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Measurement of cosmogenic /sup 36/Cl/Cl in young volcanic rocks: An application of accelerator mass spectrometry in geochronology

Description: We have measured /sup 36/Cl/Cl ratios in a number of young volcanic rocks in order to test the feasibility of using /sup 36/Cl buildup as a geochronometer for materials less than about 700,000 years old. All of the analyzed rocks have been dated independently using K-Ar or other radiometric dating methods and have exposure histories that are known or can be reasonably assumed. Measured /sup 36/Cl/Cl ratios in these rocks are in good agreement with the calculated in-situ /sup 36/Cl buildup curve. These analyses indicate that AMS measurement of /sup 36/Cl buildup in young rocks is a potentially powerful new method for dating materials that had previously been undatable, and as such will have broad applications in volcanology, tectonics, geophysics, and Quaternary research.
Date: January 1, 1987
Creator: Leavy, B.D.; Phillips, F.M.; Elmore, D. & Kubik, P.W.
Partner: UNT Libraries Government Documents Department

Settling velocities in batch sedimentation. [Mixtures containing one and two sizes of resin beads, 44 and 62. mu. m in diameter]

Description: The sedimentation of mixtures containing one and two sizes of spherical particles (44 and 62 ..mu..m in diameter) was studied. Radioactive tracing with /sup 57/Co was used to measure the settling velocities. The ratio of the settling velocity U of uniformly sized particles to the velocity predicted to Stokes' law U/sub 0/ was correlated to an expression of the form U/U/sub 0/ = epsilon/sup ..cap alpha../, where epsilon is the liquid volume fraction and ..cap alpha.. is an empirical constant, determined experimentally to be 4.85. No effect of viscosity on the ratio U/U/sub 0/ was observed as the viscosity of the liquid medium was varied from 1x10/sup -3/ to 5x10/sup -3/ Pa.s. The settling velocities of particles in a bimodal mixture were fit by the same correlation; the ratio U/U/sub 0/ was independent of the concentrations of different-sized particles.
Date: October 1, 1982
Creator: Fricke, A.M. & Thompson, B.E.
Partner: UNT Libraries Government Documents Department

Alumina column Rb-82 generator

Description: The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec /sup 82/Rb was evaluated in both batches and column experiments using /sup 85/Sr and cyclotron-produced /sup 82/Sr. Comparisons of alumina, Bio-Rex 70 and Chelex 100 ion exchangers were made to determine Sr adsorption, /sup 82/Rb elution yield and Sr breakthrough. The adsorption of Sr is similar for alumina and Chelex 100 but different for Bio-Rex 70. Alumina and Chelex 100 exhibit a small fraction of poorly bound Sr which appears as higher breakthrough in the early elution volumes. The remaining Sr activity is strongly bound to these ion exchangers and the breakthrough remains stable at a lower breakthrough value through a large number of elutions. Bio-Rex 70 on the other hand does not exhibit the poorly bound Sr fraction and the breakthrough of Sr remains the lowest of the three ion exchangers through a moderate number of elutions and then the Sr breakthrough gradually increases with each additional elution.
Date: October 1, 1977
Creator: Yano, Y. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

Iodine-123 generator/iodination kit: a preliminary report

Description: Preliminary results are described of a xenon-123 filled device to serve as a combination iodine-123 generator/iodination kit. Xenon-123 is produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction /sup 127/I(p, 5n)/sup 123/Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which is crimped a multi-injection type septum. The ampoule contains a hydrogen sulfide atmosphere to assure that the iodine generated from the decay of the xenon is in the form of iodide. Following an adequate period for xenon-123 to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases are pumped off. The iodine-123 in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been promising.
Date: January 1, 1980
Creator: Richards, P; Prach, T; Srivastava, S C & Meinken, G E
Partner: UNT Libraries Government Documents Department

Higher superdeformed band members in sup 190 Hg: Evidence for a band interaction

Description: The superdeformed band of {sup 190}Hg has been traced up to a frequency {Dirac h} {ge} 0.4 MeV by combining data from several experiments. A distinct change in the slope of the dynamic moment of inertia J{sup 2} vs {Dirac h} is observed at {Dirac h} = 0.32 MeV. This result is interpreted as evidence for a band interaction at the highest frequencies. Possible interpretations are reviewed.
Date: January 1, 1992
Creator: Bearden, I.G.; Daly, P.J. (Purdue Univ., Lafayette, IN (United States)); Janssens, R.V.F.; Carpenter, M.P.; Ahmad, I.; Khoo, T.L. et al.
Partner: UNT Libraries Government Documents Department

