The ANL experiment for a wake field accelerator using an rf structure (open access)

The ANL experiment for a wake field accelerator using an rf structure

Experiments are planned at ANL to study a new accelerating concept that has been developed during the last few years named the WAKEATRON. This requires a very special, simple configuration of the beams and of the rf structure involved. The basic concepts are explained. Like most proposed experimental work, this too was initiated by a considerable amount of computational work, both analytical and numerical, on which we would like to report. We will then describe details of the planned experiments we will carry out at ANL to check some of our predictions for this concept. These experiments concentrate on beam and cavity geometry applicable to the Wakeatron.
Date: August 27, 1986
Creator: Ruggiero, A. G.; Schoessow, P. & Simpson, J.
System: The UNT Digital Library
Antiproton-hydrogen atom rearrangement-annihilation cross section (open access)

Antiproton-hydrogen atom rearrangement-annihilation cross section

For antiproton energies of several eV or less, annihilation in matter occurs through atomic rearrangement processes in which the antiproton becomes bound to a nucleus prior to annihilation. Existing calculations of the antiproton-hydrogen atom rearrangement cross section are semiclassical and employ the Born-Oppenheimer approximation. They also employ various arguments in regard to the behavior of the system when the Born-Oppenheimer approximation breaks down at small antiproton-proton separations. These arguments indicate that rearrangement is essentially irreversible. In the present study, a detailed investigation was made of the antiproton-hydrogen atom system when the Born-Oppenheimer approximation breaks down. The results of this study indicate that the previous arguments were approximately correct, but that there is a significant probability for rearrangement reversing prior to annihilation. This probability is estimated to be about 20%. 8 refs., 4 figs., 2 tabs.
Date: August 22, 1986
Creator: Morgan, D.L. Jr.
System: The UNT Digital Library
Application of Synchrotron Radiation to X-Ray Fluorescence Analysis of Trace Elements (open access)

Application of Synchrotron Radiation to X-Ray Fluorescence Analysis of Trace Elements

The development of synchrotron radiation x-ray sources has provided the means to greatly extend the capabilities of x-ray fluorescence analysis for determinations of trace element concentrations. A brief description of synchrotron radiation properties provides a background for a discussion of the improved detection limits compared to existing x-ray fluorescence techniques. Calculated detection limits for x-ray microprobes with micrometer spatial resolutions are described and compared with experimental results beginning to appear from a number of laboratories. The current activities and future plans for a dedicated x-ray microprobe beam line at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory are presented.
Date: August 1, 1986
Creator: Gordon, B. M.; Jones, K. W. & Hanson, A. L.
System: The UNT Digital Library
Applications of the MEVVA high current metal ion source (open access)

Applications of the MEVVA high current metal ion source

A new kind of ion source has been developed in which a metal vapor vacuum arc (MEVVA) is used to produce the plasma from which the ion beam is extracted. The novel and exciting feature of this source is the very high metal ion beam current attainable. A total ion beam current of over 1 Ampere has been extracted from the embodiment of the concept that we're presently using, and this is not a limit of the method. The source was developed to upgrade the uranium ion beam intensity of the Bevatron, LBL's heavy ion synchrotron, for basic nuclear physics research. Other important applications include its use within the Heavy Ion Fusion research effort; for ion implantation; and for other basic research uses. In this paper the source is described briefly, its performance outlined, and its poential and limitations for a variety of applications is discussed.
Date: August 1, 1986
Creator: Brown, I.G.
System: The UNT Digital Library
An asteroseismology explorer (open access)

An asteroseismology explorer

In response to a NASA opportunity, a proposal has been made to study the concept of an Asteroseismology Explorer (ASE). The goal of the ASE would be to measure solar-like oscillations on many (perhaps hundreds) of stars during a 1-year mission, including many members of open clusters. We describe this proposal's observational goals, a strawman technical approach, and likely scientific rewards. 5 refs.
Date: August 11, 1986
Creator: Brown, T. M. & Cox, A. N.
System: The UNT Digital Library
Commercial oxide paints as coatings for SiGe thermoelectric materials (open access)

