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Sample records for aerodyne high-resolution time-of-flight

  1. Studies of Chamber Organic Aerosol Using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Chhabra, Puneet Singh

    Secondary organic aerosol (SOA) contributes a substantial fraction to total ambient particulate mass. SOA is a complex mixture of different organic species formed via many gas- and particle-phase reaction pathways. The Aerodyne aerosol mass spectrometer (AMS) has become a standard tool in measuring the bulk chemical composition of SOA in realtime. In addition to acquiring mass spectra of SOA, the high-resolution time-of-flight AMS, or HR-ToF-AMS, can distinguish and quantify ions with the same nominal mass but different elemental compositions. This thesis presents results from several studies in which the HR-ToF-AMS is used to chemically characterize SOA generated in chamber experiments. Glyoxal is a common oxidation product of both biogenic and anthropogenic volatile organic compounds (VOCs) and is known to partition into wet inorganic aerosol. Chamber studies of glyoxal uptake onto ammonium sulfate aerosol are conducted to better understand the mechanisms controlling glyoxal uptake onto ambient aerosol. Organic growth due to glyoxal uptake was found to be reversible under dark conditions. HR-ToF-AMS spectra provide evidence for glyoxal dimers and trimers existing in the particle phase. HR-ToF-AMS spectra indicate the irreversible formation of carbon-nitrogen compounds in the aerosol. Organosulfates are not detected under dark conditions; however, active photochemistry was found to occur within aerosol during irradiated experiments. Carboxylic acids and organic esters are identified within the aerosol. An organosulfate, which had been previously assigned as glyoxal sulfate in ambient samples and chamber studies of isoprene oxidation, is observed only in the irradiated experiments. Comparison with a laboratory-synthesized standard and chemical considerations strongly suggest that this organosulfate is glycolic acid sulfate, an isomer of the previously proposed glyoxal sulfate. Developments in HR-ToF-AMS data analysis have allowed for the measurement of the

  2. Recipes for high resolution time-of-flight detectors

    SciTech Connect

    Anz, S.J. |; Felter, T.E.; Hess, B.V.; Daley, R.S.; Roberts, M.L.; Williams, R.S.

    1995-01-01

    The authors discuss the dynamics, construction, implementation and benefits of a time-of-flight (TOF) detector with count rates an order of magnitude higher and resolution three to four times better than that obtainable with a surface barrier detector. The propose use of design criteria for a time-of-flight detector is outlined, and the determination of a TOF detector`s total relative timing error and how this value determines the mass resolution are illustrated using a graphical analysis. They present simulation and experimental examples employing light ions and discuss advantages and pitfalls of medium-energy heavy ion TOF spectrometry.

  3. Highly segmented, high resolution time-of-flight system

    SciTech Connect

    Nayak, T.K.; Nagamiya, S.; Vossnack, O.; Wu, Y.D.; Zajc, W.A.; Miake, Y.; Ueno, S.; Kitayama, H.; Nagasaka, Y.; Tomizawa, K.; Arai, I.; Yagi, K

    1991-12-31

    The light attenuation and timing characteristics of time-of-flight counters constructed of 3m long scintillating fiber bundles of different shapes and sizes are presented. Fiber bundles made of 5mm diameter fibers showed good timing characteristics and less light attenuation. The results for a 1.5m long scintillator rod are also presented.

  4. The high-resolution time-of-flight spectrometer TOFTOF

    NASA Astrophysics Data System (ADS)

    Unruh, Tobias; Neuhaus, Jürgen; Petry, Winfried

    2007-10-01

    The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of ˜1010n/cm2/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.

  5. Characterization of organic aerosols in Beijing using an aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Junke; Wang, Yuesi; Huang, Xiaojuan; Liu, Zirui; Ji, Dongsheng; Sun, Yang

    2015-06-01

    Fine particle of organic aerosol (OA), mostly arising from pollution, are abundant in Beijing. To achieve a better understanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Research Inc., USA) was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30±30 μg m-3, which was higher than in summer (13±6.9 μg m-3). The elemental analysis found that OA was more aged in summer (oxygen-to-carbon (O/C) ratios were 0.41 and 0.32 for summer and autumn, respectively). Positive matrix factorization (PMF) analysis identified three and five components in summer and autumn, respectively. In summer, an oxygenated OA (OOA), a cooking-emission-related OA (COA), and a hydrocarbon-like OA (HOA) were indentified. Meanwhile, the OOA was separated into LV-OOA (low-volatility OOA) and SV-OOA (semi-volatile OOA); and in autumn, a nitrogen-containing OA (NOA) was also found. The SOA (secondary OA) was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components, especially the POA (primary OA), in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.

  6. New high-resolution electrostatic ion mass analyzer using time of flight

    NASA Technical Reports Server (NTRS)

    Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Lundgren, R. A.; Sheldon, R. B.

    1990-01-01

    The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

  7. A high-resolution time-of-flight mass spectrometer for the detection of ultracold molecules

    NASA Astrophysics Data System (ADS)

    Kraft, S. D.; Mikosch, J.; Staanum, P.; Deiglmayr, J.; Lange, J.; Fioretti, A.; Wester, R.; Weidemüller, M.

    2007-12-01

    We have realized a high-resolution time-of-flight mass spectrometer combined with a magneto-optical trap. The spectrometer enables excellent optical access to the trapped atomic cloud using specifically devised acceleration and deflection electrodes. The ions are extracted along a laser beam axis and deflected onto an off-axis detector. The setup is applied to detect atoms and molecules photoassociated from ultracold atoms. The detection is based on resonance-enhanced multi-photon ionization. Mass resolution up to m/Δmrms=1000 at the mass of 133Cs is achieved. The performance of this spectrometer is demonstrated in the detection of photoassociated ultracold 7Li133Cs molecules near a large signal of 133Cs ions.

  8. A design for a high resolution very-low-Q time-of flight diffractometer.

    SciTech Connect

    Hjelm, R. P.

    1998-09-29

    The design of a high resolution view low-Q time of flight diffractometer was motivated by the anticipated need to perform small-angle neutron scattering measurements at far lower momentum transfer and higher precision than currently available at either pulsed or steady state sources. In addition, it was recognized that flexibility in the configuration of the instrument and ease in which data is acquired are important. The design offers two configurations, a high intensity/very low Q geometry employing a focusing mirror and a medium to high Q-precision/low Q configuration using standard pinhole collimation geometry. The quality of the mirror optics is very important to the performance of the high intensity/very low Q configuration. We believe that the necessary technology exists to fabricate the high quality mirror optics required for the instrument.

  9. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    DOEpatents

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  10. Chemical Characteristics of Particulate Matter from Vehicle emission using High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS)

    NASA Astrophysics Data System (ADS)

    Park, T.; Lee, T.; Kang, S.; Lee, J.; Kim, J.; Son, J.; Yoo, H. M.; Kim, K.; Park, G.

    2015-12-01

    Car emissions are major contributors of particulate matter (PM) in the urban environment and effects of air pollution, climate change, and human activities. By increasing of interest in research of car emission for assessment of the PM control, it became require to understand the chemical composition and characteristics of the car exhaust gases and particulate matter. To understand car emission characteristics of PM, we will study PM of car emissions for five driving modes (National Institute Environmental Research (NIER)-5, NIER-9, NIER-12, NIER-14) and three fixed speed driving modes (30km/h, 70km/h, 110km/h) using different fuel types (gasoline, diesel, and LPG) at Transportation Pollution Research Center (TPRC) of NIER in Incheon, South Korea. PM chemical composition of car emission was measured for concentrations of organics, sulfate, nitrate, ammonium, PAHs, oxidation states and size distribution using an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and engine exhaust particle sizer (EEPS) on real-time. In the study, organics concentration was dominated for all cases of driving modes and the concentration of organics was increased in 110km/h fixed speed mode for gasoline and diesel. The presentation will provide an overview of the chemical composition of PM in the car emissions.

  11. High resolution time-of-flight measurements in small and large scintillation counters

    NASA Astrophysics Data System (ADS)

    D'Agostini, G.; Marini, G.; Martellotti, G.; Massa, F.; Rambaldi, A.; Sciubba, A.

    1981-06-01

    In a test run, the experimental time-of-flight resolution was measured for several different scintillation counters of small (10 × 5 cm 2) and large (100 × 15 cm 2 and 75 × 25 cm 2) area. The design characteristics were decided on the basis of theoretical Monte Carlo calculations. We report results using twisted, fish-tail, and rectangular light-guides and different types of scintillator (NE114 and PILOT U). Time resolution up to ˜130-150 ps fwhm for the small counters and up to ˜280-300 ps fwhm for the large counters were obtained. The spatial resolution from time measurements in the large counters is also reported. The results of Monte Carlo calculations on the type of scintillator, the shape and dimensions of the light-guides, and the nature of the external wrapping surfaces — to be used in order to optimize the time resolution — are also summarized.

  12. High-resolution reflecting time-of-flight momentum and energy mapping system

    SciTech Connect

    Wang Chao; Kang Yifan; Weaver, Larry; Chang Zenghu

    2009-07-15

    A new system to map electron momentum and energy is proposed. A reflecting electrode is introduced into a time-of-flight (TOF) system whose decelerating electric field sends all the electrons back to a position-sensitive detector close to but behind the source of the electrons. The longer flying distance that results makes it possible to significantly improve the energy-resolved performance, especially in the higher energy region. The dependence of the new TOF system on its characteristic parameters is analyzed, along with its application to attosecond streak cameras. Experimental results verified a relative energy resolution better than 0.2 eV for 22 eV electrons and also revealed the availability of the improved relative energy resolution smaller than 1.0% for electron energy ranging from 30 to 40 eV.

  13. Development of high-rate MRPCs for high resolution time-of-flight systems

    NASA Astrophysics Data System (ADS)

    Wang, Jingbo; Wang, Yi; Gonzalez-Diaz, D.; Chen, Huangshan; Fan, Xingming; Li, Yuanjing; Cheng, Jianping; Kaspar, Marcus; Kotte, Roland; Laso Garcia, Alejandro; Naumann, Lothar; Stach, Daniel; Wendisch, Christian; Wüstenfeld, Jörn

    2013-06-01

    We show how the high charged-particle flux (1-20 kHz/cm2) expected over the 150 m2 large time-of-flight wall of the future Compressed Baryonic Matter experiment (CBM) at FAIR can be realistically handled with Multi-gap Resistive Plate Chambers (MRPCs). This crucial 100-fold increase of the chamber rate capability, as compared to that of standard MRPCs presently employed in experiments resorting to sub-100 ps timing, has been achieved thanks to the development of a new type of low-resistive doped glass. Following the encouraging results previously obtained with small counters, two types of modules (active area: ˜150 cm2) have been built at Tsinghua University with the new material. The measurements conveyed in this work, obtained with a quasi- minimum ionizing electron beam (γβ≥3), prove their suitability as the building blocks of the present hadron-identification concept of the CBM experiment. Namely, they provide a time resolution better than 80 ps and an efficiency above 90% at a particle flux well in excess of 20 kHz/cm2 (up to 35-60 kHz/cm2), being at the core of a modular concept that is easily scalable. Recent measurements of the electrical and mechanical properties of this new material, together with its long-term behavior, are shortly summarized.

  14. Clustering, methodology, and mechanistic insights into acetate chemical ionization using high-resolution time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Brophy, Patrick; Farmer, Delphine K.

    2016-08-01

    We present a comprehensive characterization of cluster control and transmission through the Tofwerk atmospheric pressure interface installed on various chemical ionization time-of-flight mass spectrometers using authentic standards. This characterization of the atmospheric pressure interface allows for a detailed investigation of the acetate chemical ionization mechanisms and the impact of controlling these mechanisms on sensitivity, selectivity, and mass spectral ambiguity with the aim of non-targeted analysis. Chemical ionization with acetate reagent ions is controlled by a distribution of reagent ion-neutral clusters that vary with relative humidity and the concentration of the acetic anhydride precursor. Deprotonated carboxylic acids are primarily detected only if sufficient declustering is employed inside the atmospheric pressure interface. The configuration of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) using an acetate chemical ionization source for non-targeted analysis is discussed. Recent approaches and studies characterizing acetate chemical ionization as it applies to the HR-TOF-CIMS are evaluated in light of the work presented herein.

  15. Accounting for anisotropic noise in fine registration of time-of-flight range data with high-resolution surface data.

    PubMed

    Maier-Hein, L; Schmidt, M; Franz, A M; dos Santos, T R; Seitel, A; Jähne, B; Fitzpatrick, J M; Meinzer, H P

    2010-01-01

    Time-of-Flight (ToF) sensors have become a considerable alternative to conventional surface acquisition techniques such as laser range scanning and stereo vision. Application of ToF cameras for the purpose of intra-operative registration requires matching of the noisy surfaces generated from ToF range data onto pre-interventionally acquired high-resolution surfaces. The contribution of this paper is twofold: Firstly, we present a novel method for fine rigid registration of noisy ToF data with high-resolution surface meshes taking into account both, the noise characteristics of ToF cameras and the resolution of the target mesh. Secondly, we introduce an evaluation framework for assessing the performance of ToF registration methods based on physically realistic ToF range data generated from a virtual scence. According to experiments within the presented evaluation framework, the proposed method outperforms the standard ICP algorithm with respect to correspondence search and transformation computation, leading to a decrease in the target registration error (TRE) of more than 70%.

  16. Determination of stimulants using gas chromatography/high-resolution time-of-flight mass spectrometry and a soft ionization source.

    PubMed

    Lopez-Avila, Viorica; Cooley, James; Urdahl, Randall; Thevis, Mario

    2012-12-15

    The aim of this study was to investigate the mass spectral fragmentation of a small set of stimulants in a high-resolution time-of-flight mass spectrometer equipped with a soft ionization source using vacuum ultraviolet (VUV) photons emitted from different plasma gases. It was postulated that the use of a plasma gas such as Xe, which emits photons at a lower energy than Kr or Ar, would lead to softer ionization of the test compounds, and thus to less fragmentation. A set of nine stimulants: cocaine, codeine, nicotine, methadone, phenmetrazine, pentylenetetrazole, niketamide, fencamfamine, and caffeine, was analyzed by gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) in positive ion mode with this soft ionization source, using either Xe, Kr, or Ar as plasma gases. Working solutions of the test compounds at 0.1 to 100 ng/μL were used to establish instrument sensitivity and linearity. All test compounds, except methadone and pentylenetetrazole, exhibited strong molecular ions and no fragmentation with Xe-microplasma photoionization (MPPI). Methadone exhibited significant fragmentation not only with Xe, but also with Kr and Ar, and pentylenetetrazole could not be ionized with Xe, probably because its ionization energy is above 8.44 eV. The Kr- and Ar-MPPI mass spectra of the test compounds showed that the relative intensity of the molecular ion decreased as the photon energy increased. When coupled to a TOF mass spectrometer this soft ionization source has demonstrated signal-to-noise (S/N) ratios from 7 to 730 at 100 pg per injection (depending on the compound), and a dynamic range of three orders of magnitude (100 pg to 100 ng) for some of the test compounds. Copyright © 2012 John Wiley & Sons, Ltd.

  17. A high-resolution, multi-stop, time-to-digital converter for nuclear time-of-flight measurements

    NASA Astrophysics Data System (ADS)

    Spencer, D. F.; Cole, J.; Drigert, M.; Aryaeinejad, R.

    2006-01-01

    A high-resolution, multi-stop, time-to-digital converter (TDC) was designed and developed to precisely measure the times-of-flight (TOF) of incident neutrons responsible for induced fission and capture reactions on actinide targets. The minimum time resolution is ±1 ns. The TDC design was implemented into a single, dual-wide CAMAC module. The CAMAC bus is used for command and control as well as an alternative data output. A high-speed ECL interface, compatible with LeCroy FERA modules, was also provided for the principle data output path. An Actel high-speed field programmable gate array (FPGA) chip was incorporated with an external oscillator and an internal multiple clock phasing system. This device implemented the majority of the high-speed register functions, the state machine for the FERA interface, and the high-speed counting circuit used for the TDC conversion. An external microcontroller was used to monitor and control system-level changes. In this work we discuss the performance of this TDC module as well as its application.

  18. The crystal structure of lueshite at 298 K resolved by high-resolution time-of-flight neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Kennedy, Brendan J.; Knight, Kevin S.

    2017-06-01

    Refinement of time-of-flight high-resolution neutron powder diffraction data for lueshite (Na, Ca)(Nb, Ta, Ti)O3, the natural analogue of synthetic NaNbO3, demonstrates that lueshite at room temperature (298 K) adopts an orthorhombic structure with a 2a p × 2a p × 4a p superlattice described by space group Pmmn [#59: a = 7.8032(4) Å; b = 7.8193(4) Å; c = 15.6156(9) Å]. This structure is analogous to that of phase S of synthetic NaNbO3 observed at 753-783 K (480-510 °C). In common with synthetic NaNbO3, lueshite exhibits a series of phase transitions with decreasing temperature from a cubic (Pm\\bar{3}m ) aristotype through tetragonal (P4/mbm) and orthorhombic (Cmcm) structures. However, the further sequence of phase transitions differs in that for lueshite the series terminates with the room temperature S (Pmmn) phase, and the R (Pmmn or Pnma) and P (Pbcm) phases of NaNbO3 are not observed. The appearance of the S phase in lueshite at a lower temperature, relative to that of NaNbO3, is attributable to the effects of solid solution of Ti, Ta and Ca in lueshite.

  19. Characterization of submicron aerosols during a serious pollution month in Beijing (2013) using an aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, J. K.; Sun, Y.; Liu, Z. R.; Ji, D. S.; Hu, B.; Liu, Q.; Wang, Y. S.

    2013-07-01

    In January 2013, Beijing experienced several serious haze events. To achieve a better understanding of the characteristics, sources and processes of aerosols during this month, an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed at an urban site between 1 January and 1 February 2013 to obtain the size-resolved chemical composition of non-refractory submicron particles (NR-PM1). During this period, the mean measured NR-PM1 mass concentration was 87.4 μg m-3 and was composed of organics (49.8%), sulfate (21.4%), nitrate (14.6%), ammonium (10.4%), and chloride (3.8%). Moreover, inorganic matter, such as sulfate and nitrate comprised an increasing fraction of the NR-PM1 load as NR-PM1 loading increased, denoting their key roles in particulate pollution during this month. The average size distributions of the species were all dominated by an accumulation mode peaking at approximately 600 nm in vacuum aerodynamic diameter and organics characterized by an additional smaller size (∼200 nm). Elemental analyses showed that the average O/C, H/C, and N/C (molar ratio) of organic matter were 0.34, 1.44 and 0.015, respectively, corresponding to an OM/OC ratio (mass ratio of organic matter to organic carbon) of 1.60. Positive matrix factorization (PMF) analyses of the high-resolution organic mass spectral dataset differentiated the organic aerosol into four components, i.e., oxygenated organic aerosols (OOA), cooking-related (COA), nitrogen-containing (NOA) and hydrocarbon-like (HOA), which on average accounted for 40.0, 23.4, 18.1 and 18.5% of the total organic mass, respectively. Back trajectory clustering analyses indicated that the WNW air masses were associated with the highest NR-PM1 pollution during the campaign. Aerosol particles in southern air masses were especially rich in inorganic and oxidized organic species, whereas northern air masses contained a large fraction of primary species.

  20. Quantitative chemical analysis of ambient organic aerosols using high-resolution time-of-flight aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Aiken, Allison Carol

    Atmospheric aerosols are important due to their effects on health, climate, visibility, and ecosystems. Organic aerosols (OA) comprise a large fraction of the submicron particle mass, yet their total composition, sources, and processing are not well understood. This thesis focuses on the composition and sources in order to improve the current state of knowledge on ambient OA. To analyze the composition of the total OA mass, a new elemental analysis (EA) technique for organic species (CHNO) was developed for use with the high-resolution Aerodyne Aerosol Mass Spectrometer (AMS). The method is calibrated with laboratory standards and enables fast on-line analysis (˜10 seconds) of OA from organic/inorganic mixtures. Additionally, the required sample size is reduced to ˜1 ng, approximately six orders of magnitude less than standard techniques. Elemental ratios for the total organic mass, i.e. oxygen/carbon (O/C), in addition to the organic mass to organic carbon ratio (OM/OC), are estimated with high precision (+/- 3% in the absence of air) but lower accuracy. The method is applied to both ambient and source aerosols, yielding similar results within the different OA types sampled. To characterize the sources of OA from within an urban Megacity, measurements were collected from a ground site within the Mexico City Metropolitan Area during the MILAGRO/MCMA-2006 field campaign. Standard AMS analyses, positive matrix factorization, elemental analysis, comparison with model output, and comparative analyses from different time periods, were applied to the data. The dominant OA sources identified were primary hydrocarbon-like, primary biomass burning, and secondary oxygenated OA, which were similar to source apportionment results from the chemical mass balance method using organic molecular markers. The oxygenated OA accounts for almost half of the OA on average. Biomass burning OA was heavily influenced by forest fires in the surrounding mountains, accounting for 15-23% of

  1. A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Brophy, P.; Farmer, D. K.

    2015-03-01

    A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas-phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt-1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to night time concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

  2. A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 southern oxidant and aerosol study

    NASA Astrophysics Data System (ADS)

    Brophy, P.; Farmer, D. K.

    2015-07-01

    A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt-1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to nighttime concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

  3. Assessment of a high-resolution candidate detector for prostate time-of-flight positron emission tomography.

    PubMed

    Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Garibaldi, Franco

    2012-11-01

    We report on the measurements performed using a (22)Na source on a detector element for a magnetic resonance imaging-compatible time-of-flight-positron emission tomography endorectal prostate probe, with depth-of-interaction sensitivity. It is made from a LYSO scintillator crystal, wrapped with Lumirror, readout at both ends by means of silicon photomultipliers. With a detailed description of the data analysis procedure, we show that our results point to a 400 ps coincidence resolving time and, at the same time, to a depth-of-interaction resolution of 1 mm. These appealing features, along with the tiny 1.5 mm × 1.5 mm × 10 mm crystal size, are quite promising in view of the realization of a prototype probe.

  4. Assessment of a high-resolution candidate detector for prostate time-of-flight positron emission tomography

    NASA Astrophysics Data System (ADS)

    Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Garibaldi, Franco

    2012-11-01

    We report on the measurements performed using a 22Na source on a detector element for a magnetic resonance imaging-compatible time-of-flight-positron emission tomography endorectal prostate probe, with depth-of-interaction sensitivity. It is made from a LYSO scintillator crystal, wrapped with Lumirror, readout at both ends by means of silicon photomultipliers. With a detailed description of the data analysis procedure, we show that our results point to a 400 ps coincidence resolving time and, at the same time, to a depth-of-interaction resolution of 1 mm. These appealing features, along with the tiny 1.5 mm × 1.5 mm × 10 mm crystal size, are quite promising in view of the realization of a prototype probe.

  5. Analysis of fresh Mentha haplocalyx volatile components by comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry.

    PubMed

    Cao, Gang; Shan, Qiyuan; Li, Xiaomeng; Cong, Xiaodong; Zhang, Yun; Cai, Hao; Cai, Baochang

    2011-11-21

    Fresh Mentha haplocalyx is a well known traditional Chinese medicinal material (CMM) used in both China and America. This paper reports analysis of the volatile components of fresh Mentha haplocalyx by comprehensive two-dimensional gas chromatography (GCxGC) and high-resolution time-of-flight mass spectrometry (HR-TOF-MS), a combination that provides almost complete chemical separation with elemental composition determination of analytes. 163 ketones and terpenes, including menthol and menthone, were tentatively identified, including enantiomers. This study suggests that GCxGCxHR-TOF-MS is suitable for routine identification of target compounds and enantiomers in CMM.

  6. Global characterisation of the GELINA facility for high-resolution neutron time-of-flight measurements by Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Ene, D.; Borcea, C.; Kopecky, S.; Mondelaers, W.; Negret, A.; Plompen, A. J. M.

    2010-06-01

    A comprehensive set of Monte Carlo simulations was performed with the MCNP5 code to provide a generic characterisation of the neutron and photon fluxes for time-of-flight measurements at all flight paths of the GELINA facility. Simulations were performed for the direct flux configuration (DFC, 10 keV-20 MeV) and the moderated flux configuration (MFC, 10 meV-1 MeV). Fluxes and flux energy spectra were obtained for both neutrons and photons. For neutrons, additionally, detailed resolution functions and figures of merit were obtained. The validity of the approach for the photon spectra is shown by comparison with a dedicated measurement. Also, a verification is presented of the validity of the neutron resolution function by comparison with measured capture and transmission data for 103Rh and 56Fe in the incident neutron energy range from 70 eV to 50 keV. This comprehensive overview will facilitate the planning and analysis of measurements at the GELINA facility with an improved knowledge of its physical characteristics.

  7. The Impact II, a Very High-Resolution Quadrupole Time-of-Flight Instrument (QTOF) for Deep Shotgun Proteomics.

    PubMed

    Beck, Scarlet; Michalski, Annette; Raether, Oliver; Lubeck, Markus; Kaspar, Stephanie; Goedecke, Niels; Baessmann, Carsten; Hornburg, Daniel; Meier, Florian; Paron, Igor; Kulak, Nils A; Cox, Juergen; Mann, Matthias

    2015-07-01

    Hybrid quadrupole time-of-flight (QTOF) mass spectrometry is one of the two major principles used in proteomics. Although based on simple fundamentals, it has over the last decades greatly evolved in terms of achievable resolution, mass accuracy, and dynamic range. The Bruker impact platform of QTOF instruments takes advantage of these developments and here we develop and evaluate the impact II for shotgun proteomics applications. Adaption of our heated liquid chromatography system achieved very narrow peptide elution peaks. The impact II is equipped with a new collision cell with both axial and radial ion ejection, more than doubling ion extraction at high tandem MS frequencies. The new reflectron and detector improve resolving power compared with the previous model up to 80%, i.e. to 40,000 at m/z 1222. We analyzed the ion current from the inlet capillary and found very high transmission (>80%) up to the collision cell. Simulation and measurement indicated 60% transfer into the flight tube. We adapted MaxQuant for QTOF data, improving absolute average mass deviations to better than 1.45 ppm. More than 4800 proteins can be identified in a single run of HeLa digest in a 90 min gradient. The workflow achieved high technical reproducibility (R2 > 0.99) and accurate fold change determination in spike-in experiments in complex mixtures. Using label-free quantification we rapidly quantified haploid against diploid yeast and characterized overall proteome differences in mouse cell lines originating from different tissues. Finally, after high pH reversed-phase fractionation we identified 9515 proteins in a triplicate measurement of HeLa peptide mixture and 11,257 proteins in single measurements of cerebellum-the highest proteome coverage reported with a QTOF instrument so far. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. The Impact II, a Very High-Resolution Quadrupole Time-of-Flight Instrument (QTOF) for Deep Shotgun Proteomics*

    PubMed Central

    Beck, Scarlet; Michalski, Annette; Raether, Oliver; Lubeck, Markus; Kaspar, Stephanie; Goedecke, Niels; Baessmann, Carsten; Hornburg, Daniel; Meier, Florian; Paron, Igor; Kulak, Nils A.; Cox, Juergen; Mann, Matthias

    2015-01-01

    Hybrid quadrupole time-of-flight (QTOF) mass spectrometry is one of the two major principles used in proteomics. Although based on simple fundamentals, it has over the last decades greatly evolved in terms of achievable resolution, mass accuracy, and dynamic range. The Bruker impact platform of QTOF instruments takes advantage of these developments and here we develop and evaluate the impact II for shotgun proteomics applications. Adaption of our heated liquid chromatography system achieved very narrow peptide elution peaks. The impact II is equipped with a new collision cell with both axial and radial ion ejection, more than doubling ion extraction at high tandem MS frequencies. The new reflectron and detector improve resolving power compared with the previous model up to 80%, i.e. to 40,000 at m/z 1222. We analyzed the ion current from the inlet capillary and found very high transmission (>80%) up to the collision cell. Simulation and measurement indicated 60% transfer into the flight tube. We adapted MaxQuant for QTOF data, improving absolute average mass deviations to better than 1.45 ppm. More than 4800 proteins can be identified in a single run of HeLa digest in a 90 min gradient. The workflow achieved high technical reproducibility (R2 > 0.99) and accurate fold change determination in spike-in experiments in complex mixtures. Using label-free quantification we rapidly quantified haploid against diploid yeast and characterized overall proteome differences in mouse cell lines originating from different tissues. Finally, after high pH reversed-phase fractionation we identified 9515 proteins in a triplicate measurement of HeLa peptide mixture and 11,257 proteins in single measurements of cerebellum—the highest proteome coverage reported with a QTOF instrument so far. PMID:25991688

  9. An iodide-adduct high-resolution time-of-flight chemical-ionization mass spectrometer: application to atmospheric inorganic and organic compounds.

    PubMed

    Lee, Ben H; Lopez-Hilfiker, Felipe D; Mohr, Claudia; Kurtén, Theo; Worsnop, Douglas R; Thornton, Joel A

    2014-06-03

    A high-resolution time-of-flight chemical-ionization mass spectrometer (HR-ToF-CIMS) using Iodide-adducts has been characterized and deployed in several laboratory and field studies to measure a suite of organic and inorganic atmospheric species. The large negative mass defect of Iodide, combined with soft ionization and the high mass-accuracy (<20 ppm) and mass-resolving power (R>5500) of the time-of-flight mass spectrometer, provides an additional degree of separation and allows for the determination of elemental compositions for the vast majority of detected ions. Laboratory characterization reveals Iodide-adduct ionization generally exhibits increasing sensitivity toward more polar or acidic volatile organic compounds. Simultaneous retrieval of a wide range of mass-to-charge ratios (m/Q from 25 to 625 Th) at a high frequency (>1 Hz) provides a comprehensive view of atmospheric oxidative chemistry, particularly when sampling rapidly evolving plumes from fast moving platforms like an aircraft. We present the sampling protocol, detection limits and observations from the first aircraft deployment for an instrument of this type, which took place aboard the NOAA WP-3D aircraft during the Southeast Nexus (SENEX) 2013 field campaign.

  10. Triple Quadrupole Versus High Resolution Quadrupole-Time-of-Flight Mass Spectrometry for Quantitative LC-MS/MS Analysis of 25-Hydroxyvitamin D in Human Serum.

    PubMed

    Geib, Timon; Sleno, Lekha; Hall, Rabea A; Stokes, Caroline S; Volmer, Dietrich A

    2016-08-01

    We describe a systematic comparison of high and low resolution LC-MS/MS assays for quantification of 25-hydroxyvitamin D3 in human serum. Identical sample preparation, chromatography separations, electrospray ionization sources, precursor ion selection, and ion activation were used; the two assays differed only in the implemented final mass analyzer stage; viz. high resolution quadrupole-quadrupole-time-of-flight (QqTOF) versus low resolution triple quadrupole instruments. The results were assessed against measured concentration levels from a routine clinical chemiluminescence immunoassay. Isobaric interferences prevented the simple use of TOF-MS spectra for extraction of accurate masses and necessitated the application of collision-induced dissociation on the QqTOF platform. The two mass spectrometry assays provided very similar analytical figures of merit, reflecting the lack of relevant isobaric interferences in the MS/MS domain, and were successfully applied to determine the levels of 25-hydroxyvitamin D for patients with chronic liver disease. Graphical Abstract ᅟ.

  11. Triple Quadrupole Versus High Resolution Quadrupole-Time-of-Flight Mass Spectrometry for Quantitative LC-MS/MS Analysis of 25-Hydroxyvitamin D in Human Serum

    NASA Astrophysics Data System (ADS)

    Geib, Timon; Sleno, Lekha; Hall, Rabea A.; Stokes, Caroline S.; Volmer, Dietrich A.

    2016-08-01

    We describe a systematic comparison of high and low resolution LC-MS/MS assays for quantification of 25-hydroxyvitamin D3 in human serum. Identical sample preparation, chromatography separations, electrospray ionization sources, precursor ion selection, and ion activation were used; the two assays differed only in the implemented final mass analyzer stage; viz. high resolution quadrupole-quadrupole-time-of-flight (QqTOF) versus low resolution triple quadrupole instruments. The results were assessed against measured concentration levels from a routine clinical chemiluminescence immunoassay. Isobaric interferences prevented the simple use of TOF-MS spectra for extraction of accurate masses and necessitated the application of collision-induced dissociation on the QqTOF platform. The two mass spectrometry assays provided very similar analytical figures of merit, reflecting the lack of relevant isobaric interferences in the MS/MS domain, and were successfully applied to determine the levels of 25-hydroxyvitamin D for patients with chronic liver disease.

  12. Accelerated throughput metabolic route screening in early drug discovery using high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry and automated data analysis.

    PubMed

    Mortishire-Smith, Russell J; O'Connor, Desmond; Castro-Perez, Jose M; Kirby, Jane

    2005-01-01

    The resource investment required to characterise the metabolic fate of a compound is relatively large, meaning that within a drug discovery environment relatively few compounds are characterised in depth. Rate-limiting steps include the setting up of a complex array of mass spectrometry experiments and the subsequent analysis of the large data sets produced. We describe here a strategy for the evaluation of metabolic routes using full-scan high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QToFMS) with automated data analysis using Metabolynx, a commercially available software package. Data from several structurally diverse compounds taken from the literature illustrate that, with careful setting of key parameters, this approach is able to indicate the presence of a wide range of metabolites with only a limited requirement for manual intervention. Copyright (c) 2005 John Wiley & Sons, Ltd.

  13. Characterizing a switching reagent ion chemical ionization high resolution time of flight mass spectrometer: Standard additions, External calibrations, and Inlet response during SOAS

    NASA Astrophysics Data System (ADS)

    Brophy, P.; Farmer, D.

    2013-12-01

    A high-resolution time of flight chemical ionization mass spectrometer (HRToF-CIMS) with switching reagent ion source and low pressure, gas-phase inlet was deployed during the 2013 Southern Oxidant and Aerosol Study (SOAS) in Brent, Alabama. Acetate chemistry was employed for the detection of small acids and iodine chemistry for the detection of peroxy acids. Switching between the two ion sources was found to be possible on less than ten minute time scales with minimal artifacts observed. Online calibrations for formic acid on both the acetate and iodine sources were performed every hour using both standard addition techniques as well as external standard calibrations; offline formic acid calibrations were also conducted. Inlet responses were investigated though a number of experiments finding that the inlet has minimal hysteresis and rapid response times.

  14. Rapid high-resolution spin- and angle-resolved photoemission spectroscopy with pulsed laser source and time-of-flight spectrometer

    SciTech Connect

    Gotlieb, K.; Hussain, Z.; Bostwick, A.; Jozwiak, C.; Lanzara, A.

    2013-09-15

    A high-efficiency spin- and angle-resolved photoemission spectroscopy (spin-ARPES) spectrometer is coupled with a laboratory-based laser for rapid high-resolution measurements. The spectrometer combines time-of-flight (TOF) energy measurements with low-energy exchange scattering spin polarimetry for high detection efficiencies. Samples are irradiated with fourth harmonic photons generated from a cavity-dumped Ti:sapphire laser that provides high photon flux in a narrow bandwidth, with a pulse timing structure ideally matched to the needs of the TOF spectrometer. The overall efficiency of the combined system results in near-E{sub F} spin-resolved ARPES measurements with an unprecedented combination of energy resolution and acquisition speed. This allows high-resolution spin measurements with a large number of data points spanning multiple dimensions of interest (energy, momentum, photon polarization, etc.) and thus enables experiments not otherwise possible. The system is demonstrated with spin-resolved energy and momentum mapping of the L-gap Au(111) surface states, a prototypical Rashba system. The successful integration of the spectrometer with the pulsed laser system demonstrates its potential for simultaneous spin- and time-resolved ARPES with pump-probe based measurements.

  15. Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically resolved aerosol fluxes

    NASA Astrophysics Data System (ADS)

    Farmer, D. K.; Kimmel, J. R.; Phillips, G.; Docherty, K. S.; Worsnop, D. R.; Sueper, D.; Nemitz, E.; Jimenez, J. L.

    2011-06-01

    Although laboratory studies show that biogenic volatile organic compounds (VOCs) yield substantial secondary organic aerosol (SOA), production of biogenic SOA as indicated by upward fluxes has not been conclusively observed over forests. Further, while aerosols are known to deposit to surfaces, few techniques exist to provide chemically-resolved particle deposition fluxes. To better constrain aerosol sources and sinks, we have developed a new technique to directly measure fluxes of chemically-resolved submicron aerosols using the high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) in a new, fast eddy covariance mode. This approach takes advantage of the instrument's ability to quantitatively identify both organic and inorganic components, including ammonium, sulphate and nitrate, at a temporal resolution of several Hz. The new approach has been successfully deployed over a temperate ponderosa pine plantation in California during the BEARPEX-2007 campaign, providing both total and chemically resolved non-refractory (NR) PM1 fluxes. Average deposition velocities for total NR-PM1 aerosol at noon were 2.05 ± 0.04 mm s-1. Using a high resolution measurement of the NH2+ and NH3+ fragments, we demonstrate the first eddy covariance flux measurements of particulate ammonium, which show a noon-time deposition velocity of 1.9 ± 0.7 mm s-1 and are dominated by deposition of ammonium sulphate.

  16. Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically-resolved aerosol fluxes

    NASA Astrophysics Data System (ADS)

    Farmer, D. K.; Kimmel, J. R.; Phillips, G.; Docherty, K. S.; Worsnop, D. R.; Sueper, D.; Nemitz, E.; Jimenez, J. L.

    2010-12-01

    Although laboratory studies show that biogenic volatile organic compounds (VOCs) yield substantial secondary organic aerosol (SOA), production of biogenic SOA as indicated by upward fluxes has not been conclusively observed over forests. Further, while aerosols are known to deposit to surfaces, few techniques exist to provide chemically-resolved particle deposition fluxes. To better constrain aerosol sources and sinks, we have developed a new technique to directly measure fluxes of chemically-resolved submicron aerosols using the high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) in a new, fast eddy covariance mode. This approach takes advantage of the instrument's ability to quantitatively identify both organic and inorganic components, including ammonium, sulphate and nitrate, at a temporal resolution of several Hz. The new approach has been successfully deployed over a temperate ponderosa pine plantation in California during the BEARPEX-2007 campaign, providing both total and chemically resolved non-refractory (NR) PM1 fluxes. Average deposition velocity for total NR-PM1 aerosol at noon was 2.05 ± 0.04 mm/s. Using a high resolution measurement of the NH2+ and NH3+ fragments, we demonstrate the first eddy covariance flux measurements of particulate ammonium, which show a noon-time deposition velocity of 1.9 ± 0.7 mm/s and are dominated by deposition of ammonium sulphate.

  17. [Application of gas chromatography-high resolution quadrupole time of flight mass spectrometry to the analysis of benzaldehyde, benzyl alcohol acetophenone and phenylacetaldehyde in complex aromatic samples].

    PubMed

    Liu, Junyan; Cao, Zhe; Li, Jiwen; Wang, Zheming; Wang, Chuan; Gu, Songyuan

    2015-02-01

    The study focuses on the quantitative analytical characterization of benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde in complex aromatic samples by gas chromatography-high resolution quadrupole time of flight mass spectrometry (GC-QTOF MS). The four compounds in real sample were accurately qualified and quantified through a comprehensive analysis of the GC retention times and the accurate masses of the ion fragments obtained by the high resolution MS. The new method therefore effectively avoids the interference of the real sample substrate, which reduces the accuracy of the analysis results. The peak area of the characteristic ion fragment for each compound was used for quantitation calculation. The MS signal responses of the four compounds showed good linear relationships with the corresponding mass concentrations and the linear regression coefficients were greater than 0. 99. The method recoveries were 87. 97% - 103.01%. The limits of detection (LODs) were 0. 01, 0. 03, 0. 02 and 0. 01 mg/L for benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde respectively. The contents of the four compounds in three real samples were analyzed. The study provided a new strategy for oxygenate analysis in complex aromatic samples using GC-QTOF MS. By measuring the accurate masses, the new method reduces the reliance on chromatographic separation ability and makes up the shortcomings of the traditional GC-MS methods.

  18. Application of high-resolution time-of-flight chemical ionization mass spectrometry measurements to estimate volatility distributions of α-pinene and naphthalene oxidation products

    DOE PAGES

    Chhabra, P. S.; Lambe, A. T.; Canagaratna, M. R.; ...

    2015-01-05

    Recent developments in high-resolution time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made it possible to directly detect atmospheric organic compounds in real time with high sensitivity and with little or no fragmentation, including low-volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, using ions identified by high-resolution spectra from an HR-ToF-CIMS with acetate reagent ion chemistry, we develop an algorithm to estimate the vapor pressures of measured organic acids. The algorithm uses identified ion formulas and calculated double bond equivalencies, information unavailable in quadrupole CIMS technology, as constraints for the number of possible oxygen-containing functionalmore » groups. The algorithm is tested with acetate chemical ionization mass spectrometry (acetate-CIMS) spectra of O3 and OH oxidation products of α-pinene and naphthalene formed in a flow reactor with integrated OH exposures ranged from 1.2 × 1011 to 9.7 × 1011 molec s cm−3, corresponding to approximately 1.0 to 7.5 days of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. The predicted condensed-phase secondary organic aerosol (SOA) average acid yields and O/C and H/C ratios agree within uncertainties with previous chamber and flow reactor measurements and ambient CIMS results. While acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.« less

  19. Suspected-target pesticide screening using gas chromatography-quadrupole time-of-flight mass spectrometry with high resolution deconvolution and retention index/mass spectrum library.

    PubMed

    Zhang, Fang; Wang, Haoyang; Zhang, Li; Zhang, Jing; Fan, Ruojing; Yu, Chongtian; Wang, Wenwen; Guo, Yinlong

    2014-10-01

    A strategy for suspected-target screening of pesticide residues in complicated matrices was exploited using gas chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS). The screening workflow followed three key steps of, initial detection, preliminary identification, and final confirmation. The initial detection of components in a matrix was done by a high resolution mass spectrum deconvolution; the preliminary identification of suspected pesticides was based on a special retention index/mass spectrum (RI/MS) library that contained both the first-stage mass spectra (MS(1) spectra) and retention indices; and the final confirmation was accomplished by accurate mass measurements of representative ions with their response ratios from the MS(1) spectra or representative product ions from the second-stage mass spectra (MS(2) spectra). To evaluate the applicability of the workflow in real samples, three matrices of apple, spinach, and scallion, each spiked with 165 test pesticides in a set of concentrations, were selected as the models. The results showed that the use of high-resolution TOF enabled effective extractions of spectra from noisy chromatograms, which was based on a narrow mass window (5 mDa) and suspected-target compounds identified by the similarity match of deconvoluted full mass spectra and filtering of linear RIs. On average, over 74% of pesticides at 50 ng/mL could be identified using deconvolution and the RI/MS library. Over 80% of pesticides at 5 ng/mL or lower concentrations could be confirmed in each matrix using at least two representative ions with their response ratios from the MS(1) spectra. In addition, the application of product ion spectra was capable of confirming suspected pesticides with specificity for some pesticides in complicated matrices. In conclusion, GC-QTOF MS combined with the RI/MS library seems to be one of the most efficient tools for the analysis of suspected-target pesticide residues

  20. Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Miyashita, Motoki; Suzuki, Motofumi; Kimura, Kenji

    2013-12-01

    Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

  1. Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy.

    PubMed

    Nakajima, Kaoru; Miyashita, Motoki; Suzuki, Motofumi; Kimura, Kenji

    2013-12-14

    Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

  2. Comprehensive two-dimensional liquid chromatography coupled to high resolution time of flight mass spectrometry for chemical characterization of sewage treatment plant effluents.

    PubMed

    Ouyang, Xiyu; Leonards, Pim; Legler, Juliette; van der Oost, Ron; de Boer, Jacob; Lamoree, Marja

    2015-02-06

    For the first time a comprehensive two-dimensional liquid chromatography (LC×LC) system coupled with a high resolution time-of-flight mass spectrometer (HR-ToF MS) was developed and applied for analysis of emerging toxicants in wastewater effluent. The system was optimized and validated using environmental standard compound mixtures of e.g. carbamate pesticides and polycyclic aromatic hydrocarbons (PAHs), to characterize the chromatographic system, to test the stability of the retention times and orthogonality. Various stationary phases in the second dimension were compared for the LC×LC analysis of silicon rubber passive sampler extracts of a wastewater effluent. A combination of C18 and Pentafluorophenyl (PFP) was found to be most effective. Finally, the hyphenation of LC×LC with HR-ToF MS was optimized, including splitter settings, transfer of data files between the different software packages and background subtraction using instrument software tools, after which tentative identification of 20 environmental contaminants was achieved, including pesticides, pharmaceuticals and food additives. As examples, three pesticides (isoproturon, terbutryn and diazinon) were confirmed by two-dimensional retention alignment. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Screening of environmental contaminants in honey bee wax comb using gas chromatography-high-resolution time-of-flight mass spectrometry.

    PubMed

    Gómez-Ramos, M M; García-Valcárcel, A I; Tadeo, J L; Fernández-Alba, A R; Hernando, M D

    2016-03-01

    This study reports an analytical approach intended to be used for investigation of non-targeted environmental contaminants and to characterize the organic pollution pattern of bee wax comb samples. The method comprises a generic extraction followed by detection with gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF-MS), operated in electron impact ionization (EI) mode. The screening approach for the investigation of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS(1) with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, the molecular formula of representative ions (molecular ion when present in the EI spectrum) and, for at least other two fragment ions, was provided for those with an accurate mass scoring (mass error < 5 ppm). This methodology was applied for screening environmental contaminants in 50 samples of bee wax comb. This approach has allowed the tentative identification of some GC-amenable contaminants belonging to different chemical groups, among them, phthalates and polycyclic aromatic hydrocarbons (PAHs), along with residues of veterinary treatments used in apiculture.

  4. Performance characterization of high quantum efficiency metal package photomultiplier tubes for time-of-flight and high-resolution PET applications

    SciTech Connect

    Ko, Guen Bae; Lee, Jae Sung

    2015-01-15

    Purpose: Metal package photomultiplier tubes (PMTs) with a metal channel dynode structure have several advanced features for devising such time-of-flight (TOF) and high spatial resolution positron emission tomography (PET) detectors, thanks to their high packing density, large effective area ratio, fast time response, and position encoding capability. Here, we report on an investigation of new metal package PMTs with high quantum efficiency (QE) for high-resolution PET and TOF PET detector modules. Methods: The latest metal package PMT, the Hamamatsu R11265 series, is served with two kinds of photocathodes that have higher quantum efficiency than normal bialkali (typical QE ≈ 25%), super bialkali (SBA; QE ≈ 35%), and ultra bialkali (UBA; QE ≈ 43%). In this study, the authors evaluated the performance of the new PMTs with SBA and UBA photocathodes as a PET detector by coupling various crystal arrays. They also investigated the performance improvements of high QE, focusing in particular on a block detector coupled with a lutetium-based scintillator. A single 4 × 4 × 10 mm{sup 3} LYSO, a 7 × 7 array of 3 × 3 × 20 mm{sup 3} LGSO, a 9 × 9 array of 1.2 × 1.2 × 10 mm{sup 3} LYSO, and a 6 × 6 array of 1.5 × 1.5 × 7 mm{sup 3} LuYAP were used for evaluation. All coincidence data were acquired with a DRS4 based fast digitizer. Results: This new PMT shows promising crystal positioning accuracy, energy and time discrimination performance for TOF, and high-resolution PET applications. The authors also found that a metal channel PMT with SBA was enough for both TOF and high-resolution application, although UBA gave a minor improvement to time resolution. However, significant performance improvement was observed in relative low light output crystals (LuYAP) coupled with UBA. Conclusions: The results of this study will be of value as a useful reference to select PMTs for high-performance PET detectors.

  5. Development of a new corona discharge based ion source for high resolution time-of-flight chemical ionization mass spectrometer to measure gaseous H2SO4 and aerosol sulfate

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Yang, Dongsen; Ma, Yan; Chen, Mindong; Cheng, Jin; Li, Shizheng; Wang, Ming

    2015-10-01

    A new corona discharge (CD) based ion source was developed for a commercial high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) (Aerodyne Research Inc.) to measure both gaseous sulfuric acid (H2SO4) and aerosol sulfate after thermal desorption. Nitrate core ions (NO3-) were used as reagent ions and were generated by a negative discharge in zero air followed by addition of excess nitrogen dioxide (NO2) to convert primary ions and hydroxyl radicals (OH) into NO3- ions and nitric acid (HNO3). The CD-HRToF-CIMS showed no detectable interference from hundreds parts per billion by volume (ppbv) of sulfur dioxide (SO2). Unlike the atmospheric pressure ionization (API) ToF-CIMS, the CD ion source was integrated onto the ion-molecule reaction (IMR) chamber and which made it possible to measure aerosol sulfate by coupling to a filter inlet for gases and aerosols (FIGAERO). Moreover, compared with a quadrupole-based mass spectrometer, the desired HSO4- signal was detected by its exact mass of m/z 96.960, which was well resolved from the potential interferences of HCO3-ṡ(H2O)2 (m/z 97.014) and O-ṡH2OṡHNO3 (m/z 97.002). In this work, using laboratory-generated standards the CD-HRToF-CIMS was demonstrated to be able to detect as low as 3.1 × 105 molecules cm-3 gaseous H2SO4 and 0.5 μg m-3 ammonium sulfate based on 10-s integration time and two times of the baseline noise. The CD ion source had the advantages of low cost and a simple but robust structure. Since the system was non-radioactive and did not require corrosive HNO3 gas, it can be readily field deployed. The CD-HRToF-CIMS can be a powerful tool for both field and laboratory studies of aerosol formation mechanism and the chemical processes that were critical to understand the evolution of aerosols in the atmosphere.

  6. A two stage algorithm for target and suspect analysis of produced water via gas chromatography coupled with high resolution time of flight mass spectrometry.

    PubMed

    Samanipour, Saer; Langford, Katherine; Reid, Malcolm J; Thomas, Kevin V

    2016-09-09

    Gas chromatography coupled with high resolution time of flight mass spectrometry (GC-HR-TOFMS) has gained popularity for the target and suspect analysis of complex samples. However, confident detection of target/suspect analytes in complex samples, such as produced water, remains a challenging task. Here we report on the development and validation of a two stage algorithm for the confident target and suspect analysis of produced water extracts. We performed both target and suspect analysis for 48 standards, which were a mixture of 28 aliphatic hydrocarbons and 20 alkylated phenols, in 3 produced water extracts. The two stage algorithm produces a chemical standard database of spectra, in the first stage, which is used for target and suspect analysis during the second stage. The first stage is carried out through five steps via an algorithm here referred to as unique ion extractor (UIE). During the first step the m/z values in the spectrum of a standard that do not belong to that standard are removed in order to produce a clean spectrum and then during the last step the cleaned spectrum is calibrated. The Dot-product algorithm, during the second stage, uses the cleaned and calibrated spectra of the standards for both target and suspect analysis. We performed the target analysis of 48 standards in all 3 samples via conventional methods, in order to validate the two stage algorithm. The two stage algorithm was demonstrated to be more robust, reliable, and less sensitive to the signal-to-noise ratio (S/N), when compared to the conventional method. The Dot-product algorithm showed lower potential in producing false positives compared to the conventional methods, when dealing with complex samples. We also evaluated the effect of the mass accuracy on the performances of Dot-product algorithm. Our results indicated the crucial importance of HR-MS data and the mass accuracy for confident suspect analysis in complex samples.

  7. Laboratory and Ambient Measurements of Oxidized Organic Compounds in the Gas Phase Using Nitrate Ion Chemical Ionization Coupled with High Resolution Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Stark, H.; Canagaratna, M. R.; Krechmer, J.; Lambe, A. T.; Isaacman-VanWertz, G. A.; Nowak, J. B.; Kimmel, J.; Kroll, J. H.; Jayne, J. T.; Worsnop, D. R.

    2015-12-01

    Chemical Ionization Mass Spectrometry (CIMS) is a widely used technique for molecular level characterization of inorganic and organic gas phase species. Here we present laboratory and ambient measurements of gaseous organic compounds by means of a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometry (HR-ToF-CIMS) using nitrate ion (NO3-) chemistry, which recently has proven capable of selectively detecting oxidized organic molecules in the gas-phase via clustering with NO3- and its high order clusters. Such low and extremely low volatility organic compounds (LVOC, ELVOC) have an important role in particulate phase chemistry and formation of secondary organic aerosol (SOA). The HR-ToF-CIMS was deployed during the Southern Oxidant and Aerosol Study (SOAS) at the forest site in Centreville, AL (June 1 - July 15, 2013), where emissions were dominated by biogenic volatile organic compounds (BVOC), occasionally mixing with anthropogenic emissions. During SOAS, the HR-ToF-CIMS detected oxidation products of both isoprene (typically C5 LVOC) and terpenes (typically C10 ELVOC). The isoprene-related LVOC showed a diurnal cycle with a day time peak, while two groups of terpene ELVOC were identified, one peaking at night and one peaking during the day. Positive Matrix Factorization (PMF) analyses are applied to the dataset to further interpret these observations. The effect of anthropogenic pollution on the biogenic-dominated environment was also investigated during periods of elevated nitrous and sulfur dioxide levels. To further aid in interpretation of the SOAS dataset, oxidized organic molecules were produced via OH and O3 initiated oxidation of biogenic gas-phase precursors in targeted laboratory studies and detected using the HR-ToF-CIMS. Spectra were obtained in these studies over a range of simulated atmospheric conditions.

  8. Measurements of Oxidized Organic Compounds during SOAS 2013 using nitrate ion chemical ionization coupled with High Resolution Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Stark, H.; Cnagaratna, M.; Junninen, H.; Hakala, J. P.; Mauldin, R.; Ehn, M.; Sipila, M.; Krechmer, J.; Kimmel, J.; Jimenez, J. L.; Jayne, J. T.; Worsnop, D. R.

    2013-12-01

    We present ambient measurements of gaseous organic compounds by means of a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometry (HR-ToF-CIMS) using nitrate ion (NO3-) chemistry. This technique allows to selectively detect oxidized gas-phase species, e.g., oxidized organic molecules and sulfuric acid via clustering with NO3- and its high order clusters. The capability of making such measurements is important because both sulfuric acid and organic gas molecules have a recognized key role in new particle formation (NPF) processes and likely have an important role in particulate phase chemistry and formation of secondary organic aerosols (SOA). The HR-ToF-CIMS was deployed during the Southern Oxidant and Aerosol Study (SOAS) at the forest supersite in Centreville, AL, from June 1 to July 15, 2013. The main goal of the SOAS campaign was to investigate the composition and sources of SOA in the Southeast US, where emissions are mainly represented by biogenic volatile organic compounds (BVOC) emissions and in less extent by anthropogenic emissions (AVOC). During SOAS, the HR-ToF-CIMS detected a range of organic ions that based on previous literature could be identified as oxidation products of both isoprene and terpenes. The isoprene products were 5 to 10 times more abundant than the terpene products. The isoprene-related molecules showed a diurnal cycle with a day time peak, typically after 1500 local time, while the terpene products were higher at night (between 2000 and 0600 local time). These results are consistent with the diurnal trends of primary BVOC emissions from other co-located instruments. The ambient data are also compared to laboratory measurements where oxidized organic vapors are produced using a Potential Aerosol Mass (PAM) flow reactor by the OH oxidation of biogenic gas-phase precursors (isoprene, a-pinene) over multiple days of equivalent atmospheric exposure.

  9. Heterogeneous oxidation products of branched and linear unsaturated hydrocarbons as characterized by two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Nah, T.; Zhang, H.; Worton, D. R.; Ruehl, C. R.; Goldstein, A. H.; Leone, S. R.; Wilson, K. R.

    2013-12-01

    Previous research has shown that molecular structure (e.g. degree of branching) can influence reaction rates and mechanisms in heterogeneous hydrocarbon oxidation. In this study, we provide new insights into the influence of molecular structure on product formation chemistry in the OH-initiated oxidation of unsaturated hydrocarbon aerosols. Submicron aerosol particles composed of either squalene (branched alkene) or linolenic acid (linear unsaturated fatty acid) were oxidized by OH radicals in the presence and absence of oxygen in a photochemical flow reactor. Oxidation products are collected on filters and analyzed using two-dimensional gas chromatography, with high-resolution time-of-flight mass spectrometric detection utilizing vacuum ultraviolet photoionization and electron impact ionization. The oxidation products were separated, identified, and quantified. We observed that in the absence of oxygen, the OH oxidation of squalene aerosol mainly leads to the formation of functionalization products with one alcohol functional group. These functionalization products are found to be a result of intermolecular hydrogen atom abstraction by the hydroxyalkyl radical (i.e. chain propagation) and are consistent with previously measured squalene effective uptake coefficients that are observed to be larger than one. Reaction pathways that cleave C-C bonds are observed to be strongly suppressed when oxygen is absent, but become more prevalent when oxygen is present in the oxidation of squalene aerosol. In contrast, the presence of oxygen generally does not influence the formation of functionalization and fragmentation products in the OH oxidation of linolenic acid aerosols. These results provide new molecular and mechanistic insights into the reaction pathways in the OH-initiated oxidation of branched and linear unsaturated hydrocarbon aerosols.

  10. High-resolution Rydberg tagging time-of-flight measurements of atomic photofragments by single-photon vacuum ultraviolet laser excitation

    SciTech Connect

    Jones, Brant; Zhou Jingang; Yang Lei; Ng, C. Y.