Nuclear collectivity and complex alignment mechanisms in light tungsten and osmium nuclei

Description: During the past few years there have been significant advances in our understanding of nuclei excited into states of high angular momentum. The development of large multi-detector arrays for {gamma}-{gamma} coincidence spectroscopy studies has propelled the amount of new experimental information available and this has been complemented by notable advances in the theoretical treatments of high-spin phenomena. To provide yet a more detailed understanding of the structure of these high-spin states and to provide a stringent test of these models, we have resorted to measurements of their dynamic electromagnetic multipole moments which are a direct reflection of the collective aspects of the nuclear wave functions. For the most part, these multipole moments are obtained by lifetime measurements utilizing Doppler-shift techniques. Let me stress that the great value of lifetime measurements is that they provide the transition matrix elements without the necessity to rely on nuclear models. 24 refs., 10 figs.
Date: January 1, 1989
Creator: Johnson, N.R.
Partner: UNT Libraries Government Documents Department

Large scale isolation of /sup 82/Sr for generator production

Description: A new chemical separation process has been developed at Los Alamos for the isolation of /sup 82/Sr from irradiated molybdenum targets. Large (up to 500 gram) molybdenum metal targets are irradiated for approximately one month at LAMPF. Following irradiation, a no-carrier-added radiochemically pure strontium fraction is obtained from a chemical separation process is simpler to run and results in a purer product than the process used in the past. This new procedure has been used in the production of up to 28 Curies of /sup 82/Sr at end-of-bombardment. The product will be made available for commercial production of the /sup 82/Sr//sup 82/Rb greater system for medical use. 4 figures, 3 tables.
Date: January 1, 1983
Creator: Thomas, K.E. & Barnes, J.W.
Partner: UNT Libraries Government Documents Department

Use of high-pressure ion exchange for the production of gadolinium-153. Status report

Description: A large high-pressure ion-exchange column, which had been designed for the separation of gadolinium from europium, was tested in the laboratory. Good separations were obtained. Subsequently, columns of the same design were installed in a hot cell and have been used successfully for the separation of gadolinium-153 from irradiated natural europium. The gadolinium-153 production achieved using these columns is substantially greater than that achieved using the previous process. Rapid damage of the resin is a problem and frequent resin changes are required.
Date: April 1, 1986
Creator: Posey, J.C.
Partner: UNT Libraries Government Documents Department

Models for Type I supernovae

Description: Two rather disjoint scenarios for Type I supernovae are presented. One is based upon mass accretion by a white dwarf in a binary system. The second involves a star having some 8 to 10 times the mass of the sun which may or may not be a solitary star. Despite the apparent dissimilarities in the models it may be that each occurs to some extent in nature for they both share the possibility of producing substantial quantities of /sup 56/Ni and explosions in stars devoid of hydrogen envelopes. These are believed to be two properties that must be shared by any viable Type I model.
Date: June 17, 1980
Creator: Woosley, S.E.; Weaver, T.A. & Taam, R.E.
Partner: UNT Libraries Government Documents Department

Nuclear isomer separation

Description: We report experiments on selective photoionization of atoms containing isomeric nuclei of /sup 197/Hg. Other isomer separation techniques and their limitations are discussed.
Date: January 1, 1985
Creator: Dyer, P.
Partner: UNT Libraries Government Documents Department

Pairing interaction effects in exciton level densities

Description: Recent progress in pairing corrections for exciton state-density formulas used in pre-compound nuclear reaction theories is reviewed. These correction factors are, strictly speaking, dependent on the nuclear excitation energy U and the exciton number n. A simple formula for (U,n)-dependent pairing corrections has been derived, based on the BCS pairing equations for constant single-particle spacing, for the exciton state-density formula for one kind of Fermion. It has been shown that the constant-pairing-energy correction used in standard state-density formulas, such U{sub 0} in Gilbert and Cameron, is a limiting case of the general (U,n)-dependent results. Spin cutoff factors with pairing effects were also obtained using the same theory and parameterized into an explicit (U,n)-dependent function, thereby defining a simple exciton level-density formula for applications in quantum mechanical precompound theories. Preliminary results from extending such simple pairing-interaction representations to level-density formulas for two kinds of Fermions are summarized. The results show that the ratios in the exciton level densities in the one-Fermion and two-Fermion approaches vary with both U and n, thus likely leading to differences in calculated compound to precompound ratios. However, the differences in the spin cutoff factors in the two cases are found to be rather small. 12 refs., 3 figs.
Date: January 1, 1989
Creator: Fu, C.Y.
Partner: UNT Libraries Government Documents Department

