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Calcium isotope separation by chemical exchange with polymer-bound crown compounds

Description: Chromatographic separation of calcium isotopes by chemical exchange with polymer-bound 18-crown-6 was investigated. The breakthrough technique of column chromatography was employed to determine the influence of solvent composition and ligand-tether structure on separation coefficients and heterogeneous calcium complex stability. The separation coefficient, {epsilon}, was found to be strongly dependent upon solvent composition. An {epsilon} of 0. 0025{plus minus}0.0002 (95% C.L.) for the {sup 44}Ca/{sup 40}Ca isotope pair was obtained with a 70/30 (by volume) methanol/chloroform solvent mixture at 20.0{degree}C. Differences in the structure of the tether binding the crown ring to the polymer had no influence on {epsilon} at that solvent composition. 8 refs., 5 figs., 1 tab.
Date: January 1, 1990
Creator: Jepson, B.E.
Partner: UNT Libraries Government Documents Department

Confinement properties of the RFP (Reversed Field Pinch)

Description: Research in ZT-40M has been focused on elucidating the confinement properties of the Reversed Field Pinch (RFP). Recent improvements in diagnostic capability have permitted measurement of radial profiles, as well as a detailed study of the edge plasma. The emerging confinement picture for ZT-40M has several ingredients: Typically 0.3 of the Ohmic input power to ZT-40M is available to drive fluctuations. Evidence points to this fluctuational power heating the ions. Approximately one quarter of the input power is lost through radiation, with metal impurities playing a key role. Magnetic fluctations in ZT-40M are at the percent level, as measured in the edge plasma. Extrapolating these data to small radii shows stochasticity in the core plasma. Suprathermal electrons are measured in the edge plasma. These electrons originate in the core, and transport to the edge along the fluctuating magnetic field lines. Under typical conditions, these electrons constitute the major electron energy loss channel in ZT-40M. Electrostatic fluctuations dominate the edge electron particle flux, but not the electron thermal flux. The major ion loss process is charge exchange, with smaller contributions from conduction and convection. In examining these observations, and the parametric dependences of confinement, a working model for RFP confinement emerges. An overview of this model, together with implications for the multi-mega-ampere ZTH experiment will be presented.
Date: January 1, 1990
Creator: Weber, P.G.; Schoenberg, K.F.; Ingraham, J.C.; Miller, G.; Munson, C.P.; Pickrell, M.M. et al.
Partner: UNT Libraries Government Documents Department

Confinement studies in the ZT-40M reversed field pinch

Description: Measurement of electrostatic and magnetic fluctuations in the ZT-40M Reversed Field Pinch (RFP) are used to estimate fluctuation driven transport. Edge electrostatic fluctuations appear to explain edge particle transport, analogously to some tokamak and stellarator observations. However, in contrast to tokamaks, electrostatic fluctuations do not explain the heat flux through the edge. Instead, transport of suprathermal electrons along fluctuating magnetic field lines constitute the major electron heat loss. Ion losses in ZT-40M appear to be dominated by charge exchange.
Date: January 1, 1990
Creator: Weber, P.G.; Schoenberg, K.F.; Ingraham, J.C.; Miller, G.; Moses, R.W.; Munson, C.P. et al.
Partner: UNT Libraries Government Documents Department

Fast electron studies in the ZT-40M edge plasma

Description: Measurements of the edge plasma on the ZT-40M Reversed Field Pinch (RFP) show the presence of a dilute (1 to 10 per cent of the edge density), fast (T{sub H} {approx equal} (2 {minus} 3)T{sub {epsilon}0}) electron tail with a nearly unidirectional flow along B in a toroidal sense that is against the external applied electric field force. These studies have been extended over a wide range of operating conditions including high density and krypton-injected radiation-dominated (P{sub RAD} {approx equal} 0.9 P{sub IN}) discharges. In all cases the current density of the fast electrons is sufficient to account for the current density required to maintain the RFP. For low current 60 kA discharges this result has been confirmed in to a depth 20 mm inside of the reversal surface suggesting that the source of the fast electrons is the core of the discharge. The fast electrons also carry a large power flux parallel to B (several hundreds of MW/m{sup 2}, typically), and radial transport measurements of the fast electrons in the shadow of a movable limiter for 120 kA standard discharges indicate that the fast electrons are the primary electron energy loss channel. The fast electrons are a significant energy loss channel for a broad range of other cases as well. The collisionality of the fast electrons varies widely over the range of cases studied and it is noted that a small backflowing component of fast electrons increases in relative size as the collisionality increases. An estimate of the magnetic field stochastic diffusivity at the edge is made from the fast electron limiter shadow measurements and shows that the stochasticity of the magnetic field is low at the edge relative to the core, in agreement with magnetic fluctuation diffusivity measurements and MHD simulations. 35 refs., 10 figs.
Date: January 1, 1990
Creator: Ingraham, J.C.; Ellis, R.F.; Downing, J.N.; Miller, G.; Munson, C.P.; Pickrell, M.M. et al.
Partner: UNT Libraries Government Documents Department

First in-beam. gamma. -ray study of sup 67 As

Description: Excited states of the neutron-deficient nucleus {sup 67}As were populated using the {sup 40}Ca({sup 32}S,{alpha}p){sup 67}As and the {sup 40}Ca({sup 33}S,{alpha}pn){sup 67}As reactions at bombarding energies between 95 and 110 MeV. We present a tentative level scheme for {sup 67}As, derived from {gamma}-{gamma} coincidence studies in conjunction with measurement of evaporated charged particles and neutrons.
Date: January 1, 1990
Creator: Lang, T.F.; Moltz, D.M.; Reiff, J.E.; Batchelder, J.C.; Ognibene, T.J.; Cerny, J. et al.
Partner: UNT Libraries Government Documents Department

Kinetic and electromagnetic transport processes in toroidal devices

Description: A brief review of transport processes in toroidal devices is presented. Particular attention is given to radial transport of power by the Poynting's vector and kinetic electron flow. This work is primarily focused on the Reversed Field Pinch (RFP) which holds the added complexity of a dynamo process that sustains poloidal current in the edge region, where the toroidal field is reversed. The experimental observation of superthermal unidirectional electrons in the plasma edge of ZT-40M and HBTX1C is noted, and the rapid, nonclassical ion heating in RFPs is taken account of. Radial transport parallel to fluctuating magnetic field lines is deemed a likely candidate for both electromagnetic and kinetic energy transport. Two models are discussed and compared. It is concluded that electromagnetic transport using a local Ohm's law best describes nonclassical ion heating, and the transport of kinetic energy by long mean free path electrons best represents the half-Maxwellian of electrons observed in the edge of several RFPs. A nonlocal Ohm's law is essential for the kinetic electron model. 18 refs.
Date: January 1, 1990
Creator: Moses, R.W. & Schoenberg, K.F.
Partner: UNT Libraries Government Documents Department

Measurement of magnetic fluctuations on ZT-40(M)

Description: The mathematical basis for experimental measurement of magnetic fluctuations in a Reversed Field Pinch is reviewed. A quasi-static drift model is introduced as the frame-work for analysis of the five-fixed-probe technique. The extrapolation of edge-measured {rvec B}{sub r} fluctuations into the plasma is discussed. Correlations between magnetic and other fluctuations expected from a quasi-static model are derived and transport-relevant correlations are discussed. Data from ZT-40(M) are presented.
Date: January 1, 1990
Creator: Miller, G.
Partner: UNT Libraries Government Documents Department

A One-Body Transport Model of Fluctuation Processes in Nuclear Collisions

Description: Many aspects of a many-body system can be described in terms of one- body transport models in which the system at any time is characterized by its single-particle density rather than by the full many-body information. In these one-body models evaluation of the single-particle density is determined by a transport equation which contains the self-consistent mean-field potential and a collision term due to binary two-body collisions. Recently, this approach in a semi-classical limit with a Boltzmann-Uehling-Uhlenbeck (BUU) form of a collision term has been applied to nuclear collisions at intermediate energies. Common to all one-body models, only the average effects of two-body collisions are retained in the equation of motion and higher order correlations are entirely neglected. This approximation corresponds to an ensemble averaging which is evident, for example, from the molecular chaos assumption'' introduced in derivation of Boltzmann equation. As a result, these one-body models determine the ensemble averaged single-particle density and cannot provide a description for the fluctuation processes in nuclear collisions. On the other hand, at low and intermediate energies dynamical fluctuations are substantial due to large available phase space for decay into many final states. Therefore, it is of great interest to improve one-body transport models by incorporating dynamical fluctuations due to high order correlations into the equation of motion. 5 refs., 3 figs.
Date: January 1, 1990
Creator: Ayik, S.; Gregoire, C.; Suraud, E.; Stryjewski, J. & Belkacem, M.
Partner: UNT Libraries Government Documents Department

