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Sample records for multi-section frisch-gridded ionization

  1. Characterization of reticulated vitreous carbon foam using a frisch-grid parallel-plate ionization chamber

    Science.gov (United States)

    Edwards, Nathaniel S.; Conley, Jerrod C.; Reichenberger, Michael A.; Nelson, Kyle A.; Tiner, Christopher N.; Hinson, Niklas J.; Ugorowski, Philip B.; Fronk, Ryan G.; McGregor, Douglas S.

    2018-06-01

    The propagation of electrons through several linear pore densities of reticulated vitreous carbon (RVC) foam was studied using a Frisch-grid parallel-plate ionization chamber pressurized to 1 psig of P-10 proportional gas. The operating voltages of the electrodes contained within the Frisch-grid parallel-plate ionization chamber were defined by measuring counting curves using a collimated 241Am alpha-particle source with and without a Frisch grid. RVC foam samples with linear pore densities of 5, 10, 20, 30, 45, 80, and 100 pores per linear inch were separately positioned between the cathode and anode. Pulse-height spectra and count rates from a collimated 241Am alpha-particle source positioned between the cathode and each RVC foam sample were measured and compared to a measurement without an RVC foam sample. The Frisch grid was positioned in between the RVC foam sample and the anode. The measured pulse-height spectra were indiscernible from background and resulted in negligible net count rates for all RVC foam samples. The Frisch grid parallel-plate ionization chamber measurement results indicate that electrons do not traverse the bulk of RVC foam and consequently do not produce a pulse.

  2. Ambiguities in the grid-inefficiency correction for Frisch-Grid Ionization Chambers

    International Nuclear Information System (INIS)

    Al-Adili, A.; Hambsch, F.-J.; Bencardino, R.; Oberstedt, S.; Pomp, S.

    2012-01-01

    Ionization chambers with Frisch grids have been very successfully applied to neutron-induced fission-fragment studies during the past 20 years. They are radiation resistant and can be easily adapted to the experimental conditions. The use of Frisch grids has the advantage to remove the angular dependency from the charge induced on the anode plate. However, due to the Grid Inefficiency (GI) in shielding the charges, the anode signal remains slightly angular dependent. The correction for the GI is, however, essential to determine the correct energy of the ionizing particles. GI corrections can amount to a few percent of the anode signal. Presently, two contradicting correction methods are considered in literature. The first method adding the angular-dependent part of the signal to the signal pulse height; the second method subtracting the former from the latter. Both additive and subtractive approaches were investigated in an experiment where a Twin Frisch-Grid Ionization Chamber (TFGIC) was employed to detect the spontaneous fission fragments (FF) emitted by a 252 Cf source. Two parallel-wire grids with different wire spacing (1 and 2 mm, respectively), were used individually, in the same chamber side. All the other experimental conditions were unchanged. The 2 mm grid featured more than double the GI of the 1 mm grid. The induced charge on the anode in both measurements was compared, before and after GI correction. Before GI correction, the 2 mm grid resulted in a lower pulse-height distribution than the 1 mm grid. After applying both GI corrections to both measurements only the additive approach led to consistent grid independent pulse-height distributions. The application of the subtractive correction on the contrary led to inconsistent, grid-dependent results. It is also shown that the impact of either of the correction methods is small on the FF mass distributions of 235 U(n th , f).

  3. A method for measuring the electron drift velocity in working gas using a Frisch-grid ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Chen, Jinxiang; Zhang, Guohui, E-mail: guohuizhang@pku.edu.cn

    2016-12-21

    A method for measuring the electron drift velocity in working gas is proposed. Based on the cathode and the anode signal waveforms of the Frisch-grid ionization chamber, the electron drift velocity is extracted. With this method, the electron drift velocities in Ar + 10% CH{sub 4}, Ar + 3.5% CO{sub 2} and Kr + 2.7% CO{sub 2} gases have been measured and the results are compared with the existing measurements and the simulating results. Using this method, the electron drift velocity can be monitored throughout the experiment of charged particle without bothering the measurement of other parameters, such as the energy and orientation.

  4. A twin Frisch-grid ionization chamber as a selective detector for the delayed gamma-spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Gaudefroy, L., E-mail: laurent.gaudefroy@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Roger, T., E-mail: roger@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Pancin, J., E-mail: pancin@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Spitaels, C. [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Aupiais, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Mottier, J. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS-IN2P3, F-91406 Orsay (France)

    2017-05-21

    We present a twin Frisch-grid ionization chamber. The detector is meant to provide high selective power for the study of delayed gamma-ray spectroscopy of fission fragments produced via {sup 252}Cf spontaneous fission. A mean energy resolution on the kinetic energy of fission fragments of 675 keV (FWHM) is achieved and allows us to resolve masses of fragments for fission events where neutron emission is not energetically possible. The mean mass resolution measured for these particular events amounts to 0.54 mass units (FWHM). For fission events with neutron emission a resolution of 4 mass units (FWHM) is reported. Information on fragment emission angle is measured with a resolution of 0.1 on the difference of the cosines determined for both halves of the detector. A charge resolution of 4.5 charge units (FWHM) is also demonstrated.

  5. Geometrically weighted semiconductor Frisch grid radiation spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, D.S. [Dept. of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109-2104 (United States); Rojeski, R.A. [Etec Systems, Inc., 26460 Corporate Ave., Hayward, CA 94545 (United States); He, Z. [Dept. of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109-2104 (United States); Wehe, D.K. [Dept. of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109-2104 (United States); Driver, M. [eV Products, 375 Saxonburg Blvd., Saxonburg, PA 16056 (United States); Blakely, M. [eV Products, 375 Saxonburg Blvd., Saxonburg, PA 16056 (United States)

    1999-02-11

    A new detector geometry is described with relatively high gamma ray energy resolution at room temperature. The device uses the geometric weighting effect, the small pixel effect and the Frisch grid effect to produce high gamma ray energy resolution. The design is simple and easy to construct. The device performs as a gamma ray spectrometer without the need for pulse shape rejection or correction, and it requires only one signal output to any commercially available charge sensitive preamplifier. The device operates very well with conventional NIM electronic systems. Presently, room temperature (23 deg. C) energy resolutions of 2.68% FWHM at 662 keV and 2.45% FWHM at 1.332 MeV have been measured with a 1 cm{sup 3} prism shaped CdZnTe device.

  6. CZT Virtual Frisch-grid Detector: Principles and Applications

    International Nuclear Information System (INIS)

    Cui, Y.; Bolotnikov, A.; Camarda, G.; Hossain, A.; James, R.B.

    2009-01-01

    Cadmium Zinc Telluride (CdZnTe or CZT) is a very attractive material for using as room-temperature semiconductor detectors, because it has a wide bandgap and a high atomic number. However, due to the material's poor hole mobility, several special techniques were developed to ensure its suitability for radiation detection. Among them, the virtual Frisch-grid CZT detector is an attractive option, having a simple configuration, yet delivering an outstanding spectral performance. The goal of our group in Brookhaven National Laboratory (BNL) is to improve the performance of Frisch-ring CZT detectors; most recently, that effort focused on the non-contacting Frisch-ring detector, allowing us to build an inexpensive, large-volume detector array with high energy-resolution and a large effective area. In this paper, the principles of virtual Frisch-grid detectors are described, especially BNL's innovative improvements. The potential applications of virtual Frisch-grid detectors are discussed, and as an example, a hand-held gamma-ray spectrometer using a CZT virtual Frischgrid detector array is introduced, which is a self-contained device with a radiation detector, readout circuit, communication circuit, and high-voltage supply. It has good energy resolution of 1.4% (FWHM of 662-keV peak) with a total detection volume of ∼20 cm 3 . Such a portable inexpensive device can be used widely in nonproliferation applications, non-destructive detection, radiation imaging, and for homeland security. Extended systems based on the same technology have potential applications in industrial- and nuclear-medical-imaging

  7. Enhanced R200 with Frisch-Grid CZT

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-12-01

    The goal of this project is to demonstrate an engineering prototype of a gamma ray spectrometer that uses Cadmium Zinc Telluride (CZT) in a configuration comprised of an array of position-sensitive virtual Frisch grid (PSVFG) detectors and show its capability to perform functions that would be useful to the IAEA. The detectors should achieve energy resolution of ~2% at 200 keV and <1% at > 662 keV, thereby outperforming all hand-held instruments currently in use other than cryogenically cooled germanium. BNL will make every effort to transfer the technology to an industrial partner so that robust, fieldable instruments can be manufactured.

  8. Simulation of the anode structure for capacitive frisch grid CdZnTe detectors

    International Nuclear Information System (INIS)

    Min Jiahua; Shi Zhubin; Sang Wenbin; Zhao Hengyu; Teng Jianyong; Qian Yongbiao; Liu Jishan

    2009-01-01

    CdZnTe (CZT) capacitive Frisch grid detectors can achieve a higher detecting resolution. The anode structrure might have an important role in improving the weighting potential distribution of the detectors. In this paper, four anode structures of capacitive Frisch grid structures have been analyzed with FE simulation, based on a 3-dimensional weighting potential analysis. The weighting potential distributions in modified anode devices (Model B, C and D) are optimized compared with a square device (Model A). In model C and D, the abrupt weighting potential can be well modified. However, with increased radius of the circular electrode in Model C the weighting potential platform away from the anode becomes higher and higher and in Model D, the weighting potential does not vary too much. (authors)

  9. Basic study on the development of low exposure CT with Frisch grid avalanche diode. JAERI's nuclear research promotion program, H13-011 (Contract research)

    International Nuclear Information System (INIS)

    Katagiri, Masaki; Onabe, Hideaki

    2005-03-01

    For the development of low exposure CT, we have conducted a basic study on Frisch grid avalanche diode detector to realize a high efficiency, high counting rate X-ray detector. First, we fabricated Frisch grid Si detector made of one crystal and studied their features. For the development of X-ray detector with higher performance, bonding semiconductor wafers, including different semiconductors, such as Si and CdTe, is necessary. We have bonded Si wafers by surface activation method and studied on the electric performance of bonded Si wafers. The current-voltage curve of bonded pn Si wafers showed rectifying characteristics, although Si pn junctions are made by diffusion method, generally. Second, we proposed a low dose exposure X-ray transmission method using filtered X-ray and energy subtraction method. The dose exposure with this method is estimated as low as 30% of that of using white X-rays. If we compare the dose exposure of conventional current measurement method, we would conclude further advantage of this method. With the combination of low dose exposure X-ray transmission method and the Frisch grid detector, high performance X-ray transmission method and low exposure CT system will be developed in future. (author)

  10. Experiences with large-area frisch grid chambers in low-level alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hoetzl, H.; Winkler, R. (Gesellschaft fuer Strahlen- und Umweltforschung m.b.H. Muenchen, Neuherberg (Germany, F.R.). Inst. fuer Strahlenschutz)

    1984-06-15

    The properties of parallel-plate gridded ionization chambers with areas of 300 cm/sup 2/, developed by us for alpha spectrometry of samples with low specific alpha activity are reported. Several practical hints for optimum operating conditions are presented. The chambers can be operated routinely at atmospheric pressure for several days, without the need for purification of the gas filling (P10). The minimum detectable activity at 5 MeV is 0.01 pCi, based on 4.65 standard deviations of background and 1000 min counting time. At the GSF Research Center ionization chambers of this type are used for the analysis of natural alpha emitters, as well as of transuranium nuclides in environmental samples by: a) direct alpha spectrometry without any previous treatment of the sample, b) semi-direct spectrometry after removal of organic matter by low-temperature ashing and c) spectrometry after chemical separation. Some typical example of application are given. Furthermore the range of application of the chambers in comparison to semiconductor detectors in the field of low-level alpha spectrometry is discussed.

  11. Experiences with large-area frisch grid chambers in low-level alpha spectrometry

    International Nuclear Information System (INIS)

    Hoetzl, H.; Winkler, R.

    1984-01-01

    The properties of parallel-plate gridded ionization chambers with areas of 300 cm 2 , developed by us for alpha spectrometry of samples with low specific alpha activity are reported. Several practical hints for optimum operating conditions are presented. The chambers can be operated routinely at atmospheric pressure for several days, without the need for purification of the gas filling (P10). The minimum detectable activity at 5 MeV is 0.01 pCi, based on 4.65 standard deviations of background and 1000 min counting time. At the GSF Research Center ionization chambers of this type are used for the analysis of natural alpha emitters, as well as of transuranium nuclides in environmental samples by: a) direct alpha spectrometry without any previous treatment of the sample, b) semi-direct spectrometry after removal of organic matter by low-temperature ashing and c) spectrometry after chemical separation. Some typical example of application are given. Furthermore the range of application of the chambers in comparison to semiconductor detectors in the field of low-level alpha spectrometry is discussed. (orig.)

  12. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, A. E., E-mail: bolotnik@bnl.gov; Ackley, K.; Camarda, G. S.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hossain, A.; Mahler, G.; Maritato, M.; Roy, U.; Salwen, C.; Vernon, E.; Yang, G.; James, R. B. [Brookhaven National Laboratory, Upton, New York 11793 (United States); Hodges, D. [University of Texas at El Paso, El Paso, Texas 79968 (United States); Lee, W. [Korea University, Seoul 136-855 (Korea, Republic of); Petryk, M. [SUNY Binghamton, Vestal, New York 13902 (United States)

    2015-07-15

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe detectors coupled to a front-end readout application-specific integrated circuit (ASIC) for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6 × 6 × 15 mm{sup 3} detectors grouped into 3 × 3 sub-arrays of 2 × 2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays’ performance and reduction of their cost are possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

  13. Making MUSIC: A multiple sampling ionization chamber

    International Nuclear Information System (INIS)

    Shumard, B.; Henderson, D.J.; Rehm, K.E.; Tang, X.D.

    2007-01-01

    A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the (α, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for (α, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only (α, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. x 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the (α, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the (α, p) reaction to reach the anode segment below the reaction

  14. Making MUSIC: A multiple sampling ionization chamber

    Science.gov (United States)

    Shumard, B.; Henderson, D. J.; Rehm, K. E.; Tang, X. D.

    2007-08-01

    A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the (α, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for (α, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only (α, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. × 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the (α, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the (α, p) reaction to reach the anode segment below the reaction.

  15. Making MUSIC: A multiple sampling ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Shumard, B. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States)]. E-mail: shumard@phy.anl.gov; Henderson, D.J. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States); Rehm, K.E. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States); Tang, X.D. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States)

    2007-08-15

    A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the ({alpha}, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for ({alpha}, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only ({alpha}, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. x 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the ({alpha}, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the ({alpha}, p) reaction to reach the anode segment below the reaction.

  16. High resolution multiple sampling ionization chamber (MUSIC) sensitive to position coordinates

    International Nuclear Information System (INIS)

    Petrascu, H.; Kumagai, H.; Tanihata, I.; Petrascu, M.

    1999-01-01

    A new type of MUSIC sensitive to position coordinates is reported. The development of the first version of this type of chamber is based on the principles presented by Badhwar in 1973. The present detector will be used in experiments on fusion by using radioactive beams. This chamber due to the high resolution is suitable to identification and tracking of low Z particles. One of our goals, when we started this work, was to reduce as much as possible the Z value of particles that can be 'seen' by an ionization chamber. The resolution of the chamber was significantly improved by connecting the preamplifiers directly to the MUSIC's pads. These preamplifiers are able to work in vacuum and very low gas pressure. In this way the value of signal to noise ratio was increased by a factor of ∼10. The detector is of Frisch grid type, with the anode split into 10 active pads. It is the first model of a MUSIC with the field shared between the position grid and the anode pads. The Frisch grid was necessary because the detector is originally designed for very accurate energy measurements and particle identification. A drawing of this detector is shown. The detector itself consists of four main parts. The first one is the constant field-gradient cage, sandwiched in between the cathode and the Frisch grid. The second is the Frisch grid. The third is the position grid located under the Frisch grid. The last one is the plate with the anode pads. The cage is made of 100 μm Cu-Be wires. Every wire was tensioned with a weight representing half of its breaking limit. The Frisch grid was done on an aluminium frame, on which 20 μm W wires spaced 0.3 mm, were wound. For the position grid, 10 groups of 20 μm gold plated W wires have been used. Each group consisted of 5 wires spaced 0.9 mm and connected in parallel. The anode pads 7.8 x 60 mm 2 were perpendicular to the beam direction. Each pad and each of the position wire groups were connected to a preamplifier. The energy resolution

  17. Characterization of an Ionization Readout Tile for nEXO

    Science.gov (United States)

    Jewell, M.; Schubert, A.; Cen, W. R.; Dalmasson, J.; DeVoe, R.; Fabris, L.; Gratta, G.; Jamil, A.; Li, G.; Odian, A.; Patel, M.; Pocar, A.; Qiu, D.; Wang, Q.; Wen, L. J.; Albert, J. B.; Anton, G.; Arnquist, I. J.; Badhrees, I.; Barbeau, P.; Beck, D.; Belov, V.; Bourque, F.; Brodsky, J. P.; Brown, E.; Brunner, T.; Burenkov, A.; Cao, G. F.; Cao, L.; Chambers, C.; Charlebois, S. A.; Chiu, M.; Cleveland, B.; Coon, M.; Craycraft, A.; Cree, W.; Côté, M.; Daniels, T.; Daugherty, S. J.; Daughhetee, J.; Delaquis, S.; Der Mesrobian-Kabakian, A.; Didberidze, T.; Dilling, J.; Ding, Y. Y.; Dolinski, M. J.; Dragone, A.; Fairbank, W.; Farine, J.; Feyzbakhsh, S.; Fontaine, R.; Fudenberg, D.; Giacomini, G.; Gornea, R.; Hansen, E. V.; Harris, D.; Hasan, M.; Heffner, M.; Hoppe, E. W.; House, A.; Hufschmidt, P.; Hughes, M.; Hößl, J.; Ito, Y.; Iverson, A.; Jiang, X. S.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Lan, Y.; Leonard, D. S.; Li, S.; Li, Z.; Licciardi, C.; Lin, Y. H.; MacLellan, R.; Michel, T.; Mong, B.; Moore, D.; Murray, K.; Newby, R. J.; Ning, Z.; Njoya, O.; Nolet, F.; Odgers, K.; Oriunno, M.; Orrell, J. L.; Ostrovskiy, I.; Overman, C. T.; Ortega, G. S.; Parent, S.; Piepke, A.; Pratte, J.-F.; Radeka, V.; Raguzin, E.; Rao, T.; Rescia, S.; Retiere, F.; Robinson, A.; Rossignol, T.; Rowson, P. C.; Roy, N.; Saldanha, R.; Sangiorgio, S.; Schmidt, S.; Schneider, J.; Sinclair, D.; Skarpaas, K.; Soma, A. K.; St-Hilaire, G.; Stekhanov, V.; Stiegler, T.; Sun, X. L.; Tarka, M.; Todd, J.; Tolba, T.; Tsang, R.; Tsang, T.; Vachon, F.; Veeraraghavan, V.; Visser, G.; Vuilleumier, J.-L.; Wagenpfeil, M.; Weber, M.; Wei, W.; Wichoski, U.; Wrede, G.; Wu, S. X.; Wu, W. H.; Yang, L.; Yen, Y.-R.; Zeldovich, O.; Zhang, X.; Zhao, J.; Zhou, Y.; Ziegler, T.

    2018-01-01

    A new design for the anode of a time projection chamber, consisting of a charge-detecting "tile", is investigated for use in large scale liquid xenon detectors. The tile is produced by depositing 60 orthogonal metal charge-collecting strips, 3 mm wide, on a 10 cm × 10 cm fused-silica wafer. These charge tiles may be employed by large detectors, such as the proposed tonne-scale nEXO experiment to search for neutrinoless double-beta decay. Modular by design, an array of tiles can cover a sizable area. The width of each strip is small compared to the size of the tile, so a Frisch grid is not required. A grid-less, tiled anode design is beneficial for an experiment such as nEXO, where a wire tensioning support structure and Frisch grid might contribute radioactive backgrounds and would have to be designed to accommodate cycling to cryogenic temperatures. The segmented anode also reduces some degeneracies in signal reconstruction that arise in large-area crossed-wire time projection chambers. A prototype tile was tested in a cell containing liquid xenon. Very good agreement is achieved between the measured ionization spectrum of a 207Bi source and simulations that include the microphysics of recombination in xenon and a detailed modeling of the electrostatic field of the detector. An energy resolution σ/E=5.5% is observed at 570 keV, comparable to the best intrinsic ionization-only resolution reported in literature for liquid xenon at 936 V/cm.

  18. The mass dependence of the signal peak height of a Bragg-curve ionization chamber

    International Nuclear Information System (INIS)

    Shenhav, N.J.; Stelzer, H.

    1985-01-01

    The Bragg-curve detector of the parallel plate ionization chamber type generates a signal that is a distorted replica of the original Bragg-curve. In result of this distortion, the signal peak height is not only a function of the atomic number of the heavy ion, as it is often stated, but also of the particle mass. This mass effect was studied with the aid of computer simulation, and it was found to be dependent on the Frisch grid to anode gap width and on the detector gas. The charge resolution of the detector is affected very significantly by this mass dependence of the signal peak height. Therefore, a careful selection of the detector gas and the grid to anode gap width is necessary, if good charge resolution over a wide range of heavy ions is required. (orig.)

  19. Ionization

    International Nuclear Information System (INIS)

    2002-01-01

    This document reprints the text of the French by-law from January 8, 2002 relative to the approval and to the controls and verifications of facilities devoted to the ionizing of food products for human beings and animals. The by-law imposes the operators of such facilities to perform measurements and dosimetric verifications all along the ionization process. (J.S.)

  20. Enhancing the Teaching of Introductory Economics with a Team-Based, Multi-Section Competition

    Science.gov (United States)

    Beaudin, Laura; Berdiev, Aziz N.; Kaminaga, Allison Shwachman; Mirmirani, Sam; Tebaldi, Edinaldo

    2017-01-01

    The authors describe a unique approach to enhancing student learning at the introductory economics level that utilizes a multi-section, team-based competition. The competition is structured to supplement learning throughout the entire introductory course. Student teams are presented with current economic issues, trends, or events, and use economic…

  1. Prevalence of ligamentum arteriosum calcification on multi-section spiral CT and digital radiography.

    Science.gov (United States)

    Hong, Gil-Sun; Goo, Hyun Woo; Song, Jae-Woo

    2012-06-01

    To investigate the prevalence of ligamentum arteriosum calcification (LAC) on multi-section spiral CT and digital radiography. Five hundred and eight children and 232 adults who performed multi-section chest CT were included in this study and were divided into nine age groups: A (0-5 years), B (6-10 years), C (11-15 years), D (16-20 years), E (21-30 years), F (31-40 years), G (41-50 years), H (51-60 years), and I (61-70 years). Two radiologists assessed the presence of LAC on axial and coronal CT images, defined as focal calcific density on both or on one plane with attenuation >100 Hounsfield unit. The prevalence of LAC on CT was compared between children and adults, and between unenhanced and enhanced CT in children. The prevalence of LAC on digital radiography was evaluated in 476 children. The prevalence of definite LAC on unenhanced multi-section CT was significantly higher in children (37.8 %) than in adults (11.2 %) (P CT were 4.5, 12.8, 8.1, 19.0, 0.0, 0.0, 0.0, 2.0, and 1.9 %. In children, the prevalence of LAC was significantly higher on unenhanced than on enhanced CT (37.8 vs. 16.4 %, P children. LAC is frequently observed in children and adults on multi-section spiral CT, more frequently than previously reported. Compared with that on multi-section spiral CT, the prevalence of LAC on digital radiography is substantially low.

  2. A 0.8–8 GHz Multi-Section Coupled Line Balun

    Directory of Open Access Journals (Sweden)

    Srikanth Itapu

    2015-04-01

    Full Text Available In this work, we propose a wideband multi-section transforming coupled-line balun using near equal length transmission line elements. The resulting design is realized by cascading several coupled-lines with minimal discontinuities. The multi-section Chebyshev matching optimizes bandwidth at the expense of passband ripple. The proposed design delivers good impedance matching and consistent 180° phase shift over 0.8–8 GHz frequency spectrum. Furthermore, the need for vias in conventional balun designs is relaxed by replacing the short-circuited (SC terminal by its equivalent dual open-circuited (OC element. The proposed design is simulated, fabricated, and measured. Both simulated and measured results are in a good agreement, and show an input port matching of below −9.7 dB over the design bandwidth, with a maximum phase and amplitude imbalance of 2.1° and 0.9 dB, respectively.

  3. Design and Analysis of a Bio-Inspired Wire-Driven Multi-Section Flexible Robot

    OpenAIRE

    Li, Zheng; Du, Ruxu

    2013-01-01

    This paper presents a bio-inspired wire-driven multi-section flexible robot. It is inspired by the snake skeleton and octopus arm muscle arrangements. The robot consists of three sections and each section is made up of several identical vertebras, which are articulated by both spherical joints and a flexible backbone. Each section is driven by two groups of wires, controlling the bending motion in X and Y directions. This design integrates the serpentine robots' structure and the continuum ro...

  4. Mordell-Weil torsion in the mirror of multi-sections

    Energy Technology Data Exchange (ETDEWEB)

    Oehlmann, Paul-Konstantin [Physics Department, Virginia Tech, Robeson Hall 0435, 850 West Campus Drive, Blacksburg, VA, 24061 (United States); Bethe Center for Theoretical Physics, Physikalisches Institut der Universität Bonn,Nussallee 12, Bonn, 53115 (Germany); Reuter, Jonas; Schimannek, Thorsten [Bethe Center for Theoretical Physics, Physikalisches Institut der Universität Bonn,Nussallee 12, Bonn, 53115 (Germany)

    2016-12-12

    We give further evidence that genus-one fibers with multi-sections are mirror dual to fibers with Mordell-Weil torsion. In the physics of F-theory compactifications this implies a relation between models with a non-simply connected gauge group and those with discrete symmetries. We provide a combinatorial explanation of this phenomenon for toric hypersurfaces. In particular this leads to a criterion to deduce Mordell-Weil torsion directly from the polytope. For all 3134 complete intersection genus-one curves in three-dimensional toric ambient spaces we confirm the conjecture by explicit calculation. We comment on several new features of these models: the Weierstrass forms of many models can be identified by relabeling the coefficient sections. This reduces the number of models to 1024 inequivalent ones. We give an example of a fiber which contains only non-toric sections one of which becomes toric when the fiber is realized in a different ambient space. Similarly a singularity in codimension one can have a toric resolution in one representation while it is non-toric in another. Finally we give a list of 24 inequivalent genus-one fibers that simultaneously exhibit multi-sections and Mordell-Weil torsion in the Jacobian. We discuss a self-mirror example from this list in detail.

  5. Neutrino-4 experiment on search for sterile neutrino with multi-section model of detector

    Science.gov (United States)

    Serebrov, A.; Ivochkin, V.; Samoilov, R.; Fomin, A.; Polyushkin, A.; Zinoviev, V.; Neustroev, P.; Golovtsov, V.; Chernyj, A.; Zherebtsov, O.; Martemyanov, V.; Tarasenkov, V.; Aleshin, V.; Petelin, A.; Izhutov, A.; Tuzov, A.; Sazontov, S.; Ryazanov, D.; Gromov, M.; Afanasiev, V.; Zaytsev, M.; Chaikovskii, M.

    2017-09-01

    In order to carry out research in the field of possible existence of a sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. The prototype of a multi-section neutrino detector with liquid scintillator volume of 350 l was installed in the middle of 2015. It is a moveable inside the passive shielding detector, which can be set at distance range from 6 to 11 meters from the reactor core. Measurements of antineutrino flux at such small distances from the reactor core are carried out with moveable detector for the first time. The measurements carried out with detector prototype demonstrated a possibility of measuring a reactor antineutrino flux in difficult conditions of cosmic background at Earth surface.

  6. Energy-efficient control of a multi-section supercapacitor power supply of an electric drive

    Directory of Open Access Journals (Sweden)

    Mozzhechkov Vladimir

    2018-01-01

    Full Text Available A method for synthesizing the control laws of a multi-section supercapacitor power supply of an electric drive is developed. The synthesized control law for an electric drive realizes the prescribed motion and minimizes the required capacitance of the power source. It is achieved through optimal disconnection and connection to the power line of the drive at designated times of one of the power supply sections. Reduction of the required capacitance of the power supply is achieved through a fuller discharge of some of its sections in motion conditions requiring a low level of electrical voltage and saving high voltage in other sections for the respective motion conditions. A mathematical formulation of the problem and a method of its solution is proposed. An example of the implementation of the proposed method is considered.

  7. Algorithm for Solution of Direct Kinematic Problem of Multi-sectional Manipulator with Parallel Structure

    Directory of Open Access Journals (Sweden)

    A. L. Lapikov

    2014-01-01

    Full Text Available The article is aimed at creating techniques to study multi-sectional manipulators with parallel structure. To solve this task the analysis in the field concerned was carried out to reveal both advantages and drawbacks of such executive mechanisms and main problems to be encountered in the course of research. The work shows that it is inefficient to create complete mathematical models of multisectional manipulators, which in the context of solving a direct kinematic problem are to derive a functional dependence of location and orientation of the end effector on all the generalized coordinates of the mechanism. The structure of multisectional manipulators was considered, where the sections are platform manipulators of parallel kinematics with six degrees of freedom. The paper offers an algorithm to define location and orientation of the end effector of the manipulator by means of iterative solution of analytical equation of the moving platform plane for each section. The equation for the unknown plane is derived using three points, which are attachment points of the moving platform joints. To define the values of joint coordinates a system of nine non-linear equations is completed. It is necessary to mention that for completion of the equation system are used the equations with the same type of non-linearity. The physical sense of all nine equations of the system is Euclidean distance between the points of the manipulator. The result of algorithm execution is a matrix of homogenous transformation for each section. The correlations describing transformations between adjoining sections of the manipulator are given. An example of the mechanism consisting of three sections is examined. The comparison of theoretical calculations with results obtained on a 3D-prototype is made. The next step of the work is to conduct research activities both in the field of dynamics of platform parallel kinematics manipulators with six degrees of freedom and in the

  8. Design and Analysis of a Bio-Inspired Wire-Driven Multi-Section Flexible Robot

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2013-04-01

    Full Text Available This paper presents a bio-inspired wire-driven multi-section flexible robot. It is inspired by the snake skeleton and octopus arm muscle arrangements. The robot consists of three sections and each section is made up of several identical vertebras, which are articulated by both spherical joints and a flexible backbone. Each section is driven by two groups of wires, controlling the bending motion in X and Y directions. This design integrates the serpentine robots' structure and the continuum robots' actuation. As a result, it is more compact than traditional serpentine robots and has a higher positioning accuracy than typical continuum soft robots, such as OctArm V. A Kinematics model and a workspace model of the robot are developed based on the piece wise constant curvature assumption. To evaluate the design, a prototype is built and experiments are carried out. The average distal end positioning error is less than 4%. Characteristics of the wire-driven robot are also discussed, including the leverage effect and the manipulability under constraint. These features makes the proposed robot well suited to confined spaces, especially for working in minimally invasive surgery, nuclear reactor pipelines, disaster debris, etc.

  9. Multi-section CT angiography compared with digital subtraction angiography in diagnosing major arterial hemorrhage in inflammatory pancreatic disease

    International Nuclear Information System (INIS)

    Hyare, Harpreet; Desigan, Sharmini; Nicholl, Helen; Guiney, Michael J.; Brookes, Jocelyn A.; Lees, William R.

    2006-01-01

    Purpose: Major arterial hemorrhage is an uncommon but serious complication of pancreatitis with high morbidity and mortality. Digital subtraction angiography (DSA) has long been the gold standard for the detection of a visceral artery pseudoaneurysm or for the site of active bleeding in patients with pancreatitis. Multi-section CT angiography is a minimally invasive technique which can provide high-resolution and high-contrast images of the arterial lumen and wall, with a much lower risk of complication and morbidity compared to DSA. The aim of this study was to determine the accuracy of multi-section CT angiography for the diagnosis of arterial complications of inflammatory pancreatitic disease. Materials and methods: A retrospective analysis of all patients undergoing visceral angiography for major bleeding as a complication of pancreatitis between 1998 and 2004 was performed. Twenty-nine studies in 25 patients (20 males, 5 females) with a mean age of 50.9 years (range 11-67 years) were identified where multi-section CT angiography was performed in the 24 h preceding the digital subtraction angiogram. Results: Digital subtraction angiography detected a pseudoaneurysm or contrast extravasation in 19 studies and no bleeding was demonstrated in 9 studies. CT angiography correctly identified the site and type of bleeding in 18 of the 19 positive studies. CT angiography detected extravasation of contrast in one study that was not demonstrated on digital subtraction angiography. The sensitivity and specificity for multi-section CT angiography for the detection of major arterial bleeding on a background of pancreatitis were 0.947 and 0.900, respectively. Conclusion: Multi-section CT angiography is a sensitive and accurate technique for the detection of major arterial hemorrhage in inflammatory pancreatic disease and should be considered as the first investigation in the management of these patients

  10. Ionizing and non-ionizing radiations

    International Nuclear Information System (INIS)

    1994-01-01

    The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

  11. Ionizing radiation

    International Nuclear Information System (INIS)

    Kruger, J.

    1989-01-01

    Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

  12. Ionizing radiations

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    This is an update about the radiological monitoring in base nuclear installations. A departmental order of the 23. march 1999 (J.O.28. april, p.6309) determines the enabling rules by the Office of Protection against Ionizing Radiations of person having at one's disposal the results with names of individual exposure of workers put through ionizing radiations. (N.C.)

  13. High-Energy 3D Calorimeter based on position-sensitive virtual Frisch-grid CdZnTe detectors for use in Gamma-ray Astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Alexey [Brookhaven National Lab. (BNL), Upton, NY (United States); De Geronimo, GianLuigi [Brookhaven National Lab. (BNL), Upton, NY (United States); Vernon, Emerson [Brookhaven National Lab. (BNL), Upton, NY (United States); Hays, Elizabeth [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Thompson, David [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); James, Ralph [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Moiseev, Alexander [Center for Research and Exploration; Technology, NASA Goddard Space Flight Center (GSFC) and Univ. of Maryland, Greenbelt, MD (United States)

    2017-08-12

    We present a concept for a calorimeter based on a novel approach of 3D position-sensitive virtual Frischgrid CZT detectors. This calorimeter aims to measure photons with energies from ~100 keV to 10 (goal 50) MeV. The expected energy resolution at 662 keV is ~1% FWHM, and the photon interaction positionmeasurement accuracy is ~1 mm in all 3 dimensions. Each CZT bar is a rectangular prism with typical cross-section of 6x6 mm2 and length of 2-4 cm. The bars are arranged in modules of 4 x 4 bars, and the modules themselves can be assembled into a larger array. The 3D virtual voxel approach solves a long-standing problem with CZT detectors associated with material imperfections that limit the performance and usefulness of relatively thick detectors (i.e., > 1 cm). Also, it allows us to relax the requirements on the quality of the crystals, maintaining good energy resolution and significantly reducing the instrument cost. Such a calorimeter can be successfully used in space telescopes that use Compton scattering of γ rays, such as AMEGO, serving as part of its calorimeter and providing the position and energy measurement for Compton-scattered photons. Also, it could provide suitable energy resolution to allow for spectroscopic measurements of γ-ray lines from nuclear decays. Another viable option is to use this calorimeter as a focal plane to conduct spectroscopic measurements of cosmic γ-ray events. In combination with a coded-aperture mask, it potentially could provide mapping of the 511-keV radiation from the Galactic Center region.

  14. Ionization chambers

    International Nuclear Information System (INIS)

    Boag, J.W.

    1987-01-01

    Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

  15. Calcium - ionized

    Science.gov (United States)

    ... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

  16. Ionization detector

    International Nuclear Information System (INIS)

    Solomon, E.E.

    1980-01-01

    A safe and reliable apparatus for detecting products of combustion and aerosols in the atmosphere was developed which uses a beta source. It is easy to adjust for optimum performance. The ionization detector comprises a double chamber; one of the chambers is the basic sensing chamber. The sensing chamber is ported to both the secondary chambers to account for slow ambient changes in the atmosphere outside of the chamber. The voltages from the ionization chamber are adjusted with electrodes in each chamber. The ionization chamber contains baffles to direct the air to be sensed as well as an electrostatic screen. A unique electronic circuit provides an inexpensive and reliable means for detecting the signal change which occurs in the ionization chamber. The decision level of the alarm circuit can be adjusted to allow for any desired sensitivity. (D.N.)

  17. Collisional ionization

    International Nuclear Information System (INIS)

    Arnaud, M.

    1985-07-01

    In low density, thin plasmas (such as stellar coronae, interstellar medium, intracluster medium) the ionization process is governed by collision between electrons and ions in their ground state. In view of the recent improvements we thought an updating of ionization rates was really needed. The work is based on both experimental data and theoretical works and give separate estimates for the direct and autoionization rates

  18. Ionization chamber

    International Nuclear Information System (INIS)

    Jilbert, P.H.

    1975-01-01

    The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

  19. Ionizing radiations

    International Nuclear Information System (INIS)

    Newton, W.

    1984-01-01

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

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

    International Nuclear Information System (INIS)

    Cermak, V.

    1975-01-01

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

  1. Ionizing radiation

    International Nuclear Information System (INIS)

    Dennis, J.A.

    1982-01-01

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

  2. Ionizing radiation

    Science.gov (United States)

    Tobias, C. A.; Grigoryev, Y. G.

    1975-01-01

    The biological effects of ionizing radiation encountered in space are considered. Biological experiments conducted in space and some experiences of astronauts during space flight are described. The effects of various levels of radiation exposure and the determination of permissible dosages are discussed.

  3. Ionization chamber

    International Nuclear Information System (INIS)

    1977-01-01

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

  4. Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

    DEFF Research Database (Denmark)

    Bach, L.; Kaiser, W.; Reithmaier, J.P.

    2003-01-01

    Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

  5. Ionization detector

    International Nuclear Information System (INIS)

    Steele, D.S.

    1987-01-01

    An ionization detector having an array of detectors has, for example, grounding pads positioned in the spaces between some detectors (data detectors) and other detectors (reference detectors). The grounding pads are kept at zero electric potential, i.e. grounded. The grounding serves to drain away electrons and thereby prevent an unwanted accumulation of charge in the spaces, and cause the electric field lines to be more perpendicular to the detectors in regions near the grounding pads. Alternatively, no empty space is provided there being additional, grounded, detectors provided between the data and reference detectors. (author)

  6. 37 GHz Direct-Modulation Bandwidth of Multi-Section InGaAsP/InP DBR-Laser with weakly coupled active grating section

    DEFF Research Database (Denmark)

    Kaiser, W.; Bach, L.; Reithmaier, J. P.

    2003-01-01

    37 GHz direct-modulation bandwidth could be obtained by a multi-section design with an integrated weakly coupled DBR grating. The laser shows side mode suppression ratios of 45 dB and output powers exceeding 20 mW....

  7. Measurement of Fragment Mass Distributions in Neutron-induced Fission of 238U and 232Th at Intermediate Energies

    International Nuclear Information System (INIS)

    Simutkin, V.D.

    2008-01-01

    Conceptual analysis of accelerator-driven systems assumes extensive use of nuclear data on neutron-induced reactions at intermediate energies. In particular, information about the fission fragment yields from the 238 U(n,f) and 232 Th(n,f) reactions is of particular interest at neutron energies from 10 to 200 MeV. However, there is a lack of such data for both 238 U and 232 Th. Up to now, the intermediate energy measurements have been performed for 238 U only, and there are no data for the 232 Th(n,f) reaction. The aim of the work is to provide such data. Fission fragment mass distributions for the 232 Th(n,f) and 238 U(n,f) reactions have been measured for the incident neutron energies 32.8 MeV, 45.3 MeV and 59.9 MeV. The experiments have been performed at the neutron beam facility of the Universite Catholique de Louvain, Belgium. A multi-section Frisch-gridded ionization chamber has been used as a fission fragment detector. The data obtained have been interpreted in terms of the multimodal random neck-rupture model (MMRNRM). (authors)

  8. Measurement of Fragment Mass Distributions in Neutron-induced Fission of {sup 238}U and {sup 232}Th at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Simutkin, V.D. [Uppsala University, P.O Box 525, SE-751 20 Uppsala (Sweden)

    2008-07-01

    Conceptual analysis of accelerator-driven systems assumes extensive use of nuclear data on neutron-induced reactions at intermediate energies. In particular, information about the fission fragment yields from the {sup 238}U(n,f) and {sup 232}Th(n,f) reactions is of particular interest at neutron energies from 10 to 200 MeV. However, there is a lack of such data for both {sup 238}U and {sup 232}Th. Up to now, the intermediate energy measurements have been performed for {sup 238}U only, and there are no data for the {sup 232}Th(n,f) reaction. The aim of the work is to provide such data. Fission fragment mass distributions for the {sup 232}Th(n,f) and {sup 238}U(n,f) reactions have been measured for the incident neutron energies 32.8 MeV, 45.3 MeV and 59.9 MeV. The experiments have been performed at the neutron beam facility of the Universite Catholique de Louvain, Belgium. A multi-section Frisch-gridded ionization chamber has been used as a fission fragment detector. The data obtained have been interpreted in terms of the multimodal random neck-rupture model (MMRNRM). (authors)

  9. Ionizing radiations

    International Nuclear Information System (INIS)

    2009-01-01

    After having recalled some fundamental notions and measurement units related to ionizing radiations, this document describes various aspects of natural and occupational exposures: exposure modes and sources, exposure levels, biological effects, health impacts. Then, it presents prevention principles aimed at, in an occupational context of use of radiation sources (nuclear industry excluded), reducing and managing these exposures: risk assessment, implementation of safety from the front end. Some practical cases illustrate the radiation protection approach. The legal and regulatory framework is presented: general notions, worker exposure, measures specific to some worker categories (pregnant and breast feeding women, young workers, temporary workers). A last part describes what is to be done in case of incident or accident (dissemination of radioactive substances from unsealed sources, anomaly occurring when using a generator or a sealed source, post-accident situation)

  10. Ring magnetron ionizer

    International Nuclear Information System (INIS)

    Alessi, J.G.

