WorldWideScience

Sample records for above-threshold ionization ati

  1. Measurement of intensity-dependent rates of above-threshold ionization (ATI) of atomic hydrogen at 248 nm

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, T.D.

    1991-04-01

    Measured rates of multiphoton ionization (MPI) from the ground state of atomic hydrogen by a linearly polarized, subpicosecond KrF laser pulse at 248 nm wavelength are compared to predictions of lowest-order perturbation theory, Floquet theory, and Keldysh-Faisal-Reiss (KFR) theory with and without Coulomb correction for peak irradiance of 3 {times} 10{sup 12}W/cm{sup 2} to 2 {times} 10{sup 14}W/cm{sup 2}. The Coulomb-corrected Keldysh model falls closest to the measured rates, the others being much higher or much lower. At 5 {times} 10{sup 13}W/cm{sup 2}, the number of ATI electrons decreased by a factor of approximately 40 with each additional photon absorbed. ATI of the molecular hydrogen background and of atoms from photodissociation of the molecules were also observed. The experiment employed a crossed-beam technique at ultrahigh vacuum with an rf-discharge atomic hydrogen source and a magnetic-bottle type electron time-of-flight spectrometer to count the electrons in the different ATI channels separately. The apparatus was calibrated to allow comparison of absolute as well as relative ionization rates to the theoretical predictions. This calibration involved measuring the distribution of irradiance in a focal volume that moved randomly and changed its size from time to time. A data collection system under computer control divided the time-of-flight spectra into bins according to the energy of each laser pulse. This is the first measurement of absolute rates of ATI in atomic hydrogen, and the first measurement of absolute test of MPI in atomic hydrogen without a large factor to account for multiple modes in the laser field. As such, the results of this work are important to the development of ATI theories, which presently differ by orders of magnitude in their prediction of the ionization rates. They are also important to recent calculations of temperatures in laser-heated plasmas, many of which incorporate KFR theory.

  2. Modeling strong-field above-threshold ionization

    International Nuclear Information System (INIS)

    Sundaram, B.; Armstrong, L. Jr.

    1990-01-01

    Above-threshold ionization (ATI) by intense, short-pulse lasers is studied numerically, using the stretched hydrogen atom Hamiltonian. Within our model system, we isolate several mechanisms that contribute to the ATI process. These mechanisms, which involve both excited bound states and continuum states, all invoke intermediate, off-energy shell transitions. In particular, the importance of excited bound states and off-energy shell bound-free processes to the ionization mechanism are shown to relate to a simple physical criterion. These processes point to importance differences in the interpretation of ionization characteristics for short pulses from that for longer pulses. Our analysis concludes that although components of ATI admit of simple, few-state modeling, the ultimate synthesis points to a highly complex mechanism

  3. Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2

    DEFF Research Database (Denmark)

    Wu, J.; Kunitski, M.; Pitzer, M.

    2013-01-01

    We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple...... diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles....

  4. Two-color above-threshold ionization of atoms and ions in XUV Bessel beams and intense laser light

    Science.gov (United States)

    Seipt, D.; Müller, R. A.; Surzhykov, A.; Fritzsche, S.

    2016-11-01

    The two-color above-threshold ionization (ATI) of atoms and ions is investigated for a vortex Bessel beam in the presence of a strong near-infrared (NIR) light field. While the photoionization is caused by the photons from the weak but extreme ultraviolet (XUV) vortex Bessel beam, the energy and angular distribution of the photoelectrons and their sideband structure are affected by the plane-wave NIR field. We here explore the energy spectra and angular emission of the photoelectrons in such two-color fields as a function of the size and location of the target atoms with regard to the beam axis. In addition, analog to the circular dichroism in typical two-color ATI experiments with circularly polarized light, we define and discuss seven different dichroism signals for such vortex Bessel beams that arise from the various combinations of the orbital and spin angular momenta of the two light fields. For localized targets, it is found that these dichroism signals strongly depend on the size and position of the atoms relative to the beam. For macroscopically extended targets, in contrast, three of these dichroism signals tend to zero, while the other four just coincide with the standard circular dichroism, similar as for Bessel beams with a small opening angle. Detailed computations of the dichroism are performed and discussed for the 4 s valence-shell photoionization of Ca+ ions.

  5. Tunneling-induced shift of the cutoff law for high-order above-threshold ionization

    International Nuclear Information System (INIS)

    Lai, X. Y.; Quan, W.; Liu, X.

    2011-01-01

    We investigate the cutoff law for high-order above-threshold ionization (HATI) within a semiclassical framework. By explicitly adopting the tunneling effect and considering the initial position shift of the tunneled electron from the origin in the model, the cutoff energy position in HATI spectrum exhibits a well-defined upshift from the simple-man model prediction. The comparison between numerical results from our improved semiclassical model and the quantum-orbit theory shows a good agreement for small values of the Keldysh parameter γ, implying the important role of the inherent quantum tunneling effect in HATI dynamics.

  6. Alignment dependence in above-threshold ionization of H2+: role of intermediate resonances

    DEFF Research Database (Denmark)

    Hernández, Jorge Fernández; Madsen, Lars Bojer

    2009-01-01

    We report a 3D ab initio investigation of the dependence of above-threshold ionization of the H2+ molecule on the orientation of a linearly polarized intense femtosecond laser pulse with respect to the molecular axis. The calculations were performed in the frozen nuclei approximation for the 2Σ+g(1...

  7. Photo double ionization of helium 100 eV and 450 eV above threshold: II. Circularly polarized light

    International Nuclear Information System (INIS)

    Knapp, A; Kheifets, A; Bray, I; Weber, Th; Landers, A L; Schoessler, S; Jahnke, T; Nickles, J; Kammer, S; Jagutzki, O; Schmidt, L Ph H; Schoeffler, M; Osipov, T; Prior, M H; Schmidt-Boecking, H; Cocke, C L; Doerner, R

    2005-01-01

    We present a joint experimental and theoretical study of the fully differential cross section of the photo double ionization of helium with left and right circularly polarized light at E exc = 100 eV and 450 eV above the threshold. We analyse angular distributions for the slow electron and the normalized circular dichroism for various energy sharings of the excess energy between the two electrons. The experimental results are well reproduced by convergent close coupling calculations

  8. Photo double ionization of helium 100 eV and 450 eV above threshold: I. Linearly polarized light

    International Nuclear Information System (INIS)

    Knapp, A; Kheifets, A; Bray, I; Weber, Th; Landers, A L; Schoessler, S; Jahnke, T; Nickles, J; Kammer, S; Jagutzki, O; Schmidt, L Ph H; Schoeffler, M; Osipov, T; Prior, M H; Schmidt-Boecking, H; Cocke, C L; Doerner, R

    2005-01-01

    We present a joint experimental and theoretical study for the fully differential cross section of the photo double ionization (PDI) of helium with linearly polarized light at the excess energies E exc = 100 eV and 450 eV above the threshold. The fully differential cross section is obtained by measuring the three-dimensional momentum vectors of one electron and the He 2+ ion in coincidence using the COLTRIMS method. We give an overview of the momentum distribution of the three-body continuum 100 eV above the threshold. We show angular distributions for both electrons for various energy sharings at E exc = 100 eV and 450 eV. The experimental results are well reproduced by a set of convergent close-coupling (CCC) calculations

  9. Photo double ionization of helium 100 eV and 450 eV above threshold: III. Gerade and ungerade amplitudes and their relative phases

    International Nuclear Information System (INIS)

    Knapp, A; Kraessig, B; Kheifets, A; Bray, I; Weber, Th; Landers, A L; Schoessler, S; Jahnke, T; Nickles, J; Kammer, S; Jagutzki, O; Schmidt, L Ph H; Schoeffler, M; Osipov, T; Prior, M H; Schmidt-Boecking, H; Cocke, C L; Doerner, R

    2005-01-01

    We present a joint experimental and theoretical study of the gerade and ungerade amplitudes of the photo double ionization of helium at excess energies of 100 eV and 450 eV above the threshold. We describe a method of extracting the amplitudes from a COLTRIMS data set. The experimental results are well reproduced by convergent close-coupling (CCC) calculations. The fully differential cross section data underlying this study can be found in our companion papers immediately preceding this one

  10. High-order above-threshold dissociation of molecules

    Science.gov (United States)

    Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

    2018-03-01

    Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

  11. EnableATIS strategy assessment.

    Science.gov (United States)

    2014-02-01

    Enabling Advanced Traveler Information Systems (EnableATIS) is the traveler information component of the Dynamic Mobility Application (DMA) program. The objective of : the EnableATIS effort is to foster transformative traveler information application...

  12. Above-threshold ionization and laser-induced electron diffraction in diatomic molecules

    Czech Academy of Sciences Publication Activity Database

    Suarez, N.; Chacon, A.; Ciappina, Marcelo F.; Wolter, B.; Biegert, J.; Lewenstein, M.

    2016-01-01

    Roč. 94, č. 4 (2016), s. 1-19, č. článku 043423. ISSN 2469-9926 R&D Projects: GA MŠk LQ1606; GA MŠk EF15_008/0000162 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : high-harmonic interferometry * strong-field approximation * wave packets * generation * dynamics * atom * orbitals * pulse Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.925, year: 2016

  13. Empirically Based Myths: Astrology, Biorhythms, and ATIs.

    Science.gov (United States)

    Ragsdale, Ronald G.

    1980-01-01

    A myth may have an empirical basis through chance occurrence; perhaps Aptitude Treatment Interactions (ATIs) are in this category. While ATIs have great utility in describing, planning, and implementing instruction, few disordinal interactions have been found. Article suggests narrowing of ATI research with replications and estimates of effect…

  14. Contribution of GIS to ATIS

    OpenAIRE

    Kwan, Mei-Po; Golledge, Reginald G.

    1994-01-01

    Transportation planning has been turning away from the solutions of building highways and transit routes to changing people's travel choices and making more efficient use of existing facilities. With the recent research focus on Advanced Traveler Information Systems (ATIS), it is imperative to understand the travel behavior of people and the information required to change their travel choices.

  15. Dynamics of dissociation versus ionization in strong laser fields

    International Nuclear Information System (INIS)

    In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10 11-14 W/cm 2 with the fundamental and second harmonic of a ND:YAG or ND:YLF laser system. Measurements include energy resolved electron and mass spectroscopy which provide useful probes in elucidating the interaction dynamics predicted by existing models. The example this in this paper, examines the strong-field dissociation of H 2 + , HD + , and D 2 + at green (0.5 μm) and (1μm) frequencies. The diatomic ions are formed via multiphonon ionization of the neutral precursor which is physically separable from the dissociation process. This study provides the first observation of the dynamics associated with the above threshold dissociation (ATD) process and analogies will be made with the more familiar above threshold ionization (ATI) phenomenon

  16. AMD ja ATI kolivad kokku / Kalle Kose

    Index Scriptorium Estoniae

    Kose, Kalle

    2006-01-01

    Maailma suuruselt teise personaalarvutite protsessorite valmistaja Advanced Micro Devices (AMD) liitumisest graafikakaartide tootja ATI Technologies'iga (ATI). Vt. ka: 5 küsimust AMD-le. Küsimustele vastab AMD regiooni esindaja Stockholmis Martin Sjögren

  17. Simulation of the Optimized Structure of a Laterally Coupled Distributed Feedback (LC-DFB Semiconductor Laser Above Threshold

    Directory of Open Access Journals (Sweden)

    M. Seifouri

    2013-10-01

    Full Text Available In this paper, the laterally coupled distributed feedback semiconductor laser is studied. In the simulations performed, variations of structural parameters such as the grating amplitude a, the ridge width W, the thickness of the active region d, and other structural properties are considered. It is concluded that for certain values ​​of structural parameters, the laser maintains the highest output power, the lowest distortion Bragg frequency δL and the smallest changes in the wavelength λ. Above threshold, output power more than 40mW and SMSR values greater than 50 dB were achieved.

  18. Distributions of extreme bursts above thresholds in a fractional Lévy toy model of natural complexity.

    Science.gov (United States)

    Watkins, Nicholas; Chapman, Sandra; Rosenberg, Sam; Credgington, Dan; Sanchez, Raul

    2010-05-01

    In 2 far-sighted contributions in the 1960s Mandelbrot showed the ubiquity of both non-Gaussian fluctuations and long-ranged temporal memory (the "Noah" and "Joseph" effects, respectively) in the natural and man-made worlds. Much subsequent work in complexity science has contributed to the physical underpinning of these effects, particularly in cases where complex interactions in a system cause a driven or random perturbation to be nonlinearly amplified in amplitude and/or spread out over a wide range of frequencies. In addition the modelling of catastrophes has begun to incorporate the insights which these approaches have offered into the likelihood of extreme and long-lived fluctuations. I will briefly survey how the application of the above ideas in the earth system has been a key focus and motivation of research into natural complexity at BAS [e.g. Watkins & Freeman, Science, 2008; Edwards et al, Nature, 2007]. I will then discuss in detail a standard toy model (linear fractional stable motion, LFSM) which combines the Noah and Joseph effects in a controllable way and explain how it differs from the widely used continuous time random walk. I will describe how LFSM is being used to explore the interplay of the above two effects in the distribution of bursts above thresholds. I will describe ongoing work to improve the accuracy of maximum likelihood-based estimation of burst size and waiting time distributions for LFSM first reported in [Watkins et al, PRE, 2009]; and will also touch on similar work for multifractal models [Watkins et al, PRL comment, 2009].

  19. 47 CFR 25.281 - Automatic Transmitter Identification System (ATIS).

    Science.gov (United States)

    2010-10-01

    ...) The protocol shall be International Morse Code keyed by a 1200 Hz ±800 Hz tone representing a mark and... code programmed into the ATIS device in a permanent manner such that it cannot be readily changed by...

  20. The Higgs portal above threshold

    Energy Technology Data Exchange (ETDEWEB)

    Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Lou, Hou Keong [Department of Physics, Princeton University,Princeton, NJ 08540 (United States); McCullough, Matthew [Theory Division, CERN,1211 Geneva 23 (Switzerland); Thalapillil, Arun [Department of Physics and Astronomy, Rutgers University,Piscataway, NJ 08854 (United States)

    2016-02-18

    The discovery of the Higgs boson opens the door to new physics interacting via the Higgs Portal, including motivated scenarios relating to baryogenesis, dark matter, and electroweak naturalness. We systematically explore the collider signatures of singlet scalars produced via the Higgs Portal at the 14 TeV LHC and a prospective 100 TeV hadron collider. We focus on the challenging regime where the scalars are too heavy to be produced in the decays of an on-shell Higgs boson, and instead are produced primarily via an off-shell Higgs. Assuming these scalars escape the detector, promising channels include missing energy in association with vector boson fusion, monojets, and top pairs. We forecast the sensitivity of searches in these channels at √s=14 & 100 TeV and compare collider reach to the motivated parameter space of singlet-assisted electroweak baryogenesis, Higgs Portal dark matter, and neutral naturalness.

  1. Impact of Coulomb potential on peak structures arising in momentum and low-energy photoelectron spectra produced in strong-field ionization of laser-irradiated atoms

    Science.gov (United States)

    Pyak, P. E.; Usachenko, V. I.

    2018-03-01

    The phenomenon of pronounced peak structure(s) of longitudinal momentum distributions as well as a spike-like structure of low-energy spectra of photoelectrons emitted from laser-irradiated Ar and Ne atoms in a single ionization process is theoretically studied in the tunneling and multiphoton regimes of ionization. The problem is addressed assuming only the direct above-threshold ionization (ATI) as a physical mechanism underlying the phenomenon under consideration (viz. solely contributing to observed photoelectron momentum distributions (PMD)) and using the Coulomb-Volkov (CV) ansatz within the frame of conventional strong-field approximation (SFA) applied in the length-gauge formulation. The developed CV-SFA approach also incorporates the density functional theory essentially exploited for numerical composition of initial (laser-free) atomic state(s) constructed from atomic orbitals of Gaussian type. Our presented CV-SFA based (and laser focal-volume averaged) calculation results proved to be well reproducing both the pronounced double-peak and/or ATI-like multi-peak structure(s) experimentally observed in longitudinal PMD under conditions of tunneling and/or multiphoton regime, respectively. In addition, our CV-SFA results presented for tunneling regime also suggest and remarkably reproduce a pronounced structure observed in relevant experiments as a ‘spike-like’ enhanced maximum arising in low-energy region (around the value of about 1 eV) of photoelectron spectra. The latter consistency allows to identify and interpret these results as the so-called low-energy structure (LES) since the phenomenon proved to appear as the most prominent if the influence of Coulomb potential on photoelectron continuum states is maximally taken into account under calculations (viz. if the parameter Z in CV’s functions is put equal to 1). Moreover, the calculated LES proved to correspond (viz., established as closely related) to the mentioned double-peak structure arising

  2. A psychometric analysis of the Approaches to Teaching Inventory (ATI and a proposal for a Spanish version (S-ATI-20

    Directory of Open Access Journals (Sweden)

    Fuensanta Monroy

    2015-01-01

    Full Text Available Background: Recent educational research has explored how university teachers approach their teaching. One of the most widely used instruments is Trigwell and Prosser's (2004 Approaches to Teaching Inventory (ATI. There is, however, scarce research on the Spanish version of this questionnaire. This paper aimed: 1 to analyse the reliability and structural validity of two existing versions of ATI in Spanish language, and 2 to present a proposal for a new Spanish version of ATI, and to measure its reliability and validity. Method: The samples comprised university and trainee teachers from two Spanish universities. Results: Reliability coefficients, factor structures, and item loadings of the two existing Spanish versions of ATI were evaluated. Some coincidental outcomes suggested that a revised ATI in Spanish was required, thus a new version (S-ATI-20 was presented and tested on a new sample. Conclusions: The results suggest questionnaires should be suitably translated and item wording carefully adapted. Factor analyses moderately support a two-scale model, but a lack of correlation between approaches suggests alternative approaches to teaching models might be worth considering. This paper presents preliminary results which should be taken with caution, but S-ATI-20 may serve as a tool for self-reflection in faculty development.

  3. Spin and Angular Momentum in Strong-Field Ionization

    Science.gov (United States)

    Trabert, D.; Hartung, A.; Eckart, S.; Trinter, F.; Kalinin, A.; Schöffler, M.; Schmidt, L. Ph. H.; Jahnke, T.; Kunitski, M.; Dörner, R.

    2018-01-01

    The spin polarization of electrons from multiphoton ionization of Xe by 395 nm circularly polarized laser pulses at 6 ×1013 W /cm2 has been measured. At this photon energy of 3.14 eV the above-threshold ionization peaks connected to Xe+ ions in the ground state (J =3 /2 , ionization potential Ip=12.1 eV ) and the first excited state (J =1 /2 , Ip=13.4 eV ) are clearly separated in the electron energy distribution. These two combs of above-threshold ionization peaks show opposite spin polarizations. The magnitude of the spin polarization is a factor of 2 higher for the J =1 /2 than for the J =3 /2 final ionic state. In turn, the data show that the ionization probability is strongly dependent on the sign of the magnetic quantum number.

  4. Dynamic mobility applications policy analysis : policy and institutional issues for enabling advanced traveler information services (EnableATIS).

    Science.gov (United States)

    2014-10-01

    This report documents policy considerations for Enabling Advanced Traveler Information Services, or EnableATIS. : EnableATIS is the traveler information element of the Dynamic Mobility Applications program, and it provides a framework to : develop mu...

  5. Advanced Traveler Information Systems (ATIS) 2.0 Precursor System: Final Report

    Science.gov (United States)

    2018-03-01

    Advanced Traveler Information Systems (ATIS) have experienced significant growth since their initial inception in the 1990s. Technologies have continued to evolve at a rapid pace, enabling the integration of advanced solutions for traveler informatio...

  6. Implantation of individual temporary warehouse (ATI) CN irradiated fuel Asco; Implantacion del Almacen Temporal Individualizado (ATI) de combustible irradiado de CN Asco

    Energy Technology Data Exchange (ETDEWEB)

    Estrampes, J.

    2014-07-01

    The operation of the two units of Asco NPP produces the filling of the available positions of the Spent Fuel. Nowadays, the situation in terms of occupation is about 90% then the ATI becomes more than necessary to continue the operation of the next cycles white the Centralized Storage (State level being not available. This article describes the process since the design to construction of the ATI at Asco Nuclear Power Plant and describes the most important criteria to classify the fuel and the inserts as approved contents in order to be loaded into the storage containers prior to be sent to the future ATC. (Author)

  7. The Implementation of Aptitude Treatment Interaction (ATI to Improve Learning Motivation of Low Achievement Students

    Directory of Open Access Journals (Sweden)

    Syawal - Syawal

    2017-10-01

    Full Text Available This research was classroom action research, which aims at improving students' motivation of their poor performance through learning model Aptitude Treatment Interaction (ATI on VII.3 grade students of SMP Negeri 6 Parepare. Aptitude Treatment Interaction (ATI can serve individual student differences by adjusting treatment or learning method with students' abilities. The use of this model was emphasizing to create small groups of students that have achievement alike. Students with have low academic achievement based on test results and teacher interview will be grouped into one group and will be given preferential treatment by tutoring intensity rather than the group of high academic achievement. Subjects of this research were students of class VII.3 SMP Negeri 6 Parepare which is consist of 25 students. This research was conducted in two cycles. The procedure of this research involved four phases: (1 planning, (2 Implementation of action, (3 observation, (4 Reflection. The data collection was done by observation, tests, and questionnaires for each cycle after giving treatment through learning model Aptitude Treatment Interaction (ATI. Data collected were analyzed using quantitative and qualitative analysis. The results of this research indicate that the Aptitude Treatment Interaction (ATI can be an alternative method to improve learning motivation of low achievement students. The results of this research also showed that the Aptitude Treatment Interaction (ATI can be an alternative to problem-solving in the classroom, especially for low achievement students.

  8. Advanced Traveler Information Systems and Commercial Vehicle Operations Components of the Intelligent Transportation Systems: On-road Evaluation of ATIS Messages

    Science.gov (United States)

    1998-03-01

    This report describes the results of an on-road study that examined how Advanced Traveler Information Systems (ATIS) information influences driver behavior. The objective of the study was to develop ATIS design guidelines, primarily for In-Vehicle Si...

  9. Vision and operational concept for enabling advanced traveler information services : market readiness assessment (EnableATIS).

    Science.gov (United States)

    2012-05-01

    The purpose of this market readiness assessment is to identify next steps for USDOT to research, demonstrate and advance the objectives of EnableATIS. This will include demonstrating those key concepts that will be within the USDOT and agency sphere ...

  10. A next generation advanced traveler information precursor system (ATIS 2.0 precursor system) use cases report.

    Science.gov (United States)

    2017-05-01

    Advanced Traveler Information Systems (ATIS) have experienced significant growth since their initial inception in the 1990s. Technologies have continued to evolve at a rapid pace, enabling the integration of advanced solutions for traveler informatio...

  11. Impact Of ATIS On Drivers' Decisions And Route Choice: A Literature Review

    OpenAIRE

    Abedel-aty, Mohamed A.; Vaughn, Kenneth M.; Kitamura, Ryuichi; Jovanis, Paul P.

    1993-01-01

    This report reviews the recent studies adopted in order to understand drivers' behavior, and in particular, behavior when influenced by an Advanced Traveler Information System (ATIS). Different approaches were used in these studies: field experiments, route choice surveys, interactive computer simulation games, route choice simulation and/or modeling, and stated preference. These studies are classified according to the main approach used, and the main objective, method, and findings are prese...

  12. The calculation of photoelectron angular distributions with jet-like structure from scattering theory

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jingtao [Laboratory for High Intensity Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, PO Box 800-211, Shanghai (China); Zhang Wenqi [Laboratory for High Intensity Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, PO Box 800-211, Shanghai (China); Xu Zhizhan [Laboratory for High Intensity Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, PO Box 800-211, Shanghai (China); Li Xiaofeng [Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing (China); Fu Panming [Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing (China); Guo Dongsheng [Department of Physics, Southern University and A and M College, Baton Rouge, LA (United States); Freeman, R R [Department of Applied Science, University of California-Davis, Davis, CA (United States)

    2002-12-14

    Photoelectron angular distributions produced in above-threshold ionization (ATI) are analysed using a nonperturbative scattering theory. The numerical results are in good qualitative agreement with recent measurements. Our study shows that the origin of the jet-like structure arises from the inherent properties of the ATI process and not from the angular momentum of either the initial or the excited states of the atom.

  13. Pseudo-random number generators for Monte Carlo simulations on ATI Graphics Processing Units

    Science.gov (United States)

    Demchik, Vadim

    2011-03-01

    Basic uniform pseudo-random number generators are implemented on ATI Graphics Processing Units (GPU). The performance results of the realized generators (multiplicative linear congruential (GGL), XOR-shift (XOR128), RANECU, RANMAR, RANLUX and Mersenne Twister (MT19937)) on CPU and GPU are discussed. The obtained speed up factor is hundreds of times in comparison with CPU. RANLUX generator is found to be the most appropriate for using on GPU in Monte Carlo simulations. The brief review of the pseudo-random number generators used in modern software packages for Monte Carlo simulations in high-energy physics is presented.

  14. Antički opekarski pečati iz fundusa muzeja grada Šibenika

    OpenAIRE

    Pedišić, Ivan; Podrug, Emil

    2008-01-01

    U članku se govori o opekarskim radioničkim pečatima Antičke zbirke Muzeja grada Šibenika. Iz kataloškoga i statističkoga pregleda proizlazi da na nalazištima šibensko-skradinskoga područja u velikome postotku prevladavaju uvozne sjevernojadranske tegule, a među njima se brojčano ističu pečati carske radionice Pansiane. Domaća je proizvodnja zastupljena vojnim proizvodima burnumskih legija, XI. i IV, te s nekoliko proizvoda dosad nepoznatih, vjerojatno lokalnih, rad...

