials (ISAM) was held from 8-11 September, 2003. The proceeding of ISAM includes 87 papers which have been divided in to ten different sections. These include production and processing, coating and thin films, characterization, superconductors and semiconductors mechanical modeling, mechanical testing and life prediction composites, corrosion and oxidation, single crystals and related papers. Ten eminent researchers and scholars of international fame presented their keynote/invited lectures of 40 minutes each. This symposium provided an ideal opportunity for exchange of information amongst scientists, engineers, and researchers from all over Pakistan and 30 other countries of the world. (A.B.)

  10. Advanced Ceramics

    International Nuclear Information System (INIS)

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.)

  11. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  12. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  13. Energy expenditure for water molecule ionization by electron impact in weakly ionized plasma

    International Nuclear Information System (INIS)

    The energy balance of the water molecule ionization by a monoenergetic electron beam with the energy of primary electrons in the interval of 15-1000 eV has been calculated. The dependences of the ionization cost on the water ionization degree within the interval from 0 to 0.1 are obtained. The ionization cost is shown to increase with the ionization degree. In particular, for a primary electron energy of 1000 eV, it increases from 25.26 to 52.45 eV in the examined ionization degree interval

  14. Quasi free mechanism in single photon double ionization of helium

    International Nuclear Information System (INIS)

    Double ionization of Helium by a single photon is widely believed to proceed through two mechanisms: knock-off (TS1) or shake-off, with the last one dominating at high photon energies. A new mechanism, termed ''Quasi Free Mechanism'' (QFM) was predicted 35 years ago by Amusia and coworkers, but escaped experimental observation till today. Here we provide the first proof of this mechanism using 800 eV photons from the Advanced Light Source. Fragments (electrons and ions) were measured in coincidence using momentum spectroscopy (COLTRIMS). He(2+) ions with zero momentum were found - the fingerprint for the QFM.

  15. Multiphoton ionization of uranium hexafluoride

    International Nuclear Information System (INIS)

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy (TOFMS) and photoelectron spectroscopy (PES) studies of UF6 are reported using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF+x fragment ions, even at the lowest laser power densities at which signal could be detected. In general, the doubly charged uranium ion (U2+) intensity is much greater than that of the singly charged uranium ion (U+). For the case of the tunable dye laser experiments, the Un+ (n=1--4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The MPI-PES studies reveal only very slow electrons (≤0.5 eV) for all wavelengths investigated. The dominance of the U2+ ion, the absence or very small intensities of UF+x (x=1--3) fragments, the unstructured wavelength dependence, and the preponderance of slow electrons all indicate that mechanisms may exist other than ionization of bare U atoms following the stepwise photodissociation of F atoms from the parent molecule. The data also argue against stepwise photodissociation of UF+x (x=5,6) ions. Neither of the traditional MPI mechanisms (''neutral ladder'' or the ''ionic ladder'') are believed to adequately describe the ionization phenomena observed. We propose that the multiphoton excitation of UF6 under these experimental conditions results in a highly excited molecule, superexcited UF6**

  16. Mirage: a new proton facility for the study of direct ionization in sub-100 nm technologies

    OpenAIRE

    Duzellier, S.; Hubert, G.; Rey, R.; F. Bezerra

    2014-01-01

    A new proton beam line has been developed at ONERA for investigating radiation effects in electronics. Standard beams are used for studying cumulated effects in optoelectronics and photonics, low current configuration has been developed for studying direct ionization effects in advanced digital technologies.

  17. Optical Detection of Tunneling Ionization

    Science.gov (United States)

    Verhoef, Aart J.; Mitrofanov, Alexander V.; Serebryannikov, Evgenii E.; Kartashov, Daniil V.; Zheltikov, Aleksei M.; Baltuška, Andrius

    2010-04-01

    We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

  18. Optical Detection of Tunneling Ionization

    International Nuclear Information System (INIS)

    We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

  19. Ionization chambers for LET determination

    DEFF Research Database (Denmark)

    Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki;

    2010-01-01

    Modern radiotherapy facilities for cancer treatment such as the Heavy Ion Therapy Centre (HIT) in Heidelberg (Germany) enable sub millimetre precision in dose deposition. For the measurement of such dose distributions and  characterization of the particle beams, detectors with high spatial...... of columnar recombination was designed to model the detector efficiency of an ionization chamber. Here, we have shown that despite the approximations and simplification made, the theory is correct for the LETs typically found in clinical radiotherapy employing particles from protons to carbon ions...

  20. XUV ionization of aligned molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kelkensberg, F.; Siu, W.; Gademann, G. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Rouzee, A.; Vrakking, M. J. J. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Max-Born-Institut, Max-Born Strasse 2A, D-12489 Berlin (Germany); Johnsson, P. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Department of Physics, Lund University, Post Office Box 118, SE-221 00 Lund (Sweden); Lucchini, M. [Department of Physics, Politecnico di Milano, Istituto di Fotonica e Nanotecnologie CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Lucchese, R. R. [Department of Chemistry, Texas A and M University, College Station, Texas 77843-3255 (United States)

    2011-11-15

    New extreme-ultraviolet (XUV) light sources such as high-order-harmonic generation (HHG) and free-electron lasers (FELs), combined with laser-induced alignment techniques, enable novel methods for making molecular movies based on measuring molecular frame photoelectron angular distributions. Experiments are presented where CO{sub 2} molecules were impulsively aligned using a near-infrared laser and ionized using femtosecond XUV pulses obtained by HHG. Measured electron angular distributions reveal contributions from four orbitals and the onset of the influence of the molecular structure.

  1. Influence of multiple ionization in laser filamentation

    International Nuclear Information System (INIS)

    Laser filaments in gases result from the nonlinear balance between optical Kerr self-focusing and plasma generation in the single ionization limit, i.e., the pulse intensity is supposed to remain moderate enough (∼1014 W cm−2) to apply photo-ionization theories valid for an averaged ion charge less than unity. However, no theory has attempted so far to consider how an ionization model allowing a priori multiple-charged states could impact the standard filamentation scenario. Here, we discuss a multiple photo-ionization scheme that relies on probabilities assuming successive single-electron ionizations. We numerically show that a multiple ionization scheme can increase the clamping intensity, the peak electron density and supercontinuum generation in gases with high binding energy, e.g., helium. (paper)

  2. Multiphoton ionization with femtosecond laser pulses

    International Nuclear Information System (INIS)

    There are a number of reasons to use subpicosecond pulses in multiphoton ionization experiments. Pulses with shorter risetimes make it possible to study processes with higher rates before one runs into the problem of depletion of target atoms. Furthermore, the momentum of the electron does not change between the point of ionization and the detector if the pulse expires before the electron has time to sample the spatial inhomogeneity of the light intensity. This makes it possible to identify the intensity at which an electron was formed from the energy with which it reaches the detector. Yet another advantage is the fact that the primary ionization products are subject to the ionizing radiation for only a short amount of time, thus reducing the probability of sequential ionization as compared to direct processes. In this paper the experimental results on the multiphoton ionization of xenon with pulses of 100 fs, that were obtained during the preceding year at ENSTA, Palaiseau, will be presented

  3. New thin materials for electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzberg, Adam

    2012-02-01

    The work described in this report is from an Early Career LDRD to develop and investigate novel thin film organic conductors with drastically improved electronic properties over the current state of the art. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory a Langmuir-Blodgett trough (LB) was built from scavenged parts and added to a scanning Raman microscope at LBNL. First order thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have helped position Sandia for advances in this area of MOF film creation. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory, a Langmuir-Blodgett trough (LB) was built and added to a scanning Raman microscope at LBNL. Thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy, and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have positioned Sandia for advance in this area of MOF film creation. The interactions with LBNL also led to award of two user projects at the Molecular Foundry at LBNL led by current Sandia staff and the appointment of a current Sandia staff to the Molecular Foundry User Executive Committee.

  4. ATOMS INTERACTING WITH ELECTROMAGNETIC FIELDS, MULTIPHOTON IONIZATION

    OpenAIRE

    Mainfray, G

    1982-01-01

    The non linear interaction between an intense laser radiation and atoms leads to ionization through the absorption of N photons from the laser radiation via laser-induced virtual states. The multiphoton ionization rate varies as a function of the laser intensity I as IN. We discuss the two most important effects which govern multiphoton ionization processes : resonance effects and laser-coherence effects. In a moderate laser intensity range (107 - 109 W cm-2) corresponding to the two, three o...

  5. Spatially discontinuous ionization phenomenon in inhomogeneous soil

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By using X-ray film imaging technology,a phenomenon of discontinuous ionization was observed in the inhomogeneous soil around the grounding electrode on which a surge voltage was applied.A simplified two-phase solid-gas model was built to study the electric field distribution in the soil to explain the discontinuous ionization phenomenon.Analysis showed the differences of the dielectric properties,the shapes and sizes of soil particles can cause discontinuous ionization in the soil.

  6. Quantum electrodynamic perspective on multiphoton ionization

    International Nuclear Information System (INIS)

    A fully quantum nonperturbative method is developed to describe multiphoton ionization in intense fields. It is shown that, treating the radiation field with quantum electrodynamic (QED) theory enables the authors to obtain the above-threshold ionization energy distribution spectrum in analytical form firstly. Moreover, in addition to the well-known semiclassical theory, the framework presented here, derived from a QED perspective, provides a new picture of the multiphoton ionization

  7. Theoretical investigations of a double ionization chamber for on-line monitoring of tritium production in fusion blankets

    International Nuclear Information System (INIS)

    This paper reports that a double ionization chamber employing a thin coating of enriched 6LiF radiating material offers an effective means of identifying a 6Li(n, α)t reaction. The concept is based on the detection of ionization caused by alpha particles and tritons. The charged particles emitted in opposite directions can be detected by a double parallel plate ionization chamber configuration. This method can therefore be employed to directly measure tritium breeding rates inside the fusion blankets. Complete details of the parameters that govern the response of such a detector system are described. A Monte Carlo scheme is developed to determine the direction and energy lost by the particles in traversing various media, and the detector response is calculated from the energy deposited in the ionization region of each chamber. The calculations are performed for the entire energy range of neutrons available in the fusion blankets

  8. Composite electron propagator methods for calculating ionization energies

    Science.gov (United States)

    Díaz-Tinoco, Manuel; Dolgounitcheva, O.; Zakrzewski, V. G.; Ortiz, J. V.

    2016-06-01

    Accurate ionization energies of molecules may be determined efficiently with composite electron-propagator (CEP) techniques. These methods estimate the results of a calculation with an advanced correlation method and a large basis set by performing a series of more tractable calculations in which large basis sets are used with simpler approximations and small basis sets are paired with more demanding correlation techniques. The performance of several CEP methods, in which diagonal, second-order electron propagator results with large basis sets are combined with higher-order results obtained with smaller basis sets, has been tested for the ionization energies of closed-shell molecules from the G2 set. Useful compromises of accuracy and computational efficiency employ complete-basis-set extrapolation for second-order results and small basis sets in third-order, partial third-order, renormalized partial-third order, or outer valence Green's function calculations. Analysis of results for vertical as well as adiabatic ionization energies leads to specific recommendations on the best use of regular and composite methods. Results for 22 organic molecules of interest in the design of photovoltaic devices, benzo[a]pyrene, Mg-octaethylporphyrin, and C60 illustrate the capabilities of CEP methods for calculations on large molecules.

  9. Composite electron propagator methods for calculating ionization energies.

    Science.gov (United States)

    Díaz-Tinoco, Manuel; Dolgounitcheva, O; Zakrzewski, V G; Ortiz, J V

    2016-06-14

    Accurate ionization energies of molecules may be determined efficiently with composite electron-propagator (CEP) techniques. These methods estimate the results of a calculation with an advanced correlation method and a large basis set by performing a series of more tractable calculations in which large basis sets are used with simpler approximations and small basis sets are paired with more demanding correlation techniques. The performance of several CEP methods, in which diagonal, second-order electron propagator results with large basis sets are combined with higher-order results obtained with smaller basis sets, has been tested for the ionization energies of closed-shell molecules from the G2 set. Useful compromises of accuracy and computational efficiency employ complete-basis-set extrapolation for second-order results and small basis sets in third-order, partial third-order, renormalized partial-third order, or outer valence Green's function calculations. Analysis of results for vertical as well as adiabatic ionization energies leads to specific recommendations on the best use of regular and composite methods. Results for 22 organic molecules of interest in the design of photovoltaic devices, benzo[a]pyrene, Mg-octaethylporphyrin, and C60 illustrate the capabilities of CEP methods for calculations on large molecules. PMID:27305999

  10. Ionizing radiation and orthopaedic prostheses

    International Nuclear Information System (INIS)

    Ultra high molecular weight polyethylene (UHMWPE) materials have been used successfully as one half of the bearing couple (against metallic alloys or ceramics) in total hip and total knee joint replacements for four decades. This review describes the impact of ionizing radiation (used for sterilization and for microstructural modification via crosslinking) on the performance of UHMWPE total joint replacement components. Gamma radiation sterilization in air leads to oxidative degradation of UHMWPE joint components that occurs during shelf-aging and also during in vivo use. Efforts to mitigate oxidative degradation of UHMWPE joint components include gamma radiation sterilization in inert barrier-packaging and processing treatments to reduce free radicals. Ionizing radiation (both gamma and electron-beam) has recently been used to form highly crosslinked UHMWPEs that have better adhesive and abrasive wear resistance than non-crosslinked UHMWPE, thereby potentially improving the long-term performance of total joint replacements. Along with increased wear resistance, however, there are deleterious changes to ductility and fracture resistance of UHMWPE, and an increased risk of fracture of these components remains a clinical concern

  11. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    It has been emphasised the importance of DNA as the main target for ionizing radiation, that can induce damage by its direct action on this molecule or by an indirect effect mediated by free-radicals generated by water radiolysis. Biological effects of ionizing radiation are influenced not only by the dose but also by the dose-rate and the radiation quality. Radiation induced damage, mainly DNA single and double strand breaks, is detected by molecular sensors which in turn trigger signalling cascades leading to cell cycle arrest to allow DNA repair or programmed cell death (apoptosis). Those effects related with cell death, named deterministic, exhibits a dose-threshold below which they are not observed. Acute radiation syndrome and radiological burns are examples of this kind of effects. Other radiation induced effects, called stochastic, are the consequence of cell transformation and do not exhibit a dose-threshold. This is the case of cancer induction and hereditary effects. The aim of this presentation is briefly describe the main aspects of deterministic and stochastic effects from the point of view of radiobiology and radio pathology. (author)

  12. Ionizing radiation and orthopaedic prostheses

    Science.gov (United States)

    Rimnac, Clare M.; Kurtz, Steven M.

    2005-07-01

    Ultra high molecular weight polyethylene (UHMWPE) materials have been used successfully as one half of the bearing couple (against metallic alloys or ceramics) in total hip and total knee joint replacements for four decades. This review describes the impact of ionizing radiation (used for sterilization and for microstructural modification via crosslinking) on the performance of UHMWPE total joint replacement components. Gamma radiation sterilization in air leads to oxidative degradation of UHMWPE joint components that occurs during shelf-aging and also during in vivo use. Efforts to mitigate oxidative degradation of UHMWPE joint components include gamma radiation sterilization in inert barrier-packaging and processing treatments to reduce free radicals. Ionizing radiation (both gamma and electron-beam) has recently been used to form highly crosslinked UHMWPEs that have better adhesive and abrasive wear resistance than non-crosslinked UHMWPE, thereby potentially improving the long-term performance of total joint replacements. Along with increased wear resistance, however, there are deleterious changes to ductility and fracture resistance of UHMWPE, and an increased risk of fracture of these components remains a clinical concern.

