The purpose of this project was to design, construct, and evaluate an alpha spectrometer based on an inexpensive p-i-n photodiode as a radiation detector. The BPX-61 p-i-n photodiode was selected and calculated to have a 93 µm wide sensitive volume at 25 V reverse bias. Electronics consisting of a charge-sensitive preamplifier, a pole-zero canceling CR-(RC)4 pulse shaping amplifier, and an adjustable detector bias voltage supply were devised and assembled. Several alpha spectra were recorded from different alpha radiation sources to determine the performance of the alpha spectrometer. The results show that the alpha spectrometer could successfully and accurately measure alpha spectra, which could then be used to identify radioactive materials present in the sources. An FWHM resolution of about 230 keV was measured for 5.486 MeV alpha particles from Am-241. This resolution is inferior to most alpha spectrometers that measure under vacuum. However, because the device does not require a vacuum pump and uses USB for power and data acquisition, it is a convenient and compact option for field measurements. The low cost and reasonable performance of commercial p-i-n photodiodes as radiation detectors could be appealing for future alpha spectroscopy applications.

Neste trabalho são apresentados os estudos das condições de resposta de um diodo de Si, com estrutura de múltiplos anéis de guarda, na detecção e espectrometria de partículas alfa. Este diodo foi fabricado por meio do processo de implantação iônica (Al/p+/n/n+/Al) em um substrato de Si do tipo n com resistividade de 3 kohm•cm, 300 mícrons de espessura e área útil de 4 mm2. Para usar este diodo como detector, a face n+ deste dispositivo foi polarizada reversamente, o primeiro anel de guarda aterrado e os sinais elétricos extraídos da face p+. Estes sinais eram enviados diretamente a um pré-amplificador desenvolvido em nosso laboratório, baseado no emprego do circuito híbrido A250 da Amptek, seguido da eletrônica nuclear convencional. Os resultados obtidos com este sistema na detecção direta de partículas alfa do Am-241evidenciaram excelente estabilidade de resposta com uma elevada eficiência de detecção (= 100 %). O desempenho deste diodo na espectrometria de partículas alfa foi estudado priorizando-se a influência da tensão de polarização, do ruído eletrônico, da temperatura e da distância fonte-detector na resolução em energia. Os resultados mostraram que a maior contribuição para a deterioração deste parâmetro é devida à espessura da camada morta do diodo (1 mícron). No entanto, mesmo em temperatura ambiente, a resolução medida (FWHM = 18,8 keV) para as partículas alfa de 5485,6 keV (Am-241) é comparável àquelas obtidas com detectores convencionais de barreira de superfície freqüentemente utilizados em espectrometria destas partículas. / In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p+/n/n+/Al) was processed out of 300 micrometers thick, n type substrate with a resistivity of 3 kohm•cm and an active area of 4 mm2. In order to use this diode as a detector, the bias voltage was applied on the n+ side, the first guard ring was grounded and the electrical signals were readout from the p+ side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from Am-241 showed an excellent response stability with a high detection efficiency (= 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 micrometer). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles (Am-241) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry.

Neste trabalho são apresentados os estudos das condições de resposta de um diodo de Si, com estrutura de múltiplos anéis de guarda, na detecção e espectrometria de partículas alfa. Este diodo foi fabricado por meio do processo de implantação iônica (Al/p+/n/n+/Al) em um substrato de Si do tipo n com resistividade de 3 kohm•cm, 300 mícrons de espessura e área útil de 4 mm2. Para usar este diodo como detector, a face n+ deste dispositivo foi polarizada reversamente, o primeiro anel de guarda aterrado e os sinais elétricos extraídos da face p+. Estes sinais eram enviados diretamente a um pré-amplificador desenvolvido em nosso laboratório, baseado no emprego do circuito híbrido A250 da Amptek, seguido da eletrônica nuclear convencional. Os resultados obtidos com este sistema na detecção direta de partículas alfa do Am-241evidenciaram excelente estabilidade de resposta com uma elevada eficiência de detecção (= 100 %). O desempenho deste diodo na espectrometria de partículas alfa foi estudado priorizando-se a influência da tensão de polarização, do ruído eletrônico, da temperatura e da distância fonte-detector na resolução em energia. Os resultados mostraram que a maior contribuição para a deterioração deste parâmetro é devida à espessura da camada morta do diodo (1 mícron). No entanto, mesmo em temperatura ambiente, a resolução medida (FWHM = 18,8 keV) para as partículas alfa de 5485,6 keV (Am-241) é comparável àquelas obtidas com detectores convencionais de barreira de superfície freqüentemente utilizados em espectrometria destas partículas. / In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p+/n/n+/Al) was processed out of 300 micrometers thick, n type substrate with a resistivity of 3 kohm•cm and an active area of 4 mm2. In order to use this diode as a detector, the bias voltage was applied on the n+ side, the first guard ring was grounded and the electrical signals were readout from the p+ side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from Am-241 showed an excellent response stability with a high detection efficiency (= 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 micrometer). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles (Am-241) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry.

