WorldWideScience

Sample records for alpha emitters critical

  1. Alpha particle emitters in medicine

    International Nuclear Information System (INIS)

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 (211At) and natural bismuth-212 (212Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 (223Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs

  2. Alpha particle emitters in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, D.R.

    1989-09-01

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

  3. Critical review for the determination of the minimum detectable activity (MDA) of alpha-emitter radionuclides in environmental samples

    International Nuclear Information System (INIS)

    Different criteria for the calculation of the Minimum Detectable Activity (MDA) of an alpha emitter in environmental levels are reviewed in this report. Practical examples of its application to previously analyzed samples are shown. The authors propose a criteria based on prior calculations that applies to the radiochemical activities performed in the laboratory. The calculation procedure has been discussed with scientist from other laboratories in order to establish a general criteria to calculate the MDA

  4. Alpha-emitters for medical therapy workshop

    Energy Technology Data Exchange (ETDEWEB)

    Feinendegen, L.E.; McClure, J.J.

    1996-12-31

    A workshop on ``Alpha-Emitters for Medical Therapy`` was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference.

  5. Therapeutic use of alpha-emitters

    Energy Technology Data Exchange (ETDEWEB)

    Lassmann, M. [Klinik und Poliklinik fuer Nuklearmedizin der Univ. Wuerzburg (Germany)

    2005-07-01

    In recent years there is a growing interest in the therapeutic use of {alpha}-emitters for patient treatment, {alpha}-particles have much higher energy and their range is only a few cell diameters. Their high LET and the limited ability of cells to repair DNA damage from {alpha}-radiation explain their high relative biological effectiveness and cytotoxicity. Potential {alpha}-emitting isotopes for therapeutic applications are {sup 224}Ra, {sup 223}Ra, {sup 213}Bi and {sup 211}At. The treatment with {alpha}-particles is focused upon targeted cancer therapy using radiolabeled monoclonal antibodies, on palliation of bone metastases or upon pain relief in patients with ankylosing spondylitis (AS). Examples for targeted cancer therapy are the treatment of melanoma with {sup 213}Bi and non-Hodgkin lymphoma with {sup 211}At. For metastatic bone pain palliation {sup 223}Ra was applied in a phase I clinical trial. For amelioration of pain in AS-patients {sup 224}Ra-chloride is used. This radiopharmaceutical is licensed for this particular application in Germany. Today there are some potential clinical applications for {alpha}-emitters although most of them are in the state of scientific, non-routine investigations. In-vivo dosimetry for risk assessment associated with this treatment is even more difficult to perform than for therapies using beta-emitting radiopharmaceuticals. (orig.)

  6. Lyman Alpha Emitter Evolution Through Reionization

    CERN Document Server

    Dayal, P; Saro, A; Salvaterra, R; Borgani, S; Tornatore, L

    2009-01-01

    Combining cosmological SPH simulations with a previously developed Lyman Alpha production/transmission model and the Early Reionization Model (ERM, reionization ends at redshift z~7), we obtain Lyman Alpha and UV Luminosity Functions (LFs) for Lyman Alpha Emitters (LAEs) for redshifts between 5.7 and 7.6. Matching model results to observations at z~5.7 requires escape fractions of Lyman Alpha, f_alpha=0.3, and UV (non-ionizing) continuum photons, f_c=0.22, corresponding to a color excess, E(B-V)=0.15. We find that (i) f_c increases towards higher redshifts, due the decreasing mean dust content of galaxies, (ii) the evolution of f_alpha/f_c hints at the dust content of the ISM becoming progressively inhomogeneous/clumped with decreasing redshift. The clustering photoionization boost is important during the initial reionization phases but has little effect on the Lyman Alpha LF for a highly ionized IGM. With no more free parameters, the Spectral Energy Distributions of three LAE at z~5.7 observed by Lai et al. ...

  7. Signatures of reionization on Lyman alpha emitters

    CERN Document Server

    Dayal, Pratika; Gallerani, Simona

    2008-01-01

    We use a semi-analytic model of Lyman alpha emitters (LAEs) to constrain the reionization history. By considering two physically motivated scenarios in which reionization ends either early (ERM, z_i ~ 7) or late (LRM, z_i ~ 6), we fix the global value of the IGM neutral fraction (e.g. chi_{HI}=3 times 10^{-4}, 0.15 at z=6.56 for the ERM and LRM, respectively) leaving only the star formation efficiency and the effective escape fraction of Lya photons as free parameters. The ERM fits the observed LAE luminosity function (LF) at z=5.7 and 6.56 requiring no redshift evolution or mass dependence of the star formation efficiency, and LAE star formation rates (SFR) of 3-103 solar masses/year, contributing approximately 8% of the cosmic SFR density at z=5.7. The LRM requires a physically uncomfortable drop of approximately 4.5 times in the SFR of the emitters from z=6.5 to 5.7. Thus, the data seem to imply that the Universe was already highly ionized at z=6.56. The mass-dependent Lya transmissivity is between 0.36-0....

  8. Modelling high redshift Lyman-alpha Emitters

    CERN Document Server

    Garel, Thibault; Guiderdoni, Bruno; Schaerer, Daniel; Verhamme, Anne; Hayes, Matthew

    2012-01-01

    We present a new model for high redshift Lyman-Alpha Emitters (LAEs) in the cosmological context which takes into account the resonant scattering of Ly-a photons through expanding gas. The GALICS semi-analytic model provides us with the physical properties of a large sample of high redshift galaxies. We implement a gas outflow model for each galaxy based on simple scaling arguments. The coupling with a library of numerical experiments of Ly-a transfer through expanding or static dusty shells of gas allows us to derive the Ly-a escape fractions and profiles. The predicted distribution of Ly-a photons escape fraction shows that galaxies with a low star formation rate have a f_esc of the order of unity, suggesting that, for those objects, Ly-a may be used to trace the star formation rate assuming a given conversion law. In galaxies forming stars intensely, the escape fraction spans the whole range from 0 to 1. The model is able to get a good match to the UV and Ly-a luminosity function (LF) data at 3 < z <...

  9. Molecular hydrogen in Lyman Alpha Emitters

    CERN Document Server

    Vallini, Livia; Ferrara, Andrea

    2012-01-01

    We present a physically motivated model to estimate the molecular hydrogen (H2) content of high-redshift (z~5.7,6.6) Lyman Alpha Emitters (LAEs) extracted from a suite of cosmological simulations. We find that the H2 mass fraction, (f_H2), depends on three main LAE physical properties: (a) star formation rate, (b) dust mass, and (c) cold neutral gas mass. At z~5.7, the value of f_H2 peaks and ranges between 0.5-0.9 for intermediate mass LAEs with stellar mass M_* ~ 10^{9-10} solar mass, decreasing for both smaller and larger galaxies. However, the largest value of the H2 mass is found in the most luminous LAEs. These trends also hold at z\\sim6.6, although, due to a lower dust content, f_H2(z=6.6)\\sim0.5 f_H2(z=5.7) when averaged over all LAEs; they arise due to the interplay between the H2 formation/shielding controlled by dust and the intensity of the ultraviolet (UV) Lyman-Werner photo-dissociating radiation produced by stars. We then predict the carbon monoxide (CO) luminosities for such LAEs and check tha...

  10. Quantum Estimates of Alpha Emitter Life Time

    Directory of Open Access Journals (Sweden)

    B. Santoso

    2006-01-01

    Full Text Available Quantum estimates of several alpha radioactive life time have been made using the probability of quantum tunneling through the nuclear potential barrier. It is assumed that for a given nucleus with mass number A and isotopic number Z, there exists an alpha particle moving freely back and forth in the nucleus with mass and isotopic numbers A -4 and Z-2. If the probability of penetrating the nuclear potential barrier is Τ, then after N times (N=1/Τ hitting the barrier an alpha particle is emitted. To obtain the elapsed time for emitting an alpha particle requires N times τ0, where τ0 is the time travel for alpha across the nuclear diameter, which is dependent on alpha energy. It is assumed here that this kinetic energy is the same as the emitted energy. The emitting alpha kinetic energies here are calculated by the difference of the masses of the parent and daughter nuclei and the alpha particles. They are in closed agreement with the experimental observations. While the alpha radioactive life time are not the same order of magnitudes but give the same linearity on the logarithmic scale as function of the inverse square root of energy.

  11. Effects of internally deposited alpha emitters

    International Nuclear Information System (INIS)

    This study seeks to identify and quantify the human health effects of occupational exposures to radium, use the health effects data from the radium study to predict responses to other alpha-emitting and/or bone-seeking radionuclides at occupational exposure levels and above, and predict the effects of these radionuclides, specifically environmental radium and its daughters, at nonoccupational exposure levels. 14 refs

  12. Risk estimates for exposure to alpha emitters

    International Nuclear Information System (INIS)

    The primary scope of this report is to evaluate the risk of lung cancer from occupational exposure to short-lived daughters of radon and thoron. The Subcommittee on Risk Estimates considers that inhalation of radon and thoron daughters is the major radiation hazard from alpha radiation in uranium mining. The secondary scope of this report is the consideration of the applicability of the risk estimates derived from miners to the general public. The risk to members of the public from radium-226 in drinking water is also considered. Some research requirments are suggested

  13. Gaseous alpha emitter diffusion studies using alpha track method

    International Nuclear Information System (INIS)

    Using a very accurate and sensitive analysis method such as alpha track method, the SSNTD group was able to undertake studies on the atomic and molecular processes taking place at low speed and/or very low concentrations, such as diffusion of gaseous alpha radionuclides in gaseous media. For practical application reasons, we began to study the diffusion in air for gaseous alpha radionuclides and aerosols carrying solid alpha radionuclides. The used alpha radionuclides were: Rn-222, as gaseous radionuclide and its solid descendants genetically related, attached to different particles from air, as radioactive aerosols. The source was included into an air tight device with a very well known volume. After 40 days, the radioactive equilibrium was established for all descendants, so that in the device there were the Rn-222 and its descendants, each of them having the same activity. The relative amount/activity ratio of each decay product, at any duration, for any initial mass of Ra-226 parent radionuclide, were calculated using the code UURASE, based on the Bateman general equations, for computing the U-238 radioactive series gamma accumulation. This was adapted for alpha accumulation as ALFAURASE programme. The device which contains the Ra-226 source can be coupled to the calibration system or to the diffusion system, without destroying the radioactive equilibrium. At this coupling, only the radioactive concentration is changed due to the variation of the volume. First of all the device was used for calibrating the CR-39 track detectors for both Rn-222 gaseous radionuclide and aerosol concentration measurements using, in the coupled calibration system, a special 'detector-container' equipped/or not with a filter used for radioactive aerosol stopping. The track detectors CR-39 were etched in NaOH 30%, for 7 hours at 70 deg. C and their studies were performed by optical microscopy using a stereo-microscope Wild M7S and a binocular Zeiss Jena microscope. (authors)

  14. Lung cancer risk of low-level exposures to alpha emitters: critical reappraisal and experiments based on a new cytodynamic model

    Energy Technology Data Exchange (ETDEWEB)

    Bogen, Kenneth T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    1999-02-20

    Ecologic U.S. county data suggest negative associations between residential radon exposure and lung cancer mortality (LCM)-inconsistent with clearly positive associations revealed by occupational data on individual miners, but perhaps explained by competing effects of cell killing vs. mutations in alpha-exposed bronchial epithelium. To assess the latter possibility, a biologically based "cytodynamic 2-stage" (CD2) cancer-risk model was fit to combined 1950-54 age- specific person-year data on lung cancer mortality (LCM) in white females of age 40+ y in 2,821 U.S. counties (-90% never-smokers), and in 5 cohorts of underground miners who never smoked. New estimates of household annual average radon exposure in U.S. counties were used, which were found to have a significant negative ecologic association with 1950-54 LCM in U.S. white females, adjusted for age and all subsets of two among 21 socioeconomic, climatic and other factors considered. A good CD2 fit was obtained to the combined residential/miner data, using biologically plausible parameter values. Without further optimization, the fit also predicted independent inverse dose-rate effects shown (for the first time) to occur in nonsmoking miners. Using the same U.S. county-level LCM data, a separate study revealed a positive ecologic association between LCM and bituminous coal use in the U.S., in agreement with epidemiological data on LCM in women in China. The modeling results obtained are consistent with the CD2-based hypothesis that residential radon exposure has a nonlinear U-shaped relation to LCM risk, and that current linear no-threshold extrapolation models substantially overestimate such risk. A U-shaped dose-response corresponds to a CD2-model prediction that alpha radiation kills more premalignant cells than it generates at low exposure levels, but not at higher levels. To test this hypothesis, groups of Japanese medaka (ricefish minnows) were exposed for 10 to 14 weeks to different concentrations of

  15. Joint Ly{\\alpha} emitters - quasars reionization constraints

    CERN Document Server

    Baek, S; Semelin, B

    2012-01-01

    We present a novel method to investigate cosmic reionization, using joint spectral information on high redshift Lyman Alpha Emitters (LAE) and quasars (QSOs). Although LAEs have been proposed as reionization probes, their use is hampered by the fact their Ly{\\alpha} line is damped not only by intergalactic HI but also internally by dust. Our method allows to overcome such degeneracy. First, we carefully calibrate a reionization simulation with QSO absorption line experiments. Then we identify LAEs in two simulation boxes at z=5.7 and z=6.6 and we build synthetic images/spectra of a prototypical LAE. At redshift 5.7, we find that the Ly{\\alpha} transmissivity (T_LAE) ~ 0.25, almost independent of the halo mass. This constancy arises from the conspiracy of two effects: (i) the intrinsic Ly{\\alpha} line width and (ii) the infall peculiar velocity. At higher redshift, z=6.6, where the transmissivity is instead largely set by the local HI abundance and LAE transmissivity consequently increases with halo mass from ...

  16. MIRD Pamphlet No. 22 (Unabridged): Radiobiology and Dosimetry of alpha-Particle Emitters for Targeted Radionuclide Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sgouros, George; Roeske, John C.; McDevitt, Michael S.; Palm, Stig; Allen, Barry J.; Fisher, Darrell R.; Brill, Bertrand A.; Song, Hong; Howell, R. W.; Akabani, Gamal

    2010-02-28

    The potential of alpha-particle emitters to treat cancer has been recognized since the early 1900s. Advances in the targeted delivery of radionuclides, in radionuclide conjugation chemistry, and in the increased availability of alpha-emitters appropriate for clinical use have recently led to patient trials of alpha-particle-emitter labeled radiopharmaceuticals. Although alpha-emitters have been studied for many decades, their current use in humans for targeted therapy is an important milestone. The objective of this work is to review those aspects of the field that are pertinent to targeted alpha-particle-emitter therapy and to provide guidance and recommendations for human alpha-particle-emitter dosimetry.

  17. Determination of substraces of alpha emitter elements in water

    International Nuclear Information System (INIS)

    To determine alpha emitter elements in water by alpha spectrometry, it is necessary to use large volumes of samples, concentration techniq-ues and to separate the elements of interest. In this report a study is presented about two concentration techniques and the process of analysis. Firstly, the stages of concentration method by iron hydroxide coprecipitation were studied in order to improve the results. The combination of liquid-liquid extraction and ion exchange techniques was the best way. Secondly, the technique by adsorption on manganese dioxide was studied. To apply this technique it was necessary to develop analysis methods to separate uranium, thorium, plutonium, americium and radium. These methods were designed combining several techniques of separation: liquid-liquid extraction, liquid-solid extraction, ionic exchange and coprecipitation. After the analysis methods were developped the adsorption on manganese dioxide with artificial samples was studied in the laboratory. Finally, the method of adsorption on manganese dioxide was studied to determine uranium, thorium and radium in the drinking water of Madrid. (Author)

  18. The HETDEX Pilot Survey & 3DHST: What Makes a Lyman-alpha Emitter?

    Science.gov (United States)

    Hagen, Alex; Zeimann, Gregory; Gronwall, Caryl; Ciardullo, Robin; Bridge, Joanna; Hetdex

    2015-01-01

    We compare the 3D-HST H-beta emitters at z~2 to Lyman-alpha emitters found in the same redshift range by the HETDEX Pilot Survey to investigate any differences in the physical and morphological parameters that could elucidate how or why Lyman-alpha is escaping. We use one-dimensional and multi-dimensional statistics, as well as machine learning techniques to try to find differences between these datasets. However, we are unable to find statistically significant differences between these populations. This demonstrates that Lyman-alpha emitters are pulled randomly from the distribution of star-forming galaxies, and there are seemly no strong physical or morphological requirements to be a Lyman-alpha emitter. We also use this information to inform a toy model of Lyman-alpha emission that poses all star-forming galaxies are LAEs if view along certain lines of sight.

  19. Lyman alpha emitter evolution in the reionization epoch

    Science.gov (United States)

    Dayal, P.; Ferrara, A.; Saro, A.; Salvaterra, R.; Borgani, S.; Tornatore, L.

    2009-12-01

    Combining cosmological smoothed particle hydrodynamics (SPH) simulations with a previously developed Lyα production/transmission model and the Early Reionization Model (ERM; reionization ends at redshift z ~ 7), we obtain Lyα and UV luminosity functions (LFs) for lyman alpha emitters (LAEs) at 5.7 ERM. However, during the initial reionization phases (z >~ 7), the clustering photoionization boost becomes important. We quantify the physical properties of observed LAEs and their redshift evolution, for which we give handy analytical fitting functions. Halo (stellar) masses are in the range 10.0 20 Myr at all redshifts, while the mean stellar metallicity increases from Z = 0.12Zsolar at z ~ 7.6 to Z = 0.22Zsolar at z ~ 5.7; both t* and Z positively correlate with stellar mass. The brightest LAEs are all characterized by large and intermediate ages (~200Myr), while objects in the faint end of the Lyα LF show large age and star formation rate spreads. With no more free parameters, the spectral energy distributions of three LAE at z ~ 5.7 observed by Lai et al. (2007) are well reproduced by an intermediate age (182-220 Myr) stellar population and the above E(B - V) value. The model uncertainties, mostly related to the simplified treatment of dust and to the possible effects related to gas outflow/infall, are discussed along with their impact on the results.

  20. Ly-alpha Radiative Transfer in Cosmological Simulations and Application to a z~8 Emitter

    CERN Document Server

    Tasitsiomi, A

    2005-01-01

    We develop a Ly-alpha radiative transfer (RT) Monte Carlo code for cosmological simulations.High resolution,along with appropriately treated cooling can result in simulated environments with very high optical depths.Thus,solving the Ly-alpha RT problem in cosmological simulations can take an unrealistically long time.For this reason,we develop methods to speed up the Ly-alpha RT.With these accelerating methods,along with the parallelization of the code,we make the problem of Ly-alpha RT in the complex environments of cosmological simulations tractable.We test the RT code against simple Ly-alpha emitter models,and then we apply it to the brightest Ly-alpha emitter of a gasdynamics+N-body Adaptive Refinement Tree (ART) simulation at z~8.We find that recombination rather than cooling radiation Ly-alpha photons is the dominant contribution to the intrinsic Ly-alpha luminosity of the emitter,which is ~2.3x10e44 ergs/s.The size of the emitter is pretty small,making it unresolved for currently available instruments....

  1. A device for the remote detection of alpha emitters under field conditions

    NARCIS (Netherlands)

    Simakov, AB

    2005-01-01

    The portable DOP device was designed for the ecological monitoring of the radiation of alpha radioactive nuclides, such as plutonium, uranium, radium, etc. Under field conditions, it can detect alpha emitters at distances of up to 0.5 m. The device's performance data are as follows: the lower thresh

  2. Constraining the Lyman Alpha Escape Fraction with Far-Infrared Observations of Lyman Alpha Emitters

    CERN Document Server

    Wardlow, Julie L; Zheng, Z; Finkelstein, S; Bock, J; Bridge, C; Calanog, J; Ciardullo, R; Conley, A; Cooray, A; Farrah, D; Gawiser, E; Gronwall, C; Heinis, S; Ibar, E; Ivison, R J; Marsden, G; Oliver, S J; Rhoads, J; Riechers, D; Schulz, B; Smith, A J; Viero, M; Wang, L; Zemcov, M

    2013-01-01

    We study the far-infrared properties of 498 Lyman Alpha Emitters (LAEs) at z=2.8, 3.1 and 4.5 in the Extended Chandra Deep Field-South, using 250, 350 and 500 micron data from the Herschel Multi-tiered Extragalactic Survey (HerMES) and 870 micron data from the LABOCA ECDFS Submillimeter Survey (LESS). None of the 126, 280 or 92 LAEs at z=2.8, 3.1 and 4.5, respectively, are individually detected in the far-infrared data. We use stacking to probe the average emission to deeper flux limits, reaching $1\\sigma$ depths of ~0.1 to 0.4 mJy. The LAEs are also undetected at $\\ge3\\sigma$ in the stacks, although a $2.5\\sigma$ signal is observed at 870 micron for the z=2.8 sources. We consider a wide range of far-infrared spectral energy distributions (SEDs), including a M82 and an Sd galaxy template, to determine upper limits on the far-infrared luminosities and far-infrared-derived star-formation rates of the LAEs. These star-formation rates are then combined with those inferred from the Ly$\\alpha$ and UV emission to de...

  3. Optical imaging of alpha emitters: simulations, phantom, and in vivo results

    Science.gov (United States)

    Boschi, Federico; Meo, Sergio Lo; Rossi, Pier Luca; Calandrino, Riccardo; Sbarbati, Andrea; Spinelli, Antonello E.

    2011-12-01

    There has been growing interest in investigating both the in vitro and in vivo detection of optical photons from a plethora of beta emitters using optical techniques. In this paper we have investigated an alpha particle induced fluorescence signal by using a commercial CCD-based small animal optical imaging system. The light emission of a 241Am source was simulated using GEANT4 and tested in different experimental conditions including the imaging of in vivo tissue. We believe that the results presented in this work can be useful to describe a possible mechanism for the in vivo detection of alpha emitters used for therapeutic purposes.

  4. Localization of alpha emitters by damage production in a thin film. Application to the study of alpha emitter diffusion in irradiated samples

    International Nuclear Information System (INIS)

    The process of recording α particles on cellulose nitrate films, called alpha-graphy, is applied to the study of the diffusion of α-emitting elements in irradiated alloys. The existence of diffusion is shown by attacking the film with concentrated caustic soda after exposition. The insensitivity of the recorder to β γ radiation emitted by the sample after passing in the reactor makes it possible to operate with long exposure times and to detect small diffusions. The concentration-penetration curves are drawn up after carrying out a densitometric analysis of the alpha-graphies. - As the cellulose nitrate is affected only by α particles of energies of between 0.5 and 4 MeV, it was first necessary to determine the yield of the recorder for α particles emitted by a thick source, i.e. whose energy varies between 0 and E0, E0 being the energy of the alpha emitter. - The concentration C of the α-emitter, as a function of the optical density D of the alpha-graphy, and of the exposure time t is given by a simple relationship: C = D/at where a is an experimental constant determined by calibration. It depends on the nature of the cellulose nitrate, of the α-emitting element and of the alloy studied. (authors)

  5. Can galactic outflows explain the properties of Ly-alpha emitters?

    CERN Document Server

    Orsi, Alvaro; Baugh, Carlton M

    2011-01-01

    We study the properties of Ly-alpha emitters in a cosmological framework by computing the escape of Ly-alpha photons through galactic outflows. We combine the GALFORM semi-analytical model of galaxy formation with a Monte Carlo Ly-alpha radiative transfer code. The properties of Ly-alpha emitters at 0alpha line profiles predicted by the two outflow geometries in terms of their width, asymmetry and shift from the line centre for a set of outflows with different hydrogen column densities, expansion velocities and metallicities. In general, the Ly-alpha line profile of the Shell geometry is broader and more asymmetric, and the Ly-alpha escape fraction is lower than with the Wind geometry for the same set of parameters. In order to implement the outflow geometries in the semi-analytical model GALFORM, a number of free parameters ...

  6. Alpha emitters in nuclear waste. Extension of the procedure for low and medium level activity waste

    International Nuclear Information System (INIS)

    The present paper describes a separative method for the determination of U, Pu, Am, Np, Th and Cm as alpha emitters and 3H, Sr, and Ni as beta emitters, when present in aqueous samples of nuclear waste, by using chromatographic separations, liquid scintillation counting and alpha spectrometry. The main separation is performed in one step by coprecipitation of the alpha emitters with yttrium hydroxide at pH = 9-10 after distillation of tritium until dryness and dissolution of the residue in 2M HCI. Actinides are precipitated while strontium and nickel remain in supernatant. Nickel is separated by precipitation with dimetyglioxime in the supernatant and measured by LSC. Strontium is separated by chromatography after conditioning the supernatant (which also contained nickel) and measured by LSC. The actinides fraction is re dissolved in nitric acid and percolated through three chromatographic columns (TEVA, U-TEVA and TRU-SPEC) conditioning the different fractions for measuring by alpha spectrometry. The spectra of the different fractions are presented together with the detection limits and the recoveries obtained on spiked samples. (author)

  7. Microscopic dose to lung from inhaled alpha emitters in humans

    International Nuclear Information System (INIS)

    Because of the short range of alpha particles in tissue, the degree of uniformity of irradiation of the lung varies greatly depending on the form of the inhaled material. Animal studies have shown that the degree of dose uniformity influences the risk of lung cancer. This study investigates the radiation dose distribution of plutonium in human lung. Numerical maps of tissue configuration and target cell locations are obtained from histological sections of human lung tissue stained to enhance the identification of putative cell types for parenchymal lung cancers, i.e. alveolar type II cells and Clara cells. Monte Carlo simulations are used to obtain dose distribution around individual particles, and these distributions are used to compute dose distribution in volumes of lung tissue. Lung dose is characterised both by the degree of non-uniformity of irradiation and the relative degree of irradiation of all tissue versus the special cells of interest. (authors)

  8. Rapid determination of alpha emitters using Actinide resin.

    Science.gov (United States)

    Navarro, N; Rodriguez, L; Alvarez, A; Sancho, C

    2004-01-01

    The European Commission has recently published the recommended radiological protection criteria for the clearance of building and building rubble from the dismantling of nuclear installations. Radionuclide specific clearance levels for actinides are very low (between 0.1 and 1 Bq g(-1)). The prevalence of natural radionuclides in rubble materials makes the verification of these levels by direct alpha counting impossible. The capability of Actinide resin (Eichrom Industries, Inc.) for extracting plutonium and americium from rubble samples has been tested in this work. Besides a strong affinity for actinides in the tri, tetra and hexavalent oxidation states, this extraction chromatographic resin presents an easy recovery of absorbed radionuclides. The retention capability was evaluated on rubble samples spiked with certified radionuclide standards (239Pu and 241Am). Samples were leached with nitric acid, passed through a chromatographic column containing the resin and the elution fraction was measured by LSC. Actinide retention varies from 60% to 80%. Based on these results, a rapid method for the verification of clearance levels for actinides in rubble samples is proposed. PMID:15177360

  9. Prolixe-prototype reprocessing unit for irradiating wastes contamined with alpha emitters

    International Nuclear Information System (INIS)

    A large number of hot cells are employed for research on nuclear fuel reprocessing and the production of isotope of transuranium elements. These activities generate solid wastes highly contaminated with alpha, beta, gamma emitters. The Prolixe hot cell was built in order to: 1/ reprocess the solid wastes contaminated with alpha, beta, gamma emitters produced in the Radiochemistry building: 2/ produce package wastes storable in shallow-ground disposal sites: 3/ develop a process sufficiently flexible to make it applicable to waste produced in other installations. The process is based on waste leaching after grinding. Depending on the type of wastes the leaching reactant will have a different composition 1/ nitric acid solution for cellulose waste: 2/ nitric solutions containing Ag(II) for other material. The complete process should achieve: 1/ a high waste volume reduction factor: 2/ the production of immobilized waste packages storage in shallow-ground disposal sites: 3/ the recycling of transuranium elements: 4/ the generation of a minimal volume of effluents. This process can be considered as an alternative process to incineration for the reprocessing of solid wastes highly contaminated with alpha, beta, gamma emitters

  10. Radiative Transfer Modeling of Lyman Alpha Emitters. I. Statistics of Spectra and Luminosity

    OpenAIRE

    Zheng, Zheng; Cen, Renyue; Trac, Hy; Miralda-Escude, Jordi

    2009-01-01

    We combine a cosmological reionization simulation with box size of 100Mpc/h on a side and a Monte Carlo Lyman-alpha (Lya) radiative transfer code to model Lyman Alpha Emitters (LAEs) at z~5.7. The model introduces Lya radiative transfer as the single factor for transforming the intrinsic Lya emission properties into the observed ones. Spatial diffusion of Lya photons from radiative transfer results in extended Lya emission and only the central part with high surface brightness can be observed...

  11. The preformation probability inside Alpha-emitters having different ground state spin-parity than daughters

    CERN Document Server

    Seif, W M; Refaie, A I

    2015-01-01

    The ground-state spin and parity of a formed daughter in the radioactive Alpha-emitter is expected to influence the preformation probability of the Alpha and daughter clusters inside it. We investigate the Alpha and daughter preformation probability inside odd-A and doubly-odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground-state to ground-state unfavored decays. This is to extract precise information about the effect of the difference in the ground states spin-parity of the involved nuclei far away any influences from the excitation energy if the decays are coming from isomeric states. The calculations are done for 161 Alpha-emitters, with Z=65-112 and N=84-173, in the framework of the extended cluster model, with WKB penetrability and assault frequency. We used a Hamiltonian energy density scheme based on Skyrme-SLy4 interaction to compute the interaction potential. The Alpha plus cluster preformation probability is extracted from the calculat...

  12. Studying reionization with the next generation of Ly-alpha emitter surveys

    CERN Document Server

    Jensen, Hannes; Iliev, Ilian; Laursen, Peter; Mellema, Garrelt; Zackrisson, Erik

    2014-01-01

    We study the prospects for constraining the ionized fraction of the intergalactic medium (IGM) at $z>6$ with the next generation of large Ly$\\alpha$ emitter surveys. We make predictions for the upcoming Subaru Hyper Suprime-Cam (HSC) Ly$\\alpha$ survey and a hypothetical spectroscopic survey performed with the James Webb Space Telescope (JWST). Considering various scenarios where the observed evolution of the Ly$\\alpha$ luminosity function of Ly$\\alpha$ emitters at $z>6$ is explained partly by an increasingly neutral IGM and partly by intrinsic galaxy evolution, we show how clustering measurements will be able to distinguish between these scenarios. We find that the HSC survey should be able to detect the additional clustering induced by a neutral IGM if the global IGM neutral fraction is greater than $\\sim$20 per cent at $z=6.5$. If measurements of the Ly$\\alpha$ equivalent widths (EWs) are also available, neutral fractions as small as 10 per cent may be detectable by looking for correlation between the EW an...

  13. The nature of z ~ 2.3 Lyman-alpha emitters

    CERN Document Server

    Nilsson, Kim K; Møller, Palle; Möller-Nilsson, Ole; Tapken, Christian; Freudling, Wolfram; Fynbo, Johan P U

    2010-01-01

    We study the multi-wavelength properties of a set of 171 Ly-alpha emitting candidates at redshift z = 2.25 found in the COSMOS field. The candidates are shown to have different properties from those of Ly-alpha emitters found at higher redshift, by fitting the spectral energy distributions (SEDs) using a Monte-Carlo Markov-Chain technique and including nebular emission in the spectra. The dust contents and stellar masses are both higher, with A_V = 0.0 - 2.0 mag and stellar masses in the range log M_* = 9.0 - 11.0 M_sun. Young population ages are well constrained, but older population ages are typically unconstrained. In 40 % of the galaxies only a single, young population of stars is observed. We show that the ages and Ly-alpha fluxes of the best fit galaxies are correlated with their dust properties, with higher dust extinction in younger galaxies. We conclude that the stellar properties of Ly-alpha emitters at z = 2.25 are different from those at higher redshift and that they are very diverse. Ly-alpha sel...

  14. Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

    CERN Document Server

    Hutter, Anne; Müller, Volker

    2015-01-01

    We calculate Lyman Alpha Emitter (LAE) angular correlation functions (ACFs) at $z\\simeq6.6$ and the fraction of lifetime (for the 100 Myrs preceding $z\\simeq6.6$) galaxies spend as Lyman Break Galaxies (LBGs) with/without Lyman Alpha (Ly\\alpha) emission using a model that combines SPH cosmological simulations (GADGET-2), dust attenuation and a radiative transfer code (pCRASH). The ACFs are a powerful tool that significantly narrows the 3D parameter space allowed by LAE Ly$\\alpha$ and UV luminosity functions (LFs) alone. With this work, we simultaneously constrain the escape fraction of ionizing photons $f_{esc}=0.05-0.5$, the mean fraction of neutral hydrogen in the intergalactic medium (IGM) $\\leq 0.01$ and the dust-dependent ratio of the escape fractions of Ly$\\alpha$ and UV continuum photons $f_\\alpha/f_c=0.6-1.2$. Our results show that reionization has the largest impact on the amplitude of the ACFs, and its imprints are clearly distinguishable from those of $f_{esc}$ and $f_\\alpha/f_c$. We also show that...

  15. A Multiply-Imaged z $\\sim$ 6.3 Lyman Alpha Emitter candidate behind Abell 2261

    CERN Document Server

    Rydberg, Claes-Erik; Zackrisson, Erik; Melinder, Jens; Whalen, Daniel J; Klessen, Ralf S; Gonzalez, Juan; Östlin, Göran; Carollo, Daniela

    2016-01-01

    While the Lyman-$\\alpha$ ($\\mathrm{Ly}\\alpha$) emission line serves as an important tool in the study of galaxies at $z\\lesssim 6$, finding Ly$\\alpha$ emitters (LAE) at significantly higher redshifts has been more challenging, probably because of the increasing neutrality of the intergalactic medium above $z\\sim6$. Galaxies with extremely high rest-frame Ly$\\alpha$ equivalent widths, EW(Ly$\\alpha$) $\\gtrsim 150$ \\AA{}, at $z>6$ are good candidates for Ly$\\alpha$ follow-up observations, and can stand out in multiband imaging surveys because of their unusual colors. We have conducted a photometric search for such objects in the Cluster Lensing And Supernova survey with Hubble (CLASH), and report here the identification of three likely gravitationally-lensed images of a single LAE candidate at $z\\sim6.3$, behind the galaxy cluster Abell 2261($z = 0.225$). In the process, we also measured with Keck/MOSFIRE the first spectroscopic redshift of a multiply-imaged galaxy behind Abell 2261, at $z = 3.337$. This allows ...

  16. Non-linearity between dose and cancer risk for internally deposited alpha emitters in animals

    International Nuclear Information System (INIS)

    The risk of cancer in experimental animals exposed to low doses and dose rates of internally deposited alpha emitting radionuclides was analyzed in 27 animal experiments comprising 78 groups exposed to specific dose levels (dose groups). In these experiments, 3041 animals were exposed to eight different alpha emitters, by injection or by inhalation. Radiation doses ranged from about 60 mGy to more than 7 Gy. There were 1655 control animals. The target organs were the lung and the skeleton. The cancer incidence in exposed groups was compared to that predicted by the Linear No-Threshold Hypothesis (LNTH). In the 3041 exposed animals, 49 cancers were observed, against 83 predicted by the LNTHT. The LNTH appears to be a reliable risk predictor in 11 of the 78 dose groups, but it overestimates the risk in the 67 other dose groups (71 predicted cases, 8 cases observed). No cancer was observed in 53 dose groups, when 23 were predicted by the LNTH. In these 53 dose groups, the probability of not observing a single case of cancer was extremely small. These observations led to the conclusion that, at least in the case of alpha emitters with long physical and biological half-lives, the LNTH is not a good predictor of the risk of cancer. (author)

  17. Limits on the luminosity function of Ly-alpha emitters at z = 7.7

    CERN Document Server

    Hibon, P; Willis, J; Clément, B; Lidman, C; Arnouts, S; Kneib, J -P; Willott, C J; Marmo, C; McCracken, H

    2009-01-01

    The Ly-alpha luminosity function (LF) of high-redshift Ly-alpha emitters (LAEs) is one of the few observables of the re-ionization epoch accessible to date with 8-10 m class telescopes. The evolution with redshift allows one to constrain the evolution of LAEs and their role in re-ionizing the Universe at the end of the Dark Ages. We have performed a narrow-band imaging program at 1.06 microns at the CFHT, targeting Ly-alpha emitters at redshift z ~ 7.7 in the CFHT-LS D1 field. From these observations we have derived a photometric sample of 7 LAE candidates at z ~ 7.7. We derive luminosity functions for the full sample of seven objects and for sub-samples of four objects. If the brightest objects in our sample are real, we infer a luminosity function which would be difficult to reconcile with previous work at lower redshift. More definitive conclusions will require spectroscopic confirmation.

  18. Immuno-vectorization of radioelements emitters of alpha particles: a new therapy in cancerology

    International Nuclear Information System (INIS)

    The radio-immunotherapy is an anti cancerous therapy which consists in vectorising with immuno-specific agents very radio toxic radioelements on tumors or in their environment to destroy them. The first part of this report presents the different characteristics of antibodies as well as their means of production under monoclonal shapes specifically steered against a tumoral antigen of interest. The second part of this report replaces the importance of the immunological vectors in the context of the nuclear medicine. It is notably described that the different methods which allow to radio-label the vector, as well as the different ways of optimization which were envisaged to improve the targeting of radioelements on a tumor. These different developments allow to define the potential place of the alpha radio-immunotherapy in treatments and so re-place the interest of the experimental part. If the radio-immunotherapy, using beta emitters isotopes as the 131iodine or the90yttrium, is today current in anti cancerous therapy, it finds limits because of the disintegration characteristics of the isotopes it uses. Indeed, compared with alpha particles, the beta particles deposit less energy by unit of length in the crossed material.The experimental part of this report aims at studying the feasibility of the coupling between an immunological vector and an alpha emitter isotope.The different tests led on the bismuth 213, the bismuth 212, the lead 212 and the astatine 211 demonstrated that the fixation of these radionuclides was possible. This research theme is strengthened by the construction in Nantes of a cyclotron with high energy ( A.R.R.O.N.A.X.) and the optimization of the obtained promising results should allow a therapeutic use in oncology of the alpha radio-immunotherapy. (N.C.)

  19. Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters

    CERN Document Server

    Verhamme, A; Schaerer, D; Izotov, Y; Worseck, G; Thuan, T X; Guseva, N

    2016-01-01

    We have recently reported the discovery of five low redshift Lyman continuum (LyC) emitters (LCEs, hereafter) with absolute escape fractions fesc(LyC) ranging from 6 to 13%, higher than previously found, and which more than doubles the number of low redshift LCEs.We use these observations to test theoretical predictions about a link between the characteristics of the Lyman-alpha (Lya) line from galaxies and the escape of ionising photons. We analyse the Lya spectra of eight LCEs of the local Universe observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (our five leakers and three galaxies from the litterature), and compare their strengths and shapes to the theoretical criteria and comparison samples of local galaxies: the Lyman Alpha Reference Survey, Lyman Break Analogs, Green Peas, and the high-redshift strong LyC leaker Ion2. Our LCEs are found to be strong Lya emitters, with high equivalent widths, EW(Lya)> 70 {\\AA}, and large Lya escape fractions, fesc(Lya) > 20%. The Lya prof...

  20. Estimates of dose to intraperitoneal micrometastases from alpha and beta emitters in radioimmunotherapy

    International Nuclear Information System (INIS)

    Intraperitoneal metastases from ovarian and other gynecologic tumors are a significant source of treatment failure. In recent years, investigators have used radiolabeled monoclonal antibodies to treat this disease with encouraging results. We have developed a dose calculational technique which generates isodose distributions from intraperitoneally administered alpha and beta particle emitters. In this study we apply the calculations to tissue biopsy samples to determine the adequacy of dose to ovarian micrometastases. Tissue samples from staging biopsies at the time of surgical debulking are scanned to identify small metastases. The patient population studied comprised those with ovarian disease who based on clinical criteria would be considered good candidates for intraperitoneal radioimmunotherapy. The regions of interest (which include the tumor and surface of the peritoneum) are digitized and tumor volumes are contoured. Dose calculations based on the modeling of intraperitoneally administered antibodies radiolabeled with various isotopes is performed and the minimum dose to tumor and normal tissue is assessed. For example, with tumor uptake of 0.1% injected dose per gram of tissue, the surface tumor dose from alpha emitters is up to 45,000 rads. The dose falls to 6000 rads at approximately 40 microns from the peritoneal surface. The surface dose from 20 mCi 90Y administered in 1500 ml saline is up to 10,000 rads, and at a 2-mm depth, approximately 2000 rads. From our calculation dose distribution from radioimmunotherapy varies as a function of physical characteristics of the isotope, absorption of activity, and amount of disease being treated

  1. Studies on the atomic and molecular processes produced by alpha emitters in gaseous media using track detection

    International Nuclear Information System (INIS)

    The main purpose of the studies consists in obtaining new and reliable experimental data on certain atomic and molecular physical processes which take place at low speed or/and very low amounts, such as: diffusion, adherence, fallout, etc. of the alpha emitters in gaseous media. By using the track analysis method, most experimental data can be visualized by optical microscopy, so that reliable qualitative and quantitative investigations can be performed. In the first stage, the alpha track method was used. Two plastic detectors were used: CR - 39 (Page, England) and RL - 115 types 1 and 2 (Kodak, France). For these detectors new etching conditions were developed. In the present stage, a calibration of CR - 39 and RL - 115 track detectors for the alpha particles emitted from gaseous radionuclides, particularly for 222 Rn and its alpha descendants, is performed. For this purpose the track detectors were suspended in tight vessels and the following alpha emitter sources were used: - a diuranate source calibrated in uranium prepared in our laboratory; - a calibrated 226 Ra solution; - sources calibrated in 222 Rn and 226 Ra. The amounts and activities of each alpha decay product of these sources are calculated using a radioactive accumulation computation programme UURASE based on the Bateman general equation. The alpha particle ranges were calculated using the TRIM computation programme. In the future stages of this investigation the following studies will be performed: - the diffusion of gaseous alpha emitters; - the sorption of alpha emitter gases and aerosols on different materials; - 222 Rn monitoring in dwelling houses and working places and the implementation of the alpha track method in the National Networks for surveillance of the environmental alpha radioactivity. (authors)

  2. The Brightest Ly$\\alpha$ Emitter: Pop III or Black Hole?

    CERN Document Server

    Pallottini, A; Pacucci, F; Gallerani, S; Salvadori, S; Schneider, R; Schaerer, D; Sobral, D; Matthee, J

    2015-01-01

    CR7 is the brightest $z=6.6 \\, {\\rm Ly}\\alpha$ emitter (LAE) known to date, and spectroscopic follow-up by Sobral et al. (2015) suggests that CR7 might host Population (Pop) III stars. We examine this interpretation using cosmological hydrodynamical simulations. Several simulated galaxies show the same "Pop III wave" pattern observed in CR7. However, to reproduce the extreme CR7 ${\\rm Ly}\\alpha$/HeII1640 line luminosities ($L_{\\rm \\alpha/He II}$) a top-heavy IMF and a massive ($>10^{7}{\\rm M}_{\\odot}$) PopIII burst with age $10^{43.3}{\\rm erg}\\,{\\rm s}^{-1}$ should also host Pop III stars producing an observable $L_{\\rm He II}>10^{42.7}{\\rm erg}\\,{\\rm s}^{-1}$. As an alternate explanation, we explore the possibility that CR7 is instead powered by accretion onto a Direct Collapse Black Hole (DCBH). Our model predicts $L_{\\alpha}$, $L_{\\rm He II}$, and X-ray luminosities that are in agreement with the observations. In any case, the observed properties of CR7 indicate that this galaxy is most likely powered by s...

  3. Determination the total neutron yields of several semiconductor compounds using various alpha emitters

    Science.gov (United States)

    Abdullah, Ramadhan Hayder; Sabr, Barzan Nehmat

    2016-03-01

    In the present work, the cross-sections of (α,n) reactions available in the literature as a function of α-particle energies for light and medium elements have been rearranged for α-particle energies from near threshold up to 10 MeV in steps of (0.050MeV) using the (Excel and Matlab) computer programs. The obtained data were used to calculate the neutron yields (n/106α) using the quick basic-computer program (Simpson Rules). The stopping powers of alpha particle energies from near threshold to 10 MeV for light and medium elements such as (nat.Be,10B,11B,13C,14N,nat.O,nat.F,nat.Mg,nat.Al,29Si,30Si, nat.P and 46.48Ti) have been calculated using the Zeigler formula. The kinetic energies (Tα) and the branching ratios of each α-emitters such as (211Bi, 210Po, 211Po, 215Po, 217At, 218Rn, 219Rn, 222Rn, 224Ra, 226Ra, 215Th, 228Th, 232U, 234U, 236U, 238U, 238Pu, 239Pu, 241Am, 245Es, 252Fm, 254Fm, 256Fm, 257Fm and 257Md) are taken into consideration to calculate the mean kinetic energy . The polynomial expressions were used to fitting the calculated weighted average of neutron yields (n/106α) for natural light and medium elements such as (Be, B, C, N, O, F, Mg, Al, Si, P and Ti) to determine the adopted neutron yields from the best fitting equation with minimum (CHISQ) at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gx/ppmi) of the mentioned natural light and medium elements have been calculated using the adopted neutron yields (n/106α) from the fitting equations at mean kinetic energies of various α-emitters. The total neutron yields (n/s/gα-emitters/gcompounds) of semiconductor compounds such as (AlN, AlP, BN, BP, SiC, TiO2, BeSiN2, MgCN2, MgSiN2 and MgSiP2) have been calculated by mixing (1gram) of compounds with (1gram) of pure α-emitters using the quick basic computer program. The aim of the present work is to constructed and fabricate the neutron sources theoretically

  4. Alpha Particle Emitter Radiolabeled Antibody for Metastatic Cancer: What Can We Learn from Heavy Ion Beam Radiobiology?

    Directory of Open Access Journals (Sweden)

    Hong Song

    2012-06-01

    Full Text Available Alpha-particle emitter labeled monoclonal antibodies are being actively developed for treatment of metastatic cancer due to the high linear energy transfer (LET and the resulting greater biological efficacy of alpha-emitters. Our knowledge of high LET particle radiobiology derives primarily from accelerated heavy ion beam studies. In heavy ion beam therapy of loco-regional tumors, the modulation of steep transition to very high LET peak as the particle approaches the end of its track (known as the Bragg peak enables greater delivery of biologically potent radiation to the deep seated tumors while sparing normal tissues surrounding the tumor with the relatively low LET track segment part of the heavy ion beam. Moreover, fractionation of the heavy ion beam can further enhance the peak-to-plateau relative biological effectiveness (RBE ratio. In contrast, internally delivered alpha particle radiopharmaceutical therapy lack the control of Bragg peak energy deposition and the dose rate is determined by the administered activity, alpha-emitter half-life and biological kinetics of the radiopharmaceutical. The therapeutic ratio of tumor to normal tissue is mainly achieved by tumor specific targeting of the carrier antibody. In this brief overview, we review the radiobiology of high LET radiations learned from ion beam studies and identify the features that are also applicable for the development of alpha-emitter labeled antibodies. The molecular mechanisms underlying DNA double strand break repair response to high LET radiation are also discussed.

  5. Modelling the Evolution of Ly$\\alpha$ Blobs and Ly$\\alpha$ Emitters

    CERN Document Server

    Smailagić, Marijana; Martinovic, Nemanja

    2016-01-01

    In this work we model the observed evolution in comoving number density of Lyman-alpha blobs (LABs) as a function of redshift, and try to find which mechanism of emission is dominant in LAB. Our model calculates LAB emission both from cooling radiation from the intergalactic gas accreting onto galaxies and from star formation (SF). We have used dark matter (DM) cosmological simulation to which we applied empirical recipes for Ly$\\alpha$ emission produced by cooling radiation and SF in every halo. In difference to the previous work, the simulated volume in the DM simulation is large enough to produce an average LABs number density. At a range of redshifts $z\\sim 1-7$ we compare our results with the observed luminosity functions of LABs and LAEs. Our cooling radiation luminosities appeared to be too small to explain LAB luminosities at all redshifts. In contrast, for SF we obtained a good agreement with observed LFs at all redshifts studied. We also discuss uncertainties which could influence the obtained resul...

  6. The VLT LBG Redshift Survey - V. Characterising the z = 3.1 Lyman Alpha Emitter Population

    CERN Document Server

    Bielby, R M; Shanks, T; Francke, H; Crighton, N H M; Bañados, E; González-López, Jorge; Infante, L; Orsi, A

    2016-01-01

    We present a survey of Ly$\\alpha$ emitting galaxies in the fields of the VLT LBG Redshift Survey, incorporating the analysis of narrow band number counts, the rest frame UV luminosity function and the two-point correlation function of Ly$\\alpha$ emitters at $z\\approx3.1$. Our photometric sample consists of 750 LAE candidates, over an area of 1.07 deg$^2$, with estimated equivalent widths of $\\gtrsim65$ \\AA, from 5 fields based on deep Subaru Suprime-Cam imaging data. Added to this we have obtained spectroscopic follow-up observations, which successfully detected Ly$\\alpha$ emission in 35 galaxies. Based on the spectroscopic results, we refined our photometric selection constraints, with the resulting sample having a success rate of $78\\pm18\\%$. We calculate the narrow band number counts for our photometric sample and find these to be consistent with previous studies of LAEs at this redshift. We find the $R$-band continuum luminosity function to be $\\sim10\\times$ lower than the equivalent luminosity function o...

  7. On the Use of Ly-alpha Emitters as Probes of Reionization

    CERN Document Server

    Jensen, Hannes; Mellema, Garrelt; Iliev, Ilian T; Sommer-Larsen, Jesper; Shapiro, Paul R

    2012-01-01

    We use numerical simulations to study the effects of the patchiness of a partly reionized intergalactic medium (IGM) on the observability of Ly-alpha emitters (LAEs) at high redshifts (z ~ 6). We present a new model that divides the Ly-alpha radiative transfer into a (circum-)galactic and an extragalactic (IGM) part, and investigate how the choice of intrinsic line model affects the IGM transmission results. We use our model to study the impact of neutral hydrogen on statistical observables such as the Ly-alpha restframe equivalent width (REW) distribution, the LAE luminosity function and the two-point correlation function. We find that if the observed changes in LAE luminosity functions and equivalent width distributions between z ~ 6 and z ~ 7 are to be explained by an increased IGM neutral fraction alone, we require an extremely late and rapid reionization scenario, where the Universe was ~ 40 % ionized at z = 7, ~ 50 % ionized at z = 6.5 and ~ 100 % ionized at z = 6. This is in conflict with other observa...

  8. Purification of scintillation cocktails containing the alpha emitters americium and plutonium

    International Nuclear Information System (INIS)

    One efficient way of measuring alpha emitters is by the usage of liquid scintillation counting (LSC). A liquid sample is placed in a vial containing a scintillation cocktail. The alpha particles excite electrons in the surrounding liquid, and when they are de-excited photons are emitted. The photons are detected and the activity can be quantified. LSC has a high efficiency for alpha radiation and is therefore a fast and easy way for measuring alpha emitting samples. One drawback is that it does not differentiate very well between alpha energies; measurements of for example curium and plutonium simultaneously are impossible and demand other techniques. Another drawback is the production of a liquid alpha active waste. In Sweden alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. If, however, the activity of the liquids could be reduced by precipitation of the actinides, it would be possible to send away the liquid samples to municipal incineration. In this work a method for a purification of alpha active scintillation cocktails was developed. The method was first tried on a lab scale, and then scaled up. Until today (March, 2013) more than 20 liters of scintillation liquids have successfully been purified from americium and plutonium at Chalmers University of Technology in Sweden. The four scintillation cocktails used were Emulsifier Safe®, Hionic-Fluor®, Ultima Gold AB® and Ultima Gold XR®. The scintillation cocktails could all be purified from americium with higher yield than 95%. The yield was kept when the liquids were mixed. Also plutonium could be precipitated with a yield over 95% in all cocktails except in Hionic-Fluor® (>55%). However, that liquid in particular could be purified (>95%) by mixing it with the three other cocktails. Up-scaling was performed to a batch size of 6-8 L of scintillation cocktail. In neither the americium nor the plutonium system, adverse effects of increasing the

  9. Early bone changes after incorporation of low quantities of alpha emitters in male rats

    International Nuclear Information System (INIS)

    This work shows the early effects of cancergenic doses of alpha emitters in long bones of rats. The investigations were based on radiographic, morphologic, angiographic, histologic and electronmicroscopic methods. A special method for bone angiography in the rat was elaborated and a new method was developed for measurement of the femur neck-head angle. Numerous disturbances in bone growth and bone structure, in the blood supply of bone and also of the bone building cells were observed. There was a correlation between the severity of the damage and the radiation dose, the spacial distribution of the nuclide and partially the age of the rats. The bone injury due to plutonium was markedly reduced by administration of the chelating agent Zn-DTPA. (orig.)

  10. Radiative Transfer Modeling of Lyman Alpha Emitters: I. Statistics of Spectra and Luminosity

    CERN Document Server

    Zheng, Zheng; Trac, Hy; Miralda-Escude, Jordi

    2009-01-01

    We combine a cosmological reionization simulation with box size of 100Mpc/h on a side and a Monte Carlo Lyman-alpha (Lya) radiative transfer code to model Lyman Alpha Emitters (LAEs) at z~5.7. The model introduces Lya radiative transfer as the single factor for transforming the intrinsic Lya emission properties into the observed ones. Spatial diffusion of Lya photons from radiative transfer results in extended Lya emission and only the central part with high surface brightness can be observed. Because of radiative transfer, the appearance of LAEs depends on density and velocity structures in circumgalactic and intergalactic media as well as the viewing angle, which leads to a broad distribution of apparent (observed) Lya luminosity for a given intrinsic Lya luminosity. Radiative transfer also causes frequency diffusion of Lya photons. The resultant Lya line is asymmetric with a red tail. The peak of the Lya line shifts towards longer wavelength and the shift is anti-correlated with the apparent to intrinsic L...

  11. Exploring the nature of the Lyman-$\\alpha$ emitter CR7

    CERN Document Server

    Hartwig, Tilman; Magg, Mattis; Bromm, Volker; Klessen, Ralf S; Glover, Simon C O; Whalen, Daniel J; Pellegrini, Eric W; Volonteri, Marta

    2015-01-01

    CR7 is the brightest Lyman-$\\alpha$ emitter observed at $z>6$, which shows very strong Lyman-$\\alpha$ and HeII 1640 \\AA\\ line luminosities, but no metal line emission. Previous studies suggest that CR7 hosts either young primordial stars with a total stellar mass of $\\sim 10^7\\,\\mathrm{M}_\\odot$ or a black hole of $\\sim 10^6\\,\\mathrm{M}_\\odot$. Here, we explore different formation scenarios for CR7 with a semianalytical model, based on the random sampling of dark matter merger trees. We find that primordial stars cannot account for the observed line luminosities because of their short lifetimes and because of early metal enrichment. Black holes that are the remnants of the first stars are either not massive enough, or reside in metal-polluted haloes, ruling out this possible explanation of CR7. Our models instead suggest that direct collapse black holes, which form in metal-free haloes exposed to large Lyman-Werner fluxes, are more likely the origin of CR7. However, this result is derived under optimistic ass...

