Search Results

Advanced search parameters have been applied.
open access

Alpha-Decay Studies in the Heavy-Element Region

Description: Using primarily a 75-cm radius of curvature 60 deg symmetrical electromagnetic analyzer, a study of the complexity of the following alpha spectra was made: Es/sup 253/, Cf/sup 246/, Cm/sup 244/, Am/sup 243/, Pu/sup 236,242/, Pa/sup 231/ , Th/sup 227,230/, Ac/sup 225/, At/sup 209/ and Po/sup 206/. An investigation of the gamma rays associated with the following isotopes was also madei /sup 236/, and Pa/sup 231/. Decay schemes have been suggested for most of the isotopes included in this study. T… more
Date: July 1, 1956
Creator: Hummel, J. P.
Partner: UNT Libraries Government Documents Department
open access

Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

Description: It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations… more
Date: July 20, 2011
Creator: Perkins, M. P.; Ong, M. M.; Brown, C. G. & Speer, R. D.
Partner: UNT Libraries Government Documents Department
open access

Asymmetric antiproton debuncher: No bad mixing, more good mixing

Description: An asymmetric lattice for the Fermilab Antiproton Debuncher is designed. The lattice has zero mixing between the pickups and the kickers (bad mixing) while the mixing in the rest of the machine (good mixing) can be varied (even during the operation of the machine) in order to optimize the stochastic cooling. As an example, a lattice with zero bad mixing and twice the good mixing is presented. The betatron cooling rate in this lattice is twice its present value.
Date: July 1, 1994
Creator: Visnjic, V.
Partner: UNT Libraries Government Documents Department
open access

Axions in Astrophysics and Cosmology

Description: Axion models often have a spontaneously broken exact discrete symmetry. In that case, they have discretely degenerate vacua and hence domain walls. The properties of the domain walls, the cosmological catastrophe they produce and the ways in which this catastrophe may be avoided are explained. Cosmology and astrophysics provide arguments that imply the axion decay constant should lie in the range 10/sup 8/ GeV less than or equal to f/sub a/ less than or equal to 10/sup 12/ GeV. Reasons are give… more
Date: July 1, 1984
Creator: Sikivie, P.
Partner: UNT Libraries Government Documents Department
open access

Beam dynamics enhancement due to accelerating field symmetrization in the BNL/SLAC/UCLA 1.6 cell S-band photocathode RF gun

Description: A 1.6 cell photocathode S-Band gun developed by the BNL/SLAC/UCLA collaboration is now in operation at the Brookhaven Accelerator Test Facility (ATF). One of the main features of this RF gun is the symmetrization of the RF coupling iris with an identical vacuum pumping port located in the full cell. The effects of the asymmetry caused by the RF coupling iris were experimentally investigated by positioning a metallic plunger at the back wall of the vacuum port iris. The higher order modes produc… more
Date: July 1997
Creator: Palmer, D. T.; Miller, R. H.; Wang, X. J. & Ben-Zvi, Ilan
Partner: UNT Libraries Government Documents Department
open access

Beam dynamics in SLC

Description: Beam dynamics issues affect many different aspects of the SLC performance. This paper concentrates on the multi-particle beam dynamics in the linac and the associated limitations that are imposed on the overall SLC performance. The beam behavior in the presence of strong wakefields has been studied in order to optimize the performance and to predict the expected emittances in high performance linacs. Emittance measurements and simulations are presented for the SLAC linac and are compared in det… more
Date: July 1, 1997
Creator: Assmann, R. W.
Partner: UNT Libraries Government Documents Department
open access

Computer Modeling of Electromagnetic Edge Containment in Twin-Roll Casting

Description: This paper presents modeling studies of magnetohydrodynamics (MHD) analysis in twin-roll casting. Argonne National Laboratory (ANL) and Inland Steel Company have worked together to develop a 3-D computer model that can predict eddy currents, fluid flows, and liquid metal containment for an electromagnetic (EM) edge containment device. This mathematical model can greatly shorten casting research on the use of EM fields for liquid metal containment and control. It can also optimize the existing c… more
Date: July 1, 1998
Creator: Chang, F. C.; Turner, L. R.; Hull, J. R.; Wang, Y. H. & Blazek, K. E.
Partner: UNT Libraries Government Documents Department
open access

A CYLINDRICALLY SYMMETRIC UNIAXIAL PML MAXWELL SOLVER FOR TRANSIENT ATMOSPHERIC ELECTRICITY SIMULATIONS

Description: The recent interest in high altitude discharges known as red sprites, blue jets, and elves has stimulated the modeling of transient atmospheric electricity. The modeling of these high altitude discharges require an initiating cloud-to-ground or intracloud lightning event in order to pre-condition the electric field between the cloud tops and the ionosphere. In this short paper we describe a finite difference time domain (FDTD) numerical solution of Maxwell's equations based on the Yee (Yee 1966… more
Date: July 1, 2001
Creator: SYMBALISTY, E. M.
Partner: UNT Libraries Government Documents Department
open access

Direct time-domain techniques for transient radiation and scattering. [Introduction to transient electromagnetics]

