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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Optical model calculations of heavy-ion target fragmentation

The fragmentation of target nuclei by relativistic protons and heavy ions is described within the context of a simple abrasion-ablation-final-state interaction model. Abrasion is described by a quantum mechanical formalism utilizing an optical model potential approximation. Nuclear charge distributions of the excited prefragments are calculated by both a hypergeometric distribution and a method based upon the zero-point oscillations of the giant dipole resonance. Excitation energies are estimated from the excess surface energy resulting from the abrasion process and the additional energy deposited by frictional spectator interactions of the abraded nucleons. The ablation probabilities are obtained from the EVA-3 computer program. Isotope production cross sections for the spallation of copper targets by relativistic protons and for the fragmenting of carbon targets by relativistic carbon, neon, and iron projectiles are calculated and compared with available experimental data.

Townsend, L. W.↗
DOE OSTI2017

Quantification of 85 Rb, 136 Ce, 142 Nd and 150 Nd Enriched Isotope Standards

Enriched isotope standards are required for routine nuclear fuel burnup and other radiochemical analyses. In 2017 Idaho National Laboratory (INL) generated isotope standard solutions containing enriched 85 Rb, 136 Ce, 142 Nd, and 150 Nd. Oxide and chloride forms of each enriched isotope were obtained from the Oak Ridge Isotope Production program, dissolved, and quantified by isotope dilution-multi collector mass spectrometry. Quantification of the isotope solutions was performed independently by two separate laboratories at INL: the Analytical Laboratory (AL) at the Material and Fuels Complex (MFC) and the Ultra-trace Analytical Laboratory (UAL) in Idaho Falls. Concentration measurement results for all solutions and 142 Nd isotope ratio values reported by both laboratories are in quantitative agreement with each other, while isotope ratio values reported for 150 Nd are observed to have an apparent ~0.8% bias between the results of each laboratory. Data for 85 Rb/ 87 Rb isotope ratio values for UAL TIMS measurements and AL MC-ICP-MS measurements are in quantitative agreement with each other, while those of UAL MC-ICP-MS are observed to be much higher due to the existence of unidentified polyatomic interferences in the 84-88 m/z range for this instrument. Concentration and isotope ratio values for these isotope tracer solutions, along with detailed description of the analytical and data analysis methods utilized, are reported herein.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

A nuclear physics program at the Rare Isotope Beams Accelerator Facility in Korea

This paper outlines the new physics possibilities that fall within the field of nuclear structure and astrophysics based on experiments with radioactive ion beams at the future Rare Isotope Beams Accelerator facility in Korea. This ambitious multi-beam facility has both an Isotope Separation On Line (ISOL) and fragmentation capability to produce rare isotopes beams (RIBs) and will be capable of producing and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. The large dynamic range of reaccelerated RIBs will allow the optimization in each nuclear reaction case with respect to cross section and channel opening. The low energy RIBs around Coulomb barrier offer nuclear reactions such as elastic resonance scatterings, one or two particle transfers, Coulomb multiple-excitations, fusion-evaporations, and direct capture reactions for the study of the very neutron-rich and proton-rich nuclides. In contrast, the high energy RIBs produced by in-flight fragmentation with reaccelerated ions from the ISOL enable to explore the study of neutron drip lines in intermediate mass regions. The proposed studies aim at investigating the exotic nuclei near and beyond the nucleon drip lines, and to explore how nuclear many-body systems change in such extreme regions by addressing the following topics: the evolution of shell structure in areas of extreme proton to neutron imbalance; the study of the weak interaction in exotic decay schemes such as beta-delayed two-neutron or two-proton emission; the change of isospin symmetry in isobaric mirror nuclei at the drip lines; two protons or two neutrons radioactivity beyond the drip lines; the role of the continuum states including resonant states above the particle-decay threshold in exotic nuclei; and the effects of nuclear reaction rates triggered by the unbound proton-rich nuclei on nuclear astrophysical processes.

