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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.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Design and Characterization of the Engineering Model of the Spectrometer Onboard LuSEE-Night

The Lunar Surface Electromagnetics Explorer - Night, LuSEE-Night, is a low-frequency radio astronomy experiment that will explore the cosmic Dark Ages signal on the radio quiet farside of the Moon. The LuSEE-Night carries a radio frequency spectrometer consisting of a set of antennas, analog and digital processing electronics, and will be launched by NASA's Commercial Lunar Payload Services in 2025. The spectrometer is designed to observe the spectrum of the radio sky in the 0.5−50MHz band. The engineering model (EM) of the four-channel spectrometer has been developed. The EM has been characterized for linearity, gain, noise, and their temperature dependence, confirming that the EM meets all the requirements for LuSEE-Night. Three mitigation techniques have been implemented and verified to suppress self-induced electromagnetic interference (EMI). The flight model of the spectrometer is currently being developed and is scheduled to be shipped to the integration site in early 2024

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Shortwave Spectrometer (SWS) zenith radiance swsrad.b1 v3 and higher

Hyperspectral zenith radiances from the SWS instrument reported at 1 Hz. This data stream contains calibrated, dark-subtracted, radiances from two grating array spectrometers: a Si-detector based spectrometer denoted by SW and an InGaAs based detector denoted by LW. Spectra from both spectrometers are calibrated based on the spectral responsivity determined by reference against NIST-traceable light sources are reported independently as separate arrays having the same time record but wavelength dimension specified for each detector. Because the LW spectrometer is more susceptible to temperature-induced changes, a scale factor adjustment is applied the the LW spectra to yield agreement with the SW spectra over the wavelength range where they overlap. The final radiances incorporate QC to flag saturated values, periods where house-keeping fields fall outside acceptable bounds, and to flag pixels for which the spectral responsivity is not acceptable.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Determining a location and size of a gas source with a spectrometer gas monitor

A process for determining a location and size of a gas source within an area with a spectrometer gas monitor includes: providing the spectrometer gas monitor; performing fence line monitoring of the area with the spectrometer gas monitor; collecting spectroscopic data over multiple open paths around the area with the spectrometer gas monitor; measuring atmospheric conditions along gas inflows and gas outflows of the area; subtracting a background for a selected gas from the spectroscopic data; applying a boundary constraint to the spectroscopic data; determining an atmospheric concentration of air entering the area; applying bootstrapping to the spectroscopic data; applying zero minimum elimination to the spectroscopic data; and producing inversion data from the spectroscopic data to determine the location and size of the gas source within the area.

03 NATURAL GAS↗
DOE OSTI2010

Correlation spectrometer

A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

47 OTHER INSTRUMENTATION↗
DOE OSTI2010

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

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.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Superresolution of a compact neutron spectrometer at energies relevant for fusion diagnostics

The ability to achieve resolution that is better than the instrument resolution (i.e., superresolution) is well known in optics, where it has been extensively studied. Unfortunately, there are only a handful of theoretical studies concerning superresolution of particle spectrometers, even though experimentalists are familiar with the enhancement of resolution that is achievable when appropriate methods of data analysis are used, such as maximum entropy and Bayesian methods. Knowledge of the superresolution factor is in many cases important. For example, in applications of neutron spectrometry to fusion diagnostics, the temperature of a burning plasma is an important physical parameter which may be inferred from the width of the peak of the neutron energy spectrum, and the ability to determine this width depends on the superresolution factor. Kosarev has derived an absolute limit for resolution enhancement using arguments based on a well known theorem of Shannon. Most calculations of superresolution factors in the literature, however, are based on the assumption of Gaussian, translationally invariant response functions and therefore not directly applicable to neutron spectrometers which typically have response functions not satisfying these requirements. In this work, we develop a procedure that allows us to overcome these difficulties and we derive estimates of superresolution for liquid scintillator spectrometers of a type commonly used for neutron measurements. Theoretical superresolution factors are compared to experimental results.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Nuclear astrophysics studies by SAMURAI spectrometer in RIKEN RIBF

SAMURAI is a spectrometer which is now being constructed at RIKEN RI Beam Factory. This spectrometer is characterized by a large angular-and momentum-acceptance enabling, for example, multi-particle coincidence measurements. Here brief descriptions of SAMURAI spectrometer and physics topics relevant to nuclear astrophysics are presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Prismatic analyser concept for neutron spectrometers

Developments in modern neutron spectroscopy have led to typical sample sizes decreasing from few cm to several mm in diameter samples. We demonstrate how small samples together with the right choice of analyser and detector components makes distance collimation an important concept in crystal analyser spectrometers. We further show that this opens new possibilities where neutrons with different energies are reflected by the same analyser but counted in different detectors, thus improving both energy resolution and total count rate compared to conventional spectrometers. The technique can readily be combined with advanced focussing geometries and with multiplexing instrument designs. We present a combination of simulations and data showing three different energies simultaneously reflected from one analyser. Experiments were performed on a cold triple axis instrument and on a prototype inverse geometry Time-of-flight spectrometer installed at PSI, Switzerland, and shows excellent agreement with the predictions. Typical improvements will be 2.0 times finer resolution and a factor of 1.9 in flux gain compared to a focussing Rowland geometry, or of 3.3 times finer resolution and a factor of 2.4 in flux gain compared to a single flat analyser slab.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2010

Measuring Curved Crystal Performance for a High Resolution, Imaging X-ray Spectrometer

This paper describes the design, crystal selection, and crystal testing for a vertical Johann spectrometer operating in the 13 keV range to measure ion Doppler broadening in inertial confinement plasmas. The spectrometer is designed to use thin, curved, mica crystals to achieve a resolving power of E/ΔE>2000. A number of natural mica crystals were screened for flatness and X-ray diffraction width to find samples of sufficient perfection for use in the instrument. Procedures to select and mount high quality mica samples are discussed. A diode-type X-ray source coupled to a dual goniometer arrangement was used to measure the crystal reflectivity curve. A procedure was developed for evaluating the goniometer performance using a set of diffraction grade Si crystals. This goniometer system was invaluable for identifying the best original crystals for further use and developing the techniques to select satisfactory curved crystals for the spectrometer.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Design of a Moderated Multidetector Neutron Spectrometer for Optimal Specificity

Neutron spectrometry can play an important role in the detection and identification of neutron-emitting sources in various security applications. In the present work, a portable filtered array neutron spectrometer, consisting of twelve 6LiF-based thermal neutron detectors embedded within a single heterogeneous volume was designed and its expected performance compared to that of a commercially available 12-sphere Bonner spheres spectrometer. Each detector within the volume was designed to optimally respond to a unique portion of the neutron spectrum by varying the type and thickness of materials used to filter the spectrum as well as the thickness of the moderator in front of the detector. The available design space was permuted and performance metrics developed to identify the optimal geometries. The top performing detector geometries were then combinatorially explored to identify the best array of geometries that yielded the most information about a neutron spectrum. The best performing filtered array was found to provide as much spectral information as, or more than, the commercially available 12-sphere Bonner spheres spectrometer to which it was compared.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Full-Array Noise Performance of Deployment-Grade SuperSpec mm-Wave On-Chip Spectrometers

SuperSpec is an on-chip filter bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results, we have demonstrated noise performance in individual detectors suitable for photon noise-limited ground-based observations at excellent mm-wave sites. Here, we present the noise performance of a full R similar to 275 spectrometer measured using deployment-ready RF hardware and software. We report typical noise equivalent powers through the full device of similar to 3x10 -16 W Hz -1/2 at expected sky loadings, which are photon noise dominated. Based on these results, we plan to deploy a six-spectrometer demonstration instrument to the Large Millimeter Telescope in early 2020.

47 OTHER INSTRUMENTATION↗
DOE OSTI2010

Differential Mobility Spectrometry/Mass Spectrometry: The Design of a New Mass Spectrometer for Real-Time Chemical Analysis in the Field

The design of a prototype, field-portable mass spectrometer (MS) is described. The MS has been designed with an atmospheric interface in order to couple the system to a commercially available differential mobility spectrometer. The differential mobility spectrometer provides selective injection of trace-level analytes of interest into the inlet of the MS for real-time chemical detection. To accomplish this task, the MS design incorporates the use of an electrodynamic ion funnel to transport the ion beam, generated at atmospheric pressure, to the high-vacuum chamber that houses the mass analyzer. This leads to a design that utilizes two stages of differential pumping to achieve an overall pressure drop from atmosphere (760 Torr) to approximately 1 ×

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2017

Development of a solenoid spectrometer for nuclear astrophysical studies of fusion reactions near stellar energies

Here, a solenoid spectrometer for nuclear astrophysics (SSNAP) has been developed to study heavy-ion fusion reactions of astrophysical importance near stellar energies. Charged particles follow helical trajectories within the strong magnetic field of a superconducting solenoid. The 12 C( 12 C,p) 23 Na reaction was studied as the first measurement using the solenoid spectrometer at the University of Notre Dame within the energy range of E c.m. = 4.0 to 6.0 MeV. This experiment demonstrated that the solenoid spectrometer is able to provide outstanding capability for detection of light charged particles produced by nuclear fusion reactions having a relatively wide energy range.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Implementation and assessment of resolution-dependent elastic incoherent neutron scattering measurements at a backscattering spectrometer for probing relaxations in complex systems

