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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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We illustrate inherent differences between Single Event Transients generated by an above bandgap picosecond lasers and MeV heavy ions by comparing transient currents collected with an ion microbeam and picosecond laser with varying track waist.
Astronauts are exposed to galactic cosmic rays (GCR), trapped protons, and possible solar particle events (SPE) during spaceflight. For such complicated mixtures of radiation types and kinetic energies, tissue equivalent proportional counters (TEPC's) represent a simple time-dependent approach for radiation monitoring. Of interest in radiation protection is the average quality factor of a radiation field defined as a function of linear energy transfer, LET, Q(sub ave)(LET). However TEPC's measure the average quality factors as a function of lineal energy (y), Q(sub ave)(y) defined as the average energy deposition in a volume divided by the average chord length of the volume. Lineal energy, y deviates from LET due to energy straggling, delta-ray escape or entry, and nuclear fragments produced in the detector. Using integrated space radiation models that includes the transport code HZETRN/BRYNTRN, the quantum nuclear interaction model, QMSFRG, and results from Monte-Carlo track simulations of TEPC's response to ions, we consider comparisons of model calculations to TEPC results from NASA missions in low Earth orbit and make predictions for lunar and Mars missions. Good agreement between the model and measured spectra from past NASA missions is found. A finding of this work is that TEPC's values for trapped or solar protons of Q(sub ave)(y) range from 1.9-2.5, overestimating Q(sub ave)(LET), which ranges from 1.4-1.6 with both quantities increasing with shielding depth due to nuclear secondaries Comparisons for the complete GCR spectra show that Q(sub ave)(LET) for GCR is approximately 3.5-4.5, while TEPC's measure 2.9-3.4 for Q(sub ave)(y) with the GCR values decreasing with depth as heavy ions are absorbed in shielding material. Our results support the use of TEPC's for space radiation environmental monitoring when computational analysis is used for proper data interpretation.
Both solar wind charge exchange emission and diffuse thermal emission from the Local Bubble are strongly dominated in the soft X-ray band by lines from highly ionized elements. While both processes share many of the same lines, the spectra should differ significantly due to the different production mechanisms, abundances, and ionization states. Despite their distinct spectral signatures, current and past observatories have lacked the spectral resolution to adequately distinguish between the two sources. High-resolution X-ray spectroscopy instrumentation proposed for future missions has the potential to answer fundamental questions such as whether there is any hot plasma in the Local Hot Bubble, and if so, what are the abundances of the emitting plasma and whether the plasma is in equilibrium. Such instrumentation will provide dynamic information about the solar wind including data on ion species which are currently difficult to track. It will also make possible remote sensing of the solar wind.
The Deep Space Atomic Clock mission is developing a small, mercury ion atomic clock with Allan deviation of less than 1e-14 at one day (current estimates < 3e-15) for a yearlong space demonstration beginning late- 2016/early-2017. DSAC’s stability yields one-way radiometric data precision on par with current two-way data. Uplink one-way tracking with an appropriately configured radio enables the possibility of onboard, autonomous radio navigation. This study examines the modeling needed to efficiently process this data for an onboard implementation.
Abstract Organic mixed ionic‐electronic conductors (OMIECs) have emerged as promising materials for a wide range of next‐generation technologies, including bioelectronics and neuromorphic computing. The performance of these materials depends on the transport of ions through the polycrystalline polymer matrix as well as how the distribution of ions and polarons in crystalline and amorphous regions impacts electronic transport. However, it is often challenging to distinguish whether ions enter crystalline or amorphous regions. In this work, steady‐state and time‐resolved photoluminescence (PL) spectroelectrochemistry is used to probe initial ion insertion in crystalline and amorphous regions of the OMIEC material poly(3‐[2‐[2‐(2‐methoxyethoxy)ethoxy]ethyl]thiophene ‐2,5‐diyl) (P3MEEET) as a function of applied voltage. It is found that PL spectroelectrochemistry reports on the initial stages of electrochemical doping through the quenching of PL emission. By distinguishing between amorphous and crystalline contributions to the PL spectrum, ion insertion in crystalline and amorphous regions as a function of voltage is tracked. It is found that PL spectroelectrochemistry is much more sensitive to the initial injection of ions than complementary methods, highlighting its potential as a sensitive tool for interrogating ion injection in OMIECs.
