LHC Report: Ions cross protons

CERN Multimedia

Reyes Alemany Fernandez for the LHC team

2013-01-01

The LHC starts the New Year facing a new challenge: proton-lead collisions in the last month before the shutdown in mid-February.    The first stable beams were achieved on 20 January with 13 individual bunches per beam. In the next fill, the first bunch-trains were injected and stable beams were achieved with 96 proton on 120 ion bunches.  This fill was very important because we were able to study the so-called moving long-range beam-beam encounters. Long-range encounters, which are also seen in proton-proton runs, occur when the bunches in the two beams “see” each other as they travel in the same vacuum chamber at either side of the experiments.  The situation becomes more complicated with proton-lead ions because the two species have different revolution times (until the frequencies are locked at top energy- see “Cogging exercises”) and thus these encounters move. We found that this effect does not cause significant beam losses...

Chemical equilibration in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Brown, Gerald E.; Lee, Chang-Hwan; Rho, Mannque

2005-01-01

In the hadronic sector of relativistic heavy ion physics, the ρ<-2π reaction is the strongest one, strong enough to equilibrate the ρ with the pions throughout the region from chemical freezeout to thermal freezeout when free-particle interactions (with no medium-dependent effects) are employed. Above the chiral restoration temperature, only ρ's and π's are present, in that the chirally restored A1 is equivalent to the ρ and the mesons have an SU(4) symmetry, with no dependence on isospin and negligible dependence on spin. In the same sense the σ and π are 'equivalent' scalars. Thus the chirally restored ρ<-2π exhaust the interspecies transitions. We evaluate this reaction at Tc and find it to be much larger than below Tc, certainly strong enough to equilibrate the chirally restored mesons just above Tc. When emitted just below Tc the mesons remain in the Tc+ε freezeout distribution, at least in the chiral limit because of the Harada-Yamawaki 'vector manifestation' that requires that mesonic coupling constants go to zero (in the chiral limit) as T goes to Tc from below. Our estimates in the chiral limit give deviations in some particle ratios from the standard scenario (of equilibrium in the hadronic sector just below Tc) of about double those indicated experimentally. This may be due to the neglect of explicit chiral symmetry breaking in our estimates. We also show that the instanton molecules present above Tc are the giant multipole vibrations found by Asakawa, Hatsuda and Nakahara and of Wetzorke et al. in lattice gauge calculations. Thus, the matter formed by RHIC can equivalently be called: chirally restored mesons, instanton molecules, or giant collective vibrations. It is a strongly interacting liquid

High intensity negative proton beams from a SNICS ion source

International Nuclear Information System (INIS)

Evans, C.R.; Hollander, M.G.

1991-01-01

For the past year we have been involved in a project to develop an intense (> 100μA) negative proton beam from a SNICS (Source of Negative Ions by Cesium Sputtering) ion source. This report will cover how we accomplished and exceeded this goal by more than 40%. Included in these observations will be the following: A description of an effective method for making titanium hydride cathodes. How to overcome the limitations of the titanium hydride cathode. The modification of the SNICS source to improve output; including the installation of the conical ionizer and the gas cathode. A discussion of problems including: poisoning the proton beam with oxygen, alternative gas cathode materials, the clogging of the gas inlet, long burn-in times, and limited cathode life times. Finally, how to optimize source performance when using a gas cathode, and what is the mechanism by which a gas cathode operates; facts, fantasies, or myth

A new ion exchange behavior of protonated titanate nanotubes after deprotonation and the study on their morphology and optical properties

International Nuclear Information System (INIS)

Zhang Huibin; Cao Lixin; Liu Wei; Su Ge

2012-01-01

Graphical abstract: The morphological transformation of protonated titanate nanotubes under alkali solution before ion exchange (a) and after ion exchange (b). Highlights: ► A novel ion exchange behavior of protonated titanate nanotubes after deprotonation. ► The exchangeability of protonated titanate nanotubes are not as inert as past reported. ► The tube walls of H 2 Ti 3 O 7 nanotubes is observed to get loosened after ion exchange. ► The paper proves a new and easy way to modify protonated titanate nanotubes. - Abstract: After the deprotonation of protonated titanate nanotubes (H 2 Ti 3 O 7 ), we observed a novel ion exchange behavior on them. In the past literatures, protonated titanate nanotubes prepared via hydrothermal method have been reported with a poor exchangeability which may due to the chemical bonding of interlayer protons to nearby oxygen atoms. However, in this experiment under alkali environment (pH > 10), protonated titanate nanotubes exhibited a vast ion exchange capacity toward [Co(NH 3 ) 6 ] 2+ . This interesting phenomenon is contrary to the past reports which found protonated titanate nanotubes hardly could be ionexchanged by objective cations. This paper proves the deprotonation process on H 2 Ti 3 O 7 nanotubes sufficiently facilitates the diffusion of metal complex cations into protonated titanate nanotubes and significantly changes their ion exchange capacity. As a consequence of cabalt intercalting via ion exchange, the tube wall of H 2 Ti 3 O 7 nanotubes is observed to get loosened. Additionally, the exciton concentrations corresponding to the nanotube surface states are discussed in the paper.

submitter Next generation multi-scale biophysical characterization of high precision cancer particle radiotherapy using clinical proton, helium-, carbon- and oxygen ion beams

CERN Document Server

Dokic, Ivana; Niklas, Martin; Zimmermann, Ferdinand; Chaudhri, Naved; Krunic, Damir; Tessonnier, Thomas; Ferrari, Alfredo; Parodi, Katia; Jäkel, Oliver; Debus, Jürgen; Haberer, Thomas; Abdollahi, Amir

2016-01-01

The growing number of particle therapy facilities worldwide landmarks a novel era of precision oncology. Implementation of robust biophysical readouts is urgently needed to assess the efficacy of different radiation qualities. This is the first report on biophysical evaluation of Monte Carlo simulated predictive models of prescribed dose for four particle qualities i.e., proton, helium-, carbon- or oxygen ions using raster-scanning technology and clinical therapy settings at HIT. A high level of agreement was found between the in silico simulations, the physical dosimetry and the clonogenic tumor cell survival. The cell fluorescence ion track hybrid detector (Cell-Fit-HD) technology was employed to detect particle traverse per cell nucleus. Across a panel of radiobiological surrogates studied such as late ROS accumulation and apoptosis (caspase 3/7 activation), the relative biological effectiveness (RBE) chiefly correlated with the radiation species-specific spatio-temporal pattern of DNA double strand break ...

Recommended data on proton-ion collision rate coefficients for Fe X-Fe XV ions

International Nuclear Information System (INIS)

Skobelev, I.; Murakami, I.; Kato, T.

2006-01-01

The proton-ion collisions are important for excitation of some ion levels in a high-temperature low density plasma. In the present work evaluation of data obtained for proton-induced transitions in Fe X - Fe XV ions with the help of different theoretical methods is carried out. It is suggested a simple analytical formula with 7 parameters allowing to describe dependency of proton rate coefficient on proton temperature in an enough wide temperature range. The values of free parameters have been determined by fitting of approximation formula to numerical data and are presented for recommended data together with fitting accuracies. By comparing of proton collision rates with electron ones it is shown that proton impact excitation processes may be important for Fe X, XI, XIII-XV ions. The results obtained can be used for plasma kinetics calculations and for development of spectroscopy methods of plasma diagnostics. (author)

Proton-ion collisions: behind the scenes of an exotic interaction

CERN Multimedia

Antonella Del Rosso

2012-01-01

Protons to the right, ions to the left: the basic principle of proton-ion collisions at the LHC might seem straightforward. However, this is an almost unprecedented mode of collider operation, certainly unique at the energy provided by the LHC. In addition to being a remarkable technical achievement, this interaction between a proton and an ion can potentially contribute a lot to the understanding of the properties of matter in its primordial state.   Prior to last week, the LHC had only collided protons with protons and lead ions with lead ions. These were indeed the two operational schemes the LHC was designed for. However, since science can often evolve in directions that were not necessarily expected at the beginning of a project, over the years the scientific community has become more and more interested in the hybrid type of interaction – that between protons and ions. Last week’s collisions were only a test for the teams involved in the operation of the LHC, in prepara...

Thermodynamic analysis of direct internal reforming of methane and butane in proton and oxygen conducting fuel cells

NARCIS (Netherlands)

Biesheuvel, P.M.; Geerlings, J.J.C.

2008-01-01

We present results of a thermodynamic analysis of direct internal reforming fuel cells, based on either a proton conducting fuel cell (FC-H+) or an oxygen ion conducting fuel cell (FC-O2-). We analyze the option of methane as fuel as well as butane. The model self-consistently combines all chemical

Tumour control in ion beam radiotherapy with different ions in the presence of hypoxia: an oxygen enhancement ratio model based on the microdosimetric kinetic model

Science.gov (United States)

Strigari, L.; Torriani, F.; Manganaro, L.; Inaniwa, T.; Dalmasso, F.; Cirio, R.; Attili, A.

2018-03-01

Few attempts have been made to include the oxygen enhancement ratio (OER) in treatment planning for ion beam therapy, and systematic studies to evaluate the impact of hypoxia in treatment with the beam of different ion species are sorely needed. The radiobiological models used to quantify the OER in such studies are mainly based on the dose-averaged LET estimates, and do not explicitly distinguish between the ion species and fractionation schemes. In this study, a new type of OER modelling, based on the microdosimetric kinetic model, taking into account the specificity of the different ions, LET spectra, tissues and fractionation schemes, has been developed. The model has been benchmarked with published in vitro data, HSG, V79 and CHO cells in aerobic and hypoxic conditions, for different ion irradiation. The model has been included in the simulation of treatments for a clinical case (brain tumour) using proton, lithium, helium, carbon and oxygen ion beams. A study of the tumour control probability (TCP) as a function of oxygen partial pressure, dose per fraction and primary ion type has been performed. The modelled OER depends on both the LET and ion type, also showing a decrease for an increased dose per fraction with a slope that depends on the LET and ion type, in good agreement with the experimental data. In the investigated clinical case, a significant increase in TCP has been found upon increasing the ion charge. Higher OER variations as a function of dose per fraction have also been found for low-LET ions (up to 15% varying from 2 to 8 Gy(RBE) for protons). This model could be exploited in the identification of treatment condition optimality in the presence of hypoxia, including fractionation and primary particle selection.

Weak and strong coupling equilibration in nonabelian gauge theories

Energy Technology Data Exchange (ETDEWEB)

Keegan, Liam [Physics Department, Theory Unit, CERN,CH-1211 Genève 23 (Switzerland); Kurkela, Aleksi [Physics Department, Theory Unit, CERN,CH-1211 Genève 23 (Switzerland); Faculty of Science and Technology, University of Stavanger,4036 Stavanger (Norway); Romatschke, Paul [Department of Physics, 390 UCB, University of Colorado at Boulder,Boulder, CO (United States); Center for Theory of Quantum Matter, University of Colorado,Boulder, Colorado 80309 (United States); Schee, Wilke van der [Center for Theoretical Physics, MIT,Cambridge, MA 02139 (United States); Zhu, Yan [Department of Physics, University of Jyväskyla, P.O. Box 35, FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics,P.O. Box 64, 00014 University of Helsinki (Finland)

2016-04-06

We present a direct comparison studying equilibration through kinetic theory at weak coupling and through holography at strong coupling in the same set-up. The set-up starts with a homogeneous thermal state, which then smoothly transitions through an out-of-equilibrium phase to an expanding system undergoing boost-invariant flow. This first apples-to-apples comparison of equilibration provides a benchmark for similar equilibration processes in heavy-ion collisions, where the equilibration mechanism is still under debate. We find that results at weak and strong coupling can be smoothly connected by simple, empirical power-laws for the viscosity, equilibration time and entropy production of the system.

Weak and strong coupling equilibration in nonabelian gauge theories

International Nuclear Information System (INIS)

Keegan, Liam; Kurkela, Aleksi; Romatschke, Paul; Schee, Wilke van der; Zhu, Yan

2016-01-01

We present a direct comparison studying equilibration through kinetic theory at weak coupling and through holography at strong coupling in the same set-up. The set-up starts with a homogeneous thermal state, which then smoothly transitions through an out-of-equilibrium phase to an expanding system undergoing boost-invariant flow. This first apples-to-apples comparison of equilibration provides a benchmark for similar equilibration processes in heavy-ion collisions, where the equilibration mechanism is still under debate. We find that results at weak and strong coupling can be smoothly connected by simple, empirical power-laws for the viscosity, equilibration time and entropy production of the system.

Protons on ions bring new physics to LHCb

CERN Multimedia

Antonella Del Rosso

2013-01-01

The research opportunities offered by proton-lead collisions at the LHC are generating increasing interest among theorists and experimentalists. During this recent run, LHCb, the asymmetric detector originally designed to study CP asymmetries and rare decays involving heavy quarks, took data with proton and ion beams for the first time. Using these collisions, the experiment can provide a different perspective on specific physics processes, so new developments may be in sight.   A proton-lead ion collision observed by the LHCb detector during the 2013 data taking period. LHCb is a smaller detector than the gigantic multi-purpose CMS and ATLAS detectors. It is also smaller than ALICE, the detector designed in particular to study ion-ion collisions. However, LHCb has something special: it can study physics processes that involve particles scattered from collisions at very small angles and close to the collision point. LHCb does not take data during ion-ion r...

Chemical and kinetic equilibrations via radiative parton transport

International Nuclear Information System (INIS)

Zhang Bin; Wortman, Warner A

2011-01-01

A hot and dense partonic system can be produced in the early stage of a relativistic heavy ion collision. How it equilibrates is important for the extraction of Quark-Gluon Plasma properties. We study the chemical and kinetic equilibrations of the Quark-Gluon Plasma using a radiative transport model. Thermal and Color-Glass-Condensate motivated initial conditions are used. We observe that screened parton interactions always lead to partial pressure isotropization. Different initial pressure anisotropies result in the same asymptotic evolution. Comparison of evolutions with and without radiative processes shows that chemical equilibration interacts with kinetic equilibration and radiative processes can contribute significantly to pressure isotropization.

Intermediate energy proton and light-ion scattering

International Nuclear Information System (INIS)

Moss, J.M.

1981-01-01

A review is presented of recent (1979-81) developments in the field of intermediate-energy proton and light-ion scattering from nuclei. New theoretical and calculational techniques of particular interest to experimentalists are discussed. Emphasis is placed on topics in nuclear structure physics - giant resonances, pion-condensation precursor phenomena, and polarization transfer (spin-flip) experiments - where intermediate energy proton and light-ion scattering has made new and unique contributions

Reactions of atomic oxygen with the chlorate ion and the perchlorate ion

Science.gov (United States)

Anan'ev, Vladimir; Miklin, Mikhail; Kriger, Ludmila

2014-06-01

The reactions of the chlorate ion with atomic oxygen formed under photolysis of the nitrate ion introduced to potassium chlorate crystal by co-crystallization were studied by optical and infrared absorption spectroscopy. The perchlorate ion was found to form in solids as product of addition reaction of singlet atomic oxygen, formed under dissociation of the peroxynitrite ion - the product of isomerization of the excited nitrate ion. Triplet atomic oxygen does not react with the chlorate ion. The atomic oxygen formed under photolysis of the nitrate ion introduced to potassium perchlorate crystal by co-crystallization does not react with the perchlorate ion.

An evolutionarily conserved gene family encodes proton-selective ion channels.

Science.gov (United States)

Tu, Yu-Hsiang; Cooper, Alexander J; Teng, Bochuan; Chang, Rui B; Artiga, Daniel J; Turner, Heather N; Mulhall, Eric M; Ye, Wenlei; Smith, Andrew D; Liman, Emily R

2018-03-02

Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, Otop2 and Otop3 , and a Drosophila ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Inter- and intra-annular proton exchange in gaseous benzylbenzenium ions (protonated diphenylmethane)

OpenAIRE

Kuck, Dietmar; Bäther, Wolfgang

1986-01-01

Two distinct proton exchange reactions occur in metastable gaseous benzylbenzenium ions, generated by isobutane chemical ionization of diphenylmethane and four deuterium-labelled analogues. Whereas the proton ring-walk at the benzenium moiety is fast giving rise to a completely random intraannular proton exchange, the interannular proton exchange is surprisingly slow and competes with the elimination of benzene. A kinetic isotope effect of kH/kD= 5 has been determined for the interannular pro...

Mixed oxygen ion/electron-conducting ceramics for oxygen separation

Energy Technology Data Exchange (ETDEWEB)

Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)

1996-08-01

Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

Emission of positive oxygen ions from ion bombardment of adsorbate-covered metal surfaces

International Nuclear Information System (INIS)

Kaurin, M.G.

1989-01-01

During ion bombardment of metal surfaces, collision cascades can result in the emission of sputtered secondary ions. Recent experiments, however, have suggested that the emission of positive ions of electronegative adsorbates can result from electronic processes rather than from processes involving elastic collisions. This dissertation presents the results of experiments studying the emission of positive oxygen ions from oxygen- and carbon-monoxide-covered transition metal surfaces during bombardment by 25-250 keV ions of neon, argon, and krypton. The systems studied may be grouped into four categories. For a nickel substrate with adsorbed oxygen, the emission of positive oxygen ions proceeds through collision cascades. For titanium and niobium with adsorbed oxygen, the emission of positive oxygen ions is proportional to the primary ion velocity, consistent with emission from electronic processes; for a given primary ion velocity, the oxygen ion yield is independent of primary ion species. For substrates of molybdenum and tungsten, the oxygen yield is proportional to primary ion velocity, but the yield also depends on the primary ion species for a given primary ion velocity in a manner that is consistent with emission resulting from electronic processes. For these two groups, except for titanium, the yields during neon ion bombardment do not extrapolate (assuming linearity with primary ion velocity) to a nonzero value at zero beam velocity. The magnitude of the oxygen ion yields from these targets is not consistent with that expected if the emission were induced by secondary electrons emitted during the ion bombardment

Proton capture and loss in ion-molecule collisions

International Nuclear Information System (INIS)

Ibanez, S; Alessi, M; Zimmerman, V; Fregenal, D; Focke, P; Bernardi, G; Suarez, S

2007-01-01

We have measured proton distributions from the collision systems Ar + , Kr + on CH 4 molecular targets, searching for atom capture into the projectile continuum. Within the studied energy range (100 to 300 eV/u) we have not distinctive evidence of capture. A small contamination of ion beams with molecular ions as ArH + or KrH + , have shown to be enough to produce peak shaped structures at the projectile velocity. We, therefore, concentrate our study on proton loss from molecular ions in collision with several targets

Effects of electron-ion temperature equilibration on inertial confinement fusion implosions.

Science.gov (United States)

Xu, Barry; Hu, S X

2011-07-01

The electron-ion temperature relaxation essentially affects both the laser absorption in coronal plasmas and the hot-spot formation in inertial confinement fusion (ICF). It has recently been reexamined for plasma conditions closely relevant to ICF implosions using either classical molecular-dynamics simulations or analytical methods. To explore the electron-ion temperature equilibration effects on ICF implosion performance, we have examined two Coulomb logarithm models by implementing them into our hydrocodes, and we have carried out hydrosimulations for ICF implosions. Compared to the Lee-More model that is currently used in our standard hydrocodes, the two models predict substantial differences in laser absorption, coronal temperatures, and neutron yields for ICF implosions at the OMEGA Laser Facility [Boehly et al. Opt. Commun. 133, 495 (1997)]. Such effects on the triple-picket direct-drive design at the National Ignition Facility (NIF) have also been explored. Based on the validity of the two models, we have proposed a combined model of the electron-ion temperature-relaxation rate for the overall ICF plasma conditions. The hydrosimulations using the combined model for OMEGA implosions have shown ∼6% more laser absorption, ∼6%-15% higher coronal temperatures, and ∼10% more neutron yield, when compared to the Lee-More model prediction. It is also noticed that the gain for the NIF direct-drive design can be varied by ∼10% among the different electron-ion temperature-relaxation models.

Chemical equilibration due to heavy Hagedorn states

International Nuclear Information System (INIS)

Greiner, C; Koch-Steinheimer, P; Liu, F M; Shovkovy, I A; Stoecker, H

2005-01-01

A scenario of heavy resonances, called massive Hagedorn states, is proposed which exhibits a fast (t ∼ 1 fm/c) chemical equilibration of (strange) baryons and anti-baryons at the QCD critical temperature T c . For relativistic heavy ion collisions this scenario predicts that hadronization is followed by a brief expansion phase during which the equilibration rate is higher than the expansion rate, so that baryons and antibaryons reach chemical equilibrium before chemical freeze-out occurs

Proton and Ion Sources for High Intensity Accelerators

CERN Multimedia

Scrivens, R

2004-01-01

Future high intensity ion accelerators, including the Spallation Neutron Source (SNS), the European Spallation Source (ESS), the Superconducting Proton Linac (SPL) etc, will require high current and high duty factor sources for protons and negative hydrogen ions. In order to achieve these goals, a comparison of the Electron Cyclotron Resonance, radio-frequency and Penning ion sources, among others, will be made. For each of these source types, the present operational sources will be compared to the state-of-the-art research devices with special attention given to reliability and availability. Finally, the future research and development aims will be discussed.

Proton RBS measurement of the oxygen in heavy-metal oxides

International Nuclear Information System (INIS)

Xie, T.; Ryan, S.R.; Fischbeck, H.J.

1989-01-01

Although the stoichoimetry of high-T c superconductors is often measured using alpha-particle RBS, the small Rutherford cross section for oxygen relative to the high-Z components makes a determination of the oxygen content difficult. Above 1 MeV, the cross section for proton backscattering from oxygen becomes significantly greater than the Rutherford cross section. Studies of proton backscattering in CuO between 0.6 and 2.0 MeV show that it is possible to measure the oxygen content of high-Z metal oxides. RBS simulations using the Bragg-rule stopping power consistently underestimate the low-energy yield. Scaling the stopping power by a linear function of energy to reduce loss at low energy improves the simulation in CuO, Cu and Au. This general result suggests that the standard RBS simulation procedure may omit some relevant physics. (orig.)

Heavy ion and proton-induced single event multiple upset

International Nuclear Information System (INIS)

Reed, R.A.; Carts, M.A.; Marshall, P.W.

1997-01-01

Individual ionizing heavy ion events are shown to cause two or more adjacent memory cells to change logic states in a high density CMOS SRAM. A majority of the upsets produced by normally incident heavy ions are due to single-particle events that causes a single cell to upset. However, for grazing angles a majority of the upsets produced by heavy-ion irradiation are due to single-particle events that cause two or more cells to change logic states. Experimental evidence of a single proton-induced spallation reaction that causes two adjacent memory cells to change logic states is presented. Results from a dual volume Monte-Carlo simulation code for proton-induced single-event multiple upsets are within a factor of three of experimental data for protons at normal incidence and 70 degrees

Ion measurements in premixed methane-oxygen flames

KAUST Repository

Alquaity, Awad

2014-07-25

Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

Reactive oxygen species-based measurement of the dependence of the Coulomb nanoradiator effect on proton energy and atomic Z value.

Science.gov (United States)

Seo, Seung-Jun; Jeon, Jae-Kun; Han, Sung-Mi; Kim, Jong-Ki

2017-11-01

The Coulomb nanoradiator (CNR) effect produces the dose enhancement effects from high-Z nanoparticles under irradiation with a high-energy ion beam. To gain insight into the radiation dose and biological significance of the CNR effect, the enhancement of reactive oxygen species (ROS) production from iron oxide or gold NPs (IONs or AuNPs, respectively) in water was investigated using traversing proton beams. The dependence of nanoradiator-enhanced ROS production on the atomic Z value and proton energy was investigated. Two biologically important ROS species were measured using fluorescent probes specific to •OH or [Formula: see text] in a series of water phantoms containing either AuNPs or IONs under irradiation with a 45- or 100-MeV proton beam. The enhanced generation of hydroxyl radicals (•OH) and superoxide anions ([Formula: see text]) was determined to be caused by the dependence on the NP concentration and proton energy. The proton-induced Au or iron oxide nanoradiators exhibited different ROS enhancement rates depending on the proton energy, suggesting that the CNR radiation varied. The curve of the superoxide anion production from the Au-nanoradiator showed strong non-linearity, unlike the linear behavior observed for hydroxyl radical production and the X-ray photoelectric nanoradiator. In addition, the 45-MeV proton-induced Au nanoradiator exhibited an ROS enhancement ratio of 8.54/1.50 ([Formula: see text] / •OH), similar to that of the 100-KeV X-ray photoelectric Au nanoradiator (7.68/1.46). The ROS-based detection of the CNR effect revealed its dependence on the proton beam energy, dose and atomic Z value and provided insight into the low-linear energy transfer (LET) CNR radiation, suggesting that these factors may influence the therapeutic efficacy via chemical reactivities, transport behaviors, and intracellular oxidative stress.

Distribution of energetic oxygen and hydrogen in the near-Earth plasma sheet

Science.gov (United States)

Kronberg, E. A.; Grigorenko, E. E.; Haaland, S. E.; Daly, P. W.; Delcourt, D. C.; Luo, H.; Kistler, L. M.; Dandouras, I.

2015-05-01

The spatial distributions of different ion species are useful indicators for plasma sheet dynamics. In this statistical study based on 7 years of Cluster observations, we establish the spatial distributions of oxygen ions and protons at energies from 274 to 955 keV, depending on geomagnetic and solar wind (SW) conditions. Compared with protons, the distribution of energetic oxygen has stronger dawn-dusk asymmetry in response to changes in the geomagnetic activity. When the interplanetary magnetic field (IMF) is directed southward, the oxygen ions show significant acceleration in the tail plasma sheet. Changes in the SW dynamic pressure (Pdyn) affect the oxygen and proton intensities in the same way. The energetic protons show significant intensity increases at the near-Earth duskside during disturbed geomagnetic conditions, enhanced SW Pdyn, and southward IMF, implying there location of effective inductive acceleration mechanisms and a strong duskward drift due to the increase of the magnetic field gradient in the near-Earth tail. Higher losses of energetic ions are observed in the dayside plasma sheet under disturbed geomagnetic conditions and enhanced SW Pdyn. These observations are in agreement with theoretical models.

Free energy for protonation reaction in lithium-ion battery cathode materials

International Nuclear Information System (INIS)

Benedek, R.; Thackeray, M. M.; van de Walle, A.

2008-01-01

Calculations are performed of free energies for proton-for-lithium-ion exchange reactions in lithium-ion battery cathode materials. First-principles calculations are employed for the solid phases and tabulated ionization potential and hydration energy data for aqueous ions. Layered structures, spinel LiMn 2 O 4 , and olivine LiFePO 4 are considered. Protonation is most favorable energetically in layered systems, such as Li 2 MnO 3 and LiCoO 2 . Less favorable are ion-exchange in spinel LiMn 2 O 4 and LiV 3 O 8 . Unfavorable is the substitution of protons for Li in olivine LiFePO 4 , because of the large distortion of the Fe and P coordination polyhedra. The reaction free energy scales roughly linearly with the volume change in the reaction

Antimatter production in proton-proton and heavy-ion collisions at ultrarelativistic energies

International Nuclear Information System (INIS)

Cleymans, J.; Kabana, S.; Kraus, I.; Oeschler, H.; Redlich, K.; Sharma, N.

2011-01-01

One of the striking features of particle production at high beam energies is the near-equal abundance of matter and antimatter in the central rapidity region. In this paper we study how this symmetry is reached as the beam energy is increased. In particular, we quantify explicitly the energy dependence of the approach to matter-antimatter symmetry in proton-proton and in heavy-ion collisions. Expectations are presented also for the production of more complex forms of antimatter such as antihypernuclei.

Thermomechanical response of Large Hadron Collider collimators to proton and ion beam impacts

Directory of Open Access Journals (Sweden)

Marija Cauchi

2015-04-01

Full Text Available The CERN Large Hadron Collider (LHC is designed to accelerate and bring into collision high-energy protons as well as heavy ions. Accidents involving direct beam impacts on collimators can happen in both cases. The LHC collimation system is designed to handle the demanding requirements of high-intensity proton beams. Although proton beams have 100 times higher beam power than the nominal LHC lead ion beams, specific problems might arise in case of ion losses due to different particle-collimator interaction mechanisms when compared to protons. This paper investigates and compares direct ion and proton beam impacts on collimators, in particular tertiary collimators (TCTs, made of the tungsten heavy alloy INERMET® 180. Recent measurements of the mechanical behavior of this alloy under static and dynamic loading conditions at different temperatures have been done and used for realistic estimates of the collimator response to beam impact. Using these new measurements, a numerical finite element method (FEM approach is presented in this paper. Sequential fast-transient thermostructural analyses are performed in the elastic-plastic domain in order to evaluate and compare the thermomechanical response of TCTs in case of critical beam load cases involving proton and heavy ion beam impacts.

An atomic oxygen device based on PIG oxygen negative ion source

International Nuclear Information System (INIS)

Yu Jinxiang; Cai Minghui; Han Jianwei

2008-01-01

It is an important research subject for the spaceflight countries to conduct equivalent simulation of 5 eV atomic oxygen effects for the spaceflight material in low earth orbit. This paper introduces an apparatus used for producing atomic oxygen, which consists of a PIG ion source with permanent magnet, two electrodes extraction system, an electron deflector, an einzel lens, an ion decelerating electrode and a sample bracket. At present it has been used on the small debris accelerator in the Center for Space Science and Applied Research, Chinese Academy of Sciences, and the producing experiments of O - are carried out. 200-300μA of O - ions are extracted at the extraction voltage of 2-3 kV. The experiments for decelerating of O - ions and erosion of kapton foil are carried out also. Because of the target room used for both the atomic oxygen device and the small debris accelerator, the facility can be used for small debris impinging and atomic erosion for spaceflight materials simultaneously. (authors)

The Generation of Dehydroalanine Residues in Protonated Polypeptides: Ion/Ion Reactions for Introducing Selective Cleavages

Science.gov (United States)

Peng, Zhou; Bu, Jiexun; McLuckey, Scott A.

2017-09-01

We examine a gas-phase approach for converting a subset of amino acid residues in polypeptide cations to dehydroalanine (Dha). Subsequent activation of the modified polypeptide ions gives rise to specific cleavage N-terminal to the Dha residue. This process allows for the incorporation of selective cleavages in the structural characterization of polypeptide ions. An ion/ion reaction within the mass spectrometer between a multiply protonated polypeptide and the sulfate radical anion introduces a radical site into the multiply protonated polypeptide reactant. Subsequent collisional activation of the polypeptide radical cation gives rise to radical side chain loss from one of several particular amino acid side chains (e.g., leucine, asparagine, lysine, glutamine, and glutamic acid) to yield a Dha residue. The Dha residues facilitate preferential backbone cleavages to produce signature c- and z-ions, demonstrated with cations derived from melittin, mechano growth factor (MGF), and ubiquitin. The efficiencies for radical side chain loss and for subsequent generation of specific c- and z-ions have been examined as functions of precursor ion charge state and activation conditions using cations of ubiquitin as a model for a small protein. It is noted that these efficiencies are not strongly dependent on ion trap collisional activation conditions but are sensitive to precursor ion charge state. Moderate to low charge states show the greatest overall yields for the specific Dha cleavages, whereas small molecule losses (e.g., water/ammonia) dominate at the lowest charge states and proton catalyzed amide bond cleavages that give rise to b- and y-ions tend to dominate at high charge states. [Figure not available: see fulltext.

Thermal ion-molecule reactions in oxygen-containing molecules

International Nuclear Information System (INIS)

Kumakura, Minoru

1981-02-01

The energetics of ions and the thermal ion-molecule reactions in oxygen-containing molecules have been studied with a modified time-of-flight mass spectrometer. It was found that the translational energy of ion can be easily obtained from analysis of the decay curve using the time-of-flight mass spectrometer. The condensation-elimination reactions proceeded via cross- and homo-elimination mechanism in which the nature of intermediate-complex could be correlated with the nature of reactant ion. It was elucidated that behavior of poly-atomic oxygen-containing ions on the condensation-elimination reactions is considerably influenced by their oxonium ion structures having functional groups. In addition, the rate constants of the condensation-elimination reactions have affected with the energy state of reactant ion and the dipole moment and/or the polarizability of neutral molecule. It was clarified that the rate constants of the ion-molecule clustering reactions in poly-atomic oxygen-containing molecules such as cyclic ether of six member rings are very large and the cluster ions are stable owing to the large number of vibrational degree of freedom in the cluster ions. (author)

Radiation Environment Model of Protons and Heavier Ions at Jupiter

Science.gov (United States)

Sierra, Luz Maria Martinez; Garrett, Henry B.; Jun, Insoo

2015-01-01

We performed an in depth study of the methods used to review the geometric factors (GF) and sensitivity to charge particles of the Energetic Particle Detector instrument on board the Galileo Spacecraft. Monte Carlo simulations were performed to understand the interactions of electrons and ions (i. e., protons and alphas) with the sensitive regions of the instrument. The DC0 and B0 channels were studied with the intention of using them to update the jovian proton radiation model. The results proved that the B0 is a clean proton chanel without any concerns for contamination by heavier ions and electrons. In contrast, DC0 was found to be contaminated by electrons. Furthermore, we also found out that the B2 channel is a clean alpha particle channel (in other words, no contamination by electrons and/or protons).

Experimental control of the beam properties of laser-accelerated protons and carbon ions

Energy Technology Data Exchange (ETDEWEB)

Amin, Munib

2008-12-15

The laser generation of energetic high quality beams of protons and heavier ions has opened up the door to a plethora of applications. These beams are usually generated by the interaction of a short pulse high power laser with a thin metal foil target. They could already be applied to probe transient phenomena in plasmas and to produce warm dense matter by isochoric heating. Other applications such as the production of radioisotopes and tumour radiotherapy need further research to be put into practice. To meet the requirements of each application, the properties of the laser-accelerated particle beams have to be controlled precisely. In this thesis, experimental means to control the beam properties of laser-accelerated protons and carbon ions are investigated. The production and control of proton and carbon ion beams is studied using advanced ion source designs: Experiments concerning mass-limited (i.e. small and isolated) targets are conducted. These targets have the potential to increase both the number and the energy of laser-accelerated protons. Therefore, the influence of the size of a plane foil target on proton beam properties is measured. Furthermore, carbon ion sources are investigated. Carbon ions are of particular interest in the production of warm dense matter and in cancer radiotherapy. The possibility to focus carbon ion beams is investigated and a simple method for the production of quasi-monoenergetic carbon ion beams is presented. This thesis also provides an insight into the physical processes connected to the production and the control of laser-accelerated ions. For this purpose, laser-accelerated protons are employed to probe plasma phenomena on laser-irradiated targets. Electric fields evolving on the surface of laser-irradiated metal foils and hollow metal foil cylinders are investigated. Since these fields can be used to displace, collimate or focus proton beams, understanding their temporal and spatial evolution is crucial for the design of

Experimental control of the beam properties of laser-accelerated protons and carbon ions

International Nuclear Information System (INIS)

Amin, Munib

2008-12-01

The laser generation of energetic high quality beams of protons and heavier ions has opened up the door to a plethora of applications. These beams are usually generated by the interaction of a short pulse high power laser with a thin metal foil target. They could already be applied to probe transient phenomena in plasmas and to produce warm dense matter by isochoric heating. Other applications such as the production of radioisotopes and tumour radiotherapy need further research to be put into practice. To meet the requirements of each application, the properties of the laser-accelerated particle beams have to be controlled precisely. In this thesis, experimental means to control the beam properties of laser-accelerated protons and carbon ions are investigated. The production and control of proton and carbon ion beams is studied using advanced ion source designs: Experiments concerning mass-limited (i.e. small and isolated) targets are conducted. These targets have the potential to increase both the number and the energy of laser-accelerated protons. Therefore, the influence of the size of a plane foil target on proton beam properties is measured. Furthermore, carbon ion sources are investigated. Carbon ions are of particular interest in the production of warm dense matter and in cancer radiotherapy. The possibility to focus carbon ion beams is investigated and a simple method for the production of quasi-monoenergetic carbon ion beams is presented. This thesis also provides an insight into the physical processes connected to the production and the control of laser-accelerated ions. For this purpose, laser-accelerated protons are employed to probe plasma phenomena on laser-irradiated targets. Electric fields evolving on the surface of laser-irradiated metal foils and hollow metal foil cylinders are investigated. Since these fields can be used to displace, collimate or focus proton beams, understanding their temporal and spatial evolution is crucial for the design of

Progress in the production of intense ion beams and the formation of proton layers

International Nuclear Information System (INIS)

Kapetanakos, C.A.; Golden, J.; Marsh, S.J.; Mahaffey, R.A.

1977-01-01

The results on ion sources and the application of ion beams to the formation of proton layers and rings are presented. Ion beams have been produced on three different generators. Some results from the experiments performed on the Gamble 2 generator are presented. The Gamble 2 generator with coaxial anode-cathode configuration, hollow beam cross-section produces power levels of 0.6-1.2 MV with peak ion current of 200 kA. The number of protons in the beam 4x10 16 . Peak ion currents is excess 200 kA, energy 1 MeV, ion current density 1 kA/cm 2 . Magnetic field configuration to provide formation of strong proton layers is shown

Biological intercomparison using gut crypt survivals for proton and carbon ions

International Nuclear Information System (INIS)

Uzawa, Akiko; Ando, Koichi; Furusawa, Yoshiya

2006-01-01

Charged particle therapy depends on biological information for the dose prescription. Relative biological effectiveness or relative biological effectiveness (RBE) for this requirement could basically be provided by experimental data. As RBE values of protons and carbon ions depend on several factors such as cell/tissue type, endpoint, dose and fractionation schedule, a single RBE value could not function as a master key to open all rooms filled with guests of different radiosensitivities. However, any biological model with accurate reproducibility is useful for comparing biological effectiveness between different facilities. We used mouse gut crypt survivals as endpoint, and compared the cell killing efficiency of proton beams at three Japanese facilities. Three Linac X-ray machines with 4 and 6 MeV were used as reference beams, and there was only a small variation (coefficient of variance <2%) in biological effectiveness among them. The RBE values of protons relative to Linac X-rays ranged from 1.0 to 1.11 at the middle of a 6-cm SOBP (spread-out Bragg peak) and from 0.96 to 1.01 at the entrance plateau. The coefficient of variance for protons ranged between 4.0 and 5.1%. The biological comparison of carbon ions showed fairly good agreement in that the difference in biological effectiveness between National Institute of Radiological Sciences (NIRS)/Heavy Ion Medical Accelerator in Chiba (HIMAC) and Gesellschaft fur Schwerionenforschung (GSI)/Heavy Ion Synchrotron (SIS) was 1% for three positions within the 6-cm SOBP. The coefficient of variance was <1.7, <0.6 and <1.6% for proximal, middle and distal SOBP, respectively. We conclude that the inter-institutional variation of biological effectiveness is smaller for carbon ions than protons, and that beam-spreading methods of carbon ions do not critically influence gut crypt survival. (author)

Molecular Ions in Ion Upflows and their Effects on Hot Atomic Oxygen Production

Science.gov (United States)

Foss, V.; Yau, A. W.; Shizgal, B.

2017-12-01

We present new direct ion composition observations of molecular ions in auroral ion upflows from the CASSIOPE Enhanced Polar Outflow Probe (e-POP). These observed molecular ions are N2+, NO+, and possibly O2+, and are found to occur at all e-POP altitudes starting at about 400 km, during auroral substorms and the different phases of magnetic storms, sometimes with upflow velocities exceeding a few hundred meters per second and abundances of 5-10%. The dissociative recombination of both O2+ and NO+ was previously proposed as an important source of hot oxygen atoms in the topside thermosphere [Hickey et al., 1995]. We investigate the possible effect of the observed molecular ions on the production of hot oxygen atoms in the storm and substorm-time auroral thermosphere. We present numerical solutions of the Boltzmann equation for the steady-state oxygen energy distribution function, taking into account both the production of the hot atoms and their subsequent collisional relaxation. Our result suggests the formation of a hot oxygen population with a characteristic temperature on the order of 0.3 eV and constituting 1-5% of the oxygen density near the exobase. We discuss the implication of this result in the context of magnetosphere-ionosphere-thermosphere coupling.

Chemical equilibration of antihyperons

International Nuclear Information System (INIS)

Greiner, C.

2002-01-01

Rapid chemical equilibration of antihyperons by means of the interplay between strong annihilation on baryons and the corresponding backreactions of multi-mesonic (fusion-type) processes in the later, hadronic stage of an ultrarelativistic heavy ion collision will be discussed. Explicit rate calculations for a dynamical setup are presented. At maximum SPS energies yields of each antihyperon specie are obtained which are consistent with chemical saturated populations of T∼150-160 MeV. The proposed picture supports dynamically the popular chemical freeze-out parameters extracted within thermal models. (orig.)

Proton concentrations can be a major contributor to the modification of osteoclast and osteoblast differentiation, working independently of extracellular bicarbonate ions.

Science.gov (United States)

Kato, Kohtaro; Matsushita, Misao

2014-01-01

We established a system to separately analyze the role of protons and bicarbonate ions in vitro in which the pH of the medium was controlled by HEPES at various concentrations of sodium bicarbonate (NaHCO3) in the absence of carbon dioxide (CO2). Using this system, we demonstrated that acidosis promoted osteoclast formation independently of extracellular NaHCO3 in a short-term culture. Protons and bicarbonate ions acted on osteoclast differentiation with opposite effects, the former positively and the latter negatively. The HEPES-based system maintained pH in the absence of extracellular NaHCO3 without CO2. Therefore, we could demonstrate that osteoblast differentiation was promoted at higher pH in a long-term culture system without NaHCO3 in which ALP activity and nodule mineralization were enhanced. This finding indicates that protons negatively control osteoblast differentiation independently of extracellular bicarbonate ions. However, the difference in the concentration of NaHCO3 did not have any influence on nodule mineralization. The opposite effects of protons, the promotion of osteoclast formation and the inhibition of osteoblast differentiation, were suppressed in the presence of 5 mM N-acetyl cysteine, a reagent activating the scavenging of reactive oxygen species (ROS), implying that ROS act on both systems, the promotion of large osteoclast formation and the deterioration of osteoblast formation under acidosis.

Direct Comparison of Biologically Optimized Spread-out Bragg Peaks for Protons and Carbon Ions

International Nuclear Information System (INIS)

Wilkens, Jan J.; Oelfke, Uwe

2008-01-01

Purpose: In radiotherapy with hadrons, it is anticipated that carbon ions are superior to protons, mainly because of their biological properties: the relative biological effectiveness (RBE) for carbon ions is supposedly higher in the target than in the surrounding normal tissue, leading to a therapeutic advantage over protons. The purpose of this report is to investigate this effect by using biological model calculations. Methods and Materials: We compared spread-out Bragg peaks for protons and carbon ions by using physical and biological optimization. The RBE for protons and carbon ions was calculated according to published biological models. These models predict increased RBE values in regions of high linear energy transfer (LET) and an inverse dependency of the RBE on dose. Results: For pure physical optimization, protons yield a better dose distribution along the central axis. In biologically optimized plans, RBE variations for protons were relatively small. For carbon ions, high RBE values were found in the high-LET target region, as well as in the low-dose region outside the target. This means that the LET dependency and dose dependency of the RBE can cancel each other. We show this for radioresistant tissues treated with two opposing beams, for which the predicted carbon RBE within the target volume was lower than outside. Conclusions: For tissue parameters used in this study, the model used does not predict a biologic advantage of carbon ions. More reliable model parameters and clinical trials are necessary to explore the true potential of radiotherapy with carbon ions

Proton transfer and complex formation of angiotensin I ions with gaseous molecules at various temperature

International Nuclear Information System (INIS)

Nonose, Shinji; Yamashita, Kazuki; Sudo, Ayako; Kawashima, Minami

2013-01-01

Highlights: • Proton transfer from angiotensin I ions (z = 2, 3) to gaseous molecules was studied. • Temperature dependence of absolute reaction rate constants was measured. • Remarkable changes were obtained for distribution of product ions and reaction rate constants. • Proton transfer reaction was enhanced and reduced by complex formation. • Conformation changes are induced by complex formation and or by thermal collision with He. - Abstract: Proton transfer reactions of angiotensin I ions for +2 charge state, [M + 2H] 2+ , to primary, secondary and aromatic amines were examined in the gas phase. Absolute reaction rate constants for proton transfer were determined from intensities of parent and product ions in the mass spectra. Temperature dependence of the reaction rate constants was measured. Remarkable change was observed for distribution of product ions and reaction rate constants. Proton transfer reaction was enhanced or reduced by complex formation of [M + 2H] 2+ with gaseous molecules. The results relate to conformation changes of [M + 2H] 2+ with change of temperature, which are induced by complex formation and or by thermal collision with He. Proton transfer reactions of angiotensin I ions for +3 charge state, [M + 3H] 3+ , were also studied. The reaction rates did not depend on temperature so definitely

Ceramic membrane fuel cells based on solid proton electrolytes

Energy Technology Data Exchange (ETDEWEB)

Meng, Guangyao; Ma, Qianli; Peng, Ranran; Liu, Xingqin [USTC Lab. for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Ma, Guilin [School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123 (China)

2007-04-15

The development of solid oxide fuel cells (SOFCs) has reached its new stage characterized with thin electrolytes on porous electrode support, and the most important fabrication techniques developed in which almost all are concerned with inorganic membranes, and so can be named as ceramic membrane fuel cells (CMFCs). CMFCs based on proton electrolytes (CMFC-H) may exhibit more advantages than CMFCs based on oxygen-ion electrolytes (CMFC-O) in many respects, such as energy efficiency and avoiding carbon deposit. Ammonia fuelled CMFC with proton-conducting BaCe{sub 0.8}Gd{sub 0.2}O{sub 2.9} (BCGO) electrolyte (50 {mu}m in thickness) is reported in this works, which showed the open current voltage (OCV) values close to theoretical ones and rather high power density. And also, we have found that the well known super oxide ion conductor, La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{alpha}} (LSGM), is a pure proton conductor in H{sub 2} and mixed proton and oxide ion conductor in wet air, while it is a pure oxide ion conductor in oxygen or dry air. To demonstrate the CMFC-H concept to get high performance fuel cells the techniques for thin membranes, chemical vapor deposition (CVD), particularly novel CVD techniques, should be given more attention because of their many advantages. (author)

ABSORPTIONS IN THE VISIBLE OF PROTONATED PYRENE COLLISIONALLY COOLED TO 15 K

Energy Technology Data Exchange (ETDEWEB)

Hardy, F.-X.; Gause, O.; Rice, C. A.; Maier, J. P., E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstr. 80, 4056-CH Basel (Switzerland)

2013-12-01

Protonated polycyclic hydrocarbons have been added to the list of suggested carriers of diffuse interstellar absorptions. To test this proposition requires laboratory spectra measured under interstellar conditions, in particular with the rotational and vibrational degrees of freedom equilibrated to low temperatures. This has been achieved for protonated pyrene with absorption bands in the visible, using an ion trap and collisional cooling to ≈15 K. A two-photon excitation-dissociation scheme was employed to record the (1) {sup 1} A' ← X {sup 1} A' electronic spectrum on around 10{sup 5} ions per duty cycle. The origin band of the absorption spectrum of this relatively large polycyclic aromatic species with 27 atoms is located at 4858.86 Å. Two further comparably intense spectral features are present at 4834.48 and 4809.32 Å. This is one of the largest protonated aromatics studied in the gas phase and compared to astronomical observations; however, it is not a carrier of known diffuse interstellar bands.

Mechanisms behind the generation of protonated ions for polyaromatic hydrocarbons by atmospheric pressure photoionization.

Science.gov (United States)

Ahmed, Arif; Choi, Cheol Ho; Choi, Myoung Choul; Kim, Sunghwan

2012-01-17

In this study, the mechanism behind the generation of protonated polyaromatic hydrocarbon (PAH) ions without heteroatoms by atmospheric pressure photoionization (APPI) is investigated. Comparing data obtained by APPI of anthracene dissolved either in toluene or perdeuterated toluene suggests that toluene acts as a source of protons and that breakage of C-H bonds in the toluene molecule is important for the overall protonation reaction. Our data describing an Arrhenius-type temperature-dependent relationship between the signal intensities of molecular and protonated ions suggest a mechanistic relation between the generated molecular and protonated ions. The APPI protonation mechanism that best explains the observed phenomena is composed of two reactions: electron transfer followed by hydrogen transfer. This two-step mechanism for APPI was originally suggested by Syage (Syage, J. A. J. Am. Soc. Mass Spectrom. 2004, 15 , 1521-1533). Further quantum mechanical study shows that an energetically favorable ion-molecular complex can be generated as a result of electron transfer from toluene to PAH, which subsequently facilitates hydrogen transfer. This suggests that both electron transfer and hydrogen transfer can occur as a "concerted" reaction through the ion-molecular complex precursor state, which is consistent with experimental results. To our best knowledge, this is the first time that the dynamic nature of the APPI process is clearly revealed by combined experimental and quantum mechanical studies.

Feasibility of using laser ion accelerators in proton therapy

CERN Document Server

Bulanov, S V

2002-01-01

The feasibility of using the laser plasma as a source of the high-energy ions for the proton radiation therapy is discussed. The proposal is based on the recent inventions of the effective ions acceleration in the experiments and through numerical modeling of the powerful laser radiation interaction with the gaseous and solid state targets. The principal peculiarity of the dependence of the protons energy losses in the tissues (the Bragg peak of losses) facilities the solution of one of the most important problems of the radiation therapy, which consists in realizing the tumor irradiation by sufficiently high and homogeneous dose with simultaneous minimization of the irradiation level, relative to the healthy and neighbouring tissues and organs

Preliminary Comparison of the Response of LHC Tertiary Collimators to Proton and Ion Beam Impacts

CERN Document Server

Cauchi, M; Bertarelli, A; Carra, F; Cerutti, F; Lari, L; Mollicone, P; Sammut, N

2013-01-01

The CERN Large Hadron Collider is designed to bring into collision protons as well as heavy ions. Accidents involving impacts on collimators can happen for both species. The interaction of lead ions with matter differs to that of protons, thus making this scenario a new interesting case to study as it can result in different damage aspects on the collimator. This paper will present a preliminary comparison of the response of collimators to proton and ion beam impacts.

