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in subjects: "Backscattering"

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Negative ion production by backscattering from alkali-metal surfaces bombarded by ions of hydrogen and deuterium

Measurements have been made of the total backscattered D/sup -/ and H/sup -/ yields from thick, clean targets of Cs, Rb, K, Na, and Li, bombarded with H/sub 2//sup +/, H/sub 3//sup +/, D/sub 2//sup +/, and D/sub 3//sup +/ with incident energies from 0.15 to 4.0 keV/nucleus. All of the measurements were made at background pressures less than 10/sup -9/ Torr and the alkali-metal targets were evaporated onto a cold substrate (T = 77K) in situ to assure thick, uncontaminated targets. Measurements o… more

Date: March 1, 1980

Creator: Schneider, P.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Enhanced ion backscattering near 180/sup 0/ scattering angles in the two-atom scattering model. [Ion scattering from solids]

An analytical two-atom scattering model has been developed to treat the recent discovery of the enhancement near 180/sup 0/ of Rutherford backscattering yields from disordered solids. In contrast to conventional calculations of Rutherford backscattering that treat scattering from a single atom only (the backscattering atom), the present model includes the interaction of a second atom lying between the target surface and the backscattering atom. The projectile ion makes a glancing collision with… more

Date: August 1, 1982

Creator: Oen, O.S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Model for H/sup -/ and D/sup -/ production by hydrogen backscattering

The Marlowe Monte-Carlo backscattering code has been used to calculate particle reflection coefficients and energy distributions for H, D incident upon Li, K, Ni, Cu, Mo, Ag, Cs, Hf, W, Pt, and U surfaces. The backscattered energy and angular distributions are combined with a model for formation and survival probabilities for H/sup -/, D/sup -/ leaving the surface. A least-squares fit of experimental measurements of H/sup -/ yields from the composite surface, Cs/Cu, has been used to obtain two … more

Date: May 27, 1980

Creator: Hiskes, J.R. & Schneider, P.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Determination of surface oxide compositions on Alloy 600 using Rutherford backscattering

The surface composition of oxides formed on Alloy 600 under conditions similar to those in the primary side of PWR heat exchangers has been studied as a function of potential using Rutherford backscattering and proton inelastic scattering. Electropolished samples of Alloy 600 were exposed at several potentials to a solution of 0.18M H/sub 3/BO/sub 3/(2000 ppM B) with 0.28M LiOH (1.4 ppM Li) at 300/sup 0/C for 450 hours. The potentials relative to an internal hydrogen electrode ranged from -.09 … more

Date: January 1, 1984

Creator: Hanson, A. L.; Isaacs, H. S. & Kraner, H. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Determination of light elements in amalgam restorations. [Dental amalgam]

Rutherford backscattering has been used to measure the major elemental compositions in the near-surface regions of freshly prepared and used samples of dental amalgam. A depletion from bulk stoichiometry of the major elements, which indicates an accumulation of lighter elements on the surface of the materials, has been observed. Increases in the F, Na, Cl, P, O, C, and N concentrations between freshly prepared samples and used samples were measured by observation of gamma rays produced by proto… more

Date: January 1, 1982

Creator: Hanson, A. L.; Jones, K. W.; Kraner, H. W.; Osborne, J. W. & Nelson, G. V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Benchmark field study of deep neutron penetration

A unique benchmark neutron field has been established at the Lawrence Livermore National Laboratory (LLNL) to study deep penetration neutron transport. At LLNL, a tandem accelerator is used to generate a monoenergetic neutron source that permits investigation of deep neutron penetration under conditions that are virtually ideal to model, namely the transport of mono-energetic neutrons through a single material in a simple geometry. General features of the Lawrence Tandem (LATAN) benchmark field… more

Date: June 10, 1991

Creator: Morgan, J. F.; Sale, K. (Lawrence Livermore National Lab., CA (USA) ); Gold, R.; Roberts, J. H. & Preston, C. C. (Metrology Control Corp., Richland, WA (USA) )

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heating by the Raman instability

Computer simulations are presented of the reflection and heating due to stimulated Raman backscatter of intense laser light in large regions of underdense plasma. The heated electron distribution is found to be approximately a Maxwellian of temperature (m/sub e//2)v/sub p//sup 2/, where v/sub p/ is the phase velocity of the electron plasma wave. A simple model of the reflection is presented. Raman may cause a pre-heat problem with large laser fusion reactor targets.

