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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Thick target neutron yields from Beryllium, Carbon, Tungsten, and Lead targets irradiated by 26.7 MeV/nucleon 4 H e ions

The angular and energy distributions of secondary neutrons produced from 26.7 MeV/nucleon 4 He ions, stopping in thick Be, C, W and Pb targets are measured by the time of flight method. The GEANT4, PHITS, and FLUKA Monte Carlo simulation codes with different physics models are employed to simulate the neutron yields and the results are compared with the experimental data. For the thick Be and C targets, GEANT4 with INCL++ reproduces the experimental data reasonably well. Whereas PHITS with JQMD-2.0 overestimates the neutron yields at intermediate energies and FLUKA with PEANUT underestimated the neutron yields at intermediate energies. For W and Pb targets, FLUKA with PEANUT physics model agree with experimental data best. PHITS with JQMD-2.0 overestimates the neutron yield at intermediate energies at 0°, and GEANT4 with INCL++ underestimates the neutron yield at intermediate energies at three angles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

The effect of image-guided radiation therapy on the margin between the clinical target volume and planning target volume in lung cancer

Introduction: This study aimed to evaluate the effect of image-guided radiation therapy (IGRT) on the margin between the clinical target volume (CTV) and planning target volume (PTV) in lung cancer. Methods: The CTV and PTV margin were determined in three dimensions by four radiation oncologists using a standard method in 10 lung cancer patients, and compared to consensus values. Transfer error was measured using a rigid phantom containing gold markers. Systematic error and random error set up errors were calculated in three dimensions from pre-treatment and post-treatment cone beam CT scans. Finally, the margin between the CTV and PTV was corrected for set up error and calculated. Results: The margins between the CTV and PTV with IGRT (and without IGRT) were 0.88 cm (0.96 cm), 0.99 cm (1.08 cm) and 1.28 cm (1.82 cm) in the anterior and posterior (AP), left and right (LR) and superior and inferior (SI) directions, respectively. Images from two other patients verified the validity of the corrected margin. The target delineation errors of the radiation oncologists are considered to be the largest compared with the set up errors. The application of IGRT reduced the set up errors and the margins between CTV and PTV. Conclusions: The delineation errors of radiation oncologists are the most important factor to consider for the margin between CTV and PTV for lung cancer. IGRT can reduce the margins by reducing the set up errors, especially in the SI direction. Further research is required to assess whether the reduction in the margin is solely based on set up errors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Alginate–peptide amphiphile core–shell microparticles as a targeted drug delivery system

We describe in this work the synthesis of microparticles with a doxorubicin drug conjugated alginate core and a shell of peptide amphiphile nanofibres functionalized for targeting the folate receptor. The spherical geometry of the particle core allows high drug loading per surface area, whereas the nanoscale fibrous shell formed by self-assembly of peptide amphiphiles offers a high surface to volume ratio that is ideal for targeting. Furthermore, the synthesised microparticles have a 60-fold higher cytotoxicity against MDA-MB-231 breast cancer cells compared to non-targeting particles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Target and beam-target spin asymmetries in exclusive pion electroproduction for Q 2 > 1 GeV 2 . I. e p → e π + n

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π+ electroproduction reaction γ*p → nπ + . The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is 1.1 < W < 3 GeV and 1 < Q 2 < 6GeV 2 . Results were obtained for about 6000 bins in W, Q 2 , cos(θ*), and Φ*. Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W. Finally, a generalized parton distributions (GPD)-based model is in poor agreement with the data. When combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q 2 , for resonances with masses as high as 2.4 GeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Target and beam-target spin asymmetries in exclusive pion electroproduction for Q 2 > 1 GeV 2 . II. e p → e π 0 p