43 PARTICLE ACCELERATORS↗
NASA NTRS2004

Winds, Water Budgets and Stable Isotopes in Tropical Cyclones using TRMM and QUICKSCAT

Water vapor is the most abundant greenhouse gas in the atmosphere. Changes in its concentration and distribution are controlled by the hydrologic cycle. Because of its capacity to absorb and emit long wave radiation, release latent heat during condensation in storms and reflect short wave radiation when clouds form it has a major impact on Global climate change. The stable isotope ratios of water are H20 H2l6O and H0 H2l6O. These ratios change whenever water undergoes a phase change. They also change in both rain and water vapor whenever an air parcel is exposed to rain. In addition the relative changes in the two ratios differ as a &nction of the relative humidity. In short, the stable isotope ratios in water vapor in the atmosphere contain an integrated history of the processes affecting the concentration and distribution of water vapor in the atmosphere. Therefore the measurement and interpretation of changes in these stable isotope ratios are a powerful tool matched by no other method in tracing the transport history of water in the atmosphere. Our initial studies under this grant focused on the changes of the stable isotope ratios of precipitation and water vapor in tropical cyclones. The changes in time and space were found to be very large and to trace the transport of water in the storms reflecting changes in basic structural features. Because the stable isotope ratios of rains from tropical cyclones are so low flooding associated with land falling tropical cyclones introduces a negative isotopic spike into the coastal surface waters. In addition the stable isotope ratios of water vapor in the vicinity of tropical cyclones is anomalously low. This suggests that carbonate shelled organisms such as ostracoda living in coastal waters have the potential to record the isotopic spike and thereby provide a long term record of tropical storm activity in sediment cores containing fossil shells. Likewise, tree rings in coastal environments offer a similar potential. We have analyzed the oxygen isotopic composition of ostrcoda shells formed in the floodwaters of Tropical Storm Allison (2001) and discovered the negative isotopic 1 16 spike. Because we had learned that storm activity has a major impact on the stable isotope ratios of water vapor in the tropics and sub-tropics we decided to analyze the isotopic compositions of water vapor in different locations in the tropics. We did this in Puerto Escondido, Mexico in July 1998, near Kwajalein Island in the Pacific in 1999 as part of a TRMM summer field program and in 2001 in Key West, Florida as part of the CAMEX 4 summer field program. Our isotopic studies along with our earlier tropical cyclone studies showed that the low isotopic ratios in water vapor induced by exposure to rains the storms persisted for 48 hours often far away from the original storm site. We also noted that positive isotopic spikes were introduced into atmospheric water vapor if winds were high and extensive sea spray was present. These findings have a significant impact on the interpretation of the stable isotope studies of tropical ice cores found in the high mountain regions of the tropics. The assumption made in interpreting the ice core record is that the source water vapor evaporated from the sea surface is in near isotopic equilibrium with the seawater and undergoes a decrease during its transport that reflects the change in temperature from the sea surface to the site of the ice core. Because an additional isotopic depletion occurs at the sea surface source area that depends on the intensity, duration and size of the tropical rain system the isotopic variations found in the ice cores must take into account changes in past storm activity in the tropics. These systems must be an important source of water vapor to the ice cores because they charge the troposphere with water vapor to a far greater vertical height than evaporation in quiescent regions. Finally, an interest in increased heat transfer in thnterior of tropical cyclones resulting from greater amounts of sea spray is a topic of considerable interest to the research community. Increases in sea spray may be related to rapid changes in the intensity of hurricanes, a feature of hurricanes that currently is very poorly forecast. Project CBLAST of the Hurricane Research Division of NOAA is an active program that uses P3 research aircraft to evaluate this problem. An instrument has been designed and built at the University of Houston that will be placed on the P3 research aircraft during the 2004 hurricane season. It continuously measures the salt content of rain in hurricanes. Changes in the salt content of the rains should reflect the abundance of sea spray at the sea surface. In this way maps of sea spray intensity in hurricanes may be forthcoming. This should help computer modelers who simulate hurricanes to better understand the potential of changes in sea spray to change the intensity of hurricanes. The cost of designing, building and installing this instrument was borne largely by funding from this NASA grant. A list of presentations at national meetings and publications that were as the result of funding from this NASA grant are found in the report.

