172 research outputs found
Reflets dans l eau, de Claude Debussy: caminhos interpretativos revelados pela análise de gravações da obra
No full textThis paper presents the analysis of recordings of different interpretations of the piece Reflets dans l\'eau, cycle Images of Claude Debussy, and an interpretative proposal prepared by the researcher based on the study. The work Reflets dans l\'eau by Claude Debussy piece presents different rhythmic and harmonic material, either by the presence of unusual materials scalar tonal system or by the strong presence of rubato, which provides several options for the interpreter around agogic and dynamic. The emphasis on the sound, and consequently in listening as a basis for analyzing the work, provided comparative studies of recorded interpretations contributing to the understanding of aspects that are not explicitly revealed in musical notation, but which are parto f the interpretive process. The results coming from the comparative analysis of recordings on the computer provided quantitative data about the dimensions of time and dynamics, revealing how each artist used these resources to enhance certain moments in the work. To obtain the data and discussing the results, we chose to use the computing resources of audio analysis software Sonic Visualiser and the waveforms of the recordings. The similarities and differences pointed out between interpretations, brought satisfactory results and allowed to understand the interpretive options addressed. An interpretative proposal was brought by the researcher in the form of recording, followed by a discussion of interpretive options used. The research enabled the analysis of elements that are not always evident in the notation of the piece and that are important for planning and interpretive understanding of a musical work.Mestre em ArtesEste trabalho apresenta a análise de gravações de diferentes interpretações da obra Reflets dans l eau, do ciclo Images, de Claude Debussy, e uma proposta interpretativa elaborada pela pesquisadora com base no estudo realizado. A obra Reflets dans l eau de Claude Debussy é uma peça que possui materiais harmônicos e rítmicos diversos, seja pela presença de materiais escalares pouco usuais no sistema tonal ou pela forte presença do rubato, o qual fornece diversas opções para o intérprete em torno da agógica e da dinâmica. A ênfase no aspecto sonoro, e consequentemente na escuta, como base para a análise da obra, permitiu estudos comparativos de interpretações gravadas contribuindo para a compreensão de aspectos que não são revelados explicitamente na notação musical, mas que estão contidos no processo interpretativo. Os resultados advindos da análise comparativa de gravações no computador forneceram dados quantitativos acerca das dimensões do tempo e da dinâmica, revelando a maneira como cada intérprete utilizou esses recursos para valorizar determinados momentos na obra. Para a obtenção dos dados e a discussão dos resultados, optou-se pela utilização de recursos computacionais de análise de áudio do software Sonic Visualiser e da visualização das formas de onda das gravações. Os resultados se mostraram satisfatórios pois, ao apontar similaridades e diferenças entre as interpretações, permitiram compreender as opções interpretativas abordadas. Uma proposta interpretativa foi trazida pela pesquisadora em forma de gravação, seguida de uma discussão das opções interpretativas utilizadas. A pesquisa viabilizou a análise de elementos que nem sempre são evidenciados na notação da obra e que são importantes para o planejamento interpretativo e para a compreensão de uma obra musical
Reprint of: A supersonic jet target for the cross section measurement of the 12C(α, γ)16O reaction with the recoil mass separator ERNA
No full textC-12(alpha, gamma)O-16 cross section plays a key-role in the stellar evolution and nucleosynthesis of massive stars. Hence, it must be determined with the precision of about 10% at the relevant Gamow energy of 300 keV. The ERNA (European Recoil mass separator for Nuclear Astrophysics) collaboration measured, for the first time, the total cross section of C-12(alpha, gamma)O-16 by means of the direct detection of the O-16 ions produced in the reaction down to an energy of E-cm = 1.9 MeV. To extend the measurement at lower energy, it is necessary to limit the extension of the He gas target. This can be achieved using a supersonic jet, where the oblique shock waves and expansion fans formed at its boundaries confine the gas, which can be efficiently collected using a catcher. A test version of such a system has been designed, constructed and experimentally characterized as a bench mark for a full numerical simulation using FV (Finite Volume) methods. The results of the commissioning of the jet test version and the design of the new system that will be used in combination with ERNA are presented and discussed
Direct measurements of the 12 C+ 12 C reactions cross-sections towards astrophysical energies