rvec p + sup 13 rvec C elastic scattering at 500 MeV

Description: For the first time, an elastic scattering experiment was performed at LAMPF using polarized protons and a polarized target nucleus ({rvec p} + {sup 13}{rvec C}). The analyzing powers (A{sub ooon}({Theta})) and (A{sub oonn}({Theta})) were measured using an incident beam energy of 500 MeV over the laboratory angular range of 10{degree}--30{degree}. Motivation for the experiment and some preliminary results and conclusions are presented. 12 refs., 7 figs.
Date: January 1, 1990
Creator: Tanaka, N.
Partner: UNT Libraries Government Documents Department

Spectroscopic studies near the proton drip line

Description: We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.
Date: January 1, 1990
Creator: Toth, K.S. (Oak Ridge National Lab., TN (USA)); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. (Lawrence Berkeley Lab., CA (USA)) & Robertson, J.D. (Kentucky Univ., Lexington, KY (USA))
Partner: UNT Libraries Government Documents Department

Sub-barrier fusion and near-barrier quasi-elastic scattering

Description: Elastic scattering of {sup 32}S on {sup 58,64}Ni and fusion of {sup 32}S+{sup 58,64}Ni and {sup 34}S+{sup 64}Ni have been measured at energies near the Coulomb barrier. Our results differ in several important respects from previous measurements on these systems. Coupled-channels calculations which explicitly allow for inelastic excitation and single-nucleon transfer reproduce the main features of the new data. Near-barrier elastic scattering of {sup 48}Ca on {sup 40}Ca has also been measured. These data provide evidence for the effect of strong coupling to positive Q-value channels other than single-nucleon transfer. 18 refs., 3 figs.
Date: January 1, 1990
Creator: Kolata, J.J.; Tighe, R.J. (Notre Dame Univ., IN (USA). Dept. of Physics); Fricke, S.H.; Esbensen, H. & Landowne, S. (Argonne National Lab., IL (USA))
Partner: UNT Libraries Government Documents Department

Update of ZTH physics and design issues and physics goals of ZTH and role in the Fusion Program

Description: The ZTH construction program is scheduled for completion in December of 1992. Some design features are still amenable to changes directed by new physics or computational information. Numerical results for the ZTH tapered poloidal field gap show that a relatively simple linear taper results in substantial reduction in field error. This design is simpler to manufacture compared with the compound curve predicted by analytical calculations. Also, ongoing analysis of ZT-40M data indicates that the fluctuation levels of magnetic fields and x-rays at high {theta} (1.7), can be reduced to the fluctuation levels at standard'' operational {theta} (1.4) by changing the winding configuration of the toroidal field (TF) coils. The effect is thought to depend on the shell-like action of the TF coils when they consist of many turns in parallel. Magnetic-field effects, such as field errors, at the unshielded toroidal-field butt-joint gap in the shell can be reduced by this effective external shell. Design implications for installing a second low-current TF coil on ZTH are presented. ZTH has the capability of operating at 4 MA with the addition of power supplies. The projected parameters of ZTH are discussed in the context of various conceptual design. The sensitivity of the conceptual design to the physics results from machines like RFX and ZTH is reviewed. It is shown that the 4 MA ZTH physics results will make a significant advance for the RFP program toward the programmatic RFP fusion goals. Finally, the influence of RFP and tokamak physics on the conceptual design of high mass-power-density (MPD) fusion reactors is investigated through the TITAN and ARIES studies. The confinement characteristics required of these conceptual designs are compared; physics issues are identified that are required to bring the MPD and fusion-power-core of the tokamak designs into coincidence with the RFP designs.
Date: January 1, 1990
Creator: DiMarco, J.N.
Partner: UNT Libraries Government Documents Department

