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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

Photoionization of atoms and molecules. [of hydrogen, helium, and xenon  

NASA Technical Reports Server (NTRS)

A literature review on the present state of knowledge in photoionization is presented. Various experimental techniques that have been developed to study photoionization, such as fluorescence and photoelectron spectroscopy, mass spectroscopy, are examined. Various atoms and molecules were chosen to illustrate these techniques, specifically helium and xenon atoms and hydrogen molecules. Specialized photoionization such as in positive and negative ions, excited states, and free radicals is also treated. Absorption cross sections and ionization potentials are also discussed.

Samson, J. A. R.

1976-01-01

3

Toward Molecular Mechanism of Xenon Anesthesia: A Link to Studies of Xenon Complexes with Small Aromatic Molecules.  

PubMed

The present study illustrates the steps toward understanding molecular mechanism of xenon anesthesia by focusing on a link to the structures and spectra of intermolecular complexes of xenon with small aromatic molecules. A primary cause of xenon anesthesia is attributed to inhibition of N-methyl-d-aspartate (NMDA) receptors by an unknown mechanism. Following the results of quantum mechanics/molecular mechanics (QM/MM) and molecular dynamics (MD) calculations we report plausible xenon action sites in the ligand binding domain of the NMDA receptor, which are due to interaction of xenon atoms with aromatic amino-acid residues. We rely in these calculations on computational protocols adjusted in combined experimental and theoretical studies of intermolecular complexes of xenon with phenol. Successful reproduction of vibrational shifts in molecular species upon complexation with xenon measured in low-temperature matrices allowed us to select a proper functional form in density functional theory (DFT) approach for use in QM subsystems, as well as to calibrate force field parameters for MD simulations. The results of molecular modeling show that xenon atoms can compete with agonists for a place in the corresponding protein cavity, thus indicating their active role in anesthetic action. PMID:25285819

Andrijchenko, Natalya N; Ermilov, Alexander Yu; Khriachtchev, Leonid; Räsänen, Markku; Nemukhin, Alexander V

2014-10-15

4

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

5

Xenon  

NASA Astrophysics Data System (ADS)

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 in dual (liquid/gas) phase, to detect simultaneously the ionization, through secondary scintillation in the gas, and primary scintillation in the liquid produced by low energy recoils. We review some of the results from the prototype XENON3 detector and briefly discuss about the status of current XENON10 at Gran Sasso Laboratory in Italy.

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

2007-11-01

6

Carbon Dioxide Capture with the Ozone-like Polynitrogen Molecule Li3N3.  

PubMed

In a very recent article (Chem.-Eur. J. 2014, 20, 6636), Olson et al. performed a theoretical study of the low-lying isomers of Li3N3 and found that two of the most stable structures show a novel N3(3-) molecular motif, which possesses structural and chemical bonding features similar to ozone. We explore a first application of these new Li3N3 species as a captor of carbon dioxide. Our results conclude that this is a very exothermic and exoergic process (the capture of one and two carbon dioxide molecules on Li3N3 releases, respectively, 42 and 70 kcal mol(-1) in relative free energy values evaluated at the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ level of theory), which apparently occurs without any energy barrier but requires a nonlinear N3(3-) molecular motif. PMID:25469566

Torrent-Sucarrat, Miquel; Varandas, António J C

2014-12-26

7

Development of a functionalized Xenon biosensor  

SciTech Connect

NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of remote amplified detection. Here we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of functionalized xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

Spence, Megan M.; Ruiz, E. Janette; Rubin, Seth M.; Lowery, Thomas J.; Winssinger, Nicolas; Schultz, Peter G.; Wemmer, David E.; Pines, Alexander

2004-03-25

8

Silicium dioxide nanoparticles as carriers for photoactivatable CO-releasing molecules (PhotoCORMs).  

PubMed

Silicium dioxide nanoparticles of about 20 nm diameter containing azido groups at the surface were prepared by emulsion copolymerization of trimethoxymethylsilane and (3-azidopropyl)triethoxysilane and studied by transmission electron microscopy (TEM). A photoactivatable CO-releasing molecule (PhotoCORM) based on [Mn(CO)(3)(tpm)](+) (tpm = tris(pyrazolyl)methane) containing an alkyne-functionalized tpm ligand was covalently linked to the silicium dioxide nanoparticles via the copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC "click" reaction). The surface functionalization of the particles with azido groups and manganese CORMs was analyzed by UV-vis, IR, (1)H and (13)C CP-MAS NMR spectroscopies as well as energy-dispersive X-ray spectroscopy (EDX). The myoglobin assay was used to demonstrate that the CORM-functionalized nanoparticles have photoinducible CO-release properties very similar to the free complex. In the future, such functionalized silicium dioxide nanoparticles might be utilized as delivery agents for CORMs in solid tumors. PMID:21506524

Dördelmann, Gregor; Pfeiffer, Hendrik; Birkner, Alexander; Schatzschneider, Ulrich

2011-05-16

9

Fixation of carbon dioxide and related small molecules by a bifunctional frustrated pyrazolylborane Lewis pair.  

PubMed

The bifunctional frustrated Lewis pair 1-[bis(pentafluorophenyl)boryl]-3,5-di-tert-butyl-1H-pyrazole (1) was employed for small molecule fixation by reaction with carbon dioxide, paraformaldehyde, tert-butyl isocyanate, tert-butyl isothiocyanate, methyl isothiocyanate and benzonitrile, affording the adducts 3-8 as zwitterionic, bicyclic boraheterocycles. Treatment of 1 with tert-butyl isocyanide gave the isocyanide-borane complex 9, whereas the zwitterionic alkynylborate 10 was formed by C-H bond activation of phenylacetylene. The molecular structures of all products 3-10 were established by X-ray diffraction analyses. DFT calculations at the M06-2X/6-311++G(d,p) level of theory revealed that CO(2) fixation by 1 and formation of the adduct 3 is strongly exothermic and proceeds with a low energy barrier of approximately 7.3 kcal mol(-1) via an intermediate van der Waals complex. PMID:22588317

Theuergarten, Eileen; Schlösser, Janin; Schlüns, Danny; Freytag, Matthias; Daniliuc, Constantin G; Jones, Peter G; Tamm, Matthias

2012-08-14

10

Time stability of liquid xenon photoionization detectors  

Microsoft Academic Search

We measured the collected charges, the energy resolution and their time stability using an ionization chamber filled with liquid xenon doped with trimethylamine (TMA) as photoionization molecules. When liquid xenon was doped with a low concentration of TMA purified at ?110°C, the chamber was operated stably at ?110°C for about 50 h.

H. Okada; T. Doke; K. Hasuike; J. Kikuchi; K. Masuda; M. Shinoda; T. Takahashi; K. Terasawa

1996-01-01

11

Dynamic (hyper)polarizabilities of the sulphur dioxide molecule: Coupled cluster calculations including vibrational corrections  

NASA Astrophysics Data System (ADS)

In this work we report results for dynamical (hyper)polarizabilities of the sulphur dioxide molecule with inclusion of vibrational corrections. The electronic contributions were computed analytically at the single and double coupled cluster level through response theories for the frequencies 0, 0.0239, 0.0428, 0.0656, 0.0720, and 0.0886 hartree. Contributions of the connected triple excitations to the dynamic electronic properties were also estimated through the multiplicative correction scheme. Vibrational corrections were calculated by means of the perturbation theoretical method. The results obtained show that the zero point vibrational correction is very small for all properties studied while the pure vibrational correction is relevant for the dc-Pockels effect, intensity dependent refractive index, and dc-Kerr effect. For these nonlinear optical processes, the pure vibrational corrections represent approximately 75%, 13%, and 6% of the corresponding electronic contributions for the higher frequencies quoted. The results presented for the polarizability are in good agreement with experimental values available in the literature. For the hyperpolarizabilities we have not obtained experimental results with precision sufficient for comparison.

Naves, Emílio S.; Castro, Marcos A.; Fonseca, Tertius L.

2012-01-01

12

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

13

First Results from XENON100  

E-print Network

First Results from XENON100 For the XENON100 Collaboration Rafael F. Lang Columbia University rafael.lang@astro.columbia.edu #12;Rafael F. Lang (Columbia): First Results from XENON100 2 The XENON Università di Bologna Jiao Tong University Shanghai #12;Rafael F. Lang (Columbia): First Results from XENON

Weaver, Harold A. "Hal"

14

Aggregation of amphiphilic molecules in supercritical carbon dioxide: A small angle X-ray scattering study  

SciTech Connect

Highly soluble amphiphilic materials are shown to form aggregates in supercritical CO{sub 2}. The strategy for synthesis of these amphiphilic molecules involves incorporating CO{sub 2}-philic segments that, for this study, are perfluorinated alkyl chains. These CO{sub 2} -philic regions function like the hydrocarbon tails of conventional surfactant molecules used in liquid organic solvents. Synthesis and characterization of three different CO{sub 2} amphiphiles are reported. Subsequent small angle X-ray scattering (SAXS) measurements were used to characterize the aggregation of these materials in supercritical CO{sub 2}. Each of the three amphiphiles studied showed a different type of aggregation behavior. A graft copolymer consisting of a CO{sub 2}-philic backbone and CO{sub 2}-phobic grafts associated into a micellar structure in the presence of water to promote hydrogen bonding. These aggregates contain approximately 600 grafts in the core. The commercially available surfactant perfluoroalkylpoly( ethylene oxide), or F(CF{sub 2}){sub 6-10}CH{sub 2} CH{sub 2}O(CH{sub 2}CH{sub 2}O){sub 3-8}H, forms classic reverse micelle structures having radii of about 84 A under the conditions of high pressure required to solubilize the material. A third amphiphile, the semifluorinated alkane diblock molecule F(CF{sub 2}){sub 10}(CH{sub 2}){sub 10}H, may form small aggregates of at most 4 unimers per aggregate. 41 refs., 10 figs., 1 tab.

Fulton, J.L.; Pfund, D.M. [Pacific Northwest Lab., Richland, WA (United States); McClain, J.B.; Romack, T.J.; Maury, E.E.; Combes, J.R.; Samulski, E.T.; DeSimone, J.M. [Univ. of Noth Carolina, Chapel Hill, NC (United States); Capel, M. [Brookhaven National Lab., Upton, NY (United States)

1995-11-01

15

Chemistry of sulfur-containing molecules on Au( 1 1 1 ): thiophene, sulfur dioxide, and methanethiol adsorption  

NASA Astrophysics Data System (ADS)

The interactions of three sulfur-containing molecules (C 4H 4S, SO 2, CH 3SH) with a clean Au(1 1 1) surface have been studied with a combination of thermal desorption spectroscopy (TDS) and synchrotron-based high-resolution soft X-ray photoelectron spectroscopy. The adsorption and reactivity of the three molecules on Au(1 1 1) are very different. Thiophene adsorbs molecularly on Au(1 1 1) at 100 K and desorbs completely below 330 K without further decomposition. In the submonolayer range, three different adsorption states for chemisorbed thiophene are identified in TDS. It is suggested that thiophene preferably adsorbs on the defect sites at the lowest exposure. After the defect sites are saturated, the change from a flat-lying geometry to a tilted adsorption configuration follows as the exposure increases. Sulfur dioxide also does not decompose on Au(1 1 1). For SO 2 adsorption at 100 K, in addition to the multilayer desorption feature (˜130 K), only one distinct monolayer peak with a tail extending to higher temperature appears in TDS. The desorption temperature difference between the SO 2 monolayer and multilayer is only 15 K, indicating a weak binding between SO 2 and Au. For methanethiol adsorption on Au(1 1 1) at 100 K, three desorption states appear in the submonolayer range for the parent thiol. All of them appear below 300 K. The only desorption products at higher temperature are methane or methyl radicals (˜540 K), and dimethyl disulfide (˜470 K). Apart from the intact methyl thiol molecule, which exists at low temperatures (?150 K), two inequivalent intermediate thiolates, are seen to coexist on Au(1 1 1) in the 150-400 K temperature range, with one of them existing as low as 100 K. Atomic sulfur is present on the surface from 200 to 950 K.

Liu, Gang; Rodriguez, José A.; Dvorak, Joseph; Hrbek, Jan; Jirsak, Tomas

2002-05-01

16

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

17

Is xenon eldest?  

NASA Technical Reports Server (NTRS)

It is well known that the solubility of noble gases in magmas decreases with increasing atomic weight. Xenon, the weightiest of the stable noble gases, is the least soluble atmospheric gas in magma. It is not unreasonable to suppose that the noble gases should have degassed from (or equilibrated with) a bubbling mantle in order of increasing solubility, such that xenon was the most rapidly degassed and helium the least. The apparent relative ages of the famous radiogenic noble gas isotopes agrees, at least qualitatively, with this premise. When atmospheric loss processes are assigned their proper place, several long-standing xenonological puzzles become added evidence for xenon's relative antiquity. Xenon being the afore-mentioned sense the oldest atmospheric gas, will have been most greatly subject to escape, be it impact-driven or EUV-driven. Nonradiogenic xenon's pronounced isotopic fractionation has already been attributed to escape; why it should be more fractionated than krypton would be assigned to xenon's greater atmospheric age. The small atmospheric inventory of xenon relative to the other nonradiogenic noblegases, known as the 'missing xenon' problem, could easily be explained by differential escape. The relatively tiny atmospheric inventories of the radiogenic daughter products of 129 Iodine and 244 Plutonium, both much smaller than would be expected from the inferred abundances of the parents in meteorites, offer a third and fourth data to support the hypothesis that Earth has lost most of its xenon.

Zahnle, K.

1994-01-01

18

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. PMID:19890457

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

2009-01-01

19

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., Garcí­a-Comas, M., López-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

20

The radiation-induced chemistry in solid xenon matrices  

NASA Astrophysics Data System (ADS)

The paper presents an overview of recent studies of the radiation-chemical transformations of guest molecules in solid xenon induced by fast electrons and x-ray irradiation. Specific features of the experimental approach based on the combination of matrix isolation IR and EPR spectroscopy are briefly outlined (with a particular emphasis on monoisotopic and isotopically enriched xenon matrices). The results reveal rich and diverse radiation-induced chemistry in solid xenon, which is considered in the following major aspects: (1) matrix-induced and matrix-assisted transformations of the primary guest radical cations; (2) production and dynamics of hydrogen atoms; (3) formation of xenon hydrides. Finally, preliminary results on the radiation-induced generation of oxygen atoms and ions in solid xenon are presented.

Feldman, V. I.; Kobzarenko, A. V.; Orlov, A. Y.; Sukhov, F. F.

2012-08-01

21

Antiapoptotic activity of argon and xenon  

PubMed Central

Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects. PMID:23907115

Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

2013-01-01

22

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

2001-01-01

23

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

2001-01-01

24

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

25

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

26

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

2001-01-01

27

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

2001-01-01

28

The XENON dark matter experiment  

Microsoft Academic Search

The XENON experiment aims at the direct detection of dark matter in the form\\u000aof WIMPs (Weakly Interacting Massive Particles) via their elastic scattering\\u000aoff Xenon nuclei. With a fiducial mass of 1000 kg of liquid xenon, a\\u000asufficiently low threshold of ~16 keV recoil energy and an un-rejected\\u000abackground rate of 10 events per year, XENON would be sensitive

T. Shutt; E. Aprile; E. Baltz; K. Giboni; P. Majewski; M. Yamashita; K. Ni; U. Oberlack; J. Kwong; K. McDonald; M. Niemack; R. Gaitskell; P. Sorensen; L. Deviveiros; W. Craig

2005-01-01

29

The XENON100 Detector  

E-print Network

XENON100 is a liquid xenon (LXe) time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs). Operated in a low-background shield at the Gran Sasso underground laboratory in Italy, XENON100 has reached the unprecedented background level of $<$0.15 events/day/\\kevr in the energy range below 100 \\kevr in 30 kg of target mass, before electronic/nuclear recoil discrimination. It found no evidence for WIMPs during a dark matter run lasting for 100.9 live days in 2010, excluding with 90% confidence scalar WIMP-nucleon cross sections above 7x10$^{-45}$ cm$^{2}$ at a WIMP mass of 50 GeV/c$^{2}$. A new run started in March 2011, and more than 200 live days of WIMP-search data have been acquired. Results of this second run are expected to be released in summer 2012.

Scovell, P R

2012-01-01

30

The XENON100 Detector  

E-print Network

XENON100 is a liquid xenon (LXe) time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs). Operated in a low-background shield at the Gran Sasso underground laboratory in Italy, XENON100 has reached the unprecedented background level of $<$0.15 events/day/\\kevr in the energy range below 100 \\kevr in 30 kg of target mass, before electronic/nuclear recoil discrimination. It found no evidence for WIMPs during a dark matter run lasting for 100.9 live days in 2010, excluding with 90% confidence scalar WIMP-nucleon cross sections above 7x10$^{-45}$ cm$^{2}$ at a WIMP mass of 50 GeV/c$^{2}$. A new run started in March 2011, and more than 200 live days of WIMP-search data have been acquired. Results of this second run are expected to be released in summer 2012.

P. R. Scovell; XENON100 Collaboration

2012-06-28

31

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

2001-01-01

32

Requirements for Xenon International  

SciTech Connect

This document defines the requirements for the new Xenon International radioxenon system. The output of this project will be a Pacific Northwest National Laboratory (PNNL) developed prototype and a manufacturer-developed production prototype. The two prototypes are intended to be as close to matching as possible; this will be facilitated by overlapping development cycles and open communication between PNNL and the manufacturer.

Hayes, James C.; Ely, James H.; Haas, Derek A.; Harper, Warren W.; Heimbigner, Tom R.; Hubbard, Charles W.; Humble, Paul H.; Madison, Jill C.; Morris, Scott J.; Panisko, Mark E.; Ripplinger, Mike D.; Stewart, Timothy L.

2013-09-26

33

The XENON Dark Matter Experiment  

E-print Network

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 a fiducial mass of 1000 kg of liquid xenon, a sufficiently low threshold of ~16 keV recoil energy and an un-rejected background rate of 10 events per year, XENON would be sensitive to a WIMP-nucleon interaction cross section of 10^(-46) cm^2, for WIMPs with masses above 50 GeV. The 1 tonne scale experiment (XENON1T) will be realized with an array of ten identical 100 kg detector modules (XENON100). The detectors are time projection chambers operated in dual (liquid/gas) phase, to detect simultaneously the ionization, through secondary scintillation in the gas, and primary scintillation in the liquid produced by low energy recoils. The distinct ratio of primary to secondary scintillation for nuclear recoils from WIMPs (or neutrons), and for electron recoils from background, is key to the event-by-event discrimination capability of XENON. A 3kg dual phase detector with light readout provided by an array of 7 photomultipliers is currently being tested, along with other prototypes dedicated to various measurements relevant to the XENON program. We present some of the results obtained to-date and briefly discuss the next step in the phased approach to the XENON experiment, i.e. the development and underground deployment of a 10 kg detector (XENON10) within 2005.

XENON Collaboration; Elena Aprile

2005-02-15

34

Calibrating the Xenon10 Detector with Activated Xenon  

Microsoft Academic Search

Xenon10 is a 15-kg liquid xenon (LXe) detector for the search of dark matter in the form of weakly interacting massive particles (WIMPs). The high scintillation yield of LXe and high light collection efficiency in Xenon10 allow the detection of low-energy nuclear recoils, e.g. from WIMPs elastic scattering, down to 10 keV. The energy calibration is usually performed by using

Kaixuan Ni

2007-01-01

35

NMR of laser-polarized xenon in human?blood  

PubMed Central

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude. The enhanced polarization has allowed advances in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), including polarization transfer to molecules and imaging of lungs and other void spaces. A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization. Described herein is an efficient method for the introduction of laser-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR/MRI signals. Using this method, we have made the first observation of the time-resolved process of xenon penetrating the red blood cells in fresh human blood—the xenon residence time constant in the red blood cells was measured to be 20.4 ± 2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR/MRI is discussed in light of their respective relaxation and partitioning properties. PMID:8917521

Bifone, A.; Song, Y.-Q.; Seydoux, R.; Taylor, R.?E.; Goodson, B.?M.; Pietrass, T.; Budinger, T.?F.; Navon, G.; Pines, A.

1996-01-01

36

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

37

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

38

Degeneracy in cryptophane-xenon complex formation in aqueous solution.  

PubMed

The reversible binding of xenon to cryptophane molecules is currently heavily explored for application as a reporter system in NMR. Herein, for aqueous solution, first evidence of degenerate exchange in this host-guest system is presented based on a novel approach using hyperpolarized (129)Xe. PMID:25516919

Korchak, Sergey; Kilian, Wolfgang; Mitschang, Lorenz

2015-01-15

39

WIMP Searches with Liquid Xenon: the XENON10 Experiment  

Microsoft Academic Search

The XENON experiment searches for Weakly Interacting Massive Particles (WIMPs) with liquid xenon (LXe) as the active target. The detector is a 3-D position sensitive Time Projection Cham- ber optimized to simultaneously measure the ionization and scintillation produced by a recoil event down to energies of 16 keV. The distinct ratio of the two signals for nuclear recoils arising from

Laura Baudis

2005-01-01

40

The XENON dark matter search: status of XENON10  

NASA Astrophysics Data System (ADS)

The XENON experiment searches for dark matter particles called WIMPs using liquid xenon (LXe) as the active target. The detector is a 3D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event of energy as low as 16 keV. The distinct ratio of the two signals for nuclear recoils arising from WIMPs and neutrons and for electron recoils from the dominant gamma-ray background determines its event-by-event discrimination. 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. A phased program will test a 10 kg detector (XENON10) followed by a 100 kg (XENON100) one as unit module for the XENON1T scale experiment. We review the progress of the XENON R & D phase before presenting the status of XENON10. The experiment will be based at the Gran Sasso Underground Laboratory and is expected to start data taking in early 2006.

Aprile, E.; Giboni, K. L.; Kamat, S.; Ni, K.; Singh, B. K.; Yamashita, M.; Gaitskell, R. J.; Sorensen, P.; de Viveiros, L.; Gomez, R.; Oberlack, U.; Shagin, P.; Bolozdynya, A.; Dahl, E.; Kwong, J.; Shutt, T.; Angle, J.; Baudis, L.; Manalaysay, A.; Orboeck, J.; Hasty, R.; Manzur, A.; McKinsey, D.; Bernstein, A.; Madden, N.; Winant, C.; Arneodo, F.; Ferella, A.; Matias Lopes, J. A.; Santos, J.

2006-05-01

41

The XENON dark matter search: status of XENON10  

Microsoft Academic Search

The XENON experiment searches for dark matter particles called WIMPs using liquid xenon (LXe) as the active target. The detector is a 3D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event of energy as low as 16 keV. The distinct ratio of the two signals for nuclear recoils arising from

E. Aprile; K. L. Giboni; S. Kamat; K. Ni; B. K. Singh; M. Yamashita; R. J. Gaitskell; P. Sorensen; L. de Viveiros; R. Gomez; U. Oberlack; P. Shagin; A. Bolozdynya; E. Dahl; J. Kwong; T. Shutt; J. Angle; L. Baudis; A. Manalaysay; J. Orboeck; R. Hasty; A. Manzur; D. McKinsey; A. Bernstein; N. Madden; C. Winant; F. Arneodo; A. Ferella; J. A. Matias Lopes; J. Santos

2006-01-01

42

NMR spectroscopy of xenon sorbed in pentasil zeolites: Silicalites  

SciTech Connect

{sup 129}Xe NMR spectroscopy of xenon sorbed in silicalite samples shows a complex line shape. The authors conclude that there are at least two regions in these samples, one of which is a macroscopic region free of occlusions and the other is a region (or regions) containing occlusions. The authors suggest that these occlusions are residual template molecules from the preparation of the material. Analysis of commercial preparations of silicalite and one prepared in this laboratory indicates that xenon NMR spectroscopy is a simple, straightforward means of examining residual template or other macroscopic occlusions in similar microporous materials.

Tsiao, Chihji; Dybowski, C. (Univ. of Delaware, Newark (USA)); Corbin, D.R. (E.I. du Pont de Nemours and Co., Inc., Wilmington, DE (USA)); Durante, V.; Walker, D. (Sun Refining and Marketing Co., Marcus Hook, PA (USA))

1990-05-17

43

The XENON Dark Matter Experiment  

Microsoft Academic Search

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to measure Xe 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.

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

2011-01-01

44

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

45

Liquid xenon excimer laser  

SciTech Connect

The characteristics of the first excimer laser and the history of its creation are presented. The threshold lasing conditions and the modern theory of active media are considered, and the prospects for the development of excimer lasers operating on condensed inert gases are discussed. It is shown that in experiments on pumping liquid xenon, lasing was obtained simultaneously on excimers of several types, including excimers in liquid and gas phases. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Molchanov, Alexander G [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2003-01-31

46

Shear Thinning in Xenon  

NASA Technical Reports Server (NTRS)

We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

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

2009-01-01

47

A technique for administering xenon gas anesthesia during surgical procedures in mice.  

PubMed

Carrying out invasive procedures in animals requires the administration of anesthesia. Xenon gas offers advantages as an anesthetic agent compared with other agents, such as its protection of the brain and heart from hypoxia-induced damage. The high cost of xenon gas has limited its use as an anesthetic in animal experiments, however. The authors designed and constructed simple boxes for the induction and maintenance of xenon gas and isoflurane anesthesia in small rodents in order to minimize the amount of xenon gas that is wasted. While using their anesthesia delivery system to anesthetize pregnant mice undergoing caesarean sections, they measured the respiratory rates of the anesthetized mice, the survival of the pups and the percentages of oxygen and carbon dioxide within the system to confirm the system's safety. PMID:25333593

Ruder, Arne Mathias; Schmidt, Michaela; Ludiro, Alessia; Riva, Marco A; Gass, Peter

2014-11-01

48

Critical Viscosity of Xenon investigators  

NASA Technical Reports Server (NTRS)

Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

2001-01-01

49

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

50

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

51

Venus, Earth, Xenon  

NASA Astrophysics Data System (ADS)

Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with the chondrites, with Earth, or with none of the above. Modern spacecraft mass spectrometers are at least 100-fold more sensitive to noble gases. Sending such an instrument to Venus may be the last best hope for decrypting what Earth's noble gases have been trying to tell us.

Zahnle, K. J.

2013-12-01

52

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

53

The XENON1T Demonstrator  

NASA Astrophysics Data System (ADS)

We present the results from a facility called the XENON1T Demonstrator at Columbia University, that has been designed and built as a prototype for the XENON1T cryogenic system and TPC. Its primary goal is to demonstrate that the high LXe purity (<1 part per billion O2 equivalent) required for electrons to drift freely over a distance of 1 meter, as in the XENON1T TPC, can be achieved and on a time scale of weeks. The approach adopted in all XENON detectors thus far is that of gas purification with continuous circulation with a diaphragm pump through a heated getter. We show results for high speed recirculation, above 100 slpm, the development of a high voltage feedthrough which is radio pure and the design and application of a prototype TPC to test the purity.

Budnik, Ran; Aprile, Elena; Choi, Bin; Contreras, Hugo; Goetzke, Luke; Lim, Kyungeun; Lang, Rafael; Melgarejo, Antonio; Persiani, Rino; Plante, Guillaume; Rizzo, Alfio; Shagin, Peter

2012-03-01

54

A Decade of Xenon Chemistry  

ERIC Educational Resources Information Center

Presents reactions for the formation of xenon compounds and compounds of the other inert gases. Provides bonding and structure theories for noble gas compounds and speculates on possible applications. (GS)

Moody, G. J.

1974-01-01

55

The XENON100 Dark Matter Experiment  

NASA Astrophysics Data System (ADS)

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

2009-04-01

56

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

57

Barium tagging in solid xenon for the EXO experiment  

NASA Astrophysics Data System (ADS)

Neutrinoless double beta decay experiments are searching for rare decay modes never before observed to uncover the absolute mass of the neutrino, as well as to discover if it is a Majorana fermion. Detection of the daughter nucleus can help provide positive identification of this event over most radioactive backgrounds. The goal of the Enriched Xenon Observatory (EXO) is to measure the rate of 0nubetabeta decay in 136Xe, incorporating 136Ba daughter identification by laser induced fluorescence spectroscopy. Here, we investigate a technique in which the 136Ba daughter is grabbed with a cryogenic probe by freezing it in solid xenon ice, and detected directly in the solid xenon. The absorption and fluorescence spectra of barium in solid xenon were observed for the first time in this work. Identification of the 6s 2 1S0 ? 6s6p 1P 1 transition in both absorption (558 nm) and emission spectra (594 nm) were made. Additional blue absorption and emission lines were observed, but their transitions were not identified. Saturation of the 6s2 1S0 ? 6s6p 1P1 transition was not observed with increased excitation rates using resonance excitation at 558˜nm. From this a limit on the metastable decay rate was deduced to be greater than 104 s-1. Finally a fluorescence spectrum was obtained from a sample with only 20,000 atoms in the laser beam. With potential improvements of 107 in detection efficiency, single barium atom detection seems possible in solid xenon. A fiber probe detector based on a bare single mode fiber was also constructed and tested with fluorescing dye molecules. Successful detection of a few dye molecules in solution at the probe tip was demonstrated.

Mong, Brian

2011-07-01

58

Adsorption of Krypton and Xenon on Evaporated Metal Films  

Microsoft Academic Search

BRENNAN et al.1 quoted our earlier communication2 in connexion with the determination of the effective crosssectional areas of adsorbed xenon molecules, sigma(Xe). However, a numerical error appears in their article. The values 13.8 and 17.2 Å2 were not given in our communication and the value sigma(Kr) = 19.5 Å2 was not used as a reference value. Our communication indicated that

Zlatko Knor; Vladimir Ponec

1964-01-01

59

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

60

The XENON dark matter experiment , E. Aprileb  

E-print Network

The XENON dark matter experiment T. Shutta , E. Aprileb , E. Baltzb , K. Gibonib , P. Majewskib , M Laboratory, Livermore, CA 94550 We report on progress of the XENON collaboration, which is developing a liquid xenon time projection chamber technology for use in a very-large-mass dark matter experiment

McDonald, Kirk

61

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

2001-01-01

62

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

2001-01-01

63

Calibrating the Xenon10 Detector with Activated Xenon  

NASA Astrophysics Data System (ADS)

Xenon10 is a 15-kg liquid xenon (LXe) detector for the search of dark matter in the form of weakly interacting massive particles (WIMPs). The high scintillation yield of LXe and high light collection efficiency in Xenon10 allow the detection of low-energy nuclear recoils, e.g. from WIMPs elastic scattering, down to 10 keV. The energy calibration is usually performed by using external gamma ray sources, such as Co-57 and Cs-137. However, external low-energy gamma rays are not very useful to calibrate the central part of the detector due to their small interaction length (˜mm) in LXe. Calibrations from external high-energy gamma rays are also not accurate due to gamma-ray's non-uniform distributions in the target and non-linearity of LXe scintillation yield for different energies. Here we introduce a new calibration method by using neutron-activated xenon, which emits 164 keV and 236 keV gamma rays uniformly in the target and provides precise energy calibration in every part of the detector. The method also allows the study of position-dependence of the signals, further improving the detector's energy resolution and background rejection capability.

Ni, Kaixuan

2007-04-01

64

Theoretical studies of the decomposition of RDX in liquid xenon  

SciTech Connect

The unimolecular dissociation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in liquid xenon is investigated to determine condensed-phase effects on the N-N bond fission and ring-opening reactions. The dependence of the rate constants on pressure at a fixed temperature is studied using molecular dynamics simulations, and the result is consistent with the experimental finding that the ring-opening channel is suppressed in a condensed-phase environment. The effects of intramolecular vibrational energy redistribution (IVR) and intermolecular energy transfer on reaction rates are also studied by putting a hot RDX molecule in liquid xenon. The reaction rates are calculated using a statistical approach and direct simulations. The statistical rate for the bond fission is 45% larger than the corresponding dynamical one, indicating that the rate of IVR is not faster than that of reaction.

Guo, Y.; Thompson, D.L.

1999-12-02

65

Viscosity of Xenon Examined in Microgravity  

NASA Technical Reports Server (NTRS)

Why does water flow faster than honey? The short answer, that honey has a greater viscosity, merely rephrases the question. The fundamental answer is that viscosity originates in the interactions between a fluid s molecules. These interactions are so complicated that, except for low-density gases, the viscosity of a fluid cannot be accurately predicted. Progress in understanding viscosity has been made by studying moderately dense gases and, more recently, fluids near the critical point. Modern theories predict a universal behavior for all pure fluids near the liquid-vapor critical point, and they relate the increase in viscosity to spontaneous fluctuations in density near this point. The Critical Viscosity of Xenon (CVX) experiment tested these theories with unprecedented precision when it flew aboard the Space Shuttle Discovery (STS-85) in August 1997. Near the critical point, xenon is a billion times more compressible than water, yet it has about the same density. Because the fluid is so "soft," it collapses under its own weight when exposed to the force of Earth s gravity - much like a very soft spring. Because the CVX experiment is conducted in microgravity, it achieves a very uniform fluid density even very close to the critical point. At the heart of the CVX experiment is a novel viscometer built around a small nickel screen. An oscillating electric field forces the screen to oscillate between pairs of electrodes. Viscosity, which dampens the oscillations, can be calculated by measuring the screen motion and the force applied to the screen. So that the fluid s delicate state near the critical point will not be disrupted, the screen oscillations are set to be both slow and small.

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

1999-01-01

66

Preparation of neutron-activated xenon for liquid xenon detector calibration  

Microsoft Academic Search

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×105n\\/s) source, the activities of two gamma ray lines

K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

2007-01-01

67

Bisphosphine dioxides  

DOEpatents

A process for the production of organic bisphosphine dioxides from organic bisphosphonates. The organic bisphosphonate is reacted with a Grignard reagent to give relatively high yields of the organic bisphosphine dioxide.

Moloy, Kenneth G. (Charleston, WV)

1990-01-01

68

Bisphosphine dioxides  

DOEpatents

A process is described for the production of organic bisphosphine dioxides from organic bisphosphonates. The organic bisphosphonate is reacted with a Grignard reagent to give relatively high yields of the organic bisphosphine dioxide.

Moloy, K.G.

1990-02-20

69

Optical and Electron Spin Resonance Studies of Xenon-Nitrogen-Helium Condensates Containing Nitrogen and Oxygen Atoms.  

PubMed

We present the first observations of excimer XeO* molecules in molecular nitrogen films surrounding xenon cores of nanoclusters. Multishell nanoclusters form upon the fast cooling of a helium jet containing small admixtures of nitrogen and xenon by cold helium vapor (T = 1.5 K). Such nanoclusters injected into superfluid helium aggregate into porous impurity-helium condensates. Passage of helium gas with admixtures through a radio frequency discharge allows the storage of high densities of radicals stabilized in impurity-helium condensates. Intense recombination of the radicals occurs during destruction of such condensates and generates excited species observable because of optical emission. Rich spectra of xenon-oxygen complexes have been detected upon destruction of xenon-nitrogen-helium condensates. A xenon environment quenches metastable N((2)D) atoms but has a much weaker effect on the luminescence of N((2)P) atoms. Electron spin resonance spectra of N((4)S) atoms trapped in xenon-nitrogen-helium condensates have been studied. High local concentrations of nitrogen atoms (up to 10(21) cm(-3)) stabilized in xenon-nitrogen nanoclusters have been revealed. PMID:25353614

Boltnev, Roman E; Bykhalo, Igor B; Krushinskaya, Irina N; Pelmenev, Alexander A; Khmelenko, Vladimir V; Mao, Shun; Meraki, Adil; Wilde, Scott C; McColgan, Patrick T; Lee, David M

2014-11-11

70

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

71

Extreme confinement of xenon by cryptophane-111 in the solid state.  

