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A photoemission investigation of compound semiconductor monodisperse clusters

Description: We have used synchrotron radiation photoemission to probe the valence and core level electronic structure of compound-semiconductor monodisperse clusters (nanocrystals). These clusters exhibited a 10% or less variation relative to the mean diameter and were attached to the metal substrates via alkane chains. Direct evidence of gap broadening due to size variation in CdS clusters was observed. The novel utilization of alkane chain attachment is the key to eliminating the otherwise debilitating p… more
Date: December 7, 1990
Creator: Tobin, J. G. (Lawrence Livermore National Lab., CA (USA)); Colvin, V. L. & Alivisatos, A. P. (California Univ., Berkeley, CA (USA))
Partner: UNT Libraries Government Documents Department
open access

Molecular cytogenetics using fluorescence in situ hybridization

Description: Fluorescence in situ hybridization (FISH) with chromosome-specific probes enables several new areas of cytogenetic investigation by allowing visual determination of the presence and normality of specific genetic sequences in single metaphase or interphase cells. in this approach, termed molecular cytogenetics, the genetic loci to be analyzed are made microscopically visible in single cells using in situ hybridization with nucleic acid probes specific to these loci. To accomplish this, the DNA i… more
Date: December 7, 1990
Creator: Gray, J.W.; Kuo, Wen-Lin; Lucas, J.; Pinkel, D.; Weier, H-U. & Yu, Loh-Chung.
Partner: UNT Libraries Government Documents Department
open access

A technique for shell compression measurements of laser fusion targets by neutron activation of a rubidium tracer

Description: At the Nova Laser, the activation of a rubidium tracer incorporated in the shell of ICF targets has become a standard diagnostic technique for measuring the compressed shell areal density {l angle}{rho}{Delta}R{r angle}. The isotope {sup 85}Rb is activated by 14 MeV implosion neutrons to produce the isomer {sup 84m}Rb(t{sub {1/2}} = 20.5 min) which is used to determine the shell {l angle}{rho}{Delta}R{r angle} while the radioactive isotope {sup 86}Rb(t{sub 1/2} = 18.8 d) is used to determine th… more
Date: December 7, 1990
Creator: Lane, S.M. & Nelson, M.B.
Partner: UNT Libraries Government Documents Department
open access

Effects of relativity of RTEX in collisions of U sup q+ with light targets

Description: We have calculated the resonant transfer and excitation cross sections in collisions of U{sup q+} (q = 82, 89, 90) ion with H{sub 2}, He and C in impulse approximation using the multi-configuration Dirac-Fock method. The calculations were carried out in intermediate coupling with configuration interaction. The quantum electrodynamic and finite nuclear size corrections were included in the calculations of transition energies. The Auger rates were calculated including the contributions from Coulo… more
Date: November 7, 1990
Creator: Chen, Mau Hsiung.
Partner: UNT Libraries Government Documents Department
open access

High power CW performance from a Ti:Sapphire laser and a single-pass amplifier

Description: Using two argon-ion lasers to pump a CW Ti:Sapphire laser we have demonstrated consistent high power (19 watts) operation with a low order spatial mode. Thermal lensing effects were controlled by enclosing the laser in a vacuum and cooling the rod with liquid nitrogen. Using this laser we also demonstrated a CW Ti:Sapphire amplifier with an efficiency of 20%. 5 refs., 5 figs.
Date: November 7, 1990
Creator: Erbert, G. V.; Bass, I. L.; Hackel, R. P.; Jenkins, S.; Kanz, K. V. & Paisner, J. A.
Partner: UNT Libraries Government Documents Department
open access

Experience with Position Sensitive Neutron Detectors at the Intense Pulsed Neutron Source

Description: At the Intense Pulsed Neutron Source (IPNS) pulses of protons accelerated in a synchrotron produce pulses of fast neutrons via the spallation process in an enriched uranium target. After moderation, the resulting pulses of slow neutrons are directed into beams which serve a variety of neutron scattering instruments. Currently there are thirteen neutron scattering instruments in operation or under development at IPNS, and six of these use position-sensitive neutron detectors (PSDs). These PSDs a… more
Date: May 7, 1990
Creator: Crawford, R. K.; Haumann, J. R.; Schultz, A. J.; Felcher, G. P.; Epperson, J. E.; Thiyagarajan, P. et al.
Partner: UNT Libraries Government Documents Department
open access