Commercial oxide paints as coatings for SiGe thermoelectric materials

Silicon-germanium alloys are used as thermoelectric materials for radioisotope thermoelectric generators. One problem is the loss of the alloy by sublimation. In the Unicouple, sublimation was minimized by a Si/sub 3/N/sub 4/ coating. In the Multicouple design the application of Si/sub 3/N/sub 4/ coatings which is done at high temperature is not practical. Suppression of sublimation in the Multicouple design is presently accomplished by applying glass coatings. The difficulties encountered with the glass coatings are associated with the poor adherence of the coatings. In the present study, commercial oxide points (mainly ZrO/sub 2/) which have low thermal expansion coefficients are used as coating materials. No spalling from the surface of the coated sample occurred in 1506 hours at 1080/sup 0/C in vacuum, and sublimation was reduced significantly. Zirconium silicate was observed on the surface by x-ray diffraction.
Date: August 25, 1986
Creator: Amano, T.; Beaudry, B. J. & Gschneidner, K. A., Jr.
System: The UNT Digital Library
Compact Torus plasma ring accelerator: a new type driver for inertial confinement fusion (open access)

Compact Torus plasma ring accelerator: a new type driver for inertial confinement fusion

We discuss the acceleration of magnetically-confined plasma rings to provide a driver for ICF. The acceleration of plasma rings is predicted to be efficient and following focusing, to generate ion-bombardment power in the range 10/sup 15/ to 10/sup 16/ W/cm/sup 2/ at a total deposition energy of multimegajoules. The simplicity of plasma ring accelerator suggests that a 5 MJ (on target) driver would cost in the range 1 to 5 $/joule. First experimental tests of the accelerator are described.
Date: August 22, 1986
Creator: Hartman, C. W.; Eddleman, J. L.; Hammer, J. H. & Meeker, D. L.
System: The UNT Digital Library
Complex fragment emission at low and high excitation energy (open access)

Complex fragment emission at low and high excitation energy

Complex fragment emission has been certified as a compound nucleus process at low energies. An extension of the measurements to heavy ion reactions up to 50 MeV/u shows that most complex fragments are emitted by highly excited compound nuclei formed in incomplete fusion reactions. 12 refs., 26 figs.
Date: August 1, 1986
Creator: Moretto, Luciano G.
System: The UNT Digital Library
Conceptual Design of A 1-2 GeV Synchroton Radiation Source (open access)

Conceptual Design of A 1-2 GeV Synchroton Radiation Source

A description is presented of the conceptual design of the Lawrence Berkeley Laboratory 1-2 GeV Synchrotron Radiation Source, which is designed to produce ultraviolet and soft x-ray radiation. The facility consists of an injection system (linac plus booster synchrotron), a low emittance storage ring optimized at 1.5 GeV, several insertion devices (wigglers and undulators) located in the storage ring straight sections, and beam lines from the insertion devices and bending magnets. Storage ring performance is analyzed in terms of lattice, collective instabilities and beam lifetime. The injection system and its performance are discussed. Spectral characteristics of the radiation are presented.
Date: August 1, 1986
Creator: St, The 1-2 GeV Synchrotron Radiation Source Design
System: The UNT Digital Library
Construction and testing of the Mirror Fusion Test Facility magnets (open access)

Construction and testing of the Mirror Fusion Test Facility magnets

This paper describes the construction and testing of the Mirror Fusion Test Facility superconducting magnet set. Construction of the first Yin Yang magnet was started in 1978. And although this particular magnet was later modified, the final construction of these magnets was not completed until 1985. When completed these 42 magnets weighed over 1200 tonnes and had a maximum stored energy of approximately 1200 MJ at full field. Together with power supplies, controls and liquid nitrogen radiation shields the cost of the fabrication of this system was over $100M. General Dynamics/Convair Division was responsible for the system design and the fabrication of 20 of the magnets. This contract was the largest single procurement action at the Lawrence Livermore National Laboratory. During the PACE acceptance tests, the 26 major magnets were operated at full field for more than 24 hours while other MFTF subsystems were tested. From all of the data, the magnets operated to the performance specifications. For physics operation in the future, additional helium and nitrogen leak checking and repair will be necessary. In this report we will discuss the operation and testing of the MFTF Magnet System, the world's largest superconducting magnet set built to date. The topics …
Date: August 1, 1986
Creator: Kozman, T.; Shimer, D.; VanSant, J. & Zbasnik, J.
System: The UNT Digital Library
Controlling laboratory conditions and preventing the problem: The health physicist's viewpoint (open access)

