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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

α-Particle Detection and Charge Transport Characteristics in the A 3 M 2 I 9 Defect Perovskites (A = Cs, Rb; M = Bi, Sb)

Here, we have investigated the defect perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb) as materials for radiation detection. The phase purity of Bridgman-grown A 3 M 2 I 9 single crystals was confirmed via high-resolution synchrotron X-ray diffraction, while density functional theory calculations (DFT) show surprisingly dispersive bands in the out-of-plane direction for these layered materials, with low effective masses for both holes and electrons. Accordingly, each of the four A 3 M 2 I 9 defect perovskites showed response to 241 Am α-particle irradiation for hole and electron electrode configurations, a remarkable ambipolar response that resembles the 3D halide perovskites. The electron response spectra were used to estimate the mobility–lifetime product (μτ) e for electrons in these materials, with Rb 3 Bi 2 I 9 showing the lowest (μτ) e value of 1.7 × 10 – 6 cm 2 V –1 and Cs 3 Bi 2 I 9 the highest (μτ) e of 5.4 × 10 –5 cm 2 V –1 . The rise time of the α-particle-generated pulse was used to estimate the electron mobility μ e of the A 3 M 2 I 9 defect perovskites, which ranged from 0.32 cm 2 V –1 s–1 for Rb 3 Sb 2 I 9 to 4.3 cm 2 V –1 s –1 in Cs 3 Bi 2 I 9 . Similar analysis of the hole response spectra yielded (μτ) h values for each A 3 M 2 I 9 compound, with Cs 3 Bi 2 I 9 again showing the highest (μτ) h value of 1.8 × 10 –5 cm 2 V –1 , while Rb 3 Bi 2 I 9 showed the lowest (μτ) h with 2.0 × 10 –6 cm 2 V –1 . Rise time analysis gave hole mobilities ranging from 1.7 cm 2 V –1 s –1 for Cs 3 Bi 2 I 9 to 0.14 cm 2 V –1 s –1 for Cs 3 Sb 2 I 9 . Comparing the experimental electron and hole mobilities to the effective masses obtained from DFT calculations revealed sizable discrepancies, possibly indicating self-trapping of charge carriers due to electron–phonon interactions. The α-particle response of the A 3 M 2 I 9 defect perovskites demonstrates their potential as semiconductor radiation detectors, with Cs 3 Bi 2 I 9 and Cs 3 Sb 2 I 9 showing the most promise.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

β -Delayed Neutron Spectroscopy Using Trapped Radioactive Ions

Here, a novel technique for β-delayed neutron spectroscopy has been demonstrated using trapped ions. The neutron-energy spectrum is reconstructed by measuring the time of flight of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection, such as backgrounds from scattered neutrons and γ rays and complicated detector-response functions. 137 I + ions delivered from a 252 Cf source were confined in a linear Paul trap surrounded by radiation detectors, and the β-delayed neutron-energy spectrum and branching ratio were determined by detecting the β - and recoil ions in coincidence. Systematic effects were explored by determining the branching ratio three ways. Improvements to achieve higher detection efficiency, better energy resolution, and a lower neutron-energy threshold are proposed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Radiation Mapping for an Unmanned Aerial Vehicle: Development and Simulated Testing of Algorithms for Source Mapping and Navigation Path Generation

Image reconstruction algorithms were developed for radiation source mapping and used for generating the search path of a moving radiation detector, such as one onboard an unmanned aerial vehicle. Simulations consisted of first assuming radioactive sources of varying complexity and estimating the radiation fields that would then be produced by that source distribution. Next, the "measurements" that would result from a pair of adjacent spatial locations were computed. A crude estimate of the source distribution likely to have produced such "measurements" was reconstructed based upon the limited measurements. Location of the next "measurement" was then determined as halfway between the location of the estimated source and the current "measurement." With each additional sample, improved source distribution reconstructions were made and used to inform the immediate direction of detector motion. Source reconstruction or mapping was formulated as an inverse problem solved with either maximum a posteriori or least squares (LS) regression deconvolution methods. Different amounts of noise were added to the simulated "measurements," allowing evaluation of the methods' performances as functions of signal-to-noise ratio of the measured map. As expected, methods that promote sparsity were better suited in reconstructing point sources. Reliable prior information of the source distribution also improved the reconstruction results, especially with distributed sources. With a non-negative least square algorithm and the suggested paths it generated, location of sources was successfully estimated to an accuracy of 0.014 m within nine iterations in a single-source scenario and 12 iterations in a two-source scenario, given a 10% error on the integrated counts and a Poisson distribution of the noise associated with the measured counts.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2023