    1986-01-01

    A ring magnetron D - charge exchange ionizer has been built and tested. An H - current of 500 μA was extracted with an estimated H 0 density in the ionizer of 10 12 cm -3 . This exceeds the performance of ionizers presently in use on polarized H - sources. The ionizer will soon be tested with a polarized atomic beam

  11. Ionization of food products

    International Nuclear Information System (INIS)

    Vasseur, J.P.

    1991-01-01

    After general remarks on foods preservation, on international works and on ionization future prospects, main irradiation sources are described. Recalls on radioactivity, on radiation-matter interaction, on toxicology of ionized foods and on ionized foods detection are given. Ionization applications to various products are reviewed, especially in: - Poultry meat - Fishing products - Fresh fruits and vegetables - Dry fruits and vegetables - spices, tea, infusion - prepacked products... An evaluation of economics and sociocultural impacts is presented in connection with recent experiments [fr

  12. Foodstuffs preservation by ionization

    International Nuclear Information System (INIS)

    1991-12-01

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

  13. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    CERN Document Server

    Troyer, G L

    2000-01-01

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% (at) 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse r...

  14. Ionizing radiation in environment

    International Nuclear Information System (INIS)

    Jandl, J.; Petr, I.

    1988-01-01

    The basic terms are explained such as the atom, radioactivity, nuclear reaction, interaction of ionizing radiation with matter, etc. The basic dosimetric variables and units and properties of radionuclides and ionizing radiation are given. Natural and artificial sources of ionizing radiation are discussed with regard to the environment and the propagation and migration of radionuclides is described in the environment to man. The impact is explained of ionizing radiation on the cell and the somatic and genetic effects of radiation on man are outlined. Attention is devoted to protection against ionizing radiation and to radiation limits, also to the detection, dosimetry and monitoring of ionizing radiation in the environment. (M.D.). 92 figs., 40 tabs. 74 refs

  15. Ionizing radiation in hospitals

    International Nuclear Information System (INIS)

    Blok, K.; Ginkel, G. van; Leun, K. van der; Muller, H.; Oude Elferink, J.; Vesseur, A.

    1985-10-01

    This booklet dels with the risks of the use of ionizing radiation for people working in a hospital. It is subdivided in three parts. Part 1 treats the properties of ionizing radiation in general. In part 2 the various applications are discussed of ionizing radiation in hospitals. Part 3 indicates how a not completely safe situation may be improved. (H.W.). 14 figs.; 4 tabs

  16. Solid oxide fuel cell power plant having a fixed contact oxidation catalyzed section of a multi-section cathode air heat exchanger

    Science.gov (United States)

    Saito, Kazuo; Lin, Yao

    2015-02-17

    The multi-section cathode air heat exchanger (102) includes at least a first heat exchanger section (104), and a fixed contact oxidation catalyzed section (126) secured adjacent each other in a stack association. Cool cathode inlet air flows through cool air channels (110) of the at least first (104) and oxidation catalyzed sections (126). Hot anode exhaust flows through hot air channels (124) of the oxidation catalyzed section (126) and is combusted therein. The combusted anode exhaust then flows through hot air channels (112) of the first section (104) of the cathode air heat exchanger (102). The cool and hot air channels (110, 112) are secured in direct heat exchange relationship with each other so that temperatures of the heat exchanger (102) do not exceed 800.degree. C. to minimize requirements for using expensive, high-temperature alloys.

  17. Dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    Musilek, L.; Seda, J.; Trousil, J.

    1992-01-01

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

  18. Improvements in ionization chambers

    International Nuclear Information System (INIS)

    Whetten, N.R.; Zubal, C.

    1980-01-01

    A method of reducing mechanical vibrations transmitted to the parallel plate electrodes of ionization chamber x-ray detectors, commonly used in computerized x-ray axial tomography systems, is described. The metal plate cathodes and anodes are mounted in the ionizable gas on dielectric sheet insulators consisting of a composite of silicone resin and glass fibres. (UK)

  19. Dual ionization chamber

    International Nuclear Information System (INIS)

    Mallory, J.; Turlej, Z.

    1981-01-01

    Dual ionization chambers are provided for use with an electronic smoke detector. The chambers are separated by electrically-conductive partition. A single radiation source extends through the partition into both chambers, ionizing the air in each. The mid-point current of the device may be balanced by adjusting the position of the source

  20. Introduction to ionizing radiation physics

    International Nuclear Information System (INIS)

    Musilek, L.

    1979-01-01

    Basic properties are described of the atom, atomic nucleus and of ionizing radiation particles; nuclear reactions, ionizing radiation sources and ionizing radiation interaction with matter are explained. (J.P.)

  1. Biological Effects of Ionizing Radiation

    Science.gov (United States)

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

    1952-04-07

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

  2. Miniature ionization chamber

    International Nuclear Information System (INIS)

    Alexeev, V.I.; Emelyanov, I.Y.; Ivanov, V.M.; Konstantinov, L.V.; Lysikov, B.V.; Postnikov, V.V.; Rybakov, J.V.

    1976-01-01

    A miniature ionization chamber having a gas-filled housing which accommodates a guard electrode made in the form of a hollow perforated cylinder is described. The cylinder is electrically associated with the intermediate coaxial conductor of a triaxial cable used as the lead-in of the ionization chamber. The gas-filled housing of the ionization chamber also accommodates a collecting electrode shaped as a rod electrically connected to the center conductor of the cable and to tubular members. The rod is disposed internally of the guard electrode and is electrically connected, by means of jumpers passing through the holes in the guard electrode, to the tubular members. The tubular members embrace the guard electrode and are spaced a certain distance apart along its entire length. Arranged intermediate of these tubular members are spacers secured to the guard electrode and fixing the collecting electrode throughout its length with respect to the housing of the ionization chamber

  3. What is ''ionizing radiation''?

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1997-01-01

    The scientific background of radiation protection and hence ''ionizing radiation'' is undergoing substantial regress since a century. Radiations as we are concerned with are from the beginning defined based upon their effects rather than upon the physical origin and their properties. This might be one of the reasons why the definition of the term ''ionizing radiation'' in radiation protection is still weak from an up to date point of view in texts as well as in international and national standards. The general meaning is unambiguous, but a numerical value depends on a number of conditions and the purpose. Hence, a clear statement on a numerical value of the energy threshold beyond a radiation has to be considered as ''ionizing'' is still missing. The existing definitions are, therefore, either correct but very general or theoretical and hence not applicable. This paper reviews existing definitions and suggests some issues to be taken into account for possible improvement of the definition of ''ionizing radiation''. (author)

  4. 'Saddle-point' ionization

    International Nuclear Information System (INIS)

    Gay, T.J.; Hale, E.B.; Irby, V.D.; Olson, R.E.; Missouri Univ., Rolla; Berry, H.G.

    1988-01-01

    We have studied the ionization of rare gases by protons at intermediate energies, i.e., energies at which the velocities of the proton and the target-gas valence electrons are comparable. A significant channel for electron production in the forward direction is shown to be 'saddle-point' ionization, in which electrons are stranded on or near the saddle-point of electric potential between the receding projectile and the ionized target. Such electrons yield characteristic energy spectra, and contribute significantly to forward-electron-production cross sections. Classical trajectory Monte Carlo calculations are found to provide qualitative agreement with our measurements and the earlier measurements of Rudd and coworkers, and reproduce, in detail, the features of the general ionization spectra. (orig.)

  5. Ionization particle detector

    International Nuclear Information System (INIS)

    Ried, L.

    1982-01-01

    A new device is claimed for detecting particles in a gas. The invention comprises a low cost, easy to assemble, and highly accurate particle detector using a single ionization chamber to contain a reference region and a sensing region. The chamber is designed with the radioactive source near one electrode and the second electrode located at a distance less than the distance of maximum ionization from the radioactive source

  6. The critical ionization velocity

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1980-06-01

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

  7. Ionization front accelerator

    International Nuclear Information System (INIS)

    Olson, C.L.

    1975-01-01

    In a recently proposed linear collective accelerator, ions are accelerated in a steep, moving potential well created at the head of an intense relativistic electron beam. The steepness of the potential well and its motion are controlled by the external ionization of a suitable background gas. Calculations concerning optimum choices for the background gas and the ionization method are presented; a two-step photoionization process employing Cs vapor is proposed. In this process, a super-radiant light source is used to excite the gas, and a UV laser is used to photoionize the excited state. The appropriate line widths and coupled ionization growth rate equations are discussed. Parameter estimates are given for a feasibility experiment, for a 1 GeV proton accelerator, and for a heavy ion accelerator (50 MeV/nucleon uranium). (auth)

  8. The ionizing treatment of food

    International Nuclear Information System (INIS)

    1998-01-01

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

  9. Ambient ionization mass spectrometry

    International Nuclear Information System (INIS)

    Lebedev, A T

    2015-01-01

    Ambient ionization mass spectrometry emerged as a new scientific discipline only about ten years ago. A considerable body of information has been reported since that time. Keeping the sensitivity, performance and informativity of classical mass spectrometry methods, the new approach made it possible to eliminate laborious sample preparation procedures and triggered the development of miniaturized instruments to work directly in the field. The review concerns the theoretical foundations and design of ambient ionization methods. Their advantages and drawbacks, as well as prospects for application in chemistry, biology, medicine, environmetal analysis, etc., are discussed. The bibliography includes 194 references

  10. Liquid ionizing radiaion detector

    International Nuclear Information System (INIS)

    deGaston, A.N.

    1979-01-01

    A normally nonconducting liquid such as liquid hydrocarbon is encased between a pair of electrodes in an enclosure so that when the liquid is subjected to ionizing radiation, the ion pairs so created measurably increase the conductivity of the fluid. The reduced impedance between the electrodes is detectable with a sensitive ohm-meter and indicates the amount of ionizing radiation. The enclosure, the electrodes and the fluid can be constructed of materials that make the response of the detector suitable for calibrating a large range of radiation energy levels. The detector is especially useful in medical applications where tissue equivalent X ray detectors are desired

  11. Radiation dependent ionization model

    International Nuclear Information System (INIS)

    Busquet, M.

    1991-01-01

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

  12. Ionizing Radiation Processing Technology

    International Nuclear Information System (INIS)

    Rida Tajau; Kamarudin Hashim; Jamaliah Sharif; Ratnam, C.T.; Keong, C.C.

    2017-01-01

    This book completely brief on the basic concept and theory of ionizing radiation in polymers material processing. Besides of that the basic concept of polymerization addition, cross-linking and radiation degradation also highlighted in this informative book. All of the information is from scientific writing based on comprehensive scientific research in polymerization industry which using the radiation ionizing. It is very useful to other researcher whose study in Nuclear Sciencea and Science of Chemical and Material to use this book as a guideline for them in future scientific esearch.

  13. Contact ionization ion source

    International Nuclear Information System (INIS)

    Hashmi, N.; Van Der Houven Van Oordt, A.J.

    1975-01-01

    An ion source in which an apertured or foraminous electrode having a multiplicity of openings is spaced from one or more active surfaces of an ionisation electrode, the active surfaces comprising a material capable of ionising by contact ionization a substance to be ionized supplied during operation to the active surface or surfaces comprises means for producing during operation a magnetic field which enables a stable plasma to be formed in the space between the active surface or surfaces and the apertured electrode, the field strength of the magnetic field being preferably in the range between 2 and 8 kilogauss. (U.S.)

  14. Multiple sampling ionization chamber (MUSIC) for investigation of fusion induced by halo nuclei

    International Nuclear Information System (INIS)

    Petrascu, H.; Kumagai, H.; Tanihata, I.; Fueloep, Zs.; Petrascu, M.

    1999-01-01

    A high resolution MUSIC for low and medium energy ions up to ∼ 20 AMeV, for investigation of fusion processes induced by halo nuclei, has been achieved. The chamber was used in the first experiments, aiming at investigating fusion processes induced by 9,11 Li with light targets. In these experiments MUSIC was used for the identification of the inclusive evaporation residues produced in the Si detector target, mounted inside the chamber. By using MUSIC it was possible to separate the inclusive spectra corresponding to the fusion processes, from the background due to the energy degraded beam particles. In principle such a chamber could be also used for investigation of particular fusion channels produced in the entrance window. In this case one could obtain the fusion product trajectory angle with the horizontal plane, by coupling each anode pad to a TDC. The chamber was also provided by a position grid, mounted between the Frisch grid and the anode pads. The energy loss distribution widths were measured using α particles. The chamber was filled with P-10 gas at pressures between 200 and 300 torr. The obtained resolution corresponding to a single pad, is close to the limit derived from the theory of Badhwar. (authors)

  15. Investigation of the far asymmetric region in 252Cf(sf)

    International Nuclear Information System (INIS)

    Hambsch, F.-J.; Oberstedt, S.

    1997-01-01

    A twin Frisch-gridded ionization chamber has been used to measure the fission fragment mass, kinetic-energy and angular correlations for 252 Cf(sf). In total 2.5 x 10 8 events were collected. The focus was in the far asymmetric mass region, where enhancements in the yield had been found earlier. It could be shown, that these findings are due to false events, coming from either close geometries not properly taking into account the angular-dependent energy loss in the sample and backing, from a too large angular cone selected in case of studies employing ionization chambers, or even from poor target qualities. (orig.)

  16. Detection of ionized foods

    International Nuclear Information System (INIS)

    Beerens, H.

    1986-01-01

    Irradiated foods and feed might be identified with two kinds of tests: 1. biochemical: detection of specific products are not yet available 2. microbiological: when a microbial species dissapears from a sample of food i.e. it is not detectable after enrichment (for instance Coliforms in hamburgers) it is likely that the sample has been ionized [fr

  17. Ionization loss in BGO

    International Nuclear Information System (INIS)

    Bakken, J.A.; Denes, P.; Piroue, P.A.; Stickland, D.P.; Sumner, R.L.; Taylor, C.; Barone, L.; Borgia, B.; Diemoz, M.; Dionisi, C.; Falciano, S.; Ferroni, F.; Gratta, G.; Longo, E.; Luminari, L.; Morganti, S.; Valente, E.; Blaising, J.J.; Boutigny, D.; Coignet, G.; Karyotakis, Y.; Sauvage, G.; Schneegans, M.; Vivargent, M.; Extermann, P.; Morand, G.; Ossmann, J.; Ruckstuhl, W.; Schaad, T.P.; Lecoq, P.; Walk, W.; Li, P.J.; Micke, M.; Micke, U.; Schmitz, D.

    1988-01-01

    We report on a precise measurement of the energy loss through ionization by pions in bismuth germanate performed at several values of the incident particles momentum with a prototype of the L3 electromagnetic calorimeter. The experimental results are in good agreement with theoretical predictions showing the relativistic rise modified by density effect. (orig.)

  18. Ionizing radiation from tobacco

    International Nuclear Information System (INIS)

    Westin, J.B.

    1987-01-01

    Accidents at nuclear power facilities seem inevitably to bring in their wake a great deal of concern on the part of both the lay and medical communities. Relatively little attention, however, is given to what may be the largest single worldwide source of effectively carcinogenic ionizing radiation: tobacco. The risk of cancer deaths from the Chernobyl disaster are tobacco smoke is discussed

  19. Ionization beam scanner

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

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

  20. Basic ionizing radiation symbol

    International Nuclear Information System (INIS)

    1987-01-01

    A description is given of the standard symbol for ionizing radiation and of the conditions under which it should not be used. The Arabic equivalent of some English technical terms in this subject is given in one page. 1 ref., 1 fig

  1. Ionizing radiation and life.

    Science.gov (United States)

    Dartnell, Lewis R

    2011-01-01

    Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and the origins of life. This review surveys the role of CR and mineral radioactivity in star formation, generation of biogenic elements, and the synthesis of organic molecules and driving of prebiotic chemistry. Another major theme is the multiple layers of shielding of planetary surfaces from the flux of cosmic radiation and the various effects on a biosphere of violent but rare astrophysical events such as supernovae and gamma-ray bursts. The influences of CR can also be duplicitous, such as limiting the survival of surface life on Mars while potentially supporting a subsurface biosphere in the ocean of Europa. This review highlights the common thread that ionizing radiation forms between the disparate component disciplines of astrobiology. © Mary Ann Liebert, Inc.

  2. Ionization chamber smoke detectors

    International Nuclear Information System (INIS)

    1988-03-01

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

  3. III-nitride Photonic Integrated Circuit: Multi-section GaN Laser Diodes for Smart Lighting and Visible Light Communication

    KAUST Repository

    Shen, Chao

    2017-04-01

    The past decade witnessed the rapid development of III-nitride light-emitting diodes (LEDs) and laser diodes (LDs), for smart lighting, visible-light communication (VLC), optical storage, and internet-of-things. Recent studies suggested that the GaN-based LDs, which is free from efficiency droop, outperform LEDs as a viable high-power light source. Conventionally, the InGaN-based LDs are grown on polar, c-plane GaN substrates. However, a relatively low differential gain limited the device performance due to a significant polarization field in the active region. Therefore, the LDs grown on nonpolar m-plane and semipolar (2021)-plane GaN substrates are posed to deliver high-efficiency owing to the entirely or partially eliminated polarization field. To date, the smart lighting and VLC functionalities have been demonstrated based on discrete devices, such as LDs, transverse-transmission modulators, and waveguide photodetectors. The integration of III-nitride photonic components, including the light emitter, modulator, absorber, amplifier, and photodetector, towards the realization of III-nitride photonic integrated circuit (PIC) offers the advantages of small-footprint, high-speed, and low power consumption, which has yet to be investigated. This dissertation presents the design, fabrication, and characterization of the multi-section InGaN laser diodes with integrated functionalities on semipolar (2021)-plane GaN substrates for enabling such photonic integration. The blue-emitting integrated waveguide modulator-laser diode (IWM-LD) exhibits a high modulation efficiency of 2.68 dB/V. A large extinction ratio of 11.3 dB is measured in the violet-emitting IWM-LD. Utilizing an integrated absorber, a high optical power (250mW), droop-free, speckle-free, and large modulation bandwidth (560MHz) blue-emitting superluminescent diode is reported. An integrated short-wavelength semiconductor optical amplifier with the laser diode at ~404 nm is demonstrated with a large gain of 5

  4. Ionization of Interstellar Hydrogen

    Science.gov (United States)

    Whang, Y. C.

    1996-09-01

    Interstellar hydrogen can penetrate through the heliopause, enter the heliosphere, and may become ionized by photoionization and by charge exchange with solar wind protons. A fluid model is introduced to study the flow of interstellar hydrogen in the heliosphere. The flow is governed by moment equations obtained from integration of the Boltzmann equation over the velocity space. Under the assumption that the flow is steady axisymmetric and the pressure is isotropic, we develop a method of solution for this fluid model. This model and the method of solution can be used to study the flow of neutral hydrogen with various forms of ionization rate β and boundary conditions for the flow on the upwind side. We study the solution of a special case in which the ionization rate β is inversely proportional to R2 and the interstellar hydrogen flow is uniform at infinity on the upwind side. We solve the moment equations directly for the normalized density NH/NN∞, bulk velocity VH/VN∞, and temperature TH/TN∞ of interstellar hydrogen as functions of r/λ and z/λ, where λ is the ionization scale length. The solution is compared with the kinetic theory solution of Lallement et al. The fluid solution is much less time-consuming than the kinetic theory solutions. Since the ionization rate for production of pickup protons is directly proportional to the local density of neutral hydrogen, the high-resolution solution of interstellar neutral hydrogen obtained here will be used to study the global distribution of pickup protons.

  5. Equipment for handling ionization chamber

    International Nuclear Information System (INIS)

    Altmann, J.

    1988-01-01

    The device consists of an ionization channel with an ionization chamber, of a support ring, axial and radial bearings, a sleeve, a screw gear and an electric motor. The ionization chamber is freely placed on the bottom of the ionization channel. The bottom part of the channel deviates from the vertical axis. The support ring propped against the axial bearing in the sleeve is firmly fixed to the top part of the ionization channel. The sleeve is fixed to the reactor lid. Its bottom part is provided with a recess for the radial bearing which is propped against a screw wheel firmly connected to the ionization channel. In measuring neutron flux, the screw wheel is rotated by the motor, thus rotating the whole ionization channel such that the ionization chamber is displaced into the reactor core.(J.B.). 1 fig

  6. Epidemiology and ionizing radiations

    International Nuclear Information System (INIS)

    Bourguignon, M.; Masse, R.; Slama, R.; Spira, A.; Timarche, M.; Laurier, D.; Billon, S.; Rogel, A.; Telle Lamberton, M.; Catelinois, O.; Thierry, I.; Grosche, B.; Ron, E.; Vathaire, F. de; Cherie Challine, L.; Donadieu, J.; Pirard, Ph.; Bloch, J.; Setbon, M.

    2004-01-01

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

  7. Gridded ionization chamber

    International Nuclear Information System (INIS)

    Houston, J.M.

    1977-01-01

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

  8. Sensor for ionizable elements

    International Nuclear Information System (INIS)

    Berkey, E.; Reed, W.A. III; Hickam, W.M.

    1977-01-01

    Sensor to detect thermally ionizable elements or molucules in air, water vapour or oxygen or to be used as alkali leak detector in vacuum systems, e.g. in the pipe system of a liquid-metal cooled FBR. The sensor consists of an filament made of thorium-containing iridium as cathode with a temperature upto 1000 0 C and an anode sheet of molybdenum, nickel or stainless steal. (ORU) [de

  9. Gridded Ionization Chamber

    International Nuclear Information System (INIS)

    Manero Amoros, F.

    1962-01-01

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

  10. Pregnancy and ionizing radiation

    International Nuclear Information System (INIS)

    Plataniotis, Th.N.; Nikolaou, K.I.; Syrgiamiotis, G.V.; Dousi, M.; Panou, Th.; Georgiadis, K.; Bougias, C.

    2008-01-01

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

  11. Non-ionizing radiation

    International Nuclear Information System (INIS)

    Fischer, P.G.

    1983-01-01

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

  12. Ionization of anisothermal plasmas

    International Nuclear Information System (INIS)

    Dennery, F.M.

    1994-01-01

    During this last mid-century, only the temperature of electrons has been involved in the Saha's mass action law, whatever be the other ionic and neutral ones in any isothermal or anisothermal plasma. In order to set aside this underlying paradox in the case of argon ionization, it is necessary to improve this equation of partial equilibrium after having defined: - the basic Gibbs-Duhem's relations for such a polythermal mixture, - the inhomogeneous equilibrium issued from chemical reactions according to Le Chatelier's principle. (author). 3 refs

  13. Ionization detectors, ch. 3

    International Nuclear Information System (INIS)

    Sevcik, J.

    1976-01-01

    Most measuring devices used in gas chromatography consist of detectors that measure the ionization current. The process is based on the collision of a moving high-energy particle with a target particle that is ionised while an electron is freed. The discussion of the conditions of the collision reaction, the properties of the colliding particles, and the intensity of the applied field point to a unified classification of ionisation detectors. Radioactive sources suitable for use in these detectors are surveyed. The slow-down mechanism, recombination and background current effect are discussed

  14. Multiple chamber ionization detector

    International Nuclear Information System (INIS)

    Solomon, E.E.

    1982-01-01

    An ionization smoke detector employs a single radiation source in a construction comprising at least two chambers with a center or node electrode. The radioactive source is associated with this central electrode, and its positioning may be adjusted relative to the electrode to alter the proportion of the source that protrudes into each chamber. The source may also be mounted in the plane of the central electrode, and positioned relative to the center of the electrode. The central electrode or source may be made tiltable relative to the body of the detector

  15. Personnel ionizing radiation dosimeter

    International Nuclear Information System (INIS)

    Williams, R.A.

    1975-01-01

    A dosimeter and method for use by personnel working in an area of mixed ionizing radiation fields for measuring and/or determining the effective energy of x- and gamma radiation; beta, x-, and gamma radiation dose equivalent to the surface of the body; beta, x-, and gamma radiation dose equivalent at a depth in the body; the presence of slow neutron, fast neutron dose equivalent; and orientation of the person wearing the dosimeter to the source of radiation is disclosed. Optionally integrated into this device and method are improved means for determining neutron energy spectrum and absorbed dose from fission gamma and neutron radiation resulting from accidental criticality

  16. Doubly resonant multiphoton ionization

    International Nuclear Information System (INIS)

    Crance, M.

    1978-01-01

    A particular case of doubly resonant multiphoton ionization is theoretically investigated. More precisely, two levels quasi-resonant with two successive harmonics of the field frequency are considered. The method used is based on the effective operator formalism first introduced for this problem by Armstrong, Beers and Feneuille. The main result is to show the possibility of observing large interference effects on the width of the resonances. Moreover this treatment allows us to make more precise the connection between effective operator formalism and standard perturbation theory

  17. Plasma production via field ionization

    Directory of Open Access Journals (Sweden)

    C. L. O’Connell

    2006-10-01

    Full Text Available Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch, or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam’s bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

  18. Biology of ionizing radiation effects

    International Nuclear Information System (INIS)

    Ferradini, C.; Pucheault, J.

    1983-01-01

    The present trends in biology of ionizing radiation are reviewed. The following topics are investigated: interaction of ionizing radiations with matter; the radiolysis of water and aqueous solutions; properties of the free radicals intervening in the couples O 2 /H 2 O and H 2 O/H 2 ; radiation chemistry of biological compounds; biological effects of ionizing radiations; biochemical mechanisms involving free radicals as intermediates; applications (biotechnological applications, origins of life) [fr

  19. News about ionized food identification

    International Nuclear Information System (INIS)

    Raffi, J.

    1995-01-01

    The ionizing radiations are used to clean food and increase their preservation life. If a lot of countries permits ionized products commercialization, others are opposed to it. To control the commercial exchanges, check the applied treatment aim and give to the consumers a better information, several ionized food identification methods were perfected and several are about to be recognized as european standards. 4 refs. 3 figs, 1 tab

  20. Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

    Science.gov (United States)

    Tovesson, F.; Duke, D.; Geppert-Kleinrath, V.; Manning, B.; Mayorov, D.; Mosby, S.; Schmitt, K.

    2018-03-01

    Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

  1. Prompt neutron emission from fragments in spontaneous fission of {sup 244,248}Cm and {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Vorobyev, A. S.; Shcherbakov, O. A. [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, 188300 (Russian Federation); Dushin, V. N.; Jakovlev, V. A.; Kalinin, V. A.; Petrov, B. F. [V.G. Khlopin Radium Institute, St. Petersburg, 194021 (Russian Federation); Hambsch, F.J [EC-JRC-Institute for Reference Materials and Measurements Retieseweg 111, B-2440 Geel (Belgium); Laptev, A. B. [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, 188300 (Russian Federation); Japan Nuclear Cycle Development Institute, Tokai-mura, Naka-gun, Ibaraki 319-1194 (Japan)

    2005-07-01

    Neutrons emitted in fission were measured separately for each complementary fragment in correlation with fission fragment energies. Two high efficiency Gd-loaded liquid scintillator tanks were used for neutron registration. Fission fragment energies were measured using a twin Frisch gridded ionization chamber with a pin-hole collimator. The neutron multiplicity distributions were obtained for each value of the fission fragment mass and energy and corrected for neutron registration efficiency, background and pile-up. The dependencies of these distributions on fragment mass and energy for different energy and mass bins, as well as the mass and energy distribution of the fission fragments are presented and discussed. (authors)

  2. Soil contamination studies

    International Nuclear Information System (INIS)

    1997-06-01

    The objective of this project was to develop a quick screening method that accurately identifies and quantifies the amount of alpha-emitting radionuclides in infinitely-thick soil samples using a Frisch grid ionization chamber. An additional objective of the work was to provide the US Department of Energy, Nevada Operations Office and its contractors with information on the theoretical and actual measured results of atmospheric testing contamination of soil and water at the Nevada Test Site through a comprehensive search of existing literature

  3. Measurements of neutron-induced fission cross sections of Pb and Bi at intermediate energies

    International Nuclear Information System (INIS)

    Ryzhov, Igor; Tutin, Gennady; Eismont, Vilen; Mitryukhin, Andrey; Oplavin, Valery; Soloviev, Sergey; Conde, Henri; Olsson, Nils; Renberg, Per-Ulf

    2002-01-01

    Neutron-induced fission cross sections of nat Pb and 209 Bi have been measured relative to the 238 U(n.f) cross section at energies 96 MeV for lead and 133 MeV for bismuth. The measurements were performed at the quasi-mono-energetic neutron beam facility of The Svedberg Laboratory in Uppsala using Frisch-gridded ionization chamber. The results obtained are compared with other experimental data. The present state of the Bi standard recommended by IAEA is discussed. (author)

  4. Resonance ionization spectroscopy 1990

    International Nuclear Information System (INIS)

    Parks, J.E.; Omenetto, N.

    1991-01-01

    The Fifth International Symposium on Resonance Ionization Spectroscopy (RIS) and its Applications was held in Varese, Italy, 16-21 September 1990. Interest in RIS and its applications continues to grow, and RIS is expanding into a more diverse and mature field of study. This maturity was evident in this meeting both in the basic science and understanding of RIS processes and in the number of new and improved applications and techniques. The application of RIS techniques to molecular detection problems made remarkable progress since the last meeting two years ago. Subtle effects pertaining to isotopic discrimination received more theoretical attention, and there now seems to be good understanding of these effects, which can lead to correction procedures and/or methods to avoid isotopic effects. RIS applications were presented in which significant, real world problems were addressed, demonstrating its capability to solve problems that previously could not be accurately solved by other more traditional techniques. The contributions to the conference are grouped under the following major topic headings: physics applications of rare atoms; laser ionization mechanisms - spectroscopy; atomic, molecular and ion sources; molecular RIS; atomic RIS - Rydberg states; environmental trace analysis; biological and medical applications; state selected chemistry; new laser sources and techniques; ultra-high resolution and isotopic selectivity; surface and bulk analysis. (Author)

  5. Hygiene of ionizing radiations

    International Nuclear Information System (INIS)

    Legare, I.-M.; Conceicao Cunha, M. da

    1976-01-01

    The concepts of quality factor and rem are introduced and a table of biological effects of external ionizing radiation sources is presented. Natural exposures, with tables of background radiation sources and of doses due to cosmic rays on high altitude areas and their populations are treated, as well as medical exposures; artificial background; fallout; scientific, industrial and other sources. The maximum and limit doses for man are given and tables of maximum admissible doses of ionizing radiations for 16-18 year old workers professionaly exposed, for professionals eventually subjected to radiation in their work and for people eventually exposed. Professional protection is discussed and tables are given of half-value layer of water, concrete, iron and lead for radiations of different energies, as well as the classification of exposure zones to the radiations and of maximum acceptable contamination for surfaces. The basic safety standards for radiation protection are summarized; tables are given also with emergency references for internal irradiation. Procedures with patients which received radioisotopes are discussed. At last, consideration is given to the problem of radioactive wastes in connection with the medical use of radionuclides [pt

  6. Foundations of ionizing radiation dosimetry

    International Nuclear Information System (INIS)

    Denisenko, O.N.; Pereslegin, I.A.

    1985-01-01

    Foundations of dosimetry in application to radiotherapy are presented. General characteristics of ionizing radiations and main characteristics of ionizing radiation sources, mostly used in radiotherapy, are given. Values and units for measuring ionizing radiation (activity of a radioactive substance, absorbed dose, exposure dose, integral dose and dose equivalent are considered. Different methods and instruments for ionizing radiation dosimetry are discussed. The attention is paid to the foundations of clinical dosimetry (representation of anatomo-topographic information, choice of radiation conditions, realization of radiation methods, corrections for a configuration and inhomogeneity of a patient's body, account of biological factors of radiation effects, instruments of dose field formation, control of irradiation procedure chosen)

  7. [Ionizing and non-ionizing radiation (comparative risk estimations)].

    Science.gov (United States)

    Grigor'ev, Iu G

    2012-01-01

    The population has widely used mobile communication for already more than 15 years. It is important to note that the use of mobile communication has sharply changed the conditions of daily exposure of the population to EME We expose our brain daily for the first time in the entire civilization. The mobile phone is an open and uncontrollable source of electromagnetic radiation. The comparative risk estimation for the population of ionizing and non-ionizing radiation was carried out taking into account the real conditions of influence. Comparison of risks for the population of ionizing and non-ionizing radiation leads us to a conclusion that EMF RF exposure in conditions of wide use of mobile communication is potentially more harmful than ionizing radiation influence.

  8. Applications of ionizing radiations

    International Nuclear Information System (INIS)

    2014-01-01

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

  9. Reference ionization chamber

    International Nuclear Information System (INIS)

    Golnik, N.; Zielczynski, M.

    1999-01-01

    The paper presents the design of ionization chamber devoted for the determination of the absolute value of the absorbed dose in tissue-equivalent material. The special attention was paid to ensure that the volume of the active gas cavity was constant and well known. A specific property of the chamber design is that the voltage insulators are 'invisible' from any point of the active volume. Such configuration ensures a very good time stability of the electrical field and defines the active volume. The active volume of the chamber was determined with accuracy of 0.3%. This resulted in accuracy of 0.8% in determination of the absorbed dose in the layer of material adherent to the gas cavity. The chamber was applied for calibration purposes at radiotherapy facility in Joint Institute for Nuclear Research in Dubna (Russia) and in the calibration laboratory of the Institute of Atomic Energy in Swierk. (author)

  10. Applications of ionizing radiations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-07-01

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

  11. Ionizing radiation detector

    Science.gov (United States)

    Thacker, Louis H.

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  12. Transport processes in ionized gases

    International Nuclear Information System (INIS)

    Kremer, G.M.

    1997-01-01

    Based on kinetic theory of gases and on the combined of Chapman-Enskog and Grad, the laws of Ohm, Fourier and Navier-Stokes are derived for a non-relativistic fully ionized gas. Moreover, the combined method is applied to the BGK model of the relativistic Boltzmann equation and the Ohm's law is derived for a relativistic fully ionized gas. (author)

  13. Amorphous silicon ionizing particle detectors

    Science.gov (United States)

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  14. Worldwide exposures to ionizing radiation

    International Nuclear Information System (INIS)

    Bennett, B.G.

    1993-01-01

    All of mankind is exposed to ionizing radiation from natural sources, from human practices that release natural and artificial radionuclides to the environment, and from medical radiation procedures. This paper reviews the assessment in the UNSCEAR 1993 Report of the exposures of human populations worldwide to the various sources of ionizing radiation

  15. Food ionizing treatment

    International Nuclear Information System (INIS)

    Strasser, A.; Raffi, J.; Hasselmann, C.

    1997-01-01

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

  16. Ionization detection system for aerosols

    International Nuclear Information System (INIS)

    Jacobs, M.E.

    1977-01-01

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber. 8 claims, 7 figures

  17. Laser-enhanced ionization spectroscopy around the ionization limit

    International Nuclear Information System (INIS)

    Axner, O.; Berglind, T.; Sjoestroem, S.

    1986-01-01

    Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

  18. Ionization effects in electronic inner-shells of ionized atoms

    International Nuclear Information System (INIS)

    Shchornak, G.

    1983-01-01

    A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

  19. Photoionization effects in ionization fronts

    International Nuclear Information System (INIS)

    Arrayas, Manuel; Fontelos, Marco A; Trueba, Jose L

    2006-01-01

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

  20. Photoionization effects in ionization fronts

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-12-21

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

  1. Ionizing radiation promotes protozoan reproduction

    International Nuclear Information System (INIS)

    Luckey, T.D.

    1986-01-01

    This experiment was performed to determine whether ionizing radiation is essential for maximum growth rate in a ciliated protozoan. When extraneous ionizing radiation was reduced to 0.15 mrad/day, the reproduction rate of Tetrahymena pyriformis was significantly less (P less than 0.01) than it was at near ambient levels, 0.5 or 1.8 mrad/day. Significantly higher growth rates (P less than 0.01) were obtained when chronic radiation was increased. The data suggest that ionizing radiation is essential for optimum reproduction rate in this organism

  2. Nonlinear modulation of ionization waves

    International Nuclear Information System (INIS)

    Bekki, Naoaki

    1981-01-01

    In order to investigate the nonlinear characteristics of ionization waves (moving-striations) in the positive column of glow discharge, a nonlinear modulation of ionization waves in the region of the Pupp critical current is analysed by means of the reductive perturbation method. The modulation of ionization waves is described by a nonlinear Schroedinger type equation. The coefficients of the equation are evaluated using the data of the low pressure Argon-discharge, and the simple solutions (plane wave and envelope soliton type solutions) are presented. Under a certain condition an envelope soliton is propagated through the positive column. (author)

  3. Ionization of liquids

    International Nuclear Information System (INIS)

    Gregg, E.C.; Bakale, G.

    1976-01-01

    Application of pulsed-conductivity techniques to ionization phenomena in liquids has yielded new results on electron transport and electron reactions in nonpolar liquids which we have extrapolated to biological systems to develop a novel model of direct radiation damage to mammalian cells that involves the unsolvated electron as the key reactant. Among these new results are electron attachment rate constants of thirty-five substituted nitrobenzene compounds measured in nonpolar solvents which when combined with product anion lifetimes are correlated with cellular radiosensitization efficiencies. From this study we found that electron attachment rates are dependent upon the electron mobility in the solvents and upon the dipole moment of the electron-accepting nitrobenzene compounds. The model also drawn upon energy-dependent electron attachment rates which we have measured in cryogenic liquids, and we have measured in the same solvents associative detachment rate constants and electron momentum transfer cross sections. In addition to these studies of electronic processes in liquids, we have measured ion mobilities of lecithin and chlorophyll in nonpolar solvents and conclude that these solutes form inverse micelles under certain conditions. Formation of these micelles permits electron transport through the lipid micellar walls and electron attachment to electron-accepting polar solutes inside the lipid vesicles to be studied

  4. Ionization in liquids

    International Nuclear Information System (INIS)

    Bakale, G.