  13. Chemical protection against ionizing radiation

    International Nuclear Information System (INIS)

    Over 40 years have passed since the research of the Manhattan Project suggested the possibility of chemical protection against ionizing radiation. During that time, much has been learned about the nature of radiation-induced injury and the factors governing the expression of that injury. Thousands of compounds have been tested for radioprotective efficacy, and numerous theories have been proposed to account for these actions. The literature on chemical radioprotection is large. In this article, the authors consider several of the mechanisms by which chemicals may protect against radiation injury. They have chosen to accent this view of radioprotector research as opposed to that research geared toward developing specific molecules as protective agents because they feel that such an approach is more beneficial in stimulating research of general applicability. This paper describes the matrix of biological factors upon which an exogenous radioprotector is superimposed, and examines evidence for and against various mechanisms by which these agents may protect biological systems against ionizing radiation. It concludes with a brief outlook for research in chemical radioprotection

  14. Muon Ionization Cooling Experiment (MICE)

    CERN Document Server

    Zisman, M S

    2004-01-01

    There is presently considerable activity worldwide on developing the technical capability for a “neutrino factory” based on a muon storage ring and, a muon collider. Muons are obtained from the decay of pions produced when an intense proton beam hits a high-Z target, so the initial muon beam has a large 6-dimensional phase space. To increase the muons’ phase-space density, we use ionization cooling, which is based on energy loss in an absorber, followed by re-acceleration with high-gradient, normal-conducting RF cavities. The absorber of choice is liquid hydrogen to minimize multiple scattering. A superimposed solenoidal focusing channel contains the muons. Although the physics is straightforward, the technology and its implementation are not. The international MICE collaboration will demonstrate ionization cooling of a muon beam in a short section of a typical cooling channel. The experiment is approved for operation at Rutherford Appleton Lab. We will measure the cooling effect...

  15. Development of dielectric-barrier-discharge ionization.

    Science.gov (United States)

    Guo, Cheng'an; Tang, Fei; Chen, Jin; Wang, Xiaohao; Zhang, Sichun; Zhang, Xinrong

    2015-03-01

    Dielectric-barrier-discharge ionization is an ambient-ionization technique. Since its first description in 2007, it has attracted much attention in such fields as biological analysis, food safety, mass-spectrometry imaging, forensic identification, and reaction monitoring for its advantages, e.g., low energy consumption, solvent-free method, and easy miniaturization. In this review a brief introduction to dielectric barrier discharge is provided, and then a detailed introduction to the dielectric-barrier-discharge-ionization technique is given, including instrumentation, applications, and mechanistic studies. Based on the summary of reported work, possible future uses of this type of ionization source are discussed at the end. PMID:25510973

  16. Tunneling Ionization Time Resolved by Backpropagation

    Science.gov (United States)

    Ni, Hongcheng; Saalmann, Ulf; Rost, Jan-Michael

    2016-07-01

    We determine the ionization time in tunneling ionization by an elliptically polarized light pulse relative to its maximum. This is achieved by a full quantum propagation of the electron wave function forward in time, followed by a classical backpropagation to identify tunneling parameters, in particular, the fraction of electrons that has tunneled out. We find that the ionization time is close to zero for single active electrons in helium and in hydrogen if the fraction of tunneled electrons is large. We expect our analysis to be essential to quantify ionization times for correlated electron motion.

  17. K-shell ionization by antiprotons

    International Nuclear Information System (INIS)

    We present first calculations for the impact parameter dependence of K-shell ionization rates in anti pCu and in anti pAg collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the anti-binding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross-sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross-sections for protons. (orig.)

  18. Regulatory control of ionizing radiations in Ecuador

    International Nuclear Information System (INIS)

    This document deals with legal aspects for controlling ionizing radiations, radiological safety regulations and objectives, scopes and features of the national radioprotection planning in Ecuador. (The author)

  19. Ionization probes of molecular structure and chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.M. [State Univ. of New York, Stony Brook (United States)

    1993-12-01

    Various photoionization processes provide very sensitive probes for the detection and understanding of the spectra of molecules relevant to combustion processes. The detection of ionization can be selective by using resonant multiphoton ionization or by exploiting the fact that different molecules have different sets of ionization potentials. Therefore, the structure and dynamics of individual molecules can be studied even in a mixed sample. The authors are continuing to develop methods for the selective spectroscopic detection of molecules by ionization, and to use these methods for the study of some molecules of combustion interest.

  20. Non-sequential double ionization of molecules

    CERN Document Server

    Prauzner-Bechcicki, J S; Eckhardt, B; Zakrzewski, J; Prauzner-Bechcicki, Jakub S.; Sacha, Krzysztof; Eckhardt, Bruno; Zakrzewski, Jakub

    2004-01-01

    Double ionization of diatomic molecules by short linearly polarized laser pulses is analyzed. We consider the final stage of the ionization process, that is the decay of a highly excited two electron molecule, which is formed after re-scattering. The saddles of the effective adiabatic potential energy close to which simultaneous escape of electrons takes place are identified. Numerical simulations of the ionization of molecules show that the process can be dominated by either sequential or non-sequential events. In order to increase the ratio of non-sequential to sequential ionizations very short laser pulses should be applied.

  1. Influence of renormalization shielding on the electron-impact ionization process in dense partially ionized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Song, Mi-Young; Yoon, Jung-Sik [Plasma Technology Research Center, National Fusion Research Institute, 814-2 Osikdo-Dong, Gunsan-City, Jeollabuk-Do 573-540 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States); Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

    2015-04-15

    The renormalization shielding effects on the electron-impact ionization of hydrogen atom are investigated in dense partially ionized plasmas. The effective projectile-target interaction Hamiltonian and the semiclassical trajectory method are employed to obtain the transition amplitude as well as the ionization probability as functions of the impact parameter, the collision energy, and the renormalization parameter. It is found that the renormalization shielding effect suppresses the transition amplitude for the electron-impact ionization process in dense partially ionized plasmas. It is also found that the renormalization effect suppresses the differential ionization cross section in the peak impact parameter region. In addition, it is found that the influence of renormalization shielding on the ionization cross section decreases with an increase of the relative collision energy. The variations of the renormalization shielding effects on the electron-impact ionization cross section are also discussed.

  2. Ionizing radiation and non-ionizing radiation in educational environment

    International Nuclear Information System (INIS)

    By chance, we measured gamma dose rates in our school, and around the JCO Tokai Plant during the criticality on September 30 in 1999, with our GM survey meter. At that time, we made sure to estimate the position of criticality reaction (source point), and the source intensity of criticality reaction, with our own data, measured along the public roads, route 6 and local road 62. The intensity of gamma dose rates along the road was analyzed as Lorentz functions. At the time, there were no environmental radiation data about the criticality accident, or all the data, especially radioactivity and dose rates around the JCO Tokai Plant, was closed to the public. Recently, we are interested in the intensity of non-ionizing radiation, especially extremely low frequency (ELF) magnetic field, and electric field, in our environment. We adopted the same method to analyze the source position and source intensity of an ELF magnetic field and electric behind a wall. (author)

  3. Ionization caused by β-emitters and its applications

    International Nuclear Information System (INIS)

    Ionization caused by β-decay of hydrogen-3 (tritium) and strontium-90 has been studied by means of a pulse-counting mode of mass spectrometer. Radiation sources are a titanium plate (10 mm x 15 mm) carrying 150 mCi tritium in the form of titanium hydride, and a silver plate (12.5 mm2) with 5 mCi strontium-90 protected by an extremely thin layer of gold. Target materials are H2 and He gases with the natural abundance ratios. The dependence of the ion peak height on the gas pressure has been examined in the range of 10-4 to approximately 10-7 Torr, and two types of expression, linear and of cube root, were obtained. The mechanism of ion formation in this system is discussed, and its tempting applications are presented. (author)

  4. Desorption and ionization processes in laser mass spectrometry

    International Nuclear Information System (INIS)

    In this thesis results are reported from a study on the desorption- and ionization process initiated by infra-red laser irradiation (LDMS) or ion bombardment (SIMS) of thin organic sample layers. The study is especially focused on the formation of quasimolecular ions under these conditions. Results of these investigations can be used for a better optimization of the LDMS and SIMS techniques in organic mass spectrometry. First, an overview is given of laser desorption mass spectrometry. Next, the coupling of the laser energy into the organic sample layer is investigated. It is concluded that the laser energy is primarily absorbed by the substrate material and not by the organic overlayer. The formation of quasi-molecular ions, either in the gas phase or in the substrate surface is investigated. The final section reports kinetic energy distributions for ions sputtered from organic solids and liquids. (Auth.)

  5. Ionized carbon in side-illuminated molecular clouds

    International Nuclear Information System (INIS)

    The C II fine-structure line has been observed in five sources for which the ionization front/molecular cloud interface is viewed approximately edge-on. The LSR velocity of the C II emission is generally in good agreement with that observed for molecular species such as CO. However, the observed linewidths of 3-14 km/s are typically wider than those of molecular lines and often show rapid spatial variations in the observed regions. The C II brightness temperature are typically equal to or slightly higher than the dust temperature at all locations observed. In the optically thin approximation, C II excitation temperatures are 100 K or more and column densities are 10 to the 18th/sq cm for all sources except M17, which has a more intense and complicated line profile with a larger spatial extent than any other source observed. 58 refs

  6. Development and applications of ionization techniques in ambient mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Rejšek, Jan; Vrkoslav, Vladimír; Cvačka, Josef

    Brno : Institute of Analytical Chemistry AS CR, 2014 - (Foret, F.; Křenková, J.; Drobníková, I.; Guttman, A.; Klepárník, K.), s. 97-98 ISBN 978-80-904959-2-0. [CECE 2014. International Interdisciplinary Meeting on Bioanalysis /11./. Brno (CZ), 20.10.2014-22.10.2014] R&D Projects: GA ČR GP13-25137P; GA ČR GAP206/12/0750 Grant ostatní: GA AV ČR(CZ) M200551204 Institutional support: RVO:61388963 Keywords : ambient mass spectrometry * desorption electrospray ionization * desorption atmospheric pressure photoionization * thin-layer chromatography * insect defense compounds * mass spectrometry imaging Subject RIV: CB - Analytical Chemistry, Separation

  7. Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

    Energy Technology Data Exchange (ETDEWEB)

    Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

    2007-08-15

    The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained.

  8. Superconducting thin film vertex detector for SSC [Superconducting Super Collider] applications

    International Nuclear Information System (INIS)

    A possibly very-radiation-hard detector based on superconducting thin film strips is described. The interaction of the thin film detector with charged particles is discussed, and the feasibility of extending previous work on alpha-particle detection to the more stringent requirements for minimum ionizing particles is considered. A novel approach to the readout is briefly outlined which utilizes the slow phase velocity of electromagnetic waves possible in superconducting waveguides

  9. Social trust and ionizing radiation

    International Nuclear Information System (INIS)

    The linkages that exist between the environmental risks associated with nuclear energy production (both perceived and real) and the myriad of social and political issues and processes that influence social trust are a current issue in literature, but are not well explored, particularly for the Canadian context. This paper will examine one particular issue and its relationship with social trust: ionizing radiation and public health. Social trust is defined for this paper as including interpersonal trust, but having a much broader focus, extending to public trust in governments, institutions, corporations, and the power elite, and across whole societies. Of particular interest for the nuclear energy issue is how waning social trust may impact the functioning of democratic decision-making processes, particularly those associated with the siting of waste facilities. Social trust is a central issue in the management of environmental risks, particularly those related to high technology; its absence is seen as a major cause of intractable conflict in decisions related to nuclear power generation and waste disposal. Understanding the dynamics of social trust is important if a resolution is to be found to the nuclear waste management debate in Canada, that is, one that involves broad public, or social, support. For instance, what factors cause distrust to emerge, and when distrust emerges, what authorities do members of affected communities seek out for information and support? This paper begins to examine social trust in relation to human health and ionizing radiation, particularly low dose radiation from radioactive wastes resulting from uranium and radium processing activities in Port Hope, Ontario. These activities date back to the 1930s and are of great concern to community members. This paper looks at some of the roots of public concern, for example, scientific uncertainty around whether or not human health is compromised by exposure to low dose ionizing radiation

  10. Multiphoton ionization of uranium hexafluoride

    Science.gov (United States)

    Armstrong, D. P.; Harkins, D. A.; Compton, R. N.; Ding, D.

    1994-01-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy (TOFMS) and photoelectron spectroscopy (PES) studies of UF6 are reported using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF+x fragment ions, even at the lowest laser power densities at which signal could be detected. In general, the doubly charged uranium ion (U2+) intensity is much greater than that of the singly charged uranium ion (U+). For the case of the tunable dye laser experiments, the Un+ (n=1-4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The MPI-PES studies reveal only very slow electrons (≤0.5 eV) for all wavelengths investigated. The dominance of the U2+ ion, the absence or very small intensities of UF+x (x=1-3) fragments, the unstructured wavelength dependence, and the preponderance of slow electrons all indicate that mechanisms may exist other than ionization of bare U atoms following the stepwise photodissociation of F atoms from the parent molecule. The data also argue against stepwise photodissociation of UF+x (x=5,6) ions. Neither of the traditional MPI mechanisms (``neutral ladder'' or the ``ionic ladder'') are believed to adequately describe the ionization phenomena observed. We propose that the multiphoton excitation of UF6 under these experimental conditions results in a highly excited molecule, superexcited UF6**. The excitation of highly excited UF6** is proposed to be facilitated by the well known ``giant resonance,'' whose energy level lies in the range of 12-14 eV above that of ground state UF6. The highly excited molecule then primarily dissociates, via multiple channels, into Un+, UF+x, fluorine atoms, and ``slow'' electrons, although dissociation

  11. Ionization efficiency calculations for cavity thermoionization ion source

    International Nuclear Information System (INIS)

    The numerical model of ionization in a thermoionization ion source is presented. The review of ion source ionization efficiency calculation results for various kinds of extraction field is given. The dependence of ionization efficiency on working parameters like ionizer length and extraction voltage is discussed. Numerical simulations results are compared to theoretical predictions obtained from a simplified ionization model

  12. Basic study on FP gas monitoring with Resonance Ionization Spectroscopy

    International Nuclear Information System (INIS)

    Resonance Ionization Spectroscopy (RIS) has recently got into the spotlight as an innovative technology for ultra high sensitive trace element analysis and/or efficient isotope separation and is being developed into more extensive application in various engineering fields with improvement of tunable laser performance. The present study is aiming to develop a new and advanced Failed Fuel Detection and Location (FFDL) technique based on fission product (FP) gas (such as Kr and Xe) monitoring with Resonance Ionization Mass Spectrometry (RIMS), which combines RIS with mass spectrometry. Under collaborative works of advanced basic engineering research with JNC over four years since 1996, the feasibility study on the RIMS-FFDL have been made through basic experiments to detect Xe and Kr by using a RIMS system for common utilization installed at the Nuclear Engineering Research Laboratory of the University of Tokyo. This report describes the basic performance necessary to the design of RIMS-FFDL such as the detection limit, the elemental selectivity, etc. obtained from experiments and their theoretical analyses and also the successful results on the detection and isotopic ratio analysis of ppb level Xe/Kr tag gas in the cover gas sampled from the experimental fast reactor 'JOYO', which would lead to the conclusion that the RIMS-FFDL can satisfy all the requirements for conventional FFDL methods in addition to a novel function of no-line isotopic ratio analysis useful for the tag gas method adopted in the prototype fast reactor 'MONJU'. (author)

  13. Thin wall ductile and austempered iron castings

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2010-07-01

    Full Text Available It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns. Thin wall ductile iron castings can be lighter (380 g than their substitutes made of aluminium alloys (580g. The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dilatometic studies. It has been shown that in thin wall ductile iron castings austenitising at 880 oC for 20 minutes is adequate to obtain the austenite matrix at the end of the first stage of austempering heat treatment cycle.