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π + electroproduction reaction γ*p→nπ + . The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is 1.1 < W < 3 GeV and 1 < Q 2 < 6GeV 2 . Results were obtained for about 6000 bins in W, Q 2 , cos(θ*), and Φ*. Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W. A generalized parton distributions (GPD)-based model is in poor agreement with the data. As a result, when combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q 2 , for resonances with masses as high as 2.4 GeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Hyperspectral target detection using manifold learning and multiple target spectra

Imagery collected from satellites and airborne platforms provides an important tool for remotely analyzing the content of a scene. In particular, the ability to remotely detect a specific material within a scene is of critical importance in nonproliferation and other applications. The sensor systems that process hyperspectral images collect the high-dimensional spectral information necessary to perform these detection analyses. For a d-dimensional hyperspectral image, however, where d is the number of spectral bands, it is common for the data to inherently occupy an m-dimensional space with m << d. In the remote sensing community, this has led to recent interest in the use of manifold learning, which seeks to characterize the embedded lower-dimensional, nonlinear manifold that the data discretely approximate. The research presented in this paper focuses on a graph theory and manifold learning approach to target detection, using an adaptive version of locally linear embedding that is biased to separate target pixels from background pixels. Finally, this approach incorporates multiple target signatures for a particular material, accounting for the spectral variability that is often present within a solid material of interest.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2012

Effect of target-substrate distance on properties of flexible InZnSnO films grown by linear facing target sputtering

The authors have investigated the effect of target-to-substrate distance (TSD) on the electrical, optical, and structural properties of flexible InZnSnO (IZTO) films grown on polyethylene terephthalate substrates using linear facing target sputtering (LFTS) at room temperature. The electrical and optical properties of IZTO film grown by LFTS were significantly influenced by TSD while the structural and surface properties of IZTO film were not affected by TSD, unlike conventional magnetron sputtering. Regardless of TSD, all IZTO film showed completely amorphous structure with very low root mean square roughness of 0.33 nm, due to the low kinetic energy of sputtered IZTO atoms and a substrate position that did not directly face the targets. Based on the figure of merit value, the optimized TSD for deposition of flexible IZTO films is 2.5 cm. At optimized conditions, the IZTO film showed a sheet resistance of 23.1 {Omega}/sq and an optical transmittance of 80%.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Crystal Structure of a CRISPR RNA-guided Surveillance Complex Bound to a ssDNA Target

In prokaryotes, RNA derived from type I and type III CRISPR loci direct large ribonucleoprotein complexes to destroy invading bacteriophage and plasmids. In Escherichia coli, this 405-kilodalton complex is called Cascade. We report the crystal structure of Cascade bound to a single-stranded DNA (ssDNA) target at a resolution of 3.03 angstroms. The structure reveals that the CRISPR RNA and target strands do not form a double helix but instead adopt an underwound ribbon-like structure. This noncanonical structure is facilitated by rotation of every sixth nucleotide out of the RNA-DNA hybrid and is stabilized by the highly interlocked organization of protein subunits. These studies provide insight into both the assembly and the activity of this complex and suggest a mechanism to enforce fidelity of target binding.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Target fabrication fields first NIF shot with new 3D-printed microfluidic target design

Capable of producing ultrafine features, two-photon polymerization (2PP) 3D printing made it possible to field a first-of-its-kind leak-proof liquid-filled diffraction target. These targets are used for shots aimed at using laser pressure instead of low temperatures turn water into ice. The shot is the product of months of design, assembly, and installation work by LSEO’s target fabrication team, in collaboration with 3D printing experts Widi Moestopo (MED) and Xiaoxing Xia (MED) and PLS researcher Neal Bhandarkar.

