Search for natural radioactivity of calcium-48
Chemical scandium isotope separation from calcium compounds containing radioactive calcium 48
Yeager, M. J.↗
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Results for “isotope separation”
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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Neutron emission following muon capture in Ce-142, Ce-140, Ba-138, and Sn-120.
Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed gamma rays were observed in studies of muonic Ce-142, Ce-140, Ba-138, and Sn-120, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for La-141, La-139, Cs-137, and In-119.
Lucas, G. R., Jr.↗
Superconducting magnets for space flight
The operating principle and application of superconducting magnetic spectrometers for cosmic ray analysis are described. Magnetic spectrometer experiments are thought to be possible in the areas of charge composition and its possible energy dependence, isotopic separation up to several GeV/n, electrons and positrons energy spectra, galactic secondary antiprotons, searches for primordial antimatter, searches for substructure in energy spectra, and gamma ray astronomy. Operational problems associated with the magnets are discussed, and a possible shuttle payload is also described.
Golden, R. L.↗
High power gas laser - Applications and future developments
Fast flow can be used to create the population inversion required for lasing action, or can be used to improve laser operation, for example by the removal of waste heat. It is pointed out that at the present time all lasers which are capable of continuous high-average power employ flow as an indispensable aspect of operation. High power laser systems are discussed, taking into account the gasdynamic laser, the HF supersonic diffusion laser, and electric discharge lasers. Aerodynamics and high power lasers are considered, giving attention to flow effects in high-power gas lasers, aerodynamic windows and beam manipulation, and the Venus machine. Applications of high-power laser technology reported are related to laser material working, the employment of the laser in controlled fusion machines, laser isotope separation and photochemistry, and laser power transmission.
Hertzberg, A.↗
Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field
An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.
Hong, S. H.↗
The isotopic composition of helium in the cosmic radiation above 11 gigavolts
The He-3/He-4 abundance ratio above 11 GV has been measured with a balloon-borne experiment that employs the geomagnetic method of isotope separation near earth's equator. Above a kinetic energy of approximately 6 GeV per nucleon, the He-3/He-4 ratio is measured to be 0.24 + or - 0.05 under the assumption that the helium spectrum at earth is a power law in rigidity of the form R to the -2.65th. The implied interstellar mean escape pathlength of about 15 g per sq cm, with this assumption, is considerably greater than values determined from observations of heavier elements. Propagation models more complex than the standard simple leaky box would be required to simultaneously understand the propagation of both the lighter and heavier components of cosmic rays.
Jordan, S. P.↗
A sputtering derived atomic oxygen source for studying fast atom reactions
A technique for the generation of fast atomic oxygen was developed. These atoms are created by ion beam sputtering from metal oxide surfaces. Mass resolved ion beams at energies up to 60 KeV are produced for this purpose using a 150 cm isotope separator. Studies have shown that particles sputtered with 40 KeV Ar(+) on Ta2O5 were dominantly neutral and exclusively atomic. The atomic oxygen also resided exclusively in its 3P ground state. The translational energy distribution for these atoms peaked at ca 7 eV (the metal-oxygen bond energy). Additional measurements on V2O5 yielded a bimodal distribution with the lower energy peak at ca 5 eV coinciding reasonably well with the metal-oxygen bond energy. The 7 eV source was used to investigate fast oxygen atom reactions with the 2-butene stereoisomers. Relative excitation functions for H-abstraction and pi-bond reaction were measured with trans-2-butene. The abstraction channel, although of minor relative importance at thermal energy, becomes comparable to the addition channel at 0.9 eV and dominates the high-energy regime. Structural effects on the specific channels were also found to be important at high energy.
Ferrieri, Richard A.↗
Manganese Nitride Sorption Joule-Thomson Refrigerator
Proposed sorption refrigeration system of increased power efficiency combines MnxNy sorption refrigeration stage with systems described in "Regenerative Sorption Refrigerator" (NPO-17630). Measured pressure-vs-composition isotherms for reversible chemisorption of N2 in MnxNy suggest feasibility to incorporate MnxNy chemisorption stage in Joule-Thomson cryogenic system. Discovery represents first known reversible nitrogen chemisorption compression system. Has potential in nitrogen-isotope separation, nitrogen purification, or contamination-free nitrogen compression.
Jones, Jack A.↗
Enhanced use of CLIPS at the Los Alamos National Laboratory
Early efforts for producing expert systems for engineering applications used a limited subset of C Language Integrated Production System (CLIPS) features. The implementation details of previous expert systems and of the current expert system, which is used for training operators in the control of the Isotope Separation System, are discussed.
Duerre, K. H.↗
Storage needs in future supercomputer environments
The Lawrence Livermore National Laboratory (LLNL) is a Department of Energy contractor, managed by the University of California since 1952. Major projects at the Laboratory include the Strategic Defense Initiative, nuclear weapon design, magnetic and laser fusion, laser isotope separation, and weather modeling. The Laboratory employs about 8,000 people. There are two major computer centers: The Livermore Computer Center and the National Energy Research Supercomputer Center. As we increase the computing capacity of LLNL systems and develop new applications, the need for archival capacity will increase. Rather than quantify that increase, I will discuss the hardware and software architectures that we will need to support advanced applications.
Coleman, Sam↗
Technical Considerations for Advanced Propulsion Systems
This presentation reviews concerns involving advanced propulsion systems. The problems involved with the use of Am-242m, is that it has a high "eta" plus an order of magnitude larger fission cross section than other fissionable materials, and that it is extremely rare. However other americium isotopes are much more common, but extremely effective isotopic separation is required. Deuterium-Tritium fusion is also not attractive for space propulsion applications. Because the pulsed systems cannot breed adequate amounts of tritium and it is difficult and expensive to bring tritium from Earth. The systems that do breed tritium have severely limited performance. However, other fusion processes should still be evaluated. Another problem with advanced propellants is that inefficiencies in converting the total energy generated into propellant energy can lead to tremendous heat rejection requirements. Therefore Many. advanced propulsion concepts benefit greatly from low-mass radiators.