  14. Radiation sensitivity of graphene field effect transistors and other thin film architectures

    Science.gov (United States)

    Cazalas, Edward

    An important contemporary motivation for advancing radiation detection science and technology is the need for interdiction of nuclear and radiological materials, which may be used to fabricate weapons of mass destruction. The detection of such materials by nuclear techniques relies on achieving high sensitivity and selectivity to X-rays, gamma-rays, and neutrons. To be attractive in field deployable instruments, it is desirable for detectors to be lightweight, inexpensive, operate at low voltage, and consume low power. To address the relatively low particle flux in most passive measurements for nuclear security applications, detectors scalable to large areas that can meet the high absolute detection efficiency requirements are needed. Graphene-based and thin-film-based radiation detectors represent attractive technologies that could meet the need for inexpensive, low-power, size-scalable detection architectures, which are sensitive to X-rays, gamma-rays, and neutrons. The utilization of graphene to detect ionizing radiation relies on the modulation of graphene charge carrier density by changes in local electric field, i.e. the field effect in graphene. Built on the principle of a conventional field effect transistor, the graphene-based field effect transistor (GFET) utilizes graphene as a channel and a semiconducting substrate as an absorber medium with which the ionizing radiation interacts. A radiation interaction event that deposits energy within the substrate creates electron-hole pairs, which modify the electric field and modulate graphene charge carrier density. A detection event in a GFET is therefore measured as a change in graphene resistance or current. Thin (micron-scale) films can also be utilized for radiation detection of thermal neutrons provided nuclides with high neutron absorption cross section are present with appreciable density. Detection in thin-film detectors could be realized through the collection of charge carriers generated within the

  15. Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12

    Science.gov (United States)

    Schalk, Oliver; Josefsson, Ida; Richter, Robert; Prince, Kevin C.; Odelius, Michael; Mucke, Melanie

    2015-10-01

    In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M3(CO)12 with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M—CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M3(CO)12 are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru3(CO)12.

  16. Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12

    International Nuclear Information System (INIS)

    In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M3(CO)12 with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M—CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M3(CO)12 are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru3(CO)12

  17. Sodium ionization detector and sensor

    International Nuclear Information System (INIS)

    Work conducted on a basic technology development effort with the Westinghouse Sodium Ionization Detector (SID) sensor is reported. Included are results obtained for three task areas: (1) On-line operational response testing - in-situ calibration techniques; (2) Performance-reliability characteristics of aged filaments; and (3) Evaluation of chemical interference effects. The results showed that a calibrator filament coated with a sodium compound, when activated, does supply the necessary sodium atoms to provide a valid operational in-situ test. The life time of new Cr203-protected SID sensor filaments can be extended by operating at a reduced temperature. However, there also is a reduction in the sensitivity. Non-sodium species, such as products from a smoldering fire and organic aerosols, produce an interference response from the sensor comparable to a typical sodium response

  18. Ionization tube simmer current circuit

    Science.gov (United States)

    Steinkraus, Jr., Robert F.

    1994-01-01

    A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current.

  19. Ionization in nearby interstellar gas

    Science.gov (United States)

    Frisch, P. C.; Welty, D. E.; York, D. G.; Fowler, J. R.

    1990-01-01

    Due to dielectric recombination, neutral magnesium represents an important tracer for the warm low-density gas around the solar system. New Mg I 2852 absorption-line data from IUE are presented, including detections in a few stars within 40 pc of the sun. The absence of detectable Mg I in Alpha CMa and other stars sets limits on the combined size and electron density of the interstellar cloud which gives rise to the local interstellar wind. For a cloud radius greater than 1 pc and density of 0.1/cu cm, the local cloud has a low fractional ionization, n(e)/n(tot) less than 0.05, if magnesium is undepleted, equilibrium conditions prevail, the cloud temperature is 11,750 K, and 80 percent of the magnesium in the sightline is Mg II.

  20. Ionizing radiations and oxidizing stress

    International Nuclear Information System (INIS)

    The normal cell metabolism produces continuously reactive oxygenated species which sometimes are not completely transformed and can lead to a highly reactive form of oxygen: the superoxide anion (characteristic of free radicals). These aggressive molecules are normally eliminated by the enzymatic and biochemical defense systems, but some external factors, like the ionizing radiations, can accelerate their production and saturate the natural defense systems. Such a situation leads to a disorganization of the membrane structures, to the oxidation of the lipo-proteins and proteins and to a degradation and fragmentation of DNA. This oxidative stress affects all kind of tissues and metabolisms and thus participates to a large number of pathologies, in particular cancers. (J.S.)

  1. Non-ionizing radiation detection

    International Nuclear Information System (INIS)

    sensors network for non-ionizing radiation detection in the band of 800 MHz to 2.5 GHz was designed and constructed. The system is based on a sensor which shows an output DC voltage proportional to the input RF signal. This network is made of four broad band antennas, four circuit board sensors, a main board and data visualization software. The performance system was analyzed changing its configuration and using several radiation sources. The results presented include the simulation of an Archimedes antenna using CST STUDIOTM and the experimental results of a broad band HG2404CU antenna. The results have shown an efficient system for the electromagnetic radiation detection. As a second part of this work, this prototype will be used as a detector of cellular phone calls in places where they are not allowed such as prisons, banks and so on.

  2. Modeling of associative ionization reactions in hypersonic rarefied flows

    Science.gov (United States)

    Boyd, Iain D.

    2007-09-01

    When vehicles reenter the Earth's atmosphere from space, the hypersonic conditions are sufficiently energetic to generate ionizing reactions. The production of a thin plasma layer around a hypersonic vehicle can block radio waves sent to and from the vehicle, leading to communications blackout. For Earth entry from orbit, the maximum energy involved in molecular collisions requires only associative ionization of air-species to be considered. In the present study, the modeling of such reactions is considered in detail using the direct simulation Monte Carlo (DSMC) method. For typical Earth entry conditions, with a velocity near 8km/s, it is shown that the average ionizing reaction probabilities are small. Special numerical techniques must therefore be used in the DSMC technique in order to numerically resolve these reactions. Additional simulation problems arise from the relatively small mass of the electrons in comparison to the other atoms and molecules in these flow fields. Artificially increasing the electron mass greatly increases computational efficiency, and the viability of this approach is investigated. Simulation results are presented for conditions corresponding to the RAM-C II hypersonic flight experiment that gathered measurements of electron number density. It is demonstrated that simulation results for electron number density in this energy regime are relatively insensitive to the mass of the electrons. Direct comparison of DSMC results with the RAM-C II measurements for electron number density shows excellent agreement. These satisfactory comparisons represent the first direct verification of the ability of the DSMC technique to successfully predict the weak plasma generated around a hypersonic vehicle.

  3. A search for ionized jets towards massive young stellar objects

    CERN Document Server

    Purser, S J D; Hoare, M G; Urquhart, J S; Cunningham, N; Purcell, C R; Brooks, K J; Garay, G; Gúzman, A E; Voronkov, M A

    2016-01-01

    Radio continuum observations using the Australia telescope compact array at 5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45 of 49 massive young stellar objects and HII regions. Of these, 26 sources are classified as ionized jets (12 of which are candidates), 2 as ambiguous jets or disc winds, 1 as a disc-wind, 14 as HII regions and 2 were unable to be categorised. Classification as ionized jets is based upon morphology, radio flux and spectral index, in conjunction with previous observational results at other wavelengths. Radio-luminosity and momentum are found to scale with bolometric luminosity in the same way as low-mass jets, indicating a common mechanism for jet production across all masses. In 13 of the jets, we see associated non-thermal/optically-thin lobes resulting from shocks either internal to the jet and/or at working surfaces. Ten jets display non-thermal (synchrotron emission) spectra in their lobes, with an average spectral index of -0.55 consistent with Fermi a...

  4. Advances in nuclear science and technology

    CERN Document Server

    Greebler, Paul

    1968-01-01

    Advances in Nuclear Science and Technology Volume 4 provides information pertinent to the fundamental aspects of advanced reactor concepts. This book discusses the advances in various areas of general applicability, including modern perturbation theory, optimal control theory, and industrial application of ionizing radiations.Organized into seven chapters, this volume begins with an overview of the technology of sodium-cooled fast breeder power reactors and gas-cooled power reactors. This text then examines the key role of reactor safety in the development of fast breeder reactors. Other chapt

  5. Development of High Resolution Resonance Ionization Mass Spectrometry for Neutron Dosimetry Technique with93Nb(n,n')93mNb Reaction

    Science.gov (United States)

    Tomita, Hideki; Takatsuka, Takaaki; Takamatsu, Takahide; Adachi, Yoshitaka; Furuta, Yujin; Noto, Takuma; Iguchi, Tetsuo; Sonnenschein, Volker; Wendt, Klaus; Ito, Chikara; Maeda, Shigetaka

    2016-02-01

    We have proposed an advanced technique to measure the 93mNb yield precisely by Resonance Ionization Mass Spectrometry, instead of conventional characteristic X-ray spectroscopy. 93mNb-selective resonance ionization is achievable by distinguishing the hyperfine splitting of the atomic energy levels between 93Nb and 93mNb at high resolution. In advance of 93mNb detection, we could successfully demonstrate high resolution resonant ionization spectroscopy of stable 93Nb using an all solid-state, narrow-band and tunable Ti:Sapphire laser system operated at 1 kHz repetition rate.

  6. Strong Turbulence in Partially Ionized Plasmas

    DEFF Research Database (Denmark)

    Mikkelsen, Torben; Pécseli, Hans

    1980-01-01

    Experimental investigations of strong turbulence in partially ionized, low-β plasmas are reported. The observed spectra are interpreted by applying Taylor's hypothesis and related to turbulent fluctuations in the ionosphere.......Experimental investigations of strong turbulence in partially ionized, low-β plasmas are reported. The observed spectra are interpreted by applying Taylor's hypothesis and related to turbulent fluctuations in the ionosphere....

  7. Multicomponent transport in weakly ionized mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Giovangigli, V [CMAP, CNRS, Ecole Polytechnique, 91128 Palaiseau (France); Graille, B [Laboratoire de Mathematiques, Universite Paris-Sud, 91405, Orsay (France); Magin, T [Center for Turbulence Research, Stanford University, CA 94305 (United States); Massot, M, E-mail: vincent.giovangigli@polytechnique.f [Laboratoire EM2C, Ecole Centrale de Paris, 92295 Chatenay-Malabry (France)

    2010-06-15

    We discuss transport coefficients in weakly ionized mixtures. We investigate the situations of weak and strong magnetic fields as well as electron temperature nonequilibrium. We present in each regime the Boltzmann equations, examples of transport fluxes, the structure of transport linear systems and discuss their solution by efficient iterative techniques. Numerical simulations are presented for partially ionized high-temperature air.

  8. Basics of the ionizing radiation dosimetry

    International Nuclear Information System (INIS)

    The dosimetry basic physics issues, ionizing irradiation interaction with the substance and the radiation parameter regulation principles were considered. The special attention was paid to the methods of the ionizing radiation measurement. The edition is the manual on the dosimetry principles and is intended, first of all, for the university students of the technical and engineering specialties

  9. Ionization in antiproton-hydrogen collisions

    International Nuclear Information System (INIS)

    Employing the semiclassical approximation we calculate within the coupled-state formalism the ionization probability in antiproton-hydrogen (anti p+H) collisions. In particular we investigate the adiabatic ionization at the distance of closest approach in almost central collisions. Striking differences in the electron excitation probability compared with proton-hydrogen (p+H) collisions are predicted. (orig.)

  10. MICE: The International Muon Ionization Cooling Experiment

    CERN Document Server

    Kaplan, D M

    2006-01-01

    Ionization cooling of a muon beam is a key technique for a Neutrino Factory or Muon Collider. An international collaboration is mounting an experiment to demonstrate muon ionization cooling at the Rutherford Appleton Laboratory. We aim to complete the experiment by 2010.

  11. Advances in radiation processing of polymeric materials

    International Nuclear Information System (INIS)

    In this paper we review recent advances in industrial applications of electron-beam irradiation in the field of polymer processing at the Takasaki Radiation Chemistry Research Establishment (TRCRE) of JAERI (Japan Atomic Energy Research Institute), and the Whiteshell Laboratories of AECL Research, Canada. Irradiation of a substrate with ionizing radiation produces free radicals through ionization and excitation events. The subsequent chemistry of these radicals is used in radiation processing as a substitute for conventional processing techniques based on heating and/or the addition of chemicals. The advantages of radiation processing include the formation of novel products with desirable material properties, favourable overall process economics and, often, environmental benefits

  12. nvestigation on influencing factors in determination of hydrocarbons in heavy oils by thin-layer chromatography flame/ionization detector.%棒状薄层色谱/氢火焰离子化检测器法测定重油烃族组成影响因素的探讨

    Institute of Scientific and Technical Information of China (English)

    杨海鹰; 顾洁; 蔺玉贵

    2001-01-01

    The influencing factors in the determination of hydrocarbons (saturates, aromatics, resins) in heavy oils by thin layer chromatography/flame ionization detection (TLC/FID) were investigated. It has been found that the solvent co -volatization may cause sample loss during the spotting and developing process, and that the quantitative calibration factors can not be used universally. Because the flame temperature of TLC/FLD is much lower than that of GC/FID, the transformation of different compounds in the flame of FID is varied.%对应用棒状薄层色谱/氢火焰离子化检测器(TLC/FID)测定重油烃族组成(饱和烃、芳烃、胶质)时的影响因素作了探讨。研究发现,在点样及展开过程中,溶剂共挥发可引起样品损失;而且,由于TLC/FID的火焰温度远低于一般GC条件下FID的火焰温度,使不同化合物在FID上的燃烧转化情况有差异,因而其定量校正因子不具有通用性。

  13. Ionization of atomic oxygen by protons

    International Nuclear Information System (INIS)

    A crossed-beam technique incorporating time-of-flight analysis and coincidence counting of the collision products, recently used in this laboratory to study one-electron capture in collisions of H+ ions with ground-state oxygen atoms, has been adapted to allow measurements of the corresponding cross sections for ionization for the first time. Cross sections for the single ionization of O atoms have been determined within the range 34-100 keV. These cross sections pass through a peak value at an energy of about 60 keV. At higher energies, the process of ionization rather than electron capture becomes the main source of O+ production. On+ formation for n > 2 was too small to detect in the energy range considered. It is also shown that although production of O2+ through transfer ionization is quite significant, the yield of O2+ from pure ionization is unimportant. (author)

  14. Ionization Scheme Development at the ISOLDE RILIS

    Science.gov (United States)

    Fedosseev, V. N.; Marsh, B. A.; Fedorov, D. V.; Köster, U.; Tengborn, E.

    2005-04-01

    The resonance ionization laser ion source (RILIS) of the ISOLDE on-line isotope separation facility is based on the method of laser step-wise resonance ionization of atoms in a hot metal cavity. The atomic selectivity of the RILIS complements the mass selection process of the ISOLDE separator magnets to provide beams of a chosen isotope with greatly reduced isobaric contamination. Using a system of dye lasers pumped by copper vapour lasers, ion beams of 24 elements have been generated at ISOLDE with ionization efficiencies in the range of 0.5-15%. As part of the ongoing RILIS development off-line resonance ionization spectroscopy studies carried out in 2003 and 2004 have determined the optimal three-step ionization schemes for scandium, antimony, dysprosium and yttrium.

  15. Ionization Scheme Development at the ISOLDE RILIS

    International Nuclear Information System (INIS)

    The resonance ionization laser ion source (RILIS) of the ISOLDE on-line isotope separation facility is based on the method of laser step-wise resonance ionization of atoms in a hot metal cavity. The atomic selectivity of the RILIS complements the mass selection process of the ISOLDE separator magnets to provide beams of a chosen isotope with greatly reduced isobaric contamination. Using a system of dye lasers pumped by copper vapour lasers, ion beams of 24 elements have been generated at ISOLDE with ionization efficiencies in the range of 0.5-15%. As part of the ongoing RILIS development off-line resonance ionization spectroscopy studies carried out in 2003 and 2004 have determined the optimal three-step ionization schemes for scandium, antimony, dysprosium and yttrium.