  12. Exploiting 21cm - Ly$\\alpha$ emitter synergies: constraints on reionization

    CERN Document Server

    Hutter, Anne; Müller, Volker; Trott, Cathryn

    2016-01-01

    We couple a $z \\simeq 6.6$ hydrodynamical simulation (GADGET-2) with a radiative transfer code (pCRASH) and a dust model to simultaneously obtain the 21cm emission from the spin-flip transition of neutral hydrogen (HI) as well as the sub-population of galaxies visible as Lyman Alpha Emitters (LAEs). Cross-correlating 21cm data with the underlying galaxy population, and especially the subset visible as LAEs, our aim is to constrain both the average intergalactic medium (IGM) ionization state ($\\langle \\chi_{HI} \\rangle$) and the reionization topology (outside-in versus inside-out). We find that LAEs occupy the densest and most-ionized regions resulting in a very strong anti-correlation between the LAEs and the 21cm emission. Within errors, a 1000h SKA-LOW1 - Subaru Hyper Suprime Cam experiment can provide exquisite constraints on $\\langle \\chi_{HI} \\rangle$, allowing us to distinguish between IGM ionization levels of 50%, 25%, 10% and fully ionized at scales $\\leq 10$ comoving Mpc. Our results support the insi...

  13. Evolution in the properties of Lyman-alpha emitters from redshifts z ~ 3 to z ~ 2

    CERN Document Server

    Nilsson, Kim K; Moeller, Palle; Freudling, Wolfram; Fynbo, Johan P U; Meisenheimer, Klaus; Laursen, Peter; Oestlin, Goeran

    2008-01-01

    Context: Narrow-band surveys for Ly-alpha emitters (LAEs) is a powerful tool in detecting high, and very high, redshift galaxies. Even though samples are growing at redshifts z = 3 - 6, the nature of these galaxies is still poorly known. Aims: To study the properties of z = 2.25 LAEs and compare those with the properties of z > 3 LAEs. Methods: We present narrow-band imaging made with the MPG/ESO 2.2m telescope with the WFI detector. We have made a selection for emission-line objects and find 170 candidate typical LAEs and 17 candidates which we regard as high UV-transmission LAEs. We have derived the magnitudes of these objects in 8 bands from u* to Ks, and studied if they have X-ray and/or radio counterparts. Results: We show that there has been significant evolution in the properties of LAEs between redshift z ~ 3 and z = 2.25. The spread in spectral energy distributions (SEDs) at the lower redshift is larger and we detect a significant AGN contribution in the sample. The distribution of the equivalent wid...

  14. FIRST SPECTROSCOPIC EVIDENCE FOR HIGH IONIZATION STATE AND LOW OXYGEN ABUNDANCE IN Ly{alpha} EMITTERS ,

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Kimihiko; Shimasaku, Kazuhiro; Hashimoto, Takuya; Ono, Yoshiaki [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ouchi, Masami [Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Lee, Janice C., E-mail: nakajima@astron.s.u-tokyo.ac.jp [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2013-05-20

    We present results from Keck/NIRSPEC and Magellan/MMIRS follow-up spectroscopy of Ly{alpha} emitters (LAEs) at z = 2.2 identified in our Subaru narrowband survey. We successfully detect H{alpha} emission from seven LAEs, and perform a detailed analysis of six LAEs free from active galactic nucleus activity, two out of which, CDFS-3865 and COSMOS-30679, have [O II] and [O III] line detections. They are the first [O II]-detected LAEs at high-z, and their [O III]/[O II] ratios and R23-indices provide the first simultaneous determinations of ionization parameter and oxygen abundance for LAEs. CDFS-3865 has a very high ionization parameter (q{sub ion}=2.5{sup +1.7}{sub -0.8} Multiplication-Sign 10{sup 8} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=7.84{sup +0.24}{sub -0.25}) in contrast with moderate values of other high-z galaxies such as Lyman break galaxies (LBGs). COSMOS-30679 also possesses a relatively high ionization parameter (q{sub ion}=8{sup +10}{sub -4} Multiplication-Sign 10{sup 7} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=8.18{sup +0.28}{sub -0.28}). Both LAEs appear to fall below the mass-metallicity relation of z {approx} 2 LBGs. Similarly, a low metallicity of 12 + log (O/H) < 8.4 is independently indicated for typical LAEs from a composite spectrum and the [N II]/H{alpha} index. Such high ionization parameters and low oxygen abundances can be found in local star-forming galaxies, but this extreme local population occupies only {approx}0.06% of the Sloan Digital Sky Survey spectroscopic galaxy sample with a number density {approx}100 times smaller than that of LAEs. With their high ionization parameters and low oxygen abundances, LAEs would represent an early stage of galaxy formation dominated by massive stars in compact star-forming regions. High-q{sub ion} galaxies like LAEs would produce ionizing photons efficiently with a high escape fraction achieved by density-bounded H II regions, which would significantly contribute to

  15. Alpha-risk or quantification of risks associated with chronic exposure to Alpha emitters; Alpha-risk ou la quantification du risque associe a une exposition chronique aux emeteurs ALPHA

    Energy Technology Data Exchange (ETDEWEB)

    Timarche, M. [Institut de Radioprotection et de Surete Nucleaire, DS, 92 - Fontenay-aux-Roses (France)

    2010-07-15

    This article discusses the results obtained by a European research program on long term health risks associated with a chronic internal contamination by alpha radiation emitters. The researchers outlined that, in the case of an exposure to radon, the lung cancer risk, with respect to the cumulative dose, progressively reduces once the exposure has stopped. They also notice that this risk is present for smokers as well as for not smokers

  16. Herschel reveals the obscured star formation in HiZELS H\\alpha\\ emitters at z=1.47

    CERN Document Server

    Ibar, E; Best, P N; Ivison, R J; Smail, I; Arumugam, V; Berta, S; Béthermin, M; Bock, J; Cava, A; Conley, A; Farrah, D; Floc'h, E Le; Lutz, D; Magdis, G; Magnelli, B; Ikarashi, S; Kohno, K; Marsden, G; Oliver, S J; Page, M J; Pozzi, F; Riguccini, L; Schulz, B; Seymour, N; Smith, A J; Symeonidis, M; Wang, L; Wardlow, J; Zemcov, M

    2013-01-01

    We describe the far-infrared (FIR; rest-frame 8--1000\\mu m) properties of a sample of 443 H\\alpha-selected star-forming galaxies in the COSMOS and UDS fields detected by the HiZELS imaging survey. Sources are identified using narrow-band filters in combination with broad-band photometry to uniformly select H\\alpha\\ (and [OII] if available) emitters in a narrow redshift slice at z = 1.47+/-0.02. We use a stacking approach in Spitzer, Herschel (from PEP and HerMES surveys) and AzTEC images to describe their typical FIR properties. We find that HiZELS galaxies with observed H\\alpha\\ luminosities of ~ 10^{8.1-9.1} Lo have bolometric FIR luminosities of typical LIRGs, L_FIR ~ 10^{11.48+/-0.05} Lo. Combining the H\\alpha\\ and FIR luminosities, we derive median SFR = 32+/-5 Mo/yr and H\\alpha\\ extinctions of A(H\\alpha) = 1.0+/-0.2 mag. Perhaps surprisingly, little difference is seen in typical HiZELS extinction levels compared to local star-forming galaxies. We confirm previous empirical stellar mass (M*) to A(H\\alpha...

  17. The BOSS Emission-Line Lens Survey. III. : Strong Lensing of Ly$\\alpha$ Emitters by Individual Galaxies

    CERN Document Server

    Shu, Yiping; Kochanek, Christopher S; Oguri, Masamune; Perez-Fournon, Ismael; Zheng, Zheng; Mao, Shude; Montero-Dorta, Antonio D; Brownstein, Joel R; Marques-Chaves, Rui; Menard, Brice

    2016-01-01

    We introduce the BOSS Emission-Line Lens Survey (BELLS) GALaxy-Ly$\\alpha$ EmitteR sYstems (BELLS GALLERY) Survey, which is a Hubble Space Telescope program to image a sample of galaxy-scale strong gravitational lens candidate systems with high-redshift Ly$\\alpha$ emitters (LAEs) as the background sources. The goal of the BELLS GALLERY Survey is to illuminate dark substructures in galaxy-scale halos by exploiting the small-scale clumpiness of rest-frame far-UV emission in lensed LAEs, and to thereby constrain the slope and normalization of the substructure mass function. In this paper, we describe in detail the spectroscopic strong-lens selection technique, which is based on methods adopted in the previous Sloan Lens ACS (SLACS) Survey, BOSS Emission-Line Lens Survey, and SLACS for the Masses Survey. We present the BELLS GALLERY sample of the 21 highest-quality galaxy-LAE candidates selected from $\\approx 1.4 \\times 10^6$ galaxy spectra in the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital...

  18. DNA double strand breaks as predictor of efficacy of the alpha-particle emitter Ac-225 and the electron emitter Lu-177 for somatostatin receptor targeted radiotherapy.

    Directory of Open Access Journals (Sweden)

    Franziska Graf

    Full Text Available RATIONALE: Key biologic effects of the alpha-particle emitter Actinium-225 in comparison to the beta-particle emitter Lutetium-177 labeled somatostatin-analogue DOTATOC in vitro and in vivo were studied to evaluate the significance of γH2AX-foci formation. METHODS: To determine the relative biological effectiveness (RBE between the two isotopes (as - biological consequence of different ionisation-densities along a particle-track, somatostatin expressing AR42J cells were incubated with Ac-225-DOTATOC and Lu-177-DOTATOC up to 48 h and viability was analyzed using the MTT assay. DNA double strand breaks (DSB were quantified by immunofluorescence staining of γH2AX-foci. Cell cycle was analyzed by flow cytometry. In vivo uptake of both radiolabeled somatostatin-analogues into subcutaneously growing AR42J tumors and the number of cells displaying γH2AX-foci were measured. Therapeutic efficacy was assayed by monitoring tumor growth after treatment with activities estimated from in vitro cytotoxicity. RESULTS: Ac-225-DOTATOC resulted in ED50 values of 14 kBq/ml after 48 h, whereas Lu-177-DOTATOC displayed ED50 values of 10 MBq/ml. The number of DSB grew with increasing concentration of Ac-225-DOTATOC and similarly with Lu-177-DOTATOC when applying a factor of 700-fold higher activity compared to Ac-225. Already 24 h after incubation with 2.5-10 kBq/ml, Ac-225-DOTATOC cell-cycle studies showed up to a 60% increase in the percentage of tumor cells in G2/M phase. After 72 h an apoptotic subG1 peak was also detectable. Tumor uptake for both radio peptides at 48 h was identical (7.5%ID/g, though the overall number of cells with γH2AX-foci was higher in tumors treated with 48 kBq Ac-225-DOTATOC compared to tumors treated with 30 MBq Lu-177-DOTATOC (35% vs. 21%. Tumors with a volume of 0.34 ml reached delayed exponential tumor growth after 25 days (44 kBq Ac-225-DOTATOC and after 21 days (34 MBq Lu-177-DOTATOC. CONCLUSION: γH2AX-foci formation, triggered

  19. Lyman-\\alpha{} Emitters in the context of hierarchical galaxy formation: predictions for VLT/MUSE surveys

    CERN Document Server

    Garel, Thibault; Blaizot, Jérémy

    2015-01-01

    The VLT Multi Unit Spectroscopic Explorer (MUSE) integral-field spectrograph can detect Ly\\alpha{} emitters (LAE) in the redshift range $2.8 \\lesssim z \\lesssim 6.7$ in a homogeneous way. Ongoing MUSE surveys will notably probe faint Ly\\alpha{} sources that are usually missed by current narrow-band surveys. We provide quantitative predictions for a typical wedding-cake observing strategy with MUSE based on mock catalogs generated with a semi-analytic model of galaxy formation coupled to numerical Ly\\alpha{} radiation transfer models in gas outflows. We expect $\\approx$ 1500 bright LAEs ($F_{Ly\\alpha}$ $\\gtrsim$ $10^{-17}$ erg s$^{-1}$ cm$^{-2}$) in a typical Shallow Field (SF) survey carried over $\\approx$ 100 arcmin$^2$, and $\\approx$ 2,000 sources as faint as $10^{-18}$ erg s$^{-1}$ cm$^{-2}$ in a Medium-Deep Field (MDF) survey over 10 arcmin$^2$. In a typical Deep Field (DF) survey of 1 arcmin$^2$, we predict that $\\approx$ 500 extremely faint LAEs ($F_{Ly\\alpha}$ $\\gtrsim$ $4 \\times 10^{-19}$ erg s$^{-1}$...

  20. The HETDEX Pilot Survey V: The Physical Origin of Lyman-alpha Emitters Probed by Near-infrared Spectroscopy

    CERN Document Server

    Song, Mimi; Gebhardt, Karl; Hill, Gary J; Drory, Niv; Ashby, Matthew L N; Blanc, Guillermo A; Bridge, Joanna; Chonis, Taylor; Ciardullo, Robin; Fabricius, Maximilian; Fazio, Giovanni G; Gawiser, Eric; Gronwall, Caryl; Hagen, Alex; Huang, Jia-Sheng; Jogee, Shardha; Livermore, Rachael; Salmon, Brett; Schneider, Donald P; Willner, S P; Zeimann, Gregory R

    2014-01-01

    We present the results from a VLT/SINFONI and Keck/NIRSPEC near-infrared spectroscopic survey of 16 Lyman-alpha emitters (LAEs) at $z$ = 2.1 - 2.5 in the COSMOS and GOODS-N fields discovered from the HETDEX Pilot Survey. We detect rest-frame optical nebular lines (H$\\alpha$ and/or [OIII]$\\lambda$5007) for 10 of the LAEs and measure physical properties, including the star formation rate (SFR), gas-phase metallicity, gas-mass fraction, and Ly$\\alpha$ velocity offset. We find that LAEs may lie below the mass-metallicity relation for continuum-selected star-forming galaxies at the same redshift. The LAEs all show velocity shifts of Ly$\\alpha$ relative to the systemic redshift ranging between +85 and +296 km s$^{-1}$ with a mean of +180 km s$^{-1}$. This value is smaller than measured for continuum-selected star-forming galaxies at similar redshifts. The Ly$\\alpha$ velocity offsets show a moderate correlation with the measured star formation rate (2.5$\\sigma$), but no significant correlations are seen with the SFR...

  1. Theory of the induction of bone sarcoma by bone-seeking alpha emitters and its application to risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Petojan, I.M.

    1992-06-01

    This work discusses the theory of bone sarcoma induction by bone seeking alpha emitters, which is based strictly on biological considerations relative to the mechanism of radiation-induced carcinogenesis, identification of cells at risk and their location in bone, bone tissue renewal processes and bone cell kinetics with or without radiation exposure. The model is consistent with the data on bone sarcoma incidence human with incorporated long-lived isotopes Ra-226 + Ra-228. Extrapolation of these data to a low intake region of the basis of the developed theoretical approach suggests that the linear ICRP-UNSCEAR model overestimates carciogenic risk at low doses, possibly by a factor of 2-4. The model suggests a linear response of target cells to the initiation effects of alpha irradiation. The non-linear (linear-quadratic) initial part of dose-response curve for osteosarcoma induction is explained quantitatively by a model based on a promoter effect of regenerative hyperplasia resulting from invitation effects of alpha radiation. The maximum overestimation inherent to the model of the low-level risk due to the the dose-dependent promotion factor is estimated using bo{sup +1}/bo, where bo is a model parameter which is proportional to the normal division rate of osteogenic cells in vivo and which can be estimated within the framework of the model. The model provides confirming evidence that, for radiation protection purposes, endosteal cells may be considered the only group of cells at risk of sarcoma induction by low doses of bone-seeking alpha emitters, whereas the role of marrow stromal (osteogenic) cells as target cells is much more significant with increasing intakes, and can become dominating if intake is high enough.

  2. Theory of the induction of bone sarcoma by bone-seeking alpha emitters and its application to risk assessment

    International Nuclear Information System (INIS)

    This work discusses the theory of bone sarcoma induction by bone seeking alpha emitters, which is based strictly on biological considerations relative to the mechanism of radiation-induced carcinogenesis, identification of cells at risk and their location in bone, bone tissue renewal processes and bone cell kinetics with or without radiation exposure. The model is consistent with the data on bone sarcoma incidence human with incorporated long-lived isotopes Ra-226 + Ra-228. Extrapolation of these data to a low intake region of the basis of the developed theoretical approach suggests that the linear ICRP-UNSCEAR model overestimates carciogenic risk at low doses, possibly by a factor of 2-4. The model suggests a linear response of target cells to the initiation effects of alpha irradiation. The non-linear (linear-quadratic) initial part of dose-response curve for osteosarcoma induction is explained quantitatively by a model based on a promoter effect of regenerative hyperplasia resulting from invitation effects of alpha radiation. The maximum overestimation inherent to the model of the low-level risk due to the the dose-dependent promotion factor is estimated using bo+1/bo, where bo is a model parameter which is proportional to the normal division rate of osteogenic cells in vivo and which can be estimated within the framework of the model. The model provides confirming evidence that, for radiation protection purposes, endosteal cells may be considered the only group of cells at risk of sarcoma induction by low doses of bone-seeking alpha emitters, whereas the role of marrow stromal (osteogenic) cells as target cells is much more significant with increasing intakes, and can become dominating if intake is high enough

  3. Similarities and uniqueness of Ly$\\alpha$ emitters among star-forming galaxies at z=2.5

    CERN Document Server

    Shimakawa, Rhythm; Shibuya, Takatoshi; Kashikawa, Nobunari; Tanaka, Ichi; Matsuda, Yuichi; Tadaki, Ken-ichi; Koyama, Yusei; Hayashi, Masao; Suzuki, Tomoko L; Yamamoto, Moegi

    2016-01-01

    We conducted a deep narrow-band imaging survey with the Subaru Prime Focus Camera on the Subaru Telescope and constructed a sample of Ly$\\alpha$ emitters (LAEs) at z=2.53 in the UDS-CANDELS field where a sample of H$\\alpha$ emitters (HAEs) at the same redshift is already obtained from our previous narrow-band observation at NIR. The deep narrow-band and multi broadband data allow us to find LAEs of stellar masses and star-formation rates (SFRs) down to $\\gtrsim$$10^8$ M$_\\odot$ and $\\gtrsim$0.2 M$_\\odot$/yr, respectively. We show that the LAEs are located along the same mass-SFR sequence traced by normal star-forming galaxies such as HAEs, but towards a significantly lower mass regime. Likewise, LAEs seem to share the same mass--size relation with typical star-forming galaxies, except for the massive LAEs, which tend to show significantly compact sizes. We identify a vigorous mass growth in the central part of LAEs: the stellar mass density in the central region of LAEs increases as their total galaxy mass gr...

  4. Conception and optimisation of a new apparatus for the radioactive aerosols alpha emitters measurement in real time

    International Nuclear Information System (INIS)

    The measurement of the atmospheric contaminations due to artificial radioelements alpha emitters (239 Pu, 241 Am, 244 Cm,...) is a very difficult problem to resolve because of the three following reasons: the nature of the radiation to detect; very small activities, which correspond to LDCA; existence in the atmosphere of descendants radon and thoron, which are alpha emitters too. To avoid the drawbacks that the present apparatus present, we have conceived, realised and focused a new apparatus based on the following principals: aerosols collection by gas jet technic on solid state support and measurement in real time under a few millibar pression using a solid detector. First of all, we have tried to make the aerosol collection rate better studying the collector nature and dimension influence, the distance between the collector and the gas jet exit and the air flow. Using different supports, we have shown that the energy resolution is not depending on the support nature, but it depends very much on atmospheric conditions. Direct measurements of the radioactive samples are made by the annular detector insered between the nozzle and the collector. The good resolution, the efficacity and the discrimination of natural and artificial contaminations show off the feasibility of this apparatus

  5. Immuno-vectorization of radioelements emitters of alpha particles: a new therapy in cancerology; Immunovectorisation de radioelements emetteurs de particules alpha: une nouvelle voie therapeutique en cancerologie

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, M

    2007-05-15

    The radio-immunotherapy is an anti cancerous therapy which consists in vectorising with immuno-specific agents very radio toxic radioelements on tumors or in their environment to destroy them. The first part of this report presents the different characteristics of antibodies as well as their means of production under monoclonal shapes specifically steered against a tumoral antigen of interest. The second part of this report replaces the importance of the immunological vectors in the context of the nuclear medicine. It is notably described that the different methods which allow to radio-label the vector, as well as the different ways of optimization which were envisaged to improve the targeting of radioelements on a tumor. These different developments allow to define the potential place of the alpha radio-immunotherapy in treatments and so re-place the interest of the experimental part. If the radio-immunotherapy, using beta emitters isotopes as the {sup 131}iodine or the{sup 90}yttrium, is today current in anti cancerous therapy, it finds limits because of the disintegration characteristics of the isotopes it uses. Indeed, compared with alpha particles, the beta particles deposit less energy by unit of length in the crossed material.The experimental part of this report aims at studying the feasibility of the coupling between an immunological vector and an alpha emitter isotope.The different tests led on the bismuth 213, the bismuth 212, the lead 212 and the astatine 211 demonstrated that the fixation of these radionuclides was possible. This research theme is strengthened by the construction in Nantes of a cyclotron with high energy ( A.R.R.O.N.A.X.) and the optimization of the obtained promising results should allow a therapeutic use in oncology of the alpha radio-immunotherapy. (N.C.)

  6. The luminosity function of Ly-alpha emitters at 2.3 < z < 4.6 from integral-field spectroscopy

    CERN Document Server

    Van Breukelen, C; Venemans, B P; Breukelen, Caroline van; Jarvis, Matt J.; Venemans, Bram P.

    2005-01-01

    We have used VIsible MultiObject Spectrograph Integral-Field Unit (VIMOS-IFU) observations centred on a radio galaxy at z=2.9 to search for Ly-alpha emitters within a comoving volume of ~ 10^4 Mpc^3. We find 14 Ly-alpha emitters with flux > 1.4 x 10^-20 Wm^-2, yielding a comoving space density of 0.0018 +/- 0.0006 Mpc^-3. We fit a Schechter luminosity function which agrees well with previous studies both at similar redshift (z ~ 3.4) and higher redshift (z ~ 5.7). We therefore find no evidence for evolution in the properties of Ly-alpha emitters between 3 < z < 6, although our sample is small. By summing the star-formation rates of the individual Ly-alpha emitters we find a total cosmic star-formation rate density of rho_SFR = 6.7 +/- 0.5 x 10^-3 M_solar yr^-1 Mpc^-3. Integrating over the luminosity function for the combined Ly-alpha surveys at z ~ 3.4 and accounting for the difference in obscuration between the Ly-alpha line and the UV-continuum yields an estimate of rho_SFR ~ 2.2 x 10^-2 M_solar yr^-1...

  7. Clinical use of bone-targeting radiopharmaceuticals with focus on alpha-emitters

    Institute of Scientific and Technical Information of China (English)

    Hinrich; A; Wieder; Michael; Lassmann; Martin; S; Allen-Auerbach; Johannes; Czernin; Ken; Herrmann

    2014-01-01

    Various single or multi-modality therapeutic options are available to treat pain of bone metastasis in patients with prostate cancer.Different radionuclides that emitβ-rays such as 153Samarium and 89Strontium and achieve palliation are commercially available.In contrast toβ-emitters,223Radium as a a-emitter has a short path-length.The advantage of the a-emitter is thus a highly localized biological effect that is caused by radiation induced DNA double-strand breaks and subsequent cell killing and/or limited effectiveness of cellular repair mechanisms.Due to the limited range of the a-particles the bone surface to red bone marrow dose ratio is also lower for 223Radium which is expressed in a lower myelotoxicity.The a emitter 223Radium dichloride is the first radiopharmaceutical that significantly prolongslife in castrate resistant prostate cancer patients with wide-spread bone metastatic disease.In a phaseⅢ,randomized,double-blind,placebo-controlled study 921patients with castration-resistant prostate cancer and bone metastases were randomly assigned.The analysis confirmed the 223Radium survival benefit compared to the placebo(median,14.9 mo vs 11.3 mo;P<0.001).In addition,the treatment results in pain palliation and thus,improved quality of life and a delay of skeletal related events.At the same time the toxicity profile of223Radium was favourable.Since May 2013,223Radium dichloride(Xofigo?)is approved by the US Food and Drug Administration.

  8. Clustering of Ly alpha emitters at z approximate to 4.5

    NARCIS (Netherlands)

    Kovac, Katarina; Somerville, Rachel S.; Rhoads, James E.; Malhotra, Sangeeta; Wang, JunXian

    2007-01-01

    We present the clustering properties of 151 Ly alpha-emitting galaxies at z approximate to 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog covers an area of 36'; 36' observed with five narrowband filters. We assume that the angular correlation function w(theta) is well repres

  9. Absolute measurements of the alpha-gamma emitters activities by a sum-coincidence method

    International Nuclear Information System (INIS)

    The absolute activity of U-235 contained in a UO2 sample, using a sum-coincidence circuit which selected only the alpha particles which were simultaneous with the well known 184 Kev gamma radiation from Th-231. The alpha particles were detected by ZnS(Ag) scintillator specially designed to show its maximun efficiency for U-235 alpha particles, whereas the gamma radiation was detected by NaI(Tl) scintillation detector. The values obtained for the half-life of U-235 was compared with data from various observers using different experimental techniques. (Author)

  10. A Dual Narrowband Survey for H\\alpha\\ Emitters at z=2.2: Demonstration of the Technique and Constraints on the H\\alpha\\ Luminosity Function

    CERN Document Server

    Lee, Janice C; Spitler, L; Labbe, I; Salim, S; Persson, S E; Ouchi, M; Dale, D; Monson, A; Murphy, D

    2012-01-01

    We present first results from a narrowband imaging program for intermediate redshift emission-line galaxies using the newly commissioned FourStar infrared camera at the 6.5m Magellan telescope. To enable prompt identification of H\\alpha\\ emitters, a pair of custom 1% filters, which sample low-airglow atmospheric windows at 1.19 \\mu m and 2.10 \\mu m, is used to detect both H\\alpha\\ and [OII]\\lambda 3727 emission from the same redshift volume at z=2.2. Initial observations are taken over a 130 arcmin^2 area in the CANDELS-COSMOS field. The exquisite image quality resulting from the combination of the instrument, telescope, and standard site conditions (~0.55" FWHM) allows the 1.19 \\mu m and 2.10 \\mu m data to probe 3\\sigma\\ emission-line depths down to 1.0e-17 erg/s/cm^2 and 1.2e-17 erg/s/cm^2 respectively, in less than 10 hours of integration time in each narrowband. For H\\alpha\\ at z=0.8 and z=2.2, these fluxes correspond to observed star formation rates of ~0.3 and ~4 Msun/yr respectively. We find 122 source...

  11. On the decreasing fraction of Strong Ly$\\alpha$ Emitters around $z$ $\\sim$ $6$-$7$

    CERN Document Server

    Sadoun, Raphael; Miralda-Escudé, Jordi

    2016-01-01

    The fraction of galaxies with strong Ly$\\alpha$ emission has been observed to decrease rapidly with redshift at $z \\ge 6$, after a gradual increase at $z6$. We study this effect by modeling the ionization and Ly$\\alpha$ radiative transfer in the infall region and the IGM around a Ly$\\alpha$ emitting galaxy (LAE), for a spherical halo model with the mean density and radial velocity profiles in the standard $\\Lambda$CDM cosmological scenario. We find that the expected fast increase of the ionizing background intensity toward the end of the reionization epoch implies a rapid evolution of halo infall regions from being self-shielded against the external ionizing background to being mostly ionized. Whereas self-shielded infall regions can scatter the Ly$\\alpha$ photons over a much larger area than the commonly used apertures for observing LAEs, the same infalling gas is no longer optically thick to the Ly$\\alpha$ emission line after it is ionized by the external background, making the Ly$\\alpha$ emission more comp...

  12. An Ultraluminous Lyman Alpha Emitter with a Blue Wing at z=6.6

    CERN Document Server

    Hu, E M; Songaila, A; Barger, A J; Rosenwasser, B; Wold, I

    2016-01-01

    We report the detection of the most luminous high-redshift Lyman Alpha Emitting galaxy (LAE) yet seen, with log L(Ly alpha) = 43.9 ergs/s. The galaxy -- COSMOS Lyman alpha 1, or COLA1 -- was detected in a search for ultra-luminous LAEs with Hyper Suprime-Cam on the Subaru telescope. It was confirmed to lie at z = 6.593 based on a Lyman alpha line detection obtained from followup spectroscopy with the DEIMOS spectrograph on Keck2. COLA1 is the first very high-redshift LAE to show a multi-component Lyman alpha line profile with a blue wing, which suggests that it could lie in a highly ionized region of the intergalactic medium and could have significant infall. If this interpretation is correct, then ultra-luminous LAEs like COLA1 offer a unique opportunity to determine the properties of the HII regions around these galaxies which will help in understanding the ionization of the z ~ 7 intergalactic medium.

  13. Effect of alpha-radiolysis on the dissolution of UO2 doped with alpha emitters under anoxic conditions

    International Nuclear Information System (INIS)

    The α emissions constitute almost entirely the radiation field of spent nuclear fuel after 500 years in a geological repository. In this work the effect of α-radiolysis on the fuel dissolution in the near field was studied. Pellets of UO2 doped with 10% wt. and 0.1% wt. of ''238 Pu (α-emitter) were prepared using a solgel method which provides homogenous distribution of the dopant in the UO2 matrix. The sintered materials were extensively characterized. Static leaching tests on these materials were carried out under anoxic conditions in deaerated water at room temperature. The results show that the uranium release from the matrix increase for the higher dopant concentration. Under the experimental conditions used it was difficult to observe a clear radiolysis effect on dissolution of the material containing 0.1% wt. of ''238 Pu. In order to study the radiation damage due to α decay in the fluorite type lattice of the UO2, the variation of the lattice parameter as a function of time was measured. An increase of the lattice parameter of approx 0,2% was observed after 1,5 months of storage in the UO2 doped with 10% wt. of plutonium. In the case of the UO2 doped with 0,1% wt. ''238 Pu, the lattice parameter did not vary significantly during the same time interval. The possible effects of damage accumulation on UO2 dissolution are discussed. (Author) 7 refs

  14. A Cose Comparison between Observed and modeled Ly{\\alpha} Lines for z ~ 2.2 Lyman Alpha Emitters

    CERN Document Server

    Hashimoto, Takuya; Ouchi, Masami; Shimasaku, Kazuhiro; Schaerer, Daniel; Nakajima, Kimihiko; Shibuya, Takatoshi; Rauch, Michael; Ono, Yoshiaki; Goto, Ryosuke

    2015-01-01

    We present the results of a Lya profile analysis of 12 Lya emitters (LAEs) at z = 2.2 with high-resolution Lya spectra. We find that all 12 objects have a Lya profile with the main peak redward of the systemic redshift defined by nebular lines, and five have a weak, secondary peak blueward of the systemic redshift (blue bump). The average velocity offset of the red main peak (the blue bump, if any) with respect to the systemic redshift is Delta_v_Lya,r = 174+/- 19 km s-1 (Delta_v_Lya,b = -316+/-45 km s-1), which is smaller than (comparable to) that of Lyman-break galaxies (LBGs). The outflow velocities inferred from metal absorption lines in three individual and one stacked spectra are comparable to those of LBGs. The expanding shell model constructed by Verhamme et al. (2006) reproduces not only the Lya profiles but also other observed quantities including the outflow velocity and the FWHM of nebular lines for the non-blue bump objects. On the other hand, the model predicts too high FWHMs of nebular lines fo...

  15. The WUW ML bundle detector A flow through detector for alpha-emitters

    CERN Document Server

    Wenzel, U; Lochny, M

    1999-01-01

    Using conventional laboratory ware, we designed and manufactured a flow through cell for monitoring alpha-bearing solutions. The cell consists of a bundle of thermoplastic, transparent tubes coated with a thin layer of the meltable scintillator MELTILEX sup T sup M at the inner surface. With appropriate energy windows set, the detector can suppress beta-particles to a great extent due to its geometrical dimensions. For pure alpha-solutions, the detection limits are 5 Bq/ml, for composite nuclide mixtures, the detector is capable to monitor the decontamination of medium active waste (<=10 sup 7 Bq/ml) down to 100 Bq alpha/g solution. At a throughput of 1 ml/s, the pressure build-up amounts to approx 2 bar. We have developed a quality control program to ensure the regularity of the individual bundle loops.

  16. Purification of used scintillation liquids containing the alpha emitters americium and plutonium

    International Nuclear Information System (INIS)

    In Sweden, alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. Therefore, in this work, a method for a purification of alpha active scintillation cocktails was developed. Until today (March, 2013) more than 20 L of scintillation liquids have successfully been purified from americium and plutonium. The products of the process are a solid fraction that can be sent to final storage and a practically non-radioactive liquid fraction that can be sent to municipal incineration. (author)

  17. RADIOACTIVE POSITRON EMITTER PRODUCTION BY ENERGETIC ALPHA PARTICLES IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, R. J. [Code 7650, Naval Research Laboratory, Washington, DC 20375 (United States); Kozlovsky, B. [Tel Aviv University, Tel Aviv (Israel); Share, G. H., E-mail: murphy@ssd5.nrl.navy.mil, E-mail: benz@wise.tau.ac.il, E-mail: share@astro.umd.edu [University of Maryland, College Park, MD 20742 (United States)

    2015-01-01

    Measurements of the 0.511 MeV positron-annihilation line from solar flares are used to explore the flare process in general and ion acceleration in particular. In flares, positrons are produced primarily by the decay of radioactive positron-emitting isotopes resulting from nuclear interactions of flare-accelerated ions with ambient solar material. Kozlovsky et al. provided ion-energy-dependent production cross sections for 67 positron emitters evaluated from their threshold energies (some <1 MeV nucleon{sup –1}) to a GeV nucleon{sup –1}, incorporating them into a computer code for calculating positron-emitter production. Adequate cross-section measurements were available for proton reactions, but not for α-particle reactions where only crude estimates were possible. Here we re-evaluate the α-particle cross sections using new measurements and nuclear reaction codes. In typical large gamma-ray line flares, proton reactions dominate positron production, but α-particle reactions will dominate for steeper accelerated-ion spectra because of their relatively low threshold energies. With the accelerated-{sup 3}He reactions added previously, the code is now reliable for calculating positron production from any distribution of accelerated-ion energies, not just those of typical flares. We have made the code available in the online version of the Journal. We investigate which reactions, projectiles, and ion energies contribute to positron production. We calculate ratios of the annihilation-line fluence to fluences of other gamma-ray lines. Such ratios can be used in interpreting flare data and in determining which nuclear radiation is most sensitive for revealing acceleration of low-energy ions at the Sun.

  18. Ly$\\alpha$ Emitters with Very Large Ly$\\alpha$ Equivalent Widths, EW$_{\\rm 0}$(Ly$\\alpha$) $\\simeq 200-400$ \\AA, at $z\\sim 2$

    CERN Document Server

    Hashimoto, Takuya; Shimasaku, Kazuhiro; Schaerer, Daniel; Nakajima, Kimihiko; Shibuya, Takatoshi; Ono, Yoshiaki; Rauch, Michael; Goto, Ryosuke

    2016-01-01

    We present physical properties of spectroscopically confirmed Ly$\\alpha$ emitters (LAEs) with very large rest-frame Ly$\\alpha$ equivalent widths EW$_{\\rm 0}$(Ly$\\alpha$). Although the definition of large EW$_{\\rm 0}$(Ly$\\alpha$) LAEs is usually difficult due to limited statistical and systematic uncertainties, we identify six LAEs selected from $\\sim 3000$ LAEs at $z\\sim 2$ with reliable measurements of EW$_{\\rm 0}$ (Ly$\\alpha$) $\\simeq 200-400$ \\AA\\ given by careful continuum determinations with our deep photometric and spectroscopic data. These large EW$_{\\rm 0}$(Ly$\\alpha$) LAEs do not have signatures of AGN, but notably small stellar masses of $M_{\\rm *} = 10^{7-8}$ $M_{\\rm \\odot}$ and high specific star-formation rates (star formation rate per unit galaxy stellar mass) of $\\sim 100$ Gyr$^{-1}$. These LAEs are characterized by the median values of $L({\\rm Ly\\alpha})=3.7\\times 10^{42}$ erg s$^{-1}$ and $M_{\\rm UV}=-18.0$ as well as the blue UV continuum slope of $\\beta = -2.5\\pm0.2$ and the low dust extinc...

  19. Were progenitors of local L* galaxies Lyman-alpha emitters at high redshift?

    CERN Document Server

    Yajima, Hidenobu; Zhu, Qirong; Abel, Tom; Gronwall, Caryl; Ciardullo, Robin

    2011-01-01

    The Lya emission has been observed from galaxies over a redshift span z ~ 0 - 8.6. However, the link between high-redshift Lya emitters (LAEs) and local galaxies is largely unknown. Here, we investigate the Lya properties of progenitors of a local L^{*} galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART^2 code. We find that the modeled galaxies are Lya bright in redshift z= 0 - 10. In particular, the Lya luminosities of some massive progenitors at z ~ 2 - 6 are close to the observed characteristic L_{Lya}^{*} of LAEs in that redshift range. Both Lya photon escape fraction and line equivalent width increase with redshift. The Lya escape fraction correlates with a number of physical properties of the galaxy, such as mass, SFR and metallicity. We find a "viewing-angle scatter" in which the photon escape depends strongly on the galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blue-shifted Lya line prof...

  20. Nuclide identification of alpha-emitters by autoradiography in specimen of atomic victims at Nagasaki

    OpenAIRE

    Shichijo, Kazuko; Takatsuji, Toshihiro; Yamamoto, Masayoshi; Nakashima, Masahiro

    2012-01-01

    The explosion of a plutonium Atomic bomb over Nagasaki city in Japan took place at 1102h on August 9, 1945. Radiation dose of A-bomb survivor is practically estimated from external radiation. The alpha particles can be disregarded science they travel only a short distance through air. Plutonium remaining in the soil at Nagasaki after 24yr has been determined in 1971. In the patients subjected to the Atomic bomb there was no evidence of the introduction of radioactive material. We have already...

  1. Effect of the intergalactic environment on the observability of Ly-alpha emitters during reionization

    CERN Document Server

    Iliev, Ilian T; McDonald, Patrick; Mellema, Garrelt; Pen, Ue-Li

    2007-01-01

    Observations of high-redshift Ly-alpha sources are a major tool for studying the high-redshift Universe. We discuss the effect of the reionizing intergalactic medium on the observability of Ly-alpha sources based on large simulations of early structure formation with radiative transfer. This takes into account self-consistently the reionization history, density, velocity and ionization structures and nonlinear source clustering. We find that all fields are highly anisotropic and as a consequence there are very large variations in opacity among the different lines-of-sight. The velocity effects, from both infall and source peculiar velocity are most important for the luminous sources, affecting the line profile and depressing the bright end of the luminosity function. The line profiles are generally asymmetric and the line centers of the luminous sources are always absorbed due to the high density of the local IGM. For both luminous and average sources the damping wing effects are of similar magnitude and rema...

  2. Use of proportional gas scintillator in absolute measurements of alpha-gamma emitter activities

    International Nuclear Information System (INIS)

    The absolute activity of U-235 contained in a U3 O8 sample was measured utilizing a sum-coincidence circuit which selects only the alpha particles which are simultaneous with the 143 KeV and 186 KeV gamma radiations from the Th-231 (product nucleus). The alpha particles were detected by means of a new type of a gas scintillating chamber, in which the light emitted by excitation of the gas atoms, due to the passage of a charged incoming particle, has its intensity increased by the action of an applied electric field. The gamma radiations were detected by means of a NaI(Tl) 1'' x 11/2'' scintillation detector. The value obtained for the half-life of U-235 was compared with the data available from various observers which used different experimental techniques. It is shown tht the results, are in excellent agreement with the best international data available on the subject and that, therefore, the sum-coincidence technique constitutes an important method for such measurements. (Author)

  3. Probing the Physical Properties of z=4.5 Lyman Alpha Emitters with Spitzer

    CERN Document Server

    Finkelstein, Keely D; Tilvi, Vithal; Malhotra, Sangeeta; Rhoads, James E; Grogin, Norman A; Pirzkal, Norbert; Dey, Arjun; Jannuzi, Buell T; Mobasher, Bahram; Pakzad, Sabrina; Salmon, Brett; Wang, Junzian

    2015-01-01

    We present the results from a stellar population modeling analysis of a sample of 162 z=4.5, and 14 z=5.7 Lyman alpha emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 um from the Spitzer Lyman Alpha Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 um for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >3-sigma in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8 to 10^11 Msol. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr - 1 Gyr, while the remainder have ages < 100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8 -- 20 x 10^8 Msol) and young (64 - 570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-bas...

  4. Alpha-emitter radium-223 in the management of solid tumors: current status and future directions.

    Science.gov (United States)

    Nilsson, Sten

    2014-01-01

    Bone metastases, which are commonly seen in patients with advanced cancers, are a major cause of skeletal events, disability, and death. Radium-223 dichloride (radium-223; Xofigo, formerly Alpharadin), a first-in-class, alpha-emitting radiopharmaceutical that selectively targets bone metastases with high-energy short-range alpha-particles, has been approved for the treatment of patients with castration-resistant prostate cancer (CRPC) with symptomatic bone metastases and no known visceral metastases. Approval is based on results of the randomized phase III trial Alpharadin in Symptomatic Prostate Cancer (ALSYMPCA), in which radium-223 prolonged overall survival and time to first symptomatic skeletal event versus placebo among patients with CRPC with symptomatic bone metastases and was generally well tolerated, with low myelosuppression rates and manageable gastrointestinal adverse events. Long-term follow-up of the ALSYMPCA safety population showed that the incidence of myelosuppression remained low among patients treated with radium-223, with no additional safety issues of acute myelogenous leukemia, myelodysplastic syndrome, aplastic anemia, or primary bone cancer within approximately 1.5 years after treatment. The radium-223 overall survival benefit and low toxicity make it an effective, well-tolerated, and novel treatment option for CRPC and symptomatic bone metastases and opens the possibility of exploring radium-223 in the treatment of bone metastases from other cancers. A phase I clinical trial of patients with breast and prostate cancer with skeletal metastases demonstrated that radium-223 was safe and well tolerated at all therapeutically relevant dosages. Moreover, a phase IIa trial of patients with advanced breast cancer and progressive bone-dominant disease demonstrated that radium-223 targeted areas of increased bone metabolism and showed biologic activity. PMID:24857093

  5. Morphological Properties of Lyman Alpha Emitters at Redshift 4.86 in the COSMOS Field: Clumpy Star Formation or Merger?

    CERN Document Server

    Kobayashi, Masakazu A R; Koekemoer, Anton M; Murayama, Takashi; Taniguchi, Yoshiaki; Kajisawa, Masaru; Shioya, Yasuhiro; Scoville, Nick Z; Nagao, Tohru; Capak, Peter L

    2016-01-01

    We investigate morphological properties of 61 Lyman-alpha emitters (LAEs) at z = 4.86 identified in the COSMOS field, based on Hubble Space Telescope Advanced Camera for Surveys (ACS) imaging data in the F814W-band. Out of the 61 LAEs, we find the ACS counterparts for the 54 LAEs. Eight LAEs show double-component structures with a mean projected separation of 0."63 (~ 4.0 kpc at z = 4.86). Considering the faintness of these ACS sources, we carefully evaluate their morphological properties, that is, size and ellipticity. While some of them are compact and indistinguishable from the PSF half-light radius of 0."07 (~ 0.45 kpc), the others are clearly larger than the PSF size and spatially extended up to 0."3 (~ 1.9 kpc). We find that the ACS sources show a positive correlation between ellipticity and size and that the ACS sources with large size and round shape are absent. Our Monte Carlo simulation suggests that the correlation can be explained by (1) the deformation effects via PSF broadening and shot noise or...

  6. Cross-correlation of the cosmic 21-cm signal and Lyman Alpha Emitters during reionization

    CERN Document Server

    Sobacchi, Emanuele; Greig, Bradley

    2016-01-01

    Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal-to-noise, limited by systematics. To confirm a putative 21-cm detection, and check the accuracy of 21-cm data analysis pipelines, it would be very useful to cross-correlate against a genuine cosmological signal. The most promising cosmological signals are wide-field maps of Lyman alpha emitting galaxies (LAEs), expected from the Subaru Hyper-Suprime Cam (HSC) Ultra-Deep field. Here we present estimates of the correlation between LAE maps at z~7 and the 21-cm signal observed by both the Low Frequency Array (LOFAR) and the planned Square Kilometer Array Phase 1 (SKA1). We adopt a systematic approach, varying both: (i) the prescription of assigning LAEs to host halos; and (ii) the large-scale structure of neutral and ionized regions (i.e. EoR morphology). We find that the LAE-21cm cross-correlation...

  7. Impact of Cosmic Variance on the Galaxy-Halo Connection for Lyman-$\\alpha$ Emitters

    CERN Document Server

    Mejia-Restrepo, Julian E

    2016-01-01

    In this paper we study the impact of cosmic variance and observational uncertainties in constraining the mass and occupation fraction, $f_{\\rm occ}$, of dark matter halos hosting Ly-$\\alpha$ Emitting Galaxies (LAEs) at high redshift. To this end, we construct mock catalogs from an N-body simulation to match the typical size of observed fields at $z=3.1$ ($\\sim 1 {\\rm deg^2}$). In our model a dark matter halo with mass in the range $M_{\\rm min}

  8. High-LET alpha-emitters: Radon, lung cancer and smoking

    International Nuclear Information System (INIS)

    The National Academy of Sciences BEIR IV Report deals with the health effects in human populations exposed to internally-deposited alpha-emitting radionuclides and their decay products. Quantitative risk estimates for cancer induction are derived, mainly from analyses of epidemiological data. The Report addresses the health outcomes of exposure to radon and its daughters, primarily lung cancer risks of worker exposure to radon progeny in underground mines and in the general public in indoor domestic environments. An excess relative risk model of lung cancer mortality and exposure to radon progeny is developed; this models the excess risk per Working Level Month in terms of time intervals prior to an attained age, and is dependent on time-since-exposure and age at risk. Risk projections are presented and cover exposure situations of current public health concern. For example, lifetime exposure to 1 WLM y/sup /minus/1/ is estimated to increase the number of deaths due to lung cancer by a factor of about 1.5 over the current rate for both males and females in a population having the current prevalence of cigarette-smoking. Occupational exposure to 4 WLM y/sup /minus/1/ from ages 20 y to 40 y is projected to increase lung cancer deaths by a factor of 1.6 over the current rate of this age cohort in the general population. In all of these cases, most of the increased risk occurs to smokers for whom the risk is up to ten times greater than for non-smokers. 8 refs., 1 tab

  9. Diffuse Lyman Alpha Haloes around Lyman Alpha Emitters at z=3: Do Dark Matter Distributions Determine the Lyman Alpha Spatial Extents?

    CERN Document Server

    Matsuda, Y; Hayashino, T; Yamauchi, R; Nakamura, Y; Morimoto, N; Ouchi, M; Ono, Y; Umemura, M; Mori, M

    2012-01-01

    Using stacks of Ly-a images of 2128 Ly-a emitters (LAEs) and 24 protocluster UV-selected galaxies (LBGs) at z=3.1, we examine the surface brightness profiles of Ly-a haloes around high-z galaxies as a function of environment and UV luminosity. We find that the slopes of the Ly-a radial profiles become flatter as the Mpc-scale LAE surface densities increase, but they are almost independent of the central UV luminosities. The characteristic exponential scale lengths of the Ly-a haloes appear to be proportional to the square of the LAE surface densities (r(Lya) \\propto Sigma(LAE)^2). Including the diffuse, extended Ly-a haloes, the rest-frame Ly-a equivalent width of the LAEs in the densest regions approaches EW_0(Lya) ~ 200 A, the maximum value expected for young (< 10^7 yr) galaxies. This suggests that Ly-a photons formed via shock compression by gas outflows or cooling radiation by gravitational gas inflows may partly contribute to illuminate the Ly-a haloes; however, most of their Ly-a luminosity can be e...

  10. Identification of the brightest Ly\\alpha\\ emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era

    CERN Document Server

    Matthee, Jorryt; Santos, Sérgio; Röttgering, Huub; Darvish, Behnam; Mobasher, Bahram

    2015-01-01

    Using wide field narrow-band surveys, we provide a new measurement of the $z=6.6$ Lyman-$\\alpha$ Emitter (LAE) luminosity function (LF), which constraints the bright end for the first time. We use a combination of archival narrow-band NB921 data in UDS and new NB921 measurements in SA22 and COSMOS/UltraVISTA, all observed with the Subaru telescope, with a total area of $\\sim 5$ deg$^2$. We exclude lower redshift interlopers by using broad-band optical and near-infrared photometry and also exclude three supernovae with data split over multiple epochs. We spectroscopically confirm the two most luminous Ly$\\alpha$ emitters ever found at $z=6.604$ and $6.541$ in the COSMOS field using Keck/DEIMOS and VLT/FORS2. Combining the UDS and COSMOS samples we find no evolution of the bright end of the Ly$\\alpha$ LF between $z=5.7$ and $6.6$, which is supported by spectroscopic follow-up, and conclude that \\emph{Himiko}-like sources are not as rare as previously thought, with number densities of $\\sim 1.5\\times10^{-5}$ Mpc...

  11. Preliminary studies for the determination of alpha emitters using the gross alpha coprecipitation methods; Estudios preliminara para la determinacion de emisores alfa mediante el metodo de coprecipitationd e alfa total

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Navarro, J. A.; Pujol, L.; Suarez, J. A.; Pablo, M. A. de

    2003-07-01

    The radiological quality of drinking water in Spain is regulated by Nuclear Security Guideline No, 7.7 (Rev.1) of the Nuclear Security Council (NSC). this guideline establishes the protocol to follow when the radiological level exceeds 0,1 Bq.l''1. When this level is passed, the responsible alpha emitter must be identified; ''210 Po, ''226Ra, ''230Th, ''239Pu, ''224Ra, ''234 U and ''138 U. Activity due to these isotopes is usually determined using alpha spectrometry with semiconductor detectors. This method allows the activity of the alpha emitters to be determined with a good sensitivity. however, it requires long radiochemical isolations and long counting times, so the method is not suitable for rough estimate radiological analysis. In this preliminary work, we present the conditioning of the sample-precipitate that is essential for further radiochemical isolations. (Author) 9 refs.

  12. Lyman-Alpha Emitter Galaxies at z ~ 2.8 in the Extended Chandra Deep Field-South: I. Tracing the Large-Scale Structure via Lyman-Alpha Imaging

    CERN Document Server

    Zheng, Zhen-Ya; Rhoads, James E; Finkelstein, Steven L; Wang, Jun-Xian; Jiang, Chun-Yan; Cai, Zheng

    2016-01-01

    We present a narrowband survey with three adjacent filters for z=2.8--2.9 Lyman Alpha Emitter (LAE) galaxies in the Extended Chandra Deep Field South (ECDFS), along with spectroscopic followup. With a complete sample of 96 LAEs in the narrowband NB466, we confirm a large-scale structure at z~ 2.8. Compared to the blank field in NB470 and NB475, the LAE density excess in the NB466 field is ~6.0+/-0.8 times the standard deviation expected at z~2.8, assuming a linear bias of 2. The overdense large scale structure in NB466 can be decomposed into 4 protoclusters, whose overdensities are 4.6 - 6.6. These 4 protoclusters are expected to evolve into a Coma-like cluster at z~ 0. In the meanwhile, we investigate the average star-formation rates derived from Ly{\\alpha}, rest-frame UV and X-ray, the Ly{\\alpha} luminosity functions, the Ly{\\alpha} photon densities and their dependence on the environment. We find that the Ly{\\alpha} photon density in the overdense field (NB466) is ~50\\% higher than that in the blank field ...

  13. Critical indices for reversible gamma-alpha phase transformation in metallic cerium

    Science.gov (United States)

    Soldatova, E. D.; Tkachenko, T. B.

    1980-08-01

    Critical indices for cerium have been determined within the framework of the pseudobinary solution theory along the phase equilibrium curve, the critical isotherm, and the critical isobar. The results obtained verify the validity of relationships proposed by Rushbrook (1963), Griffiths (1965), and Coopersmith (1968). It is concluded that reversible gamma-alpha transformation in metallic cerium is a critical-type transformation, and cerium has a critical point on the phase diagram similar to the critical point of the liquid-vapor system.

  14. A High Fraction of Ly-alpha-Emitters Among Galaxies with Extreme Emission Line Ratios at z ~ 2

    CERN Document Server

    Erb, Dawn K; Steidel, Charles C; Strom, Allison L; Rudie, Gwen C; Trainor, Ryan F; Shapley, Alice E; Reddy, Naveen A

    2016-01-01

    Star-forming galaxies form a sequence in the [OIII]/H-beta vs. [NII]/H-alpha diagnostic diagram, with low metallicity, highly ionized galaxies falling in the upper left corner. Drawing from a large sample of UV-selected star-forming galaxies at z~2 with rest-frame optical nebular emission line measurements from Keck-MOSFIRE, we select the extreme ~5% of the galaxies lying in this upper left corner, requiring log([NII]/H-alpha) = 0.75. These cuts identify galaxies with 12 + log(O/H) 20 A. We compare the equivalent width distribution of a sample of 522 UV-selected galaxies at 2.0alpha equivalent width -1 (-4) A, and only 9% of these galaxies qualify as LAEs. The extreme galaxies typically have lower attenuation at Ly-alpha than those in the comparison sample, and have ~50% lower median oxygen abundances. Both factors are likely to facilitate the escape of Ly-alpha: in less dusty galaxies Ly-alpha photons are l...

  15. CHARACTERIZATION OF THE DISTRIBUTION OF THE Ly{alpha} EMITTERS IN THE 53W002 FIELD AT z = 2.4

    Energy Technology Data Exchange (ETDEWEB)

    Mawatari, K.; Yamada, T.; Nakamura, Y. [Astronomical Institute, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Hayashino, T. [Research Center for Neutrino Science, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Matsuda, Y., E-mail: mawatari@astr.tohoku.ac.jp [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

    2012-11-10

    We present the results of our wide-field narrowband imaging of the field around the radio galaxy 53W002 at z = 2.390 with Subaru/Suprime-Cam. A custom-made filter, NB413, centered at 4140 A with a width of 83 A is used to observe the 31' Multiplication-Sign 24' area around the radio galaxy. We detected 204 Ly{alpha} emitters (LAEs) at z = 2.4 with a rest-frame equivalent width larger than 25 A to the depth of 26 AB mag (in NB413). The entire LAE population in the 53W002 field has an average number density and distributions of equivalent width and size that are similar to those of other fields at z {approx} 2. We identify a significant high-density region (53W002F-HDR) that spreads over Almost-Equal-To 5' Multiplication-Sign 4' near 53W002, where the LAE number density is nearly four times as large as the average of the entire field. Using the probability distribution function of density fluctuation, we evaluate the rareness probability of 53W002F-HDR to be 0.9{sup +2.4} {sub -0.62}%, which corresponds to a moderately rich structure. No notable environmental dependency at the comoving scale of 10 Mpc is found for the distributions of the Ly{alpha} equivalent width and luminosity in the field. We also detected four Ly{alpha} blobs, one of which is newly discovered. They are all located in the rims of high-density regions. The biased location and unique morphologies in Ly{alpha} suggest that galaxy interaction plays a key role in their formation.