    2008-12-15

    By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF measurements of O({sup 3}P{sub 2}) and S({sup 3}P{sub 2}) formed in the photodissociation of SO{sub 2} and CS{sub 2} at 193.3 and 202.3 nm, respectively. These results are compared to those obtained by employing the VUV laser photoionization time-sliced velocity-mapped ion imaging technique. The fact that the kinetic energy resolutions achieved in the VUV laser high-n Rydberg tagging TOF measurements of O and S atoms are found to be higher than those observed in the VUV laser photoionization, time-sliced velocity-mapped ion imaging studies show that the single-photon VUV laser high-n Rydberg tagging TOF method is useful and complementary to state-of-the-art time-sliced velocity-mapped ion imaging measurements of heavier atomic photofragments, such as O and S atoms. Furthermore, the general agreement observed between the VUV laser high-n Rydberg tagging TOF and velocity-mapped ion imaging experiments supports the conclusion that the lifetimes of the tagged Rydberg states of O and S atoms are sufficiently long to allow the reliable determination of state-resolved UV photodissociation cross sections of SO{sub 2} and CS{sub 2} by using the VUV laser high-n Rydberg tagging TOF method.

  11. Comparison between drug screening by immunoassay and ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry in post-mortem urine.

    PubMed

    Sundström, Mira; Pelander, Anna; Ojanperä, Ilkka

    2015-05-01

    Immunoassay is currently the most common approach for urine drug screening. However, the continuous emergence of new psychoactive substances (NPS) and their low urinary concentrations have challenged the scope and sensitivity of immunoassays. Consequently, specialized toxicology laboratories rely more and more on mass spectrometry (MS) based techniques. Ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOF-MS) is an especially attractive technique for comprehensive drug screening. The objective was to compare the performances of immunoassay and UHPLC-HR-TOF-MS in terms of scope, flexibility, sensitivity, and reliability of substance identification. A total of 279 post-mortem urine samples were analyzed using a method representative of each technique. The immunoassay method was an Emit II Plus enzyme immunoassay for the following drug groups: amphetamines, benzodiazepines, buprenorphine, cannabis, and opiates. The UHPLC-HR-TOF-MS method was a recently published method covering hundreds of drugs: conventional drugs of abuse, abused prescription drugs, and NPS of various classes. UHPLC-HR-TOF-MS produced a lower number of false positive (FP) results for the drug groups covered by immunoassay. Many of the false negative (FN, n = 40) and FP (n = 22) immunoassay results were obviously due to the higher cut-off concentrations and interfering matrix, respectively. Moreover, the wider scope of UHPLC-HR-TOF-MS allowed detection of NPS and prescription drugs. UHPLC-HR-TOF-MS gave FP results related to a few particular substances. The future option of adjusting all compound-specific reporting parameters individually would allow the method's sensitivity and specificity to be fully exploited.

  12. Characterization of biomass burning emissions from cooking fires, peat, crop residue, and other fuels with high-resolution proton-transfer-reaction time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Stockwell, C. E.; Veres, P. R.; Williams, J.; Yokelson, R. J.

    2015-01-01

    We deployed a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) to measure biomass-burning emissions from peat, crop residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experiment (FLAME-4) laboratory campaign. A combination of gas standard calibrations and composition sensitive, mass-dependent calibration curves was applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign the best identities to most major "exact masses", including many high molecular mass species. Using these methods, approximately 80-96% of the total NMOC mass detected by the PTR-TOF-MS and Fourier transform infrared (FTIR) spectroscopy was positively or tentatively identified for major fuel types. We report data for many rarely measured or previously unmeasured emissions in several compound classes including aromatic hydrocarbons, phenolic compounds, and furans; many of these are suspected secondary organic aerosol precursors. A large set of new emission factors (EFs) for a range of globally significant biomass fuels is presented. Measurements show that oxygenated NMOCs accounted for the largest fraction of emissions of all compound classes. In a brief study of various traditional and advanced cooking methods, the EFs for these emissions groups were greatest for open three-stone cooking in comparison to their more advanced counterparts. Several little-studied nitrogen-containing organic compounds were detected from many fuel types, that together accounted for 0.1-8.7% of the fuel nitrogen, and some may play a role in new particle formation.

  13. In-Flight Chemical Composition Observations of Aircraft Emissions using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2015-12-01

    Commercial aircraft are an important source of aerosols to the upper troposphere. The microphysical and chemical properties of these emitted aerosols govern their ability to act as ice nuclei, both in near-field contrails and for cirrus formation downstream. During the ACCESS-II (Alternative Fuel Effects on Contrails and Cruise Emissions) campaign, NASA DC-8 CFM56-2-C1 engine emissions were sampled systematically at a range of cruise-relevant thrust levels and at several altitudes. Sampling was done aboard the NASA HU-25 Falcon aircraft, which was equipped with a suite of aerosol and gas-phase instruments focused on assessing the effects of burning different fuel mixtures on aerosol properties and their associated contrails. Here we present in-flight measurements of particle chemical composition made by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The AMS was able to sufficiently resolve near-field (within 100m) aircraft emissions plumes. Low-sulfur HEFA (hydro-processed esters and fatty-acids) and JetA fuels yielded particles that contained 11 and 8% sulfate, respectively, compared to 30% sulfate contribution for traditional JetA fuel. Each of the fuels produced organic aerosol with similarly low oxygen content. Lubrication oils, which are not a combustion product but result from leaks in the engine, were likely a dominant fraction of the measured organic mass based on mass-spectral marker analysis. These results are compared to similar engine conditions from ground-based testing.

  14. Rapid analysis of multiple pesticide residues in fruit-based baby food using programmed temperature vaporiser injection–low pressure gas chromatography–high-resolution time-of-flight mass spectrometry

    USDA-ARS?s Scientific Manuscript database

    A rapid method using programmed temperature vaporizer injection–low-pressure gas chromatography–high-resolution time-of-flight mass spectrometry (PTV–LP-GC–HRTOFMS) for the analysis of multiple pesticide residues in fruit-based baby food was developed. The fast and inexpensive buffered QuEChERS ext...

  15. Multi-residue screening of veterinary drugs in egg, fish and meat using high-resolution liquid chromatography accurate mass time-of-flight mass spectrometry.

    PubMed

    Peters, R J B; Bolck, Y J C; Rutgers, P; Stolker, A A M; Nielen, M W F

    2009-11-13

    The last 2 years multi-compound methods are gaining ground as screening methods. In this study a high-resolution liquid chromatography combined with time-of-flight mass spectrometry (HRLC-ToF-MS) is tested for the screening of about 100 veterinary drugs in three matrices, meat, fish and egg. While the results are satisfactory for 70-90% of the veterinary drugs, a more efficient sample preparation or extract purification is required for quantitative analysis of all analytes in more difficult matrices like egg. The average mass measurement error of the ToF-MS for the veterinary drugs spiked at concentrations ranging from 4 to 400 microg/kg, is 3.0 ppm (median 2.5 ppm) with little difference between the three matrices, but slightly decreases with increasing concentration. The SigmaFit value, a new feature for isotope pattern matching, also decreases with increasing concentration and, in addition, shows an increase with increasing matrix complexity. While the average SigmaFit value is 0.04, the median is 0.01 indicating some high individual deviations. As with the mass measurement error, the highest deviations are found in those regions of the chromatogram where most compounds elute from the column, be it analytes or matrix compounds. The median repeatability of the method ranges from 8% to 15%, decreasing with increasing concentration, while the median reproducibility ranges from 15% to 20% with little difference between matrices and concentrations. The median accuracy is in between 70% and 100% with a few compounds showing higher values due to matrix interference. The squared regression coefficient is >0.99 for 92% of the compounds showing a good overall linearity for most compounds. The detection capability, CCbeta, is within 2 times the associated validation level for >90% of the compounds studied. By changing a few conditions in the analyses protocol and analysing a number of blank samples, it was determined that the method is robust as well as specific. Finally

  16. Detection of atmospheric gaseous amines and amides by a high-resolution time-of-flight chemical ionization mass spectrometer with protonated ethanol reagent ions

    NASA Astrophysics Data System (ADS)

    Yao, Lei; Wang, Ming-Yi; Wang, Xin-Ke; Liu, Yi-Jun; Chen, Hang-Fei; Zheng, Jun; Nie, Wei; Ding, Ai-Jun; Geng, Fu-Hai; Wang, Dong-Fang; Chen, Jian-Min; Worsnop, Douglas R.; Wang, Lin

    2016-11-01

    Amines and amides are important atmospheric organic-nitrogen compounds but high time resolution, highly sensitive, and simultaneous ambient measurements of these species are rather sparse. Here, we present the development of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) method, utilizing protonated ethanol as reagent ions to simultaneously detect atmospheric gaseous amines (C1 to C6) and amides (C1 to C6). This method possesses sensitivities of 5.6-19.4 Hz pptv-1 for amines and 3.8-38.0 Hz pptv-1 for amides under total reagent ion signals of ˜ 0.32 MHz. Meanwhile, the detection limits were 0.10-0.50 pptv for amines and 0.29-1.95 pptv for amides at 3σ of the background signal for a 1 min integration time. Controlled characterization in the laboratory indicates that relative humidity has significant influences on the detection of amines and amides, whereas the presence of organics has no obvious effects. Ambient measurements of amines and amides utilizing this method were conducted from 25 July to 25 August 2015 in urban Shanghai, China. While the concentrations of amines ranged from a few parts per trillion by volume to hundreds of parts per trillion by volume, concentrations of amides varied from tens of parts per trillion by volume to a few parts per billion by volume. Among the C1- to C6-amines, the C2-amines were the dominant species with concentrations up to 130 pptv. For amides, the C3-amides (up to 8.7 ppb) were the most abundant species. The diurnal and backward trajectory analysis profiles of amides suggest that in addition to the secondary formation of amides in the atmosphere, industrial emissions could be important sources of amides in urban Shanghai. During the campaign, photo-oxidation of amines and amides might be a main loss pathway for them in daytime, and wet deposition was also an important sink.

  17. Characterization of the sources and processes of organic and inorganic aerosols in New York City with a high-resolution time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Sun, Y.-L.; Zhang, Q.; Schwab, J. J.; Demerjian, K. L.; Chen, W.-N.; Bae, M.-S.; Hung, H.-M.; Hogrefe, O.; Frank, B.; Rattigan, O. V.; Lin, Y.-C.

    2010-10-01

    Submicron aerosol particles (PM1) were measured in-situ using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during the summer 2009 Field Intensive Study at Queens College in New York City. Organic aerosol (OA) and sulfate are the two dominant species, accounting for 54% and 24%, respectively, of total PM1 mass on average. The average mass size distribution of OA presents a small mode peaking at ~150 nm (Dva) in addition to an accumulation mode (~550 nm) that is internally mixed with sulfate, nitrate, and ammonium. The diurnal cycles of sulfate and OA both show pronounced peaks between 01:00-02:00 p.m. EST due to photochemical production. The average (±1σ) oxygen-to-carbon (O/C), hydrogen-to-carbon (H/C), and nitrogen-to-carbon (N/C) ratios of OA in NYC are 0.36 (±0.09), 1.49 (±0.08), and 0.012(±0.005), respectively, corresponding to an average organic mass-to-carbon (OM/OC) ratio of 1.62(±0.11). Positive matrix factorization (PMF) of the high resolution mass spectra identified five OA components: a hydrocarbon-like OA (HOA), two types of oxygenated OA (OOA) including a low-volatility OOA (LV-OOA) and a semi-volatile OOA (SV-OOA), a cooking-emission related OA (COA), and a unique nitrogen-enriched OA (NOA). HOA appears to represent primary OA (POA) from urban traffic emissions. It comprises primarily of reduced species (H/C=1.83; O/C=0.06) and shows a mass spectral pattern very similar to those of POA from fossil fuel combustion, and correlates tightly with traffic emission tracers including elemental carbon and NOx. LV-OOA, which is highly oxidized (O/C=0.63) and correlates well with sulfate, appears to be representative for regional, aged secondary OA (SOA). SV-OOA, which is less oxidized (O/C=0.38) and correlates well with non-refractory chloride, likely represents less photo-chemically aged, semi-volatile SOA. COA shows a similar spectral pattern to the reference spectra of POA from cooking emissions and a distinct diurnal pattern

  18. Characterization of the sources and processes of organic and inorganic aerosols in New York city with a high-resolution time-of-flight aerosol mass apectrometer

    NASA Astrophysics Data System (ADS)

    Sun, Y.-L.; Zhang, Q.; Schwab, J. J.; Demerjian, K. L.; Chen, W.-N.; Bae, M.-S.; Hung, H.-M.; Hogrefe, O.; Frank, B.; Rattigan, O. V.; Lin, Y.-C.

    2011-02-01

    Submicron aerosol particles (PM1) were measured in-situ using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer during the summer 2009 Field Intensive Study at Queens College in New York, NY. Organic aerosol (OA) and sulfate are the two dominant species, accounting for 54% and 24%, respectively, of the total PM1 mass. The average mass-based size distribution of OA presents a small mode peaking at ~150 nm (Dva) and an accumulation mode (~550 nm) that is internally mixed with sulfate, nitrate, and ammonium. The diurnal cycles of both sulfate and OA peak between 01:00-02:00 p.m. EST due to photochemical production. The average (±σ) oxygen-to-carbon (O/C), hydrogen-to-carbon (H/C), and nitrogen-to-carbon (N/C) ratios of OA in NYC are 0.36 (±0.09), 1.49 (±0.08), and 0.012 (±0.005), respectively, corresponding to an average organic mass-to-carbon (OM/OC) ratio of 1.62 (±0.11). Positive matrix factorization (PMF) of the high resolution mass spectra identified two primary OA (POA) sources, traffic and cooking, and three secondary OA (SOA) components including a highly oxidized, regional low-volatility oxygenated OA (LV-OOA; O/C = 0.63), a less oxidized, semi-volatile SV-OOA (O/C = 0.38) and a unique nitrogen-enriched OA (NOA; N/C = 0.053) characterized with prominent CxH2x + 2N+ peaks likely from amino compounds. Our results indicate that cooking and traffic are two distinct and mass-equivalent POA sources in NYC, together contributing ~30% of the total OA mass during this study. The OA composition is dominated by secondary species, especially during high PM events. SV-OOA and LV-OOA on average account for 34% and 30%, respectively, of the total OA mass. The chemical evolution of SOA in NYC appears to progress with a continuous oxidation from SV-OOA to LV-OOA, which is further supported by a gradual increase of O/C ratio and a simultaneous decrease of H/C ratio in total OOA. Detailed analysis of NOA (5.8% of OA) presents evidence that organic nitrogen

  19. An experimental setup for high resolution 10.5 eV laser-based angle-resolved photoelectron spectroscopy using a time-of-flight electron analyzer.

    PubMed

    Berntsen, M H; Götberg, O; Tjernberg, O

    2011-09-01

    We present an experimental setup for laser-based angle-resolved time-of-flight photoemission. Using a picosecond pulsed laser, photons of energy 10.5 eV are generated through higher harmonic generation in xenon. The high repetition rate of the light source, variable between 0.2 and 8 MHz, enables high photoelectron count rates and short acquisition times. By using a time-of-flight analyzer with angle-resolving capabilities, electrons emitted from the sample within a circular cone of up to ±15° can be collected. Hence, simultaneous acquisition of photoemission data for a complete area of the Brillouin zone is possible. The current photon energy enables bulk sensitive measurements, high angular resolution, and the resulting covered momentum space is large enough to enclose the entire Brillouin zone in cuprate high-T(c) superconductors. Fermi edge measurements on polycrystalline Au shows an energy resolution better than 5 meV. Data from a test measurement of the Au(111) surface state are presented along with measurements of the Fermi surface of the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8 + δ) (Bi2212).

  20. High-resolution time-of-flight mass spectrometry fingerprinting of metabolites from cecum and distal colon contents of rats fed resistant starch

    SciTech Connect

    Anderson, Timothy J.; Jones, Roger W.; Ai, Yongfeng; Houk, Robert S.; Jane, Jay-lin; Zhao, Yinsheng; Birt, Diane F.; McClelland, John F.

    2013-12-04

    Time-of-flight mass spectrometry along with statistical analysis was utilized to study metabolic profiles among rats fed resistant starch (RS) diets. Fischer 344 rats were fed four starch diets consisting of 55 % (w/w, dbs) starch. A control starch diet consisting of corn starch was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. A subgroup received antibiotic treatment to determine if perturbations in the gut microbiome were long lasting. A second subgroup was treated with azoxymethane (AOM), a carcinogen. At the end of the 8-week study, cecal and distal colon content samples were collected from the sacrificed rats. Metabolites were extracted from cecal and distal colon samples into acetonitrile. The extracts were then analyzed on an accurate-mass time-of-flight mass spectrometer to obtain their metabolic profile. The data were analyzed using partial least-squares discriminant analysis (PLS-DA). The PLS-DA analysis utilized a training set and verification set to classify samples within diet and treatment groups. PLS-DA could reliably differentiate the diet treatments for both cecal and distal colon samples. The PLS-DA analyses of the antibiotic and no antibiotic-treated subgroups were well classified for cecal samples and modestly separated for distal colon samples. PLS-DA analysis had limited success separating distal colon samples for rats given AOM from those not treated; the cecal samples from AOM had very poor classification. Mass spectrometry profiling coupled with PLS-DA can readily classify metabolite differences among rats given RS diets.

  1. High-resolution time-of-flight mass spectrometry fingerprinting of metabolites from cecum and distal colon contents of rats fed resistant starch.

    PubMed

    Anderson, Timothy J; Jones, Roger W; Ai, Yongfeng; Houk, Robert S; Jane, Jay-lin; Zhao, Yinsheng; Birt, Diane F; McClelland, John F

    2014-01-01

    Time-of-flight mass spectrometry along with statistical analysis was utilized to study metabolic profiles among rats fed resistant starch (RS) diets. Fischer 344 rats were fed four starch diets consisting of 55 % (w/w, dbs) starch. A control starch diet consisting of corn starch was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. A subgroup received antibiotic treatment to determine if perturbations in the gut microbiome were long lasting. A second subgroup was treated with azoxymethane (AOM), a carcinogen. At the end of the 8-week study, cecal and distal colon content samples were collected from the sacrificed rats. Metabolites were extracted from cecal and distal colon samples into acetonitrile. The extracts were then analyzed on an accurate-mass time-of-flight mass spectrometer to obtain their metabolic profile. The data were analyzed using partial least-squares discriminant analysis (PLS-DA). The PLS-DA analysis utilized a training set and verification set to classify samples within diet and treatment groups. PLS-DA could reliably differentiate the diet treatments for both cecal and distal colon samples. The PLS-DA analyses of the antibiotic and no antibiotic-treated subgroups were well classified for cecal samples and modestly separated for distal colon samples. PLS-DA analysis had limited success separating distal colon samples for rats given AOM from those not treated; the cecal samples from AOM had very poor classification. Mass spectrometry profiling coupled with PLS-DA can readily classify metabolite differences among rats given RS diets.

  2. Analysis of selected designer benzodiazepines by UHPLC with high-resolution time-of-flight mass spectrometry and the estimation of their partition coefficients by micellar electrokinetic chromatography.

    PubMed

    Tomková, Jana; Švidrnoch, Martin; Maier, Vítězslav; Ondra, Peter

    2017-03-07

    A new ultra high performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry method for the selective and sensitive separation, identification and determination of selected designer benzodiazepines (namely, pyrazolam, phenazepam, etizolam, flubromazepam, diclazepam, deschloroetizolam, bentazepam, nimetazepam and flubromazolam) in human serum was developed. The separation of the studied designer benzodiazepines was achieved on C18 chromatographic column using gradient elution within 6 min without any significant matrix interferences. Liquid-liquid extraction with butyl acetate was applied for serum samples clean-up and preconcentration of studied designer benzodiazepines. The method was validated in terms of linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability. The limit of detection values were in range 0.10-0.15 ng/mL. The method was applied on spiked serum sample to demonstrate its applicability for systematic toxicology analysis. Furthermore, a capillary chromatographic method with micellar electrokinetic chromatography was used for the estimation of partition coefficients of studied designer benzodiazepines as important parameters to evaluate their pharmacological and toxicological properties. This article is protected by copyright. All rights reserved.

  3. Performance of the extreme ultraviolet high resolution undulator beamline BW3 at Hasylab: First results and time-of-flight spectroscopy

    NASA Astrophysics Data System (ADS)

    Björneholm, O.; Federmann, F.; Larsson, C.; Hahn, U.; Rieck, A.; Kakar, S.; Möller, T.; Beutler, A.; Fössing, F.

    1995-02-01

    The extreme ultraviolet beamline BW3 at Hasylab is a state of the art beamline for the energy range 15-2000 eV consisting of a triple undulator equipped with a modified high-flux SX-700 plane grating monochromator. The first three optical elements of the beamline are made of graphite coated with SiC to withstand the high heat load at the 4.5 GeV storage ring Doris III. Excellent spectral resolution of the order of 104 at the nitrogen K edge at 400 eV is obtained by replacing the elliptical focusing mirror of the original SX-700 design by a spherical mirror with very small tangent errors and with a large focal length in order to suppress spherical aberrations. In the energy range 50-1700 eV a photon flux of 1011-1013/s is obtained in a bandpass of 0.1%. Photoionization and photoemission measurements on atoms, molecules, and clusters making use of time-of-flight techniques demonstrate the excellent performance of the beamline.

  4. Accurate mass determination, quantification and determination of detection limits in liquid chromatography-high-resolution time-of-flight mass spectrometry: challenges and practical solutions.

    PubMed

    Vergeynst, Leendert; Van Langenhove, Herman; Joos, Pieter; Demeestere, Kristof

    2013-07-30

    Uniform guidelines for the data processing and validation of qualitative and quantitative multi-residue analysis using full-spectrum high-resolution mass spectrometry are scarce. Through systematic research, optimal mass accuracy and sensitivity are obtained after refining the post-processing of the HRMS data. For qualitative analysis, transforming the raw profile spectra to centroid spectra is recommended resulting in a 2.3 fold improved precision on the accurate mass determination of spectrum peaks. However, processing centroid data for quantitative purposes could lead to signal interruption when too narrow mass windows are applied for the construction of extracted ion chromatograms. Therefore, peak integration on the raw profile data is recommended. An optimal width of the mass window of 50 ppm, which is a trade-off between sensitivity and selectivity, was obtained for a TOF instrument providing a resolving power of 20,000 at full width at half maximum (FWHM). For the validation of HRMS analytical methods, widespread concepts such as the signal-to-noise ratios for the determination of decision limits and detection capabilities have shown to be not always applicable because in some cases almost no noise can be detected anymore. A statistical methodology providing a reliable alternative is extended and applied.

  5. Structures of polymeric pigments in red wine and their derived quantification markers revealed by high-resolution quadrupole time-of-flight mass spectrometry.

    PubMed

    Zeng, Liming; Teissèdre, Pierre-Louis; Jourdes, Michaël

    2016-01-15

    The quantification of polymeric pigment families in red wine through their derived quantification markers released during phloroglucinolysis will allow the understanding of their formation kinetics and evolutions during aging which has not been achieved until now and is in urgent need. The identification of these quantification markers was achieved by high-resolution mass spectrometry (HRMS) in this study. HRMS was used to clarify the fragmentation patterns in positive mode of polymeric pigments and identify their derived quantification markers released during phloroglucinolysis. With HRMS, identification of (epi)catechin-malvidin-3-O-glucoside adducts was simplified to MS/MS, and the fragmentation pattern of malvidin-3-O-glucoside-(epi)catechin adducts was clearly demonstrated. The attribution of four detected ions at m/z 1071.2765 in red wine to the trimeric structure of (epi)catechin-[malvidin-3-O-glucoside-A type linkage-(epi)catechin] and [malvidin-3-O-glucoside-A type linkage-(epi)catechin]-(epi)catechin was achieved for the first time by MS/MS and evidence given by phloroglucinolysis. Moreover, four kinds of derived quantification markers released from polymeric pigments during phloroglucinolysis were also identified. The fragmentation pathways of polymeric pigments in red wine and their derived quantification markers released during acidic chemical depolymerisation were clarified which will allow their quantification in red wine. Copyright © 2015 John Wiley & Sons, Ltd.

  6. Quantification of polychlorinated dibenzo-p-dioxins and dibenzofurans by direct injection of sample extract into the comprehensive multidimensional gas chromatograph/high-resolution time-of-flight mass spectrometer.

    PubMed

    Shunji, Hashimoto; Yoshikatsu, Takazawa; Akihiro, Fushimi; Hiroyasu, Ito; Kiyoshi, Tanabe; Yasuyuki, Shibata; Masa-aki, Ubukata; Akihiko, Kusai; Kazuo, Tanaka; Hideyuki, Otsuka; Katsunori, Anezaki

    2008-01-18

    Polychlorinated dibenzo-p-dioxins and dibenzofurans in crude extracts of fly ash and flue gas from municipal waste incinerators were quantified using a comprehensive multidimensional gas chromatograph (GC x GC) coupled to a high-resolution time-of-flight mass spectrometer (HR-TOFMS). For identification and quantification, we developed our own program to prepare 3D chromatograms of selected mass numbers from the data of the GC x GC/HR-TOFMS. Isolation of all congeners with a TCDD toxic equivalency factor from the other isomers by only one injection was confirmed. The instrumental detection limit of TCDD on the GC x GC/HR-TOFMS was 0.9 pg by the relative calibration method. Quantification of these substances in the crude extracts was achieved by direct injection to the GC x GC/HR-TOFMS. The results agree with the values obtained using a generic gas chromatography/high-resolution mass spectrometry (GC/HRMS) system. It was confirmed that measurement by high-resolution TOFMS and GC x GC effectively reduces interference from other chemicals.

  7. Qualitative analysis of a sulfur-fumigated Chinese herbal medicine by comprehensive two-dimensional gas chromatography and high-resolution time of flight mass spectrometry using colorized fuzzy difference data processing.

    PubMed

    Cai, Hao; Cao, Gang; Zhang, Hong-Yan

    2017-04-01

    To investigate the chemical transformation of volatile compounds in sulfur-fumigated Radix Angelicae Sinensis. A comprehensive two-dimensional gas chromatography (GC×GC) and high-resolution time-of-flight mass spectrometry (HR-TOF/MS) with colorized fuzzy difference (CFD) method was used to investigate the effect of sulfur-fumigation on the volatile components from Radix Angelicae Sinensis. Twenty-five compounds that were found in sun-dried samples disappeared in sulfur-fumigated samples. Seventeen volatile components including two sulfur-containing compounds were newly generated for the first time in volatile oils of sulfur-fumigated Radix Angelicae Sinensis. The strategy can be successfully applied to rapidly and holistically discriminate sun-dried and sulfur-fumigated Radix Angelicae Sinensis. GC×GC-HR-TOF/MS based CFD is a powerful and feasible approach for the global quality evaluation of Radix Angelicae Sinensis as well as other herbal medicines.

  8. Characterization of eleutheroside B metabolites derived from an extract of Acanthopanax senticosus Harms by high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry and automated data analysis.

    PubMed

    Lu, Fang; Sun, Qiang; Bai, Yun; Bao, Shunru; Li, Xuzhao; Yan, Guangli; Liu, Shumin

    2012-10-01

    We elucidated the structure and metabolite profile of eleutheroside B, a component derived from the extract of Acanthopanax senticosus Harms, after oral administration of the extract in rats. Samples of rat plasma were collected and analyzed by selective high-resolution liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) automated data analysis method. A total of 11 metabolites were detected: four were identified, and three of those four are reported for the first time here. The three new plasma metabolites were identified on the basis of mass fragmentation patterns and literature reports. The major in vivo metabolic processes associated with eleutheroside B in A. senticosus include demethylation, acetylation, oxidation and glucuronidation after deglycosylation. A fairly comprehensive metabolic pathway was proposed for eleutheroside B. Our results provide a meaningful basis for drug discovery, design and clinical applications related to A. senticosus in traditional Chinese medicine.

  9. Temperature Evolution of the Pseudogap and Superconducting Gap in Bi2 Sr2 CaCu2 O8 Superconductor Studied by High Resolution Time-of-Flight Laser-ARPES

    NASA Astrophysics Data System (ADS)

    Zhang, Yuxiao; Zhou, Xingjiang

    2015-03-01

    The relationship between the pseudogap and superconducting gap in high temperature cuprate superconductors remains an outstanding issue. In this talk, we will present our high resolution laser-ARPES measurement on Bi2Sr2CaCu2O8 superconductor. We will use the latest generation of ARPES system equipped with the VUV laser and the time-of-flight (TOF) electron energy analyzer. This enables us to have super-high energy resolution, high momentum resolution, simultaneous coverage of two-dimensional momentum space, high data acquisition efficiency and much reduced nonlinearity effect. From detailed temperature dependence near the nodal and antinodal regions, we will discuss on the relationship between the pseudogap and superconducting gap in the cuprate superconductors.

  10. Analysis of human plasma lipids by using comprehensive two-dimensional gas chromatography with dual detection and with the support of high-resolution time-of-flight mass spectrometry for structural elucidation.

    PubMed

    Salivo, Simona; Beccaria, Marco; Sullini, Giuseppe; Tranchida, Peter Q; Dugo, Paola; Mondello, Luigi

    2015-01-01

    The main focus of the present research is the analysis of the unsaponifiable lipid fraction of human plasma by using data derived from comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection. This approach enabled us to attain both mass spectral information and analyte percentage data. Furthermore, gas chromatography coupled with high-resolution time-of-flight mass spectrometry was used to increase the reliability of identification of several unsaponifiable lipid constituents. The synergism between both the high-resolution gas chromatography and mass spectrometry processes enabled us to attain a more in-depth knowledge of the unsaponifiable fraction of human plasma. Additionally, information was attained on the fatty acid and triacylglycerol composition of the plasma samples, subjected to investigation by using comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection and high-performance liquid chromatography with atmospheric pressure chemical ionization quadrupole mass spectrometry, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Simulation of Duty Cycle-Based Trapping and Ejection of Massive Ions Using Linear Digital Quadrupoles: the Enabling Technology for High Resolution Time-of-Flight Mass Spectrometry in the Ultra High Mass Range.

    PubMed

    Lee, Jeonghoon; Marino, Maxwell A; Koizumi, Hideya; Reilly, Peter T A

    2011-06-15

    Duty cycle-based trapping and extraction processes have been investigated for linear digitally-driven multipoles by simulating ion trajectories. The duty cycles of the applied waveforms were adjusted so that an effective trapping or ejection electric field was created between the rods and the grounded end cap electrodes. By manipulating the duty cycles of the waveforms, the potentials of the multipole rods can be set equal for part of the waveform cycle. When all rods are negative for this period, the device traps positive ions and when all are positive, it ejects them in focused trajectories. Four Linac II electrodes[1] have been added between the quadrupole rods along the asymptotes to create an electric field along the symmetry axis for collecting the ions near the exit end cap electrode and prompt ejection. This method permits the ions to be collected and then ejected in a concentrated and collimated plug into the acceleration region of a time-of-flight mass spectrometer (TOFMS). Our method has been shown to be independent of mass. Because the resolution of orthogonal acceleration TOFMS depends primarily on the dispersion of the ions injected into the acceleration region and not on the ion mass, this technology will enable high resolution in the ultrahigh mass range (m/z > 20,000).

  12. Observations of Processed Asian Pollution with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) from the C-130 Aircraft During the INTEX-B Field Campaign

    NASA Astrophysics Data System (ADS)

    Dunlea, E.; Decarlo, P.; Aiken, A.; Kimmel, J.; Bahreini, R.; Peltier, R.; Weber, R.; Tomlinson, J.; Collins, D.; Shinozuka, Y.; Howell, S.; Clarke, A.; Emmons, L.; Apel, E.; Pfister, G.; van Donkelaar, A.; Millet, D.; Jimenez, J.

    2007-12-01

    Measurements of submicron, non-refractory aerosol mass were made from the NCAR/NSF C-130 aircraft using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during the spring 2006 INTEX-B field campaign based in Seattle. We intercepted numerous Asian pollution layers, some after rapid transport across the Pacific and others after slower transport which had reduced aerosol concentrations and were depleted of short-lived tracers. The aerosol in Asian pollution layers intercepted over the Eastern Pacific Ocean was shown to have a predominance of sulfate over organic material, the latter being highly oxidized. Measurements and back trajectory calculations are consistent with the following sequence: (a) relatively more rapid conversion of organic precursors to organic aerosol compared to conversion of SO2 to sulfate just downwind of Asian urban centers and pollution sources, (b) uplift and transport of air masses resulting in washout of most aerosol material leaving relatively more SO2 available, and (c) subsequent SO2 to sulfate conversion as air masses are transported across the Pacific. This is consistent with Brock et al., JGR, 2004. Two case studies will be presented to describe this evolution of aerosol chemical composition during transport from Asia. Overall correlations of several tracers will be shown for comparing MOZART and GEOS-Chem model outputs with the measurements. Also, comparisons of AMS measurements with other aerosol instruments will be shown.

  13. Simulation of Duty Cycle-Based Trapping and Ejection of Massive Ions Using Linear Digital Quadrupoles: the Enabling Technology for High Resolution Time-of-Flight Mass Spectrometry in the Ultra High Mass Range

    PubMed Central

    Lee, Jeonghoon; Marino, Maxwell A.; Koizumi, Hideya; Reilly, Peter T. A.

    2011-01-01

    Duty cycle-based trapping and extraction processes have been investigated for linear digitally-driven multipoles by simulating ion trajectories. The duty cycles of the applied waveforms were adjusted so that an effective trapping or ejection electric field was created between the rods and the grounded end cap electrodes. By manipulating the duty cycles of the waveforms, the potentials of the multipole rods can be set equal for part of the waveform cycle. When all rods are negative for this period, the device traps positive ions and when all are positive, it ejects them in focused trajectories. Four Linac II electrodes[1] have been added between the quadrupole rods along the asymptotes to create an electric field along the symmetry axis for collecting the ions near the exit end cap electrode and prompt ejection. This method permits the ions to be collected and then ejected in a concentrated and collimated plug into the acceleration region of a time-of-flight mass spectrometer (TOFMS). Our method has been shown to be independent of mass. Because the resolution of orthogonal acceleration TOFMS depends primarily on the dispersion of the ions injected into the acceleration region and not on the ion mass, this technology will enable high resolution in the ultrahigh mass range (m/z > 20,000). PMID:21731427

  14. Real-time gas and particle-phase organic acids measurement at a forest site using chemical ionization high-resolution time-of-flight mass spectrometry during BEACHON-RoMBAS

    NASA Astrophysics Data System (ADS)

    Yatavelli, L. R.; Stark, H.; Kimmel, J.; Cubison, M.; Day, D. A.; Jayne, J.; Thornton, J. A.; Worsnop, D. R.; Jimenez, J. L.

    2011-12-01

    We present measurement of organic acids in gas and aerosol particles conducted in a ponderosa pine forest during July and August 2011 as part of the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS; http://tinyurl.com/BEACHON-RoMBAS). The measurement technique is based on chemical ionization, high-resolution time-of-flight mass spectrometry and utilizes a Micro-Orifice Volatilization Impactor [MOVI-CI-HR-ToFMS; Yatavelli et al., AS&T, 2010] to collect sub-micron aerosol particles while simultaneously measuring the gas-phase composition. The collected particles are subsequently analyzed by temperature-programmed thermal desorption. The reagent ion chosen for this campaign is the acetate anion (CH3C(O)O-, m/z 59), which reacts selectively via proton transfer with compounds that are stronger gas-phase acids than acetic acid [Veres et al., IJMS, 2008]. Preliminary results show substantial particle-phase concentrations of biogenic oxidation products such as hydroxy-glutaric acid, pinic acid, pinonic acid, and hydroxy-pinonic acid along with numerous lower and higher molecular weight organic acids. Correlations of the organic acid concentrations with meteorological, gas and aerosol parameters measured by other instrumentation are investigated in order to understand the formation, transformation, and partitioning of gas and particle-phase organic acids in a forested environment dominated by terpenes.

  15. Retrospective analysis by data processing tools for comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry: a challenge for matrix-rich sediment core sample from Tokyo Bay.

    PubMed

    Zushi, Yasuyuki; Hashimoto, Shunji; Tamada, Masafumi; Masunaga, Shigeki; Kanai, Yutaka; Tanabe, Kiyoshi

    2014-04-18

    Data processing tools for non-target analysis using comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) were developed and applied to a sediment core in Tokyo Bay, focusing on chlorinated compounds in this study. The processing tools were classified in two different methods: (1) the consecutive use of mass defect filter followed by artificial neutral loss scan (MDF/artificial NLS) as a qualitative non-target screening method and (2) Entire Domain Combined Spectra Extraction and Integration Program (ComSpec) and two-dimensional peak sentinel (T-SEN) as a semi-quantitative target screening method. MDF/artificial NLS as a non-target screening approach revealed that PCBs, followed by octachlorodibenzo dioxin (OCDD), were the main chlorinated compounds present in all sediment layers. Furthermore, unknown peaks thought to be chlorinated compounds were found in increasing numbers, some in increasing amounts. T-SEN and ComSpec as a target screening approach were adapted for automatic semi-quantitative analysis showed that, in decreasing concentration order, PCBs, OCDD, and dichlorodiphenyltrichloroethane and its metabolites (DDEs, DDDs) were the main chlorinated pollutants in the sediments. The complementary use of both techniques allows us to extract significant chlorinated pollutants, including non-targeted compounds. This retrospective analysis by this approach performed well even on matrix-rich sediment samples and provided us an interesting insight of historical trends of pollution in Tokyo Bay.

  16. Stir bar sorptive extraction and comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry for ultra-trace analysis of organochlorine pesticides in river water.

    PubMed

    Ochiai, Nobuo; Ieda, Teruyo; Sasamoto, Kikuo; Takazawa, Yoshikatsu; Hashimoto, Shunji; Fushimi, Akihiro; Tanabe, Kiyoshi

    2011-09-28

    A method for the determination of ultra-trace amounts of organochlorine pesticides (OCPs) in river water was developed by using stir bar sorptive extraction (SBSE) followed by thermal desorption and comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry (SBSE-TD-GC×GC-HRTOF-MS). SBSE conditions such as extraction time profiles, phase ratio (β: sample volume/polydimethylsiloxane (PDMS) volume), and modifier addition, were examined. Fifty milli-liter sample including 10% acetone was extracted for 3 h using stir bars with a length of 20 mm and coated with a 0.5 mm layer of PDMS (PDMS volume, 47 μL). The stir bar was thermally desorbed and subsequently analyzed by GC×GC-HRTOF-MS. The method showed good linearity over the concentration range from 50 to 1000 pg L(-1) or 2000 pg L(-1) for all analytes, and the correlation coefficients (r(2)) were greater than 0.9903 (except for β-HCH, r(2)=0.9870). The limit of detection (LOD) ranged from 10 to 44 pg L(-1). The method was successfully applied to the determination of 16 OCPs at pg L(-1) to ng L(-1) in river water. The results agree fairly well with the values obtained by a conventional liquid-liquid extraction (LLE)-GC-HRMS (selected ion monitoring: SIM) method using large sample volume (20 L). The method also allows screening of non-target compounds, e.g. pesticides and their degradation products, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pharmaceuticals and personal care products (PPCPs) and metabolites in the same river water sample, by using full spectrum acquisition with accurate mass in GC×GC. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Ultra-high pressure liquid chromatography-mass spectrometry for plant metabolomics: a systematic comparison of high-resolution quadrupole-time-of-flight and single stage Orbitrap mass spectrometers.

    PubMed

    Glauser, Gaetan; Veyrat, Nathalie; Rochat, Bertrand; Wolfender, Jean-Luc; Turlings, Ted C J

    2013-05-31

    The response of Arabidopsis to stress caused by mechanical wounding was chosen as a model to compare the performances of high resolution quadrupole-time-of-flight (Q-TOF) and single stage Orbitrap (Exactive Plus) mass spectrometers in untargeted metabolomics. Both instruments were coupled to ultra-high pressure liquid chromatography (UHPLC) systems set under identical conditions. The experiment was divided in two steps: the first analyses involved sixteen unwounded plants, half of which were spiked with pure standards that are not present in Arabidopsis. The second analyses compared the metabolomes of mechanically wounded plants to unwounded plants. Data from both systems were extracted using the same feature detection software and submitted to unsupervised and supervised multivariate analysis methods. Both mass spectrometers were compared in terms of number and identity of detected features, capacity to discriminate between samples, repeatability and sensitivity. Although analytical variability was lower for the UHPLC-Q-TOF, generally the results for the two detectors were quite similar, both of them proving to be highly efficient at detecting even subtle differences between plant groups. Overall, sensitivity was found to be comparable, although the Exactive Plus Orbitrap provided slightly lower detection limits for specific compounds. Finally, to evaluate the potential of the two mass spectrometers for the identification of unknown markers, mass and spectral accuracies were calculated on selected identified compounds. While both instruments showed excellent mass accuracy (<2.5ppm for all measured compounds), better spectral accuracy was recorded on the Q-TOF. Taken together, our results demonstrate that comparable performances can be obtained at acquisition frequencies compatible with UHPLC on Q-TOF and Exactive Plus MS, which may thus be equivalently used for plant metabolomics.

  18. Supra-aortic low-dose contrast-enhanced time-resolved magnetic resonance (MR) angiography at 3 T: comparison with time-of-flight MR angiography and high-resolution contrast-enhanced MR angiography.

    PubMed

    Lee, Youn-Joo; Kim, Bum-soo; Koo, Ja-Sung; Kim, Bom-Yi; Jang, Jinhee; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin

    2015-06-01

    Low-dose, time-resolved, contrast-enhanced, magnetic resonance angiography (TR-CEMRA) has been described previously; however, a comparative study between low dose TR-CEMRA and time-of-flight MRA (TOF-MRA) in the diagnosis of supra-aortic arterial stenosis has not yet been published. To demonstrate the feasibility and effectiveness of low-dose TR-CEMRA compared with TOF-MRA, using high-resolution contrast-enhanced MRA (HR-CEMRA) as the reference standard. This prospective study consisted of 30 consecutive patients. All patients underwent TOF-MRA of the neck and circle of Willis and supra-aortic HR-CEMRA, followed by supra-aortic low-dose TR-CEMRA. Gadoterate meglumine (Gd-DOTA, Dotarem(®), Guerbet, Roissy CdG Cedex, France) was injected at a dose of 0.1 mmol/kg for HR-CEMRA, followed by a 0.03 mmol/kg bolus for low-dose TR-CEMRA. Three readers evaluated the assessibility and image quality, and then two readers classified each stenosis into the following categories: normal (0-30%), mild stenosis (31-50%), moderate (51-70%), severe (71-99%), and occlusion. TR-CEMRA and HR-CEMRA showed a greater number of assessable arterial segments than TOF-MRA (P < 0.01). For TR-CEMRA, 29 cases showed within or better than the diagnostic range, whereas all 30 cases were in the diagnostic range for TOF-MRA and HR-CEMRA. For evaluation of stenosis in a total of 743 arterial segments, both TR-CEMRA and TOF-MRA results agreed with those of HR-CEMRA in 729 segments (98.1%), with excellent inter-observer agreement of TR-CEMRA; stenosis was overestimated in nine segments (1.2%) and underestimated in five segments (0.7%). For diagnosis of stenosis using 30% as the cut-off value on HR-CEMRA, the sensitivity and specificity were 88.2% and 99.3%, respectively, for the TR-CEMRA procedure, versus 94.1% and 99.6%, respectively, for TOF-MRA. Low-dose TR-CEMRA is feasible and effective in the diagnosis of supra-aortic arterial stenosis, and could be more useful option than TOF-MRA. © The

  19. A high-resolution time-of-flight chemical ionization mass spectrometer utilizing hydronium ions (H3O+ ToF-CIMS) for measurements of volatile organic compounds in the atmosphere

    NASA Astrophysics Data System (ADS)

    Yuan, Bin; Koss, Abigail; Warneke, Carsten; Gilman, Jessica B.; Lerner, Brian M.; Stark, Harald; de Gouw, Joost A.

    2016-07-01

    Proton transfer reactions between hydronium ions (H3O+) and volatile organic compounds (VOCs) provide a fast and highly sensitive technique for VOC measurements, leading to extensive use of proton-transfer-reaction mass spectrometry (PTR-MS) in atmospheric research. Based on the same ionization approach, we describe the development of a high-resolution time-of-flight chemical ionization mass spectrometer (ToF-CIMS) utilizing H3O+ as the reagent ion. The new H3O+ ToF-CIMS has sensitivities of 100-1000 cps ppb-1 (ion counts per second per part-per-billion mixing ratio of VOC) and detection limits of 20-600 ppt at 3σ for a 1 s integration time for simultaneous measurements of many VOC species of atmospheric relevance. The ToF analyzer with mass resolution (m/Δm) of up to 6000 allows the separation of isobaric masses, as shown in previous studies using similar ToF-MS. While radio frequency (RF)-only quadrupole ion guides provide better overall ion transmission than ion lens system, low-mass cutoff of RF-only quadrupole causes H3O+ ions to be transmitted less efficiently than heavier masses, which leads to unusual humidity dependence of reagent ions and difficulty obtaining a humidity-independent parameter for normalization. The humidity dependence of the instrument was characterized for various VOC species and the behaviors for different species can be explained by compound-specific properties that affect the ion chemistry (e.g., proton affinity and dipole moment). The new H3O+ ToF-CIMS was successfully deployed on the NOAA WP-3D research aircraft for the SONGNEX campaign in spring of 2015. The measured mixing ratios of several aromatics from the H3O+ ToF-CIMS agreed within ±10 % with independent gas chromatography measurements from whole air samples. Initial results from the SONGNEX measurements demonstrate that the H3O+ ToF-CIMS data set will be valuable for the identification and characterization of emissions from various sources, investigation of secondary

  20. Screening of additives in plastics with high resolution time-of-flight mass spectrometry and different ionization sources: direct probe injection (DIP)-APCI, LC-APCI, and LC-ion booster ESI.

    PubMed

    Ballesteros-Gómez, Ana; Jonkers, Tim; Covaci, Adrian; de Boer, Jacob

    2016-04-01

    Plastics are complex mixtures consisting of a polymer and additives with different physico-chemical properties. We developed a broad screening method to elucidate the nature of compounds present in plastics used in electrical/electronic equipment commonly found at homes (e.g., electrical adaptors, computer casings, heaters). The analysis was done by (a) solvent extraction followed by liquid chromatography coupled to high accuracy/resolution time-of-flight mass spectrometry (TOFMS) with different ionization sources or (b) direct analysis of the solid by ambient mass spectrometry high accuracy/resolution TOFMS. The different ionization methods showed different selectivity and sensitivity for the different compound classes and were complementary. A variety of antioxidants, phthalates, UV filters, and flame retardants were found in most samples. Furthermore, some recently reported impurities or degradation products derived from flame retardants were identified, such as hydroxylated triphenyl phosphate and tetrabromobisphenol A monoglycidyl ether.

  1. Ultra high performance liquid chromatography-time-of-flight high resolution mass spectrometry in the analysis of hexabromocyclododecane diastereomers: method development and comparative evaluation versus ultra high performance liquid chromatography coupled to Orbitrap high resolution mass spectrometry and triple quadrupole tandem mass spectrometry.

    PubMed

    Zacs, D; Rjabova, J; Pugajeva, I; Nakurte, I; Viksna, A; Bartkevics, V

    2014-10-31

    An efficient ultra high performance liquid chromatography (UHPLC)-time-of-flight high resolution mass spectrometry (TOF-HRMS) method was elaborated for the determination of hexabromocyclododecane (HBCD) diastereomers in fish samples and compared against UHPLC-Orbitrap-HRMS and UHPLC-triple quadrupole (QqQ) tandem MS (MS/MS) techniques. The TOF-HRMS analyzer was operated at high resolution (>10000 full width at half maximum (FWHM)) with scanning the m/z range from 600 to 700, to achieve picogram quantitation limits. The effects of various operational parameters on the instrumental response were systematically investigated. Evaluation of the influence of sample clean-up procedure steps on signal suppression effect including removal of the matrix components by means of destructive acidic treatment or non-destructive gel permeation chromatography (GPC), and additional Florisil column chromatography step showed that the analytical response of UHPLC-TOF-HRMS system is much more affected by the presence of matrix components in the final extracts in comparison with UHPLC-Orbitrap-HRMS and UHPLC-QqQ-MS/MS systems. The method was robustly validated and used for the analysis of eel (Anquilla anquilla) samples originating from a Latvian lake. UHPLC-TOF-HRMS showed a suitable performance under the optimized conditions: recoveries for three selected diastereomers in the range of 99-116%; repeatability and intermediate precision expressed as relative standard deviation (RSD) in the ranges of 2.3-7.1% and 2.9-8.1%, respectively. The elaborated method achieved instrumental limits of quantification (i-LOQ) of 0.9-4.5pg on column that were suitable for the trace analysis of three HBCD diastereomers, corresponding to the method limits of quantification (m-LOQ) of 7.0-29pgg(-1) wet weight (w.w.). The efficiency of UHPLC-TOF-HRMS method was evaluated by comparing the performance characteristics and analytical data from real samples with the validation data and real sample results

  2. Evaluation of the composition of vine shoots and oak chips for oenological purposes by superheated liquid extraction and high-resolution liquid chromatography-time-of-flight/mass spectrometry analysis.

    PubMed

    Delgado de la Torre, M Pilar; Priego-Capote, Feliciano; Luque de Castro, María Dolores

    2012-04-04

    Vine shoots are characterized in this research and compared to oak chips, frequently employed in the aging of wine or spirits. For this purpose, liquid chromatography-diode array detection and liquid chromatography-time-of-flight/mass spectrometry (LC-TOF/MS) analyses of hydroalcoholic extracts from vine shoots pertaining to 18 different vine varieties and from five varieties of oak chips have been carried out. The concentrations of a representative panel of interesting compounds from an oenological point of view have been compared in the extracts, finding similarity patterns for many of them. The analysis by LC-TOF/MS in high accuracy mode has led to the identification of numerous compounds in the hydroalcoholic extracts. The statistical analysis has enabled identification of the vine-shoot varieties providing extracts with more similar composition to that given by extracts from oak chips. Therefore, these vine-shoots varieties are suitable to be presented as an alternative to the use of oak barrels or oak chips in the aging process of wine and spirits.

  3. An integrated strategy for rapid and accurate determination of free and cell-bound microcystins and related peptides in natural blooms by liquid chromatography-electrospray-high resolution mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry using both positive and negative ionization modes.

    PubMed

    Flores, Cintia; Caixach, Josep

    2015-08-14

    An integrated high resolution mass spectrometry (HRMS) strategy has been developed for rapid and accurate determination of free and cell-bound microcystins (MCs) and related peptides in water blooms. The natural samples (water and algae) were filtered for independent analysis of aqueous and sestonic fractions. These fractions were analyzed by MALDI-TOF/TOF-MS and ESI-Orbitrap-HCD-MS. MALDI, ESI and the study of fragmentation sequences have been provided crucial structural information. The potential of combined positive and negative ionization modes, full scan and fragmentation acquisition modes (TOF/TOF and HCD) by HRMS and high resolution and accurate mass was investigated in order to allow unequivocal determination of MCs. Besides, a reliable quantitation has been possible by HRMS. This composition helped to decrease the probability of false positives and negatives, as alternative to commonly used LC-ESI-MS/MS methods. The analysis was non-target, therefore covered the possibility to analyze all MC analogs concurrently without any pre-selection of target MC. Furthermore, archived data was subjected to retrospective "post-targeted" analysis and a screening of other potential toxins and related peptides as anabaenopeptins in the samples was done. Finally, the MS protocol and identification tools suggested were applied to the analysis of characteristic water blooms from Spanish reservoirs.

  4. Solid phase microextraction coupled with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for high-resolution metabolite profiling in apples: implementation of structured separations for optimization of sample preparation procedure in complex samples.

    PubMed

    Risticevic, Sanja; DeEll, Jennifer R; Pawliszyn, Janusz

    2012-08-17

    Metabolomics currently represents one of the fastest growing high-throughput molecular analysis platforms that refer to the simultaneous and unbiased analysis of metabolite pools constituting a particular biological system under investigation. In response to the ever increasing interest in development of reliable methods competent with obtaining a complete and accurate metabolomic snapshot for subsequent identification, quantification and profiling studies, the purpose of the current investigation is to test the feasibility of solid phase microextraction for advanced fingerprinting of volatile and semivolatile metabolites in complex samples. In particular, the current study is focussed on the development and optimization of solid phase microextraction (SPME) - comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-ToFMS) methodology for metabolite profiling of apples (Malus × domestica Borkh.). For the first time, GC × GC attributes in terms of molecular structure-retention relationships and utilization of two-dimensional separation space on orthogonal GC × GC setup were exploited in the field of SPME method optimization for complex sample analysis. Analytical performance data were assessed in terms of method precision when commercial coatings are employed in spiked metabolite aqueous sample analysis. The optimized method consisted of the implementation of direct immersion SPME (DI-SPME) extraction mode and its application to metabolite profiling of apples, and resulted in a tentative identification of 399 metabolites and the composition of a metabolite database far more comprehensive than those obtainable with classical one-dimensional GC approaches. Considering that specific metabolome constituents were for the first time reported in the current study, a valuable approach for future advanced fingerprinting studies in the field of fruit biology is proposed. The current study also intensifies the understanding of SPME

  5. Gas Cluster Ion Beam Time-of-Flight Secondary Ion Mass Spectrometry High-Resolution Imaging of Cardiolipin Speciation in the Brain: Identification of Molecular Losses after Traumatic Injury.

    PubMed

    Tian, Hua; Sparvero, Louis J; Amoscato, Andrew A; Bloom, Anna; Bayır, Hülya; Kagan, Valerian E; Winograd, Nicholas

    2017-03-29

    Gas cluster ion beam-secondary ion mass spectrometry (GCIB-SIMS) has shown the full potential of mapping intact lipids in biological systems with better than 10 μm lateral resolution. This study investigated further the capability of GCIB-SIMS in imaging high-mass signals from intact cardiolipin (CL) and gangliosides in normal brain and the effect of a controlled cortical impact model (CCI) of traumatic brain injury (TBI) on their distribution. A combination of enzymatic and chemical treatments was employed to suppress the signals from the most abundant phospholipids (phosphatidylcholine (PC) and phosphatidylethanolamine (PE)) and enhance the signals from the low-abundance CLs and gangliosides to allow their GCIB-SIMS detection at 8 and 16 μm spatial resolution. Brain CLs have not been observed previously using other contemporary imaging mass spectrometry techniques at better than 50 μm spatial resolution. High-resolution images of naive and injured brain tissue facilitated the comparison of CL species across three multicell layers in the CA1, CA3, and DG regions of the hippocampus. GCIB-SIMS also reliably mapped losses of oxidizable polyunsaturated CL species (but not the oxidation-resistant saturated and monounsaturated gangliosides) to regions including the CA1 and CA3 of the hippocampus after CCI. This work extends the detection range for SIMS measurements of intact lipids to above m/z 2000, bridging the mass range gap compared with MALDI. Further advances in high-resolution SIMS of CLs, with the potential for single cell or supra-cellular imaging, will be essential for the understanding of CL's functional and structural organization in normal and injured brain.

  6. Collins Aerodyne VTOL aircraft investigations

    NASA Image and Video Library

    1960-01-11

    Collins Aerodyne vertical take-off and landing (VTOL) aircraft investigations. Ground plane support system. 3/4 front view. Dave Koening (from Collins Aerodyne) in photo. Mounted on variable height struts, ground board system, zero degree angle of attack. 01/11/1960

  7. Analysis of the unsaponifiable fraction of lipids belonging to various milk-types by using comprehensive two-dimensional gas chromatography with dual mass spectrometry/flame ionization detection and with the support of high resolution time-of-flight mass spectrometry for structural elucidation.

    PubMed

    Tranchida, Peter Q; Salivo, Simona; Bonaccorsi, Ivana; Rotondo, Archimede; Dugo, Paola; Mondello, Luigi

    2013-10-25

    The present investigation is focused on the use of a comprehensive two-dimensional GC (GC×GC) method, with dual mass spectrometry/flame ionization detection (MS/FID), for the qualitative and quantitative analysis of the unsaponifiable fraction of milk lipids (cow butter, buffalo, ewe, and goat milks). The structure of many constituents (particularly sterols) was confirmed by using GC-high resolution time-of-flight MS. The GC×GC column set used consisted of a low-polarity first dimension, and a medium-polarity secondary one, both characterized by a high thermal stability. The use of dual detection enabled the attainment of both mass spectral information and relative % FID data. The complexity of the fingerprint, generated by the unsaponifiable fraction, justified the employment of the two-dimensional GC technology. However, it was two other GC×GC characteristics that contributed most to the attainment of promising results, namely sensitivity enhancement and the formation of group-type patterns. Because many milk lipid constituents were not contained in the MS databases employed, exact mass information proved to be valuable for identification purposes.

  8. Time of flight mass spectrometer

    DOEpatents

    Ulbricht, Jr., William H.

    1984-01-01

    A time-of-flight mass spectrometer is described in which ions are desorbed from a sample by nuclear fission fragments, such that desorption occurs at the surface of the sample impinged upon by the fission fragments. This configuration allows for the sample to be of any thickness, and eliminates the need for complicated sample preparation.

