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1

Pathway and energetics of xenon migration in uranium dioxide  

NASA Astrophysics Data System (ADS)

Using a combination of density functional theory (DFT), classical potentials, molecular dynamics, and nudged elastic band (NEB) calculations, we explore the diffusion of xenon in uranium dioxide (UO2). We compare migration barriers of empirical potentials with DFT by performing NEB calculations and subsequently we use the DFT-validated empirical potentials to calculate vacancy clusters, with and without xenon, to determine the migration path and barrier of xenon in bulk UO2. We find the following: (i) Two empirical potentials out of four tested agree qualitatively with DFT derived energetics for Schottky defect migration; (ii) through the use of molecular dynamics with empirical potentials, we have found a path for the diffusion of xenon-tetravacancy clusters (Xe+2VU+2VO); (iii) this path has an energy barrier significantly lower than previously reported paths by nearly 1 eV; (iv) we examine the physical contributions to the migration pathway and find the barrier is largely electrostatic and that xenon contributes very little to the barrier height; (v) once a uranium vacancy attaches to a xenon-Schottky defect, the resulting xenon-tetravacancy cluster is strongly bound; and (vi) as xenon in a tetravacancy, a xenon-double Schottky defect can diffuse in a concerted manor with a comparable barrier to xenon in a tetravacancy, but two of the oxygen vacancies are only weakly bound to the defect.

Thompson, Alexander E.; Wolverton, C.

2013-03-01

2

Measurement of xenon in uranium dioxide (UO 2) with SIMS  

Microsoft Academic Search

The detection of rare gases in irradiated nuclear fuel is a great challenge in nuclear industry. Although gas measurement is not usual using SIMS technique, we show that xenon can actually be measured in an implanted UO2 sample by SIMS. The physical mechanisms of xenon detection are discussed and a method is proposed for xenon quantitative measurement.

L. Desgranges; B. Pasquet

2004-01-01

3

XENON  

Microsoft Academic Search

The XENON experiment aims at the direct detection of dark matter in the form of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off Xenon nuclei. With 1 ton of LXe distributed in ten identical modules, the proposed XENON1T experiment will achieve a sensitivity more than a factor of thousand beyond current limits.The detectors are time projection chambers operated

E. Aprile; K.-L. Giboni; M. E. Monzani; G. Plante; M. Yamashita; R. J. Gaitskell; S. Fiorucci; P. Sorensen; L. Deviveiros; A. Bernstein; N. Madden; C. Winant; T. Shutt; J. Kwong; A. Bolozdynya; E. Dahl; U. Oberlack; P. Shagin; R. Gomez; D. McKinsey; A. Manzur; R. Hasty; K. Ni; F. Arneodo; A. Ferella; L. Baudis; J. Angle; J. Orboeck; A. Manalaysay; J. A. M. Lopes; L. Coelho; L. Fernandes; J. Santos

2007-01-01

4

Comment on ``Interplay of defect cluster and the stability of xenon in uranium dioxide from density functional calculations''  

NASA Astrophysics Data System (ADS)

Geng [H. Y. Geng, Y. Chen, Y. Kaneta, M. Kinoshita, and Q. Wu, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.82.094106 82, 094106 (2010)] recently reported DFT+U calculations of xenon behavior in uranium dioxide UO2. One of the main conclusions of their work is that the quasiannealing (QA) procedure allowed them to avoid metastable states created by the DFT+U approximation. However, based on a comparison of total energies, they stated that an incomplete implementation of occupation matrix control (OMC) had been done in our previous work [B. Dorado, G. Jomard, M. Freyss, and M. Bertolus, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.82.035114 82, 035114 (2010)] and that we failed to reach the ground state of the perfect UO2 fluorite structure. In this Comment, we show that the discrepancy they observed does not stem from an incomplete implementation of OMC, but from the calculation of the compensation charge used in the projector augmented-wave formalism.

Dorado, Boris; Amadon, Bernard; Jomard, Grald; Freyss, Michel; Bertolus, Marjorie

2011-09-01

5

Dynamical mean-field theory for transition metal dioxide molecules  

NASA Astrophysics Data System (ADS)

The utility of the dynamical mean-field approximation in quantum chemistry is investigated in the context of transition metal dioxide molecules including TiO2 and CrO2. The choice of correlated orbitals and correlations to treat dynamically is discussed. The dynamical mean field solutions are compared to state of the art quantum chemical calculations. The dynamical mean-field method is found to capture about 50% of the total correlation energy, and to produce very good results for the d-level occupancies and magnetic moments. We also present the excitation spectrum in these molecules which is inaccessible in many wave-function based methods. Conceptual and technical difficulties will be outlined and discussed.

Lin, Nan; Zgid, Dominika; Marianetti, Chris; Reichman, David; Millis, Andrew

2012-02-01

6

Response of ionization chambers filled with liquid xenon doped with organic molecules to gamma rays  

NASA Astrophysics Data System (ADS)

The charge collection and energy resolution in liquid rare gas ionization chambers can be improved by doping the liquid with photoionization molecules. We have observed the improvement in liquid Xe doped with triethylamine (TEA). The improvement is remarkable especially at a low electric field region. This effect is used to develop gamma-ray detectors with good energy resolution as well as high detection efficiency for gamma rays.

Masuda, Kimiaki

1992-12-01

7

A plan for directional dark matter sensitivity in high-pressure xenon detectors through the addition of wavelength shifting gaseous molecules  

NASA Astrophysics Data System (ADS)

Xenon is an especially attractive candidate for both direct WIMP and 0??? decay searches. Although the current trend has exploited the liquid phase, the gas phase xenon offers remarkable performance advantages for: energy resolution, topology visualization, and discrimination between electron and nuclear recoils. The NEXT-100 experiment, now under construction in the Canfranc Underground Laboratory, Spain, will operate at ~ 15 bars with 100 kg of 136Xe for the 0??? decay search. We will describe recent results with small prototypes, indicating that NEXT-100 can provide about 0.5% FWHM energy resolution at the decay's Q value (2457.83 keV), as well as rejection of ?-rays with topological cuts. However, sensitivity goals for WIMP dark matter and 0??? decay searches indicate the probable need for ton-scale active masses. NEXT-100 provides the springboard to reach this scale with xenon gas. We describe a scenario for performing both searches in a single, high-pressure, ton-scale xenon gas detector, without significant compromise to either. In addition, even in a single ton-scale, high-pressure xenon gas TPC, an intrinsic sensitivity to the nuclear recoil direction may exist. This plausibly offers an advance of more than two orders of magnitude relative to current low-pressure TPC concepts. We argue that, in an era of deepening fiscal austerity, such a dual-purpose detector may be possible at acceptable cost, within the time frame of interest, and deserves our collective attention.

Gehman, V. M.; Goldschmidt, A.; Nygren, D.; Oliveira, C. A. B.; Renner, J.

2013-10-01

8

Core localization and {sigma}* delocalization in the O 1s core-excited sulfur dioxide molecule  

SciTech Connect

Electron-ion-ion coincidence measurements of sulfur dioxide at discrete resonances near the O 1s ionization edge are reported. The spectra are analyzed using a model based upon molecular symmetry and on the geometry of the molecule. We find clear evidence for molecular alignment that can be ascribed to symmetry properties of the ground and core-excited states. Configuration interaction (CI) calculations indicate geometry changes in accord with the measured spectra. For the SO{sub 2} molecule, however, we find that the localized core hole does not produce measurable evidence for valence localization, since the transition dipole moment is not parallel to a breaking {sigma}* O-S bond, in contrast to the case of ozone. The dissociation behavior based upon the CI calculations using symmetry-broken orbitals while fixing a localized core-hole site is found to be nearly equivalent to that using symmetry-adapted orbitals. This implies that the core-localization effect is not strong enough to localize the {sigma}* valence orbital.

Lindgren, Andreas; Kivimaeki, Antti; Sorensen, Stacey L. [Department of Synchrotron Radiation Research, Institute of Physics, University of Lund, S-221 00 Lund (Sweden); Kosugi, Nobuhiro [UVSOR, Institute for Molecular Science (IMS), Myodaiji, Okazaki 444-8585 (Japan); Gisselbrecht, Mathieu [MAX-Lab, Box 118, University of Lund, S-221 00 Lund (Sweden); Burmeister, Florian [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Naves de Brito, Arnaldo [Laboratorio Nacional de Luz Sincrotron (LNLS), Box 6192, 13084-971 Campinas SP (Brazil)

2008-03-21

9

HXeOBr in a xenon matrix  

SciTech Connect

We report on a new noble-gas molecule HXeOBr prepared in a low-temperature xenon matrix from the HBr and N{sub 2}O precursors by UV photolysis and thermal annealing. This molecule is assigned with the help of deuteration experiments and ab initio calculations including anharmonic methods. The H-Xe stretching frequency of HXeOBr is observed at 1634 cm{sup -1}, which is larger by 56 cm{sup -1} than the frequency of HXeOH identified previously. The experiments show a higher thermal stability of HXeOBr molecules in a xenon matrix compared to HXeOH.

Khriachtchev, Leonid; Tapio, Salla; Domanskaya, Alexandra V.; Raesaenen, Markku [Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 (Finland); Isokoski, Karoliina [Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Lundell, Jan [Department of Chemistry, University of Jyvaeskylae, P.O. Box 35, FIN-40014 Jyvaeskylae (Finland)

2011-03-28

10

Magnetism-tunable oligoacene dioxide diradicals: promising magnetic oligoacene-like molecules.  

PubMed

Graphene oxide has attracted intense research interest recently because the graphene oxide synthesis route, as a promising alternative for cost-effective mass production of graphene, has been explored. To further study the oxidation process and possible mechanism and to explore applicability of the oxidized products, we have performed a computational study on three series of oligoacene dioxides, focusing on their structures and electronic properties. Taking 1,5-dioxidized naphthalene as a starting point, three series of oligoacene dioxides are considered as follows: 1) middle insertion by 1-2 benzene rings; 2) single-side expansion using 1-2 benzene rings; 3) double-side expansion using two benzene rings. On the basis of density functional theory and complete active space self-consistent field (CASSCF) calculations, we reveal that oligoacene dioxides in the middle insertion series have a triplet ground state, whereas those in the single-side expansion series and the double-side expansion series have open-shell broken-symmetry singlet diradical ground states except for their common origin naphthalene-1,5-dioxide whose ground state is triplet and which is also viewed as the origin of the middle insertion series. Magnetic coupling interactions of these oligoacene dioxides are also determined. This work should help people toward an atomistic understanding of the electronic structures and properties of possible intermediates or products and even the oxidation mechanism of graphene sheets, and provides a reasonable strategy of designing novel graphene-oxide-based magnetic materials. PMID:23139198

Yang, Hongfang; Han, Li; Zhao, Jing; Song, Xinyu; Song, Qisheng; Bu, Yuxiang

2012-11-08

11

Crystalline Xenon Particle Detector  

Microsoft Academic Search

The sensitivity necessary to measure single photon electrons may be achieved through ionization produced in a crystalline xenon based particle detector. Following crystal formation and the application of an electric field, the ionization drifts to the surface and can be extracted from the solid xenon. Quantification of the ions is accomplished by utilizing a silicon PIN diode scintillation detector with

J. A. Maxin; R. Blessitt; J. Gao; J. Miller; G. Salinas; J. Seifert; J. T. White

2004-01-01

12

The XENON Dark Matter Search  

Microsoft Academic Search

The XENON experiment will search for Weakly Interacting Massive Particles (WIMPS), a leading candidate for the dark matter content of the Universe. The XENON detector uses the simultaneous measurement of ionization and scintillation in liquid xenon to distinguish between nuclear recoils and background electronic interactions. Ionization electrons are extracted into the xenon vapor where they produce a large proportional scintillation

D. N. McKinsey

2006-01-01

13

Nanoporosity of an organo-clay shown by hyperpolarized xenon and 2D NMR spectroscopy.  

PubMed

Interlayer nanoporosity of hectorite pillared by tetraethylammonium ions is explored by hyperpolarized xenon NMR and relevant gases such as carbon dioxide revealing the adsorption capacity of the open galleries. PMID:16767236

Sozzani, Piero; Bracco, Silvia; Comotti, Angiolina; Mauri, Michele; Simonutti, Roberto; Valsesia, Patrizia

2006-03-06

14

Xenon Diffusivity in Thoria-Urania Fuel  

SciTech Connect

Postirradiation annealing tests were performed to obtain the {sup 133}Xe diffusion coefficients in uranium dioxide (UO{sub 2}) and mixed thorium-uranium dioxide [(Th-U)O{sub 2}] fuels. Specimens were a single-grained UO{sub 2}, a polycrystalline UO{sub 2}, and a polycrystalline (Th-U)O{sub 2}. The (Th-U)O{sub 2} specimen was a mixture of 35% ThO{sub 2} and 65% UO{sub 2}. Each 300-mg specimen was irradiated to a burnup of 0.1 MWd/t U. Postirradiation annealing tests were performed at 1400, 1500, and 1600 deg. C, continuously. The xenon diffusion coefficients for the nearly stoichiometric single-grained UO{sub 2} agree well with the data of others. The xenon diffusion coefficients in the polycrystalline (Th-U)O{sub 2} are approximately one order lower than those in the polycrystalline UO{sub 2}. The xenon diffusion coefficient in the (Th-U)O{sub 2} increases with the increasing oxygen potential of the ambient gas.

Kim, Heemoon [Korea Atomic Energy Research Institute (Korea, Republic of); Park, Kwangheon [Kyunghee University (Korea, Republic of); Kim, Bong Goo [Korea Atomic Energy Research Institute (Korea, Republic of); Choo, Yong Sun [Korea Atomic Energy Research Institute (Korea, Republic of); Kim, Keon Sik [Korea Atomic Energy Research Institute (Korea, Republic of); Song, Kun Woo [Korea Atomic Energy Research Institute (Korea, Republic of); Hong, Kwon Pyo [Korea Atomic Energy Research Institute (Korea, Republic of); Kang, Young Hwan [Korea Atomic Energy Research Institute (Korea, Republic of); Ho, Kwangil [Suwon University (Korea, Republic of)

2004-07-15

15

Gas-phase silicon micromachining with xenon difluoride  

Microsoft Academic Search

Xenon difluoride is a gas phase, room temperature, isotropic silicon etchant with extremely high selectivity to many materials commonly used in microelectromechancial systems, including photoresists, aluminum, and silicon dioxide. Using a simple vacuum system, the effects of etch aperture and loading were explored for etches between 10 and 200 micrometers . Etch rates as high as 40 micrometers \\/minute were

Floy I. Chang; Richard Yeh; Gisela Lin; Patrick B. Chu; Eric G. Hoffman; Ezekiel J. Kruglick; Kristofer S. Pister; Michael H. Hecht

1995-01-01

16

High resolution infrared spectra of a carbon dioxide molecule solvated with helium atoms  

NASA Astrophysics Data System (ADS)

Infrared spectra of HeN-CO2 clusters with N up to about 20 have been studied in the region of the CO2 ?3 fundamental band (~2350 cm-1) using a tunable diode laser spectrometer and pulsed supersonic jet source with cooled (>-150 C) pinhole or slit nozzles and high backing pressures (<40 atm). Compared to previous studies of HeN-OCS and -N2O clusters, the higher symmetry of CO2 results in simpler spectra but less information content. Discrete rotation-vibration transitions have been assigned for N=3-17, and their analysis yields the variation of the vibrational band origin and B rotational constant over this size range. The band origin variation is similar to HeN-OCS, with an initial blueshift up to N=5, followed by a monotonic redshift, consistent with a model where the first five He atoms fill a ring around the equator of the molecule, forcing subsequent He atom density to locate closer to the ends. The B value initially drops as expected for a normal molecule, reaching a minimum for N=5. Its subsequent rise for N=6 to 11 can be interpreted as the transition from a normal (though floppy) molecule to a quantum solvation regime, where the CO2 molecule starts to rotate separately from the He atoms. For N>13, the B value becomes approximately constant with a value about 17% larger than that measured in much larger helium nanodroplets.

Tang, Jian; McKellar, A. R. W.

2004-07-01

17

Strong anisotropy in the proton emission following fragmentation of H2O molecules by impact with slow, highly charged Xenon ions  

Microsoft Academic Search

We measured the energy and angular distribution of ionic fragments produced by the interaction of 1-220 keV Xe22+ ions with water molecules. The measured distributions strongly depend on the projectile charge state and energy, as seen from the comparison of the results with previously published data for 5 keV He2+, and 2 and 90 keV Ne(3-9)+ ions. A significant forward-backward

Z. D. Pesic; R. Hellhammer; B. Sulik; N. Stolterfoht

2009-01-01

18

Diffusive nature of xenon anesthetic changes properties of a lipid bilayer: molecular dynamics simulations.  

PubMed

Effects of general anesthesia can be controllable by the ambient pressure. We perform molecular dynamics simulations for a 1-palmitoyl-2-oleoyl phosphatidylethanolamine lipid bilayer with or without xenon molecules by changing the pressure to elucidate the mechanism of the pressure reversal of general anesthesia. According to the diffusive nature of xenon molecules in the lipid bilayer, a decrease in the orientational order of the lipid tails, an increase in the area and volume per lipid molecule, and an increase in the diffusivity of lipid molecules are observed. We show that the properties of the lipid bilayer with xenon molecules at high pressure come close to those without xenon molecules at 0.1 MPa. Furthermore, we find that xenon molecules are concentrated in the middle of the lipid bilayer at high pressures by the pushing effect and that the diffusivity of xenon molecules is suppressed. These results suggest that the pressure reversal originates from a jamming and suppression of the diffusivity of xenon molecules in lipid bilayers. PMID:22715916

Yamamoto, Eiji; Akimoto, Takuma; Shimizu, Hiroyuki; Hirano, Yoshinori; Yasui, Masato; Yasuoka, Kenji

2012-07-11

19

Interaction of nitrogen dioxide molecules with the surface of silicon nanocrystals in porous silicon layers  

Microsoft Academic Search

The methods of infrared absorption spectroscopy and electron paramagnetic resonance are used for studying the effect of adsorption\\u000a of NO2 molecules, which are strong acceptors of electrons, on the electronic and optical properties of silicon nanocrystals in mesoporous\\u000a silicon layers. It is found that the concentration of free charge carriers (holes) in silicon nanocrystals, which exhibits\\u000a a nonmonotonic dependence on

E. A. Konstantinova; L. A. Osminkina; K. S. Sharov; E. V. Kurepina; P. K. Kashkarov; V. Yu. Timoshenko

2004-01-01

20

Separation and purification of xenon  

DOEpatents

Xenon is separated from a mixture of xenon and krypton by extractive distillation using carbon tetrafluoride as the partitioning agent. Krypton is flushed out of the distillation column with CF.sub.4 in the gaseous overhead stream while purified xenon is recovered from the liquid bottoms. The distillation is conducted at about atmospheric pressure or at subatmospheric pressure.

Schlea, deceased, Carl Solomon (LATE OF Aiken, SC)

1978-03-14

21

A Molecular Dynamics Study on the Confinement of Carbon Dioxide Molecules in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The influence of atmospheric carbon dioxide (CO2) concentration on global warming is considered as one of the primary environmental issues of the past two decades. The main source of CO2 emission is human activity, such as the use of fossil fuels in transportation and industrial plants. Following the release of Kyoto Protocol in 1997, effective ways of controlling CO2 emissions received much attention. As a result, various materials such as activated carbon, zeolites, and carbon nanotubes (CNTs) were investigated for their CO2 adsorbing properties. CNTs were reported to have CO2 adsorption capability twice that of activated carbon, hence they received the most attention. In the current study, single walled carbon nanotubes (SWNTs) were used as one dimensional nanoporous materials and their CO2 adsorption capacity was analyzed with Molecular Dynamics simulations. Results indicated that SWNTs are excellent CO2 adsorbers and their effectiveness increase at low CO2 concentrations. In addition, we showed that by varying temperature, CO2 can be removed from the SWNTs, providing a simple method to reuse SWNTs.

Lazor, Meagan; Rende, Deniz; Baysal, Nihat; Ozisik, Rahmi

2012-02-01

22

Thin uranium dioxide films with embedded xenon  

NASA Astrophysics Data System (ADS)

The ion beam assisted deposition (IBAD) method was applied as a means to incorporate Xe atoms into UO2 films to fabricate reference samples that are representative of an irradiated nuclear fuel without an actual reactor irradiation. The characterization of Xe content and the films microstructure was performed using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDXS). A set of UO2 films with excellent control of Xe content ranging from 1.0 to 4.0 at.% was fabricated. The thin UO2 films deposited on single crystalline 4H-SiC substrates were found to be composed primarily of randomly oriented nanocrystalline grains and a small fraction of amorphous material. TEM analysis detected no Xe-filled bubbles at a scale of 2.5 nm or larger.

Usov, I. O.; Dickerson, R. M.; Dickerson, P. O.; Hawley, M. E.; Byler, D. D.; McClellan, K. J.

2013-06-01

23

Titantium Dioxide Nanoparticles Assembled by DNA Molecules Hybridization and Loading of DNA Interacting Proteins  

PubMed Central

This work demonstrates the assembly of TiO2 nanoparticles with attached DNA oligonucleotides into a 3D mesh structure by allowing base pairing between oligonucleotides. A change of the ratio of DNA oligonucleotide molecules and TiO2 nanoparticles regulates the size of the mesh as characterized by UV-visible light spectra, transmission electron microscopy and atomic force microscopy images. This type of 3D mesh, based on TiO2-DNA oligonucleotide nanoconjugates, can be used for studies of nanoparticle assemblies in material science, energy science related to dye-sensitized solar cells, environmental science as well as characterization of DNA interacting proteins in the field of molecular biology. As an example of one such assembly, proliferating cell nuclear antigen protein (PCNA) was cloned, its activity verified, and the protein was purified, loaded onto double strand DNA oligonucleotide-TiO2 nanoconjugates, and imaged by atomic force microscopy. This type of approach may be used to sample and perhaps quantify and/or extract specific cellular proteins from complex cellular protein mixtures affinity based on their affinity for chosen DNA segments assembled into the 3D matrix.

WU, Aiguo; Paunesku, Tatjana; Brown, Eric M. B.; Babbo, Angela; Cruz, Cecille; Aslam, Mohamed; Dravid, Vinayak; Woloschak, Gayle E

2009-01-01

24

Electrochemical Reduction of Carbon Dioxide on Pyrite as a Pathway for Abiogenic Formation of Organic Molecules  

NASA Astrophysics Data System (ADS)

A wide spectrum of electrode potentials of minerals that compose sulfide ores enables the latter, when in contact with hydrothermal solutions, to form galvanic pairs with cathode potentials sufficient for electrochemical reduction of CO2. The experiments performed demonstrated the increase of cathode current on the rotating pyrite disc electrode in a range of potentials more negative than -800 mV in presence of CO2. In high-pressure experiments performed in a specially designed electrochemical cell equipped with a pyrite cathode and placed into autoclave, accumulation of formate was demonstrated after 24 hr passing of CO2 (50 atm, room temperature) through electrolyte solution. The formation of this product started on increasing the cathode potential to -800 mV (with respect to saturated silver chloride electrode). The yield grew exponentially upon cathode potential increase up to -1200 mV. The maximum current efficiency (0.12%) was registered at cathode potentials of about -1000 mV. No formate production was registered under normal atmospheric pressure and in the absence of imposed cathode potential. Neither in experiments, nor in control was formaldehyde found. It is proposed that the electrochemical reduction of CO2 takes part in the formation of organic molecules in hydrothermal solutions accompanying sulfide ore deposits and in `black smokers' on the ocean floor.

Vladimirov, M. G.; Ryzhkov, Y. F.; Alekseev, V. A.; Bogdanovskaya, V. A.; Otroshchenko, V. A.; Kritsky, M. S.

2004-08-01

25

Vibrational Relaxation of Ground-State Oxygen Molecules With Atomic Oxygen and Carbon Dioxide  

NASA Astrophysics Data System (ADS)

Vertical water vapor profiles are key to understanding the composition and energy budget in the mesosphere and lower thermosphere (MLT). The SABER instrument onboard NASA's TIMED satellite measures such profiles by detecting H2O(?2) emission in the 6.8 ?m region. Collisional deactivation of vibrationally excited O2, O2(X3?-g, ? = 1) + H2O ? O2(X3?-g, ? = 0) + H2O(?2), is an important source of H2O(?2). A recent study has identified two other processes involving excited O2 that control H2O(?2) population in the MLT: (1) the vibrational-translational (V-T) relaxation of O2(X3?-g, ? = 1) level by atomic oxygen and (2) the V-V exchange between CO2 and excited O2 molecules [1]. Over the past few years SRI researchers have measured the atomic oxygen removal process mentioned above at room temperature [2] and 240 K [3]. These measurements have been incorporated into the models for H2O(?2) emission [1]. Here we report laboratory studies of the collisional removal of O2(X3?-g, ? = 1) by O(3P) at room temperature and below, reaching temperatures relevant to mesopause and polar summer MLT (~150 K). Instead of directly detecting the O2(X3?-g, ? = 1) population, a technically simpler approach is used in which the ? = 1 level of the O2(a1?g) state is monitored. A two-laser method is employed, in which the pulsed output of the first laser near 285 nm photodissociates ozone to produce atomic oxygen and O2(a1?g, ? = 1), and the pulsed output of the second laser detects O2(a1?g, ? = 1) via resonance-enhanced multiphoton ionization. With ground-state O2 present, owing to the rapid equilibration of the O2(X3?-g, ? = 1) and O2(a1?g, ? = 1) populations via the processes O2(a1?g, ? = 1) + O2(X3?-g, ? = 0) ? O2(a1?g, ? = 0) + O2(X3?-g, ? = 1), the information on the O2(X3?-g, ? = 1) kinetics is extracted from the O2(a1?g, ? = 1) temporal evolution. In addition, measurements of the removal of O2(X3?-g, ? = 1) by CO2 at room temperature will also be presented. This work is supported by the Johns Hopkins University, Applied Physics Laboratory, under grant 939991 (under NASA grant NAG5-13002). [1] Feofilov, A., Kutepov, A. A., Garca-Comas, M., Lpez-Puertas, M., Marshall, B. T., Gordley, L. L., Manuilova, R. O., Yankovsky, V. A., Pesnell, W. D., Goldberg, R. A., Petelina, S. V., and Russell III., J. M. 'SABER/TIMED Observations of Water Vapor in the Mesosphere: Retrieval Methodology and First Results'. Submitted to J. of Atmos. and Terrest. Phys., (2008). [2] Kalogerakis, K. S., Copeland, R. A., and Slanger, T. G., J. of Chem. Phys., 123, 194303, (2005). [3] Pejakovic, D. A., Campbell, Z., Kalogerakis, K. S., Copeland, R. A., and Slanger, T. G., Eos. Trans. AGU 85(47), Fall Meet. Suppl., Abstract SA41A-1032, (2004).

Saran, D. V.; Pejakovic, D. A.; Copeland, R. A.

2008-12-01

26

The XENON Dark Matter Search  

NASA Astrophysics Data System (ADS)

The XENON experiment will search for Weakly Interacting Massive Particles (WIMPS), a leading candidate for the dark matter content of the Universe. The XENON detector uses the simultaneous measurement of ionization and scintillation in liquid xenon to distinguish between nuclear recoils and background electronic interactions. Ionization electrons are extracted into the xenon vapor where they produce a large proportional scintillation signal in a grid assembly. Both prompt and proportional scintillation light are detected by PMT arrays on the top and bottom of the active liquid xenon volume. The distribution of proportional scintillation light in the top PMT array can be used to achieve xy position resolution, while the ionization drift time gives position resolution in the z direction. This allows the definition of a low-background fiducial volume. I describe the results of the R&D phase of this project before providing a status update on the XENON10 phase.

McKinsey, D. N.

2006-11-01

27

Status of XENON100  

NASA Astrophysics Data System (ADS)

XENON100 is a two-phase time projection chamber with a 62 kg liquid xenon target to search for Dark Matter interactions. Both scintillation and ionization signals are recorded to allow interaction vertex reconstruction in three dimensions. Fiducialization of the target volume results in the lowest background level of any running Dark Matter search experiment. In a 48 kg fiducial target and 100.9 days of live time, no evidence for Dark Matter is found. This leads to the strongest limit on elastic spin-independent WIMP-nucleon interactions for WIMP masses above ~ 10 GeV/c2. Also, this data excludes inelastic Dark Matter scattering off sodium or iodine as an explanation of the DAMA modulation.

Lang, Rafael F.; XENON100 Collaboration

2012-07-01

28

Solid Xenon Project  

SciTech Connect

Crystals like Germanium and Silicon need to be grown in specialized facilities which is time and money costly. It takes many runs to test the detector once it's manufactured and mishaps are very probable. It is of a great challenge to grow big germanium crystals and that's why stacking them up in a tower is the only way at the moment to increase testing mass. Liquid Noble gas experiments experiencing contamination problems, their predicted energy resolution at 10 keV and lower energy range is not as good as predicted. Every experiment is targeting one specific purpose, looking for one thing. Why not to design an experiment that is diverse and build a detector that can search for Dark Matter, Solar Axions, Neutrinoless Double Beta decay, etc. Solid Xenon detector is such detector. We designed a simple Xenon crystal growing chamber that was put together at Fermi National Accelerator Laboratory. The first phase of this experiment was to demonstrate that a good, crack free Xenon crystal can be grown (regardless of many failed attempts by various groups) and our first goal, 1 kg crystal, was successful.

Balakishiyeva, Durdana N.; Saab, Tarek [University of Florida (United States); Mahapatra, Rupak [Texas A and M University (United States); Yoo, Jonghee [FNAL (United States)

2010-08-30

29

Nuclear excited xenon flashlamp  

SciTech Connect

The optical emissions of nuclear excited Xenon plasmas were investigated to determine basic parameters important to photolytic pumping of lasers. Gas mixtures of Helium-3 and Xenon were irradiated in the steady state mode in the University of Florida Training Reactor at neutron flux levels of about 10/sup 12//cm/sup 2/.s, generating a power density in the gas of approximately 3 milliwatts/cm/sup 3/. Optical emissions from the gas were primarily due to Xe/sub 2/* band emission at 172 nm with a few Xell lines in the visible and ir. Energy transfer from the /sup 3/He(n,p)T reaction to the Xe/sub 2/* 172 nm band was 67.0% +- 10%. High pressure gas mixtures (4 atm.) of Helium-3 and Xenon were irradiated in the pulse mode (250 ..mu..s FWHM) at the fast burst reactor at the Aberdeen Pulsed Radiation Facility at thermal neutron flux levels of about 10/sup 17//cm/sup 2/.s, generating a power density in the gas of about 1 kilowatt/cm/sup 3/. Optical emissions from the gas extended from the vacuum ultraviolet through the visible to the infrared, resembling a discharge excited lamp with a current density of about 1500 amp./cm/sup 2/. Such a lamp could pump a Neodymium YAG or liquid laser.

Cox, J.D.

1982-01-01

30

ISOTOPIC COMPOSITION OF PRIMORDIAL XENON  

Microsoft Academic Search

A large excess of Xe¹²⁹ and secondary anomalous abundances for ; many of the other isotopes of xenon were previously reported for the meteorite, ; Richardton. Similar secondary anomalies in xenon are reported for the meteorite ; Murray. For every isotope other than Xe¹²⁹, the ratio of the Murray ; percent abundance to the Richardton percent abundance was the same

J. Reynolds

1960-01-01

31

Optical pumping and xenon NMR  

SciTech Connect

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping {sup 129}Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the {sup 131}Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

Raftery, M.D.

1991-11-01

32

Optical pumping and xenon NMR  

SciTech Connect

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

Raftery, M.D.

1991-11-01

33

Mass spectrometric measurement of end-tidal xenon concentration for clinical stable xenon/computerized tomography cerebral blood flow studies.  

PubMed

We have demonstrated the feasibility of using a compact dedicated mass spectrometer to monitor end-tidal xenon concentration in human subjects during stable xenon computerized tomography measurements of regional cerebral blood flow. End-tidal carbon dioxide concentration is monitored simultaneously and noninvasively without degrading the dynamic response to xenon. For clinical regional cerebral blood flow studies we employed a Nuclide 3-60-G Sectorr mass spectrometer with a 3 in radius, 60 degrees magnetic sector and a variable (0-5000 V) ion accelerating potential. The required high vacuum (10(-7) Torr) was achieved and maintained by means of a turbomolecular pump. A needlemetering valve was incorporated into an anesthesia mask connector, and exhaled gases were transported to the mass spectrometer via a 6 ft length of Teflon tubing (1/16 in i.d.). Molecular flow conditions between the sample and analysis chambers were provided by use of a gold foil leak (0.0005 in. hole). At an inlet pressure of 400 m Torr (achieved by means of the needle valve), the inlet system was characterized by a gas transport lag-time of 1.3 s and a rise-time constant of 85 ms. Xenon (doubly charged ion: m/z 68) and carbon dioxide (doubly charged ion: m/z 22) were monitored alternately at 75 ms intervals. Our experience with mass spectrometry has demonstrated the feasibility of using a compact dedicated instrument for accurately and non-invasively monitoring end-tidal xenon concentration in a clinical setting. PMID:6809066

Dhawan, V; Goldiner, P; Ray, C; Conti, J; Rottenberg, D A

1982-06-01

34

The Enriched Xenon Observatory  

SciTech Connect

The Enriched Xenon Observatory (EXO) experiment will search for neutrinoless double beta decay of {sup 136}Xe. The EXO Collaboration is actively pursuing both liquid-phase and gas-phase Xe detector technologies with scalability to the ton-scale. The search for neutrinoless double beta decay of {sup 136}Xe is especially attractive because of the possibility of tagging the resulting Ba daughter ion, eliminating all sources of background other than the two neutrino decay mode. EXO-200, the first phase of the project, is a liquid Xe time projection chamber with 200 kg of Xe enriched to 80% in {sup 136}Xe. EXO-200, which does not include Ba-tagging, will begin taking data in 2009, with two-year sensitivity to the half-life for neutrinoless double beta decay of 6.4x10{sup 25} years. This corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV.

Dolinski, M. J. [Stanford University Physics Department, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

2009-12-17

35

The Enriched Xenon Observatory  

NASA Astrophysics Data System (ADS)

The Enriched Xenon Observatory (EXO) experiment will search for neutrinoless double beta decay of 136Xe. The EXO Collaboration is actively pursuing both liquid-phase and gas-phase Xe detector technologies with scalability to the ton-scale. The search for neutrinoless double beta decay of 136Xe is especially attractive because of the possibility of tagging the resulting Ba daughter ion, eliminating all sources of background other than the two neutrino decay mode. EXO-200, the first phase of the project, is a liquid Xe time projection chamber with 200 kg of Xe enriched to 80% in 136Xe. EXO-200, which does not include Ba-tagging, will begin taking data in 2009, with two-year sensitivity to the half-life for neutrinoless double beta decay of 6.41025 years. This corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV.

Dolinski, M. J.

2009-12-01

36

Solubilized xenon 133 lung scintigraphy  

SciTech Connect

Lung scanning using solubilized xenon 133 can provide important information concerning both pulmonary perfusion and ventilation. This technique proved valuable in establishing the diagnosis of congenital lobar emphysema in a 7-month-old baby.

Oates, E.; Sarno, R.C.

1988-11-01

37

Optical pumping and xenon NMR.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness an...

M. D. Raftery

1991-01-01

38

XENON TETRAFLUORIDE: HEAT OF FORMATION  

Microsoft Academic Search

Calorimetric measurements of the heat of reaction of xenon tetrafluoride ; with aqueous iodide solution give -- 60 kilocalories per mole for the standard ; heat of formation, or an average thermochemical bond energy of about 31 ; kilocalories. (auth);

S. R. Gunn; S. M. Williamson

1963-01-01

39

The XENON100 Dark Matter Experiment  

SciTech Connect

The XENON Dark Matter Experiment aims at the direct detection of dark matter Weakly Interacting Massive Particles (WIMPs) with dual phase (liquid/gas) xenon time projection chambers (XeTPCs). Following the successful performance of the XENON10 detector, which has shown in 2007 the best sensitivity to spin-independent coupling of WIMPs to matter, we have designed and completed the construction of a new TPC with an active LXe shield, containing a total of 170 kg of xenon. The detector is currently undergoing final commissioning at the Gran Sasso Underground Laboratory. I will review the XENON10 results and present the status of the XENON100 experiment.

Aprile, Elena [Department of Physics, Columbia University, New York, NY 10027 (United States)

2009-04-17

40

High-efficiency plasma display panel based on a high xenon mole fraction  

SciTech Connect

The luminance efficiency of a plasma display panel is directly related to the vacuum-ultraviolet (VUV) light emitted from excited xenon atoms and molecules. The emission efficiency of 173 nm VUV light is measured in terms of the xenon mole fraction ({chi}) and is shown to become considerably enhanced at a high xenon mole fraction. For example, the emission efficiency at {chi}=0.35 under a pressure of 400 Torr is more than 2.5 times that at {chi}=0.1. The experimental data agree remarkably well with theoretical predictions.

Uhm, Han S. [Department of Molecular Science and Technology, Ajou University, Suwon 443-949 (Korea, Republic of); Son, Chang G.; Hong, Byung H.; Choi, Eun H. [PDP Research Center, Department of Electrophysics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2009-09-15

41

2D multinuclear NMR, hyperpolarized xenon and gas storage in organosilica nanochannels with crystalline order in the walls.  

PubMed

The combination of 2D 1H-13C and 1H-29Si solid state NMR, hyperpolarized 129Xe NMR, synchrotron X-ray diffraction, together with adsorption measurements of vapors and gases for environmental and energetic relevance, was used to investigate the structure and the properties of periodic mesoporous hybrid p-phenylenesilica endowed with crystalline order in the walls. The interplay of 1H, 13C, and 29Si in the 2D heteronuclear correlation NMR measurements, together with the application of Lee-Goldburg homonuclear decoupling, revealed the spatial relationships (<5 angstroms) among various spin-active nuclei of the framework. Indeed, the through-space correlations in the 2D experiments evidenced, for the first time, the interfaces of the matrix walls with guest molecules confined in the nanochannels. Organic-inorganic and organic-organic heterogeneous interfaces between the matrix and the guests were identified. The open-pore structure and the easy accessibility of the nanochannels to the gas phase have been demonstrated by highly sensitive hyperpolarized (HP) xenon NMR, under extreme xenon dilution. Two-dimensional exchange experiments showed the exchange time to be as short as 2 ms. Through variable-temperature HP 129Xe NMR experiments we were able to achieve an unprecedented description of the nanochannel space and surface, a physisorption energy of 13.9 kJ mol-1, and the chemical shift value of xenon probing the internal surfaces. These results prompted us to measure the high storage capacity of the matrix towards benzene, hexafluorobenzene, ethanol, and carbon dioxide. Both host-guest, CH...pi, and OH...pi interactions contribute to the stabilization of the aromatic guests (benzene and hexafluorobenzene) on the extended surfaces. The full carbon dioxide loading in the channels could be detected by synchrotron radiation X-ray diffraction experiments. The selective adsorption of carbon dioxide (ca. 90 wt %) vs that of oxygen and hydrogen, together with the permanent porosity, high thermal stability, and high degree of order, makes this a suitable matrix for purifying hydrogen in clean-energy generation. PMID:17579407

Comotti, Angiolina; Bracco, Silvia; Valsesia, Patrizia; Ferretti, Lisa; Sozzani, Piero

2007-06-19

42

The fate of xenon-131 from iodine-131 absorbed on the silver zeolite samplers  

NASA Astrophysics Data System (ADS)

The purpose of this study was to investigate whether xenon-131, the decay daughter of I-131, was retained in or escaped from the silver zeolite cartridge after iodine-131 had been adsorbed in the cartridge. Currently, silver zeolite cartridges are used in the nuclear power industry to adsorb the radioactive iodine gas in sampling lines because of their high retention efficiency for gaseous iodine but not for noble gases. If xenon-131 is desorbed and escapes from the silver zeolite cartridge, the surfaces originally occupied by iodine-131 in the silver zeolite cartridge may be vacant and thus available to adsorb other iodine gas molecules. The reusability of silver zeolite cartridges may reduce the sampling cost and radioactive waste volume and also preserve the silver resource. A silver zeolite cartridge containing only iodine-131 of known activity in a cartridge holder was connected with a blank charcoal cartridge in another cartridge holder. The end of each cartridge holder was sealed so the diffusion of xenon was contained in a closed system. Radioactive xenon-131 m, the daughter of iodine-131, was used as an indicator for stable xenon-131. The absence or presence of xenon-131m on the charcoal cartridge was used to determine if xenon-131 was desorbed from the silver zeolite cartridge. A NaI scintillator was used to detect iodine-131 and a HPGe detector was used to detect xenon- 131 m. The desorption fraction of xenon-133 from the silver zeolite cartridge was found to be 0.66 +/- 4.3% and the retention fraction of xenon-133 in the charcoal cartridge was found to be 0.61 +/- 7.5%. Xenon-131m was frequently present in the charcoal cartridge. This showed that xenon131 was desorbed and escaped from the initial occupied sites in the silver zeolite cartridge after iodine-131 decayed. The amount of xenon-131m escaping from the silver zeolite cartridge fluctuated from day to day. This is thought to be due to what is known as the tunnel blocking effect. This effect has been described in the literature and involves the random location of xenon-131m atoms in the microscopic infrastructure of the silver zeolite.

Wang, Wei-Hsung

2000-09-01

43

Fluorine Compounds of Xenon and Radon  

Microsoft Academic Search

Xenon and fluorine combine readily. Xenon tetrafluoride is a colorless crystalline material, stable at room temperature. The existence of at least one other fluoride and two oxyfluorides has been demonstrated. The heaviest \\

C. L. Chernick; H. H. Claassen; P. R. Fields; H. H. Hyman; J. G. Malm; W. M. Manning; M. S. Matheson; L. A. Quarterman; F. Schreiner; H. H. Selig; I. Sheft; S. Siegel; E. N. Sloth; L. Stein; M. H. Studier; M. H. Zirin

1962-01-01

44

Inhalation anaesthesia: from diethyl ether to xenon.  

PubMed

Modern anaesthesia is said to have began with the successful demonstration of ether anaesthesia by William Morton in October 1846, even though anaesthesia with nitrous oxide had been used in dentistry 2 years before. Anaesthesia with ether, nitrous oxide and chloroform (introduced in 1847) rapidly became commonplace for surgery. Of these, only nitrous oxide remains in use today. All modern volatile anaesthetics, with the exception of halothane (a fluorinated alkane), are halogenated methyl ethyl ethers. Methyl ethyl ethers are more potent, stable and better anaesthetics than diethyl ethers. They all cause myocardial depression, most markedly halothane, while isoflurane and sevoflurane cause minimal cardiovascular depression. The halogenated ethers also depress the normal respiratory response to carbon dioxide and to hypoxia. Other adverse effects include hepatic and renal damage. Hepatitis occurs most frequently with halothane, although rare cases have been reported with the other agents. Liver damage is not caused by the anaesthetics themselves, but by reactive metabolites. Type I hepatitis occurs fairly commonly and takes the form of a minor disturbance of liver enzymes, which usually resolves without treatment. Type II, thought to be immune-mediated, is rare, unpredictable and results in a severe fulminant hepatitis with a high mortality. Renal damage is rare, and was most often associated with methoxyflurane because of excessive plasma fluoride concentrations resulting from its metabolism. Methoxyflurane was withdrawn from the market because of the high incidence of nephrotoxicity. Among the contemporary anaesthetics, the highest fluoride concentrations have been reported with sevoflurane, but there are no reports of renal dysfunction associated with its use. Recently there has been a renewed interest in xenon, one of the noble gases. Xenon has many of the properties of an ideal anaesthetic. The major factor limiting its more widespread is the high cost, about 2,000 times the cost of nitrous oxide. PMID:18175089

Bovill, J G

2008-01-01

45

The growth of fission gas bubbles in irradiated uranium dioxide  

Microsoft Academic Search

The growth of fission gas bubbles from supersaturated solution in irradiated uranium dioxide has been studied by electron microscopy under isothermal annealing conditions between 1300 and 1500C. Measurements of the kinetics of bubble growth have enabled the diffusion coefficients of atomic xenon and krypton in irradiated uranium dioxide to be determined. The diffusion coefficients obtained may be expressed by the

R. M. Cornell

1969-01-01

46

The XENON dark matter experiment: status of the XENON10 phase  

NASA Astrophysics Data System (ADS)

The XENON experiment searches for Weakly Interacting Massive Particles (WIMPs) with liquid Xenon as the active target. The proposed XENON1T detector is designed to achieve a sensitivity more than a factor of thousand beyond current limits. The collaboration is now testing the 10 kg target: the XENON10 detector was recently installed at the Gran Sasso Underground Laboratory and the first phase of data taking is underway.

the XENON Collaboration; Monzani, Maria Elena

2011-12-01

47

Single molecule magnets with protective ligand shells on gold and titanium dioxide surfaces: In situ electrospray deposition and x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Two single molecule magnets based on the dodecamanganese (III, IV) cluster with either benzoate or terphenyl-4-carboxylate ligands, have been studied on the Au(111) and rutile TiO2(110) surfaces. We have used in situ electrospray deposition to produce a series of surface coverages from a fraction of a monolayer to multilayer films in both cases. X-ray absorption spectroscopy measured at the Mn L-edge (Mn 2p) has been used to study the effect of adsorption on the oxidation states of the manganese atoms in the core. In the case of the benzoate-functionalised complex reduction of the manganese metal centres is observed due to the interaction of the manganese core with the underlying surface. In the case of terphenyl-4-carboxylate, the presence of this much larger ligand prevents the magnetic core from interacting with either the gold or the titanium dioxide surfaces and the characteristic Mn3+ and Mn4+ oxidation states necessary for magnetic behaviour are preserved.

Handrup, Karsten; Richards, Victoria J.; Weston, Matthew; Champness, Neil R.; O'Shea, James N.

2013-10-01

48

Single molecule magnets with protective ligand shells on gold and titanium dioxide surfaces: In situ electrospray deposition and x-ray absorption spectroscopy.  