Controlling laboratory conditions and preventing the problem: The health physicist's viewpoint

This document contains the text of a presentation on safety problems associated with the use of analytical x-ray equipment. General comments on the positive and negative aspects of both administrative and hardware controls preceded a more detailed discussion of specific examples in each area. Also included were comments on machine safety by the manufacturer and suggestions for further reading on the safe use of x-ray diffraction and spectrometry equipment. (TEM)
Date: August 1, 1986
Creator: de Castro, T.M.
System: The UNT Digital Library
Convective heat transport in geothermal systems (open access)

Convective heat transport in geothermal systems

Most geothermal systems under exploitation for direct use or electrical power production are of the hydrothermal type, where heat is transferred essentially by convection in the reservoir, conduction being secondary. In geothermal systems, buoyancy effects are generally important, but often the fluid and heat flow patterns are largely controlled by geologic features (e.g., faults, fractures, continuity of layers) and location of recharge and discharge zones. During exploitation, these flow patterns can drastically change in response to pressure and temperature declines, and changes in recharge/discharge patterns. Convective circulation models of several geothermal systems, before and after start of fluid production, are described, with emphasis on different characteristics of the systems and the effects of exploitation on their evolution. Convective heat transport in geothermal fields is discussed, taking into consideration (1) major geologic features; (2) temperature-dependent rock and fluid properties; (3) fracture- versus porous-medium characteristics; (4) single- versus two-phase reservoir systems; and (5) the presence of noncondensible gases.
Date: August 1, 1986
Creator: Lippmann, M.J. & Bodvarsson, G.S.
System: The UNT Digital Library
Damping rings for achieving ultra-small electron beam emittance (open access)

Damping rings for achieving ultra-small electron beam emittance

Production of low emittance beams at injection is examined via a computer simulation program. Two machines were studied using the simulation program, both of which were assumed circular with no straight sections, with radii of 100 and 1000 meters. The program accounts for first order beam transport, damping from energy loss due to synchrotron radiation, excitation from the quantum nature of the radiation, beam excitation due to the presence of gas molecules in the beam pipe, magnet errors, beam growth due to intrabeam scattering, and the effect of wakefields induced in the rf cavity. The machines considered are found to be feasible and to have small emittances. Intrabeam scattering is found to be the dominant process affecting the beam emittance. (LEW)
Date: August 1, 1986
Creator: Hand, L. N. & Vinson, M. J.
System: The UNT Digital Library
Design and characterization for absolute x-ray spectrometry in the 100-10,000 eV region (open access)

Design and characterization for absolute x-ray spectrometry in the 100-10,000 eV region

Reviewed here are the design and characterization procedures used in our program for developing absolute x-ray spectrometry in the 100 to 10,000 eV region. Described are the selection and experimental calibration of the x-ray filters, mirror momochromators, crystal/multilayer analyzers, and the photographic (time integrating) and photoelectric (time resolving) position-sensitive detectors. Analytical response functions have been derived that characterize the energy dependence of the mirror and crystal/multilayer reflectivities and of the photographic film and photocathode sensitivities. These response functions permit rapid, small-computer reduction of the experimental spectra to absolute spectra (measured in photons per stearadian from the source for radiative transitions at indicated photon energies). Our x-ray spectrographic systems are being applied to the diagnostics of pulsed, high temperature plasma sources in laser fusion and x-ray laser research. 15 refs., 27 figs.
Date: August 1, 1986
Creator: Henke, B.L.
System: The UNT Digital Library
Diffuse x-ray scattering studies of n and e/sup -/-irradiated Ni and dilute Ni alloys (open access)

Diffuse x-ray scattering studies of n and e/sup -/-irradiated Ni and dilute Ni alloys