Accident analysis and safety review of DOE Category B reactors

Description: DOE is employing the principle of comparability with the NRC requirements to guide its safety program. Since the safety record of research reactors licensed by the NRC has been established and accepted, the comparison of DOE Orders applicable to DOE research reactors with the NRC regulations applicable to research reactors would identify strengths and weaknesses of the DOE Orders. The comparison was made in 14 general topics of safety which are labeled Areas of Safety Concerns. This paper focus… more
Date: August 7, 1990
Creator: Kimura, C. Y.
Partner: UNT Libraries Government Documents Department
open access

Inner-shell ionization of lithium-like chromium ions

Description: We have used high-resolution x-ray spectroscopy to investigate inner-shell ionization of Cr{sup 21+} ions by electron impact using the Electron Beam Ion Trap at Lawrence Livermore Laboratory. Our measurements indicate that inner-shell ionization enhances the intensity of the radiative transition 1s2s {sup 3}S{sub 1}{yields}1s{sup 2}{sup 1}S{sub 0}. 7 refs., 4 figs., 1 tab.
Date: September 7, 1990
Creator: Vogel, D. A.; Beiersdorfer, P.; Marrs, R. E.; Wong, K. L. & Zasadzinski, R.
Partner: UNT Libraries Government Documents Department
open access

Electron impact ionization cross section measurement of lithium-like barium ions

Description: The electron impact ionization cross section of Li-like Ba{sup 53+} has been measured at 22 keV using an electron beam ion trap. The measurement makes use of a novel technique, which is discussed in detail. We find a value somewhat higher than predicted by theory.
Date: September 7, 1990
Creator: Wong, K.; Beiersdorfer, P.; Vogel, D.A.; Marrs, R.E. (Lawrence Livermore National Lab., CA (USA)) & Levine, M. (Lawrence Berkeley Lab., CA (USA))
Partner: UNT Libraries Government Documents Department
open access

Measurement and Simulation of Whole Beam Brightness on the ETA-II (Experimental Test Accelerator-II) Linear Induction Accelerator

Description: Measurement of beam radius as a function of focusing strength of an upstream solenoidal field allows simultaneous determination of the beam energy, brightness and tilt of the phase space ellipse. On ETA-II beam radius has been measured by analyzing foil emitted Cherenkov light with a gated (5 ns) image intensified CCD camera. The beam energy measurement is corroborated with a spectrometer magnet and core brightness with a two hole emittance diagnostic. For a 6 MeV, 1.6 kA beam, the whole beam b… more
Date: August 7, 1990
Creator: Chen, Y. J.; CLark, J. C.; Paul, A. C.; Nexsen, W. E. & Turner, W. C.
Partner: UNT Libraries Government Documents Department
open access

Timing between streak cameras with a precision of 10 ps

Description: The laser beams irradiating a target at the Nova laser facility comprise a set of ten simultaneous events. Two streak cameras, whose resolutions are 40 ps, record the power history for each beam, five beams to a camera; their time bases are cross-timed with a fiducial pulse. Analysis of data recorded for target experiments conducted over a six month period show the precision for cross-timing signals between two streak cameras to be {plus minus}9 ps and for characterizing a single temporal featu… more
Date: December 7, 1990
Creator: Lerche, R. A.
Partner: UNT Libraries Government Documents Department
open access

Cumulative beam breakup of the ground-based-free-electron laser

Description: Strategies employed by the Ground-Based Free Electron Laser system to maintain beam stability in its rf linac against cumulative beam breakup will be described. These strategies include a proper choice of cavity shape and the use of staggered tuning. Simulations show that the growths of effective transverse emittance due to cumulative beam breakup can be limited to 10%. 4 refs., 5 figs., 1 tab.
Date: August 7, 1990
Creator: Chan, K. C. D. & Spalek, G.
Partner: UNT Libraries Government Documents Department
open access

Feed-forward compensation for transient beam loading of the 805 MHz debuncher for the Fermilab linac upgrade

Description: The expected momentum spread from the 400 MeV upgrade of the Fermilab linac is {plus minus}0.19% growing to about {plus minus}0.25% in 63 m of beam transport to the booster synchrotron. The desired injection value is about {plus minus}0.05%. An 805 MHz (h=1) debuncher is located 47 m downstream of the linac to reduce the momentum spread and the differences in mean energy between bunches. The beam pulse to the booster will vary from about 2--15 {mu}s at average current of 30--50 mA depending on … more
Date: September 7, 1990
Creator: MacLachlan, J. A.; Mills, F. E. & Owens, T.
Partner: UNT Libraries Government Documents Department
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