Ion measurements in premixed methane-oxygen flames

KAUST Repository

Alquaity, Awad; Hourani, Nadim; Chahine, May; Selim, Hatem; Sarathy, Mani; Farooq, Aamir

2014-01-01

Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry

Biological intercomparison using gut crypt survivals for proton and carbon-ion beams

International Nuclear Information System (INIS)

Uzawa, Akiko; Ando, Koichi; Furusawa, Yoshiya

2007-01-01

Charged particle therapy depends on biological information for the dose prescription. Relative biological effectiveness or RBE for this requirement could basically be provided by experimental data. As RBE values of protons and carbon ions depend on several factors such as cell/tissue type, biological endpoint, dose and fractionation schedule, a single RBE value could not deal with all different radiosensitivities. However, any biological model with accurate reproducibility is useful for comparing biological effectiveness between different facilities. We used mouse gut crypt survivals as endpoint, and compared the cell killing efficiency of proton beams at three Japanese facilities. Three Linac X-ray machines with 4 and 6 MeV were used as reference beams, and there was only a small variation (coefficient of variance<2%) in biological effectiveness among them. The RBE values of protons relative to Linac X-rays ranged from 1.0 to 1.11 at the middle of a 6-cm SOBP (spread-out Bragg peak) and from 0.96 to 1.01 at the entrance plateau. The coefficient of variance for protons ranged between 4.0 and 5.1%. The biological comparison of carbon ions showed fairly good agreement in that the difference in biological effectiveness between National Institute of Radiological Sciences (NIRS)/ Heavy Ion Medical Accelerator in Chiba (HIMAC) and Gesellschaft fur Schwerionenforschung (GSI)/Heavy Ion Synchrotron (SIS) was 1% for three positions within the 6-cm SOBP. The coefficient of variance was <1.7, <0.6 and <1.6% for proximal, middle and distal SOBP, respectively. We conclude that the inter-institutional variation of biological effectiveness is smaller for carbon ions than protons, and that beam-spreading methods of carbon ions do not critically influence gut crypt survival. (author)

TH-A-19A-05: Modeling Physics Properties and Biologic Effects Induced by Proton and Helium Ions

Energy Technology Data Exchange (ETDEWEB)

Taleei, R; Titt, U; Peeler, C; Guan, F; Mirkovic, D; Grosshans, D; Mohan, R [UT MD Anderson Cancer Center, Houston, TX (United States)

2014-06-15

Purpose: Currently, proton and carbon ions are used for cancer treatment. More recently, other light ions including helium ions have shown interesting physical and biological properties. The purpose of this work is to study the biological and physical properties of helium ions (He-3) in comparison to protons. Methods: Monte Carlo simulations with FLUKA, GEANT4 and MCNPX were used to calculate proton and He-3 dose distributions in water phantoms. The energy spectra of proton and He-3 beams were calculated with high resolution for use in biological models. The repair-misrepairfixation (RMF) model was subsequently used to calculate the RBE. Results: The proton Bragg curve calculations show good agreement between the three general purpose Monte Carlo codes. In contrast, the He-3 Bragg curve calculations show disagreement (for the magnitude of the Bragg peak) between FLUKA and the other two Monte Carlo codes. The differences in the magnitude of the Bragg peak are mainly due to the discrepancy in the secondary fragmentation cross sections used by the codes. The RBE for V79 cell lines is about 0.96 and 0.98 at the entrance of proton and He-3 ions depth dose respectively. The RBE increases to 1.06 and 1.59 at the Bragg peak of proton and He-3 ions. The results demonstrated that LET, microdosimetric parameters (such as dose-mean lineal energy) and RBE are nearly constant along the plateau region of Bragg curve, while all parameters increase within the Bragg peak and at the distal edge for both proton and He-3 ions. Conclusion: The Monte Carlo codes should revise the fragmentation cross sections to more accurately simulate the physical properties of He-3 ions. The increase in RBE for He-3 ions is higher than for proton beams at the Bragg peak.

Structural change of NaO1/2-WO3-NbO5/2-LaO3/2-PO5/2 glass induced by electrochemical substitution of sodium ions with protons.

Science.gov (United States)

Ishiyama, Tomohiro; Yamaguchi, Takuya; Nishii, Junji; Yamashita, Toshiharu; Kawazoe, Hiroshi; Kuwata, Naoaki; Kawamura, Junichi; Omata, Takahisa

2015-05-28

Structural changes of 35NaO1/2-1WO3-8NbO5/2-5LaO3/2-51PO5/2 glass (1W-glass) before and after the electrochemical substitution of sodium ions with protons by alkali-proton substitution (APS) are studied by Raman and (31)P magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies. The glass before APS consists of (PO3(-))8.6(P2O7(4-)) chains on average and the terminal Q(1) units (-O-PO3(3-)) are bound to MO6 octahedra (M denotes niobium or tungsten) through P-O-M bonds. Some non-bridging oxygens (NBOs) in the MO6 octahedra are present in addition to the bridging oxygens (BOs) in P-O-M bonds. APS induces fragmentation of the phosphate chains because the average chain length decreases to (PO3(-))3.7(P2O7(4-)) after APS, despite the total number of modifier cations of sodium and lanthanum ions and protons being unaffected by APS. This fragmentation is induced by some of the NBOs in the MO6 octahedra before APS, changing to BOs of the newly formed M-O-P bonds after APS, because of the preferential formation of P-OH bonds over M-OH ones in the present glass. We show that APS under the conditions used here is not a simple substitution of sodium ions with protons, but it is accompanied by the structural relaxation of the glass to stabilize the injected protons.

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

Science.gov (United States)

Sittler, E. C., Jr.; Ali, A.; Cooper, J. F.; Hartle, R. E.; Johnson, R. E.; Coates, A. J.; Young, D. T.

2009-01-01

Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process

Speculations on the existence of hydride ions in proton conducting oxides

DEFF Research Database (Denmark)

Poulsen, F.W.

2001-01-01

The chemical and physical nature of the hydride ion is briefly treated. Several reactions of the hydride ion in oxides or oxygen atmosphere are given, A number of perovskites and inverse perovskites are listed. which contain the H- ion on the oxygen or B-anion sites in the archetype ABO(3) System...

Spot size dependence of laser accelerated protons in thin multi-ion foils

International Nuclear Information System (INIS)

Liu, Tung-Chang; Shao, Xi; Liu, Chuan-Sheng; Eliasson, Bengt; Wang, Jyhpyng; Chen, Shih-Hung

2014-01-01

We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80 MeV quasi-monoenergetic proton beam containing more than 10 8 protons using a laser beam with power 250 TW and energy 10 J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen

Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation.

Science.gov (United States)

Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

2013-09-07

The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from (12)C (4.44 MeV) and (16)O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 10(7) oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from (16)O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring (16)O PG emission.

Determination of equilibration kinetics of oxide electrode materials using a manometric method

International Nuclear Information System (INIS)

Badwal, S.P.S.; Jiang, S.P.; Love, J.; Nowotny, J.; Rekas, M.

1998-01-01

The gas/solid equilibration kinetics for electrode oxide materials, such as (La 0.8 Sr 0.2 )MnO 3 , using a manometric method, was determined. The reaction kinetics between oxygen and the oxide material was monitored using the measurements of the P(O 2 ) changes during isothermic experiments of oxidation and reduction. The procedure of the determination will be described and relevant kinetic equations was derived. The equilibration kinetic data obtained can be used to determine the chemical diffusion coefficient. Copyright (1998) Australasian Ceramic Society

High intensity proton injector for facility of antiproton and ion research

Energy Technology Data Exchange (ETDEWEB)

Berezov, R., E-mail: r.berezov@gsi.de; Brodhage, R.; Fils, J.; Hollinger, R.; Ivanova, V. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Chauvin, N.; Delferriere, O.; Tuske, O. [Commissariat à l’Energie Atomique et aux Energies Alternatives, IRFU, F-91191 Gif-sur-Yvette (France); Ullmann, C. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Institut für Angewandte Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany)

2016-02-15

The high current ion source with the low energy beam transport (LEBT) will serve as injector into the proton LINAC to provide primary proton beam for the production of antiprotons. The pulsed ion source developed and built in CEA/Saclay operates with a frequency of 2.45 GHz based on ECR plasma production with two coils with 87.5 mT magnetic field necessary for the electron cyclotron resonance. The compact LEBT consists of two solenoids with a maximum magnetic field of 500 mT including two integrated magnetic steerers to adjust the horizontal and vertical beam positions. The total length of the compact LEBT is 2.3 m and was made as short as possible to reduced emittance growth along the beam line. To measure ion beam intensity behind the pentode extraction system, between solenoids and at the end of the beam line, two current transformers and a Faraday cup are installed. To get information about the beam quality and position, the diagnostic chamber with different equipment will be installed between the two solenoids. This article reports the current status of the proton injector for the facility of antiproton and ion research.

Activation of acid-sensing ion channels by localized proton transient reveals their role in proton signaling.

Science.gov (United States)

Zeng, Wei-Zheng; Liu, Di-Shi; Liu, Lu; She, Liang; Wu, Long-Jun; Xu, Tian-Le

2015-09-15

Extracellular transients of pH alterations likely mediate signal transduction in the nervous system. Neuronal acid-sensing ion channels (ASICs) act as sensors for extracellular protons, but the mechanism underlying ASIC activation remains largely unknown. Here, we show that, following activation of a light-activated proton pump, Archaerhodopsin-3 (Arch), proton transients induced ASIC currents in both neurons and HEK293T cells co-expressing ASIC1a channels. Using chimera proteins that bridge Arch and ASIC1a by a glycine/serine linker, we found that successful coupling occurred within 15 nm distance. Furthermore, two-cell sniffer patch recording revealed that regulated release of protons through either Arch or voltage-gated proton channel Hv1 activated neighbouring cells expressing ASIC1a channels. Finally, computational modelling predicted the peak proton concentration at the intercellular interface to be at pH 6.7, which is acidic enough to activate ASICs in vivo. Our results highlight the pathophysiological role of proton signalling in the nervous system.

90 deg.Neutron emission from high energy protons and lead ions on a thin lead target

CERN Document Server

Agosteo, S; Foglio-Para, A; Mitaroff, W A; Silari, Marco; Ulrici, L

2002-01-01

The neutron emission from a relatively thin lead target bombarded by beams of high energy protons/pions and lead ions was measured at CERN in one of the secondary beam lines of the Super Proton Synchrotron for radiation protection and shielding calculations. Measurements were performed with three different beams: sup 2 sup 0 sup 8 Pb sup 8 sup 2 sup + lead ions at 40 GeV/c per nucleon and 158 GeV/c per nucleon, and 40 GeV/c mixed protons/pions. The neutron yield and spectral fluence per incident ion on target were measured at 90 deg.with respect to beam direction. Monte-Carlo simulations with the FLUKA code were performed for the case of protons and pions and the results found in good agreement with the experimental data. A comparison between simulations and experiment for protons, pions and lead ions have shown that--for such high energy heavy ion beams--a reasonable estimate can be carried out by scaling the result of a Monte-Carlo calculation for protons by the projectile mass number to the power of 0.80-0...

Modification of WS2 nanosheets with controllable layers via oxygen ion irradiation

Science.gov (United States)

Song, Honglian; Yu, Xiaofei; Chen, Ming; Qiao, Mei; Wang, Tiejun; Zhang, Jing; Liu, Yong; Liu, Peng; Wang, Xuelin

2018-05-01

As one kind of two-dimensional materials, WS2 nanosheets have drawn much attention with different kinds of research methods. Yet ion irradiation method was barely used for WS2 nanosheets. In this paper, the structure, composition and optical band gap (Eg) of the multilayer WS2 films deposited by chemical vapor deposition (CVD) method on sapphire substrates before and after oxygen ion irradiation with different energy and fluences were studied. Precise tailored layer-structures and a controllable optical band gap of WS2 nanosheets were achieved after oxygen ion irradiation. The results shows higher energy oxygen irradiation changed the shape from triangular shaped grains to irregular rectangle shape but did not change 2H-WS2 phase structure. The intensity of E2g1 (Г) and A1g (Г) modes decreased and have small shifts after oxygen ion irradiation. The peak frequency difference between the E2g1 (Г) and A1g (Г) modes (Δω) decreased after oxygen ion irradiation, and this result indicates the number of layers decreased after oxygen ion irradiation. The Eg decreased with the increase of the energy and the fluence of oxygen ions. The number of layers, thickness and optical band gap changed after ion irradiation with different ion fluences and energies. The results proposed a new strategy for precise control of multilayer nanosheets and demonstrated the high applicability of ion irradiation in super-capacitors, field effect transistors and other applications.

Mutation breeding of rape by using proton ion beam

International Nuclear Information System (INIS)

Eun, J. S.; Chang, Y. S.; Han, S. G.; Choi, S. R.; Kim, J. S.

2006-04-01

This experiment was carried out by irradiation the proton ion beam and gamma-ray at level 100 to 2,000 Gy on dry seeds of 3 varieties, 'Naehan', 'Hanla' and 'Tammi' to increase the cultivation area and develope for biodiesel in rape (Brassica napus) and checked the radiosensitivity test including germination rate, emergence rate and chromosome aberration and the occurrence of morphological mutant in M1 generation. The germination rate and emergence rate were 98∼100% because they had no relation with radiation source, dosage and variety. There was no significance in survival rate up to 1,000 Gy dosage after sowing of 7 days and remarkably reduced from 39.5 to 69.6% at 1,500 to 2,000 Gy dosage. The length and area of cotyledon, and hypocotyl length were highly reduced with significance by increasing dosage of proton ion and gamma-irradiation in all 3 varieties and showed the sensitive responses on 'Naehan', 'Hanla' and 'Tammi' in order. By the way, there was a radiation hormesis in 'Tammi' by increasing the length and area of cotyledon in the proton ion treatment at 100∼200 Gy dosage compared to the control (no treatment). With the same effect, it had the similar results in the fresh weight of above-aerial parts in 3∼4 weeks after sowing

Proton conductive Pt-Co nanoparticles anchoring on citric acid functionalized graphene for efficient oxygen reduction reaction

Science.gov (United States)

Zhao, Yige; Liu, Jingjun; Wu, Yijun; Wang, Feng

2017-08-01

Designing highly efficient electro-catalysts for the oxygen reduction reaction (ORR) has been regarded as a demanding task in the development of renewable energy sources. However, little attention has been paid on improving Pt-based catalysts by promoting proton transfer from the electrolyte solutions to the catalyst layer at the cathode. Herein, we design proton conductive Pt-Co alloy nanoparticles anchoring on citric acid functionalized graphene (Pt-Co/CA-G) catalysts for efficient ORR. The facile modification approach for graphene can introduce oxygenated functional groups on the graphene surface to promote proton transfer as well as keeping the high electron conductivity without destroying the graphene original structure. The electrochemical results show that the Pt-Co/CA-G catalyst exhibits more excellent ORR activity and stability than the commercial Pt/C catalyst, which can be attributed to its improved proton transfer ability. The fast proton transfer comes from the hydrogen-bonding networks formed by the interaction between the oxygenated functional groups and water molecules. This work provides not only a novel and simple approach to modify graphene but also an effective strategy to improve Pt-based catalysts for the ORR.

Comparison of proton and phosphorous ion implantation-induced intermixing of InAs/InP quantum dots

Energy Technology Data Exchange (ETDEWEB)

Barik, S; Tan, H H; Jagadish, C [Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

2007-05-02

We report and compare proton and phosphorous ion implantation-induced intermixing of InAs/InP quantum dots (QDs). After ion implantation at 20-300 deg. C, the QDs are rapid thermally annealed at 850 deg. C for 30 s. Proton implantation induces less energy shift than P ion implantation for a given concentration of atomic displacements due to the more efficient dynamic annealing of the defects created by protons. The implantation-induced energy shift reaches a maximum value of about 260 meV for a dose of 5 x 10{sup 12} ions cm{sup -2} in the P ion implanted QDs, which also show narrower PL linewidths compared to the proton implanted QDs. We also report the effects of an InGaAs top cap layer on the ion implantation-induced QD intermixing and show that defect production and annihilation processes evolve differently in InGaAs and InP layers and vary with the implantation temperature. When the implantation is performed at higher temperatures, the energy shift of the P ion implanted QDs capped with an InP layer increases due to the reduction in larger defect cluster formation at higher temperatures, while the energy shift of the proton implanted QDs decreases due to increased dynamic annealing irrespective of their cap layers.

Recommendation for a injector-cyclotron and ion sources for the acceleration of heavy ions and polarized protons and deuterons

International Nuclear Information System (INIS)

Botha, A.H.; Cronje, P.M.; Du Toit, Z.B.; Nel, W.A.G.; Celliers, P.J.

1984-01-01

It was decided to accelerate both heavy and light ions with the open-sector cyclotron. The injector SPS1, was used for light ions and SPS2 for heavy ions. Provision was also made for the acceleration of polarized neutrons. To enable this, the injector must have an axial injection system. The working of a source of polarized ions and inflectors for an axial injection system is discussed. The limitations of the open-sector cyclotron on the acceleration of heavy ions are also dealt with. The following acceleration/ion source combinations are discussed: i) The open-sector cyclotron and a k=40 injector cyclotron with a Penning ion source, and a stripper between the injector and the open-sector cyclotron and also a source of polarized protons and deuterons; ii) The acceleration/ion source combination with the addition of electron beam ion sources; iii) The open-sector cyclotron and a k=11 injector cyclotron with a electron beam ion source and a source of polarized protons and deuterons

Production of an accelerated oxygen-14 beam

CERN Document Server

Powell, J; Cerny, J

2003-01-01

BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 sup 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has bee...

Prospects for studies of ground-state proton decays with the Holifield Radioactive Ion Beam Facility

International Nuclear Information System (INIS)

Toth, K.S.

1994-01-01

By using radioactive ions from the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory it should be possible to identify many new ground-state proton emitters in the mass region from Sn to Pb. During this production and search process the limits of stability on the proton-rich side of the nuclidic chart will be delineated for a significant fraction of medium-weight elements and our understanding of the proton-emission process will be expanded and improved

Equivalence of displacement radiation damage in superluminescent diodes induced by protons and heavy ions

Energy Technology Data Exchange (ETDEWEB)

Li, Xingji, E-mail: lxj0218@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liu, Chaoming [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Lan, Mujie; Xiao, Liyi [Center of Micro-electronics, Harbin Institute of Technology, Harbin 150001 (China); Liu, Jianchun; Ding, Dongfa [Beijing Aerospace Times Optical-electronic Technology Co.Ltd, Beijing 100854 (China); Yang, Dezhuang; He, Shiyu [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2013-07-11

The degradation of optical power for superluminescent diodes is in situ measured under exposures of protons with various energies (170 keV, 3 MeV and 5 MeV), and 25 MeV carbon ions for several irradiation fluences. Experimental results show that the optical power of the SLDs decreases with increasing fluence. The protons with lower energies cause more degradation in the optical power of SLDs than those with higher energies at a given fluence. Compared to the proton irradiation with various energies, the 25 MeV carbon ions induce more severe degradation to the optical power. To characterize the radiation damage of the SLDs, the displacement doses as a function of chip depth in the SLDs are calculated by SRIM code for the protons and carbon ions. Based on the irradiation testing and calculation results, an approach is given to normalize the equivalence of displacement damage induced by various charged particles in SLDs.

Production of an accelerated oxygen-14 beam

International Nuclear Information System (INIS)

Powell, J.; O'Neil, J.P.; Cerny, Joseph

2003-01-01

BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has been built and is operational, and initial tests of accelerating an oxygen-14 beam have been performed

Interphase Evolution of a Lithium-Ion/Oxygen Battery.

Science.gov (United States)

Elia, Giuseppe Antonio; Bresser, Dominic; Reiter, Jakub; Oberhumer, Philipp; Sun, Yang-Kook; Scrosati, Bruno; Passerini, Stefano; Hassoun, Jusef

2015-10-14

A novel lithium-ion/oxygen battery employing Pyr14TFSI-LiTFSI as the electrolyte and nanostructured LixSn-C as the anode is reported. The remarkable energy content of the oxygen cathode, the replacement of the lithium metal anode by a nanostructured stable lithium-alloying composite, and the concomitant use of nonflammable ionic liquid-based electrolyte result in a new and intrinsically safer energy storage system. The lithium-ion/oxygen battery delivers a stable capacity of 500 mAh g(-1) at a working voltage of 2.4 V with a low charge-discharge polarization. However, further characterization of this new system by electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy reveals the progressive decrease of the battery working voltage, because of the crossover of oxygen through the electrolyte and its direct reaction with the LixSn-C anode.

Lack of conventional oxygen-linked proton and anion binding sites does not impair allosteric regulation of oxygen binding in dwarf caiman hemoglobin

Science.gov (United States)

Fago, Angela; Malte, Hans; Storz, Jay F.; Gorr, Thomas A.

2013-01-01

In contrast to other vertebrate hemoglobins (Hbs) whose high intrinsic O2 affinities are reduced by red cell allosteric effectors (mainly protons, CO2, organic phosphates, and chloride ions), crocodilian Hbs exhibit low sensitivity to organic phosphates and high sensitivity to bicarbonate (HCO3−), which is believed to augment Hb-O2 unloading during diving and postprandial alkaline tides when blood HCO3− levels and metabolic rates increase. Examination of α- and β-globin amino acid sequences of dwarf caiman (Paleosuchus palpebrosus) revealed a unique combination of substitutions at key effector binding sites compared with other vertebrate and crocodilian Hbs: β82Lys→Gln, β143His→Val, and β146His→Tyr. These substitutions delete positive charges and, along with other distinctive changes in residue charge and polarity, may be expected to disrupt allosteric regulation of Hb-O2 affinity. Strikingly, however, P. palpebrosus Hb shows a strong Bohr effect, and marked deoxygenation-linked binding of organic phosphates (ATP and DPG) and CO2 as carbamate (contrasting with HCO3− binding in other crocodilians). Unlike other Hbs, it polymerizes to large complexes in the oxygenated state. The highly unusual properties of P. palpebrosus Hb align with a high content of His residues (potential sites for oxygenation-linked proton binding) and distinctive surface Cys residues that may form intermolecular disulfide bridges upon polymerization. On the basis of its singular properties, P. palpebrosus Hb provides a unique opportunity for studies on structure-function coupling and the evolution of compensatory mechanisms for maintaining tissue O2 delivery in Hbs that lack conventional effector-binding residues. PMID:23720132

Cross sections for pion, proton, and heavy-ion production from 800 MeV protons incident upon aluminum and silicon

Energy Technology Data Exchange (ETDEWEB)

Dicello, J.F. (Clarkson Univ., Potsdam, NY (USA)); Schillaci, M.E.; Liu Lonchang (Los Alamos National Lab., NM (USA))

1990-01-01

When high-energy cosmic rays interact with electronics or other materials in a spacecraft, including the occupants themselves, pions are produced as secondary particles. These secondary pions interact further in the materials producing nuclear secondaries, including nuclear recoils and heavy-ion tertiaries. The secondary pions and the the tertiary particles are capable of producing single-event upsets and other damage in integrated circuits and damage in biological systems. Negative pions stopping in materials are particularly effective because of their unique ability to produce short-range heavy particles from pion stars. With the Los Alamos National Laboratory's version of the intranuclear cascade evaporation code, VEGAS, we have calculated the number of pions produced per energy interval per incident proton from 800 MeV protons on aluminum-27 and silicon-28 along with corresponding results for neutrons, protons, and heavier ions. (orig.).

Atomic oxygen ions as ionospheric biomarkers on exoplanets

Science.gov (United States)

Mendillo, Michael; Withers, Paul; Dalba, Paul A.

2018-04-01

The ionized form of atomic oxygen (O+) is the dominant ion species at the altitude of maximum electron density in only one of the many ionospheres in our Solar System — Earth's. This ionospheric composition would not be present if oxygenic photosynthesis was not an ongoing mechanism that continuously impacts the terrestrial atmosphere. We propose that dominance of ionospheric composition by O+ ions at the altitude of maximum electron density can be used to identify a planet in orbit around a solar-type star where global-scale biological activity is present. There is no absolute numerical value required for this suggestion of an atmospheric plasma biomarker — only the dominating presence of O+ ions at the altitude of peak electron density.

The GOES-16 Energetic Heavy Ion Instrument Proton and Helium Fluxes for Space Weather Applications

Science.gov (United States)

Connell, J. J.; Lopate, C.

2017-12-01

The Energetic Heavy Ion Sensor (EHIS) was built by the University of New Hampshire, subcontracted to Assurance Technology Corporation, as part of the Space Environmental In-Situ Suite (SEISS) on the new GOES-16 satellite, in geostationary Earth orbit. The EHIS measures energetic ions in space over the range 10-200 MeV for protons, and energy ranges for heavy ions corresponding to the same stopping range. Though an operational satellite instrument, EHIS will supply high quality data for scientific studies. For the GOES Level 1-B and Level 2 data products, protons and helium are distinguished in the EHIS using discriminator trigger logic. Measurements are provided in five energy bands. The instrumental cadence of these rates is 3 seconds. However, the primary Level 1-B proton and helium data products are 1-minute and 5-minute averages. The data latency is 1 minute, so data products can be used for real-time predictions as well as general science studies. Protons and helium, comprising approximately 99% of all energetic ions in space are of great importance for Space Weather predictions. We discuss the preliminary EHIS proton and helium data results and their application to Space Weather. The EHIS instrument development project was funded by NASA under contract NNG06HX01C.

Thermalization in high energy proton-nucleus collisions

International Nuclear Information System (INIS)

Wedemann, R.S.

1988-03-01

A relativistic proton-nucleus collision using the intranuclear cascade model is studied. The purpose is to verify the equilibration hypothesis at fragmentation time made by many nuclear fragmentation models. (author)

Escape of high-energy oxygen ions through magnetopause reconnection under northward IMF

Directory of Open Access Journals (Sweden)

S. Kasahara

2008-12-01

Full Text Available During a storm recovery phase on 15 May 2005, the Geotail spacecraft repeatedly observed high-energy (>180 keV oxygen ions in the dayside magnetosheath near the equatorial plane. We focused on the time period from 11:20 UT to 13:00 UT, when Geotail observed the oxygen ions and the interplanetary magnetic field (IMF was constantly northward. The magnetic reconnection occurrence northward and duskward of Geotail is indicated by the Walén analysis and convective flows in the magnetopause boundary layer. Anisotropic pitch angle distributions of ions suggest that high-energy oxygen ions escaped from the northward of Geotail along the reconnected magnetic field lines. From the low-energy particle precipitation in the polar cap observed by DMSP, which is consistent with magnetic reconnection occurring between the magnetosheath field lines and the magnetospheric closed field lines, we conclude that these oxygen ions are of ring current origin. Our results thus suggest a new escape route of oxygen ions during northward IMF. In the present event, this escape mechanism is more dominant than the leakage via the finite Larmor radius effect across the dayside equatorial magnetopause.

Slowing down and straggling of protons and heavy ions in matter

International Nuclear Information System (INIS)

Aernsbergen, L.M. van.

1986-01-01

The Doppler Shift Attenuation (DSA) method is widely used to measure lifetimes of nuclear states. However, many of the lifetimes resulting from DSA measurements display large variations which are caused by an insufficient knowledge of slowing down processes of nucleus recoils. The measurement of 'ranges' is an often used method to study these slowing down processes. In this kind of measurement the distributions of implanted ions are determined for example by the method of Rutherford backscattering or from the yield curve of a resonant nuclear reaction. In this thesis, research on energy-loss processes of protons and Si ions in aluminium is presented. The so-called Resonance Shift method has been improved for the measurements on the protons themselves. This method has only been used occasionally before. A new method has been developed, which is called the Transmission Doppler Shift Attenuation (TDSA) method, for the measurement on Si ions. (Auth.)

Separation of different ion structures in atmospheric pressure photoionization-ion mobility spectrometry-mass spectrometry (APPI-IMS-MS).

Science.gov (United States)

Laakia, Jaakko; Adamov, Alexey; Jussila, Matti; Pedersen, Christian S; Sysoev, Alexey A; Kotiaho, Tapio

2010-09-01

This study demonstrates how positive ion atmospheric pressure photoionization-ion mobility spectrometry-mass spectrometry (APPI-IMS-MS) can be used to produce different ionic forms of an analyte and how these can be separated. When hexane:toluene (9:1) is used as a solvent, 2,6-di-tert-butylpyridine (2,6-DtBPyr) and 2,6-di-tert-4-methylpyridine (2,6-DtB-4-MPyr) efficiently produce radical cations [M](+*) and protonated [M + H](+) molecules, whereas, when the sample solvent is hexane, protonated molecules are mainly formed. Interestingly, radical cations drift slower in the drift tube than the protonated molecules. It was observed that an oxygen adduct ion, [M + O(2)](+*), which was clearly seen in the mass spectra for hexane:toluene (9:1) solutions, shares the same mobility with radical cations, [M](+*). Therefore, the observed mobility order is most likely explained by oxygen adduct formation, i.e., the radical cation forming a heavier adduct. For pyridine and 2-tert-butylpyridine, only protonated molecules could be efficiently formed in the conditions used. For 1- and 2-naphthol it was observed that in hexane the protonated molecule typically had a higher intensity than the radical cation, whereas in hexane:toluene (9:1) the radical cation [M](+*) typically had a higher intensity than the protonated molecule [M + H](+). Interestingly, the latter drifts slower than the radical cation [M](+*), which is the opposite of the drift pattern seen for 2,6-DtBPyr and 2,6-DtB-4-MPyr. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Comparative Risk Predictions of Second Cancers After Carbon-Ion Therapy Versus Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Eley, John G., E-mail: jeley@som.umaryland.edu [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); University of Texas Graduate School of Biomedical Sciences, Houston, Texas (United States); Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland (United States); Friedrich, Thomas [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Homann, Kenneth L.; Howell, Rebecca M. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); University of Texas Graduate School of Biomedical Sciences, Houston, Texas (United States); Scholz, Michael; Durante, Marco [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Newhauser, Wayne D. [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, Baton Rouge, Louisiana (United States); Mary Bird Perkins Cancer Center, Baton Rouge, Louisiana (United States)

2016-05-01

Purpose: This work proposes a theoretical framework that enables comparative risk predictions for second cancer incidence after particle beam therapy for different ion species for individual patients, accounting for differences in relative biological effectiveness (RBE) for the competing processes of tumor initiation and cell inactivation. Our working hypothesis was that use of carbon-ion therapy instead of proton therapy would show a difference in the predicted risk of second cancer incidence in the breast for a sample of Hodgkin lymphoma (HL) patients. Methods and Materials: We generated biologic treatment plans and calculated relative predicted risks of second cancer in the breast by using two proposed methods: a full model derived from the linear quadratic model and a simpler linear-no-threshold model. Results: For our reference calculation, we found the predicted risk of breast cancer incidence for carbon-ion plans-to-proton plan ratio, , to be 0.75 ± 0.07 but not significantly smaller than 1 (P=.180). Conclusions: Our findings suggest that second cancer risks are, on average, comparable between proton therapy and carbon-ion therapy.

Optimization of proton and heavy ion therapy using an adaptive inversion algorithm

International Nuclear Information System (INIS)

Brahme, A.; Kaellman, P.; Lind, B.K.

1989-01-01

From the examples presented it is clear that the clinical advantages of high energy proton beams are considerable when optimally employed. Protons can generate almost any desired dose distribution in an arbitrary shaped target volume. When only ordinary uniform proton beams of fixed range modulation are available, the clinical advantages compared for example to high quality high energy electrons are not so pronounced. The new iterative inversion algorithm presented here therefore opens the door for precise and efficient use of the dose distributional advantages of high energy protons, pions and heavy ions. (author). 22 refs.; 7 figs

Protonation states of histidine and other key residues in deoxy normal human adult hemoglobin by neutron protein crystallography

International Nuclear Information System (INIS)

Kovalevsky, Andrey; Chatake, Toshiyuki; Shibayama, Naoya; Park, Sam-Yong; Ishikawa, Takuya; Mustyakimov, Marat; Fisher, S. Zoe; Langan, Paul; Morimoto, Yukio

2010-01-01

Using neutron diffraction analysis, the protonation states of 35 of 38 histidine residues were determined for the deoxy form of normal human adult hemoglobin. Distal and buried histidines may contribute to the increased affinity of the deoxy state for hydrogen ions and its decreased affinity for oxygen compared with the oxygenated form. The protonation states of the histidine residues key to the function of deoxy (T-state) human hemoglobin have been investigated using neutron protein crystallography. These residues can reversibly bind protons, thereby regulating the oxygen affinity of hemoglobin. By examining the OMIT F o − F c and 2F o − F c neutron scattering maps, the protonation states of 35 of the 38 His residues were directly determined. The remaining three residues were found to be disordered. Surprisingly, seven pairs of His residues from equivalent α or β chains, αHis20, αHis50, αHis58, αHis89, βHis63, βHis143 and βHis146, have different protonation states. The protonation of distal His residues in the α 1 β 1 heterodimer and the protonation of αHis103 in both subunits demonstrates that these residues may participate in buffering hydrogen ions and may influence the oxygen binding. The observed protonation states of His residues are compared with their ΔpK a between the deoxy and oxy states. Examination of inter-subunit interfaces provided evidence for interactions that are essential for the stability of the deoxy tertiary structure

Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

Directory of Open Access Journals (Sweden)

F. Catapano

2016-10-01

Full Text Available Spacecraft observations show that energetic ions are found in the Earth's magnetotail, with energies ranging from tens of keV to a few hundreds of keV. In this paper we carry out test particle simulations in which protons and other ion species are injected in the Vlasov magnetic field configurations obtained by Catapano et al. (2015. These configurations represent solutions of a generalized Harris model, which well describes the observed profiles in the magnetotail. In addition, three-dimensional time-dependent stochastic electromagnetic perturbations are included in the simulation box, so that the ion acceleration process is studied while varying the equilibrium magnetic field profile and the ion species. We find that proton energies of the order of 100 keV are reached with simulation parameters typical of the Earth's magnetotail. By changing the ion mass and charge, we can study the acceleration of heavy ions such as He+ +  and O+, and it is found that energies of the order of 100–200 keV are reached in a few seconds for He+ + , and about 100 keV for O+.

Double-digest RAD sequencing using Ion Proton semiconductor platform (ddRADseq-ion) with nonmodel organisms.

Science.gov (United States)

Recknagel, Hans; Jacobs, Arne; Herzyk, Pawel; Elmer, Kathryn R

2015-11-01

Research in evolutionary biology involving nonmodel organisms is rapidly shifting from using traditional molecular markers such as mtDNA and microsatellites to higher throughput SNP genotyping methodologies to address questions in population genetics, phylogenetics and genetic mapping. Restriction site associated DNA sequencing (RAD sequencing or RADseq) has become an established method for SNP genotyping on Illumina sequencing platforms. Here, we developed a protocol and adapters for double-digest RAD sequencing for Ion Torrent (Life Technologies; Ion Proton, Ion PGM) semiconductor sequencing. We sequenced thirteen genomic libraries of three different nonmodel vertebrate species on Ion Proton with PI chips: Arctic charr Salvelinus alpinus, European whitefish Coregonus lavaretus and common lizard Zootoca vivipara. This resulted in ~962 million single-end reads overall and a mean of ~74 million reads per library. We filtered the genomic data using Stacks, a bioinformatic tool to process RAD sequencing data. On average, we obtained ~11,000 polymorphic loci per library of 6-30 individuals. We validate our new method by technical and biological replication, by reconstructing phylogenetic relationships, and using a hybrid genetic cross to track genomic variants. Finally, we discuss the differences between using the different sequencing platforms in the context of RAD sequencing, assessing possible advantages and disadvantages. We show that our protocol can be used for Ion semiconductor sequencing platforms for the rapid and cost-effective generation of variable and reproducible genetic markers. © 2015 John Wiley & Sons Ltd.

Numerical simulations of gas mixing effect in electron cyclotron resonance ion sources

Directory of Open Access Journals (Sweden)

V. Mironov

2017-01-01

Full Text Available The particle-in-cell Monte Carlo collisions code nam-ecris is used to simulate the electron cyclotron resonance ion source (ECRIS plasma sustained in a mixture of Kr with O_{2}, N_{2}, Ar, Ne, and He. The model assumes that ions are electrostatically confined in the ECR zone by a dip in the plasma potential. A gain in the extracted krypton ion currents is seen for the highest charge states; the gain is maximized when oxygen is used as a mixing gas. The special feature of oxygen is that most of the singly charged oxygen ions are produced after the dissociative ionization of oxygen molecules with a large kinetic energy release of around 5 eV per ion. The increased loss rate of energetic lowly charged ions of the mixing element requires a building up of the retarding potential barrier close to the ECR surface to equilibrate electron and ion losses out of the plasma. In the mixed plasmas, the barrier value is large (∼1  V compared to pure Kr plasma (∼0.01  V, with longer confinement times of krypton ions and with much higher ion temperatures. The temperature of the krypton ions is increased because of extra heating by the energetic oxygen ions and a longer time of ion confinement. In calculations, a drop of the highly charged ion currents of lighter elements is observed when adding small fluxes of krypton into the source. This drop is caused by the accumulation of the krypton ions inside plasma, which decreases the electron and ion confinement times.

Sodium ions as substitutes for protons in the gastric H,K-ATPase

International Nuclear Information System (INIS)

Polvani, C.; Sachs, G.; Blostein, R.

1989-01-01

In view of the striking homology among various ion-translocating ATPases including Na,K-ATPase, Ca-ATPase, and H,K-ATPase, and the recent evidence that protons can replace cytoplasmic sodium as well as potassium in the reaction mechanism of the Na,K-ATPase (Polvani, C., and Blostein, R. (1988) J. Biol. Chem. 263, 16757-16763), we studied the role of sodium as a substitute for protons in the H,K-ATPase reaction. Using hog gastric H,K-ATPase-rich inside-out membrane vesicles we observed 22Na+ influx which was stimulated by intravesicular potassium ions (K+i) at pH 8.5 but not at pH 7.1. This sodium influx was observed in medium containing ATP and was inhibited by vanadate and SCH28080, a selective inhibitor of the gastric H,K-ATPase. At least 2-fold accumulation of sodium was observed at pH 8.5. Experiments aimed to determine the sidedness of the alkaline pH requirement for K+i-dependent sodium influx showed that K+i-activated sodium influx depends on pHout and is unaffected by changes in pHin. These results support the conclusion that sodium ions substitute for protons in the H,K-ATPase reaction mechanism and provide evidence for a similarity in ion selectivity and/or binding domains of the Na,K-ATPase and the gastric H,K-ATPase enzymes

Commissioning of the ECR ion source of the high intensity proton injector of the Facility for Antiproton and Ion Research (FAIR)

Science.gov (United States)

Tuske, O.; Chauvin, N.; Delferriere, O.; Fils, J.; Gauthier, Y.

2018-05-01

The CEA at Saclay is in charge of developing and building the ion source and the low energy line of the proton linac of the FAIR (Facility for Antiproton and Ion Research) accelerator complex located at GSI (Darmstadt) in Germany. The FAIR facility will deliver stable and rare isotope beams covering a huge range of intensities and beam energies for experiments in the fields of atomic physics, plasma physics, nuclear physics, hadron physics, nuclear matter physics, material physics, and biophysics. A significant part of the experimental program at FAIR is dedicated to antiproton physics that requires an ultimate number 7 × 1010 cooled pbar/h. The high-intensity proton beam that is necessary for antiproton production will be delivered by a dedicated 75 mA/70 MeV proton linac. A 2.45 GHz microwave ion source will deliver a 100 mA H+ beam pulsed at 4 Hz with an energy of 95 keV. A 2 solenoids low energy beam transport line allows the injection of the proton beam into the radio frequency quadrupole (RFQ) within an acceptance of 0.3π mm mrad (norm. rms). An electrostatic chopper system located between the second solenoid and the RFQ is used to cut the beam macro-pulse from the source to inject 36 μs long beam pulses into the RFQ. At present time, a Ladder-RFQ is under construction at the University of Frankfurt. This article reports the first beam measurements obtained since mid of 2016. Proton beams have been extracted from the ECR ion source and analyzed just after the extraction column on a dedicated diagnostic chamber. Emittance measurements as well as extracted current and species proportion analysis have been performed in different configurations of ion source parameters, such as magnetic field profile, radio frequency power, gas injection, and puller electrode voltage.

A Particle X-ray Temporal Diagnostic (PXTD) for studies of kinetic, multi-ion effects, and ion-electron equilibration rates in Inertial Confinement Fusion plasmas at OMEGA (invited)

International Nuclear Information System (INIS)

Sio, H.; Frenje, J. A.; Katz, J.; Stoeckl, C.; Weiner, D.

2016-01-01

Here, a Particle X-ray Temporal Diagnostic (PXTD) has been implemented on OMEGA for simultaneous time-resolved measurements of several nuclear products as well as the x-ray continuum produced in High Energy Density Plasmas and Inertial Confinement Fusion implosions. The PXTD removes systematic timing uncertainties typically introduced by using multiple instruments, and it has been used to measure DD, DT, D"3He, and T"3He reaction histories and the emission history of the x-ray core continuum with relative timing uncertainties within ±10-20 ps. This enables, for the first time, accurate and simultaneous measurements of the x-ray emission histories, nuclear reaction histories, their time differences, and measurements of T_i(t) and T_e(t) from which an assessment of multiple-ion-fluid effects, kinetic effects during the shock-burn phase, and ion-electron equilibration rates can be made.

Biophase equilibration times.

Science.gov (United States)

Veng-Pedersen, P; Mandema, J W; Danhof, M

1991-09-01

Various methods for describing how quickly a drug equilibrates at the biophase are proposed. The biophase equilibration time (BET) is the time it takes the biophase drug level to reach a given percentage (p) of its predicted steady state in a drug administration that leads to a steady-state condition. The time to reach biophase equilibrium may be defined as the BET value for p = 95, and the 50% biophase equilibration time is obtained when p = 50. Biophase equilibration profiles (BEPs), obtained by plotting p versus BET, give a dynamic representation of the approach to equilibrium and may serve as an indicator of the rate of drug delivery to the biophase. A pharmacodynamic system analysis method is proposed to determine BETs and BEPs from the biophase conduction function. The approach is demonstrated using pharmacodynamic data from the CNS effect of amobarbital evaluated by an aperiodic analysis of EEG recordings. The relevance of the BET and/or BEP principles in optimal computer-controlled drug infusion, drug design, and evaluation of targeted drug delivery is discussed. Both vascular and extravascular drug administrations are considered in the analysis.

Improvement of proton source based on cylindrical inertial electrostatic confinement fusion with ion source

International Nuclear Information System (INIS)

Yamauchi, Kunihito; Ohura, Sonoe; Tashiro, Atsushi; Watanabe, Masato; Okino, Akitoshi; Kohno, Toshiyuki; Hotta, Eiki; Yuura, Morimasa

2005-01-01

Inertial Electrostatic Confinement Fusion (IECF) device is a compact fusion proton/neutron source with an extremely simple configuration, high controllability, and hence high safety. Therefore, it has been studied for practical use as a portable neutron/proton source for various applications such as landmine detection and medical positron emission tomography. However, some problems remain for the practical use, and the most critical one is the insufficiency of absolute neutron/proton yields. In this study, a new IECF device was designed and tested to obtain high neutron/proton yields. The key features of the new device are the cylindrical electrode configuration in consideration of better electrostatic confinement of ions and extraction of protons, and an integrated ion source that consists of sixteen ferrite magnets and biasing the grid anode. To investigate the performance characteristics of the device and the effect of the ion source, three kinds of experimental setup were used for comparison. At first, the device was operated with the basic setup. Then a cusp magnetic field was applied by using ferrite magnets, and the grid anode was negatively biased. As a result, it was confirmed that the ion source works effectively. At the same voltage and current, the obtained neutron production rate was about one order of magnitude higher than that of the conventional spherical IECF device. The maximum neutron production rate of 6.8x10 9 n/s was obtained at a pulsed discharge of -70 kV and 10 A with an anode bias voltage of -1.0 kV. (author)

Induction of anchorage-independent growth in primary human cells exposed to protons or HZE ions separately or in dual exposures.

Science.gov (United States)

Sutherland, B M; Cuomo, N C; Bennett, P V

2005-10-01

Travelers on space missions will be exposed to a complex radiation environment that includes protons and heavy charged particles. Since protons are present at much higher levels than are heavy ions, the most likely scenario for cellular radiation exposure will be proton exposure followed by a hit by a heavy ion. Although the effects of individual ion species on human cells are being investigated extensively, little is known about the effects of exposure to both radiation types. One useful measure of mammalian cell damage is induction of the ability to grow in a semi-solid agar medium highly inhibitory to the growth of normal human cells, termed neoplastic transformation. Using primary human cells, we evaluated induction of soft-agar growth and survival of cells exposed to protons only or to heavy charged particles (600 MeV/nucleon silicon) only as well as of cells exposed to protons followed after a 4-day interval by silicon ions. Both ions alone efficiently transformed the human cells to anchorage-independent growth. Initial experiments indicate that the dose responses for neoplastic transformation of cells exposed to protons and then after 4 days to silicon ions appear similar to that of cells exposed to silicon ions alone.

Performance evaluation of oxygen adsorbents using negative corona discharge–ion mobility spectrometry

Energy Technology Data Exchange (ETDEWEB)

Azadkish, Kamal; Jafari, Mohammad T., E-mail: jafari@cc.iut.ac.ir; Ghaziaskar, Hassan S.

2017-02-08

Trace amounts of oxygen was determined using negative corona discharge as an ionization source for ion mobility spectrometry. A point-in-cylinder geometry with novel design was used to establish the corona discharge without interferences of negative ions such as NO{sub X}{sup −}. The desirable background spectrum shows only electrons peak, providing the instrument capable of trace analysis of oxygen in gaseous samples. The limit of detection and linear dynamic range with high coefficient of determination (r{sup 2} = 0.9997), were obtained for oxygen as 8.5 and 28–14204 ppm, respectively. The relative standard deviations of the method for intraday and interday were obtained 4 and 11%, respectively. The satisfactory results revealed the ability of the negative corona discharge ion mobility spectrometry for investigating the performance of synthesized oxygen adsorbents in nitrogen streams. Two oxygen scavengers of MnO and Cu powder were prepared and the optimum temperature of the reactor containing MnO and Cu powder were obtained as 180 and 230 °C, respectively. Due to higher lifetime of copper powder, it was selected as the oxygen scavenger and some parameters such as: the type of adsorbent support, the size of adsorbent particles, and the amount of copper were studied for preparation of more efficient oxygen adsorbent. - Highlights: • Analysis of oxygen using negative corona discharge-ion mobility spectrometry was investigated for the first time. • Novel designed point-in-cylinder geometry was used to establish the corona discharge without interferences of negative ions. • The method was utilized to evaluate the performance of some synthesized oxygen scavengers.

Structure of Ion Outflow in the Martian Magnetotail

Science.gov (United States)

McFadden, J. P.; Mitchell, D.; Luhmann, J. G.; Connerney, J. E. P.; Jakosky, B. M.

2017-12-01

The Suprathermal And Thermal Ion Composition (STATIC) sensor on the MAVEN spacecraft provides a detailed look at the structure of ion outflow in the Martian magnetotail including ion composition, energization, and flow. Mars' magnetotail contains a mixture of cold (multi-species ions, tailward-moving cold multi-species ions, suprathermal ions of a few tens of eV, warm (about 100 eV) proton populations, and heavy (primarily O+) pickup ions at energies from 1 to 10 keV which may display several simultaneous peaks in energy flux. The cold tailward-moving ions represent a significant fraction of the Martian ion loss, perhaps comparable to loses from molecular oxygen dissociation. The suprathermal tail that accompanies the cold ions varies greatly and provides clues to ion escape. The warm protons, on first examination, appear to be of sheath origin, displaying a similar energy distribution and accompanied by a tenuous warm population at M/Q=2 (which could be either solar wind alphas or molecular hydrogen ions of ionospheric origin). STATIC produces a weak ghost peak at M/Q=11-12 when observing molecular hydrogen ions, but not alphas, often allowing the instrument to distinguish the source of protons. Measurements show the warm protons are of ionospheric origin in the central tail and transition to sheath plasma in the umbra. Energetic (1-10 keV) pickup oxygen in the magnetotail is produced on the nightside, near the pole where the IMF convection electric field points toward the planet, the same hemisphere where sputtering occurs. When two spectral peaks are observed, these tailward-moving ions differ in direction by relatively small angles (about 20 degrees). These peaks can persist for tens of minutes indicating approximately time-stationary acceleration, and therefore acceleration in potential fields. Magnetotail structure and geometry can be inferred not only from the local magnetic field, but also from the measured electron distributions which indicate source

Evaluation of exome variants using the Ion Proton Platform to sequence error-prone regions.

Science.gov (United States)

Seo, Heewon; Park, Yoomi; Min, Byung Joo; Seo, Myung Eui; Kim, Ju Han

2017-01-01

The Ion Proton sequencer from Thermo Fisher accurately determines sequence variants from target regions with a rapid turnaround time at a low cost. However, misleading variant-calling errors can occur. We performed a systematic evaluation and manual curation of read-level alignments for the 675 ultrarare variants reported by the Ion Proton sequencer from 27 whole-exome sequencing data but that are not present in either the 1000 Genomes Project and the Exome Aggregation Consortium. We classified positive variant calls into 393 highly likely false positives, 126 likely false positives, and 156 likely true positives, which comprised 58.2%, 18.7%, and 23.1% of the variants, respectively. We identified four distinct error patterns of variant calling that may be bioinformatically corrected when using different strategies: simplicity region, SNV cluster, peripheral sequence read, and base inversion. Local de novo assembly successfully corrected 201 (38.7%) of the 519 highly likely or likely false positives. We also demonstrate that the two sequencing kits from Thermo Fisher (the Ion PI Sequencing 200 kit V3 and the Ion PI Hi-Q kit) exhibit different error profiles across different error types. A refined calling algorithm with better polymerase may improve the performance of the Ion Proton sequencing platform.

Evaluation of exome variants using the Ion Proton Platform to sequence error-prone regions.

Directory of Open Access Journals (Sweden)

Heewon Seo

Full Text Available The Ion Proton sequencer from Thermo Fisher accurately determines sequence variants from target regions with a rapid turnaround time at a low cost. However, misleading variant-calling errors can occur. We performed a systematic evaluation and manual curation of read-level alignments for the 675 ultrarare variants reported by the Ion Proton sequencer from 27 whole-exome sequencing data but that are not present in either the 1000 Genomes Project and the Exome Aggregation Consortium. We classified positive variant calls into 393 highly likely false positives, 126 likely false positives, and 156 likely true positives, which comprised 58.2%, 18.7%, and 23.1% of the variants, respectively. We identified four distinct error patterns of variant calling that may be bioinformatically corrected when using different strategies: simplicity region, SNV cluster, peripheral sequence read, and base inversion. Local de novo assembly successfully corrected 201 (38.7% of the 519 highly likely or likely false positives. We also demonstrate that the two sequencing kits from Thermo Fisher (the Ion PI Sequencing 200 kit V3 and the Ion PI Hi-Q kit exhibit different error profiles across different error types. A refined calling algorithm with better polymerase may improve the performance of the Ion Proton sequencing platform.

