Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3041. Adviser: Mats Selen. Includes bibliographical references (leaves 259-263) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6887. Adviser: Alfred Huebler. Includes bibliographical references (leaves 73-76) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2005. / Source: Dissertation Abstracts International, Volume: 66-04, Section: B, page: 2112. Adviser: John L. Challifour. "Title from dissertation home page (viewed Nov. 22, 2006)."

Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2005. / Source: Dissertation Abstracts International, Volume: 66-03, Section: B, page: 1508. Adviser: Jay X. Tang. "Title from dissertation home page (viewed Nov. 2, 2006)."

Thesis (Ph. D.)--Indiana University, Dept. of History and Philosophy of Science, 2006. / "Title from dissertation home page (viewed July 16, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: A, page: 3842. Advisers: Jordi Cat; Michael Dickson.

Optical and electrical techniques are used to characterise deep- levels in silicon that could have applications in extrinsic silicon thermal imagers. The concentration of indium in indium-doped silicon substrates is estimated from Hall-effect and capacitance-voltage measurements together with chemical analysis and infra-red absorption. Junction space-charge measurements on diode structures are used to give information on the thermal emission rate, photoionisation cross-section, and enthalpy values of impurities and radiation-induced defects in silicon. The responsivity, noise and detectivity of indium-doped silicon detectors are measured and found to be in very good agreement with calculated values of these quantities. A model for the responsivity is developed which explains the general features of the experimental responsivity results in terms of capture and emission processes from acceptor levels. Finally, the use of the punch-through technique to produce a compact monolithic extrinsic silicon thermal imager is described and results of its low temperature operation are given.

High pressure has been used to study electrical transport properties of GaAs, InSb and In[1-x]Ga[x]As[y]P[1-y], grown lattice matched to InP. The pressure dependence of the r[c1] effective mass has been determined in InSb at ~ 160 K to ~ 14 kbar and in GaAs at ~ 300 K to ~ 22 kbar, using measurements of the magnetophonon effect in the transverse magnetoresistance. The pressure coefficients obtained are: InSb (160 K): dm*/dP = 6.2 + 0.2 % kbar[-1] GaAs (300 K): dm*/dP = 0.63 + 0.05 % kbar[-1] Good agreement is acquired between the observed m* variation in InSb and simple three band k. p. theory. For GaAs reasonable agreement is obtained using the simpler k. p theory but the agreement becomes worse as a more refined theory is considered which takes account of higher lying minima. The electron mobility in high purity InSb has been studied at room temperature as a function of hydrostatic pressure to 15 kbar. The mobility, which reduced by ~ 50% to 15 kbar, is shown to be dominantly controlled by polar optical scattering and electron scattering by holes. The direct energy gap pressure coefficient for InSb is measured to be: dEo/dP = (14.6 + 0.2) x 10[-3] eV kbar -1 The electron and hole mobilities in n-and p-type samples of the quaternary alloy In1-xGaxAsyP1-y, grown lattice-matched to, semi-insulating Fe doped (100) InP substrates have been studied as a function of hydrostatic pressure to 16 kbar, at room temperature. The electron mobility reduced by ~ 20% to 15 kbar for samples with y = 0.5, while the hole mobility reduced by approximately a fifth of the electron mobility values to 15 kbar. These results confirmed the presence of alloy scattering. The temperature dependence of the Gunn threshold in GaAs has been investigated, with Monte Carlo calculations giving reasonable agreement to experimental results. The temperature coefficient obtained is 1/Ip (300 K) dl p/dT = - 2. 4 x 10[-3] K[-1] which is independent of carrier concentration, and 1/Vp(300 K) dVp/ dT is positive and decreases with increasing carrier concentration. The results support a r-L-X ordering of the band structure of GaAs at atmospheric pressure.

This project was undertaken to measure the relative numbers of -ve pions captured onto carbon, nitrogen and oxygen in a number of mostly organic compounds. The results have been used to investigate the validity of the Fermi Teller law. Dosimetry calculations, currently being used to plan -ve pion radiotherapy treatment, are based on the predictions of this law. Results from this experiment show it to be incorrect for organic molecules. The results have also been used to guide the development of a previously existing molecular model of pion capture. A cascade calculation has been undertaken in order to gain further insight into the pionic capture and cascade processes and to determine whether or not certain processes, neglected for the purposes of the capture ratio calculation, were truly negligible.

Comparisons between the thin and thick target methods of measuring proton-induced K X-ray production cross-sections have been made. It was concluded that the thin target technique is superior. Cross-sections for the production of K X-rays from thin targets of selected elements in the range Z = 22-34 have been measured with absolute uncertainties of +/- 5 % for the case of irradiation with light ions (Z ≤ 2) of energy 1-3 MeV. K shell ionization cross-sections have been deduced from these measurements and a modification of the Semi-Classical Approximation fitted to the resulting data. Fitted values for the ionization cross-sections for protons have been generated for all targets with Z = 18-50; uncertainties being as low as +/- 5 % in the region Z = 22-34. The value of these results for use in particle-induced X-ray emission (PIXE) analysis and in comparisons between the various theories of inner shell ionization is discussed. A detailed description is given of the apparatus and experimental techniques; especially the methods of measuring ion beam fluence, X-ray detection efficiency and target mass thickness. For each of these cases, significant advances over the more commonly used methods are reported. The principles, history and present status of PIXE analysis are outlined and comparison made with other methods of producing characteristic X-rays. The technique has been applied to the study of time-resolved deposits of air particulate pollution. Details are given of the air sampling technique and the application of PIXE and electron microprobe X-ray analysis to the characterization of these samples. Analyses of a widely varying selection of other types of sample were performed and conclusions drawn on the suitability of the technique for these cases. Finally, conclusions are drawn on the achievements of the work and suggestions for future studies are given.

This study is concerned with the development of laser anemometers based on digital autocorrelation of the scattered-light signal and intended for wind-tunnel applications at the Royal Aircraft Establishment. The optical arrangements are of the Doppler-difference type. The theory of photodetection and photon statistics is first reviewed and the analytical relationship established between the Doppler-difference signal and its autocorrelation function for both laminar and turbulent flows. It is shown that interpretation of the data is greatly facilitated if the optical geometry meets certain simple criteria. When operating in backscatter on large facilities, integration of the signals from a number of successive scatterers is generally necessary, and it is shown how under these circumstances the data can be related by a Fourier transform to the probability distribution of the velocity in the measurement region. The design of data-reduction algorithms capable of fast and accurate extraction of this probability distribution from the composite autocorrelation function is then discussed. The properties of laser beams of particular relevance to the design of the optical system are considered and a simple technique for the measurement of beam diameter and divergence is described. Methods for the determination of fringe spacing, the basic experimental parameter in Doppler-difference arrangements, are assessed and compared. Frequency-modulation devices for use in highly turbulent flows are briefly reviewed and a technique is described by means of which large and variable frequency offsets can be obtained without deviation of the transmitted beam. A number of experiments carried out with photon correlation anemometers on subsonic and supersonic flows under a wide range of turbulence conditions are described. The results of these experiments are presented and discussed. Further improvements which may be incorporated in future systems are considered.