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PHYSICS DIVISION ANNUAL PROGRESS REPORT FOR PERIOD ENDING FEBRUARY 10, 1961

Description: Results are discussed for investigations of: elastic scattering of bound nuclei; center-of-mass energy in Overhauser's self-consistent field with giant density fluctuations; the distorted-wave theory of direct nuclear reactions; an excitation method for an optical maser; energy spectra for BETA decay of He/sup 6/; electron shake-off following He/sup 6/ decay; neutrons from He/sup 3/ bombardment of Be/sup 9/, Ci/sup 1//sup 3/, and Li/sup 7/; total neutron cross section of Pb/sup 2//sup 0//sup 8/; neutron total cross sections for selenium isotopes at 4 to 50 kev; statistical parameters of nuclei from kev neutron total and capture cross sections; high-resolution total neutron cross sections of Am/ sup 2//sup 4//sup 1/ and Np/sup 2//sup 3//sup 7/; Breit-Wigner resonances; neutron radiative capture at 200 to 6000 ev; gamma spectra from 30-kev neutron capture; gamma - gamma angular correlations in Xe/sup 1//sup 3//sup 2/; Coulomb excitation of levels in Se/sup 7//sup 7/; Mossbauer method of HFS splitting of Au/ sup 1//sup 9//sup 7/ alloys wlth iron, cobalt, and nickel; magnetic ordering in rare-earth intermetallic compounds; frequency calibrations of prism spectrometers and spectral slit-width measurements; vapor-phase infrared absorption spectra of HfF/sub 4/, TiF/sub 4/, and ZrF/sub 4/; polarized deuteron sources; pulse characteristics of fast phototubes; properties of semiconductor detectors; and the response of silicon detectors to fission fragments. (B.O.G.)
Date: May 1, 1961
Partner: UNT Libraries Government Documents Department

STANDARD CLEARANCE HOLE SIZES

Description: Reprinted with revisions from SCTM-133-56(16). Abridged version published in Prod. Eng. May 12, 1958. This study establishes standard clearance hole sizes for the common screw fastener sizes, positional tolerances and assembly applications. These clearance hole sizes are expressed as standard drill sizes in the tables. In arriving at these drill sizes, consideration was given to the fact that drills cut oversize and that deviations in the size of drilled holes must be expected even under ideal operating conditions. (auth)
Date: June 1, 1958
Creator: Millard, C I
Partner: UNT Libraries Government Documents Department

PHYSICS DIVISION SUMMARY REPORT, JUNE 1963. Annual Review

Description: Research progress in experimental and theoretical nuclear physics, theoretical high-energy physics, and extranuclear properties of matter is summarized. Accelerator operations and irnprovements are reported, and a list of publications is included. Separate abstracts have been prepared for the nine sections of the report. (D.C.W.)
Date: October 31, 1963
Partner: UNT Libraries Government Documents Department

Broad-band Light Emission From Ion Implanted Silicon Nanocrystals Via Plasmonic and Non-plasmonic Effects for Optoelectronics

Description: Broad band light emission ranging from the ultraviolet (UV) to the near infrared (NIR) has been observed from silicon nanoparticles fabricated using low energy (30-45 keV) metal and non-metal ion implantation with a fluence of 5*1015 ions/cm2 in crystalline Si(100). It is found from a systematic study of the annealing carried out at certain temperatures that the spectral characteristics remains unchanged except for the enhancement of light emission intensity due to annealing. The annealing results in nucleation of metal nanoclusters in the vicinity of Si nanoparticles which enhances the emission intensity. Structural and optical characterization demonstrate that the emission originates from both highly localized defect bound excitons at the Si/Sio2 interface, as well as surface and interface traps associated with the increased surface area of the Si nanocrystals. The emission in the UV is due to interband transitions from localized excitonic states at the interface of Si/SiO2 or from the surface of Si nanocrystals. The radiative efficiency of the UV emission from the Si nanoparticles can be modified by the localized surface plasmon (LSP) interaction induced by the nucleation of silver nanoparticles with controlled annealing of the samples. The UV emission from Si nanoclusters are coupled resonantly to the LSP modes. The non-resonant emission can be enhanced by electrostatic-image charge effects. The emission in the UV (~3.3 eV) region can also be significantly enhanced by electrostatic image charge effects induced by Au nanoparticles. The UV emission from Si nanoclusters, in this case, can be coupled without LSP resonance. The recombination of carriers in Si bound excitons is mediated by transverse optical phonons due to the polarization of the surface bound exciton complex. The low energy side of emission spectrum at low temperature is dominated by 1st and 2nd order phonon replicas. Broad band emission ranging from the UV to the ...
Date: December 2012
Creator: Singh, Akhilesh K.
Partner: UNT Libraries