    1990-01-01

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

  5. Comparison analysis on permeability improved effect of single and multi section hydraulic fracturing in deep depth seam%深部煤层单段/多段水力压裂增透效果对比

    Institute of Scientific and Technical Information of China (English)

    张春华; 张勇志; 李江涛; 李腾达

    2017-01-01

    为对比深部煤层钻孔内单段和多段水力压裂增透效果,基于谢桥煤矿待揭8煤层赋存条件,分别建立了单段和多段水力压裂增透模型,运用RFPA2D-Flow软件,模拟分析了水力压裂影响区内煤层水压场、应力场、裂隙场和渗透场特征和规律,并进行了效果验证.结果表明:单段压裂起裂时的煤体孔隙水压为7 MPa,多段压裂起裂时的煤体孔隙水压为16 MPa;煤层起裂后,单段压裂时钻孔中部煤体产生了明显的应力集中,而多段压裂时煤体应力分布虽有起伏但无明显应力集中;单段压裂时裂隙主要在钻孔中部位置向顶底板萌发延伸,有效压裂面积较小,多段压裂时各压裂段均可产生类似的裂隙场,有效压裂面积大;单段压裂时煤体渗透系数最大可达初值的249倍,多段水力压裂时最大可达初值的263倍.与钻孔单段水力压裂工艺相比,多段水力压裂可有效提高钻孔瓦斯抽采效果.%In order to compare the permeability effects of a single section and multi section hvdraulic fracturing in the deep seam boreholes,based on the deposition conditions of the proposed opened No.8 seam in Xieqiao Mine,a single section and multi section hydraulic fracturing and permeability improved models were individually established.A RFPA2D-Flow software was applied to simulate and analyze the features and law of the in-seam water pressure field,stress field,crack field and permeability field within the hydraulic fracturing influence zone and the effect verifications were conducted.The results showed that the pore pressure in the coal mass at the initial fracturing of the single section fracturing was 7 MPa and the pore pressure of the coal mass at the initial fracturing of the multi section fracturing was 16 MPa.When the fracturing operation started in the seam,during the single section fracturing,there was an obvious stress concentration occurred in the borehole middle part of the seam.And when a multi

  6. Physics of partially ionized plasmas

    CERN Document Server

    Krishan, Vinod

    2016-01-01

    Plasma is one of the four fundamental states of matter; the other three being solid, liquid and gas. Several components, such as molecular clouds, diffuse interstellar gas, the solar atmosphere, the Earth's ionosphere and laboratory plasmas, including fusion plasmas, constitute the partially ionized plasmas. This book discusses different aspects of partially ionized plasmas including multi-fluid description, equilibrium and types of waves. The discussion goes on to cover the reionization phase of the universe, along with a brief description of high discharge plasmas, tokomak plasmas and laser plasmas. Various elastic and inelastic collisions amongst the three particle species are also presented. In addition, the author demonstrates the novelty of partially ionized plasmas using many examples; for instance, in partially ionized plasma the magnetic induction is subjected to the ambipolar diffusion and the Hall effect, as well as the usual resistive dissipation. Also included is an observation of kinematic dynam...

  7. Resonance Ionization Laser Ion Sources

    CERN Document Server

    Marsh, B

    2013-01-01

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

  8. Safe use of ionizing radiations

    Energy Technology Data Exchange (ETDEWEB)

    1973-01-01

    Based on the ''Code of Practice for the protection of persons against ionizing radiations arising from medical and dental use'' (CIS 74-423), this handbook shows how hospital staff can avoid exposing themselves and others to these hazards. It is designed particularly for junior and student nurses. Contents: ionizing radiations, their types and characteristics; their uses and dangers; basic principles in their safe use; safe use in practice; explanation of terms.

  9. Biomedical applications of ionizing radiation

    International Nuclear Information System (INIS)

    Rosiak, J.M.; Pietrzak, M.

    1997-01-01

    Application of ionizing radiation for sterilization of medical devices, hygienization of cosmetics products as well as formation of biomaterials have been discussed. The advantages of radiation sterilization over the conventional methods have been indicated. The properties of modern biomaterials, hydrogels as well as some ways of their formation and modification under action of ionizing radiation were presented. Some commercial biomaterials of this kind produced in accordance with original Polish methods by means of radiation technique have been pointed out. (author)

  10. Modeling ionization by helicon waves

    International Nuclear Information System (INIS)

    Degeling, A.W.; Boswell, R.W.

    1997-01-01

    The response of the electron distribution function in one dimension to a traveling wave electric field is modeled for parameters relevant to a low-pressure helicon wave plasma source, and the resulting change in the ionization rate calculated. This is done by calculating the trajectories of individual electrons in a given wave field and assuming no collisions to build up the distribution function as the distance from the antenna is increased. The ionization rate is calculated for argon by considering the ionization cross section and electron flux at a specified position and time relative to the left-hand boundary, where the distribution function is assumed to be Maxwellian and the wave travels to the right. The simulation shows pulses in the ionization rate that move away from the antenna at the phase velocity of the wave, demonstrating the effect of resonant electrons trapped in the wave close-quote s frame of reference. It is found that the ionization rate is highest when the phase velocity of the wave is between 2 and 3x10 6 m/s, where the electrons interacting strongly with the wave (i.e., electrons with velocities inside the wave close-quote s open-quotes trapping widthclose quotes) have initial energies just below the ionization threshold. Results from the model are compared with experimental data and show reasonable qualitative agreement. copyright 1997 American Institute of Physics

  11. Resonance ionization scheme development for europium

    Energy Technology Data Exchange (ETDEWEB)

    Chrysalidis, K., E-mail: katerina.chrysalidis@cern.ch; Goodacre, T. Day; Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Naubereit, P. [Johannes Gutenberg-Universität, Institiut für Physik (Germany); Rothe, S.; Seiffert, C. [CERN (Switzerland); Kron, T.; Wendt, K. [Johannes Gutenberg-Universität, Institiut für Physik (Germany)

    2017-11-15

    Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.

  12. Increased ionization rate in laser enrichment

    International Nuclear Information System (INIS)

    Janes, G.S.; Pike, G.T.

    1977-01-01

    A system employing multiple, upper excitation levels in a technique for isotopically selective ionization to improve the ionization efficiency is described. Laser radiation is employed to excite particles with isotopic selectivity. Excitation is produced to a plurality of excited states below the ionization level with the result of increasing the number of available excited particles for ionization and thereby increasing the ionization cross section for improved system efficiency

  13. Ambient ionization mass spectrometry: A tutorial

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-19

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

  14. Ambient ionization mass spectrometry: A tutorial

    International Nuclear Information System (INIS)

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu; Shiea, Jentaie

    2011-01-01

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

  15. Down syndrome and ionizing radiation.

    Science.gov (United States)

    Verger, P

    1997-12-01

    This review examines the epidemiologic and experimental studies into the possible role ionizing radiation might play in Down Syndrome (trisomy 21). It is prompted by a report of a temporal cluster of cases of this chromosomal disorder observed in West Berlin exactly 9 mo after the radioactive cloud from Chernobyl passed. In approximately 90% of cases, Down Syndrome is due to the nondisjunction of chromosome 21, most often in the oocyte, which may be exposed to ionizing radiation during two separate periods: before the completion of the first meiosis or around the time of ovulation. Most epidemiologic studies into trisomies and exposure to ionizing radiation examine only the first period; the Chernobyl cluster is related to the second. Analysis of these epidemiologic results indicates that the possibility that ionizing radiation might be a risk factor in Down Syndrome cannot be excluded. The experimental results, although sometimes contradictory, demonstrate that irradiation may induce nondisjunction in oogenesis and spermatogenesis; they cannot, however, be easily extrapolated to humans. The weaknesses of epidemiologic studies into the risk factors for Down Syndrome at birth (especially the failure to take into account the trisomy cases leading to spontaneous abortion) are discussed. We envisage the utility and feasibility of new studies, in particular among women exposed to prolonged or repeated artificially-produced ionizing radiation.

  16. Health effects of ionizing radiation

    International Nuclear Information System (INIS)

    Pathak, B.

    1989-12-01

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

  17. Ionization equilibrium in dense plasmas

    International Nuclear Information System (INIS)

    Ying, R.

    1987-01-01

    The average degree of ionization for a strongly coupled plasma is investigated and calculated. Two widely used approaches: the Saha equation method and the Thomas-Fermi (TF) statistical atomic model are adopted to determine the degree of ionization. Both methods are modified in a number of ways to include the strong-coupling effect in the plasma. In the Saha equation approach, the strong-coupling effects are introduced through: (i) a replacement of the Coulomb potential by a screened Debye potential; (ii) adoption of the Planck-Larkin partition function; (iii) description of the electron component by Fermi-Dirac statistics. The calculated degree of ionization exceeds that obtained from the original Saha equation, exhibits a minimum as a function of the density and shows an abrupt phase transition from weakly ionized to a fully ionized state. The zero-temperature TF model for compressed ions and the finite-temperature TF model for ions are investigated for the first time. In order to take into account the strong-coupling effect in a systematic way, a strong-coupling TF model is set up. Favorable results with the relatively simple approximations indicate that the newly established strong-coupling TF model is a more systematic and physically consistent approach

  18. Display of charged ionizing particles

    International Nuclear Information System (INIS)

    Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R.

    2017-10-01

    The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

  19. Technical sheets of ionizing radiations. 2. Non-ionizing radiations

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    The biological effects of different non-ionizing radiations are studied: ultra-violet radiation, visible radiation, infrared radiation, micrometric waves, ultrasonics. In spite of their apparent diversity these radiations are similar in their physico-chemical effects, but in view of their widely varying production methods and types of application each type is considered separately. It is pointed out that no organization resembling the CIPR exists in the field of non-ionizing radiations, the result being a great disparity amongst the different legislations in force [fr

  20. Ionizing energy treatment of poultry

    International Nuclear Information System (INIS)

    Mulder, R.W.A.W.

    1983-01-01

    The application of an ionizing energy treatment to poultry carcasses results in a decrease of the number of potentially pathogenic microorganisms, e.g. Salmonellae. At the same time the refrigerated shelf life of treated poultry products is considerably increased. To achieve these beneficial effects doses ranging from 2.00 to 9.00 kGy are needed, but in poultry doses over 5.00 kGy may cause undesirable side-effects. To asses the microbiological quality of ionizing radiation treated end-products adequate isolation methods should be used to include all sublethally injured microorganisms in the colony counts. The assessment of the required lethality of an ionizing energy treatment is difficult as D 10 (decimal reduction) - values depend greatly on several parameters

  1. Ionization of nitrogen cluster beam

    International Nuclear Information System (INIS)

    Yano, Katsuki; Be, S.H.; Enjoji, Hiroshi; Okamoto, Kosuke

    1975-01-01

    A nitrogen cluster beam (neutral particle intensity of 28.6 mAsub(eq)) is ionized by electron collisions in a Bayard-Alpert gauge type ionizer. The extraction efficiency of about 65% is obtained at an electron current of 10 mA with an energy of 50 eV. The mean cluster size produced at a pressure of 663 Torr and temperature of 77.3 K is 2x10 5 molecules per cluster. By the Coulomb repulsion force, multiply ionized cluster ions are broken up into smaller fragments and the cluster ion size reduces to one-fourth at an electron current of 15 mA. Mean neutral cluster sizes depend strongly on the initial degree of saturation PHI 0 and are 2x10 5 , 7x10 4 and 3x10 4 molecules per cluster at PHI 0 's of 0.87, 0.66 and 0.39, respectively. (auth.)

  2. Spectroscopy of highly ionized atoms

    International Nuclear Information System (INIS)

    Livingston, A.E.

    1987-01-01

    The atomic structure and decay characteristics of excited states in multiply ionized atoms represent a fertile testing ground for atomic calculations ranging from accurate ab initio theory for few-electron systems to practical semi-empirical approaches for many-electron species. Excitation of fast ions by thin foils generally produces the highest ionization stages for heavy ions in laboratory sources. The associated characteristics of spectroscopic purity and high time resolution provide unique capabilities for studying the atomic properties of highly-ionized atoms. This report is limited to a brief discussion of three classes of atomic systems that are experiencing current theoretical and experimental interest: precision structure of helium-like ions, fine structure of doubly-excited states, and lifetimes of metastable states. Specific measurements in each of these types of systems are mentioned, with emphasis on the relation to studies involving slow, highly-charged ions

  3. Prenatal exposition on ionizing radiations

    International Nuclear Information System (INIS)

    2001-01-01

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

  4. Ionization chambers for LET determination

    DEFF Research Database (Denmark)

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

    2010-01-01

    resolution and high sensitivity are necessary. For exact dosimetry which is done using ionization chambers (ICs), the recombination taking place in the IC has to be known. Up to now, recombination is corrected phenomenologically and more practical approaches are currently used. Nevertheless, Jaff´e's theory...... of columnar recombination was designed to model the detector efficiency of an ionization chamber. Here, we have shown that despite the approximations and simplification made, the theory is correct for the LETs typically found in clinical radiotherapy employing particles from protons to carbon ions...

  5. Stimulating effects of ionizing radiation

    International Nuclear Information System (INIS)

    Jaworowski, Z.

    1995-01-01

    The influence of low doses on human organism is not definite known up to now. The worldwide discussion on this topic has been presented. A lot of analysed statistical data proved that the stimulating effect of low doses of ionizing radiation really exists and can have a beneficial influence on human health. 43 refs, 4 figs, 6 tabs

  6. Food irradiation with ionizing radiation

    International Nuclear Information System (INIS)

    Hrudkova, A.; Pohlova, M.; Sedlackova, J.

    1974-01-01

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

  7. Trends in resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Hurst, G.S.

    1986-01-01

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

  8. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multi-photon ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photo-electron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photo-ionization signal. For both ns and np states the ''field induced'' MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength

  9. Resonance ionization spectroscopy in dysprosium

    Energy Technology Data Exchange (ETDEWEB)

    Studer, D., E-mail: dstuder@uni-mainz.de; Dyrauf, P.; Naubereit, P.; Heinke, R.; Wendt, K. [Johannes Gutenberg-Universität Mainz, Institut für Physik (Germany)

    2017-11-15

    We report on resonance ionization spectroscopy (RIS) of high-lying energy levels in dysprosium. We developed efficient excitation schemes and re-determined the first ionization potential (IP) via analysis of Rydberg convergences. For this purpose both two- and three-step excitation ladders were investigated. An overall ionization efficiency of 25(4) % could be demonstrated in the RISIKO mass separator of Mainz University, using a three-step resonance ionization scheme. Moreover, an extensive analysis of the even-parity 6sns- and 6snd-Rydberg-series convergences, measured via two-step excitation was performed. To account for strong perturbations in the observed s-series, the approach of multichannel quantum defect theory (MQDT) was applied. Considering all individual series limits we extracted an IP-value of 47901.76(5) cm{sup −1}, which agrees with the current literature value of 47901.7(6) cm{sup −1}, but is one order of magnitude more precise.

  10. Ionizing radiation accidents. Data interpretation

    International Nuclear Information System (INIS)

    Cascon, Adriana S.

    2003-01-01

    After a general outlook of the biological effects at the cellular and molecular level, the somatic effects of the ionizing radiation are described. Argentine regulations and the ICRP recommendations on radiological protection of professionally exposed workers are also summarized. The paper includes practical advices for the physician that has to take care of an irradiated patient

  11. Atomic and molecular resonance ionization

    International Nuclear Information System (INIS)

    Botter, R.; Petit, A.

    1990-01-01

    Published in summary form only the paper recalls the principle of resonance photoionization, transition probability, selectivity and critical parameters. Examples of applications are briefly treated: Trace analysis by resonance ionization mass spectroscopy for detection of Fe in Zr F 4 for fabrication of optical fibers and laser isotopic separation of U 235 and Gd 157 [fr

  12. Natural sources of ionizing radiations

    International Nuclear Information System (INIS)

    Marej, A.N.

    1984-01-01

    Natural sources of ionizing radiations are described in detail. The sources are subdivided into sources of extraterrestrial origin (cosmic radiation) and sources of terrestrial origin. Data on the concentration of different nuclides in rocks, various soils, ground waters, atmospheric air, tissues of plants and animals, various food stuffs are presented. The content of natural radionuclides in environmental objects, related to human activities, is discussed

  13. Negative chemical ionization mass spectrometry

    International Nuclear Information System (INIS)

    Smit, A.L.C.

    1979-01-01

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

  14. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

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

  15. Biopositive Effects of Ionizing Radiation?

    International Nuclear Information System (INIS)

    Broda, E.

    1972-01-01

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

  16. Ionizing radiations: effects and sources

    International Nuclear Information System (INIS)

    Vignes, S.; Nenot, J.C.

    1978-01-01

    Having first mentioned the effects of ionizing radiations in cancerogenisis, pre-natal, and genetic fields, the authors present the different sources of radiations and estimate their respective contributions to the total irradiation dose. Their paper makes reference to the main elements of a report issued by the United Nations Scientific Committee in 1977 [fr

  17. Ionizing radiations, detection, dosimetry, spectrometry

    International Nuclear Information System (INIS)

    Blanc, D.

    1997-10-01

    A few works in French language are devoted to the detection of radiations. The purpose of this book is to fill a gap.The five first chapters are devoted to the properties of ionizing radiations (x rays, gamma rays, leptons, hadrons, nuclei) and to their interactions with matter. The way of classification of detectors is delicate and is studied in the chapter six. In the chapter seven are studied the statistics laws for counting and the spectrometry of particles is treated. The chapters eight to thirteen study the problems of ionization: charges transport in a gas, ionization chambers (theory of Boag), counters and proportional chambers, counters with 'streamers', chambers with derive, spark detectors, ionization chambers in liquid medium, Geiger-Mueller counters. The use of a luminous signal is the object of the chapters 14 to 16: conversion of a luminous signal in an electric signal, scintillators, use of the Cerenkov radiation. Then, we find the neutron detection with the chapter seventeen and the dosimetry of particles in the chapter eighteen. This book does not pretend to answer to specialists questions but can be useful to physicians, engineers or physics teachers. (N.C.)

  18. On the Saha Ionization Equation

    Indian Academy of Sciences (India)

    Abstract. We revisit the Saha Ionization Equation in order to highlightthe rich interdisciplinary content of the equation thatstraddles distinct areas of spectroscopy, thermodynamics andchemical reactions. In a self-contained discussion, relegatedto an appendix, we delve further into the hidden message ofthe equation in terms ...

  19. A liquid ionization chamber using tetramethylsilane

    International Nuclear Information System (INIS)

    Engler, J.; Keim, H.

    1983-12-01

    First results with a liquid ionization chamber using tetramethylsilane (TMS) are presented. A stack of iron plates was tested with cosmic ray muons and the charge output for minimum ionizing particles was measured. (orig.) [de

  20. UV Ionizer for Neutral Wind Mass Spectrometers

    Data.gov (United States)

    National Aeronautics and Space Administration — Current neutral particle instrumentation relies on hot cathode filaments or an electron gun for ionizing the target medium.  These ionization sources represent a...

  1. Automatic system for evaluation of ionizing field

    International Nuclear Information System (INIS)

    Pimenta, N.L.; Calil, S.J.

    1992-01-01

    A three-dimensional cartesian manipulator for evaluating the ionizing field and able to position a ionization chamber in any point of the space is developed. The control system is made using a IBM microcomputer. The system aimed the study of isodose curves from ionizing sources, verifying the performance of radiotherapeutic equipment. (C.G.C.)

  2. Progress on untargeted effects of ionizing irradiation

    International Nuclear Information System (INIS)

    Liu Jing; Chen Jihong; Li Wenjian

    2010-01-01

    The side effect of ionizing irradiation has been paid more attention with its widely using in tumor treating and mutation breeding. In recent years, untargeted effects induced by ionizing irradiation have become a hotspot of radiobiology. Here, according to reported results, we reviewed the types (genomic instability, bystander effect and adaptive response) and mechanisms of untargeted effects of ionizing irradiation in this paper. (authors)

  3. 29 CFR 1926.53 - Ionizing radiation.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Ionizing radiation. 1926.53 Section 1926.53 Labor... § 1926.53 Ionizing radiation. (a) In construction and related activities involving the use of sources of ionizing radiation, the pertinent provisions of the Nuclear Regulatory Commission's Standards for...

  4. 29 CFR 1910.1096 - Ionizing radiation.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 6 2010-07-01 2010-07-01 false Ionizing radiation. 1910.1096 Section 1910.1096 Labor... Ionizing radiation. (a) Definitions applicable to this section. (1) Radiation includes alpha rays, beta... the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the...

  5. Ionizing radiation sources. Ionizing radiation interaction with matter

    International Nuclear Information System (INIS)

    Popits, R.

    1976-01-01

    Fundamentals of nuclear physics are reviewed under the headings: obtaining of X-rays and their properties; modes of radioactive decay of natural or man-made radionuclides; radioactive neutron sources; nuclear fission as basis for devising nuclear reactors and weapons; thermonuclear reactions; cosmic radiation. Basic aspects of ionizing radiation interactions with matter are considered with regard to charged particles, photon radiation, and neutrons. (A.B.)

  6. Electron-Impact Ionization and Dissociative Ionization of Biomolecules

    Science.gov (United States)

    Huo, Winifred M.; Chaban, Galina M.; Dateo, Christopher E.

    2006-01-01

    It is well recognized that secondary electrons play an important role in radiation damage to humans. Particularly important is the damage of DNA by electrons, potentially leading to mutagenesis. Molecular-level study of electron interaction with DNA provides information on the damage pathways and dominant mechanisms. Our study of electron-impact ionization of DNA fragments uses the improved binary-encounter dipole model and covers DNA bases, sugar phosphate backbone, and nucleotides. An additivity principle is observed. For example, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3(sup prime)- and C5 (sup prime)-deoxyribose-phospate cross sections, differing by less than 5%. Investigation of tandem double lesion initiated by electron-impact dissociative ionization of guanine, followed by proton reaction with the cytosine in the Watson-Crick pair, is currently being studied to see if tandem double lesion can be initiated by electron impact. Up to now only OH-induced tandem double lesion has been studied.

  7. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    International Nuclear Information System (INIS)

    TROYER, G.L.

    2000-01-01

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% (at) 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse rise time versus photo peak position and resolution. These data were collected to investigate the effect of pulse rise time compensation on resolution and efficiency

  8. A simple Bragg detector design for AMS and IBA applications

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Arnold Milenko; Döbeli, Max; Seiler, Martin; Synal, Hans-Arno

    2015-08-01

    A new compact Bragg type gas ionization chamber (GIC) has been built for use as particle counter in AMS and IBA applications. The detector stands out due to its simple concept, which does not include a Frisch grid. Test experiments have been performed with ions in the mass range from He to Th and energies ranging from 30 keV to 2.5 MeV, in order to find optimal measurement conditions and to characterize the detector performance. For projectiles heavier than Al at energies below 2.5 MeV the obtained energy resolution is comparable with that of a state-of-the-art GIC with Frisch grid and clearly outperforms solid state detectors. Additionally the operation of this simplified Bragg GIC in the electron multiplication mode was investigated for the first time, which allows the detection of radiocarbon ions at energies below 50 keV with an energy resolution of the order of 10 keV.

  9. Cell fusion by ionizing radiation

    International Nuclear Information System (INIS)

    Khair, M.B.

    1993-08-01

    The relevance and importance of cell fusion are illustrated by the notion that current interest in this phenomenon is shared by scientists in quite varied disciplines. The diversity of cellular membrane fusion phenomena could provoke one to think that there must be a multitude of mechanisms that can account for such diversity. But, in general, the mechanism for the fusion reaction itself could be very similar in many, or even all, cases. Cell fusion can be induced by several factors such as virus Sendai, polyethylene glycol, electric current and ionizing radiation. This article provides the reader with short view of recent progress in research on cell fusion and gives some explanations about fusion mechanisms. This study shows for the first time, the results of the cell fusion induced by ionizing radiations that we have obtained in our researches and the work performed by other groups. (author). 44 refs

  10. Laser ionization of molecular clusters

    International Nuclear Information System (INIS)

    Desai, S.; Feigerle, C.S.

    1995-01-01

    Multiphoton ionization coupled with mass spectrometry was used to investigate molecular cluster distributions. Three examples will be discussed in this presentation. First, in studies of neat nitric oxide clusters, (NO) m , an interesting odd-even intensity alternation was observed and will be discussed in terms of electron-pairing considerations. In a separate study, the binary clusters comprising nitric oxide and methane preferentially form a stoichiometric cluster made up of repeating units of (NO) 2 CH 4 . These presumably represent a particularly strongly bound open-quotes van der Waalsclose quotes subunit. Finally, in similar studies of neat carbon disulfide clusters, (CS 2 ) m , additional photon absorption after the two-photon ionization step stimulates a series of intracluster ion-molecular reactions leading to formation of S m + and (CS) m + polymers, as well as intermediate species such as S m + (CS 2 ). This molecular cluster analogue of open-quotes laser snowclose quotes will be described in detail

  11. Health effects of ionizing radiation

    International Nuclear Information System (INIS)

    Radford, E.P.

    1980-01-01

    This presentation is restricted to the health effects of low doses of ionizing radiation. In general, these cumulative exposures are well below 100 rem, or about 50 times background or less. The two effects of interest in this dose range are genetic mutations and cancer production. The genetic effects will not be discussed in detail. The chief reason for the rise in risk estimates for cancer is the longer follow-up of exposed populations

  12. Ionizing radiation perception by insects

    International Nuclear Information System (INIS)

    Campanhola, C.

    1980-04-01

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

  13. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Experiments with small animals, tissue cultures, and inanimate materials help with understanding the effects of ionizing radiation that occur at the molecular level and cause the gross effects observed in man. Topics covered in this chapter include the following: Radiolysis of Water; Radiolysis of Organic Compounds; Radiolysis in Cells; Radiation Exposure and Dose Units; Dose Response Curves; Radiation Effects in Animals; Factors Affecting Health Risks. 8 refs., 3 figs., 5 tabs

  14. Risks Associated with Ionizing Radiations

    International Nuclear Information System (INIS)

    Cascon, Adriana

    2009-01-01

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

  15. The dosimetry of ionizing radiation

    CERN Document Server

    1990-01-01

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

  16. Ionization of H Rydberg atoms

    International Nuclear Information System (INIS)

    Hillermier, C.F.; Bluemental, R.; Smilansky, U.

    1991-07-01

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

  17. Ionizing radiation and cancer prevention

    International Nuclear Information System (INIS)

    Hoel, D.G.

    1995-01-01

    Ionizing radiation long has been recognized as a cause of cancer. Among environmental cancer risks, radiation in unique in the variety of organs and tissues that it can affect. Numerous epidemiological studies with good dosimetry provide the basis for cancer risk estimation, including quantitative information derived from observed dose-response relationships. The amount of cancer attributable to ionizing radiation is difficult to estimate, but numbers such as 1 to 3% have been suggested. Some radiation-induced cancers attributable to ionizing radiation is difficult to estimate, but numbers such as 1 to 3% have been suggested. Some radiation-induced cancers attributable to naturally occurring exposures, such as cosmic and terrestrial radiation, are not preventable. The major natural radiation exposure, radon, can often be reduced, especially in the home, but not entirely eliminated. Medical use of radiation constitutes the other main category of exposure, radon, can often be reduced, especially in the home, but not entirely eliminated. Medical use of radiation constitutes the other main category of exposure; because of the importance of its benefits to one's health, the appropriate prevention strategy is to simply work to minimize exposures. 9 refs., 1 fig., 5 tabs

  18. Loss of ions in cavity ionization chambers

    International Nuclear Information System (INIS)

    Takata, N.; Tran, N.T.; Kim, E.; Marsoem, P.; Kurosawa, T.; Koyama, Y.

    2005-01-01

    Ion losses due to initial recombination, volume recombination, and back diffusion were each determined by measurements and calculations for different size cylindrical ionization chambers and spherical ionization chambers. By measuring signal currents from these ionization chambers irradiated with 60 Co gamma rays, two groups of ion losses were obtained. (Group 1) Ion loss due to initial recombination and diffusion, which changes proportionally to the inverse of the voltage applied to the ionization chambers; (and group 2) ion loss due to volume recombination, which changes proportionally to the inverse of the square of the applied voltage. The diffusion loss was obtained separately by computing electric field distributions in the ionization chambers. It was found that diffusion loss is larger than initial recombination loss for the cylindrical ionization chambers and vise versa for the spherical ionization chambers

  19. On the ionization of interstellar magnesium

    International Nuclear Information System (INIS)

    Gurzadyan, G.A.

    1977-01-01

    It has been shown that two concentric ionization zones of interstellar magnesium must exist around each star: internal, with a radius coinciding with that of the zone of hydrogen ionization Ssub(H); and external, with a radius greater than Ssub(H), by one order. Unlike interstellar hydrogen, interstellar magnesium is ionized throughout the Galaxy. It also transpires that the ionizing radiation of ordinary hot stars cannot provide for the observed high degree of ionization of interstellar magnesium. The discrepance can be eliminated by assuming the existence of circumstellar clouds or additional ionization sources of interstellar magnesium (X-ray background radiation, high-energy particles, etc.). Stars of the B5 and BO class play the main role in the formation of ionization zones of interstellar magnesium; the contribution of O class stars is negligible (<1%). (Auth.)

  20. Hygienic regulation of ionizing radiations

    International Nuclear Information System (INIS)

    Saurov, M.M.

    1984-01-01

    Modern state of the problem on hygienic regulation of ionizing radiations is considered. Concepts and principles of the regulation based on risk concept are presented according to ICRP 26 and 27. Two types of risk are designated: ''absolute'' and ''relative'' ones. The concept of acceptable risk on the basis of cost - benefit ratio is substantiated. Special attention is paid to the principle of accounting the complex of health signs, when determining radiation hazard. To determine the level of permissible risk and permissible dose to population the concept of ''inadmissibility of s-tatistically significant risk'' has been developed. Standards, regulating population doses in the USSR, which are valid nowadays, are considered

  1. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Heribanova, A.

    1995-01-01

    The basic principles and pathways of effects of ionizing radiation on living organisms and cells are outlined. The following topics are covered: effects of radiation on living matter (direct effects, radical or indirect effects, dual radiation action, and molecular biological theories); effects of radiation on cells and tissues (cell depletion, changes in the cytogenetic information, reparation mechanisms), dose-response relationship (deterministic effects, stochastic effects), and the effects of radiation on man (acute radiation sickness, acute local changes, fetus injuries, non-tumorous late injuries, malignant tumors, genetic changes). (P.A.). 3 tabs., 2 figs., 5 refs

  2. XUV ionization of aligned molecules

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

  3. XUV ionization of aligned molecules

    International Nuclear Information System (INIS)

    Kelkensberg, F.; Siu, W.; Gademann, G.; Rouzee, A.; Vrakking, M. J. J.; Johnsson, P.; Lucchini, M.; Lucchese, R. R.

    2011-01-01

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

  4. Space Flight Ionizing Radiation Environments

    Science.gov (United States)

    Koontz, Steve

    2017-01-01

    The space-flight ionizing radiation (IR) environment is dominated by very high-kinetic energy-charged particles with relatively smaller contributions from X-rays and gamma rays. The Earth's surface IR environment is not dominated by the natural radioisotope decay processes. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of space radiation environments, beginning with the space radiation environment on the International Space Station and moving outward through the Van Allen belts to cislunar space. The benefits and limitations of radiation shielding materials will also be summarized.

  5. Advanced Thin Ionization Calorimeter (ATIC)

    Science.gov (United States)

    Wefel, John P.

    1998-01-01

    This is the final report for NASA grant NAGW-4577, "Advanced Thin Ionization Calorimeter (ATIC)". This grant covered a joint project between LSU and the University of Maryland for a Concept Study of a new type of fully active calorimeter to be used to measure the energy spectra of very high energy cosmic rays, particularly Hydrogen and Helium, to beyond 1014 eV. This very high energy region has been studied with emulsion chamber techniques, but never investigated with electronic calorimeters. Technology had advanced to the point that a fully active calorimeter based upon Bismuth Germanate (BGO) scintillating crystals appeared feasible for balloon flight (and eventually space) experiments.

  6. Effects of ionizing radiation on vitamins

    International Nuclear Information System (INIS)

    Thayer, D.W.; Fox, J.B. Jr.; Lakritz, L.

    1991-01-01

    Vitamins are known to be sensitive to the effects of ionizing radiation. Since most foods contain a large proportion of water, the most probable reaction of the ionizing radiation would be with water; and as vitamins are present in very small amounts compared with other substances in the food they will be affected indirectly by the radiation. This chapter discusses the effect of ionizing radiation on water soluble vitamins and fat soluble vitamins. (author)

  7. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Gisone, Pablo; Perez, Maria R.

    2001-01-01

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

  8. Chemical protection against ionizing radiation

    International Nuclear Information System (INIS)

    Livesey, J.C.; Reed, D.J.

    1987-01-01

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

  9. NMR Metabolomics in Ionizing Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Z.; Xiao, Xiongjie; Hu, Mary Y.

    2016-09-08

    Ionizing radiation is an invisible threat that cannot be seen, touched or smelled and exist either as particles or waves. Particle radiation can take the form of alpha, beta or neutrons, as well as high energy space particle radiation such as high energy iron, carbon and proton radiation, etc. (1) Non-particle radiation includes gamma- and x-rays. Publically, there is a growing concern about the adverse health effects due to ionizing radiation mainly because of the following facts. (a) The X-ray diagnostic images are taken routinely on patients. Even though the overall dosage from a single X-ray image such as a chest X-ray scan or a CT scan, also called X-ray computed tomography (X-ray CT), is low, repeated usage can cause serious health consequences, in particular with the possibility of developing cancer (2, 3). (b) Human space exploration has gone beyond moon and is planning to send human to the orbit of Mars by the mid-2030s. And a landing on Mars will follow.

  10. Ionizing radiations in food industry

    International Nuclear Information System (INIS)

    Adamo, M.; Tata, A.

    1999-01-01

    Foodstuffs treatment by ionization is able to produce both a shelf-life extension and/or a food borne diseases control through the pathogenic population reduction/elimination. The main process goal is to ensure the hygienic quality and the wholesomeness of products to be marketed, in order to limit food borne diseases originated mainly through the cross contamination process. In fact several products may contain pathogenic agents or bacteria (e.g. Salmonella and Campylbacter in poultry meat), whose associated pathologies are world-wide increasing. At present, over 40 countries provide clearances for the treatment of about 45 different types of foodstuffs and in over 20 of them the ionizing process is already industrially utilized for spices, poultry, shrimps and vegetables. As it refers to process economic aspects, market researches have shown cost figures ranging from few tens to some hundreds Lit/kg, depending on the dose to products. The costs are competitive with alternative treatments, beyond the recovery of economic productivity reduction caused by food borne diseases

  11. Epigenetic effects of ionizing radiation

    International Nuclear Information System (INIS)

    EI-Naggar, A.M.

    2007-01-01

    Data generated during the last three decades provide evidence of Epigenetic Effects that ave-induced by ionizing radiation, particularly those of high LET values, and low level dose exposures. Epigenesist is defined as the stepwise process by which genetic information, as modified by environmental influences, is translated into the substance and behavior of cells, tissues, organism.The epigenetic effects cited in the literature are essentially classified into fine types depending on the type and nature of the effect induced.The most accepted postulation, for the occurrence of these epigenetic effects, is a radiation induced bio electric disturbances in the environment of the non-irradiated cellular volume. This will trigger signals that will induce effects in the unirradiated cells.The epigenetic effects referenced in the literature up to date are five types; namely, Genomic Instability, Bystander. Effects, Clastogenic Plasma Factors,, Abscopal Effects, and Tran generational Effects.The demonstration of Epigenetic Effects associated with exposure to ionizing radiation indicates the need to re- examine the concept of radiation dose and target size. Also an improved understanding of qualifiring and quantifying radiation risk estimates may be attained. Also, a more logical means to understand the underlying mechanisms of radiation induced carcinogenic transformation of cells

  12. K-shell ionization by antiprotons

    International Nuclear Information System (INIS)

    Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

    1987-01-01

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

  13. Regulatory control of ionizing radiations in Ecuador

    International Nuclear Information System (INIS)

    Benitez, Manuel

    1996-03-01

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

  14. Ionization probes of molecular structure and chemistry

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  15. Ionization versus indirect effects of ionizing radiation on cellular DNA

    International Nuclear Information System (INIS)

    Cadet, Jean; Ravanat, Jean-Luc; Douki, Thierry

    2012-01-01

    Emphasis has been placed in the last decade on the elucidation of the main degradation pathways of isolated DNA mediated by hydroxyl radical (OH) and one-electron oxidation reactions as the result of indirect and direct effects of ionizing radiation respectively. This has led to the isolation and characterization of about 100 oxidized purine and pyrimidine nucleosides if hydroperoxide precursors and diastereomers are included. However, far less information is available on the mechanisms of radiation-induced degradation of bases in cellular DNA mostly due partly to analytical difficulties. It may be reminded that the measurement of oxidized nucleosides and bases in nuclear DNA is still a challenging issue which until recently has been hampered by the use of inappropriate methods such as the GC-MS that have led to overestimated values of the lesions by factors varying between two and three orders of magnitude. At the present, using the accurate and sensitive HPLC/MS/MS assay, 11 single modified nucleosides and bases were found to be generated in cellular DNA upon exposure to gamma rays and heavy ions. This validates several of the OH-mediated oxidation pathways of thymine, guanine and adenine that were previously inferred from model studies. The concomitant decrease in the yields of oxidized bases with the increase in the LET of heavy ions is accounted for by the preponderance of indirect effects in the damaging action of ionizing radiation on DNA. Further evidence for the major role played by .OH was provided by the results of exposure of cells to high intensity 266 nm laser pulses. Under these conditions 8-oxo-7,8-dihydroguanine is mostly produced by biphotonic ionization of DNA nucleobases and subsequent hole migration to guanine bases. It is likely that some of the oxidized bases that have been isolated as single lesions are in fact involved in clustered damage. Interestingly it was recently shown that a single oxidation hit is capable of generating complex

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

    International Nuclear Information System (INIS)

    Matsuzawa, Takao; Otsubo, Tomonobu; Ikke, Satoshi; Taguchi, Noriko; Takeda, Rie

    2005-01-01

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

  17. Heating and ionization in MHD shock waves propagating into partially ionized plasma

    International Nuclear Information System (INIS)

    Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

    1975-09-01

    A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

  18. Electron ionization and the Compton effect in double ionization of helium

    International Nuclear Information System (INIS)

    Samson, J.

    1994-01-01

    The author discusses ionization phenomena in helium, both photoionization and electron ionization. In particular he compares double ionization cross sections with total cross sections, as a function of electron energy, and photon energy. Data is discussed over the energy range up to 10 keV

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

    International Nuclear Information System (INIS)

    Stoyanov, D G

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-08-15

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

  1. Heating and ionization in MHD shock wave propagating into partially ionized plasma

    International Nuclear Information System (INIS)

    Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

    1975-09-01

    A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

  2. Social trust and ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Meadd, E. [Faculty of Environmental Studies, York University, Toronto, Ontario (Canada)

    2002-07-01

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

  3. Social trust and ionizing radiation

    International Nuclear Information System (INIS)

    Meadd, E.

    2002-01-01

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

  4. Ionization efficiency calculations for cavity thermoionization ion source

    International Nuclear Information System (INIS)

    Turek, M.; Pyszniak, K.; Drozdziel, A.; Sielanko, J.; Maczka, D.; Yuskevich, Yu.V.; Vaganov, Yu.A.

    2009-01-01

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

  5. Ionizing radiation and water reuse

    International Nuclear Information System (INIS)

    Borrely, Sueli Ivone; Sampa, Maria Helena de Oliveira; Oikawa, Hiroshi; Silveira, Carlos Gaia da; Duarte, Celina Lopes; Cherbakian, Eloisa Helena

    2002-01-01

    The aim of the present paper is to point out the possibility of including ionizing radiation for wastewater treatment and reuse. Radiation processing is an efficient technology which can be useful for water reuse once the process can reduce not only the biological contamination but also organic substances, promoting an important acute toxicity removal from aquatic resources. Final secondary effluents from three different wastewater treatment plant were submitted to electron beam radiation and the process efficacy was evaluated. Concerning disinfection, relatively low radiation doses (2,0 - 4,0 kGy) accounted for 4 to 6 cycle log reduction for total coliforms. When radiation was applied for general wastewater improvement related to the chemical contamination, radiation process reduced from 78% up to 100% the total acute toxicity, measured for crustaceans, D. similis, and for V. fiscehri bacteria. (author)

  6. Ionization cooling ring for muons

    Directory of Open Access Journals (Sweden)

    R. Palmer

    2005-06-01

    Full Text Available Practical ionization cooling rings could lead to lower cost or improved performance in neutrino factory or muon collider designs. The ring modeled here uses realistic three-dimensional fields. The performance of the ring compares favorably with the linear cooling channel used in the second U.S. Neutrino Factory Study. The normalized 6D emittance of an ideal ring is decreased by a factor of approximately 240, compared with a factor of only 15 for the linear channel. We also examine such real-world effects as windows on the absorbers and rf cavities and leaving empty lattice cells for injection and extraction. For realistic conditions the ring decreases the normalized 6D emittance by a factor of 49.

  7. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... barriers, an ability classical particles do not possess. Tunnelling is a fundamental quantum mechanical process, a process that is distinctly non-classical, so solving this tunnelling problem is not only relevant for molecular physics, but also for quantum theory in general. In this dissertation the theory...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  8. Device for detecting ionizing radiation

    International Nuclear Information System (INIS)

    Anatychuk, L.I.; Kharitonov, J.P.; Kusniruk, V.F.; Meir, V.A.; Melnik, A.P.; Ponomarev, V.S.; Skakodub, V.A.; Sokolov, A.D.; Subbotin, V.G.; Zhukovsky, A.N.