PubMed

Two single molecule magnets based on the dodecamanganese (III, IV) cluster with either benzoate or terphenyl-4-carboxylate ligands, have been studied on the Au(111) and rutile TiO2(110) surfaces. We have used in situ electrospray deposition to produce a series of surface coverages from a fraction of a monolayer to multilayer films in both cases. X-ray absorption spectroscopy measured at the Mn L-edge (Mn 2p) has been used to study the effect of adsorption on the oxidation states of the manganese atoms in the core. In the case of the benzoate-functionalised complex reduction of the manganese metal centres is observed due to the interaction of the manganese core with the underlying surface. In the case of terphenyl-4-carboxylate, the presence of this much larger ligand prevents the magnetic core from interacting with either the gold or the titanium dioxide surfaces and the characteristic Mn(3+) and Mn(4+) oxidation states necessary for magnetic behaviour are preserved. PMID:24160534

Handrup, Karsten; Richards, Victoria J; Weston, Matthew; Champness, Neil R; O'Shea, James N

2013-10-21

49

Weird muonium diffusion in solid xenon  

Microsoft Academic Search

Muon and muonium spin rotation and relaxation parameters were studied in liquid and solid xenon. The small diamagnetic fraction (~10%) observed in condensed xenon is believed to be Xemu+. The muonium hyperfine frequency was measured for the first time in liquid Xe and was found to be in agreement with the vacuum value. A nonmonotonic temperature dependence of the muonium

V. G. Storchak; B. F. Kirillov; A. V. Pirogov; V. A. Duginov; V. G. Grebinnik; T. N. Mamedov; V. G. Ol'Shevsky; V. A. Xhukov; J. H. Brewer; G. D. Morris

1992-01-01

50

Xenon and Krypton in the Bruderheim Meteorite  

Microsoft Academic Search

In a series of heating experiments, xenon, radiogenic XeR, and krypton con- tents, and the xenon and krypton isotopic composition of the Bruderheim meteorite were studied for the separated minerals feldspar, pyroxene, olivine, and trollire and for numerous chondrule fractions. Important differences among the individual minerals and between min- erals and chondrules were observed, and the following conclusions were reached:

Craig Merrihue

1966-01-01

51

Results from the XENON1T Demonstrator  

NASA Astrophysics Data System (ADS)

The current stage of the XENON Dark Matter Search project, XENON100, constitutes one of the best performing dark matter experiments in the world, setting the best upper limit on the cross section for spin independent WIMP-nucleus scattering. The next generation detector within the program, XENON1T, is at the end of its design phase and construction will start in the present year. XENON1T is a liquid xenon dual-phase time projection chamber with a 1 Ton fiducial mass, and it will improve the present XENON100 limit by 2 orders of magnitude. However, the increase in mass in the new detector presents several technological challenges. In order to address the required improvements, a fully operational prototype of the detector, the XENON1T Demonstrator, has been built at Columbia University. In this talk we will present the main results of the XENON1T Demonstrator R&D program, comprising high-speed recirculation on a full-scale cryogenic system, the observation of electron drift over 30 cm, and the operation of the detector with a cathode high voltage exceeding 30kV and preliminary results of the new 60 and 100 cm setups.

Contreras, Hugo; Aprile, Elena; Budnik, Ranny; Goetzke, Luke; Plante, Guillaume; Messina, Marcello; Rizzo, Alfio; Melgarejo, Antonio; Naganoma, Junji; Chaguine, Petr

2013-04-01

52

Marvelous Molecules  

NSDL National Science Digital Library

Presented by the New York Hall of Science, the Marvelous Molecules Web site accompanies its physical museum's exhibit by offering descriptions and additional online activities. The first page "About the Exhibit" shows what is available at the museum and gives interesting facts about molecules. The next page "All About Molecules" explains what a molecule is and gives eight examples (e.g., aspirin and carbon dioxide). The next page called "Marvelous Activities" contains several activities, one of which is the "How Many Molecules Are You?" interactive exercise. Here, users input their weight to see how many molecules their bodies contain and how that compares to other living things. Geared mainly towards kids, the Web site should give all people a fun way to learn.

1969-12-31

53

Extended photoionization calculations for xenon  

NASA Astrophysics Data System (ADS)

Partial photoionization cross sections and angular distribution asymmetry parameters for atomic xenon have been calculated in the relativistic random-phase approximation for 26 jj-coupled channels over a wide range of energies (0-1 keV). The effects of relaxation on the 4d and 3d cross sections are examined by using a modification of the relativistic random-phase approximation that calculates excited-state orbitals in the potential of the relaxed ion. Results are compared with Hartree-Fock theory, with the nonrelativistic random-phase approximation, and with recent photoemission experiments.

Kutzner, M.; Radojevi?, V.; Kelly, H. P.

1989-11-01

54

Xenon Gamma Detector Project Support  

SciTech Connect

This project provided funding of $48,500 for part of one year to support the development of compressed xenon spectrometers at BNL. This report describes upgrades that were made to the existing detector system electronics during that period, as well as subsequent testing with check sources and Special Nuclear Materials. Previous testing of the equipment extended only up to the energy of 1.3 MeV, and did not include a spectrum of Pu-239. The new electronics allowed one-button activation of the high voltage ramp that was previously controlled by manual adjustments. Mechanical relays of the charging circuit were replaced by a tera-ohm resistor chain and an optical switch. The preamplifier and shaping amplifier were replaced by more modern custom designs. We found that the xenon purity had not been degraded since the chamber was filled 10 years earlier. The resulting spectra showed significantly better resolution than sodium iodide spectra, and could be analyzed quite effectively by methods using peak area templates.

Vanier,P.E.; Forman, L.

2008-04-01

55

High pressure xenon ionization detector  

DOEpatents

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

Markey, J.K.

1989-11-14

56

Xenon spill distribution and room clearance.  

PubMed

The purpose of these studies was to investigate actual xenon gas clearance times under different exhaust conditions, to compare them with the calculated clearance times, to observe the distribution of the xenon gas while it was being exhausted from the room, and to determine the cause of a stationary xenon cloud that appeared on some clinical images. Clearance times with and without a flexible exhaust hose placed next to a simulated 133Xe gas spill were compared with clearance times measured in a room with all exhaust closed off. Two gamma cameras were used to observe the transport and exhaust of xenon following a simulated spill. Clearance times with the flexible exhaust hose were less than one minute because the xenon gas was removed before it had a chance to disperse into the room. Conventional room clearance calculations based on uniform mixing and measured exhaust rates yielded a clearance time of 22 min. The source of an artifactual stationary cloud image was discovered to be a small amount of xenon trapped between the collimator and camera face. A negative pressure and dedicated exhaust can be even more effective in exhausting spilled xenon from a room than air transfer calculations predict. The authors believe the flexible hose should always be used. PMID:10524516

Kelsey, C A; Telepak, R J

1999-11-01

57

Effect of xenon binding to a hydrophobic cavity on the proton pumping cycle in bacteriorhodopsin.  

PubMed

To understand the functional role of apolar cavities in bacteriorhodopsin, a light-driven proton pump found in Halobacterium salinarum, we investigated the crystal structure in pressurized xenon or krypton. Diffraction data from the P622 crystal showed that one Xe or Kr atom binds to a preexisting hydrophobic cavity buried between helices C and D, located at the same depth from the membrane surface as Asp96, a key residue in the proton uptake pathway. The occupation fraction of Xe or Kr was calculated as approximately 0.32 at a pressure of 1 MPa. In the unphotolyzed state, the binding of Xe or Kr caused no large deformation of the cavity. However, the proton pumping cycle was greatly perturbed when an aqueous suspension of purple membrane was pressurized with xenon gas; that is, the decay of the M state was accelerated significantly (~5 times at full occupancy), while the decay of an equilibrium state of N and O was slightly decelerated. A similar but much smaller perturbation in the reaction kinetics was observed upon pressurization with krypton gas. In a glycerol/water mixture, xenon-induced acceleration of M decay became less significant in proportion to the water activity. Together with the structure of the xenon-bound protein, these observations suggest that xenon binding helps water molecules permeate into apolar cavities in the proton uptake pathway, thereby accelerating the water-mediated proton transfer from Asp96 to the Schiff base. PMID:18930734

Hayakawa, Naoki; Kasahara, Takashi; Hasegawa, Daisuke; Yoshimura, Keiko; Murakami, Midori; Kouyama, Tsutomu

2008-10-09

58

New applications for the stable xenon/CT method  

NASA Astrophysics Data System (ADS)

The stable xenon/CT method has been expanded to study in addition to the tissue flow the flow of the vessels in the brain. This method was then applied to a series of baboon experiments to measure the flow and diameters of vessels and their dependence on the partial pressure of carbon dioxide (PACO2). The method uses the value of the flow to distinguish vessels from tissues. The results from an experimental animal study show that (1) the location of the vessels with a diameter larger than 0.3 mm can be detected, (2) the vessel flow follows a Poiseuilles type law, (3) the average of the vessel flow is much higher near the skull at low PaCO2, whereas at high PaCO2 the average vessel flow is nearer the center.

Wist, Abund O.; Cothran, Stafford J.; Fatouros, Panos P.

1993-09-01

59

Xenon worth calculations for plant operations  

SciTech Connect

Estimates of xenon worth for nonequilibrium operating histories based on calculations using a point model can be inaccurate due to the spatial distributions of the xenon and neutron flux. The magnitude of the misprediction can be as high as 700 pcm. This misprediction can lead to incorrect reactivity balance calculations for SDM surveillance and ECP calculations. The PC1D program uses a one-dimensional, two-group neutron diffusion model with a variable radial buckling correlation to accurately calculate xenon worth. Accuracy within 10 ppm can be expected for xenon worth calculations using the PC1D program. This will result in improved ECP and SDM surveillance calculations and in most cases will translate into reduced boron processing costs for the utility.

Leach, D.S.; Alsop, B.A..; Kapil, S.K.

1988-01-01

60

Surface Area Measurements Using Polarized Xenon NMR  

NASA Astrophysics Data System (ADS)

We developed a new NMR technique to measure the surface area of xenon-soluble porous media such as compacted polyethylene granulates (used in filtering, wicking, etc.), packs of polymeric beads (used for molecular fractionation, including radio-immunoassay), and lung tissue. The large chemical shift of the 129Xe NMR frequency enables independent observation and manipulation of both the dissolved and gas phase xenon resonances. The measured short-time rate of xenon interphase exchange depends on the surface area of the interface between the dissolved and gas phases. The porosity and surface area of four porous polymer solids were measured with xenon interphase exchange NMR, in good agreement with independent measurements obtained by confocal microscopy.

Mair, R. W.; Hoffmann, D.; Walsworth, R. L.; Butler, J. P.; Patz, S.; Topulos, G. P.

2000-06-01

61

Material screening and selection for XENON100  

NASA Astrophysics Data System (ADS)

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.

Aprile, E.; Arisaka, K.; Arneodo, F.; Askin, A.; Baudis, L.; Behrens, A.; Bokeloh, K.; Brown, E.; Cardoso, J. M. R.; Choi, B.; Cline, D.; Fattori, S.; Ferella, A. D.; Giboni, K. L.; Kish, A.; Lam, C. W.; Lamblin, J.; Lang, R. F.; Lim, K. E.; Lopes, J. A. M.; Marrodn Undagoitia, T.; Mei, Y.; Melgarejo Fernandez, A. J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Plante, G.; Ribeiro, A. C. C.; Santorelli, R.; dos Santos, J. M. F.; Schumann, M.; Shagin, P.; Teymourian, A.; Thers, D.; Tziaferi, E.; Wang, H.; Weinheimer, C.; Laubenstein, M.; Nisi, S.

2011-09-01

62

Effect of xenon on endotracheal tube cuff  

Microsoft Academic Search

Study Design:To investigate the effect of xenon on the endotracheal tube cuff in comparison to that of nitrous oxide.Design:Prospective, randomized study.Setting:Laboratory in vitro testing of endotracheal tubes.Interventions:Exposure of air-filled endotracheal tube cuffs to xenon or nitrous oxide (79 vol%) mixed with a balance of oxygen (21 vol%) for 3 hours.Measurements:The intra-cuff pressure and gas volume in the cuff were measured

Yoshiki Ishiguro; Hayato Saito; Yoshinori Nakata; Takahisa Goto; Katsuo Terui; Yoshinari Niimi; Shigeho Morita

2000-01-01

63

Transportable Xenon Laboratory (TXL-1) Operations Manual  

SciTech Connect

The Transportable Xenon Laboratory Operations Manual is a guide to set up and shut down TXL, a fully contained laboratory made up of instruments to identify and measure concentrations of the radioactive isotopes of xenon by taking air samples and analyzing them. The TXL is housed in a standard-sized shipping container. TXL can be shipped to and function in any country in the world.

Thompson, Robert C.; Stewart, Timothy L.; Willett, Jesse A.; Woods, Vincent T.

2011-03-07

64

The XENON100 dark matter experiment  

NASA Astrophysics Data System (ADS)

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to search for xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper we present a detailed description of the detector design and present performance results, as established during the commissioning phase and during the first science runs.The active target of XENON100 contains 62 kg of LXe, surrounded by an LXe veto of 99 kg, both instrumented with photomultiplier tubes (PMTs) operating inside the liquid or in xenon gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield and is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The experiment has recently published results from a 100 live-days dark matter search. The ultimate design goal of XENON100 is to achieve a spin-independent WIMP-nucleon scattering cross section sensitivity of ? = 2 10-45 cm2 for a 100 GeV/c2 WIMP.

Xenon100 Collaboration; Aprile, E.; Arisaka, K.; Arneodo, F.; Askin, A.; Baudis, L.; Behrens, A.; Brown, E.; Cardoso, J. M. R.; Choi, B.; Cline, D.; Fattori, S.; Ferella, A. D.; Giboni, K. L.; Kish, A.; Lam, C. W.; Lang, R. F.; Lim, K. E.; Lopes, J. A. M.; Marrodn Undagoitia, T.; Mei, Y.; Melgarejo Fernandez, A. J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Plante, G.; Ribeiro, A. C. C.; Santorelli, R.; Dos Santos, J. M. F.; Schumann, M.; Shagin, P.; Teymourian, A.; Tziaferi, E.; Wang, H.; Yamashita, M.

2012-04-01

65

Interaction of phenol with xenon and nitrogen: Spectroscopic and computational characterization  

NASA Astrophysics Data System (ADS)

Intermolecular complexes of phenol with xenon and nitrogen are studied by infrared absorption spectroscopy in a neon matrix and by quantum chemistry calculations. The ? complex is theoretically the most stable 1:1 phenol...Xe structure, but it has no characteristic shifts in the calculated vibrational spectrum, which complicates its experimental characterization. However, the formation of the ? complex finds indirect but significant support from the experimental results. The calculated spectrum of the less stable H-bonded complex shows a number of characteristic absorptions, but they are not observed in the experiment, indicating the lack of its formation. For the phenol...Xen (n = 2-4) complexes, the calculations predict substantial changes in the vibrational spectra, and the corresponding bands are observed in the matrices with large concentrations of xenon. Our experiments show the high efficiency of the formation of large xenon clusters in a neon matrix that can accommodate a major part of phenol molecules. In contrast to the case of xenon, the H-bonded 1:1 phenol...N2 complex is found in a neon matrix, and the formation of large N2 clusters embedding phenol molecules is relatively inefficient.

Cao, Qian; Andrijchenko, Natalya; Ahola, Anna-Elina; Domanskaya, Alexandra; Rsnen, Markku; Ermilov, Alexander; Nemukhin, Alexander; Khriachtchev, Leonid

2012-10-01

66

Interaction of phenol with xenon and nitrogen: spectroscopic and computational characterization.  

PubMed

Intermolecular complexes of phenol with xenon and nitrogen are studied by infrared absorption spectroscopy in a neon matrix and by quantum chemistry calculations. The ? complex is theoretically the most stable 1:1 phenol???Xe structure, but it has no characteristic shifts in the calculated vibrational spectrum, which complicates its experimental characterization. However, the formation of the ? complex finds indirect but significant support from the experimental results. The calculated spectrum of the less stable H-bonded complex shows a number of characteristic absorptions, but they are not observed in the experiment, indicating the lack of its formation. For the phenol???Xe(n) (n = 2-4) complexes, the calculations predict substantial changes in the vibrational spectra, and the corresponding bands are observed in the matrices with large concentrations of xenon. Our experiments show the high efficiency of the formation of large xenon clusters in a neon matrix that can accommodate a major part of phenol molecules. In contrast to the case of xenon, the H-bonded 1:1 phenol???N(2) complex is found in a neon matrix, and the formation of large N(2) clusters embedding phenol molecules is relatively inefficient. PMID:23039597

Cao, Qian; Andrijchenko, Natalya; Ahola, Anna-Elina; Domanskaya, Alexandra; Rsnen, Markku; Ermilov, Alexander; Nemukhin, Alexander; Khriachtchev, Leonid

2012-10-01

67

Measurement of radon and xenon binding to a cryptophane molecular host.  

PubMed

Xenon and radon have many similar properties, a difference being that all 35 isotopes of radon ((195)Rn-(229)Rn) are radioactive. Radon is a pervasive indoor air pollutant believed to cause significant incidence of lung cancer in many geographic regions, yet radon affinity for a discrete molecular species has never been determined. By comparison, the chemistry of xenon has been widely studied and applied in science and technology. Here, both noble gases were found to bind with exceptional affinity to tris-(triazole ethylamine) cryptophane, a previously unsynthesized water-soluble organic host molecule. The cryptophane-xenon association constant, K(a)=42,000 2,000 M(-1) at 293 K, was determined by isothermal titration calorimetry. This value represents the highest measured xenon affinity for a host molecule. The partitioning of radon between air and aqueous cryptophane solutions of varying concentration was determined radiometrically to give the cryptophane-radon association constant K(a)=49,000 12,000 M(-1) at 293 K. PMID:21690357

Jacobson, David R; Khan, Najat S; Coll, Ronald; Fitzgerald, Ryan; Laureano-Prez, Lizbeth; Bai, Yubin; Dmochowski, Ivan J

2011-06-20

68

Measurement of radon and xenon binding to a cryptophane molecular host  

PubMed Central

Xenon and radon have many similar properties, a difference being that all 35 isotopes of radon (195Rn229Rn) are radioactive. Radon is a pervasive indoor air pollutant believed to cause significant incidence of lung cancer in many geographic regions, yet radon affinity for a discrete molecular species has never been determined. By comparison, the chemistry of xenon has been widely studied and applied in science and technology. Here, both noble gases were found to bind with exceptional affinity to tris-(triazole ethylamine) cryptophane, a previously unsynthesized water-soluble organic host molecule. The cryptophanexenon association constant, Ka=42,0002,000M-1 at 293K, was determined by isothermal titration calorimetry. This value represents the highest measured xenon affinity for a host molecule. The partitioning of radon between air and aqueous cryptophane solutions of varying concentration was determined radiometrically to give the cryptophaneradon association constant Ka=49,00012,000M-1 at 293K.

Jacobson, David R.; Khan, Najat S.; Colle, Ronald; Fitzgerald, Ryan; Laureano-Perez, Lizbeth; Bai, Yubin; Dmochowski, Ivan J.

2011-01-01

69

The Search for Dark Matter with the XENON100 Experiment  

SciTech Connect

The XENON Dark Matter Experiment aims at the direct detection of dark matter Weakly Interacting Massive Particles (WIMPs) with dual phase (liquid/gas) xenon time projection chambers (XeTPCs). Following the successful performance of the XENON10 detector, which has shown in 2007 the best sensitivity to spin-independent coupling of WIMPs to matter, we have designed and completed the construction of a new TPC with an active LXe shield, containing a total of 170 kg of xenon. The detector is currently undergoing final commissioning at the Gran Sasso Underground Laboratory. I will review the XENON10 results and present the status of the XENON100 experiment.

Aprile, Elena [Columbia University (United States)

2008-11-23

70

The Systems Xenon Hexafluoride - Germanium Tetrafluoride and Xenon Hexafluoride - Silicon Tetrafluoride.  

National Technical Information Service (NTIS)

Xenon hexafluoride and germanium tetrafluoride, when mixed in the proper proportions, produce the compounds 4XeF6.GeF4, 2XeF6.GeF4 and XeF6.GeF4. Xenon hexafluoride appears not to react with silicon tetrafluoride. (Author)

K. E. Pullen G. H. Cady

1967-01-01

71

The XENON Dark Matter Project: Status of the XENON100 Phase  

SciTech Connect

The XENON100 experiment aims to detect cold dark matter particles via their elastic collisions with xenon nuclei. An ultra-low background, two-phase time projection chamber with a total of 170 kg of xenon (65 kg in the target region and 105 kg in the active veto) has been installed at the Gran Sasso Underground Laboratory and is currently in commissioning phase. We review the design and performance of the detector and its associated systems, present status, preliminary calibration results, background prediction and projected sensitivity. With a 6000 kg-day background-free exposure, XENON100 will reach a sensitivity of spin-independent WIMP-nucleon cross section of 2x10{sup -45} cm{sup 2} by the end of 2009. We also discuss our plan to upgrade the XENON100 experiment to improve the sensitivity by another order of magnitude by 2012.

Aprile, Elena [Physics Department and Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States)

2009-09-08

72

Xenon consumption during general surgery: a retrospective observational study  

PubMed Central

Background High costs still limits the widespread use of xenon in the clinical practice. Therefore, we evaluated xenon consumption of different delivery modes during general surgery. Methods A total of 48 patients that underwent general surgery with balanced xenon anaesthesia were retrospectively analysed according to the mode of xenon delivery during maintenance phase (ECO mode, AUTO mode or MANUAL mode). Results Xenon consumption was highest during the wash-in phase (9.4??2.1l) and further decreased throughout maintenance of anaesthesia. Comparison of different xenon delivery modes revealed significant reduced xenon consumption during ECO mode (18.5??3.7L (ECO) vs. 24.7??11.5L (AUTO) vs. 29.6??14.3L (MANUAL); p?=?0.033). No differences could be detected with regard to anaesthetic depth, oxygenation or performance of anaesthesia. Conclusion The closed-circuit respirator Felix Dual offers effective reduction of xenon consumption during general surgery when ECO mode is used.

2013-01-01

73

Transuranic actinide reactions with simple gas-phase molecules.  

SciTech Connect

The intent of this research is to conduct an experimental study of f-element chemistry fo r the purpose of identifying reaction trends and mechanisms of the early actinide metals with simple gas phase molecules . Previous research has elucidated some of the fundamenta l chemistry of the 4f elements,1-5 however, more complex chemistry is expected for the 5f serie s due to the inclusion of the 5f electrons in the valence shell . The matrix isolation approach, which is well-suited to the experimental study of transient species, will be used for sample collection, and IR/NIR/VIS spectroscopy will be employed to interrogate deposited matrices . The strength of this method lies in the use of isotopes of reactants, which permits the identification of guest molecules in a noble gas matrix by observation of vibrational frequenc y shifts and patterns upon isotopic substitution . Using this technique at the University of Virginia, the first noble gas-actinide bond has recently been identified, a weak U-Ar bond on the CUO molecule.6 Uranium has similarly been observed to bond to krypton and xenon, whereas thoriu m and the lanthanides have not exhibited this activity . It is expected that plutonium will be even more reactive in this respect . We will extend the body of actinide experimental evidence t o include the transuranic elements neptunium, plutonium, and americium reacted with isotopes o f oxygen, nitrogen, hydrogen, carbon monoxide, and carbon dioxide .

Willson, S. P. (Stephen P.); Veirs, D. K. (Douglas Kirk); Baiardo, J. P. (Joseph P.)

2003-01-01

74

The Xenon record of Earth's early differentiaiton  

NASA Astrophysics Data System (ADS)

Xenon isotopes in mantle derived rocks provide information on the early differentiation of the silicate mantle of our planet. {131,132 134,136}Xe isotopes are produced by the spontaneous fission of two different elements: the now extinct radionuclide 244Pu, and the long-lived 238U. These two parent nuclides, however, yield rather different proportion of fissiogenic Xenon isotopes. Hence, the proportion of Pu- to U-derived fission xenon is indicative of the degree and rate of outgassing of a mantle reservoir. Recent data obtained from Iceland in our lab confirm that the Xenon isotopic composition of the plume source(s) is characterized by lower 136Xe/130Xe ratios than the MORB source and the Iceland plume is more enriched in the Pu-derived Xenon component. These features are interpreted as reflecting different degrees of outgassing and appear not to be the result of preferential recycling of Xenon to the deep mantle. To further investigate how representative the Icelandic measurements might be of other mantle plumes, we measured noble gases (He, Ne, Ar, Xe) in gas-rich basalt glasses from the Rochambeau Ridge (RR) in the Northern Lau Basin. Recent work suggests the presence of a "Samoan-like" OIB source in the northern Lau Basin and our measurements were performed on samples with plume-like 3He/4He ratios (15-28 RA) [1]. The Xenon isotopic measurements indicate that the maximum measured 136Xe/130Xe ratios in the Rochambeau samples are similar to Iceland. In particular, for one of the gas rich samples we were able to obtain 77 different isotopic measurements through step-crushing. Preliminary investigation of this sample suggests higher Pu- to U-derived fission Xenon than in MORBs. To quantitatively evaluate the degree and rate of outgassing of the plume and MORB reservoirs, particularly during the first few hundred million years of Earth's history, we have modified a geochemical reservoir model that was previously developed to investigate mantle overturn and mixing from He, Ar and lithophile isotopes [2]. We will present the results from this geochemical reservoirs model, which is constrained by our high precision dataset from the Rochambeau Rift (Northern Lau Basin) and Iceland along with the Xenon dataset from popping rock [3]. [1] Lupton et al., GRL, 2009. [2] Gonnermann and Mukhopadhyay, Nature, 2009. [3] Kunz et al., Science, 1998.

Peto, M. K.; Mukhopadhyay, S.; Kelley, K. A.

2011-12-01

75

[To the effective concentration of xenon].  

PubMed

The present literature discusses what effective concentration of xenon may be used to induce adequate anesthesia. To examine the analgesic properties of the substance, 38 patients undergone laparoscopic operations for calculous cholecystitis under informational saturation EEG (INEEG) monitoring were included into this study. All the patients were divided into 3 groups in accordance to the mode of anesthesia maintenance and INEEG monitoring. In Groups 1 and 2, the concentration of xenon was maintained at 70%; INEEG monitoring was made in the of-line mode. In Group 3, the concentration of xenon was gradually decreased from 70% to the minimum value at which the level of INEEG was 40-50%, which corresponds to the adequate depth of anesthesia. The use of 70% xenon concentration and the standard doses offentanyl (3.1 +/- 1.6 microg/kg/h) resulted in excessively deep anesthesia (38 +/- 4% INEEG). Reduction of the dose of fentanyl on an average to 1.5 +/- 0.8 microg/kg/h permitted more adequate anesthesia; however, an excessively deep anesthesia is encountered in 40% of cases, as evidenced by INEEG. The active use of INEEG monitoring in Group 3 makes it possible to perform an adequate anesthesia (46 +/- 4% INEEG) and to determine the xenon concentration necessary for this, which is equivalent to 42 +/- 11% with the dose of fentanyl of 0.9 +/- 0.8 microg/kg/h. PMID:15938090

Kazakov, E A; Subbotin, V V; Likhvantsev, V V; Sitnikov, A V

76

Pressurised xenon as scintillator for gamma spectroscopy  

NASA Astrophysics Data System (ADS)

Detectors based on liquid or gas xenon have been used and are in use for a number of applications, in particular for the detection of gamma rays. Xenon is a well-suited medium for gamma spectroscopy thanks to its high atomic number and, consequently, large cross-section for photo-electric absorption. This paper presents experimental studies of high pressure xenon as a scintillator, with the aim of developing a gamma ray detector for the detection of Special Nuclear Materials (SNM). The first goal was to study the dependence of the light yield and of the energy resolution on the thermodynamic conditions. We present preliminary results from an optimised version of the detector.

Resnati, F.

2013-09-01

77

Reflectance of polytetrafluoroethylene for xenon scintillation light  

SciTech Connect

Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region ({lambda}{approx_equal}175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.

Silva, C.; Pinto da Cunha, J.; Pereira, A.; Chepel, V.; Lopes, M. I.; Solovov, V.; Neves, F. [Department of Physics, LIP-Coimbra, University of Coimbra, P-3004 516 Coimbra (Portugal)

2010-03-15

78

Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal  

Microsoft Academic Search

We present constant-pressure Monte Carlo simulations of nuclear magnetic resonance (NMR) spectral parameters, nuclear magnetic shielding relative to the free atom as well as nuclear quadrupole coupling, for atomic xenon dissolved in a model thermotropic liquid crystal. The solvent is described by Gay-Berne (GB) molecules with parametrization kappa=4.4 , kappa'=20.0 , and mu=nu=1 . The reduced pressure of P*=2.0 is

Juho Lintuvuori; Michal Straka; Juha Vaara

2007-01-01

79

Photolabile xenon hydrides: A case study of HXeSH and HXeH  

NASA Astrophysics Data System (ADS)

The photo-induced transformations of HXeSH and HXeH under the action of IR and visible light have been studied using FTIR spectroscopy. The xenon hydrides were produced by the X-ray induced decomposition of H2S and its isotopomers in a solid xenon matrix at 7.5 K followed by thermal annealing at the temperatures up to 45 K. Selective IR-induced photodissociation of HXeSH at 3500-2500 cm-1 was attributed to vibrational excitation of the 3?H-Xe mode. The IR-photodecomposed HXeSH molecules can be almost quantitative recovered below 22 K with very small effective activation energy (~20 meV) indicating local character of this process. Analysis of the photoactivity of xenon hydrides in the visible region revealed previously unknown absorptions for HXeSH (in the region of 400-700 nm) and HXeH (above 700 nm). The decomposition of HXeH occurs due to both direct photolysis and reactions of ``hot'' H atoms produced from the photodissociation of HXeSH. The efficiency of thermal recovery for both xenon hydrides after photolysis with visible light was found to be dependent on the excitation wavelength, which was explained by the effect of photon energy on spatial distribution of the dissociation fragments.

Ryazantsev, Sergey V.; Kobzarenko, Alexey V.; Feldman, Vladimir I.

2013-09-01

80

Photolabile xenon hydrides: A case study of HXeSH and HXeH.  

PubMed

The photo-induced transformations of HXeSH and HXeH under the action of IR and visible light have been studied using FTIR spectroscopy. The xenon hydrides were produced by the X-ray induced decomposition of H2S and its isotopomers in a solid xenon matrix at 7.5 K followed by thermal annealing at the temperatures up to 45 K. Selective IR-induced photodissociation of HXeSH at 3500-2500 cm(-1) was attributed to vibrational excitation of the 3?H-Xe mode. The IR-photodecomposed HXeSH molecules can be almost quantitative recovered below 22 K with very small effective activation energy (?20 meV) indicating local character of this process. Analysis of the photoactivity of xenon hydrides in the visible region revealed previously unknown absorptions for HXeSH (in the region of 400-700 nm) and HXeH (above 700 nm). The decomposition of HXeH occurs due to both direct photolysis and reactions of "hot" H atoms produced from the photodissociation of HXeSH. The efficiency of thermal recovery for both xenon hydrides after photolysis with visible light was found to be dependent on the excitation wavelength, which was explained by the effect of photon energy on spatial distribution of the dissociation fragments. PMID:24089775

Ryazantsev, Sergey V; Kobzarenko, Alexey V; Feldman, Vladimir I

2013-09-28

81

Scintillation Light, Ionization Yield and Scintillation Decay Times in High Pressure Xenon and Xenon Methane  

Microsoft Academic Search

Scintillation light, ionization yield and scintillation decay times have been measured in xenon and in its mixture with a 0.05% concentration of methane as a function of the reduced electric field (E\\/N)-the ratio of the electric field strength to the number density of gas-at a pressure of 21 atm. The measurements of scintillation decay times in the xenon-methane mixture have

K. N. Pushkin; D. Y. Akimov; A. A. Burenkov; V. V. Dmitrenko; A. G. Kovalenko; V. N. Lebedenko; I. S. Kuznetsov; V. N. Stekhanov; C. Tezuka; S. E. Ulin; Z. M. Uteshev; K. F. Vlasik

2007-01-01

82

Atomistic study of stability of xenon nanoclusters in uranium oxide  

SciTech Connect

Density-functional theory calculations of the xenon incorporation energies in point defects in urania have been done in order to fit empirical potentials. With this set of parameters, we have considered the incorporation of xenon in small and extended defects such as planar interstitials, grain boundaries, faceted, and spherical voids. The results show that xenon atoms are more likely to aggregate than to be homogeneously distributed in the urania grains. SIGMA5 grain boundary and spherical shape voids are the most favorable defects of xenon atom incorporation. The presence of xenon atoms in nanovoids affects their shape. The energy gain to aggregate xenon atoms into clusters saturates for cluster sizes of about 15-20 Schottky defects. This demonstrates that medium size defects are just as favorable as big size defects for xenon incorporation.

Chartier, A.; Van Brutzel, L. [DEN, Service de Chimie Physique, CEA, F-91191 Gif-sur-Yvette (France); Freyss, M. [DEN, Service d'Etudes et de Simulation du Comportement des Combustibles, CEA, F-13108 Saint-Paul lez Durance (France)

2010-05-01

83

Diffusion of xenon (1); undecane (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Brnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) xenon; (2) undecane

Winkelmann, J.

84

Xenon Lighting Adjusted to Plant Requirements.  

National Technical Information Service (NTIS)

Xenon lamps are available as low and high power lamps with relatively high efficiency and a relatively long lifetime up to several thousand hours. Different construction types of short-arc and long-arc lamps permit a good adaptation to various application...

M. Koefferlein T. Doehring H. D. Payer H. K. Seidlitz

1994-01-01

85

Prospects for Barium Tagging in Gaseous Xenon  

Microsoft Academic Search

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the

D. Sinclair; E. Rollin; J. Smith; A. Mommers; N. Ackerman; B. Aharmim; M. Auger; P. S. Barbeau; C. Benitez-Medina; M. Breidenbach; A. Burenkov; S. Cook; A. Coppens; T. Daniels; R. DeVoe; A. Dobi; M. J. Dolinski; K. Donato; Fairbank W. Jr; J. Farine; G. Giroux

2012-01-01

86

Status of the solid xenon project at Fermilab  

NASA Astrophysics Data System (ADS)

The solid (crystalline) phase of xenon possesses many of the same advantages of liquid xenon as a particle detector material including good transparency and ionization drift, self-shielding, low intrinsic background, and high scintillation light yield. Many of the properties of solid xenon have been measured previously employing small volumes and thin films. However, few systematic studies have been successfully produced using large volumes of solid xenon. Two major R&D issues must be addressed to make a solid xenon particle detector; the demonstration of the scalability of solid xenon and the capability to readout solid xenon signals. Both issues are being addressed with a dedicated cryogenic system at Fermilab. The first phase of this project entailed growing approximately a kilogram of transparent solid phase xenon and was successfully completed in 2010 at Fermilab. The second phase of this project is underway where the signals from scintillation light and electron drift in solid xenon will be measured. These measurements are expected to be completed this year. In this talk, we will discuss the recent progress of solid xenon detector R&D performed at Fermilab.

Pahlka, R. B.

2013-09-01

87

Hyperpolarized xenon magnetic resonance of the lung and the brain  

NASA Astrophysics Data System (ADS)

Hyperpolarized noble gas Magnetic Resonance Imaging (MRI) is a new diagnostic modality that has been used successfully for lung imaging. Xenon is soluble in blood and inhaled xenon is transported to the brain via circulating blood. Xenon also accumulates in the lipid rich white matter of the brain. Hyperpolarized xenon can hence be used as a tissue- sensitive probe of brain function. The goals of this study were to identify the NMR resonances of xenon in the rat brain and evaluate the role of hyperpolarized xenon for brain MRI. We have developed systems to produce sufficient volumes of hyperpolarized xenon for in vivo brain experiments. The specialized instrumentation developed include an apparatus for optical pump-cell manufacture and high purity gas manifolds for filling cells. A hyperpolarized gas delivery system was designed to ventilate small animals with hyperpolarized xenon for transport to the brain. The T1 of xenon dissolved in blood indicates that the lifetime of xenon in the blood is sufficient for significant magnetization to be transferred to distal tissues. A variety of carrier agents for intravenous delivery of hyperpolarized xenon were tested for transport to distal tissues. Using our new gas delivery system, high SNR 129Xe images of rat lungs were obtained. Spectroscopy with hyperpolarized xenon indicated that xenon was transported from the lungs to the blood and tissues with intact magnetization. After preliminary studies that indicated the feasibility for in vivo rat brain studies, experiments were performed with adult rats and young rats with different stages of white matter development. Both in vivo and in vitro experiments showed the prominence of one peak from xenon in the rat brain, which was assigned to brain lipids. Cerebral brain perfusion was calculated from the wash-out of the hyperpolarized xenon signal in the brain. An increase in brain perfusion during maturation was observed. These experiments showed that hyperpolarized xenon MRI can be used to develop unique approaches to studying white matter and gray matter in the brain. Some of the possible applications of hyperpolarized xenon MRI in the brain are clinical diagnosis of white matter diseases, functional MRI (fMRI) and measurement of cerebral blood perfusion.

Venkatesh, Arvind Krishnamachari

2001-04-01

88

Optimization of xenon biosensors for detection of protein interactions.  

PubMed

Hyperpolarized 129Xe NMR spectroscopy can detect the presence of specific low-concentration biomolecular analytes by means of a xenon biosensor that consists of a water-soluble, targeted cryptophane-A cage that encapsulates the xenon. In this work, we use the prototypical biotinylated xenon biosensor to determine the relationship between the molecular composition of the xenon biosensor and the characteristics of protein-bound resonances. The effects of diastereomer overlap, dipole-dipole coupling, chemical-shift anisotropy, xenon exchange, and biosensor conformational exchange on the protein-bound biosensor signal were assessed. It was found that an optimal protein-bound biosensor signal can be obtained by minimizing the number of biosensor diastereomers and using a flexible linker of appropriate length. Both the line width and sensitivity of chemical shift to protein binding of the xenon biosensor were found to be inversely proportional to linker length. PMID:16342304

Lowery, Thomas J; Garcia, Sandra; Chavez, Lana; Ruiz, E Janette; Wu, Tom; Brotin, Thierry; Dutasta, Jean-Pierre; King, David S; Schultz, Peter G; Pines, Alex; Wemmer, David E

2006-01-01

89

The Large Underground Xenon (LUX) experiment  

NASA Astrophysics Data System (ADS)

The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles (WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross-section per nucleon of 210-46cm2, equivalent to 1event/100kg/month in the inner 100-kg fiducial volume (FV) of the 370-kg detector. The overall background goals are set to have <1 background events characterized as possible WIMPs in the FV in 300 days of running.This paper describes the design and construction of the LUX detector.

Akerib, D. S.; Bai, X.; Bedikian, S.; Bernard, E.; Bernstein, A.; Bolozdynya, A.; Bradley, A.; Byram, D.; Cahn, S. B.; Camp, C.; Carmona-Benitez, M. C.; Carr, D.; Chapman, J. J.; Chiller, A.; Chiller, C.; Clark, K.; Classen, T.; Coffey, T.; Curioni, A.; Dahl, E.; Dazeley, S.; de Viveiros, L.; Dobi, A.; Dragowsky, E.; Druszkiewicz, E.; Edwards, B.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gibson, K. R.; Gilchriese, M.; Hall, C.; Hanhardt, M.; Holbrook, B.; Ihm, M.; Jacobsen, R. G.; Kastens, L.; Kazkaz, K.; Knoche, R.; Kyre, S.; Kwong, J.; Lander, R.; Larsen, N. A.; Lee, C.; Leonard, D. S.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Lyashenko, A.; Malling, D. C.; Mannino, R.; Marquez, Z.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morii, M.; Nelson, H.; Neves, F.; Nikkel, J. A.; Pangilinan, M.; Parker, P. D.; Pease, E. K.; Pech, K.; Phelps, P.; Rodionov, A.; Roberts, P.; Shei, A.; Shutt, T.; Silva, C.; Skulski, W.; Solovov, V. N.; Sofka, C. J.; Sorensen, P.; Spaans, J.; Stiegler, T.; Stolp, D.; Svoboda, R.; Sweany, M.; Szydagis, M.; Taylor, D.; Thomson, J.; Tripathi, M.; Uvarov, S.; Verbus, J. R.; Walsh, N.; Webb, R.; White, D.; White, J. T.; Whitis, T. J.; Wlasenko, M.; Wolfs, F. L. H.; Woods, M.; Zhang, C.

2013-03-01

90

Cerebral blood flow tomography with xenon-133  

Microsoft Academic Search

Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-¹³³. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission computed tomograph (SPECT) is required. Two brain-dedicated SPECT systems designed for this

N LASSEN

1985-01-01

91

Controlled pulse-etching with xenon difluoride  

Microsoft Academic Search

A gas-phase, room-temperature, plasmaless isotropic etching system has been used for bulk and thin film silicon etching. A computer controlled multi-chambered etcher is used to provide precisely metered pulses of xenon difluoride (XeF2) gas to the etch chamber. Etch rates as high as 15 microns per minute have been observed. The etch appears to have infinite selectivity to many common

Patrick B. Chu; Jeffrey T. Chen; Richard Yeht; Gisela Lin; Jeff C. P. Huang; B. A. Warneke; S. J. Pister

1997-01-01

92

Prospects for Barium Tagging in Gaseous Xenon  

NASA Astrophysics Data System (ADS)

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.

Sinclair, D.; Rollin, E.; Smith, J.; Mommers, A.; Ackeran, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Cook, S.; Coppens, A.; Daniels, T.; DeVoe, R.; Dobi, A.; Dolinski, M. J.; Donato, K.; Fairbank, W., Jr.; Farine, J.; Giroux, G.; Gornea, G.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Kaufman, L. K.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLennan, R.; Mong, B.; Montero Dez, M.; Mller, A. R.; Neilson, R.; Niner, E.; Odian, A.; O'Sullivan, K.; Ouellet, C.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rowson, P. C.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-08-01

93

Xenon changes under power-burst conditions. [BWR  

SciTech Connect

Under ordinary operating conditions the xenon concentration in a reactor core can change significantly in times on the order of hours. Core transients of safety significance are much more rapid and hence calculations are done with xenon concentration held constant. However, in certain transients (such as reactivity initiated accidents) there is a very large power surge and the question arises as to whether under these circumstances the xenon concentration could change. This would be particularly important if the xenon were reduced thereby tending to make the accident autocatalytic. The objective of the present study is to quantify this effect to see if it could be important.

Diamond, D.J.

1983-01-01

94

A xenon ionization detector for digital radiography.  

PubMed

Xenon gas x-ray detectors have been used successfully in CT scanners; however, they have been found to be unsuitable for digital radiography. We have designed and built a new type of xenon x-ray detector array and tested its suitability for digital radiography. The detector consists of two parallel plates separated by a 0.5-mm gap, filled with xenon gas at a pressure of about 30 atm. One of the plates is the high-voltage electrode, while the other is a circuit board etched to form an array of metal collector strips focused on the x-ray source. Since there are no metal septa separating the individual detector elements, the dose efficiency of the detector is high, but image degradation will occur due to cross-talk between detector elements. Measurements of the cross-talk show that about an 18% reduction in contrast will occur, when a low contrast object, subtending one detector element, is imaged. We have also measured a detector MTF of 14% at 2 lp/mm, a signal of 10 pC for a 1-mR x-ray exposure at the detector entrance, a 6% nonlinearity in the detector signal over about 3 orders of magnitude in x-ray exposure, and a charge collection time (time response) of about 0.1 ms. From these results it is concluded that this new detector design is feasible for digital radiography. PMID:7087908

Drost, D J; Fenster, A

95

Method for the simultaneous preparation of Radon-211, Xenon-125, Xenon-123, Astatine-211, Iodine-125 and Iodine-123  

DOEpatents

A method for simultaneously preparing Radon-211, Astatine-211, Xenon-125, Xenon-123, Iodine-125 and Iodine-123 in a process that includes irradiating a fertile metal material then using a one-step chemical procedure to collect a first mixture of about equal amounts of Radon-211 and Xenon-125, and a separate second mixture of about equal amounts of Iodine-123 and Astatine-211.

Mirzadeh, Saed (East Setauket, NY); Lambrecht, Richard M. (Quogue, NY)

1987-01-01

96

Transient Xenon Analysis in a Molten Salt Breeder Reactor  

Microsoft Academic Search

An evaluation is made to estimate the transient xenon behavior in an MSBR for several representative patterns of operation. Such analysis is indispensable for detailed evaluation of reactivity balance under transient conditions. The results are compared with those of a typical PWR. The xenon behavior does not differ between the two types of reactor to the extent that might be

Yoichiro SHIMAZU

1977-01-01

97

Distillation purification and radon assay of liquid xenon  

SciTech Connect

We succeeded to reduce the Kr contamination in liquid xenon by a factor of 1/1000 with a distillation system in Kamioka mine. Then, the remaining radioactivities (Radon and Kr) in purified liquid xenon were measured with the XMASS prototype detector. In this talk, the distillation system and the remaining internal radioactivity levels are reported.

Takeuchi, Yasuo [Kamioka Observatory, ICRR, Univ. of Tokyo, Kamioka-cho, Hida-shi, Gifu 506-1205 (Japan)

2005-09-08

98

Xenon X-ray detector with tapered plates  

Microsoft Academic Search

The leading edge of the plates employed in a high pressure gaseous xenon x-ray detector are tapered so as to be narrower along the edge of the plates nearest to the x-ray source. Xenon x-ray detectors produced in accordance with the present invention exhibit an increased quantum detection efficiency without a significant increase in noise due to microphonics.

1984-01-01

99

Xenon as a detector for dark matter search.  

NASA Astrophysics Data System (ADS)

The author discusses the detailed properties of xenon and its utilization for detecting weakly interacting massive particles (WIMPs). Xenon scintillation and proportional scintillation are the key factors in the problem of background rejection. He also considers the possibility of doping liquid Xe with triethylamine (TEA), to lower the energy threshold and to improve background rejection efficiency.

Wang, Hanguo

1998-12-01

100

Generation of alkoxide anions from a series of aliphatic diols and alcohols and their ion-molecule reactions with carbon dioxide in the gas phase.  

PubMed

Alkoxide anions, [M-H](-) from a series of aliphatic diols and alcohols are generated in the source under negative ion electrospray ionisation conditions by cone-voltage fragmentation of the corresponding [M + F](-) ions. The collision-induced dissociation (CID) spectra of [M-H](-) ions consist of [M-H-2H](-) ions, in addition to the other characteristic fragment ions, and the relative abundance of [M-H-2H(-) ions among the series of diols varies as a function of chain length that could be explained based on their stabilities through intramolecular hydrogen bonding. The reactivity of alkoxide anions is studied through ion-molecule reactions with CO(2) in the collision cell of a triple quadrupole mass spectrometer. All the alkoxide anions reacted with CO(2) and formed corresponding carbonate anions, [M-H + CO(2)](-) ions. The reactivity of alkoxide anions within the series of diols also reflected the stability of their [M-H](-) ions. PMID:16531646

Kumar, M Ravi; Prabhakar, S; Reddy, T Jagadeshwar; Vairamani, M

2006-01-01

101

A xenon gas purity monitor for EXO  

NASA Astrophysics Data System (ADS)

We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.

