This report describes the development and testing of the upgraded Control and Monitoring (C&Mu) system for the TOFOR neutron spectrometer. TOFOR is currently performing plasma diagnostics for the JET experimental fusion reactor. The purpose of the C&Mu system is to enable monitoring of the amplitude dependent time delays of TOFOR. In order to perform this monitoring function the C&Mu system must comprise a pulsed light source with variable intensity and a reference time signal. In this work a reference time signal has been retrieved from a laser comprising a motorized polarizer. This has been accomplished by installing a photomultiplier tube and a beamsplitter cube. The beamsplitter cube splits the laser light into two parts and directs one part into the photomultiplier tube. The photomultiplier tube converts the light into an electrical reference time signal. A control program has been developed for the motorized polarizer, enabling the user to vary the intensity of the light over the interval from 0% to 100%. The C&Mu system has been performance tested and it was found that the time resolution of the system is about 0.1ns and the time stability of the system is about 0.12ns over 27 hours. The system is more than adequate to monitor variations in time delays at TOFOR of several nanoseconds, over a full JET day. The C&Mu system is ready to be installed on TOFOR.

This report describes simulations of observations with the near-infrared high-resolution spectrometer SIMPLE that is proposed to the ESO telescope E-ELT. We simulate M4 and G2 stars with transiting Earth-like planets and the goal is to distinguish spectral features originating from the atmosphere of the exoplanet. Noise levels of different magnitudes are added to the simulations and the minimal signal-to-noise required for detection of the atmosphere is estimated. Our conclusion is that detection of atmospheric features looks promising using this setup.

Simultaneous measurement of cross sections for pion production in pp recations at beam momenta of 805.2 MeV/c and 796.0 MeV/c with the TOF spectrometer at the COSY accelerator. / Simultane Bestimmung der Wirkungsquerschnitte von pionenproduzierenden pp-Reaktionen bei Strahlimpulsen von 805,2 MeV/c und 796,0 MeV/c mit dem TOF-Spektrometer am Beschleuniger COSY.

Les détecteurs et émetteurs travaillant dans la gamme dite Terahertz sont très coûteux et onctionnent généralement à basse température. Les Professeurs Dyakonov et Shur ont proposé en 1993 une théorie sur l'instabilité des ondes de plasma dans un gaz d'électrons bidimensionnel. Cette théorie énonce qu'un transistor peut fonctionner comme détecteur ou source Terahertz quand la longueur de grille est de taille nanométrique. Dans ce manuscrit, nous présentons une source de radiation Terahertz par un Transistor HEMT à base de l'hétérostructures GaN/AlGaN, (cohérente), accordable à température ambiante, relativement intense (0.1 NW), de taille nanométrique et peu coûteuse. En second lieu, nous proposons des détecteurs Terahertz basés sur la technologie GaN/AlGaN et InGaAs/InAlAs et accordables à température ambiante. Notre étude, d'intérêt pluridisciplinaire, vise à explorer les limites physiques et technologiques des performances des transistors HEMT sur l'Emission et la Détection de radiation Terahertz. L'estimation du NEP (Noise Equivalent Power) a également été réalisée. D'un point de vue fondamental, cette étude nous permettra de mieux connaître les propriétés de la détection et de l'émission par un gaz d'électrons bidimensionnel par le biais des ondes de plasma.

Thermo-stabilized lignin fibers from pH-fractionated softwood kraft lignin were carbonized to various temperatures during thermomechanical analysis (TMA) under static and increasing load and different rates of heating. The aim was to optimize the carbonization process to obtain suitable carbon fiber material with good mechanical strength potential (high tensile strength and high E-modulus). The carbon fibers were therefore mainly evaluated of mechanical strength in Dia-Stron uniaxial tensile testing. In addition, chemical composition, in terms of functional groups, and elemental (atomic) composition was studied in Fourier transform infrared spectroscopy (FTIR) and in energy-dispersive X-ray spectroscopy (EDS), respectively. The structure of carbon fibers was imaged in scanning electron microscope (SEM) and light microscopy. Thermogravimetrical analysis was performed on thermo-stabilized lignin fibers to evaluate the loss of mass and to calculate the stress-changes and diameter-changes that occur during carbonization. The TMA-analysis of the deformation showed, for thermo-stabilized lignin fibers, a characteristic behavior of contraction during carbonization. Carbonization temperatures above 1000°C seemed most efficient in terms of E-modulus and tensile strength whereas rate of heating did not matter considerably. The E-modulus for the fibers was improved significantly by slowly increasing the load during the carbonization. The tensile strength remained however unchanged. The FTIR-analysis indicated that many functional groups, mainly oxygen containing, dissociate from the lignin polymers during carbonization. The EDS supported this by showing that the oxygen content decreased. Accordingly, the relative carbon content increased passively to around 90% at 1000°C. Aromatic structures in the carbon fibers are thought to contribute to the mechanical strength and are likely formed during the carbonization. However, the FTIR result showed no evident signs that aromatic structures had been formed, possible due to some difficulties with the KBr-method. In the SEM and light microscopy imaging one could observe that porous formations on the surface of the fibers increased as the temperature increased in the carbonization. These formations may have affected the mechanical strength of the carbon fibers, mainly tensile strength. The carbonization process was optimized in the sense that any heating rate can be used. No restriction in production speed exists. The carbonization should be run to at least 1000°C to achieve maximum mechanical strength, both in E-modulus and tensile strength. To improve the E-modulus further, a slowly increasing load can be applied to the lignin fibers during carbonization. The earlier the force is applied, to counteract the lignin fiber contraction that occurs (namely around 300°C), the better. However, in terms of mechanical performance, the lignin carbon fibers are still far from practical use in the industry.

