88 research outputs found
Indicadores de sustentabilidade na visão de agricultores familiares como instrumento para gestão de unidades de produção com pecuária de leite.
O objetivo deste trabalho foi construir de forma participativa um instrumento de gestão de unidades de produção de base familiar com pecuária de leite, constituído por indicadores de sustentabilidade. O trabalho foi conduzido no âmbito do Programa Rede Leite, na região noroeste do Rio Grande do Sul, tendo como base teórico-metodológica a Pesquisa-Desenvolvimento.Organizadores Lírio José Reichert, Pedro Selvino Neumann, Lovois de Andrade Miguel
Exploring CEvNS with NUCLEUS at the Chooz Nuclear Power Plant
Coherent elastic neutrino-nucleus scattering (CENS) offers a unique way
to study neutrino properties and to search for new physics beyond the Standard
Model. Nuclear reactors are promising sources to explore this process at low
energies since they deliver large fluxes of (anti-)neutrinos with typical
energies of a few MeV. In this paper, a new-generation experiment to study
CENS is described. The NUCLEUS experiment will use cryogenic detectors
which feature an unprecedentedly low energy threshold and a time response fast
enough to be operated in above-ground conditions. Both sensitivity to
low-energy nuclear recoils and a high event rate tolerance are stringent
requirements to measure CENS of reactor antineutrinos. A new experimental
site, denoted the Very-Near-Site (VNS) at the Chooz nuclear power plant in
France is described. The VNS is located between the two 4.25 GW
reactor cores and matches the requirements of NUCLEUS. First results of on-site
measurements of neutron and muon backgrounds, the expected dominant background
contributions, are given. In this paper a preliminary experimental setup with
dedicated active and passive background reduction techniques is presented.
Furthermore, the feasibility to operate the NUCLEUS detectors in coincidence
with an active muon-veto at shallow overburden is studied. The paper concludes
with a sensitivity study pointing out the promising physics potential of
NUCLEUS at the Chooz nuclear power plant
First results from the CRESST-III low-mass dark matter program
The CRESST experiment is a direct dark matter search which aims to measure
interactions of potential dark matter particles in an earth-bound detector.
With the current stage, CRESST-III, we focus on a low energy threshold for
increased sensitivity towards light dark matter particles. In this manuscript
we describe the analysis of one detector operated in the first run of
CRESST-III (05/2016-02/2018) achieving a nuclear recoil threshold of 30.1eV.
This result was obtained with a 23.6g CaWO crystal operated as a cryogenic
scintillating calorimeter in the CRESST setup at the Laboratori Nazionali del
Gran Sasso (LNGS). Both the primary phonon/heat signal and the simultaneously
emitted scintillation light, which is absorbed in a separate
silicon-on-sapphire light absorber, are measured with highly sensitive
transition edge sensors operated at ~15mK. The unique combination of these
sensors with the light element oxygen present in our target yields sensitivity
to dark matter particle masses as low as 160MeV/c.Comment: 9 pages, 9 figure
Análise de endemismo de táxons neotropicais de Pentatomidae (Hemiptera: Heteroptera)
The definition of areas of endemism is central to studies of historical biogeography, and their interrelationships are fundamental questions. Consistent hypotheses for the evolution of Pentatomidae in the Neotropical region depend on the accuracy of the units employed in the analyses, which in the case of studies of historical biogeography, may be areas of endemism. In this study, the distribution patterns of 222 species, belonging to 14 Pentatomidae (Hemiptera) genera, predominantly neotropical, were studied with the Analysis of Endemicity (NDM) to identify possible areas of endemism and to correlate them to previously delimited areas. The search by areas of endemism was carried out using grid-cell units of 2.5° and 5° latitude-longitude. The analysis based on groupings of grid-cells of 2.5° of latitude-longitude allowed the identification of 51 areas of endemism, the consensus of these areas resulted in four clusters of grid-cells. The second analysis, with grid-cells units of 5° latitude-longitude, resulted in 109 areas of endemism. The flexible consensus employed resulted in 17 areas of endemism. The analyses were sensitive to the identification of areas of endemism in different scales in the Atlantic Forest. The Amazonian region was identified as a single area in the area of consensus, and its southeastern portion shares elements with the Chacoan and Paraná subregions. The distribution data of the taxa studied, with different units of analysis, did not allow the identification of individual areas of endemism for the Cerrado and Caatinga. The areas of endemism identified here should be seen as primary biogeographic hypotheses.A definição de áreas de endemismo é central aos estudos de Biogeografia Histórica e suas inter-relações são questões fundamentais. Hipóteses consistentes sobre a evolução de Pentatomidae (Hemiptera) na Região Neotropical dependem da acuidade das unidades empregadas nas análises, que no caso de estudos de biogeografia histórica, podem ser áreas endêmicas. Neste trabalho foram estudados os padrões de distribuição de 222 espécies, pertencentes a 14 gêneros de Pentatomidae, com ocorrência predominantemente neotropical, com base em uma Análise de Endemicidade (NDM) a fim de inferir possíveis áreas endêmicas e relacioná-las a áreas previamente delimitadas. A busca por áreas endêmicas foi realizada com quadrículas de 2,5° e 5° latitude-longitude. A