  16. Advances in information storage systems

    CERN Document Server

    Bhushan, Bharat

    1995-01-01

    The series Advances in Information Storage Systems covers a wide range of interdisciplinary technical areas, related to magnetic or optical storage systems. The following nonexhaustive list is indicative of the scope of the topics: Friction, Adhesion, Wear and Lubrications, Coatings, Solid Mechanics, Air Flow, Contamination, Instrumentation, Dynamics, Shock and Vibration, Controls, Head and Suspension Design, Actuators, Spindle and Actuator Motors and Bearings, Structure of Thin Films, Corrosion, Long-Term Reliability, Materials and Processing, Manufacturing and Automation, Economics.This volu

  17. Positronium formation and ionization in slow positron-hydrogen atom collisions

    International Nuclear Information System (INIS)

    The electron capture and ionization processes in slow collisions of positrons with hydrogen atoms are considered within the advanced adiabatic approach to atomic collisions. The mass asymmetry of the (p,e-,e+) collision system is properly taken into account. The calculated positronium formation and ionization cross sections compare favourably with the available experimental data in the adiabatic energy region. It is shown that the potential energy curve of the 2p σ molecular state supports a quasi-bound level of the three-particle (p,e+,e-) system with an energy of -0.3 eV and decay width of 0.15 eV, approximately. (author)

  18. Electron impact ionization and multiphoton ionization of doped superfluid helium droplets: A comparison.

    Science.gov (United States)

    He, Yunteng; Zhang, Jie; Kong, Wei

    2016-02-28

    We compare characteristics of electron impact ionization (EI) and multiphoton ionization (MPI) of doped superfluid helium droplets using the same droplet source. Selected dopant ion fragments from the two ionization schemes demonstrate different dependence on the doping pressure, which could be attributed to the different ionization mechanisms. While EI directly ionizes helium atoms in a droplet therefore has higher yields for bigger droplets (within a limited size range), MPI is insensitive to the helium in a droplet and is only dependent on the number of dopant molecules. The optimal timing of the ionization pulse also varies with the doping pressure, implying a velocity slip among different sized droplets. Calculations of the doping statistics and ionization probabilities qualitatively agree with the experimental data. Our results offer a word of caution in interpreting the pressure and timing dependence of superfluid helium droplets, and we also devise a scheme in achieving a high degree of doping while limiting the contribution of dopant clusters. PMID:26931697

  19. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    International Nuclear Information System (INIS)

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12±1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3xω Nd:YAG laser in air, SF6 or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to ∼2 μm in SF6 gas and to ∼5 μm in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

  20. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

    2007-04-15

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12{+-}1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3x{omega} Nd:YAG laser in air, SF{sub 6} or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

  1. Radiation protection training for users of ionizing radiation in Hungary

    International Nuclear Information System (INIS)

    According to the current and previous regulation related to the safety use of ionizing radiation, the personnel involved must obtain special qualification in radiation protection. In Hungary the radiation protection training are performed by appropriately certified training centers on basic, advanced and comprehensive levels. Certification of the training centers is given by the competent radiological health/radiation protection authority. The office of the Chief Medical Officer is the certifying authority for advanced and comprehensive levels training, as well as competent Regional Radiological Health Authority is responsible for basic level courses. The content and length of courses are specified in the regulation for all three levels of industrial, laboratory and medical users, in general. Some of the universities, technical and medical oriented are certified for advanced training for students as gradual course. Recently in Hungary there are 47 certified training centers for advanced and comprehensive courses, where the trainers should have a five years job experience in radiation protection and successful completion of comprehensive level course in radiation protection. (authors)

  2. Advanced Optical Metrology for XRAY Replication Mandrels and Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced x-ray observatories such as IXO and GenX will require thousands of thin shell mirror segments produced by replication using convex mandrels. Quality and...

  3. Modeling of thin-film solar thermoelectric generators

    OpenAIRE

    Weinstein, Lee Adragon; McEnaney, Kenneth; Chen, Gang

    2013-01-01

    Recent advances in solar thermoelectric generator (STEG) performance have raised their prospect as a potential technology to convert solar energy into electricity. This paper presents an analysis of thin-film STEGs. Properties and geometries of the devices are lumped into two parameters which are optimized to guide device design. The predicted efficiencies of thin-film STEGs are comparable to those of existing STEG configurations built on bulk materials.

  4. Ionization Cooling using Parametric Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland P.

    2008-06-07

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  5. Ionization Cooling using Parametric Resonances

    International Nuclear Information System (INIS)

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  6. ADVANCE PAYMENTS

    CERN Multimedia

    Human Resources Division

    2002-01-01

    Administrative Circular Nº 8 makes provision for the granting of advance payments, repayable in several monthly instalments, by the Organization to the members of its personnel. Members of the personnel are reminded that these advances are only authorized in exceptional circumstances and at the discretion of the Director-General. In view of the current financial situation of the Organization, and in particular the loans it will have to incur, the Directorate has decided to restrict the granting of such advances to exceptional or unforeseen circumstances entailing heavy expenditure and more specifically those pertaining to social issues. Human Resources Division Tel. 73962

  7. Advance payments

    CERN Multimedia

    Human Resources Division

    2003-01-01

    Administrative Circular N 8 makes provision for the granting of advance payments, repayable in several monthly instalments, by the Organization to the members of its personnel. Members of the personnel are reminded that these advances are only authorized in exceptional circumstances and at the discretion of the Director-General. In view of the current financial situation of the Organization, and in particular the loans it will have to incur, the Directorate has decided to restrict the granting of such advances to exceptional or unforeseen circumstances entailing heavy expenditure and more specifically those pertaining to social issues. Human Resources Division Tel. 73962

  8. Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

    DEFF Research Database (Denmark)

    Andersen, Jens S.; Svensson, B; Roepstorff, P

    1996-01-01

    Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is...

  9. Lipids of the ultra-thin square halophilic archaeon Haloquadratum walsbyi

    OpenAIRE

    Simona LoBasso; Patrizia LoPalco; Giuseppe Mascolo; Angela Corcelli

    2008-01-01

    The lipid composition of the extremely halophilic archaeon Haloquadratum walsbyi was investigated by thin-layer chromatography and electrospray ionization-mass spectrometry. The analysis of neutral lipids showed the presence of vitamin MK-8, squalene, carotene, bacterioruberin and several retinal isomers. The major polar lipids were phosphatidylglycerophosphate methyl ester, phosphatidylglycerosulfate, phosphatidylg...

  10. Nanocoatings and ultra-thin films technologies and applications

    CERN Document Server

    Tiginyanu, Ion

    2011-01-01

    Gives a comprehensive account of the developments of nanocoatings and ultra-thin films. This book covers the fundamentals, processes of deposition and characterisation of nanocoatings, as well as the applications. It is suitable for the glass and glazing, automotive, electronics, aerospace, construction and biomedical industries in particular.$bCoatings are used for a wide range of applications, from anti-fogging coatings for glass through to corrosion control in the aerospace and automotive industries. Nanocoatings and ultra-thin films provides an up-to-date review of the fundamentals, processes of deposition, characterisation and applications of nanocoatings. Part one covers technologies used in the creation and analysis of thin films, including chapters on current and advanced coating technologies in industry, nanostructured thin films from amphiphilic molecules, chemical and physical vapour deposition methods and methods for analysing nanocoatings and ultra-thin films. Part two focuses on the applications...

  11. Photoelectron angular distributions from two-photon ionization of atoms near ionization threshold

    Institute of Scientific and Technical Information of China (English)

    Lihua Bai; Tingting Cui; Yuheng Liu; Yan Wang; Dongmei Deng; Jihui Tao

    2011-01-01

    @@ Photoelectron angular distributions (PADs) from two-photon ionization of atoms in linearly polarized strong laser fields are obtained in accordance with the nonperturbative quantum scattering theory. We also study the influence of laser wavelength on PADs. For two-photon ionization very close to the ionization threshold, most of the ionized electrons are vertically ejected to the laser polarization. PADs from twophoton ionization of atoms are determined by the second order generalized phased Bessel function at which the ponderomotive parameter plays a key role. In terms of dependence of PADs on laser wavelength,corresponding variations for the ponderomotive parameter are demonstrated.%Photoelectron angular distributions (PADs) from two-photon ionization of atoms in linearly polarized strong laser fields are obtained in accordance with the nonperturbative quantum scattering theory. We also study the influence of laser wavelength on PADs. For two-photon ionization very close to the ionization threshold, most of the ionized electrons are vertically ejected to the laser polarization. PADs from twophoton ionization of atoms are determined by the second order generalized phased Bessel function at which the ponderomotive parameter plays a key role. In terms of dependence of PADs on laser wavelength,corresponding variations for the ponderomotive parameter are demonstrated.

  12. Exposure to non ionizing radiations

    International Nuclear Information System (INIS)

    In the last years the exposure levels to electric, magnetic and electromagnetic fields of workers and citizens have dramatically increased due to the technological development as in the exemplar case of cellular phones. The object of this research concerns the biological evaluation of the risk from exposure to non ionizing radiations (NIR) by an opportunely designed biosensor based on immobilized Saccharomyces cerevisiae cells and by an amperometric transducer (Clark oxygen electrode). The results have been obtained by comparing the respiratory activities of exposed and not exposed yeast cells to NIR (at 900 MHz, frequency of the first generation cellular phones). The measurements have been performed by irradiation of the cells in a G-TEM chamber. The obtained results clearly show a decrease of the respiration activity of the irradiation cells in comparison with blank. This variation results to be proportional to the exposure time. Concerning reversibility of the damage it seems that the recovery of the initial conditions begins after 4 hours since the end of exposition and is complete within the following 48 hrs

  13. Biological Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    The aim of this work is to verify the existence of the adaptive response phenomenon induced by low doses of ionizing radiation in living cells.A wild-type yeast Saccharomyces cerevisiae (Baker's yeast) was chosen as the biological target.As a parameter to quantify the sensibility of the target to radiation, the Lethal Dose 50 (LD50 ) was observed. In our experimental condition a value of (60 ± 1) Gy was measured for LD50 with Dose Rate of (0.44 ± 0.03) Gy/min. The method employed to show up the adaptive response phenomenon consisted in exposing the sample to low ''conditioning'' doses, which would initiate these mechanisms. Later the samples with and without conditioning were exposed to higher ''challenging'' doses (such as LD50), and the surviving fractions were compared. In order to maximize the differences, the doses and the time between irradiations were varied. The best results were obtained with both a conditioning dose of (0.44 ± 0.03) Gy and a waiting time of 2 hs until the application of the challenging dose. Following this procedures the 80% of the conditioned samples has survived, after receiving the application of the LD50. The adaptive response phenomenon was also verified for a wide range of challenging doses

  14. Ion and electron impact ionization cross sections

    International Nuclear Information System (INIS)

    Several current projects are described in which cross sections of interest to radiation physics are being measured. These include total and multiple ionization cross sections for protons on several gases covering a wide energy range, the measurement of cross sections differential in the angle and energy of ejected electrons for several gases including water vapor, and a review of proton ionization data. The work on water vapor has also been extended to electron and neutral hydrogen impact. A brief discussion is also given of some systematics of ionization cross sections. 13 references

  15. Thermochromic behaviors and ionization potentials of organopolysilanes

    Science.gov (United States)

    Yokoyama, Kenji; Yokoyama, Masaaki

    1989-04-01

    Ionization potentials of organopolysilanes with different kinds of substituents were evaluated from the low energy photo-electron emission measurements in air. An aryl-substituted organopolysilane capable of σ - π mixing between Si backbone σ and side-group π electrons gave smaller ionization potential by about 0.1˜0.15 eV compared with alkyl-substituted organopolysilanes. The value of ionization potentials in some alkyl-substituted organopolysilanes which showed thermochromic behaviors was found to vary substantially with thermally induced reversible changes in polymer backbone conformation, indicating that the effective conjugation length of σ electrons decreases above the thermochromic transition temperature.

  16. Intense-field multiphoton ionization of helium

    International Nuclear Information System (INIS)

    The dynamics of multiphoton ionization of helium are investigated through numerical integration of the two-electron time-dependent Schroedinger equation. Using this work as a benchmark, a new single-active-electron model is introduced that gives agreement with He ionization rates to within a few per cent on average, and gives good agreement with He harmonic generation spectra over a laser intensity range of 0.5x1014 to 8.0x1014 W cm-2, and frequencies corresponding to four- and five-photon ionization. (author). Letter-to-the-editor

  17. A study of Alfven's ionizing critical velocity

    International Nuclear Information System (INIS)

    Alfven's hypothesis of the ionizing critical velocity is investigated on the basis of observations with rotating plasma devices. The experimental fact is that the relative velocity between a neutral gas and a plasma perpendicular to a magnetic field does not exceed a critical velocity vc = √2eVi/m (eVi and m, the ionization energy and the atomic or molecular mass of the gas, respectively). It is interpreted from the standpoint of a current which generates in a process of plasma polarization. A final interpretation on the hypothesis is not given, but the structure and elementary process of the ionizing interaction is clarified. (author)

  18. Re-ionization and decaying dark matter

    Science.gov (United States)

    Dodelson, Scott; Jubas, Jay M.

    1991-01-01

    Gunn-Peterson tests suggest that the Universe was reionized after the standard recombination epoch. A systematic treatment is presented of the ionization process by deriving the Boltzmann equations appropriate to this regime. A compact solution for the photon spectrum is found in terms of the ionization ratio. These equations are then solved numerically for the Decaying Dark Matter scenario, wherein neutrinos with mass of order 30 eV radiatively decay producing photons which ionize the intergalactic medium. It was found that the neutrino mass and lifetime are severely constrained by Gunn-Peterson tests, observations of the diffuse photon spectrum in the ultraviolet regime, and the Hubble parameter.

  19. Probing Angular Correlations in Sequential Double Ionization

    International Nuclear Information System (INIS)

    We study electron correlation in sequential double ionization of noble gas atoms and HCl in intense, femtosecond laser pulses. We measure the photoelectron angular distributions of Ne+ relative to the first electron in a pump-probe experiment with 8 fs, 800 nm, circularly polarized laser pulses at a peak intensity of a few 1015 W/cm2. Using a linear-linear pump-probe setup, we further study He, Ar, and HCl. We find a clear angular correlation between the two ionization steps in the sequential double ionization intensity regime.

  20. Ionized Gas in the Smith Cloud

    OpenAIRE

    Hill, Alex S.; Haffner, L. Matthew; Reynolds, Ronald J.

    2009-01-01

    We present WHAM observations of Halpha, [N II], and [S II] in the Smith Cloud. A map of Halpha emission from the cloud shows ionized gas coincident with the brightest H I emission, but nearly-as-bright Halpha in some regions with faint H I. The ionized mass of the cloud is at least as large as the neutral mass, > 10^6 M_sun. Ionized gas in the core of the Smith Cloud has an electron temperature 6000 K < T < 16000 K. The observed ratio [N II] / Halpha = 0.39 \\pm 0.09 shows that the cloud has a...

  1. Electron impact single ionization of copper

    Indian Academy of Sciences (India)

    L K Jha; O P Roy; B N Roy

    2000-09-01

    Electron impact single ionization cross sections of copper have been calculated in the binary encounter approximation using accurate expression for as given by Vriens and Hartree–Fock momentum distribution for the target electron. The BEA calculation based on the usual procedure does not show satisfactory agreement with experiment in this case but a striking modification is found to be successful in explaining the experimental observations. The discrepancy is linked with the ionization of the 310 electrons and probably effective single ionization does not take place from 3 shell of copper leading to smaller values of experimental cross sections.

  2. Ionizing photon budget: constraints from galaxies

    Science.gov (United States)

    Östlin, Göran

    2015-08-01

    I will discuss the the production and propagation of ionizing photons in galaxies. Multi wavelength HST imaging and spectroscopy of local starbursts, including candidate Lyman continuum leakers, from the UV to the i-band plus Halpha and Hbeta are used to investigate where ionizing protons are produced and absorbed. We add IFU data, e.g. from MUSE, to further constrain the optical depth to Lyman continuum photons. I will further discuss rest frame UV observations of galaxies at higher redshifts, and their implications for the ionizing photon budget.

