Development of a Digital Feedback System for Advanced Ion Manipulation Techniques within a Penning Trap

The high-precision Penning-trap mass spectrometer Pentatrap aims at measurements of mass ratios of highly charged ions with an uncertainty of a few parts in 10−12. Within the context of this thesis, the development of an active feedback system and its possible applications for the Pentatrap experiment are described. This system allows to electronically feed back the signal from the axial detection electronics to one or multiple electrodes of the Penning trap, enabling the implementation of advanced ion manipulation techniques. It was successfully used to cool the apparent temperature of the detection electronics below the 4.2 K environment of the trap setup, enabling the application of ion feedback cooling. Furthermore, the quality-factor and the center frequency of the resonator, used in the detection system, was shown to be modified by coupling the feedback signal to the resonator. The feedback system was implemented using a novel concept, making use of real-time digital processing algorithms on an FPGA. This leads to very stable feedback operation and allows for highly dynamic variation of the feedback parameters, opening the possibility for new measurement schemes. A phase-sensitive measurements technique for the axial frequency was successfully implemented and tested, which inherently has the potential to achieve better accuracy compared to the commonly used axial dip detection. Additionally, a single-ion self-excited oscillator was realized, enabling the determination of the axial frequency at very high repetition rates. As the precision of the Pentatrap experiment is currently mainly limited by the uncertainty of the axial frequency measurement, the feedback system developed in this thesis will directly contribute to improving the precision of the mass measurements

Geologic Map of the Olympia Cavi Region of Mars (MTM 85200): A Summary of Tactical Approaches

The 1:500K-scale geologic map of MTM 85200 - the Olympia Cavi region of Mars - has been submitted for peer review [1]. Physiographically, the quadrangle includes portions of Olympia Rupes, a set of sinuous scarps which elevate Planum Boreum ~800 meters above Olympia Planum. The region includes the high-standing, spiral troughs of Boreales Scopuli, the rugged and deep depressions of Olympia Cavi, and the vast dune fields of Olympia Undae. Geologically, the mapped units and landforms reflect the recent history of repeated accumulation and degradation. The widespread occurrence of both weakly and strongly stratified units implicates the drape-like accumulation of ice, dust, and sand through climatic variations. Similarly, the occurrence of layer truncations, particularly at unit boundaries, implicates punctuated periods of both localized and regional erosion and surface deflation whereby underlying units were exhumed and their material transported and re-deposited. Herein, we focus on the iterative mapping approaches that allowed not only the accommodation of the burgeoning variety and volume of data sets, but also facilitated the efficient presentation of map information. Unit characteristics and their geologic history are detailed in past abstracts [2-3]

Groundbased monitoring of Martian atmospheric opacity

The amount of dust in the Martian atmosphere is variable in both space and time. The presence of aerosols in the Mars atmosphere complicates quantitative analysis of Martian surface properties. We have developed a model for Mars surface and atmospheric scattering based on equations in Hillier et al (1991). This formulation was chosen for its speed of computation and because it accounts for the spherical geometry of atmospheric scattering at high mission angles, i.e., near the planetary limb

A escrita literária e a Olimpíada de Língua Porutguesa Escrevendo o futuro: memórias de uma professora