No full textCarbon fusion reactions 12C(12C,p)23Na and 12C(12C,α)20Ne play a key role in the evolution of massive stars and in explosive scenarios such as type-Ia supernovae and super-bursts in binary stars. A direct determination of their cross sections is extremely challenging and discrepancies exist between different data sets in the literature. Here we report the results of a direct measurement performed at the CIRCE Tandem Accelerator Laboratory in Caserta (Italy), using ΔE- E detectors for unambiguous charge identification. Cross sections were measured in the energy range Ec. m.= 2.51 - 4.36 MeV with energy steps between 10 and 25 keV in the centre of mass. To our knowledge these represent the finest energy steps to date. Results are presented in the form of partial and summed astrophysical S~ -factors for individual proton- and α-particle channels. Branching ratios of individual proton- and α-particle groups were found to vary significantly with energy. Angular distributions, albeit limited to three angles, were also found to be non-isotropic, which could be a potential explanation for the discrepancies observed among different data sets. Further efforts are ongoing to extend measurements to lower energies
Understanding the mechanisms of nuclear collisions: A complete study of the B 10 + Sn 120 reaction
No full textBackground: Reactions involving exotic and stable weakly bound nuclei have been extensively studied in recent years. Although several models have been successfully used to explain particular reaction outcomes, the answers to many questions remain elusive. In previous works, we presented elastic, inelastic, and transfer angular distributions for the B10+Sn120 system measured at ELab=31.5, 33.0, 35.0, and 37.5 MeV. The data set was analyzed through coupled reaction channels calculations in the context of the double-folding São Paulo potential. Purpose: We investigate nuclear reaction mechanisms for systems involving weakly bound projectiles. Method: Angular distributions for several nuclear reaction processes were measured for the B10+Sn120 system at ELab=39.70 MeV. Results: The new data set involves angular distributions for elastic scattering, projectile and target inelastic excitations, one-neutron pickup transfer, one-proton stripping transfer, deuteron pickup transfer, and He3,4 stripping transfer. We have also observed Be10 nuclei. The effect of the couplings to some nonelastic states on the angular distributions is discussed. Conclusion: The theoretical calculations within the coupled reaction channels formalism provide an overall good agreement with the corresponding inelastic, one-neutron stripping, one-proton pickup, one-deuteron pickup, and He3 stripping transfer data. However, to improve the description of the elastic scattering angular distribution, the inclusion of additional channels in the coupling scheme might be necessary.Fil: Gasques, L. R.. Universidade de Sao Paulo; BrasilFil: Alvarez, M. A. G.. Universidad de Sevilla; EspañaFil: Arazi, Andres. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carlson, B. V.. Instituto Tecnológico de Aeronáutica; BrasilFil: Chamon, L. C.. Universidade de Sao Paulo; BrasilFil: Fernández García, J. P.. Universidad de Sevilla; EspañaFil: Lépine Szily, A.. Universidade de Sao Paulo; BrasilFil: Lubian, J.. Universidade Federal Fluminense; BrasilFil: Rangel, J.. Universidade Federal Fluminense; BrasilFil: Rodríguez Gallardo, M.. Universidad de Sevilla; EspañaFil: Scarduelli, V.. Universidade de Sao Paulo; BrasilFil: Zagatto, V. A. B.. Universidade Federal Fluminense; Brasi
Energy calibration and stability of the 3 MV accelerator at CIRCE for applications in Nuclear Astrophysics
No full textA 3 MV NEC 9SDH-2 Pelletron accelerator is installed at the Center for Isotopic Research on Cultural and Environmental Heritage of Dipartimento di Matematica e Fisica, Università degli Studi della Campania “Luigi Vanvitelli”, Caserta (CIRCE-DMF). The accelerator serves several beam lines devoted to both applied and fundamental research. While generally a precise and accurate knowledge of the energy of the charged particle beams is of interest for all applications, the measurement of charged particle nuclear reactions of astrophysical energies is particularly demanding because of the strong energy dependence of the cross section below the Coulomb barrier and the very long duration of the measurements. We describe here the energy calibration of the accelerator installed at CIRCE-DMF and a measurement of the short term stability. A routine to improve the long term stability and remove the observed dependence of the terminal voltage on the injected current was successfully tested. Finally, possible improvements are discussed
A supersonic jet target for the cross section measurement of the 12 C(α, γ) 16 O reaction with the recoil mass separator ERNA
No full text12C(α, Î3)16O cross section plays a key-role in the stellar evolution and nucleosynthesis of massive stars. Hence, it must be determined with the precision of about 10% at the relevant Gamow energy of 300 keV. The ERNA (European Recoil mass separator for Nuclear Astrophysics) collaboration measured, for the first time, the total cross section of 12C(α, Î3)16O by means of the direct detection of the 16O ions produced in the reaction down to an energy of Ecm = 1.9 MeV. To extend the measurement at lower energy, it is necessary to limit the extension of the He gas target. This can be achieved using a supersonic jet, where the oblique shock waves and expansion fans formed at its boundaries confine the gas, which can be efficiently collected using a catcher. A test version of such a system has been designed, constructed and experimentally characterized as a bench mark for a full numerical simulation using FV (Finite Volume) methods. The results of the commissioning of the jet test version and the design of the new system that will be used in combination with ERNA are presented and discussed
Reduction of deuterium content in carbon targets for 12C+12C reaction studies of astrophysical interest