  16. On the absence of appreciable half-life changes in alpha emitters cooled in metals to 1 Kelvin and below

    CERN Document Server

    Stone, N J; Richards, P; Stone, J R; Veskovic, M; Williams, D A

    2006-01-01

    The recent suggestion that dramatic changes may occur in the lifetime of alpha and beta decay when the activity, in a pure metal host, is cooled to a few Kelvin, is examined in the light of published low temperature nuclear orientation (LTNO) experiments, with emphasis here on alpha decay. In LTNO observations are made of the anisotropy of radioactive emissions with respect to an axis of orientation. Correction of data for decay of metallic samples held at temperatures at and below 1 Kelvin for periods of days and longer has been a routine element of LTNO experiments for many years. No evidence for any change of half life on cooling, with an upper level of less than 1%, has been found, in striking contrast to the predicted changes, for alpha decay, of several orders of magnitude. The proposal that such dramatic changes might alleviate problems of disposal of long-lived radioactive waste is shown to be unrealistic.

  17. Radiolytic oxidation of UO{sub 2} pellets doped with alpha-emitters ({sup 238/239}Pu)

    Energy Technology Data Exchange (ETDEWEB)

    Muzeau, B. [Commissariat a l' Energie Atomique, Rhone Valley Research Center DTCD/SECM/LMPA, BP 17 171, 30207 Bagnols-sur-Ceze Cedex (France); Jegou, C. [Commissariat a l' Energie Atomique, Rhone Valley Research Center DTCD/SECM/LMPA, BP 17 171, 30207 Bagnols-sur-Ceze Cedex (France)], E-mail: christophe.jegou@cea.fr; Delaunay, F. [Commissariat a l' Energie Atomique, Valduc Research Center, 21120 Is-sur-Tille (France); Broudic, V. [Commissariat a l' Energie Atomique, Rhone Valley Research Center DTCD/SECM/LMPA, BP 17 171, 30207 Bagnols-sur-Ceze Cedex (France); Brevet, A. [Commissariat a l' Energie Atomique, Valduc Research Center, 21120 Is-sur-Tille (France); Catalette, H. [Electricite de France, Les Renardieres Research Center, Route de Sens Ecuelles, 77250 Moret-sur-Loing (France); Simoni, E. [Institut de Physique Nucleaire, Bat. 100, 91406 Orsay Cedex (France); Corbel, C. [Laboratoire des Solides Irradies, UMR 7642-CNRS-CEA-Ecole Polytechnique, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2009-01-07

    To assess the impact of alpha radiolysis of water on the oxidative dissolution of UO{sub 2} under anoxic conditions, two series of plutonium-doped samples (specific alpha activity 385 and 18 MBqg{sub UO{sub 2}}{sup -1}) were fabricated, characterized and leached in water of varying complexity (pure water, carbonated water, dissolved hydrogen). Given the very high reactivity of these samples in the presence of air and in order to minimize any prior surface oxidation, a strict experimental protocol was developed based on high-temperature annealing in Ar + 4% H{sub 2} with preleaching cycles. Failure to follow this protocol prevents absolute quantification of oxidation of the UO{sub 2} surface by water radiolysis in solutions. Preoxidation of the pellet surface can lead to uranium release in solution that is dependent on the alpha particle flux, revealing initial oxidation by radiolysis in air including potential traces of water. This makes difficult the accurate quantification of the radiolytic oxidation in water solutions. Controlling the initial surface condition of the samples finally allowed us to demonstrate that radiolytic oxidation in water-saturated media is governed by several threshold effects for which the main parameters are the sample alpha activity and the hydrogen concentration.

  18. An ion guide for the production of a low energy ion beam of daughter products of {alpha}-emitters

    Energy Technology Data Exchange (ETDEWEB)

    Tordoff, B. [Nuclear Physics Group, Schuster Laboratory, Brunswick Street, University of Manchester, Manchester M13 9PL (United Kingdom)]. E-mail: bwt@phys.jyu.fi; Eronen, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Elomaa, V.V. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Gulick, S. [Ernest Rutherford Physics Building, McGill University, 3600 rue University, Montreal, QC, H3A 2T8 (Canada); Hager, U. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Karvonen, P. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Kessler, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Lee, J. [Ernest Rutherford Physics Building, McGill University, 3600 rue University, Montreal, QC, Canada H3A 2T8 (Canada); Moore, I. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Popov, A. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188350 (Russian Federation); Rahaman, S. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Rinta-Antila, S. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Sonoda, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland); Aystoe, J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, 40014 Jyvaeskylae (Finland)

    2006-11-15

    A new ion guide has been modeled and tested for the production of a low energy ({approx}40 kV) ion beam of daughter products of alpha-emitting isotopes. The guide is designed to evacuate daughter recoils originating from the {alpha}-decay of a {sup 233}U source. The source is electroplated onto stainless steel strips and mounted along the inner walls of an ion guide chamber. A combination of electric fields and helium gas flow transport the ions through an exit hole for injection into a mass separator. Ion guide efficiencies for the extraction of {sup 229}Th{sup +} (0.06%), {sup 221}Fr{sup +} (6%) and {sup 217}At{sup +} (6%) beams have been measured. A detailed study of the electric field and gas flow influence on the ion guide efficiency is described for two differing electric field configurations.

  19. An Ion Guide for the Production of a Low Energy Ion Beam of Daughter Products of $\\alpha$-Emitters

    CERN Document Server

    Tordoff, B; Elomaa, V V; Gulick, S; Hager, U; Karvonen, P; Kessler, T; Lee, J; Moore, I; Popov, A; Rahaman, S; Rinta-Antila, S; Sonoda, T; Äystö, J

    2006-01-01

    A new ion guide has been modeled and tested for the production of a low energy ($\\approx$ 40 kV) ion beam of daughter products of alpha-emitting isotopes. The guide is designed to evacuate daughter recoils originating from the $\\alpha$-decay of a $^{233}$U source. The source is electroplated onto stainless steel strips and mounted along the inner walls of an ion guide chamber. A combination of electric fields and helium gas flow transport the ions through an exit hole for injection into a mass separator. Ion guide efficiencies for the extraction of $^{229}$Th$^{+}$ (0.06%), $^{221}$Fr$^{+}$ (6%), and $^{217}$At$^{+}$ (6%) beams have been measured. A detailed study of the electric field and gas flow influence on the ion guide efficiency is described for two differing electric field configurations.

  20. The Rest-Frame Optical Spectroscopic Properties of Ly$\\alpha$-Emitters at $z\\sim2.5$: The Physical Origins of Strong Ly$\\alpha$ Emission

    CERN Document Server

    Trainor, Ryan F; Steidel, Charles C; Rudie, Gwen C

    2016-01-01

    We present rest-frame optical spectra of 60 faint ($R_{AB}\\sim 27$; $L\\sim0.1 L_*$) Ly$\\alpha$-selected galaxies (LAEs) at $z\\approx2.56$. The average LAE is consistent with the extreme low-metallicity end of the continuum-selected galaxy distribution at $z\\approx2-3$. In particular, the LAEs have extremely high [OIII] $\\lambda$5008/H$\\beta$ ratios (log([OIII]/H$\\beta$) $\\sim$ 0.8) and low [NII] $\\lambda$6585/H$\\alpha$ ratios (log([NII]/H$\\alpha$) $<-1.15$). Using the [OIII] $\\lambda$4364 auroral line, we find that the star-forming regions in faint LAEs are characterized by high electron temperatures ($T_e\\approx1.8\\times10^4$K), low oxygen abundances (12 + log(O/H) $\\approx$ 8.04, $Z_{neb}\\approx0.22Z_\\odot$), and high excitations with respect to more luminous galaxies. Our faintest LAEs have line ratios consistent with even lower metallicities, including six with 12 + log(O/H) $\\approx$ 6.9$-$7.4 ($Z_{neb}\\approx0.02-0.05Z_\\odot$). We interpret these observations in light of new models of stellar evoluti...

  1. Large-scale environment of $z\\sim 5.7$ CIV absorption systems -II. Spectroscopy of Lyman-$\\alpha$ emitters

    CERN Document Server

    Díaz, C Gonzalo; Cooke, Jeff; Koyama, Yusei; Ouchi, Masami

    2014-01-01

    The flow of baryons to and from a galaxy, which is fundamental for galaxy formation and evolution, can be studied with galaxy-metal absorption system pairs. Our search for galaxies around CIV absorption systems at $z\\sim5.7$ showed an excess of photometric Lyman-$\\alpha$ emitter (LAE) candidates in the fields J1030+0524 and J1137+3549. Here we present spectroscopic follow-up of 33 LAEs in both fields. In the first field, three out of the five LAEs within 10$h^{{-}1}$ projected comoving Mpc from the CIV system are within $\\pm500$ km s$^{{-}1}$ from the absorption at $z_{\\text{CIV}}=5.7242\\pm0.0001$. The closest candidate (LAE 103027+052419) is robustly confirmed at $212.8^{+14}_{-0.4}h^{-1}$ physical kpc from the CIV system. In the second field, the LAE sample is selected at a lower redshift ($\\Delta z\\sim0.04$) than the CIV absorption system as a result of the filter transmission and, thus, do not trace its environment. The observed properties of LAE 103027+052419 indicate that it is near the high-mass end of...

  2. First direct implications for the dust extinction and star formation of typical Ly{\\alpha} emitters from their faint infrared luminosities

    CERN Document Server

    Kusakabe, Haruka; Nakajima, Kimihiko; Ouchi, Masami

    2014-01-01

    Measuring the IR luminosity of galaxies is crucial for reliably deriving their dust extinction and stellar population. By stacking publicly available deep Spitzer/MIPS 24um and Herschel PACS images for 213 z~2.18 Ly alpha Emitters (LAEs) in the GOODS-South, we obtain a strong upper limit to the IR luminosity of typical high-redshift LAEs and constrain the extinction law for the first time. Our 3sigma upper limit L_{TIR} = 1.1 * 10^{10} L_{sun} gives IRX = L_{TIR}/L_{UV} 44%, are both significantly higher than the cosmic averages at the same epoch. We find that the SMC extinction law is consistent with the IRX and the UV slope beta = -1.4^{+0.2}_{-0.2} of our stacked LAE, while the Calzetti law predicts a 3.8 times higher IRX at this beta. SED fitting using the Calzetti law also gives a ~10 times higher SFR than that calculated from the IR and UV luminosities, SFR_{tot}=1.5-3.3 M_{sun}/yr. With the stellar mass 6.3^{+0.8}_{-2.0} *10^8 M_{sun}, our LAEs lie on a lower-mass extrapolation of the star formation ma...

  3. A hard ionizing spectrum in z=3-4 Ly-alpha emitters with intense [OIII] emission: Analogs of galaxies in the reionization era?

    CERN Document Server

    Nakajima, Kimihiko; Iwata, Ikuru; Inoue, Akio; Kusakabe, Haruka; Ouchi, Masami; Robertson, Brant

    2016-01-01

    We present Keck/MOSFIRE spectra of the diagnostic nebular emission lines [OIII]5007,4959, [OII]3727, and H-beta for a sample of 15 redshift z=3.1-3.7 Ly-alpha emitters (LAEs) and Lyman break galaxies (LBGs). In conjunction with spectra from other surveys, we confirm earlier indications that LAEs have a much higher [OIII]/[OII] line ratio than is seen in similar redshift LBGs. By comparing their distributions on a [OIII]/[OII] versus R23 diagram, we demonstrate that this difference cannot arise solely because of their lower metallicities but most likely is due to a harder ionizing spectrum. Using measures of H-beta and recombination theory, we demonstrate, for a subset of our LAEs, that xi_ion - the number of Lyman continuum photons per UV luminosity - is indeed 0.2-0.5 dex larger than for typical LBGs at similar redshifts. Using photoionization models we estimate the effect this would have on both [OIII]/[OII] and R23 and conclude such a hard spectrum can only partially explain such intense line emission. The...

  4. Kiloparsec Mass/Light Offsets in the Galaxy Pair-Lyman-alpha Emitter Lens System SDSS\\,J1011$+$0143

    CERN Document Server

    Shu, Yiping; Moustakas, Leonidas A; Stern, Daniel; Dey, Arjun; Brownstein, Joel R; Burles, Scott; Spinrad, Hyron

    2016-01-01

    We report the discovery of significant mass/light offsets in the strong gravitational lensing system SDSS\\,J1011$+$0143. We use the high-resolution \\textsl{Hubble Space Telescope} (\\textsl{HST}) F555W- and F814W-band imaging and SDSS spectroscopy of this system, which consists of a close galaxy pair with a projected separation of $\\approx 4.2$ kpc at $z_{\\rm lens} \\sim 0.331$ lensing a Lyman-alpha emitter (LAE) at $z_{\\rm source} = 2.701$. Comparisons between the mass peaks inferred from lens models and light peaks from \\textsl{HST} imaging data reveal significant spatial mass/light offsets as large as $(1.72 \\pm 0.24 \\pm 0.34)$ kpc in both filter bands. Such large mass/light offsets, not seen in isolated field lens galaxies and relaxed galaxy groups, may be related to the interactions between the two lens galaxies. The detected mass/light offsets can potentially serve as an important test for the self-interacting dark matter model. However, other mechanisms such as dynamical friction on spatially differently...

  5. No evidence for Population III stars or a Direct Collapse Black Hole in the z = 6.6 Lyman-$\\alpha$ emitter 'CR7'

    CERN Document Server

    Bowler, R A A; Dunlop, J S; McLeod, D J; Stanway, E R; Eldridge, J J; Jarvis, M J

    2016-01-01

    The z = 6.6 Lyman-$\\alpha$ emitter 'CR7' has been claimed to have a Population III-like stellar population, or alternatively, be a candidate Direct Collapse Black Hole (DCBH). In this paper we investigate the evidence for these exotic scenarios using recently available, deeper, optical, near-infrared and mid-infrared imaging. We find strong Spitzer/IRAC detections for the main component of CR7 at 3.6 and 4.5 microns, and show that it has a blue colour ([3.6] - [4.5] $= -1.2\\pm 0.3$). This colour cannot be reproduced by current Pop. III or pristine DCBH models. Instead, the results suggest that the [3.6] band is contaminated by the [OIII]4959,5007 emission line with an implied rest-frame equivalent width of EW_0 (H$\\beta$ + [OIII]) $\\gtrsim 2000$\\AA. Furthermore, we find that new near-infrared data from the UltraVISTA survey supports a weaker He II 1640 emission line than previously measured, with EW_0 $= 40 \\pm 30$\\AA. For the fainter components of CR7 visible in Hubble Space Telescope imaging, we find no evi...

  6. Does Occipital Alpha Neurofeedback Require Critical Branching to Causally Influence LTRCs and Deterministic ERPs?

    CERN Document Server

    Campbell, Tom

    2016-01-01

    Critical branching is a form of theoretical interaction between simple units, which, in the case of the human brain are assumed to be neuronal elements. Zhigalov, Kaplan, & Palva (Clin Neurophysiol 2016;127:288-89) revealed that neurofeedback flash stimulation phase-locked to high-amplitude occipital alpha influences the stimulus-locked occipital alpha-band averages and the power scaling of long-range temporal correlations of alpha-band amplitude fluctuations. At first, it might seem that neurofeedback influenced critical branching alongside there being an interaction between ongoing neuronal activity and evoked responses. However, the causal relations between these neuronal Long Range Temporal Correlations, sustained attention, and any avalanche dynamics are called into question, as is the assertion of Zhigalov et al. that the neurofeedback flashes are unconsciously processed rather than capturing attention. Uncorrected concerns about false discovery rate and an objective mathematical error in the cited ...

  7. [OIII] emission line as a tracer of star-forming galaxies at high redshifts: Comparison between H$\\alpha$ and [OIII] emitters at $z$=2.23 in HiZELS

    CERN Document Server

    Suzuki, T L; Sobral, D; Khostovan, A A; Hayashi, M; Shimakawa, R; Koyama, Y; Tadaki, K -i; Tanaka, I; Minowa, Y; Yamamoto, M; Smail, I; Best, P N

    2016-01-01

    We investigate the properties of $z$=2.23 H$\\alpha$ and [OIII]$\\lambda$5007 emitters using the narrow-band-selected samples obtained from the High-$z$ Emission Line Survey (HiZELS: Sobral et al. 2013). We construct two samples of the H$\\alpha$ and [OIII] emitters and compare their integrated physical properties. We find that the distribution of stellar masses, dust extinction, star formation rates (SFRs), and specific SFRs, is not statistically different between the two samples. When we separate the full galaxy sample into three subsamples according to the detections of the H$\\alpha$ and/or [OIII] emission lines, most of the sources detected with both H$\\alpha$ and [OIII] show ${\\rm log(sSFR_{UV})}$$\\gtrsim$-9.5. The comparison of the three subsamples suggests that sources with strong [OIII] line emission tend to have the highest star-forming activity out all galaxies that we study. We argue that the [OIII] emission line can be used as a tracer of star-forming galaxies at high redshift, and that it is especia...

  8. Study on the risk of late damage in humans after incorporation of the short-lived alpha emitter Ra-224; Studie zum Risiko von Spaetschaeden beim Menschen nach Inkorporation des kurzlebigen {alpha}-Strahlers Radium-224

    Energy Technology Data Exchange (ETDEWEB)

    Wick, R.R.; Nekolla, E.A.; Kellerer, A.M. [Muenchen Univ. (Germany). Strahlenbiologisches Inst.; Goessner, W. [Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany). Inst. fuer Pathologie

    2003-07-01

    An epidemiological study has been carried out at the GSF - National Research Center for Environment and Health - between 1948 and 1975, on 1460 ankylosing spondylitis (AS) patients. The aim of the study was to ascertain the late health effects suffered by these patients who had received repeated intravenous injections of the short lived {alpha}-emitter {sup 224}Ra. These patients have been followed together with a control group of 1323 ankylosing spondylitis patients not treated with radioactive drugs and/or X-rays. Causes of death have been ascertained for 842 exposed patients and 861 controls by the end of 2002. In the exposed group there has been a total of 219 malignant diseases and 206 cases among the controls. In particular, we observed 15 cases of leukaemia in the exposure group and 8 cases of leukaemia in the control group. Further subclassification of the leukaemias demonstrated a high increase of myeloid leukaemia in the exposure group (9 cases obs. vs. 2.5 cases exp.), and out of these especially the acute myeloid leukaemias (6 cases observed vs. 1.6 expected), whereas in the control group the observed cases are within the expected range (3 myeloid leukaemias vs. 2.6 cases). Out of these 6 cases of myeloid leukaemia, 3 cases have been observed at doses comparable to those of the currently applied {sup 224}Ra treatment with the preparation SpondylAT {sup registered}, in one case the {sup 224}Ra-dose was the 0.6fold, in another case 1.6fold, whereas in one case the total dose could not be verified exactly. The enhanced leukaemia incidence in our exposed group is in line with results from animal experiments in mice having been injected with bone seeking {alpha}-emitters given at low dose rates. (orig.) [German] Im Rahmen einer epidemiologischen Studie werden im GSF-Forschungszentrum 1460 Bechterew-Patienten beobachtet, die in den Jahren 1948 bis 1975 zur Behandlung ihrer Krankheit wiederholte intravenoese Injektionen von {sup 224}Ra erhalten haben. Daneben

  9. Cell survival following alpha particle irradiation: critical sites and implications for carcinogenesis

    International Nuclear Information System (INIS)

    In experiments in which mammalian cells were irradiated with 5.6 MeV alpha particles from a Tandem Van de Graaff machine we have confirmed the finding of others that the mean lethal dose (D0) is about 100 rad, but by measurements of the area of the cell nuclei as irradiated we found that this mean lethal dose corresponds not to 1, as expected, but to about 27 alpha particles per cell nucleus. (The exact number appears to change slightly with cell passage number.) This allows for the possibility that the direct action of alpha particles on the nucleus may be the important event in carcinogenesis, a theory which was previously difficult to accept if a single particle hitting the nucleus anywhere was considered to be lethal. Evidence is presented to implicate the nucleolus as a possible critical site for the inhibition of reproductive integrity of the cell

  10. Targeted therapy using alpha emitters

    Science.gov (United States)

    Vaidyanathan, Ganesan; Zalutsky, Michael R.

    1996-10-01

    Radionuclides such as and which decay by the emission of -particles are attractive for certain applications of targeted radiotherapy. The tissue penetration of and -particles is equivalent to only a few cell diameters, offering the possibility of combining cell-specific targeting with radiation of similar range. Unlike the -particles emitted by radionuclides such as and , -particles are radiation of high linear energy transfer and thus greater biological effectiveness. Several approaches have been explored for targeted radiotherapy with - and -labelled substances including colloids, monoclonal antibodies, metabolic precursors, receptor-avid ligands and other lower molecular weight molecules. An additional agent which exemplifies the promise of -emitting radiopharmaceuticals is meta-[]astatobenzylguanidine. The toxicity of this compound under single-cell conditions, determined both by []thymidine incorporation and by limiting dilution clonogenic assays, for human neuroblastoma cells is of the order of 1000 times higher than that of meta-[]iodobenzylguanidine. For meta-[]astatobenzylguanidine, the value was equivalent to only atoms bound per cell. These results suggest that meta-[]astatobenzylguanidine might be valuable for the targeted radiotherapy of micrometastatic neuroblastomas.

  11. Cancer from internal emitters

    International Nuclear Information System (INIS)

    Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of 226Ra or medical injections of 224Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes

  12. A remarkably high fraction of strong Ly_alpha emitters amongst luminous redshift 6.0

    CERN Document Server

    Curtis-Lake, E; Pearce, H J; Dunlop, J S; Cirasuolo, M; Stark, D P; Almaini, O; Bradshaw, E J; Chuter, R; Foucaud, S; Hartley, W G

    2011-01-01

    We present spectroscopic confirmation of ten highly luminous (L >= 2L*) Lyman alpha emitters in the redshift range 6.01= 6 Lyman break galaxies (LBGs) selected from an area of 0.25 square degrees within the UKIDSS Ultra-deep Survey (UDS). Overall, our high rate of spectroscopic confirmation (>= 71%) and low rate of contamination provides a strong vindication of the photometric redshift analysis used to define the original sample. By considering star-formation rate estimates based on the Ly_alpha and UV continuum luminosity we conclude that our sample is consistent with a Ly_alpha escape fraction of ~25%. Moreover, after careful consideration of the potential uncertainties and biases, we find that 40%-50% of our sample of L >= 2L* galaxies at 6.0= 25 Angs), a fraction which is a factor of ~2 higher than previously reported for L =2 L*) LBGs shows a similarly sharp increase to that observed in their lower-luminosity (L <= L*) counterparts.

  13. Leaching of UO2 pellets doped with alpha-emitters (238/239Pu) in synthetic deep Callovian-Oxfordian groundwater

    Science.gov (United States)

    Tribet, M.; Jégou, C.; Broudic, V.; Marques, C.; Rigaux, P.; Gavazzi, A.

    2010-03-01

    The reactivity of a polycrystalline UO2 surface under alpha irradiation in contact with groundwater is investigated, in the hypothesis of direct disposal of spent fuel in a deep geological repository. Two series of plutonium-doped UO2 samples (specific alpha activity of 18 and 385 MBq·g-1UO2) were leached in a synthetic Callovian-Oxfordian deep groundwater under anoxic conditions (Ar/CO2 3000 ppm, 3.5 bar relative pressure) to assess both the impact of alpha radiolysis of water and the complexing capacity of the groundwater ions on the dissolution of UO2. This study follows a prior one performed in pure and carbonated waters. Firstly, technical developments were necessary for the analyses in the groundwater solution because of its high salt concentrations: quantification limits were determined for the measurement of uranium and radiolytic H2O2 traces in this medium. Secondly, given the very high reactivity of these samples in the presence of air and in order to minimize any prior surface oxidation, a strict experimental protocol was followed, based on high-temperature annealing in Ar + 4% H2 with preleaching cycles. Each type of UO2 pellet was then leached under static conditions for 30 days (anoxic conditions, deep groundwater solutions). Results on the evolution of uranium releases are presented. For the lowest alpha activity (18 MBq·g-1UO2), uranium releases in groundwater were below the quantification limit of 2 × 10-8 mol·L-1 with a kinetic phosphorescence analyzer, even after 30 days. However, for higher alpha activity (385 MBq·g-1UO2) the uranium releases begin to exceed the quantification limit after 14 days of leaching and then increase exponentially. This increase is comparable to results previously obtained in carbonated solutions.

  14. Novel method to assessing and the impact of alpha emitter's concentration of the uterus on women fertility in Iraqi Kurdistan region

    International Nuclear Information System (INIS)

    In the present work, 30 uterine tissue samples were collected from women with uterine problems from Iraqi Kurdistan. Tissue samples were analyzed and examined to measure levels of concentrated α-particle emitters and their short-lived decay products using a plastic track detector (CR-39) and the PVC long-tube technique with standard source radium (226Ra). A new method and apparatus for the passive sampling of α-particles were also introduced. The maximum 0.0691 ppm and minimum 0.0180 ppm concentrations of particles were found in Sedakan and in Dukan, respectively; the average value was 0.0330 ppm, when compared the result with the result (0.12 ppm) in Asumadu-Sakyi et al. (Res J Environ Earth Sci 3(1):24-31, 2011) is lower than it and is agree with the result in Rubyie (Radioactive detection on the blood samples of cancer patients diseases by using CR-39 detector and its effect on cytogenetic. MSc. thesis, Al-Nahrain University, 2007). Also the results of fresh uterus are Significant (p 222Rn gas varied from one woman to another depending on her age, the allergic reaction of her uterus to the radiation, and the geological formation of the area under study. The hazardous effects of α-particles are caused by increasing levels of ionizing radiation in the environment. (author)

  15. MUSE integral-field spectroscopy towards the Frontier Fields cluster Abell S1063: II. Properties of low luminosity Lyman alpha emitters at z>3

    CERN Document Server

    Karman, W; Caminha, G B; Gronke, M; Grillo, C; Balestra, I; Rosati, P; Vanzella, E; Coe, D; Dijkstra, M; Koekemoer, A M; Mercurio, A; Nonino, M

    2016-01-01

    In spite of their conjectured importance for the Epoch of Reionization, the properties of low-mass galaxies are currently still under large debate. In this article, we study the stellar and gaseous properties of faint, low-mass galaxies at z>3. We observed the Frontier Fields cluster Abell S1063 with MUSE over a 2 arcmin^2 field, and combined integral-field spectroscopy with gravitational lensing to perform a blind search for intrinsically faint Lya emitters (LAEs). We found in total 14 lensed LAEs and increased the number of spectroscopically-confirmed multiple-image families from 6 to 17, and updated our gravitational-lensing model accordingly. The lensing-corrected Lya luminosities are with L(Lya) =3 are reported. We performed SED modelling to broadband photometry from the {\\em U}-band through the infrared to determine the stellar properties of these LAEs. The stellar masses are very low (10^{6-8} Msun), and are accompanied by very young ages of 1-100 Myr. The very high specific star formation rates (~100/...

  16. Aberration Corrected Emittance Exchange

    CERN Document Server

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  17. A New Population of High-z, Dusty Lyman-alpha Emitters and Blobs Discovered by WISE: Feedback Caught in the Act?

    Science.gov (United States)

    Bridge, Carrie R.; Blain, Andrew; Borys, Colin J. K.; Petty, Sara; Benford, Dominic; Eisenhardt, Peter; Farrah, Duncan; Griffith, Roger, L.; Jarrett, Tom; Lonsdale, Carol; Stanford. Spencer A.; Stern, Daniel; Tsai, Chao-Wei; Wright, Edward L.; Wu, Jingwen

    2013-01-01

    By combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W. M. Keck telescope, we discover a mid-IR color criterion that yields a 78% success rate in identifying rare, typically radio-quiet, 1.6 approx. 10(exp 13)-10(exp 14) Solar L) and have warm colors. They are typically more luminous and warmer than other dusty, z approx.. 2 populations such as submillimeter-selected galaxies and dust-obscured galaxies. These traits are commonly associated with the dust being illuminated by intense active galactic nucleus activity. We hypothesize that the combination of spatially extended Ly-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing brief, intense "feedback" transforming them from an extreme dusty starburst/QSO into a mature galaxy.

  18. A Critical Review of Alpha Radionuclide Therapy-How to Deal with Recoiling Daughters?

    Science.gov (United States)

    de Kruijff, Robin M; Wolterbeek, Hubert T; Denkova, Antonia G

    2015-01-01

    This review presents an overview of the successes and challenges currently faced in alpha radionuclide therapy. Alpha particles have an advantage in killing tumour cells as compared to beta or gamma radiation due to their short penetration depth and high linear energy transfer (LET). Touching briefly on the clinical successes of radionuclides emitting only one alpha particle, the main focus of this article lies on those alpha-emitting radionuclides with multiple alpha-emitting daughters in their decay chain. While having the advantage of longer half-lives, the recoiled daughters of radionuclides like 224Ra (radium), 223Ra, and 225Ac (actinium) can do significant damage to healthy tissue when not retained at the tumour site. Three different approaches to deal with this problem are discussed: encapsulation in a nano-carrier, fast uptake of the alpha emitting radionuclides in tumour cells, and local administration. Each approach has been shown to have its advantages and disadvantages, but when larger activities need to be used clinically, nano-carriers appear to be the most promising solution for reducing toxic effects, provided there is no accumulation in healthy tissue. PMID:26066613

  19. A Critical Review of Alpha Radionuclide Therapy—How to Deal with Recoiling Daughters?

    Science.gov (United States)

    de Kruijff, Robin M.; Wolterbeek, Hubert T.; Denkova, Antonia G.

    2015-01-01

    This review presents an overview of the successes and challenges currently faced in alpha radionuclide therapy. Alpha particles have an advantage in killing tumour cells as compared to beta or gamma radiation due to their short penetration depth and high linear energy transfer (LET). Touching briefly on the clinical successes of radionuclides emitting only one alpha particle, the main focus of this article lies on those alpha-emitting radionuclides with multiple alpha-emitting daughters in their decay chain. While having the advantage of longer half-lives, the recoiled daughters of radionuclides like 224Ra (radium), 223Ra, and 225Ac (actinium) can do significant damage to healthy tissue when not retained at the tumour site. Three different approaches to deal with this problem are discussed: encapsulation in a nano-carrier, fast uptake of the alpha emitting radionuclides in tumour cells, and local administration. Each approach has been shown to have its advantages and disadvantages, but when larger activities need to be used clinically, nano-carriers appear to be the most promising solution for reducing toxic effects, provided there is no accumulation in healthy tissue. PMID:26066613

  20. A Critical Review of Alpha Radionuclide Therapy—How to Deal with Recoiling Daughters?

    Directory of Open Access Journals (Sweden)

    Robin M. de Kruijff

    2015-06-01

    Full Text Available This review presents an overview of the successes and challenges currently faced in alpha radionuclide therapy. Alpha particles have an advantage in killing tumour cells as compared to beta or gamma radiation due to their short penetration depth and high linear energy transfer (LET. Touching briefly on the clinical successes of radionuclides emitting only one alpha particle, the main focus of this article lies on those alpha-emitting radionuclides with multiple alpha-emitting daughters in their decay chain. While having the advantage of longer half-lives, the recoiled daughters of radionuclides like 224Ra (radium, 223Ra, and 225Ac (actinium can do significant damage to healthy tissue when not retained at the tumour site. Three different approaches to deal with this problem are discussed: encapsulation in a nano-carrier, fast uptake of the alpha emitting radionuclides in tumour cells, and local administration. Each approach has been shown to have its advantages and disadvantages, but when larger activities need to be used clinically, nano-carriers appear to be the most promising solution for reducing toxic effects, provided there is no accumulation in healthy tissue.

  1. Guidelines for screening, prophylaxis and critical information prior to initiating anti-TNF-alpha treatment

    DEFF Research Database (Denmark)

    Lassen, Inge Nordgaard; Dahlerup, Jens Frederik; Belard, Erika;

    2012-01-01

    -TNF-alpha agents. Screening should take place for both active tuberculosis and latent tuberculosis. Screening must evaluate the risk of hepatitis B exposure/infection and that of other viral infections such as human immunodeficiency virus (HIV) and varicella zoster virus (VZV). The assessment should include......-rays and laboratory tests, including an interferon gamma release assay, a hepatitis B test, an HIV test and, when prior VZV infection is uncertain, a VZV antibody test. Prophylaxis: Isoniazid should be administered in cases of suspected latent TB infection. Antiviral treatment is recommended in HBs......Ag-positive patients at the start of anti-TNF-alpha treatment. Before anti-TNF-alpha therapy, vaccination with 23-valent pneumococcal vaccine is recommended, and HBV vaccination may be considered in seronegative patients. Annual vaccination against seasonal influenza is recommended. Human papilloma virus vaccination...

  2. Concurrent Supermassive Black Hole and Galazy Growth: Linking Environment and Nuclear Activity in Zeta Equals 2.23 H Alpha Emitters

    Science.gov (United States)

    Lehmer, B. D.; Lucy, A. B.; Alexander, D. M.; Best, P. N.; Geach, J. E.; Harrison, C. M.; Hornschemeier, A. E.; Matsuda, Y.; Mullaney, J. R.; Smail, Ian; Sobral, D.; Swinbank, A. M.

    2013-01-01

    We present results from an approximately equal 100 ks Chandra observation of the 2QZ Cluster 1004+00 structure at z = 2.23 (hereafter 2QZ Clus). 2QZ Clus was originally identified as an overdensity of four optically-selected QSOs at z = 2.23 within a 15 × 15 arcmin square region. Narrow-band imaging in the near-IR (within the K band) revealed that the structure contains an additional overdensity of 22 z = 2.23 H alpha-emitting galaxies (HAEs), resulting in 23 unique z = 2.23 HAEs/QSOs (22 within the Chandra field of view). Our Chandra observations reveal that three HAEs in addition to the four QSOs harbor powerfully accreting supermassive black holes (SMBHs), with 2-10 keV luminosities of approximately equal (8-60) × 10(exp 43) erg s(exp-1) and X-ray spectral slopes consistent with unobscured active galactic nucleus (AGN). Using a large comparison sample of 210 z = 2.23 HAEs in the Chandra-COSMOS field (C-COSMOS), we find suggestive evidence that the AGN fraction increases with local HAE galaxy density. The 2QZ Clus HAEs reside in a moderately overdense environment (a factor of approximately equal 2 times over the field), and after excluding optically-selected QSOs, we find that the AGN fraction is a factor of approximately equal 3.5(+3.8/ -2.2) times higher than C-COSMOS HAEs in similar environments. Using stacking analyses of the Chandra data and Herschel SPIRE observations at 250micrometers, we respectively estimate mean SMBH accretion rates ( M(BH)) and star formation rates (SFRs) for the 2QZ Clus and C-COSMOS samples. We find that the mean 2QZ Clus HAE stacked X-ray luminosity is QSO-like (L(2-10 keV) approximately equal [6-10] × 10(exp 43) erg s(exp -1)), and the implied M(BH)/SFR approximately equal (1.6-3.2) × 10(exp -3) is broadly consistent with the local M(BH)/Stellar Mass relation and z approximately equal 2 X-ray selected AGN. In contrast, the C-COSMOS HAEs are on average an order of magnitude less X-ray luminous and have M(BH)/SFR approximately

  3. Measurements of {beta} or {alpha} emitter long lived radionuclides using inductively coupled plasma mass spectrometry; Dosage a tres bas niveau de radionucleides a longue periode emetteurs {beta} ou {alpha} par spectrometrie de masse a couplage plasma inductif

    Energy Technology Data Exchange (ETDEWEB)

    Provitina, O.

    1993-10-18

    The measurement of long-lived radionuclides is highly important for characterizing nuclear wastes for their later storage. The main techniques are {alpha} spectrometry, {beta} counting and {gamma} spectrometry. The large period of these isotopes leads to low specific activity needing time consuming measurements. Moreover, the radiometric techniques are often limited by problems of interferences involving several steps of pretreatments. Among these steps, the specific extraction with crown ethers is highly selective for the separation of {sup 99}Tc, {sup 129}I and {sup 135}Cs. The radiometric techniques are here replaced by inductively coupled plasma mass spectroscopy (ICP-MS) the advantages of which are: few interferences, sensitivity which does not depend on the radiologic period as compared to radiochemistry. ICP-MS can then measure {sup 237}Np in enriched uranium matrix and reduce by a factor of 4 the sample pretreatment and the duration of the analysis usually performed by {alpha} spectrometry. Another technique, electrothermal vaporization (ETV), is consequently used. Crown ether extraction-ETV-ICP-MS is employed for measuring the long lived radionuclides {sup 99}Tc and {sup 129}I. The conditions of the extraction and the parameters of the ETV and the ICP-MS are studied and optimized. The methods optimized (extraction, electrothermal vaporization) are validated in the case of {sup 99}Tc, in real samples. The spike method is required to quantify technetium, the quantification with calibration leading to bad results. The results obtained are in good agreement with the expected values. Extraction of technetium on anionic resin and its measurement by the spike method with pneumatic nebulization-ICP-MS is also performed on other samples. Measured values are also in agreement with expected values, but the method of extraction is more time consuming (half a day) than the extraction with crown ether (one hour). (author). 54 figs., 38 tabs.

  4. Multibunch Emittance Preservation in CLIC

    CERN Document Server

    Guignard, Gilbert

    1996-01-01

    In high-frequency linacs, where the wakefields are strong, the stability of a train of bunches is critical. The beam break-up due to long range wakefields induces a decoherence of the bunch oscillations and a consequent blow-up of the effective betatron emittances of the whole train. Since the Compact Linear Collider (CLIC) study now includes several bunches per pulse, it is important to analyse numerically and theoretically this emittance blow-up. possibilities of controlling the beam break-up without upsetting the single bunch stability have been considered: first a multibunch generalization of the BNS damping principle, secondly an attenuation of the long-range fields, and thirdly an increase of the focusing in order to overconstrain the beam. Simulation codes have been written for both checking the theoretical predictions and investigating the requirements associated with a possible application to the main linac. Animated graphics make it possible to get a didactic display of the multibunch instability.

  5. Scaling law and critical exponent for {alpha}{sub 0} at the 3D Anderson transition

    Energy Technology Data Exchange (ETDEWEB)

    Slevin, K. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Rodriguez, A.; Roemer, R.A. [Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL (United Kingdom); Vasquez, L.J.

    2009-12-15

    We use high-precision, large system-size wave function data to analyse the scaling properties of the multifractal spectra around the disorder-induced three-dimensional Anderson transition in order to extract the critical exponents of the transition. Using a previously suggested scaling law, we find that the critical exponent {nu} is significantly larger than suggested by previous results. We speculate that this discrepancy is due to the use of an oversimplified scaling relation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  6. Hypoxia inducible factor 1-alpha (HIF-1 alpha is induced during reperfusion after renal ischemia and is critical for proximal tubule cell survival.

    Directory of Open Access Journals (Sweden)

    Elisa Conde

    Full Text Available Acute tubular necrosis (ATN caused by ischemia/reperfusion (I/R during renal transplantation delays allograft function. Identification of factors that mediate protection and/or epithelium recovery could help to improve graft outcome. We studied the expression, regulation and role of hypoxia inducible factor 1-alpha (HIF-1 α, using in vitro and in vivo experimental models of I/R as well as human post-transplant renal biopsies. We found that HIF-1 α is stabilized in proximal tubule cells during ischemia and unexpectedly in late reperfusion, when oxygen tension is normal. Both inductions lead to gene expression in vitro and in vivo. In vitro interference of HIF-1 α promoted cell death and in vivo interference exacerbated tissue damage and renal dysfunction. In pos-transplant human biopsies, HIF-1 α was expressed only in proximal tubules which exhibited normal renal structure with a significant negative correlation with ATN grade. In summary, using experimental models and human biopsies, we identified a novel HIF-1 α induction during reperfusion with a potential critical role in renal transplant.

  7. Accuracy of Alpha Amylase in Diagnosing Microaspiration in Intubated Critically-Ill Patients

    OpenAIRE

    Florent Dewavrin; Farid Zerimech; Alexandre Boyer; Patrice Maboudou; Malika Balduyck; Alain Duhamel; Saad Nseir

    2014-01-01

    OBJECTIVES: Amylase concentration in respiratory secretions was reported to be a potentially useful marker for aspiration and pneumonia. The aim of this study was to determine accuracy of α-amylase in diagnosing microaspiration in critically ill patients. METHODS: Retrospective analysis of prospectively collected data collected in a medical ICU. All patients requiring mechanical ventilation for at least 48 h, and included in a previous randomized controlled trial were eligible for this study,...

  8. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  9. The neuropeptide alpha-melanocyte-stimulating hormone is critically involved in the development of cytotoxic CD8+ T cells in mice and humans.

    Directory of Open Access Journals (Sweden)

    Karin Loser

    Full Text Available BACKGROUND: The neuropeptide alpha-melanocyte-stimulating hormone is well known as a mediator of skin pigmentation. More recently, it has been shown that alpha-melanocyte-stimulating hormone also plays pivotal roles in energy homeostasis, sexual function, and inflammation or immunomodulation. Alpha-melanocyte-stimulating hormone exerts its antiinflammatory and immunomodulatory effects by binding to the melanocortin-1 receptor, and since T cells are important effectors during immune responses, we investigated the effects of alpha-melanocyte-stimulating hormone on T cell function. METHODOLOGY/PRINCIPAL FINDINGS: T cells were treated with alpha-melanocyte-stimulating hormone, and subsequently, their phenotype and function was analyzed in a contact allergy as well as a melanoma model. Furthermore, the relevance of alpha-melanocyte-stimulating hormone-mediated signaling for the induction of cytotoxicity was assessed in CD8(+ T cells from melanoma patients with functional and nonfunctional melanocortin-1 receptors. Here we demonstrate that the melanocortin-1 receptor is expressed by murine as well as human CD8(+ T cells, and we furthermore show that alpha-melanocyte-stimulating hormone/melanocortin-1 receptor-mediated signaling is critical for the induction of cytotoxicity in human and murine CD8(+ T cells. Upon adoptive transfer, alpha-melanocyte-stimulating hormone-treated murine CD8(+ T cells significantly reduced contact allergy responses in recipient mice. Additionally, the presented data indicate that alpha-melanocyte-stimulating hormone via signaling through a functional melanocortin-1 receptor augmented antitumoral immunity by up-regulating the expression of cytotoxic genes and enhancing the cytolytic activity in tumor-specific CD8(+ T cells. CONCLUSIONS/SIGNIFICANCE: Together, these results point to an important role of alpha-melanocyte-stimulating hormone in MHC class I-restricted cytotoxicity. Therefore, treatment of contact allergies or

  10. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    BACKGROUND. Beta emitters, such as 90Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding. AIM. To discuss practical precautions for handling beta emitters...... on the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure....

  11. Morphometry for alpha particle hits of critical targets in the lungs. Final technical report

    International Nuclear Information System (INIS)

    The objective of this study is to provide detailed data on the number, location and type of critical target cells in the airspaces and to use these data in order to make risk assessments of the health effects of radon and radon progeny in the lungs. This will be done by quantitative morphometric study of the distribution of the various cell types and mucous lining layers in the lungs. The results provide anatomically correct models for dosimetry in the rate and human airways which significantly improve the ability to do risk assessment for radon exposures by providing quantitative data for specific cell types and provide a basis for mechanism based comparison between data available in animal exposures and human epidemiology

  12. Morphometry for alpha particle hits of critical targets in the lungs. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, R.R.

    1998-11-01

    The objective of this study is to provide detailed data on the number, location and type of critical target cells in the airspaces and to use these data in order to make risk assessments of the health effects of radon and radon progeny in the lungs. This will be done by quantitative morphometric study of the distribution of the various cell types and mucous lining layers in the lungs. The results provide anatomically correct models for dosimetry in the rate and human airways which significantly improve the ability to do risk assessment for radon exposures by providing quantitative data for specific cell types and provide a basis for mechanism based comparison between data available in animal exposures and human epidemiology.

  13. Delineation of interfaces on human alpha-defensins critical for human adenovirus and human papillomavirus inhibition.

    Directory of Open Access Journals (Sweden)

    Victoria R Tenge

    2014-09-01

    Full Text Available Human α-defensins are potent anti-microbial peptides with the ability to neutralize bacterial and viral targets. Single alanine mutagenesis has been used to identify determinants of anti-bacterial activity and binding to bacterial proteins such as anthrax lethal factor. Similar analyses of α-defensin interactions with non-enveloped viruses are limited. We used a comprehensive set of human α-defensin 5 (HD5 and human neutrophil peptide 1 (HNP1 alanine scan mutants in a combination of binding and neutralization assays with human adenovirus (AdV and human papillomavirus (HPV. We have identified a core of critical hydrophobic residues that are common determinants for all of the virus-defensin interactions that were analyzed, while specificity in viral recognition is conferred by specific surface-exposed charged residues. The hydrophobic residues serve multiple roles in maintaining the tertiary and quaternary structure of the defensins as well as forming an interface for virus binding. Many of the important solvent-exposed residues of HD5 group together to form a critical surface. However, a single discrete binding face was not identified for HNP1. In lieu of whole AdV, we used a recombinant capsid subunit comprised of penton base and fiber in quantitative binding studies and determined that the anti-viral potency of HD5 was a function of stoichiometry rather than affinity. Our studies support a mechanism in which α-defensins depend on hydrophobic and charge-charge interactions to bind at high copy number to these non-enveloped viruses to neutralize infection and provide insight into properties that guide α-defensin anti-viral activity.

  14. PENCIL LEAD FIELD EMITTER

    OpenAIRE

    Khairnar, R.; Joag, D.

    1989-01-01

    Field electron emission from 2H and HB grades of pencil lead has been studied. The pencil lead field emitter is found to obey the Fowler-Nordheim characteristics. The emission current fluctuations are found to increase with the residual gas pressure and the emission current. The current density of the order of 106 amp/cm2 could be drawn from these emitters. The emission stability over the operation of six hours has been found to be reasonably good. The field ion microscopy of the 2H and HB gr...

  15. RFI emitter location techniques

    Science.gov (United States)

    Rao, B. L. J.

    1973-01-01

    The possibility is discussed of using Doppler techniques for determining the location of ground based emitters causing radio frequency interference with low orbiting satellites. An error analysis indicates that it is possible to find the emitter location within an error range of 2 n.mi. The parameters which determine the required satellite receiver characteristic are discussed briefly along with the non-real time signal processing which may by used in obtaining the Doppler curve. Finally, the required characteristics of the satellite antenna are analyzed.

  16. The estrogen receptor alpha nuclear localization sequence is critical for fulvestrant-induced degradation of the receptor.

    Science.gov (United States)

    Casa, Angelo J; Hochbaum, Daniel; Sreekumar, Sreeja; Oesterreich, Steffi; Lee, Adrian V

    2015-11-01

    Fulvestrant, a selective estrogen receptor down-regulator (SERD) is a pure competitive antagonist of estrogen receptor alpha (ERα). Fulvestrant binds ERα and reduces the receptor's half-life by increasing protein turnover, however, its mechanism of action is not fully understood. In this study, we show that removal of the ERα nuclear localization sequence (ERΔNLS) resulted in a predominantly cytoplasmic ERα that was degraded in response to 17-β-estradiol (E2) but was resistant to degradation by fulvestrant. ERΔNLS bound the ligands and exhibited receptor interaction similar to ERα, indicating that the lack of degradation was not due to disruption of these processes. Forcing ERΔNLS into the nucleus with a heterologous SV40-NLS did not restore degradation, suggesting that the NLS domain itself, and not merely receptor localization, is critical for fulvestrant-induced ERα degradation. Indeed, cloning of the endogenous ERα NLS onto the N-terminus of ERΔNLS significantly restored both its nuclear localization and turnover in response to fulvestrant. Moreover, mutation of the sumoylation targets K266 and K268 within the NLS impaired fulvestrant-induced ERα degradation. In conclusion, our study provides evidence for the unique role of the ERα NLS in fulvestrant-induced degradation of the receptor.

  17. Alpha voltaic batteries and methods thereof

    Science.gov (United States)

    Raffaelle, Ryne P. (Inventor); Jenkins, Phillip (Inventor); Wilt, David (Inventor); Scheiman, David (Inventor); Chubb, Donald (Inventor); Castro, Stephanie (Inventor)

    2011-01-01

    An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material.

  18. Low-emittance Storage Rings

    CERN Document Server

    Wolski, A

    2014-01-01

    The effects of synchrotron radiation on particle motion in storage rings are discussed. In the absence of radiation, particle motion is symplectic, and the beam emittances are conserved. The inclusion of radiation effects in a classical approximation leads to emittance damping: expressions for the damping times are derived. Then, it is shown that quantum radiation effects lead to excitation of the beam emittances. General expressions for the equilibrium longitudinal and horizontal (natural) emittances are derived. The impact of lattice design on the natural emittance is discussed, with particular attention to the special cases of FODO-, achromat- and theoretical-minimum-emittance-style lattices. Finally, the effects of betatron coupling and vertical dispersion (generated by magnet alignment and lattice tuning errors) on the vertical emittance are considered.

  19. Directional Thermal Emitter Simulation

    OpenAIRE

    Dhaka, Shailja; Sakr, Enas Said; Bermel, Peter

    2015-01-01

    The development of renewable energy sources has attracted increasing interest because of negative externalities associated with fossil fuel use. Thermophotovoltaics is a promising technology, in which a thermal emitter radiates photons which are directly converted into electricity using a photovoltaic diode. However, blackbody emission includes a broad range of wavelengths, but only higher energy photons can be converted into electricity. Thus, tailoring the selectivity of thermal emission is...

  20. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  1. Measurement of emittance and emittance reduction in MICE

    Energy Technology Data Exchange (ETDEWEB)

    Palladino, Vittorio [Univ. and Istituto Nazionale di Fisica Nucleare - INFN, Sezione di Napoli, Complesso Universitario di Monte Sant' Angelo, via Cintia, I-80126, Napoli (Italy); Verguilov, Vassil [Departement de physique nucleaire et corpusculaire - DPNC, Geneva University, 24, Quai Ernest Ansermet, 1211 Geneve 4 (Switzerland)

    2010-07-01

    MICE is building at RAL a muon beam with tunable emittance and an array of detectors capable to measure the emittance of the beam before and after any ionization cooling device that will be designed in the future. This talk will present the details of the measurements of beam emittance and of emittance reduction, the tracking and particle identification instrumentation used for this purpose, the physical observables and the techniques being prepared to provide convincing evidence of effective ionisation cooling. After the measurement of the transverse cooling performances of the cooling cell designed in early feasibility studies of a neutrino factory, the MICE beam and emittance measurement devices will remain as a facility for the study of new candidate cooling cell prototypes, including exchange between transverse and longitudinal emittance cooling. Some of those emerging options will also be briefly mentioned. (author)

  2. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    Science.gov (United States)

    Wang, Daojing; Yang, Peidong; Kim, Woong; Fan, Rong

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  3. Report of a Technical Meeting on ''Alpha emitting radionuclides and radiopharmaceuticals for therapy''

    International Nuclear Information System (INIS)

    Considering the high potential of α-emitters for future development of radionuclide therapy, the International Atomic Energy Agency (IAEA) organized a Technical Meeting on ‘Alpha Emitting Radionuclides and Radiopharmaceuticals for Therapy’, from June 24 to 28, 2013, at IAEA Headquarters in Vienna with the purpose of gathering eminent Experts in the field and discuss with them the status and future perspectives of the field. Sixteen Experts and two External Observers from ten different countries, and four IAEA Technical Officers attended this meeting. Outstanding lectures have been presented covering all relevant aspects of α-therapy, which were followed by extensive discussions and analysis. Selected arguments encompassed production methods and availability of alpha-emitting radionuclides, labelling chemistry of alpha-emittting radioelements, design and development of target-specific radiopharmaceuticals, physical principles of alpha-particle dosimetry and advanced dosimetric models, biological effects of alpha radiation at the cellular level, on-going preclinical and clinical studies with new radiopharmaceuticals, results of clinical trials on the use of radium-223 chloride solutions for the treatment of metastatic bone cancer. The broad scientific background of invited components of the Experts’ panel conferred a strong interdisciplinary trait to the overall discussion and stimulated a critical analysis of this emerging unexplored field. Results of this comprehensive overview on alpha therapy, including recommendations to the Agency on suitable initiatives that may help to promote and spread the knowledge to Members States on this emerging therapeutic modality, are summarized in the present Report

  4. Emittance growth in rf linacs

    International Nuclear Information System (INIS)

    As the space-charge limit is approached, the current that can be accelerated in an rf linac and the output emittance that can be expected are discussed. The role of the envelope equations to estimate limits is outlined. The results of numerical experiments to explore general properties of emittance growth are given

  5. Localization of narrowband single photon emitters in nanodiamonds

    CERN Document Server

    Bray, Kerem; Elbadawi, Christopher; Fischer, Martin; Schreck, Matthias; Shimoni, Olga; Lobo, Charlene; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bio-imaging. However, current understanding of the origin of these emitters is extremely limited. In this work we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond, and are directly relevant to fabrication of novel quantum optics devices and sensors.

  6. Hole emitter whispering galleries of photonic quantum ring

    CERN Document Server

    Kwon, O; an, S J; Kim, D K; Lee, S E; Bae, J; Yoon, J H; Park, B H; Kim, J; Ahn, J; Park, S; Kwon, Odae

    2005-01-01

    We report on the first observation of hole whispering gallery lasers from semiconductor microcavities with three dimensional optical confinement, with thresholds potentially reducible to micro-to-nano ampere regimes according to a quadratic size-dependent reduction, due to ideal quantum wire properties of the naturally formed photonic quantum rings before imminent recombination in a dynamic steady state fashion. If the device size grows over a critical diameter, the quantum ring whispering gallery then begins to disappear. However, cooperative small hole arrays like 256x256 quantum ring emitters avoid the criticality and open a possibility of constructing practical dense electro-pumped micro-to-nano watt emitter arrays, amenable to mega-to-giga ring emitter chip development via present fabrication techniques.

  7. Beam emittance measurements in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Zelenski,A.; Bazilevsky, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y.; Morozov, B.; Nemesure, S.; Russo, t.; Steski, D.; Sivertz, M.

    2009-05-04

    The RHIC proton polarimeters can operate in scanning mode, giving polarization profiles and transverse beam intensity profile (beam emittance) measurements. The polarimeters function as wire scanners, providing a very good signal/noise ratio and high counting rate. This allows accurate bunch-by-bunch emittance measurements during fast target sweeps (<1 s) through the beam. Very thin carbon strip targets make these measurements practically non-destructive. Bunch by bunch emittance measurements are a powerful tool for machine set-up; in RHIC, individual proton beam transverse emittances can only be measured by CNI polarimeter scans. We discuss the consistency of these measurements with Ionization Profile Monitors (IPMs) and vernier scan luminosity measurements. Absolute accuracy limitations and cross-calibration of different techniques are also discussed.

  8. Diamondoid monolayers as electron emitters

    Science.gov (United States)

    Yang, Wanli; Fabbri, Jason D.; Melosh, Nicholas A.; Hussain, Zahid; Shen, Zhi-Xun

    2012-04-10

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  9. Visible Spectrum Incandescent Selective Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Sonsight Inc.