Esta tese articula Literatura e Educação ao referencial teórico da História Cultural, de Roger Chartier (representações, apropriações e práticas), com objetivo de analisar o ensino de escrita literária nos anos finais do ensino fundamental, com contribuições teóricas de Tauveron (2014) e Dalla-Bona (2012), Geraldi (2011), Calkins (1989), Vigotski (2009). Objetiva, especificamente, analisar a proposta pedagógica do Caderno do Professor, do programa oficial Olimpíada de Língua Portuguesa Escrevendo o Futuro, que orienta o trabalho com a escrita do gênero textual Memórias literárias . Tem como sujeitos de pesquisa 26 professores de Língua Portuguesa da Rede Municipal de Ensino da Serra/ES, participantes da formação continuada, identificando perfis a partir de suas histórias de leitura e escrita literárias, formação inicial e concepções sobre literatura e seu ensino, por meio de questionário e entrevista semiestruturada. Por fim, descreve e analisa o portfólio de uma professora, que registra seu planejamento e trabalho com o gênero Memórias literárias. Conclui que: a) O gênero, como o título anuncia, aborda conteúdos e práticas da esfera literária. O discurso da Olimpíada, entretanto, num jogo ambíguo de incentivo e contenção, não evidencia a relação das escritas dos alunos com a escrita de escritores experientes, ambas compreendidas nesta tese como escritas de intenção artística (TAUVERON, 2014), o que analiso como instrumentalização da literatura, pretexto para ensino de habilidades escritoras em geral; b) A seleção de textos literários privilegia memórias de descendentes europeus, contribuindo para a construção de uma representação memorialista que exclui a memória ancestral da maioria dos estudantes das escolas públicas da Serra/ES, a memória de matriz africana; c) a apropriação da proposta pedagógica do caderno pela professora abrevia a etapa de revisão, o que leva a inferir uma concepção de escrita como produto e não como processo, porém, investe na motivação para a escrita literária e na publicação dos textos dos alunos, estratégias importantes para desenvolvimento de um comportamento de autor (TAUVERON, 2014), valorizando o trabalho com o gênero Memórias literárias como forma de conhecimento da história e da cultura do município para a criação de vínculos de pertencimento

Crater population and resurfacing of the Martian north polar layered deposits

Present-day accumulation in the north polar layered deposits (NPLD) is thought to occur via deposition on the north polar residual cap. Understanding current mass balance in relation to current climate would provide insight into the climatic record of the NPLD. To constrain processes and rates of NPLD resurfacing, a search for craters was conducted using images from the Mars Reconnaissance Orbiter Context Camera. One hundred thirty craters have been identified on the NPLD, 95 of which are located within a region defined to represent recent accumulation. High Resolution Imaging Science Experiment images of craters in this region reveal a morphological sequence of crater degradation that provides a qualitative understanding of processes involved in crater removal. A classification system for these craters was developed based on the amount of apparent degradation and infilling and where possible depth/diameter ratios were determined. The temporal and spatial distribution of crater degradation is interpreted to be close to uniform. Through comparison of the size-frequency distribution of these craters with the expected production function, the craters are interpreted to be an equilibrium population with a crater of diameter D meters having a lifetime of ~30.75D^(1.14) years. Accumulation rates within these craters are estimated at 7.2D^(−0.14) mm/yr, which corresponds to values of ~3–4 mm/yr and are much higher than rates thought to apply to the surrounding flat terrain. The current crater population is estimated to have accumulated in the last ~20 kyr or less

Opportunity Microscopic Imager Results from the Western Rim of Endeavour Crater

The Athena science payload on the Mars Exploration Rovers (MER Spirit and Opportunity) includes the Microscopic Imager (MI), a fixed focus close-up camera mounted on the instrument arm. The MI acquires images at a scale of 31 micrometers/pixel over a broad spectral range (400 to 700 nm) using only natural illumination of target surfaces. Radio signals from Spirit have not been received since March 2010, so attempts to communicate with that rover ceased in mid-2011. The Opportunity MI optics were contaminated by a global dust storm in 2007. That contamination continues to reduce the contrast of MI images, and is being monitored by occasionally imaging the sky

A digital feedback system for advanced ion manipulation techniques in Penning traps

The possibility to apply active feedback to a single ion in a Penning trap using a fully digital system is demonstrated. Previously realized feedback systems rely on analog circuits that are susceptible to environmental fluctuations and long term drifts, as well as being limited to the specific task they were designed for. The presented system is implemented using an FPGA-based platform (STEMlab), offering greater flexibility, higher temporal stability and the possibility for highly dynamic variation of feedback parameters. The system's capabilities were demonstrated by applying feedback to the ion detection system primarily consisting of a resonant circuit. This allowed shifts in its resonance frequency of up to several kHz and free modification of its quality factor within two orders of magnitude, which reduces the temperature of a single ion by a factor of 6. Furthermore, a phase-sensitive detection technique for the axial ion oscillation was implemented, which reduces the current measurement time by two orders of magnitude while simultaneously eliminating model-related systematic uncertainties. The use of FPGA technology allowed the implementation of a fully-featured data acquisition system, making it possible to realize feedback techniques that require constant monitoring of the ion signal. This was successfully used to implement a single-ion self-excited oscillator.Comment: The following article has been accepted by Review of Scientific Instruments. After it is published, it will be found at https://aip.scitation.org/journal/rs