Dobi, A.; Hall, C.; Herrin, S.; Odian, A.; Prescott, C. Y.; Rowson, P. C.; Ackerman, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Barry, K.; Benitez-Medina, C.; Breidenbach, M.; Cook, S.; Counts, I.; Daniels, T.; DeVoe, R.; Dolinski, M. J.; Donato, K.; Fairbank, W.; Farine, J.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, K.; Hallman, D.; Hargrove, C.; Karelin, A.; Kaufman, L. J.; Kuchenkov, A.; Kumar, K.; Lacey, J.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLellan, R.; Mong, B.; Montero Dez, M.; Mller, A. R.; Neilson, R.; Niner, E.; O'Sullivan, K.; Piepke, A.; Pocar, A.; Pushkin, K.; Rollin, E.; Sinclair, D.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-12-01

102

Environmental application of stable xenon and radioxenonmonitoring  

SciTech Connect

Characterization of transuranic waste is needed to makedecisions about waste site remediation. Soil-gas sampling for xenonisotopes can be used to define the locations of spent fuel andtransuranic wastes. Radioxenon in the subsurface is characteristic oftransuranic waste and can be measured with extreme sensitivity usinglarge-volume soilgas samples. Measurements at the Hanford Site showed133Xe and 135Xe levels indicative of 240Pu spontaneous fission. Stablexenon isotopic ratios from fission are distinct from atmospheric xenonbackground. Neutron capture by 135Xe produces an excess of 136Xe inreactor-produced xenon providing a means of distinguishing spent fuelfrom separated transuranic materials.

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre,Justin I.; Waichler, Scott R.; Milbrath, Brian D.; Cooper, Matt; Kennedy,B. Mack

2006-09-05

103

Solubilities of krypton and xenon in dichlorodifluoromethane  

SciTech Connect

The solubility behavior of krypton and xenon in dichlorodifluoromethane was investigated for the Consolidated Fuel Reprocessing Program (CFRP) in support of the fluorocarbon absorption process. The solubility data derived from solute radioisotopes had uncertainties of approx. 0.1%. Values for Henry's law constants were initially determined under equilibrium conditions at infinite solute dilution. Based on these results, the study was extended to finite solute concentrations. Nonidealities in the two binary systems were expressed as gas phase fugacity coefficients for each solute at 10/sup 0/ intervals over the range -30 to +50/sup 0/C. 22 references, 4 figures, 2 tables.

Shaffer, J.H.; Shockley, W.E.; Greene, C.W.

1984-07-01

104

Xenon recirculation systems for next-generation lithography tools  

NASA Astrophysics Data System (ADS)

Next generation lithography tools designed to pattern critical dimensions at <45nm will require extreme ultraviolet (EUV) light sources. Xenon is currently a strong candidate for the source medium for production of EUV light at 13.5nm. A consistent supply of ultra high purity xenon is required for efficient light source production. Several factors must be considered in the overall operating costs of the EUV tool: The high cost of xenon (typically ~$4/litre); The quantities required for EUV source production, which are typically 4slpm for Laser Produced Plasma (LPP) and 300sccm for Gas Discharge Produced Plasma (GDPP). On the basis of these figures the annual xenon cost would typically be approximately $11M/year for LPP, $1M/year for GDPP. Therefore recycling of xenon offers a significant operating cost reduction. This type of re-circulation system is not restricted to high xenon throughput applications, but can be scaled in size, and hence cost, for application to lower throughput process applications. Additional applications in mainstream silicon processing including a new development in dielectric etch using xenon could also benefit from re-circulation. Present research indicates that for a typical recipe, 675sccm xenon is required per wafer pass, this equates to an annual cost of $0.6M. BOC Edwards has designed & built a series of five fully integrated xenon re-circulation systems for lithography applications. Each system has been custom designed to exact application requirements, including liquid/solid xenon filament production. Additionally, an important footprint reduction has been achieved during the design evolution, which ideally suits dielectric etch applications.

Greenwood, Joanne R.; Mennie, Darren; Hughes, Carolyn; Lee, Ron

2004-05-01

105

METEORITIC KRYPTON AND BARIUM VERSUS THE GENERAL ISOTOPIC ANOMALIES IN METEORITIC XENON  

Microsoft Academic Search

General isotopic anomalies in meteoritic xenon are described in detail. ; Where superior isotopic analyses exist, the xenon anomalies appear to be the same ; for all meteorites. In other cases there is fair evidence that the xenon ; examined is a mixture of meteoritic and contaminating atmospheric xenon. Two ; superior krypton analyses for carbonaceous chondrites show no anomalies

D. Krummenacher; C. M. Merrihue; R. O. Pepin; J. H. Reynolds

1962-01-01

106

NMR study of xenon dynamics and energetics in NaA zeolite  

Microsoft Academic Search

For xenon atoms adsorbed in Na-A xeolite, electronic interactions cause shifts in NMR frequencies, resulting in a spectrum with discrete peaks from xenon atoms in cages with different xenon occupancies. Using two-dimensional exchange NMR, it is possible to determine the microscopic rates of intercage motion and to relate them to the adsorption and activation energies of the xenon atoms. The

R. G. Larsen; J. Shore; K. Schmidt-Rohr; L. Emsley; H. Long; A. Pines; M. Janicke; B. F. Chmelka

1993-01-01

107

Xenon changes under power burst conditions  

SciTech Connect

Following the accident at the Chernobyl reactor, the U.S. Nuclear Regulatory Commission (NRC) initiated a study of the potential for reactivity accidents in U.S. light water reactors. As a part of that study, autocatalytic power excursions were examined. Some of these had been determined previously to be unimportant because judgments had been made that they could not lead to serious consequences or that they had too low a probability to be taken seriously. The intent of the study was to do more quantitative analysis to see if these judgments could be reconfirmed. As a result of these calculations, it is clear that it is not possible for a power burst to become autocatalytic due to the burnout of xenon. The power required to do this would be so high that core damage would result independently of the burnout of the xenon. Although this result was known intuitively, the simple analytical model derived herein has allowed this to be confirmed quantitatively.

Diamond, D.J. (Brookhaven National Laboratory, Upton, NY (USA))

1989-11-01

108

Potential ocular hazards from xenon flashlamps.  

PubMed

High radiance optical sources used in fast photocopiers represent a potential hazard to the human retina. Primates (macaque monkeys) were exposed to a prototype flashtube assembly similar to that used in fast photocopiers. One animal trained in a restraint chair to perform a visual task for a major portion of his food was exposed to multiple pulses (1000 pulses daily) from two xenon flashtubes placed 22 cm from the eyes. After sixty daily exposures over a period of three months with pupils dilated to 8 mm or greater, no anomalies were detectable in the retina. Examination for defects with the fundus camera was negative even a year after the exposures. Four additional monkeys (eight eyes) were exposed under anesthesia to insure that repetitive exposures on the retina were coincident. Exposure to two xenon flashtubes, each with 160-J input, did not produce a retinal lesion after 4200 flashes spaced 1.7 s apart. Exposure to a single flashtube with 540-J input produced negative results even after fifty flashes focused on the same retinal site. It was concluded that neither of these optical sources was capable of producing a thermal lesion in the monkey retina. Calculations predict that a photochemical-type retinal lesion is possible but only in extraordinary conditions of exposure which would be extremely unlikely, if not impossible, while viewing a photocopier. PMID:20490083

Ham, W T; Mueller, H A; Ely, T S

1987-08-15

109

PIXeY - Liquid Xenon R&D at Yale  

NASA Astrophysics Data System (ADS)

In recent years xenon has risen as a medium for particle detection, exhibiting a number of desirable qualities that make it well-suited for applications such as medical imaging, imaging of nuclear materials, and fundamental physics research. Xenon is a bright scintillator, with a fast (45 ns) response time, a large charge yield and high electron mobility. The high density (3 g/mL) and high atomic number (Z = 54) of liquid xenon make it ideal for detecting gamma rays with high efficiency over large energy ranges. PIXeY (Particle Identification in Xenon at Yale) is a compact, liquid-xenon-based TPC that operates in either single or two-phase (liquid/gas) mode and detects both charge and light signals produced by particle interactions within the detector. The initial goal of the experiment is to study xenon physics with implications for the operation and design for future large scale experiments (for dark matter or double beta decay), including energy resolution and event discrimination. This presentation will provide an overview of the experiment and discuss the xenon physics studies planned, the results so far and a brief overview of future plans.

Edwards, Blair; Bernard, Ethan; Cahn, Sidney; Larsen, Nicole; Lyashenko, Alexey; McKinsey, Daniel; Nikkel, James; Shin, Yunchang; Tennyson, Brian; Wahl, Christopher; Destefano, Nicholas; Gai, Moshe

2013-04-01

110

Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis  

SciTech Connect

The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

Nelson, Andrew T. [Los Alamos National Laboratory

2012-08-30

111

Environmental Applications of Stable Xenon and Radioxenon Monitoring  

SciTech Connect

Improved detection capabilities are needed at several Department of Energy sites to make remedial decisions about facilities and landfill cleanup. For facility monitoring air samples can be collected from within a facility and analyzed for short lived radioxenons to estimate inventories of residual plutonium holdup within the facility. For landfill cleanup activities soil gas sampling for xenon isotopes can be used to define the locations of spent fuel and transuranic wastes. Short-lived radioxenon isotopes are continuously produced by spontaneous fission of plutonium-240 in transuranic wastes. Large volume soil-gas samples provide extremely sensitive measurement of radioxenon in the subsurface; a characteristic of transuranic waste. The analysis employs a modified Automated Radioxenon Sampling and Analysis (ARSA) system. Proof of principle measurements at a Hanford Site liquid waste disposal site showed xenon-133 at levels in soil gas are approximately 16,000 times the detection limit and lower levels of xenon-135 from the spontaneous fission of plutonium-240 were also measured. Stable xenon isotopes are also produced by spontaneous fission but are subject to background concentrations in ambient air samples (facilities) but less so in soil gas where free exchange with ambient air is restricted. Rare gas mass spectrometry is used for highly precise stable xenon isotopic measurements. Stable xenon isotopic ratios from fission are distinct from natural xenon background ratios. Neutron capture on xenon-135 produces an excess of xenon-136 above fission ratios and thus provides a means of distinguishing reactor sources (e.g. spent fuel) from separated transuranic materials (plutonium).

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre, Justin I.; Waichler, Scott R.; Kennedy, B. M.

2008-06-01

112

Cryopumping system for tests of xenon ion thrusters  

SciTech Connect

A cryopumping system suitable for testing xenon ion thrusters was designed and tested. The aimed temperature of a CP (cryopanel) was below 50 K, since the vapor pressure of xenon was low enough at the temperature. The system-alone-tests showed the attained temperature of the CP was below 50 K and the CP could evacuate xenon with a pumping speed of over 600,000 l/s. But while an ion thruster was operating, the speed fell to 40,000 l/s and a continuous operational time was restricted to about 90 minutes.

Hayakawa, Y.; Kitamura, S.; Nakamura, Y.; Miyazaki, K.; Obama, T.

1987-01-01

113

Pulse Shape in 2-Phase Xenon Detectors  

NASA Astrophysics Data System (ADS)

Understanding the shape and size of the primary (S1) and secondary (S2) scintillation pulses in noble elements is crucial for discriminating between different particle interactions. Monte Carlo results from NEST (the Noble Element Simulation Technique) will be presented which match the available data from liquid xenon on the dependence of the recombination time, which is a critical piece of the S1 pulse timing structure, on dE/dx, interaction type, and electric field magnitude. In addition, a model for the S2 pulse shape and the dependence of its width on the depth of an interaction in a detector will be presented which takes into account drift speed, the single/triplet time constants, diffusion, thermal electron trapping at a liquid-gas interface, and other effects.

Mock, Jeremy

2013-04-01

114

Dielectronic recombination cross sections of neonlike xenon  

SciTech Connect

High-resolution measurements of dielectronic recombination cross sections for neonlike xenon (Xe{sup 44+}) are presented. The experimental method consists of the formation and interaction of ions with electrons in an ion trap followed by an analysis of the extracted ions to determine relative yields. Low beam currents are used to obtain an energy resolution of 16 eV FWHM. Reductions in the number of initial ions of more than 3 orders of magnitude are observed as the strongest resonances are scanned. The relative contributions of the {ital LMM}, {ital LMN}, {ital LMO}, {ital LMP}, and {ital LMQ} groups of resonances are compared to theoretical calculations. The agreement with theory is excellent.

DeWitt, D.R.; Schneider, D.; Chen, M.H.; Clark, M.W.; McDonald, J.W.; Schneider, M.B. (Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States))

1992-03-16

115

Fluorination of amorphous thin-film materials with xenon fluoride  

DOEpatents

A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

Weil, R.B.

1987-05-01

116

Lung Surface Area Measurements Using Polarized Xenon NMR  

NASA Astrophysics Data System (ADS)

We are using laser-polarized xenon NMR to image the exchange of xenon from the lung gas space into solution in the alveolar tissue lining. The short-time rate of such xenon exchange depends on the surface area of the interface between the dissolved and gas phases. Hence xenon interphase exchange NMR will provide a non-invasive means to map the surface area of the lung. Since the function of the lung is to exchange gases between the bloodstream and the air, and the effectiveness of this gas exchange depends critically on the surface area of contact between blood-filled lung tissue and gas, our measurements will comprise imaging of lung function. This technique could be a powerful new tool for disease diagnosis and fundamental physiological research.

Hoffman, D.; Mair, R. W.; Walsworth, R. L.; Butler, J. P.; Patz, S.; Topulos, G. P.

1999-03-01

117

Plutonium-244 fission xenon in the most primitive meteorites.  

NASA Astrophysics Data System (ADS)

The plutonium-244/xenon-136 ages of the Murchison, Murray and Orgueil meteorites have been calculated from the existing xenon isotope data and the uranium contents. The CI carbonaceous chondrite Orgueil, which is considered to be among the most primitive - in the sense of the least altered - sample of the solar system known to man, appears to have started to retain its xenon more than 5,000 million years ago, when the ratio of 244Pu to 238U in the solar system was as high as (0.50.1) (atom/atom) and the CM carbonaceous chondrites Murchison and Murray started to retain their xenon about 4,940 million years ago, when the 244Pu to 238U ratio was about 0.17 (atom/atom).

Kuroda, P. K.; Myers, W. A.

118

Fluorination of amorphous thin-film materials with xenon fluoride  

DOEpatents

A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

Weil, Raoul B. (Haifa, IL)

1988-01-01

119

Stark Widths Of Ionized Xenon UV Lines Of Low Intensity  

SciTech Connect

Stark width measurements of several low intensity Xe II spectral lines (5d - 4f transitions) in UV region, are presented here for the first time. These measurements were obtained from helium - xenon pulsed arc plasma.

Cirisan, M.; Djurovic, S. [Faculty of Sciences, Department of Physics, Trg Dositeja Obradovica 4, 21000 Novi Sad (Serbia); Pelaez, R. J.; Aparicio, J. A.; Mar, S. [Departamento de Fisica Teorica Atomica y Optica, Facultad de Ciencias, Universidad de Valladolid, P. Prado de la Magdalena s/n, 47071 Valladolid (Spain)

2007-04-23

120

Determination of time-course change rate for arterial xenon using the time course of tissue xenon concentration in xenon-enhanced computed tomography  

SciTech Connect

In calculating tissue blood flow (TBF) according to the Fick principle, time-course information on arterial tracer concentration is indispensable and has a considerable influence on the accuracy of calculated TBF. In TBF measurement by xenon-enhanced computed tomography (Xe-CT), nonradioactive xenon gas is administered by inhalation as a tracer, and end-tidal xenon is used as a substitute for arterial xenon. There has been the assumption that the time-course change rate for end-tidal xenon concentration (Ke) and that for arterial xenon concentration (Ka) are substantially equal. Respiratory gas sampling is noninvasive to the patient and Ke can be easily measured by exponential curve fitting to end-tidal xenon concentrations. However, it is pointed out that there would be a large difference between Ke and Ka in many cases. The purpose of this work was to develop a method of determining the Ka value using the time course of tissue xenon concentration in Xe-CT. The authors incorporated Ka into the Kety autoradiographic equation as a parameter to be solved, and developed a method of least-squares to obtain the solution for Ka from the time-course changes in xenon concentration in the tissue. The authors applied this method of least-squares to the data from Xe-CT abdominal studies performed on 17 patients; the solution for Ka was found pixel by pixel in the spleen, and its Ka map was created for each patient. On the one hand, the authors obtained the average value of the Ka map of the spleen as the calculated Ka (Ka{sub calc}) for each patient. On the other hand, the authors measured Ka (Ka{sub meas}) using the time-course changes in CT enhancement in the abdominal aorta for each patient. There was a good correlation between Ka{sub calc} and Ka{sub meas} (r=0.966, P<0.0001), and these two Ka values were close to each other (Ka{sub calc}=0.935xKa{sub meas}+0.089). This demonstrates that Ka{sub calc} would be close to the true Ka value. Accuracy of TBF by Xe-CT can be improved with use of the average value of the Ka map of an organ like the spleen that has a single blood supply (only arterial inflow)

Sase, Shigeru; Takahashi, Hideaki; Ikeda, Hiroki; Kobayashi, Minoru; Matsumoto, Nobuyuki; Suzuki, Michihiro [Anzai Medical Co., Ltd., 3-9-15 Nishi-Shinagawa, Shinagawa-ku, Tokyo 141-0033 (Japan); Department of Internal Medicine, Division of Gastroenterology and Hepatology, School of Medicine, St. Marianna University, 2-16-1 Miyamae-ku, Sugao, Kawasaki 216-5811 (Japan)

2008-06-15

121

Xenon liquid-jet laser plasma source for EUV lithography  

NASA Astrophysics Data System (ADS)

We describe a laser-plasma source based on a cryogenic xenon liquid-jet target suitable for extreme ultraviolet (EUV) projection lithography. Recent improvements in the stability of the xenon jet allows efficient laser-plasma operation several millimeters away from the nozzle orifice. We present the first preliminary laser-to-EUV conversion efficiencies, although under non-optimized conditions, for the source.

Hansson, Bjoern A.; Berglund, Magnus; Hemberg, Oscar; Hertz, Hans M.

2000-07-01

122

Neuroprotective and neurotoxic properties of the 'inert' gas, xenon  

Microsoft Academic Search

Background. Antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate recep- tors have been shown not only to have neuroprotective effects but also to exhibit neurotoxic properties. In this study, we used c-Fos, a protein product of an immediate early gene, as a marker of neuronal injury to compare the neuroprotective effects of xenon and the neurotoxic properties of xenon, nitrous

D. Ma; S. Wilhelm; M. Maze; N. P. Franks

2002-01-01

123

High-pressure xenon detectors for gamma-ray spectrometry  

Microsoft Academic Search

The main results of long-term research on compressed xenon detector properties conducted at the laboratory of cosmic physics of MEPhI are given along with a description of the latest gamma-ray spectrometers based on this work. It is shown that using xenon as working substance, it is possible to create a gamma-ray spectrometer with high energy resolution. The construction and the

V. V. Dmitrenko; V. M. Gratchev; S. E. Ulin; Z. M. Uteshev; K. F. VIasik

2000-01-01

124

A cold low noise preamplifier for use in Liquid Xenon  

Microsoft Academic Search

In this paper a low-noise preamplifier for liquid- xenon ionization detectors is presented. The preamplifier has a cold front-end to be operated in liquid xenon at ~160 K and a warm part installed 15-cm apart and working at room temperature. It features an unusually high sensitivity of ~70 mV\\/fC. This specification is required because the net charge delivered in liquid

A. Pullia; F. Zocca; U. Oberlack; C. Olsen; P. Shagin

2007-01-01

125

Carbon dioxide  

NSDL National Science Digital Library

Bubbles are an indicator of a chemical reaction. An indicator is an object, material, or organism that tells you if a specific substance is present. In the sugar test, carbon dioxide gas release is an indicator that yeast is using sugar to grow. The more gas produced, the more sugar a specific substance contains.

Arie Melamed-Katz (None;)

2007-06-19

126

Hyperpolarized xenon NMR and MRI signal amplification by gas extraction  

PubMed Central

A method is reported for enhancing the sensitivity of NMR of dissolved xenon by detecting the signal after extraction to the gas phase. We demonstrate hyperpolarized xenon signal amplification by gas extraction (Hyper-SAGE) in both NMR spectra and magnetic resonance images with time-of-flight information. Hyper-SAGE takes advantage of a change in physical phase to increase the density of polarized gas in the detection coil. At equilibrium, the concentration of gas-phase xenon is ?10 times higher than that of the dissolved-phase gas. After extraction the xenon density can be further increased by several orders of magnitude by compression and/or liquefaction. Additionally, being a remote detection technique, the Hyper-SAGE effect is further enhanced in situations where the sample of interest would occupy only a small proportion of the traditional NMR receiver. Coupled with targeted xenon biosensors, Hyper-SAGE offers another path to highly sensitive molecular imaging of specific cell markers by detection of exhaled xenon gas.

Zhou, Xin; Graziani, Dominic; Pines, Alexander

2009-01-01

127

Relativistic Calculations of Electron Ionization of Xenon  

NASA Astrophysics Data System (ADS)

We are interested in the ionization of heavy atoms by electrons of intermediate energy. Since the incident particles do not have relativistic energies, the question arises as to why a relativistic treatment of this process is preferable. The answer lies both in the treatment of the target as well as the incident particle. In our case, a relativistic treatment of the target system is done within the j-j coupling scheme where the spin and angular momenta of each electron are coupled to a total angular momentum j. Thus the valence p shell of xenon is split into two subshells, one with j = 3/2 and one with j = 1/2. Calculations of the target wave functions can be readily carried out using an available program [1]. There is a fine structure splitting of 1.31 eV between these two subshells. Thus the energy required to ionize these two subshells is sufficiently different that they can be distinguished experimentally. The Dirac equations which describe the free electrons in a distorted-wave approximation with non-local exchange explicitly contain the spin of the electron. Thus the treatment of spin-polarized scattering is straightforward and does not require any recoupling of angular momenta as in a non-relativistic scheme. Recent experiments [2,3] have measured the ionization of the j = 3/2 valence electrons of xenon when the incident electron makes an arbitrary angle with the plane containing the outgoing electron which have identical energies. We will present calculations for this process to compare with the measurements and discuss the results in terms of the models proposed for the scattering mechanisms giving rise to these non-coplanar events.[4pt] [1] P. Jonsson, X. He, C. Froese Fischer and I. P. Grant, Comput. Phys. Commun. 177, 597-622 (2007).[0pt] [2] K. L. Nixon, A. J. Murray and C. Kaiser, J. Phys. B 43, 085202 (2010).[0pt] [3] K. L. Nixon and A. J. Murray, Phys. Rev. A 85, 022716 (2012).

Stauffer, Allan

2012-10-01

128

Luminescence evidence for bulk and surface excitons in free xenon clusters  

SciTech Connect

The cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying the initial experimental parameters, including the xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters ({approx_equal}1500 atoms). The cluster size and temperature ({approx_equal}40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. The presence of an argon shell causes extinction of the excitonic bands. In addition, some bands were found which have no analogs for bulk xenon cryosamples.

Danylchenko, O. G.; Doronin, Yu. S.; Kovalenko, S. I.; Libin, M. Yu.; Samovarov, V. N.; Vakula, V. L. [B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Avenue, Kharkiv, 61103 (Ukraine)

2007-10-15

129

Optimization of Xenon Difluoride Vapor Delivery  

SciTech Connect

Xenon difluoride (XeF{sub 2}) has been shown to provide many process benefits when used as a daily maintenance recipe for ion implant. Regularly flowing XeF{sub 2} into the ion source cleans the deposits generated by ion source operation. As a result, significant increases in productivity have been demonstrated. However, XeF{sub 2} is a toxic oxidizer that must be handled appropriately. Furthermore, it is a low vapor pressure solid under standard conditions ({approx}4.5 torr at 25 deg. C). These aspects present unique challenges for designing a package for delivering the chemistry to an ion implanter. To address these challenges, ATMI designed a high-performance, re-usable cylinder for dispensing XeF{sub 2} in an efficient and reliable manner. Data are presented showing specific attributes of the cylinder, such as the importance of internal heat transfer media and the cylinder valve size. The impact of mass flow controller (MFC) selection and ion source tube design on the flow rate of XeF{sub 2} are also discussed. Finally, cylinder release rate data are provided.

Sweeney, Joseph; Marganski, Paul; Kaim, Robert; Wodjenski, Mike; Gregg, John; Yedave, Sharad; Sergi, Steve; Bishop, Steve; Eldridge, David; Zou Peng [ATMI, Inc., Danbury, Connecticut 06810 (United States)

2008-11-03

130

Converging xenon shock waves driven by megagauss magnetic fields  

SciTech Connect

We attempted to implode a conducting metal linear at high velocity, and our failure to do so led to switching, or rapidly transferring the field from pushing an aluminum conductor to snow-plowing a half-atmosphere of xenon gas. We successfully initiated convergent xenon gas shocks with the use of a magnetohydrodynamic switch and coaxial high-explosive, flux-compression generators. Principal diagnostics used to study the imploding xenon gas were /sup 133/Xe radioactive tracers, continuous x-ray absorption, and neutron output. We compressed the xenon gas about five to sixfold at a velocity of 10 cm/..mu..s at a radius of 4 cm. The snowplow efficiency was good; going from 13- to 4-cm radius, we lost only about 20% of the mass. The temperature of the imploded sheath was determined by mixing deuterium with the xenon and measuring the neutron output. Using reasonable assumptions about the amount, density, and uniformity of the compressed gas, we estimate that we reached temperatures as high as 155 eV. Energy-loss mechanisms that we encountered included wall ablation and Taylor instabilities of the back surface.

Shearer, J.W.; Steinberg, D.J.

1986-07-01

131

Modeling Xenon Purification Systems in a Laser Inertial Fusion Engine  

NASA Astrophysics Data System (ADS)

A Laser Inertial Fusion Engine (LIFE) is a proposed method to employ fusion energy to produce electricity for consumers. However, before it can be built and used as such, each aspect of a LIFE power plant must first be meticulously planned. We are in the process of developing and perfecting models for an exhaust processing and fuel recovery system. Such a system is especially essential because it must be able to recapture and purify expensive materials involved in the reaction so they may be reused. One such material is xenon, which is to be used as an intervention gas in the target chamber. Using Aspen HYSYS, we have modeled several subsystems for exhaust processing, including a subsystem for xenon recovery and purification. After removing hydrogen isotopes using lithium bubblers, we propose to use cryogenic distillation to purify the xenon from remaining contaminants. Aspen HYSYS allows us to analyze predicted flow rates, temperatures, pressures, and compositions within almost all areas of the xenon purification system. Through use of Aspen models, we hope to establish that we can use xenon in LIFE efficiently and in a practical manner.

Hopkins, Ann; Gentile, Charles

2011-11-01

132

Xenon Anesthesia Improves Respiratory Gas Exchanges in Morbidly Obese Patients  

PubMed Central

Background. Xenon-in-oxygen is a high density gas mixture and may improve PaO2/FiO2 ratio in morbidly obese patients uniforming distribution of ventilation during anesthesia. Methods. We compared xenon versus sevoflurane anesthesia in twenty adult morbidly obese patients (BMI > 35) candidate for roux-en-Y laparoscopic gastric bypass and assessed PaO2/FiO2 ratio at baseline, at 15?min from induction of anaesthesia and every 60?min during surgery. Differences in intraoperative and postoperative data including heart rate, systolic and diastolic pressure, oxygen saturation, plateau pressure, eyes opening and extubation time, Aldrete score on arrival to the PACU were compared by the Mann-Whitney test and were considered as secondary aims. Moreover the occurrence of side effects and postoperative analgesic demand were assessed. Results. In xenon group PaO2-FiO2 ratio was significantly higher after 60?min and 120?min from induction of anesthesia; heart rate and overall remifentanil consumption were lower; the eyes opening time and the extubation time were shorter; morphine consumption at 72?hours was lower; postoperative nausea was more common. Conclusions. Xenon anesthesia improved PaO2/FiO2 ratio and maintained its distinctive rapid recovery times and cardiovascular stability. A reduction of opioid consumption during and after surgery and an increased incidence of PONV were also observed in xenon group.

Abramo, Antonio; Di Salvo, Claudio; Foltran, Francesca; Forfori, Francesco; Anselmino, Marco; Giunta, Francesco

2010-01-01

133

The krypton and xenon markets up to the year 2000  

NASA Astrophysics Data System (ADS)

Krypton and xenon are rare gases which are found in air in concentrations of about 1.14 and 0.087 ppm, respectively. They are produced in specially equipped, very large air separation units by adding a special raw gas extraction unit. Then this raw gas is purified and the krypton and xenon are separated by cryogenic methods. These rare gases are used in the lamp industry, for medical applications and in laser and research applications. The market for krypton and xenon is growing. The production capacity for these gases is limited and this results in a cyclic behavior of availability and market price. In the next few years, 10-20 million liters of krypton and one to two million liters of xenon will become available on the market due to new investments in the USA, South Africa and the AGA AB joint venture in the USSR. The total world production capacity of krypton and xenon will increase to 60-80 million liters. To influence the availability of these gases it is important to have close partnership between user and producer, which will realize bright and unorthodox ideas for the supply and use of these rare gases. Marketing Manager of AGA AB

Hammarlund, Nils

1992-05-01

134

Hugoniot measurements of double-shocked precompressed dense xenon plasmas.  

PubMed

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ?6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures. PMID:23368058

Zheng, J; Chen, Q F; Gu, Y J; Chen, Z Y

2012-12-12

135

Hugoniot measurements of double-shocked precompressed dense xenon plasmas  

NASA Astrophysics Data System (ADS)

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to 6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

2012-12-01

136

Axial Xenon Oscillation Analysis basing on a Coupled Code and a Simplified Code  

Microsoft Academic Search

Xenon-135 is the fission production, which can lead to the xenon spatial concentration distribution period oscillation with time in the thermal neutron reactors. The period of xenon oscillation is about 20 hr. Xenon oscillation is a three-dimension space-time problem, which is stimulated by the reactivity perturbation, for some of the control rods malfunction or operators' mistakes. And the power spatial

Lin Faxiong; Cao Xinrong

2010-01-01

137

Cold Ion-Molecule Chemistry with a Stark Decelerator Beamline  

NASA Astrophysics Data System (ADS)

We describe an experimental method for studying ion-molecule reactive collisions at very low energies. Building on our previous work using an electrostatic quadrupole guide as a source of cold neutral molecules, we discuss a proof of principle study of the charge-exchange reaction between cold xenon ions and Stark decelerated ammonia molecules. Ammonia molecules from a pulsed supersonic expansion are produced at low velocities using the Stark deceleration technique of Meijer and co-workers. The decelerated molecules are focussed using pulsed electrostatic hexapoles into the centre of a radiofrequency ion trap where they collide with cold xenon ions. A fast-opening vacuum-compatible mechanical shutter installed in the beamline is used to prevent transmission of the undecelerated molecules and carrier gas into the ion trap chamber. To prepare the target ions, the ion trap is loaded with calcium ions, which are Doppler laser cooled to form a low-temperature ordered ``Coulomb crystal'' phase. Xenon ions formed by resonant multiphoton ionisation are subsequently loaded and sympathetically cooled through their Coulomb interaction with the laser-cooled ions. The spatial distribution of fluorescence emitted by the laser-cooled ions in the multicomponent crystal is imaged; reactive collisions of Xe^+ with ND_3 are observed and quantified through changes in this distribution. By varying the high voltage switching sequence applied to the decelerator, the velocity of the ammonia molecules can be tuned from around 250 m/s to 35 m/s. For collisions with trapped xenon ions, this corresponds to collision energies (expressed in temperature units) from 65 K down to close to 1 K.

Oldham, James M.; Bell, Martin T.; Harper, Lee D.; Softley, Timothy P.

2012-06-01

138

High-field NMR of adsorbed xenon polarized by laser pumping  

Microsoft Academic Search

Optical pumping has been used to enhance the pulsed NMR signal of 129Xe, allowing the detecting of low-pressure xenon gas and of xenon adsorbed on powdered solids. We observe an increase in sensitivity of more than 2 orders of magnitude over conventional NMR, the current limitation being the laser power. Adsorbed xenon is observed at 298 K on graphitized carbon

D. Raftery; H. Long; T. Meersmann; P. J. Grandinetti; L. Reven; A. Pines

1991-01-01

139

Mass transfer of helium, neon, argon, and xenon through a steady-state upper mantle  

Microsoft Academic Search

We have examined the steady-state upper mantle model for helium, neon, argon, and xenon following the mass transfer approach presented by Kellogg and Wasserburg (1990) for helium and Porcelli and Wasserburg (1995a) for xenon. The model explains the available observational data of mantle helium, neon, argon, and xenon isotope compositions and provides specific predictions regarding the rare gas isotopic compositions

D. Porcelli; G. J. Wasserburg

1995-01-01

140

Preparation of xenon-133 in a lipid emulsion for tissue perfusion studies  

SciTech Connect

A simple, inexpensive technique for concentrating xenon-133 in a medium suitable for intravenous use is reported. The method uses a 20% lipid emulsion, standard syringes, an oscillating motor, and xenon-133, which is available commercially. Typically, 43% of the xenon-133 combines with the lipid emulsion and remains stable for more than 24 hours in vitro.

Hoff, B.; Johnston, G.; Moorman, R.; Matjasko, J.; Sorandes, T.; Hoff, S. (Univ. of Maryland, Baltimore (USA))

1990-06-01

141

The distributed Slow Control System of the XENON100 experiment  

NASA Astrophysics Data System (ADS)

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, was designed to search for evidence of dark matter interactions inside a volume of liquid xenon using a dual-phase time projection chamber. This paper describes the Slow Control System (SCS) of the experiment with emphasis on the distributed architecture as well as on its modular and expandable nature. The system software was designed according to the rules of Object-Oriented Programming and coded in Java, thus promoting code reusability and maximum flexibility during commissioning of the experiment. The SCS has been continuously monitoring the XENON100 detector since mid 2008, remotely recording hundreds of parameters on a few dozen instruments in real time, and setting emergency alarms for the most important variables.

Aprile, E.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Balan, C.; Baudis, L.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, E.; Bruno, G. M.; Budnik, R.; Le Calloch, M.; Cardoso, J. M.; Chen, W.-T.; Choi, B.; Contreras, H.; Cussonneau, J.-P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Gao, F.; Garbini, M.; Giboni, K.-L.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; McKinsey, D. N.; Kish, A.; Lamblin, J.; Lang, R. F.; Levy, C.; Lim, K. E.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Manzur, A.; Marrodn Undagoitia, T.; Massoli, F. V.; Mei, Y.; Melgarejo Fernandez, A. J.; Meng, Y.; Molinario, A.; Nativ, E.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Patricio, J. V.; Persiani, R.; Plante, G.; Priel, N.; Ribeiro, A. C. C.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Scovell, P. R.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

2012-12-01

142

Development of a xenon detector for treaty verification. Final report  

SciTech Connect

The project objective was to determine the feasibility of the gas proportional scintillator detector (GPSD) technology to sensitively and selectively detect the decay products of the metastable xenon isotopes as a means of treaty verification for the CTBT. During the course of the project, the investigation involved both computer simulations and laboratory measurements with a GPSD. During the fourth quarter the authors have further investigated the dedicated GPSD response to x-rays and conversion electrons from {sup 109}Cd and {sup 57}Co radioactive sources, comparing simulated and experimental results. The response of a customized high pressure GPSC was also simulated to the higher energy conversion electrons from xenon radioisotopes. An alternative hybrid detector system is proposed showing excellent prospects for xenon radioisotope detection.

NONE

1998-07-21

143

Study of the electromagnetic background in the XENON100 experiment  

SciTech Connect

The XENON100 experiment, located at the Laboratori Nazionali del Gran Sasso, aims to directly detect dark matter in the form of weakly interacting massive particles via their elastic scattering off xenon nuclei. We present a comprehensive study of the predicted electronic recoil background coming from radioactive decays inside the detector and shield materials and intrinsic radioactivity in the liquid xenon. Based on GEANT4 Monte Carlo simulations using a detailed geometry together with the measured radioactivity of all detector components, we predict an electronic recoil background in the energy region of interest and 30 kg fiducial mass of less than 10{sup -2} events{center_dot}kg{sup -1{center_dot}}day{sup -1{center_dot}}keV{sup -1}, consistent with the experiment's design goal. The predicted background spectrum is in very good agreement with the data taken during the commissioning of the detector in Fall 2009.

Aprile, E.; Choi, B.; Giboni, K.-L.; Lang, R. F.; Lim, K. E.; Melgarejo Fernandez, A. J.; Plante, G. [Physics Department, Columbia University, New York, New York 10027 (United States); Arisaka, K.; Cline, D.; Lam, C. W.; Lung, K.; Pantic, E.; Teymourian, A.; Wang, H. [Physics and Astronomy Department, University of California, Los Angeles (United States); Arneodo, F. [INFN, Laboratori Nazionali del Gran Sasso, Assergi, 67100 (Italy); Askin, A.; Baudis, L.; Behrens, A.; Ferella, A. D.; Kish, A. [Physics Institute, University of Zuerich, Winterthurerstrasse 190, CH-8057, Zuerich (Switzerland)

2011-04-15

144

Modeling the Energy Resolution of Xenon with NEST  

NASA Astrophysics Data System (ADS)

In addition to explaining the mean yields, NEST (the Noble Element Simulation Technique) can also address the energy resolution degrading effects in noble elements, for both electron and nuclear recoils (ER and NR). Liquid and gaseous xenon will be presented as examples. A non-binomial recombination fluctuation model will be discussed which well describes the intrinsic, supra-Poissonian resolution observed in xenon. It is combined with electric field effects, the Fano factor, and detector efforts, such as finite light collection efficiency and PMT quantum efficiency. In matters of conflicting dark matter search results observed by experiments such as XENON100 and CoGeNT, a stochastic, non-analytic, partially non-Gaussian understanding of the energy resolution for low-energy, WIMP-like nuclear recoils may be part of the solution. ER-NR discrimination can be predicted well with such an understanding.

Uvarov, Sergey

2013-04-01

145

TOPICAL REVIEW: Hyperpolarized xenon in NMR and MRI  

NASA Astrophysics Data System (ADS)

Hyperpolarized gases have found a steadily increasing range of applications in nuclear magnetic resonance (NMR) and NMR imaging (MRI). They can be regarded as a new class of MR contrast agent or as a way of greatly enhancing the temporal resolution of the measurement of processes relevant to areas as diverse as materials science and biomedicine. We concentrate on the properties and applications of hyperpolarized xenon. This review discusses the physics of producing hyperpolarization, the NMR-relevant properties of 129Xe, specific MRI methods for hyperpolarized gases, applications of xenon to biology and medicine, polarization transfer to other nuclear species and low-field imaging.

Oros, Ana-Maria; Shah, N. Jon

2004-10-01

146

Xenon purity analysis for EXO-200 via mass spectrometry  

NASA Astrophysics Data System (ADS)

We describe purity measurements of the natural and enriched xenon stockpiles used by the EXO-200 double beta decay experiment based on a mass spectrometry technique. The sensitivity of the spectrometer is enhanced by several orders of magnitude by the presence of a liquid nitrogen cold trap, and many impurity species of interest can be detected at the level of one part-per-billion or better. We have used the technique to screen the EXO-200 xenon before, during, and after its use in our detector, and these measurements have proven useful. This is the first application of the cold trap mass spectrometry technique to an operating physics experiment.

Dobi, A.; Hall, C.; Slutsky, S.; Yen, Y.-R.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Benitez-Medina, C.; Breidenbach, M.; Cleveland, B.; Conley, R.; Cook, J.; Cook, S.; Counts, I.; Craddock, W.; Daniels, T.; Davis, C. G.; Davis, J.; deVoe, R.; Dixit, M.; Dolinski, M. J.; Donato, K.; Fairbank, W.; Farine, J.; Fierlinger, P.; Franco, D.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Green, C.; Hagemann, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Hughes, M.; Hodgson, J.; Juget, F.; Karelin, A.; Kaufman, L. J.; Kuchenkov, A.; Kumar, K.; Leonard, D. S.; Lutter, G.; Mackay, D.; MacLellan, R.; Marino, M.; Mong, B.; Montero Dez, M.; Morgan, P.; Mller, A. R.; Neilson, R.; Odian, A.; O'Sullivan, K.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rivas, A.; Rollin, E.; Rowson, P. C.; Sabourov, A.; Sinclair, D.; Skarpaas, K.; Stekhanov, V.; Strickland, V.; Swift, M.; Twelker, K.; Vuilleumier, J.-L.; Vuilleumier, J.-M.; Weber, M.; Wichoski, U.; Wodin, J.; Wright, J. D.; Yang, L.

2012-05-01

147

Properties of liquid xenon scintillation for dark matter searches  

NASA Astrophysics Data System (ADS)

The scintillation yields and decay shapes for recoil Xe ions produced by WIMPs in liquid xenon have been examined. A quenching model based on a biexcitonic diffusion-reaction mechanism is proposed for electronic quenching. The total predicted quenching, nuclear and electronic, is compared with experimental results reported for nuclear recoils from neutrons. Model calculations give the average energy to produce a vuv photon, Wph, to be 75 eV for 60 keV recoil Xe ions. Some aspects of ionization relating to liquid xenon WIMP detectors are also discussed.

Hitachi, Akira

2005-10-01

148

Low Mass WIMP Search Using High Pressure Xenon Gas  

NASA Astrophysics Data System (ADS)

Several groups around the globe employ unique detector technologies in the direct search for dark matter weakly interacting massive particles (WIMPs). One of the leading technologies uses scintillation and ionization signals produced when WIMPs scatter off xenon nuclei. Recent compelling results hint at the possibility of a less massive WIMP (7 -- 10 GeV/c^2), than was previously thought. A plan will be presented for a low mass WIMP search using high pressure xenon, and possibly neon gas. The design, calibration, and expected results will be discussed.

Sofka, Clement

2012-10-01

149

A Study of Radon Background in the XENON100 Experiment  

NASA Astrophysics Data System (ADS)

The XENON100 Dark Matter experiment has recently published first results from an analysis of 11.2 live days of data, setting an upper limit on the spin-independent WIMP-nucleon elastic scattering cross section of 3.410-44 cm2 at 55 GeV/c2 and 90% confidence level. This article focuses on one specific background component of the XENON100 detector by presenting two independent methods of measuring the 222Rn concentration during operation phase. A first estimate of radon activity is derived for the 11.2 days analysis, proving the feasibility of on-line radon monitoring. Remaining systematic uncertainties are discussed.

Weber, Marc

2011-04-01

150

Properties of excited xenon atoms in an alternating current plasma display panel  

NASA Astrophysics Data System (ADS)

The properties of excited xenon atoms in the discharge cells of a plasma display panel are investigated by measuring the excited atom density via laser absorption spectroscopy. The density of the excited xenon atoms in the metastable state increases from zero, reaches its peak, and decreases with time in the discharge cells, as expected from a theoretical model. The profile of an excited xenon atom is also studied in terms of the xenon mole fraction. The typical density of excited xenon atoms in a metastable state is on the order of 1013 atoms/cm3.

Uhm, Han S.; Oh, Phil Y.; Choi, Eun H.

2008-11-01

151

[Electroencephalogram, informational saturation of electroencephalogram, and bispectral index during xenon anesthesia for laparoscopic operations].  

PubMed

The depth of xenon anesthesia was never evaluated by modern methods of EEG monitoring, and hence, we studied changes in EEG, INEEG, and BIS during different stages of xenon narcosis and evaluated the possibility of using these values as criteria of xenon anesthesia adequacy. The study was carried out in 60 patients during laparoscopic operations on abdominal organs. The patients were divided into 2 groups receiving different gas anesthetics (xenon or nitric oxide). The results indicate that xenon monoanesthesia caused dose-dependent changes in the native and treated EEG; xenon is a good inhalation anesthetic providing adequate anesthesia for little traumatic operations even in case of mononarcosis; INEEG and BIS monitoring during xenon anesthesia allows an objective evaluation of its depth. PMID:12221874

Likhvantsev, V V; Volovik, A G; Petrov, O V; Sitnikov, A V; Subbotin, V V

152

ADVANCED TEST REACTOR. AXIAL XENON STABILITY. Study SR122  

Microsoft Academic Search

Stability of the Advanced Test Reactor (ATR) with axial xenon ; oscillations has been calculated using one-dimension analytic methods, digital-; computer codes, and analog computer simulations. It is concluded from these ; studies that the reference length is stable, but may exhibit an underdamped ; response to axial flux perturbations. The geometry problems that complicate all ; ATR nuclear calculations

Spetz

1962-01-01

153

Small Water-Cooled Non-Ballast Tubular Xenon Lamp.  

National Technical Information Service (NTIS)

The work gives a description of a small non-ballast water-cooled tubular xenon lamp operating on alternating current with an input voltage of 220 v. The parameters of the optimal operation of the lamp are discussed and the electrical and luminous characte...

I. L. Tokhadze V. I. Vasilev I. S. Marshak

1968-01-01

154

CORTICOSTEROID-INDUCED VASOCONSTRICTION STUDIED BY XENON 133 CLEARANCE  

Microsoft Academic Search

Cutaneous blood flow in corticosteroid-blanched skin was measured by xenon 133 clearance. Flow rates through symmetrical sites of the forearm in normal subjects revealed no significant differences. A comparison of control sites and those treated with flurandrenolide revealed a significant vasoconstriction at the test site. The results suggest that vasoconstriction activity of topical corticosteroids may be quantitated utilizing isotope clearance

Terrence P. Greeson; Norman E. Levan; Robert I. Freedman; Woon H. Wong

1973-01-01

155

Subsurface nuclear tests monitoring through the CTBT xenon network  

Microsoft Academic Search

We present the first evaluation of the atmospheric xenon network to be installed as part of the International Monitoring System (IMS) in the frame of the Comprehensive Test Ban Treaty (CTBT). We show that this network should, by itself, provide a significant contribution to the total efficiency of the IMS. For this evaluation, we introduce an inverse approach based upon

Frdric Hourdin; J.-P. Issartel

2000-01-01

156

Liquids xenon and argon, dark matter detectors with background rejection  

Microsoft Academic Search

The potential of liquids xenon and argon as dark matter targets is discussed emphasising the former. Significant discrimination of very small signals against beta\\/gamma backgrounds can be achieved in several ways; firstly via the collection of scintillation light alone in conjunction with a likelihood technique to fully exploit the digitised photon arrival times; secondly via the collection of both light

G. J. Davies

1997-01-01

157

Xe-129 NMR of xenon dissolved in biological media.  

NASA Astrophysics Data System (ADS)

The high solubility and large chemical shift of ^129Xe in various tissues makes it an ideal, non-invasive probe for pathological conditions such as cancer or atherosclerosis. To this end, we report NMR measurements of lineshapes, chemical shifts, and relaxation times of ^129Xe dissolved in the following biological tissues in vitro: heart, muscle, sinew, stomach(R.K. Mazitov, K. M. Enikeev, et al., Dokl. Akad. Nauk) 365, 396 (1999)., and the white and yolk of egg. NMR measurements of xenon dissolved in olive and sunflower oils are also reported. Tissues weighing 160--250 mg, not exposed to freezing, were studied in a 11.75 T field at the ^129Xe resonance frequency of 138.4 MHz; the pressure of xenon in the sealed-sample ampoules was ~20 bar. The influence of drugs and water content on tissues was studied. No xenon-water clathrates(J.A. Ripmeester and D.W. Davidson, J. Mol. Struct. ) 75, 67 (1981). were observed in the tissues, even at the high pressures used. The aim of this study is to establish possible correlations between the NMR parameters of dissolved xenon and the state of the tissue.