Houts, Michael G.↗
Multiple Scattering Effects in de/dx-E Instruments for Isotopic Composition Studies
The development of cosmic ray telescopes to separate individual isotopes of heavy elements using the dE/dx-vs.-E technique depends on the incorporation of precise trajectory sensing elements into these systems. In typical implementations the particle trajectory is derived from a set of position measurements made prior to a particle's entering the first energy loss detector. The use of the trajectory obtained in this way to correct energy loss signals for the actual pathlengths through the detectors depends on the assumption that the particle trajectory is a straight line. In order to resolve iron isotopes the angles of incidence, theta the particle track must be known rather accurately.
Wiedenbeck, M. E.↗
Lead isotope systematics of some Apollo 17 soils and some separated components from 76501
Isotopic lead data from bulk samples of Apollo 17 soils were analyzed, and they define a chord in a concordia diagram, showing the presence of a component or components containing excess radiogenic lead with Pb-207/Pb-206 equal to about 1.32. The chord is distinctly different from the cataclysm chord, for which Pb-207/Pb-206 is approximately 1.45. Nitric acid analysis of plagioclase indicates lead ages of around 4.35 AE, in agreement with previous findings. Agglutinates from soil 76501,34 show loss of approximately 15% of lead.
Church, S. E.↗
A First Look at Graphite Grains from Orgueil: Morphology, Carbon, Nitrogen and Neon Isotopic Compositions of Individual, Chemically Separated Grains
Presolar graphite in Murchison has been extensively studied. It is characterized by a unique Ne isotopic composition, known as the Ne-E(L) component. According to studies by Huss and Lewis, the concentration of Ne-E(L) in Orgueil is about one order of magnitude higher than in Murchison, when normalized to the matrix. This could be due to a higher presolar graphite abundance in Orgueil, or due to a higher Ne-E concentrations per grain. The Ne isotopic compositions in individual presolar graphite grains from Murchison have been measured before. It was shown, that a third of the grains have detectable excesses in 22Ne, characteristic of the Ne-E(L) component. One grain in a hundred had a Ne-22 concentration two orders of magnitude higher than blank.
Pravdivtseva, O.↗
Voyager measurements of the isotopic composition of cosmic-ray aluminum and implications for the propagation of cosmic rays
We report a new measurement of the cosmic-ray isotopic composition of aluminum in the low-energy range form 75 to 206 MeV per nucleon.This measurement was made using the high-energy telescope of the CRS experiment on the Voyager 1 and 2 spacecraft during the time period from 1977 to 1993 with an average solar modulation level about 497 MV, roughly the same as at Earth near sunspot minimum. We obtain approximately 430 Al events of which approximately 35 are Al-26 and 395 are Al-27. The Al isotopes were separated with an average mass resolution sigma of 0.35 amu. Our interpretation of the isotopic composition of cosmic-ray aluminum is based on a standard Leaky-Box model for the interstellar propagation of cosmic-ray nuclei using the latest cross sections of the New Mexico-Saclay collaboration as well as a disk-halo diffusion model. From our observed ratio Al-26/Al-27 of 8.3 +/- 2.4 % we deduce an average interstellar density of about 0.52 (+0.26, -0.2) atoms per cu cm. This density is larger than the value of 0.28 (+0.14, -0.11) atoms per cu cm we found from an analysis of the observed abundance of the longer lived Be-10 made using data from the Voyager detectors over almost the same time interval and using essentially the same propagation program.
Lukasiak, A.↗
Results of a search for deuterium at 25-50 GC/c using a magnetic spectrometer
A method is presented for separately identifying isotopes using a Cerenkov detector and a magnet spectrometer. Simulations of the method are given for separating deuterium from protons. The simulations are compared with data gathered from the 1979 flight of the New Mexico State University balloonborne magnet spectrometer. The simulation and the data show the same general characteristics lending credence to the technique. The data show an apparent deuteron signal which is (11 + or - 3)% of the total sample in the rigidity region 38.5 to 50 GV/c. Until further background analysis and subtraction is performed this should be regarded as an upper limit to the deuteron/(deuteron+proton) ratio.
Golden, R. L.↗
The isotopic composition of helium at high rigidities
The isotopic abundance distribution of the cosmic radiation at energies beyond 1 GeV/AMU can at the present time be determined only with the geomagnetic method. A balloon-borne instrument was flown for 12 hours near the geomagnetic equator to measure the relative abundance of the helium isotopes He-3 and He-4 around 12 GV rigidity. The sharp rigidity cut-off at equatorial latitudes permitted separation of the two isotopes using a high-resolution-gas Cerenkov counter. The experiment thus confirms the predicted sharp cut-off at those latitudes and demonstrates the potential for isotopic separation of other elements, once flights of longer duration can be made.
Jordan, S. P.↗
Isotopic composition of lithium, potassium, rubidium, and strontium in lunar surface material
The isotopic composition of alkali and alkaline earth elements in the Luna 16 regolith was investigated by the method of thermionic emission, without chemical separation. The isotopic composition of the lithium in two regolith samples did not differ (within the limits 0.5 percent) from the mean of the terrestrial reference standard. At the same time, the observed difference (1 percent) in the isotopic composition of lithium between the samples requires further investigation and confirmation. The isotopic compositions of K and Rb did not differ within the limits of experimental error from the isotopic composition of the reference standard.
Zaslavskiy, V. G.↗