    1980-01-01

    The present invention relates to ionizing radiation sensors, and , more particularly, to semiconductor spectrometers with thermoelectric cooling, and can most advantageously be used in mineral raw material exploration and evaluation under field conditions. The spectrometer comprises a vacuum chamber with an entrance window for passing the radiation therethrough. The vacuum chamber accommodates a thermoelectric cooler formed by a set of peltier elements. A heat conducting plate is mounted on the cold side of the thermoelectric cooler, and its hot side is provided with a radiator. Mounted on the heat conducting plate are sets of peltier elements, integral with the thermoelectric cooler and independent of one another. The peltier elements of these sets are stacked so as to develop the minimum temperature conditions on one set carrying a semiconductor detector and to provide the maximum refrigeration capacity conditions on the other set provided with the field-effect transistor mounted thereon

  9. Sodium ionization detector and sensor

    International Nuclear Information System (INIS)

    Hrizo, J.; Bauerle, J.E.

    1979-01-01

    Work conducted on a basic technology development effort with the Westinghouse Sodium Ionization Detector (SID) sensor is reported. Included are results obtained for three task areas: (1) On-line operational response testing - in-situ calibration techniques; (2) Performance-reliability characteristics of aged filaments; and (3) Evaluation of chemical interference effects. The results showed that a calibrator filament coated with a sodium compound, when activated, does supply the necessary sodium atoms to provide a valid operational in-situ test. The life time of new Cr 2 0 3 -protected SID sensor filaments can be extended by operating at a reduced temperature. However, there also is a reduction in the sensitivity. Non-sodium species, such as products from a smoldering fire and organic aerosols, produce an interference response from the sensor comparable to a typical sodium response

  10. Ionization by a pulsed plasma surface water

    International Nuclear Information System (INIS)

    Bloyet, E.; Leprince, P.; Marec, J.; Llamas Blasco, M.

    1981-01-01

    The ionization mechanism is studied of a pulsed surface wave generating a microwave discharge. When the plasma is dominated by collisions, it is found that the velocity of the ionization front depends on the ponderomotive force due to the field gradient in the front. (orig.)

  11. An ionization chamber with magnetic levitated electrodes

    CERN Document Server

    Kawaguchi, T

    1999-01-01

    A new type of ionization chamber which has magnetically levitated electrodes has been developed. The electrodes are supplied voltages for the repelling of ions by a battery which is also levitated with the electrodes. The characteristics of this ionization chamber are investigated in this paper.

  12. Basic symbol for ionizing radiations (second revision)

    International Nuclear Information System (INIS)

    1992-01-01

    Includes a detailed description of basic symbol for ionizing radiations to be used to prevent about the presence, or possibility of presence, of ionizing radiations (X-ray, gamma radiation, particles, electrons, neutrons and protons), as well as to identify radioactive devices and materials

  13. Gas ionization by focused laser beams

    International Nuclear Information System (INIS)

    Brito, A.L. de.

    1984-01-01

    It is shown that the effect of line broadening by focusing may considerably contribute to the observed laser-induced ionization of gases when the ionization energy of the gas molecules is well above the mean photon energy of the laser radiation. (Author) [pt

  14. A Versatile Integrated Ambient Ionization Source Platform

    Science.gov (United States)

    Ai, Wanpeng; Nie, Honggang; Song, Shiyao; Liu, Xiaoyun; Bai, Yu; Liu, Huwei

    2018-04-01

    The pursuit of high-throughput sample analysis from complex matrix demands development of multiple ionization techniques with complementary specialties. A versatile integrated ambient ionization source (iAmIS) platform is proposed in this work, based on the idea of integrating multiple functions, enhancing the efficiency of current ionization techniques, extending the applications, and decreasing the cost of the instrument. The design of the iAmIS platform combines flowing atmospheric pressure afterglow (FAPA) source/direct analysis in real time (DART), dielectric barrier discharge ionization (DBDI)/low-temperature plasma (LTP), desorption electrospray ionization (DESI), and laser desorption (LD) technique. All individual and combined ionization modes can be easily attained by modulating parameters. In particular, the FAPA/DART&DESI mode can realize the detection of polar and nonpolar compounds at the same time with two different ionization mechanisms: proton transfer and charge transfer. The introduction of LD contributes to the mass spectrometry imaging and the surface-assisted laser desorption (SALDI) under ambient condition. Compared with other individual or multi-mode ion source, the iAmIS platform provides the flexibility of choosing different ionization modes, broadens the scope of the analyte detection, and facilitates the analysis of complex samples. [Figure not available: see fulltext.

  15. Neutron accelerator tube having improved ionization section

    International Nuclear Information System (INIS)

    Givens, W.W.

    1982-01-01

    A neutron accelerator tube is described having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least one cathode member located in the tube adjacent to th replenisher section may have a protuberant portion extending axially into the ionization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

  16. Bystander Effects of Ionizing Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B. [Harvard T.H. Chan School of Public Health, Boston, MA (United States). Dept. of Genetics and Complex Diseases

    2017-01-17

    The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

  17. Bystander Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    Little, John B.

    2017-01-01

    The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

  18. Non-Ionizing Radiation Used in Microwave Ovens

    Science.gov (United States)

    ... Non-Ionizing Radiation Used in Microwave Ovens Non-Ionizing Radiation Used in Microwave Ovens Explore the interactive, virtual ... can do Where to learn more About Non-Ionizing Radiation Used in Microwave Ovens Microwave Oven. Microwave ovens ...

  19. Experimental comparison of models for ultrafast impact ionization is silicon

    DEFF Research Database (Denmark)

    Tarekegne, Abebe Tilahun; Iwaszczuk, Krzysztof; Jepsen, Peter Uhd

    2016-01-01

    We compare experimentally the exponential and quadratic (Keldysh formula) impact ionization models using THz induced impact ionization in silicon. We demonstrate that the exponential model offers the best description of impact ionization process for ultrashort electric filed pulses.......We compare experimentally the exponential and quadratic (Keldysh formula) impact ionization models using THz induced impact ionization in silicon. We demonstrate that the exponential model offers the best description of impact ionization process for ultrashort electric filed pulses....

  20. Ionization Cooling using Parametric Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland P.

    2008-06-07

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

  1. Ionization Cooling using Parametric Resonances

    International Nuclear Information System (INIS)

    Johnson, Rolland P.

    2008-01-01

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

  2. Laser-induced ionization of Na vapor

    International Nuclear Information System (INIS)

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

  3. Neutron accelerator tube having improved ionization section

    International Nuclear Information System (INIS)

    Givens, W.W.

    1981-01-01

    A neutron accelerator tube having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emmission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least 2. One cathode member located in the tube adjacent to the replenisher section may have a protuberant portion extending axially into the ioization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

  4. Regulation on protection against ionizing radiations

    International Nuclear Information System (INIS)

    1995-01-01

    This regulation has as the objective to establish the criteria tending toward protecting the health of the population of the radiologic risks that can be derive from the employment of the ionizing radiations and similar activities. It establishes the requirements to comply with the radiactive installations, equipment transmitters of ionizing radiations, personal that works in them, operate the equipment and carry out any another similar activity such as: production, importation, exportation, transportation, transference of radioactive material or equipment generators of radiations ionizing. (S. Grainger) [es

  5. Effects of ionizing radiation on life

    International Nuclear Information System (INIS)

    Rausch, L.

    1982-01-01

    Radiobiology in the last years was able to find detailed explanations for the effects of ionizing radiation on living organisms. But it is still impossible to make exact statements concerning the damages by radiation. Even now, science has to content itself with probability data. Moreover no typical damages of ionizing radiation can be identified. Therefore, the risks of ionizing radiation can only be determined by comparison with the spontaneous rate of cancerous or genetic defects. The article describes the interaction of high-energy radiation with the molecules of the organism and their consequences for radiation protection. (orig.)

  6. Ionization of atoms by bare ion projectiles

    International Nuclear Information System (INIS)

    Tribedi, L.C.

    1997-01-01

    The double differential cross sections (DDCS) for low energy electron emission can provide stringent tests to the theoretical models for ionization in ion-atom collision. The two-center effects and the post collision interactions play a major role in ionization by highly charged, high Z projectiles. We close-quote ll review the recent developments in this field and describe our efforts to study the energy and angular distributions of the low energy electrons emitted in ion-atom ionization. copyright 1997 American Institute of Physics

  7. Radionuclide measurements using resonantly enhanced collisional ionization

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1987-01-01

    This report describes development of a laser-enhanced collisional ionization method for direct radionuclide measurements that are independent of radioactive decay. The technique uses two nitrogen-laser-pumped dye lasers to selectively excite the target isotope to an electronic state near the ionization threshold. The excited actinide atoms then undergo collisions with a buffer gas and are efficiently ionized. The resulting ions can be detected by conventional methods. The attributes of this approach include highly sensitive isotope analysis with relatively inexpensive lasers and a simple vacuum system. 9 refs., 3 figs

  8. Leukemia and ionizing radiation revisited

    Energy Technology Data Exchange (ETDEWEB)

    Cuttler, J.M. [Cuttler & Associates Inc., Vaughan, Ontario (Canada); Welsh, J.S. [Loyola University-Chicago, Dept. or Radiation Oncology, Stritch School of Medicine, Maywood, Illinois (United States)

    2016-03-15

    A world-wide radiation health scare was created in the late 19508 to stop the testing of atomic bombs and block the development of nuclear energy. In spite of the large amount of evidence that contradicts the cancer predictions, this fear continues. It impairs the use of low radiation doses in medical diagnostic imaging and radiation therapy. This brief article revisits the second of two key studies, which revolutionized radiation protection, and identifies a serious error that was missed. This error in analyzing the leukemia incidence among the 195,000 survivors, in the combined exposed populations of Hiroshima and Nagasaki, invalidates use of the LNT model for assessing the risk of cancer from ionizing radiation. The threshold acute dose for radiation-induced leukemia, based on about 96,800 humans, is identified to be about 50 rem, or 0.5 Sv. It is reasonable to expect that the thresholds for other cancer types are higher than this level. No predictions or hints of excess cancer risk (or any other health risk) should be made for an acute exposure below this value until there is scientific evidence to support the LNT hypothesis. (author)

  9. Exposure to non ionizing radiations

    International Nuclear Information System (INIS)

    Campanella, L.; Dragone, R.; Pastorelli, A.

    2001-01-01

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

  10. Neutron-sensitive ionization chamber

    International Nuclear Information System (INIS)

    Mayer, W.

    1978-01-01

    The neutron-sensitive ionization chamber which is to be applied for BWRs consists of a cylindrical outer electrode, closed at the ends, and a concentrically arranged inner electrode. It is designed as a hollow tube and coated with uranium on the outside. The reaction space lies between the two electrodes. The electrical connection is obtained through a coaxial cable whose nickel helix is properly intorduced into the inner electrode made of titanium or nickel. The sheathing respectively external conductor of the cable has got the same diameter as the outer electrode and is butt-welded to it. Between the cable helix and the sheathing there is filled Al 2 O 3 powder. The reaction space is sealed against the cable by means of a little tube pushed over the internal conductor resp. the helix. It consists of Ni resp. Al 2 O 3 which is coated on the outside at first by a layer of Al 2 O 3 and a layer of Ni resp. by a metal layer on the inside and on the outside. (DG) [de

  11. Ionizing radiation and thyroid cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hall, P. (Karolinska Inst., Stockholm (Sweden). Inst. of Environmental Medicine); Holm, L.E. (Swedish Radiation Protection Inst., Stockholm (Sweden))

    1994-01-01

    Epidemiological studies provide the primary data source on cancer risk in man after exposure to ionizing radiation. The present paper discusses methodological difficulties in epidemiological studies and reviews current epidemiological knowledge on radiation-induced thyroid cancer. Most studies of radiation-induced cancer are of a ''historical observational'' type and are also non-experimental in design. Seldom is there an opportunity to consider other factors playing on cancer risk. Since many of the study subjects were exposed a long time ago there could also be difficulties in calculating the radiation doses, and to identify and follow the exposed subjects. Short exposure to low doses of gamma radiation can induce thyroid cancer in children, whereas a relationship between protracted low-dose exposure and thyroid cancer has not been established so far. The most important future issues concerning radiation-induced thyroid cancer are the risks following low radiation doses and/or protracted radiation exposure and cancer risks after [sup 131]I exposure in childhood. (authors). 35 refs., 3 tabs.

  12. Biological Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    Durand, J.L.

    2000-01-01

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

  13. Sterilizing insects with ionizing radiation

    International Nuclear Information System (INIS)

    Bakri, A.; Mehta, K.; Lance, D.R.

    2005-01-01

    Exposure to ionizing radiation is currently the method of choice for rendering insects reproductively sterile for area-wide integrated pest management (AW-IPM) programmes that integrate the sterile insect technique (SIT). Gamma radiation from isotopic sources (cobalt-60 or caesium-137) is most often used, but high-energy electrons and X-rays are other practical options. Insect irradiation is safe and reliable when established safety and quality-assurance guidelines are followed. The key processing parameter is absorbed dose, which must be tightly controlled to ensure that treated insects are sufficiently sterile in their reproductive cells and yet able to compete for mates with wild insects. To that end, accurate dosimetry (measurement of absorbed dose) is critical. Irradiation data generated since the 1950s, covering over 300 arthropod species, indicate that the dose needed for sterilization of arthropods varies from less than 5 Gy for blaberid cockroaches to 300 Gy or more for some arctiid and pyralid moths. Factors such as oxygen level, and insect age and stage during irradiation, and many others, influence both the absorbed dose required for sterilization and the viability of irradiated insects. Consideration of these factors in the design of irradiation protocols can help to find a balance between the sterility and competitiveness of insects produced for programmes that release sterile insects. Many programmes apply 'precautionary' radiation doses to increase the security margin of sterilization, but this overdosing often lowers competitiveness to the point where the overall induced sterility in the wild population is reduced significantly. (author)

  14. RILIS-ionized mercury and tellurium beams at ISOLDE CERN

    Energy Technology Data Exchange (ETDEWEB)

    Day Goodacre, T., E-mail: thomas.day.goodacre@cern.ch [CERN (Switzerland); Billowes, J. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Chrysalidis, K. [CERN (Switzerland); Fedorov, D. V. [Petersburg Nuclear Physics Institute (Russian Federation); Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Molkanov, P. L. [Petersburg Nuclear Physics Institute (Russian Federation); Rossel, R. E.; Rothe, S.; Seiffert, C. [CERN (Switzerland); Wendt, K. D. A. [Johannes Gutenberg Universität, Institut für Physik (Germany)

    2017-11-15

    This paper presents the results of ionization scheme development for application at the ISOLDE Resonance Ionization Laser Ion Source (RILIS). Two new ionization schemes for mercury are presented: a three-step three-resonance ionization scheme, ionizing via an excitation to a Rydberg level and a three-step two-resonance ionization scheme, with a non-resonant final step to the ionization continuum that corresponded to a factor of four higher ionization efficiency. The efficiency of the optimal mercury ionization scheme was measured, together with the efficiency of a new three-step three resonance ionization scheme for tellurium. The efficiencies of the mercury and tellurium ionization schemes were determined to be 6 % and >18 % respectively.

  15. Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

    International Nuclear Information System (INIS)

    Blashenkov, Nikolai M; Lavrent'ev, Gennadii Ya

    2007-01-01

    The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied. (instruments and methods of investigation)

  16. Multiple ionization of atoms by ion impact

    International Nuclear Information System (INIS)

    DuBois, R.D.

    1988-01-01

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

  17. Propagation of ionizing waves in glow discharge

    International Nuclear Information System (INIS)

    Suzuki, T.

    1977-01-01

    Ionizing waves were produced along the positive column of a glow discharge in air by applying an impulse voltage to an electrode at one end of the column. Five photomultipliers and three current-sensing coils were used to observe how the waves were affected by the rise time and the magnitude of the applied impulses and by the electron density in the positive column of the glow discharge. It is shown that the speed of the ionizing waves increases with the slope of the applied impulses and with the preexisting electron density. The electron density is augmented about 100--200 times due to the buildup of ionization at the front of the waves. The theory was developed to explain the property of ionizing waves

  18. Experiments on Coulomb ionization by charged particles

    International Nuclear Information System (INIS)

    Andersen, J.U.; Laegsgaard, E.; Lund, M.

    1978-01-01

    Inner-shell ionization by light projectiles, i.e., in very asymmetric collisions, is often denoted 'Coulomb ionization' because it is caused by the Coulomb interaction between the electron and the projectile. Although with little justification, the term is also used to distinquish such processes, in which the projectile Coulomb field is a small perturbation, from ionization in more violent, nearly symmetric ion-atom collisions. A discussion of Coulomb ionization of atomic K shells is given, with emphasis on experimental methods and results. The discussion is not intended as a review of the field but rather as a progress report on the anthor's work on the subject. A more detailed account was recently presented at the ICPEAC meeting in Paris. (Auth.)

  19. New Croatian Act on Ionizing Radiation Protection

    International Nuclear Information System (INIS)

    Grgic, S.

    1998-01-01

    According to the new Croatian Act on ionizing radiation protection which is in a final stage of genesis, Ministry of Health of the Republic of Croatia is the governmental body responsible for all aspects relating sources of ionizing radiation in Croatia: practices, licenses, users, transport, in medicine and industry as well, workers with sources of ionizing radiation, emergency preparedness in radiological accidents, storage of radioactive wastes, x-ray machines and other machines producing ionizing radiation and radioactive materials in the environment. Ministry of Health is responsible to the Government of the Republic of Croatia, closely collaborating with the Croatian Radiation Protection Institute, health institution for the performance of scientific and investigation activities in the field of radiation protection. Ministry of Health is also working together with the Croatian Institute for the Occupational Health. More emphasis has been laid on recent discussion among the world leading radiation protection experts on justification of the last recommendations of the ICRP 60 publication. (author)

  20. Specification for symbol for ionizing radiation

    International Nuclear Information System (INIS)

    1974-01-01

    This Malaysia Standard specification specifies a symbol recommended for use only to signify the actual or potential presence of ionizing radiation (#betta#, α, #betta# only) and to identify objects, devices, materials or combinations of materials which emit such radiation. (author)

  1. Electron impact ionization of large krypton clusters

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  2. Tachyonic ionization cross sections of hydrogenic systems

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschitz, Roman [Department of Physics, Hiroshima University, 1-3-1 Kagami-yama, Higashi-Hiroshima 739-8526 (Japan)

    2005-03-11

    Transition rates for induced and spontaneous tachyon radiation in hydrogenic systems as well as the transversal and longitudinal ionization cross sections are derived. We investigate the interaction of the superluminal radiation field with matter in atomic bound-bound and bound-free transitions. Estimates are given for Ly-{alpha} transitions effected by superluminal quanta in hydrogen-like ions. The tachyonic photoelectric effect is scrutinized, in the Born approximation and at the ionization threshold. The angular maxima occur at different scattering angles in the transversal and longitudinal cross sections, which can be used to sift out longitudinal tachyonic quanta in a photon flux. We calculate the tachyonic ionization and recombination cross sections for Rydberg states and study their asymptotic scaling with respect to the principal quantum number. At the ionization threshold of highly excited states of order n {approx} 10{sup 4}, the longitudinal cross section starts to compete with photoionization, in recombination even at lower levels.

  3. Genetic effects of ionizing radiations in Eucaryocytes

    International Nuclear Information System (INIS)

    Jullien, Pierre

    1976-01-01

    The litterature on the genetic effects of ionizing radiations is reviewed, especially as concerns specific loci or chromosome mutations. Extrapolation from one species to another is considered as well as extra-nuclear mutations [fr

  4. Liquid ionization chambers for LET determination

    DEFF Research Database (Denmark)

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

    Liquid ionization chambers [1] (LICs) have have been used in the last decades as background dosemeters. Since a few years LICs are also commercially available for dosimetry and are used for measurements of dose distributions where a high spatial distribution is necessary. Also in the last decades...... a differential equation applying several simplifications and approximations leading to discrepancies between theory and experiments [3]. The theory predicts the collection efficiency as a function of the electrical field and was applied for both air filled ionization chambers and liquid filled ionization...... chambers. For liquids the LET can be roughly deduced from the collection efficiency dependency on the electrical field inside a liquid ionization chambers [4] using an extrapolation method. We solved the fundamental differential equation again presented by Jaffe numerically, but now taking into account...

  5. The critical ionization velocity - a bibliography

    International Nuclear Information System (INIS)

    Axnaes, I.; Brenning, N.; Raadu, M.A.

    1982-12-01

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

  6. The effect of ionizing radiation on cyanophyta

    International Nuclear Information System (INIS)

    Kondrat'eva, N.V.; Shevchenko, T.F.; Golubkova, M.G.

    1989-01-01

    Publication data on the effect of ionizing radiation on cyanophyta are generalized. The conclusion about the presence of premises for forming cyanophyta radiobiology as special direction of procaryotic algae investigation is made

  7. Penning ionization processes studied by electron spectroscopy

    International Nuclear Information System (INIS)

    Yencha, A.J.

    1978-01-01

    The technique of measuring the kinetic energy of electrons ejected from atomic or molecular species as a result of collisional energy transfer between a metastable excited rare gas atom and an atom or molecule is known as Penning ionization spectroscopy. Like the analogous photoionization process of photoelectron spectroscopy, a considerable amount of information has been gained about the ionization potentials of numerous molecular systems. It is, in fact, through the combined analyses of photoelectron and Penning electron spectra that affords a probe of the particle-particle interactions that occur in the Penning process. In this paper a short survey of the phenomenon of Penning ionization, as studied by electron spectroscopy, will be presented as it pertains to the ionization processes of simple molecules by metastable excited atoms. (author)

  8. Modeling of Plutonium Ionization Probabilities for Use in Nuclear Forensic Analysis by Resonance Ionization Mass Spectrometry

    Science.gov (United States)

    2016-12-01

    masses collide, they form a supercritical mass . Criticality refers to the neutron population within the system. A critical system is one that can...Spectrometry, no. 242, pp. 161–168, 2005. [9] S. Raeder, “Trace analysis of actinides in the environment by means of resonance ionization mass ...first ionization potential of actinide elements by resonance ionization mass spectrometry.” Spectrochimica Acta part B: Atomic Spectroscopy. vol. 52

  9. Conception of CTMSP ionizing radiation calibration laboratory

    International Nuclear Information System (INIS)

    Silva, Raimundo Dias da; Kibrit, Eduardo

    2009-01-01

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

  10. Fundamental studies of molecular multiphoton ionization

    International Nuclear Information System (INIS)

    Miller, J.C.; Compton, R.N.

    1984-04-01

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

  11. Bound electron nonlinearity beyond the ionization threshold

    OpenAIRE

    Wahlstrand, J. K.; Zahedpour, S.; Bahl, A.; Kolesik, M.; Milchberg, H. M.

    2018-01-01

    Although high field laser-induced ionization is a fundamental process underlying many applications, there have been no absolute measurements of the nonlinear polarizability of atoms and molecules in the presence of ionization. Such information is crucial, for example, for understanding the propagation of high intensity ultrashort pulses in matter. Here, we present absolute space- and time-resolved measurements of the ultrafast laser-driven nonlinear polarizability in argon, krypton, xenon, ni...

  12. Tomographic scanning apparatus with ionization detector means

    International Nuclear Information System (INIS)

    1981-01-01

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

  13. 100 years of ionizing radiation protection

    International Nuclear Information System (INIS)

    Baltrukiewicz, Z.; Musialowicz, T.

    1999-01-01

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

  14. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

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

  15. Commercial applications of food ionization in France

    International Nuclear Information System (INIS)

    Santos, Pierre-Louis

    1994-01-01

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

  16. Resonantly enhanced collisional ionization measurements of radionuclides

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1986-01-01

    The authors developed a new laser technique to analyze for radionuclides at extremely low levels. The technique, called resonantly enhanced collisional ionization (RECI), uses two nitrogen-laser pumped dye lasers to excite the target isotope to a high-energy Rydberg state. Atoms in these Rydberg states (within a few hundred wavenumbers in energy from the ionization threshold) efficiently ionize upon colliding with an inert gas and the ions can be detected by conventional means. The principal advantage of resonantly-enhanced collisional ionization is the extreme sensitivity coupled with its relative simplicity and low cost. Actinides typically have an ionization potential of about 6eV (uranium I.P. = 6.2 eV, plutonium I.P. = 5.7 eV). Two-step laser excitation to a state just below threshold requires wavelengths in the blue region of the visible spectrum. They showed that when both steps in the excitation process are resonant steps, relatively low-power lasers can populate the Rydberg state with almost unit efficiency. This is because the resonant excitations have much larger cross-sections than do photoionization processes. They also demonstrated that a few torr of a buffer gas will cause most of the excited-state atoms to be ionized

  17. Characteristics of a Dry Fog Ionizer

    International Nuclear Information System (INIS)

    Murata, Y; Kudo, Y; Yonezawa, M

    2008-01-01

    The newly developed 'Dry Fog Ionizer' generates charged dry fog. The dry fog consists of very fine water droplets 8μm in mean diameter. This system consists of a dry fog nozzle (H.Ikeuchi and Co., LTD.), a ring electrode for induction charging (50mm outside diameter, and 10mm thick) in front of the nozzle, and a fan for dissipating charged dry fog. The ring electrode is DC or AC-biased and fine droplets ejected from the nozzle are electrified by induction charging. The particle size of the charged water droplets are reduced through evaporation during the transporting process by air flow, and completely evaporate approximately 2m from the nozzle under normal atmospheric conditions (25 deg. C, 60%R.H.) leaving high density ions. Using this system, high density ionic space charge can be realized in a remote spot from the ionizer. By this principle, the Dry Fog Ionizer shows strong charge-eliminating ability in the region away from the ionizer. When a dc bias of 5kV was applied to a ring electrode with the rate of water flow from the nozzle being 21/h, an ionic space-charge density of 1200nC /m 3 was able to be obtained at a distance 2m away from the ionizer, which was 10 2 times the value produced by an ordinary corona-type ionizer with an air blower.

  18. Comparison among different CT ionization chambers

    International Nuclear Information System (INIS)

    Castro, Maysa C. de; Xavier, Marcos; Caldas, Linda V.E.

    2015-01-01

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

  19. Inner shell ionization accompanying nuclear collisions

    International Nuclear Information System (INIS)

    Sujkowski, Z.

    1987-01-01

    Selected phenomena leading to inner shell ionization and being of relevance for nuclear physics are discussed. The selection emphasizes the K-shell ionization induced in head-on collisions by fast light and medium-heavy ions. Cross-sections are reviewed. Effects of multiple inner shell ionization on the K X-ray spectra are illustrated with recent results. Implications for nuclear experiments are noted. Use of atomic observables as clocks for proton induced nuclear reactions is reviewed. Prospects for H.I. reactions are discussed. Preliminary experimental results on the direct K-shell ionization accompanying H.I. fusion reactions are presented. The post-collisional K-shell ionization due to internal conversion of γ-rays is discussed as the dominating contribution to the ionization for residues of dissipative nuclear reactions with Z > 40. Systematics of the corresponding K X-ray multiplicities are presented for rotational nuclei. These multiplicity values can be used for determining cross-sections for e.g. incomplete fusion reactions. Examples of such applications are given. Also discussed is the use of target K X-rays for normalization purposes and of the post-collisional, residue K X-rays in the studies of high spin phenomena. 96 references, 35 figures, 3 tables

  20. Microwave ionization of hydrogen atoms below the classical chaos border

    Energy Technology Data Exchange (ETDEWEB)

    Bluemel, R; Smilansky, U

    1987-01-01

    We present and discuss theoretical predictions for the occurrence of radiation induced ionization of hydrogen atoms in fields which are well below the classical ionization threshold. Strong ionization occurs due to enhanced population of a band of high n states which ionize easily. This enhancement happens only at rather narrowly defined field values, and is explained in terms of avoided crossings of Floquet levels.

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

    International Nuclear Information System (INIS)

    Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

    2013-01-01

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

  2. Tissue macrophage activation: a shared sign of exposure to ionizing and non-ionizing radiation

    International Nuclear Information System (INIS)

    Petrenyov, D.R.

    2012-01-01

    The features of oxidative metabolism of peritoneal macrophages were studied in rats exposed to ionizing and non-ionizing radiation. An increased RNS and ROS production reported in animals exposed to both source of radiation showing non-specific response of organism. (authors)

  3. Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

    International Nuclear Information System (INIS)

    He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

    2012-01-01

    Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

  4. Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

    NARCIS (Netherlands)

    Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

    1991-01-01

    Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

  5. Large area gridded ionisation chamber and electrostatic precipitator and their application to low-level alpha-spectrometry of environmental air samples

    International Nuclear Information System (INIS)

    Hoetzl, H.; Winkler, R.

    1977-01-01

    A high-resolution, parallel plate Frisch grid ionization chamber with an efficient area of 3000 cm 2 , and a large area electrostatic precipitator were developed and applied to direct alpha spectrometry of air dust. Using an argon-methane mixture (P-10 gas) at atmospheric pressure the resolution of the detector system is 22 keV FWHM at 5 MeV. After sampling for one week and decay of short-lived natural activity, the sensitivity of the procedure for long-lived alpha emitters is about 0.1 fCi/m 3 taking 3 Σσ of background as the detection limit with 1000 min counting time. (author)

  6. Multi-fold correlations between 252Cf (sf) fragments and fission neutrons/γ-rays

    International Nuclear Information System (INIS)

    Duering, I.; Jahnke, U.

    1993-01-01

    Direction-sensitive spectroscopy of fission fragments (twin ionization chamber with Frisch grids) was combined with the measurement of neutron multiplicity distribution (P(ν), average total γ-ray energy (2x2 π Gd-loaded scintillator) as well as energy and angular distribution of neutrons and γ-rays. Based on the careful account for necessary corrections, scission configurations given by mass asymmetry, elongation (total kinetic energy of fragments), and shape asymmetry (ν 1 /ν 2 ) can be studied exclusively in correlation with differential distributions of emission products. The scheme for correcting the neutron multiplicity distribution including its separation into the contributions from the complementary fragments is presented in detail. The mass yield for extreme anti ν 1 / anti ν 2 ratios show fine structures indicating the cold shape-asymmetric fission. (orig.)

  7. Development of AN Active 238UF6 Gas Target

    Science.gov (United States)

    Eckardt, C.; Enders, J.; Freudenberger, M.; Göök, A.; von Neumann-Cosel, P.; Oberstedt, A.; Oberstedt, S.

    2014-09-01

    Detailed studies of the fission process, e.g., the search for parity nonconservation (PNC) effects, the energy dependence of fission modes or the population of fission isomers, depend on high quality data, therefore requiring high luminosities. An active gas target containing uranium may overcome the deterioration of energy and angular resolution caused by large solid target thicknesses. A single Frisch-grid ionization chamber has been built to test a mixture of standard counting gases (e.g., argon) with depleted uranium hexafluoride (238UF6), utilizing a triple alpha source to evaluate signal quality and drift velocity. For mass fractions of up to 4 percent of 238U the drift velocity increases with rising UF6 content, while a good signal quality and energy resolution is preserved.

  8. Efficient ionizer for polarized H- formation

    International Nuclear Information System (INIS)

    Alessi, J.G.

    1985-01-01

    An ionizer is under development for a polarized H - source based on the resonant charge exchange reaction polarized H 0 + D - → polarized H - + D 0 . The polarized H 0 beam passes through the center of a magnetron surface-plasma source having an annular geometry, where it crosses a high current (approx.0.5 A), 200 eV D - beam. Calculations predict an H 0 → H - ionization efficiency of approx.7%, more than an order of magnitude higher than that obtained on present ground state atomic beam sources. In initial experiments using an unpolarized H 0 beam, H - currents in excess of 100 μA have been measured. While the ionization efficiency is now only about the same as other methods (Cs beam, for example), the results are encouraging since it appears that by injecting positive ions to improve the space-charge neutralization, and by improving the extraction optics, considerable gains in intensity will be made. We will then use this ionizer with a polarized H 0 beam, and measure the polarization of the resulting H - beam. If no depolarization is observed this ionizer will be combined with an atomic beam, cooled to 5 to 6 K, to give a polarized H - beam expected to be in the milliampere range for use in the AGS

  9. Pressing problems of measurement of ionizing radiations

    International Nuclear Information System (INIS)

    Fominykh, V.I.; Yudin, M.F.

    1993-01-01

    The current system for ensuring the unity of measurements in the Russian Federation and countries of the former Soviet Union ensures a high quality of dosimetric, radiometric, and spectrometric measurements in accordance with the recommendations of the Consulative Committee on Standards for Measurements of Ionizing Radiations of the International Bureau of Weights and Measures (IBWM), International Organization on Radiological Units (ICRU), International Commission on Radiological Protection (ICRP), International Organization on Legislative Metrology (IOLM), International Atomic Energy Agency (IAEA), World Health Organization (WHO), etc. Frequent collation of the national primary and secondary standards of Russia with those of IBWM and the leading national laboratories of the world facilitate mutual verification of the measurements of ionizing radiations. The scope of scientific and scientific-technical problems that can be solved by using ionizing radiations has expanded significantly in recent years. In this paper the authors consider some pressing problems of the metrology of ionizing radiations which have arisen as a result of this expansion. These include the need for unity and reliability of measurements involved in radiation protection, the measurement of low doses involving low dose rates, ensuring the unity of measurements when monitoring the radiological security of the population, the need for more uniformity on an international scale regarding the basic physical quantities and their units for characterizing radiation fields, determination of the accuracy of measurement of the radiation dose absorbed by an irradiated tissue or organ, and the development of complex standards for ionizing radiations. 5 refs., 1 tab

  10. The GBT Diffuse Ionized Gas Survey (GDIGS)

    Science.gov (United States)

    Luisi, Matteo; Anderson, Loren Dean; Liu, Bin; Bania, Thomas; Balser, Dana; Wenger, Trey; Haffner, Lawrence Matthew

    2018-01-01

    Diffuse ionized gas in the Galactic mid-plane known as the "Warm Ionized Medium" (WIM) makes up ~20% of the gas mass of the Milky Way and >90% of its ionized gas. It is the last major component of the interstellar medium (ISM) that has not yet been studied at high spatial and spectral resolution, and therefore many of its fundamental properties remain unclear. The Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS) is a new large survey of the Milky Way disk at C-band (4-8 GHz). The main goals of GDIGS are to investigate the properties of the WIM and to determine the connection between the WIM and high-mass star formation over the Galactic longitude and latitude range of 32 deg > l > -5 deg, |b| resolution of 0.5 km/s and rms sensitivities of ~3 mJy per beam. GDIGS observations are currently underway and are expected to be completed by late 2018. These data will allow us to: 1) Study for the first time the inner-Galaxy WIM unaffected by confusion from discrete HII regions, 2) determine the distribution of the inner Galaxy WIM, 3) investigate the ionization state of the WIM, 4) explore the connection between the WIM and HII regions, and 5) analyze the effect of leaked photons from HII regions on ISM dust temperatures.

  11. Surface ionization ion source with high current

    International Nuclear Information System (INIS)

    Fang Jinqing; Lin Zhizhou; Yu Lihua; Zhan Rongan; Huang Guojun; Wu Jianhua

    1986-04-01

    The working principle and structure of a surface ionization ion source with high current is described systematically. Some technological keypoints of the ion source are given in more detail, mainly including: choosing and shaping of the material of the surface ionizer, heating of the ionizer, distributing of working vapour on the ionizer surface, the flow control, the cooling problem at the non-ionization surface and the ion optics, etc. This ion source has been used since 1972 in the electromagnetic isotope separator with 180 deg angle. It is suitable for separating isotopes of alkali metals and rare earth metals. For instance, in the case of separating Rubidium, the maximum ion current of Rbsup(+) extracted from the ion source is about 120 mA, the maximum ion current accepted by the receiver is about 66 mA, the average ion current is more than 25 mA. The results show that our ion source have advantages of high ion current, good characteristics of focusing ion beam, working stability and structure reliability etc. It may be extended to other fields. Finally, some interesting phenomena in the experiment are disccused briefly. Some problems which should be investigated are further pointed out

  12. Conceptual basis of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Payne, M.G.

    1984-04-01

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

  13. Recent attoclock measurements of strong field ionization

    International Nuclear Information System (INIS)

    Pfeiffer, Adrian N.; Cirelli, Claudio; Smolarski, Mathias; Keller, Ursula

    2013-01-01

    Highlights: ► The attoclock measures time by electron streaking with elliptically polarized light. ► Precision measurements reveal details about the laser-induced tunneling current flow. ► Multielectron effects play an important role when the polarizability is large. ► Double ionization experiments show evidence of novel electron correlation mechanisms. - Abstract: The attoclock is a powerful, new, and unconventional experimental tool to study fundamental attosecond dynamics on an atomic scale. We have demonstrated the first attoclock with the goal to measure the tunneling delay time in laser-induced ionization of helium and argon atoms, with surprising results. It was found that the time delay in tunneling is zero for helium and argon atoms within the experimental uncertainties of a few 10’s of attoseconds. Furthermore we showed that the single active electron approximation is not sufficient even for atoms such as argon and the parent-ion interaction is much more complex than normally assumed. For double ionization of argon we found again surprising results because the ionization time of the first electron is in good agreement with the predictions, whereas the ionization of the second electron occurs significantly earlier than predicted and the two electrons exhibit some unexpected correlation

  14. Recent attoclock measurements of strong field ionization

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, Adrian N., E-mail: apfeiff@phys.ethz.ch [Physics Department, ETH Zurich, 8093 Zurich (Switzerland); Cirelli, Claudio; Smolarski, Mathias; Keller, Ursula [Physics Department, ETH Zurich, 8093 Zurich (Switzerland)

    2013-03-12

    Highlights: ► The attoclock measures time by electron streaking with elliptically polarized light. ► Precision measurements reveal details about the laser-induced tunneling current flow. ► Multielectron effects play an important role when the polarizability is large. ► Double ionization experiments show evidence of novel electron correlation mechanisms. - Abstract: The attoclock is a powerful, new, and unconventional experimental tool to study fundamental attosecond dynamics on an atomic scale. We have demonstrated the first attoclock with the goal to measure the tunneling delay time in laser-induced ionization of helium and argon atoms, with surprising results. It was found that the time delay in tunneling is zero for helium and argon atoms within the experimental uncertainties of a few 10’s of attoseconds. Furthermore we showed that the single active electron approximation is not sufficient even for atoms such as argon and the parent-ion interaction is much more complex than normally assumed. For double ionization of argon we found again surprising results because the ionization time of the first electron is in good agreement with the predictions, whereas the ionization of the second electron occurs significantly earlier than predicted and the two electrons exhibit some unexpected correlation.

  15. Deep-down ionization of protoplanetary discs

    Science.gov (United States)

    Glassgold, A. E.; Lizano, S.; Galli, D.

    2017-12-01

    The possible occurrence of dead zones in protoplanetary discs subject to the magneto-rotational instability highlights the importance of disc ionization. We present a closed-form theory for the deep-down ionization by X-rays at depths below the disc surface dominated by far-ultraviolet radiation. Simple analytic solutions are given for the major ion classes, electrons, atomic ions, molecular ions and negatively charged grains. In addition to the formation of molecular ions by X-ray ionization of H2 and their destruction by dissociative recombination, several key processes that operate in this region are included, e.g. charge exchange of molecular ions and neutral atoms and destruction of ions by grains. Over much of the inner disc, the vertical decrease in ionization with depth into the disc is described by simple power laws, which can easily be included in more detailed modelling of magnetized discs. The new ionization theory is used to illustrate the non-ideal magnetohydrodynamic effects of Ohmic, Hall and Ambipolar diffusion for a magnetic model of a T Tauri star disc using the appropriate Elsasser numbers.

  16. Electron-impact ionization of Mo+

    International Nuclear Information System (INIS)

    Ludlow, J.A.; Loch, S.D.; Pindzola, M.S.

    2005-01-01

    The electron-impact direct ionization cross section for Mo + is calculated using both nonperturbative close-coupling and perturbative distorted-wave methods. When distorted-wave calculations for 4d 5 →4d 4 direct ionization are added to distorted-wave calculations for 4p→nl excitation-autoionization, the experimental measurements are found to be 60% lower than the theoretical predictions. Inclusion of nonperturbative three-body Coulomb effects, present in time-dependent close-coupling calculations, are found to reduce the distorted-wave 4d 5 →4d 4 direct ionization cross section by 25%. This is by far the largest reduction yet seen when comparing the two methods for direct subshell ionization of an atomic positive ion in the ground state. However, when the close-coupling calculations for 4d 5 →4d 4 direct ionization are added to distorted-wave calculations for 4p→nl excitation-autoionization, the experimental measurements are still 45% lower than the theoretical predictions. Although we further investigate correlation effects in the initial target state and term-dependent potential effects in the ejected electron state in an attempt to understand the small magnitude of the experimental measurements, the discrepancy between theory and experiment remains unexplained

  17. Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions

    International Nuclear Information System (INIS)

    Pajek, M.; Banas, D.; Semaniak, J.; Braziewicz, J.; Majewska, U.; Chojnacki, S.; Czyzewski, T.; Fijal, I.; Jaskola, M.; Glombik, A.; Kretschmer, W.; Trautmann, D.; Lapicki, G.; Mukoyama, T.