PubMed

Solids that sorb, capture and/or store the heavier noble gases are of interest because of their potential for transformative rare gas separation/production, storage, or recovery technologies. Herein, we report the isolation, crystal structures, and thermal stabilities of a series of xenon and krypton clathrates of (±)-cryptophane-111 (111). One trigonal crystal form, Xe@111?y(solvent), is exceptionally stable, retaining xenon at temperatures of up to about 300?°C. The high kinetic stability is attributable not only to the high xenon affinity and cage-like nature of the host, but also to the crystal packing of the clathrate, wherein each window of the molecular container is blocked by the bridges of adjacent containers, effectively imprisoning the noble gas in the solid state. The results highlight the potential of discrete molecule materials exhibiting intrinsic microcavities or zero-dimensional pores. PMID:25504739

Joseph, Akil I; Lapidus, Saul H; Kane, Christopher M; Holman, K Travis

2015-01-26

72

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.degree. to 30.degree. C.

Markey, John K. (New Haven, CT)

1989-01-01

73

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

74

Hyperpolarized Xenon for NMR and MRI Applications  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2. Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

2012-01-01

75

Results from the XENON100 Dark Matter Search Experiment  

E-print Network

XENON100 is a liquid xenon time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs), which are candidates for the dark matter in our universe, with xenon atoms. Operated in a low-background shield at the Gran Sasso Underground Laboratory in Italy, XENON100 has reached the unprecedented background level of XENON1T detector in Hall B of the Gran Sasso Laboratory will start in late 2012.

Laura Baudis; for the XENON Collaboration

2012-03-07

76

The MEG Liquid Xenon calorimeter  

NASA Astrophysics Data System (ADS)

The MEG experiment at PSI is searching for the lepton-flavour violating decay of the muon into an electron-gamma pair. It is expected to take physics data during the years 2008-2011. From the first three months of data at the end of 2008, we got an upper limit BR(?+ ? e+ + ?) ? 3.0 × 10-11 (90% C.L.). The core of the MEG experiment is an innovative gamma-ray detector, this is a large acceptance and large mass (roughly 2.2 Tons) liquid xenon volume read by photo-multiplier tubes, which is used to measure the photon energy and the position and time of its first conversion. The operation of the detector during the 2008 run will be presented together with several calibration techniques developed to monitor its stability and behaviour during experimental data taking.

Gallucci, G.

2010-04-01

77

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

78

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

79

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commerical Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilator rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

80

The XENON100 Dark Matter Experiment  

SciTech Connect

The XENON100 experiment is searching for WIMPs, which are particles that may consist dark matter. It is located in the underground laboratory of Gran Sasso (LNGS) in Italy at a depth of {approx}3600 m.w.e.. The experiment description, its performance and the expected background based on Monte Carlo simulations and material screening along with the projected sensitivities of the experiment are presented. In addition, a brief description of the upgrade XENON100 detector is given.

Tziaferi, E. [Physics Institute, University of Zuerich, Winterthurerstr. 190, Zuerich (Switzerland)

2010-06-23

81

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.; Marrodán 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

82

Separation of rare gases and chiral molecules by selective binding in porous organic cages  

SciTech Connect

Abstract: The rare gases krypton, xenon, and radon pose both an economic opportunity and a potential environmental hazard. Xenon is used in commercial lighting, medical imaging, and anesthesia, and can sell for $5,000 per kilogram. Radon, by contrast, Is naturally radioactive and the second largest cause of lung cancer, and radioactive xenon, 133Xe, was a major pollutant released In the Fukushima Daiichi Nuclear Power Plant disaster. We describe an organic cage molecule that can capture xenon and radon with unprecedented selectivity, suggesting new technologies for environmental monitoring, removal of pollutants, or the recovery of rare, valuable elements from air.

Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. M.; Armstrong, Jayne A.; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

2014-10-31

83

Stirring Up an Elastic Fluid: Critical Viscosity of Xenon-2 (CVX-2)  

NASA Technical Reports Server (NTRS)

Whipped cream stays in place even when turned upside down. Yet it readily flows through the nozzle of a spray can to reach the dessert plate. This demonstrates the phenomenon of shear thinning that is important to many industrial and physical processes. Paints, film emulsions, and other complex solutions that are highly viscous under normal conditions but become thin and flow easily under shear forces. A simple fluid, such as water, does not exhibit shear thinning under normal conditions. Very close to the liquid-vapor critical point, where the distinction between liquid and vapor disappears, the fluid becomes more complex and is predicted to display shear thinning. At the critical point, xenon atoms interact over long distances in a classical model of cooperative phenomena. Physicists rely on this system to learn how long-range order arises. The Critical Viscosity of Xenon Experiment (CVX-2) will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of fluids. Viscosity originates from the interactions of individual molecules. It is so complicated that, except for the simplest gas, it cannot be calculated accurately from theory. Tests with critical fluids can provide key data, but are limited on Earth because critical fluids are highly compressed by gravity. CVX-2 employs a tiny metal screen vibrating between two electrodes in a bath of critical xenon. The vibrations and how they dampen are used to measure viscosity. CVX flew on STS-85 (1997), where it revealed that, close to the critical point, the xenon is partly elastic: it can 'stretch' as well as flow. For STS-107, the hardware has been enhanced to determine if critical xenon is a shear-thinning fluid.

Berg, Robert F.; Moldover, Michael R.; Zimmerli, Gregory A.; Motil, Susan M. (Technical Monitor)

2002-01-01

84

XENON dark matter searches: Results and the future  

SciTech Connect

XENON100 is a dark matter search experiment looking for elastic WIMP scattering using a 62 kg liquid target. WIMP search data from XENON100 published in 2012 has set the world's strongest limits on WIMP-nucleus spinindependent, elastic scattering. It has also set the strongest limits on WIMP-nucleus spin-dependent scattering considering neutron scattering only, and competitive limits considering proton scattering only. The successor experiment to XENON100, XENON1T, is currently under construction, with commissioning scheduled to begin in 2014. XENON1T's design goal is a 100 fold increase in sensitivity for elastic WIMP searches over XENON100.

Brown, Andrew [Physics Department, Purdue University - 525 Northwestern Ave., West Lafayette, IN 47907 (United States); Collaboration: XENON Collaboration

2014-06-24

85

The Search for Dark Matter with the XENON100 Experiment  

NASA Astrophysics Data System (ADS)

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

2008-11-01

86

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

87

The XENON Dark Matter Experiment: Status of the XENON10 Phase  

Microsoft Academic Search

The XENON experiment searches for Weakly Interacting Massive Particles (WIMPs) with liquid xenon (LXe) as the active target. The detector is a 3-D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event down to energies of 16 keV. The distinct ratio of the two signals for nuclear recoils arising from WIMPs

Maria Elena Monzani

2006-01-01

88

Development of a liquid xenon time projection chamber for the XENON dark matter search  

Microsoft Academic Search

This thesis describes the research conducted for the XENON dark matter direct detection experiment. The tiny energy and small cross-section, from the interaction of dark matter particle on the target, requires a low threshold and sufficient background rejection capability of the detector. The XENON experiment uses dual phase technology to detect scintillation and ionization simultaneously from an event in liquid

Kaixuan Ni

2006-01-01

89

Xenon lighting adjusted to plant requirements  

NASA Technical Reports Server (NTRS)

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 applications in projection and illumination techniques without substantial changes of the spectral quality. Hence, the xenon lamp was the best choice for professional technical purposes where high power at simultaneously good spectral quality of the light was required. However, technical development does not stand still. Between the luminous efficacy of xenon lamps of 25-50 lm/W and the theoretical limit for 'white light' of 250 lm/W is still much room for improvement. The present development mainly favors other lamp types, like metal halide lamps and fluorescent lamps for commercial lighting purposes. The enclosed sections deal with some of the properties of xenon lamps relevant to plant illumination; particularly the spectral aspects, the temporal characteristics of the emission, and finally the economy of xenon lamps will be addressed. Due to radiation exceeding the natural global radiation in both the ultraviolet (UV) and the infrared (IR) regions, filter techniques have to be included into the discussion referring to the requirements of plant illumination. Most of the presented results were obtained by investigations in the GSF phytotron or in the closed Phytocell chambers of the University of Erlangen. As our experiences are restricted to area plant illumination rather than spot lights our discussion will concentrate on low pressure long-arc xenon lamps which are commonly used for such plant illuminations. As the spectral properties of short-arc lamps do not differ much from those of long-arc lamps most of our conclusions will be valid for high pressure xenon lamps too. These lamps often serve as light sources for small sun simulators and for monochromators which are used for action spectroscopy of plant responses.

Koefferlein, M.; Doehring, T.; Payer, Hans D.; Seidlitz, H. K.

1994-01-01

90

Direct Dark Matter Search with XENON100  

E-print Network

The XENON100 experiment is the second phase of the XENON program for the direct detection of the dark matter in the universe. The XENON100 detector is a two-phase Time Projection Chamber filled with 161 kg of ultra pure liquid xenon. The results from 224.6 live days of dark matter search with XENON100 are presented. No evidence for dark matter in the form of WIMPs is found, excluding spin-independent WIMP-nucleon scattering cross sections above 2 $\\times$ 10$^{-45}$ cm$^2$ for a 55 GeV/c$^2$ WIMP at 90% confidence level (C.L.). The most stringent limit is established on the spin-dependent WIMP-neutron interaction for WIMP masses above 6 GeV/c$^2$, with a minimum cross section of 3.5 $\\times$ 10$^{-40}$ cm$^2$ (90% C.L.) for a 45 GeV/c$^2$ WIMP. The same dataset is used to search for axions and axion-like-particles. The best limits to date are set on the axion-electron coupling constant for solar axions, $g_{Ae}$ < 7.7 $\\times$ 10$^{-12}$ (90% C.L.), and for axion-like-particles, $g_{Ae}$ < 1 $\\times$ 10...

Orrigo, S E A

2015-01-01

91

Direct Dark Matter Search with XENON100  

E-print Network

The XENON100 experiment is the second phase of the XENON program for the direct detection of the dark matter in the universe. The XENON100 detector is a two-phase Time Projection Chamber filled with 161 kg of ultra pure liquid xenon. The results from 224.6 live days of dark matter search with XENON100 are presented. No evidence for dark matter in the form of WIMPs is found, excluding spin-independent WIMP-nucleon scattering cross sections above 2 $\\times$ 10$^{-45}$ cm$^2$ for a 55 GeV/c$^2$ WIMP at 90% confidence level (C.L.). The most stringent limit is established on the spin-dependent WIMP-neutron interaction for WIMP masses above 6 GeV/c$^2$, with a minimum cross section of 3.5 $\\times$ 10$^{-40}$ cm$^2$ (90% C.L.) for a 45 GeV/c$^2$ WIMP. The same dataset is used to search for axions and axion-like-particles. The best limits to date are set on the axion-electron coupling constant for solar axions, $g_{Ae}$ < 7.7 $\\times$ 10$^{-12}$ (90% C.L.), and for axion-like-particles, $g_{Ae}$ < 1 $\\times$ 10$^{-12}$ (90% C.L.) for masses between 5 and 10 keV/c$^2$.

S. E. A. Orrigo; for the XENON Collaboration

2015-01-14

92

Detection of small numbers of barium ions implanted in solid xenon for the EXO experiment  

NASA Astrophysics Data System (ADS)

In an effort to discover the yet-unknown absolute masses of neutrinos, the goal of the Enriched Xenon Observatory is to observe neutrinoless double beta decay of 136Xe. Identification of this very rare decay may be difficult even with the best conventional efforts to reduce and reject radioactive background, thus requiring additional background rejection via detection of the daughter 136Ba nucleus. One method of detection is laser-induced fluorescence of the barium atom in solid xenon. Spectra of very small numbers of barium atoms in solid xenon, as few as 3 atoms, are reported for the first time. Demonstration of detection of Ba atoms with large fluorescence efficiencies gives promise for detecting single atoms in the near future. Results from experiments involving implantation of Ba+ ions in solid xenon are discussed. One narrow excitation peak was discovered from ion beam deposition that was not found in neutral deposits. Five new emission lines are found with this same excitation spectrum. Bleaching, annealing, and laser dependence of these lines are studied. The identification of the new Ba species as Ba+ or as a barium molecule is discussed.

Cook, Shon

93

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

94

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 (LXe) as the active target. The detector is a 3-D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event down to energies of 16 keV. The distinct ratio of the two signals for nuclear recoils arising from WIMPs and neutrons and for electron recoils from the dominant gamma-ray background determines its event-by-event discrimination. With 1 ton of LXe distributed in ten identical modules, the proposed XENON1T will achieve a sensitivity more than a factor of thousand beyond current limits. A phased program will test the 10 kg target (XENON10) followed by a 100 kg (XENON100) module. The XENON10 detector was assembled and preliminarily tested at Columbia in January 2006. It was shipped to the Gran Sasso National Laboratory in March and then installed in the underground lab. Testing and calibration runs have been performed through June, while the shielding was constructed: the detector was moved in its final location in the shielded environment in July. The first XENON10 physics run will begin in summer 2006. I present the status of this experiment, along with its expected performance and sensitivity.

Monzani, Maria Elena

2006-10-01

95

Measuring electron lifetime and V0 in Liquid Xenon  

NASA Astrophysics Data System (ADS)

We present performances and results of the Purity Monitoring system developed at Gran Sasso National Laboratories for the XENON experiment. We tested two versions of this device in Liquid Xenon (LXe): one in dedicated chamber, cryostat and gas system, and a smaller one in the XENON3 prototype.

Ferella, A. D.

2007-03-01

96

Xenon NMR measurements of permeability and tortuosity in reservoir rocks  

E-print Network

Xenon NMR measurements of permeability and tortuosity in reservoir rocks Ruopeng Wanga,b , Tina 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

Walsworth, Ronald L.

97

Emission Cross Sections for Neutral Xenon Impacted by Xe+  

E-print Network

Emission Cross Sections for Neutral Xenon Impacted by Xe+ and Xe2+ by Jason D. Sommerville A Thesis Emission cross sections for Neutral Xenon Impacted by Xe+ and Xe2+ by Jason D. Sommerville is hereby for eleven transitions from the 5p5 6p configuration to the 5p5 6s configuration of neutral xenon occur- ring

King, Lyon B.

98

SINGLE ION TRAPPING FOR THE ENRICHED XENON OBSERVATORY  

E-print Network

SINGLE ION TRAPPING FOR THE ENRICHED XENON OBSERVATORY A DISSERTATION SUBMITTED TO THE DEPARTMENT. The Enriched Xenon Observatory for neutrinoless double beta decay (EXO) will search for the rare decays of xenon to determine the absolute value of the neutrino mass. The experiment uses a novel technique

Gratta, Giorgio

99

Development of a liquid xenon time projection chamber for the XENON dark matter search  

NASA Astrophysics Data System (ADS)

This thesis describes the research conducted for the XENON dark matter direct detection experiment. The tiny energy and small cross-section, from the interaction of dark matter particle on the target, requires a low threshold and sufficient background rejection capability of the detector. The XENON experiment uses dual phase technology to detect scintillation and ionization simultaneously from an event in liquid xenon (LXe). The distinct ratio, between scintillation and ionization, for nuclear recoil and electron recoil events provides excellent background rejection potential. The XENON detector is designed to have 3D position sensitivity down to mm scale, which provides additional event information for background rejection. Started in 2002, the XENON project made steady progress in the R&D phase during the past few years. Those include developing sensitive photon detectors in LXe, improving the energy resolution and LXe purity for detecting very low energy events. Two major quantities related to the dark matter detection, the scintillation efficiency and ionization yield of nuclear recoils in LXe, have been established. A prototype dual phase detector (XENON3) has been built and tested extensively in above ground laboratory. The 3D position sensitivity, as well as the background discrimination potential demonstrated from the XENON3 prototype, allows the construction of a 10 kg scale detector (XENON10), to be deployed underground in early 2006. With 99.5% electron recoil rejection efficiency and 16 keVr nuclear recoil energy threshold, XENON10 will be able to probe the WIMP-nucleon cross-section down to 2 x 10-44 cm2 in the supersymmetry parameter space, after one month operation in the Gran Sasso underground laboratory.

Ni, Kaixuan

100

High Resolution Study of Low Lying Correlation Satellites in Xenon  

SciTech Connect

The technique of pulsed field ionization-zero kinetic energy photoelectron spectroscopy, typically applied to the investigation of ionic states of atoms and molecules resulting from single electron excitation, has been used to probe the correlation satellite states of xenon between 23.6-24.7eV. The resulting spectra show the formation of clearly resolved satellite states with intensities of a similar magnitude to that of the 5s5p{sup 6} {sup 2}S{sub 1/2} ionic state. This technique can be extended to other atomic and molecular species to obtain the positions and cross sections for the formation of such states. {copyright} {ital 1998} {ital The American Physical Society}

Evans, M.; Stimson, S.; Ng, C.Y. [Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Hsu, C. [Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

1998-01-01

101

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

102

Response of liquid xenon to low-energy ionizing radiation and its use in the XENON10 dark matter search  

Microsoft Academic Search

This dissertation focuses on developments aimed at improving the effectiveness and understanding of liquid xenon particle detectors in their use in the field of dark matter direct detection. Chapter 3 covers the XENON10 experiment, which searches for evidence of direct interactions between Weakly Interacting Massive Particles (WIMPs) and Xe nuclei. The 3-D position sensitive liquid xenon time projection chamber acquired

Aaron Gosta Manalaysay

2009-01-01

103

Preparation of neutron-activated xenon for liquid xenon detector calibration  

NASA Astrophysics Data System (ADS)

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×10n/s) source, the activities of two gamma ray lines at 164 and 236 keV, from 131mXe and 129mXe metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35, 100 and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

Ni, K.; Hasty, R.; Wongjirad, T. M.; Kastens, L.; Manzur, A.; McKinsey, D. N.

2007-11-01

104

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration  

E-print Network

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

Ni, K; Wongjirad, T M; Kastens, L; Manzur, A; McKinsey, D N

2007-01-01

105

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration  

E-print Network

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

2007-09-27

106

Anticipatory control of xenon in a pressurized water reactor  

SciTech Connect

A method is described for automatically dampening xenon-135 spatial transients in the core of a pressurized water reactor having control rods which regulate reactor power level, comprising the steps of: measuring the neutron flu in the reactor core at a plurality of axially spaced locations on a real-time, on-line basis; repetitively generating from the neutron flux measurements, on a point-by-point basis, signals representative of the current axial distribution of xenon-135, and signals representative of the current rate of change of the axial distribution of xenon-135; generating from the xenon-135 distribution signals and the rate of change of xenon distribution signals, control signals for reducing the xenon transients; and positioning the control rods as a function of the control signals to dampen the xenon-135 spatial transients.

Impink, A.J. Jr.

1987-02-10

107

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

108

The XENON100 Dark Matter Experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to measure Xe 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 Xe gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield. The experiment is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and 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 \\sigma = 2x10^-45 c...

Aprile, E; 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; Undagoitia, T Marrodan; Mei, Y; Fernandez, A J Melgarejo; Ni, K; Oberlack, U; Orrigo, S E A; Pantic, E; Plante, G; Ribeiro, A C C; Santorelli, R; Santos, J M F dos; Schumann, M; Shagin, P; Teymourian, A; Tziaferi, E; Wang, H; Yamashita, M

2011-01-01

109

Xenon fluorides show potential as fluorinating agents  

NASA Technical Reports Server (NTRS)

Xenon fluorides permit the controlled addition of fluorine across an olefinic double bond. They provide a series of fluorinating agents that permit ready separation from the product at a high purity. The reactions may be carried out in the vapor phase.

Chernick, C. L.; Shieh, T. C.; Yang, N. C.

1967-01-01

110

Preliminary Measurements of the Xenon Triple Point  

NASA Astrophysics Data System (ADS)

Ever since the construction and definition of the highly successful International Temperature Scale of 1990 (ITS-90), one severe deficiency of the scale has been recognized, without a reliable remedy. The problem is the fact that the only then available high-quality fixed point between the argon triple point and the water triple point was the mercury triple point, which unfortunately is situated rather closely to the water triple point, thus having an extremely strong influence on the interpolation function of SPRTs in the range. Already before 1990, measurements on possible fixed points better placed in this temperature range have been investigated, such as the triple points of krypton and xenon. However, results have been rather elusive, mainly regarding the rather large melting range of their transition. A turning point was the 2005 paper from the National Research Council (NRC, Canada), where it was established that the relatively high content of krypton was the culprit for the large melting range of the xenon transitions published previously. Indeed, measurements on a xenon sample with very low krypton content produced a very high-quality plateau, of the same level as other ITS-90 fixed points. However, no follow-up measurements have been reported, and thus neither have comparison measurements been reported. Shortly, after the appearance of the NRC paper, Istituto Nazionale di Ricerca Metrologica (INRIM, Italy) acquired a batch of the same high-purity xenon as used by NRC with the aim of preparing a few sealed cells with it and trying to reproduce the NRC results. However, with the start of the Neon Project (Euromet Project 770), the realization of these intentions had to be postponed until now. Last December, three cells of different design have been filled with this high-quality xenon and preliminary results of the measurements on the triple point are reported.

Steur, P. P. M.; Giraudi, D.

2014-04-01

111

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

112

Spectroscopy of Ba and Ba$^+$ deposits in solid xenon for barium tagging in nEXO  

E-print Network

Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba$^+$ deposits is identified with some type of barium hydride molecule. Lower limits for the fluorescence quantum efficiency of the principal Ba emission transition are reported. Under current conditions, an image of $\\le10^4$ Ba atoms can be obtained. Prospects for imaging single Ba atoms in solid xenon are discussed.

B. Mong; S. Cook; T. Walton; C. Chambers; A. Craycraft; C. Benitez-Medina; K. Hall; W. Fairbank Jr.; J. B. Albert; D. J. Auty; P. S. Barbeau; V. Basque; D. Beck; M. Breidenbach; T. Brunner; G. F. Cao; B. Cleveland; M. Coon; T. Daniels; S. J. Daugherty; R. DeVoe; T. Didberidze; J. Dilling; M. J. Dolinski; M. Dunford; L. Fabris; J. Farine; W. Feldmeier; P. Fierlinger; D. Fudenberg; G. Giroux; R. Gornea; K. Graham; G. Gratta; M. Heffner; M. Hughes; X. S. Jiang; T. N. Johnson; S. Johnston; A. Karelin; L. J. Kaufman; R. Killick; T. Koffas; S. Kravitz; R. Krucken; A. Kuchenkov; K. S. Kumar; D. S. Leonard; C. Licciardi; Y. H. Lin; J. Ling; R. MacLellan; M. G. Marino; D. Moore; A. Odian; I. Ostrovskiy; A. Piepke; A. Pocar; F. Retiere; P. C. Rowson; M. P. Rozo; A. Schubert; D. Sinclair; E. Smith; V. Stekhanov; M. Tarka; T. Tolba; K. Twelker; J. -L. Vuilleumier; J. Walton; M. Weber; L. J. Wen; U. Wichoski; L. Yang; Y. -R. Yen; Y. B. Zhao

2014-10-09

113

Spectroscopy of Ba and Ba$^+$ deposits in solid xenon for barium tagging in nEXO  

E-print Network

Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba$^+$ deposits is identified with some type of barium hydride molecule. Lower limits for the fluorescence quantum efficiency of the principal Ba emission transition are reported. Under current conditions, an image of $\\le10^4$ Ba atoms can be obtained. Prospects for imaging single Ba atoms in solid xenon are discussed.

Mong, B; Walton, T; Chambers, C; Craycraft, A; Benitez-Medina, C; Hall, K; Fairbank, W; Albert, J B; Auty, D J; Barbeau, P S; Basque, V; Beck, D; Breidenbach, M; Brunner, T; Cao, G F; Cleveland, B; Coon, M; Daniels, T; Daugherty, S J; DeVoe, R; Didberidze, T; Dilling, J; Dolinski, M J; Dunford, M; Fabris, L; Farine, J; Feldmeier, W; Fierlinger, P; Fudenberg, D; Giroux, G; Gornea, R; Graham, K; Gratta, G; Heffner, M; Hughes, M; Jiang, X S; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Kravitz, S; Krucken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Licciardi, C; Lin, Y H; Ling, J; MacLellan, R; Marino, M G; Moore, D; Odian, A; Ostrovskiy, I; Piepke, A; Pocar, A; Retiere, F; Rowson, P C; Rozo, M P; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Twelker, K; Vuilleumier, J -L; Walton, J; Weber, M; Wen, L J; Wichoski, U; Yang, L; Yen, Y -R; Zhao, Y B

2014-01-01

114

Energy of the quasi-free electron in xenon Xianbo Shi a  

E-print Network

Energy of the quasi-free electron in xenon Xianbo Shi a , Luxi Li a , C.M. Evans a,, G.L. Findley b of trimethylamine and of N,N-dimethylaniline doped into xenon is presented as a function of xenon number density up. These data exhibit a decrease in the xenon induced shift of the dopant ionization energy near the xenon

Findley, Gary L.

115

XENON100 Dark Matter Search: Scintillation Response of Liquid Xenon to Electronic Recoils  

NASA Astrophysics Data System (ADS)

Dark matter is one of the missing pieces necessary to complete the puzzle of the universe. Numerous astrophysical observations at all scales suggest that 23 % of the universe is made of nonluminous, cold, collisionless, nonbaryonic, yet undiscovered dark matter. Weakly Interacting Massive Particles (WIMPs) are the most well-motivated dark matter candidates and significant efforts have been made to search for WIMPs. The XENON100 dark matter experiment is currently the most sensitive experiment in the global race for the first direct detection of WIMP dark matter. XENON100 is a dual-phase (liquid-gas) time projection chamber containing a total of 161 kg of liquid xenon (LXe) with a 62kg WIMP target mass. It has been built with radiopure materials to achieve an ultra-low electromagnetic background and operated at the Laboratori Nazionali del Gran Sasso in Italy. WIMPs are expected to scatter off xenon nuclei in the target volume. Simultaneous measurement of ionization and scintillation produced by nuclear recoils allows for the detection of WIMPs in XENON100. Data from the XENON100 experiment have resulted in the most stringent limits on the spin-independent elastic WIMP-nucleon scattering cross sections for most of the significant WIMP masses. As the experimental precision increases, a better understanding of the scintillation and ionization response of LXe to low energy (< 10 keV) particles is crucial for the interpretation of data from LXe based WIMP searches. A setup has been built and operated at Columbia University to measure the scintillation response of LXe to both electronic and nuclear recoils down to energies of a few keV, in particular for the XENON100 experiment. In this thesis, I present the research carried out in the context of the XENON100 dark matter search experiment. For the theoretical foundation of the XENON100 experiment, the first two chapters are dedicated to the motivation for and detection medium choice of the XENON100 experiment, respectively. A general review about dark matter focusing on WIMPs and their direct detection with liquid noble gas detectors is presented in Chap. 1. LXe as an attractive WIMP detection medium is explained in Chap. 2. The XENON100 detector design, the detector, and its subsystems are detailed in Chap. 3. The calibration of the detector and the characterized detector response used for the discrimination of a WIMP-like signal against background are explained in Chap. 4. In an effort to understand the background, anomalous electronic recoils were studied extensively and are described in Chap. 5. In order to obtain a better understanding of the electronic recoil background of XENON100, including an estimation of the electronic recoil background contribution, as well as to interpret dark matter results such as annual modulation, measurement of the scintillation yield of low-energy electrons in LXe was performed in 2011, with the dedicated setup mentioned above. The results from this measurement are discussed in Chap. 6. Finally, the results for the latest science data from XENON100 to search for WIMPs, comprising 225 live-days taken over 13 months during 2011 and 2012 are explained in Chap. 7.

Lim, Kyungeun Elizabeth

116

A cryogenic distillation column for the XENON1T experiment  

NASA Astrophysics Data System (ADS)

The XENON collaboration aims for the direct detection of cold dark matter in form of weakly interacting massive particles (WIMPs). A dual phase time projection chamber filled with liquid xenon is used to detect the WIMP-nucleon interaction. For the next generation experiment XENON1T with an active target mass of 1 ton of xenon, a new distillation column to remove krypton out of xenon to a concentration of < 5 × 10?13 (0.5 ppt) natural krypton in xenon is designed and tested at the Institut für Kernphysik, Universitat Munster. The experimental setup together with two diagnostic tools is presented, as well as one stability test of a 11 hour distillation run at the designed flowrate of 3 kg per hour.

Rosendahl, S.; Brown, E.; Cristescu, I.; Fieguth, A.; Huhmann, C.; Murra, M.; Weinheimer, C.

2014-11-01

117

The Large Underground Xenon (LUX) Experiment  

E-print Network

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 $2\\times 10^{-46}$ cm$^{2}$, equivalent to $\\sim$1 event/100 kg/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.

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

2012-11-21

118

Recovering Residual Xenon Propellant for an Ion Propulsion System  

NASA Technical Reports Server (NTRS)

Future nuclear-powered Ion-Propulsion- System-propelled spacecraft such as Jupiter Icy Moon Orbiter (JIMO) will carry more than 10,000 kg of xenon propellant. Typically, a small percentage of this propellant cannot be used towards the end of the mission because of the pressure drop requirements for maintaining flow. For large missions such as JIMO, this could easily translate to over 250 kg of unusable xenon. A proposed system, the Xenon Recovery System (XRS), for recovering almost all of the xenon remaining in the tank, would include a cryopump in the form of a condenser/evaporator that would be alternatively cooled by a radiator, then heated electrically. When the pressure of the xenon in the tank falls below 0.7 MPa (100 psia), the previously isolated XRS will be brought online and the gas from the tank would enter the cryopump that is initially cooled to a temperature below saturation temperature of xenon. This causes xenon liquefaction and further cryopumping from the tank till the cryopump is full of liquid xenon. At this point, the cryopump is heated electrically by small heaters (70 to 80 W) to evaporate the liquid that is collected as high-pressure gas (<7 MPa; 1,000 psia) in an intermediate accumulator. Check valves between the tank and the XRS prevent the reverse flow of xenon during the heating cycle. The accumulator serves as the high-pressure source of xenon gas to the Xenon Feed System (XFS) downstream of the XRS. This cycle is repeated till almost all the xenon is recovered. Currently, this system is being baselined for JIMO.

Ganapathi, Gani; Skakkottai, P.; wu, Jiunn Jeng

2006-01-01

119

Xenon recirculation-purification with a heat exchanger  

Microsoft Academic Search

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-01-01

120

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

121

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

122

Liquid xenon detectors for particle physics and astrophysics  

NASA Astrophysics Data System (ADS)

This article reviews the progress made over the last 20years in the development and applications of liquid xenon detectors in particle physics, astrophysics, and medical imaging experiments. A summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information is first provided. After an introduction of the different type of liquid xenon detectors, a review of past, current, and future experiments using liquid xenon to search for rare processes and to image radiation in space and in medicine is given. Each application is introduced with a survey of the underlying scientific motivation and experimental requirements before reviewing the basic characteristics and expected performance of each experiment. Within this decade it appears likely that large volume liquid xenon detectors operated in different modes will contribute to answering some of the most fundamental questions in particle physics, astrophysics, and cosmology, fulfilling the most demanding detection challenges. From detectors based solely on liquid xenon (LXe) scintillation, such as in the MEG experiment for the search of the rare “ ??e? ” decay, currently the largest liquid xenon detector in operation, and in the XMASS experiment for dark matter detection, to the class of time projection chambers which exploit both scintillation and ionization of LXe, such as in the XENON dark matter search experiment and in the Enriched Xenon Observatory for neutrinoless double beta decay, unrivaled performance and important contributions to physics in the next few years are anticipated.

Aprile, E.; Doke, T.

2010-07-01

123

Status of the XENON Direct Dark Matter Detection Experiment  

SciTech Connect

The XENON Collaboration is developing a dark matter detector using liquid xenon (LXe) as the target medium for detecting weakly interacting massive particles (WIMPs). The goal of the collaboration is to operate an array of LXe time projection chambers (TPCs) with 1000 times greater sensitivity to WIMPs than current direct dark matter detection experiments. Recent measurements by members of the XENON collaboration have demonstrated the promise of the LXe TPC approach, particularly measurements of the scintillation efficiency and charge response of LXe to nuclear recoils. The collaboration plans to operate a 10 kg fiducial volume prototype, XENON10, underground in the spring of 2006.

Hasty, Richard [Yale University, New Haven, CT (United States)

2006-07-11

124

Status of the XENON Direct Dark Matter Detection Experiment  

NASA Astrophysics Data System (ADS)

The XENON Collaboration is developing a dark matter detector using liquid xenon (LXe) as the target medium for detecting weakly interacting massive particles (WIMPs). The goal of the collaboration is to operate an array of LXe time projection chambers (TPCs) with 1000 times greater sensitivity to WIMPs than current direct dark matter detection experiments. Recent measurements by members of the XENON collaboration have demonstrated the promise of the LXe TPC approach, particularly measurements of the scintillation efficiency and charge response of LXe to nuclear recoils. The collaboration plans to operate a 10 kg fiducial volume prototype, XENON10, underground in the spring of 2006.

Hasty, Richard

2006-07-01

125

Liquid Xenon Detectors for Particle Physics and Astrophysics  

E-print Network

This article reviews the progress made over the last 20 years in the development and applications of liquid xenon detectors in particle physics, astrophysics and medical imaging experiments. We begin with a summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information. After a brief introduction of the different type of liquid xenon detectors, we continue with a review of past, current and future experiments using liquid xenon to search for rare processes and to image radiation in space and in medicine. We will introduce each application with a brief survey of the underlying scientific motivation and experimental requirements, before reviewing the basic characteristics and expected performance of each experiment. Within this decade it appears likely that large volume liquid xenon detectors operated in different modes will contribute to answering some of the most fundamental questions in particle physics, astrophysics and cosmology, fulfilling the most demanding detection challenges. From experiments like MEG, currently the largest liquid xenon scintillation detector in operation, dedicated to the rare mu -> e + gamma decay, to the future XMASS which also exploits only liquid xenon scintillation to address an ambitious program of rare event searches, to the class of time projection chambers like XENON and EXO which exploit both scintillation and ionization of liquid xenon for dark matter and neutrinoless double beta decay, respectively, we anticipate unrivaled performance and important contributions to physics in the next few years.

E. Aprile; T. Doke

2009-10-26

126

Liquid xenon detectors for particle physics and astrophysics  

SciTech Connect

This article reviews the progress made over the last 20 years in the development and applications of liquid xenon detectors in particle physics, astrophysics, and medical imaging experiments. A summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information is first provided. After an introduction of the different type of liquid xenon detectors, a review of past, current, and future experiments using liquid xenon to search for rare processes and to image radiation in space and in medicine is given. Each application is introduced with a survey of the underlying scientific motivation and experimental requirements before reviewing the basic characteristics and expected performance of each experiment. Within this decade it appears likely that large volume liquid xenon detectors operated in different modes will contribute to answering some of the most fundamental questions in particle physics, astrophysics, and cosmology, fulfilling the most demanding detection challenges. From detectors based solely on liquid xenon (LXe) scintillation, such as in the MEG experiment for the search of the rare ''{mu}{yields}e{gamma}'' decay, currently the largest liquid xenon detector in operation, and in the XMASS experiment for dark matter detection, to the class of time projection chambers which exploit both scintillation and ionization of LXe, such as in the XENON dark matter search experiment and in the Enriched Xenon Observatory for neutrinoless double beta decay, unrivaled performance and important contributions to physics in the next few years are anticipated.