análise com base em agrupamentos de 2,5° latitude-longitude permitiu identificar 51 áreas de endemismo, sendo que o consenso destas áreas resultou em quatro agrupamentos de quadrículas. A segunda análise, com quadrículas de 5° latitude-longitude, resultou em 109 áreas de endemismo. O consenso flexível empregado resultou em 17 áreas de endemismo. As análises foram sensíveis à identificação de áreas de endemismo na Mata Atlântica em diferentes escalas. A região Amazônica foi identificada como uma área única no consenso, sendo que a porção sudeste compartilha elementos com as sub-regiões do Chaco e Paraná. Os dados de distribuição dos táxons estudados, com diferentes unidades de análises, não permitiram a identificação de áreas endêmicas para o Cerrado e a Caatinga. As áreas de endemismo aqui identificadas devem ser tratadas como hipóteses biogeográficas primárias.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal do Rio Grande do Sul Laboratório de Entomologia Sistemática Departamento de ZoologiaUniversidade Federal do Paraná Departamento de Zoologia Programa de Pós-Graduação em EntomologiaUniversidade Federal de São Paulo (UNIFESP) Departamento de Ciências BiológicasUNIFESP, Depto. de Ciências BiológicasSciEL
Towards an automated data cleaning with deep learning in CRESST
The CRESST experiment employs cryogenic calorimeters for the sensitive
measurement of nuclear recoils induced by dark matter particles. The recorded
signals need to undergo a careful cleaning process to avoid wrongly
reconstructed recoil energies caused by pile-up and read-out artefacts. We
frame this process as a time series classification task and propose to automate
it with neural networks. With a data set of over one million labeled records
from 68 detectors, recorded between 2013 and 2019 by CRESST, we test the
capability of four commonly used neural network architectures to learn the data
cleaning task. Our best performing model achieves a balanced accuracy of 0.932
on our test set. We show on an exemplary detector that about half of the
wrongly predicted events are in fact wrongly labeled events, and a large share
of the remaining ones have a context-dependent ground truth. We furthermore
evaluate the recall and selectivity of our classifiers with simulated data. The
results confirm that the trained classifiers are well suited for the data
cleaning task.Comment: 12 pages, 8 figures, 6 table
Simulation-based design study for the passive shielding of the COSINUS dark matter experiment
The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation
Underground Searches) experiment aims at the detection of dark matter-induced
recoils in sodium iodide (NaI) crystals operated as scintillating cryogenic
calorimeters. The detection of both scintillation light and phonons allows
performing an event-by-event signal to background discrimination, thus
enhancing the sensitivity of the experiment. The construction of the
experimental facility is foreseen to start by 2021 at the INFN Gran Sasso
National Laboratory (LNGS) in Italy. It consists of a cryostat housing the
target crystals shielded from the external radioactivity by a water tank
acting, at the same time, as an active veto against cosmic ray-induced events.
Taking into account both environmental radioactivity and intrinsic
contamination of materials used for cryostat, shielding and infrastructure, we
performed a careful background budget estimation. The goal is to evaluate the
number of events that could mimic or interfere with signal detection while
optimising the geometry of the experimental setup. In this paper we present the
results of the detailed Monte Carlo simulations we performed, together with the
final design of the setup that minimises the residual amount of background
particles reaching the detector volume.Comment: 12 pages, 7 figure
Cryogenic characterization of a LiAlO 2 crystal and new results on spin-dependent dark matter interactions with ordinary matter: CRESST Collaboration
In this work, a first cryogenic characterization of a scintillating LiAlO 2 single crystal is presented. The results achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut für Kristallzüchtung (IKZ) have been tested to study different properties at cryogenic temperatures. Firstly, two 2.8 g twin crystals were used to build different detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of LiAlO 2 at cryogenic temperatures. The second achieved an energy threshold of (213.02 ± 1.48) eV which allows setting a competitive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses between 350MeV/c2 and 1.50GeV/c2. Secondly, a detector module with a 373 g LiAlO 2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazionali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux monitor for low-background experiments. © 2020, The Author(s)
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Lithium-Containing Crystals for Light Dark Matter Search Experiments
In the current direct dark matter search landscape, the leading experiments in the sub-GeV mass region mostly rely on cryogenic techniques which employ crystalline targets. One attractive type of crystals for these experiments is those containing lithium, due to the fact that 7Li is an ideal candidate to study spin-dependent dark matter interactions in the low mass region. Furthermore, 6Li can absorb neutrons, a challenging background for dark matter experiments, through a distinctive signature which allows the monitoring of the neutron flux directly on site. In this work, we show the results obtained with three different detectors based on LiAlO2, a target crystal never used before in cryogenic experiments
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