Pure Ni and dilute NiSi and NiGe alloys were irradiated at 6 K with either fast neutrons or 3 MeV electrons. The resulting defect structures were studied using diffuse x-ray scattering methods after different annealing treatments. For both types of irradiation of pure Ni, large interstitial and vacancy dislocation loops developed on annealing. In contrast, interstitial agglomerates in a NiSi/sub .01/ alloy contained no more than approx. =10 interstitials, and few vacancy loops were observed. Complete recovery was observed at lower temperatures in the alloy. Similar results were found for NiGe/sub .01/, although larger interstitial clusters were observed. The results are discussed within the model for the trapping reactions developed previously to explain the results of e/sup -/ irradiation of these same alloys.
Date: August 1, 1986
Creator: Averback, R. S. & Ehrhart, P.
System: The UNT Digital Library
Does the photino decay (open access)

Does the photino decay

The stability of the lightest superpartner is a crucial aspect of many experimental searches for supersymmetry and of supersymmetric dark matter candidates. It is shown that R parity may occur in operators of dimension four or less as an accidental consequence of an exact Z/sub N/ symmetry. In this case the lightest superpartner can decay via higher dimension operators. The lifetime depends on the scale of the new physics responsible for the non-renormalizable operators; it could be anywhere in the region 10/sup -20/ seconds to 10/sup +20/ seconds. Explicit examples are given. 12 refs.
Date: August 29, 1986
Creator: Hall, L.J.
System: The UNT Digital Library
Dosimetry of x-ray beams: The measure of the problem (open access)

Dosimetry of x-ray beams: The measure of the problem

This document contains the text of an oral presentation on dosimetry of analytical x-ray equipment presented at the Denver X-Ray Conference. Included are discussions of sources of background radiation, exposure limits from occupational sources, and the relationship of these sources to the high dose source of x-rays found in analytical machines. The mathematical basis of x-ray dosimetry is reviewed in preparation for more detailed notes on personnel dosimetry and the selection of the most appropriate dosimeter for a specific application. The presentation concludes with a discussion common to previous x-ray equipment accidents. 2 refs. (TEM)
Date: August 1, 1986
Creator: de Castro, T.M.
System: The UNT Digital Library
Dynamic Devices: Pickups and Pickers (open access)

Dynamic Devices: Pickups and Pickers

A large proportion of the dynamic devices used to interact with the charged-particle beams in accelerators or storage rings can be classified as pickups or kickers. These devices act through time-varying electromagnetic fields either to extract information about the particle's motion or to effect a change in that motion. A given configuration of electrodes may be used either as a pickup or as a kicker; that duality will be addressed in this paper. An example of a simple electrode is the loop antenna, which may be made in the shape of an electrical stripline at the side of a beam chamber. This electrode.picks up a signal from the beam current by intercepting time-varying magnetic flux and image charges of the beam. One can also understand that the difference signal from two such striplines placed on opposite sides of the beam will give information on the beam's transverse position. This same electrode, if externally excited as a kicker, can produce transverse forces through its magnetic field acting on moving charges; and its electric fields in the direction of the particle motion produce its effects as a longitudinal kicker. Electrodes for a particular application call for response over a particular range of …
Date: August 1, 1986
Creator: Lambertson, G.
System: The UNT Digital Library
Effects of wigglers and undulators on beam dynamics (open access)

Effects of wigglers and undulators on beam dynamics

Synchrotron light facilities are making ever increasing use of wigglers and undulators, to the extent that these devices are becoming a significant part of the beam optical system of the storage ring itself. This paper presents a theoretical formulation for investigating the effect of wigglers and undulators on beam dynamics in the approximation that the wiggler parameter, K, divided by ..gamma.. is a small number and that the number of wiggler periods in one device is large. In addition to the linear forces which must be taken into account when tuning and matching the ring, nonlinear stop bends are created, with even orders more serious than odd orders. Some numerical examples are given for devices similar to those proposed for the 1-2 GeV Synchrotron Radiation Source at Lawrence Berkeley Laboratory.
Date: August 1, 1986
Creator: Smith, L.
System: The UNT Digital Library
Electron impact ionization of heavy ions: some surprises (open access)