Method for calculating ionic and electronic defect concentrations in y-stabilised zirconia

Energy Technology Data Exchange (ETDEWEB)

Poulsen, F W [Risoe National Lab., Materials Research Dept., Roskilde (Denmark)

1997-10-01

A numerical (trial and error) method for calculation of concentration of ions, vacancies and ionic and electronic defects in solids (Brouwer-type diagrams) is presented. No approximations or truncations of the set of equations describing the chemistry for the various defect regions are used. Doped zirconia and doped thoria with simultaneous presence of protonic and electronic defects are taken as examples: 7 concentrations as function of oxygen partial pressure and/or water vapour partial pressure are determined. Realistic values for the equilibrium constants for equilibration with oxygen gas and water vapour, as well as for the internal equilibrium between holes and electrons were taken from the literature. The present mathematical method is versatile - it has also been employed by the author to treat more complex systems, such as perovskite structure oxides with over- and under-stoichiometry in oxygen, cation vacancies and simultaneous presence of protons. (au) 6 refs.

Development of ion/proton beam equipment for industrial uses

Energy Technology Data Exchange (ETDEWEB)

Choi, Byung Ho; Lee, J. H.; Cho, Y. S.; Joo, P. K.; Kang, S. S.; Song, W. S.; Kim, H. J.; Chang, G. H.; Bang, S. W

1999-12-01

KAERI has possessed design and fabrication technologies of various ion sources including Duoplasmatron and DuoPiGatron developed by R and D projects of the long-term nuclear technology development program. In order to industrialize ion beam equipments utilizing these ion sources, a technology transfer project for a technology transfer project for a domestic firm has been performed. Under this project, engineers of the firm have been trained through classroom lectures of ion beam principles and OJT, an ion/proton beam equipment (DEMO equipment) has been designed, assembled and commissioned jointly with the engineers. Quality of the ion sources has been quantified, and technologies for ion beam equipment construction, functional test and application research have been developed. The DEMO equipment, which consists of an ion source, power supplies, vacuum, cooling and target systems, has been fabricated and tested to secure stability and reliability for industrial uses. Various characteristic tests including high voltage insulation, beam extraction, beam current measuring, etc. have been performed. This DEMO can be utilized for ion sources development as well as ion beam process development for various industrial products. Engineers of the firm have been trained for the industrialization of ion beam equipment and joined in beam application technology development to create industrial needs of beam equipment. (author)

Electrochemistry suggests proton access from the exit site to the binuclear center in Paracoccus denitrificans cytochrome c oxidase pathway variants.

Science.gov (United States)

Meyer, Thomas; Melin, Frédéric; Richter, Oliver-M H; Ludwig, Bernd; Kannt, Aimo; Müller, Hanne; Michel, Hartmut; Hellwig, Petra

2015-02-27

Two different pathways through which protons access cytochrome c oxidase operate during oxygen reduction from the mitochondrial matrix, or the bacterial cytoplasm. Here, we use electrocatalytic current measurements to follow oxygen reduction coupled to proton uptake in cytochrome c oxidase isolated from Paracoccus denitrificans. Wild type enzyme and site-specific variants with defects in both proton uptake pathways (K354M, D124N and K354M/D124N) were immobilized on gold nanoparticles, and oxygen reduction was probed electrochemically in the presence of varying concentrations of Zn(2+) ions, which are known to inhibit both the entry and the exit proton pathways in the enzyme. Our data suggest that under these conditions substrate protons gain access to the oxygen reduction site via the exit pathway. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Proton polarizing system with Ar-ion laser for p-vector-RI scattering experiments

International Nuclear Information System (INIS)

Wakui, T.; Hatano, M.; Sakai, H.; Uesaka, T.; Tamii, A.

2005-01-01

A proton polarizing system for use in scattering experiments with radioactive isotope beams is described. Protons in a naphthalene crystal doped with pentacene are polarized in a magnetic field of 0.3T at 100K by transferring a large population difference among the photo-excited triplet states of pentacene to the hydrogen nuclei. An Ar-ion laser, which demands minimal maintenance during scattering experiments, is employed to excite the pentacene molecules. A proton polarization of 37% is obtained

Anhydrous thallium hydrogen L-glutamate: polymer networks formed by sandwich layers of oxygen-coordinated thallium ions cores shielded by hydrogen L-glutamate counterions.

Science.gov (United States)

Bodner, Thomas; Wirnsberger, Bianca; Albering, Jörg; Wiesbrock, Frank

2011-11-07

Anhydrous thallium hydrogen L-glutamate [Tl(L-GluH)] crystallizes from water (space group P2(1)) with a layer structure in which the thallium ions are penta- and hexacoordinated exclusively by the oxygen atoms of the γ-carboxylate group of the hydrogen L-glutamate anions to form a two-dimensional coordination polymer. The thallium-oxygen layer is composed of Tl(2)O(2) and TlCO(2) quadrangles and is only 3 Å high. Only one hemisphere of the thallium ions participates in coordination, indicative of the presence of the 6s(2) lone pair of electrons. The thallium-oxygen assemblies are shielded by the hydrogen l-glutamate anions. Only the carbon atom of the α-carboxylate group deviates from the plane spanned by the thallium ions, the γ-carboxylate groups and the proton bearing carbon atoms, which are in trans conformation. Given the abundance of L-glutamic and L-aspartic acid in biological systems on the one hand and the high toxicity of thallium on the other hand, it is worth mentioning that the dominant structural motifs in the crystal structure of [Tl(L-GluH)] strongly resemble their corresponding analogues in the crystalline phase of [K(L-AspH)(H(2)O)(2)].

The C2H3O+ chemi-ion acetyl cation or O-protonated ketene

DEFF Research Database (Denmark)

Egsgaard, H.; Carlsen, L.

1995-01-01

The C2H3O+ chemi-ion sampled from a premixed methane/oxygen flame has been demonstrated to be the acetyl cation based on ion-molecule reactions with isoprene and 1,3-dioxolane.......The C2H3O+ chemi-ion sampled from a premixed methane/oxygen flame has been demonstrated to be the acetyl cation based on ion-molecule reactions with isoprene and 1,3-dioxolane....

Electron capture by fast protons from helium-like ions

International Nuclear Information System (INIS)

Samanta, R.; Purkait, M.

2011-01-01

Four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation have been applied to calculate the single-electron capture cross sections by fast protons through some helium-like ions in a large energy range from 30-1000 keV. In this model, distortion has been taken into account in the entrance channel. In the final channel, the passive electron plays the role of screening of the target ion. However, continuum states of the projectile and the electron in the field of the residual target ion are included. The comparison of the results is made with those of other theoretical investigations and experimental findings. The present calculated results are found to be in good agreement with the available experimental findings. (authors)

Effect of equilibration time on Pu desorption from goethite

International Nuclear Information System (INIS)

Wong, Jennifer C.; Powell, Brian A.; Zavarin, Mavrik; Begg, James D.; Kersting, Annie B.

2015-01-01

It has been suggested that strongly sorbing ions such as plutonium may become irreversibly bound to mineral surfaces over time which has implications for near- and far-field transport of Pu. Batch adsorption-desorption data were collected as a function of time and pH to study the surface stability of Pu on goethite. Pu(IV) was adsorbed to goethite over the pH range 4.2 to 6.6 for different periods of time (1, 6, 15, 34 and 116 d). Following adsorption, Pu was leached from the mineral surface with desferrioxamine B (DFOB), a complexant capable of effectively competing with the goethite surface for Pu. The amount of Pu desorbed from the goethite was found to vary as a function of the adsorption equilibration time, with less Pu removed from the goethite following longer adsorption periods. This effect was most pronounced at low pH. Logarithmic desorption distribution ratios for each adsorption equilibration time were fit to a pH-dependent model. Model slopes decreased between 1 and 116 d adsorption time, indicating that overall Pu(IV) surface stability on goethite surfaces becomes less dependent on pH with greater adsorption equilibration time. The combination of adsorption and desorption kinetic data suggest that non-redox aging processes affect Pu sorption behavior on goethite.

A high performance cathode for proton conducting solid oxide fuel cells

KAUST Repository

Wang, Zhiquan; Yang, Wenqiang; Shafi, Shahid Pottachola; Bi, Lei; Wang, Zhenbin; Peng, Ranran; Xia, Changrong; Liu, Wei; Lu, Yalin

2015-01-01

. In the intermediate temperature range (500-700°C), SOFCs based on proton conducting electrolytes (PSOFCs) display unique advantages over those based on oxygen ion conducting electrolytes. A key obstacle to the practical operation of past P-SOFCs is the poor stability

An Antiproton Ion Collider (AIC) for Measuring Neutron and Proton Distributions in Stable and Radioactive Nuclei

International Nuclear Information System (INIS)

Kienle, Paul

2005-01-01

An antiproton-ion collider is proposed to independently determine mean square radii for protons and neutrons in stable and short lived nuclei by means of antiproton absorption at medium energies. The experiment makes use of the electron ion collider complex (ELISE) of the GSI FAIR project with appropriate modifications of the electron ring to store, cool and collide antiprotons of 30 MeV energy with 740A MeV energy ions.The total absorption cross-section of antiprotons by the stored ions will be measured by detecting their loss by means of the Schottky noise spectroscopy method. Cross sections for the absorption on protons and neutrons, respectively, will be studied by detection of residual nuclei with A-1 either by the Schottky method or by analysing them in recoil detectors after the first dipole stage of the NESR following the interaction zone. With a measurement of the A-1 fragment momentum distribution, one can test the momentum wave functions of the annihilated neutron and proton, respectively. Furthermore by changing the incident ion energy the tails of neutron and proton distribution can be measured.The absorption cross section is at asymptotic energies in leading order proportional to the mean square radius of the nucleus. Predicted cross sections and luminosities show that the method is applicable to nuclei with production rates of about 105 s-1 or lower, depending on the lifetime of the ions in the NESR, and for half-lives down to 1 second

Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

KAUST Repository

Alquaity, Awad

2016-08-22

Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

Dependence of proton beam polarization on ion source transition configurations; Determination de la polarisation du faisceau de protons pour les quatre configurations des transitions de la source d`ions

Energy Technology Data Exchange (ETDEWEB)

Arvieux, J.; Ausset, P.; Ball, J.; Beauvais, P.Y.; Bedfer, Y.; Chamouard, P.A.; Fontaine, J.M.; Kunne, R.; Lagniel, J.M.; Sans, J.L. [Laboratoire National Saturne - Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France); Allgower, Ch.; Kasprzyk, T.E.; Spinka, H.M. [ANL-HEP, Argonne (United States); Bystricky, J.; Lehar, F.; Lesquen, A. de [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Demiere, Ph.; Rapin, D.; Teglia, A. [Geneva Univ. (Switzerland). Dept. de Physique Nucleaire et Corpusculaire; Janout, Z. [Czech Technical Univ., Prague (Czech Republic). Faculty of Civil Engineering; Kalinnikov, V.A.; Khachaturov, B.A.; Popov, A.A. [Laboratory of Nuclear Problems, JINR, Moscow (Russian Federation); Prokofiev, A.N.; Vikhrov, V.V.; Zhdanov, A.A. [Nuclear Physics Inst., St. Petersburg (Russian Federation)

1997-12-31

Considerable anomalies were observed in recorded pp elastic scattering spin dependent data at several proton beam energies at SATURNE II. These results suggested that the discrepancies are related to the polarized ion source. In order to understand the observed effects, the proton beam polarizations for each ion source state were determined separately. Convenient procedures, allowing to determine the beam polarization from a beam-line polarimeter are presented. Two distinct experiments are necessary for this purpose. In the first one the LEFT-RIGHT instrumental asymmetry of the beam polarimeter arms is determined. In the second one this correction factor is applied to asymmetries measured with the beam from the polarized ion source in different polarization states. Both experiments determined the scattering asymmetries for all four polarized source states as functions of different source parameters. The measurements were carried out at the proton beam kinetic energy 0.80 GeV, where the pp elastic scattering analyzing power is at its maximum. Results show that the so called `unpolarized states` of the source are polarized, whereas the absolute values of the beam polarizations in `polarized states` are equal. It was observed that the hexapole lens of the ion source provides some beam polarization in the absence of any transition. The beam polarization as function of the hexapole current, of the transition efficiencies and of the rotation solenoid current has been studied. It is also shown, how one way obtain a strictly unpolarized beam using the polarized source only. The results obtained with the SATURNE II ion source HYPERION may be also valid for other accelerators and sources. (authors) 10 refs.

The amazing world of smashed protons and lead ions

CERN Multimedia

Antonella Del Rosso

2013-01-01

When a single proton (p) is smashed against a lead ion (Pb), unexpected events may occur: in the most violent p-Pb collisions, correlations of particles exhibit similar features as in lead-lead collisions where quark-gluon plasma is formed. This and other amazing results were presented by the ALICE experiment at the SQM2013 conference held in Birmingham from 21 to 27 July.   Event display from the proton-lead run, in January 2013. This event was generated by the High Level Trigger (HLT) of the ALICE experiment. “Jet quenching” is one of the most powerful signatures of quark-gluon plasma (QGP) formed in high-energy lead-lead collisions. QGP is expected to exist only in specific conditions involving extremely hot temperatures and a very high particle concentration. These conditions are not expected to apply in the case of less “dense” particle collisions such as proton-lead collisions. “When we observe the results of these collisions in ALICE, ...

Sputtering of solid nitrogen and oxygen by keV hydrogen ions

DEFF Research Database (Denmark)

Ellegaard, O.; Schou, Jørgen; Stenum, B.

1994-01-01

Electronic sputtering of solid nitrogen and oxygen by keV hydrogen ions has been studied at two low-temperature setups. The yield of the sputtered particles has been determined in the energy regime 4-10 keV for H+, H-2+ and H-3+ ions. The yield for oxygen is more than a factor of two larger than...... that for nitrogen. The energy distributions of the sputtered N2 and O2 molecules were measured for hydrogen ions in this energy regime as well. The yields from both solids turn out to depend on the sum of the stopping power of all atoms in the ion. The yield increases as a quadratic function of the stopping power...

Differential regulation of proton-sensitive ion channels by phospholipids: a comparative study between ASICs and TRPV1.

Directory of Open Access Journals (Sweden)

Hae-Jin Kweon

Full Text Available Protons are released in pain-generating pathological conditions such as inflammation, ischemic stroke, infection, and cancer. During normal synaptic activities, protons are thought to play a role in neurotransmission processes. Acid-sensing ion channels (ASICs are typical proton sensors in the central nervous system (CNS and the peripheral nervous system (PNS. In addition to ASICs, capsaicin- and heat-activated transient receptor potential vanilloid 1 (TRPV1 channels can also mediate proton-mediated pain signaling. In spite of their importance in perception of pH fluctuations, the regulatory mechanisms of these proton-sensitive ion channels still need to be further investigated. Here, we compared regulation of ASICs and TRPV1 by membrane phosphoinositides, which are general cofactors of many receptors and ion channels. We observed that ASICs do not require membrane phosphatidylinositol 4-phosphate (PI(4P or phosphatidylinositol 4,5-bisphosphate (PI(4,5P2 for their function. However, TRPV1 currents were inhibited by simultaneous breakdown of PI(4P and PI(4,5P2. By using a novel chimeric protein, CF-PTEN, that can specifically dephosphorylate at the D3 position of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5P3, we also observed that neither ASICs nor TRPV1 activities were altered by depletion of PI(3,4,5P3 in intact cells. Finally, we compared the effects of arachidonic acid (AA on two proton-sensitive ion channels. We observed that AA potentiates the currents of both ASICs and TRPV1, but that they have different recovery aspects. In conclusion, ASICs and TRPV1 have different sensitivities toward membrane phospholipids, such as PI(4P, PI(4,5P2, and AA, although they have common roles as proton sensors. Further investigation about the complementary roles and respective contributions of ASICs and TRPV1 in proton-mediated signaling is necessary.

Quantification of the Relative Biological Effectiveness for Ion Beam Radiotherapy: Direct Experimental Comparison of Proton and Carbon Ion Beams and a Novel Approach for Treatment Planning

International Nuclear Information System (INIS)

Elsaesser, Thilo; Weyrather, Wilma K.; Friedrich, Thomas; Durante, Marco; Iancu, Gheorghe; Kraemer, Michael; Kragl, Gabriele; Brons, Stephan; Winter, Marcus; Weber, Klaus-Josef; Scholz, Michael

2010-01-01

Purpose: To present the first direct experimental in vitro comparison of the biological effectiveness of range-equivalent protons and carbon ion beams for Chinese hamster ovary cells exposed in a three-dimensional phantom using a pencil beam scanning technique and to compare the experimental data with a novel biophysical model. Methods and Materials: Cell survival was measured in the phantom after irradiation with two opposing fields, thus mimicking the typical patient treatment scenario. The novel biophysical model represents a substantial extension of the local effect model, previously used for treatment planning in carbon ion therapy for more than 400 patients, and potentially can be used to predict effectiveness of all ion species relevant for radiotherapy. A key feature of the new approach is the more sophisticated consideration of spatially correlated damage induced by ion irradiation. Results: The experimental data obtained for Chinese hamster ovary cells clearly demonstrate that higher cell killing is achieved in the target region with carbon ions as compared with protons when the effects in the entrance channel are comparable. The model predictions demonstrate agreement with these experimental data and with data obtained with helium ions under similar conditions. Good agreement is also achieved with relative biological effectiveness values reported in the literature for other cell lines for monoenergetic proton, helium, and carbon ions. Conclusion: Both the experimental data and the new modeling approach are supportive of the advantages of carbon ions as compared with protons for treatment-like field configurations. Because the model predicts the effectiveness for several ion species with similar accuracy, it represents a powerful tool for further optimization and utilization of the potential of ion beams in tumor therapy.

Relaxation dynamics and transformation kinetics of deeply supercooled water: Temperature, pressure, doping, and proton/deuteron isotope effects.

Science.gov (United States)

Lemke, Sonja; Handle, Philip H; Plaga, Lucie J; Stern, Josef N; Seidl, Markus; Fuentes-Landete, Violeta; Amann-Winkel, Katrin; Köster, Karsten W; Gainaru, Catalin; Loerting, Thomas; Böhmer, Roland

2017-07-21

Above its glass transition, the equilibrated high-density amorphous ice (HDA) transforms to the low-density pendant (LDA). The temperature dependence of the transformation is monitored at ambient pressure using dielectric spectroscopy and at elevated pressures using dilatometry. It is found that near the glass transition temperature of deuterated samples, the transformation kinetics is 300 times slower than the structural relaxation, while for protonated samples, the time scale separation is at least 30 000 and insensitive to doping. The kinetics of the HDA to LDA transformation lacks a proton/deuteron isotope effect, revealing that this process is dominated by the restructuring of the oxygen network. The x-ray diffraction experiments performed on samples at intermediate transition stages reflect a linear combination of the LDA and HDA patterns implying a macroscopic phase separation, instead of a local intermixing of the two amorphous states.

Relaxation dynamics and transformation kinetics of deeply supercooled water: Temperature, pressure, doping, and proton/deuteron isotope effects

Science.gov (United States)

Lemke, Sonja; Handle, Philip H.; Plaga, Lucie J.; Stern, Josef N.; Seidl, Markus; Fuentes-Landete, Violeta; Amann-Winkel, Katrin; Köster, Karsten W.; Gainaru, Catalin; Loerting, Thomas; Böhmer, Roland

2017-07-01

Above its glass transition, the equilibrated high-density amorphous ice (HDA) transforms to the low-density pendant (LDA). The temperature dependence of the transformation is monitored at ambient pressure using dielectric spectroscopy and at elevated pressures using dilatometry. It is found that near the glass transition temperature of deuterated samples, the transformation kinetics is 300 times slower than the structural relaxation, while for protonated samples, the time scale separation is at least 30 000 and insensitive to doping. The kinetics of the HDA to LDA transformation lacks a proton/deuteron isotope effect, revealing that this process is dominated by the restructuring of the oxygen network. The x-ray diffraction experiments performed on samples at intermediate transition stages reflect a linear combination of the LDA and HDA patterns implying a macroscopic phase separation, instead of a local intermixing of the two amorphous states.

Surface oxygen vacancy and oxygen permeation flux limits of perovskite ion transport membranes

KAUST Repository

Hunt, Anton; Dimitrakopoulos, Georgios; Ghoniem, Ahmed F.

2015-01-01

© 2015 Elsevier B.V. The mechanisms and quantitative models for how oxygen is separated from air using ion transport membranes (ITMs) are not well understood, largely due to the experimental complexity for determining surface exchange reactions

Mixed ion beams near transition energy

International Nuclear Information System (INIS)

Hancock, S.

1991-01-01

The standard derivations of the energy and phase of the synchronous particle in a proton accelerator assume, as if by definition, that said synchronous particle lies on the central orbit of the machine. This is manifestly unjustified in the particular case of the acceleration near transition of a mixture of ions, when a small difference in charge-to-mass ratio can produce a large radial separation of the different ion species. The development of a simple derivation of the parameters of the synchronous particle that involves no such a priori constraint has yielded some surprises; not, least, a belated explanation for an apparent anomaly encountered in 1987, when a mixture of oxygen and sulphur ions was accelerated in the CERN Proton Synchrotron for the first time. These ideas are supported by measurements performed in 1990 during a second ion run

Present and future sources of protons and heavy ions

International Nuclear Information System (INIS)

Grunder, H.A.; Leemann, C.W.

1976-01-01

A brief outline of existing medical heavy-ion facilities is given. The beam specifications for future dedicated medical ion accelerators are discussed. Machines capable of delivering dose rates of approximately 1 krad/min in volumes of a few liters are shown to represent existing technology. A cost and performance analysis shows the synchrotrons to be the most economical source for the heavier ions while conventional cyclotrons seem optimal for an exclusive proton facility. It is seen that the incorporation of additional capabilities such as neutron generation or radioisotope production can be achieved at modest incremental costs. In addition to the accelerators, feasible layouts of hypothetical facilities are discussed, and three-dimensional beam scanning is shown to allow the irradiation of large volumes without sacrificing the precise dose localization capabilities of heavy-ion beams. Concepts of quality-controlled engineering and modern computer technology are introduced as a means to obtain the desired high degree of reliability and ease of operation and maintenance

Sorption of Molecular Oxygen by Metal-Ion Exchanger Nanocomposites

Science.gov (United States)

Krysanov, V. A.; Plotnikova, N. V.; Kravchenko, T. A.

2018-03-01

Kinetic features are studied of the chemisorption and reduction of molecular oxygen from water by metal-ion exchanger nanocomposites that differ in the nature of the dispersed metal and state of oxidation. In the Pd equilibrium sorption coefficient for oxygen dissolved in water ranges from 20 to 50, depending on the nature and oxidation state of the metal component.

Facilitated ion transfer of protonated primary organic amines studied by square wave voltammetry and chronoamperometry

Energy Technology Data Exchange (ETDEWEB)

Torralba, E. [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Ortuño, J.A. [Departamento de Química Analítica, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Molina, A., E-mail: amolina@um.es [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Serna, C. [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Karimian, F. [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2014-05-01

Highlights: • Facilitated ion transfer of organic protonated amines is studied. • Cyclic square wave voltammetry is used as main technique. • Complexation constants and standard ion transfer potentials are determined. • Diffusion coefficients in the organic and aqueous phases are determined. • The goodness of square wave voltammetry as analytical tool is shown. - Abstract: The transfer of the protonated forms of heptylamine, octylamine, decylamine, procaine and procainamide facilitated by dibenzo-18-crown-6 from water to a solvent polymeric membrane has been investigated by using cyclic square wave voltammetry. The experimental voltammograms obtained are in good agreement with theoretical predictions. The values of the standard ion transfer potential, complexation constant and diffusion coefficient in water have been obtained from these experiments, and have been used to draw some conclusions about the lipophilicity of these species and the relative stability of the organic ammonium complexes with dibenzo-18-crown-6. The results have been compared with those provided by linear sweep voltammetry. Calibration graphs were obtained with both techniques. An interesting chronoamperometric method for the determination of the diffusion coefficient of the target ion in the membrane has been developed and applied to all these protonated amines.

A Deterministic Electron, Photon, Proton and Heavy Ion Radiation Transport Suite for the Study of the Jovian System

Science.gov (United States)

Norman, Ryan B.; Badavi, Francis F.; Blattnig, Steve R.; Atwell, William

2011-01-01

A deterministic suite of radiation transport codes, developed at NASA Langley Research Center (LaRC), which describe the transport of electrons, photons, protons, and heavy ions in condensed media is used to simulate exposures from spectral distributions typical of electrons, protons and carbon-oxygen-sulfur (C-O-S) trapped heavy ions in the Jovian radiation environment. The particle transport suite consists of a coupled electron and photon deterministic transport algorithm (CEPTRN) and a coupled light particle and heavy ion deterministic transport algorithm (HZETRN). The primary purpose for the development of the transport suite is to provide a means for the spacecraft design community to rapidly perform numerous repetitive calculations essential for electron, proton and heavy ion radiation exposure assessments in complex space structures. In this paper, the radiation environment of the Galilean satellite Europa is used as a representative boundary condition to show the capabilities of the transport suite. While the transport suite can directly access the output electron spectra of the Jovian environment as generated by the Jet Propulsion Laboratory (JPL) Galileo Interim Radiation Electron (GIRE) model of 2003; for the sake of relevance to the upcoming Europa Jupiter System Mission (EJSM), the 105 days at Europa mission fluence energy spectra provided by JPL is used to produce the corresponding dose-depth curve in silicon behind an aluminum shield of 100 mils ( 0.7 g/sq cm). The transport suite can also accept ray-traced thickness files from a computer-aided design (CAD) package and calculate the total ionizing dose (TID) at a specific target point. In that regard, using a low-fidelity CAD model of the Galileo probe, the transport suite was verified by comparing with Monte Carlo (MC) simulations for orbits JOI--J35 of the Galileo extended mission (1996-2001). For the upcoming EJSM mission with a potential launch date of 2020, the transport suite is used to compute

Time required for partial pressure of arterial oxygen equilibration during mechanical ventilation after a step change in fractional inspired oxygen concentration.

Science.gov (United States)

Cakar, N; Tuŏrul, M; Demirarslan, A; Nahum, A; Adams, A; Akýncý, O; Esen, F; Telci, L

2001-04-01

To determine the time required for the partial pressure of arterial oxygen (PaO2) to reach equilibrium after a 0.20 increment or decrement in fractional inspired oxygen concentration (FIO2) during mechanical ventilation. A multi-disciplinary ICU in a university hospital. Twenty-five adult, non-COPD patients with stable blood gas values (PaO2/FIO2 > or = 180 on the day of the study) on pressure-controlled ventilation (PCV). Following a baseline PaO2 (PaO2b) measurement at FIO2 = 0.35, the FIO2 was increased to 0.55 for 30 min and then decreased to 0.35 without any other change in ventilatory parameters. Sequential blood gas measurements were performed at 3, 5, 7, 9, 11, 15, 20, 25 and 30 min in both periods. The PaO2 values measured at the 30th min after a step change in FIO2 (FIO2 = 0.55, PaO2[55] and FIO2 = 0.35, PaO2[35]) were accepted as representative of the equilibrium values for PaO2. Each patient's rise and fall in PaO2 over time, PaO2(t), were fitted to the following respective exponential equations: PaO2b + (PaO2[55]-PaO2b)(1-e-kt) and PaO2[55] + (PaO2[35]-PaO2[55])(e-kt) where "t" refers to time, PaO2[55] and PaO2[35] are the final PaO2 values obtained at a new FIO2 of 0.55 and 0.35, after a 0.20 increment and decrement in FIO2, respectively. Time constant "k" was determined by a non-linear fitting curve and 90% oxygenation times were defined as the time required to reach 90% of the final equilibrated PaO2 calculated by using the non-linear fitting curves. Time constant values for the rise and fall periods were 1.01 +/- 0.71 min-1, 0.69 +/- 0.42 min-1, respectively, and 90% oxygenation times for rises and falls in PaO2 periods were 4.2 +/- 4.1 min-1 and 5.5 +/- 4.8 min-1, respectively. There was no significant difference between the rise and fall periods for the two parameters (p > 0.05). We conclude that in stable patients ventilated with PCV, after a step change in FIO2 of 0.20, 5-10 min will be adequate for obtaining a blood gas sample to measure a Pa

Equilibration Influence on Jet Energy Loss

International Nuclear Information System (INIS)

Cheng Luan; Wang Enke

2010-01-01

With the initial conditions in the chemical non-equilibrated medium and Bjorken expanding medium at RHIC, we investigate the consequence for parton evolution. With considering the parton equilibration, we obtain the time dependence of the opacity when the jet propagates through the QGP medium. The parton equilibration affect the jet energy loss with detailed balance evidently. Both parton energy loss from stimulated emission in the chemical non-equilibrated expanding medium and in Bjorken expanding medium are linear dependent on the propagating distance rather than square dependent in the static medium. This will increase the energy and propagating distance dependence of the parton energy loss.

Comparative results on collimation of the SPS beam of protons and Pb ions with bent crystals

CERN Document Server

Scandale, W.; Assmann, R.; Bracco, C.; Cerutti, F.; Christiansen, J.; Gilardoni, S.; Laface, E.; Losito, R.; Masi, A.; Metral, E.; Mirarchi, D.; Montesano, S.; Previtali, V.; Redaelli, S.; Valentino, G.; Schoofs, P.; Smirnov, G.; Tlustos, L.; Bagli, E.; Baricordi, S.; Dalpiaz, P.; Guidi, V.; Mazzolari, A.; Vincenzi, D.; Dabagov, S.; Murtas, F.; Carnera, A.; Della Mea, G.; De Salvador, D.; Lombardi, A.; Lytovchenko, O.; Tonezzer, M.; Cavoto, G.; Ludovici, L.; Santacesaria, R.; Valente, P.; Galluccio, F.; Afonin, A.G.; Bulgakov, M.K.; Chesnokov, Yu.A.; Maisheev, V.A.; Yazynin, I.A.; Kovalenko, A.D.; Taratin, A.M.; Uzhinskiy, V.V.; Gavrikov, Yu.A.; Ivanov, Yu.M.; Lapina, L.P.; Skorobogatov, V.V.; Ferguson, W.; Fulcher, J.; Hall, G.; Pesaresi, M.; Raymond, M.; Rose, A.; Ryan, M.; Zorba, O.; Robert-Demolaize, G.; Markiewicz, T.; Oriunno, M.; Wienands, U.

2011-01-01

New experiments on crystal assisted collimation have been carried out at the CERN SPS with stored beams of 120 Gev/c protons and Pb ions. Bent silicon crystals of 2 mm long with about 170 mu rad bend angle and a small residual torsion were used as primary collimators. In channeling conditions, the beam loss rate induced by inelastic interactions of particles with the crystal nuclei is minimal. The loss reduction was about 6 for protons and about 3 for Pb ions. Lower reduction value for Pb ions can be explained by their considerably larger ionization losses in the crystal. In one of the crystals, the measured fraction of the Pb ion beam halo deflected in channeling conditions was 74\\%, a value very close to that for protons. The intensity of the off-momentum halo leaking out from the collimation station was measured in the first high dispersion area downstream. The particle population in the shadow of the secondary collimator-absorber was considerably smaller in channeling conditions than for amorphous orienta...

Deamidation reactions of protonated asparagine and glutamine investigated by ion spectroscopy

NARCIS (Netherlands)

Kempkes, L.J.M.; Martens, J.K.; Grzetic, J.; Berden, G.; Oomens, J.

2016-01-01

RATIONALE: Deamidation of Asn and Gln residues is a primary route for spontaneous post-translational protein modification. Several structures have been proposed for the deamidation products of the protonated amino acids. Here we verify these structures by ion spectroscopy, as well as the structures

A deterministic electron, photon, proton and heavy ion transport suite for the study of the Jovian moon Europa

International Nuclear Information System (INIS)

Badavi, Francis F.; Blattnig, Steve R.; Atwell, William; Nealy, John E.; Norman, Ryan B.

2011-01-01

A Langley research center (LaRC) developed deterministic suite of radiation transport codes describing the propagation of electron, photon, proton and heavy ion in condensed media is used to simulate the exposure from the spectral distribution of the aforementioned particles in the Jovian radiation environment. Based on the measurements by the Galileo probe (1995-2003) heavy ion counter (HIC), the choice of trapped heavy ions is limited to carbon, oxygen and sulfur (COS). The deterministic particle transport suite consists of a coupled electron photon algorithm (CEPTRN) and a coupled light heavy ion algorithm (HZETRN). The primary purpose for the development of the transport suite is to provide a means to the spacecraft design community to rapidly perform numerous repetitive calculations essential for electron, photon, proton and heavy ion exposure assessment in a complex space structure. In this paper, the reference radiation environment of the Galilean satellite Europa is used as a representative boundary condition to show the capabilities of the transport suite. While the transport suite can directly access the output electron and proton spectra of the Jovian environment as generated by the jet propulsion laboratory (JPL) Galileo interim radiation electron (GIRE) model of 2003; for the sake of relevance to the upcoming Europa Jupiter system mission (EJSM), the JPL provided Europa mission fluence spectrum, is used to produce the corresponding depth dose curve in silicon behind a default aluminum shield of 100 mils (∼0.7 g/cm 2 ). The transport suite can also accept a geometry describing ray traced thickness file from a computer aided design (CAD) package and calculate the total ionizing dose (TID) at a specific target point within the interior of the vehicle. In that regard, using a low fidelity CAD model of the Galileo probe generated by the authors, the transport suite was verified versus Monte Carlo (MC) simulation for orbits JOI-J35 of the Galileo probe

Study of forward physics in sqrt(s_NN) = 8.1 TeV proton-Lead ion collisions with the LHCf detector at the LHC

CERN Document Server

Adriani, O; Bonechi, L; Bongi, M; Castellini, G; D'Alessandro, R; Haguenauer, M; Itow, Y; Iwata, T; Kasahara, K; Makino, Y; Masuda, K; Matsubayashi, E; Matsubara, Y; Menjo, H; Muraki, Y; Okuno, Y; Papini, P; Ricciarini, S; Sako, T; Sakurai, N; Suzuki, T; Shimizu, Y; Tamura, T; Tiberio, A; Torii, S; Tricomi, A; Turner, WC; Ueno, M; Yoshida, K; Zhou, QD; CERN. Geneva. The LHC experiments Committee; LHCC

2016-01-01

The LHCf detectors were installed for the first time in the TAN regions on both sides of IP1 at the beginning of the LHC run in 2009. The goal of the experiment is the measurement of neutral particle production at very high pseudo-rapidity values (eta > 8.4) in proton-proton (p+p) and proton-ion (p+A) collisions. Until now the experiment has achieved successful measurements for p+p collisions at sqrt(s) =900 GeV, 2.78 TeV, 7 TeV and 13 TeV and for p+Pb collision at sqrt(s_NN) = 5.0 TeV. These data will be extremely useful in the near future for the calibration of hadronic interaction models that are commonly used for the study of the development of Extensive Air Showers (EAS) produced by extremely energetic cosmic-rays (CR) interacting with the atmospheric gas. Even though the most frequent collisions of cosmic ray protons in atmosphere involve mainly nitrogen and oxygen nuclei, the study of both the p+p and p+Pb systems at the LHC allows providing important information for the calibration of hadronic interac...

The foil equilibration method for carbon in sodium

Energy Technology Data Exchange (ETDEWEB)

Borgstedt, H; Frees, G; Peric, Z [Karlsruhe Nuclear Research Center, Institute of Materials and Solid State Research, Karlsruhe (Germany)

1980-05-01

Among the non-metallic impurities in sodium, carbon plays an important role since at high temperatures the structural materials exposed to sodium are subject to carburization and decarburization depending on the carbon activity of the sodium. Carburization of austenitic stainless steels leads to reduction in ductility and fatigue properties whereas decarburization results in a decrease in the high temperature creep strength. A knowledge of the carbon activities in sodium will help understanding of the carbon transfer phenomena in operating sodium systems of the fast reactors, and also carbon diffusion, microstructural stability and mechanical behaviour of materials under different service conditions. An understanding of the carbon behaviour in sodium becomes difficult in view of the complexities of the different species present as elemental carbon, carbide, acetylide, carbonate, and cyanide. Carbon estimation techniques for sodium presently in use are: chemical analytical methods, on-line carbon monitors, and oil equilibration method. Various chemical methods have been developed for the estimation of different species like acetylide, cyanide, carbonate, elemental carbon, and total carbon in sodium. All these methods are time consuming and subject to various errors. The on-line monitors developed for carbon in sodium are able to give continuous indication of carbon activities and have higher sensitivity than the chemical methods. A still more simple method for the determination of carbon activities is by the foil equilibration first published by Natesan et al. Because of its simplicity like the vanadium wire equilibration for oxygen it is being used widely for the estimation of carbon activities in sodium systems. Carbon concentrations in operating sodium systems estimated by this procedure by applying solubility relation to carbon activities have yielded very low values of carbon, lower than the sensitivity limits of the chemical estimation methods. Foil

The foil equilibration method for carbon in sodium

International Nuclear Information System (INIS)

Borgstedt, H.; Frees, G.; Peric, Z.

1980-01-01

Among the non-metallic impurities in sodium, carbon plays an important role since at high temperatures the structural materials exposed to sodium are subject to carburization and decarburization depending on the carbon activity of the sodium. Carburization of austenitic stainless steels leads to reduction in ductility and fatigue properties whereas decarburization results in a decrease in the high temperature creep strength. A knowledge of the carbon activities in sodium will help understanding of the carbon transfer phenomena in operating sodium systems of the fast reactors, and also carbon diffusion, microstructural stability and mechanical behaviour of materials under different service conditions. An understanding of the carbon behaviour in sodium becomes difficult in view of the complexities of the different species present as elemental carbon, carbide, acetylide, carbonate, and cyanide. Carbon estimation techniques for sodium presently in use are: chemical analytical methods, on-line carbon monitors, and oil equilibration method. Various chemical methods have been developed for the estimation of different species like acetylide, cyanide, carbonate, elemental carbon, and total carbon in sodium. All these methods are time consuming and subject to various errors. The on-line monitors developed for carbon in sodium are able to give continuous indication of carbon activities and have higher sensitivity than the chemical methods. A still more simple method for the determination of carbon activities is by the foil equilibration first published by Natesan et al. Because of its simplicity like the vanadium wire equilibration for oxygen it is being used widely for the estimation of carbon activities in sodium systems. Carbon concentrations in operating sodium systems estimated by this procedure by applying solubility relation to carbon activities have yielded very low values of carbon, lower than the sensitivity limits of the chemical estimation methods. Foil

Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

Energy Technology Data Exchange (ETDEWEB)

Catapano, Filomena; Zimbardo, Gaetano; Perri, Silvia; Greco, Antonella [Calabria Univ., Rende (Italy). Dept. of Physics; Artemyev, Anton V. [Russian Academy of Science, Moscow (Russian Federation). Space Research Inst.; California Univ., Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Science and Inst. of Geophysics and Planetary Physics

2016-07-01

Spacecraft observations show that energetic ions are found in the Earth's magnetotail, with energies ranging from tens of keV to a few hundreds of keV. In this paper we carry out test particle simulations in which protons and other ion species are injected in the Vlasov magnetic field configurations obtained by Catapano et al. (2015). These configurations represent solutions of a generalized Harris model, which well describes the observed profiles in the magnetotail. In addition, three-dimensional time-dependent stochastic electromagnetic perturbations are included in the simulation box, so that the ion acceleration process is studied while varying the equilibrium magnetic field profile and the ion species. We find that proton energies of the order of 100 keV are reached with simulation parameters typical of the Earth's magnetotail. By changing the ion mass and charge, we can study the acceleration of heavy ions such as He{sup ++} and O{sup +}, and it is found that energies of the order of 100-200 keV are reached in a few seconds for He{sup ++}, and about 100 keV for O{sup +}.

Helium Ion Microscopy of proton exchange membrane fuel cell electrode structures

DEFF Research Database (Denmark)

Chiriaev, Serguei; Dam Madsen, Nis; Rubahn, Horst-Günter

2017-01-01

electrode interface structure dependence on ionomer content, systematically studied by Helium Ion Microscopy (HIM). A special focus was on acquiring high resolution images of the electrode structure and avoiding interface damage from irradiation and tedious sample preparation. HIM demonstrated its....... In the hot-pressed electrodes, we found more closed contact between the electrode components, reduced particle size, polymer coalescence and formation of nano-sized polymer fiber architecture between the particles. Keywords: proton exchange membrane fuel cells (PEMFCs); Helium Ion Microscopy (HIM...

Theoretical ion implantation profiles for low energy protons under channeling conditions

International Nuclear Information System (INIS)

Nobel, J.A.; Sabin, J.R.; Trickey, S.B.

1994-01-01

The authors present early results from the CHANNEL code, which simulates the passage of ionized projectiles through bulk solids. CHANNEL solves the classical equations of motion for the projectile using a force obtained from the gradient of the quantum mechanically derived coulombic potential of the solid (determined via a full potential augmented plane wave (FLAPW) calculation on the bulk) and a quantum mechanical energy dissipation term, the stopping power, as determined from the method of Echenique, Neiminen, and Ritchie. The code then generates the trajectory of the ionic projectile for a given incident position on the unit cell face and an initial velocity. The authors use CHANNEL to generate an ion (proton) implantation profile for the test case of simple cubic hydrogen with the projectile's initial velocity parallel to the (100) channel. Further preliminary results for ion implantation profiles of protons in diamond structure Si, with initial velocity along the (100) and (110) channels, are given

Proton solvation and proton transfer in chemical and electrochemical processes

International Nuclear Information System (INIS)

Lengyel, S.; Conway, B.E.

1983-01-01

This chapter examines the proton solvation and characterization of the H 3 O + ion, proton transfer in chemical ionization processes in solution, continuous proton transfer in conductance processes, and proton transfer in electrode processes. Topics considered include the condition of the proton in solution, the molecular structure of the H 3 O + ion, thermodynamics of proton solvation, overall hydration energy of the proton, hydration of H 3 O + , deuteron solvation, partial molal entropy and volume and the entropy of proton hydration, proton solvation in alcoholic solutions, analogies to electrons in semiconductors, continuous proton transfer in conductance, definition and phenomenology of the unusual mobility of the proton in solution, solvent structure changes in relation to anomalous proton mobility, the kinetics of the proton-transfer event, theories of abnormal proton conductance, and the general theory of the contribution of transfer reactions to overall transport processes

Formation of Pyrylium from Aromatic Systems with a Helium:Oxygen Flowing Atmospheric Pressure Afterglow (FAPA) Plasma Source

Science.gov (United States)

Badal, Sunil P.; Ratcliff, Tyree D.; You, Yi; Breneman, Curt M.; Shelley, Jacob T.

2017-06-01

The effects of oxygen addition on a helium-based flowing atmospheric pressure afterglow (FAPA) ionization source are explored. Small amounts of oxygen doped into the helium discharge gas resulted in an increase in abundance of protonated water clusters by at least three times. A corresponding increase in protonated analyte signal was also observed for small polar analytes, such as methanol and acetone. Meanwhile, most other reagent ions (e.g., O2 +·, NO+, etc.) significantly decrease in abundance with even 0.1% v/v oxygen in the discharge gas. Interestingly, when analytes that contained aromatic constituents were subjected to a He:O2-FAPA, a unique (M + 3)+ ion resulted, while molecular or protonated molecular ions were rarely detected. Exact-mass measurements revealed that these (M + 3)+ ions correspond to (M - CH + O)+, with the most likely structure being pyrylium. Presence of pyrylium-based ions was further confirmed by tandem mass spectrometry of the (M + 3)+ ion compared with that of a commercially available salt. Lastly, rapid and efficient production of pyrylium in the gas phase was used to convert benzene into pyridine. Though this pyrylium-formation reaction has not been shown before, the reaction is rapid and efficient. Potential reactant species, which could lead to pyrylium formation, were determined from reagent-ion mass spectra. Thermodynamic evaluation of reaction pathways was aided by calculation of the formation enthalpy for pyrylium, which was found to be 689.8 kJ/mol. Based on these results, we propose that this reaction is initiated by ionized ozone (O3 +·), proceeds similarly to ozonolysis, and results in the neutral loss of the stable CHO2 · radical. [Figure not available: see fulltext.

Oxygen sensor using proton-conductor thick-film operative at room temperature. Puroton dodentai atsumaku wo mochiita joon sadogata sanso sensor

Energy Technology Data Exchange (ETDEWEB)

Miura, Norio; Yoshida, Nobuaki; Matayoshi, Naoko; Shimizu, Yoichi; Yamazoe, Noboru; Kuwata, Shigeki [Kyushu Univ., Fukuoka, (Japan) Niihama National College of Tech., Ehime, (Japan)

1989-10-01

An amperometric solid-state oxygen sensor using a proton-conductor thick-film was examined as a miniaturized and intelligent oxygen sensor operative at room temperature. The good-conditioned proton-conductor film of about 10{mu}m in thickness without holes was formed on a porous alumina substrate by spin-coating the paste containing antimonic acid and a polyvinyl alcohol binder. Using this material, the thick-film oxygen sensor was made. A limiting current, controlled by oxygen permeation through the gas-diffusion layer, was observed when an external voltage was over 1.4V. The limiting current increased linearly with an increase in oxygen partial pressure up to 1.0 atm at an external voltage of 1.6V. The 90% response time for increasing oxygen partial pressure was about 40 seconds at 30 centigrade. Moreover, it was found that the sensor could also respond to dissolved oxygen in water at room temperature. With a sensor using a hydrophobic gas-diffusion layer containing a polystyrene binder, the limiting current was linear to the dissolved oxygen concentration up to 20ppm. 15 refs., 5 figs.

FTIR studies of swift silicon and oxygen ion irradiated porous silicon

International Nuclear Information System (INIS)

Bhave, Tejashree M.; Hullavarad, S.S.; Bhoraskar, S.V.; Hegde, S.G.; Kanjilal, D.

1999-01-01

Fourier Transform Infrared Spectroscopy has been used to study the bond restructuring in silicon and oxygen irradiated porous silicon. Boron doped p-type (1 1 1) porous silicon was irradiated with 10 MeV silicon and a 14 MeV oxygen ions at different doses ranging between 10 12 and 10 14 ions cm -2 . The yield of PL in porous silicon irradiated samples was observed to increase considerably while in oxygen irradiated samples it was seen to improve only by a small extent for lower doses whereas it decreased for higher doses. The results were interpreted in view of the relative intensities of the absorption peaks associated with O-Si-H and Si-H stretch bonds

Reduction by metals dissolved in liquid ammonia of keto steroids. Equilibration of the alcohols; Reduction par les metaux dissous dans l'ammoniac liquide de cetones en serie steroide. Equilibration des alcools

Energy Technology Data Exchange (ETDEWEB)

Giroud, A M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1970-07-01

Reducing a ketone by dissolved metals involves two electrons; we may consider as intermediate a radical-anion, then a di-anion or a carbo-anion. The radical-anion may also split and give pinacols away. In order to discuss the reduction proceeds, we had to know the respective stabilities of the alcohols, which lead us to effectuate equilibration. The first chapter is devoted to the method of preparing the androstanone-II and the androstanols-II{alpha} and II-{beta}. We further establish the impossibility of using our methods for reaching a conclusion about the alcohols relative stability by experimental equilibration. Last we describe the methods for reducing the ketone by alkaline and earth-alkaline metals, dissolved in liquid ammonia, either in contact with a protons donor or with a later added protons donor. The resulting mixture of the two alcohols shows a prevailing quantity of the stable equatorial isomer {alpha}. In a second chapter, we study the action of selenic acid and hydroperoxide on cholestanone-3, which leads us to study the preparation and stereochemistry of the A-nor cholestane derivates. We further describe the preparation of the A-nor cholestanols-2{alpha} and 2{beta}, and the corresponding acetates. Equilibration of the alcohols by chemical methods shows the 2 {alpha}-alcohol more stable than the 2{beta}, which is mathematically confirmed. Last, the reduction of the A-nor cholestanone-2 by dissolved metals consistently leads to the less stable 2 {beta} epimer, with associated pinacols. The third chapter is devoted to the study of the androstanone-17 reductions, and the relative stabilities of the 17{alpha} and 17{beta} alcohols. Whichever operating methods is used, we predominantly obtain the more stable 17{beta} alcohol. In all cases, a pinacol production is observed. Summing up, we note that, in all cases, we predominantly obtain the equatorial epimer, whether it should be the more stable or the less stable. (author) [French] La reduction d

Laser-ablation-based ion source characterization and manipulation for laser-driven ion acceleration

Science.gov (United States)

Sommer, P.; Metzkes-Ng, J.; Brack, F.-E.; Cowan, T. E.; Kraft, S. D.; Obst, L.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

2018-05-01

For laser-driven ion acceleration from thin foils (∼10 μm–100 nm) in the target normal sheath acceleration regime, the hydro-carbon contaminant layer at the target surface generally serves as the ion source and hence determines the accelerated ion species, i.e. mainly protons, carbon and oxygen ions. The specific characteristics of the source layer—thickness and relevant lateral extent—as well as its manipulation have both been investigated since the first experiments on laser-driven ion acceleration using a variety of techniques from direct source imaging to knife-edge or mesh imaging. In this publication, we present an experimental study in which laser ablation in two fluence regimes (low: F ∼ 0.6 J cm‑2, high: F ∼ 4 J cm‑2) was applied to characterize and manipulate the hydro-carbon source layer. The high-fluence ablation in combination with a timed laser pulse for particle acceleration allowed for an estimation of the relevant source layer thickness for proton acceleration. Moreover, from these data and independently from the low-fluence regime, the lateral extent of the ion source layer became accessible.

Visible-light activate Ag/WO3 films based on wood with enhanced negative oxygen ions production properties

Science.gov (United States)

Gao, Likun; Gan, Wentao; Cao, Guoliang; Zhan, Xianxu; Qiang, Tiangang; Li, Jian

2017-12-01

The Ag/WO3-wood was fabricated through a hydrothermal method and a silver mirror reaction. The system of visible-light activate Ag/WO3-wood was used to produce negative oxygen ions, and the effect of Ag nanoparticles on negative oxygen ions production was investigated. From the results of negative oxygen ions production tests, it can be observed that the sample doped with Ag nanoparticles, the concentration of negative oxygen ions is up to 1660 ions/cm3 after 60 min visible light irradiation. Moreover, for the Ag/WO3-wood, even after 60 min without irradiation, the concentration of negative oxygen ions could keep more than 1000 ions/cm3, which is up to the standard of the fresh air. Moreover, due to the porous structure of wood, the wood acted as substrate could promote the nucleation of nanoparticles, prevent the agglomeration of the particles, and thus lead the improvement of photocatalytic properties. And such wood-based functional materials with the property of negative oxygen ions production could be one of the most promising materials in the application of indoor decoration materials, which would meet people's pursuit of healthy, environment-friendly life.

Inactivation of Bacillus atrophaeus and of Aspergillus niger using beams of argon ions, of oxygen molecules and of oxygen atoms

Energy Technology Data Exchange (ETDEWEB)

Raballand, V; Benedikt, J; Keudell, A von [Research Group Reactive Plasmas, Ruhr-Universitaet Bochum, 44780 Bochum (Germany); Wunderlich, J [Fraunhofer Institut for Process Engineering and Packaging, Giggenhauser Strasse 35, 85354 Freising (Germany)], E-mail: Achim.vonKeudell@rub.de

2008-06-07

The inactivation of spores of Bacillus atrophaeus and of Aspergillus niger using beams of argon ions, of oxygen molecules and of oxygen atoms is studied. Thereby, the conditions occurring in oxygen containing low pressure plasmas are mimicked and fundamental inactivation mechanisms can be revealed. It is shown that the impact of O atoms has no effect on the viability of the spores and that no etching of the spore coat occurs up to an O atom fluence of 3.5 x 10{sup 19} cm{sup -2}. The impact of argon ions with an energy of 200 eV does not cause significant erosion for fluences up to 1.15 x 10{sup 18} cm{sup -2}. However, the combined impact of argon ions and oxygen molecules or atoms causes significant etching of the spores and significant inactivation. This is explained by the process of chemical sputtering, where an ion-induced defect at the surface of the spore reacts with either the incident bi-radical O{sub 2} or with an incident O atom. This leads to the formation of CO, CO{sub 2} and H{sub 2}O and thus to erosion.

Protons and heavy ions induced stuck bits on large capacity RAMs

Energy Technology Data Exchange (ETDEWEB)

Duzellier, S; Falguere, D; Ecoffet, R [Centre National d` Etudes Spatiales (CNES), 31 - Toulouse (France)

1994-12-31

A semi-permanent imprint effect has been observed, on large capacity memories (static and dynamic), during heavy ion and proton irradiations. The experimental circumstances of stuck bits occurrence are described and the influence of irradiation conditions discussed. A total dose testing complete the investigation. (author). 10 refs., 5 figs., 3 tabs.

Simulation and dosimetric analysis of protons, 4He ions and 12C ions beams for brain neoplasm therapy

International Nuclear Information System (INIS)

Santos, Guilherme M.; Mello, Victor Barreto Braga; Mello Neto, Joao R.T. de

2016-01-01

This study aims to simulate protons, 4 He ions and 12 C ions beams, radiating the head of an average-sized man with the purpose of treating a hypothalamic tumor. GEANT4 was used to simulate the head (skin, skull and brain), and the beam, giving their characteristics and also the physical processes involved. The results sought herein are graphs of depth for relative dose for each of the three particles incident on the settings mentioned above. (author)

Reduction by metals dissolved in liquid ammonia of keto steroids. Equilibration of the alcohols; Reduction par les metaux dissous dans l'ammoniac liquide de cetones en serie steroide. Equilibration des alcools

Energy Technology Data Exchange (ETDEWEB)

Giroud, A.M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1970-07-01

Reducing a ketone by dissolved metals involves two electrons; we may consider as intermediate a radical-anion, then a di-anion or a carbo-anion. The radical-anion may also split and give pinacols away. In order to discuss the reduction proceeds, we had to know the respective stabilities of the alcohols, which lead us to effectuate equilibration. The first chapter is devoted to the method of preparing the androstanone-II and the androstanols-II{alpha} and II-{beta}. We further establish the impossibility of using our methods for reaching a conclusion about the alcohols relative stability by experimental equilibration. Last we describe the methods for reducing the ketone by alkaline and earth-alkaline metals, dissolved in liquid ammonia, either in contact with a protons donor or with a later added protons donor. The resulting mixture of the two alcohols shows a prevailing quantity of the stable equatorial isomer {alpha}. In a second chapter, we study the action of selenic acid and hydroperoxide on cholestanone-3, which leads us to study the preparation and stereochemistry of the A-nor cholestane derivates. We further describe the preparation of the A-nor cholestanols-2{alpha} and 2{beta}, and the corresponding acetates. Equilibration of the alcohols by chemical methods shows the 2 {alpha}-alcohol more stable than the 2{beta}, which is mathematically confirmed. Last, the reduction of the A-nor cholestanone-2 by dissolved metals consistently leads to the less stable 2 {beta} epimer, with associated pinacols. The third chapter is devoted to the study of the androstanone-17 reductions, and the relative stabilities of the 17{alpha} and 17{beta} alcohols. Whichever operating methods is used, we predominantly obtain the more stable 17{beta} alcohol. In all cases, a pinacol production is observed. Summing up, we note that, in all cases, we predominantly obtain the equatorial epimer, whether it should be the more stable or the less stable. (author) [French] La reduction d

TECHNOLOGIES FOR DELIVERY OF PROTON AND ION BEAMS FOR RADIOTHERAPY

CERN Document Server

Owen, H; Alonso, J; Mackay, R

2014-01-01

Recent developments for the delivery of proton and ion beam therapy have been significant, and a number of technological solutions now exist for the creation and utilisation of these particles for the treatment of cancer. In this paper we review the historical development of particle accelerators used for external beam radiotherapy and discuss the more recent progress towards more capable and cost-effective sources of particles.

Migration of interfacial oxygen ions modulated resistive switching in oxide-based memory devices

Science.gov (United States)

Chen, C.; Gao, S.; Zeng, F.; Tang, G. S.; Li, S. Z.; Song, C.; Fu, H. D.; Pan, F.

2013-07-01

Oxides-based resistive switching memory induced by oxygen ions migration is attractive for future nonvolatile memories. Numerous works had focused their attentions on the sandwiched oxide materials for depressing the characteristic variations, but the comprehensive studies of the dependence of electrodes on the migration behavior of oxygen ions are overshadowed. Here, we investigated the interaction of various metals (Ni, Co, Al, Ti, Zr, and Hf) with oxygen atoms at the metal/Ta2O5 interface under electric stress and explored the effect of top electrode on the characteristic variations of Ta2O5-based memory device. It is demonstrated that chemically inert electrodes (Ni and Co) lead to the scattering switching characteristics and destructive gas bubbles, while the highly chemically active metals (Hf and Zr) formed a thick and dense interfacial intermediate oxide layer at the metal/Ta2O5 interface, which also degraded the resistive switching behavior. The relatively chemically active metals (Al and Ti) can absorb oxygen ions from the Ta2O5 film and avoid forming the problematic interfacial layer, which is benefit to the formation of oxygen vacancies composed conduction filaments in Ta2O5 film thus exhibit the minimum variations of switching characteristics. The clarification of oxygen ions migration behavior at the interface can lead further optimization of resistive switching performance in Ta2O5-based memory device and guide the rule of electrode selection for other oxide-based resistive switching memories.

Oxygen potential of uranium--plutonium oxide as determined by controlled-atmosphere thermogravimetry

International Nuclear Information System (INIS)

Swanson, G.C.

1975-10-01

The oxygen-to-metal atom ratio, or O/M, of solid solution uranium-plutonium oxide reactor fuel is a measure of the concentration of crystal defects in the oxide which affect many fuel properties, particularly, fuel oxygen potential. Fabrication of a high-temperature oxygen electrode, employing an electro-active tip of oxygen-deficient solid-state electrolyte, intended to confirm gaseous oxygen potentials is described. Uranium oxide and plutonium oxide O/M reference materials were prepared by in situ oxidation of high purity metals in the thermobalance. A solid solution uranium-plutonium oxide O/M reference material was prepared by alloying the uranium and plutonium metals in a yttrium oxide crucible at 1200 0 C and oxidizing with moist He at 250 0 C. The individual and solid solution oxides were isothermally equilibrated with controlled oxygen potentials between 800 and 1300 0 C and the equilibrated O/M ratios calculated with corrections for impurities and buoyancy effects. Use of a reference oxygen potential of -100 kcal/mol to produce an O/M of 2.000 is confirmed by these results. However, because of the lengthy equilibration times required for all oxides, use of the O/M reference materials rather than a reference oxygen potential is recommended for O/M analysis methods calibrations. (auth)

Physico-chemical modification of polyethersulphone induced by high energy proton, C+ and Ne6+ ions

International Nuclear Information System (INIS)

Vinodh Kumar, S.; Biswavarathi, V.; Jal, P.; Dey, K.; Krishna, J.B.M.; Saha, A.

2004-01-01

Polyehersulphone (PES) was irradiated with 4 MeV proton, 3.6 MeV C + and 145 MeV Ne 6+ ions at different ion fluences. The ion induced spectral changes were analyzed by UV-visible and fluorescence spectroscopy. The increase in optical absorption, which shifts gradually from near UV to the visible region with increase in fluence for the three different types of bombarding ions was observed. A significant loss in fluorescence intensity with increase in fluence for three different ions was observed. (author)

Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

Energy Technology Data Exchange (ETDEWEB)

Briggs, Samuel A., E-mail: sabriggs2@wisc.edu [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Barr, Christopher M. [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Pakarinen, Janne [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); SKC-CEN Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium); Mamivand, Mahmood [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Hattar, Khalid [Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 (United States); Morgan, Dane D. [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Taheri, Mitra [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Sridharan, Kumar [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States)

2016-10-15

Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni{sup 4+} ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy. - Highlights: • Binary Ni-Cr alloys were irradiated with protons or Ni ions at 400 and 500 °C. • Higher irradiation temperatures yield increased size, decreased density of defects. • Hypothesize that varying Cr content affects interstitial binding energy. • Fitting CD models for loop nucleation to data supports this hypothesis.

Oxygen ion transference number of doped lanthanum gallate

Science.gov (United States)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong; Liu, Meilin

The transference numbers for oxygen ion (t O) in several LaGaO 3-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications.

Acceleration of polarized protons and deuterons in the ion collider ring of JLEIC

Science.gov (United States)

Kondratenko, A. M.; Kondratenko, M. A.; Filatov, Yu N.; Derbenev, Ya S.; Lin, F.; Morozov, V. S.; Zhang, Y.

2017-07-01

The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider’s lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of “interference peaks”. The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stability of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy.

Advanced low-beta cavity development for proton and ion accelerators

Energy Technology Data Exchange (ETDEWEB)

Conway, Z.A., E-mail: zconway@anl.gov; Kelly, M.P.; Ostroumov, P.N.

2015-05-01

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3 MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3 MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review this work where we have achieved surface fields greater than 166 mT magnetic and 117 MV/m electric in a 72 MHz quarter-wave resonator optimized for β = 0.077 ions.

Advanced low-beta cavity development for proton and ion accelerators

Energy Technology Data Exchange (ETDEWEB)

Conway, Z. A.; Kelly, M. P.; Ostroumov, P. N.

2015-05-01

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3 MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3 MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review this work where we have achieved surface fields greater than 166 mT magnetic and 117 MV/m electric in a 72 MHz quarter-wave resonator optimized for beta = 0.077 ions.

Advanced low-beta cavity development for proton and ion accelerators

International Nuclear Information System (INIS)

Conway, Z.A.; Kelly, M.P.; Ostroumov, P.N.

2015-01-01

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3 MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3 MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review this work where we have achieved surface fields greater than 166 mT magnetic and 117 MV/m electric in a 72 MHz quarter-wave resonator optimized for β = 0.077 ions

Efficiencies for production of atomic nitrogen and oxygen by relativistic proton impact in air

Science.gov (United States)

Porter, H. S.; Jackman, C. H.; Green, A. E. S.

1976-01-01

Relativistic electron and proton impact cross sections are obtained and represented by analytic forms which span the energy range from threshold to 1 GeV. For ionization processes, the Massey-Mohr continuum generalized oscillator strength surface is parameterized. Parameters are determined by simultaneous fitting to (1) empirical data, (2) the Bethe sum rule, and (3) doubly differential cross sections for ionization. Branching ratios for dissociation and predissociation from important states of N2 and O2 are determined. The efficiency for the production of atomic nitrogen and oxygen by protons with kinetic energy less than 1 GeV is determined using these branching ratio and cross section assignments.

Semi-classical approaches for the proton emission in intermediate energy heavy ion reactions

International Nuclear Information System (INIS)

Gregoire, C.; Scheuter, F.; Remaud, B.; Sebille, F.

1984-05-01

Semi-classical approaches are proposed to study the transition between the one- and two-body processes in intermediate energy heavy ion collisions. The Landau-Vlasov equation is used as a transport equation for nucleons in the nuclear matter. We apply our formalism to the fast proton ejection. On the one hand, the effects of the nucleon-nucleon collisions are studied for the particles which travel through the nucleus cores. On the other hand, the inertial emission turns out to be an important proton emission mechanism. Our results conflict the interpretation of the proton spectra in terms of moving sources. Reasonable agreements with the experimental data are found without reference to any thermal equilibrium

A proton-recoil neutron spectrometer for time-dependent ion temperatures on the National Ignition Facility

International Nuclear Information System (INIS)

Murphy, T.J.

1995-01-01

Ion temperatures from inertial confinement fusion targets are usually determined by measuring the Doppler broadening of the neutron spectrum using the time-of-flight method. Measurement systems are generally designed so that the contribution of the duration of neutron production (∼100 ps) to the width of the neutron signal is negligible. This precludes the possibility of time-dependent ion temperature. If, however, one could measure the neutron energy and arrival time at a detector independently, then time-dependent neutron spectra could be obtained, and ion temperature information deduced. A concept utilizing a proton-recoil neutron spectrometer has been developed in which recoil protons from a small plastic foil are measured. From the energy, arrival time, and recoil angle of the recoil proton, the birth time and energy of the incident neutron can be deduced. The sensitivity of the system is low, but the higher anticipated neutron yields from the proposed National Ignition Facility may make the technique feasible. Large scintillator arrays currently in use on the Nova facility for neutron spectral measurements consist of ∼1,000 channels and detect between 50 and 500 counts for typical time-integrated data. Time-dependent results would then require about an order of magnitude larger system. Key issues for making this system feasible will be keeping the cost per channel low while allowing adequately time (∼ 50 ps), energy (20 keV), and angular resolution (2 mrad) for each of the proton detectors

Use of Proton SEE Data as a Proxy for Bounding Heavy-Ion SEE Susceptibility

Science.gov (United States)

Ladbury, Raymond L.; Lauenstein, Jean-Marie; Hayes, Kathryn P.

2015-01-01

Although heavy-ion single-event effects (SEE) pose serious threats to semiconductor devices in space, many missions face difficulties testing such devices at heavy-ion accelerators. Low-cost missions often find such testing too costly. Even well funded missions face issues testing commercial off the shelf (COTS) due to packaging and integration. Some missions wish to fly COTS systems with little insight into their components. Heavy-ion testing such parts and systems requires access to expensive and hard-to-access ultra-high energy ion accelerators, or significant system modification. To avoid these problems, some have proposed using recoil ions from high-energy protons as a proxy to bound heavy-ion SEE rates.

Damage induced by high energy multiply charged oxygen ions in oxide coated silicon

Energy Technology Data Exchange (ETDEWEB)

Dhole, S.D. [Department of Physics, University of Pune, Pune 411 007 (India)]. E-mail: sanjay@physics.unipune.ernet.in; Dahiwale, S.S. [Department of Physics, University of Pune, Pune 411 007 (India); Kulkarni, V.R. [Department of Physics, University of Pune, Pune 411 007 (India); Bogle, K.A. [Department of Physics, University of Pune, Pune 411 007 (India); Shinde, N.S. [Ecotopia Science Institute, Division of Energy Science, Nagoya University, Nagoya (Japan); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411 007 (India)

2006-03-15

P-type oxide coated silicon samples of resistivity 120 {omega} cm were irradiated with 60 MeV oxygen ions of fixed charge states 4{sup +}, 5{sup +}, 6{sup +} and 7{sup +} at an equal fluence of, {phi}, {approx}10{sup 13} ions/cm{sup 2}. The induced damage was estimated by Hall voltage, Hall coefficient, carrier concentration and lifetime of minority carriers. The results indicate that Hall voltage (V {sub H}) and Hall coefficient (R {sub H}) increases, while carrier concentration (n) decreases with the charge state of impinging oxygen ions. The V {sub H} increases from 22 mV to 76.5 mV at typical current of 0.5 mA, R {sub H} from 0.42 x 10{sup 5} cm{sup 3}/C to 2.16 x 10{sup 5} cm{sup 3}/C and n decreases from 9 x 10{sup 13} cm{sup -3} to 2.88 x 10{sup 13} cm{sup -3} for the different charge states. This fact is an evidence that the oxygen ions with an individual fixed charge state passing through very thin 40 A layer of silicon dioxide, induces significant damage at the SiO{sub 2}-Si interface through the mechanism of electronic stopping power. The lifetime of minority charge carriers, {tau} (bulk property), remains constant at around 6 {mu}s for all the charge states of the 60 MeV energy oxygen ion irradiated samples at a constant fluence of, {phi}, 10{sup 13} ions/cm{sup 2}.

SU-E-T-755: Timing Characteristics of Proton and Carbon Ion Treatments Using a Synchrotron and Modulated Scanning

International Nuclear Information System (INIS)

Zhao, J; Li, Y; Huang, Z; Deng, Y; Sun, L; Moyers, M; Hsi, W; Wu, X

2015-01-01

Purpose: The time required to deliver a treatment impacts not only the number of patients that can be treated each day but also the accuracy of delivery due to potential movements of patient tissues. Both macroscopic and microscopic timing characteristics of a beam delivery system were studied to examine their impacts on patient treatments. Methods: 35 patients were treated during a clinical trial to demonstrate safety and efficacy of a Siemens Iontris system prior to receiving approval from the Chinese Food and Drug Administration. The system has a variable cycle time and can provide proton beams from 48 to 221 MeV/n and carbon ions from 86 to 430 MeV/n. A modulated scanning beam delivery technique is used where the beam remains stationary at each spot aiming location and is not turned off while the spot quickly moves from one aiming location to the next. The treatment log files for 28 of the trial patients were analyzed to determine several timing characteristics. Results: The average portal time per target dose was 172.5 s/Gy for protons and 150.7 s/Gy for carbon ions. The maximum delivery time for any portal was less than 300 s. The average dwell time per spot was 12 ms for protons and 3.0 ms for carbon ions. The number of aiming positions per energy layer varied from 1 to 258 for protons and 1 to 621 for carbon ions. The average spill time and cycle time per energy layer were 1.20 and 2.68 s for protons and 0.95 and 4.73 s for carbon ions respectively. For 3 of the patients, the beam was gated on and off to reduce the effects of respiration. Conclusion: For a typical target volume of 153 cc as used in this clinical trial, the portal delivery times were acceptable

Reduction by metals dissolved in liquid ammonia of keto steroids. Equilibration of the alcohols

International Nuclear Information System (INIS)

Giroud, A.M.

1970-01-01

Reducing a ketone by dissolved metals involves two electrons; we may consider as intermediate a radical-anion, then a di-anion or a carbo-anion. The radical-anion may also split and give pinacols away. In order to discuss the reduction proceeds, we had to know the respective stabilities of the alcohols, which lead us to effectuate equilibration. The first chapter is devoted to the method of preparing the androstanone-II and the androstanols-IIα and II-β. We further establish the impossibility of using our methods for reaching a conclusion about the alcohols relative stability by experimental equilibration. Last we describe the methods for reducing the ketone by alkaline and earth-alkaline metals, dissolved in liquid ammonia, either in contact with a protons donor or with a later added protons donor. The resulting mixture of the two alcohols shows a prevailing quantity of the stable equatorial isomer α. In a second chapter, we study the action of selenic acid and hydroperoxide on cholestanone-3, which leads us to study the preparation and stereochemistry of the A-nor cholestane derivates. We further describe the preparation of the A-nor cholestanols-2α and 2β, and the corresponding acetates. Equilibration of the alcohols by chemical methods shows the 2 α-alcohol more stable than the 2β, which is mathematically confirmed. Last, the reduction of the A-nor cholestanone-2 by dissolved metals consistently leads to the less stable 2 β epimer, with associated pinacols. The third chapter is devoted to the study of the androstanone-17 reductions, and the relative stabilities of the 17α and 17β alcohols. Whichever operating methods is used, we predominantly obtain the more stable 17β alcohol. In all cases, a pinacol production is observed. Summing up, we note that, in all cases, we predominantly obtain the equatorial epimer, whether it should be the more stable or the less stable. (author) [fr

Hydrogen ion (Ph), ammonia, dissolved oxygen and nitrite ...

African Journals Online (AJOL)

Hydrogen ion (pH), dissolved oxygen, ammonia and nitrite concentrations were studied monthly in two systems (re-circulatory and semi-intensive of 3 m2 sizes) each for six months. The systems were each stocked with 200 g of Clarias gariepinus fingerlings. Results showed that all parameters were within acceptable limits ...

Measurement of L X-ray intensity ratios in tantalum by proton and Si-ion impact

International Nuclear Information System (INIS)

Braich, J.S.; Dhal, B.B.; Singh, B.P.; Padhi, H.C.; Khurana, C.S.; Verma, H.R.

1996-01-01

The Lι, Lβ 1,4,6 , Lβ 2,15,3 , Lγ 1 , Lγ 2,3,6 and Lγ 4,4' , X-ray intensities relative to the Lα, caused by the impact of protons of energy 1 to 4.6 MeV and Si-ions of 70 to 98 MeV on Ta targets, h ave been measured. The results show that the intensity ratios drop significantly for all transitions except Lγ 2,3,6 /Lα with Si-ions of the same energy/amu as compared to those of protons. The experimental results have been compared with those based on the ECPSSR theoretical values. From the energy shift and change in the intensity ratios of various transitions caused by Si-ion impact, the number of outer shell vacancies in the M, N and O-shells simultaneous to that of L-shell have been estimat ed. (orig.)

Unusual features of proton and α-spectra from low-energy heavy-ion ...

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 75; Issue 1. Unusual features ... Keywords. Proton and α-spectra; heavy-ion reaction; broad structures; nuclear level density. ... The broad structures in the -spectra cannot be fully explained within the statistical model even with the enhanced level density. In this case ...

Oxygen ion transference number of doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Meilin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

2008-12-01

The transference numbers for oxygen ion (t{sub O}) in several LaGaO{sub 3}-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications. (author)

Proton and hydrogen formation by cyclohexyl benzene during overcharge of Li-ion batteries

Science.gov (United States)

Lee, Hochun; Kim, Soojin; Jeon, Jongho; Cho, Jeong-Ju

This study provides experimental evidence for proton and hydrogen formation caused by the anodic electropolymerization of cyclohexyl benzene (CHB), which is a popular electrolyte additive for overcharge protection of lithium-ion batteries (LIBs). It is found that considerable H 2 evolution is observed in overcharged LiCoO 2/graphite cells, especially when CHB is included as an electrolyte additive. In order to confirm the proton generation during the CHB oxidation, Pt/Pt-rotating ring disc electrode (RRDE) measurements are performed in 1 M Li(C 2F 5SO 2) 2N ethylene carbonate/ethyl methyl carbonate (1/2, v/v) solutions with and without CHB. The cathodic ring current is intimately correlated to the anodic disc current, and the cathodic reaction at the ring is determined to be the reduction of the proton. The proton generation efficiency during the CHB oxidation is as high as 90%. Proton liberation is also observed during the anodic decomposition of the electrolyte solvents, although it occurs in a much less stoichiometric way compared with that during the CHB oxidation.

Emission characteristics of negative oxygen ions into vacuum from cerium oxide

International Nuclear Information System (INIS)

Sakai, Takaaki; Fujiwara, Yukio; Kaimai, Atsushi; Yashiro, Keiji; Matsumoto, Hiroshige; Nigara, Yutaka; Kawada, Tatsuya; Mizusaki, Junichiro

2006-01-01

The oxygen ion emission characteristics of CeO 2 were studied under electric field in a vacuum chamber to find a candidate material for a novel ion source, 'solid oxide ion source (SOIS)'. The emission current was observed from CeO 2 under a pressure of around 10 -3 Pa, at the temperature ranging from 973 K to 1173 K. It was found that the emission current increased with temperature and applied voltage. The ions emitted from CeO 2 were confirmed to be oxygen negative ions (O - ) by the use of quadrupole mass spectrometer. The emission current decreased with time as was observed in the earlier works with other oxide ion conductors such as stabilized zirconia or other materials . To enhance the emission current from CeO 2 , an introduction of donor into CeO 2 was tested using Ce 0.992 Nb 0.008 O 2 . For comparison, effect of acceptor doping was also tested using Ce 0.9 Gd 0.1 O 1.95 . The emission current from Ce 0.9 Gd 0.1 O 1.95 was smaller than that from donor-doped and pure CeO 2. Clear enhancement of the emission current was not observed with Ce 0.992 Nb 0.008 O 2

Strangeness chemical equilibration in a quark-gluon plasma

International Nuclear Information System (INIS)

Letessier, Jean; Rafelski, Johann

2007-01-01

We study, in the dynamically evolving quark-gluon plasma (QGP) fireball formed in relativistic heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC), the growth of strangeness yield toward and beyond the chemical equilibrium. We account for the contribution of the direct strangeness production and evaluate the thermal-QCD strangeness production mechanisms. The specific yield of strangeness per entropy, s/S, is the primary target variable. We explore the effect of collision impact parameter, i.e., fireball size, on kinetic strangeness chemical equilibration in QGP. Insights gained in studying the RHIC data with regard to the dynamics of the fireball are applied to the study of strangeness production at the LHC. We use these results and consider the strange hadron relative particle yields at RHIC and LHC in a systematic fashion. We consider both the dependence on s/S and the direct dependence on the participant number

Systematic analysis of neutron yields from thick targets bombarded by heavy ions and protons with moving source model

Energy Technology Data Exchange (ETDEWEB)

Kato, Takashi; Kurosawa, Tadahiro; Nakamura, Takashi E-mail: nakamura@cyric.tohoku.ac.jp

2002-03-21

A simple phenomenological analysis using the moving source model has been performed on the neutron energy spectra produced by bombarding thick targets with high energy heavy ions which have been systematically measured at the Heavy-Ion Medical Accelerator (HIMAC) facility (located in Chiba, Japan) of the National Institute of Radiological Sciences (NIRS). For the bombardment of both heavy ions and protons in the energy region of 100-500 MeV per nucleon, the moving source model incorporating the knock-on process could be generally successful in reproducing the measured neutron spectra within a factor of two margin of accuracy. This phenomenological analytical equation is expressed having several parameters as functions of atomic number Z{sub p}, mass number A{sub p}, energy per nucleon E{sub p} for projectile, and atomic number Z{sub T}, mass number A{sub T} for target. By inputting these basic data for projectile and target into this equation we can easily estimate the secondary neutron energy spectra at an emission angle of 0-90 deg. for bombardment with heavy ions and protons in the aforementioned energy region. This method will be quite useful to estimate the neutron source term in the neutron shielding design of high energy proton and heavy ion accelerators.

Proton-oxygen conductivity in substituted perovskites ATi0.95Mo0.05O3-α (A = Ca, Sr, Ba; M = Sc, Mg) in the reducing hydrogen-containing atmospheres

International Nuclear Information System (INIS)

Gorelov, V.P.; Balakireva, V.B.; Sharova, N.V.

1999-01-01

Electric conductivity depending on temperature, oxygen partial pressure, as well as the number of t i ion transfer and transfer hydrogen numbers in the perovskites ATi 0.95 Mo 0.05 O 3-α (A = Ca, Sr, Ba; M = Sc, Mg) in reducing hydrogen-containing atmospheres in the temperature range of 450-850 deg C have been measured. With the temperature decrease t i increases reaching 1.0 at a temperature of 550 deg C for all compositions. Proton conductivity under conditions of assumed concomitant transfer of either O 2- or OH - has been ascertained [ru

Minibeam Therapy With Protons and Light Ions: Physical Feasibility and Potential to Reduce Radiation Side Effects and to Facilitate Hypofractionation

Energy Technology Data Exchange (ETDEWEB)

Dilmanian, F. Avraham, E-mail: avraham.dilmanian@stonybrook.edu [Departments of Radiation Oncology, Neurology, and Radiology, Stony Brook University Medical Center, Stony Brook, New York (United States); Eley, John G. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Krishnan, Sunil [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2015-06-01

Purpose: Despite several advantages of proton therapy over megavoltage x-ray therapy, its lack of proximal tissue sparing is a concern. The method presented here adds proximal tissue sparing to protons and light ions by turning their uniform incident beams into arrays of parallel, small, or thin (0.3-mm) pencil or planar minibeams, which are known to spare tissues. As these minibeams penetrate the tissues, they gradually broaden and merge with each other to produce a solid beam. Methods and Materials: Broadening of 0.3-mm-diameter, 109-MeV proton pencil minibeams was measured using a stack of radiochromic films with plastic spacers. Monte Carlo simulations were used to evaluate the broadening in water of minibeams of protons and several light ions and the dose from neutron generated by collimator. Results: A central parameter was tissue depth, where the beam full width at half maximum (FWHM) reached 0.7 mm, beyond which tissue sparing decreases. This depth was 22 mm for 109-MeV protons in a film stack. It was also found by simulations in water to be 23.5 mm for 109 MeV proton pencil minibeams and 26 mm for 116 MeV proton planar minibeams. For light ions, all with 10 cm range in water, that depth increased with particle size; specifically it was 51 mm for Li-7 ions. The ∼2.7% photon equivalent neutron skin dose from the collimator was reduced 7-fold by introducing a gap between the collimator and the skin. Conclusions: Proton minibeams can be implemented at existing particle therapy centers. Because they spare the shallow tissues, they could augment the efficacy of proton therapy and light particle therapy, particularly in treating tumors that benefit from sparing of proximal tissues such as pediatric brain tumors. They should also allow hypofractionated treatment of all tumors by allowing the use of higher incident doses with less concern about proximal tissue damage.

Flavour equilibration studies of quark-gluon plasma with non-zero ...

Indian Academy of Sciences (India)

Abstract. Flavour equilibration for a thermally equilibrated but chemically non- equilibrated quark-gluon plasma is presented. Flavour equilibration is studied enforcing baryon number conservation. In addition to the usual processes like single additional gluon production gg ⇌ ggg and its reverse and quark–antiquark pair ...

SU-E-T-146: Reference Dosimetry for Protons and Light-Ion Beams Based on Graphite Calorimetry.

Science.gov (United States)

Rossomme, S; Palmans, H; Thomas, R; Lee, N; Bailey, M; Shipley, D; Al-Sulaiti, L; Cirrone, P; Romano, F; Kacperek, A; Bertrand, D; Vynckier, S

2012-06-01

The IAEA TRS-398 code of practice can be applied for the measurement of absorbed dose to water under reference conditions with an ionization chamber. For protons, the combined relative standard uncertainty on those measurements is less than 2% while for light-ion beams, it is considerably larger, i.e. 3.2%, mainly due to the higher uncertainty contributions for the water to air stopping power ration and the W air-value on the beam quality correction factors kQ,Q 0 . To decrease this uncertainty, a quantification of kQ,Q 0 is proposed using a primary standard level graphite calorimeter. This work includes numerical and experimental determinations of dose conversion factors to derive dose to water from graphite calorimetry. It also reports on the first experimental data obtained with the graphite calorimeter in proton, alpha and carbon ion beams. Firstly, the dose conversion has been calculated with by Geant4 Monte-Carlo simulations through the determination of the water to graphite stopping power ratio and the fluence correction factor. The latter factor was also derived by comparison of measured ionization curves in graphite and water. Secondly, kQ,Q 0 was obtained by comparison of the dose response of ionization chambers with that of the calorimeter. Stopping power ratios are found to vary by no more than 0.35% up to the Bragg peak, while fluence correction factors are shown to increase slightly above unity close to the Bragg peak. The comparison of the calorimeter with ionization chambers is currently under analysis. For the modulated proton beam, preliminary results on W air confirm the value recommended in TRS-398. Data in both the non-modulated proton and light-ion beams indicate higher values but further investigation of heat loss corrections is needed. The application of graphite calorimetry to proton, alpha and carbon ion beams has been demonstrated successfully. Other experimental campaigns will be held in 2012. This work is supported by the BioWin program

Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

KAUST Repository

Alquaity, Awad B. S.

2017-01-01

Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

Charged particle production in proton-, deuteron-, oxygen- and sulphur-nucleus collisions at 200 GeV per nucleon

CERN Document Server

Alber, T.; Bachler, J.; Bartke, J.; Bialkowska, H.; Bloomer, M.A.; Bock, R.; Braithwaite, W.J.; Brinkmann, D.; Brockmann, R.; Buncic, P.; Chan, P.; Cramer, J.G.; Cramer, P.B.; Derado, I.; Eckardt, V.; Eschke, J.; Favuzzi, C.; Ferenc, D.; Fleischmann, B.; Foka, P.; Freund, P.; Fuchs, M.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Gunther, J.; Harris, J.W.; Hoffmann, M.; Jacobs, P.; Kabana, S.; Kadija, K.; Keidel, R.; Kowalski, M.; Kuhmichel, A.; Lee, J.Y.; Ljubicic, A, Jr.; Margetis, S.; Mitchell, J.T.; Morse, R.; Nappi, E.; Odyniec, G.; Paic, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Posa, F.; Poskanzer, Arthur M.; Puhlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Rohrich, D.; Roland, G.; Rothard, H.; Runge, K.; Sandoval, A.; Schmitz, N.; Schmoetten, E.; Sendelbach, R.; Seyboth, P.; Seyerlein, J.; Skrzypczak, E.; Spinelli, P.; Stock, R.; Strobele, H.; Teitelbaum, L.; Tonse, S.; Trainor, T.A.; Vasileiadis, G.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Wenig, S.; Wosiek, B.; Zhu, X.

1998-01-01

The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton-nucleus and deuteron-gold interactions, as well as central oxygen-gold and sulphur-nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus-nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with `temperatures' between 145 +- 11 MeV (p+S interactions) and 244 +- 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse mom...

Strangeness Production in a Chemically Equilibrating Quark-Gluon Plasma

Institute of Scientific and Technical Information of China (English)

HE Ze-Jun; LONG Jia-Li; MA Yu-Gang; MA Guo-Liang

2004-01-01

@@ We study the strangeness of a chemically equilibrating quark-gluon plasma at finite baryon density based on the and will accelerate with the change of the initial system from a chemically non-equilibrated to an equilibrated system. We also find that the calculated strangeness is very different from the one in the thermodynamic equilibrium system. This study may be helpful to understand the formation of quark-gluon plasma via a chemically non-equilibrated evolution framework.

A coincidence-type ion-electron converter detector for low-energy protons

International Nuclear Information System (INIS)

Benka, O.; Weinzierl, P.; Dobrozemsky, R.; Stratowa, C.

1981-04-01

A coincidence type ion-electron converter detector has been developed and used - together with an electrostatic energy-analyser - for precision measurements of the energy distribution of recoil protons from free-neutron decay. The most important aspect of the development was, besides keeping the background below 0,2 counts/sec in the presence of a certain radiation background, to achieve a high and energy-independent counting probability for protons with energies between 100 and 1000 eV. With an acceleration voltage of about 25 kV and Al-foils (20 to 35 ug/cmsup2) as converter, we obtained counting efficiences of 70 to 85 percent. The design and performance of the detector system, employing six foils with different sensitive areas, are described and discussed in detail. (author)

Equilibration and thermalization in finite quantum systems

International Nuclear Information System (INIS)

Yukalov, V I

2011-01-01

Experiments with trapped atomic gases have opened novel possibilities for studying the evolution of nonequilibrium finite quantum systems, which revived the necessity of reconsidering and developing the theory of such processes. This review analyzes the basic approaches to describing the phenomena of equilibration, thermalization, and decoherence in finite quantum systems. Isolated, nonisolated, and quasi-isolated quantum systems are considered. The relations between equilibration, decoherence, and the existence of time arrow are emphasized. The possibility for the occurrence of rare events, preventing complete equilibration, are mentioned

Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2.

Science.gov (United States)

Maitra, Urmimala; House, Robert A; Somerville, James W; Tapia-Ruiz, Nuria; Lozano, Juan G; Guerrini, Niccoló; Hao, Rong; Luo, Kun; Jin, Liyu; Pérez-Osorio, Miguel A; Massel, Felix; Pickup, David M; Ramos, Silvia; Lu, Xingye; McNally, Daniel E; Chadwick, Alan V; Giustino, Feliciano; Schmitt, Thorsten; Duda, Laurent C; Roberts, Matthew R; Bruce, Peter G

2018-03-01

The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li + -O(2p)-Li + interactions). Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg 2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg 2+ remains in Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 , which stabilizes oxygen.

Ion release from magnesium materials in physiological solutions under different oxygen tensions.

Science.gov (United States)

Feyerabend, Frank; Drücker, Heiko; Laipple, Daniel; Vogt, Carla; Stekker, Michael; Hort, Norbert; Willumeit, Regine

2012-01-01

Although magnesium as degradable biomaterial already showed clinical proof of concepts, the design of new alloys requires predictive in vitro methods, which are still lacking. Incubation under cell culture conditions to obtain "physiological" corrosion may be a solution. The aim of this study was to analyse the influence of different solutions, addition of proteins and of oxygen availability on the corrosion of different magnesium materials (pure Mg, WE43, and E11) with different surface finishing. Oxygen content in solution, pH, osmolality and ion release were determined. Corrosion led to a reduction of oxygen in solution. The influence of oxygen on pH was enhanced by proteins, while osmolality was not influenced. Magnesium ion release was solution-dependent and enhanced in the initial phase by proteins with delayed release of alloying elements. The main corrosion product formed was magnesium carbonate. Therefore, cell culture conditions are proposed as first step toward physiological corrosion.

Equilibrator: Modeling Chemical Equilibria with Excel

Science.gov (United States)

Vander Griend, Douglas A.

2011-01-01

Equilibrator is a Microsoft Excel program for learning about chemical equilibria through modeling, similar in function to EQS4WIN, which is no longer supported and does not work well with newer Windows operating systems. Similar to EQS4WIN, Equilibrator allows the user to define a system with temperature, initial moles, and then either total…

Study of heavy flavours from muons measured with the ALICE detector in proton-proton and heavy-ion collisions at the CERN-LHC

International Nuclear Information System (INIS)

Zhang, X.

2012-01-01

ALICE (A Large Ion Collider Experiment) is the experiment dedicated to the study of heavy-ion collisions at the LHC. ALICE also takes part in the LHC proton- proton program which is of great interest for testing perturbative QCD calculations at unprecedented low Bjorken-x values and for providing the necessary baseline for nucleus-nucleus and proton-nucleus collisions. ALICE will also collect, in the beginning of 2013, p-Pb/Pb-p collisions in order to investigate cold nuclear matter effects. ALICE measures quarkonia and open heavy flavours with (di)-electrons, (di)-muons and through the hadronic channels. This thesis work is devoted to the study of open heavy flavours in proton-proton and Pb-Pb collisions via single muons with the ALICE forward muon spectrometer. The document is organized as follows. The first chapter consists in a general introduction on heavy-ion collisions and QCD phase transitions. Chapter 2 summarizes the motivations for the study of open heavy flavours in nucleon-nucleon, nucleon-nucleus and nucleus-nucleus collisions. Chapter 3 gives an overview of the ALICE experiment with a detailed description of the forward muon spectrometer. Chapter 4 gives a short summary of the ALICE online and offline systems. Then the analysis framework (for data and simulations) and in particular the software developed for the study of open heavy flavours is detailed. Chapter 5 summarizes the performance of the ALICE muon spectrometer for the study of the production of open heavy flavours in pp collisions via single muons and dimuons. Chapters 6 to 9 are dedicated to data analysis. Chapter 6 deals with the analysis of first pp collisions at 900 GeV. The main aim was the understanding of the response of the apparatus. Chapter 7 presents the measurement of the production of heavy flavour decay muons in pp collisions at √(s) = 7 TeV. The analysis strategy is described: event and track selection, background subtraction (mainly the contribution of muons from primary

Equilibration in the time-dependent Hartree-Fock approach probed with the Wigner distribution function

International Nuclear Information System (INIS)

Loebl, N.; Maruhn, J. A.; Reinhard, P.-G.

2011-01-01

By calculating the Wigner distribution function in the reaction plane, we are able to probe the phase-space behavior in the time-dependent Hartree-Fock scheme during a heavy-ion collision in a consistent framework. Various expectation values of operators are calculated by evaluating the corresponding integrals over the Wigner function. In this approach, it is straightforward to define and analyze quantities even locally. We compare the Wigner distribution function with the smoothed Husimi distribution function. Different reaction scenarios are presented by analyzing central and noncentral 16 O + 16 O and 96 Zr + 132 Sn collisions. Although we observe strong dissipation in the time evolution of global observables, there is no evidence for complete equilibration in the local analysis of the Wigner function. Because the initial phase-space volumes of the fragments barely merge and mean values of the observables are conserved in fusion reactions over thousands of fm/c, we conclude that the time-dependent Hartree-Fock method provides a good description of the early stage of a heavy-ion collision but does not provide a mechanism to change the phase-space structure in a dramatic way necessary to obtain complete equilibration.

TU-G-BRB-05: Panel Discussion: Clinical Trials in Proton and Ion Therapy - Are We Ready?

International Nuclear Information System (INIS)

Schulte, R.

2015-01-01

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. The lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial

New insights into methane-oxygen ion chemistry

KAUST Repository

Alquaity, Awad B.S.; Chen, Bingjie; Han, Jie; Selim, Hatem; Belhi, Memdouh; Karakaya, Yasin; Kasper, Tina; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

2016-01-01

External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

New insights into methane-oxygen ion chemistry

KAUST Repository

Alquaity, Awad B.S.

2016-06-15

External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

Voyager observations of O(+6) and other minor ions in the solar wind

Science.gov (United States)

Villanueva, Louis; Mcnutt, Ralph L., Jr.; Lazarus, Alan J.; Steinberg, John T.

1994-01-01

The plasma science (PLS) experiments on the Voyager 1 and 2 spacecraft began making measurements of the solar wind shortly after the two launches in the fall of 1977. In reviewing the data obtained prior to the Jupiter encounters in 1979, we have found that the large dynamic range of the PLS instrument generally allows a clean separation of signatures of minor ions (about 2.5% of the time) during a single instrument scan in energy per charge. The minor ions, most notably O(+6), are well separated from the protons and alpha particles during times when the solar wind Mach number (ratio of streaming speed to thermal speed) is greater than approximately 15. During the Earth to Jupiter cruise we find that the average ratio of alpha particle number density to that of oxygen is 66 +/- 7 (Voyager 1) and 71 +/- 17 (Voyager 2). These values are consistent with the value 75 +/- 20 inferred from the Ion Composition Instrument on ISEE 3 during the period spanning 1978 and 1982. We have inferred an average coronal temperature of (1.7 +/- 0.1) x 10(exp 6) K based on the ratio of O(+7) to O(+6) number densities. Our observations cover a period of increasing solar activity. During this time we have found that the alpha particle to proton number density ratio is increasing with the solar cycle, the oxygen to proton ratio increases, and the alpha particle to oxygen ratio remains relatively constant in time.

Long-term operation experience with 2 ECR ion sources and planned extensions at HIT

International Nuclear Information System (INIS)

Winkelmann, T.; Cee, R.; Haberer, T.; Naas, B.; Peters, A.

2012-01-01

The HIT (Heidelberg Ion Beam Therapy Center) is the first treatment facility at a hospital in Europe where patients can be treated with protons and carbon ions. Since the commissioning starting in 2006 two 14.5 GHz electron cyclotron resonance ion sources are routinely used to produce a variety of ion beams from protons up to oxygen. The operating time is 330 days per year, our experience after three years of continuous operation will be presented. In the future a helium beam for patient treatment is requested, therefore a third ion source will be integrated. This third ECR source with a newly designed extraction system and a spectrometer line will be installed at a test-bench to commission and validate this section. Different test settings are foreseen to study helium operation as well as enhanced parameter sets for proton and carbon beams in combination with a modified beam transport line for higher transmission efficiency. An outlook to the possible integration scheme of the new ion source into the production facility will be discussed. The paper is followed by the associated poster. (authors)

Effect of long-term equilibration on the toxicity of molybdenum to soil organisms

International Nuclear Information System (INIS)

Gestel, Cornelis A.M. van; McGrath, Steve P.; Smolders, Erik; Diez Ortiz, Maria; Borgman, Eef; Verweij, Rudo A.; Buekers, Jurgen; Oorts, Koen

2012-01-01

To determine if long-term equilibration may alleviate molybdenum toxicity, earthworms, enchytraeids, collembolans and four plant species were exposed to three soils freshly spiked with Na 2 MoO 4 .2H 2 O and equilibrated for 6 or 11 months in the field with free drainage. Total Mo concentrations in soil decreased by leaching, most (up to 98%) in sandy soil and less (54–62%) in silty and clayey soils. Changes in residual Mo toxicity with time were inconclusive in sandy soil. In the other two soils, toxicity of residual total Mo was significantly reduced after 11 months equilibration with a median 5.5-fold increase in ED50s. Mo fixation in soil, i.e. the decrease of soil solution Mo concentrations at equivalent residual total soil Mo, was maximally a factor of 2.1 only. This experiment shows natural attenuation of molybdate ecotoxicity under field conditions is related to leaching of excess Mo and other ions as well as to slow ageing reactions. - Highlights: ► Three molybdate-spiked soils were equilibrated for 6 and 11 months outdoors. ► Mo chronic toxicity to earthworms, enchytraeids, Collembola and four plant species was assessed. ► Mo concentrations in all soils decreased due to leaching. ► Based on actual total Mo remaining in the soil, Mo toxicity decreased by a median factor of 5.5. ► Decreased Mo toxicity was due to leaching as well as slow ageing reactions. - Natural attenuation under field conditions is more related to leaching of excess molybdate than to slow ageing reactions

Transport of oxygen ions in Er doped La2Mo2O9 oxide ion conductors: Correlation with microscopic length scales

Science.gov (United States)

Paul, T.; Ghosh, A.

2018-01-01

We report oxygen ion transport in La2-xErxMo2O9 (0.05 ≤ x ≤ 0.25) oxide ion conductors. We have measured conductivity and dielectric spectra at different temperatures in a wide frequency range. The mean square displacement and spatial extent of non-random sub-diffusive regions are estimated from the conductivity spectra and dielectric spectra, respectively, using linear response theory. The composition dependence of the conductivity is observed to be similar to that of the spatial extent of non-random sub-diffusive regions. The behavior of the composition dependence of the mean square displacement of oxygen ions is opposite to that of the conductivity. The attempt frequency estimated from the analysis of the electric modulus agrees well with that obtained from the Raman spectra analysis. The full Rietveld refinement of X-ray diffraction data of the samples is performed to estimate the distance between different oxygen lattice sites. The results obtained from such analysis confirm the ion hopping within the spatial extent of non-random sub-diffusive regions.

Double perovskite cathodes for proton-conducting ceramic fuel cells: are they triple mixed ionic electronic conductors?

Science.gov (United States)

Téllez Lozano, Helena; Druce, John; Cooper, Samuel J.; Kilner, John A.

2017-12-01

18O and 2H diffusion has been investigated at a temperature of 300 °C in the double perovskite material PrBaCo2O5+δ (PBCO) in flowing air containing 200 mbar of 2H216O. Secondary ion mass spectrometry (SIMS) depth profiling of exchanged ceramics has shown PBCO still retains significant oxygen diffusivity ( 1.3 × 10-11 cm2s-1) at this temperature and that the presence of water (2H216O), gives rise to an enhancement of the surface exchange rate over that in pure oxygen by a factor of 3. The 2H distribution, as inferred from the 2H216O- SIMS signal, shows an apparent depth profile which could be interpreted as 2H diffusion. However, examination of the 3-D distribution of the signal shows it to be nonhomogeneous and probably related to the presence of hydrated layers in the interior walls of pores and is not due to proton diffusion. This suggests that PBCO acts mainly as an oxygen ion mixed conductor when used in PCFC devices, although the presence of a small amount of protonic conductivity cannot be discounted in these materials.

Nanocrystalline SnO2 formation by oxygen ion implantation in tin thin films

Science.gov (United States)

Kondkar, Vidya; Rukade, Deepti; Kanjilal, Dinakar; Bhattacharyya, Varsha

2018-03-01

Metallic tin thin films of thickness 100 nm are deposited on fused silica substrates by thermal evaporation technique. These films are implanted with 45 keV oxygen ions at fluences ranging from 5 × 1015 to 5 × 1016 ions cm-2. The energy of the oxygen ions is calculated using SRIM in order to form embedded phases at the film-substrate interface. Post-implantation, films are annealed using a tube furnace for nanocrystalline tin oxide formation. These films are characterized using x-ray diffraction, Raman spectroscopy, UV-vis spectroscopy and photoluminescence spectroscopy. XRD and Raman spectroscopy studies reveal the formation of single rutile phase of SnO2. The size of the nanocrystallites formed decreases with an increase in the ion fluence. The nanocrystalline SnO2 formation is also confirmed by UV-vis and photoluminescence spectroscopy.

Baseline measures for net-proton distributions in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Netrakanti, P.K.; Mishra, D.K.; Mohanty, A.K.; Mohanty, B.

2014-01-01

The STAR experiment at the Relativistic Heavy-Ion Collider facility has reported results for the cumulants and their ratios from the net-proton distributions upto the fourth order cumulants at various collision energies. These measurements were carried to look for the signatures of the possible critical point (CP) in the phase diagram for a system undertaking strong interactions. The results show an intriguing dependence of the cumulant ratios C 3 /C 2 and C 4 /C 2 as a function of beam energy. The beam energy dependence appears to be non-monotonic in nature. However the experiment also reports that the energy dependence is observed to be consistent with expectation from an approach based on the independent production of proton and anti-protons in the collisions. In this paper we emphasize the need to have a proper baseline for appropriate interpretation of the cumulant measurements and argue that the comparison to independent production approach needs to be done with extreme caution

Development of the integrated control system for the microwave ion source of the PEFP 100-MeV proton accelerator

Science.gov (United States)

Song, Young-Gi; Seol, Kyung-Tae; Jang, Ji-Ho; Kwon, Hyeok-Jung; Cho, Yong-Sub

2012-07-01

The Proton Engineering Frontier Project (PEFP) 20-MeV proton linear accelerator is currently operating at the Korea Atomic Energy Research Institute (KAERI). The ion source of the 100-MeV proton linac needs at least a 100-hour operation time. To meet the goal, we have developed a microwave ion source that uses no filament. For the ion source, a remote control system has been developed by using experimental physics and the industrial control system (EPICS) software framework. The control system consists of a versa module europa (VME) and EPICS-based embedded applications running on a VxWorks real-time operating system. The main purpose of the control system is to control and monitor the operational variables of the components remotely and to protect operators from radiation exposure and the components from critical problems during beam extraction. We successfully performed the operation test of the control system to confirm the degree of safety during the hardware performance.

