The purpose of this thesis is to assemble an HPGe detector intended to be used in a mass experiment during the autumn of 2018. After assembly, the detector will be characterized and a shielding, consisting of approximately two tons of lead, will be assembled around the detector. Different modules will be tested to find the optimal energy resolution possible for the planned measurements. To characterize the detector several measurements will be taken at different measurement geometries. Measurements of the background radiations will be performed before and after the assembly of the lead shielding such that a comparison of the shielding's effect on measurements can be made. These measurements will also be analyzed in an attempt to identify the different radionuclides contributing to the background radiation. The result was a reliable set-up with a good energy resolution. However, more tests are required to gain a greater understanding of the inner structure of the detector.

No description available.

One of the main challenges during the ultra-high count rate gamma-ray spectrometry is the large dead time. Using a LaBr3(Ce) detector (TRT 0.3 µs, TFT 0.5 µs), with an input count rate of 4.8×10E5 cps, the dead time could be as high as 87%. Such high dead time could significantly reduce the quality of the data collected as a considerable number of counts would be lost. Thus, this project aimed to reduce the dead time by modifying the detector system. Based on the setup used by previous research, the new system has its preamp, which is normally used for signal processing, removed. Experiments were made with calibration sources to optimize the new system. The calibration sources (Cs-137 and Co-60), Cs-137 resin sources, and Shephard Cs-137 sources were used to create different count rates, with the highest being 1.22×10E6 cps, for measurements. Side-by-side measurements were performed with the setup with preamp and the one without preamp at various count rates. The analysis, which focused on the dead time and resolution, shows the setup without preamp would have much lower dead time, especially during ultra-high count rate measurements. The method was proved to be successful, for, at 4.8×10E5 cps, the dead time decreased from 87% to 54%. / Thesis / Master of Science (MSc)

With the increasing demand for access to the crowded radio frequency spectrum, cognitive radios have been suggested as one solution. Cognitive radios would be frequency agile and able to sense their radio environment and opportunistically use empty spectrum. Spectrum sensing, monitoring a given band of spectrum to see if it is occupied, is an essential part of a cognitive radio. The preferred method of spectrum sensing is the energy detector, which does not require any a priori information about the signal to be detected and is computationally simple to implement. Man-made noise, impulsive in nature, has also become more prevalent with the widespread use of electronic devices. In this thesis, we took measurements of man-made impulsive noise in the broadcast digital television bands to measure its presence, power, and spatial correlation. The effects of impulsive noise on the detection performance of an energy detector were analyzed. Lastly, a wideband RF receiver was designed, built, and tested on the Virginia Tech campus, which would be well suited both to spectrum sensing and taking measurements of impulsive noise. / Master of Science

The difficulties encountered in quantitative analysis by gas chromatography are discussed, with particular reference to detection systems. The properties of an ideal detector for quantitative analysis are listed. A description is given of the mode of operation of detectors for gas chromatography, and the extent to which they are suitable for quantitative work is assessed. It was concluded that no one detector possessed all the properties required or an ideal detector. In particular a qualitative knowledge of the sample for analysis was required by all detectors; and calibration was required by the majority of detectors. The extent to which the Brunel mass detector overcomes these limitations was assessed. It is shown that the response of the mass detector depends solely on weight changes caused by adsorption of materials eluted from the chromatographic column thus completely eliminating the need for calibration and qualitative information. The response of the detector is integral, so that the problems associated with peak area measurement do not arise. The sensitivity of the detector is of a similar order to conventional hot wire detectors. The detector gave a quantitative response to all materials analysed, covering a wide boiling range: the upper limit was determined by the maximum column operating temperature, and the lower limit by the extent to which the detector was cooled. The detector responded quantitatively to water. At room temperature the detector responded on a qualitative basis to organic and inorganic gases. The detector was used for the calibration of other detector, and was operated in conjunction with the Martin gas density balance to determine the molecular weights of eluted materials.

Táto práca sa zaoberá detekciou semafórov na snímkoch z kamery. Cieľom je nájsť vhodné nastavenie a kombináciu dostupných detektorov. V prvej časti práce je vysvetlený princíp funkcie použitých detektorov. Nasleduje zhodnotenie vlastností jednotlivých detektorov pred ich optimalizáciou. V ďalšej časti práce je popísaný proces testovania a evaluácie detektorov a predstavený nový systém pre zefektívnenie hľadania optimálneho nastavenia detektorov. V rámci optimizácie je popísaný effekt jednotlivých parametrov na chovanie systému a sú navrhnuté rozpätia vhodných hodnôt pre každý parameter. Taktiež je predstavené nové zapojenie detektorov sú nájdené optimálne pracovné body systému. Posledná časť sa zaoberá použitím vhodných metód na filtorvanie a zhlukovanie hypotéz. Nakoniec je prezentovaná celková funkčnosť systému pred a po optimizácii a výsledky sú zhodnotené.

The decay of 33 hour ¹⁴³Ce to levels in ¹⁴³Pr has been studied, using Ge(Li), NaI(Tl), and Si detectors. A number of new gamma ray transitions have been discovered. A decay scheme based on the experimental results is discussed and some spin assignments are suggested. This investigation was not exhaustive and suggestions are made as to further experiments which could be done. / Thesis / Master of Science (MSc)

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The decorrelating detector can afford good data estimates because it does not need to know many parameters of the received signal. However, it shows great performance deprivation when the background noise is high. On the other hand, partial parallel interference canceller(PPIC) has the potential to combat the near-far problem and have much lower computation complexity. But its performance depends on the initial data estimate. An improved PPIC scheme is proposed in this paper to combat the near-far problem. It utilizes the advantages of the two detectors by combining them. The focus of this paper is on the BER performance and the near-far resistance capability of the proposed scheme. Computer simulations demonstrate that the proposed detector has good BER performance and near-far resistance capability.

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No description available.