No full textThe 12C(12C,p)23Na and 12C(12C,α)20Ne fusion reactions are among the most important in stellar evolution since they determine the destiny of massive (M≃ 8 - 10 M⊙) stars. However, experimental low-energy investigations of such reactions are significantly hampered by ubiquitous natural hydrogen and deuterium contaminants in the carbon targets. The associated beam-induced background completely masks the reaction products of interest thus preventing cross-section measurements at the relevant energies of astrophysical interest, Ecm< 2 MeV. In this work, we report about an investigation aimed at assessing possible deuterium reductions on both natural graphite and Highly Ordered Pyrolytic Graphite targets as a function of target temperature. Our results indicate that reductions up to about 80% can be attained on both targets in the temperature range investigated, T≃ 200 - 1200 ∘C. A further reduction by a factor of 2.5 in absolute deuterium content is observed when the scattering chamber is surrounded by a dry nitrogen atmosphere so as to minimise light-particles uptake within the chamber rest gas (and thus on target) through air leaks. The results from this study will inform the choice of optimal experimental conditions and procedures for improved measurements of the 12C + 12C reactions cross-sections at the low energies of astrophysical interest
Measurement of 1323 and 1487 keV resonances in N15(α,γ)F19 with the recoil separator ERNA
No full textBackground: The origin of fluorine is a widely debated issue. Nevertheless, the 15N(α,γ)19F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the direct capture and the tails of the two broad resonances at Ec.m.=1323 and 1487 keV.
Purpose: The broad resonances widths, Γγ and Γα, have to be measured with adequate precision in order to better determine their contribution to the 15N(α,γ)19F stellar reaction rate.
Methods: Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m.=1323 and 1487 keV is used to determine their widths in the α and γ channels.
Results: We show that a direct measurement of the cross section of the 15N(α,γ)19F reaction can be successfully obtained with the recoil separator ERNA, and the widths Γγ and Γα of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance Γα.
Conclusions: The revision of the widths of the two more relevant broad resonances in the 15N(α,γ)19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the 19F stellar nucleosynthesis is dominated by the uncertainties affecting the direct capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments
Nuclear physics midterm plan at Legnaro National Laboratories (LNL)
No full textThe next years will see the completion of the radioactive ion beam facility SPES (Selective Production of Exotic Species)and the upgrade of the accelerators complex at Istituto Nazionale di Fisica Nucleare – Legnaro National Laboratories (LNL) openingup new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics, and applications. The nuclear physicscommunity has organised a workshop to discuss the new physics opportunities that will be possible in the near future by employingstate-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.Fil: Ballan, M.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Bottoni, S.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Caamaño, M.. Universidad de Santiago de Compostela; EspañaFil: Caciolli, A.. Istituto Nazionale di Fisica Nucleare; Italia. Università di Padova; ItaliaFil: Campostrini, M.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Cicerchia, M.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Crespi, F. C. L.. Università degli Studi di Milano; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Cristallo, S.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Dell’Aquila, D.. Istituto Nazionale di Fisica Nucleare; Italia. Università degli Studi di Napoli Federico II; ItaliaFil: Depalo, R.. Istituto Nazionale di Fisica Nucleare; Italia. Università degli Studi di Milano; ItaliaFil: Fioretto, E.. Università degli Studi di Milano; ItaliaFil: Galtarossa, F.. Istituto Nazionale di Fisica Nucleare; Italia. Università di Padova; ItaliaFil: Gasques, L. R.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Gottardo, A.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Gramegna, F.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Gulminelli, F.. Centre National de la Recherche Scientifique; FranciaFil: Kurtukian Nieto, T.. Université de Bordeaux; FranciaFil: La Cognata, M.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Lenzi, S. M.. Istituto Nazionale di Fisica Nucleare; Italia. Università di Padova; ItaliaFil: Marchi, T.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Mazurek, K.. Institute of Nuclear Physics Polish Academy of Sciences; PoloniaFil: Mengoni, D.. Università di Padova; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Mou, L.. Università di Ferrara; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Arazi, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Wheldon, C.. University Of Birmingham;Fil: Wieland, O.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Wimmer, K.. GSI Helmholtzzentrum für Schwerionenforschung; AlemaniaFil: Wyss, J.. Istituto Nazionale di Fisica Nucleare; Italia. Università degli Studi di Cassino e del Lazio Meridionale; ItaliaFil: Zago, L.. Università di Padova; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Zenoni, A.. Istituto Nazionale di Fisica Nucleare; Italia. Universitá degli Studi di Brescia; Itali
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