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Use of the Richardson-Lucy algorithm in analyzing positron annihilation spectroscopy dataYu, Dapeng. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.
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Positron annihilation spectroscopy studies of 6H N-type silicon carbide and Zn-doped P-type gallium antimonideLam, Chi-hung, January 2005 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
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The focusing of the HKU positron beam, and an extended design for incorporating secondary electron-positron annihilation lifetime spectroscopyKwan, Pui-ying, Rebecca. January 2006 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
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Detector noise reduction in positron doppler broadening related spectroscopy systems /Ching, Hei-man, Anita. January 2002 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 111-112).
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Investigation of the lifetime spectrum of monoenergetic positrons in silicon involving secondary electrons emission from a carbon foil as start signal, and positron annihilation spectroscopy studies of strontium titanteZhang, Yu, 張毓 January 2013 (has links)
A proposed design of the variable energy positron annihilation spectroscopy (VEPALS) system based on secondary electron (SE) emission from a thin carbon foil has been investigated practically. The SE yield and the positron transmission coefficient were investigated as a function of the positron beam energy, the annular electrode potentials, and the column lengths of the annular electrode. The positron lifetime spectra of single crystal p-type silicon(Si) sample under different annular electrode potentials were analyzed. The result gives a supposed annular electrode potential of 1.5 kV. In view of this, the positron lifetime spectra were measured under different positron beam energy by fixing the annular electrode potential. It can be seen that all the spectra have the main p-type Si bulk lifetime component of 234 ps occupying more than 60% intensities. The intensity of the 234 ps component reaches up to 84.5 ±1.3 % when the positron beam energy is 15 keV. Further, the origin of the satellite peaks in the positron lifetime spectra are also investigated. It has been shown that the satellite peaks is attributed to the overflowing positrons on the MCP detector.
The single crystal strontium titanate (STO) substrates after vacuum annealing treatment have been investigated in detail by several experimental techniques. The crystallization changes induced by the vacuum annealing were investigated by X-ray diffraction(XRD). Secondary phases were occurred after annealing treatment. The measured X-ray photoelectron spectroscopy (XPS) at O1s and C1s core levels were analyzed. The additional peaks after annealing are attributed to hydroxyl species, C-OH compounds, and carbonates. The variable energy Doppler broadening spectroscopy (VEDBS) and the traditional coincidence positron annihilation lifetime spectroscopy (PALS) were used to probe defects in STO samples. For long annealing time samples, the S parameters decrease below the reference level. The S-Wplot suggests that almost the same type of vacancy defects were induced during the annealing treatment. The positron lifetime results suggest that the main defects in annealed samples are oxygen monovacancies or divacancies and Sr-O vacancy complexes. The sample with annealing time of 110h has minimum positron effective diffusion length and maximum average lifetime, which is attributed to the increase of the vacancy-type defects during the long annealing treatment. / published_or_final_version / Physics / Master / Master of Philosophy
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Some mathematical studies in least square deconvolution of positron doppler broadening spectra using Huber regularizationWoo, Kee-tsz., 胡紀慈. January 2003 (has links)
published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy
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Some positron annihilation studies on highly doped and supersaturated N-type siliconHo, King-fung., 何競豐. January 2004 (has links)
published_or_final_version / abstract / toc / Physics / Doctoral / Doctor of Philosophy
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Detector noise reduction in positron doppler broadening related spectroscopy systems程曦敏, Ching, Hei-man, Anita. January 2002 (has links)
published_or_final_version / Physics / Master / Master of Philosophy
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Electric field distribution in metal/semi-insulating GaAs contacts investigated by positron lifetime techniqueShek, Yiu-fai., 石耀輝. January 1999 (has links)
published_or_final_version / Physics / Master / Master of Philosophy
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Positron annihilation spectroscopic studies of GAAS and INP related systems凌志聰, Ling, Chi-chung, Francis. January 1996 (has links)
published_or_final_version / Physics / Doctoral / Doctor of Philosophy
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