  3. Non-equilibrium ionized blast wave

    Science.gov (United States)

    Wu, S. T.

    1974-01-01

    The structure of a cylindrical blast wave with ionization at non-LTE conditions was calculated using equations previously developed by Wu and Fu (1970). The degree of ionization was predicted by a modified Saha equation. Temperature profiles show that the temperature at non-LTE conditions is lower than at LTE near the shock front. This corresponds to a higher degree of ionization for the non-LTE limit, which indicates that the neutral gas absorption is much more efficient at non-LTE than at the LTE limit. The decaying velocity under non-LTE is approximately 15% less than under LTE.

  4. Advanced Microsensors

    Science.gov (United States)

    1991-01-01

    This video looks at a spinoff application of the technology from advanced microsensors -- those that monitor and determine conditions of spacecraft like the Space Shuttle. The application featured is concerned with the monitoring of the health of premature babies.

  5. Assembly and Applications of Carbon Nanotube Thin Films

    Institute of Scientific and Technical Information of China (English)

    Hongwei ZHU; Bingqing WEI

    2008-01-01

    The ultimate goal of current research on carbon nanotubes (CNTs) is to make breakthroughs that advance nanotechnological applications of bulk CNT materials. Especially, there has been growing interest in CNT thin films because of their unique and usually enhanced properties and tremendous potential as components for use in nano-electronic and nano-mechanical device applications or as structural elements in various devices. If a synthetic or a post processing method can produce high yield of nanotube thin films, these structures will provide tremendous potential for fundamental research on these devices. This review will address the synthesis, the post processing and the device applications of self-assembled nanotube thin films.

  6. Advanced nanoelectronics

    CERN Document Server

    Ismail, Razali

    2012-01-01

    While theories based on classical physics have been very successful in helping experimentalists design microelectronic devices, new approaches based on quantum mechanics are required to accurately model nanoscale transistors and to predict their characteristics even before they are fabricated. Advanced Nanoelectronics provides research information on advanced nanoelectronics concepts, with a focus on modeling and simulation. Featuring contributions by researchers actively engaged in nanoelectronics research, it develops and applies analytical formulations to investigate nanoscale devices. The

  7. 3D Modeling of Laser Propagation in Ionizing Gas and Plasma

    Science.gov (United States)

    Cooley, J.; Antonsen, T., Jr.; Huang, C.; Mori, W.

    2003-10-01

    The interaction of a high intensity laser with ionizing gas and plasmas is of current interest for both Laser Wakefield Accelerators and x-ray generation. We have developed a 3D fluid simulation code based on the same quasistatic approximation used in the 2D code WAKE [1]. The object oriented structure of the code also allows it to couple to the quickPIC particle code [2]. We will present 3D studies of the ionization scattering instability [3], which occurs when a laser pulse propagates in an ionizing gas. [1] P. Mora and T. Antonsen, Jr., Phys. Plasmas 4(1), January 1997 [2] J. Cooley, T. Antonsen, Jr., C. Huang, etal., Proceedings, Advanced Accelerator Concepts, 2002 [3] Z. Bian and T. Antonsen, Jr., Phys. Plasmas 8(7), July 2001 * work supported by NSF and DOE

  8. AdvancED Flex 4

    CERN Document Server

    Tiwari, Shashank; Schulze, Charlie

    2010-01-01

    AdvancED Flex 4 makes advanced Flex 4 concepts and techniques easy. Ajax, RIA, Web 2.0, mashups, mobile applications, the most sophisticated web tools, and the coolest interactive web applications are all covered with practical, visually oriented recipes. * Completely updated for the new tools in Flex 4* Demonstrates how to use Flex 4 to create robust and scalable enterprise-grade Rich Internet Applications.* Teaches you to build high-performance web applications with interactivity that really engages your users.* What you'll learn Practiced beginners and intermediate users of Flex, especially

  9. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  10. Thinning Invariant Partition Structures

    CERN Document Server

    Starr, Shannon

    2011-01-01

    A partition structure is a random point process on $[0,1]$ whose points sum to 1, almost surely. In the case that there are infinitely many points to begin with, we consider a thinning action by: first, removing points independently, such that each point survives with probability $p>0$; and, secondly, rescaling the remaining points by an overall factor to normalize the sum again to 1. We prove that the partition structures which are "thinning divisible" for a sequence of $p$'s converging to 0 are mixtures of the Poisson-Kingman partition structures. We also consider the property of being "thinning invariant" for all $p \\in (0,1)$.

  11. The critical ionization velocity - a bibliography

    International Nuclear Information System (INIS)

    A list of all relevant contributions, known to the authors, concerning the critical ionization velocity phenomena is presented. The contributions are classified and described in a few sentences. (Authors)

  12. High-Temperature Ionization in Protoplanetary Disks

    CERN Document Server

    Desch, Steven J

    2015-01-01

    We calculate the abundances of electrons and ions in the hot (> 500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains' work functions. The charged species' abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks' dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge locat...

  13. Electron impact ionization of large krypton clusters

    Institute of Scientific and Technical Information of China (English)

    Li Shao-Hui; Li Ru-Xin; Ni Guo-Quan; Xu Zhi-Zhan

    2004-01-01

    We show that the detection of ionization of very large van der Waals clusters in a pulsed jet or a beam can be realized by using a fast ion gauge. Rapid positive feedback electron impact ionization and fragmentation processes,which are initially ignited by electron impact ionization of the krypton clusters with the electron current of the ion gauge, result in the appearance of a progressional oscillation-like ion spectrum, or just of a single fast event under critical conditions. Each line in the spectrum represents a correlated explosion or avalanche ionization of the clusters.The phenomena have been analysed qualitatively along with a Rayleigh scattering experiment of the corresponding cluster jet.

  14. Ionization applications in food industry - Generalities

    International Nuclear Information System (INIS)

    This paper outlines different applications of the ionization in food treatments and their purposes. Irradiation of food with low doses (below 1 kgy) is used for germination inhibition, insects sterilization, disinfestation and senescence delays. Applications with medium doses (from 1 to 10 kgy) are used for extension of shelf life, elimination of pathogenic microorganisms and improving technological properties. Applications with high doses (superior to 10 Kgy) are used for food sterilization, only in some specific cases. Necessary doses in various applications of food ionization are given as well as minimal doses for food sterilization. In some cases where treatment of food by only ionization do not permit to attain the fixed object, ionizing treatment is combined with an other type of treatment as: refrigeration, heat treatments, packing, dehydration and chemical treatments. 3 tabs., 5 refs. (F.M.)

  15. Multiple ionization of atoms by ion impact

    International Nuclear Information System (INIS)

    In order to model the energy deposition of fast ions as they slow down in gaseous media, information about the ionization occurring in collisions between ions and target atoms/molecules is required. Our measurements of doubly differential electron emission cross sections provide detailed information about the ionization process but do not provide any information about the final states of the target. They also do not distinguish between the emission of one or more target electrons in a single collision. It is important to know the relative importance of multiple-, with respect to single-, target ionization in order to accurately model the energy deposition. To date, multiple ionization of He, Ne, Ar, Kr, and Xe targets has been studied. Primarily, H and He ions were used, although some data for heavier ions (C,N and O) have also been obtained

  16. A correction to Birks' Law in liquid argon ionization chamber simulations for highly ionizing particles

    International Nuclear Information System (INIS)

    We present a study of the performance of Birks' Law in liquid argon ionization chamber simulations as applied to highly ionizing particles, such as particles with multiple electric charges or with magnetic charge. We used Birks' Law to model recombination effects in a GEANT4 simulation of heavy ions in a liquid argon calorimeter. We then compared the simulation to published heavy-ion data to extract a highly ionizing particle correction to Birks' Law.

  17. Ionization energy of acetone by vacuum ultraviolet mass-analyzed threshold ionization spectrometry

    International Nuclear Information System (INIS)

    Mass-analyzed threshold ionization (MATI) time-of-flight mass spectrometer using coherent vacuum ultraviolet (VUV) laser generated by four-wave difference frequency mixing (FWDFM) in Kr has been constructed and utilized to obtain the accurate ionization energy of acetone. From the MATI onsets measured from various applied pulsed fields, the ionization energy to the ionic ground state of acetone has been determined to be 9.7074 ± 0.0019 eV.

  18. 100 years of ionizing radiation protection

    International Nuclear Information System (INIS)

    The development of radiation protection from the end of 19. century and evolution of opinion about injurious effect of ionizing radiation were presented. Observations of undesirable effects of ionizing radiation exposition, progress of radiobiology and dosimetry directed efforts toward radiation protection. These activities covered, at the beginning, limited number of persons and were subsequently extended to whole population. The current means, goals and regulations of radiological control have been discussed

  19. Tomographic scanning apparatus with ionization detector means

    International Nuclear Information System (INIS)

    This patent specification describes a tomographic scanning apparatus using a fan beam and digital output signal. Particular reference is made to the gas-pressurized ionization detector chamber, consisting of an array of side-by-side elongate ionization detection cells, the principal axis of each of the said cells being oriented along a radius extending towards the radiation source, and connection means for applying potentials across the cells for taking their output signals. (U.K.)

  20. The warm ionized medium in spiral galaxies

    CERN Document Server

    Haffner, L M; Beckman, J E; Wood, K; Slavin, J D; Giammanco, C; Madsen, G J; Zurita, A; Reynolds, R J

    2009-01-01

    This article reviews observations and models of the diffuse ionized gas that permeates the disk and halo of our Galaxy and others. It was inspired by a series of invited talks presented during an afternoon scientific session of the 65th birthday celebration for Professor Carl Heiles held at Arecibo Observatory in August 2004. This review is in recognition of Carl's long standing interest in and advocacy for studies of the ionized as well as the neutral components of the interstellar medium.

  1. Positron impact ionization of atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G.O.; Charlton, M.; Slevin, J.; Laricchia, G.; Kover, A.; Poulsen, M.R.; Chormaic, S.N. (University Coll., London (United Kingdom). Dept. of Physics and Astronomy)

    1993-08-14

    Ionization cross sections for positrons impacting on atomic hydrogen have been measured for kinetic energies in the range 15-700 eV. This has been done in a crossed-beam geometry where a magnetically guided positron beam intersects a hydrogen gas jet emanating from a radio frequency discharge tube. Electron impact ionization cross sections were also measured with the same apparatus thus facilitating comparison with, and normalization to, published results. (author).

  2. Positron impact ionization of atomic hydrogen

    International Nuclear Information System (INIS)

    Ionization cross sections for positrons impacting on atomic hydrogen have been measured for kinetic energies in the range 15-700 eV. This has been done in a crossed-beam geometry where a magnetically guided positron beam intersects a hydrogen gas jet emanating from a radio frequency discharge tube. Electron impact ionization cross sections were also measured with the same apparatus thus facilitating comparison with, and normalization to, published results. (author)

  3. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  4. Conception of CTMSP ionizing radiation calibration laboratory

    International Nuclear Information System (INIS)

    The present paper describes the implantation process of an ionizing radiation calibration laboratory in a preexistent installation in CTMSP (bunker) approved by CNEN to operate with gamma-ray for non destructive testing. This laboratory will extend and improve the current metrological capacity for the attendance to the increasing demand for services of calibration of ionizing radiation measuring instruments. Statutory and regulatory requirements for the licensing of the installation are presented and deeply reviewed. (author)

  5. How periodic orbit bifurcations drive multiphoton ionization

    OpenAIRE

    Huang, S.; Chandre, C; Uzer, T.

    2006-01-01

    The multiphoton ionization of hydrogen by a strong bichromatic microwave field is a complex process prototypical for atomic control research. Periodic orbit analysis captures this complexity: Through the stability of periodic orbits we can match qualitatively the variation of experimental ionization rates with a control parameter, the relative phase between the two modes of the field. Moreover, an empirical formula reproduces quantum simulations to a high degree of accuracy. This quantitative...

  6. Theory of a critical ionization rate

    International Nuclear Information System (INIS)

    The mechanism for the anomalous ionization of a neutral gas by a plasma stream is analyzed. Electron heating due to a lower hybrid instability is analyzed in the theory of weak turbulence. A critical plasma velocity is required to sustain avalanche ionization. This critical velocity depends on the properties of the gas and of the plasma. In several cases it may exceed the value suggested previously by Alfven

  7. Effects of ionizing radiation on hippocampus

    International Nuclear Information System (INIS)

    The present situation in studying effects of ionizing radiation on hippocampus of brain was reviewed in these topics, such as the kinetics of hippocampus, influences of ionizing radiation, on neutrons, biochemistry, enzymes, transmitters and synapses in hippocampus and on its electrophysiology, and the neuro-behavior after irradiation of hippocampus of brain, in order to provide information for clarifying the mechanism is radiation effect on hippocampus and for protection of human

  8. Inner-shell ionization and stopping power

    International Nuclear Information System (INIS)

    For better understanding of various aspects in stopping phenomena such as Z13-dependence, shell correction, geometrical effect, direction dependence etc., it seems to be helpful to examine theoretically and experimentally the elementary processes which include plasmon excitation, single electron excitation and inner-shell excitation/ionization. In the present, impact-parameter dependent stopping power is discussed in connection with inner-shell ionization

  9. Fundamental studies of molecular multiphoton ionization

    International Nuclear Information System (INIS)

    For several years the authors have performed fundamental studies of molecular multiphoton ionization (MPI). We will present a potpourri of techniques and results chosen to illustrate the interesting complexities of molecular MPI. Techniques used include time-of-flight mass spectroscopy, photoelectron spectroscopy, supersonic expansion cooling of molecular beams, harmonic generation, two-color laser MPI, and polarization spectroscopy. Whenever possible the relevance of these results to resonance ionization spectroscopy schemes will be delineated. 23 references, 10 figures

  10. Advanced Magnetoimpedance Sensors

    KAUST Repository

    Li, Bodong

    2015-02-01

    This thesis is concerned with the advanced topics of thin film magnetoimpedance (MI) sensors. The author proposes and develops novel MI sensors that target on the challenges arising from emerging applications such as flexible electronics, passive wireless sensing, etc. In the study of flexible MI sensor, the investigated sensors of NiFe/Cu/NiFe tri-layersare fabricated on three flexible substrates having different surface roughness: Kapton, standard and premiumphotopaper. Sensitivity versus substrate roughness analysis is carried out for the selection of optimal substrate material. The high magnetic sensing performance is achieved by using Kapton substrate. Stress simulation, incorporated with the theory of magnetostriction effect, reveals the material composition of Ni/Fe being as a key factor of the stress dependent MI effect for the flexible MI sensors. In the development of MI-SAW device for passive wireless magnetic field sensing, NiFe/Cu/NiFe tri-layersand interdigital transducers(IDT) are designed and fabricated on a single piece of LiNbO3substrate, providing a high degree of integration and the advantage of standard microfabrication. The double-electrodeIDT has been utilized and proven to have an optimal sensing performance in comparison to the bi-directional IDT design. The optimized high frequency performance of the thin film MI sensor results in a MI-SAW passive wireless magnetic sensor with high magnetic sensitivity comparing to the MI microwire approach. Benefiting from the high degree of integration of the MI thin film element, in the following study, two additional sensing elements are integrated to the SAW device to have a multifunctional passive wireless sensor with extended temperature and humidity sensing capabilities. Analytical models havebeen developed to eliminate the crossovers of different sensing signals through additional reference IDTs, resulting in a multifunctional passive wireless sensor with the capability of detecting all three

  11. Two-photon ionization thresholds of matrix-assisted laser desorption/ionization matrix clusters.

    Science.gov (United States)

    Lin, Q; Knochenmuss, R

    2001-01-01

    Direct two-photon ionization of the matrix has been considered a likely primary ionization mechanism in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. This mechanism requires that the vertical ionization threshold of matrix materials be below twice the laser photon energy. Because dimers and larger aggregates may be numerous in the early stages of the MALDI plume expansion, their ionization thresholds are important as well. We have used two-color two-photon ionization to determine the ionization thresholds of jet cooled clusters of an important matrix, 2,5-dihydroxy benzoic acid (DHB), and mixed clusters with the thermal decomposition product of DHB, hydroquinone. The thresholds of the clusters were reduced by only a few tenths of an eV compared to the monomers, to an apparent limit of 7.82 eV for pure DHB clusters. None of the investigated clusters can be directly ionized by two nitrogen laser photons (7.36 eV), and the ionization efficiency at the thresholds is low. PMID:11507754

  12. Commercial applications of food ionization in France

    International Nuclear Information System (INIS)

    Due to the long history of nuclear energy in France, French public is not frightened by nuclear applications in its everyday life. The first industrial initiative on food ionization dates back to 1956. In 1980, the Joint Expert Committee on Food Ionization concluded that food ionization up to a certain maximum dose presented neither toxicological nor nutritional hazard. This opened the new era for the industrial development. But in 1988, a draft directive to harmonize national legislations was issued by the Commission of European Communities. This stopped many industrial initiatives due to uncertainty. It is estimated that nearly 14,000 tons of various food items have been ionized in France in 1991. About 40% are spices, followed by dry fruit, vegetables, and deboned poultry meat. Most of the present applications are intended to eliminate microorganisms. In 1992, 8 industrial facilities were in operation, mostly using gamma sources. Local research associations were founded to promote food ionization. Food ionization development in the past 30 years has been rapid and important, but the future of this process depends on the European harmonization of legislations. (K.I.)

