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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The Giotto dust impact detection system

The Giotto Dust Impact Detection System (DIDSY) consists of six independent subsystems to register the impact of all particulates of significant mass incident on the probe during the post-perihelion encounter with Comet Halley. Mounted on Giotto's front dust shield, the detectors will determine the mass spectrum of the dust, with a limiting sensitivity of 10 to the minus 17th power f, increasing to the largest grain masses encountered along Giotto's trajectory throught the cometary environment with an ultimate spatial resolution of 70 km. An additional detector is located on the rear shield to monitor dust particles that penetrate the from dust shield. An ambient plasma monitor measures the impact plasma generated by dust and gass impacts on the spacecraft.

Mcdonnell, J. A. M.↗
DOE OSTI2026

Muon tracking in a LiquidO opaque scintillator detector

LiquidO is an innovative radiation detector concept. The core idea is to exploit stochastic light confinement in a highly scattering medium to self-segment the detector volume. In this paper, we demonstrate event-by-event muon tracking in a LiquidO opaque scintillator detector prototype. The detector consists of a 30 mm cubic scintillator volume instrumented with 64 wavelength-shifting fibres arranged in an 8 × 8 grid with a 3.2 mm pitch and read out by silicon photomultipliers. A wax-based opaque scintillator with a scattering length of approximately 0.5 mm is used. The tracking performance of this LiquidO detector is characterised with cosmic-ray muons and the position resolution is demonstrated to be 450 μm per row of fibres. These results highlight the potential of LiquidO opaque scintillator detectors to achieve fine spatial resolution, enabling precise particle tracking and imaging.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRSDate not supplied

AstroPix: ATLAS-Inspired Silicon Pixels for Future Space-Based Gamma-ray Telescopes

Space-based gamma-ray telescopes such as the Fermi Large Area Telescope have used single sided silicon strip detectors to measure the position of incident gamma-rays with high resolution. At lower energies, two dimensional position information within a single detector is required. This talk investigates the use of monolithic CMOS active pixel silicon sensors –AstroPix – as a novel technology for use in future gamma-ray telescopes. Based upon detectors designed for use in the ATLAS detector at the LHC, AstroPix has the potential to maintain the high energy and angular resolution required of a medium-energy gamma-ray telescope while reducing noise with the dual detection and readout capabilities of a CMOS chip. The status of AstroPix development and testing, as well as outlook for application in future telescopes such as the proposed medium-energy gamma-ray telescope AMEGO-X, will be presented.

Amanda L. Steinhebel↗
NASA NTRS2019

GaN/AlGaN Avalanche Photodiode Detectors for High Performance Ultraviolet Sensing Applications

The shorter wavelengths of the ultraviolet (UV) band enable detectors to operate with increased spatial resolution, variable pixel sizes, and large format arrays, benefitting a variety of NASA, defense, and commercial applications. AlxGa1-xN semiconductor alloys, which have attracted much interest for detection in the UV spectral region, have been shown to enable high optical gains, high sensitivities with the potential for single photon detection, and low dark current performance in ultraviolet avalanche photodiodes (UV-APDs). We are developing GaN/AlGaN UV-APDs with large pixel sizes that demonstrate consistent and uniform device performance and operation. These UV-APDs are fabricated through high quality metal organic chemical vapor deposition (MOCVD) growth on lattice-matched, low dislocation density GaN substrates with optimized material growth and doping parameters. The use of these low defect density substrates is a critical element to realizing highly sensitive UV-APDs and arrays with suppressed dark current under high electric fields.Optical gains greater than 5X10 (exp 6) with enhanced quantum efficiencies over the 350-400 nm spectral range have been demonstrated, enabled by a strong avalanche multiplication process. Furthermore, we are developing 6X6 arrays of devices to test high gain UV-APD array performance at ~355 nm. These variable-area GaN/AlGaN UV-APD detectors and arrays enable advanced sensing performance over UV bands of interest with high resolution detection for NASA Earth Science applications.