  15. Urinary NGAL Ratio Is Not a Sensitive Biomarker for Monitoring Acute Tubular Injury in Kidney Transplant Patients: NGAL and ATI in Renal Transplant Patients

    Directory of Open Access Journals (Sweden)

    Jessica K. Kaufeld

    2012-01-01

    Full Text Available Urinary neutrophil gelatinase-associated lipocalin (uNGAL is known to predict the prolonged delayed graft function after kidney transplantation. We examined the relation of uNGAL with histological findings of acute tubular injury (ATI. Analyses were made in biopsies taken at 6 weeks, 3 months, and 6 months after kidney transplantation. uNGAL was measured in the spot urines, normalized to urinary creatinine excretion, and correlated to biopsy findings and clinical, laboratory, and demographic variables. Controls included healthy individuals, individuals after kidney donation and ICU patients with acute kidney failure. Renal transplant recipients without ATI did not display elevated uNGAL levels compared to the healthy controls. Transplant patients with ATI had a higher uNGAL excretion at 6 weeks than patients without ATI (27,435 versus 13,605 ng/g; P=0.031. This increase in uNGAL was minor compared to ICU patients with acute renal failure (2.05×106 ng/g. Patients with repeated findings of ATI or severe ATI did not have higher urinary NGAL levels compared to those with only one ATI finding or moderate ATI. Female recipient gender and urinary tract infection were identified as potential confounders. uNGAL has a relation with histological signs of acute tubular injury. The usability of this biomarker in renal allograft recipients is limited because of the low sensitivity.

  16. Retrieving current and wind vectors from ATI SAR data: airborne evidence and inversion strategy

    Science.gov (United States)

    Martin, Adrien; Gommenginger, Christine; Chapron, Bertrand; Marquez, José; Doody, Sam

    2017-04-01

    Conventional and along-track interferometric (ATI) Synthetic Aperture Radar (SAR) sense the motion of the ocean surface by measuring the Doppler shift of reflected signals. Together with the water displacement associated with ocean currents, the SAR measurements are also affected by a Wind-wave induced Artefact Surface Velocity (WASV) caused by the velocity of Bragg scatterers and the orbital velocity of ocean surface gravity waves. The WASV has been modelled theoretically in past studies but has been estimated empirically only once using Envisat ASAR. Here we propose, firstly, to evaluate this WASV from airborne ATI SAR data, secondly, to validate the airborne retrieved surface current after correction of the WASV against HF radar measurements and thirdly to examine the best inversion strategy for a an Ocean Surface Current (OSC) satellite mission to retrieve accurately both the ocean surface current vector (OSCV) and the wind vector in the frame of an OSC satellite mission. The airborne ATI SAR data were acquired in the tidally dominated Irish Sea using a Wavemill-type dual-beam SAR interferometer. A comprehensive collection of airborne Wavemill data acquired in a star pattern over a well-instrumented site made it possible to estimate the magnitude and dependence on azimuth and incidence angle of the WASV. The airborne results compare favourably with those reported for Envisat ASAR, empirical model, which has been used to correct for it. Validation of the current retrieval capabilities of the proof-of-concept has been conducted against HF radar giving a precisions typically better than 0.1 m/s for surface current speed and 7° for direction. Comparisons with POLCOMS (1.8 km) indicate that the model reproduces well the overall temporal evolution but does not capture the high spatial variability of ocean surface currents at the maximum ebb flow. Airborne retrieved currents highlight a short-scale spatial variability up to 100m related to bathymetry channels, which

  17. Microstructure and mechanical properties of the superalloy ATI Allvac 718Plus

    International Nuclear Information System (INIS)

    Zickler, Gerald A.; Schnitzer, Ronald; Radis, Rene; Hochfellner, Rainer; Schweins, Ralf; Stockinger, Martin; Leitner, Harald

    2009-01-01

    ATI Allvac 718Plus is a novel nickel-based superalloy, which was designed for heavy-duty applications in aerospace turbines. In the present study the high-resolution investigation techniques, atom probe tomography, electron microscopy and in situ high-temperature small-angle neutron scattering were used for a comprehensive microstructural characterization. The alloy contains nanometer-sized spherical γ' phase precipitates (Ni 3 (Al,Ti)) and plate-shaped δ phase precipitates (Ni 3 Nb) of micrometer size. The precipitation kinetics of the γ' phase can be described by a classical model for coarsening. The precipitation strongly influences the mechanical properties and is of high scientific and technological interest.

  18. Top quark mass measurements at and above threshold at CLIC

    CERN Document Server

    Seidel, Katja; Tesar, Michal; Poss, Stephane

    2013-01-01

    We present a study of the expected precision of the top quark mass determination, measured at a linear $e^+e^-$ collider based on CLIC technology. GEANT4-based detector simulation and full event reconstruction including realistic physics and beam-induced background levels are used. Two different techniques to measure the top mass are studied: The direct reconstruction of the invariant mass of the top quark decay products and the measurement of the mass together with the strong coupling constant in a threshold scan, in both cases including first studies of expected systematic uncertainties. For the direct reconstruction, experimental uncertainties around 100 MeV are achieved, which are at present not matched by a theoretical understanding on a similar level. With a threshold scan, total uncertainties of around 100 MeV are achieved, including theoretical uncertainties in a well-defined top mass scheme. For the threshold scan, the precision at ILC is also studied to provide a comparison of the two linear collide...

  19. 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

  20. Weldability of superalloys alloy 718 and ATI {sup registered} 718Plus trademark. A study performed by Varestraint testing

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsson, Jonny [The Production Technology Centre Univ. West, Trollhaettan (Sweden). GKN Aerospace Sweden; Chalmers Univ. of Technology, Gothenburg (Sweden). Dept. of Industrial and Material Science; Andersson, Joel [The Production Technology Centre Univ. West, Trollhaettan (Sweden). Dept. of Engineering Science; Brederholm, Anssi; Haenninen, Hannu [Aalto Univ., Helsinki (Finland). Dept. of Engineering Design and Production

    2017-11-01

    In this study, the old and well-known alloy 718 is compared with the newly developed ATI {sup registered} 718Plus trademark from the weldability point of view. This is done in order to gain new information that have not been documented and established yet among the high-temperature materials with high strength, oxidation resistance, thermal stability and sufficient weldability, yet. ATI {sup registered} 718Plus trademark shows a lower sensitivity to hot cracking than alloy 718 with approximately 10 mm total crack length (TCL) difference in Varestraint testing. In the solution-annealed condition at 982 C for 4.5 h followed by air cooling, the crack sensitivity is decreased as compared to the mill-annealed condition. Along the crack path and also ahead of the crack tip, γ-Laves eutectic is present in both alloys. The microhardness measurements showed similar hardness level of 250 HV in the weld metal of both alloys and even in the parent material of alloy 718. ATI {sup registered} 718Plus trademark parent metal had hardness of 380 HV and a small increase of less than 50 HV was observed for both studied alloys in the heat affected zone (HAZ). For the same grain size of ATI {sup registered} 718Plus trademark (8.3 μm) and alloy 718 (15.6 μm), the susceptibility to liquation cracking may increase with increasing grain size. With a small grain size, there is a possibility to accommodate more trace elements (B, S, P) due to the larger grain boundary area. The impurity elements were found in relatively small precipitates, typically borides (0.2 μm), phosphides (0.1 to 0.5 μm) and carbo-sulphides. The solidification sequence of alloy 718 and ATI {sup registered} 718Plus trademark is relatively similar, where the liquid starts to solidify as γ-phase followed by γ/MC reaction at about 1260 C and then final γ/Laves eutectic reaction at around 1150 C. Detailed knowledge about weldability of alloy 718 and ATI {sup registered} 718Plus trademark can be used for material

  1. Advanced traveler information systems (ATIS) : development and testing of a surveillance and delay advisory system for rural areas, and evaluation of satellite communications system for mayday applications

    Science.gov (United States)

    1999-04-01

    In early 1993, the Federal Highway Administration (FHWA) initiated a comprehensive study of rural applications of Advanced Traveler Information Systems (ATIS). The study objectives were to guide Federal programs with respect to Intelligent Transporta...

  2. Nanocluster ionization energies and work function of aluminum, and their temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Avik; Kresin, Vitaly V. [Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484 (United States)

    2015-10-28

    Ionization threshold energies of Al{sub n} (n = 32-95) nanoclusters are determined by laser ionization of free neutral metal clusters thermalized to several temperatures in the range from 65 K to 230 K. The photoion yield curves of cold clusters follow a quadratic energy dependence above threshold, in agreement with the Fowler law of surface photoemission. Accurate data collection and analysis procedures make it possible to resolve very small (few parts in a thousand) temperature-induced shifts in the ionization energies. Extrapolation of the data to the bulk limit enables a determination of the thermal shift of the polycrystalline metal work function, found to be in excellent agreement with theoretical prediction based on the influence of thermal expansion. Small clusters display somewhat larger thermal shifts, reflecting their greater susceptibility to thermal expansion. Ionization studies of free size-resolved nanoclusters facilitate understanding of the interplay of surface, electronic, and lattice properties under contamination-free conditions.

  3. Detection of Ground Moving Targets for Two-Channel Spaceborne SAR-ATI

    Directory of Open Access Journals (Sweden)

    Cai Bin

    2010-01-01

    Full Text Available Many present spaceborne synthetic aperture radar (SAR systems are constrained to only two channels for ground moving target indication (GMTI. Along-track interferometry (ATI technique is currently exploited to detect slowly moving targets and measure their radial velocity and azimuth real position. In this paper, based on the joint probability density function (PDF of interferogram's phase and amplitude and the two hypotheses "clutter" and "clutter plus signal", several constant false alarm rate (CFAR detection criteria are analyzed for their capabilities and limitations under low signal-to-clutter ratio (SCR and low clutter-to-noise ratio (CNR conditions. The CFAR detectors include one-step CFAR detector with interferometric phase, two-step CFAR detectors, and two-dimensional (2D CFAR detector. The likelihood ratio test (LRT based on the Neyman-Pearson (NP criterion is exploited as an upper bound for the performance of the other CFAR detectors. Performance analyses demonstrate the superiority of the 2D CFAR techniques to detect dim slowly moving targets for spaceborne system.

  4. Detection of Ground Moving Targets for Two-Channel Spaceborne SAR-ATI

    Directory of Open Access Journals (Sweden)

    Diannong Liang

    2010-01-01

    Full Text Available Many present spaceborne synthetic aperture radar (SAR systems are constrained to only two channels for ground moving target indication (GMTI. Along-track interferometry (ATI technique is currently exploited to detect slowly moving targets and measure their radial velocity and azimuth real position. In this paper, based on the joint probability density function (PDF of interferogram's phase and amplitude and the two hypotheses “clutter” and “clutter plus signal”, several constant false alarm rate (CFAR detection criteria are analyzed for their capabilities and limitations under low signal-to-clutter ratio (SCR and low clutter-to-noise ratio (CNR conditions. The CFAR detectors include one-step CFAR detector with interferometric phase, two-step CFAR detectors, and two-dimensional (2D CFAR detector. The likelihood ratio test (LRT based on the Neyman-Pearson (NP criterion is exploited as an upper bound for the performance of the other CFAR detectors. Performance analyses demonstrate the superiority of the 2D CFAR techniques to detect dim slowly moving targets for spaceborne system.

  5. High resolution orientation mapping of secondary phases in ATI 718Plus® alloy

    Directory of Open Access Journals (Sweden)

    Krakow Robert

    2014-01-01

    Full Text Available The polycrystalline superalloy ATI 718Plus ® (hereafter 718Plus has been developed to replace the established alloy Inconel 718 by offering higher temperature capability for applications in gas turbines. The alloy exhibits two secondary phases in the austenitic matrix; it is strengthened by the γ′-phase with η-phase discontinuously precipitated at the grain boundaries. It can be utilized to control grain growth during forging. Generally, hexagonal η phase has been reported to possess a defined crystallographic orientation with the matrix. However, the material studied here exhibits blocky η-phase that has been precipitated and grown during thermo-mechanical processing. Therefore a measurable change in orientation relationship is expected. The standard technique for orientation mapping is electron back-scattered diffraction with spatial resolution of 100 nm. That is insufficient for studying η-phase in 718Plus. By applying high resolution orientation mapping in the transmission electron microscope (Philips CM 300 FEGTEM equipped with a Nanomegas ASTARTM system a resolution of 3 nm was achieved. The indexed diffraction data was analysed using the Matlab Toolbox Mtex. The analysis included grain reconstruction and exclusion of low confidence measurements. The data set allows generating phase boundary maps indicating interfaces characteristics. Quantitative assessment shows that only 19% of the γ-η-interfaces fulfil the orientation relationship.

  6. 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

  7. 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

  8. The ATI score (age-thrombus burden-index of microcirculatory resistance) determined during primary percutaneous coronary intervention predicts final infarct size in patients with ST-elevation myocardial infarction: a cardiac magnetic resonance validation study.

    Science.gov (United States)

    De Maria, Giovanni Luigi; Alkhalil, Mohammad; Wolfrum, Mathias; Fahrni, Gregor; Borlotti, Alessandra; Gaughran, Lisa; Dawkins, Sam; Langrish, Jeremy P; Lucking, Andrew J; Choudhury, Robin P; Porto, Italo; Crea, Filippo; Dall'Armellina, Erica; Channon, Keith M; Kharbanda, Rajesh K; Banning, Adrian P

    2017-10-20

    The age-thrombus burden-index of microcirculatory resistance (ATI) score is a diagnostic tool able to predict suboptimal myocardial reperfusion before stenting, in patients with ST-elevation myocardial infarction (STEMI). We aimed to validate the ATI score against cardiac magnetic resonance imaging (cMRI). The ATI score was calculated prospectively in 80 STEMI patients. cMRI was performed within 48 hours in all patients and in 50 patients at six-month follow-up to assess the extent of infarct size (IS%) and microvascular obstruction (MVO%). The ATI score was calculated using age (>50=1 point), pre-stenting index of microcirculatory resistance (IMR) (>40 and <100=1 point; ≥100=2 points) and angiographic thrombus score (4=1 point; 5=3 points). ATI score was closely related to final IS% (ATI.

  9. Electron impact ionization of atomic hydrogen from the 1S and 2S states

    Energy Technology Data Exchange (ETDEWEB)

    Bartschat, K.; Bray, I.

    1996-05-01

    We present results from R-Matrix with Pseudo-States (RMPS) and Convergent Close-Coupling (CCC) calculations for electron impact total ionization of the 1S and 2S states of atomic hydrogen in the energy region from threshold to 100 eV. Particular attention is given to the near threshold region. We find the results for energies more than 2 eV above threshold to be in excellent agreement with the available experimental data. (authors). 19 refs., 3 figs.

  10. Ionization in elliptically polarized pulses: Multielectron polarization effects and asymmetry of photoelectron momentum distributions

    DEFF Research Database (Denmark)

    Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer

    2012-01-01

    In the tunneling regime we present a semiclassical model of above-threshold ionization with inclusion of the Stark shift of the initial state, the Coulomb potential, and a polarization induced dipole potential. The model is used for the investigation of the photoelectron momentum distributions...... in close to circularly polarized light, and it is validated by comparison with ab initio results and experiments. The momentum distributions are shown to be highly sensitive to the tunneling exit point, the Coulomb force, and the dipole potential from the induced dipole in the atomic core...

  11. Spin dynamics in relativistic ionization with highly charged ions in super-strong laser fields

    International Nuclear Information System (INIS)

    Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Müller, Carsten; Paulus, Gerhard G

    2014-01-01

    Spin dynamics and induced spin effects in above-threshold ionization of hydrogenlike highly charged ions in super-strong laser fields are investigated. Spin-resolved ionization rates in the tunnelling regime are calculated by employing two versions of a relativistic Coulomb-corrected strong-field approximation (SFA). An intuitive simpleman model is developed which explains the derived scaling laws for spin flip and spin asymmetry effects. The intuitive model as well as our ab initio numerical simulations support the analytical results for the spin effects obtained in the dressed SFA where the impact of the laser field on the electron spin evolution in the bound state is taken into account. In contrast, the standard SFA is shown to fail in reproducing spin effects in ionization even at a qualitative level. The anticipated spin-effects are expected to be measurable with modern laser techniques combined with an ion storage facility. (paper)

  12. Sondeo arqueológico en el yacimiento de Potorrosín VI (Oñati, Gipuzkoa.

    Directory of Open Access Journals (Sweden)

    Alvaro Arrizabalaga

    1992-01-01

    Full Text Available El yacimiento de Potorrosín VI se localiza en el valle del río Arantzazu (Oñati, Guipúzcoa. En el curso de un sondeo realizado durante 1987, y en algunas actuaciones anteriores, se ha localizado una secuencia estratigráfica que abarca varias fases de la prehistoria con cerámica y al menos una ocupación (Nivel IX correspondiente probablemente al Paleolítico superior final. En este artículo presentamos la estratigrafía y materiales obtenidos.

  13. Effect of heat input on heat affected zone cracking in laser welded ATI Allvac 718Plus superalloy

    International Nuclear Information System (INIS)

    Idowu, O.A.; Ojo, O.A.; Chaturvedi, M.C.

    2007-01-01

    The heat affected zones (HAZs) of low and high heat input laser welds of a newly developed superalloy, ATI Allvac 718Plus, were studied. Low heat input welds suffered significant HAZ grain boundary liquation cracking, while no cracking was observed in spite of a more extensive HAZ intergranular liquation in the higher heat input welds. Combination of lower welding stresses generated during cooling, and relaxation of these stresses by thick intergranular liquid were suggested to be the factors that contributed to the absence of cracking in the high heat input welds. Further, healing of some of the HAZ cracks in lower heat input welds by fusion zone interdendritic liquid occurred through liquid backfilling

  14. Agama Sebagai Kesadaran Ideologis: Refleksi Perubahan Sosial Ali Syari’ati

    Directory of Open Access Journals (Sweden)

    Imam Bonjol Jauhari

    2016-06-01

    Full Text Available Abstract: In the context of social change, the thought of Ali Syar'ati, if seen from the perspective of its frameworks and methods,is different from the thought of other Islamic movements.On the one hand, Shari'ati’s thought opposes the Iranian authority, Shah Pahlavi, but on the other hand, it is totally different from the traditional Iranian anti-change cleric, and it is also in contrast to the radical Islamic movements that do political rebellion against the ruler.Shari'atiput up political resistance through revolutionary ideas influencing public opinion to understand Islam as a doctrine which has an emancipatory interest, that is, the belief of Islam as a school of thought and action in the fight against social and economic injustice, despotic ruler, and the fetters of culture. Efforts to comprehend Islamic meanings in modern and contextual Islamic thought presents two patterns of social changes; first is the pattern of moderatemovement and second is extreme one. The formerleads more specifically to how to implement Islamic values in the national way of life, and   sense of nationalitywithout being trapped inreligious symbols and labels, while the latter leads totheimplementation of Islamic values and symbolismand labeling whichare both considered to be important. So the former tends to take more substantive values of Islam that is essentially concerned with the purpose of realization of the ideals of Islam, while the latter tends to the enactment of Islamic lawin all aspects of community life.  الملخص: في سياق التغيير الاجتماعي، يعتقد أن فكرة علي شريعتي لها إطار وأساليب تختلف عن أساليب رواد الفكر والحركات الإسلامية الأخرى. من ناحية ،أن شريعتي يكافح ضد سلطة مستبدة في إيران، شاه بهلوي. ومن ناحية أخرى، كان مختلفا تماما عن علماء الدين

  15. Quantum interference in laser-induced nonsequential double ionization

    Science.gov (United States)

    Quan, Wei; Hao, XiaoLei; Wang, YanLan; Chen, YongJu; Yu, ShaoGang; Xu, SongPo; Xiao, ZhiLei; Sun, RenPing; Lai, XuanYang; Hu, ShiLin; Liu, MingQing; Shu, Zheng; Wang, XiaoDong; Li, WeiDong; Becker, Wilhelm; Liu, XiaoJun; Chen, Jing

    2017-09-01

    Quantum interference plays an important role in various intense-laser-driven atomic phenomena, e.g., above-threshold ionization and high-order-harmonic generation, and provides a useful tool in ultrafast imaging of atomic and molecular structure and dynamics. However, it has eluded observation in nonsequential double ionization (NSDI), which serves as an ideal prototype to study electron-electron correlation. Thus far, NSDI usually could be well understood from a semiclassical perspective, where all quantum aspects have been ignored after the first electron has tunneled. Here we perform coincidence measurements for NSDI of xenon subject to laser pulses at 2400 nm. It is found that the intensity dependence of the asymmetry parameter between the yields in the second and fourth quadrants and those in the first and third quadrants of the electron-momentum-correlation distributions exhibits a peculiar fast oscillatory structure, which is beyond the scope of the semiclassical picture. Our theoretical analysis indicates that this oscillation can be attributed to interference between the contributions of different excited states in the recollision-excitation-with-subsequent-ionization channel. Our work demonstrates the significant role of quantum interference in NSDI and may create an additional pathway towards manipulation and imaging of the ultrafast atomic and molecular dynamics in intense laser fields.

  16. Microstructure and Mechanical Properties of Friction Stir Welded Dissimilar Titanium Alloys: TIMET-54M and ATI-425

    Directory of Open Access Journals (Sweden)

    Kapil Gangwar

    2016-10-01

    Full Text Available Weight reduction in automobiles and in aerospace industries can profoundly register for the behemoth change in the consumption of the fossil fuels and, in turn, CO2 emission. With a promising hope in hindsight for weight reduction, we have successfully produced butt joints of friction stir welded (FSWed dissimilar, and rather novice, α-β titanium alloys—ATI-425 and TIMET-54M. The study presented in this article encompasses the microstructural and mechanical properties of the joints for two cases, (1 ATI-425 on the advancing side; and (2 TIMET-54M on the advancing side. The evolution of microstructure and concomitant mechanical properties are characterized by optical microscopy, microhardness, and tensile properties. A detailed description of the microstructural evolution and its correlation with the mechanical properties have been presented in this study. Our investigations suggest that mixing patterns are dependent on the location (advancing, or retreating of the alloying sheet. However, the microstructure in the weld nugget (WN is quite similar (grain boundary α, and basket weave morphology consisting of α + β lamellae in both cases with traces of untransformed β. The thermo-mechanically affected zone (TMAZ on the either side of the weld is primarily affected by the microstructure of the base material (BM. A noticeable increase in the hardness values in the WN is accompanied by significant deflection on the advancing and retreating sides. The tensile properties extracted from the global stress strain curves are comparable with minimal difference for both cases. In both cases, the fracture occurred on the retreating side of the weld.

  17. 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)

  18. Acumulaciones detríticas cuaternarias en el valle del río Oñati (Guipúzcoa.

    Directory of Open Access Journals (Sweden)

    UGARTE, F.M.; GONZALEZ, J.A., ALONSO, F.

    1984-01-01

    Full Text Available Se ha definido un espacio centrado en una cuenca hidrográfica (cuenca del río Oñati: cabecera del río Deba, y sobre él se ha llevado a cabo una investigación intensiva de búsqueda, localización y análisis sedimentológico de depósitos detríticos Cuaternarios. Se han catalogado varias docenas de depósitos de todo tipo: coluviones, fluviales, periglaciares...; teniéndose sólamente en cuenta los depósitos superficiales, dejando de lado los que se hallan en el interior de las cuevas. El objetivo que se pretende es el de aportar información que pueda ser utilizada en un próximo futuro, para tratar de reconstruir la evolución morfogenética del Cuaternario en nuestra región.

  19. Ionization potentials of seaborgium

    International Nuclear Information System (INIS)

    Johnson, E.; Pershina, V.; Fricke, B.

    1999-01-01

    Multiconfiguration relativistic Dirac-Fock values were calculated for the first six ionization potentials of seaborgium and of the other group 6 elements. No experimental ionization potentials are available for seaborgium. Accurate experimental values are not available for all of the other ionization potentials. Ionic radii for the 4+ through 6+ ions of seaborgium are also presented. The ionization potentials and ionic radii obtained will be used to predict some physiochemical properties of seaborgium and its compounds

  20. 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

  1. Steplike intensity threshold behavior of extreme ionization in laser-driven xenon clusters.

    Science.gov (United States)

    Döppner, T; Müller, J P; Przystawik, A; Göde, S; Tiggesbäumker, J; Meiwes-Broer, K-H; Varin, C; Ramunno, L; Brabec, T; Fennel, T

    2010-07-30

    The generation of highly charged Xe(q+) ions up to q=24 is observed in Xe clusters embedded in helium nanodroplets and exposed to intense femtosecond laser pulses (λ=800  nm). Laser intensity resolved measurements show that the high-q ion generation starts at an unexpectedly low threshold intensity of about 10(14)  W/cm2. Above threshold, the Xe ion charge spectrum saturates quickly and changes only weakly for higher laser intensities. Good agreement between these observations and a molecular dynamics analysis allows us to identify the mechanisms responsible for the highly charged ion production and the surprising intensity threshold behavior of the ionization process.

  2. Ionizing radiations and cancer

    Directory of Open Access Journals (Sweden)

    Süleyman Daşdağ

    2010-06-01

    Full Text Available The aim of this study is to evaluate the biologic effects of ionizing radiation and relation between medical diagnosticradiation exposure and cancer risk. Many unnecessary ionizing radiation applications are performed in the medicalcenters and hospitals. Therefore the health staff and the patients expose to serious risks of radiation. On the other hand, recently some studies, which suggested relationshipsbetween low dose ionizing radiation and some cancers, have been published. The relationship between low dose ionizing radiation and cancer can be more understandablewhen the stochastic effects of ionizing radiationtake into consideration. This presented review calls attention to the fact that low dose ionizing radiation may be an important factor for increased cancer risk. Therefore,physicians, health workers and patients have to pay maximum attention to avoid hazards of low dose ionizing radiation.