The Large Hadron Collider (LHC) at CERN is designed to search for new physics by colliding protons with a center-of-mass energy of 13 TeV. The ATLAS detector is a multipurpose particle detector built to record these proton-proton collisions. In order to improve sensitivity to new physics at the LHC, luminosity increases are planned for 2018 and beyond. With this greater luminosity comes an increase in the number of simultaneous proton-proton collisions per bunch crossing (pile-up). This extra pile-up has adverse effects on algorithms for clustering the ATLAS detector's calorimeter cells. These adverse effects stem from overlapping energy deposits originating from distinct particles and could lead to difficulties in accurately reconstructing events. Machine learning algorithms provide a new tool that has potential to improve clustering performance. Recent developments in computer science have given rise to new set of machine learning algorithms that, in many circumstances, out-perform more conventional algorithms. One of these algorithms, convolutional neural networks, has been shown to have impressive performance when identifying objects in 2d or 3d arrays. This thesis will develop a convolutional neural network model for calorimeter cell clustering and compare it to the standard ATLAS clustering algorithm. / Graduate

The LHC (Large Hadron Collider) will have a long shut down in the years of 2019 and 2020, referred to as LS2. During this stop the LHC injector complex will be upgraded to increase the luminosities, which will be the first step of the high luminosity LHC program (which will be realized during LS3 that takes place in 2024-2026). The LHCb experiment, whose main purpose is to study the CP-violation, will during this long stop be upgraded in order to withstand a higher radiation dose, and to be able to read out the detector at a rate of 40MHz,compared to 1MHz at present. This change will improve the trigger efficiency significantly. One of the LHCb sub-detectors the Trigger Tracker (TT), will be replaced by a new sub-detector called UT. This report presents the early stage design (preparation for mock-up building) of the box that will be isolating the new UT detector from the surroundings and to ensure optimal detector operation. Methods to fulfill requirements such as light and gas tightness, Faraday-cage behavior and condensation free temperatures, without breaking the fragile beryllium beam pipe, are established. / LHC (Large Hadron Collider) kommer under åren 2019-2020 att ha ett längre driftstopp. Under detta driftstopp så kommer LHC's injektionsanordningar att uppgraderas för att kunna sätta fler protoner i circulation i LHC, och därmed öka antalet partikelkollisioner per tidsenhet. Denna uppgradering kommer att vara första steget i "High Luminocity LHC"-programmet som kommer att realiseras år 2024-2026. LHCb-experimentet, vars främsta syfte är att studera CP-brott, kommer också att uppgraderas under stoppet 2019-2020. Framför allt så ska avläsningsfrekvensen ökas från dagens 1MHz till 40MHz, och experimentet ska förberedas för de högre strålningsdoser som kommer att bli aktuella efter stoppet 2024-2026. En av LHCb's deldetektorer, TT detektorn, kommer att bytas ut mot en ny deldetektor som kallas UT. Den här rapporten presenterar den förberedande designen av den låda som ska isolera UT från dess omgivning och försäkra optimala förhållanden för detektorn. Kraven på den isolerande lådan och tillvägagångssätt för att uppfylla dessa krav presenteras. / LHCb, LS2 and LS3 Upgrade

In July 2031, a new chapter in the exploration of the Jovian system will begin with the arrival of the Jupiter Icy Moons Explorer (Juice) at Jupiter. Launched on April 14 2024 as part of ESA’s Cosmic Vision programme, the mission aims to study Jupiter and its icy Galilean moons Callisto, Europa, and Ganymede. Juice carries a whole suite of instruments for in-situ and remote ground observations, one of which is the Jovian plasma Dynamics and Composition analyser (JDC). As a part of the Particle Environment Package (PEP), the particle detector will measure the energy, mass, charge and arrival direction of ions and electrons in the Jovian magnetosphere. Spacecraft charging caused by interactions between the spacecraft and its surrounding plasma environment poses a significant problem for JDC because the electrostatic potential of the spacecraft accelerates/decelerates charged particles, resulting in distorted measurements, particularly for the lowest energy particles.  In this report, we show the results of spacecraft charging and instrument simulations performed in the Spacecraft Plasma Interaction System (SPIS) for the solar wind and Earth’s magnetosheath—two environments that Juice will encounter at the start of the cruise phase. We found that the conductive surfaces that cover the majority of the spacecraft become positively charged as a result of a large photoelectron current in both the solar wind and magnetosheath environments. We show that these surfaces are expected to reach potentials of 9 V in the solar wind and 4 V in the magnetosheath. The four radiators on Juice that are covered with dielectric paint and shaded by the sun shield become negatively charged in both simulated environments. The radiator potentials can be as low as -40 V in the solar wind and -100 V in the magnetosheath. We also conclude that due to blocking by the spacecraft main body, the ion population cannot be sampled in the solar wind unless a spacecraft roll is performed. Furthermore, due to the high ion f low energy, spacecraft charging will not influence JDC measurements in this environment.  In the magnetosheath, the ion population can be sampled by JDC, and we identified three distortion mechanisms: (1) repulsion by the main body, (2) attraction by two of the radiators, and (3) repulsion by the MAG boom. Of all the distortion modes, the one originating from a negatively charged (-67.8 V) radiator close to JDC is the strongest, affecting ions with energies above 80 eV. The least powerful but most prevalent mode is the repulsion of ions by the main body. Our results can be compared with future in-situ measurements to identify distortion mechanisms well ahead of the science phase in which the scientifically important measurements will be carried out.