    2004-04-30

    The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination

  10. Sets of Reports and Articles Regarding Cement Wastes Forms Containing Alpha Emitters that are Potentially Useful for Development of Russian Federation Waste Treatment Processes for Solidification of Weapons Plutonium MOX Fuel Fabrication Wastes for

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, L J

    2003-06-12

    This is a set of nine reports and articles that were kindly provided by Dr. Christine A. Langton from the Savannah River Site (SRS) to L. J. Jardine LLNL in June 2003. The reports discuss cement waste forms and primarily focus on gas generation in cement waste forms from alpha particle decays. However other items such as various cement compositions, cement product performance test results and some cement process parameters are also included. This set of documents was put into this Lawrence Livermore National Laboratory (LLNL) releasable report for the sole purpose to provide a set of documents to Russian technical experts now beginning to study cement waste treatment processes for wastes from an excess weapons plutonium MOX fuel fabrication facility. The intent is to provide these reports for use at a US RF Experts Technical Meeting on: the Management of Wastes from MOX Fuel Fabrication Facilities, in Moscow July 9-11, 2003. The Russian experts should find these reports to be very useful for their technical and economic feasibility studies and the supporting R&D activities required to develop acceptable waste treatment processes for use in Russia as part of the ongoing Joint US RF Plutonium Disposition Activities.

  11. $\\mathbf{\\alpha}$-induced reaction cross sections in the mass range $\\mathbf{A \\approx 20 - 50}$: a critical review

    CERN Document Server

    Mohr, Peter

    2016-01-01

    In a recent review it was shown that the cross sections of $\\alpha$-induced reactions in the $A \\approx 20 - 50$ mass range follow a general and smooth trend in most cases. For comparison of cross sections of different targets at various energies the method of reduced cross sections $\\sigma_{\\rm{red}}$ and reduced energies $E_{\\rm{red}}$ was used. Four outliers were identified: $^{36}$Ar and $^{40}$Ar with unusally small cross sections and $^{23}$Na and $^{33}$S with unusually large cross sections. New data for $^{23}$Na were presented at this NPA-7 conference; contrary to the previous data, these new data fit into the general systematics. In addition, a relation between the most effective energy $E_0$ for astrophysical reaction rates (the so-called Gamow window) and the reduced energy $E_{\\rm{red}}$ is presented.

  12. Emittance measurements on ETA and ATA

    International Nuclear Information System (INIS)

    Emittance measurements on beams produced by the ETA and ATA accelerators are discussed. Emittance and brightness are defined. The significance of emittance for a beam in an accelerator and in gas is discussed. Various measurement techniques and results are presented and contrasted. Implicit calculations of emittance are also reported. Finally, the measurement of the time variation of emittance is discussed and the techniques to be used on the upcoming ATA experiments are outlined

  13. Targeted alpha-radionuclide therapy of functionally critically located gliomas with 213Bi-DOTA-[Thi8,Met(O2)11]-substance P: a pilot trial

    International Nuclear Information System (INIS)

    Functionally critically located gliomas represent a challenging subgroup of intrinsic brain neoplasms. Standard therapeutic recommendations often cannot be applied, because radical treatment and preservation of neurological function are contrary goals. The successful targeting of gliomas with locally injected beta radiation-emitting 90Y-DOTAGA-substance P has been shown previously. However, in critically located tumours, the mean tissue range of 5 mm of 90Y may seriously damage adjacent brain areas. In contrast, the alpha radiation-emitting radionuclide 213Bi with a mean tissue range of 81 μm may have a more favourable toxicity profile. Therefore, we evaluated locally injected 213Bi-DOTA-substance P in patients with critically located gliomas as the primary therapeutic modality. In a pilot study, we included five patients with critically located gliomas (WHO grades II-IV). After diagnosis by biopsy, 213Bi-DOTA-substance P was locally injected, followed by serial SPECT/CT and MR imaging and blood sampling. Besides feasibility and toxicity, the functional outcome was evaluated. Targeted radiopeptide therapy using 213Bi-DOTA-substance P was feasible and tolerated without additional neurological deficit. No local or systemic toxicity was observed. 213Bi-DOTA-substance P showed high retention at the target site. MR imaging was suggestive of radiation-induced necrosis and demarcation of the tumours, which was validated by subsequent resection. This study provides proof of concept that targeted local radiotherapy using 213Bi-DOTA-substance P is feasible and may represent an innovative and effective treatment for critically located gliomas. Primarily non-operable gliomas may become resectable with this treatment, thereby possibly improving the prognosis. (orig.)

  14. Critical appraisal of the use of alpha lipoic acid (thioctic acid in the treatment of symptomatic diabetic polyneuropathy

    Directory of Open Access Journals (Sweden)

    McIlduff CE

    2011-09-01

    Full Text Available Courtney E McIlduff, Seward B RutkoveDepartment of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USABackground: The most common of the neuropathies associated with diabetes mellitus, diabetic sensorimotor polyneuropathy (DSPN is a syndrome of diffuse, length-dependent, symmetric nerve dysfunction. The condition is linked with substantial morbidity, frequent healthcare utilization, and compromised quality of life due to related discomfort. Correspondingly, antidepressants, anticonvulsants, and opioids are regularly prescribed with the goal of pain control. However, the agents rarely provide complete pain relief and fail to address progression of the disorder. Whereas strict blood glucose control can slow the onset and worsening of DSPN, near-normoglycemia is not easily attainable. Evidence implicating oxidative processes in the pathogenesis of DSPN offers one potentially important therapeutic avenue. Due to its properties as a potent antioxidant, alpha lipoic acid (ALA could mitigate the development of DSPN and attenuate resultant symptoms and signs. Approved for treatment of DSPN in Germany, the agent is not more widely used due to uncertainty about its efficacy and reported adverse effects. Here we review the effectiveness and tolerability of ALA in the treatment of symptomatic DSPN.Methods: The MEDLINE, EMBASE, and Cochrane Library databases were searched for English-language literature on the topic. Randomized, blinded studies comparing parenteral and oral ALA with placebo in the treatment of peripheral neuropathy in diabetic adults were selected. Analysis included studies with a level of evidence of at least 2b.Results: The current appraisal summarizes data from 1160 participants in the ALADIN, SYDNEY, ORPIL, SYDNEY 2, and ALADIN III trials. In four of the studies, ALA provided significant improvement in manifestations of DSPN.Conclusion: Treatment with ALA 600 mg iv daily for 3 weeks represents a well-tolerated and effective

  15. Qualitative and quantitative analysis of beta emitters in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hamzah, Zaini bin

    1983-01-01

    A beta spectrometer, consisting of a liquid scintillation counter, coupled to a programmable multichannel analyser was used to achieve the objective of detecting and measuring beta activity in low level aqueous environmental solution as well as identifying the radioisotopes present. Aqueous solutions of standard beta emitters, covering a range of energies between 18.6 KeV and 3550 KeV, were used to develop computer methods for analysis. The effects of pH, acids, bases, buffers, and salts on the stability of the mixture and on the detection efficiency of the radioisotopes, were investigated. It was found that temperature changes, beyond the operating temperature range, could result in severe errors. Application of the Cherenkov counting technique for beta emitters, gives extra data to support the main results. For the analysis of environmental solutions, which may contain a variety of radioisotopes, the system was used to obtain spectra of alpha emitters, beta emitters with internal conversion and Cherenkov radiation. Synthetic mixtures of tritium and carbon-14 of activity ratios between 8:1 and 1:8 were used to investigate the problems of multielement spectral analysis.

  16. Combustion powered thermophotovoltaic emitter system

    Energy Technology Data Exchange (ETDEWEB)

    McHenry, R.S. [Naval Academy, Annapolis, MD (United States). Naval Architecture, Ocean and Marine Engineering

    1995-07-01

    The US Naval Academy (USNA) has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The final apparatus was to be portable, completely self contained, and was to incorporate cycle efficiency optimization such as exhaust stream recuperation. Through computer modeling and prototype experimentation, a methane fueled emitter system was designed from structural ceramic materials to fulfill the high temperature requirements necessary for high system efficiency. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design.

  17. Green Pea Galaxies Reveal Secrets of Ly$\\alpha$ Escape

    CERN Document Server

    Yang, Huan; Gronke, Max; Rhoads, James E; Jaskot, Anne; Zheng, Zhenya; Dijkstra, Mark

    2015-01-01

    Star-formation in galaxies generates a lot of Ly$\\alpha$ photons. Understanding the escape of Ly$\\alpha$ photons from galaxies is a key issue in studying high redshift galaxies and probing cosmic reionization with Ly$\\alpha$. To understand Ly$\\alpha$ escape, it is valuable to study analogs of high redshift Ly$\\alpha$ emitters in nearby universe. However, most nearby analogs have too small a Ly$\\alpha$ equivalent width and escape fraction compared to high redshift Ly$\\alpha$ emitters. One different group of nearby analogs are "Green Pea" galaxies, selected by their high equivalent width optical emission lines. Here we show that Green Pea galaxies have strong Ly$\\alpha$ emission lines and high Ly$\\alpha$ escape fraction (see also Henry et al. 2015), providing an opportunity to solve Ly$\\alpha$ escape problem. Green Peas have a Ly$\\alpha$ equivalent width distribution similar to high redshift Ly$\\alpha$ emitters. The Ly$\\alpha$ escape fraction correlates with many quantities of Ly$\\alpha$ profile, especially the...

  18. Intraperitoneal alpha-radioimmunotherapy in mice using different specific activities

    DEFF Research Database (Denmark)

    Elgqvist, Jörgen; Andersson, Håkan; Haglund, Elin;

    2009-01-01

    The aim of this study was to investigate the therapeutic efficacy of the alpha-radioimmunotherapy of ovarian cancer in mice, using different specific activities. This study was performed by using the monoclonal antibody, MX35 F(ab')(2), labeled with the alpha-particle-emitter, 211At.......The aim of this study was to investigate the therapeutic efficacy of the alpha-radioimmunotherapy of ovarian cancer in mice, using different specific activities. This study was performed by using the monoclonal antibody, MX35 F(ab')(2), labeled with the alpha-particle-emitter, 211At....

  19. Ultra Low Emittance Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson,J.

    2008-06-23

    This paper outlines the special issues for reaching sub-nm emittance in a storage ring. Effects of damping wigglers, intra-beam scattering and lifetime issues, dynamic aperture optimization, control of optics, and their interrelations are covered in some detail. The unique choices for the NSLS-II are given as one example.

  20. Radiation dosimetry in radiotherapy with internal emitters

    Energy Technology Data Exchange (ETDEWEB)

    Stabin, Michael G. [Oak Ridge Inst. for Science and Education, TN (United States)

    1997-12-31

    Full text. Radiation dosimetry radionuclides are currently being labeled to various biological agents used in internal emitter radiotherapy. This talk will review the various technologies and types of radiolabel in current use, with focus on the characterization of the radiation dose to the various important tissues of the body. Methods for obtaining data, developing kinetic models, and calculating radiation doses will be reviewed. Monoclonal antibodies are currently being labeled with both alpha and beta emitting radionuclides in attempts to find effective agents against cancer. Several radionuclides are also being used as bone pain palliation agents. These agents must be studied in clinical trials to determine the biokinetics and radiation dosimetry prior to approval for general use. In such studies, it is important to ensure the collection of the appropriate kinds of data and to collect the data at appropriate time intervals. The uptake and retention of activity in all significant source organs and in excreta be measured periodically (with at least 2 data points phase of uptake or clearance). Then, correct dosimetry methods must be applied - the best available methods for characterizing the radionuclide kinetic and for estimating the dosimetry in the various organs of the body especially the marrow, should be used. Attempts are also under way to develop methods for estimating true patient-specific dosimetry. Cellular and animal studies are also. Valuable in evaluating the efficacy of the agents in shrinking or eliminating tumors; some results from such studies will also be discussed. The estimation of radiation doses to patients in therapy with internal emitters involves several complex phases of analysis. Careful attention to detail and the use of the best available methods are essential to the protection of the patient and a successful outcome

  1. Oxidation and emittance of superalloys in heat shield applications

    Science.gov (United States)

    Wiedemann, K. E.; Clark, R. K.; Unnam, J.

    1986-01-01

    Recently developed superalloys that form alumina coatings have a high potential for heat shield applications for advanced aerospace vehicles at temperatures above 1095C. Both INCOLOY alloy MA 956 (of the Inco Alloys International, Inc.), an iron-base oxide-dispersion-strengthened alloy, and CABOT alloy No. 214 (of the Cabot Corporation), an alumina-forming nickel-chromium alloy, have good oxidation resistance and good elevated temperature strength. The oxidation resistance of both alloys has been attributed to the formation of a thin alumina layer (alpha-Al2O3) at the surface. Emittance and oxidation data were obtained for simulated Space Shuttle reentry conditions using a hypersonic arc-heated wind tunnel. The surface oxides and substrate alloys were characterized using X-ray diffraction and scanning and transmission electron microscopy with an energy-dispersive X-ray analysis unit. The mass loss and emittance characteristics of the two alloys are discussed.

  2. Alpha Schottky junction energy source

    Science.gov (United States)

    Litz, Marc S.; Fan, Zhaoyang; Carroll, James J.; Bayne, Stephen

    2012-06-01

    Isotope batteries offer solutions for long-lived low-power sensor requirements. Alpha emitting isotopes have energy per decay 103 times that of beta emitters. Alpha particles are absorbed within 20 μm of most materials reducing shielding mitigation. However, damage to materials from the alphas limits their practical use. A Schottky Barrier Diode (SBD) geometry is considered with an alpha emitting contact-layer on a diamond-like crystal semiconductor region. The radiation tolerance of diamond, the safety of alpha particles, combined with the internal field of the SBD is expected to generate current useful for low-power electronic devices over decades. Device design parameters and calculations of the expected current are described.

  3. Properties of Lya Emitters Around the Radio Galaxy MRC 0316-257

    Energy Technology Data Exchange (ETDEWEB)

    Venemans, B; Rottgering, H; Miley, G; Kurk, J; De Breuck, C; van Breugel, W; Carilli, C; Ford, H; Heckman, T; Pentericci, L; McCarthy, P

    2004-08-12

    Observations of the radio galaxy MRC 0316-257 at z = 3.13 and the surrounding field are presented. Using narrow- and broad-band imaging obtained with the VLT*, 92 candidate Ly{alpha} emitters with a rest-frame equivalent width of > 15 AngstromS were selected in a {approx} 7{prime} x 7{prime} field around the radio galaxy. Spectroscopy of 40 candidate emitters resulted in the discovery of 33 emission line galaxies of which 31 are Ly{alpha} emitters with redshifts similar to that of the radio galaxy, while the remaining two galaxies turned out to be [{omicron} II] emitters. The Ly{alpha} profiles had widths (FWHM) corresponding to 120-800 kms{sup -1},with a median of 260 kms{sup -1}. Where the signal-to-noise spectra was large enough, the Ly{alpha} profiles are found to be asymmetric, with apparent absorption troughs blueward of the profile peaks, indicative of absorption along the line of sight of an {Eta}{Iota} mass of 1-5000 {mu}{circle_dot}. Besides that of the radio galaxy and one of the emitters that is an QSO, the continuum of the emitters is faint, with luminosities ranging from 1.3 L{sub *} to < 0.03 L{sub *}.The colors of the confirmed emitters are, on average, very blue. The median UV continuum slope is {beta}=-1.65, bluer than the average slope of LBGs with Ly{alpha} emitters is 2.6 {Mu}{circle_dot}{sup -1} as measured by the Ly{alpha} emission line or < 3.9 {Mu}{circle_dot}{sup -1} as measured by the UV continuum. The properties of the Ly{alpha} galaxies (faint, blue and small) are consistent with young star forming galaxies which are nearly dust free. The density of Ly{alpha} emitting galaxies in the field around MRC 0316-257 is a factor of 3.3{sup +0.5}{sub -0.4} larger compared with the density of Ly{alpha} emitters at that redshift. The velocity distribution of the spectroscopically confirmed emitters has a dispersion of 640 km s{sup -1}, corresponding to a FWHM of 1510 km s{sup -1}, which is substantially smaller than the width of the narrow

  4. Elf-1 and Stat5 bind to a critical element in a new enhancer of the human interleukin-2 receptor alpha gene

    OpenAIRE

    Lécine, P; Algarté, M; Rameil, P; Beadling, C; Bucher, P.; Nabholz, M; Imbert, J

    1997-01-01

    The interleukin 2 receptor alpha-chain (IL-2R alpha) gene is a key regulator of lymphocyte proliferation. IL-2R alpha is rapidly and potently induced in T cells in response to mitogenic stimuli. Interleukin 2 (IL-2) stimulates IL-2R alpha. transcription, thereby amplifying expression of its own high-affinity receptor. IL-2R alpha transcription is at least in part controlled by two positive regulatory regions, PRRI and PRRII. PRRI is an inducible proximal enhancer, located between nucleotides ...

  5. Electric field distribution of electron emitter surfaces

    Science.gov (United States)

    Tagawa, M.; Takenobu, S.; Ohmae, N.; Umeno, M.

    1987-03-01

    The electric field distribution of a tungsten field emitter surface and a LaB6 thermionic emitter surface has been studied. The computer simulation of electric field distribution on the emitter surface was carried out with a charge simulation method. The electric field distribution of the LaB6 thermionic emitter was experimentally evaluated by the Schottky plot. Two independent equations are necessary for obtaining local electric field and work function; the Fowler-Nordheim equation and the equation of total energy distribution of emitted electron being used to evaluate the electric field distribution of the tungsten field emitter. The experimental results agreed with the computer simulation.

  6. Deep rest-frame far-UV spectroscopy of the giant Lyman α emitter 'Himiko'

    DEFF Research Database (Denmark)

    Zabl, J.; Nørgaard-Nielsen, Hans Ulrik; Fynbo, J. P. U.;

    2015-01-01

    We present deep 10 h VLT/XSHOOTER spectroscopy for an extraordinarily luminous and extended Ly alpha emitter at z = 6.595 referred to asHimiko and first discussed by Ouchi et al., with the purpose of constraining the mechanisms powering its strong emission. Complementary to the spectrum, we discuss...

  7. Beam emittance measurements at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Manfred; Eddy, Nathan; Hu, Martin; Scarpine, Victor; Syphers, Mike; Tassotto, Gianni; Thurman-Keup, Randy; Yang, Ming-Jen; Zagel, James; /Fermilab

    2008-01-01

    We give short overview of various beam emittance measurement methods, currently applied at different machine locations for the Run II collider physics program at Fermilab. All these methods are based on beam profile measurements, and we give some examples of the related instrumentation techniques. At the end we introduce a multi-megawatt proton source project, currently under investigation at Fermilab, with respect to the beam instrumentation challenges.

  8. Hypoxia-inducible factor-1 alpha, in association with inflammation, angiogenesis and MYC, is a critical prognostic factor in patients with HCC after surgery

    Directory of Open Access Journals (Sweden)

    Zhou Jian

    2009-12-01

    Full Text Available Abstract Background Despite well-studied tumor hypoxia in laboratory, little is known about the association with other pathophysiological events in the clinical view. We investigated the prognostic value of hypoxia-inducible factor-1 alpha (HIF-1alpha in hepatocellular carcinoma (HCC, and its correlations with inflammation, angiogenesis and MYC oncogene. Methods In a random series of 110 HCC patients, the mRNA of HIF-1alpha, inflammation related factors (COX-2, MMP7 and MMP9, angiogenesis related factors (VEGF and PDGFRA and MYC in tumor tissue were detected by real-time RT-PCR and HIF-1alpha protein was assessed by immunohistochemistry. The correlations between HIF-1alpha mRNA and the factors mentioned previously, the relationship between HIF-1alpha and clinicopathologic features, and the prognostic value were analyzed. Results The expression of both HIF-1alpha mRNA and protein in HCC were independent prognostic factors for overall survival (OS (P = 0.012 and P = 0.021, respectively and disease-free survival (DFS (P = 0.004 and P = 0.007, respectively as well. Besides, the high expression of HIF-1alpha mRNA and protein proposed an advanced BCLC stage and more incidence of vascular invasion. The mRNA of HIF-1alpha had significantly positive correlations to that of COX-2, PDGFRA, MMP7, MMP9, MYC, except VEGF. In addition to HIF-1alpha, COX-2 and PDGFRA were also independent prognosticators for OS (P = 0.004 and P = 0.010, respectively and DFS (P = 0.010 and P = 0.038, respectively. Conclusion HIF-1alpha in HCC plays an important role in predicting patient outcome. It may influence HCC biological behaviors and affect the tumor inflammation, angiogenesis and act in concert with the oncogene MYC. Attaching importance to HIF-1alpha in HCC may improve the prognostic and therapeutic technique.

  9. Test chamber for alpha spectrometry

    Science.gov (United States)

    Larsen, Robert P.

    1977-01-01

    Alpha emitters for low-level radiochemical analysis by measurement of alpha spectra are positioned precisely with respect to the location of a surface-barrier detector by means of a chamber having a removable threaded planchet holder. A pedestal on the planchet holder holds a specimen in fixed engagement close to the detector. Insertion of the planchet holder establishes an O-ring seal that permits the chamber to be pumped to a desired vacuum. The detector is protected against accidental contact and resulting damage.

  10. HYDRAULIC CHARACTERIZATIONS OF TORTUOUS FLOW IN PATH DRIP IRRIGATION EMITTER

    Institute of Scientific and Technical Information of China (English)

    LI Yun-kai; YANG Pei-ling; REN Shu-mei; XU Ting-wu

    2006-01-01

    At present, the tortuous emitter has the most advanced performances in drip irrigation. But the theories and methods for designing its flow path have been strictly confidential and the researches on the function of practical guidance have seldom been published. Seven types of most representative tortuous emitting-pipes currently used in agricultural irrigation regions of China were chosen for investigating the geometric parameters of the flow path by means of combining high-precision microscope and AutoCAD technology. By the measurement platform developed by the authors for hydraulic performances of emitters, the free discharge rates from the 7 types of emitters were measured at 9 pressure levels of 1.5 m, 3.0 m, 5.0 m, 7.0 m, 9.0 m, 10.0 m, 11.0 m, 13.0 m and 15.0 m. Then the discharge-pressure relationship, manufacturing variation coefficient, average velocity on the cross-section of flow path and the critical Reynolds number for the flow regime transformation within the paths were analyzed in detail. The results show that both pressure-ascending work pattern and pressure-descending work pattern have some impacts on the discharge rates of tortuous emitters, but the impact level is not significant. The target pressure could be approached by repetitive applications of the two work patterns during pressure regulation. The operation under low pressures has some impacts on the hydraulic performances of emitters, but the impact level is also not significant. The classical model of the discharge-pressure relationship is suitable for the pressure range of 1.5 m -15.0 m. The Reynolds number for fluids within the 7 types of tortuous emitters ranges from =105 to =930. The critical Reynolds number for the flow regime transformation is smaller than that for the routine dimension flow path. The variation coefficient of emitter discharge rates is slightly fluctuating around a certain value within the whole pressure range.

  11. High redshift Lya emitters: clues on the Milky Way infancy

    CERN Document Server

    Salvadori, S; Ferrara, A

    2010-01-01

    With the aim of determining if Milky Way (MW) progenitors could be identified as high redshift Lyman Alpha Emitters (LAEs) we have derived the intrinsic properties of z ~ 5.7 MW progenitors, which are then used to compute their observed Lyman-alpha luminosity, L_alpha, and equivalent width, EW. MW progenitors visible as LAEs are selected according to the canonical observational criterion, L_alpha > 10^42 erg/s and EW > 20 A. Progenitors of MW-like galaxies have L_alpha = 10^(39-43.25) erg/s, making some of them visible as LAEs. In any single MW merger tree realization, typically only 1 (out of ~ 50) progenitor meets the LAE selection criterion, but the probability to have at least one LAE is very high, P = 68%. The identified LAE stars have ages, t_* ~ 150-400 Myr at z ~ 5.7 with the exception of five small progenitors with t_* 10% of the halo very metal-poor stars [Fe/H] < -2, thus establishing a potentially fruitful link between high-z galaxies and the Local Universe.

  12. Source preparations for alpha and beta measurements

    Energy Technology Data Exchange (ETDEWEB)

    Holm, E. [Risoe National Lab., Roskilde (Denmark)

    2001-01-01

    Regarding alpha particle emitters subject for environmental studies, electrodeposition or co-precipitation as fluorides are the most common methods. For electro deposition stainless steel is generally used as cathode material but also other metals such as Ni, Ag, and Cu showed promising results. The use of other anode material than platinum, such as graphite should be investigated. For other purposes such as optimal resolution other more sophisticated methods are used but often resulting in poorer recovery. For beta particle emitters the type of detection system will decide the source preparation. Similar methods as for alpha particle emitters, electrodeposition or precipitation techniques can be used. Due to the continuous energy distribution of the beta pulse height distribution a high resolution is not required. Thicker sources from the precipitates or a stable isotopic carrier can be accepted but correction for absorption in the source must be done. (au)

  13. A systematization of the half-lives for proton emitter nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Martha M.N.; Duarte, Sergio B.; Medeiros, Emil de L.; Tavares, Odilon A.P. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mails: nicke@cbpf.br; sbd@cbpf.br; emil@cbpf.br; oaptavares@cbpf.br

    2007-07-01

    A semiempirical model based on the quantum mechanical tunnelling mechanism of alpha emission from nuclei has been extended to systematize the proton decay half-lives of all existing proton emitter nuclides. These nuclei are far from the beta stability line, near the proton drip line, and only a few experimental data are available. This semiempirical model has been well succeeded for the systematization of alpha decay half-lives, and has predicted for new candidates to alpha emission not yet detected. The purpose of the present extended systematization is to offer a useful tool capable to predict new proton emitter nuclides as well as determine their partial proton emission half-lives with good accuracy. (author)

  14. Hybrid emitter all back contact solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

  15. Emittance investigation of RF photo-injector

    CERN Document Server

    Yang Mao Rong; Li Zheng; Li Ming; Xu Zhou

    2002-01-01

    A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF find in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. The author analyzes the factors which lead the transverse emittance growth and method how to resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show these results are coincident

  16. Minimum emittance in TBA and MBA lattices

    Science.gov (United States)

    Xu, Gang; Peng, Yue-Mei

    2015-03-01

    For reaching a small emittance in a modern light source, triple bend achromats (TBA), theoretical minimum emittance (TME) and even multiple bend achromats (MBA) have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 31/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design.

  17. Faint Lyα Emitters, Star-forming Galaxies, and Damped Lyα Systems

    Science.gov (United States)

    Rauch, M.; Haehnelt, M.; Bunker, A.; Becker, G.; Marleau, F.; Graham, J.; Cristiani, S.; Jarvis, M.; Lacey, C.; Morris, S.; Peroux, C.; Roettgering, H.; Theuns, T.

    2008-10-01

    We have discovered a population of faint single line emitters, likely to be identified with faint z˜ 3 Lyα emitters and with the host galaxies of damped Lyman alpha systems. The objects appear to constitute the bulk of the star-forming galaxies detected so far from the ground, and are likely to provide the gaseous reservoir from which present-day Milky way type galaxies have formed. Unlike color-selected (yman break galaxies, these objects appear to have low star-formation rates, relatively strong Lyalpha emission, and low masses, metallicities, and dust content (s.a. arXiv:0711.1354).

  18. Coefficient Alpha

    OpenAIRE

    Panayiotis Panayides

    2013-01-01

    Heavy reliance on Cronbach’s alpha has been standard practice in many validation studies. However, there seem to be two misconceptions about the interpretation of alpha. First, alpha is mistakenly considered as an indication of unidimensionality and second, that the higher the value of alpha the better. The aim of this study is to clarify these misconceptions with the use of real data from the educational setting. Results showed that high alpha values can be obtained in multidimensional scale...

  19. Bright Single Photon Emitter in Silicon Carbide

    Science.gov (United States)

    Lienhard, Benjamin; Schroeder, Tim; Mouradian, Sara; Dolde, Florian; Trong Tran, Toan; Aharonovich, Igor; Englund, Dirk

    Efficient, on-demand, and robust single photon emitters are of central importance to many areas of quantum information processing. Over the past 10 years, color centers in solids have emerged as excellent single photon emitters. Color centers in diamond are among the most intensively studied single photon emitters, but recently silicon carbide (SiC) has also been demonstrated to be an excellent host material. In contrast to diamond, SiC is a technologically important material that is widely used in optoelectronics, high power electronics, and microelectromechanical systems. It is commercially available in sizes up to 6 inches and processes for device engineering are well developed. We report on a visible-spectrum single photon emitter in 4H-SiC. The emitter is photostable at both room and low temperatures, and it enables 2 million photons/second from unpatterned bulk SiC. We observe two classes of orthogonally polarized emitters, each of which has parallel absorption and emission dipole orientations. Low temperature measurements reveal a narrow zero phonon line with linewidth < 0.1 nm that accounts for more than 30% of the total photoluminescence spectrum. To our knowledge, this SiC color emitter is the brightest stable room-temperature single photon emitter ever observed.

  20. Alpha indirect conversion radioisotope power source

    Energy Technology Data Exchange (ETDEWEB)

    Sychov, Maxim [TRACE Photonics Inc., 1680 West Polk, Charleston, IL 61920 (United States)], E-mail: msychov@yahoo.com; Kavetsky, Alexandr; Yakubova, Galina; Walter, Gabriel; Yousaf, Shahid; Lin, Qian; Chan, Doris; Socarras, Heather; Bower, Kenneth [TRACE Photonics Inc., 1680 West Polk, Charleston, IL 61920 (United States)

    2008-02-15

    Advantages of radioisotope-powered electric generators include long service life, wide temperature range operation and high-energy density. We report development of a long-life generator based on indirect conversion of alpha decay energy. Prototyping used 300 mCi Pu-238 alpha emitter and AlGaAs photovoltaic cells designed for low light intensity conditions. The alpha emitter, phosphor screens, and voltaic arrays were assembled into a power source with the following characteristics: I{sub sc}=14 {mu}A; U{sub oc}=2.3 V; power output -21 {mu}W. Using this prototype we have powered an eight-digit electronic calculator and wrist watch.

  1. Low Emittance X-FEL Development

    CERN Document Server

    Li, K S B; Anghel, A; Bakker, R J; Böge, M; Candel, A E; Dehler, M; Ganter, R; Gough, C; Ingold, G; Leemann, S C; Pedrozzi, M; Raguin, J Y; Rivkin, L; Schlott, V; Streun, A; Wrulich, A F

    2005-01-01

    The Paul Scherrer Institute (PSI) in Switzerland currently develops a Low-Emittance electron-Gun (LEG) based on field-emitter technology [1]. The target is a normalized transverse emittance of 5 10(-8) m rad or less. Such a source is particularly interesting for FELs that target wavelengths below 0.3 nm since it permits a reduction of the required beam-energy and hence, a reduction of the construction- and operational costs of X-ray FELs. That is, for the case that this initial low emittance can be maintained throughout the accelerator. Here we present a concept for a 0.1 nm X-FEL based on LEG, which can be located close to the Swiss Light Source (SLS). Special attention goes to the maintenance of the emittance during the process of acceleration and bunch-compression, in particular in the regimes where either space-charge forces or coherent-synchrotron radiation are of importance.

  2. TPV Systems with Solar Powered Tungsten Emitters

    International Nuclear Information System (INIS)

    A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at λ > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed

  3. Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

    2011-06-16

    Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA), and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3-inch silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel, can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully-integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics.

  4. Performance comparisons of low emittance lattices

    International Nuclear Information System (INIS)

    In this paper, the results of a performance analysis of several low emittance electron storage ring lattices provided by various members of the Lattice Working Group are presented. Altogether, four lattices were investigated. There are two different functions being considered for the low beam emittance rings discussed here. The first is to serve as a Damping Ring (DR), i.e., to provide the emittance damping required for a high energy linear collider. The second is to provide beams for a short wavelength Free Electron Laser (FEL), which is envisioned to operate in the wavelength region near 40 A

  5. Increased expression of alpha- and beta-globin mRNAs at the pituitary following exposure to estrogen during the critical period of neonatal sex differentiation in the rat.

    Science.gov (United States)

    Leffers, H; Navarro, V M; Nielsen, John E; Mayen, A; Pinilla, L; Dalgaard, M; Malagon, M M; Castaño, J P; Skakkebaek, N E; Aguilar, E; Tena-Sempere, M

    2006-04-01

    Deterioration of reproductive health in human and wildlife species during the past decades has drawn considerable attention to the potential adverse effects of exposure to xenosteroids during sensitive periods of sex development. The hypothalamic-pituitary (HP) unit is a key element in the neuroendocrine system controlling development and function of the reproductive axis; the HP unit being highly sensitive to the organizing effects of endogenous and exogenous sex steroids. To gain knowledge on the molecular mode of action and potential biomarkers of exposure to estrogenic compounds at the HP unit, we screened for differentially expressed genes at the pituitary and hypothalamus of rats after neonatal exposure to estradiol benzoate. Our analyses identified persistent up-regulation of alpha- and beta-globin mRNAs at the pituitary following neonatal estrogenization. This finding was confirmed by combination of RT-PCR analyses and in situ hybridization. Induction of alpha- and beta-globin mRNA expression at the pituitary by neonatal exposure to estrogen was demonstrated as dose-dependent and it was persistently detected up to puberty. In contrast, durable up-regulation of alpha- and beta-globin genes was not detected at the hypothalamus, cortex, cerebellum, liver and testis. Finally, enhanced levels of alpha- and beta-globin mRNAs at the pituitary were also demonstrated after neonatal administration of the anti-androgen flutamide. In summary, alpha- and beta-globin genes may prove as sensitive, pituitary-specific biomarkers of exposure to estrogenic (and/or anti-androgenic) compounds at critical periods of sex development, whose potential in the assessment of endocrine disrupting events at the HP unit merits further investigation. PMID:16520034

  6. 3rd Low Emittance Ring Workshop

    CERN Document Server

    2013-01-01

    The workshop brings together different accelerator communities working on the design of ultra low emittance lattices such as synchrotron light sources, damping rings and test facilities for linear colliders and HEP circular colliders. The aim of the workshop is to review the present development s in design of ultra low emittance lattices, the experience and the challenges with the operation of low emittance synchrotrons and the main technological problems. The merging of different accelerator communities is expected to foster ideas exchange and the collaboration both on theoretical, experimental and design issues. Areas for common R programmes will be explored. The workshop will profit from the experience of colleagues who have designed, commissioned and operated lepton ring colliders and synchrotron light sources as well as from the ones involved in future low emittance upgrade programmes of existing rings.

  7. Emittance growth in linear induction accelerators

    CERN Document Server

    Ekdahl, C A; Schulze, M E; Carlson, C A; Frayer, D K; Mostrum, C; Thoma, C H

    2014-01-01

    The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.

  8. Monochromatic gamma emitter for low energy quanta

    CERN Document Server

    Tomova, Z R; Mironova, S A

    2004-01-01

    The possibility of creating of a monochromatic gamma emitter of low energy quanta is analyzed. The idea is based on Daning's scheme. Except for purely scientific problems the monochromator is actual for therapy of wide range of diseases.

  9. Low emittance upgrade for CANDLE project

    CERN Document Server

    Zanyan, G S

    2015-01-01

    To improve the performance of CANDLE synchrotron light source and stay competitive with recently proposed low emittance upgrade programs in the world we have developed new low emittance lattices for CANDLE booster and storage ring. These lattices have been designed taking into account the new developments in magnet fabrication technology and the multi-bend achromat concept. The main design considerations, the linear and non-linear beam dynamics aspects of the modified lattices are presented.

  10. A low-emittance lattice for SPEAR

    Science.gov (United States)

    Safranek, J.; Wiedemann, H.

    1992-08-01

    The design and implementation of a low emittance lattice for the SPEAR storage ring including measurements of the performance of the lattice are presented [J. Safranek, Ph.D. thesis, Stanford University, 1991]. The low emittance lattice is designed to optimize the performance of SPEAR as a synchrotron radiation source while keeping SPEAR hardware changes at a minimum. The horizontal emittance of the electron beam in the low emittance lattice is reduced by a factor of 4 from the previous lattice. This reduces the typical horizontal source size and divergence of the photon beams by a factor of 2 each and increases the photon beam brightness. At 3 GeV the horizontal emittance is 129π nm rad, which makes the low emittance lattice the lowest emittance, running synchrotron radiation source in the world in the 1.5 to 4.0 GeV energy range for the emittance scaled to 3 GeV. The measured vertical emittance was reduced to half that typically seen at SPEAR in the past. The brightness of the photon beams was further increased by reducing βy at the insertion devices to 1.1 m and reducing the energy dispersion at the insertion devices by more than a factor of 2 on average. The horizontal dispersion at the rf cavities was reduced by a factor of nearly 4 which gives much less problems with synchrobetatron resonances. The dynamic and physical apertures of the lattice are large, giving long beam lifetimes and easy injection of electrons. The measurements of the linear optics and intensity dependent phenomena gave reasonable agreement with the design. The overall performance of the machine was very good. Injection rates of 10 to 20 mA/min and larger were achieved routinely, and 100 mA total current was stored. Repeated ramping of stored beam from the injection energy of 2.3 GeV to the running energy of 3.0 GeV was achieved with very little beam loss. This low emittance configuration is expected to be the operating configuration for SPEAR starting in January 1992.

  11. Remote Optical Detection of Alpha Radiation

    International Nuclear Information System (INIS)

    Alpha emitting radiation sources are typically hard to detect with conventional detectors due to the short range of alpha particles in the air. However, previous studies have shown that remote detection of alpha radiation is possible by measuring the ionization-induced fluorescence of air molecules. The alpha-induced ultraviolet (UV) light is mainly emitted by molecular nitrogen and its fluorescence properties are well known. The benefit of this method is the long range of UV photons in the air. Secondly, the detection is possible also under a strong beta and gamma radiation backgrounds as they do not cause localized molecular excitation. In this work, the optical detection was studied using two different detection schemes; spectral separation of fluorescence from the background lighting and coincidence detection of UV photons originating from a single radiative decay event. Our spectrally integrated measurements have shown that one alpha decay event yields up to 400 fluorescence photons in the air and all these UV photons are induced in a 5 ns time-window. On the other hand, the probability of a background coincidence event in 5 ns scale is very rare compared to the number of background photons. This information can be applied in fluorescence coincidence filtering to discriminate the alpha radiation initiated fluorescence signal from much more intense background lighting. A device called HAUVA (Handheld Alpha UV Application) was built during this work for demonstration purposes. HAUVA utilizes spectral filtering and it is designed to detect alpha emitters from a distance of about 40 cm. Using specially selected room lighting, the device is able to separate 1 kBq alpha emitter from the background lighting with 1 second integration time. (author)

  12. Buffett's Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting...

  13. Diamond-based single-photon emitters

    International Nuclear Information System (INIS)

    The exploitation of emerging quantum technologies requires efficient fabrication of key building blocks. Sources of single photons are extremely important across many applications as they can serve as vectors for quantum information-thereby allowing long-range (perhaps even global-scale) quantum states to be made and manipulated for tasks such as quantum communication or distributed quantum computation. At the single-emitter level, quantum sources also afford new possibilities in terms of nanoscopy and bio-marking. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, as they are a photostable solid-state source of single photons at room temperature. In this review, we discuss the state of the art of diamond-based single-photon emitters and highlight their fabrication methodologies. We present the experimental techniques used to characterize the quantum emitters and discuss their photophysical properties. We outline a number of applications including quantum key distribution, bio-marking and sub-diffraction imaging, where diamond-based single emitters are playing a crucial role. We conclude with a discussion of the main challenges and perspectives for employing diamond emitters in quantum information processing.

  14. Variable emittance behavior of smart radiative coating

    Science.gov (United States)

    Guo, Li; Fan, Desong; Li, Qiang

    2016-02-01

    Smart radiative coating on yttria stabilized zirconia (YSZ) substrate was prepared by the sol-gel La{}1-xSr x MnO3 (x = 0.125, 0.175 and 0.2) nanoparticles and the binder composed of terpineol and ethyl cellulose. The crystallized structure, grain size, chemical compositions, magnetization and the surface morphology were characterized. The thermal radiative properties of coating in the infrared range was evaluated from infrared reflectance spectra at various temperatures. A single perovskite structure is detected in sol-gel nanoparticles with size 200 nm. Magnetization measurement reveals that room temperature phase transition samples can be obtained by appropriate Sr substitution. The influence of surface conditions and sintering temperature on the emittance of coating was observed. For rough coatings with root-mean-square roughness 640 nm (x = 0.125) and 800 nm (x = 0.175) , its emittance increment is 0.24 and 0.26 in in the temperature range of 173-373 K. Increasing sintering temperature to 1673 K, coating emittance variation improves to 0.3 and 0.302 respectively. After mechanical polishing treatment, the emittance increment of coatings are enhanced to 0.31 and 0.3, respectively. The results suggested that the emittance variation can be enhanced by reducing surface roughness and increasing sintering temperature of coating.

  15. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    Energy Technology Data Exchange (ETDEWEB)

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  16. Solid-state single-photon emitters

    Science.gov (United States)

    Aharonovich, Igor; Englund, Dirk; Toth, Milos

    2016-10-01

    Single-photon emitters play an important role in many leading quantum technologies. There is still no 'ideal' on-demand single-photon emitter, but a plethora of promising material systems have been developed, and several have transitioned from proof-of-concept to engineering efforts with steadily improving performance. Here, we review recent progress in the race towards true single-photon emitters required for a range of quantum information processing applications. We focus on solid-state systems including quantum dots, defects in solids, two-dimensional hosts and carbon nanotubes, as these are well positioned to benefit from recent breakthroughs in nanofabrication and materials growth techniques. We consider the main challenges and key advantages of each platform, with a focus on scalable on-chip integration and fabrication of identical sources on photonic circuits.

  17. Performance comparisons of low emittance lattices

    International Nuclear Information System (INIS)

    The results of a performance analysis of four low emittance electron storage ring lattices provided to the authors by various members of the Lattice Working Group is presented. Altogether, four lattices were investigated. The beam energies of the four lattices are, respectively, 1.1, 2, 3, 4 GeV). A brief summary of the lattice parameters relevant to this study is given. The performance issues studied include an estimation of the longitudinal emittance expected for each lattice based on the effects of the longitudinal microwave instability, an estimation of the transverse emittance growth of the (required) dense bunches under the influence of intrabeam scattering (IBS), and an estimate of the Touschek lifetime. The analysis described here has been carried out with the LBL accelerator physics code ZAP

  18. Research on Radar Emitter Attribute Recognition Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described in detail. A new attribute recognition method based on attribute measure is presented in this paper. Application example is given, which demonstrates this new method is accurate and effective. Moreover, computer simulation for recognizing the emitter purpose is selected, and compared with classical statistical pattern recognition through simulation. The excellent experimental results demonstrate that this is a brand-new attribute recognition method as compared to existing statistical pattern recognition techniques.

  19. Coupling single emitters to quantum plasmonic circuits

    CERN Document Server

    Huck, Alexander

    2016-01-01

    In recent years the controlled coupling of single photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic non-linearity on a nano-scaled platform. In this article we will review the recent progress on coupling single emitters to nano-wires towards the construction of a new platform for strong light-matter interaction. The control over such a platform might open new doors for quantum information processing and quantum sensing at the nanoscale, and for the study of fundamental physics in the ultra-strong coupling regime.

  20. Quadrupole Transfer Function for Emittance Measurement

    CERN Document Server

    Cameron, Peter; Jansson, Andreas; Tan, Cheng-Yang

    2008-01-01

    Historically the use of the quadrupole moment measurement has been impeded by the requirement for large dynamic range, as well as measurement sensitivity to beam position. We investigate the use of the transfer function technique [1-3] in combination with the sensitivity and 160dB revolution line rejection of the direct diode detection analog front end [4] to open the possibility of an emittance diagnostic that may be implemented without operational complication, quasi- parasitic to the operation of existing tune measurement systems. Such a diagnostic would be particularly useful as an emittance monitor during acceleration ramp development in machines like RHIC and the LHC.

  1. Alpha fetoprotein

    Science.gov (United States)

    Fetal alpha globulin; AFP ... Greater than normal levels of AFP may be due to: Cancer in testes , ovaries, biliary (liver secretion) tract, stomach, or pancreas Cirrhosis of the liver Liver cancer ...

  2. Activation of JAK3, but not JAK1, is critical to interleukin-4 (IL4) stimulated proliferation and requires a membrane-proximal region of IL4 receptor alpha.

    Science.gov (United States)

    Malabarba, M G; Kirken, R A; Rui, H; Koettnitz, K; Kawamura, M; O'Shea, J J; Kalthoff, F S; Farrar, W L

    1995-04-21

    The tyrosine kinases JAK1 and JAK3 have been shown to undergo tyrosine phosphorylation in response to interleukin-2 (IL), IL4, IL7, and IL9, cytokines which share the common IL2 receptor gamma-chain (IL2R gamma), and evidence has been found for a preferential coupling of JAK3 to IL2R gamma and JAK1 to IL2R beta. Here we show, using human premyeloid TF-1 cells, that IL4 stimulates JAK3 to a larger extent than JAK1, based upon three different evaluation criteria. These include a more vigorous tyrosine phosphorylation of JAK3 as measured by anti-phosphotyrosine immunoblotting, a more marked activation of JAK3 as determined by in vitro tyrosine kinase assays and a more manifest presence of JAK3 in activated IL4-receptor complexes. These observations suggest that IL4 receptor signal transduction does not depend on equimolar heterodimerization of JAK1 and JAK3 following IL4-induced heterodimerization of IL4R alpha and IL2R gamma. Indeed, when human IL4R alpha was stably expressed in mouse BA/F3 cells, robust IL4-induced proliferation and JAK3 activation occurred without detectable involvement of JAK1, JAK2, or TYK2. The present study suggests that JAK1 plays a subordinate role in IL4 receptor signaling, and that in certain cells exclusive JAK3 activation may mediate IL4-induced cell growth. Moreover, mutational analysis of human IL4R alpha showed that a membrane-proximal cytoplasmic region was critical for JAK3 activation, while the I4R motif was not, which is compatible with a role of JAK3 upstream of the recruitment of the insulin receptor substrate-1/4PS signaling proteins by IL4 receptors.

  3. Targeted alpha-radionuclide therapy of functionally critically located gliomas with {sup 213}Bi-DOTA-[Thi{sup 8},Met(O{sub 2}){sup 11}]-substance P: a pilot trial

    Energy Technology Data Exchange (ETDEWEB)

    Cordier, D.; Merlo, A. [University Hospitals, Division of Neurosurgery, Basel (Switzerland); Forrer, F.; Good, S.; Mueller-Brand, J. [University Hospitals, Institute of Nuclear Medicine, Basel (Switzerland); Bruchertseifer, F.; Morgenstern, A.; Apostolidis, C. [Institute for Transuranium Elements, European Commission, Joint Research Centre, Karlsruhe (Germany); Maecke, H. [University Hospitals, Institute of Nuclear Medicine, Basel (Switzerland); University Hospital Basel, Nuclear Medicine and Radiological Chemistry, Basel (Switzerland); Reubi, J.C. [University of Berne, Institute of Pathology, Berne (Switzerland)

    2010-07-15

    Functionally critically located gliomas represent a challenging subgroup of intrinsic brain neoplasms. Standard therapeutic recommendations often cannot be applied, because radical treatment and preservation of neurological function are contrary goals. The successful targeting of gliomas with locally injected beta radiation-emitting {sup 90}Y-DOTAGA-substance P has been shown previously. However, in critically located tumours, the mean tissue range of 5 mm of {sup 90}Y may seriously damage adjacent brain areas. In contrast, the alpha radiation-emitting radionuclide {sup 213}Bi with a mean tissue range of 81 {mu}m may have a more favourable toxicity profile. Therefore, we evaluated locally injected {sup 213}Bi-DOTA-substance P in patients with critically located gliomas as the primary therapeutic modality. In a pilot study, we included five patients with critically located gliomas (WHO grades II-IV). After diagnosis by biopsy, {sup 213}Bi-DOTA-substance P was locally injected, followed by serial SPECT/CT and MR imaging and blood sampling. Besides feasibility and toxicity, the functional outcome was evaluated. Targeted radiopeptide therapy using {sup 213}Bi-DOTA-substance P was feasible and tolerated without additional neurological deficit. No local or systemic toxicity was observed. {sup 213}Bi-DOTA-substance P showed high retention at the target site. MR imaging was suggestive of radiation-induced necrosis and demarcation of the tumours, which was validated by subsequent resection. This study provides proof of concept that targeted local radiotherapy using {sup 213}Bi-DOTA-substance P is feasible and may represent an innovative and effective treatment for critically located gliomas. Primarily non-operable gliomas may become resectable with this treatment, thereby possibly improving the prognosis. (orig.)

  4. The island of alpha activity close to the double magic nucleus 100Sn

    International Nuclear Information System (INIS)

    Up to now, 14 alpha emitters have been identified among the neutrondeficient isotopes of Te, I, Xe and Cs. None of the nine formulae of 1975 mass predictions can reproduce the Q-values of all these alpha emitters. Nevertheless, one can say that some good estimates are obtained by using the masses given by: Myers; Groote-Hilf-Takahashi, Liran Zeldes; Jaenecke-Eynon and Jaenecke. If the Q-value is known, our semiempirical formula, based on the fission theory of alpha decay, allow to obtain the best estimates of the partial life-times. This relationship is used to predict new alpha emitters with atomic numbers Z = 52-61. (authors)

  5. International workshop on emittance preservation in linear colliders

    International Nuclear Information System (INIS)

    The extremely low emittances, which are the essential feature for any linear collider, are far beyond those of the present high-energy accelerators. Every part of the linear-collider accelerator complex is liable to blow up them to a fatal degree. Above all, the main linac is the most critical part, since it will have an unprecedented length, through which very highly populated bunches should be accelerated without a faint increase of emittances. A lot of efforts have been paid, mainly theoretically, to settle this problem at all institutes. Any convincing conclusions are not yet reached. Furthermore, there are six approaches of substantially different schemes (Tesla, DLC, JLC, NLC, VLEPP, CLIC), each requiring its own way to tackle the problem. In this workshop, many up-to-date R and D results were presented by each institute. Judging from what were discussed, we may well say that the R and D work has advanced to such a level that the different approaches are rather helping each other to reach more concrete results. (J.P.N.)

  6. Emittance growth from electron beam modulation

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  7. Longitudinal emittance measurements at REX-ISOLDE

    CERN Document Server

    Fraser, M A; Jones, R.M.; Jones, R M; Pasini, M; Posocco, P A; Voulot, D; Wenander, F

    2012-01-01

    We report on measurements of the longitudinal emittance at the Radioactive ion beam EXperiment (REX) at ISOLDE, CERN. The rms longitudinal emittance was measured as 0.34 ± 0.08 π ns keV/u at the output of the RFQ and as 0.36 ± 0.04π ns keV/u in front of the third 7-gap split-ring resonator (7G3) using the three-gradient technique; systematic errors are not included but are estimated at approximately 10%. The 86% emittance was measured a factor of approximately 4.4 times larger than the rms emittance at 1.48 ± 0.2 and 1.55 ± 0.12π ns keV/u at the RFQ and 7G3, respectively. The REX switchyard magnet was used as a spectrometer to analyse the energy spread of the beam as it was manipulated by varying the voltage of the rebuncher (ReB) and 7G3 cavities operating at non-accelerating phases. The transfer matrix for a multi-gap bunching cavity is derived and suitably truncated to allow for the accurate reconstruction of the beam parameters from measurement. The technique for measuring the energy spread was rig...

  8. THz imaging system with the IJJ emitter

    Science.gov (United States)

    Tsujimoto, Manabu; Minami, Hidetoshi; Sawamura, Masashi; Delfanazari, Kaveh; Yamamoto, Takashi; Kashiwagi, Takanari; Kadowaki, Kazuo

    2011-03-01

    The intrinsic Josephson junction (IJJ) emitter consisted of thousands of IJJs uniformly stacked in single crystalline high-Tc superconductor Bi 2 Sr 2 CaCu 2 O8 + δ (Bi-2212) [L. Ozyuzer et al., Science 318, (2007) 1291.] is expected to be a novel source of the continuous terahertz electromagnetic waves (THz-waves). The maximum emission power of tens of microwatts recently obtained with the mesa structure of IJJs seems to be sufficient to make use of the IJJ emitter for some practical applications such as THz imaging. According to the cavity resonance condition, we can control the radiation frequency by changing the geometrical size of the mesa. In this study, we develop the THz imaging system with IJJ emitter. In the presentation, we will show some transparent images of standard specimens obtained by the raster scanning method. Also, we will mention some problems to be solved for the future applications of the IJJ emitter. CREST-JST, WPI-MANA, Strategic Initiative A (University of Tsukuba).

  9. Innovative Field Emitters for High-Voltage Electronic Devices

    Science.gov (United States)

    Sominski, G. G.; Sezonov, V. E.; Taradaev, E. P.; Tumareva, T. A.; Zadiranov, Yu. M.; Kornishin, S. Yu.; Stepanova, A. N.

    2015-12-01

    We describe multitip field emitters with protective coatings, which were developed in Peter the Great St. Petersburg Polytechnic University. The coatings ensure long-term operation of the emitters under high currents and technical vacuum. Innovative multi-layer emitters composed of contacting nanolayers of materials with different work functions are presented as well. The possibility by using the developed emitters in high-voltage electronic devices is demonstrated.

  10. RF Emitter geolocation using PDOA algorithms and UAVs - A strategy from emitter detection to location prediction

    OpenAIRE

    Engebråten, Sondre Andreas

    2015-01-01

    In this thesis, I explored strategies for locating an RF emitter. Expanding on an idea conceived at Norwegian Defence Research Establishment (FFI), of using small, cheap RSS sensors and Unmanned Aerial Vehicles (UAVs) to search for unknown RF emitters. Cheap and simple, will in most cases, mean that some property of the system suffers, compared to more complicated and expensive systems. This thesis attempts to circumvent these issues by using multiple sensors instead of one ...

  11. What is so super about super-emitters? Characterizing methane high emitters from natural gas infrastructure

    Science.gov (United States)

    Zavala Araiza, D.; Lyon, D. R.; Alvarez, R.; Harriss, R. C.; Palacios, V.; Hamburg, S.

