The ionisation parameter of star-forming galaxies evolves with the specific star formation rate

Science.gov (United States)

Kaasinen, Melanie; Kewley, Lisa; Bian, Fuyan; Groves, Brent; Kashino, Daichi; Silverman, John; Kartaltepe, Jeyhan

2018-04-01

We investigate the evolution of the ionisation parameter of star-forming galaxies using a high-redshift (z ˜ 1.5) sample from the FMOS-COSMOS survey and matched low-redshift samples from the Sloan Digital Sky Survey. By constructing samples of low-redshift galaxies for which the stellar mass (M*), star formation rate (SFR) and specific star formation rate (sSFR) are matched to the high-redshift sample we remove the effects of an evolution in these properties. We also account for the effect of metallicity by jointly constraining the metallicity and ionisation parameter of each sample. We find an evolution in the ionisation parameter for main-sequence, star-forming galaxies and show that this evolution is driven by the evolution of sSFR. By analysing the matched samples as well as a larger sample of z physically consistent with the definition of the ionisation parameter, a measure of the hydrogen ionising photon flux relative to the number density of hydrogen atoms.

Between atomic and nuclear physics: radioactive decays of highly-charged ions

International Nuclear Information System (INIS)

Atanasov, Dinko; Bosch, Fritz; Brandau, Carsten; Chen, Xiangcheng; Dillmann, Iris; Gao, Bingshui; Geissel, Hans; Hagmann, Siegbert; Hillenbrand, Pierre-Michel; Kozhuharov, Christophor; Litvinov, Sergey A; Litvinov, Yuri A; Münzenberg, Gottfried; Blaum, Klaus; Bühler, Paul; Faestermann, Thomas; Gernhäuser, Roman; Izumikawa, Takuji; Kurcewicz, Jan; Ma, Xinwen

2015-01-01

Highly charged radioactive ions can be stored for extended periods of time in storage rings which allows for precision measurements of their decay modes. The straightforward motivation for performing such studies is that fully ionised nuclei or few-electron ions can be viewed as clean quantum-mechanical systems, in which the interactions of the many electrons can be either excluded or treated precisely. Thus, the influence of the electron shell on the decay probability can be investigated. Another important motivation is stellar nucleosynthesis, which proceeds at high temperatures and the involved atoms are therefore highly ionised. Presented here is a compact review of the relevant experiments conducted at heavy-ion storage rings. Furthermore, we outline the perspectives for future experiments at new-generation storage-ring facilities. (paper)

Studies of the electron-impact double-ionisation process in magnesium using coincidence techniques

International Nuclear Information System (INIS)

Ford, M.J.

1998-01-01

This article will review recent measurements of the electron-impact double-ionisation of atomic magnesium. Results for the resonant Auger double-ionisation process with coincident detection of all three outgoing electrons, the (e, 3e) experiment, and for the direct double-ionisation process where only two outgoing electrons are detected, the (e, (3 -1)e) experiment, will be discussed. The results are analysed with reference to ionisation mechanisms and comparisons are made with calculated double-ionisation cross sections. Copyright (1998) CSIRO Australia

Isotope shifts in odd and even energy levels of the neutral and singly ionised gadolinium atom

International Nuclear Information System (INIS)

Ahmad, S.A.; Venugopalan, A.; Saksena, G.D.

1979-01-01

Isotope shift studies in the gadolinium spectra have been extended in the region 4140 to 4535 A. Isotope shift Δσ(156 to 160) have been measured in 315 lines of the neutral and singly ionised gadolinium atom using a recording Fabry-Perot Spectrometer and gadolinium samples enriched in 156 Gd and 160 Gd isotopes. Some of the Gd I lines studied involve transitions from newly identified high odd levels of 4f 8 6s6p, 4f 7 5d6s7s and 4f 7 5d 3 configurations to low even levels of 4f 8 6s 2 and 4f 7 6s 2 6p configurations. Electronic configurations of the energy levels have been discussed on the basis of observed isotope shifts. In some cases assigned configurations have been revised and probable configurations have been suggested. (author)

Ionization of a cesium atom by an absorption process involving two photons from a laser beam; Ionisation d'un atome de cesium par un processus d'absorption a deux photons issus d'un faisceau laser

Energy Technology Data Exchange (ETDEWEB)

Gontier, Y; Trahin, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-01-01

The expression giving the ionisation cross-section of an atom, by an absorption process involving two photons produced from a laser beam, is derived. The non-relativistic case is considered and the dipolar approximation used. The summation over the intermediate states is carried out rigorously by means of a special technique which is described in detail. A method is presented which makes it possible to obtain the numerical solution. (authors) [French] La formule donnant la section efficace d'ionisation d'un atome, par un processus d'absorption mettant en jeu deux photons issus d'un faiseau Laser, est etablie. On se place dans le cas non relativiste et Pon utilise l'approximation dipolaire. La sommation sur les etats intermediaires est effectuee rigoureusement au moyen d'une technique particuliere qui est decrite en detail. On expose une methode permettant d'obtenir la solution numerique. (auteurs)

Biological effects induced by K photo-ionisation in and near constituent atoms of DNA

International Nuclear Information System (INIS)

Touati, A.; Herve du Penhoot, M.A.; Fayard, B.; Champion, C.; Abel, F.; Gobert, F.; Lamoureux, M.; Politis, M.F.; Martins, L.; Ricoul, M.; Sabatier, L.; Sage, E.; Chetioui, A.

2002-01-01

In order to assess the lethal efficiency and other biological effects of inner shell ionisations of constituent atoms of DNA ('K' events), experiments were developed at the LURE synchrotron facility using ultrasoft X rays as a probe of K events. The lethal efficiency of ultrasoft X rays above the carbon K threshold was especially investigated using V79 cells and compared with their efficiency to induce double strand breaks in dry plasmid-DNA. A correlation between the K event efficiencies for these processes is shown. Beams of 340 eV were found to be twice as efficient at killing cells than were beams at 250 eV. In addition, a rough two-fold increase of the relative biological effectiveness for dicentric+ring induction has also been observed between 250 and 340 eV radiations. (author)

Proceedings. Protection of the natural environment. International symposium on ionising radiation

International Nuclear Information System (INIS)

Amiro, B.; Johansson, Gunnar; Larsson, Carl-Magnus; Luening, M.

1996-01-01

The symposium was organised jointly by the Swedish Radiation Protection Institute and the Atomic Energy Control Board of Canada. The programme was organised around six major topics: Biological effects of ionising radiation; Ecological effects of ionising radiation; Behaviour and transport of radionuclides in the natural environment; Criteria for environmental protection; Assessment methodology; and Social and economic aspects. All 86 contributions (excluding the opening addresses) have been separately indexed

Quantum coherence in photo-ionisation with tailored XUV pulses

Science.gov (United States)

Carlström, Stefanos; Mauritsson, Johan; Schafer, Kenneth J.; L'Huillier, Anne; Gisselbrecht, Mathieu

2018-01-01

Ionisation with ultrashort pulses in the extreme ultraviolet (XUV) regime can be used to prepare an ion in a superposition of spin-orbit substates. In this work, we study the coherence properties of such a superposition, created by ionising xenon atoms using two phase-locked XUV pulses at different frequencies. In general, if the duration of the driving pulse exceeds the quantum beat period, dephasing will occur. If however, the frequency difference of the two pulses matches the spin-orbit splitting, the coherence can be efficiently increased and dephasing does not occur.

The significance of a new correspondence principle for electromagnetic interaction in strong optical field ionisation

International Nuclear Information System (INIS)

Boreham, B. W.; Hora, H.

1997-01-01

We have recently developed a correspondence principle for electromagnetic interaction. When applied to laser interactions with electrons this correspondence principle identifies a critical laser intensity I*. This critical intensity is a transition intensity separating classical mechanical and quantum mechanical interaction regimes. In this paper we discuss the further application of I* to the interaction of bound electrons in atoms. By comparing I* with the ionisation threshold intensities as calculated from a cycle-averaged simple-atom model we conclude that I* can be usefully interpreted as a lower bound to the classical regime in studies of ionisation of gas atoms by intense laser beams

Application of resonance ionisation spectroscopy in atomic physics

International Nuclear Information System (INIS)

Kluge, H.J.

1997-01-01

Resonance ionization spectroscopy (RIS) and resonance ionization mass spectroscopy (RIMS) techniques have proved to be a powerful tool in atomic spectroscopy and trace analysis. Detailed atomic spectroscopy can be performed on samples containing less than 10 12 atoms. This sensitivity is especially important for investigating atomic properties of transuranium elements. RIMS is especially suitable for ultra trace determination of long lived radioactive isotopes. The extremely low detection limits allow analysis of samples in the sub-femtogram regime. High elemental and isotopic selectivity can be obtained. To produce isobarically pure ion beams, a RIS based laser ion source can be used

Atomic physics

International Nuclear Information System (INIS)

Armbruster, P.; Beyer, H.; Bosch, F.; Dohmann, H.D.; Kozhuharov, C.; Liesen, D.; Mann, R.; Mokler, P.H.

1984-01-01

The heavy ion accelerator UNILAC is well suited to experiments in the field of atomic physics because, with the aid of high-energy heavy ions atoms can be produced in exotic states - that is, heavy atoms with only a few electrons. Also, in close collisions of heavy ions (atomic number Z 1 ) and heavy target atoms (Z 2 ) short-lived quasi-atomic 'superheavy' systems will be formed - huge 'atoms', where the inner electrons are bound in the field of the combined charge Z 1 + Z 2 , which exceeds by far the charge of the known elements (Z <= 109). Those exotic or transient superheavy atoms delivered from the heavy ion accelerator make it possible to study for the first time in a terrestrial laboratory exotic, but fundamental, processes, which occur only inside stars. Some of the basic research carried out with the UNILAC is discussed. This includes investigation of highly charged heavy atoms with the beam-foil method, the spectroscopy of highly charged slow-recoil ions, atomic collision studies with highly ionised, decelerated ions and investigations of super-heavy quasi-atoms. (U.K.)

Ionization of a cesium atom by an absorption process involving two photons from a laser beam; Ionisation d'un atome de cesium par un processus d'absorption a deux photons issus d'un faisceau laser

Energy Technology Data Exchange (ETDEWEB)

Gontier, Y.; Trahin, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-01-01

The expression giving the ionisation cross-section of an atom, by an absorption process involving two photons produced from a laser beam, is derived. The non-relativistic case is considered and the dipolar approximation used. The summation over the intermediate states is carried out rigorously by means of a special technique which is described in detail. A method is presented which makes it possible to obtain the numerical solution. (authors) [French] La formule donnant la section efficace d'ionisation d'un atome, par un processus d'absorption mettant en jeu deux photons issus d'un faiseau Laser, est etablie. On se place dans le cas non relativiste et Pon utilise l'approximation dipolaire. La sommation sur les etats intermediaires est effectuee rigoureusement au moyen d'une technique particuliere qui est decrite en detail. On expose une methode permettant d'obtenir la solution numerique. (auteurs)

Symmetric Atom–Atom and Ion–Atom Processes in Stellar Atmospheres

Directory of Open Access Journals (Sweden)

Vladimir A. Srećković

2017-12-01

Full Text Available We present the results of the influence of two groups of collisional processes (atom–atom and ion–atom on the optical and kinetic properties of weakly ionized stellar atmospheres layers. The first type includes radiative processes of the photodissociation/association and radiative charge exchange, the second one the chemi-ionisation/recombination processes with participation of only hydrogen and helium atoms and ions. The quantitative estimation of the rate coefficients of the mentioned processes were made. The effect of the radiative processes is estimated by comparing their intensities with those of the known concurrent processes in application to the solar photosphere and to the photospheres of DB white dwarfs. The investigated chemi-ionisation/recombination processes are considered from the viewpoint of their influence on the populations of the excited states of the hydrogen atom (the Sun and an M-type red dwarf and helium atom (DB white dwarfs. The effect of these processes on the populations of the excited states of the hydrogen atom has been studied using the general stellar atmosphere code, which generates the model. The presented results demonstrate the undoubted influence of the considered radiative and chemi- ionisation/recombination processes on the optical properties and on the kinetics of the weakly ionized layers in stellar atmospheres.

Critical ionisation velocity effects in astrophysical plasmas

International Nuclear Information System (INIS)

Raadu, M.A.

1979-08-01

Critical ionisation velocity effects are relevant to astrophysical situations where neutral gas moves through a magnetised plasma. The experimental significance of the critical velocity is well established and the physical basis is now becoming clear. The underlying mechanism depends on the combined effects of electron impact ionisation and electron energisation by collective plasma interactions. For low density plasmas a theory based on a circular process involving electron heating through a modified two stream instability has been developed. Several applications of critical velocity effects to astrophysical plasmas have been discussed in the literature. The importance of the effect in any particular case may be determined from a detailed consideration of energy and momentum balance, using appropriate atomic rate coefficients and taking full account of collective plasma processes. (Auth.)

A self-calibrating ionisation chamber for the precise intensity calibration of high-energy heavy-ion beam monitors

International Nuclear Information System (INIS)

Junghans, A.

1996-01-01

The intensity of a 136 Xe(600 A MeV) beam has been determined by simultaneously measuring the particle rate and the corresponding ionisation current with an ionisation chamber. The ionisation current of this self-calibrating device was compared at higher intensities with the current of a secondary-electron monitor and a calibration of the secondary-electron current was achieved with a precision of 2%. This method can be applied to all high-energy heavy-ion beams. (orig.)

Making ionising radiation a real experience for high school science students

International Nuclear Information System (INIS)

Whitlock, J.; Lang, P.; De La Matter, D.; Hinman, P.; White, B.

2009-01-01

The Canadian public has little understanding of ionising radiation due in part to its treatment in popular media. In principle, students learn about ionising radiation in their school science classes. Developments in science curricula are providing more education opportunities for this subject. The Canadian Nuclear Society's program for introducing real, personal experience with ionising radiation in the classroom is starting to make a difference. The demand is expected to exceed the resources of the CNS and the program is being developed to facilitate external support. This paper summarizes the need, the history of this program development, and the path forward. (author)

Atmospheric ionisation in Snowdonia

Energy Technology Data Exchange (ETDEWEB)

Aplin, K L [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH UK (United Kingdom); Williams, J H, E-mail: k.aplin1@physics.ox.ac.uk [Envirodata-Eyri, Bryn Goleu, Penmaen Park, Llanfairfechan, Gwynedd LL33 0RL (United Kingdom)

2011-06-23

Atmospheric ionisation from natural radioactivity and cosmic rays has been measured at several sites in Snowdonia from 2005-present. The motivation for this project was a combination of public engagement with science, and research into the effects of ionisation on climate. A four-component atmospheric radiometer instrument is co-located with the ionisation detectors and the data is remotely logged and displayed on the Web. Atmospheric ionisation from natural radioactivity varies with local geology, and the cosmic ray ionisation component is modulated by solar activity and altitude. Variations due to all these effects have been identified and are described.

XUV spectra of highly ionised molybdenum

Energy Technology Data Exchange (ETDEWEB)

Mansfield, M W.D.; Peacock, N J; Smith, C C; Hobby, M G [UKAEA, Abingdon. Culham Lab.; Cowan, R D

1978-05-14

The spectra of molybdenum ions produced in Tokamaks in the wavelength range 10-200 A have been reproduced in a plasma formed by laser beam irradiation of solid molybdenum targets. Lines from highly ionised stages of molybdenum (Mo XXX to Mo XXXII) have been distinguished by varying the laser beam intensity. Detailed analyses of the simpler ions, Mo XV (Ni-like), Mo XVI (Co-like), Mo XXXII (Na-like), and to a lesser extent Mo XXXI (Mg-like) and Mo XVII (Fe-like), have been achieved by comparison with ab initio calculations. A general interpretation of intermediate ion stages is also given but it is shown that most of these spectra are so complex, as a result of inner-subshell excitation, that detailed term-scheme analyses are nearly impossible.

Generator for ionising radiation

International Nuclear Information System (INIS)

Romanovsky, V.F.; Panasjuk, V.S.; Stepanov, B.M.; Ovcharov, A.M.; Akimov, J.A.

1979-01-01

The generator for ionising radiation wherein a transmitter for ionising radiation contains a resonance transformer wherein the field coil is composed of a low voltage outside portion and a transformer coil, electrically connected with an electrically conducting housing of the resonance transformer, and an acclerating tube wherein the high voltage electrode is coupled with the high voltage end of the transformer coil of the resonance transformer and fixed to one of the ends of the tubular insulator of the accelerator tube, wherein the low voltage electrode is electrically connected with the housing of the resonance transformer and a source of charged particles is introduced into the evacuated inner space of the acceleration tube and electrically connected with one of the electrodes thereof, is described. (G.C.)

Exotic highly ionising particles at the LHC

CERN Document Server

De Roeck, A; Mermod, P; Milstead, D; Sloan, T

2012-01-01

The experiments at the Large Hadron Collider (LHC) are able to discover or set limits on the production of exotic particles with TeV-scale masses possessing values of electric and/or magnetic charge such that they appear as highly ionising particles (HIPs). In this paper the sensitivity of the LHC experiments to HIP production is discussed in detail. It is shown that a number of different detection methods are required to investigate as fully as possible the charge-mass range. These include direct detection as the HIPs pass through detectors and, in the case of magnetically charged objects, the so-called induction method with which monopoles which stop in accelerator and detector material could be observed. The benefit of using complementary approaches to HIP detection is discussed.

The XUV spectra of highly ionised molybdenum

International Nuclear Information System (INIS)

Mansfield, M.W.D.; Peacock, N.J.; Smith, C.C.; Hobby, M.G.; Cowan, R.D.

1978-01-01

The spectra of molybdenum ions produced in Tokamaks in the wavelength range 10-200 A have been reproduced in a plasma formed by laser beam irradiation of solid molybdenum targets. Lines from highly ionised stages of molybdenum (Mo XXX to Mo XXXII) have been distinguished by varying the laser beam intensity. Detailed analyses of the simpler ions, Mo XV (Ni-like), Mo XVI (Co-like), Mo XXXII (Na-like), and to a lesser extent Mo XXXI (Mg-like) and Mo XVII (Fe-like), have been achieved by comparison with ab initio calculations. A general interpretation of intermediate ion stages is also given but it is shown that most of these spectra are so complex, as a result of inner-subshell excitation, that detailed term-scheme analyses are nearly impossible. (author)

EDDIX--a database of ionisation double differential cross sections.

Science.gov (United States)

MacGibbon, J H; Emerson, S; Liamsuwan, T; Nikjoo, H

2011-02-01

The use of Monte Carlo track structure is a choice method in biophysical modelling and calculations. To precisely model 3D and 4D tracks, the cross section for the ionisation by an incoming ion, double differential in the outgoing electron energy and angle, is required. However, the double differential cross section cannot be theoretically modelled over the full range of parameters. To address this issue, a database of all available experimental data has been constructed. Currently, the database of Experimental Double Differential Ionisation Cross sections (EDDIX) contains over 1200 digitalised experimentally measured datasets from the 1960s to present date, covering all available ion species (hydrogen to uranium) and all available target species. Double differential cross sections are also presented with the aid of an eight parameter functions fitted to the cross sections. The parameters include projectile species and charge, target nuclear charge and atomic mass, projectile atomic mass and energy, electron energy and deflection angle. It is planned to freely distribute EDDIX and make it available to the radiation research community for use in the analytical and numerical modelling of track structure.

Single-stage accelerator mass spectrometer radiocarbon-interference identification and positive-ionisation characterisation

Energy Technology Data Exchange (ETDEWEB)

Wilcken, K.M., E-mail: klaus.wilcken@ansto.gov.au [Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, East Kilbride G75 0QF (United Kingdom); Freeman, S.P.H.T.; Xu, S.; Dougans, A. [Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, East Kilbride G75 0QF (United Kingdom)

2013-01-15

A single-stage accelerator mass spectrometer (SSAMS) is a good alternative to conventional spectrometers based on tandem electrostatic acceleration for radiocarbon measurement and permits experimentation with both negative and positive carbon ions. However, such {sup 14}C AMS of either polarity ions is limited by an interference. In the case of anion acceleration we have newly determined this to be summed {sup 13}C and {sup 16}O by improvising an additional Wien filter on our SSAMS deck. Also, {sup 14}C AMS might be improved by removing its dependency on negative-ionisation in a sputter ion source. This requires negative-ionisation of sample atoms elsewhere to suppress the {sup 14}N interference, which we accomplish by transmitting initially positive ions through a thin membrane. The ionisation dependence on ion-energy is found to be consistent with previous experimentation with vapours and thicker foils.

Dedicated Trigger for Highly Ionising Particles at ATLAS

CERN Document Server

Katre, Akshay; The ATLAS collaboration

2015-01-01

In 2012, a novel strategy was designed to detect signatures of Highly Ionising Particles (HIPs) such as magnetic monopoles, dyons or Q-balls with ATLAS. A dedicated trigger was developed and deployed for proton-proton collisions at a centre of mass energy of 8 TeV. It uses the Transition Radiation Tracker (TRT) system, applying an algorithm distinct from standard tracking ones. The high threshold (HT) readout capability of the TRT is used to distinguish HIPs from other background processes. The trigger requires significantly lower energy depositions in the electromagnetic calorimeters and is thereby capable of probing a larger range of HIP masses and charges. A description of the algorithm for this newly developed trigger is presented, along with a comparitive study of its performance during the 2012 data-taking period with respect to previous efforts.

Electron impact ionisation cross-sections of 2-heptanone

Science.gov (United States)

Vacher, J. R.; Blin-Simiand, N.; Jorand, F.; Pasquiers, S.

2005-01-01

The electron impact ionisation of 2-heptanone between 13 and 78 eV is studied using mass spectrometry. CH3C(O)CH2CH2CH2CH2CH3+ and fragment ions are produced with a total cross-section of 5 × 10-16 cm2 towards 50 eV. Two ions, identified as CH3CO+ (43 amu) and CH3C(OH)CH2+ (58 amu), contribute to about 60% of the total cross-section for electron energies above the ionisation threshold. The detected ions are identified using ab initio calculations. For E = 14 eV, the ion of 58 amu is the most abundant followed by an ion of 59 amu identified as being CH3C(OH)CH3+; they result from a bond cleavage with one or two H atom rearrangements. For E >= 48 eV, the ion of 43 amu is the most abundant; it results from an [alpha]-cleavage reaction in the molecular ion.

Basic radiation chemistry for the ionising energy treatment of food

International Nuclear Information System (INIS)

Moore, P.W.

1985-01-01

Before we can understand the chemistry involved in the irradiation of complex substances such as food we need to have some appreciation of the reactions involved and the products formed when ionising energy interacts with the simple substances such as water and dilute solutions. Reactions involving hydrated electrons, hydrogen atoms and hydroxyl radicals are examined and methods for minimising radiolytic effects in foods are discussed

Dedicated Trigger for Highly Ionising Particles at ATLAS

CERN Document Server

Katre, Akshay; The ATLAS collaboration

2015-01-01

In 2012, a novel strategy was designed to detect signatures of Highly Ionising Particles (HIPs) such as magnetic monopoles, dyons or Qballs with the ATLAS trigger system. With proton-proton collisions at a centre of mass enegy of 8 TeV, the trigger was designed to have unique properties as a tracker for HIPs. It uses only the Transition Radiation Tracker (TRT) system, applying an algorithm distinct from standard tracking ones. The unique high threshold readout capability of the TRT is used at the location where HIPs in the detector are looked for. In particular the number and the fraction of TRT high threshold hits is used to distinguish HIPs from background processes. The trigger requires significantly lower energy depositions in the electro-magnetic calorimeters as a seed unlike previously used trigger algorithms for such searches. Thus the new trigger is capable of probing a large range of HIP masses and charges. We will give a description of the algorithms for this newly developed trigger for HIP searches...

The work of the ILO in the field of protection of workers against ionising and non-ionising radiations

International Nuclear Information System (INIS)

Coppee, G.H.

1980-01-01

A chronological account since 1934 of the activities of the International Labour Organization (ILO) in the protection of workers against risks due to ionising and non-ionising radiations is given. Several ILO publication on safety standards and codes of practice for protection against mainly ionising radiation in various occupational situations are indicated. A more intensive study by the ILO on the protection of workers against non-ionising radiation was proposed for 1980-81. (UK)

Ionisation of L subshells of heavy atoms by deuteron collision

International Nuclear Information System (INIS)

Sokhi, R.S.; Crumpton, D.; Trautmann, D.

1989-01-01

L i subshell ionisation cross sections for 1.2-3.0 MeV deuteron impact on thin targets of W, Au, Pb and Bi have been measured experimentally. Measurements were made with the Birmingham University's 3MV Dynamitron accelerator and the cross sections were deduced from the emitted L X-rays. These cross sections and their ratios have been compared graphically with the ECPSSR and RHSCA models. The ECPSSR model underestimates the measured L 2 subshell cross sections but shows very good agreement with the L 3 subshell values. The RHSCA theory in general exhibits good agreement with the measured cross sections for the L 1 and L 2 subshells but overestimates the L 3 cross sections by up to 60%. (orig.)

Biomarkers specific to densely-ionising (high LET) radiations

International Nuclear Information System (INIS)

Brenner, D.J.; Okladnikova, N.; Hande, P.; Burak, L.; Geard, C.R.; Azizova, T.

2001-01-01

There have been several suggestions of biomarkers that are specific to high LET radiation. Such a biomarker could significantly increase the power of epidemiological studies of individuals exposed to densely-ionising radiations such as alpha particles (e.g. radon, plutonium workers, individuals exposed to depleted uranium) or neutrons (e.g. radiation workers, airline personnel). We discuss here a potentially powerful high LET biomarker (the H value) which is the ratio of induced inter-chromosomal aberrations to intra-arm aberrations. Both theoretical and experimental studies have suggested that this ratio should differ by a factor of about three between high LET radiation and any other likely clastogen, and will yield more discrimination than the previously suggested F value (ratio of inter-chromosomal aberrations to intra-chromosomal inter-arm aberrations). Evidence of the long-term stability of such chromosomal biomarkers has also been generated. Because these stable intra-arm and inter-chromosomal aberrations are (1) frequent and (2) measurable at long times after exposure, this H value appears to be a practical biomarker of high LET exposure, and several in vitro studies have confirmed the approach for unstable aberrations. The approach is currently being tested in a population of Russian radiation workers exposed several decades ago to high- or low LET radiation. (author)

Immunosuppression by non-ionising and ionising radiation - are there similarities?

International Nuclear Information System (INIS)

Reeves, V.

2003-01-01

Solar UV radiation, the ubiqitous environmental non-ionising radiation, initiates its immunomodulating effects almost entirely in the skin. In direct contrast, ionising radiation penetrates much more efficiently, and has a multitude of internal targets throughout the body. As a consequence, the mechanisms underlying UV-induced immunosuppression have been more readily characterised, whereas surprisingly little is known about immunosuppression resulting from ionising radiation. Photoimmunological studies in mice during the past 20-30 years have established the action spectrum for UV-induced immunosuppression, implicating the UVB waveband, 290-320 nm. Controversy rages over the immunosuppressive potential of the UVA waveband, 320-400 nm, but we demonstrate that environmentally relevant doses of UVA not only are immunologically innocuous, but provide protection against UVB-immunosuppression. Increasingly larger UVA exposures increasingly immunosuppress mice. The UVA immunoprotective effect is strongly dependent on the induction of a cutaneous redox-regulated enzyme, haem oxygenase (heat shock protein 32) that is known to protect cells from oxidative stress, and it is consistent that a number of exogenous antioxidants (vitamin E, vitamin C, green tea polyphenols, isoflavones) can protect effectively from photoimmuno-suppression. Thus the UV-immunosuppressed state is promoted by oxidative damage and depletion of endogenous antioxidant molecules. It is also associated with cutaneous cytokine derangements, such that Th-2 cytokines (IL-4, IL-10) are increased at the expense of Th-1 cytokines (IFN-gamma, IL-12), and with histamine and inflammatory prostaglandin activity. In contrast, immunoprotective UVA irradiation protects the cutaneous cytokine array, inhibits IL-10 upregulation and increases IFN-gamma and IL-12 expression. On the other hand, while ionising radiation is known to cause immunosuppression, large doses target the bone marrow and haemopoiesis lethally and

Correlation effects in electron-atom collisions

International Nuclear Information System (INIS)

Water, W. van de.

1981-01-01

This thesis deals with correlation effects occurring in the outer region of configuration space after an ionising collision. The motion of both escaping electrons in the external region is then fully determined by the long-range Coulomb forces. Firstly the threshold ionisation of hydrogen-like targets is studied. In that case two slow electrons attempt to escape from the Coulomb attraction of the residual ion. Secondly ionising collisions, with the formation of an autoionising state as an intermediate step, are considered. Such an autoionising state is in fact a quasi bound state of the neutral atom which lies imbedded in the ionisation continuum. The state decays after a certain lifetime by emission of an electron. Of all states to be formed in the reaction region only the autoionising state(s) under consideration is then relevant for this type of ionisation process. The energy positions of autoionising states usually are such that the electron to be ionised is ejected with a rather large velocity. The correlation in the outer region of configuration space then consists of the interaction of a fast ejected electron and, in case of threshold excitation of the autoionising state, a slow scattered electron. (Auth.)

A Discussion about Ionising and Non-Ionising Radiation and the Critical Issue of Mobile Phones

Science.gov (United States)

Kontomaris, Stylianos-Vasileios; Malamou, Anna

2018-01-01

Electromagnetic radiation is one of the most important issues affecting peoples' lives today. The misunderstanding of students and the general population of the effects of electromagnetic radiation is a problem which must be eliminated. Thus, a discussion about ionising and non-ionising radiation focusing on the crucial issue of radiation emitted…

Food ionisation. Realities and perspectives; L'ionisation alimentaire. Realites et perspectives

Energy Technology Data Exchange (ETDEWEB)

Bonnet, G

1994-06-01

The ionisation of food is a treatment using a certain type of energy. the radiations used in the industrial treatments are limited to three sources. The gamma radiations, the x radiations and the electrons beams emitted with accelerators. The physical treatments by ionizing radiations have for aim to cleanse and to increase the conservation time of food. Now, the applications in agriculture and food industry, are still marginal. The industrial using ionisation are these ones that did not find any alternative decontamination method. The barriers are more scientific or technical or economical than a question of regulation or behaviour. (N.C.)

Study of total ionization by {alpha} particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature; Etude de l'ionisation totale par les paricules {alpha}, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature

Energy Technology Data Exchange (ETDEWEB)

Bristeau, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

Experiments have been carried out on the total ionization by alpha particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature. Using a different experimental method, the results for the mean ionization energy at 300 K given by Jesse in 1953 have been confirmed to within 1 per cent. It is established that in pure gases the mean energy W required to form a pair of ions remains constant as the temperature varies from 77 to 300 K. It is shown that there is a temperature effect for W in binary gas mixtures of the type A-B containing meta-stable atoms A{sup *} and an 'impurity' B. A systematic study is made of the change {delta}W in W as a function of the temperature and of the B 'impurity' concentration in the mixtures Ne - Ar, Ne - Kr, Ne - H{sub 2}, Ne - N{sub 2}, Ne - CH{sub 4} and He - Ar. Experiments have been carried out on a ternary gas mixture of the type A - B - C, where C is a second ionizable 'impurity' added to the binary mixture A - B; they show the existence of excited atoms B{sup *} formed from the 'impurity' B. Finally, it is shown that the amount of metastable atoms formed in a pure gas must be very close to the number N{sub 0} of ion pairs, and that there must exist a correlation between the number N{sub 0} of ion pairs and the number {approx_equal} N{sub 0} of metastable atoms created in the pure rare gases. (author) [French] On realise des experiences sur l'ionisation totale par les particules alpha, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature. Avec une methode experimentale differente, on retrouve a mieux que 1 pour cent pres les valeurs de l'energie moyenne d'ionisation que JESSE a obtenues en 1953 et a 300 K. On etablit que dans les gaz purs, l'energie moyenne W pour creer une paire d'ions demeure constante, quand la temperature varie entre 77 et 300 K. On met en evidence un effet de temperature sur W, dans les melanges gazeux binaires du type

Sensitivity of gaseous xenon ionisation chambers (1961); Sensibilite des chambres d'ionisation a xenon gazeux (1961)

Energy Technology Data Exchange (ETDEWEB)

Schuhl, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

It seems advantageous to fill an ionization chamber with xenon gas when this chamber is used for measuring a low intensity and high energy electron or positron beam, or monitoring a gamma beam. In the study of 5 to 50 MeV electrons, xenon allows for the ionization chamber yield, an improvement of a factor 4,5. (author) [French] Il apparait interessant d'utiliser du xenon comme gaz dans une chambre d'ionisation destinee a mesurer un faisceau d'electrons ou de positons de faible intensite et de grande energie ou pour monitorer un faisceau de gamma. Dans les etudes des electrons de 5 a 50 MeV, le xenon permet de gagner un facteur 4,5 sur l'air pour la sensibilite d'une chambre d'ionisation. (auteur)

Atomic theories

CERN Document Server

Loring, FH

2014-01-01

Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

Genetic effects of ionising radiation

International Nuclear Information System (INIS)

Saunders, P.

1981-01-01

The mutagenic effects of ionising radiation on germ cells with resulting genetic abnormalities in subsequent generations, are considered. Having examined a simple model to explain the interaction of ionising radiation with genetic material and discussed its limitations, the methods whereby mutations are transmitted are discussed. Methods of estimating genetic risks and the results of such studies are examined. (U.K.)

Photoionisation detection of single 87Rb-atoms using channel electron multipliers

International Nuclear Information System (INIS)

Henkel, Florian Alexander

2011-01-01

Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p ion =0.991 within an ionisation time of t ion =386 ns is achieved for a single 87 Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of η atom =0.991 within a detection time of t det =415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral 87 Rb-atoms via photoionisation detection with an estimated detection efficiency η=0.982 and a detection time of t tot = 802 ns. Although initially developed for single 87 Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any atomic or molecular species. As efficient

Dosimetry with tissue-equivalent ionisation chambers in fast neutron fields for biomedical applications

International Nuclear Information System (INIS)

Zoetelief, J.; Broerse, J.J.

1983-01-01

The use of calibrated tissue-equivalent (TE) ionisation chambers is commonly considered to be the most practical method for total absorbed dose determinations in mixed neutron-photon fields for biomedical applications. The total absorbed dose can be derived from the charge produced within the cavity of an ionisation chamber employing a number of physical parameters. To arrive at the charge produced in the cavity several correction factors have to be introduced which are related to the operational characteristics of the chambers. Information on the operational characteristics of four TE ionisation chambers is presented in relation to ion collection, density and composition of gas in the cavity, wall thickness and effective point of measurement. In addition, some recent results from an ionisation chamber operated at high gas pressures are presented. The total absorbed doses derived from TE ionisation chambers show agreement within the uncertainty limits with results from other independent dosimetry methods, i.e., differential fluence measurements and a TE calorimeter. Conscientious experimentation and a common data base can provide dosimetry results with TE ionisation chambers with variations of less than +-2%. (author)

Characterisation of tryptic peptides of phosphorylated tyrosine hydroxylase by high-pressure liquid chromatography electrospray ionisation mass spectrometry

International Nuclear Information System (INIS)

Graham, Mark E.; Dickson, Phillip W.; Dunkley, Peter R.; Nagy-Felsobuki, Ellak I. von

2005-01-01

Tyrosine hydroxylase (TH) is involved in the biosynthesis of catecholamines and is activated by phosphorylation. Phosphorylated TH was analysed using high-pressure liquid chromatography combined with electrospray mass spectrometry (HPLC ESI-MS). Two mass scanning methods were used to detect tryptic cleavage products of TH. In the positive electrospray ionisation mode (ESI+), the peptides that contain the phosphorylation sites of TH were identified. In the alternative method, a phosphopeptide was detected in the negative electrospray ionisation mode (ESI-) using single ion monitoring in combination with a sequential ESI+ switching experiment. A raised baseline interfered with detection of hydrophilic peptides in ESI-, with the signal-to-noise ratio indicating that the method was operating near the limit of detection for a conventional electrospray source. The switching method improved the certainty of identification of phosphopeptides

Food ionisation. Realities and perspectives; L'ionisation alimentaire. Realites et perspectives

Energy Technology Data Exchange (ETDEWEB)

Bonnet, G

1994-06-01

The ionisation of food is a treatment using a certain type of energy. the radiations used in the industrial treatments are limited to three sources. The gamma radiations, the x radiations and the electrons beams emitted with accelerators. The physical treatments by ionizing radiations have for aim to cleanse and to increase the conservation time of food. Now, the applications in agriculture and food industry, are still marginal. The industrial using ionisation are these ones that did not find any alternative decontamination method. The barriers are more scientific or technical or economical than a question of regulation or behaviour. (N.C.)

Photoionisation detection of single {sup 87}Rb-atoms using channel electron multipliers

Energy Technology Data Exchange (ETDEWEB)

Henkel, Florian Alexander

2011-09-02

Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p{sub ion}=0.991 within an ionisation time of t{sub ion}=386 ns is achieved for a single {sup 87}Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of {eta}{sub atom}=0.991 within a detection time of t{sub det}=415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral {sup 87}Rb-atoms via photoionisation detection with an estimated detection efficiency {eta}=0.982 and a detection time of t{sub tot} = 802 ns. Although initially developed for single {sup 87}Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any

International Atomic Energy Agency Regional Workshop on Commercialisation of ionising energy treatment of food: proceedings

International Nuclear Information System (INIS)

Wills, P.; Toner, B.

1985-01-01

The global need to ensure adequate food supplies places a demand on new technologies and techniques to improve yields and preservation of food by eliminating or reducing bacterial degradation and infestation of raw or processed foods. The use of ionising radiation in food processing also has potential to alleviate certain food-borne diseases which cause serious threats to the health of people in many countries

Theoretical methods for the calculation of the multiphoton ionisation cross-section of atoms and molecules

International Nuclear Information System (INIS)

Moccia, R.

1991-01-01

Some of the available theoretical methods to compute the two-photon ionisation cross-section of many-electron systems are reviewed. In particular the problems concerning the computation of (i) reliable approximations for the transition matrix elements and the excitation energies; and (ii) accurate results pertaining to the electronic continuum by the use of L 2 basis functions are considered. (author). 29 refs., 6 figs., 1 tab

Kinematically complete study on electron impact ionisation of aligned hydrogen molecules

Energy Technology Data Exchange (ETDEWEB)

Senftleben, Arne

2009-10-28

Within the work presented here, single ionisation of spatially aligned hydrogen molecules by 200 eV electrons was studied in a kinematically complete experiment. For the first time, a comprehensive set of fully differential cross sections (FDCS) was obtained for this process on a molecular target. The direction of the internuclear axis was derived from the fragment emission of post-collision dissociation of the residual H{sub 2}{sup +} ion. Therefore, a protonic fragment was detected in coincidence with the two final-state electrons using a dedicated reaction microscope and sophisticated data analysis. For direct ionisation into the ionic ground state, existing theoretical cross sections for aligned molecules were tested. Additionally, we observed molecular frame angular distributions of Auger electrons emitted through dissociative autoionisation of H{sub 2}. Earlier findings of kinematically incomplete experiments were reproduced, but the FDCS reveal structures so far unknown. Furthermore, for random alignment, differential cross sections at two distinct values of the mean internuclear distance were obtained, providing new arguments in the current discussion on the nature of discrepancies observed between atomic and molecular collisions. (orig.)

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Science.gov (United States)

Heays, A. N.; Bosman, A. D.; van Dishoeck, E. F.

2017-06-01

A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium

Impact assessment of ionising radiation on wildlife

International Nuclear Information System (INIS)

Copplestone, D.; Bielby, S.; Jones, S.

2001-01-01

This R and D project was commissioned by the Environment Agency and English Nature in January 2001 to provide up-to-date information on the impacts of ionising radiation on wildlife, upon which a robust assessment approach may be developed. This approach will also feed into the European Commission funded project 'Framework for Assessment of Environmental Impact' (FASSET), due to complete in October 2003. This report describes the behaviour and transport of radionuclides in the environment, considers the impact of ionising radiation on wildlife, and makes recommendations on an approach for the impact assessment of ionising radiation on wildlife for England and Wales. The assessment approach focuses on three ecosystems representative of those considered potentially most at risk from the impact of authorised radioactive discharges, namely a coastal grassland (terrestrial ecosystem); estuarine and freshwater ecosystems. The likely scale of the impact on wildlife is also assessed in light of a preliminary analysis based on this assessment approach. The aims of the report are: to summarise the latest research on the behaviour, transfer and impact of ionising radiation effects on wildlife; an outline and review of the relevant European and national legislation which has impacts on the requirements for assessments of the impact of ionising radiation on wildlife in the UK; to consider the role of regulatory bodies in assessing the impact of ionising radiation on wildlife with respect to England and Wales; to make recommendations on the relative biological effectiveness of different types of radiation with respect to wildlife; and to recommend an approach to assess the impacts to wildlife from ionising radiation from authorised discharges in England and Wales, with spreadsheets to support the methodology. The report demonstrates the behaviour and transfer of radionuclides in a number of different ecosystem types. Particular emphasis is placed on exposure pathways in those

Double spike methodology for uranium determination by thermal ionisation mass spectrometry: separation and purification of 234U

International Nuclear Information System (INIS)

Shah, P.M.; Saxena, M.K.; Sanjai Kumar; Aggarwal, S.K.; Jain, H.C.

1995-01-01

With an objective to prepare double spike of 233 U+ 234 U for determination of uranium concentration by Isotopic Dilution Thermal Ionisation Mass Spectrometry (ID-TIMS), 234 U was separated and purified from aged 238 Pu sample (15 years old) using several ion exchange and solvent extraction procedures. Final product containing 95% and 5% alpha activities of 234 and 238 Pu, respectively, which translates into 99.998 atom% of 234 U and 0.002 atom% of 238 Pu was found suitable for double spike. (author). 1 ref

Impact assessment of ionising radiation in wildlife

International Nuclear Information System (INIS)

2001-01-01

This R and D project was commissioned by the Environment Agency and English Nature in January 2001 to provide up-to-date information on ionising radiation impact to wildlife, upon which a robust assessment approach may be developed. The methodology will provide an interim approach, whilst awaiting the outcome of the European Commission funded project 'Framework for Assessment of Environmental Impact' (FASSET) due to end in October 2003. The aims of the report were: to summarise the latest research on the behaviour, transfer and impact of ionising radiation effects on wildlife; to outline and review relevant European Directives which have impacted on the requirements to assess the impact to wildlife from ionising radiation in the UK; to consider the role of regulatory bodies in assessing the impact of ionising radiation on wildlife with respect to England and Wales; to make recommendations on the relative biological effectiveness of different types of radiation with respect to wildlife; and to recommend an approach with which to assess the 'scale of risk' to wildlife from the effects of ionising radiation, with spreadsheets to support the methodology. The report describes the behaviour and transfer of radionuclides in a number of different ecosystem types. Particular emphasis is placed on those ecosystems most likely to be impacted by the authorised discharges of radioactivity within the UK. As there is no international consensus on the approach to be taken to assess the impact of ionising radiation on wildlife, some countries have adopted their own legislation. The report evaluates these regulatory frameworks and describe the current UK position

Electron impact ionisation cross sections of iron oxides

Science.gov (United States)

Huber, Stefan E.; Mauracher, Andreas; Sukuba, Ivan; Urban, Jan; Maihom, Thana; Probst, Michael

2017-12-01

We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10-16 cm2 located at 59-72 eV and 5.06 to 14.32 × 10-16 cm2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80308-2.

Nucleation in an ultra low ionisation environment

DEFF Research Database (Denmark)

Enghoff, Martin Andreas Bødker

in aerosol nucleation. By exposing a controlled volume of air to varying levels of ionising radiation, and with the minimum ionisation level vastly reduced compared to normal surface laboratory conditions, we have provided both a validation of earlier studies of ion-induced nucleation and extended...

Effects of small doses of ionising radiation

International Nuclear Information System (INIS)

Doll, R.

1998-01-01

Uncertainty remains about the quantitative effects of doses of ionising radiation less than 0.2 Sv. Estimates of hereditary effects, based on the atomic bomb survivors, suggest that the mutation doubling dose is about 2 Sv for acute low LET radiation, but the confidence limits are wide. The idea that paternal gonadal irradiation might explain the Seascale cluster of childhood leukaemia has been disproved. Fetal irradiation may lead to a reduction in IQ and an increase in seizures in childhood proportional to dose. Estimates that doses to a whole population cause a risk of cancer proportional to dose, with 0.1 Sv given acutely causing a risk of 1%, will need to be modified as more information is obtained, but the idea that there is a threshold for risk above this level is not supported by observations on the irradiated fetus or the effect of fallout. The idea, based on ecological observations, that small doses protect against the development of cancer is refuted by the effect of radon in houses. New observations on the atomic bomb survivors have raised afresh the possibility that small doses may also have other somatic effects. (author)

Observation of $\\pi^- K^+$ and $\\pi^+ K^-$ atoms

CERN Document Server

Adeva, B; The PS212 collaboration; Allkofer, Y.; Amsler, C.; Anania, A.; Aogaki, S.; Benelli, A.; Brekhovskikh, V.; Cechak, T.; Chiba, M.; Chliapnikov, P.; Doskarova, P.; Drijard, D.; Dudarev, A.; Dumitriu, D.; Fluerasu, D.; Gorin, A.; Gorchakov, O.; Gritsay, K.; Guaraldo, C.; Gugiu, M.; Hansroul, M.; Hons, Z.; Horikawa, S.; Iwashita, Y.; Karpukhin, V.; Kluson, J.; Kobayashi, M.; Kruglov, V.; Kruglova, L.; Kulikov, A.; Kulish, E.; Kuptsov, A.; Lamberto, A.; Lanaro, A.; Lednicky, R.; Marinas, C.; Martincik, J.; Nikitin, M.; Okada, K.; Olchevskii, V.; Pentia, M.; Penzo, A.; Plo, M.; Prusa, P.; Rappazzo, G.; Vidal, A.Romero; Ryazantsev, A.; Rykalin, V.; Saborido, J.; Sidorov, A.; Smolik, J.; Takeutchi, F.; Tauscher, L.; Trojek, T.; Trusov, S.; Urban, T.; Vrba, T.; Yazkov, V.; Yoshimura, Y.; Zhabitsky, M.; Zrelov, P.

2016-01-01

The observation of hydrogen-like $\\pi K$ atoms, consisting of $\\pi^- K^+$ or $\\pi^+ K^-$ mesons, is presented. The atoms have been produced by 24 GeV/$c$ protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. The breakup (ionisation) of $\\pi K$ atoms in the same targets yields characteristic $\\pi K$ pairs, called ``atomic pairs'', with small relative momenta in the pair centre-of-mass system. The upgraded DIRAC experiment has observed $349\\pm62$ such atomic $\\pi K$ pairs, corresponding to a signal of 5.6 standard deviations.

Highly excited atoms

International Nuclear Information System (INIS)

Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

1981-01-01

Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

Working Group on Ionising Radiations. Report 1987-88

International Nuclear Information System (INIS)

1989-01-01

The programme of work for 1987/88 by the Working Group on Ionising Radiation, Health and Safety Commision in February 1988, included the main topics of continuing interest and concern in relation to ionising radiations in general and the Ionising Radiations Regulations 1985 (IRR 85) (Ref 1) in particular. These were: emergency dose limitation, occupational dose limitation, practical experience of the principle of keeping doses as low as reasonably practicable, experience of the regulatory requirements in respect of internal dosimetry and the need for a standing advisory committee on ionising radiations. Calibration of radiotherapy equipment was also considered as a matter of principle following a specific incident involving cancer patients. This report of progress during the first year summarises the Group's opinions on each topic and gives recommendations. (author)

Ionising radiation - physical and biological effects

International Nuclear Information System (INIS)

Holter, Oe.; Ingebretsen, F.; Parr, H.

1979-01-01

The physics of ionising radiation is briefly presented. The effects of ionising radiation on biological cells, cell repair and radiosensitivity are briefly treated, where after the effects on man and mammals are discussed and related to radiation doses. Dose limits are briefly discussed. The genetic effects are discussed separately. Radioecology is also briefly treated and a table of radionuclides deriving from reactors, and their radiation is given. (JIW)

Ionised Jets Associated With Massive Young Stellar Objects

Science.gov (United States)

Purser, Simon John Derek

2017-09-01

This thesis focuses on the phenomena of ionised jets associated with massive young stellar objects. Firstly a study was conducted with the aim to establish a statistical sample of such objects. Radio observations towards a sample of 49 MYSOs resulted in the detection of 28 objects classified as ionised jets. The jets’ radio luminosities scaled with their MYSOs’ bolometric luminosities in the same way as for low-mass examples. This infers that the jet launching and collimation mechanisms of high-mass jets are very similar to that in their low-mass counterparts and they are ejected for the last ≤65000 yr of the MYSO phase. Interestingly non-thermal emission was regularly detected towards spatially distinct radio lobes (associated with ˜50% of the jets), suggesting the presence of synchrotron emission and therefore, magnetic fields. With an average spectral index of ¯α=‑0. 55 (indicative of the 1st order Fermi acceleration mechanism) it is concluded these lobes are the result of shocks in the jets’ stream. My second science chapter is a study of radio variability, precession and proper motions towards a subset of objects from the first chapter. Over a two year time period, no significant variability and only one example of proper motion (1800±600 km s‑1) was detected. Precession was found to be commonplace however and if it arises as the result of binary interactions, we infer orbital radii between 30 and 1800 au for the binary companions. Lastly, high-resolution, VLA observations at C and Q-bands were analysed to extend the known sample of MYSOs harbouring ionised jets into the northern hemisphere. Only 3 radio sources were detected possessing jet-like characteristics towards the work’s sub-sample of 8 IRDCs containing 44 mm-cores (in our field of view), highlighting the radio-quiet (≳30μJy) nature of this early phase in massive star formation. Towards the RMS survey derived sample of 48 MYSOs, a total of 38 radio sources with jet

The ionisation balance of C0 to C+4

International Nuclear Information System (INIS)

Nussbaumer, H.; Storey, P.J.

1975-01-01

The ionisation balance for the ions C 0 -C +4 has been calculated for 10 8 -3 ] 12 and 2 x 10 4 K 5 K. The presence of metastable terms is included in the calculation of the collisional dielectronic recombination and ionisation coefficients. The influence of the observed solar radiation field on the ionisation balance is investigated. Changes in that field do strongly influence the results. (orig.) [de

Food ionisation. Realities and perspectives

International Nuclear Information System (INIS)

Bonnet, G.

1994-06-01

The ionisation of food is a treatment using a certain type of energy. the radiations used in the industrial treatments are limited to three sources. The gamma radiations, the x radiations and the electrons beams emitted with accelerators. The physical treatments by ionizing radiations have for aim to cleanse and to increase the conservation time of food. Now, the applications in agriculture and food industry, are still marginal. The industrial using ionisation are these ones that did not find any alternative decontamination method. The barriers are more scientific or technical or economical than a question of regulation or behaviour. (N.C.)

The ionisation loss of relativistic charged particles in thin gas samples and its use for particle identification. I

International Nuclear Information System (INIS)

Cobb, J.H.; Allison, W.W.M.; Bunch, J.N.

1976-01-01

A brief review shows a significant discrepancy between available data and theoretical predictions on the ionisation loss of charged particles in thin gas-filled proportional counters. The discrepancy related both to the increase of the most probable loss at relativistic velocities (relativistic rise) and to the spectrum of such losses at a given velocity (the Landau distribution). The origin of this relativistic rise is discussed in simple terms and related to the phenomena of transition radiation and Cherenkov radiation. It is shown that the failure of the prediction is due to the small number of ionising collisions in a gas. This problem is overcome by using a Monte Carlo method rather than a continuous integral over the spectrum of single collision processes. A specific mode of the atomic form factors is used with a modified Born approximation to yield the differential cross sections needed for the calculation. The new predictions give improved agreement with experiment and are used to investigate the problem of identifying particles of known momenta in the relativistic region. It is shown that by measuring the ionisation loss of each particle several hundred times over 5m or more, kaon, pion and proton separation with good confidence level may be achieved. Many gases are considered and a comparison is made. The results are also compared with the velocity resolution achievable by measuring primary ionisation. (Auth.)

Metabolic changes in broiler chickens exposed to low dose of ionising radiation

International Nuclear Information System (INIS)

Danova, D.; Kafka, I.; Kalenicova, Z.; Petrovova, E.; Toropila, M.

2008-01-01

In our experiment broiler chickens, 28-day old, were exposed to single whole- body dose 3 Gy of ionising radiation in time gap 3., 7., 14. and 21 day. We applied zinc to organism of chicks after irradiation. We observed changes of concentrations of cholesterol and glucose in blood serum. From obtained results it is evident that despite relative high resistance of poultry to irradiation, it reacts strongly to ionising radiation even at laboratory levels. (authors)

Ionised gas kinematics in bipolar H II regions

Science.gov (United States)

Dalgleish, Hannah S.; Longmore, Steven N.; Peters, Thomas; Henshaw, Jonathan D.; Veitch-Michaelis, Joshua L.; Urquhart, James S.

2018-05-01

Stellar feedback plays a fundamental role in shaping the evolution of galaxies. Here we explore the use of ionised gas kinematics in young, bipolar H II regions as a probe of early feedback in these star-forming environments. We have undertaken a multi-wavelength study of a young, bipolar H II region in the Galactic disc, G316.81-0.06, which lies at the centre of a massive (˜103 M⊙) infrared-dark cloud filament. It is still accreting molecular gas as well as driving a ˜0.2 pc ionised gas outflow perpendicular to the filament. Intriguingly, we observe a large velocity gradient (47.81 ± 3.21 km s-1 pc-1) across the ionised gas in a direction perpendicular to the outflow. This kinematic signature of the ionised gas shows a reasonable correspondence with the simulations of young H II regions. Based on a qualitative comparison between our observations and these simulations, we put forward a possible explanation for the velocity gradients observed in G316.81-0.06. If the velocity gradient perpendicular to the outflow is caused by rotation of the ionised gas, then we infer that this rotation is a direct result of the initial net angular momentum in the natal molecular cloud. If this explanation is correct, this kinematic signature should be common in other young (bipolar) H II regions. We suggest that further quantitative analysis of the ionised gas kinematics of young H II regions, combined with additional simulations, should improve our understanding of feedback at these early stages.

Exploring the Powerful Ionised Wind in the Seyfert Galaxy PG1211+143

Science.gov (United States)

Pounds, Ken

2013-10-01

Highly-ionised high-speed winds in AGN (UFOs) were first detected with XMM-Newton a decade ago, and are now established as a key factor in the study of SMBH accretion, and in the growth and metal enrichment of their host galaxies. However, information on the ionisation and dynamical structure, and the ultimate fate of UFOs remains very limited. We request a 600ks extended XMM-Newton study of the prototype UFO PG1211+143 in AO-13, to obtain high quality EPIC and RGS spectra, to map the flow structure and variability, while seeking evidence for the anticipated interaction with the ISM and possible conversion of the energetic wind to a momentum-driven flow.

A metastable helium trap for atomic collision physics

International Nuclear Information System (INIS)

Colla, M.; Gulley, R.; Uhlmann, L.; Hoogerland, M.D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Full text: Metastable helium in the 2 3 S state is an important species for atom optics and atomic collision physics. Because of its large internal energy (20eV), long lifetime (∼8000s) and large collision cross section for a range of processes, metastable helium plays an important role in atmospheric physics, plasma discharges and gas laser physics. We have embarked on a program of studies on atom-atom and electron-atom collision processes involving cold metastable helium. We confine metastable helium atoms in a magneto-optic trap (MOT), which is loaded by a transversely collimated, slowed and 2-D focussed atomic beam. We employ diode laser tuned to the 1083 nm (2 3 S 1 - 2 3 P2 1 ) transition to generate laser cooling forces in both the loading beam and the trap. Approximately 10 million helium atoms are trapped at temperatures of ∼ 1mK. We use phase modulation spectroscopy to measure the trapped atomic density. The cold, trapped atoms can collide to produce either atomic He + or molecular He 2 + ions by Penning Ionisation (PI) or Associative Ionisation (AI). The rate of formation of these ions is dependant upon the detuning of the trapping laser from resonance. A further laser can be used to connect the 2 3 S 1 state to another higher lying excited state, and variation of the probe laser detuning used to measure interatomic collision potential. Electron-atom collision processes are studied using a monochromatic electron beam with a well defined spatial current distribution. The total trap loss due to electron collisions is measured as a function of electron energy. Results will be presented for these atomic collision physics measurements involving cold, trapped metastable helium atoms. Copyright (1999) Australian Optical Society

The Belfast atomic data bank, recommended data, and the opacity project data base

International Nuclear Information System (INIS)

Berrington, K.A.; Kingston, A.E.; Sawey, P.M.J.

1991-01-01

The Belfast Atomic Data Bank holds data for the excitation and ionisation of atoms and ions by electrons and photons, and provides recommended data; electron excitation data recommended at regular Atomic Data Workshops is summarised. Photoabsorption data for all elements up to Fe have been calculated in the international Opacity Project, and a summary is given of the atomic data expected from the Project

Beam experiments with state selected Ne (3P0, 3P2) metastable atoms

International Nuclear Information System (INIS)

Verheijen, M.J.

1984-01-01

Metastable rare gas atoms play an important role in all types of plasmas and gas discharges, e.g. in fluorescent lamps and in laser discharges (helium-neon laser or excimer lasers). In this thesis, the metastable states of NeI are studied. First, the theory of excited neon atoms and diatomic molecules is introduced, as well as Penning ionisation. Next, some experimental facilities are described (e.g. the dye laser system). With these instruments, natural lifetime measurements of the 2p fine structure states of NeI are carried out. Results are reported. Finally, total Penning ionisation cross sections are calculated using the optical potential model. (Auth.)

The electrical charging of inactive aerosols in high ionised atmosphere, the electrical charging of artificial beta radioactive aerosols; Le processus de charge electrique: des aerosols non radioactifs en milieu fortement ionise, des aerosols radioactifs artificiels emetteurs beta

Energy Technology Data Exchange (ETDEWEB)

Gensdarmes, F

2000-07-01

The electrical properties of aerosols greatly influence their transport and deposition in a containment. In a bipolar ionic atmosphere, a neutral electric charge on aerosols is commonly assumed. However, many studies report a different charge distribution in some situations, like highly ionised atmosphere or in the case of radioactive aerosols. Such situations could arise from a hypothetical accident in a nuclear power plant. Within the framework of safety studies which are carried out at IPSN, our aims were the study of electrical properties of aerosols in highly ionised atmosphere, and the study of artificial radioactive aerosols, in order to suggest experimental validation of available theories. For this purpose, we designed an experimental device that allows us to measure non-radioactive aerosol charge distribution under high gamma irradiation, up to 10{sup 4} Gy/h. With our experimental device we also studied the properties of small ions in the medium. Our results show a variation of the charge distribution in highly ionised atmosphere. The charge increases with the dose of gamma ray. We have related this variation with the one of the small ions in the gases, according to theoretical prediction. However, the model overestimates slightly our experimental results. In the case of the radioactive aerosols, we have designed an original experimental device, which allows us to study the charge distribution of a {sup 137}Cs aerosol. Our results show that the electric charging of such aerosols is strongly dependent on evolution parameters in a containment. So, our results underline a great enhancement of self-charging of particles which are sampled in a confined medium. Our results are qualitatively in agreement with the theoretical model; nevertheless the latter underestimates appreciably the self-charging, owing to the fact that wall effects are not taken into account. (author)

Health Service use of ionising radiations: Guidance

International Nuclear Information System (INIS)

1995-01-01

This booklet gives outline guidance on the use of ionising radiations in the Health Service in the United Kingdom. Extensive reference is made to documents where more detailed information may be found. The guidance covers general advice on the medical use of ionising radiations, statutory requirements, and guidance on selected Health Service issues such as patient identification procedures, information management systems, deviations from prescribed radiation dose, imaging and radiotherapy. (57 references) (U.K.)

International bulletin on atomic and molecular data for fusion. No. 25

International Nuclear Information System (INIS)

Katsonis, K.

1984-06-01

This bulletin deals with atomic and molecular data for fusion. A bibliography for the most recent data presented in the document is provided. Work in progress is also briefly reported (Collision strengths and recombination coefficients for ions of C,N,O; Reactions between ions and atomic hydrogen; Cross sections for electron impact ionisation of Ne + , Ti + and Ni + ions)

Ionising radiation

International Nuclear Information System (INIS)

Anon.

1982-01-01

The law covering ionising radiation in Luxembourg is summarised under the headings: introduction (the outline law of 25 March 1963, and the Grand-Ducal Decree of 8 February 1967); the control of establishments (the authorisation procedure; emergency measures, suspension and withdrawal of the authorisation; alterations to the establishment); the importation, distribution and transit of radioactive substances; the transport of radioactive substances; the protection and safety of the population as a whole; sanctions; international conventions. (U.K.)

Simulation and measurements of the response of an air ionisation chamber exposed to a mixed high-energy radiation field

International Nuclear Information System (INIS)

Vincke, H.; Forkel-Wirth, D.; Perrin, D.; Theis, C.

2005-01-01

CERN's radiation protection group operates a network of simple and robust ionisation chambers that are installed inside CERN's accelerator tunnels. These ionisation chambers are used for the remote reading of ambient dose rate equivalents inside the machines during beam-off periods. This Radiation Protection Monitor for dose rates due to Induced Radioactivity ('PMI', trade name: PTW, Type 34031) is a non-confined air ionisation plastic chamber which is operated under atmospheric pressure. Besides its current field of operation it is planned to extend the use of this detector in the Large Hadron Collider to measure radiation under beam operation conditions to obtain an indication of the machine performance. Until now, studies of the PMI detector have been limited to the response to photons. In order to evaluate its response to other radiation components, this chamber type was tested at CERF, the high-energy reference field facility at CERN. Six PMI detectors were installed around a copper target being irradiated by a mixed hadron beam with a momentum of 120 GeV c -1 . Each of the chosen detector positions was defined by a different radiation field, varying in type and energy of the incident particles. For all positions, detailed measurements and FLUKA simulations of the detector response were performed. This paper presents the promising comparison between the measurements and simulations and analyses the influence of the different particle types on the resulting detector response. (authors)

Contribution to the study and use of ionisation chambers for nuclear reactor control (1965); Contribution a l'etude et a l'utilisation des chambres d'ionisation pour le controle des reacteurs nucleaires (1965)

Energy Technology Data Exchange (ETDEWEB)

Duchene, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-02-15

At the moment ionisation chambers are the detectors which are best suited to the task of nuclear reactor control by neutronic measurements. We have thought it wise to state some generalities concerning reactor dynamics, the various neutron detection methods, the working of ionisation chambers and the measurement methods used. Our contribution to reactor control techniques consists on the one hand in an attempt to make a synthesis of the factors influencing the operation of ionisation chambers, the study of these factors, and on the other hand in the development of ionisation chambers of the fission and boron types, making it possible to follow the working of a reactor from the moment it starts up until maximum power is attained. In the field of fission chambers, we have in particular improved the technique for depositing uranium oxide on aluminium and have perfected the electrolytic deposition process on other metals: stainless steel, copper, molybdenum, nickel, tantalum, titanium, kovar, tungsten and beryllium. We have developed several types of fission chambers used during the start-up of reactors: one type of medium performance now in use in French piles one high-sensitivity type one high-temperature type which has operated up to 600 deg. C. As far as boron chambers are concerned, we have studied the perturbations caused to the measurement by the exposure of the chamber to high neutron flux and to a very strong {gamma} radiation. This exposure brings about a modification of the properties of the constituent materials and causes a background noise in the chamber which can seriously handicap the neutron measurements. We have shown that the compensation technique makes it possible to limit this noise and to thereby increase the range of measurement of conventional ionisation chambers intended for power measurements. Finally, we have built two types of compensation chambers used in the French reactors and have begun the study of a third type of high sensitivity for

Eddy covariance flux measurements of ammonia by high temperature chemical ionisation mass spectrometry

Directory of Open Access Journals (Sweden)

J. Sintermann

2011-03-01

Full Text Available A system for fast ammonia (NH₃ measurements with chemical ionisation mass spectrometry (CIMS based on a commercial Proton Transfer Reaction-Mass Spectrometer (PTR-MS is presented. It uses electron transfer reaction as ionisation pathway and features a drift tube of polyetheretherketone (PEEK and silica-coated steel. Heating the instrumental inlet and the drift tube to 180 °C enabled an effective time resolution of ~1 s and made it possible to apply the instrument for eddy covariance (EC measurements. EC fluxes of NH₃ were measured over two agricultural fields in Oensingen, Switzerland, following fertilisations with cattle slurry. Air was aspirated close to a sonic anemometer at a flow of 100 STP L min⁻¹ and was directed through a 23 m long 1/2" PFA tube heated to 150 °C to an air-conditioned trailer where the gas was sub-sampled from the large bypass stream. This setup minimised damping of fast NH₃ concentration changes between the sampling point and the actual measurement. High-frequency attenuation loss of the NH₃ fluxes of 20 to 40% was quantified and corrected for using an empirical ogive method. The instrumental NH₃ background signal showed a minor interference with H₂O which was characterised in the laboratory. The resulting correction of the NH₃ flux after slurry spreading was less than 1‰. The flux detection limit of the EC system was about 5 ng m⁻² s⁻¹ while the accuracy of individual flux measurements was estimated 16% for the high-flux regime during these experiments. The NH₃ emissions after broad spreading of the slurry showed an initial maximum of 150 μg m⁻² s⁻¹ with a fast decline in the following hours.

Electron spectroscopy of He and NO using electron impact and multiphoton ionisation

International Nuclear Information System (INIS)

Kimman, J.T.N.

1984-01-01

This thesis describes two experimental studies which are intended to contribute to our knowledge of the structure of molecules and the decay dynamics of excited molecular states. The two studies have in common that they are both concerned with ionisation processes, in which an accurately known amount of energy is transferred to the target, and energy analysis of the ejected electrons is made. Ionisation is caused either by scattering electrons off the molecules (chapter 2: electron impact ionisation) or by a simultaneous absorption of several photons (chapter 3: multiphoton ionisation). In chapter 2 an electron impact ionisation experiment on Helium is described in which the kinematics of both the scattered and the ejected electrons is fully determined ((e,2e) experiment). (Auth.)

On the derivation of the ionisation threshold law

International Nuclear Information System (INIS)

Peterkop, R.

1983-01-01

The different procedures for derivation of the electron-atom ionisation threshold law have been analysed and the reasons for discrepancies in the results are pointed out. It is shown that if the wavefunction has a linear node at equal electron distances (r 1 =r 2 ), then the threshold law for the total cross section has the form σ approx. Esup(3m), where σ approx. Esup(m) is the Wannier law. The distribution of energy between escaping electrons is non-uniform and has a parabolic node at equal energies (epsilon 1 = epsilon 2 ). The linear node at opposite directions of electrons (theta = π) does not change the Wannier law but leads to a parabolic node in angular distribution at theta = π. The existence of both nodes leads to the threshold law σ approx. Esup(3m) and to parabolic nodes in energy and angular distributions. (author)

The use of detectors based on ionisation recombination in radiation protection

International Nuclear Information System (INIS)

Sullivan, A.H.

1984-01-01

Intitial recombination of ionisation in a gas depends on the ionisation density and hence on the linear energy transfer along the tracks of charged particles. This effect can be used as a basis for instruments that respond to different types of ionising radiation approximately in the way required by the quality factor-linear energy transfer relation recommended by the ICRP for use in radiation protection. Empirical instruments based on ionisation recombination that have been used for radiation protection measurements are reviewed, and relations are derived from recombination theory that show that the response of such detectors can be readily predicted. The usefulness of recombination instruments in radiation protection is discussed and their advantages and limitations assessed. It is shown that their main application will be as reference instruments against which other detectors can be calibrated. As an extension to using recombination detectors as reference instruments, the feasibility of specifying radiation quality in terms of ionisation recombination is investigated. (author)

Some possible atomic physics experiments with 15 UD pelletron machine

International Nuclear Information System (INIS)

Mandal, A.

1995-01-01

Some possible experiments in atomic physics using medium energy heavy ion beam from the Pelletron are discussed. Main discussions is on x-ray spectroscopy using heavy ion beam. Different excitation mechanisms of inner atomic shells, experimental results and comparison with different theoretical models are presented. Effects of multiple vacancies in outer shells on K-shell ionisation, projectile charge state and target thickness effects are discussed. High resolution x-ray spectroscopy using curved crystal spectrometer is useful for studying these effects. Special emphasis is given to the study of quasi-molecular orbit (MO) formation during adiabatic collision of heavy ion with atom. Different aspects of MO x-ray study are presented. Other continuum x-rays e.g. radiative electron capture (REC), secondary electron Bremsstrahlung (SEB) nucleus-nucleus Bremsstrahlung (NNB) etc are also discussed. (author). 16 refs., 5 figs

Medical exposure to ionising radiation and the risk of brain tumours

DEFF Research Database (Denmark)

Blettner, Maria; Schlehofer, Brigitte; Samkange-Zeeb, Florence

2007-01-01

BACKGROUND: The role of exposure to low doses of ionising radiation in the aetiology of brain tumours has yet to be clarified. The objective of this study was to investigate the association between medically or occupationally related exposure to ionising radiation and brain tumours. METHODS: We...... used self-reported medical and occupational data collected during the German part of a multinational case-control study on mobile phone use and the risk of brain tumours (Interphone study) for the analyses. RESULTS: For any exposure to medical ionising radiation we found odds ratios (ORs) of 0.63 (95...... regions. CONCLUSION: We did not find any significant increased risk of brain tumours for exposure to medical ionising radiation....

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

Nanoscale photoelectron ionisation detector based on lanthanum hexaboride

International Nuclear Information System (INIS)

Zimmer, C.M.; Kunze, U.; Schubert, J.; Hamann, S.; Doll, T.

2011-01-01

A nanoscale ioniser is presented exceeding the limitation of conventional photoionisation detectors. It employs accelerated photoelectrons that allow obtaining molecule specificity by the tuning of ionisation energies. The material lanthanum hexaboride (LaB 6 ) is used as air stable photo cathode. Thin films of that material deposited by pulsed laser deposition (PLD) show quantum efficiency (QE) in the range of 10 -5 which is comparable to laser photo stimulation results. A careful treatment of the material yields reasonable low work functions even after surface reoxidation which opens up the possibility of using ultraviolet light emitting diodes (UV LEDs) in replacement of discharge lamps. Schematic diagram of a photoelectron ionisation detector (PeID) operating by an electron emitter based on the photoelectric effect of lanthanum hexaboride. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Measurement of the activity of beta emitting gases using an ionisation chamber; Mesure de l'activite des gaz emetteurs beta au moyen d'une chambre d'ionisation

Energy Technology Data Exchange (ETDEWEB)

Lebouleux, P [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

1962-07-01

An ionization chamber was developed for measuring directly the activity of a {beta}-emitting gas whatever the gas may be. The following two parameters are defined and determined: p, the average specific ionization produced by a {beta} disintegration, and i, the average {beta} path in the chamber. It was shown, during the determination of i, that the {beta} particles are reflected on the walls of the ionization chamber when the latter are made of a high atomic number material. It was possible to eliminate this effect by constructing an electrode chamber made of graphite. With this chamber a direct measurement can be made of the activity of a gaseous {beta} emitter with a precision of about {+-}10%. Some applications are given of the graphite electrode chamber (calibration of the chambers built industrially and determination of the activation cross section of a gaseous emitter). It was possible to determine the activation cross section of {sup 134}Xe; a value of 0.18 {+-} 0.03 barn was found. (author) [French] Le but de l'etude est de realiser une chambre d'ionisation permettant d'effectuer une mesure directe de l'activite d'un gaz emetteur {beta} quel que soit l'emetteur considere. On definit et l'on determine les deux parametres suivants: p: ionisation specifique moyenne produite par une desintegration {beta}. La determination est effectuee par une methode graphique, i: moyenne des parcours des {beta} dans la chambre. La determination est effectuee experimentalement par introduction dans la chambre d'un gaz radioactif dont on peut calculer l'activite. On a mis en evidence, au cours de la determination de i, la reflexion des particules {beta} sur les parois des chambres d'ionisation lorsque celles-ci sont constituees d'un materiau de numero atomique eleve. La construction d'une chambre a electrodes de graphite nous a permis d'eliminer ce phenomene. Avec cette chambre, on effectue une mesure directe de l'activite d'un emetteur {beta} gazeux avec une precision de l

Characterisation of chemical components for identifying historical Chinese textile dyes by ultra high performance liquid chromatography – photodiode array – electrospray ionisation mass spectrometer

NARCIS (Netherlands)

Han, J.; Wanrooij, J.; van Bommel, M.; Quye, A.

2017-01-01

This research makes the first attempt to apply Ultra High Performance Liquid Chromatography (UHPLC) coupled to both Photodiode Array detection (PDA) and Electrospray Ionisation Mass Spectrometer (ESI–MS) to the chemical characterisation of common textile dyes in ancient China. Three different

Atomic collisions research with excited atomic species

International Nuclear Information System (INIS)

Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

Argon line broadening by neutral atoms and application to the measurement of oscillator strengths of AI resonance lines

International Nuclear Information System (INIS)

Vallee, O.; Ranson, P.; Chapelle, J.

1977-01-01

AI line broadening was studied from collisions between neutral argon atoms (3p 5 4p-3p 5 4s transitions) in a weakly ionised plasma jet (neutral atoms temperature T 0 approximately 4000K, electrons temperature Tsub(e) approximately 6000K, electronic density Nsub(e) 15 cm -3 , ionisation rate α -4 , and pressure range from 1 to 3 kg/cm 2 ). A satisfactory description of Van der Waals broadened lines is obtained by means of a Lennard-Jones potential. Measurement of line widths whose corresponding transitions occur on resonant levels, gives with relatively good accuracy the oscillator strength of the argon resonance lines [fr

High-magnetic field atomic physics

International Nuclear Information System (INIS)

Gay, J.C.

1984-01-01

This chapter discusses both the traditional developments of Zeeman techniques at strong fields and the fundamental concepts of diamagnetism. Topics considered include historical aspects, the production of high fields, the atom in a magnetic field (Hamiltonian and symmetries, the various magnetic regimes in atomic spectra), applications of the Zeeman effect at strong B fields, the Landau regime for loosely bound particles, theoretical concepts of atomic diamagnetism, and the ultra-high-field regime and quantum electrodynamics. It is concluded that the wide implications of the problem of the strongly magnetized hydrogen atom in various domains of physics and its conceptual importance concerning theoretical methods of classical and quantum mechanics justify the experimental and theoretical efforts in atomic physics

Disposal regulations and techniques applicable to devices using ionising radiation

International Nuclear Information System (INIS)

Vidal, J.P.

1998-01-01

L'office de Protection contre les rayonnement ionisants, being a government body under the supervision of Ministry of Health and Labour, among other different missions controls the compliance of radiation protection laws with the aim to guarantee the safe operation of equipment using ionising radiation sources. These regulations concerning competence of personnel, especially in the field of medicine or application of ionising radiation on humans, are restricted only to medical doctors (or dentists in their domain) by technical constraints dealing with design of equipment and its exploitation. At the same time regulations define conditions of permanent control in order to verify compliance of radiation protection laws

Atomic energy act, 2008: Acts supplement no. 12 to the Uganda gazette no. 61 volume CI dated 5th December, 2008

International Nuclear Information System (INIS)

2008-01-01

The Act regulates peaceful application of ionising radiation, establishes the Atomic Energy Council, it provides for the protection and safety of individuals, society and the environment from dangers resulting from ionising radiation; for the production use of radiation sources and the management of radioactive wastes. It also provides for a framework for the promotion and development of nuclear energy for use in power generation and other peaceful purposes. It sets requirements for compliance with international safety and for the use of ionising radiation, radiation protection, and security of radioactive sources.

Distorted-wave calculations of electron impact ionisation in the Ni isonuclear sequence

Energy Technology Data Exchange (ETDEWEB)

Griffin, D C; Pindzola, M S

1988-10-14

Electron impact ionisation cross sections for Ni/sup +/, Ni/sup 3+/, Ni/sup 5+/, Ni/sup 6+/, Ni/sup 7+/, Ni/sup 8+/, Ni/sup 12+/, Ni/sup 14+/, and Ni/sup 16+/ are calculated in the distorted-wave approximation. These calculations include contributions from direct ionisation and inner-shell excitation followed by autoionisation. For Ni/sup 12+/, Ni/sup 14+/, and Ni/sup 16+/ we report not only on ionisation cross sections from the ground states but also from the metastable states of these ions. Experimental cross section measurements exist for all ions reported here, except Ni/sup 16+/. The agreement between experiment and theory is reasonably good and improves with ionisation stage.

Determination of the ionisation potential of certain hydrocarbons in the liquid phase

International Nuclear Information System (INIS)

Casanovas, J.; Grob, R.; Brunet, G.; Sabattier, R.; Guelfucci, J.P.; Blanc, D.

1978-01-01

The first results obtained are presented on the determination of the ionisation potential of four alkanes (n-hexane, n-pentane, cyclopentane and trimethyl-2,2,4 pentane) in the liquid phase. In the gaseous phase, the ionisation potential values of these hydrocarbons are respectively 10.18 eV for n-hexane, 10.35 eV for n-pentane, 10.53 eV for cyclopentane and 9.86 eV for trimethyl-2,2,4 pentane. Consequently rare gas resonance lamps (krypton and Xenon) were made, sealed and excited by an ultra-high frequency wave, which emit photons in the energy field concerned, i.e. from 8.5 eV to 11eV. The energy of the photons emitted by these lamps is respectively 8.44 eV (100%) and 9.57 eV (2%) for xenon and 10.03 eV (100%) and 10.64 eV (5%) for krypton. From the extent of the induced ionisation currents and particularly the value of the ratio of the currents induced by the photons of the krypton and xenon lamps, a minimum value of the ionisation potential drop can be deduced compared with the gas phase of 0.61 eV for n-hexane, 0.78 eV for n-pentane, 0.96 eV for cyclopentane and a maximum value of 1.42 eV for trimethyl-2,2,4 pentane [fr

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

Ionisation Chambers for the LHC Beam Loss Detection

CERN Document Server

Gschwendtner, E; Dehning, B; Ferioli, G; Kain, V

2003-01-01

At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Since the stored particle beam intensity is 8 orders of magnitude larger than the lowest quench level value particular attention is paid to the design of the secondary particle shower detectors. The foreseen ionisation chambers are optimised in geometry simulating the probable loss distribution along the magnets and convoluting the loss distribution with the secondary particle shower distributions. To reach the appropriate coverage of a particle loss and to determine the quench levels with a relative accuracy of 2 the number of the detectors and their lengths is weighted against the particle intensity density variation. In addition attention is paid to the electrical ionisation chamber signal to minimise the ion tail extension. This optimisation is based on time resolved test measurements in the PS booster. A proposal for a new ionisation chamber will be pre...

Electron removal from H and He atoms in collisions with C q+ , O q+ ions

Science.gov (United States)

Janev, R. K.; McDowell, M. R. C.

1984-06-01

Cross sections for electron capture and ionisation in collision of partially and completely stripped C q+ , N q+ and O q+ ions with hydrogen and helium atoms have been calculated at selected energies. The classical trajectory Monte Carlo method was used with a variable-charge pseudopotential to describe the interaction of the active electron with the projectile ion. A scalling relationship has been derived for the electron removal (capture and ionisation) cross section which allows a unifield representation of the data.

The biological effects of exposure to ionising radiation

International Nuclear Information System (INIS)

Higson, D.J.

2016-01-01

Scenarios for exposure to ionising radiation range from natural background radiation (chronic) to the explosions of atomic bombs (acute), with some medical, industrial and research exposures lying between these extremes. Biological responses to radiation that predominate at high doses incurred at high dose rates are different from those that predominate at low doses and low dose rates. Single doses from bomb explosions ranged up to many thousand mGy. Acute doses greater than about 1000 mGy cause acute radiation syndrome (ARS). Below this threshold, radiation has a variety of potential latent health effects: Change to the incidence of cancer is the most usual subject of attention but change to longevity may be the best overall measure because decreased incidences of non-cancer mortality have been observed to coincide with increased incidence of cancer mortality. Acute doses greater than 500 mGy cause increased risks of cancer and decreased life expectancy. For doses less than 100 mGy, beneficial overall health effects ('radiation hormesis') have been observed. At the other end of the spectrum, chronic exposure to natural radiation has occurred throughout evolution and is necessary for the normal life and health of current species. Dose rates greater than the present global average of about 2 mGy per year have either no discernible health effect or beneficial health effects up to several hundred mGy per year. It is clearly not credible that a single health effects model -- such as the linear no-threshold (LNT) model of risk estimation -- could fit all latent health effects. A more realistic model is suggested.

The case against protecting the environment from ionising radiation

International Nuclear Information System (INIS)

Smith, J.T.

2004-01-01

The objective of this paper is to present the (rarely heard) argument in favour of retention of the present system of radiation protection of the environment. There has been a recent trend in the radioecological and radiation protection community towards greater regulation of the effects of ionising radiations on biota. In particular, the often quoted International Commission on Radiation Protection (ICRP) hypothesis that: If humans are protected from the effects of ionising radiation, then flora and fauna are also adequately protected has been criticised as being too anthropocentric and not adequate for protection of the environment. In this paper I will challenge this view, arguing firstly that this statement is almost always quoted out of its proper context, and secondly that the ICRP hypothesis does adequately protect the environment from the effects of ionising radiations. In view of the relatively insignificant effect of regulated releases of ionising radiation on the environment, the economic cost of further regulation will not result in a significant environmental benefit. Whilst empirical research to test the ICRP hypothesis should continue, until there is clear evidence against it, this simple and cost-effective approach should be retained. This would benefit the environment by directing scarce resources to more urgent environmental problems. (author)

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

Quantification of complex DNA damage by ionising radiation. An experimental and theoretical approach

International Nuclear Information System (INIS)

Fulford, J.

2000-05-01

Ionising radiation potentially produces a broad spectrum of damage in DNA including single and double strand breaks (ssb and dsb) and base damages. It has been hypothesised that sites of complex damage within cellular DNA have particular biological significance due to an associated decreased efficiency in repair. The aim of this study is to gain further understanding of the formation of complex DNA damage. Irradiations of plasmid DNA illustrate that an increase in ionising density of the radiation results in a decrease in ssb yields/Gy but an increase in dsb per ssb, indicative of an increase in the number of complex damage sites per simple isolated damage site. As the mechanism for damage formation shifts from purely indirect at low scavenging capacities to a significant proportion of direct at higher scavenging capacities the proportion of complex damage increases. Comparisons with the yields of ssb and dsb simulated by Monte-Carlo calculations for Al K USX and α-particles also indicate this correspondence. The ionisation density of low energy, secondary electrons produced by photons was assessed experimentally from the dependence of the yield of OH radicals escaping intra-track recombination on photon energy. As energy decreases the OH radical yield initially decreases reflecting an increased ionisation density. However, with further decrease in photon energy the yield of OH radicals increases in line with theoretical calculations. Base damage yields were determined for low and high ionising density radiation over a range of scavenging capacities. As scavenging capacity increases the base damage: ssb ratios increases implying a contribution from electrons to base damage. It is proposed that base damage contributes to DNA damage complexity. Complex damage analysis reveals that at cell mimetic scavenging capacities, 23% and 72% of ssb have an additional spatially close damage site following γ-ray and α-particle irradiation respectively. (author)

Critical ionisation velocity and the dynamics of a coaxial plasma gun

International Nuclear Information System (INIS)

Raadu, M.A.

1978-01-01

The dynamics of an ionising wave in a coaxial plasma gun with an azimuthal bias magnetic field is analysed in a theoretical model. Only the radial dependence is treated and instead of including a treatment of the energy balance two separate physical assumptions are made. In the first case it is assumed that the total internal electric field is given by the critical ionisation velocity condition and in the second that the ionisation rate is constant. For consistency wall sheaths are assumed to match the internal plasma potential to that of the walls. On the basis of momentum and particle balance the radial dependence of the electron density, current density, electric field and drift velocity are found. An electron source is required at the cathode and the relative contribution from ionisation within the plasma is deduced. The assumption that there are no ion sources at the electrodes leads to a restriction on the possible values of the axial electric field. (author)

Ionisation detectors as monitors of toxic compounds in air

International Nuclear Information System (INIS)

Leonhardt, J.W.

1994-01-01

Beta particles cause ionisation in gas mixtures. The ions produced provide information on the concentration and identity of trace compounds in ambient air. Modern ionisation detectors use ion mobilities to monitor toxic compounds. Chemical solvent, phosphororganic compounds, PCB and many other toxins can be detected using ion mobility detectors (IMD) in the ppb range or lower. Ion mobility detectors have large potential in industry and research because of their sensitivity, specificity, fast response and relatively low cost. Portable devices and fixed installations are possible. The paper discusses the following topics: (1) ionisation sources in IMD: 63 Ni, 3 H, photoionization and corona discharge, (2) basic principles of ion production, (3) ion collection in IMD, (4) design, gas supply, automatic identification and quantification of IMD data, and (5) selected applications. Advantages and problems with this new type of nuclear analytical instrument are also discussed. (author). 2 refs., 9 figs., 3 tabs

Systematics of atom-atom collision strengths at high speeds

International Nuclear Information System (INIS)

Gillespie, G.H.; Inokuti, M.

1980-01-01

The collision strengths for atom-atom collisions at high speeds are calculated in the first Born approximation. We studied four classes of collisions, distinguished depending upon whether each of the collision partners becomes excited or not. The results of numerical calculations of the collision strengths are presented for all neutral atoms with Z< or =18. The calculations are based on atomic form factors and incoherent scattering functions found in the literature. The relative contribution of each class of collision processes to the total collision cross section is examined in detail. In general, inelastic processes dominate for low-Z atoms, while elastic scattering is more important for large Z. Other systematics of the collision strengths are comprehensively discussed. The relevant experimental literature has been surveyed and the results of this work for the three collision systems H-He, He-He, and H-Ar are compared with the data for electron-loss processes. Finally, suggestions are made for future work in measurements of atom-atom and ion-atom collision cross sections

Antioxidant Protection in Blood against Ionising Radiation

International Nuclear Information System (INIS)

Bognar, G.; Meszaros, G.; Koteles, G. J.

2001-01-01

Full text: The quantities of the antioxidants in the human blood are important indicators of health status. The routine determinations of activities/capacities of antioxidant compounds would be of great importance in assessing individual sensitivities against oxidative effects. We have investigated the sensitivities of those antioxidant elements against various doses of ionising radiation tested by the RANDOX assays. Our results show dose-dependent decreases of antioxidant activities caused by the different doses. The total antioxidant status value linearly decreased up to 1 Gy, but further increase of dose (2 Gy) did not influence the respective values although the test system still indicated their presence. It means that the human blood retains 60-70% of its total antioxidant capacity. Radiation induced alterations of the antioxidant enzymes: glutathione peroxidase and superoxide dismutase have been also investigated. The activities of glutathione peroxidase and superoxide dismutase decreased linearly upon the effects of various doses of ionising radiation till 1 Gy. Between 1 and 2 Gy only further mild decreases could be detected. In this case the human blood retained 40-60% of these two antioxidant enzymes. These observations suggest either the limited response of antioxidant system against ionising radiation, or the existence of protection system of various reactabilities. (author)

Working safely with ionising radiation

International Nuclear Information System (INIS)

McDowell, D.J.

1990-01-01

A small leaflet provides information on working safely with ionizing radiation. Topics covered include the types of radiation, radiological units, external radiation, contamination and internal radiation, methods of protection form radiation, radiation monitors, protective clothing for contamination, personal dosemeters, radiation dose limits for classified workers and finally the Ionising Radiations Regulations 1985. (UK)

Updated estimates of the proportion of childhood leukaemia incidence in Great Britain that may be caused by natural background ionising radiation

International Nuclear Information System (INIS)

Little, Mark P; Wakeford, Richard; Kendall, Gerald M

2009-01-01

The aetiology of childhood leukaemia remains generally unknown, although exposure to moderate and high levels of ionising radiation, such as was experienced during the atomic bombings of Japan or from radiotherapy, is an established cause. Risk models based primarily upon studies of the Japanese A-bomb survivors imply that low-level exposure to ionising radiation, including to ubiquitous natural background radiation, also raises the risk of childhood leukaemia. In a recent paper (Wakeford et al 2009 Leukaemia 23 770-6) we estimated the proportion of childhood leukaemia incidence in Great Britain attributable to natural background radiation to be about 20%. In this paper we employ the two sets of published leukaemia risk models used previously, but use recently published revised estimates of natural background radiation doses received by the red bone marrow of British children to update the previous results. Using the newer dosimetry we calculate that the best estimate of the proportion of cases of childhood leukaemia in Great Britain predicted to be attributable to this source of exposure is 15-20%, although the uncertainty associated with certain stages in the calculation (e.g. the nature of the transfer of risk between populations and the pertinent dose received from naturally occurring alpha-particle-emitting radionuclides) is significant. The slightly lower attributable proportions compared with those previously derived by Wakeford et al (Leukaemia 2009 23 770-6) are largely due to the lower doses (and in particular lower high LET doses) for the first year of life.

Beam Cooling with ionisation losses

CERN Document Server

Rubbia, Carlo; Kadi, Y; Vlachoudis, V

2006-01-01

A novel type of particle "cooling", called Ionization Cooling, is applicable to slow (v of the order of 0.1c) ions stored in a small ring. The many traversals through a thin foil enhance the nuclear reaction probability, in a steady configuration in which ionisation losses are recovered at each turn by a RF-cavity. For a uniform target "foil" the longitudinal momentum spread diverges exponentially since faster (slower) particles ionise less (more) than the average. In order to "cool" also longitudinally, a chromaticity has to be introduced with a wedge shaped "foil". Multiple scattering and straggling are then "cooled" in all three dimensions, with a method similar to the one of synchrotron cooling, but valid for low energy ions. Particles then stably circulate in the beam indefinitely, until they undergo for instance nuclear processes in the thin target foil. This new method is under consideration for the nuclear production of a few MeV/A ion beams. Simple reactions, for instance Li 7 + D Li 8 + p, are more ...

Experiments on state selection and Penning ionisation with fast metastable rare gas atoms

International Nuclear Information System (INIS)

Kroon, J.P.C.

1985-01-01

This thesis describes experiments with metastable He/Ne atoms. The experiments are performed in a crossed beam machine. Two different sources are used for the production of metastable atoms: a source for the production of metastable atoms in the thermal energy range and a hollow cathode arc for the production of metastable atoms in the superthermal energy range (1-7 eV). The progress made in the use of the hollow cathode arc is described as well as the experimental set-up. The rare gas energy-level diagram is characterized by two metastable levels. By optical pumping it is possible to select a single metastable level, both for He and Ne. For the case of He this is done by a recently built He quenchlamp which selectively quenches the metastable 2 1 S level population. In the thermal energy range the quenching is complete; in the superthermal energy range the 2 1 S level population is only partly quenched. For the optical pumping of Ne* atoms a cw dye laser is used. New experiments have been started on the measurement, in a crossed beam machine, of the fluorescence caused by inelastic collisions where metastable atoms are involved. The He* + Ne system is used as a pilot study for these experiments. The He-Ne laser is based on this collision system. (Auth.)

Calibration of ARI QC ionisation chambers using the Australian secondary standards for activity

International Nuclear Information System (INIS)

Mo, L.; Van Der Gaast, H.A.; Alexiev, D.; Butcher, K.S.A.; Davies, J.

1999-01-01

The Secondary Standard Activity Laboratory (SSAL) in ANSTO routinely provides standardised radioactive sources, traceable activity measurements and custom source preparation services to customers. The most important activity carried out is the calibration of ionisation chambers located in the Quality Control (QC) section of Australian Radioisotopes (ARI). This ensures that their activity measurements are traceable to the Australian primary methods of standardisation. ARI QC ionisation chambers are calibrated for 99m Tc, 67 Ga, 131 I, 201 Tl and 153 Sm. The SSAL has a TPA ionisation chamber, which has been directly calibrated against a primary standard for a variety of radioactive nuclides. Calibration factors for this chamber were determined specifically for the actual volumes (5ml for 99m Tc, 131 I, 2ml for 67 Ga, 201 Tl and 3 ml for 153 Sm) and types of vial (Wheaton) which are routinely used at ARI. These calibration factors can be used to accurately measure the activity of samples prepared by ARI. The samples can subsequently be used to calibrate the QC ionisation chambers. QC ionisation chambers are re-calibrated biannually

High-dimensional atom localization via spontaneously generated coherence in a microwave-driven atomic system.

Science.gov (United States)

Wang, Zhiping; Chen, Jinyu; Yu, Benli

2017-02-20

We investigate the two-dimensional (2D) and three-dimensional (3D) atom localization behaviors via spontaneously generated coherence in a microwave-driven four-level atomic system. Owing to the space-dependent atom-field interaction, it is found that the detecting probability and precision of 2D and 3D atom localization behaviors can be significantly improved via adjusting the system parameters, the phase, amplitude, and initial population distribution. Interestingly, the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength. Our scheme opens a promising way to achieve high-precision and high-efficiency atom localization, which provides some potential applications in high-dimensional atom nanolithography.

Ionising radiation. Part 2

International Nuclear Information System (INIS)

2000-01-01

A brief tutorial on the health effects of ionising radiation is presented. The distinction between somatic and genetic health effects is explained. The two types of somatic health effects, i.e., acute and chronic effects, are discussed, as well as the concepts of ''deterministic'' and ''stochastic'' (also called ''probabilistic'') health effects. The possibility of cancer caused by DNA damage is discussed. The document ends with the definition of some key radiation terms

IRID: specifications for the Ionising Radiations Incident Database

International Nuclear Information System (INIS)

Thomas, G.O.; Croft, J.R.; Williams, M.K.; McHugh, J.O.

1996-01-01

Technologies that make use of ionising radiations are widespread. They provide many benefits but, as with other technologies, the use of ionising radiations carries with it the potential for incidents and accidents. Their severity can vary from the trivial to the fatal and may involve substantial economic penalties. In order to minimise the number of incidents and their consequences it is important that there is a mechanism to learn the lessons from those that do occur. To help pursue this objective the National Radiological Protection Board, the Health and Safety Executive and the Environment Agency have established a national Ionising Radiations Incident Database (IRID) to cover radiation incidents in industry, medicine, research and teaching. This publication details the specifications for IRID and its methods of operation. All information in the database will be unattributable and names of persons or organisations will not be included. It is a personal computer based system with 24 fields to categorise an incident, including a text field that will provide a description of the incident giving the causes, consequences, follow-up actions and lessons to be learned. These descriptions will be used in subsequent publications to provide feedback to the users. (UK)

Dose limits for ionising radiation

International Nuclear Information System (INIS)

Gifford, D.

1989-01-01

Dose limits for exposure to ionising radiation are assessed to see if they give sufficient protection both for the occupationally exposed and for the general public. It is concluded that current limits give a level of safety that satisfies the necessary criteria in the light of present knowledge and further reductions would be unlikely to improve standards of safety. (author)

Use of ionising radiation for food processing applications

International Nuclear Information System (INIS)

Ninjoor, V.

1989-01-01

Food irradiation is a recently developed technique used to sterilize and preserve food. Food products are exposed to ionising radiations such as X-rays, gamma rays or high energy electrons which destroy food borne pathogens and parasites and inhibit sprouting. Shelf life of food is extended. The following aspects of radiation processing of food are discussed in the monograph: radiation sources, choice of dose for specific results, safety and nutritional quality of radiation processed food, international status of acceptance of food irradiation, and cost. (M.G.B.). 6 tabs

Biological monitors for low levels of ionising radiation

International Nuclear Information System (INIS)

Mohankumar, M.N.; Jeevanram, R.K.

1995-01-01

The biological effects of high doses of ionising radiation are well understood and the methods of measurement of these doses well established. However the effects due to extremely low doses remain by and large uncertain. This is because of the fact that at such low doses no gross symptoms are seen. In fact, at these levels the occurrence of double strand breaks leading to the formation of chromosomal aberrations like dicentrics is rare and chances of mutation due to base damage are negligible. Hence neither chromosomal aberration studies nor mutational assays are useful for detecting doses of the order of a few milligray. Results of exhaustive work done by various laboratories indicate that below 20 mGy the chromosomal aberration technique based on scoring of dicentrics cannot distinguish between a linear or a threshold model. However indirect methods like unscheduled DNA synthesis (UDS) and sister chromatid exchanges (SCEs) appear to be promising for the detection of radiation exposures due to low levels of radiation. This report reviews the available literature on the biological effects of low levels of ionising radiation and highlights the merits and demerits of the various methods employed in the measurement of UDS and SCE. The phenomenon of radio-adaptive response (RAR) and its relation to DNA repair is also discussed. (author)

High-speed cinematography of gas-metal atomization

Energy Technology Data Exchange (ETDEWEB)

Ting, Jason [ALCOA Specialty Metals Division, 100 Technical Drive, Alcoa Center, PA 15069 (United States)]. E-mail: jason.ting@alcoa.com; Connor, Jeffery [Material Science Engineering Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Ridder, Stephen [Metallurgical Processing Group, NIST, 100 Bureau Dr. Stop 8556, Gaithersburg, MD 20899 (United States)

2005-01-15

A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.

High-speed cinematography of gas-metal atomization

International Nuclear Information System (INIS)

Ting, Jason; Connor, Jeffery; Ridder, Stephen

2005-01-01

A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images

Characterisation of bacteria by matrix-assisted laser desorption/ionisation and electrospray mass spectrometry

NARCIS (Netherlands)

Baar, B.L.M. van

2000-01-01

Chemical analysis for the characterisation of micro-organisms is rapidly evolving, after the recent advent of new ionisation methods in mass spectrometry (MS): electrospray (ES) and matrix-assisted laser desorption/ionisation (MALDI). These methods allow quick characterisation of micro-organisms,

Ionisation and dissociation of water induced by swift multicharged ions

International Nuclear Information System (INIS)

Legendre, S.

2006-02-01

Ionization and dissociation of water molecules and water clusters induced by 11.7 MeV/A Ni 25+ ions were carried out by imaging techniques. Branching ratios, ionisation cross sections and Kinetic Energy Released distributions have been measured together with fragmentation dynamics studies. Multiple ionization represents approximately 30% of the ionizing events. Double ionization produces in significant way atomic oxygen, considered as a possible precursor of the large production of HO 2 radical in liquid water radiolysis by ions of high Linear Energy Transfer. We evidence a strong selectivity of bond breakage in the case of ion-induced HOD fragmentation. Once the molecule doubly ionized, the breakage of the O-H bond is found 6.5 times more probable than that of the O-D bond. A semi-classical calculation simulating the fragmentation dynamics on the potential energy surface of the ground-state of di-cation H 2 O 2+ makes possible to as well reproduce the preferential nature of the breakage of the O-H bond as the position and the shift of the kinetic energy distributions. First results concerning interaction with water clusters are also reported. Measurements in coincidence are carried out giving access to correlation, with the distributions in energy and angle of the emitted fragments. Mass spectrum points fast intra-cluster proton transfer, leading to the emission of protonated clusters. (author)

Advisory group on ionising radiation

International Nuclear Information System (INIS)

Harrison, J.R.

1996-01-01

The Advisory Group on Ionising Radiation has a busy and challenging work programme. Its reports will be published in the Documents of the NRPB series. These may advise further research or could form the basis of formal NRPB advice. Covering the full spectrum of radiation issues at work, in public health and clinical medicine, and the environment, it should enhance the radiation advice available to NRPB. (author)

Measurement of the electronic density of ionised media by hyper frequency methods; Mesure de la densite electronique des milieux ionises par des methodes hyperfrequences

Energy Technology Data Exchange (ETDEWEB)

Consoli, T [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

Within the limits of the I.N.S.T.N. courses on plasmas, this analytical study summarizes the articles quoted in the references on hyper-frequency techniques for the measurement of electronic density of an ionised gas. It is neither exhaustive nor complete and further details may be obtained by referring to the works mentioned. The first part, devoted to the theoretical side, concert the propagation of electromagnetic waves ionised media and the excitation of stationary raves in electromagnetic cavities. The second part deals with the measurement techniques themselves. It includes those techniques which hare become classic, and also more recent ones being developed in various laboratories and in the Service of Applied Physics at Saclay. (author) [French] Dans le cadre des cours sur les plasmas a l'l.N.S.T. cette etude d'analyse resume les articles cites en bibliographie sur les techniques hyperfrequences pour la mesure de la densite electronique d'un gas ionise. Elle n'est ni exhaustive, ni complete. Pour plus de details on voudra bien se rapporter aux travaux mentionnes. La premiere partie consacree a des rappels theoriques, concerne la propagation des ondes electromagnetiques dans les milieux ionises et sur l'excitation d'ondes stationnaires dans les cavites electromagnetiques. La seconde se rapporte aux techniques de mesures proprement dites. On a fait figurer dans cette partie des techniques devenues classiques et celles plus recentes en cours d'etudes dans divers laboratoires et au Service de Physique Appliquee a SACLAY. (auteur)

Atomic structure of highly-charged ions. Final report

International Nuclear Information System (INIS)

Livingston, A. Eugene

2002-01-01

Atomic properties of multiply charged ions have been investigated using excitation of energetic heavy ion beams. Spectroscopy of excited atomic transitions has been applied from the visible to the extreme ultraviolet wavelength regions to provide accurate atomic structure and transition rate data in selected highly ionized atoms. High-resolution position-sensitive photon detection has been introduced for measurements in the ultraviolet region. The detailed structures of Rydberg states in highly charged beryllium-like ions have been measured as a test of long-range electron-ion interactions. The measurements are supported by multiconfiguration Dirac-Fock calculations and by many-body perturbation theory. The high-angular-momentum Rydberg transitions may be used to establish reference wavelengths and improve the accuracy of ionization energies in highly charged systems. Precision wavelength measurements in highly charged few-electron ions have been performed to test the most accurate relativistic atomic structure calculations for prominent low-lying excited states. Lifetime measurements for allowed and forbidden transitions in highly charged few-electron ions have been made to test theoretical transition matrix elements for simple atomic systems. Precision lifetime measurements in laser-excited alkali atoms have been initiated to establish the accuracy of relativistic atomic many-body theory in many-electron systems

Recent experiments involving highly excited atoms

International Nuclear Information System (INIS)

Latimer, C.J.

1979-01-01

Very large and fragile atoms may be produced by exciting normal atoms with light or by collisions with other atomic particles. Atoms as large as 10 -6 m are now routinely produced in the laboratory and their properties studied. In this review some of the simpler experimental methods available for the production and detection of such atoms are described including tunable dye laser-excitation and field ionization. A few recent experiments which illustrate the collision properties and the effects of electric and and magnetic fields are also described. The relevance of highly excited atoms in other areas of research including radioastronomy and isotope separation are discussed. (author)

High-energy atomic physics

CERN Document Server

Drukarev, Evgeny G

2016-01-01

This self-contained text introduces readers to the field of high-energy atomic physics - a new regime of photon-atom interactions in which the photon energies significantly exceed the atomic or molecular binding energies, and which opened up with the recent advent of new synchrotron sources. From a theoretical point of view, a small-parameter characteristic of the bound system emerged, making it possible to perform analytic perturbative calculations that can in turn serve as benchmarks for more powerful numerical computations. The first part of the book introduces readers to the foundations of this new regime and its theoretical treatment. In particular, the validity of the small-parameter perturbation expansion and of the lowest-order approximation is critically reviewed. The following chapters then apply these insights to various atomic processes, such as photoionization as a many-body problem, dominant mechanisms for the production of ions at higher energies, Compton scattering and ionization accompanied b...

A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry

International Nuclear Information System (INIS)

Murawski, I.; Zielczynski, M.; Gryzinski, M.A.; Golnik, N.

2014-01-01

A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge. Air-filled ionisation chamber with very small gap is a simple dosemeter, which fulfills the most desired properties of criticality accident dosemeters. Short ion collection time is achieved by combination of small gap and relatively high polarising voltage. For the same reason, parasitic recombination of ions in the chamber is negligibly small even at high dose rates. The difference between neutron and gamma sensitivity is small for tissue-equivalent chamber and is expected to become practically negligible when the chamber electrodes are made of polypropylene. Additional capacitor provides a broad measuring range from ∼0.1 Gy up to ∼25 Gy; however, leakage of electrical charge from polarising capacitor has to be observed and taken into account. Periodical re-charging of the device is necessary. Obviously, final test of the device in conditions simulating criticality accident is needed and will be performed as soon as available. (authors)

Extra holiday because of ionising radiation not necessary

International Nuclear Information System (INIS)

Anon.

1978-01-01

The 'regulations for special measures to protect employees working with X-rays and radium radiation' of 21st November 1947, which included a statutory six-week holiday period annually, has now been superceded by 'regulations on special protective measures for work with ionising radiation', issued by the Directorate for Work Inspection on 31st March 1978, effective from 1st May 1978. In addition to removing the requirement for six weeks annual holiday for radiation personnel, routine medical surveillance is only required every third year instead of annually. A number of other changes are mentioned. The basis for these changes is that continuous personnel dosimetry and better knowledge of the effects of ionising radiation allows any necessary measures to be taken on the basis of these. (JIW)

Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z 0.7

Science.gov (United States)

Epinat, B.; Contini, T.; Finley, H.; Boogaard, L. A.; Guérou, A.; Brinchmann, J.; Carton, D.; Michel-Dansac, L.; Bacon, R.; Cantalupo, S.; Carollo, M.; Hamer, S.; Kollatschny, W.; Krajnović, D.; Marino, R. A.; Richard, J.; Soucail, G.; Weilbacher, P. M.; Wisotzki, L.

2018-01-01

We report the discovery of a 104 kpc2 gaseous structure detected in [O II]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of ( 5 ± 3) × 1010 M⊙ and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O III]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures. Based on observations made with

High-precision atom localization via controllable spontaneous emission in a cycle-configuration atomic system.

Science.gov (United States)

Ding, Chunling; Li, Jiahua; Yu, Rong; Hao, Xiangying; Wu, Ying

2012-03-26

A scheme for realizing two-dimensional (2D) atom localization is proposed based on controllable spontaneous emission in a coherently driven cycle-configuration atomic system. As the spatial-position-dependent atom-field interaction, the frequency of the spontaneously emitted photon carries the information about the position of the atom. Therefore, by detecting the emitted photon one could obtain the position information available, and then we demonstrate high-precision and high-resolution 2D atom localization induced by the quantum interference between the multiple spontaneous decay channels. Moreover, we can achieve 100% probability of finding the atom at an expected position by choosing appropriate system parameters under certain conditions.

Food preservation by ionising radiation

International Nuclear Information System (INIS)

Andrade, M. E.

1996-01-01

The process of food preservation by ionising radiation is an alternative, or a complement, to the traditional methods of heating, refrigerating, freezing or using chemical additives. The study and development of this technique has started on the beginning of the fifties but it is based on the radiation killing effect on micro-organisms discovered by the end of last century. Foodstuffs are treated in appropriate plants: isotopic facilities (gamma radiation) and accelerated electron beams produced by machines called accelerators. The FAO and WHO in close cooperation with the IAEA have played an important role on the development of the process and on the increment of the industrial application of food irradiation. Over the world there are about 37 countries trading foods treated by ionising radiation. However, governments have been slow to clear the utilization of this process. The main reason of this attitude is in general due to the fact that the advantages of the technique are not clearly understood. Therefore, the dissemination of the information could on one hand clarify who has to take decisions and on the other hand support the choice of those foods by the consumers. This is the unique way to dynamize the application of this process

Biological monitors for low levels of ionising radiation

Energy Technology Data Exchange (ETDEWEB)

Mohankumar, M N; Jeevanram, R K [Safety Research and Health Physics Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1996-12-31

The biological effects of high doses of ionising radiation are well understood and the methods of measurement of these doses well established. However the effects due to extremely low doses remain by and large uncertain. This is because of the fact that at such low doses no gross symptoms are seen. In fact, at these levels the occurrence of double strand breaks leading to the formation of chromosomal aberrations like dicentrics is rare and chances of mutation due to base damage are negligible. Hence neither chromosomal aberration studies nor mutational assays are useful for detecting doses of the order of a few milligray. Results of exhaustive work done by various laboratories indicate that below 20 mGy the chromosomal aberration technique based on scoring of dicentrics cannot distinguish between a linear or a threshold model. However indirect methods like unscheduled DNA synthesis (UDS) and sister chromatid exchanges (SCEs) appear to be promising for the detection of radiation exposures due to low levels of radiation. This report reviews the available literature on the biological effects of low levels of ionising radiation and highlights the merits and demerits of the various methods employed in the measurement of UDS and SCE. The phenomenon of radio-adaptive response (RAR) and its relation to DNA repair is also discussed. (author). 98 refs., 11 figs., 4 tabs.

How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

Directory of Open Access Journals (Sweden)

X. Chen

2016-11-01

Full Text Available Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes such as clustering or attachment to pre-existing aerosol particles. This study aimed (1 to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, (2 to reveal the linkage between them and (3 to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003–2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Slightly similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8–1.7 nm in mobility diameters. However, features observed in the 0.8–1 nm ion concentration were in good connection to variations of the ionising capacity. Further, by carefully constraining perturbing variables, a strong dependency of the cluster ion concentration on the ionising capacity was identified, proving the functionality of ionising radiation in air ion production in the lower atmosphere. This relationship, however, was only clearly observed on new particle formation (NPF days, possibly indicating that charges after

Recent trends in utilising ionising radiations for nondestructive evaluation of materials (Preprint No. SP-3)

International Nuclear Information System (INIS)

Raj, Baldev; Venkatraman, B.

1988-02-01

The various NDT techniques based on the use of ionising radiations can be broadly classified into radiography, radiation gaging techniques and analytical techniques. This paper highlights the state of art of these techniques along with their applications. While an effort has been made to cover the major techniques based on ionising radiations, many techniques utilising ionising radiations as xeroradiography, laminography, ionography etc, have not been dealt with due to their restricted applications. (author). 23 refs., 4 figs

The potential use of ionising energy treatment in Queensland's horticultural industries

International Nuclear Information System (INIS)

Heather, N.W.; Sheehy, P.T.; Muirhead, I.F.; Brown, B.I.; Hassall, R.N.

1985-01-01

The potential application of ionising energy treatment technology in Queensland falls into three categories: insect disinfestation, disease control and quality improvement. The technology fulfils the requirements of a disinfestation treatment against Queensland fruit fly and other pests of quarantine importance in respect to efficacy, absence of phytotoxicity, absence of residues and, on technical considerations would be an ideal replacement for the fumigant EDB. The report examines the purposes of ionising energy treatment, economic and marketing aspects and research needs

Ionising radiation risk disclosure: When should radiographers assume a duty to inform?

Science.gov (United States)

Younger, C W E; Douglas, C; Warren-Forward, H

2018-05-01

Autonomy is a fundamental patient right for ethical practice, and informed consent is the mechanism by which health care professionals ensure this right has been respected. The ethical notion of informed consent has evolved alongside legal developments. Under Australian law, a provider who fails to disclose risk may be found to be in breach of a duty of disclosure, potentially facing legal consequences if the patient experiences harm that is attributable to an undisclosed risk. These consequences may include the common law tort of negligence. Ionising radiation, in the form of a medical imaging examination, has the potential to cause harm. However, stochastic effects cannot be attributable to a specific ionising radiation event. What then is the role of the Australian medical imaging service provider in disclosing ionising radiation risk? The ethical and legal principles of informed consent, and the duty of information provision to the patient are investigated. These general principles are then applied to the specific and unusual case of ionising radiation, and what responsibilities apply to the medical imaging provider. Finally, the legal, professional and ethical duties of the radiographer to disclose information to their patients are investigated. Australian law is unclear as to whether a radiographer has a common law responsibility to disclose radiation risk. There is ambiguity as to whether stochastic ionising radiation risk could be considered a legal disclosure responsibility. While it is unlikely that not disclosing risk will have medicolegal consequences, doing so represents sound ethical practice. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Ionising radiation safety training in the Australian Defence Organisation (ADO)

International Nuclear Information System (INIS)

Jenks, G.J.; O'Donovan, E.J.B.; Wood, W.B.

1998-01-01

Training personnel in ionising radiation safety within the Australian Defence Organisation (ADO) requires addressing some unique features of an organisation employing both military and civilian personnel. Activities may include those of a civil nature (such as industrial and medical radiography), specific military requirements (for training and emergency response) and scientific research and development. Some personnel may be assigned to full-time duties associated with radiation. However, most are designated as radiation protection officers as a secondary duty. A further complication is that most military personnel are subjected to postings at regular intervals. The ADO's Directorate of Defence Occupational Health and Safety has established an Ionising Radiation Safety Subcommittee to monitor not only the adequacy of the internal Ionising Radiation Safety Manual but also the training requirements. A Training Course, responding to these requirements, has been developed to emphasize, basic radiation theory and protection, operation of radiation monitors available in the ADO, an understanding of the Ionising Radiation Safety Manual, day-to-day radiation safety in units and establishments, and appropriate responses to radiation accidents and emergencies. In addition, students are briefed on a limited number of peripheral topics and participate in some site visits. Currently, two Courses are held annually, each with about twenty students. Most of the material is presented by ADO personnel with external contractor support. The three Courses held to date have proved successful, both for the students and the ADO generally. To seek national accreditation of the course through the Australian National Training Authority, as a first step, competency standards have been proposed. (authors)

The use of caffeine to assess high dose exposures to ionising radiation by dicentric analysis

International Nuclear Information System (INIS)

Pujol, M.; Puig, R.; Caballin, M. R.; Barrios, L.; Barquinero, J. F.

2012-01-01

Dicentric analysis is considered as a 'gold standard' method for biological dosimetry. However, due to the radiation-induced mitotic delay or inability to reach mitosis of heavily damaged cells, the analysis of dicentrics is restricted to doses up to 4-5 Gy. For higher doses, the analysis by premature chromosome condensation technique has been proposed. Here, it is presented a preliminary study is presented in which an alternative method to analyse dicentrics after high dose exposures to ionising radiation (IR) is evaluated. The method is based on the effect of caffeine in preventing the G2/M checkpoint allowing damaged cells to reach mitosis. The results obtained indicate that the co-treatment with Colcemide and caffeine increases significantly increases the mitotic index, and hence allows a more feasible analysis of dicentrics. Moreover in the dose range analysed, from 0 to 15 Gy, the dicentric cell distribution followed the Poisson distribution, and a simulated partial-body exposure has been clearly detected. Overall, the results presented here suggest that caffeine has a great potential to be used for dose-assessment after high dose exposure to IR. (authors)

Highly Dense Isolated Metal Atom Catalytic Sites

DEFF Research Database (Denmark)

Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei

2015-01-01

-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation......Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X...

Health protection of persons occupationally exposed to ionising radiation in Croatia

International Nuclear Information System (INIS)

Zavalic, M.

2005-01-01

The aim of this study was to investigate the health condition of workers occupationally exposed to ionising radiation. The results for 1406 workers exposed to ionising radiations, who were regularly examined in 2004, were analysed using Statistica 5.0. The analysis included workers' case histories, frequency of illnesses and causes of temporary or permanent work disability. Of 1406 workers, 16 (1.13%) were found permanently disabled; in 11 the cause of disability was lens opacity, in 2 persistent trombocitophenia, and in 2 malignant tumour. Twenty-four workers were temporarily disabled, of whom 5 due to pregnancy. Thrombocytopenia was found in 12 men and only one woman. Anaemia was found in 4 women; dicentric chromosomes were the cause of temporary disability in one person, and tuberculosis in one person. Medical examinations of Croatian workers confirm low occupational exposure to ionising radiation. With this type of radiation, the established lens impairments could not be characterised as occupational. The two malignant tumours however were recognised as occupational diseases.(author)

Complex systems of biological interest stability under ionising radiations

International Nuclear Information System (INIS)

Maclot, Sylvain

2014-01-01

This PhD work presents the study of stability of molecular systems of biological interest in the gas phase after interaction with ionising radiations. The use of ionising radiation can probe the physical chemistry of complex systems at the molecular scale and thus consider their intrinsic properties. Beyond the fundamental aspect, this work is part of the overall understanding of radiation effects on living organisms and in particular the use of ionizing radiation in radiotherapy. Specifically, this study focused on the use of low-energy multiply charged ions (tens of keV) provided by the GANIL (Caen), which includes most of the experiments presented. In addition, experiments using VUV photons were also conducted at synchrotron ELETTRA (Trieste, Italy). The bio-molecular systems studied are amino acids and nucleic acid constituents. Using an experimental crossed beams device allows interaction between biomolecules and ionising radiation leads mainly to the ionization and fragmentation of the system. The study of its relaxation dynamics is by time-of-flight mass spectrometry coupled to a coincidences measurements method. It is shown that an approach combining experiment and theory allows a detailed study of the fragmentation dynamics of complex systems. The results indicate that fragmentation is generally governed by the Coulomb repulsion but the intramolecular rearrangements involve specific relaxation mechanisms. (author) [fr

Erich Regener and the ionisation maximum of the atmosphere

Science.gov (United States)

Carlson, P.; Watson, A. A.

2014-12-01

In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

Highly charged atomic physics at HIRFL-CSR

International Nuclear Information System (INIS)

Ma Xinwen; Wang Youde; Hou Mingdong; Jin Gengmin

1996-01-01

HIRFL-CSR is a proposed electron cooling storage ring optimized to accelerate and store beams of highly charged heavy ions. Several possibilities for advanced atomic physics studies are discussed, such as studies of electron-ion, ion-atoms, photon-ion-electron interactions and high resolution spectroscopy

Analysis of the quasi-continuum band emitted by highly ionised tungsten atoms in the 4-7 nm range

International Nuclear Information System (INIS)

Madeira, T.I.; Amorim, P.; Marques, J.P.; Parente, F.; Indelicato, P.

2013-01-01

For the next upcoming generation of fusion experiments, such as ITER,Tungsten has been chosen as the materials for plasma facing components. Spectra emitted by highly ionized tungsten atoms from magnetically confined plasmas show a common feature: a narrow structured quasi-continuum emission band most prominent in the range 4-7 nm, which accounts for 40-80% of the radiated power. This band has been fairly well explained by unresolved transitions from groups 4d-4p, 4f-4d (Δn = 0) and 5d-4f, 5g-4f and 5p-4d (Δn = 1). In this work we use a Multi-Configuration Dirac-Fock code in Breit self-consistent field mode to compute level energies and transition probabilities for W 27+ to W 37+ ions contributing to this emission band. Intra-shell correlation was introduced in the calculation for both initial and final states and all dipole and quadrupole radiative transitions have been considered. The wavefunctions in the initial and final states are optimized separately and the resulting non-orthogonality effect is fully taken into account. The importance of some satellite lines was assessed. Together with the ionic distributions obtained by using the FLYCHK application and assuming that the initial states population depends statistically on the temperature we were able to synthesize plasma emission spectrum profiles for several electron temperatures. (authors)

Occupational Exposure to Ionising Radiation in Greece (1994-1998)

International Nuclear Information System (INIS)

Kamenopoulou, V.; Drikos, G.; Dimitriou, P.

2000-01-01

This study was scheduled in order to analyse the individual annual dose information on classified workers in Greece, monitored and assessed by the central dosimetry service at the Greek Atomic Energy Commission for the years 1994-98. This service provides film badges to about 7500 workers all over the country on a monthly basis. Dose summaries were recorded and processed by the Dose Registry Information System, the database of which has been totally renewed since 1994. The statistical analysis provided refers to and deals with the mean annual dose, the collective dose, the distribution of the dose over the different specialities and the number of workers that have exceeded any of the established dose levels. Results concerning the annual dose summaries demonstrate a decrease in the collective and the mean individual dose to workers in the year 1995 and a slight but steady year-by-year increase thereafter during the period under consideration. This increasing tendency is discussed along with the increase in the ionising radiation applications, especially those in the medical sector, the change of the positioning of the film badge and the quality control measures provided by Greek law for radiation laboratories. (author)

High speed atom source

International Nuclear Information System (INIS)

Hoshino, Hitoshi.

1990-01-01

In a high speed atom source, since the speed is not identical between ions and electrons, no sufficient neutralizing effect for ionic rays due to the mixing of the ionic rays and the electron rays can be obtained failing to obtain high speed atomic rays at high density. In view of the above, a speed control means is disposed for equalizing the speed of ions forming ionic rays and the speed of electrons forming electron rays. Further, incident angle of the electron rays and/or ionic rays to a magnet or an electrode is made variable. As a result, the relative speed between the ions and the electrons to the processing direction is reduced to zero, in which the probability of association between the ions and the electrons due to the coulomb force is increased to improve the neutralizing efficiency to easily obtain fine and high density high speed electron rays. Further, by varying the incident angle, a track capable of obtaining an ideal mixing depending on the energy of the neutralized ionic rays is formed. Since the high speed electron rays has such high density, they can be irradiated easily to the minute region of the specimen. (N.H.)

The ENEA calibration service for ionising radiations

International Nuclear Information System (INIS)

Monteventi, F.; Sermenghi, I.

1999-01-01

The report describes all the facilities available at the the service of the ENEA Calibration Service for Ionising Radiations at Bologna (Italy). It gives a detailed description of all equipments qualified for photon fields metrology including the secondary standards and the calibration procedures performed for radiation monitoring devices and dosemeters [it

Use of voltammetry for in vitro equilibrium and transport studies of ionisable drugs

Directory of Open Access Journals (Sweden)

Matej Velicky

2014-09-01

Full Text Available In this review, we will briefly outline the voltammetric investigations of the transfer of ionisable drugs at the interface between two immiscible electrolyte solutions. The voltammetric techniques enable the determination of some key in vitro properties of ionisable drugs, including partition coefficient, diffusion coefficient and membrane permeability. Some successful applications will be highlighted, together with the background methodologies.

Effects of intense stratospheric ionisation events

International Nuclear Information System (INIS)

Reid, G.C.; McAfee, J.R.; Crutzen, P.J.

1978-01-01

High levels of ionising radiation in the Earth's stratosphere will lead to increased concentrations of nitrogen oxides and decreased concentrations of ozone. Changes in the surface environment will include an increased level, of biologically harmful UV radiation, caused by the ozone depletion, and a decreased level of visible solar radiation, due to the presence of major enhancements in the stratospheric concentration of nitrogen dioxide. These changes have been studied quantitatively, using the passage of the Solar System through a supernova remnant shell as an example. Some of the potential environmental changes are a substantial global cooling, abnormally dry conditions, a reduction in global photosynthesis and a large increase in the flux of atmospheric fixed nitrogen to the surface of the Earth. Such events might have been the cause of mass extinctions in the distant past. (Author)

Cost considerations for an ionising energy treatment facility

International Nuclear Information System (INIS)

Culpitt, R.A.

1985-01-01

Variables influencing the cost of food irradiation can be included under three broad headings: the physical characteristics of products to be treated; the operational characteristics of the plant to be used; costs of establishment and operation of an ionising energy treatment

Tumour induction by small doses of ionised radiation

International Nuclear Information System (INIS)

Putten, L.M. van

1980-01-01

The effect of low doses of ionised radiation on tumour induction in animals is discussed. It is hypothesised that high doses of radiation can strongly advance tumour induction from the combination of a stimulated cell growth, as a reaction to massive cell killing, and damage to DNA in the cell nuclei. This effect has a limit below which the radiation dose causes a non-significant amount of dead cells. However in animals where through other reasons, a chronic growth stimulation already exists, only one effect, the damage of DNA, is necessary to induce tumours. A linear dose effect without a threshold level applies in these cases. Applying this hypothesis to man indicates that calculating low dose effects by linear extrapolation of high dose effects is nothing more than a reasonable approximation. (C.F.)

Detector for atomic particles and ionizing radiations

International Nuclear Information System (INIS)

Mallet, Georges; Ythier, Christian.

1976-01-01

The aim of this invention is to provide improved detectors of atomic particles and of ionising radiations, having maximum sensitivity, by virtually suppressing all absorption of the radiation scattered by the main detector, so that these detectors are particularly suitable for fitting to anti-Compton spectrometers. Reference is particularly made to detectors of the Ge(Li) type, lithium compensated germanium, which are the most used. It is however made clear that this choice is not restrictive and that this invention not only applies to all known types of detectors and particularly to scintillator detectors, for instance to detectors such as NaI (Tl), composed of a monocrystal of a thallium activated alkaline halogenide, but also to gas, ionisation chamber and luminescent chamber type detectors and in general to all the known devices that convert the energy of particles into electric signals. Owing to the fact that the walls of the enclosure containing the main detector are composed, in the part around this detector, of an auxiliary detector, the latter detects virtually all the radiations scattered by the main detector. It does so without any loss due to the absorption of these radiations (a) by the metal walls of the enclosure usually containing the main detector and (b) by the walls of the auxiliary detector casing. It results from this that the detectors of the invention enable coincidence or anti-coincidence spectrometers with a very high performance to be made [fr

Biological Effects of Ionising Radiation and Countermeasures (Les effets biologiques des rayonnements ionisants et leurs contre-mesures)

Science.gov (United States)

2018-01-01

radiation physicists. As an example, a special issue of Health Physics [3] presents a body of experimental work characterizing the outdoor...Terrorist Attack involving Ionising Radiation. Campus Vesta, Belgium September 25-29, 2016. [3] Health Physics (Special Issue) 2016:110;399- 547...of Radiobiology & Radiation Protection 128 Szaserów Street 04-141 Warsaw POLAND Email: mjaniak@wihe.waw.pl Mr. Tjerk KUIPERS Health Physics

A Compact, High-Flux Cold Atom Beam Source

Science.gov (United States)

Kellogg, James R.; Kohel, James M.; Thompson, Robert J.; Aveline, David C.; Yu, Nan; Schlippert, Dennis

2012-01-01

The performance of cold atom experiments relying on three-dimensional magneto-optical trap techniques can be greatly enhanced by employing a highflux cold atom beam to obtain high atom loading rates while maintaining low background pressures in the UHV MOT (ultra-high vacuum magneto-optical trap) regions. Several techniques exist for generating slow beams of cold atoms. However, one of the technically simplest approaches is a two-dimensional (2D) MOT. Such an atom source typically employs at least two orthogonal trapping beams, plus an additional longitudinal "push" beam to yield maximum atomic flux. A 2D atom source was created with angled trapping collimators that not only traps atoms in two orthogonal directions, but also provides a longitudinal pushing component that eliminates the need for an additional push beam. This development reduces the overall package size, which in turn, makes the 2D trap simpler, and requires less total optical power. The atom source is more compact than a previously published effort, and has greater than an order of magnitude improved loading performance.

Student and intern awareness of ionising radiation exposure from common diagnostic imaging procedures

International Nuclear Information System (INIS)

Zhou, G. Z.; Wong, D. D.; Nguyen, L. K.; Mendelson, R. M.

2010-01-01

Full text: This study aims to evaluate medical student and intern awareness of ionising radiation exposure from common diagnostic imaging procedures and to suggest how education could be improved. Fourth to sixth year medical students enrolled at a Western Australian university and interns from three teaching hospitals in Perth were recruited. Participants were asked to complete a questionnaire consisting of 26 questions on their background, knowledge of ionising radiation doses and learning preferences for future teaching on this subject. A total of 331 completed questionnaires were received (95.9%). Of the 17 questions assessing knowledge of ionising radiation, a mean score of 6.0 was obtained by respondents (95% CI 5.8-6.2). Up to 54.8% of respondents underestimated the radiation dose from commonly requested radiological procedures. Respondents (11.3 and 25.5%) incorrectly believed that ultrasound and MRI emit ionising radiation, respectively. Of the four subgroups of respondents, the intern doctor subgroup performed significantly better (mean score 6.9, P< 0.0001, 95% CI 6.5-7.3) than each of the three medical student subgroups. When asked for the preferred method of teaching for future radiation awareness, a combination of lectures, tutorials and workshops was preferred. This study has clearly shown that awareness of ionising radiation from diagnostic imaging is lacking among senior medical students and interns. The results highlight the need for improved education to minimise unnecessary exposure of patients and the community to radiation. Further studies are required to determine the most effective form of education.

Fallout: Hedley Marston and atomic bomb tests in Australia

International Nuclear Information System (INIS)

Cross, R.T.

2001-01-01

This book tells the story of Australian scientists involved in the 1956 British atomic tests at Maralinga. The story involves several of the country's most respected and trusted scientists of the 1950s and spills over to the scientific organisations that mattered. As the drama unfolds we see how the controversy touched the lives of many senior Australian scientists, and in a few cases those of British scientists, too. What is described in this book, however, is more than an esoteric scientific dispute kept within laboratory walls; it is a story about the nature of science in relation to society that continues into the present day. This controversy was, and is, about the health effects of low-level ionising radiation. There is still, after all these years, intense debate about the health effects of low-level ionising radiation to which from time to time most Australians are exposed through the dental and medical industry

RF System for the MICE Demonstration of Ionisation Cooling

Energy Technology Data Exchange (ETDEWEB)

Ronald, K.; et al.

2017-04-01

Muon accelerators offer an attractive option for a range of future particle physics experiments. They can enable high energy (TeV+) high energy lepton colliders whilst mitigating the difficulty of synchrotron losses, and can provide intense beams of neutrinos for fundamental physics experiments investigating the physics of flavor. The method of production of muon beams results in high beam emittance which must be reduced for efficient acceleration. Conventional emittance control schemes take too long, given the very short (2.2 microsecond) rest lifetime of the muon. Ionisation cooling offers a much faster approach to reducing particle emittance, and the international MICE collaboration aims to demonstrate this technique for the first time. This paper will present the MICE RF system and its role in the context of the overall experiment.

Investigation of damage mechanism by ionising radiation on biomolecules

International Nuclear Information System (INIS)

Lau How Mooi

1996-01-01

Occupational radiation hazard is a very controversial subject. Effects from high radiation doses are well known from past experiences. However, hazard from low doses is still a subject that is hotly debated upon until now. The occupational dosimetry used now is based on a macroscopic scale. Lately, microdosimetry is fast gaining recognition as a more superior way of measuring hazard. More importantly, scientists are researching the basic damage mechanism that leads to biological effects by ionising radiation. In this report, a simulation study of the basic damage mechanism is discussed . This simulation is based upon Monte Carlo calculations and using polyuridylic acid (Poly-U) as the DNA model This simulation tries to relate the physics and chemistry of interactions of ionising radiation with biomolecules. The computer codes used in this simulation, OREC and RADLYS were created by Hamm et al. (1983) in Oak Ridge National Laboratory. The biological endpoints in this simulation are the strand break and base release of the DNA, which is the precursor of all biological effects. These results are compared with model studies that had been done experimentally to check the validity of this simulation. The G-values of strand break and base release from this simulation were -2.35 and 2.75 and compared well with results from irradiation experiments by von Sonntag (I 98 7) from Max Plank's Institute, Germany

Fission ionisation chamber for the measurement of low fluxes of slow neutrons

International Nuclear Information System (INIS)

Weill, J.; Duchene, J.P.

1958-01-01

The ionisation chamber described is designed for the measurement of slow neutron fluxes of average or low intensity, in the presence, eventually, of very high gamma fluxes. The capture of a slow neutron by a fissile material, in this case 235 U, gives rise to fission fragments, high-energy particles which ionise the gas contained in the chamber. The neutrons are detected by virtue of the potential pulses, on the collecting electrode of the chamber, deriving from the collection of the ions produced by the fission fragments. The pulses are counted by means of a measuring system consisting of a preamplifier, a 2 Mc amplifier, a discriminator and an electronic scale with numerator or integrator. The general characteristics are as follows: sensitivity to neutrons: 0.07 kicks/n/cm 2 .s, sensitivity to γ rays: zero up to 3.10 4 R/H, a background noise at the normal discrimination voltage: 0.01 kicks/s, working H.T.: -500 V, capacity: 40 μμF, average height of pulse: 8 mV, limits of use: from several neutrons to 10 6 n/cm 2 .s. This chamber may be used in all cases where low fluxes of slow neutrons must be measured, especially in the presence of high gamma fluxes, for example in the checking of Pu concentrations in an extraction plant or for the starting up of reactors. (author) [fr

Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents

Energy Technology Data Exchange (ETDEWEB)

Weill, J; Duchene, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The ionisation chamber described is designed for the measurement of slow neutron fluxes of average or low intensity, in the presence, eventually, of very high gamma fluxes. The capture of a slow neutron by a fissile material, in this case {sup 235}U, gives rise to fission fragments, high-energy particles which ionise the gas contained in the chamber. The neutrons are detected by virtue of the potential pulses, on the collecting electrode of the chamber, deriving from the collection of the ions produced by the fission fragments. The pulses are counted by means of a measuring system consisting of a preamplifier, a 2 Mc amplifier, a discriminator and an electronic scale with numerator or integrator. The general characteristics are as follows: sensitivity to neutrons: 0.07 kicks/n/cm{sup 2}.s, sensitivity to {gamma} rays: zero up to 3.10{sup 4} R/H, a background noise at the normal discrimination voltage: 0.01 kicks/s, working H.T.: -500 V, capacity: 40 {mu}{mu}F, average height of pulse: 8 mV, limits of use: from several neutrons to 10{sup 6} n/cm{sup 2}.s. This chamber may be used in all cases where low fluxes of slow neutrons must be measured, especially in the presence of high gamma fluxes, for example in the checking of Pu concentrations in an extraction plant or for the starting up of reactors. (author) [French] La chambre d'ionisation decrite est destinee a la mesure des flux de neutrons lents d'intensite moyenne ou faible, en presence eventuelle de flux gamma tres importants. La capture d'un neutron lent par un materiau fissile, en l'occurrence {sup 235}U, donne naissance a des fragments de fission, particules de grande energie qui ionisent le gaz contenu dans la chambre. Les neutrons sont detectes grace aux impulsions de potentiel, sur l'electrode collectrice de la chambre, provenant de la collection des ions produits par les fragments de fission. Une chaine de mesure comprenant un preamplificateur, un amplificateur 2 Mc, un discriminateur, une echelle

Diseases induced by ionising radiation

International Nuclear Information System (INIS)

1984-11-01

An interim report is presented by the Industrial Injuries Advisory Council in accordance with Section 141 of the Social Security Act 1975 on the question whether the terms of prescription for occupational diseases induced by ionising radiation should be amended to cover a wider range of conditions. A lack of persuasive statistical data has prevented reliable estimates of health risks of radiation workers in the UK to be made. However the report gives details of the progress made so far and the difficulties encountered. (U.K.)

Atomic physics at high brilliance synchrotron sources: Proceedings

International Nuclear Information System (INIS)

Berry, G.; Cowan, P.; Gemmell, D.

1994-08-01

This report contains papers on the following topics: present status of SPring-8 and the atomic physics undulator beamline; recent photoabsorption measurements in the rare gases and alkalis in the 3 to 15 keV proton energy region; atomic and molecular physics at LURE; experiments on atoms, ions and small molecules using the new generation of synchrotron radiation sources; soft x-ray fluorescence spectroscopy using tunable synchrotron radiation; soft x-ray fluorescence spectroscopy excited by synchrotron radiation: Inelastic and resonant scattering near threshold; outer-shell photoionization of ions; overview of the APS BESSRC beamline development; the advanced light source: Research opportunities in atomic and molecular physics; Photoionization of the Ba + ion by 4d shell excitation; decay dynamics of inner-shell excited atoms and molecules; absorption of atomic Ca, Cr, Mn and Cu; High-resolution photoelectron studies of resonant molecular photoionization; radiative and radiationless resonant raman scattering by synchrotron radiation; auger spectrometry of atoms and molecules; some thoughts of future experiments with the new generation of storage rings; Electron spectroscopy studies of argon K-shell excitation and vacancy cascades; ionization of atoms by high energy photons; ion coincidence spectroscopy on rare gas atoms and small molecules after photoexcitation at energies of several keV; an EBIS for use with synchrotron radiation photoionization of multiply charged ions and PHOBIS; gamma-2e coincidence measurements the wave of the future in inner-shell electron spectroscopy; recoil momentum spectroscopy in ion-atom and photon-atom collisions; a study of compton ionization of helium; future perspectives of photoionization studies at high photon energies; and status report on the advanced photon source. These papers have been cataloged separately elsewhere

Medical use of ionising radiation - challenges for the third millennium

International Nuclear Information System (INIS)

Leitz, W.

2003-01-01

From the very beginning after its discovery ionising radiation has been in beneficial use for health care. But even the drawbacks showed up very early: only a few months after Roentgens discovery reports were published on patients who got severe skin damage after fluoroscopy with x-rays. This finding of the adverse effects was soon turned into something positive: ionising radiation could be used for treatment of cancer. In 1928 radiologists took the initiative to the foundation of what later became the International Commission on Radiological Protection, ICRP. Medical use of ionising radiation is giving by far the largest contribution to the radiation burden of the global population from artificial sources, on average 0,3 mSv per year and inhabitant, excluding doses from radiation treatment. In the Nordic countries this dose is approximately 0,7 mSv. This isn't a problem by itself. The total benefit is exceeding the total radiation risk with large margins. But the margins could even be larger. Methods for examinations and treatments have often a potential for improvements, meaning that the medical effect can be obtained with a lower dose to the patient. In certain circumstances the examination does not contribute to the further treatment of the patient or to her/his well-being and is then regarded as not justified. The huge challenge we are facing depends among other things on the extreme fast technical development which enables exposures of a magnitude that we haven't seen before and applications we only could dream about. There is a risk that the motto 'do what is possible to do' is followed instead of 'do what the individual patient needs'. This presentation addresses the possibilities, but also the dangers that medical use of ionising radiation in medical care is facing in the new millennium, or at least in its first years. (orig.)

Full Ionisation In Binary-Binary Encounters With Small Positive Energies

Science.gov (United States)

Sweatman, W. L.

2006-08-01

Interactions between binary stars and single stars and binary stars and other binary stars play a key role in the dynamics of a dense stellar system. Energy can be transferred between the internal dynamics of a binary and the larger scale dynamics of the interacting objects. Binaries can be destroyed and created by the interaction. In a binary-binary encounter, full ionisation occurs when both of the binary stars are destroyed in the interaction to create four single stars. This is only possible when the total energy of the system is positive. For very small energies the probability of this occurring is very low and it tends towards zero as the total energy tends towards zero. Here the case is considered for which all the stars have equal masses. An asymptotic power law is predicted relating the probability of full ionisation with the total energy when this latter quantity is small. The exponent, which is approximately 2.31, is compared with the results from numerical scattering experiments. The theoretical approach taken is similar to one used previously in the three-body problem. It makes use of the fact that the most dramatic changes in scale and energies of a few-body system occur when its components pass near to a central configuration. The position, and number, of these configurations is not known for the general four-body problem, however, with equal masses there are known to be exactly five different cases. Separate consideration and comparison of the properties of orbits close to each of these five central configurations enables the prediction of the form of the cross-section for full ionisation for the case of small positive total energy. This is the relation between total energy and the probability of total ionisation described above.

Fully kinetic simulations of magnetic reconnection in partially ionised gases

Science.gov (United States)

Innocenti, M. E.; Jiang, W.; Lapenta, G.; Markidis, S.

2016-12-01

Magnetic reconnection has been explored for decades as a way to convert magnetic energy into kinetic energy and heat and to accelerate particles in environments as different as the solar surface, planetary magnetospheres, the solar wind, accretion disks, laboratory plasmas. When studying reconnection via simulations, it is usually assumed that the plasma is fully ionised, as it is indeed the case in many of the above-mentioned cases. There are, however, exceptions, the most notable being the lower solar atmosphere. Small ionisation fractions are registered also in the warm neutral interstellar medium, in dense interstellar clouds, in protostellar and protoplanetary accreditation disks, in tokamak edge plasmas and in ad-hoc laboratory experiments [1]. We study here how magnetic reconnection is modified by the presence of a neutral background, i.e. when the majority of the gas is not ionised. The ionised plasma is simulated with the fully kinetic Particle-In-Cell (PIC) code iPic3D [2]. Collisions with the neutral background are introduced via a Monte Carlo plug-in. The standard Monte Carlo procedure [3] is employed to account for elastic, excitation and ionization electron-neutral collisions, as well as for elastic scattering and charge exchange ion-neutral collisions. Collisions with the background introduce resistivity in an otherwise collisionless plasma and modifications of the particle distribution functions: particles (and ions at a faster rate) tend to thermalise to the background. To pinpoint the consequences of this, we compare reconnection simulations with and without background. References [1] E E Lawrence et al. Physical review letters, 110(1):015001, 2013. [2] S Markidis et al. Mathematics and Computers in Simulation, 80(7):1509-1519, 2010. [3] K Nanbu. IEEE Transactions on plasma science, 28(3):971-990, 2000.

Synthetic diamond devices for radiotherapy applications: Thermoluminescent dosimeter and ionisation chamber

International Nuclear Information System (INIS)

Descamps, C.; Tromson, D.; Mer, C.; Nesladek, M.; Bergonzo, P.

2006-01-01

In radiotherapy field, the major usage of dosimeters is in the measurement of the dose received by the patient during radiotherapy (in-vivo measurements) and in beam calibration and uniformity checks. Diamond exhibits several interesting characteristics that make it a good candidate for radiation detection. It is indeed soft-tissue equivalent (Z=6 compared to Z=7.42 for human tissue), mechanically robust and relatively insensitive to radiation damage, chemically stable and non toxic. Moreover, the recent availability of synthetic samples, grown under controlled conditions using the chemical vapour deposition (C.V.D.) technique, allowed decreasing the high cost and the long delivery time of diamond devices. Diamond can be use for off-line dosimetry as thermoluminescent dosimeters or for on-line dosimetry as ionisation chamber [2,3]. These both applications are reported here. For this study, samples were grown in the laboratory and devices were then tested under X-ray irradiations and in clinical environment under medical cobalt source. The work described in this paper was performed in the framework of the European Integrated Project M.A.E.S.T.R.O., Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology, (6. FP) which is granted by the European Commission.The first results of this study clearly show that C.V.D. diamond detectors are suitable for dosimetry in radiotherapy applications. Moreover, for both T.L. dosimeters and ionisation chambers applications, and even though the sensitivity is subsequently reduced, nitrogen incorporation in films seems to significantly improve the dosimetric characteristics of the devices. Therefore, the optimisation of the material quality appears as a very important issue in order to increase the dosimetric characteristics of devices and more particularly, for use as thermoluminescent dosimeters, other impurities (Nickel, Phosphorus) will be tested. For ionisation chamber applications, experiments with

Use of ionising radiation in the teaching of physics and chemistry

International Nuclear Information System (INIS)

2000-01-01

The guide lays down the safety requirements for the use of radiation in school education, as well as the principles regulating the use of radiation sources without the safety licence referred to in section 16 of the Finnish Radiation Act (592/1991). The guide covers the use of radiation sources emitting ionising radiation in elementary schools and high schools, as well as the use of radiation in the teaching of physics and chemistry in vocational training institutions and corresponding educational institutions

Investigation of phosphorus atomization using high-resolution continuum source electrothermal atomic absorption spectrometry

International Nuclear Information System (INIS)

Dessuy, Morgana B.; Vale, Maria Goreti R.; Lepri, Fabio G.; Welz, Bernhard; Heitmann, Uwe

2007-01-01

The atomization of phosphorus in electrothermal atomic absorption spectrometry has been investigated using a high-resolution continuum source atomic absorption spectrometer and atomization from a graphite platform as well as from a tantalum boat inserted in a graphite tube. A two-step atomization mechanism is proposed for phosphorus, where the first step is a thermal dissociation, resulting in a fast atomization signal early in the atomization stage, and the second step is a slow release of phosphorus atoms from the graphite tube surface following the adsorption of molecular phosphorus at active sites of the graphite surface. Depending on experimental conditions only one of the mechanisms or both might be active. In the absence of a modifier and with atomization from a graphite or tantalum platform the second mechanism appears to be dominant, whereas in the presence of sodium fluoride as a modifier both mechanisms are observed. Intercalation of phosphorus into the graphite platform in the condensed phase has also been observed; this phosphorus, however, appears to be permanently trapped in the structure of the graphite and does not contribute to the absorption signal

Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

Science.gov (United States)

Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

2017-04-01

Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of R-Matrix with Time-dependence Theory to Double Ionisation Using a 2-electron Outer Region

International Nuclear Information System (INIS)

Wragg, Jack; Parker, J S; Van der Hart, H W

2015-01-01

R-Matrix with Time-dependence (RMT) theory has been extended to cover double-ionisation processes. An application to photoionisation of He is demonstrated, with an emphasis on double-ionisation cross sections. (paper)

Sputtering of copper atoms by keV atomic and molecular ions A comparison of experiment with analytical and computer based models

CERN Document Server

Gillen, D R; Goelich,

2002-01-01

Non-resonant multiphoton ionisation combined with quadrupole and time-of-flight analysis has been used to measure energy distributions of sputtered copper atoms. The sputtering of a polycrystalline copper target by 3.6 keV Ar sup + , N sup + and CF sub 2 sup + and 1.8 keV N sup + and CF sub 2 sup + ion bombardment at 45 deg. has been investigated. The linear collision model in the isotropic limit fails to describe the high energy tail of the energy distributions. However the TRIM.SP computer simulation has been shown to provide a good description. The results indicate that an accurate description of sputtering by low energy, molecular ions requires the use of computer simulation rather than analytical approaches. This is particularly important when considering plasma-surface interactions in plasma etching and deposition systems.

Impact ionisation mass spectrometry of polypyrrole-coated pyrrhotite microparticles

Science.gov (United States)

Hillier, Jon K.; Sternovsky, Zoltan; Armes, Steven P.; Fielding, Lee A.; Postberg, Frank; Bugiel, Sebastian; Drake, Keith; Srama, Ralf; Kearsley, Anton T.; Trieloff, Mario

2014-07-01

Cation and anion impact ionization mass spectra of polypyrrole-coated pyrrhotite cosmic dust analogue particles are analysed over a range of cosmically relevant impact speeds. Spectra with mass resolutions of 150-300 were generated by hypervelocity impacts of charged particles, accelerated to up to 37 km s-1 in a Van de Graaff electrostatic accelerator, onto a silver target plate in the Large Area Mass Analyzer (LAMA) spectrometer. Ions clearly indicative of the polypyrrole overlayer are identified at masses of 93, 105, 117, 128 and 141 u. Organic species, predominantly derived from the thin (20 nm) polypyrrole layer on the surface of the particles, dominate the anion spectra even at high (>20 km s-1) impact velocities and contribute significantly to the cation spectra at velocities lower than this. Atomic species from the pyrrhotite core (Fe and S) are visible in all spectra at impact velocities above 6 km s-1 for 56Fe+, 9 km s-1 for 32S+ and 16 km s-1 for 32S- ions. Species from the pyrrhotite core are also frequently visible in cation spectra at impact speeds at which surface ionisation is believed to dominate (Silver was confirmed as an excellent choice for the target plate of an impact ionization mass spectrometer, as it provided a unique isotope signature for many target-projectile cluster peaks at masses above 107-109 u. The affinity of Ag towards a dominant organic fragment ion (CN-) derived from fragmentation of the polypyrrole component led to molecular cluster formation. This resulted in an enhanced sensitivity to a particular particle component, which may be of great use when investigating astrobiologically relevant chemicals, such as amino acids.

Summary of informal meeting on ''facilities for atomic physics research with highly ionized atoms''

International Nuclear Information System (INIS)

Cocke, C.L.; Jones, K.W.

1984-01-01

An informal meeting to discuss ''Facilities for Atomic Physics Research with Highly Ionized Atoms'' was held during the APS DEAP meeting at the University of Connecticut on May 30, 1984. The meeting was motivated by the realization that the status of facilities for studies of highly ionized atoms is unsettled and that it might be desirable to take action to ensure adequate resources for research over the whole range of charge states and energies of interest. It was assumed that the science to be done with these beams has been amply documented in the literature

Atomic hydrogen effects on high-Tc superconductors

International Nuclear Information System (INIS)

Frantskevich, N.V.; Ulyashin, A.G.; Alifanov, A.V.; Stepanenko, A.V.; Fedotova, V.V.

1999-01-01

The atomic hydrogen effects on the properties of bulk high-temperature superconductors were investigated. It is shown that the insertion of the atomic hydrogen into the bulk of these materials from a DC plasma leads to the increase of the critical current density J c for YBaCuO(123) as well as for BiSrCaCuO(2223) high-temperature superconductors. It is found that the hydrogenation of the He implanted samples with following annealing leads to the optically detected blistering on the surface. It means that the textured thin subsurface layers of high-temperature superconductors can be formed by this method. The improvement of superconductivity by atomic hydrogen can be explained by the passivation of dangling bonds and defects on grain boundaries of these materials

Atomic motion in a high-intensity standing wave laser field

International Nuclear Information System (INIS)

Saez Ramdohr, L.F.

1987-01-01

This work discusses the effect of a high-intensity standing wave laser field on the motion of neutral atoms moving with a relatively high velocity. The analysis involves a detailed calculation of the force acting on the atoms and the calculation of the diffusion tensor associated with the fluctuations of the quantum force operator. The high-intensity laser field limit corresponds to a Rabi frequency much greater than the natural rate of the atom. The general results are valid for any atomic velocity. Results are then specialized to the case of slow and fast atoms where the Doppler shift of the laser frequency due to the atomic motion is either smaller or larger than the natural decay rate of the atom. The results obtained for the force and diffusion tensor are applied to a particular ideal experiment that studies the evolution of a fast atomic beam crossing a high-intensity laser beam. The theories developed previously, for a similar laser configuration, discuss only the low atomic velocities case and not the more realistic case of fast atoms. Here, an approximate solution of the equation for the distribution is obtained. Starting from the approximate distribution function, the deflection angle and dispersion angle for the atomic beam with respect to the free motion are calculated

Burn-up determination of irradiated thoria samples by isotope dilution-thermal ionisation mass spectrometry

International Nuclear Information System (INIS)

Aggarwal, S.K.; Jaison, P.G.; Telmore, V.M.; Shah, R.V.; Sant, V.L.; Sasibhushan, K.; Parab, A.R.; Alamelu, D.

2010-03-01

Burn-up was determined experimentally using thermal ionization mass spectrometry for two samples from ThO 2 bundles irradiated in KAPS-2. This involved quantitative dissolution of the irradiated fuel samples followed by separation and determination of Th, U and a stable fission product burn-up monitor in the dissolved fuel solution. Stable fission product 148 Nd was used as a burn-up monitor for determining the number of fissions. Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) using natural U, 229 Th and enriched 142 Nd as spikes was employed for the determination of U, Th and Nd, respectively. Atom % fission values of 1.25 ± 0.03 were obtained for both the samples. 232 U content in 233 U determined by alpha spectrometry was about 500 ppm and this was higher by a factor of 5 compared to the theoretically predicted value by ORIGEN-2 code. (author)

Health Services management. Health Service use of ionising radiations

International Nuclear Information System (INIS)

1989-12-01

This circular consolidates and updates advice on the statutory and management responsibilities of Health Authorities in relation to the use of ionising radiations (including radioactive substances) on premises controlled by them and/or by persons employed by them (author)

A new thermal ionisation mass spectrometer

International Nuclear Information System (INIS)

Haines, C.; Merren, T.O.; Unsworth, W.D.

1979-01-01

The Isomass 54E, a new thermal ionisation mass spectrometer for precise measurements of isotopic composition is described in detail. It combines the fruits of three development pro ects, viz. automation, energy filters and extended geometry with existing micromass expertise and experience. The hardware and software which are used for the automation as well as the energy filter used, are explained. The 'extended geometry' ion optical system adopted for better performance is discussed in detail. (K.B.)

Atomic physics with highly charged ions. Progress report

Energy Technology Data Exchange (ETDEWEB)

Richard, P.

1994-08-01

The study of inelastic collision phenomena with highly charged projectile ions and the interpretation of spectral features resulting from these collisions remain as the major focal points in the atomic physics research at the J.R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas. The title of the research project, ``Atomic Physics with Highly Charged Ions,`` speaks to these points. The experimental work in the past few years has divided into collisions at high velocity using the primary beams from the tandem and LINAC accelerators and collisions at low velocity using the CRYEBIS facility. Theoretical calculations have been performed to accurately describe inelastic scattering processes of the one-electron and many-electron type, and to accurately predict atomic transition energies and intensities for x rays and Auger electrons. Brief research summaries are given for the following: (1) electron production in ion-atom collisions; (2) role of electron-electron interactions in two-electron processes; (3) multi-electron processes; (4) collisions with excited, aligned, Rydberg targets; (5) ion-ion collisions; (6) ion-molecule collisions; (7) ion-atom collision theory; and (8) ion-surface interactions.

Additives in UV and ionising radiation grafting and curing processes

International Nuclear Information System (INIS)

Garnett, J.L.; Ng, L.T.; Viengkhou, V.

1998-01-01

Full text: Curing of polymers induced by both UV and ionising radiation are now established technologies. Currently both systems are predominantly based on acrylate chemistry. UV processes use photoinitiators to achieve fast polymerisation. In the proposed paper the significance of the occurrence of concurrent grafting with cure will be examined. particularly with respect to the recycling of finished product. Basic studies on grafting initiated by UV and ionising radiation will be discussed. Polar methyl methacrylate (MMA) and non-polar styrene will be used as representative monomers with cellulose and propylene typifying the backbone polymers. The additives chosen for examination in this study are predominantly components used in radiation curing formulations since grafting and curing are known to be mechanically related. The additives used were mineral acid, photoinitiators, vinyl ethers, oligomers, polyfunctional monomers including multifunctional acrylates (MFAs) and methacrylates (MFMAs). For the first time the use of charge transfer complexes in the Mulliken sense as additives in radiation grafting will be discussed. The CT complexes themselves, being monomers, have also been grafted to the above polymers. Recent developments with excimer laser sources for initiating these processes will be discussed, especially the use of non-acrylate chemistry. Excimer laser sources are shown to complement conventional UV and ionising radiation and are photoinitiator free. Mechanisms for the above grafting and curing processes will be outlined

S.I. No 125 of 2000 Radiological Protection Act 1991 (ionising radiation) Order 2000

International Nuclear Information System (INIS)

2000-01-01

This statutory instrument provides for the implementation of Council Directive 96/29/Euratom of 13 May 1996 laying down basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiation. It also incorporates the provisions of Council Directive 90/641/Euratom of 4 December 1990 on the operational protection of outside workers exposed to the risk of ionising radiation during their activities in controlled areas. It replaces the provisions of the European Communities (Ionising Radiation) Regulations, 1991 (S.I. No. 43 of 1991), the Radiological Protection Act, 1991 (General Control of Radioactive Substances, Nuclear Devices and Irradiating Apparatus) Order, 1993 (S.I. No. 151 of 1993) and the European Communities (Protection of Outside Workers from Ionising Radiation) Regulations, 1994 (S.I. No. 144 of 1994). The main changes introduced in this Order are: the inclusion of work activities involving exposure to natural sources of radiation, stricter application of existing radiation protection principles through the introduction of lower dose limits, the use of dose constraints in keeping doses as low as reasonably achievable (i.e. optimisation process) and extended application of justification principles, the introduction of radiation protection principles for intervention in cases of radiological emergencies or lasting exposures. (author)

NDT using ionising radiation in the Indian space programme

International Nuclear Information System (INIS)

Viswanathan, K.

1997-01-01

Ionising radiations continue to play a vital role in the Non-Destructive Evaluation (NDE) of various components used in space vehicles and satellites. The different Non-Destructive Testing (NDT) methods which are useful to the Indian space programme are discussed. 4 refs., 5 figs

European Communities (Foodstuffs treated with ionising radiation) Regulations, 2000. Statutory Instrument S.I. No. 297 of 2000

International Nuclear Information System (INIS)

2000-01-01

These Regulations give effect to Directive 1999/2/EC (the framework Directive) of the European Parliament and of the Council of 22 February 1999 on the approximation of the laws of the Member States concerning foods and food ingredients treated with ionising radiation and Directive 1999/3/EC (the implementing Directive) of the European Parliament and of the Council of 22 February 1999 on the establishment of a Community list of foods and food ingredients treated with ionising radiation. The effect of these Regulations is to lay down the general provisions for the treatment of foodstuffs with ionising radiation. Provisions concerning the approval and control of irradiation facilities and rules on labelling are also included. A positive list of foodstuffs authorised for treatment with ionising radiation and their maximum radiation doses are defined in the implementing Directive. These Regulations should be read together with the two Directives (author)

Medical response to effects of ionising radiation

International Nuclear Information System (INIS)

Crosbie, W.A.; Gittus, J.H.

1989-01-01

The proceedings of a conference on 'Medical Response to Effects of Ionising Radiation' in 1989 in the form of nineteen papers published as a book. Topics discussed include radiation accidents at nuclear facilities, the medical management of radiation casualties, the responsibilities, plans and resources for coping with a nuclear accident and finally the long term effects of radiation, including leukaemia epidemiology studies. All papers were selected and indexed separately. (UK)

Metabolite signal identification in accurate mass metabolomics data with MZedDB, an interactive m/z annotation tool utilising predicted ionisation behaviour 'rules'

Directory of Open Access Journals (Sweden)

Snowdon Stuart

2009-07-01

Full Text Available Abstract Background Metabolomics experiments using Mass Spectrometry (MS technology measure the mass to charge ratio (m/z and intensity of ionised molecules in crude extracts of complex biological samples to generate high dimensional metabolite 'fingerprint' or metabolite 'profile' data. High resolution MS instruments perform routinely with a mass accuracy of Results Metabolite 'structures' harvested from publicly accessible databases were converted into a common format to generate a comprehensive archive in MZedDB. 'Rules' were derived from chemical information that allowed MZedDB to generate a list of adducts and neutral loss fragments putatively able to form for each structure and calculate, on the fly, the exact molecular weight of every potential ionisation product to provide targets for annotation searches based on accurate mass. We demonstrate that data matrices representing populations of ionisation products generated from different biological matrices contain a large proportion (sometimes > 50% of molecular isotopes, salt adducts and neutral loss fragments. Correlation analysis of ESI-MS data features confirmed the predicted relationships of m/z signals. An integrated isotope enumerator in MZedDB allowed verification of exact isotopic pattern distributions to corroborate experimental data. Conclusion We conclude that although ultra-high accurate mass instruments provide major insight into the chemical diversity of biological extracts, the facile annotation of a large proportion of signals is not possible by simple, automated query of current databases using computed molecular formulae. Parameterising MZedDB to take into account predicted ionisation behaviour and the biological source of any sample improves greatly both the frequency and accuracy of potential annotation 'hits' in ESI-MS data.

Ionising energy treatment of fresh fruit

International Nuclear Information System (INIS)

Rigney, C.J.

