Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Spectrometer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Compact hyperspectral spectrometers based on semiconductor nanomembranes

Hyperspectral resonant cavity imaging spectrometers and imaging systems incorporating the resonant cavity spectrometers are provided. The spectrometers include an array of photodetectors based on photosensitive semiconductor nanomembranes disposed between two dielectric spacers, each of the dielectric spacers having a thickness gradient along a lateral direction, such that the resonant cavity height differs for different photodetectors in the array.

Ma, Zhenqiang↗
DOE OSTI2019

The SeaQuest spectrometer at Fermilab

The SeaQuest spectrometer at Fermilab was designed to detect oppositely-charged pairs of muons (dimuons) produced by interactions between a 120 GeV proton beam and liquid hydrogen, liquid deuterium and solid nuclear targets. The primary physics program uses the Drell–Yan process to probe antiquark distributions in the target nucleon. The spectrometer consists of a target system, two dipole magnets and four detector stations. The upstream magnet is a closed-aperture solid iron magnet which also serves as the beam dump, while the second magnet is an open aperture magnet. Each of the detector stations consists of scintillator hodoscopes and a high-resolution tracking device. The FPGA-based trigger compares the hodoscope signals to a set of pre-programmed roads to determine if the event contains oppositely-signed, high-mass muon pairs.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Incident beamline design for a modern cold triple axis spectrometer at the High Flux Isotope Reactor

A modern cold triple axis spectrometer is being planned for the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Here, we describe the design of an incident beamline that will put a flux of ~ 10 8 $\frac {n}{cm^{2}s}$ on a sample with an area of 2 cm X 2 cm. It takes current physical constraints at HFIR into account and it can accommodate both single and multiplexed analyzer-detector secondary spectrometers and large superconducting magnets. The proposed incident beamline includes a multi-channel guide with horizontal focusing, a neutron velocity selector, components to facilitate an incident beam polarization option, and a double-focusing pyrolytic graphite monochromator. Here, this work describes the process of optimizing the guide system and monochromator and summarizes the expected performance of the incident beamline for non-polarized operation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Streaked x-ray spectrometer having a discrete selection of Bragg geometries for Omega

The streaked x-ray spectrometer (SXS) is used with streak cameras [D. H. Kalantar, P. M. Bell, R. L. Costa, B. A. Hammel, O. L. Landen, T. J. Orzechowski, J. D. Hares, and A. K. L. Dymoke-Bradshaw, in 22nd International Congress on High-Speed Photography and Photonics, edited by D. L. Paisley and A. M. Frank (SPIE, Bellingham, WA, 1997), Vol. 2869, p. 680] positioned with a ten-inch manipulator on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] and OMEGA EP [L. J. Waxer et al., Presented at CLEO/QELS 2008, San Jose, CA, 4-9 May 2008 (Paper JThB1)] for time-resolved, x-ray spectroscopy of laser-produced plasmas in the 1.4- to 20-keV photon-energy range. These experiments require measuring a portion of this photon-energy range to monitor a particular emission or absorption feature of interest. The SXS relies on a pinned mechanical reference system to create a discrete set of Bragg reflection geometries for a variety of crystals. A wide selection of spectral windows is achieved accurately and efficiently using this technique. It replaces the previous spectrometer designs that had a continuous Bragg angle adjustment and required a tedious alignment calibration procedure. The number of spectral windows needed for the SXS was determined by studying the spectral ranges selected by OMEGA users over the last decade. These selections are easily configured in the SXS using one of the 25 discrete Bragg reflection geometries and one of the six types of Bragg crystals, including two curved crystals.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

A combined electron-ion spectrometer for studying complete kinematics of molecular dissociation upon shell selective ionization

A combined electron-ion spectrometer has been built to study dissociation kinematics of molecular ions upon various electronic decay processes ensuing from ionization of neutral molecules. The apparatus can be used with various ionization agents. Ion time-of-flight (ToF) spectra arising from various electronic decay processes are acquired by triggering the ToF measurement in coincidence with energy analyzed electrons. The design and the performance of the spectrometer in a photoionization experiment is presented in detail. Electron spectra and ion time of flight spectra resulting from valence and 2p{sub 1/2} ionization of Argon and those from valence ionization of CO are presented to demonstrate the capability of the instrument. The fragment ion spectra show remarkable differences (both kinematic and cross sectional) dependent on the energy of the ejected electron, corresponding to various electron loss and decay mechanisms in dissociative photoionization of molecules.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Forward fitting of experimental data from a NE213 neutron detector installed with the magnetic proton recoil upgraded spectrometer at JET