    2003-01-01

    The multiple-ionization and coupling effects in L-shell ionization of atoms by heavy-ion impact have been studied by measuring the L x-ray production cross sections in solid targets of Au, Bi, Th, and U bombarded by oxygen ions in the energy range 6.4-70 MeV. The measured L x-ray spectra were analyzed using the recently proposed method accounting for the multiple-ionization effects, such as x-ray line shifting and broadening, which enables one to obtain the ionization probabilities for outer shells. The L-subshell ionization cross sections have been obtained from measured x-ray production cross sections for resolved Lα 1,2 , Lγ 1 , and Lγ 2,3 transitions using the L-shell fluorescence and Coster-Kronig yields being substantially modified by the multiple ionization in the M and N shells. In particular, the effect of closing of strong L 1 -L 3 M 4,5 Coster-Kronig transitions in multiple-ionized atoms was evidenced and discussed. The experimental ionization cross sections for the L 1 , L 2 , and L 3 subshells have been compared with the predictions of the semiclassical approximation (SCA) and the ECPSSR theory that includes the corrections for the binding-polarization effect within the perturbed stationary states approximation, the projecticle energy loss, and Coulomb deflection effects as well as the relativistic description of inner-shell electrons. These approaches were further modified to include the L-subshell couplings within the ''coupled-subshell model'' (CSM). Both approaches, when modified for the coupling effects, are in better agreement with the data. Particularly, the predictions of the SCA-CSM calculations reproduce the experimental L-subshell ionization cross section reasonably well. Remaining discrepancies are discussed qualitatively, in terms of further modifications of the L-shell decay rates caused by a change of electronic wave functions in multiple-ionized atoms

  18. Ionizing radiation and genetic risks

    Energy Technology Data Exchange (ETDEWEB)

    Sankaranarayanan, K. [Department of Toxicogenetics, Leiden University Medical Centre, Sylvius Laboratories, Wassenaarseweg 72, 2333 AL Leiden (Netherlands)]. E-mail: sankaran@lumc.nl; Wassom, J.S. [YAHSGS, LLC, Richland, WA 99352 (United States); Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States)

    2005-10-15

    Recent estimates of genetic risks from exposure of human populations to ionizing radiation are those presented in the 2001 report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). These estimates incorporate two important concepts, namely, the following: (1) most radiation-induced mutations are DNA deletions, often encompassing multiple genes, but only a small proportion of the induced deletions is compatible with offspring viability; and (2) the viability-compatible deletions induced in germ cells are more likely to manifest themselves as multi-system developmental anomalies rather than as single gene disorders. This paper: (a) pursues these concepts further in the light of knowledge of mechanisms of origin of deletions and other rearrangements from two fields of contemporary research: repair of radiation-induced DNA double-strand breaks (DSBs) in mammalian somatic cells and human molecular genetics; and (b) extends them to deletions induced in the germ cell stages of importance for radiation risk estimation, namely, stem cell spermatogonia in males and oocytes in females. DSB repair studies in somatic cells have elucidated the roles of two mechanistically distinct pathways, namely, homologous recombination repair (HRR) that utilizes extensive sequence homology and non-homologous end-joining (NHEJ) that requires little or no homology at the junctions. A third process, single-strand annealing (SSA), which utilizes short direct repeat sequences, is considered a variant of HRR. HRR is most efficient in late S and G{sub 2} phases of the cell cycle and is a high fidelity mechanism. NHEJ operates in all cell cycle phases, but is especially important in G{sub 1}. In the context of radiation-induced DSBs, NHEJ is error-prone. SSA is also an error-prone mechanism and its role is presumably similar to that of HRR. Studies in human molecular genetics have demonstrated that the occurrence of large deletions, duplications or other

  19. Ionizing radiation and genetic risks

    International Nuclear Information System (INIS)

    Sankaranarayanan, K.; Wassom, J.S.

    2005-01-01

    Recent estimates of genetic risks from exposure of human populations to ionizing radiation are those presented in the 2001 report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). These estimates incorporate two important concepts, namely, the following: (1) most radiation-induced mutations are DNA deletions, often encompassing multiple genes, but only a small proportion of the induced deletions is compatible with offspring viability; and (2) the viability-compatible deletions induced in germ cells are more likely to manifest themselves as multi-system developmental anomalies rather than as single gene disorders. This paper: (a) pursues these concepts further in the light of knowledge of mechanisms of origin of deletions and other rearrangements from two fields of contemporary research: repair of radiation-induced DNA double-strand breaks (DSBs) in mammalian somatic cells and human molecular genetics; and (b) extends them to deletions induced in the germ cell stages of importance for radiation risk estimation, namely, stem cell spermatogonia in males and oocytes in females. DSB repair studies in somatic cells have elucidated the roles of two mechanistically distinct pathways, namely, homologous recombination repair (HRR) that utilizes extensive sequence homology and non-homologous end-joining (NHEJ) that requires little or no homology at the junctions. A third process, single-strand annealing (SSA), which utilizes short direct repeat sequences, is considered a variant of HRR. HRR is most efficient in late S and G 2 phases of the cell cycle and is a high fidelity mechanism. NHEJ operates in all cell cycle phases, but is especially important in G 1 . In the context of radiation-induced DSBs, NHEJ is error-prone. SSA is also an error-prone mechanism and its role is presumably similar to that of HRR. Studies in human molecular genetics have demonstrated that the occurrence of large deletions, duplications or other rearrangements

  20. Code of practice for ionizing radiation

    International Nuclear Information System (INIS)

    Khoo Boo Huat

    1995-01-01

    Prior to 1984, the use of ionizing radiation in Malaysia was governed by the Radioactive Substances Act of 1968. After 1984, its use came under the control of Act 304, called the Atomic Energy Licensing Act 1984. Under powers vested by the Act, the Radiation Protection (Basic Safety Standards) Regulations 1988 were formulated to regulate its use. These Acts do not provide information on proper working procedures. With the publication of the codes of Practice by The Standards and Industrial Research Institute of Malaysia (SIRIM), the users are now able to follow proper guidelines and use ionizing radiation safely and beneficially. This paper discusses the relevant sections in the following codes: 1. Code of Practice for Radiation Protection (Medical X-ray Diagnosis) MS 838:1983. 2. Code of Practice for Safety in Laboratories Part 4: Ionizing radiation MS 1042: Part 4: 1992. (author)

  1. Method and apparatus for analyzing ionizable materials

    International Nuclear Information System (INIS)

    Ehrlich, B.J.; Hall, R.C.; Thiede, P.W.

    1979-01-01

    An apparatus and method are described for analyzing a solution of ionizable compounds in a liquid. The solution is irradiated with electromagnetic radiation to ionize the compounds and the electrical conductivity of the solution is measured. The radiation may be X-rays, ultra-violet, infra-red or microwaves. The solution may be split into two streams, only one of which is irradiated, the other being used as a reference by comparing conductivities of the two streams. The liquid must be nonionizable and is preferably a polar solvent. The invention provides an analysis technique useful in liquid chromatography and in gas chromatography after dissolving the eluted gases in a suitable solvent. Electrical conductivity measurements performed on the irradiated eluent provide a quantitative indication of the ionizable materials existing within the eluent stream and a qualitative indication of the purity of the eluent stream. (author)

  2. Ionizing radiation and wild birds: a review

    International Nuclear Information System (INIS)

    Mellinger, P.J.; Schultz, V.

    1975-01-01

    Since the first atomic explosion, 16 July 1945 at the Trinity Site in south-central New Mexico, the impact of ionizing radiation on bird populations has been of concern to a few individuals. The proliferation of nuclear power plants has increased public concern as to possible deleterious effects of nuclear power plant operation on resident and migratory bird populations. Literature involving wild birds and ionizing radiation is not readily available, and only a few studies have been anywhere near comprehensive, with most effort directed towards monitoring radionuclide concentration in birds. The objective of the paper is to document the literature on wild birds and ionizing radiation including a brief description of pertinent papers

  3. Radiation ionization is an underestimated industrial technique

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    Industrial radiation ionization requires electron beams coming from an accelerator or gamma radiation from a radioactive source (Co 60 ). The energy deposed in the irradiated material modifies its chemical bounds or kills micro-organisms. This process is used in medical material sterilization, in disinfestation of stored and packaged food products, in the production of plastic, in the coloring of glass, in the hardening of electronic components and in the modification of the properties of semi-conductors. For 40 years radiation ionization has been investigated, UNO (United Nations Organization) and WHO (World Health Organisation) recommend it for food processing. With a growing rate of 15% per year for the last 15 years, radiation ionization is now widely used. More than 170 gamma irradiation facilities are operating throughout the world. (A.C.)

  4. Multiphoton ionization/dissociation of osmium tetroxide

    International Nuclear Information System (INIS)

    Ding, D.; Puretzky, A.A.; Compton, R.N.

    1993-01-01

    The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO 4 ) have been investigated from measurements of the kinetic energies of product ions (Os + , Os 2+ , OsO + , O 2 + , O + ) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os + ionization channel, such as OsO 4 →OsO 4-n +nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os + ion signal suggests that one or more of the steps leading to Os + ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow ( 2+ is shown to result primarily from REMPI of Os +

  5. Ionizing radiation effects on floating gates

    International Nuclear Information System (INIS)

    Cellere, G.; Paccagnella, A.; Visconti, A.; Bonanomi, M.

    2004-01-01

    Floating gate (FG) memories, and in particular Flash, are the dominant among modern nonvolatile memory technologies. Their performance under ionizing radiation was traditionally studied for the use in space, but has become of general interest in recent years. We are showing results on the charge loss from programmed FG arrays after 10 keV x-rays exposure. Exposure to ionizing radiation results in progressive discharge of the FG. More advanced devices, featuring smaller FG, are less sensitive to ionizing radiation that older ones. The reason is identified in the photoemission of electrons from FG, since at high doses it dominates over charge loss deriving from electron/hole pairs generation in the oxides

  6. Memory in Nonlinear Ionization of Transparent Solids

    International Nuclear Information System (INIS)

    Rajeev, P. P.; Simova, E.; Hnatovsky, C.; Taylor, R. S.; Rayner, D. M.; Corkum, P. B.; Gertsvolf, M.; Bhardwaj, V. R.

    2006-01-01

    We demonstrate a shot-to-shot reduction in the threshold laser intensity for ionization of bulk glasses illuminated by intense femtosecond pulses. For SiO 2 the threshold change serves as positive feedback reenforcing the process that produced it. This constitutes a memory in nonlinear ionization of the material. The threshold change saturates with the number of pulses incident at a given spot. Irrespective of the pulse energy, the magnitude of the saturated threshold change is constant (∼20%). However, the number of shots required to reach saturation does depend on the pulse energy. Recognition of a memory in ionization is vital to understand multishot optical or electrical breakdown phenomena in dielectrics

  7. Progress in zirconium resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Page, R.H.; Dropinski, S.C.; Worden, E.F.; Stockdale, J.A.D.

    1993-01-01

    The authors have examined the stepwise-resonant three-photon-ionization spectrum of neutral zirconium atoms using three separately-tunable pulsed visible dye lasers. The ground-level (first-step) transitions were chosen on the basis of demonstrated 91 Zr selectivity. Lifetimes of even-parity levels around 36,000 cm -1 , measured with the delayed-photoionization technique, range from 10 to 100 nsec. Direct ionization cross sections appear to be less than 10 -17 cm 2 ; newly-detected autoionizing levels give peak ionization cross sections (inferred from saturation fluences) up to 10 -15 cm 2 . Portions of Rydberg series converging to the 315 and 763 cm -1 levels of Zr + were identified. Clumps of autoionizing levels are thought to be due to Rydberg-valence mixing

  8. Protection policies for ionizing and UV radiation

    International Nuclear Information System (INIS)

    Bosnjakovic, B.F.M.

    1987-01-01

    Although ultraviolet radiation is generally considered as being part of non-ionizing radiation, the existing similarities with ionizing radiation are too striking to be overseen. A comparison of these two agents is becoming important in view of the increasing awareness of various environmental and health risks and the tendency to develop more uniform risk management policies with respect to the different physical and chemical agents. This paper explores the similarities and differences of UV and ionizing radiation from the point of view of policies either adopted or in development. Policy determinants include, among others, the following factors: biological effects, dosimetric quantities, relative contribution to exposure from different sources, hazard potential of different sources, quantification of detrimental consequences, public perception of the radiation hazards and regulation developments. These factors are discussed

  9. Ionizing radiation interactions with DNA: nanodosimetry

    International Nuclear Information System (INIS)

    Bug, Marion; Nettelbeck, Heidi; Hilgers, Gerhard; Rabus, Hans

    2011-01-01

    The metrology of ionizing radiation is based on measuring values that are averaged over macroscopic volume elements, for instance the energy dose is defined as ratio of the energy deposited on the absorber and the absorber mass. For biological or medical radiation effects the stochastic nature of radiation interaction id of main importance, esp. the interaction of ionizing radiation with the DNA as the genetic information carrier. For radiotherapy and risk evaluation purposes a comprehensive system of radiation weighing factors and other characteristics, like radiation quality or relative biological efficacy was developed. The nanodosimetry is aimed to develop a metrological basis relying on physical characteristics of the microscopic structure of ionizing radiation tracks. The article includes the development of experimental nanodosimetric methods, the respective calibration techniques, Monte-Carlo simulation of the particle track microstructure and the correlation nanodosimetry and biological efficiency.

  10. Guided ionization waves: Theory and experiments

    International Nuclear Information System (INIS)

    Lu, X.; Naidis, G.V.; Laroussi, M.; Ostrikov, K.

    2014-01-01

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

  11. A prototype ionization profile monitor for RHIC

    International Nuclear Information System (INIS)

    Connolly, R.; Cameron, P.; Ryan, W.

    1997-01-01

    Transverse beam profiles in the Relativistic Heavy-Ion Collider (RHIC) will be measured with ionization profile monitors (IPM's). Each IPM collects and measures the distribution of electrons in the beamline resulting from residual gas ionization during bunch passage. The electrons are swept transversely from the beamline and collected on strip anodes oriented parallel to the beam axis. At each bunch passage the charge pulses are amplified, integrated, and digitized for display as a profile histogram. A prototype detector was tested in the injection line during the RHIC Sextant Test. This paper describes the detector and gives results from the beam tests

  12. Effect of ionizing radiations on connective tissue

    International Nuclear Information System (INIS)

    Altman, K.I.; Gerber, G.B.

    1980-01-01

    The effects of ionizing radiations on connective tissue in lung, heart, vasculature, kidney, skin, and skeletal tissues are reviewed. Special emphasis is given to the effect of ionizing radiations on vasculo-connective tissue and fibrotic changes following radiation-induced injury to organs and tissues. In order to put the subject matter in proper prospective, the general biochemistry, physiology, and pathology of connective tissue is reviewed briefly together with the participation of connective tissue in disease. The review closes with an assessment of future problems and an enumeration and discussion of important, as yet unanswered questions

  13. The Muon Ionization Cooling Experiment User Software

    Science.gov (United States)

    Dobbs, A.; Rajaram, D.; MICE Collaboration

    2017-10-01

    The Muon Ionization Cooling Experiment (MICE) is a proof-of-principle experiment designed to demonstrate muon ionization cooling for the first time. MICE is currently on Step IV of its data taking programme, where transverse emittance reduction will be demonstrated. The MICE Analysis User Software (MAUS) is the reconstruction, simulation and analysis framework for the MICE experiment. MAUS is used for both offline data analysis and fast online data reconstruction and visualization to serve MICE data taking. This paper provides an introduction to MAUS, describing the central Python and C++ based framework, the data structure and and the code management and testing procedures.

  14. Generalized Bessel functions in tunnelling ionization

    International Nuclear Information System (INIS)

    Reiss, H R; Krainov, V P

    2003-01-01

    We develop two new approximations for the generalized Bessel function that frequently arises in the analytical treatment of strong-field processes, especially in non-perturbative multiphoton ionization theories. Both these new forms are applicable to the tunnelling environment in atomic ionization, and are analytically much simpler than the currently used low-frequency asymptotic approximation for the generalized Bessel function. The second of the new forms is an approximation to the first, and it is the second new form that exhibits the well-known tunnelling exponential

  15. Electron Impact Ionization of C60

    International Nuclear Information System (INIS)

    Duenser, B.; Lezius, M.; Scheier, P.; Deutsch, H.; Maerk, T.D.

    1995-01-01

    Absolute partial and total cross sections for the electron impact ionization of C 60 have been measured using a novel approach for the absolute calibration. The results obtained reveal not only an anomalous large parent ion cross section (as compared to the other ionization channels), but also anomalies for the production of multiply charged parent and fragment ions. This special behavior has its origin in the specific electronic and geometric structure of C 60 . Semiclassical calculations for singly charged ions support the measured data

  16. Effects of low doses of ionizing radiation

    International Nuclear Information System (INIS)

    Anon.

    2008-01-01

    Ionizing radiation of cosmic or terrestrial origin is part of the environment in which all living things have evolved since the creation of the universe. The artificial radioactivity generated by medical diagnostic and treatment techniques, some industrial activities, radioactive fallout, etc. has now been added to this natural radioactivity. This article reviews the biological effects of the low doses of ionizing radiation to which the population is thus exposed. Their carcinogenic risk cannot simply be extrapolated from what we know about high-dose exposure. (author)

  17. Electron induced atomic inner-shell ionization

    International Nuclear Information System (INIS)

    Quarles, C.A.

    1974-01-01

    The current status of cross section measurements for atomic inner-shell ionization by electron bombardment is reviewed. Inner shell ionization studies using electrons as projectiles compliment the similar studies being done with heavy particles, and in addition can provide tests of the theory in those cases when relativistic effects and exchange effects are expected to be important. Both total cross sections and recently measured differential cross sections will be discussed and compared with existing theories where possible. Prospects for further experimental and theoretical work in this area of atomic physics using small electron accelerators will also be discussed

  18. Ionization of atoms by high energy photons

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Ioffe, A.F.

    1994-01-01

    Photoionization of atoms by high energy photons is considered. It is emphasized that in this frequency region the cross section and other characteristics of the process are strongly effected by electron shell polarization and rearrangement effects, including that due to inner vacancy Auger decay. In the effects of nuclear structure could be important and noticeable, i.e. of virtual or real excitation of the nucleus degrees of freedom and of the Quantum Electrodynamics vacuum. Ionization accompanied by secondary photon emission (Compton ionization) is analyzed in the considered domain of energies

  19. Ionizing radiation decreases human cancer mortality rates

    International Nuclear Information System (INIS)

    Luckey, T.D.

    1997-01-01

    Information from nine studies with exposed nuclear workers and military observers of atmospheric bomb explosions confirms the results from animal studies which showed that low doses of ionizing radiation are beneficial. The usual ''healthy worker effect'' was eliminated by using carefully selected control populations. The results from 13 million person-years show the cancer mortality rate of exposed persons is only 65.6% that of carefully selected unexposed controls. This overwhelming evidence makes it politically untenable and morally wrong to withhold public health benefits of low dose irradiation. Safe supplementation of ionizing radiation should become a public health service. (author)

  20. Direct Simulation of Reentry Flows with Ionization

    Science.gov (United States)

    Carlson, Ann B.; Hassan, H. A.

    1989-01-01

    The Direct Simulation Monte Carlo (DSMC) method is applied in this paper to the study of rarefied, hypersonic, reentry flows. The assumptions and simplifications involved with the treatment of ionization, free electrons and the electric field are investigated. A new method is presented for the calculation of the electric field and handling of charged particles with DSMC. In addition, a two-step model for electron impact ionization is implemented. The flow field representing a 10 km/sec shock at an altitude of 65 km is calculated. The effects of the new modeling techniques on the calculation results are presented and discussed.

  1. Saha's ionization equation for high Z elements

    International Nuclear Information System (INIS)

    Godwal, B.K.; Sikka, S.K.

    1977-01-01

    Saha's ionization equation has been solved for high Z elements with the aim of providing input for opacity calculations. Results are presented for two elements, tungsten and uranium. The ionization potentials have been evaluated using the simple Bhor's formula with suitable effective charges for ions. The reliability of the free electron density, ion concentrations, etc., obtained from the Saha's equation solutions has been checked by comparing the P and E computed from them with those given by the Thomas-Fermi-Dirac equation of state. The agreement between the two is good from temperatures above 0.2 keV. (author)

  2. A statistical mechanical model for equilibrium ionization

    International Nuclear Information System (INIS)

    Macris, N.; Martin, P.A.; Pule, J.

    1990-01-01

    A quantum electron interacts with a classical gas of hard spheres and is in thermal equilibrium with it. The interaction is attractive and the electron can form a bound state with the classical particles. It is rigorously shown that in a well defined low density and low temperature limit, the ionization probability for the electron tends to the value predicted by the Saha formula for thermal ionization. In this regime, the electron is found to be in a statistical mixture of a bound and a free state. (orig.)

  3. Surface ionization mass spectrometry of opiates

    International Nuclear Information System (INIS)

    Usmanov, D.T.

    2009-07-01

    Key words: surface ionization, adsorption, heterogeneous reactions, surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy, thermoemitter, opiates, extracts of biosamples. Subjects of study. The mass - spectrometric study of thermal - ion emission: surface ionization of opiates by on the surface of oxidized refractory metals. Purpose of work is to establish the regularities of surface ionization (SI) of multi-atomic molecule opiates and their mixtures develop the scientific base of SI methods for high sensitive and selective detection and analysis of these substances in the different objects, including biosamples. Methods of study: surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy. The results obtained and their novelty. For the first time, SI of molecule opiates on the oxidized tungsten surface has been studied and their SI mass-spectra and temperature dependences of ion currents have been obtained, the characteristic heterogeneous reactions of an adsorbed molecules and the channels of monomolecular decays vibrationally-excited ions on their way in mass-spectrometry have been revealed, sublimation energy has been defined, the activation energy of E act , of these decays has been estimated for given period of time. Additivity of the SI mass-spectra of opiate mixtures of has been established under conditions of joint opiate adsorption. High selectivity of SI allows the extracts of biosamples to be analyzed without their preliminary chromatographic separation. The opiates are ionized by SI with high efficiency (from 34 C/mol to 112 C/mol), which provides high sensitivity of opiate detection by SI/MS and APTDSIS methods from - 10 -11 g in the samples under analysis. Practical value. The results of these studies create the scientific base for novel SI methods of high sensitive detection and analysis of the trace amounts of opiates in complicated mixtures, including biosamples without their preliminary

  4. The situation of knowledge on ionizing radiation

    International Nuclear Information System (INIS)

    2005-01-01

    Occupational exposure to ionizing radiation occurs: during sources use, during the use of matter including radioactivity used for other properties than their radioactivity, in presence of natural radioactivity on the working area, following an accident during an industrial process. to protect man taken into account the incurred risk, goes by the risk evaluation, in taking into account the industrial process and exposure conditions of persons, then by the application of prevention measures that aim to control the contamination risks by radioactive matters as well as the exposure risks to ionizing radiations. (N.C.)

  5. Ionizing radiation environment for the TOMS mission

    Science.gov (United States)

    Lauriente, M.; Maloy, J. O.; Vampola, A. L.

    1992-01-01

    The Total Ozone Mapping Spectrometer (TOMS) will fly on several different spacecraft, each having an orbit which is approximately polar and 800-980 km in altitude. A description is given of the computer-based tools used for characterizing the spacecraft interactions with the ionizing radiation environment in orbit and the susceptibility requirements for ionizing radiation compatibility. The peak flux from the model was used to derive the expected radiation-induced noise in the South Atlantic Anomaly for the new TOMS instruments intended to fly on Advanced Earth Observatory System and Earth Probe.

  6. Ionization smoke detector and alarm system

    International Nuclear Information System (INIS)

    1974-01-01

    An ionization smoke detector particularly suited to residential use is disclosed. The detector is battery-operated and is connected with a non-latching, pulsating alarm circuit. The detector has a sensing chamber formed by a perforated metallic shell and an electrode within which an insulated radiation source is centrally positioned to generate an ionization current for detecting smoke or other similar aerosols. The alarm circuit provides a pulsating alarm signal when smoke levels above a pre-determined value are sensed. The alarm circuit also includes a low voltage detection circuit for sounding the alarm when the end of useful battery life is approaching. (Auth.)

  7. A prototype ionization profile monitor for RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, R.; Cameron, P.; Ryan, W. [and others

    1997-07-01

    Transverse beam profiles in the Relativistic Heavy-Ion Collider (RHIC) will be measured with ionization profile monitors (IPM`s). Each IPM collects and measures the distribution of electrons in the beamline resulting from residual gas ionization during bunch passage. The electrons are swept transversely from the beamline and collected on strip anodes oriented parallel to the beam axis. At each bunch passage the charge pulses are amplified, integrated, and digitized for display as a profile histogram. A prototype detector was tested in the injection line during the RHIC Sextant Test. This paper describes the detector and gives results from the beam tests.

  8. Simulation study of the ionizing front in the critical ionization velocity phenomenon

    International Nuclear Information System (INIS)

    Machida, S.; Goertz, C.K.; Lu, G.

    1988-01-01

    Simulations of the Critical Ionization Velocity (CIV) for a neutral gas cloud moving across the static magnetic field are made. We treat a low-β plasma and use a 2-1/2 D electrostatic code linked with our Plasma and Neutral Interaction Code (PANIC). Our study is focused on the understanding of the interface between the neutral gas cloud and the surrounding plasma where the strong interaction takes place. We assume the existence of some hot electrons in the ambient plasma to provide a seed ionization for CIV. When the ionization starts a sheath-like structure is formed at the surface of the neutral gas (Ionizing Front). In that region the crossfield component of the electric field causes the electron to E x B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. Thus the kinetic energy of the drifting electrons can be large enough for electron impact ionization. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the ionization front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating and additional ionization. The overall structure is studied by developing a simple analytic model as well as making simulation runs. (author)

  9. Chemical data on ionizing and non-ionizing angiographic contrast materials

    International Nuclear Information System (INIS)

    Bonati, F.

    1980-01-01

    The cardiovascular effects of ionizing and non-ionizing contrast media are compared in experimental animals and in isolated heart preparations. The following parameters were recorded: peripheric arterial diastolic pressure, heart rate, duration of asystolic period, respiratory rate, contractility of the myocardium (dp/dt, LVSP, Vsub(max), EDV, ESV, SV). The observed changes are mainly due to the higher osmotic activity of the contrast media, as similar alterations were recorded after the injection of hyperosmotic glucose solution. It is concluded that administration of non-ionizing contrast media results in significantly less cardiovascular side effects. (L.E.)

  10. New ionization fractions for the lithium- and helium-like ionization stages of calcium and iron

    International Nuclear Information System (INIS)

    Doyle, J.G.; Raymond, J.C.

    1981-01-01

    The high resolution X-ray spectra of Ca XIX and Fe XXV observed during a solar flare on 1979 March 25 have been re-interpreted using new ionization fractions for Ca XVIII, Ca XIX, Fe XXIV and Fe XXV. These new calculations substantially change the interpretation of the spectra, implying the flare to be ionizing during the rise phase and recombining during the decay phase. The results favour the ECIP ionization rates over those of Lotz, though other interpretations are possible. (author)

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

    DEFF Research Database (Denmark)

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

    1996-01-01

    Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

  12. Fluctuation charge effects in ionization fronts

    International Nuclear Information System (INIS)

    Arrayas, Manuel; Trueba, Jose L; Baltanas, J P

    2008-01-01

    In this paper, we study the effects of charge fluctuations on the propagation of both negative and positive ionization fronts in streamer discharges. We show that fronts accelerate when random charge creation events are present. This effect might play a similar role to photoionization in order to make the front move faster

  13. Fluctuation charge effects in ionization fronts

    Energy Technology Data Exchange (ETDEWEB)

    Arrayas, Manuel; Trueba, Jose L [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain); Baltanas, J P [Departamento de Fisica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Sevilla (Spain)

    2008-05-21

    In this paper, we study the effects of charge fluctuations on the propagation of both negative and positive ionization fronts in streamer discharges. We show that fronts accelerate when random charge creation events are present. This effect might play a similar role to photoionization in order to make the front move faster.

  14. Properties of Excitons Bound to Ionized Donors

    DEFF Research Database (Denmark)

    Skettrup, Torben; Suffczynski, M.; Gorzkowski, W.

    1971-01-01

    Binding energies, interparticle distances, oscillator strengths, and exchange corrections are calculated for the three-particle complex corresponding to an exciton bound to an ionized donor. The results are given as functions of the mass ratio of the electron and hole. Binding of the complex is o...

  15. Liquid-filled ionization chamber temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Franco, L. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)]. E-mail: luciaff@usc.es; Gomez, F. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Iglesias, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pardo, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pazos, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pena, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Zapata, M. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)

    2006-05-10

    Temperature and pressure corrections of the read-out signal of ionization chambers have a crucial importance in order to perform high-precision absolute dose measurements. In the present work the temperature and pressure dependences of a sealed liquid isooctane filled ionization chamber (previously developed by the authors) for radiotherapy applications have been studied. We have analyzed the thermal response of the liquid ionization chamber in a {approx}20 deg. C interval around room temperature. The temperature dependence of the signal can be considered linear, with a slope that depends on the chamber collection electric field. For example, a relative signal slope of 0.27x10{sup -2}K{sup -1} for an operation electric field of 1.67x10{sup 6}Vm{sup -1} has been measured in our detector. On the other hand, ambient pressure dependence has been found negligible, as expected for liquid-filled chambers. The thermal dependence of the liquid ionization chamber signal can be parametrized within the Onsager theory on initial recombination. Considering that changes with temperature of the detector response are due to variations in the free ion yield, a parametrization of this dependence has been obtained. There is a good agreement between the experimental data and the theoretical model from the Onsager framework.

  16. Review Ionizing Radiation In The Environment

    International Nuclear Information System (INIS)

    Hassan, K.M.

    2007-01-01

    Our environment is pervaded by ionizing radiation of natural origin including terrestrial radionuclides and extra-terrestrial sources but man's activities can increase radiation levels by acting on natural sources or by producing artificial radionuclides. The energy released by radionuclides can be measured. The amount of energy generated in our bodies from the radioactive decay of within- body radionuclides is called internal dose. External dose results from gamma rays emitted by terrestrial sources such as the ground, building materials and from extraterrestrial sources. The major contributors to human exposure are radon and its daughters in the air that we breathe. Ionizing radiation can penetrate into matter and thus, causing damage by interacting with the atoms and molecules of the medium. If the medium is living tissue, damage to cells can take place. Very large doses of radiation will result in serious tissue, damage that may lead to death of the organism. Lower doses may also be harmful and do not cause the immediate damage of high doses but instead act to increase the likelihood of developing cancer. So, exposure to ionizing radiation can have health consequences, which is why we are concerned about and, to a large extent, is why this review paper was written. Exposure to ionizing radiation should be kept as minimum as practically possible. People are advised to monitor the concentrations of radon in their houses. In addition, the levels of radionuclides in drinking water should also be monitored in accordance with the guidelines used in the USA

  17. Inner shell ionization by incident nuclei

    International Nuclear Information System (INIS)

    Hansteen, J.M.

    1974-10-01

    The atomic Coulomb excitation process induced by impinging heavy charged particles such as protons, deuterons, α-particles and complex heavy ions is reviewed. Recent experimental and theoretical efforts have led toimproved understanding of the atomic Coulomb excitation as well as to discovery of new types of ionization mechanisms. The following models are mentioned: the Plane Wave Born Approximation (PWBA); theeeeeeeeeeeee modified PWBA model; the Binary Encounter Approximation (BEA); the Semi-Classical Approximation (SCA); the Perturbed-Stationary-State model (PSS). The structure of the SCA model is more thoroughly treated. Experimental results on single Coulomb ionizations of the K-, L-, and M-shells, and of the connected sub-shells by protons are compared with predictions. Most calculations are based on straight line projectile paths and non-relativistic hydrogen-like target electron wave functions. The BEA model and the SCA model seem to work reasonably well for multiple Coulomb ionizations by stripped light ions. Background effects in ion-atom collisions are commented upon. Future aspects of atomic Coulomb excitation by incident nuclei and ions are discussed. The interplay between Coulomb induced processes and united atom phenomena is especially mentioned. The simple ionization models have yielded valuable insights but it is suggested that this branch of collision physics has reached a turning point where new and more advanced and unifying models are needed. (JIW)

  18. Electron impact ionization of Ar8+

    International Nuclear Information System (INIS)

    Defrance, P.; Rachafi, S.; Jureta, J.; Meyer, F.; Chantrenne, S.

    1986-01-01

    Absolute electron impact ionization cross-sections have been measured for the Neon-like Ar 8+ in the energy range from below the threshold for the metastable state to 2500 eV. No contribution of metastable states is observed. The results are well reproduced by the Distorted Wave Born Approximation. 12 refs., 1 fig

  19. Management in the protection from ionizing radiation

    International Nuclear Information System (INIS)

    Radunovic, Miodrag; Nikolic, Krsto; Rakic, Goran

    2008-01-01

    There are numerous types and forms of endangering working and living environment, ranging from natural disasters to nuclear accidents. Challenges of the New Age determined that most of the countries reviewed its strategic decisions in the system of protection from ionizing radiation and nuclear safety and defined in a new way the threats, which could considerably imperil health of the population and national interests as well. Excessive radiation of the population became a serious and actual problem in the era of increasingly mass application of ionizing radiation, especially in medicine. The goal of this work is to reduce the risk through using knowledge and existing experiences, in particular when it comes to ionizing radiation in medicine. Optimization of the protection in radiology actually means an effort to find the compromise between quality information provided by diagnostics procedure and quality effects of therapy procedure on one side and dose of radiation received by patients on the other. Criteria for the quality management in the protection from ionizing radiation used in diagnostic radiology was given by the European Commission: European Guidelines on Quality Criteria for Diagnostic Radiographic Images, EUR, 16260. (author)

  20. Fast Atom Ionization in Strong Electromagnetic Radiation

    Science.gov (United States)

    Apostol, M.

    2018-05-01

    The Goeppert-Mayer and Kramers-Henneberger transformations are examined for bound charges placed in electromagnetic radiation in the non-relativistic approximation. The consistent inclusion of the interaction with the radiation field provides the time evolution of the wavefunction with both structural interaction (which ensures the bound state) and electromagnetic interaction. It is shown that in a short time after switching on the high-intensity radiation the bound charges are set free. In these conditions, a statistical criterion is used to estimate the rate of atom ionization. The results correspond to a sudden application of the electromagnetic interaction, in contrast with the well-known ionization probability obtained by quasi-classical tunneling through classically unavailable non-stationary states, or other equivalent methods, where the interaction is introduced adiabatically. For low-intensity radiation the charges oscillate and emit higher-order harmonics, the charge configuration is re-arranged and the process is resumed. Tunneling ionization may appear in these circumstances. Extension of the approach to other applications involving radiation-induced charge emission from bound states is discussed, like ionization of molecules, atomic clusters or proton emission from atomic nuclei. Also, results for a static electric field are included.

  1. An analytical excitation for an ionizing plasma

    NARCIS (Netherlands)

    Mullen, van der J.J.A.M.; Sijde, van der B.; Schram, D.C.

    1983-01-01

    From an analytical model for the population of high-lying excited levels in ionizing plasmas it appears that the distribution is a superposition of the equilibrium (Saha) value and an overpopulation. This overpopulation takes the form of a Maxwell distribution for free electrons. Experiments for He

  2. Penetration of electronic beams in ionizing media

    International Nuclear Information System (INIS)

    Martiarena, M.L.; Zanete, D.H.; Garibotti, C.R.

    1988-01-01

    It is studied the penetration of an electron beam in an ionizable medium by means of a generalized kinetic equation. This equation is related to elastic collisions, processes of creation and destruction of particles. By integrating numerically the transport equation, it can be evaluated the relative effects of all the processes involved in the evolution of the system. (A.C.A.S.) [pt

  3. Notes on photon assisted field ionization

    International Nuclear Information System (INIS)

    Niu, B.H.C.; Bryant, P.J.

    1979-01-01

    A response to comments by Viswanathan et al (2) on a previous publication(1) by the authors is given. It is contended that the original hypothesis of photon assisted field ionization at metal surfaces correctly explains the results reported in Ref. 1

  4. Propagating discontinuities in ionized porous media

    NARCIS (Netherlands)

    Kraaijeveld, F.

    2009-01-01

    Ionized porous media swell or shrink under changing osmotic conditions. Examples of such materials are shales, clays, hydrogels and tissues. The materials are represented as a multi-phase material consisting of a solid part and a fluid part with fixed charges embedded in the solid matrix and counter

  5. Doses and biological effect of ionizing radiation

    International Nuclear Information System (INIS)

    Hrynkiewicz, A.

    1993-01-01

    The aim of the monograph is to review practical aspects of dosimetry. The work describes basic units which are used in dosimetry and natural as well as industrial sources of ionizing radiation. Information given in the monograph help in assessment of the radiation risk. 8 refs, 15 tabs

  6. Ionization model for nickel-like gold

    International Nuclear Information System (INIS)

    Busquet, M.; Bruneau, J.

    1986-04-01

    Before we build an extensive population model for gold ionized 49 to 52 times, we have studied with a more simple model the effect of accounting for cascades (or dielectronic recombination) and Δn = 0 transitions. These transitions allow some understanding of typical feature of experimental gold spectra

  7. Metrology of ionizing radiations and environmental measurements

    International Nuclear Information System (INIS)

    Nourreddine, Abdel-Mjid

    2008-01-01

    The subject of radiation protection covers all measurements taken by the authorities to ensure protection of the population and its environment against the harmful effects of ionizing radiation. Dosimetry occupies an important place in this field, because it makes it possible to consider and to quantify the risk of using radiations in accordance with the prescribed limits. In this course, we will review the fundamental concepts used in the metrology and dosimetry of ionizing radiations. After classification of ionizing radiations according to their interactions with biological matter, we will present the various quantities and units brought into play and in particular the new operational quantities that are good estimators raising protection standards. They are directly connected to the annual limits of effective dose and of equivalent dose defined in the French regulation relating to the protection of the population and of workers against ionizing radiations. The average natural exposure of the population in France varies between 2 to 2.5 mSv per year, depending on geographic location. It comes principally from three sources: cosmic radiation, radioactive elements contained in the ground and radioactive elements that we absorb when breathing or eating. Radon, which is a naturally occurring radioactive gas, is a public health risk and represents 30% of the exposure. Finally, we will give some applications of dosimetry and environmental measurements developed recently at RaMsEs/IPHC laboratory of Strasbourg. (author)

  8. Chemical protection against ionizing radiation. Final report

    International Nuclear Information System (INIS)

    Livesey, J.C.; Reed, D.J.; Adamson, L.F.

    1984-08-01

    The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references

  9. Several versions of forward gas ionization calorimeter

    International Nuclear Information System (INIS)

    Babintsev, V.V.; Kholodenko, A.G.; Rodnov, Yu.V.

    1994-01-01

    The properties of several versions of a gas ionization calorimeter are analyzed by means of the simulation with the GEANT code. The jet energy and coordinate resolutions are evaluated. Some versions of the forward calorimeter meet the ATLAS requirements. 13 refs., 15 figs., 7 tabs

  10. Roles of ionizing radiation in cell transformation

    International Nuclear Information System (INIS)

    Tobias, C.A.; Albright, N.W.; Yang, T.C.

    1983-07-01

    Earlier the authors described a repair misrepair model (RMR-I) which is applicable for radiations of low LET, e.g., x rays and gamma rays. RMR-II was described later. Here is introduced a mathematical modification of the RMR model, RMR-III, which is intended to describe lethal effects caused by heavily ionizing tracks. 31 references, 4 figures

  11. Long-term effects of ionizing radiation

    International Nuclear Information System (INIS)

    Kaul, Alexander; Burkart, Werner; Grosche, Bernd; Jung, Thomas; Martignoni, Klaus; Stephan, Guenther

    1997-01-01

    This paper approaches the long-term effects of ionizing radiation considering the common thought that killing of cells is the basis for deterministic effects and that the subtle changes in genetic information are important in the development of radiation-induced cancer, or genetic effects if these changes are induced in germ cells

  12. Chemical protection against ionizing radiation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Livesey, J.C.; Reed, D.J.; Adamson, L.F.

    1984-08-01

    The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

  13. Alanine-polymer dosemeter of ionizing radiation

    International Nuclear Information System (INIS)

    Tomasinski, Z.; Mirkowski, K.; Panta, P.; Stachowicz, W.

