524 research outputs found
Performance of a Low Noise Front-end ASIC for Si/CdTe Detectors in Compton Gamma-ray Telescope
Compton telescopes based on semiconductor technologies are being developed to
explore the gamma-ray universe in an energy band 0.1--20 MeV, which is not well
covered by the present or near-future gamma-ray telescopes. The key feature of
such Compton telescopes is the high energy resolution that is crucial for high
angular resolution and high background rejection capability. The energy
resolution around 1 keV is required to approach physical limit of the angular
resolution due to Doppler broadening. We have developed a low noise front-end
ASIC (Application-Specific Integrated Circuit), VA32TA, to realize this goal
for the readout of Double-sided Silicon Strip Detector (DSSD) and Cadmium
Telluride (CdTe) pixel detector which are essential elements of the
semiconductor Compton telescope. We report on the design and test results of
the VA32TA. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV
and 122 keV at 0 degree C with a DSSD and 1.7 keV (FWHM) with a CdTe detector.Comment: 6 pages, 7 figures, IEEE style file, to appear in IEEE Trans. Nucl.
Sc
Plant sources of Amazon rosewood oil.
The aim of this study is to reevaluate the plant sources of the Amazon rosewood oil which have been named Aniba rosaeodora Ducke and Aniba duckei Kosterm. There is some disagreement on the exact botanical status of these species. Some Lauraceae specialists analyzing available material from both species concluded that there is no basis for regarding them as different. Based on our results we are confirming that the chemical composition of both species is quite different from that previously reported. So we are suggesting to bring back the previous botanical rosewood status as proposed by Adolph Ducke
Aplicação de sistemas de avaliação da aptidão agrícola das terras em solos do Estado do Acre, Amazônia.
Os métodos de avaliação da aptidão agrícola tem como objetivo orientar o uso adequado das terras, porém seus resultados apresentam elevado grau de subjetividade devido a serem dependentes da experiência do usuário. Neste trabalho objetivou-se avaliar o uso de um algoritmo para interpretação de propriedades do solo e características da paisagem e compará-lo com a interpretação obtida por um grupo controle, constituído por seis especialistas. Foram utilizadas amostras de solo coletadas por tradagem ao lado dos perfis pedológicos da IX Reunião Brasileira de Correlação e Classificação de Solos, de modo a obter os dados de entrada do algoritmo, enquanto os avaliadores utilizaram os dados físicos, químicos e morfológicos dos perfis pedológicos. A avaliação do grupo controle não identificou as potencialidades para o uso dos solos na Amazônia de forma consistente, enquanto, o algoritmo mostrou-se promissor na avaliação da aptidão para Latossolo, Argissolos, Vertissolos e Luvissolo, no entanto, ainda requer revisões em algumas regras de interpretação para uma avaliação mais coerente da aptidão, principalmente, para o Espodossolo
Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Data Handling Overview
The GLAST Balloon Flight Engineering Model (BFEM) represents one of 16 towers
that constitute the Large Area Telescope (LAT), a high-energy (>20 MeV)
gamma-ray pair-production telescope being built by an international partnership
of astrophysicists and particle physicists for a satellite launch in 2006. The
prototype tower consists of a Pb/Si pair-conversion tracker (TKR), a CsI
hodoscopic calorimeter (CAL), an anti-coincidence detector (ACD) and an
autonomous data acquisition system (DAQ). The self-triggering capabilities and
performance of the detector elements have been previously characterized using
positron, photon and hadron beams. External target scintillators were placed
above the instrument to act as sources of hadronic showers. This paper provides
a comprehensive description of the BFEM data-reduction process, from receipt of
the flight data from telemetry through event reconstruction and background
rejection cuts. The goals of the ground analysis presented here are to verify
the functioning of the instrument and to validate the reconstruction software
and the background-rejection scheme.Comment: 5 pages, 4 figures, to be published in IEEE Transacations on Nuclear
Science, August 200
Avaliação das características de palha de diferentes cultivares de milho na região de Goianésia, GO.
Performance of Long Modules of Silicon Microstrip Detectors
This note describes the performance of modules assembled with up to twelve silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal--to--noise ratio of 19, a hit finding efficiency of 99.8\% and a spatial resolution of 6.0 m. Laboratory measurements indicate that modules of twelve detectors exhibit a signal--to--noise ratio of the order of 16
Constraints on dark matter models from a Fermi LAT search for high-energy cosmic-ray electrons from the Sun
During its first year of data taking, the Large Area Telescope (LAT) onboard
the Fermi Gamma-Ray Space Telescope has collected a large sample of high-energy
cosmic-ray electrons and positrons (CREs). We present the results of a
directional analysis of the CRE events, in which we searched for a flux excess
correlated with the direction of the Sun. Two different and complementary
analysis approaches were implemented, and neither yielded evidence of a
significant CRE flux excess from the Sun. We derive upper limits on the CRE
flux from the Sun's direction, and use these bounds to constrain two classes of
dark matter models which predict a solar CRE flux: (1) models in which dark
matter annihilates to CREs via a light intermediate state, and (2) inelastic
dark matter models in which dark matter annihilates to CREs.Comment: 18 pages, 8 figures, accepted for publication in Physical Review D -
contact authors: Francesco Loparco ([email protected]), M. Nicola Mazziotta
([email protected]) and Jennifer Siegal-Gaskins ([email protected]
Autochthonous bacterium Lactobacillus plantarum as probiotic supplementation for productive performance and sanitary improvements on clownfish Amphiprion ocellaris.
This current study evaluated the probiotic dietary supplementation with autochthonous bacterium Lactobacillus plantarum for Amphiprion ocellaris. Therefore, it was performed an experiment in complete randomized design with four treatments (T1: Control without probiotic; T2: 104 ; T3: 106 and T4: 108 CFU/g of ration) and three replicates. Juvenile fish (n = 120; 0.46 ± 0.01 g and 0.26 ± 0.06 cm) were distributed in twelve aquarium(80 L) and it received trial meal three times a day at fed rate of 4% live weight during 90 days. The fish were monthly measured and determined the total length, standard length, height, weight gain, biomass gain, specific growth rate, apparently feed conversion, relative condition factor, uniformity and survival. At the end of experiment (90 days) fish were submitted to hematological (n = 9/ treatment; Erythrogram, Leukogram and Thrombogram) and histological analysis (n = 6/ treatment; Intestinal tract). Also, after the supplementation period, the fish were challenged with pathogenic bacteria and the survival and blood analyzed. Results showed the fish fed T3 and T4 had improvement on weight gain, feed conversion, specific growth rate, height and total height from the intestinal villi. Increases of red blood cell (Erythrocyte, hematocrit and hemoglobin) and white blood cell (Lymphocyte and monocyte) also observed to both treatments (T3 and T4), However the T4 promoted the greater fish resistance to pathogenic bacteria. As conclusion, probiotic supplementation with the autochthonous bacterium Lactobacillus plantarum 106 CFU/g provides zootechnical improvement for clownfish rearing, but to improve the pathogenic infection resistance, the 108 CFU/g presented more adequate
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