Lawrence, James R.↗
DOE OSTI2020

Facile Decomposition of Organophosphonates by Dual Lewis Sites on a Fe 3 O 4 (111) Film

Dimethyl methylphosphonate (DMMP) is used as a simulant for toxic nerve agents and pesticides, rendering the understanding of surface chemistry requisite to design effective materials for organophosphonate (catalytic) decomposition at room temperature. In this work, DMMP surface chemistry is studied on an iron oxide surface in a very well-defined environment using temperature-programmed reaction, isotopic labeling, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory. DMMP, (CH 3 O) 2 P(O)(CH 3 ), dissociates to yield methoxy and methyl methylphosphonate, (CH 3 O)P(O) 2 (CH 3 ), on the surface at room temperature. At higher temperatures, dimethyl ether is formed via intramolecular reaction, followed by the formation of formaldehyde and methanol from adsorbed methoxy decomposition during temperature-programmed reaction. Ultimately, stochiometric combustion at 870 K produces CO, H 2 C=O, and CO 2 via reaction with lattice oxygen, with PO x remaining on the surface. Excess oxygen from the bulk is required to drive these higher temperature pathways. Neither hydrolysis nor a photoreaction is observed, when exposing the adsorbed DMMP to water or light above the band gap, respectively. No evolution of P-containing species is detected, indicating efficient trapping of this contaminant. The activity for DMMP decomposition at room temperature is reduced by the accumulation of PO x . However, a significant amount of reaction persists after multiple temperature-programmed reaction experiments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

MatMCNP: A Code for Producing Material Cards for MCNP

A code for generating MCNP material cards (MatMCNP) has been written and verified for naturally occurring, stable isotopes. The program allows for material specification as either atomic or weight percent (fractions). MatMCNP also permits the specification of enriched lithium, boron, and/or uranium. In addition to producing the material cards for MCNP, the code calculates the atomic (or number) density in atoms/barn-cm as well as the multiplier that should be used to convert neutron and gamma fluences into dose in the material specified.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Development and Deployment of Retrofit PolarisQ Ion Trap Mass Spectrometer for Isotope Ratio Measurements

This report describes Oak Ridge National Laboratory’s (ORNL) FY15 progress in support of National Nuclear Security Administration’s (NNSA) Portable Mass Spectrometer project. A retrofit PolarisQ ion trap mass spectrometer (RPMS) has been assembled from components of two PolarisQ ion trap mass spectrometers used in previous isotope ratio programs. The retrofit mass spectrometer includes a custom Hastelloy vacuum chamber which is about ¼ the size of the standard aluminum vacuum chamber and reduces the instrument weight from the original by nine pounds. In addition, the new vacuum chamber can be independently heated to reduce impurities such as water, which reacts with UF 6 to produce HF in the vacuum chamber. The analyzer and all components requiring service are mounted on the chamber lid, facilitating quick and easy replacement of consumable components such as the filament and electron multiplier.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Procurement of 100 kg of Enriched Xenon for the EXO Prototype and for its Installation at WIPP