Development and testing of the proton exchange membrane fuel cell (PEMFC) for stationary generation; Desenvolvimento e ensaios de uma celula a combustivel de polimero solido (PEMFC) para geracao estacionaria

Energy Technology Data Exchange (ETDEWEB)

Ellern, Mara; Boccuzzi, Cyro Vicente [ELETROPAULO, Sao Caetano, SP (Brazil)], e-mail: mara.ellern@aes.com; Ett, Gerhard; Saiki, Gerson Yukio; Janolio, Gilberto [ELECTROCELL, Sao Paulo, SP (Brazil); Jardini, Jose Antonio [Universidade de Sao Paulo (USP), SP (Brazil)

2004-07-01

PEM (Proton Exchange Membrane) fuel cell uses a simple chemical reaction to combine hydrogen and oxygen into water, producing electric current in the process. It works something like reversed electrolysis: at the anode, hydrogen molecules give up electrons, forming hydrogen ions (this process is made possible by the platinum catalyst). The proton exchange membrane allows protons to flow through, but not electrons. As a result, the hydrogen ions flow directly through the proton exchange membrane to the cathode, while the electrons flow through an external circuit. As they travel to the cathode through the external circuit, the electrons produce electrical current. At the cathode, the electrons and hydrogen ions combine with oxygen to form water. In a fuel cell, hydrogen's natural tendency to oxidize and form water produces electricity and useful work. No pollution is produced and the only byproducts are water and heat. The huge advance on materials development combined with the growth demand of lower impact on environment is placing the fuel cells on the top of the most promising technologies world-wide. They are becoming in medium term feasible alternatives for energy generators up to energy plants of few MW. (author)

Fragment formation in light-ion induced reactions

International Nuclear Information System (INIS)

Hirata, Yuichi

2001-01-01

The intermediate mass fragment (IMF) formation in the 12 GeV proton induced reaction on Au target is analyzed by the quantum molecular dynamics model combined with the JAM hadronic cascade model and the non-equilibrated percolation model. We show that the sideward peaked angular distribution of IMF occur in the multifragmentation at very short time scale around 20 fm/c where non-equilibrated features of the residual nucleus fluctuates the nucleon density and fragments in the repulsive Coulomb force are pushed for the sideward direction. (author)

Codes of practice and protocols for the dosimetry in reference conditions of proton and ion beams

International Nuclear Information System (INIS)

Vatnitsky, S.; Andreo, P.

2002-01-01

The advantages of radiotherapy protons and heavier charged-particle beams, the technological feasibility, and the clinical results obtained so far have led to the establishment of about 20 treatment facilities worldwide and plans to open another 20 proton and light-ion therapy centres in the next five years. In order to meet the expanding capabilities of treatment techniques, considerable effort has been devoted during the last fifteen years to the development of the dosimetry and calibration of such beams. This paper reviews these developments and summarizes the present status of Codes of Practice and protocols for the dosimetry in reference conditions of proton and ion beams. The first dosimetry protocol for heavy-particle radiotherapy beams, AAPM TG 20, was based on the use of Faraday cups and calorimeters, whereas ionization chamber dosimetry received little attention. Following the trends in 'nuclear particle' radiotherapy, TG 20 included recommendations for specifying 'dose to tissue'. The lack of availability of a harmonized set of data for the different particles made this protocol to include data for stopping-powers and for the mean energy required to produce and ion pair in air, W air , from multiple authors, without enough attention being paid to their consistency. The increased focus into proton beams was materialized in the publication of the ECHED Code of Practice, dedicated exclusively to protons, where ionization dosimetry received more attention than in TG 20. It was not until the publication of the Supplement to the ECHED recommendations that ionization chambers having a 60 CO calibration factor were recommended as a reference detector for proton dosimetry, and data supplied for chambers with different wall materials. The emphasis on ionization chamber-based proton dosimetry was complemented with a recommendation for using water as dosimetry phantom material and the necessary data on tissue and water to air stopping-power ratios and W air . One of

Multiscale approach to equilibrating model polymer melts

DEFF Research Database (Denmark)

Svaneborg, Carsten; Ali Karimi-Varzaneh, Hossein; Hojdis, Nils

2016-01-01

We present an effective and simple multiscale method for equilibrating Kremer Grest model polymer melts of varying stiffness. In our approach, we progressively equilibrate the melt structure above the tube scale, inside the tube and finally at the monomeric scale. We make use of models designed...

Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

DEFF Research Database (Denmark)

Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru

2014-01-01

, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER...... was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related...... to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high...

Report on proton therapy according to good clinical practice at Hyogo Ion Beam Medical Center

International Nuclear Information System (INIS)

Murakami, Masao; Kagawa, Kazufumi; Hishikawa, Yoshio; Abe, Mitsuyuki

2002-01-01

The Hyogo Ion Beam Medical Center (HIBMC) is a hospital-based charged particle treatment facility. Having two treatment ion beams (proton and carbon) and five treatment rooms, it is a pioneer among particle institutes worldwide. In May 2001, proton therapy was started as a clinical study for patients with localized cancer originating in the head and neck, lung, liver, and prostate. The aim of this study was to investigate the safety, effectiveness, and stability of the treatment units and systems based on the evaluation of acute toxicity, tumor response, and working ratio of the machine, respectively. Six patients, including liver cancer in three, prostate cancer in two, and lung cancer in one, were treated. There was no cessation of therapy owing to machine malfunction. Full courses of proton therapy consisting of 154 portals in all six patients were given exactly as scheduled. None of the patients experienced severe acute reactions of more than grade 3 according to NCI-CTC criteria. Tumor response one month post-treatment was evaluable in five of the six patients, and was CR in 1 (prostate cancer), PR in 2 (lung cancer: 1, liver cancer: 1), and NC in 2 (liver cancer: 2). These results indicate that our treatment units and systems are safe and reliable enough for proton irradiation to be used for several malignant tumors localized in the body. (author)

Hydrogen/deuterium exchange of multiply-protonated cytochrome c ions

International Nuclear Information System (INIS)

Wood, T.D.; Guan, Ziqiang; O'Connor, P.B.

1995-01-01

Low resolution measurements show gaseous multiply-protonated cytochrome c ions undergo hydrogen/deuterium (H/D) exchange with pseudo first-order kinetics at three distinct exchange levels, suggesting the co-existence of gaseous protein conformations. Although exchange levels first increase with increasing charge values, they decrease at the highest charge values, consistent with solution-phase behavior of cytochrome c, where the native structure unfolds with decreasing pH until folding into a compact A-state at lowest pH. High resolution measurements indicate the presence of at least six H/D exchange levels. Infrared (IR) laser heating and fast collisions via quadrupolar excitation (QE) increase H/D exchange levels (unfolding) while charge-stripping ions to lower charge values can increase or decrease H/D exchange levels (unfolding or folding). Wolynes has suggested studying proteins in vacuo could play an important role in delineating the contributions various forces play in the protein folding process, provided appropriate comparisons can be made between gas-phase and solution-phase structures

Report on the FY 1999 investigational survey on the activation of oxygen electrode by ion implantation; 1999 nendo ion chunyuho ni yoru sanso denkyoku no kasseika ni kansuru kenkyu chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

The oxygen electrode is important as the base electrode for water electrolysis and fuel cell, but to move it, overvoltage (activated energy) in addition to equilibrium voltage is necessary, which leads to the lowering of energy efficiency. By forming the active spot by ion implantation, the lowering of overvoltage was studied. The implantation of Ru{sup +} ion in Ruthenium dioxide thin film electrode reduced the oxygen generating overvoltage by 15-20mV. Even in the oxygen reduction, activity was also increased. The chemical composition of thin film does not change by ion implantation. The increase in activity is based on a physical change which is called the surface defect formation. The layer of ion implantation is composed of microcrystals, which is thought to contribute to the formation of any active spot. Ions were implanted in Pt electrode as a practical use material, and even in the oxygen reduction of Pt, a possibility of heightening activity by ion implantation was admitted even in the oxygen reduction of Pt. The generation of high activity oxygen by ion plantation and development of oxygen reduction electrode were established as one method as a rule. (NEDO)

Differential Bystander Signaling Between Radioresistant Chondrosarcoma Cells and Fibroblasts After X-Ray, Proton, Iron Ion and Carbon Ion Exposures

Energy Technology Data Exchange (ETDEWEB)

Wakatsuki, Masaru, E-mail: wa@mbe.nifty.com [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts (United States); Magpayo, Nicole; Kawamura, Hidemasa; Held, Kathryn D. [Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts (United States)

2012-09-01

Purpose: Chondrosarcoma is well known as a radioresistant tumor, but the mechanisms underlying that resistance are still unclear. The bystander effect is well documented in the field of radiation biology. We investigated the bystander response induced by X-rays, protons, carbon ions, and iron ions in chondrosarcoma cells using a transwell insert co-culture system that precludes physical contact between targeted and bystander cells. Methods and Materials: Human chondrosarcoma cells were irradiated with 0.1-, 0.5-, 1-, and 2-Gy X-rays, protons, carbon ions or iron ions using a transwell insert co-culture system. Formation of micronuclei and p53 binding protein 1 staining in bystander and irradiated cells were analyzed and bystander signaling between mixed cultures of chondrosarcoma cells, and normal human skin fibroblasts was investigated. Results: In this study, we show that the fraction of cells with DNA damages in irradiated chondrosarcoma cells showed dose-dependent increases with all beams. However, the fraction of cells with DNA damages in all bystander chondrosarcoma cells did not show any change from the levels in control cells. In the bystander signaling between mixed cultures of chondrosarcoma cells and fibroblasts, the amount of micronucleus formation in all bystander chondrosarcoma cells co-cultured with irradiated fibroblasts were the same as the levels for control cells. However, all bystander fibroblasts co-cultured with irradiated chondrosarcoma cells showed significant increases in the fraction of micronucleated cells compared to the rate of control cells. Conclusions: We conclude that chondrosarcoma cells in the transwell insert co-culture system could release bystander stimulations but could not develop bystander responses.

Differential Bystander Signaling Between Radioresistant Chondrosarcoma Cells and Fibroblasts After X-Ray, Proton, Iron Ion and Carbon Ion Exposures

International Nuclear Information System (INIS)

Wakatsuki, Masaru; Magpayo, Nicole; Kawamura, Hidemasa; Held, Kathryn D.

2012-01-01

Purpose: Chondrosarcoma is well known as a radioresistant tumor, but the mechanisms underlying that resistance are still unclear. The bystander effect is well documented in the field of radiation biology. We investigated the bystander response induced by X-rays, protons, carbon ions, and iron ions in chondrosarcoma cells using a transwell insert co-culture system that precludes physical contact between targeted and bystander cells. Methods and Materials: Human chondrosarcoma cells were irradiated with 0.1-, 0.5-, 1-, and 2-Gy X-rays, protons, carbon ions or iron ions using a transwell insert co-culture system. Formation of micronuclei and p53 binding protein 1 staining in bystander and irradiated cells were analyzed and bystander signaling between mixed cultures of chondrosarcoma cells, and normal human skin fibroblasts was investigated. Results: In this study, we show that the fraction of cells with DNA damages in irradiated chondrosarcoma cells showed dose-dependent increases with all beams. However, the fraction of cells with DNA damages in all bystander chondrosarcoma cells did not show any change from the levels in control cells. In the bystander signaling between mixed cultures of chondrosarcoma cells and fibroblasts, the amount of micronucleus formation in all bystander chondrosarcoma cells co-cultured with irradiated fibroblasts were the same as the levels for control cells. However, all bystander fibroblasts co-cultured with irradiated chondrosarcoma cells showed significant increases in the fraction of micronucleated cells compared to the rate of control cells. Conclusions: We conclude that chondrosarcoma cells in the transwell insert co-culture system could release bystander stimulations but could not develop bystander responses.

Multiply charged ions of the oxygen - produced at interaction of laser radiation with two-element solids

International Nuclear Information System (INIS)

Bedilov, M.R.; Bedilov, R.M.; Kamalova, J.O.; Davletov, I.Yu.; Matnazarov, A.R.

2007-01-01

Full text: The interest to study of the oxygen multiply charged ions spectra produced at interaction laser radiation with one and two-element solids, is associate with possibility of creating laser and inertial thermonuclear syntheses, effective sources of multiply charged ions and nuclei atoms elements, plasma lasers, lasers on multiply charged transition, design of radiation-resistant materials and others. The present time many works is devoted to multiply charged ions, obtained from one element targets. Experimental results of study charge and energy spectra multiply charged ions of the oxygen, formed at interaction laser radiation with one and two-element solids are given in this work. Our experiments, we used installation, which is described in [1]. Neodymium laser had following parameters: wavelength 1.06 μm; intensity q = (0.1 h 1000) GW/sm 2 ; angle of incidence = 180. Were study one element Al, and two-element Al 2 O 3 , Y 2 O 3 targets by a diameter of 10 mm and thickness of 3 mm. Analysis obtained charge and energy spectra of multiply charged ions one (Al) and two-element (Al 2 O 3 , Y 2 O 3 ) targets depending on intensity of laser radiation and targets components reveal the following: - maximal charge number one element target (Al) at q 500 GW/sm 2 is equal Z max = 6 and all peaks corresponding to charge numbers Z = 1 - 6 well resolved, but two-element targets (Al 2 O 3 ) Z max ions Al decrease before 3. Also it is necessary to note that, Z max ions of the oxygen depend on target components. In case Al 2 O 3 and Y 2 O 3 maximal charge number of oxygen ions are equal Z max = 6 and 3, accordingly; - obtained charge and energy spectra of oxygen ions being included in two-element targets, are indicative of that, general regularities of the change Z max , E max and structures charge and energy spectra depending on q laser are saved. However they hang by target components; - common features and some differences of energy spectra multiply charged oxygen ions

Proton position near QB and coupling of electron and proton transfer in photosynthesis

International Nuclear Information System (INIS)

Belousov, R V; Poltev, S V; Kukushkin, A K

2003-01-01

We have calculated the energy levels and wavefunctions of a proton in a histidine (His)-plastoquinone (PQ) system in the reaction centre (RC) of photosystem 2 of higher plants and the RC of purple bacteria for different redox states of PQ Q B . For oxidized Q B , the proton is located near His. For once-reduced PQ, it is positioned in the middle between the nitrogen of His and the oxygen of PQ. For twofold-reduced PQ, the proton is localized near the oxygen of PQ. Using the values of total energy of the system in these states, we have also estimated the frequency of proton oscillations. On the basis of these results we propose a hypothesis about the coupling of electron-proton transfer

Calculation of rate coefficients of some proton-transfer ion-molecule reactions in weakly ionized gases

International Nuclear Information System (INIS)

Stiller, W.

1985-01-01

A classical collision theory is used to describe thermal bimolecular rate coefficeints for reaction between positive and negative ions and polar molecules in a carrier gas. Special attention is paid to ion-molecule reaction in which proton transfer occurs. These reactions play an important role in terrestrial plasma devices, in ionosphere, in planetary atmospheres and in interstellar matter. The equilibrium rate coefficients of the reactions are calculated based on a microscopic reactive cross section derived from a long distance polar molecule-ion potential. The results are compared with experimental values of afterglow measurements. (D.Gy.)

Cancer therapy with ions

International Nuclear Information System (INIS)

Mandrillon, P.

1993-01-01

The treatment of tumours with charged particles, ranging from protons to 'light ions' (Carbon, Oxygen, Neon) has many advantages, but up to now has been little used because of the absence of facilities. After the successful pioneering work carried out with accelerators built for physics research, machines dedicated to this new radiotherapy are planned or already in construction. The rationale for this new radiotherapy, the accelerators and the beam delivery systems needed are presented in this paper. (orig.)

Reversible solid oxide fuel cells (R-SOFCs) with chemically stable proton-conducting oxides

KAUST Repository

Bi, Lei

2015-07-01

Proton-conducting oxides offer a promising way of lowering the working temperature of solid oxide cells to the intermediate temperate range (500 to 700. °C) due to their better ionic conductivity. In addition, the application of proton-conducting oxides in both solid oxide fuel cells (SOFCs) and sold oxide electrolysis cells (SOECs) provides unique advantages compared with the use of conventional oxygen-ion conducting conductors, including the formation of water at the air electrode site. Since the discovery of proton conduction in some oxides about 30. years ago, the development of proton-conducting oxides in SOFCs and SOECs (the reverse mode of SOFCs) has gained increased attention. This paper briefly summarizes the development in the recent years of R-SOFCs with proton-conducting electrolytes, focusing on discussing the importance of adopting chemically stable materials in both fuel cell and electrolysis modes. The development of electrode materials for proton-conducting R-SOFCs is also discussed. © 2015 Elsevier B.V.

Gas phase reactions of protonated 1,3-diphenylpropyne and some isomeric [C15H13]+ ions

OpenAIRE

Bäther, Wolfgang; Kuck, Dietmar; Grützmacher, Hans-Friedrich

1985-01-01

Metastable (3-phenyl-2-propynyl)benzenium ions, generated by electron impact induced fragmentation from the appropriately substituted 1,4-dihydrobenzoic acid, react by loss of ·CH3 and C6H6. The study of deuterated derivatives reveals that hydrogen/deuterium exchanges involving all hydrogen and deuterium atoms precede the fragmentations. The results suggest a skeletal rearrangement by electrophilic ring-closure reactions giving rise to protonated phenylindene and protonated 9,10-methano-9,10-...

Structural, thermal and optical behavior of 84 MeV oxygen and 120 MeV silicon ions irradiated PES

International Nuclear Information System (INIS)

Samra, Kawaljeet Singh; Thakur, Sonika; Singh, Lakhwant

2011-01-01

In order to study structural, thermal and optical behavior, thin flat samples of polyethersulfone were irradiated with oxygen and silicon ions. The changes in properties were analyzed using different techniques viz: X-ray diffraction, thermo-gravimetric analysis, Fourier transform infrared, UV-visible and photoluminescence spectroscopy. A noticeable increase in the intensity of X-ray diffraction peaks was observed after irradiation with 84 MeV oxygen ions at low and medium fluences, which may be attributed to radiation-induced cross-linking in polymer. Fourier transform infrared and thermo-gravimetric analysis corroborated the results of X-ray diffraction analysis. No noticeable change in the Fourier transform infrared spectra of oxygen ion irradiated polyethersulfone were observed even at the highest fluence of 1 x 10 13 ions cm -2 , but after irradiation with silicon ions, a reduction in intensity of almost all characteristic bands was revealed. An increase in the activation energy of decomposition of polyethersulfone was observed after irradiation with 84 MeV oxygen ions up to medium fluences but degradation was revealed at higher fluences. Similar trends were observed by photoluminescence analysis.

ION-INDUCED PROCESSING OF COSMIC SILICATES: A POSSIBLE FORMATION PATHWAY TO GEMS

Energy Technology Data Exchange (ETDEWEB)

Jäger, C.; Sabri, T. [Max Planck Institute for Astronomy, Heidelberg, Laboratory Astrophysics and Cluster Physics Group, Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 3, D-07743 Jena (Germany); Wendler, E. [Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 3, D-07743 Jena (Germany); Henning, Th., E-mail: cornelia.jaeger@uni-jena.de [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

2016-11-01

Ion-induced processing of dust grains in the interstellar medium and in protoplanetary and planetary disks plays an important role in the entire dust cycle. We have studied the ion-induced processing of amorphous MgFeSiO{sub 4} and Mg{sub 2}SiO{sub 4} grains by 10 and 20 keV protons and 90 keV Ar{sup +} ions. The Ar{sup +} ions were used to compare the significance of the light protons with that of heavier, but chemically inert projectiles. The bombardment was performed in a two-beam irradiation chamber for in situ ion-implantation at temperatures of 15 and 300 K and Rutherford Backscattering Spectroscopy to monitor the alteration of the silicate composition under ion irradiation. A depletion of oxygen from the silicate structure by selective sputtering of oxygen from the surface of the grains was observed in both samples. The silicate particles kept their amorphous structure, but the loss of oxygen caused the reduction of ferrous (Fe{sup 2+}) ions and the formation of iron inclusions in the MgFeSiO{sub 4} grains. A few Si inclusions were produced in the iron-free magnesium silicate sample pointing to a much less efficient reduction of Si{sup 4+} and formation of metallic Si inclusions. Consequently, ion-induced processing of magnesium-iron silicates can produce grains that are very similar to the glassy grains with embedded metals and sulfides frequently observed in interplanetary dust particles and meteorites. The metallic iron inclusions are strong absorbers in the NIR range and therefore a ubiquitous requirement to increase the temperature of silicate dust grains in IR-dominated astrophysical environments such as circumstellar shells or protoplanetary disks.

Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions.

Science.gov (United States)

Zhang, Rui; Taddei, Phillip J; Fitzek, Markus M; Newhauser, Wayne D

2010-05-07

Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient's body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several simple analytical formulas previously developed for proton beams for their ability to calculate WET values for materials exposed to beams of protons, helium, carbon and iron ions. Experimentally measured heavy charged particle beam ranges and WET values from an iterative numerical method were compared with the WET values calculated by the analytical formulas. In most cases, the deviations were within 1 mm. We conclude that the analytical formulas originally developed for proton beams can also be used to calculate WET values for helium, carbon and iron ion beams with good accuracy.

Particles that fight cancer: the use of protons and carbon ions in cancer therapy

CERN Multimedia

CERN. Geneva

2014-01-01

Particles that fight cancer: the use of protons and carbon ions in cancer therapy Cancer is a major societal issue. A key challenge for cancer therapy is the complex and multifaceted nature of the disease, which calls for personalised treatment. Radiotherapy has been used to treat tumours for more than a century, and is still a staple in oncology: today, 50 % of cancer patients receive radiotherapy, half of them with curative intent. Hadrontherapy is one of the most technologically advanced methods of delivering radiation dose to the tumour while protecting surrounding healthy tissues. In addition, hadrontherapy can reach otherwise difficult to access deep-seated tumours and can be used for radio resistant tumours as in hypoxia. This year marks 60 years since the first patient was treated with protons in the US and 20 years since the use of carbon ions in Japan. Join us in learning about the journey of particle therapy in Japan and Europe, its challenges, clinical results and future prospects. Thursday 2...

Behavioral effects of heavy ions and protons and potential countermeasure agents

Science.gov (United States)

Vazquez, M.; Gatley, J.; Bruneus, M.; Koslosky, S.; Billups, A.

Space travel beyond the Earth's protective magnetic field (for example, to Mars) will involve exposure of astronauts to irradiation by high-energy nuclei such as 56 Fe, which are a component of galactic cosmic rays. These particles have high linear energy transfer (LET) and are expected to irreversibly damage cells they traverse. Exposure to HZE radiation may therefore cause progressive deterioration of brain function, adding to other inescapable damage involved in normal aging. We propose a study of the hypothesis that long-term behavioral alterations are induced after exposure of the brain to 1 GeV/n iron and silicon particles with fluences of 1 to 8 particles/cell targets. Previous studies support this notion but are not definitive, especially with regard to long-term effects. Our principal goal is to examine the neurological effects of high-LET radiation on C57BL/6 mice using a series of behavioral tests to unveil the temporal expression of altered behaviors in the radiation response, as well as the means, which can modulate these responses. The studies planned in this project are designed to: 1) Characterize the behavioral consequences after exposure to low-fluences of heavy ions and protons on C57BL/6 mice. The main behavioral endpoints to be used in these studies are locomotor activity to evaluate the integrity of striatal dopaminergic pathways, and spatial reference memory to probe hippocampal cholinergic pathways. 2) Characterize the neurochemical and structural changes induced by heavy ions and protons. 3) To develop countermeasures to protect neural cell populations exposed to low fluences of heavy ions and protons. The project will test methods to protect injured neural cells based on their molecular and cellular mechanisms that may regulate neural cell survival in the central nervous system. Among the methods that will be studied is the direct administration of neuroprotective molecules as well as the modulation of apoptotic pathways by pharmacological

Measurement of the relaxation rate of the magnetization in Mn12O12-acetate using proton NMR echo

Science.gov (United States)

Jang; Lascialfari; Borsa; Gatteschi

2000-03-27

We present a novel method to measure the relaxation rate W of the magnetization of Mn 12O (12)-acetate (Mn12) magnetic molecular cluster in its S = 10 ground state at low T. It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions.

Oxygen ion implantation induced microstructural changes and electrical conductivity in Bakelite RPC detector material

Energy Technology Data Exchange (ETDEWEB)

Kumar, K. V. Aneesh, E-mail: aneesh1098@gmail.com; Ravikumar, H. B., E-mail: hbr@physics.uni-mysore.ac.in [Department of Studies in Physics, University of Mysore, Mysore-570006 (India); Ranganathaiah, C., E-mail: cr@physics.uni-mysore.ac.in [Govt. Research Centre, Sahyadri Educational Institutions, Mangalore-575007 (India); Kumarswamy, G. N., E-mail: kumy79@gmail.com [Department of Studies in Physics, Amrita Vishwa Vidyapeetham, Bangalore-560035 (India)

2016-05-06

In order to explore the structural modification induced electrical conductivity, samples of Bakelite Resistive Plate Chamber (RPC) detector materials were exposed to 100 keV Oxygen ion in the fluences of 10{sup 12}, 10{sup 13}, 10{sup 14} and 10{sup 15} ions/cm{sup 2}. Ion implantation induced microstructural changes have been studied using Positron Annihilation Lifetime Spectroscopy (PALS) and X-Ray Diffraction (XRD) techniques. Positron lifetime parameters viz., o-Ps lifetime and its intensity shows the deposition of high energy interior track and chain scission leads to the formation of radicals, secondary ions and electrons at lower ion implantation fluences (10{sup 12} to10{sup 14} ions/cm{sup 2}) followed by cross-linking at 10{sup 15} ions/cm{sup 2} fluence due to the radical reactions. The reduction in electrical conductivity of Bakelite detector material is correlated to the conducting pathways and cross-links in the polymer matrix. The appropriate implantation energy and fluence of Oxygen ion on polymer based Bakelite RPC detector material may reduce the leakage current, improves the efficiency, time resolution and thereby rectify the aging crisis of the RPC detectors.

Detailed analysis of the cell-inactivation mechanism by accelerated protons and light ions

Czech Academy of Sciences Publication Activity Database

Kundrát, Pavel

2006-01-01

Roč. 51, - (2006), s. 1185-1199 ISSN 0031-9155 R&D Projects: GA ČR GA202/05/2728 Institutional research plan: CEZ:AV0Z10100502 Keywords : biological effects of ionizing particles * cell inactivation * modelling * protons * light ions * hadron radiotherapy Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 2.873, year: 2006

Integration and evaluation of automated Monte Carlo simulations in the clinical practice of scanned proton and carbon ion beam therapy.

Science.gov (United States)

Bauer, J; Sommerer, F; Mairani, A; Unholtz, D; Farook, R; Handrack, J; Frey, K; Marcelos, T; Tessonnier, T; Ecker, S; Ackermann, B; Ellerbrock, M; Debus, J; Parodi, K

2014-08-21

Monte Carlo (MC) simulations of beam interaction and transport in matter are increasingly considered as essential tools to support several aspects of radiation therapy. Despite the vast application of MC to photon therapy and scattered proton therapy, clinical experience in scanned ion beam therapy is still scarce. This is especially the case for ions heavier than protons, which pose additional issues like nuclear fragmentation and varying biological effectiveness. In this work, we present the evaluation of a dedicated framework which has been developed at the Heidelberg Ion Beam Therapy Center to provide automated FLUKA MC simulations of clinical patient treatments with scanned proton and carbon ion beams. Investigations on the number of transported primaries and the dimension of the geometry and scoring grids have been performed for a representative class of patient cases in order to provide recommendations on the simulation settings, showing that recommendations derived from the experience in proton therapy cannot be directly translated to the case of carbon ion beams. The MC results with the optimized settings have been compared to the calculations of the analytical treatment planning system (TPS), showing that regardless of the consistency of the two systems (in terms of beam model in water and range calculation in different materials) relevant differences can be found in dosimetric quantities and range, especially in the case of heterogeneous and deep seated treatment sites depending on the ion beam species and energies, homogeneity of the traversed tissue and size of the treated volume. The analysis of typical TPS speed-up approximations highlighted effects which deserve accurate treatment, in contrast to adequate beam model simplifications for scanned ion beam therapy. In terms of biological dose calculations, the investigation of the mixed field components in realistic anatomical situations confirmed the findings of previous groups so far reported only in

Effects of extracellular zinc ion on the rate of oxygen consumption of ...

African Journals Online (AJOL)

The inhibitory effect of extracellular zinc ion on the rate of oxygen consumption of rat brain mitochondria pre-incubated in 1.0 mM Ca2+EDTA were determined. There was a significant increase [P<0.01] in the rate of oxygen consumption in the rat brain mitochondria pre-incubated in 1.0 mM. Ca2+EDTA in a succinate ...

Database for inelastic collisions of lithium atoms with electrons, protons, and multiply charged ions

NARCIS (Netherlands)

Schweinzer, J; Brandenburg, R; Bray, [No Value; Hoekstra, R; Aumayr, F; Janev, RK; Winter, HP

New experimental and theoretical cross-section data for inelastic collision processes of Li atoms in the ground state and excited states (up to n = 4) with electrons, protons, and multiply charged ions have been reported since the database assembled by Wutte et al. [ATOMIC DATA AND NUCLEAR DATA

Statistical and off-equilibrium production of fragments in heavy ion collisions at intermediate energies; Production statistique et hors-equilibre de fragments dans les collisions d`ions lourdes aux energies intermediaires

Energy Technology Data Exchange (ETDEWEB)

Bocage, Frederic [Lab. de Physique Corpusculaire, Caen Univ., 14 - Caen (France)

1998-12-15

The study of reaction products, fragments and light charged particles, emitted during heavy-ion collisions at intermediate energies has shown the dominant binary dissipative character of the reaction, which is persisting for almost all impact parameters. However, in comparison with this purely binary process, an excess of nuclear matter is observed in-between the quasi-projectile and the quasi-target. To understand the mechanisms producing such an excess, this work studies more precisely the breakup in two fragments of the quasi-projectile formed in Xe+Sn, from 25 to 50 MeV/u, and Gd+C and Gd+U at 36 MeV/u. The data were obtained during the first INDRA experiment at GANIL. The angular distributions of the two fragments show the competition between statistical fission and non-equilibrated breakup of the quasi-projectile. In the second case, the two fragments are aligned along the separation axis of the two primary partners. The comparison of the fission directions and probabilities with statistical models allows us to measure the fission time, as well as the angular momentum, temperature and size of the fissioning residue. The relative velocities are compatible with Coulomb and thermal effects in the case of statistical fission and are found much higher for the breakup of a non-equilibrated quasi-projectile, which indicates that the projectile was deformed during interaction with the target. Such deformations should be compared with dynamical calculations in order to constrain the viscosity of nuclear matter and the parameters of the nucleon-nucleon interaction, (author) 148 refs., 77 figs., 11 tabs.

Indication of a Differential Freeze-out in Proton-Proton and Heavy-Ion Collisions at RHIC and LHC energies

CERN Document Server

Thakur, Dhananjaya; Garg, Prakhar; Sahoo, Raghunath; Cleymans, Jean

2016-01-01

The experimental data from the RHIC and LHC experiments of invariant pT spectra in A+A and p + p collisions are analysed with Tsallis distributions in different approaches. The information about the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocity for different particle species are obtained. Further, these parameters are studied as a function of the mass of the secondary particles. A mass-dependent differential freeze-out is observed which does not seem to distinguish between particles and their antiparticles. Further a mass-hierarchy in the radial flow is observed, meaning heavier particles suffer lower radial flow. Tsallis distribution function at finite chemical potential is used to study the mass dependence of chemical potential. The peripheral heavy-ion and proton-proton collisions at the same energies seem to be equivalent in terms of the extracted thermodynamic parameters.

A statistical study of ion energization at 1700 km in the auroral region

Directory of Open Access Journals (Sweden)

M. Hamrin

2002-12-01

Full Text Available We present a comprehensive overview of several potentially relevant causes for the oxygen energization in the auroral region. Data from the Freja satellite near 1700 km altitude are used for an unconditional statistical investigation. The data are obtained in the Northern Hemisphere during 21 months in the declining phase of the solar cycle. The importance of various wave types for the ion energization is statistically studied. We also investigate the correlation of ion heating with precipitating protons, accelerated auroral electrons, suprathermal electron bursts, the electron density variations, Kp index and solar illumination of the nearest conjugate ionosphere. We find that sufficiently strong broad-band ELF waves, electromagnetic ion cyclotron waves, and waves around the lower hybrid frequency are foremost associated with the ion heating. However, magnetosonic waves, with a sharp, lower frequency cutoff just below the proton gyrofrequency, are not found to contribute to the ion heating. In the absence of the first three wave emissions, transversely energized ions are rare. These wave types are approximately equally efficient in heating the ions, but we find that the main source for the heating is broadband ELF waves, since they are most common in the auroral region. We have also observed that the conditions for ion heating are more favourable for smaller ratios of the spectral densities SE /SB of the broadband ELF waves at the oxygen gyrofrequency.Key words. Ionosphere (auroral ionosphere; wave propogation Magnetospheric physics (electric fields

Proton transfer through hydrogen bonds in two-dimensional water layers: A theoretical study based on ab initio and quantum-classical simulations

International Nuclear Information System (INIS)

Bankura, Arindam; Chandra, Amalendu

2015-01-01

The dynamics of proton transfer (PT) through hydrogen bonds in a two-dimensional water layer confined between two graphene sheets at room temperature are investigated through ab initio and quantum-classical simulations. The excess proton is found to be mostly solvated as an Eigen cation where the hydronium ion donates three hydrogen bonds to the neighboring water molecules. In the solvation shell of the hydronium ion, the three coordinated water molecules with two donor hydrogen bonds are found to be properly presolvated to accept a proton. Although no hydrogen bond needs to be broken for transfer of a proton to such presolvated water molecules from the hydronium ion, the PT rate is still found to be not as fast as it is for one-dimensional chains. Here, the PT is slowed down as the probability of finding a water with two donor hydrogen bonds in the solvation shell of the hydronium ion is found to be only 25%-30%. The hydroxide ion is found to be solvated mainly as a complex anion where it accepts four H-bonds through its oxygen atom and the hydrogen atom of the hydroxide ion remains free all the time. Here, the presolvation of the hydroxide ion to accept a proton requires that one of its hydrogen bonds is broken and the proton comes from a neighboring water molecule with two acceptor and one donor hydrogen bonds. The coordination number reduction by breaking of a hydrogen bond is a slow process, and also the population of water molecules with two acceptor and one donor hydrogen bonds is only 20%-25% of the total number of water molecules. All these factors together tend to slow down the hydroxide ion migration rate in two-dimensional water layers compared to that in three-dimensional bulk water

Protonation of pyridine. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Zahran, N F; Ghoniem, H; Helal, A I [Physics Dept., Nuclear Research Center, AEA., Cairo, (Egypt); Rasheed, N [Nuclear Material Authority, Cairo, (Egypt)

1996-03-01

Field ionization mass spectra of pyridine is measured using 10{mu}m activated wire. protonation of pyridine, is observed as an intense peak in the mass spectra. Charge distribution of pyridine molecule is calculated using the modified neglect of diatomic overlap (MNDO) technique, and consequently proton attachment is proposed to be on the nitrogen atom. Temperature dependence of (M+H){sup +} ion is investigated and discussed. MNDO calculations of the protonated species are done, and the proton affinity of pyridine molecule is estimated. Time dependence of the field ionization process of pyridine and protonated ions are observed and discussed. 5 figs.

DISSOLVED OXYGEN REDUCTION IN THE DIII-D NEUTRAL BEAM ION SOURCE COOLING SYSTEM

International Nuclear Information System (INIS)

YIP, H.; BUSATH, J.; HARRISON, S.

2004-03-01

OAK-B135 Neutral beam ion sources (NBIS) are critical components for the neutral beam injection system supporting the DIII-D tokamak. The NBIS must be cooled with 3028 (ell)/m (800 gpm) of de-ionized and de-oxygenated water to protect the sources from overheating and failure. These ions sources are currently irreplaceable. Since the water cooled molybdenum components will oxidize in water almost instantaneously in the presence of dissolved oxygen (DO), de-oxygenation is extremely important in the NBIS water system. Under normal beam operation the DO level is kept below 5 ppb. However, during weeknights and weekends when neutral beam is not in operation, the average DO level is maintained below 10 ppb by periodic circulation with a 74.6 kW (100 hp) pump, which consumes significant power. Experimental data indicated evidence of continuous oxygen diffusion through non-metallic hoses in the proximity of the NBIS. Because of the intermittent flow of the cooling water, the DO concentration at the ion source(s) could be even higher than measured downstream, and hence the concern of significant localized oxidation/corrosion. A new 3.73 kW (5 hp) auxiliary system, installed in the summer of 2003, is designed to significantly reduce the peak and the time-average DO levels in the water system and to consume only a fraction of the power

Sputtering of Lunar Regolith Simulant by Protons and Multicharged Heavy Ions at Solar Wind Energies

International Nuclear Information System (INIS)

Meyer, Fred W.; Harris, Peter R.; Taylor, C.N.; Meyer, Harry M. III; Barghouty, N.; Adams, J. Jr.

2011-01-01

We report preliminary results on sputtering of a lunar regolith simulant at room temperature by singly and multiply charged solar wind ions using quadrupole and time-of-flight (TOF) mass spectrometry approaches. Sputtering of the lunar regolith by solar-wind heavy ions may be an important particle source that contributes to the composition of the lunar exosphere, and is a possible mechanism for lunar surface ageing and compositional modification. The measurements were performed in order to assess the relative sputtering efficiency of protons, which are the dominant constituent of the solar wind, and less abundant heavier multicharged solar wind constituents, which have higher physical sputtering yields than same-velocity protons, and whose sputtering yields may be further enhanced due to potential sputtering. Two different target preparation approaches using JSC-1A AGGL lunar regolith simulant are described and compared using SEM and XPS surface analysis.

Oxygen isotope exchange in La2NiO(4±δ).

Science.gov (United States)

Ananyev, M V; Tropin, E S; Eremin, V A; Farlenkov, A S; Smirnov, A S; Kolchugin, A A; Porotnikova, N M; Khodimchuk, A V; Berenov, A V; Kurumchin, E Kh

2016-04-07

Oxygen surface exchange kinetics and diffusion have been studied by the isotope exchange method with gas phase equilibration using a static circulation experimental rig in the temperature range of 600-800 °C and oxygen pressure range of 0.13-2.5 kPa. A novel model which takes into account distributions of the dissociative adsorption and incorporation rates has been developed. The rates of the elementary stages have been calculated. The rate-determining stages for a La2NiO(4±δ) polycrystalline specimen have been discussed. The diffusion activation energies calculated using the gas phase equilibration method (1.4 eV) differ significantly from those calculated using isotope exchange depth profiling (0.5-0.8 eV), which was attributed to the influence of different oxygen diffusion pathways.

Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

KAUST Repository

Alquaity, Awad; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

2016-01-01

chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

Simulation and dosimetric analysis of protons, {sup 4}He ions and {sup 12}C ions beams for brain neoplasm therapy; Simulacao e analise dosimetrica de feixes de protons e ions de {sup 4}He e {sup 12}C em tratamento de tumor cerebral

Energy Technology Data Exchange (ETDEWEB)

Santos, Guilherme M.; Mello, Victor Barreto Braga [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil); Mello Neto, Joao R.T. de [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

2016-07-01

This study aims to simulate protons, {sup 4}He ions and {sup 12}C ions beams, radiating the head of an average-sized man with the purpose of treating a hypothalamic tumor. GEANT4 was used to simulate the head (skin, skull and brain), and the beam, giving their characteristics and also the physical processes involved. The results sought herein are graphs of depth for relative dose for each of the three particles incident on the settings mentioned above. (author)

Oxygen isotopic fractionation during bacterial sulfate reduction

Science.gov (United States)

Balci, N.; Turchyn, A. V.; Lyons, T.; Bruchert, V.; Schrag, D. P.; Wall, J.

2006-12-01

Sulfur isotope fractionation during bacterial sulfate reduction (BSR) is understood to depend on a variety of environmental parameters, such as sulfate concentration, temperature, cell specific sulfate reduction rates, and the carbon substrate. What controls oxygen isotope fractionation during BSR is less well understood. Some studies have suggested that carbon substrate is important, whereas others concluded that there is a stoichiometric relationship between the fractionations of sulfur and oxygen during BSR. Studies of oxygen fractionation are complicated by isotopic equilibration between sulfur intermediates, particularly sulfite, and water. This process can modify the isotopic composition of the extracellular sulfate pool (δ18OSO4 ). Given this, the challenge is to distinguish between this isotopic equilibration and fractionations linked to the kinetic effects of the intercellular enzymes and the incorporation of sulfate into the bacterial cell. The δ18OSO4 , in concert with the sulfur isotope composition of sulfate (δ34SSO4), could be a powerful tool for understanding the pathways and environmental controls of BSR in natural systems. We will present δ18OSO4 data measured from batch culture growth of 14 different species of sulfate reducing bacteria for which sulfur isotope data were previously published. A general observation is that δ18OSO4 shows little isotopic change (kinetic effect during BSR and/or equilibration between sulfur intermediates and the isotopically light water (~-5‰) of the growth medium. Our present batch culture data do not allow us to convincingly isolate the magnitude and the controlling parameters of the kinetic isotope effect for oxygen. However, ongoing growth of mutant bacteria missing enzymes critical in the different steps of BSR may assist in this mission.

Double perovskite cathodes for proton-conducting ceramic fuel cells: are they triple mixed ionic electronic conductors?

Science.gov (United States)

Téllez Lozano, Helena; Druce, John; Cooper, Samuel J; Kilner, John A

2017-01-01

18 O and 2 H diffusion has been investigated at a temperature of 300 °C in the double perovskite material PrBaCo 2 O 5+ δ (PBCO) in flowing air containing 200 mbar of 2 H 2 16 O. Secondary ion mass spectrometry (SIMS) depth profiling of exchanged ceramics has shown PBCO still retains significant oxygen diffusivity (~1.3 × 10 -11 cm 2 s -1 ) at this temperature and that the presence of water ( 2 H 2 16 O), gives rise to an enhancement of the surface exchange rate over that in pure oxygen by a factor of ~3. The 2 H distribution, as inferred from the 2 H 2 16 O - SIMS signal, shows an apparent depth profile which could be interpreted as 2 H diffusion. However, examination of the 3-D distribution of the signal shows it to be nonhomogeneous and probably related to the presence of hydrated layers in the interior walls of pores and is not due to proton diffusion. This suggests that PBCO acts mainly as an oxygen ion mixed conductor when used in PCFC devices, although the presence of a small amount of protonic conductivity cannot be discounted in these materials.

Measurement of the Relaxation Rate of the Magnetization in Mn12O12 -Acetate Using Proton NMR Echo

International Nuclear Information System (INIS)

Jang, Z. H.; Lascialfari, A.; Borsa, F.; Gatteschi, D.

2000-01-01

We present a novel method to measure the relaxation rate W of the magnetization of Mn 12 O 12 -acetate (Mn12) magnetic molecular cluster in its S=10 ground state at low T . It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions. (c) 2000 The American Physical Society

Spot Scanning and Passive Scattering Proton Therapy: Relative Biological Effectiveness and Oxygen Enhancement Ratio in Cultured Cells.

Science.gov (United States)

Iwata, Hiromitsu; Ogino, Hiroyuki; Hashimoto, Shingo; Yamada, Maho; Shibata, Hiroki; Yasui, Keisuke; Toshito, Toshiyuki; Omachi, Chihiro; Tatekawa, Kotoha; Manabe, Yoshihiko; Mizoe, Jun-etsu; Shibamoto, Yuta

2016-05-01

To determine the relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and contribution of the indirect effect of spot scanning proton beams, passive scattering proton beams, or both in cultured cells in comparison with clinically used photons. The RBE of passive scattering proton beams at the center of the spread-out Bragg peak (SOBP) was determined from dose-survival curves in 4 cell lines using 6-MV X rays as controls. Survival of 2 cell lines after spot scanning and passive scattering proton irradiation was then compared. Biological effects at the distal end region of the SOBP were also investigated. The OER of passive scattering proton beams and 6 MX X rays were investigated in 2 cell lines. The RBE and OER values were estimated at a 10% cell survival level. The maximum degree of protection of radiation effects by dimethyl sulfoxide was determined to estimate the contribution of the indirect effect against DNA damage. All experiments comparing protons and X rays were made under the same biological conditions. The RBE values of passive scattering proton beams in the 4 cell lines examined were 1.01 to 1.22 (average, 1.14) and were almost identical to those of spot scanning beams. Biological effects increased at the distal end of the SOBP. In the 2 cell lines examined, the OER was 2.74 (95% confidence interval, 2.56-2.80) and 3.08 (2.84-3.11), respectively, for X rays, and 2.39 (2.38-2.43) and 2.72 (2.69-2.75), respectively, for protons (Pcells between X rays and protons). The maximum degree of protection was significantly higher for X rays than for proton beams (P<.05). The RBE values of spot scanning and passive scattering proton beams were almost identical. The OER was lower for protons than for X rays. The lower contribution of the indirect effect may partly account for the lower OER of protons. Copyright © 2016 Elsevier Inc. All rights reserved.

Geant4 simulation of clinical proton and carbon ion beams for the treatment of ocular melanomas with the full 3-D pencil beam scanning system

Energy Technology Data Exchange (ETDEWEB)

Farina, Edoardo; Riccardi, Cristina; Rimoldi, Adele; Tamborini, Aurora [University of Pavia and the INFN section of Pavia, via Bassi 6, 27100 Pavia (Italy); Piersimoni, Pierluigi [Division of Radiation Research, Loma Linda University, Loma Linda, CA 92354 (United States); Ciocca, Mario [Medical Physics Unit, CNAO Foundation, Strada Campeggi 53, 27100 Pavia (Italy)

2015-07-01

This work investigates the possibility to use carbon ion beams delivered with active scanning modality, for the treatment of ocular melanomas at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia. The radiotherapy with carbon ions offers many advantages with respect to the radiotherapy with protons or photons, such as a higher relative radio-biological effectiveness (RBE) and a dose release better localized to the tumor. The Monte Carlo (MC) Geant4 10.00 patch-03 toolkit is used to reproduce the complete CNAO extraction beam line, including all the active and passive components characterizing it. The simulation of proton and carbon ion beams and radiation scanned field is validated against CNAO experimental data. For the irradiation study of the ocular melanoma an eye-detector, representing a model of a human eye, is implemented in the simulation. Each element of the eye is reproduced with its chemical and physical properties. Inside the eye-detector a realistic tumor volume is placed and used as the irradiation target. A comparison between protons and carbon ions eye irradiations allows to study possible treatment benefits if carbon ions are used instead of protons. (authors)

Characterization of the proton irradiation induced luminescence of materials and application in radiation oncology dosimetry

Science.gov (United States)

Darafsheh, Arash; Zhang, Rongxiao; Kassaee, Alireza; Finlay, Jarod C.

2018-03-01

Visible light generated as the result of interaction of ionizing radiation with matter can be used for radiation therapy quality assurance. In this work, we characterized the visible light observed during proton irradiation of poly(methyl methacrylate) (PMMA) and silica glass fiber materials by performing luminescence spectroscopy. The spectra of the luminescence signal from PMMA and silica glass fibers during proton irradiation showed continuous spectra whose shape were different from that expected from Čerenkov radiation, indicating that Čerenkov radiation cannot be the responsible radioluminescence signal. The luminescence signal from each material showed a Bragg peak pattern and their corresponding proton ranges are in agreement with measurements performed by a standard ion chamber. The spectrum of the silica showed two peaks at 460 and 650 nm stem from the point defects of the silica: oxygen deficiency centers (ODC) and non-bridging oxygen hole centers (NBOHC), respectively. The spectrum of the PMMA fiber showed a continuous spectrum with a peak at 410 nm whose origin is connected with the fluorescence of the PMMA material. Our results are of interest for various applications based on imaging radioluminescent signal in proton therapy and will inform on the design of high-resolution fiber probes for proton therapy dosimetry.

Protonation of caffeine: A theoretical and experimental study

Energy Technology Data Exchange (ETDEWEB)

Bahrami, Hamed [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Tabrizchi, Mahmoud, E-mail: m-tabriz@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Farrokhpour, Hossein [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2013-03-29

Highlights: ► Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources. ► Experimental and theoretical evidence was collected to assign the observed peaks to caffeine related ionic species. ► A new concept of “internal proton affinity”, the protonation tendency for each atom in a molecule, was defined. - Abstract: Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources, corona discharge (CD) and UV photoionization. Three peaks were observed in ion mobility spectrum by simultaneously running the two ionization sources. Experimental and theoretical evidence was collected to link the observed peaks to caffeine related ionic species. One peak was attributed to the M{sup +} ion while the other two were assigned to different protonated isomers of caffeine. In the case of CD ionization source, it was observed that different sites of caffeine compete for protonation and their relative intensities, depends on the sample concentration as well as the nature of the reactant ions. The new concept of “internal proton affinity” (IPA) was defined to express the tendency of holding the added proton for each atom in a molecule.

Protonation of caffeine: A theoretical and experimental study

International Nuclear Information System (INIS)

Bahrami, Hamed; Tabrizchi, Mahmoud; Farrokhpour, Hossein

2013-01-01

Highlights: ► Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources. ► Experimental and theoretical evidence was collected to assign the observed peaks to caffeine related ionic species. ► A new concept of “internal proton affinity”, the protonation tendency for each atom in a molecule, was defined. - Abstract: Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources, corona discharge (CD) and UV photoionization. Three peaks were observed in ion mobility spectrum by simultaneously running the two ionization sources. Experimental and theoretical evidence was collected to link the observed peaks to caffeine related ionic species. One peak was attributed to the M + ion while the other two were assigned to different protonated isomers of caffeine. In the case of CD ionization source, it was observed that different sites of caffeine compete for protonation and their relative intensities, depends on the sample concentration as well as the nature of the reactant ions. The new concept of “internal proton affinity” (IPA) was defined to express the tendency of holding the added proton for each atom in a molecule

Doppler-shift proton fraction measurement on a CW proton injector

International Nuclear Information System (INIS)

Kamperschroer, J.H.; Sherman, J.D.; Zaugg, T.J.; Arvin, A.H.; Bolt, A.S.; Richards, M.C.

1998-01-01

A spectrometer/Optical Multi-channel Analyzer has been used to measure the proton fraction of the cw proton injector developed for the Accelerator Production of Tritium (APT) and the Low Energy Demonstration Accelerator (LEDA) at Los Alamos. This technique, pioneered by the Lawrence Berkeley National Laboratory (LBNL), was subsequently adopted by the international fusion community as the standard for determining the extracted ion fractions of neutral beam injectors. Proton fractions up to 95 ± 3% have been measured on the LEDA injector. These values are in good agreement with results obtained by magnetically sweeping the ion beam, collimated by a slit, across a Faraday cup. Since the velocity distribution of each beam species is measured, it also can be used to determine beam divergence. While divergence has not yet been ascertained due to the wide slit widths in use, non-Gaussian distributions have been observed during operation above the design-matched perveance. An additional feature is that the presence of extracted water ions can be observed. During ion source conditioning at 75 kV, an extracted water fraction > 30% was briefly observed

An acid-sensing ion channel from shark (Squalus acanthias) mediates transient and sustained responses to protons.