  3. El Máster de Sociologìa Jurìdica de Oñati: la Percepción de los Graduados (The Oñati Master on Sociology of Law: the Alumnae’s Perception

    Directory of Open Access Journals (Sweden)

    Susana Arrese Murguzur

    2016-09-01

    Full Text Available The article is a contribution to the evaluation of the master program of the Oñati International Institute for the Sociology of Law in its 25th anniversary. It describes the geographical origin of the 289 graduates and reports their opinions regarding the program. In general, the alumnae describe as positive their academic experience as very positive. They appreciate acquiring a new vision of law and the suitable instruments for their analyses. They report that their studies have been useful for their current performance as professors, judges, civil servants or lawyers in their country of origin. They evaluate very positively the contacts with professors and staff, the institute’s services and the conviviality in the residence and in the town of Oñati. No negative opinions were received.Como contribución para un balance de los 25 años de vida del Instituto Internacional de Sociología Jurídica de Oñati, el artículo describe la procedencia geográfica de los 289 graduados que ha producido y reporta las opiniones de éstos. En general, los graduados consideran su experiencia académica como muy positiva apreciando haber adquirido una manera nueva de mirar al derecho e instrumentos adecuados para su análisis. Opinan que los estudios han sido útiles para sus tareas actuales en sus países de origen en donde se desempeñan como profesores, jueces, funcionarios o abogados. Consideran muy positivamente la relación que tuvieron con los profesores y el personal del instituto, los servicios que éste ofrece y la convivialidad tanto en la residencia como en el pueblo de Oñati. No se recibieron opiniones negativas.DOWNLOAD THIS PAPER FROM SSRN: http://ssrn.com/abstract=2676532

  4. Conceptions Of Freedom In The Use Of The Open Public Space: The Foruen Enparantza In Oñati As An Illustration

    Directory of Open Access Journals (Sweden)

    Leopoldo Cruz Balbuena

    2017-12-01

    Full Text Available Freedom is a mantle that covers all aspects of existence. Just as on a cold winter night, its absence is noticeable. But not only in the absolute absence of freedom must we think of it. Neither should we think of freedom in binary terms (there is or is not. Freedom is much more than a concept, we live, enjoy, exhaust, and suffer. Freedom carries responsibility in the realm of the inner and especially in the public realm. This work suggests the study of freedom in the realm of the public and seeks to link it with the place where freedom is exercised. And being the public freedom the object of study of this work, I will review the great minds that studied it before, the norms that regulate it and the perception of the individuals that live in the town of Oñati. This dissertation unveils the amount, size, colour, and texture of the Oñati idea of freedom.La libertad es un manto que cubre todos los aspectos de la existencia. Sólo en una fría noche de invierno, su ausencia se hace presente. Pero, no sólo en la ausencia absoluta de libertad debemos pensar en ella. Tampoco debemos pensar en ella en términos binarios (existe o no. La libertad es mucho más que un concepto, la vivimos, disfrutamos, agotamos y sufrimos. La libertad tiene aparejada la responsabilidad, en el reino de lo interno y especialmente en el reino de lo público. Este trabajo sugiere el estudio de la libertad en el reino de lo público y busca vincularla con el lugar en que es ejercida. Y, siendo la libertad pública el objeto de estudio de este trabajo, repasaré las grandes mentes que la han estudiado en el pasado, las normas que la regulan y la percepción de los individuos que viven en el pueblo de Oñati. Esta tesina revela la cantidad, tamaño, color y textura de la idea de libertad en Oñati. DOWNLOAD THIS PAPER FROM SSRN: http://ssrn.com/abstract=3064765

  5. Apa l’Etrusco sbarca a Roma e passa il testimone ad Ati. Un cortometraggio tridimensionale per raccontare il santuario di Portonaccio a Veio

    Directory of Open Access Journals (Sweden)

    Alfonsina Russo

    2015-08-01

    Full Text Available Computer graphics movies are a favourite media for edutainment. The 3D stereoscopic short movie “Ati at the discovery of Veii” is an interesting example of philologically accurate reconstructions coupled with a communication aimed at a wide audience.  Developed by Cineca for a joint project involving the National Etruscan Museum of Villa Giulia and Genus Bononiae – Museum of the History of Bologna, the movie is grounded on the software Blender and a strong open source commitment.

  6. 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

  7. 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

  8. 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

  9. 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)

  10. 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

  11. 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.)

  12. 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.

  13. Kelvin spray ionization.

    Science.gov (United States)

    Özdemir, Abdil; Lin, Jung-Lee; Gillig, Kent J; Chen, Chung-Hsuan

    2013-11-21

    A novel self-powered dual spray ionization source has been developed for applications in mass spectrometry. This new source does not use any power supply and produces both positive and negative ions simultaneously. The idea behind this ionization source comes from the Kelvin water dropper. The source employs one or two syringes, two pneumatic sprays operated over a range of flow rates (0.15-15 μL min(-1)) and gas pressures (0-150 psi), and two double layered metal screens for ion formation. A variable electrostatic potential from 0 to 4 kV can be produced depending on solvent and gas flow rates that allow gentle ionization of compounds. There are several parameters that affect the performance during ionization of molecules including the flow rate of solvent, gas pressure, solvent acidity, position of spray and metal screens with respect to each other and distance between metal screens and the counter electrode. This ionization method has been successfully applied to solutions of peptides, proteins and non-covalent complexes. In comparison with ESI, the charge number of the most populated state is lower than that from ESI. It indicates that this is a softer ionization technique and it produces more protein ions with folded structures. The unique features of Kelvin spray ionization (KeSI) are that the method is self-powered and ionization occurs at very low potentials by providing very low internal energy to the ions. This advantage can be used for the ionization of very fragile molecules and investigation of non-covalent interactions.

  14. 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

  15. 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

  16. Directed Field Ionization

    Science.gov (United States)

    Gregoric, Vincent C.; Kang, Xinyue; Liu, Zhimin Cheryl; Rowley, Zoe A.; Carroll, Thomas J.; Noel, Michael W.

    2017-04-01

    Selective field ionization is an important experimental technique used to study the state distribution of Rydberg atoms. This is achieved by applying a steadily increasing electric field, which successively ionizes more tightly bound states. An atom prepared in an energy eigenstate encounters many avoided Stark level crossings on the way to ionization. As it traverses these avoided crossings, its amplitude is split among multiple different states, spreading out the time resolved electron ionization signal. By perturbing the electric field ramp, we can change how the atoms traverse the avoided crossings, and thus alter the shape of the ionization signal. We have used a genetic algorithm to evolve these perturbations in real time in order to arrive at a target ionization signal shape. This process is robust to large fluctuations in experimental conditions. This work was supported by the National Science Foundation under Grants No. 1607335 and No. 1607377 and used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number OCI-1053575.

  17. Above-threshold structure in {sup 244}Cm neutron-induced fission cross section

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V.M. [Radiation Physics and Chemistry Problems Inst., Minsk-Sosny (Belarus)

    1997-03-01

    The quasi-resonance structure appearing above the fission threshold in neutron-induced fission cross section of {sup 244}Cm(n,f) is interpreted. It is shown to be due to excitation of few-quasiparticle states in fissioning {sup 245}Cm and residual {sup 244}Cm nuclides. The estimate of quasiparticle excitation thresholds in fissioning nuclide {sup 245}Cm is consistent with pairing gap and fission barrier parameters. (author)

  18. Channel-closing effects in strong-field ionization by a bicircular field

    Science.gov (United States)

    Milošević, D. B.; Becker, W.

    2018-03-01

    Channel-closing effects, such as threshold anomalies and resonantlike intensity-dependent enhancements in strong-field ionization by a bicircular laser field are analyzed. A bicircular field consists of two coplanar corotating or counter-rotating circularly polarized fields having different frequencies. For the total detachment rate of a negative ion by a bicircular field we observe threshold anomalies and explain them using the Wigner threshold law and energy and angular momentum conservation. For the corotating bicircular case, these effects are negligible, while for the counter-rotating case they are pronounced and their position depends on the magnetic quantum number of the initial state. For high-order above-threshold ionization of rare-gas atoms by a counter-rotating bicircular laser field we observe very pronounced intensity-dependent enhancements. We find all four types of threshold anomalies known from collision theory. Contrary to the case of linear polarization, channel-closing effects for a bicircular field are visible also in the cutoff region of the electron energy spectrum, which is explained using quantum-orbit theory.

  19. Photoelectron interference fringes by super intense x-ray laser pulses

    International Nuclear Information System (INIS)

    Toyota, Koudai; Morishita, Toru; Watanabe, Shinichi; Tolstikhin, Oleg I

    2009-01-01

    The photoelectron spectra of H - produced by circularly polarized strong high-frequency laser pulses are theoretically studied. An oscillating substructure in the above-threshold ionization (ATI) peaks is observed, which extends the validity of the earlier findings in the 1D calculations [K. Toyota et al., Phys. Rev. A 76, 043418 (2007)] and 3D calculations for linear polarization [O. I. Tolstikhin, Phys. Rev. A 77, 032712 (2008)]. Its origin is due to an interference between a pair of photoelectron wave packets created in the rising and falling part of the pulse, which appears clearly in the stabilization regime.

  20. 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)

  1. Surface ionization theory

    International Nuclear Information System (INIS)

    Bonnal, J.-F.; Pelissier, Andre

    1974-01-01

    After a brief theoretical review, the relationship existing between the ionization rate in the vicinity of a metallic plate in thermodynamic equilibrium with a cesium plasma and the density of electron current issued from the same plate is presented. The evolution of this density of current is represented by the Langmuir S-curves. It is shown that knowledge of the S-curves leads to that of the critical temperatures and of the ionization rates when the generated ions are extracted by an electric field. The influence of the principal parameters (the nature and temperature of the plate and the cesium flow supplying it) is analyzed using the Rasor theory. The theoretical results obtained using a model of the flat plate represent fairly closely the operations observed experimentally on porous tungstem ionizers [fr

  2. 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.)

  3. 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.)

  4. 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.

  5. 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

  6. Ionizing radiation in hospitals

    International Nuclear Information System (INIS)

    This booklet is concerned with radiation safety of radiologist and other hospital personnel. Part 1 deals with properties of radiation in general (especially of ionizing radiation). In part 2, different applications of radiation in hospitals are discussed. Part 3 indicates what to do to make improvements to not totally safe situations in hospitals. (Auth./G.J.P.)

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.)

  12. The Effect of Boron and Zirconium on Microstructure and Stress-Rupture Life of Nickel-based Superalloy ATI 718Plus

    Directory of Open Access Journals (Sweden)

    Seyed Ali Hosseini

    2015-12-01

    Full Text Available The effects of boron and zirconium on the microstructure, hardness and stressrupture life of the nickel-based superalloy ATI 718Plus were investigated in this study. Four alloys with different percentages of boron (0.005-0.01 wt.% and zirconium (0-0.1 wt% were cast through a vacuum induction melting furnace and then were rolled. The microstructural studies indicated an increased percentage of δ phase, carbide precipitates and twins in the presence of zirconium. The percentage of carbide (boron carbide precipitates was increased and the solidification range of the alloy was decreased in the presence of boron in the composition. Furthermore, the results obtained from the hardness and stress-rupture tests showed the significant role of both elements in increasing hardness and improved rupture life of the alloy. The maximum rupture life was observed in the alloy which contained the highest percentages of boron and zirconium in its composition. This can be attributed mainly to the increased percentage of δ phase on grain boundaries and their enhanced high-temperature strength.

  13. 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.)

  14. Ionizing radiation and neoplasia

    International Nuclear Information System (INIS)

    Fajardo, L.F.

    1986-01-01

    Among the well accepted causes of neoplasia, ionizing radiation is quite prominent. Its oncogenic role was suspected by a few pioneers in the field of radiation biology, and some evidence for its oncogenicity has been available for almost 80 years. Since then unquestionable and abundant proof, statistical and experimental, has linked radiation with multiple tumors in mammals. Other forms of radiation (e.g., ultraviolet) are also causally related to neoplasia. This review, however, refers only to the tumors associated with ionizing radiation, either electromagnetic (i.e., gamma and x-rays) or particulate (alpha particles, neutrons, etc.). The field of radiation oncogenesis can be compared to a sea of hypotheses, with a few solid islands of facts. This paper considers the facts (specific radiation-induced neoplasms, risk data, etc.) and then considers some of the hypotheses (possible mechanisms of radiation oncogenesis)

  15. Ionization by nuclear transitions

    International Nuclear Information System (INIS)

    Freedman, M.S.

    1975-01-01

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

  16. 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

  17. 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)

  18. 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

  19. Ionization cross section of partially ionized hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Baimbetov, F B; Kudyshev, Z A [Department of Physics, al - Farabi Kazakh National University, Almaty (Kazakhstan)], E-mail: Bfb77@kazsu.kz, E-mail: Z.Kudyshev@mail.ru

    2008-05-01

    In present work the electron impact ionization cross section is considered. The electron impact ionization cross section is calculated, based on pseudopotential model of interaction between plasma particles which accounts correlation effects. It is calculated with help of two methods: classical and quantum - mechanical (Born approximation). The ionization cross section is compared with corresponding results of other authors and experimental data. It has been shown that it is very important to take into account an influence of the surrounding during consideration of ionization processes.

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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)

  9. [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.

  10. 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.

  11. 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

  12. Multiphoton ionization of Uracil

    Science.gov (United States)

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

    2016-05-01

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

  13. On the Saha Ionization Equation

    Indian Academy of Sciences (India)

    On the Saha Ionization Equation. Sushanta Dattagupta. General Article Volume 23 Issue 1 January 2018 pp 41-55. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/023/01/0041-0055. Keywords. Ionization, astrophysics, spectroscopy, chemical reaction, transition state. Abstract.

  14. 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

  15. 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

  16. Ionization Mechanism of Matrix-Assisted Laser Desorption/Ionization

    Science.gov (United States)

    Lu, I.-Chung; Lee, Chuping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2015-07-01

    In past studies, mistakes in determining the ionization mechanism in matrix-assisted laser desorption/ionization (MALDI) were made because an inappropriate ion-to-neutral ratio was used. The ion-to-neutral ratio of the analyte differs substantially from that of the matrix in MALDI. However, these ratios were not carefully distinguished in previous studies. We begin by describing the properties of ion-to-neutral ratios and reviews early experimental measurements. A discussion of the errors committed in previous theoretical studies and a comparison of recent experimental measurements follow. We then describe a thermal proton transfer model and demonstrate how the model appropriately describes ion-to-neutral ratios and the total ion intensity. Arguments raised to challenge thermal ionization are then discussed. We demonstrate how none of the arguments are valid before concluding that thermal proton transfer must play a crucial role in the ionization process of MALDI.

  17. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to Saccharomyces boulardii ATY-SB-101 (BCCM/MUCL 53837) (ID 1010, 1011, further assessment) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on health claims pursuant to Article 13.1 of Regulation (EC) No 1924/2006 in the framework of further assessment related to Saccharomyces boulardii ATY......-SB-101 and the following claimed effects: "maintains and restores the natural flora" and "modulating both innate and adaptive host immunity to respond against pathogen infection". The food constituent that is the subject of the claims, Saccharomyces boulardii ATY-SB-101 (BCCM/MUCL 53837...

  18. 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.

  19. Pulsed helium ionization detection system

    Science.gov (United States)

    Ramsey, R.S.; Todd, R.A.

    1985-04-09

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  20. 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

  1. 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

  2. Effects of ionizing radiation

    International Nuclear Information System (INIS)

    Tadmor, J.

    1984-05-01

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

  3. 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...

  4. 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...

  5. Resonance ionization for analytical spectroscopy

    Science.gov (United States)

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

    1976-01-01

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

  6. CERI: Ionizing Radiation Calibration Centre

    International Nuclear Information System (INIS)

    Bouteiller, E.

    1979-01-01

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

  7. Ionizing radiation and cancer prevention.

    OpenAIRE

    Hoel, D G

    1995-01-01

    Ionizing radiation long has been recognized as a cause of cancer. Among environmental cancer risks, radiation is 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...

  8. Resonance ionization scheme development for europium

    CERN Document Server

    Chrysalidis, K; Fedosseev, V N; Marsh, B A; Naubereit, P; Rothe, S; Seiffert, C; Kron, T; Wendt, K

    2017-01-01

    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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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)

  15. 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

  16. 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

  17. Ionization detectors in environmental analysis

    International Nuclear Information System (INIS)

    Leonhardt, J.W.

    1982-01-01

    Ionization detectors (IDs) use the information contained in the radiation-produced ionization current regarding the chemical composition of gas mixtures. The radionuclide radiation sources, 3 H, 55 Fe, 63 Ni, 85 Kr, 90 Sr, 241 Am, are used to produce carriers. Using recombination effects and carrier multiplication by electrical fields the response of IDs can be improved. There are electron capture detectors, cross-section detectors and noble-gas detectors, mainly used in gas chromatographic devices, and continuously working aerosol ionization detectors. Halocarbons, metal chelates, metal organic and inorganic compounds, pesticides, herbicides, insecticides, but also SO 2 , AsH 3 , ClCN, HCN, HF, NH 3 , CO, CO 2 , H 2 O, can be determined within the pp10 9 range. They are used in automatic systems to control air pollution around industrial plants, in hospitals and factories, but also to prevent high levels of pesticides in agriculture products. (author)

  18. 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.)

  19. The dosimetry of ionizing radiation

    CERN Document Server

    Bjaerngard, Bengt E; Kase, Kenneth R

    1987-01-01

    The Dosimetry of Ionizing Radiation, Volume II, attempts to fill the need for updated reference material on the field of radiation dosimetry. This book presents some broad topics in dosimetry and a variety of radiation dosimetry instrumentation and its application. The book opens with a chapter that extends and applies the concepts of microdosimetry to biological systems. This is followed by separate chapters on the state- of-the-art equipment and techniques used to determine neutron spectra; studies to determine recombination effects in ionization chambers exposed to high-intensity pulsed ra

  20. 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...

  1. 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

  2. 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)

  3. 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.

  4. 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.)

  5. 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

  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. 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

  8. 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 ...

  9. 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...

  10. 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

  11. CALCULATION OF IONIZATION RATE COEFFICIENTS OF ...

    African Journals Online (AJOL)

    We use a simple numerical method to generate the ionization rates starting from the cross sections. These last are obtained by code FAC (Flexible Atomic Code). Our computation results will be compared with those published. Key words: Atomic data, radiative collisional Models, Ionization rate, cross Sections of ionization.

  12. 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)

  13. 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...

  14. 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.)

  15. Position-sensitive ionization detectors for ionizing beams diagnostics

    CERN Document Server

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

    2002-01-01

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

  16. 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

  17. 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

  18. LONGITUDINAL IONIZATION COOLING WITHOUT WEDGES

    International Nuclear Information System (INIS)

    BERG, J.S.

    2001-01-01

    The emittance of a muon beam must be reduced very rapidly due to the finite lifetime of the muons. The most effective known way to accomplish this is ionization cooling. It is straightforward to reduce transverse emittance through ionization cooling, but the reducing the longitudinal emittance is more challenging. Longitudinal cooling is necessary for a muon collider, and would be helpful for a neutrino factory. The method traditionally proposed for longitudinal cooling is emittance exchange involving wedges of absorber material: the longitudinal emittance is reduced at the cost of increased transverse emittance. The larger transverse emittance can then be reduced straightforwardly. An alternative method is proposed here, which does not require wedges of material but instead makes slight modifications to the standard transverse cooling lattice. We demonstrate a lattice which is a slight modification to a standard Super FOFO transverse cooling lattice, which has linear eigenvalues all of which have magnitude less than one

  19. Ionization potentials some variations, implications and applications

    CERN Document Server

    Ahrens, L H

    1983-01-01

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

  20. 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

  1. 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.

  2. 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)

  3. Ionization-based detectors for gas chromatography.

    Science.gov (United States)

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. 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.)

  5. 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

  6. 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.

  7. 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.

  8. 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...... 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...

  9. 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.

  10. Elastic properties of perovskite ATiO{sub 3} (A = Be, Mg, Ca, Sr, and Ba) and PbBO{sub 3} (B = Ti, Zr, and Hf): First principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pandech, Narasak; Limpijumnong, Sukit, E-mail: sukit@sut.ac.th [School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Synchrotron Light Research Institute, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400 (Thailand); Sarasamak, Kanoknan [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

    2015-05-07

    The mechanical properties of perovskite oxides depend on two metal oxide lattices that are intercalated. This provides an opportunity for separate tuning of hardness, Poisson's ratio (transverse expansion in response to the compression), and shear strength. The elastic constants of series of perovskite oxides were studied by first principles approach. Both A-site and B-site cations were systematically varied in order to see their effects on the elastic parameters. To study the effects of A-site cations, we studied the elastic properties of perovskite ATiO{sub 3} for A being Be, Mg, Ca, Sr, or Ba, one at a time. Similarly, for B-site cations, we studied the elastic properties of PbBO{sub 3} for B being Ti, Zr, or Hf, one at a time. The density functional first principles calculations with local density approximation (LDA) and generalized gradient approximation (GGA) were employed. It is found that the maximum C{sub 11} elastic constant is achieved when the atomic size of the cations at A-site and B-site are comparable. We also found that C{sub 12} elastic constant is sensitive to B-site cations while C{sub 44} elastic constant is more sensitive to A-site cations. Details and explanations for such dependencies are discussed.

  11. Elastic properties of perovskite ATiO3 (A = Be, Mg, Ca, Sr, and Ba) and PbBO3 (B = Ti, Zr, and Hf): First principles calculations

    International Nuclear Information System (INIS)

    Pandech, Narasak; Limpijumnong, Sukit; Sarasamak, Kanoknan

    2015-01-01

    The mechanical properties of perovskite oxides depend on two metal oxide lattices that are intercalated. This provides an opportunity for separate tuning of hardness, Poisson's ratio (transverse expansion in response to the compression), and shear strength. The elastic constants of series of perovskite oxides were studied by first principles approach. Both A-site and B-site cations were systematically varied in order to see their effects on the elastic parameters. To study the effects of A-site cations, we studied the elastic properties of perovskite ATiO 3 for A being Be, Mg, Ca, Sr, or Ba, one at a time. Similarly, for B-site cations, we studied the elastic properties of PbBO 3 for B being Ti, Zr, or Hf, one at a time. The density functional first principles calculations with local density approximation (LDA) and generalized gradient approximation (GGA) were employed. It is found that the maximum C 11 elastic constant is achieved when the atomic size of the cations at A-site and B-site are comparable. We also found that C 12 elastic constant is sensitive to B-site cations while C 44 elastic constant is more sensitive to A-site cations. Details and explanations for such dependencies are discussed

  12. Atmospheric sampling glow discharge ionization source

    Science.gov (United States)

    McLuckey, S.A.; Glish, G.L.

    1989-07-18

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.

  13. [Plasma ionized magnesium concentration following cardiopulmonary bypass].

    Science.gov (United States)

    Amaya, Fumimasa; Fukui, Michihiko; Tsuruta, Hiroshi; Kooguchi, Kunihiko; Shimosato, Goshun

    2002-06-01

    We performed a retrospective study to analyze plasma ionized magnesium concentration following cardiopulmonary bypass. Severe decrease of ionized magnesium concentration associated with frequent abnormal ECG sign was found in a patient with magnesium-free cardioplegia. Cardioplegia containing 16 mmol.l-1 of magnesium ion maintained ionized magnesium concentration within normal ranges without postoperative magnesium loading. Use of cardioplegia containing magnesium or adequate magnesium supplement is thought to be essential for patients receiving cardiopulmonary bypass.

  14. 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)

  15. 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)

  16. 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.

  17. 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

  18. 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

  19. 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.)

  20. 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.

  1. 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)

  2. Ionization cross section for a strongly coupled partially ionized hydrogen plasma: variable phase approach

    Energy Technology Data Exchange (ETDEWEB)

    Baimbetov, F B; Kudyshev, Z A [Department of Physics, Al-Farabi Kazakh National University, 050012 Almaty (Kazakhstan)], E-mail: Fazylhan.Baimbetov@kaznu.kz, E-mail: Z.Kudyshev@mail.ru

    2009-05-29

    In the present work an electron impact ionization cross section is considered. The electron impact ionization cross section is calculated with the help of a variable phase approach to potential scattering. The Calogero equation is numerically solved, based on a pseudopotential model of interaction between partially ionized plasma particles, which accounts for correlation effects. As a result, scattering phase shifts are obtained. On the basis of the scattering phase shifts, the ionization cross section is calculated.

  3. 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

  4. 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)

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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.

  12. Ionization tube simmer current circuit

    Science.gov (United States)

    Steinkraus, R.F. Jr.

    1994-12-13

    A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current. 6 figures.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. METAL CHELATING AGENTS IV: ELECTRON IONIZATION AND ...

    African Journals Online (AJOL)

    The electron ionization (EI) and ammonia chemical ionization [CI (NH3)] mass spectral studies on 2-phenyl acetophenone semicarbazone are reported. The El spectrum shows a clearly identifiable molecular ion peak of weak intensity at m/z 253 and the base peak is observed at m/z 77. The CI (NH3) spectrum is ...

  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....

  20. 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

  1. 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

  2. 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...

  3. Ionization of atoms by bare ion projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Tribedi, L.C. [J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604 (United States)

    1997-02-01

    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} {ital 1997 American Institute of Physics.}

  4. 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.)

  5. How periodic orbit bifurcations drive multiphoton ionization

    Energy Technology Data Exchange (ETDEWEB)

    Huang, S [Center for Nonlinear Science, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430 (United States); Chandre, C [Centre de Physique Theorique, CNRS Luminy, Case 907, 13288 Marseille cedex 09 (France); Uzer, T [Center for Nonlinear Science, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430 (United States)

    2007-06-14

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

  6. Re-ionization and decaying dark matter

    Science.gov (United States)

    Dodelson, Scott; Jubas, Jay M.

    1991-01-01

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

  7. Carbon tetrafluoride + carbon in ionizing radiation

    International Nuclear Information System (INIS)

    Rodgers, B.R.; Reed, T.M.