Aprile, E.; Doke, T. [Department of Physics, Columbia University, New York, New York 10027 (United States); Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan)

2010-07-15

127

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

128

A photochemical answer to the 'xenon paradox'  

NASA Astrophysics Data System (ADS)

Xenon is depleted by one order of magnitude relative to other volatile elements when normalized to the chondritic composition. Furthermore, atmospheric xenon is far more enriched in the heavy isotopes relatively to chondritic and solar compositions (3-4%.amu-1) than atmospheric krypton (< 1%.amu-1). This discrepancy, known as the 'xenon paradox', has led to sophisticated models of atmospheric evolution coupled with mantle geodynamics (Pepin, 1991; Tolstikhin and Marty, 1998) and cometary contributions (Dauphas, 2003; Owen et al., 1992) that could explain terrestrial noble gas patterns under ad hoc conditions during the building stages of the Earth, no more than ~200 Ma following the beginning of solar system formation. Yet, xenon having an isotopic composition intermediate between the atmospheric and the chondritic ones has been recently documented in Archean (?3 Ga-old) sedimentary rocks (Pujol et al., 2011), suggesting that isotopic fractionation of Xe occurred over a much longer period of time than previously thought, during the Hadean and the Archean eons. In that case, assuming a Rayleigh type isotope evolution for atmospheric Xe requires an enrichment fractionation factor of 1.3% in heavy isotopes for Xe remaining in the atmosphere. This is clearly within the range of values observed in laboratory experiments aimed at trapping and fractionating Xe isotopes in solids, which is only effective upon ionization (Marrocchi et al., 2011; Kuga et al., 2012). We report here a possibility for explaining the 'xenon paradox' through interaction of the Hadean/Archean atmosphere with EUV light from the young Sun. By using a new photochemical model, we have found out that atmospheric Xe depletion and enrichment in heavy Xe isotopes could be achieved by EUV photoionization deep enough in the atmosphere to allow the preferential implantation of the heavier Xe isotopes in organic aerosols, the formation of which is itself triggered by UV photochemistry. Most of the ionized Xe would have escaped from the atmosphere into space by hydrodynamic escape (Zahnle, 2011). We have established that this mechanism specifically affected Xe and was particularly effective during the Hadean/Archean times, since the irradiation flux was expected to be orders of magnitude higher than today (Ribas et al., 2010). Dauphas (2003), Icarus 165, 326-339. Kuga et al. (2012), #2347 Goldschmidt 2012 Marrocchi et al. (2011), GCA 75, 6255-6266. Owen et al. (1992), Nature 358, 43-46. Pepin (1991), Icarus 92, 1-79. Pujol et al. (2011), Earth Planet. Sci. Lett. 308, 298-306. Ribas et al. (2010), Astrophys. J. 714, 384-395. Srinivasan, (1976), Earth Planet. Sci. Lett. 31, 129-141. Tolstikhin and Marty (1998), Chem. Geol. 147, 27-52. Zahnle (2011), #2241 Goldschmidt 2011

Hébrard; Marty, B.

2012-12-01

129

Let's Make Molecules  

NSDL National Science Digital Library

In this activity, learners use gumdrops and toothpicks to model the composition and molecular structure of three greenhouse gases: carbon dioxide (CO2), water vapor (H2O) and methane (CH4). Learners explore how greenhouse gases are released into the atmosphere as well as how these gases contribute to global climate change. This activity guide includes an extension activity in which learners move their bodies to model the arrangement of atoms in a methane molecule.

Sciencenter

2010-01-01

130

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

131

Dendronized cryptophanes as water-soluble xenon hosts for (129)Xe magnetic resonance imaging.  

PubMed

Cryptophane cages are very promising for (129)Xe-MRI. These molecular cages are extremely hydrophobic, which currently limits their use for diagnostic applications. To overcome this, the synthesis of water-soluble dendronized cryptophanes with surface groups for further functionalization is reported here. These molecules retained all the "core properties of cryptophane" that are crucial for biosensor applications as analyzed by Hyper-CEST imaging and spectroscopy. This approach is promising for developing new generations of xenon-cryptophane-based biosensors. PMID:25152959

Tyagi, Rahul; Witte, Christopher; Haag, Rainer; Schröder, Leif

2014-09-01

132

Blended polymer materials extractable with supercritical carbon dioxide  

Microsoft Academic Search

Supercritical carbon dioxide is drawing more and more attention because of its unique solvent properties along with being environmentally friendly. Historically most of the commercial interests of supercritical carbon dioxide extraction are in the food industry, pharmaceutical industry, environmental preservation and polymer processing. Recently attention has shifted from the extraction of relatively simple molecules to more complex systems with a

Mei Cai

1999-01-01

133

Reactions of tetracycline antibiotics with chlorine dioxide and free chlorine  

E-print Network

Reactions of tetracycline antibiotics with chlorine dioxide and free chlorine Pei Wang a,b , Yi such as chlorine dioxide (ClO2) and free available chlorine (FAC) have not been studied in depth and are the focus to (hydr)oxylation and breakage of TC molecules, while oxidation of TCs by FAC leads to chlorinated

Huang, Ching-Hua

134

The XENON1T Dark Matter Search Experiment  

E-print Network

The worldwide race towards direct dark matter detection in the form of Weakly Interacting Massive Particles (WIMPs) has been dramatically accelerated by the remarkable progress and evolution of liquid xenon time projection chambers (LXeTPCs). With a realistic discovery potential, XENON100 has already reached a sensitivity of $7\\times10^{-45}\\,\

Aprile, Elena

2012-01-01

135

Status of the XENON Direct Dark Matter Detection Experiment  

Microsoft Academic Search

The XENON Collaboration is developing a dark matter detector using liquid xenon (LXe) as the target medium for detecting weakly interacting massive particles (WIMPs). The goal of the collaboration is to operate an array of LXe time projection chambers (TPCs) with 1000 times greater sensitivity to WIMPs than current direct dark matter detection experiments. Recent measurements by members of the

Richard Hasty

2006-01-01

136

Status of the XENON Direct Dark Matter Detection Experiment  

Microsoft Academic Search

The XENON collaboration is developing a dark matter detector using liquid xenon (LXe) as the target medium for detecting Weakly Interacting Massive Particles (WIMPs). The goal of the collaboration is to operate an array of LXe time projection chambers (TPCs) with 1000 times greater sensitivity to WIMPs than current direct dark matter detection experiments. Recent measurements by members of the

Richard Hasty

2006-01-01

137

Experimental study of a liquid Xenon PET prototype module  

E-print Network

A detector using liquid Xenon in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the liquid Xenon properties. It does feature a promising insensitive to any parallax effect. This work reports on the performances of the first LXe prototype module, equipped with a position sensitive PMT operating in the VUV range (178 nm).

Gallin-Martel, M L; Mayet, F; Ballon, J; Barbier, G; Barnoux, C; Berger, J; Bondoux, D; Bourrion, O; Collot, J; Dzahini, D; Foglio, R; Gallin-Martel, L; Garrigue, A; Jan, S; Petit, P; Stassi, P; Vezzu, F; Tournefier, E

2006-01-01

138

The XENON1T Dark Matter Search Experiment  

E-print Network

The worldwide race towards direct dark matter detection in the form of Weakly Interacting Massive Particles (WIMPs) has been dramatically accelerated by the remarkable progress and evolution of liquid xenon time projection chambers (LXeTPCs). With a realistic discovery potential, XENON100 has already reached a sensitivity of $7\\times10^{-45}\\,\

Elena Aprile; XENON1T collaboration

2012-06-27

139

Liquid xenon detectors for particle physics and astrophysics  

Microsoft Academic Search

This article reviews the progress made over the last 20years in the development and applications of liquid xenon detectors in particle physics, astrophysics, and medical imaging experiments. A summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information is first provided. After an introduction of the different type

E. Aprile; T. Doke

2010-01-01

140

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. PMID:23758970

2013-01-01

141

Design and Performance of the XENON10 Dark Matter Experiment  

E-print Network

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously.

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; Orlandi, D; Plante, G; Santorelli, R; Santos, J M F dos; Shagin, P; Shutt, T; Sorensen, P; Schulte, S; Tatananni, E; Winant, C; Yamashita, M

2010-01-01

142

Design and performance of the XENON10 dark matter experiment  

NASA Astrophysics Data System (ADS)

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso Underground Laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulation data. The results on the detector's energy threshold, position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and low background rate achieved.

Aprile, E.; Angle, J.; 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.; Orlandi, D.; Plante, G.; Santorelli, R.; dos Santos, J. M. F.; Shagin, P.; Shutt, T.; Sorensen, P.; Schulte, S.; Tatananni, E.; Winant, C.; Yamashita, M.

2011-04-01

143

Low-temperature electrical discharge through solid xenon  

NASA Astrophysics Data System (ADS)

A uniform self-sustained electrical discharge through solid xenon is realized and studied. The multiplication of electrons proceeds in the noble gas above the xenon crystal interface, whereas a positive feedback is realized on account of multiple exciton formation by excess electrons drifting through the crystal: molecular excitons emit VUV photons which knock out secondary electrons from photosensitive cathode. The discharge is stimulated by a short electrical spark along the sample axes. The electrical properties of the discharge and the electroluminescence spectra of solid xenon in the UV and visible are studied. Electrical discharge in solid xenon proves to be an effective source of UV radiation and a convenient tool for studying processes involving excitons and electrons in solid xenon at high pressures.

Gordon, E. B.; Matyushenko, V. I.; Sizov, V. D.; Smirnov, B. M.

2008-11-01

144

Xenon-Ion Drilling of Tungsten Films  

NASA Technical Reports Server (NTRS)

High-velocity xenon ions used to drill holes of controlled size and distribution through tungsten layer that sheaths surface of controlled-porosity dispenser cathode of traveling wave-tube electron emitter. Controlled-porosity dispenser cathode employs barium/calcium/ aluminum oxide mixture that migrates through pores in cathode surface, thus coating it and reducing its work function. Rapid, precise drilling technique applied to films of other metals and used in other applications where micron-scale holes required. Method requires only few hours, as opposed to tens of hours by prior methods.

Garner, C. E.

1986-01-01

145

Xenon and other noble gases in shergottites  

NASA Astrophysics Data System (ADS)

The isotopic composition of the xenon component trapped in EETA 79001's lithologies B and C has been determined, and other noble gases were measured in some samples. The Xe component was found to have light isotope ratios indistinguishable from those of the terrestrial atmosphere. The trapped component has a Xe-129/Xe-132 ratio of about 2.4, and is enhanced in Xe-134 and Xe-136 relative to the terrestrial atmosphere or the average carbonaceous chondrite. Similarities between values for Ar-40/Ar-36, Xe-129/Xe-132, and N-15/N-14 and the corresponding Martian atmospheric values suggest Martian origin of the trapped gases.

Swindle, T. D.; Caffee, M. W.; Hohenberg, C. M.

1986-06-01

146

High fidelity equation of state for xenon : integrating experiments and first principles simulations in developing a wide-range equation of state model for a fifth-row element.  

SciTech Connect

The noble gas xenon is a particularly interesting element. At standard pressure xenon is an fcc solid which melts at 161 K and then boils at 165 K, thus displaying a rather narrow liquid range on the phase diagram. On the other hand, under pressure the melting point is significantly higher: 3000 K at 30 GPa. Under shock compression, electronic excitations become important at 40 GPa. Finally, xenon forms stable molecules with fluorine (XeF{sub 2}) suggesting that the electronic structure is significantly more complex than expected for a noble gas. With these reasons in mind, we studied the xenon Hugoniot using DFT/QMD and validated the simulations with multi-Mbar shock compression experiments. The results show that existing equation of state models lack fidelity and so we developed a wide-range free-energy based equation of state using experimental data and results from first-principles simulations.

Flicker, Dawn G.; Root, Seth; Mattsson, Thomas Kjell Rene; Magyar, Rudolph J.; Carpenter, John H.

2010-05-01

147

Xenon NMR of phase biaxiality in liquid crystals.  

PubMed

Biaxial thermotropic nematic liquid crystals would be of great importance in liquid crystal display technology. Less than a decade ago, such liquid crystals were suggested. The biaxiality of the phases was confirmed using (2)H NMR spectroscopy of deuterated probe molecules. The spectra were collected from a sample rotating around an axis perpendicular to the external magnetic field, resulting in a two-dimensional powder pattern. We have proposed an alternate technique that is based on the second order quadrupole shift detectable in (131)Xe NMR spectra of dissolved xenon. The method has many advantages, such as the NMR spectra are taken from a static sample and the (131)Xe quadrupole coupling tensor is extremely sensitive to the symmetry of the phase. In the present study, we report results obtained on a 600-MHz NMR spectrometer. Together with the data of our earlier study, they confirm that the asymmetry parameter of the (131)Xe quadrupole coupling tensor in the nematic phase of a ferroelectric liquid crystal is 0.85 and in the smectic A phase ca 0.62, indicating significant phase biaxiality. PMID:24771455

Jokisaari, Jukka; Zhu, Jianfeng

2014-10-01

148

Radio detection of interstellar sulfur dioxide  

NASA Technical Reports Server (NTRS)

Interstellar sulfur dioxide (SO2) has been detected in emission from the direction of the Orion Nebula molecular cloud and from Sgr B2. SO2 is the heaviest interstellar molecule detected to date, and the only nonlinear triatomic molecule which does not contain hydrogen. The remarkable Orion emission profiles suggest that two components are supporting the SO2 emission: a dense circumstellar-type envelope, which may be in maser emission, and a warm galactic cloud component.

Snyder, L. E.; Hollis, J. M.; Ulich, B. L.; Lovas, F. J.; Johnson, D. R.; Buhl, D.

1975-01-01

149

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1  

E-print Network

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1 C.-H. Tseng,1,2 G. P and diffusion of laser-polarized xenon (129 Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid

Walsworth, Ronald L.

150

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

151

Influence of Xenon on Protein Hydration as measured by a Microwave Absorption Technique  

Microsoft Academic Search

INVESTIGATIONS into the transport mechanisms of xenon during xenon anæsthesia1,2 showed that this noble gas associates reversibly with the blood proteins3. Standard (PVT) uptake measurements showed that for human hæmoglobin in aqueous solution (at 20° C; 1 atm. xenon pressure pH 7) 1.8 moles of xenon associate per mole of hæmoglobin4.

B. P. Schoenborn; R. M. Featherstone

1964-01-01

152

Gallery of Greenhouse Gas Molecules  

NSDL National Science Digital Library

This static visualization from Global Warming Art depicts the chemical characteristics of eight greenhouse gas molecules - carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), water (H2O), ozone (O3), sulfur hexafluoride (SF6), dichlorodifluoromethane (CFC-12), and trichlorofluoromethane (CFC-11).

Ben Mills

153

Xenon ion propulsion for orbit transfer  

NASA Technical Reports Server (NTRS)

For more than 30 years, NASA has conducted an ion propulsion program which has resulted in several experimental space flight demonstrations and the development of many supporting technologies. Technologies appropriate for geosynchronous stationkeeping, earth-orbit transfer missions, and interplanetary missions are defined and evaluated. The status of critical ion propulsion system elements is reviewed. Electron bombardment ion thrusters for primary propulsion have evolved to operate on xenon in the 5 to 10 kW power range. Thruster efficiencies of 0.7 and specific impulse values of 4000 s were documented. The baseline thruster currently under development by NASA LeRC includes ring-cusp magnetic field plasma containment and dished two-grid ion optics. Based on past experience and demonstrated simplifications, power processors for these thrusters should have approximately 500 parts, a mass of 40 kg, and an efficiency near 0.94. Thrust vector control, via individual thruster gimbals, is a mature technology. High pressure, gaseous xenon propellant storage and control schemes, using flight qualified hardware, result in propellant tankage fractions between 0.1 and 0.2. In-space and ground integration testing has demonstrated that ion propulsion systems can be successfully integrated with their host spacecraft. Ion propulsion system technologies are mature and can significantly enhance and/or enable a variety of missions in the nation's space propulsion program.

Rawlin, V. K.; Patterson, M. J.; Gruber, R. P.

1990-01-01

154

The XENON1T Dark Matter Search Experiment  

NASA Astrophysics Data System (ADS)

The worldwide race towards direct dark matter detection in the form of WIMPs has been dramatically accelerated by the remarkable progress and evolution of liquid xenon time projection chambers (LXeTPCs). With a realistic discovery potential, XENON100 has already reached a sensitivity of 7E-45 cm^2, and continues to accrue data at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy towards its ultimate sensitivity reach at the 2E-45 cm^2 level for the spin-independent WIMP-nucleon cross-section. To fully explore the favored parameter space for WIMP dark matter in search of a first robust and statistically significant discovery, or to confirm any hint of a signal from XENON100, the next phase of the XENON program will be a detector at the ton scale - XENON1T. The XENON1T detector, based on 2.2 ton of LXe viewed by low radioactivity photomultiplier tubes and housed in a water Cherenkov muon veto at LNGS, is presented. The detector design is advancing and construction of major systems will begin in 2012, with data taking beginning in 2015. Capable of probing WIMP interaction cross-sections to ˜2E-47cm^2 within 2 years of operation, XENON1T will provide the sensitivity to probe a particularly favorable region of electroweak physics.

Ghag, Chamkaur

2012-03-01

155

Status of the XENON Direct Dark Matter Detection Experiment  

NASA Astrophysics Data System (ADS)

The XENON collaboration is developing a dark matter detector using liquid xenon (LXe) as the target medium for detecting Weakly Interacting Massive Particles (WIMPs). The goal of the collaboration is to operate an array of LXe time projection chambers (TPCs) with 1000 times greater sensitivity to WIMPs than current direct dark matter detection experiments. Recent measurements by members of the XENON collaboration demonstrate the promise of the LXe TPC approach, particularly measurements of the scintillation efficiency and charge extraction from nuclear recoils in LXe. The collaboration is currently installing a 10 kg fiducial volume prototype in the Gran Sasso National Laboratory in Italy for low background operation.

Hasty, Richard

2006-04-01

156

A Xenon Condenser with a Remote Liquid Storage Vessel  

E-print Network

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.

S. Slutsky; Y. -R. Yen; H. Breuer; A. Dobi; C. Hall; T. Langford; D. S. Leonard; L. J. Kaufman; V. Strickland; N. Voskanian

2009-07-25

157

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

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

J. Renner; V. M. Gehman; A. Goldschmidt; H. S. Matis; T. Miller; Y. Nakajima; D. Nygren; C. A. B. Oliveira; D. Shuman; V. Álvarez; F. I. G. Borges; S. Cárcel; J. Castel; S. Cebrián; A. Cervera; C. A. N. Conde; T. Dafni; T. H. V. T. Dias; J. Díaz; R. Esteve; P. Evtoukhovitch; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; A. Gil; H. Gómez; J. J. Gómez-Cadenas; D. González-Díaz; R. M. Gutiérrez; J. Hauptman; J. A. Hernando Morata; D. C. Herrera; F. J. Iguaz; I. G. Irastorza; M. A. Jinete; L. Labarga; A. Laing; I. Liubarsky; J. A. M. Lopes; D. Lorca; M. Losada; G. Luzón; A. Marí; J. Martín-Albo; A. Martínez; A. Moiseenko; F. Monrabal; M. Monserrate; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muñoz Vidal; H. Natal da Luz; G. Navarro; M. Nebot-Guinot; R. Palma; J. Pérez; J. L. Pérez Aparicio; L. Ripoll; A. Rodríguez; J. Rodríguez; F. P. Santos; J. M. F. dos Santos; L. Seguí; L. Serra; A. Simón; C. Sofka; M. Sorel; J. F. Toledo; A. Tomás; J. Torrent; Z. Tsamalaidze; J. F. C. A. Veloso; J. A. Villar; R. C. Webb; J. White; N. Yahlali

2014-09-09

158

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

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

Renner, J; Goldschmidt, A; Matis, H S; Miller, T; Nakajima, Y; Nygren, D; Oliveira, C A B; Shuman, D; Álvarez, V; Borges, F I G; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, J; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gil, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Moiseenko, A; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Palma, R; Pérez, J; Aparicio, J L Pérez; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Seguí, L; Serra, L; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R C; White, J; Yahlali, N

2014-01-01

159

CARBON DIOXIDE EMISSION REDUCTION  

E-print Network

CARBON DIOXIDE EMISSION REDUCTION TECHNOLOGIES AND MEASURES IN US INDUSTRIAL SECTOR FINAL REPORT TO KOREA ENVIRONMENT INSTITUTE FEBRUARY 2007 #12;B #12;C CARBON DIOXIDE EMISSION REDUCTION TECHNOLOGIES.5 Primary Energy Use and Carbon Dioxide Emissions for Selected US Chemical Subsectors in 1994

Delaware, University of

160

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

161

Ba+ Ion Mobility in Liquid Xenon  

NASA Astrophysics Data System (ADS)

The mobility of Ba+ ions in liquid xenon has been measured for the first time in a temperature range from 163 to 182 K. Preliminary results show that the mobility is 0.000158(30) cm^2/(V s) at 170 K. A slight decrease in the mobility with increasing temperature is observed. Due to the force of 10^7-10^8 ions on the liquid, it was necessary to make a correction to the apparent mobility which is dependent on the total amount of Ba+ charge. These measurements are motivated by our development of a new method to search for the neutrino mass, which will use laser tagging of single 136Ba+ daughter ions in liquid 136Xe.

Taylor, Wade; Jeng Fairbank, Shie-Chang, Jr.; Miyajima, Mitsuhiro

2002-10-01

162

Modeling Pulse Characteristics in Xenon with NEST  

E-print Network

A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, effects such as the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, parameters such as ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

Mock, Jeremy; Kazkaz, Kareem; Szydagis, Matthew; Tripathi, Mani; Uvarov, Sergey; Woods, Michael; Walsh, Nicholas

2013-01-01

163

Xenon plasma with caesium as additive  

NASA Astrophysics Data System (ADS)

The concentration dependence of xenon plasma with caesium as additive in the temperature region of 2 000 K to 20 000 K has been analysed. Plasma has been considered as weakly nonideal in the complete local thermodynamic equilibrium and the interaction between plasma and vessel walls was not taken into account. The values of some of the parameters for nonideality of plasma with 1% of caesium ( ?=0·01010) and 10% of caesium ( ?=0·11111) are computed, for initial pressure in plasma of p 0=13 000 Pa and initial temperature T 0=1 000 K. Also the ratio of electrical conductivity of plasma computed by Lorentz's formula and electrical conductivity computed by Spitzer's formula in the same temperature interval has been analysed.

Stojilkovic, S. M.; Novakovi?, N. V.; Živkovi?, Lj. M.

1986-12-01

164

Fission xenon from extinct Pu-244 in 14,301.  

NASA Technical Reports Server (NTRS)

Xenon extracted in step-wise heating of lunar breccia 14,301 contains a fission-like component in excess of that attributable to uranium decay during the age of the solar system. There seems to be no adequate source for this component other than Pu-244. Verification that this component is in fact due to the spontaneous fission of extinct Pu-244 comes from the derived spectrum which is similar to that observed from artificially produced Pu-244. It thus appears that Pu-244 was extant at the time lunar crustal material cooled sufficiently to arrest the thermal diffusion of xenon. Subsequent history has apparently maintained the isotopic integrity of plutonium fission xenon. Of major importance are details of the storage itself. Either the fission component is the result of in situ fission of Pu-244 and subsequent storage in 14,301 material, or the fission xenon was stored in an intermediate reservoir before incorporation into 14,301.

Drozd, R.; Hohenberg, C. M.; Ragan, D.

1972-01-01

165

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

166

The unbearable lightness of being: CDMS versus XENON  

SciTech Connect

The CDMS-II collaboration has reported 3 events in a Si detector, which are consistent with being nuclear recoils due to scattering of Galactic dark matter particles with a mass of ? 8.6 GeV and a cross-section on neutrons of ? 2 × 10{sup ?41} cm{sup 2}. While a previous result from the XENON10 experiment has supposedly ruled out such particles as dark matter, we find by reanalysing the XENON10 data that this is not the case. Some tension remains however with the upper limit placed by the XENON100 experiment, independently of astrophysical uncertainties concerning the Galactic dark matter distribution. We explore possible ways of ameliorating this tension by altering the properties of dark matter interactions. Nevertheless, even with standard couplings, light dark matter is consistent with both CDMS and XENON10/100.

Frandsen, Mads T. [CP3-Origins and the Danish Institute for Advanced Study, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Kahlhoefer, Felix; Sarkar, Subir [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); McCabe, Christopher [Institute for Particle Physics Phenomenology, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Schmidt-Hoberg, Kai, E-mail: frandsen@cp3-origins.net, E-mail: felix.kahlhoefer@physics.ox.ac.uk, E-mail: christopher.mccabe@durham.ac.uk, E-mail: s.sarkar@physics.ox.ac.uk, E-mail: kai.schmidt-hoberg@cern.ch [Theory Division, CERN, 1211 Geneva 23 (Switzerland)

2013-07-01

167

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

168

A gamma-ray imaging telescope based on liquid xenon  

NASA Technical Reports Server (NTRS)

A liquid-xenon time projection chamber (TPC) is discussed in terms of its utility as an imaging telescope for high energy astrophysics. The concept exploits the efficiency of xenon as an ionization and scintillation medium for imaging astrophysical gamma-ray sources. The design fundamentally follows the approach of an ionization calorimeter functioning as a TPC dedicated to 3D tracking. A schematic diagram of the instrument is presented, and the device measures the ionization signals - resulting from gamma-ray interactions with xenon - on collection electrodes. The liquid xenon instrument permits the identification of the direction of the Compton electron and thereby determines the location of the source. The energy region of 1-30 MeV is covered by the instrument, and source localization is possible for the entire range.

Aprile, Elena; Mukherjee, Reshmi; Suzuki, Masayo

1990-01-01

169

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

170

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

171

Introducing Hyperpolarized Xenon131 Directly Detected by NMR Spectroscopy  

Microsoft Academic Search

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

Karl Stupic; Zackary Cleveland; Galina Pavlovskaya; Thomas Meersmann

2007-01-01

172

Detection of liquid xenon scintillation light with a silicon photomultiplier  

Microsoft Academic Search

We have studied the feasibility of a silicon photomultiplier (SiPM) to detect liquid xenon (LXe) scintillation light. The SiPM was operated inside a small volume of pure liquid xenon (LXe), at -95?C, irradiated with an internal 241Am ? source. The gain of the SiPM at this temperature was estimated to be 1.8×106 at a 52V bias voltage. Based on the

E. Aprile; P. Cushman; K. Ni; P. Shagin

2006-01-01

173

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

174

Scintillation luminescence for high-pressure xenon gas  

NASA Astrophysics Data System (ADS)

Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of xenon atoms (N), E/N from 0 to 5×10-18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10-18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gas[H2-0.2%], at 2.6MPa was also measured. Scintillation yield of the Xe-H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.

Kobayashi, S.; Hasebe, N.; Igarashi, T.; Kobayashi, M.-N.; Miyachi, T.; Miyajima, M.; Okada, H.; Okudaira, O.; Tezuka, C.; Yokoyama, E.; Doke, T.; Shibamura, E.; Dmitrenko, V. V.; Ulin, S. E.; Vlasik, K. F.

2004-09-01

175

A coherent understanding of low-energy nuclear recoils in liquid xenon  

E-print Network

Liquid xenon detectors such as XENON10 and XENON100 obtain a significant fraction of their sensitivity to light (xenon for nuclear recoils also bears heavily on detector sensitivity, yet numerous measurements have not succeeded in obtaining concordant results. In this article we show that the ratio of detected ionization to scintillation can be leveraged to constrain the scintillation yield. We also present a rigorous treatment of liquid xenon detector threshold and energy resolution. Notably, the effective energy resolution differs significantly from a simple Poisson distribution. We conclude with a calculation of dark matter exclusion limits, and show that existing data from liquid xenon detectors strongly constrain recent interpretations of light dark matter.

Peter Sorensen

2010-09-07

176

Solubility of xenon in amino-acid solutions. II. Nine less-soluble amino acids  

NASA Astrophysics Data System (ADS)

Ostwald solubility (L) of xenon gas, as the radioisotope 133Xe, has been measured as a function of solute concentration, at 25.0 °C, in aqueous solutions of nine amino acids. The amino-acid concentrations investigated covered much of their solubility ranges in water, viz., asparagine monohydrate (0-0.19 M), cysteine (0-1.16 M), glutamine (0-0.22 M), histidine (0-0.26 M), isoleucine (0-0.19 M), methionine (0-0.22 M), serine (0-0.38 M), threonine (0-1.4 M), and valine (0-0.34 M). We have previously reported solubility results for aqueous solutions of six other, generally more soluble, amino acids (alanine, arginine, glycine, hydroxyproline, lysine, and proline), of sucrose and sodium chloride. In general, L decreases approximately linearly with increasing solute concentration in these solutions. If we postulate that the observed decreases in gas solubility are due to hydration, the results under some assumptions can be used to calculate hydration numbers (H), i.e., the number of H2O molecules associated with each amino-acid solute molecule. The average values of hydration number (H¯) obtained at 25.0 °C are 15.3±1.5 for asparagine, 6.8±0.3 for cysteine, 11.5±1.1 for glutamine, 7.3±0.7 for histidine, 5.9±0.4 for isoleucine, 10.6±0.8 for methionine, 11.2±1.3 for serine, 7.7± 1.0 for threonine, and 6.6±0.6 for valine. We have also measured the temperature dependence of solubility L(T) from 5-40 °C for arginine, glycine, and proline, and obtained hydration numbers H¯(T) in this range. Between 25-40 °C, arginine has an H¯ near zero. This may be evidence for an attractive interaction between xenon and arginine molecules in aqueous solution.

Kennan, Richard P.; Himm, Jeffrey F.; Pollack, Gerald L.

1988-05-01

177

The carbon dioxide cycle  

USGS Publications Warehouse

The seasonal CO2 cycle on Mars refers to the exchange of carbon dioxide between dry ice in the seasonal polar caps and gaseous carbon dioxide in the atmosphere. This review focuses on breakthroughs in understanding the process involving seasonal carbon dioxide phase changes that have occurred as a result of observations by Mars Global Surveyor. ?? 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

James, P.B.; Hansen, G.B.; Titus, T.N.

2005-01-01

178

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.

179

Prospects for Barium Tagging in Gaseous Xenon  

SciTech Connect

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. It is clear from this study that electrospray is a convenient mechanism for producing Ba++ is gas at atmospheric pressure. It is likely that the source will perform just as effectively at higher pressures. Even though the source region has water vapour and methanol vapour at the 0.3% level, there is no evidence for molecular formation. The use of TEA offers an effective method to achieve the charge state conversion. The overall design of the ion extraction from high pressure to vacuum is very similar to the scheme proposed for the final detector and this appears to work well although the efficiency is not yet determined.

Sinclair, D.; /Carleton U. /TRIUMF; Rollin, E.; /Carleton U.; Smith, J.; /Carleton U.; Mommers, A.; /Ottawa U.; Ackerman, N.; /SLAC; Aharmim, B.; /Laurentian U.; Auger, M.; /Bern U., LHEP; Barbeau, P.S.; /Stanford U., Phys. Dept.; Benitez-Medina, C.; /Colorado State U.; Breidenbach, M.; /SLAC; Burenkov, A.; /Moscow, ITEP; Cook, S.; /SLAC; Coppens, A.; /Carleton U.; Daniels, T.; /Massachusetts U., Amherst; DeVoe, R.; /Stanford U., Phys. Dept.; Dobi, A.; /Maryland U.; Dolinski, M.J.; Donato, K.; /Stanford U., Phys. Dept.; Fairbank, W., Jr.; /Colorado State U.; Farine, J.; /Laurentian U.; Giroux, G.; /Bern U., LHEP /Carleton U. /Stanford U., Phys. Dept. /Carleton U. /Laurentian U. /Carleton U. /SLAC /Indiana U. /Indiana U., CEEM /Korea U. /Stanford U., Phys. Dept. /SLAC /Alabama U. /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Stanford U., Phys. Dept. /Alabama U. /Massachusetts U., Amherst /SLAC /Alabama U. /SLAC /Maryland U. /Moscow, ITEP /Stanford U., Phys. Dept. /Maryland U. /Bern U., LHEP /Laurentian U. /SLAC /Maryland U.

2012-05-03

180

Measurement of the refractive index of liquid xenon for intrinsic scintillation light  

Microsoft Academic Search

Measurement of the refractive index of liquid xenon (LXe) for intrinsic scintillation light was carried out. The value obtained at ? = 180 nm is equal to 1.5655 ± 0.0024 ± 0.0078 for the xenon triple point.

L. M Barkov; A. A Grebenuk; N. M Ryskulov; P. Yu Stepanov; S. G Zverev

1996-01-01

181

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

182

Xenon low-n Rydberg states in supercritical argon near the critical point  

E-print Network

Xenon low-n Rydberg states in supercritical argon near the critical point Luxi Li a,b , Xianbo Shi simulation of the 6s and 6s Rydberg states (including the blue satellite bands) of xenon doped into argon

Findley, Gary L.

183

Calibration of the XENON100 Time Projection Chamber  

NASA Astrophysics Data System (ADS)

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. Following the successful performance of the XENON10, we have designed and built a new detector with a total Xe mass of 170 kg, and with 100 times less background. The XENON100 detector is currently undergoing commissioning at the Gran Sasso Underground Laboratory. The calibration of the detector with gamma sources and with low energy neutrons is essential to determine the response to electron and nuclear recoils, and their discrimination based on the ratio of ionization to scintillation, as well as on event positioning and scattering-multiplicity within the active liquid volume. External gamma sources used for the XENON100 calibration include Cs-137, Co-57 and Co-60. An external Am-Be source is used for irradiation by neutrons. Additionally, we have been testing mixing Kr-83m (tau=12.6 hr, 18 and 32 keV electrons and 13 keV x-rays) into the LXe target, as internal source of low energy electron recoils. We discuss how different detector performance parameters such as light yield and electron lifetime can be inferred from these calibrations and show how the spatial dependence of some other parameters (light collection efficiency for example) can be obtained. We also present comparisons of results from calibrations with Monte Carlo simulations.

Lim, Kyungeun

2009-05-01

184

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

185

Spectrally Resolved Magnetic Resonance Imaging of the XenonBiosensor  

SciTech Connect

Due to its ability to non-invasively record images, as well as elucidate molecular structure, nuclear magnetic resonance is the method of choice for applications as widespread as chemical analysis and medical diagnostics. Its detection threshold is, however, limited by the small polarization of nuclear spins in even the highest available magnetic fields. This limitation can, under certain circumstances, be alleviated by using hyper-polarized substances. Xenon biosensors make use of the sensitivity gain of hyperpolarized xenon to provide magnetic resonance detection capability for a specific low-concentration target. They consist of a cryptophane cage, which binds one xenon atom, and which has been connected via a linker to a targeting moiety such as a ligand or antibody. Recent work has shown the possibility of using the xenon biosensor to detect small amounts of a substance in a heterogeneous environment by NMR. Here, we demonstrate that magnetic resonance (MR) provides the capability to obtain spectrally and spatially resolved images of the distribution of immobilized biosensor, opening the possibility for using the xenon biosensor for targeted imaging.