Mazitov, R. K.; Kuzma, N. N.; Happer, W.; Driehuys, B.; Merrill, G. F.

2002-03-01

158

Ultraviolet Absorption of Solid Argon, Krypton, and Xenon  

Microsoft Academic Search

The absorption spectra of thin films of argon, krypton, and xenon have been measured between 20 and 50K in the region from 1600 to 900 (8 to 14 eV). The spectra show: (a) strong doublets corresponding to the atomic resonance doublets, (b) lines apparently of nonatomic nature, and (c) absorption continua. The experimental results are discussed in terms of

Giancarlo Baldini

1962-01-01

159

Thermophysical properties of neon, argon, krypton, and xenon  

Microsoft Academic Search

Addressing the thermophysical properties of the rare gas elements - neon, argon, krypton, and xenon - this thorough work offers new research and uniform data. Tables cover properties in these elements crystalline, liquid, and gaseous states, spanning a temperature range of 0-1300 K, and for pressures up to 100 MPa. This volume contains thermodynamic properties in the solid phase and

V. A. Rabinovich; A. A. Vasserman; V. I. Nedostup; L. S. Veksler

1987-01-01

160

Density Functional Theory (dft) Simulations of Shocked Liquid Xenon  

NASA Astrophysics Data System (ADS)

Xenon is not only a technologically important element used in laser technologies and jet propulsion, but it is also one of the most accessible materials in which to study the metal-insulator transition with increasing pressure. Because of its closed shell electronic configuration, xenon is often assumed to be chemically inert, interacting almost entirely through the van der Waals interaction, and at liquid density, is typically modeled well using Leonard-Jones potentials. However, such modeling has a limited range of validity as xenon is known to form compounds under normal conditions and likely exhibits considerably more chemistry at higher densities when hybridization of occupied orbitals becomes significant. We present DFT-MD simulations of shocked liquid xenon with the goal of developing an improved equation of state. The calculated Hugoniot to 2 MPa compares well with available experimental shock data. Sandia is a mul-tiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Mattsson, Thomas R.; Magyar, Rudolph J.

2009-12-01

161

Density Functional Theory (DFT) Simulations of Shocked Liquid Xenon  

NASA Astrophysics Data System (ADS)

Xenon is not only a technologically important element used in laser technologies and jet propulsion, but it is also one of the most accessible materials in which to study the metal-insulator transition with increasing pressure. Because of its closed shell electronic configuration, Xenon is often assumed to be chemically inert, interacting almost entirely through the van der Waals interaction, and at liquid density, is typically modeled well using Leonard-Jones potentials. However, such modeling has a limited range of validity as Xenon is known to form compounds at normal conditions and likely exhibits considerably more chemistry at higher densities when hybridization of occupied orbitals becomes significant. In this talk, we present DFT-MD simulations of shocked liquid Xenon with the goal of developing an improved equation of state. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Mattsson, Thomas R.; Magyar, Rudolph J.

2009-06-01

162

Liquid xenon scintillation calorimetry and Xe optical properties  

Microsoft Academic Search

The optical properties of liquid xenon (LXe) in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be

A. Baldini; C. Bemporad; F. Cei; T. Doke; M. Grassi; T. Haruyama; S. Mihara; T. Mori; D. Nicolo; H. Nishiguchi; W. Ootani; K. Ozone; A. Papa; R. Pazzi; R. Sawada; F. Sergiampietri; G. Signorelli; S. Suzuki; K. Terasawa

2006-01-01

163

Properties of Liquid Xenon Scintillation for WIMP Searches  

Microsoft Academic Search

The scintillation yields and decay shapes for recoil Xe-ions produced by WIMPs in liquid xenon have been considered. A rough calculation based on biexcitonic diffusion reaction mechanism gives the average energy to produce a vuv photon Wph to be ~90 eV for 60 keV recoil Xe-ions.

Akira Hitachi

2003-01-01

164

Properties of Liquid Xenon Scintillation for WIMP Searches  

NASA Astrophysics Data System (ADS)

The scintillation yields and decay shapes for recoil Xe-ions produced by WIMPs in liquid xenon have been considered. A rough calculation based on biexcitonic diffusion reaction mechanism gives the average energy to produce a vuv photon Wph to be ~90 eV for 60 keV recoil Xe-ions.

Hitachi, Akira

2003-03-01

165

Density dependence of the depolarized light scattering spectrum of xenon  

Microsoft Academic Search

Measurements of the depolarized light scattering spectra of xenon at densities between 0.2 and 2.6 times the critical density are presented. The density dependences of the first three even spectral moments are compared with the predictions by the theory under several simplifying assumptions where use is made of data for the static structure factor from the literature. Comparison is also

J. van der Elsken; R. A. Huijts

1988-01-01

166

Shock Waves in Xenon Flashtubes and Tube Deterioration  

Microsoft Academic Search

The xenon-filled arc discharge tube has found wide applications as an optical pumping source for ruby lasers. An experimental study of the shock waves in the flashtube at laser pumping energies and their effect on tube deterioration has been made. The plasma discharge was investigated by taking high-speed image converter and streak photographs of the discharge and by measuring the

Kenneth R. Lang; Frank S. Barnes

1964-01-01

167

Application of xenon difluoride for surface modification of polymers.  

National Technical Information Service (NTIS)

Chemical interaction between xenon difluoride (XeF(sub 2)) and polymeric materials was investigated. It was shown that the reaction occurs on the surface of solid polymer layer and brings to chemical modification of the surface properties of the polymer l...

G. B. Barsamyan K. V. Belokonov N. A. Vargasova V. B. Sokolov B. B. Chaivanov

1994-01-01

168

Introducing Hyperpolarized Xenon-131 Directly Detected by NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

Previously, high-field NMR and MRI applications of hyperpolarized (hp) noble gasses focused on the isotopes helium-3 (spin I = 1/2), xenon-129 (spin I = 1/2) [1], and more recently krypton-83 (spin I = 9/2) [2]. In this contribution, hp xenon-131 (spin I = 3/2) was generated by spin-exchange optical pumping and separated from the rubidium vapor for high field NMR detection at 14.1 T field strength. Xenon-131 is of particular interest because of its quadrupolar nature that can be utilized for the study of surfaces [3] and for the investigation of high magnetic field effects on the electronic structure of the noble gas atom [4]. In addition, this isotope is a useful probe for quadrupolar processes during gas transfer and during NMR/MRI detection. Experiments with xenon-131, including multiple quantum filtered NMR spectroscopy [3], provides insights into similar processes present in krypton-83 and its more complicated spin system [5]. [1] D. Raftery Ann. Rep. NMR Spec., 57, 208 (2006). [2] G. Pavlovskaya, et al., Pro. Natl. Acad. Sci. U.S.A. 102, 18275 (2005). [3] T. Meersmann et al., Phys. Rev. Lett. 80, 1398 (1998). [4] T. Meersmann and M. Haake, Phys. Rev. Lett. 81, 1211 (1998). [5] Z. Cleveland, et al., J. Chem. Phys.124, 044312 (2006).

Stupic, Karl; Cleveland, Zackary; Pavlovskaya, Galina; Meersmann, Thomas

2007-03-01

169

Properties of liquid xenon scintillation for dark matter searches  

Microsoft Academic Search

The scintillation yields and decay shapes for recoil Xe ions produced by WIMPs in liquid xenon have been examined. A quenching model based on a biexcitonic diffusion-reaction mechanism is proposed for electronic quenching. The total predicted quenching, nuclear and electronic, is compared with experimental results reported for nuclear recoils from neutrons. Model calculations give the average energy to produce a

Akira Hitachi

2005-01-01

170

Photoionization detector for the detection of xenon light  

SciTech Connect

A photionization detector is described with a high quantum efficiency at wavelengths shorter than about 2000 A. This instrument, coupled to a xenon gas scintillation proportional counter has an energy resolution of 9.5% FWHM at 6 keV. The vapor pressure and absorption coefficient of TMAE are measured and the prospects of an imaging gas scintillation proportional counter are discussed.

Anderson, D.F.

1980-01-01

171

Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes  

NASA Astrophysics Data System (ADS)

Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Kathawa, J.; Fry, C.; Thoennessen, M.

2013-01-01

172

Sound Absorption and Dispersion along the Critical Isochore in Xenon  

Microsoft Academic Search

Ultrasonic and Brillouin absorption and velocity data along the critical isochore in xenon are reinterpreted in terms of modified theoretical expressions derived within the framework of the Fixman-Mistura theory. The new expressions mainly arise from avoiding the unjustified assumption of small dispersion near a liquid-gas critical point. Numerical analysis of the data shows quite satisfactory agreement between theory and experiment

Don Eden; Carl W. Garland; Jan Thoen

1972-01-01

173

Townsend First Coefficient in Argon, Xenon and Their Mixture.  

National Technical Information Service (NTIS)

The ionization coefficient of alpha /P as a function of E/P is determined for argon, xenon and the Ar+0.5% Xe mixture at pressure up to 100 atm. ( alpha - Townsend coefficient, P - gas pressure, E - electric field strength). The findings differ essentiall...

V. K. Dodoknov V. A. Zhukov

1980-01-01

174

Molecule Shapes  

NSDL National Science Digital Library

Explore molecule shapes by building molecules in 3D! How does molecule shape change with different numbers of bonds and electron pairs? Find out by adding single, double or triple bonds and lone pairs to the central atom. Then, compare the model to real molecules!

Simulations, Phet I.; Moore, Emily; Olson, Jonathan; Lancaster, Kelly; Chamberlain, Julia; Perkins, Kathy

2011-10-10

175

Carbon dioxide enhances fragility of ice crystals  

NASA Astrophysics Data System (ADS)

Ice caps and glaciers cover 7% of the Earth, greater than the land area of Europe and North America combined, and play an important role in global climate. The small-scale failure mechanisms of ice fracture, however, remain largely elusive. In particular, little understanding exists about how the presence and concentration of carbon dioxide molecules, a significant component in the atmosphere, affects the propensity of ice to fracture. Here we use atomic simulations with the first-principles based ReaxFF force field capable of describing the details of chemical reactions at the tip of a crack, applied to investigate the effects of the presence of carbon dioxide molecules on ice fracture. Our result shows that increasing concentrations of carbon dioxide molecules significantly decrease the fracture toughness of the ice crystal, making it more fragile. Using enhanced molecular sampling with metadynamics we reconstruct the free energy landscape in varied chemical microenvironments and find that carbon dioxide molecules affect the bonds between water molecules at the crack tip and decrease their strength by altering the dissociation energy of hydrogen bonds. In the context of glacier dynamics our findings may provide a novel viewpoint that could aid in understanding the breakdown and melting of glaciers, suggesting that the chemical composition of the atmosphere can be critical to mediate the large-scale motion of large volumes of ice.

Qin, Zhao; Buehler, Markus J.

2012-11-01

176

Mesoscale Backtracking by Means of Atmospheric Transport Modeling of Xenon Plumes Measured by Radionuclide Gas Stations  

NASA Astrophysics Data System (ADS)

The monitoring of atmospheric radioactive xenon concentration is performed for nuclear safety regulatory requirements. It is also planned to be used for the detection of hypothetical nuclear tests in the framework of the Comprehensive nuclear-Test-Ban Treaty (CTBT). In this context, the French Atomic Energy Commission designed a high sensitive and automated fieldable station, named SPALAX, to measure the activity concentrations of xenon isotopes in the atmosphere. SPALAX stations were set up in Western Europe and have been operated quite continuously for three years or more, detecting principally xenon-133 and more scarcely xenon-135, xenon-133m and xenon-131m. There are around 150 nuclear power plants in the European Union, research reactors, reprocessing plants, medical production and application facilities releasing radioactive xenon in normal or incidental operations. A numerical study was carried out aiming to explain the SPALAX measurements. The mesoscale Atmospheric Transport Modelling involves the MM5 suite (PSU- NCAR) to predict the wind fields on nested domains, and FLEXPART, a 3D Lagrangian particle dispersion code, used to simulate the backward transport of xenon plumes detected by the SPALAX. For every event of detection, at least one potential xenon source has a significant efficiency of emission. The identified likely sources are located quite close to the SPALAX stations (some tens of kilometres), or situated farther (a few hundreds of kilometres). A base line of some mBq per cubic meter in xenon-133 is generated by the nuclear power plants. Peaks of xenon-133 ranging from tens to hundreds of mBq per cubic meter originate from a radioisotope production facility. The calculated xenon source terms required to obtain the SPALAX measurements are discussed and seem consistent with realistic emissions from the xenon sources in Western Europe.

Armand, P. P.; Achim, P.; Taffary, T.

2006-12-01

177

SORPTION BEHAVIOUR AND SWELLING OF POLYMERS IN A CARBON DIOXIDE ATMOSPHERE AT TRANSCRITICAL CONDITIONS  

Microsoft Academic Search

Considering the sealing of moving and unmoving components and assemblies in refrigerating plants using carbon dioxide as a refrigerant it is important to know that small carbon dioxide molecules can diffuse into polymers. The carbon dioxide accumulates in the polymer which leads to swelling. Additionally, the seals strained at supercritical pressure can be destroyed by an explosive decompression. The sorption

R. Eggers

178

Molecule nanoweaver  

DOEpatents

A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

Gerald, II; Rex E. (Brookfield, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Homer Glen, IL); Diaz, Rocio (Chicago, IL); Vukovic, Lela (Westchester, IL)

2009-03-10

179

Segregation of xenon to dislocations and grain boundaries in uranium dioxide  

SciTech Connect

It is well known that Xe, being insoluble in UO{sub 2}, segregates to dislocations and grain boundaries (GBs), where bubbles may form resulting in fuel swelling. Less well known is how sensitive this segregation is to the structure of the dislocation or GB. In this work we employ pair potential calculations to examine Xe segregation to dislocations (edge and screw) and several representative grain boundaries ({Sigma}5 tilt, {Sigma}5 twist, and random). Our calculations predict that the segregation trend depends significantly on the type of dislocation or GB. In particular we find that Xe prefers to segregate strongly to the random boundary as compared to the other two boundaries and to the screw dislocation rather than the edge. Furthermore, we observe that neither the volumetric strain nor the electrostatic potential of a site can be used to predict its segregation characteristics. These differences in segregation characteristics are expected to have important consequences for the retention and release of Xe in nuclear fuels. Finally, our results offer general insights into how atomic structure of extended defects influence species segregation.

Nerikar, P. V.; Casillas Trujillo, L. A.; Andersson, D. A.; Unal, C.; Uberuaga, B. P.; Stanek, C. R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Parfitt, D. C.; Grimes, R. W. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Sinnott, S. B. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)

2011-11-01

180

Segregation of xenon to dislocations and grain boundaries in uranium dioxide  

NASA Astrophysics Data System (ADS)

It is well known that Xe, being insoluble in UO2, segregates to dislocations and grain boundaries (GBs), where bubbles may form resulting in fuel swelling. Less well known is how sensitive this segregation is to the structure of the dislocation or GB. In this work we employ pair potential calculations to examine Xe segregation to dislocations (edge and screw) and several representative grain boundaries (?5 tilt, ?5 twist, and random). Our calculations predict that the segregation trend depends significantly on the type of dislocation or GB. In particular we find that Xe prefers to segregate strongly to the random boundary as compared to the other two boundaries and to the screw dislocation rather than the edge. Furthermore, we observe that neither the volumetric strain nor the electrostatic potential of a site can be used to predict its segregation characteristics. These differences in segregation characteristics are expected to have important consequences for the retention and release of Xe in nuclear fuels. Finally, our results offer general insights into how atomic structure of extended defects influence species segregation.

Nerikar, P. V.; Parfitt, D. C.; Casillas Trujillo, L. A.; Andersson, D. A.; Unal, C.; Sinnott, S. B.; Grimes, R. W.; Uberuaga, B. P.; Stanek, C. R.

2011-11-01

181

Spectroscopic evidence of reversible micro-crystallization of carbon dioxide dissolved in solid xenon  

NASA Astrophysics Data System (ADS)

FTIR spectra of CO2 dissolved in liquid and solid Xe have been studied in 1000 6000 cm?1 frequency domain at T 170 100 K. Apart a set of the fundamental and combination bands of the solute CO2, a set of new bands ascribed to crystalline CO2 have been found in the solid species. The crystallization process is reversible with respect to temperature variations. The qualitative change of the intensity ratio between the low-and high frequency components of the Fermi resonance ?u doublet (1110)I/(1110)II has been revealed for the crystalline CO2.

Rutkowski, K. S.; Melikova, S. M.; Herrebout, W. A.; van der Veken, B. J.

2013-09-01

182

A portable gamma-ray spectrometer using compressed xenon  

SciTech Connect

An ionization chamber using compressed xenon has been designed and built for gamma-ray spectrometry. The device is based on signal measurement from a parallel plate detector, with the gas enclosure constructed specifically for packaging into a portable instrument; thus, appropriate engineering practices comprises two small containers that can be setup for operation in just a few minutes. Its sensitivity is 100 keV to over 1 MeV, with a resolution at 662 keV of 2.5% FWHM for uniform irradiation, and 2% FWHM for collimated irradiation, comparable to the best ever with compressed xenon. It also exhibits greater specificity that most scintillators, such as NaI. The device is insensitive to neutron damage and has a low power requirement.

Mahler, G.J.; Yu, B.; Smith, G.C.; Kane, W.R.; Lemley, J.R.

1997-10-01

183

The uses of helium and xenon in current clinical practice.  

PubMed

The noble gases have always been an enigma. Discovered late in the history of chemistry and in seemingly small quantities in our atmosphere, they are some of the most unreactive elements known. However, despite being extremely inert, the noble gases (helium, neon, argon, krypton, xenon and radon) have found diverse and ever expanding applications in medicine. Of all of them, the gases that have found the greatest number of uses in the field of anaesthesia and related specialties are helium and xenon. This review focuses on the history of the discovery of both gases, their unique physicochemical properties and describes their uses in clinical practice with particular emphasis on those applicable to anaesthesia. PMID:18289236

Harris, P D; Barnes, R

2008-03-01

184

Xenon NMR measurements of permeability and tortuosity in reservoir rocks.  

PubMed

In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores. PMID:15833638

Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

2005-02-01

185

RELAX-1, A Refrigerator Enhanced Laser Analyzer for Xenon  

NASA Astrophysics Data System (ADS)

A time-of-flight mass spectrometer with a resonance ionization source [1,2] and a cryogenic sample concentrator [3,4] which increases the efficiency of the spectrometer by two orders of magnitude, has been constructed for the isotopic analysis of xenon. In the two-photon excitation, one-photon ionization scheme employed, a wavelength of 249.6 nm excites the 2P(sub)3/26p[1/2](sub)0 level of xenon. A pulsed laser operating at 10 Hz, with a pulse duration of 8 ns and energy of 1.5 mJ is used. The sample concentrator consists of a localised cold spot (<90 K) onto which the xenon sample is condensed. The spot is heated by a Nd:YAG laser (25 mJ, 6 ns), evaporating the condensed sample gas into the ionizing region 1 us (chosen for optimum sensitivity) before the ionizing laser is fired. The mean return time to the cold spot is about 10 seconds in the 450-ml spectrometer and corresponds to an effective spot diameter of 1 mm. With each laser shot, 1% of the atoms released by the heating laser are ionized and, between shots, 1% of the sample recondenses onto the cold spot. Thus at 10 Hz, 1000 atoms produce a signal of 1 cps, which compares with a typical sensitivity of around 15,000 atoms/cps for conventional instruments. Since all isotopes are detected simultaneously, the effective sensitivity is more than two orders of magnitude greater than a single collector conventional instrument. Furthermore the background count rate due to multiplier dark current at a given mass is negligible (1 count per week) and the sole limitation on ultimate sample size is adsorbed xenon on the sample and the spectrometer walls. The velocity distribution of atoms leaving the cold finger has been determined by varying the delay between heating and ionizing lasers, and is Maxwellian with an angular dependence of the form cos^n(q) (n>5) and a characteristic temperature of 350 K. For sampled atoms of velocity v and characteristic temperature T, the theoretical instrumental discrimination [3] is 3/2m-1.66 x 10^27 v^2/2kT per mil per amu and is confirmed by experiment. Nonresonant ionization of hydrocarbons may occur at the high power densities necessary to saturate the two-photon transition of xenon (about 10^-9 Wcm^-2). Residual hydrocarbon effects in the spectrometer are monitored by detuning the wavelength of the ionizing laser away from resonance and are negligible. One side effect of the sample concentrator is that hydrocarbons tend to condense on parts of the cold spot the heating laser does not reach. Moreover most of the hydrocarbons that are evaporated leave the surface with velocities different from those of xenon and do not see the ionising laser beam. The spectrometer is currently being used to analyse xenon in meteorite residues and cosmogenic xenon in terrestrial barite. References 1. C H Chen, G S Hurst, M G Payne (1980) Chem. Phys. Lett. 75, 473-477. 2. J D Gilmour, S M Hewett, I C Lyon, M Stringer, G Turner (1991) Meas. Sci. Technol. 2, 589-595. 3. J D Gilmour, S M Hewett, I C Lyon, I Perera, G Turner, in prep. 4. G S Hurst, M G Payne, R C Phillips, J W T Dabbs, B E Lehmann (1984) J. Appl. Phys. 55, 1278-1284.

Gilmour, J. D.; Johnston, W. A.; Lyon, I. C.; Turner, G.

1992-07-01

186

A Study of Radon Background in the XENON100 Experiment  

SciTech Connect

The XENON100 Dark Matter experiment has recently published first results from an analysis of 11.2 live days of data, setting an upper limit on the spin-independent WIMP-nucleon elastic scattering cross section of 3.4x10{sup -44} cm{sup 2} at 55 GeV/c{sup 2} and 90% confidence level. This article focuses on one specific background component of the XENON100 detector by presenting two independent methods of measuring the {sup 222}Rn concentration during operation phase. A first estimate of radon activity is derived for the 11.2 days analysis, proving the feasibility of on-line radon monitoring. Remaining systematic uncertainties are discussed.

Weber, Marc [Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany)

2011-04-27

187

Constraints on inelastic dark matter from XENON10  

SciTech Connect

It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to E{sub nr} = 75 keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses m{sub x} {approx}> 150 GeV are disfavored.

Angle, J; Aprile, E; Arneodo, F; Baudis, L; Bernstein, A; Bolozdynya, A; Coelho, L C; Dahl, C E; DeViveiros, L; Ferella, A D; Fernandes, L P; Fiorucci, S; Gaitskell, R J; Giboni, K L; Gomez, R; Hasty, R; Kastens, L; Kwong, J; Lopes, J M; Madden, N; Manalaysay, A; Manzur, A; McKinsey, D N; Monzani, M E; Ni, K; Oberlack, U; Orboeck, J; Plante, G; Santorelli, R; dos Santos, J; Shagin, P; Shutt, T; Sorensen, P; Schulte, S; Winant, C; Yamashita, M

2009-11-23

188

First Dark Matter Results from the XENON100 Experiment  

SciTech Connect

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3.4x10{sup -44} cm{sup 2} for 55 GeV/c{sup 2} WIMPs at 90% confidence level. Below 20 GeV/c{sup 2}, this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Aprile, E.; Choi, B.; Giboni, K.-L.; Lang, R. F.; Lim, K. E.; Melgarejo Fernandez, A. J.; Plante, G. [Physics Department, Columbia University, New York, New York 10027 (United States); Arisaka, K.; Brown, E.; Cline, D. B.; Lam, C. W.; Pantic, E.; Teymourian, A.; Wang, H. [Physics and Astronomy Department, University of California, Los Angeles (United States); Arneodo, F.; Fattori, S. [INFN Laboratori Nazionali del Gran Sasso, Assergi, 67100 (Italy); Askin, A.; Baudis, L.; Behrens, A.; Ferella, A. D. [Physics Institute, University of Zuerich, Winterthurerstr. 190, CH-8057 (Switzerland)

2010-09-24

189

E- to H-mode Transition in Inductively Coupled Xenon Discharge Lamp  

Microsoft Academic Search

In this paper the phenomena of mode transition and hysteresis in xenon ICP (Inductively Coupled Plasma) discharge are studied. Xenon has been used as an alternative for mercury since there are environmental issues related to mercury. The transition from E-mode (electrostatic mode) discharge to H-mode (electromagnetic mode) discharge in a xenon cylindrical tube was investigated. RF energy at 13.56 MHz

Ahmad Nazri; Shuji Inui; Hideki Motomura; Masafumi Jinno; Masaharu Aono

2005-01-01

190

Xenon inhibits excitatory but not inhibitory transmission in rat spinal cord dorsal horn neurons  

Microsoft Academic Search

BACKGROUND: The molecular targets for the promising gaseous anaesthetic xenon are still under investigation. Most studies identify N-methyl-D-aspartate (NMDA) receptors as the primary molecular target for xenon, but the role of ?-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid (AMPA) receptors is less clear. In this study we evaluated the effect of xenon on excitatory and inhibitory synaptic transmission in the superficial dorsal horn of the

Stefan K Georgiev; Hidemasa Furue; Hiroshi Baba; Tatsuro Kohno

2010-01-01

191

[Spectral characteristic of short-arc xenon lamp and application in solar simulators].  

PubMed

Due to the inhomogeneous spatial spectral distribution of short-arc xenon lamp, its application is difficult. In the present paper, axially spectral distribution of xenon lamp was measured and temperature distribution was calculated, the temperature distribution was analysed as exponential relationship with arc current density. Therefore, xenon lamp spectral distribution can be made closer to the standard solar simulator spectral distribution by controlling current density. PMID:22870616

Li, Qian; Wang, Cheng; Zha, Jun; Xia, Wei-Dong

2012-06-01

192

Viscoelastiticy and shear thinning near the critical point of xenon  

NASA Astrophysics Data System (ADS)

The critical point is the exact combination of pressure and temperature at which a fluid is balanced between the states of liquid and gas. Everyday experience gives no hint of the unusual nature of the critical point because familiar fluids such as air and water are far from their critical temperatures. Understanding the critical point is essential for an understanding of fluids in general because the near-critical behavior is universal. Properly scaled, fluids as dissimilar as air and water have near-critical thermodynamic properties (e.g. heat capacity) and transport properties (e.g. viscosity) that are similar. Sufficiently close to the critical point, theory predicts the similarities to be exact. This talk will describe two measurements of the viscosity of xenon that were made very close (<1 mK) to xenon's critical point (289 K, 5.8 MPa). The first experiment measured the viscosity increase caused by near-critical conditions. It revealed that, close to the critical point, xenon is partly elastic: It can stretch as well as flow. The second experiment, planned for July 2002, will look for the shear-rate-induced viscosity decrease predicted by theory. Such "viscoelasticity" and "shear-thinning" are ordinarily seen only in much more complicated fluids such as polymer solutions. Slowly relaxing fluctuations cause both phenomena. The first experiment found that the time scale for viscoelasticity was 2.0 times slower than predicted. Preliminary results for shear thinning from the second experiment will be reported. Both experiments were designed to operate in the microgravity provided by the Space Shuttle. We required microgravity because Earth's gravity compresses any fluid near its critical point. Near its critical point, a layer of xenon as thin as 1 mm collapses under its own weight until the density at the bottom is 8% greater than at the top. The density difference distorts the data. Conducting the experiments on the Space Shuttle reduces the density difference by a factor of 100.

Berg, R.; Yao, M.; Moldover, M.; Zimmerli, G.

193

Xenon and hypothermia combine to provide neuroprotection from neonatal asphyxia  

Microsoft Academic Search

Perinatal asphyxia can result in neuronal injury with long-term neurological and behavioral consequences. Although hypothermia may provide some modest benefit, the intervention itself can produce adverse consequences. We have investigated whether xenon, an antagonist of the N-methyl-D-aspartate subtype of the glutamate receptor, can enhance the neuroprotection provided by mild hypothermia. Cultured neurons injured by oxygen-glucose deprivation were pro- tected by

Daqing Ma; Mahmuda Hossain; Andre Chow; Mubarik Arshad; Renee M. Battson; Robert D. Sanders; Huseyin Mehmet; A. David Edwards; Nicholas P. Franks; Mervyn Maze

2005-01-01

194

Production of Krypton and Xenon Isotopes by Galactic Protons  

Microsoft Academic Search

The production of krypton from target elements Rb (Rb(sub)2SO(sub)4), Sr (SrF(sub)2), Y, Zr, and of xenon in Ba (Ba glass), La (LaF(sub)3) is studied in a simulation experiment of the galactic cosmic-ray proton bombardment of stony meteoroids in space [1,2]. This investigation is part of the experiment LNS 172 by which a 50-cm-diameter artificial meteoroid (gabbro) was isotropically irradiated at

E. Gilabert; B. Lavielle; G. N. Simonoff; R. Rosel; U. Herpers; M. Schnatz-Buttgen; M. Lupke; R. Michel

1993-01-01

195

Depth distribution of martensite in xenon-implanted stainless steels  

Microsoft Academic Search

The amount of stress-induced martensite and its distribution in depth in xenon-implanted austenitic stainless-steel poly- and single crystals have been measured by Rutherford backscattering and channeling analysis, depth-selective conversion-electron Mssbauer spectroscopy, cross-sectional transmission electron microscopy and X-ray diffraction analysis. In low-nickel 17\\/7, 304 and 316 commercial stainless steels and in 17:13 single crystals the martensitic transformation starts at the surface

A. Johansen; E. Johnson; L. Sarholt-Kristensen; S. Steenstrup; E. Gerritsen; C. J. M. Denissen; H. Keetels; J. Politiek; N. Hayashi; I. Sakamoto

1990-01-01

196

Shear thinning near the critical point of xenon  

NASA Astrophysics Data System (ADS)

We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span a wide range of reduced shear rate: 10-3xenon at amplitudes 3?m??? , C? depends also on both x0 and ? . The data were compared with numerical calculations based on the Carreau-Yasuda relation for complex fluids: ?(??)/?(0)=[1+A?|???|]-x?/(3+x?) , where x?=0.069 is the critical exponent for viscosity and mode-coupling theory predicts A?=0.121 . For xenon we find A?=0.1370.029 , in agreement with the mode coupling value. Remarkably, the xenon data close to the critical temperature Tc were independent of the cooling rate (both above and below Tc ) and these data were symmetric about Tc to within a temperature scale factor. The scale factors for the magnitude of the oscillators response differed from those for the oscillators phase; this suggests that the surface tension of the two-phase domains affected the drag on the screen below Tc .

Berg, Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

2008-04-01

197

Isotopic signature of atmospheric xenon released from light water reactors  

Microsoft Academic Search

A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The isotopic activity ratios of 135Xe, 133mXe, 133Xe and 131mXe are of interest for distinguishing nuclear explosion sources from civilian releases. Simulations of light water reactor (LWR) fuel burn-up through three operational reactor

Martin B. Kalinowski; Christoph Pistner

2006-01-01

198

Iodine-xenon studies of Bjurbole and Parnallee using RELAX  

Microsoft Academic Search

Iodine-xenon analyses of chondrules from the Bjurble L4 and Parnallee LL3.6 meteorites have been made using a continuous wave laser microprobe and the resonance ionisation mass spectrometer RELAX. The excess 129Xe content released from the Bjurble chondrule is lower than previous stepped-heating studies have found, suggesting that the technique does not completely degas the samples. Nonetheless, clear isochrons were produced,

J. D. Gilmour; R. D. Ash; R. Hutchison; J. C. Bridges; I. C. Lyon; G. Turner

1995-01-01

199

Regional Cerebral Blood Flow Estimated by 133 Xenon Inhalation  

Microsoft Academic Search

Regional Cerebral Blood Flow Estimated by Xenon Inhalation A method is described for estimating the clearance rate and fractional blood flow of the fast (gray matter) compartment of the brain from the first ten minutes of 133Xe clearance curves, following a one-minute inhalation. Computer-simulated data were used to test the adequacy of the two-compartmental model employed, and to evaluate

WALTER D. OBRIST; HOWARD K. THOMPSON; SHAN WANG; WILLIAM E. WILKINSON

1975-01-01

200

Gas Phase Xenon131 Quadrupolar Splitting at High Magnetic Fields  

Microsoft Academic Search

At very high magnetic fields strengths (14 Tesla and higher) the xenon-131 gas phase NMR spectrum shows a well resolved quadrupolar splitting. Quadrupolar coupling between a non-spherical (S>1\\/2) nuclei and an electric field gradient will occur when the electrical isotropy of the surrounding electron cloud is disturbed. The experimental results suggest that the origin of the observed splitting in the

Thomas Meersmann

1998-01-01

201

Cryogenic Technology Development For The MEG Liquid Xenon Calorimeter  

SciTech Connect

Cryogenic key technologies have been developed for the muon rare decay experiment (MEG) at the Paul Scherrer Institute, Switzerland. These technologies are the high power pulse tube cryocooler for precise temperature and pressure control of liquid xenon in the calorimeter, a purification system with a cryogenic liquid pump and a cryogenic dewar with 1000 L storage capacity. The paper describes the general concepts and the first test results of each technology. All the results imply a promising performance for the coming MEG experiment.

Haruyama, Tomiyoshi [KEK, High Energy Accelerator Research Organization 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2008-02-21

202

Frequency-dependent viscosity of xenon near the critical point  

NASA Astrophysics Data System (ADS)

We used a novel, overdamped oscillator aboard the Space Shuttle to measure the viscosity ? of xenon near its critical density ?c and temperature Tc. In microgravity, useful data were obtained within 0.1 mK of Tc, corresponding to a reduced temperature t=(T-Tc)/Tc=310-7. Because they avoid the detrimental effects of gravity at temperatures two decades closer to Tc than the best ground measurements, the data directly reveal the expected power-law behavior ?~t-?z?. Here ? is the correlation length exponent, and our result for the viscosity exponent is z?=0.0690+/-0.0006. (All uncertainties are one standard uncertainty.) Our value for z? depends only weakly on the form of the viscosity crossover function, and it agrees with the value 0.067+/-0.002 obtained from a recent two-loop perturbation expansion [H. Hao, R.A. Ferrell, and J.K. Bhattacharjee, (unpublished)]. The measurements spanned the frequency range 2 Hz<=f<=12 Hz and revealed viscoelasticity when t<=10-5, further from Tc than predicted. The viscoelasticity's frequency dependence scales as Af?, where ? is the fluctuation-decay time. The fitted value of the viscoelastic time-scale parameter A is 2.0+/-0.3 times the result of a one-loop perturbation calculation. Near Tc, the xenon's calculated time constant for thermal diffusion exceeded days. Nevertheless, the viscosity results were independent of the xenon's temperature history, indicating that the density was kept near ?c by judicious choices of the temperature versus time program. Deliberately bad choices led to large density inhomogeneities. At t>10-5, the xenon approached equilibrium much faster than expected, suggesting that convection driven by microgravity and by electric fields slowly stirred the sample.

Berg, Robert F.; Moldover, Michael R.; Zimmerli, Gregory A.

1999-10-01

203

Intermittent exposure to xenon protects against gentamicin-induced nephrotoxicity.  

PubMed

Aminoglycoside antibiotics, especially gentamicin, are widely used to treat Gram-negative infections due to their efficacy and low cost. Nevertheless the use of gentamicin is limited by its major side effect, nephrotoxicity. Xenon (Xe) provided substantial organoprotective effects in acute injury of the brain and the heart and protected against renal ischemic-reperfusion injury. In this study, we investigated whether xenon could protect against gentamicin-induced nephrotoxicity. Male Wistar rats were intermittently exposed to either 70% xenon or 70% nitrogen (N2) balanced with 30% oxygen before and during gentamicin administration at a dose of 100 mg/kg for 7 days to model gentamicin-induced kidney injury. We observed that intermittent exposure to Xe provided morphological and functional renoprotection, which was characterized by attenuation of renal tubular damage, apoptosis, and oxidative stress, but not a reduction in inflammation. We also found that Xe pretreatment upregulated hypoxia-inducible factor 2? (HIF-2?) and its downstream effector vascular endothelial growth factor, but not HIF-1?. With regard to the three HIF prolyl hydroxylases, Xe pretreatment upregulated prolyl hydroxylase domain-containing protein-2 (PHD2), suppressed PHD1, and had no influence on PHD3 in the rat kidneys. Pretreatment with Xe also increased the expression of miR-21, a microRNA known to have anti-apoptotic effects. These results support Xe renoprotection against gentamicin-induced nephrotoxicity. PMID:23737979

Jia, Ping; Teng, Jie; Zou, Jianzhou; Fang, Yi; Jiang, Suhua; Yu, Xiaofang; Kriegel, Alison J; Liang, Mingyu; Ding, Xiaoqiang

2013-05-30

204

Data analysis on XENON100 detector searching for WIMP  

NASA Astrophysics Data System (ADS)

The XENON100 detector is a dual-phase xenon time projection chamber (LXeTPC) installed underground at the Laboratori Nazionali del Gran Sasso (Italy) and used to search for dark matter in the form of weakly interacting massive particles (WIMPs) by simultaneously measuring the scintillation and ionization signals produced by nuclear recoils. The 62 kg LXeTPC is instrumented by 178 PMTs and surrounded by a 99 kg Lxe active veto with 64 PMTs. XENON100 has set the most stringent limits on WIMP-nucleon interaction cross section to date, above 7E-45cm^2 at 90% C.L., and continues to accrue blinded data towards a first robust discovery. We present the analysis techniques developed for the experiment and detail data selection procedures, quality cuts and efficiencies, as well the unblinding procedures for the experiment. Finally the methods for establishing presence of signal or for establishing a limit on interaction cross-section for WIMPs with matter are described.

Rizzo, Alfio

2012-03-01

205

Screen for Carbon Dioxide.  

ERIC Educational Resources Information Center

|Presents a set of laboratory experiments that can assist students in the detection of carbon dioxide. Offers a variation of the supported drop method of carbon dioxide detection that provides readily visible positive results. Includes background information on carbon dioxide. (ML)|

Foster, John; And Others

1986-01-01

206

Nitrogen dioxide detection  

DOEpatents

Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.

Sinha, Dipen N. (Los Alamos, NM); Agnew, Stephen F. (Los Alamos, NM); Christensen, William H. (Buena Park, CA)

1993-01-01

207

Deactivation of xenon atoms in the 6s resonant state in collisions with xenon and helium atoms  

SciTech Connect

The absorption probing method was used to investigate collisional deactivation of the 6s[3/2]{sub 1}{sup 0}({sup 3}P{sub 1}) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the following plasma-chemical reactions: Xe* + Xe + He {yields} Xe{sub 2}* + He [(2.1 {+-} 0.2) x 10{sup -32} cm{sup 6}s{sup -1}], Xe* + 2He {yields} HeXe* + He (less than 10{sup -35} cm{sup 6}s{sup -1}), and Xe* + He {yields} products + He (less than 3 x 10{sup -15} cm{sup 3}s{sup -1}). (active media)

Zayarnyi, D A; Semenova, Ludmila V; Ustinovskii, N N; Kholin, I V; Chugunov, A Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1999-02-28

208

Deactivation of the xenon atom in the 6s metastable state in collisions with xenon and helium atoms  

SciTech Connect

The absorption probing method was used to investigate collisional deactivation of the metastable 6s[3/2]{sub 2}{sup 0}({sup 3}P{sub 2}) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the plasma-chemical reactions Xe*+Xe+He {yields} Xe{sub 2}*+He [(1.7 {+-}0.2) x10{sup -32} cm{sup 6} s{sup -1}], Xe*+2He{yields} HeXe*+He (less than 3 x 10{sup -35} cm{sup 6} s{sup -1}), and Xe*+He{yields} products+He (less than 10{sup -15} cm{sup 3} s{sup -1}). (active media)

Zayarnyi, D A; Semenova, Ludmila V; Ustinovskii, N N; Kholin, I V; Chugunov, A Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1998-03-31

209

Oxide and oxide fluorides of xenon(IV) and new developments in xenon(II), and krypton(II) chemistry  

Microsoft Academic Search

This Thesis extends the fundamental chemistry of the noble-gas elements, namely, xenon and krypton. More specifically, the chemistry of Xe(IV) has been extended by the synthesis and characterization of Xe(IV) oxide and oxide fluoride derivatives. The syntheses of XeOF2, F2OXeN?CCH 3, and XeOF2 ˙nHF and their structural characterizations are described. All three compounds are endothermic and explosive at temperatures approaching

David S Brock

2011-01-01

210

Method for the simultaneous preparation of radon-211, xenon-125, xenon-123, astatine-211, iodine-125 and iodine-123  

Microsoft Academic Search

The invention relates to a practical method for commercially producing radiopharmaceutical activities and, more particularly, relates to a method for the preparation of about equal amount of Radon-211 (²¹¹Rn) and Xenon-125 (¹²⁵Xe) including a one-step chemical procedure following an irradiation procedure in which a selected target of Thorium (²³²Th) or Uranium (²³⁸U) is irradiated. The disclosed method is also effective

S. Mirzadeh; R. M. Lambrecht

1985-01-01

211

Adhesion molecules  

PubMed Central

Adhesion molecules are known to -be important components of an active T-cell mediated immune response. Signals generated at a site of inflammation cause circulating T cells to respond by rolling, arrest and then transmigration through the endothelium, all of which are mediated by adhesion molecules. Consequently, strategies have been developed to treat immune disorders with specific antibodies that block the interaction of adhesion molecules. However, the therapeutic effects of such remedies are not always achieved. Our recent investigations have revealed that intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) work together with chemokines to induce immunosuppression mediated by Mesenchymal stem cells (MSCs), thus demonstrating the dual role of adhesion molecules in immune responses. Since MSCs represent an important component of the stromal cells in an inflammatory microenvironment, our findings provide novel information for understanding the regulation of immune responses and for designing new strategies to treat immune disorders.

Ren, Guangwen; Roberts, Arthur I

2011-01-01

212

THE CHLOROPHYLL-CARBON DIOXIDE RATIO DURING PHOTOSYNTHESIS  

PubMed Central

Using a rapid spectrographic method of carbon dioxide measurement previously described by McAlister (1937) further studies on the time course of photosynthesis in the higher plant, wheat, variety Marquis, are herein reported. Of major importance in this work is the discovery of a pick-up of carbon dioxide in darkness immediately following a high rate of photosynthesis (see Figs. 3 and 4). This pick-up is believed to be due to the action of a carbon dioxide-combining intermediate; i.e., the "acceptor molecule" for carbon dioxide in photosynthesis. The conditions under which this phenomenon has so far been observed indicate that the intermediate is formed in relatively large quantities during the actual process of photosynthesis and not before. That the intermediate is chlorophyllous in nature is suggested by a simple stoichiometry of the order of unity that is found to exist between the number of carbon dioxide molecules taken up and the total number of chlorophyll molecules present in the plant. This is in opposition to the idea of a large photosynthetic unit of some 2000 chlorophyll molecules operating together in the reduction of 1 carbon dioxide molecule. Further studies of the induction phase under various conditions of previous dark rest and of carbon dioxide and light limitation are herein described. Employing the simple hypothesis that the number of carbon dioxide molecules not reduced during the induction period (induction loss) gives a measure of the number of elementary photosynthetic cycles unoperative or compensated for during induction together with the experimental fact that this induction loss is of the order of the total number of chlorophyll molecules present, these latter studies also indicate, in a less direct manner, that chlorophyll participates in photosynthesis as an individual molecule and not as part of a very large multimolecular chlorophyll unit. The fast dark reaction lasting about 1 minute (Fig. 7) required to reproduce both (a) the phenomena of induction in carbon dioxide assimilation and (b) the recovery of fluorescence of chlorophyll in leaves in darkness as observed by Franck and Wood (1936), demonstrates a close relationship between the fluorescence of chlorophyll and induction in photosynthesis. The rate of respiration (carbon dioxide production) of the higher plant, wheat, was measured under intense illumination and in the absence of carbon dioxide (to suppress assimilation). This value was found to be identical with the dark respirational rate measured before and after the light period, indicating very positively the absence of any direct effect of light on respiration.

McAlister, E. D.

1939-01-01

213

THE CHLOROPHYLL-CARBON DIOXIDE RATIO DURING PHOTOSYNTHESIS.  

PubMed

Using a rapid spectrographic method of carbon dioxide measurement previously described by McAlister (1937) further studies on the time course of photosynthesis in the higher plant, wheat, variety Marquis, are herein reported. Of major importance in this work is the discovery of a pick-up of carbon dioxide in darkness immediately following a high rate of photosynthesis (see Figs. 3 and 4). This pick-up is believed to be due to the action of a carbon dioxide-combining intermediate; i.e., the "acceptor molecule" for carbon dioxide in photosynthesis. The conditions under which this phenomenon has so far been observed indicate that the intermediate is formed in relatively large quantities during the actual process of photosynthesis and not before. That the intermediate is chlorophyllous in nature is suggested by a simple stoichiometry of the order of unity that is found to exist between the number of carbon dioxide molecules taken up and the total number of chlorophyll molecules present in the plant. This is in opposition to the idea of a large photosynthetic unit of some 2000 chlorophyll molecules operating together in the reduction of 1 carbon dioxide molecule. Further studies of the induction phase under various conditions of previous dark rest and of carbon dioxide and light limitation are herein described. Employing the simple hypothesis that the number of carbon dioxide molecules not reduced during the induction period (induction loss) gives a measure of the number of elementary photosynthetic cycles unoperative or compensated for during induction together with the experimental fact that this induction loss is of the order of the total number of chlorophyll molecules present, these latter studies also indicate, in a less direct manner, that chlorophyll participates in photosynthesis as an individual molecule and not as part of a very large multimolecular chlorophyll unit. The fast dark reaction lasting about 1 minute (Fig. 7) required to reproduce both (a) the phenomena of induction in carbon dioxide assimilation and (b) the recovery of fluorescence of chlorophyll in leaves in darkness as observed by Franck and Wood (1936), demonstrates a close relationship between the fluorescence of chlorophyll and induction in photosynthesis. The rate of respiration (carbon dioxide production) of the higher plant, wheat, was measured under intense illumination and in the absence of carbon dioxide (to suppress assimilation). This value was found to be identical with the dark respirational rate measured before and after the light period, indicating very positively the absence of any direct effect of light on respiration. PMID:19873123

McAlister, E D

1939-05-20

214

Utility of silicon tetrafluoride as a catalyst of reactions with xenon difluoride: fluorinations of phenyl alkenes and benzaldehydes  

Microsoft Academic Search

Application of silicon tetrafluoride to fluorinations with xenon difluoride as a catalyst is investigated. It was found that vic-difluorination of phenyl alkenes and transformation of benzaldehydes to difluoromethoxybenzenes using xenon difluoride are enhanced by silicon tetrafluoride.

Masanori Tamura; Toshiyuki Takagi; Heng-dao Quan; Akira Sekiya

1999-01-01

215

Conformational behavior of dimethyl 5-methyl-1H,3H-pyrrolo[1,2-c][1,3]thiazole-6,7-dicarboxylate 2,2-dioxide isolated in low-temperature matrixes.  

