55 research outputs found

    The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities

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    The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich heavy-ions systems at intermediate energies has been proposed as an observable sensitive to the strength of the symmetry term in the nuclear Equation Of State (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for 197^{197}Au+197^{197}Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.Comment: Talk given by P. Russotto at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

    Free-standing supercapacitors from Kraft lignin nanofibers with remarkable volumetric energy density

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    We have discovered a very simple method to address the challenge associated with the low volumetric energy density of free-standing carbon nanofiber electrodes for supercapacitors by electrospinning Kraft lignin in the presence of an oxidizing salt (NaNO₃) and subsequent carbonization in a reducing atmosphere. The presence of the oxidative salt decreases the diameter of the resulting carbon nanofibers doubling their packing density from 0.51 to 1.03 mg cm⁻² and hence doubling the volumetric energy density. At the same time, the oxidative NaNO₃ salt eletrospun and carbonized together with lignin dissolved in NaOH acts as a template to increase the microporosity, thus contributing to a good gravimetric energy density. By simply adjusting the process parameters (amount of oxidizing/reducing agent), the gravimetric and volumetric energy density of the resulting lignin free-standing carbon nanofiber electrodes can be carefully tailored to fit specific power to energy demands. The areal capacitance increased from 147 mF cm⁻² in the absence of NaNO₃ to 350 mF cm⁻² with NaNO₃ translating into a volumetric energy density increase from 949 μW h cm⁻³ without NaNO₃ to 2245 μW h cm⁻³ with NaNO₃. Meanwhile, the gravimetric capacitance also increased from 151 F g⁻¹ without to 192 F g⁻¹ with NaNO

    Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

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    Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from C10,12-18 and B10-15 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1pxn) for relativistic C10,12-18 and B10-15 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study

    Coulomb dissociation of N 20,21

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    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at

    Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

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    Avaliação da estrutura dos centros de atenção psicossocial do município de São Paulo, SP Evaluación de la estructura de los centros de atención psicosocial del municipio de Sao Paulo, Sureste de Brasil Evaluation of psychosocial healthcare services in the city of São Paulo, Southeastern Brazil

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    OBJETIVO: Descrever a estrutura física, recursos humanos e modalidades de atenção existentes nos centros de atenção psicossocial (CAPS). MÉTODOS: Foram incluídos no estudo 21 CAPS para atendimento de adultos, vinculados à Secretaria Municipal de Saúde de São Paulo (SP), entre 2007 e 2008. Foram coletadas informações sobre as instalações físicas dos serviços, recursos humanos disponíveis e procedimentos de cuidado ao paciente, utilizando instrumento padronizado. Foram realizados análise descritiva dos dados e o teste de qui-quadrado para testar a associação entre os tipos de atividades e a origem e localização dos serviços. RESULTADOS: Dez serviços foram criados como ambulatórios e posteriormente transformados, oito eram hospitais-dia e apenas três foram criados como CAPS. Nenhum serviço funcionava diariamente durante 24 horas. Metade dos serviços funcionava em imóveis alugados, com instalações físicas inadequadas especialmente para atendimentos grupais. A composição das equipes dos serviços foi bastante diversa. As atividades desempenhadas nos CAPS foram heterogêneas, com maior valorização das atividades grupais desenvolvidas com usuários dentro dos CAPS e pouca integração aos outros equipamentos de saúde. As atividades grupais de arte e cultura foram as mais freqüentes em todos os serviços. Os serviços de origem ambulatorial apresentavam atividades artesanais e os que haviam sido hospitais-dia realizavam mais atividades de integração psicofísica. O perfil de atividades relacionou-se à distribuição regional dos serviços. CONCLUSÕES: A heterogeneidade dos CAPS parece se relacionar à história dos programas de saúde mental implementados no município desde a década de 1980 e à diversidade socioeconômica e cultural das regiões da cidade, bem como às diferentes composições das equipes observadas. Diferentes modelos de atenção psicossocial foram encontrados, desde a constituição de "equipamentos-síntese" dos quais os usuários não recebem alta, até serviços que encaminham e dão alta após a estabilização dos sintomas dos usuários, numa tentativa de construção de uma rede de cuidados.<br>OBJETIVO: Describir la estructura física, recursos humanos y modalidades de atención existentes en los centros de atención psicosocial (CAPS). MÉTODOS: Fueron incluidos en el estudio 21 CAPS para atención de adultos, vinculados a la Secretaria Municipal de Salud de Sao Paulo (Sureste de Brasil), entre 2007 y 2008. Fueron colectadas informaciones sobre las instalaciones físicas de los servicios, recursos humanos disponibles y procedimientos de cuidado al paciente, utilizando instrumento estandarizado. Fueron realizados análisis descriptivos de los datos y la prueba de Chi-cuadrado para evaluar la asociación entre los tipos de actividades y el origen y localización de los servicios. RESULTADOS: Diez servicios fueron creados como ambulatorios y posteriormente transformados, ocho eran hospitales-día y apenas tres fueron creados como CAPS. Ningún servicio funcionaba diariamente durante 24 horas. Mitad de los servicios funcionaba en inmuebles alquilados, con instalaciones físicas inadecuadas especialmente para atenciones grupales. La composición de los equipos de servicios fue bastante diversa. Las actividades desempeñadas en los CAPS fueron heterogéneas, con mayor valorización de las actividades grupales desarrolladas con usuarios dentro de los CAPS y poca integración a los otros equipos de salud. Los servicios de origen ambulatorio presentaban actividades artesanales y los que habían sido hospitales-día realizaban más actividades de integración psicofísica. El perfil de actividades se relacionó con la distribución regional de los servicios. CONCLUSIONES: La heterogeneidad de los CAPS parece relacionarse con la historia de los programas de salud mental implementados en el municipio desde la década de 1980 y a la diversidad socioeconómica y cultural de las regiones de la ciudad, bien como a las diferentes composiciones de los equipos observados. Diferentes modelos de atención psicosocial fueron encontrados, desde la constitución de "equipos-síntesis" de los cuales los usuarios no reciben alta, hasta servicios que encaminan y dan alta posterior a la estabilización de los síntomas de los usuarios, en un intento de construcción de una red de cuidados.<br>OBJECTIVE: To describe infrastructure, human resources, and care approaches in psychosocial healthcare services. METHODS: Descriptive study including 21 psychossocial healthcare services for adults affiliated to the local health department in the city of São Paulo, Southeastern Brazil, conducted between 2007 and 2008. Information about infrastructure of facilities, human resources available and patient care was collected using a standardized instrument. There were performed descriptive data analysis and chi-square test to test the association between care activities and service source and location. RESULTS: Ten services were first created as outpatient clinics and later adapted, eight were day hospitals and only three were created as psychosocial healthcare services. None of them was open 24 hours a day. Half of them were located in rented buildings with inadequate infrastructure especially for group activities. Staff composition was very different among services, with emphasis on on-site group activities and little integration to other health services. All services provided mostly arts and cultural activities. Earlier outpatient services provided mainly craft activities and former day-hospitals offered mostly psychophysical integration activities. The profile of activities varied according to the geographical distribution of services. CONCLUSIONS: Current heterogeneous character of psychosocial healthcare services seems associated to the history of mental health care programs that have been implemented in São Paulo since 1980s and to social, economic and cultural differences in different areas of the city. Different psychosocial care approaches were found ranging from on-site care with little integration with other health services to services that refer their users to other services after symptoms become stable in an attempt to create a network of mental health care
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