  13. New standards for ionizing radiation measurements

    International Nuclear Information System (INIS)

    The Ionizing Radiation Division has developed new national standards for mammographic X rays and for brachytherapy sources, such as iodine-125. The Attix chamber, a variable volume free-air ionization chamber, has been established as the primary national standard for mammographic X rays. The Attix chamber resides in the newly developed NIST Mammography Calibration Range and will be used to perform routine calibrations. The wide-angle free-air ionization chamber utilizes a large volume and a novel electric field configuration in order to circumvent the limitations of conventional free-air chambers. Seventeen beam qualities for X rays from molybdenum (Mo) and rhodium (Rh) anodes have been parameterized for the calibration of mammographic ionization chambers. The beam qualities available include anode/filter combinations of Mo/Mo, Mo/Rh and Rh/Rh. The mammography range was developed in collaborations with the U.S. Food and Drug Administration's (FDA) Center for Devices and Radiological Health, the implementors of the Mammography Quality Standards Act (MQSA) of 1992. The wide-angle free-air ionization chamber has been used to measure the output of two types of iodine-125 seeds, those with resin balls and those with silver wire. Both free-air chambers have been intercompared with the Ritz parallel-plate free-air ionization chamber

  14. Comparison among different CT ionization chambers

    International Nuclear Information System (INIS)

    The dosimetry in computed tomography (CT) is carried out by the use of a pencil type ionization-chamber, because it has a uniform response at all angles relative to the incident beam of radiation, which is essential for CT equipment since the X-ray tube executes a circular movement around the table during irradiation. The commercial ionization chamber used to perform quality control procedures of this kind of equipment has a length of the sensitive volume of 10 cm. In the Calibration Laboratory of Instruments (LCI) of the IPEN there were already developed some prototypes with small differences in construction, when compared to commercially available ionization chambers. They have been used in previous studies and showed results within internationally acceptable limits. The ionization chambers tested in this study present the sensitive volume lengths of 1 cm, 3 cm and 10 cm. The objective of this study was to present results on the stability test of the three homemade ionization chambers and a commercial chamber, as well to obtain the calibration coefficients for each of them in CT standard X radiation beams. The obtained results for both characterization tests are within the recommended limits, except for the homemade ionization chambers with sensitive volume lengths of 3 cm and 1 cm in the case of the stability test. (author)

  15. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  16. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The...

  17. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  18. Nanostructured silicon surface modifications for as a selective matrix-free laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Tsao, C W; Lin, C H; Cheng, Y C; Chien, C C; Chang, C C; Chen, W Y

    2012-06-01

    Matrix-assisted laser desorption/ionization mass spectrometry is an established soft ionization method that is widely applied to analyze biomolecules. The UV-absorbing organic matrix is essential for biomolecule ionization; however, it also creates matrix background interference, which results in problematic analyses of biomolecules of less than 700 Da. Therefore, this study investigates hydrophilic, hydrophobic cationic, anionic and immobilized metal ion surface chemical modifications to advance nanostructured silicon mass spectrometry performance (nSi-MS). This investigation provides information required for a possible novel mass spectroscopy that combines surface-enhanced and nanostructured silicon surface-assisted laser desorption/ionization mass spectrometry for the selective detection of specific compounds of a mixture. PMID:22531330

  19. DC field response of one-dimensional flames using an ionized layer model

    KAUST Repository

    Xiong, Yuan

    2015-11-18

    We develop a simplified model to better explain electric current response when direct current (DC) is applied to a flame. In particular, different current responses have been observed by changing the polarity of the DC in a sub-saturated current regime that results from the presence of ions and electrons in the flame zone. A flame zone was modeled as a thin, ionized layer located in one-dimensional DC electric fields. We derived simplified model-governing equations from species equations by implementing mobility differences dependent on the type of charged particle, particularly between ions and electrons; we performed experiments to substantiate the model. Results showed that the sub-saturated current and local field intensity were significantly influenced by the polarity of the DC because of the combined effect of unequal mobility of charged particles and the position of the ionized layer in the gap relative to two electrodes. When an energized electrode is close to the ionized layer, applying a negative DC causes a more rapid increase in current than by applying a positive DC to the same electrode. Results from our experimental measurement of current using counterflow diffusion flames agreed qualitatively well with the model predictions. A sensitivity analysis using dimensional and non-dimensional parameters also supported the importance of the mobility difference and the relative location of the ionized layer on the electric current response.

  20. Current saturation in free-air ionization chambers with chopped synchrotron radiation

    International Nuclear Information System (INIS)

    An expression for ion recombination in free-air ionization chambers irradiated by chopped X-rays is presented. The expression is validated by comparison with experiments using synchrotron radiation. Saturation curves for free-air ionization chambers with electrode gap widths of 4.2, 8.4 and 18 mm were obtained for 10 and 15 keV undulator synchrotron radiation thinned with a 230 Hz rotating-disk chopper. Ion recombination in free-air ionization chambers was found to be inversely proportional to the applied electric field, and an expression that satisfactorily reproduced the ion-recombination rate is determined. A comparison of the expressions for continuous and pulsed X-rays revealed that chopped high-intensity X-rays require a higher voltage to attain saturation when the product of the pulse width and electric field exceeds a value that depends on the X-ray energy. This behaviour was observed explicitly for 10 keV X-rays in measurements with the ionization chamber placed before and after the chopper

  1. Statistical approach to multiphoton multielectron ionization of atoms

    International Nuclear Information System (INIS)

    State density and temperature of excited atom were found. Diffusion equation with sink was suggested for describing ionization process. It was shown that possibility of multielectron ionization was dictated by the competition of atom heating by external field and evaporation ionization. Numerical calculation of xenon atom ionization was conducted and correlation with experimental results was given

  2. Materials characterization using ion bombardment and multiphoton resonance ionization

    International Nuclear Information System (INIS)

    The combination of energetic ion bombardment with multiphoton resonance ionization (MPRI) spectroscopy has proven to be an important advancement in surface science. The goal of this project is continuing the development of MPRI of desorbed neutrals as a surface analytical tool. The method for accomplishing this is a detailed examination of the factors which govern a measurement and the implementation of the optimum experimental approach. Initially, a review of the progress in laser post-ionization of desorbed neutral particles is presented. This is followed by a description of the newly redesigned instrument, emphasizing detailed characterization of the high current ion source and the reflecting time-of-flight mass spectrometer. Using the new apparatus, the quantitative aspects of the measurement are examined and the fractions of desorbed ions and neutrals are determined using several matrices. The In concentration in a set of silicon wafers is measured, yielding a detection limit of 9 parts-per-trillion. Finally, the prospects for employing this experiment for measuring the half-life of the rare double beta decay of 136Xe to 136Ba are assessed

  3. Desulfurization of petroleum induced by ionization radiation: benzothiophene behavior

    International Nuclear Information System (INIS)

    Hydrodesulfurization (HDS) is currently the most common method used by refineries; this removes significantly sulfur compounds from petroleum fractions, however, is not highly effective for removing thiophene compounds such as benzothiophene, and generates high costs for the oil industry. Another factor, are the environmental laws, which over the years has become increasingly strict, especially regarding the sulfur content. This compound cause incalculable damage both to the industry and to the environment. Therefore new methods for petroleum desulfurization should be studied in order to minimize the impacts that these compounds cause. In the present study it was used ionizing radiation, a promising method of advanced oxidation in reducing sulfur compounds. The analysis were performed after purge and trap concentration of samples, followed by gas chromatography-mass spectrometry (GC-MS). Then benzothiophene samples with the same concentration from 27 mg.L-1 to 139 mg.L-1 were irradiated with different absorbed doses of radiation ranging from 1 kGy to 20 kGy in gamma irradiator Cobalt-60, Gammacell. These samples were analyzed by the same procedure used for the calibration curve, and the removals of benzothiophene after ionizing radiation treatment were calculated. It was observed that at higher doses there was a greater degradation of this compound and the formation of fragments, such as 1,2-dimethylbenzene and toluene, which may be removed by simple processes. (author)

  4. Advanced calculus

    CERN Document Server

    Nickerson, HK; Steenrod, NE

    2011-01-01

    ""This book is a radical departure from all previous concepts of advanced calculus,"" declared the Bulletin of the American Mathematics Society, ""and the nature of this departure merits serious study of the book by everyone interested in undergraduate education in mathematics."" Classroom-tested in a Princeton University honors course, it offers students a unified introduction to advanced calculus. Starting with an abstract treatment of vector spaces and linear transforms, the authors introduce a single basic derivative in an invariant form. All other derivatives - gradient, divergent, curl,

  5. Evidence for DCO+ as a probe of ionization in the warm disk surface

    CERN Document Server

    Favre, Cécile; Cleeves, L Ilsedore; Hersant, Franck; Qi, Chunhua; Aikawa, Yuri

    2015-01-01

    In this Letter we model the chemistry of DCO$^{+}$ in protoplanetary disks. We find that the overall distribution of the DCO$^{+}$ abundance is qualitatively similar to that of CO but is dominated by thin layer located at the inner disk surface. To understand its distribution, we investigate the different key gas-phase deuteration pathways that can lead to the formation of DCO$^{+}$. Our analysis shows that the recent update in the exothermicity of the reaction involving CH$_2$D$^{+}$ as a parent molecule of DCO$^{+}$ favors deuterium fractionation in warmer conditions. As a result the formation of DCO$^{+}$ is enhanced in the inner warm surface layers of the disk where X-ray ionization occurs. Our analysis points out that DCO$^{+}$ is not a reliable tracer of the CO snow line as previously suggested. We thus predict that DCO$^{+}$ is a tracer of active deuterium and in particular X-ray ionization of the inner disk.

  6. Shotgun Approach for Quantitative Imaging of Phospholipids Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lanekoff, Ingela T.; Thomas, Mathew; Laskin, Julia

    2014-02-04

    Mass spectrometry imaging (MSI) has been extensively used for determining spatial distributions of molecules in biological samples, and there is increasing interest in using MSI for quantification. Nanospray desorption electrospray ionization, or nano-DESI, is an ambient MSI technique where a solvent is used for localized extraction of molecules followed by nanoelectrospray ionization. Doping the nano-DESI solvent with carefully selected standards enables online quantification during MSI experiments. In this proof-of-principle study, we demonstrate this quantification approach can be extended to provide shotgun-like quantification of phospholipids in thin brain tissue sections. Specifically, two phosphatidylcholine (PC) standards were added to the nano-DESI solvent for simultaneous imaging and quantification of 22 PC species observed in nano-DESI MSI. Furthermore, by combining the quantitative data obtained in the individual pixels, we demonstrate quantification of these PC species in seven different regions of a rat brain tissue section.

  7. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    International Nuclear Information System (INIS)

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10–7) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10–6-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H2, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks

  8. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Stark, C. R.; Helling, Ch.; Rimmer, P. B. [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS (United Kingdom); Diver, D. A., E-mail: craig.stark@st-andrews.ac.uk [SUPA, School of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

    2013-10-10

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10{sup –7}) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10{sup –6}-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H{sub 2}, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  9. A grid-ionization chamber and a ΔE-E particle telescope detection set-up

    International Nuclear Information System (INIS)

    A detection set-up, composed of a typical grid-ionization chamber and a ΔE-E particle telescope, was constructed to study the charge distributions of fragments in spontaneous fission of 252Cf. The fission fragment energy and the emission angle corresponding to the symmetrical axis were measured by the grid-ionization chamber, the ΔE-E particle telescope in which a thin grid-ionization chamber was served as the ΔE-section and a surface barrier detector as the E-section was employed to determined the charge of the complementary fragment. Four parameter measurements of 252Cf spontaneous fission were performed by this set-up, the results show that the charge resolution of Z/ΔZ>40:1 can be obtained by this detector system. (authors)

  10. Detailed Investigations of Interactions between Ionizing Radiation and Neutral Gases

    Energy Technology Data Exchange (ETDEWEB)

    Landers, Allen L

    2014-03-31

    We are investigating phenomena that stem from the many body dynamics associated with ionization of an atom or molecule by photon or charged particle. Our program is funded through the Department of Energy EPSCoR Laboratory Partnership Award in collaboration with Lawrence Berkeley National Laboratory. We are using variations on the well established COLTRIMS technique to measure ions and electrons ejected during these interactions. Photoionization measurements take place at the Advanced Light Source at LBNL as part of the ALS-COLTRIMS collaboration with the groups of Reinhard Dörner at Frankfurt and Ali Belkacem at LBNL. Additional experiments on charged particle impact are conducted locally at Auburn University where we are studying the dissociative molecular dynamics following interactions with either ions or electrons over a velocity range of 1 to 12 atomic units.

  11. Application of Solid Phase Microextraction followed by Chromatograph-Flame Ionization Detector for Sampling and Analysis of Acetonitrile in Air

    OpenAIRE

    NEMATULLAH KURD; ABDULRAHMAN BAHRAMI; FARSHID GHORBANI-SHAHNA; MAHMOUD HEIDARI

    2015-01-01

    Acetonitrile used as a solvent in manufactures and affects to central nervous system from inhalation exposure. The aim of this study was to develop a micro-solid phase extraction method for the determination of acetonitrile in the air matrix. The sampling was performed with a small diameter fused silica fiber coated with a thin film of stationary phase and was subsequently desorbed and analyzed by gas chromatograph equipped with a flame ionization detector (GC/FID). The effects of laboratory ...

  12. 2.3.2 Biological Effects of Non-Ionizing Radiations

    Science.gov (United States)

    Bernhardt, J. H.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.3.2 Biological Effects of Non-Ionizing Radiations' of the Section '2.3 Biological Effects' of the Chapter '2 Radiation and Biological Effects' with the contents:

  13. Vibrational Distribution of Hydrogen Molecular Ions in High-Energy Ionization Processes

    Institute of Scientific and Technical Information of China (English)

    CHEN Shao-Hao; HE Chun-Long; CHEN Chao; LI Jia-Ming

    2005-01-01

    @@ A theoretical time-dependent wave-packet dynamics method is applied to calculate the distribution of vibrational states of hydrogen molecular ions produced in high-energy ionization processes of hydrogen molecules. The isotope effect is elucidated in agreement with the available experimental measurements. Our proposed method should be readily applied in other atomic and molecular processes considering great advances in electronic computation science and technology.

  14. Advanced ferroelectricity

    CERN Document Server

    Blinc, R

    2011-01-01

    Advances in the field of ferroelectricity have implications both for basic physics and for technological applications such as memory devices, spintronic applications and electro-optic devices, as well as in acoustics, robotics, telecommunications and medicine. This book provides an account of recent developments in the field.

  15. US Polycrystalline Thin Film Solar Cells Program

    Science.gov (United States)

    Ullal, Harin S.; Zweibel, Kenneth; Mitchell, Richard L.

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R and D on copper indium diselenide and cadmium telluride thin films. The objective of the program is to support research to develop cells and modules that meet the U.S. Department of Energy's long-term goals by achieving high efficiencies (15 to 20 percent), low-cost ($50/m(sup 2)), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe2 and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The U.S. Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe2 and CdTe with subcontracts to start in spring 1990.

  16. US polycrystalline thin film solar cells program

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H S; Zweibel, K; Mitchell, R L [Solar Energy Research Inst., Golden, CO (USA)

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R D on copper indium diselenide and cadmium telluride thin films. The objective of the Program is to support research to develop cells and modules that meet the US Department of Energy's long-term goals by achieving high efficiencies (15%-20%), low-cost ($50/m{sup 2}), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The US Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe{sub 2} and CdTe with subcontracts to start in Spring 1990. 23 refs., 5 figs.

  17. A search for ionized jets towards massive young stellar objects

    Science.gov (United States)

    Purser, S. J. D.; Lumsden, S. L.; Hoare, M. G.; Urquhart, J. S.; Cunningham, N.; Purcell, C. R.; Brooks, K. J.; Garay, G.; Gúzman, A. E.; Voronkov, M. A.

    2016-07-01

    Radio continuum observations using the Australia telescope compact array at 5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45 of 49 massive young stellar objects and H II regions. Of these, 26 sources are classified as ionized jets (12 of which are candidates), 2 as ambiguous jets or disc winds, 1 as a disc-wind, 14 as H II regions and 2 were unable to be categorized. Classification as ionized jets is based upon morphology, radio flux and spectral index, in conjunction with previous observational results at other wavelengths. Radio luminosity and momentum are found to scale with bolometric luminosity in the same way as low-mass jets, indicating a common mechanism for jet production across all masses. In 13 of the jets, we see associated non-thermal/optically thin lobes resulting from shocks either internal to the jet and/or at working surfaces. 10 jets display non-thermal (synchrotron emission) spectra in their lobes, with an average spectral index of α = -0.55 consistent with Fermi acceleration in shocks. This shows that magnetic fields are present, in agreement with models of jet formation incorporating magnetic fields. Since the production of collimated radio jets is associated with accretion processes, the results presented in this paper support the picture of disc-mediated accretion for the formation of massive stars with an upper limit on the jet phase lasting approximately 6.5 × 104 yr. Typical mass-loss rates in the jet are found to be 1.4 × 10-5 M⊙ yr-1 with associated momentum rates of the order of (1-2) × 10-2 M⊙ km s-1 yr-1.

  18. A search for ionized jets towards massive young stellar objects

    Science.gov (United States)

    Purser, S. J. D.; Lumsden, S. L.; Hoare, M. G.; Urquhart, J. S.; Cunningham, N.; Purcell, C. R.; Brooks, K. J.; Garay, G.; Gúzman, A. E.; Voronkov, M. A.

    2016-05-01

    Radio continuum observations using the Australia telescope compact array at 5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45 of 49 massive young stellar objects and HII regions. Of these, 26 sources are classified as ionized jets (12 of which are candidates), 2 as ambiguous jets or disc winds, 1 as a disc-wind, 14 as HII regions and 2 were unable to be categorised. Classification as ionized jets is based upon morphology, radio flux and spectral index, in conjunction with previous observational results at other wavelengths. Radio-luminosity and momentum are found to scale with bolometric luminosity in the same way as low-mass jets, indicating a common mechanism for jet production across all masses. In 13 of the jets, we see associated non-thermal/optically-thin lobes resulting from shocks either internal to the jet and/or at working surfaces. Ten jets display non-thermal (synchrotron emission) spectra in their lobes, with an average spectral index of α = -0.55 consistent with Fermi acceleration in shocks. This shows that magnetic fields are present, in agreement with models of jet formation incorporating magnetic fields. Since the production of collimated radio jets is associated with accretion processes, the results presented in this paper support the picture of disc-mediated accretion for the formation of massive stars with an upper-limit on the jet phase lasting approximately 6.5 × 104 yr. Typical mass loss rates in the jet are found to be 1.4× 10-5 M⊙yr-1 with associated momentum rates of the order (1-2)× 10^{-2} M_⊙ km s^{-1 yr}^{-1}.

  19. Actual trends in chip electrospray ionization mass spectrometry

    International Nuclear Information System (INIS)

    Full text: Mass spectrometry (MS) has the potential to revolutionize carbohydrate research and help in understanding of how post-translational events such as glycosylation affect biomolecular activities. In the past decade, capillary nanoelectrospray (nanoESI) MS developed as an effective means in glycomics. However, the disadvantages of the method include low sample throughput, potential sample carryover, and poor reproducibility due to the variable shape of the spray tip. The recent introduction of chip-based nano and microESI in biological MS is driven by the high performance, efficiency, throughput, sensitivity and speed of analysis. The analytical potential of these assemblies were lately largely proven in proteomics, direct bioanalyses of drugs, drug development and small molecule characterization. For the MS ionization/separation of quantity-limited complex carbohydrates derived from biological matrices, our group implemented in the last few years an arsenal of novel methodologies based on microfluidics and lab-on-a-chip systems. In this study microfluidic ESI systems operating in the negative ion mode, in combination with Fourier transform ion cyclotron resonance (FTICR) at 9.4 Tesla and quadrupole time-of-flight (QTOF) tandem mass spectrometry (MS/MS) are introduced for glycolipidomic surveys in biomedical research. Two different chip ESI systems: a fully automated chip-based nanoESI robot and a thin chip microsprayer have been coupled each to both a hybrid quadrupole time-of-flight (QTOF) MS and a Fourier transform ion cyclotron resonance (FTICR) MS at 9.4 T. The feasibility of the chip MS approaches was tested for the determination of ganglioside differential expression in human brain regions and elucidation of the topospecific structures. The obtained data indicate that the high sensitivity and ionization efficiency provided at nano- and microscale level by the chip MS infusion in combination with tandem MS make this new approach ideal for studies

  20. Usage of Thin-Client/Server Architecture in Computer Aided Education

    Science.gov (United States)

    Cimen, Caghan; Kavurucu, Yusuf; Aydin, Halit

    2014-01-01

    With the advances of technology, thin-client/server architecture has become popular in multi-user/single network environments. Thin-client is a user terminal in which the user can login to a domain and run programs by connecting to a remote server. Recent developments in network and hardware technologies (cloud computing, virtualization, etc.)…

  1. Performance of mechanical thinners for bloom or green fruit thinning in peaches

    Science.gov (United States)

    Removal of excess fruits (thinning) is one of the most time consuming and costly operations in a peach orchard. A mechanical aid to assist in peach thinning would be a significant advancement for peach growers. A cooperative study between Penn State University and the USDA-ARS, Appalachian Fruit R...

  2. Conceptual basis of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Resonance Ionization Spectroscopy (RIS) can b defined as a state-selective detection process in which tunable lasers are used to promote transitions from the selected state of the atoms or molecules in question to higher states, one of which will be ionized by the absorption of another photon. At least one resonance step is used in the stepwise ionization process, and it has been shown that the ionization probability of the spectroscopically selected species can nearly always be made close to unity. Since measurements of the number of photoelectrons or ions can be made very precisely and even one electron (or under vacuum conditions, one ion) can be detected, the technique can be used to make quantitative measurements of very small populations of the state-selected species. Counting of individual atoms has special meaning for detection of rare events. The ability to make saturated RIS measurements opens up a wide variety of applications to both basic and applied research. We view RIS as a specific type of multi-photon ionization in which the goal is to make quantitative measurements of quantum-selected populations in atomic or molecular systems. 16 references

  3. The primordial abundance of deuterium: ionization correction

    Science.gov (United States)

    Cooke, Ryan; Pettini, Max

    2016-01-01

    We determine the relative ionization of deuterium and hydrogen in low metallicity damped Lyman α (DLA) and sub-DLA systems using a detailed suite of photoionization simulations. We model metal-poor DLAs as clouds of gas in pressure equilibrium with a host dark matter halo, exposed to the Haardt & Madau background radiation of galaxies and quasars at redshift z ≃ 3. Our results indicate that the deuterium ionization correction correlates with the H I column density and the ratio of successive ion stages of the most commonly observed metals. The N(N II)/N(N I) column density ratio provides the most reliable correction factor, being essentially independent of the gas geometry, H I column density, and the radiation field. We provide a series of convenient fitting formulae to calculate the deuterium ionization correction based on observable quantities. The ionization correction typically does not exceed 0.1 per cent for metal-poor DLAs, which is comfortably below the current measurement precision (2 per cent). However, the deuterium ionization correction may need to be applied when a larger sample of D/H measurements becomes available.

  4. LET measurements with a liquid ionization chamber

    International Nuclear Information System (INIS)

    Deep-seated tumors can be efficiently treated with heavy charged particles. The characteristic depth dose profile inside the tissue (Bragg peak) allows to deliver a high dose inside the tumor, while sparing the neighboring healthy tissue. As compared to protons, heavy ions like carbon or oxygen produce a higher amount of ionization events along their track (and in particular at the end of the ion beam path), resulting in an irreparable damage to the DNA of the tumor cells. The density of such ionization events is described in terms of Linear Energy Transfer (LET), an important physical quantity, but difficult to be measured directly. The aim of this work is to determine LET of hadrontherapy beams by using Liquid Ionization Chambers (LIC). The ionization signal in LICs is affected by recombination effects that depend on the LET of the incident radiation. Differences in recombination effects in LICs and air-filled ionization chambers can be exploited to obtain the recombination index, which can be related to the LET, calculated by Monte Carlo methods. We thus developed a method to construct a calibration curve, which relates the recombination index with the LET at each depth in water. The result of this work can be used for online monitoring of the ion beam quality.

  5. Pressurized ionization chamber detectors for industrial use

    International Nuclear Information System (INIS)

    The measurement of the thickness of the sheets made of different materials, e.g. metal, plastic, paper, cellulose, rubber, etc., is one of many industrial applications of nuclear techniques. The ionizing radiation detectors of ionization chamber type are based on measuring the variations in either exposure rate (for gamma radiation) or absorbed dose rate (for beta radiation) occurring in materials of different thickness, placed between the radiation source and the detector. The variations in exposure rate and absorbed dose rate can be traced by using radiation detectors of the ionization chamber type, which convert the exposure rate, X point, or the absorbed dose rate, D point, into a proportional electric current. The more stable the ionization current of the chambers (keeping a constant exposure rate or absorbed dose rate), the slighter the variations that can be detected in either exposure rate or absorbed dose rate, hence in the absorbing material placed between the radiation source and the detector. Based on these facts, several variants of such detectors, including the ionization chamber CIS-P5M-100Kr, CIS-P2M-1000Kr and CIS-P8M-70Kr, have been made. (author)

  6. Multiphoton ionization of large water clusters

    International Nuclear Information System (INIS)

    Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure

  7. Laboratory simulation of cometary neutral gas ionization

    International Nuclear Information System (INIS)

    The laboratory simulation of the interaction of the solar wind with a comet is used to study the cometary neutral gas ionization. The experiment is carried out in the UCR T-1 facility with an ice ball as the comet model. Photographs and data are taken with a variety of values of the solar wind velocity, interplanetary magnetic field (IMF), and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above certain minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. The critical magnetic field may be explained by assuming two stream lower hybrid instability as a triggering mechanism for the ionization of the neutral gas by plasma flow. Critical upper and lower limits for the magnetic field, required by anomalous ionization, are also derived that satisfy the experimental observations

  8. Laboratory simulation of cometary neutral gas ionization

    Science.gov (United States)

    Chang, Tsuey-Fen; Rahman, H. U.; White, R. S.

    1989-01-01

    The laboratory simulation of the interaction of the solar wind with a comet is used to study the cometary neural gas ionization. The experiment is carried out in the UCR T-1 facility with an ice ball as the comet model. Photographs and data are taken with a variety of values of the solar wind velocity, interplanetary magnetic field (IMF), and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above certain minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. The critical magnetic field may be explained by assuming two stream lower hybrid instability as a triggering mechanism for the ionization of the neutral gas by plasma flow. Critical upper and lower limits for the magnetic field, required by anomalous ionization, are also derived that satisfy the experimental observations.

  9. Generation of slow muon beam by laser resonant ionization of muonium atoms

    International Nuclear Information System (INIS)

    We report first results of re-acceleration of thermal muons, which were generated by laser resonant ionization of muonium atoms. The re-accelerated beam (slow muon beam) has better energy resolution and space distribution compared to initial surface muon beam, and its use will extend the scope of muon spin relaxation technique from bulk material to thin film, multi-layers, surfaces and extremely small samples. The yield of slow muons obtained during the first beam time was 0.03 muons/s

  10. Convoy electron emission following ionization of highly-charged ions excited by resonant coherent excitation

    Science.gov (United States)

    Suda, S.; Nakano, Y.; Metoki, K.; Shindo, T.; Ohtsuki, S.; Azuma, T.; Hatakeyama, A.; Komaki, K.; Nakai, Y.; Takada, E.; Murakami, T.

    2012-11-01

    Projectile ionization of highly-charged Ar and Fe ions in the excited states passing relativistically fast through a thin crystalline foil was experimentally studied. We selectively controlled the population of the excited states of the projectiles, and their alignment by choosing a specific m-state through three-dimensional resonant coherent excitation technique by periodical electric fields in a crystalline. We measured energy-differential spectra of electron emission released from projectiles at zero degree. Under the resonance condition, we found an evident enhancement of the convoy electron yield, which reflects the electron momentum distribution of the initial bound state of the excited ions.

  11. Ionization of covalent immobilized poly(4-vinylphenol) monolayers measured by ellipsometry, QCM and SPR

    Energy Technology Data Exchange (ETDEWEB)

    Uppalapati, Suji [Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., Lowell, MA 01854 (United States); Kong, Na; Norberg, Oscar [KTH-Royal Institute of Technology, Department of Chemistry, Teknikringen 30, S-10044 Stockholm (Sweden); Ramström, Olof, E-mail: ramstrom@kth.se [KTH-Royal Institute of Technology, Department of Chemistry, Teknikringen 30, S-10044 Stockholm (Sweden); Yan, Mingdi, E-mail: Mingdi_Yan@uml.edu [Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., Lowell, MA 01854 (United States); KTH-Royal Institute of Technology, Department of Chemistry, Teknikringen 30, S-10044 Stockholm (Sweden)

    2015-07-15

    Covalently immobilized poly(4-vinylphenol) (PVP) monolayer films were fabricated by spin coating PVP on perfluorophenyl azide (PFPA)-functionalized surfaces followed by UV irradiation. The pH-responsive behavior of these PVP ultrathin films was evaluated by ellipsometry, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). By monitoring the responses of these films to pH in situ, the ionization constant of the monolayer thin films was obtained. The apparent pK{sub a} value of these covalently immobilized PVP monolayers, 13.4 by SPR, was 3 units higher than that of the free polymer in aqueous solution.

  12. Alfvén's critical ionization velocity observed in high power impulse magnetron sputtering discharges

    International Nuclear Information System (INIS)

    Azimuthally rotating dense plasma structures, spokes, have recently been detected in several high power impulse magnetron sputtering (HiPIMS) devices used for thin film deposition and surface treatment, and are thought to be important for plasma buildup, energizing of electrons, as well as cross-B transport of charged particles. In this work, the drift velocities of these spokes are shown to be strongly correlated with the critical ionization velocity, CIV, proposed by Alfvén. It is proposed as the most promising approach in combining the CIV and HiPIMS research fields is to focus on the role of spokes in the process of electron energization.