This grant supported the enriched xenon procurement, detector construction and initial operation of the EXO-200 double beta decay experiment at the Waste Isolation Pilot Plant (WIPP). The period of performance was Aug 15, 2002 to Dec 31, 2014. The primary goal of the experiment is to search for the very rare (and to date not observed) neutrino-less double beta decay. Such decay, if observed, would shed the light of the quantum-mechanical structure of neutrinos, and the origins of elementary particle masses. Another goal of the detector is to serve as prototype of a larger neutrino-less double beta decay experiment, currently being considered by DOE-OS. EXO-200 has already been extremely successful in both areas and is, in fact, leading the way world-wide in this area of fundamental physics. In the initial part of the grant the EXO-200 collaboration acquired 200kg of xenon enriched to 80% in the isotope 136 that is a candidate for double beta decay. At the time this was the largest isotope separation program carried out for fundamental science. The enrichment was done in Russia, providing a rare and valuable opportunity for US scientists to work alongside Russian colleagues, in some cases from the former closed cities of their military complex. By now the EXO-200 collaboration include institutions from the US, Canada, South Korea, China, Germany, Switzerland and Russia. Many collaborating scientists from these countries have taken shifts at WIPP or at the various remote monitoring sites world-wide. EXO-200 detector construction was completed in early 2010, with the time projection chamber (TPC) installation in the cleanrooms already placed in NeXA. Detector commissioning at WIPP followed, with the last phase, the filling of the TPC with liquid Xenon, occurring in the spring 2011. EXO-200 is described in [1]. Low background data taking started on Jun 1, 2011 and within the first month of data the 2-neutrino double beta decay of 136Xe was discovered, as reported in [2]. More data provided the best half-life measurement of any 2-neutrino double-beta decay modes [3]. Until Feb 2014 the detector ran continuously producing some of the world leading results in the field and, in particular, two of the most sensitive searches for neutrinoless double beta decay [4,5]. These measurements show that the half life of this decay is longer than 1015 times the age of the universe. This is one of the leading results in this field world-wide and succeeded to put the DOE-funded research on the world stage in a very cost-effective way. Other results from EXO-200 include a search for exotic double-beta decay modes [6], a detailed report on the state of the art background levels achieved in the detector [7], the study of rare ion and neutral atom motion and neutralization rates in liquid Xenon [8], a study of the cosmogenic backgrounds in the detector at WIPP’s depth [9], a search for Lorentz and CPT symmetries violation [10] and a search for double-beta decay to excited states [11]. In Feb 2014 the EXO-200 detector was severely disrupted by the accidents in the WIPP underground (unrelated to EXO-200). The EXO-200 operations team was able to recover the unique stockpile of enriched Xenon to high pressure cylinders and warm-up the detector to room temperature without damaging the very delicate equipment. This was a very impressive achievement as no plan had been made to complete these operations entirely from remote. This validates the robustness of well-designed liquid xenon detectors for this and other measurements in particle and nuclear astrophysics. The operations team re-gained almost regular access to the WIPP underground and the EXO-200 detector in Jan 2015 and spent calendar 2015 cleaning up the soot from the WIPP fire, assessing the damage to the EXO-200 infrastructure, correcting such damage and restarting the detector. This process was successfully carried out and culminated in the re-filling of the detector with liquid xenon, in Jan 2016. As of late Jan 2016 EXO-200 is taking data again. The collaboration is in the process of upgrading the readout electronics and restarting a radon abatement system that had been commissioned just before the Feb 2014 events. The upgraded electronics will provide lower readout noise and, in turn, better signal to background discrimination. The radon abatement system will further reduce the radon in a small air-gap between the EXO-200 cryostat and the lead shielding. In a review in Jun 2015 DOE-OS approved EXO-200 for 2.5 more years of running at the end of which we expect to improve the sensitivity to the neutrino-less double-beta decay by a factor two or three. For the last 5 years the EXO-200 detector, located in the WIPP underground, has been at the center of the hunt for new physics beyond the Standard Model of particle physics!

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Aqueous Chloride Operations Overview: Plutonium and Americium Purification/Recovery

Acqueous Chloride mission is to recover plutonium and americium from pyrochemical residues (undesirable form for utilization and storage) and generate plutonium oxide and americium oxide. Plutonium oxide is recycled into Pu metal production flowsheet. It is suitable for storage. Americium oxide is a valuable product, sold through the DOE-OS isotope sales program.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

MatMCNP V. 3.0

A code for generating MCNP material cards (MatMCNP) has been written and verified for naturally occurring, stable isotopes. The program allows for material specification as either atomic or weight percent (fractions). MatMCNP also permits the specification of enriched lithium, boron, and/or uranium. In addition to producing the material cards for MCNP, the code calculates the atomic (or number) density in atoms/barn-cm as well as the multiplier that should be used to convert neutron and gamma fluences into dose in the material specified.