1985-01-01

The main purposes of the ionising energy treatment of fresh fruit are: the extension of shelf life of the commodity due to a direct physiological effect on the particular product; the extension of shelf life of the commodity due to a reduction in the development of moulds and rots which would normally render the product worthless; and the killing of insect pests of quarantine significance, to allow for normal marketing of fresh fruit without the risk of introducing insect pests to previously pest-free areas

Experiments with Highly-Ionized Atoms in Unitary Penning Traps

Directory of Open Access Journals (Sweden)

Shannon Fogwell Hoogerheide

2015-08-01

Full Text Available Highly-ionized atoms with special properties have been proposed for interesting applications, including potential candidates for a new generation of optical atomic clocks at the one part in 1019 level of precision, quantum information processing and tests of fundamental theory. The proposed atomic systems are largely unexplored. Recent developments at NIST are described, including the isolation of highly-ionized atoms at low energy in unitary Penning traps and the use of these traps for the precise measurement of radiative decay lifetimes (demonstrated with a forbidden transition in Kr17+, as well as for studying electron capture processes.

Properties of an electret ionisation chamber for individual dosimetry in photon radiation fields

International Nuclear Information System (INIS)

Doerschel, B.; Pretzsch, G.

1985-01-01

The main properties of individual photon dosemeters are their energy and angular dependence and their measuring range and measurement accuracy. The determination of radiation exposure from the dosemeter readout is based on the choice of appropriate conversion factors, taking into account the influence of body backscatter on the dosemeter readout. The measurement range and accuracy of an electret ionisation chamber primarily depend on the electret stability and charge state measurement as well as on the chamber geometry. Dosimetric properties are described for an electret ionisation chamber designed for personnel monitoring. (author)

Ionising radiation and trans-generational instability

International Nuclear Information System (INIS)

Vrhovac, I.; Niksic, G.

2007-01-01

Indirect monitoring of the impact posed by ionising radiation to the genome instability of the descendants, consequent to the irradiation of one of their parents, boils down to the investigation of changes occurring exclusively in the mini-satellite loci of the cells constituting the gametal developmental line. The resultant mini-satellite mutations are expressed in their percentages, and equal to the ratio of the number of mutated alleles in that particular generation over the total number of alleles present. The impact of ionising radiation to the irradiated parent's offspring was first noticed on haematopoietic mouse stem-cells. Even though an irradiated cell of a female parent lacks any mutations whatsoever, daughter cells present with the increased mutation rates. The observed phenomenon of the so called trans-generational instability has been defined as the occurrence of mutations in the genome of individuals originating from the irradiated ancestors. Due to the aforementioned, one can conclude that these mutations need not be present in the irradiated parental cells, and do not necessarily vanish in the next few generations, but may result in the increase in mutation rates observed in the latter. The results of the investigations performed on the animal model, as well as of those carried out in human population, point to the occurrence of significant changes to be found on mini-satellite loci of the descending generation, while the mechanism underlying those changes hasn't been completely clarified yet, and, therefore, calls for the further investigation. (author)

Design and test of a scintillation dosimeter for dosimetry measurements of high energy radiotherapy beams; Conception et realisation d'un dosimetre a scintillation adapte a la dosimetrie de faisceaux de rayonnements ionisants en faisceaux de rayonnements ionisants en radiotherapie

Energy Technology Data Exchange (ETDEWEB)

Fontbonne, J.M

2002-12-01

This work describes the design and evaluation of the performances of a scintillation dosimeter developed for the dosimetry of radiation beams used in radiotherapy. The dosimeter consists in a small plastic scintillator producing light which is guided by means of a plastic optical fiber towards photodetectors. In addition to scintillation, high energy ionizing radiations produce Cerenkov light both in the scintillator and the optical fiber. Based on a wavelength analysis, we have developed a deconvolution technique to measure the scintillation light in the presence of Cerenkov light. We stress the advantages that are anticipated from plastic scintillator, in particular concerning tissue or water equivalence (mass stopping power, mass attenuation or mass energy absorption coefficients). We show that detectors based on this material have better characteristics than conventional dosimeters such as ionisation chambers or silicon detectors. The deconvolution technique is exposed, as well as the calibration procedure using an ionisation chamber. We have studied the uncertainty of our dosimeter. The electronics noise, the fiber transmission, the deconvolution technique and the calibration errors give an overall combined experimental uncertainty of about 0,5%. The absolute response of the dosimeter is studied by means of depth dose measurements. We show that absolute uncertainty with photons or electrons beams with energies ranging from 4 MeV to 25 MeV is less than {+-} 1 %. Last, at variance with other devices, our scintillation dosimeter does not need dose correction with depth. (author)

Nuclear recoil scintillation and ionisation yields in liquid xenon from ZEPLIN-III data

Energy Technology Data Exchange (ETDEWEB)

Horn, M., E-mail: m.horn@imperial.ac.uk [High Energy Physics group, Blackett Laboratory, Imperial College London (United Kingdom); Belov, V.A.; Akimov, D.Yu. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Araujo, H.M. [High Energy Physics group, Blackett Laboratory, Imperial College London (United Kingdom); Barnes, E.J. [School of Physics and Astronomy, SUPA University of Edinburgh (United Kingdom); Burenkov, A.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Chepel, V. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Currie, A. [High Energy Physics group, Blackett Laboratory, Imperial College London (United Kingdom); Edwards, B. [Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Ghag, C.; Hollingsworth, A. [School of Physics and Astronomy, SUPA University of Edinburgh (United Kingdom); Kalmus, G.E. [Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Kobyakin, A.S.; Kovalenko, A.G. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Lebedenko, V.N. [High Energy Physics group, Blackett Laboratory, Imperial College London (United Kingdom); Lindote, A. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Lopes, M.I. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Luescher, R.; Majewski, P. [Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Murphy, A.StJ. [School of Physics and Astronomy, SUPA University of Edinburgh (United Kingdom)

2011-11-24

Scintillation and ionisation yields for nuclear recoils in liquid xenon above 10 keV{sub nr} (nuclear recoil energy) are deduced from data acquired using broadband Am-Be neutron sources. The nuclear recoil data from several exposures to two sources were compared to detailed simulations. Energy-dependent scintillation and ionisation yields giving acceptable fits to the data were derived. Efficiency and resolution effects are treated using a light collection Monte Carlo, measured photomultiplier response profiles and hardware trigger studies. A gradual fall in scintillation yield below {approx}40 keV{sub nr} is found, together with a rising ionisation yield; both are in agreement with the latest independent measurements. The analysis method is applied to the most recent ZEPLIN-III data, acquired with a significantly upgraded detector and a precision-calibrated Am-Be source, as well as to the earlier data from the first run in 2008. A new method for deriving the recoil scintillation yield, which includes sub-threshold S1 events, is also presented which confirms the main analysis.

Ionisation and dissociation of water induced by swift multicharged ions; Etude de l'ionisation et de la dissociation d'H{sub 2}O induites par collision avec des ions multicharges rapides

Energy Technology Data Exchange (ETDEWEB)

Legendre, S

2006-02-15

Ionization and dissociation of water molecules and water clusters induced by 11.7 MeV/A Ni{sup 25+} ions were carried out by imaging techniques. Branching ratios, ionisation cross sections and Kinetic Energy Released distributions have been measured together with fragmentation dynamics studies. Multiple ionization represents approximately 30% of the ionizing events. Double ionization produces in significant way atomic oxygen, considered as a possible precursor of the large production of HO{sub 2} radical in liquid water radiolysis by ions of high Linear Energy Transfer. We evidence a strong selectivity of bond breakage in the case of ion-induced HOD fragmentation. Once the molecule doubly ionized, the breakage of the O-H bond is found 6.5 times more probable than that of the O-D bond. A semi-classical calculation simulating the fragmentation dynamics on the potential energy surface of the ground-state of di-cation H{sub 2}O{sup 2+} makes possible to as well reproduce the preferential nature of the breakage of the O-H bond as the position and the shift of the kinetic energy distributions. First results concerning interaction with water clusters are also reported. Measurements in coincidence are carried out giving access to correlation, with the distributions in energy and angle of the emitted fragments. Mass spectrum points fast intra-cluster proton transfer, leading to the emission of protonated clusters. (author)

Destruction of Raman biosignatures by ionising radiation and the implications for life detection on Mars.

Science.gov (United States)

Dartnell, Lewis R; Page, Kristian; Jorge-Villar, Susana E; Wright, Gary; Munshi, Tasnim; Scowen, Ian J; Ward, John M; Edwards, Howell G M

2012-04-01

Raman spectroscopy has proven to be a very effective approach for the detection of microorganisms colonising hostile environments on Earth. The ExoMars rover, due for launch in 2018, will carry a Raman laser spectrometer to analyse samples of the martian subsurface collected by the probe's 2-m drill in a search for similar biosignatures. The martian surface is unprotected from the flux of cosmic rays, an ionising radiation field that will degrade organic molecules and so diminish and distort the detectable Raman signature of potential martian microbial life. This study employs Raman spectroscopy to analyse samples of two model organisms, the cyanobacterium Synechocystis sp. PCC 6803 and the extremely radiation resistant polyextremophile Deinococcus radiodurans, that have been exposed to increasing doses of ionising radiation. The three most prominent peaks in the Raman spectra are from cellular carotenoids: deinoxanthin in D. radiodurans and β-carotene in Synechocystis. The degradative effect of ionising radiation is clearly seen, with significant diminishment of carotenoid spectral peak heights after 15 kGy and complete erasure of Raman biosignatures by 150 kGy of ionising radiation. The Raman signal of carotenoid in D. radiodurans diminishes more rapidly than that of Synechocystis, believed to be due to deinoxanthin acting as a superior scavenger of radiolytically produced reactive oxygen species, and so being destroyed more quickly than the less efficient antioxidant β-carotene. This study highlights the necessity for further experimental work on the manner and rate of degradation of Raman biosignatures by ionising radiation, as this is of prime importance for the successful detection of microbial life in the martian near subsurface.

Regulatory control and challenges in Medical facilities using ionising radiation sources

International Nuclear Information System (INIS)

Agarwal, S.P.

2008-01-01

Medical facilities utilising ionising radiation sources for diagnostic and treatment of cancer are regulated under the provisions of Atomic Energy (Radiation Protection) Rules, 2004 promulgated under the Atomic Energy Act 1962. The Competent Authority for the enforcement of the rules is Chairman, Atomic Energy Regulatory Board (AERB). Practice specific codes are issued by AERB for medical facilities such as Radiotherapy, Nuclear Medicine and Radiology. Regulatory process for control of medical facilities covers the entire life cycle of the radiation sources in three stages viz pre-Iicensing, during useful life and decommissioning and disposal. Pre-Iicensing requirements include use of type approved sources and equipment, approval of design layout of the facility and installation, exclusive (safe and secure) source storage facility when the equipment is not in use, radiation (area/individual) monitoring devices, qualified, trained and certified manpower, emergency response plans and commitment from the licensee for the safe disposal of disused/decayed sources. Compliance to these requirements makes the applicant eligible to obtain license from AERB for the operation of the medical facility. During the use of radiation sources, specific prior approval of the Competent Authority is required in respect of every source replacement, sale, transfer, transport, import and export. Further, all licensees are required to send the periodic safety Status reports to AERB as well as reporting of any off normal events. AERB conducts inspection of the facilities to ensure compliance with the safety requirements during operation of the facility. Violation of safety norms by licensee attracts enforcement action which includes suspension, modification or withdrawal of licensee for operation of the facility. Upon completion of the useful life of the source, the licensee decommissions the facility and returns the source to the original supplier. For returning the source, prior

Characterisation of homoflavonoids from three Ophioglossum species using liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry.

Science.gov (United States)

Wan, Chuan-Xing; Luo, Jian-Guang; Gu, Yu-Cheng; Xu, De-Ran; Kong, Ling-Yi

2013-01-01

Homoflavonoids, characterised by one more carbon atom directly added to C6 -C3 -C6 backbone of flavonoids, are rich in the species of genus Ophioglossum. Up to now we have little knowledge about their MS fragmentation patterns. It is therefore necessary to investigate their MS fragmentation pathways so as to distinguish them from other types of flavonoids. To develop a rapid method for identifying homoflavonoids from Ophioglossum based on their characteristic MS fragmentation. Mass spectrometry fragmentation pathways and qualitative analysis of homoflavonoids in three ferns of Ophioglosssum were investigated by using high-performance liquid chromatography coupled with diode-array detection and electrospray ionisation tandem mass spectrometry (HPLC-DAD-ESI/MS(n) ). The analyses of the MS(n) spectra of the homoflavonoids allowed us to classify them into two types according to their fragmentation characteristics. The type I homoflavonoids, with an attached additional carbon atom to the C-3 position of the C-ring, presented the initial competing loss of H2 O and CH2 O from their aglycone ions, compared to the initial removal of H2 O or CO in the case of the type II homoflavonoids, which bear the additional carbon atom at the C-2' site of the B-ring and forming ring D. The above characteristic fragmentations of homoflavonoids were quite different from those of other flavonoids, and were successfully applied to identify homoflavonoids in the crude extracts of three Ophioglossum species. The HPLC-DAD-ESI/MS(n) method obtained in the present study provided a powerful tool for identifying homoflavonoids from ferns in the genus Ophioglossum. Copyright © 2013 John Wiley & Sons, Ltd.

Serum ionised calcium and cardiovascular disease in 45-years old men and women followed for 18 years

DEFF Research Database (Denmark)

Ogard, Christina Gerlach; Petersen, Janne; Jørgensen, Torben

2006-01-01

) and a broader definition of CVD. Persons with ionised serum calcium in the highest quintile were compared with persons in the lower four quintiles. Results: In a univariate analysis persons with ionised serum calcium in the highest quintile had increased risk of IHD (p=0.001) and CVD (p=0.02) compared...

Problems associated with the effects of low doses of ionising radiations

International Nuclear Information System (INIS)

Anon.

1996-01-01

This book is the English version of the report number 34 of the Academie des Sciences, published in October 1995, and entitled 'Problemes lies aux effets des faibles doses des radiations ionisantes'. This report had been endorsed by CODER (Comite des Etudes et Rapports) on February 7, 1995. In dealing with problems associated with ionising radiation, a wide range of important aspects must be taken into account and many different international bodies are concerned with them. It was therefore though useful to make the report available in English. Several additions have been made to the original edition: it has been complemented with three appendices on the cellular, molecular and genetic effects of exposure to low doses of ionising radiations ; it was though useful to give, in addition to the references of the chapters and appendices, a summary of the main relevant work published by French research teams over the past few years; an addendum quotes some of the important contributions made over the past year; a symposium devoted to the effects of low doses of ionising radiations, and to repair enzyme systems will be organized by the Academy at the end of 1997. This will provide the opportunity to re-explore the situation in the light of the data accumulated at that time. This field is evolving rapidly and a periodic evaluation of the new data is mandatory. (authors)

The possibility of lasing in Ne+Ar ionic molecules pumped by a hard ioniser

International Nuclear Information System (INIS)

Boichenko, Aleksandr M; Yakovlenko, Sergei I

2000-01-01

The kinetic model of relaxation in the Ne-Ar-Kr mixture pumped by a hard ioniser is constructed in connection with the analysis of the possibility of lasing at the Ne + Ar→NeAr + transition of the inert-gas ionic exciplexes. The calculations based on the typical rates of plasmachemical reactions demonstrate that the lasing is possible but difficult to realise: One needs high pressures (greater than 16 bar) and high pumping densities (∼ 1 MW cm -3 ). In the most favourable cases, the laser efficiency lies between 0.05 and 0.25%. (active media)

Using ionising radiation against terrorism and contrabandism - dosimetric problems

International Nuclear Information System (INIS)

Ankerhold, U.; Hupe, O.; Buchholz, G.

2006-01-01

As will be explained in more detail in a talk at this conference, the personnel X-ray scanners can be divided into two groups, one using the transmitted X rays for image creation, the other one using the Compton back scatters X-rays. In the case of a backscatter scanner, a narrow, pencil -like X-ray beam is produced by a rotating chopper-wheel. The person/object is scanned in a raster scan pattern. The backscattered X-rays of all points are measured and recorded. The transmission X-ray scanner can use both fan-like and pencil like X-ray beams. The transmission detectors are installed behind the object and detect the absorption of the scanned person. Due to the very low dose values of the X-ray scanner systems in combination with a high dose rate in the direct beam for a short irradiation time, special dosemeters have to be used. In the literature and in manufacturers' specifications, the dose values given for some systems are in the range from 0.05 μSv to 5 μSv per scan with a typical irradiation time of a few milliseconds. Due to this pulse-like character of the radiation fields, the dose rate is several sieverts per hour. For the measurements of the investigated scanner, dosemeters were therefore needed having the capability to measure low doses at high dose rates and to measure in pulsed radiation fields. For the optimization of the measurements, the use of measuring devices with a direct indication is necessary. Ionisation chambers are the most suitable measuring instruments to fulfill these requirements. The difficulty for the measurements with an ionisation chamber is that the leakage charge integrated over time can reach values at the level of the expected radiation-produced charge. Additionally unpredictable variations of the leakage charge can be in the same order of magnitude as the expected signal. This challenge led to the development of a special electronics which allow the execution of time-resolved measurements. With this time resolution, it is

Assembly, destruction and manipulation of atomic, molecular and complex systems

International Nuclear Information System (INIS)

Le Padellec, Arnaud Pierre Frederic

2003-04-01

In this report for Accreditation to Supervise Researches (HDR), the author first indicates his professional curriculum (diplomas, teaching activities, responsibilities in the field of education and research, publications), and then proposes a presentation of his scientific works and researches. He notably proposes an overview of the different experimental techniques he implemented: CRYRING storage ring, confluent beams, flow post-discharge with mass spectrometry and Langmuir probe, crossed beams, and so on. He reports works dealing with the manipulation and destruction of atomic, molecular and complex systems: detachment of atomic anions by electronic impact, detachment and dissociation of small carbon aggregates by electronic impact, dissociative recombination, dissociative ionisation and excitation, creation of pairs of ions, manipulation of sodium fluoride aggregates. He finally presents research projects regarding the assembly of molecular and complex systems

High precision spectroscopy of pionic and antiprotonic atoms; Spectroscopie de precision des atomes pioniques et antiprotoniques

Energy Technology Data Exchange (ETDEWEB)

El-Khoury, P

1998-04-15

The study of exotic atoms, in which an orbiting electron of a normal atom is replaced by a negatively charged particle ({pi}{sup -}, {mu}{sup -}, p, {kappa}{sup -}, {sigma}{sup -},...) may provide information on the orbiting particle and the atomic nucleus, as well as on their interaction. In this work, we were interested in pionic atoms ({pi}{sup -14} N) on the one hand in order to determine the pion mass with high accuracy (4 ppm), and on the other hand in antiprotonic atoms (pp-bar) in order to study the strong nucleon-antinucleon interaction at threshold. In this respect, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high stop density for particles in gas targets at low pressure. Using curved crystals, an extended X-ray source could be imaged onto the detector. Charge-Coupled Devices were used as position sensitive detectors in order to measure the Bragg angle of the transition to a high precision. The use of gas targets resolved the ambiguity owing to the number of K electrons for the value of the pion mass, and, for the first time, strong interaction shift and broadening of the 2p level in antiprotonic hydrogen were measured directly. (author)

Energy dependence of the ionization of highly excited atoms by collisions with excited atoms

International Nuclear Information System (INIS)

Shirai, T.; Nakai, Y.; Nakamura, H.

1979-01-01

Approximate analytical expressions are derived for the ionization cross sections in the high- and low-collision-energy limits using the improved impulse approximation based on the assumption that the electron-atom inelastic-scattering amplitude is a function only of the momentum transfer. Both cases of simultaneous excitation and de-excitation of one of the atoms are discussed. The formulas are applied to the collisions between two excited hydrogen atoms and are found very useful for estimating the cross sections in the wide range of collisions energies

Influence of easily ionised elements on the delayed responses of the emission intensities of an analyte in a power modulated U-shaped argon stabilised DC arc plasma with an aerosol supply

Directory of Open Access Journals (Sweden)

MIROSLAV KUZMANOVIC

2005-09-01

Full Text Available The current of a U-shaped argon stabilised DC arc was square modulated with a 40 Hz repetition frequency between 6 and 3 A. The delayed line intensity responses to the modulation of the arc current were investigated using calcium as a representative analyte. The intensities of both the atomic and ionic lines were monitored at different distances from the arc axis in the presence of various concentrations of the easily ionised element. Temporal evolutions were monitored on a millisecond time scale. It was found that the responses of the line intesity to the arc current change strongly depended on the observed radial position, especially in the vicinity of the arc axis. The obtained results showed a significant influence of even small amounts of the easily ionised element on the excitation and transport of the analyte and indicated a way of possibly improving the analytical capabilities of the excitation source.

Two centre problems in relativistic atomic physics

Energy Technology Data Exchange (ETDEWEB)

McConnell, Sean R.

2013-01-09

The work contained within this thesis is concerned with the explanation and usage of a set of theoretical procedures for the study of static and dynamic two-centre problems in the relativistic framework of Dirac's equation. Two distinctly different theories for handling time-dependent atomic interactions are reviewed, namely semi-classical perturbation theory and a non-perturbative numerical technique based on the coupled channel equation to directly solve the time-dependent, two-centre Dirac equation. The non-perturbative numerical technique has been developed independently and the calculations performed with it are entirely new. Calculations for ionisation cross sections and state occupancies are conducted for both these methods. The non-perturbative technique for relativistic two-centre problems is extensively explained and, given its novelty, a probity test is conducted between this technique and that of the well established perturbation theory in calculating K-and L-shell ionisation cross sections for the alpha decay of initially Hydrogen-like Polonium. To that end, an in depth outline of the perturbative technique is also made for both collision and decay processes. As well as the comparison test mentioned, this technique is also applied to the analysis of cross sections of the promotion of a single electron into the positive continuum from either a K- or L-shell due to the alpha decay of heavy, neutral nuclei (Gadolinium, Polonium and Thorium). Dirac-Coulomb eigenfunctions centred on the parent nucleus of the decay pair are taken as the basis for use in the cross section calculations utilising first order, semi-classical pertubation theory. The excellent congruence between both techniques justifies the usage of the non-perturbative algorithms in the subsequent analysis of collisions between very heavy, highly charged ions. As such, a set of calculations are performed examining the bound and continuum state occupancy of the electronic levels during a

Long term effects of low doses of ionising radiation: facts and fallacies

International Nuclear Information System (INIS)

Iyer, G.K.

1993-01-01

Health effects of low doses of ionising radiation have been a public concern. The public perception of these low effects is that it causes cancer and genetic effects. Enormous amount of work regarding this cancer has been done all over the world, on occupational workers exposed to low doses of ionising radiation. These studies do not show any adverse effect on them. Epidemiological studies done on members of public staying near nuclear facilities also have shown that there is no health risk involved in staying near these facilities. Genetic effects have also shown negative results. These two aspects of health effects of low dose of radiation are discussed in detail. (author). 5 refs., 1 tab

Performance evaluation of synthetic diamond to realize ionisation chamber for radiotherapy application

International Nuclear Information System (INIS)

Guerrero Waryn, M.J.

2005-09-01

This work focuses on the optimisation of synthetic CVD diamond quality to realize ionisation chambers for radiotherapy. Diamonds samples have been synthesized and characterized using thermally stimulated measurement. These measurements showed the presence of trapping levels due to crystalline defects or impurities in material. The study of the response of these samples under irradiation has showed a correlation between the charged state of traps (priming and overshoot phenomena) and the response of the detector (stabilization of the signal). To remove the overshoot phenomenon which prevents from reproducible measurements, we used a specific operating set up controlling the device temperature. This technique enables to neutralize these instable phenomena and to use CVD diamond for ionisation chamber fabrication. (author)

Spectroscopic and thermal properties of uranium relevant to atomic schemes for laser isotope separation

International Nuclear Information System (INIS)

Ahmad, S.A.; Pandey, P.L.

1980-01-01

Spectroscopic data on uranium atom and thermal properties of uranium relevant to atomic schemes for laser isotope separation have been presented in this report. All the relevant spectroscopic data reported in literature so far, as well as some other parameters like photo-absorption cross sections, branching ratios, effects of magnetic and electric fields, evaluated using the existing data, have been presented here. Among the thermal properties, parameters like vapour pressure and number densities for U/Liquid U, U/URe 2 and U/UP systems, partition function, percentage population distribution in energy levels, thermal ionisation and velocities of uranium atom have been presented at different temperatures. Different possible collision processes are mentioned and cross-sections of U-U + charge-exchange and U + + e radiative recombination processes have been also evaluated. (author)

Doubling potential of fibroblasts from different species after ionising radiation

International Nuclear Information System (INIS)

Macieira-Coelho, A.; Diatloff, C.; Malaise, E.

1976-01-01

It is stated that whereas chicken fibroblasts invariably die after a certain number of doublings in vitro, and this fact is never altered by chemical or physical agents, mouse fibroblasts invariably acquire spontaneously an infinite growth potential. In the human species fibroblasts never acquire spontaneously the capacity to divide for ever, although they can become permanent cell lines after treatment with certain viruses. This behaviour of fibroblasts in vitro has been attributed to different nutritional requirements. Experiments are described with human and mouse fibroblasts in which it was found that the response to ionising radiation matches the relative tendencies of the fibroblasts to yield permanent cell lines. Irradiation was commenced during the phase of active proliferation. Human fibroblast cultures irradiated with 100 R stopped dividing earlier than the controls, whereas cultures irradiated with 200, 300 and 500 R had the same lifespan as the control cultures. Cultures irradiated with 400 R showed the longest survival. With mouse fibroblasts the growth curves of the irradiated cells were of the same type as in the controls, but recovery occurred earlier. The results indicated that ionising radiation accelerates a natural phenomenon; in cells with a limited growth potential (chicken) it shortens the lifespan, whereas in cells that can acquire an unlimited growth potential (mouse) it accelerates acquisition of this potential; human fibroblasts showed an intermediate response, since ionising radiation neither established the cultures as with mouse cells nor reduced the number of cells produced as with chicken fibroblasts. Possible explanations for the different behaviour of the species are offered. (U.K.)

Non-targeted effects of ionising radiation—Implications for low dose risk

DEFF Research Database (Denmark)

Kadhim, Munira; Salomaa, Sisko; Wright, Eric

2013-01-01

and adaptive responses are powered by fundamental, but not clearly understood systems that maintain tissue homeostasis. Despite excellent research in this field by various groups, there are still gaps in our understanding of the likely mechanisms associated with non-DNA targeted effects, particularly......Non-DNA targeted effects of ionising radiation, which include genomic instability, and a variety of bystander effects including abscopal effects and bystander mediated adaptive response, have raised concerns about the magnitude of low-dose radiation risk. Genomic instability, bystander effects....... Furthermore, it is still not known what the initial target and early interactions in cells are that give rise to non-targeted responses in neighbouring or descendant cells. This paper provides a commentary on the current state of the field as a result of the non-targeted effects of ionising radiation (NOTE...

High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM.

Science.gov (United States)

Neděla, Vilém; Tihlaříková, Eva; Runštuk, Jiří; Hudec, Jiří

2018-01-01

A new Combined System for high-efficiency detection of Secondary and Backscattered Electrons (CSSBE) in the ESEM consists of three detectors: an ionisation SE detector, an improved scintillation BSE detector, and a new Ionisation Secondary Electron Detector with an electrostatic Separator (ISEDS). The ISEDS optimizes conditions for electron-gas ionisation phenomena in the ESEM to achieve a strongly amplified signal from the secondary electrons with a minimal contribution from backscattered and beam electrons. For this purpose, it is originally equipped with an electrostatic separator, which focuses signal electrons towards a detection electrode and controls the concentration of positive ions above the sample. The working principle of the ISEDS is explained by simulations of signal electron trajectories in gas using the EOD program with our Monte Carlo module. The ability to detect the signal electrons in a selected range of energies is described with Geant4 Monte Carlo simulations of electron-solid interactions and proven by experimental results. High-efficiency detection of the ISEDS is demonstrated by imaging a low atomic number sample under a reduced beam energy of 5 keV, very low beam currents of up to 0.2 pA, and gas pressure of hundreds of Pa. Copyright © 2017 Elsevier B.V. All rights reserved.

The Coulomb deflection effect on the L3-subshell alignment in low-velocity proton impact ionisation

International Nuclear Information System (INIS)

Palinkas, J.; Schlenk, B.; Valek, A.

1981-01-01

The alignment parameter of the L 3 subshell of gold has been determined by measuring the angular distribution of the Lsub(l)/Lsub(γ) intensity ratio following proton impact ionisation in the 0.25-0.60 MeV energy range. The experimental results make it clear that the minimum of the alignment parameter at low energies found earlier for He + impact also exists in the case of proton impact ionisation. (author)

The potential use of diamond coated tungsten tips as a field ionisation source

Energy Technology Data Exchange (ETDEWEB)

Brown, A.; Prawer, S.; Legge, G.J.F.; Kostidis, L.I. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1996-12-31

Tungsten tips are convenient for use in a high brightness gaseous phase field ionisation source. However, the lifetime of these tips is not adequate for practical use. The authors are investigating whether coating tungsten tips with diamond using Chemical Vapor Deposition (CVD) will improve the practicality of using these tips by an improvement in longevity of the source and/or an improvement in brightness due to the effects of the property of negative electron affinity which has been observed on CVD diamond. 1 ref.

The potential use of diamond coated tungsten tips as a field ionisation source

Energy Technology Data Exchange (ETDEWEB)

Brown, A; Prawer, S; Legge, G J.F.; Kostidis, L I [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-12-31

Tungsten tips are convenient for use in a high brightness gaseous phase field ionisation source. However, the lifetime of these tips is not adequate for practical use. The authors are investigating whether coating tungsten tips with diamond using Chemical Vapor Deposition (CVD) will improve the practicality of using these tips by an improvement in longevity of the source and/or an improvement in brightness due to the effects of the property of negative electron affinity which has been observed on CVD diamond. 1 ref.

ADAS: Atomic data, modelling and analysis for fusion

International Nuclear Information System (INIS)

Summers, H. P.; O'Mullane, M. G.; Whiteford, A. D.; Badnell, N. R.; Loch, S. D.

2007-01-01

The Atomic Data and Analysis Structure, ADAS, comprises extensive fundamental and derived atomic data collections, interactive codes for the manipulation and generation of collisional-radiative data and models, off-line codes for large scale fundamental atomic data production and codes for diagnostic analysis in the fusion and astrophysical environments. ADAS data are organized according to precise specifications, tuned to application and are assigned to numbered ADAS data formats. Some of these formats contain very large quantities of data and some have achieved wide-scale adoption in the fusion community.The paper focuses on recent extensions of ADAS designed to orient ADAS to the needs of ITER. The issue of heavy atomic species, expected to be present as ITER wall and divertor materials, dopants or control species, will be addressed with a view to the economized handling of the emission and ionisation state data needed for diagnostic spectral analysis. Charge exchange and beam emission spectroscopic capabilities and developments in ADAS will be reviewed from an ITER perspective and in the context of a shared analysis between fusion laboratories. Finally an overview and summary of current large scale fundamental data production in the framework of the ADAS project will be given and its intended availability in both fusion and astrophysics noted

The ionisation equation in a relativistic gas

International Nuclear Information System (INIS)

Kichenassamy, S.; Krikorian, R.A.

1983-01-01

By deriving the relativistic form of the ionisation equation for a perfect gas it is shown that the usual Saha equation is valid to 3% for temperatures below one hundred million Kelvin. Beyond 10 9 K, the regular Saha equation is seriously incorrect and a relativistic distribution function for electrons must be taken into account. Approximate forms are derived when only the electrons are relativistic (appropriate up to 10 12 K) and also for the ultrarelativistic case (temperatures greater than 10 15 K). (author)

Microdosimetric constraints on specific adaptation mechanisms to reduce DNA damage caused by ionising radiation

International Nuclear Information System (INIS)

Burkart, W.; Heusser, P.; Vijayalaxmi

1990-01-01

The protective effect of pre-exposure of lymphocytes to ionising radiation indicates the presence of 'adaptive repair' in mammalian cells. Microdosimetric considerations, however, raise some doubts on the advantage of such a cellular mechanism for specifically reducing the radiation damage caused by environmental exposures. Contrary to most chemicals which endanger the integrity of the mammalian genome, the local dose and dose rate from ionising radiation at the cellular level remain quite high, even at lowest exposures. A single electron or alpha particle passing through a cell nucleus already yields nuclear doses of up to about 3 mGy and 400 mGy, respectively. Macroscopic doses below these nuclear doses from a single event will only reduce the fraction of cell nuclei encountering the passage of a particle but not the dose or dose rate in the affected volume. At environmental doses in the range of 1 to 5 mGy per annum, the time between two consecutive hits in a specific cell nucleus is in the range of months to years. Very low concentrations of bleomycin, a drug with high affinity to DNA, also triggers an adaptive response. This points to a more general stress response mechanism which may benefit the cell even at environmental levels of radioactivity, e.g. by protecting the integrity of DNA from attacks by chemicals, by endogenous radicals, by acids from anoxia, etc. (author)

Study and optimization of the ionisation channel in the Edelweiss dark matter direct detection experiment; Etude et optimisation de la voie ionisation dans l'experience Edelweiss de detection directe de la matiere noire

Energy Technology Data Exchange (ETDEWEB)

Censier, B

2006-02-15

The EDELWEISS experiment is aiming at the detection of Weakly Interactive Massive Particles (WIMPs), today's most favoured candidates for solving the dark matter issue. Background ionising particles are identified thanks to the simultaneous measurement of heat and ionisation in the detectors. The main limitation to this method is coming from the ionisation measurement, charge collection being less efficient in some part of the detectors known as 'dead' areas. The specificity of the measurement is due to the use of very low temperatures and low collection fields. This thesis is dedicated to the study of carrier trapping. It involves time-resolved charge measurements as well as a simulation code adapted to the specific physical conditions. We first present results concerning charge trapping at the free surfaces of the detectors. Our method allows to build a surface-charge in a controlled manner by irradiation with a strong radioactive source. This charge is then characterised with a weaker source which acts as a probe. In a second part of the work, bulk-trapping characteristics are deduced from charge collection efficiency measurements, and by an original method based on event localisation in the detector. The results show that a large proportion of the doping impurities are ionised, as indicated independently by the study of degradation by space-charge build-up. In this last part, near-electrodes areas are found to contain large densities of charged trapping centres, in connection with dead-layer effects. (author)

Ionising radiation safety training in the Australian defence organisation (ADO)

International Nuclear Information System (INIS)

Jenks, G.J.; O'Donovan, E.J.B.; Wood, W.B.

1996-01-01

Full text: Training personnel in ionising radiation safety within the Australian Defence Organisation (ADO) requires addressing some unique features of an organisation employing both military and civilian personnel. Activities may include those of a civil nature (such as industrial and medical radiography), specific military requirements (for training and emergency response) and scientific research and development. Some personnel may be assigned to full-time duties associated with radiation, while others may be designated as radiation protection officers in remote units with few duties to perform in this role. A further complication is that most military personnel are subjected to postings at regular intervals. The ADO's Directorate of Defence Occupational Health and Safety has established an Ionising Radiation Safety Subcommittee to monitor not only the adequacy of the internal Ionising Radiation Safety Manual but also the training requirements. A training course, responding to these requirements, has been developed to emphasise: basic radiation theory and protection; operation of radiation monitors available in the ADO; an understanding of the Safety Manual; day-to-day radiation safety in units and establishments; and appropriate responses to radiation accidents and emergencies. In addition, students are briefed on a limited number of peripheral topics and participate in some site visits. Currently, two Courses are held annually, each with about twenty students. Most of the material is presented by ADO personnel with external contractor support. The three Courses held to date have proved sufficiently successful, both for the students and the ADO generally, to seek national accreditation through the Australian National Training Authority and, as a first step, competency standards have been identified

Deployment of the FIGAERO Iodide Time of flight (ToF)-Chemical ionisation mass spectrometer (CIMS) using X-ray ionisation in Manaus

Science.gov (United States)

Bannan, T.; Bacak, A.; Priestley, M.; Adelstein, E.; Worrall, S.; Artaxo, P.; Carbone, S.; Topping, D. O.; Allan, J. D.; Coe, H.; Percival, C.

2017-12-01

Here the deployment of the The Filter Inlet for Gases and AEROsols (FIGAERO) coupled with the Aerodyne High Resolution (HR)-Time of flight (ToF)-Chemical ionisation mass spectrometer (CIMS) in Manaus is presented. This project utilised the Tofwerk X-ray ionisation source in the tropical rainforest in close proximity to Manaus, Brazil, at the ZF2 measurement site. The FIGAERO is a filter based technique that provides simultaneous molecular information of both the gas and particle phase. When analysing particles that have been collected the evolution of the MS signals from different compounds change independently as a function of temperature; creating a thermogram that is m/z specific. The temperature for which the desorbed signal shows a maximum for each compound has been used previously to extract vapour pressure information in laboratory characterisatio. Krieger et al. (2017) defined the homologous series of polyethylene glycols as a series of compounds that showed a very good agreement over a wide range of atmospherically relevant vapour pressures between different experimental setups. PEG samples therefore provide an ideal bench mark for characterising individual FIGAERO inlets to give vapour pressure information essential for partitioning characterisation. The PEG calibration curve has been used to validate vapour pressure measurements in a well-defined single component bases and in simple chamber experiments, results of which are presented. With a high reactivity and large ubiquitous global source, isoprene has a profound effect upon atmospheric chemistry and composition. Despite this there are still significant gaps in the understanding of the processes that lead to isoprene derived secondary organic aerosol (SOA). This project aims to provide insights into the role of isoprene in the mechanisms of production of SOA and its importance in the particulate mass budgets in the tropics and the fundamental chemical processes. The volatility and composition of

Control and calculation of the titanium sublimation pumping speed and re-ionisation in the MAST neutral beam injectors

International Nuclear Information System (INIS)

McAdams, R.

2015-01-01

Highlights: • The titanium sublimation pumps for the MAST neutral beam injectors are described. • Evaporation regimes are established to give constant pumping speed for the titanium sublimation pumps. • The MCNP code is used to calculate the pumping speeds and gas profiles in the neutral beam injectors. • The gas profiles are then used to calculate the level of re-ionisation in the beamline. - Abstract: A high pumping speed is required in neutral beam injectors to minimise re-ionisation of the neutral beams. The neutral beam injectors on MAST use titanium sublimation pumps. These pumps do not have a constant pumping speed; their pumping speed depends on the gettering surface history and on both the integrated and applied gas load. In this paper we describe a method of maintaining a constant pumping speed, through different evaporation schemes, specifically suitable for operations of the MAST neutral beam injector beamlines for both short and relatively long beam pulses by measurement of the pressure in the beamline. In addition the MCNP code is then used to calculate the pumping speed and gas profile in the beamline by adjusting the input pumping speed to match the measured pressure. This allows the resulting gas profile to be used for calculation of the re-ionisation levels and an example is given

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs

Energy Technology Data Exchange (ETDEWEB)

Fessler, P. [11 rue Rabelais, 92170 Vanves (France); Coffin, J. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Eberle, H. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Raad Iseli, C. de [Smart Silicon Systems SA, Ch. de la Graviere 6, CH-1007 Lausanne (Switzerland); Hilt, B. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Huss, D. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Krummenacher, F. [Smart Silicon Systems SA, Ch. de la Graviere 6, CH-1007 Lausanne (Switzerland); Lutz, J.R. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Prevot, G. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Renouprez, A. [Institut de Recherche sur la Catalyse, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Sigward, M.H. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France); Schwaller, B. [Universite de Haute-Alsace, GRPHE, 61, rue Albert Camus, 68093 Mulhouse (France); Voltolini, C. [Institut de Recherches Subatomiques, B.P. 28, 67037 Strasbourg (France)

1999-01-21

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190 e rms (input non connected, peaking time 500 ns), the highest gain is 255 mV/fC, the peaking time is adjustable between 200 ns and 2 {mu}s and the power consumption is 10 mW per channel. The agreement between experimental data and theoretical simulation results is excellent.

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs

International Nuclear Information System (INIS)

Fessler, P.; Coffin, J.; Eberle, H.; Raad Iseli, C. de; Hilt, B.; Huss, D.; Krummenacher, F.; Lutz, J.R.; Prevot, G.; Renouprez, A.; Sigward, M.H.; Schwaller, B.; Voltolini, C.

1999-01-01

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus, the use of on-line corrections of the inevitable dispersion of characteristics between the large number of electronic channels of the detection system, shall be precluded. Without claiming to achieve ultimate noise levels, the work described is focused on how to prevent good individual acquisition channel noise performance from being totally destroyed by the dispersion between channels without introducing dead times. With this goal, we developed an automatic charge amplifier output voltage offset compensation system which operates regardless of the cause of the offset (detector or electronic). The main performances of the system are the following: the input equivalent noise charge is 190 e rms (input non connected, peaking time 500 ns), the highest gain is 255 mV/fC, the peaking time is adjustable between 200 ns and 2 μs and the power consumption is 10 mW per channel. The agreement between experimental data and theoretical simulation results is excellent

The influence of atomic alignment on absorption and emission spectroscopy

Science.gov (United States)

Zhang, Heshou; Yan, Huirong; Richter, Philipp

2018-06-01

Spectroscopic observations play essential roles in astrophysics. They are crucial for determining physical parameters in the universe, providing information about the chemistry of various astronomical environments. The proper execution of the spectroscopic analysis requires accounting for all the physical effects that are compatible to the signal-to-noise ratio. We find in this paper the influence on spectroscopy from the atomic/ground state alignment owing to anisotropic radiation and modulated by interstellar magnetic field, has significant impact on the study of interstellar gas. In different observational scenarios, we comprehensively demonstrate how atomic alignment influences the spectral analysis and provide the expressions for correcting the effect. The variations are even more pronounced for multiplets and line ratios. We show the variation of the deduced physical parameters caused by the atomic alignment effect, including alpha-to-iron ratio ([X/Fe]) and ionisation fraction. Synthetic observations are performed to illustrate the visibility of such effect with current facilities. A study of PDRs in ρ Ophiuchi cloud is presented to demonstrate how to account for atomic alignment in practice. Our work has shown that due to its potential impact, atomic alignment has to be included in an accurate spectroscopic analysis of the interstellar gas with current observational capability.

Study and optimization of the ionisation channel in the Edelweiss dark matter direct detection experiment

International Nuclear Information System (INIS)

Censier, B.

2006-02-01

The EDELWEISS experiment is aiming at the detection of Weakly Interactive Massive Particles (WIMPs), today's most favoured candidates for solving the dark matter issue. Background ionising particles are identified thanks to the simultaneous measurement of heat and ionisation in the detectors. The main limitation to this method is coming from the ionisation measurement, charge collection being less efficient in some part of the detectors known as 'dead' areas. The specificity of the measurement is due to the use of very low temperatures and low collection fields. This thesis is dedicated to the study of carrier trapping. It involves time-resolved charge measurements as well as a simulation code adapted to the specific physical conditions. We first present results concerning charge trapping at the free surfaces of the detectors. Our method allows to build a surface-charge in a controlled manner by irradiation with a strong radioactive source. This charge is then characterised with a weaker source which acts as a probe. In a second part of the work, bulk-trapping characteristics are deduced from charge collection efficiency measurements, and by an original method based on event localisation in the detector. The results show that a large proportion of the doping impurities are ionised, as indicated independently by the study of degradation by space-charge build-up. In this last part, near-electrodes areas are found to contain large densities of charged trapping centres, in connection with dead-layer effects. (author)

Ionising radiation: a guide to the Regulations

International Nuclear Information System (INIS)

Hughes, Donald.

1986-01-01

The author explains the basic requirements on health and safety personnel in relation to the Ionising Radiations Regulations 1985. The outline paper is presented under the following headings: Dose assessment, Interpretation and general regulations 1-5, Dose limitation regulations 6 and 7, Regulation of work - regulations 8-12, Dosimetry and medical surveillance - regulations 13-17, summary of records to be kept, entry to controlled areas, Control of radioactive substances -regulations 18-23, Monitoring of radiation regulation 24, Assessments and notifications - regulations 25-31, Safety of articles and equipment - regulations 32-34, Other guidance. (U.K.)

Rapid evaporative ionisation mass spectrometry and chemometrics for high-throughput screening of growth promoters in meat producing animals.

Science.gov (United States)

Guitton, Yann; Dervilly-Pinel, Gaud; Jandova, Renata; Stead, Sara; Takats, Zoltan; Le Bizec, Bruno

2018-01-17

In a proof of concept perspective, Rapid Evaporative Ionisation Mass Spectrometry (REIMS) was explored for the direct analysis of meat samples from β-agonist treated livestock. In this context, the combination of REIMS with untargeted metabolomics was investigated to identify carcasses from treated animals on the basis of a modification of indirect metabolites profile. The REIMS analysis generated specific lipid profiles which enabled the differentiation of meat samples collected from pigs treated with ractopamine via their feeding regime. Furthermore, the strategy was found successful when tested on different muscle types (loin, shoulder and thigh), which further expands its applicability. Classification performances were greater than 95% accurate which fully answers requirements of a screening strategy. This research indicates that REIMS implemented in an untargeted-metabolomics workflow can be considered as a high-throughput and accurate strategy for real-time meat classification in relation to ractopamine (and wider β-agonists) treatment in pig production. This approach may subsequently be implemented as a rapid screening test, at the slaughterhouse or at border inspection points, to detect such practice.

Atom and molecule projectile and fast aggregate excitation, ionization and dissociation in thin targets in the out-of-charge equilibrium field

International Nuclear Information System (INIS)

Clouvas, A.

1985-12-01

The aim of this experimental study is to confirm the possible existence of bound states for light atomic and molecular projectiles inside solid targets, in the MeV energy range. For this purpose we have used, various experimental methods such as charge state distribution measurements, energy loss measurements, beam foil spectroscopy and electron spectroscopy. It was confirmed that bound states of light atomic and molecular projectiles can exist in a solid medium. The various cross sections (charge exchange, excitation, ionisation, dissociation) relative to these bound states have been measured [fr

Voxel anthropomorphic phantoms: review of models used for ionising radiation dosimetry

International Nuclear Information System (INIS)

Lemosquet, A.; Carlan, L. de; Clairand, I.

2003-01-01

Computational anthropomorphic phantoms have been used since the 1970's for dosimetric calculations. Realistic geometries are required for this operation, resulting in the development of ever more accurate phantoms. Voxel phantoms, consisting of a set of small-volume elements, appeared towards the end of the 1980's, and significantly improved on the original mathematical models. Voxel phantoms are models of the human body, obtained using computed tomography (CT) or magnetic resonance images (MRI). These phantoms are an extremely accurate representation of the human anatomy. This article provides a review of the literature available on the development of these phantoms and their applications in ionising radiation dosimetry. The bibliographical study has shown that there is a wide range of phantoms, covering various characteristics of the general population in terms of sex, age or morphology, and that they are used in applications relating to all aspects of ionising radiation. (author)

Atomic physics with highly charged ions

International Nuclear Information System (INIS)

Richard, P.

1991-08-01

This report discusses: One electron outer shell processes in fast ion-atom collisions; role of electron-electron interaction in two-electron processes; multi-electron processes at low energy; multi-electron processes at high energy; inner shell processes; molecular fragmentation studies; theory; and, JRM laboratory operations

Mesonic atom production in high-energy nuclear collisions

International Nuclear Information System (INIS)

Wakai, M.; Bando, H.; Sano, M.

1987-08-01

The production probability of π-mesonic atom in high-energy nuclear collisions is estimated by a coalescence model. The production cross section is calculated for p + Ne and Ne + Ne systems at 2.1 GeV/A and 5.0 GeV/A beam energy. It is shown that nuclear fragments with larger charge numbers have the advantage in the formation of π-mesonic atoms. The cross section is proportional to Z 3 and of the order of magnitude of 1 ∼ 10 μb in all the above cases. The production cross sections of K-mesonic atoms are also estimated. (author)

Selective excitation of atoms or molecules to high-lying states

International Nuclear Information System (INIS)

Ducas, T.W.

1978-01-01

This specification relates to the selective excitation of atoms or molecules to high lying states and a method of separating different isotopes of the same element by selective excitation of the isotopes. (U.K.)

The Ionising Radiations Advisory Committee Open Meeting 10 October 2001

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-12-01

Full text: The Ionising Radiations Advisory Committee (IRAC) held its first open meeting on 10 October 2001 in response to a request from the Health and Safety Commission (HSC) that all its advisory committees should follow the Commission's example and hold such meetings. Some of the other advisory committees have already held open meetings and others are planning to do so shortly. The aim of the meeting was to enable members of the public to meet IRAC members and to find out more about the Committee - how it worked and the type of issues it dealt with. The first two sessions were devoted to short presentations describing IRAC's work and influences, now and in the future, on radiation protection generally. The third session was a discussion forum. The agenda for the meeting and the presentations are posted on the web at: www.hse.gov.uk/foi/iracopen.htm. Each session of presentations was followed by questions of clarification and the third session of the meeting comprised an open forum. Many of the questions raised were not directly relevant to IRAC but, nevertheless, members provided brief responses and referred questions on to others as appropriate. One question had been notified in advance, asking whether members of IRAC agreed that it is now (regrettably) reasonably foreseeable that a loss of containment of radioactive material may occur at a nuclear facility as a result of impact by an aeroplane or by other hostile acts, and that this should be made clear in published guidance on REPPIR. This question was not within IRAC's remit. The Chairman of the Nuclear Safety Advisory Committee offered to take the question to the Committee's next meeting. Issues discussed included: Concerns that exposure to ionising radiation at low levels is more dangerous than is currently reflected in risk estimates. The European Parliament has adopted a resolution calling on the main international bodies, including the International Commission on Radiological

Conversion of electromagnetic waves at the ionisation front

International Nuclear Information System (INIS)

Chegotov, M V

2001-01-01

It is shown that a weak electromagnetic pulse interacting with a copropagating ionisation front is converted in the general case into three electromagnetic pulses with higher and lower frequencies, which propagate in different directions. The coefficients of conversion to these pulses (for intensities) were found as functions of the frequency. The electromagnetic energy is shown to decrease during this conversion because of the losses for the residual electron energy. (interaction of laser radiation with matter. laser plasma)

High-efficiency one-dimensional atom localization via two parallel standing-wave fields

International Nuclear Information System (INIS)

Wang, Zhiping; Wu, Xuqiang; Lu, Liang; Yu, Benli

2014-01-01

We present a new scheme of high-efficiency one-dimensional (1D) atom localization via measurement of upper state population or the probe absorption in a four-level N-type atomic system. By applying two classical standing-wave fields, the localization peak position and number, as well as the conditional position probability, can be easily controlled by the system parameters, and the sub-half-wavelength atom localization is also observed. More importantly, there is 100% detecting probability of the atom in the subwavelength domain when the corresponding conditions are satisfied. The proposed scheme may open up a promising way to achieve high-precision and high-efficiency 1D atom localization. (paper)

Compton spectra of atoms at high x-ray intensity

Science.gov (United States)

Son, Sang-Kil; Geffert, Otfried; Santra, Robin

2017-03-01

Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL-matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

Excited Atoms and Molecules in High Pressure Gas Discharges

International Nuclear Information System (INIS)

Vuskovic, L.; Popovic, S.

2003-01-01

Various types of high-pressure non-thermal discharges are increasingly drawing attention in view of many interesting applications. These, partially ionized media in non-equilibrium state, tend to generate complex effects that are difficult to interpret without a detailed knowledge of elementary processes involved. Electronically excited molecules and atoms may play an important role as intermediate states in a wide range of atomic and molecular processes, many of which are important in high-pressure discharges. They can serve also as reservoirs of energy or as sources of high energy electrons either through the energy pooling or through superelastic collisions. By presenting the analysis of current situation on the processes involving excited atoms and molecules of interest for high-pressure gas discharges, we will attempt to draw attention on the insufficiency of available data. In the same time we will show how to circumvent this situation and still be able to develop accurate models and interpretations of the observed phenomena

Ion pair production and chemi-ionisation in collisions of He*(2sup(1,3)S) with Li

International Nuclear Information System (INIS)

Wang, D.P.; Tang, S.Y.; Neynaber, R.H.

1987-01-01

A merging-beams technique has been used to study collisions of He*(2sup(1,3)S) with Li. The He* represents a composite of 13% He(2 1 S) and 87% He(2 3 S). Absolute and relative cross sections, Q, have been measured in a range of relative kinetic energy, W, from 150 to 1500 eV for the ion pair production (IPP) of He + + Li - , and from 0.01 to 500 eV for chemi-ionisation (CI). Information obtained for CI shows that: the Penning ionisation reaction is directed with most of the Li + scattered in the incident Li direction, the He*-Li system is attractive with a measured well depth of 0.73 eV and the value of Q for total ionisation varies as Wsup(-0.34). Similarities to the He*-He* system are also given. (author)

Nonlinear collisionless electron cyclotron interaction in the pre-ionisation stage

Science.gov (United States)

Farina, D.

2018-06-01

Electron cyclotron (EC) wave-particle interaction is theoretically investigated in the pre-ionisation phase, much before collisions and other mechanisms can play a role. In the very first phase of a plasma discharge with EC-assisted breakdown, the motion of an electron at room temperature in a static magnetic field under the action of a localised microwave beam is nonlinear, and transition to states of larger energy can occur via wave trapping. Within a Hamiltonian adiabatic formalism, the conditions at which the particles gain energy in single beam crossing are derived in a rigorous way, and the energy variation is characterized quantitatively as a function of the wave frequency, harmonic number, polarisation and EC power and beam width. Estimates of interest for applications to tokamak start-up are obtained for the first, second and third cyclotron harmonic. The investigation confirms that electrons can easily gain energies well above the ionisation energy in most conditions at the first two harmonics, while not at the third harmonic, as observed in experiments.

