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Valence proton-neutron interaction strengths from double binding energy differences

Description: Empirical p-n interaction strengths have been extracted from experimental mass data using double-difference binding energy equations. The especially strong interactions for self-conjugate nuclei will be discussed as well as microstructure found for deformed and in doubly magic regions. Valence correlation Schemes provide a basis to comment on the stability of medium mass near-drip-line nuclei and superheavy elements.
Date: 1996-10~
Creator: Brenner, D. S.; Foy, B. D.; Warner, D. D.; Zamfir, N. V. & Casten, R. F.
Partner: UNT Libraries Government Documents Department

Theory of Moessbauer line broadening due to diffusion

Description: We have calculated the line broadening of the Moessbauer line due to diffusion of Moessbauer atoms via single vacanices. We take into account the perturbation of vacancy jumps in the neighbourhood of an impurity Moessbauer atom (e.g. Fe in Al) using the 5-frequency model. The anisotropy of the line width is given by the Fourier transform of the final distribution of a Moessbauer atom after an encounter with a vacancy. This distribution is calculated by Monte Carlo computer simulation. 3 figures, 1 tables.
Date: December 1, 1981
Creator: Schroeder, K.; Wolf, D. & Dederichs, P.H.
Partner: UNT Libraries Government Documents Department

FY99 Status Report on the HSV

Description: 'The HSV in storage in MTF has been monitored during FY99, and its overpressure has been sampled and analyzed. The HSV''s internal pressure continues to rise slowly, and the overpressure still analyzes as 100 percent 3He. The titanium tritide sample that was to be monitored annually and which had developed a leak last year has been repaired and isotherms measured. Unfortunately the sample was showing significant unexpected 3He release, so the isotherm data is corrupted by unknown levels of 3He. This release has disqualified this sample for future use, as it is now seriously divergent from the HSV material. A different sample must be selected for subsequent studies.The unexpected 3He releases of the Ti-3 sample and the possible release in other Ti samples have raised a serious issue. It should be determined why this release is occurring, so that an unexpected release of 3He during HSV unloading can be assessed as unlikely.'
Date: October 15, 1999
Creator: Shanahan, K. L.
Partner: UNT Libraries Government Documents Department

FY99 Status Report on the HSV

Description: 'The HSV in storage in MTF has been monitored during FY99, and its overpressure has been sampled and analyzed. The HSV''s internal pressure continues to rise slowly, and the overpressure still analyzes as 100 percent 3He. The titanium tritide sample that was to be monitored annually and which had developed a leak last year has been repaired and isotherms measured. Unfortunately the sample was showing significant unexpected 3He release, so the isotherm data is corrupted by unknown levels of 3He. This release has disqualified this sample for future use, as it is now seriously divergent from the HSV material. A different sample must be selected for subsequent studies.The unexpected 3He releases of the Ti-3 sample and the possible release in other Ti samples have raised a serious issue. It should be determined why this release is occurring, so that an unexpected release of 3He during HSV unloading can be assessed as unlikely.'
Date: October 15, 1999
Creator: Shanahan, K.L.
Partner: UNT Libraries Government Documents Department

Vibrational soliton: an experimental overview

Description: To date the most convincing evidence of vibrational solitons in biopolymers has been found in two very disparate systems: Davydov-like excitations in hydrogen-bonded linear chains (acetanilide and N-methylacetamide) which are not biopolymers but plausible structural paradigms for biopolymers, and longitudinal accoustic modes of possibly nonlinear character in biologically viable DNA. 17 refs., 4 figs.
Date: March 8, 1986
Creator: Bigio, I.J.
Partner: UNT Libraries Government Documents Department

Sound propagation in normal and superfluid /sup 3/He

Description: Liquid /sup 3/He, despite the rather simple nature of its interatomic force, displays striking properties at ultralow temperatures. Below about 2 x 10/sup -3/ K it behaves as a superfluid whose properties are related to, but are much more varied and complex than, those of superconducting electrons in metals. Ultrasonic waves prove to be a powerful probe of this system; here the acoustic properties of both the normal and superfluid phases of this liquid are briefly reviewed.
Date: January 1, 1977
Creator: Ketterson, J.B. & Roach, P.R.
Partner: UNT Libraries Government Documents Department