Subcellular site and nature of intracellular cadmium in plants

Description: The mechanisms underlying heavy metal accumulation, toxicity and tolerance in higher plants are poorly understood. Since subcellular processes are undoubtedly involved in all these phenomena, it is of interest to study the extent of, subcellular site of and nature of intracellularly accumulated cadmium in higher plants. Whole plants supplied /sup 109/CdCl/sub 2/ or /sup 112/CdSO/sub 4/ accumulated Cd into roots and aerial tissues. Preparation of protoplasts from aerial tissue followed by subcellular fractionation of the protoplasts to obtain intact vacuoles, chloroplasts and cytosol revealed the presence of Cd in the cytosol but not in vacuoles or chloroplasts. Particulate materials containing other cell components were also labeled. Of the /sup 109/Cd supplied to plants, 2 to 10% was recovered in both cytosol preparations and in particulate materials. Cytosol contained proteinaceous--Cd complexes, free metal and low molecular weight Cd complexes. Labeling of protoplasts gave similar results. No evidence was obtained for the production of volatile Cd complexes in tobacco.
Date: January 1, 1979
Creator: Wagner, G.J.
Partner: UNT Libraries Government Documents Department

/sup 123/I research and production at Brookhaven

Description: The procedures for preparing high purity /sup 123/I at the BLIP using the /sup 127/I(p,5n)/sup 123/Xe reaction on an NaI target are described. The activity is supplied in a glass ampoule with anhydrous /sup 123/I deposited on the interior walls, allowing maximum flexibility in subsequent iodinations. Preliminary experience with a continuous flow target is also described. The results of a series of measurements of specific activity by neutron activation, x-ray fluorescence, uv absorption, and wet chemistry generally showed no detectable carrier. HPLC methods to analyse the chemical form of radioiodine and to characterize various iodinated radiopharmaceuticals have been developed. These methods provide higher sensitivity, speed and resolution than commonly used techniques. 19 refs., 6 figs., 2 tabs.
Date: January 1, 1985
Creator: Mausner, L.F.; Srivastava, S.C.; Mirzadeh, S.; Meinken, G.E. & Prach, T.
Partner: UNT Libraries Government Documents Department

Calculated late time spectra of supernovae

Description: We consider here the nebular phase spectra of supernovae whose late time luminosity is provided by the radioactive decay of /sup 56/Ni and /sup 56/Co synthesized in the explosion. A broad variety of supernovae are known or suspected to fall in this category. This includes all SNIa and SNIb, and at least some SNII, in particular SN1987a. At sufficiently late times the expanding supernova becomes basically nebular in character due to its decreasing optical depth. The spectra produced during this stage contain information on the density and abundance structure of the entire supernova, as opposed to spectra near maximum light which are affected only by the outermost layers. A numerical model for nebular spectrum formation is therefore potentially very valuable for answering currently outstanding questions about the post-explosion supernova structure. As an example, we can hope to determine the degree of mixing which occurs between the layers of the ''onion-skin'' abundance structure predicted by current one dimensional explosion calculations. In the sections which follow, such a numerical model is briefly described and then applied to SN1972e, a typical SNIa, SN1985f, an SNIb, and finally to SN1987a. In the case of SN1987a predicted spectra are presented for the wavelength range from 1 to 100 microns at a time 300 days after explosion. 18 refs., 6 figs.
Date: October 30, 1987
Creator: Axelrod, T.S.
Partner: UNT Libraries Government Documents Department

Novel, convenient, and nonpersistent radiotracer for environmental and energy applications

Description: A newly-available radioisotopic system, /sup 172/Hf-/sup 172/Lu, has excellent potential for tracer applications in which nuclear data acquisition must be accomplished in real time. The 6.7-day half-life of /sup 172/Lu is sufficient for a large fraction of tracer experiments, and should allow the direct incorporation of /sup 172/Lu into tests that have traditionally utilized much longer-lived radionuclides. Since /sup 172/Lu is the daughter component of a radioisotope generator, however, its effective shelf-life is determined by the half-life of its 1.9-year /sup 172/Hf parent. Consequently, the frequency of isotope procurement need not be any more extensive than investigators would normally be accustomed to. Discussion relevant to isotope production, generator operation, and nuclide acquisition is presented in this paper.
Date: March 12, 1984
Creator: Grant, P.M.
Partner: UNT Libraries Government Documents Department

