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Two-neutron transfer in Pt and Os nuclei and the IBA

Description: Two-neutron transfer studies in Pt and Os were investigated. The extracted relative enhancement factors in Pt were found to be in excellent agreement with the 0(6) limit predictions. The differences in transfer strength between Pt and Os (t,p) could not be reproduced within the present framework of the Interacting Boson Approximation Model. 3 figures.
Date: January 1, 1980
Creator: Cizewski, J.A.
Partner: UNT Libraries Government Documents Department

Concepts and limitations of macroparticle accelerators using travelling magnetic waves

Description: The concept of an accelerator using a travelling magnetic wave acting on magnetized projectiles is discussed. Although superconductors have a high potential as projectile material, their low critical temperature makes them unsuitable. Among ferromagnetic materials dysprosium seems to be superior. For stable suspension and guidance a high conductivity, preferably superconducting, guide sheet is necessary. Magnetic field gradients of 10/sup 9/ A/m/sup 2/ travelling at 10/sup 6/ m/s should be achievable using present state-of-the-art components; resulting accelerations are greater than or equal to 500 km/s/sup 2/. A linear accelerator for final speeds of 50 km/s needs a length of 2.5 km. Guidance forces sufficient to produce acceleration of 2 x 10/sup 6/ m/s/sup 2/ allow circular accelerators of reasonable size to achieve hypervelocities for small (50 to 100 mg) projectiles. An accelerator of 170 m diameter would surpass the best results from light gas guns. Travelling waves suitable for accelerations of the order of 10/sup 4/ m/s/sup 2/ can be produced without switching, by means of flux displacing rotors, easily adapted to circular accelerators.
Date: January 1, 1980
Creator: Wipf, S.L.
Partner: UNT Libraries Government Documents Department

Evaluation of relative detection efficiency on sets of irradiated fuel elements

Description: The accurate analysis and monitoring of the nuclear material inventory of discharged fuel elements is a critical part of the total system of safeguards for the nuclear fuel cycle. One of the nondestructive techniques used for verifying irradiated fuel elements is high-resolution gamma spectrometry. One aspect of this technique is the evaluation of the relative detection efficiency of gamma-ray detection systems. Many conditions, including the modification of fuel elements, can affect the relative detection efficiency. Assuming no detector malfunctions, relative detection efficiency at a fixed energy level should be a constant (within measurement uncertainty) for all fuel elements having the same irradiation history. An application of a Hotelling's - T/sup 2/ type statistic is presented as a method of screening measurements performed on large sets of irradiated elements and identifying possible outliers.
Date: January 1, 1980
Creator: Bement, T.R. & Phillips, J.R.
Partner: UNT Libraries Government Documents Department

Event and effectiveness models for simulating computer security. [SECSIM code, in FORTRAN]

Description: The development and application of a series of simulation codes (designated SECSIM) that are used for computer security analysis and design are described. Individual barrier characteristics are incorporated into generalized architectural reduction algorithms providing numerical indices in selected subcategories and for the system as a whole. 7 figures, 13 tables.
Date: January 1, 1978
Creator: Schelonka, E.P.
Partner: UNT Libraries Government Documents Department

Statistical analysis in nuclear accountability: a simulation approach

Description: This paper describes a computer simulation approach to modeling material balances and to deriving the limits of error attributable to measurement procedures. A new probability distribution is presented which is useful in the computer simulations. This distribution permits the investigator to assess the sensitivity of initial distributional assumptions on the computed limits of error. The simulation approach is illustrated with a case study example.
Date: January 1, 1978
Creator: Johnson, M.E.; Tietjen, G.L. & Johnson, M.M.
Partner: UNT Libraries Government Documents Department

Role of materials accounting in integrated safeguards systems for reprocessing plants

Description: Integration of materials accounting and containment/surveillance techniques for international safeguards requires careful examination and definition of suitable inspector activities for verification of operator's materials accounting data. The inspector's verification procedures are designed to protect against data falsification and/or the use of measurement uncertainties to conceal missing material. Materials accounting activities are developed to provide an effective international safeguards system when combined with containment/surveillance activities described in a companion paper.
Date: January 1, 1981
Creator: Hakkila, E.A.; Gutmacher, R.G.; Markin, J.T.; Shipley, J.P. & Whitty, W.J.
Partner: UNT Libraries Government Documents Department