The superfluid Stirling refrigerator, a new method for cooling below 0. 5 K

Description: A new subkelvin refrigerator, the superfluid Stirling cycle refrigerator, uses a working fluid of [sup 3]He-[sup 4]He mixture in a Stirling cycle. The thermodynamically active components of the mixture are the [sup 3]He, which behaves like a Boltzman gas, and the phonon-roton gas in the [sup 4]He. The superfluid component of the liquid is inert. Two refrigerators have been built and temperatures of 340 mK have been achieved.
Date: April 9, 1993
Creator: Brisson, J.G.; Kotsubo, V. & Swift, G.W.
Partner: UNT Libraries Government Documents Department

New data on the heat capacity of liquid /sup 3/He

Description: Recent heat capacity measurements on liquid /sup 3/He by Haavasoja have shown much smaller values than previous measurements by Wheatley. We have measured P/sub v/(T) from which we can derive values for par. deltaC/sub v/par. delta v. A comparison with values of par. deltaC/sub v//par. delta v obtained from the actual heat capacity measurements shows agreement between our data and those from the heat capacities of Wheatley but disagreement with those from the heat capacities of Haavasoja. This suggests that the large discrepancy between the two sets of heat capacities originates with a problem in the data of Haavasoja.
Date: January 1, 1981
Creator: Roach, P.R.; Eckstein, Y. & Meisel, M.W.
Partner: UNT Libraries Government Documents Department

Effective interactions, elementary excitations, and transport in the helium liquids

Description: Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid /sup 4/He and /sup 3/He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of /sup 4/He and /sup 3/He-/sup 4/He mixtures, the phonon-maxon spectrum of normal and spin-polarized /sup 3/He, and the transport properties of superfluid /sup 4/He and of normal and spin-polarized /sup 3/He.
Date: January 1, 1986
Creator: Pines, D.
Partner: UNT Libraries Government Documents Department

Effect of interacting particles on primordial nucleosynthesis

Description: We modify the standard model for big-bang nucleosynthesis to allow for the presence of a generic particle species, i.e., one which maintains good thermal contact with either the photons or the light neutrino species throughout the epoch of primordial nucleosynthesis. The production of D, /sup 3/He, /sup 4/He, and /sup 7/Li is calculated as a function of the mass, degrees of freedom, and spin statistics of the generic particle. We show that in general, the effect of an additional generic species cannot simply be parameterized as the equivalent number of additional light neutrino species. The presence of generic particles also affects the predicted value for the neutrino-to-photon temperature ratio.
Date: May 1, 1986
Creator: Kolb, E.W.; Turner, M.S. & Walker, T.P.
Partner: UNT Libraries Government Documents Department

(Medium energy spin physics with lasers)

Description: During the first two years of this program, we have successfully investigated two new methods for the production of polarized muonic helium. This work was done at LAMPF in collarboration with a group from Syracuse University. Traditionally, polarized muonic helium has been formed by stopping polarized muons in unpolarized atoms. Unfortunately, because of depolarization in the muon cascade to the ground state, residual polarizations are only {approximately}3%. The two methods we have developed both achieve much higher muon polarizations. To accomplish our goals, we first developed an appropriate muon beam for use with our small gas targets. During the summer of 1990, we stopped unpolarized negative muons in nuclear polarized {sup 3}He. The muons were polarized in the cascade to the ground state through the hyperfine interaction with the nucleus. The resulting muon polarizations were 7.2 {plus minus} 0.8% for a 100% nuclear polarized target. While higher polarizations are clearly desirable for practical purposes, this experiment yielded important insights on spin interactions that occur in muonic atoms. Also, the ability to rapidly reverse the target polarization gave the experiment good sensitivity with minimal systematic effects. Last summer, we completed an experiment in which we polarized muonic helium by direct spin interaction with an optically pumped Rb vapor. In this technique, the muonic helium atom is polarized through a combination of charge exchange and spin exchange with the polarized valence electron of the Rb vapor. In contrast to the technique described in appendix A, the {sup 3}He nuclei are not polarized. This last technique yielded dramatic polarizations approaching 50%.
Date: January 1, 1992
Creator: Cates, G.D.
Partner: UNT Libraries Government Documents Department