This research deals with equivalent dose rate (EDR) in the ground level air caused by gamma radiation. Weighting factor for gamma radiation is equal one, so EDR in the ground air is identical absorbed ionic radiation dose. Highways A6 Kaunas-Zarasai and A11 Panevėžys-Šiauliai-Palanga were investigated. In this research the main parameters determining the level of equivalent dose rate in the ground air by the Lithuanian highways have been defined and analyzed. The objective of this research is to measure EDR in the ground air by the Lithuanian highways and compare to adequate average regional and with reference to modulation values evaluate variation reasons. In the expeditions EDR in the ground air was measured in winter and in summer. Samples of soil and asphalt were examined with gamma spectrometer and analyze presented. There was determined the dependence of EDR in the ground air from soil composition, floral or snow cover and distance to the asphalt cover. Cosmic radiation impact on EDR formation is equal to all locations. Natural origin radionuclides in soil gamma radiation have the main influence to EDR formation in the ground air. Modeling program VISIPLAN was used to define impact of radionuclides radiation in asphalt cover to EDR formation in the roadside zone. Modeling program InterRAS was used to define EDR in the ground air formation from gamma radiation of radionuclide in soil.

Due to recent progress in theory and the growing number of physical realizations, low-dimensional quantum magnets continue to receive a considerable amount of attention. They serve as model systems for investigating numerous physical phenomena in spin systems with cooperative ground states, including the field-induced evolution of the ground-state properties and the corresponding rearrangement of their low-energy excitation spectra. This work is devoted to systematic studies of recently synthesized low-dimensional quantum spin systems by means of multi-frequency high-field electron spin resonance (ESR) investigations. In the spin- 1/2 chain compound (C6H9N2)CuCl3 [known as (6MAP)CuCl3] the striking incompatibility with a simple uniform S = 1/2 Heisenberg chain model employed previously is revealed. The observed ESR mode is explained in terms of a recently developed theory, revealing the important role of the alternation and next-nearest-neighbor interactions in this compound. The excitations spectrum in copper pyrimidine dinitrate [PM·Cu(NO3)2(H2O)2]n, an S = 1/2 antiferromagnetic chain material with alternating g-tensor and Dzyaloshinskii-Moriya interaction, is probed in magnetic fields up to 63 T. To study the high field behavior of the field-induced energy gap in this material, a multi-frequency pulsed-field ESR spectrometer is built. Pronounced changes in the frequency-field dependence of the magnetic excitations are observed in the vicinity of the saturation field, B ∼ Bs = 48.5 T. ESR results clearly indicate a transition from the soliton-breather to a spin-polarized state with magnons as elementary excitations. Experimental data are compared with results of density matrix renormalization group calculations; excellent agreement is found. ESR studies of the spin-ladder material (C5H12N)2CuBr4 (known as BPCB) completes the determination of the full spin Hamiltonian of this compound. ESR results provide a direct evidence for a pronounced anisotropy in this compound, that is in contrast to fully isotropic spin-ladder model employed previously for BPCB. Our observations can be of particular importance for describing the rich temperature-field phase diagram of this material. The frequency-field diagram of magnetic excitations in the quasi-two dimensional S = 1/2 compound [Cu(C4H4N2)2(HF2)]PF6 in the AFM-ordered state is studied. The AFM gap is observed directly. Using high-field magnetization and ESR results, parameters of the effective spin-Hamiltonian (exchange interaction, anisotropy and g-factor) are obtained and compared with those estimated from thermodynamic properties of this compound.