Hilty, Christian; Lowery, Thomas; Wemmer, David; Pines, Alexander

2005-07-15

186

Influence of radiation damage on xenon diffusion in silicon carbide  

NASA Astrophysics Data System (ADS)

Diffusion of xenon in poly and single crystalline silicon carbide and the possible influence of radiation damage on it are investigated. For this purpose 360 keV xenon ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and xenon retention during isochronal and isothermal annealing up to temperatures of 1500 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by ?-particle channelling. No diffusion or xenon loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature serious erosion of the implanted surface occurred, which made any analysis impossible. No diffusion or xenon loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC.

Friedland, E.; Gärtner, K.; Hlatshwayo, T. T.; van der Berg, N. G.; Thabethe, T. T.

2014-08-01

187

Xenon-related analgesia: a new target for pain treatment.  

PubMed

The noble gas xenon has been known for >50 years in the field of anesthesia with an emerging series of favorable features; several clinical and preclinical studies performed over the last years reveal a renewed interest because they substantially agree on attributing relevant analgesic properties to xenon. The main mechanism of action is the inhibition of N-methyl-D-aspartate receptors of glutamate; it involves the blocking of painful stimuli transmissions from peripheral tissues to the brain and it also avoids the development of pain hypersensitivity. Therefore, this mechanism is responsible for the inhibition of pain transmission at spinal and supraspinal levels, as well as the cortical level. In all these levels of pain pathways, as the development of hyperalgesia is possible, xenon efficacy can also be based on the blocking of these processes. Several forms of pain share such mechanisms in their maintenance, and xenon can be successfully used at low dosages, which have no effects on vital parameters. The literature shows that analgesic features could also emerge outside the field of anesthesia; thus, this could permit xenon to have a larger usage according to local availability. PMID:23328329

Giacalone, Marilù; Abramo, Antonio; Giunta, Francesco; Forfori, Francesco

2013-07-01

188

Separation of rare gases and chiral molecules by selective binding in porous organic cages.  

PubMed

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation. PMID:25038731

Chen, Linjiang; Reiss, Paul S; Chong, Samantha Y; Holden, Daniel; Jelfs, Kim E; Hasell, Tom; Little, Marc A; Kewley, Adam; Briggs, Michael E; Stephenson, Andrew; Thomas, K Mark; Armstrong, Jayne A; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M; Thallapally, Praveen K; Cooper, Andrew I

2014-10-01

189

Separation of rare gases and chiral molecules by selective binding in porous organic cages  

NASA Astrophysics Data System (ADS)

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation.

Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. Mark; Armstrong, Jayne A.; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

2014-10-01

190

democrite-00024907,version2-23Nov2005 Experimental study of a liquid Xenon PET  

E-print Network

democrite-00024907,version2-23Nov2005 Experimental study of a liquid Xenon PET prototype module M A detector using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the liquid Xenon properties. It does

Paris-Sud XI, Université de

191

RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES  

E-print Network

L- 105 RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES M. CHENEVIER, N*(3P2) by two-body collisions with argon k3, and by three-body collisions with an argon and a xenon Abstracts 34.50H - 82.20 Introduction. - Recently several types of xenon halide excimer laser have been

Paris-Sud XI, Université de

192

Experimental data analysis on xenon above the critical temperature from nonlinear renormalization group  

E-print Network

L-127 Experimental data analysis on xenon above the critical temperature from nonlinear and specific heat data on xenon using the recent non- linear renormalization group calculations obtained shown to be necessary in the analysis of experimental data on xenon [1] at equilibrium along its

Paris-Sud XI, Université de

193

Scattering of xenon from Ni,,111...: Collision-induced corrugation and energy transfer dynamics  

E-print Network

Scattering of xenon from Ni,,111...: Collision-induced corrugation and energy transfer dynamics in which a beam of xenon atoms collides with a clean Ni 111 surface, and the speed and angular is independent of initial and final scattering angles. This result is attributed to multiple xenon

Zare, Richard N.

194

Simulation and evaluation of a new PET system based on liquid xenon as detection medium  

E-print Network

Simulation and evaluation of a new PET system based on liquid xenon as detection medium J ionization potential, liquid xenon is an excellent medium for the tracking and the accurate energy measurement of -rays in the MeV energy domain. The use of liquid xenon associated to a micro gap structure

Paris-Sud XI, Université de

195

Turbidity measurements in xenon reanalyzed using the master crossover functions Y. Garrabos and C. Lecoutre  

E-print Network

Turbidity measurements in xenon reanalyzed using the master crossover functions Y. Garrabos and C.5 K along the critical isochore of homogeneous xenon are reanalyzed using the master crossover. This excellent agreement conrms that the Ising-like critical behavior of xenon can be described in conformity

Boyer, Edmond

196

Sublimative desorption of xenon from Ru(100) Gabriel Kerner, Ori Stein, Yigal Lilach, and Micha Asscher*  

E-print Network

Sublimative desorption of xenon from Ru(100) Gabriel Kerner, Ori Stein, Yigal Lilach, and Micha , George and co-workers have investigated the submonolayer xenon diffusion on a stepped Pt 11,11,9 surface addressed the 2D melting and diffusion of multilayer xenon on surfaces. In addition to its basic importance

Asscher, Micha

197

Magnetic resonance imaging of laser polarized liquid xenon C. H. Tseng,1,2  

E-print Network

Magnetic resonance imaging of laser polarized liquid xenon C. H. Tseng,1,2 R. W. Mair,1 G. P. Wong liquid xenon, and image exchange between the liquid and vapor phases. The exceptionally large averaging. Applications may include imaging of density equilibration and convective flow near xenon's liquid

Walsworth, Ronald L.

198

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma I.E. Garkusha1  

E-print Network

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma Compressor I.E. Garkusha1 , V generation lithography. In both approaches xenon has advantage to be used as working gas due to considerably. This paper presents the investigations xenon plasma streams generated by magnetoplasma compressor (MPC

Harilal, S. S.

199

Xenon diffusion studies with prompt gamma activation analysis Carlos A. Rios Perez Justin D. Lowrey  

E-print Network

Xenon diffusion studies with prompt gamma activation analysis Carlos A. Rios Perez · Justin D 2011 Abstract Developing a better understanding of xenon transport through porous systems is critical rates of xenon and argon gases through a porous medium. The University of Texas at Austin maintains

Deinert, Mark

200

Diamagnetic behaviour of xenon Rydberg states studied by the R.F. optogalvanic method  

E-print Network

249 Diamagnetic behaviour of xenon Rydberg states studied by the R.F. optogalvanic method J. P behaviour of xenon nf Rydberg states is studied using single-mode dye laser excita- tion and an R xenon can offer interesting opportunities for studies of this type. We want furthermore to emphasize

Paris-Sud XI, Université de

201

Exploring Surfaces and Cavities in Lipoxygenase and Other Proteins by Hyperpolarized Xenon-129 NMR  

E-print Network

Exploring Surfaces and Cavities in Lipoxygenase and Other Proteins by Hyperpolarized Xenon-129 NMR: This paper presents an exploratory study of the binding interactions of xenon with the surface of several studies of Xe bound to the surface of materials,3,4 medical imaging of xenon in lungs5 and blood,6

Ronquist, Fredrik

202

Methoden zur optischen Qualitatskontrolle Anwendung in der Produktion von Xenon-Lampen  

E-print Network

Methoden zur optischen Qualit¨atskontrolle Anwendung in der Produktion von Xenon Arbeit werden Methoden zur optischen Qualit¨atskontrolle von Xenon- Lampen evaluiert. Die automatische-Nearest-Neighbor eingeteilt werden. Die besten Ergebnisse bei der Klassifikation von geschwei�ten und ungeschwei�ten Xenon

203

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

204

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole Lecoutre  

E-print Network

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole the singular behaviors of the isothermal compressibility of xenon along the critical isochore in the homogeneous domain and the vapor-liquid coexisting densities of xenon in the nonhomogenous domain

Boyer, Edmond

205

Mechanistic Insights into Xenon Inhibition of NMDA Receptors from MD Simulations Lu Tian Liu,  

E-print Network

Mechanistic Insights into Xenon Inhibition of NMDA Receptors from MD Simulations Lu Tian Liu, Yan) receptors has been viewed as a primary cause of xenon anesthesia, yet the mechanism is unclear. Here, we investigated interactions between xenon and the ligand-binding domain (LBD) of a NMDA receptor and examined

Xu, Yan

206

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter detectors  

E-print Network

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter contamination in xenon dark matter detectors E. Aprile, T. Yoon,a) A. Loose, L. W. Goetzke, and T. Zelevinsky for the sensitivity achievable with liquid xenon dark matter detectors beyond the current generation. Since Ar and Kr

Zelevinsky, Tanya

207

Angle-resolved photoemission of xenon adsorbed on Pt(111) : commensurate and incommensurate monolayers  

E-print Network

1753 Angle-resolved photoemission of xenon adsorbed on Pt(111) : commensurate and incommensurate The dispersion curves of the commensurate (~3 x ~3) R30° and the hexagonal compact incommensurate rotated xenon and particularly xenon layers form a hexagonal (or nearly hexagonal) compact structure on most single crystals [1

Paris-Sud XI, Université de

208

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

209

DISCOVERY OF THE TWO-NEUTRINO DOUBLE-BETA DECAY OF XENON-136 WITH EXO-200  

E-print Network

DISCOVERY OF THE TWO-NEUTRINO DOUBLE-BETA DECAY OF XENON-136 WITH EXO-200 A DISSERTATION SUBMITTED Enriched Xenon Observatory (EXO-200) detector is currently taking data to search for the neutrinoless enriched liquid xenon. The analysis presented here describes the recent observation with EXO-200 of the two

Gratta, Giorgio

210

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

To understand the superiority of liquid xenon as detector medium, at first, the scintillation mechanism of liquid rare gases is explained and the absolute scintillation yield in liquid xenon is estimated and then the decay shapes of scintillation lights from liquid xenon, which are faster than those of scintillation lights from crystal scintillators recently developed, are summarized. In addition, only

T. Doke

2005-01-01

211

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

We review the scintillation mechanism of liquid rare gases and estimate the absolute scintillation yield of liquid xenon in order to understand the superiority of liquid xenon as a detector medium. The decays of scintillation light from liquid xenon, which are faster than those of scintillation light from crystal scintillators, are summarized. New photomultipliers with high quantum efficiency that can

Tadayoshi Doke

2006-01-01

212

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.

2014-01-28

213

Carbon Dioxide Emission Estimates  

NSDL National Science Digital Library

The Carbon Dioxide Information Analysis Center of the Oak Ridge National Laboratory provides this new data on carbon dioxide emissions from fossil fuel burning, hydraulic cement production, and gas flaring in 1995. Data for one degree grid cells can be downloaded from the site in addition to code for analysis of the data.

214

Carbon Dioxide & Global Warming  

E-print Network

Carbon Dioxide & Global Warming University of MiaMi rosenstiel sChool of Marine anD atMospheriC s ­ it allows sunlight in, but gases in the atmosphere, especially carbon dioxide (CO2 ), allow less to breathe. Respi- ration by these organisms returns this carbon to the atmosphere as CO2 . Unfortunately

Miami, University of

215

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

216

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

217

Reflectance of Polytetrafluoroethylene (PTFE) for Xenon Scintillation Light  

E-print Network

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 wavelength region (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. Fluoropolymers, namely ETFE, FEP and PFA were also measured.

Silva, C; Pereira, A; Chepel, V; Lopes, M I; Solovov, V

2009-01-01

218

Background simulations of the XENON100 dark matter detector  

NASA Astrophysics Data System (ADS)

The XENON100 detector is a dual-phase xenon time projection chamber (XeTPC) used to search for dark matter in the form of weakly interacting massive particles (WIMPs) by measuring simultaneously the scintillation and ionization signals produced by nuclear recoils. The 65 kg XeTPC is instrumented by 178 PMTs and is surrounded by a 85 kg LXe active veto with 64 PMTs. All materials and components used to build the detector (PMTs, PMT bases, stainless steel, PTFE, copper, etc) have been screened with high purity germanium detectors operating at the Gran Sasso underground laboratory. Special attention has been paid to the choice of construction materials. Using the measured radioactivity as input to the Monte Carlo, we have simulated the response of the XENON100 detector to obtain the expected gamma and neutron backgrounds, which largely determine the sensivity reach of the experiment.

Plante, Guillaume

2008-04-01

219

Detection of liquid xenon scintillation light with a silicon photomultiplier  

NASA Astrophysics Data System (ADS)

We have studied the feasibility of a silicon photomultiplier (SiPM) to detect liquid xenon (LXe) scintillation light. The SiPM was operated inside a small volume of pure liquid xenon (LXe), at -95C, irradiated with an internal 241Am ? source. The gain of the SiPM at this temperature was estimated to be 1.8×10 at a 52 V bias voltage. Based on the geometry of the setup, the quantum efficiency of the SiPM was estimated to be 22% (5.5% is the photon detection efficiency) at the Xe wavelength of 178 nm. The low excess noise factor (about 1.05), high single photoelectron detection efficiency, and low bias voltage of SiPMs make them attractive alternative UV photon detection devices to photomultiplier tubes (PMTs) for liquid xenon detectors, especially for experiments requiring a very low energy detection threshold, such as neutralino dark matter searches.

Aprile, E.; Cushman, P.; Ni, K.; Shagin, P.

2006-01-01

220

Size and wavelength dependent photoionisation of xenon clusters  

NASA Astrophysics Data System (ADS)

Size and wavelength dependent photoionisation studies have been carried out on xenon clusters (Xen) using nanosecond long gigawatt intensity laser pulses. The ionic species (Xe+, Xe2+, … Xe10+) were characterized by time-of flight mass spectrometry. It is observed that higher the irradiation wavelength, higher is the maximum observed charge state of xenon ion. Clusters of on irradiation with 532 nm pulses yielded only singly charged ions (Xe+, … Xe4+) whereas produced multiply charged Xe ions (Xen+, n = 1-10). With increase in cluster size, kinetic energy of multiply charged xenon ions was found to increase, while the threshold laser intensity for inducing multiple ionisation within the cluster decreases from 9 × 109 W/cm2 for to 3 × 109 W/cm2 for .

Das, Soumitra; Badani, Purav M.; Sharma, Pramod; Vatsa, Rajesh K.

2012-11-01

221

High-pressure xenon detector development at Constellation Technology Corporation  

NASA Astrophysics Data System (ADS)

Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities (~0.3 g/cm 3-0.5 g/cm 3) and good energy resolution (2%-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and Germanium detectors. Until recently, difficulties with obtaining sufficient Xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990's, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Here we will discuss our development of a mobile, large area, spectroscopic array.

Austin, Robert A.; Bastian, Lloyd F.

2006-08-01

222

Measuring Double-Electron Capture with Liquid Xenon Experiments  

E-print Network

We investigate the possibilities of observing the decay mode for $^{124}$Xe in which two electrons are captured, two neutrinos are emitted, and the final daughter nucleus is in its ground state, using dark matter experiments with liquid xenon. The first upper limit of the decay half-life is calculated to be 2.16$\\times10^{21}$ years at a 90% confidence level obtained with the published background data from the XENON100 experiment. Employing a known background model from the Large Underground Xenon (LUX) experiment, we predict that the detection of double-electron capture of $^{124}$Xe to the ground state of $^{124}$Te with LUX will have approximately 115 events, assuming a half-life of 2.9 $\\times$ 10$^{21}$ years. We conclude that measuring $^{124}$Xe 2$\

Mei, D -M; Wei, W -Z; Zhang, C

2013-01-01

223

Time profile of the scintillation from liquid and gaseous xenon  

NASA Astrophysics Data System (ADS)

The decay time profile of vacuum ultraviolet scintillation induced by electronic recoils has been studied for liquid and gaseous xenon. The scintillation light from xenon excited by a gamma source was measured by using two vacuum ultraviolet sensitive photomultipliers, one for detecting scintillation and the other for counting photons of weak monochromatic light. The analysis results based on the time-correlated single photon counting method show that the time profile in the 176 nm scintillation decay curve for liquid xenon is consistent with a single exponential component and the decay time constant is 31.5±1.3 ns. This constant does not change significantly for pressure ranges between 90 kPa and 130 kPa. There is no emission wavelength dependence of the decay constant. The result corresponds to an average on electronic recoil energies up to 1.3 MeV.

Murayama, Ikuko; Nakamura, Shogo

2014-11-01

224

SUSY Dark Matter In Light Of CDMS/XENON Limits  

E-print Network

In this talk we briefly review the current CDMS/XENON constraints on the neutralino dark matter in three popular supersymmetric models: the minimal (MSSM), the next-to-minimal (NMSSM) and the nearly minimal (nMSSM). The constraints from the dark matter relic density and various collider experiments are also taken into account. The conclusion is that for each model the current CDMS/XENON limits can readily exclude a large part of the parameter space allowed by other constraints and the future SuperCDMS or XENON100 can cover most of the allowed parameter space. The implication for the Higgs search at the LHC is also discussed. It is found that in the currently allowed parameter space the MSSM charged Higgs boson is quite unlikely to be discovered at the LHC while the neutral Higgs bosons $H$ and $A$ may be accessible at the LHC in the parameter space with a large $\\mu$ parameter.

Jin Min Yang

2011-02-24

225

Direct Dark Matter Searches with CDMS and XENON  

E-print Network

The Cryogenic Dark Matter Search (CDMS) and XENON experiments aim to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering on the target nuclei. The experiments use different techniques to suppress background event rates to the minimum, and at the same time, to achieve a high WIMP detection rate. The operation of cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine yielded the most stringent spin-independent WIMP-nucleon cross-section (~10^{-43} cm^2) at a WIMP mass of 60 GeV/c^2. The two-phase xenon detector of the XENON10 experiment is currently taking data in the Gran Sasso underground lab and promising preliminary results were recently reported. Both experiments are expected to increase their WIMP sensitivity by a one order of magnitude in the scheduled science runs for 2007.

Kaixuan Ni; Laura Baudis

2006-11-09

226

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

227

Measuring double-electron capture with liquid xenon experiments  

NASA Astrophysics Data System (ADS)

We investigate the possibilities of observing the decay mode for 124Xe in which two electrons are captured, two neutrinos are emitted, and the final daughter nucleus is in its ground state, using dark matter experiments with liquid xenon. The first upper limit of the decay half-life is calculated to be 1.66 × 1021 years at a 90% confidence level (C.L.) obtained with the published background data from the XENON100 experiment. Employing a known background model from the large underground xenon (LUX) experiment, we predict that the detection of double-electron capture of 124Xe to the ground state of 124Te with LUX will have approximately 115 events, assuming a half-life of 2.9 × 1021 years. We conclude that measuring 124Xe 2? double-electron capture to the ground state of 124Te can be performed more precisely with the proposed LUX-Zeplin (LZ) experiment.

Mei, D.-M.; Marshall, I.; Wei, W.-Z.; Zhang, C.

2014-01-01

228

A linear ion trap for the Enriched Xenon Observatory EXO  

NASA Astrophysics Data System (ADS)

The Enriched Xenon Observatory for double beta decay attempts to answer one of the greatest outstanding questions in neutrino physics by performing a direct measurement of the majorana neutrino mass through the investigation of neutrinoless double beta decay (0???) of ^136Xe. The major advantage of Xenon as a source is the ability to detect the Ba ion daughter directly through laser induced fluorescence spectroscopy; this technique would allow for an essentially background-free measurement. First investigations of Ba spectroscopy were done in a hyperbolic Paul-trap. This talk discusses the trapping of single barium ions in buffer gasses, as well as the design and implementation of a linear ion trap, which allows for external loading of ions, for use in the Barium tagging aspect of a liquid Xenon double beta decay experiment.

Flatt, Björn; Devoe, Ralph; Gratta, Giorgio; Green, Matthew; Wodin, Jesse

2006-04-01

229

Uranium dioxide films with xenon filled bubbles for fission gas behavior studies  

NASA Astrophysics Data System (ADS)

Electron beam evaporation and ion beam assisted deposition (IBAD) methods were utilized to fabricate depleted UO2 films and UO2 films with embedded Xe atoms, respectively. The films were fabricated at elevated temperature of 700 °C and also subsequently annealed at 1000 °C to induce grain growth and Xe atom redistribution. The goal of this work was to synthesize reference UO2 samples with controlled microstructures and Xe-filled bubble morphologies, without the effects attendant to rector irradiation-induced fission. Transmission electron microscopy (TEM) microstructural characterization revealed that fine Xe-filled bubbles nucleated in the as grown films and subsequent annealing resulted in noticeable bubble size increase. Reported results demonstrate the great potential IBAD techniques and UO2 films have for various areas of nuclear materials studies.

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

2014-09-01

230

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid, forces it to evaporate, and thus cools it down. We show that this temperature difference can be used for an efficient heat exchange process. We investigate the use of a commercial parallel plate heat exchanger with a small liquid xenon detector. Although we expected to be limited by the available cooling power to flow rates of about 2 SLPM, rates in excess of 12 SLPM can easily be sustained, limited only by the pump speed and the impedance of the flow loop. The heat exchanger operates with an efficiency of (96.8 +/- 0.5)%. This opens the possibility for fast xenon gas recirculation in large-scale experiments, while minimizing thermal losses.

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-03-04

231

Standardization of xenon-127 and measurement of photon emission intensities.  

PubMed

Xenon-127 was standardized by internal gas counting using three proportional counters in a differential arrangement to eliminate edge effects. The detection efficiency of the proportional counters was calculated by considering the cascade of events following the electron capture and associated gamma transitions. Activity per unit volume was measured with 0.7% relative standard uncertainty. Gamma-ray spectrometry was performed and absolute photon emission intensities were derived. This study shows that (127)Xe could be a surrogate for (133)Xe for the calibration of remote radio-xenon monitoring stations. PMID:24360861

Rodrigues, M; Lépy, M-C; Cassette, P; Mougeot, X; Bé, M M

2014-05-01

232

Coating Glass Cells with OTS The glass cells we use to polarize xenon or to store polarized  

E-print Network

Coating Glass Cells with OTS The glass cells we use to polarize xenon or to store polarized xenon need to be coated. This is because without coating wall collisions of the xenon can bring the xenon. The OTS (octadecyltrichlorosilane) we use consists of a long hydrocarbon chain

Walsworth, Ronald L.

233

Characterization of the Effects of Nonspecific Xenon–Protein Interactions on 129Xe Chemical Shifts in Aqueous Solution: Further Development of Xenon as a Biomolecular Probe  

Microsoft Academic Search

The sensitivity of 129Xe chemical shifts to weak nonspecific xenon–protein interactions has suggested the use of xenon to probe biomolecular structure and interactions. The realization of this potential necessitates a further understanding of how different macromolecular properties influence the 129Xe chemical shift in aqueous solution. Toward this goal, we have acquired 129Xe NMR spectra of xenon dissolved in amino acid,

Seth M. Rubin; Megan M. Spence; Alexander Pines; David E. Wemmer

2001-01-01

234

The XENON100 Dark Matter Experiment: Initial Performance and Projected Sensitivity  

NASA Astrophysics Data System (ADS)

The XENON Dark Matter Project aims at the direct detection of WIMPs (Weakly Interacting Massive Particles) with dual phase (liquid/gas) xenon time projection chambers (LXeTPCs). 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 150 kg of xenon. The detector, mounted in the same passive shield used for XENON10 at the Gran Sasso Underground Laboratory, is currently undergoing gamma calibration. Based on a similar design as XENON10, XENON100 features an increase in fiducial target mass of a factor of 10, with an overall background rate about 100 times lower. We report on the status of this development and discuss the projected sensitivity reach for dark matter detection.

Aprile, Elena

2008-04-01

235

In vivo NMR and MRI using injection delivery of laser-polarized?xenon  

PubMed Central

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo 129Xe NMR/MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold. PMID:9405680

Goodson, B. M.; Song, Y.-Q.; Taylor, R. E.; Schepkin, V. D.; Brennan, K. M.; Chingas, G. C.; Budinger, T. F.; Navon, G.; Pines, A.

1997-01-01

236

Discharge in an electromagnetic shock tube with preionization of xenon  

Microsoft Academic Search

Preionization of xenon, which creates a pressure gradient between the discharge chamber of a plasma accelerator and the expansion chamber in an electromagnetic shock tube, does not increase the velocity of the plasma stream front in the expansion chamber, but increases the rate of formation of the luminous body and the yield of optical emission. Reduction of the pressure gradient,

Iu. G. Basov; V. I. Roldugin; V. V. Sysun

1982-01-01

237

Photoionization detector for the detection of xenon light  

Microsoft Academic Search

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.

1980-01-01

238

Design and Performance of Liquid Xenon Detectors for PET  

Microsoft Academic Search

This work is aimed at developing liquid xenon (LXe) detectors for applications to positron emission tomography (PET). The advantages of LXe for PET compared to currently used methods include improved energy resolution by combining information from measuring the ionization as well as the scintillation light, 3-D sub-mm spatial resolution, and Compton scattering reconstruction. Results obtained for the energy resolution with

Astrid Muennich; Pierre Amaudruz; Douglas Bryman; Leonid Kurchaninov; Philip Lu; Cam Marshall; Jean Pierre Martin; Fabrice Retiere; Aleksey Sher

2009-01-01

239

Experimental study of a liquid Xenon PET prototype module  

Microsoft Academic Search

A detector using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the LXe. It does feature a promising solution insensitive to any parallax effect. This work reports on the spatial resolution capabilities of the first LXe prototype module, equipped with a Position Sensitive Photo-Multiplier Tube

M.-L. Gallin-Martel; Ph. Martin; F. Mayet; J. Ballon; G. Barbier; C. Barnoux; J. Berger; D. Bondoux; O. Bourrion; J. Collot; D. Dzahini; R. Foglio; L. Gallin-Martel; A. Garrigue; S. Jan; P. Petit; P. Stassi; F. Vezzu; E. Tournefier

2006-01-01

240

Scintillation efficiency of nuclear recoil in liquid xenon  

Microsoft Academic Search

We present the results of a test done with a Liquid Xenon (LXe) detector for “Dark Matter” search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated by WIMP's elastic scattering. The aim of the experiment was to measure directly the scintillation efficiency of nuclear recoil. The nuclear recoil considered in the test

F. Arneodo; B. Baiboussinov; A. Badertscher; P. Benetti; E. Bernardini; A. Bettini; A Borio di Tiogliole; R. Brunetti; A. Bueno; E. Calligarich; M. Campanelli; C. Carpanese; D. Cavalli; F. Cavanna; P. Cennini; S. Centro; A. Cesana; D. Cline; I De Mitri; R. Dolfini; A. Ferrari; A Gigli Berzolari; C. Matthey; F. Mauri; D. Mazza; L. Mazzone; G. Meng; C. Montanari; G. Nurzia; S. Otwinowski; O. Palamara; D. Pascoli; A. Pepato; S. Petrera; L. Periale; G Piano Mortari; A. Piazzoli; P. Picchi; F. Pietropaolo; T. Rancati; A. Rappoldi; G. L Raselli; D. Rebuzzi; J. P Revo; J. Rico; M. Rossella; C. Rossi; A. Rubbia; C. Rubbia; P. Sala; D. Scannicchio; F. Sergiampietri; S. Suzuki; M. Terrani; W. Tian; S. Ventura; C. Vignoli; H. Wang; J. Woo; Z. Xu

2000-01-01

241

The polarization sensitivity of the liquid xenon imaging telescope  

Microsoft Academic Search

The properties and the expected performance of a liquid xenon (LXe) gamma ray imaging telescope, optimized for the MeV energy region, are presented. The unique potential of this telescope as a Compton polarimeter is particularly emphasized. Based on Monte Carlo simulations we show that the modulation factor is as high as 40 percent at 1 MeV with a detection efficiency

Elena Aprile; A. Bolotnikov; D. Chen; R. Mukherjee

1993-01-01

242

Scintillation e$ciency of nuclear recoil in liquid xenon  

Microsoft Academic Search

We present the results of a test done with a Liquid Xenon (LXe) detector for 'Dark Mattera search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated by WIMP's elastic scattering. The aim of the experiment was to measure directly the scintillation e$ciency of nuclear recoil. The nuclear recoil considered in the test

F. Arneodo; B. Baiboussinov; A. Badertscher; P. Benetti; E. Bernardini; A. Bettini; A. Borio; R. Brunetti; A. Bueno; E. Calligarich; M. Campanelli; C. Carpanese; D. Cavalli; F. Cavanna; P. Cennini; A. Cesana; D. Cline; I. De Mitri; R. Dol; A. Ferrari; A. Gigli Berzolari; C. Matthey; F. Mauri; D. Mazza; L. Mazzone; G. Meng; C. Montanari; G. Nurzia; S. Otwinowski; O. Palamara; D. Pascoli; A. Pepato; S. Petrera; L. Periale; G. Piano Mortari; A. Piazzoli; P. Picchi; F. Pietropaolo; T. Rancati; A. Rappoldi; G. L. Raselli; D. Rebuzzi; J. Rico; M. Rossella; C. Rossi; A. Rubbia; C. Rubbia; P. Sala; D. Scannicchio; F. Sergiampietri; S. Suzuki; M. Terrani; W. Tian; S. Ventura; C. Vignoli; H. Wang; J. Woo; Z. Xu

243

Liquid\\/solid\\/dual phase xenon gamma-ray detectors  

Microsoft Academic Search

It is recognized by various groups in the world that liquid xenon (LXe) is an interesting medium for the detection of gamma-rays. In spite of all the experimental and theoretical effort expended during recent years, the processes that take place in this medium are not yet fully understood. We have obtained some preliminary results using an ionization chamber with a

R. van Sonsbeek; V. R. Bom; C. W. E. van Eijk; R. W. Hollander; K. Meijvogel; W. J. C. Okx

1994-01-01

244

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

245

Avalanche Photodiode for liquid xenon scintillation: quantum efficiency and gain  

Microsoft Academic Search

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 alpha-source in LXe was 5.3 × 103. Based on the geometry of the setup, the quantum efficiency

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

2009-01-01

246

Fast gradient-encoded CEST spectroscopy of hyperpolarized xenon.  

PubMed

Breaking speed limits: The acquisition of xenon-129 Hyper-CEST spectra is drastically accelerated by utilizing gradients to encode the chemical shift dimension. The signal is increased by using repeated spin-echo refocussing. The additional application of a variable flip angle makes the experiment independent from a constant Xe redelivery. PMID:24408772

Döpfert, Jörg; Witte, Christopher; Schröder, Leif

2014-02-01

247

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

Frédéric Hourdin; J.-P. Issartel

2000-01-01

248

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 50°K in the region from 1600 to 900 Å (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

249

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

E-print Network

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 discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

J. Kathawa; C. Fry; M. Thoennessen

2012-01-20

250

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

SciTech Connect

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., E-mail: thoennessen@nscl.msu.edu

2013-01-15

251

NASA's Evolutionary Xenon Thruster (NEXT) Ion Propulsion System Information Summary  

NASA Technical Reports Server (NTRS)

This document is a guide to New Frontiers mission proposal teams. The document describes the development and status of the NASA's Evolutionary Xenon Thruster (NEXT) ion propulsion system (IPS) technology, its application to planetary missions, and the process anticipated to transition NEXT to the first flight mission.

Pencil, Eirc S.; Benson, Scott W.

2008-01-01

252

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

253

Test of a two-dimensional liquid xenon TPC  

Microsoft Academic Search

The spatial resolution of a liquid xenon ionization chamber operated in the time projection mode was measured with a multiwire anode structure, using cosmic rays traversing a maximum drift gap of 5.9 cm. From the digitized pulse shape of the ionization signal induced on the anode wires, the timing information was measured for different track orientations in space. In order

E. Aprile; D. Chen; M. Moulson; R. Mukherjee; M. Suzuki

1992-01-01

254

Pulsed xenon flashlamp device for the treatment of psoriasis  

NASA Astrophysics Data System (ADS)

We present our research into a pulsed xenon lamp source for the treatment of psoriasis and other skin disorders. Various filtering techniques, lamp configurations, power supply configurations and delivery systems are discussed. Comparisons are made to existing treatment modalities. Cryogen cooling of the treatment site is discussed.

Baumgardner, Jonathan M.; Hennings, David R.; Johnston, Thomas F., Jr.; Taylor, Eric

2003-06-01

255

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid...

Giboni, K L; Choi, B; Haruyama, T; Lang, R F; Lim, K E; Melgarejo, A J; Plante, G; 10.1088/1748-0221/6/03/P03002

2011-01-01

256

Xenon Sputter Yield Measurements for Ion Thruster Materials  

Microsoft Academic Search

In this paper, we describe a technique that was used to measure total and differential sputter yields of materials important to high specific impulse ion thrusters. The heart of the technique is 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. Differential sputtering

John D. Williams; Michael M. Gardner; Mark L. Johnson; Paul J. Wilbur

2003-01-01

257

The effect of nitrogen on xenon ion engine erosion  

NASA Technical Reports Server (NTRS)

Erosion studies were performed on a 30-cm diameter J-series ion engine modified for operation on xenon propellant. The erosion rates of molybdenum and tantalum badges placed at different locations within the discharge chamber were measured as a function of the percentage of nitrogen (by mass) added to the xenon propellant. Reductions in the erosion rates of these badges of a factor of 8 to 50 were observed at nitrogen addition fractions between 0.5 to 2.0 percent. Reductions in cathode-side baffle erosion were achieved by adding nitrogen to the xenon propellant or by increasing the cathode orifice diameter. Analyses show that no significant degradation in ion engine performance should be expected at these nitrogen mass fractions. XRD, XPS and Auger analyses indicate the existence of nitrogen and nitrides in the surface of some but not all of the badges used in the tests where nitrogen was added to the xenon. Difficulty in identifying surface nitrides in the samples may be due to the existence of surface oxides and contaminants, or to the small thicknesses of the nitride layers.

Garner, Charles E.; Brophy, John R.; Pless, L. C.; Barnett, John W.

1990-01-01

258

Extrinsic photoconductivity in xenon-doped fluid argon and krypton  

NASA Astrophysics Data System (ADS)

Monochromated synchrotron radiation from the DORIS storage ring at DESY was used to excite photoconduction in xenon-doped fluid argon for densities ranging from 0.7 × 10 22 to 2.1 × 10 22 cm -3, in xenon-doped fluid krypton from 1.3 × 10 22 to 1.6 × 10 22 cm -3 as well as in solid Xe/Ar. The measurements yielded directly the ionization energy E Gi of the impurity in the dense medium. Using previous experimental results on the energy V0 of the conduction electron in conjunction with E Gi the polarization energy P+i of a hole trapped at a xenon atom was also determined for the respective density ranges. These experimental P+i values do not agree with theoretical predictions. Combining the E Gi values with results from absorption spectra by Messing et al. led to the determination of the binding energy and effective mass of the Wannier—Mott impurity exciton and indicated that previous assignments of absorption bands in xenon-doped solid argon have to be revised.

Reininger, R.; Steinberger, I. T.; Bernstorff, S.; Saile, V.; Laporte, P.

259

Polaron theory of positronium localization and annihilation in xenon  

Microsoft Academic Search

We investigate the quantum states of a light particle (positronium, or Ps) in a disordered medium (fluid xenon). The Ps atom is modeled as a hard sphere which has thermalized in a Lennard-Jones fluid. The purpose of this paper is threefold: first, to test the efficacy of a recent analytic theory by comparing its predictions with available results of path-integral

Jiqiang Chen; Bruce N. Miller

1994-01-01

260

Charmonium molecules?  