  9. Miniature Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Potember, Richard S.

    1999-01-01

    Major advances must occur to protect astronauts from prolonged periods in near-zero gravity and high radiation associated with extended space travel. The dangers of living in space must be thoroughly understood and methods developed to reverse those effects that cannot be avoided. Six of the seven research teams established by the National Space Biomedical Research Institute (NSBRI) are studying biomedical factors for prolonged space travel to deliver effective countermeasures. To develop effective countermeasures, each of these teams require identification of and quantitation of complex pharmacological, hormonal, and growth factor compounds (biomarkers) in humans and in experimental animals to develop an in-depth knowledge of the physiological changes associated with space travel. At present, identification of each biomarker requires a separate protocol. Many of these procedures are complicated and the identification of each biomarker requires a separate protocol and associated laboratory equipment. To carry all of this equipment and chemicals on a spacecraft would require a complex clinical laboratory; and it would occupy much of the astronauts time. What is needed is a small, efficient, broadband medical diagnostic instrument to rapidly identify important biomarkers for human space exploration. The Miniature Time-Of- Flight Mass Spectrometer Project in the Technology Development Team is developing a small, high resolution, time-of-flight mass spectrometer (TOFMS) to quantitatively measure biomarkers for human space exploration. Virtues of the JHU/APL TOFMS technologies reside in the promise for a small (less than one cubic ft), lightweight (less than 5 kg), low-power (less than 50 watts), rugged device that can be used continuously with advanced signal processing diagnostics. To date, the JHU/APL program has demonstrated mass capability from under 100 to beyond 10,000 atomic mass units (amu) in a very small, low power prototype for biological analysis. Further

  10. Miniature Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Potember, Richard S.

    1999-01-01

    Major advances must occur to protect astronauts from prolonged periods in near-zero gravity and high radiation associated with extended space travel. The dangers of living in space must be thoroughly understood and methods developed to reverse those effects that cannot be avoided. Six of the seven research teams established by the National Space Biomedical Research Institute (NSBRI) are studying biomedical factors for prolonged space travel to deliver effective countermeasures. To develop effective countermeasures, each of these teams require identification of and quantitation of complex pharmacological, hormonal, and growth factor compounds (biomarkers) in humans and in experimental animals to develop an in-depth knowledge of the physiological changes associated with space travel. At present, identification of each biomarker requires a separate protocol. Many of these procedures are complicated and the identification of each biomarker requires a separate protocol and associated laboratory equipment. To carry all of this equipment and chemicals on a spacecraft would require a complex clinical laboratory; and it would occupy much of the astronauts time. What is needed is a small, efficient, broadband medical diagnostic instrument to rapidly identify important biomarkers for human space exploration. The Miniature Time-Of- Flight Mass Spectrometer Project in the Technology Development Team is developing a small, high resolution, time-of-flight mass spectrometer (TOFMS) to quantitatively measure biomarkers for human space exploration. Virtues of the JHU/APL TOFMS technologies reside in the promise for a small (less than one cubic ft), lightweight (less than 5 kg), low-power (less than 50 watts), rugged device that can be used continuously with advanced signal processing diagnostics. To date, the JHU/APL program has demonstrated mass capability from under 100 to beyond 10,000 atomic mass units (amu) in a very small, low power prototype for biological analysis. Further

  11. Time-of-flight measurements

    NASA Astrophysics Data System (ADS)

    Atwood, W. B.

    1980-10-01

    Time of flight measurements are used in high energy particle physics experiments to: (1) distinguish background from events; and (2) identify particle types. An example of background separation is shown. The reaction studied was e + p e prime + p prime + X where the e(p) stand for an initial and detected electron (proton) and X is a produced but undetected final state with a mass in the rho meson region. The relative time between the detection of an electron and a proton in two of the spectrometers in End Station A is plotted. Data for two different kinematic settings taken in the experiment are shown. The time resolution has been partially corrected for the various flight paths through the instruments and the difference in time resolutions between the two settings results mainly from the incompleteness of this correction. The signal height above the background depends on the time resolution, (DELTA) tau. The chance background is proportional to the product of the electron counting rate, the proton counting rate, and (DELTA) tau.

  12. Time-of-flight measurements

    SciTech Connect

    Atwood, W.B.

    1980-10-01

    Time of flight (TOF) measurements are used in high energy particle physics experiments to: (1) distinguish background from events and (2) identify particle types. An example of background separation is shown. These data come from a coincidence electro-production experiment performed at SLAC. The reaction being studied was e + p ..-->.. e' + p' + X where the e(p) stand for an initial and detected electron (proton) and X is a produced but undetected final state with a mass in the rho meson region. The relative time between the detection of an electron and a proton in two of the spectrometers in End Station A is plotted. Data for two different kinematic settings taken in the experiment are shown. The time resolution has been partially corrected for the various flight paths through the instruments and the difference in time resolutions between the two settings results mainly from the incompleteness of this correction. The signal height above the background depends on the time resolution, ..delta.. tau. The chance background is proportional to the product of the electron counting rate, the proton counting rate, and ..delta.. tau. Smaller ..delta.. tau means that higher electron and proton counting rates may be tolerated and result in a similar signal-to-noise ratio.

  13. Inexpensive Time-of-Flight Velocity Measurements.

    ERIC Educational Resources Information Center

    Everett, Glen E.; Wild, R. L.

    1979-01-01

    Describes a circuit designed to measure time-of-flight velocity and shows how to use it to determine bullet velocity in connection with the ballistic pendulum demonstration of momentum conservation. (Author/GA)

  14. Inexpensive Time-of-Flight Velocity Measurements.

    ERIC Educational Resources Information Center

    Everett, Glen E.; Wild, R. L.

    1979-01-01

    Describes a circuit designed to measure time-of-flight velocity and shows how to use it to determine bullet velocity in connection with the ballistic pendulum demonstration of momentum conservation. (Author/GA)

  15. Laser assisted reflectron time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Mamyrin, B. A.

    1994-02-01

    Pulsed-mode laser assisted ionization schemes are extensively used in connection with time-of-flight mass spectrometric techniques, particularly when large-mass, thermally labile molecules i.e. biomolecules, proteins, and DNA have to be analysed. Along with the high resolution accomplished with the introduction of the reflector fields, these techniques have received considerable attention, in particular due to their ability to record a mass spectrum over the whole mass range with each single pulse. It is also important to note that the ionization volume (the space in which ions are created) can be considerably larger than in static mass spectrometers and with essentially unlimited mass-range. Furthermore, the sensitivity of laser-assisted reflectron time-of-flight mass spectrometry can almost reach its physical limit (a few atoms or molecules). Many modifications of laser assisted reflectrons have been developed. The key differences reside, on the one hand in the methods employed to focus the times-of-flight of the ions on the detector, and on the other hand with the specific sources used. One can expect to witness in the near future an ever increasing interest in these techniques with a wide range of new applications in fundamental and applied science or technologies such as materials science, analytical chemistry, pharmacology, biochemistry and genetics, to cite only a few.

  16. Time of flight Laue fiber diffraction studies of perdeuterated DNA

    SciTech Connect

    Forsyth, V.T.; Whalley, M.A.; Mahendrasingam, A.; Fuller, W.

    1994-12-31

    The diffractometer SXD at the Rutherford Appleton Laboratory ISIS pulsed neutron source has been used to record high resolution time-of-flight Laue fiber diffraction data from DNA. These experiments, which are the first of their kind, were undertaken using fibers of DNA in the A conformation and prepared using deuterated DNA in order to minimis incoherent background scattering. These studies complement previous experiments on instrument D19 at the Institute Laue Langevin using monochromatic neutrons. Sample preparation involved drawing large numbers of these deuterated DNA fibers and mounting them in a parallel array. The strategy of data collection is discussed in terms of camera design, sample environment and data collection. The methods used to correct the recorded time-of-flight data and map it into the final reciprocal space fiber diffraction dataset are also discussed. Difference Fourier maps showing the distribution of water around A-DNA calculated on the basis of these data are compared with results obtained using data recorded from hydrogenated A-DNA on D19. Since the methods used for sample preparation, data collection and data processing are fundamentally different for the monochromatic and Laue techniques, the results of these experiments also afford a valuable opportunity to independently test the data reduction and analysis techniques used in the two methods.

  17. Time-of-flight radio location system

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A bi-static radar configuration measures the direct time-of-flight of a transmitted RF pulse and is capable of measuring this time-of-flight with a jitter on the order of about one pico-second, or about 0.01 inch of free space distance for an electromagnetic pulse over a range of about one to ten feet. A transmitter transmits a sequence of electromagnetic pulses in response to a transmit timing signal, and a receiver samples the sequence of electromagnetic pulses with controlled timing in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the sequence of electromagnetic pulses such that the time between transmission of pulses in the sequence and sampling by the receiver sweeps over a range of delays. The receive timing signal sweeps over the range of delays in a sweep cycle such that pulses in the sequence are sampled at the pulse repetition rate, and with different delays in the range of delays to produce a sample signal representing magnitude of a received pulse in equivalent time. Automatic gain control circuitry in the receiver controls the magnitude of the equivalent time sample signal. A signal processor analyzes the sample signal to indicate the time-of-flight of the electromagnetic pulses in the sequence.

  18. Time-of-flight radio location system

    DOEpatents

    McEwan, T.E.

    1996-04-23

    A bi-static radar configuration measures the direct time-of-flight of a transmitted RF pulse and is capable of measuring this time-of-flight with a jitter on the order of about one pico-second, or about 0.01 inch of free space distance for an electromagnetic pulse over a range of about one to ten feet. A transmitter transmits a sequence of electromagnetic pulses in response to a transmit timing signal, and a receiver samples the sequence of electromagnetic pulses with controlled timing in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the sequence of electromagnetic pulses such that the time between transmission of pulses in the sequence and sampling by the receiver sweeps over a range of delays. The receive timing signal sweeps over the range of delays in a sweep cycle such that pulses in the sequence are sampled at the pulse repetition rate, and with different delays in the range of delays to produce a sample signal representing magnitude of a received pulse in equivalent time. Automatic gain control circuitry in the receiver controls the magnitude of the equivalent time sample signal. A signal processor analyzes the sample signal to indicate the time-of-flight of the electromagnetic pulses in the sequence. 7 figs.

  19. Time-of-flight radio location system

    DOEpatents

    McEwan, Thomas E.

    1997-01-01

    A bi-static radar configuration measures the direct time-of-flight of a transmitted RF pulse and is capable of measuring this time-of-flight with a jitter on the order of about one pico-second, or about 0.01 inch of free space distance for an electromagnetic pulse over a range of about one to ten feet. A transmitter transmits a sequence of electromagnetic pulses in response to a transmit timing signal, and a receiver samples the sequence of electromagnetic pulses with controlled timing in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the sequence of electromagnetic pulses such that the time between transmission of pulses in the sequence and sampling by the receiver sweeps over a range of delays. The receive timing signal sweeps over the range of delays in a sweep cycle such that pulses in the sequence are sampled at the pulse repetition rate, and with different delays in the range of delays to produce a sample signal representing magnitude of a received pulse in equivalent time. Automatic gain control circuitry in the receiver controls the magnitude of the equivalent time sample signal. A signal processor analyzes the sample signal to indicate the time-of-flight of the electromagnetic pulses in the sequence. The sample signal in equivalent time is passed through an envelope detection circuit, formed of an absolute value circuit followed by a low pass filter, to convert the sample signal to a unipolar signal to eliminate effects of antenna misorientation.

  20. Time-of-flight radio location system

    DOEpatents

    McEwan, T.E.

    1997-08-26

    A bi-static radar configuration measures the direct time-of-flight of a transmitted RF pulse and is capable of measuring this time-of-flight with a jitter on the order of about one pico-second, or about 0.01 inch of free space distance for an electromagnetic pulse over a range of about one to ten feet. A transmitter transmits a sequence of electromagnetic pulses in response to a transmit timing signal, and a receiver samples the sequence of electromagnetic pulses with controlled timing in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the sequence of electromagnetic pulses such that the time between transmission of pulses in the sequence and sampling by the receiver sweeps over a range of delays. The receive timing signal sweeps over the range of delays in a sweep cycle such that pulses in the sequence are sampled at the pulse repetition rate, and with different delays in the range of delays to produce a sample signal representing magnitude of a received pulse in equivalent time. Automatic gain control circuitry in the receiver controls the magnitude of the equivalent time sample signal. A signal processor analyzes the sample signal to indicate the time-of-flight of the electromagnetic pulses in the sequence. The sample signal in equivalent time is passed through an envelope detection circuit, formed of an absolute value circuit followed by a low pass filter, to convert the sample signal to a unipolar signal to eliminate effects of antenna misorientation. 8 figs.

  1. Time-of-flight Fourier UCN spectrometer

    NASA Astrophysics Data System (ADS)

    Kulin, G. V.; Frank, A. I.; Goryunov, S. V.; Kustov, D. V.; Geltenbort, P.; Jentschel, M.; Lauss, B.; Schmidt-Wellenburg, P.

    2016-05-01

    We describe a new time-of-flight Fourier spectrometer for investigation of UCN diffraction by a moving grating. The device operates in the regime of a discrete set of modulation frequencies. The results of the first experiments show that the spectrometer may be used for obtaining UCN energy spectra in the energy range of 60 - 200 neV with a resolution of about 5 neV. The accuracy of determination of the line position was estimated to be several units of 10-10 eV.

  2. The TORCH time-of-flight detector

    NASA Astrophysics Data System (ADS)

    Harnew, N.; Brook, N.; Castillo García, L.; Cussans, D.; Föhl, K.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Piedigrossi, D.; Rademacker, J.; Ros Garcia, A.; van Dijk, M.

    2016-07-01

    The TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10 GeV/c momentum over a flight distance of 10 m. TORCH is designed for large-area coverage, up to 30 m2, and has a DIRC-like construction. The goal is to achieve a 15 ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10 mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53 mm2 Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40 ps per photon and it will have a lifetime of up to at least 5 Ccm-2 of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described.

  3. The CDF Time of Flight Detector

    SciTech Connect

    S. Cabrera et al.

    2004-01-06

    A new Time of Flight (TOF) detector based on scintillator bars with fine-mesh photomultipliers at both ends has been in operation since 2001 in the CDF experiment. With a design resolution of 100 ps, the TOF can provide separation between K{sup +-} and {pi}{sup +-} in p{bar p} collisions at the 2{omega} level for low momentum, which enhances b flavor tagging capabilities. Because of its very fast response, the TOF is an excellent triggering device, and it is used to trigger on highly ionizing particles, multiple minimum ionizing particles and cosmic rays. Particle identification is achieved by comparing the time-of-flight of the particle measured by the TOF to the time expected for a given mass hypothesis. In order to obtain the resolution necessary for particle ID, optimal calibrations are critical. This paper describes the TOF detector, its calibration procedure, the achieved resolution, the long term operation performances and some of the first results from data analysis using this detector.

  4. Time-of-Flight Microwave Camera.

    PubMed

    Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

    2015-10-05

    Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable "stealth" regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz-12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows "camera-like" behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum.

  5. Astronomical time-of-flight photon speedometer

    NASA Astrophysics Data System (ADS)

    Miller, J. B.; Miller, T. E.; Hoffert, M. J.; Dingle, L. A.; Harwell, R.; Hayes, E.

    2017-09-01

    A dual-band, fiber-optic, photon time-of-flight instrument was developed. Its design was optimized for measuring the velocity of visible photons emanating from relatively dim astronomical sources (apparent magnitude m >12 ), such as distant galaxies and quasars. We report the first direct photon group velocity measurements for extragalactic objects. The photon group velocity is found to be 3.00 ±0.03 ×1 08 m s -1 and is invariant, within experimental error, over the range of redshifts measured (0 ≤z ≤1.33 ). This measurement provides additional validation of general relativity and is consistent with the Friedmann-Lemaître-Robertson-Walker and hyperbolic anti-de Sitter metrics but not with the elliptical de Sitter metric.

  6. Time of flight system on a chip

    NASA Technical Reports Server (NTRS)

    Paschalidis, Nicholas P. (Inventor)

    2006-01-01

    A CMOS time-of-flight TOF system-on-a-chip SoC for precise time interval measurement with low power consumption and high counting rate has been developed. The analog and digital TOF chip may include two Constant Fraction Discriminators CFDs and a Time-to-Digital Converter TDC. The CFDs can interface to start and stop anodes through two preamplifiers and perform signal processing for time walk compensation (110). The TDC digitizes the time difference with reference to an off-chip precise external clock (114). One TOF output is an 11-bit digital word and a valid event trigger output indicating a valid event on the 11-bit output bus (116).

  7. Miniaturised Time-of-Flight Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Rohner, U.; Benz, W.; Whitby, J. A.; Wurz, P.; Schulz, R.; Romstedt, J.

    2004-04-01

    Originally intended for the European Space Agency's BepiColombo mission to Mercury, we have built a series of highly miniaturised laser ablation time of flight mass spectrometers (LMS), suitable for in situ measurements of the elemental and isotopic composition of the surface of airless planetary bodies. The instruments will determine ma jor, minor, and trace element abundances in minerals on a spatial scale of 10 m, and will have sufficient dynamic range and mass resolution to perform useful isotopic measurements in favourable cases. Solid material is simultaneously evaporated and ionised by means of laser ablation, requiring intense pulsed laser radiation. Laser ablation was chosen as the sample introduction technique principally because of its high spatial resolution and the lack of any need for sample preparation. Advantages of the technique include simplicity of the resulting design, speed of measurement, and the ability for depth profiling (potentially important for a regolith in which mineral grains are coated with impact produced glass). Time of flight mass spectrometers are simple, robust devices that couple well to a pulsed ion source and we have previous experience of their construction for space flight, e.g. the ROSINA instrument suite for the ROSETTA mission. For BepiColombo, we have built two prototype instruments, one with a design mass of 500 g and a volume comparable to a beer can intended to be deployed on a static lander, and a smaller cigarettebox sized version with a design mass of 250 g, small enough to be integrated in a rover or robotic arm.

  8. Limitation of Time-of-Flight Resolution in the Ultra High Mass Range

    PubMed Central

    Lee, Jeonghoon

    2011-01-01

    In this work, we have examined the reason for the deterioration of resolution and mass accuracy of time-of-flight mass analyzers with increasing mass after the expansion induced kinetic energy has been eliminated by collisional cooling in an ion guide. Theoretically, removing the expansion–induced kinetic energy by collisional cooling permits the ions to travel along the ion guide axes without significant deviation so that they can be injected into the analyzer in a well-collimated ion beam with well-defined kinetic energy. If the ions can be injected into an orthogonal acceleration time-of-flight mass analyzer (oa-TOF) in this manner, high resolution mass analysis can be obtained regardless of mass or m/z. Unfortunately, high resolution did not result. It is our contention that the effusive expansion out of the first ion guide yields dispersive axial ejection that reduces TOF resolving power with increasing mass not m/z. PMID:21728303

  9. Time-of-Flight Microwave Camera

    PubMed Central

    Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

    2015-01-01

    Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable “stealth” regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz–12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows “camera-like” behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum. PMID:26434598

  10. Time-of-Flight Microwave Camera

    NASA Astrophysics Data System (ADS)

    Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

    2015-10-01

    Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable “stealth” regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz-12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows “camera-like” behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum.

  11. Advances in time-of-flight PET

    PubMed Central

    Surti, Suleman; Karp, Joel S.

    2016-01-01

    This paper provides a review and an update on time-of-flight PET imaging with a focus on PET instrumentation, ranging from hardware design to software algorithms. We first present a short introduction to PET, followed by a description of TOF PET imaging and its history from the early days. Next, we introduce the current state-of-art in TOF PET technology and briefly summarize the benefits of TOF PET imaging. This is followed by a discussion of the various technological advancements in hardware (scintillators, photo-sensors, electronics) and software (image reconstruction) that have led to the current widespread use of TOF PET technology, and future developments that have the potential for further improvements in the TOF imaging performance. We conclude with a discussion of some new research areas that have opened up in PET imaging as a result of having good system timing resolution, ranging from new algorithms for attenuation correction, through efficient system calibration techniques, to potential for new PET system designs. PMID:26778577

  12. Advances in time-of-flight PET.

    PubMed

    Surti, Suleman; Karp, Joel S

    2016-01-01

    This paper provides a review and an update on time-of-flight PET imaging with a focus on PET instrumentation, ranging from hardware design to software algorithms. We first present a short introduction to PET, followed by a description of TOF PET imaging and its history from the early days. Next, we introduce the current state-of-art in TOF PET technology and briefly summarize the benefits of TOF PET imaging. This is followed by a discussion of the various technological advancements in hardware (scintillators, photo-sensors, electronics) and software (image reconstruction) that have led to the current widespread use of TOF PET technology, and future developments that have the potential for further improvements in the TOF imaging performance. We conclude with a discussion of some new research areas that have opened up in PET imaging as a result of having good system timing resolution, ranging from new algorithms for attenuation correction, through efficient system calibration techniques, to potential for new PET system designs. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. Development of An Ion-Drift Time-of-Flight Chemical Ionization Mass Spectrometry Technique for Measurements of Aerosol Precursor Gases

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Ma, Y.; Chen, M.

    2012-12-01

    We have developed a new technique, i.e., ion-drift time-of-flight chemical ionization mass spectrometry (ID-ToF-CIMS) for measurements of aerosol precursor gases, including ammonia, amines, organic acids and oxygenated VOCs at pptv level with a response time less than 1 s. The ID-ToF-CIMS was modified from an Aerodyne high resolution ToF-CIMS with a custom-designed ion-drift tube, which can control the ion flight velocity and hence the ion-molecular reaction time. In addition, the tunable electric field generated by the drift tube can break up water clusters to select the major reagent ions. The advantages of the ID-ToF-CIMS over the traditional quadrupole-based ID-CIMS were the high mass-resolving power of the ToF mass analyzer and the capability of simultaneous measurement of the full mass range (typically up to 300 m/z) of product ions. Using hydronium ion based reagent ions, we demonstrated that the ID-ToF-CIMS can unambiguously measure ammonia (NH3) at 18.03 m/z, methyl amine (CH3NH2) at 32.05 m/z, formic acid (HCOOH) at 47.01 m/z and acetone (CH3COCH3) at 59.05 m/z. Calibrations were performed with both compressed commercial standard gases and permeation tubes and the results showed that the instrument detection limit can reach pptv level for 1 s average time or less. The ID-ToF-CIMS was also field tested in a mobile laboratory on the campus of Nanjing University of Information Science & Technology (NUIST). The preliminary results will be discussed.

  14. 14 CFR 398.7 - Timing of flights.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Timing of flights. 398.7 Section 398.7... STATEMENTS GUIDELINES FOR INDIVIDUAL DETERMINATIONS OF BASIC ESSENTIAL AIR SERVICE § 398.7 Timing of flights. To qualify as essential air service, flights must depart at reasonable times, considering the needs...

  15. 14 CFR 398.7 - Timing of flights.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Timing of flights. 398.7 Section 398.7... STATEMENTS GUIDELINES FOR INDIVIDUAL DETERMINATIONS OF BASIC ESSENTIAL AIR SERVICE § 398.7 Timing of flights. To qualify as essential air service, flights must depart at reasonable times, considering the needs...

  16. 14 CFR 398.7 - Timing of flights.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Timing of flights. 398.7 Section 398.7... STATEMENTS GUIDELINES FOR INDIVIDUAL DETERMINATIONS OF BASIC ESSENTIAL AIR SERVICE § 398.7 Timing of flights. To qualify as essential air service, flights must depart at reasonable times, considering the needs...

  17. 14 CFR 398.7 - Timing of flights.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Timing of flights. 398.7 Section 398.7... STATEMENTS GUIDELINES FOR INDIVIDUAL DETERMINATIONS OF BASIC ESSENTIAL AIR SERVICE § 398.7 Timing of flights. To qualify as essential air service, flights must depart at reasonable times, considering the needs...

  18. Real-time 3D video utilizing a compressed sensing time-of-flight single-pixel camera

    NASA Astrophysics Data System (ADS)

    Edgar, Matthew P.; Sun, Ming-Jie; Gibson, Graham M.; Spalding, Gabriel C.; Phillips, David B.; Padgett, Miles J.

    2016-09-01

    Time-of-flight 3D imaging is an important tool for applications such as remote sensing, machine vision and autonomous navigation. Conventional time-of-flight three-dimensional imaging systems that utilize a raster scanned laser to measure the range of each pixel in the scene sequentially, inherently have acquisition times that scale directly with the resolution. Here we show a modified time-of-flight 3D camera employing structured illumination, which uses a visible camera to enable a novel compressed sensing technique, minimising the acquisition time as well as providing a high-resolution reflectivity map for image overlay. Furthermore, a quantitative assessment of the 3D imaging performance is provided.

  19. Nanometer scale elemental analysis in the helium ion microscope using time of flight spectrometry.

    PubMed

    Klingner, N; Heller, R; Hlawacek, G; von Borany, J; Notte, J; Huang, J; Facsko, S

    2016-03-01

    Time of flight backscattering spectrometry (ToF-BS) was successfully implemented in a helium ion microscope (HIM). Its integration introduces the ability to perform laterally resolved elemental analysis as well as elemental depth profiling on the nm scale. A lateral resolution of ≤54nm and a time resolution of Δt≤17ns(Δt/t≤5.4%) are achieved. By using the energy of the backscattered particles for contrast generation, we introduce a new imaging method to the HIM allowing direct elemental mapping as well as local spectrometry. In addition laterally resolved time of flight secondary ion mass spectrometry (ToF-SIMS) can be performed with the same setup. Time of flight is implemented by pulsing the primary ion beam. This is achieved in a cost effective and minimal invasive way that does not influence the high resolution capabilities of the microscope when operating in standard secondary electron (SE) imaging mode. This technique can thus be easily adapted to existing devices. The particular implementation of ToF-BS and ToF-SIMS techniques are described, results are presented and advantages, difficulties and limitations of this new techniques are discussed.

  20. Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping

    NASA Astrophysics Data System (ADS)

    Dickel, Timo; Plaß, Wolfgang R.; Lippert, Wayne; Lang, Johannes; Yavor, Mikhail I.; Geissel, Hans; Scheidenberger, Christoph

    2017-03-01

    A novel method for (ultra-)high-resolution spatial mass separation in time-of-flight mass spectrometers is presented. Ions are injected into a time-of-flight analyzer from a radio frequency (rf) trap, dispersed in time-of-flight according to their mass-to-charge ratios and then re-trapped dynamically in the same rf trap. This re-trapping technique is highly mass-selective and after sufficiently long flight times can provide even isobaric separation. A theoretical treatment of the method is presented and the conditions for optimum performance of the method are derived. The method has been implemented in a multiple-reflection time-of-flight mass spectrometer and mass separation powers (FWHM) in excess of 70,000, and re-trapping efficiencies of up to 35% have been obtained for the protonated molecular ion of caffeine. The isobars glutamine and lysine (relative mass difference of 1/4000) have been separated after a flight time of 0.2 ms only. Higher mass separation powers can be achieved using longer flight times. The method will have important applications, including isobar separation in nuclear physics and (ultra-)high-resolution precursor ion selection in multiple-stage tandem mass spectrometry.

  1. Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping

    NASA Astrophysics Data System (ADS)

    Dickel, Timo; Plaß, Wolfgang R.; Lippert, Wayne; Lang, Johannes; Yavor, Mikhail I.; Geissel, Hans; Scheidenberger, Christoph

    2017-06-01

    A novel method for (ultra-)high-resolution spatial mass separation in time-of-flight mass spectrometers is presented. Ions are injected into a time-of-flight analyzer from a radio frequency (rf) trap, dispersed in time-of-flight according to their mass-to-charge ratios and then re-trapped dynamically in the same rf trap. This re-trapping technique is highly mass-selective and after sufficiently long flight times can provide even isobaric separation. A theoretical treatment of the method is presented and the conditions for optimum performance of the method are derived. The method has been implemented in a multiple-reflection time-of-flight mass spectrometer and mass separation powers (FWHM) in excess of 70,000, and re-trapping efficiencies of up to 35% have been obtained for the protonated molecular ion of caffeine. The isobars glutamine and lysine (relative mass difference of 1/4000) have been separated after a flight time of 0.2 ms only. Higher mass separation powers can be achieved using longer flight times. The method will have important applications, including isobar separation in nuclear physics and (ultra-)high-resolution precursor ion selection in multiple-stage tandem mass spectrometry. [Figure not available: see fulltext.

  2. Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping.

    PubMed

    Dickel, Timo; Plaß, Wolfgang R; Lippert, Wayne; Lang, Johannes; Yavor, Mikhail I; Geissel, Hans; Scheidenberger, Christoph

    2017-03-15

    A novel method for (ultra-)high-resolution spatial mass separation in time-of-flight mass spectrometers is presented. Ions are injected into a time-of-flight analyzer from a radio frequency (rf) trap, dispersed in time-of-flight according to their mass-to-charge ratios and then re-trapped dynamically in the same rf trap. This re-trapping technique is highly mass-selective and after sufficiently long flight times can provide even isobaric separation. A theoretical treatment of the method is presented and the conditions for optimum performance of the method are derived. The method has been implemented in a multiple-reflection time-of-flight mass spectrometer and mass separation powers (FWHM) in excess of 70,000, and re-trapping efficiencies of up to 35% have been obtained for the protonated molecular ion of caffeine. The isobars glutamine and lysine (relative mass difference of 1/4000) have been separated after a flight time of 0.2 ms only. Higher mass separation powers can be achieved using longer flight times. The method will have important applications, including isobar separation in nuclear physics and (ultra-)high-resolution precursor ion selection in multiple-stage tandem mass spectrometry. Graphical Abstract ᅟ.

  3. Characterization of Organic Nitrogen in the Atmosphere Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ge, X.; Sun, Y.; Chen, M.; Zhang, Q.

    2015-12-01

    Despite extensive efforts on characterizing organic nitrogen (ON) compounds in atmospheric aerosols and aqueous droplets, knowledge of ON chemistry is still limited, mainly due to its chemical complexity and lack of highly time-resolved measurements. This work is aimed at optimizing the method of using Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) to characterize ON compounds in atmospheric aerosols. Seventy-five pure nitrogen-containing organic compounds covering a variety of functional groups were analyzed with the HR-AMS. Our results show that ON compounds commonly produce NHx+, NOx+, which are usually attributed to inorganic N species such as ammonium and nitrate, and CH2N+ at m/z = 28, which is rarely quantified in ambient aerosol due to large interference from N2+ in the air signal. As a result, using the nitrogen-to-carbon (N/C) calibration factor proposed by Aiken et al. (2008) on average leads to ~ 20% underestimation of N/C in ambient organic aerosol. A new calibration factor of 0.79 is proposed for determining the average N/C in organics. The relative ionization efficiencies (RIEs) of different ON species, on average, are found to be consistent with the default RIE value (1.4) for the total organics. The AMS mass spectral features of various types of ON species (amines, amides, amino acids, etc.) are examined and used for characterizing ON composition in ambient aerosols. Our results indicate that submicron organic aerosol measured during wintertime in Fresno, CA contains significant amounts of amino-compounds whereas more diversified ON species, including N-containing aromatic heterocycle (e.g., imidazoles), are observed in fog waters collected simultaneously. Our findings have important implications for understanding atmospheric ON behaviors via the widespread HR-AMS measurements of ambient aerosols and droplets.

  4. Analytical properties of time-of-flight PET data

    NASA Astrophysics Data System (ADS)

    Cho, Sanghee; Ahn, Sangtae; Li, Quanzheng; Leahy, Richard M.

    2008-06-01

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

  5. Analytical Properties of Time-of-Flight PET Data

    PubMed Central

    Cho, Sanghee; Ahn, Sangtae; Li, Quanzheng; Leahy, Richard M.

    2015-01-01

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the “bow-tie” property of the 2D Radon transform to the time of flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data. PMID:18460746

  6. Analytical properties of time-of-flight PET data.

    PubMed

    Cho, Sanghee; Ahn, Sangtae; Li, Quanzheng; Leahy, Richard M

    2008-06-07

    We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

  7. Time-of-flight spectroscopy for medical applications

    NASA Astrophysics Data System (ADS)

    Plucinski, Jerzy

    2004-08-01

    The paper presents benefits of optical time-of-flight spectroscopy for medical applications. It also presents the principles of measurement and describes how the basic optical properties of tissue can be estimated from measured data. The potential of time-of-flight spectroscopy is demonstrated, based on measurements conducted for highly scattering materials, such as paper samples, technological liquids from paper mills and aqueous milk solutions. Picosecond semiconductor pulse lasers and fast light detectors (a streak camera and an avalanche photodiode working in Geiger mode) were used. Obtained results show that it is possible to construct a new type of optic fiber sensors for medical applications. The chief advantage of the sensors is their ability to perform measurements in difficult to reach places (e.g. inside human body). Moreover, it is expected that fiber optic sensors based on time-of-flight spectroscopy will significantly reduce the costs of medical diagnosis.

  8. Cut-off insensitive guidance with variable time of flight

    NASA Astrophysics Data System (ADS)

    White, John E.

    A guidance strategy is proposed for reducing target miss produced by performance uncertainty in the final stage of ballistic missile systems that do not have thrust termination or other velocity control capability. The approach taken here is to turn the thrusting missile onto a null range direction such that performance uncertainty contributions to target miss are reduced. The guidance algorithm proposed here does not constrain time-of-flight. Since time-of-flight normally varies with thrusting flight along a null range direction, the result is a guidance solution that does not change rapidly near the end of the motor burn. This guidance procedure is a variation of an iterative Lambert guidance scheme that can be used with ballistic missile systems that lack a velocity control capability to provide a position constraint with a nearly constant burn attitude by allowing a variable time-of-flight.

  9. Time-of-Flight Mass Measurements of Neutron Rich Nuclides

    NASA Astrophysics Data System (ADS)

    Estrade, A.; Matos, M.; Amthor, A. M.; Becerril, A.; Elliot, T.; Lorusso, G.; Rogers, A.; Schatz, H.; Bazin, D.; Gade, A.; Portillo, M.; Stolz, A.; Galaviz, D.; Pereira, J.; Shapira, D.; Smith, E.; Wallace, M.

    2008-10-01

    Nuclear masses of neutron rich isotopes in the region of Z ˜ 20-30 have been measured using the time-of-flight technique at the National Superconducting Cyclotron Laboratory (NSCL). The masses of 5 isotopes have been measured for the first time, and the precision of several other masses has been improved. The time-of-flight technique has shown the potential to access nuclear masses very far from stability when applied at radioactive beam facilities like the NSCL. Such measurements are important for understanding nuclear structure far from the valley of β-stability, and provide valuable information for astrophysical model calculations of processes involving very unstable nuclides.

  10. Proposal for Cherenkov Time of Flight Technique with Picosecond Resolution

    SciTech Connect

    S. Majewski; A. Margaryan; L. Tang

    2005-08-05

    A new particle identification device for Jlab 12 GeV program is proposed. It is based on the measurement of time information obtained by means of a new photon detector and time measuring concept. The expected time measurement precision for the Cherenkov time-of-flight detector is about or less than 10 picosecond for Cherenkov radiators with lengths less than 50 cm.

  11. Time-of-flight imaging of invisibility cloaks.

    PubMed

    Halimeh, Jad C; Wegener, Martin

    2012-01-02

    As invisibility cloaking has recently become experimental reality, it is interesting to explore ways to reveal remaining imperfections. In essence, the idea of most invisibility cloaks is to recover the optical path lengths without an object (to be made invisible) by a suitable arrangement around that object. Optical path length is proportional to the time of flight of a light ray or to the optical phase accumulated by a light wave. Thus, time-of-flight images provide a direct and intuitive tool for probing imperfections. Indeed, recent phase-sensitive experiments on the carpet cloak have already made early steps in this direction. In the macroscopic world, time-of-flight images could be measured directly by light detection and ranging (LIDAR). Here, we show calculated time-of-flight images of the conformal Gaussian carpet cloak, the conformal grating cloak, the cylindrical free-space cloak, and of the invisible sphere. All results are obtained by using a ray-velocity equation of motion derived from Fermat's principle.

  12. Rocket-borne time-of-flight mass spectrometry

    NASA Technical Reports Server (NTRS)

    Reiter, R. F.

    1976-01-01

    Theoretical and numerical analyses are made of planar, cylindrical and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km.

  13. 14 CFR 398.7 - Timing of flights.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Timing of flights. 398.7 Section 398.7 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) POLICY... reasonableness of the time in view of the purpose for which the local passengers are traveling. If travel...

  14. High-Resolution Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Marshall, Alan G.; Hendrickson, Christopher L.

    2008-07-01

    Over the past decade, mass spectrometry has been revolutionized by access to instruments of increasingly high mass-resolving power. For small molecules up to ˜400 Da (e.g., drugs, metabolites, and various natural organic mixtures ranging from foods to petroleum), it is possible to determine elemental compositions (CcHhNnOoSsPp…) of thousands of chemical components simultaneously from accurate mass measurements (the same can be done up to 1000 Da if additional information is included). At higher mass, it becomes possible to identify proteins (including posttranslational modifications) from proteolytic peptides, as well as lipids, glycoconjugates, and other biological components. At even higher mass (˜100,000 Da or higher), it is possible to characterize posttranslational modifications of intact proteins and to map the binding surfaces of large biomolecule complexes. Here we review the principles and techniques of the highest-resolution analytical mass spectrometers (time-of-flight and Fourier transform ion cyclotron resonance and orbitrap mass analyzers) and describe some representative high-resolution applications.

  15. Asymmetric band flipping for time-of-flight neutron diffraction data

    SciTech Connect

    Whitfield, Pamela S.; Coelho, Alan A.

    2016-08-24

    Charge flipping with powder diffraction data is known to produce a result more reliably with high-resolution data,i.e.visible reflections at smalldspacings. This data are readily accessible with the neutron time-of-flight technique but the assumption that negative scattering density is nonphysical is no longer valid where elements with negative scattering lengths are present. The concept of band flipping was introduced in the literature, where a negative threshold is used in addition to a positive threshold during the flipping. But, it was not tested with experimental data at the time. Finallly, band flipping has been implemented inTOPAStogether with the band modification of low-density elimination and tested with experimental powder and Laue single-crystal neutron data.

  16. Delayed bunching for multi-reflection time-of-flight mass separation

    SciTech Connect

    Rosenbusch, M.; Marx, G.; Schweikhard, L.; Wienholtz, F.; Chauveau, P.; Delahaye, P.

    2015-06-29

    Many experiments are handicapped when the ion sources do not only deliver the ions of interest but also contaminations, i.e., unwanted ions of similar mass. In the recent years, multi-reflection time-of-flight mass separation has become a promising method to isolate the ions of interest from the contaminants, in particular for measurements with low-energy short-lived nuclides. To further improve the performance of multi-reflection mass separators with respect to the limitations by space-charge effects, the simultaneously trapped ions are spatially widely distributed in the apparatus. Thus, the ions can propagate with reduced Coulomb interactions until, finally, they are bunched by a change in the trapping conditions for high-resolution mass separation. Proof-of-principle measurements are presented.

  17. Application of time-of-flight secondary ion mass spectrometry to automobile paint analysis.

    PubMed

    Lee, Y; Han, S; Yoon, J H; Kim, Y M; Shon, S K; Park, S W

    2001-06-01

    Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides a method of elemental analysis that can distinguish among automotive paint samples of the same or nearly the same color. TOF-SIMS survey spectra were employed to determine the relative abundances of elements in the surface layers of the paint chips. The depth profile of paint samples permitted the analysis of small paint chips, the reproducible results for specific elements, and the identification of each car paint. Seventy-three samples of blue, red, white, and silver automobile paints from the major manufacturers in Korea were investigated using high resolution TOF-SIMS technique. It was found that paints of the same color produced by different manufacturers could be distinguished by this technique. TOF-SIMS is a reliable, nondestructive, and small area analyzing method for characterization of the elemental composition of automotive paint chips.

  18. Asymmetric band flipping for time-of-flight neutron diffraction data

    SciTech Connect

    Whitfield, Pamela S.; Coelho, Alan A.

    2016-08-24

    Charge flipping with powder diffraction data is known to produce a result more reliably with high-resolution data,i.e.visible reflections at smalldspacings. This data are readily accessible with the neutron time-of-flight technique but the assumption that negative scattering density is nonphysical is no longer valid where elements with negative scattering lengths are present. The concept of band flipping was introduced in the literature, where a negative threshold is used in addition to a positive threshold during the flipping. But, it was not tested with experimental data at the time. Finallly, band flipping has been implemented inTOPAStogether with the band modification of low-density elimination and tested with experimental powder and Laue single-crystal neutron data.

  19. Asymmetric band flipping for time-of-flight neutron diffraction data

    DOE PAGES

    Whitfield, Pamela S.; Coelho, Alan A.

    2016-08-24

    Charge flipping with powder diffraction data is known to produce a result more reliably with high-resolution data,i.e.visible reflections at smalldspacings. This data are readily accessible with the neutron time-of-flight technique but the assumption that negative scattering density is nonphysical is no longer valid where elements with negative scattering lengths are present. The concept of band flipping was introduced in the literature, where a negative threshold is used in addition to a positive threshold during the flipping. But, it was not tested with experimental data at the time. Finallly, band flipping has been implemented inTOPAStogether with the band modification of low-densitymore » elimination and tested with experimental powder and Laue single-crystal neutron data.« less

  20. Development of a 10 picosecond time-of-flight Counter

    SciTech Connect

    Brandt, Andrew G

    2010-03-18

    This Advanced Detector Research proposal presented a plan to develop an extremely fast time-of-flight detector for measuring the arrival time of beam protons scattered at small angles in high energy hadron colliders, such as the Large Hadron Collider (LHC). The proposed detectors employ a gas or quartz Cerenkov radiator which produce light when a proton passes through them, coupled to a micro-channel plate photomultiplier tube (MCP-PMT) that converts the light to an electrical pulse. The very small jitter of the pulse time provided by the MCP-PMT, combined with downstream electronics that accurately measure the pulse time results in a time-of-flight measurement of unprecedented accuracy. This ADR proposal was extremely successful, culminating in the development of a 10 ps resolution time-of-flight system, about an order of magnitude better than any time-of-flight system previously deployed at a collider experiment. The primary areas of advance were the usage of new radiator geometries providing fast detector signals, using multiple measurements to obtain a superior system resolution, and development of an electronics readout system tuned to maintain the excellent timing afforded by the detector. Test beam and laser tests have improved the knowledge of MCP-PMT’s and enabled the evaluation of the new detector concepts. In addition to being a generally useful detector concept, these fast timing detectors are a major component of proposed upgrades to the LHC ATLAS and CMS detectors, and if deployed could significantly enhance the discovery potential of these detectors, including contributions to the measurement of the properties of the Higgs Boson. In addition to the potential for furthering fundamental understanding of nature, the knowledge gained on MCP-PMT’s could be useful in developing improved versions of these devices which have promise in diverse fields such as biological and medical imaging.

  1. Time-of-flight direct recoil ion scattering spectrometer

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.; Lamich, George J.

    1994-01-01

    A time of flight direct recoil and ion scattering spectrometer beam line (10). The beam line (10) includes an ion source (12) which injects ions into pulse deflection regions (14) and (16) separated by a drift space (18). A final optics stage includes an ion lens and deflection plate assembly (22). The ion pulse length and pulse interval are determined by computerized adjustment of the timing between the voltage pulses applied to the pulsed deflection regions (14) and (16).

  2. Time-of-flight direct recoil ion scattering spectrometer

    DOEpatents

    Krauss, A.R.; Gruen, D.M.; Lamich, G.J.

    1994-09-13

    A time-of-flight direct recoil and ion scattering spectrometer beam line is disclosed. The beam line includes an ion source which injects ions into pulse deflection regions and separated by a drift space. A final optics stage includes an ion lens and deflection plate assembly. The ion pulse length and pulse interval are determined by computerized adjustment of the timing between the voltage pulses applied to the pulsed deflection regions. 23 figs.

  3. A Segmented Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Iga, I.; Rao, M. V. V. S.

    1995-01-01

    The present paper describes the design of a time-of-flight mass spectrometer (TOFMS) in which the single flight tube of a conventional TOFMS has been replaced by several cylindrical electrostatic lenses in tandem. By a judicious choice of voltages on these lenses, an improved TOFMS has been realized which has a superior mass and energy resolution, shorter flight lengths, excellent signal-to-noise ratio and less stringent requirements on the bias voltages.

  4. KELVIN rare gas time-of-flight program

    SciTech Connect

    Vernon, M.

    1981-03-01

    The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed.

  5. Continuous time of flight measurements in a Lissajous configuration.

    PubMed

    Dobos, G; Hárs, G

    2017-01-01

    Short pulses used by traditional time-of-flight mass spectrometers limit their duty cycle, pose space-charge issues, and require high speed detectors and electronics. The motivation behind the invention of continuous time of flight mass spectrometers was to mitigate these problems, by increasing the number of ions reaching the detector and eliminating the need for fast data acquisition systems. The most crucial components of these spectrometers are their modulators: they determine both the maximal modulation frequency and the modulation depth. Through these parameters they limit the achievable mass resolution and signal-to-noise ratio. In this paper, a new kind of setup is presented which modulates the beam by deflecting it in two perpendicular directions and collects ions on a position sensitive detector. Such an Lissajous time of flight spectrometer achieves modulation without the use of slits or apertures, making it possible for all ions to reach the detector, thereby increasing the transmission and signal-to-noise ratio. In this paper, we provide the mathematical description of the system, discuss its properties, and present a practical demonstration of the principle.

  6. Continuous time of flight measurements in a Lissajous configuration

    NASA Astrophysics Data System (ADS)

    Dobos, G.; Hárs, G.

    2017-01-01

    Short pulses used by traditional time-of-flight mass spectrometers limit their duty cycle, pose space-charge issues, and require high speed detectors and electronics. The motivation behind the invention of continuous time of flight mass spectrometers was to mitigate these problems, by increasing the number of ions reaching the detector and eliminating the need for fast data acquisition systems. The most crucial components of these spectrometers are their modulators: they determine both the maximal modulation frequency and the modulation depth. Through these parameters they limit the achievable mass resolution and signal-to-noise ratio. In this paper, a new kind of setup is presented which modulates the beam by deflecting it in two perpendicular directions and collects ions on a position sensitive detector. Such an Lissajous time of flight spectrometer achieves modulation without the use of slits or apertures, making it possible for all ions to reach the detector, thereby increasing the transmission and signal-to-noise ratio. In this paper, we provide the mathematical description of the system, discuss its properties, and present a practical demonstration of the principle.

  7. Time of flight imaging through scattering environments (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Le, Toan H.; Breitbach, Eric C.; Jackson, Jonathan A.; Velten, Andreas

    2017-02-01

    Light scattering is a primary obstacle to imaging in many environments. On small scales in biomedical microscopy and diffuse tomography scenarios scattering is caused by tissue. On larger scales scattering from dust and fog provide challenges to vision systems for self driving cars and naval remote imaging systems. We are developing scale models for scattering environments and investigation methods for improved imaging particularly using time of flight transient information. With the emergence of Single Photon Avalanche Diode detectors and fast semiconductor lasers, illumination and capture on picosecond timescales are becoming possible in inexpensive, compact, and robust devices. This opens up opportunities for new computational imaging techniques that make use of photon time of flight. Time of flight or range information is used in remote imaging scenarios in gated viewing and in biomedical imaging in time resolved diffuse tomography. In addition spatial filtering is popular in biomedical scenarios with structured illumination and confocal microscopy. We are presenting a combination analytical, computational, and experimental models that allow us develop and test imaging methods across scattering scenarios and scales. This framework will be used for proof of concept experiments to evaluate new computational imaging methods.

  8. High Resolution Computed Tomography

    DTIC Science & Technology

    1992-07-31

    samples. 14. SUBJECTTERMS 15. NUMBER OF PAGES 38 High Resolution, Microfocus , Characterization, X - Ray , Micrography, Computed Tomography (CT), Failure...high resolutions (50 g.tm feature sensitivity) when a small field of view (50 mm) is used [11]. Specially designed detectors and a microfocus X - ray ...Wright Laboratories. Feldkamp [14] at Ford used a microfocus X - ray source and an X - ray image intensifier to develop a system capable of 20 g.m

  9. An introduction to quadrupole-time-of-flight mass spectrometry.

    PubMed

    Chernushevich, I V; Loboda, A V; Thomson, B A

    2001-08-01

    A brief introduction is presented to the basic principles and application of a quadrupole-time-of-flight (TOF) tandem mass spectrometer. The main features of reflecting TOF instruments with orthogonal injection of ions are discussed. Their operation and performance are compared with those of triple quadrupoles with electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) TOF mass spectrometers. Examples and recommendations are provided for all major operational modes: mass spectrometry (MS) and tandem MS (MS/MS), precursor ion scans and studies of non-covalent complexes. Basic algorithms for liquid chromatography/MS/MS automation are discussed and illustrated by two applications.

  10. Continuous time-of-flight ion mass spectrometer

    DOEpatents

    Funsten, Herbert O.; Feldman, William C.

    2004-10-19

    A continuous time-of-flight mass spectrometer having an evacuated enclosure with means for generating an electric field located in the evacuated enclosure and means for injecting a sample material into the electric field. A source of continuous ionizing radiation injects ionizing radiation into the electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between arrival of a secondary electron out of said ionized atoms or molecules at a first predetermined location and arrival of a sample ion out of said ionized atoms or molecules at a second predetermined location.

  11. Time-of-Flight Tip-Clearance Measurements

    NASA Technical Reports Server (NTRS)

    Dhadwal, H. S.; Kurkov, A. P.; Janetzke, D. C.

    1999-01-01

    In this paper a time-of-flight probe system incorporating the two integrated fiber optic probes which are tilted equally relative to the probe holder centerline, is applied for the first time to measure the tip clearance of an advanced fan prototype. Tip clearance is largely independent of the signal amplitude and it relies on timing measurement. This work exposes optical effects associated with the fan blade stagger angle that were absent during the original spin-rig experiment on the zero stagger rotor. Individual blade tip clearances were measured with accuracy of +/- 127-mm (+/- 0.005-in). Probe features are discussed and improvements to the design are suggested.

  12. Compensated time of flight telescope for spaceborne cosmic ray measurements

    NASA Technical Reports Server (NTRS)

    Rothermel, H.

    1977-01-01

    A large area time-of-flight telescope has been studied for future application in space-borne cosmic ray experiments. A new compensation technique for propagation delays inside the scintillators has been applied, which is operative in two perpendicular directions. This technique, superior to conventional one-dimensional compensations, allows high rejection probability for upward moving single particles at very short counter distances. Besides mechanical advantages a short counter distance is desirable because it permits a large field of view for the detector. A measurement of light transit times in scintillators is presented and based on it, directionality for shower events is discussed.

  13. Miniature Focusing Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Kanik, Isik; Srivastava, Santosh

    2005-01-01

    An improved miniature time-of-flight mass spectrometer has been developed in a continuing effort to minimize the sizes, weights, power demands, and costs of mass spectrometers for such diverse applications as measurement of concentrations of pollutants in the atmosphere, detecting poisonous gases in mines, and analyzing exhaust gases of automobiles. Advantageous characteristics of this mass spectrometer include the following: It is simple and rugged. Relative to prior mass spectrometers, it is inexpensive to build. There is no need for precise alignment of its components. Its mass range is practically unlimited Relative to prior mass spectrometers, it offers high sensitivity (ability to measure relative concentrations as small as parts per billion). Its resolution is one dalton (one atomic mass unit). An entire mass spectrum is recorded in a single pulse. (In a conventional mass spectrometer, a spectrum is recorded mass by mass.) The data-acquisition process takes only seconds. It is a lightweight, low-power, portable instrument. Although time-of-flight mass spectrometers (TOF-MSs) have been miniaturized previously, their performances have not been completely satisfactory. An inherent adverse effect of miniaturization of a TOF-MS is a loss of resolution caused by reduction of the length of its flight tube. In the present improved TOF-MS, the adverse effect of shortening the flight tube is counteracted by (1) using charged-particle optics to constrain ion trajectories to the flight-tube axis while (2) reducing ion velocities to increase ion flight times. In the present improved TOF-MS, a stream of gas is generated by use of a hypodermic needle. The stream of gas is crossed by an energy-selected, pulsed beam of electrons (see Figure 1). The ions generated by impingement of the electrons on the gas atoms are then focused by three cylindrical electrostatic lenses, which constitute a segmented flight tube. After traveling along the flight tube, the ions enter a charged

  14. Time-of-flight diffractometer with multiple pulse overlap - an example for the application of modern tools for instrument design

    SciTech Connect

    Stuhr, U.; Bauer, G.S.; Wagner, W.

    1997-09-01

    A Time-of-Flight Diffractometer with high pulse rates, allowing multiple frame overlap, is a completely novel design of an instrument dedicated for high resolution strain-field mapping. We elaborated a detailed concept of this instrument applying analytical calculations and Monte Carlo computer simulations. Having established the instrument concept, the computer simulations will now be extended to optimize the total performance of the instrument. To illustrate the necessity and possibilities of applying modem tools for instrument design, we describe, as an example, the different steps towards the development of the detailed design of this instrument, which we intend to build at the Swiss spallation. source SINQ in the near future.

  15. Characterizing particulate matter emissions from vehicles: chassis-dynamometer tests using a High-Resolution Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Collier, S.; Zhang, Q.; Forestieri, S.; Kleeman, M.; Cappa, C. D.; Kuwayama, T.

    2012-12-01

    During September of 2011 a suite of real-time instruments was used to sample vehicle emissions at the California Air Resources Board Haagen-Schmidt facility in El Monte, CA. A representative fleet of 8 spark ignition gasoline vehicles, a diesel passenger vehicle, a gasoline direct-injection vehicle and an ultra-low emissions vehicle were tested on a chassis dynamometer. The emissions were sampled into the facility's standard CVS tunnel and diluted to atmospherically relevant levels (5-30 μg/m3) while controlling other factors such as relative humidity or background black carbon particulate loading concentrations. An Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-MS) was among the real-time instruments used and sampled vehicle emissions at 10 second time resolution in order to characterize the non-refractory organic and inorganic particulate matter (PM). PM composition and concentration were tracked throughout the cold start driving cycle which included periods of fast acceleration and high velocity cruise control, meant to recreate typical commuter driving behavior. Variations in inorganic and organic PM composition for a given vehicle throughout the driving cycle as well as for various vehicles with differing emissions loading were characterized. Differences in PM composition for a given vehicle whose emissions are being exposed to differing experimental conditions such as varying relative humidity will also be reported. In conjunction with measurements from a Multi Wavelength Photoacoustic Black Carbon Spectrometer (MWPA-BC) and real-time gas measurements from the CARB facility, we determine the real-time emission ratios of primary organic aerosols (POA) with respect to BC and common combustion gas phase pollutants and compared to different vehicle driving conditions. The results of these tests offer the vehicle emissions community a first time glimpse at the real-time behavior of vehicle PM emissions for a variety of conditions and

  16. Time-of-flight mass spectrometry: Introduction to the basics.

    PubMed

    Boesl, Ulrich

    2017-01-01

    The intention of this tutorial is to introduce into the basic concepts of time-of-flight mass spectrometry, beginning with the most simple single-stage ion source with linear field-free drift region and continuing with two-stage ion sources combined with field-free drift regions and ion reflectors-the so-called reflectrons. Basic formulas are presented and discussed with the focus on understanding the physical relations of geometric and electric parameters, initial distribution of ionic parameters, ion flight times, and ion flight time incertitude. This tutorial is aimed to help the applicant to identify sources of flight time broadening which limit good mass resolution and sources of ion losses which limit sensitivity; it is aimed to stimulate creativity for new experimental approaches by discussing a choice of instrumental options and to encourage those who toy with the idea to build an own time-of-flight mass spectrometer. Large parts of mathematics are shifted into a separate chapter in order not to overburden the text with too many mathematical deviations. Rather, thumb-rule formulas are supplied for first estimations of geometry and potentials when designing a home-built instrument, planning experiments, or searching for sources of flight time broadening. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:86-109, 2017.

  17. Inductively Coupled Plasma Zoom-Time-of-Flight Mass Spectrometry.

    PubMed

    Dennis, Elise A; Ray, Steven J; Enke, Christie G; Hieftje, Gary M

    2016-03-01

    A zoom-time-of-flight mass spectrometer has been coupled to an inductively coupled plasma (ICP) ionization source. Zoom-time-of-flight mass spectrometry (zoom-TOFMS) combines two complementary types of velocity-based mass separation. Specifically, zoom-TOFMS alternates between conventional, constant-energy acceleration (CEA) TOFMS and energy-focused, constant-momentum acceleration (CMA) (zoom) TOFMS. The CMA mode provides a mass-resolution enhancement of 1.5-1.7× over CEA-TOFMS in the current, 35-cm ICP-zoom-TOFMS instrument geometry. The maximum resolving power (full-width at half-maximum) for the ICP-zoom-TOFMS instrument is 1200 for CEA-TOFMS and 1900 for CMA-TOFMS. The CMA mode yields detection limits of between 0.02 and 0.8 ppt, depending upon the repetition rate and integration time-compared with single ppt detection limits for CEA-TOFMS. Isotope-ratio precision is shot-noise limited at approximately 0.2% relative-standard deviation (RSD) for both CEA- and CMA-TOFMS at a 10 kHz repetition rate and an integration time of 3-5 min. When the repetition rate is increased to 43.5 kHz for CMA, the shot-noise limited, zoom-mode isotope-ratio precision is improved to 0.09% RSD for the same integration time.