42 ENGINEERING↗
DOE OSTI2023

Methodology to Generate the Decay Gamma Source for a Second Target Station Target Wedge

This report details the specifics of applying the Position-Averaged Method methodology for the calculation of the rotating lasagna-style target wedge activation and the resulting decay gamma source terms. The methodology uses MCNP® Code Version 6.2.0 with the RNUCS patch coupled with CINDER2008 from the AARE V1.0 package. The process begins with model preparations that include ensuring impurities are included in the materials in the regions of interest along with segmentation of the geometry in order to capture the decay gamma source gradients. This report also details the physics models and other MCNP®, CINDER2008, and ADVANTG 3.2.0 related options used to calculate the decay gamma source terms. ADVANTG 3.2.0 is used to generate a weight window set to aid in convergence of the neutron fluxes in the initial MCNP® protons-on-target particle transport calculation to calculate the neutron fluxes and spallation products in the regions of interest. The neutron fluxes and spallation products are then used in the CINDER2008 transmutation calculation, and the decay gamma sources are generated by the AARE_GAMMA_SOURCE_SCRIPT as a part of the AARE V1.0 package. These decay gamma sources include the energy distributions as well as the necessary distributions to sample the location of the source using the cell rejection method. The gamma sources that are produced using the methodology may be used for a wide variety of analysis involving the target wedge. This report includes the material specifications, physics options, proton source term description, geometrical configuration, and post-processing details.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Targets and methods for target preparation for radionuclide production

The invention relates to nuclear technology, and to irradiation targets and their preparation. One embodiment of the present invention includes a method for preparation of a target containing intermetallic composition of antimony Ti--Sb, Al--Sb, Cu--Sb, or Ni--Sb in order to produce radionuclides (e.g., tin-117 m) with a beam of accelerated particles. The intermetallic compounds of antimony can be welded by means of diffusion welding to a copper backing cooled during irradiation on the beam of accelerated particles. Another target can be encapsulated into a shell made of metallic niobium, stainless steel, nickel or titanium cooled outside by water during irradiation. Titanium shell can be plated outside by nickel to avoid interaction with the cooling water.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Ultra-thin targets or target-backings for accelerator

A procedure has been developed for fabrication of ultra-thin titanium foils for accelerator-based experiments. Evaporation of thin titanium layers on thin copper foils allows mechanical manipulation of the layered-foil prior to dissolution of the copper layer which leaves the thin titanium foil attached to a target frame. This is the rst time that thin titanium foils have been produced in this manner. Electrodeposition techniques can be used to result in radioactive deposits being placed ultimately on an ultra-thin titanium backing. This method was used in the past for thin nickel foils, but has been "lost" due to the companies that used to manufacture such foils not being in business any more, removing the source of copper backed foils from the market. The technique can be used for thin nickel or chromium foils, as well as several other types of foils. Titanium foils as thin as 100 nm (45 μg/cm 2 ), nickel foils as thin as 50 nm (45 μg/cm 2 ), and chromium foils as thin as 400 nm (290 μg/cm 2 ) have been successfully attached to stainless steel target frames.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Study of Rayleigh–Taylor growth in directly driven cryogenic-deuterium targets

Direct-drive, Rayleigh–Taylor growth experiments in liquid deuterium (D2) were performed on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar cryogenic targets at a laser intensity of ∼4 × 1014 W/cm2. These are the first Rayleigh–Taylor measurements in deuterium at conditions relevant to inertial confinement fusion using a mass preimposed initial modulation. The measured modulation optical depths are in agreement with the 2D hydrodynamics code DRACO using flux-limited local thermal transport, providing an important step in the experimental validation of simulations for direct-drive ignition.

Hager, J. D.↗
DOE OSTI2015

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κ{sub QMD}), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ∼2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Polar-direct-drive experiments with contoured-shell targets on OMEGA

Polar-driven direct-drive experiments recently performed on the OMEGA Laser System have demonstrated the efficacy of using a target with a contoured shell with varying thickness to improve the symmetry and fusion performance of the implosion. The polar-driven contoured-shell implosions have substantially reduced low mode perturbations compared to polar-driven spherical-shell implosions as diagnosed by x-ray radiographs up to shell stagnation. As a result, fusion yields were increased by more than a factor of ~2 without increasing the energy of the laser by the use of contoured shells.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