Large-volume CdZnTe bar detectors characterized by laser-induced transient currents

In this work, we studied the free-carrier transport properties and space-charge formation/polarization in a CdZnTe bar-shaped radiation detector using the Laser-Induced Transient Current technique. We found out that a steady-state space charge ranging from 8 x 10 8 to 2.1 x 10 9 cm -3 is formed throughout the detector at about 0.5 s following biasing. The measured current waveforms were modeled by Monte Carlo simulations after taking into account the electric and weighting fields inside the detector and shielding box. Modeling of the unpolarized waveforms revealed an exceptionally high electron mobility-lifetime product μ e τ e ≥0.095cm 2 V -1 . The observed formation of positive space charge in the biased detector and linear scaling of the current waveform shapes on applied bias revealed that the detector polarization is attributed to carrier injection at the anode. In conclusion, measurements in pulsed and DC bias in modified electrode geometry proved the surface-charge formation.

47 OTHER INSTRUMENTATION↗
NASA NTRS2015

Detection of DNA Damage by Space Radiation in Human Fibroblast Cells Flown on the International Space Station

Although charged particles in space have been detected with radiation detectors on board spacecraft since the early discovery of the Van Allen Belt, reports on effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation has been difficult due to the low dose and low dose rate nature of the radiation environment, and the difficulty in separating the radiation effects from microgravity and other space environmental factors. In astronauts, only a small number of changes, such as increased chromosome aberrations in lymphocytes and early onset of cataracts, attributed primarily to the exposure to space radiation. In a recent experiment, human fibroblast cells were flown on the International Space Station (ISS). Cells fixed on Days 3 and 14 after reaching orbit were analyzed for phosphorylation of a histone protein H2AX by immunofluorescent staining of cells, which is a widely used marker for DNA double strand breaks. The 3-dimensional gamma-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed a small fraction of foci that were larger and displayed a track pattern in the flight samples in comparison to the ground control. Human fibroblast cells were also exposed to low dose rate gamma rays, as well as to protons and Fe ions. Comparison of the pattern and distribution of the foci after gamma ray and charged particle exposure to our flight results confirmed that the foci found in the flown cells were indeed induced by space radiation.

Wu, Honglu↗
NASA NTRS2017

Detection of DNA Damage by Space Radiation in Human Fibroblasts Flown on the International Space Station

Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation. In this study, cultured human fibroblasts were flown on the International Space Station (ISS). Cells were kept at 37 degrees Centigrade in space for 14 days before being fixed for analysis of DNA damages with the gamma-H2AX assay. The 3-dimensional gamma-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed several foci that were larger and displayed a track pattern only in the Day 14 flight samples. To confirm that the foci data from the flight study was actually induced from space radiation exposure, cultured human fibroblasts were exposed to low dose rate gamma rays at 37 degrees Centigrade. Cells exposed to chronic gamma rays showed similar foci size distribution in comparison to the non-exposed controls. The cells were also exposed to low- and high-LET (Linear Energy Transfer) protons, and high-LET Fe ions on the ground. Our results suggest that in G1 human fibroblasts under the normal culture condition, only a small fraction of large size foci can be attributed to high-LET radiation in space.