Neutrinos and supernova collapse

Description: The neutrino emission resulting from stellar collapse and supernova formation is reviewed. The electron capture and consequent neutronization of the collapsing stellar matter at the end of evolution determines both the initial adiabat of core collapse as well as the trapped lepton fraction. The initial lepton fraction, Y/sub l/ = .48 supplies the pressure for neutral support of the star at the Chandrasekhar limit. High trapping values, Y/sub l/ = .4, lead to soft core collapses; low values to harder collapses. The value of Y/sub l/ is presently in dispute. The neutrino emission from initial electron capture is relatively small. A strong core-bounce shock releases both electron neutrino as well as thermal muon and tau neutrinos. Subsequent neutrino emission and cooling can sometimes lead to an unstable buoyancy gradient in the core in which case unstable core overturn is expected. Calculations have already shown the importance of the largest possible eddy or equivalently the lowest mode of overturn. Present models of low lepton trapping ratio lead to high entropy creation by the reflected shock and the stabilization of the core matter against overturn. In such cases the exterior matter must cool below an entropy of approximately s/k approx. = 2 to become unstable. This may require too long a time approximately one second for neutrino cooling from a neutrinosphere at rho approx. = 2 x 10/sup 12/ g cm/sup -3/. On the other hand, high values of Y/sub l/ such as .4 lead to softer bounces at lower density and values of the critical stabilizing entropy of 3 or higher. Under such circumstances, core overturn can still occur.
Date: October 30, 1980
Creator: Colgate, S.A. & Petschek, A.G.
Partner: UNT Libraries Government Documents Department

Differential production cross sections of multiply charged fragments in 800 MeV proton-induced spallation of carbon, aluminum, and nickel

Description: Differential production cross sections for multiply charged fragments from 800-MeV proton-induced spallation of /sup 12/C, /sup 27/Al, and natural Ni were measured at 30 and 90 degrees. The ion fragments were identified by use of time-of-flight, ..delta..E--E detector telescope capable of complete particle identification for energies as low as .25 MeV/nucleon. The very short ranges of the particles of interest required the construction of very thin detectors with minimal deadlayer material. The time-pick-off detectors and gas ionization chamber developed are unique, and represent the state-of-the-art in fast timing for time-of-flight measurements and in construction of thin detectors. The resolutions achieved allowed the cross sections of /sup 3/He, /sup 4/He, /sup 6/Li, /sup 7/Li, /sup 7/Be, /sup 9/Be, /sup 10/Be, /sup 10/B, /sup 11/B, /sup 11/C, /sup 12/C, and /sup 13/C to be determined, along with those of nitrogen and oxygen without isotope separation. The cross sections were found to have weak angular dependence. Consequently, pseudo cross sections were calculated from the 90/sup 0/ data by integrating the differential cross sections from 0 to 25 MeV for each product and multiplying by 4..pi... Pseudo theoretical cross sections were similarly calculated from theoretical differential cross sections. These differential cross sections were calculated by use of a Monte Carlo computer code which incorporated the cascade-evaporation model of high-energy nuclear reactions. Implications are drawn for modifications of the model. The results suggest reducing the transparency of the struck nucleus to pions produced in the cascade stage of the reaction model in order that a higher excitation energy be left for the evaporation stage. Also, there is some evidence that evaporations of nuclear aggregates more massive than /sup 4/He occur. Inclusion of such evaporations should improve the model. 82 figures, 1 table.
Date: September 1, 1978
Creator: Luckstead, S.C.
Partner: UNT Libraries Government Documents Department

R-matrix methods

Description: The procedures used in the application of R-matrix theory to atomic and molecular collision processes are presented. The computationally advantageous features of these methods are high-lighted, and some applications to electron scattering and photoionization are briefly discussed.
Date: January 1, 1978
Creator: Robb, W.D.
Partner: UNT Libraries Government Documents Department

ICRF oscillations of an inhomogeneous plasma cylinder

Description: We have derived a dispersion differential equation suitable for studying free and forced oscillations of a radially inhomogeneous plasma cylinder in the ion cyclotron range of frequencies (ICRF). Solving the differential equation, subject to appropriate boundary conditions, yields global eigenmodes of the cylindrical configuration; thus, our description embraces both the geometry and the physics relevant in the ICRF. The derivation begins with the equations of the Vlasov(ion)-fluid(electron) model. An approximate solution of the ion Vlasov equation is obtained analytically for a general screw pinch equilibrium by restricting the ion gyroradius to small, but finite values.
Date: January 1, 1981
Creator: Cayton, T.E. & Lewis, H.R.
Partner: UNT Libraries Government Documents Department