PubMed

The structure of dimethyl 5-methyl-1H,3H-pyrrolo[1,2-c][1,3]thiazole-6,7-dicarboxylate 2,2-dioxide (PTD) was investigated in low-temperature noble gas matrixes (Ar, Kr, Xe), amorphous solid, and the crystalline state by infrared spectroscopy and computational methods. The geometry of PTD conformers is defined by the orientation of two methyl ester groups, which may adopt pseudo-trans or pseudo-cis positions in relation to the pyrrolo-thiazole system. For both methyl ester groups, the latter arrangement was predicted by the calculations to be energetically the most favorable in the isolated molecule. The envelope form of the thiazolidine ring is present in all conformers, with the sulfur atom placed in the apex position, while the pyrrole ring is almost planar. Three types of conformers differing in the orientation of the methyl ester groups relative to the pyrrolo-thiazole system (cis/cis, trans/cis, cis/trans) were identified in the matrixes. The cis/cis forms were found to be the most stable ones in both gaseous state and argon matrixes. On the other hand, the more polar trans/cis forms were found to be stabilized in the more polarizable krypton and xenon matrixes as well as in the neat amorphous and crystalline phases. On the basis of annealing experiments, performed in argon and xenon matrixes up to 35 and 68 K, respectively, conformational changes preceding the aggregation of the compound are suggested. PMID:16706411

Kaczor, A; Pinho e Melo, T M V D; Soares, M I L; Fausto, R

2006-05-25

216

Monte Carlo calculation of ion, electron, and photon spectra of xenon atoms in x-ray free-electron laser pulses  

NASA Astrophysics Data System (ADS)

When atoms and molecules are irradiated by an x-ray free-electron laser (XFEL), they are highly ionized via a sequence of one-photon ionization and relaxation processes. To describe the ionization dynamics during XFEL pulses, a rate equation model has been employed. Even though this model is straightforward for the case of light atoms, it generates a huge number of coupled rate equations for heavy atoms like xenon, which are not trivial to solve directly. Here, we employ the Monte Carlo method to address this problem and we investigate ionization dynamics of xenon atoms induced by XFEL pulses at a photon energy of 4500 eV. Charge-state distributions, photoelectron and Auger electron spectra, and fluorescence spectra are presented for x-ray fluences of up to 1013 photons/?m2. With the photon energy of 4500 eV, xenon atoms can be ionized up to +44 through multiphoton absorption characterized by sequential one-photon single-electron interactions.

Son, Sang-Kil; Santra, Robin

2012-06-01

217

The mechanism and kinetics of energy transfer processes in Xe-CCl4-M (M=CO, CO2) mixtures irradiated by xenon resonance light  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of energy transfer from the Xe(6s[3/2]1) resonance state to CO and CO2 molecules have been investigated by XeCl(B-X) (?max=308 nm) fluorescence intensity measurements at stationary conditions in Xe-CCl4-M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these processes occur in two- and three-body reactions: Xe(6s[3/2]10)+M-->products Xe(6s[3/2]10)+M+Xe-->products. The two-body rate constants for above reactions have been found to be (0.7+/-0.2)x10-10 and (4.9+/-0.4)x10-10 cm3 s-1 for CO and CO2, respectively. The three-body rate constants have been found to be (3+/-1)x10-29 and (2.4+/-0.3)x10-28 cm6 s-1 for CO and CO2, respectively. It has been shown that the third order reaction is a very effective channel of xenon excited atoms decay at high xenon pressures (P50 Torr).

Wojciechowski, K.

1999-01-01

218

Single Molecules  

NSDL National Science Digital Library

A new molecular science journal, Single Molecules, from Wiley Interscience, "will provide researchers with a broad overview of current methods and techniques, recent applications and shortcomings of present techniques in the field of single molecules." With temporary free access, the journal's latest issue contains a few full-text articles, with more articles being regularly added. This journal is currently calling for papers.

219

Interstellar molecules  

NASA Astrophysics Data System (ADS)

Complex molecules cycling from circumstellar envelopes through various phases of interstellar matter in the Milky Way are considered. Approximately 65 of the interstellar species detected so far are considered to be organic molecules. By interpreting molecular signatures, it is possible to determine the chemical composition, temperature, mass, internal motions, and evolutionary fate of a dark interstellar cloud.

Verschuur, Gerrit L.

1992-04-01

220

Facile xenon capture and release at room temperature using a metal-organic framework: a comparison with activated charcoal.  

PubMed

Two well-known metal-organic frameworks (MOF-5, NiDOBDC) were synthesized and studied for facile xenon capture and separation. Our results indicate that NiDOBDC adsorbs significantly more xenon than MOF-5, and is more selective for xenon over krypton than activated carbon. PMID:21956410

Thallapally, Praveen K; Grate, Jay W; Motkuri, Radha Kishan

2011-09-29

221

XENON-133 IN CALIFORNIA, NEVADA, AND UTAH FROM THE CHERNOBYL ACCIDENT (JOURNAL VERSION)  

EPA Science Inventory

The accident at the Chernobyl nuclear reactor in the USSR introduced numerous radioactive nuclides into the atmosphere, including the noble gas xenon-133. EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, detected xenon-133 from the Chernobyl accident in air sampl...

222

In vivo Mapping of Local Cerebral Blood Flow by Xenon-Enhanced Computed Tomography  

Microsoft Academic Search

A noninvasive technique has been developed to measure and display local cerebral blood flow (LCBF) in vivo. In this procedure, nonradioactive xenon gas is inhaled and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential computerized tomography. The time-dependent xenon concentrations in various anatomical units in the brain are used to derive both the local

David Gur; Walter F. Good; Sidney K. Wolfson; Howard Yonas; Leonard Shabason

1982-01-01

223

Rapid curing of bonding composite with a xenon plasma arc light  

Microsoft Academic Search

The use of light-cured orthodontic adhesives is an increasingly popular method for the bonding of orthodontic brackets. However, one of the disadvantages of light-cured adhesives is their long curing times. The xenon plasma arc curing light is purported to dramatically reduce the required curing time. The purpose of this study was to test the efficiency of a xenon plasma arc

Larry J. Oesterle; Sheldon M. Newman; W. Craig Shellhart

2001-01-01

224

INTEGRAL AND SPECTRAL CHARACTERISTICS OF ATON STATIONARY PLASMA THRUSTER OPERATING ON KRYPTON AND XENON  

Microsoft Academic Search

The integral characteristics of an ATON (1) stationary plasma thruster operating on xenon and krypton are investigated. It is shown that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower than those with xenon. An efficiency of ~60% was achieved with krypton for the specific impulse attaining

A. I. Bugrova; A. I. Morozov; A. S. Lipatov; A. M. Bishaev; V. K. Kharchevnikov; M. V. Kozintseva

225

Helium, neon, argon, krypton and xenon in gas emanations from Yellowstone and Lassen volcanic National Parks  

Microsoft Academic Search

The abundance of helium, neon, argon, krypton and xenon were measured in gas emanations from thermal springs in Yellowstone National Park, Wyoming and Lassen National Park, California. The determinations were made using an isotope dilution procedure. The isotopic composition of argon and the relative abundances of argon, neon, krypton and xenon indicate that these gases originated from the atmosphere through

E. Mazor; G. J. Wasserburg

1965-01-01

226

Efficiency Analysis of a Hall Thruster Operating with Krypton and Xenon  

Microsoft Academic Search

Krypton has recently become the focus of attention in the Hall thruster community because of its relatively large specific impulse as compared to xenon and its potential to operate with comparable efficiencies. However, before krypton can be considered a viable propellant choice for missions, the performance gap between xenon and krypton must be reduced. A series of diagnostic measurements are

Jesse A. Linnell; Alec D. Gallimore

2006-01-01

227

Xenon treatment attenuates early renal allograft injury associated with prolonged hypothermic storage in rats.  

PubMed

Prolonged hypothermic storage elicits severe ischemia-reperfusion injury (IRI) to renal grafts, contributing to delayed graft function (DGF) and episodes of acute immune rejection and shortened graft survival. Organoprotective strategies are therefore needed for improving long-term transplant outcome. The aim of this study is to investigate the renoprotective effect of xenon on early allograft injury associated with prolonged hypothermic storage. Xenon exposure enhanced the expression of heat-shock protein 70 (HSP-70) and heme oxygenase 1 (HO-1) and promoted cell survival after hypothermia-hypoxia insult in human proximal tubular (HK-2) cells, which was abolished by HSP-70 or HO-1 siRNA. In the brown Norway to Lewis rat renal transplantation, xenon administered to donor or recipient decreased the renal tubular cell death, inflammation, and MHC II expression, while delayed graft function (DGF) was therefore reduced. Pathological changes associated with acute rejection, including T-cell, macrophage, and fibroblast infiltration, were also decreased with xenon treatment. Donors or recipients treated with xenon in combination with cyclosporin A had prolonged renal allograft survival. Xenon protects allografts against delayed graft function, attenuates acute immune rejection, and enhances graft survival after prolonged hypothermic storage. Furthermore, xenon works additively with cyclosporin A to preserve post-transplant renal function.-Zhao, H., Yoshida, A., Xiao, W., Ologunde, R., O'Dea, K. P., Takata, M., Tralau-Stewart, C., George, A. J. T., Ma, D. Xenon treatment attenuates early renal allograft injury associated with prolonged hypothermic storage in rats. PMID:23759444

Zhao, Hailin; Yoshida, Akira; Xiao, Wei; Ologunde, Rele; O'Dea, Kieran P; Takata, Masao; Tralau-Stewart, Catherine; George, Andrew J T; Ma, Daqing

2013-06-12

228

Comparative study of photodegradation of wood by a UV laser and a xenon light source  

Microsoft Academic Search

A detailed study of photodegradation of wood surfaces by xenon light source and a UV laser has been carried out. Silver birch, rubberwood, Scots pine and chir pine wood veneers were irradiated with a xenon light source or a 244nm argon ion laser. The changes in chemical structure of wood surfaces were monitored by UV resonance Raman (UVRR), photoacoustic Fourier

Krishna K. Pandey; Tapani Vuorinen

2008-01-01

229

Sensitivity Enhancement by Exchange Mediated MagnetizationTransfer of the Xenon Biosensor Signal  

SciTech Connect

Hyperpolarized xenon associated with ligand derivitized cryptophane-A cages has been developed as a NMR based biosensor. To optimize the detection sensitivity we describe use of xenon exchange between the caged and bulk dissolved xenon as an effective signal amplifier. This approach, somewhat analogous to 'remote detection' described recently, uses the chemical exchange to repeatedly transfer spectroscopic information from caged to bulk xenon, effectively integrating the caged signal. After an optimized integration period, the signal is read out by observation of the bulk magnetization. The spectrum of the caged xenon is reconstructed through use of a variable evolution period before transfer and Fourier analysis of the bulk signal as a function of the evolution time.

Garcia, Sandra; Chavez, Lana; Lowery, Thomas J.; Han, Song-I.; Wemmer, David E.; Pines, Alexander

2006-08-31

230

Martian xenon components in Shergotty mineral separates: Locations, sources and trapping mechanisms  

NASA Astrophysics Data System (ADS)

Isotopic signatures and concentrations of xenon have been measured in Shergotty mineral separates by laser step heating. Martian atmosphere and 'martian interior' xenon are present, as is a spallation component. Martian atmospheric xenon is 5-10 more concentrated in opaque minerals (magnetite, ilmenite, and pyrrhotite) and maskelynite than in pyroxenes, perhaps reflecting grain size variation. This is shown to be consistent with shock incorporation. A component consisting of solar xenon with a fission contribution, similar to components previously identified in martian meteorites and associated with the martian interior, is best defined in the pyroxene-dominated separates. This component exhibits a consistent 129Xe (129Xe/132Xe ?1.2) excess over solar/planetary (129Xe/132Xe ?1.04). We suggest that gas present in the melt, perhaps a mixture of interior xenon and martian atmosphere, was incorporated into the pyroxenes in Shergotty as the minerals crystallized.

Ocker, K. D.; Gilmour, J. D.

2004-12-01

231

Xenon in And at the End of the Tunnel of Bifunctional Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase  

SciTech Connect

A fascinating feature of some bifunctional enzymes is the presence of an internal channel or tunnel to connect the multiple active sites. A channel can allow for a reaction intermediate generated at one active site to be used as a substrate at a second active site, without the need for the intermediate to leave the safety of the protein matrix. One such bifunctional enzyme is carbon monoxide dehydrogenase/acetyl-CoA synthase from Moorella thermoacetica (mtCODH/ACS). A key player in the global carbon cycle, CODH/ACS uses a Ni-Fe-S center called the C-cluster to reduce carbon dioxide to carbon monoxide and uses a second Ni-Fe-S center, called the A-cluster, to assemble acetyl-CoA from a methyl group, coenzyme A, and C-cluster-generated CO. mtCODH/ACS has been proposed to contain one of the longest enzyme channels (138 A long) to allow for intermolecular CO transport. Here, we report a 2.5 A resolution structure of xenon-pressurized mtCODH/ACS and examine the nature of gaseous cavities within this enzyme. We find that the cavity calculation program CAVENV accurately predicts the channels connecting the C- and A-clusters, with 17 of 19 xenon binding sites within the predicted regions. Using this X-ray data, we analyze the amino acid composition surrounding the 19 Xe sites and consider how the protein fold is utilized to carve out such an impressive interior passageway. Finally, structural comparisons of Xe-pressurized mtCODH/ACS with related enzyme structures allow us to study channel design principles, as well as consider the conformational flexibility of an enzyme that contains a cavity through its center.

Doukov, T.I.; Blasiak, L.C.; Seravalli, J.; Ragsdale, S.W.; Drennan, C.L.; /MIT /SLAC, SSRL /Nebraska U.

2009-05-11

232

Xenon excimer emission from multicapillary discharges in direct current mode  

SciTech Connect

Microdischarges in xenon have been generated in a pressure range of 400-1013 mbar with a fixed flow rate of 100 sccm. These microdischarges are obtained from three metallic capillary tubes in series for excimer emission. Total discharge voltage is thrice as large as that of a single capillary discharge tube at current levels of up to 12 mA. Total spectral irradiance of vacuum ultraviolet (VUV) emission also increases significantly compared to that of the single capillary discharge. Further, the irradiance of the VUV emission is strongly dependent on pressure as well as the discharge current.

Lee, Byung-Joon; Rahaman, Hasibur; Nam, Sang Hoon [Pohang Accelerator Laboratory, Pohang, Kyungbuk 790-784 (Korea, Republic of); Giapis, Konstantinos P. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); Iberler, Marcus; Jacoby, Joachim [Institute of Applied Physics, Goethe University, Max-von-Laue-St. 1, 60438 Frankfurt am Main (Germany); Frank, Klaus [Physics Department I, F.A., University of Erlangen-Nuremberg, D-91058 Erlangen (Germany)

2011-08-15

233

Mechanism for transient migration of xenon in UO2  

NASA Astrophysics Data System (ADS)

In this letter, we report recent work on atomistic modeling of diffusion migration events of the fission gas product xenon in UO2 nuclear fuel. Under nonequilibrium conditions, Xe atoms can occupy the octahedral interstitial site, in contrast to the thermodynamically most stable uranium substitutional site. A transient migration mechanism involving Xe and two oxygen atoms is identified using basin constrained molecular dynamics employing a Buckingham type interatomic potential. This mechanism is then validated using density functional theory calculations using the nudged elastic band method. An overall reduction in the migration barrier of 1.6-2.7 eV is obtained compared to vacancy-mediated diffusion on the uranium sublattice.

Liu, X.-Y.; Uberuaga, B. P.; Andersson, D. A.; Stanek, C. R.; Sickafus, K. E.

2011-04-01

234

Microdischarges of xenon sustained by microwaves: Determination of scaling laws  

SciTech Connect

The threshold conditions to maintain millimeter and submillimeter-size discharges of xenon with microwaves are experimentally determined. The threshold electric field required to sustain the plasma is reported as a function of gas pressure. The influence of the size of the dielectric cell in which the discharge is produced is also shown. The scaling laws are deduced from the threshold electric field measurements, assuming a few additional simplifying assumptions. The results are compared with data obtained with argon discharges sustained by surface waves in capillary tubes and the hypotheses assumed for the calculations are discussed.

Lacoste, A.; Maulat, O.; Latrasse, L.; Arnal, Y.; Pelletier, J. [Laboratoire Elaboration par Procedes Magnetiques (EPM), UPR CNRS 9033 ENSHMG, BP 95, 38402 Saint Martin d'Heres Cedex (France)

2005-04-04

235

Xenon ion beam characterization in a helicon double layer thruster  

SciTech Connect

A current-free electric double layer is created in a helicon double layer thruster operating with xenon and compared to a recently developed theory. The Xe{sup +} ion beam formed by acceleration through the potential drop of the double layer is characterized radially using an electrostatic ion energy analyzer. For operating conditions of 500 W rf power, 0.07 mTorr gas pressure, and a maximum magnetic field of 125 G, the measured beam velocity is about 6 km s{sup -1}, the beam area is about 150 cm{sup 2}, and the measured beam divergence is less than 6 deg.

Charles, C.; Boswell, R. W.; Lieberman, M. A. [Space Plasma, Power, and Propulsion Group, Research School of Physical Sciences and Engineering, Australian National University, Australian Capital Territory 0200 (Australia)

2006-12-25

236

Shear thinning near the critical point of xenon.  

PubMed

We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span a wide range of reduced shear rate: 10(-3)xenon at amplitudes 3 micromgamma tau , C gamma depends also on both x 0 and omega . The data were compared with numerical calculations based on the Carreau-Yasuda relation for complex fluids: eta(gamma)/eta(0)=[1+A gamma|gamma tau|]-x eta/(3+x eta) , where x eta=0.069 is the critical exponent for viscosity and mode-coupling theory predicts A gamma=0.121 . For xenon we find A gamma=0.137+/-0.029 , in agreement with the mode coupling value. Remarkably, the xenon data close to the critical temperature Tc were independent of the cooling rate (both above and below Tc ) and these data were symmetric about Tc to within a temperature scale factor. The scale factors for the magnitude of the oscillator's response differed from those for the oscillator's phase; this suggests that the surface tension of the two-phase domains affected the drag on the screen below Tc . PMID:18517587

Berg, Robert F; Moldover, Michael R; Yao, Minwu; Zimmerli, Gregory A

2008-04-17

237

Interstellar Molecules  

ERIC Educational Resources Information Center

|Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)|

Solomon, Philip M.

1973-01-01

238

Adhesion molecules  

Microsoft Academic Search

Adhesion molecules are cell membrane receptors that mediate cell-to-cell and cell-to-matrix communication in macroorganisms. Because the receptors and ligands involved are non-diffusible, adhesion molecules are capable of organ, tissue and cell specific regulation under physiological and pathophysiological conditions. Consequently, this local (positional) regulatory system has the ability to alter\\/modify\\/tune systemic regulatory signals and generate signals locally in order to match

Istvan Berczi; Andor Szentivanyi

2003-01-01

239

Enumerating molecules.  

SciTech Connect

This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecular design, and combinatorial library design purposes. This review is to appear as a chapter in Reviews in Computational Chemistry volume 21 edited by Kenny B. Lipkowitz.

Visco, Donald Patrick, Jr. (, . Tennessee Technological University, Cookeville, TN); Faulon, Jean-Loup Michel; Roe, Diana C.

2004-04-01

240

Temperature VS Carbon Dioxide  

NSDL National Science Digital Library

In this activity, students examine the relationship between carbon dioxide levels and global temperature change by studying a graph of these two variables. They will discover that by using data from ice cores, scientists can determine temperature and carbon dioxide levels in the air as far back as a hundred thousand years in the past. The students try to predict which variable is the independent one and then make a graph of temperature change and carbon dioxide levels. After making their graph, students describe the relationship between temperature and carbon dioxide levels in the atmosphere to determine if their predictions were correct.

241

Local structure of xenon adsorbed in the nanospaces of zeolites as studied by high-pressure 129Xe NMR.  

PubMed

Pressure (0-10 MPa) and local density dependence of 129Xe NMR chemical shift of xenon in various microporous materials was investigated using an in situ high-pressure probe. The density dependence of the chemical shift was analyzed using virial expansion of the chemical shift by xenon density. Results indicate that the second virial coefficient depends on the pore size and shape, and that the void space affects xenon-xenon interaction in both microporous and mesoporous materials. Furthermore, to interpret the magnitude of the virial coefficient in terms of the local structure of the adsorbed xenon, we analyzed the local structure of adsorbed xenon in molecular sieve 5A using Xe(n) clusters, thereby allowing description of the density dependence of the chemical shift. We also demonstrated the cluster model's validity by applying it to molecular sieves 13X and ZSM-5. The latter showed that the adsorbed xenon exists as a xenon monomer up to the filling of about 0.6 in micropores. Larger xenon clusters up to n = 4 have been grown with increasing filling of xenon. According to analyses using the Xe(n) cluster model, the second virial coefficient is related closely with the xenon cluster size, which contributes greatly to the chemical shift in the low loading region. PMID:19817046

Omi, Hironori; Ueda, Takahiro; Kato, Noriko; Miyakubo, Keisuke; Eguchi, Taro

2006-09-01

242

Secondary shock formation in xenon-nitrogen mixtures  

SciTech Connect

The expansion of shock waves has been studied in mediums with different opacities and heat capacities, varied in systematic ways by mixing xenon with nitrogen keeping the mass density constant. An initial shock is generated through the brief (5 ns) deposition of laser energy (5 J) on the tip of a pin surrounded by the xenon-nitrogen mixture. The initial shock is spherical, radiative, with a high Mach number, and it sends a supersonic radiatively driven heat wave far ahead of itself. The heat wave rapidly slows to a transonic regime and when its Mach number drops to {approx}2 with respect to the downstream plasma, the heat wave becomes of the ablative type, driving a second shock ahead of itself to satisfy mass and momentum conservation in the heat wave reference frame. The details of this sequence of events depend, among other things, on the opacity and heat capacity of the surrounding medium. Second shock formation is observed over the entire range from 100% Xe mass fraction to 100% N{sub 2}. The formation radius of the second shock as a function of Xe mass fraction is consistent with an analytical estimate.

Hansen, J. F.; Edwards, M. J.; Froula, D. H.; Edens, A. D.; Gregori, G.; Ditmire, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sandia National Labs, Albuquerque, New Mexico 87185 (United States); LRC-Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); University of Texas at Austin, Austin, Texas 78712 (United States)

2006-11-15

243

Cryogenic Large Liquid Xenon Detector for Dark Matter Searches  

NASA Astrophysics Data System (ADS)

Observation of rotational curve of spiral galaxies shows that a large fraction (~23%) of the mass density of the universe is unaccounted for. Such a significant percentage of missing dark matter suggests that the universe may consist of new types of elementary particles. A compelling explanation for the new particles is the existence of Weakly Interacting Massive Particles (WIMPs), which are non-baryonic particles characterized by particle physics theories beyond the Standard Model. WIMPs are believed to only interact through the weak force and gravity; hence the interaction cross section with ordinary matter is extremely small. Therefore, experimental techniques that combine low radioactivity, low energy thresholds, efficient discrimination against electronic recoil backgrounds, and scalability to large detector masses can only be performed at a deep underground environment where the interference of cosmic rays is obviated. In this paper, we report a cryogenic large liquid xenon detector for dark matter searches at Sanford Lab (Davis Cavern) in the Homestake Mine, USA. The goal of the large underground xenon (LUX) dual-phase detector is to clearly detect (or exclude) WIMPs with a spin independent cross-section per nucleon of 7 10-46 cm2, equivalent to ~0.5 events/100 kg/month in an inner 100 kg fiducial volume (FV) of a 300 kg LXe detector.

Mei, D.-M.; Akerib, D. S.; Bai, X.-H.; Bedikian, S.; Bernard, E.; Bolozdynya, A.; Bradley, A.; Cahn, S. B.; Camp, C.; Carmona-Benitez, M. C.; Carr, D.; Chapman, J. J.; Clark, K.; Classen, T.; Coffey, T.; Curioni, A.; Dahl, E.; Dazeley, S.; de Viveiros, L.; Dragowsky, M.; Druszkiewicz, E.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gibson, K. R.; Hall, C.; Hanhardt, M.; Holbrook, B.; Ihm, M.; Jacobsen, R. G.; Kastens, L.; Kazkaz, K.; Lander, R.; Lee, C.; Leonard, D.; Lesko, K.; Lyashenko, A.; Malling, Dc; Mannino, R.; Marquez, Z.; McKinsey, D.; Mock, J.; Morii, M.; Nelson, H.; Nokkel, Ja; Pangilinan, M.; Phelps, P.; Rodionov, A.; Roberts, P.; Shutt, T.; Skulski, W.; Sofka, Cj; Sorensen, P.; Spaans, J.; Stiegler, T.; Svoboda, R.; Sweany, M.; Thomson, J.; Tripathi, M.; Verbus, J. R.; Walsh, N.; Webb, R.; White, Jt; Wlasenko, M.; Wolfs, Flh; Woods, M.; Zhang, C.

2012-12-01

244

Lifetime Modeling of Xenon Hollow Cathodes Used in Electric Propulsion  

NASA Astrophysics Data System (ADS)

Xenon hollow cathodes with barium calcium aluminate impregnated tungsten inserts are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The entitlement lifetime of a thermionic emission cathode impregnated with barium-containing compounds is determined by the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. A thermodynamic model of the chemical process of barium evolution has been adapted from that of Lipeles and Kan^1. The model accounts for the diffusion of barium and barium oxide gas through the xenon expellant and loss of barium-containing gases through the cathode orifice as well as loss by condensation. Axial barium density profiles are presented and cathode lifetimes are estimated. Results of the model are compared with experimental results from the extensive hollow cathode life test database at the NASA Glenn Research Center. 1. Lipeles, R.A., Kan, H.K.A., Appl. Surf. Sci. 16, 189(1983).

Kovaleski, Scott

2001-10-01

245

The Carbamate Reaction of Carbon Dioxide with GlycylGlycine  

Microsoft Academic Search

The carbamate equilibrium between carbon dioxide and glycyl-glycine is believed to form a model for the similar, but more complex, equilibria of carbon dioxide with the terminal alpha -NH2 groups of the haemoglobin molecule. In the case of glycyl-glycine the carbamate equilibrium constant, Kc, has been estimated from the fall, after one second, in the concentration of dissolved CO2 when

F. J. W. Roughton; L. Rossi-Bernardi

1966-01-01

246

Numerical study on xenon positive column discharges of mercury-free lamp  

SciTech Connect

In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells.

Ouyang, Jiting; He, Feng; Miao, Jinsong; Wang, Jianqi; Hu, Wenbo [School of Science, Beijing Institute of Technology, P.O. Box 327, Beijing 100081 (China); Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China)

2007-02-15

247

Irradiated Xenon Isotopic Ratio Measurement for Failed Fuel Detection and Location in Fast Reactor  

NASA Astrophysics Data System (ADS)

The accuracy of xenon isotopic ratio burn-up calculations used for failed fuel identification was evaluated by an irradiation test of xenon tag gas samples in the Joyo test reactor. The experiment was carried out using pressurized steel capsules containing unique blend ratios of stable xenon tag gases in an on-line creep rupture experiment in Joyo. The tag gas samples were irradiated to total neutron fluences of 1.6 to 4.8 1026 n/m2. Laser resonance ionization mass spectrometry was used to analyze the cover gas containing released tag gas diluted to isotopic ratios of 100 to 102 ppb. The isotopic ratios of xenon tag gases after irradiation were calculated using the ORIGEN2 code. The neutron cross sections of xenon nuclides were based on the JENDL-3.3 library. These cross sections were collapsed into one group using the neutron spectra of Joyo. The comparison of measured and calculated xenon isotopic ratios provided C/E values that ranged from 0.92 to 1.10. The differences between calculation and measurement were considered to be mainly due to the measurement errors and the xenon nuclide cross section uncertainties.

Ito, Chikara; Iguchi, Tetsuo; Harano, Hideki

2009-08-01

248

Revisiting XENON100's constraints (and signals?) for low-mass dark matter  

NASA Astrophysics Data System (ADS)

Although observations made with the CoGeNT and CDMS experiments have been interpreted as possible signals of low-mass ( ~ 710 GeV) dark matter particles, constraints from the XENON100 collaboration appear to be incompatible with this hypothesis, at least at face value. In this paper, we revisit XENON100's constraint on dark matter in this mass range, and consider how various uncertainties and assumptions made might alter this conclusion. We also note that while XENON100's two nuclear recoil candidates each exhibit very low ratios of ionization-to-scintillation signals, making them difficult to attribute to known electronic or neutron backgrounds, they are consistent with originating from dark matter particles in the mass range favored by CoGeNT and CDMS. We argue that with lower, but not implausible, values for the relative scintillation efficiency of liquid xenon (Leff), and the suppression of the scintillation signal in liquid xenon at XENON100's electric field (Snr), these two events could consistently arise from dark matter particles with a mass and cross section in the range favored by CoGeNT and CDMS. If this interpretation is correct, we predict that the LUX experiment, with a significantly higher light yield than XENON100, should observe dark matter induced events at an observable rate of ~ 324 per month.

Hooper, Dan

2013-09-01

249

Studies of atmospheric molecules by multiphoton spectroscopy  

Microsoft Academic Search

Carbon dioxide presents a great challenge to spectroscopy because of its propensity toward dissociation in all of its excited states. Multiphoton ionization spectroscopy is usually not applicable to the study of dissociating molecules because the dissociation competes effectively with ionization, resulting in no signal. We reasoned, however, that with high enough laser fluence, ionization could compete with dissociation in the

Johnson

1991-01-01

250

The mechanism and kinetics of energy transfer processes in the Xe-CCl4-M (M=CH4, C2H2, C2H4, C2H6 C3H6 and C3H8) mixtures irradiated by xenon resonance light  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of energy transfer from Xe(6s[3/2]1) resonance state (E=8.44 eV) to selected hydrocarbon molecules have been investigated by XeCl(B-X) (?max=308 nm) fluorescence intensity measurements at stationary conditions in Xe-CCl4-M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these process occur in the two- and three-body reactions: Xe(6s[3/2]10)+M-->products, Xe(6s[3/2]10+M+Xe-->products. The two- and three-body rate constants for these reactions have been found (see Table 1 ). It has been shown that the third order reaction is a very effective channel of energy transfer from xenon excited atoms to hydrocarbons at xenon pressures above 50 Torr in all investigated systems.

Wojciechowski, K.

1999-01-01

251

Production of Carbon Dioxide  

NSDL National Science Digital Library

In this chemistry activity, learners use common chemicals to produce carbon dioxide and observe its properties. This resource includes brief questions for learners to answer after the experiment. Use this activity to introduce learners to carbon dioxide and its use as a fire extinguisher. Note: this activity involves an open flame.

House, The S.

2013-05-15

252

Carbon Dioxide and Climate.  

ERIC Educational Resources Information Center

The amount of carbon dioxide in the atmosphere is increasing at a rate that could cause significant warming of the Earth's climate in the not too distant future. Oceanographers are studying the role of the ocean as a source of carbon dioxide and as a sink for the gas. (Author/BB)

Brewer, Peter G.

1978-01-01

253

Carbon Dioxide Reduction System.  

National Technical Information Service (NTIS)

An automatically operated carbon dioxide reduction system was developed, fabricated and tested. The system was designed to reduce the carbon dioxide equivalent to that produced by one man, and to produce carbon and oxygen. A system such as this is require...

H. Chandler

1964-01-01

254

Carbon Dioxide Fountain  

ERIC Educational Resources Information Center

|This article presents the development of a carbon dioxide fountain. The advantages of the carbon dioxide fountain are that it is odorless and uses consumer chemicals. This experiment also is a nice visual experiment that allows students to see evidence of a gaseous reagent being consumed when a pressure sensor is available. (Contains 3 figures.)

Kang, Seong-Joo; Ryu, Eun-Hee

2007-01-01

255

Stratospheric nitrogen dioxide in the vicinity of Soufriere, St. Vincent  

SciTech Connect

In April 1979, measurements of nitrogen dioxide in the upper atmosphere were made near Soufriere volcano by twilight optical-absorption techniques. The derived value of 5 x 10/sup +15/ molecules per square centimeter column implies an enhancement of 25 percent over earlier abundances measured in the same latitudinal regions. This enchancement may represent the normal stratospheric variability of nitrogen dioxide in the equatorial region but in any case may be considered an upper limit to the volcano's effect on the total nitrogen dioxide abundance.

Romick, G.J.; Murcray, D.G.; Williams, W.J.

1982-01-01

256

Nuclear magnetic resonance of xenon occluded in Na-A zeolite  

SciTech Connect

Xenon was forced into the ..cap alpha..-cages of a Na-A zeolite at 40 bar and 525 K with up to 1.8 atoms per cage. After cooling to room temperature and releasing pressure, the /sup 129/Xe NMR spectrum taken in air shows five peaks assigned to as many Xe atoms in the cages. Following exposure of the sample to water, the five peaks are replaced by a single one corresponding to a xenon-water clathrate. This work presents an additional application of xenon NMR toward the study of microporosity of solids.

Samant, M.G.; de Menorval, L.C.; Dalla Betta, R.A.; Boudart, M.

1988-06-30

257

Measurement of the quantum efficiency of Hamamatsu R8520 photomultipliers at liquid xenon temperature  

NASA Astrophysics Data System (ADS)

Vacuum ultraviolet light sensitive photomultiplier tubes directly coupled to liquid xenon are being used to efficiently detect the 178 nm scintillation light in a variety of liquid xenon based particle detectors. Good knowledge of the performance of these photomultipliers under cryogenic conditions is needed to properly characterize these detectors. Here, we report on measurements of the quantum efficiency of Hamamatsu R8520 photomultipliers, used in the XENON Dark Matter Experiment. The quantum efficiency measurements at room temperature agree with the values provided by Hamamatsu. At low temperatures, between 160K and 170K, the quantum efficiency increases by ~ 5-11% relative to the room temperature values.

Aprile, E.; Beck, M.; Bokeloh, K.; Budnik, R.; Choi, B.; Contreras, H. A.; Giboni, K.-L.; Goetzke, L. W.; Lang, R. F.; Lim, K. E.; Melgarejo Fernandez, A. J.; Plante, G.; Rizzo, A.; Shagin, P.; Weinheimer, C.

2012-10-01

258

Heterogeneous Nuclear Reactor Models for Optimal Xenon Control.  

NASA Astrophysics Data System (ADS)

Nuclear reactors are generally modeled as homogeneous mixtures of fuel, control, and other materials while in reality they are heterogeneous-homogeneous configurations comprised of fuel and control rods along with other materials. Similarly, for space-time studies of a nuclear reactor, homogeneous, usually one-group diffusion theory, models are used, and the system equations are solved by either nodal or modal expansion approximations. Study of xenon-induced problems has also been carried out using similar models and with the help of dynamic programming or classical calculus of variations or the minimum principle. In this study a thermal nuclear reactor is modeled as a two-dimensional lattice of fuel and control rods placed in an infinite-moderator in plane geometry. The two-group diffusion theory approximation is used for neutron transport. Space -time neutron balance equations are written for two groups and reduced to one space-time algebraic equation by using the two-dimensional Fourier transform. This equation is written at all fuel and control rod locations. Iodine -xenon and promethium-samarium dynamic equations are also written at fuel rod locations only. These equations are then linearized about an equilibrium point which is determined from the steady-state form of the original nonlinear system equations. After studying poisonless criticality, with and without control, and the stability of the open-loop system and after checking its controllability, a performance criterion is defined for the xenon-induced spatial flux oscillation problem in the form of a functional to be minimized. Linear -quadratic optimal control theory is then applied to solve the problem. To perform a variety of different additional useful studies, this formulation has potential for various extensions and variations; for example, different geometry of the problem, with possible extension to three dimensions, heterogeneous -homogeneous formulation to include, for example, homogeneously -distributed burnable poisons, inclusion of additional terms, for example, fast fission and resonance absorption, different fuel and control rod diameters, different distances between rods, different fuel enrichment in different fuel rods, different control concentration in different control rods, and different forms of the performance index, to name a few.

Gondal, Ishtiaq Ahmad

259

Structures of small mixed krypton-xenon clusters.  

PubMed

Structures of small mixed krypton-xenon clusters of different compositions with an average size of 30-37 atoms are investigated. The Kr 3d(5/2) and Xe 4d(5/2) surface core level shifts and photoelectron intensities originating from corner, edge, and face/bulk sites are analyzed by using soft x-ray photoelectron spectroscopy. Structural models are derived from these experiments, which are confirmed by theoretical simulation taking induced dipole interactions into account. It is found that one or two small Xe cores are partly embedded in the surface of the Kr clusters. These may grow and merge leading to a phase separation between the two rare gas moieties in mixed clusters with increasing the Xe content. PMID:22779598

Nagasaka, Masanari; Kosugi, Nobuhiro; Rhl, Eckart

2012-06-21

260

Search for light dark matter in XENON10 data.  

PubMed

We report results of a search for light (?10??GeV) particle dark matter with the XENON10 detector. The event trigger was sensitive to a single electron, with the analysis threshold of 5 electrons corresponding to 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections ?(n)>710(-42)??cm(2), for a dark matter particle mass m(?)=7??GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal. PMID:21867059

Angle, J; Aprile, E; Arneodo, F; Baudis, L; Bernstein, A; Bolozdynya, A I; Coelho, L C C; Dahl, C E; DeViveiros, L; Ferella, A D; Fernandes, L M P; Fiorucci, S; Gaitskell, R J; Giboni, K L; Gomez, R; Hasty, R; Kastens, L; Kwong, J; Lopes, J A M; Madden, N; Manalaysay, A; Manzur, A; McKinsey, D N; Monzani, M E; Ni, K; Oberlack, U; Orboeck, J; Plante, G; Santorelli, R; dos Santos, J M F; Schulte, S; Shagin, P; Shutt, T; Sorensen, P; Winant, C; Yamashita, M

2011-07-27

261

Vapour-liquid equilibrium in the krypton-xenon system  

NASA Astrophysics Data System (ADS)

Isothermal vapour-liquid data were measured for the krypton-xenon system at ten temperatures between 165 and 270 K and pressures to 6.7 MPa, using a vapour recirculating technique. The mixture critical line has been located in (P, T, x) space. Barker's method of data reduction has been used to test the thermodynamic consistency of isotherms below the critical temperature of krypton (209.4 K) and the excess Gibbs energy was evaluated, at the same temperatures, as a function of composition. The results of the experiments have been compared with predictions of the Peng-Robinson equation of state. With interaction parameter calculated by fitting the isotherm of 200.64 K, this equation predicts the liquid and vapour phase compositions to within about a few mole per cent over most of the experimental range.

Calado, Jorge C. G.; Chang, Elaine; Streett, William B.

1983-01-01

262

Avalanche Photodiode for liquid xenon scintillation: quantum efficiency and gain  

NASA Astrophysics Data System (ADS)

We report on measurements with a large area, silicon Avalanche Photodiode (APD) as photodetector for the ultraviolet scintillation light of liquid xenon (LXe) at temperatures between 167 and 188 K. The maximum gain of the APD for the scintillation light from a 210Po ?-source in LXe was 5.3 103. Based on the geometry of the setup, the quantum efficiency of the APD was measured at 34% 5% at the mean scintillation wavelength of 178 nm. The high quantum efficiency and high gain of the APD make it an attractive alternative UV photon sensor to PMTs for LXe detectors, especially for experiments requiring high light yields, such as dark matter searches for Weakly Interacting Massive Particles, or a Compton telescope in MeV ?-ray astronomy.

Shagin, P.; Gomez, R.; Oberlack, U.; Cushman, P.; Sherwood, B.; McClish, M.; Farrell, R.

2009-01-01

263

Power Processing Unit of Xenon Ion Propulsion System  

NASA Astrophysics Data System (ADS)

The structure and optimizing of designing, selecting of parameter was described in this paper, according to the character and desiring of 20cm Xenon ion propulsion system. The Impulse Specific of 20cm XIPS is 3000s,and its thrust is 40mN.The power processing unit (PPU) consists in some modules, they are main hollow cathode heating supply, its igniting one, the contact one, the neutralize heating supply, its igniting one, the contact one, the screen supply, the accelerating supply, and anode supply. Also, the power supply of Xenon storage and feed unit and digital interface and control unit were introduced here. The power supply works with technique of pulse width modulating (PWM) controlled by voltage or current, according to the desiring of the thruster, their stability of output is about 3%. The protecting measure was used as overvoltage, overcurrent and fold back current limiting. For the screen supply, which is higher voltage output, three transformers and three bridges were used to ensure its reliability. The parameter of these modules, showes as following, the igniting supplies outputs1500V/100mA,with protecting of fold back current limiting. The hollow cathode heating supply outputs 0~6V,which is alternate, voltage programmable output and the frequency is 20KHz.The screen is 1000V/0.79A,with stabililizing voltage and protecting of over current output. The anode is 5~7.5A stabililizing current output. The accelerator is -200V/10mA with protecting of over current output. The total power consumptions of PPU are 1100W,and efficient of transfer is more than 80%.

Tiemin, C.

2002-01-01

264

Moving Molecules!  

NSDL National Science Digital Library

In this activity about molecular diffusion (located on page 2 of the PDF), learners will make predictions and move molecules of iodine through a seemingly solid plastic sandwich bag. The process of diffusion will be visually indicated by a color change when the iodine reacts with starch inside the bag. Information in the resource explains how this activity relates to nanoparticles and research. Related to linked video, DragonflyTV Nano: Nanosilver.

Twin Cities Public Television, Inc.

2008-01-01

265

Experimental Investigation of a 12 cm Diameter Kaufman Xenon Ion Thruster.  

National Technical Information Service (NTIS)

An experimental study was performed on discharge performance improvement of an 12 cm diameter Kaufman-type xenon ion thruster to study the effects of discharge chamber configurations on discharge performance. Various discharge chamber configurations were ...

K. Miyazaki Y. Hayakawa S. Kitamura

1991-01-01

266

Ethane and Xenon mixing: density functional theory (DFT) simulations and experiments on Sandia's Z machine  

NASA Astrophysics Data System (ADS)

The combination of ethane and xenon is one of the simplest binary mixtures in which bond breaking is expected to play a role under shock conditions. At cryogenic conditions, xenon is often understood to mix with alkanes such as Ethane as if it were also an alkane, but this model is expected to break down at higher temperatures and pressures. To investigate the breakdown, we have performed density functional theory (DFT) calculations on several xenon/ethane mixtures. Additionally, we have performed shock compression experiments on Xenon-Ethane using the Sandia Z - accelerator. The DFT and experimental results are compared to hydrodynamic simulations using different mixing models in the equation of state. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of the Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Magyar, Rudolph; Root, Seth; Mattsson, Thomas; Cochrane, Kyle

2012-02-01

267

Experimental studies of a zeeman-tuned xenon laser differential absorption apparatus.  

PubMed

A Zeeman-tuned cw xenon laser differential absorption device is described. The xenon laser was tuned by axial magnetic fields up to 5500 G generated by an unusually large water-cooled dc solenoid. Xenon laser lines at 3.37 micro, 3.51 micro, and 3.99 micro were tuned over ranges of 6 A, 6 A, and 11 A, respectively. To date, this apparatus has been used principally to study the details of formaldehyde absorption lines lying near the 3 .508-micro xenon laser transition. These experiments revealed that the observed absorption spectrum of formaldehyde exhibits a sufficiently unique spectral structure that the present technique may readily be used to measure relative concentrations of formaldehyde in samples of polluted air. PMID:20125492

Linford, G J

1973-06-01

268

NASA's Evolutionary Xenon Thruster (NEXT) Power Processing Unit (PPU) Capacitor Failure Root Cause Analysis.  

National Technical Information Service (NTIS)

The NASA's Evolutionary Xenon Thruster (NEXT) project is developing an advanced ion propulsion system for future NASA missions for solar system exploration. A critical element of the propulsion system is the Power Processing Unit (PPU) which supplies regu...

A. J. Birchenough J. F. Soeder J. W. Dunning L. R. Pinero R. J. Scheidegger

2012-01-01

269

Digital Imaging with a Pressurized Xenon Filled MWPC Working at a High Data Rate.  

National Technical Information Service (NTIS)

A multiwire proportional chamber based detection system for medical imaging is presented. The system consists of a pressurized xenon filled MWPC and of a monochromatic fluorescent, X-ray source using a conventional diagnostic tube with various target filt...

R. Bellazzini A. Brez A. Del Guerra M. M. Massai M. R. Torquati

1984-01-01

270

State Parameters of Pulse-Discharge Plasma in Xenon-Filled Closed Tube (Abstract Only).  

National Technical Information Service (NTIS)

In a diagnostic study of pulse-discharge plasma in xenon flash tubes, the state parameters of such a plasma were measured in an experiment by spectroscopic methods. The plasma temperature was determined from the spectral density, brightness, and absorptiv...

V. Y. Gavrilov

1987-01-01

271

Xenon Difluoride Fluorination. Mechanism and Selectivity of Boron Trifluoride Etherate Catalysis in the Norbornene Model.  

National Technical Information Service (NTIS)

The boron trifluoride etherate initiated fluorination of norbornene with xenon difluoride in dichloromethane solvent selectively produces the novel 2-exo-5-exo-difluoronorbornane and its analogous 2-endo 5-exo-difluoronorbornane represent approximately ha...

S. A. Shackelford

1978-01-01

272

Cerebral blood flow response to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in children  

SciTech Connect

We examined the relationship of changes in partial pressure of carbon dioxide on cerebral blood flow responsiveness in 20 pediatric patients undergoing hypothermic cardiopulmonary bypass. Cerebral blood flow was measured during steady-state hypothermic cardiopulmonary bypass with the use of xenon 133 clearance methodology at two different arterial carbon dioxide tensions. During these measurements there was no significant change in mean arterial pressure, nasopharyngeal temperature, pump flow rate, or hematocrit value. Cerebral blood flow was found to be significantly greater at higher arterial carbon dioxide tensions (p less than 0.01), so that for every millimeter of mercury rise in arterial carbon dioxide tension there was a 1.2 ml.100 gm-1.min-1 increase in cerebral blood flow. Two factors, deep hypothermia (18 degrees to 22 degrees C) and reduced age (less than 1 year), diminished the effect carbon dioxide had on cerebral blood flow responsiveness but did not eliminate it. We conclude that cerebral blood flow remains responsive to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in infants and children; that is, increasing arterial carbon dioxide tension will independently increase cerebral blood flow.

Kern, F.H.; Ungerleider, R.M.; Quill, T.J.; Baldwin, B.; White, W.D.; Reves, J.G.; Greeley, W.J. (Duke Univ. Medical Center, Durham, NC (USA))

1991-04-01

273

Process for producing manganese dioxide  

SciTech Connect

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to yield high density manganese dioxide. The manganese dioxide formed in the process can be deposited directly onto the surface of electrolytic manganese dioxide (EMD). The manganese dioxide product the is particularly suitable for use as a cathode active material in electrochemical cells. 16 figs.

Wang, E.I.; Lin, L.; Bowden, W.L.