Sood, Ashok K.↗
DOE OSTI2024

Three Photon Excited Image Scanning Microscopy for in-Depth Super-Resolution Studies of Biological Samples

Multiphoton laser scanning microscopy is a powerful tool for deep imaging of thick biological samples. Image scanning microscopy (ISM) has demonstrated significant improvements in the signal-to-noise ratio in confocal laser scanning microscopy, while at the same time improving upon the effectively attainable resolution. Two-photon excitation (2PE), combined with ISM, has been shown to allow for deep tissue imaging with enhanced resolution compared to 2PE microscopy. Three-photon excitation (3PE) has enabled record imaging depth and contrast for multiphoton imaging, due to the superior suppression of out-of-focus signal generation. In this paper, we demonstrate super-resolution 3PE ISM. This is achieved using a single-photon avalanche detector array, and 1040-nm pulses for 3PE of blue fluorescence. This method enables subdiffraction limited resolution imaging of biological samples stained with blue fluorescent markers, such as mouse myocardial and spinal cord tissues stained with 4 ′ , 6 -diamidino-2-phenylindole. Deconvolution improves the resolving power further and allows for imaging with better than λ / 8 resolution with respect to the 3PE wavelength λ . With the ISM pixel reassignment procedure, we demonstrate a resolution enhancement of ∼ 1.6 laterally, compared to the resolution attained using a photomultiplier tube in a non-descanned detection arrangement, and a factor of ∼ 1.8 enhancement in axial resolution. The experimentally measured three-dimensional point spread function volume is shrunk ∼ 4.4 -fold, which is close to the theoretically expected enhancement. Published by the American Physical Society 2024

47 OTHER INSTRUMENTATION↗
NASA NTRS2002

Charge Sharing and Charge Loss in a Cadmium-Zinc-Telluride Fine-Pixel Detector Array

Because of its high atomic number, room temperature operation, low noise, and high spatial resolution a Cadmium-Zinc-Telluride (CZT) multi-pixel detector is ideal for hard x-ray astrophysical observation. As part of on-going research at MSFC (Marshall Space Flight Center) to develop multi-pixel CdZnTe detectors for this purpose, we have measured charge sharing and charge loss for a 4x4 (750micron pitch), lmm thick pixel array and modeled these results using a Monte-Carlo simulation. This model was then used to predict the amount of charge sharing for a much finer pixel array (with a 300micron pitch). Future work will enable us to compare the simulated results for the finer array to measured values.

Gaskin, J. A.↗
DOE OSTI2023

Towards robust PICOSEC Micromegas precise timing detectors

The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector consisting of a Cherenkov radiator combined with a photocathode and a MM amplifying structure. A 100-channel PICOSEC MM prototype with 10 × 10 cm 2 active area equipped with a Cesium Iodide (CsI) photocathode demonstrated a time resolution below σ = 18 ps. The objective of this work is to improve the PICOSEC MM detector robustness aspects, i.e. integration of resistive MM and carbon-based photocathodes, while maintaining good time resolution. The PICOSEC MM prototypes have been tested in laboratory conditions and successfully characterised with 150 GeV/c muon beams at the CERN SPS H4 beam line. The excellent timing performance below σ = 20 ps for an individual pad obtained with the 10 × 10 cm 2 area resistive PICOSEC MM of 20 MΩ/$\square$ showed no significant time resolution degradation as a result of adding a resistive layer. A single-pad prototype equipped with a 12 nm thick Boron Carbide (B 4 C) photocathode presented a time resolution below σ = 35 ps, opening up new possibilities for detectors with robust photocathodes. The results made the concept more suitable for the experiments in need of robust detectors with good time resolution.