Description: A tutorial introduction to transient electromagnetics, focusing on direct time-domain techniques, is presented. Physical, mathematical, numerical, and experimental aspects of time-domain methods, with emphasis on wire objects excited as antennas or scatters are examined. Numerous computed examples illustrate the characteristics of direct time-domain procedures, especially where they may offer advantages over procedures in the more familiar frequency domain. These advantages include greater solu… more
Date: July 1, 1976
Creator: Miller, E. K. & Landt, J. A.
Partner: UNT Libraries Government Documents Department
open access

Dispersion in the presence of strong transverse wakefields

Description: To minimize emittance growth in a long linac, it is necessary to control the wakefields by correcting the beam orbit excursions. In addition, the particle energy is made to vary along the length of the bunch to introduce a damping, known as the BNS damping, to the beam break-up effect. In this paper, the authors use a two-particle model to examine the relative magnitudes of the various orbit and dispersion functions involved. The results are applied to calculate the effect of a closed orbit bum… more
Date: July 1, 1997
Creator: Assmann, R. & Chao, A.
Partner: UNT Libraries Government Documents Department
open access

Dynamic Model for Electromagnetic Field and Heating Patterns in Loaded Cylindrical Cavities

Description: An analytical solution for the electromagnetic fields in a cylindrical cavity, partially filled with a cylindrical dielectric has been recently reported. A program based on this solution has been developed and combined with the authors` previous program for heat transfer analysis. The new software has been used to simulate the dynamic temperature profiles of microwave heating and to investigate the role of electromagnetic field in heating uniformity and stability. The effects of cavity mode, ca… more
Date: July 1, 1995
Creator: Tian, Y. L.; Black, W. M.; Sa`adaldin, H. S.; Ahmad, I. & Silberglitt, R.
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic field analysis of septum magnet for APS positron accumulator ring

Description: This report consists of three parts. The first part describes a numerical analysis method for the electromagnetic field analysis of a septum magnet. A novel improvement to the treatment of exciting currents in the time-domain is proposed. The second part discusses numerical predictions of the electromagnetic characteristics of the APS PAR septum. The time variations of stray field and eddy currents are shown for three magnet designs. The last part explores how decreasing the septum material con… more
Date: July 1, 1995
Creator: Yokoi, Toshiaki & Turner, L. R.
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic field effects on cells of the immune system: The role of calcium signalling

Description: During the past decade considerable evidence has accumulated demonstrating the exposures of cells of the immune system to relatively weak extremely-low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes which might be relevant to in-vivo immune activity. However, knowledge about the underlying biological mechanisms by which weak fields induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca{sup 2+} regulated activity is in… more
Date: July 1, 1991
Creator: Walleczek, J.
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic field measurements on a mm-wave linear accelerator

Description: Field strength measurements for the determination of the R/Q of a mm-wave, 50-MeV electron linear accelerator using perturbational techniques are described. The perturbation is achieved using optical fibers coated with a thin metallic film to form a hollow cylinder. The perturbational form factors for such a geometry are approximated using several simple analytical expressions which are compared to a finite difference calculation as well as experimental results on a known cavity.
Date: July 1, 1994
Creator: Matthews, P.; Kang, Y.; Berenc, T.; Kustom, R.; Willke, T. & Feinerman, A.
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic fields in cased borehole

Description: Borehole electromagnetic (EM) measurements, using fiberglass-cased boreholes, have proven useful in oil field reservoir characterization and process monitoring (Wilt et al., 1995). It has been presumed that these measurements would be impossible in steel-cased wells due to the very large EM attenuation and phase shifts. Recent laboratory and field studies have indicated that detection of EM signals through steel casing should be possible at low frequencies, and that these data provide a reasona… more
Date: July 20, 2001
Creator: Lee, Ki Ha; Kim, Hee Joon & Uchida, Toshihiro
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic Penetration Through Narrow Slots in Conducting Surfaces and Coupling to Structures on the Shadow Side

Description: Electromagnetic field penetration through a curved narrow slot in a planar conducting surface and coupling to a curved, loaded thin wire on the shadow side are determined in the time domain (TD) and the frequency domain (FD) by integral equation methods. Coupled integral equations are derived and solved numerically for the equivalent magnetic current in the slot and the electric current on the wire, from which the field that penetrates the slotted surface is determined. One employs a piecewise … more
Date: July 1, 1990
Creator: Reed, Erik K. & Butler, Chalmers M.
Partner: UNT Libraries Government Documents Department
open access

Electroseismic characterization of lithology and fluid type in the shallow subsurface. Final report, January 15, 1995--January 14, 1997

Description: The U.S. Department of Energy funded the M.I.T. Earth Resources Laboratory to investigate electroseismic phenomena. Because electroseismic phenomena in fluid-saturated porous media provide geophysicists with a unique opportunity to detect a seismic-wave-generated flow of pore fluid with respect to the porous matrix. The term {open_quotes}electroseismic{close_quotes} describes phenomena in which a seismic wave induces an electrical field or causes radiation of an electromagnetic wave. Electrosei… more
Date: July 1, 1997
Creator: Haartsen, Matthijs W.; Mikhailov, Oleg V.; Queen, John H.; Toksouz, M. Nafi & Zhu, Zhenya
Partner: UNT Libraries Government Documents Department
open access

Energy stability in recirculating, energy-recovering linacs

Description: Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents … more
Date: July 1, 1996
Creator: Merminga, L.; Bisognano, J.J. & Delayen, J.R.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen