Coherent scatter measurements have previously shown promise as a method for detection and identification of materials. However, the time required for measurements is rather long and the computer power required to analyse the data can be quite considerable. A multiple angle coherent scatter system has been designed and built to assess the feasibility of using this technique as an alternative to a single angle coherent scatter system. An application of detecting the presence of explosives within baggage to go on board aircraft was used to test the multiple angle system. A cadmium zinc telluride detector was found to be suitable to be used with the multiple angle system. A model of the system was used to determine the number of angles required and to determine the characteristics of the collimator that would be suitable with this detector. The objective of this work was to develop a simple method of analysing the data yielded from multiple angle coherent scatter system. This has been achieved by plotting the scatter signatures in the form of energy-angle diagrams and using these plots to determine the optimum energy windows to be used with each scatter angle. Samples of 4 mm of Semtex and 6 mm of SX2 were detected with 0% false alarm rate at 100% detection rate with a single energy window centred at a planar spacing of 3.3 Å. A detector array with collimation has been built to fit within the dimensions of an existing baggage scanner. This caused an increase in the scatter volume and hence the explosive sample constituted a smaller part of it. The results were that the false alarm rate was higher than for the initial system, at 37.5% It is concluded that the multiple angle detection of coherent scatter signatures is a promising method for the detection of explosives and that it could be used for several other applications in the future.

The thesis deals with the NQR spectroscopy, which is one of the modern non-destructive measurement and diagnostic methods for the characterization of various materials. It is using a quadrupole moment - a property of atomic nuclei of certain isotopes. A method of nuclear quadrupole resonance (NQR) is in principle very similar to nuclear magnetic resonance (NMR). Thesis in the theoretical part analyse the principles of NMR and NQR, describes the possible use of this method to detect for example explosives, drugs, and other chemicals. In the following chapters are analysed the key parameters of NQR spectrometer and the principle of the chosen measurement method. The practical part deals with the individual components of NQR spectrometer, the design of possible improvements and programming of the measuring sequence. In the final chapter are processed the measurements of the submitted samples.

Spectroscopic techniques allow for studies of materials and organisms on the atomic and molecular level. Examples of such techniques are nuclear magnetic resonance (NMR) spectroscopy—one of the principal techniques to obtain physical, chemical, electronic and structural information about molecules—and magnetic resonance imaging (MRI)—an important medical imaging technique for, e.g., visualization of the internal structure of the human body. The less well-known spectroscopic technique of nuclear quadrupole resonance (NQR) is related to NMR and MRI but with the difference that no external magnetic field is needed. NQR has found applications in, e.g., detection of explosives and narcotics. The first part of this thesis is focused on detection and identification of solid and liquid explosives using both NQR and NMR data. Methods allowing for uncertainties in the assumed signal amplitudes are proposed, as well as methods for estimation of model parameters that allow for non-uniform sampling of the data. The second part treats two medical applications. Firstly, new, fast methods for parameter estimation in MRI data are presented. MRI can be used for, e.g., the diagnosis of anomalies in the skin or in the brain. The presented methods allow for a significant decrease in computational complexity without loss in performance. Secondly, the estimation of blood flow velo-city using medical ultrasound scanners is addressed. Information about anomalies in the blood flow dynamics is an important tool for the diagnosis of, for example, stenosis and atherosclerosis. The presented methods make no assumption on the sampling schemes, allowing for duplex mode transmissions where B-mode images are interleaved with the Doppler emissions.

The thesis deals with RF spectroscopic methods, which are applicable for the detection of hazardous substances such as explosives or drugs. Particular attention is focused on promising method of nuclear quadrupole resonance. Abroad this method has recently been applied in the detection of energetic materials in hazardous locations. The cornerstone of the nuclear quadrupole resonance is to evaluate the interaction between electromagnetic radiation, in the range of medium to very short waves, and the researched substance. Observed parameter are the resonant frequencies of the substance. Spectral analysis of signal is used for their evaluation. Resonant frequencies are always typical for the crystalline structure, therefore every explosive or drug is clearly identifiable by this method.