SciTech Connect

In this talk we present some recent studies of multiquark components in the charmonium sector. We study the possible existence of compact four quark-states and meson-meson molecules in the charmonium spectroscopy.

Valcarce, A.; Fernandez-Carames, T. [Departamento de Fisica Fundamental, Universidad de Salamanca, Salamanca (Spain); Vijande, J. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Valencia (UV) and IFIC (UV-CSIC), Valencia (Spain)

2010-08-05

261

Walking Molecules   

E-print Network

Inspired by the motor protein kinesin, an ambitious and unprecedented mimic is proposed – a synthetic molecular motor that can walk. This thesis aims to explain the basic principles which define such walking molecules, ...

Symes, Mark D

2009-01-01

262

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

263

Carbon dioxide conversion over carbon-based nanocatalysts.  

PubMed

The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity. PMID:23901504

Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

2013-07-01

264

A coherent understanding of low-energy nuclear recoils in liquid xenon  

SciTech Connect

Liquid xenon detectors such as XENON10 and XENON100 obtain a significant fraction of their sensitivity to light (?<10 GeV) particle dark matter by looking for nuclear recoils of only a few keV, just above the detector threshold. Yet in this energy regime a correct treatment of the detector threshold and resolution remains unclear. The energy dependence of the scintillation yield of liquid xenon for nuclear recoils also bears heavily on detector sensitivity, yet numerous measurements have not succeeded in obtaining concordant results. In this article we show that the ratio of detected ionization to scintillation can be leveraged to constrain the scintillation yield. We also present a rigorous treatment of liquid xenon detector threshold and energy resolution. Notably, the effective energy resolution differs significantly from a simple Poisson distribution. We conclude with a calculation of dark matter exclusion limits, and show that existing data from liquid xenon detectors strongly constrain recent interpretations of light dark matter.

Sorensen, Peter, E-mail: pfs@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States)

2010-09-01

265

Detection of liquid xenon scintillation light with a Silicon Photomultiplier  

E-print Network

We have studied the feasibility of a silicon photomultiplier (SiPM) to detect liquid xenon (LXe) scintillation light. The SiPM was operated inside a small volume of pure LXe, at -95 degree Celsius, irradiated with an internal Am-241 alpha source. The gain of the SiPM at this temperature was estimated to be 1.8 x 10^6 with bias voltage at 52 V. Based on the geometry of the setup, the quantum efficiency of the SiPM was estimated to be 22% at the Xe wavelength of 178 nm. The low excess noise factor, high single photoelectron detection efficiency, and low bias voltage of SiPMs make them attractive alternative UV photon detection devices to photomultiplier tubes (PMTs) for liquid xenon detectors, especially for experiments requiring a very low energy detection threshold, such as neutralino dark matter searches.

Aprile, E; Ni, K; Shagin, P

2006-01-01

266

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

267

Gamma Ray Spectroscopy with Scintillation Light in Liquid Xenon  

E-print Network

Scintillation light from gamma ray irradiation in liquid xenon is detected by two Hamamatsu R9288 photomultiplier tubes (PMTs) immersed in the liquid. UV light reflector material, PTFE, is used to optimize the light collection efficiency. The detector gives a high light yield of 6 photoelectron per keV (pe/keV), which allows efficient detection of the 122 keV gamma-ray line from Co-57, with a measured energy resolution of (8.8+/-0.6)% (sigma). The best achievable energy resolution, by removing the instrumental fluctuations, from liquid xenon scintillation light is estimated to be around 6-8% (sigma) for gamma-ray with energy between 662 keV and 122 keV.

K. Ni; E. Aprile; K. L. Giboni; P. Majewski; M. Yamashita

2006-08-04

268

Theoretical study of xenon adsorption in UO2 nanoporous matrices.  

PubMed

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour. PMID:25388362

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

269

Theoretical study of xenon adsorption in UO2 nanoporous matrices  

NASA Astrophysics Data System (ADS)

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour.

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

270

Measurements of proportional scintillation in liquid xenon using thin wires  

E-print Network

Proportional scintillation in liquid xenon has a promising application in the field of direct dark matter detection, potentially allowing for simpler, more sensitive detectors. However, knowledge of the basic properties of the phenomenon as well as guidelines for its practical use are currently limited. We report here on measurements of proportional scintillation light emitted in liquid xenon around thin wires. The maximum proportional scintillation gain of $287^{+97}_{-75}$ photons per drift electron was obtained using 10 $\\mu$m diameter gold plated tungsten wire. The thresholds for electron multiplication and proportional scintillation are measured as $725^{+48}_{-139}$ and $412^{+10}_{-133}$ kV/cm, respectively. The threshold for proportional scintillation is in good agreement with a previously published result, while the electron multiplication threshold represents a novel measurement. A complete set of parameters for the practical use of the electron multiplication and proportional scintillation processe...

Aprile, E; Goetzke, L W; Fernandez, A J Melgarejo; Messina, M; Naganoma, J; Plante, G; Rizzo, A; Shagin, P; Wall, R

2014-01-01

271

Detection of liquid xenon scintillation light with a Silicon Photomultiplier  

E-print Network

We have studied the feasibility of a silicon photomultiplier (SiPM) to detect liquid xenon (LXe) scintillation light. The SiPM was operated inside a small volume of pure LXe, at -95 degree Celsius, irradiated with an internal Am-241 alpha source. The gain of the SiPM at this temperature was estimated to be 1.8 x 10^6 with bias voltage at 52 V. Based on the geometry of the setup, the quantum efficiency of the SiPM was estimated to be 22% at the Xe wavelength of 178 nm. The low excess noise factor, high single photoelectron detection efficiency, and low bias voltage of SiPMs make them attractive alternative UV photon detection devices to photomultiplier tubes (PMTs) for liquid xenon detectors, especially for experiments requiring a very low energy detection threshold, such as neutralino dark matter searches.

E. Aprile; P. Cushman; K. Ni; P. Shagin

2005-01-03

272

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

273

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

274

Experimental investigations of argon and xenon ion sources  

NASA Technical Reports Server (NTRS)

The multipole thruster was used to investigate the use of argon and xenon propellants as possible alternatives to the electric thruster propellants of mercury and cesium. The multipole approach was used because of its general high performance level. The design employed, using flat and cylindrical rolled sections of sheet metal, was selected for ease of fabrication, design, assembly, and modification. All testing was conducted in a vacuum facility and the pumping was accomplished by a 0.8 m diffusion pump together with liquid nitrogen cooled liner. Minimum discharge losses were in the 200-250 ev. ion range for both argon and xenon. Flatness parameters were typically in the 0.70-0.75 range.

Kaufman, H. R.

1975-01-01

275

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

276

Development of liquid xenon detectors for gamma ray astronomy  

NASA Technical Reports Server (NTRS)

The application of liquid xenon in high-resolution detectors for gamma-ray astronomy is being investigated. Initial results from a pulse-shape analysis of ionization signals in a liquid-xenon gridded chamber indicate that it is possible to achieve the necessary liquid purity for the transport of free electrons with simple techniques. The energy resolution has been measured as a function of applied electric field, using electrons and gamma-rays from a 207Bi source. At a field of 12 kV/cm the noise-substracted energy resolution of the dominant 569-keV gamma-ray line is 34 keV FWHM (full width at half maximum). This value is mostly determined by recombination of electron-ion pairs on delta-electron tracks.

Aprile, Elena; Suzuki, Masayo

1989-01-01

277

Carbon Dioxide Exercise  

NSDL National Science Digital Library

In this activity, students work in groups, plotting carbon dioxide concentrations over time on overheads and estimating the rate of change over five years. Stacked together, the overheads for the whole class show an increase on carbon dioxide over five years and annual variation driven by photosynthesis. This exercise enables students to practice basic quantitative skills and understand how important sampling intervals can be when studying changes over time. A goal is to see how small sample size may give incomplete picture of data.

Richardson, Randy; Collection, Serc -.

278

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

Microsoft Academic Search

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

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

2008-01-01

279

EUV emission from xenon in the 1080 nm wavelength range using a compact ECR ion source  

E-print Network

EUV emission from xenon in the 10­80 nm wavelength range using a compact ECR ion source H. Merabet is assignment of numerous new optical transitions for xenon in the 10­80 nm range to create a database. PACS: 32.30.�r; 32.30.Jc; 32.70.�n; 32.70.Fw Keywords: EUV emission; Xenon atomic spectra; 13.4 nm

Godunov, Alexander L.

280

Krypton assay in xenon at the ppq level using a gas chromatographic system and mass spectrometer  

NASA Astrophysics Data System (ADS)

We have developed a new method to measure krypton traces in xenon at unprecedented low concentrations. This is a mandatory task for many near-future low-background particle physics detectors. Our system separates krypton from xenon using cryogenic gas chromatography. The amount of krypton is then quantified using a mass spectrometer. We demonstrate that the system has achieved a detection limit of 8 ppq (parts per quadrillion) and present results of distilled xenon with krypton concentrations below 1 ppt.

Lindemann, Sebastian; Simgen, Hardy

2014-02-01

281

Development of a high-resolution liquid xenon detector for gamma-ray astrophysics  

Microsoft Academic Search

It has been shown here that liquid xenon is one of the most promising detector media for future gamma-ray detectors, owing to an excellent combination of physical properties. The feasibility of the construction of a high resolution liquid xenon detector as a gamma-ray detector for astrophysics has been demonstrated. Up to 3.5 liters of liquid xenon has been successfully purified

Reshmi Mukherjee

1993-01-01

282

CMD3 liquid xenon calorimeter's signals processing for timing measurements  

Microsoft Academic Search

One of the goals of the Cryogenic Magnetic Detector (CMD-3) experiment (Budker Institute of Nuclear Physics, Novosibirsk, Russia) is a study of the nucleon birth reactions near threshold in electron-positron annihilation. An important example of such process is a neutron-antineutron pair production. A signature of this process is a large energy deposition in the liquid xenon (LXe) -calorimeter due to

L. B. Epshteyn; Yu. V. Yudin

2011-01-01

283

The polarization sensitivity of the liquid xenon imaging telescope  

Microsoft Academic Search

The properties and the expected performance of a liquid xenon (LXe) gamma-ray imaging telescope, optimized for the MeV energy region, are presented. The unique potential of this telescope as a Compton polarimeter is particularly emphasized. Based on Monte Carlo simulations, we show that the modulation factor is as high as 40% at 1 MeV with a detection efficiency close to

E. Aprile; A. Bolotnikov; D. Chen; R. Mukherjee; F. Xu

1994-01-01

284

Scintillation response of liquid xenon to low energy nuclear recoils  

Microsoft Academic Search

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from C57o. The scintillation yield of 56.5 keV

E. Aprile; K. L. Giboni; P. Majewski; K. Ni; M. Yamashita; R. Hasty; A. Manzur; D. N. McKinsey

2005-01-01

285

Performance of the liquid xenon detector for the MEG experiment  

NASA Astrophysics Data System (ADS)

A 900-l liquid xenon (LXe) detector was constructed for the MEG experiment to look for ?+?e+?. With proper calibration and monitoring the detector was successfully operated during the first physics data taking for three months in 2008. We evaluated the performance of the LXe detector around the signal-? energy of 52.8 MeV by using 54.9-MeV photons obtained from ?0 decays.

Nishimura, Yasuhiro; Natori, Hiroaki; MEG Collaboration

2011-02-01

286

Performance of the liquid xenon detector for the MEG experiment  

Microsoft Academic Search

A 900-l liquid xenon (LXe) detector was constructed for the MEG experiment to look for ?+?e+?. With proper calibration and monitoring the detector was successfully operated during the first physics data taking for three months in 2008. We evaluated the performance of the LXe detector around the signal-? energy of 52.8MeV by using 54.9-MeV photons obtained from ?0 decays.

Yasuhiro Nishimura; Hiroaki Natori

2011-01-01

287

Experimental study of a liquid Xenon PET prototype module  

NASA Astrophysics Data System (ADS)

A detector using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the LXe. It does feature a promising solution insensitive to any parallax effect. This work reports on the spatial resolution capabilities of the first LXe prototype module, equipped with a Position Sensitive Photo-Multiplier Tube (PSPMT) operating in the VUV range (178 nm).

Gallin-Martel, M.-L.; Martin, Ph.; Mayet, F.; Ballon, J.; Barbier, G.; Barnoux, C.; Berger, J.; Bondoux, D.; Bourrion, O.; Collot, J.; Dzahini, D.; Foglio, R.; Gallin-Martel, L.; Garrigue, A.; Jan, S.; Petit, P.; Stassi, P.; Vezzu, F.; Tournefier, E.

2006-07-01

288

Light yield of liquid and solid xenon irradiated with ?-rays  

Microsoft Academic Search

We have measured the absolute light yield of liquid and solid xenon (LXe and SXe respectively) irradiated with ?-rays with energies from 320 keV to 1770 keV. With our method, which consisted of comparing the light yield of LXeSXe with that of BaF2, we found a value of (24±3)×103 photons\\/MeV. This means we estimate the Ws-value to be (42±6) eV.

R. van Sonsbeek; C. W. E. van Eijk; R. W. Hollander

1995-01-01

289

Design and Performance of Liquid Xenon Detectors for PET  

NASA Astrophysics Data System (ADS)

This work is aimed at developing liquid xenon (LXe) detectors for applications to positron emission tomography (PET). The advantages of LXe for PET compared to currently used methods include improved energy resolution by combining information from measuring the ionization as well as the scintillation light, 3-D sub-mm spatial resolution, and Compton scattering reconstruction. Results obtained for the energy resolution with a small prototype and an analysis of error sources will be presented.

Muennich, Astrid; Amaudruz, Pierre; Bryman, Douglas; Kurchaninov, Leonid; Lu, Philip; Marshall, Cam; Martin, Jean Pierre; Retiere, Fabrice; Sher, Aleksey

2009-05-01

290

Quench gases for xenon- (and krypton-) filled proportional counters  

NASA Technical Reports Server (NTRS)

Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

Ramsey, B. D.; Agrawal, P. C.

1988-01-01

291

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

292

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

293

Neutrino physics with multi-ton scale liquid xenon detectors  

NASA Astrophysics Data System (ADS)

We study the sensitivity of large-scale xenon detectors to low-energy solar neutrinos, to coherent neutrino-nucleus scattering and to neutrinoless double beta decay. As a concrete example, we consider the xenon part of the proposed DARWIN (Dark Matter WIMP Search with Noble Liquids) experiment. We perform detailed Monte Carlo simulations of the expected backgrounds, considering realistic energy resolutions and thresholds in the detector. In a low-energy window of 2–30 keV, where the sensitivity to solar pp and 7Be-neutrinos is highest, an integrated pp-neutrino rate of 5900 events can be reached in a fiducial mass of 14 tons of natural xenon, after 5 years of data. The pp-neutrino flux could thus be measured with a statistical uncertainty around 1%, reaching the precision of solar model predictions. These low-energy solar neutrinos will be the limiting background to the dark matter search channel for WIMP-nucleon cross sections below ~ 2 × 10?48 cm2 and WIMP masses around 50 GeV?c?2, for an assumed 99.5% rejection of electronic recoils due to elastic neutrino-electron scatters. Nuclear recoils from coherent scattering of solar neutrinos will limit the sensitivity to WIMP masses below ~ 6 GeV?c?2 to cross sections above ~ 4 × 10?45cm2. DARWIN could reach a competitive half-life sensitivity of 5.6 × 1026 y to the neutrinoless double beta decay of 136Xe after 5 years of data, using 6 tons of natural xenon in the central detector region.

Baudis, L.; Ferella, A.; Kish, A.; Manalaysay, A.; Marrodán Undagoitia, T.; Schumann, M.

2014-01-01

294

Neutrino physics with multi-ton scale liquid xenon detectors  

E-print Network

We study the sensitivity of large-scale xenon detectors to low-energy solar neutrinos, to coherent neutrino-nucleus scattering and to neutrinoless double beta decay. As a concrete example, we consider the xenon part of the proposed DARWIN (Dark Matter WIMP Search with Noble Liquids) experiment. We perform detailed Monte Carlo simulations of the expected backgrounds, considering realistic energy resolutions and thresholds in the detector. In a low-energy window of 2-30 keV, where the sensitivity to solar pp and $^7$Be-neutrinos is highest, an integrated pp-neutrino rate of 5900 events can be reached in a fiducial mass of 14 tons of natural xenon, after 5 years of data. The pp-neutrino flux could thus be measured with a statistical uncertainty around 1%, reaching the precision of solar model predictions. These low-energy solar neutrinos will be the limiting background to the dark matter search channel for WIMP-nucleon cross sections below $\\sim$2$\\times$10$^{-48}$ cm$^2$ and WIMP masses around 50 GeV$\\cdot$c$^{-2}$, for an assumed 99.5% rejection of electronic recoils due to elastic neutrino-electron scatters. Nuclear recoils from coherent scattering of solar neutrinos will limit the sensitivity to WIMP masses below $\\sim$6 GeV$\\cdot$c$^{-2}$ to cross sections above $\\sim$4$\\times$10$^{-45}$cm$^2$. DARWIN could reach a competitive half-life sensitivity of 5.6$\\times$10$^{26}$ y to the neutrinoless double beta decay of $^{136}$Xe after 5 years of data, using 6 tons of natural xenon in the central detector region.

L. Baudis; A. Ferella; A. Kish; A. Manalaysay; T. Marrodan Undagoitia; M. Schumann

2014-02-07

295

Biological Molecules  

NSDL National Science Digital Library

Paul Anderson describes the four major biological molecules found in living things. He begins with a brief discussion of polymerization. Dehydration synthesis is used to connect monomers into polymers and hydrolysis breaks them down again. The major characteristics of nucleic acids are described as well as there directionality from 3' to 5' end.

Anderson, Paul

2013-03-12

296

A Comprehensive Study of the Large Underground Xenon Detector  

NASA Astrophysics Data System (ADS)

The Large Underground Xenon (LUX) dark matter search experiment operates a time projection chamber constructed of 370 kg of xenon, currently installed in the Homestake gold mine. The goal of the experiment is to detect Weakly Interacting Massive Particles (WIMPs). Novel calibration methods for this uniquely large detector are discussed. Background events due to standard model physics processes including cosmogenically activated xenon, alpha emission, and neutron production are shown to be negligible in recent 85 day WIMP search data. The LUX Monte Carlo simulation includes a new physical model, the Nobel Element Simulation Technique (NEST), for scintillation and ionization. NEST describes energy-, particle-, field- and medium-dependent behavior of a charge recombination model. A simulated data acquisition chain that bridges the gap between simulation and data has been developed to permit full testing of the analysis tools employed by LUX. Signal generation by cumulative photon responses are described algorithmically. Computational optimization has been performed to decrease processing time by a factor of fifty. A new technique for event depth estimation using machine learning and image analysis is introduced. Variable length waveforms are converted to fixed dimension field maps for use in machine learning. A support vector machine trained against pulse shapes with known depth successfully regressed depth without direct measurement of highly variable pulse widths. The world's most stringent limits on spin-independent WIMP-nucleon scattering cross section are presented.

Woods, Michael Austin

297

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

298

Very-low-field MRI of laser polarized xenon-129  

NASA Astrophysics Data System (ADS)

We describe a homebuilt MRI system for imaging laser-polarized xenon-129 at a very low holding field of 2.2 mT. A unique feature of this system was the use of Maxwell coils oriented at so-called "magic angles" to generate the transverse magnetic field gradients, which provided a simple alternative to Golay coils. We used this system to image a laser-polarized xenon-129 phantom with both a conventional gradient-echo and a fully phase-encoded pulse sequence. In other contexts, a fully phase-encoded acquisition, also known as single-point or constant-time imaging, has been used to enable distortion-free imaging of short- T 2 ? species. Here we used this technique to overcome imperfections associated with our homebuilt MRI system while also taking full advantage of the long T 2 ? available at very low field. Our results demonstrate that xenon-129 image quality can be dramatically improved at low field by combining a fully phase-encoded k-space acquisition with auxiliary measurements of system imperfections including B0 field drift and gradient infidelity.

Zheng, Yuan; Cates, Gordon D.; Tobias, William A.; Mugler, John P.; Miller, G. Wilson

2014-12-01

299

Allende meteorite: Isotopically anomalous xenon is accompanied by normal osmium  

PubMed Central

The 184Os/190Os ratio of six Allende meteorite samples was determined by neutron activation analysis. Four chromite concentrates gave a ratio differing from the terrestrial ratio by only -0.1 ± 0.4%, although they contained highly anomalous xenon enriched by up to 67% in 124Xe and 93% in 136Xe. In view of this result and the normal isotopic composition of carbon and oxygen in these fractions, it seems very unlikely that the xenon anomalies were produced in a supernova by the p and r processes. More probably, the xenon anomalies were established in the early solar system, by mass fractionation during trapping of noble gases in solids and by spontaneous fission of a superheavy element. Two other samples, containing osmium from the calcium,aluminum-rich inclusions, also gave an 184Os/190Os ratio within -0.1 ± 0.5% of the terrestrial value, although these inclusions show well-established anomalies in the light elements oxygen and magnesium, which appear to be due to pre-solar dust grains of distinctive nuclear history. Apparently the stellar source of the anomalous oxygen and magnesium did not synthesize heavier elements. PMID:16592365

Takahashi, H.; Higuchi, H.; Gros, Jacques; Morgan, John W.; Anders, Edward

1976-01-01

300

High-pressure xenon detector development at Constellation Technology Corporation  

NASA Astrophysics Data System (ADS)

Xenon-filled ionization detectors, due to their high atomic number fill gas ( Z=54), moderate densities (˜0.3-0.5 g/cm 3) and good energy resolution (2-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and germanium detectors. Until recently, difficulties with obtaining sufficient xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990s, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Current applications for Constellation's detectors are principally in the area of defense (Unmanned Aerial Vehicles and Advanced Spectroscopic Portals), but as awareness of this technology grows, it will surely find applications in a much expanded range of fields.

Austin, Robert A.

2007-08-01

301

Very-low-field MRI of laser polarized xenon-129.  

PubMed

We describe a homebuilt MRI system for imaging laser-polarized xenon-129 at a very low holding field of 2.2mT. A unique feature of this system was the use of Maxwell coils oriented at so-called "magic angles" to generate the transverse magnetic field gradients, which provided a simple alternative to Golay coils. We used this system to image a laser-polarized xenon-129 phantom with both a conventional gradient-echo and a fully phase-encoded pulse sequence. In other contexts, a fully phase-encoded acquisition, also known as single-point or constant-time imaging, has been used to enable distortion-free imaging of short-T2(?) species. Here we used this technique to overcome imperfections associated with our homebuilt MRI system while also taking full advantage of the long T2(?) available at very low field. Our results demonstrate that xenon-129 image quality can be dramatically improved at low field by combining a fully phase-encoded k-space acquisition with auxiliary measurements of system imperfections including B0 field drift and gradient infidelity. PMID:25462954

Zheng, Yuan; Cates, Gordon D; Tobias, William A; Mugler, John P; Miller, G Wilson

2014-10-17

302

Calibration of a Two Phase Liquid Xenon Time Projection Chamber with Kr-83m  

E-print Network

We report the testing of a charcoal based Kr-83m source for use in calibrating a low-background two-phase liquid xenon detector. Kr-83m atoms produced through the decay of Rb-83 are introduced into a xenon detector by flowing xenon gas past the Rb-83 source. 9.4 keV and 32.1 keV conversion electrons from decaying Kr-83m nuclei are detected through liquid xenon scintillation and ionization. Introduction of Kr-83m allows for quick, periodic calibration of low background noble liquid detectors at low energy.

Kastens, L W; Cahn, S B; Manzur, A; McKinsey, D N

2009-01-01

303

Light-induced, site-selective isomerization of glyoxylic acid in solid xenon  

NASA Astrophysics Data System (ADS)

The isomerization of glyoxylic acid (GA) and its water complex was studied in a low temperature xenon matrix. The aim of these studies was to understand how xenon environment affects the cis-trans GA interconversion upon near infrared irradiation. In solid xenon, the GA conformers are embedded in two different matrix sites. These show up as different vibrational bands of GA that exhibit different kinetic rates of isomerization. Upon complexation with water, the isomerization process slows down. Xenon matrix appears not to affect energy relaxation process via intramolecular or intermolecular hydrogen bond as compared with previous experiments in an argon.

Olbert-Majkut, Adriana; Wierzejewska, Maria; Lundell, Jan

2014-11-01

304

Early outgassing of Mars supported by differential water solubility of iodine and xenon  

NASA Technical Reports Server (NTRS)

The Martian atmosphere has a high X-129/Xe-132 ratio compared to the Martian mantle. As Xe-129 is the daughter product of the extinct nuclide I-129, a means of fractionating iodine from xenon early in Martian history appears necessary to account for the X-129/Xe-132 ratios of its known reservoirs. A model is presented here to account for the Marian xenon data which relies on the very different solubilities of xenon and iodine in water to fractionate them after outgassing. Atmospheric xenon is lost by impact erosion during heavy bombardment, followed by release of Xe-129 produced from I-129 decay in the crust.

Musselwhite, Donald S.; Drake, Michael J.; Swindle, Timothy D.

1991-01-01

305

The KrXe molecule: Modification of potential curves of the ground and first excited electronic states  

NASA Astrophysics Data System (ADS)

Potential curves of the ground state of the KrXe molecule and its excited states that converge to the Kr(4 p 6 1 S 0) + Xe(5 p 56 s 3 P 1) atomic states are corrected and tested using the results of modeling published vacuum ultraviolet spectra of a gas-discharge plasma of a krypton/xenon mixture.

Loginov, A. V.

2013-09-01

306

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...

307

Carbon Dioxide Laser Guidelines  

PubMed Central

The carbon dioxide (CO2) laser is a versatile tool that has applications in ablative lasing and caters to the needs of routine dermatological practice as well as the aesthetic, cosmetic and rejuvenation segments. This article details the basics of the laser physics as applicable to the CO2 laser and offers guidelines for use in many of the above indications. PMID:20808594

Krupa Shankar, DS; Chakravarthi, M; Shilpakar, Rachana

2009-01-01

308

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

309

Carbon Dioxide Increases  

NSDL National Science Digital Library

In this problem set, learners will analyze the Keeling Curve showing carbon dioxide concentration in the atmosphere since 1985 to answer a series of questions. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

310

Atmospheric Carbon Dioxide  

NSDL National Science Digital Library

This figure, the famous Keeling Curve, shows the history of atmospheric carbon dioxide concentrations as directly measured at Mauna Loa, Hawaii. This curve is an essential piece of evidence that shows the increased greenhouse gases that cause recent increases in global temperatures.

Robert A. Rohde

311

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.

2012-12-26

312

Carbon dioxide sensor  

DOEpatents

The present invention generally relates to carbon dioxide (CO.sub.2) sensors. In one embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor that incorporates lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3). In another embodiment, the present invention relates to a carbon dioxide (CO.sub.2) sensor has a reduced sensitivity to humidity due to a sensing electrode with a layered structure of lithium carbonate and barium carbonate. In still another embodiment, the present invention relates to a method of producing carbon dioxide (CO.sub.2) sensors having lithium phosphate (Li.sub.3PO.sub.4) as an electrolyte and sensing electrode comprising a combination of lithium carbonate (Li.sub.2CO.sub.3) and barium carbonate (BaCO.sub.3).

Dutta, Prabir K. (Worthington, OH); Lee, Inhee (Columbus, OH); Akbar, Sheikh A. (Hilliard, OH)

2011-11-15

313

Diffusion NMR methods applied to xenon gas for materials study  

NASA Technical Reports Server (NTRS)

We report initial NMR studies of (i) xenon gas diffusion in model heterogeneous porous media and (ii) continuous flow laser-polarized xenon gas. Both areas utilize the pulsed gradient spin-echo (PGSE) techniques in the gas phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients--a brief overview of this area is provided in the Introduction. The heterogeneous or multiple-length scale model porous media consisted of random packs of mixed glass beads of two different sizes. We focus on observing the approach of the time-dependent gas diffusion coefficient, D(t) (an indicator of mean squared displacement), to the long-time asymptote, with the aim of understanding the long-length scale structural information that may be derived from a heterogeneous porous system. We find that D(t) of imbibed xenon gas at short diffusion times is similar for the mixed bead pack and a pack of the smaller sized beads alone, hence reflecting the pore surface area to volume ratio of the smaller bead sample. The approach of D(t) to the long-time limit follows that of a pack of the larger sized beads alone, although the limiting D(t) for the mixed bead pack is lower, reflecting the lower porosity of the sample compared to that of a pack of mono-sized glass beads. The Pade approximation is used to interpolate D(t) data between the short- and long-time limits. Initial studies of continuous flow laser-polarized xenon gas demonstrate velocity-sensitive imaging of much higher flows than can generally be obtained with liquids (20-200 mm s-1). Gas velocity imaging is, however, found to be limited to a resolution of about 1 mm s-1 owing to the high diffusivity of gases compared with liquids. We also present the first gas-phase NMR scattering, or diffusive-diffraction, data, namely flow-enhanced structural features in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack. c2002 John Wiley & Sons, Ltd.

Mair, R. W.; Rosen, M. S.; Wang, R.; Cory, D. G.; Walsworth, R. L.

2002-01-01

314

Observing and preventing rubidium runaway in a direct-infusion xenon-spin hyperpolarizer optimized for high-resolution hyper-CEST (chemical exchange saturation transfer using hyperpolarized nuclei) NMR  

SciTech Connect

Xenon is well known to undergo host-guest interactions with proteins and synthetic molecules. As xenon can also be hyperpolarized by spin exchange optical pumping, allowing the investigation of highly dilute systems, it makes an ideal nuclear magnetic resonance probe for such host molecules. The utility of xenon as a probe can be further improved using Chemical Exchange Saturation Transfer using hyperpolarized nuclei (Hyper-CEST), but for highly accurate experiments requires a polarizer and xenon infusion system optimized for such measurements. We present the design of a hyperpolarizer and xenon infusion system specifically designed to meet the requirements of Hyper-CEST measurements. One key element of this design is preventing rubidium runaway, a chain reaction induced by laser heating that prevents efficient utilization of high photon densities. Using thermocouples positioned along the pumping cell we identify the sources of heating and conditions for rubidium runaway to occur. We then demonstrate the effectiveness of actively cooling the optical cell to prevent rubidium runaway in a compact setup. This results in a 2–3-fold higher polarization than without cooling, allowing us to achieve a polarization of 25% at continuous flow rates of 9 ml/min of {sup 129}Xe. The simplicity of this design also allows it to be retrofitted to many existing polarizers. Combined with a direction infusion system that reduces shot-to-shot noise down to 0.56% we have captured Hyper-CEST spectra in unprecedented detail, allowing us to completely resolve peaks separated by just 1.62 ppm. Due to its high polarization and excellent stability, our design allows the comparison of underlying theories of host-guest systems with experiment at low concentrations, something extremely difficult with previous polarizers.

Witte, C.; Kunth, M.; Rossella, F.; Schröder, L., E-mail: lschroeder@fmp-berlin.de [ERC Project BiosensorImaging, Leibniz-Institut für Molekulare Pharmakologie, Berlin (Germany)

2014-02-28

315

Observing and preventing rubidium runaway in a direct-infusion xenon-spin hyperpolarizer optimized for high-resolution hyper-CEST (chemical exchange saturation transfer using hyperpolarized nuclei) NMR  

NASA Astrophysics Data System (ADS)

Xenon is well known to undergo host-guest interactions with proteins and synthetic molecules. As xenon can also be hyperpolarized by spin exchange optical pumping, allowing the investigation of highly dilute systems, it makes an ideal nuclear magnetic resonance probe for such host molecules. The utility of xenon as a probe can be further improved using Chemical Exchange Saturation Transfer using hyperpolarized nuclei (Hyper-CEST), but for highly accurate experiments requires a polarizer and xenon infusion system optimized for such measurements. We present the design of a hyperpolarizer and xenon infusion system specifically designed to meet the requirements of Hyper-CEST measurements. One key element of this design is preventing rubidium runaway, a chain reaction induced by laser heating that prevents efficient utilization of high photon densities. Using thermocouples positioned along the pumping cell we identify the sources of heating and conditions for rubidium runaway to occur. We then demonstrate the effectiveness of actively cooling the optical cell to prevent rubidium runaway in a compact setup. This results in a 2-3-fold higher polarization than without cooling, allowing us to achieve a polarization of 25% at continuous flow rates of 9 ml/min of 129Xe. The simplicity of this design also allows it to be retrofitted to many existing polarizers. Combined with a direction infusion system that reduces shot-to-shot noise down to 0.56% we have captured Hyper-CEST spectra in unprecedented detail, allowing us to completely resolve peaks separated by just 1.62 ppm. Due to its high polarization and excellent stability, our design allows the comparison of underlying theories of host-guest systems with experiment at low concentrations, something extremely difficult with previous polarizers.

Witte, C.; Kunth, M.; Rossella, F.; Schröder, L.

2014-02-01

316

Barium Ion Extraction and Identification from Laser Induced Fluorescence in Gas for the Enriched Xenon Observatory  

NASA Astrophysics Data System (ADS)

The scientific community is increasingly interested in neutrinoless double beta decay. A potential measurement of the decay rate would determine the neutrino mass and would be sensitive to some extensions of the Standard Model of particle physics. Unfortunately, the decay rate is very low and competes with natural and cosmogenic radioactivity. This thesis presents a technique that eliminates such background events. It is performed by observing the barium ion daughter from the double beta decay of xenon-136 using laser induced fluorescence. The technique is very complex and requires an excellent understanding of the barium ion spectroscopy and its chemistry in the vicinity of other molecules. Such a technique will become a unique advantage over other neutrinoless double beta decay experiments, especially if the neutrino mass is low. This thesis describes three main topics. The first one describes simulations of ionizing electrons in xenon to determine the size of a gas phase detector for a neutrinoless double beta decay measurement. It has been determined that a meter size detector would contain most electron tracks. Then, it describes the design of two barium ion sources, one relying on electric discharges across two electrodes and the other one using a high energy pulsed laser. From those sources, the spectroscopy of barium ions was studied. The branching ratio of the 62S1/2 -- ---6 2P1/2 transition was found to be 74 +/- 4%. By adding argon in the chamber, the lineshift of the transition due to collisions was found to be -132 MHz/torr while the broadening rate was 23 MHz/torr. Finally, the most interesting topic is the production of doubly charged barium ions using an electrospray source. From it, ions were extracted to vacuum in a mass spectrometer and charge conversion was achieved using triethylamine. The efficiency of the conversion of Ba+ to Ba ++ was almost 100%, with a cross-section between 1.69 x 10 -18 m2 and 2.21 x 10-18 m 2 without forming any molecules.

Rollin, Etienne

317

Carbon dioxide dangers demonstration model  

USGS Publications Warehouse

Carbon dioxide is a dangerous volcanic gas. When carbon dioxide seeps from the ground, it normally mixes with the air and dissipates rapidly. However, because carbon dioxide gas is heavier than air, it can collect in snowbanks, depressions, and poorly ventilated enclosures posing a potential danger to people and other living things. In this experiment we show how carbon dioxide gas displaces oxygen as it collects in low-lying areas. When carbon dioxide, created by mixing vinegar and baking soda, is added to a bowl with candles of different heights, the flames are extinguished as if by magic.