    2015-12-01

    Methane emissions across the natural gas supply chain are dominated at any one time by a few high-emitters (super-emitters or fat-tail of the distribution), often underrepresented in published datasets used to construct emission inventories. Characterization of high-emitters is essential for improving emission estimates based on atmospheric data (top-down) and emission inventories (bottom-up). The population of high-emitters (e.g. 10-20% of sites that account for 80-90% of the emissions) is temporally and spatially dynamic. As a consequence, it is challenging to design sampling methods and construct estimates that accurately represent their frequency and magnitude of emissions. We present new methods to derive facility-specific emission distribution functions that explicitly integrate the influence of the relatively rare super-emitters. These methods were applied in the Barnett Shale region to construct a custom emission inventory that is then compared to top-down emission estimates for the region. We offer a methodological framework relevant to the design of future sampling campaigns, in which these high-emitters are seamlessly incorporated to representative emissions distributions. This framework can be applied to heterogeneous oil and gas production regions across geographies to obtain accurate regional emission estimates. Additionally, we characterize emissions relative to the fraction of a facility's total methane throughput; an effective metric to identify sites with excess emissions resulting from avoidable operating conditions, such as malfunctioning equipment (defined here as functional super-emitters). This work suggests that identifying functional super-emitters and correcting their avoidable operating conditions would result in significant emission reductions. However, due to their spatiotemporal dynamic behavior, achieving and maintaining uniformly low emissions across the entire population of sites will require mitigation steps (e.g. leak detection

  12. The alpha immunotherapy - A successful solution in cancer treatment

    International Nuclear Information System (INIS)

    Full text: Radiation has been used in cancer therapy for many years. While, in the past the treatment involved mainly use of relatively low energy beta-emitters, more recently it was shown that isotopes emitting alpha particles have been more effective and selective against blood-borne cancers, widespread tumors and residual cells remaining after surgical intervention. This study shows that radioimmunotherapy (RIT) with α emitters may be therapeutically more effective than RIT with conventional β emitters. In the process of designing and developing the radioimmunotherapy procedures, the selection of the isotope is a major factor. This selection depends on a number of criteria and parameters, affecting usefulness and feasibility. Usefulness is directly related to the radiological performance of the ionising radiation in relation to tissue and its morphology, with a major distinction between the effects of alpha and beta-particles. Usefulness is also related to the pharmacodynamic performance of the isotope-carrier (e.g. antibody) complex, where the proper choice of isotope radiodecay half-life is essential. Feasibility depends on availability of the components in the isotope-ligand-carrier complex, and also on convenience and safety aspects in the preparation and the handling of the materials as well as in their application in patients. Alpha immunotherapy is based on emission of alpha particles by radionuclides. Due to its short physical t1/2, 213Bi appears to be especially suitable for use in conjunction with fast-clearing fragments; its 440-keV α emission also can be used for quantitation by external scintigraphy. Bismuth-213, a short-lived alpha particle emitting radionuclide, is generated from the decay of 225Ac, which has a half-life of 10 days. The development of a clinical 225Ac/213Bi generator and the preparation of a 213Bi radiolabeled antibody for radioimmunotherapy of leukemia is reported. Alpha emitting radionuclides are amongst the most promising

  13. Double Emittance Exchanger as a Bunch Compressor for the MaRIE XFEL electron beam line at 1GeV

    Energy Technology Data Exchange (ETDEWEB)

    Malyzhenkov, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Northern Illinois Univ., DeKalb, IL (United States); Yampolsky, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carlsten, Bruce Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-22

    We demonstrate an alternative realization of a bunch compressor (specifically the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space.We compare our results with a traditional bunch compressor realized via chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beam line and analyze the eigen-emittances evolution to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR-effects in our scheme resulting in critical emittance growth and introduce alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  14. Quantum emitters dynamically coupled to a quantum field

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J. [Departamento de Física, Universidad de los Andes, A.A. 4976, Bogotá (Colombia); Johnson, N. F. [Department of Physics, University of Miami, Coral Gables, Miami, FL 33124 (United States)

    2013-12-04

    We study theoretically the dynamical response of a set of solid-state quantum emitters arbitrarily coupled to a single-mode microcavity system. Ramping the matter-field coupling strength in round trips, we quantify the hysteresis or irreversible quantum dynamics. The matter-field system is modeled as a finite-size Dicke model which has previously been used to describe equilibrium (including quantum phase transition) properties of systems such as quantum dots in a microcavity. Here we extend this model to address non-equilibrium situations. Analyzing the system’s quantum fidelity, we find that the near-adiabatic regime exhibits the richest phenomena, with a strong asymmetry in the internal collective dynamics depending on which phase is chosen as the starting point. We also explore signatures of the crossing of the critical points on the radiation subsystem by monitoring its Wigner function; then, the subsystem can exhibit the emergence of non-classicality and complexity.

  15. Quantum emitters dynamically coupled to a quantum field

    Science.gov (United States)

    Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J.; Johnson, N. F.

    2013-12-01

    We study theoretically the dynamical response of a set of solid-state quantum emitters arbitrarily coupled to a single-mode microcavity system. Ramping the matter-field coupling strength in round trips, we quantify the hysteresis or irreversible quantum dynamics. The matter-field system is modeled as a finite-size Dicke model which has previously been used to describe equilibrium (including quantum phase transition) properties of systems such as quantum dots in a microcavity. Here we extend this model to address non-equilibrium situations. Analyzing the system's quantum fidelity, we find that the near-adiabatic regime exhibits the richest phenomena, with a strong asymmetry in the internal collective dynamics depending on which phase is chosen as the starting point. We also explore signatures of the crossing of the critical points on the radiation subsystem by monitoring its Wigner function; then, the subsystem can exhibit the emergence of non-classicality and complexity.

  16. Small horizontal emittance in the TESLA damping ring

    International Nuclear Information System (INIS)

    The present TESLA damping ring is designed for a normalized horizontal emittance of 8x10-6 m. γ-γ collisions at the TESLA linear collider will benefit from a further decrease of the horizontal emittance. This paper reviews the processes which limit the horizontal emittance in the damping ring. Preliminary estimates on the smallest horizontal emittance for the present TESLA damping ring design as well as an ultimate limit of the emittance reachable with the TESLA damping ring concept will be given

  17. Studying fringe field effect of a field emitter array

    International Nuclear Information System (INIS)

    Field emitter arrays on heavy As-doped Si wafer are studied in vacuum nanoelectronics diode configuration. Different shapes of emitters are considered: cone-shaped point-emitters and cylinder-shaped sharp-edge-emitters are compared. Micro scale field enhancement factor on the edge of cylindrical emitter was calculated via home-developed Matlab application and the results are presented. Two types of anode geometry are proposed: plane anode and spherical anode. Experimental and modelling results of surface electric field distribution are presented. The spherical shape of anode allows higher voltage (and higher field emission current) without destructive arcs risk

  18. $\\alpha_s$ review (2016)

    CERN Document Server

    d'Enterria, David

    2016-01-01

    The current world-average of the strong coupling at the Z pole mass, $\\alpha_s(m^2_{Z}) = 0.1181 \\pm 0.0013$, is obtained from a comparison of perturbative QCD calculations computed, at least, at next-to-next-to-leading-order accuracy, to a set of 6 groups of experimental observables: (i) lattice QCD "data", (ii) $\\tau$ hadronic decays, (iii) proton structure functions, (iv) event shapes and jet rates in $e^+e^-$ collisions, (v) Z boson hadronic decays, and (vi) top-quark cross sections in p-p collisions. In addition, at least 8 other $\\alpha_s$ extractions, usually with a lower level of theoretical and/or experimental precision today, have been proposed: pion, $\\Upsilon$, W hadronic decays; soft and hard fragmentation functions; jets cross sections in pp, e-p and $\\gamma$-p collisions; and photon F$_2$ structure function in $\\gamma\\,\\gamma$ collisions. These 14 $\\alpha_s$ determinations are reviewed, and the perspectives of reduction of their present uncertainties are discussed.

  19. Quantification of actinide alpha-radiation damage in minerals and ceramics.

    Science.gov (United States)

    Farnan, Ian; Cho, Herman; Weber, William J

    2007-01-11

    There are large amounts of heavy alpha-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is consensus that actinides that have been separated from spent nuclear fuel should be immobilized within mineral-based ceramics rather than glass because of their superior aqueous durability and lower risk of accidental criticality. However, in the long term, the alpha-decay taking place in these ceramics will severely disrupt their crystalline structure and reduce their durability. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per alpha-decay. At present, this number is estimated to be 1,000-2,000 atoms/alpha in zircon. Here we report nuclear magnetic resonance, spin-counting experiments that measure close to 5,000 atoms/alpha in radiation-damaged natural zircons. New radiological nuclear magnetic resonance measurements on highly radioactive, 239Pu zircon show damage similar to that caused by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of half-life or loading levels (dose rate). On the basis of these measurements, the initially crystalline structure of a 10 weight per cent 239Pu zircon would be amorphous after only 1,400 years in a geological repository (desired immobilization timescales are of the order of 250,000 years). These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics in terms of an atomistic understanding of the fundamental damage event. PMID:17215840

  20. An ultracold low emittance electron source

    CERN Document Server

    Xia, G; Murray, A J; Bellan, L; Bertsche, W; Appleby, R B; Mete, O; Chattopadhyay, S

    2014-01-01

    Ultracold atom-based electron sources have recently been proposed as an alternative to the conventional photo-injectors or thermionic electron guns widely used in modern particle accelerators. The advantages of ultracold atom-based electron sources lie in the fact that the electrons extracted from the plasma (created from near threshold photo-ionization of ultracold atoms) have a very low temperature, i.e. down to tens of Kelvin. Extraction of these electrons has the potential for producing very low emittance electron bunches. These features are crucial for the next generation of particle accelerators, including free electron lasers, plasma-based accelerators and future linear colliders. The source also has many potential direct applications, including ultrafast electron diffraction (UED) and electron microscopy, due to its intrinsically high coherence. In this paper, the basic mechanism of ultracold electron beam production is discussed and our new research facility for an ultracold, low emittance electron s...

  1. Discovery of a Giant Lya Emitter Near the Reionization Epoch

    Energy Technology Data Exchange (ETDEWEB)

    Ouchi, Masami; Ono, Yoshiaki; Egami, Eiichi; Saito, Tomoki; Oguri, Masamune; McCarthy, Patrick J.; Farrah, Duncan; Kashikawa, Nobunari; Momcheva, Ivelina; Shimasaku, Kazuhiro; Nakanishi, Kouichiro; Furusawa, Hisanori; Akiyama, Masayuki; Dunlop, James S.; Mortier, Angela M.J.; Okamura, Sadanori; Hayashi, Masao; Cirasuolo, Michele; Dressler, Alan; Iye, Masanori; Jarvis, Matt.J.

    2008-08-01

    We report the discovery of a giant Ly{alpha} emitter (LAE) with a Spitzer/IRAC counterpart near the reionization epoch at z = 6.595. The giant LAE is found from the extensive 1 deg{sup 2} Subaru narrow-band survey for z = 6.6 LAEs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy of Keck/DEIMOS and Magellan/IMACS. Among our 207 LAE candidates, this LAE is not only the brightest narrow-band object with L(Ly{alpha}) = 3.9 {+-} 0.2 x 10{sup 43} erg s{sup -1} in our survey volume of 10{sup 6} Mpc{sup 3}, but also a spatially extended Ly{alpha} nebula with the largest isophotal area whose major axis is at least {approx_equal} 3-inches. This object is more likely to be a large Ly{alpha} nebula with a size of {approx}> 17-kpc than to be a strongly-lensed galaxy by a foreground object. Our Keck spectrum with medium-high spectral and spatial resolutions suggests that the velocity width is v{sub FWHM} = 251 {+-} 21 km s{sup -1}, and that the line-center velocity changes by {approx_equal} 60 km s{sup -1} in a 10-kpc range. The stellar mass and star-formation rate are estimated to be 0.9-5.0 x 10{sup 10}M{sub {circle_dot}} and > 34 M{sub {circle_dot}}yr{sup -1}, respectively, from the combination of deep optical to infrared images of Subaru, UKIDSS-Ultra Deep Survey, and Spitzer/IRAC. Although the nature of this object is not yet clearly understood, this could be an important object for studying cooling clouds accreting onto a massive halo, or forming-massive galaxies with significant outflows contributing to cosmic reionization and metal enrichment of inter-galactic medium.

  2. Large-area lanthanum hexaboride electron emitter

    Science.gov (United States)

    Goebel, D. M.; Hirooka, Y.; Sketchley, T. A.

    1985-09-01

    The characteristics of lanthanum-boron thermionic electron emitters are discussed, and a large-area, continuously operating cathode assembly and heater are described. Impurity production and structural problems involving the support of the LaB6 have been eliminated in the presented configuration. The performance of the cathode in a plasma discharge, where surface modification occurs by ion sputtering, is presented. Problem areas which affect lifetime and emission current capability are discussed.

  3. Emittance growths in resonance crossing at FFAGs

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab; Pang, X.; Wang, F.; Wang, X.; Lee, S.Y.; /Indiana U.

    2007-10-01

    Scaling laws of the emittance growth for a beam crossing the 6th-order systematic space-charge resonances and the random-octupole driven 4th-order resonance are obtained by numerical multi-particle simulations. These laws can be important in setting the minimum acceleration rate and maximum tolerable resonance strength for the design of non-scaling fixed-field alternating gradient accelerators.

  4. Studies on anodic oxide coating with low absorptance and high emittance on aluminum alloy 2024

    Energy Technology Data Exchange (ETDEWEB)

    Siva Kumar, C. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India); Sharma, A.K. [Thermal Process Section, ISRO Satellite Centre, Vimanapura Post, Bangalore (India); Mahendra, K.N.; Mayanna, S.M. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India)

    2000-01-01

    Anodization of AA 2024 in sulfuric acid bath containing glycerol, lactic acid and ammonium metavenadate has been studied to develop white anodic oxide coating. Investigation on the influence of various operating parameters - coating thickness, current density and ammonium metavenadate concentration on the optical properties was carried out to optimize the process. Infrared, atomic absorption spectroscopic techniques and scanning electron micrograph were used to characterize the coating. The obtained oxide coating provides a ratio of solar absorptance ({alpha}) to infrared emittance ({epsilon}), as low as 0.2. The optical properties and hardness values measured under optimum experimental conditions support its use as a thermal control coating.

  5. Direct Alpha Analysis for Forensic Samples (DAAFS)

    International Nuclear Information System (INIS)

    The goal of the DAAFS project is to deliver a field deployable direct alpha sample spectrometry system. This system is designed to rectify current gaps in pure alpha emitting material detection. The system comprises, firstly, an evaluation of multiple innovative methods for rapid on-site sample collection of difficult to detect alpha RN contamination. Secondly, the incorporation of an experimental alpha spectrometry analysis software suite, 'ADAM', is provided for performing the required on-site deconvolution of the complex alpha spectra arising from the direct sample measurement. Software simulation of collected alpha spectra will be handled by 'AASI', which will simulate alpha spectra as a training and analysis verification tool. Thirdly, a Concept of Operations (ConOps) for the system implementation in RN field teams is included. This combination of the swipe methodology, advanced swipe treatment equipment, mobile field laboratories, and the state of the art analysis software suite will provide RN response teams with the capability to identify and rapidly (i.e., hours as opposed to days) quantify low activity and difficult to detect alpha emitters. Further expert analysis support is available to field teams by sharing of raw spectral data via email with off-site laboratories. The proposed system provides the solution to this identified capability gap, specifically, a field-deployable real-time alpha detection system. The system comprises: a non-destructive particle sampler, standardized swipe sampling methods, a self-contained field alpha spectrometry system and an integrated data management/communications tool allowing for real-time raw-data tracking and data sharing. This system also provides responders with the type/quantity of RN material for improved safeguards, forensics, and contamination mitigation applications. (author)

  6. On the Diffuse Lyman-alpha Halo Around Lyman-alpha Emitting Galaxies

    CERN Document Server

    Lake, Ethan; Cen, Renyue; Sadoun, Raphael; Momose, Rieko; Ouchi, Masami

    2015-01-01

    Ly$\\alpha$ photons scattered by neutral hydrogen atoms in the circumgalactic media or produced in the halos of star-forming galaxies are expected to lead to extended Ly$\\alpha$ emission around galaxies. Such low surface brightness Ly$\\alpha$ halos (LAHs) have been detected by stacking Ly$\\alpha$ images of high-redshift star-forming galaxies. We study the origin of LAHs by performing radiative transfer modeling of nine $z=3.1$ Lyman-Alpha Emitters (LAEs) in a high resolution hydrodynamic galaxy formation simulation. We develop a method of computing the mean Ly$\\alpha$ surface brightness profile of each LAE by effectively integrating over many different observing directions. Without adjusting any parameters, our model yields an average Ly$\\alpha$ surface brightness profile in remarkable agreement with observations. We find that observed LAHs can not be accounted for solely by photons originating from the central LAE and scattered to large radii by hydrogen atoms in the circumgalactic gas. Instead, Ly$\\alpha$ em...

  7. Emissivity Tuned Emitter for RTPV Power Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carl M. Stoots; Robert C. O' Brien; Troy M. Howe

    2012-03-01

    Every mission launched by NASA to the outer planets has produced unexpected results. The Voyager I and II, Galileo, and Cassini missions produced images and collected scientific data that totally revolutionized our understanding of the solar system and the formation of the planetary systems. These missions were enabled by the use of nuclear power. Because of the distances from the Sun, electrical power was produced using the radioactive decay of a plutonium isotope. Radioisotopic Thermoelectric Generators (RTGs) used in the past and currently used Multi-Mission RTGs (MMRTGs) provide power for space missions. Unfortunately, RTGs rely on thermocouples to convert heat to electricity and are inherently inefficient ({approx} 3-7% thermal to electric efficiency). A Radioisotope Thermal Photovoltaic (RTPV) power source has the potential to reduce the specific mass of the onboard power supply by increasing the efficiency of thermal to electric conversion. In an RTPV, a radioisotope heats an emitter, which emits light to a photovoltaic (PV) cell, which converts the light into electricity. Developing an emitter tuned to the desired wavelength of the photovoltaic is a key part in increasing overall performance. Researchers at the NASA Glenn Research Center (GRC) have built a Thermal Photovoltaic (TPV) system, that utilizes a simulated General Purpose Heat Source (GPHS) from a MMRTG to heat a tantalum emitter. The GPHS is a block of graphite roughly 10 cm by 10 cm by 5 cm. A fully loaded GPHS produces 250 w of thermal power and weighs 1.6 kgs. The GRC system relies on the GPHS unit radiating at 1200 K to a tantalum emitter that, in turn, radiates light to a GaInAs photo-voltaic cell. The GRC claims system efficiency of conversion of 15%. The specific mass is around 167 kg/kWe. A RTPV power source that utilized a ceramic or ceramic-metal (cermet) matrix would allow for the combination of the heat source, canister, and emitter into one compact unit, and allow variation in size

  8. The $\\alpha-\\alpha$ fishbone potential revisited

    CERN Document Server

    Day, J P; Elhanafy, M; Smith, E; Woodhouse, R; Papp, Z

    2011-01-01

    The fishbone potential of composite particles simulates the Pauli effect by nonlocal terms. We determine the $\\alpha-\\alpha$ fishbone potential by simultaneously fitting to two-$\\alpha$ resonance energies, experimental phase shifts and three-$\\alpha$ binding energies. We found that essentially a simple gaussian can provide a good description of two-$\\alpha$ and three-$\\alpha$ experimental data without invoking three-body potentials.

  9. Wavelength locking of single emitters and multi-emitter modules: simulation and experiments

    Science.gov (United States)

    Yanson, Dan; Rappaport, Noam; Peleg, Ophir; Berk, Yuri; Dahan, Nir; Klumel, Genady; Baskin, Ilya; Levy, Moshe

    2016-03-01

    Wavelength-stabilized high-brightness single emitters are commonly used in fiber-coupled laser diode modules for pumping Yb-doped lasers at 976 nm, and Nd-doped ones at 808 nm. We investigate the spectral behavior of single emitters under wavelength-selective feedback from a volume Bragg (or hologram) grating (VBG) in a multi-emitter module. By integrating a full VBG model as a multi-layer thin film structure with commercial raytracing software, we simulated wavelength locking conditions as a function of beam divergence and angular alignment tolerances. Good correlation between the simulated VBG feedback strength and experimentally measured locking ranges, in both VBG misalignment angle and laser temperature, is demonstrated. The challenges of assembling multi-emitter modules based on beam-stacked optical architectures are specifically addressed, where the wavelength locking conditions must be achieved simultaneously with high fiber coupling efficiency for each emitter in the module. It is shown that angular misorientation between fast and slow-axis collimating optics can have a dramatic effect on the spectral and power performance of the module. We report the development of our NEON-S wavelength-stabilized fiber laser pump module, which uses a VBG to provide wavelength-selective optical feedback in the collimated portion of the beam. Powered by our purpose-developed high-brightness single emitters, the module delivers 47 W output at 11 A from an 0.15 NA fiber and a 0.3 nm linewidth at 976 nm. Preliminary wavelength-locking results at 808 nm are also presented.

  10. Alpha One Foundation

    Science.gov (United States)

    ... Tested Find Support Find Doctor What Is Alpha-1? Alpha-1 Antitrypsin Deficiency (Alpha-1) is a ... results for inhaled augmentation More News Our Number One Goal: Find a cure for Alpha-1. Website ...

  11. High brightness fiber laser pump sources based on single emitters and multiple single emitters

    Science.gov (United States)

    Scheller, Torsten; Wagner, Lars; Wolf, Jürgen; Bonati, Guido; Dörfel, Falk; Gabler, Thomas

    2008-02-01

    Driven by the potential of the fiber laser market, the development of high brightness pump sources has been pushed during the last years. The main approaches to reach the targets of this market had been the direct coupling of single emitters (SE) on the one hand and the beam shaping of bars and stacks on the other hand, which often causes higher cost per watt. Meanwhile the power of single emitters with 100μm emitter size for direct coupling increased dramatically, which also pushed a new generation of wide stripe emitters or multi emitters (ME) of up to 1000μm emitter size respectively "minibars" with apertures of 3 to 5mm. The advantage of this emitter type compared to traditional bars is it's scalability to power levels of 40W to 60W combined with a small aperture which gives advantages when coupling into a fiber. We show concepts using this multiple single emitters for fiber coupled systems of 25W up to 40W out of a 100μm fiber NA 0.22 with a reasonable optical efficiency. Taking into account a further efficiency optimization and an increase in power of these devices in the near future, the EUR/W ratio pushed by the fiber laser manufacturer will further decrease. Results will be shown as well for higher power pump sources. Additional state of the art tapered fiber bundles for photonic crystal fibers are used to combine 7 (19) pump sources to output powers of 100W (370W) out of a 130μm (250μm) fiber NA 0.6 with nominal 20W per port. Improving those TFB's in the near future and utilizing 40W per pump leg, an output power of even 750W out of 250μm fiber NA 0.6 will be possible. Combined Counter- and Co-Propagated pumping of the fiber will then lead to the first 1kW fiber laser oscillator.

  12. Delay modeling of bipolar ECL/EFL (Emitter-Coupled Logic/Emitter-Follower-Logic) circuits

    Science.gov (United States)

    Yang, Andrew T.

    1986-08-01

    This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance of the circuits with a minimum expenditure of computation time. This goal is achieved by the use of proper circuit transient models on which analytical delay expressions can be derived with accurate results. The delay-model developed in this report is general enough to handle complex digital circuits with multiple inputs or/and multiple levels. The important effects of input slew rate are also included in the model.

  13. Enhancing selectivity of infrared emitters through quality-factor matching

    Science.gov (United States)

    Sakr, Enas; Zhou, Zhiguang; Bermel, Peter

    2015-09-01

    It has recently been proposed that designing selective emitters with photonic crystals (PhCs) or plasmonic metamaterials can suppress low-energy photon emission, while enhancing higher-energy photon emission. Here, we will consider multiple approaches to designing and fabricating nanophotonic structures concentrating infrared thermal radiation at energies above a critical threshold. These are based on quality factor matching, in which one creates resonant cavities that couple light out at the same rate that the underlying materials emit it. When this quality-factor matching is done properly, emissivities can approach those of a blackbody, but only within a selected range of thermal photon energies. One potential application is for improving the conversion of heat to electricity via a thermophotovoltaic (TPV) system, by using thermal radiation to illuminate a photovoltaic (PV) diode. In this study, realistic simulations of system efficiencies are performed using finite-difference time domain (FDTD) and rigorous coupled wave analysis (RCWA) to capture both thermal radiation and PV diode absorption. We first consider a previously studied 2D molybdenum photonic crystal with a commercially-available silicon PV diode, which can yield TPV efficiencies up to 26.2%. Second, a 1D-periodic samarium-doped glass emitter with a gallium antimonide (GaSb) PV diode is presented, which can yield efficiencies up to 38.5%. Finally, a 2D tungsten photonic crystal with a 1D integrated, chirped filter and the GaSb PV diode can yield efficiencies up to 38.2%; however, the fabrication procedure is expected to be more challenging. The advantages and disadvantages of each strategy will be discussed.

  14. A critical review of radiation effects on borosilicate glasses

    International Nuclear Information System (INIS)

    Most of the experimental values have been obtained by loading the glass with alpha emitters like Cm 244 and Pu 238. The data existing in literature on stored energy, and density variation are presented and discussed. Attention is given to the variation of the leaching rate due to the radiation effect. Samples loaded with alpha emitters have given data up to 0.17 dpa and such bombarded with heavy ions show large effects due to dose rate effects. A study on defect formation has shown that under electrons irradiation, formation of bubbles is possible. (DG)

  15. Ballasted and electrically steerable carbon nanotube field emitters

    Science.gov (United States)

    Cole, M. T.; Li, C.; Qu, K.; Zhang, Y.; Wang, B.; Pribat, D.; Milne, W. I.

    2012-09-01

    Here we present our on-going efforts toward the development of stable ballasted carbon nanotube-based field emitters employing hydrothermally synthesized zinc oxide nanowires and thin film silicon-on-insulator substrates. The semiconducting channel in each controllably limits the emission current thereby preventing detrimental burn-out of individual emitters that occurs due to unavoidable statistical variability in emitter characteristics, particularly in their length. Fabrication details and emitter characterization are discussed in addition to their field emission performance. The development of a beam steerable triode electron emitter formed from hexagonal carbon nanotube arrays with central focusing nanotube electrodes, is also described. Numerical ab-initio simulations are presented to account for the empirical emission characteristics. Our engineered ballasted emitters have shown some of the lowest reported lifetime variations (sources.

  16. Correlated spontaneous emission of fluorescent emitters mediated by single plasmons

    CERN Document Server

    Bouchet, Dorian; Ithurria, Sandrine; Gulinatti, Angelo; Rech, Ivan; Carminati, Rémi; De Wilde, Yannick; Krachmalnicoff, Valentina

    2016-01-01

    Manipulating the spontaneous emission of a fluorescent emitter can be achieved by placing the emitter in a nanostructured environment. A privileged spot is occupied by plasmonic structures that provide a strong confinement of the electromagnetic field, which results in an enhancement of the emitter-environment interaction. While plasmonic nanostructures have been widely exploited to control the emission properties of single photon emitters, performing the coupling between quantum emitters with plasmons poses a huge challenge. In this Letter we report on a first crucial step towards this goal by the observation of correlated emission between a single CdSe/CdS/ZnS quantum dot exhibiting single photon statistics and a fluorescent nanobead located micrometers apart. This is accomplished by coupling both emitters to a silver nanowire. Single-plasmons are created on the latter from the quantum dot, and transfer energy to excite in turn the fluorescent nanobead.

  17. Infrared spectral normal emittance/emissivity comparison

    Science.gov (United States)

    Hanssen, L.; Wilthan, B.; Filtz, J.-R.; Hameury, J.; Girard, F.; Battuello, M.; Ishii, J.; Hollandt, J.; Monte, C.

    2016-01-01

    The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes' infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide. The comparison has been performed over a spectral range of 2 μm to 14 μm, and a temperature range from 23 °C to 800 °C. Artefacts included in the comparison are potential standards: oxidized Inconel, boron nitride, and silicon carbide. The measurement instrumentation and techniques used for emittance scales are unique for each NMI, including the temperature ranges covered as well as the artefact sizes required. For example, all three common types of spectral instruments are represented: dispersive grating monochromator, Fourier transform and filter-based spectrometers. More than 2000 data points (combinations of material, wavelength and temperature) were compared. Ninety-eight percent (98%) of the data points were in agreement, with differences to weighted mean values less than the expanded uncertainties calculated from the individual NMI uncertainties and uncertainties related to the comparison process. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Thermal emittance measurements of a cesium potassium antimonide photocathode

    OpenAIRE

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-01-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56+/-0.03 mm-mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  19. Thermal emittance measurements of a cesium potassium antimonide photocathode

    Science.gov (United States)

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-05-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56±0.03 mm mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  20. Multiple emitter location and signal parameter estimation

    Science.gov (United States)

    Schmidt, R. O.

    1986-03-01

    Multiple signal classification (MUSIC) techniques involved in determining the parameters of multiple wavefronts arriving at an antenna array are discussed. A MUSIC algorithm is described, which provides asymptotically unbiased estimates of (1) the number of signals, (2) directions of arrival (or emitter locations), (3) strengths and cross correlations among the incident waveforms, and (4) the strength of noise/interference. The example of the use of the algorithm as a multiple frequency estimator operating on time series is examined. Comparisons of this method with methods based on maximum likelihood and maximum entropy, as well as conventional beamforming, are presented.

  1. Low emittance electron beam optics commissioning in Indus-2

    International Nuclear Information System (INIS)

    Currently Indus-2 is normally operated with beam emittance of 85 nmrad at 2.0 GeV. In order to reduce the beam emittance to half of this value its dispersion function has been modified by properly choosing the quadrupoles strengths of the lattice. At this low beam emittance optics dynamic aperture reduces and may not be sufficient for beam injection thus a procedure has been evolved and implemented to shift the beam emittance of stored beam at 2.0 GeV. (author)

  2. Intelligent Variable Emittance Panels Using New, ""True"" Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This work further developed a highly promising Variable Emittance technology for spacecraft thermal control based on Conducting Polymer (CP) electrochromics...

  3. $\\alpha_{s}$ from the (revised) ALEPH data for $\\tau$ decay

    CERN Document Server

    Boito, Diogo; Maltman, Kim; Osborne, James; Peris, Santiago

    2014-01-01

    We present a new analysis of $\\alpha_s$ from hadronic $\\tau$ decays based on the recently revised ALEPH data. The analysis is based on a strategy which we previously applied to the OPAL data. We critically compare our strategy to the one traditionally used and comment on the main differences. Our analysis yields the values $\\alpha_s(m_\\tau^2)=0.296\\pm 0.010$ using fixed-order perturbation theory, and $\\alpha_s(m_\\tau^2)=0.310\\pm 0.014$ using contour-improved perturbation theory. Averaging these values with our previously obtained values from the OPAL data, we find $\\alpha_s(m_\\tau^2)=0.303\\pm 0.009$, respectively, $\\alpha_s(m_\\tau^2)=0.319\\pm 0.012$, as the most reliable results for $\\alpha_s$ from $\\tau$ decays currently available.

  4. Barium depletion in hollow cathode emitters

    Energy Technology Data Exchange (ETDEWEB)

    Polk, James E., E-mail: james.e.polk@jpl.nasa.gov; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Capece, Angela M. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  5. Muon Emittance Exchange with a Potato Slicer

    Energy Technology Data Exchange (ETDEWEB)

    Summers, D. J. [Univ. of Mississippi, Oxford, MS (United States); Hart, T. L. [Univ. of Mississippi, Oxford, MS (United States); Acosta, J. G. [Univ. of Mississippi, Oxford, MS (United States); Cremaldi, L. M. [Univ. of Mississippi, Oxford, MS (United States); Oliveros, S. J. [Univ. of Mississippi, Oxford, MS (United States); Perera, L. P. [Univ. of Mississippi, Oxford, MS (United States); Neuffer, D. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-04-15

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.

  6. Narrowband infrared emitters for combat ID

    Science.gov (United States)

    Pralle, Martin U.; Puscasu, Irina; Daly, James; Fallon, Keith; Loges, Peter; Greenwald, Anton; Johnson, Edward

    2007-04-01

    There is a strong desire to create narrowband infrared light sources as personnel beacons for application in infrared Identify Friend or Foe (IFF) systems. This demand has augmented dramatically in recent years with the reports of friendly fire casualties in Afghanistan and Iraq. ICx Photonics' photonic crystal enhanced TM (PCE TM) infrared emitter technology affords the possibility of creating narrowband IR light sources tuned to specific IR wavebands (near 1-2 microns, mid 3-5 microns, and long 8-12 microns) making it the ideal solution for infrared IFF. This technology is based on a metal coated 2D photonic crystal of air holes in a silicon substrate. Upon thermal excitation the photonic crystal modifies the emitted yielding narrowband IR light with center wavelength commensurate with the periodicity of the lattice. We have integrated this technology with microhotplate MEMS devices to yield 15mW IR light sources in the 3-5 micron waveband with wall plug efficiencies in excess of 10%, 2 orders of magnitude more efficient that conventional IR LEDs. We have further extended this technology into the LWIR with a light source that produces 9 mW of 8-12 micron light at an efficiency of 8%. Viewing distances >500 meters were observed with fielded camera technologies, ideal for ground to ground troop identification. When grouped into an emitter panel, the viewing distances were extended to 5 miles, ideal for ground to air identification.

  7. Muon Emittance Exchange with a Potato Slicer

    CERN Document Server

    Summers, D J; Acosta, J G; Cremaldi, L M; Oliveros, S J; Perera, L P; Neuffer, D V

    2015-01-01

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long ...

  8. Minimizing Emittance for the CLIC Damping Ring

    CERN Document Server

    Braun, H; Levitchev, E; Piminov, P; Schulte, Daniel; Siniatkin, S; Vobly, P P; Zimmermann, Frank; Zolotarev, Konstantin V; CERN. Geneva

    2006-01-01

    The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6·109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology the other on permanent magnets are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. For optimized wigglers, only bunches for a single machine pulse may need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 36...

  9. Barium depletion in hollow cathode emitters

    International Nuclear Information System (INIS)

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values

  10. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  11. Minimization of the emittance growth of multi-charge particle beams in the charge stripping section of RAON

    International Nuclear Information System (INIS)

    The charge stripping section of the Rare isotope Accelerator Of Newness (RAON), which is one of the critical components to achieve a high power of 400 kW with a short lianc, is a source of transverse emittance growth. The dominant effects are the angular straggling in the charge stripper required to increase the charge state of the beam and chromatic aberrations in the dispersive section required to separate the selected ion beam from the various ion beams produced in the stripper. Since the main source of transverse emittance growth in the stripper is the angular straggling, it can be compensated for by changing the angle of the phase ellipse. Therefore the emittance growth is minimized by optimizing the Twiss parameters at the stripper. The emittance growth in the charge selection section is also minimized by the correction of high-order aberrations using six sextupole magnets. In this paper, we present a method to minimize the transverse emittance growth in the stripper by changing the Twiss parameters and in the charge selection section by using sextupole magnets

  12. Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromat

    CERN Document Server

    Huang, Xiyang; Cui, Xiaohao; Xu, Gang

    2014-01-01

    Coherent synchrotron radiation (CSR) effect at a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and of high peak current. Suppression of the emittance growth induced by CSR is essential and critical to preserve the beam quality and to help improve the machine performance. To evaluate the CSR effect analytically, we have proposed a novel method, which enabled us to obtain generic conditions of cancelling the CSR linear effect in a two-dipole achromat. In this paper, it illustrates that with this method the CSR-cancellation condition can be obtained for a TBA with symmetric layout, which is independent of concrete element parameters, and to a large extent, the initial beam distribution. Implementation of found condition in concrete optics design of a TBA is discussed, and the proposed condition is verified through numerical simulations.

  13. Noninterceptive transverse emittance measurements using BPM for Chinese ADS R&D project

    Science.gov (United States)

    Wang, Zhi-Jun; Feng, Chi; He, Yuan; Dou, Weiping; Tao, Yue; Chen, Wei-long; Jia, Huan; Liu, Shu-hui; Wang, Wang-sheng; Zhang, Yong; Wu, Jian-qiang; Zhang, Sheng-hu; Zhang, X. L.

    2016-04-01

    The noninterceptive four-dimensional transverse emittance measurements are essential for commissioning the high power continue-wave (CW) proton linacs as well as their operations. The conventional emittance measuring devices such as slits and wire scanners are not well suited under these conditions due to sure beam damages. Therefore, the method of using noninterceptive Beam Position Monitor (BPM) is developed and demonstrated on Injector Scheme II at the Chinese Accelerator Driven Sub-critical System (China-ADS) proofing facility inside Institute of Modern Physics (IMP) [1]. The results of measurements are in good agreements with wire scanners and slits at low duty-factor pulsed (LDFP) beam. In this paper, the detailed experiment designs, data analysis and result benchmarking are presented.

  14. An H-alpha search for over-dense regions at z=2.23

    CERN Document Server

    Matsuda, Y; Geach, J E; Best, P N; Sobral, D; Tanaka, I; Ohta, K; Kurk, J; Iwata, I; Bielby, Rich; Wardlow, J L; Bower, R G; Fanidakis, N; Ivison, R J; Kodama, T; Yamada, T; Mawatari, K; Casali, M

    2011-01-01

    We present the results of a narrow-band (H2S1, 2.121/0.021um) imaging search with WFCAM/UKIRT for H-alpha emitters around several potential signposts of rare (10^-7-10^-8 Mpc^-3) over-dense regions at z=2.23: an over-density of QSOs (2QZ cluster), a powerful, high-redshift radio galaxy (HzRG), and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrow-band emitter candidates down to emission-line fluxes of 0.5-1 x 10^-16 erg s^-1 cm^-2, across a total area of 0.56 sq. degrees (2.1 x 10^5 comoving Mpc at z=2.23) in these fields. The BzK colours of the emitters suggest that at least 80% of our sample are likely to be H-alpha emitters (HAEs) at z=2.23. This is one of the largest HAE samples known at z>2. We find modest (~3-sigma) local over-densities of emitters associated with all the three targets. In the 2QZ cluster field, the emitters show a striking filamentary structure connecting four of the z=2.23 QSOs extending over 30Mpc (comoving). I...

  15. Jamming of Quantum Emitters by Active Coated Nanoparticles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2013-01-01

    effectively cloak the emitters to a far-field observer is reported and explained through thorough near- and far-field investigations. This property offers an interesting route toward the jamming of quantum emitters/nanoantennas that might be of potential use, for instance, in biological fluorescence assays...

  16. Emitter space charge layer transit time in bipolar junction transistors

    Science.gov (United States)

    Rustagi, S. C.; Chattopadhyaya, S. K.

    1981-04-01

    The charge defined emitter space charge layer transit times of double diffused transistors have been calculated using a regional approach, and compared with the corresponding base transit times. The results obtained for emitter space-charge layer transit times have been discussed with reference to the capacitance analysis of Morgan and Smit (1960) for graded p-n junctions.

  17. Spectral beam combining of multi-single emitters

    Science.gov (United States)

    Wang, Baohua; Guo, Weirong; Guo, Zhijie; Xu, Dan; Zhu, Jing; Zhang, Qiang; Yang, Thomas; Chen, Xiaohua

    2016-03-01

    Spectral beam combination expands the output power while keeps the beam quality of the combined beam almost the same as that of a single emitter. Spectral beam combination has been successfully achieved for high power fiber lasers, diode laser arrays and diode laser stacks. We have recently achieved the spectral beam combination of multiple single emitter diode lasers. Spatial beam combination and beam transformation are employed before beams from 25 single emitter diode lasers can be spectrally combined. An average output power about 220W, a spectral bandwidth less than 9 nm (95% energy), a beam quality similar to that of a single emitter and electro-optical conversion efficiency over 46% are achieved. In this paper, Rigorous Coupled Wave analysis is used to numerically evaluate the influence of emitter width, emitter pitch and focal length of transform lens on diffraction efficiency of the grating and spectral bandwidth. To assess the chance of catastrophic optical mirror damage (COMD), the optical power in the internal cavity of a free running emitter and the optical power in the grating external cavity of a wavelength locked emitter are theoretically analyzed. Advantages and disadvantages of spectral beam combination are concluded.

  18. Emittance measurements of low-energy beam line at KVI

    NARCIS (Netherlands)

    Toprek, D; Formanoy, [No Value

    2006-01-01

    In this paper is represented the results of beam profile measurements of He-3(+) beam delivered from ECR ion source at KVI. The beam emittance is estimated by varying quadrupole method. The estimated values for the beam emittance at the different profile grid locations along the transport beam line

  19. Coated nano-particle jamming of quantum emitters

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2012-01-01

    Spherical active coated nano-particles are examined analytically and numerically in the presence of one, two or four quantum emitters (electric Hertzian dipoles). The ability of the coated nano-particle to effectively cloak the emitters to a far-field observer is reported. This offers an...

  20. Properties of nanolasers based on few discrete emitters

    DEFF Research Database (Denmark)

    Lund, Anders Mølbjerg; Nielsen, Per Kær; Lorke, Michael;

    2012-01-01

    emitters and 100 photon states the density matrix has more than 2.5 × 106 elements. We have been able to simplify the problem significantly by adiabatically eliminating the photon-assisted polarizations and the correlations between emitters and cavity [3]. This results in a set of rate equations...

  1. Bunch transverse emittance increase in electron storage rings

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper a theoretical framework to estimate the bunch transverse emittance growing in electron storage rings due to short range transverse wakefield of the machine is established. New equilibrium emittance equations are derived and applied to explain the experimentally obtained results in ATF damping ring. This equation will be useful for linear collider damping ring design.

  2. Emittance compensation of CW DC-gun photoinjector

    International Nuclear Information System (INIS)

    Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)

  3. Emittance Measurements for Beams Extracted from LECR3 Ion Source

    Institute of Scientific and Technical Information of China (English)

    CaoYun; ZhaoHongwei; MaLei; ZhangZimin

    2003-01-01

    High quality ion beams are required by IMP cyclotron and atomic physics research, so it is important to research and measure beam emitt ance of ECR ion source. Intense beams extracted from ECR ion source usually have low energy, so it is suitable to use Electric-Sweep Scanner to measure the emittance. This kind of measurement is popularly used at ECR ion source, and it has some prominent merits such as high accuracy, very short time of data processing and easy expressing of the emittance pattern. So we designed and built this emittance scanner to measure emittance of the ion beams produced by LECR3 ion source. The structure of the ESS is shown in Fig.l, and the photo of the ESS is shown in Fig.2.

  4. Superradiance of a subwavelength array of independent classical nonlinear emitters

    CERN Document Server

    Nefedkin, N E; Zyablovsky, A A; Pukhov, A A; Vinogradov, A P; Lisyansky, A A

    2015-01-01

    We suggest a mechanism for the emergence of a superradiance burst in a subwavelength array of nonlinear classical emitters. We assume that the emitters interact via their common field of radiative response and that they may have an arbitrary distribution of initially phases. We show that only if this distribution is not uniform, a non-zero field of radiative response arises leading to a superradiance burst. Although this field cannot synchronize the emitters, it forces fast oscillations of a classical nonlinear emitter to have long-period envelopes. Constructive interference in the envelopes creates a large dipole moment of the array which results in a superradiance pulse. The intensity of the superradiance is proportional to the squared number of the emitters, which envelopes participate in the fluctuation.

  5. Evaluations of carbon nanotube field emitters for electron microscopy

    International Nuclear Information System (INIS)

    Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I-V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6x109 A/m2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

  6. Self-consistent, unbiased root-mean-square emittance analysis

    Science.gov (United States)

    Stockli, Martin P.; Welton, R. F.; Keller, R.

    2004-05-01

    We present a self-consistent method for analyzing measured emittance data that yields unbiased estimates for the root-mean-square (rms) emittance. The self-consistent, unbiased elliptical exclusion analysis uses an ellipse to determine the bias from the data outside the ellipse, before calculating the rms emittance from the bias-subtracted data within the ellipse. Increasing the ellipse size until the rms emittance estimate saturates allows for determining the minimum elliptical area that includes all real signals, even those buried in the noise. Variations of the ellipse shape and orientations are used to test the robustness of the results. Background fluctuations cause fluctuations in the rms emittance estimate, which are an estimate of the uncertainty incurred through the analysis.

  7. Emittance compensation for an SRF photo injector

    Energy Technology Data Exchange (ETDEWEB)

    Vennekate, H.; Lu, P. [HZDR (Germany); TU Dresden (Germany); Arnold, A.; Mucek, P.; Teichert, J.; Xiang, R. [HZDR (Germany); Kamps, T. [HZB (Germany); Kneisel, P. [JLab (Germany); Voelker, J. [HZB (Germany); Humboldt Universitaet Berlin (Germany); Volkov, V. [BINP (Germany); Will, I. [MBI (Germany)

    2013-07-01

    The development of a superconducting photo injector is an ongoing challenge at the HZDR in Dresden. Several milestones like the first operation of a half cell niobium cavity in 2002 and the worldwide first beam transfer from a 3 1/2-cell SRF gun into an actual accelerator structure have already been accomplished. Nevertheless, as superconducting electron sources are of great interest for future ERL or cw operated FEL projects, studies to improve their output parameters and stability continue to get them on the same level as their normal conducting counterparts. The talk discusses several of the current approaches to reduce the transversal emittance of the next 3 1/2-cell cavity at the HZDR including the installation of a superconducting solenoid within the gun's cryostat.

  8. Gamma emitters in Hong Kong water

    International Nuclear Information System (INIS)

    Radioactivity in water originates from natural and artificial sources. The development of a nuclear powerplant near Hong Kong necessitates that attention be given to formulating techniques to assess the possible resultant environmental radioactive contamination. Water samples collected from various sites in Hong Kong in the spring and summer of 1987, representing seawater, river water, reservoir water, drinking water, and underground water were studied through gamma-ray spectral analysis. Only gamma emitters in the U238 and Th232 series and K40 were detected. No fission product was detected with specific activity above 0.1 Bq/kg. The data could be the baseline for future monitoring of the radioactivity released from a nuclear plant being built at a 50-km distance from Hong Kong. The variation of detected specific activities may be due to geological differences and the effect of plants. 1 ref., 3 tabs

  9. Space Charge Effects in Rectilinear Motion Emittance

    CERN Document Server

    Chen, C

    2000-01-01

    This report summarizes the presentations and discussions over a wide range of topics in Working Group I at the Second ICFA Advanced Accelerator Workshop on Physics of High-Brightness Beams held at University of California at Los $9 Angeles (UCLA), November 9-12, 1999. Latest developments towards to a better understanding of high-brightness photoinjectors were reported. The design and commissioning of the Los Alamos National Laboratory (LANL) Low-Energy $9 Demonstration Accelerator (LEDA) Radio-Frequency Quadrupole (RFQ) were reported. The problem of beam halo formation was discussed in both beam transport systems and the SLAC 50 MW 11.4 GHz periodic permanent magnet (PPM) focusing $9 klystron amplifier. A new class of corkscrewing elliptic beam equilibria was reported, and applications of such novel beam equilibria in controlling of charge-density and velocity fluctuations, beam halo formation and emittance $9 growth were discussed. Pattern formation in proton rings was also discussed.

  10. Gross alpha radioactivity of drinking water in Venezuela

    International Nuclear Information System (INIS)

    Bottled mineral water is consumed by a large population in Venezuela. The alpha emitters concentration was measured in samples of bottled water and water springs collected near the surface. Approximately 30% of the total mineral water suppliers was monitored. a database on natural and artificial radioactivity in drinking water was produced. Results indicate that 54% of the waters sampled contain a total alpha radioactivity of less than 0.185 Bql-1 and only 12% above 0.37 Bql-1. Our results revealed a total annual dose of 2.3 mSv year-1. (author)

  11. The Ly$\\alpha$ emission from high-$z$ galaxies hosting strong Damped Ly$\\alpha$ systems

    CERN Document Server

    Joshi, Ravi; Noterdaeme, Pasquier; Petitjean, Patrick

    2016-01-01

    We study the average Ly$\\alpha$ emission associated with high-$z$ strong (log $N$(H I) $\\ge$ 21) damped Ly$\\alpha$ systems (DLAs). We report Ly$\\alpha$ luminosities ($L_{\\rm Ly\\alpha}$) for the full as well as various sub-samples based on $N$(H I), $z$, $(r-i)$ colours of QSOs and rest equivalent width of Si II$\\lambda$1526 line (i.e., $W_{1526}$). For the full sample, we find $L_{\\rm Ly\\alpha}$$< 10^{41} (3\\sigma)\\ \\rm erg\\ s^{-1}$ with a $2.8\\sigma$ level detection of Ly$\\alpha$ emission in the red part of the DLA trough. The $L_{\\rm Ly\\alpha}$ is found to be higher for systems with higher $W_{1526}$ with its peak, detected at $\\geq 3\\sigma$, redshifted by about 300-400 $\\rm km\\ s^{-1}$ with respect to the systemic absorption redshift, as seen in Lyman Break Galaxies (LBGs) and Ly$\\alpha$ emitters. A clear signature of a double-hump Ly$\\alpha$ profile is seen when we consider $W_{1526} \\ge 0.4$ \\AA\\ and $(r-i) < 0.05$. Based on the known correlation between metallicity and $W_{1526}$, we interpret our...

  12. Physical electrostatics of small field emitter arrays/clusters

    Science.gov (United States)

    Forbes, Richard G.

    2016-08-01

    This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field emitter arrays/clusters. Using the "floating sphere at emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like emitters. For the isolated emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated emitters) image charges. For the 2-emitter system, formulas are found for charge-transfer ("charge-blunting") effects and neighbor-field effects, for widely spaced and for "sufficiently closely spaced" emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-emitter equispaced linear array, differential charge-blunting and differential neighbor-field effects occur, but differential charge-blunting effects are dominant, and cause the "exposed" outer emitters to have higher AFEF (γ0) than the central emitter (γ1). Formulas are found for the exposure ratio Ξ = γ0/γ1, for large and for sufficiently small separations. The FSEPP model for an isolated emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM implementations is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which is different from the FSEPP-model formulas. This discrepancy needs to be investigated, using systematic Laplace-based simulations and appropriate results

  13. Effect of thin emitter set-back layer on GaAs delta-doped emitter bipolar junction transistor

    Science.gov (United States)

    Lew, K. L.; Yoon, S. F.

    2005-05-01

    GaAs delta-doped emitter bipolar junction transistors (δ-BJT) with different emitter set-back layer thicknesses of 10to50nm were fabricated to study the emitter set-back layer thickness effect on device dc performance. We found that the current gain decreases following decrease in the emitter set-back layer thickness. A detailed analysis was performed to explain this phenomenon, which is believed to be caused by reduction of the effective barrier height in the δ-BJT. This is due to change in the electric-field distribution in the delta-doped structure caused by the built-in potential of the base-emitter (B-E ) junction. Considering the recombination and barrier height reduction effects, the thickness of the emitter set-back layer should be designed according to the B-E junction depletion width with a tolerance of ±5nm. The dc performance of a δ-BJT designed based on this criteria is compared to that of a Al0.25Ga0.75As /GaAs heterojunction bipolar transistor (HBT). Both devices employed base doping of 2×1019cm-3 and base-to-emitter doping ratio of 40. Large emitter area (AE≈1.6×10-5cm-2) and small emitter area (AE≈1.35×10-6cm-2) device current gains of 40 and 20, respectively, were obtained in both types of transistors passivated by (NH4)2S treatment. The measured current gain of the GaAs δ-BJT is the highest reported for a homojunction device with such high base-to-emitter doping ratio normally used in HBT devices.

  14. A survey of the alpha-nucleon interaction

    International Nuclear Information System (INIS)

    A survey of the alpha-nucleon interaction is made. The experimental work on angular distributions of differential scattering cross-sections and polarizations in proton-alpha and neutron-alpha scattering is described. The phenomenological approach which includes the study of both local and non-local potentials reproducing the experimental alpha-nucleon scattering data, is discussed. Basic studies of the alpha-nucleon interaction attempting to build an interaction between an alpha particle and a nucleon from first principles are then described. A critical discussion of the results with some concluding remarks suggesting the direction for further investigation is made. (author)

  15. Liquid scintillation counting techniques for the determination of some alpha emitting actinides: a review

    International Nuclear Information System (INIS)

    The present report is a review of the work on liquid scintillation counting techniques, for the determination of alpha emitting actinides like uranium, plutonium, americium etc; for the last three decades (1970-1999). It covers the progress that has taken place in conventional liquid scintillation counting employing various solvents, scintillators and extractants. There is gradual development in instrumentation from integral counting of alpha emitters to alpha liquid scintillation spectrometry to resolve and identify different alpha emitters. These advancements have led to Pulse Shape Analysis (PSA) and Photon Electron Rejecting Alpha Liquid Scintillation Spectrometry (PERALS) techniques for the determination of the alpha emitters in the presence of beta and gamma activity. These techniques allow the determination of actinides at very low levels which has increased their applications to almost all the fields of chemistry; be it biomedical, environmental, geological or process chemistry of nuclear fuels. The development of biphasic technique using various extractants to separate different elements and counting in presence of one another has been made possible. Inorganic scintillators have been recently developed which have the advantage of eliminating effects of quenching and presence of beta/gamma emitting actinides. This review will serve as a reference to those who want to carry out work in the field of determination of actinides using liquid scintillation counting techniques. (author)

  16. Gross alpha determination in radioactive wastes from nuclear power plants using the track registration technique

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Navarro, M.J. [Universidad Politecnica de Madrid (UPM) E.T.S.I de Caminos, Canales y Puertos, Profesor Aranguren, s/n, 28040 Madrid (Spain)]. E-mail: he04@caminos.upm.es; Pujol, Ll. [Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), Alfonso XII, 3, 28014 Madrid (Spain); Gonzalez-Gonzalez, J.A. [Universidad Politecnica de Madrid (UPM) E.T.S.I de Caminos, Canales y Puertos, Profesor Aranguren, s/n, 28040 Madrid (Spain)

    2007-03-15

    Low and intermediate level nuclear wastes (ion-exchange resins and evaporator concentrates) essentially contain beta and gamma emitters, with very few alpha emitters. Several techniques may be used to determine gross alpha activity but, in this case, solid-state nuclear track detectors (SSNTDs) are a suitable technique for gross alpha determination because track detectors are not sensitive to beta and gamma emitters. Also, this technique is simple and inexpensive. In this paper, we studied the parameters (background, efficiency and self-absorption) that could affect the gross alpha determination using SSNTDs for both sample preparation methods, the 'dry method' with tensioactives and the 'wet method'. For the 'dry method', a self-absorption curve for {sup 241}Am standard was prepared using a set of varying thickness of sodium salt and for two different tensioactives: Tween{sup (R)}20 and Teg. The results showed that, below 1mg/cm{sup 2}, the self-absorption factor can be considered similar for both tensioactives and equal to unity. Several detectors for gross alpha determination were compared and we found that the most suitable techniques were ZnS(Ag) solid scintillator and track detectors. Both detectors were used to compare radioactive waste samples. Finally, the proposed methods ('dry method' with Teg tensioactive and 'wet method') using track detectors were tested by analysing the gross alpha activity of several radioactive wastes.

  17. Courant-Snyder invariant density screening method for emittance analysis

    Institute of Scientific and Technical Information of China (English)

    SUN Ji-Lei; TANG Jing-Yu; JING Han-Tao

    2011-01-01

    Emittance is an important characteristic of describing charged particle beams.In hadron accelerators,we often meet irregular beam distributions that are not appropriately described by a single rms emittance or 95% emittance or total emittance.In this paper,it is pointed out that in many cases a beam halo should be described with very different Courant-Snyder parameters from the ones used for the beam core.A new method - the Courant-Snyder invariant density screening method - is introduced for analyzing emittance data clearly and accurately.The method treats the emittance data from both measurements and numerical simulations.The method uses the statistical distribution of the beam around each particle in phase space to mark its local density parameter,and then uses the density distribution to calculate the beam parameters such as the Courant-Snyder parameters and emittance for different beam boundary definitions.The method has been used in the calculations for.beams from different sources,and shows its advantages over other methods.An application code based on the method including the graphic interface has also been designed.

  18. Low-emittance tuning at the Cornell Electron Storage Ring

    CERN Document Server

    Shanks, James; Sagan, David

    2013-01-01

    In 2008 the Cornell Electron/Positron Storage Ring (CESR) was reconfigured from an electron/positron collider to serve as a testbed for the International Linear Collider (ILC) damping rings. One of the primary goals of the CESR Test Accelerator (CesrTA) project is to develop low emittance tuning techniques to achieve sub-10pm geometric vertical emittance at 2.085 GeV. This paper discusses the tuning methods used at CesrTA to achieve low-emittance conditions. A minimum vertical emittance of 8.7 +2.9/-3.4(sys) +/-0.2(stat) pm has been achieved at 2.085 GeV. In various configurations and beam energies the correction technique routinely achieves vertical emittance <15 pm after correction. Beam-based measurement and correction requires about 15 minutes. Simulations modeling the effects of magnet misalignments, BPM errors, and emittance correction algorithm suggest the residual vertical emittance measured at the conclusion of the tuning procedure is dominated by sources other than optics errors and misalignments...

