Desenvolvimento de uma câmara de ionização para o LNLS

Orientador: Helio Cesar Nogueira TolentinoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: Apresentamos uma câmara de ionização para monitorar e medir a intensidade do feixe de raios-x. Este detector será utilizado em estações experimentais da fonte de radiação síncrotron, que está sendo construída pelo Laboratório Nacional de Luz Síncrotron -LNLS. A câmara de ionização tem a configuração de placas paralelas e pode trabalhar com diferentes tipos de gases e pressões. A calibração da câmara, ou seja, a relação entre a corrente gerada pela câmara e a intensidade dos fótons incidentes, foi obtida utilizando o ar a 1 atm para fótons com energias de 5,4 keV, 8,4 keV e 17,5 keV. A calibração mostrou uma baixa eficiência da câmara, principalmente para fótons com energias altas, motivando um estudo com outros tipos de gases (N2, He, Ar e mistura P-10) a diferentes pressões. Foi desenvolvida e caracterizada a eletrônica para leitura da câmara de ionização. O ruído e a instabilidade desta eletrônica mostraram desempenhos comparáveis a um eletrômetro comercialAbstract: We describe an ionization chamber for monitoring and measuring the x-ray beam intensity .This detector will be used in the workstations of the synchrotron radiation facility , which is being constructed at Laboratório Nacional de Luz Síncrotron -LNLS. The ionization chamber has the two parallel plates configuration, and works with different types of gas and pressures. The ionization chamber calibration, i.e., the relation between the ionization chamber current and photon intensity into the chamber, was obtained using the air at 1 atm for 5.4 keV, 8.4 keV and 17.5 keV photon energies. The calibration showed a low efficiency of the chamber, mainly for high energy photon. This result motivated to study the efficiencies for different gases (N2, He, Ar and P-10) at different pressures. We developed and characterized the electronic for the ionization chamber readout. The noise and the instabilities of this electronic is comparable with a commercial electrometerMestradoFísicaMestre em Físic

Energy-dispersive X-ray absorption spectroscopy at LNLS: Investigation on strongly correlated metal oxides

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure. © 2010 International Union of Crystallography. Printed in Singapore - all rights reserved.Fil: Cezar, Julio C.. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Souza Neto, Narcizo M.. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Piamonteze, Cínthia. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Tamura, Edilson. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Garcia, Flávio. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Carvalho, Edson J.. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Neueschwander, Régis T.. Laboratorio Nacional de Luz Síncrotron; BrasilFil: Ramos, Aline Y.. Centre National de la Recherche Scientifique; FranciaFil: Tolentino, Hélio C. N.. Centre National de la Recherche Scientifique; FranciaFil: Caneiro, Alberto. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Massa, Nestor Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Martinez Lope, Maria Jesus. Instituto de Ciencia de Materiales de Madrid; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Alonso, José Antonio. Instituto de Ciencia de Materiales de Madrid; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Itié, Jean Paul. L'Orme des Merisiers. Synchrotron SOLEIL; Franci

Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxides

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure.Facultad de Ciencias ExactasCentro de Química Inorgánic

Genetic variability of populations of Nyssomyia neivai in the Northern State of Paraná, Brazil

ABSTRACT The genetic study of sandfly populations needs to be further explored given the importance of these insects for public health. Were sequenced the NDH4 mitochondrial gene from populations of Nyssomyia neivai from Doutor Camargo, Lobato, Japira, and Porto Rico, municipalities in the State of Paraná, Brazil, to understand the genetic structure and gene flow. Eighty specimens of Ny. Neivai were sequenced, 20 from each municipality, and 269 base pairs were obtained. A total of 27 haplotypes and 28 polymorphic sites were found, along with a haplotypic diversity of 0.80696 and a nucleotide diversity of 0.00567. Haplotype H5, with 33 specimens, was the most common among the four populations. Only haplotypes H5 and H7 were present in all four populations. The population from Doutor Camargo showed the highest genetic diversity, and only this population shared haplotypes with those from the other municipalities. The highest number of haplotypes was sheared with Lobato which also had the highest number of unique haplotypes. This probably occurred because of constant anthropic changes that happened in the environment during the first half of the twentieth century, mainly after 1998. There was no significant correlation between genetic and geographical distances regarding these populations. However, the highest genetic and geographical distances, and the lowest gene flow were observed between Japira and Porto Rico. Geographical distance is a possible barrier between these municipalities through the blocking of haplotype sharing

Installation and operation of the LNLS double-crystal monochromator at CAMD

A new x-ray beamline has been installed at CAMD utilizing a two-crystal monochromator designed and built at LNLS. The beamline will operate in the 2-18 keV range using up to 4 mrad of dipole radiation from the CAMD storage ring. The monochromator maintains a fixed exit beam and fixed positions of the beam on the two crystals using mutually perpendicular elastic translations. With the ring operating at 1.5 GeV and 160 mA, Si(220) crystals will provide a flux of ∼3(109) photons/s/mrad at 8 keV, with an energy resolution ΔE\u3c2 eV, to the experimental hutch. The beamline is equipped with an EXAFS endstation and will also be used for other x-ray applications at CAMD. First results are presented. © 1995 American Institute of Physics

Energy-dispersive X-ray absorption spectroscopy at LNLS : investigation on strongly correlated metal oxides.

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure