A Combined Compton and Coded-aperture Telescope for Medium-energy Gamma-ray Astrophysics

A future mission in medium-energy gamma-ray astrophysics would allow for many scientific advancements, e.g. a possible explanation for the excess positron emission from the Galactic Center, a better understanding of nucleosynthesis and explosion mechanisms in Type Ia supernovae, and a look at the physical forces at play in compact objects such as black holes and neutron stars. Additionally, further observation in this energy regime would significantly extend the search parameter space for low-mass dark matter. In order to achieve these objectives, an instrument with good energy resolution, good angular resolution, and high sensitivity is required. In this paper we present the design and simulation of a Compton telescope consisting of cubic-centimeter Cadmium Zinc Telluride (CdZnTe) detectors as absorbers behind a silicon tracker with the addition of a passive coded mask. The goal of the design was to create a very sensitive instrument that is capable of high angular resolution. The simulated telescope showed achievable energy resolutions of 1.68$\%$ FWHM at 511 keV and 1.11$\%$ at 1809 keV, on-axis angular resolutions in Compton mode of 2.63$^{\circ}$ FWHM at 511 keV and 1.30$^{\circ}$ FWHM at 1809 keV, and is capable of resolving sources to at least 0.2$^{\circ}$ at lower energies with the use of the coded mask. An initial assessment of the instrument in Compton imaging mode yields an effective area of 183 cm$^{2}$ at 511 keV and an anticipated all-sky sensitivity of 3.6 x 10$^{-6}$ photons cm$^{-2}$ s$^{-1}$ for a broadened 511 keV source over a 2-year observation time. Additionally, combining a coded mask with a Compton imager to improve point source localization for positron detection has been demonstrated

Molecular evidence of gene integration in Larix decidua somatic embryos after agrobacterium-mediated transformation

Agrobacterium was considered to be the method of choice to introduce foreign genes into plant cells. ESM (embryonal suspensor masses) which is composed of actively dividing immature embryos, could probably be very competent for transformation. An average of 1- 3 clump tissues resistant to hygromycin arose from at least 300 mg ESM of Larix decidua after Agrobacterium inoculation. These clump tissues were able to proliferate further in the selection medium. PCR analysis was carried out using primers corresponding to HPT and GUS-genes. Both primers amplified an internal fragment in size of 650 and 700 base pair lengths respectively. Keywords: conifer â Larix decidua â Agrobacterium -mediated transformation â embryonal suspensor masse

Equity research - Redes Energéticas Nacionais SGPS S.A. : examining DCF valuation model invariance

Mestrado em FinançasEste projeto contém uma análise financeira abrangente das Redes Energéticas Nacionais S.G.P.S, S.A (REN). Foi desenvolvido de acordo com os padrões do projeto final do Mestrado em Finanças do ISEG e escrito de acordo com as diretrizes do CFA Institute Research Challenge. A empresa em causa foi definida pela CFA Society Portugal, que a selecionou de entre as empresas que integram o Índice PSI20. A REN é o único operador e gestor em Portugal da infraestrutura de transmissão terrestres do Sistema Eléctrico Nacional e do Sistema Nacional de Gás Natural. Uma abordagem de soma total das partes (SoP) foi usada para atingir uma recomendação de compra com uma preço alvo de € 2,78 / ação para o final de 2018, implicando um potencial de valorização de +15% sobre a cotação de € 2,43 / ação em 9 de fevereiro. A avaliação principal é complementada com uma análise de robustez sobre a SoP, através da construção de um modelo de valor residual (também conhecido como lucro anormal) para avaliar as ações. O resultado geral confirma as estimativas de preço iniciais, no entanto, é analisado em mais detalhe um pressuposto relevante sobre o rácio price-to-book de longo prazo na avaliação da REN, uma vez que considera-se que este pressuposto causa uma grande variação no preço alvo. As informações utilizadas ao longo deste relatório estavam disponíveis publicamente à data de 9 de fevereiro de 2018, portanto, qualquer informação ou eventos subsequentes não foram considerados.This project contains a comprehensive financial analysis of Redes Energéticas Nacionais S.G.P.S, S.A (REN). It was conducted in accordance with ISEG´s Master in Finance final work project standards and written following the CFA Institute Research Challenge guidelines. The subject company was assigned by CFA Society Portugal who selected it from the Portuguese PSI20 Index. REN is Portugal's sole operator and manager of the National Electric System's mainland transport infrastructure and the National Natural Gas System. A sum-of-the-parts (SoP) FCFF approach was used to reach a BUY recommendation with a 2018YE price target of €2.76/sh, implying a +15% upside potential from the February 9th closing price of €2.43/sh. The original research is extended in the current work to consider the robustness of the SoP valuation by constructing a residual income (also known as abnormal earnings) model to value the shares. The result overall confirms the original price targets, however a strong assumption regarding the long-term price-to-book ratio of REN's valuation is investigated and found to cause large variation in the resulting price targets. The information used throughout this report was publicly available as of February 9, 2018, thus any information or subsequent events have not been considered.info:eu-repo/semantics/publishedVersio