  18. TITAN's multiple-reflection time-of-flight isobar separator

    NASA Astrophysics Data System (ADS)

    Reiter, Moritz Pascal; Titan Collaboration

    2016-09-01

    At the ISAC facility located at TRIUMF exotic nuclei are produced by the ISOL method. Exotic nuclei are separated by a magnetic separator and transported to TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). TITAN is a system of multiple ion traps for high precision mass measurements and in-trap decay spectroscopy. Although ISAC can deliver some of the highest yields for even many of the most exotic species many measurements suffer from a strong isobaric background. This background often prevents the high precision measurement of the species of interest. To overcome this limitation an additional isobar separator based on the Multiple-Reflection Time-Of-Flight Mass Spectrometry (MR-TOF-MS) technique has been developed for TITAN. Mass selection is achieved using dynamic re-trapping of the species of interest after a time-of-flight analysis in an electrostatic isochronous reflector system. Additionally the MR-TOF-MS will, on its own, enable mass measurements of very short-lived nuclides that are weakly produced. Being able to measure all isobars of a given mass number at the same time the MR-TOF-MS can be used for beam diagnostics or determination of beam compositions. Results from the offline commissioning showing mass resolving power and separation power will be presented.

  19. Development of Soft Ionization for Particulate Organic Detection with the Aerodyne Aerosol Mass Spectrometer

    SciTech Connect

    Trimborn, A; Williams, L R; Jayne, J T; Worsnop, D R

    2008-06-19

    During this DOE SBIR Phase II project, we have successfully developed several soft ionization techniques, i.e., ionization schemes which involve less fragmentation of the ions, for use with the Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS). Vacuum ultraviolet single photon ionization was demonstrated in the laboratory and deployed in field campaigns. Vacuum ultraviolet single photon ionization allows better identification of organic species in aerosol particles as shown in laboratory experiments on single component particles, and in field measurements on complex multi-component particles. Dissociative electron attachment with lower energy electrons (less than 30 eV) was demonstrated in the measurement of particulate organics in chamber experiments in Switzerland, and is now a routine approach with AMS systems configured for bipolar, negative ion detection. This technique is particularly powerful for detection of acidic and other highly oxygenated secondary organic aerosol (SOA) chemical functionality. Low energy electron ionization (10 to 12 eV) is also a softer ionization approach routinely available to AMS users. Finally, Lithium ion attachment has been shown to be sensitive to more alkyl-like chemical functionality in SOA. Results from Mexico City are particularly exciting in observing changes in SOA molecular composition under different photochemical/meteorological conditions. More recent results detecting biomass burns at the Montana fire lab have demonstrated quantitative and selective detection of levoglucosan. These soft ionization techniques provide the ToF-AMS with better capability for identifying organic species in ambient atmospheric aerosol particles. This, in turn, will allow more detailed study of the sources, transformations and fate of organic-containing aerosol.

  20. High-resolution headlamp

    NASA Astrophysics Data System (ADS)

    Gut, Carsten; Cristea, Iulia; Neumann, Cornelius

    2016-04-01

    The following article shall describe how human vision by night can be influenced. At first, front lighting systems that are already available on the market will be described, followed by their analysis with respect to the positive effects on traffic safety. Furthermore, how traffic safety by night can be increased since the introduction of high resolution headlamps shall be discussed.

  1. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

    SciTech Connect

    Andersen, T.; Jensen, R.; Christensen, M. K.; Chorkendorff, I.; Pedersen, T.; Hansen, O.

    2012-07-15

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/{Delta}m > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH{sub 3}.

  2. High energy collisions on tandem time-of-flight mass spectrometers†

    PubMed Central

    Cotter, Robert J.

    2013-01-01

    Long before the introduction of matrix-assisted laser desorption (MALDI), electrospray ionization (ESI), Orbitraps and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were nonetheless some clear advantages for sectors over their low collision energy counterparts. Time-of-flight mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective we recount our own journey to produce high performance time-of-flights and tandems, describing the basic theory, problems and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging and the characterization of microorganisms. PMID:23519928

  3. High-performance multiple-reflection time-of-flight mass spectrometers for research with exotic nuclei and for analytical mass spectrometry

    NASA Astrophysics Data System (ADS)

    Plaß, Wolfgang R.; Dickel, Timo; Ayet San Andres, Samuel; Ebert, Jens; Greiner, Florian; Hornung, Christine; Jesch, Christian; Lang, Johannes; Lippert, Wayne; Majoros, Tamas; Short, Devin; Geissel, Hans; Haettner, Emma; Reiter, Moritz P.; Rink, Ann-Kathrin; Scheidenberger, Christoph; Yavor, Mikhail I.

    2015-11-01

    A class of multiple-reflection time-of-flight mass spectrometers (MR-TOF-MSs) has been developed for research with exotic nuclei at present and future accelerator facilities such as GSI and FAIR (Darmstadt), and TRIUMF (Vancouver). They can perform highly accurate mass measurements of exotic nuclei, serve as high-resolution, high-capacity mass separators and be employed as diagnostics devices to monitor the production, separation and manipulation of beams of exotic nuclei. In addition, a mobile high-resolution MR-TOF-MS has been developed for in situ applications in analytical mass spectrometry ranging from environmental research to medicine. Recently, the MR-TOF-MS for GSI and FAIR has been further developed. A novel RF quadrupole-based ion beam switchyard has been developed that allows merging and splitting of ion beams as well as transport of ions into different directions. It efficiently connects a test and reference ion source and an auxiliary detector to the system. Due to an increase in the kinetic energy of the ions in the time-of-flight analyzer of the MR-TOF-MS, a given mass resolving power is now achieved in less than half the time-of-flight. Conversely, depending on the time-of-flight, the mass resolving power has been increased by a factor of more than two.

  4. The time-of-flight wall for the HADES spectrometer

    SciTech Connect

    Agodi, C.; Bassi, A.; Bassini, R.

    1998-06-01

    In the framework of the HADES (High Acceptance DiElectron Spectrometer) collaboration the authors are developing the Time Of Flight (TOF) wall subdetector. In order to efficiently select events with e{sup +}e{sup {minus}} pairs produced in the nuclear matter, the TOF wall must be able to resolve electrons from pions up to 0.5 GeV/c and from protons up to 2 GeV/c. Because the short flight path of about 2m requires a 100--150 ps time resolution, the authors are building a granular system made of scintillator rods readout on both ends by means of photomultipliers, capable of such performance.

  5. Avalanche photodiode based time-of-flight mass spectrometry.

    PubMed

    Ogasawara, Keiichi; Livi, Stefano A; Desai, Mihir I; Ebert, Robert W; McComas, David J; Walther, Brandon C

    2015-08-01

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1-40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  6. Avalanche photodiode based time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ogasawara, Keiichi; Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C.

    2015-08-01

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1-40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  7. Tests and calibration of NIF neutron time of flight detectors.

    PubMed

    Ali, Z A; Glebov, V Yu; Cruz, M; Duffy, T; Stoeckl, C; Roberts, S; Sangster, T C; Tommasini, R; Throop, A; Moran, M; Dauffy, L; Horsefield, C

    2008-10-01

    The National Ignition Facility (NIF) neutron time of flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD(*) implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 1x10(9) to 2x10(19). The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory. Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detector tests and calibration will be presented.

  8. Linear electronic field time-of-flight ion mass spectrometers

    DOEpatents

    Funsten, Herbert O.

    2010-08-24

    Time-of-flight mass spectrometer comprising a first drift region and a second drift region enclosed within an evacuation chamber; a means of introducing an analyte of interest into the first drift region; a pulsed ionization source which produces molecular ions from said analyte of interest; a first foil positioned between the first drift region and the second drift region, which dissociates said molecular ions into constituent atomic ions and emits secondary electrons; an electrode which produces secondary electrons upon contact with a constituent atomic ion in second drift region; a stop detector comprising a first ion detection region and a second ion detection region; and a timing means connected to the pulsed ionization source, to the first ion detection region, and to the second ion detection region.

  9. Avalanche photodiode based time-of-flight mass spectrometry

    SciTech Connect

    Ogasawara, Keiichi Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C.

    2015-08-15

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1−40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  10. Accurate Fiber Length Measurement Using Time-of-Flight Technique

    NASA Astrophysics Data System (ADS)

    Terra, Osama; Hussein, Hatem

    2016-06-01

    Fiber artifacts of very well-measured length are required for the calibration of optical time domain reflectometers (OTDR). In this paper accurate length measurement of different fiber lengths using the time-of-flight technique is performed. A setup is proposed to measure accurately lengths from 1 to 40 km at 1,550 and 1,310 nm using high-speed electro-optic modulator and photodetector. This setup offers traceability to the SI unit of time, the second (and hence to meter by definition), by locking the time interval counter to the Global Positioning System (GPS)-disciplined quartz oscillator. Additionally, the length of a recirculating loop artifact is measured and compared with the measurement made for the same fiber by the National Physical Laboratory of United Kingdom (NPL). Finally, a method is proposed to relatively correct the fiber refractive index to allow accurate fiber length measurement.

  11. Time-of-flight detector for heavy ion backscattering spectrometry

    SciTech Connect

    Knapp, J.A.; Banks, J.C.; Doyle, B.L.

    1994-04-01

    This report describes the results of a two-year laboratory directed research and development project to explore advanced concepts in Heavy Ion Backscattering Spectrometry (HIBS), undertaken with the goal of extending the sensitivity of this relatively new technique to levels unattainable by any other existing trace element surface analysis. Improvements in sensitivity are required for the application of HIBS to contamination control in the microelectronics industry. Tools with sensitivity approaching 10{sup 8} atoms/cm{sup 2} are expected to be essential for enabling advanced IC production by the year 2000. During the project the authors developed a new analysis chamber with channeling goniometer and a prototype time-of-flight detector with a demonstrated sensitivity of {approximately} 5 {times} 10{sup 8} atoms/cm{sup 2} for Au on Si and {approximately} 5 {times} 10{sup 10} for Fe, and sufficient mass resolution to separate contributions from Fe and Cu.

  12. Highly charged ion based time of flight emission microscope

    DOEpatents

    Barnes, Alan V.; Schenkel, Thomas; Hamza, Alex V.; Schneider, Dieter H.; Doyle, Barney

    2001-01-01

    A highly charged ion based time-of-flight emission microscope has been designed, which improves the surface sensitivity of static SIMS measurements because of the higher ionization probability of highly charged ions. Slow, highly charged ions are produced in an electron beam ion trap and are directed to the sample surface. The sputtered secondary ions and electrons pass through a specially designed objective lens to a microchannel plate detector. This new instrument permits high surface sensitivity (10.sup.10 atoms/cm.sup.2), high spatial resolution (100 nm), and chemical structural information due to the high molecular ion yields. The high secondary ion yield permits coincidence counting, which can be used to enhance determination of chemical and topological structure and to correlate specific molecular species.

  13. A time-of-flight line sensor: development and application

    NASA Astrophysics Data System (ADS)

    Kaufmann, Rolf; Lehmann, Michael; Schweizer, Matthias; Richter, Michael; Metzler, Peter; Lang, Graham; Oggier, Thierry; Blanc, Nicolas; Seitz, Peter; Gruener, Gabriel; Zbinden, Urs

    2004-09-01

    A new miniaturised 256 pixel silicon line sensor, which allows for the acquisition of depth-resolved images in real-time, is presented. It reliably and simultaneously delivers intensity data as well as distance information on the objects in the scene. The depth measurement is based on the time-of-flight (TOF) principle. The device allows the simultaneous measurement of the phase, offset and amplitude of a radio frequency modulated light field that is emitted by the system and reflected back by the camera surroundings, without requiring any mechanical scanning parts. The 3D line sensor will be used on a mobile robot platform to substitute the laser range scanners traditionally used for navigation in dynamic and/or unknown environments.

  14. The Time-of-Flight trigger at CDF

    SciTech Connect

    Bauer, G.; Mulhearn, M.J.; Paus, Ch.; Schieferdecker, P.; Tether, S.; Lewis, J.D.; Shaw, T.; Acosta, D.; Konigsberg, J.; Madorsky, A.; /Florida U.

    2006-05-01

    The Time-of-Flight (TOF) detector measures the arrival time and deposited energy of charged particles reaching scintillator bars surrounding the central tracking region of the CDF detector. Requiring high ionization in the TOF system provides a unique trigger capability, which has been used for a magnetic monopole search. Other uses, with smaller pulse height thresholds, include a high-multiplicity charged-particle trigger useful for QCD studies and a much improved cosmic ray trigger for calibrating other detector components. Although not designed as input to CDF's global Level 1 trigger, the TOF system has been easily adapted to this role by the addition of 24 cables, new firmware, and four custom TOF trigger boards (TOTRIBs). This article describes the TOF trigger.

  15. Inverse time-of-flight spectrometer for beam plasma research

    SciTech Connect

    Yushkov, Yu. G. Zolotukhin, D. B.; Tyunkov, A. V.; Oks, E. M.

    2014-08-15

    The paper describes the design and principle of operation of an inverse time-of-flight spectrometer for research in the plasma produced by an electron beam in the forevacuum pressure range (5–20 Pa). In the spectrometer, the deflecting plates as well as the drift tube and the primary ion beam measuring system are at high potential with respect to ground. This provides the possibility to measure the mass-charge constitution of the plasma created by a continuous electron beam with a current of up to 300 mA and electron energy of up to 20 keV at forevacuum pressures in the chamber placed at ground potential. Research results on the mass-charge state of the beam plasma are presented and analyzed.

  16. Chern numbers hiding in time-of-flight images

    SciTech Connect

    Zhao Erhai; Satija, Indubala I.; Bray-Ali, Noah; Williams, Carl J.; Spielman, I. B.

    2011-12-15

    We present a technique for detecting topological invariants--Chern numbers--from time-of-flight images of ultracold atoms. We show that the Chern numbers of integer quantum Hall states of lattice fermions leave their fingerprints in the atoms' momentum distribution. We analytically demonstrate that the number of local maxima in the momentum distribution is equal to the Chern number in two limiting cases, for large hopping anisotropy and in the continuum limit. In addition, our numerical simulations beyond these two limits show that these local maxima persist for a range of parameters. Thus, an everyday observable in cold atom experiments can serve as a useful tool to characterize and visualize quantum states with nontrivial topology.

  17. VCSELs as light source for time-of-flight sensors

    NASA Astrophysics Data System (ADS)

    Moench, Holger; Frey, Manuel; Grabherr, Martin; Gronenborn, Stephan; Gudde, Ralph; Kolb, Johanna; Miller, Michael; Weigl, Alexander

    2017-02-01

    VCSELs and VCSEL arrays are an ideal light source for time-of-flight based sensors. The narrow emission spectrum and the ability for short pulses make them superior to LEDs. Combined with fast photodiodes or special camera chips spatial 3D information can be obtained which is needed in diverse applications like camera autofocus, indoor navigation, 3Dobject recognition or even autonomously driving vehicles. VCSEL arrays are the way to tailor the output power. For pulse operation at low duty cycle average heat dissipation is no longer the upper limit to the operating point of VCSELs but over-pulsing becomes possible. Taking into account electrical boundary conditions and optimum conversion efficiency arrays can be designed for specific operating conditions. Measurements of arrays under short pulse operation are presented using a package with integrated driver.

  18. Time-of-flight Fourier Spectrometry with UCN

    NASA Astrophysics Data System (ADS)

    Kulin, G. V.; Frank, A. I.; Goryunov, S. V.; Geltenbort, P.; Jentschel, M.; Bushuev, V. A.; Lauss, B.; Schmidt-Wellenburg, Ph.; Panzarella, A.; Fuchs, Y.

    2016-09-01

    The report presents the first experience of using a time-of-flight Fourier spectrometer of ultracold neutrons (UCN). The description of the spectrometer design and first results of its testing are presented. The results of the first experiments show that the spectrometer may be used for obtaining UCN energy spectra in the energy range of 60÷200 neV with a resolution of about 5 neV. The application of TOF Fourier spectrometry technique allowed us to obtain the energy spectra from the diffraction of monochromatic ultracold neutrons on a moving grating. Lines of 0, +1 and +2 diffraction orders were simultaneously recorded, which had previously been impossible to be done by other methods. These results have made it possible to make a comparison with the recent theoretical calculations based on the dynamical theory of neutron diffraction on a moving phase grating.

  19. High resolution data acquisition

    DOEpatents

    Thornton, G.W.; Fuller, K.R.

    1993-04-06

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock, pulse train, and analog circuitry for generating a triangular wave synchronously with the pulse train (as seen in diagram on patent). The triangular wave has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter counts the clock pulse train during the interval to form a gross event interval time. A computer then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  20. High resolution data acquisition

    DOEpatents

    Thornton, Glenn W.; Fuller, Kenneth R.

    1993-01-01

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock (38) pulse train (37) and analog circuitry (44) for generating a triangular wave (46) synchronously with the pulse train (37). The triangular wave (46) has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter (18, 32) forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter (26) counts the clock pulse train (37) during the interval to form a gross event interval time. A computer (52) then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  1. Panoramic High Resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Freeman, K.; Bland-Hawthorn, J.

    2008-10-01

    Stellar populations in galaxies are vast repositories of fossil information. In recent years it has become possible to consider high resolution spectroscopic surveys of millions of stars. New high resolution multi-object spectrographs on 4-8m class telescopes (HERMES, WFMOS) will allow us for the first time to make large and detailed chemical abundance surveys of stars in the Galactic disk, bulge and halo, and apply the techniques of chemical tagging to recovering the fossil information left over from galaxy assembly. These instruments will have strong synergies with the GAIA astrometric satellite due to launch in 2011. The level of detail made possible by these future facilities will be necessary if we are to fully understand the physical processes involved in galaxy formation.

  2. High resolution data acquisition

    SciTech Connect

    Thornton, G.W.; Fuller, K.R.

    1992-12-31

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock pulse train and analog circuitry for generating a triangular wave synchronously with the pulse train. The triangular wave has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter counts the clock pulse train during the interval to form a gross event interval time. A computer then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  3. High-Resolution Autoradiography

    NASA Technical Reports Server (NTRS)

    Towe, George C; Gomberg, Henry J; Freemen, J W

    1955-01-01

    This investigation was made to adapt wet-process autoradiography to metallurgical samples to obtain high resolution of segregated radioactive elements in microstructures. Results are confined to development of the technique, which was perfected to a resolution of less than 10 microns. The radioactive samples included carbon-14 carburized iron and steel, nickel-63 electroplated samples, a powder product containing nickel-63, and tungsten-185 in N-155 alloy.

  4. Ultra high resolution tomography

    SciTech Connect

    Haddad, W.S.

    1994-11-15

    Recent work and results on ultra high resolution three dimensional imaging with soft x-rays will be presented. This work is aimed at determining microscopic three dimensional structure of biological and material specimens. Three dimensional reconstructed images of a microscopic test object will be presented; the reconstruction has a resolution on the order of 1000 A in all three dimensions. Preliminary work with biological samples will also be shown, and the experimental and numerical methods used will be discussed.

  5. Determination of aerosol ammonium using an aerodyne aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Toohey, D. W.; Worsnop, D. R.

    2003-04-01

    The chemical composition of fine aerosols is a significant issue both because it influences the chemical and radiative properties of the aerosols, which in turn impact the regional and global climate and human health, and because it is difficult to measure accurately. The Aerosol Mass Spectrometer (AMS) developed by Aerodyne Research measures both chemical composition and aerodynamic size of submicron aerosols quantitatively. However, the measurement of aerosol ammonium is more difficult than that of the other major inorganic species, nitrate and sulfate, because of interferences in the mass spectrum from air and water. This presentation will describe the successful procedure developed for dealing with these interferences and accurately determining the ammonium mass. In addition, the application of this procedure to aerosols from a range of ambient conditions will be demonstrated using data from several field studies.

  6. Saturn's rings - high resolution

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Voyager 2 obtained this high-resolution picture of Saturn's rings Aug. 22, when the spacecraft was 4 million kilometers (2.5 million miles) away. Evident here are the numerous 'spoke' features, in the B-ring; their very sharp, narrow appearance suggests short formation times. Scientists think electromagnetic forces are responsible in some way for these features, but no detailed theory has been worked out. Pictures such as this and analyses of Voyager 2's spoke movies may reveal more clues about the origins of these complex structures. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

  7. Video Guidance Sensor and Time-of-Flight Rangefinder

    NASA Technical Reports Server (NTRS)

    Bryan, Thomas; Howard, Richard; Bell, Joseph L.; Roe, Fred D.; Book, Michael L.

    2007-01-01

    A proposed video guidance sensor (VGS) would be based mostly on the hardware and software of a prior Advanced VGS (AVGS), with some additions to enable it to function as a time-of-flight rangefinder (in contradistinction to a triangulation or image-processing rangefinder). It would typically be used at distances of the order of 2 or 3 kilometers, where a typical target would appear in a video image as a single blob, making it possible to extract the direction to the target (but not the orientation of the target or the distance to the target) from a video image of light reflected from the target. As described in several previous NASA Tech Briefs articles, an AVGS system is an optoelectronic system that provides guidance for automated docking of two vehicles. In the original application, the two vehicles are spacecraft, but the basic principles of design and operation of the system are applicable to aircraft, robots, objects maneuvered by cranes, or other objects that may be required to be aligned and brought together automatically or under remote control. In a prior AVGS system of the type upon which the now-proposed VGS is largely based, the tracked vehicle is equipped with one or more passive targets that reflect light from one or more continuous-wave laser diode(s) on the tracking vehicle, a video camera on the tracking vehicle acquires images of the targets in the reflected laser light, the video images are digitized, and the image data are processed to obtain the direction to the target. The design concept of the proposed VGS does not call for any memory or processor hardware beyond that already present in the prior AVGS, but does call for some additional hardware and some additional software. It also calls for assignment of some additional tasks to two subsystems that are parts of the prior VGS: a field-programmable gate array (FPGA) that generates timing and control signals, and a digital signal processor (DSP) that processes the digitized video images. The

  8. Development of an ion time-of-flight spectrometer for neutron depth profiling

    NASA Astrophysics Data System (ADS)

    Cetiner, Mustafa Sacit

    signal. Without loss of generality, the secondary signal is obtained by the passage of the ion through a thin carbon foil, which produces ion-induced secondary electron emission (IISEE). The time-of-flight spectrometer physically acts as an ion/electron separator. The electrons that enter the active volume of the spectrometer are transported onto the microchannel plate detector to generate the secondary signal. The electron optics can be designed in variety of ways depending on the nature of the measurement and physical requirements. Two ion time-of-flight spectrometer designs are introduced: the parallel electric and magnetic (PEM) field spectrometer and the cross electric and magnetic (CEM) field spectrometer. The CEM field spectrometers have been extensively used in a wide range of applications where precise mass differentiation is required. The PEM field spectrometers have lately found interest in mass spectroscopy applications. The application of the PEM field spectrometer for energy measurements is a novel approach. The PEM field spectrometer used in the measurements employs axial electric and magnetic fields along the nominal direction of the incident ion. The secondary electrons are created by a thin carbon foil on the entrance disk and transported on the microchannel plate that faces the carbon foil. The initial angular distribution of the secondary electrons has virtually no effect on the transport time of the secondary electrons from the surface of the carbon foil to the electron microchannel plate detector. Therefore, the PEM field spectrometer can offer high-resolution energy measurement for relatively lower electric fields. The measurements with the PEM field spectrometer were made with the Tandem linear particle accelerator at the IBM T. J. Watson Research Center at Yorktown Heights, NY. The CEM field spectrometer developed for the thesis employs axial electric field along the nominal direction of the ion, and has perpendicular magnetic field. As the

  9. Laser Time-of-Flight Mass Spectrometry for Space

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, W. B.; Managadze, G. G.; McEntire, R. W.; Cheng, A. F.; Green, W. J.

    2000-01-01

    A miniature reflection time-of-flight mass spectrometer for in situ planetary surface analysis is described. The laser ablation mass spectrometer (LAMS) measures the regolith's elemental and isotopic composition without high-voltage source extraction or sample preparation. The compact size (< 2 x 10(exp 3) cubic cm) and low mass (approximately 2 kg) of LAMS, due to its fully coaxial design and two-stage reflectron, fall within the strict resource limitations of landed science missions to solar system bodies. A short-pulse laser focused to a spot with a diameter approximately 30-50 micrometers is used to obtain microscopic surface samples. Assisted by a microimager, LAMS can interactively select and analyze a range of compositional regions (with lateral motion) and with repeated pulses can access unweathered, subsurface materials. The mass resolution is calibrated to distinguish isotopic peaks at unit masses, and detection limits are on resolved to a few ppm. The design and calibration method of a prototype LAMS device is described, which include the development of preliminary relative sensitivity coefficients for major element bulk abundance measurements.

  10. Performance of the Tachyon Time-of-Flight PET Camera

    DOE PAGES

    Peng, Q.; Choong, W. -S.; Vu, C.; ...

    2015-01-23

    We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 ×25 mm2 side of 6.15 ×6.15 ×25 mm3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMAmore » NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- 20 ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. We find that the results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.« less

  11. Performance of the Tachyon Time-of-Flight PET Camera

    SciTech Connect

    Peng, Q.; Choong, W. -S.; Vu, C.; Huber, J. S.; Janecek, M.; Wilson, D.; Huesman, R. H.; Qi, Jinyi; Zhou, Jian; Moses, W. W.

    2015-01-23

    We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 ×25 mm2 side of 6.15 ×6.15 ×25 mm3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- 20 ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. We find that the results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.

  12. Performance of the Tachyon Time-of-Flight PET Camera

    PubMed Central

    Peng, Q.; Choong, W.-S.; Vu, C.; Huber, J. S.; Janecek, M.; Wilson, D.; Huesman, R. H.; Qi, Jinyi; Zhou, Jian; Moses, W. W.

    2015-01-01

    We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon’s detector module is optimized for timing by coupling the 6.15 × 25 mm2 side of 6.15 × 6.15 × 25 mm3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/− ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3. PMID:26594057

  13. Time-of-flight photoconductivity in polymer/graphene blends

    NASA Astrophysics Data System (ADS)

    Bratina, Gvido; Pavlica, Egon; Pathipati, Srinivasa Rao; Nawrocki, Robert; Penumala, Raveendra

    2015-03-01

    We have used time-of-flight (TOF) photoconductivity measurements to assess the electric charge transport parameters in thin layers of poly(3-hexyl thiophene-2,5-diyl) (P3HT) mixed with single and multiple-layer graphene nanoflakes. Thin layers were cast from a solution and two co-planar metal electrodes were deposited by vacuum evaporation on top. An electric field was set up between the electrodes A laser pulse was used to photogenerate charge carriers near the biased electrode, and time dependence of the photocurrent (I(t)) was measured at the opposite electrode. I(t) curves were confronted to I(t)s obtained by a Gaussian-disorder Monte Carlo simulations, adapted to thin-film geometry. The simulations included a position-dependent electric field between two coplanar electrodes, which importantly affects the charge carrier transport through the blend between the electrodes. Comparison between the simulated and measured I(t)s resulted in values for charge carrier mobility, average charge velocity and variation of charge velocity. Our results show that the hole mobility in blends is increased by more than an order of magnitude in comparison to the hole mobility of a neat layers of P3HT

  14. The diamond time of flight detector of the TOTEM experiment

    NASA Astrophysics Data System (ADS)

    Berretti, Mirko

    2017-02-01

    This contribution describes the design and the performance of a novel timing detector developed by the TOTEM Collaboration. The detector will be installed inside the TOTEM Roman Pots (RPs) and will measure the Time-Of-Flight (TOF) of the protons produced in the central diffractive (CD) interactions at the LHC. In particular, the measurement of the proton TOF allows the determination of the vertex longitudinal position where the protons are produced, thus allowing the protons association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal CVD (scCVD) diamond plates and it is designed in order to measure the protons TOF with 50 ps time resolution. To achieve this performance, a dedicated fast and low noise electronics for the signal amplification has been developed. Indeed, while diamond sensors have lower noise and faster signals than silicon sensors, the amount of charge released in the medium is lower. The digitization of the diamond signal is performed sampling the waveform at 10 GSa/s with the SAMPIC chip. The performance of the first TOF detector installed in the LHC in November 2015 will be reported. An overview of the clock distribution system and of the control system which interfaces the timing detectors to the experiment DAQ is finally given.

  15. Time-of-flight observation of electron swarm in methane

    SciTech Connect

    Hasegawa, H.; Date, H.; Yoshida, K.; Shimozuma, M.

    2009-06-01

    This paper reports on the evolution of an isolated electron swarm, which is experimentally observed as spatial distributions at every moment. This observation is assumed to directly correspond to the conventional time-of-flight theory. We have measured the spatial distribution of electrons using a double-shutter technique in the drift tube, where a shutter electrode to collect electrons can be slid along the field (E/N) direction in order to capture a relative electron number at a certain range of location. As a typical parameter defined by this spatial distribution, the center-of-mass drift velocity (W{sub r}) is determined for methane gas. The result is compared with the mean-arrival-time drift velocity (W{sub m}) defined from the arriving electron number at fixed positions. We have also performed a theoretical analysis in which a Fourier transformed Boltzmann equation is solved to deduce both of the drift velocities from a dispersion relationship. The difference between W{sub r} and W{sub m} at high E/Ns (above 200 Td) is clearly ascertained in the experimental and theoretical investigations, which is attributable to the occurrence of ionization events.

  16. Proposed STAR Time of Flight Readout Electronics and DAQ

    NASA Astrophysics Data System (ADS)

    Schambach, Joachim

    2006-04-01

    A novel Time-of-Flight (TOF) subsystem is under design for the STAR detector at RHIC. A total of 3840 Multi-gap Resistive Plate Chambers (MRPC) of 6 pads each are distributed over 120 trays. The total number of channels is 23040. Each TOF tray consists of 192 detector channels and three different types of electronic circuit cards, called "TINO", "TDIG", and "TCPU", listed in order of the data flow. Every 30 trays send their data to a "THUB" card that interfaces to the STAR trigger and transmits the data over a fiber to a fiber receiver which is part of STAR DAQ. The TINO contains the analog front end electronics based on a custom IC called NINO. The output of TINO is passed to the TDIG, where the data are digitized (using the CERN HPTDC ASIC). The TCPU formats and buffers the digital detector information. This formatted data is passed to THUB, which transmits it over an optical fiber to a data receiver in the STAR DAQ room. The architecture of this readout chain and DAQ will be described, and first results from prototypes of the component boards will be discussed.

  17. Polarisation analysis on the LET time-of-flight spectrometer

    NASA Astrophysics Data System (ADS)

    Nilsen, G. J.; Košata, J.; Devonport, M.; Galsworthy, P.; Bewley, R. I.; Voneshen, D. J.; Dalgliesh, R.; Stewart, J. R.

    2017-06-01

    We present a design for implementing uniaxial polarisation analysis on the LET cold neutron time-of-flight spectrometer, installed on the second target station at ISIS. The polarised neutron beam is to be produced by a transmission-based supermirror polariser with the polarising mirrors arranged in a “double-V” formation. This will be followed by a Mezei-type precession coil spin flipper, selected for its small spatial requirements, as well as a permanent magnet guide field to transport the beam polarisation to the sample position. The sample area will contain a set of holding field coils, whose purpose is to produce a highly homogenous magnetic field for the wide-angle 3He analyser cell. To facilitate fast cell changes and reduce the risk of cell failure, we intend to separate the cell and cryostat from the vacuum of the sample tank by installing both in a vessel at atmospheric pressure. When the instrument upgrade is complete, the performance of LET is expected to be commensurate with existing and planned polarised cold neutron spectrometers at other sources. Finally, we discuss the implications of performing uniaxial polarisation analysis only, and identify quasi-elastic neutron scattering (QENS) on ionic conducting materials as an interesting area to apply the technique.

  18. Update on time-of-flight PET imaging

    PubMed Central

    Surti, Suleman

    2015-01-01

    Time-of-flight (TOF) PET was initially introduced in the early days of PET. TOF PET scanners developed in the 1980s had limited sensitivity and spatial resolution, operated in 2D mode with septa, and used analytic image reconstruction methods. Current generation of TOF PET scanners have the highest sensitivity and spatial resolution ever achieved in commercial whole-body PET, operate in fully-3D mode, and use iterative reconstruction with full system modeling. Previously, it was shown that TOF provides a gain in image signal-to-noise-ratio (SNR) that is proportional to the square root of the object size divided by the system timing resolution. With oncologic studies being the primary application of PET, more recent work has shown that in modern TOF PET scanners there is an improved trade-off between lesion contrast, image noise, and total imaging time, leading to a combination of improved lesion detectability, reduced scan time or injected dose, and more accurate and precise lesion uptake measurement. The benefit of TOF PET is also higher for heavier patients, which leads to a more uniform clinical performance over all patient sizes. PMID:25525181

  19. Performance of the Tachyon Time-of-Flight PET Camera.

    PubMed

    Peng, Q; Choong, W-S; Vu, C; Huber, J S; Janecek, M; Wilson, D; Huesman, R H; Qi, Jinyi; Zhou, Jian; Moses, W W

    2015-02-01

    We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 × 25 mm(2) side of 6.15 × 6.15 × 25 mm(3) LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.

  20. Studies of Electronic Stopping Powers Using Time of Flight Spectrometry

    SciTech Connect

    Zhang, Yanwen; Weber, William J.

    2004-06-01

    Determination of electronic stopping powers using Time of Flight (ToF) spectrometry have been demonstrated by measuring energy loss of He, O, and Al particles based on a ToF Elastic Recoil Detection Analysis (ERDA) set-up. In transmission geometry, the energy loss of the particles in self-supported stopping foils of C, Si and SiC is measured over a continuous range of energies using the ToF spectrometer. This study emphasizes the difference of the stopping power determination with and without dependence on the Si detector calibration over a wide energy range. By calibrating the Si detector for each channel over the measured energy region, the improved approach eliminates much of the error associated with pulsed height defects and measurement uncertainties of less than 4% are achieved. Stopping powers from this study are compared with limited experimental data from the literature and SRIM (The Stopping and Range of Ions in Matter) 2000 and 2003 predictions. In general, the predicted values are in reasonable agreement with the experimental data, and an improved accuracy of SRIM 2003 over SRIM 2000 can be observed in some cases. Furthermore, Braggs rule is valid in SiC for O and Al over the energy region studied.

  1. Proton Transfer Time-of-Flight Mass Spectrometer

    SciTech Connect

    Watson, Thomas B

    2016-03-01

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

  2. Benchmarking time-of-flight based depth measurement techniques

    NASA Astrophysics Data System (ADS)

    Süss, Andreas; Rochus, Veronique; Rosmeulen, Maarten; Rottenberg, Xavier

    2016-03-01

    In the last decade significant progress has been made on optical non-contact time-of-flight (ToF) based ranging techniques. Direct implementations based on time-correlated single photon counting (TCSPC-dToF), coincidence detection (CD-TCSPC-dToF) as well as multiple indirect realizations based on e.g. single-photon synchronous detection (SPSD-iToF), continuous-wave modulation (CW-iToF) or pulse modulation (PM-iToF) have been presented. All those modulation/demodulation techniques can be employed in scanning (scanning LIDAR) as well as non-scanning (Flash-LIDAR) schemes. Many parameters impact key performance metrics such as depth measurement precision or angular resolution. Unfortunately, publications or datasheets rarely quote all relevant parameters. Thus, benchmarking between different approaches based on published metrics is cumbersome. The authors believe that such a benchmark would have to be founded on modeling in order to ensure fair comparison. This work presents an overview over the most common ToF based depth measurement approaches, how these can be modeled and how they compare.

  3. Chern Numbers Hiding in Time of Flight Images

    NASA Astrophysics Data System (ADS)

    Satija, Indubala; Zhao, Erhai; Ghosh, Parag; Bray-Ali, Noah

    2011-03-01

    Since the experimental realization of synthetic magnetic fields in neural ultracold atoms, transport measurement such as quantized Hall conductivity remains an open challenge. Here we propose a novel and feasible scheme to measure the topological invariants, namely the chern numbers, in the time of flight images. We study both the commensurate and the incommensurate flux, with the later being the main focus here. The central concept underlying our proposal is the mapping between the chern numbers and the size of the dimerized states that emerge when the two-dimensional hopping is tuned to the highly anisotropic limit. In a uncoupled double quantum Hall system exhibiting time reversal invariance, only odd-sized dimer correlation functions are non-zero and hence encode quantized spin current. Finally, we illustrate that inspite of highly fragmented spectrum, a finite set of chern numbers are meaningful. Our results are supported by direct numerical computation of transverse conductivity. NBA acknowledges support from a National Research Council postdoctoral research associateship.

  4. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    SciTech Connect

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; Bredeweg, T.; Jandel, M.; Jorgenson, H. J.; Laptev, A.; Rusev, G.; Shields, D. W.; White, M.; Blakeley, R. E.; Mader, D. M.; Hecht, A. A.

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flight times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.

  5. Fragmentation study of aminoalcohol-diterpenoid alkaloids by electrospray ionization time-of-flight mass spectrometry.

    PubMed

    Liu, Xiuxiu; Tang, Minghai; Wang, Lu; Chao, Ruobing

    2016-01-15

    Aminoalcohol-diterpenoid alkaloids were found to be a group of cardioactive substances in the lateral roots of Aconitum carmichaeli Debx. Studies on the fragmentation behaviors and features of these alkaloids in mass spectrometry would be important for their structural identification and in vivo metabolic research, which has not received much attention thus far. In this study, the fragmentation behaviors of 14 aminoalcohol-diterpenoid alkaloids were investigated by utilizing high-resolution time-of-flight tandem mass spectrometry. By analysis of the obtained MS(2) data, we summarized the fragmentation features of the corresponding alkaloids under different collision energy. The dissociation of functional groups from the skeleton was observed as the main fragmentation way in electrospray ionization (ESI) mode. The order of fragmentation sites was C1/C3 > C16 > C15 > C6 > N, with loss of one or more CH3OH, H2O, C2H4 (substituent on N atom) or CO (at C15 ) groups. The first systematic investigations on the fragmentation of aminoalcohol-diterpenoid alkaloids are described in this paper, setting the stage for an in-depth identification and study of the corresponding components in complex systems. Copyright © 2015 John Wiley & Sons, Ltd.

  6. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    DOE PAGES

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; ...

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flightmore » times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.« less

  7. Combining endoscopic ultrasound with Time-Of-Flight PET: The EndoTOFPET-US Project

    NASA Astrophysics Data System (ADS)

    Frisch, Benjamin

    2013-12-01

    The EndoTOFPET-US collaboration develops a multimodal imaging technique for endoscopic exams of the pancreas or the prostate. It combines the benefits of high resolution metabolic imaging with Time-Of-Flight Positron Emission Tomography (TOF PET) and anatomical imaging with ultrasound (US). EndoTOFPET-US consists of a PET head extension for a commercial US endoscope and a PET plate outside the body in coincidence with the head. The high level of miniaturization and integration creates challenges in fields such as scintillating crystals, ultra-fast photo-detection, highly integrated electronics, system integration and image reconstruction. Amongst the developments, fast scintillators as well as fast and compact digital SiPMs with single SPAD readout are used to obtain the best coincidence time resolution (CTR). Highly integrated ASICs and DAQ electronics contribute to the timing performances of EndoTOFPET. In view of the targeted resolution of around 1 mm in the reconstructed image, we present a prototype detector system with a CTR better than 240 ps FWHM. We discuss the challenges in simulating such a system and introduce reconstruction algorithms based on graphics processing units (GPU).

  8. Ambient Observations of Organic Nitrogen Compounds in Submicrometer Aerosols in New York Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Ge, X.; Xu, J.; Sun, Y.; Zhang, Q.

    2015-12-01

    Organic nitrogen (ON) compounds, which include amines, nitriles, organic nitrates, amides, and N-containing aromatic heterocycles, are an important class of compounds ubiquitously detected in atmospheric particles and fog and cloud droplets. Previous studies indicate that these compounds can make up a significant fraction (20-80%) of the total nitrogen (N) content in atmospheric condensed phases and play important roles in new particle formation and growth and affecting the optical and hygroscopicity of aerosols. In this study, we report the observation of ON compounds in submicrometer particles (PM1) at two locations in New York based on measurements using Aerodyne high-resolution time-of-flight mass spectrometer (HR-ToF-AMS). One study was conducted as part of the US Department of Energy funded Aerosol Lifecyle - Intensive Operation Period (ALC-IOP) campaign at Brookhaven National Lab (BNL, 40.871˚N, 72.89˚W) in summer, 2011 and the other was conducted at the Queen's College (QC) in New York City (NYC) in summer, 2009. We observed a notable amount of N-containing organic fragment ions, CxHyNp+ and CxHyOzNp+, in the AMS spectra of organic aerosols at both locations and found that they were mainly associated with amino functional groups. Compared with results from lab experiments, the C3H8N+ at m/z = 58 was primarily attributed to trimethylamine. In addition, a significant amount of organonitrates was observed at BNL. Positive matrix factorization (PMF) analysis of the high resolution mass spectra (HRMS) of organic aerosols identified a unique nitrogen-enriched OA (NOA) factor with elevated nitrogen-to-carbon (N/C) at both BNL and QC. Analysis of the size distributions, volatility profiles, and correlations with external tracer indicates that acid-base reactions of amino compounds with sulfate and acidic gas were mainly responsible for the formation of amine salts. Photochemical production was also observed to play a role in the formation of NOA. Bivariate polar

  9. High resolution ultrasonic densitometer

    SciTech Connect

    Dress, W.B.

    1983-01-01

    The velocity of torsional stress pulses in an ultrasonic waveguide of non-circular cross section is affected by the temperature and density of the surrounding medium. Measurement of the transit times of acoustic echoes from the ends of a sensor section are interpreted as level, density, and temperature of the fluid environment surrounding that section. This paper examines methods of making these measurements to obtain high resolution, temperature-corrected absolute and relative density and level determinations of the fluid. Possible applications include on-line process monitoring, a hand-held density probe for battery charge state indication, and precise inventory control for such diverse fluids as uranium salt solutions in accountability storage and gasoline in service station storage tanks.

  10. High resolution hypernuclear spectroscopy

    SciTech Connect

    F. Garibaldi

    2005-02-01

    Hypernuclear spectroscopy provides fundamental information for understanding the effective ?-Nucleon interaction. Jefferson Laboratory experiment E94-107 was designed to perform high resolution hypernuclear spectroscopy by electroproduction of strangeness in four 1p-shell nuclei: 12C, 9Be, 16O, and 7Li. The first part of the experiment on 12C and 9Be has been performed in January and April-May 2004 in Hall A at Jefferson Lab. Significant modifications were made to the standard Hall A apparatus for this challenging experiment: two septum magnets and a RICH detector have been added to get reasonable counting rates and excellent particle identification, as required for the experiment. A description of the apparatus and the preliminary analysis results are presented here.

  11. Recent developments in time-of-flight PET.

    PubMed

    Vandenberghe, S; Mikhaylova, E; D'Hoe, E; Mollet, P; Karp, J S

    2016-12-01

    While the first time-of-flight (TOF)-positron emission tomography (PET) systems were already built in the early 1980s, limited clinical studies were acquired on these scanners. PET was still a research tool, and the available TOF-PET systems were experimental. Due to a combination of low stopping power and limited spatial resolution (caused by limited light output of the scintillators), these systems could not compete with bismuth germanate (BGO)-based PET scanners. Developments on TOF system were limited for about a decade but started again around 2000. The combination of fast photomultipliers, scintillators with high density, modern electronics, and faster computing power for image reconstruction have made it possible to introduce this principle in clinical TOF-PET systems. This paper reviews recent developments in system design, image reconstruction, corrections, and the potential in new applications for TOF-PET. After explaining the basic principles of time-of-flight, the difficulties in detector technology and electronics to obtain a good and stable timing resolution are shortly explained. The available clinical systems and prototypes under development are described in detail. The development of this type of PET scanner also requires modified image reconstruction with accurate modeling and correction methods. The additional dimension introduced by the time difference motivates a shift from sinogram- to listmode-based reconstruction. This reconstruction is however rather slow and therefore rebinning techniques specific for TOF data have been proposed. The main motivation for TOF-PET remains the large potential for image quality improvement and more accurate quantification for a given number of counts. The gain is related to the ratio of object size and spatial extent of the TOF kernel and is therefore particularly relevant for heavy patients, where image quality degrades significantly due to increased attenuation (low counts) and high scatter fractions. The

  12. Sensors for Using Times of Flight to Measure Flow Velocities

    NASA Technical Reports Server (NTRS)

    Fralick, Gutave; Wrbanek, John D.; Hwang, Danny; Turso, James

    2006-01-01

    Thin-film sensors for measuring flow velocities in terms of times of flight are undergoing development. These sensors are very small and can be mounted flush with surfaces of airfoils, ducts, and other objects along which one might need to measure flows. Alternatively or in addition, these sensors can be mounted on small struts protruding from such surfaces for acquiring velocity measurements at various distances from the surfaces for the purpose of obtaining boundary-layer flow-velocity profiles. These sensors are related to, but not the same as, hot-wire anemometers. Each sensor includes a thin-film, electrically conductive loop, along which an electric current is made to flow to heat the loop to a temperature above that of the surrounding fluid. Instantaneous voltage fluctuations in segments of the loop are measured by means of electrical taps placed at intervals along the loop. These voltage fluctuations are caused by local fluctuations in electrical resistance that are, in turn, caused by local temperature fluctuations that are, in turn, caused by fluctuations in flow-induced cooling and, hence, in flow velocity. The differential voltage as a function of time, measured at each pair of taps, is subjected to cross-correlation processing with the corresponding quantities measured at other pairs of taps at different locations on the loop. The cross-correlations yield the times taken by elements of fluid to travel between the pairs of taps. Then the component of velocity along the line between any two pairs of taps is calculated simply as the distance between the pairs of taps divided by the travel time. Unlike in the case of hot-wire anemometers, there is no need to obtain calibration data on voltage fluctuations versus velocity fluctuations because, at least in principle, the correlation times are independent of the calibration data.

  13. Optimal rebinning of time-of-flight PET data.

    PubMed

    Ahn, Sangtae; Cho, Sanghee; Li, Quanzheng; Lin, Yanguang; Leahy, Richard M

    2011-10-01

    Time-of-flight (TOF) positron emission tomography (PET) scanners offer the potential for significantly improved signal-to-noise ratio (SNR) and lesion detectability in clinical PET. However, fully 3D TOF PET image reconstruction is a challenging task due to the huge data size. One solution to this problem is to rebin TOF data into a lower dimensional format. We have recently developed Fourier rebinning methods for mapping TOF data into non-TOF formats that retain substantial SNR advantages relative to sinograms acquired without TOF information. However, mappings for rebinning into non-TOF formats are not unique and optimization of rebinning methods has not been widely investigated. In this paper we address the question of optimal rebinning in order to make full use of TOF information. We focus on FORET-3D, which approximately rebins 3D TOF data into 3D non-TOF sinogram formats without requiring a Fourier transform in the axial direction. We optimize the weighting for FORET-3D to minimize the variance, resulting in H(2)-weighted FORET-3D, which turns out to be the best linear unbiased estimator (BLUE) under reasonable approximations and furthermore the uniformly minimum variance unbiased (UMVU) estimator under Gaussian noise assumptions. This implies that any information loss due to optimal rebinning is as a result only of the approximations used in deriving the rebinning equation and developing the optimal weighting. We demonstrate using simulated and real phantom TOF data that the optimal rebinning method achieves variance reduction and contrast recovery improvement compared to nonoptimized rebinning weightings. In our preliminary study using a simplified simulation setup, the performance of the optimal rebinning method was comparable to that of fully 3D TOF MAP. © 2011 IEEE

  14. LVGEMS Time-of-Flight Mass Spectrometry on Satellites

    NASA Technical Reports Server (NTRS)

    Herrero, Federico

    2013-01-01

    NASA fs investigations of the upper atmosphere and ionosphere require measurements of composition of the neutral air and ions. NASA is able to undertake these observations, but the instruments currently in use have their limitations. NASA has extended the scope of its research in the atmosphere and now requires more measurements covering more of the atmosphere. Out of this need, NASA developed multipoint measurements using miniaturized satellites, also called nanosatellites (e.g., CubeSats), that require a new generation of spectrometers that can fit into a 4 4 in. (.10 10 cm) cross-section in the upgraded satellites. Overall, the new mass spectrometer required for the new depth of atmospheric research must fulfill a new level of low-voltage/low-power requirements, smaller size, and less risk of magnetic contamination. The Low-Voltage Gated Electrostatic Mass Spectrometer (LVGEMS) was developed to fulfill these requirements. The LVGEMS offers a new spectrometer that eliminates magnetic field issues associated with magnetic sector mass spectrometers, reduces power, and is about 1/10 the size of previous instruments. LVGEMS employs the time of flight (TOF) technique in the GEMS mass spectrometer previously developed. However, like any TOF mass spectrometer, GEMS requires a rectangular waveform of large voltage amplitude, exceeding 100 V -- that means that the voltage applied to one of the GEMS electrodes has to change from 0 to 100 V in a time of only a few nanoseconds. Such electronic speed requires more power than can be provided in a CubeSat. In the LVGEMS, the amplitude of the rectangular waveform is reduced to about 1 V, compatible with digital electronics supplies and requiring little power.

  15. Electronics for a Picosecond Time-of-flight Measurement

    SciTech Connect

    Brandt, Andrew Gerhart; Rijssenbeek, Michael

    2014-11-03

    TITLE: Electronics for a Picosecond Time-of-flight Measurement ABSTRACT: Time-of-flight (TOF) detectors have historically been used as part of the particle identification capability of multi-purpose particle physics detectors. An accurate time measurement, combined with a momentum measurement based on the curvature of the track in a magnetic field, is often sufficient to determine the particle's mass, and thus its identity. Such detectors typically have measured the particle flight time extremely precisely, with an uncertainty of one hundred trillionths of a second (also referred to as 100 picoseconds). To put this in perspective it would be like counting all the people on the Earth and getting it right within 1 person! Another use of TOFs is to measure the vertex of the event, which is the location along the beam line where the incoming particles (typically protons) collide. This vertex positon is a well measured quantity for events where the protons collide “head on” as the outgoing particles produced when you blast the proton apart can be used to trace back to a vertex point from which they originated. More frequently the protons just strike a glancing blow and remain intact—in this case they are nearly parallel to the beam and you cannot tell their vertex without this ability to precisely measure the time of flight of the protons. Occasionally both happen in the same event, that is, a central system and two protons are produced. But are they from the same collision, or just a boring background where more than one collision in the same bunch crossing conspire to fake the signal of interest? That’s where the timing of the protons comes into play. The main idea is to measure the time it takes for the two protons to reach TOF detectors positioned equidistant from the center of the main detector. If the vertex is displaced to one side than that detector will measure a shorter time while the other side detector will measure a correspondingly longer time

  16. High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.

    1999-01-01

    This report summarizes the accomplishments of the High Resolution Doppler Imager (HRDI) on UARS spacecraft during the period 4/l/96 - 3/31/99. During this period, HRDI operation, data processing, and data analysis continued, and there was a high level of vitality in the HRDI project. The HRDI has been collecting data from the stratosphere, mesosphere, and lower thermosphere since instrument activation on October 1, 1991. The HRDI team has stressed three areas since operations commenced: 1) operation of the instrument in a manner which maximizes the quality and versatility of the collected data; 2) algorithm development and validation to produce a high-quality data product; and 3) scientific studies, primarily of the dynamics of the middle atmosphere. There has been no significant degradation in the HRDI instrument since operations began nearly 8 years ago. HRDI operations are fairly routine, although we have continued to look for ways to improve the quality of the scientific product, either by improving existing modes, or by designing new ones. The HRDI instrument has been programmed to collect data for new scientific studies, such as measurements of fluorescence from plants, measuring cloud top heights, and lower atmosphere H2O.

  17. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data

    PubMed Central

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L.; Dronskowski, Richard

    2015-01-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages. PMID:26664340

  18. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data.

    PubMed

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2015-12-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages.

  19. Development of a Metastable Atom Bombardment (MAB) Source for Penning Ionization Time-of-flight Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Robinson, C. B.; Kimmel, J. R.; David, D.; Jayne, J. T.; Trimborn, A.; Worsnop, D. R.; Jimenez, J. L.

    2009-12-01

    The Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS) utilizes thermal vaporization followed by electron ionization (EI) to convert aerosol components to gas-phase ions. The method enables quantification of chemical classes, but the extensive fragmentation caused by EI limits the specificity of both chemical analysis and source identification by factor analysis. To better identify the molecular components of aerosols, we have constructed a metastable atom bombardment (MAB) ionization source that can be interfaced to standard ToF-AMS hardware. A beam of metastable rare gas atoms is produced by a low-voltage DC discharge and focused toward the vaporization plume, yielding Penning Ionization of the analyte molecules. By changing gases, the excited energies of the metastables can be adjusted between 20.61 eV (He) and 9.92 eV (Kr). Source parameters, including pressures, current, geometry, and materials, were optimized for He, Ar, and Kr. Instrument sensitivity and induced fragmentation was characterized for each using lab-generated oleic acid particles. The demonstrated sensitivities are 0.1% of EI (3% of the SNR of EI in the V-mode, comparable to the Q-AMS SNR), which is sufficient for ambient monitoring. A metastable flux of 2.6e14 sr-1sec-1 has been achieved. The MAB-AMS has been deployed to the FLAME-3 campaign at the USDA Fire Sciences Laboratory in Missoula, MT, and used to sample smoke from open burning of different biomass samples. Preliminary results from FLAME-3 will be presented.

  20. Top-down proteomics with a quadrupole time-of-flight mass spectrometer and collision-induced dissociation.

    PubMed

    Armirotti, Andrea; Benatti, Umberto; Damonte, Gianluca

    2009-03-01

    With slight modifications of the instrumental parameters, we demonstrate that satisfactory top-down data can be obtained with collision-induced dissociation (CID) tandem mass spectrometry on a quadrupole time-of-flight (qTOF) instrument not originally designed for this purpose. Protein identification is achieved with both N- and C-terminal sequence tags and BLAST database searches. The accurate mass measurement of multiply charged fragment ions (mostly y and b-type) supplements the limited set of cleavage sites and provides a high degree of sequence coverage (90-100%). Post-translational modification issues can be addressed too. This approach might help those mass spectrometry (MS) core facilities that are not able to afford very high-resolution instruments, thus expanding the benefits of top-down protein analysis over the worldwide MS community.

  1. Design of a backscatter 14-MeV neutron time-of-flight spectrometer for experiments at ITER

    SciTech Connect

    Dzysiuk, N.; Hellesen, C.; Conroy, S.; Ericsson, G.; Hjalmarsson, A.; Skiba, M.

    2014-08-21

    Neutron energy spectrometry diagnostics play an important role in present-day experiments related to fusion energy research. Measurements and thorough analysis of the neutron emission from the fusion plasma give information on a number of basic fusion performance quantities, on the condition of the neutron source and plasma behavior. Here we discuss the backscatter Time-of-Flight (bTOF) spectrometer concept as a possible instrument for performing high resolution measurements of 14 MeV neutrons. The instrument is based on two sets of scintillators, a first scatterer exposed to a collimated neutron beam and a second detector set placed in the backward direction. The scintillators of the first set are enriched in deuterium to achieve neutron backscattering. The energy resolution and efficiency of a bTOF instrument have been determined for various geometrical configurations. A preliminary design of optimal geometry for the two scintillator sets has been obtained by Monte Carlo simulations based on the MCNPX code.

  2. Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry

    PubMed Central

    Park, Jonghoo; Blick, Robert H.

    2016-01-01

    We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. PMID:26861329

  3. High Resolution Formaldehyde Photochemistry

    NASA Astrophysics Data System (ADS)

    Ernest, C. T.; Bauer, D.; Hynes, A. J.

    2010-12-01

    Formaldehyde (HCHO) is the most abundant and most important organic carbonyl compound in the atmosphere. The sources of formaldehyde are the oxidation of methane, isoprene, acetone, and other volatile organic compounds (VOCs); fossil fuel combustion; and biomass burning. The dominant loss mechanism for formaldehyde is photolysis which occurs via two pathways: (R1) HCHO + hv → HCO + H (R2) HCHO + hv → H2 + CO The first pathway (R1) is referred to as the radical channel, while the second pathway (R2) is referred to as the molecular channel. The products of both pathways play a significant role in atmospheric chemistry. The CO that is produced in the molecular channel undergoes further oxidation to produce CO2. Under atmospheric conditions, the H atom and formyl radical that are produced in the radical channel undergo rapid reactions with O2 to produce the hydroperoxyl radical (HO2) via (R3) and (R4). (R3) HCO + O2 → HO2 + CO (R4) H + O2 → HO2 Thus, for every photon absorbed, the photolysis of formaldehyde can contribute one CO2 molecule to the global greenhouse budget or two HO2 radicals to the tropospheric HOx (OH + HO2) cycle. The HO2 radicals produced during formaldehyde photolysis have also been implicated in the formation of photochemical smog. The HO2 radicals act as radical chain carriers and convert NO to NO2, which ultimately results in the catalytic production of O3. Constraining the yield of HO2 produced via HCHO photolysis is essential for improving tropospheric chemistry models. In this study, both the absorption cross section and the quantum yield of the radical channel (R1) were measured at high resolution over the tropospherically relevant wavelength range 304-330 nm. For the cross section measurements a narrow linewidth Nd:YAG pumped dye laser was used with a multi-pass cell. Partial pressures of HCHO were kept below 0.3 torr. Simultaneous measurement of OH LIF in a flame allowed absolute calibration of the wavelength scale. Pressure

  4. Time-of-Flight Adjustment Procedure for Acoustic Measurements in Structural Timber

    Treesearch

    Danbiel F. Llana; Guillermo Iñiguez-Gonzalez; Francisco Arriaga; Xiping Wang

    2016-01-01

    The effect of timber length on time-of-flight acoustic longitudinal measurements was investigated on the structural timber of four Spanish species: radiata pine (Pinus radiata D. Don), Scots pine (Pinus sylvestris L.), laricio pine (Pinus nigra Arn.), and maritime pine (Pinus pinaster Ait.). Time-of-flight longitudinal measurements were conducted on 120 specimens of...