RETHGEM↗
DOE OSTI2021

A 90 ° bend curved light-guide for TOF scintillating detectors

We report here a bench study of TOF resolution using a 90° bend curved solid light-guide (LG) used to transport the light from a plastic scintillator counter to a photomultiplier (PMT). The 90° LG allows the rotation of the PMT axis to be vertical to the detector axis, in an environment featured by a strong magnetic field along the detector surface, or other geometrical constrains. We show that with a TOF counter of 2000 x 100 x 60 mm 3 and light read-out by PMTs at its two 100 × 60 mm 2 sides, when 90° LG benders are used between the scintillating bar and the PMTs on both sides, the TOF resolution is worsen, by 5–10%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1986

Capacitor-type micrometeoroid detectors

The metal oxide semiconductor (MOS) capacitor micrometeroid detector consists of a thin dielectric capacitor fabricated on a silicon wafer. In operation, the device is charged to a voltage level sufficiently near breakdown that micrometeoroid impacts will cause dielectric deformation or heating and subsequent arc-over at the point of impact. Each detector is capable of recording multiple impacts because of the self-healing characteristics of the device. Support instrumentation requirements consist of a voltage source and pulse counters that monitor the pulse of recharging current following every impact. An investigation has been conducted in which 0.5 to 5 micron diameter carbonized iron spheres traveling at velocities of 4 to 10 Km/sec were impacted on to detectors with either a dielectric thickness of 0.4 or 1.0 micron. This study demonstrated that an ion microprobe tuned to sufficiently high resolution can detect Fe remaining on the detector after the impact. Furthermore, it is also possible to resolve Fe ion images free of mass interferences from Si, for example, giving its spatial distribution after impact. Specifically this technique has shown that significant amounts of impacting particles remain in the crater and near it which can be analyzed for isotopic content. Further testing and calibration could lead to quantitive analysis. This study has shown that the capacitor type micrometeroid detector is capable of not only time and flux measurements but can also be used for isotopic analysis.

Wortman, J. J.↗
DOE OSTI2020

Expectation-propagation for weak radionuclide identification at radiation portal monitors

We propose a sparsity-promoting Bayesian algorithm capable of identifying radionuclide signatures from weak sources in the presence of a high radiation background. The proposed method is relevant to radiation identification for security applications. In such scenarios, the background typically consists of terrestrial, cosmic, and cosmogenic radiation that may cause false positive responses. We evaluate the new Bayesian approach using gamma-ray data and are able to identify weapons-grade plutonium, masked by naturally-occurring radioactive material (NORM), in a measurement time of a few seconds. We demonstrate this identification capability using organic scintillators (stilbene crystals and EJ-309 liquid scintillators), which do not provide direct, high-resolution, source spectroscopic information. Compared to the EJ-309 detector, the stilbene-based detector exhibits a lower identification error, on average, owing to its better energy resolution. Organic scintillators are used within radiation portal monitors to detect gamma rays emitted from conveyances crossing ports of entry. The described method is therefore applicable to radiation portal monitors deployed in the field and could improve their threat discrimination capability by minimizing “nuisance” alarms produced either by NORM-bearing materials found in shipped cargoes, such as ceramics and fertilizers, or radionuclides in recently treated nuclear medicine patients.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS2000

Imaging Calorimeter for ACCESS Simulations with GEANT/FLUKA

Imaging Calorimeter for ACCESS (ICA) is a candidate of the calorimeter for the NASA's ACCESS program. The ICA studies the origin and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays in the energy up to 10(exp 16) eV. For the past year, Monte Carlo simulation study for the ICA has been conducted to predict the detector performance and to design the system for match the scientific objectives. Simulation results show that the detector response resembles a Gaussian distribution and the energy resolution with ICA can be achieved about 40%. In addition, simulations of the detector's response to an assumed bent power law spectra in the region where the knee occurs have been conducted and clearly show that this detector can provide sufficiently accurate estimates of the spectral parameters that are a science goal of ACCESS.