    1994-01-01

    The method of chemical preparation of alanine-copolymer of ethylene and vinyl acetate has been worked out. The material has been in a form of rods. The content of alanine has not exceeded 30%. The ESR signal of alanine radicals has been detected after exposition to ionizing radiation. The dose-response relationship has been presented

  14. The industrial applications of ionizing radiations

    International Nuclear Information System (INIS)

    1992-10-01

    This report presents all industrial applications of ionizing radiations in France, for food preservation, radiosterilization of drugs, medical materials and cosmetic products, for radiation chemistry of polymers. This report also describes the industrial plants of irradiation (electron, cobalt 60). Finally, it explains the legal and safety aspects

  15. Historical survey of resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Hurst, G.S.

    1984-04-01

    We have recently celebrated the 10th birthday of Resonance Ionization Spectroscopy (RIS), and this seems an appropriate time to review the history of its development. Basically, RIS is a photophysics process in which tunable light sources are used to remove a valence electron from an atom of selected atomic number, Z. If appropriate lasers are used as the light source, one electron can be removed from each atom of the selected Z in the laser pulse. This implies that RIS can be a very efficient, as well as selective, ionization process. In what we normally call RIS, laser schemes are employed which preserve both of these features. In contrast, multiphoton ionization (MPI) is more general, although not necessarily Z selective or very efficient because resonances are often not used. Early research completed in the USSR and described as selective two-step photoionization, employed resonances to ionize the rubidium atom and served to guide work on laser isotope separation. 29 references, 8 figures

  16. Preservation of almonds by ionizing radiation

    International Nuclear Information System (INIS)

    Trabelsi, M.

    1997-01-01

    During two months, a series of experiments was carried out to highlight the effects of preservation by ionizing radiation of a variety of Tunisian almonds. This technique was proved correct for doses less than 1 KGy. Nevertheless, this technique may be harmful to proteins.(author)

  17. Composite scintillators for detection of ionizing radiation

    Science.gov (United States)

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  18. Interaction of ionizing radiation with matter

    International Nuclear Information System (INIS)

    Calisto, Washington

    1994-01-01

    Definition of ionizing radiation,interaction of electrons with matter,physical model of collision,elastic and inelastic collisions,range of electron in matter,interaction of photon with matter.Photoelectric effect , Compton effect,pair production,consideration of interaction of various radiations with soft tissue

  19. Ionization Energy: Implications of Preservice Teachers' Conceptions

    Science.gov (United States)

    Tan, Kim Chwee Daniel; Taber, Keith S.

    2009-01-01

    The results from a study to explore pre-service teachers' understanding of ionization energy, a topic that features in A-level (grade 11 and 12) chemistry courses. in Singapore , is described. A previous study using a two-tier multiple choice diagnostic test has shown that Singapore A-level students have considerable difficulty understanding the…

  20. Theory of multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    Szoeke, A.

    1986-03-01

    A non-perturbative approach to the theory of multiphoton ionization is reviewed. Adiabatic Floquet theory is its first approximation. It explains qualitatively the energy and angular distribution of photoelectrons. In many-electron atoms it predicts collective and inner shell excitation. 14 refs

  1. Dynamics of tunneling ionization using Bohmian mechanics

    Science.gov (United States)

    Douguet, Nicolas; Bartschat, Klaus

    2018-01-01

    Recent attoclock experiments and theoretical studies regarding the strong-field ionization of atoms by few-cycle infrared pulses revealed features that have attracted much attention. Here we investigate tunneling ionization and the dynamics of the electron probability using Bohmian mechanics. We consider a one-dimensional problem to illustrate the underlying mechanisms of the ionization process. It is revealed that in the major part of the below-the-barrier ionization regime, in an intense and short infrared pulse, the electron does not tunnel through the entire barrier, but rather starts already from the classically forbidden region. Moreover, we highlight the correspondence between the probability of locating the electron at a particular initial position and its asymptotic momentum. Bohmian mechanics also provides a natural definition of mean tunneling time and exit position, taking account of the time dependence of the barrier. Finally, we find that the electron can exit the barrier with significant kinetic energy, thereby corroborating the results of a recent study [N. Camus et al., Phys. Rev. Lett. 119, 023201 (2017), 10.1103/PhysRevLett.119.023201].

  2. Ionizing radiation in the education of medicine

    International Nuclear Information System (INIS)

    Ivanova, N.

    2016-01-01

    Physics is a fundamental science that finds its applications in all areas of our lives. Its application in modern medicine is undeniable. In today’s medical practice special attention is dedicated to the use of ionizing radiation. The wide range of modern science and technology offers enormous possibilities for creation and implementation of new equipment using adequate doses of ionizing radiation. For accurate medical diagnostics and effective treatment of patients, this type of equipment must provide the necessary information to the physicians. On the other hand, the physicians should possess enough knowledge in the relative field of medicine. This paper contains information about the knowledge communicated to the students of the graduate program Medical Physics and Biophysics in the discipline Medicine in the first year of graduate study at the Medical University “Prof. Dr. Paraskev Stoyanov” of Varna. Firstly, we discuss the topics in the lectures of these two disciplines, concerning knowledge about ionizing radiation. Secondly, the respective laboratory exercises are described that illustrate the lectures in the graduate programs Medical Physics and Biophysics. Keywords: ionizing radiation, education, medicine, medical physics, biophysics

  3. Circuit for current measures from ionization chambers

    International Nuclear Information System (INIS)

    Mello, F.L.V. de; Oliveira, A.H. de; Rezende, R.S.

    1992-01-01

    The design and the specifications of an ammeters of low cost for small current, IOE-14 Ampere, from ionization chambers or others transducers used in nuclear instrumentation are described. Special attention is given to the integrated electronic components, available in the brazilian market. (C.G.C.)

  4. Ionization of amphiphilic acidic block copolymers.

    Science.gov (United States)

    Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco

    2012-06-28

    The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

  5. Electron Impact Excitation-Ionization of Molecules

    Science.gov (United States)

    Ali, Esam Abobakr A.

    In the last few decades, the study of atomic collisions by electron-impact has made significant advances. The most difficult case to study is electron impact ionization of molecules for which many approximations have to be made and the validity of these approximations can only be checked by comparing with experiment. In this thesis, I have examined the Molecular three-body distorted wave (M3DW) or Molecular four-body distorted wave (M4DW) approximations for electron-impact ionization. These models use a fully quantum mechanical approach where all particles are treated quantum mechanically and the post collision interaction (PCI) is treated to all orders of perturbation. These electron impact ionization collisions play central roles in the physics and chemistry of upper atmosphere, biofuel, the operation of discharges and lasers, radiation induced damage in biological material like damage to DNA by secondary electrons, and plasma etching processes. For the M3DW model, I will present results for electron impact single ionization of small molecules such as Water, Ethane, and Carbon Dioxide and the much larger molecules Tetrahydrofuran, phenol, furfural, 1-4 Benzoquinone. I will also present results for the four-body problem in which there are two target electrons involved in the collision. M4DW results will be presented for dissociative excitation-ionization of orientated D2. I will show that M4DW calculations using a variational wave function for the ground state that included s- and p- orbital states give better agreement to the experimental measurements than a ground state approximated as a product of two 1s-type Dyson orbitals.

  6. Detoxification of snake venom using ionizing radiation

    International Nuclear Information System (INIS)

    Rogero, J.R.; Nascimento, N.

    1995-01-01

    It is generally recognized that energy absorbed by ionizing radiation (gamma rays) can inactivate biological material in tow ways. A direct effects occurs when the primary event, i.e., ionization, is produced in the molecule itself. This is the case when a compound is irradiated in dry state. When a compound is irradiated in a solution, the indirect effect joins the direct. Since water is the most abundant constituent of biological material, it is important to consider the species produced by excitation and ionization of water itself, and the reaction of these species with the target molecules of biological importance. This indirect effect results from the reactions among the studied molecules and the products of radiation interaction with water or other solvents. Highly reactive compounds, the so-called free radicals, which are formed many reactions among themselves, with the dissolved gas, and with other molecules in the solution. With water, the excitation is less important than ionization which is followed within picosecond by the formation of free hydroxyl radicals and hydrated electrons. Alexander and Hamilton showed that irradiation of proteins has revealed damage to aminoacid side chains, production of new groups, splitting of peptide bonds and formation of intramolecular and intermolecular cross-links. With these results it would be possible to use ionizing radiation to change those proteins molecules in order to improve some of their properties according to the necessity. On the other hand, it is recognized that venoms in general are poorly immunogenic, yet fairly toxic. This cause problems because serotherapy is the treatment of choice in snakebite envenomations, and horse antivenom availability is dependent upon. (author)

  7. First successful ionization of Lr (Z = 103) by a surface-ionization technique

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Tetsuya K., E-mail: sato.tetsuya@jaea.go.jp; Sato, Nozomi; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Ooe, Kazuhiro; Miyashita, Sunao; Schädel, Matthias [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kaneya, Yusuke; Nagame, Yuichiro [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512 (Japan); Osa, Akihiko [Department of Research Reactor and Tandem Accelerator, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Ichikawa, Shin-ichi [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Stora, Thierry [ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); Kratz, Jens Volker [Institut für Kernchemie, Universität Mainz, D-55099 Mainz (Germany)

    2013-02-15

    We have developed a surface ionization ion-source as part of the JAEA-ISOL (Isotope Separator On-Line) setup, which is coupled to a He/CdI{sub 2} gas-jet transport system to determine the first ionization potential of the heaviest actinide lawrencium (Lr, Z = 103). The new ion-source is an improved version of the previous source that provided good ionization efficiencies for lanthanides. An additional filament was newly installed to give better control over its operation. We report, here, on the development of the new gas-jet coupled surface ion-source and on the first successful ionization and mass separation of 27-s {sup 256}Lr produced in the {sup 249}Cf + {sup 11}B reaction.

  8. Absorbed dose measurement by using tissue equivalent ionization chamber (pair ionization chamber) in the Yayoi reactor

    International Nuclear Information System (INIS)

    Sasuga, N.; Okamura, K.; Terakado, T.; Mabuchi, Y.; Nakagawa, T.; Sukegawa, Toshio; Aizawa, C.; Saito, I.; Oka, Yoshiaki

    1998-01-01

    Each dose rate of neutron and gamma ray in the thermal column of the Yayoi reactor, in which an epithermal neutron field will be used for the boron neutron capture therapy, was measured by using a tissue equivalent ionization chamber and a graphite chamber. The tissue equivalent ionization chamber has some response to both neutron and gamma ray, but the graphite chamber has a few response to the neutron, so called pair ionization chamber method. The epithermal neutron fluxes of the thermal column were calculated by ANISN (one dimensional neutron-gamma transport code). A measured value for gamma dose rate by the pair ionization chamber agrees relevantly with a calculated result. For neutron dose rate, however, the measured value was too much small in comparison with the calculated result. The discrepancy between the measured value and the calculated result for neutron dose rate is discussed in detail in the report. (M. Suetake)

  9. Ionization of xenon by electrons: Partial cross sections for single, double, and triple ionization

    International Nuclear Information System (INIS)

    Mathur, D.; Badrinathan, C.

    1987-01-01

    High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the Xe + data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms

  10. Estimation of the contribution of ionization and excitation to the lethal effect of ionizing radiation

    International Nuclear Information System (INIS)

    Petin, V.G.; Komarov, V.P.

    1982-01-01

    A simple theoretical model is proposed for estimating the differential contribution of ionization and excitation to the lethal effect of ionizing radiation. Numerical results were obtained on the basis of published experimental data on the ability of bacterial cells Escherichia coli to undergo photoreactivation of radiation-induced damage. It was shown that inactivation by excitation may be highly significant for UV-hypersensitive cells capable of photoreactivation; inactivation by excitation increased with the energy of ionizing radiation and the volume of irradiated suspensions. The data are in qualitative agreement with the assumption of a possible contribution of the UV-component of Cerenkov radiation to the formation of excitations responsible for the lethal effect and the phenomenon of photoreactivation after ionizing radiation. Some predictions from the model are discussed. (orig.)

  11. Measurement of the first ionization potential of astatine by laser ionization spectroscopy

    Science.gov (United States)

    Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

    2013-01-01

    The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

  12. Application of ionizing radiation to preservation of mushrooms

    International Nuclear Information System (INIS)

    Smierzchalska, K.; Gubrynowicz, E.

    1979-01-01

    The influence of ionizing radiation on prolongation of preservation time and quality of mushrooms is discussed. Some numerical data are cited. The influence of ionizing radiation on growth rate and physiological processes is also presented. (A.S.)

  13. Fully differential cross sections for heavy particle impact ionization

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2009-11-15

    We describe a procedure for extracting fully differential ionization cross sections from an impact parameter coupled pseudostate treatment of the collision. Some examples from antiproton impact ionization of atomic Hydrogen are given.

  14. To the calculation of energy resolution of ionization calorimeter

    International Nuclear Information System (INIS)

    Uchajkin, V.V.; Lagutin, A.A.

    1976-01-01

    The question of energy resolution of the ionization calorimeter is considered analytically. A method is discussed for calculating the probability characteristics (mean value and dispersion) of energy losses of an electron-photon shower by ionization in the calorimeter volume

  15. Single and double ionization of gallium by electron impact

    Indian Academy of Sciences (India)

    Electron impact single and double ionization cross sections of gallium have been calcu- ... The experimental data on single ionization have been compared with the empirical and ..... and multiplication sign curve (¢¢¢) represent present.

  16. Ionization of highly excited atoms by atomic particle impact

    International Nuclear Information System (INIS)

    Smirnov, B.M.

    1976-01-01

    The ionization of a highly excited atom by a collision with an atom or molecule is considered. The theory of these processes is presented and compared with experimental data. Cross sections and ionization potential are discussed. 23 refs

  17. Ionizing radiation in earth's atmosphere and in space near earth.

    Science.gov (United States)

    2011-05-01

    The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in air travel and in : commercial human space travel. This report addresses one of these hazards ionizing radiation. : Ionizing radiation is a subatomic p...

  18. On possible structures of transverse ionizing shock waves

    International Nuclear Information System (INIS)

    Liberman, M.A.; Velikovich, A.L.

    1978-01-01

    The possible structures of ionizing shock waves propagating in gases across the magnetic field are investigated taking account of both ionization kinetics and the non-isothermality of the plasma which is formed within the shock front. It is shown that a definite factor in shaping the structure of the transverse ionizing shock wave is photo-ionization of the neutral gas across the front. The paper includes a study of the evolution of the transverse ionizing shock front with regard to photo-ionization, disclosing that a stable stationary shock structure emerges only in boundary conditions which are close to magnetohydrodynamic ones, i.e. upsilon 1 H 1 = upsilon 2 H 2 . In the case of strong transverse ionizing shock waves, when the flux of ionizing radiation across the front is great, the shock structure is obviously magnetohydrodynamic. (author)

  19. The theory of ionizing shock waves in a magnetic field

    International Nuclear Information System (INIS)

    Liberman, M.A.; Velikovich, A.L.

    1981-01-01

    The general theory of ionizing shock waves in a magnetic field is constructed. The theory takes into account precursor ionization of a neutral gas ahead of the shock wave front, caused by photo-ionization, as well as by the impact ionization with electrons accelerated by a transverse electric field induced by the shock front in the incident flow of a neutral gas. The concept of shock wave ionization stability, being basic in the theory of ionizing shock waves in a magnetic field, is introduced. The ionizing shock wave structures are shown to transform from the GD regime at a low shock velocity to the MHD regime at an enhanced intensity of the shock wave. The abruptness of such a transition is determined by precursor photo-ionization. (author)

  20. Ionization dual-zone static detector having single radioactive source

    International Nuclear Information System (INIS)

    Ried, L. Jr.; Wade, A.L.

    1977-01-01

    This ionization detector or combustion product detector includes a single radioactive source located in an ionization chamber, and the ionization chamber includes portions comprising a reference zone and a signal zone. Electrical circuitry connected to the reference and signal zones provides an output signal directly related to changes in voltages across the signal zone in relation to the amount of particulates of combustion present in the ionization chamber

  1. Apparatus for reading and recharging condenser ionization chambers

    International Nuclear Information System (INIS)

    McCall, R.C.

    1977-01-01

    A metering circuit for a condenser ionization chamber is disclosed for simultaneously recharging the ionization chamber and reading out the amount of charge required to recharge the chamber. During the recharging process, the amount of charge necessary to recharge the ionization chamber capacitor is placed on an integrating capacitor in the metering apparatus. The resultant voltage across the integrating capacitor is a measure of the radiation to which the ionization chamber was exposed. 9 claims, 1 figure

  2. Ionizing energy in food processing and pest control. 1. Wholesomeness of food treated with ionizing energy

    International Nuclear Information System (INIS)

    Wierbicki, Eugen

    1986-01-01

    Congressional concerns about the use of ionizing energy for food preservation and to control pests in food products for export and domestic use promoted the preparation of this report by a special task force of the Council for Agricultural Science and Technology (CAST). An overview surveys research conducted on the toxicological safety, nutritional quality, and microbiological safety of foods treated with ionizing energy. Background information is provided on various types of electromagnetic radiation, effects of ionizing energy level and dose, sources of natural background radiation and induced radioactivity, and the nature and safety of various radiolytic products. Objectives, methodologies, and problems associated with feeding studies of toxicological safety are outlined; results of scientific studies, U.S. government wholesomeness studies, and international feeding studies are summarized. Studies on the nutritional value of food products processed using ionized energy have examined the effects of ionizing energy on 1) composite diets, 2) carbohydrates, 3) fats, 4) proteins and amino acids, 5) vitamins (potatoes, onions, fruits, meat, seafood, cereals, vegetables, dairy products, oils), 6) antivitamins, and 7) minerals. The report concludes that currently available scientific evidence indicates that foods exposed to ionizing energy under the conditions proposed for commercial application are 1) wholesome (safe to eat) and 2) comparable in nutritional adequacy to fresh or conventionally processed foods

  3. State and trends of ionization gas analysis. 1

    International Nuclear Information System (INIS)

    Leonhardt, J.W.; Grosse, H.J.; Popp, P.

    1980-01-01

    The ionization gas analysis makes use of the fact that the ionization-induced conductivity of gases and gas mixtures changes with the composition of such mixtures. A general description is given of ionization detectors based on this principle and theory, properties, and main fields of application of electron capture detectors are discussed

  4. Measurement of indoor background ionizing radiation in some ...

    African Journals Online (AJOL)

    Certain types of building materials are known to be radioactive. Exposure to indoor ionizing radiation like exposure to any other type of ionizing radiation results in critical health challenges. Measurement of the background ionizing radiation profile within the Chemistry Research Laboratory and Physics Laboratory III all of ...

  5. Six categories of ionizing radiation quantities practical in various fields

    International Nuclear Information System (INIS)

    Zheng Junzheng; Zhuo Weihai

    2011-01-01

    This paper is the part of review on the evolvement of the systems for ionizing radiation quantities and units. In the paper, for better understanding and correct use of the relevant quantities of ionizing radiation, the major ionizing radiation quantities in various fields are divided into six categories. (authors)

  6. Method and apparatus to monitor a beam of ionizing radiation

    Science.gov (United States)

    Blackburn, Brandon W.; Chichester, David L.; Watson, Scott M.; Johnson, James T.; Kinlaw, Mathew T.

    2015-06-02

    Methods and apparatus to capture images of fluorescence generated by ionizing radiation and determine a position of a beam of ionizing radiation generating the fluorescence from the captured images. In one embodiment, the fluorescence is the result of ionization and recombination of nitrogen in air.

  7. Health consequences of ionizing radiation exposure

    International Nuclear Information System (INIS)

    Dalci, D.; Dorter, G.; Guclu, I.

    2004-01-01

    The increasing use of ionizing radiations all over the world induces an ever increasing interest of the professionals as well as of the whole society in health protection and the risk due to these practices. Shortly after its discovery, it was recognized that ionizing radiation can have adverse health effects and knowledge of its detrimental effects has accumulated. The fact that ionizing radiation produces biological damage has been known for many years. The biological effects of ionizing radiation for radiation protection considerations are grouped into two categories: The deterministic and the stochastic ones. Deterministic radiation effects can be clinically diagnosed in the exposed individual and occur when above a certain 'threshold' an appropriately high dose is absorbed in the tissues and organs to cause the death of a large number of cells and consequently to impair tissue or organ functions early after exposure. A clinically observable biological effect (Acute Radiation Syndromes, ARS) that occurs days to months after an acute radiation dose. ARS is a complex of acute injury manifestations that occur after a sufficiently large portion of a person's body is exposed to a high dose of ionizing radiation. Such irradiation initially injures all organs to some extent, but the timing and extent of the injury manifestations depend upon the type, rate, and dose of radiation received. Stochastic radiation effects are the chronic effects of radiation result from relatively low exposure levels delivered over long periods of time. These are sort of effects that might result from occupational exposure, or to the background exposure levels (includes radioactive pollution). Such late effects might be the development of malignant (cancerous) disease and of the hereditary consequences. These effects may be observed many years after the radiation exposure. There is a latent period between the initial radiation exposure and the development of the biological effect. In this

  8. The study of the effects of ionizing and non-ionizing radiations on birth weight of newborns to exposed mothers

    OpenAIRE

    Mortazavi, S. M. J.; Shirazi, K. R.; Mortazavi, G.

    2013-01-01

    Objectives: Life evolved in an environment filled with a wide variety of ionizing and non-ionizing radiation. It was previously reported that medical exposures to pregnant women increases the risk of low birth weight. This study intends to investigate the relationship between exposure to ionizing and non-ionizing radiation and the risk of low birth weight. Materials and Methods: One thousand two hundred mothers with their first-term labor (vaginal or cesarean) whose newborns? history had been...

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

    International Nuclear Information System (INIS)

    Zastrow, Jordan; Oey, M. S.; Veilleux, Sylvain; McDonald, Michael

    2013-01-01

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

  10. To manage the ionizing radiations risks

    International Nuclear Information System (INIS)

    Metivier, H.; Romerio, F.

    2000-01-01

    Mister Romerio's work tackles the problem of controversy revealed by the experts in the field of estimation and management of ionizing radiations risks. The author describes the three paradigms at the base of the debate: the relationship without threshold (typified by the ICRP and its adepts), these ones that think that low doses risks are overestimated ( Medicine Academia for example) or that ones that believe that dose limits are too severe and induce unwarranted costs; then that ones that think that these risks are under-estimated and limits should be more reduced, even stop these practices that lead to public exposure to ionizing radiations. The author details the uncertainties about the risk estimations, refreshes the knowledge in radiation protection with the explanations of the different paradigms. At the end a table summarize the positions of the three paradigms

  11. Atomic resonances above the total ionization energy

    International Nuclear Information System (INIS)

    Doolen, G.

    1975-01-01

    A rigorous result obtained using the theory associated with dilatation analytic potentials is that by performing a complex coordinate rotation, r/subj/ → r/subj/e/subi//sup theta/, on a Hamiltonian whose potential involves only pairwise Coulombic interactions, one can show that when theta = π/2, no complex eigenvalues (resonances) appear whose energies have a real part greater than the total ionization energy of the atomic system. This appears to conflict with experimental results of Walton, Peart, and Dolder, who find resonance behavior above the total ionization energy of the H -- system and also the theoretical stabilization results of Taylor and Thomas for the same system. A possible resolution of this apparent conflict is discussed and a calculation to check its validity is proposed

  12. Two-colour ionization of hydrogen

    International Nuclear Information System (INIS)

    Fifirig, M.; Cionga, A.; Florescu, V.

    1995-01-01

    The studies of different radiative processes in hydrogen continue to be of interest, as they provide a comparison basis for calculations done on many electron atoms. We consider the case of the hydrogen atom interacting simultaneously with two electromagnetic fields of incommensurable frequencies. Our attention is focused on three-photon transitions between the ground state and a final state in the continuum. The existence of compact forms for the first and second-order corrections to the wave functions of a Coulomb-field electron due to the electromagnetic field leads to compact results for the matrix element of the transitions. Numerical results are presented for the total ionization rate and the angular distribution of ejected electrons in a regime in which none of the fields is able to ionize alone the atom. (author)

  13. Atmospheric Ionizing Radiation and Human Exposure

    Science.gov (United States)

    Wilson, John W.; Mertens, Christopher J.; Goldhagen, Paul; Friedberg, W.; DeAngelis, G.; Clem, J. M.; Copeland, K.; Bidasaria, H. B.

    2005-01-01

    Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere near the Earth s surface tend to be dominated by the terrestrial radioisotopes. especially along the coastal plain and interior low lands, and have only minor contributions from neutrons (11 percent). The world average is substantially larger but the high altitude cities especially have substantial contributions from neutrons (25 to 45 percent). Understanding the world distribution of neutron exposures requires an improved understanding of the latitudinal, longitudinal, altitude and spectral distribution that depends on local terrain and time. These issues are being investigated in a combined experimental and theoretical program. This paper will give an overview of human exposures and describe the development of improved environmental models.

  14. The toxic effects of ionizing radiations

    International Nuclear Information System (INIS)

    Draghita Payet, A.C.

    2006-06-01

    The sources of radiations to which the human body is subjected are of natural or artificial origin and the irradiation of the human body can take place either by internal or external way. The ionizing radiations act at several levels of the human body, the main thing being the molecule of DNA. The ionizing radiations have no specificity, the effects on the human body can be: somatic, genetic or hereditary, teratogen. In the case of a human being irradiation, we proceed to the diagnosis and to the treatment of the irradiated person, however, to decrease the incidence of injuries we use the radiation protection. The treatment if necessary will be established according to the irradiation type. (N.C.)

  15. Chromosomal instability induced by ionizing radiation

    International Nuclear Information System (INIS)

    Morgan, W.F.; Marder, B.A.; Day, J.P.

    1995-01-01

    There is accumulating evidence indicating genomic instability can manifest multiple generations after cellular exposure to DNA damaging agents. For instance, some cells surviving exposure to ionizing radiations show delayed reproductive cell death, delayed mutation and / or delayed chromosomal instability. Such instability, especially chromosome destabilization has been implicated in mutation, gene amplification, cellular transformation, and cell killing. To investigate chromosomal instability following DNA damage, we have used fluorescence in situ hybridization to detect chromosomal rearrangements in a human/hamster somatic hybrid cell line following exposure to ionizing radiation. Delayed chromosomal instability was detected when multiple populations of uniquely arranged metaphases were observed in clonal isolates raised from single cells. The relationship between delayed chromosomal destabilization and other endpoints of genomic instability, namely; delayed mutation and gene amplification will be discussed, as will the potential cytogenetic and molecular mechanisms contributing to delayed chromosomal instability

  16. Radiobiology: Biologic effects of ionizing radiations

    International Nuclear Information System (INIS)

    Held, K.D.

    1987-01-01

    The biologic effects after exposure to ionizing radiation, such as cell death or tissue injury, result from a chain of complex physical, chemical, metabolic, and histologic events. The time scale of these radiation actions spans many orders of magnitude. The physical absorption of ionizing radiation occurs in about 10 -18 s, while late carcinogenic and genetic effects are expressed years or even generations later. Collectively, these effects form the science of radiobiology. Many of the concepts discussed in this chapter have been developed through the study of effects generated in tissues by external radiation sources, but they apply generally and often specifically to internally distributed radiopharmaceuticals which form the central topic of this book

  17. Atmospheric Ionizing Radiation and Human Exposure

    Science.gov (United States)

    Wilson, J. W.; Goldhagen, P.; Friedberg, W.; DeAngelis, G.; Clem, J. M.; Copeland, K.; Bidasaria, H. B.

    2004-01-01

    Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere near the Earth s surface tend to be dominated by the terrestrial radioisotopes especially along the coastal plain and interior low lands and have only minor contributions from neutrons (11 percent). The world average is substantially larger but the high altitude cities especially have substantial contributions from neutrons (25 to 45 percent). Understanding the world distribution of neutron exposures requires an improved understanding of the latitudinal, longitudinal, altitude and spectral distribution that depends on local terrain and time. These issues are being investigated in a combined experimental and theoretical program. This paper will give an overview of human exposures and describe the development of improved environmental models.

  18. Communication: Electron ionization of DNA bases

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, M. A.; Krishnakumar, E., E-mail: ekkumar@tifr.res.in

    2016-04-28

    No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space.

  19. Shock Wave Dynamics in Weakly Ionized Plasmas

    Science.gov (United States)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  20. Propagation of an ionizing surface electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Boev, A.G.; Prokopov, A.V.

    1976-11-01

    The propagation of an rf surface wave in a plasma which is ionized by the wave itself is analyzed. The exact solution of the nonlinear Maxwell equations is discussed for the case in which the density of plasma electrons is an exponential function of the square of the electric field. The range over which the surface wave exists and the frequency dependence of the phase velocity are found. A detailed analysis is given for the case of a plasma whose initial density exceeds the critical density at the wave frequency. An increase in the wave amplitude is shown to expand the frequency range over which the plasma is transparent; The energy flux in the plasma tends toward a certain finite value which is governed by the effective ionization field.

  1. Ionizing-radiation warning - Supplementary symbol

    International Nuclear Information System (INIS)

    2007-01-01

    This International Standard specifies the symbol to warn of the presence of a dangerous level of ionizing radiation from a high-level sealed radioactive source that can cause death or serious injury if handled carelessly. This symbol is not intended to replace the basic ionizing radiation symbol [ISO 361, ISO 7010:2003, Table 1 (Reference number W003)], but to supplement it by providing further information on the danger associated with the source and the necessity for untrained or uninformed members of the public to stay away from it. This symbol is recommended for use with International Atomic Energy Agency (IAEA) Category 1, 2, and 3 sealed radioactive sources. These sources are defined by the IAEA as having the ability to cause death or serious injuries. The paper informs about scope, shape, proportions and colour of the symbol, and application of the symbol. An annex provides the technical specifications of the symbol

  2. Single and multiple ionization of sulfur atoms by electron impact

    International Nuclear Information System (INIS)

    Ziegler, D.L.

    1982-01-01

    Laboratory measurements of the cross sections for single, double, triple, and quadruple ionization of sulfur atoms by electron impact are presented for collision energies from threshold to 500 eV. The cross sections for single ionization of sulfur are measured relative to those of several elements whose absolute cross sections for single ionization are known. Cross sections for each multiple ionization process are then measured relative to those for single ionization. The configuration and operation of the apparatus for these measurements are described. The possible effects of excited sulfur reactants are examined, and the reported cross sections are felt to be characteristic of ground state sulfur atoms

  3. Tumorigenic and tumoricidal actions of ionizing radiations

    International Nuclear Information System (INIS)

    Sanders, C.L.; Kathren, R.L.

    1983-01-01

    The book is divided into two approximately equal parts. The first four chapters are relatively lengthy and cover the basic principles of radiation biology, carcinogenesis and therapy, along with a brief introduction to radiological physics to orient the reader without background in this specialized related discipline. The remainder consists of twenty-four relatively brief chapters, each covering the radiation biology of a specific organ, tissue, or systems tissues, with emphasis on the tumorigenic and tumoricidal action of ionizing radiations

  4. Cataracts induced by microwave and ionizing radiation

    International Nuclear Information System (INIS)

    Lipman, R.M.; Tripathi, B.J.; Tripathi, R.C.

    1988-01-01

    Microwaves most commonly cause anterior and/or posterior subcapsular lenticular opacities in experimental animals and, as shown in epidemiologic studies and case reports, in human subjects. The formation of cataracts seems to be related directly to the power of the microwave and the duration of exposure. The mechanism of cataractogenesis includes deformation of heat-labile enzymes, such as glutathione peroxide, that ordinarily protect lens cell proteins and membrane lipids from oxidative damage. Oxidation of protein sulfhydryl groups and the formation of high-molecular-weight aggregates cause local variations in the orderly structure of the lens cells. An alternative mechanism is thermoelastic expansion through which pressure waves in the aqueous humor cause direct physical damage to the lens cells. Cataracts induced by ionizing radiation (e.g., X-rays and gamma rays) usually are observed in the posterior region of the lens, often in the form of a posterior subcapsular cataract. Increasing the dose of ionizing radiation causes increasing opacification of the lens, which appears after a decreasing latency period. Like cataract formation by microwaves, cataractogenesis induced by ionizing radiation is associated with damage to the lens cell membrane. Another possible mechanism is damage to lens cell DNA, with decreases in the production of protective enzymes and in sulfur-sulfur bond formation, and with altered protein concentrations. Until further definitive conclusions about the mechanisms of microwaves and ionizing radiation induced cataracts are reached, and alternative protective measures are found, one can only recommend mechanical shielding from these radiations to minimize the possibility of development of radiation-induced cataracts. 74 references

  5. HIGH-TEMPERATURE IONIZATION IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Desch, Steven J. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Turner, Neal J. [Jet Propulsion Laboratory, Mail Stop 169-506, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2015-10-01

    We calculate the abundances of electrons and ions in the hot (≳500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains’ work functions. The charged species’ abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks’ dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the “short-circuit” instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters.

  6. Genetic variation in resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Ayala, F.J.

    1991-01-01

    We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population ''null'' (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD ''null'' allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele

  7. Food ionization: principles, nutritional aspects and detection

    International Nuclear Information System (INIS)

    Raffi, J.

    1992-01-01

    This document reviews the possible applications of ionizing radiations in the food industry, pointing out the principles of the treatment and its consequences on the nutritionnal value of the product. The last part gives the present status of the researches about the identification of irradiated foodstuffs and of the concerted action sponsored by the Community Bureau of Reference from the Commission of the European Communities

  8. About particular use of ionizing radiations

    International Nuclear Information System (INIS)

    2001-01-01

    Different uses of ionizing radiations are reviewed: tracers techniques, nuclear gauges, dating by carbon 14, silica doping, use of gamma irradiation for the density measurement in civil engineering, use of a electron capture detector to study by gas chromatography chlorinated contaminants in environment, neutron activation as environmental gauge, analysis of lead in paint and pollutants in ground and dusts, help for work of art valuation by x spectrometry. (N.C.)

  9. Ionizing radiation and photosynthetic ability of cyanobacteria

    International Nuclear Information System (INIS)

    Agarwal, Rachna; Sainis, Jayashree K.

    2006-01-01

    Unicellular photoautotrophic cyanobacteria, Anacystis nidulans when exposed to lethal dose of 1.5 kGy of 60 Co γ- radiation (D 10 = 257.32 Gy) were as effective photosynthetical as unirradiated controls immediately after irradiation although level of ROS was higher by several magnitudes in these irradiated cells. The results suggested the preservation of the functional integrity of thylakoids even after exposure to lethal dose of ionizing radiation. (author)

  10. Design of an ionization diffusion chamber detector

    International Nuclear Information System (INIS)

    Sugiarto, S.

    1976-01-01

    Prototype of an Ionization Diffusion Chamber detector has been made. It is a silindrical glass, 20 cm in diameter, 13,5 cm in height, air gas filled, operated at room pressure and room temperature at the top of this instrument while for the box temperature dry ice (CO 2 solid) temperature is used. This detector is ready for seeing alpha and beta particle tracks. (author)

  11. Excitation mechanisms in singly ionized krypton laser

    International Nuclear Information System (INIS)

    El-Sherbini, Th.M.

    1982-01-01

    Lifetimes for the low lying 4p 4 4d and 4p 4 5s levels of singly ionized krypton laser are calculated, taking into account configuration interaction effects. The results show that some of these levels are metastable. They also suggest a two step excitation from the ground state of the ion (or the atom) to the upper 4p 4 5p laser levels involving some intermediate metastable states as a possible excitation mechanism. (author)

  12. The electron-atom ionization problem

    International Nuclear Information System (INIS)

    McCarthy, I.E.

    1995-02-01

    Methods of calculating electron-atom ionization as a three-body problem with Coulomb boundary conditions are considered. In the absence of a fully-valid computational method for a time-independent experiment the approximation is made that the incident electron experiences a screened potential. Approximations involving a final state that obeys the three-body Coulomb boundary condition are compared with the distorted-wave Born approximation and the convergent close-coupling method. 24 refs., 6 figs

  13. Ionization photophysics and spectroscopy of cyanoacetylene

    International Nuclear Information System (INIS)

    Leach, Sydney; Champion, Norbert; Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François; Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin

    2014-01-01

    Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC 3 N involves new aspects and new assignments of the vibrational components to excitation of the A 2 Σ + and B 2 Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B 2 Π state of HC 3 N + . A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C 2 Σ + state of HC 3 N + at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised

  14. Ionization photophysics and spectroscopy of cyanoacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Leach, Sydney; Champion, Norbert [LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon (France); Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François [Synchrotron SOLEIL, L’Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex (France); Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin [LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil (France)

    2014-05-07

    Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC{sub 3}N involves new aspects and new assignments of the vibrational components to excitation of the A{sup 2}Σ{sup +} and B{sup 2}Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B{sup 2}Π state of HC{sub 3}N{sup +}. A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C{sup 2}Σ{sup +} state of HC{sub 3}N{sup +} at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.

  15. Liquid ionization calorimetry: review and preview

    International Nuclear Information System (INIS)

    Fabjan, C.W.

    1995-01-01

    The experimental requirements at existing and planned accelerators, and new facilities for underground or space-borne experimentation have stimulated a wide-ranging R and D programme in liquid ionization calorimetry. Precision sampling calorimetry is approaching ''crystal'' energy resolution whilst their rate capabilities will be able to cope with the highest LHC luminosities. (Quasi)-homogeneous noble-liquid calorimeters are under construction or in the planning stage to address some of the most fundamental physics questions. (orig.)

  16. Mutation induction in plants by ionizing radiation

    International Nuclear Information System (INIS)

    1985-01-01

    This training film deals with the use of x-rays, gamma rays and fast neutrons for mutation induction in plants. Specific features of different types of ionizing radiation and of biological materials are outlined and methods demonstrated which control modifying factors and warrant an efficient physical mutagenesis. The first step of mutation breeding aims at an enhanced level of genetic variation which forms the basis for mutant selection and use in plant breeding

  17. HIGH-TEMPERATURE IONIZATION IN PROTOPLANETARY DISKS

    International Nuclear Information System (INIS)

    Desch, Steven J.; Turner, Neal J.

    2015-01-01

    We calculate the abundances of electrons and ions in the hot (≳500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains’ work functions. The charged species’ abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks’ dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the “short-circuit” instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters

  18. Multiphoton ionization processes in strong laser

    International Nuclear Information System (INIS)

    Krstic, P.

    1982-01-01

    Multiphoton ionization of hydrogen in ultrastrong laser fields is studied. The previous calculations of this process yield differing result for the transition rate. We show the relations between them and difficulties with each of them. One difficulty is that the finite spatial and time extent of the laser field has been omitted. It is also found that a laser field, which is sufficiently intense to be labeled ultrastrong, makes the electron move relativistically so that it becomes necessary to use Volkov states to describe the electron in the laser field. The transition rate is obtained, using a CO laser as an example, and it is found that the transition rate rises as the laser intensity rises. This is a consequence of the use of relativistic kinematics and is not true nonrelativistically. We also discuss the multiple peaks observed in the energy spectrum of electrons resulting from multiphoton ionization of atoms by lasers. When the laser intensity is large enough for the ponderomotive force to result in appreciable broading of the peaks we show the shape of the broadened peaks contains useful information. We show that the multiphoton ionization probability as a function of laser intensity can be obtained but that the free-free cross sections, which are in principle also obtainable, are probably not obtainable in practice. Finally, we describe the theory of the absorption of more than minimum numbers of photons needed to ionize an atom by an intense laser. The basic approximation used is that the atom is adiabatically deformed by the laser and an impulsive interaction then results in multiphoton absorption. In our first calculation we allow only one resonant excited state to be included in the adiabatic deformation. In our second we also allow the lowest energy continuum to be included. The two results are then compared

  19. Alloy nanoparticle synthesis using ionizing radiation

    Science.gov (United States)

    Nenoff, Tina M [Sandia Park, NM; Powers, Dana A [Albuquerque, NM; Zhang, Zhenyuan [Durham, NC

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  20. Color-indicator dosimeter for ionizing radiation

    International Nuclear Information System (INIS)

    Panchenkov, G.M.; Kozlov, L.L.; Molin, A.A.; Ershova, Z.F.; Mikhailov, L.M.; Juzvyak, A.G.; Valitov, R.B.; Churov, V.P.; Grinev, M.P.

    1980-01-01

    Colorimetric dosimeter of ionizing radiation, containing 70-100 w % of a thermoplastic polymer, 10-40 w. % of a softener, 0.5-3.0 w. % of stabilizer and two dyes compatible with the polymer is designed. The first dye is chosen among zanthene- polymethine- or pyrazolon dyes, while the other is a triarylmethane- indigo- thiazine- indophenol- indiamine- or indaniline dye. (E.G.)