  13. Ionization of covalent immobilized poly(4-vinylphenol) monolayers measured by ellipsometry, QCM and SPR

    International Nuclear Information System (INIS)

    Covalently immobilized poly(4-vinylphenol) (PVP) monolayer films were fabricated by spin coating PVP on perfluorophenyl azide (PFPA)-functionalized surfaces followed by UV irradiation. The pH-responsive behavior of these PVP ultrathin films was evaluated by ellipsometry, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). By monitoring the responses of these films to pH in situ, the ionization constant of the monolayer thin films was obtained. The apparent pKa value of these covalently immobilized PVP monolayers, 13.4 by SPR, was 3 units higher than that of the free polymer in aqueous solution

  14. Systematic study of L-shell ionization of some rare earth elements by light ion bombardment

    International Nuclear Information System (INIS)

    Thin targets of La, Pr, Nd, Eu, Tb, Ho and Er were bombarded by 1H, 2H, 3H, 4He and 7Li projectiles. The production cross sections for the Lα1,2, Lβ1,3,4, Lβ2,5,7, Lγ1,5, Lγ2,3,6 and Ll transitions have been extracted and corresponding ionization cross sections for L1-, L2- and L3- subshells have been calculated and tabulated. 9 figs., 13 tabs., 37 refs. (author)

  15. Inner-shell vacancy production and multiple ionization effects in 0.1-1.75 MeV/u Mn, Fe, Co, Ni, Cu + Au, Bi collisions

    International Nuclear Information System (INIS)

    Vacancy production in 0.1-1.75 MeV/u Mn, Fe, Co, Ni, Cu + Au, Bi collisions has been studied by measuring integral inner-shell ionization cross-sections and mean outer-shell ionization probabilities at the Tandem accelerator of NIPNE, Bucharest. X-ray spectra induced by ion beams of Mn, Fe, Co, Ni and Cu impinging on thin solid-foil targets of Au and Bi have been measured. Total ionization cross-sections for the K-shell of the projectile and L3-subshell of the target, as well as vacancy sharing probabilities, corrected for the effect of multiple ionization, are reported. The experimental results are discussed in terms of two model calculations

  16. Spectroscopic study of thorium using continuous-wave resonance ionization mass spectrometry with ultraviolet ionization

    International Nuclear Information System (INIS)

    This paper presents recent results on an improved method of ionization for the cw-RIMS process for thorium (Th). This method involves the application of a high power ultraviolet (UV) argon ion laser for the second step in a two-step (1 + 1) (photon-to-resonance plus photon-to-ionization) ionization scheme. Over 90 thorium transitions are identified for use in a (1 + 1) continuous-wave resonance ionization mass spectrometry (cw-RIMS) ionization scheme. The excitation cross-section of several strong transitions was determined to be 10-13cm2. The optimum cw excitation scheme was with the resonant laser tuned to the 384.08 nm (26 036 cm-1 transition when when using the multi-line UV argon ion laser for signal enhancement. For thorium, the increase in ionization efficiency was documented to be a minimum of one order-of-magnitude improvement that achieved by conventional thermal ionization mass spectrometry (TIMS). The measured total ionization efficiency (detected ion signal/sample atoms loaded) was as high as 0.41%, which easily provided signals levels for efficiency measurements on sample sizes down to 25 ng, and should provide sufficient signal for isotopic analysis of volcanic-like samples as small as 1-5 ng of thorium. Based on geometric overlap considerations, the cw-RIMS ionization efficiency within the laser focal volume approaches ∼ 100%. This cw-RIMS ionization efficiency promises to provide ample signal for the 230Th/232Th isotope ratio analysis of nanogram volcanic-like samples. The ability to determine accurately and precisely the 230Th/232Th isotopic ratios for nanogram samples represents an improvement over the TIMS technique, and is anticipated to have a significant effect on uranium-series disequilibrium measurements important in geochemistry and geochronology. (Author)

  17. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    The normal component of thin-film thermal conductivity has been measured for the first time, to the best of our knowledge, for several advanced sputtered optical materials. Included are data for single layers of boron nitride, silicon aluminum nitride, silicon aluminum oxynitride, silicon carbide, and for dielectric-enhanced metal reflectors of the form Al(SiO2/Si3N4)n and Al(Al2O3/AlN)n. Sputtered films of more conventional materials such as SiO2, Al2O3, Ta2O5, Ti, and Si have also been measured. The data show that thin-film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film--substrate interface contribution is presented

  18. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    International Nuclear Information System (INIS)

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  19. Advanced Virgo

    CERN Multimedia

    Virgo, a first-generation interferometric gravitational wave (GW) detector, located in the European Gravitational Observatory, EGO, Cascina (Pisa-Italy) and constructed by the collaboration of French and Italian institutes (CNRS and INFN) has successfully completed its long-duration data taking runs. It is now undergoing a fundamental upgrade that exploits available cutting edges technology to open an exciting new window on the universe, with the first detection of a gravitational wave signal. Advanced Virgo (AdV) is the project to upgrade the Virgo detector to a second-generation instrument. AdV will be able to scan a volume of the Universe 1000 times larger than initial Virgo. AdV will be hosted in the same infrastructures as Virgo. The Advanced VIRGO project is funded and at present carried on by a larger collaboration of institutes belonging to CNRS- France , RMKI - Hungary, INFN- Italy, Nikhef - The Netherlands Polish Academy of Science - Poland.

  20. Thin film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  1. Thin film temperature sensor

    Science.gov (United States)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  2. Weak interaction studies using resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Important developments in laser sources for the vacuum ultraviolet (VUV) region of the spectrum are making it possible to carry out resonance ionization of some of the noble gases. It has already been shown that xenon can be ionized in a two-photon allowed excitation from the ground state. Recently a new method of generating radiation by four-wave mixing in mercury vapor enables excitation of xenon in a one-photon resonance process. With these new laser sources we expect to have effective ionization volumes of 10-3 to 10-2 cm3 for the cases of argon, krypton, and xenon. This has important consequences in weak interaction physics and environmental research

  3. Ionization-chamber smoke detector system

    Science.gov (United States)

    Roe, Robert F.

    1976-10-19

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system is designed to reduce false alarms caused by fluctuations in ambient temperature. Means are provided for periodically firing the gas discharge triode and each time recording the triggering voltage required. A computer compares each triggering voltage with its predecessor. The computer is programmed to energize an alarm if the difference between the two compared voltages is a relatively large value indicative of particulates in the measuring chamber and to disregard smaller differences typically resulting from changes in ambient temperature.

  4. Nucleation in an ultra low ionization environment

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean;

    Atmospheric ions can enhance the nucleation of aerosols, as has been established by experiments, observation, and theory. In the clean marine atmosphere ionization is mainly caused by cosmic rays which in turn are controlled by the activity of the Sun, thus providing a potential link between solar...... Underground Laboratory, located 1100 meters below ground, thus reducing the flux of ionizing cosmic radiation by six orders of magnitude. Similarly we have reduced the gamma background by shielding the experiment in lead and copper. Finally we have used air stored for several weeks and passed through an...... active charcoal filter in order to reduce the Radon concentration. In this way we have been able to make nucleation experiments with very low ionizing background, meaning that we can rule out ion induced nucleation as a contributing mechanism. Our experimental setup is a 50 L electropolished stainless...

  5. Capillary electrophoresis electrospray ionization mass spectrometry interface

    Science.gov (United States)

    Smith, Richard D.; Severs, Joanne C.

    1999-01-01

    The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

  6. Ionizing radiation interactions with DNA: nanodosimetry

    International Nuclear Information System (INIS)

    The metrology of ionizing radiation is based on measuring values that are averaged over macroscopic volume elements, for instance the energy dose is defined as ratio of the energy deposited on the absorber and the absorber mass. For biological or medical radiation effects the stochastic nature of radiation interaction id of main importance, esp. the interaction of ionizing radiation with the DNA as the genetic information carrier. For radiotherapy and risk evaluation purposes a comprehensive system of radiation weighing factors and other characteristics, like radiation quality or relative biological efficacy was developed. The nanodosimetry is aimed to develop a metrological basis relying on physical characteristics of the microscopic structure of ionizing radiation tracks. The article includes the development of experimental nanodosimetric methods, the respective calibration techniques, Monte-Carlo simulation of the particle track microstructure and the correlation nanodosimetry and biological efficiency.

  7. Code of practice for ionizing radiation

    International Nuclear Information System (INIS)

    Prior to 1984, the use of ionizing radiation in Malaysia was governed by the Radioactive Substances Act of 1968. After 1984, its use came under the control of Act 304, called the Atomic Energy Licensing Act 1984. Under powers vested by the Act, the Radiation Protection (Basic Safety Standards) Regulations 1988 were formulated to regulate its use. These Acts do not provide information on proper working procedures. With the publication of the codes of Practice by The Standards and Industrial Research Institute of Malaysia (SIRIM), the users are now able to follow proper guidelines and use ionizing radiation safely and beneficially. This paper discusses the relevant sections in the following codes: 1. Code of Practice for Radiation Protection (Medical X-ray Diagnosis) MS 838:1983. 2. Code of Practice for Safety in Laboratories Part 4: Ionizing radiation MS 1042: Part 4: 1992. (author)

  8. Method and apparatus for analyzing ionizable materials

    International Nuclear Information System (INIS)

    An apparatus and method are described for analyzing a solution of ionizable compounds in a liquid. The solution is irradiated with electromagnetic radiation to ionize the compounds and the electrical conductivity of the solution is measured. The radiation may be X-rays, ultra-violet, infra-red or microwaves. The solution may be split into two streams, only one of which is irradiated, the other being used as a reference by comparing conductivities of the two streams. The liquid must be nonionizable and is preferably a polar solvent. The invention provides an analysis technique useful in liquid chromatography and in gas chromatography after dissolving the eluted gases in a suitable solvent. Electrical conductivity measurements performed on the irradiated eluent provide a quantitative indication of the ionizable materials existing within the eluent stream and a qualitative indication of the purity of the eluent stream. (author)

  9. Multiphoton ionization/dissociation of osmium tetroxide

    International Nuclear Information System (INIS)

    The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO4) have been investigated from measurements of the kinetic energies of product ions (Os+, Os2+, OsO+, O2+, O+) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os+ ionization channel, such as OsO4→OsO4-n+nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os+ ion signal suggests that one or more of the steps leading to Os+ ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow (2+ is shown to result primarily from REMPI of Os+

  10. Ionizing radiation and wild birds: a review

    International Nuclear Information System (INIS)

    Since the first atomic explosion, 16 July 1945 at the Trinity Site in south-central New Mexico, the impact of ionizing radiation on bird populations has been of concern to a few individuals. The proliferation of nuclear power plants has increased public concern as to possible deleterious effects of nuclear power plant operation on resident and migratory bird populations. Literature involving wild birds and ionizing radiation is not readily available, and only a few studies have been anywhere near comprehensive, with most effort directed towards monitoring radionuclide concentration in birds. The objective of the paper is to document the literature on wild birds and ionizing radiation including a brief description of pertinent papers

  11. Ionizing radiation in the food industry

    International Nuclear Information System (INIS)

    The present state of application of ionizing radiation to food irradiation is surveyed. The nature of ionizing radiation, interactions of radiation with matter, dosimetric procedures, and types of radiation sources are outlined. Ionizing radiation is used for sprout inhibition, sterilization, for killing insects, parasites, moulds and fungi, and for enzyme activity inhibition. Sprouting can be stimulated by using low radiation doses. The chemical and biological changes occurring in irradiated foods are discussed. The irradiation of 49 kinds of food is permitted in 36 countries, and is applied on a commercial basis in 20 countries. Examples of large irradiating facilities over the world are given. Attention is also paid to the legislative basis of this approach. (M.D.). 2 tabs., 17 refs

  12. Ionization of atoms by slow heavy particles

    CERN Document Server

    Roberts, B M; Gribakin, G F

    2016-01-01

    Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 sigma annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusp-like behaviour of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, meaning that nonrelativistic calculations m...

  13. Electron impact double ionization of Mg+ ions

    International Nuclear Information System (INIS)

    Electron impact ionization of atoms/ions is one of the fundamental atomic collision processes. Absolute cross sections for electron impact single and multiple ionization are of considerable importance in many fields like astrophysics and controlled nuclear fusion. Theoretical studies of electron impact double ionisation cross sections of Mg+ ions have been performed in the binary encounter approximation (BEA). Direct double ionisation has been investigated in the modified double binary encounter model. Ionization cross sections of different shells have been also calculated in order to analyse the contributions to double ionisation from ionisation-autoionization. The effect of the Coulombic field of the target ion on the incident electron has been considered in the present work. Accurate expression of σΔE (cross-section for energy transfer ΔE) and Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations. The theoretical results show satisfactory agreement with the experimental observations. (authors)

  14. 2. Interaction of ionizing radiation with matter

    International Nuclear Information System (INIS)

    The basic forms of the interaction of ionizing radiation with matter are described, calculations are presented of linear mass stopping power and of the range of charged particles in matter and the effects are described induced by electrons during their passage through matter. A detailed description is given of the types of interaction between photons and matter. Mathematical relations and graphs are given for the angular and energy distribution of particles and for the linear coefficients of attenuation and energy transfer. Described are the elastic and inelastic scattering of neutrons, nuclear reactions and neutron diffusion. Analysed are the effects caused by ionizing radiation in matter: ionization, excitation, luminescence and nuclear processes. (M.D.)

  15. Ionization of atoms by chirped attosecond pulses

    International Nuclear Information System (INIS)

    We investigate the ionization dynamics of atoms by chirped attosecond pulses using the strong field approximation method. The pulse parameters are carefully chosen in the regime where the strong field approximation method is valid. We analyse the effects of the chirp of attosecond pulses on the energy distributions and the corresponding left-right asymmetry of the ionized electrons. For a single chirped attosecond pulse, the ionized electrons can be redistributed and the left-right asymmetry shows oscillations because of the introduction of the chirp. For time-delayed double attosecond pulses at different intensities with the weaker one chirped, exchanging the order of the two pulses shows a relative shift of the energy spectra, which can be explained by the different effective time delays of different frequency components because of the chirp. (atomic and molecular physics)

  16. Advanced Nanoemulsions

    Science.gov (United States)

    Fryd, Michael M.; Mason, Thomas G.

    2012-05-01

    Recent advances in the growing field of nanoemulsions are opening up new applications in many areas such as pharmaceuticals, foods, and cosmetics. Moreover, highly controlled nanoemulsions can also serve as excellent model systems for investigating basic scientific questions about soft matter. Here, we highlight some of the most recent developments in nanoemulsions, focusing on methods of formation, surface modification, material properties, and characterization. These developments provide insight into the substantial advantages that nanoemulsions can offer over their microscale emulsion counterparts.

  17. Advanced LIGO

    OpenAIRE

    Aasi, J.; Abbott, B.; Abbott, R.; Abbott, T.; Abernathy, M; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Adya, V.; Affeldt, C.; Aggarwal, N.; Aguiar, O.; Ain, A.

    2014-01-01

    The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry–Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recyc...

  18. Advanced Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R. [NETL

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  19. Experimental and theoretical triple-differential cross sections for tetrahydrofuran ionized by low-energy 26-eV-electron impact

    Science.gov (United States)

    Ali, Esam; Ren, XueGuang; Dorn, Alexander; Ning, Chuangang; Colgan, James; Madison, Don

    2016-06-01

    We report an experimental and theoretical study of low-energy electron-impact ionization of tetrahydrofuran, which is a molecule of biological interest. The experiments were performed using an advanced reaction microscope specially built for electron-impact ionization studies. The theoretical calculations were performed within the molecular three-body distorted-wave model. Reasonably good agreement is found between experiment and theory.

  20. Thin sums matroids and duality

    CERN Document Server

    Afzali, Hadi

    2012-01-01

    Thin sums matroids were introduced to extend the notion of representability to non-finitary matroids. We give a new criterion for testing when the thin sums construction gives a matroid. We show that thin sums matroids over thin families are precisely the duals of representable matroids (those arising from vector spaces). We also show that the class of tame thin sums matroids is closed under duality and under taking minors, by giving a new characterisation of the matroids in this class. Finally, we show that all the matroids naturally associated to an infinite graph are tame thin sums matroids.