Development of Silicon Strip Detectors for a Medium Energy Gamma-ray Telescope

We report on the design, production, and testing of advanced double-sided silicon strip detectors under development at the Max-Planck-Institute as part of the Medium Energy Gamma-ray Astronomy (MEGA) project. The detectors are designed to form a stack, the "tracker," with the goal of recording the paths of energetic electrons produced by Compton-scatter and pair-production interactions. Each layer of the tracker is composed of a 3 x 3 array of 500 micron thick silicon wafers, each 6 cm x 6 cm and fitted with 128 orthogonal p and n strips on opposite sides (470 micron pitch). The strips are biased using the punch-through principle and AC-coupled via metal strips separated from the strip implant by an insulating oxide/nitride layer. The strips from adjacent wafers in the 3 x 3 array are wire-bonded in series and read out by 128-channel TA1.1 ASICs, creating a total 19 cm x 19 cm position-sensitive area. At 20 degrees C a typical energy resolution of 15-20 keV FWHM, a position resolution of 290 microns, and a time resolution of ~1 microsec is observed.Comment: 9 pages, 13 figures, to appear in NIM-A (Proceedings of the 9th European Symposium on Semiconductor Detectors

The MEGA Advanced Compton Telescope Project

The goal of the Medium Energy Gamma-ray Astronomy (MEGA) telescope is to improve sensitivity at medium gamma-ray energies (0.4-50 MeV) by at least an order of magnitude over that of COMPTEL. This will be achieved with a new compact design that allows for a very wide field of view, permitting a sensitive all-sky survey and the monitoring of transient and variable sources. The key science objectives for MEGA include the investigation of cosmic high-energy particle accelerators, studies of nucleosynthesis sites using gamma-ray lines, and determination of the large-scale structure of galactic and cosmic diffuse background emission. MEGA records and images gamma-ray events by completely tracking both Compton and pair creation interactions in a tracker of double-sided silicon strip detectors and a calorimeter of CsI crystals able to resolve in three dimensions. We present initial laboratory calibration results from a small prototype MEGA telescope.Comment: 7 pages LaTeX, 5 figures, to appear in New Astronomy Reviews (Proceedings of the Ringberg Workshop "Astronomy with Radioactivities III"

NuSTAR Observations of G11.2–0.3

We present in this paper the hard X-ray view of the pulsar wind nebula in G11.2−0.3 and its central pulsar powered pulsar J1811−1925 as seen by NuSTAR. We complement the data with Chandra for a more complete picture and confirm the existence of a hard, power-law component in the shell with photon index Γ = 2.1 ± 0.1, which we attribute to synchrotron emission. Our imaging observations of the shell show a slightly smaller radius at higher energies, consistent with Chandra results, and we find shrinkage as a function of increased energy along the jet direction, indicating that the electron outflow in the PWN may be simpler than that seen in other young PWNe. Combining NuSTAR with INTEGRAL, we find that the pulsar spectrum can be fit by a power law with Γ = 1.32 ± 0.07 up to 300 keV without evidence of curvature