Vacuum interrupters and thyratrons as opening switches

Description: The clear advantages of inductive storage for large scale energy storage applications are creating an increasing interest in the research and development of the opening switches required. Opening switches for single-shot inductive transfers have received considerable attention and are fairly well advanced. The problem addressed by this workshop of high power opening switches for high repetition rate applications is much more severe, however, and may well require a major research and development effort. Two candidates for such an opening switch, the triggered vacuum interrupter and the magnetically quenched thyratron, are discussed. By electrically retriggering the discharge in the vacuum interrupter between pulses, the dependence on mechanical motion is eliminated. This should enable repetition rate operation at 10 to 15 kHz while still maintaining the vacuum interrupter's proven interrupting performance of tens of kiloamps at tens of kilovolts. The magnetically quenched thyratron, on the other hand, uses a cross magnetic field to raise the switch impedance by decreasing the electron mobility and driving the discharge into an arc chute wall where it is quenched. Successful interruptions of 1 kA at 15 kV and 100 A at 50 kV after conduction for 10 ..mu..s have been demonstrated by previous researchers. Work at Los Alamos is directed toward understanding the basic mechanisms involved and increasing the switch ratings, particularly the conduction time.
Date: January 1, 1981
Creator: Honig, E.M.
Partner: UNT Libraries Government Documents Department

Initial ionization stage of FRC formation

Description: A Field-Reversed Configuration (FRC) is a prolate compact torus that is confined by poloidal fields only. Theta-pinch formation of an FRC employs an initial bias field, B/sub 1/, whose direction is opposite to that of the main theta-pinch field. Some fraction of the flux associated with this bias field eventually constitutes the closed-field-line flux of the FRC. Experimental and theoretical evidence suggest that the longest-lived FRC's are obtained when the closed flux is maximized. Because the initial ionization is done in the presence of the bias field, the actual bias flux available at the time of application of the main theta-pinch field depends strongly on the initial ionization, or preionization, technique used. In this paper we report on experiments characterizing the previously used theta-pinch preionization technique that employed a net field (bias plus preionization) null, or zero-crossing, of the axial component of the magnetic field to break down the gas. We also discuss results of experiments designed to develop preionization techniques in which the gas breakdown is not accomplished by a zero-crossing.
Date: January 1, 1980
Creator: Commisso, R.J.; Armstrong, W.T.; Cochrane, J.C.; Ekdahl, C.A.; Lipson, J.; Linford, R.K. et al.
Partner: UNT Libraries Government Documents Department

Reactor technology. Progress report, January--March 1978

Description: Progress is reported in eight program areas. The nuclear Space Electric Power Supply Program examined safety questions in the aftermath of the COSMOS 954 incident, examined the use of thermoelectric converters, examined the neutronic effectiveness of various reflecting materials, examined ways of connecting heat pipes to one another, studied the consequences of the failure of one heat pipe in the reactor core, and did conceptual design work on heat radiators for various power supplies. The Heat Pipe Program reported progress in the design of ceramic heat pipes, new application of heat pipes to solar collectors, and final performance tests of two pipes for HEDL applications. Under the Nuclear Process Heat Program, work continues on computer codes to model a pebble bed high-temperature gas-cooled reactor, adaptation of a set of German reactor calculation codes to use on U.S. computers, and a parametric study of a certain resonance integral required in reactor studies. Under the Nonproliferation Alternative Sources Assessment Program LASL has undertaken an evaluation of a study of gaseous core reactors by Southern Science Applications, Inc. Independently LASL has developed a proposal for a comprehensive study of gaseous uranium-fueled reactor technology. The Plasma Core Reactor Program has concentrated on restacking the beryllium reflector and redesigning the nuclear control system. The status of and experiments on four critical assemblies, SKUA, Godiva IV, Big Ten, and Flattop, are reported. The Nuclear Criticality Safety Program carried out several tasks including conducting a course, doing several annual safety reviews and evaluating the safety of two Nevada test devices. During the quarter one of the groups involved in reactor technology has acquired responsibility for the operation of a Cockroft-Walton accelerator. The present report contains information on the use of machine and improvements being made in its operation.
Date: July 1, 1978
Creator: Warren, J.L. (ed.)
Partner: UNT Libraries Government Documents Department

PIGMI technology. [100-. mu. A, 650-MeV p]