In this paper, we present the results obtained from the data analysis of neutron spectra measured with a NE213 liquid scintillator at JET. We calculated the neutron response matrix of the instrument combining MCNPX simulations, a generic proton light output function measured with another detector and the fit of data from ohmic pulses. For the analysis, we selected a set of pulses with neutral beam injection heating (NBI) only and we applied a forward fitting procedure of modeled spectral components to extract the fraction of thermal neutron emission. The results showed the same trend of the ones obtained with the dedicated spectrometer TOFOR, even though the values from the NE213 analysis were systematically higher. This discrepancy is probably due to the different lines of sight of the two spectrometers (tangential for the NE213, vertical for TOFOR). The uncertainties on the thermal fraction estimates were from 4 to 7 times higher than the ones from the TOFOR analysis.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

GOAmazon Thermal Desorption Chemical Ionization Mass Spectrometer

Ion abundance measured by Thermal Desorption Chemical Ionization Mass Spectrometer (using quadrupole mass spectrometer) Data file format: Column 1: date and time (UTC) Column 2: measurement uncertainty (units: integrated ion counts) Column 3: ion intensity (units: integrated ion counts) Column 4: 1 min SO2 mixing ratio in ppb Measurement uncertainty is +/- 0.2 ppb.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Atomic data for the ITER Core Imaging X-ray Spectrometer

The parameters of the ITER core plasmas will be measured using the Core Imaging X-ray Spectrometer (CIXS), a high-resolution crystal spectrometer focusing on the L-shell spectra of highly ionized tungsten atoms. In order to correctly infer the plasma properties accurate atomic data are required. Here, some aspects of the underlying physics are discussed using experimental data and theoretical predictions from modeling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Tracking Elevated Pollution Layers with a Newly Developed Hyperspectral Sun/Sky Spectrometer (4STAR): Results from the TCAP 2012 and 2013 Campaigns

Total columnar amounts of water vapor, nitrogen dioxide (NO2) and ozone (O3) are derived from a newly developed, hyperspectral airborne sun-sky spectrometer (4STAR) for the first time during the two intensive phases of the Two Column Aerosol Project (TCAP) in summer 2012 and winter 2013 aboard the DOE G-1 aircraft. We compare results with coincident measurements. We find 0.045 g/cm2 (4.2%) negative bias and 0.28 g/cm2 (26.3%) root-mean-square (RMS) difference in water vapor layer comparison with in-situ hygrometer, and an overall RMS difference of 1.28 g/m3 (38%) water vapor amount in profile by profile comparisons, with differences distributed evenly around zero in most cases. The RMS differences for O3 values average to 3%, with a 1% negative bias for 4STAR compared with the spaceborne Ozone Measuring Instrument (OMI) along the aircraft flight-track for 14 flights during both TCAP phases. Ground-based comparisons with the Pandora spectrometer system at the Goddard Space Flight Center (GSFC), Greenbelt, Maryland showed excellent agreement between the instruments for both O3 and NO2, further emphasizing 4STAR’s new capabilities. During the summer phase, we have succeeded in identifying variations in elevated pollution layers corresponding to urban pollution outflow and transported biomass burning. This was done using clustering analysis of the retrieved products (e.g. Ångstrom exponent, NO2 and columnar water vapor), and was confirmed by aerosol type identification by HSRL2 aboard the NASA B-200 aircraft. These newly demonstrated 4STAR capabilities are expected to be instrumental in improving our understanding of atmospheric composition variability and aerosol-trace-gas interactions; they open new horizons and opportunities in airborne sunphotometry.

4STAR↗
DOE OSTI2015

Airborne Single Particle Mass Spectrometers (SPLAT II & miniSPLAT) and New Software for Data Visualization and Analysis in a Geo-Spatial Context

Understanding the effect of aerosols on climate requires knowledge of the size and chemical composition of individual aerosol particles - two fundamental properties that determine an aerosol’s optical properties and ability to serve as cloud condensation or ice nuclei. Here we present miniSPLAT, our new aircraft compatible single particle mass spectrometer, that measures in-situ and in real-time size and chemical composition of individual aerosol particles with extremely high sensitivity, temporal resolution, and sizing precision on the order of a monolayer. miniSPLAT operates in dual data acquisition mode to measure, in addition to single particle size and composition, particle number concentrations, size distributions, density, and asphericity with high temporal resolution. When compared to our previous instrument, SPLAT II, miniSPLAT has been significantly reduced in size, weight, and power consumption without loss in performance. We also present ND-Scope, our newly developed interactive visual analytics software package. ND-Scope is designed to explore and visualize the vast amount of complex, multidimensional data acquired by our single particle mass spectrometers, along with other aerosol and cloud characterization instruments on-board aircraft. We demonstrate that ND-Scope makes it possible to visualize the relationships between different observables and to view the data in a geo-spatial context, using the interactive and fully coupled Google Earth and Parallel Coordinates displays. Here we illustrate the utility of ND-Scope to visualize the spatial distribution of atmospheric particles of different compositions, and explore the relationship between individual particle composition and their activity as cloud condensation nuclei.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