Lee, Jeongin↗
DOE OSTI2025

High-resolution in-situ characterization of laser powder bed fusion via transmission X-ray microscopy at X-ray free electron lasers

In this work, we describe the instrumentation used to perform the first operando transmission X-ray microscopy (TXM) and simultaneous X-ray diffraction of laser melting simulating laser powder bed fusion on the XCS instrument at the Linac Coherent Light Source (LCLS) X-ray free-electron laser (XFEL). Our TXM with 40× magnification in the X-ray regime at 11 keV gave spatial resolutions down to 940 nm per line pair, with effective pixel sizes down to 206 nm, image integration times of <100 fs, and frame rates tunable between 2.1 and 119 ns for two probe frames (0.48 GHz to 8.4 MHz). Images were recorded on Zyla and Icarus (UXI) detectors to trade off between spatial resolution and time dynamics. A 1 kW CW IR laser was coupled into the interaction point to conduct pump–probe studies of laser melting and solidification dynamics. Our temporal and spatial resolution with attenuation-based contrast exceeds that currently possible with synchrotron-based high-speed radiography. This system was sensitive to feature velocities of 10–12000 m s −1 but we did not observe any motion in this range in the laser melting of Al6061 alloy. Shockwaves were not observed and hot cracking proceeded at velocities below the detection limits. Pore accumulation was observed between successive shots, indicating that bubble escape mechanisms were not active. With proper experimental design, the spatial resolution, contrast and field of view could be further improved or modified. The increased brightness and narrower bandwidth of the XFEL allowed for this imaging technique and it lays the groundwork for a wide range of operando techniques to study additive manufacturing.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Sub-25 ps timing measurements with 10 × 10 cm 2 PICOSEC Micromegas detectors

The PICOSEC Micromegas detector is a precise timing gaseous detector based on a Cherenkov radiator coupled to a semi-transparent photocathode and a Micromegas amplifying structure. First single-pad prototypes demonstrated a time resolution below σ = 25 ps, however, to make the concept appropriate to physics applications, several developments are required. The objective of this work was to achieve an equivalent time resolution for a 10 × 10 cm 2 area PICOSEC Micromegas detector. The prototype was designed, produced and tested in the laboratory and successfully operated with a 80 GeV/c muon beam. Preliminary results for this device equipped with a CsI photocathode demonstrated a time resolution below σ = 25 ps for all measured pads. The time resolution was reduced to be below σ = 18 ps by decreasing the drift gap to 180 μm and using dedicated RF amplifier cards as new electronics. The excellent timing performance of the single-channel proof of concept was not only transferred to the 100-channel prototype, but even improved, making the PICOSEC Micromegas detector more suitable for large-area experiments in need of detectors with high time resolutions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

SINGLE: Atomic-resolution structure identification of nanocrystals by graphene liquid cell EM

Analysis of the three-dimensional (3D) structures of nanocrystals with solution-phase transmission electron microscopy is beginning to reveal their unique physiochemical properties. We developed a “one-particle Brownian 3D reconstruction method” based on imaging of ensembles of colloidal nanocrystals using graphene liquid cell electron microscopy. Projection images of differently rotated nanocrystals are acquired using a direct electron detector with high temporal (<2.5 ms) resolution and analyzed to obtain an ensemble of 3D reconstructions. Here, we introduce computational methods required for successful atomic-resolution 3D reconstruction: (i) tracking of the individual particles throughout the time series, (ii) subtraction of the interfering background of the graphene liquid cell, (iii) identification and rejection of low-quality images, and (iv) tailored strategies for 2D/3D alignment and averaging that differ from those used in biological cryo–electron microscopy. Our developments are made available through the open-source software package SINGLE.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRSDate not supplied

Design and Performance of the Hitomi/XRISM Adiabatic Demagnetization Refrigerator Controller

The Resolve instrument in the recently launched X-ray Imaging and Spectroscopy Mission (XRISM) is a rebuild of the Soft X-ray Spectrometer (SXS) in Hitomi (aka Astro-H which had an unfortunately brief mission life in 2016). It is a high-resolution non-dispersive soft x-ray spectrometer from nominally 0.3 keV to 12 keV based on a calorimeter detector array operating at 50 mK with a resolution better than 7 eV FWHM at 6 keV. For such sensitive cryogenic instruments, temperature stability has a strong impact on the detector’s performance. The Adiabatic Demagnetization Refrigerator Controller (ADRC) in the XRISM Resolve instrument is an electronics box responsible for high-precision sub-K temperature readout and control of the multi-stage adiabatic demagnetization refrigerator subsystem to achieve a thermal stability better than 2.5 uK RMS (over a 10-minute interval) for the calorimeter detectors in both cryogen (liquid helium) and cryo-free modes. It has direct telemetry/command and power interfaces with the spacecraft. It also provides sensor read-out and heater circuits for decontamination of the filters in the cold aperture. As a part of the discussion on the design and performance of the ADRC, this paper will also include an overall view of the 50 mK temperature control, plus monitor and control of the aperture filter temperature for de-contamination purpose.