Description: The accelerator technologies relevant to the design of a medically practical pion generator for medical irradiations (PIGMI) have been identified and developed. A base-case design for PIGMI is presented here. The accelerator portion of the PIGMI facility consists of an injector, an rf quadrupole linac structure, a drift-tube linac structure, a coupled-cavity linac structure, 1 440-MHz rf system, six 1320-MHz rf systems, and a control and instrumentation system. Each of these components is described in some detail. A 100-..mu..A, 650-MeV proton beam is anticipated. 24 figures, 2 tables. (RWR)
Date: January 1, 1980
Creator: Swenson, D.A.
Partner: UNT Libraries Government Documents Department

Summary of the setting, air quality problems, and meteorological activities in the oil shale region

Description: This document discusses air quality problems that may arise in the valleys of the Uinta mountains and the Roan Ridge in the oil shale area in western Colorado and eastern Utah. A meteorological field expedition that was undertaken in August 1980 by LASL and PNL is described. (DLC)
Date: January 1, 1981
Creator: Barr, S. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Newly discovered failure mode in high energy density, energy storage capacitors

Description: High energy density pulse capacitors, typified by the 10-kV, 170-..mu..F unit, have become widely used in recent years. These units primarily were designed for lower cost and higher energy per unit volume. The life characteristics of these units have never been determined fully, but they have already been shown capable of lives much longer than originally expected. The Los Alamos Scientific Laboratory is now conducting an extended program to determine the long-term capabilities of these capacitors. This program is aimed not only at finding the statistical parameters of the failure distribution but also at determining the physical failure modes characteristic of such units. Recently, a new failure mode was found. This failure mode has prevented test samples of polypropylene-paper-dioctyl phthalate units from actually reaching the true potential life of the insulation. In this report, the new failure mechanism is examined and suggestions are made that could eliminate the failure mode.
Date: July 1, 1978
Creator: Boicourt, G.P. & Kemp, E.L.
Partner: UNT Libraries Government Documents Department

Gaseous fuel reactors for power systems

Description: The Los Alamos Scientific Laboratory is participating in a NASA-sponsored program to demonstrate the feasibility of a gaseous uranium fueled reactor. The work is aimed at acquiring experimental and theoretical information for the design of a prototype plasma core reactor which will test heat removal by optical radiation. The basic goal of this work is for space applications, however, other NASA-sponsored work suggests several attractive applications to help meet earth-bound energy needs. Such potential benefits are small critical mass, on-site fuel processing, high fuel burnup, low fission fragment inventory in reactor core, high temperature for process heat, optical radiation for photochemistry and space power transmission, and high temperature for advanced propulsion systems. Low power reactor experiments using uranium hexafluoride gas as fuel demonstrated performance in accordance with reactor physics predictions. The final phase of experimental activity now in progress is the fabrication and testing of a buffer gas vortex confinement system.
Date: January 1, 1978
Creator: Helmick, H.H. & Schwenk, F.C.
Partner: UNT Libraries Government Documents Department

Pulse propagation in a one-atmosphere CO/sub 2/ laser amplifier

Description: The theoretical propagation of short (150-ps) laser pulses in a one-atmosphere CO/sub 2/ amplifier is investigated using a fully coherent density-matrix computer code. The influence of coherent effects and of the response times of the amplifying medium on the temporal shape of the output pulse is examined. It is found that short pulses, whose width is approximately equal to the T/sub 2/ time of the medium, can be effectively amplified.
Date: December 15, 1980
Creator: Czuchlewski, S.J.
Partner: UNT Libraries Government Documents Department

Theoretical mean colors for RR Lyrae variables. [Computer code, variable Eddington radiation approximation]

Description: A hydrodynamically pulsating 0.6 M/sub solar/ model of a typical RR Lyrae variable was studied with a radiation transport-hydrodynamic computer program to predict theoretical T/sub e/ and colors at many phases and to find the proper methods for getting mean colors and the consequent mean effective temperatures. The variable Eddington radiation approximation method was used with gray and with multifrequency absorption coefficients to represent the radiation flow in the outer optically thin layers. Comparison between observed and computed B-V colors indicates that these low Z Population II models are reasonably accurate using King 1A composition opacities. The well known Oke, Giver, and Searle relation between B-V and T/sub e/ is reproduced. Mean colors are found by four different averaging methods. The method that gives a mean color and the mean T/sub e/ closest to the nonpulsating model was the separate intensity means of B and V, just as the case for previous studies of classical Cepheids. The best mean for T/sub e/, which is known for all pulsation phases from four color observations of real RR Lyrae variables or from the calculated model, is a time average of T/sub e/ without any weighting function.
Date: January 1, 1978
Creator: Davis, C.G. & Cox, A.N.
Partner: UNT Libraries Government Documents Department