  1. Genetic and somatic effects of ionizing radiation

    International Nuclear Information System (INIS)

    1986-01-01

    This is the ninth substantive report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) to the General Assembly. This report contains reviews on three special topics in the field of biological effects of ionizing radiation that are among those presently under consideration by the Committee: genetic effects of radiation, dose-response relationships for radiation-induced cancer and biological effects of pre-natal irradiation

  2. Evolution of envelope solitons of ionization waves

    International Nuclear Information System (INIS)

    Ohe, K.; Hashimoto, M.

    1985-01-01

    The time evolution of a particle-like envelope soliton of ionization waves in plasma was investigated theoretically. The hydrodynamic equations of one spatial dimension were solved and the nonlinear dispersion relation was derived. For the amplitude of the wave the nonlinear Schroedinger equation was derived. Its soliton solution was interpreted as the envelope soliton which was experimentally found. The damping rate of the envelope soliton was estimated. (D.Gy.)

  3. Objectives and functions of ionizing radiation metrology

    International Nuclear Information System (INIS)

    Rothe, H.

    1981-01-01

    Proceeding from the fundamental objectives of ionizing radiation metrology, the main tasks of metrological research and assurances of accurate measurements in dosimetry and activity determination are summarized. With a view to the technical performance of these tasks the state-of-the-art and the trends in reproduction and dissemination of dosimetric and activity units are outlined. Problems are derived that should be solved within the framework of the CMEA Standing Commissions on Standardization and on the Peaceful Uses of Atomic Energy. (author)

  4. Protection against Ionizing Radiation, No. 1420

    International Nuclear Information System (INIS)

    1978-01-01

    This publication is a compilation of national legislative and regulatory provisions on radiation protection in force on 15 November 1978. In addition to the in extenso texts on the subject, only the relevant provisions in laws and regulations with a more general scope have been reproduced. This comprehensive compilation expands and updates a previous collection by the Official Gazette of the French Republic which covered only decrees and orders on the protection of workers against the hazards of ionizing radiation. (NEA) [fr

  5. Bio-dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    Hadjidekova, V.; Kristova, R.; Stainova, A.; Deleva, S.; Popova, L.; Georgieva, D.

    2013-01-01

    Full text: Introduction: The impact of ionizing radiation in medical, occupational and accidental human exposure leads to adverse side effects such as increased mortality and carcinogenesis. Information about the level of absorbed dose is important for risk assessment and for implementation of appropriate therapy. In most cases of actual or suspected exposure to ionizing radiation biological dosimetry is the only way to assess the absorbed dose. What you will learn: In this work we discuss the methods for biodosimetry and technological developments in their application in various emergency situations. The application of biological dosimetry and assessment of the influence of external factors in the conduct of epidemiological studies of radiation effects in protracted low-dose ionizing radiation on humans is presented. Discussion: The results of cytogenetic analysis and biological evaluation of absorbed dose based on the analysis of dicentrics in peripheral blood lymphocytes of five people injured in a severe radiation accident in Bulgaria in 2011 are presented. The assessed individual doses of the injured persons are in the range of 1.2 to 5,2 Gy acute homogeneous irradiation and are in line with the estimates of international experts. Conclusion: An algorithm to conduct a biological assessment of the dose in limited radiation accidents and in large scale radiation accidents with large number irradiated or suspected for exposure persons is proposed

  6. Influence of ionizing radiation on human body

    Directory of Open Access Journals (Sweden)

    Zygmunt Zdrojewicz

    2016-06-01

    Full Text Available This article describes positive and negative aspects of ionizing radiation and its effects on human body. Being a part of various medical procedures in medicine, ionising radiation has become an important aspect for both medical practitioners and patients. Commonly used in treatment, diagnostics and interventional radiology, its medical usage follows numerous rules, designed to reduce excessive exposure to ionizing radiation. Its widespread use makes it extremely important to research and confirm effects of various doses of radiation on patients of all ages. Two scientific theories, explaining radiation effects on human organism, stand in contrast: commonly accepted LNT-hypothesis and yet to be proven hormesis theory. Despite the fact that the current radiation protection standards are based on the linear theory (LNT-hypothesis, the hormesis theory arouses more and more interest, and numerous attempts are made to prove its validity. Further research expanding the knowledge on radiation hormesis can change the face of the future. Perhaps such researches will open up new possibilities for the use of ionizing radiation, as well as enable the calculation of the optimal and personalised radiation dose for each patient, allowing us to find a new “golden mean”. The authors therefore are careful and believe that these methods have a large future, primarily patient’s good should however be kept in mind.

  7. Calibration of ionization chamber survey meter

    International Nuclear Information System (INIS)

    Kadhim, A.K.; Kadni, T.B.

    2016-01-01

    Radiation measuring devices need to process calibration which lose their sensitivity and the extent of the response and the amount of stability under a changing conditions from time to time and this period depends on the nature and use of field in which used devices. A comparison study was done toa (45 I P) ( ionization chamber survey meter) and this showed the variation factor in five different years. This study also displayed the concept of radiation instrument calibration and necessity of every year calibration of them.In this project we used the five years calibration data for ionization chamber survey meter model Inspector (1/C F). the value deviation (∆ %) of Cfs for four years of calibration in comparison of C F for the year 2007 are very high and the device under research is not good to use in field and reliable because the ionization chamber is very sensitive to humidity and must calibrate a year or less, or due ing every two years and must maintain carefully to reduce the discarded effects the measurements.

  8. Ionization photophysics and spectroscopy of dicyanoacetylene

    International Nuclear Information System (INIS)

    Leach, Sydney; Champion, Norbert; Schwell, Martin; Bénilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire; Garcia, Gustavo A.; Gaie-Levrel, François; Guillemin, Jean-Claude

    2013-01-01

    Photoionization of dicyanoacetylene was studied using synchrotron radiation over the excitation range 8–25 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and detailed spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of dicyanoacetylene was measured as 11.80 ± 0.01 eV. A detailed analysis of the cation spectroscopy involves new aspects and new assignments of the vibrational components to excitation of the quasi-degenerate A 2 Π g , B 2 Σ g + states as well as the C 2 Σ u + and D 2 Π u states of the cation. Some of the structured autoionization features observed in the 12.4–15 eV region of the total ion yield spectrum were assigned to vibrational components of valence shell transitions and to two previously unknown Rydberg series converging to the D 2 Π u state of C 4 N 2 + . The appearance energies of the fragment ions C 4 N + , C 3 N + , C 4 + , C 2 N + , and C 2 + were measured and their heats of formation were determined and compared with existing literature values. Thermochemical calculations of the appearance potentials of these and other weaker ions were used to infer aspects of dissociative ionization pathways

  9. Stokes-attenuated tunneling ionization of molecules

    Science.gov (United States)

    Kornev, Aleksei S.; Zon, Boris A.

    2018-03-01

    We set forth the quantum theory of ionic vibrational-level population by means of tunneling ionization of a molecule. Specific calculations are carried out for the H2 molecule. The results are in qualitative agreement with the experimental data [X. Urbain et al., Phys. Rev. Lett. 92, 163004 (2004), 10.1103/PhysRevLett.92.163004]. Our account for the excited vibrational levels reveals an interplay of two tendencies which contribute to the ionization rate: (i) It decreases due to additional energy absorption needed to populate these states and (ii) it increases together with the Franck-Condon factors which are large for these states. We show that these two tendencies practically compensate each other. The average quantitative disagreement between the theory and experiment amounts to ˜30 %. The same disagreement takes place when using the frozen approximation for the description of the nuclei motion. We demonstrated that the light-dressing effect for H2 leads to the dependence of the ionization rate on the angle between the molecule axis and the polarization vector of the radiation.

  10. Ionizing radiation induces stemness in cancer cells.

    Directory of Open Access Journals (Sweden)

    Laura Ghisolfi

    Full Text Available The cancer stem cell (CSC model posits the presence of a small number of CSCs in the heterogeneous cancer cell population that are ultimately responsible for tumor initiation, as well as cancer recurrence and metastasis. CSCs have been isolated from a variety of human cancers and are able to generate a hierarchical and heterogeneous cancer cell population. CSCs are also resistant to conventional chemo- and radio-therapies. Here we report that ionizing radiation can induce stem cell-like properties in heterogeneous cancer cells. Exposure of non-stem cancer cells to ionizing radiation enhanced spherogenesis, and this was accompanied by upregulation of the pluripotency genes Sox2 and Oct3/4. Knockdown of Sox2 or Oct3/4 inhibited radiation-induced spherogenesis and increased cellular sensitivity to radiation. These data demonstrate that ionizing radiation can activate stemness pathways in heterogeneous cancer cells, resulting in the enrichment of a CSC subpopulation with higher resistance to radiotherapy.

  11. The multiphoton ionization of uranium hexafluoride

    International Nuclear Information System (INIS)

    Armstrong, D.P.

    1992-05-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF 6 have been conducted using focused light from the Nd:YAG laser fundamental (λ=1064 nm) and its harmonics (λ=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF x + fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U n+ ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U 2+ ) intensity is much greater than that of the singly-charged uranium ion (U + ). For the case of the tunable dye laser experiments, the U n+ (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U 2+ ion and the absence or very small intensities of UF x + fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule

  12. Kinematics of 3-body in Ionization Collision

    International Nuclear Information System (INIS)

    Della Picca, Renata

    2003-01-01

    In this thesis we study three body problems in the frame of the collision theory. First, we deal with the process of autoionization by ion impact where the line profile of the electron emitted is strongly affected by the post-collision interaction with the Coulomb field of the outgoing projectile.Here we analyze how these effects are modified when the projectile velocity is in the close vicinity of the resonant electron velocity.In this energy range, the analysis of the resonance contribution is hindered by the characteristic 'electron capture to the continuum' divergence in the direct term.Here we present a detailed theoretical study of the interplay between both contributions, based on a generalization of the Final-State Interaction model.Finally we propose a modified parameterization of the autoionization line shape in the vicinity of the ECC cusp.Secondly, we study the direct ionization of an atomic target by the impact of a charge projectile, through analysis of the quintuple differential cross section (QDCS) which gives the most complete information about a ionization collision.Its study, without any approximation on the mass ratios can unveil new, not previously observed, structures.In particular, in this work the ionization of Hydrogen molecules by the impact of positrons and muons was studied and a new structure that has not been identified until now was found. Its main characteristics and a possible explanation are presented

  13. Electron-impact ionization of atomic ions: Theoretical results

    Energy Technology Data Exchange (ETDEWEB)

    Loch, S D; Burgos, J M Munoz; Ballance, C P; Ludlow, J; Lee, T-G; Fogle, M; Pindzola, M S [Auburn University, Auburn, AL 36849 (United States); Griffin, D C [Rollins College, Winter Park, FL 32789 (United States); Yumak, A; Yavuz, I; Altun, Z, E-mail: loch@physics.auburn.ed [Marmara University, Istanbul (Turkey)

    2009-11-15

    A brief overview is given of theoretical results for electron-impact ionization of atoms and ions. A description is given of the main theoretical methods, along with the databases where the data are archived. It is shown that for light species, ground and metastable ionization cross sections are in reasonable agreement with experiment when non-perturbative data are used for the near neutrals and distorted wave data are used for ions greater than a few times ionized. Some discrepancies between theory and experiment still remain for systems with open d and open p subshells. The sensitivity of ionization rate coefficients to the near threshold part of the ionization cross section is shown. The role of excited states in effective ionization rate coefficients is demonstrated and recent excited state ionization cross section results for H, He, He{sup +}, B{sup 2+} and Ne are presented.

  14. Biological effects of low-level ionizing and non-ionizing radiation

    International Nuclear Information System (INIS)

    Upton, A.C.

    1986-01-01

    Early in this century it was recognized that large doses of ionizing radiation could injure almost any tissue in the body, but small doses were generally thought to be harmless. By the middle of the century however it came to be suspected that even the smallest doses of ionizing radiation to the gonads might increase the risk of hereditary disease in subsequently-conceived offspring. Since then the hypothesis that carcinogenic and teratogenic effects also have no threshold has been adopted for purposes of radiological protection. It is estimated nevertheless that the risks that may be associated with natural background levels of ionizing irradiation are too small to be detectable. Hence validation of such risk estimates will depend on further elucidation of the dose-effect relationships and mechanisms of the effects in question, through studies at higher dose levels. In contrast to the situation with ionizing radiation, exposure to natural background levels of ultraviolet radiation has been implicated definitively in the etiology of skin cancers in fair-skinned individuals. Persons with inherited effects in DNA repair capacity are particularly susceptible. Non-ionizing radiations of other types can also affect health at high dose levels, but whether they can cause injury at low levels of exposure is not known

  15. Iron oxide nanomatrix facilitating metal ionization in matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Obena, Rofeamor P; Lin, Po-Chiao; Lu, Ying-Wei; Li, I-Che; del Mundo, Florian; Arco, Susan dR; Nuesca, Guillermo M; Lin, Chung-Chen; Chen, Yu-Ju

    2011-12-15

    The significance and epidemiological effects of metals to life necessitate the development of direct, efficient, and rapid method of analysis. Taking advantage of its simple, fast, and high-throughput features, we present a novel approach to metal ion detection by matrix-functionalized magnetic nanoparticle (matrix@MNP)-assisted MALDI-MS. Utilizing 21 biologically and environmentally relevant metal ion solutions, the performance of core and matrix@MNP against conventional matrixes in MALDI-MS and laser desorption ionization (LDI) MS were systemically tested to evaluate the versatility of matrix@MNP as ionization element. The matrix@MNPs provided 20- to >100-fold enhancement on detection sensitivity of metal ions and unambiguous identification through characteristic isotope patterns and accurate mass (<5 ppm), which may be attributed to its multifunctional role as metal chelator, preconcentrator, absorber, and reservoir of energy. Together with the comparison on the ionization behaviors of various metals having different ionization potentials (IP), we formulated a metal ionization mechanism model, alluding to the role of exciton pooling in matrix@MNP-assisted MALDI-MS. Moreover, the detection of Cu in spiked tap water demonstrated the practicability of this new approach as an efficient and direct alternative tool for fast, sensitive, and accurate determination of trace metal ions in real samples.

  16. Ionization chamber for high dose measurements

    International Nuclear Information System (INIS)

    Rodrigues Junior, Ary de Araujo

    2005-01-01

    Industrial gamma irradiators facilities are designed for processing large amounts of products, which are exposed to large doses of gamma radiation. The irradiation, in industrial scale, is usually carried out in a dynamic form, where the products go through a 60 Co gamma source with activity of TBq to P Bq (k Ci to MCi). The dose is estimated as being directly proportional to the time that the products spend to go through the source. However, in some situations, mainly for research purposes or for validation of customer process following the ISO 11137 requirements, it is required to irradiate small samples in a static position with fractional deliver doses. The samples are put inside the irradiation room at a fixed distance from the source and the dose is usually determined using dosimeters. The dose is only known after the irradiation, by reading the dosimeter. Nevertheless, in the industrial irradiators, usually different kinds of products with different densities go through between the source and the static position samples. So, the dose rate varies in function of the product density. A suitable methodology would be to monitor the samples dose in real time, measuring the dose on line with a radiation detector, which would improve the dose accuracy and avoid the overdose. A cylindrical ionization chamber of 0.9 cm 3 has been developed for high-doses real-time monitoring, during the sample irradiation at a static position in a 60 Co gamma industrial plant. Nitrogen and argon gas at pressure of 10 exp 5 Pa (1 bar) was utilized to fill the ionization chamber, for which an appropriate configuration was determined to be used as a detector for high-dose measurements. To transmit the signal generated in the ionization chamber to the associated electronic and processing unit, a 20 m mineral insulated cable was welded to the ionization chamber. The signal to noise ratio produced by the detector was about 100. The dosimeter system was tested at a category I gamma

  17. Five-photon ionization of atomic hydrogen at wavelengths around the threshold for four-photon ionization

    International Nuclear Information System (INIS)

    Gontier, Y.; Trahin, M.; Wolff-Rottke, B.; Rottke, H.; Welge, K.H.; Feldmann, D.

    1992-01-01

    Theoretical and experimental studies show the strong influence of the three-photon nearly resonant 2p state on four- and five-photon ionization of atomic hydrogen near the threshold for four-photon ionization. Changes in five-photon ionization occur when the four-photon ionization channel opens. The angular distributions of photoelectrons from five-photon ionization of H are studied at five wavelengths which cover the range from four-photon resonance with high-lying Rydberg states (n≥10) to direct four-photon ionization into the continuum. The role of resonances in this ionization process is discussed. A fair agreement is found in comparing experimental and theoretical results

  18. Electrostatic perturbations in partially ionized plasma with the effects of ionization and recombination

    International Nuclear Information System (INIS)

    Vranjes, J.; Tanaka, M.Y.; Kono, M.; Poedts, S.

    2004-01-01

    The behavior of the electrostatic ion acoustic mode in a partially ionized plasma is studied in the presence of collisions which involve processes of ionization and recombination, taking into account the dynamics of the neutrals caused by elastic and inelastic collisions with ions. The application of the model to space plasmas, which are usually subject to gravity, is discussed in detail. A dispersion equation which includes the effects of ionization and recombination is derived and the stability/instability conditions are discussed. Parameters applicable to a region of the upper solar chromosphere are used and the increment of the ion sound wave is calculated yielding an unstable ion sound wave for wavelengths larger than 20 km

  19. Determination of the first ionization potential of actinides by resonance ionization mass spectroscopy

    International Nuclear Information System (INIS)

    Koehler, S.; Albus, F.; Dibenberger, R.; Erdmann, N.; Funk, H.; Hasse, H.; Herrmann, G.; Huber, G.; Kluge, H.; Nunnemann, M.; Passler, G.; Rao, P.M.; Riegel, J.; Trautmann, N.; Urban, F.

    1995-01-01

    Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential of transuranium elements. The first ionization potentials (IP) of americium and curium have been measured for the first time to IP Am =5.9738(2) and IP Cm =5.9913(8) eV, respectively, using only 10 12 atoms of 243 Am and 248 Cm. The same technique was applied to thorium, neptunium, and plutonium yielding IP T H =6.3067(2), IP N P =6.2655(2), and IP Pu =6.0257(8) eV. The good agreement of our results with the literature data proves the precision of the method which was additionally confirmed by the analysis of Rydberg seris of americium measured by RIMS. copyright American Institute of Physics 1995

  20. Data on ionization, excitation, dissociation and dissociative ionization of targets by helium ion bombardments, (1)

    International Nuclear Information System (INIS)

    Oda, Nobuo; Urakawa, Junji

    1984-03-01

    This report presents a compilation of the experimental data on cross sections for the ionization, excitation, dissociation and dissociative ionization processes of targets in helium ion impacts on atoms and molecules under a single collision condition. These measurements were carried out in the energy range from several keV to 3.5 MeV. A systematic survey has been made on the literatures from 1975 to the end of 1982. A list of references is also given, including relevant papers published before 1975. (author)

  1. Saha and temperature relaxation approximations for the study of ionization instability in partially ionized plasma

    International Nuclear Information System (INIS)

    Numano, M.

    1976-01-01

    The growth rates for the ionization instability obtained using the Saha and temperature relaxation approximations are compared with those obtained from an exact treatment, and the requirements for validity of these two approximations are obtained analytically. For the range of plasma parameters pertinent to MHD power generation it is found that the Saha approximation is valid for relatively high electron temperature, which it becomes inapplicable as the electron temperature is decreased. On the other hand, the temperature relaxation approximation is accurate over a wide range of electron temperature. It is found also that the marginal condition for the ionization instability is correctly obtained from both approximations. (author)

  2. Comparison between radiological protection against ionizing radiation and non ionizing radiation

    International Nuclear Information System (INIS)

    Jammet, H.P.

    1992-01-01

    Protection against IR and NIR developed in completely different ways because of the very different evolution of the techniques they involve. While as soon as 1928, the International Society of Radiology created the International Commission of Radiological Protection, we had to wait until 1977 to see the creation of the International Committee for NIR (INIRC) by IRPA. To compare protection against Ionizing Radiations and Non Ionizing Radiations we will first carry out a general analysis of its components and then we will draw the general conclusions leading to a quite comparable evolution. (author)

  3. Comparison between radiological protection against ionizing radiation and non-ionizing radiation

    International Nuclear Information System (INIS)

    Jammet, H.P.

    1988-01-01

    The comparison of doctrines concerning protection against ionizing and non-ionizing radiation is a difficult task, because of the many areas in which it is applied. Radiological pollution has grown during the century, but its evolution has not been concomitant. This has resulted in a distortion that can be identified in the successive steps of the evaluation and protection against such radiation. For a better understanding, this discussion deals with the differences in interaction with matter and the induction of the related risks, on the varieties of protection systems and monitoring procedures

  4. Re-ionization of a partially ionized plasma by an Alfven wave of moderate amplitude

    International Nuclear Information System (INIS)

    Brennan, M.H.; Sawley, M.L.

    1980-01-01

    The use of forced magnetic-acoustic oscillations to investigate the effect of a torsional hydromagnetic (Alfven) wave pulse of moderate amplitude on the properties of a partially ionized afterglow helium plasma is reported. Observations of the magnetic flux associated with the oscillations, measured at a number of frequencies are used to determine radial density profiles and to provide estimates of plasma temperature. The torsional wave is shown to cause significant re-ionization of the plasma with no corresponding increase in the plasma temperature. The presence of a number of energetic particles is evidenced by the production of a significant number of doubly charged helium ions. (author)

  5. MAGNETIC RECONNECTION IN NON-EQUILIBRIUM IONIZATION PLASMA

    International Nuclear Information System (INIS)

    Imada, S.; Shimizu, T.; Murakami, I.; Watanabe, T.; Hara, H.

    2011-01-01

    We have studied the effect of time-dependent ionization and the recombination processes on magnetic reconnection in the solar corona. Petschek-type steady reconnection, in which the magnetic energy is mainly converted at the slow-mode shocks, was assumed. We carried out the time-dependent ionization calculation in the magnetic reconnection structure. We only calculated the transient ionization of iron; the other species were assumed to be in ionization equilibrium. The intensity of line emissions at specific wavelengths was also calculated for comparison with Hinode or other observations in future. We found the following: (1) iron is mostly in non-equilibrium ionization in the reconnection region; (2) the intensity of line emission estimated by the time-dependent ionization calculation is significantly different from that determined from the ionization equilibrium assumption; (3) the effect of time-dependent ionization is sensitive to the electron density in the case where the electron density is less than 10 10 cm –3 ; (4) the effect of thermal conduction lessens the time-dependent ionization effect; and (5) the effect of radiative cooling is negligibly small even if we take into account time-dependent ionization.

  6. MEASURING THE SOURCES OF THE INTERGALACTIC IONIZING FLUX

    International Nuclear Information System (INIS)

    Cowie, L. L.; Barger, A. J.; Trouille, L.

    2009-01-01

    We use a wide-field (0.9 deg 2 ) X-ray sample with optical and Galaxy Evolution Explorer (GALEX) ultraviolet observations to measure the contribution of active galactic nuclei (AGNs) to the ionizing flux as a function of redshift. Our analysis shows that the AGN contribution to the metagalactic ionizing background peaks at around z = 2. The measured values of the ionizing background from the AGNs are lower than previous estimates and confirm that ionization from AGNs is insufficient to maintain the observed ionization of the intergalactic medium (IGM) at z > 3. We show that only X-ray sources with broad lines in their optical spectra have detectable ionizing flux and that the ionizing flux seen in an AGN is not correlated with its X-ray color. We also use the GALEX observations of the GOODS-N region to place a 2σ upper limit of 0.008 on the average ionization fraction f ν (700 A)/f ν (1500 A) for 626 UV selected galaxies in the redshift range z = 0.9-1.4. We then use this limit to estimate an upper bound to the galaxy contribution in the redshift range z = 0-5. If the z ∼ 1.15 ionization fraction is appropriate for higher-redshift galaxies, then contributions from the galaxy population are also too low to account for the IGM ionization at the highest redshifts (z > 4).

  7. Ionization photophysics and spectroscopy of dicyanoacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Leach, Sydney, E-mail: Sydney.Leach@obspm.fr, E-mail: Martin.Schwell@lisa.u-pec.fr; Champion, Norbert [LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon (France); Schwell, Martin, E-mail: Sydney.Leach@obspm.fr, E-mail: Martin.Schwell@lisa.u-pec.fr; Bénilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire [LISA UMR CNRS 7583, Université Paris-Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil (France); Garcia, Gustavo A.; Gaie-Levrel, François [Synchrotron SOLEIL, L’Orme des Merisiers, St. Aubin, B.P. 48, 91192 Gif-sur-Yvette Cedex (France); Guillemin, Jean-Claude [Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7 (France)

    2013-11-14

    Photoionization of dicyanoacetylene was studied using synchrotron radiation over the excitation range 8–25 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and detailed spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of dicyanoacetylene was measured as 11.80 ± 0.01 eV. A detailed analysis of the cation spectroscopy involves new aspects and new assignments of the vibrational components to excitation of the quasi-degenerate A{sup 2}Π{sub g}, B{sup 2}Σ{sub g}{sup +} states as well as the C{sup 2}Σ{sub u}{sup +} and D{sup 2}Π{sub u} states of the cation. Some of the structured autoionization features observed in the 12.4–15 eV region of the total ion yield spectrum were assigned to vibrational components of valence shell transitions and to two previously unknown Rydberg series converging to the D{sup 2}Π{sub u} state of C{sub 4}N{sub 2}{sup +}. The appearance energies of the fragment ions C{sub 4}N{sup +}, C{sub 3}N{sup +}, C{sub 4}{sup +}, C{sub 2}N{sup +}, and C{sub 2}{sup +} were measured and their heats of formation were determined and compared with existing literature values. Thermochemical calculations of the appearance potentials of these and other weaker ions were used to infer aspects of dissociative ionization pathways.

  8. Coating compositions hardenable by ionization beams

    International Nuclear Information System (INIS)

    Chaudhari, D.; Haering, E.; Dobbelstein, A.; Hoselmann, W.

    1976-01-01

    Coating compositions hardenable by ionizing radiation are described which contain as binding agents a mixture of at least 1 unsaturated olefin compound containing urethane groups, and at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound containing the urethane groups is a reaction product of a compound containing carboxylic acid groups and a compound containing at least 1 isocyanate group where the mixture of the two olefins may contain conventional additives of the lacquer industry. 6 claims, no drawings

  9. Single Photon Double Ionization of Atomic Oxygen

    Science.gov (United States)

    Wickramarathna, Madhushani; Gorczyca, Thomas; Ballance, Connor; Stolte, Wayne

    2017-04-01

    Single photon double ionization cross sections are calculated using an R-matrix with pseudostates (RMPS) method which was recently applied by Gorczyca et al. for the double photoionization of helium. With the convergence of these theoretical calculations for the simple case of helium, we extend this methodology to consider the more complex case of oxygen double photoionization. We compare our calculated results with recent measurements at the Advanced Light Source, as well as earlier experimental measurements. Our RMPS results agree well, qualitatively, with the experimental measurements, but there exist outstanding discrepancies to be addressed. This project is supported by NASA APRA award NNX17AD41G.

  10. Tooth-germ damage by ionizing radiation

    International Nuclear Information System (INIS)

    Sobkowiak, E.M.; Beetke, E.; Bienengraeber, V.; Held, M.; Kittner, K.H.

    1977-01-01

    Experiments on animals (four-week-old dogs) were conducted in an investigation made to study the possibility of dose-dependent tooth-germ damage produced by ionizing radiation. The individual doses were 50 R and 200 R, respectively, and they were administered once to three times at weekly intervals. Hyperemia and edemata could be observed on tooth-germ pulps from 150 R onward. Both of these conditions became more acute as the radiation dose increased (from 150 R to 600 R). Possible damage to both the dentin and enamel is pointed out. (author)

  11. Numerical double layer solutions with ionization

    International Nuclear Information System (INIS)

    Andersson, D.; Soerensen, J.

    1982-08-01

    Maxwell's equation div D = ro in one dimension is solved numerically, taking ionization into account. Time independent anode sheath and double layer solutions are obtained. By varying voltage, neutral gas pressure, temperature of the trapped ions on the cathode side and density and temperature of the trapped electrones on the anode side, diagrams are constructed that show permissible combinations of these parameters. Results from a recent experiment form a subset. Distribution functions, the Langmuir condition, some scaling laws and a possible application to the lower ionosphere are discussed. (Authors)

  12. Role of Ionizing Radiation in Neurodegenerative Diseases

    Directory of Open Access Journals (Sweden)

    Neel K. Sharma

    2018-05-01

    Full Text Available Ionizing radiation (IR from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR.

  13. Individual dosemeter with ionization chamber for intervention

    International Nuclear Information System (INIS)

    Prigent, M.

    1982-01-01

    The altogether intervention ratemeter-dosemeter is a device for work condition control and for dosimetry of intervention gang in hostile medium. A portable irradiation marker with ionization chamber either carried by staff, either put at the work post, delivers an information function of the surrounding irradiation field in which moves the intervention staff. The information is processed so as the absorbed dose rate and the absorbed dose are given simultaneously. The connection between the marker and the process device is made by a cable (up to 100m) or by radio link [fr

  14. Indigenously built resonance ionization mass spectrometer

    International Nuclear Information System (INIS)

    Razvi, M.A.N.; Jayasekharan, T.; Thankarajan, K.; Guhagarkar, M.B.; Dixit, M.N.; Bhale, G.L.

    2000-04-01

    Design, fabrication and performance testing of an indigenously built Resonance Ionization Mass Spectrometer (RIMS) is presented in this report. The instrument is totally indigenous, but for the laser components consisting of the excimer laser and tunable dye lasers. Constructional details of atomic beam source and linear time-of-flight mass spectrometer are included. Finally, commissioning and performance testing of the instrument is described. Mass resolving power of 400 and a detection limit of 100 atoms has been achieved using this RIMS set-up. (author)

  15. Genetic and chromosomal effects of ionizing radiation

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The genetic and chromosomal effects of ionizing radiations deal with those effects in the descendants of the individuals irradiated. The information base concerning genetic and chromosomal injury to humans from radiation is less adequate than is the information base for cancer and leukemia. As a result, it is not possible to make the kinds of quantitative estimates that have been made for carcinogenesis in previous chapters of this book. The chapter includes a detailed explanation of various types of genetic injuries such as chromosomal diseases, x-linked diseases, autosomal dominant diseases, recessive diseases, and irregularly inherited diseases. Quantitative estimates of mutation rates and incidences are given based on atomic bomb survivors data

  16. Cylindrical ionization chamber with compressed krypton

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Viyar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Puimedon, J.; Saens, K.; Salinas, A.; Sarsa, M.

    1993-01-01

    A cylindrical ionization chamber with a grid is used to search for double positron decay and atomic electron conversion to a positron in 78 Kr. Krypton is the working gas material of the chamber. The spectrometric characteristics of the chamber filled with krypton and xenon are presented. The energy resolution is 2.1% for an energy of 1.84 MeV (the source of γ-quanta is 88 Y) when the chamber is filled with a mixture of Kr+0.2% H 2 under a pressure of 25 atm

  17. Medical uses non-ionizing radiation

    International Nuclear Information System (INIS)

    Ubeda Maeso, A.; Trillo Ruiz, M. A.

    2016-01-01

    This article reviews various clinical applications of non-ionizing radiation, focusing on the Hz-GHz frequency range. Depending on the signal characteristics, the applications cover several therapeutic areas, including osteology and traumatology, tissue regeneration, physiotherapy, chronic pain treatment, neurology, cardiology, urology and oncology. Electromagnetic therapies have proved simple, safe, low cost, devoid of side effects and able to treat the underlying pathology rather than simply alleviate the symptoms. Therefore, it is predictable that these therapies will have as serious impact on public health and associated costs. (Author)

  18. Impact-ionization autosolitons in compensated silicon

    International Nuclear Information System (INIS)

    Musaev, A.M.

    2004-01-01

    The results of the experimental identification and study on the autosolitons with the charge carriers self-production by the impact ionization of the indium deep acceptor levels in silicon in the strong electric fields at the temperature of 77 K are presented. The role of the activator in the considered autosolitons excitation model is played by the free charge carriers concentration and the role of the inhibitor by the carriers temperature. The solitons existence is determined by the fact, that the area of the carriers high concentration in the autosolitons center does not spread, while the diffusion flow from the autosolitons center is counterbalanced by the thermodiffusion flow [ru

  19. Pencil-shaped radiation detection ionization chamber

    International Nuclear Information System (INIS)

    Suzuki, A.

    1979-01-01

    A radiation detection ionization chamber is described. It consists of an elongated cylindrical pencil-shaped tubing forming an outer wall of the chamber and a center electrode disposed along the major axis of the tubing. The length of the chamber is substantially greater than the diameter. A cable connecting portion at one end of the chamber is provided for connecting the chamber to a triaxial cable. An end support portion is connected at the other end of the chamber for supporting and tensioning the center electrode. 17 claims

  20. Enhanced ionized impurity scattering in nanowires

    Science.gov (United States)

    Oh, Jung Hyun; Lee, Seok-Hee; Shin, Mincheol

    2013-06-01

    The electronic resistivity in silicon nanowires is investigated by taking into account scattering as well as the donor deactivation from the dielectric mismatch. The effects of poorly screened dopant atoms from the dielectric mismatch and variable carrier density in nanowires are found to play a crucial role in determining the nanowire resistivity. Using Green's function method within the self-consistent Born approximation, it is shown that donor deactivation and ionized impurity scattering combined with the charged interface traps successfully to explain the increase in the resistivity of Si nanowires while reducing the radius, measured by Björk et al. [Nature Nanotech. 4, 103 (2009)].

  1. Ionizing radiations simulation on bipolar components

    International Nuclear Information System (INIS)

    Montagner, X.

    1999-01-01

    This thesis presents the ionizing radiation effects on bipolar components and more specially their behavior facing the total dose. The first part is devoted to the radiation environments with a special attention to the spatial environments and new emergent environments. The specificities of bipolar components are then presented and their behavior facing the interactions. The physical mechanisms bound to the dose rate are also discussed. The second part presents a physical analysis of degradations induced by the cumulated dosimetry on bipolar components and simulation with the ATLAS code. The third part exposes an electric empirical simulation induced by the cumulated dose in static conditions. (A.L.B.)

  2. Monitoring occupational exposure to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Button, J.B.C. [Radiation Safety Consultancy, Engadine, NSW (Australia)

    1997-12-31

    A brief overview is presented of methods of monitoring occupational exposure to ionizing radiation together with reasons for such monitoring and maintaining dose histories of radiation occupationally exposed persons. The various Australian providers of external radiation monitoring services and the types of dosemeters they supply are briefly described together with some monitoring results. Biological monitoring methods, are used to determine internal radiation dose. Whole body monitors, used for this purpose are available at Australian Radiation Lab., ANSTO and a few hospitals. Brief mention is made of the Australian National Radiation Dose Register and its objectives. 8 refs., 9 tabs.

  3. Monitoring occupational exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Button, J.B.C.

    1997-01-01

    A brief overview is presented of methods of monitoring occupational exposure to ionizing radiation together with reasons for such monitoring and maintaining dose histories of radiation occupationally exposed persons. The various Australian providers of external radiation monitoring services and the types of dosemeters they supply are briefly described together with some monitoring results. Biological monitoring methods, are used to determine internal radiation dose. Whole body monitors, used for this purpose are available at Australian Radiation Lab., ANSTO and a few hospitals. Brief mention is made of the Australian National Radiation Dose Register and its objectives

  4. Waveshifters and Scintillators for Ionizing Radiation Detection

    International Nuclear Information System (INIS)

    Baumgaugh, B.; Bishop, J.; Karmgard, D.; Marchant, J.; McKenna, M.; Ruchti, R.; Vigneault, M.; Hernandez, L.; Hurlbut, C.

    2007-01-01

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments

  5. Signal processing for liquid ionization calorimeters

    International Nuclear Information System (INIS)

    Cleland, W.E.; Stern, E.G.

    1992-01-01

    We present the results of a study of the effects of thermal and pileup noise in liquid ionization calorimeters operating in a high luminosity calorimeters operating in a high luminosity environment. The method of optimal filtering of multiply-sampled signals which may be used to improve the timing and amplitude resolution of calorimeter signals is described, and its implications for signal shaping functions are examined. The dependence of the time and amplitude resolution on the relative strength of the pileup and thermal noise, which varies with such parameters as luminosity, rapidity and calorimeter cell size, is examined

  6. Nonproliferation and safeguarding via ionization detection

    International Nuclear Information System (INIS)

    Koster, J.E.; Johnson, J.P.; Steadman, P.

    1995-01-01

    A significant signature of the presence of special nuclear material (SNM) is ionizing radiation. SNM naturally decays with the emission of alpha particles, gamma rays, and neutrons. Detecting and monitoring these emissions is an important capability for international safeguards. A new detection method collects the ions produced by such radiation in ambient air. Alpha particles in particular are specific to heavy nuclei but have very short range. The ions produced by an alpha, however, can be transported tens of meters to an ion detector. These new monitors are rugged, very sensitive, respond in real time, and in most cases are quite portable

  7. Applications of ionizing radiation for monuments conservation

    International Nuclear Information System (INIS)

    Chyzewski, M.; Galant, S.; Perkowski, J.

    1996-01-01

    Ionizing radiation can be used for conservation of monuments and old art objects. The irradiation of wooden and cellulose objects for disinfestation has been described. The irradiation conditions and lethal doses in respect to different species have been discussed. The different technique is the radiation consolidation of historical objects made of various materials. The method consists in radiation polymerization. The object undergoing conservation is saturated with monomer prior irradiation. The radiation polymerization results in consolidation of the object pieces and reinforcement of its material. 3 figs

  8. Detection of food treated with ionizing radiation

    International Nuclear Information System (INIS)

    Delincee, H.

    1998-01-01

    Treatment of food with ionizing energy-'food irradiation'- is finally becoming reality in many countries. The benefits include an improvement in food hygiene, spoilage reduction and extension of shelf-life. Although properly irradiated food is safe and wholesome, consumers should be able to make their own free choice between irradiated and non-irradiated food. For this purpose labelling is indispensable. In order to check compliance with existing regulations, detection of radiation treatment by analysing the food itself is highly desirable. Significant progress has been made in recent years in developing analytical detection methods utilizing changes in food originating from the radiation treatment

  9. Role of Ionizing Radiation in Neurodegenerative Diseases

    Science.gov (United States)

    Sharma, Neel K.; Sharma, Rupali; Mathur, Deepali; Sharad, Shashwat; Minhas, Gillipsie; Bhatia, Kulsajan; Anand, Akshay; Ghosh, Sanchita P.

    2018-01-01

    Ionizing radiation (IR) from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR. PMID:29867445

  10. The Ionizing Radiation Environment on the Moon

    Science.gov (United States)

    Adams, J. H., Jr.; Bhattacharya, M.; Lin, Zi-Wei; Pendleton, G.

    2006-01-01

    The ionizing radiation environment on the moon that contributes to the radiation hazard for astronauts consists of galactic cosmic rays, solar energetic particles and albedo particles from the lunar surface. We will present calculations of the absorbed dose and the dose equivalent to various organs in this environment during quiet times and during large solar particle events. We will evaluate the contribution of solar particles other than protons and the contributions of the various forms of albedo. We will use the results to determine which particle fluxes must be known in order to estimate the radiation hazard.

  11. Resonance ionization detection of combustion radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  12. The physics of the ionized media

    International Nuclear Information System (INIS)

    Gresillon, D.; Virmont, J.

    1988-01-01

    The 1988 progress report of the laboratory of the Ionized Media Physics (Polytechnic School, France), is presented. The most important results are obtained on the field of waves: the study of the conversion of a proper mode into another one, by means of the electromagnetic wave scattering. The research program involves the following topics: plasma nonlinear physics, fluctuations and transport phenomena in magnetic fusion plasmas, plasmas and negatif ion beams, beam and plasma radiations, atomic physics and spectroscopic plasma diagnostics, The published papers, the congress communications, the thesis and the patents are listed [fr

  13. Exposure to low doses of ionizing radiations

    International Nuclear Information System (INIS)

    Le Guen, B.

    2008-01-01

    The author discusses the knowledge about the effects of ionizing radiations on mankind. Some of them have been well documented (skin cancer and leukaemia for the pioneer scientists who worked on radiations, some other types of cancer for workers who handled luminescent paints, rock miners, nuclear explosion survivors, patients submitted to radiological treatments). He also evokes the issue of hereditary cancers, and discusses the issue of low dose irradiation where some surveys can now be performed on workers. He discusses the biological effects of these low doses. He outlines that many questions remain about these effects, notably the influence of dose level and of dose rate level on the biological reaction

  14. Shall we be afraid by ionizing radiations?

    International Nuclear Information System (INIS)

    Gerard, P.