Binary and multifragment decay of very hot nuclei

Description: Compound binary emission of complex fragments is illustrated for a variety of reactions. Complex fragment emission from 35 and 40 MeV/N {sup 139}La + {sup 12}C, {sup 27}Al, {sup 40}Ca and {sup 51}V reactions has been studied. Multifragment events from these reactions were assigned to sources characterized by their energy and mass through the incomplete-fusion-model kinematics. Excitation functions for the various multifragment channels appear to be nearly independent of the system and bombarding energy. Preliminary comparisons of the data with sequential-statistical-decay calculations are discussed. 14 refs., 7 figs.
Date: May 1, 1990
Creator: Moretto, L.G.; Blumenfeld, Y.; Charity, R.J. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department

Results from Nevada Nuclear Waste Storage Investigations (NNWSI) Series 3 spent fuel dissolution tests

Description: The dissolution and radionuclide release behavior of spent fuel in groundwater is being studied by the Yucca Mountain Project (YMP), formerly the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. Specimens prepared from pressurized water reactor fuel rod segments were tested in sealed stainless steel vessels in Nevada Test Site J-13 well water at 85{degree}C and 25{degree}C. The test matrix included three specimens of bare-fuel particles plus cladding hulls, two fuel rod segments with artificially defected cladding and water-tight end fittings, and an undefected fuel rod section with watertight end fittings. Periodic solution samples were taken during test cycles with the sample volumes replenished with fresh J-13 water. Test cycles were periodically terminated and the specimens restarted in fresh J-13 water. The specimens were run for three cycles for a total test duration of 15 months. 22 refs., 32 figs., 26 tabs.
Date: June 1, 1990
Creator: Wilson, C.N.
Partner: UNT Libraries Government Documents Department

Molecular iodine absolute frequencies. Final report

Description: Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.
Date: June 25, 1990
Creator: Sansonetti, C. J.
Partner: UNT Libraries Government Documents Department

Complex fragment emission in binary and multifragment decay of very hot nuclear systems

Description: Low-energy compound nucleus emission of complex fragments in the reaction {sup 63}Cu + {sup 12}C is used to infer the associated ridge-line potential. Compound binary emission of complex fragments at higher energies is illustrated for a variety of reactions. Complex fragment emission from 35 and 40 MeV/N {sup 139}La + {sup 12}C, {sup 27}Al, {sup 40}Ca and {sup 51}V reactions has been studied. Multifragment events from these reactions were assigned to sources characterized by their energy and mass through the incomplete-fusion-model kinematics. Excitation functions for the various multifragment channels appear to be nearly independent of the system and bombarding energy. Preliminary comparisons of the data with sequential-statistical-decay calculations are discussed.
Date: July 1, 1990
Creator: Moretto, L.G.; Blumenfeld, Y.; Delis, D. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department

Molecular detection using Rydberg, autoionizing, and cluster states. Progress report

Description: The author reports on investigations of multiphoton ionization spectroscopy in pure clusters of aromatic molecules and mixed clusters of an aromatic molecule with a rare gas atom. Conditions needed for efficient production of ion clusters are discussed. Experimental results that establish geometry of naphthalene and benzene clusters are described.
Date: August 15, 1990
Creator: Wessel, J.
Partner: UNT Libraries Government Documents Department

A systematic study of actinide production from the interactions of heavy ions with sup 248 Cm

Description: Production cross sections for heavy actinides produced from the interactions of {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca ions with {sup 248}Cm were measured at energies ranging from 0.98 to 1.35 X Coulomb barrier. The recoiling reaction products were collected in copper or gold catcher foils located near the {sup 248}Cm target. Separate fractions of Bk, Cf, Es, Fm, and Md were obtained from a radiochemical separation procedure. For the {sup 12}C system, a He/KCl jet was used to transport the recoiling No activities of interest to a rotating wheel system. The isotopic distributions of the actinide products were found to be essentially symmetric about the maximum with full-widths-at-half-maximum of approximately 2.5 mass units. Isotopic distributions of the {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca systems were found to be very similar to the {sup 40,48}Ca systems studied previously. The maxima of the isotopic distributions generally occurred for those reaction channels which involved the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy was a positive quantity. Additionally, the maxima of the excitation functions occurred at those projectile energies which were consistent with the calculated reaction barriers based upon a binary reaction mechanism. The experimental data from the four systems investigated were compared to several models of heavy ion interactions including a damped reaction mechanism, compound nucleus formation and subsequent particle evaporation, and classical partial wave calculations for binary systems.
Date: September 7, 1990
Creator: Leyba, J.D.
Partner: UNT Libraries Government Documents Department