    1977-01-01

    The apparent inertness of pure CF 4 in ionizing radiation disappears when CF 4 is mixed with other substances which can react with fluorine atoms, radicals, and ions produced by radiolysis. Studies of the time dependence of the composition of CF 4 + C mixtures in ionizing radiation show that both the amounts and maximum size of volatile perfluoralkanes larger than CF 4 increase with exposure in the ionizing radiation of a nuclear reactor. The ratio of material not volatile at 25 0 C increases and the ratio of CF 4 remaining decreases with exposure

  8. 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)

  9. Compositions curable with ionizing radiations

    International Nuclear Information System (INIS)

    Yamamichi, K.; Kodama, Takashi.

    1970-01-01

    Organic peroxides generally accelerate the curing reaction of radiation-curable resin compositions but, simultaneously, reduce the shelf life of the composition. Here is provided a new resin composition curable with ionizing radiations which is a solution of unsaturated alkyd resin, dially phthalate prepolymer, 1,2-polybutadiene or mixture thereof in a vinyl monomer containing hexachloroethane in place of an organic peroxide, the hexachloroethane accelerating the radiation curing without reducing the shelf life. The composition is composed of 100 parts of the resin, 20 to 80 parts of the vinyl monomer and 1 to 20 parts of hexachloroethane, and is useful for surface coatings, castings and impregnations. In one example, a solution of 100 parts of dially phthalate prepolymer (IV 58, AV 1.8, viscosity of 50% solution in MEK 80 cp) in 60 parts of vinyl acetate containing a varied quantity of hexachloroethane was exposed to Co 60 gamma rays (1.5x10 4 rad/hr) for 14 hours. The content of hexachloroethane (%) in the starting composition and the gel fraction (%) after cure were, respectively: 0, 29.3; 1, 44.6; 3, 72.0; 5, 84.5; 10, 96.1; 5 (CCl 4 in place of hexachloroethane), 37.2. (S. Kaichi)

  10. 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)

  11. 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

  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. 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.

  14. 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)

  15. Pulse valve with gas preliminary ionization

    International Nuclear Information System (INIS)

    Voronin, A.V.; Goncharov, S.E.; Danilov, A.D.; Kil'keev, R.Sh.; Kuznetsov, V.M.

    1984-01-01

    A pulse electrodynamic valve for the injection of weakly ionized gas into vacuum has been described. Gas ionization is realized in an intermediate chamber, located in electric field antinode in a waveguide cavity, in which a standing wave is excited. Total number of particles injected can be gradually varied in the range 10 14 -10 20 , at that, the number of charged particles varies from 10 10 to 10 11 . The valve time response constitutes approximately 400 μs. The valve is used to in ect the preliminarily ionized plasma into the ''Tornado'' magnetic trap. With its help in the volUme of 256 l a preliminarily ionized hydrogen plasma with the charged particle concentration 10 5 -10 6 cm -3 has been produced

  16. 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...

  17. 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)

  18. Theory of electron transfer and ionization

    International Nuclear Information System (INIS)

    Becker, R.L.

    1979-01-01

    The main effort reported is directed toward charge transfer and ionization in high energy atomic collisions. The research may be divided into classical trajectory calculations, quantum - mechanical collision theory, and phenomenological treatments of quantal interference effects in heavy ion collisions

  19. Atomica ionization by strong coherent radiation

    International Nuclear Information System (INIS)

    Brandi, H.S.; Davidovich, L.

    1979-07-01

    The relation among the three most frequently used non-perturbative methods proposed to study the ionization of atoms by strong electromagnetic fields is established. Their range of validity is also determined. (Author) [pt

  20. 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

  1. 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)

  2. 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)

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

    International Nuclear Information System (INIS)

    Burdin, Sergey; Horbatsch, Marko; Taylor, Wendy

    2012-01-01

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

  4. 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)

  5. 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....

  6. 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

  7. 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

  8. Ionization radiation curable polyacrylate resin coatings

    International Nuclear Information System (INIS)

    Miller, L.S.

    1975-01-01

    A carboxylic acid chloride or bromide, a sulfonyl chloride or bromide, cyanuric chloride, calcium hypochlorite or phosphorus oxychloride and optionally a buffering pigment are combined with a liquid, acrylate ester resin curable by exposure to high-energy ionizing radiation to yield a coating composition which upon being cured in air by exposure to ionizing radition yields a coating having an essentially tack-free surface. (Patent Office Record)

  9. Ametryne degradation by ionizing radiation

    International Nuclear Information System (INIS)

    Andrade, Debora Cristina de; Mori, Manoel Nunes; Duarte, Celina Lopes; Melo, Rita Paiva

    2007-01-01

    Ametryne may be released to the environment during its manufacture, transport, storage, formulation and use as selective herbicide for the control of annual broadleaf and grass weeds. It is applied as an aqueous suspension for preemergence or post-directed applications on crops. Depending on the pesticide formulation and type of application, ametryne residues may be detectable in water, soil and on the surfaces for months or years. The herbicide used to this study was Ametryne (commercial name, Gesapax 500), commonly used on field crops and on corn and commercialized since 1975. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.9871. In addition, the relative standard deviation was lower than 10%. The radiation-processing yield was evaluated by the destruction G-value (Gd) (Eq. 1), that is defined by the number of destroyed molecules by absorption of 100 eV of energy from ionizing radiation. Different concentrations of the herbicide (11.4 mol L -1 ; 22.7 mol L -1 ; 34.1 mol L -1 and 45.5 mol L -1 ) were irradiated at the AECL 'Gammacell 220' 60 Co source, with 1 kGy, 3 kGy, 6 kGy, 9 kGy, 12 kGy, 15 kGy and 30 kGy absorbed doses. After irradiation processing, the ametryne highest reduction rate occurs at low doses of radiation: at 6 kGy more than 85-90% of all ametryne compounds were removed. Two products of incomplete degradation of ametryne were identified as s-triazyne isomers. However, further work is needed in order to fully understand the ametryne degradation mechanisms the degradation yield of ametryne depends on its initial concentration and the process seems to be more efficient at higher concentrations. (author)

  10. 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.)

  11. 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)

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Analytic quantum-interference conditions in Coulomb corrected photoelectron holography

    Science.gov (United States)

    Maxwell, A. S.; Al-Jawahiry, A.; Lai, X. Y.; Figueira de Morisson Faria, C.

    2018-02-01

    We provide approximate analytic expressions for above-threshold ionization (ATI) transition probabilities and photoelectron angular distributions. These analytic expressions are more general than those existing in the literature and include the residual binding potential in the electron continuum propagation. They successfully reproduce the ATI side lobes and specific holographic structures such as the near-threshold fan-shaped pattern and the spider-like structure that extends up to relatively high photoelectron energies. We compare such expressions with the Coulomb quantum orbit strong-field approximation (CQSFA) and the full solution of the time-dependent Schrödinger equation for different driving-field frequencies and intensities, and provide an in-depth analysis of the physical mechanisms behind specific holographic structures. Our results shed additional light on what aspects of the CQSFA must be prioritized in order to obtain the key holographic features, and highlight the importance of forward scattered trajectories. Furthermore, we find that the holographic patterns change considerably for different field parameters, even if the Keldysh parameter is kept roughly the same.

  19. Resonant laser ionization of radioactive atoms

    CERN Document Server

    Köster, U; Mishin, V I

    2003-01-01

    Intense radioactive ion beams are produced by the isotope separation on-line method. The resonance ionization laser ion source (RILIS) can provide the chemical selectivity to separate beams with reduced isobaric contamination. The hot cavity RILIS at ISOLDE (CERN) uses copper vapor laser pumped dye lasers for the resonant transitions. Up to now 22 elements have been ionized with efficiencies of the order of 10%. Additional elements have been ionized with similar RILIS set- ups at the Institute of Spectroscopy (Troitsk), IRIS (Gatchina), Mainz University and TIARA (Takasaki). Ideas are discussed for future developments of this type of RILIS, which could further improve the efficiency, selectivity, rapidity of release and stability of the operation. The RILIS can also be applied for atomic spectroscopy studies of exotic radioactive isotopes, which are produced at rates of few atoms per second only. An interesting parallel is shown to the atomic vapor laser isotope separation (AVLIS), a large-scale application o...

  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. 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

  2. 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)

  3. 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.

  4. 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

  5. Fragmentation pathways of ethylene after core ionization

    Science.gov (United States)

    Gaire, B.; Bocharova, I.; Sturm, F. P.; Gehrken, N.; Haxton, D. J.; Belkacem, A.; Weber, Th.; Zohrabi, M.; Ben-Itzhak, I.; Gatton, A.; Williams, J.; Reedy, D.; Nook, C.; Landers, A.; Gassert, H.; Zeller, S.; Voigtsberger, J.; Jahnke, T.; Doerner, R.

    2014-05-01

    We have measured the Auger electrons in coincidence with the recoil ions, resulting from the core ionization of ethylene molecules, by employing the COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) method. The Auger-electron and recoil-ion energy maps are used to identify the fragmentation pathways and they are compared to the valence photo-double-ionization of ethylene. The dicationic electronic states favored by the propensity rules are identified and their role on the fragmentation pathways is discussed. The molecular-frame Auger electron angular distribution provides further insight into the breakup of this molecule after core ionization. Supported by the Director, Office of Science, Office of Basic Energy Sciences, and by the Division of Chemical Sciences, Geosciences, and Biosciences of the U.S. Department of Energy at LBNL under Contract No. DE-AC02-05CH11231.

  6. Ionized cluster beam technology for material science

    International Nuclear Information System (INIS)

    Takagi, Toshinori

    1997-01-01

    The most suitable kinetic energy range of ionized materials in film formation and epitaxial growth is from a few eV to a few hundreds eV, especially, less than about 100eV, when ions are used as a host. The main roles of ions in film formation are the effects due to their kinetic energy and the electronic charge effects which involve the effect to active film formation and the effect acceleration of chemical reactions. Therefore, it is important to develope the technology to transport large volume of a flux of ionized particles with an extremely low incident energy without any troubles due to the space charge effects and charge up problems on the surface. This is the exact motivation for us to have been developing the Ionized Cluster Beam (ICB) technology since 1972. By ICB technology materials (actually wide varieties of materials such as metal, semiconductor, magnetic material, insulator, organic material, etc.) are vaporized and ejected through a small hole nozzle into a high vacuum, where the vaporized material condenses into clusters with loosely coupled atoms with the sizes about from 100 to a few 1000 atoms (mainly 100-2000 atoms) by supercondensation phenomena due to the adiabatic expansion in this evaporation process through a small hole nozzle. In the ICB technology an atom in each cluster is ionized by irradiated by electron shower, and the ionized clusters are accelerated by electric field onto a substrate. The ionized clusters with neutral clusters impinged onto a substrate are spreaded separately into atoms migrating over the substrate, so that the surface migration energy of the impinged atoms, that is, surface diffusion energy are controlled by an incident energy of a cluster. In this report the theoretical and also experimental results of ICB technology are summarized

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 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

  13. Ionizing radiation effects in MOS oxides

    CERN Document Server

    Oldham, Timothy R

    1999-01-01

    This volume is intended to serve as an updated critical guide to the extensive literature on the basic physical mechanisms controlling the radiation and reliability responses of MOS oxides. The last such guide was Ionizing Radiation Effects in MOS Devices and Circuits, edited by Ma and Dressendorfer and published in 1989. While that book remains an authoritative reference in many areas, there has been a significant amount of more recent work on the nature of the electrically active defects in MOS oxides which are generated by exposure to ionizing radiation. These same defects are also critical

  14. 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.)

  15. 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.)

  16. 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

  17. 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.)

  18. Atoms in strong laser fields

    International Nuclear Information System (INIS)

    L'Huillier, A.

    2002-01-01

    When a high-power laser focuses into a gas of atoms, the electromagnetic field becomes of the same magnitude as the Coulomb field which binds a 1s electron in a hydrogen atom. 3 highly non-linear phenomena can happen: 1) ATI (above threshold ionization): electrons initially in the ground state absorb a large number of photons, many more than the minimum number required for ionization; 2) multiple ionization: many electrons can be emitted one at a time, in a sequential process, or simultaneously in a mechanism called direct or non-sequential; and 3) high order harmonic generation (HHG): efficient photon emission in the extreme ultraviolet range, in the form of high-order harmonics of the fundamental laser field can occur. The theoretical problem consists in solving the time dependent Schroedinger equation (TDSE) that describes the interaction of a many-electron atom with a laser field. A number of methods have been proposed to solve this problem in the case of a hydrogen atom or a single-active electron atom in a strong laser field. A large effort is presently being devoted to go beyond the single-active approximation. The understanding of the physics of the interaction between atoms and strong laser fields has been provided by a very simple model called ''simple man's theory''. A unified view of HHG, ATI, and non-sequential ionization, originating from the simple man's model and the strong field approximation, expressed in terms of electrons trajectories or quantum paths is slowly emerging. (A.C.)

  19. The MICE Demonstration of Muon Ionization Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lagrange, Jean-Baptiste [Imperial Coll., London; Hunt, Christopher [Imperial Coll., London; Palladino, Vittorio [INFN, Naples; Pasternak, Jaroslaw [Imperial Coll., London

    2016-06-01

    Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate muon ionization cooling, the technique proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam traverses a material (the absorber) loosing energy, which is replaced using RF cavities. The combined effect is to reduce the transverse emittance of the beam (transverse cooling). The configuration of MICE required to deliver the demonstration of ionization cooling is being prepared in parallel to the execution of a programme designed to measure the cooling properties of liquid-hydrogen and lithium hydride. The design of the cooling-demonstration experiment will be presented together with a summary of the performance of each of its components and the cooling performance of the experiment.

  20. Electron impact single ionization of copper

    Indian Academy of Sciences (India)

    Electron impact single ionization cross sections of copper have been calculated in the binary encounter approximation using accurate expression for as given by Vriens and Hartree–Fock momentum distribution for the target electron. The BEA calculation based on the usual procedure does not show satisfactory ...

  1. Radioisotopes and ionizing radiations in biological research

    International Nuclear Information System (INIS)

    1984-01-01

    This book deals with the use of radioisotopes and ionizing radiations in the various aspects of biological research. The following topics were presented: labelled compounds; conformation-function relationships of hormonal polypeptides and their spectroscopic study; neutron scattering and neutron diffraction for biological studies; high resolution autoradiography; radioimmunoassay; nuclear medicine; transfer of excitation energy in photosynthesis; radioagronomy; radiation preservation of food [fr

  2. 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

  3. 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.

  4. 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

  5. Relativistic soliton-like collisionless ionization wave

    Science.gov (United States)

    Arefiev, Alexey; McCormick, Matthew; Quevedo, Hernan; Bengtson, Roger; Ditmire, Todd

    2014-10-01

    It has been observed in recent experiments with laser-irradiated gas jets that a plasma filament produced by the laser and containing energetic electrons can launch a relativistic ionization wave into ambient gas. Here we present a self-consistent theory that explains how a collisionless ionization wave can propagate in a self-sustaining regime. A population of hot electrons necessarily generates a sheath electric field at the plasma boundary. This field penetrates the ambient gas, ionizing the gas atoms and thus causing the plasma boundary to expand. We show that the motion of the newly generated electrons can form a potential well adjacent to the plasma boundary. The outwards motion of the well causes a bunch of energetic electrons to become trapped, while allowing the newly generated electrons to escape into the plasma without retaining much energy. The resulting soliton-like ionizing field structure propagates outwards with a bunch of hot electrons that maintain a strong sheath field despite significant plasma expansion. We also present 1D and 2D particle-in-cell simulations that illustrate the described mechanism. The simulations were performed using HPC resources provided by the Texas Advanced Computing Center. This work was supported by NNSA Contract No. DE-FC52-08NA28512 and U.S. DOE Contract No. DE-FG02-04ER54742.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. Theory of multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    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

  12. 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

  13. 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

  14. Using of ionizing radiation in environment protection

    International Nuclear Information System (INIS)

    Kuruc, J.

    1997-01-01

    In this paper, there is given the review of application of the radiation chemistry techniques in the environment protection . Using of sources of ionization radiation in underground water, drinking water and waste waters as well as in exhaust gases radiation processing and treatment are reviewed [sk

  15. 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

  16. 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].

  17. Awareness of ionizing radiationamong medical students. | Okafor ...

    African Journals Online (AJOL)

    Objective: This is to assess the awareness of medical students who are the future medical practitioners of the sources, benefits and hazards of ionizing radiation. Method: This is a descriptive cross sectional study carried out among clinical medical students of Nnamdi Azikiwe university Nnewi campus. Data was collected ...

  18. 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

  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. 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.

  1. Intense-field photoionization of H2

    International Nuclear Information System (INIS)

    Allendorf, S.W.

    1991-01-01

    Studies of the interaction of intense lasers with molecules are not longer unusual. A number of workers are considering ionization and dissociation processes in these more complex systems. Several examples of the work in this field can be found elsewhere in this volume. Of particular interest is the importance of internal degrees of freedom in above threshold ionization (ATI). What are the roles played by vibration and rotation when a molecule is irradiated by an intense electric field? How are the molecular potentials affected by the laser? To date, most high intensity experiments on molecules have been performed with a limited range of laser wavelengths, either harmonic orders of Nd:YAG laser, excimer wavelengths, or nontunable colliding pulse mode-locked dye lasers. The effects of the intense field on the internal structure of molecules have been probed only when molecular resonances were fortuitously encountered on the way to dissociation or ionization. This paper concentrates on the truly molecular aspects of the molecule-laser interaction. We employ a tunable laser system, and we choose our wavelengths and intensities to probe regions of the molecular potential where a distribution of bond lengths exists. Systematically tuning our laser frequency allows us to examine specific intermediate state resonances in multiphoton ionization, and trace the behavior of the resonances in the presence of the intense laser field

  2. 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)

  3. 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.

  4. How does ionizing radiation escape from galaxies?

    Science.gov (United States)

    Orlitova, Ivana

    2016-10-01

    Search for sources that reionized the Universe from z 15 to z 6 is one of the main drivers of present-day astronomy. Low-mass star-forming galaxies are the most favoured sources of ionizing photons, but the searches of escaping Lyman continuum (LyC) have not been extremely successful. Our team has recently detected prominent LyC escape from five Green Pea galaxies at redshift 0.3, using the HST/COS spectrograph, which represents a significant breakthrough. We propose here to study the LyC escape of the strongest among these leakers, J1152, with spatial resolution. From the comparison of the ionizing and non-ionizing radiation maps, and surface brightness profiles, we will infer the major mode in which LyC is escaping: from the strongest starburst, from the galaxy edge, through a hole along our line-of-sight, through clumpy medium, or directly from all the production sites due to highly ionized medium in the entire galaxy. In parallel, we will test the predictive power of two highly debated indirect indicators of LyC leakage: the [OIII]5007/[OII]3727 ratio, and Lyman-alpha. We predict that their spatial distribution should closely follow that of the ionizing continuum if column densities of the neutral gas are low. This combined study, which relies on the HST unique capabilities, will bring crucial information on the structure of the leaking galaxies, provide constraints for hydrodynamic simulations, and will lead to efficient future searches for LyC leakers across a large range of redshifts.

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

    CERN Document Server

    Rothe, S; 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, Yu; Köster, U; Lane, J; 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 smallest 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, 9.317510(8) eV. New ab initio calculations were 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 super-heavy element 117, the heaviest homologue of astatine.

  6. 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.)

  7. Ionization equilibrium and equation of state of partially ionized hydrogen plasmas: Pseudopotential approach in chemical picture

    International Nuclear Information System (INIS)

    Arkhipov, Yu.V.; Baimbetov, F.B.; Davletov, A.E.

    2005-01-01

    Starting from the Bogolyubov hierarchy for the equilibrium distribution functions, a novel approach to the chemical model of partially ionized plasmas is proposed. Unlike the ordinary chemical picture it allows one to determine, in a self-consistent manner, both the ionization equilibrium and correlation functions as well. It is shown that the charged and neutral components of the plasma are closely interrelated and, as a consequence, the short-range order formation turns possible. The equation of state of partially ionized hydrogen plasmas is studied and detailed comparison with an exact quantum-mechanical expansion is made. The approach developed is quite analogous to the Debye-Hueckel theory of weakly coupled fully ionized plasmas and includes it as a limiting case

  8. Isotope analysis of U using surface ionization mass spectrometry

    International Nuclear Information System (INIS)

    Cesario, Jean

    Surface ionization mass spectrometry is a good technique for the determination of U isotope concentrations. The principles of the method are described: ionization, optical systems, measuring systems. The sensitivity and accuracy of the method are presented [fr

  9. 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

  10. 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

  11. 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.

  12. 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...

  13. 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

  14. 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

  15. Effect of two-center interference on molecular ionization in multiphoton ionization regime.

    Science.gov (United States)

    Hu, Shilin; Chen, Jing; Hao, Xiaolei; Li, Weidong; Guo, Li; Han, Shensheng

    2017-09-18

    Using solution of the full three-dimensional time-dependent Schrödinger equation (TDSE) in prolate spheroidal coordinates, we investigate the orientation dependence of ionization of H2+ in near-infrared laser fields. It is found that, the ionization probability decreases as a function of the alignment angle in tunneling ionization regime, while it ascends with the increase of orientation angle in multiphoton ionization regime for the internuclear distance R=2 a.u. Furthermore, the result obtained by the length gauge strong-field approximation theory is in qualitative agreement with that calculated by the TDSE but the radiation gauge strong-field approximation and molecular ADK theories fail to reproduce the TDSE result. Analysis indicates that the above intriguing feature can be ascribed to the interference between the partial electron wave packets emitted from different molecular cores, which becomes evident at low laser intensity due to increased width of the initial mechanical momentum of the photoelectron at ionization moment. In addition, when the internuclear distance increases to R=4 a.u., the ionization yields decrease vs alignment angle in both tunneling and multiphoton regimes since the electron wavefunction of the 1σg orbit is more concentrated in the molecular axis than that of R=2 a.u.

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

    International Nuclear Information System (INIS)

    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

  17. Positron impact ionization of atomic hydrogen at low energies

    Indian Academy of Sciences (India)

    impact ionization successfully. In particular, the close coupling calculations of Bray and. Stelbovics [7] and that of Kato and Watanabe [9] describe the total ionization cross section from near threshold to about 500 eV very accurately. Due to lack of experimental data, the study of positron impact ionization is till now.

  18. Calculation of Ionization Rate Coefficients of Heliumoide Iron | Dilmi ...

    African Journals Online (AJOL)

    We use a simple numerical method to generate the ionization rates starting from the cross sections. These last are obtained by code FAC (Flexible Atomic Code). Our computation results will be compared with those published. Keywords: Atomic data, radiative collisional Models, Ionization rate, cross Sections of ionization.

  19. 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)

  20. 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.

  1. 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 ...

  2. High order fluid model for ionization fronts in streamer discharges

    NARCIS (Netherlands)

    A. Markosyan (Aram); S. Dujko (Sasa); W. Hundsdorfer (Willem); U. Ebert (Ute)

    2011-01-01

    htmlabstractWhen non-ionized or lowly ionized matter is exposed to high electric fields, non-equilibrium ionization processes, streamer discharges, can develop. Streamers occur in nature and as well in many industrial applications such as the treatment of exhaust gasses, polluted water or biogas. A

  3. Single and double ionization of gallium by electron impact

    Indian Academy of Sciences (India)

    It is concluded that the ionization of 3d shell contributes partly to single ionization and partly to double ionization. The results so obtained show reasonably good agreement with the experimental data. Author Affiliations. L K Jha1. Department of Physics, L N T College, Muzaffarpur 842 002, India. Dates. Manuscript received ...

  4. 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

  5. Analysis of Laser Ionization and Ponderomotive Acceleration.

    Science.gov (United States)

    Hafizi, B.; Sprangle, P.; Moore, C. I.; Ting, A.

    1999-11-01

    Laser Ionization and Ponderomotive Acceleration (LIPA) is a new approach for the generation of electron beams from a gas. In this process an intense laser beam strips electrons from atoms, leading to a short pulse of relatively monoenergetic electrons with low emittance.(C.I. Moore et al.), Phys. Rev. Lett. 82, 1688 (1999). The energy of the electrons depends on the ponderomotive potential of the laser beam. Additionally the electrons emerge from the interaction region in directions that are correlated with the final energy. An analysis of LIPA based on tunneling ionization and subsequent classical motion is presented. Electron distribution functions are obtained for linear and circular polarization laser beams and compared with Monte Carlo simulations.

  6. 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.

  7. 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

  8. Upper Hybrid Effects in Artificial Ionization

    Science.gov (United States)

    Papadopoulos, K.; Eliasson, B. E.

    2014-12-01

    A most fascinating result of recent ionospheric experiments has been the discovery of artificial ionization by Pedersen et al. (GRL, 37, L02106, 2010). The Artificial Ionospheric Layers (AIL) were the result of F-region O-mode HF irradiation using the HAARP ionospheric heater operating at 3.6 MW power. As demonstrated by Eliasson et al. (JGR, 117, A10321, 2012) the physics controlling the observed phenomenon and its threshold can be summarized as: " Collisional ionization due to high energy (~ 20 eV) electron tails generated by the interaction of strong Langmuir turbulence with plasma heated at the upper hybrid resonance and transported at the reflection height". The objective of the current presentation is to explore the role of the upper hybrid heating in the formation of AIL and its implications to future experiments involving HF heaters operating in middle and equatorial latitudes.

  9. 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

  10. Electronic transport in partially ionized water plasmas

    Science.gov (United States)

    French, Martin; Redmer, Ronald

    2017-09-01

    We use ab initio simulations based on density functional theory to calculate the electrical and thermal conductivities of electrons in partially ionized water plasmas at densities above 0.1 g/cm3. The resulting conductivity data are then fitted to analytic expressions for convenient application. For low densities, we develop a simple and fully analytic model for electronic transport in low-density plasmas in the chemical picture using the relaxation-time approximation. In doing so, we derive a useful analytic expression for electronic transport cross sections with neutral particles, based on a model potential. In the regime of thermal ionization, electrical conductivities from the analytic model agree with the ab initio data within a factor of 2. Larger deviations are observed for the thermal conductivity, and their origin is discussed. Our results are relevant for modeling the interior and evolution of water-rich planets as well as for technical plasma applications.