    1996-01-01

    A conference about ionizing radiations and the frighten they provoke was organised on the 30 May 1996 at Lyon in France. A responsible of the radiotherapy-oncology service, of the hospital center of Lyon, answered. The low doses are without effects on organs, for pregnant women if the dose is higher than 200 milli sieverts, abortion is advised; in fact the principle frighten is the carcinogens risk; the norms recommended by ICRP are to maintain the radiations doses in the a level as low as reasonably achievable. (ALARA principle)

  15. Resonance ionization spectroscopy: Counting noble gas atoms

    International Nuclear Information System (INIS)

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-01-01

    The purpose of this paper is to describe new work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions). When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. We show that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective. (orig./FKS)

  16. Pregnancy and exposure to ionizing radiations

    International Nuclear Information System (INIS)

    Topsoba, T.L.; Tapsoba, T.L.; Cisse, R.; Lougue Sorgho, L.C.; Bamouni, Y.A.; Gassama Seck, S.

    2006-01-01

    The sensitivity of the embryo and foetus varies during pregnancy. Recent studies confirm that the principal damage is mental retardation. It is generally admitted that the risk is negligible for a dose 200 mSv.The objective of this work is to provide precise information on the various risks related to the irradiation for the foetus, according to the age of gestation and delivered dose, and the action to be taken in case of accidental irradiation. The medical use of ionizing radiation in pregnant women can only be considered within the framework of precise information. (author)

  17. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  18. Health Effects of Non-Ionizing Radiation on Human

    International Nuclear Information System (INIS)

    Zubaidah-Alatas; Yanti Lusiyanti

    2001-01-01

    Increases of development and use of equipment that procedures non-ionizing radiant energy such as laser, radar, microwave ovens, power lines and hand phones, bring about public concern about the possible health effects owing to the non-ionizing radiation exposure. Non ionizing electromagnetic radiation compared to ionizing radiation, has longer wavelength, lower frequency, and lower photon energy in its interaction with body tissues. The term on non-ionizing radiation refers to the groups of electromagnetic radiations with energies less than about 10 eV corresponding to wavelengths in the ultraviolet, visible, infra red microwave and radiofrequency spectral regions. This paper describes the current state of knowledge about types of non-ionizing radiation and the health effects at molecular and cellular levels as well as its effects on human health. (author)

  19. Possible ionization ''ignition'' in laser-driven clusters

    International Nuclear Information System (INIS)

    Rose-Petruck, C.; Schafer, K.J.; Barty, C.P.J.

    1995-01-01

    The authors use Classical Trajectory Monte Carlo (CTMC) simulations to study the ionization of small rare gas clusters in short pulse, high intensity laser fields. They calculate, for a cluster of 25 neon atoms, the ionization stage reached and the average kinetic energy of the ionized electrons as functions of time and peak laser intensity. The CTMC calculations mimic the results of the much simpler barrier suppression model in the limit of isolated atoms. At solid density the results give much more ionization in the cluster than that predicted by the barrier suppression model. They find that when the laser intensity reaches a threshold value such that on average one electron is ionized from each atom, the cluster atoms rapidly move to higher ionization stages, approaching Ne +8 in a few femtoseconds. This ignition process creates an ultrafast pulse of energetic electrons in the cluster at quite modest laser intensities

  20. Electron-impact single and double ionization of W

    International Nuclear Information System (INIS)

    Pindzola, M S; Loch, S D; Foster, A R

    2017-01-01

    Electron-impact single and double ionization cross sections for the W atom are calculated using a semi-relativistic distorted-wave method. The cross sections include contributions from single direct ionization, double direct ionization and excitation-autoionization. Branching ratio calculations are made to determine whether an excitation may contribute to single or double ionization. We check the accuracy of the semi-relativistic distorted-wave calculations for direct ionization of various subshells by comparison with fully-relativistic distorted-wave calculations. We also check the accuracy of the perturbative distorted-wave calculations for direct ionization of the outer most subshells by comparison with non-perturbative time-dependent close-coupling calculations. (paper)

  1. Study of ionization process of matrix molecules in matrix-assisted laser desorption ionization

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Kazumasa; Sato, Asami; Hashimoto, Kenro; Fujino, Tatsuya, E-mail: fujino@tmu.ac.jp

    2013-06-20

    Highlights: ► Proton transfer and adduction reaction of matrix in MALDI were studied. ► Hydroxyl group forming intramolecular hydrogen bond was related to the ionization. ► Intramolecular proton transfer in the electronic excited state was the initial step. ► Non-volatile analytes stabilized protonated matrix in the ground state. ► A possible mechanism, “analyte support mechanism”, has been proposed. - Abstract: Proton transfer and adduction reaction of matrix molecules in matrix-assisted laser desorption ionization were studied. By using 2,4,6-trihydroxyacetophenone (THAP), 2,5-dihydroxybenzoic acid (DHBA), and their related compounds in which the position of a hydroxyl group is different, it was clarified that a hydroxyl group forming an intramolecular hydrogen bond is related to the ionization of matrix molecules. Intramolecular proton transfer in the electronic excited state of the matrix and subsequent proton adduction from a surrounding solvent to the charge-separated matrix are the initial steps for the ionization of matrix molecules. Nanosecond pump–probe NIR–UV mass spectrometry confirmed that the existence of analyte molecules having large dipole moment in their structures is necessary for the stabilization of [matrix + H]{sup +} in the electronic ground state.

  2. Ionized calcium measurements are influenced by albumin - should ionized calcium be corrected?

    DEFF Research Database (Denmark)

    Larsen, Trine R; Galthen-Sørensen, Mathias; Antonsen, Steen

    2014-01-01

    Abstract Measurement of ionized calcium (CaI) has been reported to be dependent on albumin concentration. We examined the correlation between albumin and CaI measured on different ion selective electrode analyzers and in different groups of patients in a large dataset, extracted from the laboratory...

  3. Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

    Directory of Open Access Journals (Sweden)

    Yunguang Huang

    2015-01-01

    Full Text Available A vacuum ultraviolet lamp based single photon ionization- (SPI- photoelectron ionization (PEI portable reflecting time-of-flight mass spectrometer (TOFMS was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX, SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1 with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear.

  4. State of the Art of Hard and Soft Ionization Mass Spectrometry

    International Nuclear Information System (INIS)

    Helal, A.I.

    2008-01-01

    The principles of hard and soft ionization sources, providing some details on the practical aspects of their uses as well as ionization mechanisms are discussed. The conditions and uses of hard ionization methods such as electron impact, thermal ionization and inductively coupled plasma techniques are discussed. Moreover, new generation of soft ionization methods such as matrix-assisted laser desorption/ionization, electro spray ionization and direct analysis in real time are illustrated

  5. Direct inner shell ionization accompanying heavy ion fusion reactions

    International Nuclear Information System (INIS)

    Sujkowski, Z.

    1987-07-01

    51 V+ 40 Ar (180 MeV) fusion reaction is studied by means of K X-ray-particle-γ-ray coincidences. K X-ray yields associated with various evaporation residues are determined separately for two ionization processes: the direct ionization by the projectile prior to the nuclear interaction and the postcollisional ionization due to the internal conversion of γ-rays. Implications for possible measurements of nuclear reaction times are discussed. 24 refs., 9 figs., 2 tabs. (author)

  6. Hand and shoe monitor using air ionization probes

    International Nuclear Information System (INIS)

    Fergus, R.W.

    1981-01-01

    A hand and shoe radiation monitor is provided which includes a probe support body defining a plurality of cells, within each cell there being an ionization probe. The support body provides structural strength for protecting the ionization probes from force applied to the support body during a radiation monitoring event. There is also provided a fast response time amplifier circuit for the output from the ionization probes

  7. Rydberg atoms ionization by microwave field and electromagnetic pulses

    International Nuclear Information System (INIS)

    Kaulakys, B.; Vilutis, G.

    1995-01-01

    A simple theory of the Rydberg atoms ionization by electromagnetic pulses and microwave field is presented. The analysis is based on the scale transformation which reduces the number of parameters and reveals the functional dependencies of the processes. It is shown that the observed ionization of Rydberg atoms by subpicosecond electromagnetic pulses scale classically. The threshold electric field required to ionise a Rydberg state may be simply evaluated in the photonic basis approach for the quantum dynamics or from the multiphoton ionization theory

  8. Electrical pulse burnout of transistors in intense ionizing radiation

    International Nuclear Information System (INIS)

    Hartman, E.F.; Evans, D.C.

    1975-01-01

    Tests examining possible synergistic effects of electrical pulses and ionizing radiation on transistors were performed and energy/power thresholds for transistor burnout determined. The effect of ionizing radiation on burnout thresholds was found to be minimal, indicating that electrical pulse testing in the absence of radiation produces burnout-threshold results which are applicable to IEMP studies. The conditions of ionized transistor junctions and radiation induced current surges at semiconductor device terminals are inherent in IEMP studies of electrical circuits

  9. Microwave Ionization of an Atomic Electron Wave Packet

    International Nuclear Information System (INIS)

    Noel, Michael W.; Ko, Lung; Gallagher, T. F.

    2001-01-01

    A short microwave pulse is used to ionize a lithium Rydberg wave packet launched from the core at a well-defined phase of the field. We observe a strong dependence on the relative phase between the motion of the wave packet and the oscillations of the field. This phase dependent ionization is also studied as a function of the relative frequency. Our experimental observations are in good qualitative agreement with a one-dimensional classical model of wave packet ionization

  10. Relativistic theory of electron-impact ionization

    International Nuclear Information System (INIS)

    Rosenberg, Leonard

    2010-01-01

    A relativistic version of an earlier, non-relativistic, formulation of the theory of ionization of an atomic system by electron impact is presented. With a time-independent resolvent operator taken as the basis for the dynamics, a wave equation is derived for a system with open channels consisting of two positive-energy electrons in an external field generated by the residual ion. Virtual intermediate states can be accounted for by the effective Hamiltonian that appears in the wave equation and which in principle may be constructed perturbatively. The asymptotic form of the wavefunction, modified by the effects of the long-range Coulomb interactions of the two electrons in the external field, is derived. These electrons are constrained, by projection operators which appear naturally in the theory, to propagate in positive-energy states only. The long-range Coulomb effects take the form of phase factors similar to those that are found in the non-relativistic version of the theory. With the boundary conditions established, an integral identity for the ionization amplitude is derived, and used to set up a distorted-wave Born expansion for the transition amplitude involving Coulomb-modified propagating waves.

  11. Kinetics of a plasma streamer ionization front

    Science.gov (United States)

    Taccogna, Francesco; Pellegrini, Fabrizio

    2018-02-01

    A streamer is a non-linear and non-local gas breakdown mode. Its large-scale coherent structures, such as the ionization front, are the final results of a hierarchical cascade starting from the single particle dynamics. Therefore, this phenomenon covers, by definition, different space and time scales. In this study, we have reproduced the ionization front formation and development by means of a particle-based numerical methodology. The physical system investigated concerns of a high-voltage ns-pulsed surface dielectric barrier discharge. Different reduced electric field regimes ranging from 50 to 500 Td have been considered for two gases: pure atomic Ar and molecular N2. Results have shown the detailed structure of the negative streamer: the leading edge, the head, the interior and the tail. Its dynamical evolution and the front propagation velocity have been calculated for the different cases. Finally, the deviation of the electron energy distribution function from equilibrium behavior has been pointed out as a result of a fast and very localized phenomenon.

  12. Radiation, ionization, and detection in nuclear medicine

    International Nuclear Information System (INIS)

    Gupta, Tapan K.

    2013-01-01

    Up-to-date information on a wide range of topics relating to radiation, ionization, and detection in nuclear medicine. In-depth coverage of basic radiophysics relating to diagnosis and therapy. Extensive discussion of instrumentation and radiation detectors. Detailed information on mathematical modelling of radiation detectors. Although our understanding of cancer has improved, the disease continues to be a leading cause of death across the world. The good news is that the recent technological developments in radiotherapy, radionuclide diagnostics and therapy, digital imaging systems, and detection technology have raised hope that cancer will in the future be combatted more efficiently and effectively. For this goal to be achieved, however, safe use of radionuclides and detailed knowledge of radiation sources are essential. Radiation, Ionization, and Detection in Nuclear Medicine addresses these subjects and related issues very clearly and elaborately and will serve as the definitive source of detailed information in the field. Individual chapters cover fundamental aspects of nuclear radiation, including dose and energy, sources, and shielding; the detection and measurement of radiation exposure, with detailed information on mathematical modelling; medical imaging; the different types of radiation detector and their working principles; basic principles of and experimental techniques for deposition of scintillating materials; device fabrication; the optical and electrical behaviors of radiation detectors; and the instrumentation used in nuclear medicine and its application. The book will be an invaluable source of information for academia, industry, practitioners, and researchers.

  13. Laser ionization and dissociation of hydrogen

    International Nuclear Information System (INIS)

    Buck, J.D.

    1987-01-01

    Experiments undertaken to further characterize the spectroscopic and photophysical properties of some important excited singlet states of molecular hydrogen and its deuterium isotopes are described. Attention was centered on high vibrational levels of the B, C, and B' states within about 1000 cm -1 of the second dissociation limit. A double-resonance excitation scheme was needed to access levels with a large average bond distance from the ground state. Two-photon absorption of tunable uv-laser radiation-pumped ground-state hydrogen molecules into selected rovibronic levels of the metastable EF double-minimum electronic state. A second tunable near-IR probe laser was scanned to generate ions by resonant multiphoton ionization, where the resonant levels were provided by B, C, B', and other levels near the dissociation limit. New information was obtained regarding line shapes and intensities. Time-of-flight ion mass selection permitted observation of additional excitation channels with dissociation superimposed on the ionization process to produce protons

  14. Hydrodynamic optical-field-ionized plasma channels

    Science.gov (United States)

    Shalloo, R. J.; Arran, C.; Corner, L.; Holloway, J.; Jonnerby, J.; Walczak, R.; Milchberg, H. M.; Hooker, S. M.

    2018-05-01

    We present experiments and numerical simulations which demonstrate that fully ionized, low-density plasma channels could be formed by hydrodynamic expansion of plasma columns produced by optical field ionization. Simulations of the hydrodynamic expansion of plasma columns formed in hydrogen by an axicon lens show the generation of 200 mm long plasma channels with axial densities of order ne(0 ) =1 ×1017cm-3 and lowest-order modes of spot size WM≈40 μ m . These simulations show that the laser energy required to generate the channels is modest: of order 1 mJ per centimeter of channel. The simulations are confirmed by experiments with a spherical lens which show the formation of short plasma channels with 1.5 ×1017cm-3≲ne(0 ) ≲1 ×1018cm-3 and 61 μ m ≳WM≳33 μ m . Low-density plasma channels of this type would appear to be well suited as multi-GeV laser-plasma accelerator stages capable of long-term operation at high pulse repetition rates.

  15. Amplifier Design for Proportional Ionization Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Baker, W. H.

    1950-08-24

    This paper presents the requirements of a nuclear amplifier of short resolving time, designed to accept pulses of widely varying amplitudes. Data are given which show that a proportional ionization chamber loaded with a 1,000-ohm resistor develops pulses of 0.5 microsecond duration and several volts amplitude. Results indicate that seven basic requirements are imposed on the amplifier when counting soft beta and gamma radiation in the presence of alpha particles, without absorbers. It should, (1) have a fast recovery time, (2) have a relatively good low frequency response, (3) accept pulses of widely varying heights without developing spurious pulsed, (4) have a limiting output stage, (5) preserve the inherently short rise time of the chamber, (6) minimize pulse integration, and (7) have sufficient gain to detect the weak pulses well below the chamber voltage at which continuous discharge takes place. The results obtained with an amplifier which meets these requirements is described. A formula is derived which indicates that redesign of the proportional ionization chamber might eliminate the need for an amplifier. This may be possible if the radioactive particles are collimated parallel to the collecting electrode.

  16. Degradation of chlorpyrifos by ionizing radiation

    International Nuclear Information System (INIS)

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

    2006-01-01

    Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60 Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GCFID). (author)

  17. Radiation, ionization, and detection in nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Tapan K. [Radiation Monitoring Devices Research, Nuclear Medicine, Watertown, MA (United States)

    2013-08-01

    Up-to-date information on a wide range of topics relating to radiation, ionization, and detection in nuclear medicine. In-depth coverage of basic radiophysics relating to diagnosis and therapy. Extensive discussion of instrumentation and radiation detectors. Detailed information on mathematical modelling of radiation detectors. Although our understanding of cancer has improved, the disease continues to be a leading cause of death across the world. The good news is that the recent technological developments in radiotherapy, radionuclide diagnostics and therapy, digital imaging systems, and detection technology have raised hope that cancer will in the future be combatted more efficiently and effectively. For this goal to be achieved, however, safe use of radionuclides and detailed knowledge of radiation sources are essential. Radiation, Ionization, and Detection in Nuclear Medicine addresses these subjects and related issues very clearly and elaborately and will serve as the definitive source of detailed information in the field. Individual chapters cover fundamental aspects of nuclear radiation, including dose and energy, sources, and shielding; the detection and measurement of radiation exposure, with detailed information on mathematical modelling; medical imaging; the different types of radiation detector and their working principles; basic principles of and experimental techniques for deposition of scintillating materials; device fabrication; the optical and electrical behaviors of radiation detectors; and the instrumentation used in nuclear medicine and its application. The book will be an invaluable source of information for academia, industry, practitioners, and researchers.

  18. Effects of ionizing radiations on proteins

    International Nuclear Information System (INIS)

    Maire, M. le; Foresta, B. de; Viel, A.; Thauvette, L.; Beauregard, G.; Potier, M.

    1990-01-01

    We have reinvestigated the use of ionizing radiations to measure the molecular mass of water-soluble or membrane proteins. Exposure of purified standard proteins to increasing doses of ionizing radiation causes progressive fragmentation of the native protein into defined peptide patterns. The coloured band corresponding to the intact protein was measured on the SDS gel as a function of dose to determine the dose (D 37.t ) corresponding to 37% of the initial amount of unfragmented protein deposited on the gel. This led to a calibration curve and the known molecular mass of the standard proteins. However, we have to conclude that this method is useless to determine the state of aggregation of a protein, since, for all the oligomers tested, the best fit was obtained by using the protomeric molecular mass, suggesting that there is no energy transfer between protomers. Furthermore, SDS greatly increases the fragmentation rate of proteins, which suggests additional calibration problems for membrane proteins in detergent or in the lipid bilayer. The main drawback of the technique is that some proteins behaved anomalously, leading to very large errors in the apparent target size as compared with true molecular mass. It is thus unreliable to apply the radiation method for absolute molecular-mass determination. We then focused on the novel finding that discrete fragmentation of proteins occurs at preferential sites, and this was studied with aspartate transcarbamylase. (author)

  19. Ionization photophysics and Rydberg spectroscopy of diacetylene

    KAUST Repository

    Schwell, Martin; Bé nilan, Yves; Fray, Nicolas; Gazeau, Marie Claire; Es-sebbar, Et-touhami; Gaie-Levrel, Franç ois; Champion, Norbert; Leach, Sydney Sydney

    2012-01-01

    Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.

  20. Ionization photophysics and Rydberg spectroscopy of diacetylene

    KAUST Repository

    Schwell, Martin

    2012-11-01

    Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B\\' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.

  1. Dust formation and ionization in novae

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuo; Sato, Shuji; Nariai, Kyoji.

    1979-01-01

    In order to explain the fact that some novae show the increase of infrared radiation indicating the formation of circumstellar dust grains while some others do not, the theory that the formation of dust in the circumstellar envelope of a nova depends on the intensity of ultraviolet radiation from a central star has been presented. It is known that the central star of a nova emits radiation at nearly constant rate, and its effective temperature rises. It was concluded that the novae with higher emission than a certain value are the poor candidates for dust formation because the whole envelope is ionized before dust is formed. But this conclusion is misleading. The evolution of the ultraviolet radiation emanating from a central star is summarized. The condensation of grains is possible when the partial pressure of the vapor, from which the grains are formed, becomes higher than the saturation vapor pressure. The temperature of grains can be estimated by equating the radiations absorbed and emitted. The grains evaporate if the grain temperature is higher than the condensation temperature. The formation of a Stroemgren sphere in the exploding envelope of a nova is discussed. For the formation of grains, it is necessary that temperature drops below the condensation temperature before the whole envelope is ionized. Hence dust grains do not grow if the grain temperature at a phase is higher than the condensation temperature. (Kako, I.)

  2. Calculational approach to ionization spectrometer design

    International Nuclear Information System (INIS)

    Gabriel, T.A.

    1974-01-01

    Many factors contribute to the design and overall performance of an ionization spectrometer. These factors include the conditions under which the spectrometer is to be used, the required performance, the development of the hadronic and electromagnetic cascades, leakage and binding energies, saturation effects of densely ionizing particles, nonuniform light collection, sampling fluctuations, etc. The calculational procedures developed at Oak Ridge National Laboratory that have been applied to many spectrometer designs and that include many of the influencing factors in spectrometer design are discussed. The incident-particle types which can be considered with some generality are protons, neutrons, pions, muons, electrons, positrons, and gamma rays. Charged kaons can also be considered but with less generality. The incident-particle energy range can extend into the hundreds of GeV range. The calculations have been verified by comparison with experimental data but only up to approximately 30 GeV. Some comparisons with experimental data are also discussed and presented so that the flexibility of the calculational methods can be demonstrated. (U.S.)

  3. Neurophysiological appropriateness of ionizing radiation effects

    International Nuclear Information System (INIS)

    Nyagu, A.I.; Loganovsky, K.N.

    1997-01-01

    The goal of this study was to compare bioelectrical activity of the brain in remote period of acute radiation sickness (ARS), chronic and prenatal irradiation as a result of the Chernobyl disaster. Registration of computerized 19-channel EEG, visual and somato-sensory evoked potentials have been carried out for 70 patients who had a verified ARS, 100 Chernobyl disaster survivors, who have been working in the Chernobyl exclusion zone since 1986-87 during 5 and more years, 50 prenatally irradiated children, and relevant controls. The relative risks of neurophysiological abnormalities are 4.5 for the ARS-patients, 3.6 for the chronically irradiated persons and 3.7 for the prenatally irradiated children. The data obtained testify to possibility of radiation-induced neurophysiological abnormalities in examined Chernobyl accident survivors which seems to be non-stochastic effects of ionizing radiation. For all examined irradiated patients it was typically an increasing of δ- and β- powers of EEG, particularly, in the frontal lobe shifted to the left fronto-temporal region, but spectral power of both θ- and α-range was significantly depressed. Aforesaid signs together with data of evoked potentials reflect the structural and functional abnormalities of limbic system and the left hemisphere as the first revealed neurophysiological appropriateness of ionizing radiation effects. (author)

  4. Neurophysiological appropriateness of ionizing radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Nyagu, A I; Loganovsky, K N [Department of Neurology, Inst. of Clinical Radiology, Scientific Centre for Radiation Medicine of Academy of Medical Sciences of Ukraine, Kiev (Ukraine)

    1997-11-01

    The goal of this study was to compare bioelectrical activity of the brain in remote period of acute radiation sickness (ARS), chronic and prenatal irradiation as a result of the Chernobyl disaster. Registration of computerized 19-channel EEG, visual and somato-sensory evoked potentials have been carried out for 70 patients who had a verified ARS, 100 Chernobyl disaster survivors, who have been working in the Chernobyl exclusion zone since 1986-87 during 5 and more years, 50 prenatally irradiated children, and relevant controls. The relative risks of neurophysiological abnormalities are 4.5 for the ARS-patients, 3.6 for the chronically irradiated persons and 3.7 for the prenatally irradiated children. The data obtained testify to possibility of radiation-induced neurophysiological abnormalities in examined Chernobyl accident survivors which seems to be non-stochastic effects of ionizing radiation. For all examined irradiated patients it was typically an increasing of {delta}- and {beta}- powers of EEG, particularly, in the frontal lobe shifted to the left fronto-temporal region, but spectral power of both {theta}- and {alpha}-range was significantly depressed. Aforesaid signs together with data of evoked potentials reflect the structural and functional abnormalities of limbic system and the left hemisphere as the first revealed neurophysiological appropriateness of ionizing radiation effects. (author). 25 refs.

  5. Initial ionization stage of FRC formation

    International Nuclear Information System (INIS)

    Commisso, R.J.; Armstrong, W.T.; Cochrane, J.C.; Ekdahl, C.A.; Lipson, J.; Linford, R.K.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.

    1980-01-01

    A Field-Reversed Configuration (FRC) is a prolate compact torus that is confined by poloidal fields only. Theta-pinch formation of an FRC employs an initial bias field, B 1 , whose direction is opposite to that of the main theta-pinch field. Some fraction of the flux associated with this bias field eventually constitutes the closed-field-line flux of the FRC. Experimental and theoretical evidence suggest that the longest-lived FRC's are obtained when the closed flux is maximized. Because the initial ionization is done in the presence of the bias field, the actual bias flux available at the time of application of the main theta-pinch field depends strongly on the initial ionization, or preionization, technique used. In this paper we report on experiments characterizing the previously used theta-pinch preionization technique that employed a net field (bias plus preionization) null, or zero-crossing, of the axial component of the magnetic field to break down the gas. We also discuss results of experiments designed to develop preionization techniques in which the gas breakdown is not accomplished by a zero-crossing

  6. Initial ionization stage of FRC formation

    Energy Technology Data Exchange (ETDEWEB)

    Commisso, R.J.; Armstrong, W.T.; Cochrane, J.C.; Ekdahl, C.A.; Lipson, J.; Linford, R.K.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.

    1980-01-01

    A Field-Reversed Configuration (FRC) is a prolate compact torus that is confined by poloidal fields only. Theta-pinch formation of an FRC employs an initial bias field, B/sub 1/, whose direction is opposite to that of the main theta-pinch field. Some fraction of the flux associated with this bias field eventually constitutes the closed-field-line flux of the FRC. Experimental and theoretical evidence suggest that the longest-lived FRC's are obtained when the closed flux is maximized. Because the initial ionization is done in the presence of the bias field, the actual bias flux available at the time of application of the main theta-pinch field depends strongly on the initial ionization, or preionization, technique used. In this paper we report on experiments characterizing the previously used theta-pinch preionization technique that employed a net field (bias plus preionization) null, or zero-crossing, of the axial component of the magnetic field to break down the gas. We also discuss results of experiments designed to develop preionization techniques in which the gas breakdown is not accomplished by a zero-crossing.

  7. Origin of irradiations by ionizing radiations

    International Nuclear Information System (INIS)

    Metivier, H.

    1998-01-01

    Irradiations by ionizing radiations proceed from two main sources: the natural radiations from the environment and the sources of 'human' origin, i.e. linked with modern technology. In most countries the irradiation by natural sources remains the most important. The irradiations for medical purposes comes in second position and depends on the degree of technological evolution of the country, and in the last position are the irradiations linked with nuclear industry. The inventory of these irradiations is regularly updated by the Scientific Committee of the United Nations for the study of ionizing radiation effects (UNSCEAR). In France the mean individual irradiation due to natural radioactivity is of 2 mSv per year of efficient dose and can vary with a factor 3 from one region to the other. Irradiation of medical diagnosis origin is of about 1 mSv per year. This paper presents successively: the natural irradiation sources (cosmic radiation, cosmic rays and cosmogenic radionuclides, the Earth's radiations, primary radionuclides and radon), the natural sources modified by the technology (extraction industries, fossil fuels and phosphated ores, aerial transports and space activities, consumer products), the irradiation sources of technological origin (nuclear weapons, electric power production, major accidents, occupational irradiations), and the medical irradiations (diagnosis techniques, radiology, nuclear medicine and therapeutic uses). (J.S.)

  8. Ionizing radiation in 21st century

    International Nuclear Information System (INIS)

    Jaworowski, Zbigniew

    2005-01-01

    The paper begins with the author's personal experience in Poland on the occasion of Chernobyl nuclear accident followed by main lessons that the author could deduce from the accident. After the discovery of ionizing radiation at the end of 19th century, social perception has altered between acceptance and rejection stemming from recognition of the basic aspects: usefulness for medical applications and for technical and scientific aims, beneficial effects of their low levels, and harmful effects of high levels. The author explains how linear no-threshold (LNT) assumption according to which even the lowest, near zero doses of radiation may cause cancer genetic harm has become established. Comparing the natural radioactivity of the earth's crust with the activity of much shorter-lived radioactive wastes from the nuclear power cycle, it is concluded that none of the man-made component of the radioactive wastes has higher-toxicity than the natural Th 232. The paper concludes by stating that one century has not been long enough to adapt mentally to ionizing radiation and radioactivity and perhaps 21st century will suffice for this adaptation. (S. Ohno)

  9. Ionization radiations - basis, risks and benefits

    International Nuclear Information System (INIS)

    Bodart, F.

    1991-01-01

    An attempt is made to discuss the use of ionizing radiations in an impartial way. Ionizing radiation is potentially harmfull; excessive doses have a devastating effect on living cells. However, there is no direct, conclusive evidence of human disability, either in the form of cancer or genetic anomalies, arising as a consequence of low-level doses of x- or gamma-rays of about 0.01 Gray (1 rad) the entire dose range involved in medical radiography or in nuclear industry. Statements appearing in the press that a certain number of excess cancers will be produced are estimates, based maybe on plausible assumptions, but estimates nevertheless; they are not measured quantities or established facts. A balanced view of radiation must include appreciation of the substantial benefits which result from their use in both medicine and industry. The risks are small and hard to demonstrate, and it is instructive to make a comparison with the other hazards occuring continually in an industrialized society, such as driving a motorcar or smoking cigarettes. (Author)

  10. Effects of ionizing radiations on insects

    International Nuclear Information System (INIS)

    Goyffon, Max.

    1978-01-01

    The most traditional effects caused by irradiation are development and morphogenesis disorders since on the whole the sensitivity of the developing organism to ionizing radiations is all the greater as the growth rate is faster. During the development of higher insects two categories of cell divide: larval cells on the one hand, which differentiate immediately after segmentation and give rise to larval organisms, and embryonic cells on the other which divide actively to form various islets or imaginal discs destined, each to its own extent, to provide the organs of the adult. Two cell categories thus coexist in the larva, one undergoing differentiation and the other multiplication, the radiosensitivity of which will be quite different for this very reason and will account at least partly, where the lethal effect of ionizing radiations is concerned, for the results observed. Three chapters deal in turn with effects on longevity, on regeneration and restoration and on morphogenesis and development. Strong doses give rise beyond a certain threshold to the appearance of acute radiodermatitis; their clinical signs and different degrees of seriousness liken them to burns of a special type [fr

  11. Atomic structure investigation of ionized krypton

    International Nuclear Information System (INIS)

    Kotze, P.B.

    1981-12-01

    The experimental lifetimes of ionized Krypton are discussed. Theoretical, the Coulomb approximation proves to be a reliable tool for the performance of calculations in Krypton II, where in general good agreement between experimental and theoretical lifetimes is reached, but its vulnerability is exposed in the case of Krypton III, where only results concerning levels with a 4p 3 ( 4 S 0 ) parent core can be obtained. Although the single configuration Hartree-Fock approximation turns out to be an adequate way of obtaining wave functions of excited states in Krypton III, cancellation effects resulting from configuration-interaction mixing, make the calculated transition probabilities in Krypton II less reliable. Previous work on configuration-interaction effects in the spectrum of Krypton II (El 76a, El 76b) reveals that good agreement between experimental and theoretical results can be obtained. A systematic theoretical analysis based on the multi-configurarion Hartree-Fock approximation to account for configuration-interaction effects should contribute a great deal to the existing knowledge of the energy spectra of ionized atoms

  12. Vinyl acetate polymerization by ionizing radiation

    International Nuclear Information System (INIS)

    Mesquita, Andrea Cercan

    2002-01-01

    The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60 Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

  13. The effects of ionizing radiation on man

    International Nuclear Information System (INIS)

    Watson, G.M.

    1975-08-01

    This paper describes the major effects of ionizing radiation on man and the relationship between such effects and radiation dose, with the conclusion that standards of radiological safety must be based on the carcinogenetic and mutagenic properties of ionizing radiation. Man is exposed to radiation from natural sources and from man-made sources. Exposure from the latter should be regulated but, since there is little observational or experimental evidence for predicting the effects of the very small doses likely to be required for adequate standards of safety, it is necessary to infer them from what is seen at high doses. Because the formal relationship between dose and effect is not fully understood, simplifying assumptions are necessary to estimate the effects of low doses. Two such assumptions are conventionally used; that there is a linear relationship between dose and effect at all levels of dose, and that the rate at which a dose of radiation is given does not alter the magnitude of the effect. These assumptions are thought to be conservative, that is they will not lead to an underestimation of the effects of small radiation doses although they may give an over-estimate. (author)

  14. Measuring ionizing radiation with a mobile device

    Science.gov (United States)

    Michelsburg, Matthias; Fehrenbach, Thomas; Puente León, Fernando

    2012-02-01

    In cases of nuclear disasters it is desirable to know one's personal exposure to radioactivity and the related health risk. Usually, Geiger-Mueller tubes are used to assess the situation. Equipping everyone with such a device in a short period of time is very expensive. We propose a method to detect ionizing radiation using the integrated camera of a mobile consumer device, e.g., a cell phone. In emergency cases, millions of existing mobile devices could then be used to monitor the exposure of its owners. In combination with internet access and GPS, measured data can be collected by a central server to get an overview of the situation. During a measurement, the CMOS sensor of a mobile device is shielded from surrounding light by an attachment in front of the lens or an internal shutter. The high-energy radiation produces free electrons on the sensor chip resulting in an image signal. By image analysis by means of the mobile device, signal components due to incident ionizing radiation are separated from the sensor noise. With radioactive sources present significant increases in detected pixels can be seen. Furthermore, the cell phone application can make a preliminary estimate on the collected dose of an individual and the associated health risks.

  15. MICROWAVE INTERACTIONS WITH INHOMOGENEOUS PARTIALLY IONIZED PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Kritz, A. H.

    1962-11-15

    Microwave interactions with inhomogeneous plasmas are often studied by employing a simplified electromagnetic approach, i.e., by representing the effects of the plasma by an effective dielectric coefficient. The problems and approximations associated with this procedure are discussed. The equation describing the microwave field in an inhomogeneous partially ionized plasma is derived, and the method that is applied to obtain the reflected, transmitted, and absorbed intensities in inhomogeneous plasmas is presented. The interactions of microwaves with plasmas having Gaussian electron density profiles are considered. The variation of collision frequency with position is usually neglected. In general, the assumption of constant collision frequency is not justified; e.g., for a highly ionized plasma, the electron density profile determines, in part, the profile of the electron-ion collision frequency. The effect of the variation of the collision frequency profile on the interaction of microwaves with inhomogeneous plasmas is studied in order to obtain an estimate of the degree of error that may result when constant collision frequency is assumed instead of a more realistic collision frequency profile. It is shown that the degree of error is of particular importance when microwave analysis is used as a plasma diagnostic. (auth)

  16. Ionizing radiation detector using multimode optical fibers

    International Nuclear Information System (INIS)

    Suter, J.J.; Poret, J.C.; Rosen, M.; Rifkind, J.M.

    1993-01-01

    An optical ionizing radiation detector, based on the attenuation of 850-nm light in 50/125-μm multimode fibers, is described. The detector is especially well suited for application on spacecraft because of its small design. The detection element consists of a section of coiled fibers that has been designed to strip higher-order optical modes. Cylindrical radiation shields with atomic numbers ranging from Z = 13 (aluminum too) Z = 82 (lead) were placed around the ionizing radiation detector so that the effectiveness of the detector could be measured. By exposing the shields and the detector to 1.25-MeV cobalt 60 radiation, the mass attenuation coefficients of the shields were measured. The detector is based on the phenomenon that radiation creates optical color centers in glass fibers. Electron spin resonance spectroscopy performed on the 50/125-μm fibers showed the presence of germanium oxide and phosphorus-based color centers. The intensity of these centers is directly related to the accumulated gamma radiation

  17. Detection and measurement of ionizing radiation

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    All detection or measurement of radiation rests in the possibility of recognizing the interactions of radiation with matter. When radiation passes through any kind of material medium, all or a portion of its energy is transferred to this medium. This transferred energy produces an effect in the medium. In principle, the detection of radiation is based on the appearance and the observation of this effect. In theory, all of the effects produced by radiation may be used in detecting it: in practice, the effects most commonly employed are: (1) ionization of gases (gas detectors), or of some chemical substance which is transformed by radiation (photographic or chemical dosimeters); (2) excitations in scintillators or semiconductors (scintillation counters, semiconductor counters); (3) creation of structural defects through the passage of radiation (transparent thermoluminescent and radioluminescent detectors); and (4) raising of the temperature (calorimeters). This study evaluates in detail, instruments based on the ionization of gases and the production of luminescence. In addition, the authors summarize instruments which depend on other forms of interaction, used in radiation medicine and hygiene (radiology, nuclear medicine)

  18. Influence of ionizing radiation on Trypanosoma cruzi

    International Nuclear Information System (INIS)

    Szarota, Rosa Maria

    2006-01-01

    Chagas's disease is one of the major public health problems in South America, promoting high prejudice to the local population. Despite the massive efforts to control it, this disease has no cure and presents puzzling unsolved questions. Considering that many researchers have used ionizing radiation to modify protozoans or biomolecules, we investigated the immunological response aspects of susceptible and resistant mice using irradiated parasites. Low radiation doses preserved the reproductive and invasive capacities of the parasite. Both susceptible and resistant animals, after immunization with irradiated parasites produced specific antibodies. After a challenge, the animals presented low parasitaemia, excepting those immunized with the antigen irradiated with higher doses. Using low radiation doses, we were able to selectively isolate trypomastigotes, leading to an improvement in the quality of the immune response, as previously reported when performing complement system assays. These data highlight the importance of selecting trypomastigote forms for immunization against T. cruz; and point towards ionizing radiation as an alternative to achieve this selection, since when this procedure is performed using complement, the subsequent steps are impaired by the difficulties to remove this component from the system. (author)

  19. Thermionic detector with multiple layered ionization source

    International Nuclear Information System (INIS)

    Patterson, P. L.

    1985-01-01

    Method and apparatus for analyzing specific chemical substances in a gaseous environment comprises a thermionic source formed of multiple layers of ceramic material composition, an electrical current instrumentality for heating the thermionic source to operating temperatures in the range of 100 0 C. to 1000 0 C., an instrumentality for exposing the surface of the thermionic source to contact with the specific chemical substances for the purpose of forming gas phase ionization of the substances by a process of electrical charge emission from the surface, a collector electrode disposed adjacent to the thermiomic source, an instrumentality for biasing the thermionic source at an electrical potential which causes the gas phase ions to move toward the collector, and an instrumentality for measuring the ion current arriving at the collector. The thermionic source is constructed of a metallic heater element molded inside a sub-layer of hardened ceramic cement material impregnated with a metallic compound additive which is non-corrosive to the heater element during operation. The sub-layer is further covered by a surface-layer formed of hardened ceramic cement material impregnated with an alkali metal compound in a manner that eliminates corrosive contact of the alkali compounds with the heater element. The sub-layer further protects the heater element from contact with gas environments which may be corrosive. The specific ionization of different chemical substances is varied over a wide range by changing the composition and temperature of the thermionic source, and by changing the composition of the gas environment

  20. Fog camera to visualize ionizing charged particles

    International Nuclear Information System (INIS)

    Trujillo A, L.; Rodriguez R, N. I.; Vega C, H. R.

    2014-10-01

    The human being can not perceive the different types of ionizing radiation, natural or artificial, present in the nature, for what appropriate detection systems have been developed according to the sensibility to certain radiation type and certain energy type. The objective of this work was to build a fog camera to visualize the traces, and to identify the trajectories, produced by charged particles with high energy, coming mainly of the cosmic rays. The origin of the cosmic rays comes from the solar radiation generated by solar eruptions where the protons compose most of this radiation. It also comes, of the galactic radiation which is composed mainly of charged particles and gamma rays that comes from outside of the solar system. These radiation types have energy time millions higher that those detected in the earth surface, being more important as the height on the sea level increases. These particles in their interaction produce secondary particles that are detectable by means of this cameras type. The camera operates by means of a saturated atmosphere of alcohol vapor. In the moment in that a charged particle crosses the cold area of the atmosphere, the medium is ionized and the particle acts like a condensation nucleus of the alcohol vapor, leaving a visible trace of its trajectory. The built camera was very stable, allowing the detection in continuous form and the observation of diverse events. (Author)