Lu, Tao↗
DOE OSTI2017

Nuclear Smuggling Detection and Deterrence FY 2016 Data Analysis Annual Report

The National Nuclear Security Administration’s Office of Nuclear Smuggling Detection and Deterrence (NSDD) has facilitated the installation of more than 3,500 radiation portal monitors (RPMs) at 606 sites in 56 countries worldwide. This collection of RPMs represents the world’s largest network of radiation detectors and provides one element in the defense-in-depth approach that supports the Global Nuclear Detection Architecture. These systems support NSDD’s mission to build partner country capability to deter, detect, and interdict the illicit transport of radiological and fissile material through strategic points of entry and exit at seaports, airports, and border crossings. NSDD works collaboratively with partner countries and international organizations to optimize the operation of these RPMs. The large amount of data provided by NSDD partner countries highlights the close cooperation and partnerships NSDD has built with 56 countries around the world. Thirty-seven of these countries shared at least some RPM-related data with NSDD in fiscal year 2016. This significant level of data sharing is a key element that distinguishes the NSDD office as unique among nuclear nonproliferation programs and initiatives: NSDD can provide specific, objective, data-driven decisions and support for sustaining the radiation detection systems it helped deploy. This data analysis report summarizes and aggregates the RPM data provided to the NSDD office for analysis and review in fiscal year 2016. The data can be used to describe RPM performance and characterize the wide diversity of NSDD deployment sites. For example, NSDD deploys detector systems across sites with natural background radiation levels that can vary by a factor of approximately six from site to site. Some lanes have few occupancies, whereas others have approximately 8,000 occupancies per day and the different types of cargo that travel through a site can result in site-wide alarm rates that range from near 0% at some sites to above 3% at others. Based on the data received, the global average uptime for NSDD RPMs was above 96% for fiscal year 2016. NSDD takes all of these factors into account in making recommendations to partner countries on how to most effectively manage and maintain site operations. NSDD utilizes reports and other information products created by data analysts to efficiently allocate the resources needed to detect and ultimately interdict illicit nuclear and radiological material.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

Nuclear Smuggling Detection and Deterrence (FY 2018 Data Analysis Annual Report)

The National Nuclear Security Administration’s Office of Nuclear Smuggling Detection and Deterrence (NSDD) has facilitated the installation of more than 3,728 radiation portal monitors (RPMs) at 660 sites in 63 countries. This collection of RPMs represents the world’s largest network of radiation detectors and provides one element of the defense-in-depth approach that supports the Global Nuclear Detection Architecture. These systems support NSDD’s mission to build partner country capability to deter, detect, and interdict the illicit transport of radiological and fissile material through strategic points of entry and exit at seaports, airports, and border crossings.NSDD works collaboratively with partner countries and international organizations to optimize the operation of these RPMs. The large amount of data provided by NSDD partner countries (summarized in the banner to the right) highlights the close cooperation and partnerships NSDD has built with 63 countries around the world. Thirty-two of these countries shared at least some RPM-related data with NSDD in fiscal year (FY) 2018. This significant level of data sharing is a key element that distinguishes the NSDD office as unique among nuclear nonproliferation programs and initiatives: NSDD can provide specific, objective, data-driven decisions and support for sustaining the radiation detection systems it helped deploy. This data analysis report summarizes and aggregates the RPM data provided to the NSDD office for analysis and review in FY 2018.The data can be used to describe RPM performance and characterize the wide diversity of NSDD deployment sites. For example, NSDD deploys detector systems across sites with natural background radiation levels that can vary by a factor of up to nine from site to site. Some RPM lanes have few occupancies, whereas others have up to approximately 8,000 occupancies per day, and the different types of cargo traveling through a site can result in site-wide alarm rates that range from near 0% at some sites to above 3% at others. Based on the data received, the global average uptime for NSDD RPMs was 97% for FY 2018. NSDD takes all these factors into account in making recommendations to partner countries on how to most effectively manage and maintain site operations. NSDD utilizes reports and other information products created by ORNL Radiation Inspection Systems Team (RIST) data analysts to efficiently allocate the resources needed to detect and ultimately interdict illicit nuclear and radiological material.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2023

INTEGRATION OF THE H3D-M400 DETECTOR AND SPOT ROBOT FOR AUTOMATED AREA SURVEY MISSIONS

Office of Nuclear Smuggling Detection and Deterrence (NSDD) is charged to identify and develop technologies to detect, disrupt, and investigate smuggling of radiological and nuclear materials •Border protection involves primary inspections using Radiation Portal Monitors (RPM), complimented with secondary and area survey inspections, usually performed manually using portable radiation detectors (PRDs) -RPM rely on fast technologies which provide quick scans of passing cargo/vehicles -Secondary inspections rely on trained, field deployed staff responsible for additional interdiction of screened cargo/vehicle putting them in potentially hazardous environment -Area survey inspections rely on trained, field deployed staff responsible for scanning and identifying presence of radiation while patrolling through a facility or public space •This project explores the use of technology which could reduce risks to field inspectors and add efficiency •The work presented here is a proof of principle of detector-robot integration to perform area survey inspections