Evaluation of cytogenetic damage in nuclear medicine personnel occupationally exposed to low-level ionising radiation

International Nuclear Information System (INIS)

Garaj-Vrhovac, V.; Kopjar, N.; Poropat, M.

2005-01-01

Despite intensive research over the last few decades, there still remains considerable uncertainty as to the genetic impact of ionising radiation on human populations, particularly at low levels. The aim of this study was to provide data on genetic hazards associated with occupational exposure to low doses of ionising radiation in nuclear medicine departments. The assessment of DNA damage in peripheral blood lymphocytes of medical staff was performed using the chromosome aberration (CA) test. Exposed subjects showed significantly higher frequencies of CA than controls. There were significant inter-individual differences in DNA damage within the exposed population, indicating differences in genome sensitivity. Age and gender were not confounding factors, while smoking enhanced the levels of DNA damage only in control subjects. The present study suggests that chronic exposure to low doses of ionising radiation in nuclear medicine departments causes genotoxic damage. Therefore, to avoid potential genotoxic effects, the exposed medical personnel should minimise radiation exposure wherever possible. Our results also point to the significance of biological indicators providing information about the actual risk to the radiation exposed individuals.(author)

Veterinary applications of ionising radiation HERCA Task Force on Veterinary Applications. Main results of the Questionnaire 'National regulatory requirements with regard to veterinary medical applications of ionising radiation' and conclusions of the TF

International Nuclear Information System (INIS)

Van Bladel, Lodewijk; Berlamont, Jolien; Michalczak, Herbert; Balogh, Lajos; Peremans, Kathelijne

2013-11-01

In the fall of 2012, the subject of radiation protection in veterinary medicine was raised during the meeting of the HERCA Board. Issues with regard to this subject had been brought to the attention of HERCA by the European College of Veterinary Diagnostic Imaging (ECVDI). In October 2012, the Board decided to charge a small Task Force (TF) to further explore the issues in this field. This TF drew up a questionnaire which looked at the general radiation protection regulatory requirements in veterinary medicine applications of ionizing radiation. The results of this study showed large differences in the requirements applicable in the HERCA member countries. The TF also noticed the increasing use of more complex imaging procedures and of different radio-therapeutic modalities, which may imply greater risks of exposure of humans to ionising radiation. These results were presented during the HERCA Board meeting in Berlin, Germany and on which the Board decided to establish a Working Group on veterinary applications of ionising radiations (WG Vet). The main results of the Questionnaire 'National regulatory requirements with regard to veterinary medicine applications of ionising radiation' is attached in Appendix

Double ionisation of helium in fast ion collisions: the role of momentum transfer

International Nuclear Information System (INIS)

Bapat, B.; Moshammer, R.; Schmitt, W.; Kollmus, H.; Ullrich, J.; Doerner, R.; Weber, T.; Khayyat, K.

1999-01-01

Double ionisation of helium in the perturbative regime has been explored in a kinematically complete collision experiment using 100 MeV/u C 6+ ions. Different ionisation mechanisms are identified by inspecting the angular distribution of the electrons as a function of the momentum transfer q to the target by the projectile. For q 1.2 a.u., the faster electron resulting from a binary encounter with the projectile is emitted along the direction of momentum transfer, while the other electron is distributed uniformly. Experimental data are compared with various model calculations based on the Bethe-Born approximation with shake-off. Surprisingly, the effect of the final state interaction is found to depend decisively on the choice of the initial state wave function. (orig.)

Training courses run by the Department of Atomic Energy, India

International Nuclear Information System (INIS)

1981-01-01

The Department of Atomic Energy (DAE), India, conducts a large number of courses covering a variety of fields, mainly concerned with nuclear energy and its applications. These courses are : (1) a comprehensive multidisciplinary course in nuclear sciences and engineering, (2) courses in safety aspects of: (a) the medical uses of radioisotopes, (b) research applications of ionising radiations, (c) the industrial applications of radiation sources, and (d) industrial radiography; (3) industrial radiographer's certification course, (4) course in hospital physics and radiological physics, (5) diploma course in radiation medicine, (6) courses in operation and maintenance of: (a) research reactors and facilities, (b) nuclear power reactors, and (7) course in exploration of atomic minerals. Detailed information on these courses, covering institutions of DAE conducting them, duration, academic requirements for admission to them, method of adimission, detailed syllabus, and general information such as fees, accommodation, stipend if any, etc. is given. (M.G.B.)

Fluorescence in situ hybridisation in chromosome aberration detection in subjects occupationally exposed to ionising radiation

International Nuclear Information System (INIS)

Zeljezic, D.; Garaj-Vrhovac, V.

2005-01-01

For more than two decades, chromosomal aberration analysis has been used to detect structural chromosomal aberrations as sensitive biodosimeters of occupational exposure to ionising radiation. Its use is also recommended by the World Health Organisation. Changes in chromosome structure detected by that method are considered to be early biomarkers of a possible malignant disease. Aberrations detected by the method are unstable and can be found in the lymphocytes of irradiated personnel only within a limited time after exposure. To detect stable chromosomal aberrations, which persist after exposure, multicolour fluorescent in situ hybridisation has to be used. Using DNA probes labelled with different fluorochromes, it dyes each pair of chromosomes with different colour. Due to the dynamic of unstable aberration formation, chromosomal aberration analysis is more suitable in genome damage assessment of recent exposures. On the other hand, fluorescence in situ hybridisation gives the information on chromosome instability caused by long-term occupational exposure to ionising radiation. Considering the high costs of fluorescence in situ hybridisation and the uncertainty of the result, it should be used in biodosimetry only when it is absolutely necessary.(author)

Comparative study of dense plasma state equations obtained from different models of average-atom

International Nuclear Information System (INIS)

Fromy, Patrice

1991-01-01

This research thesis addresses the influence of temperature and density effects on magnitudes such as pressure, energy, ionisation, and on energy levels of a body described according to the approximation of an electrically neutral isolated atomic sphere. Starting from the general formalism of the functional density, with some approximations, the author deduces the Thomas-Fermi, Thomas-Fermi-Dirac, and Thomas-Fermi-Dirac-Weizsaecker models, and an average-atom approximated quantum model. For each of these models, the author presents an explicit method of resolution, as well as the determination of different magnitudes taken into account in this study. For the different studied magnitudes, the author highlights effects due to the influence of temperature and of density, as well as variations due to the different models [fr

Classical-quantal coupling in the capture of muons by hydrogen atoms

International Nuclear Information System (INIS)

Kwong, N.H.; Garcia, J.D.

1989-01-01

We describe a self-consistent semiclassical approach to the problem of muon capture by hydrogen atoms. The dynamics of the heavier muon and proton are treated classically, and the electron quantally, with the potentials for both being self-consistently determined. Our numerical results are compared to classical-trajectory Monte Carlo (CTMC) and adiabatic ionisation (AI) results. Our capture cross sections are larger at low energy but fall more rapidly to zero. Our results provide the corrections to the dynamics beyond the adiabatic picture, which were missing in other approaches; interesting questions concerning the quantal nature of the events are discussed. (author)

High performance platinum single atom electrocatalyst for oxygen reduction reaction

Science.gov (United States)

Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

2017-07-01

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Ionization of small molecules by state-selected neon (3P0, 3P2) metastable atoms in the 0.06

NARCIS (Netherlands)

Berg, van den F.T.M.; Schonenberg, J.H.M.; Beijerinck, H.C.W.

1987-01-01

The velocity dependence and absolute values of the total ionisation cross section for the molecules H2, N2, O2, NO, CO, N2O, CO2, and CH4 by metastable Ne* (3P0) and Ne* (3P2) atoms at collision energies ranging from 0.06 to 6.0 eV have been measured in a crossed beam experiment. State selection of

Rapid detection of nicotine from breath using desorption ionisation on porous silicon.

Science.gov (United States)

Guinan, T M; Abdelmaksoud, H; Voelcker, N H

2017-05-04

Desorption ionisation on porous silicon (DIOS) was used for the detection of nicotine from exhaled breath. This result represents proof-of-principle of the ability of DIOS to detect small molecular analytes in breath including biomarkers and illicit drugs.

Ionised media and fractures: application to cartilaginous tissues and oil industry

NARCIS (Netherlands)

Huyghe, J.M.R.J.; Kraaijeveld, F.; Remmers, J.J.C.; Borst, de R.; Denier, J; Finn, M.D.; Mattner, T

2008-01-01

ionized media are ubiquitous in nature. Our body holds onto water through ionised macromolecules that bind water up to a 1000 times their own mass. Clays and shales do a similar trick in the geoworld. Localization of deformation and fractures are very common. Bore hole instability through fracture

A slow atomic diffusion process in high-entropy glass-forming metallic melts

Science.gov (United States)

Chen, Changjiu; Wong, Kaikin; Krishnan, Rithin P.; Embs, Jan P.; Chathoth, Suresh M.

2018-04-01

Quasi-elastic neutron scattering has been used to study atomic relaxation processes in high-entropy glass-forming metallic melts with different glass-forming ability (GFA). The momentum transfer dependence of mean relaxation time shows a highly collective atomic transport process in the alloy melts with the highest and lowest GFA. However, a jump diffusion process is the long-range atomic transport process in the intermediate GFA alloy melt. Nevertheless, atomic mobility close to the melting temperature of these alloy melts is quite similar, and the temperature dependence of the diffusion coefficient exhibits a non-Arrhenius behavior. The atomic mobility in these high-entropy melts is much slower than that of the best glass-forming melts at their respective melting temperatures.

High data-rate atom interferometers through high recapture efficiency

Science.gov (United States)

Biedermann, Grant; Rakholia, Akash Vrijal; McGuinness, Hayden

2015-01-27

An inertial sensing system includes a magneto-optical trap (MOT) that traps atoms within a specified trapping region. The system also includes a cooling laser that cools the trapped atoms so that the atoms remain within the specified region for a specified amount of time. The system further includes a light-pulse atom interferometer (LPAI) that performs an interferometric interrogation of the atoms to determine phase changes in the atoms. The system includes a controller that controls the timing of MOT and cooling laser operations, and controls the timing of interferometric operations to substantially recapture the atoms in the specified trapping region. The system includes a processor that determines the amount inertial movement of the inertial sensing system based on the determined phase changes in the atoms. Also, a method of inertial sensing using this inertial sensing system includes recapture of atoms within the MOT following interferometric interrogation by the LPAI.

International responsability of state by the deleterius effects of ionising radiation

International Nuclear Information System (INIS)

Faria, N.M. de.

1988-01-01

International Responsability of State, considering the deleterius effects of ionising radiation on the human being, property, territory and environment which are under other jurisdiction, is focused. Conventional rules, costumary rules, the evolution of ''opinion juris'' as well as the decisions of tribunals related to the subject are analysed. (author) [pt

Injuries to embryo and foetus from ionising radiation

International Nuclear Information System (INIS)

Devik, F.

1980-01-01

A brief review is given of experimental and clinical evidence for tetatological effects of ionising radiation, against the background of general teratology. International and national recommendations and regulations for the protection of the conceptus are quoted. As to interruption of a pregnancy following an unintended exposure, it is pointed out that much of the present evidence points to a dose in the order of 0.1Gy (10 rads) as a dose which may be considered as a practical threshold for the induction of congenital defects. (Auth.)

High-precision two-dimensional atom localization via quantum interference in a tripod-type system

International Nuclear Information System (INIS)

Wang, Zhiping; Yu, Benli

2014-01-01

A scheme is proposed for high-precision two-dimensional atom localization in a four-level tripod-type atomic system via measurement of the excited state population. It is found that because of the position-dependent atom–field interaction, the precision of 2D atom localization can be significantly improved by appropriately adjusting the system parameters. Our scheme may be helpful in laser cooling or atom nanolithography via high-precision and high-resolution atom localization. (letter)

Evaluation of chromosomal aberrations in radiologists and medical radiographers chronically exposed to ionising radiation

International Nuclear Information System (INIS)

Kasuba, V.; Rozgaj, R.; Jazbec, A.

2005-01-01

Chromosomal aberrations are fairly reliable indicators of damage induced by ionising radiation. This study included 180 radiologists and medical radiographers (technicians) and 90 controls who were not occupationally exposed to ionising radiation. All exposed subjects were routinely monitored with film badge, and none was exposed to a radiation dose exceeding the limit for occupational exposure recommended by the International Commission on Radiological Protection (ICRP). Two hundred metaphases for each person were scored. The frequencies of acentric fragments, dicentrics, ring chromosomes and chromosomal exchanges were determined and compared to those obtained in the control group. Chromosome aberrations were analysed using Poisson regression for profession, age, sex, smoking and years of exposure. Age, smoking, diagnostic exposure to X-rays and occupation were found to correlate with the occurrence of acentric fragments. The influence of exposure duration on the frequency of acentric fragments was greater in medical radiographers than in radiologists. Smoking and sex were found to correlate with the occurrence of dicentric chromosomes, which were more common in men than in women. As chromosome aberrations exceeded the expected level with respect to the absorbed dose, our findings confirm the importance of chromosome analysis as a part of regular medical check-up of subjects occupationally exposed to ionising radiation.(author)

The use of ionising radiation screening devices in airports

International Nuclear Information System (INIS)

Lazo, T.

2010-01-01

Although the NEA generally focuses on radiological protection at nuclear power plants and related facilities, it also addresses other areas of radiological protection of interest to member countries. A particular subject of recent importance concerns the use of ionising radiation screening devices as part of airport security efforts. Modern body scanners can produce human images that can be used to detect weapons that may be hidden beneath a person's clothing. Heightened concerns over terrorist threats to airline flights have prompted many countries to consider the use, or expanded use of body scanners. The use of such devices raises a wide series of questions, some of which concern the radiological protection of those who might be scanned. As such, the Inter-Agency Committee on Radiation Safety (IACRS), an expert body in which the NEA works together with several other international organisations addressing radiological protection issues, recently developed a joint information paper laying out the key radiological protection and other issues that should be or have been considered when making decisions as to whether ionising radiation body scanners should be deployed in airports. This article provides an overview of the information paper. In assessing the possible use of X-ray body scanners, there are two significant radiological protection issues that may be of relevance with regard to the government decision whether their use is justified. First, although the individual exposures are very low, the exposure experienced by the scanned population as a whole will depend on whether all passengers are systematically scanned, or alternatively whether passengers are selected for scanning randomly or on the basis of specific criteria. The manner in which passengers would be selected would need to be known in order to appropriately assess the full radiological protection impact of scanner use. Second, the use of X-ray body scanners on sensitive groups, such as pregnant

Use of ionising radiation

International Nuclear Information System (INIS)

1988-11-01

The Committee has inquired into and reported on the use of ionising radiation for commercial sterilisation, disinfestation, food preservation and other purposes with particular reference to human health and safety; environmental impacts, and adequacy of assessment and regulatory procedures. While food irradiation is apparently commercially successful overseas the application to Australia seems extremely limited - it would be used primarily for disinfestation of insect pests and perhaps to reduce levels of harmful bacteria in a limited range of foods. For other applications there are effective and more economic alternatives. The report reviews other studies of food irradiation and the policies and practices governing its use in other countries. The safety of irradiated food, the radiological safety issues and the regulations which would be required in Australia are dealt with in detail. The Committee recommends, inter alia, that the Australian Government should not approve the irradiation of food in Australia until such time as a routine commercial method of detection has been developed and that the import of caesium 137 for use as an irradiation source in commercial irradiation facilities be prohibited

Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

International Nuclear Information System (INIS)

Najam-ul-Haq, M.; Rainer, M.; Schwarzenauer, T.; Huck, C.W.; Bonn, G.K.

2006-01-01

Biomarkers play a potential role in the early detection and diagnosis of a disease. Our aim is to derivatize carbon nanotubes for exploration of the differences in human body fluids e.g. serum, through matrix assisted laser desorption ionisation/time of flight mass spectrometry (MALDI/TOF-MS) that can be related to disease and subsequently to be employed in the biomarker discovery process. This application we termed as the material enhanced laser desorption ionisation (MELDI). The versatility of this technology is meant to increase the amount of information from biological samples on the protein level, which will have a major impact to serve the cause of diagnostic markers. Serum peptides and proteins are immobilized on derivatized carbon nanotubes, which function as binding material. Protein-loaded suspension is placed on a stainless steel target or buckypaper on aluminum target for direct analysis with MALDI-MS. The elution method to wash the bound proteins from carbon nanotubes was employed to compare with the direct analysis procedure. Elution is carried out by MALDI matrix solution to get them out of the entangled nanotubes, which are difficult to desorb by laser due to the complex nanotube structures. The advantage of these optimized methods compared to the conventional screening methods is the improved sensitivity, selectivity and the short analysis time without prior albumin and immunoglobulin depletion. The comparison of similarly modified diamond and carbon nanotubes exhibit differences in their nature to bind the proteins out of serum due to the differences in their physical characteristics. Infrared (IR) spectroscopy provided hint for the presence of tertiary amine peak at the crucial chemical step of iminodiacetic acid addition to acid chloride functionality on carbon nanotubes. Atomic absorption spectroscopy (AAS) was utilized to quantitatively measure the copper capacity of these derivatized carbon nanotubes which is a direct measure of capacity of

Beam Dynamics in a Muon Ionisation Cooling Channel

International Nuclear Information System (INIS)

Rogers, Chris

2008-01-01

The Neutrino Factory has been proposed as a facility to provide an intense source of neutrinos suitable for the measurement of neutrino oscillation parameters and a possible CP violating phase to unprecedented precision. In the Neutrino Factory, neutrinos are produced by the decay of a muon beam with 20-50 GeV per muon. Initially, the muon beam occupies a large volume in phase space, which must be reduced before the beam can be accelerated. The proposed method to achieve this is to use a solenoidal ionisation colling channel.

Sandia high-power atomic iodine photodissociation laser

International Nuclear Information System (INIS)

Palmer, R.E.; Padrick, T.D.

1975-01-01

One of the more promising candidates for a laser to demonstrate the feasibility of laser fusion is the 1.315 μ atomic iodine laser. In a relatively short time it has been developed into a viable subnanosecond, high energy laser. Although at present the iodine laser cannot equal the output capabilities of a large Nd:glass laser system, there are no foreseeable obstacles in the construction of a 100 psec, 10 KJ or greater atomic iodine laser system. A 100 joule system being constructed at Sandia to investigate many of the scaling parameters essential to the design of a 10 KJ or greater system is described. (U.S.)

Two-dimensional readout in a liquid xenon ionisation chamber

CERN Document Server

Solovov, V; Ferreira-Marques, R; Lopes, M I; Pereira, A; Policarpo, Armando

2002-01-01

A two-dimensional readout with metal strips deposited on both sides of a glass plate is investigated aiming to assess the possibility of its use in a liquid xenon ionisation chamber for positron emission tomography. Here, we present results obtained with an alpha-source. It is shown that position resolution of <=1 mm, fwhm, can be achieved for free charge depositions equivalent to those due to gamma-rays with energy from 220 down to 110 keV.

Towards a Symmetric Momentum Distribution in the Muon Ionisation Cooling Experiment

CERN Document Server

Hansen, O M; Efthymiopoulos, I

2013-01-01

TheMuon Ionisation Cooling Experiment (MICE) is under development at Rutherford Appleton Labratory (UK). It is a proof-of-principle experiment for ionisation cooling, which is a prerequisite for a future Neutrino Factory (NF) or a Muon Collider. The muon beam will have a symmetrical momentum distribution in the cooling channel of theNF [1]. In the MICE beamline pions are captured by a quadrupole triplet, beam momentum is selected by dipole 1 (D1) before the beam traverses the decay solenoid. After the decay solenoid the beam momentum is selected by dipole 2 (D2), the beam is focused in two quadrupole triplets and characterised by time-of-flight (TOF) detectors TOF0 and TOF1 before entering the cooling channel. By doing a so-called D1-scan, where the optics parameters are scaled according to the upstream beam momentum, the purity and momentum distribution of the decay muons are changed. In this paper simulation results from G4Beamline (G4BL) [2] and data from MICE are presented and compared.

Fitness of equipment used for medical exposures to ionising radiation

International Nuclear Information System (INIS)

1998-01-01

The advice in this guidance note is aimed at employers in control of equipment used for medical exposures to ionising radiation and ancillary equipment. This includes NHS trusts, health authorities or boards, private hospitals, clinics, surgeries, medical X-ray facilities in industry, dentists and chiropractors. The guidance should also be useful to radiation protection advisers appointed by such employers. The guidance provides advice on the requirements of regulation 33 of the Ionising Radiations Regulations 1985 (IRR85). In particular, it covers: (a) the selection, installation, maintenance, calibration and replacement of equipment to ensure that it is capable of restricting, so far as reasonably practicable, the medical exposure of any person to the extent that this is compatible with the intended diagnostic or therapeutic purpose; (b) recommended procedures for the definitive calibration of radiotherapy treatment; and (c) the need to investigate incidents involving a malfunction or defect in any 'radiation equipment' which result in medical exposures much greater than intended and to notify the Health and Safety Executive (HSE). 'Medical exposure' is defined in IRR85 as exposure of a person to ionising radiation for the purpose of his or her medical or dental examination or treatment which is conducted under the direction of a suitably qualified person and includes any such examination or treatment conducted for the purposes of research. For convenience, people undergoing medical exposure will be referred to as 'patients' in this guidance. Nothing in this publication is intended to indicate whether or not patients should be informed of any incident resulting from malfunction or defect in equipment used for medical exposure and the possible consequences of that exposure. As stated above, this guidance concerns medical exposures much greater than intended and although exposures much lower than intended can also have serious consequences, the incident would not

Impact ionisation rate calculations in wide band gap semiconductors

International Nuclear Information System (INIS)

Harrison, D.

1998-09-01

Calculations of band-to-band impact ionisation rates performed in the semi-classical Fermi's Golden Rule approximation are presented here for the semiconductors GaAs, In 0.53 Ga 0.47 As and Si 0.5 Ge 0.5 at 300K. The crystal band structure is calculated using the empirical pseudopotential method. To increase the speed with which band structure data at arbitrary k-vectors can be obtained, an interpolation scheme has been developed. Energies are quadratically interpolated on adapted meshes designed to ensure accuracy is uniform throughout the Brillouin zone, and pseudowavefunctions are quadratically interpolated on a regular mesh. Matrix elements are calculated from the pseudowavefunctions, and include the terms commonly neglected in calculations for narrow band gap materials and an isotropic approximation to the full wavevector and frequency dependent dielectric function. The numerical integration of the rate over all distinct energy and wavevector conserving transitions is performed using two different algorithms. Results from each are compared and found to be in good agreement, indicating that the algorithms are reliable. The rates for electrons and holes in each material are calculated as functions of the k-vector of the impacting carriers, and found to be highly anisotropic. Average rates for impacting carriers at a given energy are calculated and fitted to Keldysh-type expressions with higher than quadratic dependence of the rate on energy above threshold being obtained in all cases. The average rates calculated here are compared to results obtained by other workers, with reasonable agreement being obtained for GaAs, and poorer agreement obtained for InGaAs and SiGe. Possible reasons for the disagreement are investigated. The impact ionisation thresholds are examined and k-space and energy distributions of generated carriers are determined. The role of threshold anisotropy, variation in the matrix elements and the shape of the bands in determining

Gene expression analysis after low dose ionising radiation exposure of the developing organism

International Nuclear Information System (INIS)

Abderrafi Benotmane, M.

2007-01-01

Measuring gene expression using microarrays is relevant to many areas of biology and medicine, such as follow up of developmental stages and diseases onset, and treatment study. Since there can be tens of thousands of distinct probes on an array, each micro array experiment can accomplish the equivalent number of genetic tests in parallel. Arrays have therefore dramatically accelerated many types of investigations. For example, microarrays can be used to identify stress response genes by comparing gene expression in challenged versus normal cells. In the Molecular and Cellular Biology lab (MCB), the micro array experiments are performed within the Genomic Platform, fully equipped to analyse either the behaviour of bacteria during long space flight, the effect of low dose ionising radiation on the developing organism in mice, or the human individual radiation sensitivity. For the low dose effect, two main stages of development are of interest; 1) the gastrula stage at which ionizing radiation can induce several malformations. 2) the organogenesis. During brain development, epidemiological studies of the atomic bomb survivors of Hiroshima/Nagasaki showed increased risk of mental retardation in children of women exposed between weeks 8-15 of pregnancy or at a lower extend between weeks 15 to 25

Experimental determination of pcav factors for cylindrical ionisation chambers in electron beams

International Nuclear Information System (INIS)

Palm, Aa.; Mattsson, O.

2000-01-01

The electron beam method recommended for calibrating plane parallel ionisation chambers involves cavity correction factors for cylindrical chambers. The cavity correction factors in the IAEA TRS-381 Code of Practice are based on measurements at R 100 in a PMMA phantom using PMMA cylindrical chambers having different cavity radii. In the present work the recommended data were confirmed for electron beams delivered by modern medical accelerators by using the very same phantom and ionisation chambers that were used in the original work. From another series of measurements, using four specially designed wall-less chambers in a graphite phantom, the linear relation between p cav and the chamber radius that is the basis for the experimental method, was verified. The method was also used to determine the cavity correction factors for a set of Farmer-like graphite chambers placed in water. Compared to the TRS-381 Code of Practice a smaller correction was found for the cavity perturbation for the graphite chambers used in water. (author)

Chapter 8. Ionisation radiation and human organism. Radioactivity of human tissues

International Nuclear Information System (INIS)

Toelgyessy, J.; Harangozo, M.

2000-01-01

This is a chapter of textbook of radioecology for university students. In this chapter authors deal with ionisation radiation and human organism as well as with radioactivity of human tissues. Chapter consists of next parts: (1) Radiation stress of human organism; (2) Radioactivity of human tissues and the factors influencing radioactive contamination; (3) Possibilities of decreasing of radiation stress

Exposure of the French paediatric population to ionising radiation from diagnostic medical procedures in 2010

International Nuclear Information System (INIS)

Etard, Cecile; Aubert, Bernard; Mezzarobba, Myriam; Bernier, Marie-Odile

2014-01-01

Medical examination is the main source of artificial radiation exposure. Because children present an increased sensitivity to ionising radiation, radiology practices at a national level in paediatrics should be monitored. This study describes the ionising radiation exposure from diagnostic medical examinations of the French paediatric population in 2010. Data on frequency of examinations were provided by the French National Health Insurance through a representative sample including 107,627 children ages 0-15 years. Effective doses for each type of procedure were obtained from the published French literature. Median and mean effective doses were calculated for the studied population. About a third of the children were exposed to at least one examination using ionising radiation in 2010. Conventional radiology, dental exams, CT scans and nuclear medicine and interventional radiology represent respectively 55.3%, 42.3%, 2.1% and 0.3% of the procedures. Children 10-15 years old and babies from birth to 1 year are the most exposed populations, with respectively 1,098 and 734 examinations per 1,000 children per year. Before 1 year of age, chest and pelvis radiographs are the most common imaging tests, 54% and 32%, respectively. Only 1% of the studied population is exposed to CT scan, with 62% of these children exposed to a head-and-neck procedure. The annual median and mean effective doses were respectively 0.03 mSv and 0.7 mSv for the exposed children. This study gives updated reference data on French paediatric exposure to medical ionising radiation that can be used for public health or epidemiological purposes. Paediatric diagnostic use appears much lower than that of the whole French population as estimated in a previous study. (orig.)

Exposure of the French paediatric population to ionising radiation from diagnostic medical procedures in 2010

Energy Technology Data Exchange (ETDEWEB)

Etard, Cecile; Aubert, Bernard [Institut de Radioprotection et de Surete Nucleaire, Medical Expertise Unit, Fontenay-aux-Roses (France); Mezzarobba, Myriam [Institut de Radioprotection et de Surete Nucleaire, Laboratory of Epidemiology, Fontenay-aux-Roses (France); Bernier, Marie-Odile [Institut de Radioprotection et de Surete Nucleaire, Laboratory of Epidemiology, Fontenay-aux-Roses (France); Institut de Radioprotection et de Surete Nucleaire, IRSN/PRP-HOM/SRBE/LEPID, Laboratoire d' Epidemiologie, Fontenay-aux-Roses (France)

2014-12-15

Medical examination is the main source of artificial radiation exposure. Because children present an increased sensitivity to ionising radiation, radiology practices at a national level in paediatrics should be monitored. This study describes the ionising radiation exposure from diagnostic medical examinations of the French paediatric population in 2010. Data on frequency of examinations were provided by the French National Health Insurance through a representative sample including 107,627 children ages 0-15 years. Effective doses for each type of procedure were obtained from the published French literature. Median and mean effective doses were calculated for the studied population. About a third of the children were exposed to at least one examination using ionising radiation in 2010. Conventional radiology, dental exams, CT scans and nuclear medicine and interventional radiology represent respectively 55.3%, 42.3%, 2.1% and 0.3% of the procedures. Children 10-15 years old and babies from birth to 1 year are the most exposed populations, with respectively 1,098 and 734 examinations per 1,000 children per year. Before 1 year of age, chest and pelvis radiographs are the most common imaging tests, 54% and 32%, respectively. Only 1% of the studied population is exposed to CT scan, with 62% of these children exposed to a head-and-neck procedure. The annual median and mean effective doses were respectively 0.03 mSv and 0.7 mSv for the exposed children. This study gives updated reference data on French paediatric exposure to medical ionising radiation that can be used for public health or epidemiological purposes. Paediatric diagnostic use appears much lower than that of the whole French population as estimated in a previous study. (orig.)

Search for ionisation density effects in the radiation absorption stage in LiF:Mg,Ti

International Nuclear Information System (INIS)

Nail, I.; Horowitz, Y. S.; Oster, L.; Brandan, M. E.; Rodriguez-Villafuerte, M.; Buenfil, A. E.; Ruiz-Trejo, C.; Gamboa-deBuen, I.; Avila, O.; Tovar, V. M.; Olko, P.; Ipe, N.

2006-01-01

Optical absorption (OA) dose-response of LiF:Mg,Ti (TLD-100) is studied as a function of electron energy (ionisation density) and irradiation dose. Contrary to the situation in thermoluminescence dose-response where the supra-linearity is strongly energy-dependent, no dependence of the OA dose filling constants on energy is observed. This result is interpreted as indicating a lack of competitive process in the radiation absorption stage. The lack of an energy dependence of the dose filling constant also suggests that the charge carrier migration distances are sufficiently large to smear out the differences in the non-uniform distribution of ionisation events created by the impinging gamma/ electron radiation of various energies. (authors)

High U-density nuclear fuel development with application of centrifugal atomization technology

International Nuclear Information System (INIS)

Kim, Chang Kyu; Kim, Ki Hwan; Lee, Don Bae

1997-01-01

In order to simplify the preparation process and improve the properties of uranium silicide fuels prepared by mechanical comminution, a fuel fabrication process applying rotating-disk centrifugal atomization technology was invented in KAERI in 1989. The major characteristic of atomized U 3 Si and U 3 Si 2 powders have been examined. The out-pile properties, including the thermal compatibility between atomized particle and aluminum matrix in uranium silicide dispersion fuels, have generally showed a superiority to the comminuted fuels. Moreover, the RERTR (reduced enrichment for research and test reactors) program, which recently begins to develop very-high-density uranium alloy fuels, including U-Mo fuels, requires the centrifugal atomization process to overcome the contaminations of impurities and the difficulties of the comminution process. In addition, a cooperation with ANL in the U.S. has been performed to develop high-density fuels with an application of atomization technology since December 1996. If the microplate and miniplate irradiation tests of atomized fuels, which have been performed with ANL, demonstrated the stability and improvement of in-reactor behaviors, nuclear fuel fabrication technology by centrifugal atomization could be most-promising to the production method of very-high-uranium-loading fuels. (author). 22 refs., 2 tabs., 12 figs

Design of high-activity single-atom catalysts via n-p codoping

Science.gov (United States)

Wang, Xiaonan; Zhou, Haiyan; Zhang, Xiaoyang; Jia, Jianfeng; Wu, Haishun

2018-03-01

The large-scale synthesis of stable single-atom catalysts (SACs) in experiments remains a significant challenge due to high surface free energy of metal atom. Here, we propose a concise n-p codoping approach, and find it can not only disperse the relatively inexpensive metal, copper (Cu), onto boron (B)-doped graphene, but also result in high-activity SACs. We use CO oxidation on B/Cu codoped graphene as a prototype example, and demonstrate that: (1) a stable SAC can be formed by stronger electrostatic attraction between the metal atom (n-type Cu) and support (p-type B-doped graphene). (2) the energy barrier of the prototype CO oxidation on B/Cu codoped graphene is 0.536 eV by the Eley-Rideal mechanism. Further analysis shows that the spin selection rule can provide well theoretical insight into high activity of our suggested SAC. The concept of n-p codoping may lead to new strategy in large-scale synthesis of stable single-atom catalysts.

Statutory Instruments No 144 of 1994. European Communities (Protection of outside workers from ionising radiation) Regulations, 1994

International Nuclear Information System (INIS)

1994-04-01

These Regulations implement Council Directive 90/641 EURATOM of 4 December, 1990 on the operational protection of outside workers exposed to the risk of ionising radiation during their activities in controlled areas. The Regulations provide for the radiation protection of workers liable to receive an exposure of high radiation levels while working away from their employers' premises. The Regulations also apply to workers who come from, or who go to work in, another Member State of the European Community

High-precision two-dimensional atom localization from four-wave mixing in a double-Λ four-level atomic system

Science.gov (United States)

Shui, Tao; Yang, Wen-Xing; Chen, Ai-Xi; Liu, Shaopeng; Li, Ling; Zhu, Zhonghu

2018-03-01

We propose a scheme for high-precision two-dimensional (2D) atom localization via the four-wave mixing (FWM) in a four-level double-Λ atomic system. Due to the position-dependent atom-field interaction, the 2D position information of the atoms can be directly determined by the measurement of the normalized light intensity of output FWM-generated field. We further show that, when the position-dependent generated FWM field has become sufficiently intense, efficient back-coupling to the FWM generating state becomes important. This back-coupling pathway leads to competitive multiphoton destructive interference of the FWM generating state by three supplied and one internally generated fields. We find that the precision of 2D atom localization can be improved significantly by the multiphoton destructive interference and depends sensitively on the frequency detunings and the pump field intensity. Interestingly enough, we show that adjusting the frequency detunings and the pump field intensity can modify significantly the FWM efficiency, and consequently lead to a redistribution of the atoms. As a result, the atom can be localized in one of four quadrants with holding the precision of atom localization.

Not to confuse 'contaminated' food and 'irradiated' or 'ionised' food

International Nuclear Information System (INIS)

2005-01-01

Food contamination corresponds to the undesired presence of radioactive products in food, while irradiation is a process to which food can be deliberately submitted to improve its preservation or hygiene. This publication explains this difference. It describes the process, physical effects and health impacts of radioactive contamination of food. It briefly describes irradiation or ionisation processes, their objectives, doses of ionising radiations used on food products, undesired and harmful effects. It also indicates food products concerned by these irradiation processes, and the associated legal framework, evokes the lack of information of consumers regarding such practices, briefly evokes risks associated with irradiation installations, and indicates where these installations are located in France

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

Science.gov (United States)

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

Calculated ionisation potentials to determine the oxidation of vanillin precursors by lignin peroxidase.

NARCIS (Netherlands)

Have, ten R.; Rietjens, I.M.C.M.; Hartmans, S.; Swarts, H.J.; Field, J.A.

1998-01-01

In view of the biocatalytic production of vanillin, this research focused on the lignin peroxidase (LiP) catalysed oxidation of naturally occurring phenolic derivatives: O-methyl ethers, O-acetyl esters, and O-glucosyl ethers. The ionisation potential (IP) of a series of model compounds was

The effect of an alternating electric field on a totally ionised plasma; Action d'un champ electrique alternatif sur un plasma totalement ionise

Energy Technology Data Exchange (ETDEWEB)

Baglin, H; Brin, A; Ozias, Y; Salmon, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Delcroix, J L [Ecole Normale Superieure, 75 - Paris (France)

1960-07-01

The equation giving the distribution function of the electrons in a steady-state, for a fully ionized plasma in an a.c. field, are provided from the Fokker-Planck equation. The electric conductivity is complex and depends on the frequency. (author) [French] L'equation qui donne la fonction de distribution des electrons dans un etat stationnaire pour un plasma totalement ionise dans un champ electrique alternatif est fournie par l'equation de Fokker-Planck. La conductibilite electrique est complexe et depend de la frequence. (auteur)

Experimental investigation of the utilisation of ionisation gauges for leak detection

CERN Document Server

Benvenuti, C

1972-01-01

A description is given of a method of leak detecting applicable to the ISR (CERN) vacuum system after bakeout. This method, based on the enhanced indication of an ionisation gauge obtained when replacing the air around the leak by Argon, affords a detection efficiency not lower than that obtainable by means of a traditional leak detector; furthermore it does not introduce contamination risks after bakeout. (4 refs).

Guideline for the licensing of various designs of ionisation smoke alarms

International Nuclear Information System (INIS)

1978-01-01

The purpose of the guideline is to set up criteria for the construction licensing of ionisation smoke alarms and to determine their use. This guarantees that only those ISA are licensed which correspond to the level of science and technology and that the ISA to be licensed fulfills the demands of radiation protection. The recommendations of OECD/NEA are also born in mind. (orig./HP) [de

The Chocolate Shop and Atomic Orbitals: A New Atomic Model Created by High School Students to Teach Elementary Students

Science.gov (United States)

Liguori, Lucia

2014-01-01

Atomic orbital theory is a difficult subject for many high school and beginning undergraduate students, as it includes mathematical concepts not yet covered in the school curriculum. Moreover, it requires certain ability for abstraction and imagination. A new atomic orbital model "the chocolate shop" created "by" students…

Formation of cold molecules through the photo-association of cold atoms of Cesium. Existence of long range forces between between cold excited atoms of Cesium

International Nuclear Information System (INIS)

Comparat, D.

1999-09-01

This thesis deals with the experimental study and the theoretical interpretation of the processes involved in photo-association and the formation of cold caesium molecules. It also presents a study of the dipolar forces between a pair of cold excited caesium atoms. We present here the first photo-association experiment on cold caesium atoms: two cold atoms absorb a photon to form an excited electronically excited molecules in a rotation-vibration level. The first production of cold molecules which was realised experimentally, after the spontaneous deexcitation of the photo-associated molecules, is described, stressing the role of the potential well of the molecular states O g - (6s+6p 3/2 ) or 1 u (6s+6p 3/2 ) of caesium. The detection of the formed caesium molecules is based on a two-photons resonant ionisation that creates Cs 2 + ions, afterwards selectively detected. Temperatures around 20-200 μK have been measured. The photo-associative spectroscopy is described on the theoretical point of view: a detailed theoretical study allows to calculate precisely the asymptotic parts of the potential curves. On the experimental point of view, we present the spectroscopy of the extern potential well of the caesium state O g - (6s+6p 3/2 ) and the construction of an effective potential curve of the RKR type. A unified theory of photo-association in weak field, considered as a collision assisted by laser, is developed. The cold atoms experiments allow to study and control the collision between two atoms whose mutual interaction is of the dipole-dipole type. Two different physical systems are studied: a sample of Rydberg atoms, and the photo-association process which is a laser-assisted collision. A modification of the motion of one pair of atoms makes it possible to control the bipolar forces and to choose the atoms relative speeds. (author)

Martian sub-surface ionising radiation: biosignatures and geology

Directory of Open Access Journals (Sweden)

J. M. Ward

2007-07-01

Full Text Available The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionising radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Here, we present modelling results of the absorbed radiation dose as a function of depth through the Martian subsurface, suitable for calculation of biomarker persistence. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments.

We present calculations of the dose-depth profile in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost, solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude, and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and discuss particle deflection by the crustal magnetic fields.

Bremsstrahlung spectra for Al, Cs, and Au atoms in high-temperature, high-density plasmas

International Nuclear Information System (INIS)

Kim, L.; Pratt, R.H.; Tseng, H.K.

1985-01-01

Results are presented from a numerical calculation for the bremsstrahlung spectrum and Gaunt factors of Al, Cs, and Au atoms in high-temperature (-T), high-density (-rho) plasmas. Plasma temperatures kT = 0.1 and 1.0 keV and plasma densities rho = rho 0 (the normal solid density) and rho = 100rho 0 are considered. This allows us to determine the generality and identify the origins of features which we had previously identified in calculations for Cs. We also now present results for the total energy loss of an electron in such a plasma. We use a relativistic multipole code which treats the bremsstrahlung process as a single-electron transition in a static screened central potential. We take for the static potential corresponding to an atom in a hot dense plasma the finite-temperature, finite-density Thomas-Fermi model. This approach corresponds to an average atom in local thermodynamic equilibrium. In comparison to isolated-neutral-atom results we observe general suppression of cross sections and a particular suppression in the tip region of the spectrum. Within this model, both superscreening and shape resonances are found in the circumstances of extreme density. At more normal densities and except for the soft-photon end, the spectrum at these energies for an atom in a hot plasma (characterized by an average degree of ionization) can be well represented by the spectrum of the corresponding isolated ion, which has a similar potential shape at the distances which characterize the process

The philosophy and assumptions underlying exposure limits for ionising radiation, inorganic lead, asbestos and noise

International Nuclear Information System (INIS)

Akber, R.

1996-01-01

Full text: A review of the literature relating to exposure to, and exposure limits for, ionising radiation, inorganic lead, asbestos and noise was undertaken. The four hazards were chosen because they were insidious and ubiquitous, were potential hazards in both occupational and environmental settings and had early and late effects depending on dose and dose rate. For all four hazards, the effect of the hazard was enhanced by other exposures such as smoking or organic solvents. In the cases of inorganic lead and noise, there were documented health effects which affected a significant percentage of the exposed populations at or below the [effective] exposure limits. This was not the case for ionising radiation and asbestos. None of the exposure limits considered exposure to multiple mutagens/carcinogens in the calculation of risk. Ionising radiation was the only one of the hazards to have a model of all likely exposures, occupational, environmental and medical, as the basis for the exposure limits. The other three considered occupational exposure in isolation from environmental exposure. Inorganic lead and noise had economic considerations underlying the exposure limits and the exposure limits for asbestos were based on the current limit of detection. All four hazards had many variables associated with exposure, including idiosyncratic factors, that made modelling the risk very complex. The scientific idea of a time weighted average based on an eight hour day, and forty hour week on which the exposure limits for lead, asbestos and noise were based was underpinned by neither empirical evidence or scientific hypothesis. The methodology of the ACGIH in the setting of limits later brought into law, may have been unduly influenced by the industries most closely affected by those limits. Measuring exposure over part of an eight hour day and extrapolating to model exposure over the longer term is not the most effective way to model exposure. The statistical techniques used

Measurement of the total ionisation intensity near the ground and separation of the various components; Mesure de l'intensite totale d'ionisation au voisinage du sol et separation de ses differentes composantes

Energy Technology Data Exchange (ETDEWEB)

Grevet, Ph [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1965-06-01

The aim of this work is to measure the total amount of ion-pairs produced in the air per unit time and unit volume. It is possible, furthermore, by using continuous recording to study the variations in the ionisation due to {alpha}, {beta} and {gamma} radiation at a height of one metre. The apparatus which has been developed consists of two chambers of 120 litres: one, hermetically sealed detects the {gamma} component, the other with a circulation of the ambient air detects the {alpha} and {gamma}; it is thus possible by difference to evaluate the {alpha} component. The chambers and the associated electronic equipment have been designed for continuous operation in the open air. Another chamber without walls can be used for measuring directly the total ionisation intensity and from this an approximate calculation may be made of the {beta} component. A series of recordings has been made near Saclay where the natural radio-activity level is moderate, and in regions of low and high activity (near the sea and in the CEA's mining divisions). It has thus been possible to show the variation in the {gamma} component as a function of the geographic position of the measurement (from 3.7 to 6.3 l/cm{sup 3}.s), the very large variations of the {alpha} component at a given place with changing meteorological conditions (from 1.5 to 45 l/cm{sup 3}.s at Saclay for example) an the far smaller variations in the {beta} component. (author) [French] Le but de ce travail est de mesurer la quantite totale de paires d'ions produite dans l'air par unite de temps et de volume. Des enregistrements continus permettent, de plus, d'etudier les variations a 1 m du sol de cette ionisation due aux rayonnements {alpha}, {beta} et {gamma}. L'appareillage mis au point est forme de deux chambres de 120 litres: l'une hermetiquement fermee detecte la composante {gamma}; l'autre avec circulation de l'air ambiant detecte {alpha} + {gamma} ce qui permet d'evaluer par difference la composante {alpha}. Les

A high resolution ion microscope for cold atoms

International Nuclear Information System (INIS)

Stecker, Markus; Schefzyk, Hannah; Fortágh, József; Günther, Andreas

2017-01-01

We report on an ion-optical system that serves as a microscope for ultracold ground state and Rydberg atoms. The system is designed to achieve a magnification of up to 1000 and a spatial resolution in the 100 nm range, thereby surpassing many standard imaging techniques for cold atoms. The microscope consists of four electrostatic lenses and a microchannel plate in conjunction with a delay line detector in order to achieve single particle sensitivity with high temporal and spatial resolution. We describe the design process of the microscope including ion-optical simulations of the imaging system and characterize aberrations and the resolution limit. Furthermore, we present the experimental realization of the microscope in a cold atom setup and investigate its performance by patterned ionization with a structure size down to 2.7 μ m. The microscope meets the requirements for studying various many-body effects, ranging from correlations in cold quantum gases up to Rydberg molecule formation. (paper)

Collection efficiency of charges in ionization chambers in presence of constant or variable radiation intensity; Efficacite de la collection des charges dans les chambres d'ionisation en presence d'une intensite de rayonnement ionisant constante ou variable

Energy Technology Data Exchange (ETDEWEB)

Decuyper, J [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1970-07-01

The theoretical and experimental study of the collection of carriers built up by ionization in standard chambers, is made by varying the value of different acting parameters. In the presence of constant ionization intensity and under a D.C. and A.C. voltage, the effect of geometry, recombination, diffusion and attachment is analyzed. The compensation of thermal neutron D.C. chambers is equally considered. Under a time dependent ionization intensity and D.C. voltage, is then studied the effect of recombination on current response, and on the collection efficiency of all formed charges. (author) [French] L'etude theorique et experimentale de la collection des porteurs crees par ionisation dans les chambres couramment utilisees est entreprise en fonction de la valeur des differents parametres agissants. En presence d'une ionisation constante et sous une tension d'alimentation d'abord continue puis alternative, on analyse l'influence de la geometrie, de la recombinaison, de la diffusion et de l'attachement. La compensation des chambres a courant continu de mesure neutronique est egalement examinee. Ensuite, sous une intensite d'ionisation variable dans le temps et en alimentation continue, on etudie l'effet de la recombinaison sur la reponse en courant et sur l'efficacite de la collection de la charge totale liberee. (auteur)

Documentation of Occupational Accidents and Diseases caused by Ionising Radiation

International Nuclear Information System (INIS)

Fehringer, F.; Seitz, G.

2004-01-01

. One of the major goals of the institutions for statutory accident insurance is the prevention of occupational diseases. To perform a successful prevention work it is necessary not only to count the number of accidents or diseases in the various working fields but to look for details of the conditions of work and the human response to those conditions. The institutions for statutory accident insurance have engaged the institution for statutory accident insurance in the precision engineering and electrical industry to carry out documentation, in form of a data bank, for all cases of occupational diseases which could be caused by ionising radiation. Those are not only the cases which are accepted as occupational disease but also the cases where a suspicion of an occupational disease is announced but finally rejected. At the moment about 1700 cases are included in the data bank. For preserving the anonymity information to name and residence are deleted. Various data to one single case are linked by a case-specific key-number. Information to occupation and field of working, to details of a possible exposure to ionising radiation like kind of radiation, time and duration of radiation, exposure of the whole body or of parts of the body and whole body or organ doses are collected. Additional information refers to medical aspects like diagnosis and date of diagnosis. (Author)

A study on the health of the employees of Atomic Energy of Canada Limited. III

International Nuclear Information System (INIS)

Johnston, L.H.; Werner, M.M.

1987-01-01

The Atomic Energy of Canada Ltd (AECL) Employee Health Study commenced in 1980 July following the issue of a Company-Wide General Notice of 1980 April by the President of Atomic Energy of Canada Limited, Mr. James Donnelly. The study was set up to determine the causes of death of the AECL study population as compared to a similar group in the general population and to determine if there is a relationship between cause of death and occupational exposure to ionising radiation. Previous AECL reports have outlined how the study has been set up and implemented. The purpose of this report is to describe the reasons for and the methods of upgrading the data base for the AECL Employee Health Study. Some description of procedures used during the first linkage and recommendations for future linkages are included

Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry.

Science.gov (United States)

Mämmelä, P; Savolainen, H; Lindroos, L; Kangas, J; Vartiainen, T

2000-09-01

Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid.

The design of a calorimetric standard of ionising radiation absorbed dose

International Nuclear Information System (INIS)

Huntley, R.B.

1981-05-01

The design of a calorimetric working standard of ionising radiation absorbed dose is discussed. A brief history of the appropriate quantities and units of measurement is given. Detailed design considerations follow a summary of the relevant literature. The methods to be used to relate results to national standards of measurement are indicated, including the need for various correction factors. A status report is given on the construction and testing program

A preliminary inter-centre comparison study for photon, thermal neutron and epithermal neutron responses of two pairs of ionisation chambers used for BNCT

International Nuclear Information System (INIS)

Roca, Antoaneta; Liu, Yuan-Hao; Wojnecki, Cecile; Green, Stuart; Nievaart, Sander; Ghani, Zamir; Moss, Ray

2009-01-01

The dual ionisation chamber technique is the recommended method for mixed field dosimetry of epithermal neutron beams. This paper presents initial data from an ongoing inter-comparison study involving two identical pairs of ionisation chambers used at the BNCT facilities of Petten, NL and of University of Birmingham, UK. The goal of this study is to evaluate the photon, thermal neutron and epithermal neutron responses of both pairs of TE(TE) (Exradin T2 type) and Mg(Ar) (Exradin M2 type) ionisation chambers in similar experimental conditions. At this stage, the work has been completed for the M2 type chambers and is intended to be completed for the T2 type chambers in the near future.

High data rate atom interferometric device

Science.gov (United States)

Biedermann, Grant; McGuinness, Hayden James Evans; Rakholia, Akash

2015-07-21

A light-pulse atomic interferometry (LPAI) apparatus is provided. The LPAI apparatus comprises a vessel, two sets of magnetic coils configured to magnetically confine an atomic vapor in two respective magneto-optical traps (MOTs) within the vessel when activated, and an optical system configured to irradiate the atomic vapor within the vessel with laser radiation that, when suitably tuned, can launch atoms previously confined in each of the MOTs toward the other MOT. In embodiments, the magnetic coils are configured to produce a magnetic field that is non-zero at the midpoint between the traps. In embodiments, the time-of-flight of the launched atoms from one MOT to the other is 12 ms or less. In embodiments, the MOTs are situated approximately 36 mm apart. In embodiments, the apparatus is configured to activate the magnetic coils according to a particular temporal magnetic field gradient profile.

The ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions

Energy Technology Data Exchange (ETDEWEB)

Herbschleb, C. T.; Tuijn, P. C. van der; Roobol, S. B.; Navarro, V.; Bakker, J. W.; Liu, Q.; Stoltz, D.; Cañas-Ventura, M. E.; Verdoes, G.; Spronsen, M. A. van; Bergman, M.; Crama, L.; Taminiau, I.; Frenken, J. W. M., E-mail: frenken@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. box 9504, 2300 RA Leiden (Netherlands); Ofitserov, A.; Baarle, G. J. C. van [Leiden Probe Microscopy B.V., J.H. Oortweg 21, 2333 CH Leiden (Netherlands)

2014-08-15

To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions.

Compensator design for improved counterbalancing in high speed atomic force microscopy

OpenAIRE

Bozchalooi, I. S.; Youcef-Toumi, K.; Burns, D. J.; Fantner, G. E.

2011-01-01

High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, ...

Non-targeted effects of ionising radiation. Proceedings of the RISC-RAD specialised training course

International Nuclear Information System (INIS)

Belyakov, O.V.

2008-12-01

The training course 'Non-targeted effects of ionising radiation' took place at the STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland 14-16 February 2005. Proceeding of this course is collected in this volume. The idea of the course was to convene a number of scientists leading in the area of non-targeted effects of ionising radiation with the aim to outline their visions for the role of these effects and outline the future directions of radiation research on the basis of their expertise. The course was supported by the RISC-RAD IP FI6R-CT-2003-508842, Euratom specific programme for research and training on nuclear energy, 6th FP of the EC. The main objectives of the training course were: (1) to clarify the mechanisms of non-targeted effects, in particular, bystander effects, genomic instability and adaptive response; (2) to look if and how non-targeted effects modulate the cancer risk in the low dose region, and whether they relate to protective or harmful functions; (3) to clarify if ionising radiation can cause non-cancer diseases or beneficial effects at low and intermediate doses; (4) address the issue of individual susceptibility and other factors modifying non-targeted responses; (5) attempt to assess the relevance of non-targeted effects for radiation protection and to set the scientific basis for a modern, more realistic, radiation safety system; (6) and finally to contribute to the conceptualisation of a new paradigm in radiation biology that would cover both the classical direct (DNA-targeted) and non-targeted (indirect) effects

On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere – a Cassini case study

Directory of Open Access Journals (Sweden)

G. R. Lewis

2007-11-01

Full Text Available We present data from the sixth Cassini flyby of Titan (T5, showing that the magnetosphere of Saturn strongly interacts with the moon's ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement with the altitude structure of the ionosphere. Furthermore, we suggest that the dense and cold exo-ionosphere (from the exobase at 1430 km and outward to several Titan radii from the surface can be explained by magnetospheric forcing and other transport processes whereas exospheric ionisation by impacting low energy electrons seems to play a minor role.

High efficiency atomic hydrogen source

International Nuclear Information System (INIS)

Lagomarsino, V.; Bassi, D.; Bertok, E.; De Paz, M.; Tommasini, F.

1974-01-01

This work presents preliminary results of research intended to produce a M.W. discharge atomic hydrogen source with good dissociation at pressures larger than 10 torr. Analysis of the recombination process at these pressures shows that the volume recombination by three body collisions may be more important than wall recombination or loss of atoms by diffusion and flow outside the discharge region

Cold atomic beams of high brightness

International Nuclear Information System (INIS)

Rozhdestvensky, Yu V

2004-01-01

The possibility is studied for obtaining intense cold atomic beams by using the Renyi entropy to optimise the laser cooling process. It is shown in the case of a Gaussian velocity distribution of atoms, the Renyi entropy coincides with the density of particles in the phase space. The optimisation procedure for cooling atoms by resonance optical radiation is described, which is based on the thermodynamic law of increasing the Renyi entropy in time. Our method is compared with the known methods for increasing the laser cooling efficiency such as the tuning of a laser frequency in time and a change of the atomic transition frequency in an inhomogeneous transverse field of a magnetic solenoid. (laser cooling)

Formation of cold molecules through the photo-association of cold atoms of Cesium. Existence of long range forces between between cold excited atoms of Cesium; Formation de molecules froides par photoassociation d'atomes froids de cesium. Mise en evidence de forces a longue portee entre atomes froids excites de cesium

Energy Technology Data Exchange (ETDEWEB)

Comparat, D

1999-09-01

This thesis deals with the experimental study and the theoretical interpretation of the processes involved in photo-association and the formation of cold caesium molecules. It also presents a study of the dipolar forces between a pair of cold excited caesium atoms. We present here the first photo-association experiment on cold caesium atoms: two cold atoms absorb a photon to form an excited electronically excited molecules in a rotation-vibration level. The first production of cold molecules which was realised experimentally, after the spontaneous deexcitation of the photo-associated molecules, is described, stressing the role of the potential well of the molecular states O{sub g}{sup -}(6s+6p{sub 3/2}) or 1{sub u} (6s+6p{sub 3/2}) of caesium. The detection of the formed caesium molecules is based on a two-photons resonant ionisation that creates Cs{sub 2}{sup +} ions, afterwards selectively detected. Temperatures around 20-200 {mu}K have been measured. The photo-associative spectroscopy is described on the theoretical point of view: a detailed theoretical study allows to calculate precisely the asymptotic parts of the potential curves. On the experimental point of view, we present the spectroscopy of the extern potential well of the caesium state O{sub g}{sup -}(6s+6p{sub 3/2}) and the construction of an effective potential curve of the RKR type. A unified theory of photo-association in weak field, considered as a collision assisted by laser, is developed. The cold atoms experiments allow to study and control the collision between two atoms whose mutual interaction is of the dipole-dipole type. Two different physical systems are studied: a sample of Rydberg atoms, and the photo-association process which is a laser-assisted collision. A modification of the motion of one pair of atoms makes it possible to control the bipolar forces and to choose the atoms relative speeds. (author)

Thermal ionisation mass spectrometry (TIMS): what, how and why?

International Nuclear Information System (INIS)

Aggarwal, S.K.

2002-01-01

Thermal ionisation mass spectrometry (TIMS) is one of the oldest mass spectrometric techniques, which has been used for determining the isotopic composition and concentration of different elements using isotope dilution. In spite of the introduction of many other inorganic mass spectrometric techniques like spark source mass spectrometry (SSMS), glow discharge mass spectrometry (GDMS), inductively coupled plasma-mass spectrometry (ICP-MS), secondary ion mass spectrometry (SIMS), the TIMS technique plays the role of a definitive analytical methodology and still occupies a unique position in terms of its capabilities with respect to precision and accuracy as well as sensitivity

The Radman Guide to the Ionising Radiations Regulations 1985

International Nuclear Information System (INIS)

Hughes, D.

1986-01-01

The guidance given in the handbook is of general nature for the assistance of senior managers and administrators (rather than scientific or technical staff), involved in or responsible for work with ionising radiations. The subject is dealt with under the following headings: 1) Digest of the Regulations. 2) Application of Regulations (division of responsibility between employer, employee, supervisors, medical personnel etc., role of the Health and Safety Executive.) 3) Designation of work areas and persons 4) Radiation Protection Supervisors and Local Rules 5) Hazard assessments and contingency plans 6) Notifications and Record Keeping 7) Routines in source control. (UK)

High Fidelity Simulation of Primary Atomization in Diesel Engine Sprays

Science.gov (United States)

Ivey, Christopher; Bravo, Luis; Kim, Dokyun

2014-11-01

A high-fidelity numerical simulation of jet breakup and spray formation from a complex diesel fuel injector at ambient conditions has been performed. A full understanding of the primary atomization process in fuel injection of diesel has not been achieved for several reasons including the difficulties accessing the optically dense region. Due to the recent advances in numerical methods and computing resources, high fidelity simulations of atomizing flows are becoming available to provide new insights of the process. In the present study, an unstructured un-split Volume-of-Fluid (VoF) method coupled to a stochastic Lagrangian spray model is employed to simulate the atomization process. A common rail fuel injector is simulated by using a nozzle geometry available through the Engine Combustion Network. The working conditions correspond to a single orifice (90 μm) JP-8 fueled injector operating at an injection pressure of 90 bar, ambient condition at 29 bar, 300 K filled with 100% nitrogen with Rel = 16,071, Wel = 75,334 setting the spray in the full atomization mode. The experimental dataset from Army Research Lab is used for validation in terms of spray global parameters and local droplet distributions. The quantitative comparison will be presented and discussed. Supported by Oak Ridge Associated Universities and the Army Research Laboratory.

Transcription-based model for the induction of chromosomal exchange events by ionising radiation

International Nuclear Information System (INIS)

Radford, I.A.

2003-01-01

The mechanistic basis for chromosomal aberration formation, following exposure of mammalian cells to ionising radiation, has long been debated. Although chromosomal aberrations are probably initiated by DNA double-strand breaks (DSB), little is understood about the mechanisms that generate and modulate DNA rearrangement. Based on results from our laboratory and data from the literature, a novel model of chromosomal aberration formation has been suggested (Radford 2002). The basic postulates of this model are that: (1) DSB, primarily those involving multiple individual damage sites (i.e. complex DSB), are the critical initiating lesion; (2) only those DSB occurring in transcription units that are associated with transcription 'factories' (complexes containing multiple transcription units) induce chromosomal exchange events; (3) such DSB are brought into contact with a DNA topoisomerase I molecule through RNA polymerase II catalysed transcription and give rise to trapped DNA-topo I cleavage complexes; and (4) trapped complexes interact with another topo I molecule on a temporarily inactive transcription unit at the same transcription factory leading to DNA cleavage and subsequent strand exchange between the cleavage complexes. We have developed a method using inverse PCR that allows the detection and sequencing of putative ionising radiation-induced DNA rearrangements involving different regions of the human genome (Forrester and Radford 1998). The sequences detected by inverse PCR can provide a test of the prediction of the transcription-based model that ionising radiation-induced DNA rearrangements occur between sequences in active transcription units. Accordingly, reverse transcriptase PCR was used to determine if sequences involved in rearrangements were transcribed in the test cells. Consistent with the transcription-based model, nearly all of the sequences examined gave a positive result to reverse transcriptase PCR (Forrester and Radford unpublished)

Grazing incidence collisions of ions and atoms with surfaces: from charge exchange to atomic diffraction; Collisions rasantes d'ions ou d'atomes sur les surfaces: de l'echange de charge a la diffraction atomique

Energy Technology Data Exchange (ETDEWEB)

Rousseau, P

2006-09-15

This thesis reports two studies about the interaction with insulating surfaces of keV ions or atoms under grazing incidence. The first part presents a study of charge exchange processes occurring during the interaction of singly charged ions with the surface of NaCl. In particular, by measuring the scattered charge fraction and the energy loss in coincidence with electron emission, the neutralization mechanism is determined for S{sup +}, C{sup +}, Xe{sup +}, H{sup +}, O{sup +}, Kr{sup +}, N{sup +}, Ar{sup +}, F{sup +}, Ne{sup +} and He{sup +}. These results show the importance of the double electron capture as neutralization process for ions having too much potential energy for resonant capture and not enough for Auger neutralization. We have also studied the ionisation of the projectile and of the surface, and the different Auger-like neutralization processes resulting in electron emission, population of conduction band or excited state. For oxygen scattering, we have measured an higher electron yield in coincidence with scattered negative ion than with scattered atom suggesting the transient formation above the surface of the oxygen doubly negative ion. The second study deals with the fast atom diffraction, a new phenomenon observed for the first time during this work. Due to the large parallel velocity, the surface appears as a corrugated wall where rows interfere. Similarly to the Thermal Atom Scattering the diffraction pattern corresponds to the surface potential and is sensitive to vibrations. We have study the H-NaCl and He-LiF atom-surface potentials in the 20 meV - 1 eV range. This new method offers interesting perspectives for surface characterisation. (author)

Thermoluminescent properties of CVD diamond: applications to ionising radiation dosimetry; Proprietes thermoluminescentes du diamant CVD: applications a la dosimetrie des rayonnements ionisants

Energy Technology Data Exchange (ETDEWEB)

Petitfils, A

2007-09-15

Remarkable properties of synthetic diamond (human soft tissue equivalence, chemical stability, non-toxicity) make this material suitable for medical application as thermoluminescent dosimeter (TLD). This work highlights the interest of this material as radiotherapy TLD. In the first stage of this work, we looked after thermoluminescent (TL) and dosimetric properties of polycrystalline diamond made by Chemically Vapor Deposited (CVD) synthesis. Dosimetric characteristics are satisfactory as TLD for medical application. Luminescence thermal quenching on diamond has been investigated. This phenomenon leads to a decrease of dosimetric TL peak sensitivity when the heating rate increases. The second part of this work analyses the use of synthetic diamond as TLD in radiotherapy. Dose profiles, depth dose distributions and the cartography of an electron beam obtained with our samples are in very good agreement with results from an ionisation chamber. It is clearly shown that CVD) diamond is of interest to check beams of treatment accelerators. The use of these samples in a control of treatment with Intensity Modulated Radiation Therapy underlines good response of synthetic diamond in high dose gradient areas. These results indicate that CVD diamond is a promising material for radiotherapy dosimetry. (author)

Rapid and simultaneous determination of polychlorinated biphenyls and their main metabolites (hydroxylated and methyl sulfonyl) by gas chromatography coupled to mass spectrometry: Comparison of different ionisation modes

International Nuclear Information System (INIS)

Castro-Puyana, M.; Herrero, L.; González, M.J.; Gómara, B.

2013-01-01

Graphical abstract: -- Highlights: •Simultaneous determination of PCB, OH-PCBs and MeSO 2 -PCBs in a single GC–MS run. •Two different ionisation modes (EI and ECNI) are studied and compared. •The analytical characterisation of both methods is satisfactory. •Better LODs are achieved using ECNI-MS as ionisation mode. •The developed methodology is successfully applied to fish liver oil. -- Abstract: Instrumental methods based on gas chromatography coupled to mass spectrometry (GC–MS) have been developed and compared using two different MS ionisation modes, electron impact (EI) and electron capture negative ionisation (ECNI), for the fast, quantitative and simultaneous determination of polychlorinated biphenyls (PCBs) and their main metabolites (hydroxylated PCBs, OH-PCBs, and methyl sulfone PCBs, MeSO 2 -PCBs). Parameters affecting chromatographic separation and MS detection were evaluated in order to achieve the highest selectivity and sensitivity for both operation modes. The analytical characteristics of the developed methods were studied and compared in terms of linear range, limits of detection (LODs), limits of quantification (LOQs), and instrumental precision (repeatability and intermediate precision). Both ionisation methods showed similar precision, being relative standard deviations (RSD, %) lower than 9% and 14% for repeatability and intermediate precision, respectively. However, better LODs (from 0.01 to 0.14 pg injected for the three families of congeners studied) were achieved using ECNI-MS as ionisation mode. The suitability of the developed method was demonstrated through their application to fish liver oil samples

Revisiting Bragg's X-ray microscope: scatter based optical transient grating detection of pulsed ionising radiation.

Science.gov (United States)

Fullagar, Wilfred K; Paganin, David M; Hall, Chris J

2011-06-01

Transient optical gratings for detecting ultrafast signals are routine for temporally resolved photochemical investigations. Many processes can contribute to the formation of such gratings; we indicate use of optically scattering centres that can be formed with highly variable latencies in different materials and devices using ionising radiation. Coherent light scattered by these centres can form the short-wavelength-to-optical-wavelength, incoherent-to-coherent basis of a Bragg X-ray microscope, with inherent scope for optical phasing. Depending on the dynamics of the medium chosen, the way is open to both ultrafast pulsed and integrating measurements. For experiments employing brief pulses, we discuss high-dynamic-range short-wavelength diffraction measurements with real-time optical reconstructions. Applications to optical real-time X-ray phase-retrieval are considered. Copyright © 2010 Elsevier B.V. All rights reserved.

First Glossary of Modern Physics and Ionising Radiation Protection in Croatian

International Nuclear Information System (INIS)

Nodilo, M.; Petkovic, T.

2011-01-01

Motivation and encouragement for the Glossary were given as the research theme for the joint seminar between the Faculty of Electrical Engineering and Computing and Rudjer Boskovic Institute, within a postgraduate course subject ''Detectors and electronic instrumentation for particle physics''. A basic motivation is due to a lack of specialized literature in Croatian language in the field of protection of ionising radiation as well as the incompleteness of Croatian terminology in the same field. That is a general problem all over the World because the most glossaries are usually connected either with nuclear power plants or with an application of ionising radiation in medicine. On the other hand, a necessity for the specialized literature for radiation protection which follows a development of modern particle physics and its detection technique is rapidly growing up. A work and development on the Glossary were faced with serious difficulties, since various translations of foreign words and acronyms have already been used by various authors in Croatian literature. Different interpretations of the same term or concept, from diverse sources, had to be very often reconciled. However, the biggest challenge was finding proper Croatian words for the foreign terms, concepts, properties, and quantities which have not yet been commonly used so far in Croatian papers or/and Croatian legislative acts. According to our knowledge this seems to be the first comprehensive Glossary, describing the field of ionising radiation protection and bringing of 300 related entries (terms and guidelines). That is, certainly, the first characteristic Thesaurus in Croatian which includes background of modern physics and chemistry, particle phenomenology and its measurement, all dedicated to the radiological protection of workers, environment and people of the World. A Glossary brings a wide spectrum of terms of broad area of chemistry, radiation protection, nuclear and particle physics. A

Quantum-orbit theory of high-order atomic processes in strong fields

International Nuclear Information System (INIS)

Milosevic, D.B.

2005-01-01

Full text: Atoms submitted to strong laser fields can emit electrons and photons of very high energies. These processes find a highly intuitive and also quantitative explanation in terms of Feynman's path integral and the concept of quantum orbits. The quantum-orbit formalism is particularly useful for high-order atomic processes in strong laser fields. For such multi-step processes there is an intermediate step during which the electron is approximately under the influence of the laser field only and can absorb energy from the field. This leads to the appearance of the plateau structures in the emitted electron or photon spectra. Usual examples of such processes are high-order harmonic generation (HHG) and high-order above threshold ionization (HATI). These structures were also observed in high-order above-threshold detachment, laser-assisted x-ray-atom scattering, laser-assisted electron-ion recombination, and electron-atom scattering. We will present high-order strong-field approximation (SFA) and show how the quantum-orbit formalism follows from it. This will be done for various above-mentioned processes. For HHG a classification of quantum orbits will be given [10) and generalized to the presence of a static field. The low-energy part of the HHG spectra and the enhancement of HHG near the channel closings can be explained taking into account a large number of quantum orbits. For HATI we will concentrate on the case of few-cycle laser pulse. The influence of the carrier-envelope relative phase on the HATI spectrum can easily be explained in terms of quantum orbits. The SFA and the quantum-orbit results will be compared with the results obtained by Dieter Bauer using ab initio solutions of the time-dependent Schroedinger equation. It will be shown that the Coulomb effects are important for low-energy electron spectra. Refs. 11 (author)

Atomic processes in high temperature plasmas

International Nuclear Information System (INIS)

Hahn, Y.

1990-03-01

Much theoretical and experimental efforts have been expended in recent years to study those atomic processes which are specially relevant to understanding high temperature laboratory plasmas. For magnetically confined fusion plasmas, the temperature range of interest spans from the hundreds of eV at plasma edges to 10 keV at the center of the plasma, where most of the impurity ions are nearly fully ionized. These highly stripped ions interact strongly with electrons in the plasma, leading to further excitation and ionization of the ions, as well as electron capture. Radiations are emitted during these processes, which easily escape to plasma container walls, thus cooling the plasma. One of the dominant modes of radiation emission has been identified with dielectronic recombination. This paper reviews this work

International conference on individual monitoring of ionising radiation

International Nuclear Information System (INIS)

Vanhavere, Filip

2016-01-01

This special issue of the journal Radiation Protection Dosimetry is dedicated to the Proceedings of the International Conference on Individual Monitoring of Ionising Radiation (IM2015), which is the fifth of a series of conferences dealing with individual monitoring. This conference series is initiated by EURADOS, the European Radiation Dosimetry Group, and is organised every 5 years. In 2015, the conference was jointly organised by the Belgian Nuclear Research Centre (SCK.CEN), AV Controlatom, and the Vrije Universiteit Brussel. It brought together scientists from regulatory authorities, individual monitoring services (IMS), research bodies, European networks and companies, for the purpose of facilitating the dissemination of knowledge, exchanging experiences and promoting new ideas in the field of individual monitoring. After the conference, 124 papers were submitted for publication in these peer-reviewed proceedings. From these, 103 were finally accepted for publication. The help of the numerous referees and the guest editors is very much appreciated. These proceedings provide a full image of the IM2015 conference. The high-level publications will be useful to improve the state of individual monitoring all over the world and aim to inspire many scientists to continue their work on a better monitoring of radiologically exposed workers

Highly Durable Platinum Single-Atom Alloy Catalyst for Electrochemical Reactions

DEFF Research Database (Denmark)

Kim, Jiwhan; Roh, Chi-Woo; Sahoo, Suman Kalyan

2018-01-01

Single atomic Pt catalyst can offer efficient utilization of the expensive platinum and provide unique selectivity because it lacks ensemble sites. However, designing such a catalyst with high Pt loading and good durability is very challenging. Here, single atomic Pt catalyst supported on antimony...... functional theory calculations show that replacing Sb sites with Pt atoms in the bulk phase or at the surface of SbSn or ATO is energetically favorable. The Pt1/ATO shows superior activity and durability for formic acid oxidation reaction, compared to a commercial Pt/C catalyst. The single atomic Pt...... structure is retained even after a harsh durability test, which is performed by repeating cyclic voltammetry in the range of 0.05–1.4 V for 1800 cycles. A full cell is fabricated for direct formic acid fuel cell using the Pt1/ATO as an anode catalyst, and an order of magnitude higher cell power is obtained...

Nuclear and cytoplasmic signalling in the cellular response to ionising radiation

International Nuclear Information System (INIS)

Szumiel, Irena

2001-01-01

DNA is the universal primary target for ionising radiation; however, the cellular response is highly diversified not only by differential DNA repair ability. The monitoring system for the ionising radiation-inflicted DNA damage consists of 3 apparently independently acting enzymes which are activated by DNA breaks: two protein kinases, ATM (ataxia telangiectasia mutated) and DNA-PK (DNA-dependent protein kinase) and a poly(ADP-ribose) polymerase, PARP-1. These 3 enzymes are the source of alarm signals, which affect to various extents DNA repair, progression through the cell cycle and eventually the pathway to cell death. Their functions probably are partly overlapping. On the side of DNA repair their role consists in recruiting and/or activating the repair enzymes, as well as preventing illegitimate recombination of the damaged sites. A large part of the nuclear signalling pathway, including the integrating role of TP53 has been revealed. Two main signalling pathways start at the plasma membrane: the MAPK/ERK (mitogen and extracellular signal regulated protein kinase family) 'survival pathway' and the SAPK/JNK (stress-activated protein kinase/c-Jun N-terminal kinase) 'cell death pathway'. The balance between them is likely to determine the cell's fate. An additional important 'survival pathway' starts at the insulin-like growth factor type I receptor (IGF-IR), involves phosphoinositide- 3 kinase and Akt kinase and is targeted at inactivation of the pro-apoptotic BAD protein. Interestingly, over-expression of IGF-IR almost entirely abrogates the extreme radiation sensitivity of ataxia telangiectasia cells. When DNA break rejoining is impaired, the cell is unconditionally radiation sensitive. The fate of a repair-competent cell is determined by the time factor: the cell cycle arrest should be long enough to ensure the completion of repair. Incomplete repair or misrepair may be tolerated, when generation of the death signal is prevented. So, the character and timing

Proceedings of the workshop on opportunities for atomic physics using slow, highly-charged ions

International Nuclear Information System (INIS)

1987-01-01

The study of atomic physics with highly-charged ions is an area of intense activity at the present time because of a convergence of theoretical interest and advances in experimental techniques. The purpose of the Argonne ''Workshop on Opportunities for Atomic Physics Using Slow, Highly-Charged Ions'' was to bring together atomic, nuclear, and accelerator physicists in order to identify what new facilities would be most useful for the atomic physics community. The program included discussion of existing once-through machines, advanced ion sources, recoil ion techniques, ion traps, and cooler rings. One of the topics of the Workshop was to discuss possible improvement to the ANL Tandem-Linac facility (ATLAS) to enhance the capability for slowing down ions after they are stripped to a high-charge state (the Accel/Decel technique). Another topic was the opportunity for atomic physics provided by the ECR ion source which is being built for the Uranium Upgrade of ATLAS. 18 analytics were prepared for the individual papers in this volume

Bioaerosol detection by aerosol TOF-mass spectrometry: Application of matrix assisted laser desorption/ionisation

NARCIS (Netherlands)

Wuijckhuijse, A.L. van; Stowers, M.A.; Kientz, Ch.E.; Marijnissen, J.C.M.; Scarlett, B.

2000-01-01

In previous publications the use of an aerosol time of flight mass spectrometer was reported for the on-line measurements of aerosols (Weiss 1997, Kievit 1995). The apparatus is capable of measuring the size as well as the chemical composition, by the use of Laser Desorption/Ionisation (LDI), of an

Atomic beam formed by the vaporization of a high velocity pellet

International Nuclear Information System (INIS)

Foster, C.A.; Hendricks, C.D.

1974-01-01

A description of an atomic beam formed by vaporizing an electrostatically accelerated high velocity pellet is given. Uniformly sized droplets of neon will be formed by the mechanical disintegration of liquid jet and frozen by adiabatic vaporization in vacuum. The pellets produced will be charged and accelerated by contacting a needle held at high potential. The accelerated pellets will be vaporized forming a pulse of mono-energetic atoms. The advantages are that a wide range of energies will be possible. The beam will be mono-energetic. The beam is inheretly pulsed, allowing a detailed time of flight velocity distribution measurement. The beam will have a high instantaneous intensity. The beam will be able to operate into an ultra high vacuum chamber

Saturation effects in the ionisation of He by H/sup +/ and He/sup 2+/ impact at intermediate energies

Energy Technology Data Exchange (ETDEWEB)

Bernardi, G.C.; Garibotti, C.R.; Suarez, S.; Fainstein, P.D.

1989-01-01

Projectile charge dependence of double differential ionisation cross section for H/sup +/ and He/sub 3//sup 2+/ on He is studied both theoretically and experimentally. The experimental ratio R of the emission induced by 50 and 100 KeV/u He/sub 3//sup 2+/ and H/sup +/ is compared with calculations from the CDW-EIS model. We report two main effects: (a) a decrease of R with increasing angle of electronic emission, (b) a sudden enhancement of R in the high energy side of the ECC peak.

Recent developments at the atomic and molecular data unit of the International Atomic Energy Agency

International Nuclear Information System (INIS)

Clark, R.E.H.; )

2002-01-01

The Atomic and Molecular (A+M) Data Unit of the IAEA main purpose is to establish and maintain databases in support of nuclear fusion energy research. This encompasses a very large number of processes in atomic, molecular, and plasma - material interaction physics. Recent improvements and additions to these databases are presented. A prototype search engine, which searches five different sites for radiative data and two sites for electron impact excitation and ionization data is introduced. It is available at the IAEA, Weizmann Institute and GAPHYOR web sites. Data on erosion materials produced by the Co-ordinated research project (CRP) 'Plasma-interaction induced erosion of fusion reactor materials' was evaluated, fitted to physically realistic forms for angle and energy dependence and the resulting fits were added to the online electronic database. In a CRP on radiative power losses in plasmas, many lenghtly modelling calculations were carried out. In addition to providing the calculated radiated power, effective ionisation and recombination rate coefficients were derived. These data were stored along with the populations of the ion stages as well as the total radiation from each ion stage. Thus, it is possible to use these data to interpolate in temperature and electron density to obtain the radiated power at an arbitrary temperature and density. A preliminary version of a new interface to the bibliographic database at the A+M Data unit was developed, it allows the user to search by author and/or keyword. The resulting references are displayed along with a link to the home page of the journal where possible. A code for calculation electron impact excitation cross sections using the so-called 'average approximation' and a version of the Hartree-Fock atomic structure code were installed in the unit and can be run through an interface at the web page. (nevyjel)

Adaptive response to ionising radiation induced by cadmium in zebrafish embryos

International Nuclear Information System (INIS)

Choi, V W Y; Ng, C Y P; Kong, M K Y; Yu, K N; Cheng, S H

2013-01-01

An adaptive response is a biological response where the exposure of cells or animals to a low priming exposure induces mechanisms that protect the cells or animals against the detrimental effects of a subsequent larger challenging exposure. In realistic environmental situations, living organisms can be exposed to a mixture of stressors, and the resultant effects due to such exposures are referred to as multiple stressor effects. In the present work we demonstrated, via quantification of apoptosis in the embryos, that embryos of the zebrafish (Danio rerio) subjected to a priming exposure provided by one environmental stressor (cadmium in micromolar concentrations) could undergo an adaptive response against a subsequent challenging exposure provided by another environmental stressor (alpha particles). We concluded that zebrafish embryos treated with 1 to 10 μM Cd at 5 h postfertilisation (hpf) for both 1 and 5 h could undergo an adaptive response against subsequent ∼4.4 mGy alpha-particle irradiation at 10 hpf, which could be interpreted as an antagonistic multiple stressor effect between Cd and ionising radiation. The zebrafish has become a popular vertebrate model for studying the in vivo response to ionising radiation. As such, our results suggested that multiple stressor effects should be carefully considered for human radiation risk assessment since the risk may be perturbed by another environmental stressor such as a heavy metal. (paper)

Ionising radiations - an ecological problem of indoor architectural environment

International Nuclear Information System (INIS)

Djukanovic, M.

1995-01-01

Architectural buildings are assessed not only for their esthetic characteristics but human settlements are considered now, as ecosystems and homes and flats as habitats (bio tops). Because of that healthy environment and influences of nonpolluting factors are of a great importance. The use of appropriate building materials harmless to health, contrary to the use of those that emit radon with its ionising effects and consequent health hazards, is of a great importance, too. The purpose of this paper is to emphasize the importance of investigation of building materials before their use, as well as the importance of quality control of soil where the construction is planned. (author)

On analytical fits for electron impact ionisation cross sections

International Nuclear Information System (INIS)

Godunov, A.L.; Ivanov, P.B.

1999-01-01

The problem of providing accurate recommended analytical fits for electron impact ionisation cross sections is discussed, and a number of approaches are considered on the sample case of neon and its ions. The previously known fits are being reassessed using complete experimental and theoretical data, with the preference for experiment, to avoid systematic shifts introduced by the present calculation methods. The feasibility of the standard BELI formula is investigated in detail, and a number of other analytical expressions is suggested, approximating single-ionization cross sections in the whole range of energies. The factors influencing the accuracy of the fits and the physical meaning of the parameters obtained are discussed. (orig.)

Atomic processes in high-density plasmas

International Nuclear Information System (INIS)

More, R.M.

1982-01-01

This review covers dense atomic plasmas such as that produced in inertial confinement fusion. The target implosion physics along with the associated atomic physics, i.e., free electron collision phenomena, electron states I, electron states II, and nonequilibrium plasma states are described

Acceleration of multiply charged ions by a high-contrast femtosecond laser pulse of relativistic intensity from the front surface of a solid target

Czech Academy of Sciences Publication Activity Database

Shulyapov, S. A.; Mordvintsev, I. M.; Ivanov, K. A.; Volkov, P. V.; Zarubin, P. I.; Ambrožová, Iva; Turek, Karel; Savelyev, A. B.

2016-01-01

Roč. 46, č. 5 (2016), s. 432-436 ISSN 1063-7818 Institutional support: RVO:61389005 Keywords : relativistic intensity * contrast * laser plasma * ion acceleration * multiply charged ions * collision ionisation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.119, year: 2016

The development of high-resolution spectroscopic methods and their use in atomic structure studies

International Nuclear Information System (INIS)

Poulsen, O.

1984-01-01

This thesis discusses work performed during the last nine years in the field of atomic spectroscopy. Several high-resolution techniques, ranging from quantum beats, level crossings, rf-laser double resonances to nonlinear field atom interactions, have been employed. In particular, these methods have been adopted and developed to deal with fast accelerated atomic or ionic beams, allowing studies of problems in atomic-structure theory. Fine- and hyperfine-structure determinations in the He I and Li I isoelectronic sequences, in 51 V I, and in 235 U I, II have permitted a detailed comparison with ab initio calculations, demonstrating the change in problems when going towards heavier elements or higher ionization stage. The last part of the thesis is concerned with the fundamental question of obtaining very high optical resolution in the interaction between a fast accelerated atom or ion beam and a laser field, this problem being the core in the continuing development of atomic spectroscopy necessary to challenge the more precise and sophisticated theories advanced. (Auth.)

The potential of organic (electrospray- and atmospheric pressure chemical ionisation) mass spectrometric techniques coupled to liquid-phase separation for speciation analysis.

Science.gov (United States)

Rosenberg, Erwin

2003-06-06

The use of mass spectrometry based on atmospheric pressure ionisation techniques (atmospheric pressure chemical ionisation, APCI, and electrospray ionisation, ESI) for speciation analysis is reviewed with emphasis on the literature published in and after 1999. This report accounts for the increasing interest that atmospheric pressure ionisation techniques, and in particular ESI, have found in the past years for qualitative and quantitative speciation analysis. In contrast to element-selective detectors, organic mass spectrometric techniques provide information on the intact metal species which can be used for the identification of unknown species (particularly with MS-MS detection) or the confirmation of the actual presence of species in a given sample. Due to the complexity of real samples, it is inevitable in all but the simplest cases to couple atmospheric pressure MS detection to a separation technique. Separation in the liquid phase (capillary electrophoresis or liquid chromatography in reversed phase, ion chromatographic or size-exclusion mode) is particularly suitable since the available techniques cover a very wide range of analyte polarities and molecular mass. Moreover, derivatisation can normally be avoided in liquid-phase separation. Particularly in complex environmental or biological samples, separation in one dimension is not sufficient for obtaining adequate resolution for all relevant species. In this case, multi-dimensional separation, based on orthogonal separation techniques, has proven successful. ESI-MS is also often used in parallel with inductively coupled plasma MS detection. This review is structured in two parts. In the first, the fundamentals of atmospheric pressure ionisation techniques are briefly reviewed. The second part of the review discusses recent applications including redox species, use of ESI-MS for structural elucidation of metal complexes, characterisation and quantification of small organometallic species with relevance to

Protection of the environment from ionising radiation. The development and application of a system of radiation protection for the environment. Proceedings of the third international symposium on the protection of the environment from ionising radiation (SPEIR 3). Unedited papers

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-05-01

In recent years, awareness of the vulnerability of the environment has increased, as evidenced by new and developing international policies for environmental protection, starting with the Rio Declaration of 1992. In the context of ionizing radiation, the existing international approach is largely based on providing for the protection of humans, but this is being critically reviewed in several international fora. It is in this context that the Third International Symposium on Protection of the Environment from Ionising Radiation (SPEIR 3) was held between 22 and 26 July 2002, in Darwin, Australia. The symposium focused on issues related to the development and application of a system of radiation protection for the environment. The symposium programme included sessions dedicated to: ongoing research on the effects, responses and mechanisms of the interactions of ionizing radiation with biota; policy and ethical dimensions of the development of a framework for environmental radiation protection; and the development and use of methods and models for evaluating radiation as a stressor to the environment. Three workshops were held to allow for detailed discussion of each of these subjects. This symposium was the third in a series. The first International Symposium on Ionising Radiation: Protection of the Natural Environment, was held in Stockholm, Sweden, 20-24 May 1996. This symposium was organized jointly by the Swedish Radiation Protection Institute (SSI) and the Atomic Energy Control Board (AECB) of Canada, and the proceedings were published by the Akademitryck AB, Edsbruk, Sweden in 1996. The second International Symposium on Ionizing Radiation: Environmental Protection Approaches for Nuclear Facilities, was held in Ottawa, Canada, 10-14 May 1999, and was organized by the Canadian Nuclear Safety Commission (CNSC), the Supervising Scientists Group of Environment Australia, and the Swedish Radiation Protection Institute (SSI). The proceedings were published in April

Protection of the environment from ionising radiation. The development and application of a system of radiation protection for the environment. Proceedings of the third international symposium on the protection of the environment from ionising radiation (SPEIR 3). Unedited papers

International Nuclear Information System (INIS)

2003-01-01

In recent years, awareness of the vulnerability of the environment has increased, as evidenced by new and developing international policies for environmental protection, starting with the Rio Declaration of 1992. In the context of ionizing radiation, the existing international approach is largely based on providing for the protection of humans, but this is being critically reviewed in several international fora. It is in this context that the Third International Symposium on Protection of the Environment from Ionising Radiation (SPEIR 3) was held between 22 and 26 July 2002, in Darwin, Australia. The symposium focused on issues related to the development and application of a system of radiation protection for the environment. The symposium programme included sessions dedicated to: ongoing research on the effects, responses and mechanisms of the interactions of ionizing radiation with biota; policy and ethical dimensions of the development of a framework for environmental radiation protection; and the development and use of methods and models for evaluating radiation as a stressor to the environment. Three workshops were held to allow for detailed discussion of each of these subjects. This symposium was the third in a series. The first International Symposium on Ionising Radiation: Protection of the Natural Environment, was held in Stockholm, Sweden, 20-24 May 1996. This symposium was organized jointly by the Swedish Radiation Protection Institute (SSI) and the Atomic Energy Control Board (AECB) of Canada, and the proceedings were published by the Akademitryck AB, Edsbruk, Sweden in 1996. The second International Symposium on Ionizing Radiation: Environmental Protection Approaches for Nuclear Facilities, was held in Ottawa, Canada, 10-14 May 1999, and was organized by the Canadian Nuclear Safety Commission (CNSC), the Supervising Scientists Group of Environment Australia, and the Swedish Radiation Protection Institute (SSI). The proceedings were published in April

Time-dependent hydrogen ionisation in 3D simulations of the solar chromosphere. Methods and first results

NARCIS (Netherlands)

Leenaarts, J.; Wedemeyer-Bohm, S.

2006-01-01

Context. The hydrogen ionisation degree deviates substantially from statistical equilibrium under the conditions of the solar chromosphere. A realistic description of this atmospheric layer thus must account for time-dependent non-equilibrium effects. Aims. Advancing the realism of numerical

Highly n -doped graphene generated through intercalated terbium atoms

Science.gov (United States)

Daukiya, L.; Nair, M. N.; Hajjar-Garreau, S.; Vonau, F.; Aubel, D.; Bubendorff, J. L.; Cranney, M.; Denys, E.; Florentin, A.; Reiter, G.; Simon, L.

2018-01-01

We obtained highly n -type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in ultrahigh vacuum. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 1015cm-2 . In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and the monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n -doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and x-ray photoelectron spectroscopy measurements. The band structure of this highly n -doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac cone), which has been associated with an electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals.

Reactions of the ionized enol tautomer of acetanilide: elimination of HNCO via a novel rearrangement.

Science.gov (United States)

Heydorn, Lisa N; Carter, Lynn M; Bowen, Richard D; Terlouw, Johan K

2003-01-01

The reactions of ionised acetanilide, C(6)H(5)NH(=O)CH(3)(.+), and its enol, C(6)H(5)NH(OH)=CH(2)(.+), have been studied by a combination of tandem mass spectrometric and computational methods. These two isomeric radical cations have distinct chemistries at low internal energies. The keto tautomer eliminates exclusively CH(2)=C=O to give ionised aniline. In contrast, the enol tautomer loses H-N=C=O, via an unusual skeletal rearrangement, to form predominantly ionised methylene cyclohexadiene. Hydrogen atom loss also occurs from the enol tautomer, with the formation of protonated oxindole. The mechanisms for H-N=C=O and hydrogen atom loss both involve cyclisation; the former proceeds via a spiro transition state formed by attachment of the methylene group to the ipso position, whereas the latter entails the formation of a five-membered ring by attachment to the ortho position. The behaviour of labelled analogues reveals that these two processes have different site selectivities. Hydrogen atom loss involves a reverse critical energy and is subject to an isotope effect. Surprisingly, attempts to promote the enolisation of ionised acetanilide by proton-transport catalysis were unsuccessful. In a reversal of the usual situation for ionised carbonyl compounds, ionised acetanilide is actually more stable than its enol tautomer. The enol tautomer was resistant to proton-transport catalysed ketonisation to ionised acetanilide, possibly because the favoured geometry of the encounter complex with the base molecule is inappropriate for facilitating tautomerisation.

High-spin excitations of atomic nuclei

International Nuclear Information System (INIS)

Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing

2004-01-01

The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)

High-resolution measurements of x rays from ion-atom collisions

International Nuclear Information System (INIS)

Knudson, A.R.

1974-01-01

High resolution measurements of K x-ray spectra produced by ion-atom collisions at MeV energies are presented. These measurements indicate that a distribution of L-shell vacancies accompanies K-shell excitation. The variation of these spectra as a function of incident ion energy and atomic number is discussed. Difficulties in the analysis of these spectra due to rearrangement of vacancies between the time of the collision and the time of x-ray emission are considered. The use of high resolution x-ray measurements to obtain information on projectile ion vacancy configurations is demonstrated by data for Ar ions in KCl. X-ray spectra from Al projectiles in a variety of targets were measured and the effect of target composition on these spectra is discussed

Proceedings of the workshop on opportunities for atomic physics using slow, highly-charged ions

Energy Technology Data Exchange (ETDEWEB)

1987-01-01

The study of atomic physics with highly-charged ions is an area of intense activity at the present time because of a convergence of theoretical interest and advances in experimental techniques. The purpose of the Argonne ''Workshop on Opportunities for Atomic Physics Using Slow, Highly-Charged Ions'' was to bring together atomic, nuclear, and accelerator physicists in order to identify what new facilities would be most useful for the atomic physics community. The program included discussion of existing once-through machines, advanced ion sources, recoil ion techniques, ion traps, and cooler rings. One of the topics of the Workshop was to discuss possible improvement to the ANL Tandem-Linac facility (ATLAS) to enhance the capability for slowing down ions after they are stripped to a high-charge state (the Accel/Decel technique). Another topic was the opportunity for atomic physics provided by the ECR ion source which is being built for the Uranium Upgrade of ATLAS. 18 analytics were prepared for the individual papers in this volume.

Significance of grafting in radiation curing reactions. Comparison of ionising radiation and UV systems

International Nuclear Information System (INIS)

Zilic, E.; Ng, L.; Viengkhou, V.; Garnett, J.L.

1998-01-01

Full text: Radiation curing is now an accepted commercial technology where both ionising radiation (electron beam) and ultra violet light (UV) sources are used. Grafting is essentially the copolymerisation of a monomer/oligomer to a backbone polymer whereas curing is the rapid polymerisation of a monomer/oligomer mixture onto the surface of the substrate. There is no time scale theoretically associated with grafting processes which can occur in minutes or hours whereas curing reactions are usually very rapid, occurring within a fraction of a second. An important difference between grafting and curing is the nature of the bonding occurring in each process. In grafting covalent carbon-carbon bonds are formed, whereas in curing, bonding usually involves weaker Van der Waals or London dispersion forces. The bonding properties of the systems are important in determining their use commercially. Thus the possibility that concurrent grafting during curing could occur in a system is important since if present, grafting would not only minimise delamination of the coated product but could also, in some circumstances, render difficulties recycling of the finished product especially if it were cellulosic. Hence the conditions for observing the occurrence of concurrent grafting during radiation curing are important. In the present paper, this problem has been studied by examining the effect that the components used in radiation curing exert on a typical reaction. Instead of electron beam sources, the spent fuel element facility at Lucas Heights is used to simulate such ionising radiation sources. The model system utilised is the grafting of a typical methacrylate to cellulose. This is the generic chemistry used in curing systems. The effect of typical additives from curing systems including polyfunctional monomer and oligomers in the grafting reactions have been studied. The ionising radiation results have been compared with analogous data from UV experiments. The significance

An isotope view on ionising radiation as a source of sulphuric acid

DEFF Research Database (Denmark)

Enghoff, Martin Andreas Bødker; Bork, Nicolai Christian; Hattori, S.

2012-01-01

Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism has remained undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a miss...... yields of the experiments, suggests a mechanism in which ionising radiation may lead to hydrated ion clusters that serve as nanoreactors for S(IV) to S(VI) conversion....

An isotopic analysis of ionising radiation as a source of sulphuric acid

DEFF Research Database (Denmark)

Enghoff, Martin Andreas Bødker; Bork, Nicolai Christian; Hattori, S.

2012-01-01

Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism has remained undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a miss...... of the experiments, suggests a mechanism in which ionising radiation may lead to hydrated ion clusters that serve as nanoreactors for S(IV) to S(VI) conversion....

Atomic layer deposition for high-efficiency crystalline silicon solar cells

NARCIS (Netherlands)

Macco, B.; van de Loo, B.W.H.; Kessels, W.M.M.; Bachmann, J.

2017-01-01

This chapter illustrates that Atomic Layer Deposition (ALD) is in fact an enabler of novel high-efficiency Si solar cells, owing to its merits such as a high material quality, precise thickness control, and the ability to prepare film stacks in a well-controlled way. It gives an overview of the

High incidence of meningioma among Hiroshima atomic bomb survivors

International Nuclear Information System (INIS)

Shintani, Takahiro; Hayakawa, Norihiko; Hoshi, Masaharu

1999-01-01

Since the atomic bomb explosions in Hiroshima and Nagasaki, high incidences of leukemia, thyroid cancer and other tumors have been reported as atomic bomb-induced tumors. We investigated the incidence of meningioma among Hiroshima atomic bomb survivors. Sixty-eight patients surgically treated for meningioma who had been within 2.0 km of the hypocenter of the explosion were identified. Six hundred and seven non-exposed patients with meningioma were also studied. Treatment dates were from 1975 to 1992. The incidences of meningioma among 68 subjects within 2.0 km and 607 non-exposed patients were 8.7 and 3.0 cases per 10 5 persons per year, respectively. The incidences of meningioma among the survivors of Hiroshima in 5-year intervals since 1975 were 5.3, 7.4, 10.1, and 14.9, respectively. The incidences of meningioma classified by distances from the hypocenter of 1.5-2.0 km, 1.0-1.5 km and less than 1.0 km were 6.3, 7.6 and 20.0, respectively. The incidences of meningioma classified by doses to the brain of 0-0.099 Sv, 0.1-0.99 Sv and more than 1.0 Sv were 7.7, 9.2 and 18.2, respectively. The incidence of meningioma among Hiroshima atomic bomb survivors has increased since 1975. There was a significant correlation between the incidence and the dose of radiation to the brain. The present findings strongly suggest that meningioma is one of the tumors induced by atomic bombing in Hiroshima. (author)

Investigation of the impact of high liquid viscosity on jet atomization in crossflow via high-fidelity simulations

Science.gov (United States)

Li, Xiaoyi; Gao, Hui; Soteriou, Marios C.

2017-08-01

Atomization of extremely high viscosity liquid can be of interest for many applications in aerospace, automotive, pharmaceutical, and food industries. While detailed atomization measurements usually face grand challenges, high-fidelity numerical simulations offer the advantage to comprehensively explore the atomization details. In this work, a previously validated high-fidelity first-principle simulation code HiMIST is utilized to simulate high-viscosity liquid jet atomization in crossflow. The code is used to perform a parametric study of the atomization process in a wide range of Ohnesorge numbers (Oh = 0.004-2) and Weber numbers (We = 10-160). Direct comparisons between the present study and previously published low-viscosity jet in crossflow results are performed. The effects of viscous damping and slowing on jet penetration, liquid surface instabilities, ligament formation/breakup, and subsequent droplet formation are investigated. Complex variations in near-field and far-field jet penetrations with increasing Oh at different We are observed and linked with the underlying jet deformation and breakup physics. Transition in breakup regimes and increase in droplet size with increasing Oh are observed, mostly consistent with the literature reports. The detailed simulations elucidate a distinctive edge-ligament-breakup dominated process with long surviving ligaments for the higher Oh cases, as opposed to a two-stage edge-stripping/column-fracture process for the lower Oh counterparts. The trend of decreasing column deflection with increasing We is reversed as Oh increases. A predominantly unimodal droplet size distribution is predicted at higher Oh, in contrast to the bimodal distribution at lower Oh. It has been found that both Rayleigh-Taylor and Kelvin-Helmholtz linear stability theories cannot be easily applied to interpret the distinct edge breakup process and further study of the underlying physics is needed.

Ionisation of atoms, molecules and biomolecules by impact of multiply charged ions of high energy: classical and quantal comparison

International Nuclear Information System (INIS)

Abbas, I.

2008-05-01

We have developed a relatively simple model to calculate total cross-sections of various ionizing processes involving ion-atom or ion-molecule collisions. This model is based on the Zarour and Saalmann model and has benefited from 2 other models: the classical over-barrier (COB) model and the classical trajectory Monte-Carlo (CTMC) model. The COB model is used to describe the initial conditions of the target's electrons and their process us of creation while the CTMC model is used to build the statistical aspects necessary to calculate the cross sections of the ionizing processes. 3 major improvements have been brought to the Zarour and Saalmann model. First, the particle-particle interactions have been described by a Coulombian potential which is more realistic. Secondly, the initial conditions in the target are better represented by taking into account in an aleatory manner the position and speed distributions of the electrons. Thirdly, the use of energy criteria instead of purely geometrical ones to describe the final situation of the electrons has led to a better determination of the possible ionizing events. We have validated our model by applying it first, in collisional systems involving multi-charged projectiles like H + , He 2+ , Li 3+ , C 6+ , O 8+ and Ne 10+ and simple targets like H, He and H 2 , for which a lot of experimental data is available. Then, we have studied collisions involving the water molecule for which experimental and experimental data exist. Satisfactorily results for H 2 O target has led us to study other biological targets like adenine or cytosine. We have shown that our results are valid for impact energies over 100 keV/uma and most satisfactorily results concern simple ionizing processes like simple capture and simple ionization. For more complex processes such as transfer-ionization, double capture or double ionization, our results are valid for helium and hydrogen targets. In the case of water, the cross-sections of double

HIAF: New opportunities for atomic physics with highly charged heavy ions

Science.gov (United States)

Ma, X.; Wen, W. Q.; Zhang, S. F.; Yu, D. Y.; Cheng, R.; Yang, J.; Huang, Z. K.; Wang, H. B.; Zhu, X. L.; Cai, X.; Zhao, Y. T.; Mao, L. J.; Yang, J. C.; Zhou, X. H.; Xu, H. S.; Yuan, Y. J.; Xia, J. W.; Zhao, H. W.; Xiao, G. Q.; Zhan, W. L.

2017-10-01

A new project, High Intensity heavy ion Accelerator Facility (HIAF), is currently being under design and construction in China. HIAF will provide beams of stable and unstable heavy ions with high energies, high intensities and high quality. An overview of new opportunities for atomic physics using highly charged ions and radioactive heavy ions at HIAF is given.

Characterisation of exposure to non-ionising electromagnetic fields in the Spanish INMA birth cohort: Study protocol

NARCIS (Netherlands)

M. Gallastegi (Mara); M. Guxens Junyent (Mònica); A. Jiménez-Zabala (Ana); I. Calvente (Irene); M. Fernández (Marta); L. Birks (Laura); B. Struchen (Benjamin); M. Vrijheid (Martine); M. Estarlich (Marisa); M.F. Fernandez (Mariana); M. Torrent (Maties); F. Ballester (Ferran); J.J. Aurrekoetxea (Juan José); J. Ibarluzea (Jesús); D. Guerra (David); J. González (Julián); M. Röösli (Martin); L. Santa-Marina (Loreto)

2016-01-01

textabstractBackground: Analysis of the association between exposure to electromagnetic fields of non-ionising radiation (EMF-NIR) and health in children and adolescents is hindered by the limited availability of data, mainly due to the difficulties on the exposure assessment. This study protocol

Controllable isotope fractionation with thermal ionisation mass-spectrometers

International Nuclear Information System (INIS)

Hebeda, E.H.

1980-01-01

Isotopic ratios measured with thermal ionisation mass-spectrometers are biased by fractionation effects. A sample must therefore be analyzed according to the same procedures as applied for the analysis of the standard reference material. A comparison of the behaviour of the sample with that of the standard can then be used as a criterion whether the analytical results are acceptable or not. In this way it is possible to obtain reproducibilities similar to those for elements acceptable or not. In this way it is possible to obtain reproducibilities similar to those for elements where the fractionation can be determined by an internal standard. This procedure of controlled fractionation is demonstrated by means of the 88 Sr/ 86 Sr ratios measured on geological samples and the SRM 987 standard. (orig.)

On the Zeeman Effect in highly excited atoms: 2. Three-dimensional case

International Nuclear Information System (INIS)

Baseia, B.; Medeiros e Silva Filho, J.

1984-01-01

A previous result, found in two-dimensional hydrogen-atoms, is extended to the three-dimensional case. A mapping of a four-dimensional space R 4 onto R 3 , that establishes an equivalence between Coulomb and harmonic potentials, is used to show that the exact solution of the Zeeman effect in highly excited atoms, cannot be reached. (Author) [pt

Airborne hydrogen cyanide measurements using a chemical ionisation mass spectrometer for the plume identification of biomass burning forest fires

Directory of Open Access Journals (Sweden)

M. Le Breton

2013-09-01

Full Text Available A chemical ionisation mass spectrometer (CIMS was developed for measuring hydrogen cyanide (HCN from biomass burning events in Canada using I− reagent ions on board the FAAM BAe-146 research aircraft during the BORTAS campaign in 2011. The ionisation scheme enabled highly sensitive measurements at 1 Hz frequency through biomass burning plumes in the troposphere. A strong correlation between the HCN, carbon monoxide (CO and acetonitrile (CH3CN was observed, indicating the potential of HCN as a biomass burning (BB marker. A plume was defined as being 6 standard deviations above background for the flights. This method was compared with a number of alternative plume-defining techniques employing CO and CH3CN measurements. The 6-sigma technique produced the highest R2 values for correlations with CO. A normalised excess mixing ratio (NEMR of 3.68 ± 0.149 pptv ppbv−1 was calculated, which is within the range quoted in previous research (Hornbrook et al., 2011. The global tropospheric model STOCHEM-CRI incorporated both the observed ratio and extreme ratios derived from other studies to generate global emission totals of HCN via biomass burning. Using the ratio derived from this work, the emission total for HCN from BB was 0.92 Tg (N yr−1.

High sensitivity detection of selenium by laser excited atomic fluorescence spectrometry using electrothermal atomization

International Nuclear Information System (INIS)

Heitmann, U.; Hese, A.; Schoknecht, G.; Gries, W.

1995-01-01

The high sensitivity detection of the trace element selenium is reported. The analytical method applied is Laser Excited Atomic Fluorescence Spectrometry using Electrothermal Atomization within a graphite furnace atomizer. For the production of tunable laser radiation in the VUV spectral region a laser system was developed which consists of two dye lasers pumped by a Nd:YAG laser. The laser radiations are subsequently frequency doubled and sum frequency mixed by nonlinear optical KDP or BBO crystals, respectively. The system works with a repetition rate of 20 Hz and provides output energies of up to 100 μJ in the VUV at a pulse duration of 5 ns. The analytical investigations were focused on the detection of selenium in aqueous solutions and samples of human whole blood. From measurements on aqueous standards detection limits of 1.5 ng/l for selenium were obtained, with corresponding absolute detected masses of only 15 fg. The linear dynamic range spanned six orders of magnitude and good precision was achieved. In case of human whole blood samples the recovery was found to be within the range of 96% to 104%. The determination of the selenium content yielded medians of [119.5 ± 17.3] μg/l for 200 frozen blood samples taken in 1988 and [109.1 ± 15.6] μg/l for 103 fresh blood samples. (author)

Protection of the environment from ionising radiation: ethical issues

International Nuclear Information System (INIS)

Oughton, D.

2002-01-01

The paper identifies some of the main ethical issues concerning the protection of the environment from radiation and suggests ways in which ethics can aid in developing a system of protection. After a presentation of background on ethical theory and environmental ethics, three main issues related to practical environmental protection are discussed: First, the question of who or what has moral standing; second the appropriate level of protection; and third compatibility with other environmental stressors. In summary, the paper argues that there are strong ethical grounds for efforts to provide for the protection of the environment and that, all other things being equal, there is no reason to treat ionising radiation differently to other environmental stressors. (author)

Containerless high temperature property measurements by atomic fluorescence

Science.gov (United States)

Schiffman, R. A.; Walker, C. A.

1984-01-01

Laser induced fluorescence (LIF) techniques for containerless study of high temperature processes and material properties was studied. Gas jet and electromagnetic levitation and electromagnetic and laser heating techniques are used with LIF in earth-based containerless high temperature experiments. Included are the development of an apparatus and its use in the studies of (1) chemical reactions on Al2O3, molybdenum, tungsten and LaB6 specimens, (2) methods for noncontact specimen temperature measurement, (3) levitation jet properties and (4) radiative lifetime and collisional energy transfer rates for electronically excited atoms.

High-speed atomic force microscopy coming of age

International Nuclear Information System (INIS)

Ando, Toshio

2012-01-01

High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed. (topical review)

High-speed atomic force microscopy coming of age

Science.gov (United States)

Ando, Toshio

2012-02-01

High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed.

Towards weighing individual atoms by high-angle scattering of electrons

Energy Technology Data Exchange (ETDEWEB)

Argentero, G.; Mangler, C.; Kotakoski, J.; Eder, F.R.; Meyer, J.C., E-mail: Jannik.Meyer@univie.ac.at

2015-04-15

We consider theoretically the energy loss of electrons scattered to high angles when assuming that the primary beam can be limited to a single atom. We discuss the possibility of identifying the isotopes of light elements and of extracting information about phonons in this signal. The energy loss is related to the mass of the much heavier nucleus, and is spread out due to atomic vibrations. Importantly, while the width of the broadening is much larger than the energy separation of isotopes, only the shift in the peak positions must be detected if the beam is limited to a single atom. We conclude that the experimental case will be challenging but is not excluded by the physical principles as far as considered here. Moreover, the initial experiments demonstrate that the separation of gold and carbon based on a signal that is related to their mass, rather than their atomic number. - Highlights: • We explore how energy loss spectroscopy could be used to obtain information about the mass, rather than the charge, of atoms. • The dose and precision that would be needed to distinguish between the two isotopes of carbon, C12 and C13, is estimated. • Signal broadening due to phonons is included in the calculation. • Initial experiments show the separation between gold and carbon based on their mass rather than charge.

V. S. Lebedev and I. L. Beigman, Physics of Highly Excited Atoms and Ions

Science.gov (United States)

Mewe, R.

1999-07-01

This book contains a comprehensive description of the basic principles of the theoretical spectroscopy and experimental spectroscopic diagnostics of Rydberg atoms and ions, i.e., atoms in highly excited states with a very large principal quantum number (n≫1). Rydberg atoms are characterized by a number of peculiar physical properties as compared to atoms in the ground or a low excited state. They have a very small ionization potential (∝1/n2), the highly excited electron has a small orbital velocity (∝1/n), the radius (∝n2) is very large, the excited electron has a long orbital period (∝n3), and the radiation lifetime is very long (∝n3-5). At the same time the R. atom is very sensitive to perturbations from external fields in collisions with charged and neutral targets. In recent years, R. atoms have been observed in laboratory and cosmic conditions for n up to ˜1000, which means that the size amounts to about 0.1 mm, ˜106 times that of an atom in the ground state. The scope of this monograph is to familiarize the reader with today's approaches and methods for describing isolated R. atoms and ions, radiative transitions between highly excited states, and photoionization and photorecombination processes. The authors present a number of efficient methods for describing the structure and properties of R. atoms and calculating processes of collisions with neutral and charged particles as well as spectral-line broadening and shift of Rydberg atomic series in gases, cool and hot plasmas in laboratories and in astrophysical sources. Particular attention is paid to a comparison of theoretical results with available experimental data. The book contains 9 chapters. Chapter 1 gives an introduction to the basic properties of R. atoms (ions), Chapter 2 is devoted to an account of general methods describing an isolated Rydberg atom. Chapter 3 is focussed on the recent achievements in calculations of form factors and dipole matrix elements of different types of

Production of hollow atoms by high brightness x-ray sources and its applications

International Nuclear Information System (INIS)

Moribayashi, Kengo

2004-01-01

We study x-ray emissions from the (multi-)inner-shell states and hollow atoms of Si ions excited by high intensity x-ray sources. It is found that the x-ray number from multi-inner-shell excited states (1s 2 2s 2 2p k 3s 2 3p 2 , k=1-4) and hollow atoms (1s 2 2s 2 3p 2 ) is affected greatly by the high intensity short-pulse x-rays and little by weak intensity post-long pulse x-rays. The ratio of the x-ray intensities from hollow atoms to those from the multi-inner-shell excited states becomes almost independent of the pulses and dependent on the intensities of x-ray sources. This ratio may be used for the measurement of intensities of high intensity short pulse x-ray sources. (author)

The ionisation of the primeval plasma at the time of recombination

International Nuclear Information System (INIS)

Jones, B.J.T.; Wyse, R.F.G.

1984-09-01

We rederive the equations for the ionisation of the cosmic plasma during the recombination period, correcting some of the earlier work and refining some approximations inherent in those treatments and allow for the possibility that the universe may contain substantial amounts of non-baryonic matter (the cosmic density parameter Ωsub(T) may be greater than the baryonic contribution Ωsub(B)). The results are tabulated for various Ωsub(T)h 2 and Ωsub(B)h 2 and an assumed present day radiation temperature T 0 =2.7 K. (orig./WL)

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionisation mass spectrometry

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; Boer, de J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

Arbitrarily shaped high-coherence electron bunches from cold atoms

Science.gov (United States)

McCulloch, A. J.; Sheludko, D. V.; Saliba, S. D.; Bell, S. C.; Junker, M.; Nugent, K. A.; Scholten, R. E.

2011-10-01

Ultrafast electron diffractive imaging of nanoscale objects such as biological molecules and defects in solid-state devices provides crucial information on structure and dynamic processes: for example, determination of the form and function of membrane proteins, vital for many key goals in modern biological science, including rational drug design. High brightness and high coherence are required to achieve the necessary spatial and temporal resolution, but have been limited by the thermal nature of conventional electron sources and by divergence due to repulsive interactions between the electrons, known as the Coulomb explosion. It has been shown that, if the electrons are shaped into ellipsoidal bunches with uniform density, the Coulomb explosion can be reversed using conventional optics, to deliver the maximum possible brightness at the target. Here we demonstrate arbitrary and real-time control of the shape of cold electron bunches extracted from laser-cooled atoms. The ability to dynamically shape the electron source itself and to observe this shape in the propagated electron bunch provides a remarkable experimental demonstration of the intrinsically high spatial coherence of a cold-atom electron source, and the potential for alleviation of electron-source brightness limitations due to Coulomb explosion.

Progress in atomic spectroscopy

International Nuclear Information System (INIS)

Beyer, H.J.; Kleinpoppen, H.

1984-01-01

This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

Use of the Isomass 54E thermal ionisation mass spectrometer at AEE Winfrith. Part II: plutonium analysis

International Nuclear Information System (INIS)

Knight, A.P.

1982-06-01

This report describes the application of the Isomass 54E Thermal ionisation mass spectrometer for the isotopic analysis of plutonium, and gives details of the development of a method for quantitative determination of plutonium in sample solutions using isotopic dilution. A computer program for the control of the 54E is also described. Isotope dilution was used to compare results of plutonium content of twelve zebra reactor fuel pellets with results obtained by titrimetry. The Isomass 54E is shown to be capable of high precision analysis of plutonium sample solutions for both isotopic content and total plutonium concentration using an isotope dilution technique. (U.K.)

FREQUENCY OF CHROMOSOMAL ABERRATIONS AND MICRONUCLEI IN HORSE LYMPHOCYTES FOLLOWING IN VITRO EXPOSURE TO LOW DOSE IONISING RADIATION

Directory of Open Access Journals (Sweden)

Dunja Rukavina

2012-07-01

Full Text Available Ionising radiation is known to cause chromosomal instability, which is observed as increased frequency of chromosomal aberration and micronuclei. These are listed as reliable criteria in biological dosimetry. Numerous experiments conducted on both animal and plant models demonstrated that increase in radiation dosage is followed by increased mutation frequency, and that mutations occur even at the lowest exposure. We used horse blood in vitro irradiated by low doses of ionizing radiation. Cultivation of peripheral blood lymphocytes and micronucleus test were used as biomarkers of genetic damage. The observed aberrations were recorded and classified in accordance with the International System of Cytogenetic Nomenclature. Micronuclei were identified on the basis of criteria proposed by Fenech et al. (8. Analysis of chromosomal aberration showed increased frequency of aberrations in blood cultures exposed to 0,1 Gy and 0,2 Gy compared to the controls. Microscopic analysis of chromosomal damage in in vitro micronucleus test revealed that the applied radiation dose induced micronuclei while no binucleated cells with micronuclei were found in lymphocytes that were not irradiated. In this paper we analysed the influence of low dose ionising radiation on frequency of chromosomal aberration and micronuclei in horse lymphocytes following in vitro exposure to X-rays (0,1 Gy and 0,2 Gy. Key words: chromosomal aberrations, micronuclei, ionising radiation, horse lymphocytes

Single-atom lasing induced atomic self-trapping

International Nuclear Information System (INIS)

Salzburger, T.; Ritsch, H.

2004-01-01

We study atomic center of mass motion and field dynamics of a single-atom laser consisting of a single incoherently pumped free atom moving in an optical high-Q resonator. For sufficient pumping, the system starts lasing whenever the atom is close to a field antinode. If the field mode eigenfrequency is larger than the atomic transition frequency, the generated laser light attracts the atom to the field antinode and cools its motion. Using quantum Monte Carlo wave function simulations, we investigate this coupled atom-field dynamics including photon recoil and cavity decay. In the regime of strong coupling, the generated field shows strong nonclassical features like photon antibunching, and the atom is spatially confined and cooled to sub-Doppler temperatures. (author)

Improved communication, understanding of risk perception and ethics related to ionising radiation.

Science.gov (United States)

Perko, Tanja; Raskob, Wolfgang; Jourdain, Jean-Rene

2016-06-06

In Europe today, institutions, media and the general public exchange information about ionizing radiation and associated risks. However, communication about ionising radiation with the general public has to be further improved, as has been previously highlighted by international responses to the 2011 accident in Japan. This article reports the main activities and findings in this field from the following three FP7 projects: EAGLE, PREPARE and OPERRA and discussed by a broad spectrum of stakeholders at the conference RICOMET 2015. These projects, among other aims, also investigate how communication about ionising radiation in different fields could be improved and harmonised, how radiological risks are perceived, how to encourage ethical considerations in all fields of nuclear applications and what kind of transdisciplinary research is needed. The projects relate to several domains; the first relates to education, training and communication, the second to nuclear emergency preparedness and response, and the third to research and development in the radiation protection field. Incorporation of stakeholder engagement activities such as the RICOMET conference broadens social and ethical aspects and takes them into account during coordination activities as well as during core scientific and nuclear research and development performed in the projects. These activities offered opportunities for moving closer to a citizen-centred ideal of risk communication in particular and nuclear research and development in general.

Medical effects and risks of exposure to ionising radiation

International Nuclear Information System (INIS)

Mettler, Fred A

2012-01-01

Effects and risk from exposure to ionising radiation depend upon the absorbed dose, dose rate, quality of radiation, specifics of the tissue irradiated and other factors such as the age of the individual. Effects may be apparent almost immediately or may take decades to be manifest. Cancer is the most important stochastic effect at absorbed doses of less than 1 Gy. The risk of cancer induction varies widely across different tissues; however, the risk of fatal radiation-induced cancer for a general population following chronic exposure is about 5% Sv −1 . Quantification of cancer risk at doses of less than 0.1 Gy remains problematic. Hereditary risks from irradiation that might result in effects to offspring of humans appear to be much lower and any such potential risks can only be estimated from animal models. At high doses (over 1 Gy) cell killing and modification causes deterministic effects such as skin burns, and bone marrow depression, in which case immunosuppression becomes a critical issue. Acute whole body penetrating gamma irradiation at doses in excess of 2 Gy results in varying degrees of acute radiation sickness and doses over 10 Gy are usually lethal as a result of combined organ injury. (note)

Characterisation of ionisation chambers for a mixed radiation field and investigation of their suitability as radiation monitors for the LHC.

Science.gov (United States)

Theis, C; Forkel-Wirth, D; Perrin, D; Roesler, S; Vincke, H

2005-01-01

Monitoring of the radiation environment is one of the key tasks in operating a high-energy accelerator such as the Large Hadron Collider (LHC). The radiation fields consist of neutrons, charged hadrons as well as photons and electrons with energy spectra extending from those of thermal neutrons up to several hundreds of GeV. The requirements for measuring the dose equivalent in such a field are different from standard uses and it is thus necessary to investigate the response of monitoring devices thoroughly before the implementation of a monitoring system can be conducted. For the LHC, it is currently foreseen to install argon- and hydrogen-filled high-pressure ionisation chambers as radiation monitors of mixed fields. So far their response to these fields was poorly understood and, therefore, further investigation was necessary to prove that they can serve their function well enough. In this study, ionisation chambers of type IG5 (Centronic Ltd) were characterised by simulating their response functions by means of detailed FLUKA calculations as well as by calibration measurements for photons and neutrons at fixed energies. The latter results were used to obtain a better understanding and validation of the FLUKA simulations. Tests were also conducted at the CERF facility at CERN in order to compare the results with simulations of the response in a mixed radiation field. It is demonstrated that these detectors can be characterised sufficiently enough to serve their function as radiation monitors for the LHC.

Thermoluminescent properties of CVD diamond: applications to ionising radiation dosimetry

International Nuclear Information System (INIS)

Petitfils, A.

2007-09-01

Remarkable properties of synthetic diamond (human soft tissue equivalence, chemical stability, non-toxicity) make this material suitable for medical application as thermoluminescent dosimeter (TLD). This work highlights the interest of this material as radiotherapy TLD. In the first stage of this work, we looked after thermoluminescent (TL) and dosimetric properties of polycrystalline diamond made by Chemically Vapor Deposited (CVD) synthesis. Dosimetric characteristics are satisfactory as TLD for medical application. Luminescence thermal quenching on diamond has been investigated. This phenomenon leads to a decrease of dosimetric TL peak sensitivity when the heating rate increases. The second part of this work analyses the use of synthetic diamond as TLD in radiotherapy. Dose profiles, depth dose distributions and the cartography of an electron beam obtained with our samples are in very good agreement with results from an ionisation chamber. It is clearly shown that CVD) diamond is of interest to check beams of treatment accelerators. The use of these samples in a control of treatment with Intensity Modulated Radiation Therapy underlines good response of synthetic diamond in high dose gradient areas. These results indicate that CVD diamond is a promising material for radiotherapy dosimetry. (author)

Strategy for designing stable and powerful nitrogen-rich high-energy materials by introducing boron atoms.

Science.gov (United States)

Wu, Wen-Jie; Chi, Wei-Jie; Li, Quan-Song; Li, Ze-Sheng

2017-06-01

One of the most important aims in the development of high-energy materials is to improve their stability and thus ensure that they are safe to manufacture and transport. In this work, we theoretically investigated open-chain N 4 B 2 isomers using density functional theory in order to find the best way of stabilizing nitrogen-rich molecules. The results show that the boron atoms in these isomers are aligned linearly with their neighboring atoms, which facilitates close packing in the crystals of these materials. Upon comparing the energies of nine N 4 B 2 isomers, we found that the structure with alternating N and B atoms had the lowest energy. Structures with more than one nitrogen atom between two boron atoms had higher energies. The energy of N 4 B 2 increases by about 50 kcal/mol each time it is rearranged to include an extra nitrogen atom between the two boron atoms. More importantly, our results also show that boron atoms stabilize nitrogen-rich molecules more efficiently than carbon atoms do. Also, the combustion of any isomer of N 4 B 2 releases more heat than the corresponding isomer of N 4 C 2 does under well-oxygenated conditions. Our study suggests that the three most stable N 4 B 2 isomers (BN13, BN24, and BN34) are good candidates for high-energy molecules, and it outlines a new strategy for designing stable boron-containing high-energy materials. Graphical abstract The structural characteristics, thermodynamic stabilities, and exothermic properties of nitrogen-rich N 4 B 2 isomers were investigated by means of density functional theory.

Application of the binary-encounter theory to proton impact double ionization of atoms. [Cross sections

Energy Technology Data Exchange (ETDEWEB)

Kumar, A; Roy, B N [Bihar Univ. (India). Dept. of Physics

1977-10-21

Proton impact double ionisation of He has been investigated in the double-encounter model of Gryzinski (Phys. Rev.; 138A:305, 322 and 336 (1965)). The binary-encounter expressions developed by Vriens (Proc. Phys. Soc.; 89:13 (1966), Ibid 90:935 (1967)) along with an accurate quantum-mechanical velocity distribution for the bound electrons in both encounters have been used to obtain double-ionisation cross sections. These results have been compared with the experimental observations and earlier calculations by Gryzinski's method. The variation of sigmasub(+)/sigmasub(++) (single-ionisation cross section/double-ionisation cross section) with incident proton energy is also found to be in qualitative agreement with the experimentally observed variation.

Atom-counting in High Resolution Electron Microscopy:TEM or STEM - That's the question.

Science.gov (United States)

Gonnissen, J; De Backer, A; den Dekker, A J; Sijbers, J; Van Aert, S

2017-03-01

In this work, a recently developed quantitative approach based on the principles of detection theory is used in order to determine the possibilities and limitations of High Resolution Scanning Transmission Electron Microscopy (HR STEM) and HR TEM for atom-counting. So far, HR STEM has been shown to be an appropriate imaging mode to count the number of atoms in a projected atomic column. Recently, it has been demonstrated that HR TEM, when using negative spherical aberration imaging, is suitable for atom-counting as well. The capabilities of both imaging techniques are investigated and compared using the probability of error as a criterion. It is shown that for the same incoming electron dose, HR STEM outperforms HR TEM under common practice standards, i.e. when the decision is based on the probability function of the peak intensities in HR TEM and of the scattering cross-sections in HR STEM. If the atom-counting decision is based on the joint probability function of the image pixel values, the dependence of all image pixel intensities as a function of thickness should be known accurately. Under this assumption, the probability of error may decrease significantly for atom-counting in HR TEM and may, in theory, become lower as compared to HR STEM under the predicted optimal experimental settings. However, the commonly used standard for atom-counting in HR STEM leads to a high performance and has been shown to work in practice. Copyright © 2017 Elsevier B.V. All rights reserved.

Setting up and performance of a laser enhanced ionisation spectrometer

International Nuclear Information System (INIS)

Chandola, L.C.; Khanna, P.P.; Razvi, M.A.N.

1990-01-01

A laser enhanced ionisation (LEI) spectrometer has been successfuly set up around an excimer laser pumped dye laser. The performance of the spectrometer has been tested by analysing sodium in water solutions. A straight line working curve has been obtained in the concentration range of 1-1000 ng/ml of Na. The effect of parameters like laser power, ion collector electrode voltage and the load resistance on LEI signals has been investigated. The spectrometer is useful not only for analytical purposes but also for laser spectroscopic studies of species formed in flames, study of phenomenon of combustion etc. (author). 1 tab ., 10 figs., 5 refs

On the critical current of ionisation waves in gas discharges

International Nuclear Information System (INIS)

Sato, M.

1982-01-01

Measurement methods for determining the critical current of ionisation waves in gas discharge tubes are examined in detail. The conventional visual method which finds the current at which the waves disappear is erroneous since the criterion, 'observable', depends on the observing conditions. In the rigorous method it is defined as a current at which the linear growth rate of waves is zero. For the measured upper critical (Pupp) current of argon gas, close agreement is found between the results of other workers and those of the present author over a wide range of pressure-radius product 0.3 approximately equal to 60 Torr cm. (author)

ALARA - the contribution of the proposed new ionising radiations regulations

International Nuclear Information System (INIS)

Young, T.O.

1982-01-01

This paper describes the proposed regulatory requirements and appropriate guidance contained in the approved code of practice on ionising radiations which are designed to support and help reach the objective of keeping radiation doses as low as reasonably achievable. This is discussed against the background of factory legislation, and the way in which the form of the proposed legislation handles this topic is illustrated. The measures required by the proposed legislation are reviewed, both as direct measures designed to create a climate of dose reduction, and as general measures designed to achieve the same end by means of a wide range of requirements. (author)

D. C. electric field behavior of high lying states in atomic uranium

International Nuclear Information System (INIS)

Paisner, J.A.; Carlson, L.R.; Worden, E.F.; Johnson, S.A.; May, C.A.; Solarz, R.W.

1976-01-01

The effects of D. C. electric fields on high lying Rydberg and valence states in atomic uranium have been studied. Results of measurements of Stark shifts, lifetime lengthening via l-mixing, critical fields for ionization, barrier tunneling, and the appearance of zero-field parity forbidden transitions are presented for atomic uranium along with the observation of field induced autoionization of valence states. 3 figs

STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

Science.gov (United States)

2016-11-02

STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber...other than abstracts): Number of Peer-Reviewed Conference Proceeding publications (other than abstracts): Books Number of Manuscripts: 0.00Number of

Exploring Learners' Conceptual Resources: Singapore a Level Students' Explanations in the Topic of Ionisation Energy

Science.gov (United States)

Taber, Keith S.; Tan, Kim Chwee Daniel

2007-01-01

This paper describes findings from a study to explore Singapore A-level (Grades 11 and 12, 16-19 yr old) students' understanding of ionisation energy, an abstract and complex topic that is featured in school chemistry courses. Previous research had reported that students in the United Kingdom commonly use alternative notions based on the perceived…

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

New sources of cold atoms for atomic clocks

International Nuclear Information System (INIS)

Aucouturier, E.

1997-01-01

The purpose of this doctoral work is the realisation of new sources of cold cesium atoms that could be useful for the conception of a compact and high-performance atomic clock. It is based on experiences of atomic physics using light induced atomic manipulation. We present here the experiences of radiative cooling of atoms that have been realised at the Laboratoire de l'Horloge Atomique from 1993 to 1996. Firstly, we applied the techniques of radiative cooling and trapping of atoms in order to create a three-dimensional magneto-optical trap. For this first experience, we developed high quality laser sources, that were used for other experiments. We imagined a new configuration of trapping (two-dimensional magneto-optical trap) that was the basis for a cold atom source. This design gives the atoms a possibility to escape towards one particular direction. Then, we have extracted the atoms from this anisotropic trap in order to create a continuous beam of cold atoms. We have applied three methods of extraction. Firstly, the launching of atoms was performed by reducing the intensity of one of the cooling laser beams in the desired launching direction. Secondly, a frequency detuning between the two laser laser beams produced the launching of atoms by a so-called 'moving molasses'. The third method consisted in applying a static magnetic field that induced the launching of atoms in the direction of this magnetic field. At the same time, another research on cold atoms was initiated at the I.H.A. It consisted in cooling a large volume of atoms from a cell, using an isotropic light. This offers an interesting alternative to the traditional optical molasses. (author)

Counting Tm dopant atoms around GaN dots using high-angle annular dark field images

International Nuclear Information System (INIS)

Rouvière, J-L; Okuno, H; Jouneau, P H; Bayle-Guillemaud, P; Daudin, B

2011-01-01

High resolution Z-contrast STEM imaging is used to study the Tm doping of GaN quantum dots grown in AlN by molecular beam epitaxy (MBE). High-angle annular dark field (HAADF) imaging allows us to visualize directly individual Tm atoms in the AlN matrix and even to count the number of Tm atoms in a given AlN atomic column. A new visibility coefficient to determine quantitatively the number of Tm atoms in a given atomic column is introduced. It is based on locally integrated intensities rather than on peak intensities of HAADF images. STEM image simulations shows that this new visibility is less sensitive to the defocus-induced blurring or to the position of the Tm atom within the thin lamella. Most of the Tm atoms diffuse out of GaN dots. Tm atoms are found at different positions in the AlN matrix, (i) Above the wetting layer, Tm atoms are spread within a thickness of 14 AlN monolayers (MLs). (ii) Above the quantum dots all the Tm are located in the same plane situated at 2-3 MLs above the apex of the GaN dot, i.e. at a distance of 14 MLs from the wetting layer, (iii) In addition, Tm can diffuse very far from the GaN dot by following threading dislocations lines.

High-frequency multimodal atomic force microscopy

Directory of Open Access Journals (Sweden)

Adrian P. Nievergelt

2014-12-01

Full Text Available Multifrequency atomic force microscopy imaging has been recently demonstrated as a powerful technique for quickly obtaining information about the mechanical properties of a sample. Combining this development with recent gains in imaging speed through small cantilevers holds the promise of a convenient, high-speed method for obtaining nanoscale topography as well as mechanical properties. Nevertheless, instrument bandwidth limitations on cantilever excitation and readout have restricted the ability of multifrequency techniques to fully benefit from small cantilevers. We present an approach for cantilever excitation and deflection readout with a bandwidth of 20 MHz, enabling multifrequency techniques extended beyond 2 MHz for obtaining materials contrast in liquid and air, as well as soft imaging of delicate biological samples.

Absolute 3PO triple differential cross sections for electron-helium Wannier threshold ionisation

International Nuclear Information System (INIS)

Carruthers, D.R.J.; Crothers, D.S.F.

1992-01-01

The uniform semiclassical approximation of Crothers is employed to find a final-state 3 P O wave function for threshold electron impact ionisation of helium. The Kohn variational principle is applied perturbatively to evaluate the scattering amplitude and hence the absolute 3 P O contribution to the triple differential cross sections. These plus the previous absolute singlet results of Crothers are compared favourably with the relative experimental results of Selles et al. (orig.)

Charge-exchange-induced formation of hollow atoms in high-intensity laser-produced plasmas

Energy Technology Data Exchange (ETDEWEB)

Rosmej, F.B. [TU-Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Faenov, A.Ya.; Pikuz, T.A.; Magunov, A.I.; Skobelev, I.Yu. [Multicharged Ions Spectra Data Center of VNIIFTRI, Mendeleevo (Russian Federation); Auguste, T.; D' Oliveira, P.; Hulin, S.; Monot, P. [Commissariat a lEnergie Atomique DSM/DRECAM/SPAM, Gif-Sur-Yvette Cedex (France); Andreev, N.E.; Chegotov, M.V.; Veisman, M.E. [High Energy Density Research Centre, Institute of High Temperatures of Russian Academy of Sciences, Moscow (Russian Federation)

1999-03-14

For the first time registration of high-resolution soft x-ray emission and atomic data calculations of hollow-atom dielectronic satellite spectra of highly charged nitrogen have been performed. Double-electron charge-exchange processes from excited states are proposed for the formation of autoionizing levels nln'l' in high-intensity laser-produced plasmas, when field-ionized ions penetrate into the residual gas. Good agreement is found between theory and experiment. Plasma spectroscopy with hollow ions is proposed and a temperature diagnostic for laser-produced plasmas in the long-lasting recombining regime is developed. (author). Letter-to-the-editor.

Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch

International Nuclear Information System (INIS)

Baker, S H; Roy, M; Thornton, S C; Binns, C

2012-01-01

We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu 1-x Au x matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ∼2.5 ± 0.3 μ B /atom. (paper)

Charge transfer and excitation in high-energy ion-atom collisions

International Nuclear Information System (INIS)

Schlachter, A.S.; Berkner, K.H.; McDonald, R.J.

1986-11-01

Coincidence measurements of charge transfer and simultaneous projectile electron excitation provide insight into correlated two-electron processes in energetic ion-atom collisions. Projectile excitation and electron capture can occur simultaneously in a collision of a highly charged ion with a target atom; this process is called resonant transfer and excitation (RTE). The intermediate excited state which is thus formed can subsequently decay by photon emission or by Auger-electron emission. Results are shown for RTE in both the K shell of Ca ions and the L shell of Nb ions, for simultaneous projectile electron loss and excitation, and for the effect of RTE on electron capture

Various high precision measurements of pressure in atomic energy industry

International Nuclear Information System (INIS)

Aritomi, Masanori; Inoue, Akira; Hosoma, Takashi; Tanaka, Izumi; Gabane, Tsunemichi.

1987-01-01

As for the pressure measurement in atomic energy industry, it is mostly the measurement using differential pressure transmitters and pressure transmitters for process measurement with the general accuracy of measurement of 0.2 - 0.5 % FS/year. However, recently for the development of nuclear fusion reactors and the establishment of nuclear fuel cycle accompanying new atomic energy technology, there are the needs of the pressure measurement having higher accuracy of 0.01 % FS/year and high resolution, and quartz vibration type pressure sensors appeared. New high accuracy pressure measurement techniques were developed by the advance of data processing and the rationalization of data transmission. As the results, the measurement of the differential pressure of helium-lithium two-phase flow in the cooling system of nuclear fusion reactors, the high accuracy measuring system for the level of plutonium nitrate and other fuel substance in tanks in fuel reprocessing and conversion, the high accuracy measurement of atmospheric pressure and wind velocity in ducts, chimneys and tunnels in nuclear facilities and so on became feasible. The principle and the measured data of quartz vibration type pressure sensors are shown. (Kako, I.)

Nitrogen Atom Transfer From High Valent Iron Nitrides

Energy Technology Data Exchange (ETDEWEB)

Johnson, Michael D. [New Mexico State Univ., Las Cruces, NM (United States); Smith, Jeremy M. [Indiana Univ., Bloomington, IN (United States)

2015-10-14

This report describes the synthesis and reactions of high valent iron nitrides. Organonitrogen compounds such as aziridines are useful species for organic synthesis, but there are few efficient methods for their synthesis. Using iron nitrides to catalytically access these species may allow for their synthesis in an energy-and atom-efficient manner. We have developed a new ligand framework to achieve these goals as well as providing a method for inducing previously unknown reactivity.

EPR spectroscopy for the detection of foods treated with ionising radiation

International Nuclear Information System (INIS)

Stachowicz, W.; Burlinska, G.; Michalik, J.; Dziedzic-Goclawska, A.; Ostrowski, K.

1996-01-01

The advantage of electron paramagnetic resonance spectroscopy (EPR or ESR) as a tool for the control of irradiated food lies in its sensitivity and accuracy. Ionising radiation produces, in irradiated materials, paramagnetic species of different kinds, i.e. radicals, radical-ions and paramagnetic centres, which can be measured by EPR but most of them are not stable enough to be used for the detection of irradiation. It is because radiation-induced paramagnetic species are thermodynamically less stable than surrounding molecules and take part in fast radiolytic reactions leading to the formation of final diamagnetic products that they are not detectable by the EPR method. Most of organic radicals produced by radiation in the liquid phase ae unstable but if the unpaired electron is incorporated into the complex polymeric system as in peptides and polysaccharides and is structurally isolated from the water, its stability is markedly increased. Since 1954 it is known that ionising radiation produces paramagnetic entities in biological materials, cells and tissues and some are stable enough to be observed by EPR spectroscopy at room temperature. The present paper describes and discusses that part of results obtained by this group during the period of ADMIT activity (1989-94) which are original and may be useful to those who will be working in the near future on the development of uniform control systems for the detection of irradiated food. The intention was to focus attention on these facts and data which influence the certainty of the detection in both positive and negative manner. (author)

Angular distributions of low kinetic energy photoelectrons in one- and two-photon ionisation of rare gas atoms

International Nuclear Information System (INIS)

O'Keeffe, P; Bolognesi, P; Avaldi, L; Richter, R; Moise, A; Cleva, P De; Mihelic, A

2012-01-01

The angular distributions of electrons emitted in the photoionisation of rare gas atoms using one and two photons are presented. The one-photon results show that these differential measurements can provide complementary information on the photoionisation event with respect to the measurement of the total absorption cross section while the two photon ionization allows additional parameters to be extracted from the experiments thus permitting a more complete description of the photoionisation dynamics.

Radiation protection instrument 1993

International Nuclear Information System (INIS)

1993-04-01

The Radiation Protection Instrument, 1993 (Legislative Instrument 1559) prescribes the powers and functions of the Radiation Protection Board established under the Ghana Atomic Energy Commission by the Atomic Energy Commission (Amendment) Law, 1993 (P.N.D.C. Law 308). Also included in the Legislative Instrument are schedules on control and use of ionising radiation and radiation sources as well as procedures for notification, licensing and inspection of ionising radiation facilities. (EAA)

High-flux cold rubidium atomic beam for strongly-coupled cavity QED

Energy Technology Data Exchange (ETDEWEB)

Roy, Basudev [Indian Institute of Science Education and Research, Kolkata (India); University of Maryland, MD (United States); Scholten, Michael [University of Maryland, MD (United States)

2012-08-15

This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D{sup +} magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 10{sup 10} atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.

Surface modification of highly oriented pyrolytic graphite by reaction with atomic nitrogen at high temperatures

International Nuclear Information System (INIS)

Zhang Luning; Pejakovic, Dusan A.; Geng Baisong; Marschall, Jochen

2011-01-01

Dry etching of {0 0 0 1} basal planes of highly oriented pyrolytic graphite (HOPG) using active nitridation by nitrogen atoms was investigated at low pressures and high temperatures. The etching process produces channels at grain boundaries and pits whose shapes depend on the reaction temperature. For temperatures below 600 deg. C, the majority of pits are nearly circular, with a small fraction of hexagonal pits with rounded edges. For temperatures above 600 deg. C, the pits are almost exclusively hexagonal with straight edges. The Raman spectra of samples etched at 1000 deg. C show the D mode near 1360 cm -1 , which is absent in pristine HOPG. For deep hexagonal pits that penetrate many graphene layers, neither the surface number density of pits nor the width of pit size distribution changes substantially with the nitridation time, suggesting that these pits are initiated at a fixed number of extended defects intersecting {0 0 0 1} planes. Shallow pits that penetrate 1-2 graphene layers have a wide size distribution, which suggests that these pits are initiated on pristine graphene surfaces from lattice vacancies continually formed by N atoms. A similar wide size distribution of shallow hexagonal pits is observed in an n-layer graphene sample after N-atom etching.

Revisiting Bragg's X-ray microscope: Scatter based optical transient grating detection of pulsed ionising radiation

International Nuclear Information System (INIS)

Fullagar, Wilfred K.; Paganin, David M.; Hall, Chris J.

2011-01-01

Transient optical gratings for detecting ultrafast signals are routine for temporally resolved photochemical investigations. Many processes can contribute to the formation of such gratings; we indicate use of optically scattering centres that can be formed with highly variable latencies in different materials and devices using ionising radiation. Coherent light scattered by these centres can form the short-wavelength-to-optical-wavelength, incoherent-to-coherent basis of a Bragg X-ray microscope, with inherent scope for optical phasing. Depending on the dynamics of the medium chosen, the way is open to both ultrafast pulsed and integrating measurements. For experiments employing brief pulses, we discuss high-dynamic-range short-wavelength diffraction measurements with real-time optical reconstructions. Applications to optical real-time X-ray phase-retrieval are considered. -- Research highlights: → It is timely that the concept of Bragg's X-ray microscope be revisited. → Transient gratings can be used for X-ray all-optical information processing. → Applications to optical real-time X-ray phase-retrieval are considered.

Atom-atom collision cascades localization

International Nuclear Information System (INIS)

Kirsanov, V.V.

1980-01-01

The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

Characterisation of the Muon Beams for the Muon Ionisation Cooling Experiment

CERN Document Server

Adams, D.; Alekou, A.; Apollonio, M.; Asfandiyarov, R.; Back, J.; Barber, G.; Barclay, P.; de Bari, A.; Bayes, R.; Bayliss, V.; Bertoni, R.; Blackmore, V.J.; Blondel, A.; Blot, S.; Bogomilov, M.; Bonesini, M.; Booth, C.N.; Bowring, D.; Boyd, S.; Bradshaw, T.W.; Bravar, U.; Bross, A.D.; Capponi, M.; Carlisle, T.; Cecchet, G.; Charnley, G.; Cobb, J.H.; Colling, D.; Collomb, N.; Coney, L.; Cooke, P.; Courthold, M.; Cremaldi, L.M.; DeMello, A.; Dick, A.; Dobbs, A.; Dornan, P.; Fayer, S.; Filthaut, F.; Fish, A.; Fitzpatrick, T.; Fletcher, R.; Forrest, D.; Francis, V.; Freemire, B.; Fry, L.; Gallagher, A.; Gamet, R.; Gourlay, S.; Grant, A.; Graulich, J.S.; Griffiths, S.; Hanlet, P.; Hansen, O.M.; Hanson, G.G.; Harrison, P.; Hart, T.L.; Hartnett, T.; Hayler, T.; Heidt, C.; Hills, M.; Hodgson, P.; Iaciofano, A.; Ishimoto, S.; Kafka, G.; Kaplan, D.M.; Karadzhov, Y.; Kim, Y.K.; Kolev, D.; Kuno, Y.; Kyberd, P.; Lau, W.; Leaver, J.; Leonova, M.; Li, D.; Lintern, A.; Littlefield, M.; Long, K.; Lucchini, G.; Luo, T.; Macwaters, C.; Martlew, B.; Martyniak, J.; Middleton, S.; Moretti, A.; Moss, A.; Muir, A.; Mullacrane, I.; Nebrensky, J.J.; Neuffer, D.; Nichols, A.; Nicholson, R.; Nugent, J.C.; Onel, Y.; Orestano, D.; Overton, E.; Owens, P.; Palladino, V.; Palmer, R.B.; Pasternak, J.; Pastore, F.; Pidcott, C.; Popovic, M.; Preece, R.; Prestemon, S.; Rajaram, D.; Ramberger, S.; Rayner, M.A.; Ricciardi, S.; Richards, A.; Roberts, T.J.; Robinson, M.; Rogers, C.; Ronald, K.; Rubinov, P.; Rucinski, R.; Rusinov, I.; Sakamoto, H.; Sanders, D.A.; Santos, E.; Savidge, T.; Smith, P.J.; Snopok, P.; Soler, F.J.P.; Stanley, T.; Summers, D.J.; Takahashi, M.; Tarrant, J.; Taylor, I.; Tortora, L.; Torun, Y.; Tsenov, R.; Tunnell, C.D.; Vankova, G.; Verguilov, V.; Virostek, S.; Vretenar, M.; Walaron, K.; Watson, S.; White, C.; Whyte, C.G.; Wilson, A.; Wisting, H.; Zisman, M.

2013-01-01

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.5--2.3 \\pi mm-rad horizontally and 0.6--1.0 \\pi mm-rad vertically, a horizontal dispersion of 90--190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

Energy Technology Data Exchange (ETDEWEB)

Adams, D.; et al.,

2013-10-01

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.5--2.3 \\pi mm-rad horizontally and 0.6--1.0 \\pi mm-rad vertically, a horizontal dispersion of 90--190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

Atomic collisions related to atomic laser isotope separation

International Nuclear Information System (INIS)

Shibata, Takemasa

1995-01-01

Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

Molecular mechanisms of plant response to ionising radiation. Exploration of the glucosinolate role in the anti-oxidative response

International Nuclear Information System (INIS)

Gicquel, M.

2012-01-01

Terrestrial organisms are exposed to low doses of ionising radiation from natural or anthropogenic sources. The major effects of the radiations are due to DNA deterioration and water radiolysis which generates an oxidative stress by free radical production. Plants constitute good models to study the effects of ionising radiations and the search of antioxidant molecules because of their important secondary metabolism. Thus this thesis, funded by the Brittany region, characterized the physiological and molecular response of the model plant Arabidopsis thaliana to low (10 Gy) and moderate (40 Gy) doses of ionising radiation, and was therefore interested in glucosinolates, characteristic compounds of the Brassicaceae family. The global proteomic and transcriptomic studies carried out on this model revealed (1) a common response for both doses dealing with the activation of DNA repair mechanisms, cell cycle regulation and protection of cellular structures; (2) an adjustment of the energetic metabolism and an activation of secondary compounds biosynthesis (i.e. glucosinolates and flavonoids) after the 10 Gy dose; (3) an induction of enzymatic control of ROS, the regulation of cellular components recycling and of programmed cell death after the 40 Gy dose. The potential anti-oxidative role of glucosinolates was then explored. The in vitro anti-oxidative power of some glucosinolates and their derivative products were demonstrated. Their modulating effects against irradiation-induced damages were then tested in vivo by simple experimental approaches. The importance of the glucosinolate level to give a positive or negative effect was demonstrated. (author)

Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging

Directory of Open Access Journals (Sweden)

Millar A Harvey

2011-07-01

Full Text Available Abstract Matrix-Assisted Laser Desorption/Ionisation (MALDI mass spectrometry imaging (MSI uses the power of high mass resolution time of flight (ToF mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

High atomic weight isotope separator

International Nuclear Information System (INIS)

Book, D.L.

1978-01-01

A continuously operating device is described which separates one isotopic species of a given element from a mixture. The given element is vaporized and formed into a neutral beam containing the isotopes desired to be separated. The plasma is accelerated through a laser beam which is formed by two separate lasers which operate in the continuous wave mode in which the beams are as nearly as possible in the same beam path. The two laser output beams excite and ionize the isotope of interest while leaving the remaining atoms unaffected. The ionized isotopes are then separated from the beam by an electrostatic deflection technique and the unaffected atoms continue on in their path and are directed to a recovery device

Isotopic separation of 235U and 238U in an atomic beam with selective two-step photo-ionisation

International Nuclear Information System (INIS)

Boehm, H.D.V.

1977-01-01

The present work gives a report on investigations on isotope separation of 235 U and 238 U by means of selective two-stage photo-ionization on atomic uranium. An atomic beam of sufficient particle density was produced by dissociation of URe 2 in an electron beam heated tungsten furnace at a temperature of 2.500 k. A continuously operated rhodamin-69 dye laser with a maximum output of 120 mW and about 50 mHz band width in one-made operation was used for selective excitation from the ground state. From this state of excitation, ionization resulted achieving a light power of 1.8 W below 3030 A in the reaction volume. The measured separation factors show that the laser method enables the enrichment of uranium to the required valve of three or more percent 235 U for light water reactors in a single separation step. The hyperfine structure could be considerably better resolved compared to earlier investigations, so that it was possible for the first time to identify and measure hitherto unobserved weak components. (orig.) [de

Ionisation differential cross section measurements for N2 at low incident energy in coplanar and non-coplanar geometries

International Nuclear Information System (INIS)

Sakaamini, Ahmad; Murray, Andrew James; Amami, Sadek; Madison, Don; Ning, Chuangang

2016-01-01

Ionisation triple differential cross sections have been determined experimentally and theoretically for the neutral molecule N 2 over a range of geometries from coplanar to the perpendicular plane. Data were obtained at incident electron energies ∼10 and ∼20 eV above the ionisation potential of the 3 σ g , 1 π u and 2 σ g states, using both equal and non-equal outgoing electron energies. The data were taken with the incident electron beam in the scattering plane ( ψ = 0°), at 45° to this plane and orthogonal to the plane ( ψ = 90°). The set of nine measured differential cross sections at a given energy were then inter-normalised to each other. The data are compared to new calculations using various distorted wave methods, and differences between theory and experiment are discussed. (paper)

Scattering of highly excited atoms

International Nuclear Information System (INIS)

Raith, W.

1980-01-01

Experimental methods to excite atomic beams into Rydberg states and the first results of collision experiments with such beams are reported. For further information see hints under relevant topics. (orig.) [de

Atom optics

International Nuclear Information System (INIS)

Balykin, V. I.; Jhe, W.

1999-01-01

Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

Design and performance of a high intensity copper atom beam source nozzle for use in inelastic atom--atom collision experiments

International Nuclear Information System (INIS)

Santavicca, D.A.

1975-01-01

The research was aimed at developing a neutral copper atom beam source which could be used to study the collision cross sections for electronic excitation of neutral copper atoms in collision with neutral argon atoms. Of particular interest is the excitation from the ground state to the two upper laser levels at 3.80 and 3.82 electron volts

Thermally and optically stimulated luminescence of AlN-Y2O3 ceramics after ionising irradiation

DEFF Research Database (Denmark)

Trinkler, L.; Bos, A.J.J.; Winkelman, A.J.M.

1999-01-01

, an essential drawback of AlN-Y2O3 is its high fading rate. Special attention has been focused on understanding and improving the fading properties. In particular, the influence of the ceramics production conditions and the additive concentration on the fading rate have been studied. Experimental results......Thermally (TL) and optically stimulated luminescence (OSL) were studied in AlN-Y2O3 ceramics after irradiation with ionising radiation. The extremely high TL sensitivity (approximately 60 times the sensitivity of LiF:Mg,Tl (TLD-100)) makes AlN-Y2O3 ceramics attractive as a TLD material. However...... on spectral properties and thermal evolution of OSL are also presented. The stimulation spectrum covers the spectral range from green to infrared light. A combination of thermal and optical stimulation allowed a correlation to be found between parameters of OSL and TL after the same irradiation dose...

Studies of Non-Targeted Effects of Ionising Radiation

International Nuclear Information System (INIS)

Oleg V Belyakov; Heli Mononen; Marjo Peraelae

2006-01-01

The discovery of ionising radiation induced non-targeted effects is important for understanding the dose-response mechanisms relevant to low dose irradiation in vivo. One important question is whether the non-targeted effects relates to a protective mechanism or whether, conversely, it amplifies the number of cells damaged by the isolated radiation tracks of low dose exposures leading to an increased risk of carcinogenesis. One theory supported by the experimental data obtained during this project is that the main functions of the non-targeted effects are to decrease the risk of transformation in a multicellular organism exposed to radiation. Differences in the gene expression profiles, temporal and spatial patterns of key proteins expressed in directly irradiated and bystander cells may determine how the cells ultimately respond to low doses of radiation. Such a mechanism of co-operative response would make the tissue system much more robust. (N.C.)

Studies of Non-Targeted Effects of Ionising Radiation

Energy Technology Data Exchange (ETDEWEB)

Oleg V Belyakov; Heli Mononen; Marjo Peraelae [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland)

2006-07-01

The discovery of ionising radiation induced non-targeted effects is important for understanding the dose-response mechanisms relevant to low dose irradiation in vivo. One important question is whether the non-targeted effects relates to a protective mechanism or whether, conversely, it amplifies the number of cells damaged by the isolated radiation tracks of low dose exposures leading to an increased risk of carcinogenesis. One theory supported by the experimental data obtained during this project is that the main functions of the non-targeted effects are to decrease the risk of transformation in a multicellular organism exposed to radiation. Differences in the gene expression profiles, temporal and spatial patterns of key proteins expressed in directly irradiated and bystander cells may determine how the cells ultimately respond to low doses of radiation. Such a mechanism of co-operative response would make the tissue system much more robust. (N.C.)

Activity standardisation of 18F and ionisation chamber calibration for nuclear medicine

International Nuclear Information System (INIS)

Schrader, H.; Klein, R.; Kossert, K.

2007-01-01

Primary activity standardisations were performed on solutions of 18 F using 4πβ-γ coincidence counting and liquid scintillation counting (LSC) according to the CIEMAT/NIST method. A β + -emission probability of 96.86% was used for both methods. The various standardised 18 F solutions were measured in ionisation chambers of the Physikalisch-Technische Bundesanstalt (PTB) and compared by determining radionuclide calibration factors. Already in 2001 an 18 F solution had been standardised at the PTB and compared with the results of nine national metrology institutes (NMIs), using the ISOCAL IV secondary radionuclide calibrators of the National Physical Laboratory (NPL) as transfer instruments and a 68 Ge check source solution. These results were linked to the International Reference System (SIR) at the Bureau International des Poids et Mesures (BIPM) by aliquots of solutions sent by the Laboratoire National Henri Becquerel (BNM-LNHB) and the NPL. Further on, in 2005, PTB sent an aliquot of an 18 F solution to the SIR for ionisation chamber measurements. A value of the equivalent activity was determined and included in the key comparison database (KCDB). The recent PTB value of the equivalent activity of the SIR is in good agreement with the key comparison reference value determined from five NMIs. These results confirm that the standardisation of 18 F solutions can be achieved with the accuracy required for use in nuclear medicine and, in particular, for applications in positron emission tomography (PET)

Atom Skimmers and Atom Lasers Utilizing Them

Science.gov (United States)

Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

2005-01-01

Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

Lethal Effect on Bacterium of Decay of Incorporated Radioactive Atoms ({sup 3}H, {sup 14}C, {sup 32}P); Effet Letal de la Desintegration d'Atomes Radioactifs ({sup 3}H, {sup 14}C, {sup 32}P) Incorpores dans une Bacterie

Energy Technology Data Exchange (ETDEWEB)

Apelgot, Sonia [Laboratoire Curie, Institut du Radium, Paris (France)

1968-06-15

macromolecules d'une bacterie provoque sa sterilisation par les ionisations produites par la particule {beta}{sup -} emise; la transmutation ne joue qu'un role negligeable. Cette auto-irradiation est du meme ordre qu'une irradiation X. Elle est influencee d'une facon comparable par les memes facteurs: temperature, radioprotecteur, radiosensibilite des souches. La desintegration des atomes de {sup 14}C ou de {sup 32}P incorpores dans un ADN bacterien est letale par l'effet de la transmutation; les ionisations produites par les particules {beta}{sup -} emises ne jouent qu'un tole negligeable. Les courbes de survie aux transmutations de {sup 32}P dependent des conditions experimentales. Certains des resultats obtenus avec le {sup 32}P se rapprochent d'une irradiation X: action de la temperature, des capteurs de radicaux, de l'oxygene; d'autres rappellent ceux d'une irradiation UV : influencedesconditionsdecroissance. Les experiences de comparaison faites avec le {sup 32}P permettent de dire que l'energie de recul de la transmutation n'est pas le phenomene responsable de l'effet letal observe. La comparaison des resultats obtenus apres irradiation X ou desintegration des atomes de {sup 3}H ou de {sup 32}P incorpores dans l'ADN de bacteries d'une meme souche E. coli indique que l'efficacite d'une transmutation de {sup 32}P est environ quatre fois plus grande que celle d'une ionisation produite au hasard dans ce meme ADN. (author)

Superradiators created atom by atom

Science.gov (United States)

Meschede, Dieter

2018-02-01

High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

Recoil-ion momentum spectroscopy

International Nuclear Information System (INIS)

Ullrich, J.; Moshammer, R.; Doerner, R.; Jagutzki, O.; Mergel, V.; Schmidt-Boecking, H.; Spielberger, L.

1996-10-01

High-resolution recoil-ion momentum spectroscopy (RIMS) is a novel technique to determine the charge state and the complete final momentum vector P R of a recoiling target ion emerging from an ionising collision of an atom with any kind of radiation. It offers a unique combination of superior momentum resolution in all three spatial directions of ΔP R = 0.07 a.u. with a large detection solid angle of ΔΩ R /4π≥ 98%. Recently, low-energy electron analysers based on rigorously new concepts and reaching similar specifications were successfully integrated into RIM spectrometers yielding so-called ''reaction microscopes''. Exploiting these techniques, a large variety of atomic reactions for ion, electron, photon and antiproton impact have been explored in unprecedented detail and completeness. Among them first kinematically complete experiments on electron capture, single and double ionisation in ion-atom collisions at projectile energies between 5 keV and 1.4 GeV. Double photoionisation of He has been investigated at energies E γ close to the threshold (E γ = 80 eV) up to E γ = 58 keV. At E γ >8 keV the contributions to double ionisation after photoabsorption and Compton scattering were kinematically separated for the first time. These and many other results will be reviewed in this article. In addition, the experimental technique is described in some detail and emphasis is given to envisage the rich future potential of the method in various fields of atomic collision physics with atoms, molecules and clusters. (orig.)

Influence of SNP Polymorphisms in DNA Repair Genes on the Level of Persistent Damage in Human Lymphocytes After Exposure to 2 Gy of Ionising Radiation

International Nuclear Information System (INIS)

Milic, M.; Rozgaj, R.; Kasuba, V.; Kubelka, D.; Angelini, S.; Hrelia, P.