1990 Fischer Standard study

Description: The purpose of this work is to develop a set of Titanium areal density standards for calibration and maintenance of the Fischer`s X-ray Fluorescence measurement system characterization curve program. The electron microprobe was calibrated for Titanium films on ceramic substrates using an existing set of laboratory standards (Quantity: 6 Range: 0.310 to 1.605). Fourteen source assemblies were measured and assigned values. These values are based on a mean calculation, of five separate readings, from best curve fit equations developed form the plot of the laboratory standards areal density (Source Measure) versus electron microprobe measurement (reading). The best fit equations were determined using the SAS General Linear Modeling (GLM) procedure. Four separate best fit equations were evaluated (Linear, Quadratic, Cubic and Exponential). Areal density values for the Fischer Standards appear here ordered by best fit equation based on maximum R{sup 2}.
Date: September 12, 1990
Creator: Roubik, G.J.
Partner: UNT Libraries Government Documents Department

Hanford Environmental Dose Reconstruction Project Monthly Report

Description: This monthly report summarizes the technical progress and project status for the Hanford Environmental Dose Reconstruction (HEDR) Project being conducted at the Pacific Northwest Laboratory (PNL) under the direction of a Technical Steering Panel (TSP). The TSP is composed of experts in numerous technical fields related to this project and represents the interests of the public. The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on humans (dose estimates): source terms, environmental transport, environmental monitoring data, demographics, agriculture, food habits, and environmental pathways and dose estimates. 3 figs., 3 tabs.
Date: October 1990
Creator: Finch, S. M.
Partner: UNT Libraries Government Documents Department

Heavy residue properties in intermediate energy nuclear collisions with gold

Description: We have measured the target fragment production cross sections and angular distributions for the interaction of 32, 44 and 93 MeV/nucleon argon, 35 and 43 MeV/nucleon krypton with gold. The fragment isobaric yield distributions, moving frame angular distributions and velocities have been deduced from these data. This fission cross section decreases with increasing projectile energy and the heavy residue cross section increases. The ratio v{sub {parallel}}/v{sub cn} increases approximately linearly with mass removed from the target. 21 refs., 8 figs.
Date: October 1, 1990
Creator: Aleklett, K.; Sihver, L. (Uppsala Univ., Nykoeping (Sweden). Studsvik Neutron Research Lab.); Loveland, W. (Oregon State Univ., Corvallis, OR (USA)); Liljenzin, J.O. (Chalmers Univ. of Tech., Goeteborg (Sweden)) & Seaborg, G.T. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)
Partner: UNT Libraries Government Documents Department

Relativistic heavy ion fragmentation at HISS (Heavy Ion Spectrometer System)

Description: An experiment was conducted at the Lawrence Berkeley Laboratory to measure projectile fragmentation of relativistic heavy ions. Charge identification was obtained by the use of a Cerenkov Hodoscope operating above the threshold for total internal reflection, while velocity measurement was performed by use of a second set of Cerenkov radiators operating at the threshold for total internal reflection. Charge and mass resolution for the system was {sigma}{sub Z} = 0.2 e and {sigma}{sub A} = 0.2 u. Measurements of the elemental and isotopic production cross sections for the fragmentation of {sup 40}Ar at 1.65{center dot}A GeV have been compared with an Abrasion-Ablation Model based on the evaporation computer code GEMINI. The model proves to be an accurate predictor of the cross sections for fragments between Chlorine and Boron. The measured cross section were reproduced using simple geometry with charge dispersions induced by zero-point vibrations of the giant dipole resonance for the prompt abrasion stage, and injecting an excitation energy spectrum based on a final state interaction with scaling factor E{sub fsi} = 38.8 MeV/c. Measurement of the longitudinal momentum distribution widths for projectile fragments are consistent with previous experiment and can be interpreted as reflecting the Fermi momentum distribution in the initial projectile nucleus. Measurement of the transverse momentum indicate an additional, unexplained dependence of the reduced momentum widths on fragment mass. This dependence has the same sign and similar slope to previously measured fragments of {sup 139}La, and to predictions based on phase-space constraints on the final state of the system.
Date: October 1, 1990
Creator: Tull, C.E.
Partner: UNT Libraries Government Documents Department