Science.gov (United States)

Springauf, Andreas; Gründer, Stefan

2010-03-01

Acid-sensing ion channels (ASICs) are proton-gated Na(+) channels. They are implicated in synaptic transmission, detection of painful acidosis, and possibly sour taste. The typical ASIC current is a transient, completely desensitizing current that can be blocked by the diuretic amiloride. ASICs are present in chordates but are absent in other animals. They have been cloned from urochordates, jawless vertebrates, cartilaginous shark and bony fish, from chicken and different mammals. Strikingly, all ASICs that have so far been characterized from urochordates, jawless vertebrates and shark are not gated by protons, suggesting that proton gating evolved relatively late in bony fish and that primitive ASICs had a different and unknown gating mechanism. Recently, amino acids that are crucial for the proton gating of rat ASIC1a have been identified. These residues are completely conserved in shark ASIC1b (sASIC1b), prompting us to re-evaluate the proton sensitivity of sASIC1b. Here we show that, contrary to previous findings, sASIC1b is indeed gated by protons with half-maximal activation at pH 6.0. sASIC1b desensitizes quickly but incompletely, efficiently encoding transient as well as sustained proton signals. Our results show that the conservation of the amino acids crucial for proton gating can predict proton sensitivity of an ASIC and increase our understanding of the evolution of ASICs.

Radial transport of storm time ring current ions

Science.gov (United States)

Lui, A. T. Y.

1993-01-01

Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer spacecraft, which monitored protons, helium ions, and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions. From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region can be accounted for by an inward displacement of the ring current population by 0.5 to 3.5 R(E). There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter time scale than that for a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations.

Tribological effects of oxygen ion implantation into stainless steel

International Nuclear Information System (INIS)

Evans, P.J.; Vilaithong, T.; Yu, L.D.; Monteiro, O.R.; Yu, K.M.; Brown, I.G.

2000-01-01

The formation of sub-surface oxide layers by hybrid metal-gas co-implantation into steel and other metals can improve their tribological properties. In this report, we compare the wear and friction performance of previously studied Al + O hybrid implants with that produced by single species oxygen ion (O + ) implantation under similar conditions. The substrates were AISI 304L stainless steel discs polished to a final mirror finish using 1 μm diamond paste, and the ion implantation was done using a conventional swept-beam technique at ion energies of 70 or 140 keV and doses of up to 1x10 17 cm -2 . The wear and friction behaviour of the implanted and unimplanted material was measured with a pin-on-disc tribometer. Here we describe the experimental procedure and results, and discuss the improvement relative to that achieved with surface layers modified by metal-gas co-implantation

Heavy Ion SEU Cross Section Calculation Based on Proton Experimental Data, and Vice Versa

CERN Document Server

Wrobel, F; Pouget, V; Dilillo, L; Ecoffet, R; Lorfèvre, E; Bezerra, F; Brugger, M; Saigné, F

2014-01-01

The aim of this work is to provide a method to calculate single event upset (SEU) cross sections by using experimental data. Valuable tools such as PROFIT and SIMPA already focus on the calculation of the proton cross section by using heavy ions cross-section experiments. However, there is no available tool that calculates heavy ion cross sections based on measured proton cross sections with no knowledge of the technology. We based our approach on the diffusion-collection model with the aim of analyzing the characteristics of transient currents that trigger SEUs. We show that experimental cross sections could be used to characterize the pulses that trigger an SEU. Experimental results allow yet defining an empirical rule to identify the transient current that are responsible for an SEU. Then, the SEU cross section can be calculated for any kind of particle and any energy with no need to know the Spice model of the cell. We applied our method to some technologies (250 nm, 90 nm and 65 nm bulk SRAMs) and we sho...

An optimized protocol for generation and analysis of Ion Proton sequencing reads for RNA-Seq.

Science.gov (United States)

Yuan, Yongxian; Xu, Huaiqian; Leung, Ross Ka-Kit

2016-05-26

Previous studies compared running cost, time and other performance measures of popular sequencing platforms. However, comprehensive assessment of library construction and analysis protocols for Proton sequencing platform remains unexplored. Unlike Illumina sequencing platforms, Proton reads are heterogeneous in length and quality. When sequencing data from different platforms are combined, this can result in reads with various read length. Whether the performance of the commonly used software for handling such kind of data is satisfactory is unknown. By using universal human reference RNA as the initial material, RNaseIII and chemical fragmentation methods in library construction showed similar result in gene and junction discovery number and expression level estimated accuracy. In contrast, sequencing quality, read length and the choice of software affected mapping rate to a much larger extent. Unspliced aligner TMAP attained the highest mapping rate (97.27 % to genome, 86.46 % to transcriptome), though 47.83 % of mapped reads were clipped. Long reads could paradoxically reduce mapping in junctions. With reference annotation guide, the mapping rate of TopHat2 significantly increased from 75.79 to 92.09 %, especially for long (>150 bp) reads. Sailfish, a k-mer based gene expression quantifier attained highly consistent results with that of TaqMan array and highest sensitivity. We provided for the first time, the reference statistics of library preparation methods, gene detection and quantification and junction discovery for RNA-Seq by the Ion Proton platform. Chemical fragmentation performed equally well with the enzyme-based one. The optimal Ion Proton sequencing options and analysis software have been evaluated.

Ion Prostate Irradiation (IPI) – a pilot study to establish the safety and feasibility of primary hypofractionated irradiation of the prostate with protons and carbon ions in a raster scan technique

International Nuclear Information System (INIS)

Habl, Gregor; Herfarth, Klaus; Hatiboglu, Gencay; Edler, Lutz; Uhl, Matthias; Krause, Sonja; Roethke, Matthias; Schlemmer, Heinz P; Hadaschik, Boris; Debus, Juergen

2014-01-01

Due to physical characteristics, ions like protons or carbon ions can administer the dose to the target volume more efficiently than photons since the dose can be lowered at the surrounding normal tissue. Radiation biological considerations are based on the assumption that the α/β value for prostate cancer cells is 1.5 Gy, so that a biologically more effective dose could be administered due to hypofractionation without increasing risks of late effects of bladder (α/β = 4.0) and rectum (α/β = 3.9). The IPI study is a prospective randomized phase II study exploring the safety and feasibility of primary hypofractionated irradiation of the prostate with protons and carbon ions in a raster scan technique. The study is designed to enroll 92 patients with localized prostate cancer. Primary aim is the assessment of the safety and feasibility of the study treatment on the basis of incidence grade III and IV NCI-CTC-AE (v. 4.02) toxicity and/or the dropout of the patient from the planned therapy due to any reason. Secondary endpoints are PSA-progression free survival (PSA-PFS), overall survival (OS) and quality-of-life (QoL). This pilot study aims at the evaluation of the safety and feasibility of hypofractionated irradiation of the prostate with protons and carbon ions in prostate cancer patients in an active beam technique. Additionally, the safety results will be compared with Japanese results recently published for carbon ion irradiation. Due to the missing data of protons in this hypofractionated scheme, an in depth evaluation of the toxicity will be created to gain basic data for a following comparison study with carbon ion irradiation. Clinical Trial Identifier: http://clinicaltrials.gov/show/NCT01641185 (clinicaltrials.gov)

Proton-Proton and Proton-Antiproton Colliders

CERN Document Server

Scandale, Walter

2014-01-01

In the last five decades, proton–proton and proton–antiproton colliders have been the most powerful tools for high energy physics investigations. They have also deeply catalyzed innovation in accelerator physics and technology. Among the large number of proposed colliders, only four have really succeeded in becoming operational: the ISR, the SppbarS, the Tevatron and the LHC. Another hadron collider, RHIC, originally conceived for ion–ion collisions, has also been operated part-time with polarized protons. Although a vast literature documenting them is available, this paper is intended to provide a quick synthesis of their main features and key performance.

New method for laser driven ion acceleration with isolated, mass-limited targets

International Nuclear Information System (INIS)

Paasch-Colberg, T.; Sokollik, T.; Gorling, K.; Eichmann, U.; Steinke, S.; Schnuerer, M.; Nickles, P.V.; Andreev, A.; Sandner, W.

2011-01-01

A new technique to investigate laser driven ion acceleration with fully isolated, mass-limited glass spheres with a diameter down to 8μm is presented. A Paul trap was used to prepare a levitating glass sphere for the interaction with a laser pulse of relativistic intensity. Narrow-bandwidth energy spectra of protons and oxygen ions have been observed and were attributed to specific acceleration field dynamics in case of the spherical target geometry. A general limiting mechanism has been found that explains the experimentally observed ion energies for the mass-limited target.

Some considerations regarding the applicability of the Saha-Eggert equation to quantitative SIMS analysis

International Nuclear Information System (INIS)

Werner, H.W.; Morgan, A.E.

1978-01-01

Some thoughts are presented on the physical processes described by the Saha-Eggert equation and some estimates are made regarding equilibration in a spike generated by ion bombardment. The influence of different parameters on the temperature determined from the Saha-Eggert equation is discussed. Section headings are: ionization in a spike; equilibration in a spike; factors influencing the ionization temperature (primary ion energy, secondary ion energies, presence of oxygen (an example shows the ionization temperature for uranium as a function of secondary ion energies and bombarding conditions)). (U.K.)

Radiobiological effects of heavy ions and protons. [on cells of mammals, bacteria and viruses

Science.gov (United States)

Ryzhov, N. I.; Vorozhtsova, S. V.; Krasavin, Y. A.; Mashinskaya, T. Y.; Savchenko, N. Y.; Fedorov, B. S.; Khlaponina, V. F.; Shelegedin, V. N.; Gut, L.; Sabo, L.

1974-01-01

Radiobiological effects of heavy ions and protons are studied on cells of mammals, bacteria, viruses and DNA of bacteria. Results show that the dose effect dependence bears an exponential character; the reduction of RBE as LET of particle increases reflects the different character of microdistribution of absorbed energy in biological objects with different levels of biological organization.

Evaluation of beam delivery and ripple filter design for non-isocentric proton and carbon ion therapy.

Science.gov (United States)

Grevillot, L; Stock, M; Vatnitsky, S

2015-10-21

This study aims at selecting and evaluating a ripple filter design compatible with non-isocentric proton and carbon ion scanning beam treatment delivery for a compact nozzle. The use of non-isocentric treatments when the patient is shifted as close as possible towards the nozzle exit allows for a reduction in the air gap and thus an improvement in the quality of scanning proton beam treatment delivery. Reducing the air gap is less important for scanning carbon ions, but ripple filters are still necessary for scanning carbon ion beams to reduce the number of energy steps required to deliver homogeneous SOBP. The proper selection of ripple filters also allows a reduction in the possible transverse and depth-dose inhomogeneities that could appear in non-isocentric conditions in particular. A thorough review of existing ripple filter designs over the past 16 years is performed and a design for non-isocentric treatment delivery is presented. A unique ripple filter quality index (QIRiFi) independent of the particle type and energy and representative of the ratio between energy modulation and induced scattering is proposed. The Bragg peak width evaluated at the 80% dose level (BPW80) is proposed to relate the energy modulation of the delivered Bragg peaks and the energy layer step size allowing the production of homogeneous SOBP. Gate/Geant4 Monte Carlo simulations have been validated for carbon ion and ripple filter simulations based on measurements performed at CNAO and subsequently used for a detailed analysis of the proposed ripple filter design. A combination of two ripple filters in a series has been validated for non-isocentric delivery and did not show significant transverse and depth-dose inhomogeneities. Non-isocentric conditions allow a significant reduction in the spot size at the patient entrance (up to 350% and 200% for protons and carbon ions with range shifter, respectively), and therefore in the lateral penumbra in the patients.

A selected ion flow tube study of the ion molecule association reactions of protonated (MH+), nitrosonated (MNO+) and dehydroxidated (M-OH)(+) carboxylic acids (M) with H2O

Czech Academy of Sciences Publication Activity Database

Brůhová Michalčíková, R.; Španěl, Patrik

2014-01-01

Roč. 368, JUL 2014 (2014), s. 15-22 ISSN 1387-3806 R&D Projects: GA ČR GA13-28882S Institutional support: RVO:61388955 Keywords : ion molecule reactions * proton transfer * selected ion flow tube mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.972, year: 2014

An automated technique for measuring deltaD and delta18O values of porewater by direct CO2 and H2 equilibration.

Science.gov (United States)

Koehler, G; Wassenaar, L I; Hendry, M J

2000-11-15

The stable-oxygen and -hydrogen isotopic values (deltaD, delta18O) of porewater in geologic media are commonly determined on water obtained by extraction techniques such as centrifugation, mechanical squeezing, vacuum heating and cryogenic microdistillation, and azeotropic distillation. Each of these techniques may cause isotopic fractionation as part the extraction process and each is laborious. Here we demonstrate a new approach to obtain automated, high-precision deltaD and delta18O measurements of porewater in geologic sediments by direct H2- and CO2-porewater equilibration using a modified commercial CO2-water equilibrator. This technique provides an important and cost-effective improvement over current extraction methods, because many samples can be rapidly analyzed with minimal handling, thereby reducing errors and potential for isotopic fractionation. The precision and accuracy of direct H2- and CO2-porewater equilibration is comparable to or better than current porewater extraction methods. Finally, the direct equilibration technique allows investigators to obtain high-resolution (cm scale) porewater deltaD and delta18O profiles using cores from individual boreholes, eliminating the need for costly piezometers or conventional porewater extractions.

Protonated ions as systemic trapping agents for noble gases: From electronic structure to radiative association.

Science.gov (United States)

Ozgurel, O; Pauzat, F; Pilmé, J; Ellinger, Y; Bacchus-Montabonel, M-C; Mousis, O

2017-10-07

The deficiencies of argon, krypton, and xenon observed in the atmosphere of Titan as well as anticipated in some comets might be related to a scenario of sequestration by H 3 + in the gas phase at the early evolution of the solar nebula. The chemical process implied is a radiative association, evaluated as rather efficient in the case of H 3 + , especially for krypton and xenon. This mechanism of chemical trapping might not be limited to H 3 + only, considering that the protonated ions produced in the destruction of H 3 + by its main competitors present in the primitive nebula, i.e., H 2 O, CO, and N 2 , might also give stable complexes with the noble gases. However the effective efficiency of such processes is still to be proven. Here, the reactivity of the noble gases Ar, Kr, and Xe, with all protonated ions issued from H 2 O, CO, and N 2 , expected to be present in the nebula with reasonably high abundances, has been studied with quantum simulation method dynamics included. All of them give stable complexes and the rate coefficients of their radiative associations range from 10 -16 to 10 -19 cm 3 s -1 , which is reasonable for such reactions and has to be compared to the rates of 10 -16 to 10 -18 cm 3 s -1 , obtained with H 3 + . We can consider this process as universal for all protonated ions which, if present in the primitive nebula as astrophysical models predict, should act as sequestration agents for all three noble gases with increasing efficiency from Ar to Xe.

Extraction of low-energy negative oxygen ions for thin film formation

International Nuclear Information System (INIS)

Vasquez, M. Jr.; Sasaki, D.; Kasuya, T.; Wada, M.; Maeno, S.

2011-01-01

Coextraction of low-energy positive and negative ions were performed using a plasma sputter-type ion source system driven by a 13.56 MHz radio frequency (rf) power. Titanium (Ti) atoms were sputtered out from a target and the sputtered neutrals were postionized in oxygen/argon (O 2 /Ar) plasma prior to extraction. The negative O ions were surface-produced and self-extracted. Mass spectral analyses of the extracted ion beams revealed the dependence of the ion current on the incident rf power, induced target bias and O 2 /Ar partial pressure ratio. Ti + current was found to be dependent on Ar + current and reached a saturation value with increasing O 2 partial pressure while the O - current showed a peak current at around 1:9 O 2 /Ar partial pressure ratio. Ti + current was several orders of magnitude higher than that of the O - current.

Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

Energy Technology Data Exchange (ETDEWEB)

Raza, Rizwan, E-mail: razahussaini786@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Ajmal Khan, M.; Abbas, Ghazanfar; Alvi, Farah; Yasir Rafique, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Sherazi, Tauqir A. [Department of Chemistry, COMSATS Institute of Information Technology, Abbotabad 22060 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) center, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Mohsin, Munazza [Department of Physics, Lahore College for Women University, Lahore, 54000 (Pakistan); Javed, Muhammad Sufyan [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Zhu, Bin, E-mail: binzhu@kth.se, E-mail: zhubin@hubu.edu.cn [Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science/Faculty of Computer and Information, Hubei University, Wuhan, Hubei 430062 (China)

2015-11-02

In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport number of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.

Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

Science.gov (United States)

Raza, Rizwan; Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Sherazi, Tauqir A.; Ajmal Khan, M.; Abbas, Ghazanfar; Shakir, Imran; Mohsin, Munazza; Alvi, Farah; Javed, Muhammad Sufyan; Yasir Rafique, M.; Zhu, Bin

2015-11-01

In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O-2 (oxygen ions) and H+ (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport number of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm2, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.

Oxygen adsorption on Cu(111) using low energy ion scattering spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, F.M.; Yao, J.; Shen, Y.G.; King, B.V.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics

1993-12-31

The surface structure and oxygen adsorption of Cu(l 11) have been studied by 2 keV Li{sup +}, He{sup +} and Ar{sup +} ion scattering . Incident and azimuthal dependences were measured for the clean and O-covered surfaces, and the surface geometry was analysed on the basis of the shadowing features. Experimental results under different oxygen exposures at room temperature showed that the Cu(l 11) surface undergoes a roughening transition and results in a reconstruction where Cu atoms are vertically displaced by about 0.23 Angstroms. 4 refs., 4 figs.

Oxygen adsorption on Cu(111) using low energy ion scattering spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, F M; Yao, J; Shen, Y G; King, B V; O` Connor, D J [Newcastle Univ., NSW (Australia). Dept. of Physics

1994-12-31

The surface structure and oxygen adsorption of Cu(l 11) have been studied by 2 keV Li{sup +}, He{sup +} and Ar{sup +} ion scattering . Incident and azimuthal dependences were measured for the clean and O-covered surfaces, and the surface geometry was analysed on the basis of the shadowing features. Experimental results under different oxygen exposures at room temperature showed that the Cu(l 11) surface undergoes a roughening transition and results in a reconstruction where Cu atoms are vertically displaced by about 0.23 Angstroms. 4 refs., 4 figs.

Oxygen adsorption on Cu(111) using low energy ion scattering spectroscopy

International Nuclear Information System (INIS)

Zhang, F.M.; Yao, J.; Shen, Y.G.; King, B.V.; O'Connor, D.J.

1993-01-01

The surface structure and oxygen adsorption of Cu(l 11) have been studied by 2 keV Li + , He + and Ar + ion scattering . Incident and azimuthal dependences were measured for the clean and O-covered surfaces, and the surface geometry was analysed on the basis of the shadowing features. Experimental results under different oxygen exposures at room temperature showed that the Cu(l 11) surface undergoes a roughening transition and results in a reconstruction where Cu atoms are vertically displaced by about 0.23 Angstroms. 4 refs., 4 figs

Proton-induced knockout reactions with netron-rich oxygen isotopes at R{sup 3}B

Energy Technology Data Exchange (ETDEWEB)

Atar, Leyla [IKP, TU Darmstadt (Germany); GSI (Germany); Collaboration: R3B-Collaboration

2014-07-01

Proton-induced knockout reactions are one of the main goal of the experimental program at the future R{sup 3}B (Reactions with Relativistic Radioactive Beams) Experiment at FAIR. It allows us to obtain spectroscopic information about valence and deeply bound single-nucleon states and to study their evolution over a large variation in isospin. Recent studies have shown that the occupancies of loosely bound valence nucleons in neutron- or proton-rich nuclei have a spectroscopic factor close to unity, whereas single-particle strength for deeply bound nucleons is suppressed in isospin asymmetric systems compared to the predictions of the many-body shell model. Further experimental and theoretical studies are needed for a qualitative and quantitative understanding. For this aim a series of measurements have been performed on the complete oxygen isotopic chain using the existing experimental setup LAND/R{sup 3}B at GSI. We present the main scientific goals, the concepts of the experiment and the preliminary results.

Rapid spatial equilibration of a particle in a box.

Science.gov (United States)

Malabarba, Artur S L; Linden, Noah; Short, Anthony J

2015-12-01

We study the equilibration behavior of a quantum particle in a one-dimensional box, with respect to a coarse-grained position measurement (whether it lies in a certain spatial window or not). We show that equilibration in this context indeed takes place and does so very rapidly, in a time comparable to the time for the initial wave packet to reach the edges of the box. We also show that, for this situation, the equilibration behavior is relatively insensitive to the precise choice of position measurements or initial condition.

Thermal lattice Boltzmann simulation for multispecies fluid equilibration

International Nuclear Information System (INIS)

Vahala, Linda; Wah, Darren; Vahala, George; Carter, Jonathan; Pavlo, Pavol

2000-01-01

The equilibration rate for multispecies fluids is examined using thermal lattice Boltzmann simulations. Two-dimensional free-decay simulations are performed for effects of velocity shear layer turbulence on sharp temperature profiles. In particular, parameters are so chosen that the lighter species is turbulent while the heavier species is laminar--and so its vorticity layers would simply decay and diffuse in time. With species coupling, however, there is velocity equilibration followed by the final relaxation to one large co- and one large counter-rotating vortex. The temperature equilibration proceeds on a slower time scale and is in good agreement with the theoretical order of magnitude estimate of Morse [Phys. Fluids 6, 1420 (1963)]. (c) 2000 The American Physical Society

Thermal lattice Boltzmann simulation for multispecies fluid equilibration

Energy Technology Data Exchange (ETDEWEB)

Vahala, Linda [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States); Wah, Darren [Department of Physics, William and Mary College, Williamsburg, Virginia 23187 (United States); Vahala, George [Department of Physics, William and Mary College, Williamsburg, Virginia 23187 (United States); Carter, Jonathan [NERSC, Lawrence Berkeley Laboratory, Berkeley, California 97320 (United States); Pavlo, Pavol [Institute of Plasma Physics, Czech Academy of Science, Praha 8, (Czech Republic)

2000-07-01

The equilibration rate for multispecies fluids is examined using thermal lattice Boltzmann simulations. Two-dimensional free-decay simulations are performed for effects of velocity shear layer turbulence on sharp temperature profiles. In particular, parameters are so chosen that the lighter species is turbulent while the heavier species is laminar--and so its vorticity layers would simply decay and diffuse in time. With species coupling, however, there is velocity equilibration followed by the final relaxation to one large co- and one large counter-rotating vortex. The temperature equilibration proceeds on a slower time scale and is in good agreement with the theoretical order of magnitude estimate of Morse [Phys. Fluids 6, 1420 (1963)]. (c) 2000 The American Physical Society.

Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

International Nuclear Information System (INIS)

Wetteland, C. J.; Field, K. G.; Gerczak, T. J.; Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

2013-01-01

The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150μA of proton current from the source, with over 70μA on the target stage. However, beam fluxes above ∼1×10 17 /m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

Ion Colliders

CERN Document Server

Fischer, W

2014-01-01

High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.

Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

KAUST Repository

Kim, Daesang

2015-07-01

Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

KAUST Repository

Kim, Daesang; Rizzi, Francesco; Cheng, Kwok Wah; Han, Jie; Bisetti, Fabrizio; Knio, Omar Mohamad

2015-01-01

Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

A multi-satellite study of accelerated ionospheric ion beams above the polar cap

Directory of Open Access Journals (Sweden)

R. Maggiolo

2006-07-01

Full Text Available This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5–9 RE. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio EO+ / EH+, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity. In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5 Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H+ and O+. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability.

Enhancement of oxygen reduction at Fe tetrapyridyl porphyrin by pyridyl-N coordination to transition metal ions

International Nuclear Information System (INIS)

Maruyama, Jun; Baier, Claudia; Wolfschmidt, Holger; Bele, Petra; Stimming, Ulrich

2012-01-01

One of the promising candidates as noble-metal-free electrode catalysts for polymer electrolyte fuel cells (PEFCs) is a carbon material with nitrogen atoms coordinating iron ions embedded on the surface (Fe-N x moiety) as the active site, although the activity is insufficient compared to conventional platinum-based electrocatalysts. In order to obtain fundamental information on the activity enhancement, a simple model of the Fe-N x active site was formed by adsorbing 5,10,15,20-Tetrakis(4-pyridyl)-21H,23H-porphine iron(III) chloride (FeTPyPCl) on the basal plane of highly oriented pyrolytic graphite (HOPG), and cathodic oxygen reduction was investigated on the surface in 0.1 M HClO 4 . The catalytic activity for oxygen reduction was enhanced by loading transition metal ions (Co 2+ , Ni 2+ , Cu 2+ ) together with FeTPyPCl. The X-ray photoelectron spectrum of the surface suggested that the metal was coordinated by the pyridine-N. The enhancement effect of the transition metals was supported by two different measurements: oxygen reduction at HOPG in 0.1 M HClO 4 dissolving FeTPyPCl and the metal ions; oxygen reduction in 0.1 M HClO 4 at the subsequently well-rinsed and dried HOPG. The ultraviolet–visible spectrum for the solution also suggested the coordination between the pyridyl-N and the metal ions. The oxygen reduction enhancement was attributed to the electronic interaction between the additional transition metal and the Fe center of the porphyrin through the coordination bonds. These results implied that the improvement of the activity of the noble-metal-free catalyst would be possible by the proper introduction of the transition metal ions around the active site.

Measurement of the Relaxation Rate of the Magnetization in Mn{sub 12}O{sub 12} -Acetate Using Proton NMR Echo

Energy Technology Data Exchange (ETDEWEB)

Jang, Z. H. [Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Lascialfari, A. [Dipartimento di Fisica ' ' A. Volta' ' e Unita' , INFM di Pavia, Via Bassi 6, 27100 Pavia, (Italy); Borsa, F. [Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Dipartimento di Fisica ' ' A. Volta' ' e Unita' , INFM di Pavia, Via Bassi 6, 27100 Pavia, (Italy); Gatteschi, D. [Department of Chemistry, University of Florence, Via Maragliano 77, 50144 Firenze, (Italy)

2000-03-27

We present a novel method to measure the relaxation rate W of the magnetization of Mn{sub 12}O {sub 12} -acetate (Mn12) magnetic molecular cluster in its S=10 ground state at low T . It is based on the observation of an exponential growth in time of the proton NMR signal during the thermal equilibration of the magnetization of the molecules. We can explain the novel effect with a simple model which relates the intensity of the proton echo signal to the microscopic reversal of the magnetization of each individual Mn12 molecule during the equilibration process. The method should find wide application in the study of magnetic molecular clusters in off-equilibrium conditions. (c) 2000 The American Physical Society.

LHCf Letter of Intent for a p-Pb run. A precise study of forward physics in √s_NN= 4.4 TeV proton-Lead ion collisions with LHCf at the LHC

CERN Document Server

Adriani, O

2011-01-01

The LHCf detectors were installed in the TAN regions on both sides of IP1 at the beginning of the LHC run in 2009. The goal of the experiment is the measurement of neutral particle production at very high pseudo-rapidity values (η > 8.4) in proton-proton (pp) and proton-ion (pA) collisions. Until now data have been for two different physics cases, pp interactions at 900 GeV and 7 TeV center of mass energy. These data are extremely useful for the calibration of hadronic interaction models used for the study of the development of atmospheric showers, identified also as Extensive Air Showers (EAS), produced by extremely energetic cosmic-ray (CR) particles interacting with the atmospheric gas. Anyway the study of only the pp system in not enough to have a complete picture of hadronic interactions in atmosphere, where interactions involve mainly nitrogen and oxygen nuclei which can differ in important aspects with respect to the more simple case of pp interaction. A marked reduction of cross section valu...

Heavy-ion induced secondary electron emission from Mg, Al, and Si partially covered with oxygen

International Nuclear Information System (INIS)

Weng, J; Veje, E.

1984-01-01

We have bombarded Mg, Al, and Si with 80 keV Ar + ions and measured the secondary electron emission yields at projectile incidence angles from 0 0 to 85 0 , with oxygen present at the target as well as under UHV conditions. The total secondary electron emission yields are found to depend fairly much on the amount of oxygen present. The three elements studied show relatively large individual variations. For all three elements, and with as well as without oxygen present, the relative secondary electron emission yield is observed to vary as 1/cos v, where v is the angle of incidence of the projectiles. This seems to indicate that the secondary electron production is initiated uniformly along the projectile path in the solid, in a region close to the surface. The results are discussed, and it is tentatively suggested, that the increase in secondary electron emission, caused by the presence of oxygen, originates from neutralization of sputtered oxygen, which initially is sitting as O 2- ions. (orig.)

Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plate detectors for protons, deuterons, and alpha particles.

Science.gov (United States)

Freeman, C G; Fiksel, G; Stoeckl, C; Sinenian, N; Canfield, M J; Graeper, G B; Lombardo, A T; Stillman, C R; Padalino, S J; Mileham, C; Sangster, T C; Frenje, J A

2011-07-01

A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at the University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW.

Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plate detectors for protons, deuterons, and alpha particles

Energy Technology Data Exchange (ETDEWEB)

Freeman, C. G.; Canfield, M. J.; Graeper, G. B.; Lombardo, A. T.; Stillman, C. R.; Padalino, S. J. [Physics Department, SUNY Geneseo, Geneseo, New York 14454 (United States); Fiksel, G.; Stoeckl, C.; Mileham, C.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Sinenian, N.; Frenje, J. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-07-15

A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW.

Surface modification effects of fluorine-doped tin dioxide by oxygen plasma ion implantation

Science.gov (United States)

Tang, Peng; Liu, Cai; Zhang, Jingquan; Wu, Lili; Li, Wei; Feng, Lianghuan; Zeng, Guanggen; Wang, Wenwu

2018-04-01

SnO2:F (FTO), as a kind of transparent conductive oxide (TCO), exhibits excellent transmittance and conductivity and is widely used as transparency electrodes in solar cells. It's very important to modifying the surface of FTO for it plays a critical role in CdTe solar cells. In this study, modifying effects of oxygen plasma on FTO was investigated systematically. Oxygen plasma treatment on FTO surface with ion accelerating voltage ranged from 0.4 kV to 1.6 kV has been processed. The O proportion of surface was increased after ion implantation. The Fermi level of surface measurement by XPS valance band spectra was lowered as the ion accelerating voltage increased to 1.2 kV and then raised as accelerating voltage was elevated to 1.6 kV. The work function measured by Kelvin probe force microscopy increased after ion implanting, and it was consistent with the variation of Fermi level. The change of energy band structure of FTO surface mainly originated from the surface composition variation. As FTO conduction was primarily due to oxyanion hole, the carrier was electron and its concentration was reduced while O proportion was elevated at the surface of FTO, as a result, the Fermi level lowered and the work function was enlarged. It was proved that oxygen plasma treatment is an effective method to modulate the energy band structure of the surface as well as other properties of FTO, which provides much more space for interface and surface modification and then photoelectric device performance promotion.

Equilibration and hydrodynamics at strong and weak coupling

Science.gov (United States)

van der Schee, Wilke

2017-11-01

We give an updated overview of both weak and strong coupling methods to describe the approach to a plasma described by viscous hydrodynamics, a process now called hydrodynamisation. At weak coupling the very first moments after a heavy ion collision is described by the colour-glass condensate framework, but quickly thereafter the mean free path is long enough for kinetic theory to become applicable. Recent simulations indicate thermalization in a time t ∼ 40(η / s) 4 / 3 / T [L. Keegan, A. Kurkela, P. Romatschke, W. van der Schee, Y. Zhu, Weak and strong coupling equilibration in nonabelian gauge theories, JHEP 04 (2016) 031. arxiv:arXiv:1512.05347, doi:10.1007/JHEP04(2016)031], with T the temperature at that time and η / s the shear viscosity divided by the entropy density. At (infinitely) strong coupling it is possible to mimic heavy ion collisions by using holography, which leads to a dual description of colliding gravitational shock waves. The plasma formed hydrodynamises within a time of 0.41/T recent extension found corrections to this result for finite values of the coupling, when η / s is bigger than the canonical value of 1/4π, which leads to t ∼ (0.41 + 1.6 (η / s - 1 / 4 π)) / T [S. Grozdanov, W. van der Schee, Coupling constant corrections in holographic heavy ion collisions, arxiv:arXiv:1610.08976]. Future improvements include the inclusion of the effects of the running coupling constant in QCD.

Kinetics and mechanism of aquation and formation reactions of carbonato complexes. XII. Deuterium solvent isotope effect on the rate of acid-catalyzed decarboxylation of the carbonatobis (ethylenediamine) cobalt(III) complex ion. A mechanistic reappraisal

International Nuclear Information System (INIS)

Harris, G.M.; Hyde, K.E.

1978-01-01

A recent study of the acid-catalyzed decarboxylation of the carbonatotetrakis(pyridine)cobalt(III) complex ion showed there to be rate acceleration in D 2 O solvent, consistent with a proton-preequilibration mechanism. This observation directly contradicts the results of a similar study made some years ago of the analogous ion, carbonatobis(ethylenediamine)cobalt(III), for which there appeared to be deceleration in D 2 O solvent. A reinvestigation of the latter reaction over a much wider acidity range has now shown the earlier work to be in error. The previously proposed generalized mechanism for aquation of chelated carbonato complex ions of the form CoN 4 CO 3 + (N 4 identical with various tetramine ligand groupings of uni-, bi-, or quadridentate type) has thus been revised to include a proton equilibration step. An unexpected complication arises in the interpretation of the data for the bis(ethylenediamine) complex ion in the acidity range 0.1 + ] + ] term, overtakes and exceeds the true first-order rate constant for CO 2 release. The interesting implications of this unusual first-order successive reaction system are fully explored in the context of the present study

The Acceleration of Thermal Protons and Minor Ions at a Quasi-Parallel Interplanetary Shock

Science.gov (United States)

Giacalone, J.; Lario, D.; Lepri, S. T.

2017-12-01

We compare the results from self-consistent hybrid simulations (kinetic ions, massless fluid electrons) and spacecraft observations of a strong, quasi-parallel interplanetary shock that crossed the Advanced Composition Explorer (ACE) on DOY 94, 2001. In our simulations, the un-shocked plasma-frame ion distributions are Maxwellian. Our simulations include protons and minor ions (alphas, 3He++, and C5+). The interplanetary shock crossed both the ACE and the Wind spacecraft, and was associated with significant increases in the flux of > 50 keV/nuc ions. Our simulation uses parameters (ion densities, magnetic field strength, Mach number, etc.) consistent with those observed. Acceleration of the ions by the shock, in a manner similar to that expected from diffusive shock acceleration theory, leads to a high-energy tail in the distribution of the post-shock plasma for all ions we considered. The simulated distributions are directly compared to those observed by ACE/SWICS, EPAM, and ULEIS, and Wind/STICS and 3DP, covering the energy range from below the thermal peak to the suprathermal tail. We conclude from our study that the solar wind is the most significant source of the high-energy ions for this event. Our results have important implications for the physics of the so-called `injection problem', which will be discussed.

Study of high energy ion implantation of boron and oxygen in silicon

International Nuclear Information System (INIS)

Thevenin, P.

1991-06-01

Three aspects of high energy (0.5-3 MeV) light ions ( 11 B + and 16 O + ) implantation in silicon are examined: (1)Spatial repartition; (2) Target damage and (3) Synthesis by oxygen implantation of a buried silicon oxide layer

The Effect of Solar Wind Variations on the Escape of Oxygen Ions From Mars Through Different Channels: MAVEN Observations

Science.gov (United States)

Dubinin, E.; Fraenz, M.; Pätzold, M.; McFadden, J.; Halekas, J. S.; DiBraccio, G. A.; Connerney, J. E. P.; Eparvier, F.; Brain, D.; Jakosky, B. M.; Vaisberg, O.; Zelenyi, L.

2017-11-01

We present multi-instrument observations of the effects of solar wind on ion escape fluxes on Mars based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) data from 1 November 2014 to 15 May 2016. Losses of oxygen ions through different channels (plasma sheet, magnetic lobes, boundary layer, and ion plume) as a function of the solar wind and the interplanetary magnetic field variations were studied. We have utilized the modified Mars Solar Electric (MSE) coordinate system for separation of the different escape routes. Fluxes of the low-energy (≤30 eV) and high-energy (≥30 eV) ions reveal different trends with changes in the solar wind dynamic pressure, the solar wind flux, and the motional electric field. Major oxygen fluxes occur through the tail of the induced magnetosphere. The solar wind motional electric field produces an asymmetry in the ion fluxes and leads to different relations between ion fluxes supplying the tail from the different hemispheres and the solar wind dynamic pressure (or flux) and the motional electric field. The main driver for escape of the high-energy oxygen ions is the solar wind flux (or dynamic pressure). On the other hand, the low-energy ion component shows the opposite trend: ion flux decreases with increasing solar wind flux. As a result, the averaged total oxygen ion fluxes reveal a low variability with the solar wind strength. The large standard deviations from the averages values of the escape fluxes indicate the existence of mechanisms which can enhance or suppress the efficiency of the ion escape. It is shown that the Martian magnetosphere possesses the properties of a combined magnetosphere which contains different classes of field lines. The existence of the closed magnetic field lines in the near-Mars tail might be responsible for suppression of the ion escape fluxes.

A comparative study of 30MeV boron4+ and 60MeV oxygen8+ ion irradiated Si NPN BJTs

International Nuclear Information System (INIS)

Kumar, M. Vinay; Krishnaveni, S.; Yashoda, T.; Dinesh, C. M.; Krishnakumar, K. S.; Jayashree, B.; Ramani

2015-01-01

The impact of 30MeV boron 4+ and 60MeV oxygen 8+ ion irradiation on electrical characteristics of 2N3773 Si NPN Bipolar junction transistors (BJTs) is reported in the present study. The transistors were decapped and irradiated at room temperature. Gummel characteristics, DC current gain and Capacitance-voltage (C-V) characteristics were studied before and after irradiation at different fluences. DC current gain has decreased significantly in both boron and oxygen ion irradiation. Also the value of capacitance decreased 3-4 times with increase in fluence. Both 30MeV boron ion and 60MeV oxygen ion induced similar extent of degradation in electrical characteristics of the transistor

Simulation of electromagnetic ion cyclotron triggered emissions in the Earth's inner magnetosphere

Science.gov (United States)

Shoji, Masafumi; Omura, Yoshiharu

2011-05-01

In a recent observation by the Cluster spacecraft, emissions triggered by electromagnetic ion cyclotron (EMIC) waves were discovered in the inner magnetosphere. We perform hybrid simulations to reproduce the EMIC triggered emissions. We develop a self-consistent one-dimensional hybrid code with a cylindrical geometry of the background magnetic field. We assume a parabolic magnetic field to model the dipole magnetic field in the equatorial region of the inner magnetosphere. Triggering EMIC waves are driven by a left-handed polarized external current assumed at the magnetic equator in the simulation model. Cold proton, helium, and oxygen ions, which form branches of the dispersion relation of the EMIC waves, are uniformly distributed in the simulation space. Energetic protons with a loss cone distribution function are also assumed as resonant particles. We reproduce rising tone emissions in the simulation space, finding a good agreement with the nonlinear wave growth theory. In the energetic proton velocity distribution we find formation of a proton hole, which is assumed in the nonlinear wave growth theory. A substantial amount of the energetic protons are scattered into the loss cone, while some of the resonant protons are accelerated to higher pitch angles, forming a pancake velocity distribution.

Proton Transfer Time-of-Flight Mass Spectrometer

Energy Technology Data Exchange (ETDEWEB)

Watson, Thomas B. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2016-03-01

The Proton Transfer Reaction Mass Spectrometer (PTRMS) measures gas-phase compounds in ambient air and headspace samples before using chemical ionization to produce positively charged molecules, which are detected with a time-of-flight (TOF) mass spectrometer. This ionization method uses a gentle proton transfer reaction method between the molecule of interest and protonated water, or hydronium ion (H₃O⁺), to produce limited fragmentation of the parent molecule. The ions produced are primarily positively charged with the mass of the parent ion, plus an additional proton. Ion concentration is determined by adding the number of ions counted at the molecular ion’s mass-to-charge ratio to the number of air molecules in the reaction chamber, which can be identified according to the pressure levels in the reaction chamber. The PTRMS allows many volatile organic compounds in ambient air to be detected at levels from 10–100 parts per trillion by volume (pptv). The response time is 1 to 10 seconds.

The study of PDMS surface treatment and it's applications by using proton beam

International Nuclear Information System (INIS)

Baek, J. Y.; Kim, J. Y.; Kwon, K. H.; Park, J. Y.

2007-04-01

PDMS(Polydimethylsiloxane) is mainly used as a material to do lab on a chip for biochemical analysis. PDMS has many applicability at the Bio-Technology(BT) field, because it is flexible, biocompatible and has good oxygen permeability. In this study, we have investigated to physical and chemical changes of PDMS surface by proton beam radiation conditions. The used kind of ion were Ar and N, beam energy was 30keV, 60keV, 80keV, total fluence was 1E10 to 1E16 [ions/cm 2 ]. PDMS membrane was produced as 150 μm thick on the 3' silicon wafer. We inquired into physical and chemical changes up to beam radiation conditions through the investigate the change of surface roughness by AFM(Atomic Force Microscope), the change of surface morphology by SEM(Scanning Electron Microscope) and the change of chemical composition by FT-IR(Fourier Transform Infrared Raman spectroscopy) and XPS(X-ray Photoelectron Spectroscopy). From these basic data to we set up the proton beam radiation conditions to secure metal layer and PDMS adhesion. This enables to produce the electrode at the PDMS material lab on a chip. From now on, we'll investigate the cell patterning possibility after carry out of cell culture with mouse fibroblast at PDMS surface what is surface modification by using of proton beam radiation and apply this to produce lab on a chip. Physical property: Surface roughness of PDMS membrane was observed using AFM, after exposure of proton beam on it. The roughness increased as the power level of proton beam increase. This phenomena was caused by the kinetic energy of particle. Chemical property: Long term observation was conducted on the contact angles of the samples made by the proton beam exposure or oxygen plasma treatment; the hydrophilicity was found to be stronger in the samples made by the proton beam exposure. We found the reason of this was the destruction of polymer chains by proton beam. Feasibility of Through-hole: Considering that comparatively high level energy beam

Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

Directory of Open Access Journals (Sweden)

Emiliana Fabbri, Daniele Pergolesi and Enrico Traversa

2010-01-01

Full Text Available High temperature proton conductor (HTPC oxides are attracting extensive attention as electrolyte materials alternative to oxygen-ion conductors for use in solid oxide fuel cells (SOFCs operating at intermediate temperatures (400–700 °C. The need to lower the operating temperature is dictated by cost reduction for SOFC pervasive use. The major stake for the deployment of this technology is the availability of electrodes able to limit polarization losses at the reduced operation temperature. This review aims to comprehensively describe the state-of-the-art anode and cathode materials that have so far been tested with HTPC oxide electrolytes, offering guidelines and possible strategies to speed up the development of protonic SOFCs.

Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

International Nuclear Information System (INIS)

Fabbri, Emiliana; Pergolesi, Daniele; Traversa, Enrico

2010-01-01

High temperature proton conductor (HTPC) oxides are attracting extensive attention as electrolyte materials alternative to oxygen-ion conductors for use in solid oxide fuel cells (SOFCs) operating at intermediate temperatures (400-700 0 C). The need to lower the operating temperature is dictated by cost reduction for SOFC pervasive use. The major stake for the deployment of this technology is the availability of electrodes able to limit polarization losses at the reduced operation temperature. This review aims to comprehensively describe the state-of-the-art anode and cathode materials that have so far been tested with HTPC oxide electrolytes, offering guidelines and possible strategies to speed up the development of protonic SOFCs. (topical review)

Molecular hydrogen messengers can lead to structural infidelity: A cautionary tale of protonated glycine

Energy Technology Data Exchange (ETDEWEB)

Masson, Antoine, E-mail: amasson@lbl.gov; Rizzo, Thomas R., E-mail: erw@berkeley.edu, E-mail: thomas.rizzo@epfl.ch [Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne (Switzerland); Williams, Evan R., E-mail: erw@berkeley.edu, E-mail: thomas.rizzo@epfl.ch [Department of Chemistry, University of California, Berkeley, California 94720-1460 (United States)

2015-09-14

The effects of tagging protonated glycine with either He or between 1 and 14 H{sub 2} molecules on the infrared photodissociation spectra and the ion structure were investigated. Differences in the IR spectra with either a single He atom or H{sub 2} molecule attached indicate that even a single H{sub 2} molecule can affect the frequencies of some vibrational bands of this simple ion. The protonation site is the preferred location of the tag with He and with up to two H{sub 2} molecules, but evidence for H{sub 2} attachment to the hydrogen atom of the uncharged carboxylic acid is observed for ions tagged with three or more H{sub 2} molecules. This results in a 55 cm{sup −1} red shift in the carboxylic acid OH stretch, and evidence for some structural isomers where the hydrogen bond between the protonated nitrogen and the carbonyl oxygen is partially broken; as a result H{sub 2} molecules attached to this site are observed. These results are supported by theory, which indicates that H{sub 2} molecules can effectively break this weak hydrogen bond with three or more H{sub 2} molecules. These results indicate that large spectral shifts as a result of H{sub 2} molecules attaching to sites remote from the charge can occur and affect stretching frequencies as a result of charge transfer, and that tagging with multiple H{sub 2} molecules can change the structure of the ion itself.

Energy deposition and ion production from thermal oxygen ion precipitation during Cassini's T57 flyby

Science.gov (United States)

Snowden, Darci; Smith, Michael; Jimson, Theodore; Higgins, Alex

2018-05-01

Cassini's Radio Science Investigation (RSS) and Langmuir Probe observed abnormally high electron densities in Titan's ionosphere during Cassini's T57 flyby. We have developed a three-dimensional model to investigate how the precipitation of thermal magnetospheric O+ may have contributed to enhanced ion production in Titan's ionosphere. The three-dimensional model builds on previous work because it calculates both the flux of oxygen through Titan's exobase and the energy deposition and ion production rates in Titan's atmosphere. We find that energy deposition rates and ion production rates due to thermal O+ precipitation have a similar magnitude to the rates from magnetospheric electron precipitation and that the simulated ionization rates are sufficient to explain the abnormally high electron densities observed by RSS and Cassini's Langmuir Probe. Globally, thermal O+ deposits less energy in Titan's atmosphere than solar EUV, suggesting it has a smaller impact on the thermal structure of Titan's neutral atmosphere. However, our results indicate that thermal O+ precipitation can have a significant impact on Titan's ionosphere.

Apparatus for proton radiography

International Nuclear Information System (INIS)

Martin, R.L.

1976-01-01

An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors. 10 claims, 7 drawing figures

Developments in the design of proton and ion accelerators for medical use

CERN Document Server

Bryant, P J

1998-01-01

Accelerators and medicine have been close companions since cyclotrons first made biological studies with particle beams possible in the 1930s. Later improvements, such as H-minus (H-) extraction, made cyclotrons the foremost, commercially-available producer of medical isotopes. Although the world's first hospital-based proton treatment centre, Loma Linda, uses a synchrotron, the cyclotron is now al so establishing a dominance in proton centres using passive beam spreading. However, two trends indicate a slightly different direction. The first is towards light ions and the second is towards 'penc il' beam scanning with active energy control. Together, these point to a new generation of synchrotrons with slow-beam-extraction systems that allow time for on-line dosimetry and provide very smooth spills. There are several variants for the slow extraction including the use of a betatron core and rf knockout. There are also methods for improving the spill quality such as rf channelling buckets a nd rf noise. The use...

Fragment formation in GeV-energy proton and light heavy-ion induced reactions

International Nuclear Information System (INIS)

Murakami, T.; Haga, M.; Haseno, M.

2002-01-01

We have investigated similarities and differences among the fragment formation processes in GeV-energy light-ion and light heavy-ion induced reactions. We have newly measured inclusive and exclusive energy spectra of intermediate mass fragments (3 ≤ Z ≤ 30; IMFs) for 8-GeV 16 O and 20 Ne and 12-GeV 20 Ne induced target multifragmentations (TMFs) in order to compare them with those previously measured for 8- and 12-GeV proton induced TMFs. We fond noticeable difference in their spectrum shapes and magnitudes but all of them clearly indicate the existence of sideward-peaked components, indicating fragment formations are mainly dictated not by a incident energy per nucleon but by a total energy of the projectile. (author)

Beam pinging, sweeping, shaking, and electron/ion collecting, at the Proton Storage Ring

International Nuclear Information System (INIS)

Hardek, T.W.; Macek, R.J.; Plum, M.A.; Wang, T.S.F.

1993-01-01

We have built, installed and tested a pinger for use as a general diagnostic at the Los Alamos Proton Storage Ring (PSR). Two 4-m-long parallel-plate electrodes with a plate spacing of 10.2 cm provide kicks of up to 1.1 mrad. A pair of solid-state pulsers may be operated in a single-pulse mode for beam pinging (tune measurements) or in a burst mode at up to 700 kHz pulse rates for beam sweeping. During our 1992 operating period we used the pinger for beam sweeping, for beam shaking, for measuring the tune shift, and we have used it as an ion chamber. Using the pinger as an ion chamber during production conditions has yielded some surprising results

Simulations of Proton Implantation in Silicon Carbide (SiC)

Science.gov (United States)

2016-03-31

Simulations of Proton Implantation in Silicon Carbide (SiC) Jonathan P. McCandless, Hailong Chen, Philip X.-L. Feng Electrical Engineering, Case...of implanting protons (hydrogen ions, H+) into SiC thin layers on silicon (Si) substrate, and explore the ion implantation conditions that are...relevant to experimental radiation of SiC layers. Keywords: silicon carbide (SiC); radiation effects; ion implantation ; proton; stopping and range of

Brain Injury After Proton Therapy or Carbon Ion Therapy for Head-and-Neck Cancer and Skull Base Tumors

International Nuclear Information System (INIS)

Miyawaki, Daisuke; Murakami, Masao; Demizu, Yusuke; Sasaki, Ryohei; Niwa, Yasue; Terashima, Kazuki; Nishimura, Hideki; Hishikawa, Yoshio; Sugimura, Kazuro

2009-01-01

Purpose: To assess the incidence of early delayed or late morbidity of Brain after particle therapy for skull base tumors and head-and-neck cancers. Methods and Materials: Between May 2001 and December 2005, 59 patients with cancerous invasion of the skull base were treated with proton or carbon ion therapy at the Hyogo Ion Beam Medical Center. Adverse events were assessed according to the magnetic resonance imaging findings (late effects of normal tissue-subjective, objective, management, analytic [LENT-SOMA]) and symptoms (Common Terminology Criteria for Adverse Events [CTCAE], version 3.0). Dose-volume histograms were used to analyze the relationship between the dose and volume of the irradiated brain and the occurrence of brain injury. The median follow-up time was 33 months. Results: Of the 48 patients treated with proton therapy and 11 patients treated with carbon ion radiotherapy, 8 (17%) and 7 (64%), respectively, developed radiation-induced brain changes (RIBCs) on magnetic resonance imaging (LENT-SOMA Grade 1-3). Four patients (7%) had some clinical symptoms, such as vertigo and headache (CTCAE Grade 2) or epilepsy (CTCAE Grade 3). The actuarial occurrence rate of RIBCs at 2 and 3 years was 20% and 39%, respectively, with a significant difference in the incidence between the proton and carbon ion radiotherapy groups. The dose-volume histogram analyses revealed significant differences between Brain lobes with and without RIBCs in the actuarial volume of brain lobes receiving high doses. Conclusion: Particle therapies produced minimal symptomatic brain toxicities, but sequential evaluation with magnetic resonance imaging detected a greater incidence of RIBCs. Significant differences were observed in the irradiated brain volume between Brain lobes with and without RIBCs.