1994-01-11

274

SAUNAa system for automatic sampling, processing, and analysis of radioactive xenon  

Microsoft Academic Search

A system for automatic sampling, processing, and analysis of atmospheric radioxenon has been developed. From an air sample of about 7m3 collected during 12h, 0.5cm3 of xenon is extracted, and the atmospheric activities from the four xenon isotopes 133Xe, 135Xe, 131mXe, and 133mXe are determined with a betagamma coincidence technique. The collection is performed using activated charcoal and molecular sieves

A. Ringbom; T. Larson; A. Axelsson; K. Elmgren; C. Johansson

2003-01-01

275

High-power short-pulse xenon dimer spontaneous radiation source  

SciTech Connect

A high-power VUV radiation source based on a self-sustained nanosecond volume discharge in an inhomogeneous electric field is developed. It is shown that the volume discharge can be formed at high xenon and helium pressures without using a preionisation source. The 8-ns (FWHM), 172-nm, 1-MW radiation pulses emitted into a total solid angle are obtained in xenon at a pressure of 12 atm. (vuv radiation sources)

Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F; Baksht, E Kh [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation); Mesyats, Gennadii A [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2007-06-30

276

Imaging local cerebral blood flow by Xenon-enhanced computed tomography Technical optimization procedures  

Microsoft Academic Search

Methods are described for non-invasive, computer-assisted serial scanning throghout the human brain during eight minutes of inhalation of 27%30% Xenon gas in order to measure local cerebral blood flow (LCBF). Optimized Xenonenhanced computed tomography (XeCT) was achieved by 5-second scanning at one-minute intervals utilizing a state-of-the-art CT scanner and rapid delivery of Xenon gas via a face mask. Values for

J. S. Meyer; T. Shinohara; A. Imai; M. Kobari; F. Sakai; T. Hata; W. T. Oravez; G. M. Timpe; T. Deville; E. Solomon

1988-01-01

277

Enhancement of Solution NMR and MRI with Laser-Polarized Xenon  

Microsoft Academic Search

Optical pumping with laser light can be used to polarize the nuclear spins of gaseous xenon-129. When hyperpolarized xenon-129 is dissolved in liquids, a time-dependent departure of the proton spin polarization from its thermal equilibrium is observed. The variation of the magnetization is an unexpected manifestation of the nuclear Overhauser effect, a consequence of cross-relaxation between the spins of solution

G. Navon; Y.-Q. Song; S. Appelt; R. E. Taylor; A. Pines

1996-01-01

278

Xenon offers stable haemodynamics after global hypoxic-ischaemia in newborn pigs  

Microsoft Academic Search

BackgroundPerinatal hypoxic ischaemic encephalopathy (HIE) causes cardiac dysfunction\\/hypotension. Xenon (Xe) anaesthesia offers short term stable haemodynamics in human adults\\/mature animals with cardiovascular risk. We studied long term haemodynamics during 50% xenon inhalation at normothermia (NT 38.5C) or hypothermia (HT 33.5C) in a newborn global Hypoxic-Ischaemic (HI) pig model.Methods98 newborn pigs were ventilated under inhalational anaesthesia, given a 45 min global

E Chakkarapani; X Liu; J Dingley; M Thoresen

2011-01-01

279

Revised and Extended Analysis of Six Times Ionized Xenon: Xe VII  

Microsoft Academic Search

The spectra of xenon were recorded in the 100-1250 region on a variety of vacuum spectrographs at the Antigonish, NIST and Troitsk laboratories. The source used at the Antigonish and the NIST laboratories was a xenon-gas-puff low inductance vacuum spark while at the Troitsk laboratory it was a 40 kV fast capillary discharge. On the basis of our new

S. S. Churilov; Y. N. Joshi

2002-01-01

280

Global characteristics of an ATON stationary plasma thruster operating with krypton and xenon  

Microsoft Academic Search

The global characteristics of an ATON stationary plasma thruster operating on xenon and krypton are investigated. It is shown\\u000a that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower\\u000a than those with xenon. An efficiency of ?60% was achieved with krypton for the specific impulse attaining 3000

A. I. Bugrova; A. S. Lipatov; A. I. Morozov; L. V. Solomatina

2002-01-01

281

Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind  

Microsoft Academic Search

Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

R. O. Pepin; R. H. Becker; P. E. Rider

1995-01-01

282

A study of the scintillation light induced in liquid xenon by electrons and alpha particles  

Microsoft Academic Search

The time dependence and the intensity of the primary scintillation light in liquid xenon excited by 241Am alpha particles and 207Bi internal conversion electrons were measured at different electric field strengths. High-purity liquid xenon was used to fill a parallel-plate ionization chamber equipped with a CaF2 window coupled to a UV (ultraviolet) sensitive photomultiplier tube. The effect of the specific

Elena Aprile; Reshmi Mukherjee; Masayo Suzuki

1990-01-01

283

Liquid xenon gamma-ray imaging telescope (LXeGRIT) for medium energy astrophysics  

Microsoft Academic Search

As part of our ongoing research program to develop a liquid xenon gamma-ray imaging telescope (LXe-GRIT) for medium energy astrophysics, we have built a liquid xenon time projection chamber (LXeTPC) with a total volume of 10 liters and a sensitive are of 20 cm by 20 cm. The detector has been successfully tested with gamma-ray sources in the laboratory and

Elena Aprile; Valeri Egorov; Fang Xu; Edward L. Chupp; Philip Dunphy; Tadayoshi Doke; Jun Kikuchi; Gerald J. Fishman; Geoffrey N. Pendleton; Kimiaki Masuda; Toshisuke Kashiwagi

1996-01-01

284

Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters  

NASA Astrophysics Data System (ADS)

Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the average ionization and the thermodynamic regimes of xenon plasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blast waves launched in xenon clusters.

Rodriguez, R.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

2011-06-01

285

AgClXe Silver chloride - xenon (1/1)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume B 'Linear Polyatomic Molecules' of Volume 29 'Molecular Constants Mostly from Microwave, Molecular Beam, and Sub-Doppler Laser Spectroscopy' of Landolt-Brnstein - Group II 'Molecules and Radicals'.

Wlodarczak, G.

286

Carbon dioxide (reduction).  

National Technical Information Service (NTIS)

The twin problems of global warming, caused by an increase in atmospheric carbon dioxide (CO2) concentrations, and limited fossil fuel resources have stimulated research in the utilization of CO2. These problems would be partially alleviated by the develo...

A. Fujita

2000-01-01

287

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The collection of luminescent microorganisms are maintained under cultivation to provide suitable biosensors for the testing program for carbon dioxide. The basic bioluminescent agar medium is currently being used for growth of the cultures. Tests of lumi...

P. S. Biernacki J. J. Kalvinskas

1973-01-01

288

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The program was initiated to establish the feasibility of applying bioluminescent technology for monitoring of carbon dioxide (CO2) in life-support systems for divers, swimmers and underwater habitats. Experiments were performed to obtain bioluminescent c...

P. S. Biernacki J. J. Kalvinskas

1973-01-01

289

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The program was initiated to establish the feasibility of applying bioluminescent technology for monitoring of carbon dioxide (CO2) in life-support systems for divers, swimmers and underwater habitats. Experiments were performed to obtain bioluminescent c...

P. S. Biernacki J. L. Kalvinskas

1974-01-01

290

Carbon Dioxide Absorption Manifold.  

National Technical Information Service (NTIS)

The device is for removing carbon dioxide from the atmosphere without the attendant release or production of noxious chemicals. It is for use in a submerged submarine. The device includes a housing, inlets, canisters containing lithium hydroxide, a blower...

W. E. McConnaughey

1965-01-01

291

Walking molecules.  

PubMed

Movement is intrinsic to life. Biologists have established that most forms of directed nanoscopic, microscopic and, ultimately, macroscopic movements are powered by molecular motors from the dynein, myosin and kinesin superfamilies. These motor proteins literally walk, step by step, along polymeric filaments, carrying out essential tasks such as organelle transport. In the last few years biological molecular walkers have inspired the development of artificial systems that mimic aspects of their dynamics. Several DNA-based molecular walkers have been synthesised and shown to walk directionally along a track upon sequential addition of appropriate chemical fuels. In other studies, autonomous operation--i.e. DNA-walker migration that continues as long as a complex DNA fuel is present--has been demonstrated and sophisticated tasks performed, such as moving gold nanoparticles from place-to-place and assistance in sequential chemical synthesis. Small-molecule systems, an order of magnitude smaller in each dimension and 1000 smaller in molecular weight than biological motor proteins or the walker systems constructed from DNA, have also been designed and operated such that molecular fragments can be progressively transported directionally along short molecular tracks. The small-molecule systems can be powered by light or chemical fuels. In this critical review the biological motor proteins from the kinesin, myosin and dynein families are analysed as systems from which the designers of synthetic systems can learn, ratchet concepts for transporting Brownian substrates are discussed as the mechanisms by which molecular motors need to operate, and the progress made with synthetic DNA and small-molecule walker systems reviewed (142 references). PMID:21416072

von Delius, Max; Leigh, David A

2011-03-17

292

Multiphoton ionization and third-harmonic generation in atoms and molecules  

SciTech Connect

We will discuss recent experiments on multiphoton ionization and third-harmonic generation in rare gases and small molecules using focused laser power densities of 10/sup 9/ to 10/sup 11/ W/cm/sup 2/. Also, some elementary experiments using vacuum ultraviolet light generated by frequency tripling in xenon and krypton will be described. These experiments include absorption and ionization studies using vacuum ultraviolet radiation as well as two-photon ionization using one vacuum ultraviolet photon and one laser photon.

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

1982-01-01

293

[Minimal-flow xenon and semiclosed circuit anesthesia for computed tomographic measurement of local cerebral blood flow (LCBF)].  

PubMed

For the purpose of decreasing the volume of expensive xenon, anesthesia with minimal-flow xenon and semiclosed circuit were induced for computed tomographic LCBF measurement. Eighteen patients with ischemic cerebral disease were studied. Anesthesia was induced with minimum dose of thiopental, diazepam and fentanyl. Muscle relaxation was obtained by means of pancuronium bromide. Patients were intubated and ventilated mechanically with flows of 6 l/min. O2 for 20 to 30 minutes to eliminate nitrogen from the system. O2 concentrations in semiclosed circuit were monitored throughout the procedures using galvanic battery. Endtidal CO2 tension was also measured for maintaining normocarbia. Blood gas analyses were carried out before xenon inhalation, during xenon inhalation and immediately before stopping inhalation of xenon-oxygen mixture. Xenon inhalation programs were subdivided into three groups, each of them consisted of 6 patients. The formula for calculating fresh gas flow for low flow semiclosed circuit was introduced according to Shimoji's which was based on the original formula of Foldes. O2 concentration in circuit was predicted to be 25%. Mean xenon uptake for initial 20 minutes was predicted to be 125 ml/min. or 360 ml/min. (Formula: see text) (CRO2: O2% in semiclosed circuit. FO2: fresh O2 flow ml/min. FXe: fresh xenon flow ml/min. VO2: oxygen consumption ml/min. VXe: mean xenon uptake ml/min.) The first group started xenon inhalation during pure xenon inflow into semiclosed circuit for two minutes and followed by about 68% xenon in O2 inhalation for 23 minutes. FXe and VXe were fixed at 700 ml/min and 360 ml/min respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6498027

Oku, S; Karasawa, J; Kuriyama, Y; Satou, K; Yahagi, N; Okumura, F; Kikuchi, H; Sawada, T; Sakashita, Z; Naitou, H

1984-08-01

294

Fast oscillatory behavior of the excited xenon density in the discharge cells of a plasma display panel  

SciTech Connect

Fast oscillation of the excited xenon density occurs universally after an electrical discharge in the cells of a plasma display panel. A theoretical model based on ion plasma oscillation simulates this oscillatory behavior of the excited xenon density reasonably well. The magnitude and lifetime of the excited xenon density in a metastable state depend highly on the electrode configuration. Particularly, T-type electrodes provide better generation and confinement of excited xenon atoms for an abundant emission of 173 nm ultraviolet light at a high level of efficiency.

Uhm, Han S. [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of); Choi, Eun H. [Department of Electrophysics, PDP Research Center, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2009-03-15

295

Photolysis and xenon flash pyrolysis of coal-derived wastes  

Microsoft Academic Search

We wish to report that one can irradiate coal gasification condensate waters under basic conditions using a platinized titanium dioxide photocatalyst and visible or ultraviolet light to give H and CO as the only two gases. Irradiation with solar energy also shows an initial decrease in total organic carbon of approximately twenty percent. In our investigations, biosludge obtained from the

Worman

1986-01-01

296

Compressed xenon gas near its critical point as an ionization medium  

SciTech Connect

As part of an effort to study Ov [beta][beta] decay of [sup 136]Xe, a compressed xenon drift chamber has been developed. In such a chamber, the ability to drift ionization over large distances without attenuation, stability with time, and excellent energy resolution are essential. Xenon is an attractive candidate for use as an ionization detection medium. Its low cost in large volumes gives it an advantage over solid-state detectors. Its large atomic number (Z = 54) and density (when compressed or condensed) give a high stopping power for [gamma]-radiation. The low average energy required to produce an electron-ion pair and small Fano factor allow good energy resolution. The expected intrinsic energy resolution is 2 and 4 keV FWHM at 1 MeV in liquid and gaseous xenon, respectively. Thus, high density xenon spectrometers have a detection efficiency similar to NaI(T1) crystals of the same size and an energy resolution comparable in theory to that in Ge(Li) detectors. However, the best energy resolution results in liquid xenon, 34 and 54 keV FWHM for the 570 and 1,064 keV photo-peaks of [sup 207]Bi, respectively, fall considerably short of the Fano factor predictions. It appears that the resolution is limited by some process other than Poisson fluctuations. In this report the authors describe results obtained from a dual gridded ionization chamber filled with highly purified gaseous xenon operating near its critical point where the density, [rho][sub c] = 1.09 g/cm[sup 3], approaches that of the liquid phase. This thermodynamic regime has not previously been studied in xenon.

Levin, C.; Markey, J. (Yale Univ., New Haven, CT (United States). A.W. Wright Nuclear Structure Lab.)

1993-08-01

297

Carbon dioxide poisoning.  

PubMed

Carbon dioxide is a physiologically important gas, produced by the body as a result of cellular metabolism. It is widely used in the food industry in the carbonation of beverages, in fire extinguishers as an 'inerting' agent and in the chemical industry. Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death. Solid carbon dioxide may cause burns following direct contact. If it is warmed rapidly, large amounts of carbon dioxide are generated, which can be dangerous, particularly within confined areas. The management of carbon dioxide poisoning requires the immediate removal of the casualty from the toxic environment, the administration of oxygen and appropriate supportive care. In severe cases, assisted ventilation may be required. Dry ice burns are treated similarly to other cryogenic burns, requiring thawing of the tissue and suitable analgesia. Healing may be delayed and surgical intervention may be required in severe cases. PMID:16499405

Langford, Nigel J

2005-01-01

298

Human Regional Pulmonary Gas Exchange with Xenon Polarization Transfer (XTC)  

NASA Astrophysics Data System (ADS)

Xenon Transfer Contrast (XTC) is an existing imaging method (Ruppert et al, Magn Reson Med, 51:676-687, 2004) that measures the fraction F of ^129Xe magnetization that diffuses from alveolar gas spaces to septal parenchymal tissue in lungs in a specified exchange time. As previously implemented, XTC is a 2-breath method and has been demonstrated in anesthetized animals. To use XTC in humans and to avoid issues associated with obtaining identical gas volumes on subsequent breath-hold experiments as well as precise image registration in post-processing, a single breath XTC method was developed that acquires three consecutive gradient echo images in an 8s acquisition. We report here initial measurements of the mean and variance of F for 5 normal healthy subjects as well as 7 asymptomatic smokers. The experiments were performed at two lung volumes (45 and 65% of TLC). We found that both the mean and variance of F increased with smoking history. In comparison, standard pulmonary function tests such as DLCO FEV1 showed no correlation with smoking history.

Muradian, Iga; Butler, James; Hrovat, Mirko; Topulos, George; Hersman, Elizabeth; Ruset, Iulian; Covrig, Silviu; Frederick, Eric; Ketel, Stephen; Hersman, F. W.; Patz, Samuel

2007-03-01

299

FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF  

SciTech Connect

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 {+-} 0.5 and log Xe = -4.2 {+-} 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

Werner, Klaus; Rauch, Thomas; Ringat, Ellen [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University Tuebingen, Sand 1, 72076 Tuebingen (Germany); Kruk, Jeffrey W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-07-01

300

First Detection of Krypton and Xenon in a White Dwarf  

NASA Astrophysics Data System (ADS)

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 0.5 and log Xe = -4.2 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

2012-07-01

301

Spin relaxation in hyperpolarized krypton-83 and xenon-129  

NASA Astrophysics Data System (ADS)

The potential medical application of hyperpolarized (hp) krypton-83 (spin S = 9/2) [1] make a better insight into the NMR relaxation behavior of this isotope desirable, in particular since the relaxation limits the observed signal intensity but also provides a source for MRI contrast. The quadrupolar relaxation of krypton-83 is shown to be highly dependent on temperature, optical pumping gas mixture, the nature of surrounding surfaces and the applied magnetic field strength [2, 3]. The relaxation is mainly caused by quadrupolar interactions during brief surface adsorption periods of the krypton atoms onto the surrounding container walls. In contrast to xenon-129, interactions with paramagnetic impurities in the surface or with gas phase oxygen are not significant. 1) Pavlovskaya, et al. Proc. Natl. Acad. Sci. U.S.A.,2005. 102: 18275-18279; 2) Cleveland, Z.I., et al. J. Chem. Phys., 2006. 124(4) 044311; 3) Stupic, K.F et al. Solid State Nucl. Magn. Reson., 2006. 29: 79-84.

Meersmann, Thomas; Cleveland, Zackary; Stupic, Karl; Pavlovskaya, Galina

2007-03-01

302

Collectivity in the light xenon isotopes: A shell model study  

NASA Astrophysics Data System (ADS)

The lightest xenon isotopes are studied in the shell model framework, within a valence space that comprises all the orbits lying between the magic closures N=Z=50 and N=Z=82. The calculations produce collective deformed structures of triaxial nature that encompass nicely the known experimental data. Predictions are made for the (still unknown) N=Z nucleus Xe108. The results are interpreted in terms of the competition between the quadrupole correlations enhanced by the pseudo-SU(3) structure of the positive parity orbits and the pairing correlations brought in by the 0h11/2 orbit. We also have studied the effect of the excitations from the Sn100 core on our predictions. We show that the backbending in this region is due to the alignment of two particles in the 0h11/2 orbit. In the N=Z case, one neutron and one proton align to J=11 and T=0. In Xe110,112 the alignment begins in the J=10, T=1 channel and it is dominantly of neutron-neutron type. Approaching the band termination the alignment of a neutron-proton pair to J=11 and T=0 takes over. In a more academic mood, we have studied the role of the isovector and isoscalar pairing correlations on the structure on the yrast bands of Xe108,110 and examined the possible existence of isovector and isoscalar pairing condensates in these N~Z nuclei.

Caurier, E.; Nowacki, F.; Poves, A.; Sieja, K.

2010-12-01

303

Mind molecules.  

PubMed

Scientific styles vary tremendously. For me, research is largely about the unfettered pursuit of novel ideas and experiments that can test multiple ideas in a day, not a year, an approach that I learned from my mentor Julius "Julie" Axelrod. This focus on creative conceptualizations has been my mtier since working in the summers during medical school at the National Institutes of Health, during my two years in the Axelrod laboratory, and throughout my forty-five years at Johns Hopkins University School of Medicine. Equally important has been the "high" that emerges from brainstorming with my students. Nothing can compare with the eureka moments when, together, we sense new insights and, better yet, when high-risk, high-payoff experiments succeed. Although I have studied many different questions over the years, a common theme emerges: simple biochemical approaches to understanding molecular messengers, usually small molecules. Equally important has been identifying, purifying, and cloning the messengers' relevant biosynthetic, degradative, or target proteins, at all times seeking potential therapeutic relevance in the form of drugs. In the interests of brevity, this Reflections article is highly selective, and, with a few exceptions, literature citations are only of findings of our laboratory that illustrate notable themes. PMID:21543333

Snyder, Solomon H

2011-05-04

304

Mind Molecules  

PubMed Central

Scientific styles vary tremendously. For me, research is largely about the unfettered pursuit of novel ideas and experiments that can test multiple ideas in a day, not a year, an approach that I learned from my mentor Julius Julie Axelrod. This focus on creative conceptualizations has been my mtier since working in the summers during medical school at the National Institutes of Health, during my two years in the Axelrod laboratory, and throughout my forty-five years at Johns Hopkins University School of Medicine. Equally important has been the high that emerges from brainstorming with my students. Nothing can compare with the eureka moments when, together, we sense new insights and, better yet, when high-risk, high-payoff experiments succeed. Although I have studied many different questions over the years, a common theme emerges: simple biochemical approaches to understanding molecular messengers, usually small molecules. Equally important has been identifying, purifying, and cloning the messengers' relevant biosynthetic, degradative, or target proteins, at all times seeking potential therapeutic relevance in the form of drugs. In the interests of brevity, this Reflections article is highly selective, and, with a few exceptions, literature citations are only of findings of our laboratory that illustrate notable themes.

Snyder, Solomon H.

2011-01-01

305

Carbon dioxide as a feedstock.  

National Technical Information Service (NTIS)

This report is an overview on the subject of carbon dioxide as a starting material for organic syntheses of potential commercial interest and the utilization of carbon dioxide as a substrate for fuel production. It draws extensively on literature sources,...

Creutz Fujita

2000-01-01

306

Characterization of a liquid-xenon-jet laser-plasma extreme-ultraviolet source  

NASA Astrophysics Data System (ADS)

A liquid-xenon-jet laser-plasma source for extreme-ultraviolet (EUV) and soft-x-ray generation has been characterized. Being a source candidate for EUV lithography (EUVL), we especially focus on parameters important for the integration of the source in EUVL systems. The deep-ultraviolet (DUV) out-of-band radiation (?=120-400 nm) was quantified, to within a factor of two, using a flying-circus tool together with a transmission-grating spectrograph resulting in a total DUV conversion efficiency (CE) of ~0.33%/2?sr. The size and the shape of the xenon plasma was investigated using an in-band-only EUV microscope, based on a spherical Mo/Si multilayer mirror and a charge-coupled device detector. Scalability of the source size from 20-270 ?m full width at half maximum was shown. The maximum repetition-rate sustainable by the liquid-xenon-jet target was simulated by a double-pulse experiment indicating feasibility of >17 kHz operation. The xenon-ion energy distribution from the plasma was determined in a time-of-flight experiment with a Faraday-cup detector showing the presence of multi-kilo-electron-volt ions. Sputtering of silicon witness plates exposed to the plasma was observed, while a xenon background of >1 mbar was shown to eliminate the sputtering. It is concluded that the source has potential to meet the requirements of future EUVL systems.

Hansson, B. A. M.; Hemberg, O.; Hertz, H. M.; Berglund, M.; Choi, H.-J.; Jacobsson, B.; Janin, E.; Mosesson, S.; Rymell, L.; Thoresen, J.; Wilner, M.

2004-06-01

307

Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant  

SciTech Connect

For krypton to become a realistic option for Hall thruster operation, it is necessary to understand the performance gap between xenon and krypton and what can be done to reduce it. A floating emissive probe is used with the Plasmadynamics and Electric Propulsion Laboratory's High-speed Axial Reciprocating Probe system to map the internal plasma potential structure of the NASA-173Mv1 Hall thruster [R. R. Hofer, R. S. Jankovsky, and A. D. Gallimore, J. Propulsion Power 22, 721 (2006); and ibid.22, 732 (2006)] using xenon and krypton propellant. Measurements are taken for both propellants at discharge voltages of 500 and 600 V. Electron temperatures and electric fields are also reported. The acceleration zone and equipotential lines are found to be strongly linked to the magnetic-field lines. The electrostatic plasma lens of the NASA-173Mv1 Hall thruster strongly focuses the xenon ions toward the center of the discharge channel, whereas the krypton ions are defocused. Krypton is also found to have a longer acceleration zone than the xenon cases. These results explain the large beam divergence observed with krypton operation. Krypton and xenon have similar maximum electron temperatures and similar lengths of the high electron temperature zone, although the high electron temperature zone is located farther downstream in the krypton case.

Linnell, Jesse A.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, Department of Aerospace Engineering, University of Michigan, 1919 Green Road B107, Ann Arbor, Michigan 48109 (United States)

2006-09-15

308

Modeling Double Hole Dynamics in Intense Laser Produced Xenon Cluster Plasmas  

NASA Astrophysics Data System (ADS)

When femtosecond laser pulses with intensities greater than 10^19W/cm^2 interact with a cluster of xenon atoms, the atoms are stripped of their N-shell electrons in less than a femtosecond and a Coulomb explosion ensues with ions initially in the ground state of Ni-like xenon. X-ray lasing at 2.86 has been observed in such cluster explosions [1] and gain coefficients were measured. Gains comparable to those measured have been obtained in the single hole states of Co-like xenon in an initial non-equilibrium theoretical analysis of these experiments [2]. Alternatively, x-ray amplification has also been attributed to the generation of population inversions between double and single hole states in the M-shell ions of xenon [3]. In order to investigate the viability of this possibility, we have added double hole states to the Fe-like ionization stage of our detailed ionization dynamic model of Ni-, Co-, and Fe-like xenon [2]. Results from our model calculations will be presented in this talk. [0pt] [1] A. B. Borisov, et. al., J. Phys. B: At. Mol. Opt. Phys. 40 (2007) F307. [2] Tz. B. Petrova, et. al., J. Phys. B: At. Mol. Opt. Phys. 43 (2010) 025601. [3] W. Andreas Schroeder, et. al., J. Phys. B: At. Mol. Opt. Phys. 34 (2001) 297.

Petrova, Tzvetelina; Whitney, Kenneth; Davis, Jack; Petrov, George

2010-11-01

309

Xenon porometry: a novel method for the derivation of pore size distributions.  

PubMed

Xenon porometry is a novel method used for characterizing porous materials by the (129)Xe nuclear magnetic resonance of xenon gas. With the method, the diffusion of gas is slowed down by immersing the material in a medium, which can be in liquid or solid state during measurements. Because of slow diffusion, the signal of a xenon atom is characteristic of the properties of only one pore, and the composite signal of all atoms represents the distribution of properties. The method is especially applicable for determining pore size distribution because the chemical shifts of two different xenon signals (one from liquid and the other from gas pockets in solid) are dependent on pore size. Therefore, the shapes of these signals represent pore size distribution function. In addition, the porosity of the material can be determined by comparing the intensities of two signals. This article focuses on describing xenon signals observed from gas pockets in a solid medium, which has turned out to be most convenient for pore size determination. PMID:17466763

Telkki, Ville-Veikko; Lounila, Juhani; Jokisaari, Jukka

2007-01-16

310

Detection of residual krypton in xenon gas for WIMP dark matter searches  

NASA Astrophysics Data System (ADS)

The next generation of WIMP dark matter searches using liquid xenon as a target medium will require unprecedented rejection of residual krypton contamination. Krypton contains the beta emitting isotope ^85Kr, with a relative abundance of about 10-11 (^85Kr/^natKr), and this beta decay can be an important source of background for these experiments. Krypton is typically present in commercially produced xenon at the level of tens of parts-per-billion, about four orders of magnitude too large for present day dark matter experiments such as XENON, LUX, and XMASS. Additional processing via gas chromatography and distillation are used to separate krypton from xenon, but measuring the remaining krypton level at the part-per-trillion (ppt) level is challenging. Recently we have developed a highly sensitive and simple technique to measure residual krypton contamination in xenon gas using an RGA mass spectrometer and a liquid nitrogen cold trap. We describe here the results of our calibration experiments to determine the ultimate limit of detection of the method, and we discuss the implications for the next generation of WIMP dark matter experiments.

Dobi, Attila

2011-04-01

311

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects  

SciTech Connect

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ninety-four of these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Three segmental perfusion defects were noted in association with isolated xenon retention. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects.

Bushnell, D.L.; Sood, K.B.; Shirazi, P.; Pal, I. (VA Hines Hospital, IL (USA))

1990-08-01

312

Modeling the Removal of Xenon from Lithium Hydrate with Aspen HYSYS  

NASA Astrophysics Data System (ADS)

The Laser Inertial Fusion Engine (LIFE) project mission is to provide a long-term, carbon-free source of sustainable energy, in the form of electricity. A conceptual xenon removal system has been modeled with the aid of Aspen HYSYS, a chemical process simulator. Aspen HYSYS provides excellent capability to model chemical flow processes, which generates outputs which includes specific variables such as temperature, pressure, and molar flow. The system is designed to strip out hydrogen isotopes deuterium and tritium. The base design bubbles plasma exhaust laden with x filled with liquid helium. The system separates the xenon from the hydrogen, deuterium, and tritium with a lithium hydrate and a lithium bubbler. After the removal of the hydrogen and its isotopes, the xenon is then purified by way of the process of cryogenic distillation. The pure hydrogen, deuterium, and tritium are then sent to the isotope separation system (ISS). The removal of xenon is an integral part of the laser inertial fusion engine and Aspen HYSYS is an excellent tool to calculate how to create pure xenon.

Efthimion, Phillip; Gentile, Charles

2011-11-01

313

Instrumentation for the breath-by-breath determination of oxygen and carbon dioxide based on nondispersive absorption measurements.  

PubMed

This paper describes the development and evaluation of instrumentation for the breath-by-breath determination of oxygen and carbon dioxide in respiratory gases. The method is based on nondispersive absorption and uses the 145-nm absorption band for detection of oxygen and the 4.3-micron band for detection of carbon dioxide. A xenon discharge lamp with a sharp band at 147 nm was chosen as the source for the determination of oxygen, and a carbon dioxide discharge lamp with a sharp band at 4.3 micron was chosen for determination of carbon dioxide. A vacuum photodiode was used as the detector for oxygen, and a photoconductive cell with a built-in interference filter was used for detection of carbon dioxide. Plots of absorbance (A) vs concentration (C, %) were linear for oxygen and were nonlinear for carbon dioxide. Typical least-squares calibration equations were A = 0.020C + 0.02 for oxygen (0-100%) and A = 0.0012C2 + 0.050C + 0.008 for carbon dioxide (0-8%). Comparisons of computed (y) vs prepared (x) values for the concentrations given above were linear for both gases, yielding y = (1.00 +/- 0.01)x - 0.13 +/- 0.73 for oxygen and y = (1.07 +/- 0.02)x - 0.04 +/- 0.06 for carbon dioxide. The standard deviations were 1.2% at 50% oxygen and 1.5% at 4% carbon dioxide. Records are presented to illustrate breath-by-breath monitoring of these gases in a healthy subject. PMID:1616125

Arnoudse, P B; Pardue, H L; Bourland, J D; Miller, R; Geddes, L A

1992-01-15

314

PERSONAL MONITOR FOR NITROGEN DIOXIDE  

EPA Science Inventory

An attempt was made to develop a personal monitor to measure nitrogen dioxide. Sampling of nitrogen dioxide is accomplished by permeation through a silicone membrane into a alkaline thymol blue solution. The nitrogen dioxide is converted to nitrite and is then quantitated by colo...

315

Carbon dioxide absorption methanol process  

Microsoft Academic Search

A process is described for removing carbon dioxide from a feed stream of natural gas, having at least methane, ethane and heavier hydrocarbon, comprising: separating the feed stream in a first separator to form a first stream, having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane, and a second stream, having methane, carbon dioxide and

Apffel

1987-01-01

316

Process for producing manganese dioxide  

Microsoft Academic Search

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to

E. I. Wang; L. Lin; W. L. Bowden

1994-01-01

317

Light amplification at a wavelength of 172 nm in atmospheric-pressure xenon excited by a high-power proton beam  

NASA Astrophysics Data System (ADS)

An amplification effect at a xenon dimer transition (wavelength 172 nm) was observed during the excitation of atmospheric-pressure xenon by a 500-keV, 200-A/sq cm proton beam. A maximum gain coefficient of 6/m was observed at a xenon pressure of 3 atm and a pump power density of 50 MW/cu cm.

Kuznetsov, A. A.; Sulakshin, S. S.

1990-02-01

318

Facile xenon capture and release at room temperature using a metal-organic framework: a comparison with activated charcoal  

SciTech Connect

Two well known Metal organic frameworks (MOF-5, NiDOBDC) were synthesized and studied for facile xenon capture and separation. Our results indicate the NiDOBDC adsorbs significantly more xenon than MOF-5, releases it more readily than activated carbon, and is more selective for Xe over Kr than activated carbon.

Thallapally, Praveen K.; Grate, Jay W.; Motkuri, Radha K.

2012-01-11

319

Radioactive Plume from the Three Mile Island Accident: Xenon133 in Air at a Distance of 375 Kilometers  

Microsoft Academic Search

The transit of an air mass containing radioactive gas released from the Three Mile Island reactor was recorded in Albany, New York, by measuring xenon-133. These measurements provide an evaluation of Three Mile Island effluents to distances greater than 100 kilometers. Two independent techniques identified xenon-133 in ambient air at concentrations as high as 3900 picocuries per cubic meter. The

Martin Wahlen; Charles O. Kunz; John M. Matuszek; William E. Mahoney; Roger C. Thompson

1980-01-01

320

Production of H - ions with addition of cesium or xenon to a hydrogen discharge in a small multicusp ion source  

Microsoft Academic Search

The effect on H⁻ ion production by adding cesium or xenon to a hydrogen discharge, in a small magnetically filtered multicusp ion source, has been investigated. Addition of cesium vapor to the hydrogen discharge resulted in a factor of 16 increase in H⁻ output relative to the uncesiated discharge for the same operating parameters. Likewise, the addition of xenon gas

S. R. Walther; K. N. Leung; W. B. Kunkel

1988-01-01

321

Production of H? ions with addition of cesium or xenon to a hydrogen discharge in a small multicusp ion source  

Microsoft Academic Search

The effect on H? ion production by adding cesium or xenon to a hydrogen discharge, in a small magnetically filtered multicusp ion source, has been investigated. Addition of cesium vapor to the hydrogen discharge resulted in a factor of 16 increase in H? output relative to the uncesiated discharge for the same operating parameters. Likewise, the addition of xenon gas

S. R. Walther; K. N. Leung; W. B. Kunkel

1988-01-01

322

Study of emission of a volume nanosecond discharge plasma in xenon, krypton and argon at high pressures  

Microsoft Academic Search

The emission properties of a volume nanosecond discharge plasma produced in xenon, krypton and argon at high pressures in a discharge gap with a cathode having a small radius of curvature are studied. Spectra in the range 120850 nm and amplitudetime characteristics of xenon emission at different regimes and excitation techniques are recorded and analysed. It is shown that upon

E Kh Baksht; Mikhail I Lomaev; D V Rybka; Viktor F Tarasenko

2006-01-01

323

Chemical technologies for exploiting and recycling carbon dioxide into the value chain.  

PubMed

While experts in various fields discuss the potential of carbon capture and storage (CCS) technologies, the utilization of carbon dioxide as chemical feedstock is also attracting renewed and rapidly growing interest. These approaches do not compete; rather, they are complementary: CCS aims to capture and store huge quantities of carbon dioxide, while the chemical exploitation of carbon dioxide aims to generate value and develop better and more-efficient processes from a limited part of the waste stream. Provided that the overall carbon footprint for the carbon dioxide-based process chain is competitive with conventional chemical production and that the reaction with the carbon dioxide molecule is enabled by the use of appropriate catalysts, carbon dioxide can be a promising carbon source with practically unlimited availability for a range of industrially relevant products. In addition, it can be used as a versatile processing fluid based on its remarkable physicochemical properties. PMID:21866580

Peters, Martina; Khler, Burkhard; Kuckshinrichs, Wilhelm; Leitner, Walter; Markewitz, Peter; Mller, Thomas E

2011-08-22

324

Carbon dioxide foam flooding  

Microsoft Academic Search

A method of conducting an enhanced oil recovery process in a subterranean reservoir is described. There is injected into the reservoir as a sweep fluid a foam containing carbon dioxide, water, and a foaming agent having the formula ROCOCHSOOM, where R is a straight chain alkyl radical having from 10 to 16 carbon atoms, and M is an alkali metal

P. W. Fischer; L. W. Holm; D. S. Pye

1978-01-01

325

Carbon Dioxide Removal  

NSDL National Science Digital Library

In this experiment using sprigs of Elodea, learners will observe a natural process that removes carbon dioxide (CO2) from Earth's atmosphere. This process is a part of the carbon cycle and results in temperature suitable for life. Note: this experiment requires that learners make observations an hour or the next day after they set up the materials.

History, American M.

2008-01-01

326

Bench Remarks: Carbon Dioxide.  

ERIC Educational Resources Information Center

|Discusses the properties of carbon dioxide in its solid "dry ice" stage. Suggests several demonstrations and experiments that use dry ice to illustrate Avogadro's Law, Boyle's Law, Kinetic-Molecular Theory, and the effects of dry ice in basic solution, in limewater, and in acetone. (TW)|

Bent, Henry A.

1987-01-01

327

Carbon dioxide fixation.  

National Technical Information Service (NTIS)

Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO(sub 2) conv...

E. Fujita

2000-01-01

328

Aqueous carbon dioxide monitor  

Microsoft Academic Search

This patent describes an apparatus for measuring low levels of carbon dioxide in water sample. It comprises: means for exchanging cations for hydrogen connected to a sample stream; a first membrane separator connected to the cation exchanging means, the first membrane separator having a first and second compartment with the first and second compartments being separated by a membrane, the

1991-01-01

329

Calibration of a liquid xenon detector with {sup 83}Kr{sup m}  

SciTech Connect

We report the preparation of a {sup 83}Kr{sup m} source and its use in calibrating a liquid xenon detector. {sup 83}Kr{sup m} atoms were produced through the decay of {sup 83}Rb and introduced into liquid xenon. Decaying {sup 83}Kr{sup m} nuclei were detected through liquid xenon scintillation. Conversion electrons with energies of 9.4 and 32.1 keV from the decay of {sup 83}Kr{sup m} were observed. This calibration source will allow the characterization of the response of noble liquid detectors at low energies. {sup 83}Kr{sup m} may also be useful for measuring fluid flow dynamics, both to understand purification in noble liquid-based particle detectors, as well as for studies of classical and quantum turbulence in superfluid helium.

Kastens, L. W.; Cahn, S. B.; Manzur, A.; McKinsey, D. N. [Department of Physics, Yale University, Post Office Box 208120, New Haven, CT 06520 (United States)

2009-10-15

330

The effect of caesium and xenon addition on negative hydrogen ion production  

SciTech Connect

The presence of caesium in hydrogen discharges is known to increase the extracted negative hydrogen ion current by up to sixteen fold. The mechanism for this phenomenon is not understood. Here Langmuir probe and photodetachment techniques have been used to measure the effects on plasma parameters, including the negative ion density, of adding caesium and xenon to a multicusp ion source. The addition of xenon, also a heavy element but unreactive, allows possible negative ion confinement effects to be explored. No significant change in the negative ion density was observed when up to 20{percent} xenon was introduced, although other plasma parameter changes were observed. Caesium addition increased the negative ion concentration. This increase was found to depend on the wall temperature. {copyright} {ital 1996 American Institute of Physics.}

Steen, P.G.; Graham, W.G. [Department of Pure and Applied Physics, Queen`s University of Belfast, Belfast BT7 1NN (Northern Ireland)

1996-07-01

331

Progress on the Characterization of the Yale ``PIXeY'' Two-Phase Xenon Detector  

NASA Astrophysics Data System (ADS)

PIXeY (Particle Identification in Xenon at Yale) is a two-phase (liquid/gas) xenon prototype detector with 3-kg active mass. The two-phase xenon technology has many applications that include gamma-ray imaging, neutrinoless double beta decay searches, and dark matter searches. PIXeY was built to optimize energy resolution and gamma/neutron discrimination, with a number of technological improvements over previous work. Parallel-wire grids, which control the drift and proportional-scintillation fields, are optimized both for light collection efficiency and field uniformity. High quantum efficiency Hamamatsu R8778 PMTs, high-reflectivity Teflon walls, and charge-light anti-correlation techniques are also incorporated. PIXeY will serve as a platform for future improvements, including multiple optical volumes and single wire readout for R&D on gamma-ray imaging and track-imaging studies. The latest progress on the detector will be presented.

Destefano, Nicholas; Gai, Moshe; McKinsey, Daniel; Bernard, Ethan; Cahn, Sidney; Curioni, Alessandro; Edwards, Blair; Kachulis, Christopher; Larsen, Nicole; Lyashenko, Alexey; Nikkel, James; Skin, Yunchang; Wahl, Christopher; Young, Alexander

2012-10-01

332

The neutron background of the XENON100 dark matter search experiment  

NASA Astrophysics Data System (ADS)

The XENON100 experiment, installed underground at the Laboratori Nazionali del Gran Sasso, aims to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering off xenon nuclei. This paper presents a study on the nuclear recoil background of the experiment, taking into account neutron backgrounds from (?, n) reactions and spontaneous fission due to natural radioactivity in the detector and shield materials, as well as muon-induced neutrons. Based on Monte Carlo simulations and using measured radioactive contaminations of all detector components, we predict the nuclear recoil backgrounds for the WIMP search results published by the XENON100 experiment in 2011 and 2012, 0.11^{+0.08}_{-0.04} events and 0.17^{+0.12}_{-0.07} events, respectively, and conclude that they do not limit the sensitivity of the experiment.

Aprile, E.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Balan, C.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, A.; Brown, E.; Bruno, G.; Budnik, R.; Cardoso, J. M. R.; Chen, W.-T.; Choi, B.; Colijn, A. P.; Contreras, H.; Cussonneau, J. P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Gao, F.; Garbini, M.; Ghag, C.; Giboni, K.-L.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; Kaether, F.; Kish, A.; Lamblin, J.; Landsman, H.; Lang, R. F.; Le Calloch, M.; Levy, C.; Lim, K. E.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Marrodn Undagoitia, T.; Massoli, F. V.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Molinario, A.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Plante, G.; Priel, N.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Scovell, P. R.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Tziaferi, E.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

2013-11-01

333

First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory  

NASA Astrophysics Data System (ADS)

The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon to discriminate signal from background down to 4.5 keV nuclear-recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006, and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross section of 8.810-44cm2 for a WIMP mass of 100GeV/c2, and 4.510-44cm2 for a WIMP mass of 30GeV/c2. This result further constrains predictions of supersymmetric models.

Angle, J.; Aprile, E.; Arneodo, F.; Baudis, L.; Bernstein, A.; Bolozdynya, A.; Brusov, P.; Coelho, L. C. C.; Dahl, C. E.; Deviveiros, L.; Ferella, A. D.; Fernandes, L. M. P.; Fiorucci, S.; Gaitskell, R. J.; Giboni, K. L.; Gomez, R.; Hasty, R.; Kastens, L.; Kwong, J.; Lopes, J. A. M.; Madden, N.; Manalaysay, A.; Manzur, A.; McKinsey, D. N.; Monzani, M. E.; Ni, K.; Oberlack, U.; Orboeck, J.; Plante, G.; Santorelli, R.; Dos Santos, J. M. F.; Shagin, P.; Shutt, T.; Sorensen, P.; Schulte, S.; Winant, C.; Yamashita, M.

2008-01-01

334

Xenon behavior in TiN: A coupled XAS/TEM study  

NASA Astrophysics Data System (ADS)

Titanium nitride is a refractory material that is being considered as an inert matrix in future Generation IV nuclear reactors, in particular in relation to the Gas-cooled Fast Reactor. The main role of this matrix would be to act as a barrier against the release of fission products, in particular gaseous ones like xenon. This release phenomenon will be enhanced by high temperatures expected in the fuel vicinity: 1200 C under normal conditions, and up to 1800 C under accidental conditions. It is therefore necessary to investigate the behavior of volatile fission products in TiN under high temperature and irradiation. Indeed, these basic data are very useful to predict the volatile fission products released under these extreme conditions. Our previous work has shown that Xe introduced by ion implantation in sintered TiN tends to be released as a result of annealing, due to a transport mechanism towards the sample surface. The aim of the present work is to determine under which physical state Xe is in TiN. Xenon was first introduced using ion implantation at 800 keV in TiN samples obtained by hot pressing at several concentrations ranging from 0.4 to 8 at.%. Secondly, samples were annealed at high temperature, from 1000 C to 1500 C. Xe was then characterized by X-ray Absorption Spectroscopy and Transmission Electron Microscopy. The formation of intragranular xenon bubbles was demonstrated, and the xenon concentration which is sufficient to form bubbles is found to be lower than 0.4 at.% under our experimental conditions. These bubbles were found unpressurised at 15 K. Their size increases with the temperature and the local xenon concentration. For the highest xenon concentrations, a mechanism involving the formation of a Xe interconnected bubble network is proposed to explain Xe massive release observed by Rutherford Backscattering Spectrometry experiments.

Bs, R.; Gaillard, C.; Millard-Pinard, N.; Gavarini, S.; Martin, P.; Cardinal, S.; Esnouf, C.; Malchre, A.; Perrat-Mabilon, A.

2013-03-01

335

Collectivity in the light xenon isotopes: A shell model study  

SciTech Connect

The lightest xenon isotopes are studied in the shell model framework, within a valence space that comprises all the orbits lying between the magic closures N=Z=50 and N=Z=82. The calculations produce collective deformed structures of triaxial nature that encompass nicely the known experimental data. Predictions are made for the (still unknown) N=Z nucleus {sup 108}Xe. The results are interpreted in terms of the competition between the quadrupole correlations enhanced by the pseudo-SU(3) structure of the positive parity orbits and the pairing correlations brought in by the 0h{sub 11/2} orbit. We also have studied the effect of the excitations from the {sup 100}Sn core on our predictions. We show that the backbending in this region is due to the alignment of two particles in the 0h{sub 11/2} orbit. In the N=Z case, one neutron and one proton align to J=11 and T=0. In {sup 110,112}Xe the alignment begins in the J=10, T=1 channel and it is dominantly of neutron-neutron type. Approaching the band termination the alignment of a neutron-proton pair to J=11 and T=0 takes over. In a more academic mood, we have studied the role of the isovector and isoscalar pairing correlations on the structure on the yrast bands of {sup 108,110}Xe and examined the possible existence of isovector and isoscalar pairing condensates in these N{approx}{approx}Z nuclei.

Caurier, E.; Nowacki, F.; Sieja, K. [IPHC, IN2P3-CNRS et Universite Louis Pasteur, F-67037 Strasbourg (France); Poves, A. [Departamento de Fisica Teorica e IFT-UAM/CSIC, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)

2010-12-15

336

Performance improvement of 150-mN xenon ion thrusters  

NASA Astrophysics Data System (ADS)

Research was conducted to establish basic xenon ion thruster technology for future applications. In an iterative design and test process to improve thruster performance, four thrusters of three designs were fabricated: the first laboratory model mark 1 (LM-1-MK-1), the first laboratory model mark 2 (LM-1-MK-2), the second laboratory model (LM-2), and the first breadboard model (BBM-1). Performance targets were a thrust of 150 mN, a specific impulse of 3500 s, and an ion production cost less than 150 W/ A at 90% propellant utilization. Magnet temperature was limited to 200C. The LM-1-MK-1 thruster used a 30 cm diameter two-grid system, with azimuthal springs in the grid supports to absorb thermal expansion, a discharge chamber with double sidewalls, an inner effective chamber and an outer magnet yoke. Test results showed an ion production cost of 178 W/ A. The LM-1-MK-2 thruster was designed to give more stable operation and lower magnet temperatures, with a resulting maximum magnet temperature of 254C. The LM-2 thruster used axial springs in the grid supports and a discharge chamber with a single soft-iron wall. It gave an ion production cost of 168 W/ A and a magnet temperature of 240C. The BBM-1 thruster used a 35 cm diameter three-grid system for longer life. The grid fabrication method was improved to achieve greater grid aperture dimensional accuracy. This thruster achieved the performance targets with an ion production cost of 134 W/ A and a magnet temperature of 172C.