Subnanosecond lifetime measurements of excited states in nuclei far from stability

Description: A system was developed to measure the lifetimes of nuclear states in the range of 0.05 to 1 nanosecond in nuclei far from stability. A Gerholm magnetic lens was placed on-line with the UNISOR mass separator to observe conversion electrons in coincidence with ..gamma.. rays detected in a plastic scintillator. With this system, the half-life of the 522 keV, O/sup +/ level in /sup 186/Hg was measured to be 155 +- 70 picoseconds. Improvements in this system should make possible on-line measurements of half-lives as short as approx. = 50 picoseconds. 12 references.
Date: January 1, 1979
Creator: Nettles, W.G.; Ramayya, A.V.; Hamilton, J.H.; Avignone, F.T. III & Carter, H.K.
Partner: UNT Libraries Government Documents Department

Observation of superdeformation in sup 191 Hg

Description: The first observation of superdeformation in the A {approx equal} 190 mass region is reported. A rotational band of 12 transitions with an average energy spacing of 37 keV, an average moment of inertia of 110 {Dirac h}{sup 2} MeV{sup {minus}1}, and an average quadrupole moment of 18 {plus minus} 3 eb has been observed in {sup 191}Hg. These results are in excellent agreement with a calculation that predicts an ellipsoidal axis ratio of 1.65:1 for the superdeformed shape in this nucleus. Evidence for another discrete superdeformed band and superdeformed structures in the quasi-continuum was also found in the data. 19 refs., 6 figs.
Date: January 1, 1989
Creator: Moore, E.F.; Janssens, R.V.F.; Chasman, R.R.; Ahmad, I.; Khoo, T.L.; Wolfs, F.L.H. et al.
Partner: UNT Libraries Government Documents Department

Physiopathology of blood platelets and development of platelets substitutes. Progress report, August 1, 1976--October 31, 1977. [/sup 51/Cr]

Description: Progress is reported on the following research projects: the effect of estrogen on platelet aggregability and thrombus formation; the antithrombotic effect of platelet inhibiting agents in a bench model of artificial kidney; the arrest of hemorrhage in severely alloimmunized thrombocytopenic patients; and in vivo elution of /sup 51/Cr from labeled platelets induced by antibody. (HLW)
Date: July 31, 1977
Creator: Baldini, M G
Partner: UNT Libraries Government Documents Department

Evaluation of an in-situ x-ray fluorescence analyzer for inorganic pollutants in sediments and water columns

Description: The applicability of an energy dispersive x-ray fluorescence spectrometer for measurement of trace elements in sediments and in water columns from Coast Guard vessels has been investigated. This investigation was conducted in both freshwater and saltwater areas and included Puget Sound, Lake Washington, Lake Union, and the ship canal in the State of Washington. The spectrometer system consisted of a solid cryogen-cooled Si(Li) detector and a /sup 109/Cd excitation source. Sediments and water columns were viewed through a 0.2 mm Be window. This study showed the feasibility of measuring trace elements at concentrations ranging from 20 to about 100 ppM. Measurements of this sensitivity with a 100 mCi /sup 109/Cd source are possible for time intervals as short as 5 minutes. This in-situ measurement capability permits the on-site mapping of pollution and avoids the problem of sediment disturbance which is inherent in the collection of grab samples of the sediment surface. Recommendations for an improved analyzer system included a detector assembly which could be towed, or allow continuous sediment surface analysis thereby recording the average composition of a large area.
Date: September 1, 1979
Creator: Wogman, N.A.
Partner: UNT Libraries Government Documents Department

Analysis of /sup 81/Kr in groundwater using laser resonance ionization spectroscopy