Directly observing the evolution of material performance in-situ under extreme conditions remains a great challenge. Emergent behavior, such as the transition from incubation to steady state void swelling, is often difficult to capture in these conditions. To fill this gap, transient grating spectroscopy (TGS) has been used to collect multi-property information in-situ under high temperature exposure to ion beam irradiation. This all-optical method returns elastic and thermal transport properties with second-scale time resolution. Here, recent work using this methodology to track the evolution of Ni-based solid-solution alloys using the in situ ion irradiation TGS (I3TGS) beamline will be described. Tracking material property evolution during long exposure times (hours) provides a clear indication of when void swelling has occurred. On short timescales (seconds to minutes), observing rapid changes in thermoelastic properties as defect generation is initiated allows a unique window into bulk transient defect populations which are otherwise difficult to observe.
Abstract sPHENIX is a high energy nuclear physics experiment under construction at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory (BNL). The primary physics goals of sPHENIX are to study the quark-gluon-plasma, as well as the partonic structure of protons and nuclei, by measuring jets, their substructure, and heavy flavor hadrons in $$p$$ p $$+$$ + $$p$$ p , p + Au, and Au + Au collisions. sPHENIX will collect approximately 300 PB of data over three run periods, to be analyzed using available computing resources at BNL; thus, performing track reconstruction in a timely manner is a challenge due to the high occupancy of heavy ion collision events. The sPHENIX experiment has recently implemented the A Common Tracking Software (ACTS) track reconstruction toolkit with the goal of reconstructing tracks with high efficiency and within a computational budget of 5 s per minimum bias event. This paper reports the performance status of ACTS as the default track fitting tool within sPHENIX, including discussion of the first implementation of a time projection chamber geometry within ACTS.
We will present what we believe to be the first reported observations of up- and downflows of topside ionospheric thermal plasmas from multiple near-simultaneous tracks through the high-latitude topside ionosphere. From several Southern polar passes, it has been possible to construct plots of field-aligned flows of 0+ observed by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft near 5000 km altitude together with vertical ion flow observations from one or more DMSP spacecraft near 800 km altitude. These observations provide a glimpse of the wide-spread upward and downward ionospheric ion flows over the broad polar region along multiple distinct satellite tracks. For the instances where DMSP and POLAR cross nearly the same field lines at the 800 and 5000 kin altitudes, we will show ion parameter measurements at these to altitudes in comparison to Dynamic Fluid-Kinetic(DyFK) transport simulations of anticipated altitude profiles of these parameters.
All mineral detectors exposed on Apollo 16 had high surface track densities probably produced by a solar flare that occurred during the mission. The heavy ions followed a power law spectrum with exponent approximately 3 down to approximately 200 KeV/nucleon. The abundance of low-energy particle tracks observed in this flare may explain the high track densities observed in lunar dust grains. Pristine heavy-particle tracks in feldspar give long tracks. Shallow pits similar to those expected from extremely heavy solar wind ions were observed in about the expected number. Initial results give a low apparent value of neutron albedo relative to theory.
IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays.
In January 1990, the Long Duration Exposure Facility (LDEF) spacecraft was retrieved after nearly 6 years in space in a 28.4 deg orbit at a mean altitude of 476 km. Onboard LDEF was NRL's Heavy Ions In Space (HIIS) experiment, comprising large thick stacks of plastic track detectors with a total collecting power of 2.0 sq m-sr. We report preliminary results on the observation of stopping Fe-group ions at energies far below the geomagnetic cutoff for fully-ionized galactic cosmic rays.