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

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. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Mobility Peak Tailing Reduction in a Differential Mobility Analyzer (DMA) Coupled with a Mass Spectrometer and Several Ionization Sources

The differential mobility analyzer (DMA) is a narrow-band linear ion mobility filter operating at atmospheric pressure. It combines in series with a quadrupole mass spectrometer (Q-MS) for mobility/mass analysis, greatly reducing chemical noise in selected ion monitoring. However, the large flow rate of drift gas (~1000 L/min) required by DMAs complicates the achievement of high gas purity. Additionally, the symmetry of the drying counterflow gas at the interface of many commercial MS instruments, is degraded by the lateral motion of the drift gas at the DMA entrance slit. As a result, DMA mobility peaks often exhibit tails due to the attachment of impurity vapors, either (1) to the reagent ion within the separation cell, or (2) to the analyte of interest in the ionization region. In order to greatly increase the noise-suppression capacity of the DMA, we describe various vapor-removal schemes and measure the resulting increase in the tailing ratio, (TR = signal at the peak maximum over signal two half-widths away from this maximum). Here we develop a low-outgassing DMA circuit connected to a mass spectrometer, and test it with three ionization sources (APCI, Desolvating-nano ESI, and Desolvating low flow SESI). While prior TR values were in the range 100–1000, the three new sources achieve TR ~ 10{sup 5}. The SESI source has been optimized for maximum sensitivity, delivering an unprecedented gain for TNT of 190 counts/fg, equivalent to an ionization efficiency of one out of 140 neutral molecules. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Direct Analysis of Organic Compounds in Liquid Using a Miniature Photoionization Ion Trap Mass Spectrometer with Pulsed Carrier-Gas Capillary Inlet

A miniature ion trap mass spectrometer with capillary direct sampling and vacuum ultraviolet photoionization source was developed to conduct trace analysis of organic compounds in liquids. Self-aspiration sampling is available where the samples are drawn into the vacuum chamber through a capillary with an extremely low flow rate (less than 1 μL/min), which minimizes sample consumption in each analysis to tens of micrograms. A pulsed gas-assisted inlet was designed and optimized to promote sample transmission in the tube and facilitate the cooling of ions, thereby improving instrument sensitivity. A limit of detection of 2 ppb could be achieved for 2,4-dimethylaniline in a methanol solution. The sampling system described in the present study is specifically suitable for a miniature photoionization ion trap mass spectrometer that can perform rapid and online analysis for liquid samples. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

On the Nature of Mass Spectrometer Analyzer Contamination

Sample throughput in electrospray ionization mass spectrometry (ESI-MS) is limited by the need for frequent ion path cleaning to remove accumulated debris that can lead to charging and general performance degradation. Contamination of ion optics within the vacuum system is particularly problematic as routine cleaning requires additional time for cycling the vacuum pumps. Differential mobility spectrometry (DMS) can select targeted ion species for transmission, thereby reducing the total number of charged particles entering the vacuum system. In this work, we characterize the nature of instrument contamination, describe efforts to improve mass spectrometer robustness by applying DMS prefiltering to reduce contamination of the vacuum ion optics, and demonstrate the capability of DMS to extend the interval between mass spectrometer cleaning. In addition, we introduce a new approach to effectively detect large charged particles formed during the electrospray ionization (ESI) process. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

MONSTER: a TOF Spectrometer for β-delayed Neutron Spectroscopy

β-delayed neutron (DN) data, including emission probabilities, Pn, and energy spectrum, play an important role in our understanding of nuclear structure, nuclear astrophysics and nuclear technologies. A MOdular Neutron time-of-flight SpectromeTER (MONSTER) is being built for the measurement of the neutron energy spectra and branching ratios. The TOF spectrometer will consist of one hundred liquid scintillator cells covering a significant solid angle. The MONSTER design has been optimized by using Monte Carlo (MC) techniques. The response function of the MONSTER cell has been characterized with mono-energetic neutron beams and compared to dedicated MC simulations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

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

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.

2E-2v↗
DOE OSTI2019

Refining instrument response functions with 3-D Monte Carlo simulations of differential hard x-ray spectrometers

Three x-ray spectrometers – the hard x-ray detector (HXRD), the bremsstrahlung MeV x-ray spectrometer (BMXS), and the hard x-ray image plate (HXIP) – areused here to estimate hot-electron bremsstrahlung spectrum parameters for inertial confinement fusion experiments on OMEGA. Using 1-D deterministically calculated response functions, they show significantly different estimates of spectrum slope temperature. For all three detectors, 3-D Geant4 Monte Carlo simulations are developed and used to compute instrument response functions. Simulations explain features in raw image-plate data, but only significantly improve systematic errors in predicted detector channel signals for BMXS and do not entirely eliminate the discrepancy between estimates of slope temperature.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