Mineralogy and chemistry of cobbles at Meridiani Planum, Mars, investigated by the Mars Exploration Rover Opportunity

Numerous loose rocks with dimensions of a few centimeters to tens of centimeters and with no obvious physical relationship to outcrop rocks have been observed along the traverse of the Mars Exploration Rover Opportunity. To date, about a dozen of these rocks have been analyzed with Opportunity’s contact instruments, providing information about elemental chemistry (Alpha Particle X‐ray Spectrometer), iron mineralogy and oxidation states (Mössbauer Spectrometer) and texture (Microscopic Imager). These “cobbles” appear to be impact related, and three distinct groups can be identified on the basis of chemistry and mineralogy. The first group comprises bright fragments of the sulfate‐rich bedrock that are compositionally and texturally indistinguishable from outcrop rocks. All other cobbles are dark and are divided into two groups, referred to as the “Barberton group” and the “Arkansas group,” after the first specimen of each that was encountered by Opportunity. Barberton group cobbles are interpreted as meteorites with an overall chemistry and mineralogy consistent with a mesosiderite silicate clast composition. Arkansas group cobbles appear to be related to Meridiani outcrop and contain an additional basaltic component. They have brecciated textures, pointing to an impact‐related origin during which local bedrock and basaltic material were mixed

Sulfate Deposition in Regolith Exposed in Trenches on the Plains Between the Spirit Landing Site and Columbia Hills in Gusev Crater, Mars

During its exploration within Gusev crater between sol 01 and sol 158, the Spirit rover dug three trenches (Fig. 1) to expose the subsurface regolith [1, 2, 9]. Laguna trench (approx. 6 cm deep, approx.203 m from the rim of Bonneville crater) was dug in Laguna Hollow at the boundary of the impact ejecta from Bonneville crater and the surrounding plains. The Big Hole trench (approx. 6-7 cm deep) and The Boroughs trench (approx. 11 cm deep) were dug in the plains between the Bonneville crater and the Columbia Hills (approx.556 m and approx.1698 m from the rim of Bonneville crater respectively). The top, wall and floor regolith of the three trenches were investigated using the entire set of Athena scientific instruments [10]

Detailed stratigraphy and bed thickness of the Mars north and south polar layered deposits

The Mars polar layered deposits (PLD) likely hold an extensive record of recent climate during a period of high-amplitude orbit and obliquity cycles. Previous work has detected limited evidence for orbital signatures within PLD stratigraphy, but data from the High Resolution Imaging Science Experiment (HiRISE) permit renewed analysis of PLD stratigraphy at sub-meter scale. Topography derived from HiRISE images using stereogrammetry resolves beds previously detectable only as alternating light and dark bands in visible images. We utilize these data to measure the thickness of individual beds within the PLD, corrected for non-horizontal bed orientation. Stratigraphic columns and bed thickness profiles are presented for two sites within the NPLD, and show several sets of finely bedded units 1–2 m thick; isolated marker beds 3–4 m thick; and undifferentiated sections. Bed thickness measurements for three sites within the SPLD exhibit only one bed type based on albedo and morphology, and bed thicknesses have a larger mean and variance compared to measurements for the NPLD. Power spectra of brightness and slope derived along the measured stratigraphic sections confirm the regularity of NPLD fine bed thickness, and the lack of a dominant SPLD bed thickness. The regularity of fine bed thickness of the NPLD is consistent with quasiperiodic bed formation, albeit with unknown temporal period; the SPLD thickness measurements show no such regularity