Startup of the RFP in a quasi-adiabatic mode

Description: The equations describing the purely adiabatic formation of the reversed-field pinch are solved. This method of formation in principle remedies the problem of flux consumption during the startup phase of this device.
Date: January 1, 1980
Creator: Caramana, E.J.
Partner: UNT Libraries Government Documents Department

Development of samarium--cobalt quadrupole lenses for particle accelerator applications. [Computer code PANDIRA]

Description: A family of samarium-cobalt permanent magnet quadrupole lenses were designed and fabricated for a new breed of proton linear accelerator under development at the Los Alamos Scientific Laboratory. Four kinds of geometrical cross sections were investigated. The magnetic field gradients and multipole field harmonics up to n = 14 were measured with some compensated measuring coils for all the above models. A Hewlett-Packard Spectrum Analyzer 3580-A was used. Axial and transverse magnetic field surveys were performed with a Hall probe gaussmeter to determine the field gradients and the fringe field distribution. Quadrupole gradients in excess of 10 kG/cm were achieved using samarium-cobalt and certain geometries. These same quantities were calculated by a new computer code PAN-DIRA. The comparison between the calculations and the measurements showed excellent agreements on gradients and harmonic components. The field patterns were produced by PANDIRA. Among the above geometries, it turned out that the flat tip pole geometry is most promising. Grinding the tip decreases the harmonic contents rapidly compared with the slow decrease in the quadrupole field gradients. This is because the effective shape and the magnetization distribution approach to those of a hyperbolic quadrupole magnet. The hyperharmonic components of this geometry is less than 0.5% at r = 6 mm. The geometry offers an inexpensive and easy way of the fabrication and the gradient tuning. It satisfies the focal requirements and fits within the limited space of the structure.
Date: June 1, 1978
Creator: Saito, N.; Bush, E.D. & Swenson, D.A.
Partner: UNT Libraries Government Documents Department

Review of selected dynamic material control functions for international safeguards

Description: With the development of Dynamic Special Nuclear Material Accounting and Control systems used in nuclear manufacturing and reprocessing plants, there arises the question as to how these systems affect the IAEA inspection capabilities. The systems in being and under development provide information and control for a variety of purposes important to the plant operator, the safeguards purpose being one of them. This report attempts to judge the usefulness of these dynamic systems to the IAEA and have defined 12 functions that provide essential information to it. If the information acquired by these dynamic systems is to be useful to the IAEA, the inspectors must be able to independently verify it. Some suggestions are made as to how this might be done. But, even if it should not be possible to verify all the data, the availability to the IAEA of detailed, simultaneous, and plant-wide information would tend to inhibit a plant operator from attempting to generate a floating or fictitious inventory. Suggestions are made that might be helpful in the design of future software systems, an area which has proved to be fatally deficient in some systems and difficult in all.
Date: September 1, 1980
Creator: Lowry, L.L.
Partner: UNT Libraries Government Documents Department

Milliwatt Generator Project. Progress report, April-September 1980

Description: This formal biannual report covers the effort related to the Milliwatt Generator Project (MWG) carried out for the Department of Energy, Office of Military Applications, by the Los Alamos Scientific Laboratory (LASL). Most of the studies discussed here are of a continuing nature. Results and conclusions may change as the work continues. Published reference to the results cited in this report should not be made without the explicit permission of the person in charge of the work.
Date: January 1, 1981
Creator: Maraman, W.J. (comp.)
Partner: UNT Libraries Government Documents Department

Voltages in toroidal pinch experiments

Description: In toroidal experiments, such as Screw Pinches, Belt Pinches, and Reversed Field Pinches, with both toroidal and poloidal magnetic fields, quite complicated E-fields exist. For an appropriate design one should however, know what voltages occur between the various coils, the stabilizing shell, the plasma itself, the pumping stations, and diagnostic equipment. An attempt is made to give a systematic description of the voltages that develop between coils and objects placed inside them. Two types of coils are considered, one without an external return flux, analogous to the toroidal field coil; and one with external return flux, analogous to the poloidal field coil. Possible methods of grounding are discussed. The Appendix describes what voltages are to be expected in the ZT-40 Reversed-Field Pinch experiment under construction at the Los Alamos Scientific Laboratory.
Date: June 1, 1978
Creator: Van der Laan, P.C.T.
Partner: UNT Libraries Government Documents Department