  11. Low ionization source velocimetric smoke detector

    International Nuclear Information System (INIS)

    1980-01-01

    The low ionization source velocimetric smoke detector described is characterized in that the air ionization system is an alpha emitting radioactive source of very low intensity. This single source is inserted, without causing any corrosion couple, on both sides of a rigid partition separating into two equal volumes the space between the two polarized plates of an air capacitor. This then forms a reference chamber and an analytical chamber. As the assembly of chambers, source and metal frame is contained in an aerated sheet metal cage, the electric capacity of this capacitor varies when detections occur. The variations are sensed and amplified by a transistorized circuit that memorizes the electric background noises of the detector assembly as well as its slow variations and sorts them out from the variations due to the detection, by a simplified velocimetric electric measuring assembly connected upstream of a warning system that it controls [fr

  12. 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.

  13. Genetic variation in resistance to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, F.J.

    1989-01-01

    The very reactive superoxide anion O[sub 2] is generated during cell respiration as well as during exposure to ionizing radiation. Organisms have evolved different mechanisms to protect against the deleterious effects of reduced oxygen species. The copper-zinc superoxide dismutase is a eukaryotic cytoplasmic enzyme that protects the cell by scavenging superoxide radicals and dismutating them to hydrogen peroxide and molecular oxygen: 20[sub 2][sup [minus

  14. 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)

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. Miscellaneous applications of radioactivity and ionizing radiation

    International Nuclear Information System (INIS)

    Rafecas, I.

    2011-01-01

    Ionizing radiations, in its broadest sense, have numerous applications in widely different fields, some of which sometimes go unnoticed. Many of these applications are focused in the study of works of art or historical samples by nondestructive testing, applied to paintings, ceramics, carvings, metal, paper, mummified human/animal remains, etc, providing answer to questions as diverse as the authenticity or forgery of a work, its composition, the degree of deterioration. Others include radiocarbon dating, irradiation of gemstones, research, etc. (Author) 7 refs.

  3. 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.)

  4. 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

  5. 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.

  6. 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.)

  7. 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.

  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. 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

  10. 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.

  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. 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

  13. Laser-Induced Ionization Efficiency Enhancement On A Filament For Thermal Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Siegfried, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-14

    The evaluation of trace Uranium and Plutonium isotope ratios for nanogram to femtogram material quantities is a vital tool for nuclear counter-proliferation and safeguard activities. Thermal Ionization Mass Spectrometry (TIMS) is generally accepted as the state of the art technology for highly accurate and ultra-trace measurements of these actinide ratios. However, the very low TIMS ionization yield (typically less than 1%) leaves much room for improvement. Enhanced ionization of Nd and Sm from a TIMS filament was demonstrated using wavelength resonance with a nanosecond (pulse width) laser operating at 10 Hz when light was directed toward the filament.1 For this study, femtosecond and picosecond laser capabilities were to be employed to study the dissociation and ionization mechanisms of actinides/lanthanides and measure the enhanced ionization of the metal of interest. Since the underlying chemistry of the actinide/lanthanide carbides produced and dissociated on a TIMS filament is not well understood, the experimental parameters affecting the photodissociation and photoionization with one and two laser beams were to be investigated.

  14. 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

  15. 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

  16. 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

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

    Science.gov (United States)

    2016-12-01

    and identifying sources of smuggled nuclear material; however, it may also be used to determine a material’s origin in analysis of post detonation...RIMS analysis . Within this equation from [10], the desired cross section for ionization is contained. 21 U ion A ex N e N σ ω −  = −     18... analysis : 21 U ion A ex N e N σ ω −  = −     After the curve fitting was complete, the ionization probability model was executed and the results

  18. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    Science.gov (United States)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-01-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  19. Time-dependent studies of multiphoton processes

    International Nuclear Information System (INIS)

    Kulander, K.C.; Schafer, K.J.; Krause, J.L.

    1992-01-01

    Interest in intense-field laser-atom interactions has undergone very rapid growth over the past decade due to a number of very surprising observations made during short-pulse (much-lt 1 ns) excitation of atoms and molecules. Extensive results have been reported for electron and photon emission from atoms subject to high-intensity lasers. This wealth of data has greatly increased our detailed knowledge of the effects of electromagnetic radiation on the electrons in these systems. The richness of these results has encouraged the development of new theoretical methods to provide an understanding of the observations. This paper reports that one of the major techniques being used to study the dynamics of excitation and ionization is the direct solution of the time-dependent Schrodinger equation for an atom or molecule in a pulse laser field. The time-dependent methods allow the exact calculation of above-threshold ionization (ATI) spectra for real (three-dimensional) hydrogenic systems and of photon emission from atoms excited by lasers. Recently the possibility of high-frequency, high-intensity suppression of ionization has also been addressed

  20. 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).

  1. 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.

  2. Ionization pattern obtained in electrospray ionization or atmospheric pressure chemical ionization interfaces for authorized antidepressants in Romania

    Science.gov (United States)

    Grecu, Iulia; Ionicǎ, Mihai; Vlǎdescu, Marian; Truţǎ, Elena; Sultan, Carmen; Viscol, Oana; Horhotǎ, Luminiţa; Radu, Simona

    2016-12-01

    Antidepressants were found in 1950. In the 1990s there was a new generation of antidepressants. They act on the level of certain neurotransmitters extrasinpatic by its growth. After their mode of action antidepressants may be: SSRIs (Selective Serotonin Reuptake Inhibitors); (Serotonin-Norepinephrine Reuptake Inhibitors); SARIs (Serotonin Antagonist Reuptake Inhibitors); NRIs (Norepinephrine Reuptake Inhibitors); NDRIs (Norepinephrine-Dopamine Reuptake Inhibitors) NDRAs (Norepinephrine-Dopamine Releasing Agents); TCAs (Tricyclic Antidepressants); TeCAs (Tetracyclic Antidepressants); MAOIs (Monoamine Oxidase Inhibitors); agonist receptor 5-HT1A (5- hydroxytryptamine); antagonist receptor 5-HT2; SSREs (Selective Serotonin Reuptake Enhancers) and Sigma agonist receptor. To determine the presence of antidepressants in biological products, it has been used a system HPLC-MS (High Performance Liquid Chromatography - Mass Spectrometry) Varian 12001. The system is equipped with APCI (Atmospheric Pressure Chemical Ionization) or ESI (ElectroSpray Ionization) interface. To find antidepressants in unknown samples is necessary to recognize them after mass spectrum. Because the mass spectrum it is dependent on obtaining private parameters work of HPLC-MS system, and control interfaces, the mass spectra library was filled with the mass spectra of all approved antidepressants in Romania. The paper shows the mass spectra obtained in the HPLCMS system.

  3. 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

  4. Magnetic braking in weakly ionized media

    Science.gov (United States)

    Konigl, Arieh

    1987-01-01

    The combined magnetic braking-ambipolar diffusion problem in weakly ionized, rigidly rotating disks is studied. An analytical solution is presented for a disk whose angular velocity and magnetic yield vectors are aligned with the symmetry axis, illustrating the effects of the relative azimuthal drift of neutrals and ions. The effects of radial drift are added, commenting on the ratio of the characteristic ambipolar diffusion and magnetic braking time scales in high-mass and low-mass disks. A numerical calculation is used to show the combined action of these two processes.

  5. 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

  6. 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

  7. File: the monitoring of ionizing radiations use

    International Nuclear Information System (INIS)

    Lacoste, A.C.; Kalifa, G.; Muglioni, P.

    2001-01-01

    This file is devoted to the varied nuclear activities. The diversity implies different set of problems. Some of fields are well known such radiography or nuclear medicine but some ones are surprising. Beyond the diversity of uses there is the diversity of regulation texts. A part is related to the accidents and attests of the complexity of the control of ionizing radiations and the importance that can take the consequences of the less act of carelessness. The example of Finland is exposed. (N.C.)

  8. 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.)

  9. 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.

  10. 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.

  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. Waveshifters and Scintillators for Ionizing Radiation Detection

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-12-11

    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.

  13. 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)].

  14. 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

  15. Average local ionization energy: A review.

    Science.gov (United States)

    Politzer, Peter; Murray, Jane S; Bulat, Felipe A

    2010-11-01

    The average local ionization energy I(r) is the energy necessary to remove an electron from the point r in the space of a system. Its lowest values reveal the locations of the least tightly-held electrons, and thus the favored sites for reaction with electrophiles or radicals. In this paper, we review the definition of I(r) and some of its key properties. Apart from its relevance to reactive behavior, I(r) has an important role in several fundamental areas, including atomic shell structure, electronegativity and local polarizability and hardness. All of these aspects of I(r) are discussed.

  16. Nucleation in an ultra low ionization environment

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean

    at near atmospheric conditions. The chamber contains clean air with the addition of water vapour, ozone, and SO2. Using UV lights at 254 nm ozone is photolyzed, leading to the production of sulphuric acid and thus aerosols. An 18 MBq Caesium-137 gamma ray source with various amounts of lead in front...... Laboratory, located 1100 meters below ground, thus reducing the flux of ionizing cosmic radiation by six orders of magnitude. Similarly we have reduced the gamma background by shielding the experiment in lead and copper. Finally we have used air stored for several weeks and passed through an active charcoal...

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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)

  3. 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.

  4. Smart ionization chamber for gamma-ray monitoring

    Directory of Open Access Journals (Sweden)

    Drndarević Vujo R.

    2014-01-01

    Full Text Available A design and implementation of a smart ionization chamber suitable for connection into gamma radiation monitoring networks is presented in this paper. The smart ionization chamber consists of air-equivalent one liter ionization chamber with associated electronics and a built-in memory for storage of electronic data specifications. Generally, operating and measurement characteristics of the used ionization chamber are written into the memory chip attached to the chamber. A microcontroller-based data acquisition system with a mixed-mode interface has been implemented for the purpose of reading electronic data specifications from the memory chip, and for configuration and interfacing of the ionization chamber to the monitoring network using plug-and-play concept. The details of smart ionization chamber implementation and test results are included in the paper. [Projekat Ministarstva nauke Republike Srbije, br. TR36047 i br. TR32043

  5. 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

  6. Lattice design and expected performance of the Muon Ionization Cooling Experiment demonstration of ionization cooling

    Directory of Open Access Journals (Sweden)

    2017-06-01

    Full Text Available Muon beams of low emittance provide the basis for the intense, well-characterized neutrino beams necessary to elucidate the physics of flavor at a neutrino factory and to provide lepton-antilepton collisions at energies of up to several TeV at a muon collider. The international Muon Ionization Cooling Experiment (MICE aims to demonstrate ionization cooling, the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam passes through a material in which it loses energy. The energy lost is then replaced using rf cavities. The combined effect of energy loss and reacceleration is to reduce the transverse emittance of the beam (transverse cooling. A major revision of the scope of the project was carried out over the summer of 2014. The revised experiment can deliver a demonstration of ionization cooling. The design of the cooling demonstration experiment will be described together with its predicted cooling performance.

  7. 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.

  8. Ionization of Gas-Phase Polycyclic Aromatic Hydrocarbons in Electrospray Ionization Coupled with Gas Chromatography.

    Science.gov (United States)

    Cha, Eunju; Jeong, Eun Sook; Han, Sang Beom; Cha, Sangwon; Son, Junghyun; Kim, Sunghwan; Oh, Han Bin; Lee, Jaeick

    2018-03-20

    Herein, gas-phase polycyclic aromatic hydrocarbons (PAHs) as nonpolar compounds were ionized to protonated molecular ions [M + H] + without radical cations and simultaneously analyzed using gas chromatography (GC)/electrospray ionization (ESI)-tandem mass spectrometry (MS/MS). The ionization profile, dissociation, and sensitivity were first investigated to understand the significant behavior of gas-phase PAHs under ESI. The formation of protonated molecular ions of PAHs was distinguished according to the analyte phase and ESI spray solvents. The protonated PAHs exhibited characteristic dissociations, such as H-loss, H 2 -loss, and acetylene-loss, via competition of internal energy. In addition, GC/ESI-MS/MS resulted in relatively lower concentration levels (better sensitivity) for the limits-of-detection (LODs) of PAHs than liquid chromatography (LC)/ESI-MS/MS, and it seems to result from the characteristic ionization mechanism of the gas-phase analyte under ESI. Furthermore, the LODs of gas-phase PAHs depended on molecular weight and proton affinity (PA). Consequently, we demonstrated the relationship among the analyte phases, sensitivities, and structural characteristics (molecular weight and PA) under ESI. The gas-phase PAHs provided enhanced protonation efficiency and sensitivity using GC/ESI-MS/MS, as their molecular weight and PA increased. Based on these results, we offered important information regarding the behavior of gas-phase analytes under ESI. Therefore, the present GC/ESI-MS/MS method has potential as an alternative method for simultaneous analysis of PAHs.

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

    Science.gov (United States)

    Huang, Yunguang; Li, Jinxu; Tang, Bin; Zhu, Liping; Hou, Keyong; Li, Haiyang

    2015-01-01

    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. PMID:26587023

  10. ATMOSPHERIC-PRESSURE-IONIZATION MASS-SPECTROMETRY .1. INSTRUMENTATION AND IONIZATION TECHNIQUES

    NARCIS (Netherlands)

    BRUINS, AP

    Mass spectrometer ion sources are normally located inside a high-vacuum envelope. Such low-pressure ion sources can make use of a range of different ionization methods and are in routine use in analytical mass spectrometers. An ion source operating at atmospheric pressure is better suited, and may

  11. 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

  12. 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

  13. 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

  14. 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)

  15. 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.

  16. 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)

  17. Electrification of polymers by ionizing radiation

    International Nuclear Information System (INIS)

    Kimura, T.; Kinoshita, J.; Nagoya, M.; Koizumi, H.; Ichikawa, T.

    2006-01-01

    The amount of residual electric charge in polymer sheets after irradiation with electron and ion beams has been studied for preparing monopolar electret that can be used as a component of rewritable electronic paper displays. Irradiation of polymers with electron and ion beams leave excess positive charges in poly (methyl methacrylate), poly (styrene) and poly (ethylene) irrespective of the polarity of the injected charged particles. Irradiation of poly (vinylidene fluoride) with an electron beam leaves negative charges. The amount of remaining charges is less than 10-5 of the injected charges and is less than 10-7 of charges generated by ionizing radiations. These results indicate that the amount of positive and negative charges escaped from the polymers during the irradiation determines the polarity of the irradiated polymers. The amount of remaining charges initially increases with increasing radiation dose and then decreases rapidly decreases due to radiation-induced increase of the electric conductivity of the polymers. The leakage of the remaining charges is much slower for irradiated polymers than for triboelecrically charged ones. The rate of the leakage decreases with increasing energy of the charged beams. These results indicate that the excess charges remaining deeper in a polymer stays longer. It is therefore concluded that the electrification of polymer by ionizing radiation is a useful technique for obtaining long-lived monopolar electrets. (authors)

  18. 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)

  19. 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)

  20. 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)

  1. 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.

  2. 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)

  3. 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)

  4. 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)

  5. 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

  6. 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.

  7. First measurement of the ionization potential of astatine

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Sebastian [CERN, Geneva (Switzerland); Institut fuer Physik, Univ. Mainz (Germany); Andreyev, Andrei N. [University of the West of Scotland, Paisley (United Kingdom); Antalic, Stano [Comenius University, Bratislava (Slovakia); Cocolios, Thomas E.; Marsh, Bruce A.; Sjoedin, A. Marica; Fedosseev, Valentin N. [CERN, Geneva (Switzerland); Fedorov, Dimitry V. [PNPI, Gatchina (Russian Federation); Ghys, Lars; Huyse, Mark; Kudryavtsev, Yuri; Pauwels, Dieter; Radulov, Deyan; Duppen, Piet van [IKS, KU Leuven (Belgium); Lassen, Jens [TRIUMF, Vancouver (Canada); Raeder, Sebastian; Wendt, Klaus [Institut fuer Physik, Univ. Mainz (Germany); Seliverstov, Maxim [PNPI, Gatchina (Russian Federation); IKS, KU Leuven (Belgium); Venhart, Martin [Slovak Academy of Sciences, Bratislava (Slovakia)

    2011-07-01

    Since the discovery of element 85 in the year 1940 by D. R. Corson et al., the binding energy of the outer electron of astatine had not been determined. At the on-line isotope separator facility ISOLDE at CERN, Geneva radioactive isotopes of At were produced by impinging 1.4 GeV protons on a uranium carbide target, ionized using the Resonance Ionization Laser Ion Source (RILIS) and detected using alpha decay spectroscopy. In-source laser spectroscopy was performed in order to develop a multi-step ionization scheme for an efficient and highly selective At ion production, as requested by ISOLDE users. Two atomic transitions, previously observed by absorption spectroscopy were confirmed and assigned as first steps of the excitation and ionization scheme. A second laser beam was applied to non-resonantly ionize the excited At atoms. A wavelength scan of the ionizing step was performed to search for the ionization limit. From the observed ionization onset the first ionization potential of At was preliminary determined to be 9.3 eV. Results from these studies at CERN and consecutive measurements at TRIUMF, Canada and IKS, Belgium are presented.

  8. Time expansion chamber and single ionization cluster measurement

    International Nuclear Information System (INIS)

    Walenta, A.H.

    1978-10-01

    The time expansion chamber (TEC), a new type of drift chamber, allows the measurement of microscopic details of ionization. The mean drift time interval from subsequent sngle ionization clusters of a relativistic particle in the TEC can be made large enough compared to the width of a anode signal to allow the recording of the clusters separately. Since single primary electrons can be detected, the cluster counting would allow an improved particle separation using the relativistic rise of primary ionization. In another application, very high position accuracy for track detectors or improved energy resolution may be obtained. Basic ionization phenomena and drift properties can be measured at the single electron level

  9. Effects of ionizing radiation and steady magnetic field on erythrocytes

    International Nuclear Information System (INIS)

    Ivanov, S. P.; Galutzov, B. P.; Kuzmanova, M. A.; Markov, M. S.

    1996-01-01

    A complex biophysical test for studying the effects of ionizing and non-ionizing radiation has been developed. The following cell and membrane parameters have been investigated: cell size, cell shape, cell distribution by size, electrophoretic mobility, extent of hemolysis, membrane transport and membrane impedance. Gamma ray doses of 2.2 Gy and 3.3 Gy were used as ionizing radiation and steady (DC) magnetic field of 5-90 mT representing the non-ionizing radiation. Erythrocytes from humans and rats were exposed in vitro to both ionizing and non-ionizing radiation. In some experiments ionizing radiation was applied in vivo as well. Each of the simultaneously studied parameters have been found to change as a function of applied radiation. The proposed test allows an estimation of the changes in the elastic, rheological and electrical parameters of cells and biological membranes. Results indicate that ionizing radiation is significantly more effective in an in vivo application, while magnetic fields are more effective when applied in vitro. Surprisingly, steady magnetic fields were found to act as protector against some harmful effects of ionizing radiation. (authors)

  10. Near-threshold electron impact ionization of Ne and Xe

    International Nuclear Information System (INIS)

    Yates, B R; Khakoo, M A; Keane, K

    2009-01-01

    Doubly differential cross-sections for the single electron impact ionization of Ne and Xe have been measured at several energies below the second ionization energy. The results indicate that the ionization of Ne is strongly influenced by the polarization of the ionized 2 2 P 3/2,1/2 core, where as this influence is significantly reduced for Xe. Single differential cross-sections are derived from the doubly differential cross-sections and for Xenon these show profiles similar to Helium ('smile'), whereas for Neon they show a dissimilar profile ('frown').

  11. Positron ionization mass spectrometry: An organic mass spectrometrist's view

    International Nuclear Information System (INIS)

    Glish, G.L.; Donohue, D.L.; McLuckey, S.A.; Eckenrode, B.A.; Hulett, L.D. Jr.

    1990-01-01

    We are currently engaged in a research program to study the ionization of polyatomic molecules by positrons. We refer to the technique herein as positron ionization mass spectrometry which includes all of the possible ionization mechanisms. In the course of this work we will attempt to characterize each of the important ionization mechanisms. Our ultimate objective is to explore the use of positron ionization mass spectrometry for chemical analysis. Several other groups have also begun to pursue aspects of positron ionization in parallel with our efforts although with somewhat different approaches and, perhaps with slightly different emphases. Recently, for example, Passner et al. have acquired mass spectra in a Penning trap resulting from the ionization of several different polyatomic molecules by near thermal kinetics energy positrons. Our research involves studying the different types of ionizing interactions of positrons with organic molecules, as a function of positron kinetic energy. For ionization of polyatomic molecules by positrons, several possible mechanisms are apparent from lifetime and scattering cross-section data. These mechanisms are discussed

  12. Non-perturbative methods applied to multiphoton ionization

    International Nuclear Information System (INIS)

    Brandi, H.S.; Davidovich, L.; Zagury, N.

    1982-09-01

    The use of non-perturbative methods in the treatment of atomic ionization is discussed. Particular attention is given to schemes of the type proposed by Keldysh where multiphoton ionization and tunnel auto-ionization occur for high intensity fields. These methods are shown to correspond to a certain type of expansion of the T-matrix in the intra-atomic potential; in this manner a criterium concerning the range of application of these non-perturbative schemes is suggested. A brief comparison between the ionization rate of atoms in the presence of linearly and circularly polarized light is presented. (Author) [pt

  13. Substrate-Enhanced Micro Laser Desorption Ionization Mass Spectrometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne Research, Inc. and the University of Massachusetts at Amherst will collaborate to develop laser desorption ionization (LDI) mass spectrometric analysis of...

  14. Resonantly enhanced inner-orbital ionization in molecular iodine

    Science.gov (United States)

    Smith, Dale L.; Gibson, George N.

    2018-02-01

    We present a wavelength study of the strong-field single-electron ionization of molecular iodine near its one-photon B -state resonance at 530 nm. We have previously identified two ionization channels [Phys. Rev. A 95, 013410 (2017), 10.1103/PhysRevA.95.013410]: ionization of the high-lying molecular orbitals and ionization of the deep orbitals in I2. We find a resonant enhancement of both channels, although the peak enhancement occurs at different wavelengths for the different channels. Moreover, the branching ratio of the ionization of the deep orbitals shows a dispersion-like function, with the branching ratio of the deep orbitals reaching over 98% at 519 nm. Finally, the branching ratio of double ionization into an excited state of I22+ as a function of wavelength closely matches the branching ratio of the single ionization of deep orbitals, implying that excitation of molecular ions generally comes about through inner orbital ionization. These findings are inconsistent with current molecular ionization theory.

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

    International Nuclear Information System (INIS)

    Villarreal B, J.E.; Escobar A, L.; Camps, E.; Romero, S.; Gonzalez, P.; Salinas, B.

    2001-01-01

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

  16. Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous ionization

    International Nuclear Information System (INIS)

    Stoyanov, D G

    2007-01-01

    The elementary processes taking place in the formation of charged particles and their flow in parallel-plane, cylindrical and spherical geometry cases of ionization chamber are considered. On the basis of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage characteristic of an ionization chamber with homogeneous ionization is obtained. For the parallel-plane case comparision with experimental data is performed

  17. Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous 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)

    2007-11-15

    The elementary processes taking place in the formation of charged particles and their flow in parallel-plane, cylindrical and spherical geometry cases of ionization chamber are considered. On the basis of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage characteristic of an ionization chamber with homogeneous ionization is obtained. For the parallel-plane case comparision with experimental data is performed.

  18. Control and dynamics of attosecond electron wave packets in strong laser fields

    International Nuclear Information System (INIS)

    Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier; Lopez-Martens, R.; Valentin, C.; Balcou, P.; Kazamias, S.; Mauritsson, J.; Gaarde, M.B.; Schafer, K.J.; Mairess, Y.; Wabnitz, H.; Boutu, W.; Salieres, P.

    2005-01-01

    Full text: Trains of attosecond pulses, emerging from the phase-locking of high-order harmonics generated in a strong laser field are now being routinely produced and characterized in a few laser laboratories. Attosecond pulse trains (APTs) are flexible attosecond sources, since the amplitude and relative phase of the spectral components (the harmonics) can be tailored, allowing us to vary both the duration and the carrier frequency of the pulses. Attosecond pulses interacting with a gas of atoms generate electron wave packets (EWPs), which are temporally localized with approximately the same duration as the attosecond pulses. In contrast to the tunneling electron wave packets giving rise to processes such as high-order harmonic generation and above-threshold-ionization (ATI), the properties of these EWPs are inherited from the attosecond pulses through the single-photon ionization step. Thus the energy and temporal characteristics of the EWPs can be varied independently of the process under investigation, by controlling the properties of the attosecond pulses. This talk will describe two recent experiments done in Lund. First we report on the generation, compression and delivery on target of ultrashort extreme-ultraviolet light pulses using external amplitude and phase control. The APT is synthesized from the 13 th to 35 th harmonics of a 35 fs Ti:sapphire laser. The harmonics are generated by focusing the laser beam into a window-less gas cell, filled with argon. To achieve the required on-target attosecond pulses, the harmonics are filtered spatially, using a fixed aperture, and spectrally using aluminum filters. The aluminum filters also serve the purpose of compressing the attosecond pulses, using the negative group-delay dispersion of aluminum to compensate for the intrinsic positive chirp of the attosecond pulses. This experiment demonstrates a practical method for the synthesis and control of attosecond waveforms, and in this case the production of pulses

  19. Dynamic imaging of molecular motion ultrashort intense laser pulses

    Science.gov (United States)

    Bandrauk, Andre D.