Steam gasification of carbon: Catalyst properties

Description: This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques, with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.
Date: March 16, 1992
Creator: Falconer, J.L.
Partner: UNT Libraries Government Documents Department

Unravelling lignin formation and structure

Description: During this study, we established that the Fagaceae exclusively accumulate Z-monolignois/glucosides, and not the E-isomers. Evidence for the presence of a novel E{yields}Z isomerse has been obtained. Our pioneering work in lignin biosynthesis and structure in situ has also progressed smoothly. We established the bonding environments of a woody angiosperm, Leucanea leucocephala, as well as wheat (T. aestivum) and tobacco (N. tabacum). A cell culture system from Pinus taeda was developed which seems ideal for investigating the early stages of lignification. These cultures excrete peroxidase isozymes, considered to be specifically involved in lignin deposition. We also studied the effect of the putative lignin-degrading enzyme, lignin peroxidase, on monolignols and dehydropolymerisates therefrom. In all cases, polymerization was observed, and not degradation; these polymers are identical to that obtained with horseradish peroxidases/H{sub 2}O{sub 2}. It seems inconceivable that these enzymes can be considered as being primarily responsible for lignin biodegradation.
Date: January 1, 1991
Creator: Lewis, N.G. (Washington State Univ., Pullman, WA (United States). Inst. of Biological Chemistry)
Partner: UNT Libraries Government Documents Department

Comparison of the U-233 dog data of Stevens et al. with uranium retention functions in ICRP Publication 30 and a 3-compartment mammillary model for uranium

Description: Stevens measured the distribution, retention, and excretion of U-233 in seven beagles each given a single injection of U-233 citrate (2.8 ..mu..Ci/kg U-233 (VI) (approx.3 mg/dog)). These data, when plotted together with results obtained with the ICRP (Pub. 30) retention functions for purposes of comparison, are seen to differ only slightly from the ICRP-30 model. The number of transformations in the body, over a fifty-year period agree within a factor of 2. A three-compartment mammillary model has been parameterized from the data of Stevens by the method of Bernard. Retention in tissues of the body is represented by a linear combination of three compartments. The data plots for the dogs and ICRP-30 model will be presented and discussed together with the three compartment mammillary model for U-233 retention, distribution, and excretion. 3 figs., 2 tabs.
Date: January 1, 1983
Creator: S.R., Bernard
Partner: UNT Libraries Government Documents Department

Carbon-13 magnetic resonance of hydrocarbons. Annual report

Description: Several tetralins, tetrahydrophenanthrenes, and dihydroanthracenes were synthesized, /sup 13/C spin-lattice relaxation measurements were carried out on aromatic and hydroaromatic compounds. /sup 13/C chemical shift studies were also conducted on methylated 1,2,3,4-tetrahydronaphthalenes, 1,2,3,4-tetrahydrophenanthrenes, and 9,10-dihydroanthracenes. (DLC)
Date: January 1, 1979
Creator: Grant, D.M. & Pugmire, R.J.
Partner: UNT Libraries Government Documents Department

Active neutron technique for detecting attempted special nuclear material diversion

