The DarkSide project

DarkSide is a graded experimental project based on radiopure argon, and is now, and will be, used in direct dark matter searches. The present DarkSide-50 detector, operating at the Gran Sasso National Laboratory, is a dual-phase, 50 kg, liquid argon time-projection-chamber surrounded by an active liquid scintillator veto. It is designed to be background free in 3 years of operation. DS-50 performances, when filled with atmospheric argon, are reporte

Neutrino Telescopes as a Direct Probe of Supersymmetry Breaking

We consider supersymmetric models where the scale of supersymmetry breaking lies between 5 $\times 10^6$ GeV and 5 $\times 10^8$ GeV. In this class of theories, which includes models of gauge mediated supersymmetry breaking, the lightest supersymmetric particle is the gravitino. The next to lightest supersymmetric particle is typically a long lived charged slepton with a lifetime between a microsecond and a second, depending on its mass. Collisions of high energy neutrinos with nucleons in the earth can result in the production of a pair of these sleptons. Their very high boost means they typically decay outside the earth. We investigate the production of these particles by the diffuse flux of high energy neutrinos, and the potential for their observation in large ice or water Cerenkov detectors. The relatively small cross-section for the production of supersymmetric particles is partially compensated for by the very long range of heavy particles. The signal in the detector consists of two parallel charged tracks emerging from the earth about 100 meters apart, with very little background. A detailed calculation using the Waxman-Bahcall limit on the neutrino flux and realistic spectra shows that km$^3$ experiments could see as many as 4 events a year. We conclude that neutrino telescopes will complement collider searches in the determination of the supersymmetry breaking scale, and may even give the first evidence for supersymmetry at the weak scale.Comment: 4 pages, 3 figure

The veto system of the DarkSide-50 experiment

Nuclear recoil events produced by neutron scatters form one of the most important classes of background in WIMP direct detection experiments, as they may produce nuclear recoils that look exactly like WIMP interactions. In DarkSide-50, we both actively suppress and measure the rate of neutron-induced background events using our neutron veto, composed of a boron-loaded liquid scintillator detector within a water Cherenkov detecto

Deep shower interpretation of the cosmic ray events observed in excess of the Greisen-Zatsepin-Kuzmin energy

We consider the possibility that the ultra-high-energy cosmic ray flux has a small component of exotic particles which create showers much deeper in the atmosphere than ordinary hadronic primaries. It is shown that applying the conventional AGASA/HiRes/Auger data analysis procedures to such exotic events results in large systematic biases in the energy spectrum measurement. SubGZK exotic showers may be mis-reconstructed with much higher energies and mimick superGZK events. Alternatively, superGZK exotic showers may elude detection by conventional fluorescence analysis techniques.Comment: 22 pages, 5 figure

Local representations of change and conservation of the riparian forests along the São Francisco River (Northeast Brazil).

Investigations of local representations about the environment allow for the elucidation of historical landscape transformation and the elaboration of strategies for environmental conservation. Thus, this study aimed to answer the following questions. How does the local population represent the possible changes in riparian vegetation over time? What historical events were responsible for these possible changes? How does the local population represent concerns related to the use andmaintenance of riparian vegetation? This study was carried out with 87 informants from three communities: two rural ex-settlement communities and one quilombo in Northeastern Brazil. According to the informants, therewere changes in the riparian vegetation. Themain causes of these changes include the type of agriculture practiced in the region and the building of a large dam to provide water to the city of Sobradinho in the state of Bahia. However, there was no significant difference between the number of informants who said that the changes were for the worse and those who said that they were for the better. In addition, the respondents reported an increase in the abundance of exotic species and a decrease in the abundance of native species. Thus, the importance of including this group of people in the process of the forest restoration that will occur in the region is emphasized because they possess information about the past vegetation changes and their causes. They can also indicatewhich species should be prioritized for replanting according to their usage needs and they understand the importance of conserving riparian vegetation

Representações dos proprietários e funcionários de fazendas sobre as mudanças e conservação da vegetação ciliar às margens do rio São Francisco, Nordeste do Brasil.

No Brasil, foi marcante a ocupação de grupos humanos em áreas com potencial hídrico elevado para o desenvolvimento da agricultura irrigada. Neste contexto, inseri-se o rio São Francisco, que vem passando por constantes mudanças em relação à sua cobertura vegetal original. O presente estudo buscou responder as seguintes perguntas: Como fazendeiros e funcionários representam as possíveis mudanças da vegetação ciliar ao longo do tempo? Quais os eventos históricos responsáveis por essas possíveis mudanças? Como os fazendeiros e funcionários representam os aspectos relacionados às utilidades e à conservação da vegetação ciliar? Um total de 17 homens e oito mulheres, proprietários e funcionários de áreas próximas à vegetação ripária em cinco municípios dos estados da Bahia e Pernambuco, participaram da pesquisa. Entrevistas semiestruturadas e entrevista semiestruturada do tipo projetiva foram empregadas para investigar as representações sobre conservação da mata ciliar e mudanças locais da paisagem, bem como resgatar os eventos históricos que as influenciaram. Com o objetivo de registrar o conhecimento local sobre a diversidade de espécies úteis mais importantes foi utilizada a técnica de lista livre. Em relação às modificações da paisagem verificou-se que apenas um entrevistado afirmou não haver mudanças na vegetação ciliar, seis afirmaram que houve mudanças para pior e quatro para melhor. Quatro proprietários responderam que as mudanças na vegetação iniciaram há 10 anos, seis há mais de 30 anos, dois não sabiam e um não verificou mudanças. Entre os funcionários, cinco afirmaram que elas ocorreram há mais de 20 anos, quatro há mais de 10 anos e para quatro deles a vegetação não mudou. Observou-se que todos os informantes concordaram que a vegetação deve ser conservada, sendo que 64% destacaram que ela protege o rio e os outros 36% indicaram outras utilidades para a vegetação ciliar, tais como: atrair chuva, fazer sombra, usos medicinais e aumentar a quantidade de oxigênio. Sobre quem seriam os responsáveis pela conservação: 48% disseram que eram os próprios proprietários de terras, 48% afirmaram que era dever de todos conservar e 4% atribuíram a responsabilidade ao IBAMA. Eles também apontaram soluções para a conservação da vegetação ripária, como o reflorestamento (39%), não desmatar (17%), educação ambiental (13%) e cuidar bem (13%). Futuros projetos de restauração que podem vir a ocorrer nessa área devem levar em consideração essas diferentes representações, demandas e expectativas

Produção e reprodução de animais silvestres - o caititu (Tayassu tajacu).

CONERA