  19. Interband Tunneling for Hole Injection in III-Nitride Ultraviolet Emitters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuewei [The Ohio State Univ., Columbus, OH (United States); Krishnamoorthy, Sriram [The Ohio State Univ., Columbus, OH (United States); Johnson, Jared M. [The Ohio State Univ., Columbus, OH (United States); Akyol, Fatih [The Ohio State Univ., Columbus, OH (United States); Allerman, Andrew A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moseley, Michael William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Armstrong, Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hwang, Jinwoo [The Ohio State Univ., Columbus, OH (United States); Rajan, Siddharth [The Ohio State Univ., Columbus, OH (United States)

    2015-04-09

    Low p-type conductivity and high contact resistance remain a critical problem in wide band gap AlGaN-based ultraviolet light emitters due to the high acceptor ionization energy. In this work, interband tunneling is demonstrated for non-equilibrium injection of holes through the use of ultra-thin polarization-engineered layers that enhance tunneling probability by several orders of magnitude over a PN homojunction. Al0.3Ga0.7N interband tunnel junctions with a lowresistance of 5.6 × 10-4 Ω cm2 were obtained and integrated on ultraviolet light emitting diodes.Tunnel injection of holes was used to realize GaN-free ultraviolet light emitters with bottom and top n-type Al0.3Ga0.7N contacts. At an emission wavelength of 327 nm, stable output power of 6 W/cm2 at a current density of 120 A/cm2 with a forward voltage of 5.9 V was achieved. Our demonstration of efficient interband tunneling could enable device designs for higher efficiency ultraviolet emitters.

  20. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    Science.gov (United States)

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-01-01

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays. PMID:27090440

  1. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    Science.gov (United States)

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-04-19

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  2. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    Science.gov (United States)

    Golovin, G.; Banerjee, S.; Liu, C.; Chen, S.; Zhang, J.; Zhao, B.; Zhang, P.; Veale, M.; Wilson, M.; Seller, P.; Umstadter, D.

    2016-04-01

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  3. Scaled, circular-emitter Penning SPS for intense H- beams

    International Nuclear Information System (INIS)

    The Los Alamos versions of the Penning Surface-Plasma Source (SPS) routinely generate H- ion beams with pulsed currents over 100 mA. However, these sources employ geometries that result in the extraction of slit beams (0.5 x 10 mm2). Our modeling with the SNOW code indicates that the beam from a 5.4-mm-diam circular emitter will have lower emittance and divergence for transport to and injection into our radio-frequency quadrupole (RFQ) accelerator. This paper describes a newly constructed Penning SPS that has most of its discharge chamber dimensions scaled up by a factor of 4 to accommodate this circular emitter

  4. Method and apparatus for multispray emitter for mass spectrometry

    Science.gov (United States)

    Smith, Richard D.; Tang, Keqi; Lin, Yuehe

    2004-12-14

    A method and apparatus that utilizes two or more emitters simultaneously to form an electrospray of a sample that is then directed into a mass spectrometer, thereby increasing the total ion current introduced into an electrospray ionization mass spectrometer, given a liquid flow rate of a sample. The method and apparatus are most conveniently constructed as an array of spray emitters fabricated on a single chip, however, the present invention encompasses any apparatus wherein two or more emitters are simultaneously utilized to form an electrospray of a sample that is then directed into a mass spectrometer.

  5. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  6. Molecular breast imaging with gamma emitters.

    Science.gov (United States)

    Schillaci, O; Spanu, A; Danieli, R; Madeddu, G

    2013-12-01

    Following a diagnosis of breast cancer (BC), the early detection of local recurrence is important to define appropriate therapeutic strategies and increase the chances of a cure. In fact, despite major progress in surgical treatment, radiotherapy, and chemotherapy protocols, tumor recurrence is still a major problem. Moreover, the diagnosis of recurrence with conventional imaging methods can be difficult as a result of the presence of scar tissue. Molecular breast imaging (MBI) with gamma-ray emitting radiotracers may be very useful in this clinical setting, because it is not affected by the post-therapy morphologic changes. This review summarises the applications of 99mTc-sestamibi and 99mTc-tetrofosmin, the two most employed gamma emitter radiopharmaceuticals for MBI, in the diagnosis of local disease recurrence in patients with BC. The main limitation of MBI using conventional gamma-cameras is the low sensitivity for small BCs. The recent development of hybrid single photon emission computed tomography/computed tomography devices and especially of high-resolution specific breast cameras can improve the detection rate of sub-centimetric malignant lesions. Nevertheless, probably only the large availability of dedicated cameras will allow the clinical acceptance of MBI as useful complementary diagnostic technique in BC recurrence. The possible role of MBI with specific cameras in monitoring the local response of BC to neoadjuvant chemotherapy is also briefly discussed. PMID:24322791

  7. Novalike Cataclysmic Variables are Significant Radio Emitters

    CERN Document Server

    Coppejans, Deanne L; Miller-Jones, James C A; Rupen, Michael P; Knigge, Christian; Sivakoff, Gregory R; Groot, Paul J

    2015-01-01

    Radio emission from non-magnetic cataclysmic variables (CVs, accreting white dwarfs) could allow detailed studies of outflows and possibly accretion flows in these nearby, numerous and non-relativistic compact accretors. Up to now, however, very few CVs have been detected in the radio. We have conducted a VLA pilot survey of four close and optically-bright novalike CVs at 6 GHz, detecting three, and thereby doubling the number of radio detections of these systems. RW Sex, V603 Aql and the old nova TT Ari were detected in both of the epochs, while V1084 Her was not detected (to a $3\\sigma$ upper-limit of 7.8 $\\mu\\rm{Jy}\\,\\rm{beam}^{-1}$). These observations clearly show that the sensitivity of previous surveys was typically too low to detect these objects and that non-magnetic CVs can indeed be significant radio emitters. The three detected sources show a range of properties, including flaring and variability on both short ($\\sim$200 s) and longer-term (days) time-scales, as well as circular polarization level...

  8. Fabrication of arrayed glassy carbon field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Sohda, Y.; Tanenbaum, D.M.; Turner, S.W.; Craighead, H.G. [School of Engineering and Applied Physics, Cornell University, Ithaca, New York 14853 (United States)

    1997-03-01

    Glassy carbon has desirable properties for electron field emission such as surface inertness, electrical conductivity, and thermal stability. In addition, a uniform thick substrate with a polished surface is easily obtainable. This enables one to apply large scale integrated circuit processing for fabricating arrayed tips. By using oxygen reactive ion etching, cusps over 3.5 {mu}m in height and 2.5 {mu}m in base diameter are fabricated with a tip radius of under 10 nm. The process is assisted by the formation of a layer of etch products which protects the newly forming tip from bending and over etching. The field emission current up to 50 {mu}A from the glassy carbon tips is obtained by applying high voltage to a mesh anode. The current which passed through the mesh anode is collected at another electrode and measured. The Fowler{endash}Nordheim plot suggests the existence of nm scale structure on the tip. This favorable result indicates glassy carbon substrate is a good substrate for field emitter arrays. {copyright} {ital 1997 American Vacuum Society.}

  9. Tungsten band edge absorber/emitter based on a monolayer of ceramic microspheres.

    Science.gov (United States)

    Dyachenko, P N; do Rosário, J J; Leib, E W; Petrov, A Yu; Störmer, M; Weller, H; Vossmeyer, T; Schneider, G A; Eich, M

    2015-09-21

    We report on a band edge absorber/emitter design for high-temperature applications based on an unstructured tungsten substrate and a monolayer of ceramic microspheres. The absorber was fabricated as a monolayer of ZrO(2) microparticles on a tungsten layer with a HfO(2) nanocoating. The band edge of the absorption is based on critically coupled microsphere resonances. It can be tuned from visible to near-infrared range by varying the diameter of the microparticles. The absorption properties were found to be stable up to 1000°C. PMID:26406752

  10. High-throughput realization of an infrared selective absorber/emitter by DUV microsphere projection lithography.

    Science.gov (United States)

    Bonakdar, Alireza; Rezaei, Mohsen; Dexheimer, Eric; Mohseni, Hooman

    2016-01-22

    In this paper, we present a low-cost and high-throughput nanofabrication method to realize metasurfaces that have selective absorption/emission in the mid-infrared region of the electromagnetic spectrum. We have developed DUV projection lithography to produce arbitrary patterns with sub-80 nm feature sizes. As examples of practical applications, we experimentally demonstrate structures with single and double spectral absorption/emission features, and in close agreement with numerical simulation. The fundamental mechanism of perfect absorption is discussed as well. Selective infrared absorbers/emitters are critical elements in realizing efficient thermophotovoltaic cells and high-performance biosensors. PMID:26650855

  11. High-throughput realization of an infrared selective absorber/emitter by DUV microsphere projection lithography

    Science.gov (United States)

    Bonakdar, Alireza; Rezaei, Mohsen; Dexheimer, Eric; Mohseni, Hooman

    2016-01-01

    In this paper, we present a low-cost and high-throughput nanofabrication method to realize metasurfaces that have selective absorption/emission in the mid-infrared region of the electromagnetic spectrum. We have developed DUV projection lithography to produce arbitrary patterns with sub-80 nm feature sizes. As examples of practical applications, we experimentally demonstrate structures with single and double spectral absorption/emission features, and in close agreement with numerical simulation. The fundamental mechanism of perfect absorption is discussed as well. Selective infrared absorbers/emitters are critical elements in realizing efficient thermophotovoltaic cells and high-performance biosensors.

  12. Emitter Design and Numerical Simulation Based on the Extenics Theory

    Directory of Open Access Journals (Sweden)

    Jiang Fan

    2014-05-01

    Full Text Available In order to improve the performance of emitter, the extenics theory is introduced, whose divergent thinking is used to resolve the conflict of anti-clogging and energy dissipation and a new structure is proposed. The wide triangular areas are designed to reduce the flow rate behind of the each orifice and be easy to precipitation of impurities. The orifices are set to gradually decrease water kinetic energy and the flow channel is designed to be dismantle. The numerical simulation technology is used to analyze the internal flow field of emitter, the flow field results show that the improved emitter has great effect of energy dissipation and anti-clogging. As the same time, the structure of emitter is optimized and L1 = 31 mm, L2 = 21 mm, L3 = 8 mm and L4 = 5 mm are the optimization size values.

  13. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  14. Nanostructure-induced distortion in single-emitter microscopy

    CERN Document Server

    Lim, Kangmook; Fourkas, John; Shapiro, Benjamin; Waks, Edo

    2016-01-01

    Single-emitter microscopy has emerged as a promising method of imaging nanostructures with nanoscale resolution. This technique uses the centroid position of an emitters far-field radiation pattern to infer its position to a precision that is far below the diffraction limit. However, nanostructures composed of high-dielectric materials such as noble metals can distort the far-field radiation pattern. Nanoparticles also exhibit a more complex range of distortions, because in addition to introducing a high dielectric surface, they also act as efficient scatterers. Thus, the distortion effects of nanoparticles in single-emitter microscopy remains poorly understood. Here we demonstrate that metallic nanoparticles can significantly distort the accuracy of single-emitter imaging at distances exceeding 300 nm. We use a single quantum dot to probe both the magnitude and the direction of the metallic nanoparticle-induced imaging distortion and show that the diffraction spot of the quantum dot can shift by more than 35...

  15. Optimization of Metamaterial Selective Emitters for Use in Thermophotovoltaic Applications

    Science.gov (United States)

    Pfiester, Nicole A.

    The increasing costs of fossil fuels, both financial and environmental, has motivated many to look into sustainable energy sources. Thermophotovoltaics (TPVs), specialized photovoltaic cells focused on the infrared range, offer an opportunity to achieve both primary energy capture, similar to traditional photovoltaics, as well as secondary energy capture in the form of waste heat. However, to become a feasible energy source, TPV systems must become more efficient. One way to do this is through the development of selective emitters tailored to the bandgap of the TPV diode in question. This thesis proposes the use of metamaterial emitters as an engineerable, highly selective emitter that can withstand the temperatures required to collect waste heat. Metamaterial devices made of platinum and a dielectric such as alumina or silicon nitride were initially designed and tested as perfect absorbers. High temperature robustness testing demonstrates the device's ability to withstand the rigors of operating as a selective emitter.

  16. Absolute beam emittance measurements at RHIC using ionization profile monitors

    Energy Technology Data Exchange (ETDEWEB)

    Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Connolly, R [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Summers, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-08-15

    In the past, comparisons between emittance measurements obtained using ionization profile monitors, Vernier scans (using as input the measured rates from the zero degree counters, or ZDCs), the polarimeters and the Schottky detectors evidenced significant variations of up to 100%. In this report we present studies of the RHIC ionization profile monitors (IPMs). After identifying and correcting for two systematic instrumental errors in the beam size measurements, we present experimental results showing that the remaining dominant error in beam emittance measurements at RHIC using the IPMs was imprecise knowledge of the local beta functions. After removal of the systematic errors and implementation of measured beta functions, precise emittance measurements result. Also, consistency between the emittances measured by the IPMs and those derived from the ZDCs was demonstrated.

  17. Transverse emittance measurement at REGAE via a solenoid scan

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, Max

    2012-12-15

    The linear accelerator REGAE at DESY produces short and low charged electron bunches, on the one hand to resolve the excitation transitions of atoms temporally by pump probe electron diffraction experiments and on the other hand to investigate principal mechanisms of laser plasma acceleration. For both cases a high quality electron beam is required. A quantity to rate the beam quality is the beam emittance. In the course of this thesis transverse emittance measurements by a solenoid scan could be realized and beyond that an improved theoretical description of a solenoid was successful. The foundation of emittance measurements are constituted by theoretical models which describe the envelope of a beam. Two different models were derived. The first is an often used model to determine the transverse beam emittance without considering space charge effects. More interesting and challenging was the development of an envelope model taking space charge effects into account. It is introduced and cross checked with measurements and simulations.

  18. CSR-induced emittance growth in achromats: Linear formalism revisited

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.

    2015-09-11

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  19. Emission Characteristics of Ion-Implanted Silicon Emitter Tips

    Science.gov (United States)

    Hirano, Takayuki; Kanemaru, Seigo; Tanoue, Hisao; Itoh, Junji

    1995-12-01

    An ion implantation technique has been applied to control the energy band structure of Si field-emitter tip surface. B+ or P+ ions were implanted after fabrication of a gated emitter structure. No changes in emitter structure were observed after ion implantation and successive annealing at 800° C. Current-voltage ( I-V ) characteristics of n, p, p/n and n/p emitter tips were measured: p/n indicates an n-type tip with B+ ions implanted into the tip surface. It was found from the experimental results that n and p/n tips had I-V characteristics in agreement with the Fowler-Nordheim theory. The p and n/p tips, on the other hand, exhibited a current saturation property in high electric field. The present saturation mechanism is explained by considering the energy band structure of the tip surface.

  20. Attribute measure recognition approach and its applications to emitter recognition

    Institute of Scientific and Technical Information of China (English)

    GUAN Xin; HE You; YI Xiao

    2005-01-01

    This paper studies the emitter recognition problem. A new recognition method based on attribute measure for emitter recognition is put forward. The steps of the method are presented. The approach to determining the weight coefficient is also discussed. Moreover, considering the temporal redundancy of emitter information detected by multi-sensor system, this new recognition method is generalized to multi-sensor system. A method based on the combination of attribute measure and D-S evidence theory is proposed. The implementation of D-S reasoning is always restricted by basic probability assignment function. Constructing basic probability assignment function based on attribute measure is presented in multi-sensor recognition system. Examples of recognizing the emitter purpose and system are selected to demonstrate the method proposed. Experimental results show that the performance of this new method is accurate and effective.

  1. Transverse Emittance Measurement and Preservation at the LHC

    CERN Document Server

    AUTHOR|(CDS)2082907

    The Large Hadron Collider (LHC) at CERN is a high energy storage ring that provides proton and heavy ion collisions to study fundamental particle physics. The luminosity production is closely linked to emittance preservation in the accelerator. The transverse emittance is the phase space density of the beam and should be conserved when the particle beam is transformed through the accelerator. Perturbing effects, however, can lead to emittance increase and hence luminosity degradation. Measuring the emittance growth is a complex task with high intensity beams and changing energies. The machine optics and the transverse beam size have to be measured as accurately as possible. Beta function measurements with k-modulation will be discussed. With this method the quadrupole focussing strength is varied and the resulting tune change is traced to determine the beta function at the quadrupole. A new k-modulation measurement tool was developed for the LHC. The fully automatic and online measurement system takes constra...

  2. Recent developments of low-emittance electron gun for accelerator

    International Nuclear Information System (INIS)

    Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R and D effort is 'accelerated' by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed. (author)

  3. Beam Emittance Measurement for PLS-II Linac

    CERN Document Server

    Lee, Byung-Joon; Park, Chong do; Chunjarean, SomJai; Kim, Changbum

    2016-01-01

    The PLS-II has a 100 MeV pre-injector for the 3 GeV Linac. A thermionic gun produces electron charge of 200 pC with a bunch duration of 500 ps by a 250 ps triggering pulser. At the pre-injector, one of the most important beam parameters to identify the beam quality is a transverse emittance of electron bunches. Therefore we measure the beam emittance and twiss functions at 100 MeV in order to match the beam optics to beam transport line and go through it to the storage ring. To get the transverse emittance measurement, well-known technique, quadrupole scan, is used at the pre-injector. The emittance were 0.591 mm-mrad in horizontal and 0.774 mm-mrad in vertical direction.

  4. Innovative energy efficient low-voltage electron beam emitters

    International Nuclear Information System (INIS)

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates

  5. Intelligent Variable Emittance Panels Using New, ?True? Solid Electrolyte Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This firm has, in ongoing work in collaboration with the Air Force, NASA and JPL, developed a unique Variable Emittance technology based on the electrochromism of...

  6. Beam dynamics in rf guns and emittance correction techniques

    Science.gov (United States)

    Serafini, Luca

    1994-02-01

    In this paper we present a general review of beam dynamics in a laser-driven rf gun. The peculiarity of such an accelerating structure versus other conventional multi-cell linac structures is underlined on the basis of the Panofsky-Wenzel theorem, which is found to give a theoretical background for the well known Kim's model. A basic explanation for some proposed methods to correct rf induced emittance growth is also derived from the theorem. We also present three emittance correction techniques for the recovery of space-charge induced emittance growth, namely the optimum distributed disk-like bunch technique, the use of rf spatial harmonics to correct spherical aberration induced by space charge forces and the technique of emittance filtering by clipping the electron beam. The expected performances regarding the beam quality achievable with different techniques, as predicted by scaling laws and simulations, are analyzed, and, where available, compared to experimental results.

  7. Emittance of TD-NiCr after simulated reentry

    Science.gov (United States)

    Clark, R. K.; Dicus, D. L.; Lisagor, W. B.

    1978-01-01

    The effects of simulated reentry heating on the emittance of TD-NiCr were investigated. Groups of specimens with three different preconditioning treatments were exposed to 6, 24, and 30 half-hour simulated reentry exposure cycles in a supersonic arc tunnel at each of three conditions intended to produce surface temperatures of 1255, 1365, and 1475 K. Emittance was determined at 1300 K on specimens which were preconditioned only and specimens after completion of reentry simulation exposure. Oxide morphology and chemistry were studied by scanning electron microscopy and X-ray diffraction analysis. A consistent relationship was established between oxide morphology and total normal emittance. Specimens with coarser textured oxides tended to have lower emittances than specimens with finer textured oxides.

  8. CSR-induced emittance growth in achromats: Linear formalism revisited

    Science.gov (United States)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  9. A Program to Generate a Particle Distribution from Emittance Measurements

    CERN Document Server

    Bouma, DS; Lallement, JB

    2010-01-01

    We have written a program to generate a particle distribution based on emittance measurements in x-x’ and y-y’. The accuracy of this program has been tested using real and constructed emittance measurements. Based on these tests, the distribution generated by the program can be used to accurately simulate the beam in multi-particle tracking codes, as an alternative to a Gaussian or uniform distribution.

  10. Internal emitter limits for iodine, radium and radon daughters

    Energy Technology Data Exchange (ETDEWEB)

    Schlenker, R.A.

    1984-08-15

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (/sup 131/I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables.

  11. Study of ultra-low emittance design for SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M. -H.; Huang, X.; Safranek, J.; /SLAC

    2015-09-17

    Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now, to further enhance the performance of SPEAR3, we are looking into the possibility of converting SPEAR3 to an ultra-low emittance storage ring within its site constraint.

  12. Internal emitter limits for iodine, radium and radon daughters

    International Nuclear Information System (INIS)

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (131I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables

  13. A Novel Depletion-Mode MOS Gated Emitter Shorted Thyristor

    Institute of Scientific and Technical Information of China (English)

    张鹤鸣; 戴显英; 张义门; 马晓华; 林大松

    2000-01-01

    A Novel MOS-gated thyristor, depletion-mode MOS gated emitter shorted thyristor (DMST),and its two structures are proposed. In DMST,the channel of depletion-mode MOS makes the thyristor emitter-based junction inherently short. The operation of the device is controlled by the interruption and recovery of the depletion-mode MOS P channel. The perfect properties have been demonstrated by 2-D numerical simulations and the tests on the fabricated chips.

  14. Lambertian thermal emitter based on plasmonic enhanced absorption.

    Science.gov (United States)

    Wang, Chih-Ming; Tsai, Din Ping

    2016-08-01

    In this paper, a narrow band thermal emission at 10 μm is demonstrated using a one dimensional metasurface. The proposed metasurface structure provides magnetic resonance mode that enhances the phonon absorption of SiO2. The proposed metasurface thermal emitter shows a Lambertian distribution. Additionally, 5.8-folds enhancement of emissivity is achieved by optimizing the cavity thickness of the metasurfaces. This type of thermal emitter will be useful for IR sensing applications. PMID:27505801

  15. Optimization of the emittance of electrons (positrons) storage rings

    International Nuclear Information System (INIS)

    An important parameter of the source characteristics of a synchrotron radiation facility, is the beam emittance. The general structure presently adopted, is of the achromatic arc, or adapted dispersion type. This structure allows analytical treatment of dispersion and β function in the arcs, and then, the minimization of the dimension invariant. Practical formulae are given, allowing scaling of momentum compaction factor, minimum emittance limit and β value in the magnets. Limitations in chromaticity correction possibilities are also discussed

  16. Ab initio alpha-alpha scattering

    CERN Document Server

    Elhatisari, Serdar; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G

    2015-01-01

    Processes involving alpha particles and alpha-like nuclei comprise a major part of stellar nucleosynthesis and hypothesized mechanisms for thermonuclear supernovae. In an effort towards understanding alpha processes from first principles, we describe in this letter the first ab initio calculation of alpha-alpha scattering. We use lattice effective field theory to describe the low-energy interactions of nucleons and apply a technique called the adiabatic projection method to reduce the eight-body system to an effective two-cluster system. We find good agreement between lattice results and experimental phase shifts for S-wave and D-wave scattering. The computational scaling with particle number suggests that alpha processes involving heavier nuclei are also within reach in the near future.

  17. Thin Emitter Structure Improved Turn-on Characteristics in RSD

    Institute of Scientific and Technical Information of China (English)

    LIANG Lin; YU Yuehui; ZHOU Yuming; WANG Lu

    2008-01-01

    The thin emitter structure was introduced into reversely switched dynistor (RSD) to improve its turn-on characteristics. According to the analysis of turn-on condition, thin emitter structure is capable of reducing the extraction action for the triggering plasma layer P1 during turn-on process, and satisfying the requirement that triggering electric charge cannot be exhausted and therefore enables RSD to turn on uniformly. The on-state thin emitter RSD was equivalent to an asymmetric pin diode model. The simulation result shows that the forward voltage drop of RSD falls with the decrease of doping dose in p+-emitter in a certain range, and when the doping concentration is extremely low, the decrease of the width of p+-emitter can obtain a low forward voltage drop. Thin emitter RSD chips were made by sintering Al on n-Si. The test result shows that their turn-on process is uniform and the voltage drop is 7.5V when the peak conversion current is 5500A.

  18. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    Directory of Open Access Journals (Sweden)

    Guag Joshua W

    2011-06-01

    Full Text Available Abstract Background The objective of this study is to investigate electromagnetic compatibility (EMC of implantable neurostimulators with the emissions from radio frequency identification (RFID emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  19. Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter

    Science.gov (United States)

    Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos

    2015-11-01

    This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.

  20. Diffuse Ly$\\alpha$ Halos around Galaxies at $z=2.2-6.6$: Implications for Galaxy Formation and Cosmic Reionization

    CERN Document Server

    Momose, Rieko; Nakajima, Kimihiko; Ono, Yoshiaki; Shibuya, Takatoshi; Shimasaku, Kazuhiro; Yuma, Suraphong; Mori, Masao; Umemura, Masayuki

    2014-01-01

    We present diffuse Ly$\\alpha$ halos (LAHs) identified in the composite Subaru narrowband images of $100-3600 $ Ly$\\alpha$ emitters (LAEs) at $z=2.2$, $3.1$, $3.7$, $5.7$, and $6.6$. First, we carefully examine potential artifacts mimicking LAHs that include a large-scale point-spread function (PSF) made by instrumental and atmospheric effects. Based on our critical test with composite images of non-LAE samples whose narrowband-magnitude and source-size distributions are the same as our LAE samples, we confirm that no artifacts can produce a diffuse extended feature similar to our LAHs. After this test, we measure the scale lengths of exponential profile for the LAHs estimated from our $z=2.2-6.6$ LAE samples of $L_{\\rm Ly\\alpha}\\gtrsim 2\\times 10^{42}$ erg s$^{-1}$. We obtain the scale lengths of $\\simeq 5-10$ kpc at $z=2.2-5.7$, and find no evolution of scale lengths in this redshift range beyond our measurement uncertainties. Combining this result and the previously-known UV-continuum size evolution, we inf...

  1. Silicon Carbide Emitter Turn-Off Thyristor

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2008-01-01

    Full Text Available A novel MOS-controlled SiC thyristor device, the SiC emitter turn-off thyristor (ETO is a promising technology for future high-voltage switching applications because it integrates the excellent current conduction capability of a SiC thyristor with a simple MOS-control interface. Through unity-gain turn-off, the SiC ETO also achieves excellent Safe Operation Area (SOA and faster switching speeds than silicon ETOs. The world's first 4.5-kV SiC ETO prototype shows a forward voltage drop of 4.26 V at 26.5 A/cm2 current density at room and elevated temperatures. Tested in an inductive circuit with a 2.5 kV DC link voltage and a 9.56-A load current, the SiC ETO shows a fast turn-off time of 1.63 microseconds and a low 9.88 mJ turn-off energy. The low switching loss indicates that the SiC ETO could operate at about 4 kHz if 100 W/cm2 conduction and the 100 W/cm2 turn-off losses can be removed by the thermal management system. This frequency capability is about 4 times higher than 4.5-kV-class silicon power devices. The preliminary demonstration shows that the SiC ETO is a promising candidate for high-frequency, high-voltage power conversion applications, and additional developments to optimize the device for higher voltage (>5 kV and higher frequency (10 kHz are needed.

  2. Remote system for measurement of radon alpha emitter for population safety guards

    International Nuclear Information System (INIS)

    The objective of this research project is to study the OSL properties for high doses of dosemeters traditionally applied in thermoluminescent dosimetry (TL), as CaF2: Dy (TLD 200) and CaF2: Mn (TLD 400), and thus verify the applicability of OSL technique in high-dose dosimetry

  3. Ab initio alpha-alpha scattering

    Science.gov (United States)

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A.; Luu, Thomas; Meißner, Ulf-G.

    2015-12-01

    Processes such as the scattering of alpha particles (4He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei—nuclei with even and equal numbers of protons and neutrons—is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the ‘adiabatic projection method’ to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  4. Ab initio alpha-alpha scattering.

    Science.gov (United States)

    Elhatisari, Serdar; Lee, Dean; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G

    2015-12-01

    Processes such as the scattering of alpha particles ((4)He), the triple-alpha reaction, and alpha capture play a major role in stellar nucleosynthesis. In particular, alpha capture on carbon determines the ratio of carbon to oxygen during helium burning, and affects subsequent carbon, neon, oxygen, and silicon burning stages. It also substantially affects models of thermonuclear type Ia supernovae, owing to carbon detonation in accreting carbon-oxygen white-dwarf stars. In these reactions, the accurate calculation of the elastic scattering of alpha particles and alpha-like nuclei--nuclei with even and equal numbers of protons and neutrons--is important for understanding background and resonant scattering contributions. First-principles calculations of processes involving alpha particles and alpha-like nuclei have so far been impractical, owing to the exponential growth of the number of computational operations with the number of particles. Here we describe an ab initio calculation of alpha-alpha scattering that uses lattice Monte Carlo simulations. We use lattice effective field theory to describe the low-energy interactions of protons and neutrons, and apply a technique called the 'adiabatic projection method' to reduce the eight-body system to a two-cluster system. We take advantage of the computational efficiency and the more favourable scaling with system size of auxiliary-field Monte Carlo simulations to compute an ab initio effective Hamiltonian for the two clusters. We find promising agreement between lattice results and experimental phase shifts for s-wave and d-wave scattering. The approximately quadratic scaling of computational operations with particle number suggests that it should be possible to compute alpha scattering and capture on carbon and oxygen in the near future. The methods described here can be applied to ultracold atomic few-body systems as well as to hadronic systems using lattice quantum chromodynamics to describe the interactions of

  5. Emittance and Phase Space Tomography for the Fermilab Linac

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, F.G.G.; Johnstone, C.; Kobilarcik, T.; Koizumi, G.M.; Moore, C.D.; /Fermilab; Newhart, D.L.; /Fermilab

    2012-05-01

    The Fermilab Linac delivers a variable intensity, 400-MeV beam to the MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a deconvolution of the profile data. Preliminary measurements using this diagnostic section are reported here. These data represent a first-pass measurement of the Linac emittance based on various techniques. It is clear that the most accurate representation of the emittance is given by the 3-profile approach. Future work will entail minimizing the beam spot size on MW5 to test and possibly improve the accuracy of the 2-profile approach. The 95% emittance is {approx} 18{pi} in the vertical and {approx} 13{pi} in the horizontal, which is especially larger than anticipated - 8-10{pi} was expected. One possible explanation is that the entire Linac pulse is extracted into the MTA beamline and during the first few microseconds, the feed forward and RF regulation are not stable. This may result in a larger net emittance observed versus beam injected into Booster, where the leading part of the Linac beam pulse is chopped. Future studies will clearly entail a measurement of the emittance vs. pulse length. One additional concern is that the Linac phase space is most likely aperture-defined and non-elliptical in nature. A non-elliptical phase-space determination would require a more elaborate analysis and provide another explanation of the

  6. Faddeev calculation of 3 alpha and alpha alpha Lambda systems using alpha alpha resonating-group method kernel

    CERN Document Server

    Fujiwara, Y; Kohno, M; Suzuki, Y; Baye, D; Sparenberg, J M

    2004-01-01

    We carry out Faddeev calculations of three-alpha (3 alpha) and two-alpha plus Lambda (alpha alpha Lambda) systems, using two-cluster resonating-group method kernels. The input includes an effective two-nucleon force for the alpha alpha resonating-group method and a new effective Lambda N force for the Lambda alpha interaction. The latter force is a simple two-range Gaussian potential for each spin-singlet and triplet state, generated from the phase-shift behavior of the quark-model hyperon-nucleon interaction, fss2, by using an inversion method based on supersymmetric quantum mechanics. Owing to the exact treatment of the Pauli-forbidden states between the clusters, the present three-cluster Faddeev formalism can describe the mutually related, alpha alpha, 3 alpha and alpha alpha Lambda systems, in terms of a unique set of the baryon-baryon interactions. For the three-range Minnesota force which describes the alpha alpha phase shifts quite accurately, the ground-state and excitation energies of 9Be Lambda are...

  7. Optimisation study of {alpha}-cyclotron production of At-211/Po-211g for high-LET metabolic radiotherapy purposes

    Energy Technology Data Exchange (ETDEWEB)

    Groppi, F. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy)]. E-mail: flavia.groppi@mi.infn.it; Bonardi, M.L. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy); Birattari, C. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy); Menapace, E. [ENEA, Division for Advanced Physics Technologies, via Don Fiammelli 2, I-40128 Bologna (Italy); Abbas, K. [Institute for Health and Consumer Protection, IHCP, JRC-Ispra, via E. Fermi, I-21020 Varese (Italy); Holzwarth, U. [Institute for Health and Consumer Protection, IHCP, JRC-Ispra, via E. Fermi, I-21020 Varese (Italy); Alfarano, A. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy); Institute for Health and Consumer Protection, IHCP, JRC-Ispra, via E. Fermi, I-21020 Varese (Italy); Morzenti, S. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy); Zona, C. [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, I-20090 Segrate, Milan (Italy); Alfassi, Z.B. [Department of Nuclear Engineering, Ben Gurion University of Negev, Beer-Sheva, Il-84105 (Israel)

    2005-12-01

    The production of no-carrier-added (NCA) {alpha}-emitter {sup 211}At/{sup 211g}Po radionuclides for high-LET targeted radiotherapy and immunoradiotherapy, through the {sup 209}Bi({alpha},2n) reaction, together with the required wet radiochemistry and radioanalytical quality controls carried out at LASA is described, through dedicated irradiation experiments at the MC-40 cyclotron of JRC-Ispra. The amount of both the {gamma}-emitter {sup 210}At and its long half-lived {alpha}-emitting daughter {sup 210}Po is optimised and minimised by appropriate choice of energy and energy loss of {alpha} particle beam. The measured excitation functions for production of the main radioisotopic impurity {sup 210}At{yields}{sup 210}Po are compared with theoretical predictions from model calculations performed at ENEA.

  8. Effect of water alpha radiolysis on the spent nuclear fuel UO2 matrix alteration

    International Nuclear Information System (INIS)

    Leaching experiments with solution renewal were carried out on UO2 pellets doped with alpha emitters (238/239Pu) to quantify the impact of alpha irradiation on UO2 matrix alteration. Three batches of doped UO2 pellets with different alpha flux levels were studied as well as spent fuel fragments. Interim storage in air of UO2 pellets doped with alpha emitters results in variations of the UO2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO2 pellet batches and spent fuel. However, leaching experiments performed in deaerated media after annealing the samples and pre-leaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the flux at the UO2/water interface. (authors)

  9. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    Energy Technology Data Exchange (ETDEWEB)

    Houck, T L; Brown, C G; Ong, M M; Paul, A C; Wargo, P E; Zentler, J M

    2006-08-11

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented.

  10. Field emitter arrays for plasma and microwave source applications

    Science.gov (United States)

    Jensen, K. L.

    1999-05-01

    Field emitter arrays (FEAs) stand to strongly impact device performance when physical size, weight, power consumption, beam current, and/or high pulse repetition frequencies are an issue. FEAs are capable of instant ON/OFF performance, high brightness, high current density, large transconductance to capacitance ratio, and low voltage operation characteristics. Advanced microwave power tubes, and in particular, inductive output amplifiers, are by far the most technically challenging use to date. Other important uses include, e.g., electron sources for micropropulsion systems-Hall thrusters-and tethers for satellites, and (the most widely pursued application) field emission displays. The characteristics of field emitters that make them attractive to such applications shall be surveyed. A thorough analytical model of a field emitter array, beginning with a review of the nature of field emission and continuing with an analytical model of a single emitter and the operation of an array of emitters, shall be presented. In particular, attention shall be directed towards those features of FEAs that render them attractive as cold cathode candidates for electron beam generation. Tip characteristics, such as emission distribution, and array operation, such as space charge effects, will be analyzed in the context of the model. Finally, restricting attention to microwave applications, the performance of a tapered-helix inductive output amplifier to highlight the advantages of high frequency emission gating of the electron beam in a power tube shall be investigated.

  11. Quantitative Single-Particle Digital Autoradiography with α-Particle Emitters for Targeted Radionuclide Therapy using the iQID Camera

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Brian W.; Frost, Sophia; Frayo, Shani; Kenoyer, Aimee L.; Santos, E. B.; Jones, Jon C.; Green, Damian J.; Hamlin, Donald K.; Wilbur, D. Scott; Fisher, Darrell R.; Orozco, Johnnie J.; Press, Oliver W.; Pagel, John M.; Sandmaier, B. M.

    2015-07-01

    Abstract Alpha emitting radionuclides exhibit a potential advantage for cancer treatments because they release large amounts of ionizing energy over a few cell diameters (50–80 μm) causing localized, irreparable double-strand DNA breaks that lead to cell death. Radioimmunotherapy (RIT) approaches using monoclonal antibodies labeled with alpha emitters may inactivate targeted cells with minimal radiation damage to surrounding tissues. For accurate dosimetry in alpha-RIT, tools are needed to visualize and quantify the radioactivity distribution and absorbed dose to targeted and non-targeted cells, especially for organs and tumors with heterogeneous radionuclide distributions. The aim of this study was to evaluate and characterize a novel single-particle digital autoradiography imager, iQID (ionizing-radiation Quantum Imaging Detector), for use in alpha-RIT experiments. Methods: The iQID camera is a scintillator-based radiation detection technology that images and identifies charged-particle and gamma-ray/X-ray emissions spatially and temporally on an event-by-event basis. It employs recent advances in CCD/CMOS cameras and computing hardware for real-time imaging and activity quantification of tissue sections, approaching cellular resolutions. In this work, we evaluated this system’s characteristics for alpha particle imaging including measurements of spatial resolution and background count rates at various detector configurations and quantification of activity distributions. The technique was assessed for quantitative imaging of astatine-211 (211At) activity distributions in cryosections of murine and canine tissue samples. Results: The highest spatial resolution was measured at ~20 μm full width at half maximum (FWHM) and the alpha particle background was measured at a rate of (2.6 ± 0.5) × 10–4 cpm/cm2 (40 mm diameter detector area). Simultaneous imaging of multiple tissue sections was performed using a large-area iQID configuration (ø 11.5 cm

  12. Quantifying, Assessing, and Mitigating Methane Emissions from Super-emitters in the Oil and Gas Supply Chain

    Science.gov (United States)

    Lyon, David Richard

    Methane emissions from the oil and gas (O&G) supply chain reduce potential climate benefits of natural gas as a replacement for other fossil fuels that emit more carbon dioxide per energy produced. O&G facilities have skewed emission rate distributions with a small fraction of sites contributing the majority of emissions. Knowledge of the identity and cause of these high emission facilities, referred to as super-emitters or fat-tail sources, is critical for reducing supply chain emissions. This dissertation addresses the quantification of super-emitter emissions, assessment of their prevalence and relationship to site characteristics, and mitigation with continuous leak detection systems. Chapter 1 summarizes the state of the knowledge of O&G methane emissions. Chapter 2 constructs a spatially-resolved emission inventory to estimate total and O&G methane emissions in the Barnett Shale as part of a coordinated research campaign using multiple top-down and bottom-up methods to quantify emissions. The emission inventory accounts for super-emitters with two-phase Monte Carlo simulations that combine site measurements collected with two approaches: unbiased sampling and targeted sampling of super-emitters. More comprehensive activity data and the inclusion of super-emitters, which account for 19% of O&G emissions, produces a emission inventory that is not statistically different than top-down regional emission estimates. Chapter 3 describes a helicopter-based survey of over 8,000 well pads in seven basins with infrared optical gas imaging to assess high emission sources. Four percent of sites are observed to have high emissions with over 90% of observed sources from tanks. The occurrence of high emissions is weakly correlated to site parameters and the best statistical model explains only 14% of variance, which demonstrates that the occurrence of super-emitters is primarily stochastic. Chapter 4 presents a Gaussian dispersion model for optimizing the placement of

  13. CriticalEd

    DEFF Research Database (Denmark)

    Kjellberg, Caspar Mølholt; Meredith, David

    2014-01-01

    such as Sibelius or Finale. It was hypothesized that it would be possible to develop a Sibelius plug-in, written in Manuscript 6, that would improve the critical editing work flow, but it was found that the capabilities of this scripting language were insufficient. Instead, a 3-part system was designed and built......, consisting of a Sibelius plug-in, a cross-platform application, called CriticalEd, and a REST-based solution, which handles data storage/retrieval. A prototype has been tested at the Danish Centre for Music Publication, and the results suggest that the system could greatly improve the efficiency...

  14. Review of alpha_s determinations

    CERN Document Server

    Pich, Antonio

    2013-01-01

    The present knowledge on the strong coupling is briefly summarized. The most precise determinations of alpha_s, at different energies, are reviewed and compared at the Z mass scale, using the predicted QCD running. The impressive agreement achieved between experimental measurements and theoretical predictions constitutes a beautiful and very significant test of Asymptotic Freedom, establishing QCD as the fundamental theory of the strong interaction. The world average value of the strong coupling is found to be alpha_s(M_Z^2)= 0.1186 \\pm 0.0007.

  15. Emittance measurements results with upgraded setup at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Vashchenko, Grygorii; Asova, Galina; Gross, Matthias; Hakobyan, Levon; Isaev, Igor; Ivanisenko, Yevgeniy; Khojoyan, Martin; Klemz, Guido; Krasilnikov, Mikhail; Mahgoub, Mahmoud; Malyutin, Dmitriy; Otevrel, Marek; Petrosyan, Bagrat; Riechter, Dieter; Rimjaem, Sakhorn; Shapovalov, Andrey; Stephan, Frank [DESY, Zeuthen (Germany); Nozdrin, Mikhail [JINR, Dubna (Russian Federation); Templin, Horst-Ingo; Will, Ingo [MBI, Berlin (Germany)

    2012-07-01

    The photo injector test facility at DESY, Zeuthen site, PITZ develops and characterizes photoelectron sources for linac driven free electron lasers (FELs) such as FLASH and the European XFEL. The main goal of the PITZ is to obtain electron beams with low transverse normalize emittance which is necessary for the successful operation of SASE FEL. Major parts of the facility - gun and booster cavities, photocathode laser system were upgraded in 2010 in order to improve the photo injector performance. A slit technique is used at PITZ to reconstruct the transverse phase space of the electron beam. Many machine parameters were tuned to optimize the beam emittance for a wide range of the bunch charge - from 20 pC to 2 nC. Measured emittance depending on various machine parameters like a gun launching phase, booster gradient, laser spot size on the cathode and main solenoid current is presented.

  16. A Review on Multiple Emitter Location and Signal Parameter Estimation

    Directory of Open Access Journals (Sweden)

    Sandeep Santosh, Karan Sharma

    2013-07-01

    Full Text Available Processing the signals received on an array of sensors for the location of the emitter is of great enough interest to have been treated under many special case assumptions. The general problem considers sensors with arbitrary locations and arbitrary directional characteristics (gain phase polarization in a noise/interference environment of arbitrary covariance matrix. This report is concerned first with the multiple emitter aspect of this problem and second with the generality of solution. A description is given of the multiple signal classification (MUSIC algorithm, which provides asymptotically unbiased estimates of 1 number of incident wavefronts present; 2 directions of arrival (DOA (or emitter locations; 3 strengths and cross correlations among the incident waveforms; 4 noise/interference strength. Examples and comparisons with methods based on maximum likelihood (ML and maximum entropy (ME, as well as conventional beamforming are. included. An example of its use as a multiple frequency estimator operating on time series is included.

  17. Hybrid genetic optimization for design of photonic crystal emitters

    Science.gov (United States)

    Rammohan, R. R.; Farfan, B. G.; Su, M. F.; El-Kady, I.; Reda Taha, M. M.

    2010-09-01

    A unique hybrid-optimization technique is proposed, based on genetic algorithms (GA) and gradient descent (GD) methods, for the smart design of photonic crystal (PhC) emitters. The photonic simulation is described and the granularity of photonic crystal dimensions is considered. An innovative sliding-window method for performing local heuristic search is demonstrated. Finally, the application of the proposed method on two case studies for the design of a multi-pixel photonic crystal emitter and the design of thermal emitter in thermal photovoltaic is demonstrated. Discussion in the report includes the ability of the optimal PhC structures designed using the proposed method, to produce unprecedented high emission efficiencies of 54.5% in a significantly long wavelength region and 84.9% at significantly short wavelength region.

  18. On the measurement of positron emitters with Ge detectors

    Energy Technology Data Exchange (ETDEWEB)

    Peyres, Virginia, E-mail: virginia.peyres@ciemat.e [Ciemat, Laboratorio de Metrologia de Radiaciones Ionizantes, Avda. Complutense 22, Madrid 28040 (Spain); Garcia-Torano, Eduardo [Ciemat, Laboratorio de Metrologia de Radiaciones Ionizantes, Avda. Complutense 22, Madrid 28040 (Spain)

    2011-05-01

    This paper discusses the problems related to the measurement of positron emitters with germanium detectors. Five positron emitters with important applications in nuclear medicine ({sup 22}Na, {sup 18}F, {sup 11}C, {sup 13}N and {sup 68}Ga) have been studied. Measurements and Monte Carlo simulations have been used to determine the optimal conditions of measurement in gamma-ray spectrometry systems. The results obtained indicate that adding adequate absorbers, detection efficiencies are close to those of gamma emitters of similar energy measured in the same conditions, which allows a rapid calibration of a Ge-based spectrometry system. More accurate results are also presented using a detailed Monte Carlo simulation. Comparison to experimental data shows a good agreement.

  19. DC-SC Photoinjector with Low Emittance at Peking University

    CERN Document Server

    Xiang Rong; Hao, J; Huang, Senlin; Lu Xiang Yang; Quan, Shengwen; Zhang, Baocheng; Zhao, Kui

    2005-01-01

    High average power Free Electron Lasers require the high quality electron beams with the low emittance and the sub-picosecond bunches. The design of DC-SC photoinjector, directly combining a DC photoinjector with an SRF cavity, can produce high average current beam with moderate bunch charge and high duty factor. Because of the DC gun, the emittance increases quickly at the beginning, so a carefully design is needed to control that. In this paper, the simulation of an upgraded design has been done to lower the normalized emittance below 1.5mm·mrad. The photoinjector consists of a DC gap and a 2+1/2-cell SRF cavity, and it is designed to produce 4.2 MeV electron beams at 100pC bunch charge and 81.25MHz repetition rate (8 mA average current).

  20. Emittance growth in the DARHT Axis-II Downstream Transport

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Jr., Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Martin E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-14

    Using a particle-in-cell (PIC) code, we investigated the possibilities for emittance growth through the quadrupole magnets of the system used to transport the high-current electron beam from an induction accelerator to the bremsstrahlung converter target used for flash radiography. We found that even highly mismatched beams exhibited little emittance growth (< 6%), which we attribute to softening of their initial hard edge current distributions. We also used this PIC code to evaluate the accuracy of emittance measurements using a solenoid focal scan following the quadrupole magnets. If the beam is round after the solenoids, the simulations indicate that the measurement is highly accurate, but it is substantially inaccurate for elliptical beams

  1. Fully tuneable, Purcell-enhanced solid-state quantum emitters

    Energy Technology Data Exchange (ETDEWEB)

    Petruzzella, M., E-mail: m.petruzzella@tue.nl; Xia, T.; Pagliano, F.; Birindelli, S.; Zobenica, Z.; Fiore, A. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, NL-5600MB Eindhoven (Netherlands); Midolo, L. [Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Li, L. H.; Linfield, E. H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2015-10-05

    We report the full energy control over a semiconductor cavity-emitter system, consisting of single Stark-tunable quantum dots embedded in mechanically reconfigurable photonic crystal membranes. A reversible wavelength tuning of the emitter over 7.5 nm as well as an 8.5 nm mode shift are realized on the same device. Harnessing these two electrical tuning mechanisms, a single exciton transition is brought on resonance with the cavity mode at several wavelengths, demonstrating a ten-fold enhancement of its spontaneous emission. These results open the way to bring several cavity-enhanced emitters mutually into resonance and therefore represent a key step towards scalable quantum photonic circuits featuring multiple sources of indistinguishable single photons.

  2. Emittance measurements for the Illinois/CEBAF polarized electron source

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, B.M.; Cardman, L.S. [Illinois Univ., Urbana, IL (United States); Sinclair, C.K. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

    1995-01-01

    The transverse thermal properties of the electrons photoemitted from GaAs determine the intrinsic beam emittance, an important quantity in applications such as polarized electron sources and high-brightness sources. In this paper, emittance measurements using the Illinois/CEBAF polarized electron source are described. The emittance was measured as a function of both the laser beam spot size and laser wavelength at low currents. The data was used to infer the transverse thermal energy of the electrons photoemitted from GaAs for wavelengths between 514 and 840 nm. Near the bandgap the transverse energy is {approximately}34 meV, a factor of 3 lower than that of the beam from a typical thermionic electron gun. 8 refs., 2 figs.

  3. An extreme [OIII] emitter at $z=3.2$: a low metallicity Lyman continuum source

    CERN Document Server

    de Barros, S; Amorín, R; Castellano, M; Siana, B; Grazian, A; Suh, H; Balestra, I; Vignali, C; Verhamme, A; Zamorani, G; Mignoli, M; Hasinger, G; Comastri, A; Pentericci, L; Pérez-Montero, E; Fontana, A; Giavalisco, M; Gilli, R

    2016-01-01

    [Abridged] We investigate the physical properties of a Lyman continuum emitter candidate at $z=3.212$ with photometric coverage from $U$ to MIPS 24$\\mu$m band and VIMOS/VLT and MOSFIRE/Keck spectroscopy. Investigation of the UV spectrum confirms a direct spectroscopic detection of the Lyman continuum emission with $S/N>5$. Non-zero Ly$\\alpha$ flux at the systemic redshift and high Lyman-$\\alpha$ escape fraction suggest a low HI column density. The weak C and Si low-ionization absorption lines are also consistent with a low covering fraction along the line of sight. The [OIII]$\\lambda\\lambda4959,5007+\\mathrm{H}\\beta$ equivalent width is one of the largest reported for a galaxy at $z>3$ ($\\mathrm{EW}([\\mathrm{OIII}]\\lambda\\lambda4959,5007+\\mathrm{H}\\beta) \\simeq 1600\\AA$, rest-frame) and the NIR spectrum shows that this is mainly due to an extremely strong [OIII] emission. The large observed [OIII]/[OII] ratio ($>10$) and high ionization parameter are consistent with prediction from photoionization models in ca...

  4. Cooperative behavior of quantum dipole emitters coupled to a zero-index nanoscale waveguide

    CERN Document Server

    Sokhoyan, Ruzan

    2015-01-01

    We study cooperative behavior of quantum dipole emitters coupled to a rectangular waveguide with dielectric core and silver cladding. We investigate cooperative emission and inter-emitter entanglement generation phenomena for emitters whose resonant frequencies are near the frequency cutoff of the waveguide, where the waveguide effectively behaves as zero-index metamaterial. We show that coupling emitters to a zero-index waveguide allows one to relax the constraint on precision positioning of emitters for observing inter-emitter entanglement generation and extend the spatial scale at which the superradiance can be observed.

  5. Radiation doses and risks from internal emitters

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, John [Health Protection Agency, Radiation Protection Division, CRCE, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom); Day, Philip [School of Chemistry, University of Manchester, Manchester M13 9PL (United Kingdom)], E-mail: john.harrison@hpa.org.uk, E-mail: philip.day@manchester.ac.uk

    2008-06-01

    This review updates material prepared for the UK Government Committee Examining Radiation Risks from Internal Emitters (CERRIE) and also refers to the new recommendations of the International Commission on Radiological Protection (ICRP) and other recent developments. Two conclusions from CERRIE were that ICRP should clarify and elaborate its advice on the use of its dose quantities, equivalent and effective dose, and that more attention should be paid to uncertainties in dose and risk estimates and their implications. The new ICRP recommendations provide explanations of the calculation and intended purpose of the protection quantities, but further advice on their use would be helpful. The new recommendations refer to the importance of understanding uncertainties in estimates of dose and risk, although methods for doing this are not suggested. Dose coefficients (Sv per Bq intake) for the inhalation or ingestion of radionuclides are published as reference values without uncertainty. The primary purpose of equivalent and effective dose is to enable the summation of doses from different radionuclides and from external sources for comparison with dose limits, constraints and reference levels that relate to stochastic risks of whole-body radiation exposure. Doses are calculated using defined biokinetic and dosimetric models, including reference anatomical data for the organs and tissues of the human body. Radiation weighting factors are used to adjust for the different effectiveness of different radiation types, per unit absorbed dose (Gy), in causing stochastic effects at low doses and dose rates. Tissue weighting factors are used to take account of the contribution of individual organs and tissues to overall detriment from cancer and hereditary effects, providing a simple set of rounded values chosen on the basis of age- and sex-averaged values of relative detriment. While the definition of absorbed dose has the scientific rigour required of a basic physical quantity

  6. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  7. High-efficiency photonic crystal narrowband thermal emitters

    Science.gov (United States)

    Farfan, G. B.; Su, M. F.; Reda Taha, M. M.; El-Kady, I.

    2010-02-01

    Photonic crystals (PhC) are artificial structures fabricated with a periodicity in the dielectric function. This periodic electromagnetic potential results in creation of energy bandgaps where photon propagation is prohibited. PhC structures have promising use in thermal applications if optimized to operate at specific thermal emission spectrum. Here, novel utilization of optimized PhC's in thermal applications is presented. We demonstrate through numerical simulation the modification of the thermal emission spectrum by a metallic photonic crystal (PhC) to create high-efficiency multispectral thermal emitters. These emitters funnel radiation from a broad emission spectrum associated with a Plancklike distribution into a prescribed narrow emission band. A detailed quantitative evaluation of the spectral and power efficiencies of a PhC thermal emitter and its portability across infrared (IR) spectral bands are provided. We show an optimized tungsten PhC with a predominant narrow-band emission profile with an emitter efficiency that is more than double that of an ideal blackbody and ~65-75% more power-efficiency across the IR spectrum. We also report on using optimal three-dimensional Lincoln log photonic crystal (LL-PhC) emitters for thermophotovoltaic (TPV) generation as opposed to using a passive filtering approach to truncate the broadband thermal source emission to match the bandgap of a photovoltaic (PV) cell. The emitter performance is optimized for the 1-2μm PV band using different PhC materials, specifically copper, silver and gold. The use of the proposed PhC in TPV devices can produce significant energy savings not reported before. The optimal design of the PhC geometry is obtained by implementing a variety of optimization methods integrated with artificial intelligence (AI) algorithms.

  8. Beam emittance reduction during operation of Indus-2

    Science.gov (United States)

    Fakhri, Ali Akbar; Kant, Pradeep; Ghodke, A. D.; Singh, Gurnam

    2015-11-01

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed.

  9. Beam emittance reduction during operation of Indus-2

    Energy Technology Data Exchange (ETDEWEB)

    Fakhri, Ali Akbar, E-mail: fakhri@rrcat.gov.in; Kant, Pradeep; Ghodke, A. D.; Singh, Gurnam [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2015-11-15

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed.

  10. Beam emittance reduction during operation of Indus-2

    International Nuclear Information System (INIS)

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed

  11. Beam emittance reduction during operation of Indus-2.

    Science.gov (United States)

    Fakhri, Ali Akbar; Kant, Pradeep; Ghodke, A D; Singh, Gurnam

    2015-11-01

    Indus-2 storage ring is a 2.5 GeV third generation synchrotron radiation source. This source was commissioned using a moderate optics. Beam injection was accomplished using an off momentum electron beam to avoid difficulties faced in storage of beam at 550 MeV. The injection procedure and relevant beam dynamical studies are discussed. The switch over from the moderate optics to low emittance optics is done at 2.5 GeV after storing the electron beam. The procedure evolved to reduce the beam emittance and its implementation during the operation is discussed. PMID:26628127

  12. Emittances Studies at the Fermilab/NICADD Photoinjector Laboratory

    CERN Document Server

    Tikhoplav, Rodion; Melissinos, A C; Regis-Guy Piot, Philippe

    2005-01-01

    The Fermilab/NICADD photoinjector incorporates an L-band rf-gun capable of generating 1-10 nC bunches. The bunches are then accelerated to 16 MeV with a TESLA superconducting cavity. In the present paper we present parametric studies of transverse emittances and energy spread for a various operating points of the electron source (RF-gun E-field, laser length and spot size, and solenoid settings). We especially study the impact, on transverse emittance, of Gaussian and Plateau temporal distribution of the photocathode drive-laser.

  13. Thermal emittance and response time of a cesium antimonide photocathode

    Science.gov (United States)

    Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

    2011-10-01

    Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

  14. Efficient Terahertz Photoconductive Emitters with Improved Electrode Structures

    Institute of Scientific and Technical Information of China (English)

    Ying-Xin Wang; Yi-Jie Niu; Wei Cheng; Zhi-Qiang Li; Zi-Ran Zhao

    2014-01-01

    We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure, which are all modified from a traditional strip line antenna. Numerical simulations and real experiments confirm the good performance of the proposed antennas. An amplitude increase of about 40% is experimentally observed for the terahertz signals generated from the new structures. The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement. Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.

  15. Ultra-Sensitivity Glucose Sensor Based on Field Emitters

    Directory of Open Access Journals (Sweden)

    Song Yinglin

    2009-01-01

    Full Text Available Abstract A new glucose sensor based on field emitter of ZnO nanorod arrays (ZNA was fabricated. This new type of ZNA field emitter-based sensor shows high sensitivity with experimental limit of detection of 1 nM glucose solution and a detection range from 1 nM to 50 μM in air at room temperature, which is lower than that of glucose sensors based on surface plasmon resonance spectroscopy, fluorescence signal transmission, and electrochemical signal transduction. The new glucose sensor provides a key technique for promising consuming application in biological system for detecting low levels of glucose on single cells or bacterial cultures.

  16. Emittance Measurements at the Langley Chemical Physics Laboratory

    Science.gov (United States)

    Lewis, B. W.

    1960-01-01

    Total hemispherical emittance measurements are made routinely for materials which may be heated by electrical resistance methods over the temperature range of 600 degrees to 2,000 F by using a black-body reference method. This employs a conical black body and a thermopile detector with a calcium fluoride lens. Emittance is obtained by measuring the radiant flux from the specimen strip and comparing it with the flux from an equal area of the black-body cone at the same temperature. The temperature measurements are made by use of thermocouples. It is planned to extend the temperature range of this type of measurement to temperatures above 2,000 F. Another technique has been investigated for measuring emittance of materials not amenable to electrical heating or thermocouple attachment. This method uses a black-body-cavity furnace similar to that used in reference 5 to measure emittance of transparent materials such as glass. The method employs a heated black-body cavity in which the semicircular specimen is allowed to come to the equilibrium temperature of the cavity and then is rotated in front of a water-cooled viewing port where a sensitive thermistor detector alternately views the specimen surface and the black-body cavity. The ratio of the two readings gives the specimen emittance directly, for the temperature of the black body. The detector output is recorded on a fast Brown self-balancing potentiometer. The furnace is provided with a water-cooled blackened shutter which may be inserted behind the specimen to eliminate any transmitted black-body radiation if the specimen is transparent. This apparatus is capable of measuring total normal emittance over the temperature range of 1,000 degrees to 2,000 F. Preliminary data for boron nitride specimens of two thicknesses are shown where total normal emittance is plotted against temperature for two experimental conditions: (1) black-body radiation incident on the back of the specimen and (2) no black-body radiation

  17. Observation of negative differential transconductance in tunneling emitter bipolar transistors

    Science.gov (United States)

    van Veenhuizen, Marc J.; Locatelli, Nicolas; Moodera, Jagadeesh; Chang, Joonyeon

    2009-08-01

    We report on measurement of negative differential transconductance (NDTC) of iron (Fe)/magnesium-oxide (MgO)/silicon tunneling emitter NPN bipolar transistors. Device simulations reveal that the NDTC is a consequence of an inversion layer at the tunneling-oxide/P-silicon interface for low base voltages. Electrons travel laterally through the inversion layer into the base and give rise to an increase in collector current. The NDTC results from the recombination of those electrons at the interface between emitter and base contact which is dependent on the base voltage. For larger base voltages, the inversion layer disappears marking the onset of normal bipolar transistor behavior.

  18. Ultra-low emittance X-band photocathode RF gun

    Institute of Scientific and Technical Information of China (English)

    TANG Chuan-Xiang; LIU Xiao-Han

    2009-01-01

    In this paper,we present the simulation results of a 1.6 cell X-band photocathode RF gun for ultra-low emittance electron beams.It will work at 9.3 GHz.The emittance,bunch length,electron energy and energy spread at the gun exit are optimized at bunch charge of 1pC using PARMELA.Electron bunches type coupler is adopted in this gun and an initial simulation by MAFIA is also given in this paper.

  19. Carbon Nanotube Electron Emitter for X-ray Imaging

    Directory of Open Access Journals (Sweden)

    Jung Su Kang

    2012-11-01

    Full Text Available The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube emitter, and the transmitted X-ray image was of high resolution.

  20. The Deepest Spectrum in the Universe? Line Emission from Lyman-alpha Clouds at z 3

    Science.gov (United States)

    Bunker, Andrew J.; Rauch, M.; Haehnelt, M.; Becker, G.; Marleau, F.; Graham, J.; Research, European; Inter-Galactic Medium, Training Network on the

    2007-12-01

    We present the results of an extremely deep long-slit optical spectroscopic search for low-luminosity Lyman-alpha emitters. Over several years we have accumulated 150-hours integration on a single field with 8-10m telescopes (VLT/FORS2, Gemini/GMOS and Keck/LRIS) at a spectral resolution of 300km/s. This is the deepest spectrum ever obtained - our 1 sigma sensitivity to line emission in a 1 arcsec2 aperture is 1019erg/cm2/s. We have significant detections of 30 emission line objects, which are most likely Lyman-alpha emitters at 2.7emitters are significantly spatially extended (with median size 4arcsec, 30kpc) and could plausibly be the host population of the high column density Lyman-alpha absorption clouds seen in QSO spectra (the Damped Lyman-alpha Systems and the Lyman-Limit Systems).

  1. Review of alpha_s determinations

    OpenAIRE

    Pich, Antonio

    2013-01-01

    The present knowledge on the strong coupling is briefly summarized. The most precise determinations of alpha_s, at different energies, are reviewed and compared at the Z mass scale, using the predicted QCD running. The impressive agreement achieved between experimental measurements and theoretical predictions constitutes a beautiful and very significant test of Asymptotic Freedom, establishing QCD as the fundamental theory of the strong interaction. The world average value of the strong coupl...

  2. Recent $\\alpha$ decay half-lives and analytic expression predictions including superheavy nuclei

    CERN Document Server

    Royer, G

    2008-01-01

    New recent experimental $\\alpha$ decay half-lives have been compared with the results obtained from previously proposed formulas depending only on the mass and charge numbers of the $\\alpha$ emitter and the Q$\\alpha$ value. For the heaviest nuclei they are also compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulas. The correct agreement allows us to make predictions for the $\\alpha$ decay half-lives of other still unknown superheavy nuclei from these analytic formulas using the extrapolated Q$\\alpha$ of G. Audi, A. H. Wapstra, and C. Thibault [Nucl. Phys. A729, 337 (2003)].

  3. Alpha-1-antitrypsin augmentation therapy in deficient individuals enrolled in the Alpha-1 Foundation DNA and Tissue Bank

    OpenAIRE

    Tonelli, Adriano

    2009-01-01

    Adriano R Tonelli1, Farshid Rouhani1, Ning Li2, Pam Schreck1, Mark L Brantly11Alpha-1 Research Program, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, 2Department of Epidemiology and Biostatistics, University of Florida, Gainesville, Florida, USAIntroduction: Intravenous augmentation therapy with purified intravenous alpha-1 antitrypsin replaces the deficient protein and is the only currently approved treatment for alpha-1 antitrypsin deficiency (AAT...

  4. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    Energy Technology Data Exchange (ETDEWEB)

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R. [Vanderbilt Univ., Nashville, TN (United States); Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States); Fleetwood, D.M. [Sandia National Labs., Albuquerque, NM (United States); Kosier, S.L. [VTC Inc., Bloomington, MN (United States)

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps.

  5. Tesla transformer based 500 kv pulser for low emittance test stand at Paul Scherrer Institute

    CERN Document Server

    Paraliev, M; Ivkovic, S

    2011-01-01

    For the Low Emittance Gun (LEG) project at Paul Scherrer Institute a stable and reliable high voltage pulsed generator was needed in order to study low emittance beams generation and transport. The system had to provide variable asymmetric voltage pulse up to -500 kV with amplitude stability better than 1.2 part per thousand (ppt). The pulse should be applied to the cathode of variable gap accelerating diode providing voltage gradients up to more than 100 MV/m. A broad bandwidth electrical connection to the cathode is necessary in order to deliver fast cathode gating signal. The design of the pulser is presented as well as the optimization and implementation of some critical components in the system. A detailed electrical model of the pulsed generator was created in order to optimize and study its electrical behavior. The measured waveforms are compared to the simulated ones and output amplitude stability is discussed. Different electrode materials and surface treatments were studied to ensure breakdown free ...

  6. Treatment planning for internal emitter therapy: Methods, applications and clinical implications

    Energy Technology Data Exchange (ETDEWEB)

    Sgouros, G. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    1999-01-01

    Treatment planning involves three basic steps: (1) a procedure must be devised that will provide the most relevant information, (2) the procedure must be applied and (3) the resulting information must be translated into a definition of the optimum implementation. There are varying degrees of treatment planning that may be implemented in internal emitter therapy. As in chemotherapy, the information from a Phase 1 study may be used to treat patients based upon body surface area. If treatment planning is included on a patient-specific basis, a pretherapy, trace-labeled, administration of the radiopharmaceutical is generally required. The data collected following the tracer dose may range from time-activity curves of blood and whole-body for use in blood, marrow or total body absorbed dose estimation to patient imaging for three-dimensional internal emitter dosimetry. The most ambitious approach requires a three-dimensional set of images representing radionuclide distribution (SPECT or PET) and a corresponding set of images representing anatomy (CT or MRI). The absorbed dose (or dose-rate) distribution may be obtained by convolution of a point kernel with the radioactivity distribution or by direct Monte Carlo calculation. A critical requirement for both techniques is the development of an overall structure that makes it possible, in a routine manner, to input the images, to identify the structures of interest and to display the results of the dose calculations in a clinically relevant manner. 52 refs., 4 figs., 1 tab.

  7. Analysis of Urine for Pure Beta Emitters: Methods and Application

    DEFF Research Database (Denmark)

    Hou, Xiaolin

    2011-01-01

    by combustion to separate tritiated water from organically-bound tritium. Inorganic C-14 from organically-bound C-14, the separated tritium and C-14 were measured using liquid scintillation counting. Iodine-129, a long-lived beta emitter, is normally released to the atmosphere during the operation of nuclear...

  8. Calculation Of Extraction Optics For Ion System With Plazma Emitter

    CERN Document Server

    Frolov, B A

    2004-01-01

    The 2-D code for simulating of ion optics system of positive ion extraction from a plasma source is described. Example calculation of 100 kV optics for the extraction ion IHEP gun is presented. The trajectories of particles and emittance plots are resulted. The aberrations influ-ence strongly on ion optics for considered geometry.

  9. Magnetized Plasma Experiments Using Thermionic- Thermoelectronic Plasma Emitter

    Science.gov (United States)

    Kawamori, Eiichirou; Cheng, C. Z.; Fujikawa, Nobuko; Lee, Jyun-Yi; Peng, Albert

    2008-11-01

    We are developing a magnetic mirror device, which is the first magnetized plasma device in Taiwan, to explore basic plasma sciences relevant to fusion, space and astrophysical plasmas. Our research subjects include electromagnetically induced transparency (EIT), Alfven wave physics, and plasma turbulence. A large diameter (> 200 mm) plasma emitter1, which utilizes thermionic- thermoelectronic emission from a mixture of LaB6 (Lanthanum-hexaboride) and beta-eucryptite (lithium type aluminosylicate) powders, is employed as a plasma source because of its production ability of fully ionized plasma and controllability of plasma emission rate. The plasma emitter has been installed recently and investigation of its characteristics will be started. The employment of beta-eucryptite in plasma emitter is the first experimental test because such investigation of beta-eucryptite has previously been used only for Li+-ion source2. Our plan for magnetized plasma experiments and results of the plasma emitter investigation will be presented. 1. K. Saeki, S. Iizuka, N. Sato, and Y. Hatta, Appl. Phys. Lett., 37, 1980, pp. 37-38. 2. M. Ueda, R. R. Silva, R. M. Oliveira, H. Iguchi, J. Fujita and K. Kadota, J. Phys. D: Appl. Phys. 30 1997, pp. 2711--2716.

  10. Application of positron emitters to studies on plants

    Energy Technology Data Exchange (ETDEWEB)

    Ishioka, N.S.; Matsuoka, H. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Sekine, T. [and others

    1998-10-01

    A newly developed positron emitting tracer imaging system enables us to study dynamically the physiological function of plants, although this system covers, at present, a limited area in a plant. Production of the positron emitters {sup 11}C, {sup 13}N, {sup 18}F and {sup 48}V for this application, using an AVF cyclotron, is described. (author)

  11. Auger Emitter Based Radiotherapy- A Possible New Treatment for Cancer

    DEFF Research Database (Denmark)

    Fredericia, Pil; Groesser, Torsten; Severin, Gregory;

    2014-01-01

    damage produced by Low-LET radiation used in current radiotherapy (2-3) Considerable efforts have been made in the past twenty years to develop Auger emitter-based radiotherapy However, previous studies lack precise measurement of RBE, which is the fundamental factor defining the relationship between...

  12. Achieving ultra-high temperatures with a resistive emitter array

    Science.gov (United States)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  13. Emittance control and RF bunch compression in the NSRRC photoinjector

    Science.gov (United States)

    Lau, W. K.; Hung, S. B.; Lee, A. P.; Chou, C. S.; Huang, N. Y.

    2011-05-01

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  14. Emittance control and RF bunch compression in the NSRRC photoinjector

    International Nuclear Information System (INIS)

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  15. Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

    DEFF Research Database (Denmark)

    Frimmer, Martin; Chen, Yuntian; Koenderink, A. Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment whi...

  16. Measurement of Transverse Emittance in the Fermilab Booster.

    Science.gov (United States)

    Graves, William Sproull

    A new beam profile monitor has been built and installed in the Fermilab Booster synchrotron. It nondestructively measures the beam's vertical density distribution on a fast turn-by-turn basis. This enables one to measure the beam's transverse emittance and to observe emittance growth as it occurs. For high intensities (>2 times 10^{12 } protons), the normalized 95% emittance was observed to grow from 6pi mm-mrad at injection to 16pi mm-mrad at extraction. The initial (beam losses are shown to be caused by the space charge tune shift onto integer and 1/2 integer resonance lines. The growth near injection accounts for approximately 40% of the observed emittance increase throughout the acceleration cycle. The remaining 60% is due to two factors: slow linear growth due to betatron-motion driven by noise in the rf system; and faster growth after the transition energy that is caused by coupling of the longitudinal beam motion into the transverse planes.

  17. Transverse beam emittance measurement using quadrupole variation at KIRAMS-430

    Science.gov (United States)

    An, Dong Hyun; Hahn, Garam; Park, Chawon

    2015-02-01

    In order to produce a 430 MeV/u carbon ion (12 C 6+) beam for medical therapy, the Korea Institute of Radiological & Medical Sciences (KIRAMS) has carried out the development of a superconducting isochronous cyclotron, the KIRAMS-430. At the extraction of the cyclotron, an Energy Selection System (ESS) is located to modulate the fixed beam energy and to drive the ion beam through High Energy Beam Transport (HEBT) into the treatment room. The beam emittance at the ion beamline is to be measured to provide information on designing a beam with high quality. The well-known quadrupole variation method was used to determine the feasibility of measuring the transverse beam emittance. The beam size measured at the beam profile monitor (BPM) is to be utilized and the transformation of beam by transfer matrix is to be applied being taken under various transport condition of varying quadrupole magnetic strength. Two different methods where beam optics are based on the linear matrix formalism and particle tracking with a 3-D magnetic field distribution obtained by using OPERA3D TOSCA, are applied to transport the beam. The fittings for the transformation parameters are used to estimate the transverse emittance and the twiss parameters at the entrance of the quadrupole in the ESS. Including several systematic studies, we conclude that within the uncertainty the estimated emittances are consistent with the ones calculated by using Monte Carlo simulations.

  18. Selective-emitter crystalline silicon solar cells using phosphorus paste

    International Nuclear Information System (INIS)

    Selective-emitter structures have been studied to improve the conversion efficiency of crystalline silicon solar cells. However, such structures require additional complicated processes and incur extra cost. In this work, we used phosphorus paste (P-paste) to form a heavily-doped region beneath the grid and POCl3 to create a shallow emitter area. This method should be convenient to use in the solar-cell industry because it requires only additional P paste printing, compared to the case of homogeneous solar cells. Diffusion parameters including the temperature, diffusion time, and ambient gases were optimized. We observed that the spreading of the P paste was affected by the pyramidal size of the textured wafer due to the low viscosity of the P paste. The pyramidal height of the textured silicon surface was optimized at 3 μm to counterbalance the surface reflectance and the spreading of the P paste. The short-circuit current density of the completed selective emitter solar cell was increased, and an improvement of blue response in the internal quantum efficiency was seen while contact properties such as the fill factor deteriorated due to the spreading of the P paste and the thin emitter on top of the pyramid of the textured silicon surface. Double printing of the P paste was applied to solve this contact problem; a fill factor improvement of 2.4% was obtained.

  19. Selective-emitter crystalline silicon solar cells using phosphorus paste

    Science.gov (United States)

    Jeong, Kyung Taek; Kang, Min Gu; Song, Hee-eun

    2014-11-01

    Selective-emitter structures have been studied to improve the conversion efficiency of crystalline silicon solar cells. However, such structures require additional complicated processes and incur extra cost. In this work, we used phosphorus paste (P-paste) to form a heavily-doped region beneath the grid and POCl3 to create a shallow emitter area. This method should be convenient to use in the solar-cell industry because it requires only additional P paste printing, compared to the case of homogeneous solar cells. Diffusion parameters including the temperature, diffusion time, and ambient gases were optimized. We observed that the spreading of the P paste was affected by the pyramidal size of the textured wafer due to the low viscosity of the P paste. The pyramidal height of the textured silicon surface was optimized at 3 μm to counterbalance the surface reflectance and the spreading of the P paste. The short-circuit current density of the completed selective emitter solar cell was increased, and an improvement of blue response in the internal quantum efficiency was seen while contact properties such as the fill factor deteriorated due to the spreading of the P paste and the thin emitter on top of the pyramid of the textured silicon surface. Double printing of the P paste was applied to solve this contact problem; a fill factor improvement of 2.4% was obtained.

  20. Development of High Intensity Beam Emittance Measurement Unit

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Three sets of High Intensity Beam Emittance Measurement Units (HIBEMUs) are being developed at Peking University. They are HIBEMU-2 (slit-wire type, one direction), HIBEMU-3 (Allison scanner type, one direction) and HIBEMU-4 (slit-wire type, two directions). For HIBEMU-2 and HIBEMU-3, more recent work has been done on software redesign in order to measure beam emittance and to draw phase diagram more efficiently and precisely. Software for control and data processing of them were developed in Labveiw environment, trying to improve calculation rationality and to offer user-friendly interface. Mechanical modification was also done for HIBEMU-3, mainly concentrating on the protection of Faraday cups from being overheated by the high intensity beam and also from interference of secondary electrons. This paper will also cover the mechanical structure as well as the software development of HIBEMU-4, which is a two-direction emittance scanner newly designed and manufactured for the high energy beam transport (HEBT) of Peking University Neutron Imaging FaciliTY (PKUNIFTY). At the end of this paper, comparison and analysis of the three HIBEMUs are given to draw forth better design of the future emittance measurement facility.

  1. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  2. Emitter/absorber interface of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tao [Physics Department, Colorado State University, Fort Collins, Colorado 80523, USA; Kanevce, Ana [National Renewable Energy Laboratory, Golden, Colorado 80401, USA; Sites, James R. [Physics Department, Colorado State University, Fort Collins, Colorado 80523, USA

    2016-06-17

    The performance of CdTe solar cells can be very sensitive to their emitter/absorber interfaces, especially for high-efficiency cells with improved bulk properties. When interface defect states are located at efficient recombination energies, performance losses from acceptor-type interface defects can be significant. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e. defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV /= 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a 'cliff' (.delta..EC < 0 eV) is likely to allow many holes in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. In addition, a thin and highly-doped emitter can invert the absorber, form a large hole barrier, and decrease device performance losses due to high interface defect density. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. Other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ..delta..EC. These materials are predicted

  3. New ALPHA-2 magnet

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    On 21 June, members of the ALPHA collaboration celebrated the handover of the first solenoid designed for the ALPHA-2 experiment. The magnet has since been successfully installed and is working well.   Khalid Mansoor, Sumera Yamin and Jeffrey Hangst in front of the new ALPHA-2 solenoid. “This was the first of three identical solenoids that will be installed between now and September, as the rest of the ALPHA-2 device is installed and commissioned,” explains ALPHA spokesperson Jeffrey Hangst. “These magnets are designed to allow us to transfer particles - antiprotons, electrons and positrons - between various parts of the new ALPHA-2 device by controlling the transverse size of the particle bunch that is being transferred.” Sumera Yamin and Khalid Mansoor, two Pakistani scientists from the National Centre for Physics in Islamabad, came to CERN in February specifically to design and manufacture these magnets. “We had the chance to work on act...

  4. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures

    CERN Document Server

    Filter, Robert; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-01-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

  5. Effect of plasmonic near field on the emittance of plasmon-enhanced photocathode

    CERN Document Server

    Jiang, Zeng-gong; Li, Xu-dong; Zhang, Meng; Gu, Duan

    2016-01-01

    The introduction of the surface plasmon polarizations makes the emittance of the photocathode complicated. In this paper, the emittance of plasmon-enhanced photocathode is analyzed. It is first demonstrated that the plasmonic near field can increase the emittance of the plasmon-enhanced photocathode. A simulation method has been used to estimate the emittance caused by plasmonic near field, and the suppression method also has been discussed, both of which are significant for the design of high performance plasmon-enhanced photocathode.

  6. Cooperative behavior of quantum dipole emitters coupled to a zero-index nanoscale waveguide

    OpenAIRE

    Sokhoyan, Ruzan; Harry A. Atwater

    2015-01-01

    We study cooperative behavior of quantum dipole emitters coupled to a rectangular waveguide with dielectric core and silver cladding. We investigate cooperative emission and inter-emitter entanglement generation phenomena for emitters whose resonant frequencies are near the frequency cutoff of the waveguide, where the waveguide effectively behaves as zero-index metamaterial. We show that coupling emitters to a zero-index waveguide allows one to relax the constraint on precision positioning of...

  7. Fission- and alpha-track study of biogeochemistry of plutonium and uranium in carbonates of Bikini and Enewetak atolls. Summary report, 1 July 1974--31 August 1977

    International Nuclear Information System (INIS)

    Alpha emitters of pCi/g amounts have been detected with a resolution of a few micrometers using a solid state track detector (cellulose nitrate) to map the activity in a coral sample from Bikini. Calibration methods used include: a Pu source of 0.15 μCi in conjunction with polycarbonate and CaCO3 absorbers of different thicknesses (2 to 30 micrometers), and a powdered coral sample which had been analyzed previously for alpha emitters by chemical methods in conjunction with an alpha spectrometer. 0.04 mm3 can be measured routinely; lower concentrations can be determined but with less resolution. The alpha emitter concentration in CaCO3 of the coral Favites virens from Bikini lagoon was analyzed by placing the detector directly on the slab sample for thirty days. Analyses of sections and thin sections of this coral slab cut perpendicular to one another, but parallel to the direction of coral growth, give very different concentrations and distributions of alpha emitters

  8. Emitter/absorber interface of CdTe solar cells

    Science.gov (United States)

    Song, Tao; Kanevce, Ana; Sites, James R.

    2016-06-01

    The performance of CdTe solar cells can be very sensitive to the emitter/absorber interface, especially for high-efficiency cells with high bulk lifetime. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e., defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV ≤ ΔEC ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se2 (CIGS) cells. The basic principle is that positive ΔEC, often referred to as a "spike," creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (ΔEC ≥ 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a "cliff" (ΔEC CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. The ΔEC of other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ΔEC. These materials are predicted to yield higher voltages and would therefore be better candidates for the CdTe-cell emitter.

  9. Alpha Shapes and Proteins

    DEFF Research Database (Denmark)

    Winter, Pawel; Sterner, Henrik; Sterner, Peter

    2009-01-01

    We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....

  10. Using antennas separated in flight direction to avoid effect of emitter clock drift in geolocation

    Science.gov (United States)

    Ormesher, Richard C.; Bickel, Douglas L

    2012-10-23

    The location of a land-based radio frequency (RF) emitter is determined from an airborne platform. RF signaling is received from the RF emitter via first and second antennas. In response to the received RF signaling, signal samples for both antennas are produced and processed to determine the location of the RF emitter.

  11. Spacecraft charging control by thermal, field emission with lanthanum-hexaboride emitters

    Science.gov (United States)

    Morris, J. F.

    1978-01-01

    Thermal, field emitters of lanthanum (or perhaps cerium) hexaboride (LaB6) with temperature variability up to about 1500K are suggested for spacecraft charging control. Such emitters operate at much lower voltages with considerably more control and add plasma-diagnostic versatility. These gains should outweigh the additional complexity of providing heat for the LaB6 thermal, field emitter.

  12. Calculated and measured emittance of sputter-type negative-ion source

    International Nuclear Information System (INIS)

    A method for calculating the beam current and emittance of a negative ion beam from a sputter-type source is described. Calculations are compared to measured emittance. The dependence of the emittance on ion source parameters such as cathode shape, exit aperture diameter, and cathode voltage is discussed

  13. Thick target yield measurement of {sup 211}At through the nuclear reaction {sup 209}Bi({alpha}, 2n)

    Energy Technology Data Exchange (ETDEWEB)

    Alfarano, A [Institute for Health and Consumer Protection, IHCP, Joint Research Centre, via E. Fermi 1, 21020 Ispra, Varese (Italy); Abbas, K [Institute for Health and Consumer Protection, IHCP, Joint Research Centre, via E. Fermi 1, 21020 Ispra, Varese (Italy); Holzwarth, U [Institute for Health and Consumer Protection, IHCP, Joint Research Centre, via E. Fermi 1, 21020 Ispra, Varese (Italy); Bonardi, M [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, 20090 Segrate, Milan (Italy); Groppi, F [Universita degli Studi di Milano and INFN-Milano, LASA, Radiochemistry Laboratory, via F.lli Cervi 201, 20090 Segrate, Milan (Italy); Alfassi, Z [Department of Nuclear Engineering, Ben Gurion University, 84105 Beer Sheva (Israel); Menapace, E [ENEA, Applied Physics Division, Bologna (Italy); Gibson, P N [Institute for Health and Consumer Protection, IHCP, Joint Research Centre, via E. Fermi 1, 21020 Ispra, Varese (Italy)

    2006-05-15

    Radionuclide Therapy (RNT) and Radioimmunotherapy (RIT) are potentially of great interest for cancer therapy. In many therapeutic applications alpha emitters should be much more effective than already-approved beta emitters due to the short range and high linear energy transfer of alpha particles. {sup 213}Bi is an important alpha emitter already used in clinical trials but the half-life of this radioisotope is short (46 minutes) and so its use is limited for certain therapies. {sup 211}At is potentially very interesting for medical purposes because of its longer half-life of 7.2 hours, and suitable decay scheme. We have studied the cyclotron-based production of {sup 211}At via the reaction {sup 209}Bi({alpha}, 2n), this production route probably being the most promising in the long term. The energy dependence of thick target yields and the reaction cross sections for the production of {sup 211}At and {sup 210}At were determined and found to be in good agreement with literature. The best energy to produce {sup 211}At is 28-29 MeV. The possible production of the undesired, highly radiotoxic, and long-lived alpha-emitting {sup 210}Po (138.38 days), which is produced from decay of {sup 210}At, is also discussed.

  14. Performance comparison of scintillators for alpha particle detectors

    Science.gov (United States)

    Morishita, Yuki; Yamamoto, Seiichi; Izaki, Kenji; Kaneko, Junichi H.; Toui, Kohei; Tsubota, Youichi; Higuchi, Mikio

    2014-11-01

    Scintillation detectors for alpha particles are often used in nuclear fuel facilities. Alpha particle detectors have also become important in the research field of radionuclide therapy using alpha emitters. ZnS(Ag) is the most often used scintillator for alpha particle detectors because its light output is high. However, the energy resolution of ZnS(Ag)-based scintillation detectors is poor because they are not transparent. A new ceramic sample, namely the cerium doped Gd2Si2O7 (GPS) scintillator, has been tested as alpha particle detector and its performances have been compared to that one of three different scintillating materials: ZnS(Ag), GAGG and a standard plastic scintillator. The different scintillating materials have been coupled to two different photodetectors, namely a photomultiplier tube (PMT) and a Silicon Photo-multiplier (Si-PM): the performances of each detection system have been compared. Promising results as far as the energy resolution performances (10% with PMT and 14% with Si-PM) have been obtained in the case of GPS and GAGG samples. Considering the quantum efficiencies of the photodetectors under test and their relation to the emission wavelength of the different scintillators, the best results were achieved coupling the GPS with the PMT and the GAGG with the Si-PM

  15. Targeted Alpha Therapy: From Alpha to Omega

    International Nuclear Information System (INIS)

    This review covers the broad spectrum of Targeted Alpha Therapy (TAT) research in Australia; from in vitro and in vivo studies to clinical trials. The principle of tumour anti-vascular alpha therapy (TAVAT) is discussed in terms of its validation by Monte Carlo calculations of vascular models and the potential role of biological dosimetry is examined. Summmary of this review is as follows: 1. The essence of TAT 2. Therapeutic objectives 3. TAVAT and Monte Carlo microdosimetry 4. Biological dosimetry 5. Preclinical studies 6. Clinical trials 7. What next? 8. Obstacles. (author)

  16. Predicting the Redshift 2 H-Alpha Luminosity Function Using [OIII] Emission Line Galaxies

    Science.gov (United States)

    Mehta, Vihang; Scarlata, Claudia; Colbert, James W.; Dai, Y. S.; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry I.; Bagley, Micaela; Beck, Melanie; Ross, Nathaniel R.; Rutkowski, Michael; Wang, Yun

    2015-01-01

    Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure Baryonic Acoustic Oscillations (BAOs) in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the WFC3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of H-alpha emitters observable by these future surveys. WISP is an ongoing Hubble Space Telescope slitless spectroscopic survey, covering the 0.8 - 1.65 micrometers wavelength range and allowing the detection of H-alpha emitters up to z approximately equal to 1.5 and [OIII] emitters to z approximately equal to 2.3. We derive the H-alpha-[OIII] bivariate line luminosity function for WISP galaxies at z approximately equal to 1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurement, and demonstrate how it can be used to derive the H-alpha luminosity function from exclusively fitting [OIII] data. Using the z approximately equal to 2 [OIII] line luminosity function, and assuming that the relation between H-alpha and [OIII] luminosity does not change significantly over the redshift range, we predict the H-alpha number counts at z approximately equal to 2 - the upper end of the redshift range of interest for the future surveys. For the redshift range 0.7 less than z less than 2, we expect approximately 3000 galaxies per sq deg for a flux limit of 3 x 10(exp -16) ergs per sec per sq cm (the proposed depth of Euclid galaxy redshift survey) and approximately 20,000 galaxies per sq deg for a flux limit of approximately 10(exp -16) ergs per sec per sq cm (the baseline depth of WFIRST galaxy redshift survey).

  17. A improved method for the analysis of alpha spectra

    International Nuclear Information System (INIS)

    In this work we describe a methodology, developed in the last years, for the analysis of alpha emitters spectra, obtained with implanted ion detectors, that tend to solve some of the problems that shows this type of spectra. This is an improved methodology respect to that described in a previous publication. The method is based on the application of a mathematical function that allows to model the tail of an alpha peak, to evaluate the part of the peak that is not seen in the cases of partial superposition with another peak. Also, a calculation program that works in a semiautomatic way, with the possibility of interactive intervention of the analyst, has been developed simultaneously and is described in detail. (author)

  18. Alpha radioactivity for proton-rich even Pb isotopes

    Indian Academy of Sciences (India)

    Arati Devi; S Prakash; I Mehrotra

    2009-04-01

    Half-lives for alpha radioactivity from proton-rich even Pb isotopes in the range = 182–202 have been calculated using the unified fission-like approach. The geometrical shape of the potential barrier is parametrized in terms of a highly versatile, asymmetric and analytically solvable form of potential based on Ginnochio’s potential. Good agreement with the experimental data has been obtained with the variation of just one parameter. Half-lives of three unknown alpha emitters in the neutron-deficient Pb chain (198Pb, 200Pb and 204Pb) have been predicted. The exact expression for the transmission coefficient has been compared with those obtained from WKB approximation method for symmetric Eckart potential.

  19. Buffett’s Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting...

  20. Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth

    CERN Document Server

    Jaskot, A E

    2014-01-01

    We suggest that low optical depth in the Lyman continuum (LyC) may relate the Ly-alpha emission, C II and Si II absorption, and C II* and Si II* emission seen in high-redshift galaxies. We base this analysis on Hubble Space Telescope COS spectra of four Green Pea (GP) galaxies, which may be analogs of z>2 Ly-alpha emitters (LAEs). In the two GPs with the strongest Ly-alpha emission, the Ly-alpha line profiles do not show the typical effects of resonant scattering. Instead, the Ly-alpha profiles resemble the H-alpha line profiles of evolved star ejecta, suggesting that the Ly-alpha emission originates from a low column density and similar outflow geometry. The weak C II absorption and presence of non-resonant C II* emission in these GPs support this interpretation and imply a low LyC optical depth along the line of sight. In two additional GPs, weak Ly-alpha emission and strong C II absorption suggest a higher optical depth. These two GPs differ in their Ly-alpha profile shapes and C II* emission strengths, ho...

  1. Emittance Measurements from a Laser Driven Electron Injector

    International Nuclear Information System (INIS)

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 (angstrom), the LCLS requires an electron injector that can produce an electron beam with approximately 1 π mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be ∼ 13 π mm-mrad for 5 ps and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.5 π mm-mrad

  2. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    Energy Technology Data Exchange (ETDEWEB)

    Davydenko, V. I., E-mail: V.I.Davydenko@inp.nsk.su; Ivanov, A. A., E-mail: A.A.Ivanov@inp.nsk.su; Shul’zhenko, G. I. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  3. Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, Jayakar C.T.; Thurman-Keup, R.; Johnson, A.; Lumpkin, A.H.; Edwards, H.; Ruan, J.; Santucci, J.; Sun, Y.E.-; Church, M.; /Fermilab; Piot, P.; /Fermilab /Northern Illinois U.

    2010-08-01

    Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchanger to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at A0 photoinjector.

  4. Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector

    CERN Document Server

    Thangaraj, Jayakar C T; Johnson, A; Lumpkin, A H; Edwards, H; Ruan, J; Santucci, J; Sun, Y E -; Church, M; Piot, P

    2012-01-01

    Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at the A0 photoinjector.

  5. Alpha-particle diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Young, K.M.

    1991-01-01

    This paper will focus on the state of development of diagnostics which are expected to provide the information needed for {alpha}- physics studies in the future. Conventional measurement of detailed temporal and spatial profiles of background plasma properties in DT will be essential for such aspects as determining heating effectiveness, shaping of the plasma profiles and effects of MHD, but will not be addressed here. This paper will address (1) the measurement of the neutron source, and hence {alpha}-particle birth profile, (2) measurement of the escaping {alpha}-particles and (3) measurement of the confined {alpha}-particles over their full energy range. There will also be a brief discussion of (4) the concerns about instabilities being generated by {alpha}-particles and the methods necessary for measuring these effects. 51 refs., 10 figs.

  6. Imaging alpha particle detector

    Science.gov (United States)

    Anderson, D.F.

    1980-10-29

    A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  7. Structural determinants within residues 180-199 of the rodent. alpha. 5 nicotinic acetylcholine receptor subunit involved in. alpha. -bungarotoxin binding

    Energy Technology Data Exchange (ETDEWEB)

    McLane, K.E.; Xiadong Wu; Conti-Tronconi, B.M. (Univ. of Minnesota, St. Paul (United States))

    1991-11-05

    Synthetic peptides corresponding to sequence segments of the nicotinic acetylcholine receptor (nAChR) {alpha} subunits have been used to identify regions that contribute to formation of the binding sites for cholinergic ligands. The authors have previously defined {alpha}-bungarotoxin ({alpha}-BTX) binding sequences between residues 180 and 199 of a putative rat neuronal nAChR {alpha} subunit, designated {alpha}5, and between residues 181 and 200 of the chick neuronal {alpha}7 and {alpha}8 subunits. These sequences are relatively divergent compared with the Torpedo and muscle nAChR {alpha}1 {alpha}-BTX binding sites, which indicates a serious limitation of predicting functional domains of proteins based on homology in general. Given the highly divergent nature of the {alpha}5 sequence, they were interested in determining the critical amino acid residues for {alpha}-BTX binding. In the present study, the effects of single amino acid substitutions of Gly or Ala for each residue of the rat {alpha}(180-199) sequence were tested, using a competition assay, in which peptides compete for {sup 125}I-{alpha}-BTX binding with native Torpedo nAChR. These results indicate that a disulfide bridge between the vicinal cysteines at positions 191 and 192 of the {alpha}5 sequence is not an absolute requirement for {alpha}-BTX binding activity.

  8. Preparation and preclinical evaluation of {sup 211}At-labelled compounds for {alpha}-particle radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, R.H.

    1994-12-31

    The interest for {alpha}-particle emitters in internal radiotherapy is increasing due to improved conjugation chemistry. Experimental work has concentrated on {sup 211}At and {sup 212}Bi since these to nuclides have radiochemical and physical properties suitable for medical application. In this report it is demonstrated that biologically active {sup 211}At-labelled compounds can be prepared within a relatively short time allowing utilization of this 7.2 h {alpha}-particle. It is further shown that {sup 211}At-TP-3 treatment of human osteosarcoma in vitro gives promising therapeutic ratios. 76 refs., 5 figs., 3 tabs.

  9. Long-term aqueous alteration kinetics of an alpha-doped SON68 borosilicate glass

    OpenAIRE

    TRIBET M.; ROLLAND Séverine; S. Peuget; Magnin, Magali; BROUDIC Véronique; JANSSEN ARNE; Wiss, Thierry; JEGOU C.; Toulhoat, Pierre

    2013-01-01

    The long-term behavior of nuclear glass subjected to alpha radiation by minor actinides must be investigated with a view to geological disposal. This study focuses on the effect of alpha radiation on the chemical reactivity of R7T7 glass with pure water, mainly on the residual alteration rate regime. A glass specimen doped with 0.85 wt% 239PuO2 (α emitter) is leached under static conditions in argon atmosphere at 90°C and at a high surface-area-to-volume ratio (S/V = 20 cm-1). The alteration ...

  10. Evolution of the spherical cavity radius generated around a subsurface drip emitter

    Directory of Open Access Journals (Sweden)

    M. Gil

    2010-06-01

    Full Text Available The emitter discharge in subsurface drip irrigation can be affected by soil properties. A positive pressure develops at the emitter outlet where a spherical cavity is assumed to form. In steady-state conditions, the pressure in the soil relates to soil hydraulic properties, the emitter discharge, and the cavity radius. This pressure in the soil is very sensitive to the cavity radius. In this paper, the development of the cavity around the emitter outlet was measured for various emitter discharges in laboratory tests carried out in containers with uniform loamy soils. A trend between soil pressure and emitter discharge was established that illustrates the performance of buried emitters in the field. Its application to the prediction of water distribution in subsurface drip irrigation units and its effect on the estimation of irrigation performance are also shown.

  11. Electrically pumped single-defect light emitters in WSe$_2$

    CERN Document Server

    Schwarz, S; Withers, F; Maguire, J K; Foster, A P; Dufferwiel, S; Hague, L; Makhonin, M N; Wilson, L R; Geim, A K; Novoselov, K S; Tartakovskii, A I

    2016-01-01

    Recent developments in fabrication of van der Waals heterostructures enable new type of devices assembled by stacking atomically thin layers of two-dimensional materials. Using this approach, we fabricate light-emitting devices based on a monolayer WSe$_2$, and also comprising boron nitride tunnelling barriers and graphene electrodes, and observe sharp luminescence spectra from individual defects in WSe$_2$ under both optical and electrical excitation. This paves the way towards the realization of electrically-pumped quantum emitters in atomically thin semiconductors. In addition we demonstrate tuning by more than 1 meV of the emission energy of the defect luminescence by applying a vertical electric field. This provides an estimate of the permanent electric dipole created by the corresponding electron-hole pair. The light-emitting devices investigated in our work can be assembled on a variety of substrates enabling a route to integration of electrically pumped single quantum emitters with existing technologi...

  12. Electron Cloud at Low Emittance in CesrTA

    International Nuclear Information System (INIS)

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  13. Quantum Emitters near Layered Plasmonic Nanostructures: Decay Rate Contributions

    CERN Document Server

    Pors, Anders

    2016-01-01

    We introduce a numerical framework for calculating decay rate contributions when excited two-level quantum emitters are located near layered plasmonic nanostructures, particularly emphasizing the case of plasmonic nanostructures atop metal substrates where three decay channels exist: free space radiation, Ohmic losses, and excitation of surface plasmon polaritons (SPPs). The calculation of decay rate contributions is based on Huygen's equivalence principle together with a near-field to far-field transformation of the local electric field, thereby allowing us to discern the part of the electromagnetic field associated with free propagating waves rather than SPPs. The methodology is applied to the case of an emitter inside and near a gap-plasmon resonator, emphasizing strong position and orientation dependencies of the total decay rate, contributions of different decay channels, radiation patterns, and directivity of SPP excitation.

  14. Emittance preservation during bunch compression with a magnetized beam

    Energy Technology Data Exchange (ETDEWEB)

    Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-02

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based on combining a finite solenoid field where the beam is generated together with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  15. Crystalline silicon solar cells with high resistivity emitter

    Science.gov (United States)

    Panek, P.; Drabczyk, K.; Zięba, P.

    2009-06-01

    The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl3 resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.

  16. Coupling of individual quantum emitters to channel plasmons

    CERN Document Server

    Bermúdez-Ureña, Esteban; Geiselmann, Michael; Marty, Renaud; Radko, Ilya P; Holmgaard, Tobias; Alaverdyan, Yury; Moreno, Esteban; García-Vidal, Francisco J; Bozhevolnyi, Sergey I; Quidant, Romain

    2015-01-01

    Efficient light-matter interaction lies at the heart of many emerging technologies that seek on-chip integration of solid-state photonic systems. Plasmonic waveguides, which guide the radiation in the form of strongly confined surface plasmon-polariton modes, represent a promising solution to manipulate single photons in coplanar architectures with unprecedented small footprints. Here we demonstrate coupling of the emission from a single quantum emitter to the channel plasmon polaritons supported by a V-groove plasmonic waveguide. Extensive theoretical simulations enable us to determine the position and orientation of the quantum emitter for optimum coupling. Concomitantly with these predictions, we demonstrate experimentally that 42% of a single nitrogen vacancy centre emission efficiently couples into the supported modes of the V-groove. This work paves the way towards practical realization of efficient and long distance transfer of energy for integrated solid-state quantum systems.

  17. A New SIMOX Emitter Switching Thyristor--BO-ECT

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bo; Alex Q.Huang

    2001-01-01

    SIMOX Emitter switching thyristor(SIMEST) is a new MOS-gated thyristor with highvoltage current saturation capability. In this paper,an improved SIMEST, the Buried-Oxide Emitter Controlled Thyristor (BO-ECT) is proposed. Comparing with the SIMEST, the BO-ECT not only has a simple gate and source metalization structure and is therefore easy for layout design, but it also has an improved high-voltage current saturation capability. The operational mechanism and the forward biased safe operating area (FBSOA) are analyzed. Two-dimensional simulation results indicate that the BO-ECT has a much lower forward voltage drop than that of the IGBT while at the same time has a wider or similar FBSOA as the IGBT.

  18. Extended emitter target tracking using GM-PHD filter.

    Directory of Open Access Journals (Sweden)

    Youqing Zhu

    Full Text Available If equipped with several radar emitters, a target will produce more than one measurement per time step and is denoted as an extended target. However, due to the requirement of all possible measurement set partitions, the exact probability hypothesis density filter for extended target tracking is computationally intractable. To reduce the computational burden, a fast partitioning algorithm based on hierarchy clustering is proposed in this paper. It combines the two most similar cells to obtain new partitions step by step. The pseudo-likelihoods in the Gaussian-mixture probability hypothesis density filter can then be computed iteratively. Furthermore, considering the additional measurement information from the emitter target, the signal feature is also used in partitioning the measurement set to improve the tracking performance. The simulation results show that the proposed method can perform better with lower computational complexity in scenarios with different clutter densities.

  19. Field emission from nanotube bundle emitters at low fields

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Q.H.; Corrigan, T.D.; Dai, J.Y.; Chang, R.P. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Krauss, A.R. [Materials Science and Chemistry Divisions, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    1997-06-01

    The fabrication of nanotube field emitters with an onset field as low as 0.8 V/{mu}m is described and the low-field electron emission mechanism is discussed. These emitters are made using nanotube cathode deposit with the addition of epoxy resin. The preferred orientation of nanotubes in nanotube bundles of the deposit is preserved. The nanotube tips are sharpened by exposing the nanotube bundle surface to a microwave oxygen plasma. The local-field enhancement factor is estimated to be 8000 by using the Fowler{endash}Nordheim equation. The low onset field is attributed to the well-distributed, highly orientated sharp tips at the sample surface. {copyright} {ital 1997 American Institute of Physics.}

  20. Electron Cloud at Low Emittance in CesrTA

    CERN Document Server

    Palmer, Mark; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; Livezey, Jesse; Lyndaker, Aaron; Makita, Junki; McDonald, Michael; Medjidzade, Valeri; Meller, Robert; O'Connell, Tim; Peck, Stuart; Peterson, Daniel; Ramirez, Gabriel; Rendina, Matthew; Revesz, Peter; Rider, Nate; Rice, David; Rubin, David; Sagan, David; Savino, James; Schwartz, Robert; Seeley, Robert; Sexton, James; Shanks, James; Sikora, John; Smith, Eric; Strohman, Charles; Williams, Heather; Antoniou, Fanouria; Calatroni, Sergio; Gasior, Marek; Jones, Owain Rhodri; Papaphilippou, Yannis; Pfingstner, Juergen; Rumolo, Giovanni; Schmickler, Hermann; Taborelli, Mauro; Asner, David; Boon, Laura; Garfinkel, Arthur; Byrd, John; Celata, Christine; Corlett, John; De Santis, Stefano; Furman, Miguel; Jackson, Alan; Kraft, Rick; Munson, Dawn; Penn, Gregory; Plate, David; Venturini, Marco; Carlson, Benjamin; Demma, Theo; Dowd, Rohan; Flanagan, John; Jain, Puneet; Kanazawa, Ken-ichi; Kubo, Kiyoshi; Ohmi, Kazuhito; Sakai, Hiroshi; Shibata, Kyo; Suetsugu, Yusuke; Tobiyama, Makoto; Gonnella, Daniel; Guo, Weiming; Harkay, Katherine; Holtzapple, Robert; Jones, James; Wolski, Andrzej; Kharakh, David; Ng, Johnny; Pivi, Mauro; Wang, Lanfa; Ross, Marc; Tan, Cheng-Yang; Zwaska, Robert; Schachter, Levi; Wilkinson, Eric

    2010-01-01

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud’s effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results

  1. First observation of the exchange of transverse and longitudinal emittances

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, J.; Johnson, A.S.; Lumpkin, A.H.; Thurman-Keup, R.; Edwards, H.; Fliller, R.P.; Koeth, T.; Sun, Y.-E; /Fermilab

    2011-02-01

    An experimental program to demonstrate a novel phase space manipulation in which the horizontal and longitudinal emittances of a particle beam are exchanged has been completed at the Fermilab A0 Photoinjector. A new beamline, consisting of a TM{sub 110} deflecting mode cavity flanked by two horizontally dispersive doglegs has been installed. We report on the first direct observation of transverse and longitudinal emittance exchange: {l_brace}{var_epsilon}{sub x}{sup n}, {var_epsilon}{sub y}{sup n}, {var_epsilon}{sub z}{sup n}{r_brace} = {l_brace} 2.9 {+-} 0.1, 2.4 {+-} 0.1, 13.1 {+-} 1.3{r_brace} {yields} {l_brace}11.3 {+-} 1.1, 2.9 {+-} 0.5, 3.1 {+-} 0.3{r_brace} mm-mrad.

  2. Matching of horizontal and vertical emittances using a thin scatterer

    International Nuclear Information System (INIS)

    An isocentric superconducting rotating-gantry for heavy-ion therapy is being developed at NIRS. This rotating gantry can transport heavy ions having 430 MeV/u to an isocenter with irradiation angles of over ±180 degrees, and is further capable of performing fast raster-scanning irradiation. In the treatment using the rotating gantry, it is important to obtain a circular beam spot at the isocenter independent of the gantry angle. To accomplish this, we initially determined phase-space distributions of extracted beams from the HIMAC synchrotron ring, and further, matching of horizontal and vertical emittances using a thin scatterer was performed. We report results of the phase-space measurements as well as the emittance matching. (author)

  3. Electron Cloud at Low Emittance in CesrTA

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Mark; /Cornell U., CLASSE; Alexander, James; /Cornell U., CLASSE; Billing, Michael; /Cornell U., CLASSE; Calvey, Joseph; /Cornell U., CLASSE; Conolly, Christopher; /Cornell U., CLASSE; Crittenden, James; /Cornell U., CLASSE; Dobbins, John; /Cornell U., CLASSE; Dugan, Gerald; /Cornell U., CLASSE; Eggert, Nicholas; /Cornell U., CLASSE; Fontes, Ernest; /Cornell U., CLASSE; Forster, Michael; /Cornell U., CLASSE; Gallagher, Richard; /Cornell U., CLASSE; Gray, Steven; /Cornell U., CLASSE; Greenwald, Shlomo; /Cornell U., CLASSE; Hartill, Donald; /Cornell U., CLASSE; Hopkins, Walter; /Cornell U., CLASSE; Kreinick, David; /Cornell U., CLASSE; Kreis, Benjamin; /Cornell U., CLASSE; Leong, Zhidong; /Cornell U., CLASSE; Li, Yulin; /Cornell U., CLASSE; Liu, Xianghong; /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /Cornell U., CLASSE /CERN /CERN /CERN /CERN /CERN /CERN; /more authors..

    2012-07-06

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  4. Developments of fast emittance monitors for ion sources at RCNP

    Energy Technology Data Exchange (ETDEWEB)

    Yorita, T., E-mail: yorita@rcnp.osaka-u.ac.jp; Hatanaka, K.; Fukuda, M.; Shimada, K.; Yasuda, Y.; Saito, T.; Tamura, H.; Kamakura, K. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 567-0047 (Japan)

    2016-02-15

    Recently, several developments of low energy beam transport line and its beam diagnostic systems have been performed to improve the injection efficiency of ion beam to azimuthally varying field cyclotron at Research Center for Nuclear Physics, Osaka University. One of those is the fast emittance monitor which can measure within several seconds for the efficient beam development and a Pepper-Pot Emittance Monitor (PPEM) has been developed. The PPEM consists of pepper-pot mask, multichannel plate, fluorescent screen, mirror, and CCD camera. The CCD image is taken via IEEE1394b to a personal computer and analyzed immediately and frequently, and then real time measurement with about 2 Hz has been achieved.

  5. Developments of fast emittance monitors for ion sources at RCNP

    Science.gov (United States)

    Yorita, T.; Hatanaka, K.; Fukuda, M.; Shimada, K.; Yasuda, Y.; Saito, T.; Tamura, H.; Kamakura, K.

    2016-02-01

    Recently, several developments of low energy beam transport line and its beam diagnostic systems have been performed to improve the injection efficiency of ion beam to azimuthally varying field cyclotron at Research Center for Nuclear Physics, Osaka University. One of those is the fast emittance monitor which can measure within several seconds for the efficient beam development and a Pepper-Pot Emittance Monitor (PPEM) has been developed. The PPEM consists of pepper-pot mask, multichannel plate, fluorescent screen, mirror, and CCD camera. The CCD image is taken via IEEE1394b to a personal computer and analyzed immediately and frequently, and then real time measurement with about 2 Hz has been achieved.

  6. Emittance preservation during bunch compression with a magnetized beam

    Science.gov (United States)

    Stratakis, Diktys

    2016-03-01

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based in combining a finite solenoid field where the beam is generated with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth from CSR can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  7. Rapid determination of gross alpha/beta activity in milk using liquid scintilation counter technique

    Directory of Open Access Journals (Sweden)

    Sas Daniel

    2016-01-01

    Full Text Available Rapid determination of gross alpha and beta emitters in milk by liquid scintillation counter is discussed. This method is based on direct addition of different types of milk into scintillation cocktail and therefore it is very promising for fast determination of alpha/beta activity due to direct alpha and beta separation, measurement in close 4p geometry and without sample treatment. The selected group of radionuclides was chosen with the respect to military significance, radio-toxicity, and possibility of potential misuse. As model radionuclides 241Am, 239Pu, and 90Sr were selected. The Liquid Scintilation Counter Hidex 300 SL equipped with triple-double-coincidence-ratio technique was used for sample measurement. The aim of the work was focused on comparison of different cocktails produced by Hidex and Perkin Elmer, choosing the best cocktail based on our measurement results and adjustment of its appropriate volume. Furthermore, the optimization of ratio between the volume of scintillation cocktail and the volume of urine was investigated with the respect to the model radionuclides. According to the obtained results, the efficiency for alpha emitters was greater than 85% and for beta, greater than 95%. The obtained results allowed this method to be used for rapid determination of gross alpha/beta activity in cases where time is an essence, such as first responders or mass-scale samples, where ordinary means suffer from lack of capacity or simply collapse under the onslaught.