In early-type X-ray binaries, the recombination time scales for ions such as C IV, Si IV, and N V in the stellar winds of their massive OB companion stars can be very short compared to typical X-ray pulsation or fluctuation time scales. Thus, the authors predict that the 'bleached zones', in which these ions are removed from the stellar wind by X-ray photoionization, will track the X-ray beam as it rotates and that the P Cygni line profiles due to these ions will pulsate. With the IUE satellite the authors obtained low-resolution UV spectra of the binary X-ray system HD 77581/4U 0900-40 resolved into six phase bins of the 283 s pulse period; the observed upper limit to the pulse amplitude of the equivalent width of C IV 1550 A was less than the predicted value. However, the pulsations should be easy to observe with the Hubble Space Telescope.
The biological response to high-LET radiation is very different from low-LET radiation, and can be partly attributed to the energy deposition by the radiation. Several experiments, notably detection of gamma-H2AX foci by immunofluorescence, has revealed important differences in the nature and in the spatial distribution of double-strand breaks (DSB) induced by low- and high-LET radiations. Many calculations, most of which are based on amorphous track models with radial dose, have been combined with chromosome models to calculate the number and distribution of DSB within nuclei and chromosome aberrations. In this work, the Monte-Carlo track structure simulation code RITRACKS have been used to calculate directly the energy deposition in voxels (3D pixels). A cubic volume of 5 micrometers of side was irradiated by 1) 450 (1)H+ ions of 300 MeV (LET is approximately 0.3 keV/micrometer) and 2) by 1 (56)Fe26+ ion of 1 GeV/amu (LET is approximately 150 keV/micrometer). In both cases, the dose deposited in the volume is approximately 1 Gy. All energy deposition events are recorded and dose is calculated in voxels of 20 micrometers of side. The voxels are then visualized in 3D by using a color scale to represent the intensity of the dose in a voxel. This simple approach has revealed several important points which may help understand experimental observations. In both simulations, voxels which receive low dose are the most numerous, and those corresponding to electron track ends received a dose which is in the higher range. The dose voxels are distributed randomly and scattered uniformly within the volume irradiated by low-LET radiation. The distribution of the voxels shows major differences for the (56)Fe26+ ion. The track structure can still be seen, and voxels with much higher dose are found in the region corresponding to the track "core". These high-dose voxels are not found in the low-LET irradiation simulation and may be responsible for DSB that are more difficult to repair. By applying a threshold on the dose visualization, voxels corresponding to electron track ends are evidenced and the spatial distribution of voxels is very similar to the distribution of DSB observed in gamma H2AX experiments, even if no chromosomes have been included in the simulation. Furthermore, this work has shown that a significant dose is deposited in voxels corresponding to electron track ends. Since some delta-rays from iron ion can travel several millimeters, they may also be of radiobiological importance.
The high-charge high-energy (HZE) ion components of the galactic cosmic rays when compared to terrestrial forms of radiations present unique challenges to biological systems. In this paper we present a deoxyribonucleic acid (DNA) breakage model to visualize and analyze the impact of chromatin domains and DNA loops on clustering of DNA damage from X rays, protons, and HZE ions. Our model of DNA breakage is based on a stochastic process of DNA double-strand break (DSB) formulation that includes the amorphous model of the radiation track and a polymer model of DNA packed in the cell nucleus. Our model is a Monte-Carlo simulation based on a randomly located DSB cluster formulation that accomodates both high- and low-linear energy transfer radiations. We demonstrate that HZE ions have a strong impact on DSB clustering, both along the chromosome length and in the nucleus volume. The effects of chromosomal domains and DNA loops on the DSB fragment-size distribution and the spatial distribution of DSB in the nucleus were studied. We compare our model predictions with the spatial distribution of DSB obtained from experiments. The implications of our model predictions for radiation protection are discussed.
Abstract Environmental and host-associated microbiomes are typically diverse assemblages of organisms performing myriad activities and engaging in a network of interactions that play out in spatially structured contexts. As the sum of these activities and interactions give rise to overall microbiome function, with important consequences for environmental processes and human health, elucidating specific microbial activities within complex communities is a pressing challenge. Single-cell stable isotope probing (SC-SIP) encompasses multiple techniques that typically utilize Raman microspectroscopy or nanoscale secondary ion mass spectrometry (NanoSIMS) to enable spatially resolved tracking of isotope tracers in cells, cellular components, and metabolites. SC-SIP techniques are uniquely suited for illuminating single-cell activities in microbial communities and for testing hypotheses about cellular functions generated for example from meta-omics datasets. Here, we illustrate the insights enabled by SC-SIP techniques by reviewing selected applications in microbiology and offer a perspective on their potential for future research.
The advantage of the multicolor banding in situ hybridization (mBAND) technique is its ability to identify both inter- (translocation to unpainted chromosomes) and intra- (inversions and deletions within a single painted chromosome) chromosome aberrations simultaneously. To study the detailed rearrangement of low- and high-LET radiation induced chromosome aberrations in human epithelial cells (CH184B5F5/M10) in vitro, we performed a series of experiments with Cs-137 gamma rays of both low and high dose rates, neutrons of low dose rate and 600 MeV/u Fe ions of high dose rate, with chromosome 3 painted with multi-binding colors. We also compared the chromosome aberrations in both 2- and 3-dimensional cell cultures. Results of these experiments revealed the highest chromosome aberration frequencies after low dose rate neutron exposures. However, detailed analysis of the radiation induced inversions revealed that all three radiation types induced a low incidence of simple inversions. Most of the inversions in gamma-ray irradiated samples were accompanied by other types of intra-chromosomal aberrations but few inversions were accompanied by inter-chromosomal aberrations. In contrast, neutrons and Fe ions induced a significant fraction of inversions that involved complex rearrangements of both inter- and intrachromosomal exchanges. The location of the breaks involved in chromosome exchanges was analyzed along the painted chromosome. The breakpoint distribution was found to be randomly localized on chromosome 3 after neutron or Fe ion exposure, whereas non-random distribution with clustering breakpoints was observed after -ray exposure. Our comparison of chromosome aberration yields between 2- and 3-dimensional cell cultures indicated a significant difference for gamma exposures, but not for Fe ion exposures. These experimental results indicated that the track structure of the radiation and the cellular/chromosome structure can both affect radiation-induced chromosome aberrations.
Space weathering causes the surface soils of airless bodies like the Moon to be micro-structurally and chemically altered by exposure to micrometeoroid bombardment and solar wind irradiation. These alterations accumulate in surface grains with continued residence in the uppermost millimeters of regolith. Low energy solar wind ions (largely H+ and He+) produce a layer of radiation damage as they become implanted in grain surfaces. Also present are solar energetic particle (SEP) tracks, which are nanoscale lineations within grain interiors formed by heavy, high-energy ions (mainly Fe group nuclei) penetrating up to millimeters below the surface. Recent work has determined that the width of solar wind-damaged rims on anorthite and olivine, and their respective SEP track densities are correlated with each other and with grain surface exposure age. Core sample 73002, recently released under the Apollo Next Generation Sample Analysis (ANGSA) Program, has provided an opportunity to study material collected from the light mantle formation in the Taurus-Littrow Valley during Apollo 17. The light mantle is thought to have been deposited vial and slide originating from the neighboring South Massif. Spectral analysis of bulk core soils found a plagioclase rich composition, confirming a highlands origin of the formation. Spectral profiles and ferromagnetic resonance (FMR) measurements of bulk soils sampled at cm-intervals from 73002 indicate that regolith up to~9.5 cm in depth have maturity indices consistent with longer durations of surface processing than samples deeper in the core. Thus, this upper ~9 cm layer likely represents the maximum extent of an in-situ reworking zone which may have persisted over 5 to 17million years. Here we present an analysis of grain exposure ages within the in-situ reworking zone of 73002derived from SEP track density measurements via transmission electron microscopy.
A new C++ custom element has been developed with the framework of General Particle Tracer (GPT) to simulate electron impact ionization of residual gas molecules. The custom element uses Monte-Carlo routines to determine both the ion production rate and the secondary electron kinetic energy based on user-defined gas densities and theoretical values for the ionization cross section and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the newly formed ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations and against simulations made using the simulation package IBSimu. While the custom element was originally built for particle accelerator simulations, it is readily extensible to other applications. The custom element will be described in detail and examples of applications at the Thomas Jefferson National Accelerator Facility will be presented for ion production in a DC high voltage photo-gun.