Venezky, Dina; Wessells, Stephen

2010-01-01

318

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

319

Volume 191, number 5 CHEMICAL PHYSICS LETTERS 10April 1992 Oriented geminate recombination of Cl2 in solid xenon  

E-print Network

in solid xenon at high pressure G.J. Hoffman, E. Sekreta and V.A. Apkarian ' Department of Chemistry emission in CIZ-doped solid xenon under high pressure, in a diamond anvil cell (DAC). The motivation behind

Apkarian, V. Ara

320

Photolytical Generation of Carbon Dioxide  

NASA Astrophysics Data System (ADS)

Carbon dioxide has been found by Cassini VIMS throughout the Saturnian system in locations such as Iapetus' equator where the temperature is too high for it to remain as free ice for more than a few hundred years. We suggest that the 4.26 micron absorption feature found on Iapetus and Hyperion (that has been attributed to complexed CO2) is the result of either UV photolysis or ion bombardment driving chemistry between the carbon rich layer and the water ice regolith. We conducted experiments to simulate the generation of CO2 by UV radiation under conditions similar to those on the surface of Iapetus. A simulated icy regolith was created in an argon atmosphere using flash-frozen, degassed water crushed into sub-millimeter sized particles. Isotopically labeled amorphous carbon (13C), which was ground into a fine dust, was mixed into the regolith allowing for extensive grain contact. This sample was placed in a vacuum chamber and cooled to temperatures as low at 60K. The sample was irradiated with UV light, and the products were measured using both a mass spectrometer to identify free molecules and an IR spectrometer for molecules that remained trapped on and in the simulated regolith. We report on the production and reaction rates of CO2 and CO, as well as the generation of free hydrogen and oxygen as detected by a SRS-100 mass spectrometer. We also identify residual products that either freeze on the surface or become entrained by or adsorbed onto the ice grains. We attempt to match the CO2 absorption feature found on Iapetus with that seen in our simulation, perhaps identifying a possible source of CO2 in the Saturnian system. Finally, we estimate the time required for these reactions to occur on Iapetus to see if UV photolysis would be effective.

Palmer, E. E.; Brown, R. H.

2008-12-01

321

Xenon in and at the End of the Tunnel of Bifunctional Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase†,‡  

PubMed Central

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 Å long) to allow for intermolecular CO transport. Here, we report a 2.5 Å 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. PMID:18293927

Doukov, Tzanko I.; Blasiak, Leah C.; Seravalli, Javier; Ragsdale, Stephen W.; Drennan, Catherine L.

2011-01-01

322

Q4 Consider a model for n identical xenon atoms of mass m that are trapped on the surface of a solid. A xenon atom can be tightly bound to  

E-print Network

Q4 Consider a model for n identical xenon atoms of mass m that are trapped on the surface of a solid. A xenon atom can be tightly bound to one of N adsorption sites with binding energy Ea (a positive it is free to move along the surface, the xenon atom has both kinetic energy mv2 /2 and constant potential

Ha, Taekjip

323

The effects of He addition on the performance of the fission-fragment excited Ar/Xe atomic xenon laser  

E-print Network

The effects of He addition on the performance of the fission-fragment excited Ar/Xe atomic xenon September 1990; accepted for publication 8 November 1990) The intrinsic power efficiency of the atomic xenon of a fission-fragment excited atomic xenon laser. Adding He increases the heat capacity without appreciably

Kushner, Mark

324

"Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" , D B Cline1  

E-print Network

1 "Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" M Atac1 , D B Cline1 , K T Mc in the direct observation of nuclear recoils. The ZEPLIN-II detector (with 35-kg of liquid xenon medium), which. These tests will include: 1. photon amplification in liquid and gas xenon using a CsI internal photo

McDonald, Kirk

325

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b  

E-print Network

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b , Luxi Li a,b , C. M ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical

Findley, Gary L.

326

A liquid xenon PET camera -Simulation and position sensitive PMT tests S.Jan, J.Collot, E Tournefier  

E-print Network

A liquid xenon PET camera - Simulation and position sensitive PMT tests S.Jan, J.Collot, E Abstract A detector which uses liquid xenon in the scintillation mode, is studied for Positron Emission a Positron Emission Tomograph (PET) based on the use of liquid xenon (LXe) as an active medium. This PET

Paris-Sud XI, Université de

327

X-ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann (*) and C. Marti  

E-print Network

1527 X- ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann 1986) Résumé. 2014 En étudiant, par diffraction des rayons X, les mélanges xenon-krypton absorbés sur. Abstract 2014 Mixtures of xenon and krypton adsorbed on graphite at 45 K are studied by X ray diffraction

Boyer, Edmond

328

Stability of xenon oxides at high pressures *, Daniel Y. Jung2, Artem R. Oganov1,3  

E-print Network

Stability of xenon oxides at high pressures Qiang Zhu1 *, Daniel Y. Jung2, Artem R. Oganov1,3 *, Colin W. Glass4, Carlo Gatti5 and Andriy O. Lyakhov1 Xenon, which is quite inert under ambient conditions, may become reactive under pressure. The possibility of the formation of stable xenon oxides

Oganov, Artem R.

329

An improved interatomic potential for xenon in UO2: a combined density functional theory/genetic algorithm approach.  

PubMed

We have created an improved xenon interatomic potential for use with existing UO2 potentials. This potential was fit to density functional theory calculations with the Hubbard U correction (DFT + U) using a genetic algorithm approach called iterative potential refinement (IPR). We examine the defect energetics of the IPR-fitted xenon interatomic potential as well as other, previously published xenon potentials. We compare these potentials to DFT + U derived energetics for a series of xenon defects in a variety of incorporation sites (large, intermediate, and small vacant sites). We find the existing xenon potentials overestimate the energy needed to add a xenon atom to a wide set of defect sites representing a range of incorporation sites, including failing to correctly rank the energetics of the small incorporation site defects (xenon in an interstitial and xenon in a uranium site neighboring uranium in an interstitial). These failures are due to problematic descriptions of Xe-O and/or Xe-U interactions of the previous xenon potentials. These failures are corrected by our newly created xenon potential: our IPR-generated potential gives good agreement with DFT + U calculations to which it was not fitted, such as xenon in an interstitial (small incorporation site) and xenon in a double Schottky defect cluster (large incorporation site). Finally, we note that IPR is very flexible and can be applied to a wide variety of potential forms and materials systems, including metals and EAM potentials. PMID:24553248

Thompson, Alexander E; Meredig, Bryce; Wolverton, C

2014-03-12

330

Precise Attitude Control of All-Electric GEO Spacecraft using Xenon Microthrusters  

E-print Network

Precise Attitude Control of All-Electric GEO Spacecraft using Xenon Microthrusters IEPC-2013- form. The attitude control system is based on cold gas and electrothermal Xenon mi- crothrusters scientific organizations have suffered from budget limitations. As a consequence, commercial platforms

Giannitrapani, Antonello

331

Simulation of a high performance ?-camera concept for PET based on liquid xenon and gaseous photomultiplier  

Microsoft Academic Search

We present the results of GEANT3 simulations of a full PET system made of liquid xenon (LXe)-TPC ?-camera modules. In such camera both ionization and scintillation signals will be detected to provide the three coordinates and the energy of the converted ?-ray. For that purpose, we will develop advanced ionization detectors operating in liquid xenon as well as fast cryogenic

C. Grignon; A. Breskin; T. Carlier; O. Couturier; J. P. Cussonneau; L. Ferrer; L. Luquin; V. Metivier; V. Peskov; F. Pheron; N. Servagent; D. Thers; A. Vasseur

2005-01-01

332

Response of XENON10 to Neutrons: Comparison of Monte Carlo and data  

Microsoft Academic Search

The XENON experiment uses liquid xenon (LXe) as the target medium for detecting Cold Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs). Event by event discrimination is achieved by simultaneously measuring the ionization and scintillation signal produced by nuclear recoil events. The discrimination power is calibrated based on neutron and gamma calibrations done using external AmBe and

Angel Manzur

2007-01-01

333

Collision-induced light scattering in a thin xenon layer between graphite slabs - MD study.  

PubMed

The collision-induced light scattering many-body correlation functions and their spectra in thin xenon layer located between two parallel graphite slabs have been investigated by molecular dynamics computer simulations. The results have been obtained at three different distances (densities) between graphite slabs. Our simulations show the increased intensity of the interaction-induced light scattering spectra at low frequencies for xenon atoms in confined space, in comparison to the bulk xenon sample. Moreover, we show substantial dependence of the interaction-induced light scattering correlation functions of xenon on the distances between graphite slabs. The dynamics of xenon atoms in a confined space was also investigated by calculating the mean square displacement functions and related diffusion coefficients. The structural property of confined xenon layer was studied by calculating the density profile, perpendicular to the graphite slabs. Building of a fluid phase of xenon in the innermost part of the slot was observed. The nonlinear dependence of xenon diffusion coefficient on the separation distance between graphite slabs has been found. PMID:24755364

Dawid, A; Górny, K; Wojcieszyk, D; Dendzik, Z; Gburski, Z

2014-08-14

334

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

335

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...

336

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

337

Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experiment  

E-print Network

XENON is a direct detection dark matter project, consisting of a time projection chamber (TPC) that uses xenon in double phase as a sensitive detection medium. XENON100, located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, is one of the most sensitive experiments of its field. During the operation of XENON100, the design and construction of the next generation detector (of ton-scale mass) of the XENON project, XENON1T, is taking place. XENON1T is being installed at LNGS as well. It has the goal to reduce the background by two orders of magnitude compared to XENON100, aiming at a sensitivity of $2 \\cdot 10^{-47} \\mathrm{cm}^{\\mathrm{2}}$ for a WIMP mass of 50 GeV/c$^{2}$. With this goal, an active system that is able to tag muons and their induced backgrounds is crucial. This active system will consist of a water Cherenkov detector realized with a water volume $\\sim$10 m high and $\\sim$10 m in diameter, equipped with photomultipliers of 8 inches diameter and a reflective foil. In this paper we p...

Aprile, E; Alfonsi, M; Arisaka, K; Arneodo, F; Auger, M; Balan, C; Barrow, P; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Bokeloh, K; Breskin, A; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Cardoso, J M R; Colijn, A P; Contreras, H; Cussonneau, J P; Decowski, M P; Duchovni, E; Fattori, S; Ferella, A D; Fulgione, W; Garbini, M; Geis, C; Goetzke, L W; Grignon, C; Gross, E; Hampel, W; Itay, R; Kaether, F; Kessler, G; Kish, A; Landsman, H; Lang, R F; Calloch, M Le; Lellouch, D; Levinson, L; Levy, C; Lindemann, S; Lindner, M; Lopes, J A M; Lung, K; Lyashenko, A; MacMullin, S; Undagoitia, T Marrodán; Masbou, J; Massoli, F V; Paras, D Mayani; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Miguez, B; Molinario, A; Morana, G; Murra, M; Naganoma, J; Oberlack, U; Orrigo, S E A; Pantic, E; Persiani, R; Piastra, F; Pienaar, J; Plante, G; Priel, N; Reichard, S; Reuter, C; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schindler, S; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Tiseni, A; Trinchero, G; Vitells, O; Wang, H; Weber, M; Weinheimer., C

2014-01-01

338

Electronic spectroscopy of oxygen atoms trapped in solid xenon W. G. Lawrence and V. A. Apkarian  

E-print Network

Electronic spectroscopy of oxygen atoms trapped in solid xenon W. G. Lawrence and V. A. Apkarian28 August 1992) The electronic spectroscopyof oxygen atoms trapped in solid xenon are reported and -covalent many-body surfacesare discussed. I. INTRODUCTION The electronic spectroscopyof atomic impurities

Apkarian, V. Ara

339

The search for particle dark matter with the XENON imaging time projection chambers  

NASA Astrophysics Data System (ADS)

The worldwide race to direct dark matter detection has been accelerated by the evolution of Liquid Xenon Time Projection Chambers (LXeTPCs). The XENON program has demonstrated the effective scaling of LXeTPCs with phased detectors of increasing sensitivity.

Aprile, E.

2013-01-01

340

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

341

CARBON DIOXIDE FIXATION.  

SciTech Connect

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} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

FUJITA,E.

2000-01-12

342

Modeling Carbon Dioxide Levels  

NSDL National Science Digital Library

In this activity students will explore levels of Carbon Dioxide ( C02) in the atmosphere over time. There is concern that levels of C02 are rising; and finding a good mathematical model for CO2 levels is an important part of determining if this is attributable to human technology. Students draw a scatter plot, choose two points to create a linear model for the data, then use the model to make predictions.

2009-01-01

343

Observation and applications of single-electron charge signals in the XENON100 experiment  

NASA Astrophysics Data System (ADS)

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter weakly interacting massive particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

Aprile, E.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Balan, C.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, A.; Brown, E.; Bruenner, S.; 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.; Itay, R.; Kaether, F.; Kessler, G.; 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.; Marrodán Undagoitia, T.; Massoli, F. V.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Molinario, A.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Piastra, F.; Plante, G.; Priel, N.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

2014-03-01

344

Observation and applications of single-electron charge signals in the XENON100 experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

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

2013-11-05

345

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

346

Scalability, scintillation readout and charge drift in a kilogram scale solid xenon particle detector  

E-print Network

We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employ a liquid nitrogen cooled cryostat combined with a xenon purification and chiller system to measure the scintillation light output and electron drift speed from both the solid and liquid phases of xenon. Scintillation light output from sealed radioactive sources is measured by a set of high quantum efficiency photomultiplier tubes suitable for cryogenic applications. We observed a reduced amount of photons in solid phase compared to that in liquid phase. We used a conventional time projection chamber system to measure the electron drift time in a kilogram of solid xenon and observed faster electron drift speed in the solid phase xenon compared to that in the liquid phase.

Yoo, J; Jaskierny, W F; Markley, D; Pahlka, R B; Balakishiyeva, D; Saab, T; Filipenko, M

2014-01-01

347

Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures.  

PubMed

Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7?GPa and 250?°C, while Ag(+) is reduced to metallic Ag and possibly oxidized to Ag(2+). In contrast to krypton, xenon is retained within the pores of this zeolite after pressure release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres. PMID:25143221

Seoung, Donghoon; Lee, Yongmoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang-Yong; Blom, Douglas A; Evans, William J; Kao, Chi-Chang; Vogt, Thomas; Lee, Yongjae

2014-09-01

348

Observation and applications of single-electron charge signals in the XENON100 experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

Aprile, E; Arisaka, K; Arneodo, F; Balan, C; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Bokeloh, K; Brown, A; Brown, E; Bruenner, S; 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; Itay, R; Kaether, F; Kessler, G; Kish, A; Lamblin, J; Landsman, H; Lang, R F; Calloch, M Le; Levy, C; Lim, K E; Lin, Q; Lindemann, S; Lindner, M; Lopes, J A M; Lung, K; Undagoitia, T Marrodan; Massoli, F V; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Molinario, A; Naganoma, J; Ni, K; Oberlack, U; Orrigo, S E A; Pantic, E; Persiani, R; Piastra, F; Plante, G; Priel, N; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Vitells, O; Wang, H; Weber, M; Weinheimer, C

2014-01-01

349

Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures  

NASA Astrophysics Data System (ADS)

Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7?GPa and 250?°C, while Ag+ is reduced to metallic Ag and possibly oxidized to Ag2+. In contrast to krypton, xenon is retained within the pores of this zeolite after pressure release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.

Seoung, Donghoon; Lee, Yongmoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang-Yong; Blom, Douglas A.; Evans, William J.; Kao, Chi-Chang; Vogt, Thomas; Lee, Yongjae

2014-09-01

350

Xenon Sputter Yield Measurements for Ion Thruster Materials  

NASA Technical Reports Server (NTRS)

In this paper, we describe a technique that was used to measure total and differential sputter yields of materials important to high specific impulse ion thrusters. The heart of the technique is 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. Differential sputtering yields were generally measured over a full 180 deg arc in a plane that included the beam centerline and the normal vector to the target surface. Sputter yield results are presented for a xenon ion energy range from 0.5 to 10 keV and an angle of incidence range from 0 deg to 70 deg from the target surface normal direction for targets consisting of molybdenum, titanium, solid (Poco) graphite, and flexible graphite (grafoil). Total sputter yields are calculated using a simple integration procedure and comparisons are made to sputter yields obtained from the literature. In general, the agreement between the available data is good. As expected for heavy xenon ions, the differential and total sputter yields are found to be strong functions of angle of incidence. Significant under- and over-cosine behavior is observed at low- and high-ion energies, respectively. In addition, strong differences in differential yield behavior are observed between low-Z targets (C and Ti) and high-Z targets (Mo). Curve fits to the differential sputter yield data are provided. They should prove useful to analysts interested in predicting the erosion profiles of ion thruster components and determining where the erosion products re-deposit.

Williams, John D.; Gardner, Michael M.; Johnson, Mark L.; Wilbur, Paul J.

2003-01-01

351

Bulk viscosity of stirred xenon near the critical point  

NASA Astrophysics Data System (ADS)

We deduce the thermophysical properties of near-critical xenon from measurements of the frequencies and half-widths of the acoustic resonances of xenon maintained at its critical density in centimeter-sized cavities. In the reduced temperature range 1×10-3<(T-Tc)/Tc<7×10-6 , we measured the resonance frequency and quality factor (Q) for each of six modes spanning a factor of 27 in frequency. As Tc was approached, the frequencies decreased by a factor of 2.2 and the Q ’s decreased by as much as a factor of 140. Remarkably, these results are predicted (within ±2% of the frequency and within a factor of 1.4 of Q ) by a model for the resonator and a model for the frequency-dependent bulk viscosity ?(?) that uses no empirically determined parameters. The resonator model is based on a theory of acoustics in near-critical fluids developed by Gillis, Shinder, and Moldover [Phys. Rev. E 70, 021201 (2004)]. In addition to describing the present low-frequency data (from 120Hzto7.5kHz ), the model for ?(?) is consistent with ultrasonic (0.4-7MHz) velocity and attenuation data from the literature. However, the model predicts a peak in the temperature dependence of the dissipation in the boundary layer that we did not detect. This suggests that the model overestimates the effect of the bulk viscosity on the thermal boundary layer. In this work, the acoustic cavities were heated from below to stir the xenon, thereby reducing the density stratification resulting from Earth’s gravity. The stirring reduced the apparent equilibration time from several hours to a few minutes, and it reduced the effective temperature resolution from 60mK to approximately 2mK , which corresponds to (T-Tc)/Tc?7×10-6 .

Gillis, K. A.; Shinder, I. I.; Moldover, M. R.

2005-11-01

352

The polarization sensitivity of the liquid xenon imaging telescope  

NASA Technical Reports Server (NTRS)

The properties and the expected performance of a liquid xenon (LXe) gamma-ray imaging telescope, optimized for the MeV energy region, are presented. The unique potential of this telescope as a Compton polarimeter is particularly emphasized. Based on Monte Carlo simulations, we show that the modulation factor is as high as 40% at 1 MeV with a detection efficiency close to 20%. These figures of merit, combined with the excellent background suppression capability of the three-dimensional position sensitive LXe detector, yield sensitivity at the 3 sigma level to polarization fractions as small as a few percent for strong sources, even in a balloon flight.

Aprile, E.; Bolotnikov, A.; Chen, D.; Mukherjee, R.; Xu, F.

1994-01-01

353

Shear Thinning Near the Critical Point of Xenon  

NASA Technical Reports Server (NTRS)

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(exp -3) < gamma-dot tau < 700, where gamma-dot tau is the shear rate scaled by the relaxation time tau of critical fluctuations. The measurements had a temperature resolution of 0.01 mK and were conducted in microgravity aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity. The viscometer measured the drag on a delicate nickel screen as it oscillated in the xenon at amplitudes 3 mu,m < chi (sub 0) >430 mu, and frequencies 1 Hz < omega/2 pi < 5 Hz. To separate shear thinning from other nonlinearities, we computed the ratio of the viscous force on the screen at gamma-dot tau to the force at gamma-dot tau approximates 0: C(sub gamma) is identical with F(chi(sub 0), omega tau, gamma-dot tau )/F)(chi(sub 0, omega tau, 0). At low frequencies, (omega tau)(exp 2) < gamma-dot tau, C(sub gamma) depends only on gamma-dot tau, as predicted by dynamic critical scaling. At high frequencies, (omega tau)(exp 2) > gamma-dot tau, C(sub gamma) depends also on both x(sub 0) and omega. The data were compared with numerical calculations based on the Carreau-Yasuda relation for complex fluids: eta(gamma-dot)/eta(0)=[1+A(sub gamma)|gamma-dot tau|](exp - chi(sub eta)/3+chi(sub eta)), where chi(sub eta) =0.069 is the critical exponent for viscosity and mode-coupling theory predicts A(sub gamma) =0.121. For xenon we find A(sub gamma) =0.137 +/- 0.029, in agreement with the mode coupling value. Remarkably, the xenon data close to the critical temperature T(sub c) were independent of the cooling rate (both above and below T(sub c) and these data were symmetric about T(sub c) 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 T(sub c).

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

2008-01-01

354

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

355

Dielectronic Recombination Cross-Sections of Fluorinelike Xenon  

E-print Network

PHYSICAL REVIEW A VOLUME 47, NUMBER 3 MARCH 1993 Dielectronic recombination cross sections of Snorinelike xenon D. R. DeWitt, D. Schneider, M. H. Chen, and M. B. Schneider Laturence Li uermore National Laboratory, Uniuersity of California.... E. Marrs, M. A. Levine, C. L. Bennett, M. H. Chen, J. R. Henderson, M. B. Schneider, and J. H. Scofield, Phys. Rev. Lett. 62, 2104 (1989). [4] R. Ali, C. P. Bhalla, C. L. Cocke, M. Schulz, and M. Stockli, Phys. Rev. A 44, 223 (1991);R. Ali, C. P...

Dewitt, D. R.; Schneider, D.; Chen, M. H.; Schneider, M. B.; Church, David A.; Weinberg, G.; Sakurai, M.

1993-01-01

356

Mission Advantages of NEXT: Nasa's Evolutionary Xenon Thruster  

NASA Technical Reports Server (NTRS)

With the demonstration of the NSTAR propulsion system on the Deep Space One mission, the range of the Discovery class of NASA missions can now be expanded. NSTAR lacks, however, sufficient performance for many of the more challenging Office of Space Science (OSS) missions. Recent studies have shown that NASA's Evolutionary Xenon Thruster (NEXT) ion propulsion system is the best choice for many exciting potential OSS missions including outer planet exploration and inner solar system sample returns. The NEXT system provides the higher power, higher specific impulse, and higher throughput required by these science missions.

Oleson, Steven; Gefert, Leon; Benson, Scott; Patterson, Michael; Noca, Muriel; Sims, Jon

2002-01-01

357

The adsorption of argon, krypton and xenon on activated charcoal  

SciTech Connect

Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

1996-08-01

358

Krypton and xenon in the atmosphere of Venus  

NASA Astrophysics Data System (ADS)

The paper reports a determination by the Pioneer Venus large probe neutral mass spectrometer of upper limits to the concentration of krypton and xenon along with most of their isotopes in the atmosphere of Venus. The upper limit to the krypton mixing ratio is estimated at 47 ppb, with a very conservative estimate at 69 ppb. The probable upper limit to the sum of the mixing ratios of the isotopes Xe-128, Xe-129, Xe-130, Xe-131, and Xe-132 is 40 ppb by volume, with a very conservative upper limit three times this large.

Donahue, T. M.; Hoffman, J. H.; Hodges, R. R.

1981-05-01

359

A 5-kW xenon ion thruster lifetest  

NASA Technical Reports Server (NTRS)

The results of the first life test of a high power ring-cusp ion thruster are presented. A 30-cm laboratory model thruster was operated steady-state at a nominal beam power of 5 kW on xenon propellant for approximately 900 hours. This test was conducted to identify life-timing erosion modifications, and to demonstrate operation using simplified power processing. The results from this test are described including the conclusions derived from extensive post-test analyses of the thruster. Modifications to the thruster and ground support equipment, which were incorporated to solve problems identified by the lifetest, are also described.

Patterson, Michael J.; Verhey, Timothy R.

1990-01-01

360

Frequency-Dependent Viscosity of Xenon Near the Critical Point  

NASA Technical Reports Server (NTRS)

We used a novel, overdamped oscillator aboard the Space Shuttle to measure the viscosity eta of xenon near its critical density rho(sub c), and temperature T(sub c). In microgravity, useful data were obtained within 0.1 mK of T(sub c), corresponding to a reduced temperature t = (T -T(sub c))/T(sub c) = 3 x 10(exp -7). The data extend two decades closer to T(sub c) than the best ground measurements, and they directly reveal the expected power-law behavior eta proportional to t(sup -(nu)z(sub eta)). Here nu is the correlation length exponent, and our result for the small viscosity exponent is z(sub eta) = 0.0690 +/- 0.0006. (All uncertainties are one standard uncertainty.) Our value for z(sub eta) 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. The measurements spanned the frequency range 2 Hz less than or equal to f less than or equal to 12 Hz and revealed viscoelasticity when t less than or equal to 10(exp -1), further from T(sub c) than predicted. The viscoelasticity scales as Af(tau), where tau 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 T(sub c), 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 rho(sub c), by judicious choices of the temperature vs. time program. Deliberately bad choices led to large density inhomogeneities. At t greater than 10(exp -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.

1999-01-01

361

Ultrafast measurements of chlorine dioxide photochemistry  

SciTech Connect

Time-resolved mass spectrometry and time-resolved photoelectron spectroscopy are used to study the ultrafast photodissociation dynamics of chlorine dioxide, an important constituent in stratospheric ozone depletion. Chapter 1 introduces these pump/probe techniques, in which a femtosecond pump pulse excites a molecule to a dissociative state. At a later time, a second femtosecond probe pulse ionizes the molecule. The resulting mass and photoelectron spectra are acquired as a function of the delay between the pump and probe pulses, which follows the evolution of the molecule on the excited state. A comparison to other techniques used to study reaction dynamics is discussed. Chapter 2 includes a detailed description of the design and construction of the experimental apparatus, which consists of a femtosecond laser system, a molecular beam time-of-flight spectrometer, and a data acquisition system. The time-of-flight spectrometer is specifically designed to have a short flight distance to maximize the photoelectron collection efficiency without degrading the resolution, which is limited by the bandwidth of the femtosecond laser system. Typical performance of the apparatus is demonstrated in a study of the time-resolved photoelectron spectroscopy of nitric oxide. The results of the time-resolved mass spectrometry experiments of chlorine dioxide are presented in Chapter 3. Upon excitation to the A {sup 2}A{sub 2} state near 3.2 eV, the molecule dissociates through an indirect two-step mechanism. The direct dissociation channel has been predicted to be open, but is not observed. A quantum beat is observed in the OClO{sup +} species, which is described as a vibrational coherence of the optically prepared A {sup 2}A{sub 2} state. Chapter 4 presents the results of the time-resolved photoelectron experiments of chlorine dioxide. At short delay time, the quantum beat of the OClO{sup +} species is observed in the X {sup 1}A{sub 1} state of the ion. At infinite delay, the signal is dominated by the ClO{sup +} ion, observed in a variety of electronic states. The photoelectron data is shown to support the indirect two-step dissociation mechanism derived from the mass results. Conclusions of the mass and photoelectron results are discussed in context of the stratospheric ozone depletion problem.

Ludowise, P.D.

1997-08-01

362

Water and Carbon Dioxide Adsorption at Olivine Surfaces  

SciTech Connect

Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

2013-11-14

363

Scintillation response of liquid xenon to low energy nuclear recoils  

NASA Astrophysics Data System (ADS)

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from C57o. The scintillation yield of 56.5 keV recoils was also measured as a function of applied electric field, and compared to that of gamma rays and alpha particles. The Xe recoils were produced by elastic scattering of 2.4 MeV neutrons in liquid xenon at a variety of scattering angles. The relative scintillation efficiency is 0.130±0.024 and 0.227±0.016 for the lowest and highest energy recoils, respectively. This is about 15% less than the value predicted by Lindhard, based on nuclear quenching. Our results are in good agreement with more recent theoretical predictions that consider the additional reduction of scintillation yield due to biexcitonic collisions in LXe.

Aprile, E.; Giboni, K. L.; Majewski, P.; Ni, K.; Yamashita, M.; Hasty, R.; Manzur, A.; McKinsey, D. N.

2005-10-01

364

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

365

Scintillation response of liquid xenon to low energy nuclear recoils  

SciTech Connect

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from {sup 57}Co. The scintillation yield of 56.5 keV recoils was also measured as a function of applied electric field, and compared to that of gamma rays and alpha particles. The Xe recoils were produced by elastic scattering of 2.4 MeV neutrons in liquid xenon at a variety of scattering angles. The relative scintillation efficiency is 0.130{+-}0.024 and 0.227{+-}0.016 for the lowest and highest energy recoils, respectively. This is about 15% less than the value predicted by Lindhard, based on nuclear quenching. Our results are in good agreement with more recent theoretical predictions that consider the additional reduction of scintillation yield due to biexcitonic collisions in LXe.

Aprile, E.; Giboni, K.L.; Majewski, P.; Ni, K.; Yamashita, M.; Hasty, R.; Manzur, A.; McKinsey, D.N. [Physics Department and Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States); Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520 (United States)

2005-10-01

366

First Axion Results from the XENON100 Experiment  

E-print Network

We present the first results of searches for axions and axion-like-particles with the XENON100 experiment. The axion-electron coupling constant, $g_{Ae}$, has been tested by exploiting the axio-electric effect in liquid xenon. A profile likelihood analysis of 224.6 live days $\\times$ 34 kg exposure has shown no evidence for a signal. By rejecting $g_{Ae}$, larger than $7.7 \\times 10^{-12}$ (90% CL) in the solar axion search, we set the best limit to date on this coupling. In the frame of the DFSZ and KSVZ models, we exclude QCD axions heavier than 0.3 eV/c$^2$ and 80 eV/c$^2$, respectively. For axion-like-particles, under the assumption that they constitute the whole abundance of dark matter in our galaxy, we constrain $g_{Ae}$, to be lower than $1 \\times 10^{-12}$ (90% CL) for masses between 5 and 10 keV/c$^2$.

Aprile, E; Alfonsi, M; Arisaka, K; Arneodo, F; Auger, M; Balan, C; Barrow, P; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Bokeloh, K; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Cardoso, J M R; Colijn, A P; Contreras, H; Cussonneau, J P; Decowski, M P; Duchovni, E; Fattori, S; Ferella, A D; Fulgione, W; Gao, F; Garbini, M; Geis, C; Goetzke, L W; Grignon, C; Gross, E; Hampel, W; Itay, R; Kaether, F; Kessler, G; Kish, A; Landsman, H; Lang, R F; Calloch, M Le; Lellouch, D; Levy, C; Lindemann, S; Lindner, M; Lopes, J A M; Lung, K; Lyashenko, A; Macmullin, S; Undagoitia, T Marrodan; Masbou, J; Massoli, F V; Paras, D Mayani; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Miguez, B; Molinario, A; Murra, M; Naganoma, J; Oberlack, U; Orrigo, S E A; Pantic, E; Persiani, R; Piastra, F; Pienaar, J; Plante, G; Priel, N; Reichard, S; Reuter, C; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schindler, S; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Tiseni, A; Trinchero, G; Vitells, O; Wang, H; Weber, M; Weinheimer, C

2014-01-01

367

Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) enables high-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI reporters of key biological processes tied to gene expression have been limited by the inherently low molecular sensitivity of conventional 1H MRI. This limitation could be overcome through the use of hyperpolarized nuclei, such as in the noble gas xenon, but previous reporters acting on such nuclei have been synthetic. Here, we introduce the first genetically encoded reporters for hyperpolarized 129Xe MRI. These expressible reporters are based on gas vesicles (GVs), gas-binding protein nanostructures expressed by certain buoyant microorganisms. We show that GVs are capable of chemical exchange saturation transfer interactions with xenon, which enables chemically amplified GV detection at picomolar concentrations (a 100- to 10,000-fold improvement over comparable constructs for 1H MRI). We demonstrate the use of GVs as heterologously expressed indicators of gene expression and chemically targeted exogenous labels in MRI experiments performed on living cells.

Shapiro, Mikhail G.; Ramirez, R. Matthew; Sperling, Lindsay J.; Sun, George; Sun, Jinny; Pines, Alexander; Schaffer, David V.; Bajaj, Vikram S.

2014-07-01

368

First Axion Results from the XENON100 Experiment  

E-print Network

We present the first results of searches for axions and axion-like-particles with the XENON100 experiment. The axion-electron coupling constant, $g_{Ae}$, has been tested by exploiting the axio-electric effect in liquid xenon. A profile likelihood analysis of 224.6 live days $\\times$ 34 kg exposure has shown no evidence for a signal. By rejecting $g_{Ae}$, larger than $7.7 \\times 10^{-12}$ (90% CL) in the solar axion search, we set the best limit to date on this coupling. In the frame of the DFSZ and KSVZ models, we exclude QCD axions heavier than 0.3 eV/c$^2$ and 80 eV/c$^2$, respectively. For axion-like-particles, under the assumption that they constitute the whole abundance of dark matter in our galaxy, we constrain $g_{Ae}$, to be lower than $1 \\times 10^{-12}$ (90% CL) for masses between 5 and 10 keV/c$^2$.

The XENON100 Collaboration; E. Aprile; F. Agostini; M. Alfonsi; K. Arisaka; F. Arneodo; M. Auger; C. Balan; P. Barrow; L. Baudis; B. Bauermeister; A. Behrens; P. Beltrame; K. Bokeloh; A. Brown; E. Brown; S. Bruenner; G. Bruno; R. Budnik; J. M. R. Cardoso; A. P. Colijn; H. Contreras; J. P. Cussonneau; M. P. Decowski; E. Duchovni; S. Fattori; A. D. Ferella; W. Fulgione; F. Gao; M. Garbini; C. Geis; L. W. Goetzke; C. Grignon; E. Gross; W. Hampel; R. Itay; F. Kaether; G. Kessler; A. Kish; H. Landsman; R. F. Lang; M. Le Calloch; D. Lellouch; C. Levy; S. Lindemann; M. Lindner; J. A. M. Lopes; K. Lung; A. Lyashenko; S. Macmullin; T. Marrodan Undagoitia; J. Masbou; F. V. Massoli; D. Mayani Paras; A. J. Melgarejo Fernandez; Y. Meng; M. Messina; B. Miguez; A. Molinario; M. Murra; J. Naganoma; U. Oberlack; S. E. A. Orrigo; E. Pantic; R. Persiani; F. Piastra; J. Pienaar; G. Plante; N. Priel; S. Reichard; C. Reuter; A. Rizzo; S. Rosendahl; J. M. F. dos Santos; G. Sartorelli; S. Schindler; J. Schreiner; M. Schumann; L. Scotto Lavina; M. Selvi; P. Shagin; H. Simgen; A. Teymourian; D. Thers; A. Tiseni; G. Trinchero; O. Vitells; H. Wang; M. Weber; C. Weinheimer

2014-04-05

369

Performance characteristics of ring-cusp thrusters with xenon propellant  

NASA Technical Reports Server (NTRS)

The performance characteristics and operating envelope of several 30-cm ring-cusp ion thrusters with xenon propellant were investigated. Results indicate a strong performance dependence on the discharge chamber boundary magnetic fields and resultant distribution of electron currents. Significant improvements in discharge performance over J-series divergent-field thrusters were achieved for large throttling ranges, which translate into reduced cathode emission currents and reduced power dissipation which should be of significant benefit for operation at thruster power levels in excess of 10 kW. Mass spectrometry of the ion beam was documented for both the ring-cusp and J-series thrusters with xenon propellant for determination of overall thruster efficiency, and lifetime. Based on the lower centerline values of doubly charged ions in the ion beam and the lower operating discharge voltage, the screen grid erosion rate of the ring-cusp thruster is expected to be lower than the divergent-field J-series thruster by a factor of 2.