  5. High resolution time interval meter

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

  6. High energy collisions on tandem time-of-flight mass spectrometers.

    PubMed

    Cotter, Robert J

    2013-05-01

    Long before the introduction of matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI), Orbitraps, and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were, nonetheless, some clear advantages for sectors over their low collision energy counterparts. Time-of-flight (TOF) mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective, we recount our own journey to produce high performance TOFs and tandem TOFs, describing the basic theory, problems, and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages, and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging, and the characterization of microorganisms.

  7. Applications of time-of-flight lidar in crater geology

    NASA Astrophysics Data System (ADS)

    Berinstain, Alain; Osinski, Gordon; Spray, John; Lee, Pascal; Hahn, John; Ulitsky, Arkady

    2003-08-01

    Devon Island, in the Canadian High Arctic (75°22"N, 89°41"W), is the largest uninhabited island on the planet. The climate is that of a polar desert; it is cold, dry, dusty, rocky, and almost void of any vegetation. The eastern part of the island is still covered by an ice cap, a remnant of the Inuitian Ice Sheet system that covered the bulk of the area during the last Glacial Maximum 8 000-10 000 years ago.. The island is rich in well-preserved geology, relatively free of erosion. The feature of highest scientific interest on Devon Island is the ~23-million-year-old (Miocene), ~24 km diameter Haughton impact structure.. There are few other craters on this planet as well preserved and exposed as Haughton, mainly due to the unique climate that slows down erosion common on the rest of the planet.The NASA Haughton-Mars project is an international planetary analog research project headquartered at NASA Ames Research Centre and managed by the SETI Institute. The lidar work described in this work is a collaborative activity between the SETI Institute, the University of Guelph, the University of New Brunswick, Optech Inc., and the Canadian Space Agency. Field activities were conducted under the auspices of the NASA HMP and of the CSA. Specific sites of geological interest within Haughton impact structure were imaged using an Optech Ilris 3-d ground-surveying unit. This very high-resolution, 3-dimensional data allows for the field geologist to "re-visit" a field site well after the field season has finished. In this work, we will present the results of 3-dimensional scans of an ejecta block and of impact-generated rock formations that contribute to furthering our understanding of impact cratering, a fundamental and universal process of planetary formation and evolution, and to studies of the erosional history of Haughton Crater and surrounding terrain on Devon Island. We will demonstrate how using this tool in the field can increase safety and allow for precise

  8. Neutron-induced fission cross section of U234 and Np237 measured at the CERN Neutron Time-of-Flight (n_TOF) facility

    NASA Astrophysics Data System (ADS)

    Paradela, C.; Tassan-Got, L.; Audouin, L.; Berthier, B.; Duran, I.; Ferrant, L.; Isaev, S.; Le Naour, C.; Stephan, C.; Tarrío, D.; Trubert, D.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Álvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Badurek, G.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapiço, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; González-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krtička, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martínez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Tagliente, G.; Tain, J. L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2010-09-01

    A high-resolution measurement of the neutron-induced fission cross section of U234 and Np237 has been performed at the CERN Neutron Time-of-Flight facility. The cross sections have been determined in a wide energy range from 1 eV to 1 GeV using the evaluated U235 cross section as reference. In these measurements the energy determination for the U234 resonances could be improved, whereas previous discrepancies for the Np237 resonances were confirmed. New cross-section data are provided for high neutron energies that go beyond the limits of prior evaluations, obtaining important differences in the case of Np237.

  9. An accurate air temperature measurement system based on an envelope pulsed ultrasonic time-of-flight technique

    NASA Astrophysics Data System (ADS)

    Huang, Y. S.; Huang, Y. P.; Huang, K. N.; Young, M. S.

    2007-11-01

    A new microcomputer based air temperature measurement system is presented. An accurate temperature measurement is derived from the measurement of sound velocity by using an ultrasonic time-of-flight (TOF) technique. The study proposes a novel algorithm that combines both amplitude modulation (AM) and phase modulation (PM) to get the TOF measurement. The proposed system uses the AM and PM envelope square waveform (APESW) to reduce the error caused by inertia delay. The APESW ultrasonic driving waveform causes an envelope zero and phase inversion phenomenon in the relative waveform of the receiver. To accurately achieve a TOF measurement, the phase inversion phenomenon was used to sufficiently identify the measurement pulse in the received waveform. Additionally, a counter clock technique was combined to compute the phase shifts of the last incomplete cycle for TOF. The presented system can obtain 0.1% TOF resolution for the period corresponding to the 40kHz frequency ultrasonic wave. Consequently, with the integration of a humidity compensation algorithm, a highly accurate and high resolution temperature measurement can be achieved using the accurate TOF measurement. Experimental results indicate that the combined standard uncertainty of the temperature measurement is approximately 0.39°C. The main advantages of this system are high resolution measurements, narrow bandwidth requirements, and ease of implementation.

  10. Workflow development for targeted lipidomic quantification using parallel reaction monitoring on a quadrupole-time of flight mass spectrometry.

    PubMed

    Zhou, Juntuo; Liu, Chunlei; Si, Dandan; Jia, Bing; Zhong, Lijun; Yin, Yuxin

    2017-06-15

    Advances in high-resolution mass spectrometers with faster scanning capabilities and higher sensitivities have expanded these instruments' functionality beyond traditional data-dependent acquisition in targeted metabolomics. Apart from the traditional multiple reaction monitoring strategy, the parallel reaction monitoring (PRM) strategy is also used for targeted metabolomics quantification. The high resolution and mass accuracy of full-scan (MS1) and tandem mass spectrometry (MS/MS) scan result in sufficient selectivity by monitoring all MS/MS fragment ions for each target precursor and simultaneously providing flexibility in assay method construction and post-acquisition data analysis. In this study, using an orthogonal quadrupole-time of flight liquid chromatography-mass spectrometry system (QTOF LC-MS), we investigated the applicability of a large-scale targeted lipidomic assay using scheduled PRM. This method monitored 222 lipids belonging to 15 lipid species in serum. Robustness, reproducibility, and quantitative performance were assessed using chemical standards and serum samples. Finally, we demonstrated the application of this PRM-based targeted metabolomic workflow to systemic lupus erythematosus, a severe autoimmunological disease. Results showed that 63 lipids belonging to 11 lipid species were significantly changed. In summary, at the first time, a robust targeted lipidomic workflow was established using PRM acquisition strategy on a Q-TOF platform, providing another powerful tool for targeted metabolomic analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Applying of the optical time-of-flight spectroscopy for the paper and pulp characterization

    NASA Astrophysics Data System (ADS)

    Pluciński, Jerzy

    2006-02-01

    The paper presents benefits of optical time-of-flight spectroscopy for the pulp and paper characterization. A semiconductor pulse laser and a streak camera as the photodetector were utilized in experimental part of research described in this paper. Distribution of the time of flight of photons through various kinds of wood pulp (e.g. pulp after mechanical treatment coming both fi-om tree species giving hard and soft wood and pulp after thermo-mechanical treatment) was measured. The pulp samples used in the measurements had consistency ranging from 0 to 5% of dry mass in the suspension. The influence of additives (kaolin, talc and calcium carbonate) present in the suspension on the time of flight distribution of photons was studied as well. Finally, dependence of the time of flight of photons through various kinds of the paper (i.e. newspaper, copy paper, and tissue) on the thickness of the sample was investigated.

  12. Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

    NASA Astrophysics Data System (ADS)

    Engle, Brady J.; Schmerr, Lester W., Jr.; Sedov, Alexander

    2013-01-01

    Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size.

  13. Dielectric resistive plate chamber—the first step in new high-resolution TOF technology

    NASA Astrophysics Data System (ADS)

    Akindinov, A.; Golovine, V.; Martemianov, A.; Petrov, V.; Smirnitski, A.; Voloshin, K.

    2002-11-01

    Modern high-energy nuclear physics experiments, in which many thousands of particles are produced, require qualitatively new detectors for particle identification (PID). Dielectric Resistive Plate Chamber (DRPC) is one of the first options of a new high-resolution time-measuring technology. It was invented and studied during the initial stage of R&D for the ALICE/LHC PID system based on Time-of-Flight measurements. In this article, the main DRPC features are described.

  14. High resolution TOF - SIMS depth profiling of nano-film multilayers

    SciTech Connect

    Bhushan, K. G.; Mukundhan, R.; Gupta, S. K.

    2013-02-05

    We present the results of depth profiling studies conducted using an indigenously developed dual-beam high resolution Time-of-Flight Secondary Ion Mass Spectrometer (TOF-SIMS) on thinfilm W-C-W multilayer structure grown on Si substrate. Opto 8 layers could be clearly identified. Mixing of layers is seen which from analysis using roughness model calculations indicate a mixing thickness of about 2nm that correspond to the escape depth of secondary ions from the sample.

  15. A multi-DSP system for the neutron high resolution Fourier diffractometer

    SciTech Connect

    Drozdov, V.A.; Butenko, V.A.; Prikhodko, V.I.

    1998-08-01

    The multi-DSP data acquisition system for neutron time-of-flight spectrum measurements requiring fast real-time data processing is designed and is operated at the neutron High Resolution Fourier Diffractometer (HRFD). The use of high performance DSPs and front-end electronics based on flexible PLDs allows increasing of the efficiency of neutron diffractometers with a Fourier chopper and a multi-element detector system by the method of electronic time-focusing.

  16. Automatic layout of integrated-optic time-of-flight circuits

    NASA Astrophysics Data System (ADS)

    Fogg, Ruth D.

    1996-11-01

    This work describes the architecture and algorithms used in the computer-aided design tool developed for the automatic layout of integrated-optic, time-of-flight circuit designs. As in VLSI circuit layout, total wire length and chip area minimization are the goals in the layout of time-of-flight circuits. However, there are two major differences between the layout of time of flight circuits and VLSI circuits. First, the interconnection lengths of time-of-flight designs are exactly specified in order to achieve the necessary delays for signal synchronization. SEcondly, the switching elements are 120 times longer than they are wide. This highly astigmatic aspect ratio causes severe constraints on how and where the switches are placed. Assuming the continued development of corner turning mirrors allows the use of a parallel, row-based device placement architecture and a rectangular, fixed-grid track system for the connecting paths. The layout process proceeds in two steps. The first step involves the use of a partial circuit graph representation to place the elements in rows, oriented in the direction of the signal flow. After iterative improvement of the placement, the second step proceeds with the routing of the connecting paths. The main problem in the automatic layout of time-of-flight circuits is achieving the correct path lengths without overlapping previously routed paths. This problem is solved by taking advantage of a certain degree of variability present in each path, allowing the use of simple heuristics to circumvent previously routed paths.

  17. Assessing and minimizing contamination in time of flight based validation data

    NASA Astrophysics Data System (ADS)

    Lennox, Kristin P.; Rosenfield, Paul; Blair, Brenton; Kaplan, Alan; Ruz, Jaime; Glenn, Andrew; Wurtz, Ronald

    2017-10-01

    Time of flight experiments are the gold standard method for generating labeled training and testing data for the neutron/gamma pulse shape discrimination problem. As the popularity of supervised classification methods increases in this field, there will also be increasing reliance on time of flight data for algorithm development and evaluation. However, time of flight experiments are subject to various sources of contamination that lead to neutron and gamma pulses being mislabeled. Such labeling errors have a detrimental effect on classification algorithm training and testing, and should therefore be minimized. This paper presents a method for identifying minimally contaminated data sets from time of flight experiments and estimating the residual contamination rate. This method leverages statistical models describing neutron and gamma travel time distributions and is easily implemented using existing statistical software. The method produces a set of optimal intervals that balance the trade-off between interval size and nuisance particle contamination, and its use is demonstrated on a time of flight data set for Cf-252. The particular properties of the optimal intervals for the demonstration data are explored in detail.

  18. Bayesian Peptide Peak Detection for High Resolution TOF Mass Spectrometry

    PubMed Central

    Zhang, Jianqiu; Zhou, Xiaobo; Wang, Honghui; Suffredini, Anthony; Zhang, Lin; Huang, Yufei; Wong, Stephen

    2011-01-01

    In this paper, we address the issue of peptide ion peak detection for high resolution time-of-flight (TOF) mass spectrometry (MS) data. A novel Bayesian peptide ion peak detection method is proposed for TOF data with resolution of 10 000–15 000 full width at half-maximum (FWHW). MS spectra exhibit distinct characteristics at this resolution, which are captured in a novel parametric model. Based on the proposed parametric model, a Bayesian peak detection algorithm based on Markov chain Monte Carlo (MCMC) sampling is developed. The proposed algorithm is tested on both simulated and real datasets. The results show a significant improvement in detection performance over a commonly employed method. The results also agree with expert’s visual inspection. Moreover, better detection consistency is achieved across MS datasets from patients with identical pathological condition. PMID:21544266

  19. High resolution digital delay timer

    DOEpatents

    Martin, Albert D.

    1988-01-01

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

  20. High-resolution electron microscope

    NASA Technical Reports Server (NTRS)

    Nathan, R.

    1977-01-01

    Employing scanning transmission electron microscope as interferometer, relative phases of diffraction maximums can be determined by analysis of dark field images. Synthetic aperture technique and Fourier-transform computer processing of amplitude and phase information provide high resolution images at approximately one angstrom.

  1. Advanced very high resolution radiometer

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The advanced very high resolution radiometer development program is considered. The program covered the design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical structural model, and a life test model. Special bench test and calibration equipment was also developed for use on the program.

  2. High Resolution Orientation Imaging Microscopy

    DTIC Science & Technology

    2012-05-02

    Functions, ICCES 2010, Las Vegas. 17. David Fullwood, Brent Adams, Mike Miles, Stuart Rogers, Ali Khosravani, Raj Mishra, Design for Ductility : Defect... Pseudo -Symmetries by High Resolution EBSD Methods, MS&T. 2009: Pittsburgh. 27. Oliver Johnson, Calvin Gardner, David Fullwood, Brent Adams, George...applied to strain measurements ................................... 6 2.3 Recovery of Lattice Tetragonality and Pseudo -Symmetry Resolution

  3. Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

    SciTech Connect

    Jacobsen, A. S. Salewski, M.; Korsholm, S. B.; Leipold, F.; Nielsen, S. K.; Rasmussen, J.; Stejner, M.; Eriksson, J.; Ericsson, G.; Hjalmarsson, A.

    2014-11-15

    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR.

  4. Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET.

    PubMed

    Jacobsen, A S; Salewski, M; Eriksson, J; Ericsson, G; Hjalmarsson, A; Korsholm, S B; Leipold, F; Nielsen, S K; Rasmussen, J; Stejner, M

    2014-11-01

    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR.

  5. The ROTAX/DIFF time-of-flight diffractometer at ISIS

    NASA Astrophysics Data System (ADS)

    Tietze-Jaensch, H.; Kockelmann, W.; Schmidt, W.; Will, G.

    1997-02-01

    We report on the setup of the ROTAX instrument as a conventional angle-dispersive time-of-flight diffractometer. This utilisation of the instrument not only provides a powerful and very versatile tool for many bread-and-butter applications in crystallographic and magnetic structure determination but also exploits the methods of single-crystal diffraction of quasi-Laue and diffuse scattering. White beam neutron time-of-flight diffraction expands to a very economic way of obtaining pole figures for texture analysis in bulk-material and earth sciences. Generally speaking, an overall gain-factor of 5-10 is practically achieved compared to an equivalent constant wavelength instrument.

  6. Single-photon pulsed-light indirect time-of-flight 3D ranging.

    PubMed

    Bellisai, S; Bronzi, D; Villa, F A; Tisa, S; Tosi, A; Zappa, F

    2013-02-25

    "Indirect" time-of-flight is one technique to obtain depth-resolved images through active illumination that is becoming more popular in the recent years. Several methods and light timing patterns are used nowadays, aimed at improving measurement precision with smarter algorithms, while using less and less light power. Purpose of this work is to present an indirect time-of-flight imaging camera based on pulsed-light active illumination and a 32 × 32 single-photon avalanche diode array with an improved illumination timing pattern, able to increase depth resolution and to reach single-photon level sensitivity.

  7. Potential advantages of a cesium fluoride scintillator for a time-of-flight positron camera.

    PubMed

    Allemand, R; Gresset, C; Vacher, J

    1980-02-01

    In order to improve the quality of positron tomographic imaging, a time-of-flight technique combined with a classical reconstruction method has been investigated. The decay time of NaI(Tl) and bismuth germanate (BGO) scintillators is too long for this application, and efficiency of the plastic scintillators is too low. Cesium fluoride appears to be a very promising detector material. This paper presents preliminary results obtained with a time-of-flight technique using CsF scintillators. The expected advantages were realized.

  8. Precision electronics for a system of custom MCPs in the TORCH Time of Flight detector

    NASA Astrophysics Data System (ADS)

    Gao, R.; Brook, N.; Castillo García, L.; Conneely, T.; Cussans, D.; Föhl, K.; Forty, R.; Frei, C.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; Van Dijk, M.

    2017-03-01

    The TORCH detector will provide charged particle pi/K/p identification up to 10 GeV/c, combining Time-of-Flight and Cherenkov techniques to achieve a timing resolution of 70 ps for single photons. Based on a scalable design, a Time-of-Flight electronics readout system has been developed to instrument a novel customized 512-channel Micro Channel Plate (MCP) device. A Gigabit Ethernet-based readout scheme that operates the TORCH demonstration unit consisting of ten such MCPs will be reported. The trigger and clock distribution will also be discussed.

  9. Design, construction, characterization and use of a detector to measure time of flight of cosmic rays

    NASA Astrophysics Data System (ADS)

    Araujo, A. C.; Félix, J.

    2016-10-01

    In the study of cosmic rays, measurements of time of flight and momentum have been used to identify incident particles from its physical properties, like mass. In this poster we present the design, construction, characterization, and operation of a detector to measure time of flight of cosmic rays. The device is comprised of three plates of plastic scintillator arranged in vertical straight line, they are coupled to one photomultiplier tube. The analogical output has been connected to a data acquisition system to obtain the number of digital pulses per millisecond. We present preliminary results.

  10. Profiling and characterizing skin ceramides using reversed-phase liquid chromatography-quadrupole time-of-flight mass spectrometry.

    PubMed

    t'Kindt, Ruben; Jorge, Lucie; Dumont, Emmie; Couturon, Pauline; David, Frank; Sandra, Pat; Sandra, Koen

    2012-01-03

    An LC-MS based method for the profiling and characterization of ceramide species in the upper layer of human skin is described. Ceramide samples, collected by tape stripping of human skin, were analyzed by reversed-phase liquid chromatography coupled to high-resolution quadrupole time-of-flight mass spectrometry operated in both positive and negative electrospray ionization mode. All known classes of ceramides could be measured in a repeatable manner. Furthermore, the data set showed several undiscovered ceramides, including a class with four hydroxyl functionalities in its sphingoid base. High-resolution MS/MS fragmentation spectra revealed that each identified ceramide species is composed of several skeletal isomers due to variation in carbon length of the respective sphingoid bases and fatty acyl building blocks. The resulting variety in skeletal isomers has not been previously demonstrated. It is estimated that over 1000 unique ceramide structures could be elucidated in human stratum corneum. Ceramide species with an even and odd number of carbon atoms in both chains were detected in all ceramide classes. Acid hydrolysis of the ceramides, followed by LC-MS analysis of the end-products, confirmed the observed distribution of both sphingoid bases and fatty acyl groups in skin ceramides. The study resulted in an accurate mass retention time library for targeted profiling of skin ceramides. It is furthermore demonstrated that targeted data processing results in an improved repeatability versus untargeted data processing (72.92% versus 62.12% of species display an RSD < 15%). © 2011 American Chemical Society

  11. Coupled Space- and Velocity-Focusing in Time-of-Flight Mass Spectrometry-a Comprehensive Theoretical Investigation.

    PubMed

    Cai, Yi-Hong; Lai, Yin-Hung; Wang, Yi-Sheng

    2015-10-01

    A comprehensive theoretical calculation that couples space- and velocity-focusing is developed for optimizing the design of a time-of-flight (TOF) mass spectrometer. Conventional designs for ion sources of TOF mass spectrometers deviate from the optimal condition because the velocity- and space-focusing conditions are considered separately for two ions with simplified equations. The result of a reexamination taking into account all essential ions reveals that the conventional ion source design, especially the length of the ion extraction region, results in poor resolving power. The comprehensive calculation demonstrates that the resolving power increases when the length of the extraction region is shorter than that of the conventional ion source. A numerical analysis indicates that the resolving power dramatically increases when the effective extraction potential compensates for the initial kinetic energy spread of ions. With typically used extraction potentials, the newly optimized ion source improves the resolving power by more than two orders of magnitude compared with the conventional design. This new theoretical interpretation can also be used to predict the optimal extraction potential and extraction delay in conventional ion sources to substantially improve the resolving power. This comprehensive calculation method is effective not only for designing new high-resolution instruments but also for optimizing commercial products.

  12. Coupled Space- and Velocity-Focusing in Time-of-Flight Mass Spectrometry—a Comprehensive Theoretical Investigation

    NASA Astrophysics Data System (ADS)

    Cai, Yi-Hong; Lai, Yin-Hung; Wang, Yi-Sheng

    2015-07-01

    A comprehensive theoretical calculation that couples space- and velocity-focusing is developed for optimizing the design of a time-of-flight (TOF) mass spectrometer. Conventional designs for ion sources of TOF mass spectrometers deviate from the optimal condition because the velocity- and space-focusing conditions are considered separately for two ions with simplified equations. The result of a reexamination taking into account all essential ions reveals that the conventional ion source design, especially the length of the ion extraction region, results in poor resolving power. The comprehensive calculation demonstrates that the resolving power increases when the length of the extraction region is shorter than that of the conventional ion source. A numerical analysis indicates that the resolving power dramatically increases when the effective extraction potential compensates for the initial kinetic energy spread of ions. With typically used extraction potentials, the newly optimized ion source improves the resolving power by more than two orders of magnitude compared with the conventional design. This new theoretical interpretation can also be used to predict the optimal extraction potential and extraction delay in conventional ion sources to substantially improve the resolving power. This comprehensive calculation method is effective not only for designing new high-resolution instruments but also for optimizing commercial products.

  13. A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry

    SciTech Connect

    Jozwiak, Chris M.; Graff, Jeff; Lebedev, Gennadi; Andresen, Nord; Schmid, Andreas; Fedorov, Alexei; El Gabaly, Farid; Wan, Weishi; Lanzara, Alessandra; Hussain, Zahid

    2010-04-13

    We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90 degrees bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.

  14. Analysis of synthetic canine training aids by comprehensive two-dimensional gas chromatography-time of flight mass spectrometry.

    PubMed

    Stadler, Sonja; Stefanuto, Pierre-Hugues; Byer, Jonathan D; Brokl, Michał; Forbes, Shari; Focant, Jean-François

    2012-09-14

    Cadaver dogs are trained on a variety of materials, including artificial or pseudo scents. The chemical components of commercially available pseudo scents are not known, so their accuracy as a decomposition odour mimic and their effectiveness as a canine training aid have not been evaluated. Two pseudo scents that are commercially available and used for training cadaver dogs were analysed using comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-TOFMS). The two formulations were determined to be simplistic in their composition, compared to real cadaveric volatile organic compound (VOC) mixtures, with only a few major components. The enhanced GC×GC-TOFMS peak capacity was nevertheless useful to discriminate less intense peaks from large overloaded peaks. The availability of both dimension retention times combined with the peak finding and deconvolution algorithm, enabled the chemical characterization of the two formulations. Additionally, high resolution (HR) TOFMS was used to extract molecular formulae and confirm identities of analytes. The seven compounds identified by this work have not been reported previously as volatile products of decomposition, indicating that these pseudo scents are not to be considered as an accurate representation of cadaveric decomposition odour. Further research on the olfaction of scent detection canines and the chemical composition of their target odourants needs to be conducted to develop improved canine training aids. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Indoor and outdoor depth imaging of leaves with time-of-flight and stereo vision sensors: Analysis and comparison

    NASA Astrophysics Data System (ADS)

    Kazmi, Wajahat; Foix, Sergi; Alenyà, Guillem; Andersen, Hans Jørgen

    2014-02-01

    In this article we analyze the response of Time-of-Flight (ToF) cameras (active sensors) for close range imaging under three different illumination conditions and compare the results with stereo vision (passive) sensors. ToF cameras are sensitive to ambient light and have low resolution but deliver high frame rate accurate depth data under suitable conditions. We introduce metrics for performance evaluation over a small region of interest. Based on these metrics, we analyze and compare depth imaging of leaf under indoor (room) and outdoor (shadow and sunlight) conditions by varying exposure times of the sensors. Performance of three different ToF cameras (PMD CamBoard, PMD CamCube and SwissRanger SR4000) is compared against selected stereo-correspondence algorithms (local correlation and graph cuts). PMD CamCube has better cancelation of sunlight, followed by CamBoard, while SwissRanger SR4000 performs poorly under sunlight. Stereo vision is comparatively more robust to ambient illumination and provides high resolution depth data but is constrained by texture of the object along with computational efficiency. Graph cut based stereo correspondence algorithm can better retrieve the shape of the leaves but is computationally much more expensive as compared to local correlation. Finally, we propose a method to increase the dynamic range of ToF cameras for a scene involving both shadow and sunlight exposures at the same time by taking advantage of camera flags (PMD) or confidence matrix (SwissRanger).

  16. First spatial separation of a heavy ion isomeric beam with a multiple-reflection time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Dickel, T.; Plaß, W. R.; Ayet San Andres, S.; Ebert, J.; Geissel, H.; Haettner, E.; Hornung, C.; Miskun, I.; Pietri, S.; Purushothaman, S.; Reiter, M. P.; Rink, A.-K.; Scheidenberger, C.; Weick, H.; Dendooven, P.; Diwisch, M.; Greiner, F.; Heiße, F.; Knöbel, R.; Lippert, W.; Moore, I. D.; Pohjalainen, I.; Prochazka, A.; Ranjan, M.; Takechi, M.; Winfield, J. S.; Xu, X.

    2015-05-01

    211Po ions in the ground and isomeric states were produced via 238U projectile fragmentation at 1000 MeV/u. The 211Po ions were spatially separated in flight from the primary beam and other reaction products by the fragment separator FRS. The ions were energy-bunched, slowed-down and thermalized in a gas-filled cryogenic stopping cell (CSC). They were then extracted from the CSC and injected into a high-resolution multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). The excitation energy of the isomer and, for the first time, the isomeric-to-ground state ratio were determined from the measured mass spectrum. In the subsequent experimental step, the isomers were spatially separated from the ions in the ground state by an ion deflector and finally collected with a silicon detector for decay spectroscopy. This pioneering experimental result opens up unique perspectives for isomer-resolved studies. With this versatile experimental method new isomers with half-lives longer than a few milliseconds can be discovered and their decay properties can be measured with highest sensitivity and selectivity. These experiments can be extended to studies with isomeric beams in nuclear reactions.

  17. Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions

    SciTech Connect

    Donovan, D. C.; Boris, D. R.; Kulcinski, G. L.; Santarius, J. F.; Piefer, G. R.

    2013-03-15

    A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage ({approx}100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.

  18. Spin-filtered time-of-flight k-space microscopy of Ir - Towards the "complete" photoemission experiment.

    PubMed

    Schönhense, G; Medjanik, K; Chernov, S; Kutnyakhov, D; Fedchenko, O; Ellguth, M; Vasilyev, D; Zaporozhchenko-Zymaková, A; Panzer, D; Oelsner, A; Tusche, C; Schönhense, B; Braun, J; Minár, J; Ebert, H; Viefhaus, J; Wurth, W; Elmers, H J

    2017-07-06

    The combination of momentum microscopy (high resolution imaging of the Fourier plane) with an imaging spin filter has recently set a benchmark in k-resolution and spin-detection efficiency. Here we show that the degree of parallelization can be further increased by time-of-flight energy recording. On the quest towards maximum information (in earlier work termed "complete" photoemission experiment) we have studied the prototypical high-Z fcc metal iridium. Large partial bandgaps and strong spin-orbit interaction lead to a sequence of spin-polarized surface resonances. Soft X-rays give access to the 4D spectral density function ρ (EB,kx,ky,kz) weighted by the photoemission cross section. The Fermi surface and all other energy isosurfaces, Fermi velocity distribution vF(kF), electron or hole conductivity, effective mass and inner potential can be obtained from the multi-dimensional array ρ by simple algorithms. Polarized light reveals the linear and circular dichroism texture in a simple manner and an imaging spin filter exposes the spin texture. One-step photoemission calculations are in fair agreement with experiment. Comparison of the Bloch spectral function with photoemission calculations uncovers that the observed high spin polarization of photoelectrons from bulk bands originates from the photoemission step and is not present in the initial state. Copyright © 2017. Published by Elsevier B.V.

  19. Semiquantitative analysis of atherosclerotic plaque using optical coherence tomography and time-of-flight secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Korol, Renee M.; Togonu-Bickersteth, Babajide; Yang, Victor X.; Dimov, Stamen; Vatsya, Pracha; Gordon, Maggie; Vitkin, Alex; Liu, Liying; Canham, Peter; Clarke, Sharon; Lucas, Alexandra

    2003-10-01

    Atherosclerosis is the underlying vascular pathology that initiates arterial thromboembolic occlusions (myocardial infarctions, strokes and peripheral vessel blockage). Two imaging modalities, Optical Coherence Tomography (OCT) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), were investigated for detection and compositional analysis of unstable plaque associated with plaque erosion and sudden occlusion. OCT produces high resolution images whereas mass spectrometry images provide information on the spatial distribution of chemical elements. Diseased carotid arteries taken from patients with high-risk lesions were imaged with OCT and ToF-SIMS to give molecular and metabolic information, and matched with histopathology. OCT results show clear indications of vascular remodeling by the presence of fatty acid deposits, fibrous tissue and calcifications. ToF-SIMS further characterized changes based on secondary ion topography analysis where a high 23Na/39K ratio was indicative of arterial tissue degradation and the amount of 40Ca corresponded with late stage atherosclerosis. This pilot experiment has demonstrated that in vitro OCT imaging and ToF-SIMS of diseased carotid arteries have scientific merit for targeting clinically relevant morphology and metabolic changes to compare stable and unstable plaque. These optical techniques provide complimentary metabolic and molecular information on unstable plaque, specifically cell break-down with altered ion ratios of 23Na, 39K and 40Ca.

  20. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry

    PubMed Central

    Marin, Stephanie J.; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A.; Johnson-Davis, Kamisha L.

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs. PMID:26342055

  1. Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions

    NASA Astrophysics Data System (ADS)

    Donovan, D. C.; Boris, D. R.; Kulcinski, G. L.; Santarius, J. F.; Piefer, G. R.

    2013-03-01

    A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage (˜100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.

  2. Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions.

    PubMed

    Donovan, D C; Boris, D R; Kulcinski, G L; Santarius, J F; Piefer, G R

    2013-03-01

    A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage (∼100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.

  3. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    PubMed

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.

    PubMed

    Marin, Stephanie J; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A; Johnson-Davis, Kamisha L

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs.

  5. Quantitative analysis of naphthenic acids in water by liquid chromatography-accurate mass time-of-flight mass spectrometry.

    PubMed

    Hindle, Ralph; Noestheden, Matthew; Peru, Kerry; Headley, John

    2013-04-19

    This study details the development of a routine method for quantitative analysis of oil sands naphthenic acids, which are a complex class of compounds found naturally and as contaminants in oil sands process waters from Alberta's Athabasca region. Expanding beyond classical naphthenic acids (CnH2n-zO2), those compounds conforming to the formula CnH2n-zOx (where 2≥x≤4) were examined in commercial naphthenic acid and environmental water samples. HPLC facilitated a five-fold reduction in ion suppression when compared to the more commonly used flow injection analysis. A comparison of 39 model naphthenic acids revealed significant variability in response factors, demonstrating the necessity of using naphthenic acid mixtures for quantitation, rather than model compounds. It was also demonstrated that naphthenic acidic heterogeneity (commercial and environmental) necessitates establishing a single NA mix as the standard against which all quantitation is performed. The authors present the first ISO17025 accredited method for the analysis of naphthenic acids in water using HPLC high resolution accurate mass time-of-flight mass spectrometry. The method detection limit was 1mg/L total oxy-naphthenic acids (Sigma technical mix). Copyright © 2013 Elsevier B.V. All rights reserved.

  6. High-Resolution Radar Imaging

    DTIC Science & Technology

    1990-01-14

    vThe goal of this project is to formulate and investigate new approaches for forming images of radar targets from spotlight-mode, delay-doppler...the new methods we are studying. There are two modules in the program. The first module produces simulated radar back-scatter data. The simulation...gives the model and fundamental estimation equations for the method we are developing. The abstract is: "A new approach to high resolution radar

  7. Time-of-Flight Measurement of the Speed of Sound in a Metal Bar

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2016-01-01

    A simple setup was designed for a "time-of-flight" measurement of the sound speed in a metal bar. The experiment requires low cost components and is very simple to understand by students. A good use of it is as a demonstration experiment.

  8. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    ERIC Educational Resources Information Center

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  9. Time-of-Flight Measurement of the Speed of Sound in Water

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2016-01-01

    A simple setup is designed to investigate a "time-of-flight" measurement of the speed of sound in water. This experiment only requires low cost components and is also very simple to understand by students. It could be easily used as a demonstration experiment.

  10. Characterization of nanoparticles by matrix assisted laser desorption ionization time-of-flight mass spectrometry.

    PubMed

    Ramalinga, Uma; Clogston, Jeffrey D; Patri, Anil K; Simpson, John T

    2011-01-01

    Determining the molecular weight of nanoparticles can be challenging. The molecular weight characterization of dendrimers, for example, with varying covalent and noncovalent modifications is critical to their use as therapeutics. As such, we describe in this chapter a protocol for the analysis of these molecules by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).

  11. Multiple wavelength time-of-flight sensor based on time-correlated single-photon counting

    NASA Astrophysics Data System (ADS)

    Buller, Gerald S.; Harkins, Ross D.; McCarthy, Aongus; Hiskett, Philip A.; MacKinnon, Gordon R.; Smith, George R.; Sung, Raymond; Wallace, Andrew M.; Lamb, Robert A.; Ridley, Kevin D.; Rarity, John G.

    2005-08-01

    This article describes a time-of-flight sensor based on multiple pulsed laser sources which utilizes time-correlated single-photon counting. The sensor has demonstrated good performance at ranges of up to 17 km in daylight conditions. Analysis techniques were developed to examine the returns from targets containing more than one scattering surface.

  12. Time-of-Flight Measurement of the Speed of Sound in Water

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2016-01-01

    A simple setup is designed to investigate a "time-of-flight" measurement of the speed of sound in water. This experiment only requires low cost components and is also very simple to understand by students. It could be easily used as a demonstration experiment.

  13. Four-Spot Time-Of-Flight Laser Anemometer For Turbomachinery

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Skoch, Gary J.

    1995-01-01

    Two-color, four-spot time-of-flight laser anemometer designed for measuring flow velocity within narrow confines of small centrifugal compressor. Apparatus well suited for measuring fast (typical speeds 160 to 700 m/s), highly turbulent gas flows in turbomachinery. Other potential applications include measurement of gas flows in pipelines and in flows from explosions.

  14. Novel Solid-State Devices as Timing Detectors for Ion Time-of-Flight Measurements

    NASA Astrophysics Data System (ADS)

    Ogasawara, K.; Allegrini, F.; Desai, M. I.; Livi, S. A.

    2016-10-01

    This study reports on the performance of Avalanche Photodiode (APD) and Multi-Pixel Photon Counter (MPPC) as timing detectors for ion time-of-flight mass spectroscopy. APDs detect >10 keV ions directly, while MPPCs detect sub-keV secondary electrons.

  15. The time-of-flight system on the Goddard medium energy gamma-ray telescope

    NASA Technical Reports Server (NTRS)

    Ross, R. W.; Chesney, J. R.

    1979-01-01

    A scintillation counter time of flight system, incorporated into the Goddard 50 cm by 50 cm spark chamber gamma ray telescope is described. The system, which utilizes constant fractions timing and particle position compensation and digitizes up to 10 ns time differences to six bit accuracy in less than 500 ns is analyzed. The performance of this system during balloon flight is discussed.

  16. Laser desorption time-of-flight mass spectrometer DNA analyzer. Final report

    SciTech Connect

    Chen, C.H.W.; Martin, S.A.

    1997-02-01

    The objective of this project is the development of a laser desorption time-of-flight mass spectrometer DNA analyzer which can be broadly used for biomedical research. Tasks include: pulsed ion extraction to improve resolution; two-component matrices to enhance ionization; and solid phase DNA purification.

  17. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    ERIC Educational Resources Information Center

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  18. Sensitivity Upgrades to the Idaho Accelerator Center Neutron Time of Flight Spectrometer

    SciTech Connect

    Thompson, S. J.; Kinlaw, M. T.; Harmon, J. F.; Wells, D. P.; Hunt, A. W.

    2007-10-26

    Past experiments have shown that discrimination between between fissionable and non-fissionable materials is possible using an interrogation technique that monitors for high energy prompt fission neutrons. Several recent upgrades have been made to the neutron time of flight spectrometer at the Idaho Accelerator Center with the intent of increasing neutron detection sensitivity, allowing for system use in nonproliferation and security applications.

  19. Estimating time and time-lag in time-of-flight velocimetry

    NASA Technical Reports Server (NTRS)

    Lading, L.

    1983-01-01

    Estimating time and time-lag in time-of-flight velocimeters is investigated. Statistics of a filtered Poisson point process is given. A Maximum Likelihood Estimator is compared with suboptimum estimators in terms of robustness. For a dominating background combined spatial and temporal processing can improve the robustness compared with purely temporal processing. Schemes for the spatial filters are given.

  20. Estimating time and time-lag in time-of-flight velocimetry

    NASA Technical Reports Server (NTRS)

    Lading, L.

    1983-01-01

    Estimating time and time-lag in time-of-flight velocimeters is investigated. Statistics of a filtered Poisson point process is given. A Maximum Likelihood Estimator is compared with suboptimum estimators in terms of robustness. For a dominating background combined spatial and temporal processing can improve the robustness compared with purely temporal processing. Schemes for the spatial filters are given.

  1. Time-of-Flight Experiments in Molecular Motion and Electron-Atom Collision Kinematics

    ERIC Educational Resources Information Center

    Donnelly, Denis P.; And Others

    1971-01-01

    Describes a set of experiments for an undergraduate laboratory which demonstrates the relationship between velocity, mass, and temperature in a gas. The experimental method involves time-of-flight measurements on atoms excited to metastable states by electron impact. Effects resulting from recoil in the electron-atom collision can also be…

  2. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    SciTech Connect

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  3. Time-of-Flight Measurement of the Speed of Sound in a Metal Bar

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2016-01-01

    A simple setup was designed for a "time-of-flight" measurement of the sound speed in a metal bar. The experiment requires low cost components and is very simple to understand by students. A good use of it is as a demonstration experiment.

  4. Chemical characterization of particle emissions from controlled burns of biomass fuels using a high resolution time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Qi, L.; Hosseini, S.; Jung, H.; Yokelson, B.; Weise, D.; Cocker, D., III; Huang, Y.

    2012-03-01

    A total of forty-nine burns were conducted at the Missoula Fire Sciences Lab consisting of nine fuel types; i.e., chamise scrub oak, ceanothus, maritime chaparral, coastal sage scrub, California sage brush, Manzanita, oak savanna, oak woodland and masticated mesquite. This paper focuses on the chemical characterization of fine particle emissions collected for flaming, mixed and smoldering phases using a HR ToF-AMS. The evolution of OM/OC, H/C, O/C and N/C from fire ignition to extinction was measured to capture the transient and integrated chemical composition of the non-refractory portion of bulk particles. Real time elemental ratios and empirical formulas derived with respect to modified combustion efficiency (MCE) are reported. For each fuel, the hydrogen fragment ions dominate the unit mass resolution (UMR) mass spectra with no specific fragment ions attributable to an individual ecological combination. An interference ion in the UMR m/z 73, a fragment normally attributed to levoglucosan, is noted. Therefore, the results imply that C2H4O2+ (m/z 60.021) plus C3H5O2+ (m/z 73.029) are more sufficient to estimate the contribution of levoglucosan. The results did not show significant variations of levoglucosan content in the organic particle with the overall average contribution fraction ranging from 0.74% for coastal sage to 1.93% for chamise.

  5. CoMA: A high resolution Time-Of-Flight Secondary Ion Mass Spectrometer (TOF-SIMS) for in situ analysis of cometary matter

    NASA Technical Reports Server (NTRS)

    Zscheeg, Harry; Kissel, J.; Natour, G.

    1992-01-01

    A lot of clues concerning the origin of the solar system can be found by sending an exploring spacecraft to a rendezvous with a comet. The space experiment CoMA, which will measure the elemental, isotopic, and molecular composition of cometary dust grains is described. It will be flown on NASA's Comet Rendezvous Asteroid Flyby (CRAF) mission.

  6. Automatic layout of integrated-optics time-of-flight circuits

    NASA Astrophysics Data System (ADS)

    Kennett-Fogg, Ruth D.

    1995-04-01

    This work describes the architecture and algorithms used in the computer aided design tool developed for the automatic layout of integrated optic, time of flight circuit designs. This is similar to the layout of electronic VLSI circuits, where total wire length and chip area minimization are the major goals. Likewise, total wire length and chip area minimization are also the goals in the layout of time of flight circuits. However, there are two major differences between the layout of time of flight circuits and VLSI circuits. First, the interconnection lengths of time of flight designs are exactly specified in order to achieve the necessary delays for signal synchronization. Secondly, the switching elements are 120 times longer than they are wide. This highly astigmatic aspect ratio causes severe constraints on how and where the switches are placed. The assumed development of integrated corner turning mirrors allows the use of a parallel, row based device placement architecture and a rectangular, fixed grid track system for the connecting paths. The layout process proceeds in two steps. The first step involves the use of a partial circuit graph representation to place the elements in rows, oriented in the direction of the signal flow. After iterative improvement of the placement, the second step proceeds with the routing of the connecting paths. The main problem in the automatic layout of time of flight circuits is achieving the correct path lengths without overlapping previously routed paths. This problem is solved by taking advantage of a certain degree of variability present in each path, allowing the use of simple heuristics to circumvent previously routed paths.

  7. Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectra of poly(butylene adipate).

    PubMed

    Rizzarelli, Paola; Puglisi, Concetto; Montaudo, Giorgio

    2006-01-01

    Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS/MS) was employed to analyze four poly(butylene adipate) (PBAd) oligomers and to investigate their fragmentation pathways as a continuation of our work on the MALDI-TOF/TOF-MS/MS study of synthetic polymers. MALDI-TOF/TOF-MS/MS analysis was performed on oligomers terminated by carboxyl and hydroxyl groups, methyl adipate and hydroxyl groups, dihydroxyl groups, and dicarboxyl groups. The sodium adducts of these oligomers were selected as precursor ions. Different end groups do not influence the fragmentation of sodiated polyester oligomers and similar series of product ions were observed in all the MALDI-TOF/TOF-MS/MS spectra. According to the structures of the most abundant product ions identified in the present work, three fragmentation pathways have been proposed to occur most frequently in PBAd: beta-hydrogen-transfer rearrangement, leading to the selective cleavage of the --O--CH(2)-- bonds; --CH(2)--CH(2)-- (beta--beta) bond cleavage in the adipate moiety; and ester bond scission.

  8. High Resolution Scanning Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

    2000-01-01

    The present invention provides a High Resolution Scanning Reflectarray Antenna (HRSRA) for the purpose of tracking ground terminals and space craft communication applications. The present invention provides an alternative to using gimbaled parabolic dish antennas and direct radiating phased arrays. When compared to a gimbaled parabolic dish, the HRSRA offers the advantages of vibration free steering without incurring appreciable cost or prime power penalties. In addition, it offers full beam steering at a fraction of the cost of direct radiating arrays and is more efficient.

  9. High-resolution multiphoton cryomicroscopy.

    PubMed

    König, Karsten; Uchugonova, Aisada; Breunig, Hans Georg

    2014-03-15

    An ultracompact high-resolution multiphoton cryomicroscope with a femtosecond near infrared fiber laser has been utilized to study the cellular autofluorescence during freezing and thawing of cells. Cooling resulted in an increase of the intracellular fluorescence intensity followed by morphological modifications at temperatures below -10 °C, depending on the application of the cryoprotectant DMSO and the cooling rate. Furthermore, fluorescence lifetime imaging revealed an increase of the mean lifetime with a decrease in temperature. Non-destructive, label-free optical biopsies of biomaterial in ice can be obtained with sub-20 mW mean powers.

  10. A High Resolution CCD Multiplexer

    NASA Astrophysics Data System (ADS)

    Sheu, Larry S.; Kadekod i, Narayan; Nugroho, Yohanes; Lo, Mike; Mortz, Margaret; Ibrahim, Ali

    1983-11-01

    This paper describes a high resolution CCD multiplexer for focal plane imaging systems. The multiplexer incorporates quadrilinear readout registers to achieve two times the resolution of conventional bilinear structure while using the same design rules. Complete parallel charge transfer are ensured by a novel buried channel poly gate isolation scheme. A monolithic silicon photodiode array of 8 Am pitch, 3533 elements was designed with the multi-plexer. Video preprocessing circuits of high speed four to one channel stitching, compensated sample and hold and bad pixel deletion were integrated on chip for improved performance. The modulation transfer functions due to the geometry and the transfer inefficiency are discussed. The theoretically calculated total MTF agrees with the experimental result. At Nyquist frequency of 62.5 c/mm the total MTF is better than 0.6 in the absence of the diffusion MTF degradation. The noise spectrum of the CCD and the output amplifier are presented. The RMS noise of the CCD in dark is approximately 0.35 my over 1 MHz bandwidth. The CCD noise increases with light input attributed primarily to the shot noise. The low noise nature of the multiplexer makes it ideal for the high resolution low light level detection applications.

  11. Profiling the indole alkaloids in yohimbe bark with ultra-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry.

    PubMed

    Sun, Jianghao; Baker, Andrew; Chen, Pei

    2011-09-30

    An ultra-performance liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry (UPLC/IM-QTOF-MS) method was developed for profiling the indole alkaloids in yohimbe bark. Many indole alkaloids with the yohimbine or ajmalicine core structure, plus methylated, oxidized and reduced species, were characterized. Common fragments and mass differences are described. It was shown that the use of IMS could provide another molecular descriptor, i.e. molecular shape by rotationally averaged collision cross-section; this is of great value for identification of constituents when reference materials are usually not available. Using the combination of high resolution (~40000) accurate mass measurement with time-aligned parallel (TAP) fragmentation, MS(E) (where E represents collision energy), ion mobility mass spectrometry (IMS) and UPLC chromatography, a total 55 indole alkaloids were characterized and a few new indole alkaloids are reported for the first time.

  12. Validity of computational hemodynamics in human arteries based on 3D time-of-flight MR angiography and 2D electrocardiogram gated phase contrast images

    NASA Astrophysics Data System (ADS)

    Yu, Huidan (Whitney); Chen, Xi; Chen, Rou; Wang, Zhiqiang; Lin, Chen; Kralik, Stephen; Zhao, Ye

    2015-11-01

    In this work, we demonstrate the validity of 4-D patient-specific computational hemodynamics (PSCH) based on 3-D time-of-flight (TOF) MR angiography (MRA) and 2-D electrocardiogram (ECG) gated phase contrast (PC) images. The mesoscale lattice Boltzmann method (LBM) is employed to segment morphological arterial geometry from TOF MRA, to extract velocity profiles from ECG PC images, and to simulate fluid dynamics on a unified GPU accelerated computational platform. Two healthy volunteers are recruited to participate in the study. For each volunteer, a 3-D high resolution TOF MRA image and 10 2-D ECG gated PC images are acquired to provide the morphological geometry and the time-varying flow velocity profiles for necessary inputs of the PSCH. Validation results will be presented through comparisons of LBM vs. 4D Flow Software for flow rates and LBM simulation vs. MRA measurement for blood flow velocity maps. Indiana University Health (IUH) Values Fund.

  13. Comparison between triple quadrupole, time of flight and hybrid quadrupole time of flight analysers coupled to liquid chromatography for the detection of anabolic steroids in doping control analysis.

    PubMed

    Pozo, Oscar J; Van Eenoo, Peter; Deventer, Koen; Elbardissy, Hisham; Grimalt, Susana; Sancho, Juan V; Hernandez, Felix; Ventura, Rosa; Delbeke, Frans T

    2011-01-17

    Triple quadrupole (QqQ), time of flight (TOF) and quadrupole-time of flight (QTOF) analysers have been compared for the detection of anabolic steroids in human urine. Ten anabolic steroids were selected as model compounds based on their ionization and the presence of endogenous interferences. Both qualitative and quantitative analyses were evaluated. QqQ allowed for the detection of all analytes at the minimum required performance limit (MRPL) established by the World Anti-Doping Agency (between 2 and 10 ng mL(-1) in urine). TOF and QTOF approaches were not sensitive enough to detect some of the analytes (3'-hydroxy-stanozolol or the metabolites of boldenone and formebolone) at the established MRPL. Although a suitable accuracy was obtained, the precision was unsatisfactory (RSD typically higher than 20%) for quantitative purposes irrespective of the analyser used. The methods were applied to 30 real samples declared positives either for the misuse of boldenone, stanozolol and/or methandienone. Most of the compounds were detected by every technique, however QqQ was necessary for the detection of some metabolites in a few samples. Finally, the possibility to detect non-target steroids has been explored by the use of TOF and QTOF. The use of this approach revealed that the presence of boldenone and its metabolite in one sample was due to the intake of androsta-1,4,6-triene-3,17-dione. Additionally, the intake of methandienone was confirmed by the post-target detection of a long-term metabolite.

  14. A compact time-of-flight mass spectrometer for ion source characterization

    SciTech Connect

    Chen, L. Wan, X.; Jin, D. Z.; Tan, X. H.; Huang, Z. X.; Tan, G. B.

    2015-03-15

    A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters.

  15. TOF-VIS, software for interactive exploration of time-of-flight data

    NASA Astrophysics Data System (ADS)

    Mikkelson, D.; Worlton, T.

    TOF-VIS is a fast, highly interactive program for examining time-of-flight neutron-scattering data. All spectra from an experiment are displayed simultaneously as an image. The data can be displayed in terms of time-of-flight, energy, wave vector, or lattice spacing. TOF-VIS has been used for examining data from IPNS and ISIS, and has been useful for diagnosing problems with instruments and detectors as well as for making a quick evaluation of the quality of the data. Hard copy output to a variety of devices using routines built on PGPLOT is now available. TOF-VIS is portable to VMS and UNIX, and is currently implemented primarily using object-based methods in C, MOTIF and X-windows.

  16. Nitrogen depth profiling using recoil-nucleus time-of-flight spectrometry

    SciTech Connect

    Welsh, J.F. Jr.; Schweikert, E.A.

    1994-12-31

    Neutron depth profiling (NDP) has been shown to be an effective research tool for the profiling of light elements. Significant increases in sensitivity like those realized at the cold neutron NDP facility at the National Institute of Standards and Technology (NIST) reactor continue to advance the technique. Previous work has also shown that the depth resolution of NDP could be improved by measuring (via time of flight) the kinetic energies of recoil nuclei emitted during (n,p) and (n, {alpha}) reactions. The purpose of this work was to extend the technique of recoil-nucleus time-of-flight (TOF) NDP (RN-TOF-NDP) to the profiling of nitrogen in silicon nitride using the {sup 14}N(n,p) {sup 14}C reaction.

  17. Time-of-flight measurement with femtosecond pulses for high precision ranging lidar

    NASA Astrophysics Data System (ADS)

    Lee, J.; Kim, Y.-J.; Lee, K.; Lee, S.; Kim, S.-W.

    2010-10-01

    The time-of-flight of light pulses has long been used as a direct measure of distance, but the state-of-the-art measurement precision using conventional light pulses or microwaves reaches only several hundreds of micromeres. This is due to the bandwidth limit of the photodetectors available today, which is in the picosecond range at best. Here, we improve the time-of-flight precision to the nanometer regime by timing femtosecond pulses through phase-locking control of the pulse repetition rate using the optical cross-correlation technique that exploits a second-harmonic birefringence crystal and a balance photodetector. The enhanced capability is maintained at long range without periodic ambiguity, being well suited to terrestrial lidar applications such as geodetic surveying, range finders and absolute altimeters. This method could also be applied to future space missions of formation-flying satellites for synthetic aperture imaging and remote experiments related to the general relativity theory.

  18. Time of flight measurements of unirradiated and irradiated nuclear graphite under cyclic compressive load

    NASA Astrophysics Data System (ADS)

    Bodel, W.; Atkin, C.; Marsden, B. J.

    2017-04-01

    The time-of-flight technique has been used to investigate the stiffness of nuclear graphite with respect to the grade and grain direction. A loading rig was developed to collect time-of-flight measurements during cycled compressive loading up to 80% of the material's compressive strength and subsequent unloading of specimens along the axis of the applied stress. The transmission velocity (related to Young's modulus), decreased with increasing applied stress; and depending on the graphite grade and orientation, the modulus then increased, decreased or remained constant upon unloading. These tests were repeated while observing the microstructure during the load/unload cycles. Initial decreases in transmission velocity with compressive load are attributed to microcrack formation within filler and binder phases. Three distinct types of behaviour occur on unloading, depending on the grade, irradiation, and loading direction. These different behaviours can be explained in terms of the material microstructure observed from the microscopy performed during loading.

  19. Time of flight in MUSE at PIM1 at Paul Scherrer Institute

    NASA Astrophysics Data System (ADS)

    Lin, Wan; Gilman, Ronald; MUSE Collaboration

    2016-09-01

    The MUSE experiment at PIM1 at Paul Scherrer Institute in Villigen, Switzerland, measures elastic scattering of electrons and muons from a liquid hydrogen target. The intent of the experiment is to deduce whether the radius of the proton is the same when determined from the two different particle types. Precision timing is an important aspect of the experiment, used to determine particle types, reaction types, and beam momentum. Here we present results for a test setup measuring time of flight between prototypes of two detector systems to be used in the experiment, compared to Geant4 simulations. The results demonstrate time of flight resolution better than 100 ps, and beam momentum determination at the level of a few tenths of a percent. Douglass Project for Rutgers Women in Math, Science & Engineering, National Science Foundation Grant 1306126 to Rutgers University.

  20. Digitizing data acquisition and time-of-flight pulse processing for ToF-ERDA

    NASA Astrophysics Data System (ADS)

    Julin, Jaakko; Sajavaara, Timo

    2016-01-01

    A versatile system to capture and analyze signals from multi channel plate (MCP) based time-of-flight detectors and ionization based energy detectors such as silicon diodes and gas ionization chambers (GIC) is introduced. The system is based on commercial digitizers and custom software. It forms a part of a ToF-ERDA spectrometer, which has to be able to detect recoil atoms of many different species and energies. Compared to the currently used analogue electronics the digitizing system provides comparable time-of-flight resolution and improved hydrogen detection efficiency, while allowing the operation of the spectrometer be studied and optimized after the measurement. The hardware, data acquisition software and digital pulse processing algorithms to suit this application are described in detail.

  1. Invited article: Characterization of background sources in space-based time-of-flight mass spectrometers.

    PubMed

    Gilbert, J A; Gershman, D J; Gloeckler, G; Lundgren, R A; Zurbuchen, T H; Orlando, T M; McLain, J; von Steiger, R

    2014-09-01

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  2. Invited Article: Characterization of background sources in space-based time-of-flight mass spectrometers

    SciTech Connect

    Gilbert, J. A.; Gershman, D. J.; Gloeckler, G.; Lundgren, R. A.; Zurbuchen, T. H.; Orlando, T. M.; McLain, J.; Steiger, R. von

    2014-09-15

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  3. Beam derived trigger system for multibunch time-of-flight measurement

    SciTech Connect

    Fox, J.; Pellegrin, J.L.

    1981-01-01

    Particle time-of-flight measurement requires accurate triggers in synchronism with each bunch, and occurring in a sequence which depends on the position of the observer around the storage ring. A system has been devised for tagging the colliding bunches at each interaction point; it allows one to record which pair of bunches is colliding at any time and any location around the machine. Besides bunch identification, the time-of-flight triggers are also expected to have a time stability better than the bunch length itself. A system is presented here which exhibits time variations of less than 80 psec over a 20 to 1 range of beam current, while the jitter is at least an order of magnitude smaller. 4 refs., 4 figs.