Kitamura, Shoji; Miyazaki, Katsuhiro; Hayakawa, Yukio; Yoshida, Hideki; Akai, Kouseki

2003-01-01

337

Angular correlations in the sequential two-photon double ionisation of atomic xenon  

NASA Astrophysics Data System (ADS)

The sequential two-photon double ionization has been analyzed for the 4d electrons of atomic xenon in the region of the giant resonance and beyond (70-200 eV), for which intense FEL radiation is available at the free electron laser FLASH. The 4d vacancies in xenon couple strongly to the autoionization continuum with lifetimes of only a few fs, and their Auger decay thus competes with the subsequent (second-and higher-step) photoionization in typical FEL pulses.

Fritzsche, S.; Grum-Grzhimailo, A. N.; Gryzlova, E. V.; Kabachnik, N. M.

2012-11-01

338

Results from the XENON10 and the Race to Detect Dark Matter with Noble Liquids  

ScienceCinema

Detectors based on liquid noble gases have the potential to revolutionize the direct search for WIMP dark matter. The XENON10 experiment, of which I am a member, has recently announced the results from it's first data run and is now the leading WIMP search experiment. This and other experiments using xenon, argon and neon have the potential to rapidly move from the current kg-scale target mass to the ton scale and well beyond. This should allow a (nearly) definitive test or discovery of dark matter if it is in the form of weakly interacting massive particles.

339

Diagnosing on plasma plume from xenon Hall thruster with collisional-radiative model  

SciTech Connect

The collisional-radiative model for xenon is used to calculate the electron density and temperature, and the atom population distribution in the plasma plume from a xenon Hall thruster. In the calculation, 173 levels of atom population are considered; only the processes of electron induced excitation and deexcitation, and spontaneous decay are simulated. The plasma plume is assumed to be optically thin. Consequently, the reasonable parameters of plasma plume along the outside center line of the thruster channel are obtained by making the calculated emission spectrum corresponding to measured ones and based on the atomic data available on site and by codes.

Yang Juan [College of Astronautics, Northwestern Polytechnic University, Xi'an 710072 (China); Yokota, Shigeru; Kaneko, Ryotaro; Komurasaki, Kimiya [Department of Aeronautics and Astronautics, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-8656 (Japan)

2010-10-15

340

Effect of nonlocal electron kinetics on the characteristics of a dielectric barrier discharge in xenon  

SciTech Connect

The established dynamics of a dielectric barrier discharge in xenon at a pressure of 400 Torr is simulated in the framework of a one-dimensional fluid model in the local and nonlocal field approximations. It is shown that taking into account the nonlocal character of the electric field does not qualitatively change physical processes in a dielectric barrier discharge, but significantly affects its quantitative characteristics. In particular, the sheath thickness decreases, plasma ionization intensifies, the spatiotemporal distribution of the mean electron energy changes, and the discharge radiation efficiency increases. Electron kinetics in a dielectric barrier discharge in xenon is analyzed using the nonlocal field approximation.

Avtaeva, S. V.; Skornyakov, A. V. [Kyrgyz-Russian Slavic University (Kyrgyzstan)

2009-07-15

341

Isotopic fractionation during subsurface xenon transport after a below ground nuclear test  

NASA Astrophysics Data System (ADS)

Xenon transport through porous systems is critical to predicting how this gas will enter the atmosphere after a below ground nuclear weapons test. The ratio of specific xenon isotopes is used as a marker for determining whether test a has been conducted. It has generally been assumed that time is the only factor affecting the isotopic rations. Using a barometric cycling model, we show that gas transport itself can affect the ratios and cause them to drift outside the bounds that are used to establish whether a test has taken place.

Deinert, M. R.

2011-12-01

342

A sealed high pressure xenon filled imaging proportional counter with a sensitive area 30cm square  

SciTech Connect

The performance of an imaging proportional counter (IPC) 30cm square is evaluated in this paper. The scaling effects involved in the construction of such a device were investigated using an electrode array along and a xenon-methane filled IPC. In the IPC, a spatial resolution of 1.2mm FWHM was achieved; and as expected this limitation is shown not to be due to the electronic signal to noise ratio, but to the widely dispersed secondary avalanches initiated by ultra violet photons emitted by excited xenon atoms.

Thomas, H.D.; Turner, M.J.L.

1983-02-01

343

Boltzmann expansion in a radiofrequency conical helicon thruster operating in xenon and argon  

NASA Astrophysics Data System (ADS)

A low pressure (~0.5 mTorr in xenon and ~1 mTorr in argon) Boltzmann expansion is experimentally observed on axis within a magnetized (60 to 180 G) radiofrequency (13.56 MHz) conical helicon thruster for input powers up to 900 W using plasma parameters measured with a Langmuir probe. The axial forces, respectively, resulting from the electron and magnetic field pressures are directly measured using a thrust balance for constant maximum plasma pressure and show a higher fuel efficiency for argon compared to xenon.

Charles, C.; Boswell, R.; Takahashi, K.

2013-06-01

344

Heat capacity and thermal expansion of cryocystalline xenon at elevated temperatures  

NASA Astrophysics Data System (ADS)

The behavior of the heat capacity and thermal expansion of solid xenon (crystals of a rare gas) is studied in the range of elevated temperatures. It is found that the relative width of the premelting zone for xenon exceeds that for other solids. The Xe premelting parameters are estimated using the single-vacancy model. The results of this study explain the known difficulties encountered in the description of thermodynamic properties of solid inert gases using simple model potentials of the interatomic interaction of the Lennard-Jones type by the fact that premelting effects are not taken into account correctly.

Bodryakov, V. Yu.

2013-05-01

345

Modeling of the catalytic properties of high-temperature surface insulation in a dissociated carbon dioxide Nitrogen mixture  

Microsoft Academic Search

A model of the heterogeneous catalysis of a dissociated carbon dioxide nitrogen mixture on high-temperature heat-shield\\u000a coatings is developed; the model takes into account nonequilibrium adsorption-desorption reactions of nitrogen and oxygen\\u000a atoms and carbon dioxide molecules and their recombination in the Eley-Rideal reactions. On the basis of a comparison of the\\u000a calculated heat fluxes in dissociated carbon dioxide with

N. E. Afonina; V. G. Gromov; V. L. Kovalev

2000-01-01

346

Influence of different gases used for laparoscopy (helium, carbon dioxide, room air, xenon) on tumor volume, proliferation, and apoptosis  

Microsoft Academic Search

Background: Previous reports suggest that helium pneumoperitoneum used for laparoscopic surgery suppresses postoperative tumor growth. The present study was designed to determine the effects of gases used in laparoscopy on tumor volume, proliferation, and apoptosis in rats with implanted malignoma. Methods: In 36 rats Morris hepatoma 3294A cells were implanted intrahepatically. Then, after 5 days, they underwent laparoscopy using helium

S. Dhn; P. Schwalbach; F. Whleke; A. Benner; C. Kuntz

2003-01-01

347

Production of uranium dioxide  

Microsoft Academic Search

A continuous, four stage fluidized bed process for converting uranium hexafluoride (UF) to ceramic-grade uranium dioxide (UO) powder suitable for use in the manufacture of fuel pellets for nuclear reactors is disclosed. The process comprises the steps of first reacting UF with steam in a first fluidized bed, preferably at about 550°C, to form solid intermediate reaction products UOF, UO

J. E. Hart; D. L. Shuck; W. L. Lyon

1977-01-01

348

Balancing Atmospheric Carbon Dioxide  

Microsoft Academic Search

ABSTRACT Rising carbon dioxide and global temperatures are causing increasingworldwide concern, and pressure towards an internationallaw of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rainforests, and Caribbean coral reefs suggest that the biological,effects,of climate,change,may,be more,severe,than,climate,models,predict. Efforts to limit

J. Goreau

349

Titanium dioxide photocatalysis  

Microsoft Academic Search

Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO2), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with

Akira Fujishima; Tata N. Rao; Donald A. Tryk

2000-01-01

350

Axial effects of xenon-samarium poisoning in the advanced test reactor  

Microsoft Academic Search

The paper details an analytical study of the time-dependent behavior in the spatial distributions of xenon and samarium fission product poisons in the Advanced Test Reactor (ATR) during operation and after shutdown. The results of this study provide insight into the behavior and significance of the changing spatial distributions of fission product poisons with respect to the prediction of shim

D. J. Auslander; A. C. Smith; R. T. McCracken

1990-01-01

351

Magic Numbers for Sphere Packings: Experimental Verification in Free Xenon Clusters  

Microsoft Academic Search

The existence of magic numbers for atomic microclusters has been found experimentally for the first time. The magic numbers n* manifest themselves in the mass spectra of free xenon clusters, nucleated in the gas phase. The observed numbers n*=13, 55, and 147 coincide with the numbers of spheres required for complete-shell icosahedra. The appearance of further magic numbers (19, 25,

O. Echt; K. Sattler; E. Recknagel

1981-01-01

352

Improvement in time and space resolution of stroboscopic micrography using high power xenon flash  

NASA Astrophysics Data System (ADS)

A circuit capable of regulating 300-W xenon flash tubes up to at 5000 flashes per second (fps) using an insulated gate bipolar transistor (IGBT) as a gating device is presented. This device enables the microscopic analysis of ciliary movement at very high temporal and spatial resolutions, revealing slow and fast phases of angular change during the effective stroke of a single cilium.

Miyake, Momoko O.; Mogami, Yoshihiro; Kataoka, Eri; Kajita, Eri; Baba, Shoji A.

1998-01-01

353

Collective acceleration of xenon ions in a plasma-anode vircator  

NASA Astrophysics Data System (ADS)

The collective acceleration of xenon ions in a plasma-anode vircator is studied. It is shown that the energy of accelerated ions may reach 900 MeV. The image of a bremsstrahlung source on the target suggests effective transport of relativistic electrons in the drift channel.

Chelpanov, V. I.; Golyakov, P. I.; Kornilov, V. G.; Volkov, A. A.; Dubinov, A. E.; Selemir, V. D.; Zhdanov, V. S.

2009-01-01

354

Penile xenon (/sup 133/Xe) washout: a rapid method of screening for vasculogenic impotence  

SciTech Connect

The radioactive inert gas xenon (/sup 133/Xe) is a well-established isotopic indicator used to assess vascular status in many organ systems. Xenon-133 was used to evaluate male impotence. Xenon-133 was injected subcutaneously at the level of the coronal sulcus in the detumescent state. Using the gamma camera, sequential images were obtained and computer-generated curves calculated. The clearance time for 50 per cent washout of the injected /sup 133/Xe (T1/2) was then calculated for each patient, as well as a control group. Preliminary findings indicate a correlation with such established techniques of evaluating erectile impotence as history, physical examination, penile pulse Doppler tracings, and brachial-penile blood pressure index. The xenon-133 washout study was a rapid, minimally invasive, reproducible, and cost-effective method of screening those impotent patients for vasculogenic etiology of their erectile impotence. We recommend the addition of this method to the surgeon engaged in the care of impotent males.

Nseyo, U.O.; Wilbur, H.J.; Kang, S.A.; Flesh, L.; Bennett, A.H.

1984-01-01

355

Higgs searches and singlet scalar dark matter: Combined constraints from XENON 100 and the LHC  

NASA Astrophysics Data System (ADS)

XENON100 and the LHC are two of the most promising machines to test the physics beyond the standard model. In the meantime, indirect hints push us to believe that the dark matter and Higgs boson could be the two next fundamental particles to be discovered. Whereas ATLAS and CMS have just released their new limits on the Higgs searches, XENON100 obtained very recently strong constraints on dark matter-proton elastic scattering. In this work, we show that when we combined WMAP and the most recent results of XENON100, the invisible width of the Higgs to scalar dark matter is negligible (?10%), except in a small region with very light dark matter (?10GeV) not yet excluded by XENON100 or around 60 GeV where the ratio can reach 50% to 60%. The new results released by the Higgs searches of ATLAS and CMS set very strong limits on the elastic scattering cross section, even restricting it to the region 810-46cm2??S-pSI?210-45cm2 in the hypothesis 135GeV?MH?155GeV.

Mambrini, Yann

2011-12-01

356

A Theoretical Investigation of Isotopic Anomalies of Xenon in Terrestrial and Extra-Terrestrial Samples.  

National Technical Information Service (NTIS)

The abundance and isotopic composition of noble gases in meteorites is discussed in relation to the composition of the early solar system. Carbonaceous chondrites contain a unique Xenon-X, which is rich in heavy and light isotopes. Variations in the occur...

D. D. Sabu

1977-01-01

357

Isotopes of tellurium, xenon and krypton in Allende meteorite retain record of nucleosynthesis  

Microsoft Academic Search

Various mixtures of r-, p- and s-nucleosynthesis products have been observed in the isotopes of tellurium, xenon and krypton extracted from mineral separates of the Allende meteorite. The presence of several isotopically distinct components in these high Z elements and the close association of isotopically normal low Z elements with particular isotopes of the high Z elements suggest that our

R. V. Ballad; L. L. Oliver; R. G. Downing; O. K. Manuel

1979-01-01

358

A new approach to decipher the origin of the carbonaceous chondrite fission krypton and xenon  

Microsoft Academic Search

It is suggested that the carbonaceous chondrite fission krypton and xenon, as measured in the primitive meteorites, may have been produced by nuclear fission induced by CNO flare particles in the few-MeV\\/nucleon energy range on very heavy target elements such as Au, Hg, Tl, Pb, and Bi. It is speculatively proposed that the locale of this process has been the

H. W. Mueller; O. A. Schaeffer

1978-01-01

359

A clinical comparison of Technegas and xenon-133 in 50 patients with suspected pulmonary embolus.  

PubMed

A comparison of "Technegas" and xenon-133 was performed in 50 patients presenting with a clinical diagnosis of pulmonary embolus. All patients underwent studies with xenon inhalation, Technegas inhalation, and macroaggregated albumin perfusion. Technegas is a new ultrafine ventilatory agent with a particle size of 50 to 200A produced from technetium pertechnetate and graphite in an argon environment. Although particulate in nature, Technegas is transported and diffuses like a gaseous agent. Its production results in a high specific activity yield with high efficiency. There is no significant deposition in the central airways, and good peripheral visualization of the lung is obtained. The study was designed to assess whether Technegas could be used as a ventilatory agent to obtain high-quality diagnostic images. All studies were reported as in normal clinical practice, and no statistical analysis was performed. The aim of the study was simply to see what role Technegas had in a busy clinical department and how well it reflected ventilation by comparison with xenon. Patient compliance with Technegas was 100 percent and for xenon was 94 percent. Technegas enables one to obtain high-quality ventilatory images and has an important role to play in the assessment of pulmonary ventilation. PMID:2840245

Sullivan, P J; Burke, W M; Burch, W M; Lomas, F E

1988-08-01

360

Radio-controlled xenon flashers for atmospheric monitoring at the HiRes cosmic ray observatory  

Microsoft Academic Search

Stable, robust ultraviolet light sources for atmospheric monitoring and calibration pose a challenge for experiments that measure air fluorescence from cosmic ray air showers. One type of light source in use at the High Resolution Fly's Eye (HiRes) cosmic ray observatory features a xenon flashbulb at the focal point of a spherical mirror to produce a 1 ?s pulse of

L. R. Wiencke; T. Abu-Zayyad; M. Al-Seady; K. Belov; D. J. Bird; J. Boyer; G. F. Chen; R. W. Clay; H. Y. Dai; B. R. Dawson; P. Denholm; J. Gloyn; D. He; Y. Ho; M. A. Huang; C. C. H. Jui; M. J. Kidd; D. B. Kieda; B. Knapp; S. Ko; K. Larson; E. C. Loh; E. J. Mannel; J. N. Matthews; J. R. Meyer; A. Salman; K. M. Simpson; J. D. Smith; P. Sokolsky; D. Steenblik; J. K. K. Tang; S. Taylor; S. B. Thomas; C. R. Wilkinson

1999-01-01

361

Glioblastoma blood flow measured with stable xenon CT indicates tumor necrosis, vascularity, and brain invasion  

PubMed Central

Tumor vasculature is a promising therapeutic target in glioblastoma. Imaging tumor blood flow may help assess the efficacy of anti-angiogenic treatments. We determined the clinical usefulness of stable xenon CT performed preoperatively in patients with glioblastoma. This is a prospective cohort study. We determined absolute tumor blood flow before surgery in 38 patients with glioblastoma using stable xenon CT. We also histologically examined tumor specimens obtained from surgery and quantified their vascularity (by CD31 and CD105 immunostain), necrosis (by hematoxylin and eosin stain), and the presence of neuronal processes (by neurofilament immunostain). According to the xenon CT blood flow map, there are 3 types of glioblastoma. Type I glioblastomas have unimodal high blood flow histograms; histologically there is little necrosis and vascular proliferation. Type II glioblastomas have unimodal low blood flow histograms; histologically there is prominent necrosis and vascular proliferation. We propose that in type II glioblastoma, the abnormal vessels induced by hypoxia are inefficient at promoting blood flow. Type III glioblastomas have multimodal blood flow histograms. Histologically there is significant neuronal tissue within the tumor. Patients with type III glioblastomas were more likely to develop a post-surgical deficit, consistent with the inclusion of normal tissue within the tumor. Preoperative measurement of absolute blood flow with stable xenon CT in patients with glioblastoma predicts key biological features of the tumor and may aid surgical planning.

Crocker, Matthew; Saadoun, Samira; Jury, Alexa; Jones, Chris; Zacharoulis, Stergios; Thomas, Samiwel; Zwiggelaar, Reyer; Bridges, Leslie R.; Bell, B. Anthony; Papadopoulos, Marios C.

2012-01-01

362

Differential Sputtering Behavior of Pyrolytic Graphite and Carbon-Carbon Composite Under Xenon Bombardment.  

National Technical Information Service (NTIS)

A differential sputter yield measurement technique is described, which consists of a quartz crystal monitor that is swept at constant radial distance from a small target region where a high current density xenon ion beam is aimed. This apparatus has been ...

J. D. Williams M. L. Johnson D. D. Williams

2003-01-01

363

Xenon-129 NMR study of the microporous structure of clays and pillared clays.  

National Technical Information Service (NTIS)

(sup 129)Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diam...

C. Tsiao K. A. Carrado

1990-01-01

364

Characteristics of the 2.65 {mu}m atomic xenon laser  

SciTech Connect

The laser characteristics of the 2.65 {mu}m xenon laser transition are reviewed. Measured and extrapolated laser efficiency in nuclear pumped and electron beam pumped system is reported. Previous research has indicated that the reported power efficiency is between 0.1 and 2 percent.

Hebner, G.A.

1995-10-01

365

Background estimation of the XENON1T Dark Matter Search Experiment  

NASA Astrophysics Data System (ADS)

We will present the background estimation of the XENON1T detector, the next generation of the XENON phased Dark Matter search program. Detailed studies of both the electronic recoil and nuclear recoil background have been performed, including irreducible contamination from pp chain solar neutrinos and 2???-decay of ^136Xe.By exploiting the excellent self-shielding and 3D position resolution of a LXeTPC, by selecting existing low radioactivity detector materials and by placing the detector in a large active water shield and Cherenkov muon veto, the overall event rate within the fiducial target of 1.1 ton is estimated to be less than 0.5 10-4 events/kg/day/keVee. This rate translates to less than one event per ton per year in the WIMP search region -- an unprecedented low background level for a dark matter experiment. For a ?SI10-45 cm^2 and 100 GeV/c^2 WIMP mass, XENON1T would detect of order 100 events in this exposure, providing statistics for placing significant constraints on the WIMP mass. In the absence of signal XENON1T would be capable of probing WIMP interaction cross-sections to ?SI2x10-47cm^2 within 2 years of operation.

Beltrame, Paolo

2012-03-01

366

New Results from The Search for Dark Matter with XENON100  

NASA Astrophysics Data System (ADS)

We report new results from the XENON100 dark matter experiment searching for WIMPs. Operating underground at the LNGS in Italy, XENON100 is a dual phase (liquid/gas) time projection chamber containing a total of 161 kg liquid xenon (LXe) with a 62 kg WIMP target mass and 99 kg shield. Initial results obtained from only 11.2 days of data acquired during a commissioning period at the end of 2009 resulted in world-competitive limits on the WIMP-nucleon interaction cross-section. With no evidence of signal, recently published results from 100.9 live-days set the most stringent limit on dark matter interactions to date, excluding cross-sections above 7.0E-45 cm^2 for a 50 GeV/c^2 WIMP mass at 90% C.L. Following this exposure, in the Summer of 2010, XENON100 was filled with Xe processed through a dedicated cryogenic distillation column to reduce Kr background to levels demonstrated in the 11.2 day commissioning period. The trigger threshold was also lowered and the electron lifetime has improved. Blinded data taking was resumed under these conditions. With excellent stability and performance throughout, the exposure approaches 200 live days at the time of writing. Results from this 200 day WIMP search dataset will be presented.

Aprile, Elena

2012-03-01

367

Time-Resolved Spectroscopic Measurements Behind Incident and Reflected Shock Waves in Air and Xenon.  

National Technical Information Service (NTIS)

Time-resolved spectra have been obtained behind incident and reflected shock waves in air and xenon at initial pressures of 0.1 and 1.0 torr using a rotating drum spectrograph and the OSU (The Ohio State University) arc-driven shock tube. These spectra we...

T. Yoshinaga

1973-01-01

368

Absorption Spectra of Krypton and Xenon in Their Regions of Autoionization.  

National Technical Information Service (NTIS)

The absorption cross section spectra of krypton and xenon, obtained at narrow spectral bandwidths are reported. Both gases were studied in their regions of autoionization, 840 to 880 A and 918 to 990 A for Kr and Xe, respectively. In Kr over the entire wa...

R. D. Hudson V. L. Carter

1973-01-01

369

State parameters of pulse-discharge plasma in xenon-filled closed tube  

Microsoft Academic Search

In a diagnostic study of pulse-discharge plasma in xenon flash tubes, the state parameters of such a plasma were measured in an experiment by spectroscopic methods. The plasma temperature was determined from the spectral density, brightness, and absorptivity in accordance with the Kirchhoff-Planck law. The plasma density and pressure were determined in two independent ways, first on the basis of

V. Ye. Gavrilov

1987-01-01

370

Exploring new 129Xe chemical shift ranges in HXeY compounds: hydrogen more relativistic than xenon.  

PubMed

Among rare gases, xenon features an unusually broad nuclear magnetic resonance (NMR) chemical shift range in its compounds and as a non-bonded Xe atom introduced into different environments. In this work we show that (129)Xe NMR chemical shifts in the recently prepared, matrix-isolated xenon compounds appear in new, so far unexplored (129)Xe chemical shift ranges. State-of-the-art theoretical predictions of NMR chemical shifts in compounds of general formula HXeY (Y = H, F, Cl, Br, I, -CN, -NC, -CCH, -CCCCH, -CCCN, -CCXeH, -OXeH, -OH, -SH) as well as in the recently prepared ClXeCN and ClXeNC species are reported. The bonding situation of Xe in the studied compounds is rather different from the previously characterized cases as Xe appears in the electronic state corresponding to a situation with a low formal oxidation state, between I and II in these compounds. Accordingly, the predicted (129)Xe chemical shifts occur in new NMR ranges for this nucleus: ca. 500-1000 ppm (wrt Xe gas) for HXeY species and ca. 1100-1600 ppm for ClXeCN and ClXeNC. These new ranges fall between those corresponding to the weakly-bonded Xe(0) atom in guest-host systems (? < 300 ppm) and in the hitherto characterized Xe molecules (? > 2000 ppm). The importance of relativistic effects is discussed. Relativistic effects only slightly modulate the (129)Xe chemical shift that is obtained already at the nonrelativistic CCSD(T) level. In contrast, spin-orbit-induced shielding effects on the (1)H chemical shifts of the H1 atom directly bonded to the Xe center largely overwhelm the nonrelativistic deshielding effects. This leads to an overall negative (1)H chemical shift in the range between -5 and -25 ppm (wrt CH(4)). Thus, the relativistic effects induced by the heavy Xe atom appear considerably more important for the chemical shift of the neighbouring, light hydrogen atom than that of the Xe nucleus itself. The predicted NMR parameters facilitate an unambiguous experimental identification of these novel compounds. PMID:22782133

Lantto, Perttu; Standara, Stanislav; Riedel, Sebastian; Vaara, Juha; Straka, Michal

2012-07-10

371

Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded Micromegas in Xenon Gas  

NASA Astrophysics Data System (ADS)

Micromegas is a type of micro-pattern gaseous detector currently under R&D for applications in rare event search experiments. Here we report the performance of a Micromegas structure constructed with a micromesh thermo-bonded to a readout plane, motivated by its potential application in two-phase xenon detectors for dark matter and neutrinoless double beta decay experiments. The study is carried out in pure xenon at room temperature. Measurements with alpha particles from the Americium-241 source showed that gas gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays down to 8 keV were observed with such a device.

Wei, Yuehuan; Guan, Liang; Zhang, Zhiyong; Lin, Qing; Wang, Xiaolian; Ni, Kaixuan; Zhao, Tianchi

2013-08-01

372

Simultaneous Measurement of Ionization and Scintillation from Nuclear Recoils in Liquid Xenon for a Dark Matter Experiment  

SciTech Connect

We report the first measurements of the absolute ionization yield of nuclear recoils in liquid xenon, as a function of energy and electric field. Independent experiments were carried out with two dual-phase time-projection chamber prototypes, developed for the XENON dark matter project. We find that the charge yield increases with decreasing recoil energy, and exhibits only a weak field dependence. These results are the first unambiguous demonstration of the capability of dual-phase xenon detectors to discriminate between electron and nuclear recoils down to 20 keV, a key requirement for a sensitive dark matter search.

Aprile, E.; Giboni, K. L.; Majewski, P.; Ni, K.; Yamashita, M. [Physics Department and Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States); Dahl, C. E.; Kwong, J. [Department of Physics, Princeton University, Princeton, New Jersey 08540 (United States); Viveiros, L. de; Gaitskell, R. J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Shutt, T. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States)

2006-08-25

373

Phase behavior of mixed submonolayer films of krypton and xenon on graphite.  

PubMed

Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two- and three-dimensional models of the systems studied. It has been demonstrated that out-of-plane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit non-monotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Two-dimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (?3?3)R30 phase upon the increase of temperature. Such a superstructure does not appear when a three-dimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the krypton-like (with incipient triple point) to the xenon-like (with ordinary triple point). PMID:22502538

Patrykiejew, A; Soko?owski, S

2012-04-14

374

Phase behavior of mixed submonolayer films of krypton and xenon on graphite  

NASA Astrophysics Data System (ADS)

Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two- and three-dimensional models of the systems studied. It has been demonstrated that out-of-plane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit non-monotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Two-dimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (33)R30 phase upon the increase of temperature. Such a superstructure does not appear when a three-dimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the krypton-like (with incipient triple point) to the xenon-like (with ordinary triple point).

Patrykiejew, A.; Soko?owski, S.

2012-04-01

375

A WIMP detector with two-phase xenon to search for dark matter  

NASA Astrophysics Data System (ADS)

In this thesis I would like to introduce an experimental approach to solve the dark matter problem that is one of the hottest unsolved physics problems today. I have been involved for several years to solve that problem in UCLA- Torino Dark Matter search team at CERN, Geneva. The UCLA- Torino dark matter team is searching for the Super Symmetric dark matter particle named neutralino, that is a candidate for the WIMPs (Weakly Interactive Massive Particles). So, many parts of this thesis will be filled with description of the dark matter search work of the UCLA-Univ. of Torino collaboration with 1-kg two-phase xenon detector that was supposed to be mounted at the laboratory in the middle of the Mt. Blanc tunnel with an expecting event rate of 3 ~ 4 events/kg/day. Even though most physicists believe the existence of dark matter, I would like to review the inventory of the dark matter in the universe, cosmological approach for the dark matter, and astrophysical approach for that problem in the first few chapters. I will introduce the already found evidences of the non-baryonic dark matter, for example MACHO, gravitational lensing, super nova, etc. Theoretical approaches and several direct detection methods will be reviewed also. The direct WIMPs searching detectors need the extremely powerful background discrimination because there is a huge amount of background in that energy range of dark matter signal. Xenon and xenon detector meet all the requirements well for the background rejection. Especially, a two-phase xenon WIMP detector provides much better background rejection than a single phase one. Also we will show the outstanding effect of the electroluminescence plates with CsI internal photo cathode that magnify the primary scintillation and increase the efficiency of the background rejection. Applying the CsI internal photo cathode to the xenon WIMP detector is one of major topics for this dissertation.

Woo, Jong-Kwan

2000-08-01

376

Ion-Molecule Reactions in Gas Phase Radiation Chemistry.  

ERIC Educational Resources Information Center

|Discusses some aspects of the radiation chemistry of gases, focusing on the ion-molecule and charge neutralization reactions which set study of the gas phase apart. Uses three examples that illustrate radiolysis, describing the radiolysis of (1) oxygen, (2) carbon dioxide, and (3) acetylene. (CS)|

Willis, Clive

1981-01-01

377

21 CFR 172.480 - Silicon dioxide.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 2009-04-01 false Silicon dioxide. 172.480 Section 172.480 ...CONSUMPTION Anticaking Agents § 172.480 Silicon dioxide. The food additive silicon dioxide may be safely used in food in...

2009-04-01

378

21 CFR 172.480 - Silicon dioxide.  

Code of Federal Regulations, 2010 CFR

...3 2010-01-01 2009-04-01 true Silicon dioxide. 172.480 Section 172.480 ...CONSUMPTION Anticaking Agents § 172.480 Silicon dioxide. The food additive silicon dioxide may be safely used in food in...

2010-01-01

379

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 2009-04-01 false Silicon dioxide. 573.940 Section 573.940 ...ANIMALS Food Additive Listing § 573.940 Silicon dioxide. The food additive silicon dioxide may be safely used in animal feed...

2009-04-01

380

The Multiphoton Multiple Ionization of Molecules.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The multiphoton multiple ionization of a number of molecular systems has been studied using the picosecond laser facility at the Rutherford Appleton Laboratory. The laser produced 0.6ps pulses at 600nm, and 6ps at 248nm when used in conjunction with an excimer laser. The focused intensity in each case was >=q10 ^{15}W/cm^2 . A time of flight mass spectrometer designed and built at Reading University was capable of ion kinetic energy measurement, permitting the molecular dissociation dynamics to be investigated. One major question approached concerned the mode of multiphoton ionization of xenon. Specifically, does the ionization proceed in a sequential (single electron) or a collective (many electron) manner? To this end, experiments were performed with the isoelectronic molecule hydrogen iodide. The results, which were interpreted in terms of a Coulomb explosion mechanism, demonstrated the process to be sequential, rather than collective. Similar experiments on the isoelectronic pair, nitrogen and carbon monoxide tended to confirm this conclusion. These molecules were also studied at a number of laser wavelengths and pulse widths. Although the wavelength was found to have a minimal effect, the pulse width was of great importance. The results for hydrogen and deuterium contrasted with these results for other molecules, in that the energies could not be reconciled with a Coulomb explosion mechanism. Rather, dissociative autoionization or neutral dissociation followed by ionization of the atoms were considered to be the dominant processes. Finally, the existence of high energy protons (~eq100eV) from residual hydrocarbons in the vacuum chamber lead to a study of the alkanes from butane to dodecane. At 600nm, 0.6ps pulse width, the fragment energies were found to vary linearly with carbon chain length. At 248nm, 5ps though, only low energy protons were observed, independent of chain length.

Hatherly, P. A.

381

Focused electron-beam-induced etching of silicon dioxide  

SciTech Connect

Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO{sub 2} matrix, and subsequently rate limited by XeF{sub 2} availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO{sub 2} to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

Randolph, S.J.; Fowlkes, J.D.; Rack, P.D. [University of Tennessee, Department of Materials Science and Engineering, 434 Dougherty Engineering Building, Knoxville, Tennessee 37996-2200 (United States)

2005-08-01

382

[Action modes of chlorine dioxide--a review].  

PubMed

Chlorine dioxide (ClO2) is a highly effective disinfectant for food and potable water treatment. Till now, the action mode of ClO2 is still unclear. ClO2, can denature proteins by oxidizing tyrosine, tryptophan, and cysteine. We reviewed the pathways by which ClO02 reacts with important bio-molecules, as well as the primary target sites at individual cellular level of ClO2-induced biocidal effects. PMID:22799207

Wei, Mingken; Lai, Jieling; Zhan, Ping

2012-04-01

383

Carbon dioxide and climate  

SciTech Connect

Scientific and public interest in greenhouse gases, climate warming, and global change virtually exploded in 1988. The Department's focused research on atmospheric CO{sub 2} contributed sound and timely scientific information to the many questions produced by the groundswell of interest and concern. Research projects summarized in this document provided the data base that made timely responses possible, and the contributions from participating scientists are genuinely appreciated. In the past year, the core CO{sub 2} research has continued to improve the scientific knowledge needed to project future atmospheric CO{sub 2} concentrations, to estimate climate sensitivity, and to assess the responses of vegetation to rising concentrations of CO{sub 2} and to climate change. The Carbon Dioxide Research Program's goal is to develop sound scientific information for policy formulation and governmental action in response to changes of atmospheric CO{sub 2}. The Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1990 and gives a brief overview of objectives, organization, and accomplishments.

Not Available

1990-10-01

384

Aspects of carbon dioxide utilization  

Microsoft Academic Search

Carbon dioxide reacts with hydrogen, alcohols, acetals, epoxides, amines, carboncarbon unsaturated compounds, etc. in supercritical carbon dioxide or in other solvents in the presence of metal compounds as catalysts. The products of these reactions are formic acid, formic acid esters, formamides, methanol, dimethyl carbonate, alkylene carbonates, carbamic acid esters, lactones, carboxylic acids, polycarbonate (bisphenol-based engineering polymer), aliphatic polycarbonates, etc. Especially,

Iwao Omae

2006-01-01

385

Coral reefs and carbon dioxide  

SciTech Connect

This commentary argues the conclusion from a previous article, which investigates diurnal changes in carbon dioxide partial pressure and community metabolism on coral reefs, that coral `reefs might serve as a sink, not a source, for atmospheric carbon dioxide.` Commentaries from two groups are given along with the response by the original authors, Kayanne et al. 27 refs.

Buddemeier, R.W. [Kansas Geological Survey, Lawrence, KS (United States)

1996-03-01

386

Carbon dioxide absorption methanol process  

Microsoft Academic Search

This patent describes a process for removing carbon dioxide from a feed stream of natural gas having at least methane, ethane and heavier. It comprises: first, separating the feed stream in a first separator to form a first stream having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane and a second stream, having methane, carbon

Apffel

1989-01-01

387

Radioactive plume from the Three Mile Island accident: xenon-133 in air at a distance of 375 kilometers  

Microsoft Academic Search

As a result of the Three Mile Island nuclear reactor accident in March 1979, the passage of radioactive xenon-133 through Albany, N.Y., was monitored from March 29-April 2, 1979. Monitoring techniques are described. Ambient air Xenon-133 concentrations as high as 3900 pico Ci\\/cu m were recorded. The local gamma ray whole body dose from the passing radioactivity amounted to 0.004

M. Wahlen; C. O. Kunz; J. M. Matuszek; W. E. Mahoney; R. C. Thompson

1980-01-01

388

Compton scattering sequence reconstruction algorithm for the liquid xenon gamma-ray imaging telescope (LXeGRIT)  

Microsoft Academic Search

The Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT) is a balloon born experiment sensitive to (gamma) -rays in the energy band of 0.2 - 20 MeV. The main detector is a time projection chamber filled with high purity liquid xenon (LXeTPC), in which the three-dimensional location and energy deposit of individual (gamma) -ray interactions are accurately measured in one homogeneous volume.

Uwe G. Oberlack; Elena Aprile; Alessandro Curioni; Valeri Egorov; Karl-Ludwig Giboni

2000-01-01

389

Method for dehydrating manganese dioxide  

SciTech Connect

A method is described for preparing a water-free lithium-manganese dioxide battery comprising: assembling the battery comprising lithium anode, a cathode comprising carbon and manganese dioxide, and a cell container; adding to the cell container a fluid containing a dehydrating agent which reacts with water bound to the manganese dioxide to form a reaction product that is extractable from the manganese dioxide; removing the fluid from the cell container; hermetically sealing and connecting the container to a vacuum source; establishing a vacuum within the compartment to pull off any remaining amount of the fluid and any volatile reaction product from the manganese dioxide; releasing the vacuum; and adding anhydrous electrolyte and hermetically sealing the cell.

Marincic, N.; Fuksa, R.

1987-05-05

390

The Development of the improved equipment for the measurement radionuclides of xenon in atmospheric air  

NASA Astrophysics Data System (ADS)

The Radium Khlopin Institute have developed the mobile (vehicle based) equipment attended for the providing of the monitoring of radioactive xenon isotopes in atmospheric air on territories, neighboring with NPP. This equipment comprises the improved sampling installation with sample-processing unit and specialized spectrometer of ?-?-coincidences. The principal specificity of sampling installation is the using of the gas-cooling machine attended for the reaching of the cryogenic temperatures, which works without helium, using for cooling the processed air itself. The capacity of sampling reaches 20 cubic meters per hour with the xenon extraction factor of 75%. The duration of the sampling cycle forms 3 - 7 hours depending of the xenon volume requirements. The sample-processing unit is designed on preparative gas chromatograph scheme. Duration of sample-processing procedure does not exceed one and half hour. The volume of the prepared sample is around half liter, it contains 3 - 7 cubic centimeters of the xenon, depending of sampling cycle time. For measurements of xenon radioisotopes containing in obtained sample, was developed a ?-?-coincidences spectrometer on the base of the "ORTEC" HP Ge detector equipped with scintillation ?-detector designed as Marinelli chamber of 700 cm3 volume. This spectrometer allows to reduce the ambient background more than in 20 times, with ?-channel efficiency reduction not more than in 1.5 times. The minimum detectable activity of 133?? (MDA), evaluated by Currie formula for probability 95 % is 0.05 Bq at the exposition of 20 hours. Spectrometer is also intended for determination of the stable krypton and xenon concentrations in ?-chamber by X-ray-fluorescent method. Therefore, in a shield of the spectrometer collimating pinhole is made and 241Am source is installed. To improve the sensitivity of the analysis beryllium window is made in ?-chamber wall, adjoining to the HPGe detector. X-ray-fluorescent analysis allows to surely define Xe volumetric concentration of 0.05% in ?-cell, that is equivalent less then 0,5 cm3 of Xe. The first approbation of described equipment was fulfilled in St. Petersburg at autumn of 2007 year and have shown that the spectrometer allows to measure 133Xe concentration at the level of 2 mBq/m3, and this value is in a good agreement with the results of other measurements. Described equipment was practically approbated in field conditions on 2008 year during the expeditionary work carryout in Sosnovyi Bor, Udomlya and Polyarnie Zori - the cities of North-West of Russia, which are located in close neighboring with acting NPP.

Pakhomov, S. A.; Dubasov, Y. V.

2009-04-01

391

Anatomic applications of xenon-enhanced CT scanning: visual image analysis and brain-blood partition coefficient studies in man.  

PubMed

The inhalation of nonradioactive xenon, an inert gas that diffuses freely across the blood-brain barrier, resulted in brain enhancement which was quantitated and visualized by computed tomography (CT). Serial CT scans obtained during the buildup and equilibrium phase of xenon inhalation were used in a numerical and visual analysis of xenon accumulation in multiple selected gray- and white-matter regions in 12 patients. The calculated brain-blood partition coefficient (lambda) in normal gray matter was 0.92 +/- 0.11 and in normal white matter, 1.38 +/- 0.14. Asymmetries and delays in xenon enhancement were often visually apparent. The estimated partition coefficient was diminished more with cerebral infarction, intracerebral hematoma, and vasogenic edema than with hypoxic encephalopathy or glioblastoma multiforme. An increase in the rate of xenon accumulation was apparent by visual inspection of the motor cortex contralateral to complex hand movements. Technical factors and potential difficulties in conducting xenon-enhanced CT studies are discussed. PMID:6410801

Drayer, B P; Friedman, A; Osborne, D; Albright, R; Bates, M

392

Cage Reactions of T-Butoxy Radicals. Effects of Viscosity and of Intervening Molecules.  

National Technical Information Service (NTIS)

The effects of changes in viscosity on amounts of cage DPB (t-BuOO-t-Bu) produced from DBPO (t-BuOOCOCOOO-t-Bu), from DBH (t-BuON-NO-t-Bu), and from DBP itself are reported. The presence of a nitrogen molecule or two carbon dioxide molecules in the cage c...

H. Kiefer T. G. Traylor

1968-01-01

393

Oxidation of plutonium dioxide.  

PubMed

The physics and chemistry of the actinide elements form the scientific basis for rational handling of nuclear materials. In recent experiments, most unexpectedly, plutonium dioxide has been found to react with water to form higher oxides up to PuO(2.27), whereas PuO(2) had always been thought to be the highest stable oxide of plutonium. We perform a theoretical analysis of this complicated situation on the basis of total energies calculated within density functional theory combined with well-established thermodynamic data. The reactions of PuO(2) with either O(2) or H(2)O to form PuO(2+delta) are calculated to be endothermic: that is, in order to occur they require a supply of energy. However, our calculations show that PuO(2+delta) can be formed, as an intermediate product, by reactions with the products of radiolysis of water, such as H(2)O(2). PMID:15034561

Korzhavyi, Pavel A; Vitos, Levente; Andersson, David A; Johansson, Brje

2004-03-14

394

Carbon dioxide: atmospheric overload  

SciTech Connect

The level of carbon dioxide in the atmosphere is increasing and may double within the next century. The result of this phenomenon, climatic alterations, will adversely affect crop production, water supplies, and global temperatures. Sources of CO2 include the combustion of fossil fuels, photosynthesis, and the decay of organic matter in soils. The most serious effect of possible climatic changes could occur along the boundaries of arid and semiarid regions. Shifts is precipitation patterns could accelerate the processes of desertification. An increase of 5..cap alpha..C in the average temperature of the top 1000 m of ocean water would raise sea level by 2 m. CO2 releases to the atmosphere can be reduced by controlling emissions from fossil fuel-fired facilities and by careful harvesting of forest regions. (3 photos, 5 references)

Not Available

1980-04-01

395

Determining reactor flux from xenon-136 and cesium-135 in spent fuel  

NASA Astrophysics Data System (ADS)

The ability to infer reactor flux from spent fuel or seized fissile material would enhance the tools of nuclear forensics and nuclear nonproliferation significantly. We show that reactor flux can be inferred from the ratios of xenon-136 to xenon-134 and cesium-135 to cesium-137. If the average flux of a reactor is known, the flux inferred from measurements of spent fuel could help determine whether that spent fuel was loaded as a blanket or close to the mid-plane of the reactor. The cesium ratio also provides information on reactor shutdowns during the irradiation of fuel, which could prove valuable for identifying the reactor in question through comparisons with satellite reactor heat monitoring data. We derive analytic expressions for these correlations and compare them to experimental data and to detailed reactor burn simulations. The enrichment of the original uranium fuel affects the correlations by up to 3%, but only at high flux.

Hayes, A. C.; Jungman, Gerard

2012-10-01

396

Real-time Detection of Polymerization Reactions with Hyperpolarized Xenon at Low Magnetic Fields  

NASA Astrophysics Data System (ADS)

For process control it is desirable to develop simple devices for studying polymerization reactions in real-time and in-situ. We are demonstrating an approach using NMR at fields as low as 35 G and hyperpolarized xenon, which allows us to observe polymerization reactions in real-time. The investigated reaction is a free radical polymerization with the initiator azobisisobutyronitrile (AIBN) and the monomer methyl methacrylate (MMA). AIBN and MMA are mixed together in a sample tube under noble gas atmosphere, and the reaction is started by irradiation with UV light (360 nm). As the reaction goes on, xenon NMR spectra are acquired. They show increasing line broadening and a variation of the chemical shift depending on the state of polymerization. This observation gives rise to the idea that a single-sided high resolution NMR sensor can be developed with which at least light induced polymerization reactions can be studied in-situ and in real-time.

Glggler, Stefan; Blmich, Bernhard; Appelt, Stephan

2011-03-01

397

Flash xenon CPV simulator with low-cost elastic bent-trough mirrors  

NASA Astrophysics Data System (ADS)

In the research and development of concentrator photovoltaic (CPV) systems, a highly collimated artificial sunlight source with a wide irradiated area is very helpful in the reliable evaluation of module efficiency and optical performance. To collimate the light, a conventional flash xenon CPV simulator uses an expensive large concave mirror. This paper introduces a new flash xenon CPV simulator that consists of two low-cost elastic bent-trough mirrors. The prototype simulator achieved an irradiance deviation of less than 10%, collimation of 0.228 - 0.330, and good spectral matching at an irradiated area of 700 mm 500 mm. The major drawback of the present concept is that the flash lamp must provide higher emissive power than the conventional method because of the light attenuation caused by the two reflections from the mirrors.

Yamada, Noboru; Okamoto, Kazuya; Ijiro, Toshikazu; Kiryu, Mitsugu; Yoshida, Takanori

2013-09-01

398

Wavelength and Intensity Dependence of Short Pulse Laser Xenon Double Ionization between 500 and 2300 nm  

SciTech Connect

The wavelength and intensity dependence of xenon ionization with 50 fs laser pulses has been studied using time-of-flight mass spectrometry. We compare the ion yield distribution of singly and doubly charged xenon with the Perelomov-Popov-Terent'ev (PPT) theory, Perelomov, Popov, and Terent'ev, Zh. Eksp. Teor. Fiz. 50, 1393 (1966) [Sov. Phys. JETP 23, 924 (1966)], in the regime between 500 and 2300 nm. The intensity dependence for each wavelength is measured in a range between 1x10{sup 13} and 1x10{sup 15} W/cm{sup 2}. The Xe{sup +}-ion signal is in good agreement with the PPT theory at all used wavelengths. In addition we demonstrate that ionic 5s5p{sup 6} {sup 2}S state is excited by an electron impact excitation process and contributes to the nonsequential double ionization process.