Patterson, M. J.

1986-01-01

370

Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water$-$Xe system  

E-print Network

Motivated by recent experiments showing the promise of noble gases as cryoprotectants, we perform molecular dynamics modeling of phase transitions in water with xenon under cooling. We study the structure and dynamics of xenon water solution as a function of temperature. Homogeneous nucleation of clathrate hydrate phase is observed and characterized. As the temperature is further reduced we observe hints of dissociation of clathrate due to stronger hydrophobic hydration, pointing towards a possible instability of clathrate at cryogenic temperatures and conversion to an amorphous phase comprised of "xenon + hydration shell" Xe$\\cdot$(H$_{2}$O)$_{21.5}$ clusters. Simulations of ice$-$xenon solution interface in equilibrium and during ice growth reveal the effects of xenon on the ice$-$liquid interface, where adsorbed xenon causes roughening of ice surface but does not preferentially form clathrate. These results provide evidence against the ice-blocker mechanism of xenon cryoprotection.

Vasilii I. Artyukhov; Alexander Yu. Pulver; Alex Peregudov; Igor Artyuhov

2014-07-11

371

Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water$-$Xe system  

E-print Network

Motivated by recent experiments showing the promise of noble gases as cryoprotectants, we perform molecular dynamics modeling of phase transitions in water with xenon under cooling. We study the structure and dynamics of xenon water solution as a function of temperature. Homogeneous nucleation of clathrate hydrate phase is observed and characterized. As the temperature is further reduced we observe hints of dissociation of clathrate due to stronger hydrophobic hydration, pointing towards a possible instability of clathrate at cryogenic temperatures and conversion to an amorphous phase comprised of "xenon + hydration shell" Xe$\\cdot$(H$_{2}$O)$_{21.5}$ clusters. Simulations of ice$-$xenon solution interface in equilibrium and during ice growth reveal the effects of xenon on the ice$-$liquid interface, where adsorbed xenon causes roughening of ice surface but does not preferentially form clathrate. These results provide evidence against the ice-blocker mechanism of xenon cryoprotection.

Artyukhov, Vasilii I; Peregudov, Alex; Artyuhov, Igor

2014-01-01

372

Process for sequestering carbon dioxide and sulfur dioxide  

DOEpatents

A process for sequestering carbon dioxide, which includes reacting a silicate based material with an acid to form a suspension, and combining the suspension with carbon dioxide to create active carbonation of the silicate-based material, and thereafter producing a metal salt, silica and regenerating the acid in the liquid phase of the suspension.

Maroto-Valer, M. Mercedes (State College, PA); Zhang, Yinzhi (State College, PA); Kuchta, Matthew E. (State College, PA); Andresen, John M. (State College, PA); Fauth, Dan J. (Pittsburgh, PA)

2009-10-20

373

21 CFR 73.3126 - Titanium dioxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Titanium dioxide. 73.3126 Section 73... Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No....

2014-04-01

374

21 CFR 73.1575 - Titanium dioxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Titanium dioxide. 73.1575 Section...CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in...

2013-04-01

375

21 CFR 73.3126 - Titanium dioxide.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Titanium dioxide. 73.3126 Section 73... Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No....

2011-04-01

376

21 CFR 73.2575 - Titanium dioxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Titanium dioxide. 73.2575 Section 73...CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in...

2013-04-01

377

21 CFR 73.575 - Titanium dioxide.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575...CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared...

2010-04-01

378

21 CFR 73.1575 - Titanium dioxide.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Titanium dioxide. 73.1575 Section...CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in...

2010-04-01

379

21 CFR 73.575 - Titanium dioxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Titanium dioxide. 73.575 Section 73.575...CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared...

2012-04-01

380

21 CFR 73.2575 - Titanium dioxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Titanium dioxide. 73.2575 Section 73...CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in...

2012-04-01

381

21 CFR 73.575 - Titanium dioxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Titanium dioxide. 73.575 Section 73.575...CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared...

2014-04-01

382

21 CFR 73.2575 - Titanium dioxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Titanium dioxide. 73.2575 Section 73...CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in...

2014-04-01

383

21 CFR 73.575 - Titanium dioxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Titanium dioxide. 73.575 Section 73.575...CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared...

2013-04-01

384

21 CFR 73.3126 - Titanium dioxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Titanium dioxide. 73.3126 Section 73... Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No....

2013-04-01

385

21 CFR 73.1575 - Titanium dioxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Titanium dioxide. 73.1575 Section...CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in...

2012-04-01

386

21 CFR 73.1575 - Titanium dioxide.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Titanium dioxide. 73.1575 Section...CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in...

2011-04-01

387

21 CFR 73.575 - Titanium dioxide.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Titanium dioxide. 73.575 Section 73.575...CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared...

2011-04-01

388

21 CFR 73.3126 - Titanium dioxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Titanium dioxide. 73.3126 Section 73... Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No....

2012-04-01

389

21 CFR 73.3126 - Titanium dioxide.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73... Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No....

2010-04-01

390

21 CFR 73.1575 - Titanium dioxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Titanium dioxide. 73.1575 Section...CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in...

2014-04-01

391

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 2012-04-01 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...

2012-04-01

392

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 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...

2011-04-01

393

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 2014-04-01 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...

2014-04-01

394

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 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...

2013-04-01

395

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 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...

2010-04-01

396

Carbon Dioxide Reduction Through Urban Forestry  

E-print Network

Carbon Dioxide Reduction Through Urban Forestry: Guidelines for Professional and Volunteer Tree; Simpson, James R. 1999. Carbon dioxide reduction through urban forestry of Agriculture; 237 p. Carbon dioxide reduction through urban forestry--Guidelines for professional and volunteer

Standiford, Richard B.

397

GraXe, graphene and xenon for neutrinoless double beta decay searches  

NASA Astrophysics Data System (ADS)

We propose a new detector concept, GraXe (to be pronounced as grace), to search for neutrinoless double beta decay in 136XE. GraXe combines a popular detection medium in rare-event searches, liquid xenon, with a new, background-free material, graphene. In our baseline design of GraXe, a sphere made of graphene-coated titanium mesh and filled with liquid xenon (LXe) enriched in the 136XE isotope is immersed in a large volume of natural LXe instrumented with photodetectors. Liquid xenon is an excellent scintillator, reasonably transparent to its own light. Graphene is transparent over a large frequency range, and impermeable to the xenon. Event position could be deduced from the light pattern detected in the photosensors. External backgrounds would be shielded by the buffer of natural LXe, leaving the ultra-radiopure internal volume virtually free of background. Industrial graphene can be manufactured at a competitive cost to produce the sphere. Enriching xenon in the isotope 136XE is easy and relatively cheap, and there is already near one ton of enriched xenon available in the world (currently being used by the EXO, KamLAND-Zen and NEXT experiments). All the cryogenic know-how is readily available from the numerous experiments using liquid xenon. An experiment using the GraXe concept appears realistic and affordable in a short time scale, and its physics potential is enormous.

Gómez-Cadenas, J. J.; Guinea, F.; Fogler, M. M.; Katsnelson, M. I.; Martín-Albo, J.; Monrabal, F.; Muñoz Vidal, J.

2012-02-01

398

In-situ laser tagging of barium ions in liquid xenon for the EXO experiment  

NASA Astrophysics Data System (ADS)

The goal of the Enriched Xenon Observatory (EXO) collaboration is to measure the half-life of neutrino-less double beta decay using a ton size liquid 136Xe detector with zero back-ground. Zero background detection can only be achieved if the daughter nucleus, 136Ba, can be tagged. The EXO collaboration is investigating several techniques to tag the 136Ba daughter. The goal of this thesis is to investigate the prospects of directly observing a single 136Ba+ ion in the liquid using a laser aimed at the decay site, hence in-situ laser tagging. Because the energy levels of Ba+ ions are expected to be altered from the vacuum configuration, in-situ laser tagging can only be accomplished if the spectroscopy of the Ba+ ions in liquid xenon is understood. An ultra pure liquid xenon test apparatus with a liquid xenon purity monitor has been built to study the spectroscopy of the Ba+ ions. An unexpected discovery of the nonresonant multiphoton ionization of liquid xenon using pulsed UV lasers was made while characterizing the purity monitor. The discovery was vital to the ability to accurately measure the purity of the liquid xenon. The spectroscopy of Ba+ ions in liquid xenon and the multiphoton ionization studies are the two key topics that are presented in this thesis.

Hall, Kendy

399

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

SciTech Connect

Although observations made with the CoGeNT and CDMS experiments have been interpreted as possible signals of low-mass ( ? 7–10 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 (L{sub eff}), and the suppression of the scintillation signal in liquid xenon at XENON100's electric field (S{sub nr}), 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 ? 3–24 per month.

Hooper, Dan, E-mail: dhooper@fnal.gov [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

2013-09-01

400

GraXe, graphene and xenon for neutrinoless double beta decay searches  

E-print Network

We propose a new detector concept, GraXe (to be pronounced as grace), to search for neutrinoless double beta decay in Xe-136. GraXe combines a popular detection medium in rare-event searches, liquid xenon, with a new, background-free material, graphene. In our baseline design of GraXe, a sphere made of graphene-coated titanium mesh and filled with liquid xenon (LXe) enriched in the Xe-136 isotope is immersed in a large volume of natural LXe instrumented with photodetectors. Liquid xenon is an excellent scintillator, reasonably transparent to its own light. Graphene is transparent over a large frequency range, and impermeable to the xenon. Event position could be deduced from the light pattern detected in the photosensors. External backgrounds would be shielded by the buffer of natural LXe, leaving the ultra-radiopure internal volume virtually free of background. Industrial graphene can be manufactured at a competitive cost to produce the sphere. Enriching xenon in the isotope Xe-136 is easy and relatively cheap, and there is already near one ton of enriched xenon available in the world (currently being used by the EXO, KamLAND-Zen and NEXT experiments). All the cryogenic know-how is readily available from the numerous experiments using liquid xenon. An experiment using the GraXe concept appears realistic and affordable in a short time scale, and its physics potential is enormous.

J. J. Gomez-Cadenas; F. Guinea; M. M. Fogler; M. I. Katsnelson; J. Martin-Albo; F. Monrabal; J. Muñoz-Vidal

2012-02-23

401

Response of liquid xenon to low-energy ionizing radiation and its use in the XENON10 dark matter search  

NASA Astrophysics Data System (ADS)

This dissertation focuses on developments aimed at improving the effectiveness and understanding of liquid xenon particle detectors in their use in the field of dark matter direct detection. Chapter 3 covers the XENON10 experiment, which searches for evidence of direct interactions between Weakly Interacting Massive Particles (WIMPs) and Xe nuclei. The 3-D position sensitive liquid xenon time projection chamber acquired 58.6 live days of WIMP search data from October, 2006 through February, 2007. The results of these data set new limits on both spin-independent and spin-dependent interactions. The spin-independent WIMP-nucleon cross section is constrained to be less than 4.5 x 10-44 cm2 for WIMPs of mass 30 GeV/ c2 and less than 8.8 x 10-44 cm2 for WIMPs of mass 100 GeV/c2 at the 90% confidence level. The spin-dependent WIMP-neutron and WIMP-proton cross sections are constrained to be less than 10-39 cm 2 and 10-36 cm2, respectively. Finally, the mass of the heavy Majorana neutrino, in the context of a dark matter candidate, is excluded for masses in the range 10 GeV/c2 to 2.2TeV/c2. Chapter 4 discusses the study of the relative scintillation efficiency of nuclear recoils in liquid xenon. 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. A new measurement of the relative scintillation efficiency below 10 keV, performed with a liquid xenon scintillation detector and optimized for maximum light collection is discussed. 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. The relative scintillation efficiency for nuclear recoils of 5 keV is found to be 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 8.8 x 10-44 cm2 to 9.9 x 10-44 cm2 for WIMPs of mass 100 GeV/c2, and from 4.5 x 10-44 cm2 to 5.6 x 10-44 cm2 for WIMPs of mass 30 GeV/ c2. In Chapter 6, I highlight the fact that a difficult task with many particle detectors focusing on interactions below ˜100 keV is to perform a calibration in the appropriate energy range that adequately probes all regions of the detector. Because detector response can vary greatly in various locations within the device, a spatially uniform calibration is important. A new method for calibration of liquid xenon (LXe) detectors is presented, using the short-lived 83mKr. This source has transitions at 9.4 and 32.1 keV, and as a noble gas like Xe, it disperses uniformly in all regions of the detector. Even for low source activities, the existence of the two transitions provides a method of identifying the decays that is free of background. At decreasing energies, the LXe light yield increases, while the amount of electric field quenching is diminished. Additionally, if any long-lived radioactive backgrounds are introduced by this method, it is shown that they will present less than 67x10 -6 events kg-1 day-1 keV-1 of background in the next generation of LXe dark matter direct detection searches. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Manalaysay, Aaron Gosta

402

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

403

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

404

Reaction products of chlorine dioxide.  

PubMed Central

Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxide treatment of organic materials are oxidized species, some of which also contain chlorine. The relative amounts of species types may depend on the amount of chlorine dioxide residual maintained and the concentration and nature of the organic material present in the source water. The trend toward lower concentrations of chlorinated by-products with increasing ClO2 concentration, which was observed with phenols, has not been observed with natural humic materials as measured by the organic halogen parameter. Organic halogen concentrations have been shown to increase with increasing chlorine dioxide dose, but are much lower than those observed when chlorine is applied. Aldehydes have been detected as apparent by-products of chlorine dioxide oxidation reactions in a surface water that is a drinking water source. Some other nonchlorinated products of chlorine dioxide treatment may be quinones and epoxides. The extent of formation of these moieties within the macromolecular humic structure is also still unknown. PMID:7151750

Stevens, A A

1982-01-01

405

XENON10/100 dark matter constraints: examining the Leff dependence  

E-print Network

The determination of dark matter constraints from liquid xenon direct detection experiments depends upon the amount of scintillation light produced by nuclear recoils in the detector, a quantity that is characterized by the scintillation efficiency factor Leff. We examine how uncertainties in the measurements of Leff and the extrapolated behavior of Leff at low recoil energies (where measurements do not exist) affect the constraints from experiments such as XENON10 and XENON100, particularly in the light WIMP regions of interest for the DAMA and CoGeNT experimental results.

Christopher Savage

2010-12-17

406

Scintillation efficiency for low energy nuclear recoils in liquid xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

We perform a theoretical study of the scintillation efficiency of the low energy region crucial for liquid xenon dark matter detectors. We develop a computer program to simulate the cascading process of the recoiling xenon nucleus in liquid xenon and calculate the nuclear quenching effect due to atomic collisions. We use the electronic stopping power extrapolated from experimental data to the low energy region, and take into account the effects of electron escape from electron-ion pair recombination using the generalized Thomas-Imel model fitted to scintillation data. Our result agrees well with the experiments from neutron scattering and vanishes rapidly as the recoil energy drops below 3 keV.

Mu, Wei; Xiong, Xiaonu; Ji, Xiangdong

2015-02-01

407

Performance of 10-kW class xenon ion thrusters  

NASA Technical Reports Server (NTRS)

Presented are performance data for laboratory and engineering model 30 cm-diameter ion thrusters operated with xenon propellant over a range of input power levels from approximately 2 to 20 kW. Also presented are preliminary performance results obtained from laboratory model 50 cm-diameter cusp- and divergent-field ion thrusters operating with both 30 cm- amd 50 cm-diameter ion optics up to a 20 kW input power. These data include values of discharge chamber propellant and power efficiencies, as well as values of specific impulse, thruster efficiency, thrust and power. The operation of the 30 cm- and 50 cm-diameter ion optics are also discussed.

Patterson, Michael J.; Rawlin, Vincent K.

1988-01-01

408

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils  

E-print Network

Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.

Aprile, E; Majewski, P; Yamashita, M; Hasty, R; Manzur, A; McKinsey, D N

2005-01-01

409

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

410

Dual-phase liquid xenon detectors for dark matter searches  

NASA Astrophysics Data System (ADS)

Dual-phase time projection chambers (TPCs) filled with the liquid noble gas xenon (LXe) are currently the most sensitive detectors searching for interactions of WIMP dark matter in a laboratory-based experiment. This is achieved by combining a large, monolithic dark matter target of a very low background with the capability to localize the interaction vertex in three dimensions, allowing for target fiducialization and multiple-scatter rejection. The background in dual-phase LXe TPCs is further reduced by the simultaneous measurement of the scintillation and ionization signal from a particle interaction, which is used to distinguish signal from background signatures. This article reviews the principle of dual-phase LXe TPCs, and provides an overview about running as well as future experimental efforts.

Schumann, Marc

2014-08-01

411

A linear RFQ ion trap for the Enriched Xenon Observatory  

NASA Astrophysics Data System (ADS)

The design, construction, and performance of a linear radio-frequency ion trap (RFQ) intended for use in the Enriched Xenon Observatory (EXO) are described. EXO aims to detect the neutrinoless double-beta decay of 136Xe to 136Ba. To suppress possible backgrounds EXO will complement the measurement of decay energy and, to some extent, topology of candidate events in a Xe filled detector with the identification of the daughter nucleus ( 136Ba). The ion trap described here is capable of accepting, cooling, and confining individual Ba ions extracted from the site of the candidate double-beta decay event. A single trapped ion can then be identified, with a large signal-to-noise ratio, via laser spectroscopy.

Flatt, B.; Green, M.; Wodin, J.; DeVoe, R.; Fierlinger, P.; Gratta, G.; LePort, F.; Montero Díez, M.; Neilson, R.; O'Sullivan, K.; Pocar, A.; Waldman, S.; Baussan, E.; Breidenbach, M.; Conley, R.; Fairbank, W.; Farine, J.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Hauger, M.; Hodgson, J.; Juget, F.; Leonard, D. S.; Mackay, D.; Martin, Y.; Mong, B.; Odian, A.; Ounalli, L.; Piepke, A.; Prescott, C. Y.; Rowson, P. C.; Skarpaas, K.; Schenker, D.; Sinclair, D.; Strickland, V.; Virtue, C.; Vuilleuimier, J.-L.; Vuilleuimier, J.-M.; Wamba, K.; Weber, P.

2007-08-01

412

A New Electrostatically-focused UV HPD for Liquid Xenon  

SciTech Connect

Appropriate photodetectors are a major challenge for liquid xenon technology as proposed by the next generation of double beta decay, solar neutrino, and dark matter searches. The primary photon signal is tiny and in the hard ultraviolet, the installation is cryogenic, and the sensors themselves must not introduce background. Hybrid photodiodes (HPDs) provide an easy substitute for a conventional PMT with the added advantages of low radioactivity, better area coverage, and single photoelectron counting. A computer-controlled test setup capable of characterizing optical properties of ultraviolet photodetectors was installed. It was used to compare photomultiplier tubes, silicon photomultipliers, avalanche photodiodes, and a novel-design custom HPD developed by the DEP company under this proposal.

Cushman, Priscilla Brooks [University of Minnesota

2013-07-10

413

Deep Space Mission Applications for NEXT: NASA's Evolutionary Xenon Thruster  

NASA Technical Reports Server (NTRS)

NASA's Evolutionary Xenon Thruster (NEXT) is designed to address a need for advanced ion propulsion systems on certain future NASA deep space missions. This paper surveys seven potential missions that have been identified as being able to take advantage of the unique capabilities of NEXT. Two conceptual missions to Titan and Neptune are analyzed, and it is shown that ion thrusters could decrease launch mass and shorten trip time, to Titan compared to chemical propulsion. A potential Mars Sample return mission is described, and compassion made between a chemical mission and a NEXT based mission. Four possible near term applications to New Frontiers and Discovery class missions are described, and comparisons are made to chemical systems or existing NSTAR ion propulsion system performance. The results show that NEXT has potential performance and cost benefits for missions in the Discovery, New Frontiers, and larger mission classes.

Oh, David; Benson, Scott; Witzberger, Kevin; Cupples, Michael

2004-01-01

414

Test of a two-dimensional liquid xenon TPC  

NASA Astrophysics Data System (ADS)

The spatial resolution of a liquid xenon ionization chamber operated in the time projection mode was measured with a multiwire anode structure, using cosmic rays traversing a maximum drift gap of 5.9 cm. From the digitized pulse shape of the ionization signal induced on the anode wires, the timing information was measured for different track orientations in space. In order to estimate the resolution capability of the chamber, tracks entering the chamber at about 50° with respect to the horizontal were selected, as they would most likely induce a signal on all the wires. The accuracy on the measured drift time, limited mostly by electronic noise and electric field shaping, translates into a spatial resolution of 180 ?m rms for the z-coordinate along the drift direction.

Aprile, E.; Chen, D.; Moulson, M.; Mukherjee, R.; Suzuki, M.

1992-05-01

415

Dual-Phase Liquid Xenon Detectors for Dark Matter Searches  

E-print Network

Dual-phase time projection chambers (TPCs) filled with the liquid noble gas xenon (LXe) are currently the most sensitive detectors searching for interactions of WIMP dark matter in a laboratory-based experiment. This is achieved by combining a large, monolithic dark matter target of a very low background with the capability to localize the interaction vertex in three dimensions, allowing for target fiducialization and multiple-scatter rejection. The background in dual-phase LXe TPCs is further reduced by the simultaneous measurement of the scintillation and ionization signal from a particle interaction, which is used to distinguish signal from background signatures. This article reviews the principle of dual-phase LXe TPCs, and provides an overview about running as well as future experimental efforts.

Schumann, Marc

2014-01-01

416

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils  

E-print Network

Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.

E. Aprile; K. L. Giboni; P. Majewski; K. Ni; M. Yamashita; R. Hasty; A. Manzur; D. N. McKinsey

2005-03-29

417

Increasing the Life of a Xenon-Ion Spacecraft Thruster  

NASA Technical Reports Server (NTRS)

A short document summarizes the redesign of a xenon-ion spacecraft thruster to increase its operational lifetime beyond a limit heretofore imposed by nonuniform ion-impact erosion of an accelerator electrode grid. A peak in the ion current density on the centerline of the thruster causes increased erosion in the center of the grid. The ion-current density in the NSTAR thruster that was the subject of this investigation was characterized by peak-to-average ratio of 2:1 and a peak-to-edge ratio of greater than 10:1. The redesign was directed toward distributing the same beam current more evenly over the entire grid andinvolved several modifications of the magnetic- field topography in the thruster to obtain more nearly uniform ionization. The net result of the redesign was to reduce the peak ion current density by nearly a factor of two, thereby halving the peak erosion rate and doubling the life of the thruster.

Goebel, Dan; Polk, James; Sengupta, Anita; Wirz, Richard

2007-01-01

418

Investigation of many-body forces in krypton and xenon  

SciTech Connect

The simplicity of the state dependence at relatively high temperatures ofthe many-body potential contribution to the pressure and energy has been pointed out previously (J. Ram and P. A. Egelstaff, J. Phys. Chem. Liq. 14, 29 (1984); A. Teitsima and P. A. Egelstaff, Phys. Rev. A 21, 367 (1980)). In this paper, we investigate how far these many-body potential terms may be represented by simple models in the case of krypton on the 423-, 273-, 190-, and 150-K isotherms, and xenon on the 170-, 210-, and 270-K isotherms. At the higher temperatures the best agreement is found for the mean-field type of theory, and some consequences are pointed out. On the lower isotherms a state point is found where the many-body energy vanishes, and large departures from mean-field behavior are observed. This is attributed to the influence of short-ranged many-body forces.

Salacuse, J.J.; Egelstaff, P.A.

1988-10-15

419

A liquid xenon detector for PET applications: simulated performance  

NASA Astrophysics Data System (ADS)

We are investigating a liquid xenon (LXe) gamma ray detector-based PET system for small animals. The proposed system consists of 12 modules arranged into a ring. Each detector module is a trapezoidal LXe time projection chamber (TPC) viewed by two arrays of large area avalanche photodiodes (LAAPD). We developed a Geant4-based Monte Carlo code to model the LXe PET system and study its imaging performance. Events depositing energy in multiple locations were reconstructed with a Compton reconstruction algorithm. The simulated data were stored in a list-mode file and reconstructed with the maximum likelihood expectation maximization iterative algorithm (MLEM). Simulation results indicate an absolute sensitivity at the center of the field of view (FOV) of 12.6% and a 3D position resolution <= 0.8 mm (FWHM) throughout the FOV. A simulated image of a micro-Derenzo phantom shows that rods of 0.6 mm diameter are visible.

Miceli, A.; Andreyev, A.; Bryman, D.; Glister, J.; Kurchaninov, L.; Muennich, A.; Retiere, F.; Sossi, V.

2012-03-01

420

Sampling Carbon Dioxide  

NSDL National Science Digital Library

In this lab activity, student teams hypothesize which source has a greater becomes CO² concentration: their breath, auto exhaust, or air in the classroom. They test gas samples from each of these sources, plot data, and hypothesize about the respective role engine exhaust and animal respiration play in contemporary climate change. The lab procedures require Bromthymol Blue indicator solution (BTB), household ammonia, vinegar, and balloons. Links to videos supporting the investigations are provided. This activity is supported by a textbook chapter, "How is Carbon Dioxide Measured?," part of the unit, Climate Change, in Global Systems Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

421

Uranium dioxide electrolysis  

DOEpatents

This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

Willit, James L. (Batavia, IL); Ackerman, John P. (Prescott, AZ); Williamson, Mark A. (Naperville, IL)

2009-12-29

422

Atmospheric Krypton and Xenon Measurements from Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The heavy noble gases krypton and xenon are important tracers of planetary processes from accretion to differentiation and to atmospheric escape. Their abundance and stable isotopic ratios are also indicative of sources as well. The Sample Analysis at Mars (SAM) investigation on the Curiosity rover has measured the Martian atmosphere and reported on the volume mixing ratio of its major constituents (Mahaffy et al., 2013). Here we report the abundance and isotopic ratios of Kr and Xe in the atmosphere of Mars as obtained by semi-static operation of the SAM quadrupole mass spectrometer. Viking provided the first in situ detection of these gases (Owen et al, 1977), suggesting upper limits of 300 ppb for Kr and 80 ppb for Xe, based upon calibration gases with terrestrial isotopic abundances. The abundances of individual isotopes as well as their ratios to one another have been derived from martian meteorite samples by many investigators (e.g., Becker & Pepin, 1984; Bogard & Garrison, 1998). The SAM heavy noble gas data complement the argon isotopic data reported in Mahaffy et al., 2013. Becker, R. H., & Pepin, R. O. (1984). The case for a Martian origin of the shergottites: Nitrogen and noble gases in EETA 79001. Earth and Planetary Science Letters, 69(2), 225-242. Bogard, D. D., & Garrison, D. H. (1998). Relative abundances of argon, krypton, and xenon in the Martian atmosphere as measured in Martian meteorites. Geochimica et cosmochimica acta, 62(10), 1829-1835. Mahaffy, et al., (2013) Abundance and isotopic composition of gases in the martian atmosphere from the Curiosity rover. Science 341, 263-266 Owen, T. et al.,(1977). The composition of the atmosphere at the surface of Mars. Journal of Geophysical research, 82(28), 4635-4639.

Conrad, P. G.; Malespin, C. A.; Franz, H.; Manning, H. L.; Trainer, M. G.; Wong, M. H.; Brunner, A.; Atreya, S. K.; Pepin, R. O.; Jones, J. H.; Owen, T. C.; Mahaffy, P. R.

2013-12-01

423

Large scale xenon purification using cryogenic distillation for dark matter detectors  

NASA Astrophysics Data System (ADS)

A high efficiency cryogenic distillation system for removal of radioactive krypton-85 (85Kr) from commercially available xenon (Xe) has been designed, developed and assessed to meet the requirements of high sensitivity, low background dark matter detection experiments. The concentration of krypton (Kr) in a commercial xenon product can be decreased from 10?9 to 10?12 mol/mol based on the theoretical design and simulation. The experimental measurements showed that the concentration of krypton was decreased to 10?11 mol/mol with 99% xenon collection efficiency at maximum flow rate of 5 kg/h. Over 500 kg of xenon has been purified using this system, which has been used as the detection medium in project Panda X, the first dark matter detector developed in China.

Wang, Z.; Bao, L.; Hao, X. H.; Ju, Y. L.; Pushkin, K.; He, M.

2014-11-01

424

Progress on Acoustic Measurements of the Bulk Viscosity of Near-Critical Xenon (BVX)  

NASA Technical Reports Server (NTRS)

We plan to determine the bulk viscosity of xenon 10 times closer [in reduced temperature tau = (T-Tc)/Tc] to its liquid-vapor critical point than ever before. (Tc is the critical temperature.) To do so, we must measure the dispersion and attenuation of sound at frequencies 1/100 of those used previously. In general, sound attenuation has contributions from the bulk viscosity acting throughout the volume of the xenon as well as contributions from the thermal conductivity and the shear viscosity acting within thin thermoacoustic boundary layers at the interface between the xenon and the solid walls of the resonator. Thus, we can determine the bulk viscosity only when the boundary layer attenuation is small and well understood. We present a comparison of calculations and measurements of sound attenuation in the acoustic boundary layer of xenon near its liquid-vapor critical point.

Gillis, Keith A.; Shinder, Iosif I.; Moldover, Michael R.; Zimmerli, Gregory A.

2004-01-01

425

A study of xenon isotopes in a martian meteorite using the RELAX ultrasensitive mass spectrometer  

SciTech Connect

The Refrigerator Enhanced Analyser for Xenon (RELAX), an ultrasensitive resonance ionization time-of-flight mass spectrometer, has been used with a laser microprobe to investigate the isotopic composition of xenon trapped in the martian meteorite ALH84001. The laser microprobe has a spatial resolution of the order of 100{mu}m thus allowing the in situ analysis of individual mineral grains in a polished section when combined with ultrasensitive, low blank sample analysis. We present results showing that the mineral orthopyroxene in ALH84001 contains a trapped xenon component consistent with a martian origin. Additionally, a cosmic ray exposure age of 15Ma for ALH84001 is obtained from spallation derived xenon trapped within an apatite grain.

Whitby, J A; Gilmour, J D; Turner, G [Department of Earth Sciences, Manchester University, Oxford Road, Manchester M13 9PL (United Kingdom)

1997-01-15

426

Nonlinear dynamical behavior of Xenon atoms along dislocation lines in UO2+x nuclear fuel  

NASA Astrophysics Data System (ADS)

Experimental results showed that there are a few Xenon atom bubbles connected by the dislocation line in the UO2+x nuclear fuel, and the largest radius of bubbles is about 45 nm. This phenomenon is in contrast to traditional bubble formation mechanism. This phenomenon is very important in understanding the properties of nuclear fuel. In this work, we apply a time-dependent microscopic atom transport equation and take into account stress coherent potential in the boundary of the dislocation. Using the equation, we numerically solved the stress coherence effect and studied the transfer properties of Xenon atoms along the dislocation line. Our numerical results show that the transport of the Xenon atoms along the dislocation changes nonlinearly with the external driving energy, and reaches at the saturation values. It explains the growth limit of Xenon atom bubbles that is in agreement with the experiment results.

Sui, PengFei; Dai, ZhenHong

2015-01-01

427

Index of refraction, Rayleigh scattering length, and Sellmeier coefficients in solid and liquid argon and xenon  

E-print Network

Like all the noble elements, argon and xenon are scintillators, \\emph{i.e.} they produce light when exposed to radiation. Large liquid argon detectors have become widely used in low background experiments, including dark matter and neutrino research. However, the index of refraction of liquid argon at the scintillation wavelength has not been measured and current Rayleigh scattering length calculations disagree with measurements. Furthermore, the Rayleigh scattering length and index of refraction of solid argon and solid xenon at their scintillation wavelengths have not been previously measured or calculated. We introduce a new calculation using previously measured data in liquid and solid argon and xenon to extrapolate the optical properties at the scintillation wavelengths using the Sellmeier dispersion relationship. As a point of validation, we compare our extrapolated index of refraction for liquid xenon against the measured value and find agreement within the uncertainties. This method results in a Rayle...

Grace, Emily

2015-01-01

428

Detection of brown adipose tissue and thermogenic activity in mice by hyperpolarized xenon MRI.  

PubMed

The study of brown adipose tissue (BAT) in human weight regulation has been constrained by the lack of a noninvasive tool for measuring this tissue and its function in vivo. Existing imaging modalities are nonspecific and intrinsically insensitive to the less active, lipid-rich BAT of obese subjects, the target population for BAT studies. We demonstrate noninvasive imaging of BAT in mice by hyperpolarized xenon gas MRI. We detect a greater than 15-fold increase in xenon uptake by BAT during stimulation of BAT thermogenesis, which enables us to acquire background-free maps of the tissue in both lean and obese mouse phenotypes. We also demonstrate in vivo MR thermometry of BAT by hyperpolarized xenon gas. Finally, we use the linear temperature dependence of the chemical shift of xenon dissolved in adipose tissue to directly measure BAT temperature and to track thermogenic activity in vivo. PMID:25453088

Branca, Rosa Tamara; He, Ting; Zhang, Le; Floyd, Carlos S; Freeman, Matthew; White, Christian; Burant, Alex

2014-12-16

429

Results from the XENON10 Dark Matter search experiment at Gran Sasso Laboratories  

SciTech Connect

One of the most appealing questions in astroparticle physics concerns the nature of the Dark Matter (DM) particles and their possible interaction with ordinary matter. In order to find a solution to such problem, a double phase liquid-gas Xenon Time Projection Chamber has been proposed and built as a suitable detector for the direct detection of DM in the form of Weakly Interacting Massive Particles (WIMPs). The possibility of simultaneously measuring the scintillation and the ionization signals, and a 3D event localization feature, represent a powerful background discrimination method. During the Autumn-Winter 2006-2007 a prototype of 15 kg sensitive mass of Liquid Xenon (XENON10) has been successfully run at the Gran Sasso Underground Laboratory. The technique and the results of the XENON10 detector are presented.

Ferella, Alfredo Davide [RWTH Aachen University, Physics Department, Sommerfeldstr. 14, 52074 Aachen (Germany)

2007-11-20

430

Geologic Sequestration of Carbon Dioxide  

NASA Astrophysics Data System (ADS)

Geologic sequestration of carbon dioxide has emerged as one of the most promising options for making deep cuts in carbon dioxide emissions. Geologic sequestration involves the two-step process of first capturing carbon dioxide by separating it from stack emissions, followed by injection and long term storage in deep geologic formations. Sedimentary basins, including depleted oil and gas reservoirs, deep unminable coal seams, and brine-filled formations, provide the most attractive storage reservoirs. Over the past few years significant advances have been made in this technology, including development of simulation models and monitoring systems, implementation of commercial scale demonstration projects, and investigation of natural and industrial analogues for geologic storage of carbon dioxide. While much has been accomplished in a short time, there are many questions that must be answered before this technology can be employed on the scale needed to make significant reductions in carbon dioxide emissions. Questions such as how long must the carbon dioxide remain underground, to what extent will geochemical reactions completely immobilize the carbon dioxide, what can be done in the event that a storage site begins to leak at an unacceptable rate, what is the appropriate risk assessment, regulatory and legal framework, and will the public view this option favorably? This paper will present recent advances in the scientific and technological underpinnings of geologic sequestration and identify areas where additional information is needed.