Date: April 11, 1980

Creator: Estabrook, K.G. & Kruer, W.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nondestructive evaluation of the oxidation and strength of the Fort Saint Vrain HTGR support block

Non-destructive detection of changes in the strength of graphite support structures in a HTGR appears to be feasible using sonic velocity measurements where access for through transmission is possible. Therefore, future HTGR designs should consider providing such access. Where access is not available, strength changes can be correlated with oxidation profiles in the support member. These oxidation profiles can be determined non-destructively by a combination of eddy current measurements to dete… more

Date: April 1, 1982

Creator: Tingey, G. L.; Posakony, G. J.; Morgan, W. C.; Prince, J. M.; Hill, R. W. & Lessor, D. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Non-linear theory of laser-plasma interactions

Research progress on each of the following areas is briefly described: (1) optical ray retracing of Brillouin backscattering from a nonisothermal plasma; (2) electromagnetic oscillating two-stream instability of laser radiation; (3) second harmonic generation of upper hybrid radiation in a plasma; (4) nonlinear scattering of upper hybrid laser radiation by electron Bernstein modes in a plasma; and (5) destructive collisions of supersonic solitons. (MOW)

Date: January 1, 1980

Creator: Liu, C.S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Spallation target-moderator-reflector studies at the Weapons Neutron Research facility. [800-MeV p]

Basic neutronics data, initiated by 800-MeV proton spallation reactions, are important to spallation neutron source development and electronuclear fuel production. Angle-dependent and energy-dependent neutron production cross sections, energy-dependent and total neutron yields, thermal and epithermal neutron surface and beam fluxes, and fertile-to-fissile conversion ratios are being measured. The measurements are being done at the Weapons Neutron Research facility on a variety of targets and ta… more

Date: January 1, 1980

Creator: Russell, G. J.; Gilmore, J. S.; Prael, S. D.; Robinson, H. & Howe, S. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some analytical solutions to the two atom blocking model

The two-atom blocking model with thermal displacements was reinvestigated, and some new analytical results were found. For Coulomb scattering, an exact solution for the blocking pattern is found which depends on only two parameters. For scattering from a Moliere potential, a similar parameterization produces a nearly universal set of curves. The results should be useful in analyzing data of ion backscattering experiments that measure crystal surface relaxation. 4 figures.

Date: January 1, 1977

Creator: Oen, O S

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Characterization of the TEXTOR plasma edge using deposition probe techniques

Carbon and single crystal silicon passive deposition probes were used to measure the characteristics of the plasma edge region of the TEXTOR tokamak. Analysis of the probes was done by Rutherford backscattering for impurities and nuclear reaction analysis and elastic recoil detection for hydrogen isotopes. Plasma fluxes and energies in the edge were measured using probe techniques. The principal impurities in the plasma edge were determined and their behavior as a function of time and position … more

Date: October 1, 1983

Creator: Zuhr, R.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Kinematics of Compton backscattering x-ray source for angiography

Calculations of X-Ray production rates, energy spread, and spectrum of Compton-backscattered photons from a Free Electron Laser on an electron beam in a low energy (136-MeV) compact (8.5-m circumference) storage ring indicate that an X-Ray intensity of 34.6 10{sup 7} X-Ray photons per 0.5-mm {times} 0.5-mm pixel for Coronary Angiography near the 33.169-keV iodine K-absorption edge can be achieved in a 4-msec pulse within a scattering cone of 1-mrad half angle. This intensity, at 10-m from the p… more

Date: May 1, 1992

Creator: Blumberg, L.N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Laser annealing of ion implanted CZ silicon for solar cell junction formation. Quarterly report No. 1

A project to evaluate the merits of large spot size pulsed laser annealing of ion implanted silicon wafers for junction formation on solar cells is described. A Q-switched Nd:Glass laser system is used operating in the 1064 (regular) and 532 (with frequency doubler) nm wavelengths. The laser output is in excess of 30 joules with a 20 to 50 ns pulse duration. Material used in this investigation is 3-inch diameter CZ silicon, P-type 0.014 inches thick, 10..cap omega..-cm resistivity, <100> … more

Date: July 1, 1980

Creator: Katzeff, J. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Work function dependence of surface produced H/sup -/ in the presence of a plasma

The maximum H/sup -/ flux from a netatively biased converter cathode occurs at the work function minimum. A cesiated hydrogen plasma produces a partially-cesiated surface at the converter. The cesium coverage can be be controlled by the cesium partial pressure, the bias on the converter and the plasma density, while the work function of the converter surface is measured by the photo-electric effect, using a bright light source and a series of filters. The angular dependence is measured by rotat… more

Date: November 1, 1983

Creator: Wada, M.; Pyle, R. V. & Stearns, J. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron energy and charge albedos - calorimetric measurement vs Monte Carlo theory