Development of superconducting crossbar-H-mode cavities for proton and ion accelerators

Directory of Open Access Journals (Sweden)

F. Dziuba

2010-04-01

Full Text Available The crossbar-H-mode (CH structure is the first superconducting multicell drift tube cavity for the low and medium energy range operated in the H_{21} mode. Because of the large energy gain per cavity, which leads to high real estate gradients, it is an excellent candidate for the efficient acceleration in high power proton and ion accelerators with fixed velocity profile. A prototype cavity has been developed and tested successfully with a gradient of 7  MV/m. A few new superconducting CH cavities with improved geometries for different high power applications are under development at present. One cavity (f=325  MHz, β=0.16, seven cells is currently under construction and studied with respect to a possible upgrade option for the GSI UNILAC. Another cavity (f=217  MHz, β=0.059, 15 cells is designed for a cw operated energy variable heavy ion linac application. Furthermore, the EUROTRANS project (European research program for the transmutation of high level nuclear waste in an accelerator driven system, 600 MeV protons, 352 MHz is one of many possible applications for this kind of superconducting rf cavity. In this context a layout of the 17 MeV EUROTRANS injector containing four superconducting CH cavities was proposed by the Institute for Applied Physics (IAP Frankfurt. The status of the cavity development related to the EUROTRANS injector is presented.

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

International Nuclear Information System (INIS)

Zhao, H.; University of Colorado, Boulder, CO; Li, X.; University of Colorado, Boulder, CO; Baker, D. N.

2015-01-01

Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O + . This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.

Batch test equilibration studies examining the removal of Cs, Sr, and Tc from supernatants from ORNL underground storage tanks by selected ion exchangers

International Nuclear Information System (INIS)

Collins, J.L.; Egan, B.Z.; Anderson, K.K.; Chase, C.W.; Bell, J.T.

1995-01-01

Bench-scale batch equilibration tests have been conducted with supernatants from two underground tanks at the Melton Valley Storage Tank (MVST) Facility at Oak Ridge National Laboratory (ORNL) to determine the effectiveness of selected ion exchangers in removing cesium, strontium, and technetium. Seven sorbents were evaluated for cesium removal, nine for strontium removal, and four for technetium removal. The results indicate that granular potassium cobalt hexacyanoferrate was the most effective of the exchangers evaluated for removing cesium from the supernatants. The powdered forms of sodium titanate (NaTiO) and cystalline silicotitanate (CST) were superior in removing the strontium; however, for the sorbents of suitable particle size for column use, titanium monohydrogen phosphate (TiHP φ), sodium titanate/polyacrylonitrile (NaTiO-PAN), and titanium monohydrogen phosphate/polyacrylonitrile (TiP-PAN) gave the best results and were about equally effective. Reillex trademark 402 was the most effective exchanger in removing the technetium; however, it was only slightly more satisfactory than Reillex trademark HPQ

Molecular simulations of hydrated proton exchange membranes. The structure

Energy Technology Data Exchange (ETDEWEB)

Marcharnd, Gabriel [Duisburg-Essen Univ., Essen (Germany). Lehrstuhl fuer Theoretische Chemie; Bordeaux Univ., Talence (France). Dept. of Chemistry; Bopp, Philippe A. [Bordeaux Univ., Talence (France). Dept. of Chemistry; Spohr, Eckhard [Duisburg-Essen Univ., Essen (Germany). Lehrstuhl fuer Theoretische Chemie

2013-01-15

The structure of two hydrated proton exchange membranes for fuel cells (PEMFC), Nafion {sup registered} (Dupont) and Hyflon {sup registered} (Solvay), is studied by all-atom molecular dynamics (MD) computer simulations. Since the characteristic times of these systems are long compared to the times for which they can be simulated, several different, but equivalent, initial configurations with a large degree of randomness are generated for different water contents and then equilibrated and simulated in parallel. A more constrained structure, analog to the newest model proposed in the literature based on scattering experiments, is investigated in the same way. One might speculate that a limited degree of entanglement of the polymer chains is a key feature of the structures showing the best agreement with experiment. Nevertheless, the overall conclusion remains that the scattering experiments cannot distinguish between the several, in our view equally plausible, structural models. We thus find that the characteristic features of experimental scattering curves are, after equilibration, fairly well reproduced by all systems prepared with our method. We thus study in more detail some structural details. We attempt to characterize the spatial and size distribution of the water rich domains, which is where the proton diffusion mostly takes place, using several clustering algorithms. (orig.)

Effects of oxygen gas flow rate and ion beam plasma conditions on the opto-electronic properties of indium molybdenum oxide films fabricated by ion beam-assisted evaporation

International Nuclear Information System (INIS)

Kuo, C.C.; Liu, C.C.; Lin, C.C.; Liou, Y.Y.; He, J.L.; Chen, F.S.

2008-01-01

The purpose of the present work is to experimentally study the effects of the oxygen gas flow rate and ion beam plasma conditions on the properties of indium molybdenum oxide (IMO) films deposited onto the polyethersulfone (PES) substrate. Crystal structure, surface morphology, and optoelectronic properties of IMO films are examined as a function of oxygen gas flow rate and ion beam discharge voltage. Experimental results show that the IMO films consist of a cubic bixbyite B-In 2 O 3 single phase with its crystal preferred orientation alone B(222). Mo 6+ ions are therefore considered to partially substitute In 3+ sites in the deposit. Under-controlled ion bombardment during deposition enhances the reaction among those arriving oxygen and metal ion species to condense into IMO film and facilitates a decreased surface roughness of IMO film. The film with ultimate crystallinity and the lowest surface roughness is obtained when the oxygen flow rate of 3 sccm and the discharge voltage of 110 V are employed. This results in the lowest electrical resistivity due mainly to the increased Hall mobility and irrelevant to carrier concentration. The lowest electrical resistivity of 8.63 x 10 -4 ohm-cm with a 84.63% transmittance at a wavelength of 550 nm can be obtained, which satisfies the requirement of a flexible transparent conductive polymer substrate

Study of silicon doped with zinc ions and annealed in oxygen

International Nuclear Information System (INIS)

Privezentsev, V. V.; Kirilenko, E. P.; Goryachev, A. N.; Batrakov, A. A.

2017-01-01

The results of studies of the surface layer of silicon and the formation of precipitates in Czochralski n-Si (100) samples implanted with "6"4Zn"+ ions with an energy of 50 keV and a dose of 5 × 10"1"6 cm"–"2 at room temperature and then oxidized at temperatures from 400 to 900°C are reported. The surface is visualized using an electron microscope, while visualization of the surface layer is conducted via profiling in depth by elemental mapping using Auger electron spectroscopy. The distribution of impurity ions in silicon is analyzed using a time-of-flight secondary-ion mass spectrometer. Using X-ray photoelectron spectroscopy, the chemical state of atoms of the silicon matrix and zinc and oxygen impurity atoms is studied, and the phase composition of the implanted and annealed samples is refined. After the implantation of zinc, two maxima of the zinc concentration, one at the wafer surface and the other at a depth of 70 nm, are observed. In this case, nanoparticles of the Zn metal phase and ZnO phase, about 10 nm in dimensions, are formed at the surface and in the surface layer. After annealing in oxygen, the ZnO · Zn_2SiO_4 and Zn · ZnO phases are detected near the surface and at a depth of 50 nm, respectively.

On the Experimental Investigation of the Clamping Pressure Effects on the Proton Exchange Membrane Water Electrolyser Cell Performance

DEFF Research Database (Denmark)

Al Shakhshir, Saher; Frensch, Steffen Henrik; Kær, Søren Knudsen

2017-01-01

energy sources. The proton exchange membrane water electrolyser(PEMWE) is the most candidate technology to produce hydrogen from renewable energysources. PEMWE cell splits water into hydrogen and oxygen when an electric current is passedthrough it. Electrical current forces the positively charged ions...... to migrate to negatively chargedcathode, where hydrogen is reduced. Meanwhile, oxygen is produced at the anode sideelectrode and escape as a gas with the circulating water. In the recent few years, PEMWE’s R&D has inched towards; operating conditions; such asincreased operating temperature and cathode...

Formation of oxides and segregation of mobile atoms during SIMS profiling of Si with oxygen ions

Energy Technology Data Exchange (ETDEWEB)

Petravic, M.; Williams, J.S.; Svensson, B.G.; Conway, M. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

1993-12-31

An oxygen beam is commonly used in secondary ion mass spectroscopy (SIMS) analysis to enhance the ionization probability for positive secondary ions. It has been observed, however, that this technique produces in some cases a great degradation of depth resolution. The most pronounced effects have been found for impurities in silicon under oxygen bombardment at angles of incidence smaller than {approx} 30 deg from the surface normal. A new approach is described which involved broadening of SIMS profiles for some mobile atoms, such as Cu, Ni and Au, implanted into silicon. The anomalously large broadening is explained in terms of segregation at a SiO{sub 2}/Si interface formed during bombardment with oxygen at impact angles less than 30 deg. 2 refs., 1 tab., 4 figs.

Formation of oxides and segregation of mobile atoms during SIMS profiling of Si with oxygen ions

Energy Technology Data Exchange (ETDEWEB)

Petravic, M; Williams, J S; Svensson, B G; Conway, M [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

1994-12-31

An oxygen beam is commonly used in secondary ion mass spectroscopy (SIMS) analysis to enhance the ionization probability for positive secondary ions. It has been observed, however, that this technique produces in some cases a great degradation of depth resolution. The most pronounced effects have been found for impurities in silicon under oxygen bombardment at angles of incidence smaller than {approx} 30 deg from the surface normal. A new approach is described which involved broadening of SIMS profiles for some mobile atoms, such as Cu, Ni and Au, implanted into silicon. The anomalously large broadening is explained in terms of segregation at a SiO{sub 2}/Si interface formed during bombardment with oxygen at impact angles less than 30 deg. 2 refs., 1 tab., 4 figs.

BIANCA, a biophysical model of cell survival and chromosome damage by protons, C-ions and He-ions at energies and doses used in hadrontherapy

Science.gov (United States)

Pietro Carante, Mario; Aimè, Chiara; Tello Cajiao, John James; Ballarini, Francesca

2018-04-01

An upgraded version of the BIANCA II biophysical model, which describes more realistically interphase chromosome organization and the link between chromosome aberrations and cell death, was applied to V79 and AG01522 cells exposed to protons, C-ions and He-ions over a wide LET interval (0.6–502 keV µm‑1), as well as proton-irradiated U87 cells. The model assumes that (i) ionizing radiation induces DNA ‘cluster lesions’ (CLs), where by definition each CL produces two independent chromosome fragments; (ii) fragment (distance-dependent) mis-rejoining, or un-rejoining, produces chromosome aberrations; (iii) some aberrations lead to cell death. The CL yield, which mainly depends on radiation quality but is also modulated by the target cell, is an adjustable parameter. The fragment un-rejoining probability, f, is the second, and last, parameter. The value of f, which is assumed to depend on the cell type but not on radiation quality, was taken from previous studies, and only the CL yield was adjusted in the present work. Good agreement between simulations and experimental data was obtained, suggesting that BIANCA II is suitable for calculating the biological effectiveness of hadrontherapy beams. For both V79 and AG01522 cells, the mean number of CLs per micrometer was found to increase with LET in a linear-quadratic fashion before the over-killing region, where a less rapid increase, with a tendency to saturation, was observed. Although the over-killing region deserves further investigation, the possibility of fitting the CL yields is an important feature for hadrontherapy, because it allows performing predictions also at LET values where experimental data are not available. Finally, an approach was proposed to predict the ion-response of the cell line(s) of interest from the ion-response of a reference cell line and the photon response of both. A pilot study on proton-irradiated AG01522 and U87 cells, taking V79 cells as a reference, showed encouraging

Growth and Properties of Oxygen and Ion Doped BISMUTH(2) STRONTIUM(2) Calcium COPPER(2) Oxygen (8+DELTA) Single Crystals

Science.gov (United States)

Mitzi, David Brian

1990-01-01

A directional solidification method for growing large single crystals in the Bi_2Sr _2CaCu_2O _{8+delta} system is reported. Ion substitutions, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Ion doping results in little change of the superconducting transition for substitution levels below 20-25% (as a result of simultaneous oxygen intercalation), while beyond this level, the Meissner signal broadens and the low temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals, provides evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed) while the Hall concentrations increase from n = 3.1(3) times 10 ^{21} cm^{ -3} (0.34 holes/Cu site) to 4.6(3) times 10^{21} cm^{-3} (0.50 holes/Cu site). Further suppression of T_{c} to 72K is possible by annealing in oxygen pressures up to 100atm. No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen doped Bi_2Sr _2CaCu_2O _{8+delta} is a suitable system for pursuing doping studies. The decrease in T _{c} with concentration for 0.34 <=q n <=q 0.50 indicates that a high carrier concentration regime exists where T_{c} decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. The physical properties of these Bi _2Sr_2CaCu _2O_{8+delta} crystals, in this high carrier concentration regime, will be discussed.

Semiconductors Under Ion Radiation: Ultrafast Electron-Ion Dynamics in Perfect Crystals and the Effect of Defects

Science.gov (United States)

Lee, Cheng-Wei; Schleife, André

Stability and safety issues have been challenging difficulties for materials and devices under radiation such as solar panels in outer space. On the other hand, radiation can be utilized to modify materials and increase their performance via focused-ion beam patterning at nano-scale. In order to grasp the underlying processes, further understanding of the radiation-material and radiation-defect interactions is required and inevitably involves the electron-ion dynamics that was traditionally hard to capture. By applying Ehrenfest dynamics based on time-dependent density functional theory, we have been able to perform real-time simulation of electron-ion dynamics in MgO and InP/GaP. By simulating a high-energy proton penetrating the material, the energy gain of electronic system can be interpreted as electronic stopping power and the result is compared to existing data. We also study electronic stopping in the vicinity of defects: for both oxygen vacancy in MgO and interface of InP/GaP superlattice, electronic stopping shows strong dependence on the velocity of the proton. To study the energy transfer from electronic system to lattice, simulations of about 100 femto-seconds are performed and we analyze the difference between Ehrenfest and Born-Oppenheimer molecular dynamics.

FY 1998 annual report on the development of novel, high-activity oxygen electrode by ion-implantation; 1998 nendo ion chunyuho ni yoru shinkina kokassei sanso denkyoku no kaihatsu chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

An attempt has been made to develop an electrode material having high activity for oxygen generating reactions by ion-implantation, which is used to form the bulk defects (fine gaps at the atomic level) on the electrode surface, considered to serve as the active sites. It is found that implantation of the Co{sup +} or Zn{sup +} ion into a compound oxide electrode of Ti and Ru is accompanied by decreased overvoltage for oxygen generation by 50 to 100 mV. The Co{sup +} and Zn{sup +} ions, when implanted, cause damage of similar density in the thin film, decreasing its overvoltage to a similar extent, in spite of their different chemical properties, from which it is considered that the effect of ion implantation is not to change chemical properties of the film but to form a structural defect therein. A thin-film electrode of ruthenium dioxide, which is considered to be the oxygen generating electrode of the highest activity at present, is prepared and implanted with the Ru{sup +} ion, to observe the effect. The ion implantation also decreases the overvoltage by 50 to 70 mV, demonstrating its effect. The same principle is expected to be applicable to development of high-activity oxygen reducing electrode (electrode for fuel cell). (NEDO)

STARCODES, Stopping Power and Ranges for Electrons, Protons, He

International Nuclear Information System (INIS)

2000-01-01

1 - Description of program or function: The 'STAR CODES', ESTAR, PSTAR, and ASTAR, calculate stopping-power and range tables for electrons, protons, and helium ions (alphas), according to methods described in ICRU Reports 37 and 39. 2 - Method of solution: Collision stopping powers are calculated from the theory of Bethe (1930, 1932), with a density-effect correction evaluated according to Sternheimer (1952, 1982). The stopping-power formula contains an important parameter, the mean excitation energy (I-value), which characterizes the stopping properties of a material. The codes provide output for electrons in any stopping material (279 provided) and for protons and helium ions in 74 materials. The calculations include the 1) Collision stopping power, 2) Radiative stopping power (electrons only), 3) Nuclear stopping power (protons and helium ions), 4) Total stopping power, 5) CSDA range, 6) Projected range (protons and helium ions), 7) Density effect parameter (electrons), 8) Radiation yield (electrons), and 9) Detour factor (protons and helium ions). Standard energy grids and files of elements w/ionization-excitation information are included with lookup table capabilities. 3 - Restrictions on the complexity of the problem: The minimum energies used in the calculations are at 1 KeV (protons and helium ions) and 10 KeV (electrons), and the maximum are 1 GeV. The standard energy grids are set at 81 for electrons, equally spaced (logarithmically), 133 for protons, and 122 for helium ions. The lower energy electron calculations (< 10 KeV) have up to 5-10% errors and are considered too fallable

Proton and carbon ion radiotherapy for primary brain tumors and tumors of the skull base

Energy Technology Data Exchange (ETDEWEB)

Combs, Stephanie E.; Kessel, Kerstin; Habermehl, Daniel; Debus, Jurgen [Univ. Hospital of Heidelberg, Dept. of Radiation Oncology, Heidelberg (Germany)], e-mail: Stephanie.Combs@med.uni-heidelberg.de; Haberer, Thomas [Heidelberger Ionenstrahl Therapiezentrum (HIT), Heidelberg (Germany); Jaekel, Oliver [Univ. Hospital of Heidelberg, Dept. of Radiation Oncology, Heidelberg (Germany); Heidelberger Ionenstrahl Therapiezentrum (HIT), Heidelberg (Germany)

2013-10-15

To analyze clinical concepts, toxicity and treatment outcome in patients with brain and skull base tumors treated with photons and particle therapy. Material and methods: In total 260 patients with brain tumors and tumors of the skull base were treated at the Heidelberg Ion Therapy Center (HIT). Patients enrolled in and randomized within prospective clinical trials as well as bony or soft tissue tumors are not included in this analysis. Treatment was delivered as protons, carbon ions, or combinations of photons and a carbon ion boost. All patients are included in a tight follow-up program. The median follow-up time is 12 months (range 2-39 months). Results: Main histologies included meningioma (n = 107) for skull base lesions, pituitary adenomas (n = 14), low-grade gliomas (n = 51) as well as high-grade gliomas (n = 55) for brain tumors. In all patients treatment could be completed without any unexpected severe toxicities. No side effects > CTC Grade III were observed. To date, no severe late toxicities were observed, however, for endpoints such as secondary malignancies or neuro cognitive side effects follow-up time still remains too short. Local recurrences were mainly seen in the group of high-grade gliomas or atypical meningiomas; for benign skull base meningiomas, to date, no recurrences were observed during follow-up. Conclusion: The specific benefit of particle therapy will potentially reduce the risk of secondary malignancies as well as improve neuro cognitive outcome and quality of life (QOL); thus, longer follow-up will be necessary to confirm these endpoints. Indication-specific trials on meningiomas and gliomas are underway to elucidate the role of protons and carbon ions in these indications.

Proton and carbon ion radiotherapy for primary brain tumors and tumors of the skull base

International Nuclear Information System (INIS)

Combs, Stephanie E.; Kessel, Kerstin; Habermehl, Daniel; Debus, Jurgen; Haberer, Thomas; Jaekel, Oliver

2013-01-01

To analyze clinical concepts, toxicity and treatment outcome in patients with brain and skull base tumors treated with photons and particle therapy. Material and methods: In total 260 patients with brain tumors and tumors of the skull base were treated at the Heidelberg Ion Therapy Center (HIT). Patients enrolled in and randomized within prospective clinical trials as well as bony or soft tissue tumors are not included in this analysis. Treatment was delivered as protons, carbon ions, or combinations of photons and a carbon ion boost. All patients are included in a tight follow-up program. The median follow-up time is 12 months (range 2-39 months). Results: Main histologies included meningioma (n = 107) for skull base lesions, pituitary adenomas (n = 14), low-grade gliomas (n = 51) as well as high-grade gliomas (n = 55) for brain tumors. In all patients treatment could be completed without any unexpected severe toxicities. No side effects > CTC Grade III were observed. To date, no severe late toxicities were observed, however, for endpoints such as secondary malignancies or neuro cognitive side effects follow-up time still remains too short. Local recurrences were mainly seen in the group of high-grade gliomas or atypical meningiomas; for benign skull base meningiomas, to date, no recurrences were observed during follow-up. Conclusion: The specific benefit of particle therapy will potentially reduce the risk of secondary malignancies as well as improve neuro cognitive outcome and quality of life (QOL); thus, longer follow-up will be necessary to confirm these endpoints. Indication-specific trials on meningiomas and gliomas are underway to elucidate the role of protons and carbon ions in these indications

Proton diffraction

International Nuclear Information System (INIS)

Den Besten, J.L.; Jamieson, D.N.; Allen, L.J.

1998-01-01

The Lindhard theory on ion channeling in crystals has been widely accepted throughout ion beam analysis for use in simulating such experiments. The simulations use a Monte Carlo method developed by Barret, which utilises the classical 'billiard ball' theory of ions 'bouncing' between planes or tubes of atoms in the crystal. This theory is not valid for 'thin' crystals where the planes or strings of atoms can no longer be assumed to be of infinite proportions. We propose that a theory similar to that used for high energy electron diffraction can be applied to MeV ions, especially protons, in thin crystals to simulate the intensities of transmission channeling and of RBS spectra. The diffraction theory is based on a Bloch wave solution of the Schroedinger equation for an ion passing through the periodic crystal potential. The widely used universal potential for proton-nucleus scattering is used to construct the crystal potential. Absorption due to thermal diffuse scattering is included. Experimental parameters such as convergence angle, beam tilt and scanning directions are considered in our calculations. Comparison between theory and experiment is encouraging and suggests that further work is justified. (authors)

Equilibration of matter near the QCD critical point

International Nuclear Information System (INIS)

Bravina, L V; Arsene, I; Nilsson, M S; Tywoniuk, K; Zabrodin, E E

2006-01-01

The relaxation of hot and dense nuclear matter to local equilibrium in the central zone of heavy-ion collisions at energies around 40 A GeV is studied within the microscopic transport model. Dynamical calculations performed for the central cell in the reaction are compared to the predictions of the thermal statistical model. It is found that kinetic, thermal and chemical equilibrations of the expanding hadronic matter are nearly approached for the period of 10-18 fm/c. Within this time, the matter in the cell expands almost isentropically. It is quite interesting that in the T-μ B plane the system crosses the critical point predicted by lattice QCD calculations. Similar to the cells studied at lower (AGS) and higher (SPS, RHIC) energies, the central cell at 40 A GeV possesses negative (though small) net strangeness. Several peculiarities are observed as well. These features can be attributed to the transition from baryon-dominated to meson-dominated matter, discussed recently

Energy dependent track structure parametrizations for protons and carbon ions based on nano-metric simulations

International Nuclear Information System (INIS)

Frauke, A.; Wilkens, J.J.; Villagrasa, C.; Rabus, H.

2015-01-01

The BioQuaRT project within the European Metrology Research Programme aims at correlating ion track structure characteristics with the biological effects of radiation and develops measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigate methods to translate track-structure quantities derived on a nanometer scale to macroscopic dimensions. Input data sets were generated by simulations of ion tracks of protons and carbon ions in liquid water using the Geant-4 Monte Carlo tool-kit with the Geant-4-DNA processes. Based on the energy transfer points - recorded with nanometer resolution - we investigated parametrizations of overall properties of ion track structure. Three different track structure parametrizations have been developed using the distances to the 10 next neighbouring ionizations, the radial energy distribution and ionisation cluster size distributions. These parametrizations of nanometer-scale track structure build a basis for deriving biologically relevant mean values which are essential in the clinical situation where each voxel is exposed to a mixed radiation field. (authors)

Development of Selective Excitation Methods in Nuclear Magnetic Resonance: Investigation of Hemoglobin Oxygenation in Erythrocytes Using Proton and Phosphorus -31 Nuclear Magnetic Resonance

Science.gov (United States)

Fetler, Bayard Keith

1993-01-01

Nuclear magnetic resonance (NMR) offers a potential method for making measurements of the percent oxygenation of hemoglobin (Hb) in living tissue non-invasively. As a demonstration of the feasibility of such measurements, we measured the percent oxygenation of Hb in red blood cells (erythrocytes) using resonances in the proton-NMR (^1H-NMR) spectrum which are characteristic of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb), and are due to the unique magnetic properties of these molecules. To perform these measurements, we developed a new NMR method of selectively exciting signals in a region of interest with uniform phase and amplitude, while suppressing the signal of the water resonance. With this method, we are able to make exact calculations distinguishing between uniform phase excitation produced at large flip-angles using the non-linear properties of the Bloch equations, and uniform phase excitation produced at small flip-angles using asymmetric pulse excitation functions. We measured the percent oxygenation of three characteristic ^1H-NMR resonances of Hb: two from deoxy-Hb, originating from the N_delta H protons of histidine residue F8, which occur at different frequencies for the alpha and beta chains of Hb; and one from oxy-Hb, originating from the gamma_2 -CH_3 protons of valine residue E11. We performed experiments both on fresh erythrocytes and on erythrocytes depleted of 2,3-diphosphoglycerate (2,3-DPG), and found that oxygen is more tightly bound to Hb in the former case. In both fresh and 2,3-DPG-depleted samples, we found that: (i) from the deoxy-Hb marker resonances, there is a small but significant difference in the oxygen saturation between the alpha and beta chains; (ii) the decrease in the areas of the deoxy-Hb marker resonances correlates well with the increase in the percent oxygenation of Hb as measured optically; (iii) the area of the oxy-Hb marker resonance may be up to ~15% less than the optically measured Hb saturation. We are

Polarized Proton Collisions at RHIC

CERN Document Server

Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

2005-01-01

The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

ESTAR, PSTAR, ASTAR. A PC package for calculating stopping powers and ranges of electrons, protons and helium ions. Version 2

International Nuclear Information System (INIS)

Berger, M.J.

1993-01-01

A PC package is documented for calculating stopping powers and ranges of electrons, protons and helium ions in matter for energies from 1 keV up to 10 GeV. Stopping powers and ranges for electrons can be calculated for any element, compound or mixture. Stopping powers and ranges of protons and helium ions can be calculated for 74 materials (26 elements and 48 compounds and mixtures). The files are stored on two HD diskettes in compressed form. Both executable files for IBM PC and Fortran-77 source files are provided. All three programs require 5.2 Mb of disk space. This set of two diskettes with detailed documentation is available upon request, cost free, from the IAEA Nuclear Data Section. (author). 25 refs, 4 tabs

Equilibration: Developing the Hard Core of the Piagetian Research Program.

Science.gov (United States)

Rowell, J.A.

1983-01-01

Argues that the status of the concept of equilibration is classified by considering Piagetian theory as a research program in the sense elaborated in 1974 by Lakatos. A pilot study was made to examine the precision and testability of equilibration in Piaget's 1977 model.(Author/RH)

LET dependence of GafChromic films and an ion chamber in low-energy proton dosimetry

International Nuclear Information System (INIS)

Kirby, Daniel; Parker, David; Green, Stuart; Hugtenburg, Richard; Wojnecki, Cecile; Palmans, Hugo

2010-01-01

Dosimetry using a PMMA phantom was performed in 15 and 29 MeV proton beams from the Birmingham cyclotron, with a Markus parallel-plate ionization chamber and GafChromic EBT and MD-V2-55 film. Simulations of the depth-dose curves were performed with FLUKA 2008.3 and MCNPX 2.5.0, which agreed almost perfectly with each other in range and only differed by 2% in the Bragg peak (BP) region. FLUKA was also used to calculate k Q factors for Markus chamber measurements as an improvement to the IAEA TRS-398 values in low-energy beams. FLUKA depth-dose simulations overestimate the BP height measured by ion chamber by about 10%, where the initial proton energy spread was estimated by fitting to the slope of the measured BP distal edge. Both GafChromic films showed an under-response in the BP compared to ion chamber; however, EBT exhibits this effect at lower energies than MD-V2-55. A possible reason for this is attributed to the shape and arrangement of the monomer particles being different in the active components of EBT and MD-V2-55. Relative effectiveness (RE) of both films is presented as functions of residual range R res in water and peak proton energy determined by FLUKA, with considerations for the spatial separation of the two active layers in each film. The proton energies at which RE reduces to 90% of maximum film response are 6.7 and 3.2 MeV for MD-V2-55 and EBT, respectively. Additionally, a beam quality correction factor (g Q,Q 0 ) is suggested for both GafChromic films, involving water-to-film stopping power ratios evaluated using ICRU recommendations, and a polymer yield factor G Q 0 /G Q . RE in this work is equated to the reciprocal of the polymer yield factor. The calculated values of (s w,film ) Q /(s w,film ) Q 0 are constant within 2.1% and 1.2% across the proton energy range of 1-300 MeV for EBT and MD-V2-55, respectively, so it is concluded that the polymer yield factor is the dominant factor causing the LET quenching effect.

Study of silicon doped with zinc ions and annealed in oxygen

Energy Technology Data Exchange (ETDEWEB)

Privezentsev, V. V., E-mail: v.privezentsev@mail.ru [Russian Academy of Sciences, Institute of Physics and Technology (Russian Federation); Kirilenko, E. P.; Goryachev, A. N. [Zelenograd, National Research University of Electronic Technology “MIET” (Russian Federation); Batrakov, A. A. [National Research University “MEI” (Russian Federation)

2017-02-15

The results of studies of the surface layer of silicon and the formation of precipitates in Czochralski n-Si (100) samples implanted with {sup 64}Zn{sup +} ions with an energy of 50 keV and a dose of 5 × 10{sup 16} cm{sup –2} at room temperature and then oxidized at temperatures from 400 to 900°C are reported. The surface is visualized using an electron microscope, while visualization of the surface layer is conducted via profiling in depth by elemental mapping using Auger electron spectroscopy. The distribution of impurity ions in silicon is analyzed using a time-of-flight secondary-ion mass spectrometer. Using X-ray photoelectron spectroscopy, the chemical state of atoms of the silicon matrix and zinc and oxygen impurity atoms is studied, and the phase composition of the implanted and annealed samples is refined. After the implantation of zinc, two maxima of the zinc concentration, one at the wafer surface and the other at a depth of 70 nm, are observed. In this case, nanoparticles of the Zn metal phase and ZnO phase, about 10 nm in dimensions, are formed at the surface and in the surface layer. After annealing in oxygen, the ZnO · Zn{sub 2}SiO{sub 4} and Zn · ZnO phases are detected near the surface and at a depth of 50 nm, respectively.

The study of PDMS surface treatment and it's applications by using proton beam

Energy Technology Data Exchange (ETDEWEB)

Baek, J. Y.; Kim, J. Y.; Kwon, K. H.; Park, J. Y. [Korea Univ., Seoul (Korea, Republic of)

2007-04-15

PDMS(Polydimethylsiloxane) is mainly used as a material to do lab on a chip for biochemical analysis. PDMS has many applicability at the Bio-Technology(BT) field, because it is flexible, biocompatible and has good oxygen permeability. In this study, we have investigated to physical and chemical changes of PDMS surface by proton beam radiation conditions. The used kind of ion were Ar and N, beam energy was 30keV, 60keV, 80keV, total fluence was 1E10 to 1E16 [ions/cm{sup 2}]. PDMS membrane was produced as 150 {mu}m thick on the 3' silicon wafer. We inquired into physical and chemical changes up to beam radiation conditions through the investigate the change of surface roughness by AFM(Atomic Force Microscope), the change of surface morphology by SEM(Scanning Electron Microscope) and the change of chemical composition by FT-IR(Fourier Transform Infrared Raman spectroscopy) and XPS(X-ray Photoelectron Spectroscopy). From these basic data to we set up the proton beam radiation conditions to secure metal layer and PDMS adhesion. This enables to produce the electrode at the PDMS material lab on a chip. From now on, we'll investigate the cell patterning possibility after carry out of cell culture with mouse fibroblast at PDMS surface what is surface modification by using of proton beam radiation and apply this to produce lab on a chip. Physical property: Surface roughness of PDMS membrane was observed using AFM, after exposure of proton beam on it. The roughness increased as the power level of proton beam increase. This phenomena was caused by the kinetic energy of particle. Chemical property: Long term observation was conducted on the contact angles of the samples made by the proton beam exposure or oxygen plasma treatment; the hydrophilicity was found to be stronger in the samples made by the proton beam exposure. We found the reason of this was the destruction of polymer chains by proton beam. Feasibility of Through-hole: Considering that comparatively high

MEIC Proton Beam Formation with a Low Energy Linac

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuhong [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

2015-09-01

The MEIC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low-energy protons and ions into the booster ring.

A multi-satellite study of accelerated ionospheric ion beams above the polar cap

Directory of Open Access Journals (Sweden)

R. Maggiolo

2006-07-01

Full Text Available This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5–9 R_E. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio E_O+ / E_H+, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity.

In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5 Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H⁺ and O⁺. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability.

Oxygen sensitization of mammalian cells under different irradiation conditions

International Nuclear Information System (INIS)

Ling, C.C.; Michaels, H.B.; Gerweck, L.E.; Epp, E.R.; Peterson, E.C.

1981-01-01

The oxygen dependence of the radiosensitivity of cultured CHO cells was examined in detail with particular attention paid to avoiding possible artifacts due to radiolytic oxygen depletion. Two methods of gas equilibration and irradiation were used. In the first approach, cells were irradiated with 50-kVp X rays in a thin-layer geometry which offered maximum interchange between the cells and the surrounding gas. The second technique employed 280-kVp X irradiation of cells under full-medium conditions with mechanical agitation to minimize the effect of radiochemical oxygen consumption by promoting rapid oxygen replenishment. With these techniques oxygen radiosensitization was clearly resolved at an oxygen concentration of 0.03% in the gas phase. The oxygen K curves measured by these two methods were similar in shape over a wide range of oxygen concentration

The O-H Bond Dissociation Energies of Substituted Phenols and Proton Affinities of Substituted Phenoxide Ions: A DFT Study

Directory of Open Access Journals (Sweden)

Tadafumi Uchimaru

2002-04-01

Full Text Available Abstract: The accurate O-H bond dissociation enthalpies for a series of meta and para substituted phenols (X-C6H4-OH, X=H, F, Cl, CH3, OCH3, OH, NH2, CF3, CN, and NO2 have been calculated by using the (ROB3LYP procedure with 6-311G(d,p and 6-311++G(2df,2p basis sets. The proton affinities of the corresponding phenoxide ions (XC6H4-O- have also been computed at the same level of theory. The effect of change of substituent position on the energetics of substituted phenols has been analyzed. The correlations of Hammett’s substituent constants with the bond dissociation enthalpies of the O-H bonds of phenols and proton affinities of phenoxide ions have been explored.

Hacking the thylakoid proton motive force for improved photosynthesis: modulating ion flux rates that control proton motive force partitioning into Δψ and ΔpH.

Science.gov (United States)

Davis, Geoffry A; Rutherford, A William; Kramer, David M

2017-09-26

There is considerable interest in improving plant productivity by altering the dynamic responses of photosynthesis in tune with natural conditions. This is exemplified by the 'energy-dependent' form of non-photochemical quenching ( q E ), the formation and decay of which can be considerably slower than natural light fluctuations, limiting photochemical yield. In addition, we recently reported that rapidly fluctuating light can produce field recombination-induced photodamage (FRIP), where large spikes in electric field across the thylakoid membrane (Δ ψ ) induce photosystem II recombination reactions that produce damaging singlet oxygen ( 1 O 2 ). Both q E and FRIP are directly linked to the thylakoid proton motive force ( pmf ), and in particular, the slow kinetics of partitioning pmf into its ΔpH and Δ ψ components. Using a series of computational simulations, we explored the possibility of 'hacking' pmf partitioning as a target for improving photosynthesis. Under a range of illumination conditions, increasing the rate of counter-ion fluxes across the thylakoid membrane should lead to more rapid dissipation of Δ ψ and formation of ΔpH. This would result in increased rates for the formation and decay of q E while resulting in a more rapid decline in the amplitudes of Δ ψ -spikes and decreasing 1 O 2 production. These results suggest that ion fluxes may be a viable target for plant breeding or engineering. However, these changes also induce transient, but substantial mismatches in the ATP : NADPH output ratio as well as in the osmotic balance between the lumen and stroma, either of which may explain why evolution has not already accelerated thylakoid ion fluxes. Overall, though the model is simplified, it recapitulates many of the responses seen in vivo , while spotlighting critical aspects of the complex interactions between pmf components and photosynthetic processes. By making the programme available, we hope to enable the community of photosynthesis

Contribution of proton leak to oxygen consumption in skeletal muscle during intense exercise is very low despite large contribution at rest.

Directory of Open Access Journals (Sweden)

Bernard Korzeniewski

Full Text Available A computer model was used to simulate the dependence of protonmotive force (Δp, proton leak and phenomenological (involving proton leak ATP/O2 ratio on work intensity in skeletal muscle. Δp, NADH and proton leak decreased with work intensity. The contribution of proton leak to oxygen consumption ([Formula: see text] decreased from about 60% at rest to about 3 and 1% at moderate and heavy/severe exercise, respectively, while the ATP/O2 ratio increased from 2.1 to 5.5 and 5.7. A two-fold increase in proton leak activity or its decrease to zero decreased/increased the ATP/O2 ratio by only about 3 and 1% during moderate and heavy/severe exercise, respectively. The low contribution of proton leak to [Formula: see text] in intensively working skeletal muscle was mostly caused by a huge increase in ATP usage intensity during rest-to-work transition, while OXPHOS, and thus oxidative ATP supply and [Formula: see text] related to it, was mostly stimulated by high each-step activation (ESA of OXPHOS complexes. The contribution of proton leak to [Formula: see text] and ATP/O2 ratio in isolated mitochondria should not be directly extrapolated to working muscle, as mitochondria lack ESA, at least in the absence of Ca2+, and therefore [Formula: see text] cannot be elevated as much as in intact muscle.

Hydrogen and oxygen behaviors on Porous-Si surfaces observed using a scanning ESD ion microscope

International Nuclear Information System (INIS)

Itoh, Yuki; Ueda, Kazuyuki

2004-01-01

A scanning electron-stimulated desorption (ESD) ion microscope (SESDIM) measured the 2-D images of hydrogen and oxygen distribution on solid surfaces. A primary electron beam at 600 eV, with a pulse width of 220 ns, resulted in ion yields of H + and O + . This SESDIM is applied to the surface analysis of Porous-Si (Po-Si) partially covered with SiN films. During the heating of a specimen of the Po-Si at 800 deg. C under ultra-high-vacuum (UHV) conditions, the components of the surface materials were moved or diffused by thermal decomposition accompanied by a redistribution of hydrogen and oxygen. After cyclic heating of above 800 deg. C, the dynamic behaviors of H + and O + accompanied by the movements of the SiN layers were observed as images of H + and O + . This was because the H + and O + ions have been identified as composite materials by their kinetic energies

Investigation of oxygen distribution in HTSC-insulator in film structures on light ion beam

International Nuclear Information System (INIS)

Verbitskaya, E.M.; Grekhov, I.V.; Eremin, V.K.; Konnikov, S.G.; Linijchuk, I.A.; Razumov, S.V.; Semchinova, O.K.; Strokan, N.B.; Dyumin, A.N.; Lebedev, V.M.

1992-01-01

Use of nuclear reaction method on accelerated ions for profiling of oxygen concentration in thin-film HTSC structures is considered. Reaction on 16 O(d, α) 14 N deuterons, in course of which ∼ 2.6 MeV α-particles are generated, is used. Detected in experiment 2.0-2.6 MeV α-particle spectrum permits to recognstruct oxygen concentration profile in sample depth. Results obtained on YBa 2 Cu 3 O 7-δ and Y 2 BaCuO 5 film om MgO sunstrates, relating to the case of both uniform and nonuniform oxygen distribution, are presented. Resolution in the depth ∼ 200 A and accuracy of concentration measurement (relatively MgO substrate) of several percents are attained during oxygen profiling

Time variations of magnetospheric intensities of outer zone protons, alpha particles and ions (Z greater than or equal to 2). Ph.D. Thesis

Science.gov (United States)

Randall, B. A.

1973-01-01

A comprehensive study of the temporal behavior of trapped protons, alpha particles and ions (Z 2) in outer zone of the earth's magnetosphere has been made. These observations were made by the Injun V satellite during the first 21 months of operation, August 1968 to May 1970. Rapid increases in the observed number of particles followed by slower exponential decay characterize the data. Comparisons are made with the temporal behavior of interplanetary particles of the same energy observed by Explorer 35. Increases in the trapped fluxes generally correspond to enhanced interplanetary activity. The energy spectra of protons and alpha particles at L = 3 have similar shapes when compared on an energy per charge basis while the respective polar cap spectra have similar shape on an energy per nucleon basis. Apparent inward trans-L motion of energetic protons is observed. These particles are diffused inward by a process involving fluctuating electric fields. The loss of trapped low altitude protons, alpha particles and ions (Z 2) is controlled by coulombic energy loss in the atmosphere.

Innershell ionization by fast protons, alpha particles and carbon ions

International Nuclear Information System (INIS)

Dijk, J.H. van.

1984-01-01

The subject of this thesis is the study of inner-shell excitations of atoms induced by fast charged particle collisions. A new method is described for measuring the spectrum of delta-electrons emitted by 208 Pb after excitation by 15 MeV protons or 50 MeV alpha particles. Experimental equipment is described. Results of both experiments are presented and compared with PWBA models and with calculations based on a semi-classical approximation. The small-impact-parameter ionization probabilities obtained are then compared with literature. Also small-impact-parameter measurements done with 100 MeV carbon ions are described. Besides K-shell measurements, the author also presents L-subshell ionization probability results for Pb. An appendix is added in which energy straggling problems in solid targets are treated. (Auth./G.J.P.)

Nonlinear MHD waves and discontinuities in the Martian magnetosheath. Observations and 2D bi-ion MHD simulations

Science.gov (United States)

Sauer, K.; Dubinin, E.; Baumgärtel, K.

1998-09-01

The characteristic scale of the Martian magnetosheath is less than the pick-up gyroradius of oxygen ions. This leads to admissible differential motion of protons and heavies and a strong coupling between both ion fluids. 2D bi-ion MHD simulations reveal many new interesting features in such Large Larmour Radius systems. The formation of an ion-composition boundary, which separates both plasmas, and structuring of the transition from proton dominated plasma of the solar wind origin to massive planetary plasma are the main features of the interaction. A comprehensive multi-instrument study of Martian plasma environment and the comparison with theoretical modelling initiated in the framework of the Visiting Science Programme of the International Space Science Institute (ISSI) in Bern (Switzerland) gives confirmation that Mars interacts with the solar wind like a comet which has a outgassing rate near to that of Grigg-Skjellerup. The results may also be relevant for small bodies which are surrounded by a neutral gas atmosphere (icy moons, asteroids, Mercury).

Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

International Nuclear Information System (INIS)

Smirnov, Evgeny; Peljo, Pekka; Scanlon, Micheál D.; Girault, Hubert H.

2016-01-01

ABSTRACT: Functionalization of a soft or liquid-liquid interface by a one gold nanoparticle thick “nanofilm” provides a conductive pathway to facilitate interfacial electron transfer from a lipophilic electron donor to a hydrophilic electron acceptor in a process known as interfacial redox catalysis. The gold nanoparticles in the nanofilm are charged by Fermi level equilibration with the lipophilic electron donor and act as an interfacial reservoir of electrons. Additional thermodynamic driving force can be provided by electrochemically polarising the interface. Using these principles, the biphasic reduction of oxygen by a lipophilic electron donor, decamethylferrocene, dissolved in α,α,α-trifluorotoluene was catalysed at a gold nanoparticle nanofilm modified water-oil interface. A recently developed microinjection technique was utilised to modify the interface reproducibly with the mirror-like gold nanoparticle nanofilm, while the oxidised electron donor species and the reduction product, hydrogen peroxide, were detected by ion transfer voltammetry and UV/vis spectroscopy, respectively. Metallization of the soft interface allowed the biphasic oxygen reduction reaction to proceed via an alternative mechanism with enhanced kinetics and at a significantly lower overpotential in comparison to a bare soft interface. Weaker lipophilic reductants, such as ferrocene, were capable of charging the interfacial gold nanoparticle nanofilm but did not have sufficient thermodynamic driving force to significantly elicit biphasic oxygen reduction.

Improved surface corrosion resistance of WE43 magnesium alloy by dual titanium and oxygen ion implantation

Energy Technology Data Exchange (ETDEWEB)

Zhao, Ying [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Guosong; Lu, Qiuyuan [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Jun [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Xu, Ruizhen [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Yeung, Kelvin W.K., E-mail: wkkyeung@hku.hk [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2013-02-01

Magnesium alloys are potential biodegradable materials and have attracted much attention due to their outstanding biological performance and mechanical properties. However, their rapid degradation inside the human body cannot meet clinical needs. In order to improve the corrosion resistance, dual titanium and oxygen ion implantation is performed to modify the surface of the WE43 magnesium alloy. X-ray photoelectron spectroscopy is used to characterize the microstructures in the near surface layer and electrochemical impedance spectroscopy, potentiodynamic polarization, and immersion tests are employed to investigate the corrosion resistance of the implanted alloys in simulated body fluids. The results indicate that dual titanium and oxygen ion implantation produces a TiO{sub 2}-containing surface film which significantly enhances the corrosion resistance of WE43 magnesium alloy. Our data suggest a simple and practical means to improve the corrosion resistance of degradable magnesium alloys. - Highlights: ► Surface modification of WE43 magnesium alloy using dual ion implantation ► Dual Ti and O ion implantation produces a homogeneous TiO{sub 2}-containing surface film ► Significant improvement of the alloy corrosion resistance after the dual ion implantation.

Proton and heavy ion beam (charged particle therapy)

International Nuclear Information System (INIS)

Kanai, Tatsuaki

2003-01-01

There are distinguished therapeutic irradiation facilities of proton and heavy ion beam in Japan. The beam, due to its physical properties, is advantageous for focusing on the lesion in the body and for reducing the exposure dose to normal tissues, relative to X-ray. This makes it possible to irradiate the target lesion with the higher dose. The present review describes physical properties of the beam, equipments for the therapeutic irradiation, the respiratory-gated irradiation system, the layer-stacking irradiation system, therapy planning, and future prospect of the therapy. More than 1,400 patients have received the therapy in National Institute of Radiological Sciences (NIRS) and given a good clinical outcome. The targets are cancers of the head and neck, lung, liver, uterine and prostate, and osteosarcoma. The therapy of osteosarcoma is particularly important, which bringing about the high cure rate. Severe adverse effects are not seen with exception for the digestive tract ulcer. Many attempts like the respiratory-gated and layer-stacking systems and to shorten the therapy period to within 1 week are in progress. (N.I.)

Location of protons in N-H···N hydrogen-bonded systems: a theoretical study on intramolecular pyridine-dihydropyridine and pyridine-pyridinium pairs.

Science.gov (United States)

Mori, Yukie; Takano, Keiko

2012-08-21

Two-dimensional potential energy surfaces (PESs) were calculated for the degenerate intramolecular proton transfer (PT) in two N-H···N hydrogen-bonded systems, (Z)-2-(2-pyridylmethylidene)-1,2-dihydropyridine (1) and monoprotonated di(2-pyridyl) ether (2), at the MP2/cc-pVDZ level of theory. The calculated PES had two minima in both cases. The energy barrier in 1 was higher than the zero-point energy (ZPE) level, while that in 2 was close to the ZPE. Vibrational wavefunctions were obtained by solving time-independent Schrödinger equations with the calculated PESs. The maximum points of the probability density were shifted from the energy minima towards the region where the covalent N-H bond was elongated and the N···N distance shortened. The effects of a polar solvent on the PES were investigated with the continuum or cluster models in such a way that the solute-solvent electrostatic interactions could be taken into account under non-equilibrated conditions. A solvated contact ion-pair was modelled by a cluster consisting of one cation 2, one chloride ion and 26 molecules of acetonitrile. The calculation with this model suggested that the bridging proton is localised in the deeper well due to the significant asymmetry of the PES and the high potential barrier.

Production of high-brightness continuous wave proton beams with very high proton fractions (abstract)a

International Nuclear Information System (INIS)

Spence, D.; McMichael, G.; Lykke, K.R.; Schneider, J.D.; Sherman, J.; Stevens, R. Jr.; Hodgkins, D.

1996-01-01

This article demonstrates a new technique to significantly enhance the proton fraction of an ion beam extracted from a plasma ion source. We employ a magnetically confined microwave driven source, though the technique is not source specific and can probably be applied equally effectively to other plasma sources such as Penning and multicusp types. Specifically, we dope the plasma with about 1% H 2 O, which increases the proton fraction of a 45 keV 45 mA beam from 75% to 90% with 375 W 2.45 GHz power to the source and from 84% to 92% for 500 W when the source is operated under nonresonant conditions. Much of the remaining fraction of the beam comprises a heavy mass ion we believe to be N + impurity ions resulting from the conditions under which the experiments were performed. If so, this impurity can easily be removed and much higher proton fractions could be expected. Preliminary measurements show the additive has no adverse effect on the emittance of the extracted beam, and source stability is greatly improved

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

International Nuclear Information System (INIS)

Gudmundsson, J T

2004-01-01

A global (volume averaged) model of oxygen discharges is used to study the transition from a recombination dominated discharge to a detachment dominated discharge. The model includes the metastable oxygen molecules O 2 (a 1 Δ g ) and O 2 (b 1 Σ g + ) and the three Herzberg states O 2 (A 3 Σ u + , A' 3 Δ u , c 1 Σ u - ). Dissociative attachment of the oxygen molecule in the ground state O 2 ( 3 Σ g - ) and the metastable oxygen molecule O 2 (a 1 Δ g ) are the dominating channels for creation of the negative oxygen ion O - . At high pressures, dissociative attachment of the Herzberg states contributes significantly to the creation of the negative oxygen ion, O - . The detachment by a collision of the metastable oxygen molecule O 2 (b 1 Σ g + ) with the oxygen ion, O - , is a significant loss process for the O - at pressures above 10 mTorr. Its contribution to the loss is more significant at a lower applied power, but at the higher pressures it is always significant. Detachment by collision with O( 3 P) is also an important loss mechanism for O - . We find that ion-ion recombination is the dominating loss process for negative ions in oxygen discharges at low pressures and calculate the critical pressure where the contributions of recombination reactions and detachment reactions are equal. This critical pressure depends on the applied power, increases with applied power and is in the range 5-14 mTorr in the pressure and power range investigated

Pickup Ions in the Plasma Environments of Mars, Comets, and Enceladus

Science.gov (United States)

Cravens, T.; Rahmati, A.; Sakai, S.; Madanian, H.; Larson, D. E.; Lillis, R. J.; Halekas, J. S.; Goldstein, R.; Burch, J. L.; Clark, G. B.; Jakosky, B. M.