The detonation of a radiological dispersion device (RDD) may result in a situation where many individuals are exposed to contamination due to the inhalation of radioactive materials. Assessments of contamination may need to be performed by emergency response personnel in order to triage the potentially exposed public. The feasibility of using readily available standard 2x2-inch sodium-iodide detectors to determine the committed effective dose to a patient following the inhalation of a radionuclide has been investigated. The 2x2-NaI(Tl) detector was modeled using the Monte Carlo simulation code, MCNP-5, and was validated via a series of experimental benchmark measurements using a polymethyl methacrylate (PMMA) slab phantom. Such validation was essential in reproducing an accurate detector response. Upon verification of the detector model, six anthropomorphic phantoms, based on the MIRD-V phantoms, were modeled with nuclides distributed to simulate inhaled contamination. The nuclides assessed included Am-241, Co-60, Cs-137, I-131, and Ir-192. Detectors were placed at four positions on the phantoms: anterior right torso, posterior right torso, anterior neck, and lateral left thigh. The detected count-rate varied with respect to detector position, and the optimal detector location was determined on the body. The triage threshold for contamination was set at an action level of 250-mSv of intake. Time dependent biokinetic modeling was employed to determine the source distribution and activity in the body as a function of post-inhalation time. The detector response was determined as a function of count-rate per becquerel of activity at initial intake. This was converted to count-rate per 250-mSv intake for triage use by first responders operating the detector to facilitate triage decisions of contamination level. A set of procedure sheets for use by first responders was compiled for each of the phantoms and nuclides investigated.

Ce travail porte sur la réalisation d'un microspectromètre SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) incluant des compteurs de photons SNSPD (Superconducting Nanowire Single Photon Detector). Il met en œuvre un interféromètre intégré à guide d'onde en arête bouclé, en SiN, sous lequel sont disposés 24 nanofils supraconducteurs SNSPD en NbN échantillonnant les interférences au pas de 160nm, à une longueur d'onde centrée sur 1.55µm. La conception, l'étude des composantes optique et électronique, la fabrication et la caractérisation à 4.2K sont décrites, jusqu'à la mise en évidence d'une modulation de puissance lumineuse dans le guide conformément à la formation attendue d'interférences. Le SWIFTS-SNSPD constitue le premier dispositif optoélectronique supraconducteur à part entière, doublement intégré. Sa capacité unique d'échantillonnage direct de franges d'interférences ouvre de nombreuses perspectives, pour des applications allant de l'astrophysique aux télécoms. / This work presents the realization of a SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) micro-spectrometer with SNSPD (Superconducting Nanowire Single Photon Detector) photon counters. The device features an integrated interferometer made of a SiN loop ridge-waveguide, with an array of 24 NbN-nanowire SNSPD underneath that samples at a 160nm period the interferogram of a laser light, at a wavelength centred on 1.55µm. The conception, preliminary studies of integrated optics and electronics, fabrication and characterization at 4.2K of the final device are described, in particular the observation of the detected signal modulation in the waveguide in agreement with the expected interference formation. The SWIFTS-SNSPD constitutes the first stand-alone, fully integrated superconducting optoelectronic device. Its unique capability of direct sampling of light interferogram opens numerous perspectives, with possible applications ranging from astrophysics to telecommunications.

The title of the thesis: The Identification of Substances in Real Samples Using Portable Raman Spectrometer The portable Raman spectrometer Ahura First Defender is a device designated for identifying unrecognized solid and liquid substances. The aim of this diploma thesis was to test the efficiency of the portable Raman spectrometer First Defender and to draw up a draft of the methodology for its manipulation. The objects of the investigation were the accuracy of results and collection of findings coming out of measuring tests using the device mentioned above. The introduction part briefly describes problems of chemical monitoring within Fire Rescue Service of the Czech Republic. As a partly solution of the problems could be the use of the portable spectrometer First Defender. Further are described problems of sampling and possibilities of sample detection through means of chemical reconnaissance. As next, there is described the device itself including the principle of Raman effect that allows the device to identify unrecognized solid and liquid chemical substances. The practical part explains the procedure and the way of applied measuring tests when using the device. The results are summarized in charts and the percentage of successful performed tests analyzed in charts. Findings concerning the manipulation with the device, methods for sample modification and the influence of sample matrix on the identification of selected chemicals in observed samples are introduced in the discussion. Professional knowledge and experience were used to draw up guidelines for the identification of substances in real samples conceived as general informational source describing procedures, rules, and recommendations. Upon all outcomes and findings, there was confirmed the hypothesis of greatly beneficial using Raman spectrometer in Fire Protection Units when identifying unknown substances at places of intervention at the end of the thesis.