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
NASA NTRS2013

Fast, Large-Area, Wide-Bandgap UV Photodetector for Cherenkov Light Detection

Due to limited resources available for power and space for payloads, miniaturizing and integrating instrumentation is a high priority for addressing the challenges of manned and unmanned deep space missions to high Earth orbit (HEO), near Earth objects (NEOs), Lunar and Martian orbits and surfaces, and outer planetary systems, as well as improvements to high-altitude aircraft safety. New, robust, and compact detectors allow future instrumentation packages more options in satisfying specific mission goals. A solid-state ultraviolet (UV) detector was developed with a theoretical fast response time and large detection area intended for application to Cherenkov detectors. The detector is based on the wide-bandgap semiconductor zinc oxide (ZnO), which in a bridge circuit can detect small, fast pulses of UV light like those required for Cherenkov detectors. The goal is to replace the role of photomultiplier tubes in Cherenkov detectors with these solid-state devices, saving on size, weight, and required power. For improving detection geometry, a spherical detector to measure high atomic number and energy (HZE) ions from any direction has been patented as part of a larger space radiation detector system. The detector will require the development of solid-state UV photodetectors fast enough (2 ns response time or better) to detect the shockwave of Cherenkov light emitted as the ions pass through a quartz, sapphire, or acrylic ball. The detector must be small enough to fit in the detector system structure, but have an active area large enough to capture enough Cherenkov light from the sphere. The detector is fabricated on bulk single-crystal undoped ZnO. Inter - digitated finger electrodes and contact pads are patterned via photolithography, and formed by sputtered metal of silver, platinum, or other high-conductivity metal.

Wrbanek, John D.↗
NASA NTRS1974

The efficient identification of relativistic particles by transition radiation

A system of transition radiation detectors has been constructed and exposed to beams of electrons and pions in the energy range of 3 to 15 GeV at SLAC. Transition radiation was generated in a variety of stacks of mylar foils (radiators), and its intensity was detected with 7 multiwire proportional chambers. The raw data demonstrate a good separation between electron and pion induced signals. A more detailed analysis shows that a very efficient identification of individual particles is possible. Typically, a detection efficiency for electrons above 90%, combined with a pion-electron discrimination ratio of .001, has been achieved. Some conclusions with respect to the design of a practical detector for relativistic particles are drawn.

Cherry, M. L.↗
NASA NTRS1985

Measurement of the characteristic X ray of oxygen and other ultrasoft X rays using mercuric iodide detectors

This letter reports the detection and resolution of the characteristic X-ray of oxygen at 523 eV and other ultrasoft X-rays (photons energy less than 1 keV) using radiation detectors fabricated from the compound semi-insulator mercuric iodide (HgI2). These detectors are capable of operation at room ambient but in these experiments were slightly cooled using a Peltier element to 0 C. A pulsed light feedback preamplifier with a Peltier element cooled (to -30 deg) first stage field-effect transistor was used to amplify signals from the detector. Overall system noise level was 185 eV (full width at half-maximum) limited by the temperature of the first stage field-effect transistor. With optimal cooling of this element the characteristic X-ray of carbon at 282 eV should be measurable. These results would seem to be important in measurement of biological samples in electron column instruments.

Iwanczyk, J. S.↗
NASA NTRS1985

Detectors for high energy cosmic rays on Spacelab

Two instruments designed to determine the spectra of the individual cosmic-ray components at very high energies are described. One of these (CRNE) uses a combination of gas Cerenkov counters and transition radiation detectors for the cosmic-ray nuclei lithium to nickel; the other (TRIC) is optimized for the light cosmic rays (electrons, protons, helium) and uses a transition-radiation/ionization-calorimeter combination. The CRNE instrument, constructed at the University of Chicago, was delivered to NASA for a first Shuttle flight on Spacelab-2 in summer 1985. Some of the technical and programmatic requirements encountered during the hardware construction and integration are discussed, and the expected scientific return and the prospects of using such instrumentation on the Space Station are considered.

Lheureux, J.↗
NASA NTRS1986

First results from Spacelab 2

Preliminary results of physical experiments carried out during the Spacelab 2 Shuttle mission are summarized. Attention is given to experiments in the fields of plasma dynamics; solar physics; high-energy astrophysics; and astronomy. Plasma experiments included an ejectable plasma diagnosics package and measurements of the passive charging of the Shuttle vehicle in the surrounding space plasma. The solar physics instrument package consisted of a solar spectral irradiance monitor; a solar optical universal polarimeter (SOUP); and a solar helium abundance high-resolution telescope and spectrograph (HRTS). Astronomical observations were performed using a scanning infrared telescope (IRT) which consisted of a highly baffled herschelian telescope and 10 detectors covering wavelengths from 2 to 120 microns. Cosmic-ray nuclei were detected and analyzed using gas Cerenkov counters and a transition radiation detector. Addition experiments included a thin film fluid dynamics payload and analysis of blood samples taken from the mission specialists. Complete data records from the experiments have now been distributed for an analysis period which will take at least a year. A table listing the Spacelab 2 experiments and their principal investigators is provided.

Urban, E. W.↗
DOE OSTI2021

Designs and Modeling of Architect Multi-material Scintillator System

We present a new conceptual radiation detector, the Architected Multimaterial Scintillator System, that utilizes a scintillator composed of multiple materials arranged in architected structures to enable new capabilities. By structuring differently-dyed materials, the wavelength of the scintillation light encodes additional information in radiation measurements. These structures can be realized through additive manufacture (3D-printing). Two classes of this concept are described and modelled using Monte Carlo simulations to evaluate their performance. The first detector design uses dye microstructures to encode particle tracking information, allowing for directional neutron detection and gamma/neutron discrimination. The second design uses a dye gradient to indicate the position of radiation along the gradient. The simulation results indicate this new concept in radiation detection can achieve strong performance in a variety of capabilities including particle identification, directionality and spectroscopy measurements, and particle position reconstruction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

The Design of an Ultra-Low Background Thermosyphon for the Majorana Demonstrator

The MAJORANA DEMONSTRATOR (MJD) is an ultra-low background neutrinoless double-beta decay (0νββ) experiment that will deploy up to 40 kg of high purity germanium detectors (HPGe). The goal of this experiment is to demonstrate the feasibility of building a detector array with less than 1 event/ton-year in a 4 keV region of interest around the 0νββ signal. HPGe diodes, when used as ionizing radiation detectors, need to be maintained at a temperature close to that of liquid nitrogen (77 K). This work describes the R&D results of a cryogenic system capable of meeting the requirements of low background and the cooling capacity required to successfully operate such a detector system. The MJD germanium detector modules will operate at liquid nitrogen temperature to provide adequate cooling for a full range of HPGe impurity concentrations. This paper shows the experimental results obtained using a two-phase horizontal thermosyphon using liquid nitrogen as the MJD’s cooling system. The cold test shows that the proposed thermosyphon has sufficient cooling power to handle the heat load of an MJD module. Results for the temperature gradient across the thermosyphon, cooling capacity, and design considerations demonstrate that the thermosyphon can effectively remove the calculated heat load of each module of the experiment. The thermosyphon will be bolted to a cold plate from which detector strings will hang. The thermal conductivity of a mockup of the MJD bolted thermal joint is experimentally determined to be below 0.1 K/W.

Detector arrays↗
DOE OSTI2016

Radioactive source localization in urban environments with sensor networks and the Internet of Things

The use of radiation detectors as an element in the so-called “Internet of Things” has recently become viable with the available of low-cost, mobile radiation sensors capable of streaming geo-referenced data. New methods for fusing the data from multiple sensors on such a network is presented. The traditional simple and ordinary Kriging methods present a challenge for such a network since the assumption of a constant mean is not valid in this application. In conclusion, a variety of Kalman filters are introduced in an attempt to solve the problem associated with this variable and unknown mean. Results are presented on a deployed sensor network.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Time Resolved Phonon Spectroscopy, Version 1.0

TRPS code was developed for the project "Time Resolved Phonon Spectroscopy". Routines contained in this piece of software were specially created to model phonon generation and tracking within materials that interact with ionizing radiation, particularly applicable to the modeling of cryogenic radiation detectors for dark matter and neutrino research. These routines were created to link seamlessly with the open source Geant4 framework for the modeling of radiation transport in matter, with the explicit intent of open sourcing them for eventual integration into that code base.

Goett, Johnny↗