ADRC↗
NASA NTRSDate not supplied

Design and Performance of the Hitomi/XRISM Adiabatic Demagnetization Refrigerator Controller

The Resolve instrument in the recently launched X-ray Imaging and Spectroscopy Mission (XRISM) is a rebuild of the Soft X-ray Spectrometer (SXS) in Hitomi (aka Astro-H which had an unfortunately brief mission life in 2016). It is a high-resolution non-dispersive soft x-ray spectrometer from nominally 0.3 keV to 12 keV based on a calorimeter detector array operating at 50 mK with a resolution better than 7 eV FWHM at 6 keV. For such sensitive cryogenic instruments, temperature stability has a strong impact on the detector’s performance. The Adiabatic Demagnetization Refrigerator Controller (ADRC) in the XRISM Resolve instrument is an electronics box responsible for high-precision sub-K temperature readout and control of the multi-stage adiabatic demagnetization refrigerator subsystem to achieve a thermal stability better than 2.5 uK RMS (over a 10-minute interval) for the calorimeter detectors in both cryogen (liquid helium) and cryo-free modes. It has direct telemetry/command and power interfaces with the spacecraft. It also provides sensor read-out and heater circuits for decontamination of the filters in the cold aperture. As a part of the discussion on the design and performance of the ADRC, this paper will also include an overall view of the 50 mK temperature control, plus monitor and control of the aperture filter temperature for de-contamination purpose.

ADRC↗
DOE OSTI2020

A Scintillating Xenon Bubble Chamber for Dark Matter Detection. Final Report

This report describes the progress in the search for particle dark matter achieved under DOE award DE-SC0012161, as well as the invention of a new dark matter and neutrino detection technique. Work supported by this award follows in three distinct thrusts: (1) the successful completion of the Generation-1 Direct Detection experiment PICO-60, which set the world-leading limit on the spin-dependent coupling of dark matter to protons and achieved a precise understanding of the response of bubble chambers to nuclear-recoil signals and electron-recoil backgrounds; (2) the construction of the Generation-2 Direct Detection experiment LZ, which will soon be the world's most sensitive dark matter detector; and (3) the demonstration of the first scintillating bubble chamber. The development of a scintillating liquid noble bubble chamber was the primary goal of the proposed work, with the aim of combining the excellent background rejection of a PICO-style bubble chamber with the event-by-event energy resolution of a liquid-noble detector such as LZ. This work produced the first ever observation of coincident scintillation and bubble nucleation by a nuclear recoil in a superheated fluid and also revealed an unexpected benefit to the use of noble liquids in a bubble chamber, namely the ability to increase the degree of superheat by an order of magnitude beyond that achievable in PICO-style detectors while maintaining PICO's world-leading background rejection. This discovery has led to new projects in the US and Canada, developing noble liquid bubble chambers both as detectors for low-mass dark matter and as detectors of coherent elastic neutrino-nucleus scattering (CEvNS) by neutrinos produced at nuclear reactors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1997

High-resolution spectral measurements of GRO J1655-40

Data from the transient gamma ray germanium detector taken during 1995 provide a limited ability to study the high resolution spectrum of the X-ray transient GRO J1655-40. During a two-day period around the peak intensity, the soft spectrum was measured and found to be consistent with a power law spectrum with photon index -3.0 +/- 0.2. No evidence was found for narrow spectral features in the 50 to 100 keV band or around 511 keV. The 3 sigma upper limit for a narrow emission line at 511 keV is 1.2 x 10(exp -2) phot/cu cm s.

intZand, J. J. M.↗