Description: A new analytical technique based on resonant ionization of krypton with a vacuum ultraviolet (VUV) laser source was used to determine low-level /sup 81/Kr concentrations in groundwater. The long half-life (210,000 years) and low concentration (1.3 x 10/sup 3/ /sup 81/Kr atoms per liter of modern water at 10/sup 0/C) make the detection of /sup 81/Kr by radioactive counting techniques extremely difficult. In this method, krypton gas was removed from water taken from an underground Swiss aquifer using standard cryogenic and chromatographic techniques. Stable krypton isotopes were then reduced by a factor of 10/sup 7/ by a two-stage isotopic enrichment cycle using a commercially available mass spectrometer. The enriched gas containing about 10/sup 8/ stable krypton atoms and about 10/sup 3/ atoms of /sup 81/Kr was implanted into a silicon disc. This disc was then placed in the high vacuum final counting chamber and the krypton was released by laser annealing. This chamber contained a quadrupole mass spectrometer which used a pulsed VUV laser source as the ionizer. The measured signal indicated that the sample contained 1200 (+-300) atoms of /sup 81/Kr.
Date: October 1, 1985
Creator: Kramer, S.D.; Hurst, G.S.; Chen, C.H.; Payne, M.G.; Allman, S.L.; Phillips, R.C. et al.
Partner: UNT Libraries Government Documents Department

Whole-body autoradiographic microimaging: Applications in radiopharmaceutical and drug research

Description: The whole-body autoradiographic (WBARG) microimaging technique is used for evaluation of the temporo-spatial distribution of radiolabeled molecules in intact animals as well as to determine the sites of accumulation of parent compounds and their metabolites. This technique is also very useful to determine the metabolism of a compound, toxicity, and effects of therapeutic interventions on the distribution of a compound in the whole body, by studying animals at different time intervals after injection of the radiolabeled compound. This report discusses various aspects of WBARG.
Date: January 1, 1991
Creator: Som, P. & Sacker, D.F.
Partner: UNT Libraries Government Documents Department

Description of an XRF system for multielemental analysis

Description: An X-ray fluorescence (XRF) system which uses radioisotopes in an orthogonal configuration between the source, sample, and detector is described. The advantage of such a system is that for large (bulk) samples or for in vivo measurements the background due to Compton scattering in the sample is minimized. High reproducibility for nonuniform samples is obtained by reducing the sample size and thus the effects of non-uniformity in the spatial response of such a system. Germane to any accurate analytical method is the use of proper mathematical algorithms for data evaluation. The problem is acute, in particular, when photopeaks with low counting statistics are to be analyzed. In the case of a single photopeak on flat, background optimal energy window size, which maximizes the signal-to-noise ratio, for trapezoidal intergration is described. The sensitivity and minimum detection limit at different energies together with background considerations are discussed. 13 refs., 8 figs., 2 tabs.
Date: January 1, 1986
Creator: Wielopolski, L.; Zhang, R. & Cohn, S.H.
Partner: UNT Libraries Government Documents Department

Incorporation of radiohalogens via versatile organometallic reactions: applications in radiopharmaceutical chemistry

Description: Factors that must be considered for the design of radiohalogenated radio-pharmaceuticals include the stability and availability of the substrate, the physical half-life of the radiohalogen and the in vivo stability of the radiolabel. Vinyl and phenyl radiohalogen bonds show more in vivo stability than the alkyl radiohalogen bonds. Consequently, a variety of methods suitable for the synthesis of tissue specific radiopharmaceuticals bearing a vinyl or phenyl radiohalogen have been developed involving the synthesis and halogenation of metallovinyl and phenyl intermediates. The halogens and metallation reactions include iodine and bromine and alanation, boronation, mercuration, stannylation, and thallation, respectively. 19 refs., 1 fig., 1 tab.
Date: January 1, 1985
Creator: Srivastava, P.C.; Goodman, M.M. & Knapp, F.F. Jr.
Partner: UNT Libraries Government Documents Department

Cosmic ray half life of sup 54 Mn

Description: A search for the {beta}{sup +} decay of {sup 54}Mn has established an upper limit of 4.4 {times} 10{sup {minus}8} for this branching ratio, and a lower limit of 13.3 for the log ft value for this second forbidden unique transition. Assuming that the {beta}{sup {minus}} decay branch has the same log ft value, then its partial half life must be greater than 4 {times} 10{sup 4} years. Experiments to directly measure the {beta}{sup {minus}} decay rate of {sup 54}Mn are now in progress. 6 refs., 2 figs.
Date: August 1, 1989
Creator: Norman, E.B.; Sur, B.; Vogel, K.R.; Lesko, K.T.; Larimer, R.M. & Browne, E.
Partner: UNT Libraries Government Documents Department