We introduce the use of a higher-order reflection, Si(333), of the silicon analyzer crystals at a backscattering spectrometer to implement analysis of the relaxation dynamics in the samples. Here, this is achieved by monitoring the temperature dependence of the neutron scattering intensity perceived as elastic when measured using Si(111), Si(311), and Si(333) reflections. As a test case, we use a sample with well-characterized, but complex, relaxation pattern, where the non-Lorentzian relaxation function is known to exhibit a set of parameters specific to each temperature point and scattering momentum transfer (Q) value. Even for this very general relaxation pattern, characterized by no constrains on the relaxation function parameters, we successfully map the relaxation times measured using the present approach onto those previously obtained from the full analysis of the quasielastic neutron scattering signal. Analysis of the Q-specific activation energies becomes possible for the Q values accessible simultaneously through Si(111), Si(311), and Si(333) reflections (in the present case, 0.9 Å –1 < Q < 1.9 Å –1 ). While the dedicated neutron spectrometers for this type of analysis are yet to be constructed, we show that the present-day backscattering spectrometers can be employed, under certain conditions, to analyze temperature dependence of the relaxation time in the samples not amenable to traditional full analysis of the quasielastic neutron scattering signal.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Design of the High Rigidity Spectrometer at FRIB

A High Rigidity Spectrometer (HRS) has been designed for experiments at the Facility for Rare-Isotope Beams (FRIB) at Michigan State University (MSU). The HRS will allow experiments to be performed with the most exotic neutron-rich isotopes at high beam energies (≳100 MeV/u). The HRS consists of an analysis beamline called the High-Transmission Beamline (HTBL) and the spectrometer proper called the Spectrometer Section. Here, the maximum magnetic rigidity of the HRS is 8 Tm, which corresponds to the rigidities at which rare-isotope beams are optimally produced at FRIB. The resolving power, angular acceptance, and momentum acceptance are set to match the anticipated scientific program. An ion-optical design developed for the HRS is described in detail, along with the specifications of the associated magnet and detector systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

The SHMS 11 GeV/c spectrometer in Hall C at Jefferson Lab

The Super High Momentum Spectrometer (SHMS) has been built for Hall C at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). With a momentum capability reaching 11 GeV/ c , the SHMS provides measurements of charged particles produced in electron-scattering experiments using the maximum available beam energy from the upgraded Jefferson Lab accelerator. The SHMS is an ion-optics magnetic spectrometer comprised of a series of new superconducting magnets which transport charged particles through an array of triggering, tracking, and particle-identification detectors that measure momentum, energy, angle and position in order to allow kinematic reconstruction of the events back to their origin at the scattering target. The detector system is protected from background radiation by a sophisticated shielding enclosure. The entire spectrometer is mounted on a rotating support structure which permits measurements to be taken with a large acceptance over laboratory scattering angles from 5.5° to 40°, thus allowing a wide range of low cross-section experiments to be conducted. Finally, these experiments complement and extend the previous Hall C research program to higher energies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Analysis of high-resolution spectra from a hybrid interferometric/dispersive spectrometer

To fully take advantage of a low-cost, small footprint hybrid interferometric/dispersive spectrometer, a math- ematical reconstruction technique was developed to accurately capture the high-resolution and relative peak intensities from complex patterns. A Fabry-Perot etalon was coupled to a Czerny-Turner spectrometer, in- creasing spectral resolution by an order of magnitude without the commensurate increase in spectrometer size. Measurement of the industry standard Hg 313.1555/313.1844 nm doublet yielded a ratio of 0.682 with 1.8%error, which agreed well with an independent measurement and literature values. The doublet separation (29 pm), is similar to the U isotope shift (25 pm) at 424.437 nm that is of interest to monitoring nuclear nonpro-liferation activities. Additionally, the technique was applied to a LIBS measurement of the mineral cinnabar (HgS) and resulted in a ratio of 0.681. In addition, this reconstruction method could enable significantly smaller, portable high-resolution instruments with isotopic specificity, benefiting a variety of spectroscopic applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2010

A high resolution, broad energy acceptance spectrometer for laser wakefield acceleration experiments

Laser wakefield experiments present a unique challenge in measuring the resulting electron energy properties due to the large energy range of interest, typically several 100 MeV, and the large electron beam divergence and pointing jitter >1 mrad. In many experiments the energy resolution and accuracy are limited by the convolved transverse spot size and pointing jitter of the beam. In this paper we present an electron energy spectrometer consisting of two magnets designed specifically for laser wakefield experiments. In the primary magnet the field is produced by permanent magnets. A second optional electromagnet can be used to obtain better resolution for electron energies above 75 MeV. The spectrometer has an acceptance of 2.5-400 MeV (E{sub max}/E{sub min}>100) with a resolution of better than 1% rms for electron energies above 25 MeV. This high resolution is achieved by refocusing electrons in the energy plane and without any postprocessing image deconvolution. Finally, the spectrometer employs two complimentary detection mechanisms: (1) absolutely calibrated scintillation screens imaged by cameras outside the vacuum chamber and (2) an array of scintillating fibers coupled to a low-noise charge-coupled device.

43 PARTICLE ACCELERATORS↗