  4. A Metrological Based Realization of Time-of-Flight Diffraction Technique

    NASA Astrophysics Data System (ADS)

    Mayworm, Ruan C.; Alvarenga, Andre V.; Costa-Felix, Rodrigo P. B.

    Time-of-Flight Diffraction (ToFD) is a technique of non-destructive testing by ultrasound used for detecting faults and discontinuities in different components. The development and implementation of this technique was based on ISO 16828:2012 (Non-Destructive testing - Ultrasonic Testing - Time-of-Flight Diffraction Technique as a method for Detection and Sizing of Discontinuities). Controlling the different characteristics of the system, from the specification of the ultrasonic characteristics, to the imaging technique, was possible to identify the sources of uncertainty and estimate the ToFD measurement uncertainty. For a 25 mm deep stainless steel test object, expanded uncertainties less than 0.5%(0.093 mm) was achieved with ToFD. For larger ultrasonic paths, the technique is able to depict even lower uncertainties, regarding some care are taken in the ultrasonic measurement setup.

  5. Study of ultrasonic thermometry based on ultrasonic time-of-flight measurement

    NASA Astrophysics Data System (ADS)

    Jia, Ruixi; Xiong, Qingyu; Wang, Lijie; Wang, Kai; Shen, Xuehua; Liang, Shan; Shi, Xin

    2016-03-01

    Ultrasonic thermometry is a kind of acoustic pyrometry and it has been evolving as a new temperature measurement technology for various environment. However, the accurate measurement of the ultrasonic time-of-flight is the key for ultrasonic thermometry. In this paper, we study the ultrasonic thermometry technique based on ultrasonic time-of-flight measurement with a pair of ultrasonic transducers for transmitting and receiving signal. The ultrasonic transducers are installed in a single path which ultrasonic travels. In order to validate the performance of ultrasonic thermometry, we make a contrast about the absolute error between the measured temperature value and the practical one. With and without heater source, the experimental results indicate ultrasonic thermometry has high precision of temperature measurement.

  6. Reliability Fusion of Time-of-Flight Depth and Stereo Geometry for High Quality Depth Maps.

    PubMed

    Zhu, Jiejie; Wang, Liang; Yang, Ruigang; Davis, James E; Pan, Zhigeng

    2011-07-01

    Time-of-flight range sensors have error characteristics, which are complementary to passive stereo. They provide real-time depth estimates in conditions where passive stereo does not work well, such as on white walls. In contrast, these sensors are noisy and often perform poorly on the textured scenes where stereo excels. We explore their complementary characteristics and introduce a method for combining the results from both methods that achieve better accuracy than either alone. In our fusion framework, the depth probability distribution functions from each of these sensor modalities are formulated and optimized. Robust and adaptive fusion is built on a pixel-wise reliability weighting function calculated for each method. In addition, since time-of-flight devices have primarily been used as individual sensors, they are typically poorly calibrated. We introduce a method that substantially improves upon the manufacturer's calibration. We demonstrate that our proposed techniques lead to improved accuracy and robustness on an extensive set of experimental results.

  7. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  8. Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Cross, E. S.; Onasch, T. B.; Canagaratna, M.; Jayne, J. T.; Kimmel, J.; Yu, X.-Y.; Alexander, M. L.; Worsnop, D. R.; Davidovits, P.

    2008-12-01

    We present the first single particle results obtained using an Aerodyne time-of-flight aerosol mass spectrometer coupled with a light scattering module (LS-ToF-AMS). The instrument was deployed at the T1 ground site approximately 40 km northeast of the Mexico City Metropolitan Area (MCMA) as part of the MILAGRO field study in March of 2006. The instrument was operated as a standard AMS from 12-30 March, acquiring average chemical composition and size distributions for the ambient aerosol, and in single particle mode from 27-30 March. Over a 75-h sampling period, 12 853 single particle mass spectra were optically triggered, saved, and analyzed. The correlated optical and chemical detection allowed detailed examination of single particle collection and quantification within the LS-ToF-AMS. The single particle data enabled the mixing states of the ambient aerosol to be characterized within the context of the size-resolved ensemble chemical information. The particulate mixing states were examined as a function of sampling time and most of the particles were found to be internal mixtures containing many of the organic and inorganic species identified in the ensemble analysis. The single particle mass spectra were deconvolved, using techniques developed for ensemble AMS data analysis, into HOA, OOA, NH4NO3, (NH4)2SO4, and NH4Cl fractions. Average single particle mass and chemistry measurements are shown to be in agreement with ensemble MS and PTOF measurements. While a significant fraction of ambient particles were internal mixtures of varying degrees, single particle measurements of chemical composition allowed the identification of time periods during which the ambient ensemble was externally mixed. In some cases the chemical composition of the particles suggested a likely source. Throughout the full sampling period, the ambient ensemble was an external mixture of combustion-generated HOA particles from local sources (e.g. traffic), with number concentrations peaking

  9. Neutron-induced fission measurements at the time-of-flight facility nELBE

    DOE PAGES

    Kögler, T.; Beyer, R.; Junghans, A. R.; ...

    2015-05-18

    Neutron-induced fission of ²⁴²Pu is studied at the photoneutron source nELBE. The relative fast neutron fission cross section was determined using actinide fission chambers in a time-of-flight experiment. A good agreement of present nuclear data with evalua- tions has been achieved in the range of 100 keV to 10 MeV.

  10. Neutron xyz - polarization analysis at a time-of-flight instrument

    SciTech Connect

    Ehlers, Georg; Stewart, John Ross; Andersen, Ken

    2015-01-01

    When implementing a dedicated polarization analysis setup at a neutron time-of-flight instrument with a large area detector, one faces enormous challenges. Nevertheless, significant progress has been made towards this goal over the last few years. This paper addresses systematic limitations of the traditional method that is used to make these measurements, and a possible strategy to overcome these limitations. This will be important, for diffraction as well as inelastic experiments, where the scattering occurs mostly out-of-plane.

  11. Detecting correlation functions of ultracold atoms through fourier sampling of time-of-flight images.

    PubMed

    Duan, L-M

    2006-03-17

    We propose a detection method for ultracold atoms which allows reconstruction of the full one-particle and two-particle correlation functions from the measurements. The method is based on Fourier sampling of the time-of-flight images through two consecutive impulsive Raman pulses. For applications of this method, we discuss a few examples, including detection of phase separation between superfluid and Mott insulators, various types of spin or superfluid orders, entanglement, exotic or fluctuating orders.

  12. Semen quality detection using time of flight and acoustic wave sensors

    SciTech Connect

    Newton, M. I.; Evans, C. R.; Simons, J. J.; Hughes, D. C.

    2007-04-09

    The authors report a real-time technique for assessing the number of motile sperm in a semen sample. The time of flight technique uses a flow channel with detection at the end of the channel using quartz crystal microbalances. Data presented suggest that a simple rigid mass model may be used in interpreting the change in resonant frequency using an effective mass for the sperm.

  13. Implementation of a new type of time-of-flight laser anemometer.

    PubMed

    Wernet, M P; Edwards, R V

    1986-03-01

    A new time-of-flight (TOF) laser anemometer system utilizing a spatial lead-lag filter for bipolar pulse generation has been constructed and tested. This new TOF has been modified to enable measurements in turbulent flows near walls. Good results have been obtained as close as 100 microm from a surface, with a 140-mm focal length final lens. Lading's theory for the behavior of the measurement variance has been confirmed for this configuration.

  14. Contactless flow measurement in liquid metal using electromagnetic time-of-flight method

    NASA Astrophysics Data System (ADS)

    Dubovikova, Nataliia; Resagk, Christian; Karcher, Christian; Kolesnikov, Yuri

    2016-05-01

    Measuring flow rates of liquid metal flows is of utmost importance in industrial applications such as metal casting, in order to ensure process efficiency and product quality. A non-contact method for flow rate control is described here. The method is known as time-of-flight Lorentz force velocimetry (LFV) and determines flow rate through measurement of Lorentz force that act on magnet systems that are placed close to the flow. In this method, a vortex generator is used to generate an eddy in the flow, with two magnet systems separated by a known distance placed downstream of the vortex generator. Each of the magnet systems has a force sensor attached to them which detects the passing of the eddy through its magnetic field as a significant perturbation in the force signal. The flow rate is estimated from the time span between the perturbations in the two force signals. In this paper, time-of-flight LFV technique is demonstrated experimentally for the case of liquid metal flow in a closed rectangular duct loop that is driven by an electromagnetic pump. A liquid metal alloy of gallium (Ga), indium (In) and tin (Sn)—GaInSn—is used as the working fluid. In contrast to prior works, for the first time, three-dimensional strain gauge force sensors were used for measuring Lorentz force to investigate the effect of flow disturbances in different directions for flow measurements by the time-of-flight LFV method. A prototype time-of-flight LFV flowmeter is developed, the operation of which in laboratory conditions is characterised by different experiments.

  15. Implementation of a new type of time-of-flight laser anemometer

    NASA Technical Reports Server (NTRS)

    Wernet, M. P.; Edwards, R. V.

    1986-01-01

    A new time-of-flight (TOF) laser anemometer system utilizing a spatial lead-lag filter for bipolar pulse generation has been constructed and tested. This new TOF has been modified to enable measurements in turbulent flows near walls. Good results have been obtained as close as 100 microns from a surface, with a 140-mm focal length final lens. Lading's theory for the behavior of the measurement variance has been confirmed for this configuration.

  16. Parameters’ Covariance in Neutron Time of Flight Analysis – Explicit Formulae

    SciTech Connect

    Odyniec, M.; Blair, J.

    2014-12-01

    We present here a method that estimates the parameters’ variance in a parametric model for neutron time of flight (NToF). The analytical formulae for parameter variances, obtained independently of calculation of parameter values from measured data, express the variances in terms of the choice, settings, and placement of the detector and the oscilloscope. Consequently, the method can serve as a tool in planning a measurement setup.

  17. The time-of-flight spectrometer with cold neutrons at the FRM-II

    NASA Astrophysics Data System (ADS)

    Zirkel, A.; Roth, S.; Schneider, W.; Neuhaus, J.; Petry, W.

    2000-03-01

    We are presenting a design study of the new cold-time-of-flight spectrometer to be built at the FRM-II. Monte Carlo techniques were used to optimize the flux at the sample position and to calculate the elastic energy resolution. A doubly focusing neutron guide is used to enhance the intensity on the sample. Magnetic bearings and carbon fiber composite disks will give access to very high chopper speeds, thereby considerably increasing the overall performance of the instrument.

  18. Fully digital data acquisition system for the neutron time-of-flight spectrometer TOFOR at JET.

    PubMed

    Skiba, M; Weiszflog, M; Hjalmarsson, A; Ericsson, G; Hellesen, C; Conroy, S; Andersson-Sundén, E; Eriksson, J; Binda, F

    2012-10-01

    A prototype of a fully digital data acquisition system based on 1 Gsps 12 bit digitizers for the TOFOR fusion neutron spectrometer at JET is assessed. The prototype system enables the use of geometry-based background discrimination techniques, which are modeled, evaluated, and compared to experimental data. The experimental results are in line with the models and show a significant improvement in signal-to-background ratio in measured time-of-flight spectrum compared to the existing data acquisition system.

  19. Neutron-induced fission measurements at the time-of-flight facility nELBE

    SciTech Connect

    Kögler, T.; Junghans, A. R.; Massarczyk, R.; Schwengner, R.; Wagner, A.

    2015-05-18

    Neutron-induced fission of ²⁴²Pu is studied at the photoneutron source nELBE. The relative fast neutron fission cross section was determined using actinide fission chambers in a time-of-flight experiment. A good agreement of present nuclear data with evalua- tions has been achieved in the range of 100 keV to 10 MeV.

  20. A New Neutron Time-of-Flight Array for β-Decay Studies

    NASA Astrophysics Data System (ADS)

    Sénoville, M.; Delaunay, F.; Achouri, N. L.; Pârlog, M.; Orr, N. A.; Cano-Ott, D.; Carniol, B.; Étasse, D.; Fontbonne, C.; Fontbonne, J. M.; Gibelin, J.; Hommet, J.; Laurent, B.; Ledoux, X.; Marqués, F. M.; Martínez, T.; De Séréville, N.

    A new time-of-flight array for β-delayed neutron spectroscopy (En < 5 MeV) is being developed with the aim of improved performance compared to existing arrays. We report on the status of this development, in particular the study of the n-γ discrimination quality with digital electronics, a comparison of several organic scintillators, including new discriminating plastics, as well as the characterisation of detectors with monoenergetic neutrons to measure intrinsic efficiencies and cross-talk probabilities.

  1. Enhanced High Resolution RBS System

    SciTech Connect

    Pollock, Thomas J.; Hass, James A.; Klody, George M.

    2011-06-01

    Improvements in full spectrum resolution with the second NEC high resolution RBS system are summarized. Results for 50 A ring TiN/HfO films on Si yielding energy resolution on the order of 1 keV are also presented. Detector enhancements include improved pulse processing electronics, upgraded shielding for the MCP/RAE detector, and reduced noise generated from pumping. Energy resolution measurements on spectra front edge coupled with calculations using 0.4mStr solid angle show that beam energy spread at 400 KeV from the Pelletron registered accelerator is less than 100 eV. To improve user throughput, magnet control has been added to the automatic data collection. Depth profiles derived from experimental data are discussed. For the thin films profiled, depth resolutions were on the Angstrom level with the non-linear energy/channel conversions ranging from 100 to 200 eV.

  2. Enhanced High Resolution RBS System

    NASA Astrophysics Data System (ADS)

    Pollock, Thomas J.; Hass, James A.; Klody, George M.

    2011-06-01

    Improvements in full spectrum resolution with the second NEC high resolution RBS system are summarized. Results for 50 Å TiN/HfO films on Si yielding energy resolution on the order of 1 keV are also presented. Detector enhancements include improved pulse processing electronics, upgraded shielding for the MCP/RAE detector, and reduced noise generated from pumping. Energy resolution measurements on spectra front edge coupled with calculations using 0.4mStr solid angle show that beam energy spread at 400 KeV from the Pelletron® accelerator is less than 100 eV. To improve user throughput, magnet control has been added to the automatic data collection. Depth profiles derived from experimental data are discussed. For the thin films profiled, depth resolutions were on the Angstrom level with the non-linear energy/channel conversions ranging from 100 to 200 eV.

  3. High-resolution land topography

    NASA Astrophysics Data System (ADS)

    Massonnet, Didier; Elachi, Charles

    2006-11-01

    After a description of the background, methods of production and some scientific uses of high-resolution land topography, we present the current status and the prospect of radar interferometry, regarded as one of the best techniques for obtaining the most global and the most accurate topographic maps. After introducing briefly the theoretical aspects of radar interferometry - principles, limits of operation and various capabilities -, we will focus on the topographic applications that resulted in an almost global topographic map of the earth: the SRTM map. After introducing the Interferometric Cartwheel system, we will build on its expected performances to discuss the scientific prospects of refining a global topographic map to sub-metric accuracy. We also show how other fields of sciences such as hydrology may benefit from the products generated by interferometric radar systems. To cite this article: D. Massonnet, C. Elachi, C. R. Geoscience 338 (2006).

  4. HIRAS, high resolution IRAS images

    NASA Astrophysics Data System (ADS)

    Bontekoe, Tj. R.; Kester, D. J. M.; Wesselius, P. R.

    The IRAS Software Telescope allows everyone to obtain the state-of-the-art IRAS products (survey, pointed observations, as well as low-resolution spectra) from raw uncalibrated scan data to FITS maps and any stage in between, any size area up to five by five degree, within 24 hours response time, and without the tedious proposal and refereeing process. This is done via an electronic mail server, without manual interaction. High Resolution Images can also be made by running HIRAS, which drives the MemSys5 (Gull & Skilling 1991) maximum entropy package. Herewith a resolution of order one arc-minute, instead of the usual five arc-minutes, can be obtained.

  5. High-resolution interferometric spectrophotopolarimetry

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.

    1981-01-01

    Spectrophotopolarimetric capability can be added to a laboratory interferometer-spectrometer by use of a specially designed module described herein. With the instrument so augmented, high-resolution spectra can be obtained of the Stokes parameters of the reference beam and the beams diffusely reflected or transmitted by a sample medium of interest. For any such beam, the exponential Fourier transforms of the two interferograms obtained with a polarizer-analyzer oriented along the 0 deg and the 90 deg directions provide the spectra of I and Q, separately. Within experimental (and numerical) noise, this I spectrum should be the same as the one obtained with the polarizer removed. The remaining Stokes parameters U and V are obtained with a third interferogram recorded with the polarizer along the 45 deg direction. The complete theory of this instrument is described including the detailed analysis of the polarization-interferograms it provides.

  6. High Resolution Thermometry for EXACT

    NASA Technical Reports Server (NTRS)

    Panek, J. S.; Nash, A. E.; Larson, M.; Mulders, N.

    2000-01-01

    High Resolution Thermometers (HRTs) based on SQUID detection of the magnetization of a paramagnetic salt or a metal alloy has been commonly used for sub-nano Kelvin temperature resolution in low temperature physics experiments. The main applications to date have been for temperature ranges near the lambda point of He-4 (2.177 K). These thermometers made use of materials such as Cu(NH4)2Br4 *2H2O, GdCl3, or PdFe. None of these materials are suitable for EXACT, which will explore the region of the He-3/He-4 tricritical point at 0.87 K. The experiment requirements and properties of several candidate paramagnetic materials will be presented, as well as preliminary test results.

  7. Picosecond resolution on relativistic heavy ions' time-of-flight measurement

    NASA Astrophysics Data System (ADS)

    Ebran, A.; Taieb, J.; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

    2013-11-01

    We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment-which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron-accelerator (ELSA) at CEA-DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution.

  8. Acetazolamide challenge for three-dimensional time-of-flight MR angiography of the brain

    SciTech Connect

    Mandai, Kenji; Sueyoshi, Kenji; Fukunaga, Ryuzo; Nukada, Masaru; Ohtani, Fumio; Araki, Yutaka; Tsukaguchi, Isao; Abe, Hiroshi )

    1994-04-01

    We compared three-dimensional time-of-flight MR angiograms obtained before and after acetazolamide administration to evaluate whether use of this drug could improve visualization of small peripheral intracranial arteries and atherosclerotic stenosis. For evaluation of small peripheral arteries, 10 patients with clinical diagnosis of ischemic cerebrovascular disease and 10 healthy volunteers were investigated, and for evaluation of stenosis, another 6 patients were investigated. Vascular images were obtained by three-dimensional time-of-flight MR angiography. After a baseline scan, 17 mg/kg acetazolamide was injected intravenously and the second scan was performed 20 minutes later. Several small peripheral arteries that had not been seen on the baseline images were visible on the acetazolamide images without any augmentation of the background signals. Stenotic lesions in the main trunks of the major cerebral arteries were detected more clearly on acetazolamide images. Acetazolamide improves visualization of small peripheral intracranial arteries and sensitivity in detecting atherosclerotic stenosis in the main trunk of major cerebral artery by three-dimensional time-of-flight MR angiography without changing MR apparatus and software. 15 refs., 5 figs., 2 tabs.

  9. HRSC: High resolution stereo camera

    USGS Publications Warehouse

    Neukum, G.; Jaumann, R.; Basilevsky, A.T.; Dumke, A.; Van Gasselt, S.; Giese, B.; Hauber, E.; Head, J. W.; Heipke, C.; Hoekzema, N.; Hoffmann, H.; Greeley, R.; Gwinner, K.; Kirk, R.; Markiewicz, W.; McCord, T.B.; Michael, G.; Muller, Jan-Peter; Murray, J.B.; Oberst, J.; Pinet, P.; Pischel, R.; Roatsch, T.; Scholten, F.; Willner, K.

    2009-01-01

    The High Resolution Stereo Camera (HRSC) on Mars Express has delivered a wealth of image data, amounting to over 2.5 TB from the start of the mapping phase in January 2004 to September 2008. In that time, more than a third of Mars was covered at a resolution of 10-20 m/pixel in stereo and colour. After five years in orbit, HRSC is still in excellent shape, and it could continue to operate for many more years. HRSC has proven its ability to close the gap between the low-resolution Viking image data and the high-resolution Mars Orbiter Camera images, leading to a global picture of the geological evolution of Mars that is now much clearer than ever before. Derived highest-resolution terrain model data have closed major gaps and provided an unprecedented insight into the shape of the surface, which is paramount not only for surface analysis and geological interpretation, but also for combination with and analysis of data from other instruments, as well as in planning for future missions. This chapter presents the scientific output from data analysis and highlevel data processing, complemented by a summary of how the experiment is conducted by the HRSC team members working in geoscience, atmospheric science, photogrammetry and spectrophotometry. Many of these contributions have been or will be published in peer-reviewed journals and special issues. They form a cross-section of the scientific output, either by summarising the new geoscientific picture of Mars provided by HRSC or by detailing some of the topics of data analysis concerning photogrammetry, cartography and spectral data analysis.

  10. High resolution tomographic instrument development

    SciTech Connect

    Not Available

    1992-08-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  11. High resolution tomographic instrument development

    SciTech Connect

    Not Available

    1992-01-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  12. High resolution time interval counter

    NASA Technical Reports Server (NTRS)

    Zhang, Victor S.; Davis, Dick D.; Lombardi, Michael A.

    1995-01-01

    In recent years, we have developed two types of high resolution, multi-channel time interval counters. In the NIST two-way time transfer MODEM application, the counter is designed for operating primarily in the interrupt-driven mode, with 3 start channels and 3 stop channels. The intended start and stop signals are 1 PPS, although other frequencies can also be applied to start and stop the count. The time interval counters used in the NIST Frequency Measurement and Analysis System are implemented with 7 start channels and 7 stop channels. Four of the 7 start channels are devoted to the frequencies of 1 MHz, 5 MHz or 10 MHz, while triggering signals to all other start and stop channels can range from 1 PPS to 100 kHz. Time interval interpolation plays a key role in achieving the high resolution time interval measurements for both counters. With a 10 MHz time base, both counters demonstrate a single-shot resolution of better than 40 ps, and a stability of better than 5 x 10(exp -12) (sigma(sub chi)(tau)) after self test of 1000 seconds). The maximum rate of time interval measurements (with no dead time) is 1.0 kHz for the counter used in the MODEM application and is 2.0 kHz for the counter used in the Frequency Measurement and Analysis System. The counters are implemented as plug-in units for an AT-compatible personal computer. This configuration provides an efficient way of using a computer not only to control and operate the counters, but also to store and process measured data.

  13. High resolution tomographic instrument development

    NASA Astrophysics Data System (ADS)

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefitted greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  14. Nano liquid chromatography with hybrid quadrupole time-of-flight mass spectrometry for the determination of yessotoxin in marine phytoplankton.

    PubMed

    Ruppén Cañás, Isabel; Hamilton, Brett; Fernández Amandi, Mónica; Furey, Ambrose; James, Kevin J

    2004-11-12

    Studies of yessotoxin involving confirmation of fragmentation processes using a high-resolution orthogonal hybrid quadrupole time-of-flight (QqTOF) mass spectrometer and nanoLC hybrid quadrupole TOF MS have been undertaken. The fragmentation of YTX was studied in negative mode using nano electrospray (nanoESI) QqTOF mass spectrometry. Three major molecule-related ions were observed, [M - 2Na + H]-, [M - Na]- and [M - 2Na]2-, and fragmentation of the latter was studied in detail. This showed that product ions were formed as a consequence of charge-remote fragmentation processes that included a strong directional cleavage of the polyether rings of YTX. NanoLC coupled with QqTOF MS was used to determine YTX in small samples of the phytoplankton, Protoceratium reticulatum, by monitoring the [M - 2Na]2- ion at m/z 570. A PepMap C18 nanoLC column (75 microm x 10 cm, 100 A, 3 microm, LC Packings) was used and the solvent was acetonitrile/water (90:10 (v/v)) containing 1 mM ammonium acetate, at a flow rate of 400 nl/min, for 30 min. Calibrations obtained with YTX standard solutions were linear over four orders of magnitude, 0.75-250 ng/ml; r2 = 0.9947-0.9998. Phytoplankton cells (ca. 100-300) were picked, extracted with methanol/water (40:60), and the YTX concentration was determined over the range 0.011-0.020 ng/cell. The detection limit (3 x S/N) of this method was ca. 0.5 pg YTX on-column.

  15. (A new time of flight) Acoustic flow meter using wide band signals and adaptive beamforming techniques

    NASA Astrophysics Data System (ADS)

    Murgan, I.; Ioana, C.; Candel, I.; Anghel, A.; Ballester, J. L.; Reeb, B.; Combes, G.

    2016-11-01

    In this paper we present the result of our research concerning the improvement of acoustic time of flight flow metering for water pipes. Current flow meters are based on the estimation of direct time of flight by matched filtering of the received and emitted signals by acoustic transducers. Currently, narrow band signals are used, as well as a single emitter/receptor transducer configuration. Although simple, this configuration presents a series of limitations such as energy losses due to pipe wall/water interface, pressure/flow transients, sensitivity to flow induced vibrations, acoustic beam deformations and shift due to changes in flow velocity and embedded turbulence in the flow. The errors associated with these limitations reduce the overall robustness of existing flow meters, as well as the measured flow rate range and lower accuracy. In order to overcome these limitations, two major innovations were implemented at the signal processing level. The first one concerns the use of wide band signals that optimise the power transfer throughout the acoustic path and also increase the number of velocity/flow readings per second. Using wide band signals having a high duration-bandwidth product increases the precision in terms of time of flight measurements and, in the same time, improves the system robustness. The second contribution consists in the use of a multiple emitter - multiple receivers configuration (for one path) in order to compensate the emitted acoustic beam shift, compensate the time of flight estimation errors and thus increase the flow meter's robustness in case of undesired effects such as the “flow blow” and transient/rapid flow rate/velocity changes. Using a new signal processing algorithm that take advantage of the controlled wide band content coming from multiple receivers, the new flow meters achieves a higher accuracy in terms of flow velocity over a wider velocity range than existing systems. Tests carried out on real scale experimental

  16. Submicron aerosol analysis and organic source apportionment in an urban atmosphere in Pearl River Delta of China using high-resolution aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    He, Ling-Yan; Huang, Xiao-Feng; Xue, Lian; Hu, Min; Lin, Yun; Zheng, Jun; Zhang, Renyi; Zhang, Yuan-Hang

    2011-06-01

    The Pearl River Delta (PRD) region in South China is one of the most economically developed regions in China while also noted for its severe air pollution, especially in the urban environments. In order to understand in depth the aerosol chemistry and the emission sources in PRD, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in the Hong Kong-Shenzhen metropolitan area between 25 October and 2 December 2009. Ten minute-resolved measurement data were analyzed, and an average mass concentration of 44.5 ± 34.0 μg m-3 was calculated for the entire campaign. On average, organic matter was the most abundant PM1 component accounting for 39.7% of the total mass, followed by sulfate (24.5%), black carbon (measured by aethalometer, 14.0%), ammonium (10.2%), nitrate (10.0%), and chloride (1.6%). Moreover, organic matter comprised an increasing fraction of the PM1 loading as the PM1 loading increased, denoting its key role in particulate pollution in this region. Calculations of organic elemental composition based on the high-resolution organic mass spectra obtained indicated that C, H, O, and N on average contributed 33.8%, 55.1%, 10.2%, and 0.9%, respectively, to the total atomic numbers of organic aerosol (OA), which corresponded to an OM/OC ratio (the ratio of organic matter mass/organic carbon mass) of 1.57 ± 0.08. Positive matrix factorization analysis was then conducted on the high-resolution organic mass spectral data set. Four OA components were identified, including a hydrocarbon-like (HOA), a biomass burning (BBOA), and two oxygenated (LV-OOA and SV-OOA) components, which on average accounted for 29.5%, 24.1%, 18.8%, and 27.6%, respectively, of the total organic mass. The HOA was found to have contributions from both fossil fuel combustion and cooking emissions, while the BBOA was well correlated with acetonitrile, a known biomass burning marker. The LV-OOA and SV-OOA corresponded to more aged and

  17. High resolution imaging at Palomar

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    1992-01-01

    For the last two years we have embarked on a program of understanding the ultimate limits of ground-based optical imaging. We have designed and fabricated a camera specifically for high resolution imaging. This camera has now been pressed into service at the prime focus of the Hale 5 m telescope. We have concentrated on two techniques: the Non-Redundant Masking (NRM) and Weigelt's Fully Filled Aperture (FFA) method. The former is the optical analog of radio interferometry and the latter is a higher order extension of the Labeyrie autocorrelation method. As in radio Very Long Baseline Interferometry (VLBI), both these techniques essentially measure the closure phase and, hence, true image construction is possible. We have successfully imaged binary stars and asteroids with angular resolution approaching the diffraction limit of the telescope and image quality approaching that of a typical radio VLBI map. In addition, we have carried out analytical and simulation studies to determine the ultimate limits of ground-based optical imaging, the limits of space-based interferometric imaging, and investigated the details of imaging tradeoffs of beam combination in optical interferometers.

  18. High-resolution infrared imaging

    NASA Astrophysics Data System (ADS)

    Falco, Charles M.

    2010-08-01

    The hands and mind of an artist are intimately involved in the creative process of image formation, intrinsically making paintings significantly more complex than photographs to analyze. In spite of this difficulty, several years ago the artist David Hockney and I identified optical evidence within a number of paintings that demonstrated artists began using optical projections as early as c1425 - nearly 175 years before Galileo - as aids for producing portions of their images. In the course of our work, Hockney and I developed insights that I have been applying to a new approach to computerized image analysis. Recently I developed and characterized a portable high resolution infrared for capturing additional information from paintings. Because many pigments are semi-transparent in the IR, in a number of cases IR photographs ("reflectograms") have revealed marks made by the artists that had been hidden under paint ever since they were made. I have used this IR camera to capture photographs ("reflectograms") of hundreds of paintings in over a dozen museums on three continents and, in some cases, these reflectograms have provided new insights into decisions the artists made in creating the final images that we see in the visible.

  19. High resolution auditory perception system

    NASA Astrophysics Data System (ADS)

    Alam, Iftekhar; Ghatol, Ashok

    2005-04-01

    Blindness is a sensory disability which is difficult to treat but can to some extent be helped by artificial aids. The paper describes the design aspects of a high resolution auditory perception system, which is designed on the principle of air sonar with binaural perception. This system is a vision substitution aid for enabling blind persons. The blind person wears ultrasonic eyeglasses which has ultrasonic sensor array embedded on it. The system has been designed to operate in multiresolution modes. The ultrasonic sound from the transmitter array is reflected back by the objects, falling in the beam of the array and is received. The received signal is converted to a sound signal, which is presented stereophonically for auditory perception. A detailed study has been done as the background work required for the system implementation; the appropriate range analysis procedure, analysis of space-time signals, the acoustic sensors study, amplification methods and study of the removal of noise using filters. Finally the system implementation including both the hardware and the software part of it has been described. Experimental results on actual blind subjects and inferences obtained during the study have also been included.

  20. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  1. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  2. High resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Loudin, Jim; Dinyari, Rostam; Huie, Phil; Butterwick, Alex; Peumans, Peter; Palanker, Daniel

    2009-02-01

    Electronic retinal prostheses seek to restore sight in patients with retinal degeneration by delivering pulsed electric currents to retinal neurons via an array of microelectrodes. Most implants use inductive or optical transmission of information and power to an intraocular receiver, with decoded signals subsequently distributed to retinal electrodes through an intraocular cable. Surgical complexity could be minimized by an "integrated" prosthesis, in which both power and data are delivered directly to the stimulating array without any discrete components or cables. We present here an integrated retinal prosthesis system based on a photodiode array implant. Video frames are processed and imaged onto the retinal implant by a video goggle projection system operating at near-infrared wavelengths (~ 900 nm). Photodiodes convert light into pulsed electric current, with charge injection maximized by specially optimized series photodiode circuits. Prostheses of three different pixel densities (16 pix/mm2, 64 pix/mm2, and 256 pix/mm2) have been designed, simulated, and prototyped. Retinal tissue response to subretinal implants made of various materials has been investigated in RCS rats. The resulting prosthesis can provide sufficient charge injection for high resolution retinal stimulation without the need for implantation of any bulky discrete elements such as coils or tethers. In addition, since every pixel functions independently, pixel arrays may be placed separately in the subretinal space, providing visual stimulation to a larger field of view.

  3. Evaluation of Advanced Bionics high resolution mode.

    PubMed

    Buechner, Andreas; Frohne-Buechner, Carolin; Gaertner, Lutz; Lesinski-Schiedat, Anke; Battmer, Rolf-Dieter; Lenarz, Thomas

    2006-07-01

    The objective of this paper is to evaluate the advantages of the Advanced Bionic high resolution mode for speech perception, through a retrospective analysis. Forty-five adult subjects were selected who had a minimum experience of three months' standard mode (mean of 10 months) before switching to high resolution mode. Speech perception was tested in standard mode immediately before fitting with high resolution mode, and again after a maximum of six months high resolution mode usage (mean of two months). A significant improvement was found, between 11 and 17%, depending on the test material. The standard mode preference does not give any indication about the improvement when switching to high resolution. Users who are converted within any study achieve a higher performance improvement than those converted in the clinical routine. This analysis proves the significant benefits of high resolution mode for users, and also indicates the need for guidelines for individual optimization of parameter settings in a high resolution mode program.

  4. Fully automatic and precise data analysis developed for time-of-flight mass spectrometry.

    PubMed

    Meyer, Stefan; Riedo, Andreas; Neuland, Maike B; Tulej, Marek; Wurz, Peter

    2017-09-01

    Scientific objectives of current and future space missions are focused on the investigation of the origin and evolution of the solar system with the particular emphasis on habitability and signatures of past and present life. For in situ measurements of the chemical composition of solid samples on planetary surfaces, the neutral atmospheric gas and the thermal plasma of planetary atmospheres, the application of mass spectrometers making use of time-of-flight mass analysers is a technique widely used. However, such investigations imply measurements with good statistics and, thus, a large amount of data to be analysed. Therefore, faster and especially robust automated data analysis with enhanced accuracy is required. In this contribution, an automatic data analysis software, which allows fast and precise quantitative data analysis of time-of-flight mass spectrometric data, is presented and discussed in detail. A crucial part of this software is a robust and fast peak finding algorithm with a consecutive numerical integration method allowing precise data analysis. We tested our analysis software with data from different time-of-flight mass spectrometers and different measurement campaigns thereof. The quantitative analysis of isotopes, using automatic data analysis, yields results with an accuracy of isotope ratios up to 100 ppm for a signal-to-noise ratio (SNR) of 10(4) . We show that the accuracy of isotope ratios is in fact proportional to SNR(-1) . Furthermore, we observe that the accuracy of isotope ratios is inversely proportional to the mass resolution. Additionally, we show that the accuracy of isotope ratios is depending on the sample width Ts by Ts(0.5) . Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Quasi-dynamic mode of nanomembranes for time-of-flight mass spectrometry of proteins

    NASA Astrophysics Data System (ADS)

    Park, Jonghoo; Kim, Hyunseok; Blick, Robert H.

    2012-03-01

    Mechanical resonators realized on the nano-scale by now offer applications in mass-sensing of biomolecules with extraordinary sensitivity. The general idea is that perfect mechanical biosensors should be of extremely small size to achieve zeptogram sensitivity in weighing single molecules similar to a balance. However, the small scale and long response time of weighing biomolecules with a cantilever restrict their usefulness as a high-throughput method. Commercial mass spectrometry (MS) such as electro-spray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-MS are the gold standards to which nanomechanical resonators have to live up to. These two methods rely on the ionization and acceleration of biomolecules and the following ion detection after a mass selection step, such as time-of-flight (TOF). Hence, the spectrum is typically represented in m/z, i.e. the mass to ionization charge ratio. Here, we describe the feasibility and mass range of detection of a new mechanical approach for ion detection in time-of-flight mass spectrometry, the principle of which is that the impinging ion packets excite mechanical oscillations in a silicon nitride nanomembrane. These mechanical oscillations are henceforth detected via field emission of electrons from the nanomembrane. Ion detection is demonstrated in MALDI-TOF analysis over a broad range with angiotensin, bovine serum albumin (BSA), and an equimolar protein mixture of insulin, BSA, and immunoglobulin G (IgG). We find an unprecedented mass range of operation of the nanomembrane detector.

  6. High-resolution slug testing.

    PubMed

    Zemansky, G M; McElwee, C D

    2005-01-01

    The hydraulic conductivity (K) variation has important ramifications for ground water flow and the transport of contaminants in ground water. The delineation of the nature of that variation can be critical to complete characterization of a site and the planning of effective and efficient remedial measures. Site-specific features (such as high-conductivity zones) need to be quantified. Our alluvial field site in the Kansas River valley exhibits spatial variability, very high conductivities, and nonlinear behavior for slug tests in the sand and gravel aquifer. High-resolution, multilevel slug tests have been performed in a number of wells that are fully screened. A general nonlinear model based on the Navier-Stokes equation, nonlinear frictional loss, non-Darcian flow, acceleration effects, radius changes in the wellbore, and a Hvorslev model for the aquifer has been used to analyze the data, employing an automated processing system that runs within the Excel spreadsheet program. It is concluded that slug tests can provide the necessary data to identify the nature of both horizontal and vertical K variation in an aquifer and that improved delineation or higher resolution of K structure is possible with shorter test intervals. The gradation into zones of higher conductivity is sharper than seen previously, and the maximum conductivity observed is greater than previously measured. However, data from this project indicate that well development, the presence of fines, and the antecedent history of the well are important interrelated factors in regard to slug-test response and can prevent obtaining consistent results in some cases.

  7. Resolving multipath interference in time-of-flight imaging via modulation frequency diversity and sparse regularization.

    PubMed

    Bhandari, Ayush; Kadambi, Achuta; Whyte, Refael; Barsi, Christopher; Feigin, Micha; Dorrington, Adrian; Raskar, Ramesh

    2014-03-15

    Time-of-flight (ToF) cameras calculate depth maps by reconstructing phase shifts of amplitude-modulated signals. For broad illumination of transparent objects, reflections from multiple scene points can illuminate a given pixel, giving rise to an erroneous depth map. We report here a sparsity-regularized solution that separates K interfering components using multiple modulation frequency measurements. The method maps ToF imaging to the general framework of spectral estimation theory and has applications in improving depth profiles and exploiting multiple scattering.

  8. Waveform-Sampling Electronics for a Whole-Body Time-of-Flight PET Scanner

    PubMed Central

    Ashmanskas, W. J.; LeGeyt, B. C.; Newcomer, F. M.; Panetta, J. V.; Ryan, W. A.; Van Berg, R.; Wiener, R. I.; Karp Fellow, J. S.

    2014-01-01

    Waveform sampling is an appealing technique for instruments requiring precision time and pulse-height measurements. Sampling each PMT waveform at oscilloscope-like rates of several gigasamples per second enables one to process PMT signals digitally, which in turn makes it straightforward to optimize timing resolution and amplitude (energy and position) resolution in response to calibration effects, pile-up effects, and other systematic sources of waveform variation. We describe a system design and preliminary implementation that neatly maps waveform-sampling technology onto the LaPET prototype whole-body time-of-flight PET scanner that serves as the platform for testing this new technology. PMID:25484379

  9. Calibration of time of flight detectors using laser-driven neutron source

    NASA Astrophysics Data System (ADS)

    Mirfayzi, S. R.; Kar, S.; Ahmed, H.; Krygier, A. G.; Green, A.; Alejo, A.; Clarke, R.; Freeman, R. R.; Fuchs, J.; Jung, D.; Kleinschmidt, A.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.

    2015-07-01

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  10. Biomark/Organic Analysis with Time-of-Flight Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Waite, J. Hunter, Jr.

    2004-01-01

    The concept of a Comprehensive 2-Dimensional Gas Chromatography coupled with Time-of-Flight Mass Spectrometry (GCxGC-TOWS) for the analysis of organic compounds has been proven with commercially available instrumentation (LECO Corp). The performance of a GCxGC instrument has been characterized in various stages using two independent breadboard systems. The GCxGC separation systems, including the thermal modulator, have been miniaturized to the size of a benchtop configuration. One breadboard system employs a Flame Ionization Detector (FID), whereas the second breadboard system employs a Time-of-Fight mass spectrometer (TOFWS) as a detection system.

  11. Time-of-flight detection of ultra-cold atoms using resonant frequency modulation imaging.

    PubMed

    Hardman, K S; Wigley, P B; Everitt, P J; Manju, P; Kuhn, C C N; Robins, N P

    2016-06-01

    Resonant frequency modulation imaging is used to detect free falling ultra-cold atoms. A theoretical comparison of fluorescence imaging (FI) and frequency modulation imaging (FMI) is made, indicating that for low optical depth clouds, FMI accomplished a higher signal-to-noise ratio under conditions necessary for a 200 μm spatially resolved atom interferometer. A 750 ms time-of-flight measurement reveals near atom shot-noise limited number measurements of 2×106 Bose-condensed Rb87 atoms. The detection system is applied to high precision spinor BEC based atom interferometer.

  12. A composition analyzer for microparticles using a spark ion source. [using time of flight spectrometers

    NASA Technical Reports Server (NTRS)

    Auer, S. O.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the element of both detector and particle materials. The total extracted ion currents was typically 10A within a period of 100ns, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes, or by nuclear bomb explosions.

  13. Imaging time-of-flight secondary ion mass spectrometry of solid-phase peptide syntheses.

    PubMed

    Aubagnac, J L; Enjalbal, C; Drouot, C; Combarieu, R; Martinez, J

    1999-07-01

    Imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) of solid-phase peptide syntheses carried out by the Merrifield and Sheppard strategies is described. Mixtures of resin beads mixed at random from batch syntheses or obtained in combinatorial chemistry by the mix and split technique, where each bead is functionalized by a unique peptide, were analyzed directly without any chemical cleavage of the growing chains to assess the nature of the growing structure on any bead of the mixture without its isolation.

  14. A 3D scanning device for architectural survey based on time-of-flight technology

    NASA Astrophysics Data System (ADS)

    Fontana, Raffaella; Gambino, Maria Chiara; Gianfrate, Gabriella; Greco, Marinella; Pampaloni, Enrico; Pezzati, Luca

    2004-09-01

    This work is intended to show the results of a few architectural and archaeological surveys realized by means of a 3D scanning device, based on TOF (Time-Of-Flight) technology. The instrument was set up by the Art Diagnostic Group of the National Institute for Applied Optics (INOA) and it is composed by a high precision scanning system equipped with a commercial low-cost distance-meter. This device was projected in order to provide the following characteristics: reliability, good accuracy and compatibility with other systems and it is devoted to applications in Cultural Heritage field.

  15. Quantum time-of-flight measurements: Kicked clock versus continuous clock

    SciTech Connect

    Alonso, Daniel; Sala Mayato, R.; Muga, J.G.

    2003-03-01

    The measurement of time durations or instants of occurrence of events has been frequently modeled 'operationally' by coupling the system of interest to a ''clock.'' According to several of these models, the operational approach is limited at low energies because the perturbation of the clock does not allow to reproduce accurately the corresponding ideal time quantity, defined for the system in isolation. We show that, for a time-of-flight measurement model that can be set to measure dwell or arrival times, these limitations may be overcome by extending the range of energies where the clock works properly using pulsed couplings rather than continuous ones.

  16. Interaction of solar wind ions with thin carbon foils: Calibration of time-of-flight spectrometers

    NASA Astrophysics Data System (ADS)

    Gonin, M.; Buergi, Alfred; Oetliker, M.; Bochsler, P.

    1992-11-01

    With the KAFKA (German acronym for carbon foils collisions analyzer) experiment, charge exchange, energy loss and angular scattering of solar wind ions in thin (1 to 10 microg/sq cm) carbon foils, are studied. Such foils are extensively used in time of flight mass spectrometry. So far, the properties of H, He, B, C, N, O, F, Ne, Na, Mg, Al, Si, S, Cl, Ar, K, Ti, Fe, and Ni and in the 0.5 to 5 keV/u energy range have been investigated.

  17. Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

    PubMed

    Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

    2012-10-01

    A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

  18. Combined distance-of-flight and time-of-flight mass spectrometer

    DOEpatents

    Enke, Christie G; Ray, Steven J; Graham, Alexander W; Hieftje, Gary M; Barinaga, Charles J; Koppenaal, David W

    2014-02-11

    A combined distance-of-flight mass spectrometry (DOFMS) and time-of-flight mass spectrometry (TOFMS) instrument includes an ion source configured to produce ions having varying mass-to-charge ratios, a first detector configured to determine when each of the ions travels a predetermined distance, a second detector configured to determine how far each of the ions travels in a predetermined time, and a detector extraction region operable to direct portions of the ions either to the first detector or to the second detector.

  19. Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies

    NASA Technical Reports Server (NTRS)

    Gulcicek, Erol E.; Boyle, James G.

    1993-01-01

    Dead time effects in chevron configured dual microchannel plates (MCPs) are investigated. Response times are determined experimentally for one chevron-configured dual MCP-type detector and two discrete dynode-type electron multipliers with 16 and 23 resistively divided stages. All of these detectors are found to be suitable for time-of-flight mass spectrometry (TOF MS), yielding 3-6-ns (FWHM) response times triggered on a single ion pulse. It is concluded that, unless there are viable solutions to overcome dead time disadvantages for continuous dynode detectors, suitable discrete dynode detectors for TOF MS appear to have a significant advantage for high repetition rate operation.

  20. Solid Phase Microextraction and Miniature Time-of-Flight Mass Spectrometer

    SciTech Connect

    Hiller, j.m.

    1999-01-26

    A miniature mass spectrometer, based on the time-of-flight principle, has been developed for the detection of chemical warfare agent precursor molecules. The instrument, with minor modifications, could fulfill many of the needs for sensing organic molecules in various Defense Programs, including Enhanced Surveillance. The basic footprint of the instrument is about that of a lunch box. The instrument has a mass range to about 300, has parts-per-trillion detection limits, and can return spectra in less than a second. The instrument can also detect permanent gases and is especially sensitive to hydrogen. In volume, the device could be manufactured for under $5000.

  1. Calibration of time of flight detectors using laser-driven neutron source

    SciTech Connect

    Mirfayzi, S. R.; Kar, S. Ahmed, H.; Green, A.; Alejo, A.; Jung, D.; Krygier, A. G.; Freeman, R. R.; Clarke, R.; Fuchs, J.; Vassura, L.; Kleinschmidt, A.; Roth, M.; Morrison, J. T.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Oliver, M.; Zepf, M.; Borghesi, M.

    2015-07-15

    Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

  2. Theory and operation of a three-gate time-of-flight velocity analyzer

    NASA Technical Reports Server (NTRS)

    Martus, K. E.; Orient, O. J.; Hodges, R. R.; Chutjian, A.

    1993-01-01

    Theoretical considerations and test results are presented for a new-type velocity analyzer for incident fast neutral particles, positive ions, and negative ions. Velocity analysis is carried out by means of a pulsed, three-gate time-of-flight (TOF) technique capable of eliminating alias velocities (harmonics) to sixth order. In addition the design and operation are presented of a four-element ion lens system, with small spherical and chromatic aberrations, suitable for interfacing a large-diameter ion beam from the TOF section with a subsequent mass analyzer.

  3. Effect of electron beam pulse width on time-of-flight spectra

    NASA Technical Reports Server (NTRS)

    Misakian, M.; Mumma, M. J.

    1974-01-01

    A simple but useful formula describing the effect of electron gun pulse width on the time of flight (TOF) spectra measured in translational spectroscopy experiments is developed. An approximately monoenergetic pulsed electrostatically focused electron beam traverses a scattering cell filled with a Maxwellian gas. Inelastic electron collisions with the gas produce metastable particles, ions, scattered electrons, and photons which then pass through a collimating slit system at right angles to the electron beam. TOF techniques are used to separate the photon signal from the metastable particle signal and to measure the TOF distribution of the metastable species.

  4. Effect of trapped ions in a gated time-of-flight apparatus

    NASA Technical Reports Server (NTRS)

    Martus, K. E.; Orient, O. J.; Chutjian, A.

    1993-01-01

    A three-mesh gate is used in a time-of-flight (TOF) apparatus to analyze the velocity of positive ions. Test results and a theoretical description are presented of an effect arising from trapping ions between meshes of a two-gate TOF velocity analyzer. The entrapped ions produce a side peak in the TOF spectra corresponding to faster ions. The onset and relative height of the side peak is dependent on the gating voltage and risetime of the pulsing electronics, while the relative intensity depends upon the velocity being sampled and the ratio of the gate width to duration.

  5. TIME-OF-FLIGHT MASS MEASUREMENTS AND THEIR IMPORTANCE FOR NUCLEAR ASTROPHYSICS

    SciTech Connect

    Matos, M.; Shapira, Dan

    2009-01-01

    Atomic masses play an important role in nuclear astrophysics. The lack of experimental values for nuclides of interest has triggered a rapid development of new mass measurement devices around the world, including Time-of-Flight (TOF) mass measurements offering an access to the most exotic nuclides. Recently, the TOF-B rho technique that includes a position measurement for magnetic rigidity correction has been implemented at the NSCL. An experiment with a similar TOF-B rho technique is approved and planned at the next generation radioactive beam facility (RIBF) at RIKEN.

  6. Electron pair emission detected by time-of-flight spectrometers: Recent progress

    SciTech Connect

    Huth, Michael; Schumann, Frank O.; Chiang, Cheng-Tien; Trützschler, Andreas; Kirschner, Jürgen; Widdra, Wolf

    2014-02-10

    We present results for electron coincidence spectroscopy using two time-of-flight (ToF) spectrometers. Excited by electron impact, the energy and momentum distribution of electron pairs emitted from the Cu(111) surface are resolved and a spectral feature related to the Shockley surface state is identified. By combining the two ToF spectrometers with a high-order harmonic generation light source, we demonstrate double photoemission spectroscopy in the laboratory that required synchrotron radiation in the past. Utilizing this setup, we report results for (γ,2e) on NiO(001) on Ag(001) excited with light at 30 eV photon energy.

  7. Time-of-flight velocity analysis of atomic and molecular beams

    NASA Technical Reports Server (NTRS)

    Hagena, O. F.; Varma, A. K.

    1968-01-01

    Conditions required for resolving a given beam speed distribution were evaluated by calculating the time-of-flight (TOF) signal for a finite open time of the beam shutter. Design criteria for a beam chopper and detection system are discussed in terms of the resolution, the range of speeds to be measured, and the optimum signal to noise ratio. A TOF system for detection of high intensity molecular beams with large speed ratios, as well as for low intensity scattered beams, is described. Experimental results are presented.

  8. Use of a large time-compensated scintillation detector in neutron time-of-flight measurements

    DOEpatents

    Goodman, Charles D.

    1979-01-01

    A scintillator for neutron time-of-flight measurements is positioned at a desired angle with respect to the neutron beam, and as a function of the energy thereof, such that the sum of the transit times of the neutrons and photons in the scintillator are substantially independent of the points of scintillations within the scintillator. Extrapolated zero timing is employed rather than the usual constant fraction timing. As a result, a substantially larger scintillator can be employed that substantially increases the data rate and shortens the experiment time.

  9. A Low-cost, Lightweight, and Miniaturized Time-of-flight Mass Spectrometer (TOFMS)

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.

    1993-01-01

    Time-of-flight mass spectrometers (TOFMS) are commonly used for mass analysis and for the measurement of energy distributions of charged particles. For achieving high mass and energy resolution these instruments generally comprise long flight tubes, often as long as a few meters. This necessitates high voltages and a very clean environment. These requirements make them bulky and heavy. We have developed an instrument and calibration techniques that are based on the design principles of TOFMS. However, instead of one long flight tube it consists of a series of cylindrical electrostatic lenses that confine ions under study along the axis of the flight tube.

  10. A silicon photomultiplier readout for time of flight neutron spectroscopy with gamma-ray detectors.

    PubMed

    Pietropaolo, A; Gorini, G; Festa, G; Andreani, C; De Pascale, M P; Reali, E; Grazzi, F; Schooneveld, E M

    2009-09-01

    The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of gamma-detection based on the new device.

  11. Analysis of the neutron time-of-flight spectra from inertial confinement fusion experiments

    DOE PAGES

    Hatarik, R.; Sayre, D. B.; Caggiano, J. A.; ...

    2015-11-12

    For a long time, neutron time-of-flight diagnostics been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d+t→n+α (DT) and d+d→n+³He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, which is also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (Tion) and cold fuel areal density. We explain such novel methodologies used to determine neutron yield, apparent Tion and DSR.

  12. Integration of neutron time-of-flight single-crystal Bragg peaks in reciprocal space

    SciTech Connect

    Schultz, Arthur J; Joergensen, Mads; Wang, Xiaoping; Mikkelson, Ruth L; Mikkelson, Dennis J; Lynch, Vickie E; Peterson, Peter F; Green, Mark L; Hoffmann, Christina

    2014-01-01

    The intensity of single crystal Bragg peaks obtained by mapping neutron time-of-flight event data into reciprocal space and integrating in various ways are compared. These include spherical integration with a fixed radius, ellipsoid fitting and integrating of the peak intensity and one-dimensional peak profile fitting. In comparison to intensities obtained by integrating in real detector histogram space, the data integrated in reciprocal space results in better agreement factors and more accurate atomic parameters. Furthermore, structure refinement using integrated intensities from one-dimensional profile fitting is demonstrated to be more accurate than simple peak-minus-background integration.

  13. The sTOF, a Favorable Geometry for a Time-of-Flight Analyzer

    NASA Astrophysics Data System (ADS)

    Murphy, Daniel M.

    2017-02-01

    A new geometry for the flight region in a time-of-flight mass spectrometer is presented. It consists of two opposing electrostatic sectors of about 255° each and straight sections with a length appropriate to the turns. The resulting geometry folds into a compact space. The first-order aberrations for position, angle, and energy are all zero. The transverse focusing properties are also excellent. For an energetic, high-divergence ion source such as laser ablation, the sTOF has higher resolution and ion transmission than a reflectron of similar physical size.

  14. Note: A novel dual-channel time-of-flight mass spectrometer for photoelectron imaging spectroscopy

    SciTech Connect

    Qin Zhengbo; Wu Xia; Tang Zichao

    2013-06-15

    A novel dual-channel time-of-flight mass spectrometer (D-TOFMS) has been designed to select anions in the photoelectron imaging measurements. In this instrument, the radiation laser can be triggered precisely to overlap with the selected ion cloud at the first-order space focusing plane. Compared with that of the conventional single channel TOFMS, the in situ mass selection performance of D-TOFMS is significantly improved. Preliminary experiment results are presented for the mass-selected photodetachment spectrum of F{sup -} to demonstrate the capability of the instrument.

  15. Time-of-flight compressed-sensing ultrafast photography for encrypted three-dimensional dynamic imaging

    NASA Astrophysics Data System (ADS)

    Liang, Jinyang; Gao, Liang; Hai, Pengfei; Li, Chiye; Wang, Lihong V.

    2016-02-01

    We applied compressed ultrafast photography (CUP), a computational imaging technique, to acquire three-dimensional (3D) images. The approach unites image encryption, compression, and acquisition in a single measurement, thereby allowing efficient and secure data transmission. By leveraging the time-of-flight (ToF) information of pulsed light reflected by the object, we can reconstruct a volumetric image (150 mm×150 mm×1050 mm, x × y × z) from a single camera snapshot. Furthermore, we demonstrated high-speed 3D videography of a moving object at 75 frames per second using the ToF-CUP camera.

  16. Reply to 'Comment on 'Quantum time-of-flight distribution for cold trapped atoms''

    SciTech Connect

    Ali, Md. Manirul; Home, Dipankar; Pan, Alok K.; Majumdar, A. S.

    2008-02-15

    In their comment Gomes et al. [Phys. Rev. A 77, 026101 (2008)] have questioned the possibility of empirically testable differences existing between the semiclassical time of flight distribution for cold trapped atoms and a quantum distribution discussed by us recently [Ali et al., Phys. Rev. A 75, 042110 (2007).]. We argue that their criticism is based on a semiclassical treatment having restricted applicability for a particular trapping potential. Their claim does not preclude, in general, the possibility of differences between the semiclassical calculations and fully quantum results for the arrival time distribution of freely falling atoms.

  17. Neutral particle time-of-flight analyzer for the Tandem Mirror Experiment Upgrade (TMX-U)

    SciTech Connect

    Hibbs, S.M.; Carter, M.R.; Coutts, G.W.

    1985-11-14

    We describe the design and performance of a time-of-flight (ToF) analyzer being built for installation on the east end cell of the Tandem Mirror Experiment Upgrade (TMX-U). Its primary purpose is to measure the velocity distribution of escaping charge exchange neutral particles having energies between 20 and 5000 electron volts (eV). It also enables direct determination of the thermal barrier potential when used in conjunction with the plasma potential diagnostic and the end loss ion spectrometer. In addition, it can measure the velocity distribution of passing ions leaving the central cell and of ions trapped in the thermal barrier.