  8. Impact of water temperature and structural parameters on the hydraulic labyrinth-channel emitter performance

    Directory of Open Access Journals (Sweden)

    Ahmed I. Al-Amoud

    2014-06-01

    Full Text Available The effects of water temperature and structural parameters of a labyrinth emitter on drip irrigation hydraulic performance were investigated. The inside structural parameters of the trapezoidal labyrinth emitter include path width (W and length (L, trapezoidal unit numbers (N, height (H, and spacing (S. Laboratory experiments were conducted using five different types of labyrinth-channel emitters (three non-pressure compensating and two pressure-compensating emitters commonly used for subsurface drip irrigation systems. The water temperature effect on the hydraulic characteristics at various operating pressures was recorded and a comparison was made to identify the most effective structural parameter on emitter performance. The pressure compensating emitter flow exponent (x average was 0.014, while non-pressure compensating emitter’s values average was 0.456, indicating that the sensitivity of non-pressure compensating emitters to pressure variation is an obvious characteristic (p<0.001 of this type of emitters. The effects of water temperature on emitter flow rate were insignificant (p>0.05 at various operating pressures, where the flow rate index values for emitters were around one. The effects of water temperature on manufacturer’s coefficient of variation (CV values for all emitters were insignificant (p>0.05. The CV values of the non-pressure compensating emitters were lower than those of pressure compensating emitters. This is typical for most compensating models because they are manufactured with more elements than non-compensating emitters are. The results of regression analysis indicate that N and H are the essential factors (p<0.001 to affect the hydraulic performance.

  9. T-Shaped Emitter Metal Structures for HBTs

    Science.gov (United States)

    Fung, King Man; Samoska, Lorene; Velebir, James; Muller, Richard; Echternach, Pierre; Siegel, Peter; Smith, Peter; Martin, Suzanne; Malik, Roger; Rodwell, Mark; Urteaga, Miguel; Paidi, Vamsi; Griffith, Zack

    2006-01-01

    Metal emitter structures in a class of developmental InP-based high-speed heterojunction bipolar transistors (HBTs) have been redesigned to have T-shaped cross sections. T-cross-section metal features have been widely used in Schottky diodes and high-electron-mobility transistors, but not in HBTs. As explained, the purpose served by the present T cross-sectional shapes is to increase fabrication yields beyond those achievable with the prior cross-sectional shapes.

  10. Industrial application of electron sources with plasma emitters

    CERN Document Server

    Belyuk, S I; Rempe, N G

    2001-01-01

    Paper contains a description, operation, design and parameters of electron sources with plasma emitters. One presents examples of application of these sources as part of automated electron-beam welding lines. Paper describes application of such sources for electron-beam deposition of composite powders. Electron-beam deposition is used to rebuild worn out part and to increase strength of new parts of machines and tools. Paper presents some examples of rebuilding part and the advantages gained in this case

  11. Directional couplers with integrated carbon nanotube incandescent light emitters

    OpenAIRE

    Fechner, Randy G.; Pyatkov, Felix; Khasminskaya, Svetlana; Flavel, Benjamin S.; Krupke, Ralph; Pernice, Wolfram H. P.

    2016-01-01

    We combine on-chip single-walled carbon nanotubes (SWNTs) emitters with directional coupling devices as fundamental building blocks for carbon photonic systems. These devices are essential for studying the emission properties of SWNTs in the few photon regime for future applications in on-chip quantum photonics. The combination of SWNTs with on-chip beam splitters herein provides the basis for correlation measurements as necessary for nanoscale source characterization. The employed fabricatio...

  12. Resonantly enhanced thermal emitters based on nanophotonic structures

    OpenAIRE

    O'Regan, Bryan J.

    2015-01-01

    The manipulation of photons, especially the control of spontaneous emission, has become a core area of photonics research in the 21st century. One of the key challenges is the control of the broadband emission profile of thermal emitters. Recently, attention has focused on resonant nanophotonic structures to control the thermal emission with most of the work concentrating on the mid-infrared wavelength range and/or based on metallic nanostructures. However, the realisation of a high temperatu...

  13. Dynamical Properties of Nanolasers Based on Few Discrete Emitters

    DEFF Research Database (Denmark)

    Lund, Anders Mølbjerg; Nielsen, Per Kær; Lorke, Michael;

    2013-01-01

    analytically express the response of the nanolaser to a modulation of the pumping rate. These results are compared with the modulation response obtained directly from the master equation using a novel method. We show that contrary to conventional semiconductor lasers, the nanolaser is typically over-damped and...... displays a dip in the modulation bandwidth as the two-level systems become inverted. Both these features can be traced back to the use of discrete emitters that are incoherently pumped....

  14. Two-dimensional VO2 photonic crystal selective emitter

    International Nuclear Information System (INIS)

    The design and simulation of a two-dimensional (2D) photonic crystal (PhC) selective emitter made of vanadium dioxide (VO2), a type metal oxide with a high temperature resistance, are reported. Spectral emission characteristics of the 2D VO2 PhCs were investigated using the finite difference time domain (FDTD) method. The PhC consists of a periodic array of cylindrical air microcavities. The influences of the geometric characteristic parameters are discussed. The influences of the radius and depth on the emission of the 2D VO2 PhC can be explained based on the coupled-mode theory. The emissivities at wavelengths below the cut-off wavelength were enhanced by increasing the depth. When the depth was much larger than the radius, the cut-off wavelength increased with the radius. The effect of the period on the emissivity at wavelengths less than the period was highly influenced by the diffraction modes. The designed 2D VO2 PhC emitter exhibited a selective emission that was well-matched with InGaAs cells. The spectral emissivities within the convertible wavelength range of the InGaAs cells reached 0.95, and the emissivities for non-convertible wavelengths were less than 0.3. - Highlights: • The lattice structure of metal phase VO2 does not change with temperature. • The influences of scales on the emission of a 2D VO2 PhC are discussed. • A 2D VO2 photonic crystal emitter matched well with InGaAs cell is designed. • The matched VO2 PhC emitter can highly improve the TPV system efficiency

  15. Strong coupling between surface plasmon polaritons and emitters

    OpenAIRE

    Törmä, P.; Barnes, W.L.

    2014-01-01

    In this review we look at the concepts and state-of-the-art concerning the strong coupling of surface plasmon-polariton modes to states associated with quantum emitters such as excitons in J-aggregates, dye molecules and quantum dots. We explore the phenomenon of strong coupling with reference to a number of examples involving electromagnetic fields and matter. We then provide a concise description of the relevant background physics of surface plasmon polaritons. An extensive overview of the ...

  16. Use of beam emittance measurements in matching problems

    International Nuclear Information System (INIS)

    The CERN new 50 MeV linac should operate with a computer-aided beam matching in which the transverse criteria are based on measured r.m.s. values of beam co-ordinates in phase space. The collected data, however, need to undergo an intermediate treatment before significant results can be obtained and then used in computations. Some examples from the experimental study programme are given and the role of automated beam emittance measurements in matching problems discussed. (author)

  17. Emittance coupling driven by space charge in the CSNS linac

    Institute of Scientific and Technical Information of China (English)

    YIN Xue-Jun; FU Shi-Nian; PENG Jun

    2009-01-01

    In the conventional design of RF linacs, the bunched beams are not in thermal equilibrium. The space charge forces couple the particle motions between the transverse and the longitudinal directions. Fur-thermore it will cause the equipartitioning process which leads to emittance growth and halo formation. In the design of the China Spallation Neutron Source (CSNS) linac, three cases are investigated using the Hofmann stability charts. In this paper, we present the equipartitioning beam study of the CSNS Alvarez DTL linac.

  18. Electron Emission from Ultra-Large Area MOS Electron Emitters

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm;

    2009-01-01

    Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from....... Electron emission under high pressures (up to 2 bars) of Ar was observed. ©2009 American Vacuum Society...

  19. Sounding Rocket Telemetry Emitter, MID Antenna and Ground Receiver Antennas

    OpenAIRE

    Marque, Alexandre; Ghiotto, Anthony

    2015-01-01

    IEEE MTT-S Undergraduate Scholarships Reports The goal of this research project is to design a complete 2.45 GHz data link for telemetry application between a sounding rocket and a ground station. The emission part is embedded in the rocket and has a lot of mechanical constraints. The design for the emitter, the rocket antenna and the ground station receiver are detailed.

  20. Photon pair source via two coupling single quantum emitters

    Institute of Scientific and Technical Information of China (English)

    彭勇刚; 郑雨军

    2015-01-01

    We study the two coupling two-level single molecules driven by an external field as a photon pair source. The proba-bility of emitting two photons, P2, is employed to describe the photon pair source quality in a short time, and the correlation coefficient RAB is employed to describe the photon pair source quality in a long time limit. The results demonstrate that the coupling single quantum emitters can be considered as a stable photon pair source.

  1. Cooperative Lamb shift in a quantum emitter array

    OpenAIRE

    Meir, Ziv; Schwartz, Osip; Shahmoon, Ephraim; Oron, Dan; Ozeri, Roee

    2013-01-01

    Whenever several quantum light emitters are brought in proximity with one another, their interaction with common electromagnetic fields couples them, giving rise to cooperative shifts in their resonance frequency. Such collective line shifts are central to modern atomic physics, being closely related to superradiance on one hand and the Lamb shift on the other. Although collective shifts have been theoretically predicted more than fifty years ago, the effect has not been observed yet in a con...

  2. Fitting of alpha-efficiency versus quenching parameter by exponential functions in liquid scintillation counting

    Energy Technology Data Exchange (ETDEWEB)

    Sosa, M. [Departamento de Ingeniería Física, Campus León, Universidad de Guanajuato, 37150 León, Guanajuato (Mexico); Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain); Manjón, G., E-mail: manjon@us.es [Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain); Mantero, J.; García-Tenorio, R. [Universidad de Sevilla, Departamento de Física Aplicada II, E.T.S. Arquitectura, Av. Reina Mercedes, 2, 41012 Sevilla (Spain)

    2014-05-01

    The objective of this work is to propose an exponential fit for the low alpha-counting efficiency as a function of a sample quenching parameter using a Quantulus liquid scintillation counter. The sample quenching parameter in a Quantulus is the Spectral Quench Parameter of the External Standard (SQP(E)), which is defined as the number of channel under which lies the 99% of Compton spectrum generated by a gamma emitter ({sup 152}Eu). Although in the literature one usually finds a polynomial fitting of the alpha counting efficiency, it is shown here that an exponential function is a better description. - Highlights: • We have studied the quenching in alpha measurement by liquid scintillation counting. • We have reviewed typical fitting of alpha counting efficiency versus quenching parameter. • Exponential fitting of data is proposed as better fitting. • We consider exponential fitting has a physical basis.

  3. Anti-cluster Decay and Anti-alpha Decay of Antimatter nuclei

    CERN Document Server

    Poenaru, D N; Greiner, W

    2015-01-01

    A broad extension of periodic system into the sector of antimatter could be possible sometimes in a remote future. We expect that anti-alpha spontaneous emission from an antimatter nucleus will have the same Q-value and half-life as alpha emission from the corresponding mirror nucleus. This is the consequence of the invariance of binding energy as well as of the surface and Coulomb energy when passing from matter to antimatter nuclei with the the same mass number and the same atomic number. The Q-values and half-lives of all measured up to now 27 cluster radioactivities are given together with Q-values and half-lives of the most important competitor --- $\\alpha$ decay. The lightest anti-alpha emitter, $^8\\bar{Be}$, will have a very short half-life of about $81.9\\cdot 10^{-18}$ s.

  4. Fitting of alpha-efficiency versus quenching parameter by exponential functions in liquid scintillation counting

    International Nuclear Information System (INIS)

    The objective of this work is to propose an exponential fit for the low alpha-counting efficiency as a function of a sample quenching parameter using a Quantulus liquid scintillation counter. The sample quenching parameter in a Quantulus is the Spectral Quench Parameter of the External Standard (SQP(E)), which is defined as the number of channel under which lies the 99% of Compton spectrum generated by a gamma emitter (152Eu). Although in the literature one usually finds a polynomial fitting of the alpha counting efficiency, it is shown here that an exponential function is a better description. - Highlights: • We have studied the quenching in alpha measurement by liquid scintillation counting. • We have reviewed typical fitting of alpha counting efficiency versus quenching parameter. • Exponential fitting of data is proposed as better fitting. • We consider exponential fitting has a physical basis

  5. Targeted alpha-therapy using [Bi-213]anti-CD20 as novel treatment option for radio- and chemoresistant non-Hodgkin lymphoma cells

    OpenAIRE

    Roscher, Mareike; Hormann, Inis; Leib, Oliver; Marx, Sebastian; Moreno, Josue; Miltner, Erich; Friesen, Claudia

    2013-01-01

    Radioimmunotherapy (RIT) is an emerging treatment option for non-Hodgkin lymphoma (NHL) producing higher overall response and complete remission rates compared with unlabelled antibodies. However, the majority of patients treated with conventional or myeloablative doses of radiolabelled antibodies relapse. The development of RIT with alpha-emitters is attractive for a variety of cancers because of the high linear energy transfer (LET) and short path length of alpha-radiation in human tissue, ...

  6. The alpha channeling effect

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, N. J.

    2015-12-10

    Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a way that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.

  7. Gas ionization sensors with carbon nanotube/nickel field emitters.

    Science.gov (United States)

    Huang, Bohr-Ran; Lin, Tzu-Ching; Yang, Ying-Kan; Tzeng, Shien-Der

    2011-12-01

    Gas ionization sensors based on the field emission properties of the carbon nanotube/nickel (CNT/Ni) field emitters were first developed in this work. It is found that the breakdown electric field (E(b)) slightly decreases from 2.2 V/microm to 1.9 V/microm as the pressure of H2 gas increases from 0.5 Torr to 100 Torr. On the contrary, E(b) obviously increases from 2.9 V/microm to 6.5 V/microm as O2 gas pressure increases from 0.5 Torr to 100 Torr. This may be explained by the depression of the electron emission that caused by the adsorption of the O2 gas on the CNT emitters. The Raman spectra of the CNT/Ni emitters also show that more defects were generated on the CNTs after O2 gas sensing. The Joule heating effect under high current density as performing H2 sensing was also observed. These effects may contribute the pressure dependence on the breakdown electric field of the CNT/Ni gas ionization sensors. PMID:22409010

  8. Biologic data, models, and dosimetric methods for internal emitters

    International Nuclear Information System (INIS)

    The absorbed radiation dose from internal emitters has been and will remain a pivotal factor in assessing risk and therapeutic utility in selecting radiopharmaceuticals for diagnosis and treatment. Although direct measurements of absorbed dose and dose distributions in vivo have been and will continue to be made in limited situations, the measurement of the biodistribution and clearance of radiopharmaceuticals in human subjects and the use of this data is likely to remain the primary means to approach the calculation and estimation of absorbed dose from internal emitters over the next decade. Since several approximations are used in these schema to calculate dose, attention must be given to inspecting and improving the application of this dosimetric method as better techniques are developed to assay body activity and as more experience is gained in applying these schema to calculating absorbed dose. Discussion of the need for considering small scale dosimetry to calculate absorbed dose at the cellular level will be presented in this paper. Other topics include dose estimates for internal emitters, biologic data mathematical models and dosimetric methods employed. 44 refs

  9. Superconducting wiggler magnets for beam-emittance damping rings

    CERN Document Server

    Schoerling, Daniel

    2012-01-01

    Ultra-low emittance beams with a high bunch charge are necessary for the luminosity performance of linear electron-positron colliders, such as the Compact Linear Collider (CLIC). An effective way to create ultra-low emittance beams with a high bunch charge is to use damping rings, or storage rings equipped with strong damping wiggler magnets. The remanent field of the permanent magnet materials and the ohmic losses in normal conductors limit the economically achievable pole field in accelerator magnets operated at around room temperature to below the magnetic saturation induction, which is 2.15 T for iron. In wiggler magnets, the pole field in the center of the gap is reduced further like the hyperbolic cosine of the ratio of the gap size and the period length multiplied by pi. Moreover, damping wiggler magnets require relatively large gaps because they have to accept the un-damped beam and to generate, at a small period length, a large magnetic flux density amplitude to effectively damp the beam emittance....

  10. Low Emittance Gun Project based on Field Emission

    CERN Document Server

    Ganter, Romain; Dehler, M; Gobrecht, Jens; Gough, Chris; Ingold, Gerhard; Leemann, Simon C; Shing-Bruce-Li, Kevin; Paraliev, Martin; Pedrozzi, Marco; Raguin, Jean Yves; Rivkin, Leonid; Schlott, Volker; Sehr, Harald; Streun, Andreas; Wrulich, Albin F; Zelenika, Sasa

    2004-01-01

    The design of an electron gun capable of producing beam emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser emitting at 0.1nm. Field emitter arrays (FEAs) including a gate and a focusing layer are an attractive technology for such high brightness sources. Electrons are extracted from micrometric tips thanks to voltage pulses between gate and tips. The focusing layer should then reduce the initial divergence of each emitted beamlets. This FEA will be inserted in a high gradient diode configuration coupled with a radiofrequency structure. In the diode part very high electric field pulses (several hundreds of MV/m) will limit the degradation of emittance due to space charge effect. This first acceleration will be obtained with high voltage pulses (typically a megavolt in a few hundred of nanoseconds) synchronized with the low voltage pulses applied to the FEA (typically one hundred of volts in one nanosecond at frequency below kilohe...

  11. The Next Generation Photoinjector (thermal Emittance, Quantum Efficiency)

    CERN Document Server

    Palmer, D T

    1998-01-01

    This dissertation will elucidate the design, construction, theory, and operation of the Next Generation Photoinjector (NGP). This photoinjector is comprised of the BNL/SLAC/UCLA 1.6 cell symmetrized S-band photocathode radio frequency (rf) electron gun and a single emittance-compensation solenoidal magnet. This photoinjector is a prototype for the Linear Coherent Light Source X-ray Free Electron Laser operating in the 1.5 A range. Simulations indicate that this photoinjector is capable of producing a 1 nC electron bunch with transverse normalized emittance less than 1 $\\pi$ mm-mrad were the cathode is illuminated with a 10 psec longitudinal flat top pulse. Using a Gaussian longitudinal laser profile with a full width half maximum (FWHM) of 10 psec, simulation indicates that the NGP is capable of producing a normalized rms emittance of 2.50 $\\pi$ mm-mrad at 1 nC. Using the removable cathode plate we have studied the quantum efficiency (QE) of both copper and magnesium photo-cathodes...

  12. Variable Emittance Electrochromic Devices for Satellite Thermal Control

    Science.gov (United States)

    Demiryont, Hulya; Shannon, Kenneth C.

    2007-01-01

    An all-solid-state electrochromic device (ECD) was designed for electronic variable emissivity (VE) control. In this paper, a low weight (5g/m2) electrochromic thermal control device, the EclipseVEECD™, is detailed as a viable thermal control system for spacecraft outer surface temperatures. Discussion includes the technology's performance, satellite applications, and preparations for space based testing. This EclipseVEECD™ system comprises substrate/mirror electrode/active element/IR transparent electrode layers. This system tunes and modulates reflection/emittance from 5 μm to 15 μm region. Average reflectance/emittance modulation of the system from the 400 K to 250 K region is about 75%, while at room temperature (9.5 micron) reflectance/emittance is around 90%. Activation voltage of the EclipseVEECD™ is around ±1 Volt. The EclipseVEECD™ can be used as a smart thermal modulator for the thermal control of satellites and spacecraft by monitoring and adjusting the amount of energy emitted from the outer surfaces. The functionality of the EclipseVEECD™ was successfully demonstrated in vacuum using a multi-purpose heat dissipation/absorption test module, the EclipseHEAT™. The EclipseHEAT™ has been successfully flight checked and integrated onto the United States Naval Alchemy MidSTAR satellite, scheduled to launch December 2006.

  13. The relevance of dose for low-energy beta emitters

    International Nuclear Information System (INIS)

    Specific issues in risk assessment for low-energy beta emitters include specification of the radiation weighting factor, values of relative biological effectiveness for specific or accurate risk estimates, non-uniformities of dose within tissues and cells, and use of standard tissue weighting factors for non-uniform situations. Unusual features of low-energy beta emitters include: increased average ionisation density on subcellular (and cellular) scales; short ranges of the beta electrons; non-uniformity of the absorbed dose over subcellular, cellular, and tissue dimensions; reduced hit frequencies; nuclear transmutations; different chemical forms, influencing biokinetics and dose distributions; and large isotopic mass differences, particularly in the case of tritium and hydrogen. Many of these features are not included explicitly in conventional radiation protection dosimetry, although they may be partly included in experimental determinations of relative biological effectiveness. Theoretical and experimental studies have shown low-energy electrons to be particularly efficient in producing double-strand breaks in DNA, including complex double-strand breaks. Hence, on fundamental grounds, tritium beta particles should be expected to have greater biological effectiveness per unit absorbed dose than 60Co gamma-rays or orthovoltage x-rays. For practical purposes, and in view of the paucity of epidemiological estimates of risk from low-energy electrons, consideration should be given to applying a raised relative biological effectiveness, say of value 2, to all low-energy internal emitters, including beta particles and soft x-ray emissions.

  14. Emittance Measurement for Beamline Extension at the PET Cyclotron

    Directory of Open Access Journals (Sweden)

    Sae-Hoon Park

    2016-01-01

    Full Text Available Particle-induced X-ray emission is used for determining the elemental composition of materials. This method uses low-energy protons (of several MeV, which can be obtained from high-energy (of tens MeV accelerators. Instead of manufacturing an accelerator for generating the MeV protons, the use of a PET cyclotron has been suggested for designing the beamline for multipurpose applications, especially for the PIXE experiment, which has a dedicated high-energy (of tens MeV accelerator. The beam properties of the cyclotron were determined at this experimental facility by using an external beamline before transferring the ion beam to the experimental chamber. We measured the beam profile and calculated the emittance using the pepper-pot method. The beam profile was measured as the beam current using a wire scanner, and the emittance was measured as the beam distribution at the beam dump using a radiochromic film. We analyzed the measurement results and are planning to use the results obtained in the simulations of external beamline and aligned beamline components. We will consider energy degradation after computing the beamline simulation. The experimental study focused on measuring the emittance from the cyclotron, and the results of this study are presented in this paper.

  15. Importance of salt in the production matrix of the efficiency curve for the determination of the total alpha activity in water samples; Importancia de la matriz salina en la fabricacion de la curva de eficiencia para la determinacion del indice de actividad alfa total en muestras de agua

    Energy Technology Data Exchange (ETDEWEB)

    Baeza, A.; Corbacho, J. A.

    2011-07-01

    The determination of total alpha activity by the evaporation method allows obtaining, from a quick and inexpensive technique, the order of magnitude of the total activity of all alpha emitters present in a sample of water. This study shows that the detection efficiency curve varies significantly depending on the sodium salt is used to manufacture calibration and/or reference radionuclide used. (Author)

  16. Survey Musik und Medien 2012: Audio Media Usage in Germany - Audio Emitters - Audio Emitters in used in 2012

    OpenAIRE

    Lepa, Steffen

    2013-01-01

    Where did the sound emanate from in 2012? Audio Emitters comprise those technical objects that are connected to Audio Devices in order to make Audio Sources audible. This category includes headphones and loudspeakers with both diverse sound formats (mono, stereo, surround) as well as various device types (Headphones: small, standard, HiFi; Loudspeakers: integrated models, single components and docking stations). How do the Germans listen to music nowadays? Survey Musik und Medien 2012 deli...

  17. Survey Musik und Medien 2012: Audio Media Usage in Germany - Audio Emitters - Audio Emitters used in 2012 - Versatile Traditionalists

    OpenAIRE

    Lepa, Steffen

    2013-01-01

    Where did the sound emanate from in 2012? Audio Emitters comprise those technical objects that are connected to Audio Devices in order to make Audio Sources audible. This category includes headphones and loudspeakers with both diverse sound formats (mono, stereo, surround) as well as various device types (Headphones: small, standard, HiFi; Loudspeakers: integrated models, single components and docking stations). Versatile Traditionalists constitute the most prevalent audio repertoire with...

  18. Survey Musik und Medien 2012: Audio Media Usage in Germany - Audio Emitters - Audio Emitters used in 2012 - Radio Traditionalists

    OpenAIRE

    Lepa, Steffen

    2013-01-01

    Where did the sound emanate from in 2012? Audio Emitters comprise those technical objects that are connected to Audio Devices in order to make Audio Sources audible. This category includes headphones and loudspeakers with both diverse sound formats (mono, stereo, surround) as well as various device types (Headphones: small, standard, HiFi; Loudspeakers: integrated models, single components and docking stations). Radio Traditionalists are represented in various age groups, and may be born ...

  19. Local versus nonlocal $\\alpha\\alpha$ interactions in $3\\alpha$ description of $^{12}$C

    CERN Document Server

    Suzuki, Y; Descouvemont, P; Fujiwara, Y; Matsumura, H; Orabi, M; Theeten, M

    2008-01-01

    Local $\\alpha \\alpha$ potentials fail to describe $^{12}$C as a $3\\alpha$ system. Nonlocal $\\alpha \\alpha$ potentials that renormalize the energy-dependent kernel of the resonating group method allow interpreting simultaneously the ground state and $0^+_2$ resonance of $^{12}$C as $3\\alpha$ states. A comparison with fully microscopic calculations provides a measure of the importance of three-cluster exchanges in those states.

  20. Bremsstrahlung in $\\alpha$ Decay

    CERN Document Server

    Takigawa, N; Hagino, K; Ono, A; Brink, D M

    1999-01-01

    A quantum mechanical analysis of the bremsstrahlung in $\\alpha$ decay of $^{210}$Po is performed in close reference to a semiclassical theory. We clarify the contribution from the tunneling, mixed, outside barrier regions and from the wall of the inner potential well to the final spectral distribution, and discuss their interplay. We also comment on the validity of semiclassical calculations, and the possibility to eliminate the ambiguity in the nuclear potential between the alpha particle and daughter nucleus using the bremsstrahlung spectrum.

  1. ALPHA-2: the sequel

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    While many experiments are methodically planning for intense works over the long shutdown, there is one experiment that is already working at full steam: ALPHA-2. Its final components arrived last month and will completely replace the previous ALPHA set-up. Unlike its predecessor, this next generation experiment has been specifically designed to measure the properties of antimatter.   The ALPHA team lower the new superconducting solenoid magnet into place. The ALPHA collaboration is working at full speed to complete the ALPHA-2 set-up for mid-November – this will give them a few weeks of running before the AD shutdown on 17 December. “We really want to get some experience with this device this year so that, if we need to make any changes, we will have time during the long shutdown in which to make them,” says Jeffrey Hangst, ALPHA spokesperson. “Rather than starting the 2014 run in the commissioning stage, we will be up and running from the get go.&...

  2. A Deep Hubble Space Telescope and Keck Search for Definitive Identification of Lyman Continuum Emitters at z~3.1

    Science.gov (United States)

    Siana, Brian; Shapley, Alice E.; Kulas, Kristin R.; Nestor, Daniel B.; Steidel, Charles C.; Teplitz, Harry I.; Alavi, Anahita; Brown, Thomas M.; Conselice, Christopher J.; Ferguson, Henry C.; Dickinson, Mark; Giavalisco, Mauro; Colbert, James W.; Bridge, Carrie R.; Gardner, Jonathan P.; de Mello, Duilia F.

    2015-05-01

    Narrowband imaging of the rest-frame Lyman continuum (LyC) of galaxies at z∼ 3.1 has produced a large number of candidate LyC-emitting galaxies. These samples are contaminated by galaxies at lower redshift. To better understand LyC escape, we need an uncontaminated sample of galaxies that emit strongly in the LyC. Here we present deep Hubble Space Telescope imaging of five bright galaxies at z∼ 3.1 that had previously been identified as candidate LyC emitters with ground-based images. The WFC3 F336W images probe the LyC of galaxies at z\\gt 3.06 and provide an order-of-magnitude increase in spatial resolution over ground-based imaging. The non-ionizing UV images often show multiple galaxies (or components) within ∼ 1\\prime\\prime of the candidate LyC emission seen from the ground. In each case, only one of the components is emitting light in the F336W filter, which would indicate LyC escape if that component is at z\\gt 3.06. We use Keck/NIRSPEC near-IR spectroscopy to measure redshifts of these components to distinguish LyC emitters from foreground contamination. We find that two candidates are low-redshift contaminants, one candidate had a previously misidentified redshift, and the other two cannot be confirmed as LyC emitters. The level of contamination is consistent with previous estimates. For the galaxies with z\\gt 3.06, we derive strong 1σ limits on the relative escape fraction between 0.07 and 0.09. We still do not have a sample of definitive LyC emitters, and a much larger study of low-luminosity galaxies is required. The combination of high-resolution imaging and deep spectroscopy is critical for distinguishing LyC emitters from foreground contaminants. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the

  3. Resting alpha activity predicts learning ability in alpha neurofeedback

    OpenAIRE

    Wenya eNan; Feng eWan; Mang I eVai; Agostinho eRosa

    2014-01-01

    Individuals differ in their ability to learn how to regulate the alpha activity by neurofeedback. This study aimed to investigate whether the resting alpha activity is related to the learning ability of alpha enhancement in neurofeedback and could be used as a predictor. A total of 25 subjects performed 20 sessions of individualized alpha neurofeedback in order to learn how to enhance activity in the alpha frequency band. The learning ability was assessed by three indices respectively: the tr...

  4. Alpha particles in fusion research

    International Nuclear Information System (INIS)

    This collection of 39 (mostly view graph) presentations addresses various aspects of alpha particle physics in thermonuclear fusion research, including energy balance and alpha particle losses, transport, the influence of alpha particles on plasma stability, helium ash, the transition to and sustainment of a burning fusion plasma, as well as alpha particle diagnostics. Refs, figs and tabs

  5. Thinking Critically about Critical Thinking

    Science.gov (United States)

    Mulnix, Jennifer Wilson

    2012-01-01

    As a philosophy professor, one of my central goals is to teach students to think critically. However, one difficulty with determining whether critical thinking can be taught, or even measured, is that there is widespread disagreement over what critical thinking actually is. Here, I reflect on several conceptions of critical thinking, subjecting…

  6. Investigation of the high-spin rotational properties of the proton emitter $^{113}$Cs using a particle-number conserving method

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The recently observed two high-spin rotational bands in the proton emitter $^{113}$Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 ($\\pi 3/2^+[422], \\alpha = -1/2$) and band 2 ($\\pi 1/2^+[420], \\alpha = 1/2$), the experimental moments of inertia and quasiparticle alignments can be well reproduced by the present calculations, which in turn strongly support these configuration assignments. Furthermore, by analyzing the occupation probability $n_\\mu$ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.

  7. Radiobiological long-term accumulation of environmental alpha radioactivity in extracted human teeth and animal bones in Malaysia

    International Nuclear Information System (INIS)

    In this study, the radiobiological analysis of natural alpha emitters in extracted human teeth and animal bones from Malaysia was estimated. The microdistributions of alpha particles in tooth and bone samples were measured using CR-39 alpha-particle track detectors. The lowest and highest alpha emission rates in teeth in the Kedah and Perak states were 0.0080 ± 0.0005 mBq cm−2 and 0.061 ± 0.008 mBq cm−2, whereas those of bones in the Perlis and Kedah states were 0.0140 ± 0.0001 mBq cm−2 and 0.7700 ± 0.0282 mBq cm−2, respectively. The average alpha emission rate in male teeth was 0.0209 ± 0.0008 mBq cm−2, whereas that of female teeth was 0.0199 ± 0.0010 mBq cm−2. The alpha emission rate in teeth is higher in smokers (0.0228 ± 0.0008 mBq cm−2) than in non-smokers (0.0179 ± 0.0008 mBq cm−2). Such difference was found statistically significant (p < 0.01). - Highlights: • Alpha emission rates in teeth from smokers slightly higher than non-smokers. • Difference between alpha rates in male and female tooth not statistically significant. • Alpha particles have the same effect at any age. • Difference between alpha rates in bones was statistically significant

  8. Dependence of optimal spacing on applied field in ungated field emitter arrays

    Directory of Open Access Journals (Sweden)

    J. R. Harris

    2015-08-01

    Full Text Available In ungated field emitter arrays, the field enhancement factor β of each emitter tip is reduced below the value it would have in isolation due to the presence of adjacent emitters, an effect known as shielding or screening. Reducing the distance b between emitters increases the density of emission sites, but also reduces the emission per site, leading to the existence of an optimal spacing that maximizes the array current. Most researchers have identified that this optimal spacing is comparable to the emitter height h, although there is disagreement about the exact optimization. Here, we develop a procedure to determine the dependence of this optimal spacing on the applied electric field. It is shown that the nature of this dependence is governed by the shape of the β(b curve, and that for typical curves, the optimal value of the emitter spacing b decreases as the applied field increases.

  9. Surface Analysis of LaB6 Single Crystal Thermionic Emitters

    Science.gov (United States)

    Nakazawa, Masatoshi; Futamoto, Masaaki; Hosoki, Shigeyuki; Usami, Katuhisa

    1980-07-01

    Surface analysis of heated LaB6 thermionic emitter is made by means of Auger electron spectroscopy. Changes in surface state with changing emitter temperature and ambient oxygen pressure are investigated. The emitter temperature is varied from room temperature to 1700°C, and the oxygen pressure from 1× 10-5 Pa to 7× 10-3 Pa. With the increase of temperature the emitter surface passes through four states depending on oxygen pressure, before it reaches a clean state. Among them a state is particularly noteworthy that the emitter surface is covered with a layer of lanthanum oxide just before assuming the clean surface state. A surface state diagram is shown. The optimum conditions of emitter temperature and oxygen gas pressure to exhibit high emission properties are described.

  10. Reduction of bend-plane emittance growth in a chicane pulse compressor

    CERN Document Server

    Dowell, D H

    1999-01-01

    Emittance preservation in beam bending systems is vitally important in the production of bright, high-current electron microbunches. Generally, the emittance increase occurs in the bend plane and results from changes in the microbunch energy distribution as the beam transits the bend. This redistribution of electron energies increases the beam's divergence, and hence the emittance, by spoiling the achromatic transport of the bending system. In this paper we investigate the correlated emittance growth in a three dipole chicane compressor due to coherent synchrotron radiation (CSR). Breaking the symmetry of the chicane partially cancels the CSR-induced correlation thereby reducing the bend plane emittance growth. The consequences of this emittance compensation scheme are discussed.

  11. Radial arrays of nano-electrospray ionization emitters and methods of forming electrosprays

    Science.gov (United States)

    Kelly, Ryan T [West Richland, WA; Tang, Keqi [Richland, WA; Smith, Richard D [Richland, WA

    2010-10-19

    Electrospray ionization emitter arrays, as well as methods for forming electrosprays, are described. The arrays are characterized by a radial configuration of three or more nano-electrospray ionization emitters without an extractor electrode. The methods are characterized by distributing fluid flow of the liquid sample among three or more nano-electrospray ionization emitters, forming an electrospray at outlets of the emitters without utilizing an extractor electrode, and directing the electrosprays into an entrance to a mass spectrometry device. Each of the nano-electrospray ionization emitters can have a discrete channel for fluid flow. The nano-electrospray ionization emitters are circularly arranged such that each is shielded substantially equally from an electrospray-inducing electric field.

  12. Effects of space charge on the current-voltage characteristics of field emitter arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K.L.; Zaidman, E.G.; Kodis, M.A. [Naval Research Laboratory, Washington, District of Columbia. 20375 (United States)

    1997-02-01

    Field emitter arrays are microfabricated very high electron current density sources. For rf amplifier applications, typical current densities are typically on the order of 100Amps/cm{sup 2}. Unlike thermionic emitters, the current densities at the emission sites on field emitters can approach 10{sup 8}Amps/cm{sup 2} at high fields. Consequently, the high current from the array can affect the I(V) characterization of the emitters. In this manuscript, we use a simple model of a field emitter to calculate the one dimensional space charge effects on the current versus gate voltage characteristics. Two effects are treated: charge between the gate and anode, and charge within the FEA unit cell, which gives rise to a new space charge component. It is shown that space charge effects can taint the Fowler Nordheim parametrization of field emitters and consequently affect the estimates of their transconductance. {copyright} {ital 1997 American Institute of Physics.}

  13. In situ measurements of the spectral emittance of coal ash deposits

    International Nuclear Information System (INIS)

    The spectral emittance of deposits left by bituminous and sub-bituminous coals under oxidizing conditions have been measured in situ. Pulverized coal is injected into a down-fired entrained-flow reactor. Ash accumulates on a probe in the reactor effluent and radiation emitted by the ash layer is recorded using a Fourier transform infrared (FTIR) spectrometer. Values for the spectral emissive power emitted by the ash and the surface temperature of the ash are extracted from these data. These results are then used to calculate the spectral emittance of the deposit. The spectral emittances of ash deposits formed by burning Illinois no. 6 (bituminous) coal and Powder River Basin (sub-bituminous) coal were measured between 3000 and 500 wavenumbers. The spectral emittance of the deposit left by the bituminous coal has a constant value of approximately 0.46 between 3000 and 2400 wavenumbers. Between 2200 and 1200 wavenumbers, the spectral emittance of the deposit increases from approximately 0.47 to approximately 0.61. Between 1200 and 500 wavenumbers, the spectral emittance is relatively constant at 0.61. The spectral emittance of the deposit left by the sub-bituminous coal is also relatively constant between 3000 and 2400 wavenumbers at a value of 0.29. Between 2200 and 500 wavenumbers, the spectral emittance of deposits from the sub-bituminous coal increases from approximately 0.29 to 0.55. Differences between these spectral emittance measurements and those measured ex situ illustrate the importance of making in situ measurements. Band emittances were calculated using the measured spectral emittances, and band emittances of the deposits are reported as functions of temperature.

  14. Simulation of emittance growth in the ALS [Advanced Light Source] pre-injector

    International Nuclear Information System (INIS)

    Transverse and longitudinal beam dynamics in the ALS preinjector were simulated with a 2 1/2 D code. Strong space charge-forces at low energy and nonlinearities caused emittances to grow. However, careful tuning of the bunching system and the linac reduced emittance growth to an acceptable label. About 1/3 of the gun output are within the required energy spread and the normalized rms emittance is significantly lower than the expected value. 3 refs., 7 figs., 1 tab

  15. Sparsity-based AOA Estimation for Emitter Localization

    Directory of Open Access Journals (Sweden)

    Lingwen Zhang

    2012-08-01

    Full Text Available Angle of arrival (AOA is able to achieve high accuracy when the antenna arrays are deployed much closer to the emitter. However, spatial resolution problem still exists. This paper presents a novel AOA estimation method called sparsity angle sensing (SAS to improve the resolution. It integrates compressive sensing theorem into the parameter estimation formula. Traditional approaches for AOA estimation such as beamforming (BF, minimum variance distortionless response (MVDR, multiple signal classification (MUSIC are compared with SAS, and simulation results are discussed. It is shown that SAS method outperforms the other three methods in spatial resolution and robustness.  

  16. Applications using high-Tc superconducting terahertz emitters

    Science.gov (United States)

    Nakade, Kurama; Kashiwagi, Takanari; Saiwai, Yoshihiko; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

    2016-01-01

    Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system. The third is a system with precise temperature control to measure the liquid absorption coefficient. The detailed characteristics of these systems are discussed. PMID:26983905

  17. Coupling of Quantum Emitters in Nanodiamonds to Plasmonic Structures

    OpenAIRE

    Kumar, Shailesh,; Andersen, Ulrik Lund

    2012-01-01

    Denne PhD-afhandling beskriver arbejdet med forstærkning og effektiv kanalisering af fotoner emitteret fra en enkelt-foton-kilde. Den anvendte emitter, nitrogen-vakance (NV) centeret, er et defektcenter i diamant. NV-centret har mange unikke egenskaber såsom lang kohærenstid af dets elektron-spin-tilstande og muligheden for optisk at aflæse dets spintilstand, hvilket gør det nyttigt til kvanteberegningsanvendelser. Effektiv kanalisering i kombination med forstærkning af emission fra NV-center...

  18. Applications using high-Tc superconducting terahertz emitters

    Science.gov (United States)

    Nakade, Kurama; Kashiwagi, Takanari; Saiwai, Yoshihiko; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

    2016-03-01

    Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system. The third is a system with precise temperature control to measure the liquid absorption coefficient. The detailed characteristics of these systems are discussed.

  19. Feasibility of a ring FEL at low emittance storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Agapov, I., E-mail: ilya.agapov@xfel.eu

    2015-09-01

    A scheme for generating coherent radiation at latest generation low emittance storage rings such as PETRA III at DESY (Balewski et al., 2004 [1]) is proposed. The scheme is based on focusing and subsequent defocusing of the electron beam in the longitudinal phase space at the undulator location. The expected performance characteristics are estimated for radiation in the wavelength range of 500–1500 eV. It is shown that the average brightness is increased by several orders of magnitude compared to spontaneous undulator radiation, which can open new perspectives for photon-hungry soft X-ray spectroscopy techniques.

  20. Strong-field photoemission from silicon field emitter arrays

    Energy Technology Data Exchange (ETDEWEB)

    Keathley, Phillip D.; Putnam, William P. [Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA (United States); Sell, Alexander; Kaertner, Franz X. [Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA (United States); Center for Free-Electron Laser Science, DESY, Hamburg (Germany); Dept. of Physics, Hamburg Univ. (Germany); Guerrera, Stephen; Velasquez-Garcia, Luis [Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2013-02-15

    Strong-field photoemission from silicon field emitter arrays is investigated experimentally and results are explained using a ''simple-man'' optical-field emission model. Spectra are collected throughout an in-situ laser annealing process, leading to a red-shift in emitted electron energy along with an increase in electron yield. After the annealing process, a high energy plateau is formed which is explained through optical-field emission along with electron re-scattering with the tip surface. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Scanning emitter lifetime imaging microscopy for spontaneous emission control

    CERN Document Server

    Frimmer, Martin; Koenderink, A Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nano-photonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while measuring its lifetime. We demonstrate the method by imaging the enhancement of the local density of optical states around metal nanowires. By nano-positioning, the decay rate of a pointlike source of fluorescence can be reversibly and repeatedly changed by a factor of two by coupling it to the guided plasmonic mode of the wire.

  2. HgMn Stars as apparent X-ray emitters

    OpenAIRE

    Hubrig, S.; Berghoefer, W.; Mathys, G.

    1998-01-01

    In the ROSAT all-sky survey 11 HgMn stars were detected as soft X-ray emitters (Berghoefer, Schmitt & Cassinelli 1996). Prior to ROSAT, X-ray observations with the Einstein Observatory had suggested that stars in the spectral range B5-A7 are devoid of X-ray emission. Since there is no X-ray emitting mechanism available for these stars (also not for HgMn stars), the usual argument in the case of an X-ray detected star of this spectral type is the existence of an unseen low-mass companion which...

  3. Carbon Nanotube Electron Emitter for X-ray Imaging

    OpenAIRE

    Jung Su Kang; Je Hwang Ryu; Kyu Chang Park

    2012-01-01

    The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP) process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube em...

  4. Critical Care

    Science.gov (United States)

    Critical care helps people with life-threatening injuries and illnesses. It might treat problems such as complications from surgery, ... attention by a team of specially-trained health care providers. Critical care usually takes place in an ...

  5. A Search for z>6.5 Lyman-alpha Emitting Galaxies with WISP

    Science.gov (United States)

    Bagley, Micaela B.; Scarlata, Claudia; Dai, Yu Sophia; Rafelski, Marc; Baronchelli, Ivano; Colbert, James W.; Dominguez, Alberto; Hathi, Nimish P.; Henry, Alaina L.; Malkan, Matthew Arnold; Martin, Crystal L.; Mehta, Vihang; Pahl, Anthony; Ross, Nathaniel; Rutkowski, Michael J.; Teplitz, Harry I.; WISP Team

    2016-01-01

    The observed number density of Lyman-alpha emitting galaxies at z>6 provides an important probe of the reionization history of the universe. Because Lyman-alpha photons are very sensitive to the presence of neutral hydrogen, the evolution of the galaxy number density above redshift 6 can be used as a measurement on the progress of reionization. However, the Lyman-alpha luminosity function is currently poorly constrained at high-z. We present the results of a systematic search for Lyman-alpha emitters (LAEs) at redshifts of ~6.5 to 7.5 using the HST WFC3 Infrared Spectroscopic Parallels (WISP) survey. WISP's uncorrelated fields are well-suited to the study of bright LAEs, minimizing the effects of clustering introduced by a patchy reionization. From the 30 deepest WISP fields, we compile a sample of single-line emitters, confirm redshifts with broadband colors, and identify LAE candidates that have "dropped out" (are undetected at the 1 sigma level) of the WFC3 UVIS filters. By combining our results with other z~7 studies, we determine whether the number density of LAEs evolves past z~6.5.

  6. Large-scale clustering of Lyman-alpha emission intensity from SDSS/BOSS

    CERN Document Server

    Croft, Rupert A C; Zheng, Zheng; Bolton, Adam; Dawson, Kyle S; Peterson, Jeffrey B; York, Donald G; Eisenstein, Daniel; Brinkmann, Jon; Brownstein, Joel; Delubac, Timothée; Font-Ribera, Andreu; Hamilton, Jean-Christophe; Lee, Khee-Gan; Myers, Adam; Palanque-Delabrouille, Nathalie; Pâris, Isabelle; Petitjean, Patrick; Pieri, Matthew M; Ross, Nicholas P; Rossi, Graziano; Schlegel, David J; Schneider, Donald P; Slosar, Anže; Vazquez, José; Viel, Matteo; Weinberg, David H; Yèche, Christophe

    2015-01-01

    (Abridged) We detect the large-scale structure of Lya emission in the Universe at redshifts z=2-3.5 by measuring the cross-correlation of Lya surface brightness with quasars in SDSS/BOSS. We use a million spectra targeting Luminous Red Galaxies at z, the amplitude of mass fluctuations, and the quasar and Lya emission bias factors. Using known values, we infer (b_alpha/3) = (3.9 +/- 0.9) x 10^-21 erg/s cm^-2 A^-1 arcsec^-2, where b_alpha is the Lya emission bias factor. If the dominant sources of Lya emission are star forming galaxies, we infer rho_SFR = (0.28 +/- 0.07) (3/b_alpha) /yr/Mpc^3 at z=2-3.5. For b_alpha=3, this value is a factor of 21-35 above previous estimates from individually detected Lya emitters, although consistent with the total rho_SFR derived from dust-corrected, continuum UV surveys. 97% of the Lya emission in the Universe at these redshifts is therefore undetected in previous surveys of Lya emitters. Our measurement is much greater than seen from stacking analyses of faint halos surroun...

  7. Numerical growth of emittance in simulations of laser-wakefield acceleration

    International Nuclear Information System (INIS)

    Transverse emittance is a crucial feature of laser-wakefield accelerators, yet accurately reproducing its value in numerical simulations remains challenging. It is shown here that, when the charge of the bunch exceeds a few tens of pico-coulombs, particle-in-cell (PIC) simulations erroneously overestimate the emittance. This is mostly due the interaction of spurious Cherenkov radiation with the bunch, which leads to a steady growth of emittance during the simulation. A new computational scheme is proposed, which is free of spurious Cherenkov radiation. It can be easily implemented in existing PIC codes and leads to a substantial reduction of the emittance growth. (authors)

  8. Beam emittance investigation in high brightness injector using different driver laser profiles

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Beam emittance plays an important role in any accelerator, and it is a main parameter to judge the performance of an accelerator. Emittance optimization is an indispensable part in conditioning and operation of the facility. For a laser-driven high brightness injector, different time structure of the laser pulse has different effects on transverse emittance. In order to compare Gaussian and flat-top laser pulse, systematic simulations of 500 pC have been done. From the simulation results, one can see that flat-top pulse laser will yield smaller minimal transverse beam size and transverse beam emittance than Gaussian pulse laser.

  9. Biofilm structure and its influence on clogging in drip irrigation emitters distributing reclaimed wastewater

    Institute of Scientific and Technical Information of China (English)

    YAN Dazhuang; BAI Zhihui; Mike Rowan; GU Likun; Ren Shumei; YANG Peiling

    2009-01-01

    Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy (SEM) revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides (EPS) and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide and phospholipid fatty acids (PLFAs) showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coefficient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path (Emitter C) had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.

  10. Tunable graphene micro-emitters with fast temporal response and controllable electron emission.

    Science.gov (United States)

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-05-10

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications.

  11. Copper conducting electrode with nickel as a seed layer for selective emitter crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Atteq ur; Shin, Eun Gu; Lee, Soo Hong [Sejong University, Seoul (Korea, Republic of)

    2014-09-15

    In this research, we investigated selective emitter formation with a single-step photolithography process having a metallization scheme composed of nickel/copper metal stacks. The nickel seed layers were deposited by applying the electroless deposition process while copper was formed by light induced electro-plating arrangements as the main conducting electrode. The electroless deposition of nickel, along with a sintering process, was employed to create a diffusion barrier between copper and silicon. The nickel metal stack below the copper-conducting electrode also helped in lowering the sheet resistance and improving the contact adhesion. The nickel used as a seed layer was successfully demonstrated in the fabrication of a homogeneous 60 Ω/ emitter and selective emitter cells. Lower series resistances of 0.165 Ω and 0.253 Ω were achieved for the selective emitter and the homogeneous emitter cells, respectively. The best cell efficiency of 18.37% for the selective emitter solar cell was achieved, with average cell efficiencies of 18.17% and 17.3% for the selective emitter and the homogeneous emitter cells, respectively. An approximate efficiency increase of about 0.8% was recorded for the selective emitter solar cells.

  12. Analysis of emittance compensation and simulation results to photo-cathode RF gun

    CERN Document Server

    LiuShengGuang

    2002-01-01

    The emittance compensation technology will be used on the photo-cathode RF gun for Shanghai SDUV-FEL. The space charge force and its effect on electron beam transverse emittance in RF gun is studied, the principle of emittance compensation in phase-space is discussed. The authors have designed a compensation solenoid and calculated its magnetic field distribution. Its performance has been studied by the code PARMELA. A simulation result indicates that the normalized transverse RMS emittance for electron beam of 1.5 nC is 1.612 pi mm centre dot mrad, electron energy E = 5.71 MeV

  13. Elementary framework for cold field emission from quantum-confined, non-planar emitters

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, A. A., E-mail: apatters@mit.edu; Akinwande, A. I. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA and Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-05-07

    For suitably small field emitters, the effects of quantum confinement at the emitter tip may have a significant impact on the emitter performance and total emitted current density (ECD). Since the geometry of a quantum system uniquely determines the magnitude and distribution of its energy levels, a framework for deriving ECD equations from cold field electron emitters of arbitrary geometry and dimensionality is developed. In the interest of obtaining semi-analytical ECD equations, the framework is recast in terms of plane wave solutions to the Schrödinger equation via the use of the Jeffreys-Wentzel-Kramers-Brillouin approximation. To demonstrate the framework's consistency with our previous work and its capabilities in treating emitters with non-planar geometries, ECD equations were derived for the normally unconfined cylindrical nanowire (CNW) and normally confined (NC) CNW emitter geometries. As a function of the emitter radius, the NC CNW emitter ECD profile displayed a strong dependence on the Fermi energy and had an average ECD that exceeded the Fowler-Nordheim equation for typical values of the Fermi energy due to closely spaced, singly degenerate energy levels (excluding electron spin), comparatively large electron supply values, and the lack of a transverse, zero-point energy. Such characteristics suggest that emitters with non-planar geometries may be ideal for emission from both an electron supply and electrostatics perspective.

  14. High Turndown Ratio, High Delta-Emittance, Variable Emissivity Electrochromics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Among thermal control methods, variable-emittance materials remain the most promising for addressing deficiencies of current systems (mechanical louvers, loop heat...

  15. Tunable graphene micro-emitters with fast temporal response and controllable electron emission

    Science.gov (United States)

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-05-01

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications.

  16. A method to measure the nonlinear force caused emittance growth in a RF photoinjector

    Institute of Scientific and Technical Information of China (English)

    Li Zheng-Hong; Yang Zhen-Ping

    2006-01-01

    Based on the multi-slit method, a new method is introduced to measure the non linear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.

  17. ALPHA MIS: Reference manual

    Energy Technology Data Exchange (ETDEWEB)

    Lovin, J.K.; Haese, R.L.; Heatherly, R.D.; Hughes, S.E.; Ishee, J.S.; Pratt, S.M.; Smith, D.W.

    1992-02-01

    ALPHA is a powerful and versatile management information system (MIS) initiated and sponsored and by the Finance and Business Management Division of Oak Ridge National Laboratory, who maintain and develop it in concert with the Business Systems Division for its Information Center. A general-purpose MIS, ALPHA allows users to access System 1022 and System 1032 databases to obtain and manage information. From a personal computer or a data terminal, Energy Systems employees can use ALPHA to control their own report reprocessing. Using four general commands (Database, Select, Sort, and Report) they can (1) choose a mainframe database, (2) define subsets within it, (3) sequentially order a subset by one or more variables, and (4) generate a report with their own or a canned format.

  18. Measurement of $\\alpha$-particle quenching in LAB based scintillator in independent small-scale experiments

    CERN Document Server

    von Krosigk, B; Hans, S; Junghans, A R; Kögler, T; Kraus, C; Kuckert, L; Liu, X; Nolte, R; O'Keeffe, H M; Tseung, H S Wan Chan; Wilson, J R; Wright, A; Yeh, M; Zuber, K

    2015-01-01

    The $\\alpha$-particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, $\\alpha$-particles were produced in the scintillator via $^{12}$C($n$,$\\alpha$)$^9$Be reactions. In the second approach, the scintillator was loaded with 2% of $^{\\mathrm{nat}}$Sm providing an $\\alpha$-emitter, $^{147}$Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water-filled SNO+ detector and the radioactive contaminants $^{222}$Rn, $^{218}$Po and $^{214}$Po provided the $\\alpha$-particle signal. The behavior of the observed $\\alpha$-particle light outputs are in agreement with each case successfully described by Birks' law. The resulting Birks parameter $kB$ ranges from $(0.0071\\pm0.0003)$ cm/MeV to $(0.0076\\pm0.0003)$ cm/MeV. In the first approach, the $\\alpha$-particle light response was measured simultaneously with the light response of recoil protons produced via neutron-proto...

  19. Final Muon Emittance Exchange in Vacuum for a Collider

    Energy Technology Data Exchange (ETDEWEB)

    Summers, Don [Univ. of Mississippi, Oxford, MS (United States); Acosta, John [Univ. of Mississippi, Oxford, MS (United States); Cremaldi, Lucien [Univ. of Mississippi, Oxford, MS (United States); Hart, Terry [Univ. of Mississippi, Oxford, MS (United States); Oliveros, Sandra [Univ. of Mississippi, Oxford, MS (United States); Perera, Lalith [Univ. of Mississippi, Oxford, MS (United States); Wu, Wanwei [Univ. of Mississippi, Oxford, MS (United States); Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-05-07

    We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low β region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 μs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.

  20. Electrically pumped single-defect light emitters in WSe2

    Science.gov (United States)

    Schwarz, S.; Kozikov, A.; Withers, F.; Maguire, J. K.; Foster, A. P.; Dufferwiel, S.; Hague, L.; Makhonin, M. N.; Wilson, L. R.; Geim, A. K.; Novoselov, K. S.; Tartakovskii, A. I.

    2016-06-01

    Recent developments in fabrication of van der Waals heterostructures enable new type of devices assembled by stacking atomically thin layers of two-dimensional materials. Using this approach, we fabricate light-emitting devices based on a monolayer WSe2, and also comprising boron nitride tunnelling barriers and graphene electrodes, and observe sharp luminescence spectra from individual defects in WSe2 under both optical and electrical excitation. This paves the way towards the realisation of electrically-pumped quantum emitters in atomically thin semiconductors. In addition we demonstrate tuning by more than 1 meV of the emission energy of the defect luminescence by applying a vertical electric field. This provides an estimate of the permanent electric dipole created by the corresponding electron-hole pair. The light-emitting devices investigated in our work can be assembled on a variety of substrates enabling a route to integration of electrically pumped single quantum emitters with existing technologies in nano-photonics and optoelectronics.