Electron impact ionization of heavy ions: some surprises

This paper reports the results of calculations of electron impact ionization cross sections for a variety of heavy ions using a distorted wave Born-exchange approximation. The target is described by a Hartree-Fock wavefunction. The scattering matrix element is represented by a triple partial wave expansion over incident, scattered, and ejected (originally bound) continuum states. These partial waves are computed in the potentials associated with the initial target (incident and scattered waves) and the residual ion (ejected waves). A Gauss integration was performed over the distribution of energy between the two final state continuum electrons. For ionization of closed d- and f-subshells, the ejected f-waves were computed in frozen-core term-dependent Hartree-Fock potentials, which include the strong repulsive contribution in singlet terms which arises from the interaction of an excited orbital with an almost closed shell. Ground state correlation was included in some calculations of ionization of d/sup 10/ subshells.
Date: August 22, 1986
Creator: Younger, S.M.
System: The UNT Digital Library
Enthalpies of combustion of four N-phenylmethylene benzenamine N-oxide derivatives, of N-phenylmethylene benzenamine, and of trans-diphenyldiazene N-oxide: the dissociation enthalpy of the (N-O) bonds (open access)

Enthalpies of combustion of four N-phenylmethylene benzenamine N-oxide derivatives, of N-phenylmethylene benzenamine, and of trans-diphenyldiazene N-oxide: the dissociation enthalpy of the (N-O) bonds

Article on enthalpies of combustion of four N-phenylmethylene benzenamine N-oxide derivatives, of N-phenylmethylene benzenamine, and of trans-diphenyldiazene N-oxide and the dissociation enthalpy of the (N-O) bonds.
Date: August 1, 1986
Creator: Kirchner, James J.; Acree, William E. (William Eugene); Pilcher, Geoffrey & Shaofeng, Li
System: The UNT Digital Library
Evaluation of the IRAD flexible probe sonic extensometer (open access)

Evaluation of the IRAD flexible probe sonic extensometer

Evaluation of the IRAD sonic extensometer was initiated with an electronic-circuit analysis which indicated an accuracy of +-0.001 in. (0.025 mm). Readings from two sonic probes consistently were low by 2% for distances between magnetic anchors, but were accurate to +-0.002 and +-0.003 in. (0.051 and 0.076 mm) for small displacements. Although a series of high explosive tests subjected magnetic anchors to peak accelerations of from 2100 g to 32,000 g the anchors generally did not experience detectable damage. Sonic probe readings exhibited a sensitivity to temperature changes with two of the four segments monitored exceeding the correction factor cited by the manufacturer.
Date: August 1, 1986
Creator: Glenn, H. D.; Patrick, W. C.; Rector, N. L. & Butler, L. S.
System: The UNT Digital Library
Evolution of Cepheids with pulsationally-driven mass loss (open access)

Evolution of Cepheids with pulsationally-driven mass loss

Models have been run of intermediate mass stars (5, 6, 7, and 8 M/sub theta/ with Y = 0.28, Z = 0.02) with pulsationally-driven mass loss occurring in the Cepheid instability strip. The new /sup 12/C(..cap alpha..,..gamma..)/sup 16/O rates of Caughlan were used. The enhanced rate extends the tip of the blue loop, allowing the 5 and 6 M/sub theta/ models to re-enter the Cepheid strip, unlike the models calculated using the old rates (Becker, 1981). An investigation was conducted to see if mass loss during the Cepheid stage could redden the tip of the blue loop sufficiently to place it inside the instability strip, thereby ''trapping'' the star, and allowing it to lose mass for a period of time significantly longer than the normal crossing time. Results show that this mechanism does in fact work for a 7 M/sub theta/ star with mass loss rates as low as approx.5 x 10/sup -7/ M/sub theta/ yr/sup -1/. Observations of P-Cygni profiles in Cepheids indicate that this rate is not unreasonable. This behavior acts to reduce the discrepancy between the evolutionary and pulsation-derived masses for Cepheids. Another consequence is that the rates of period change are decreased, bringing them into better …
Date: August 1, 1986
Creator: Brunish, W. M. & Willson, L. A.
System: The UNT Digital Library
Evolution of Variable Stars (open access)

Evolution of Variable Stars

Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as ..beta.. Cephei stars, delta Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab.
Date: August 1, 1986
Creator: Becker, S. A.
System: The UNT Digital Library