Gingras, G.; Tripathi, A.; Witzel, B. [Centre d'Optique, Photonique et Laser, Universite Laval, Pavillon d'optique-photonique Quebec (Quebec), G1V 0A6 (Canada)

2009-10-23

399

Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge  

NASA Astrophysics Data System (ADS)

A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s'[1/2]10-6p'[3/2]2 xenon atomic transition at ? = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

MacDonald, N. A.; Cappelli, M. A.; Hargus, W. A.

2012-11-01

400

The XENON10 WIMP Direct Detection Search at the Gran Sasso Underground Laboratory  

SciTech Connect

The direct detection search for WIMPs with the XENON10 detector has produced among the best results in the field to date. The detector is a dual-phase liquid xenon time projection chamber, capable of 3-D position reconstruction and nuclear recoil discrimination. We summarize 58.6 live-days of WIMP search data collected at the Gran Sasso Underground Laboratory (LNGS) in Italy. With this data we have been able to set stringent upper limits on the spin-dependent and spin-independent WIMP scattering cross sections, in addition to a lower limit of 2.2 TeV/c{sup 2} on the mass of the heavy Majorana neutrino.

Manalaysay, Aaron [Department of Physics, University of Florida, Gainesville, FL 32611 (United States) and Physics Institute, University of Zuerich, Zuerich, CH-8057 (Switzerland)

2009-09-08

401

RF Noise Generation in High-Pressure Short-Arc DC Xenon Lamps  

NASA Astrophysics Data System (ADS)

Continuous direct current xenon arcs will generate RF noise under certain circumstance, which can lead to excessive electro- magnetic interference in systems that use these arcs as light sources. Phenomenological observations are presented for xenon arcs having arc gaps 1 mm, cold fill pressures of 2.5 MPa, and currents up to 30 amps. Using a loop antenna in the vicinity of an operating lamp, it is observed that as the current to the arc is lowered there is a reproducible threshold at which the RF noise generation begins. This threshold is accompanied by a small abrupt drop in voltage (0.2 volts). The RF emission appears in pulses 150 nsec wide separated by 300 nec - the pulse interval decreases with decreasing current. The properties of the RF emission as a function of arc parameters (such as pressure, arc gap, electrode design) will be discussed and a semi-quantitative model presented.

Minayeva, Olga; Doughty, Douglas

2007-10-01

402

Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge  

SciTech Connect

A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s{sup Prime }[1/2]{sub 1}{sup 0}-6p{sup Prime }[3/2]{sub 2} xenon atomic transition at {lambda}= 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

MacDonald, N. A.; Cappelli, M. A. [Stanford Plasma Physics Laboratory, Stanford University, Stanford, California 94305 (United States); Hargus, W. A. Jr. [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)

2012-11-15

403

Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge.  

PubMed

A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s(')[1/2](1)(0)-6p(')[3/2](2) xenon atomic transition at ? = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz. PMID:23206061

MacDonald, N A; Cappelli, M A; Hargus, W A

2012-11-01

404

Limits on Spin-Dependent WIMP-Nucleon Cross Sections from the XENON10 Experiment  

SciTech Connect

XENON10 is an experiment to directly detect weakly interacting massive particles (WIMPs), which may comprise the bulk of the nonbaryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with {sup 129}Xe and {sup 131}Xe from 58.6 live days of operation at the Laboratori Nazionali del Gran Sasso. Based on the nonobservation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of {approx}10 GeV/c{sup 2}-2 TeV/c{sup 2} as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

Angle, J. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Physics Institute, University of Zuerich, Zuerich, CH-8057 (Switzerland); Aprile, E.; Giboni, K. L.; Monzani, M. E.; Plante, G.; Santorelli, R.; Yamashita, M. [Department of Physics, Columbia University, New York, New York 10027 (United States); Arneodo, F. [INFN-Laboratori Nazionali del Gran Sasso, Assergi, 67100 (Italy); Baudis, L.; Ferella, A. D. [Physics Institute, University of Zuerich, Zuerich, CH-8057 (Switzerland); Bernstein, A.; Madden, N.; Winant, C. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Bolozdynya, A.; Dahl, C. E.; Kwong, J.; Shutt, T. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Coelho, L. C. C.; Fernandes, L. M. P.; Lopes, J. A. M. [Department of Physics, University of Coimbra, Coimbra 3004-516 (Portugal)] (and others)

2008-08-29

405

PERFORMANCE OF A LIQUID XENON CALORIMETER CRYOGENIC SYSTEM FOR THE MEG EXPERIMENT  

SciTech Connect

The {mu}-particle rare decay physics experiment, the MU-E-GAMMA (MEG) experiment, will soon be operational at the Paul Scherrer Institute in Zurich. To achieve the extremely high sensitivity required to detect gamma rays, 800 L of liquid xenon is used as the medium in the calorimeter, viewed by 830 photomultiplier tubes (PMT) immersed in it. The required liquid xenon purity is of the order of ppb of water, and is obtained by using a cryogenic centrifugal pump and cold molecular sieves. The heat load of the calorimeter at 165 K is to be approximately 120 W, which is removed by a pulse-tube cryocooler developed at KEK and built by Iwatani Industrial Gas Corp., with a cooling power of about 200 W at 165 K. The cryogenic system is also equipped with a 1000-L dewar. This paper describes the results of an initial performance test of each cryogenic component.

Haruyama, T.; Kasami, K. [KEK, High Energy Accelerator Research Organization 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Hisamitsu, Y.; Iwamoto, T.; Mihara, S.; Mori, T.; Nishiguchi, H.; Otani, W.; Sawada, R.; Uchiyama, Y. [ICEPP, University of Tokyo 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Nishitani, T. [Iwatani Industrial Gases Corp. Moriyama, Shiga (Japan)

2008-03-16

406

Measurement of the scintillation reponse of liquid xenon to electronic recoils down to low energies  

NASA Astrophysics Data System (ADS)

Understanding the electronic recoil response in liquid xenon (LXe) is important for the interpretation of results from dark matter experiments using LXe such as XENON100 and to estimate the electronic background contributions. As the first step, the energy dependence of the scintillation response at zero field was measured with a dedicated LXe detector. The scintillation response of LXe has been measured in the past at different energies using mono-energetic ? sources. However, the Compton coincidence technique has the added benefit that the response can be measured at a continuum of energies. In this work, Compton scattered ? rays were used to measure the scintillation light yield from electronic recoils below 100 keV. The high scintillation light collection of the detector enabled the lowest recoil energies to be probed to date. A comparison with the decays of Kr-83m is also presented.

Lim, Kyungeun E.; Aprile, E.; Budnik, R.; Choi, B.; Contreras, H. A.; Giboni, K.-L.; Goetzke, L. W.; Koglin, J.; Lang, R. F.; Melgarejo Fernandez, A. J.; Persiani, R.; Plante, G.; Rizzo, A.

2012-03-01

407

Molecular dynamics simulations of carbon dioxide and water at an ionic liquid interface.  

PubMed

The ionic liquid-carbon dioxide system is of interest because ionic liquids (ILs) have potential to be used for carbon dioxide capture. Because water will be present in a real carbon dioxide capture operation, the interaction between water and the IL is also of interest. Classical molecular dynamics simulations have been used to study the IL 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmim-Tf(2)N) at the interface with vacuum as well as with carbon dioxide, water, or both present in the system. Density and orientational ordering of the ionic liquid molecules at the interface was not significantly altered by the presence of either carbon dioxide or water. The structure of the liquid solutions in the pseudobulk region in the center of the slab was studied using metrics of pairwise association such as radial distribution functions. At the interface, there is an increased density of cation-anion association. When carbon dioxide is present, it forms a dense layer on the surface, and the cation-anion associations at the interface are disrupted, with a corresponding decrease in surface tension. Water slows down the diffusion of the ions as well as carbon dioxide in the bulk. Water has little effect, however, on the interfacial transport dynamics of carbon dioxide. PMID:21800915

Perez-Blanco, Marcos E; Maginn, Edward J

2011-08-15

408

Photokilling of T-24 human bladder cancer cells with titanium dioxide.  

PubMed Central

A photoexcited titanium dioxide surface has a strong ability to decompose water into hydrogen and oxygen. We have studied this effect in order to use it to kill cancer cells in vitro and in vivo. A distinct cell killing effect was observed on cultured T-24 human bladder cancer cells treated with titanium dioxide particles and 300-400 nm UV light irradiation. Titanium dioxide plus UV light also dramatically suppressed the tumour growth of T-24 cells that were implanted in nude mice. Cells cultured on the titanium dioxide electrode were also killed under UV irradiation when the electrode was anodically polarised, suggesting that photogenerated holes are involved in the cell killing. The cell killing effect caused by titanium dioxide particles plus UV light irradiation was significantly hampered in the presence of L-cysteine and catalase, scavengers of hydroxyl radicals and hydrogen peroxide respectively. Transmission electron microscopic observations showed the titanium dioxide particles to be distributed on the cell surface and inside the cells. These results suggest that titanium dioxide particles under UV light irradiation produced photogenerated holes on the surface yielding hydroxyl radicals and hydrogen peroxide inside or outside the cells and the cells were then killed by the action of these highly oxidising molecules. The possible application of photoexcited titanium dioxide particles to cancer treatment as a new anti-cancer modality is discussed. Images Figure 6

Kubota, Y.; Shuin, T.; Kawasaki, C.; Hosaka, M.; Kitamura, H.; Cai, R.; Sakai, H.; Hashimoto, K.; Fujishima, A.

1994-01-01

409

Single polarity charge sensing in high pressure xenon using a coplanar anode configuration  

NASA Astrophysics Data System (ADS)

A new design of a high pressure xenon ionization chamber has been fabricated in an attempt to eliminate the problems associated with acoustical vibrations of the Frisch grid. The function of the traditional Frisch grid has been accomplished by employing a coplanar anode system capable of single polarity charge sensing by means of the Shockley-Ramo theorem. Two different detectors have been built in order to determine if the operation of a high pressure xenon detector in coplanar anode mode is possible. The first is the helical detector comprised of two anode wires wound about a central ceramic core. Through calculation, it is shown that for a cathode bias of -5 kV a potential of 363 V is necessary to collect all of the electrons on the collecting anode, however this is contradicted by the observed pulse waveforms. The results of several experiments are presented that demonstrate the helical detector should work, however in the interest in determining if a coplanar high pressure xenon detector is viable, emphasis was placed on the second detector design. The second design is a parallel plate detector, more analogous to the coplanar semiconductor devices. This detector has demonstrated that it is possible to operate a high pressure xenon detector in coplanar anode mode. However, it is shown that the performance of this detector is limited by high surface leakage current and detector capacitance. Additionally, since the leakage current increases with potential between the two anodes, it is not possible to obtain very high resolution gamma-ray spectroscopy since the required potential between the two anodes for coplanar operation is so high that the detector is already dominated by surface leakage current as this value.

Sullivan, Clair Julia

410

Status of the liquid-xenon-jet laser-plasma source for EUV lithography  

NASA Astrophysics Data System (ADS)

The liquid-xenon-jet laser-plasma source is one of the extreme-ultraviolet (EUV) source technologies under development for EUV lithography. This paper presents some recent improvements of the technology, including the ability to operate a stable plasma at a distance of 50 mm from the nozzle, the first positive mirror-lifetime results, and improved laser-to-EUV conversion efficiency of 0.75 percent at lambda equals 13.45 nm.

Hansson, Bjoern A.; Rymell, Lars; Berglund, Magnus; Hemberg, Oscar E.; Janin, Emmanuelle; Thoresen, Jalmar; Mosesson, Sofia; Wallin, Johan; Hertz, Hans M.

2002-07-01

411

Renal blood flow measured with xenon-133 wash-out technique and with an electromagnetic flowmeter  

Microsoft Academic Search

30 simultaneous measurements of the renal cortical blood flow with the xenon-133 wash-out technique and the total renal blood flow with an electromagnetic flowmeter were performed in eight dogs. Renal blood flow was varied over a wide range. A highly significant correlation was found between the two measurements. The slope of the correlation line was 1.18 and the standard error

J. Ladefoged; F. Pedersen; U. Doutheil; P. Deetjen; E. E. Selkurt

1965-01-01

412

New measurement of the relative scintillation efficiency of xenon nuclear recoils below 10 keV  

SciTech Connect

Liquid xenon is an important detection medium in direct dark matter experiments, which search for low-energy nuclear recoils produced by the elastic scattering of WIMPs with quarks. The two existing measurements of the relative scintillation efficiency of nuclear recoils below 20 keV lead to inconsistent extrapolations at lower energies. This results in a different energy scale and thus sensitivity reach of liquid xenon dark matter detectors. We report a new measurement of the relative scintillation efficiency below 10 keV performed with a liquid xenon scintillation detector, optimized for maximum light collection. Greater than 95% of the interior surface of this detector was instrumented with photomultiplier tubes, giving a scintillation yield of 19.6 photoelectrons/keV electron equivalent for 122-keV {gamma} rays. We find that the relative scintillation efficiency for nuclear recoils of 5 keV is 0.14, staying constant around this value up to 10 keV. For higher energy recoils we measure a value of 0.21, consistent with previously reported data. In light of this new measurement, the XENON10 experiment's upper limits on spin-independent WIMP-nucleon cross section, which were calculated assuming a constant 0.19 relative scintillation efficiency, change from 8.8x10{sup -44} cm{sup 2} to 9.9x10{sup -44} cm{sup 2} for WIMPs of mass 100 GeV/c{sup 2}, and from 4.5x10{sup -44} cm{sup 2} to 5.6x10{sup -44} cm{sup 2} for WIMPs of mass 30 GeV/c{sup 2}.

Aprile, E.; Choi, B.; Giboni, K. L.; Lim, K.; Monzani, M. E.; Plante, G.; Santorelli, R.; Yamashita, M. [Department of Physics, Columbia University, New York, New York 10027 (United States); Baudis, L. [Physik-Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Manalaysay, A. [Physik-Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

2009-04-15

413

Intercomparison experiments of systems for the measurement of xenon radionuclides in the atmosphere  

Microsoft Academic Search

Radioactive xenon monitoring is one of the main technologies used for the detection of underground nuclear explosions. Precise and reliable measurements of 131mXe, 133gXe, 133mXe, and 135gXe are required as part of the International Monitoring System for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). For the first time, simultaneous testing of four highly sensitive and automated fieldable radioxenon measurement systems

M. Auer; A. Axelssson; X. Blanchard; Ted W. Bowyer; G. Brachet; I. Bulowski; Y. Dubasov; K. Elmgren; J. P. Fontaine; W. Harms; James C. Hayes; Tom R. Heimbigner; Justin I. McIntyre; Mark E. Panisko; Y. Popov; Anders Ringbom; H. Sartorius; S. Schmid; J. Schulze; Clemens Schlosser; T. Taffary; W. Weiss; B. Wernsperger

2004-01-01

414

Regional cerebral blood flow of patients with focal epilepsy studied using xenon enhanced CT brain scanning  

Microsoft Academic Search

Stable xenon-enhanced X-ray computed tomography (XeCT) was used to measure the regional cerebral blood flow (rCBF) of 12 patients with drug resistant partial epilepsy and a marked unilateral focus on electroencephalography (EEG). Interictal mean rCBF of fixed regions of interest (ROIs) was reduced by 25% in the cortex of the epileptogenic cerebral lobe compared with the same regions on the

D R Fish; T T Lewis; D J Brooks; E Zilkha; R J Wise; B E Kendall

1987-01-01

415

Numerical model of an ac plasma display panel cell in neon-xenon mixtures  

Microsoft Academic Search

We present a self-consistent 1D model of the discharge initiated in an ac plasma display panel cell. The model is based on a two-moments fluid description of electron and ion transport, coupled with Poissons equation, and with a set of kinetic equations characterizing the evolution of the population of excited states leading to UV emission in neon-xenon mixtures. Results are

J. Meunier; Ph. Belenguer; J. P. Boeuf

1995-01-01

416

Neon and xenon isotopes in MORB: implications for the earth-atmosphere evolution  

Microsoft Academic Search

The isotopic composition of neon and xenon measured in MORB glasses confirm significant deviations from atmospheric values. These are (1) 21Ne excesses which are attributed to nucleogenic reactions in the mantle: (2) 20Ne\\/22Ne ratios higher than the air ratio interpreted as an evidence for the occurrence of solar-type Ne at depth: (3) 129Xe and 131-136Xe excesses, attributed to both extinct

Bernard Marty

1989-01-01

417

Isotope shift in xenon by Doppler-free two-photon laser spectroscopy  

Microsoft Academic Search

Isotope shifts and pressure broadening have been measured in the two-photon transition at 249 nm from the 5p61S0 ground level of neutral xenon to a J=0 level of the 5p56p configuration (the 2p5 level in Paschen notation). A continuous-wave tunable dye laser operating at 498 nm with intracavity frequency doubling excited the transition. The work is the first application of

M. D. Plimmer; P. E. G. Baird; C. J. Foot; D. N. Stacey; J. B. Swan; G. K. Woodgate

1989-01-01

418

TOTAL NEUTRON CROSS SECTIONS OF HELIUM, NEON, ARGON, KRYPTON, AND XENON  

Microsoft Academic Search

The total neutron cross sections of the noble gases helium, neon, argon, ; krypton, and xenon were measured for neutron energies from 120 kev to 6.2 Mev and ; from 12.1 Mev to 19.8 Mev by a transmission experiment. The neutrons were ; produced using the Li⁷(p,n)Be⁷, the T(p,n)He³, the D(d,n)He\\/sup ; 3\\/, and the T(d,n)He⁴ reactions in the appropriate

F. J. Vaughn; W. L. Imhof; R. G. Johnson; M. Walt

1960-01-01

419

Spontaneous fission-neutron fission xenon: a new technique for dating geological events.  

PubMed

A method for dating geological samples which uses fission product xenon in a manner similar to the use of radiogenic argon in the 40Ar-39Ar technique has been developed. The results of stepwise heating experiments for a zircon from the Ahaggar region in the Sahara are compared to the geochronology determined by the rubidiumstrontium, uranium-thorium-lead, and potassium-argon dating methods. PMID:17812528

Teitsma, A; Clarke, W B; Allgre, C J

1975-09-12

420

High-Speed Camera Study of the Surface Wave Discharge Propagation in Xenon  

Microsoft Academic Search

The formation and advance of filamentary and diffusive microwave surface wave plasma columns in xenon are studied by means of a high-speed camera. The framing photographs show that the ionization front of the filamentary surface wave discharge exhibits a corona-leader-like behavior. The streak photographs show that during the ionization front propagation, the discharges in both forms are sustained by a

Jozef Kudela; Igor Odrobina; Masashi Kando

1998-01-01

421

Aromatic fluorine derivatives. C. reactions of pentafluorophenol with vanadium, niobium, and antimony fluorides and xenon difluoride  

Microsoft Academic Search

Pentafluorophenol reacts with vanadium fluorides (VF, VOF, VF) and xenon difluoride giving perfluoro-2,5-cyclohexadien-1-one and the products from dimerization of the pentafluorophenoxyl radical, i.e., perfluoro-6-phenoxy-2,4-cyclo-hexadien-1-one, perfluoro-4-phenoxy-2,5-cyclohexadien-1-one, and perfluoro-2-phenoxy-2,5-cyclohexadien-1-one. Antimony and niobium pentafluorides give stable complexes or the corresponding pentafluorophenolates with pentafluorophenol.

A. A. Auramenko; V. V. Bardin; G. G. Furin; A. I. Karelin; V. A. Krasilnikov; P. P. Tushin; G. G. Yakobson

1985-01-01

422

Solubility of krypton, xenon and radon in polycarbonates. Application for measurement of their radioactive isotopes  

Microsoft Academic Search

Bisphenol-A polycarbonates have a high absorption ability for noble gases that can be employed for sampling and measurement of radioactive isotopes of these gases. In this report the solubility of krypton, xenon and radon in the specified polycarbonates is determined by measurement of 85Kr, 133Xe and 222Rn absorbed in polycarbonate specimens. The found solubility is used to develop a general

D. Pressyanov; K. Mitev; I. Dimitrova; S. Georgiev

2011-01-01

423

A high efficiency device for the detection of radioactive xenon isotopes  

Microsoft Academic Search

A detector has been designed for the detection of sub-Becquerel amounts of the radioactive xenon isotopes 131mXe and 133Xe. High efficiency has been obtained by the condensation of the sample directly onto the surfaces of two closely spaced silicon surface-barrier detectors. The measurement of the 131mXe is based on the detection of the conversion electrons. The 133Xe measurement is obtained

G. P. Lamaze

1997-01-01

424

Testing accelerated weathering tests for appropriate weathering chemistry: Ozone filtered xenon arc  

Microsoft Academic Search

Ftir spectroscopy has been used to follow the weathering chemistry of a HALS and UVA free polyester\\/urethane and a HALS and UVA\\u000a free acrylic\\/melamine clearcoat cured on silicon wafers and subjected to exposure in Florida, Arizona, and in a number of\\u000a accelerated weathering tests. All accelerated tests except EMMAQUA-NTW, ozone filtered xenon arc, and 3M Proprietary exposures\\u000a distort the polyester\\/urethanes

J. L. Gerlock; C. A. Peters; A. V. Kucherov; T. Misovski; C. M. Seubert; R. O. Carter; M. E. Nichols

2003-01-01

425

Predictive value of intracutaneous xenon clearance for healing of amputation and cutaneous ulcer sites  

Microsoft Academic Search

A previously reported technique for the assessment of skin blood flow in the lower extremities of patients with ischemic lesions was evaluated using intracutaeous xenon clearance. The radioisotope was injected above and below both the ankle and the knee and flow was measured using a gamma camera with a low-energy collimator, 88-keV photopeak, and a 20% window. Healing was more

E. B. Silberstein; S. Thomas; J. Cline; R. Kempczinski; L. Gottesman

1983-01-01

426

Prospective use of xenon ¹³³Xe clearance for amputation level selection  

Microsoft Academic Search

Xenon ¹³³Xe clearance was used to select the most distal amputation level that would allow sufficient blood flow for healing. Capillary blood flow was first measured at the most distal potential amputation level, then at successive proximal levels until an amputation site was found that had a capillary skin blood flow rate greater than or equal to 2.6 mL\\/min\\/100 g

W. S. Moore; R. E. Henry; J. M. Malone; M. J. Daly; D. Patton; S. J. Childers

1981-01-01

427

Predictive value of intracutaneous xenon clearance for healing of amputation and cutaneous ulcer sites  

Microsoft Academic Search

A previously reported technique for the assessment of skin blood flow in the lower extremities of patients with ischemic lesions was evaluated using intracutaneous xenon clearance. The radioisotope was injected above and below both the ankle and the knee and flow was measured using a gamma camera with a low-energy collimator, 88-keV photopeak, and a 20% window. Healing was more

E. B. Silberstein; S. Thomas; J. Cline; R. Kempczinski; L. Gottesman

1983-01-01

428

High-pressure alloying of iron and xenon: Missing Xe in the Earth's core?  

Microsoft Academic Search

Ab initio quantum mechanical calculations show that xenon (Xe) can be alloyed with hexagonal close-packed iron at high pressure through substitutional incorporation, with a favorable enthalpy of formation for the alloy relative to the separate elemental solids, suggesting that Xe is soluble in the Earth's iron-rich core (up to ?0.8 mol %). This alloying behavior and the possible presence of

Kanani K. M. Lee; Gerd Steinle-Neumann

2006-01-01

429

Spectroscopy and Imaging Performance of the Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT)  

Microsoft Academic Search

LXeGRIT is a balloon-borne Compton telescope based on a liquid xenon time projection chamber (LXeTPC) for imaging cosmic gamma -rays in the energy band 0.2- 20 MeV. The detector, with 400 cm2 area and 7 cm drift gap, is filled with high purity LXe. Both ionization and scintillation light signals are detected to measure the energy deposits and the three

E. Aprile; V. Egorov; K.-L. Giboni; U. G. Oberlack; J. Kikuchi; K. Takizawa; P. P. Dunphy

2000-01-01

430

Deconvolution of ion velocity distributions from laser-induced fluorescence spectra of xenon electrostatic thruster plumes  

Microsoft Academic Search

This thesis presents a method for extracting singly-ionized xenon (Xe II) velocity distribution estimates from single-point laser-induced fluorescence (LIF) spectra at 605.1 nm. Unlike currently-popular curve-fitting methods for extracting bulk velocity and temperature data from LIF spectra, this method makes no assumptions about the velocity distribution, and thus remains valid for non-equilibrium and counterstreaming plasmas. The well-established hyperfine structure and

Timothy B. Smith

2003-01-01

431

HIGH-PRESSURE XENON DETECTORS FOR APPLICATIONS IN PORTAL SAFEGUARD SYSTEMS AND FOR MONITORING NUCLEAR WASTE  

Microsoft Academic Search

Constellation Technology Corporation has developed a family of high-pressure xenon ionization chambers (HPXe) with mass of working medium between 100 g and 2 kg. The detectors demonstrate a good energy resolution (below 3%FWHM at 662 keV for 1 kg detector) that is close to the resolution of room temperature semiconductor detectors. The detectors employ relatively simple design, robust construction, and

Alexander Bolozdynya; Anatoli Arodzero; Ray DeVito

432

Energy and spectral characteristics of the IFP20000 xenon lamp under short-flash conditions  

Microsoft Academic Search

The characteristics of the IFP-20000 xenon flashtubes have been most thoroughly studied in the visible and near-IR regions of the spectrum with flash lifetimes of 0.9-1.5 #sec and specific electric capacities below 0.18 MW\\/cm 3 [1-3]. In those studies the spectral emission yield, the spectral brightness, and the brightness temperature of the discharge were determined experimentally in the 400-1100-nm region

A. S. Kamrukov; G. N. Kashnikov; N. P. Kozlov; V. A. Malashchenko; Yu. S. Protasov

1975-01-01

433

Sound absorption and dispersion as a function of density near the critical point of xenon  

Microsoft Academic Search

Sound velocity and absorption have been measured at frequencies of 0.6, 1, and 3 MHz for xenon along the liquid-vapor coexistence curve and along several near-critical isotherms. By simultaneously measuring the dielectric constant, the local density was determined at the level in the fluid where the ultrasonic results were obtained. The shape of the coexistence curve obtained from dielectric data

Jan Thoen; Carl W. Garland

1974-01-01

434

Radiometric characterization of ultrahigh radiance xenon short-arc discharge lamps  

Microsoft Academic Search

Xenon short-arc discharge lamps exhibit ultrahigh radiance with substantial emission beyond the visible, primarily in the near infrared. Their radiance distributions are spatially and angularly inhomogeneous due to both the structure of the plasma arc and the infrared radiation from the electrodes. These characteristics are favorable for high-irradiance biomedical and high-temperature reactor applications that exploit both visible light and infrared

Doron Nakar; Asher Malul; Daniel Feuermann; Jeffrey M. Gordon

2008-01-01

435

Radiometric characterization of ultra-bright xenon short-arc discharge lamps for novel applications  

Microsoft Academic Search

The latest generations of ultra-bright Xenon short-arc discharge lamps have prodigious emissions outside the visible spectrum, primarily in the near infrared. Their brightness distributions are spatially and angularly inhomogeneous due to both the pronounced non-uniformities of the plasma arc and the substantial infrared radiation from the hot electrodes. These characteristics are fortuitously favorable for applications in photonic surgery, biomedical diagnostics,

Doron Nakar; Asher Malul; Daniel Feuermann; Jeffrey M. Gordon

2007-01-01

436

Structural Plasticity of the Phage P22 Tail Needle gp26 Probed with Xenon Gas  

SciTech Connect

The tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 A resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of alpha-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host.

Olia, A.; Casjens, S; Cingolani, G

2009-01-01

437

Structural plasticity of the phage P22 tail needle gp26 probed with xenon gas  

PubMed Central

The tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of ?-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host.

Olia, Adam S; Casjens, Sherwood; Cingolani, Gino

2009-01-01

438

Virial coefficients of rare gases on xenon-plated graphite using image theory  

NASA Astrophysics Data System (ADS)

The first two virial coefficients and their temperature derivatives for Ne and for Ar atoms adsorbed on xenon-plated graphite are reexamined with the implementation of the Mahantys image theory. On the assumption that the substrate is treated as a good conductor, encouraging values of the second virial coefficient ?2 and the average lateral interaction energy ?2 of an isolated pair of adatoms are obtained when the ideal surface of the substrate is set at 1.9 above the xenon layer, a distance which is essentially identical to the van der Waals radius of the xenon atom. Under such a situation, the strength of the adatom-adatom interaction is weakened by a factor of 0.56 and 0.60 for the Ar and the Ne case, respectively, which are in concord with the predictions asserted in earlier work. Discussions on the dependence on the dielectric constant of the substrate are also given. The present results seem to indicate that the Mahantys theory provides a viable alternative approach for studies of physisorption problems.

Ren, Chung-Yuan; Hsue, Chen-Shiung

2003-03-01

439

Two-photon (vacuum ultraviolet + visible) spectroscopy of argon, krypton, xenon, and molecular hydrogen  

SciTech Connect

Two-photon transitions have been examined in argon, krypton, xenon, and molecular hydrogen using a coherent vacuum ultraviolet (VUV) photon at a fixed wavelength of 118 nm and a tunable photon from a dye laser. The 118 nm VUV photon is produced by third harmonic generation in xenon using UV light at 355 nm from a frequency tripled Nd:YAG laser. Though the VUV intensity is very weak, (approx.100 nJ per pulse) it was utilized very efficiently since most of VUV photons in the ionization region were absorbed. Spectra were obtained in the region of 12.5 to 13.5 eV and the corresponding two-photon rate constants were calculated. This is the first time that coherent VUV light has been employed with tunable visible light for the production of two-photon spectra and the measurement of two-photon rates. The two-photon ionization rate of xenon was measured using photons at fixed wavelengths of 118 and 355 nm. A new parameter is proposed for direct comparison of the data from various two-photon experiments.

McCann, M.P.; Chen, C.H.; Payne, M.G.

1988-11-01

440

Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression.  

PubMed

Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter ? range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to ?6?km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory. PMID:20866920

Zheng, J; Gu, Y J; Chen, Z Y; Chen, Q F

2010-08-03

441

Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression  

SciTech Connect

Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter {Gamma} range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to {approx}6 km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory.

Zheng, J.; Gu, Y. J.; Chen, Z. Y.; Chen, Q. F. [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, P.O. Box 919-102, Mianyang, Sichuan (China)

2010-08-15

442

Measuring Neutron Response using Data and Monte Carlo Simulation in Xenon100  

NASA Astrophysics Data System (ADS)

A relative scintillation yield (Leff) above 5.5 keVr (nuclear recoil energy) is determined using data from an exposure of XENON100 to neutrons from an Americium-Beryilium (AmBe) source. The technique requires a signal in the XENON100 Time Projection Chamber (TPC) to be in coincidence with a signal in the active liquid xenon (LXe) veto such that efficiency to low energy nuclear recoils is not compromised by the requirement of a signal in 2 or more photomultiplier tubes (PMTs). The Leff is then deduced (independently of any Monte Carlo simulation) through the comparison of the scintillation and ionization signals recorded. The calculated Leff is in excellent agreement with recent direct and indirect measurements. Comparison of the detector response to AmBe neutrons with an equivalent Monte Carlo generated spectrum is also performed. With the measured detector efficiency and a global fit to all measured values of Leff, agreement between data and Monte Carlo down to a low photoelectron level is obtained.

Scovell, Paul

2012-03-01

443

Absolute Scintillation Yields in Liquid Argon and Xenon for Various Particles  

NASA Astrophysics Data System (ADS)

For the determination of the absolute scintillation yields the number of scintillation photons per unit absorbed energy for a variety of particles in liquid argon, a series of simultaneous ionization and scintillation measurements were performed. The results verified that scintillation yields for relativistic heavy particles from Ne to La are constant despite their extensive range of linear energy transfer. Such a constant level, called flat top response level, manifests the maximum absolute scintillation yield in liquid argon. The maximum absolute scintillation yield is defined by the average energy to produce a single photon, Wph(max) = 19.5 1.0 eV. In liquid xenon, the existence of the same flat top response level was also found by conducting scintillation measurements on relativistic heavy particles. The Wph(max) in liquid xenon was evaluated to be 13.8 0.9 eV using the Wph for 1 MeV electrons, obtained experimentally. The ratio between the two maximum scintillation yields at the flat top response level obtained in liquid argon and xenon is in good agreement with the estimation by way of the energy resolutions of scintillation due to alpha particles in both liquids.

Doke, Tadayoshi; Hitachi, Akira; Kikuchi, Jun; Masuda, Kimiaki; Okada, Hiroyuki; Shibamura, Eido

2002-03-01

444

Non-Equilibrium Plasma Dynamics Modeling of Xenon Clusters Irradiated by an Intense Laser Pulse  

NASA Astrophysics Data System (ADS)

Population inversions have been experimentally observed when small xenon clusters of 5-20 atoms are irradiated by 230 fs high intensity laser of 10^19 W/cm^2 and wavelength of 248 nm [1]. Consequently, a plasma channel 1.5-2 cm in length and 1.5--2 ?m in diameter is formed which produces amplified x-ray emissions with gains 20-60 for wavelengths in the range 2.71-3 . It has been conjectured [2], that population inversions in laser generated xenon plasmas may be efficiently created within M-shell ionization stages by photo- or collisional-ionization of 2s and 2p inner shell electrons. In this study we focus our attention on the influence of non-Maxwellian electron energy distributions on the collisional dynamics by which hollow atoms are generated in different ionization stages of xenon. These distributions are calculated from a relativistic molecular dynamics model. [4pt] [1] A. B. Borisov, et al., J. Phys. B 40, F307 (2007). [0pt] [2] W. A. Schroeder, et al., J. Phys. B 34, 297 (2001).

Petrova, Tzvetelina; Whitney, Kenneth; Petrov, George; Davis, Jack

2009-11-01

445

Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression  

NASA Astrophysics Data System (ADS)

Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter ? range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to 6km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory.

Zheng, J.; Gu, Y. J.; Chen, Z. Y.; Chen, Q. F.

2010-08-01

446

First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory  

SciTech Connect

The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon to discriminate signal from background down to 4.5 keV nuclear-recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006, and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross section of 8.8x10{sup -44} cm{sup 2} for a WIMP mass of 100 GeV/c{sup 2}, and 4.5x10{sup -44} cm{sup 2} for a WIMP mass of 30 GeV/c{sup 2}. This result further constrains predictions of supersymmetric models.

Angle, J.; Manalaysay, A. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Department of Physics, RWTH Aachen University, Aachen, 52074 (Germany); Aprile, E.; Giboni, K. L.; Monzani, M. E.; Plante, G.; Santorelli, R.; Yamashita, M. [Department of Physics, Columbia University, New York, New York 10027 (United States); Arneodo, F. [INFN-Laboratori Nazionali del Gran Sasso, Assergi, 67010 (Italy); Baudis, L.; Orboeck, J.; Schulte, S. [Department of Physics, RWTH Aachen University, Aachen, 52074 (Germany); Bernstein, A.; Madden, N.; Winant, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Bolozdynya, A.; Brusov, P.; Shutt, T. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Coelho, L. C. C.; Fernandes, L. M. P. [Department of Physics, University of Coimbra, R. Larga, 3004-516, Coimbra (Portugal)] (and others)

2008-01-18

447

Conformational space and photochemistry of tyramine isolated in argon and xenon cryomatrixes.  

PubMed

The infrared spectra of tyramine monomers trapped in low-temperature argon and xenon matrixes were recorded. The presence of the flexible ethylamino side chain gives rise to a complex conformational surface that contains several minima of relatively low energies, some of them stabilized by a weak N-H? hydrogen bond interaction between the amino group and the phenyl ring. The experimental infrared spectra confirm the presence of at least two stable conformers isolated in the matrixes. Annealing experiments performed on the xenon matrix revealed a change in the relative population of the experimentally relevant conformers upon isolation in this polarizable matrix, compared to the gas phase. The general interpretation of the spectra was based on harmonic and anharmonic quantum chemical calculations, undertaken at the DFT/B3LYP and MP2 levels of theory with the 6-311++G(d,p) basis set. The photochemical behavior of the matrix-isolated compound upon narrow-band UV irradiation was also investigated. Identification of ketene species in the spectra of the irradiated matrixes suggests the occurrence of a ring-opening reaction, which in the xenon matrix occurs concomitantly with the conformational isomerization of tyramine. PMID:24011365

Giuliano, Barbara M; Melandri, Sonia; Reva, Igor; Fausto, Rui

2013-09-26

448

Iterative Boltzmann plot method for temperature and pressure determination in a xenon high pressure discharge lamp  

NASA Astrophysics Data System (ADS)

The Boltzmann plot method allows to calculate plasma temperatures and pressures if absolutely calibrated emission coefficients of spectral lines are available. However, xenon arcs are not very well suited to be analyzed this way, as there are only a limited number of lines with atomic data available. These lines have high excitation energies in a small interval between 9.8 and 11.5 eV. Uncertainties in the experimental method and in the atomic data further limit the accuracy of the evaluation procedure. This may result in implausible values of temperature and pressure with inadmissible uncertainty. To omit these shortcomings, an iterative scheme is proposed that is making use of additional information about the xenon fill pressure. This method is proved to be robust against noisy data and significantly reduces the uncertainties. Intentionally distorted synthetic data are used to illustrate the performance of the method, and measurements performed on a laboratory xenon high pressure discharge lamp are analyzed resulting in reasonable temperatures and pressures with significantly reduced uncertainties.

Zalach, J.; Franke, St.

2013-01-01

449

Xenon Purification Research and Development for the LZ Dark Matter Experiment  

NASA Astrophysics Data System (ADS)

The LZ Experiment is a next generation dark matter detector based on the current LUX detector design, with a 7-ton active volume. Although many research and development breakthroughs were achieved for the 350 kg LUX detector, the large volume scaling required for LZ presents a new set of design challenges that need to be overcome. Because the search for WIMP-like dark matter requires ultra low background experiments, the xenon target material in the LZ detector must meet purity specifications beyond what is commercially available. This challenge is two-fold. The xenon must contain extremely low amounts of electronegative impurities such as oxygen, which attenuate the charge signal. Additionally, it must also have very little of the inert isotope Kr-85, a beta-emitter that can obscure the dark matter signal in the detector volume. The purity requirements for the LUX experiment have been achieved, but the factor of 20 scaling in volume for LZ and increased demands for sensitivity mean that new research and development work must be done to increase our xenon purification capabilities. This talk will focus on the efforts being done at Case Western Reserve University to meet these strict purity requirements for the LZ Experiment.

Pech, Katherin

2013-04-01

450

XENON100 implications for naturalness in the MSSM, NMSSM, and ?-supersymmetry model  

NASA Astrophysics Data System (ADS)

In a recent paper [M. Perelstein and B. Shakya, J. High Energy Phys. 10 (2011) 142.], we discuss the correlation between the elastic neutralino-nucleon scattering cross section constrained by dark matter direct-detection experiments and fine-tuning at tree level in the electroweak symmetry breaking sector of the minimal supersymmetric Standard Model (MSSM). Here, we show that the correlation persists in the next-to-minimal supersymmetric Standard Model (NMSSM), and its variant, the ?-supersymmetry (SUSY) model. Both models are strongly motivated by the recent discovery of a 125 GeV Higgs-like particle. We also discuss the implications of the recently published bound on the direct-detection cross section from 225 live days of the XENON100 experiment. In both the MSSM and the NMSSM, most of the parameter space with fine-tuning less than 10% is inconsistent with the XENON100 bound. In the ?-SUSY model, on the other hand, large regions of completely natural electroweak symmetry breaking are still allowed, primarily due to a parametric suppression of fine-tuning with large ?. The upcoming XENON1T experiment will be able to probe most of the parameter space with less than 1% fine-tuning in all three models.

Perelstein, Maxim; Shakya, Bibhushan

2013-10-01

451

State parameters of pulse-discharge plasma in xenon-filled closed tube  

NASA Astrophysics Data System (ADS)

In a diagnostic study of pulse-discharge plasma in xenon flash tubes, the state parameters of such a plasma were measured in an experiment by spectroscopic methods. The plasma temperature was determined from the spectral density, brightness, and absorptivity in accordance with the Kirchhoff-Planck law. The plasma density and pressure were determined in two independent ways, first on the basis of the temperature distribution and the Saha relation, assuming a uniform pressure distribution over the tube volume and a constant gas mass during measurement, then on the basis of the half-width of the spectral absorption line of hydrogen added in small amounts to xenon. The results have been used for evaluating the dependence of the plasma temperature and pressure on the density of the electric discharge current over the 0 to 10 kA/sq cm range under initial xenon pressures of 6.7 to 80 kPa as well as the dependence of the plasma density and pressure on the plasma temperature and of the plasma pressure on the electron concentration and on the discharge power.

Gavrilov, V. Ye.

1987-06-01

452

Skin blood flow from gas transport: helium xenon and laser Doppler compared  

SciTech Connect

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-03-01

453

Greenhouse Gas Molecules  

NSDL National Science Digital Library

This page, from Beloit College, uses a Java application to allow users to view and rotate greenhouse gas molecules. Users may choose to view the molecule as a ball and/or stick model or a spacefill model.

College, Beloit

454

Conformational and structural studies of isopropylamine from temperature dependent Raman spectra of xenon solutions and ab initio calculations  

NASA Astrophysics Data System (ADS)

The Raman and infrared spectra (4000-50 cm-1) of the gas, liquid or solution, and solid have been recorded of isopropylamine, (CH3)2CHNH2. Variable temperature (-50 to -100 C) studies of the Raman spectra (3500-100 cm-1) dissolved in liquid xenon have been carried out. From these data, both the trans and gauche conformers have been identified and their relative stability obtained. The enthalpy difference has been determined to be 113 11 cm-1 (1.35 0.13 kJ mol-1) with the trans conformer the more stable form. The percentage of the gauche conformer is estimated to be 54 1% at ambient temperature. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ from both MP2(full) and density functional theory calculations by the B3LYP method. By utilizing previously reported microwave rotational constants along with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters have been obtained for the trans conformer. The determined heavy atom and NH2 distances are () C-C = 1.530(3), C-N = 1.465(3), N-H = 1.019(3) and angles in degrees () ?NCC = 108.9(5), ?CCC = 111.0(5), ?HNC = 110.3(5). The structural parameters for the gauche conformer were estimated by using the same adjustment differences to the gauche form as those obtained for the corresponding trans parameters. Vibrational assignments have been provided for the observed bands for both conformers which are supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities and depolarization ratios for both conformers. The results are discussed and compared to the corresponding properties of some related molecules.

Durig, James R.; Klaassen, Joshua J.; Darkhalil, Ikhlas D.; Herrebout, Wouter A.; Dom, Johan J. J.; van der Veken, Benjamin J.

2012-02-01

455

Nucleic acid molecule  

US Patent & Trademark Office Database

The invention relates to an isolated nucleic acid molecule encoding a polypeptide capable of producing a triterpenoid hydrocarbon. The invention also relates to the encoded polypeptide, a vector comprising the nucleic acid molecule, a recombinant non-human organism comprising the nucleic acid molecule, and to methods of producing a triterpenoid hydrocarbon or an intermediate of biofuel using the nucleic acid molecule, polypeptide or recombinant organism.

Ball; Andrew (Bedford Park, AU); Moore; Robert (Bedford Park, AU); Knowles; Gregory (Bedford Park, AU); Qin; Jian (Bedford Park, AU)

2011-10-11

456

Enhancements of rescattered electron yields in above-threshold ionization of molecules  

SciTech Connect

In above-threshold ionization of rare-gas atoms, photoelectron spectra recorded in the 10{sup 13}-10{sup 14} W cm{sup -2} range exhibit enhancements in the rescattering plateaus that do not have a unified theoretical interpretation yet. Here an experimental search for such enhancements is reported in simple molecules with ionization potentials near those of rare-gas atoms such as H{sub 2} and N{sub 2} for argon and O{sub 2} for xenon, and in other molecules such as CO{sub 2} and N{sub 2}O. Only H{sub 2} exhibits the enhancements previously observed in atoms. The H{sub 2} particularity is interpreted in terms of its simpler ion structure and associated ionization paths compared with other molecules.

Cornaggia, C. [CEA IRAMIS, Service Photons Atomes et Molecules, Saclay, Batiment 522, F-91191 Gif-sur-Yvette (France)

2010-11-15

457

Xenon production cross sections at intermediate energies and production rates in small meteoroids based on simulation experiments  

NASA Astrophysics Data System (ADS)

Thin-target production cross sections of xenon isotopes from barium were determined at proton energies of 600 MeV, 800 MeV, 1200 MeV and 2600 MeV using the CERN synchrocyclotron, LANL/Los Alamos and LNS/Saclay accelerators. The data thus obtained are compared with a priori thin-target production cross section calculations using code ALICE. Production cross sections for the neutron induced reactions are estimated theoretically. Together with the cross sections at low energies (<=45 MeV) for the p-induced reactions on barium, determined by us earlier, the present data set provides a basis for evaluating the cosmogenic xenon production rates in extraterrestrial matter. Further, the depth profiles for the production of stable xenon isotopes and 127Xe radionuclide in 5 cm, 15 cm and 25 cm artificial meteoroids, irradiated isotropically with 600 MeV protons, are determined experimentally. These measured depth profiles are compared with theoretical estimates of the xenon production rates from barium in artificial meteoroids, calculated by folding depth dependent spectra of primary protons, secondary protons and neutrons with the thin-target excitation functions for the underlying proton and neutron induced reactions. The production rates thus obtained are compared with theoretical estimates using the depth profiles of well studied radionuclide production in meteoroids of various sizes. The measured xenon production ratios in the thick targets isotropically irradiated with 600 MeV protons and the calculated xenon production ratios in artificial meteoroids irradiated with realistic GCR energy spectrum are compared with those deduced from meteorite analysis and are found to be significantly different. The possible reasons for the discrepancy are explored. The refinements that are still necessary to accurately estimate xenon production rates in extraterrestrial material are discussed.

Mathew, K. J.; Rao, M. N.; Weber, H. W.; Herpers, U.; Michel, R.

1994-12-01

458

CHLORINE DIOXIDE: DRINKING WATER ISSUES  

EPA Science Inventory

Evansville has working in conjunction with Olin Corporation in evaluating two alternative chlorine dioxide generation and application techniques. s a result of these investigations, combined methodologies have been developed that significantly reduce finished water oxychlorine re...

459

Voltammetric Membrane Chlorine Dioxide Electrode.  

National Technical Information Service (NTIS)

A voltammetric membrane electrode system has been modified and applied to the in situ measurement of chlorine dioxide. The electrode system consisted of a gold cathode, a silver/silver chloride reference electrode, and a gold counter electrode. Different ...

R. Dormond-Herrera K. H. Mancy

1980-01-01

460

METHOD OF MAKING PLUTONIUM DIOXIDE  

DOEpatents

A process is presented For converting both trivalent and tetravalent plutonium oxalate to substantially pure plutonium dioxide. The plutonium oxalate is carefully dried in the temperature range of 130 to300DEC by raising the temperature gnadually throughout this range. The temperature is then raised to 600 C in the period of about 0.3 of an hour and held at this level for about the same length of time to obtain the plutonium dioxide.

Garner, C.S.

1959-01-13