Benson, S. M.

2003-04-01

431

Pulsed-discharge carbon dioxide lasers  

NASA Technical Reports Server (NTRS)

The purpose is to attempt a general introduction to pulsed carbon dioxide lasers of the kind used or proposed for laser radar applications. Laser physics is an excellent example of a cross-disciplinary topic, and the molecular spectroscopy, energy transfer, and plasma kinetics of the devices are explored. The concept of stimulated emission and population inversions is introduced, leading on to the molecular spectroscopy of the CO2 molecule. This is followed by a consideration of electron-impact pumping, and the pertinent energy transfer and relaxation processes which go on. Since the devices are plasma pumped, it is necessary to introduce a complex subject, but this is restricted to appropriate physics of glow discharges. Examples of representative devices are shown. The implications of the foregoing to plasma chemistry and gas life are discussed.

Willetts, David V.

1990-01-01

432

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

433

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

434

Optimal detectors for WIMP and 0–? ?? searches: Identical high-pressure xenon gas TPCs?  

Microsoft Academic Search

A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)—instead of liquid xenon (LXe)—appears likely to offer both superior energy resolution for the 0–? ?? decay search in 136Xe and superior ?-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0–? ?? decay detector design will realize an optimum design

David Nygren

2007-01-01

435

Optimal detectors for WIMP and 0 nu betabeta searches: Identical high-pressure xenon gas TPCs?  

Microsoft Academic Search

A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)---instead of liquid xenon (LXe)---appears likely to offer both superior energy resolution for the 0 nu betabeta decay search in 136Xe and superior gamma-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0 nu betabeta decay detector design will realize an

David Nygren

2007-01-01

436

A liquid xenon 3-dimensional imaging detector for MeV gamma-ray astrophysics  

Microsoft Academic Search

The experiment LXe-CAT (Liquid Xenon-Coded Aperture Telescope), which we have proposed for gamma-ray astrophysical observations in the 0.3-10 MeV energy range, uses a Liquid Xenon Time Projection Chamber (LXe-TPC) as a three-dimensional position sensitive gamma-ray detector, and a coded aperture mask to provide a telescope with an angular resolution of 30 arcmin over a field-of-view (FOV) of 19 deg x

Danli Chen

1994-01-01

437

GraXe, graphene and xenon for neutrinoless double beta decay searches  

Microsoft Academic Search

We propose a new detector concept, GraXe (to be pronounced as grace), to search for neutrinoless double beta decay in 136XE. GraXe combines a popular detection medium in rare-event searches, liquid xenon, with a new, background-free material, graphene.In our baseline design of GraXe, a sphere made of graphene-coated titanium mesh and filled with liquid xenon (LXe) enriched in the 136XE

J. J. Gómez-Cadenas; F. Guinea; M. M. Fogler; M. I. Katsnelson; J. Martín-Albo; F. Monrabal; J. Muñoz Vidal

2012-01-01

438

SAUNA—a 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 beta–gamma 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

439

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

440

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

441

Abatement of xenon and iodine emissions from medical isotope production facilities.  

PubMed

The capability of the International Monitoring System (IMS) to detect xenon from underground nuclear explosions is dependent on the radioactive xenon background. Adding to the background, medical isotope production (MIP) by fission releases several important xenon isotopes including xenon-133 and iodine-133 that decays to xenon-133. The amount of xenon released from these facilities may be equivalent to or exceed that released from an underground nuclear explosion. Thus the release of gaseous fission products within days of irradiation makes it difficult to distinguish MIP emissions from a nuclear explosion. In addition, recent shortages in molybdenum-99 have created interest and investment opportunities to design and build new MIP facilities in the United States and throughout the world. Due to the potential increase in the number of MIP facilities, a discussion of abatement technologies provides insight into how the problem of emission control from MIP facilities can be tackled. A review of practices is provided to delineate methods useful for abatement of medical isotopes. PMID:24418952

Doll, Charles G; Sorensen, Christina M; Bowyer, Theodore W; Friese, Judah I; Hayes, James C; Hoffmann, Emmy; Kephart, Rosara

2014-04-01

442

Abatement of Xenon and Iodine Emissions from Medical Isotope Production Facilities  

SciTech Connect

The capability of the International Monitoring System (IMS) to detect xenon from underground nuclear explosions is dependent on the radioactive xenon background. Adding to the background, medical isotope production (MIP) by fission releases several important xenon isotopes including xenon-133 and iodine-133 that decays to xenon-133. The amount of xenon released from these facilities may be equivalent to or exceed that released from an underground nuclear explosion. Thus the release of gaseous fission products within days of irradiation makes it difficult to distinguish MIP emissions from a nuclear explosion. In addition, recent shortages in molybdenum-99 have created interest and investment opportunities to design and build new MIP facilities in the United States and throughout the world. Due to the potential increase in the number of MIP facilities, a discussion of abatement technologies provides insight into how the problem of emission control from MIP facilities can be tackled. A review of practices is provided to delineate methods useful for abatement of medical isotopes.

Doll, Charles G. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Sorensen, Christina M. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Bowyer, Ted W. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Friese, Judah I. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Hayes, James C. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Hoffman, Emma L. [Australian Nuclear Science and Technology Organisation, Menai (Australia); Kephart, Rosara F. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

2014-04-01

443

Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experiment  

NASA Astrophysics Data System (ADS)

XENON is a dark matter direct detection project, consisting of a time projection chamber (TPC) filled with liquid xenon as detection medium. The construction of the next generation detector, XENON1T, is presently taking place at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. It aims at a sensitivity to spin-independent cross sections of 2 · 10-47 c 2 for WIMP masses around 50 GeV2, which requires a background reduction by two orders of magnitude compared to XENON100, the current generation detector. An active system that is able to tag muons and muon-induced backgrounds is critical for this goal. A water Cherenkov detector of ~ 10 m height and diameter has been therefore developed, equipped with 8 inch photomultipliers and cladded by a reflective foil. We present the design and optimization study for this detector, which has been carried out with a series of Monte Carlo simulations. The muon veto will reach very high detection efficiencies for muons (>99.5%) and showers of secondary particles from muon interactions in the rock (>70%). Similar efficiencies will be obtained for XENONnT, the upgrade of XENON1T, which will later improve the WIMP sensitivity by another order of magnitude. With the Cherenkov water shield studied here, the background from muon-induced neutrons in XENON1T is negligible.

Aprile, E.; Agostini, F.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Auger, M.; Balan, C.; Barrow, P.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Breskin, A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Cardoso, J. M. R.; Colijn, A. P.; Contreras, H.; Cussonneau, J. P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; Itay, R.; Kaether, F.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Le Calloch, M.; Lellouch, D.; Levinson, L.; Levy, C.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Lyashenko, A.; MacMullin, S.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Mayani Paras, D.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Miguez, B.; Molinario, A.; Morana, G.; Murra, M.; Naganoma, J.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Piastra, F.; Pienaar, J.; Plante, G.; Priel, N.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

2014-11-01

444

Xenon Treatment Protects Against Cold Ischemia Associated Delayed Graft Function and Prolongs Graft Survival in Rats  

PubMed Central

Prolonged hypothermic storage causes ischemia-reperfusion injury (IRI) in the renal graft, which is considered to contribute to the occurrence of the delayed graft function (DGF) and chronic graft failure. Strategies are required to protect the graft and to prolong renal graft survival. We demonstrated that xenon exposure to human proximal tubular cells (HK-2) led to activation of range of protective proteins. Xenon treatment prior to or after hypothermia–hypoxia challenge stabilized the HK-2 cellular structure, diminished cytoplasmic translocation of high-mobility group box (HMGB) 1 and suppressed NF-?B activation. In the syngeneic Lewis-to-Lewis rat model of kidney transplantation, xenon exposure to donors before graft retrieval or to recipients after engraftment decreased caspase-3 expression, localized HMGB-1 within nuclei and prevented TLR-4/NF-?B activation in tubular cells; serum pro-inflammatory cytokines IL-1?, IL-6 and TNF-? were reduced and renal function was preserved. Xenon treatment of graft donors or of recipients prolonged renal graft survival following IRI in both Lewis-to-Lewis isografts and Fischer-to-Lewis allografts. Xenon induced cell survival or graft functional recovery was abolished by HIF-1? siRNA. Our data suggest that xenon treatment attenuates DGF and enhances graft survival. This approach could be translated into clinical practice leading to a considerable improvement in long-term graft survival. PMID:23710625

Zhao, H; Watts, H R; Chong, M; Huang, H; Tralau-Stewart, C; Maxwell, P H; Maze, M; George, A J T; Ma, D

2013-01-01

445

Design and construction of a cryogenic distillation device for removal of krypton for liquid xenon dark matter detectors.  

PubMed

Liquid xenon (Xe) is one of the commendable detecting media for the dark matter detections. However, the small content of radioactive krypton-85 ((85)Kr) always exists in the commercial xenon products. An efficient cryogenic distillation system to remove this krypton (Kr) from commercial xenon products has been specifically designed, developed, and constructed in order to meet the requirements of the dark matter experiments with high- sensitivity and low-background. The content of krypton in regular commercial xenon products can be reduced from 10(-9) to 10(-12), with 99% xenon collection efficiency at maximum flow rate of 5 kg/h (15SLPM). The purified xenon gases produced by this distillation system can be used as the detecting media in the project of Panda X, which is the first dark matter detector developed in China. PMID:24517821

Wang, Zhou; Bao, Lei; Hao, Xihuan; Ju, Yonglin

2014-01-01

446

Reducing carbon dioxide to products  

DOEpatents

A method reducing carbon dioxide to one or more products may include steps (A) to (C). Step (A) may bubble said carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode may reduce said carbon dioxide into said products. Step (B) may adjust one or more of (a) a cathode material, (b) a surface morphology of said cathode, (c) said electrolyte, (d) a manner in which said carbon dioxide is bubbled, (e), a pH level of said solution, and (f) an electrical potential of said divided electrochemical cell, to vary at least one of (i) which of said products is produced and (ii) a faradaic yield of said products. Step (C) may separate said products from said solution.

Cole, Emily Barton; Sivasankar, Narayanappa; Parajuli, Rishi; Keets, Kate A

2014-09-30

447

NASA Satellite Sees Carbon Dioxide  

NSDL National Science Digital Library

In this problem set, learners will analyze a map of atmospheric carbon dioxide derived from satellite data. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

448

Carbon Dioxide and Ocean Acidification  

NSDL National Science Digital Library

Demonstrates the affect of increased dissolved carbon dioxide on water pH using a cheap, non-toxic acid/base indicator. Students bubble breath through a straw into red cabbage juice and note the color change.

Chris Lewis

449

Tunable V.U.V. radiation generated by non-resonant phase matched odd harmonic generation in xenon gas  

E-print Network

in xenon gas Tran ba' Chu (1,*), A. Bouvier (1), A. J. Bouvier (1) and R. Fischer (2) (1) Laboratoire de.U.V. radiation has been generated by non-resonant fifth-harmonic generation in xenon in the domain 1135-1170 Ã?) of the xenon gas is of the order of 10-47 e.s.u. J. Phys. France 49 (1988) 1725-1729 OCTOBRE 1988

Boyer, Edmond

450

Recuperative supercritical carbon dioxide cycle  

DOEpatents

A power plant includes a closed loop, supercritical carbon dioxide system (CLS-CO.sub.2 system). The CLS-CO.sub.2 system includes a turbine-generator and a high temperature recuperator (HTR) that is arranged to receive expanded carbon dioxide from the turbine-generator. The HTR includes a plurality of heat exchangers that define respective heat exchange areas. At least two of the heat exchangers have different heat exchange areas.

Sonwane, Chandrashekhar; Sprouse, Kenneth M; Subbaraman, Ganesan; O'Connor, George M; Johnson, Gregory A

2014-11-18

451

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

452

The effects of xenon on myogenic motor evoked potentials in rabbits: a comparison with propofol and isoflurane.  

PubMed

We compared the effects of xenon on myogenic motor evoked potentials (MEPs) with those of propofol and isoflurane in rabbits under ketamine/fentanyl anesthesia. Thirty animals were randomly allocated to one of 3 groups (n = 10 in each group). In the propofol group, propofol was administered at a rate of 0.4 mg x kg(-1) x min(-1) (small) and 0.8 mg x kg(-1) x min(-1) (large). In the isoflurane group, isoflurane was administered at 0.8% (small) and 1.6% (large). In the xenon group, xenon was administered at 35% (small) and 70% (large). Myogenic MEPs in response to stimulation with single pulse and a train of 5 pulses were recorded from the soleus muscle before, during (at small and large doses), and after the administration of each anesthetic. With single-pulse stimulation, MEPs were recorded in 90% and 50% of animals at small and large doses of xenon, respectively, and MEP amplitudes in the xenon and isoflurane groups were significantly lower compared with those in the propofol group. With train pulse stimulation, MEPs were recorded in 100% and 90% of animals at small and large doses of xenon, respectively, and a reduction in MEP amplitudes by xenon was more prominent than by propofol but less than isoflurane at large doses. These results suggest that MEP recording may be feasible under xenon anesthesia if multipulse stimulation is used, although xenon has suppressive effects on myogenic MEPs. PMID:16717315

Yamamoto, Yuri; Kawaguchi, Masahiko; Kakimoto, Meiko; Takahashi, Masahiro; Inoue, Satoki; Goto, Takahisa; Furuya, Hitoshi

2006-06-01

453

Molecular simulations of carbon dioxide and water: cation solvation.  

PubMed

Proposed carbon dioxide sequestration scenarios in sedimentary reservoirs require investigation into the interactions between supercritical carbon dioxide, brines, and the mineral phases found in the basin and overlying caprock. Molecular simulations can help to understand the partitioning of metal cations between aqueous solutions and supercritical carbon dioxide where limited experimental data exist. In this effort, we used classical molecular dynamics simulations to compare the solvation of alkali and alkaline-earth metal cations in water and liquid CO(2) at 300 K by combining a flexible simple point charge model for water and an accurate flexible force field for CO(2). Solvation energies for these cations are larger in water than in carbon dioxide, suggesting that they will partition preferentially into water. In both aqueous and CO(2) solutions, the solvation energies decrease with cation size and increase with cation charge. However, changes in solvation energy with ionic radii are smaller in CO(2) than in water suggesting that the partitioning of cations into CO(2) will increase with ion size. Simulations of the interface between aqueous solution and supercritical CO(2) support this suggestion in that some large cations (e.g., Cs(+) and K(+)) partition into the CO(2) phase, often with a partial solvation sphere of water molecules. PMID:22779448

Criscenti, Louise J; Cygan, Randall T

2013-01-01

454

Gamma background studies for the XENON experiment using a High Purity Germanium Detector  

NASA Astrophysics Data System (ADS)

The XENON Dark Matter Experiment, deployed at the Gran Sasso National Laboratory in Italy on March 2006, is a liquid noble gas detector designed to directly detect dark matter. The detector uses a dual-phase (gas/liquid) Xenon target to search for nuclear recoils associated with nucleus-WIMP interactions. Due to the high sensitivity needed in such an experiment, it is vital to not only reduce the background but to also understand the remaining background so as to aid in the understanding of the data as well as to facilitate upgrades beyond the early Research and Development phases. Many of the components of the XENON10 detector have been screened using a High Purity Germanium Detector known as the GATOR detector. Full analysis of the screening data requires Monte Carlo simulations of the GATOR detector and the sample. Results from this screening will be presented. Using the information obtained from the screening operation, Monte Carlo simulations of the XENON10 electron recoil background will be examined and compared to the actual detector data. The success of this simulation to data comparison indicates that we have a good understanding of the XENON10 gamma background and will be able to make more informed decisions regarding the next stage of detector development. This type of analysis has aided in the selection and design of many of the materials and components being incorporated into the new XENON100 detector, the next generation detector which will be capable of improving the limit set by XENON10 by at least an order of magnitude. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http:/ /www.uflib.ufl.edu/etd.html)

Angle, Jesse Isaac

455

Response of liquid xenon to Compton electrons down to 1.5 keV  

NASA Astrophysics Data System (ADS)

The response of liquid xenon to low-energy electronic recoils is relevant in the search for dark-matter candidates which interact predominantly with atomic electrons in the medium, such as axions or axionlike particles, as opposed to weakly interacting massive particles which are predicted to scatter with atomic nuclei. Recently, liquid-xenon scintillation light has been observed from electronic recoils down to 2.1 keV, but without applied electric fields that are used in most xenon dark-matter searches. Applied electric fields can reduce the scintillation yield by hindering the electron-ion recombination process that produces most of the scintillation photons. We present new results of liquid xenon’s scintillation emission in response to electronic recoils as low as 1.5 keV, with and without an applied electric field. At zero field, a reduced scintillation output per unit deposited energy is observed below 10 keV, dropping to nearly 40% of its value at higher energies. With an applied electric field of 450V/cm, we observe a reduction of the scintillation output to about 75% relative to the value at zero field. We see no significant energy dependence of this value between 1.5 and 7.8 keV. With these results, we estimate the electronic-recoil energy thresholds of ZEPLIN-III, XENON10, XENON100, and XMASS to be 2.8, 2.5, 2.3, and 1.1 keV, respectively, validating their excellent sensitivity to low-energy electronic recoils.

Baudis, L.; Dujmovic, H.; Geis, C.; James, A.; Kish, A.; Manalaysay, A.; Marrodán Undagoitia, T.; Schumann, M.

2013-06-01

456

Xenon-nitrogen chemistry: gas-phase generation and theoretical investigation of the xenon-difluoronitrenium ion F2N-Xe+.  

PubMed

The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (?H and ?G) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions. PMID:21826753

Operti, Lorenza; Rabezzana, Roberto; Turco, Francesca; Borocci, Stefano; Giordani, Maria; Grandinetti, Felice

2011-09-12

457

Water Molecule Residence Times  

NSDL National Science Digital Library

How long will a molecule of Water stay in a particular reservoir? What is the average time a molecule of Water will stay in an ocean? What is the average time a molecule of water will stay in a river? A lake? As groundwater? A glacier? How long will a water vapor molecule stay suspended in the atmosphere? Why is the residence ...

Science, Sill -.

2010-11-16

458

Monte Carlo Study of a Xenon Advanced Compton Telescope  

NASA Astrophysics Data System (ADS)

As part of the Advanced Compton Telescope (ACT) study, we have simulated the performance of a double scatter telescope concept based on liquid xenon time projection chamber (LXeTPC) modules, arranged to cover the large geometrical area required by the demanding ACT sensitivity while maintaining excellent efficiency and background rejection capability. The unitary TPC module is similar in size to the detector successfully developed and tested as balloon borne Compton telescope prototype within the LXeGRIT program. Compared with this prototype, however, the energy resolution is dramatically improved, by fully exploiting both the ionization and the fast scintillation signals available in LXe, with optimized readout schemes. The excellent coincidence timing measured with compact phototubes operating in the liquid allows to re-introduce a time-of-flight (TOF) measurement, in a COMPTEL like D1/D2 configuration but with less than 20 cm separation between the two detector arrays. We will show results from a Monte Carlo study of a XeACT, which combines the intrinsic strength of large volume, fully homogeneous, 3D position sensitive detectors like TPCs, with the additional background rejection power and unique event sequencing of a TOF measurement.

Aprile, E.; Curioni, A.; Giboni, K. L.; Yamashita, M.; Zhang, S.; Oberlack, U.

2004-08-01

459

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

460

Excimer emission from pulsed microhollow cathode discharges in xenon  

SciTech Connect

Direct current (dc) microhollow cathode discharge (MHCD) is an intense source for excimer radiation in vacuum ultraviolet at a wavelength of 172 nm in a high pressure xenon (Xe) gas. The concentration of precursors for the excimer formation, i.e., excited and ionized gas atoms, increases significantly by applying high voltage pulse onto the dc MHCD over the pulse duration range from 20 to 100 ns. The intensity of the excimer emission for the voltage pulse of 20 ns duration exceeds that of the emission intensity obtained from the same MHCD operated only in the dc mode, by one order of magnitude. In addition, the emission intensity increases by one order of magnitude over the pulse duration range from 20 to 100 ns. It can be assumed that the emission intensity of the MHCD source increases as long as the duration of the high voltage pulse is shorter than the electron relaxation time. For the high voltage pulse of 100 ns duration, the emission intensity has been found to be further enhanced by a factor of three when the gas pressure is increased from 200 to 800 mbar.

Lee, B.-J.; Nam, S. H. [Pohang Accelerator Laboratory, Pohang, Kyungbuk 790-784 (Korea, Republic of)] [Pohang Accelerator Laboratory, Pohang, Kyungbuk 790-784 (Korea, Republic of); Rahaman, H. [CSIR–CEERI Pilani, Rajasthan 333031 (India)] [CSIR–CEERI Pilani, Rajasthan 333031 (India); Iberler, M.; Jacoby, J. [Institute of Applied Physics, Goethe University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)] [Institute of Applied Physics, Goethe University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Frank, K. [Physics Department 1, University of Erlangen – Nuremberg, 91058 Erlangen (Germany)] [Physics Department 1, University of Erlangen – Nuremberg, 91058 Erlangen (Germany)

2013-12-15

461

Conceptual Design of the Nuclear Electronic Xenon Ion System (NEXIS)  

NASA Technical Reports Server (NTRS)

In support of the NEXIS program, Aerojet-Redmond Operations, with review and input from the JPL and Boeing, has completed the design for a development model (DM) discharge chamber assembly and main discharge cathode assembly. These efforts along with the work by JPL to develop the carbon-carbon-composite ion optics assembly have resulted in a complete ion engine design. The goal of the NEXIS program is to significantly advance the current state of the art by developing an ion engine capable of operating at an input power of 20kW, an Isp of 7500 sec and have a total xenon through put capability of 2000 kg. In this paper we will describe the methodology used to design the discharge chamber and cathode assemblies and describe the resulting final design. Specifics will include the concepts used for the mounting of the ion optics along with the concepts used for the gimbal mounts. In addition, we will present results of a vibrational analysis showing how the engine will respond to a typical Delta IV heavy vibration spectrum.

Monheiser, Jeff; Polk, Jay; Randolph, Tom

2004-01-01

462

Axial Magnetic Field Effects on Xenon Short-Arc Lamps  

NASA Astrophysics Data System (ADS)

The effect of an axial magnetic field (AMF) on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 mT, the visible radiation power and electric power ascend more than 80% and 70% respectively, and the radiation efficiency is improved by 23% for the best increment at 12 mT AMF. The measurement of radiation intensity shows that the increment of radiation intensity comes mostly from the plasma area close to the cathode tip, and partially from the other area of the arc column. Successive images of the arc indicate that the arc column not only rotates about its axis, but revolves around the axis of electrodes with the AMF. The arc column structure is constricted, distorted and elongated as the AMF increases. It is suggested that the improvements of the radiation intensity and radiation efficiency are attributed to the constriction of the arc column, which is mainly induced by the enhanced cathode jet.

Wang, Cheng; Chen, Tang; Li, Wanwan; Zha, Jun; Xia, Weidong

2014-12-01

463

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

464

Thrust Stand Characterization of the NASA Evolutionary Xenon Thruster (NEXT)  

NASA Technical Reports Server (NTRS)

Direct thrust measurements have been made on the NASA Evolutionary Xenon Thruster (NEXT) ion engine using a standard pendulum style thrust stand constructed specifically for this application. Values have been obtained for the full 40-level throttle table, as well as for a few off-nominal operating conditions. Measurements differ from the nominal NASA throttle table 10 (TT10) values by 3.1 percent at most, while at 30 throttle levels (TLs) the difference is less than 2.0 percent. When measurements are compared to TT10 values that have been corrected using ion beam current density and charge state data obtained at The Aerospace Corporation, they differ by 1.2 percent at most, and by 1.0 percent or less at 37 TLs. Thrust correction factors calculated from direct thrust measurements and from The Aerospace Corporation s plume data agree to within measurement error for all but one TL. Thrust due to cold flow and "discharge only" operation has been measured, and analytical expressions are presented which accurately predict thrust based on thermal thrust generation mechanisms.

Diamant, Kevin D.; Pollard, James E.; Crofton, Mark W.; Patterson, Michael J.; Soulas, George C.

2010-01-01

465

First Detection of Krypton and Xenon in a White Dwarf  

NASA Technical Reports Server (NTRS)

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-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 plus or minus 0.5 and log Xe = -4.2 plus or minus 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 thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

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

2012-01-01

466

Reactivity of xenon with ice at planetary conditions.  

PubMed

We report results from high pressure and temperature experiments that provide evidence for the reactivity of xenon with water ice at pressures above 50 GPa and a temperature of 1500 K-conditions that are found in the interiors of Uranus and Neptune. The x-ray data are sufficient to determine a hexagonal lattice with four Xe atoms per unit cell and several possible distributions of O atoms. The measurements are supplemented with ab initio calculations, on the basis of which a crystallographic structure with a Xe4O12H12 primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and ?-O2, and has the same oxygen subnetwork as the latter. Furthermore, it has a weakly metallic character and likely undergoes sublattice melting of the H subsystem. Our findings indicate that Xe is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth. PMID:23848893

Sanloup, Chrystèle; Bonev, Stanimir A; Hochlaf, Majdi; Maynard-Casely, Helen E

2013-06-28

467

Extended-testing of xenon ion thruster hollow cathodes  

NASA Technical Reports Server (NTRS)

A hollow cathode wear-test of 508 hours was successfully completed at an emission current of 23.0 A and a xenon flow rate of 10 Pa-L/s. This test was the continuation of a hollow cathode contamination investigation. Discharge voltage was stable at 16.7 V. The cathode temperature averaged 1050 C with a 7 percent drop during the wear-test. Discharge ignition voltage was found to be approximately 20 V and was repeatable over four starts. Post-test analyses of the hollow cathode found a much improved internal cathode condition with respect to earlier wear-test cathodes. Negligible tungsten movement occurred and no formation of mono-barium tungsten was observed. These results correlated with an order-of-magnitude reduction in propellant feed-system leakage rate. Ba2CaWO6 and extensive calcium crystal formation occurred on the upstream end of the insert. Ba-Ca compound depositions were found on the Mo insert collar, on the Re electrical leads, and in the gap between the insert and cathode wall. This wear-test cathode was found to be in the best internal condition and had the most stable operating performance of any hollow cathode tested during this contamination investigation.

Sarver-Verhey, Timothy R.

1992-01-01

468

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

469

Molecule of the Month  

NSDL National Science Digital Library

From the University of Bristol's School of Chemistry, this site features a new molecule each month. For example, the molecule for April is Melatonin. Each molecule comes with a link to a Webpage from a university or commercial site containing further information. (Links may require Chime, VRML, or Java.) Contributors may submit molecule pages to be considered in future months. Monthly molecules date back to January 1996.

470

Temperature and pressure dependence of the optical Kerr effect in liquid and gaseous carbon dioxide  

Microsoft Academic Search

Optical Kerr effect investigation in liquid and gaseous carbon dioxide and the temperature dependence of this effect are reported. Using the method of indirect comparison of the results of the optical Kerr effect in liquids and gases it is found that the contribution to optical birefringence from a single CO2 molecule in the gas and vapor phase is about 7

Z. Blaszczak; P. Gauden

1992-01-01

471

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

472

Measurement of xenon plasma properties in an ion thruster using laser Thomson scattering technique  

SciTech Connect

This paper reports on the development of a method for measuring xenon plasma properties using the laser Thomson scattering technique, for application to ion engine system design. The thresholds of photo-ionization of xenon plasma were investigated and the number density of metastable atoms, which are photo-ionized by a probe laser, was measured using laser absorption spectroscopy, for several conditions. The measured threshold energy of the probe laser using a plano-convex lens with a focal length of 200 mm was 150 mJ for a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W; the probe laser energy was therefore set as 80 mJ. Electron number density was found to be (6.2 {+-} 0.4) Multiplication-Sign 10{sup 17} m{sup -3} and electron temperature was found to be 2.2 {+-} 0.4 eV at a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W. The threshold of the probe laser intensity against photo-ionization in a miniature xenon ion thruster is almost constant for various mass flow rates, since the ratio of population of the metastable atoms to the electron number density is little changed.

Yamamoto, N.; Tomita, K.; Sugita, K.; Kurita, T.; Nakashima, H.; Uchino, K. [Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka 816-8580 (Japan)

2012-07-15

473

First Results from the XENON10 Dark Matter Experiment the Gran Sasso Underground Lab  

NASA Astrophysics Data System (ADS)

We report the first results from a search for Weakly Interacting Massive Particles (WIMPs) with the XENON10 experiment operating underground at the Gran Sasso Laboratory. XENON10 is the first dual phase xenon time projection chamber (XeTPC) module realized within the XENON program. The 3D-postion sensitive detector has an active mass of 15 kg of liquid xenon, viewed by two arrays of compact photomultipliers, to measure simultaneously the scintillation and the ionization, via proportional scintillation in the gas. Background rejection on an event-by-event basis is achieved through this measurement and 3D event localization. The detector was deployed underground in Spring 2006 and mounted in its shield in Summer 2006. The experiment has been operating continuously for the past five months, with a high degree of stability and very good performance. The energy threshold is <10 keV and the background rate is <1evt/kg/keV/day. In-situ gamma and neutron calibrations have been carried out to define event selection and energy threshold for nuclear recoil candidates. Data taking continues as of this writing. A blind analysis on the latest months of data is currently being performed using only calibration data. WIMP search results are expected by early Spring 2007.

Aprile, Elena

2007-04-01

474

Development of a high-resolution liquid xenon detector for gamma-ray astrophysics  

NASA Astrophysics Data System (ADS)

It has been shown here that liquid xenon is one of the most promising detector media for future gamma-ray detectors, owing to an excellent combination of physical properties. The feasibility of the construction of a high resolution liquid xenon detector as a gamma-ray detector for astrophysics has been demonstrated. Up to 3.5 liters of liquid xenon has been successfully purified and using both small and large volume prototypes, the charge and the energy resolution response of such detectors to gamma-rays, internal conversion electrons and alpha particles have been measured. The best energy resolution measured was 4.5 percent FWHM at 1 MeV. Cosmic ray tracks have been imaged using a 2-dimensional liquid xenon multiwire imaging chamber. The spatial resolution along the direction of the drifting electrons was 180 microns rms. Experiments have been performed to study the scintillation light in liquid xenon, as the prompt scintillation signal in the liquid is an electron-ion pair in liquid krypton was measured for the first time with a pulsed ionization chamber to be 18.4 plus or minus 0.3 eV.

Mukherjee, Reshmi

475

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

476

Molecular Structure of Carbon Dioxide  

NSDL National Science Digital Library

Carbon dioxide was first described in the 17th century by Jan Baptist van Helmont, a Belgium chemist. The chemical CO2 is released into the atmosphere when carbon-containing fossil fuels like oil, natural gas, and coal are burned in air. It is also produced by various microorganisms in fermentation and is breathed out by animals. Plants absorb carbon dioxide during photosynthesis, using both the carbon and the oxygen to construct carbohydrates. Every year the amount of CO2 in the atmosphere is increasing. CO2 build-up in the atmosphere is caused by deforestation, therefore reducing the number of trees available to absorb CO2. Excess CO2 in the environment causes Global Warming and the Greenhouse Effect. It is also toxic to humans since inhalation of large amounts of CO2 can cause suffocation. Some beverages, such as beer and sparkling wine contain carbon dioxide as a result of fermentation.

2002-08-15

477

Magnesite disposal of carbon dioxide  

SciTech Connect

In this paper we report our progress on developing a method for carbon dioxide disposal whose purpose it is to maintain coal energy competitive even is environmental and political pressures will require a drastic reduction in carbon dioxide emissions. In contrast to most other methods, our approach is not aiming at a partial solution of the problem, or at buying time for phasing out fossil energy. Instead, its purpose is to obtain a complete and economic solution of the problem, and thus maintain access to the vast fossil energy reservoir. A successful development of this technology would guarantee energy availability for many centuries even if world economic growth the most optimistic estimates that have been put forward. Our approach differs from all others in that we are developing an industrial process which chemically binds the carbon dioxide in an exothermic reaction into a mineral carbonate that is thermodynamically stable and environmentally benign.

Lackner, K.S.; Butt, D.P.; Wendt, C.H.

1997-08-01

478

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

DOEpatents

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 (/sup 211/Rn) and Xenon-125 (/sup 125/Xe) including a one-step chemical procedure following an irradiation procedure in which a selected target of Thorium (/sup 232/Th) or Uranium (/sup 238/U) is irradiated. The disclosed method is also effective for the preparation in a one-step chemical procedure of substantially equal amounts of high purity /sup 123/I and /sup 211/At. In one preferred arrangement of the invention almost equal quantities of /sup 211/Rn and /sup 125/Xe are prepared using a onestep chemical procedure in which a suitably irradiated fertile target material, such as thorium-232 or uranium-238, is treated to extract those radionuclides from it. In the same one-step chemical procedure about equal quantities of /sup 211/At and /sup 123/I are prepared and stored for subsequent use. In a modified arrangement of the method of the invention, it is practiced to separate and store about equal amounts of only /sup 211/Rn and /sup 125/Xe, while preventing the extraction or storage of the radionuclides /sup 211/At and /sup 123/I.

Mirzadeh, S.; Lambrecht, R.M.

1985-07-01

479

Novel nuclear magnetic resonance techniques for studying biological molecules  

SciTech Connect

Over the fifty-five year history of Nuclear Magnetic Resonance (NMR), considerable progress has been made in the development of techniques for studying the structure, function, and dynamics of biological molecules. The majority of this research has involved the development of multi-dimensional NMR experiments for studying molecules in solution, although in recent years a number of groups have begun to explore NMR methods for studying biological systems in the solid-state. Despite this new effort, a need still exists for the development of techniques that improve sensitivity, maximize information, and take advantage of all the NMR interactions available in biological molecules. In this dissertation, a variety of novel NMR techniques for studying biomolecules are discussed. A method for determining backbone ({phi}/{psi}) dihedral angles by comparing experimentally determined {sup 13}C{sub a}, chemical-shift anisotropies with theoretical calculations is presented, along with a brief description of the theory behind chemical-shift computation in proteins and peptides. The utility of the Spin-Polarization Induced Nuclear Overhauser Effect (SPINOE) to selectively enhance NMR signals in solution is examined in a variety of systems, as are methods for extracting structural information from cross-relaxation rates that can be measured in SPINOE experiments. Techniques for the production of supercritical and liquid laser-polarized xenon are discussed, as well as the prospects for using optically pumped xenon as a polarizing solvent. In addition, a detailed study of the structure of PrP 89-143 is presented. PrP 89-143 is a 54 residue fragment of the prion proteins which, upon mutation and aggregation, can induce prion diseases in transgenic mice. Whereas the structure of the wild-type PrP 89-143 is a generally unstructured mixture of {alpha}-helical and {beta}-sheet conformers in the solid state, the aggregates formed from the PrP 89-143 mutants appear to be mostly {beta}-sheet.

Laws, David D.

2000-06-01

480

Abstract--A Time to Digital Converter was designed (CMOS 0.35 m) in order to be used in Liquid Xenon PET prototype.  

E-print Network

Xenon PET prototype. The circuit proved to be able to work at -120°C, while showing a resolution of 250 of Liquid Xenon (LXe) for small animal tomography [1]. The advantage of this scintillator is to have a high of the Field Of View. When a gamma particle hits the Xenon, light is emitted on all direction

Paris-Sud XI, Université de