Source record↗
DOE OSTI2016

Characterizing Fluence as a Function of Areal Density for 1 and 14 MeV Neutrons Transported Through Air

Computing neutron dosimetry involves transporting neutrons [n] from a source to a sink, determining the neutron heating within the sink and multiplying the neutron heating by a quality factor to compute the dose equivalent. The space and energy dependent neutron fluence is a measure of the amount of neutrons crossing a particular surface area, about a particular energy and is given in units of [n/cm{sup 2}]. Microscopic cross sections are given in units of area and vary by isotope and reaction type as a function of energy. The product of the atom density of a particular atom in a specie and the microscopic cross section of a particular reaction results in the macroscopic cross section of a particular reaction, given in units of per length [1/cm] as a function of energy. Summing the macroscopic cross sections of all isotopes, and all collisions resulting in heating, within a volume, results in a total collision heating macroscopic cross section for that volume. The product of the energy and spatial dependent collision heating macroscopic cross section and the energy and spatial dependent fluence, within an energy group, results in a collision heating reaction density for that particular reaction in that energy group. Weighting each energy group's collision heating reactions, with the corresponding energy dependent particle damage per collision heating event (usually biological damage), and then integrating over energy and volume results in the delivered dose. Therefore understanding dose delivery involves examining the spatial and energy (and time) dependent fluence behavior. Because of the coupled energy and space dependence of the heating weighting and macroscopic cross sections, the fluence is not so easily separable in energy and space; however, the energy integrated fluence can be used as a first order approximation of the relative magnitude of reactions as a function of space. Here we examine the first part in the dosimetry calculation process, transporting neutrons from source to sink, as applied to neutron transport in air, examining characteristics of the fluence. Presented here is analysis regarding the nature of the fluence peak between 10 g/cm{sup 2} and 100 g/cm{sup 2} for a typical air transport calculation. Due to the high concentration of nitrogen and oxygen isotopes of these elements, these isotopes tend to dominate the transport. From the analysis presented here, the fluence peak is the result of scatter back and forth across the peak regime, and (n,2n) has a minimal (<4%) contribution. Further evidence of minimal (n,2n) impact in the 10-100 g/cm{sup 2} span includes the 1 MeV fluence peak being so much larger than the 14 MeV peak; where 1 MeV is not above the (n,2n) threshold. Also presented here is the usefulness of using tally tagging with cell flagging to further dissect the nature of the fluence. These technologies allow us to understand the originating volume that makes a contribution to a scoring regime. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1996

Meteoritic Sulfur Isotopic Analysis

Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

Thiemens, Mark H.↗
DOE OSTI2024

Isotope Production Education and Research via a Systematic Study of Photo-nuclear Reaction Yields and Excitation Functions

A new collaboration between the New Mexico Institute of Mining and Technology, Idaho State University, and Idaho National Laboratory builds the domestic workforce in isotope production and related science and technologies by conducting research and education programs related to photo-nuclear reactions. Workforce development was identified by the Department of Energy’s Office of Science in the Reaching a New Energy Sciences Workforce (RENEW) program that seeks to engage underrepresented university students in isotope production activities. This collaboration includes coursework development, student training, and isotope production research utilizing photo-nuclear reactions at electron linear accelerators. Bremsstrahlung-weighted excitation functions and cross-sections will be measured and the use of nanomaterials to exploit kinematic recoil reactions will be investigated. Students will be hosted at the Idaho National Laboratory where mentors will provide opportunities to explore careers in nuclear science and technology. This presentation regards the ongoing progress of the research and education objectives of the collaboration that was performed under the Office of Science Isotopes Program under award number D000-22-2765.

07 ISOTOPE AND RADIATION SOURCES↗