  18. Optical time-of-flight spectroscopy for highly scattering materials measurements

    NASA Astrophysics Data System (ADS)

    Plucinski, Jerzy

    2003-04-01

    The paper presents benefits of optical time-of-flight spectroscopy for highly scattering materials to determine their basic optical properties (i.e. absorption coefficient, scattering coefficient, anisotropy factor and refractive index). The measurement techniques and methods of measured data analysis are presented too. The measurements were conducted for paper samples, technological liquids from paper mills and aqueous milk solutions. Picosecond semiconductor pulse lasers and fast light detectors (a streak camera and an avalanche photodiode working in Geiger mode) were used. It was shown that systems using these detectors and sources could provide measurement results that are very difficult or impossible to obtain by other measurement techniques.

  19. Time-of-Flight Flow Imaging of Two-Component Flow inside a Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Harel, Elad; Hilty, Christian; Koen, Katherine; McDonnell, Erin E.; Pines, Alex

    2007-01-01

    Here we report on using NMR imaging and spectroscopy in conjunction with time-of-flight tracking to noninvasively tag and monitor nuclear spins as they flow through the channels of a microfluidic chip. Any species with resolvable chemical-shift signatures can be separately monitored in a single experiment, irrespective of the optical properties of the fluids, thereby eliminating the need for foreign tracers. This is demonstrated on a chip with a mixing geometry in which two fluids converge from separate channels, and is generally applicable to any microfluidic device through which fluid flows within the nuclear spin-lattice relaxation time.

  20. TORCH - Cherenkov and Time-of-Flight PID Detector for the LHCb Upgrade at CERN

    NASA Astrophysics Data System (ADS)

    Föhl, K.; Brook, N.; Castillo García, L.; Conneely, T.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Milnes, J.; Piedigrossi, D.; Rademacker, J.; Ros Garcì a, A.; van Dijk, M.

    2016-05-01

    TORCH is a large-area precision time-of-flight detector, based on Cherenkov light production and propagation in a quartz radiator plate, which is read out at its edges. TORCH is proposed for the LHCb experiment at CERN to provide positive particle identification for kaons, and is currently in the Research-and-Development phase. A brief overview of the micro-channel plate photon sensor development, the custom-made electronics, and an introduction to the current test beam activities is given. Optical readout solutions are presented for the potential use of BaBar DIRC bar boxes as part of the TORCH configuration in LHCb.

  1. Analysis of the neutron time-of-flight spectra from inertial confinement fusion experiments

    SciTech Connect

    Hatarik, R.; Sayre, D. B.; Caggiano, J. A.; Phillips, T.; Eckart, M. J.; Bond, E. J.; Cerjan, C.; Grim, G. P.; Hartouni, E. P.; Knauer, J. P.; Mcnaney, J. M.; Munro, D. H.

    2015-11-12

    For a long time, neutron time-of-flight diagnostics been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d+t→n+α (DT) and d+d→n+³He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, which is also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (Tion) and cold fuel areal density. We explain such novel methodologies used to determine neutron yield, apparent Tion and DSR.

  2. Identification of micro-organisms using superconducting tunnel junctions and time-of-flight mass spectrometry

    SciTech Connect

    Benner, W H; Frank, M; Horn, J M; Labov, S E; Langry, K; Ullom, J

    1999-08-30

    We present time-of-flight measurements of biological material ejected from complete bacterial spores following laser irradiation. Ion impacts are registered on a microchannel plate and on a Superconducting Tunnel Junction (STJ) detector. We compare mass spectra obtained with the two detectors. The STJ has better sensitivity to massive ions and also measures the energy of each ion. We show evidence that spores of different bacillus species produce distinctive mass spectra and associate the observed mass peaks with coat proteins identified through ion-exchange extraction and gel electrophoresis.

  3. Time-of-flight x-ray photoconductivity of HgI/sub 2/

    SciTech Connect

    Kurtz, S.R.; Hughes, R.C.; Ortale, C.; Schnepple, W.F.

    1987-11-15

    Time-of-flight photoconductivity measurements were performed on HgI/sub 2/ using a penetrating, pulsed x-ray source, simulating the operation of photoconductive x-ray detectors. By examining a variety of HgI/sub 2/ samples, a wide range of electron and hole mobilities were observed, but in all cases hole transport was highly localized, limiting the collection of the photocarriers in HgI/sub 2/ detectors. The intrinsic photocarrier generation and recombination processes differed from classical Onsager and Langevin mechanisms observed in low-mobility photoconductors.

  4. Multi-Gap Resistive Plate - New Type of Detector for Time of Flight

    NASA Astrophysics Data System (ADS)

    Wu, J.; Wang, X. L.

    2005-04-01

    A Time-of-Flight tray with 28 6-gap MRPC modules was tested at AGS and then installed in STAR for the RHIC 2003 physics run after a series of module R&D. Results show clear identification of K/π up to 1.6 GeV/c and proton/K up to 2.9 GeV/c. In addition, electrons can be clearly identified by combining the dE/dx information from the TPC with the TOF detector.

  5. Performance Characteristics of a New Hybrid Triple Quadrupole Time-of-Flight Tandem Mass Spectrometer

    PubMed Central

    Andrews, Genna L.; Simons, Brigitte L.; Young, J. Bryce; Hawkridge, Adam M.; Muddiman, David C.

    2011-01-01

    The TripleTOF 5600 System, a hybrid triple quadrupole time-of-flight mass spectrometer, was evaluated to explore the key figures of merit in generating peptide and protein identifications which included spectral acquisition rates, data quality, proteome coverage, and biological depth. Employing a Saccharomyces cerevisiae tryptic digest, careful consideration of several performance features demonstrated that the speed of the TripleTOF contributed most to the resultant data. The TripleTOF system was operated with 8, 20, and 50 MS/MS events in an effort to compare to other MS technologies and to demonstrate the abilities of the instrument platform. PMID:21619048

  6. Ultrasonic time-of-flight shift measurements in carbon composite laminates containing matrix microcracks

    NASA Astrophysics Data System (ADS)

    Subramanian, Ajith; Dayal, Vinay; Barnard, Daniel J.

    2014-02-01

    Time-of-flight (TOF) shifts are calculated from the fundamental A0 Lamb mode using air-coupled ultrasound. The technique is applied to carbon/bismaleimide samples containing varying microcrack density along the length of the sample. The phase and group velocity reduction is inferred from the TOF shift data. The relation between group velocity and crack density is presented. Approximate microcrack densities over several segments of the sample are calculated using a simple constant thresholding algorithm applied to X-ray MicroCT data.

  7. Time-of-Flight Mass Measurements and Their Importance for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Matoš, M.; Estrade, A.; Amthor, A. M.; Bazin, D.; Becerril, A.; Elliot, T.; Famiano, M.; Gade, A.; Galaviz, D.; Lorusso, G.; Pereira, J.; Portillo, M.; Rogers, A.; Schatz, H.; Shapira, D.; Smith, E.; Stolz, A.; Wallace, M.

    2009-03-01

    Atomic masses play an important role in nuclear astrophysics. The lack of experimental values for nuclides of interest has triggered a rapid development of new mass measurement devices around the world, including Time-of-Flight (TOF) mass measurements offering an access to the most exotic nuclides. Recently, the TOF-Brho technique that includes a position measurement for magnetic rigidity correction has been implemented at the NSCL. An experiment with a similar TOF-Brho technique is approved and planned at the next generation radioactive beam facility (RIBF) at RIKEN.

  8. Stopping power measurements with the Time-of-Flight (ToF) technique

    NASA Astrophysics Data System (ADS)

    Fontana, Cristiano L.; Chen, Chien-Hung; Crespillo, Miguel L.; Graham, Joseph T.; Xue, Haizhou; Zhang, Yanwen; Weber, William J.

    2016-01-01

    A review of measurements of the stopping power of ions in matter is presented along with new measurements of the stopping powers of O, Si, Ti, and Au ions in self-supporting thin foils of SiO2, Nb2O5, and Ta2O5. A Time-of-Flight system at the Ion Beam Materials Laboratory at the University of Tennessee, Knoxville, was used in transmission geometry in order to reduce experimental uncertainties. The resulting stopping powers show good precision and accuracy and corroborate previously quoted values in the literature. New stopping data are determined.

  9. Shotgun collision-induced dissociation of peptides using a time of flight mass analyzer.

    PubMed

    Purvine, Samuel; Eppel, Jason-Thomas; Yi, Eugene C; Goodlett, David R

    2003-06-01

    Parallel collision-induced dissociation (CID) of peptides rather than serial, as is customary, results in loss of the obvious parent-fragment ion lineage available from CID on a single ion. We report proof-of-principle results suggesting the feasibility of parallel peptide CID, referred to here as shotgun CID, for protein identification when using the measured mass accuracies available from a time of flight mass analyzer and currently available search routines such as SEQUEST. Additionally, we report that parent-fragment ion lineage may be reconstructed from information encoded in the chromatographic single ion current traces of peptides.

  10. Time of flight measurement of speed of sound in air with a computer sound card

    NASA Astrophysics Data System (ADS)

    Aljalal, Abdulaziz

    2014-11-01

    A computer sound card and freely available audio editing software are used to measure accurately the speed of sound in air using the time-of-flight method. In addition to speed of sound measurement, inversion behaviour upon reflection from an open and closed end of a pipe is demonstrated. Also, it is demonstrated that the reflection at an open end of a pipe occurs slightly outside the pipe. The equipment needed is readily available to any student with access to a microphone, loudspeaker and computer.

  11. Multi-MHz time-of-flight electronic bandstructure imaging of graphene on Ir(111)

    SciTech Connect

    Tusche, C.; Goslawski, P.; Engel, D.; Jankowiak, A.; Kutnyakhov, D.; Elmers, H. J.; Chernov, S.; Wallauer, R.; Schönhense, G.; Ellguth, M.; Medjanik, K.

    2016-06-27

    In the quest for detailed spectroscopic insight into the electronic structure at solid surfaces in a large momentum range, we have developed an advanced experimental approach. It combines the 3D detection scheme of a time-of-flight momentum microscope with an optimized filling pattern of the BESSY II storage ring. Here, comprehensive data sets covering the full surface Brillouin zone have been used to study faint substrate-film hybridization effects in the electronic structure of graphene on Ir(111), revealed by a pronounced linear dichroism in angular distribution. The method paves the way to 3D electronic bandmapping with unprecedented data recording efficiency.

  12. Gallium arsenide telescope for measuring the time of flight of ionizing particles

    NASA Astrophysics Data System (ADS)

    Codino, Antonio

    1998-02-01

    An instrument made of GaAs strip detectors for measuring the time of flight has been designed and is presently under construction (LATIN detector). The GaAs detector and preamplifiers operate at the temperature of -55°C to reduce various noise sources. New methods regarding the readout system and detector layer arrangement aiming to attain an excellent time resolution are discussed. The characteristics of the GaAs sensors, the geometrical and mechanical arrangement of the detector and those of the preamplifiers are presented. The ultimate time resolution achievable by this detector in its present configuration is given.

  13. Stopping power measurements with the Time-of-Flight (ToF) technique

    DOE PAGES

    Fontana, Cristiano L.; Chen, Chien-Hung; Crespillo, Miguel L.; ...

    2015-11-10

    In our review of measurements of the stopping power of ions in matter is presented along with new measurements of the stopping powers of O, Si, Ti, and Au ions in self-supporting thin foils of SiO2, Nb2O5, and Ta2O5. Moreover, a Time-of-Flight system at the Ion Beam Materials Laboratory at the University of Tennessee, Knoxville, was used in transmission geometry in order to reduce experimental uncertainties. Finally, the resulting stopping powers show good precision and accuracy and corroborate previously quoted values in the literature. New stopping data are determined.

  14. A silicon photomultiplier readout for time of flight neutron spectroscopy with {gamma}-ray detectors

    SciTech Connect

    Pietropaolo, A.; Gorini, G.; Festa, G.; Andreani, C.; De Pascale, M. P.; Reali, E.; Grazzi, F.; Schooneveld, E. M.

    2009-09-15

    The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of {gamma}-detection based on the new device.

  15. A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

    NASA Astrophysics Data System (ADS)

    Mei, Bo; Tu, Xiaolin; Wang, Meng; Xu, Hushan; Mao, Ruishi; Hu, Zhengguo; Ma, Xinwen; Yuan, Youjin; Zhang, Xueying; Geng, Peng; Shuai, Peng; Zang, Yongdong; Tang, Shuwen; Ma, Peng; Lu, Wan; Yan, Xinshuai; Xia, Jiawen; Xiao, Guoqing; Guo, Zhongyan; Zhang, Hongbin; Yue, Ke

    2010-12-01

    A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe). The detector has been successfully used in an experiment to measure the masses of the N≈ Z≈33 nuclides near the proton drip-line. Of particular interest is the mass of 65As. A maximum detection efficiency of 70% and a time resolution of 118±8 ps (FWHM) have been achieved in the experiment. The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied. The potential of APH for Z identification has been discussed.

  16. Delayed extraction time-of-flight mass spectrometer with electron impact for PAH studies

    NASA Astrophysics Data System (ADS)

    Najeeb, P. K.; Kadhane, U.

    2017-03-01

    A time-of-flight (ToF) mass spectrometer with a pulsed electron beam as well as pulsed extraction of the recoil ions, with variable delay is reported. The effectiveness of this technique is highlighted by studying the statistical decay of mono-cations over microsecond time scales. Various details of the design and operation are discussed in the context of electron impact ionization and fragmentation of naphthalene (C10H8). The temporal behavior of acetylene (C2H2) and diacetylene (C4H2) loss is observed and compared with the associated Arrhenius decay constant, internal energy and plasmon excitation energy.

  17. A 3D profile function suitable for integration of neutron time-of-flight single crystal diffraction peaks

    NASA Astrophysics Data System (ADS)

    Gutmann, Matthias J.

    2017-03-01

    A 3D profile function is presented suitable to integrate reflections arising in time-of-flight (TOF) single crystal neutron diffraction experiments. In order to account for the large asymmetry of the peak shape in the TOF direction, a 3D Gaussian ellipsoid in the pixel (x, z) and time-of-flight coordinates is convoluted with a rising and falling exponential along the time-of-flight direction. An analytic expression is derived, making it suitable for least-squares fitting. The application of this function in detector space or reciprocal space is straightforward.

  18. Simultaneous determination of metabolic stability and identification of buspirone metabolites using multiple column fast liquid chromatography time-of-flight mass spectrometry.

    PubMed

    Nägele, Edgar; Fandino, Anabel S

    2007-07-13

    A recent trend in the drug discovery and development process is to shift the starting point of drug metabolism and pharmacokinetic (DMPK) studies to a time as early as possible in the development chain to address potential issues in parallel with the optimization of the drug's lead structure. Therefore, it is necessary to develop assay methods to determine early adsorption, distribution, metabolism and excretion (ADME) parameters like metabolic stability and metabolite identification. For metabolite identification it is of crucial importance to work with fast liquid chromatography/mass spectrometry (LC/MS) systems, which provide the necessary high throughput functionalities to handle a large number of samples in combination with high speed and high resolution chromatography as well as mass accuracy. In this study a fast two-column liquid chromatography (LC) method will be used to simultaneously determine metabolic stability and to identify metabolites of buspirone using highly accurate mass measurement by means of an electrospray time-of-flight (ESI-TOF) mass spectrometer. Whereby, the metabolic stability will be determined on a short sub-two micron column, the main metabolites will be identified in the same experiment by the automated use of a long sub-two micron column, which provides the necessary high resolution.

  19. Inorganic Salt Interference on CO2(+) in Aerodyne AMS and ACSM Organic Aerosol Composition Studies.

    PubMed

    Pieber, Simone M; El Haddad, Imad; Slowik, Jay G; Canagaratna, Manjula R; Jayne, John T; Platt, Stephen M; Bozzetti, Carlo; Daellenbach, Kaspar R; Fröhlich, Roman; Vlachou, Athanasia; Klein, Felix; Dommen, Josef; Miljevic, Branka; Jiménez, José L; Worsnop, Douglas R; Baltensperger, Urs; Prévôt, André S H

    2016-10-04

    Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO2(+) fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO2(+) signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH4NO3) causes a median CO2(+) interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P10-90 = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2-10 times enhanced interference compared to that of NH4NO3, while the ammonium sulfate ((NH4)2SO4) induced interference was 3-10 times lower. Propagation of the CO2(+) interference to other ions during standard AMS and ACSM data analysis affects the calculated OA mass, mass spectra, molecular oxygen-to-carbon ratio (O/C), and f44. The resulting bias may be trivial for most ambient data sets but can be significant for aerosol with higher inorganic fractions (>50%), e.g., for low ambient temperatures, or laboratory experiments. The large variation between instruments makes it imperative to regularly quantify this effect on individual AMS and ACSM systems.

  20. Tagging of Isobars Using Energy Loss and Time-of-flight Measurements

    SciTech Connect

    Shapira, D.

    2001-11-02

    The technique for tagging isobars in a mixed beam by measuring energy loss by time-of-flight has been tested. With this method, isobar separation should improve by allowing more energy loss (thicker absorber), but only if one can control absorber homogeneity. Measurements of beam energy toss and energy spread obtained under such conditions were shown to be close to predicted values using both collisional and charge exchange contributions to energy straggling. The calculation of energy straggling allows us to study the efficacy of this method for isobar separation when applied to different mass ranges and beam energies. Separation in a most difficult case, an analyzed beam of A = 132 isobars at energies near 3 MeV/A has been demonstrated. The time-of-flight information can be added on line as an additional tag to the data stream for events of interest. Such event by event tagging enables one to study the effect of differences in isobaric mixture in the beam on the reaction outcome even when isobar separation is not complete.

  1. Lanthanum halide scintillators for time-of-flight 3-D pet

    DOEpatents

    Karp, Joel S [Glenside, PA; Surti, Suleman [Philadelphia, PA

    2008-06-03

    A Lanthanum Halide scintillator (for example LaCl.sub.3 and LaBr.sub.3) with fast decay time and good timing resolution, as well as high light output and good energy resolution, is used in the design of a PET scanner. The PET scanner includes a cavity for accepting a patient and a plurality of PET detector modules arranged in an approximately cylindrical configuration about the cavity. Each PET detector includes a Lanthanum Halide scintillator having a plurality of Lanthanum Halide crystals, a light guide, and a plurality of photomultiplier tubes arranged respectively peripherally around the cavity. The good timing resolution enables a time-of-flight (TOF) PET scanner to be developed that exhibits a reduction in noise propagation during image reconstruction and a gain in the signal-to-noise ratio. Such a PET scanner includes a time stamp circuit that records the time of receipt of gamma rays by respective PET detectors and provides timing data outputs that are provided to a processor that, in turn, calculates time-of-flight (TOF) of gamma rays through a patient in the cavity and uses the TOF of gamma rays in the reconstruction of images of the patient.

  2. Time-of-flight Extreme Environment Diffractometer at the Helmholtz-Zentrum Berlin

    SciTech Connect

    Prokhnenko, Oleksandr Stein, Wolf-Dieter; Bleif, Hans-Jürgen; Fromme, Michael; Bartkowiak, Maciej; Wilpert, Thomas

    2015-03-15

    The Extreme Environment Diffractometer (EXED) is a new neutron time-of-flight instrument at the BER II research reactor at the Helmholtz-Zentrum Berlin, Germany. Although EXED is a special-purpose instrument, its early construction made it available for users as a general-purpose diffractometer. In this respect, EXED became one of the rare examples, where the performance of a time-of-flight diffractometer at a continuous source can be characterized. In this paper, we report on the design and performance of EXED with an emphasis on the unique instrument capabilities. The latter comprise variable wavelength resolution and wavelength band, control of the incoming beam divergence, the possibility to change the angular positions of detectors and their distance to the sample, and use of event recording and offline histogramming. These features combined make EXED easily tunable to the requirements of a particular problem, from conventional diffraction to small angle neutron scattering. The instrument performance is demonstrated by several reference measurements and user experiments.

  3. Recent Advances and Future Advances in Time-of-Flight PET

    PubMed Central

    Moses, William W.

    2007-01-01

    Simple theory predicts that the statistical noise variance in PET can be reduced by an order of magnitude by using time-of-flight (TOF) information. This reduction can be obtained by improving the coincidence timing resolution, and so would be achievable in clinical, whole body studies using with PET systems that differ little from existing cameras. The potential impact of this development is large, especially for oncology studies in large patients, where it is sorely needed. TOF PET was extensively studied in the 1980’s but died away in the 1990’s, as it was impossible to reliably achieve sufficient timing resolution without sacrificing other important PET performance aspects, such as spatial resolution and efficiency. Recent advances in technology (scintillators, photodetectors, and high speed electronics) have renewed interest in TOF PET, which is experiencing a rebirth. However, there is still much to be done, both in instrumentation development and evaluating the true benefits of TOF in modern clinical PET. This paper looks at what has been accomplished and what needs to be done before time-of-flight PET can reach its full potential. PMID:18836513

  4. Slow light and chromatic temporal dispersion in photonic crystal waveguides using femtosecond time of flight.

    PubMed

    Finlayson, C E; Cattaneo, F; Perney, N M B; Baumberg, J J; Netti, M C; Zoorob, M E; Charlton, M D B; Parker, G J

    2006-01-01

    We report time-of-flight experiments on photonic-crystal waveguide structures using optical Kerr gating of a femtosecond white-light supercontinuum. These photonic-crystal structures, based on engineered silicon-nitride slab waveguides, possess broadband low-loss guiding properties, allowing the group velocity dispersion of optical pulses to be directly tracked as a function of wavelength. This dispersion is shown to be radically disrupted by the spectral band gaps associated with the photonic-crystal periodicity. Increased time-of-flight effects, or "slowed light," are clearly observed at the edges of band gaps in agreement with two-dimensional plane-wave theoretical models of group velocity dispersion. A universal model for slow light in such photonic crystals is proposed, which shows that slow light is controlled predominantly by the detuning from, and the size of, the photonic band gaps. Slowed light observed up to time delays of approximately 1 ps, corresponds to anomalous dispersion of approximately 3.5 ps/nm per mm of the photonic crystal structure. From the decreasing intensity of time-gated slow light as a function of time delay, we estimate the characteristic losses of modes which are guided in the spectral proximity of the photonic band gaps.

  5. A constant-momentum/energy-selector time-of-flight mass spectrometer.

    PubMed

    Santacruz, C P; Håkansson, P; Barofsky, D F; Piyadasa, C K G

    2007-01-01

    A matrix assisted laser desorption/ionization time-of-flight mass spectrometer has been built with an ion source that can be operated in either constant-energy or constant-momentum acceleration modes. A decreasing electric field distribution in the ion-accelerating region makes it possible to direct ions onto a space-focal plane in either modes of operation. Ions produced in the constant-momentum mode have velocities and, thus, flight times that are linearly dependent on mass and kinetic energies that are inversely dependent on mass. The linear mass dispersion doubles mass resolving power of ions accelerated with space-focusing conditions in constant-momentum mode. The mass-dependent kinetic energy is exploited to disperse ions according to mass in a simple kinetic energy filter constructed from two closely spaced, oblique ion reflectors. Focusing velocity of ions of the same mass can substantially improve ion selection for subsequent post source decay or tandem time-of-flight analyses.

  6. Barrel time-of-flight detector for the PANDA experiment at FAIR

    NASA Astrophysics Data System (ADS)

    Gruber, L.; Brunner, S. E.; Marton, J.; Orth, H.; Suzuki, K.

    2016-07-01

    The barrel time-of-flight detector for the PANDA experiment at FAIR is foreseen as a Scintillator Tile (SciTil) Hodoscope based on several thousand small plastic scintillator tiles read-out with directly attached Silicon Photomultipliers (SiPMs). The main tasks of the system are an accurate determination of the time origin of particle tracks to avoid event mixing at high collision rates, relative time-of-flight measurements as well as particle identification in the low momentum regime. The main requirements are the use of a minimum material amount and a time resolution of σ < 100 ps. We have performed extensive optimization studies and prototype tests to prove the feasibility of the SciTil design and finalize the R&D phase. In a 2.7 GeV/c proton beam at Forschungszentrum Jülich a time resolution of about 80 ps has been achieved using SiPMs from KETEK and Hamamatsu with an active area of 3 × 3mm2. Employing the Digital Photon Counter from Philips a time resolution of about 30 ps has been reached.

  7. Glioma vessel abnormality quantification using time-of-flight MR angiography.

    PubMed

    Strumia, Maddalena; Reichardt, Wilfried; Staszewski, Ori; Heiland, Dieter Henrik; Weyerbrock, Astrid; Mader, Irina; Bock, Michael

    2016-10-01

    To differentiate between abnormal tumor vessels and regular brain vasculature using new quantitative measures in time-of-flight (TOF) MR angiography (MRA) data. In this work time-of-flight (TOF) MR angiography data are acquired in 11 glioma patients to quantify vessel abnormality. Brain vessels are first segmented with a new algorithm, efficient monte-carlo image-analysis for the location of vascular entity (EMILOVE), and are then characterized in three brain regions: tumor, normal-appearing contralateral brain, and the total brain volume without the tumor. For characterization local vessel orientation angles and the dot product between local orientation vectors are calculated and averaged in the 3 regions. Additionally, correlation with histological and genetic markers is performed. Both the local vessel orientation angles and the dot product show a statistically significant difference (p < 0.005) between tumor vessels and normal brain vasculature. Furthermore, the connection to both histology and the gene expression of the tumor can be found-here, the measures were compared to the proliferation marker Ki-67 [MIB] and genome-wide expression analysis. The results in a subgroup indicate that the dot product measure may be correlated with activated genetic pathways. It is possible to define a measure of vessel abnormality based on local vessel orientation angles which can differentiate between normal brain vasculature and glioblastoma vessels.

  8. Electric field measurement in the ionosphere using the time-of-flight technique

    SciTech Connect

    Nakamura, Masato; Hayakawa, Hajime; Tsuruda, Koichiro )

    1989-05-01

    The first successful electric field measurement in the ionosphere using the time-of-flight technique with a lithium ion beam was carried out on a S-520 sounding rocket launched from Kagoshima Space Center, Japan on January 15, 1987. The purpose of this experiment was to prove the validity of the time-of-flight technique when it is applied to the measurement of the dc electric field in the ionosphere. A time-coded ion beam was ejected from the rocket in the direction perpendicular to the Earth's magnetic field. The beam returned to the rocket twice per rocket spin when the initial beam direction was nearly perpendicular to the electric field. The electric field and the magnetic field were derived from the travel time of these return lithium ions. The accuracy of the electric field determination was {plus minus} 0.3 mV/m. The direction of the electric field was obtained from the direction of the returning ion beam after about one ion gyration. The main constituent of the measured electric field was a V {times} B field due to the rocket motion across the geomagnetic field. The ambient field was less than 1 mV/m. The magnetic field was measured with an accuracy of {plus minus} 2.7 nT in this experiment.

  9. Identification of rolling circulating tumor cells using photoacoustic time-of-flight method

    NASA Astrophysics Data System (ADS)

    Sarimollaoglu, Mustafa; Nedosekin, Dmitry A.; Galanzha, Ekaterina I.; Zharov, Vladimir P.

    2013-03-01

    Existing optical techniques for in vivo measurement of blood flow velocity are not quite applicable for determination of velocity of individual cells or nanoparticles. A time-of-flight photoacoustic (PA) technique can solve this problem by measuring the transient PA signal width, which is related to the cell velocity passing the laser beam. This technique was demonstrated in vivo using an animal (mouse) model by estimating the velocity of nanoparticles, and red and white blood cells labeled with conjugated gold nanorods (GNRs) in the bloodstream. Here we describe the features and the parameters of novel modifications to the PA time-of-flight method and its new application for real-time monitoring of circulating tumor cells (CTCs), such as B16F10 melanoma. This method provided, for the first time, identification of rolling CTCs in analogy to rolling white blood cells and CTC aggregates. Specifically, monitoring of PA signal widths from CTCs in mouse ear microvessels revealed double maxima in peak-width histograms associated with the fast moving portion of CTCs in central flow and slowly rolling CTCs in analogy to white blood cells. We also developed a two-parameter plot representing PA peak amplitude and peak widths. This method allowed identification of fast-moving individual CTCs, CTC aggregates, and rolling CTCs. The discovery of rolling CTCs in relatively large blood vessels indicates a higher probability of CTC extravasations, further increasing the possibility of metastasis through rolling mechanism in addition to mechanical capturing of CTCs in small vessels.

  10. Studying time of flight imaging through scattering media across multiple size scales (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Velten, Andreas

    2017-05-01

    Light scattering is a primary obstacle to optical imaging in a variety of different environments and across many size and time scales. Scattering complicates imaging on large scales when imaging through the atmosphere when imaging from airborne or space borne platforms, through marine fog, or through fog and dust in vehicle navigation, for example in self driving cars. On smaller scales, scattering is the major obstacle when imaging through human tissue in biomedical applications. Despite the large variety of participating materials and size scales, light transport in all these environments is usually described with very similar scattering models that are defined by the same small set of parameters, including scattering and absorption length and phase function. We attempt a study of scattering and methods of imaging through scattering across different scales and media, particularly with respect to the use of time of flight information. We can show that using time of flight, in addition to spatial information, provides distinct advantages in scattering environments. By performing a comparative study of scattering across scales and media, we are able to suggest scale models for scattering environments to aid lab research. We also can transfer knowledge and methodology between different fields.

  11. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures.

    PubMed

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A; Steuwer, Axel; Kiyanagi, Ryoji; Tremsin, Anton S; Knudsen, Erik B; Shinohara, Takenao; Willendrup, Peter K; da Silva Fanta, Alice Bastos; Iyengar, Srinivasan; Larsen, Peter M; Hanashima, Takayasu; Moyoshi, Taketo; Kadletz, Peter M; Krooß, Philipp; Niendorf, Thomas; Sales, Morten; Schmahl, Wolfgang W; Schmidt, Søren

    2017-08-25

    The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure. The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD).

  12. Estimation of optical parameters of highly scattering materials by time-of-flight spectroscopy

    NASA Astrophysics Data System (ADS)

    Plucinski, Jerzy

    2004-07-01

    Optical measurement methods are indispensable tool in biomedical research, providing invaluable information on optical properties of biological tissues. However, the application of these techniques is a big challenge, as most tissues are highly scattering materials whose optical properties cannot be measured in a straightforward way, due to multiple scattering of photons. Therefore, new optical measurement techniques and methods for highly scattering media are being developed to address this problem. One of the very promising techniques is time-of-flight spectroscopy. The paper presents problems encountered in reconstruction of basic optical parameters of tissues or other highly scattering materials from optical time-of-flight spectroscopy measurement data. To estimate the reconstruction accuracy of optical parameters (i.e. absorption coefficient, scattering coefficient, anisotropy factor and refractive index) the test data were generated by a computer program simulating light propagation in highly scattering material by Monte Carlo method. Following, a set of computer programs based on diffusion equation and optimization algorithms such as simplex method and genetic method were used to reconstruct optical parameters from the test data. Finally, by comparing reconstructed optical parameters with those used for generation of the test data, the accuracy of reconstructing algorithms it was estimated.

  13. Breath Analysis Using a Time-of-Flight Camera and Pressure Belts.

    PubMed

    Zalud, Ludek; Kotova, Marketa; Kocmanová, Petra; Dobsak, Petr; Kolarova, Jana

    2016-06-01

    The proper way of breathing is important for everyone. Healthy people often do not follow respiration until breathing problems start-during stress or during sport activity in physiological cases. More serious cases are stroke, injury, or surgery of the chest and others. So, learning to breathe correctly and/or breathing diagnosis is considerable for many reasons. Two novel methods of breath analysis suitable for diagnostics and rehabilitation are presented. The first technique utilizes pressure belts fastened to the patient's belly and chest, and the second method relies on a SwissRanger SR-4000 time-of-flight camera. The measurement principles are described together with the advantages and disadvantages of the applied techniques. The SwissRanger camera depth calibration is proposed to facilitate better results during the breath analysis. The methods are tested on a group of students to provide a comparison of their individual performances. As it was demonstrated, presented methods proved to work reliably. The method based on time-of-flight camera seems to be more suitable for diagnosis, while the method based on pressure belts is more suitable for rehabilitation and biofeedback applications.

  14. Evaluating the capability of time-of-flight cameras for accurately imaging a cyclically loaded beam

    NASA Astrophysics Data System (ADS)

    Lahamy, Hervé; Lichti, Derek; El-Badry, Mamdouh; Qi, Xiaojuan; Detchev, Ivan; Steward, Jeremy; Moravvej, Mohammad

    2015-05-01

    Time-of-flight cameras are used for diverse applications ranging from human-machine interfaces and gaming to robotics and earth topography. This paper aims at evaluating the capability of the Mesa Imaging SR4000 and the Microsoft Kinect 2.0 time-of-flight cameras for accurately imaging the top surface of a concrete beam subjected to fatigue loading in laboratory conditions. Whereas previous work has demonstrated the success of such sensors for measuring the response at point locations, the aim here is to measure the entire beam surface in support of the overall objective of evaluating the effectiveness of concrete beam reinforcement with steel fibre reinforced polymer sheets. After applying corrections for lens distortions to the data and differencing images over time to remove systematic errors due to internal scattering, the periodic deflections experienced by the beam have been estimated for the entire top surface of the beam and at witness plates attached. The results have been assessed by comparison with measurements from highly-accurate laser displacement transducers. This study concludes that both the Microsoft Kinect 2.0 and the Mesa Imaging SR4000s are capable of sensing a moving surface with sub-millimeter accuracy once the image distortions have been modeled and removed.

  15. Time-of-flight Extreme Environment Diffractometer at the Helmholtz-Zentrum Berlin.

    PubMed

    Prokhnenko, Oleksandr; Stein, Wolf-Dieter; Bleif, Hans-Jürgen; Fromme, Michael; Bartkowiak, Maciej; Wilpert, Thomas

    2015-03-01

    The Extreme Environment Diffractometer (EXED) is a new neutron time-of-flight instrument at the BER II research reactor at the Helmholtz-Zentrum Berlin, Germany. Although EXED is a special-purpose instrument, its early construction made it available for users as a general-purpose diffractometer. In this respect, EXED became one of the rare examples, where the performance of a time-of-flight diffractometer at a continuous source can be characterized. In this paper, we report on the design and performance of EXED with an emphasis on the unique instrument capabilities. The latter comprise variable wavelength resolution and wavelength band, control of the incoming beam divergence, the possibility to change the angular positions of detectors and their distance to the sample, and use of event recording and offline histogramming. These features combined make EXED easily tunable to the requirements of a particular problem, from conventional diffraction to small angle neutron scattering. The instrument performance is demonstrated by several reference measurements and user experiments.

  16. Time-of-Flight Polarized Neutron Reflectometry on PLATYPUS: Status and Future Developments

    NASA Astrophysics Data System (ADS)

    Saerbeck, T.; Cortie, D. L.; Brück, S.; Bertinshaw, J.; Holt, S. A.; Nelson, A.; James, M.; Lee, W. T.; Klose, F.

    Time-of-flight (ToF) polarized neutron reflectometry enables the detailed investigation of depth-resolved magnetic structures in thin film and multilayer magnetic systems. The general advantage of the time-of-flight mode of operation over monochromatic instruments is a decoupling of spectral shape and polarization of the neutron beam with variable resolution. Thus, a wide Q-range can be investigated using a single angle of incidence, with resolution and flux well-adjusted to the experimental requirement. Our paper reviews the current status of the polarization equipment of the ToF reflectometer PLATYPUS and presents first results obtained on stratified Ni80Fe20/α-Fe2O3 films, revealing the distribution of magnetic moments in an exchange bias system. An outlook on the future development of the PLATYPUS polarization system towards the implementation of a polarized 3He cell is presented and discussed with respect to the efficiency and high Q-coverage up to 1 Å-1 and 0.15 Å-1 in the vertical and lateral momentum transfer, respectively.

  17. The multipurpose time-of-flight neutron reflectometer “Platypus” at Australia's OPAL reactor

    NASA Astrophysics Data System (ADS)

    James, M.; Nelson, A.; Holt, S. A.; Saerbeck, T.; Hamilton, W. A.; Klose, F.

    2011-03-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ( λ=2-20 Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10 -7 are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  18. Determination of Imazaquin and its metabolite by liquid chromatography-quadrupole-time of flight tandem mass.

    PubMed

    Yao, H B; Han, G J; Liu, G X; Xie, Y; Wang, C H

    2010-08-01

    A method consisting of solvent extraction followed by liquid chromatography-quadrupole-time of flight- tandem mass spectrometry analysis was developed for the identification of Imazaquin and its metabolite. The relationships between detector response and sample concentrations showed a high degree of linearity (r > 0.998) over the range 0.03-10 microg/g. The recoveries obtained were in the acceptable range of 86%-104% between spiked. The relative standard deviation of this method was 6.4%-17.1%. A 35-day study of Imazaquin degradation was taken in agricultural soil from Binzhou, China. The degradation followed first order kinetics (C = 0.7672e(-0.0774t)), with half-life of less than 8.5 days. Investigation of the by-products from liquid chromatography-quadrupole-time of flight- tandem mass spectrometry has shown that there were four important metabolites 4-methylene-2-(quinolin-2-yl)-1H-imidazol-5(4H)-one, quinoline-3-carbaldehyde, 1-amino-2,3-dimethyl-1-oxobutan-2-ylium and 1H-[1,2]oxazino[4,5-b]quinolin-1-one in the degradation process. The accurate mass measurements error was 5 ppm in this study. The method was successfully applied to the analysis of imazaquin and its metabolite residues in soil.

  19. Fast neutron measurements at the nELBE time-of-flight facility

    NASA Astrophysics Data System (ADS)

    Junghansa, A. R.; Beyer, R.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.

    2015-05-01

    The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

  20. Structural measurements on several alamethicin peptides by the time-of-flight correlation technique

    NASA Astrophysics Data System (ADS)

    Poppe-Schriemer, N.; Ens, W.; O'Neil, J. D.; Spicer, V.; Standing, K. G.; Westmore, J. B.; Yee, A. A.

    1995-05-01

    Time-of-flight correlation methods have been used to determine the primary structure of the major component in a nonstandard preparation of alamethicins, and to give some sequence information about minor components. The peptide (MW [approximate] 2000 u) is blocked at the N terminus with an acetyl group and has a primary alcohol rather than a carboxyl group at the C terminus, so the usual wet chemical sequencing methods cannot be applied. Upon bombardment with 25 keVI- ions, the peptide, deposited on the surface of a solid target, produces both molecular ions and prompt fragment ions (i.e. ions formed at or very near the surface of the target). After acceleration, these ions may undergo metastable decay as they pass along the flight tube of a reflecting time-of-flight mass spectrometer. Measurement of the correlations between the neutral and charged daughters from these decompositions determines the decay pattern of each ion, which in turn yields definitive information about the sequence of the original peptide. All events are recorded on magnetic tape and analyzed off-line, so a single run on the spectrometer provides information on the decay of every ion produced at the target, i.e. information similar to that obtainable from a complete set of daughter ion scans on a multiple sector or triple quadrupole instrument.

  1. Pharmaceutical metabolite profiling using quadrupole/ion mobility spectrometry/time-of-flight mass spectrometry.

    PubMed

    Chan, Eric C Y; New, Lee Sun; Yap, Chun Wei; Goh, Lin Tang

    2009-02-01

    The use of hybrid quadrupole ion mobility spectrometry time-of-flight mass spectrometry (Q/IMS/TOFMS) in the metabolite profiling of leflunomide (LEF) and acetaminophen (APAP) is presented. The IMS drift times (T(d)) of the drugs and their metabolites were determined in the IMS/TOFMS experiments and correlated with their exact monoisotopic masses and other in silico generated structural properties, such as connolly molecular area (CMA), connolly solvent-excluded volume (CSEV), principal moments of inertia along the X, Y and Z Cartesian coordinates (MI-X, MI-Y and MI-Z), inverse mobility and collision cross-section (CCS). The correlation of T(d) with these parameters is presented and discussed. IMS/TOF tandem mass spectrometry experiments (MS(2) and MS(3)) were successfully performed on the N-acetyl-p-benzoquinoneimine glutathione (NAPQI-GSH) adduct derived from the in vitro microsomal metabolism of APAP. As comparison, similar experiments were also performed using hybrid triple quadrupole linear ion trap mass spectrometry (QTRAPMS) and quadrupole time-of-flight mass spectrometry (QTOFMS). The abilities to resolve the product ions of the metabolite within the drift tube and fragment the ion mobility resolved product ions in the transfer travelling wave-enabled stacked ring ion guide (TWIG) demonstrated the potential applicability of the Q/IMS/TOFMS technique in pharmaceutical metabolite profiling.

  2. TOFPET 2: A high-performance circuit for PET time-of-flight

    NASA Astrophysics Data System (ADS)

    Di Francesco, Agostino; Bugalho, Ricardo; Oliveira, Luis; Rivetti, Angelo; Rolo, Manuel; Silva, Jose C.; Varela, Joao

    2016-07-01

    We present a readout and digitization ASIC featuring low-noise and low-power for time-of flight (TOF) applications using SiPMs. The circuit is designed in standard CMOS 110 nm technology, has 64 independent channels and is optimized for time-of-flight measurement in Positron Emission Tomography (TOF-PET). The input amplifier is a low impedance current conveyor based on a regulated common-gate topology. Each channel has quad-buffered analogue interpolation TDCs (time binning 20 ps) and charge integration ADCs with linear response at full scale (1500 pC). The signal amplitude can also be derived from the measurement of time-over-threshold (ToT). Simulation results show that for a single photo-electron signal with charge 200 (550) fC generated by a SiPM with (320 pF) capacitance the circuit has 24 (30) dB SNR, 75 (39) ps r.m.s. resolution, and 4 (8) mW power consumption. The event rate is 600 kHz per channel, with up to 2 MHz dark counts rejection.

  3. Tandem time-of-flight experiment for low energy collision studies.

    PubMed

    Sublemontier, O; Poisson, L; Pradel, P; Mestdagh, J M; Visticot, J P

    2000-02-01

    We present an experiment adapted to collisional studies of cluster ions based on a laser vaporization setup coupled to a supersonic expansion. The ions are selected in a first time-of-flight, slowed down to the desired energy, and collided in an octopolar guide. The parent and fragment ions are then reaccelerated in order to be mass analyzed in a reflectron time-of-flight. An original method for the extraction of the ion that uses a double voltage pulse, is proposed. The experiment has been applied to collisions of hydrated cobalt ions. An absolute cross section of 17 A2 for the loss of one water molecule by Co(H2O)2+ in collision with neon at a center-of-mass energy of 10 eV, has been determined, with an accuracy of 10%. The threshold for this reaction has been measured at 1.5 eV and is in good agreement with the existing literature (Dalleska et al. J. Am. Chem. Soc. 1994, 116, 3519). Ions that cannot be formed by conventional ligand exchange methods, can also be studied. As an example, the threshold for dehydration of the Co2(H2O)+ ion has been measured at 1.5 +/- 0.2 eV.

  4. Laser ionization time of flight mass spectrometer for isotope mass detection and elemental analysis of materials

    NASA Astrophysics Data System (ADS)

    Ahmed, Nasar; Ahmed, Rizwan; Umar, Z. A.; Aslam Baig, M.

    2017-08-01

    In this paper we present the construction and modification of a linear time-of-flight mass spectrometer to improve its mass resolution. This system consists of a laser ablation/ionization section based on a Q-switched Nd:YAG laser (532 nm, 500 mJ, 5 ns pulse duration) integrated with a one meter linear time-of-flight mass spectrometer coupled with an electric sector and a magnetic lens and outfitted with a channeltron electron multiplier for ion detection. The resolution of the system has been improved by optimizing the accelerating potential and inserting a magnetic lens after the extraction region. The isotopes of lithium, lead and cadmium samples have been resolved and detected in accordance with their natural abundance. The capability of the system has been further exploited to determine the elemental composition of a brass alloy, having a certified composition of zinc and copper. Our results are in excellent agreement with its certified composition. This setup is found to be extremely efficient and convenient for fast analyses of any solid sample.

  5. The CDFII time-of-flight detector and impact on beauty flavor tagging

    SciTech Connect

    C. Grozis et al.

    2002-12-03

    Following the successful RunI from 1992 to 1996, the CDF detector has undergone a major upgrade [1] for the RunII which begun in March 2001. The approval for the addition of a Time-of-Flight detector was granted in January 1999. The installation of the TOF detector was completed in August 2001 and its data has been included in the CDFII readout since then. The primary physics motivation for TOF is to complement and enhance the particle identification capability provided by the central drift chamber (COT) since it distinguishes K{sup {+-}} and {pi}{sup {+-}} in the momentum region of their cross-over in dE=dX. With an expected time-of-flight resolution of 100 ps, the TOF system will be capable of identifying charged kaons from pions by their flight time difference with at least two standard deviation separation up to kaon momenta of 1.6 GeV/c. Such an addition results in an enhancement of the b flavor identification power, crucial to improve the statistical precision in CP violation and B{sub s} mixing measurements.

  6. Femtosecond melting and ablation of semiconductors studied with time of flight mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Cavalleri, Andrea; Sokolowski-Tinten, Klaus; Bialkowski, Joerg; Schreiner, Michaela; von der Linde, Dietrich

    1999-03-01

    Using time-of-flight mass spectroscopy, we have investigated melting and ablation of gallium arsenide and silicon irradiated by femtosecond pulses. Below the ablation threshold the maximum surface temperature is obtained from the collisionless time-of-flight distributions of evaporated or sublimated particles. At the melting threshold, we estimate a temperature for the silicon surface which is approximately 500 K higher than the equilibrium melting temperature. In the fluence regime where melting is known to be a nonthermal process, we measure maximum surface temperatures in excess of 2500 K for both silicon and gallium arsenide, indicating rapid thermalization after nonthermal melting. At the ablation threshold, we estimated for both materials surface temperatures between 3000 and 4000 K. We observed a clear threshold-like effect in the number of detected particles, indicating the occurrence of a bulk effect. The flow parameters above the ablation threshold are discussed and compared to the different models of collisional expansion. For Fabl2Fabl, we find evidence that expansion takes place at temperatures that are higher than the critical temperature. Plasma formation appears only at fluences above 1 J/cm2 (F>5Fabl).

  7. TOF plotter—a program to perform routine analysis time-of-flight mass spectral data

    NASA Astrophysics Data System (ADS)

    Knippel, Brad C.; Padgett, Clifford W.; Marcus, R. Kenneth

    2004-03-01

    The main article discusses the operation and application of the program to mass spectral data files. This laboratory has recently reported the construction and characterization of a linear time-of-flight mass spectrometer (ToF-MS) utilizing a radio frequency glow discharge ionization source. Data acquisition and analysis was performed using a digital oscilloscope and Microsoft Excel, respectively. Presently, no software package is available that is specifically designed for time-of-flight mass spectral analysis that is not instrument dependent. While spreadsheet applications such as Excel offer tremendous utility, they can be cumbersome when repeatedly performing tasks which are too complex or too user intensive for macros to be viable. To address this situation and make data analysis a faster, simpler task, our laboratory has developed a Microsoft Windows-based software program coded in Microsoft Visual Basic. This program enables the user to rapidly perform routine data analysis tasks such as mass calibration, plotting and smoothing on x- y data sets. In addition to a suite of tools for data analysis, a number of calculators are built into the software to simplify routine calculations pertaining to linear ToF-MS. These include mass resolution, ion kinetic energy and single peak identification calculators. A detailed description of the software and its associated functions is presented followed by a characterization of its performance in the analysis of several representative ToF-MS spectra obtained from different GD-ToF-MS systems.

  8. High-Resolution Magnetic Resonance Angiography in the Mouse Using a Nanoparticle Blood-Pool Contrast Agent

    PubMed Central

    Howles, Gabriel P.; Ghaghada, Ketan B.; Qi, Yi; Mukundan, Srinivasan; Johnson, G. Allan

    2009-01-01

    High-resolution magnetic resonance angiography is already a useful tool for studying mouse models of human disease. Magnetic resonance angiography in the mouse is typically performed using time-of-flight) contrast. In this work, a new long-circulating blood-pool contrast agent—a liposomal nanoparticle with surface-conjugated gadolinium (SC-Gd liposomes)—was evaluated for use in mouse neurovascular magnetic resonance angiography. A total of 12 mice were imaged. Scan parameters were optimized for both time-of-flight and SC-Gd contrast. Compared to time-of-flight contrast, SC-Gd liposomes (0.08 mmol/kg) enabled improved small-vessel contrast-to-noise ratio, larger field of view, shorter scan time, and imaging of venous structures. For a limited field of view, time-of-flight and SC-Gd were not significantly different; however, SC-Gd provided better contrast-to-noise ratio when the field of view encompassed the whole brain (P < 0.001) or the whole neurovascular axis (P < 0.001). SC-Gd allowed acquisition of high-resolution magnetic resonance angiography (52 × 52 × 100 micrometer3 or 0.27 nL), with 123% higher (P < 0.001) contrast-to-noise ratio in comparable scan time (~45 min). Alternatively, SC-Gd liposomes could be used to acquire high-resolution magnetic resonance angiography (0.27 nL) with 32% higher contrast-to-noise ratio (P < 0.001) in 75% shorter scan time (12 min). PMID:19902507

  9. Linking high resolution mass spectrometry data with exposure ...

    EPA Pesticide Factsheets

    There is a growing need in the field of exposure science for monitoring methods that rapidly screen environmental media for suspect contaminants. Measurement and analysis platforms, based on high resolution mass spectrometry (HRMS), now exist to meet this need. Here we describe results of a study that links HRMS data with exposure predictions from the U.S. EPA's ExpoCast™ program and in vitro bioassay data from the U.S. interagency Tox21 consortium. Vacuum dust samples were collected from 56 households across the U.S. as part of the American Healthy Homes Survey (AHHS). Sample extracts were analyzed using liquid chromatography time-of-flight mass spectrometry (LC–TOF/MS) with electrospray ionization. On average, approximately 2000 molecular features were identified per sample (based on accurate mass) in negative ion mode, and 3000 in positive ion mode. Exact mass, isotope distribution, and isotope spacing were used to match molecular features with a unique listing of chemical formulas extracted from EPA's Distributed Structure-Searchable Toxicity (DSSTox) database. A total of 978 DSSTox formulas were consistent with the dust LC–TOF/molecular feature data (match score ≥ 90); these formulas mapped to 3228 possible chemicals in the database. Correct assignment of a unique chemical to a given formula required additional validation steps. Each suspect chemical was prioritized for follow-up confirmation using abundance and detection frequency results, along wi

  10. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

    SciTech Connect

    Zhang, Y. Huang, S. L. Wang, S.; Zhao, W.

    2016-05-15

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  11. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals.

    PubMed

    Zhang, Y; Huang, S L; Wang, S; Zhao, W

    2016-05-01

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  12. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Huang, S. L.; Wang, S.; Zhao, W.

    2016-05-01

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  13. High Resolution TPM Cosmological Simulations

    NASA Astrophysics Data System (ADS)

    Xu, Guohong

    1995-01-01

    studied several variations of Cold Dark Matter (CDM) type. The standard CDM model, although with many known problems, is treated to compare with the previous simulations. The low density models with and without a cosmological constant are of special interest because they give better fit to the large scale structure and much observational evidence implies that Omega_0 < 1.. With our high resolution simulations, we are specially interested to study the structure of the objects from different cosmological models. The slopes of the dark halo density profiles from different models are only slightly different from each other, with a broad distribution within each model. All the models can successfully produce flat rotation curves for dark halos. We find the biggest difference in the cluster structure among various models is the predicted X-ray core radius. The standard CDM model predicts bigger X-ray core radius than the low density models, but all the models predicts smaller core radius than that from X-ray observations. We find the low density models can produce significant substructures in X-ray clusters to be in agreement with observations, while the X-ray clusters in the standard CDM model are known to have abundant substructures.

  14. Development and Validation of a New Blade Element Momentum Skewed-Wake Model within AeroDyn: Preprint

    SciTech Connect

    Ning, S. A.; Hayman, G.; Damiani, R.; Jonkman, J.

    2014-12-01

    Blade element momentum methods, though conceptually simple, are highly useful for analyzing wind turbines aerodynamics and are widely used in many design and analysis applications. A new version of AeroDyn is being developed to take advantage of new robust solution methodologies, conform to a new modularization framework for National Renewable Energy Laboratory's FAST, utilize advanced skewed-wake analysis methods, fix limitations with previous implementations, and to enable modeling of highly flexible and nonstraight blades. This paper reviews blade element momentum theory and several of the options available for analyzing skewed inflow. AeroDyn implementation details are described for the benefit of users and developers. These new options are compared to solutions from the previous version of AeroDyn and to experimental data. Finally, recommendations are given on how one might select from the various available solution approaches.

  15. Increasing throughput and information content for in vitro drug metabolism experiments using ultra-performance liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer.

    PubMed

    Castro-Perez, Jose; Plumb, Robert; Granger, Jennifer H; Beattie, Iain; Joncour, Karine; Wright, Andrew

    2005-01-01

    The field of drug metabolism has been revolutionized by liquid chromatography/mass spectrometry (LC/MS) applications with new technologies such as triple quadrupoles, ion traps and time-of-flight (ToF) instrumentation. Over the years, these developments have often relied on the improvements to the mass spectrometer hardware and software, which has allowed users to benefit from lower levels of detection and ease-of-use. One area in which the development pace has been slower is in high-performance liquid chromatography (HPLC). In the case of metabolite identification, where there are many challenges due to the complex nature of the biological matrices and the diversity of the metabolites produced, there is a need to obtain the most accurate data possible. Reactive or toxic metabolites need to be detected and identified as early as possible in the drug discovery process, in order to reduce the very costly attrition of compounds in late-phase development. High-resolution, exact mass measurement plays a very important role in metabolite identification because it allows the elimination of false positives and the determination of non-trivial metabolites in a much faster throughput environment than any other standard current methodology available to this field. By improving the chromatographic resolution, increased peak capacity can be achieved with a reduction in the number of co-eluting species leading to superior separations. The overall enhancement in the chromatographic resolution and peak capacity is transferred into a net reduction in ion suppression leading to an improvement in the MS sensitivity. To investigate this, a number of in vitro samples were analyzed using an ultra-performance liquid chromatography (UPLC) system, with columns packed with porous 1.7 mum particles, coupled to a hybrid quadrupole time-of-flight (ToF) mass spectrometer. This technique showed very clear examples for fundamental gains in sensitivity, chromatographic resolution and speed of

  16. Quantitative myocardial blood flow imaging with integrated time-of-flight PET-MR.

    PubMed

    Kero, Tanja; Nordström, Jonny; Harms, Hendrik J; Sörensen, Jens; Ahlström, Håkan; Lubberink, Mark

    2017-12-01

    The use of integrated PET-MR offers new opportunities for comprehensive assessment of cardiac morphology and function. However, little is known on the quantitative accuracy of cardiac PET imaging with integrated time-of-flight PET-MR. The aim of the present work was to validate the GE Signa PET-MR scanner for quantitative cardiac PET perfusion imaging. Eleven patients (nine male; mean age 59 years; range 46-74 years) with known or suspected coronary artery disease underwent (15)O-water PET scans at rest and during adenosine-induced hyperaemia on a GE Discovery ST PET-CT and a GE Signa PET-MR scanner. PET-MR images were reconstructed using settings recommended by the manufacturer, including time-of-flight (TOF). Data were analysed semi-automatically using Cardiac VUer software, resulting in both parametric myocardial blood flow (MBF) images and segment-based MBF values. Correlation and agreement between PET-CT-based and PET-MR-based MBF values for all three coronary artery territories were assessed using regression analysis and intra-class correlation coefficients (ICC). In addition to the cardiac PET-MR reconstruction protocol as recommended by the manufacturer, comparisons were made using a PET-CT resolution-matched reconstruction protocol both without and with TOF to assess the effect of time-of-flight and reconstruction parameters on quantitative MBF values. Stress MBF data from one patient was excluded due to movement during the PET-CT scanning. Mean MBF values at rest and stress were (0.92 ± 0.12) and (2.74 ± 1.37) mL/g/min for PET-CT and (0.90 ± 0.23) and (2.65 ± 1.15) mL/g/min for PET-MR (p = 0.33 and p = 0.74). ICC between PET-CT-based and PET-MR-based regional MBF was 0.98. Image quality was improved with PET-MR as compared to PET-CT. ICC between PET-MR-based regional MBF with and without TOF and using different filter and reconstruction settings was 1.00. PET-MR-based MBF values correlated well with PET-CT-based MBF values

  17. Toward Respiratory Assessment Using Depth Measurements from a Time-of-Flight Sensor.

    PubMed

    Sharp, Charles; Soleimani, Vahid; Hannuna, Sion; Camplani, Massimo; Damen, Dima; Viner, Jason; Mirmehdi, Majid; Dodd, James W

    2017-01-01

    Introduction: There is increasing interest in technologies that may enable remote monitoring of respiratory disease. Traditional methods for assessing respiratory function such as spirometry can be expensive and require specialist training to perform and interpret. Remote, non-contact tracking of chest wall movement has been explored in the past using structured light, accelerometers and impedance pneumography, but these have often been costly and clinical utility remains to be defined. We present data from a 3-Dimensional time-of-flight camera (found in gaming consoles) used to estimate chest volume during routine spirometry maneuvres. Methods: Patients were recruited from a general respiratory physiology laboratory. Spirometry was performed according to international standards using an unmodified spirometer. A Microsoft Kinect V2 time-of-flight depth sensor was used to reconstruct 3-dimensional models of the subject's thorax to estimate volume-time and flow-time curves following the introduction of a scaling factor to transform measurements to volume estimates. The Bland-Altman method was used to assess agreement of model estimation with simultaneous recordings from the spirometer. Patient characteristics were used to assess predictors of error using regression analysis and to further explore the scaling factors. Results: The chest volume change estimated by the Kinect camera during spirometry tracked respiratory rate accurately and estimated forced vital capacity (FVC) and vital capacity to within ± <1%. Forced expiratory volume estimation did not demonstrate acceptable limits of agreement, with 61.9% of readings showing >150 ml difference. Linear regression including age, gender, height, weight, and pack years of smoking explained 37.0% of the variance in the scaling factor for volume estimation. This technique had a positive predictive value of 0.833 to detect obstructive spirometry. Conclusion: These data illustrate the potential of 3D time-of-flight cameras

  18. Toward Respiratory Assessment Using Depth Measurements from a Time-of-Flight Sensor

    PubMed Central

    Sharp, Charles; Soleimani, Vahid; Hannuna, Sion; Camplani, Massimo; Damen, Dima; Viner, Jason; Mirmehdi, Majid; Dodd, James W.