    2002-05-01

    The nonlinear nonperturbative response of atoms in intense laser fields has been extensively studied both experimentally and theoretically in the past twenty years leading to new unexpected effects such as Above Threshold Ionization, ATI, high order frequency generation etc. and these are documented in recent book The similar studies of molecules is a new chapter in the pursuit of laser control and manipulation of molecules. The nonlinear nonperturbative response of molecules to intense (Icm2 ) and ultrashort (V10 fs) laser pulses [2] is expected to yield new effects due to the extra degrees of freedom nuclear motion as compared to atoms [3], such as creation of Laser Induced Molecular Potentials, LIMP' s, Charge Resonance Enhanced Ionization, CREI [4] and molecular High Order Harmonic Generation [5]. These nonlinear nonperturbative in effects were seen in experiments [6] and were predicted and confirmed by high-level numerical simulations of appropriate time-dependent Schrodinger equations [3-5,7], TDSE's, of molecules in laser fields. Our recent supercomputer simulations of H2+ molecule dynamics in intense laser fields, [7-9] based on TDSE, also allowed us to propose two new molecular imaging techniques: a) LCEI, Laser Coulomb Explosion Imaging [8] and b) LPEI, Laser Photoelectron Imaging [9]. The first is based on the analysis of the kinetic energy of molecular fragments after Coulomb Explosion, CE, whereas the latter imaging uses the shape of ATI electron peaks, produced by an intense laser pulse. We describe summarily in the present communication these two imaging methods which were developed using high level supercomputer simulations

  20. Dynamics of ionization in atomic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, S.Yu.; Ogurtsov, G.N.; Macek, J.H.; Gordeev, Yu.S

    2004-01-01

    The present state of the theoretical study of ionization in ion-atom and atom-atom collisions is reviewed on the basis of quantum mechanical approaches to the solution of the time-dependent Schroedinger equation. Perturbative theories as well as the methods employing exact numerical solutions of the Schroedinger equation, expansion of wave functions on atomic and molecular bases and Sturmian expansions are considered. Advantages and limitations of these methods are assessed for colliding systems with one 'active' electron, e.g. H{sup +}-H and He{sup 2+}-H. Comparison of calculations with available experimental data is given in a broad collision energy range. Perspectives for further developments are discussed.

  1. The ultrasound as a ionizing radiation

    International Nuclear Information System (INIS)

    Abrego L, J.F.

    2006-01-01

    Although, the ultrasonic technique is only an analytical tool for material prospecting, it has been developed to scientific level. In this work we are emphasizing on the natural frequency of the bodies; on the harmonics; and on the Fourier transforms. Also it was detected harmonics of 23 Gigahertz on a 5 Megahertz fundamental ultrasonic pulse, also it was verified the hematite and galena mineral disintegration by ultrasonic technique. And it is possible that the ultrasonic waves could be to promote of the electrons from one orbit to another and then to arrive to the original orbit and to verify the 'hot points' or 'hot spots'. May be it is the acoustic cavitation with temperatures of 5000 C. Also the ultrasonic technique was capable of fading the methylene blue and to induce an electric current on a de-ionized water. (Author)

  2. Ionization phenomena and sources of negative ions

    International Nuclear Information System (INIS)

    Alton, G.D.

    1983-01-01

    Negative ion source technology has rapidly advanced during the past several years as a direct consequence of the discovery of Krohn that negative ion yields can be greatly enhanced by sputtering in the presence of Group IA elements. Today, most negative ion sources use this discovery directly or the principles implied to effect negative ion formation through surface ionization. As a consequence, the more traditional direct extraction plasma and charge exchange sources are being used less frequently. However, the charge exchange generation mechanism appears to be as universal, is very competitive in terms of efficiency and has the advantage in terms of metastable ion formation. In this review, an attempt has been made to briefly describe the principal processes involved in negative ion formation and sources which are representative of a particular principle. The reader is referred to the literature for specific details concerning the operational characteristics, emittances, brightnesses, species and intensity capabilities of particular sources. 100 references

  3. Protection of wood with ionizing radiation

    International Nuclear Information System (INIS)

    Jokel, J.; Paserin, V.

    1975-01-01

    The method is described of accelerated killing of wood cells by ionizing radiation. From the conducted experiments the relation was derived for the resistance of these cells to the effects of high-energy gamma radiation and a relationship was ascertained between the level of the irradiation of live cells and the spread of tylosis in beech trees. Live wood cells may be killed by doses of up to 25 J/g (2.5 Mrad). The occurrence and formation rate of tylosis is restricted by doses between 0.25 J/g to 4.5 J/g. Doses of more than 4.5 J/g prevent the occurrence of tylosis. (J.K.)

  4. Ionization detector with improved radiation source

    International Nuclear Information System (INIS)

    Solomon, E.F.

    1977-01-01

    The detector comprises a chamber having at least one radiation source disposed therein. The chamber includes spaced collector plates which form a part of a detection circuit for sensing changes in the ionization current in the chamber. The radiation source in one embodiment is in the form of a wound wire or ribbon suitably supported in the chamber and preferably a source of beta particles. The chamber may also include an adjustable electrode and the source may function as an adjustable current source by forming the wire or ribbon in an eliptical shape and rotating the structure. In another embodiment the source has a random shape and is homogeneously disposed in the chamber. 13 claims, 5 drawing figures

  5. Ionization in a quantized electromagnetic field

    International Nuclear Information System (INIS)

    Gonoskov, I. A.; Vugalter, G. A.; Mironov, V. A.

    2007-01-01

    An analytical expression for a matrix element of the transition from a bound state of an electron in an atom to continuum states is obtained by solving the problem of interaction of the electron with a quantized electromagnetic field. This expression is used to derive formulas for the photoelectron spectrum and the rate of ionization of the simplest model atomic system upon absorption of an arbitrary number of photons. The expressions derived are analyzed and compared with the corresponding relationships obtained via other approaches. It is demonstrated that there are differences as compared to the case of the classical field. In particular, the photoelectron spectrum exhibits dips due to the destructive interference of the transition amplitudes in the quantized electromagnetic field

  6. The natural sources of ionizing radiation exposure

    International Nuclear Information System (INIS)

    Maximilien, R.

    1982-01-01

    Natural sources of ionizing radiation include external sources (cosmic rays, natural radionuclides present in the crust of the earth and in building materials) and internal sources (naturally occuring radionuclides in the human body, especially the potassium 40 and radon short lived decay products). The principal ways of human exposure to theses different components in ''normal'' areas are reviewed; some examples of the variability of exposure with respect to different regions of the world or the habits of life are given. Actual estimations of the doses delivered to the organs are presented; for the main contributors to population exposure, the conversion into effective dose equivalent has been made for allowing a better evaluation of their respective importance [fr

  7. 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 comprise as binding agents a mixture of A. at least 1 unsaturated olefin compound containing urethane groups, and B. at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound A. containing the urethane groups in a reaction product of (a) a compound of the general formula (CHR 1 = CR 2 COOCH 2 CH(OH)CH 2 O CO-)/sub n/R where n is 1 or 2, where R stands for a straight chain or branched alkyl group of valence n, where R 1 is hydrogen, methyl; or the group -COOCH 2 CH(OH)CH 2 OCOR 3 - where R 3 is a monovalent alkyl residue and where R 2 is hydrogen or methyl, and (b) a compound containing at least 1 isocyanate group where the mixture of (A) and (B) may contain conventional additives of the lacquer industry. 6 claims

  8. Ionizing Radiation as an Industrial Health Problem

    Science.gov (United States)

    Trewin, R. B.

    1964-01-01

    Ionizing radiation, first as x-rays, later in natural form, was discovered in Europe in the late 1890's. Immediate practical uses were found for these discoveries, particularly in medicine. Unfortunately, because of the crude early equipment and ignorance of the harmful effects of radiation, many people were injured, some fatally. Because of these experiences, committees and regulatory bodies were set up to study the problem. These have built up an impressive fund of knowledge useful in radiation protection. With the recent development of the peaceful uses of atomic energy, sources of radioactivity have appeared cheaply and in abundance. A rapidly growing number are finding industrial application. Because of their potential risk to humans, the industrial physician must acquire new knowledge and skills so that he may give proper guidance in this new realm of preventive medicine. The Radiation Protection Program of one such industry, the Hydro-Electric Power Commission of Ontario, is summarized. PMID:14105012

  9. Transport theory for relativistic ionized gases

    International Nuclear Information System (INIS)

    Georgiou, A.

    1985-01-01

    The phenomenological non-equilibrium thermodynamics is adapted to the description of relativistic multicomponent plasmas. The general and special forms of matter energy-momentum tensor are given and the physical meaning of the different terms are discussed. A delicate problem of such theories, the contribution of ionized components of plasmas to the electromagnetic energy-momentum tensor is analyzed and illustrated by special examples. The relativistic form of Gibbs equation leads to the balance equation of entropy density. The theory is compared to the nonrelativistic one. The linear transport equations are derived by assuming the linear dependence of currents on deviations. The thermodynamical fluxes and forces are identified and the interference of cross phenomena is discussed. (D.Gy.)

  10. Induced mutation of soy by ionization mutation

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.L.; Hsu, H.L.

    1975-09-01

    This article presents the results of experiments dealing with how 14 different doses of three types of ionization irradiation-roentgen rays, /sup 60/Co gamma rays, and thermal neutrons affect mutation of 14 types of soy beans and their hybrids. It was learned that with an increased dose the coefficient of seed germination decreases, the cotyledon becomes increasingly thicker, shoots develop more and more slowly, various deformities arise in the stalk, and fertility decreases. As far as M/sub 2/ mutation is concerned, a great variety has been discovered with regard to the height of the stem, the leaf formation, the color of the bloom, the color of the edge, the characteristics of the pod, the size of the seed and the color of the cicatrix. At the same time some specific characteristics having an important economic significance are being revealed, as for example, dwarf stems, the ability to withstand lodging, great pod density, increased inflorescence and short sprouts.

  11. Bacterial and archaeal resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Confalonieri, F; Sommer, S

    2011-01-01

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  12. Overview of Atmospheric Ionizing Radiation (AIR)

    Science.gov (United States)

    Wilson, J. W.; Maiden, D. L.; Goldhagen, P.; Tai, H.; Shinn, J. L.

    2003-01-01

    The SuperSonic Transport (SST) development program within the US was based at the Langley Research Center as was the Apollo radiation testing facility (Space Radiation Effects Laboratory) with associated radiation research groups. It was natural for the issues of the SST to be first recognized by this unique combination of research programs. With a re-examination of the technologies for commercial supersonic flight and the possible development of a High Speed Civil Transport (HSCT), the remaining issues of the SST required resolution. It was the progress of SST radiation exposure research program founded by T. Foelsche at the Langley Research Center and the identified remaining issues after that project over twenty-five years ago which became the launch point of the current atmospheric ionizing radiation (AIR) research project. Added emphasis to the need for reassessment of atmospheric radiation resulted from the major lowering of the recommended occupational exposure limits, the inclusion of aircrew as radiation workers, and the recognition of civil aircrew as a major source of occupational exposures. Furthermore, the work of Ferenc Hajnal of the Environmental Measurements Laboratory brought greater focus to the uncertainties in the neutron flux at high altitudes. A re-examination of the issues involved was committed at the Langley Research Center and by the National Council on Radiation Protection (NCRP). As a result of the NCRP review, a new flight package was assembled and flown during solar minimum at which time the galactic cosmic radiation is at a maximum (June 1997). The present workshop is the initial analysis of the new data from that flight. The present paper is an overview of the status of knowledge of atmospheric ionizing radiations. We will re-examine the exposures of the world population and examine the context of aircrew exposures with implications for the results of the present research. A condensed version of this report was given at the 1998

  13. Risks from ionizing radiation during pregnancy

    Directory of Open Access Journals (Sweden)

    mehrdad Gholami

    2007-04-01

    Full Text Available Gholami M1, Abedini MR2, Khossravi HR3, Akbari S4 1. Instructor, Department of medical physics, Faculty of medicine, Lorestan University of medical sciences 2. Assistant professor, Department of radiology, Faculty of medicine, Lorestan University of medical sciences 3. Assistant professor, Department of radiation protection, Iranian Atomic Energy Organization 4. Assistant professor, Department of gynecology, Faculty of medicine, Lorestan University of medical sciences Abstract Background: The discovery of the X-ray in November 1895 by the W. C. Roentgen caused the increasing use of x-ray, because of the benefits that patients get from the resultant the diagnosis. Since medical radiation exposure are mainly in artificial radiation sources, immediately after the x- ray discovery, progressive dermatitis and ophthalmic diseases were occurred in the early physicians and physicists. But delay effects were observed approximately 20 years after the x-ray discovery. History: Based on the studies, ionizing radiation is a potential hazard to the developing fetus, avoiding unnecessary radiation exposure to pregnant women is a standard practice in radiology, unless there are important clinical indications. Due to difference in stages of fetus development, using of the current radiation protection standards includes: justification of a practice, optimization of radiation protection procedures and dose limitation to prevent of serious radiation induced conditions is necessary. Conclusion: Conversely the somatic and genetic effects of x-rays, since the X-ray has the benefit effects, special in diagnostic and treatment procedures, there is increasing use of x-ray, so using of the latest radiation protection procedures is necessary. Radiation protection not only is a scientific subject but also is a philosophy, Moral and reasonable. since the ionizing radiation is a potential hazard to the developing fetus, avoiding unnecessary radiation exposure to the pregnant

  14. Low Dose Ionizing Radiation Modulates Immune Function

    International Nuclear Information System (INIS)

    Nelson, Gregory A.

    2016-01-01

    In order to examine the effects of low dose ionizing radiation on the immune system we chose to examine an amplified adaptive cellular immunity response. This response is Type IV delayed-type hypersensitivity also called contact hypersensitivity. The agent fluorescein isothiocyanate (FITC) is a low molecular weight, lipophilic, reactive, fluorescent molecule that can be applied to the skin where it (hapten) reacts with proteins (carriers) to become a complete antigen. Exposure to FITC leads to sensitization which is easily measured as a hypersensitivity inflammatory reaction following a subsequent exposure to the ear. Ear swelling, eosinophil infiltration, immunoglobulin E production and cytokine secretion patterns characteristic of a 'Th2 polarized' immune response are the components of the reaction. The reaction requires successful implementation of antigen processing and presentation by antigen presenting Langerhans cells, communication with naïve T lymphocytes in draining lymph nodes, expansion of activated T cell clones, migration of activated T cells to the circulation, and recruitment of memory T cells, macrophages and eosinophils to the site of the secondary challenge. Using this model our approach was to quantify system function rather than relying only on indirect biomarkers of cell. We measured the FITC-induced hypersensitivity reaction over a range of doses from 2 cGy to 2 Gy. Irradiations were performed during key events or prior to key events to deplete critical cell populations. In addition to quantifying the final inflammatory response, we assessed cell populations in peripheral blood and spleen, cytokine signatures, IgE levels and expression of genes associated with key processes in sensitization and elicitation/recall. We hypothesized that ionizing radiation would produce a biphasic effect on immune system function resulting in an enhancement at low doses and a depression at higher doses and suggested that this transition would occur in

  15. Low Dose Ionizing Radiation Modulates Immune Function

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Gregory A. [Loma Linda Univ., CA (United States)

    2016-01-12

    In order to examine the effects of low dose ionizing radiation on the immune system we chose to examine an amplified adaptive cellular immunity response. This response is Type IV delayed-type hypersensitivity also called contact hypersensitivity. The agent fluorescein isothiocyanate (FITC) is a low molecular weight, lipophilic, reactive, fluorescent molecule that can be applied to the skin where it (hapten) reacts with proteins (carriers) to become a complete antigen. Exposure to FITC leads to sensitization which is easily measured as a hypersensitivity inflammatory reaction following a subsequent exposure to the ear. Ear swelling, eosinophil infiltration, immunoglobulin E production and cytokine secretion patterns characteristic of a “Th2 polarized” immune response are the components of the reaction. The reaction requires successful implementation of antigen processing and presentation by antigen presenting Langerhans cells, communication with naïve T lymphocytes in draining lymph nodes, expansion of activated T cell clones, migration of activated T cells to the circulation, and recruitment of memory T cells, macrophages and eosinophils to the site of the secondary challenge. Using this model our approach was to quantify system function rather than relying only on indirect biomarkers of cell. We measured the FITC-induced hypersensitivity reaction over a range of doses from 2 cGy to 2 Gy. Irradiations were performed during key events or prior to key events to deplete critical cell populations. In addition to quantifying the final inflammatory response, we assessed cell populations in peripheral blood and spleen, cytokine signatures, IgE levels and expression of genes associated with key processes in sensitization and elicitation/recall. We hypothesized that ionizing radiation would produce a biphasic effect on immune system function resulting in an enhancement at low doses and a depression at higher doses and suggested that this transition would occur in the

  16. The first experience with LHC beam gas ionization monitor

    CERN Document Server

    Sapinski, M; Dehning, B; Guerrero, A; Patecki, M; Versteegen, R

    2012-01-01

    The Beam Gas Ionization Monitors (BGI) are used to measure beam emittance on LHC. This paper describes the detectors and their operation and discusses the issues met during the commissioning. It also discusses the various calibration procedures used to correct for non-uniformity of Multi-Channel plates and to correct the beam size for effects affecting the electron trajectory after ionization.

  17. The stellar content, metallicity and ionization structure of HII regions

    NARCIS (Netherlands)

    Martin-Hernandez, NL; Vermeij, R; Tielens, AGGM; van der Hulst, JM; Peeters, E

    Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of H II regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of Galactic and Magellanic Cloud H II regions observed by the

  18. Improvements in or relating to ionization smoke detectors

    International Nuclear Information System (INIS)

    Ryall, D.C.

    1979-01-01

    To overcome the tendency exhibited by ionization smoke detectors to false alarms, due to the entry of ionized particles into the outer chamber, the present invention describes an outermost guard electrode maintained at the same potential as the inner electrode. An operating circuit is given. (UK)

  19. Pressurized air ionization chamber with aluminium walls for radiometric dosimetry

    International Nuclear Information System (INIS)

    Rodrigues, R.G.S.; Pela, C.A.; Netto, T.G.

    1996-01-01

    A pressurized air ionization chamber with 23 cm 3 and aluminium walls is evaluated concerning its sensitiveness in low exposure rate. Considering conventional ionization chambers, this chamber shows a better performance since the air pressure of 2500 kPa minimizes the energy dependence to less than 5% between 40 and 1.250 keV

  20. Many-body Hamiltonian with screening parameter and ionization ...

    Indian Academy of Sciences (India)

    We prove the existence of a Hamiltonian with ionization energy as part of the eigenvalue, which can be used to study strongly correlated matter. This eigenvalue consists of total energy at zero temperature (0) and the ionization energy (). We show that the existence of this total energy eigenvalue, 0 ± , does not violate ...

  1. Is ionizing radiation regulated more stringently than chemical carcinogens

    International Nuclear Information System (INIS)

    Travis, C.C.; Pack, S.R.; Hattemer-Frey, H.A.

    1989-01-01

    It is widely believed that United States government agencies regulate exposure to ionizing radiation more stringently than exposure to chemical carcinogens. It is difficult to verify this perception, however, because chemical carcinogens and ionizing radiation are regulated using vastly different strategies. Chemical carcinogens are generally regulated individually. Regulators consider the risk of exposure to one chemical rather than the cumulative radiation exposure from all sources. Moreover, standards for chemical carcinogens are generally set in terms of quantities released or resultant environmental concentrations, while standards for ionizing radiation are set in terms of dose to the human body. Since chemicals and ionizing radiation cannot be compared on the basis of equal dose to the exposed individual, standards regulating chemicals and ionizing radiation cannot be compared directly. It is feasible, however, to compare the two sets of standards on the basis of equal risk to the exposed individual, assuming that standards for chemicals and ionizing radiation are equivalent if estimated risk levels are equitable. This paper compares risk levels associated with current standards for ionizing radiation and chemical carcinogens. The authors do not attempt to determine whether either type of risk is regulated too stringently or not stringently enough but endeavor only to ascertain if ionizing radiation is actually regulated more strictly than chemical carcinogens

  2. Ionizing radiation sensitivity of DNA polymerase lambda-deficient cells.

    NARCIS (Netherlands)

    Vermeulen, C.; Bertocci, B.; Begg, A.C.; Vens, C.

    2007-01-01

    Ionizing radiation induces a diverse spectrum of DNA lesions, including strand breaks and oxidized bases. In mammalian cells, ionizing radiation-induced lesions are targets of non-homologous end joining, homologous recombination, and base excision repair. In vitro assays show a potential involvement

  3. Positron impact ionization of atomic hydrogen at low energies

    Indian Academy of Sciences (India)

    Low energy positron impact ionization of atomic hydrogen is studies theoretically using the hyperspherical partial wave method of Das [1] in constant 12, equal energy sharing geometry. The TDCS reveal considerable differences in physics compared to electron impact ionization under the same geometry.

  4. Auto-ionizing states in MgI

    International Nuclear Information System (INIS)

    El-Sherbini, Th.M.; Rahman, A.A.

    1982-01-01

    Hartree-Fock calculations have been performed for the auto-ionizing levels of the 3pns, 3pnp, 4snp (n=4 to 7) and 3pnd (n=3 to 7) series in MgI. The calculated energies of the auto-ionizing states are compared with the available results from photo-absorption measurements and ejected-electron experiments. (author)

  5. Modeling of the bipolar transistor under different pulse ionizing radiations

    Science.gov (United States)

    Antonova, A. M.; Skorobogatov, P. K.

    2017-01-01

    This paper describes a 2D model of the bipolar transistor 2T312 under gamma, X-ray and laser pulse ionizing radiations. Both the Finite Element Discretization and Semiconductor module of Comsol 5.1 are used. There is an analysis of energy deposition in this device under different radiations and the results of transient ionizing current response for some different conditions.

  6. Dressed-state perturbation theory for multiphoton ionization of atoms

    International Nuclear Information System (INIS)

    Pan, L.; Sundaram, B.; Armstrong, L. Jr.

    1987-01-01

    We introduce a perturbation theory using dressed bound states to include higher-order transition processes in the calculation of atomic multiphoton ionization. We calculate the ionization probability of hydrogen atoms using this theory and compare the results with the lowest-order perturbation result. We also calculate the shift of the hydrogen atom's ground state that is due to the external field

  7. Exciton ionization in multilayer transition-metal dichalcogenides

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Latini, Simone; Thygesen, Kristian Sommer

    2016-01-01

    Photodetectors and solar cells based on materials with strongly bound excitons rely crucially on field-assisted exciton ionization. We study the ionization process in multilayer transition-metal dichalcogenides (TMDs) within the Mott-Wannier model incorporating fully the pronounced anisotropy...

  8. Many-body Hamiltonian with screening parameter and ionization ...

    Indian Academy of Sciences (India)

    Abstract. We prove the existence of a Hamiltonian with ionization energy as part of the eigenvalue, which can be used to study strongly correlated matter. This eigenvalue consists of total energy at zero temperature (E0) and the ionization energy (ξ). We show that the existence of this total energy eigenvalue, E0 ±ξ, does not ...

  9. Multistage ionization of atoms in a very strong electromagnetic field

    International Nuclear Information System (INIS)

    Krajnov, V.P.; Manykin, Eh.A.

    1980-01-01

    Considered is a problem of multiple ionization of middle and heavy atoms as a function of the intensity of an electromagnetic field. The atom is considered in the Thomas -Fermi approximation. Presented are estimates of ionization degree for lead, tungsten and tantalum

  10. Scattered ionizing radiations from low-energy focus plasma and ...

    Indian Academy of Sciences (India)

    Scattered ionizing radiation emissions from a low-energy plasma focus (0.1. kJ Mather-type) device ... widely used in personnel moni- toring (dosimetry) service for ionizing radiation, medical, industrial and research ... Thermoluminescence dosimeter (TLD-500) (high sensitivity, simple re-use and minimum fading) chips are ...

  11. Review of health effects of non-ionizing radiations | Ughachukwu ...

    African Journals Online (AJOL)

    Non-ionizing radiations (electromagnetic waves) consist of electric and magnetic waves travelling together. In decreasing order of wavelengths, they are classified into ultra long electromagnetic waves, radio waves, micro waves, infrared waves and visible rays. Man-made sources of non-ionizing radiation include electrical, ...

  12. Tagging multiphoton ionization events by two-dimensional photoelectron spectroscopy

    NARCIS (Netherlands)

    de Groot, Mattijs; Broos, Jaap; Buma, Wybren Jan

    2007-01-01

    Two-dimensional photoelectron spectroscopy has been used to supply process-specific labels to multiphoton ionization events. Employing these tags, the authors can construct excitation and photoelectron spectra along predefined excitation routes in the neutral manifold and ionization routes to the

  13. Ionization for reducing particulate matter emissions from poultry houses

    NARCIS (Netherlands)

    Cambra-López, M.; Winkel, A.; Harn, van J.; Ogink, N.W.M.; Aarnink, A.J.A.

    2009-01-01

    We evaluated the effect of ionization in reducing particulate and gaseous emissions in broiler houses and its effect on particle size distribution. Furthermore, we evaluated the performance of the tested ionization system and its influence on bird performance. The experiment was done during two

  14. Antiproton impact ionization of atomic hydrogen and helium

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 INN (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)

    2009-11-01

    We shall present results for antiproton ionization of H and He ranging from fully differential cross sections to total ionization. The calculations have been made in a coupled pseudostate impact parameter approximation. It will be shown that the interaction between the antiproton and the target nucleus is very important at low energies.

  15. The ionization of gamma-ray burst environments

    Science.gov (United States)

    Band, D. L.; Hartmann, D. H.