Description: The identification of special nuclear material (SNM) diversion is necessary if SNM inventory control is to be maintained at nuclear facilities. (Special nuclear materials are defined for this purpose as either /sup 235/U of /sup 239/Pu.) Direct SNM identification by the detection of natural decay or fission radiation is inadequate if the SNM is concealed by appropriate shielding. The active neutron interrogation technique described combines direct SNM identification by delayed fission neutron (DFN) detection with implied SNM detection by the identification of materials capable of shielding SNM from direct detection. This technique is being developed for application in an unattended material/equipment portal through which items such as electronic instruments, packages, tool boxes, etc., will pass. The volume of this portal will be 41-cm wide, 53-cm high and 76-cm deep. The objective of this technique is to identify an attempted diversion of at least 20 grams of SNM with a measurement time of 30 seconds.
Date: January 1, 1979
Creator: Smith, G.W. & Rice, L.G. III
Partner: UNT Libraries Government Documents Department

Applications and misapplications of the channel-capture formalism of direct neutron capture

Description: We discuss the channel-capture approximation of slow neutron direct-capture theory. We show that this approximation gives a generally good representation of the neutron capture cross sections for several electric dipole transitions in a broad range of nuclides from A = 9 to A = 136; these are mostly near-spherical nuclei. Despite this body of agreement, we examine the accuracy we can expect from the simple channel-capture theory. Comparison with calculations of the potential-capture cross section from physically more realistic optical model calculations show that, in general, the channel-capture cross section can be up to approx. =40% in error. In cases where the expected channel-capture cross section is much smaller than the ''hard-sphere'' capture cross-section estimate, the disagreement with potential capture can be much worse than this. Also, in these cases, compound-nucleus capture can be of comparable or greater magnitude. These effects have been shown to completely undermine recent attempts to determine nuclear interaction radii for targets, such as /sup 12/C and /sup 9/Be, by application of the channel-capture formula to capture cross-section data. 20 refs.
Date: January 1, 1985
Creator: Raman, S. & Lynn, J.E.
Partner: UNT Libraries Government Documents Department

Development of ultrafiltration and inorganic adsorbents for reducing volumes of low-level and intermediate-level liquid waste: April--June 1977

Description: Ultrafication (UF) membranes have demonstrated 90 to 98% rejection of gross alpha in laboratory tests. In the treatment of laundry wastes, rejection of activity ranged from 98 to 99.9% gross alpha. The pilot UF system was installed and started up. Flux decline curves and volume reduction performance were determined. Volume reductions of 210 : 1 were achieved at flux rates of 1.1 gal/min (system is rated at 2 to 3 gal/min, 90% recovery) at activity rejection of 99.94% gross alpha. Adsorbent studies demonstrated capacities in excess of 10/sup 9/ dis/min/g for uranium-233 and in excess of 10/sup 8/ dis/min/g for plutonium-238. Construction and start-up of the Engineering Test Facility has been completed.
Date: November 14, 1977
Creator: Koenst, J.W.; Herald, W.R. & Roberts, R.C.
Partner: UNT Libraries Government Documents Department

Coal liquefaction process streams characterization and evaluation

Description: This study clearly demonstrated the usefulness of liquid- and solid-state {sup 13}C- and {sup 1}H-NMR for the examination of process-derived materials from direct coal liquefaction. The techniques can provide data not directly obtainable by other methods to examine the saturation of aromatic rings and to determine the modes of hydrogen utilization during coal liquefaction. In addition, these methods can be used to infer the extent of condensation and retrograde reactions occurring in the direct coal liquefaction process. Five NMR techniques were employed. Solid-state {sup 13}C-NMR measurements were made using the Cross Polarization Magic Angle Spinning (CP/MAS) and Single Pulse (SP) techniques. Solid-state {sup 1}H-NMR measurements were made using the technique of Combined Rotation and Multiple-Pulse spectroscopy (CRAMPS). Conventional liquid-state {sup 12}C- and {sup 1}H-NMR techniques were employed as appropriate. Interpretation of the NMR data, once obtained, is relatively straightforward. Combined with other information, such as elemental analyses and process conversion data, the NMR data prove to be a powerful tool for the examination of direct coal liquefaction process-derived material. Further development and more wide-spread application of this analytical method as a process development tool is justified on the basis of these results.
Date: November 1, 1991
Creator: Miknis, F.P. (Western Research Inst., Laramie, WY (United States))
Partner: UNT Libraries Government Documents Department