    2017-01-01

    Introduction: There is increasing interest in technologies that may enable remote monitoring of respiratory disease. Traditional methods for assessing respiratory function such as spirometry can be expensive and require specialist training to perform and interpret. Remote, non-contact tracking of chest wall movement has been explored in the past using structured light, accelerometers and impedance pneumography, but these have often been costly and clinical utility remains to be defined. We present data from a 3-Dimensional time-of-flight camera (found in gaming consoles) used to estimate chest volume during routine spirometry maneuvres. Methods: Patients were recruited from a general respiratory physiology laboratory. Spirometry was performed according to international standards using an unmodified spirometer. A Microsoft Kinect V2 time-of-flight depth sensor was used to reconstruct 3-dimensional models of the subject's thorax to estimate volume-time and flow-time curves following the introduction of a scaling factor to transform measurements to volume estimates. The Bland-Altman method was used to assess agreement of model estimation with simultaneous recordings from the spirometer. Patient characteristics were used to assess predictors of error using regression analysis and to further explore the scaling factors. Results: The chest volume change estimated by the Kinect camera during spirometry tracked respiratory rate accurately and estimated forced vital capacity (FVC) and vital capacity to within ± <1%. Forced expiratory volume estimation did not demonstrate acceptable limits of agreement, with 61.9% of readings showing >150 ml difference. Linear regression including age, gender, height, weight, and pack years of smoking explained 37.0% of the variance in the scaling factor for volume estimation. This technique had a positive predictive value of 0.833 to detect obstructive spirometry. Conclusion: These data illustrate the potential of 3D time-of-flight cameras

  19. Development of grazing incidence devices for space-borne time of flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Cadu, A.; Devoto, P.; Louarn, P.; Sauvaud, J.-A.

    2012-04-01

    Time of flight mass spectrometer is widely used to study space plasmas in planetary and solar missions. This space-borne instrument selects ions in function of their energy through an electrostatic analyzer. Particles are then post-accelerated to energies in the range of 20 keV to cross a carbon foil. At the foil exit, electrons are emitted and separated from ion beam in the time of flight section. A first detector (a Micro-Channel Plate or MCP) emits a start signal at electron arrival and a second one emits a stop signal at incident ion end of path. The time difference gives the speed of the particle and its mass can be calculated, knowing its initial energy. However, current instruments suffer from strong limitations. The post acceleration needs very high voltage power supplies which are heavy, have a high power consumption and imply technical constraints for the development. A typical instrument weighs from 5 to 6 kg, includes a 20 kV power supply, consumes a least 5 W and encounters corona effect and electrical breakdown problems. Moreover, despite the particle high energy range, scattering and straggling phenomena in the carbon foil significantly reduce the instrument overall resolution. Some methods, such as electrostatic focus lenses or reflectrons, really improve mass separation but global system efficiency remains very low because of the charge state dependence of such devices. The main purpose of our work is to replace carbon foil by grazing incidence MCP's - also known as MPO's, for Micro Pore Optics - for electron emission. Thus, incident particles would back-scatter onto the channel inner surface with an angle of a few degrees. With this solution, we can decrease dispersion sources and lower the power supplies to post accelerate ions. The result would be a lighter and simpler instrument with a substantial resolution improvement. We have first simulated MPO's behavior with TRIM and MARLOWE Monte-Carlo codes. Energy scattering and output angle computed

  20. Fully 3D list-mode time-of-flight PET image reconstruction on GPUs using CUDA.

    PubMed

    Cui, Jing-Yu; Pratx, Guillem; Prevrhal, Sven; Levin, Craig S

    2011-12-01

    List-mode processing is an efficient way of dealing with the sparse nature of positron emission tomography (PET) data sets and is the processing method of choice for time-of-flight (ToF) PET image reconstruction. However, the massive amount of computation involved in forward projection and backprojection limits the application of list-mode reconstruction in practice, and makes it challenging to incorporate accurate system modeling. The authors present a novel formulation for computing line projection operations on graphics processing units (GPUs) using the compute unified device architecture (CUDA) framework, and apply the formulation to list-mode ordered-subsets expectation maximization (OSEM) image reconstruction. Our method overcomes well-known GPU challenges such as divergence of compute threads, limited bandwidth of global memory, and limited size of shared memory, while exploiting GPU capabilities such as fast access to shared memory and efficient linear interpolation of texture memory. Execution time comparison and image quality analysis of the GPU-CUDA method and the central processing unit (CPU) method are performed on several data sets acquired on a preclinical scanner and a clinical ToF scanner. When applied to line projection operations for non-ToF list-mode PET, this new GPU-CUDA method is >200 times faster than a single-threaded reference CPU implementation. For ToF reconstruction, we exploit a ToF-specific optimization to improve the efficiency of our parallel processing method, resulting in GPU reconstruction >300 times faster than the CPU counterpart. For a typical whole-body scan with 75 × 75 × 26 image matrix, 40.7 million LORs, 33 subsets, and 3 iterations, the overall processing time is 7.7 s for GPU and 42 min for a single-threaded CPU. Image quality and accuracy are preserved for multiple imaging configurations and reconstruction parameters, with normalized root mean squared (RMS) deviation less than 1% between CPU and GPU

  1. High resolution scintillation detector with semiconductor readout

    DOEpatents

    Levin, Craig S.; Hoffman, Edward J.

    2000-01-01

    A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

  2. High Resolution PDF Measurements on Ag Nanoparticles

    SciTech Connect

    Rocha, Tulio C. R.; Martin, Chris; Kycia, Stefan; Zanchet, Daniela

    2009-01-29

    The quantitative analysis of structural defects in Ag nanoparticles was addressed in this work. We performed atomic scale structural characterization by a combination of x-ray diffraction (XRD) using the Pair Distribution Function analysis (PDF) and High Resolution Transmission Electron Microscopy (HRTEM). The XRD measurements were performed using an innovative instrumentation setup to provide high resolution PDF patterns.

  3. Characterization of submicron particles influenced by mixed biogenic and anthropogenic emissions using high-resolution aerosol mass spectrometry: results from CARES

    SciTech Connect

    Setyan, Ari; Zhang, Qi; Merkel, M.; Knighton, Walter B.; Sun, Y.; Song, Chen; Shilling, John E.; Onasch, Timothy B.; Herndon, Scott C.; Worsnop, Douglas R.; Fast, Jerome D.; Zaveri, Rahul A.; Berg, Larry K.; Wiedensohler, A.; Flowers, B. A.; Dubey, Manvendra K.; Subramanian, R.

    2012-09-11

    The Carbonaceous Aerosols and Radiative Effects Study (CARES) took place in the Sacramento Valley of California in summer 2010. We present results obtained at Cool, CA, the T1 site of the project ({approx}40 km downwind of urban emissions from Sacramento), where we deployed an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in parallel with complementary instrumentation to characterize the sources and processes of submicron particles (PM1). Cool is located at the foothill of the Sierra Nevada Mountains, where intense biogenic emissions are periodically mixed with urban outflow transported by daytime southwesterly winds from the Sacramento metropolitan area. The particle mass loading was low (3.0 {micro}gm{sup -3} on average) and dominated by organics (80% of the PM1 mass) followed by sulfate (9.9 %). Organics and sulfate appeared to be externally mixed, as suggested by their different time series (r2 = 0.13) and size distributions. Sulfate showed a bimodal distribution with a droplet mode peaking at {approx}400nm in vacuum aerodynamic diameter (Dva), and a condensation mode at {approx}150 nm, while organics generally displayed a broad distribution in 60-600nm (Dva). New particle formation and growth events were observed almost every day, emphasizing the roles of organics and sulfate in new particle growth, especially that of organics. The organic aerosol (OA) had a nominal formula of C{sub 1}H{sub 1.38}N{sub 0.004}O{sub 0.44}, thus an average organic mass-to-carbon (OM/OC) ratio of 1.70. Two different oxygenated OA (OOA, 90% of total OA mass) and a hydrocarbon-like OA (HOA, 10 %) were identified by Positive matrix factorization (PMF) of the high resolution mass spectra. The more oxidized MO-OOA (O/C = 0.54) corresponded to secondary OA (SOA) primarily influenced by biogenic emissions, while the less oxidized LO-OOA (O/C = 0.42) corresponded to SOA associated with urban transport. The HOA factor corresponded to primary emissions mainly

  4. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Stone, M. B.; Niedziela, J. L.; Abernathy, D. L.; DeBeer-Schmitt, L.; Ehlers, G.; Garlea, O.; Granroth, G. E.; Graves-Brook, M.; Kolesnikov, A. I.; Podlesnyak, A.; Winn, B.

    2014-04-01

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments are not exclusive and overlap significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  5. Time-of-flight calibration of a 6Li glass epithermal neutron detector

    PubMed

    Livingston; Saleh; Block; Brand

    2000-10-01

    The curing of Portland cement concrete involves the conversion of water from a free to a bound state. The process can be monitored nondestructively by measuring the shift in the neutron energy spectrum in the epithermal range (0.025-1 eV). A tuned array of 6Li glass detectors has been constructed with varying efficiencies over the epithermal energy range. To determine the efficiency of each detector as a function of neutron energy, it is necessary to calibrate it against a reference neutron spectrum. This was accomplished using a time-of-flight approach with a pulsed neutron beam produced at the Gaerttner LINAC Laboratory at Rensselaer Polytechnic Institute. With a neutron flight path of 25 m it was possible to determine the neutron detector efficiencies to an energy resolution of 11 microeV. The data showed good agreement with the detector design calculations.

  6. Analysis of black powder by ion mobility-time-of-flight mass spectrometry.

    PubMed

    Crawford, Christina L; Boudries, Hacene; Reda, Ralph J; Roscioli, Kristyn M; Kaplan, Kimberly A; Siems, William F; Hill, Herbert H

    2010-01-01

    Ion mobility-time-of-flight mass spectrometry (IM-TOFMS) was used to identify and correlate response ions associated with three black powder samples by mass and mobility. Vapors produced by thermal desorption of the black powders were ionized by a (63)Ni source; subsequent response ions were separated and identified using IM-TOFMS. The same response ions were found for each black powder regardless of geographic origin. The most intense mass and mobility peaks were attributed to ionic forms of sulfur allotropes ((32)S(n)(-), where n = 1-5). Vapor samples from GOEX black powder were also analyzed by two stand-alone ion mobility spectrometry systems, yielding an average reduced mobility value (K(o)) of 2.28 +/- 0.02 cm(2) V(-1) s(-1) for black powder across all three instruments.

  7. Time-of-flight mobility and trapping results for ZnSe.

    NASA Technical Reports Server (NTRS)

    Heaton, J. L., III; Hammond, G. H.; Goldner, R. B.

    1972-01-01

    Results of measurements of time-of-flight mobility and trapping for zinc selenide. The data were obtained at room temperature for electric fields in the range from 30,000 to 800,000 V/cm. A relatively constant hole mobility (about 50 sq cm/V sec) was found for the entire range of investigated fields. The electron mobility was approximately constant (about 400 sq cm/V sec) up to approximately equal to 300,000 V/cm, above which the drift velocity remained constant. No obvious negative differential mobility was observed, even though the Gunn effect has been reported for the field range investigated. Trapping and detrapping times in the vicinity of 1 nsec are reported for both holes and electrons. The field dependence of the electron-trapping times is unusual and remains unexplained.

  8. Pose estimation and tracking of non-cooperative rocket bodies using Time-of-Flight cameras

    NASA Astrophysics Data System (ADS)

    Gómez Martínez, Harvey; Giorgi, Gabriele; Eissfeller, Bernd

    2017-10-01

    This paper presents a methodology for estimating the position and orientation of a rocket body in orbit - the target - undergoing a roto-translational motion, with respect to a chaser spacecraft, whose task is to match the target dynamics for a safe rendezvous. During the rendezvous maneuver the chaser employs a Time-of-Flight camera that acquires a point cloud of 3D coordinates mapping the sensed target surface. Once the system identifies the target, it initializes the chaser-to-target relative position and orientation. After initialization, a tracking procedure enables the system to sense the evolution of the target's pose between frames. The proposed algorithm is evaluated using simulated point clouds, generated with a CAD model of the Cosmos-3M upper stage and the PMD CamCube 3.0 camera specifications.

  9. Recovering three-dimensional shape around a corner using ultrafast time-of-flight imaging.

    PubMed

    Velten, Andreas; Willwacher, Thomas; Gupta, Otkrist; Veeraraghavan, Ashok; Bawendi, Moungi G; Raskar, Ramesh

    2012-03-20

    The recovery of objects obscured by scattering is an important goal in imaging and has been approached by exploiting, for example, coherence properties, ballistic photons or penetrating wavelengths. Common methods use scattered light transmitted through an occluding material, although these fail if the occluder is opaque. Light is scattered not only by transmission through objects, but also by multiple reflection from diffuse surfaces in a scene. This reflected light contains information about the scene that becomes mixed by the diffuse reflections before reaching the image sensor. This mixing is difficult to decode using traditional cameras. Here we report the combination of a time-of-flight technique and computational reconstruction algorithms to untangle image information mixed by diffuse reflection. We demonstrate a three-dimensional range camera able to look around a corner using diffusely reflected light that achieves sub-millimetre depth precision and centimetre lateral precision over 40 cm×40 cm×40 cm of hidden space.

  10. Standardization of time-of-flight laser ionization mass spectrometry analysis of minerals

    NASA Astrophysics Data System (ADS)

    Dimov, S. S.; Chryssoulis, S. L.

    1998-03-01

    The standardization of the time-of-flight laser ionization mass spectrometry (TOF-LIMS) analysis of mineral surfaces is an important step towards providing reproducible quantitative data. This paper reports the search for experimental conditions and instrumental configurations that provide efficient ionization for all elements of the sample. For that purpose, an investigation of the neutral emission dynamics and the ion yields for the most important elements, as a function of laser power densities, the relative time delay between the ablation and postionization processes, and the sample matrix, was performed. In order to standardize the procedure, an empirical protocol was established, based on the use of optimized system parameters to monitor the ion yield from a library of standard reference samples.

  11. Measurement of residual strain in composites by means of time-of- flight neutron diffraction

    SciTech Connect

    Kupperman, D.S.; Majumdar, S.; Richardson, J.; Saigal, A.

    1993-05-01

    Neutron diffraction time-of-flight measurements using the Intense Pulsed Neutron Source at Argonne National Laboratory have been employed to study strain in various metal- and ceramic-matrix composites. For example, measurements carried out to 900 C on a composite composed of a titanium alloy matrix and silicon carbide fibers have been used to validate theoretical assumptions in the prediction of fabrication-induced residual stress. Sapphire reinforced nickel aluminide composites have also been studied. Studies of a high-temperature ceramic superconducting composite consisting of yttrium barium copper oxide and silver with various volume fractions of silver have also been carried out. The results of these studies have provided information on the effect of Ag content on interface bonding. In addition, ceramic-matrix composites with randomly dispersed ceramic whiskers with varying fiber content have been investigated.

  12. Measurement of residual strain in composites by means of time-of- flight neutron diffraction

    SciTech Connect

    Kupperman, D.S.; Majumdar, S.; Richardson, J. . Materials and Components Technology Div.); Saigal, A. . Dept. of Mechanical Engineering)

    1993-01-01

    Neutron diffraction time-of-flight measurements using the Intense Pulsed Neutron Source at Argonne National Laboratory have been employed to study strain in various metal- and ceramic-matrix composites. For example, measurements carried out to 900 C on a composite composed of a titanium alloy matrix and silicon carbide fibers have been used to validate theoretical assumptions in the prediction of fabrication-induced residual stress. Sapphire reinforced nickel aluminide composites have also been studied. Studies of a high-temperature ceramic superconducting composite consisting of yttrium barium copper oxide and silver with various volume fractions of silver have also been carried out. The results of these studies have provided information on the effect of Ag content on interface bonding. In addition, ceramic-matrix composites with randomly dispersed ceramic whiskers with varying fiber content have been investigated.

  13. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source

    SciTech Connect

    Stone, Matthew B; Niedziela, Jennifer L; Abernathy, Douglas L; Debeer-Schmitt, Lisa M; Garlea, Vasile O; Granroth, Garrett E; Graves-Brook, Melissa K; Ehlers, Georg; Kolesnikov, Alexander I; Podlesnyak, Andrey A; Winn, Barry L

    2014-04-01

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments is not exclusive and overlaps significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  14. Detection of chlorobenzene derivatives using vacuum ultraviolet ionization time-of-flight mass spectrometry.

    PubMed

    Tonokura, Kenichi; Nakamura, Tomohisa; Koshi, Mitsuo

    2003-08-01

    Vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS) has been applied for the detection of chlorobenzene, o-dichlorobenzene, and o-chlorophenol as surrogates for polychlorinated dibenzo-p-dioxine/furans (PCDD/F). The photoionization mass spectra of these compounds appear to be fragmentation free in the ionization processes by the VUV-SPI at 10.2 eV (121.6 nm). Quantum chemical calculations support no fragmentation in the photoionization of chlorobenzene derivatives at around 10 eV. The absolute photoionization cross-sections of chlorobenzene, o-dichlorobenzene, and o-chlorophenol were estimated at 10.2 eV. The photoionization cross-section is an important parameter in the detection of chlorobenzene derivatives by the single-photon ionization technique. The detection limit for chlorobenzene is on the order of tenth parts-per-billion volume (ppbv) in the present experimental setup.

  15. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source.

    PubMed

    Stone, M B; Niedziela, J L; Abernathy, D L; DeBeer-Schmitt, L; Ehlers, G; Garlea, O; Granroth, G E; Graves-Brook, M; Kolesnikov, A I; Podlesnyak, A; Winn, B

    2014-04-01

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments are not exclusive and overlap significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  16. Underwater 3D scanning using Kinect v2 time of flight camera

    NASA Astrophysics Data System (ADS)

    Anwer, Atif; Ali, Syed Saad Azhar; Khan, Amjad; Mériaudeau, Fabrice

    2017-03-01

    This paper presents preliminary results of using commercial time of flight depth camera for 3D scanning of underwater objects. Generating accurate and detailed 3D models of objects in underwater environment is a challenging task. This work presents experimental results of using Microsoft Kinect v2 depth camera for dense depth data acquisition underwater that gives reasonable 3D scanned data but with smaller scanning range. Motivations for this research are the user friendliness and low-cost of the device as compared to multi view stereo cameras or marine-hardened laser scanning solutions and equipment. Preliminary results of underwater point cloud generation and volumetric reconstruction are also presented. The novelty of this work is the utilization of the Kinect depth camera for real-time 3D mesh reconstruction and the main objective is to develop an economical and compact solution for underwater 3D scanning.

  17. A new neutron time-of-flight detector for fuel-areal-density measurements on OMEGA

    SciTech Connect

    Glebov, V. Yu. Forrest, C. J.; Marshall, K. L.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C.

    2014-11-15

    A new neutron time-of-flight (nTOF) detector for fuel-areal-density measurements in cryogenic DT implosions was installed on the OMEGA Laser System. The nTOF detector has a cylindrical thin-wall, stainless-steel, 8-in.-diam, 4-in.-thick cavity filled with an oxygenated liquid xylene scintillator. Four gated photomultiplier tubes (PMTs) with different gains are used to measure primary DT and D{sub 2} neutrons, down-scattered neutrons in nT and nD kinematic edge regions, and to study tertiary neutrons in the same detector. The nTOF detector is located 13.4 m from target chamber center in a well-collimated line of sight. The design details of the nTOF detector, PMT optimization, and test results on OMEGA will be presented.

  18. A Design for a Compact Time-of-Flight Mass Spectrometer

    SciTech Connect

    Manard, M.

    2012-10-01

    The design of a prototype, compact time-of-flight (TOF) mass spectrometer (MS) is described. The system primarily consists of an ion acceleration/focusing/steering assembly (AFSA), an 8 cm field-free region, a 4 cm, dual-stage reflectron and a miniature microchannel plate detector. Consequently, the resulting flight length of the system is 12 cm. The system has been designed with the capability to sample directly from atmosphere at ambient pressures. This is accomplished through the use of an electrodynamic ion funnel, housed in an intermediate-vacuum chamber that is coupled to the inlet of the TOF chamber. TOF spectra were obtained using noble gases (Ar, Kr and Xe) as test chemicals. These measured flight times were used to probe the performance of the instrument. A temporal resolution (tflight/Δt) of approximately 125, acquired using 129Xe+, has been measured for the system.

  19. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source

    SciTech Connect

    Stone, M. B.; Abernathy, D. L.; Ehlers, G.; Garlea, O.; Podlesnyak, A.; Winn, B.; Niedziela, J. L.; DeBeer-Schmitt, L.; Graves-Brook, M.; Granroth, G. E.; Kolesnikov, A. I.

    2014-04-15

    The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments are not exclusive and overlap significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.

  20. Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

    NASA Astrophysics Data System (ADS)

    Du, Rong; Tian, Haolai; Zuo, Taisen; Tang, Ming; Yan, Lili; Zhang, Junrong

    2017-09-01

    Small-angle neutron scattering (SANS) is an experimental technique to detect material structures in the nanometer to micrometer range. The solution of the structural model constructed from SANS strongly depends on the accuracy of the reduced data. The time-of-flight (TOF) SANS data are dependent on the wavelength of the pulsed neutron source. Therefore, data reduction must be handled very carefully to transform measured neutron events into neutron scattering intensity. In this study, reduction algorithms for TOF SANS data are developed and optimized using simulated data from a virtual neutron experiment. Each possible effect on the measured data is studied systematically, and suitable corrections are performed to obtain high-quality data. This work will facilitate scientific research and the instrument design at China Spallation Neutron Source.

  1. Studies of polyisobutylene using time-of-flight secondary ion mass spectrometry (TOF-SIMS)

    NASA Astrophysics Data System (ADS)

    Xu, Keyang; Proctor, Andrew; Hercules, David M.

    1995-05-01

    A series of polyisobutylenes (PIBs) with average molecular weights from 800 to 4 × 105 were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The PIB spectra consist of a sequence of repeating patterns. Four clusters are observed within each pattern. Each cluster corresponds to several species, which are neutral fragments generated from polymer chain scission, cationized by a silver ion. The species formed have various numbers of double bonds and/or rings, and are separated by two mass units. The data indicate that the average molecular weight of PIB affects the ion formation. It changes the relative cluster intensities in a pattern, and also varies the cluster structures. More fragment-ion species can be detected from a high molecular weight polymer, and the unsaturated fragments are predominant. In addition to the large fragments, small fragment ions also provide information about some structurally important features.

  2. Campaign 1.7 Pu Aging. Development of Time of Flight Secondary Ion Mass Spectroscopy

    SciTech Connect

    Venhaus, Thomas J.

    2015-09-09

    The first application of Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) to an aged plutonium surface has resulted in a rich set of surface chemistry data, as well as some unexpected results. FY15 was highlighted by not only the first mapping of hydrogen-containing features within the metal, but also a prove-in series of experiments using the system’s Sieverts Reaction Cell. These experiments involved successfully heating the sample to ~450 oC for nearly 24 hours while the sample was dosed several times with hydrogen, followed by an in situ ToF-SIMS analysis. During this year, the data allowed for better and more consistent identification of the myriad peaks that result from the SIMS sputter process. In collaboration with the AWE (U.K), the system was also fully aligned for sputter depth profiling for future experiments.

  3. Particle identification with the ALICE Time-Of-Flight detector at the LHC

    NASA Astrophysics Data System (ADS)

    Alici, A.

    2014-12-01

    High performance Particle Identification system (PID) is a distinguishing characteristic of the ALICE experiment at the CERN Large Hadron Collider (LHC). Charged particles in the intermediate momentum range are identified in ALICE by the Time-Of-Flight (TOF) detector. The TOF exploits the Multi-gap Resistive Plate Chamber (MRPC) technology, capable of an intrinsic time resolution at the level of few tens of ps with an overall efficiency close to 100% and a large operation plateau. The full system is made of 1593 MRPC chambers with a total area of 141 m2, covering the pseudorapidity interval [-0.9,+0.9] and the full azimuthal angle. The ALICE TOF system has shown very stable operation during the first 3 years of collisions at the LHC. In this paper a summary of the system performance as well as main results with data from collisions will be reported.

  4. The MRPC-based ALICE time-of-flight detector: Status andperformance

    NASA Astrophysics Data System (ADS)

    Alici, A.; ALICE Collaboration

    2013-04-01

    The large time-of-flight (TOF) array is one of the main detectors devoted to charged hadron identification in the mid-rapidity region of the ALICE experiment at the LHC. It allows separation among pions, kaons and protons up to a few GeV/c, covering the full azimuthal angle and -0.9<η<0.9. The TOF exploits the innovative MRPC technology capable of an intrinsic time resolution better than 50 ps with an efficiency close to 100% and a large operational plateau; the full array consists of 1593 MRPCs covering a cylindrical surface of 141 m2. The TOF detector has been efficiently taking data since the first pp collisions recorded in ALICE in December 2009. In this report, the status of the TOF detector and the performance achieved for both pp and Pb-Pb collisions aredescribed.

  5. Status and performance of the ALICE MRPC-based Time-Of-Flight detector

    NASA Astrophysics Data System (ADS)

    Alici, A.

    2012-10-01

    ALICE is the dedicated heavy-ion experiment at the CERN LHC. One of the main detectors devoted to charged hadron identification in the ALICE central barrel is a large Time-Of-Flight (TOF) array; it allows separation among pions, kaons and protons up to a few GeV/c, covering the full azimuthal angle and -0.9 < η < 0.9. The very good performance required for such a system has been achieved by means of the Multigap Resistive Plate Chamber (MRPC) whose intrinsic time resolution is better than 50 ps with an overall efficiency close to 100% and a large operational plateau; the full array consists of 1593 MRPCs covering a cylindrical surface of 141 m2. In this report, the status of the TOF detector and the performance achieved during the 2010 and 2011 data taking periods are reported together with selected physics results obtained with pp and Pb-Pb collisions.

  6. Analyzing neutron time-of-flight spectra from the National Ignition Facility using moments

    NASA Astrophysics Data System (ADS)

    Hatarik, R.; Field, J.; Eckart, M.; Grim, G.; Hartouni, E. P.; Moore, A.; Munro, D.; Sayre, D.

    2016-10-01

    The neutron spectrum produced by an indirectly driven implosion at the National Ignition Facility (NIF) provides valuable insight into the performance of the capsule. There are four neutron time-of-flight (nTOF) spectrometers being used at the NIF which can simultaneously measure DD and DT fusion neutrons on NIF shots. The width of theses peaks have been traditionally associated with the temperature of the plasma, recent work shows that it has to be considered a combination of flow and temperature distributions. This leads to a deviation from a pure gaussian shape of a single temperature static plasma and the presence of higher order moments in the neutron spectrum. The current status of the analysis of neutron spectra from the nTOF diagnostics at the NIF will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  7. Analysis of Gait Using a Treadmill and a Time-of-Flight Camera

    NASA Astrophysics Data System (ADS)

    Jensen, Rasmus R.; Paulsen, Rasmus R.; Larsen, Rasmus

    We present a system that analyzes human gait using a treadmill and a Time-of-flight camera. The camera provides spatial data with local intensity measures of the scene, and data are collected over several gait cycles. These data are then used to model and analyze the gait. For each frame the spatial data and the intensity image are used to fit an articulated model to the data using a Markov random field. To solve occlusion issues the model movement is smoothened providing the missing data for the occluded parts. The created model is then cut into cycles, which are matched and through Fourier fitting a cyclic model is created. The output data are: Speed, Cadence, Step length and Range-of-motion. The described output parameters are computed with no user interaction using a setup with no requirements to neither background nor subject clothing.

  8. An Improvement on Space Focusing Resolution in Two-Field Time-of-Flight Mass Spectrometers

    SciTech Connect

    Yildirim, M.; Aydin, R.; Akin, U.; Kilic, H. S.; Sise, O.; Ulu, M.; Dogan, M.

    2007-04-23

    Time-of-Flight Mass Spectrometer (TOFMS) is a sophisticated device for the mass selective analysis of a variety of samples. The main limitation on TOFMS technique is the obtainable resolution where the two main limiting factors are the initial space and energy spread of particles created in ionization region. Similar charged particles starting at different points will reach the detector at different times. So, this problem makes space focusing is very important subject. We have presented principles of two-fields TOFMS with second-order space focusing both using analytical methods and ray-tracing simulation. This work aims understanding of ion optical system clearly and gives hint of expectation for future developments.

  9. High precision laser ranging by time-of-flight measurement of femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Lee, Joohyung; Lee, Keunwoo; Lee, Sanghyun; Kim, Seung-Woo; Kim, Young-Jin

    2012-06-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits the production of a balanced optical cross-correlation signal between two overlapping light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances of 1.5, 60 and 700 m. This method is found well suited for future space missions based on formation-flying satellites as well as large-scale industrial applications for land surveying, aircraft manufacturing and shipbuilding.

  10. Laser ranging by time-of-flight measurement of femtosecond light pulses

    NASA Astrophysics Data System (ADS)

    Kim, Young-Jin

    2014-04-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits producing the balanced optical cross-correlation signal between two overlapped light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances from 1.5 m to 700 m. This method is found suited for terrestrial land surveying and space missions of formation-flying satellites.

  11. Integrated multi-channel receiver for a pulsed time-of-flight laser radar

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Liu, Ruqing; Zhu, Jingguo

    2015-04-01

    An integrated multi-channel receiver for a pulsed time-of-flight (TOF) laser rangefinder has been designed in this paper. The receiver chip as an important component of the laser radar device has been implemented in a 0.18um CMOS process. It consists of sixteen channels and every channel includes preamplifier, amplifier stages, high-pass filter and a timing discriminator which contains a timing comparator and a noise comparator. Each signal paths is independent of other channels. Based on the simulations, the bandwidth and transimpedance of the amplifier channel are 652MHz, 99dBΩ. Under the simulation condition of TT corner and 27°C, the propagation delay of the discriminator is 2.15ns and the propagation delay dispersion is 223ps. The power consumption during continuous measurement is 810mW, and the operating temperature range of the device is -10~60°C.

  12. Depth Imaging by Combining Time-of-Flight and On-Demand Stereo

    NASA Astrophysics Data System (ADS)

    Hahne, Uwe; Alexa, Marc

    In this paper we present a framework for computing depth images at interactive rates. Our approach is based on combining time-of-flight (TOF) range data with stereo vision. We use a per-frame confidence map extracted from the TOF sensor data in two ways for improving the disparity estimation in the stereo part: first, together with the TOF range data for initializing and constraining the disparity range; and, second, together with the color image information for segmenting the data into depth continuous areas, enabling the use of adaptive windows for the disparity search. The resulting depth images are more accurate than from either of the sensors. In an example application we use the depth map to initialize the z-buffer so that virtual objects can be occluded by real objects in an augmented reality scenario.

  13. Time-of-flight electron spectrometer for a broad range of kinetic energies

    SciTech Connect

    Kothe, Alexander; Metje, Jan; Wilke, Martin; Moguilevski, Alexandre; Engel, Nicholas; Al-Obaidi, Ruba; Richter, Clemens; Golnak, Ronny; Kiyan, Igor Yu.; Aziz, Emad F.

    2013-02-15

    A newly constructed time-of-flight electron spectrometer of the magnetic bottle type is characterized for electron detection in a broad range of kinetic energies. The instrument is designed to measure the energy spectra of electrons generated from liquids excited by strong laser fields and photons in the range of extreme ultra violet and soft X-rays. Argon inner shell electrons were recorded to calibrate the spectrometer and investigate its characteristics, such as energy resolution and collection efficiency. Its energy resolution {Delta}E/E of 1.6% allows resolving the Ar 2p spin orbit structure at kinetic energies higher than 100 eV. The collection efficiency is determined and compared to that of the spectrometer in its field-free configuration.

  14. Time-of-flight electron spectrometer for a broad range of kinetic energies.

    PubMed

    Kothe, Alexander; Metje, Jan; Wilke, Martin; Moguilevski, Alexandre; Engel, Nicholas; Al-Obaidi, Ruba; Richter, Clemens; Golnak, Ronny; Kiyan, Igor Yu; Aziz, Emad F

    2013-02-01

    A newly constructed time-of-flight electron spectrometer of the magnetic bottle type is characterized for electron detection in a broad range of kinetic energies. The instrument is designed to measure the energy spectra of electrons generated from liquids excited by strong laser fields and photons in the range of extreme ultra violet and soft X-rays. Argon inner shell electrons were recorded to calibrate the spectrometer and investigate its characteristics, such as energy resolution and collection efficiency. Its energy resolution ΔE/E of 1.6% allows resolving the Ar 2p spin orbit structure at kinetic energies higher than 100 eV. The collection efficiency is determined and compared to that of the spectrometer in its field-free configuration.

  15. Porosity detection in ceramic armor tiles via ultrasonic time-of-flight

    SciTech Connect

    Margetan, Frank J.; Richter, Nathaniel; Jensen, Terrence

    2011-06-23

    Some multilayer armor panels contain ceramic tiles as one constituent, and porosity in the tiles can affect armor performance. It is well known that porosity in ceramic materials leads to a decrease in ultrasonic velocity. We report on a feasibility study exploring the use of ultrasonic time-of-flight (TOF) to locate and characterize porous regions in armor tiles. The tiles in question typically have well-controlled thickness, thus simplifying the translation of TOF data into velocity data. By combining UT velocity measurements and X-ray absorption measurements on selected specimens, one can construct a calibration curve relating velocity to porosity. That relationship can then be used to translate typical ultrasonic C-scans of TOF-versus-position into C-scans of porosity-versus-position. This procedure is demonstrated for pulse/echo, focused-transducer inspections of silicon carbide (SiC) ceramic tiles.

  16. Time of flight elastic recoil detection analysis with a position sensitive detector

    SciTech Connect

    Siketic, Zdravko; Radovic, Iva Bogdanovic; Jaksic, Milko; Skukan, Natko

    2010-03-15

    A position sensitive detection system based on the microchannel plate detector has been constructed and installed at the existing time of flight (TOF) spectrometer in order to perform a kinematic correction and improve the surface time/depth resolution of elastic recoil detection analysis (ERDA) system. The position resolution of the detector has been tested for different types of ions and anode voltages. TOF spectra of recoiled O ions from SiO{sub 2} and F from CaF{sub 2} were collected in coincidence with position sensitive detector signal. Kinematic correction of TOF spectra improved surface time/depth resolution by {approx}20% for our system; however even higher improvements could be obtained in larger solid angle TOF-ERDA systems.

  17. Separation of rare earth isotopes using resonance ionization time-of-flight mass spectrometry

    SciTech Connect

    Armstrong, D.P.; McCulla, W.H.; Schweitzer, G.K.

    1985-01-01

    Stable isotopes comprise a very large portion of the periodic table. They find a wide variety of applications, which include serving as precursors for radioisotopes and radiopharmaceuticals and as accelerated particle targets. Isotopes of the lanthanides, with very high boiling points and low natural abundances, are often difficult to separate by conventional electromagnetic techniques. Photoionization is a potential alternative method. We have devised a system in which an atomic beam of the rare earth metal is admitted to the ionization region of a time-of-flight mass spectrometer. Photoionization is achieved using a pulsed, two-photon laser scheme. Preliminary results from the photoionization of samarium are discussed. 5 refs., 3 figs., 1 tab.

  18. Stopping power measurements with the Time-of-Flight (ToF) technique

    SciTech Connect

    Fontana, Cristiano L.; Chen, Chien-Hung; Crespillo, Miguel L.; Graham, Joseph T.; Xue, Haizhou; Zhang, Yanwen; Weber, William J.

    2015-11-10

    In our review of measurements of the stopping power of ions in matter is presented along with new measurements of the stopping powers of O, Si, Ti, and Au ions in self-supporting thin foils of SiO2, Nb2O5, and Ta2O5. Moreover, a Time-of-Flight system at the Ion Beam Materials Laboratory at the University of Tennessee, Knoxville, was used in transmission geometry in order to reduce experimental uncertainties. Finally, the resulting stopping powers show good precision and accuracy and corroborate previously quoted values in the literature. New stopping data are determined.

  19. Encrypted Three-dimensional Dynamic Imaging using Snapshot Time-of-flight Compressed Ultrafast Photography

    NASA Astrophysics Data System (ADS)

    Liang, Jinyang; Gao, Liang; Hai, Pengfei; Li, Chiye; Wang, Lihong V.

    2015-10-01

    Compressed ultrafast photography (CUP), a computational imaging technique, is synchronized with short-pulsed laser illumination to enable dynamic three-dimensional (3D) imaging. By leveraging the time-of-flight (ToF) information of pulsed light backscattered by the object, ToF-CUP can reconstruct a volumetric image from a single camera snapshot. In addition, the approach unites the encryption of depth data with the compressed acquisition of 3D data in a single snapshot measurement, thereby allowing efficient and secure data storage and transmission. We demonstrated high-speed 3D videography of moving objects at up to 75 volumes per second. The ToF-CUP camera was applied to track the 3D position of a live comet goldfish. We have also imaged a moving object obscured by a scattering medium.

  20. Recovering three-dimensional shape around a corner using ultrafast time-of-flight imaging

    NASA Astrophysics Data System (ADS)

    Velten, Andreas; Willwacher, Thomas; Gupta, Otkrist; Veeraraghavan, Ashok; Bawendi, Moungi G.; Raskar, Ramesh

    2012-03-01

    The recovery of objects obscured by scattering is an important goal in imaging and has been approached by exploiting, for example, coherence properties, ballistic photons or penetrating wavelengths. Common methods use scattered light transmitted through an occluding material, although these fail if the occluder is opaque. Light is scattered not only by transmission through objects, but also by multiple reflection from diffuse surfaces in a scene. This reflected light contains information about the scene that becomes mixed by the diffuse reflections before reaching the image sensor. This mixing is difficult to decode using traditional cameras. Here we report the combination of a time-of-flight technique and computational reconstruction algorithms to untangle image information mixed by diffuse reflection. We demonstrate a three-dimensional range camera able to look around a corner using diffusely reflected light that achieves sub-millimetre depth precision and centimetre lateral precision over 40 cm×40 cm×40 cm of hidden space.

  1. Time of flight spectrometer for background-free positron annihilation induced Auger electron spectroscopy

    SciTech Connect

    Mukherjee, S.; Shastry, K.; Anto, C. V.; Joglekar, P. V.; Nadesalingam, M. P.; Xie, S.; Jiang, N.; Weiss, A. H.

    2016-03-15

    We describe a novel spectrometer designed for positron annihilation induced Auger electron spectroscopy employing a time-of-flight spectrometer. The spectrometer’s new configuration enables us to implant monoenergetic positrons with kinetic energies as low as 1.5 eV on the sample while simultaneously allowing for the detection of electrons emitted from the sample surface at kinetic energies ranging from ∼500 eV to 0 eV. The spectrometer’s unique characteristics made it possible to perform (a) first experiments demonstrating the direct transition of a positron from an unbound scattering state to a bound surface state and (b) the first experiments demonstrating that Auger electron spectra can be obtained down to 0 eV without the beam induced secondary electron background obscuring the low energy part of the spectra. Data are presented which show alternative means of estimating positron surface state binding energy and background-free Auger spectra.

  2. Time of flight spectrometer for background-free positron annihilation induced Auger electron spectroscopy.

    PubMed

    Mukherjee, S; Shastry, K; Anto, C V; Joglekar, P V; Nadesalingam, M P; Xie, S; Jiang, N; Weiss, A H

    2016-03-01

    We describe a novel spectrometer designed for positron annihilation induced Auger electron spectroscopy employing a time-of-flight spectrometer. The spectrometer's new configuration enables us to implant monoenergetic positrons with kinetic energies as low as 1.5 eV on the sample while simultaneously allowing for the detection of electrons emitted from the sample surface at kinetic energies ranging from ∼500 eV to 0 eV. The spectrometer's unique characteristics made it possible to perform (a) first experiments demonstrating the direct transition of a positron from an unbound scattering state to a bound surface state and (b) the first experiments demonstrating that Auger electron spectra can be obtained down to 0 eV without the beam induced secondary electron background obscuring the low energy part of the spectra. Data are presented which show alternative means of estimating positron surface state binding energy and background-free Auger spectra.

  3. Invited Article: Polarization ``Down Under'': The polarized time-of-flight neutron reflectometer PLATYPUS

    NASA Astrophysics Data System (ADS)

    Saerbeck, T.; Klose, F.; Le Brun, A. P.; Füzi, J.; Brule, A.; Nelson, A.; Holt, S. A.; James, M.

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

  4. High precision electric gate for time-of-flight ion mass spectrometers

    NASA Technical Reports Server (NTRS)

    Sittler, Edward C. (Inventor)

    2011-01-01

    A time-of-flight mass spectrometer having a chamber with electrodes to generate an electric field in the chamber and electric gating for allowing ions with a predetermined mass and velocity into the electric field. The design uses a row of very thin parallel aligned wires that are pulsed in sequence so the ion can pass through the gap of two parallel plates, which are biased to prevent passage of the ion. This design by itself can provide a high mass resolution capability and a very precise start pulse for an ion mass spectrometer. Furthermore, the ion will only pass through the chamber if it is within a wire diameter of the first wire when it is pulsed and has the right speed so it is near all other wires when they are pulsed.

  5. Encrypted Three-dimensional Dynamic Imaging using Snapshot Time-of-flight Compressed Ultrafast Photography.

    PubMed

    Liang, Jinyang; Gao, Liang; Hai, Pengfei; Li, Chiye; Wang, Lihong V

    2015-10-27

    Compressed ultrafast photography (CUP), a computational imaging technique, is synchronized with short-pulsed laser illumination to enable dynamic three-dimensional (3D) imaging. By leveraging the time-of-flight (ToF) information of pulsed light backscattered by the object, ToF-CUP can reconstruct a volumetric image from a single camera snapshot. In addition, the approach unites the encryption of depth data with the compressed acquisition of 3D data in a single snapshot measurement, thereby allowing efficient and secure data storage and transmission. We demonstrated high-speed 3D videography of moving objects at up to 75 volumes per second. The ToF-CUP camera was applied to track the 3D position of a live comet goldfish. We have also imaged a moving object obscured by a scattering medium.

  6. Objective Error Criterion for Evaluation of Mapping Accuracy Based on Sensor Time-of-Flight Measurements.

    PubMed

    Barshan, Billur

    2008-12-15

    An objective error criterion is proposed for evaluating the accuracy of maps of unknown environments acquired by making range measurements with different sensing modalities and processing them with different techniques. The criterion can also be used for the assessment of goodness of fit of curves or shapes fitted to map points. A demonstrative example from ultrasonic mapping is given based on experimentally acquired time-of-flight measurements and compared with a very accurate laser map, considered as absolute reference. The results of the proposed criterion are compared with the Hausdorff metric and the median error criterion results. The error criterion is sufficiently general and flexible that it can be applied to discrete point maps acquired with other mapping techniques and sensing modalities as well.

  7. TOFwave: reproducibility in biomarker discovery from time-of-flight mass spectrometry data.

    PubMed

    Chierici, Marco; Albanese, Davide; Franceschi, Pietro; Furlanello, Cesare

    2012-11-01

    Many are the sources of variability that can affect reproducibility of disease biomarkers from time-of-flight (TOF) Mass Spectrometry (MS) data. Here we present TOFwave, a complete software pipeline for TOF-MS biomarker identification, that limits the impact of parameter tuning along the whole chain of preprocessing and model selection modules. Peak profiles are obtained by a preprocessing based on Continuous Wavelet Transform (CWT), coupled with a machine learning protocol aimed at avoiding selection bias effects. Only two parameters (minimum peak width and a signal to noise cutoff) have to be explicitly set. The TOFwave pipeline is built on top of the mlpy Python package. Examples on Matrix-Assisted Laser Desorption and Ionization (MALDI) TOF datasets are presented. Software prototype, datasets and details to replicate results in this paper can be found at http://mlpy.sf.net/tofwave/.

  8. Star Time of Flight Readout Electronics, Daq, and Cosmic Ray Test Stand

    NASA Astrophysics Data System (ADS)

    Schambach, J.; Hoffmann, G.; Kajimoto, K.; Bridges, L.; Eppley, G.; Liu, J.; Llope, B.; Nussbaum, T.; Mesa, C.

    The new Time-of-Flight (TOF) subsystem for STAR at RHIC will have 3840 6-pad Multigap Resistive Plate Chambers (MRPC) distributed over 120 trays. Each tray contains 192 channels and three types of electronics cards: “TINO”, “TDIG” and “TCPU”. Every 30 trays send data to a “THUB” card that interfaces to STAR trigger and transmits data over fiber to a STAR DAQ fiber receiver. TINO contains analog front end electronics based on the CERN/LAA NINO custom IC. TDIG digitizes the data using the CERN HPTDC ASIC. TCPU formats and buffers the digital information. A cosmic ray test system comprised of three plastic scintillators, 4 MRPC modules, and TOF prototype electronics is used to determine the timing resolution to be achieved for the entire TOF system. Overall timing resolution of 80 - 110 ps has been achieved.

  9. Laser Time-of-Flight Mass Spectrometry for Future In Situ Planetary Missions

    NASA Technical Reports Server (NTRS)

    Getty, S. A.; Brinckerhoff, W. B.; Cornish, T.; Ecelberger, S. A.; Li, X.; Floyd, M. A. Merrill; Chanover, N.; Uckert, K.; Voelz, D.; Xiao, X.; Tawalbeh, R.; Glenar, D.; Elsila, J. E.; Callahan, M.

    2012-01-01

    Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) is a versatile, low-complexity instrument class that holds significant promise for future landed in situ planetary missions that emphasize compositional analysis of surface materials. Here we describe a 5kg-class instrument that is capable of detecting and analyzing a variety of analytes directly from rock or ice samples. Through laboratory studies of a suite of representative samples, we show that detection and analysis of key mineral composition, small organics, and particularly, higher molecular weight organics are well suited to this instrument design. A mass range exceeding 100,000 Da has recently been demonstrated. We describe recent efforts in instrument prototype development and future directions that will enhance our analytical capabilities targeting organic mixtures on primitive and icy bodies. We present results on a series of standards, simulated mixtures, and meteoritic samples.

  10. Development of picoseconds Time of Flight systems in Meson Test Beam Facility at Fermilab

    SciTech Connect

    Ronzhin, A.; Albrow, M.; Demarteau, M.; Los, S.; Malik, S.; Pronko, S.; Ramberg, E.; Zatserklyaniy, A.; /Puerto Rico U., Mayaguez

    2010-11-01

    The goal of the work is to develop time of flight (TOF) system with about 10 picosecond time resolution in real beam line when start and stop counters separated by some distance. We name the distance as 'base' for the TOF. This 'real' TOF setup is different from another one when start and stop counters located next to each other. The real TOF is sensitive to beam momentum spread, beam divergence, etc. Anyway some preliminary measurements are useful with close placement of start and stop counter. We name it 'close geometry'. The work started about 2 years ago at Fermilab Meson Test Beam Facility (MTBF). The devices tested in 'close geometry' were Microchannel Plate Photomultipliers (MCP PMT) with Cherenkov radiators. TOF counters based on Silicon Photomultipliers (SiPms) with Cherenkov radiators also in 'close geometry' were tested. We report here new results obtained with the counters in the MTBF at Fermilab, including beam line data.

  11. Development of a correction method for the time-of-flight prompt gamma-ray analysis

    NASA Astrophysics Data System (ADS)

    Huang, M.; Toh, Y.; Ebihara, M.; Kimura, A.; Nakamura, S.

    2017-03-01

    A new analytical technique, time-of-flight prompt gamma-ray analysis, has been developed at the Japan Proton Accelerator Research Complex. In order to apply it to accurate elemental analysis, a set of Fe and Au reference samples were measured to examine the several factors which affect the number of detected events. It was found that major contributing factors included attenuations of neutrons and gamma rays in the sample, live-time fraction and signal pile-up correction. A simulation model was built for the estimation of neutron and gamma-ray attenuations. A simple empirical formula was proposed to calculate the signal pile-up correction factor. The whole correction method has proven to be accurate and reliable.

  12. Data acquisition system with pulse height capability for the TOFED time-of-flight neutron spectrometer

    SciTech Connect

    Chen, Z. J.; Peng, X. Y.; Zhang, X.; Du, T. F.; Hu, Z. M.; Cui, Z. Q.; Ge, L. J.; Xie, X. F.; Yuan, X.; Li, X. Q.; Zhang, G. H.; Chen, J. X.; Fan, T. S.; Gorini, G.; Nocente, M.; Tardocchi, M.; Hu, L. Q.; Zhong, G. Q.; Lin, S. Y.; Wan, B. N.

    2014-11-15

    A new time-of-flight neutron spectrometer TOFED has been constructed for installation at Experimental Advanced Superconducting Tokamak. A data acquisition system combining measurements of flight time and energy from the interaction of neutrons with the TOFED scintillators has been developed. The data acquisition system can provide a digitizing resolution better than 1.5% (to be compared with the >10% resolution of the recoil particle energy in the plastic scintillators) and a time resolution <1 ns. At the same time, it is compatible with high count rate event recording, which is an essential feature to investigate phenomena occurring on time scales faster than the slowing down time (≈100 ms) of the beam ions in the plasma. Implications of these results on the TOFED capability to resolve fast ion signatures in the neutron spectrum from EAST plasmas are discussed.

  13. Data acquisition system with pulse height capability for the TOFED time-of-flight neutron spectrometer.

    PubMed

    Chen, Z J; Peng, X Y; Zhang, X; Du, T F; Hu, Z M; Cui, Z Q; Ge, L J; Xie, X F; Yuan, X; Gorini, G; Nocente, M; Tardocchi, M; Hu, L Q; Zhong, G Q; Lin, S Y; Wan, B N; Li, X Q; Zhang, G H; Chen, J X; Fan, T S

    2014-11-01

    A new time-of-flight neutron spectrometer TOFED has been constructed for installation at Experimental Advanced Superconducting Tokamak. A data acquisition system combining measurements of flight time and energy from the interaction of neutrons with the TOFED scintillators has been developed. The data acquisition system can provide a digitizing resolution better than 1.5% (to be compared with the >10% resolution of the recoil particle energy in the plastic scintillators) and a time resolution <1 ns. At the same time, it is compatible with high count rate event recording, which is an essential feature to investigate phenomena occurring on time scales faster than the slowing down time (≈100 ms) of the beam ions in the plasma. Implications of these results on the TOFED capability to resolve fast ion signatures in the neutron spectrum from EAST plasmas are discussed.

  14. Denoising and Multivariate Analysis of Time-Of-Flight SIMS Images

    SciTech Connect

    Wickes, Bronwyn; Kim, Y.; Castner, David G.

    2003-08-30

    Time-of-flight SIMS (ToF-SIMS) imaging offers a modality for simultaneously visualizing the spatial distribution of different surface species. However, the utility of ToF-SIMS datasets may be limited by their large size, degraded mass resolution and low ion counts per pixel. Through denoising and multivariate image analysis, regions of similar chemistries may be differentiated more readily in ToF-SIMS image data. Three established denoising algorithms down-binning, boxcar and wavelet filtering were applied to ToF-SIMS images of different surface geometries and chemistries. The effect of these filters on the performance of principal component analysis (PCA) was evaluated in terms of the capture of important chemical image features in the principal component score images, the quality of the principal component

  15. Optimization of a multi-ring detector for Ps time of flight measurements

    NASA Astrophysics Data System (ADS)

    Di Noto, L.; Benetti, M.; Mariazzi, S.; Dalla Betta, G.-F.; Brusa, R. S.

    2013-06-01

    We have designed a multi-ring detector (MRD) based on Bismuth Germanate (BGO) crystals, coupled to Silicon PhotoMultipliers (SiPM) for measuring the Ps time of flight (TOF). The set-up geometry was optimized by Monte Carlo simulations to take into account at different Ps velocities: (i) the background noise due to backscattered positrons, (ii) the crosstalk between adjacent detectors, (iii) the lifetime of Ps decay. Three parameters were defined to evaluate the different configurations and a figure of merit was obtained. This allows the choice of the best set up configuration for measuring Ps emitted with a particular energy range, optimizing the signal to noise ratio and keeping the acquisition time acceptable.

  16. A new neutron time-of-flight detector for fuel-areal-density measurements on OMEGA.

    PubMed

    Glebov, V Yu; Forrest, C J; Marshall, K L; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C

    2014-11-01

    A new neutron time-of-flight (nTOF) detector for fuel-areal-density measurements in cryogenic DT implosions was installed on the OMEGA Laser System. The nTOF detector has a cylindrical thin-wall, stainless-steel, 8-in.-diam, 4-in.-thick cavity filled with an oxygenated liquid xylene scintillator. Four gated photomultiplier tubes (PMTs) with different gains are used to measure primary DT and D2 neutrons, down-scattered neutrons in nT and nD kinematic edge regions, and to study tertiary neutrons in the same detector. The nTOF detector is located 13.4 m from target chamber center in a well-collimated line of sight. The design details of the nTOF detector, PMT optimization, and test results on OMEGA will be presented.

  17. Joint Temperature-Lasing Mode Compensation for Time-of-Flight LiDAR Sensors

    PubMed Central

    Alhashimi, Anas; Varagnolo, Damiano; Gustafsson, Thomas

    2015-01-01

    We propose an expectation maximization (EM) strategy for improving the precision of time of flight (ToF) light detection and ranging (LiDAR) scanners. The novel algorithm statistically accounts not only for the bias induced by temperature changes in the laser diode, but also for the multi-modality of the measurement noises that is induced by mode-hopping effects. Instrumental to the proposed EM algorithm, we also describe a general thermal dynamics model that can be learned either from just input-output data or from a combination of simple temperature experiments and information from the laser’s datasheet. We test the strategy on a SICK LMS 200 device and improve its average absolute error by a factor of three. PMID:26690445

  18. Quantitative analysis of biomolecules by time-of-flight secondary-ion mass spectrometry: Fundamental considerations

    SciTech Connect

    Muddiman, D.C.; Nicola, A.J.; Proctor, A.

    1995-12-31

    Static Time-of-Flight Secondary-Ion Mass Spectrometry (TOF-SIMS) has been applied to investigate an extensive assortment of analytical systems; from semiconductors to DNA sequencing. Recently, the TOF-SIMS method has been successfully applied to real biological systems. This report focuses on some important aspects that must be taken into consideration when conducting measurements on biomaterials in order to observe the potential the TOF-SIMS method affords. The current data are presented using Cyclosporin A (CsA, 1202 Da) and cocaine (303 Da) as model compounds. CsA is observed in the TOF-SIMS mass spectrum predominately as a Ag-cationized species and cocaine as a protonated species; thus, they are complementary probe molecules.

  19. Laser time-of-flight measurement based on time-delay estimation and fitting correction

    NASA Astrophysics Data System (ADS)

    Li, Chao; Chen, Qian; Gu, Guohua; Qian, Weixian

    2013-07-01

    We describe a method based on multichannel time-delay estimation with linear fitting correction for laser time-of-flight (TOF) measurement. The laser TOF measurement system is constructed with a laser source, a stop receiver channel, a reference receiver multichannel, an analog to digital converter (ADC) sampling unit, and a digital signal processing unit. Limited by the sampling rate, the precision of laser TOF measurement is restricted no more than the ADC sampling period in conventional methods. As this problem is considered, multichannel correlation time-delay estimation with linear fitting correction is devised. It is shown that the measuring precision is better than 2 ns with multichannel time-delay estimation and not influenced by signal-to-noise ratio. The experimental results demonstrate that the proposed method is effective and stable.

  20. Laser time-of-flight measurement based on multi-channel time delay estimation

    NASA Astrophysics Data System (ADS)

    Li, Chao; Chen, Qian; Gu, Guohua; Man, Tian

    2013-03-01

    In this paper, a novel method based on multichannel time delay estimation with linear fitting correction for laser time-of-flight (TOF) measurement is described. The laser TOF measurement system is constructed with a laser source, a stop receiver channel, a reference receiver multichannel, an ADC sampling unit and a digital signal processing unit. Limited by the sampling rate, the precision of laser TOF measurement is restricted no more than the ADC sampling period in conventional methods. As this problem is considered, multi-channel correlation time delay estimation with linear fitting correction is devised. It is shown that the measuring precision is better than 2ns with multi-channel time delay estimation and not influenced by SNR. The experimental results demonstrate that the proposed method is effective and stable.