    1992-01-01

    If a gamma-ray burst (GRB) occurs in a neutral medium, ionizing radiation associated with the burst will flash-photoionize a region surrounding the source. Detection of the line emission from this ionized region can constrain the flux of ionizing radiation accompanying the GRB and the density and ionization state of the environment surrounding the burst source. If the medium is sufficiently dense then the ionized region will recombine and fade on human timescales, aiding in the detection of the burst location and further constraining the density of the medium. However, dust within the dense medium may attenuate the line flux; the burst is unlikely to melt the dust along the line-of-sight. Astronomically interesting flux limits can be established by observations with reasonable integration times on a major telescope (e.g., 3 meter or larger).

  16. Endoergic chemi-ionization in N-O collisions

    International Nuclear Information System (INIS)

    Nielsen, S.E.; Dahler, J.S.

    1979-01-01

    A semiclassical theory of endoergic chemi-ionization is developed and applied to the ionizing events that occur when ground state oxygen atoms collide with nitrogen atoms in the ground and first excited states. The approach used is an adaptation and extension of earlier theories due to Bardsley, Nakamura, and Miller. The theory relates the experimental associative (AI) and Penning ionization (PI) cross sections to the following events: formation of a stable diatomic ion (AI), neutral and ionized atomic fragments (PI), or of a metastable diatomic rotational resonance (DI, delayed ionization). The heavy particle motions are treated classically in terms of adiabatic potential energy functions, while localized nonadiabatic transitions also are taken into account by using the Landau-Zener approximation. Finally, the theoretical predictions compare well with the results of Ringer and Gentry's (1978) merged beam experiments

  17. Atom ionization in a nonclassical intense electromagnetic field

    International Nuclear Information System (INIS)

    Popov, A.M.; Tikhonova, O.V.

    2002-01-01

    The atoms ionization process in the intense nonclassical electromagnetic field is considered. It is shown that depending on the field quantum state the probability of ionization may essentially change even by one and the same average quantum number in the radiation mode, whereby the difference in the ionization rates is especially significant in the case, when the ionization process is of a multiphoton character. It is demonstrates in particular, that the nonclassical field may be considerably more intensive from the viewpoint of the atoms ionization, than the classical field with the same intensity. The peculiarities of the decay, related to the atomic system state in the strong nonclassical field beyond the perturbation theory frames are studied [ru

  18. Optical Imaging of Ionizing Radiation from Clinical Sources.

    Science.gov (United States)

    Shaffer, Travis M; Drain, Charles Michael; Grimm, Jan

    2016-11-01

    Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  19. Ionization fronts in coupled MHD-gas simulations

    Science.gov (United States)

    Wilson, A. D.; Diver, D. A.

    2017-09-01

    Partially ionized plasmas are ubiquitous in both nature and the laboratory, and their behaviour is best described by models which take into account the interactions between the neutral and charged species. We present a new non-linear, 3-dimensional, finite difference Gas-MHD Interactions Code designed to solve simultaneously the time evolution of fluid equations of both species in the conservation form as well as collisional interactions between them via appropriate choices of source term; in particular, we present results from this code in simulating Alfvén ionization in a partially ionized plasma. In this fashion, larger changes in the ionization fraction than were addressable in the linear limit are possible. Alfvén ionization is shown to impart plasmas with an inherent resistance to rapid recombination, where the recombination itself is significant enough to drive relative motion between the ionised and neutral species at speeds in excess of the critical velocity.

  20. Ionizing Energy Depositions After Fast Neutron Interactions in Silicon

    CERN Document Server

    Bergmann, Benedikt; Caicedo, Ivan; Kierstead, James; Takai, Helio; Frojdh, Erik

    2016-01-01

    In this study we present the ionizing energy depositions in a 300 μm thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-)monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy spectra. By separating the ionizing energy losses of the recoil silicon from energy depositions by products of nuclear reactions, the competition of ionizing (IEL) and non-ionizing energy losses (NIEL) of a recoil silicon within the silicon lattice was investigated. The data give supplementary information to the results of a previous measurement and are compared with different theoretical predictions.

  1. Physiological benefits from low levels of ionizing radiation

    International Nuclear Information System (INIS)

    Luckey, T.D.

    1982-01-01

    Extensive literature indicates that minute doses of ionizing radiation benefit animal growth and development, fecundity, health and longevity. Specific improvements appear in neurologic function, growth rate and survival of young, wound healing, immune competence, and resistance to infection, radiation morbidity, and tumor induction and growth. Decreased mortality from these debilitating factors results in increased average life span following exposure to minute doses of ionizing radiation. The above phenomena suggest the possibility that ionizing radiation may be essential for life. Limited data with protozoa suggest that reproduction rates decrease when they are maintained in subambient radiation environments. This may be interpreted to be a radiation deficiency. Evidence must now be obtained to determine whether or not ionizing radiation is essential for growth, development, nutrient utilization, fecundity, health and longevity of higher animals. Whether or not ionizing radiation is found to be essential for these physiologic functions, the evidence reviewed indicates that the optimal amount of this ubiquitous agent is imperceptibly above ambient levels. (author)

  2. Laser ablation/ionization studies in a glow discharge

    International Nuclear Information System (INIS)

    Hess, K.R.; Harrison, W.W.

    1985-01-01

    The pin cathode glow discharge is used in the laboratory as an atomization/ionization source for a variety of applications, including solids mass spectrometry. Coupled with a tunable dye laser, the glow discharge may also serve as an atom reservoir for resonance ionization mass spectrometry in which the laser ionizes the discharge sputtered atoms. By tightly focusing the laser onto solid samples, various ablation effects may also be investigated. The laser may be used to generate an ionized plasma which may be directly analyzed by mass spectrometry. Alternatively, the ablated neutral atoms may be used in post-ablation excitation/ionization processes, in this case the glow discharge. The results of these investigations are the basis of this paper

  3. Scientific colloquium on medical supervision of workers exposed to ionizing and non ionizing radiations

    International Nuclear Information System (INIS)

    1975-01-01

    The general principles of medical surveillance for workers exposed to ionizing radiation were defined in the Euratom Basic Standards in 1959. These principles, which are in accordance with the early IGRP publications, have been adopted by the national authorities and implemented without difficulty. However, because of the forthcoming publication of the revised Basic Standards- in accordance with recent IGRP recommendations, the Commission decided to organize a meeting of doctors responsible for the medical surveillance of workers exposed to ionizing radiation in order to disseminate as widely as possible the results of experience gained in the field of radiological protection and to pinpoint the practical difficulties which might arise when the principles were applied. The Commission also considered it important to inform doctors specializing in radiological protection about the principles to be followed by those responsible for the health protection of workers exposed to non-ionizing radiation, particularly microwaves and Laser beams. The complete text of each report in the original language is given in this volume

  4. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, Yu., E-mail: yuri.kudryavtsev@fys.kuleuven.be; Ferrer, R.; Huyse, M.; Van den Bergh, P.; Van Duppen, P. [Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven (Belgium); Vermeeren, L. [SCK-CEN, Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium)

    2014-02-15

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented.

  5. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopes.

    Science.gov (United States)

    Kudryavtsev, Yu; Ferrer, R; Huyse, M; Van den Bergh, P; Van Duppen, P; Vermeeren, L

    2014-02-01

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented.

  6. Quantitative analysis of copolymers : influence of the structure of the monomer on the ionization efficiency in electrospray ionization FTMS

    NARCIS (Netherlands)

    Koster, S.; Mulder, B.; Duursma, M.C.; Boon, J.J.; Philipsen, H.J.A.; Velde, J.W.; Nielen, M.W.F.; Koster, de C.G.; Heeren, R.M.A.

    2002-01-01

    The influence of the ionization efficiency on the measured copolymer sequence distribution is presented. Large differences in ionization efficiency were observed for mixtures of homopolyesters containing dipropoxylated bisphenol A/adipic acid and dipropoxylated bisphenol A/isophthalic acid and the

  7. Densely Ionizing Radiation Effects on the Microenvironment Promote Aggressive Trp53 Null Mammary Carcinomas

    Data.gov (United States)

    National Aeronautics and Space Administration — Densely ionizing radiation is a major component of the space radiation environment and has potentially greater carcinogenic effect compared to sparsely ionizing...

  8. Extremely-high vacuum pressure measurement by laser ionization

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    Laser ionization method has the very high sensitivity for detecting atoms and molecules. Hurst et al. successfully detected a single Cs atom by means of resonance ionization spectroscopy developed by them. Noting this high sensitivity, the authors have attempted to apply the laser ionization method to measure gas pressure, particularly in the range down to extremely high vacuum. At present, hot cathode ionization gauges are used for measuring gas pressure down to ultrahigh vacuum, however, those have a number of disadvantages. The pressure measurement using lasers does not have such disadvantages. The pressure measurement utilizing the laser ionization method is based on the principle that when laser beam is focused through a lens, the amount of atom or molecule ions generated in the focused space region is proportional to gas pressure. In this paper, the experimental results are presented on the nonresonant multiphoton ionization characteristics of various kinds of gases, the ion detection system with high sensitivity and an extremely high vacuum system prepared for the laser ionization experiment. (K.I.)

  9. Sources of ionizing radiation and their interactions with matter

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    Particles or photons are said to be ionizing if they are capable of removing electrons from matter. For this to happen, the energy per photon or the kinetic energy per particle must be greater than the minimum binding energy of the electrons of the medium. Radiation is thus ionizing relative to the medium. The main constituents of organic matter are carbon, oxygen, nitrogen, and hydrogen. The values of the primary ionization potentials (minimum energy required to remove the least bound electron from an atom) of these elements are: C : 11.24 eV; H : 13.60 eV; O : 13.57 eV; and N : 14.20 eV. The minimum energy required to remove an electron from a biological medium may in fact be less than these values; the binding energy of electrons in a molecule may be of the order of 10 eV, or even lower. The most energetic UV photons, those of wavelength 0.1 μm, have an energy of 12.4 eV, which is enough to ionize biological media. Similarly, X- and γ-rays are ionizing. However, the near UV, visible, IR, micro and radio waves are non-ionizing. In general, particles possessing a kinetic energy larger than 10 eV are ionizing

  10. Plasmadynamics and ionization kinetics of thermionic energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lawless, J.L. Jr.; Lam, S.H.

    1982-02-01

    To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)

  11. Effects of buffer ionization in protein transition volumes.

    Science.gov (United States)

    Lee, Soyoung; Heerklotz, Heiko; Chalikian, Tigran V

    2010-05-01

    Protein denaturation events are generally associated with a change in the state of ionization of abnormally titrating groups and, therefore, are coupled with changes in buffer ionization/neutralization equilibria. Consequently, buffer ionization should influence the measured change in volume accompanying protein denaturation. Changes in volume accompanying protein denaturation reflect the differential packing and hydration of polypeptide chains in their native and denatured conformations while also describing the pressure stability of proteins. A characteristic feature of conformational transitions of globular proteins is a near zero change in volume that is comparable in magnitude with the volume of ionization of biologically relevant buffers. Thus, the impact of buffer ionization on the volume of protein denaturation could be very significant with the potential to affect not only its magnitude but also its sign. To investigate this point quantitatively, we performed pressure perturbation calorimetric (PPC) studies of lysozyme and ribonuclease A at pH 3.0 in four buffers differing in their ionization volumes. Our results identify buffer ionization as an important determinant of protein transition volume that needs to be carefully taken into account. We emphasize that the importance of our results is not limited to PPC measurements but is more general and applies to all volumetric investigations, in particular, extending to the derivation of the pressure-temperature phase diagram of protein stability.

  12. Dissociative Ionization of Argon Dimer by Intense Femtosecond Laser Pulses.

    Science.gov (United States)

    Cheng, Qian; Xie, Xiguo; Yuan, Zongqiang; Zhong, Xunqi; Liu, Yunquan; Gong, Qihuang; Wu, Chengyin

    2017-05-25

    We experimentally and theoretically studied dissociative ionization of argon dimer driven by intense femtosecond laser pulses. In the experiment, we measured the ion yield and the angular distribution of fragmental ions generated from the dissociative ionization channels of (1,1) (Ar 2 2+ → Ar + + Ar + ) and (2,1) (Ar 2 3+ → Ar 2+ + Ar + ) using a cold target recoil ion momentum spectroscopy. The channel ratio of (2,1)/(1,1) is 4.5-7.5 times of the yield ratio of double ionization to single ionization of argon monomer depending on the laser intensity. The measurement verified that the ionization of Ar + is greatly enhanced if there exists a neighboring Ar + separated by a critical distance. In addition, the fragmental ions exhibit an anisotropic angular distribution with the peak along the laser polarization direction and the full width at half maximum becomes broader with increasing laser intensity. Using a full three-dimensional classical ensemble model, we calculated the angle-dependent multiple ionization probability of argon dimer in intense laser fields. The results show that the experimentally observed anisotropic angular distribution of fragmental ions can be attributed to the angle-dependent enhanced ionization of the argon dimer in intense laser fields.

  13. Dielectric barrier discharges applied for soft ionization and their mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Sebastian; Klute, Felix David; Schütz, Alexander; Franzke, Joachim, E-mail: joachim.franzke@isas.de

    2017-01-25

    Dielectric barrier discharges are used for analytical applications as dissociative source for optical emission spectrometry and for ambient-ionization techniques. In the range of ambient-ionization techniques it has attracted much attention in fields like food safety, biological analysis, mass spectrometry for reaction monitoring and imaging forensic identification. In this review some examples are given for the application as desorption/ionization source as well as for the sole application as ionization source with different sample introductions. It will be shown that the detection might depend on the certain distance of the plasma in reference to the sample or the kind of discharge which might be produced by different shapes of the applied high voltage. Some attempts of characterization are presented. A more detailed characterization of the dielectric barrier discharge realized with two ring electrodes, each separately covered with a dielectric layer, is described. - Highlights: • Dielectric barrier discharge applied as desorption/ionization source. • Dielectric barrier discharge applied solely as ionization source. • Different geometries in order to maintain soft ionization. • Characterization of the LTP probe. • Dielectric barrier discharges with two dielectric barriers (ring-ring shape).

  14. In-Source Laser Resonance Ionization at ISOL Facilities

    CERN Document Server

    Marsh, Bruce; Feddosseev, Valentin

    Resonance ionization laser ion source development has been carried out at two radioactive ion beam facilities: ISOLDE (CERN, Switzerland) and the IGISOL facility (Jyvaskyla, Finland). The scope of the Resonance Ionization Laser Ion Source has been extended to 27 elements with the development of new three-step ionization schemes for Sb, Sc, Dy, Y and Au. The efficiencies were determined to be in the range of 2 - 20 %. Additionally, a new two-step ionization scheme has been developed for bismuth in an off-line atomic beam unit. The scheme relies on ionization via a strong and broad auto-ionizing resonance at an energy of 63196.79 cm$^{−1}$. This scheme may offer an improvement over the existing RILIS efficiency and will be more convenient for use during resonance ionization spectroscopy of Bi isotopes. The RILIS can be used as a spectroscopic tool to probe features such as the hyperfine structures and the isotope-shifts of radioisotopes with low production rates. By coupling a laser scanning process that dire...

  15. Near-Threshold Ionization of Argon by Positron Impact

    Science.gov (United States)

    Babij, T. J.; Machacek, J. R.; Murtagh, D. J.; Buckman, S. J.; Sullivan, J. P.

    2018-03-01

    The direct single-ionization cross section for Ar by positron impact has been measured in the region above the first ionization threshold. These measurements are compared to semiclassical calculations which give rise to a power law variation of the cross section in the threshold region. The experimental results appear to be in disagreement with extensions to the Wannier theory applied to positron impact ionization, with a smaller exponent than that calculated by most previous works. In fact, in this work, we see no difference in threshold behavior between the positron and electron cases. Possible reasons for this discrepancy are discussed.

  16. Ionization and scintillation of nuclear recoils in gaseous xenon

    Energy Technology Data Exchange (ETDEWEB)

    Renner, J., E-mail: jrenner@lbl.gov [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Physics, University of California, Berkeley, CA 94720 (United States); Gehman, V.M.; Goldschmidt, A.; Matis, H.S.; Miller, T.; Nakajima, Y.; Nygren, D.; Oliveira, C.A.B.; Shuman, D. [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Álvarez, V. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Borges, F.I.G. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); Cárcel, S. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Castel, J.; Cebrián, S. [Laboratorio de Física Nuclear y Astropartículas, Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza (Spain); Cervera, A. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Conde, C.A.N. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); and others

    2015-09-01

    Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope α-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

  17. Device for the integral measurement of ionizing radiations

    International Nuclear Information System (INIS)

    Micheron, Francois.

    1980-01-01

    This invention relates to devices for the integral determination of ionizing radiations, particularly to the construction of a portable dosemeter. Portable measuring instruments have been suggested in the past, particularly dosemeters in which the discharge of a capacitor under the action of ionizing radiations is measured. Since the charge of a capacitor is not stable owing to dielectric imperfections, these measuring instruments have to be recalibrated at frequent intervals. To overcome this drawback, the invention suggests using the discharge of an electret, electrically charged to a pre-set initial value, under the action of ionizing radiations, as the transducer means of a dosemeter used in conjunction with display or warning systems [fr

  18. Effects of ionizing radiation on plant tissue cultures

    International Nuclear Information System (INIS)

    Hell, K.G.

    1978-01-01

    A short review is done of the biological effects of ionizing radiations on plant tissues kept in culture, from the work of Gladys King, in 1949, with X-ray irradiated tobacco. The role of plant hormones is discussed in the processes of growth inhibition and growth restoration of irradiated tissues, as well as morphogenesis. Radioresistance of cells kept in culture and the use of ionizing radiations as mutagens are also commented. Some aspects of the biological effects of ionizing radiations that need to be investigated are discussed, and the problem of genome instability of plant tissues kept in culture is pointed out. (M.A.) [pt

  19. Modelling of Collisional Ionization in Laser Excited Sodium Atoms

    Science.gov (United States)

    Mahmoud, M.; Gamal, Y.

    1995-12-01

    The time evolution of the energy distribution of the free electrons created by collisional ionization of sodium vapor resonantly excited with cw laser due to different physical mechanisms have been studied theoretically. The calculations clarified that the distribution of the electron energy tends to become non-Maxwellian for different periods of time. Also the computational model indicated that the major processes in the different stages of the plasma creation are purely collisional for both excitation and ionization. Moreover our calculations of energy spectra of electrons have characteristic peaks corresponding to associative ionization and superelastic collisions. A reasonable agreement with experiments is obtained.

  20. [Dosage of ionized calcium in osteo-articular pathology].

    Science.gov (United States)

    Eisinger, J; Schiano, A

    1978-06-01

    The dosage of calcium ionized serum using a selective electrode, was performed in a series of controls and patients with osteo-articular diseases. Normal values were 43 mg/l between 20 and 50 years of age, and 41 mg/l after 60 years. The level of ionized calcium, when given as a percentage of total blood calcium, did not decrease with age (normal value : 44%). It was increased in hyper-parathyroidism, rhumatoid polyarthritis and lytic bone metastasis. It did not vary in Paget's disease, osteoporosis, osteomalacia, condensing metastasis, Kahler's disease and spasmophilia. The ionized calcium in definitely diminished in hypoparathyroidism.

  1. Ionizing radiation source detection by personal TLD

    International Nuclear Information System (INIS)

    Marinkovic, O.; Mirkov, Z.

    2002-01-01

    The Laboratory for personal dosimetry has about 3000 workers under control. The most of them work in medicine. Some institutions, as big health centers, have different ionizing radiation sources. It is usefull to analyze what has been the source of irradiation, special when appears a dosimeter with high dose. Personal dosimetry equipment is Harshaw TLD Reader Model 6600 and dosimeters consist of two chips LiF TLD-100 assembled in bar-coded cards which are wearing in holders with one tissue-equivalent filter (to determine H(10)) and skin-equivalent the other (to determine H(0.07)). The calibration dosimeters have been irradiated in holders by different sources: x-ray (for 80keV and 100keV), 6 0C o, 9 0S r (for different distances from beta source) and foton beem (at radiotherapy accelerator by 6MeV, 10MeV and 18MeV). The dose ratio for two LiF cristals was calculated and represented with graphs. So, it is possible to calculate the ratio H(10)/H(0.07) for a personal TLD and analyze what has been the source of irradiation. Also, there is the calibration for determination the time of irradiation, according to glow curve deconvolution

  2. Ionization balance in EBIT and tokamak plasmas

    Science.gov (United States)

    Peacock, N. J.; Barnsley, R.; O'Mullane, M. G.; Tarbutt, M. R.; Crosby, D.; Silver, J. D.; Rainnie, J. A.

    2001-01-01

    The equilibrium state in tokamak core plasmas has been studied using the relative intensities of resonance x-ray lines, for example Lyα (H-like), "w" (He-like), and "q" (Li-like) from test ions such as Ar+15, Ar+16, and Ar+17. A full spatial analysis involves comparison of the line intensities with ion diffusion calculations, including relevant atomic rates. A zero-dimensional model using a global ion loss rate approximation has also been demonstrated by comparison with the data collected from a Johann configuration spectrometer with a charged coupled device (CCD) detector. Since the lines are nearly monoenergetic, their intensities are independent of the instrument sensitivity and are directly proportional to the ion abundances. This method has recently been applied to Ar in the Oxford electron beam ion trap (EBIT) with a beam energy in the range 3-10 keV. Taking into account the cross sections for monoenergetic electron collisions and polarization effects, model calculations agree with the observed line ratios at 4.1 keV beam energy. This work will be expanded to provide nomograms of ionization state versus line intensity ratios as a function of EBIT beam energy.

  3. Magnetic braking in weakly ionized circumstellar disks

    Science.gov (United States)

    Koenigl, A.

    1986-01-01

    Recent observations of disk-like mass distributions around newly formed stars have provided evidence for rapid rotation on scales similar to less than 0.1pc with specific angular momenta much higher than typical stellar values. A likely mechanism for the extraction of angular momentum from these regions is magnetic braking by means of Alfven waves that propagate into the lower-density ambient medium. However, because of the relatively high particle densities and the correspondingly low implied ionization fractions in these apparent disks, their constituent ions and neutrals need not be well coupled to each other and could develop large relative drift velocities. For this reason, previous treatments of magnetic braking that assumed perfect coupling between ions and neutrals have to be modified in this case. In particular, one has to take into account both the azimuthal drift that develops because only the ions are directly coupled to the magnetic field and the radial drift (or ambipolar diffusion) which leads to a redistribution (and leakage) of the magnetic flux. The results of a preliminary analysis of these effects are described.

  4. Ionizing radiation and medical personnel. I

    International Nuclear Information System (INIS)

    Wagnerova, M.; Skokanova, K.; Wagner, V.; Zikmundova, L.

    1977-01-01

    The levels were studied of immunoglobulins IgG, IgM and IgA in the blood serum and of IgA in the saliva of personnel of radiodiagnostic and nuclear medicine units in the Central Bohemian Region (Czechoslovakia). The purpose of the experiment was to find the effect of ionizing radiation on the immunity mechanism in man. It was observed that the average levels of immunoglobulins IgG and IgA were lower in personnel exposed to occupational radiation hazards than in the controls. Age dependent differences in the levels of IgG and IgA were not significant in the exposed personnel while the length of employment significantly affected the distribution curve which showed several peaks. Radiation doses little affected the immunoglobulin levels in the blood serum while the levels of IgA in the saliva showed a significant variation with the radiation dose. Age dependent and length of employment dependent differences were insignificant. The study thus verified different immunological behaviour induced by radiation in man. (L.O.)

  5. Non-Ionizing Radiation: Nature and Protection

    International Nuclear Information System (INIS)

    Abukasem, E.; Abdemalek, H.; Mosbah, D. S.

    2011-01-01

    Last century, the humanity witnessed a vast development, after the industrial revolution, in many aspects of life. There was a real revolution in world of communications, the electromagnetic waves were produced and used in many applications like wireless communications, radio and television transmissions, information transfer, medical diagnosis and many other useful applications. Non-ionizing radiation, the radiation which has no enough energy to remove an electron from an atom, becomes indispensable life necessity and currently it is a subject of public debate about its effects and hazards on human life and environments. The Arab Atomic Energy Agency recognized this fact and tried to raise the public awareness towards by organizing seminars, workshops and expert meetings in the Arab region in order to study the theoretical and applies aspects of this type of radiation as well as to shed the light on its possible hazards and effects on human life. This booklet came as a result of many expert meetings to be an Arabic simple and comprehensive guide line about the nature of and the different methods of protection from its possible effects and hazards.(author)

  6. Microwave Triggered Laser Ionization of Air

    Science.gov (United States)

    Vadiee, Ehsan; Prasad, Sarita; Jerald Buchenauer, C.; Schamiloglu, Edl

    2012-10-01

    The goal of this work is to study the evolution and dynamics of plasma expansion when a high power microwave (HPM) pulse is overlapped in time and space on a very small, localized region of plasma formed by a high energy laser pulse. The pulsed Nd:YAG laser (8 ns, 600mJ, repetition rate 10 Hz) is focused to generate plasma filaments in air with electron density of 10^17/cm^3. When irradiated with a high power microwave pulse these electrons would gain enough kinetic energy and further escalate avalanche ionization of air due to elastic electron-neutral collisions thereby causing an increased volumetric discharge region. An X-band relativistic backward wave oscillator(RBWO) at the Pulsed Power,Beams and Microwaves laboratory at UNM is constructed as the microwave source. The RBWO produces a microwave pulse of maximum power 400 MW, frequency of 10.1 GHz, and energy of 6.8 Joules. Special care is being given to synchronize the RBWO and the pulsed laser system in order to achieve a high degree of spatial and temporal overlap. A photodiode and a microwave waveguide detector will be used to ensure the overlap. Also, a new shadowgraph technique with a nanosecond time resolution will be used to detect changes in the shock wave fronts when the HPM signal overlaps the laser pulse in time and space.

  7. Ionizing particle detection based on phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Aly, Arafa H., E-mail: arafa16@yahoo.com, E-mail: arafa.hussien@science.bsu.edu.eg; Mehaney, Ahmed; Eissa, Mostafa F. [Physics Department, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt)

    2015-08-14

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  8. Decontamination of pesticide packing using ionizing radiation

    Science.gov (United States)

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

    2007-11-01

    The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry—GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.