A new calorimetric method has been employed to obtain saturated electron energy albedos for Be, C, Al, Ti, Mo, Ta, U, and UO/sub 2/ over the range of incident energies from 0.1 to 1.0 MeV. The technique was so designed to permit the simultaneous measurement of saturated charge albedos. In the cases of C, Al, Ta, and U the measurements were extended down to about 0.025 MeV. The angle of incidence was varied from 0/sup 0/ (normal) to 75/sup 0/ in steps of 15/sup 0/, with selected measurements at … more

Date: November 1, 1981

Creator: Lockwood, G. J.; Ruggles, L. E.; Miller, G. H. & Halbleib, J. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Exchange interpretation of anomalous back angle heavy ion elastic scattering

Anomalous back angle oscillations in the angular distributions obtained in the elastic scattering of /sup 16/O + /sup 28/Si and /sup 12/C + /sup 28/Si have been interpreted in terms of an elastic cluster transfer comparable to that observed in other heavy ion reactions. The calculations appear to at least qualitatively explain the data with respect to the existence and phase of the back angle oscillations. The results indicate that an exchange mechanism may play an important role in the oscilla… more

Date: October 1, 1977

Creator: Zisman, M. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Support of the NATO Effects Task Group by Los Alamos National Laboratory

A method is outlined for measuring the transient attenuation of optical fibers and/or cables exposed to a pulse of radiation (gamma rays, x-rays, electrons, protons, neutrons, etc). It can be employed to determine the level of radiation-induced attenuation (in units of dB/km as a function of time) produced in single-mode or multi-mode optical fibers, in either cabled or uncabled form, due to pulsed exposure to radiation. Co{sup 60} radiation-induced attenuation is measured by optical time domai… more

Date: January 1, 1991

Creator: Lyons, P. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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MOESSBAUER EFFECT USING BACKSCATTER GEOMETRY AS APPLIED TO NONDESTRUCTIVE TESTING.

No Description Available.

Date: January 1, 1969

Creator: Ord, R.N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Pinellas plant ion accelerator facility: an apparatus for low-energy ion scattering and nuclear reaction analysis

The General Electric Neutron Devices Department (GEND) Ion Accelerator Facility first came to being in the Chemistry Laboratory of the Department of Energy (DOE) Pinellas Plant in 1975, with the installation of an Accelerator Inc. Model 200 HP Ion Implanter. The machine was originally used for ion implantation work; and since the machine's relocation in 1979 from the main plant building, the facility has been heavily involved in target assessment and material analysis work. An ultrahigh vacuum … more

Date: January 1, 1983

Creator: Malbrough, D.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Elastic and inelastic surface effects on ion penetration and the resulting sputtering and backscattering

The computer code ITMC (Ion Transport in Materials and Compounds) has been developed to study in detail the transport of charged particles in solid materials and surface related phenomena such as sputtered atoms and backscattered ions. The code is based on Monte Carlo methods to follow the path and the damage produced by the charged particles in three dimension as they slow down in target materials. Single-element targets as well as alloys with possible different surface and bulk compositions o… more

Date: January 1, 1985

Creator: Hassanein, A. M. & Smith, D. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Direct methods for seismic profiling. Final report

A coordinated research program in inverse problems was concluded. The program evolved from formulation to analytical solution to implemented computer algorithms. There were two main lines of research in this program: a velocity inversion method, with application to seismic exploration, and a physical optics inverse scattering method for reflector mapping, with application to nondestructive evaluation. In each case, computer algorithms based on the theoretical results were tested on real or test… more

Date: December 12, 1979

Creator: Bleistein, N.; Cohen, J. K. & Hagin, F. G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Radar Location Equipment Development Program: Phase I

The work described in this report represents the first phase of a planned three-phase project designed to develop a radar system for monitoring waste canisters stored in a thick layer of bedded salt at the Waste Isolation Pilot Plant near Carlsbad, New Mexico. The canisters will be contained in holes drilled into the floor of the underground waste storage facility. It is hoped that these measurements can be made to accuracies of +-5 cm and +-2/sup 0/, respectively. The initial phase of this pro… more

Date: June 1, 1985

Creator: Sandness, G.A. & Davis, K.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The coupling of stimulated Raman and Brillouin scattering in a plasma

The observation of an anti-Stokes satellite in the spectrum of light backscattered from a CO{sub 2} laser plasma is reported. Its origin is found to be Thomson scattering of the incident light from a counterpropagating mode-coupled plasma wave. The parent electron and ion waves in the mode-coupling process were driven by stimulated Raman and Brillouin backscattering. The parent and daughter plasma waves were detected by ruby laser Thomson scattering. A computer simulation modeling the experimen… more

Date: September 19, 1988

Creator: Umstadter, D.; Mori, W.B. & Joshi, C. (Lawrence Livermore National Lab., CA (USA))

Item Type: Report

Partner: UNT Libraries Government Documents Department