2015-12-01

Ions created within a flowing plasma by ionization of neutrals respond to the electric and magnetic fields associated with the flow becoming what are called pick-up ions (PUI). PUI play an important role in many solar system plasma environments and affect the energy and momentum balance of the plasma flow. PUI have been observed during several recent space missions and PUI data will be compared and interpreted using models. Pick-up oxygen ions were observed in the solar wind upstream of Mars by the Solar Energetic Particle (SEP) and Solar Wind Ion Analyzer (SWIA) instruments on NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. The pick-up oxygen ions are created when atoms in the hot corona are ionized by solar radiation and charge exchange with solar wind protons. The ion fluxes measured by SEP can constrain the oxygen escape rate from Mars. PUI were also been detected at distances of 10 - 100 km from the nucleus of comet 67P/Churyumov- Gerasimenko (67P/CG) by plasma instruments (IES and ICA) onboard the Rosetta Orbiter when the comet was at 3 AU. The newly-born cometary ions are accelerated by the solar wind motional electric field but remain un-magnetized, as suggested by pre-encounter models (Rubin et al., 2014). The inner magnetosphere of Saturn and the water plume of the icy satellite Enceladus provide a third example of PUI. H2O+ ions created by ionization of neutral water producing ions that are picked-up by the co-rotating magnetospheric plasma flow. These ions then undergo a complex interaction with the plume gas including collisions that convert most H2O+ ions to H3O+, as measured by the Ion and Neutral Mass Spectrometer (INMS) onboard the Cassini spacecraft.

Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

KAUST Repository

Alquaity, Awad B. S.; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

2017-01-01

chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

The FAIR proton linac

International Nuclear Information System (INIS)

Kester, O.

2015-01-01

FAIR - the Facility for Antiproton and Ion Research in Europe - constructed at GSI in Darmstadt comprises an international centre of heavy ion accelerators that will drive heavy ion and antimatter research. FAIR will provide worldwide unique accelerator and experimental facilities, allowing a large variety of fore-front research in physics and applied science. FAIR will deliver antiproton and ion beams of unprecedented intensities and qualities. The main part of the FAIR facility is a sophisticated accelerator system, which delivers beams to different experiments of the FAIR experimental collaborations - APPA, NuSTAR, CBM and PANDA - in parallel. Modern H-type cavities offer highest shunt impedances of resonant structures of heavy ion linacs at low beam energies < 20 MeV/u and enable the acceleration of intense proton and ion beams. One example is the interdigital H-type structure. The crossed-bar H-cavities extend these properties to high energies even beyond 100 MeV/u. Compared to conventional Alvarez cavities, these crossed-bar (CH) cavities feature much higher shunt impedance at low energies. The design of the proton linac is based on those cavities

Heavy ion scattering; a fixed energy inverse problem

International Nuclear Information System (INIS)

Amos, K.

1993-01-01

Heavy ion scattering has been studied quite intensively in the last decade and central in most analyses of data from such experiments be they on fusion, particle transfer or internal state excitations of the colliding pair, is the inter-ion interaction affecting their relative motion. It is customary to use the elastic scattering data to constrain solutions of the (nonrelativistic) Schroedinger equation to ascertain the character of that (central and complex) heavy ion potential. These matters for projectiles ranging from the lightest 'heavy' ion, a proton, to Oxygen nuclei are considered in brief herein. The targets range from 12 C to 208 Pb. The central entity in the analyses to be discussed will be the S-function, and so for completeness, the simple potential scattering theory details are presented that specify the S-function and relate it to measured cross-sections. 20 refs., 18 figs

Proton gradients and proton-dependent transport processes in the chloroplast

Directory of Open Access Journals (Sweden)

Ricarda eHöhner

2016-02-01

Full Text Available Proton gradients are fundamental to chloroplast function. Across thylakoid membranes, the light induced proton gradient is essential for ATP synthesis. As a result of proton pumping into the thylakoid lumen, an alkaline stromal pH develops, which is required for full activation of pH-dependent Calvin Benson cycle enzymes. This implies that a pH gradient between the cytosol (pH 7 and the stroma (pH 8 is established upon illumination. To maintain this pH gradient chloroplasts actively extrude protons. More than 30 years ago it was already established that these proton fluxes are electrically counterbalanced by Mg2+, K+ or Cl- fluxes, but only recently the first transport systems that regulate the pH gradient were identified. Notably several (Na+,K+/H+ antiporter systems where identified, that play a role in pH gradient regulation, ion homeostasis, osmoregulation, or coupling of secondary active transport. The established pH gradients are important to drive uptake of essential ions and solutes, but not many transporters involved have been identified to date. In this mini review we summarize the current status in the field and the open questions that need to be addressed in order to understand how pH gradients are maintained, how this is interconnected with other transport processes and what this means for chloroplast function.

Accurate and precise measurement of oxygen isotopic fractions and diffusion profiles by selective attenuation of secondary ions (SASI).

Science.gov (United States)

Téllez, Helena; Druce, John; Hong, Jong-Eun; Ishihara, Tatsumi; Kilner, John A

2015-03-03

The accuracy and precision of isotopic analysis in Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) relies on the appropriate reduction of the dead-time and detector saturation effects, especially when analyzing species with high ion yields or present in high concentrations. Conventional approaches to avoid these problems are based on Poisson dead-time correction and/or an overall decrease of the total secondary ion intensity by reducing the target current. This ultimately leads to poor detection limits for the minor isotopes and high uncertainties of the measured isotopic ratios. An alternative strategy consists of the attenuation of those specific secondary ions that saturate the detector, providing an effective extension of the linear dynamic range. In this work, the selective attenuation of secondary ion signals (SASI) approach is applied to the study of oxygen transport properties in electroceramic materials by isotopic labeling with stable (18)O tracer and ToF-SIMS depth profiling. The better analytical performance in terms of accuracy and precision allowed a more reliable determination of the oxygen surface exchange and diffusion coefficients while maintaining good mass resolution and limits of detection for other minor secondary ion species. This improvement is especially relevant to understand the ionic transport mechanisms and properties of solid materials, such as the parallel diffusion pathways (e.g., oxygen diffusion through bulk, grain boundary, or dislocations) in electroceramic materials with relevant applications in energy storage and conversion devices.

Chemical dynamics of the first proton-coupled electron transfer of water oxidation on TiO2 anatase.

Science.gov (United States)

Chen, Jia; Li, Ye-Fei; Sit, Patrick; Selloni, Annabella

2013-12-18

Titanium dioxide (TiO2) is a prototype, water-splitting (photo)catalyst, but its performance is limited by the large overpotential for the oxygen evolution reaction (OER). We report here a first-principles density functional theory study of the chemical dynamics of the first proton-coupled electron transfer (PCET), which is considered responsible for the large OER overpotential on TiO2. We use a periodic model of the TiO2/water interface that includes a slab of anatase TiO2 and explicit water molecules, sample the solvent configurations by first principles molecular dynamics, and determine the energy profiles of the two electronic states involved in the electron transfer (ET) by hybrid functional calculations. Our results suggest that the first PCET is sequential, with the ET following the proton transfer. The ET occurs via an inner sphere process, which is facilitated by a state in which one electronic hole is shared by the two oxygen ions involved in the transfer.

Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

Energy Technology Data Exchange (ETDEWEB)

Wetteland, C. J.; Field, K. G.; Gerczak, T. J. [Materials Science Program, University of Wisconsin, Madison, WI 53706 (United States); Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R. [Department of Engineering Physics, University of Wisconsin, Madison, WI 53706 (United States)

2013-04-19

The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150{mu}A of proton current from the source, with over 70{mu}A on the target stage. However, beam fluxes above {approx}1 Multiplication-Sign 10{sup 17}/m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

Photon production in an expanding and chemically equilibrating gluon-enriched plasma

International Nuclear Information System (INIS)

Kaempfer, B.; Technische Univ. Dresden; Pavlenko, O.P.; AN Ukrainskoj SSR, Kiev

1993-12-01

Photon production in a longitudinally and transversely expanding gluon plasma with initially little quark admixture is considered. Chemical equilibration of quarks and gluons is followed by rate equations. The yields of hard photons with E ≥ 2 GeV are insensitive to chemical equilibration and depend mainly on the initial thermalized state. Medium-energy photons with E ∼ 1 GeV are more frequently produced in case of faster equilibration, despite of faster cooling. For an assumed fast equilibration we follow the evolution of matter through mixed and hadron phases. The transverse momentum kick, due to transverse expansion, of photons from hadron matter is shown to be reduced for an equation of state with reduced latent heat. The photon yield in the region E > 1 GeV from deconfined matter dominates for conditions, estimated to be achieved at RHIC, in case of a weakly first-order confinement transition. (orig.)

The heavy ion diffusion region in magnetic reconnection in the Earth's magnetotail

Science.gov (United States)

Liu, Y. H.; Mouikis, C. G.; Kistler, L. M.; Wang, S.; Roytershteyn, V.; Karimabadi, H.

2015-05-01

While the plasma in the Earth's magnetotail predominantly consists of protons and electrons, there are times when a significant amount of oxygen is present. When magnetic reconnection occurs, the behavior of these heavy ions can be significantly different from that of the protons, due to their larger gyroradius. In this study, we investigate the heavy ion distribution functions in the reconnection ion diffusion region from a 2.5D three-species particle-in-cell numerical simulation and compare those with Cluster observations from the near-Earth magnetotail. From the simulation results, we find that the heavy ions are demagnetized and accelerated in a larger diffusion region, the heavy ion diffusion region. The ion velocity distribution functions show that, inside the heavy ion diffusion region, heavy ions appear as counterstreaming beams along z in the GSM x-z plane, while drifting in y, carrying cross-tail current. We compare this result with Cluster observations in the vicinity of reconnection regions in the near-Earth magnetotail and find that the simulation predictions are consistent with the observed ion distribution functions in the ion diffusion region, as well as the inflow, exhaust, and separatrix regions. Based on the simulation and observation results, the presence of a multiscale diffusion region model, for O+ abundant reconnection events in the Earth's magnetotail, is demonstrated. A test particle simulation shows that in the diffusion region, the H+ gains energy mainly through Ex, while the O+ energy gain comes equally from Ex and Ey.

Collision-Induced Dissociation of Deprotonated Peptides. Relative Abundance of Side-Chain Neutral Losses, Residue-Specific Product Ions, and Comparison with Protonated Peptides.

Science.gov (United States)

Liang, Yuxue; Neta, Pedatsur; Yang, Xiaoyu; Stein, Stephen E

2018-03-01

High-accuracy MS/MS spectra of deprotonated ions of 390 dipeptides and 137 peptides with three to six residues are studied. Many amino acid residues undergo neutral losses from their side chains. The most abundant is the loss of acetaldehyde from threonine. The abundance of losses from the side chains of other amino acids is estimated relative to that of threonine. While some amino acids lose the whole side chain, others lose only part of it, and some exhibit two or more different losses. Side-chain neutral losses are less abundant in the spectra of protonated peptides, being significant mainly for methionine and arginine. In addition to the neutral losses, many amino acid residues in deprotonated peptides produce specific negative ions after peptide bond cleavage. An expanded list of fragment ions from protonated peptides is also presented and compared with those of deprotonated peptides. Fragment ions are mostly different for these two cases. These lists of fragments are used to annotate peptide mass spectral libraries and to aid in the confirmation of specific amino acids in peptides. Graphical Abstract ᅟ.

Theoretical and experimental investigation of carnosine and its oxygenated adducts. The reaction with the nickel ion

Energy Technology Data Exchange (ETDEWEB)

Pavlos, Dimitrios; Petropouleas, Panayiotis; Hatzipanayioti, Despina, E-mail: stambaki@chem.uoa.gr

2015-11-05

Highlights: • Study on models of neutral cations and anions of carnosine at the B3LYP/TZVP level. • The {sup 1}O{sub 2}-adducts of these models resulted in oxygenated carnosine. • Theoretical parameters correlated to experimental results for carn and carn-H{sub 2}O{sub 2}. • Theoretical models of Nickel-carn complexes have been investigated. • Isolation and characterization of the solid [Ni(carn){sub 2}(H{sub 2}O){sub 5}] have been performed. - Abstract: DFT theoretical calculations at B3LYP/TZVP or LANL2DZ level of theory, for neutral, zwitterions, protonated and anionic carnosine, were performed. Energies, the structural and spectroscopic parameters were calculated in the gas phase and aqueous medium. Additional H-bonds stabilize the ionized forms of carnosine, creating “nests” into which metal ions or bio-molecules may be sheltered. Based on Fukui functions, the reactivity of the abovementioned forms of carnosine, with {sup 1}O{sub 2}, may lead to oxygenated species. The theoretical spectroscopic parameters have been correlated to our experimental results. The effect of H{sub 2}O{sub 2} and the electrochemistry of aqueous carnosine solutions were examined. Theoretical models containing Ni(II), carnosine and water were constructed. In the isolated mauve solid, formulated [Ni(carn){sub 2}(H{sub 2}O){sub 5}], the COO−, N{sub π} and/or NH{sub 2} were bonded. When H{sub 2}O{sub 2} was added, the imidazole NMR signals disappeared. A redox couple clearly indicates one electron process, the electron coming from either the oxidation of imidazole ring or the nickel(II)/Ni(III) couple.

High Rate and Stable Li-Ion Insertion in Oxygen-Deficient LiV3O8 Nanosheets as a Cathode Material for Lithium-Ion Battery.

Science.gov (United States)

Song, Huanqiao; Luo, Mingsheng; Wang, Aimei

2017-01-25

Low performance of cathode materials has become one of the major obstacles to the application of lithium-ion battery (LIB) in advanced portable electronic devices, hybrid electric vehicles, and electric vehicles. The present work reports a versatile oxygen-deficient LiV 3 O 8 (D-LVO) nanosheet that was synthesized successfully via a facile oxygen-deficient hydrothermal reaction followed by thermal annealing in Ar. When used as a cathode material for LIB, the prepared D-LVO nanosheets display remarkable capacity properties at various current densities (a capacity of 335, 317, 278, 246, 209, 167, and 133 mA h g -1 at 50, 100, 200, 500, 1000, 2000, and 4000 mA g -1 , respectively) and excellent lithium-ion storage stability, maintaining more than 88% of the initial reversible capacity after 200 cycles at 1000 mA g -1 . The outstanding electrochemical properties are believed to arise largely from the introduction of tetravalent V (∼15% V 4+ ) and the attendant oxygen vacancies into LiV 3 O 8 nanosheets, leading to intrinsic electrical conductivity more than 1 order of magnitude higher and lithium-ion diffusion coefficient nearly 2 orders of magnitude higher than those of LiV 3 O 8 without detectable V 4+ (N-LVO) and thus contributing to the easy lithium-ion diffusion, rapid phase transition, and the excellent electrochemical reversibility. Furthermore, the more uniform nanostructure, as well as the larger specific surface area of D-LVO than N-LVO nanosheets may also improve the electrolyte penetration and provide more reaction sites for fast lithium-ion diffusion during the discharge/charge processes.

Si-O compound formation by oxygen ion implantation into silicon

International Nuclear Information System (INIS)

Hensel, E.; Wollschlaeger, K.; Kreissig, U.; Skorupa, W.; Schulze, D.; Finster, J.

1985-01-01

High dose oxygen ion implantation into silicon at 30 keV was performed to produce understoichiometric and stoichiometric surface oxide layers of approx. 160 nm thickness. The oxygen depth profile and oxide stoichiometry was determined by RBS and XPS. Si-O compound formation was found by IR spectroscopy and XPS in the unannealed samples as well as after target heating, furnace or flash lamp annealing. As implanted understoichiometric layers consist of random bonding like SiOsub(x) (O 2 after annealing. Unannealed stoichiometric layers are bond strained SiO 2 . The activation energies of demixing and of the annealing of bond strains are determined to 0.19 and 0.13 eV, respectively. The removing of bond strains occurs at temperatures >= 800 C in a time shorter than 1 s. The SiO 2 /Si transition region of unannealed stoichiometric layers consists of SiOsub(x) with an extent of about 10 nm. After annealing this extent diminishes to 0.8 to 1 nm in consequence of oxidation by excess oxygen from the overstoichiometric oxide region. This thickness is comparable with that of thermal oxide. (author)

Molecular dynamics and brownian dynamics investigation of ion permeation and anesthetic halothane effects on a proton-gated ion channel.

Science.gov (United States)

Cheng, Mary Hongying; Coalson, Rob D; Tang, Pei

2010-11-24

Bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC) is activated to cation permeation upon lowering the solution pH. Its function can be modulated by anesthetic halothane. In the present work, we integrate molecular dynamics (MD) and Brownian dynamics (BD) simulations to elucidate the ion conduction, charge selectivity, and halothane modulation mechanisms in GLIC, based on recently resolved X-ray crystal structures of the open-channel GLIC. MD calculations of the potential of mean force (PMF) for a Na(+) revealed two energy barriers in the extracellular domain (R109 and K38) and at the hydrophobic gate of transmembrane domain (I233), respectively. An energy well for Na(+) was near the intracellular entrance: the depth of this energy well was modulated strongly by the protonation state of E222. The energy barrier for Cl(-) was found to be 3-4 times higher than that for Na(+). Ion permeation characteristics were determined through BD simulations using a hybrid MD/continuum electrostatics approach to evaluate the energy profiles governing the ion movement. The resultant channel conductance and a near-zero permeability ratio (P(Cl)/P(Na)) were comparable to experimental data. On the basis of these calculations, we suggest that a ring of five E222 residues may act as an electrostatic gate. In addition, the hydrophobic gate region may play a role in charge selectivity due to a higher dehydration energy barrier for Cl(-) ions. The effect of halothane on the Na(+) PMF was also evaluated. Halothane was found to perturb salt bridges in GLIC that may be crucial for channel gating and open-channel stability, but had no significant impact on the single ion PMF profiles.

A Study of Ion-Ion Hybrid Instability in the Mixed Plasma

Directory of Open Access Journals (Sweden)

Soo-Yong Kim

1987-12-01

Full Text Available There are more oxygen ions than hydrogen ions in the auroral field zone. We consider both analytic and numerical simulation study of the heating of hydrogen and oxygen ions by auroral electrons. With the low drift speed of electron beams, the ion-ion hybrid wave becomes unstable instead of the lower hybrid wave so that a preferential heating of oxygen ions occurs.

[Ion channels that are sensitive to the extracellular concentration of protons: their structure, function, pharmacology and pathophysiology].

Science.gov (United States)

Mercado, F; Vega, R; Soto, E

Acid sensing ion channels (ASIC) members of the ENaC degenerine channel family, have been shown to participate in various sensorial pathways including nociception, also they have been shown to participate in synaptic transmission, learning and memory processes and in the physiopathology of the ischemic stroke. The proton concentration in the organism is strictly regulated by distinct buffer systems. Drastic changes of pH are generated only by pathological conditions as is the ischemia; however, some physiological processes may produce local changes in the extracellular pH. Recently, a new family of proton receptors known as ASIC has been cloned. These are ionic channels inactivated at physiological pH (7.4) and activated with a pH fall (increase in H+ concentration). ASICs are permeable to sodium ions and in a lesser degree to calcium ions, activation of these channels leads to an increase in cell excitability. The ASICs are distributed widely in the central and peripheral nervous system, and in specialized epithelia. In the past few years they have become a focus of interest due to its role in nociception, taste perception, long term potentation and the physiopathology of ischemic stroke. In this review we address the most relevant molecular, physiological and pharmacological aspects of the ASICs, its participation in some pathological process, and the perspectives of basic and clinic investigation in this arising research field.

[Effect of high magnesium ion concentration on the electron transport rate and proton exchange in thylakoid membranes in higher plants].

Science.gov (United States)

Ignat'ev, A R; Khorobrykh, S A; Ivanov, B N

2001-01-01

The effects of magnesium ion concentration on the rate of electron transport in isolated pea thylakoids were investigated in the pH range from 4.0 up to 8.0. In the absence of magnesium ions in the medium and in the presence of 5 mM MgCl2 in the experiments not only without added artificial acceptors but also with ferricyanide or methylviologen as an acceptor, this rate had a well-expressed maximum at pH 5.0. It was shown that, after depression to minimal values at pH 5.5-6.5, it gradually rose with increasing pH. An increase in magnesium ion concentration up to 20 mM essentially affected the electron transfer rate: it decreased somewhat at pH 4.0-5.0 but increased at higher pH values. At this magnesium ion concentration, the maximum rate was at pH 6.0-6.5 and the minimum, at pH 7.0. Subsequent rise upon increasing pH to 8.0 was expressed more sharply. The influence of high magnesium ion concentration on the rate of electron transport was not observed in the presence of gramicidin D. It was found that without uncoupler, the changes in the electron transfer rate under the influence of magnesium ions correlated to the changes in the first-order rate constant of the proton efflux from thylakoids. It is supposed that the change in the ability of thylakoids to keep protons by the action of magnesium ions is the result of electrostatic interactions of these ions with the charges on the external surface of membranes. A possible role of regulation of the electron transport rate by magnesium ions in vivo is discussed.

Measurement of omega, the energy required to create an ion pair, for 150-MeV protons in nitrogen and argon

International Nuclear Information System (INIS)

Petti, P.L.

1985-01-01

The purpose of this thesis is to provide a 1% measurement of omega, the energy required to produce an ion pair, for 150 MeV protons in various gases. Such a measurement should improve the accuracy of proton ionization chamber dosimetry at the Harvard Cyclotron Laboratory. Currently, no measurements of omega exist in the energy range of 30 to 150 MeV, and present ionization chamber dosimetry at the Cyclotron relies on average values of measurements at lower and higher energies (i.e. for E < 3 MeV and E = 340 MeV). Contrary to theoretical expectations, these low and high energy data differ by as much as 9% in some gases. The results of this investigation demonstrate that the existing high energy data is probably in error, and current proton ionization chamber dosimetry underestimates omega, and hence the proton dose, by 5%

LET dependence of GafChromic films and an ion chamber in low-energy proton dosimetry

Energy Technology Data Exchange (ETDEWEB)

Kirby, Daniel; Parker, David [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Green, Stuart; Hugtenburg, Richard; Wojnecki, Cecile [Department of Medical Physics, University Hospital Birmingham NHS Trust, Birmingham, B15 2TH (United Kingdom); Palmans, Hugo [National Physical Laboratory, Acoustics and Ionizing Radiation, Teddington (United Kingdom)], E-mail: djk191@bham.ac.uk

2010-01-21

Dosimetry using a PMMA phantom was performed in 15 and 29 MeV proton beams from the Birmingham cyclotron, with a Markus parallel-plate ionization chamber and GafChromic EBT and MD-V2-55 film. Simulations of the depth-dose curves were performed with FLUKA 2008.3 and MCNPX 2.5.0, which agreed almost perfectly with each other in range and only differed by 2% in the Bragg peak (BP) region. FLUKA was also used to calculate k{sub Q} factors for Markus chamber measurements as an improvement to the IAEA TRS-398 values in low-energy beams. FLUKA depth-dose simulations overestimate the BP height measured by ion chamber by about 10%, where the initial proton energy spread was estimated by fitting to the slope of the measured BP distal edge. Both GafChromic films showed an under-response in the BP compared to ion chamber; however, EBT exhibits this effect at lower energies than MD-V2-55. A possible reason for this is attributed to the shape and arrangement of the monomer particles being different in the active components of EBT and MD-V2-55. Relative effectiveness (RE) of both films is presented as functions of residual range R{sub res} in water and peak proton energy determined by FLUKA, with considerations for the spatial separation of the two active layers in each film. The proton energies at which RE reduces to 90% of maximum film response are 6.7 and 3.2 MeV for MD-V2-55 and EBT, respectively. Additionally, a beam quality correction factor (g{sub Q,Q{sub 0}}) is suggested for both GafChromic films, involving water-to-film stopping power ratios evaluated using ICRU recommendations, and a polymer yield factor G{sub Q{sub 0}}/G{sub Q}. RE in this work is equated to the reciprocal of the polymer yield factor. The calculated values of (s{sub w,film}){sub Q} /(s{sub w,film}){sub Q{sub 0}} are constant within 2.1% and 1.2% across the proton energy range of 1-300 MeV for EBT and MD-V2-55, respectively, so it is concluded that the polymer yield factor is the dominant factor

Energizing porters by proton-motive force.

Science.gov (United States)

Nelson, N

1994-11-01

It is generally accepted that the chemistry of water was the most crucial determinant in shaping life on earth. Among the more important chemical features of water is its dissociation into protons and hydroxyl ions. The presence of relatively high proton concentrations in the ambient solution resulted in the evolution of proton pumps during the dawn of life on earth. These proton pumps maintained neutral pH inside the cells and generated electrochemical gradients of protons (proton-motive force) across their membranes. The existence of proton-motive force enabled the evolution of porters driven by it that are most probably among the more primitive porters in the world. The directionality of the substrate transport by the porters could be to both sides of the membranes because they can serve as proton symporters or antiporters. One of the most important subjects of this meeting is the mechanism by which proton-motive and other ion-motive forces drive the transport processes through porters. Is there a common mechanism of action for all proton-driven porters? Is there some common partial reaction by which we can identify the way that porters are energized by proton-motive force? Is there a common coupling between proton movement and uptake or secretion of certain molecules? Even a partial answer to one of these questions would advance our knowledge... or confusion. As my mentor Efraim Racker used to say: 'If you are not totally confused you do not understand the issue'.

Field ion microscopy study of depleted zones in tungsten after proton irradiation

International Nuclear Information System (INIS)

Farnum, D.J.; Sommer, W.F.; Inal, O.T.; Yu, J.

1986-01-01

Depleted zones in tungsten, that resulted from medium-energy proton irradiations, were studied using the Field Ion Microscope (FIM). The shapes and sizes of depleted zones is an important aspect of basic radiation damage. These data can be compared to models that have been suggested as well as aid development of new models. These depleted volumes are of interest not only for an understanding of basic radiation effects, but also because they affect material properties and can act as nucleation sites for voids or gas bubbles. Depleted zones were produced in annealed tungsten wires by irradiation with 600 to 800 MeV protons at the Los Alamos Meson Physics Facility. The defects observed in the irradiated samples included vacancies, depleted zones, grain boundaries, and dislocations. Single vacancies were the most commonly observed defect. Of the samples ''imaged,'' over 50 depleted zones were found within the area of high resolution in the area between the prominent [112] poles in a [110] oriented sample. The number of layers photographed in each sample was dependent upon the initial shape of the tip and ranged from 60 to 200 [110] sequential layers

Composite proton exchange membrane based on sulfonated organic nanoparticles

Science.gov (United States)

Pitia, Emmanuel Sokiri

As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion

An in-beam PET system for monitoring ion-beam therapy: test on phantoms using clinical 62 MeV protons

Science.gov (United States)

Camarlinghi, N.; Sportelli, G.; Battistoni, G.; Belcari, N.; Cecchetti, M.; Cirrone, G. A. P.; Cuttone, G.; Ferretti, S.; Kraan, A.; Retico, A.; Romano, F.; Sala, P.; Straub, K.; Tramontana, A.; Del Guerra, A.; Rosso, V.

2014-04-01

Ion therapy allows the delivery of highly conformal dose taking advantage of the sharp depth-dose distribution at the Bragg-peak. However, patient positioning errors and anatomical uncertainties can cause dose distortions. To exploit the full potential of ion therapy, an accurate monitoring system of the ion range is needed. Among the proposed methods to monitor the ion range, Positron Emission Tomography (PET) has proven to be the most mature technique, allowing to reconstruct the β+ activity generated in the patient by the nuclear interaction of the ions, that can be acquired during or after the treatment. Taking advantages of the spatial correlation between positron emitters created along the ions path and the dose distribution, it is possible to reconstruct the ion range. Due to the high single rates generated during the beam extraction, the acquisition of the β+ activity is typically performed after the irradiation (cyclotron) or in between the synchrotron spills. Indeed the single photon rate can be one or more orders of magnitude higher than normal for cyclotron. Therefore, acquiring the activity during the beam irradiation requires a detector with a very short dead time. In this work, the DoPET detector, capable of sustaining the high event rate generated during the cyclotron irradiation, is presented. The capability of the system to acquire data during and after the irradiation will be demonstrated by showing the reconstructed activity for different PMMA irradiations performed using clinical dose rates and the 62 MeV proton beam at the CATANA-LNS-INFN. The reconstructed activity widths will be compared with the results obtained by simulating the proton beam interaction with the FLUKA Monte Carlo. The presented data are in good agreement with the FLUKA Monte Carlo.

An in-beam PET system for monitoring ion-beam therapy: test on phantoms using clinical 62 MeV protons

International Nuclear Information System (INIS)

Camarlinghi, N; Sportelli, G; Belcari, N; Cecchetti, M; Ferretti, S; Kraan, A; Retico, A; Straub, K; Guerra, A Del; Rosso, V; Battistoni, G; Sala, P; Cirrone, G A P; Cuttone, G; Romano, F; Tramontana, A

2014-01-01

Ion therapy allows the delivery of highly conformal dose taking advantage of the sharp depth-dose distribution at the Bragg-peak. However, patient positioning errors and anatomical uncertainties can cause dose distortions. To exploit the full potential of ion therapy, an accurate monitoring system of the ion range is needed. Among the proposed methods to monitor the ion range, Positron Emission Tomography (PET) has proven to be the most mature technique, allowing to reconstruct the β + activity generated in the patient by the nuclear interaction of the ions, that can be acquired during or after the treatment. Taking advantages of the spatial correlation between positron emitters created along the ions path and the dose distribution, it is possible to reconstruct the ion range. Due to the high single rates generated during the beam extraction, the acquisition of the β + activity is typically performed after the irradiation (cyclotron) or in between the synchrotron spills. Indeed the single photon rate can be one or more orders of magnitude higher than normal for cyclotron. Therefore, acquiring the activity during the beam irradiation requires a detector with a very short dead time. In this work, the DoPET detector, capable of sustaining the high event rate generated during the cyclotron irradiation, is presented. The capability of the system to acquire data during and after the irradiation will be demonstrated by showing the reconstructed activity for different PMMA irradiations performed using clinical dose rates and the 62 MeV proton beam at the CATANA-LNS-INFN. The reconstructed activity widths will be compared with the results obtained by simulating the proton beam interaction with the FLUKA Monte Carlo. The presented data are in good agreement with the FLUKA Monte Carlo

Incorporation of tantalum ions enhances the electrocatalytic activity of hexagonal WO3 nanowires for hydrogen evolution reaction

International Nuclear Information System (INIS)

Xie, Xiang; Mu, Wanjun; Li, Xingliang; Wei, Hongyuan; Jian, Yuan; Yu, Qianhong; Zhang, Rui; Lv, Kai; Tang, Hui; Luo, Shunzhong

2014-01-01

WO 3 has been identified as a promising candidate electrocatalyst for hydrogen evolution reaction (HER), because it can form a tungsten bronze (HxWO 3 ) which is highly electron and proton conducting. In this paper, we report that the electrocatalytic activity of WO 3 for HER can be enhanced by incorporation of tantalum ions (Ta 5+ ) into the lattice of WO 3 . The most active performance is achieved with the molar ratio of Ta/W being 0.01, which is two times more active than that of undoped WO 3 at an overpotential of -0.52 V. It is shown that incorporation of proper Ta 5+ into WO 3 can induce moderate defects and oxygen vacancies, as well as intercalate a higher amount of protons, which enhance the electron transfer and short the protons diffusion paths. These changes correlated positively with the enhanced catalytic HER activity. This study demonstrates, for the first time, that metal ions-doped WO 3 nanowires are promising electrocatalysts for HER

Electron stimulated desorption of positive and negative oxygen ions from YBa{sub 2}Cu{sub 3}O{sub 7} surfaces

Energy Technology Data Exchange (ETDEWEB)

Hoffman, A. [Technion-Israel Inst. of Tech., Haifa (Israel). Solid State Inst.; Moss, S.D.; Paterson, P.J.K. [Royal Melbourne Inst. of Tech., VIC (Australia); McCubbery, D. [La Trobe Univ., Bundoora, VIC (Australia); Petravic, M. [Australian National Univ., Canberra, ACT (Australia)

1996-12-31

The electron stimulated desorption (ESD) of positive and negative oxygen ion from superconducting YBa{sub 2}Cu{sub 3}O{sub 7} surfaces was studied. Based on ion desorption yield measurements as function of electron kinetic energy, primary excitations leading to positive and negative oxygen ion desorption are suggested. To the best of the authors` knowledge this is the first study on electron energy dependent ESD from YBa{sub 2}Cu{sub 3}O{sub 7} surfaces. The YBa{sub 2}Cu{sub 3}O{sub 7} samples were prepared from BaCO{sub 3}, Y{sub 2}O{sub 3} and CuO using standard high temperature sintering and annealing procedures. Slices 2 mm thick were cut and further annealed at 400 C in flowing oxygen for 24 hours prior to insertion into the ultrahigh vacuum (UHV) chamber for ESD. The near surface composition and chemical state of the annealed sample after exposure to air was examined by Auger and XPS analysis. These measurements suggest that the ESD experiments were performed on samples of similar near surface and bulk composition with some OH- chemisorbed groups and Cl surface contaminations and that negative and positive oxygen ion desorption may be initiated via a primary core level ionization. 10 refs., 3 figs.

Electron stimulated desorption of positive and negative oxygen ions from YBa{sub 2}Cu{sub 3}O{sub 7} surfaces

Energy Technology Data Exchange (ETDEWEB)

Hoffman, A [Technion-Israel Inst. of Tech., Haifa (Israel). Solid State Inst.; Moss, S D; Paterson, P J.K. [Royal Melbourne Inst. of Tech., VIC (Australia); McCubbery, D [La Trobe Univ., Bundoora, VIC (Australia); Petravic, M [Australian National Univ., Canberra, ACT (Australia)

1997-12-31

The electron stimulated desorption (ESD) of positive and negative oxygen ion from superconducting YBa{sub 2}Cu{sub 3}O{sub 7} surfaces was studied. Based on ion desorption yield measurements as function of electron kinetic energy, primary excitations leading to positive and negative oxygen ion desorption are suggested. To the best of the authors` knowledge this is the first study on electron energy dependent ESD from YBa{sub 2}Cu{sub 3}O{sub 7} surfaces. The YBa{sub 2}Cu{sub 3}O{sub 7} samples were prepared from BaCO{sub 3}, Y{sub 2}O{sub 3} and CuO using standard high temperature sintering and annealing procedures. Slices 2 mm thick were cut and further annealed at 400 C in flowing oxygen for 24 hours prior to insertion into the ultrahigh vacuum (UHV) chamber for ESD. The near surface composition and chemical state of the annealed sample after exposure to air was examined by Auger and XPS analysis. These measurements suggest that the ESD experiments were performed on samples of similar near surface and bulk composition with some OH- chemisorbed groups and Cl surface contaminations and that negative and positive oxygen ion desorption may be initiated via a primary core level ionization. 10 refs., 3 figs.

Distribution uniformity of laser-accelerated proton beams

Science.gov (United States)

Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

2017-09-01

Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

Radiosensitization of CHO cells by the combination of glutathione depletion and low concentrations of oxygen: The effect of different levels of GSH depletion

International Nuclear Information System (INIS)

Clark, E.P.; Epp, E.R.; Zachgo, E.A.; Biaglow, J.E.

1984-01-01

Recently, the authors have examined the effect of GSH depletion by BSO on CHO cells equilibrated with oxygen at various concentrations (0.05-4.0%) and irradiated with 50 kVp x-rays. This is of interest because of the uncertain radiosensitizing effect GSH depletion may have on cells equilibrated with low oxygen concentrations. GSH depletion (0.1 mM BSO/24 hrs reduced [GSH] ≅ 10% of control) enhanced the radiosensitizing action of moderate (0.4-4.0%) concentrations of oxygen, i.e., GSH depletion reduced the [O/sub 2/] necessary to achieve an equivalent ER by ≅ 2-3 fold. However, GSH depletion was much more effective as a rediosensitizer when cells were equilibrated with low (<0.4%) concentrations of oxygen, i.e., GSH depletion reduced the [O/sub 2/] necessary to achieve an equivalent ER by 8-10 fold. Furthermore, while the addition of exogenous 5 mM GSH restored the ER to that observed when GSH was not depleted, the intracellular [GSH] was not increased. The results of these studies carried out at different levels of GSH depletion are presented

Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides

KAUST Repository

Bi, Lei; Boulfrad, Samir; Traversa, Enrico

2014-01-01

Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides.

Science.gov (United States)

Bi, Lei; Boulfrad, Samir; Traversa, Enrico

2014-12-21

Energy crisis and environmental problems caused by the conventional combustion of fossil fuels boost the development of renewable and sustainable energies. H2 is regarded as a clean fuel for many applications and it also serves as an energy carrier for many renewable energy sources, such as solar and wind power. Among all the technologies for H2 production, steam electrolysis by solid oxide electrolysis cells (SOECs) has attracted much attention due to its high efficiency and low environmental impact, provided that the needed electrical power is generated from renewable sources. However, the deployment of SOECs based on conventional oxygen-ion conductors is limited by several issues, such as high operating temperature, hydrogen purification from water, and electrode stability. To avoid these problems, proton-conducting oxides are proposed as electrolyte materials for SOECs. This review paper provides a broad overview of the research progresses made for proton-conducting SOECs, summarizing the past work and finding the problems for the development of proton-conducting SOECs, as well as pointing out potential development directions.

Is the surface oxygen exchange rate linked to bulk ion diffusivity in mixed conducting Ruddlesden-Popper phases?

Science.gov (United States)

Tomkiewicz, Alex C; Tamimi, Mazin A; Huq, Ashfia; McIntosh, Steven

2015-01-01

The possible link between oxygen surface exchange rate and bulk oxygen anion diffusivity in mixed ionic and electronic conducting oxides is a topic of great interest and debate. While a large body of experimental evidence and theoretical analyses support a link, observed differences between bulk and surface composition of these materials are hard to reconcile with this observation. This is further compounded by potential problems with simultaneous measurement of both parameters. Here we utilize separate techniques, in situ neutron diffraction and pulsed isotopic surface exchange, to examine bulk ion mobility and surface oxygen exchange rates of three Ruddlesden-Popper phases, general form A(n-1)A(2)'B(n)O(3n+1), A(n-1)A(2)'B(n)X(3n+1); LaSrCo(0.5)Fe(0.5)O(4-δ) (n = 1), La(0.3)Sr(2.7)CoFeO(7-δ) (n = 2) and LaSr3Co(1.5)Fe(1.5)O(10-δ) (n = 3). These measurements are complemented by surface composition determination via high sensitivity-low energy ion scattering. We observe a correlation between bulk ion mobility and surface exchange rate between materials. The surface exchange rates vary by more than one order of magnitude with high anion mobility in the bulk of an oxygen vacancy-rich n = 2 Ruddlesden-Popper material correlating with rapid oxygen exchange. This is in contrast with the similar surface exchange rates which we may expect due to similar surface compositions across all three samples. We conclude that experimental limitations lead to inherent convolution of surface and bulk rates, and that surface exchange steps are not likely to be rate limiting in oxygen incorporation.

An ab initio molecular dynamics study

Indian Academy of Sciences (India)

. [9–12]. ... The average values of the coordination numbers of the hydrated proton are also ... We equilibrated the systems for about 10 ps at 300K. 764 ... hydronium ion changing from 1 to 16 and then to 8 during the 10ps production run of the ...

Study of the energetic proton production in relativistic heavy ions Ne + nuclei collisions, using Diogene detector. Hadronic matter temperature

International Nuclear Information System (INIS)

Rahmani, A.

1988-12-01

The study of the proton's production differential cross sections, in the collision of relativistic heavy ions, allows to obtain the nuclear-matter temperature and gives information about the nucleons large burst pulses in the nucleus. The chosen thermodynamic model is a generalized approach of the R. Hagedorn model, applied to heavy ions collisions: the nuclear matter is divided in volume elements δV assumed to be in thermal and chemical equilibrium and emitting particles and fragments isotropically, inside their own system. The applied nuclear-matter velocity distribution depended only on the impact parameter and on the relationship between the chemical potential and the temperature. The predictions of this thermodynamic model were compared to the Saturne experimental results, using Diogene detector. The obtained temperature values are similar to those given by D. Hahn and H. Stoker. The proton production cross sections were measured for backward emitting angles. A relationship between the cross sections and the burst pulse distribution in the nuclei was settled [fr

Magnetospheric Multiscale (MMS) Observations of Energetic Ion Response to Magnetotail Dipolarization Events

Science.gov (United States)

Cohen, I. J.; Mauk, B.; Anderson, B. J.; Sitnov, M. I.; Motoba, T.; Ohtani, S.; Gkioulidou, M.; Fuselier, S. A.; Giles, B. L.; Strangeway, R. J.; Torbert, R. B.; Burch, J. L.

2017-12-01

Observations from the Energetic Ion Spectrometer (EIS) instruments aboard MMS have shown angular (pitch, elevation, azimuthal) asymmetries of energetic (>10s of keV) ions corresponding to dipolarization events in the near-Earth and distant magnetotail. In particular, EIS distinguishes the species composition of these ions (protons, helium, oxygen) and reveals apparent species-based differences in their response. This study presents analysis of the dynamic injection and mass-dependent response of energetic ions that likely result from the kinetic response of the ions to the time-varying electric and magnetic fields associated with injection process. Analysis is focused on discriminating between truly kinetic responses to the dynamics and the features that arise from large gyro-radii particles in the vicinity of strong spatial gradients. The study will focus on EIS measurements and include supplementary data from the FIELDS, FPI, and HPCA instruments.

Measurement of plant and soil water isotope composition by direct equilibration methods

Science.gov (United States)

Scrimgeour, C. M.

1995-11-01

Water contained in plant and soil samples can be analysed for 2H and 18O content by direct equilibration while contained within the sample matrix. Methods for this are described and compared with the commonly used azeotropic distillation of samples before isotope analysis. For δ18O, direct equilibration with CO 2 gives results in good agreement with azeotropic distillation, i.e. within 0.5%o at natural abundance. Direct equilibration is a practical method for individual twig samples containing less than 0.5 ml of water, and offers significant operator time savings compared with azeotropic distillation. Batches of up to 100 samples can be prepared in less time than required for a single azeotropic distillation, and analysis by automated continuous-flow isotope ratio mass spectrometry after equilibration for 3 days again requires a minimum of operator time. Complete equilibration of plant water with H 2 for δ2H measurement occurs only after the plant material has been heated to 100°C under vacuum. The method described here is barely precise enough for natural abundance measurements ( δ 2H ± 15‰ ) but is well suited to field tracer studies with deuterium oxide.

Chemical freeze-out study in proton-proton collisions at RHIC and LHC energies

International Nuclear Information System (INIS)

Das, Sabita; Mishra, Debadeepti; Mohanty, Bedangadas; Chatterjee, Sandeep

2016-01-01

Particle multiplicities measured at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) facilities can be used to understand the chemical freeze-out dynamics. At chemical freeze-out (CFO), inelastic collisions cease and the freeze-out parameters can be determined using measured particle multiplicities within the framework of a statistical model. The statistical model has proven to be quite successful in describing the particle production from elementary p-p and e"+e"- collisions up to heavy-ion collisions. It helps to do a systematic study of the centrality and energy dependence of freeze-out parameters in heavy-ion collisions from lower SPS to higher LHC energies. The new data at LHC along with the RHIC data can be used to do such a systematic study in proton-proton collisions

Can membrane-bound carotenoid pigment zeaxanthin carry out a transmembrane proton transfer?

Science.gov (United States)

Kupisz, Kamila; Sujak, Agnieszka; Patyra, Magdalena; Trebacz, Kazimierz; Gruszecki, Wiesław I

2008-10-01

Polar carotenoid pigment zeaxanthin (beta,beta-carotene-3,3'-diol) incorporated into planar lipid membranes formed with diphytanoyl phosphatidylcholine increases the specific electric resistance of the membrane from ca. 4 to 13 x 10(7) Omega cm2 (at 5 mol% zeaxanthin with respect to lipid). Such an observation is consistent with the well known effect of polar carotenoids in decreasing fluidity and structural stabilization of lipid bilayers. Zeaxanthin incorporated into the lipid membrane at 1 mol% has very small effect on the overall membrane resistance but facilitates equilibration of the transmembrane proton gradient, as demonstrated with the application of the H+-sensitive antimony electrodes. Relatively low changes in the electrical potential suggest that the equilibration process may be associated with a symport/antiport activity or with a transmembrane transfer of the molecules of acid. UV-Vis linear dichroism analysis of multibilayer formed with the same lipid-carotenoid system shows that the transition dipole moment of the pigment molecules forms a mean angle of 21 degrees with respect to the axis normal to the plane of the membrane. This means that zeaxanthin spans the membrane and tends to have its two hydroxyl groups anchored in the opposite polar zones of the membrane. Detailed FTIR analysis of beta-carotene and zeaxanthin indicates that the polyene chain of carotenoids is able to form weak hydrogen bonds with water molecules. Possible molecular mechanisms responsible for proton transport by polyenes are discussed, including direct involvement of the polyene chain in proton transfer and indirect effect of the pigment on physical properties of the membrane.

Viscosity of bound water and model of proton relaxation in fine-dispersed substances at the presence of adsorbed paramagnetic ions

International Nuclear Information System (INIS)

Fedodeev, V.I.

1975-01-01

A microviscosity model of proton relaxation in pure liquids and in solutions of paramagnetic ions is examined. It is shown that the influence of adsorbed paramagnetic centers on proton relaxation in finely dispersed substances is significantly weaker than in solutions. A 'two-phase' relaxation model is used in determining the parameters of the bound liquid (water) using nuclear magnetic resonance data. The relations obtained with the model are used to compute the viscosity of water in clay. The value is of the same order of magnitude as that obtained by other methods

Viscosity of bound water and model of proton relaxation in fine-dispersed substances at the presence of adsorbed paramagnetic ions

Energy Technology Data Exchange (ETDEWEB)

Fedodeev, V I

1975-09-01

A microviscosity model of proton relaxation in pure liquids and in solutions of paramagnetic ions is examined. It is shown that the influence of adsorbed paramagnetic centers on proton relaxation in finely dispersed substances is significantly weaker than in solutions. A 'two-phase' relaxation model is used in determining the parameters of the bound liquid (water) using nuclear magnetic resonance data. The relations obtained with the model are used to compute the viscosity of water in clay. The value is of the same order of magnitude as that obtained by other methods.

Monitoring and measurement of oxygen concentrations in liquid sodium

International Nuclear Information System (INIS)

Smith, D.L.

1976-01-01

The measurement of oxygen concentrations in sodium at levels of interest for LMFBR applications is reviewed. Additional data are presented to support the validity of the vanadium-equilibration method as a reference for determination of oxygen concentrations in sodium at levels equal to or less than 15 ppM. Operating experience with electrochemical oxygen meters that have a thoria-yttria electrolyte and a Na--Na 2 O reference electrode is described. Meter lifetimes in excess of one year have generally been achieved for operating temperatures of 352 and 402 0 C, and fairly stable emfs have been observed for periods of several months. 7 fig, 21 references

Charge steering of laser plasma accelerated fast ions in a liquid spray — creation of MeV negative ion and neutral atom beams

International Nuclear Information System (INIS)

Schnürer, M.; Abicht, F.; Priebe, G.; Braenzel, J.; Prasad, R.; Borghesi, M.; Andreev, A.; Nickles, P. V.; Jequier, S.; Tikhonchuk, V.; Ter-Avetisyan, S.

2013-01-01

The scenario of “electron capture and loss” has been recently proposed for the formation of negative ion and neutral atom beams with up to MeV kinetic energy [S. Ter-Avetisyan, et al., Appl. Phys. Lett. 99, 051501 (2011)]. Validation of these processes and of their generic nature is here provided in experiments where the ion source and the interaction medium have been spatially separated. Fast positive ions accelerated from a laser plasma source are sent through a cold spray where their charge is changed. Such formed neutral atom or negative ion has nearly the same momentum as the original positive ion. Experiments are released for protons, carbon, and oxygen ions and corresponding beams of negative ions and neutral atoms have been obtained. The electron capture and loss phenomenon is confirmed to be the origin of the negative ion and neutral atom beams. The equilibrium ratios of different charge components and cross sections have been measured. Our method is general and allows the creation of beams of neutral atoms and negative ions for different species which inherit the characteristics of the positive ion source

Proton-transfer reactions in ionized gases

International Nuclear Information System (INIS)

Stiller, W.; Schmidt, R.; Schuster, R.

1985-01-01

Ion-molecule reactions play an important role in various radiolytic processes, e.g. gas-pulse radiolysis, environmental research. For a discussion of mechanisms rate coefficients have to be assessed. Here gas-phase rate coefficients of ion-(polar) molecule reactions are calculated using the ideas of interaction potentials, reactive cross-sections and distribution functions of the translational energies of both the reactants (ions I, molecules M). The starting point of our approach, directed especially to gas-phase proton-transfer reactions, is the idea that the rate coefficient k can be calculated as an ion-molecule capture-rate coefficient multiplied by a 'steric factor' representing the probability for proton transfer. Mutual capture of the reaction partners within a possible reaction zone is caused by the physical interaction between an ion and a polar molecule. A model is discussed. Results are presented. (author)

MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations

Energy Technology Data Exchange (ETDEWEB)

Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Jeynes, J.C.G.; Merchant, M.J.; Kirkby, K.; Kirkby, N. [Surrey Ion Beam Center, Faculty of Engineering and Physical Science, University of Surrey, Guildford Surrey, GU2 7XH (United Kingdom); Thopan, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

2013-07-15

Highlights: •Recently completed nanobeam at the Surrey Ion Beam Centre was used. •3.8-MeV single and broad proton beams irradiated Chinese hamster cells. •Cell survival curves were measured and compared with 300-kV X-ray irradiation. •Single ion irradiation had a lower survival part at ultra-low dose. •It implies hypersensitivity, bystander effect and cell cycle phase of cell death. -- Abstract: As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.