  9. Atmospheric Ionizing Radiation (AIR) Project Review

    Science.gov (United States)

    Singleterry, R. C., Jr.; Wilson, J. W.; Whitehead, A. H.; Goldhagen, P. E.

    1999-01-01

    The National Council on Radiation Protection and Measurement (NCRP) and the National Academy of Science (NAS) established that the uncertainty in the data and models associated with the high-altitude radiation environment could and should be reduced. In response, the National Aeronautics and Space Administration (NASA) and the U.S. Department of Energy Environmental Measurements Laboratory (EML) created the Atmospheric Ionizing Radiation (AIR) Project under the auspices of the High Speed Research (HSR) Program Office at the Langley Research Center. NASA's HSR Program was developed to address the potential of a second-generation supersonic transport. A critical element focussed on the environmental issues, including the threat to crew and passengers posed by atmospheric radiation. Various international investigators were solicited to contribute instruments to fly on an ER-2 aircraft at altitudes similar to those proposed for the High Speed Civil Transport (HSCT). A list of participating investigators, their institutions, and instruments with quantities measured is presented. The flight series took place at solar minimum (radiation maximum) with northern, southern, and east/west flights. The investigators analyzed their data and presented preliminary results at the AIR Workshop in March, 1998. A review of these results are included.

  10. History of international symbol for ionizing radiation

    International Nuclear Information System (INIS)

    Franic, Z.

    1996-01-01

    The year 1996 marks the 50th anniversary of the radiation warning symbol as we currently know it. It was (except the colours used) doodled out at the University of California, Berkeley, sometime in 1946 by a small group of people. The key guy responsible was Nelson Garden, then the head of the Health Chemistry Group, at the Radiation Laboratory. The radiation warning symbol should not be confused with the civil defence symbol (circle divided into six equal sections, three of these being black and three yellow), designed to identify fallout shelters. The basic radiation symbol was eventually internationally standardized by ISO code: 361-1975 (E). Variations of this symbol are frequently used in logotypes radiation protection organizations or associations. Particularly nice are those of International Radiation Protection Association (IRPA) and Croatian Radiation Protection Association (CRPA) that combines traditional Croatian motives with high technology. However, apart from speculations, there is no definite answer why did the Berkeley people chose this particular symbol. Whatever the reason was, it was very good choice because the ionizing radiation symbol is simple, readily identifiable, i.e., not similar to other warning symbols, and discernible at a large distance. (author)

  11. Effects of prenatal exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Miller, R.W.

    1990-01-01

    Prenatal exposure to ionizing radiation induces some effects that are seen at birth and others that cannot be detected until later in life. Data from A-bomb survivors in Hiroshima and Nagasaki show a diminished number of births after exposure under 4 wk of gestational age. Although a wide array of congenital malformations has been found in animal experimentation after such exposure to x rays, in humans only small head size (exposure at 4-17 wk) and mental retardation (exposure primarily at 8-15 wk) have been observed. In Hiroshima, small head size occurred after doses of 0.10-0.19 Gy or more, and an excess of mental retardation at 0.2-0.4 Gy or more. Intelligence test scores were reduced among A-bomb survivors exposed at 8-15 wk of gestational age by 21-29 IQ points per Gy. Other effects of in-utero exposure to atomic radiation include long-lasting complex chromosome abnormalities

  12. Effects of prenatal exposure to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.W. (National Cancer Institute, Bethesda, MD (USA))

    1990-07-01

    Prenatal exposure to ionizing radiation induces some effects that are seen at birth and others that cannot be detected until later in life. Data from A-bomb survivors in Hiroshima and Nagasaki show a diminished number of births after exposure under 4 wk of gestational age. Although a wide array of congenital malformations has been found in animal experimentation after such exposure to x rays, in humans only small head size (exposure at 4-17 wk) and mental retardation (exposure primarily at 8-15 wk) have been observed. In Hiroshima, small head size occurred after doses of 0.10-0.19 Gy or more, and an excess of mental retardation at 0.2-0.4 Gy or more. Intelligence test scores were reduced among A-bomb survivors exposed at 8-15 wk of gestational age by 21-29 IQ points per Gy. Other effects of in-utero exposure to atomic radiation include long-lasting complex chromosome abnormalities.

  13. Non-ionizing radiation: an occupational apathy

    International Nuclear Information System (INIS)

    Mohd Yusof Mohd Ali

    2000-01-01

    Non-ionizing radiation, NIR, is widely used in various modern applications to the extent that its presence is common in some work places. However, due to inability of human beings to detect its presence make the radiation 'invisible' to the workers most of the time. Of late it is known that the radiation can be hazardous to human health if the exposure received is excessively high. Such proven health effects has led international organizations, such as, IRPA establishing standard guidelines and maximum permissible limits to control its exposure. Recent studies reveal that some work places do indicate the presence of the radiation at levels far exceeding the IRPA recommended limits. It is, therefore, the objective of this paper to highlight such hazardous situations, magnitude of the hazards involved and ways and means how to overcome the hazard so that workers can take necessary precaution and action to minimize the health risk associated with the hazard. However, due to time and space constraint, only five types of the NIR are elaborated in this paper, namely ELF, RF and microwave, UV, IR and laser

  14. Shakeoff Ionization near the Coulomb Barrier Energy

    Science.gov (United States)

    Sharma, Prashant; Nandi, T.

    2017-11-01

    We measure the projectile K x-ray spectra as a function of the beam energies around the Coulomb barrier in different collision systems. The energy is scanned in small steps around the barrier aiming to explore the nuclear effects on the elastically scattered projectile ions. The variation of the projectile x-ray energy with the ion-beam energies exhibits an unusual increase in between the interaction barrier and fusion barrier energies. This additional contribution to the projectile ionization can be attributed to the shakeoff of outer-shell electrons of the projectile ions due to the sudden nuclear recoil (˜10-21 sec ) caused by the attractive nuclear potential, which gets switched on near the interaction barrier energy. In the sudden approximation limit, the theoretical shakeoff probability calculation due to the nuclear recoil explains the observed data well. In addition to its fundamental interest, such processes can play a significant role in dark matter detection through the possible mechanism of x-ray emissions, where the weakly interacting massive particle-nucleus elastic scattering can lead to the nuclear-recoil-induced inner-shell vacancy creations. Furthermore, the present work may provide new prospects for atomic physics research at barrier energies as well as provide a novel technique to perform barrier distribution studies for two-body systems.

  15. Decontamination of pesticide packing using ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, C.L. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)], E-mail: clduarte@ipen.br; Mori, M.N.; Kodama, Yasko; Oikawa, H.; Sampa, M.H.O. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)

    2007-11-15

    The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry-GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.

  16. Electron impact ionization-excitation of Helium

    Science.gov (United States)

    Ancarani, Lorenzo Ugo; Gomez, A. I.; Gasaneo, G.; Mitnik, D. M.; Ambrosio, M. J.

    2016-09-01

    We calculate triple differential cross sections (TDCS) for the process of ionization-excitation of Helium by fast electron impact in which the residual ion is left in the n =2 excited state. We chose the strongly asymmetric kinematics used in the experiment performed by Dupré et al.. In a perturbative scheme, for high projectile energies the four-body problem reduces to a three-body one and, within that framework, we solve the time- independent Schrödinger equation with a Sturmian approach. The method, based on Generalized Sturmian Functions (GSF), is employed to obtain the initial ground state of Helium, the single-continuum state and the scattering wave function; for each of them, the GSF basis is constructed with the corresponding adequate asymptotic conditions. Besides, the method presents the following advantage: the scattering amplitudes can be extracted directly in the asymptotic region of the scattering solution, and thus the TDCS can be obtained without requiring a matrix element evaluation.

  17. Dissociative Ionization and Thermal Decomposition of Cyclopentanone.

    Science.gov (United States)

    Pastoors, Johan I M; Bodi, Andras; Hemberger, Patrick; Bouwman, Jordy

    2017-09-21

    Despite the growing use of renewable and sustainable biofuels in transportation, their combustion chemistry is poorly understood, limiting our efforts to reduce harmful emissions. Here we report on the (dissociative) ionization and the thermal decomposition mechanism of cyclopentanone, studied using imaging photoelectron photoion coincidence spectroscopy. The fragmentation of the ions is dominated by loss of CO, C 2 H 4 , and C 2 H 5 , leading to daughter ions at m/z 56 and 55. Exploring the C 5 H 8 O . + potential energy surface reveals hydrogen tunneling to play an important role in low-energy decarbonylation and probably also in the ethene-loss processes, yielding 1-butene and methylketene cations, respectively. At higher energies, pathways without a reverse barrier open up to oxopropenyl and cyclopropanone cations by ethyl-radical loss and a second ethene-loss channel, respectively. A statistical Rice-Ramsperger-Kassel-Marcus model is employed to test the viability of this mechanism. The pyrolysis of cyclopentanone is studied at temperatures ranging from about 800 to 1100 K. Closed-shell pyrolysis products, namely 1,3-butadiene, ketene, propyne, allene, and ethene, are identified based on their photoion mass-selected threshold photoelectron spectrum. Furthermore, reactive radical species such as allyl, propargyl, and methyl are found. A reaction mechanism is derived incorporating both stable and reactive species, which were not predicted in prior computational studies. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  18. Ionizing radiation effects on silicon test structures

    International Nuclear Information System (INIS)

    Kraner, H.W.; Beuttenmuller, R.; Chen, W.; Kierstead, J.A.; Li, Z.; Zhang, Y.; Dou, L.; Fretwurst, E.; Lindstroem, G.

    1993-12-01

    The effects of 60 Co gamma irradiation on MOSCAPS and special junction diode detectors have been studied. The capacitors were used to ellicit the charge accumulation and anneal in two types of thermally grown oxides representative of those used in routine detector processing. Ion implanted, oxide passivated junction detectors having 0.25 and 1 cm 2 areas and perimeter to area ratios of 1 (a square), 2 and 5 were designed and constructed to amplify the ionizing effects expected to largely affect junction edges through changes in fixed oxide charges. Detectors were exposed to over 4 Mrad and showed clear increases in leakage current in proportion to the junction edge length. Annealing schedules were determined to provide a continuous response to incremental irradiations and subsequent room temperature anneals of leakage current. Besides an increase in gate threshold, little effect on the C(V) response was found. PISCES simulation of the edge fields using different fixed oxide charge revealed regions of very high lateral fields near the junction edges for fixed charges in the 2 x 10 12 /cm 2 range expected from the capacitor studies which could be responsible for the observed leakage currents

  19. Sterilization by ionizing radiation comparative evaluation

    International Nuclear Information System (INIS)

    Tata, A.; Giuliani, S.

    1996-01-01

    Sterilization of surgical and medical devices by ionizing radiation (gamma or accelerated electron beams) is currently regarded as one of the main industrial-scale applications of radiation technology processes. Considering the most widely utilized chemical-physical methods (i.e. ethylene oxide (EtO) fumigation and radiation treatment), about 10-12 millions m(3) of surgical and medical devices are estimated to be processed yearly all around the world, of which 7 on beams. Due to the increasing demand for reusable and single-use devices, and the need of assuring their sterility in order to prevent, as much as possible, the diffusion of serious infective diseases (among which for instance Aids), the market of sterilization of these items is considerably expanding. In the general depicted scenario, radiation technologies are expected to gain a leading role, even a part from their economic attractiveness, as an alternative to EtO treatment, which is more and more considered as responsible for increasing environmental, social and public health problems

  20. Ionizing radiations: medical and industrial applications

    International Nuclear Information System (INIS)

    Vidal, H.

    1994-01-01

    Medical diagnosis with X-rays is the best known use of ionizing radiations on account of its wide diffusion (about 57 500 units in France). Other medical applications of artificial radionuclides involving a smaller number of installations are also well known, i.e. gamma teletherapy (167 units), brachytherapy (119 units) or therapy using unsealed sources (257 units). The industrial uses of ionising radiation, the diversity of which is very large, are generally less well known. The use of X- and gamma rays for non-destructive testing or food preservation and the use of tracers have some notoriety, but few people know that radioactive sources are involved in the measurement of parameters controlling industrial processes. The number of persons authorized to hold, use and/or sell artificial radionuclides amounts to about 4 800, all applications included. Approximately 650 of them are involved in therapy and 500 in medical research. The aim of this paper, which is not exhaustive, is to review a few typical applications of radionuclides both in the medical and industrial fields. It also supplies data both on the number of people authorized to use each technique and the radionuclides involved. (author). 10 tabs

  1. Collinear resonance ionization spectroscopy of radium ions

    CERN Multimedia

    We propose to study the neutron-deficient radium isotopes with high-resolution collinear resonance ionization spectroscopy. Probing the hyperfine structure of the $7{s}\\,^2\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{1/2}$ and $7{s}\\,^{2}\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{3/2}$ transitions in Ra II will provide atomic-structure measurements that have not been achieved for $^{{A}<208}$Ra. Measurement of the $7{s}\\,^{2}\\!{S}\\!_{1/2}\\,\\rightarrow\\,7{p}\\,^{2}\\!{P}\\!_{3/2}$ transition in $^{{A}<214}$Ra will allow the spectroscopic quadrupole moments to be directly measured for the first time. In addition, the technique will allow tentative spin assignments to be confirmed and the magnetic dipole moments measured for $^{\\textit{A}<208}$Ra. Measurement of the hyperfine structure (in particular the isotope shifts) of the neutron-deficient radium will provide information to further constrain the nuclear models away from the N=126 shell closure.

  2. Genetic variation in resistance to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, F.J.

    1992-01-01

    Results of an investigation of the gene coding for Cu, Zn superoxide dismutase (Sod) in Drosophila melanogaster seeking to understand the enzyme's role in cell protection against ionizing radiation are reported. Components of the investigation include molecular characterization of the gene; measuring the response of different genotypes to increasing levels of radiation; and investigation of the processes that maintain the Sod polymorphism in populations. While two alleles, S and F, are commonly found at the Sod locus in natural populations of D. melanogaster we have isolated from a natural population a null (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide a model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CAl. The radioprotective effects of SOD can be established by showing protective effects for the various genotypes that correspond to those inequalities. Because the allele variants studied are derived from natural populations, the proposed investigation avoids problems that arise when mutants obtained my mutagenesis are used. Moreover, each allele is studied in multiple genetic backgrounds, so that we correct for effects attributable to other loci by randomizing these effects.

  3. Systems and methods for cylindrical hall thrusters with independently controllable ionization and acceleration stages

    Science.gov (United States)

    Diamant, Kevin David; Raitses, Yevgeny; Fisch, Nathaniel Joseph

    2014-05-13

    Systems and methods may be provided for cylindrical Hall thrusters with independently controllable ionization and acceleration stages. The systems and methods may include a cylindrical channel having a center axial direction, a gas inlet for directing ionizable gas to an ionization section of the cylindrical channel, an ionization device that ionizes at least a portion of the ionizable gas within the ionization section to generate ionized gas, and an acceleration device distinct from the ionization device. The acceleration device may provide an axial electric field for an acceleration section of the cylindrical channel to accelerate the ionized gas through the acceleration section, where the axial electric field has an axial direction in relation to the center axial direction. The ionization section and the acceleration section of the cylindrical channel may be substantially non-overlapping.

  4. Study of gas ionization in a glow discharge and development of a micro gas ionizer for gas detection and analysis

    OpenAIRE

    Longwitz, Ralf G.

    2004-01-01

    In the pursuit of a portable gas detector/analyser we studied the components of an ion mobility spectrometer (IMS), which is a device that lends itself well to miniaturisation. The component we focused on was the ionizer. We fabricated a series of micro ionizers with micro electromechanical systems (MEMS) technology, which had a gap spacing between 1 and 50 μm and a thickness from 0.3 to 50 μm. They were used to examine micro discharges as such and as a means of ionization. In our measurement...

  5. Study of gas ionization in a glow discharge and development of a micro gas ionizer for gas detection and analysis

    OpenAIRE

    Longwitz, Ralf G.; Renaud, Philippe

    2005-01-01

    In the pursuit of a portable gas detector/analyser we studied the components of an ion mobility spectrometer (IMS), which is a device that lends itself well to miniaturisation. The component we focused on was the ionizer. We fabricated a series of micro ionizers with micro electromechanical systems (MEMS) technology, which had a gap spacing between 1 and 50 μm and a thickness from 0.3 to 50 μm. They were used to examine micro discharges as such and as a means of ionization. In our measurement...

  6. Rules and regulations on ionizing radiations sources installations

    International Nuclear Information System (INIS)

    1980-01-01

    The finality of this legislative text is to establish the standards and procedures for site, design, building, operation and decommissioning of nuclear installations, radioactive installations and ionizing radiations sources. This text include the commercialization of radioactive substances and equipment fabrication

  7. Production of highly ionized recoil ions in heavy ion impact

    International Nuclear Information System (INIS)

    Tawara, H.; Tonuma, T.; Be, S.H.; Shibata, H.; Kase, M.; Kambara, T.; Kumagai, H.; Kohno, I.

    1985-01-01

    The production mechanisms of highly ionized recoil ions in energetic, highly charged heavy ion impact are compared with those in photon and electron impact. In addition to the innershell ionization processes which are important in photon and electron impact, the electron transfer processes are found to play a key role in heavy ion impact. In molecular targets are also observed highly ionized monoatomic ions which are believed to be produced through production of highly ionized molecular ions followed by prompt dissociation. The observed N 6+ ions produced in 1.05MeV/amu Ar 12+ ions on N 2 molecules are produced through, for example, N 2 12+ *→N 6+ +N 6+ process. (author)

  8. Miniaturization of electrostatic ion engines by ionization and acceleration coupling

    Science.gov (United States)

    Ferrer, P.; Tchonang, M. P.

    2011-08-01

    We introduce a thruster concept where the same electric field is responsible for both ionization of the neutrals and acceleration of the ions, by letting the propellant gas escape into a high-field region through a thin, hollow needle at high electric potential. Ionization occurs via the corona mechanism. The configuration is very similar to the FEEP, the difference being in the ionization mechanism and the use of gaseous propellant. Although tests showed that such a thruster only ionizes a small fraction of the neutral gas (concept thruster was tested, whose mass was decent agreement. The tests were only suitable for initial data collection and the thruster only moderately resembled a working design, hence data such as efficiency cannot yet be meaningfully stated.

  9. Response of streamer tubes to higly ionizing particles

    International Nuclear Information System (INIS)

    Battistoni, G.; Bloise, C.; Liberatori, L.; Satta, L.

    1987-01-01

    The charge response of streamer tubes has been measured as a function of ionization power by exposure to relativistic ions. The results are discussed in view of the use of streamer tubes in the search for magnetic monopoles

  10. Mandatory certification of personal protection equipment against ionizing radiation

    International Nuclear Information System (INIS)

    Palacios, Tulio A.

    2000-01-01

    This paper analyze the regulations establishing mandatory certification of personal protection equipment, including those aim to protect against ionizing radiation due to the external irradiation and to the radioactive contamination. (author)

  11. Ionization and Coulomb explosion of small uranium oxide clusters

    International Nuclear Information System (INIS)

    Ross, Matt W; Castleman, A W Jr

    2012-01-01

    Femtosecond pulses are used to study the strong-field ionization and subsequent Coulomb explosion of small uranium oxide clusters. The resulting high atomic charge states are explored as a function of laser intensity and compared to ionization rates calculated using semi-classical tunneling theory with sequential ionization potential values. The gap in laser intensity between saturation intensity values for the 7s, 6d, and 5f orbitals are identified and quantified. Extreme charge states of oxygen up to O 4+ are observed indicating multiple ionization enhancement processes occurring within the clusters. The peak splittings of the atomic charge states are explored and compared to previous results on transition metal oxide species. Participation of the 5f orbitals in bonding is clearly identified based on the saturation intensity dependence of oxygen to uranium metal.

  12. Ionization of RNA-uracil by highly charged carbon ions

    Science.gov (United States)

    Champion, C.; Galassi, M. E.; Fojón, O.; Lekadir, H.; Hanssen, J.; Rivarola, R. D.; Weck, P. F.; Agnihotri, A. N.; Nandi, S.; Tribedi, L. C.

    2012-07-01

    We present a theoretical description of highly charged carbon ion-induced ionization of isolated RNA-uracil molecules. A comparison between recent experimental and theoretical total cross sections is provided.

  13. Summary of ionizing and displacive irradiation fields in various facilities

    International Nuclear Information System (INIS)

    Zinkle, S.J.; Greenwood, L.R.

    1993-01-01

    Calculations have been performed to estimate the ionizing and displacive irradiation fields that will occur in ceramics during irradiation in accelerators and fission and fusion reactors. A useful measure of the relative strength of ionizing vs. displasive radiation is the ratio of the absorbed ionizing dose to the displacement damage dose, which in the case of ion irradiation is equal to the ratio of the electronic stopping power to the nuclear stopping power. In ceramics such as Al 2 O 3 , this ratio is about 20 at a fusion reactor first wall, and has a typical value of about 100 in a fusion reactor blanket region and in mixed spectrum reactors such as HFIR. Particle accelerator sources typically have much higher ionizing to displacive radiation ratios, ranging from about 2000 for 1 MeV protons to >10,000 for 1 MeV electrons

  14. CIFOG: Cosmological Ionization Fields frOm Galaxies

    Science.gov (United States)

    Hutter, Anne

    2018-03-01

    CIFOG is a versatile MPI-parallelised semi-numerical tool to perform simulations of the Epoch of Reionization. From a set of evolving cosmological gas density and ionizing emissivity fields, it computes the time and spatially dependent ionization of neutral hydrogen (HI), neutral (HeI) and singly ionized helium (HeII) in the intergalactic medium (IGM). The code accounts for HII, HeII, HeIII recombinations, and provides different descriptions for the photoionization rate that are used to calculate the residual HI fraction in ionized regions. This tool has been designed to be coupled to semi-analytic galaxy formation models or hydrodynamical simulations. The modular fashion of the code allows the user to easily introduce new descriptions for recombinations and the photoionization rate.

  15. The primary processes by impact of ionizing radiations with water

    International Nuclear Information System (INIS)

    Znamirovschi, V.; Mastan, I.; Cozar, O.

    1976-01-01

    The problem concerning primary processes in radiolysis of water is discussed. The results on the excitation and ionization of water molecule, dissociation of the parent-molecular ion of water and dissociation of excited molecule of water are presented. (author)

  16. Ionization effects in three-dimensional solar granulation simulations

    Science.gov (United States)

    Rast, Mark P.; Nordlund, Ake; Stein, Robert F.; Toomre, Juri

    1993-01-01

    These numerical studies show that ionization influences both the transport and dynamical properties of compressible convection near the surface of the Sun. About two-thirds of the enthalpy transported by convective motions in the region of partial hydrogen ionization is carried as latent heat. The role of fast downflow plumes in total convective transport is substantially elevated by this contribution. Instability of the thermal boundary layer is strongly enhanced by temperature sensitive variations in the radiative properties of the fluid, and this provides a mechanism for plume initiation and cell fragmentation in the surface layers. As the plumes descend, temperature fluctuations and associated buoyancy forces are maintained because of the increased specific heat of the partially ionized material. This can result is supersonic vertical flows. At greater depths, ionization effects diminish, and the plumes are decelerated by significant entrainment of surrounding fluid.

  17. Ionization due to the interaction between two Rydberg atoms

    International Nuclear Information System (INIS)

    Robicheaux, F

    2005-01-01

    Using a classical trajectory Monte Carlo method, we have computed the ionization resulting from the interaction between two cold Rydberg atoms. We focus on the products resulting from close interaction between two highly excited atoms. We give information on the distribution of ejected electron energies, the distribution of internal atom energies and the velocity distribution of the atoms and ions after the ionization. If the potential for the atom is not purely Coulombic, the average interaction between two atoms can change from attractive to repulsive giving a Van de Graaff-like mechanism for accelerating atoms. In a small fraction of ionization cases, we find that the ionization leads to a positive molecular ion where all of the distances are larger than 1000 Bohr radii

  18. Fokker-Planck model for nonlocal impact ionization in semiconductors

    Science.gov (United States)

    Jacob, Biju; Robson, P. N.; David, J. P. R.; Rees, G. J.

    2001-08-01

    The probability distribution function (PDF) for impact ionization path length is a crucial quantity for understanding and modeling the low noise behavior of avalanche photodiodes with short multiplication regions. In such devices the ionization coefficient is no longer in equilibrium with the local electric field but depends on the carrier's history. The high electric fields needed to produce avalanche gain narrow the PDF, thereby reducing the randomness in ionization position and hence the noise in the multiplication. In this article we present a method for calculating PDFs using a Fokker-Planck model. The results are compared with those obtained from an equivalent Monte Carlo simulation employing a parabolic energy band, deformation potential optical phonon scattering, and a hard energy threshold for impact ionization.

  19. Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

    Science.gov (United States)

    Gilbert, Holly

    2010-01-01

    The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

  20. Ionization spectra of highly Stark-shifted rubidium Rydberg states

    Science.gov (United States)

    Grimmel, Jens; Stecker, Markus; Kaiser, Manuel; Karlewski, Florian; Torralbo-Campo, Lara; Günther, Andreas; Fortágh, József

    2017-07-01

    We report on the observation and numerical calculation of ionization spectra of highly Stark-shifted Rydberg states of rubidium beyond the classical ionization threshold. In the numerical calculations, a complex absorbing potential (CAP) allows us to predict the energy levels and ionization rates of Rydberg states in this regime. Our approach of adjusting the CAP to the external electric field reduces the number of free parameters from one per resonance to a single one. Furthermore, we have measured the ionization spectra of magneto-optically trapped rubidium atoms which are excited to principal quantum numbers of 43 and 70 at various electric fields. The emerging ions are detected using an ion optics. We find good agreement between the numerically and experimentally obtained spectra.