2011-01-01

Variation in cell response to ionising radiation could be result of changes in gene expression and/or polymorphisms of DNA repair genes. The aim of the study was to estimate the DNA damage level in human lymphocytes after exposure to 2 Gy of ionising radiation. Medical workers occupationally exposed to low doses of ionising radiation (N = 20) and matched controls (N 20) were genotyped for polymorphic hOGG1, XRCC1, APE1, XPD10, XPD23, XRCC3, PARP1 and MGMT genes. Micronucleus (MN) test was used for the estimation of DNA damage before and after radiation. Incidence of MN in irradiated samples positively correlated with age and negatively with polymorphic variants of XPD23. Significant difference was observed between irradiated homozygotes (HO) and heterozygotes (HE). HO and HE APE1 differed in MN before exposure. HO and polymorphic variants of XPD10 differed in MN after exposure. Gender showed different MN in the exposed group after exposure. Age correlated positively with MN after exposure, working probation and received dose. Multiple regression analysis revealed connection between polymorphic variants of APE1 and XRCC3 with MN before exposure. These results confirm the value of micronucleus assay in DNA damage estimation and suggest possible use of polymorphic genes in monitoring of individuals professionaly exposed to ionising radiation. (author)

A front-end ASIC for ionising radiation monitoring with femto-amp capabilities

International Nuclear Information System (INIS)

Voulgari, E.; Noy, M.; Anghinolfi, F.; Perrin, D.; Krummenacher, F.; Kayal, M.

2016-01-01

An ultra-low leakage current Application Specific Integrated Circuit (ASIC) called Utopia (Ultralow Picoammeter) has been designed and fabricated in AMS 0.35 μm CMOS, in order to be used as the front-end for ionising radiation monitoring at CERN. It is based on the topology of a Current to Frequency Converter (CFC) through charge balancing and demonstrates a wide dynamic range of 8.5 decades without range changing. Due to a design aimed at minimising input leakage currents, input currents as low as 01 fA can be measured

Effects of finite temperature on two-photon transitions in a Rydberg atom in a high-Q cavity

International Nuclear Information System (INIS)

Puri, R.R.; Joshi, A.

1989-01-01

The effects of cavity temperature on an effective two-level atom undergoing two-photon transitions in a high-Q cavity are investigated. The quantum statistical properties of the field and the dynamical properties of the atom in this case are studied and compared with those for an atom making one-photon transitions between the two levels. The analysis is based on the solution of the equation for the density matrix in the secular approximation which is known to be a valid approximation in the case of a Rydberg atom in a high-Q cavity. (orig.)

Systematic observation of tunneling field-ionization in highly excited Rb Rydberg atoms

International Nuclear Information System (INIS)

Kishimoto, Y.; Tada, M.; Kominato, K.; Shibata, M.; Yamada, S.; Haseyama, T.; Ogawa, I.; Funahashi, H.; Yamamoto, K.; Matsuki, S.

2002-01-01

Pulsed field ionization of high-n (90≤n≤150) manifold states in Rb Rydberg atoms has been investigated in high slew-rate regime. Two peaks in the field ionization spectra were systematically observed for the investigated n region, where the field values at the lower peak do not almost depend on the excitation energy in the manifold, while those at the higher peak increase with increasing excitation energy. The fraction of the higher peak component to the total ionization signals increases with increasing n, exceeding 80% at n=147. Characteristic behavior of the peak component and the comparison with theoretical predictions indicate that the higher peak component is due to the tunneling process. The obtained results show that the tunneling process plays increasingly the dominant role at such highly excited nonhydrogenic Rydberg atoms

EXANA, a program for analysing EXtended energy loss fine structures, EXELFS spectra

International Nuclear Information System (INIS)

Tafreshi, M.A.; Bohm, C.; Csillag, S.

1992-09-01

This paper is a users guide and reference manual for the EXANA, an IBM or IBM compatible PC-based program used for analysing extended fine structures occurring on the high energy side of the ionisation edges. The RDF (Radial Distance Function) obtained from this analysis contains information about the number, distance, and type of the nearby atoms, as well as the inelastic mean free path and disorder in distances from the centre atom to the atoms in a atomic shell around it. The program can be made available on request. (au)

Calculations with the quasirelativistic local-spin-density-functional theory for high-Z atoms

International Nuclear Information System (INIS)

Guo, Y.; Whitehead, M.A.

1988-01-01

The generalized-exchange local-spin-density-functional theory (LSD-GX) with relativistic corrections of the mass velocity and Darwin terms has been used to calculate statistical total energies for the neutral atoms, the positive ions, and the negative ions for high-Z elements. The effect of the correlation and relaxation correction on the statistical total energy is discussed. Comparing the calculated results for the ionization potentials and electron affinities for the atoms (atomic number Z from 37 to 56 and 72 to 80) with experiment, shows that for the atoms rubidium to barium both the LSD-GX and the quasirelativistic LSD-GX, with self-interaction correction, Gopinathan, Whitehead, and Bogdanovic's Fermi-hole parameters [Phys. Rev. A 14, 1 (1976)], and Vosko, Wilk, and Nusair's correlation correction [Can. J. Phys. 58, 1200 (1980)], are very good methods for calculating ionization potentials and electron affinities. For the atoms hafnium to mercury the relativistic effect has to be considered

Fast, High-Precision Optical Polarization Synthesizer for Ultracold-Atom Experiments

Science.gov (United States)

Robens, Carsten; Brakhane, Stefan; Alt, Wolfgang; Meschede, Dieter; Zopes, Jonathan; Alberti, Andrea

2018-03-01

We present a technique for the precision synthesis of arbitrary polarization states of light with a high modulation bandwidth. Our approach consists of superimposing two laser light fields with the same wavelength, but with opposite circular polarizations, where the phase and the amplitude of each light field are individually controlled. We find that the polarization-synthesized beam reaches a degree of polarization of 99.99%, which is mainly limited by static spatial variations of the polarization state over the beam profile. We also find that the depolarization caused by temporal fluctuations of the polarization state is about 2 orders of magnitude smaller. In a recent work, Robens et al. [Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices, Phys. Rev. Lett. 118, 065302 (2017), 10.1103/PhysRevLett.118.065302] demonstrated an application of the polarization synthesizer to create two independently controllable optical lattices which trap atoms depending on their internal spin state. We use ultracold atoms in polarization-synthesized optical lattices to give an independent, in situ demonstration of the performance of the polarization synthesizer.

Comparative evaluation of different approaches to environmental protection against ionising radiation in view of practicability and consistency

International Nuclear Information System (INIS)

Steiner, M.; Hornung, L.; Mundigl, S.; Kirchner, G.

2006-01-01

International organisations, including ICRP, IAEA and UNSCEAR, and the international scientific community are currently engaged in work on the protection of non-human species against ionising radiation as a complement to the existing framework centred on humans. The basic ideas and conceptual approaches developed during the last decade substantially agree with each other. The EC funded FASSET project (Framework for Assessment of Environmental Impact) summarizes and reviews the current knowledge of radiation effects on biota, provides basic dosimetric models for fauna and flora and suggests an assessment framework. Protection of the environment against ionising radiation, on the one hand, aims to close a conceptual gap in radiation protection. Therefore, current frameworks for environmental protection conceptually follow radiation protection of man. On the other hand, preservation of natural resources, habitats and the biological diversity are common objectives of environmental protection against radioactive as well as chemical pollutants, suggesting an integrated approach based on the fundamental ideas of conventional environmental protection. In essence, a conceptual framework encompassing protection of man as well as of fauna and flora against chemical and radioactive pollutants would be highly desirable in view of coherence, consistency and transparency. Such an umbrella concept communicates the positive message that similar issues are treated in a conceptually similar manner, thus facilitating scientific justification and public communication and increasing acceptance. This paper discusses different concepts and approaches to radiation protection of man, radiation protection of non-human biota and environmental protection against chemical pollutants, identifies common principles and differences, addresses conflicting requirements and evaluates the feasibility and limitations of such an encompassing framework. (authors)

Atomic physics with high-brightness synchrotron x-ray sources

International Nuclear Information System (INIS)

Jones, K.W.; Johnson, B.M.; Meron, M.

1985-11-01

A description of atomic physics experiments that we intend to carry out at the National Synchrotron Light Source is given. Emphasis is given to work that investigates the properties of multiply charged ions. The use of a synchrotron storage ring for highly charged heavy ions is proposed as a way to produce high current beams which will make possible experiments to study the photoexcitation and ionization of multiply charged ions for the first time. Experiments along the same lines which are feasible at the proposed Advanced Light Source are considered briefly. 7 refs., 2 figs

Isotope Dilution - Thermal Ionisation Mass Spectrometric Analysis for Tin in a Fly Ash Material

International Nuclear Information System (INIS)

Hernandez, C.; Fernandez, M.; Quejido, A. L.

2006-01-01

Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis has been applied to the determination of tin in a fly ash sample supplied by the EC Joint Research Centre (Ispra, Italy). The proposed procedure includes the silica gel/phosphoric acid technique for tin thermal ionisation activation and a strict heating protocol for isotope ratio measurements. Instrumental mass discrimination factor has been previously determined measuring a natural tin standard solution. Spike solutions has been prepared from 112Sn-enriched metal and quantified by reverse isotope dilution analysis. Two sample aliquots were spiked and tin was extracted with 4,5 M HCI during 25 min ultrasound esposure time. Due to the complex matrix of this fly ash material, a two-steps purification stage using ion-exchange chromatography was required prior TIMS analysis. Obtained results for the two sample-spike blends (10,10 + - 0,55 y 10,50 + - 0,64 imolg-1) are comprarable, both value and uncertainty. Also a good reproducibility is observed between measurements. The proposed ID-TIMS procedure, as a primary method and due to the lack of fly ash reference material certified for tin content, can be used to validate more routine methodologies applied to tin determination in this kind of materials. (Author) 75 refs

Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations

Energy Technology Data Exchange (ETDEWEB)

Alonzo, F. [Laboratory of Environmental Modelling, DEI/SECRE/LME, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 159, BP3, 13115 St-Paul-lez-Durance Cedex (France); Laboratory of Radioecology and Ecotoxicology, DEI/SECRE/LRE, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache Building 186, BP3, 13115 St-Paul-lez-Durance Cedex (France)], E-mail: frederic.alonzo@irsn.fr; Hertel-Aas, T. [Department of Plant and Environmental Sciences, P.O. Box 5003, Norwegian University of Life Sciences, 1432 Aas (Norway); Gilek, M. [School of Life Sciences, Soedertoern University College, 14189 Huddinge (Sweden); Gilbin, R. [Laboratory of Radioecology and Ecotoxicology, DEI/SECRE/LRE, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache Building 186, BP3, 13115 St-Paul-lez-Durance Cedex (France); Oughton, D.H. [Department of Plant and Environmental Sciences, P.O. Box 5003, Norwegian University of Life Sciences, 1432 Aas (Norway); Garnier-Laplace, J. [Laboratory of Radioecology and Ecotoxicology, DEI/SECRE/LRE, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache Building 186, BP3, 13115 St-Paul-lez-Durance Cedex (France)

2008-09-15

This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h{sup -1}). Population extinction was predicted at 43 mGy h{sup -1}. In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h{sup -1}), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.

Calculated ionisation potentials to determine the oxidation of vanillin precursors by lignin peroxidase.

OpenAIRE

Have, ten, R.; Rietjens, I.M.C.M.; Hartmans, S.; Swarts, H.J.; Field, J.A.

1998-01-01

In view of the biocatalytic production of vanillin, this research focused on the lignin peroxidase (LiP) catalysed oxidation of naturally occurring phenolic derivatives: O-methyl ethers, O-acetyl esters, and O-glucosyl ethers. The ionisation potential (IP) of a series of model compounds was calculated and compared to their experimental conversion by LiP, defining a relative IP threshold of approximately 9.0 eV. Based on this threshold value only the O-acetyl esters and glucosides of isoeugeno...

Lactobacilli and ionising radiation: an example of the application to meat and meat products

International Nuclear Information System (INIS)

Holzapfel, W.H.

1992-01-01

Ionising radiation provides a practical pasteurisation method for the terminal treatment of refrigerated vacuum-packaged meat products with the aim of shelf life extension. However, the relatively high radiation resistance (γ-D 10 = 0.70-1.2 kGy) of typical meat Lactobacilli, especially Lb. sake, selectively favours their total domination after treatments with 5 kGy. Typical meat strains show higher resistance (in term of γ-D 10 values the decimal reduction value due to irradiation) in the log (exponential) than in the stationary phase. This phenomenon was observed both in semi-synthetic broth and in meat, and may be explained in terms of a DNA repair mechanism operative during the exponential phase. Packaging under different gas atmospheres resulted in increased resistance to radiation in presence of N 2 , whilst the highest death rate was observed in presence of CO 2 . (orig.) [de

Annotated bibliography of highly ionized atoms of importance to plasmas

International Nuclear Information System (INIS)

Schmieder, R.W.

1975-04-01

A bibliography is presented of the literature on highly ionized atoms which have relevance to plasmas. The bibliography is annotated with keywords, and indexed by subjects and authors. It should be of greatest use to researchers working on the problems of impurity cooling and diagnostics of CTR plasmas. (U.S.)

Generation and amplification of a high-order sideband induced by two-level atoms in a hybrid optomechanical system

Science.gov (United States)

Liu, Zeng-Xing; Xiong, Hao; Wu, Ying

2018-01-01

It is quite important to enhance and control the optomechanically induced high-order sideband generation to achieve low-power optical comb and high-sensitivity sensing with an integrable structure. Here we present and analyze a proposal for enhancement and manipulation of optical nonlinearity and high-order sideband generation in a hybrid atom-cavity optomechanical system that is coherently driven by a bichromatic input field consisting of a control field and a probe field and that works beyond the perturbative regime. Our numerical analysis with experimentally achievable parameters confirms that robust high-order sideband generation and typical spectral structures with nonperturbative features can be created even under weak driven fields. The dependence of the high-order sideband generation on the atomic parameters are also discussed in detail, including the decay rate of the atoms and the coupling parameter between the atoms and the cavity field. We show that the cutoff order as well as the amplitude of the higher-order sidebands can be well tuned by the atomic coupling strength and the atomic decay rate. The proposed mechanism of enhancing optical nonlinearity is quite general and can be adopted to optomechanical systems with different types of cavity.

Atom localization via controlled spontaneous emission in a five-level atomic system

International Nuclear Information System (INIS)

Wang Zhiping; Yu Benli; Zhu Jun; Cao Zhigang; Zhen Shenglai; Wu Xuqiang; Xu Feng

2012-01-01

We investigate the one- and two-dimensional atom localization behaviors via spontaneous emission in a coherently driven five-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of atom localization behaviors can be significantly improved via adjusting the system parameters. More importantly, the two-dimensional atom localization patterns reveal that the maximal probability of finding an atom within the sub-wavelength domain of the standing waves can reach unity when the corresponding conditions are satisfied. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization. - Highlights: ► One- and two-dimensional atom localization behaviors via spontaneous emission in five-level atoms are investigated. ► An assisting radio-frequency field is used to control the atom localization behaviors. ► High-precision and high-resolution two-dimensional atom localization can be realized in this scheme.

Accuracy evaluation of the prescribed calibration factors for ionisation chambers belonging to radiotherapy centres

International Nuclear Information System (INIS)

Mohd Taufik Dolah; Supian Samat; Taiman Kadni

1999-01-01

Air kerma and exposure calibration factors of 14 ionisation chambers belonging to ten local radiotherapy centres have been determined by SSDL in the recent last ten month (1/10/1998 - 31/7/1999). The results obtained were compared either with previous SSDL results, or the chambers certificate values. The range of the percentage deviations obtained was -1.70% to 1.18%, which lies between the IAEA accepted value of range ±3.5%. (author)

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

Energy Technology Data Exchange (ETDEWEB)

Adams, D.; Barclay, P.; Bayliss, V.; Bradshaw, T.W.; Courthold, M.; Francis, V.; Fry, L.; Hayler, T.; Hills, M.; Lintern, A.; Macwaters, C.; Nichols, A.; Preece, R.; Ricciardi, S.; Rogers, C.; Stanley, T.; Tarrant, J.; Watson, S.; Wilson, A. [Harwell Oxford, STFC Rutherford Appleton Laboratory, Didcot (United Kingdom); Adey, D.; Back, J.; Boyd, S.; Harrison, P.; Pidcott, C.; Taylor, I. [University of Warwick, Department of Physics, Coventry (United Kingdom); Alekou, A.; Apollonio, M.; Barber, G.; Colling, D.; Dobbs, A.; Dornan, P.; Fayer, S.; Fish, A.; Hunt, C.; Leaver, J.; Long, K.; Martyniak, J.; Middleton, S.; Pasternak, J.; Richards, A.; Santos, E.; Savidge, T.; Takahashi, M. [Imperial College London, Department of Physics, Blackett Laboratory, London (United Kingdom); Asfandiyarov, R.; Blondel, A.; Graulich, J.S.; Karadzhov, Y.; Verguilov, V.; Wisting, H. [Universite de Geneve, DPNC, Section de Physique, Geneva (Switzerland); De Bari, A.; Cecchet, G. [Sezione INFN Pavia (Italy); Dipartimento di Fisica Nucleare e Teorica, Pavia (Italy); Bayes, R.; Forrest, D.; Nugent, J.C.; Soler, F.J.P.; Walaron, K. [The University of Glasgow, School of Physics and Astronomy, Glasgow (United Kingdom); Bertoni, R.; Bonesini, M.; Lucchini, G. [Sezione INFN Milano Bicocca (Italy); Dipartimento di Fisica G. Occhialini, Milano (Italy); Blackmore, V.J.; Carlisle, T.; Cobb, J.H.; Lau, W.; Rayner, M.A.; Tunnell, C.D. [University of Oxford, Department of Physics, Oxford (United Kingdom); Blot, S.; Kim, Y.K. [University of Chicago, Enrico Fermi Institute, Chicago, IL (United States); Bogomilov, M.; Kolev, D.; Rusinov, I.; Tsenov, R.; Vankova, G. [St. Kliment Ohridski University of Sofia, Department of Atomic Physics, Sofia (Bulgaria); Booth, C.N.; Hodgson, P.; Nicholson, R.; Overton, E.; Robinson, M.; Smith, P.J. [University of Sheffield, Department of Physics and Astronomy, Sheffield (United Kingdom); Bowring, D.; DeMello, A.; Gourlay, S.; Li, D.; Prestemon, S.; Virostek, S.P.; Zisman, M.S. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Bravar, U. [University of New Hampshire, Durham, NH (United States); Bross, A.D.; Fitzpatrick, T.; Leonova, M.; Moretti, A.; Neuffer, D.; Popovic, M.; Rubinov, P.; Rucinski, R. [Fermilab, Batavia, IL (United States); Capponi, M.; Iaciofano, A.; Orestano, D.; Pastore, F.; Tortora, L. [Sezione INFN Roma Tre e Dipartimento di Fisica, Roma (Italy); Charnley, G.; Collomb, N.; Gallagher, A.; Grant, A.; Griffiths, S.; Hartnett, T.; Martlew, B.; Moss, A.; Muir, A.; Mullacrane, I.; Owens, P.; White, C. [STFC Daresbury Laboratory, Cheshire (United Kingdom); Coney, L.; Fletcher, R.; Hanson, G.G.; Heidt, C. [University of California, Riverside, CA (United States); Cooke, P.; Gamet, R. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Cremaldi, L.M.; Hart, T.L.; Luo, T.; Sanders, D.A.; Summers, D.J. [University of Mississippi, Oxford, MS (United States); Dick, A.J.; Ronald, K.; Whyte, C.G. [University of Strathclyde, Department of Physics, Glasgow (United Kingdom); Filthaut, F. [NIKHEF, Amsterdam (Netherlands); Freemire, B.; Hanlet, P.; Kafka, G.; Kaplan, D.M.; Rajaram, D.; Snopok, P.; Torun, Y. [Illinois Institute of Technology, Chicago, IL (United States); Hansen, O.M.; Ramberger, S.; Vretenar, M. [CERN, Geneva (Switzerland); Ishimoto, S. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Kuno, Y.; Sakamoto, H. [Osaka University, Graduate School of Science, Department of Physics, Toyonaka, Osaka (Japan); Kyberd, P.; Littlefield, M.; Nebrensky, J.J. [Brunel University, Uxbridge (United Kingdom); Onel, Y. [University of Iowa, Department of Physics and Astronomy, Iowa City, IA (United States); Palladino, V. [Universita Federico II, Sezione INFN Napoli (Italy); Dipartimento di Fisica, Napoli (Italy); Palmer, R.B. [Brookhaven National Laboratory, Upton, NY (US); Roberts, T.J. [Muons, Inc., Batavia, IL (US); Collaboration: The MICE Collaboration

2013-10-15

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2-2.3 {pi} mm-rad horizontally and 0.6-1.0 {pi} mm-rad vertically, a horizontal dispersion of 90-190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE. (orig.)

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

International Nuclear Information System (INIS)

Adams, D.; Barclay, P.; Bayliss, V.; Bradshaw, T.W.; Courthold, M.; Francis, V.; Fry, L.; Hayler, T.; Hills, M.; Lintern, A.; Macwaters, C.; Nichols, A.; Preece, R.; Ricciardi, S.; Rogers, C.; Stanley, T.; Tarrant, J.; Watson, S.; Wilson, A.; Adey, D.; Back, J.; Boyd, S.; Harrison, P.; Pidcott, C.; Taylor, I.; Alekou, A.; Apollonio, M.; Barber, G.; Colling, D.; Dobbs, A.; Dornan, P.; Fayer, S.; Fish, A.; Hunt, C.; Leaver, J.; Long, K.; Martyniak, J.; Middleton, S.; Pasternak, J.; Richards, A.; Santos, E.; Savidge, T.; Takahashi, M.; Asfandiyarov, R.; Blondel, A.; Graulich, J.S.; Karadzhov, Y.; Verguilov, V.; Wisting, H.; De Bari, A.; Cecchet, G.; Bayes, R.; Forrest, D.; Nugent, J.C.; Soler, F.J.P.; Walaron, K.; Bertoni, R.; Bonesini, M.; Lucchini, G.; Blackmore, V.J.; Carlisle, T.; Cobb, J.H.; Lau, W.; Rayner, M.A.; Tunnell, C.D.; Blot, S.; Kim, Y.K.; Bogomilov, M.; Kolev, D.; Rusinov, I.; Tsenov, R.; Vankova, G.; Booth, C.N.; Hodgson, P.; Nicholson, R.; Overton, E.; Robinson, M.; Smith, P.J.; Bowring, D.; DeMello, A.; Gourlay, S.; Li, D.; Prestemon, S.; Virostek, S.P.; Zisman, M.S.; Bravar, U.; Bross, A.D.; Fitzpatrick, T.; Leonova, M.; Moretti, A.; Neuffer, D.; Popovic, M.; Rubinov, P.; Rucinski, R.; Capponi, M.; Iaciofano, A.; Orestano, D.; Pastore, F.; Tortora, L.; Charnley, G.; Collomb, N.; Gallagher, A.; Grant, A.; Griffiths, S.; Hartnett, T.; Martlew, B.; Moss, A.; Muir, A.; Mullacrane, I.; Owens, P.; White, C.; Coney, L.; Fletcher, R.; Hanson, G.G.; Heidt, C.; Cooke, P.; Gamet, R.; Cremaldi, L.M.; Hart, T.L.; Luo, T.; Sanders, D.A.; Summers, D.J.; Dick, A.J.; Ronald, K.; Whyte, C.G.; Filthaut, F.; Freemire, B.; Hanlet, P.; Kafka, G.; Kaplan, D.M.; Rajaram, D.; Snopok, P.; Torun, Y.; Hansen, O.M.; Ramberger, S.; Vretenar, M.; Ishimoto, S.; Kuno, Y.; Sakamoto, H.; Kyberd, P.; Littlefield, M.; Nebrensky, J.J.; Onel, Y.; Palladino, V.; Palmer, R.B.; Roberts, T.J.

2013-01-01

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2-2.3 π mm-rad horizontally and 0.6-1.0 π mm-rad vertically, a horizontal dispersion of 90-190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE. (orig.)

New high-throughput material-exploration system based on combinatorial chemistry and electrostatic atomization

International Nuclear Information System (INIS)

Fujimoto, K.; Takahashi, H.; Ito, S.; Inoue, S.; Watanabe, M.

2006-01-01

As a tool to facilitate future material explorations, our group has developed a new combinatorial system for the high-throughput preparation of compounds made up of more than three components. The system works in two steps: the atomization of a liquid by a high electric field followed by deposition to a grounded substrate. The combinatorial system based on this method has plural syringe pumps. The each starting materials are fed through the syringe pumps into a manifold, thoroughly mixed as they pass through the manifold, and atomized from the tip of a stainless steel nozzle onto a grounded substrate

Atomic layer deposition of high-mobility hydrogen-doped zinc oxide

NARCIS (Netherlands)

Macco, B.; Knoops, H.C.M.; Verheijen, M.A.; Beyer, W.; Creatore, M.; Kessels, W.M.M.

2017-01-01

In this work, atomic layer deposition (ALD) has been employed to prepare high-mobility H-doped zinc oxide (ZnO:H) films. Hydrogen doping was achieved by interleaving the ZnO ALD cycles with H2 plasma treatments. It has been shown that doping with H2 plasma offers key advantages over traditional

Testing of the effect of the entry beam tube windows of the silicon detectors of the ionisation radiation

International Nuclear Information System (INIS)

Kopestansky, J.; Tykva, R.; Stanek, S.

1995-01-01

This paper deals with testing of the entry beam tube windows of the silicon detectors of the ionisation radiation with surface barrier.The influence of the parameters of basic material and modified technologic preparation on the size and homogeneity of the windows was tested

Analysis of atomic distribution in as-fabricated Zircaloy-2 claddings by atom probe tomography under high-energy pulsed laser

Energy Technology Data Exchange (ETDEWEB)

Sawabe, T., E-mail: sawabe@criepi.denken.or.jp [Central Research Institute of Electric Power Industry (CRIEPI), Iwado Kita 2-11-1, Komae, Tokyo 201-8511 (Japan); Sonoda, T.; Kitajima, S. [Central Research Institute of Electric Power Industry (CRIEPI), Iwado Kita 2-11-1, Komae, Tokyo 201-8511 (Japan); Kameyama, T. [Tokai University, Department of Nuclear Engineering, Kitakaname 4-1-1, Hiratsuka, Kanagawa 259-1292 (Japan)

2013-11-15

The properties of second-phase particles (SPPs) in Zircaloy-2 claddings are key factors influencing the corrosion resistance of the alloy. The chemical compositions of Zr (Fe, Cr){sub 2} and Zr{sub 2}(Fe, Ni) SPPs were investigated by means of pulsed laser atom probe tomography. In order to prevent specimen fracture and to analyse wide regions of the specimen, the pulsed laser energy was increased to 2.0 nJ. This gave a high yield of average of 3 × 10{sup 7} ions per specimen. The Zr (Fe, Cr){sub 2} SPPs contained small amounts of Ni and Si atoms, while in Zr{sub 2}(Fe, Ni) SPPs almost all the Si was concentrated and the ratio of Zr: (Fe + Ni + Si) was 2:1. Atomic concentrations of the Zr-matrix and the SPPs were identified by two approaches: the first by using all the visible peaks of the mass spectrum and the second using the representative peaks with the natural abundance of the corresponding atoms. It was found that the change in the concentration between the Zr-matrix and the SPPs can be estimated more accurately by the second method, although Sn concentration in the Zr{sub 2}(Fe, Ni) SPPs is slightly overestimated.

The specific features of self-action of high-power laser radiation propagating through a fully ionised cold plasma and the development of modulation instability

International Nuclear Information System (INIS)

Aleshkevich, Viktor A; Kartashev, Ya V; Vysloukh, Victor A

2000-01-01

The specific features of the propagation of soliton-like light beams through a fully ionised two-dimensional cold plasma are considered employing analytical and numerical methods commonly used in nonlinear optics. Exact soliton profiles for the lower and upper soliton branches are found numerically in the presence of optical bistability. It is shown that the interaction of incoherent soliton-like laser beams in such a plasma may result both in the destruction of one of the beams and in production of new ones. The regime of the modulation instability of a plane wave propagating through a cold laser-produced plasma is studied. (nonlinear optical phenomena)

High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies

International Nuclear Information System (INIS)

Cross, J.B.; Blais, N.C.

1988-01-01

A high intensity (10 19 O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 10 22 O-atoms/cm 2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO 2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O 2 mixtures. Visible and infrared photon flux levels of 1 watt/cm 2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 /times/ 10/sup /minus/24/ cm /+-/ 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H 2 O, NO, CO 2 ). Teflon reacts with ∼0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs

Protection of the environment from ionising radiation: ethical issues

International Nuclear Information System (INIS)

Oughton, Deborah

2003-01-01

The paper identifies some of the main ethical issues concerning the protection of the environment from radiation and suggests ways in which ethics can aid in developing a system of protection. After a presentation of background on ethical theory and environmental ethics, three main issues related to environmental protection are discussed: First, the question of valuing the environment and implications for the definition of harm and monetary valuation of environmental goods; second, difficulties with scientific uncertainty and applications of the precautionary principle; and third, issues concerned with the distribution of risk and its relevance fo participation in decision-making. In summary, the paper argues that there are strong ethical grounds to provide for the protection of the environment and that, all other things being equal, there is no reason to treat ionising radiation differently to other environmental stressors

Protection of the environment from ionising radiation: ethical issues.

Science.gov (United States)

Oughton, Deborah

2003-01-01

The paper identifies some of the main ethical issues concerning the protection of the environment from radiation and suggests ways in which ethics can aid in developing a system of protection. After a presentation of background on ethical theory and environmental ethics, three main issues related to environmental protection are discussed: First, the question of valuing the environment and implications for the definition of harm and monetary valuation of environmental goods; second, difficulties with scientific uncertainty and applications of the precautionary principle; and third, issues concerned with the distribution of risk and its relevance for participation in decision-making. In summary, the paper argues that there are strong ethical grounds to provide for the protection of the environment and that, all other things being equal, there is no reason to treat ionising radiation differently to other environmental stressors. Copyright 2002 Elsevier Science Ltd.

Characteristics of single-atom trapping in a magneto-optical trap with a high magnetic-field gradient

International Nuclear Information System (INIS)

Yoon, Seokchan; Choi, Youngwoon; Park, Sangbum; Ji, Wangxi; Lee, Jai-Hyung; An, Kyungwon

2007-01-01

A quantitative study on characteristics of a magneto-optical trap with a single or a few atoms is presented. A very small number of 85 Rb atoms were trapped in a micron-size magneto-optical trap with a high magnetic-field gradient. In order to find the optimum condition for a single-atom trap, we have investigated how the number of atoms and the size of atomic cloud change as various experimental parameters, such as a magnetic-field gradient and the trapping laser intensity and detuning. The averaged number of atoms was measured very accurately with a calibration procedure based on the single-atom saturation curve of resonance fluorescence. In addition, the number of atoms in a trap could be controlled by suppressing stochastic loading events by means of a real-time active feedback on the magnetic-field gradient

Analysis of the monosaccharide composition of water-soluble polysaccharides from Sargassum fusiforme by high performance liquid chromatography/electrospray ionisation mass spectrometry.

Science.gov (United States)

Wu, Xiaodan; Jiang, Wei; Lu, Jiajia; Yu, Ying; Wu, Bin

2014-02-15

Sargassum fusiforme (hijiki) is the well-known edible algae, whose polysaccharides have been proved to possess interesting bioactivities like antitumor, antioxidant, antimicrobial and immunomodulatory activities. A facile and sensitive method based on high-performance liquid chromatography method of pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) coupled with electrospray ionisation mass spectrometry (HPLC/ESI-MS) has been established for the analysis of the monosaccharide composition of polysaccharides in S. fusiforme. Monosaccharides have been converted into PMP-labelled derivatives with aqueous ammonia as a catalyst at 70 °C for 30 min. The optimisation of the pre-column derivatization process was studied. The LODs of the monosaccharides were in the range from 0.01 to 0.02 nmol. PMP-labelled mixture of monosaccharides has been well separated by a reverse-phase HPLC and detected by on-line ESI-MS method under optimised conditions. The mobile phase of elution system was chosen as acetonitrile (solvent A) and 20mM aqueous ammonium acetate (solvent B) (pH 3.0) with Zorbax XDB-C18 column at 30 °C for the separation of the monosaccharide derivatives. Identification of the monosaccharides composition was carried out by analysis with mass spectral behaviour and chromatography characteristics of 1-phenyl-3-methyl-5-pyrazolone (PMP) labelled monosaccharides. All PMP-labelled derivatives display high chemical stabilities, whose regular MS fragmentation is specific for reducing labelled sugars. The result showed that the S. fusiforme polysaccharide consisted of mannose, glucose, galactose, xylose, fucose and glucuronic acid or galacturonic acid, or both uronic acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Asymmetric-detection time-stretch optical microscopy (ATOM) for ultrafast high-contrast cellular imaging in flow

Science.gov (United States)

Wong, Terence T. W.; Lau, Andy K. S.; Ho, Kenneth K. Y.; Tang, Matthew Y. H.; Robles, Joseph D. F.; Wei, Xiaoming; Chan, Antony C. S.; Tang, Anson H. L.; Lam, Edmund Y.; Wong, Kenneth K. Y.; Chan, Godfrey C. F.; Shum, Ho Cheung; Tsia, Kevin K.

2014-01-01

Accelerating imaging speed in optical microscopy is often realized at the expense of image contrast, image resolution, and detection sensitivity – a common predicament for advancing high-speed and high-throughput cellular imaging. We here demonstrate a new imaging approach, called asymmetric-detection time-stretch optical microscopy (ATOM), which can deliver ultrafast label-free high-contrast flow imaging with well delineated cellular morphological resolution and in-line optical image amplification to overcome the compromised imaging sensitivity at high speed. We show that ATOM can separately reveal the enhanced phase-gradient and absorption contrast in microfluidic live-cell imaging at a flow speed as high as ~10 m/s, corresponding to an imaging throughput of ~100,000 cells/sec. ATOM could thus be the enabling platform to meet the pressing need for intercalating optical microscopy in cellular assay, e.g. imaging flow cytometry – permitting high-throughput access to the morphological information of the individual cells simultaneously with a multitude of parameters obtained in the standard assay. PMID:24413677

Occupational radiation injuries from ionising rays recorded in the Federal Republic of Germany during the period between 1953 and 1979

International Nuclear Information System (INIS)

Soffke, R.

1986-01-01

An evaluation of 218 occupational diseases, which were reported between 1953 and 1979 and officially recognised as being caused by ionising rays, showed these to be made up chiefly by skin disorders (61%, equally distributed over acute and chronic forms), even though considerable percentage shares were also calculated for haematological ailments (15%) and bronchial carcinomas developed by uranium miners. There was a total of 42 deaths, 32 of which were ascribed to uranium mining and 10 to haematological diseases. In all, the annual rate of occupational diseases attributed to ionising rays shows a tendency to decline, even though the number of individuals exposed to radiation is increasing. The incidence of radiation injuries was calculated to be in the order of 0.01% for persons at risk of occupational radiation exposure. (orig./EDB) [de

Controlling interactions between highly magnetic atoms with Feshbach resonances.

Science.gov (United States)

Kotochigova, Svetlana

2014-09-01

This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

Atomic hydrogen reactor

International Nuclear Information System (INIS)

Massip de Turville, C.M.D.

1982-01-01

Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

Atomic spectroscopy and highly accurate measurement: determination of fundamental constants

International Nuclear Information System (INIS)

Schwob, C.

2006-12-01

This document reviews the theoretical and experimental achievements of the author concerning highly accurate atomic spectroscopy applied for the determination of fundamental constants. A pure optical frequency measurement of the 2S-12D 2-photon transitions in atomic hydrogen and deuterium has been performed. The experimental setting-up is described as well as the data analysis. Optimized values for the Rydberg constant and Lamb shifts have been deduced (R = 109737.31568516 (84) cm -1 ). An experiment devoted to the determination of the fine structure constant with an aimed relative uncertainty of 10 -9 began in 1999. This experiment is based on the fact that Bloch oscillations in a frequency chirped optical lattice are a powerful tool to transfer coherently many photon momenta to the atoms. We have used this method to measure accurately the ratio h/m(Rb). The measured value of the fine structure constant is α -1 = 137.03599884 (91) with a relative uncertainty of 6.7*10 -9 . The future and perspectives of this experiment are presented. This document presented before an academic board will allow his author to manage research work and particularly to tutor thesis students. (A.C.)

Health effects of low dose ionising radiation - recent advances and their implications

International Nuclear Information System (INIS)

1987-01-01

The proceedings of this unusual interdisciplinary conference encompass the work of doctors, industrialists and civil servants. The discussion covers the investigation and quantification of dose response relationships for the various damaging effects of low level ionising radiation and a unified system for expressing biological damage, together with the results of epidemiological studies using models and data from the UK, Europe, Australia and the USA (including data base systems for assembling and validating data), the effects of background radiation (gamma ray and radon exposure), clustering studies, safety standards, radioactive waste discharge control and limitation through legislation and the monitoring of radioactivity in food. (author)

Germany (Federal Republic). Ministry of the Interior. Order on protection against damage due to ionising radiation. Radiation Protectin Order. StrlSchV 20 Oct. 1976

International Nuclear Information System (INIS)

1977-02-01

The order is arranged in parts, entitled: introductory provisions; control provisions (handling radioactive matter, the carriage of radioactive matter, the import and export of radioactive matter, the construction and operation of installation for generating ionising radiation, employees and other persons working under supervision, design approval); safety regulations (general regulations, protection of the population and the environment against the hazards of ionising radiation, occupational exposure to radiation, radiation protection areas, physical protection and control, medical supervision, instruments for measuring radiation, other safety regulations); fines; and final provisions. (U.K.)

Search for long-lived, multi-charged particles in pp collisions at √s = 7 TeV using the ATLAS detector

Czech Academy of Sciences Publication Activity Database

Aad, G.; Abajyan, T.; Abbott, B.; Böhm, Jan; Chudoba, Jiří; Gallus, Petr; Gunther, Jaroslav; Jakoubek, Tomáš; Juránek, Vojtěch; Kepka, Oldřich; Kupčo, Alexander; Kůs, Vlastimil; Lokajíček, Miloš; Marčišovský, Michal; Mikeštíková, Marcela; Myška, Miroslav; Němeček, Stanislav; Růžička, Pavel; Schovancová, Jaroslava; Šícho, Petr; Staroba, Pavel; Svatoš, Michal; Taševský, Marek; Tic, Tomáš; Vrba, Václav

2013-01-01

Roč. 722, 4-5 (2013), s. 305-323 ISSN 0370-2693 R&D Projects: GA MŠk(CZ) LG13009 Institutional support: RVO:68378271 Keywords : ATLAS * CERN * high-energy collider experiment * long-lived particle * highly ionising * new physics * multiple electric charges Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 6.019, year: 2013

Risk of death among children of atomic bomb survivors after 62 years of follow-up: a cohort study.

Science.gov (United States)

Grant, Eric J; Furukawa, Kyoji; Sakata, Ritsu; Sugiyama, Hiromi; Sadakane, Atsuko; Takahashi, Ikuno; Utada, Mai; Shimizu, Yukiko; Ozasa, Kotaro

2015-10-01

No clear epidemiological hereditary effects of radiation exposure in human beings have been reported. However, no previous studies have investigated mortality into middle age in a population whose parents were exposed to substantial amounts of radiation before conception. We assessed mortality in children of the atomic bomb survivors after 62 years of follow-up. In this prospective cohort study, we assessed 75 327 singleton children of atomic bomb survivors in Hiroshima and Nagasaki and unexposed controls, born between 1946 and 1984, and followed up to Dec 31, 2009. Parental gonadal doses of radiation from the atomic bombings were the primary exposures. The primary endpoint was death due to cancer or non-cancer disease, based on death certificates. Median follow-up was 54·3 years (IQR 45·4-59·3). 5183 participants died from disease. The mean age of the 68 689 surviving children at the end of follow-up was 53·1 years (SD 7·9) with 15 623 (23%) older than age 60 years. For parents who were exposed to a non-zero gonadal dose of radiation, the mean dose was 264 mGy (SD 463). We detected no association between maternal gonadal radiation exposure and risk of death caused by cancer (hazard ratio [HR] for 1 Gy change in exposure 0·891 [95% CI 0·693-1·145]; p=0·36) or risk of death caused by non-cancer diseases (0·973 [0·849-1·115]; p=0·69). Likewise, paternal exposure had no effect on deaths caused by cancer (0·815 [0·614-1·083]; p=0·14) or deaths caused by non-cancer disease (1·103 [0·979-1·241]; p=0·12). Age or time between parental exposure and delivery had no effect on risk of death. Late effects of ionising radiation exposure include increased mortality risks, and models of the transgenerational effects of radiation exposure predict more genetic disease in the children of people exposed to radiation. However, children of people exposed to the atomic bombs in Hiroshima and Nagasaki had no indications of deleterious health effects after 62

A cascade method of training for the revised CEGB Radiological Safety Rules and the Ionising Radiations Regulations 1985

International Nuclear Information System (INIS)

Jackson, J.R.; John, P.G.L.

1986-01-01

In order to achieve compliance with the Ionising Radiations Regulations 1985 the CEGB has introduced a revised set of Radiological Safety Rule. These Rules are for implementation at all sites under the Board's control where ionising radiations are used. It was a requirement that the new Safety Rules be brought into operation on a common date and to a consistent standard of performance throughout the industry; this necessitated a considerable training programme to familiarise and inform some 8,000 staff working at a large number of locations. The training week of identified groups of staff varied widely, according to their different levels of authority and responsibility. The paper sets out the means by which the chosen cascade method of training was selected and developed, and gives details of the modular package of training material which was produced. It also relates how the management objectives were met within the constraints of an uncompromising time schedule. (author)

K-shell ionisation cross sections for W, Au and U by low velocity protons

International Nuclear Information System (INIS)

Castro Faria, N.V. de; Freire Junior, F.L.; Montenegro, E.C.; Pinho, A.G. de; Silveira, E.F. da.

1984-01-01

Proton-induced K-shell ionisation cross section for W, Au and U by low velocity protons were obtained from thick target measurements. For the first time the lowest incident energy reached a value less than 10 times the binding energy of the K-shell electron (less than 9 times in the case of Au). Possible errors are thoroughly examined and a comparison with other available experimental results and theoretical values is presented and discussed. (Author) [pt

Electron-capture cross sections for low-energy highly charged neon and argon ions from molecular and atomic hydrogen

International Nuclear Information System (INIS)

Can, C.; Gray, T.J.; Varghese, S.L.; Hall, J.M.; Tunnell, L.N.

1985-01-01

Electron-capture cross sections for low-velocity (10 6 --10 7 cm/s) highly charged Ne/sup q/+ (2< or =q< or =7) and Ar/sup q/+ (2< or =q< or =10)= projectiles incident on molecular- and atomic-hydrogen targets have been measured. A recoil-ion source that used the collisions of fast heavy ions (1 MeV/amu) with target gas atoms was utilized to produce slow highly charged ions. Atomic hydrogen was produced by dissociating hydrogen molecules in a high-temperature oven. Measurements and analysis of the data for molecular- and atomic-hydrogen targets are discussed in detail. The measured absolute cross sections are compared with published data and predictions of theoretical models

Rapid analysis of formic acid, acetic acid, and furfural in pretreated wheat straw hydrolysates and ethanol in a bioethanol fermentation using atmospheric pressure chemical ionisation mass spectrometry

Directory of Open Access Journals (Sweden)

Smart Katherine A

2011-09-01

Full Text Available Abstract Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS offers advantages as a rapid analytical technique for the quantification of three biomass degradation products (acetic acid, formic acid and furfural within pretreated wheat straw hydrolysates and the analysis of ethanol during fermentation. The data we obtained using APCI-MS correlated significantly with high-performance liquid chromatography analysis whilst offering the analyst minimal sample preparation and faster sample throughput.

High resolution atomic spectra of rare earths : progress report

International Nuclear Information System (INIS)

Saksena, G.D.; Ahmad, S.A.

1976-01-01

High resolution studies of atomic spectra of neodymium and gadolinium are being carried out on a recording Fabry-Perot spectrometer. The present progress report concerns work done on new assignments as well as confirmation of recently assigned electronic configurations and evaluation of isotope shifts of energy levels which have been possible from the isotope shift data obtained for several transitions of NdI, NdII and GdI, GdII respectively. (author)

High Fidelity Simulation of Atomization in Diesel Engine Sprays

Science.gov (United States)

2015-09-01

state Figure 5. Q criterion isosurface colored by streamwise velocity in the diesel spray injector as viewed from the nozzle exit. Figure 6. U contour...fidelity simulation approach was adopted to study the atom- ization physics of a diesel injector with detailed nozzle internal geometry. The nozzle flow...26; Stanford, CA 14. ABSTRACT A high fidelity numerical simulation of jet breakup and spray formation from a complex diesel fuel injector has been

Progress of highly charged atomic physics at IMP

International Nuclear Information System (INIS)

Ma, X; Zhu, X L; Liu, H P; Li, B; Wei, B R; Sha, S; Cao, S P; Chen, L F; Zhang, S F; Feng, W T; Zhang, D C; Qian, D B

2007-01-01

The progress of atomic physics researches at the Institute of Modern Physics (IMP) is reviewed, covering the studies on ion-atom/molecule collisions, ion-cluster interaction, negative ion formation, state-selective electron capture studied by COLTRIMS, as well as the progress of a new experimental area dedicated for atomic researches at moderate energies, and the advances of the cooler storage rings at the Heavy Ion Research Facility in Lanzhou (HIRFL). New opportunities to study collision dynamics from femto-second to atto-second regime are opened based on the present facilities and the on-going projects

Risks of low dose ionising radiation exposures Riesgos derivados de la exposición a dosis bajas de radiación ionizante

Directory of Open Access Journals (Sweden)

Almudena Real Gallego

2010-12-01

Full Text Available Although ionising radiation has been shown to have several beneficial applications for humans, it can also produce detrimental effects in humans and the environment. To adequately protect man and environment from the potential harmful effects of ionising radiation, is essential to know in detail the biological effects produced by it, its characteristics and the various factors that influence these effects. That is the objective of this article, describe the current status of knowledge about biological effects induced by ionising radiation, with special emphasis on those effects occurring after low dose exposures.La radiación ionizante ha mostrado tener diversas aplicaciones beneficiosas para el hombre, pero también puede dañar la salud de las personas y el medio ambiente. Para proteger adecuadamente al hombre de los posibles efectos nocivos de la radiación ionizante es imprescindible conocer en detalle los efectos biológicos producidos por esta, sus características y los distintos factores que influyen en dichos efectos. Ese es el objetivo de este artículo: describir el estado actual del conocimiento sobre los efectos biológicos que puede producir la radiación ionizante, con especial énfasis en aquellos efectos que se producen tras la exposición a dosis bajas.

Dégradation de lŽADN par les rayonnements ionisants. Influence de la structure et de lŽenvironnement

Czech Academy of Sciences Publication Activity Database

Maurizot, M.; Běgusová, Marie

11-12 (2003), s. 97-102 ISSN 0151-9093 R&D Projects: GA AV ČR IAA1048103 Institutional research plan: CEZ:AV0Z1048901 Keywords : DNA * ionising radiations * hydroxyl radical Subject RIV: BO - Biophysics Impact factor: 0.112, year: 2003

Three-dimensional atom localization via electromagnetically induced transparency in a three-level atomic system.

Science.gov (United States)

Wang, Zhiping; Cao, Dewei; Yu, Benli

2016-05-01

We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.

Atom interferometry with trapped Bose-Einstein condensates: impact of atom-atom interactions

International Nuclear Information System (INIS)

Grond, Julian; Hohenester, Ulrich; Mazets, Igor; Schmiedmayer, Joerg

2010-01-01

Interferometry with ultracold atoms promises the possibility of ultraprecise and ultrasensitive measurements in many fields of physics, and is the basis of our most precise atomic clocks. Key to a high sensitivity is the possibility to achieve long measurement times and precise readout. Ultracold atoms can be precisely manipulated at the quantum level and can be held for very long times in traps; they would therefore be an ideal setting for interferometry. In this paper, we discuss how the nonlinearities from atom-atom interactions, on the one hand, allow us to efficiently produce squeezed states for enhanced readout and, on the other hand, result in phase diffusion that limits the phase accumulation time. We find that low-dimensional geometries are favorable, with two-dimensional (2D) settings giving the smallest contribution of phase diffusion caused by atom-atom interactions. Even for time sequences generated by optimal control, the achievable minimal detectable interaction energy ΔE min is of the order of 10 -4 μ, where μ is the chemical potential of the Bose-Einstein condensate (BEC) in the trap. From these we have to conclude that for more precise measurements with atom interferometers, more sophisticated strategies, or turning off the interaction-induced dephasing during the phase accumulation stage, will be necessary.

An atomic beam source for fast loading of a magneto-optical trap under high vacuum

DEFF Research Database (Denmark)

McDowall, P.D.; Hilliard, Andrew; Grünzweig, T.

2012-01-01

We report on a directional atomic beam created using an alkali metal dispenser and a nozzle. By applying a high current (15 A) pulse to the dispenser at room temperature we can rapidly heat it to a temperature at which it starts dispensing, avoiding the need for preheating. The atomic beam produced...... is capable of loading 90 of a magneto-optical trap (MOT) in less than 7 s while maintaining a low vacuum pressure of 10 -11 Torr. The transverse velocity components of the atomic beam are measured to be within typical capture velocities of a rubidium MOT. Finally, we show that the atomic beam can be turned...

Atomic origin of high-temperature electron trapping in metal-oxide-semiconductor devices

Energy Technology Data Exchange (ETDEWEB)

Shen, Xiao, E-mail: xiao.shen@vanderbilt.edu [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Dhar, Sarit [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States); Pantelides, Sokrates T. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2015-04-06

MOSFETs based on wide-band-gap semiconductors are suitable for operation at high temperature, at which additional atomic-scale processes that are benign at lower temperatures can get activated, resulting in device degradation. Recently, significant enhancement of electron trapping was observed under positive bias in SiC MOSFETs at temperatures higher than 150 °C. Here, we report first-principles calculations showing that the enhanced electron trapping is associated with thermally activated capturing of a second electron by an oxygen vacancy in SiO{sub 2} by which the vacancy transforms into a structure that comprises one Si dangling bond and a bond between a five-fold and a four-fold Si atoms. The results suggest a key role of oxygen vacancies and their structural reconfigurations in the reliability of high-temperature MOS devices.

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

Science.gov (United States)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

[Atomic/ionic fluorescence in microwave plasma torch discharge with excitation of high current and microsecond pulsed hollow cathode lamp: Ca atomic/ionic fluorescence spectrometry].

Science.gov (United States)

Gong, Zhen-bin; Liang, Feng; Yang, Peng-yuan; Jin, Qin-han; Huang, Ben-li

2002-02-01

A system of atomic and ionic fluorescence spectrometry in microwave plasma torch (MPT) discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL) has been developed. The operation conditions for Ca atomic and ionic fluorescence spectrometry have been optimized. Compared with atomic fluorescence spectrometry (AFS) in argon microwave induced plasma (MIP) and MPT with the excitation of direct current and conventional pulsed HCL, the system with HCMP HCL excitation can improve AFS and ionic fluorescence spectrometry (IFS) detection limits in MPT atomizer and ionizer. Detection limits (3 sigma) with HCMP HCL-MPT-AFS/IFS are 10.1 ng.mL-1 for Ca I 422.7 nm, 14.6 ng.mL-1 for Ca II 393.4 nm, and 37.4 ng.mL-1 for Ca II 396.8 nm, respectively.

Bond formation in hafnium atom implantation into SiC induced by high-energy electron irradiation

International Nuclear Information System (INIS)

Yasuda, H.; Mori, H.; Sakata, T.; Naka, M.; Fujita, H.

1992-01-01

Bilayer films of Hf (target atoms)/α-SiC (substrate) were irradiated with 2 MeV electrons in an ultra-high voltage electron microscope (UHVEM), with the electron beam incident on the hafnium layer. As a result of the irradiation, hafnium atoms were implanted into the SiC substrate. Changes in the microstructure and valence electronic states associated with the implantation were studied by a combination of UHVEM and Auger valence electron spectroscopy. The implantation process is summarized as follows. (1) Irradiation with 2 MeV electrons first induces a crystalline-to-amorphous transition in α-SiC. (2) Hafnium atoms which have been knocked-off from the hafnium layer by collision with the 2 MeV electrons are implanted into the resultant amorphous SiC. (3) The implanted hafnium atoms make preferential bonding to carbon atoms. (4) With continued irradiation, the hafnium atoms repeat the displacement along the beam direction and the subsequent bonding with the dangling hybrids of carbon and silicon. The repetition of the displacement and subsequent bonding lead to the deep implantation of hafnium atoms into the SiC substrate. It is concluded that implantation successfully occurs when the bond strength between a constituent atom of a substrate and an injected atom is stronger than that between constituent atoms of a substrate. (Author)

Construction of high-dimensional neural network potentials using environment-dependent atom pairs.